CA2405174A1 - Stirling engine - Google Patents
Stirling engine Download PDFInfo
- Publication number
- CA2405174A1 CA2405174A1 CA002405174A CA2405174A CA2405174A1 CA 2405174 A1 CA2405174 A1 CA 2405174A1 CA 002405174 A CA002405174 A CA 002405174A CA 2405174 A CA2405174 A CA 2405174A CA 2405174 A1 CA2405174 A1 CA 2405174A1
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- Canada
- Prior art keywords
- stirling engine
- engine according
- lever
- piston
- displacement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/04—Engines with variable distances between pistons at top dead-centre positions and cylinder heads
- F02B75/045—Engines with variable distances between pistons at top dead-centre positions and cylinder heads by means of a variable connecting rod length
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- F02G1/00—Hot gas positive-displacement engine plants
- F02G1/04—Hot gas positive-displacement engine plants of closed-cycle type
- F02G1/043—Hot gas positive-displacement engine plants of closed-cycle type the engine being operated by expansion and contraction of a mass of working gas which is heated and cooled in one of a plurality of constantly communicating expansible chambers, e.g. Stirling cycle type engines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- F02G1/00—Hot gas positive-displacement engine plants
- F02G1/06—Controlling
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- F02G2244/00—Machines having two pistons
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
- F02G2270/00—Constructional features
- F02G2270/42—Displacer drives
- F02G2270/425—Displacer drives the displacer being driven by a four-bar mechanism, e.g. a rhombic mechanism
Abstract
The invention relates to a Stirling engine (10, 50, 72) comprising at least one working piston (52) and at least one displacement piston (4). According to the invention, a lever (5), to which an adjustable pivot point (7) is assign ed and which is pivotally connected to the input and output parts (2, 8), is provided for controlling power by transferring the linear movement of an inp ut part (2) into the linear movement of an output part (8). During the transfer of movement, the bearing point of the lever (5) travels along a specified curve on the pivot point (7).
Description
The invention relates to a Stirling engine com-prising at least one working piston and at least one displacement piston.
Depending on what type of drive unit is provided for a rotary drive, there are many possible ways of controlling the power of the rotary drive. In combus-tion engines, the power can be controlled very well via the fuel supply, whereas, e.g., in Stirling engines a power control without a loss in efficiency has been a great problem for quite some time. For controlling the power of Stirling engines it has been known to change the clearance volumes, on the one hand, and to change the pressure of the working gas, on the other hand, wherein, however, losses in efficiency, or relatively long reduction times, respectively, occur with both types of power control.
From US 3 886 744 A, e.g., a power control system for a Stirling engine is known in which the inlet pres-sure of the hot air is controlled via an annular con-trol element which opens or closes the inlet depending on the differential pressure present; this has the dis-advantage that a very complex construction is provided and that the efficiency of the Stirling engine declines as a consequence of the pressure control.
From US 2 873 611 A, a combustion engine is known in which the stroke of a piston can be changed with the assistance of a circular-arc-shaped lever arm, and thus the power of the driven-side crank can be adjusted. For this purpose, the lever arm has a connecting link guide in which a connecting head is slidably mounted. Since, however, in combustion engines numerous other advanta-geous possibilities are available for an efficient power control, such an arrangement is not suitable in combustion engines.
The invention has as its object to provide a Stir-ling engine of the initially defined type with which a rapid power control is possible without lowering its efficiency.
The Stirling engine according to the invention and of the initially defined type is characterized in that for a power control by means of the transmission of the linear movement of a drive part into the linear move-ment~of a driven part, a lever articulately connected to the drive part and.the driven part is provided, which lever has an associated displaceable pivot point, the bearing point of the lever traveling on the pivot point according to a curve during the movement trans-mission. This curve may have any shape desired - de-pending on the requirements of the movement transmission and on the type of the respective Stirling engine.
. Since the theoretical power of a Stirling engine -considering an isothermal expansion and compression -can be expressed by P-(I-T)~*~ y~",~*P,~ S *sin0 , with 60 I+ I-62 P...... power i...... temperature ratio between compression space and expansion space, n...... number of revolutions (U/min]
VE,",~,~... maximum volume of the expansion space V~.~...maximum volume of the compression space Pm..... effective mean pressure 8...... pressure ratio of engine and wsin ~p ~...tan0= , r + wcos tp with cp = phase angle between working piston and dis-placement piston, and w= ~~"'~ the ratio of the maximum volumes of compres-E,max sion and expansion, as well as T= ~~ the t emperature E
ratio between compression volume and expansion volume, a power control can be carried out by means of the lever arrangement according to the characterizing part of claim 1 without any losses in efficiency, since preferably the maximum compression volume V~,~ and, thus, 'the pressure ratios 8 of the engine can be con-trolled very well.
By adjusting the pivot point on which the lever or its bearing point, respectively, travel during the movement transmission, thus the velocity and the accel-eration of the driven part and a change in the maximum volumes of the compression space caused thereby can be obtained in a very simple way, whereby the power of the Stirling engine can be controlled.
For realizing the change of the bearing point of the lever during the movement transmission with a sim-ple construction, it is advantageous if the lever has a connecting link defining the given curve, which con-necting link slides over the pivot point, e.g. via a roller defining this pivot point, during the movement transmission.
For a well-defined power control of the Stirling engine it has proven particularly advantageous if the curve or connecting link has the shape of a circular arc; yet other curve shapes are, of course, also con-ceivable for certain purposes of use, ~.g, two tangen-tially connected circular arc segments, or an elliptical shape.
To allow. for a simple adjustment of the pivot point, it is advantageous if the pivot point is ar-ranged on a pivot arm.
Shifting of the pivot point can be realized in a structurally particularly simple manner if the pivot arm is connected to an adjustment device.
To equally adjust each point of rotation of two levers - in case at least two cylinders are used, it is advantageous if the adjustment device is connected to a pivot arm via one linkage each and is symmetrically provided between at least two levers.
For a simple configuration of the adjustment de-vice in terms of construction, it is suitable if a spindle drive is provided as the adjustment device.
If a connecting link guide is provided in which the end of the linkage arranged opposite the pivot arm is displaceably and fixably received, the position of the pivot~arm can be changed in a simple and quick man-ner and thus, the power of the Stirling engine can be adjusted.
In a Stirling engine with a double-active working cylinder, in which the movement of the working piston occurs in a sine-shape, it is advantageous if the dis-placement piston is associated with the lever for a power control, whereby a dynamic stroke change as well as a discontinuous movement of the displacement piston will occur.
In a ~-Stirling engine, with which in general higher mechanic efficiencies are obtained than with the remaining types of Stirling engines, the displacement piston and the working piston are located in a common cylinder, whereby, in theory, it is possible for,the entire gas mass to be located in the hot space during the expansion phase and to be located in the cold space during the compression phase. For an efficiency-neutral power control it is then advantageous if the working piston is associated with the lever with a displaceable pivot point, and the displacement lever is associated with a lever with a non-displaceable pivot point.
In a double-active engine, in which the working piston and the displacement piston form one unit for the purpose of a simple construction of the Stirling engine, this unit is associated with the lever for an advantageous power control.
For a reliable movement of the displacement piston and of the working piston, respectively, it is suitable if the drive part is articulately connected to a piston rod which is linearly guided in a straight-line guide and connected to the displacement piston or to the working piston, respectively.
For the required heat exchange to the working gas between the heater and cooler surfaces, respectively, it is suitable if the displacement piston on both sides and the working piston on one side thereof has a wave-shaped section capable of engaging in the neighboring heater or cooler surfaces, respectively. In this man-ner, substantially larger surfaces can get into contact with the working gas, as compared to plane surfaces. As regards a high strength of the displacement piston, it is suitable if the lamella-type wave-shaped sections of the displacement piston are arranged to be turned by 90° relative to each other. Also for a high strength it is advantageous if the lamella-type thin-walled wave-shaped sections of the working piston or heater head, respectively, are supported by stiffening ribs at the burner side and at the coolant side, respectively. An integration of heater-, regenerator- and cooler-sur-faces directly into the working space is particularly advantageous in terms of efficiency and of minimizing the detrimental volume of a Stirling engine.
Instead of cooperating at the driven side with a conventional crankshaft, it may be advantageous in terms of the kinematics for a maximum approach to the ideal circle process, if the linear movement of the driven part is converted into a rotational movement by means of a connecting link which serves as a crank.
In the following, the invention will be described in more detail by way of preferred exemplary embodi-ments illustrated in the drawings to which, however, it shall not be restricted. In detail, in the drawings, Fig. 1 shows a schematic view of an arrangement for the controlled conversion of linear movements, wherein a drive part, the linear movement of which is converted via a lever whose bearing point travels on the pivot point according to a curve, is in its lower end position;
Fig. 2 shows a view of an arrangement according to Fig. 1, wherein the drive part is in a middle, or zero position, respectively;
Fig. 3 shows a view of the arrangement according to Figs. 1 and 2, wherein the drive part is in an upper end position;
Fig. 4 shows a view of a Stirling engine with two displacement units and one arrangement each for con-trolling the reciprocating movement of a displacement piston;
Fig. 5 shows a side view of the Stirling engine according to arrow V of Fig. 4;
Fig. 6 shows a sectional representation according to line VI-VI of Fig. 5;
Fig..7 shows a perspective view of the Stirling engine according to Figs. 4 to 6;
Fig. 8 shows an exploded view of a displacement unit of the Stirling engine with cooler and heater sur-faces, respectively, which have a wave-shaped section;
Fig. 9 shows a perspective view of a displacement piston for a reciprocating movement in a displacement unit according to Fig. 8;
Fig. 10 shows an exploded view of the displacement piston according to Fig. 9;
Figs. 11a to 11d are different graphs regarding the Stirling engine illustrated in Figs. 4 to 7, a dif-ferent position of the pivot point of the lever for controlling the reciprocating movement of the drive _ 8 _ part being shown in each case;
Fig. 12 shows a view of a (3-Stirling-two-cylinder engine comprising two displacement units and one device each for controlling, over time, the stroke movement and the movement of a working piston;
Fig. 13 is a partially broken away side .view of the (3-engine according to Fig. 12;
Fig. 14 is a sectional representation according to line XIV-XIV of Fig. 13, with the pivot points being at their maximum power position and the working pistons reaching their maximum stroke;
Fig. 15 is a side view of the ~i-engine according to Fig. 14, with the pivot points being in an interme-diate position;
Fig. 16 shows a view of the (3-engine according to Figs. 14 and 15, with the pivot points being in a power-minimizing position;
Fig. 17 shows a perspective view of the sectional representation according to Figs. 14 to 16;
Fig. 18 shows an exploded view of the ~i-engine ac-cording to Figs. 12 to 17;
Figs. 19a to 19d show different graphs regarding the (3-engine illustrated in Figs. 12 to 18, each graph showing a different position of the pivot point of the lever for controlling the receiprocating movement of the drive shaft;
_ g _ Fig. 20 shows a view of a double-active Stirling engine with an arrangement for the controlled conver-sion of linear movements; and Fig. 21 shows a sectional representation according to line XXT-XXI of Fig. 20.
In Figs. 1 to 3, an arrangement 1 for the con-trolled conversion of linear movements is shown, wherein a connecting rod 2 working as drive part is provided which is articulately connected to a piston rod 3 of a displacement piston 4 of a Stirling en-gine (cf. Fig. 6). Via an axle 2', the connecting rod 2 furthermore is articulately connected to a lever 5 which has a given control curve in the form of a con-necting link 6 in which a roller 7 freely rotatable about an axle 7' and serving as a pivot point for lever (subsequently, therefore, also being termed "roll-lever") is provided. The other end of the lever 5, which is, substantially angled by 90°, is articulately connected about an. axis 8' to a driven rod 8 to which the linear movement of the displacement piston rod 3 is transmitted. The driven rod 8 in turn is linearly mounted, yet turned by 90° with a view to the linear movement of the displacement piston rod 3.
As is visible from Figs. 1 to 3, the bearing point of lever 5, depending on the position of the displace-~ment piston rod 3, or of the connecting rod 2, respec-tively, moves along a curve 6' defined by the connecting link 6.
One of the essential parameters for determining the transmission of movement between the displacement piston rod 3 and the driven rod 8 is the distance LR
(cf. Fig.2) between the axis of rotation 8' between be lever 5 and the driven rod 8 and the axis of rotation 7' on which roller 7 is rotatably mounted. This dis -tance LR can be expressed as LR(x)= y~+(zl+x)Z
wherein x is the horizontal position of the axis of ro-tation 8' (and, thus, the displacement of the driven rod 8), y is the vertical distance between the axes of rotation 8' and 7', and z~ is the horizontal distance between the two axes of rotation 8', 7'.
Furthermore, the angle a enclosed by the imaginary connecting line between the axes of rotation 7', 8' to the vertical line, is important for the transmission of movement, and this angle a can be expressed by zi+x a(x)=~~ , y~
whereas the change ~a of this angle can be indicated as z~+x z1 d a = arctan - arctan - , y, v, with the intermediate or zero position shown in Fig. 2, in which one leg of the lever 5 is horizontal and the other leg of lever 5 ~.s vertical, being taken as a ref-- 1I. -erence.
Fur~.hexmore, the angle {i between the connecting line between the axes of rotation 7', 8' and the con-necting line between the axes of rotation 7', 2' is of importance for the transmission of movement, wherein ~{x)=arccos LR{x)2~a2 2 a2+RZ*LR(x) or y~+z~+a2 ~(0)=arccos , respectively, 2 a2+R2 y~+z~
and 4~=~'(x)-~(~) with R being the adjustable rolling radius of roller 7 and ~ being the vertical distance of the imaginary cen-ter of the rolling radius from the middle line of driven rod 8. Furthermore, the position of the axis of rotation 2' is. of importance, which is dependent on the respective positions of the drive rod, and driven rod, respectively, and thus can be expressed as x'(x)=-LR'*cosc~{x)+x and y'(x)=LR'*sincp(x) . respectively, wherein the angle ~, with the assistance of the differ-ence angles ~a and A(i, respectively, can be expressed as fi(x)=Q~(0)-~a-ds , wherein in the intermediate posi-tion ~(0)=arctan R+b and ~ is the horizontal distance between the imaginary roll-circuit center R and the axis 2' in the intermedi-ate position. LR' is the distance between the axes of rotation 8' and 2', and thus can be expressed as LR'= (R+a)2+(R+b)2 With the assistance of the axis of rotation 3' be-tween the displacement piston rod 3 and the connecting rod 2, the position of the displacement piston rod 3 can be expressed as P(x)= IZ-(c+x'(x))2+Y'(x) wherein the axis of rotation in its position shown in Fig. 2 is present in the position p(0)= 12-(c-b-R)2-(a+R) and wherein ,~ represents the length of connecting rod 2 and .~ indicates the horizontal distance of axis 8' in the reference position from the middle axis of the dis-placement piston rod 3.
In Fig. 3, the displacement piston rod 3 is illus-trated in its uppermost position, it being visible that roller 7 comes to rest against the rim of connecting link 6 neither in this extreme position nor in the ex-treme position illustrated in Fig. 1.
In Fig. 4, a Stirling engine 10 comprising ar-rangements 1 for the controlled linear movement trans-mission from a respective displacement piston rod 3 to an associated driven rod 8 is illustrated. The Stirling engine 20 has two displacement units 11 in which one displacement piston 4 each is reciprocated. The move-ment described by the respective lever 5 can be changed by adjusting the position of roller 7 which is adjust-able via a pivot arm 12. For adjusting the position of pivot arm 12, one linkage 13 each is provided which is adjustable with the assistance of a common spindle drive 14 via an adjustment wheel 15. By upward rotation of the adjustment wheel 15, the position of rollers 7 can be changed such that a power change will result therefrom, as can be seen from Figs. 11a to 11d.
In the Fig. 5 side view of the Stirling engine 10, the working cylinder 16 can be seen which is fed via a duct 17. Via a duct 19 and via a heat exchanger 20, fresh air heated with the assistance of the heat of the waste gas supplied via a duct 21 is introduced for com-bustion purposes info a combustion space 18 (cf. Fig.
6) of the displacement unit 11, which fresh air, after having passed the heat exchanger 20, can escape into the environment via duct 22.
In Fig. 6, a section of the Stirling engine l0 ac-cording to line VI-VI of Fig. 5 is shown; there, a wave-shaped section 23 of the cooler surfaces 24 and heater surfaces 25, respectively, can be seen, with these heat exchanger surfaces 24, 25 possibly being made of ceramics, e.g.. The heater surfaces 25 follow upon the combustion spaces 18, in which one burner 26 each is provided for the heating, or combustion, re-spectively, of the already pre-heated fresh air intro-duced via ducts 19. The displacement piston 4 shifts the working gas between a hot chamber 27 and a cool chamber 28, the middle part 37 of the displacement pis-ton 4 containing the regenerator (cf. Fig. 5).
Furthermore, it can be seen in Fig. 6 that the connecting rod 2 is connected by a hinge 3' guided in a straight-line guide 30 so as to guide the displacement piston rod 3. To transmit the movement from the driven rod 8 to a crankshaft 31 (cf. Fig. 5), a type of crank drive 32 (Fig. 6) is provided.
In Fig. 7, a perspective view of the Stirling en-gine 10 comprising the arrangements 1 associated with the displacement units 11 and provided for the con-trolled transmission of the linear movements of the connecting rods 3 is shown. Furthermore, the adjustment mechanism for the rollers 7 via rods 13 can be seen which, by rotating the adjustment wheel 15, allows for an adjustment of the position of the rollers 7, whereby in turn a power control of the Stirling engine 10 by the altered reciprocating movement of the displacement piston 4 is provided.
_ 15. _ In Fig. 8, an exploded view of the displacement unit 11 is shown. In the cooler lid region, substan-tially the straight-line guide 30 for receiving the ar-ticulated connection between the displacement piston rod 3 and the connecting rod 2 is shown, which straight-line guide is screwed to the cooler-side lid 33. The heat exchanger surface 24 provided for cooling is connected to the cooler-side lid 33 via several screws 34. Furthermore, a cylinder 35 is provided on which the duct 17 is provided for the spatial connec-tion with the working cylinder 16. Just like the cool heat exchanger surface 24, the hot heat exchanger sur-face 25 has a wave-type surface section on either side for stability purposes which preferably is rotated by 90°, so as to obtain as large a surface as possible, which enhances a heat exchange between the hot and the cool surface, respectively, and the displacement cham-ber.
From Figs. 9 and 10 it can be seen that a roller 36 is provided at the connecting-rod-side end of the displacement piston rod 3, which roller slides in the straight-line guide 30, whereby the linear guidance of the displacement piston 4 is ensured. The displacement piston 10 consists of three individual parts, section halves 38 each being screwed to a regenerator disc 37, which section halves have the aforementioned wave-type section provided for mutual engagement with the wave-type section of the heat exchanger surfaces 24 and 25, respectively. The regenerator disk 37 which may, e.g., be made of ceramics, has slot-shaped cavities 37' in which a regenerator material, e.g. sintered steel wool having a porosity of approximately 60-70~, is embedded.
Figs. 11a to 11d show, in four graphs each, four different adjustments of the position of the roller 7 supporting the roll-lever 5. Each one of Figs. 11a tb 11d includes a p-V diagram I, a graph II of the chang-ing volumes during a complete reciprocation of the working piston and of the displacement piston, respec-tively, a graph III of the piston positions of the working piston as well as of the displacement piston over a complete cycle, and a standardized illustration IV of the piston positions of the working and displace-ment pistons as regards their extreme positions made possible in accordance with the adjustment of the roller 7.
From Fig. 11a it can be seen that a power increase is possible with a position of the roller 7 pivoted very much out of the vertical, in which the phase shift between the course 40 of the working piston and the course 41 of the displacement piston has been reduced from 90° to approximately 85° (cf. illustration III), whereby a maximum pressure 45 (cf. diagram I) which is the same as compared to a normal sine course 42 is at-tained, and the power in the example illustrated in Fig. 11a can be increased to 102.6 kW (cf. computer-simulated p-V-course 44 with roll-lever control) as compared to 97.6 kW (cf. computer-simulated p-v-course 43) with a conventional sine course of the displacement piston 42.
From graph II it can be seen from the course of the working volume 46 and of the displacement volume 47 that in the adjusted position illustrated in Fig. 11a, the entire volumes of the working and displacement pis-tons are utilized. Moreover, in the standardized graphs IV of Figs. 11a to 11d, the relative piston course 48 of the working piston and the relative piston course 49 of the displacement piston are illustrated.
At an upward rotation of the adjustment wheel 15, by which the roller 7 is displaced towards a vertical position, as is visible from Figs. 11b to 11d, depend-ing on the position of the roller 7, the maximum stroke of the displacement piston 4 is reduced (cf. graphs III
in Figs. 11b and 11c), whereby the active volume of the displacement piston 4 is reduced (cf. graphs II), and thus an efficiency-neutral power control of the Stir-ling engine 10 is achieved.
From Fig. 11d, in graph III thereof, it is visible that the stroke of the displacement piston can even be shifted into the negative range (curve 41), leading to a further reduction of the displacement volume (cf. il-lustration II in Fig. 11d), and thus to a further power reduction, an adjustment according to Fig. 11d result-ing in a power reduction to 6.7 kW, cf. also the p-V
diagram I in Fig. 11d.
Fig. 12 shows a view of a ~3-Stirling engine 50 with an arrangement 1 for the controlled conversion of linear movements, wherein fresh air is introduced via two blowers 51, via a duct 19, into a combustion space 18, which fresh air is heated via a heat exchanger 20 with the assistance of the heat of the waste gas sup-plied via duct 21. The waste gas supplied to the heat exchanger 20 subsequently leaves the (3-Stirling engine 50 towards the environment via ducts 22.
In the partially broken away side view of the (3-Stirling engine 50 in Fig. 13, the displacement piston 4 and a working piston 52 can be seen. The power pro-duced by the ~i-engine 50 can be received at the crank-shaft 53.
In Fig. 14, the (3-engine 50 is shown in which the displacement piston 4 and the working piston 52 are provided in a shared cylinder 54, whereby in theory it is possible for approximately the entire gas mass to be in the hot space 55 during the expansion phase, and in the cold space 56 during the compression phase, respec-tively. Both, the displacement piston rods 3 and also the working piston rods 3' are connected to the roll-lever 5, the rollers 7' of the roll-lever 5' which are associated with the displacement piston rods 3 being rigidly arranged. On the other hand, the rollers 7 which are associated with the working pistons 52 are arranged to be displaceable with the assistance of a connecting link guide 57. For this purpose, a disk 59 including two spiral-shaped recesses 58 is provided in which the ends 13' of the linkages 13 located opposite the rollers 7 are received. By this, the position of the rollers 7 in the roll-levers 5 can be changed when a plate 60 receiving the ends 13' is rotated. With the help of the roll-levers 5, 5', thus a discontinuous movement of the displacement pistons 4 and of the work-ing pistons 52 is achieved, whereby the thermal circle process can be passed in a more ideal manner as com-pared to a sine-shaped piston movement. By this, the mechanical efficiency obtainable is substantially in-creased. With the assistance of the connecting link guide 57 for adjusting the position of the roller 7 of lever 5, thus, an embodiment of simple construction for a dynamic stroke change can be obtained, particularly allowing for a nearly efficiency-neutral and rapid power regulation.
With the wave-type surface sections 23, as large heat exchanger surfaces as possible are obtained (cf.
in this regard the description of Fig. 6). To cool the wave-type surface section of the working piston 52, supply and drain ducts for a coolant (not illustrated) are provided in bath working piston rods 3', which coolant flows through both working piston rods 3'. Oth-erwise, the working piston 52 is constructed like the displacement piston 4 according to Figs. 9 and 10 and therefore need not be further described.
In Fig. 15, a ~3-Stirling engine 50 according to Fig. 14 is shown, yet the position of the rollers 7 in the roll-levers 5 has been changed by aid of the con-necting link means 57. In this manner, a substantially efficiency-neutral and, moreover, rapid power regula-tion of the (3-engine 50 can occur (in this respect, cf.
the graphs of Figs. 19a to 19d).
With the ~i-Stirling engine 50 shown in Fig. 16, the rollers 7 of the roll-lever 5 are in an inner ex-treme position, resulting in a power-minimizing posi-tion of the rollers 7. For this purpose, the ends 13' are inserted in spiral-shaped connecting links 58 of disk 59 as far as to an inner stop. The power minimiza-tion resulting therefrom can be seen from the graphs shown in Fig. 19d.
In Fig. 17 a perspective, broken away view of the ~i-Stirling engine according to Figs. 12 to 16 is shown, wherein, in particular, the compact arrangement of the roll-levers 5 and of the heat exchanger 20 are visible.
With the help of a linear crank 61, the linear move-ments introduced by the driven rods 8 of the arrange-ments 1 are converted into a rotational movement of the crankshaft 53.
As can be seen from the exploded illustration of Fig. 18, only one centrally arranged displacement pis-ton rod 3 is provided for the displacement piston 4, whereas the working piston 52 is connected to the roll-levers 5 via the two laterally arranged working piston rods 3' via connecting rods 2 (cf. Fig. 15).
In Figs. 19a to 19d four different adjustments of the position of the roller 7 supporting the roll-lever 5 are each shown in four graphs, in accordance with the -Stirling engine 50 shown in Figs. 12 to 18. There, each one of Figs. 19a to 19d includes a p-V-diagram I, a graph II of the changing volumes during a complete reciprocation of the working piston and of the dis-placement piston 52, 4, respectively, a graph III of the piston positions of the working piston 52 as well as of the displacement piston 4 over a complete cycle, and a graph IV of the course of the torque of a single cylinder-~-Stirling engine, a two-cylinder-~-engine ac-cording to Figs. 12 to 18, and a four-cylinder-~-en-gine.
From Fig. 19a it can be seen that a very high thermal efficiency results at the position of the roller 7 in the lever 5 according to Fig. 14, wherein according to the computer-simulated p-V-course in a two-cylinder ~-engine according to Figs. 12 to 18, a power of approximately 159 kW will result.
From graph II, it can be seen from the course 64 of the displacement piston (VK) 4 and from the course 65 of the working piston (AK.) 52 that in the adjusted position shown in Fig. 14, the entire volumes of the working piston 52 and of the displacement piston 4 are utilized. Moreover, from the pressure course 66 it can be seen that no excessive pressure peaks are produced, whereby advantageously no excessive demands are made on the mounting of roller 7.
In accordance with the complete utilization of the working piston volume and of the displacement piston volume, respectively, according to graph II, it can be seen from graph III, by way of the course 67 of the po-sition of the displacement piston and the course 68 of the position of the working piston that both pistons execute a maximum stroke.
By way of graph IV it can be recognized that by doubling the number of cylinders of the ~-Stirling en-gine, a more even course of the torque can be attained.
Accordingly, the course 69 of the torque of the single-cxlinder-~-engine has the highest amplitude, the two-cylinder-~-Stirling,engine 50 shown in Figs. 12 to 18 has an already more even course 68 of the torque, and with the help of a four-cylinder-~-Stirling engine a relatively uniform course 71 of the torque can be achieved.
In Figs. 19b, 19c, graphs pertaining to intermedi-ate positions of the roller 7 of the roll-lever 5 are shown, wherein these positions can be adjusted in a simple manner with the help of connecting link guides 57. Depending on the position of the rollers 7, the power of the ~-Stirling engine 50 will decrease, this also being visible from the graphs II, III of Figs.
19b, 19c, due to the decrease of the working piston stroke 68 and, thus, to a reduction of the working pis-ton volume 65. According to the computer-simulated p-V-course 63 according to Fig. 19b, this will result in a power of approximately 73 kW, and according to Fig.
19c, in a power of approximately 21 kW.
In Fig. 19d, the corresponding graphs I, II, III, IV pertaining to the power-minimizing adjustment of the rollers 7 illustrated in Fig. 16 are shown. In this po-sition, merely a power of approximately 4 kW will be achieved. In graph II it is shown that the working pis-ton volume 65 is greatly reduced as compared to the maximum power position illustrated in Fig. 19a, since -as visible in Fig. 19d - the maximum stroke 69 of the working piston 52 is greatly reduced. Of course, as is visible from Fig. 4, reduced torques will result with single, two and also four-cylinder-a-engines.
In Figs. 20 and 21, a double-active four-cylinder Stirling engine 72 comprising arrangements 1 for the controlled conversion of linear movements is shown.
There, also roll-levers 5 with adjustable rollers 7 are shown as pivot points for a power adjustment, working and displacement pistons being combined in one unit 73 in this Stirling engine 72 of particular simple con-struction. Due to this simple construction, there is a lower mechanical efficiency as compared to the ~i-en-gine, and also the power regulation will cause addi-tional losses in efficiency. The transmission of movement in this instance is effected via the drive rods 8 with the assistance of a conventional crank 74.
Of course, the arrangement 1 can also be used to control the power of any other Stirling engine.
Depending on what type of drive unit is provided for a rotary drive, there are many possible ways of controlling the power of the rotary drive. In combus-tion engines, the power can be controlled very well via the fuel supply, whereas, e.g., in Stirling engines a power control without a loss in efficiency has been a great problem for quite some time. For controlling the power of Stirling engines it has been known to change the clearance volumes, on the one hand, and to change the pressure of the working gas, on the other hand, wherein, however, losses in efficiency, or relatively long reduction times, respectively, occur with both types of power control.
From US 3 886 744 A, e.g., a power control system for a Stirling engine is known in which the inlet pres-sure of the hot air is controlled via an annular con-trol element which opens or closes the inlet depending on the differential pressure present; this has the dis-advantage that a very complex construction is provided and that the efficiency of the Stirling engine declines as a consequence of the pressure control.
From US 2 873 611 A, a combustion engine is known in which the stroke of a piston can be changed with the assistance of a circular-arc-shaped lever arm, and thus the power of the driven-side crank can be adjusted. For this purpose, the lever arm has a connecting link guide in which a connecting head is slidably mounted. Since, however, in combustion engines numerous other advanta-geous possibilities are available for an efficient power control, such an arrangement is not suitable in combustion engines.
The invention has as its object to provide a Stir-ling engine of the initially defined type with which a rapid power control is possible without lowering its efficiency.
The Stirling engine according to the invention and of the initially defined type is characterized in that for a power control by means of the transmission of the linear movement of a drive part into the linear move-ment~of a driven part, a lever articulately connected to the drive part and.the driven part is provided, which lever has an associated displaceable pivot point, the bearing point of the lever traveling on the pivot point according to a curve during the movement trans-mission. This curve may have any shape desired - de-pending on the requirements of the movement transmission and on the type of the respective Stirling engine.
. Since the theoretical power of a Stirling engine -considering an isothermal expansion and compression -can be expressed by P-(I-T)~*~ y~",~*P,~ S *sin0 , with 60 I+ I-62 P...... power i...... temperature ratio between compression space and expansion space, n...... number of revolutions (U/min]
VE,",~,~... maximum volume of the expansion space V~.~...maximum volume of the compression space Pm..... effective mean pressure 8...... pressure ratio of engine and wsin ~p ~...tan0= , r + wcos tp with cp = phase angle between working piston and dis-placement piston, and w= ~~"'~ the ratio of the maximum volumes of compres-E,max sion and expansion, as well as T= ~~ the t emperature E
ratio between compression volume and expansion volume, a power control can be carried out by means of the lever arrangement according to the characterizing part of claim 1 without any losses in efficiency, since preferably the maximum compression volume V~,~ and, thus, 'the pressure ratios 8 of the engine can be con-trolled very well.
By adjusting the pivot point on which the lever or its bearing point, respectively, travel during the movement transmission, thus the velocity and the accel-eration of the driven part and a change in the maximum volumes of the compression space caused thereby can be obtained in a very simple way, whereby the power of the Stirling engine can be controlled.
For realizing the change of the bearing point of the lever during the movement transmission with a sim-ple construction, it is advantageous if the lever has a connecting link defining the given curve, which con-necting link slides over the pivot point, e.g. via a roller defining this pivot point, during the movement transmission.
For a well-defined power control of the Stirling engine it has proven particularly advantageous if the curve or connecting link has the shape of a circular arc; yet other curve shapes are, of course, also con-ceivable for certain purposes of use, ~.g, two tangen-tially connected circular arc segments, or an elliptical shape.
To allow. for a simple adjustment of the pivot point, it is advantageous if the pivot point is ar-ranged on a pivot arm.
Shifting of the pivot point can be realized in a structurally particularly simple manner if the pivot arm is connected to an adjustment device.
To equally adjust each point of rotation of two levers - in case at least two cylinders are used, it is advantageous if the adjustment device is connected to a pivot arm via one linkage each and is symmetrically provided between at least two levers.
For a simple configuration of the adjustment de-vice in terms of construction, it is suitable if a spindle drive is provided as the adjustment device.
If a connecting link guide is provided in which the end of the linkage arranged opposite the pivot arm is displaceably and fixably received, the position of the pivot~arm can be changed in a simple and quick man-ner and thus, the power of the Stirling engine can be adjusted.
In a Stirling engine with a double-active working cylinder, in which the movement of the working piston occurs in a sine-shape, it is advantageous if the dis-placement piston is associated with the lever for a power control, whereby a dynamic stroke change as well as a discontinuous movement of the displacement piston will occur.
In a ~-Stirling engine, with which in general higher mechanic efficiencies are obtained than with the remaining types of Stirling engines, the displacement piston and the working piston are located in a common cylinder, whereby, in theory, it is possible for,the entire gas mass to be located in the hot space during the expansion phase and to be located in the cold space during the compression phase. For an efficiency-neutral power control it is then advantageous if the working piston is associated with the lever with a displaceable pivot point, and the displacement lever is associated with a lever with a non-displaceable pivot point.
In a double-active engine, in which the working piston and the displacement piston form one unit for the purpose of a simple construction of the Stirling engine, this unit is associated with the lever for an advantageous power control.
For a reliable movement of the displacement piston and of the working piston, respectively, it is suitable if the drive part is articulately connected to a piston rod which is linearly guided in a straight-line guide and connected to the displacement piston or to the working piston, respectively.
For the required heat exchange to the working gas between the heater and cooler surfaces, respectively, it is suitable if the displacement piston on both sides and the working piston on one side thereof has a wave-shaped section capable of engaging in the neighboring heater or cooler surfaces, respectively. In this man-ner, substantially larger surfaces can get into contact with the working gas, as compared to plane surfaces. As regards a high strength of the displacement piston, it is suitable if the lamella-type wave-shaped sections of the displacement piston are arranged to be turned by 90° relative to each other. Also for a high strength it is advantageous if the lamella-type thin-walled wave-shaped sections of the working piston or heater head, respectively, are supported by stiffening ribs at the burner side and at the coolant side, respectively. An integration of heater-, regenerator- and cooler-sur-faces directly into the working space is particularly advantageous in terms of efficiency and of minimizing the detrimental volume of a Stirling engine.
Instead of cooperating at the driven side with a conventional crankshaft, it may be advantageous in terms of the kinematics for a maximum approach to the ideal circle process, if the linear movement of the driven part is converted into a rotational movement by means of a connecting link which serves as a crank.
In the following, the invention will be described in more detail by way of preferred exemplary embodi-ments illustrated in the drawings to which, however, it shall not be restricted. In detail, in the drawings, Fig. 1 shows a schematic view of an arrangement for the controlled conversion of linear movements, wherein a drive part, the linear movement of which is converted via a lever whose bearing point travels on the pivot point according to a curve, is in its lower end position;
Fig. 2 shows a view of an arrangement according to Fig. 1, wherein the drive part is in a middle, or zero position, respectively;
Fig. 3 shows a view of the arrangement according to Figs. 1 and 2, wherein the drive part is in an upper end position;
Fig. 4 shows a view of a Stirling engine with two displacement units and one arrangement each for con-trolling the reciprocating movement of a displacement piston;
Fig. 5 shows a side view of the Stirling engine according to arrow V of Fig. 4;
Fig. 6 shows a sectional representation according to line VI-VI of Fig. 5;
Fig..7 shows a perspective view of the Stirling engine according to Figs. 4 to 6;
Fig. 8 shows an exploded view of a displacement unit of the Stirling engine with cooler and heater sur-faces, respectively, which have a wave-shaped section;
Fig. 9 shows a perspective view of a displacement piston for a reciprocating movement in a displacement unit according to Fig. 8;
Fig. 10 shows an exploded view of the displacement piston according to Fig. 9;
Figs. 11a to 11d are different graphs regarding the Stirling engine illustrated in Figs. 4 to 7, a dif-ferent position of the pivot point of the lever for controlling the reciprocating movement of the drive _ 8 _ part being shown in each case;
Fig. 12 shows a view of a (3-Stirling-two-cylinder engine comprising two displacement units and one device each for controlling, over time, the stroke movement and the movement of a working piston;
Fig. 13 is a partially broken away side .view of the (3-engine according to Fig. 12;
Fig. 14 is a sectional representation according to line XIV-XIV of Fig. 13, with the pivot points being at their maximum power position and the working pistons reaching their maximum stroke;
Fig. 15 is a side view of the ~i-engine according to Fig. 14, with the pivot points being in an interme-diate position;
Fig. 16 shows a view of the (3-engine according to Figs. 14 and 15, with the pivot points being in a power-minimizing position;
Fig. 17 shows a perspective view of the sectional representation according to Figs. 14 to 16;
Fig. 18 shows an exploded view of the ~i-engine ac-cording to Figs. 12 to 17;
Figs. 19a to 19d show different graphs regarding the (3-engine illustrated in Figs. 12 to 18, each graph showing a different position of the pivot point of the lever for controlling the receiprocating movement of the drive shaft;
_ g _ Fig. 20 shows a view of a double-active Stirling engine with an arrangement for the controlled conver-sion of linear movements; and Fig. 21 shows a sectional representation according to line XXT-XXI of Fig. 20.
In Figs. 1 to 3, an arrangement 1 for the con-trolled conversion of linear movements is shown, wherein a connecting rod 2 working as drive part is provided which is articulately connected to a piston rod 3 of a displacement piston 4 of a Stirling en-gine (cf. Fig. 6). Via an axle 2', the connecting rod 2 furthermore is articulately connected to a lever 5 which has a given control curve in the form of a con-necting link 6 in which a roller 7 freely rotatable about an axle 7' and serving as a pivot point for lever (subsequently, therefore, also being termed "roll-lever") is provided. The other end of the lever 5, which is, substantially angled by 90°, is articulately connected about an. axis 8' to a driven rod 8 to which the linear movement of the displacement piston rod 3 is transmitted. The driven rod 8 in turn is linearly mounted, yet turned by 90° with a view to the linear movement of the displacement piston rod 3.
As is visible from Figs. 1 to 3, the bearing point of lever 5, depending on the position of the displace-~ment piston rod 3, or of the connecting rod 2, respec-tively, moves along a curve 6' defined by the connecting link 6.
One of the essential parameters for determining the transmission of movement between the displacement piston rod 3 and the driven rod 8 is the distance LR
(cf. Fig.2) between the axis of rotation 8' between be lever 5 and the driven rod 8 and the axis of rotation 7' on which roller 7 is rotatably mounted. This dis -tance LR can be expressed as LR(x)= y~+(zl+x)Z
wherein x is the horizontal position of the axis of ro-tation 8' (and, thus, the displacement of the driven rod 8), y is the vertical distance between the axes of rotation 8' and 7', and z~ is the horizontal distance between the two axes of rotation 8', 7'.
Furthermore, the angle a enclosed by the imaginary connecting line between the axes of rotation 7', 8' to the vertical line, is important for the transmission of movement, and this angle a can be expressed by zi+x a(x)=~~ , y~
whereas the change ~a of this angle can be indicated as z~+x z1 d a = arctan - arctan - , y, v, with the intermediate or zero position shown in Fig. 2, in which one leg of the lever 5 is horizontal and the other leg of lever 5 ~.s vertical, being taken as a ref-- 1I. -erence.
Fur~.hexmore, the angle {i between the connecting line between the axes of rotation 7', 8' and the con-necting line between the axes of rotation 7', 2' is of importance for the transmission of movement, wherein ~{x)=arccos LR{x)2~a2 2 a2+RZ*LR(x) or y~+z~+a2 ~(0)=arccos , respectively, 2 a2+R2 y~+z~
and 4~=~'(x)-~(~) with R being the adjustable rolling radius of roller 7 and ~ being the vertical distance of the imaginary cen-ter of the rolling radius from the middle line of driven rod 8. Furthermore, the position of the axis of rotation 2' is. of importance, which is dependent on the respective positions of the drive rod, and driven rod, respectively, and thus can be expressed as x'(x)=-LR'*cosc~{x)+x and y'(x)=LR'*sincp(x) . respectively, wherein the angle ~, with the assistance of the differ-ence angles ~a and A(i, respectively, can be expressed as fi(x)=Q~(0)-~a-ds , wherein in the intermediate posi-tion ~(0)=arctan R+b and ~ is the horizontal distance between the imaginary roll-circuit center R and the axis 2' in the intermedi-ate position. LR' is the distance between the axes of rotation 8' and 2', and thus can be expressed as LR'= (R+a)2+(R+b)2 With the assistance of the axis of rotation 3' be-tween the displacement piston rod 3 and the connecting rod 2, the position of the displacement piston rod 3 can be expressed as P(x)= IZ-(c+x'(x))2+Y'(x) wherein the axis of rotation in its position shown in Fig. 2 is present in the position p(0)= 12-(c-b-R)2-(a+R) and wherein ,~ represents the length of connecting rod 2 and .~ indicates the horizontal distance of axis 8' in the reference position from the middle axis of the dis-placement piston rod 3.
In Fig. 3, the displacement piston rod 3 is illus-trated in its uppermost position, it being visible that roller 7 comes to rest against the rim of connecting link 6 neither in this extreme position nor in the ex-treme position illustrated in Fig. 1.
In Fig. 4, a Stirling engine 10 comprising ar-rangements 1 for the controlled linear movement trans-mission from a respective displacement piston rod 3 to an associated driven rod 8 is illustrated. The Stirling engine 20 has two displacement units 11 in which one displacement piston 4 each is reciprocated. The move-ment described by the respective lever 5 can be changed by adjusting the position of roller 7 which is adjust-able via a pivot arm 12. For adjusting the position of pivot arm 12, one linkage 13 each is provided which is adjustable with the assistance of a common spindle drive 14 via an adjustment wheel 15. By upward rotation of the adjustment wheel 15, the position of rollers 7 can be changed such that a power change will result therefrom, as can be seen from Figs. 11a to 11d.
In the Fig. 5 side view of the Stirling engine 10, the working cylinder 16 can be seen which is fed via a duct 17. Via a duct 19 and via a heat exchanger 20, fresh air heated with the assistance of the heat of the waste gas supplied via a duct 21 is introduced for com-bustion purposes info a combustion space 18 (cf. Fig.
6) of the displacement unit 11, which fresh air, after having passed the heat exchanger 20, can escape into the environment via duct 22.
In Fig. 6, a section of the Stirling engine l0 ac-cording to line VI-VI of Fig. 5 is shown; there, a wave-shaped section 23 of the cooler surfaces 24 and heater surfaces 25, respectively, can be seen, with these heat exchanger surfaces 24, 25 possibly being made of ceramics, e.g.. The heater surfaces 25 follow upon the combustion spaces 18, in which one burner 26 each is provided for the heating, or combustion, re-spectively, of the already pre-heated fresh air intro-duced via ducts 19. The displacement piston 4 shifts the working gas between a hot chamber 27 and a cool chamber 28, the middle part 37 of the displacement pis-ton 4 containing the regenerator (cf. Fig. 5).
Furthermore, it can be seen in Fig. 6 that the connecting rod 2 is connected by a hinge 3' guided in a straight-line guide 30 so as to guide the displacement piston rod 3. To transmit the movement from the driven rod 8 to a crankshaft 31 (cf. Fig. 5), a type of crank drive 32 (Fig. 6) is provided.
In Fig. 7, a perspective view of the Stirling en-gine 10 comprising the arrangements 1 associated with the displacement units 11 and provided for the con-trolled transmission of the linear movements of the connecting rods 3 is shown. Furthermore, the adjustment mechanism for the rollers 7 via rods 13 can be seen which, by rotating the adjustment wheel 15, allows for an adjustment of the position of the rollers 7, whereby in turn a power control of the Stirling engine 10 by the altered reciprocating movement of the displacement piston 4 is provided.
_ 15. _ In Fig. 8, an exploded view of the displacement unit 11 is shown. In the cooler lid region, substan-tially the straight-line guide 30 for receiving the ar-ticulated connection between the displacement piston rod 3 and the connecting rod 2 is shown, which straight-line guide is screwed to the cooler-side lid 33. The heat exchanger surface 24 provided for cooling is connected to the cooler-side lid 33 via several screws 34. Furthermore, a cylinder 35 is provided on which the duct 17 is provided for the spatial connec-tion with the working cylinder 16. Just like the cool heat exchanger surface 24, the hot heat exchanger sur-face 25 has a wave-type surface section on either side for stability purposes which preferably is rotated by 90°, so as to obtain as large a surface as possible, which enhances a heat exchange between the hot and the cool surface, respectively, and the displacement cham-ber.
From Figs. 9 and 10 it can be seen that a roller 36 is provided at the connecting-rod-side end of the displacement piston rod 3, which roller slides in the straight-line guide 30, whereby the linear guidance of the displacement piston 4 is ensured. The displacement piston 10 consists of three individual parts, section halves 38 each being screwed to a regenerator disc 37, which section halves have the aforementioned wave-type section provided for mutual engagement with the wave-type section of the heat exchanger surfaces 24 and 25, respectively. The regenerator disk 37 which may, e.g., be made of ceramics, has slot-shaped cavities 37' in which a regenerator material, e.g. sintered steel wool having a porosity of approximately 60-70~, is embedded.
Figs. 11a to 11d show, in four graphs each, four different adjustments of the position of the roller 7 supporting the roll-lever 5. Each one of Figs. 11a tb 11d includes a p-V diagram I, a graph II of the chang-ing volumes during a complete reciprocation of the working piston and of the displacement piston, respec-tively, a graph III of the piston positions of the working piston as well as of the displacement piston over a complete cycle, and a standardized illustration IV of the piston positions of the working and displace-ment pistons as regards their extreme positions made possible in accordance with the adjustment of the roller 7.
From Fig. 11a it can be seen that a power increase is possible with a position of the roller 7 pivoted very much out of the vertical, in which the phase shift between the course 40 of the working piston and the course 41 of the displacement piston has been reduced from 90° to approximately 85° (cf. illustration III), whereby a maximum pressure 45 (cf. diagram I) which is the same as compared to a normal sine course 42 is at-tained, and the power in the example illustrated in Fig. 11a can be increased to 102.6 kW (cf. computer-simulated p-V-course 44 with roll-lever control) as compared to 97.6 kW (cf. computer-simulated p-v-course 43) with a conventional sine course of the displacement piston 42.
From graph II it can be seen from the course of the working volume 46 and of the displacement volume 47 that in the adjusted position illustrated in Fig. 11a, the entire volumes of the working and displacement pis-tons are utilized. Moreover, in the standardized graphs IV of Figs. 11a to 11d, the relative piston course 48 of the working piston and the relative piston course 49 of the displacement piston are illustrated.
At an upward rotation of the adjustment wheel 15, by which the roller 7 is displaced towards a vertical position, as is visible from Figs. 11b to 11d, depend-ing on the position of the roller 7, the maximum stroke of the displacement piston 4 is reduced (cf. graphs III
in Figs. 11b and 11c), whereby the active volume of the displacement piston 4 is reduced (cf. graphs II), and thus an efficiency-neutral power control of the Stir-ling engine 10 is achieved.
From Fig. 11d, in graph III thereof, it is visible that the stroke of the displacement piston can even be shifted into the negative range (curve 41), leading to a further reduction of the displacement volume (cf. il-lustration II in Fig. 11d), and thus to a further power reduction, an adjustment according to Fig. 11d result-ing in a power reduction to 6.7 kW, cf. also the p-V
diagram I in Fig. 11d.
Fig. 12 shows a view of a ~3-Stirling engine 50 with an arrangement 1 for the controlled conversion of linear movements, wherein fresh air is introduced via two blowers 51, via a duct 19, into a combustion space 18, which fresh air is heated via a heat exchanger 20 with the assistance of the heat of the waste gas sup-plied via duct 21. The waste gas supplied to the heat exchanger 20 subsequently leaves the (3-Stirling engine 50 towards the environment via ducts 22.
In the partially broken away side view of the (3-Stirling engine 50 in Fig. 13, the displacement piston 4 and a working piston 52 can be seen. The power pro-duced by the ~i-engine 50 can be received at the crank-shaft 53.
In Fig. 14, the (3-engine 50 is shown in which the displacement piston 4 and the working piston 52 are provided in a shared cylinder 54, whereby in theory it is possible for approximately the entire gas mass to be in the hot space 55 during the expansion phase, and in the cold space 56 during the compression phase, respec-tively. Both, the displacement piston rods 3 and also the working piston rods 3' are connected to the roll-lever 5, the rollers 7' of the roll-lever 5' which are associated with the displacement piston rods 3 being rigidly arranged. On the other hand, the rollers 7 which are associated with the working pistons 52 are arranged to be displaceable with the assistance of a connecting link guide 57. For this purpose, a disk 59 including two spiral-shaped recesses 58 is provided in which the ends 13' of the linkages 13 located opposite the rollers 7 are received. By this, the position of the rollers 7 in the roll-levers 5 can be changed when a plate 60 receiving the ends 13' is rotated. With the help of the roll-levers 5, 5', thus a discontinuous movement of the displacement pistons 4 and of the work-ing pistons 52 is achieved, whereby the thermal circle process can be passed in a more ideal manner as com-pared to a sine-shaped piston movement. By this, the mechanical efficiency obtainable is substantially in-creased. With the assistance of the connecting link guide 57 for adjusting the position of the roller 7 of lever 5, thus, an embodiment of simple construction for a dynamic stroke change can be obtained, particularly allowing for a nearly efficiency-neutral and rapid power regulation.
With the wave-type surface sections 23, as large heat exchanger surfaces as possible are obtained (cf.
in this regard the description of Fig. 6). To cool the wave-type surface section of the working piston 52, supply and drain ducts for a coolant (not illustrated) are provided in bath working piston rods 3', which coolant flows through both working piston rods 3'. Oth-erwise, the working piston 52 is constructed like the displacement piston 4 according to Figs. 9 and 10 and therefore need not be further described.
In Fig. 15, a ~3-Stirling engine 50 according to Fig. 14 is shown, yet the position of the rollers 7 in the roll-levers 5 has been changed by aid of the con-necting link means 57. In this manner, a substantially efficiency-neutral and, moreover, rapid power regula-tion of the (3-engine 50 can occur (in this respect, cf.
the graphs of Figs. 19a to 19d).
With the ~i-Stirling engine 50 shown in Fig. 16, the rollers 7 of the roll-lever 5 are in an inner ex-treme position, resulting in a power-minimizing posi-tion of the rollers 7. For this purpose, the ends 13' are inserted in spiral-shaped connecting links 58 of disk 59 as far as to an inner stop. The power minimiza-tion resulting therefrom can be seen from the graphs shown in Fig. 19d.
In Fig. 17 a perspective, broken away view of the ~i-Stirling engine according to Figs. 12 to 16 is shown, wherein, in particular, the compact arrangement of the roll-levers 5 and of the heat exchanger 20 are visible.
With the help of a linear crank 61, the linear move-ments introduced by the driven rods 8 of the arrange-ments 1 are converted into a rotational movement of the crankshaft 53.
As can be seen from the exploded illustration of Fig. 18, only one centrally arranged displacement pis-ton rod 3 is provided for the displacement piston 4, whereas the working piston 52 is connected to the roll-levers 5 via the two laterally arranged working piston rods 3' via connecting rods 2 (cf. Fig. 15).
In Figs. 19a to 19d four different adjustments of the position of the roller 7 supporting the roll-lever 5 are each shown in four graphs, in accordance with the -Stirling engine 50 shown in Figs. 12 to 18. There, each one of Figs. 19a to 19d includes a p-V-diagram I, a graph II of the changing volumes during a complete reciprocation of the working piston and of the dis-placement piston 52, 4, respectively, a graph III of the piston positions of the working piston 52 as well as of the displacement piston 4 over a complete cycle, and a graph IV of the course of the torque of a single cylinder-~-Stirling engine, a two-cylinder-~-engine ac-cording to Figs. 12 to 18, and a four-cylinder-~-en-gine.
From Fig. 19a it can be seen that a very high thermal efficiency results at the position of the roller 7 in the lever 5 according to Fig. 14, wherein according to the computer-simulated p-V-course in a two-cylinder ~-engine according to Figs. 12 to 18, a power of approximately 159 kW will result.
From graph II, it can be seen from the course 64 of the displacement piston (VK) 4 and from the course 65 of the working piston (AK.) 52 that in the adjusted position shown in Fig. 14, the entire volumes of the working piston 52 and of the displacement piston 4 are utilized. Moreover, from the pressure course 66 it can be seen that no excessive pressure peaks are produced, whereby advantageously no excessive demands are made on the mounting of roller 7.
In accordance with the complete utilization of the working piston volume and of the displacement piston volume, respectively, according to graph II, it can be seen from graph III, by way of the course 67 of the po-sition of the displacement piston and the course 68 of the position of the working piston that both pistons execute a maximum stroke.
By way of graph IV it can be recognized that by doubling the number of cylinders of the ~-Stirling en-gine, a more even course of the torque can be attained.
Accordingly, the course 69 of the torque of the single-cxlinder-~-engine has the highest amplitude, the two-cylinder-~-Stirling,engine 50 shown in Figs. 12 to 18 has an already more even course 68 of the torque, and with the help of a four-cylinder-~-Stirling engine a relatively uniform course 71 of the torque can be achieved.
In Figs. 19b, 19c, graphs pertaining to intermedi-ate positions of the roller 7 of the roll-lever 5 are shown, wherein these positions can be adjusted in a simple manner with the help of connecting link guides 57. Depending on the position of the rollers 7, the power of the ~-Stirling engine 50 will decrease, this also being visible from the graphs II, III of Figs.
19b, 19c, due to the decrease of the working piston stroke 68 and, thus, to a reduction of the working pis-ton volume 65. According to the computer-simulated p-V-course 63 according to Fig. 19b, this will result in a power of approximately 73 kW, and according to Fig.
19c, in a power of approximately 21 kW.
In Fig. 19d, the corresponding graphs I, II, III, IV pertaining to the power-minimizing adjustment of the rollers 7 illustrated in Fig. 16 are shown. In this po-sition, merely a power of approximately 4 kW will be achieved. In graph II it is shown that the working pis-ton volume 65 is greatly reduced as compared to the maximum power position illustrated in Fig. 19a, since -as visible in Fig. 19d - the maximum stroke 69 of the working piston 52 is greatly reduced. Of course, as is visible from Fig. 4, reduced torques will result with single, two and also four-cylinder-a-engines.
In Figs. 20 and 21, a double-active four-cylinder Stirling engine 72 comprising arrangements 1 for the controlled conversion of linear movements is shown.
There, also roll-levers 5 with adjustable rollers 7 are shown as pivot points for a power adjustment, working and displacement pistons being combined in one unit 73 in this Stirling engine 72 of particular simple con-struction. Due to this simple construction, there is a lower mechanical efficiency as compared to the ~i-en-gine, and also the power regulation will cause addi-tional losses in efficiency. The transmission of movement in this instance is effected via the drive rods 8 with the assistance of a conventional crank 74.
Of course, the arrangement 1 can also be used to control the power of any other Stirling engine.
Claims (16)
1. A Stirling engine (10, 50, 72) comprising at least one working piston (52) and at least one displacement piston (4), characterized in that for a power control by means of the transmission of the linear movement of a drive part (2) into the linear movement of a driven part (8), a lever (5) articulately connected to the drive part and to the driven part (2, 8) is provided, which lever has an associated displaceable pivot point (7), the bearing point of the lever (5) travelling on the pivot point (7) according to a curve during the movement transmission.
2. A Stirling engine according to claim 1, character-ized in that the lever (5) has a connecting link (6) defining the given curve, which connecting link slides over the pivot point (7), e.g. via a roller defining this pivot point (7), during the movement transmission.
3. A Stirling engine according to claim 1 or 2, char-acterized in that the curve or connecting link (6) has the shape of a circular arc.
4. A Stirling engine according to any one of claims 1 to 3, characterized in that the pivot point (7) is ar-ranged on a pivot arm (12).
5. A Stirling engine according to claim 4, character-ized in that the pivot arm (12) is connected to an ad-justment device (14, 57).
6. A Stirling engine according to claim 5, character-ized in that the adjustment device (14, 57) is con-nected via a linkage (13) each with a pivot arm (12) and is symmetrically provided between at least two lev-ers (5).
7. A Stirling engine according to claim 6, character-ized in that a spindle drive (14) is provided as the adjustment device.
8. A Stirling engine according to claim 6, character-ized in that a connecting link guide (57) is provided as the adjustment device.
9. A Stirling engine according to any one of claims 1 to 8, characterized in that the displacement piston (4) is associated with the lever (5) for a power control.
10. A Stirling engine according to any one of claims 1 to 8, characterized in that the working piston (52) is associated with the lever (5) for a power control.
11. A Stirling engine according to claim 10, charac-terized in that the displacement piston (52) is associ-ated with a lever (5') having a non-displaceable pivot point.
12. A Stirling engine according to any one of claims 1 to 8, characterized in that the working piston (52) and the displacement piston (4) form a unit (73) which is associated with the lever (5).
13. A Stirling engine according to any one of claims 9 to 12, characterized in that the drive part (2) is articulately connected to a piston rod (3, 3').linearly guided in a straight-line guide (30) and connected to the displacement piston (4) and to the working pis-ton (52), respectively.
14. A Stirling engine according to any one of claims 1 to 13, characterized in that the displacement piston (4) on both sides and the working piston (52) on one side thereof has a lamella-type wave-shaped section (23) in neighboring heater and cooler surfaces (24, 25).
15. A Stirling engine according to claim 14, charac-terized in that the lamella-type wave-shaped sec-tions (23) of the displacement piston (4) are arranged turned by 90° relative to each other.
16. A Stirling engine according to any one of claims 1 to 15, characterized in that the linear movement of the driven part (8) is converted into a rotational movement by means of a connecting link (32) which serves as crank.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ATA936/2000 | 2000-05-29 | ||
| AT0093600A AT411844B (en) | 2000-05-29 | 2000-05-29 | HOT GAS ENGINE |
| PCT/AT2001/000169 WO2001092708A1 (en) | 2000-05-29 | 2001-05-29 | Stirling engine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2405174A1 true CA2405174A1 (en) | 2002-10-07 |
Family
ID=3683251
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002405174A Abandoned CA2405174A1 (en) | 2000-05-29 | 2001-05-29 | Stirling engine |
Country Status (14)
| Country | Link |
|---|---|
| US (1) | US6729131B2 (en) |
| EP (1) | EP1285160B1 (en) |
| JP (1) | JP2003535262A (en) |
| KR (1) | KR100743954B1 (en) |
| CN (1) | CN1208544C (en) |
| AT (2) | AT411844B (en) |
| AU (2) | AU7372201A (en) |
| BR (1) | BR0111662A (en) |
| CA (1) | CA2405174A1 (en) |
| DE (1) | DE50113863D1 (en) |
| EA (1) | EA003980B1 (en) |
| HK (1) | HK1052956B (en) |
| MX (1) | MXPA02011800A (en) |
| WO (1) | WO2001092708A1 (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7484366B2 (en) * | 2003-05-13 | 2009-02-03 | Honda Motor Co., Ltd. | Multistage stirling engine |
| FR2881513B1 (en) * | 2005-02-03 | 2007-04-06 | Sagem | COLD MACHINE OPERATING FOLLOWING THE STIRLING CYCLE |
| CN101463775B (en) * | 2007-12-19 | 2011-06-15 | 孔令斌 | Stirling reversible heat engine |
| US8096118B2 (en) * | 2009-01-30 | 2012-01-17 | Williams Jonathan H | Engine for utilizing thermal energy to generate electricity |
| DE102012107064B4 (en) | 2011-12-17 | 2014-05-22 | Andre Zimmer | Stirling engine |
| MD679Z (en) * | 2013-03-01 | 2014-04-30 | ИНСТИТУТ ЭЛЕКТРОННОЙ ИНЖЕНЕРИИ И НАНОТЕХНОЛОГИЙ "D. Ghitu" АНМ | Stirling cycle-based heat engine |
| WO2015139104A2 (en) * | 2014-03-21 | 2015-09-24 | Hirosi Suzuki | Stirling engine having a delta configuration |
| CN103925110B (en) * | 2014-04-30 | 2015-11-04 | 郭远军 | A kind of V-type high low pressure power equipment and work method thereof |
| USD923573S1 (en) * | 2020-11-22 | 2021-06-29 | Yi Zhang | Stirling engine |
| USD923572S1 (en) * | 2020-11-22 | 2021-06-29 | Yi Zhang | Stirling engine |
Family Cites Families (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US273276A (en) * | 1883-03-06 | Feed-water adjustment for pumps | ||
| US680237A (en) * | 1900-11-12 | 1901-08-13 | Maurice Auguste Eudelin | Motor for automobiles driven by explosion of inflammable vapors. |
| US926564A (en) * | 1907-07-16 | 1909-06-29 | William H Hollopeter | Internal-combustion engine. |
| US1909372A (en) * | 1931-05-06 | 1933-05-16 | Mccollum James Harry Keighley | Variable stroke internal combustion engine |
| US2776573A (en) | 1954-03-01 | 1957-01-08 | Baldwin Lima Hamilton Corp | Variable reciprocating stroke mechanism |
| US2873611A (en) * | 1955-07-01 | 1959-02-17 | Arnold E Biermann | Variable stroke mechanisms |
| US2822791A (en) * | 1955-07-01 | 1958-02-11 | Arnold E Biermann | Variable stroke piston engines |
| GB1266451A (en) * | 1969-02-21 | 1972-03-08 | ||
| US3886744A (en) * | 1974-07-22 | 1975-06-03 | Philips Corp | Power-control system for stirling engines |
| FR2465133A1 (en) * | 1979-09-17 | 1981-03-20 | Bultot Gaston | Force multiplier for speed reducer - has a circular guide reducing travel of lever operated by cam |
| US4346677A (en) * | 1980-09-02 | 1982-08-31 | Nye Norman H | Combustion engine with substantially constant compression |
| US4387566A (en) | 1981-03-11 | 1983-06-14 | Mechanical Technology Incorporated | Independently variable phase and stroke control for a double acting Stirling engine |
| US4392350A (en) * | 1981-03-23 | 1983-07-12 | Mechanical Technology Incorporation | Stirling engine power control and motion conversion mechanism |
| US4553392A (en) * | 1984-12-12 | 1985-11-19 | Stirling Technology, Inc. | Self pressurizing, crank-type Stirling engine having reduced loading of displacer drive linkages |
| US4917066A (en) * | 1986-06-04 | 1990-04-17 | The Trustees Of Columbia University In The City Of New York | Swing beam internal-combustion engines |
| GB2211262B (en) * | 1987-10-20 | 1991-07-24 | David Arthur Pritchard | Reciprocating drive mechanism |
| US4970861A (en) * | 1989-11-07 | 1990-11-20 | Northrop Corporation | Geared rotary-to-linear motion converting system for bidirectional pump drive |
| GB9008522D0 (en) * | 1990-04-17 | 1990-06-13 | Energy For Suitable Dev Limite | Reciprocatory displacement machine |
| US5136987A (en) * | 1991-06-24 | 1992-08-11 | Ford Motor Company | Variable displacement and compression ratio piston engine |
| JP2828935B2 (en) * | 1995-09-19 | 1998-11-25 | 三洋電機株式会社 | Gas compression and expansion machine |
-
2000
- 2000-05-29 AT AT0093600A patent/AT411844B/en not_active IP Right Cessation
-
2001
- 2001-05-29 JP JP2002500089A patent/JP2003535262A/en not_active Withdrawn
- 2001-05-29 CA CA002405174A patent/CA2405174A1/en not_active Abandoned
- 2001-05-29 EP EP01940002A patent/EP1285160B1/en not_active Expired - Lifetime
- 2001-05-29 AT AT01940002T patent/ATE392545T1/en not_active IP Right Cessation
- 2001-05-29 MX MXPA02011800A patent/MXPA02011800A/en active IP Right Grant
- 2001-05-29 AU AU7372201A patent/AU7372201A/en active Pending
- 2001-05-29 KR KR1020027014378A patent/KR100743954B1/en not_active IP Right Cessation
- 2001-05-29 WO PCT/AT2001/000169 patent/WO2001092708A1/en active IP Right Grant
- 2001-05-29 US US10/276,958 patent/US6729131B2/en not_active Expired - Fee Related
- 2001-05-29 EA EA200201297A patent/EA003980B1/en not_active IP Right Cessation
- 2001-05-29 BR BR0111662-2A patent/BR0111662A/en active Search and Examination
- 2001-05-29 CN CNB018100651A patent/CN1208544C/en not_active Expired - Fee Related
- 2001-05-29 DE DE50113863T patent/DE50113863D1/en not_active Expired - Fee Related
- 2001-05-29 AU AU2001273722A patent/AU2001273722B2/en not_active Ceased
-
2003
- 2003-07-18 HK HK03105200.2A patent/HK1052956B/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| WO2001092708A1 (en) | 2001-12-06 |
| BR0111662A (en) | 2003-05-20 |
| MXPA02011800A (en) | 2003-04-25 |
| EP1285160B1 (en) | 2008-04-16 |
| ATE392545T1 (en) | 2008-05-15 |
| EP1285160A1 (en) | 2003-02-26 |
| ATA9362000A (en) | 2003-11-15 |
| HK1052956B (en) | 2008-11-28 |
| JP2003535262A (en) | 2003-11-25 |
| EA200201297A1 (en) | 2003-04-24 |
| HK1052956A1 (en) | 2003-10-03 |
| DE50113863D1 (en) | 2008-05-29 |
| CN1441875A (en) | 2003-09-10 |
| EA003980B1 (en) | 2003-12-25 |
| CN1208544C (en) | 2005-06-29 |
| AU7372201A (en) | 2001-12-11 |
| US6729131B2 (en) | 2004-05-04 |
| KR100743954B1 (en) | 2007-07-30 |
| AU2001273722B2 (en) | 2004-10-07 |
| AT411844B (en) | 2004-06-25 |
| US20030167766A1 (en) | 2003-09-11 |
| KR20030005302A (en) | 2003-01-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |