US2250200A - Crankcase ventilating system - Google Patents

Description

July 22, 1941. w. w. LowrHER CRANKCASE VENTILATING SYSTEM Filed Hay 27, 1938 2 Sheets-Sheet l July 22, 1941.

. W. W. LOWTHER CRANKCASE VEINTILTING SYSTEM Filedv May 27, 1938 2 Sheets-Sheet 2 Patented July 22,v 1941 2,250,200 o Fries caANxcAsn vaN'rmA'rmG srsm Wilfred W. Lowther, St. Paul, Minn., assigner to Donaldson Company, Inc.. St. Foul, Minnw'a corporation of Delaware Y Application May'Z'Z, 1938, Serial No. 210,400

1s claims. (ci. 12a-.119)

This invention relates to inter-nal combustion engines and more particularly to a novel system of obtaining a uni-directional flow of air, under Y pressure above that of atmosphere, outwardly from the intake manifolds of internal combustion engines, wherein the predominate pressure is above that of atmosphere. While the general principles involved in the system broadly referred to above lare adapted for a wide variety of applications, they most, readily adapt themselves for use in the ventilation of crank cases` of internal combustion engines and, insofar as the present application is concerned, the description thereof A will be limited to two such adaptions.

The crank-case Ventilating system of my plished by extending asuitable conduit between the engines intake conduit, ,at a point on the atmosphere side of the intake valve, and the crank-case and interposing inthatconnection or conduit a one-way check valve permitting free ilow of air from the enginesintake' conduitto the crank-case under intermittent air-ram effects or pressure surges but which prevents retum now of air from the crank-case under alternate lower pressure or partial vacuum conditions ofthe cngines intake. If airis to be circulated through Y the crank-case as a result of these pressure surges prior Patent No. 2,060,883 of November 17, 1938 hasv worked out in practice with a very high degree of success in connection with gasoline `engines, but that system, being dependent for its.

use of the intermittent pressure surges produced l in the engines intake valve or valves to produce or aid in producing a forced circulation of air from the intake conduit through the engines crank-case and, hence, is not restricted to use with engines having restriction-producing means such as throttle valves or carburetors ln the intake.

As is well known, under operation condition of an internal combustion engine, the predominating pressure in the intake duct leading to the engines combustion chamber is below atmospheric pressure, or in other words, is a partial vacuum. What is also a fact, although not so widely recognized, is that under the intermittent closing of the intake valve to any cylinder of an engine' there is produced, for each valve closure, a pressure surge which is momentarily much greater than the predominating or mean average presy inafter be referred to as such.

In accordancewith the instant invention this intermittent air-ram effect in the intake conduit is harnessed to create or aidin. creating a forced movement of air from the engines air intake conduit to the crank-case. Preferably this is accomthere must, of course, be provided an air outlet trom the crank-case and although this may be direct to atmosphere, such crank-case outlet is preferably connected back'to the engines intake where it will be subject to a predominating vacu-v um condition of the engine's intake which will further aid in the circulation o f air through the crank-case. Further, since it is desired to keep the crank-case as free as possible from dust and other foreign substance and since enginesof the present day are almostuniversally equipped with air cleaners in their air intakes, the air supplied to the crank-case in the manner above'described can easily be kept free from dirt by making the said connection or connections from the crankcase to the intake conduitv at a point or` points after the intake air cleaner.

In the accompanying drawings like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. 1 is a transverse sectional view through an internal combustion engine incorporating one embodiment of the invention;

Fig. 2 is an enlarged detail view in the side elevation with some parts broken away and some parts shown in section of the .check valve of Fig. 1:

Fig. 3 is .a transverse sectional view taken on the line 3-3 of Fig. 2 and looking upwardly. `in

trated in Figs. 1 and 2 but which may be substituted for the valve disc of Figs. l, 2 and 3;

Fig. 1' is atransverse sectional view similar another embodiment of to Fig. 1 but illustrating the invention: and

Fig. 2' is an enlarged detail view of ythe check s sidered to be of the Diesel or oil burning type.

since the intake conduit thereof incorporates no throttle valve or carburetor. Obviously. the engine illustrated may incorporate any number of cylinders, but, for the purpose of this case, it may :lust as well be considered as a one-cylinder engine.

Of the 'conventional parts of the engine the cylinder block thereof is indicated as an entirety by 5, the cylinder bore thereof by 6, the piston by 1, the crank shaft by 8, the connecting rod by 8, the crank-case by III, the cam shaft by I|,'the intake valve operating'cam by- I2, the cylinder head by I3, the combustion chamber formed in the cylinder head above the cylinder bore 6, by Il, the spring-closed intake valve by I5, the roller tappet assembly by I6, the push rod. by I1, and the intermediately pivoted rocker arm by I8 In accordance withgeneral practice the bottom oi the crank-case I is closed by a removable oil pan I3, containing a suitable body of lubricating oil y, and the valve actuating connections I1 and I8 are enclosed by a removable inspection plate and a-reniovable hood 2|. Alsxzo in accordance with conventional practice, in overhead engines free communication is established between the valve mechanism chamber vwithin the hood 2| and the crank-case In. In

accordance with the present illustration, such communication is established through passages 22, 23 and 24. The cylinder head I3 is provided with an intake port 25 that is controlled by the intake valve I5, and this intake port -25 is connected to atmosphere through a combustion chamber air intake duct 26 having applied therein a suitable air cleaner 21.

vIn accordance with the present illustration the ventilation inlet to the crank-case is made tov one side thereof at 28 and the ventilation outlet from the crank-case is made from the valve mechanism chamber within the hood 2| at 23. The ventilation inlet 28 to the crank-case 'is connected to' the combustion chamber air intake duct 26 at a point intermediate the air cleaner 21 and intake valve I5 by a relatively large area check-valve-equipped crank-case air intake duct 30, and the ventilation outlet in the crank-case is also connected to` the combustion chamber air intake duct 26 at a point intermediate'the air cleaner 21 and intake valve I5. This latter connection between the crank-case and intake duct, however, is preferably made through a relativelylsmall area duct or conduit 3|.

The check valve in the crank-case air inlet duct 30 is indicated as an entirety by 32, and in accordance with the .present illustration, includes a'two-part valvev body 33, which parts are detachably secured together by screws or the like 3l. The upper portion of the valve body is formed with an externally threaded tapered neck that is screw threaded into combustion chamber intake duct 26, and the lower half of the valve body 33 is internally threaded at 36 to facilitate coupling to the conduit 3 3. The bore ofthe upper portion of the `valve body 331s coaxial with but of smaller diameter-than that of the lower valve body so as to form, at the point of joinder of the upper and lower portions of the valve body, a'shoulder 31 that affords a valve seat. In axially spaced relation to the shoulder 31 the for example,'as very light sheet bronze. However, a valve disc made of relatively rm rubber composition has also been found suitable for the purpose, and such a rubber composition valve disc is illustrated in Fig. 4, wherein it is indicated by 40a. 'I'he valve disc 40 obviously must be of smaller diameter than that of the bore in the lower portion of the valve body 33, so that lower portion of the valve body 33 is provided with a series of vcircumferentially spaced inwardly projecting supporting lugs 38, on which port 39 is an air pressure actuated valve disc 4|).`

which valve disc, according -to the illustration of Figs. 1 and 2, is made of thin sheet metal such,

when it is seated upon the supporting screen 33, air will be permitted to pass therebetween and the walls of the bore 36 at points intermediate the supporting lugs 38; but it is equally important 4that the valve disc 40 be of greater diameter than that lof the bore in the upper portion of the valve body 33, so that when it is A in its elevated position against the valve surface 31, itvwill completely/cut of! and close the bore through the upper portion of the valve body.l

Under operation of the engine the intake valve I6 will, of course, be, opened duringthe downward intake strokes of the piston 1 so as lto permit air to be drawn from the atmosphere through the intake conduit 2| and interposed air cleaner 21 to the combustionchamber I4 through the intake port 25, and said valve will be closed at the termination of the intake stroke of the pistonand will remainclosed during the succeeding compression, explosion and exhaust strokes of the piston. 'I'his rapidly occurring series of air intake cycles will produce a low pressure or rela- -tively high vacuum condition in the intake conduit as a result of the restriction to air iiow afforded by the conduit 26 and interposed air cleaner. In other words', under operating conditions of the engine themean average pressure condition in the intake conduit, as measured,

for example, by the conventional U tube manometer, will be a sub-atmospheric pressure or socalled partial vacuum. However, as previously indicated, the pressure in the intake conduit is not constant even under constant throttle and constant load but does, in fact, reach its lowest.

pressure or greatest condition of depression during the intake stroke of the piston, at which time the valve I5 is open; and then, upon closing of the intake valve I5, the abrupt stopping of the rapidly moving column of air through the intake OPERATION-Figs. 1 to 4 inclusive Under the above described conditions existing in the air intake conduit 26, under operation of the engine, the valve dise 40 will be `elevated to its upper valve closed position, shown by dotted lines in Fig. 2, during all times that the pres-r sure within the intake conduit 26 at the point of connection of the conduit 30 thereto is below that existing in the crank-case I6, during pressure-surge' intervals caused by rapid closing of the valve I5 and resulting in pressure surges in the intake conduit 26 which exceed the pressure existing in the crank-case I0. Hence, each time the valve I5 is closed the pressure surge within the conduit 26 will momentarily be suiiicient to open the valve 32 and cause injection of air from the intake conduit 26 through the valve 32 and conduit 30 to the crank-case, and this intere CaSe 1S can quite readily aasogaoo s load conditionsr but when the throttle valve Il is closed down to slow speed, l6w`load or idling mitrenuy 'injected dean nochv air wm se returned to thev intake conduit 2lthrough the.

crank-case outlet conduit 3i. By means of the conduit Il, which is open to flow of air in either direction, the crankin the intake conduit 2l, and this materially aids in the circulation of air throughy the crank-case.- It' has been round desirable to maintains, pressure condition in the crankcase slightly above that oi' atmosphere, so that the tendency will be to blow air out through any dition existing subject to the-mean laverage pressure con..

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such small leaks as may occur in even a well l sealed -c ank-case rather than draw air in such possible leak: and this condition be brought about with the Sys'- tem described by merely so proportioning the air-handling ability of the crank-case inlet' and crank-case outlet Il as to obtain the desired pressurel balance. In arriving at a proper balance to obtain this slight positive pressure condition in the crank-case, piston blow-by must, of course, be taken into consideration. Usually. the cross-sectional area of the conduit Il will be much less than that of the conduit 3l.

Fins I'andz' -In lli'ig. 1' the conventional parts oi' the engine illustrated are substantially like those indicated in Fig.- 1 and are indicated by like characters plus the prime mark. In Fig. 1, however, the engine may, as previously indicated, be assumed to be oi' gasoline burning type since a carthrough' burei'or II, having a conventional butterfly throt-l tle valve is illustrated as being interposed in the intake conduit 2t'.

v I'he Ventilating system similar to'. that of Eiga. 1 to 4 inclusive. and includes a crank-case air inlet conduit ll' from the engines intake to the crank-case having interposed therein a one way check valve I2' that is similar to that otFigs. 1 to 4, and a crankcaseV air outlet conduit 2l' that connects. the crank-casato the engines intake conduit 2C'- in a mannersimilar to that of conduit 2l of Fiss.

1 to 4., Insofar vas the operation of this i'orm of of Figs. l' and'2' isV j maintained largely by high vacuum or low sub-atmospheric pressure e then present in positions, ventilation of the crank case will be virtue oi.' the extremely the intake conduit at the point ot connection of the conduit 29'. Otherwise stated, the velocity through the intake conduit 2i' will decrease as the throttle valve IB is moved from open toward closed position and will be so low when the valve It reaches its idling position sh wn in the drawings that the tendency for air to move into the crank case through the con-- duit 3l' as a result of air ram eiiects in the conduit 2l' will be very low. Howeve in about the same degree as the positive pressure air ram eilects decrease u nder closing of the throttle valve, the degree of vacuum within the conduit '26T at the engine sideof the throttle valve will be built upand will become increasingly more effective so that the velocity of air movement 'through the crank case will be maintained quite pressure pulsations or air ram eiIects within the conduit 26' at the point of connection oiconduit II'.. Ot course. when the throttle valve is vopen the restriction produced thereby willv be so low that thesystcm will function almost identicaliy to that of Figs. l to 4'.

What I claim is:

l. The 'combination with an internal combustion engine having a crank-case, a combustion chamber. an air intake duct leading to the combustion chamber. and an engine operated intake valve for intermittently openingand closing ofi Ventilating system is concerned, the check valve 32' could be exactly the same as the check valve 82 of Figs. 1 to ibut a slight somewhat difierent form is illustrated for the purpose of example, and is, in fact, equally adapted to either of the forms herein illustrated. The valve Il' is provided with a pair of ilap valve elements Il' that co-operate with opposite valve seats 31'. These valve iiap elements are iormed'oi resilient sheet material and are rigidly anchored,

each at one point -by anchoring screws or the like 41. Under conditions oi vacuum or subatmospheric pressure within the intake conduit 2B', the iiap valve,e1ements Il' seat tightly against their respective seats 31' and prevent movements of air ina direction from the crank-- case to the intake conduit,but under pressure surge conditions within' the intake conduit when the pressure therein becomes above that within the crank case. the nap-valve elements Il' readcommunication between the air intake duct and combustion chamben'oi' a crank-case Ventilating system comprising an air outlet from the crankcase, a conduit extendingirom the combustionchamber air intake to thecrank-case and having interposed therein a one-way check valve permitting airto ilow only in the direction from the combustion-chamber airgintake duct to the crank-case, whereby to utilizethe instantaneous pressure surges produced in theintake under intermittent closing of the intake valve to force air from the engine intake duct into and through the crank-case.

. 2. The structure deilned in claim 1 in which the said crank-case air outlet is connected to the e combustion-chamber air intake, whereby it will ily v yield and permitirse e o! aix' from theV intakel `conduit to the crank-case.

,E In this preferred adaptation of the invention to engines having throttle valve' equipped carburetors in the intakes, the operation oi a ventilating system is'substantially the same as described in connection with Figs. 1 ,to 4, inclusive when the throttle valve is open and the engine operation under comparatively high speed or besubiect to the predominant low pressure condition of the intake.

3. The combination with an internal combustion engine of the reciprocating piston type. and having a crank-case, a combustion chamber, an air intake duct leading to the combustion chamber, and an engine operated intake valve for alternately opening and closing communication between thesaid air intake duct and combustion chamber, ot a' crank-case Ventilating system comprising an air outlet leading from the crank-case. and a check-valve-equipped crankcase air intake conduit extending from the combustion-chamber air intake duct, at a point on the atmosphere side ofthe intake valve, to the crank-case, said check valve permitting free owof air from the engine air intake duct to the crank-case under pressure surges produced in the engine air intake duct under intermittent closing of the intake valve but preventing reverse vflow of air from the crank-case under partial vacuum conditions existing in the intake conduit when the intake valve is open.-

4. The combination with an internal combustion engine of the reciprocating piston type and which is providedwith a crank-case, a combustion chamber, an air intake duct leading from atmosphere to the combustion chamber, and an engine operated intake valve for alternately opening and closing communication between'the said air intake duct and the combustion chamber, of a crank-case Ventilating system comprising at least two conduits between the said combustion-chamber air intakeduct and the crankcase, one of said crank-case Ventilating system ducts having'incorporated therein a check valve permitting flow of air the crank-case.

5. The structure definedin claim 4 in which the check-valve-equipped conduit is proportioned to ail'ord less restriction to the flow of air than is the other of said connections between the lcrank-case and combustion-chamber air'intake crankcase,.and a conduit connecting the combustion-chamber air intake duct to the crankcase and incorporating means for preventing iiow of air through said Ventilating system conduitin the direction of the combustion-chamber intake conduit but permitting free iiow o! air through said Ventilating system conduit from said combustion-chamber intake conduit toward the crank-case when the pressure in the combustion-chamber intake conduit exceeds that in the crank-case.

8. 'I'he combination with an internal combustion engine having a crank-case, a combustion chamber, an air intake duct leading to the combustion chamber and having interposed therein a restriction producing means, and an engine operated intake valve for intermittently .opening and closing communication between the air intake duct and combustion chamber, of` a crankcase Ventilating system comprising an air outlet duct leading from the crank-case to the intake duct at oneside of the said restriction producing means, and a crank-case air intake duct extending from the combustion chamber air intake at a point on the other side of saidfrestriction producing means to the crank-case and having interposed therein a one-way check valve permitting air to flow only in the direction of the crank-case.

only in the direction ol!y 9. The combination with tion engine of reciprocating piston type, said engine having a sealed crank-case, a combustion chamber, an air intake duct leading to the combustion chamber and having a throttle valve interposed therein, and an engine operated intake valve'for alternately opening and closing oil? communication between said air intake duct and combustion chamber, of a crank-case ventilating system comprising anair outlet leading from the crank-casete the intake duct'at a point on the engine side of said throttle valvel and a check valve-equipped crank-case air intake duct extending from the combustion-chamber air intake duct, at a point on the atmosphere side of the throttle valve, said check valve permitting free flow of air from the engine air intake duct to the crank-case under pressure surges produced in the engine air intake duct under intermittent closing of the intake valve but preventing reverse iiow of air from thecrank-case under partial vacuum conditions existing in the intake duct when the throttle valve is open.

10. The combination with an internal combustion engine having a sealed crank case, and an intake provided with a throttle valve therein, of a crank case Ventilating system comprising conduits extending from the intake at opposite sides of the throttle valve and independently opening into the crank-case at points above the oil level in the crank-case, and a one-way valve interposed in one of said crank-case ventilating system conduits for permitting free flow of air from theintake conduit to the crankcase, but preventing reverse iiowv of air theretion engine having a' through. f

11A. The combination with an internal combussealed crank-case, and an intake provided with crank-case Ventilating system comprising conduits extending from of the carburetor and independently opening into the crank-case at points above the oil level in the crank-case, and a one-wayopening check- Y valve interposed in one of 'said crank-case ventilating system conduits that connects to the engine intake-at the atmosphere side of the carburetor.-

12. The combination with an internal combustion engine having a sealed crank-case, and an intake provided with a throttle valve-equipped crank-case Ventilating system at opposite sides of the carburetor throttle valve and independently opening into the 4crank-case at points labove theoil level in the crank-case, and a one-way opening check l in the Ventilating system conduit that connects to the engine intake at the atmosphere side oi" the carburetor throttle valve.

13. The combination with an internal cmbusl i tion engine having a sealed crank-caseuand an intakeA provided with a throttle valve-eduipped carburetor, of a crank-case Ventilating system comprising conduits extending from 'the intake"` throttle lvalve-'equipped at opposite sides of the carburetor and independently opening intoithe crank-case at points abovethe oil level inthe' f crank-case, and a one-way opening check-valve interposed in one of said Ventilating system conduits.

' WILFRED W. LOWTHER.

an internal combusopening check a carburetor therein, of a 1 the intake at opposite sidesv valve interposed

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