US3722364A

US3722364A - Reciprocating fluid motor

Info

Publication number: US3722364A
Application number: US00132373A
Authority: US
Inventors: P Durand
Original assignee: DBA SA
Current assignee: DBA SA
Priority date: 1970-04-15
Filing date: 1971-04-08
Publication date: 1973-03-27
Anticipated expiration: 1990-03-27
Also published as: DE2118480A1; CA923387A; SE368734B; GB1303772A; FR2090025A1; SU365077A3; FR2090025B1; ES390245A1; BR7102188D0; RO60847A

Abstract

A reciprocating fluid motor, notably for operating a pump comprising an enclosure divided into two pressure chambers by a movable wall, said movable wall experiencing a forward stroke and a return stroke and being resiliently urged towards the return position, a control device responsive to the position of the movable wall controlling a distributing valve to alternately communicate one of said pressure chambers with a high pressure equalling the pressure residing at all times in the other chamber, and with a lower pressure. In this motor the control device and the distributing valve are mounted within the thickness of the movable wall, and the control device is a fluidic flip-flop. If air is selected as energizing fluid for the motor, the high and low pressures can be the atmospheric pressure and the vacuum created in the intake manifold of an engine respectively.

Description

United States Patent 1 91 Durand I 51 Mar. 27, 1973 RECIPROCATING FLUID MOTOR Pri Examirier-Alan Cohan 75 Inventor. Phil! Durand St. Denis, France 1 I 1 Assistant Examiner-4mm C. Cohen Asslgneel Sofie! yme D.B.A. Attorney-W. N. Antonis and Plante, Hartz, Smith & 22 Filed: Apr. 8, 1971 10mm [21] Appl. No.: 132,373 57 ABSTRACT I A reciprocating fluid motor, notably for operating a [30] Foreig" Application Pnomy Dam pump comprising an enclosure divided into two pres- Apr. 15, 1970 France ..70l3576 sure chambers by mOVable wan, Said movable wan experiencing a forward stroke and a return stroke and 52 US. Cl. ..91/3, 91/304, 91/422, being resiliently urged towards the return position, a

' 137/315 417/402 control device responsive to the position of the mova- 51 Int. Cl. ..Fl5b 13/042, FlSc 1/10 ble wall controlling a dismbutins valve to alternately 58 Field of Search ..91/3, 304, 422; lav/81.5; communicate one of said Pressure chambers with a 417 402 high pressure equalling the pressure residing at all 1 times in the other chamber, and with a lower pressure [56] References Cited In this motor the control device and the distributing valve are mounted within the thickness of the movable UNITED STATES PATENTS wall, and the control device is a fluidic flip-flop. [f air 3,208,448. 9/1965 Woodward ..91/3 x is Selected as energizing fluid for motor the high 3,282,282 11/1966 SOWe1'5 and low pressures can be the atmospheric pressure 3,393,692 7/1968 Gearyw. and the vacuum created in the intake manifold of an 3,408,899 ll/l968 Golden.... engine respectively. 3,516,763 6/1970 Manton.. 3,599,535 8/1971 Rohm ..9l/42O 4 ChiIlE, 2 Figures RECIPROCATING FLUID MOTOR This invention relates to a reciprocating fluid motor, notably for operating a pump unit designed for use in a motor vehicle. I

More particularly, the invention is directed to a fluid motor of the type wherein a reciprocably movable wall dividing an enclosure into two fluid pressure chambers is connected to a utilization device which may be a piston-cylinder arrangement, thus forming a pump unit capable of drawing a fluid and expelling this fluid under pressurized condition. The reciprocating motion is produced by a fluid pressure differential acting on the movable wall, periods of pressure difference being separated by periods of pressure balance during which the movable wall is resiliently urged toward a return position. The energizing fluid may be a gas or a liquid. For example, if air is selected as energizing fluid, one of the pressure chambers may be communicated at all times with atmosphere, and the motion of the movable wall can be obtained by alternatively communicating the other pressure chamber with atmosphere and with a low pressure source such as the vacuum prevailing in the intake manifold of a vehicle engine.

It is known to utilize a distributing valve, for example a slide valve, for producing the sequence of pressure changes in the chamber in which the pressure is to be periodically modified. The position of the distributing valve is controlled in response to the position of the movable wall by means of a mechanical control device comprising movable components which are substantially bulky, not only requiring space but also limiting the operating speed of the motor due to inertia. Moreover, these movable components are subjected to wear, thus limiting the operating life of the motor.

An object of the invention is to provide a fluid motor wherein a distributing valve is controlled by a control device which comprises no movable components, thus providing a motor of small size and increased ruggedness.

According to the invention, the distributing valve and the control device are mounted within the thickness of the movable wall of the fluid motor, said control device being a fluidic flipflop.

The invention will now be described by way of example with reference to the accompanying drawings in which a FIG. 1 is a sectional view of a pump unit operated by a fluid motor according to the invention.

FIG. 2 is a sectional view of a pump unit with another embodiment of the fluid motor.

As shown in FIG. 1, a pump unit is operated by a fluid motor which has a casing consisting of a forward shell 1 and a rear shell 2 joined by respective flanges thereof, with, the outer edge of an annular diaphragm 6 clamped between the flanges to seal their juncture. The inner edge of the diaphragm 6 is connected to a circular plate 5 dividing the motor casing into a forward and a rear chambers 3, 4. The diaphragm 6 is sufficiently supple for allowing plate 5 to be axially movable within the casing.

A cylinder 8, centrally affixed on the outer surface of the forward shell 1 of the motor casing, is cooperating with a piston 7 connected to the movable plate 7. A delivery valve 11, an inlet valve 12 and an exhaust valve 13 are provided in the head of the cylinder 8.

The movable plate 5 is adapted to receive an alternating motion, and to transmit its movement to the piston 7.

Movement of plate 5 in the forward direction, namely toward the forward shell 1, is produced by a pressure differential as will be explained later. Return movement of the plate 5 occurs when pressure balance is restored, and is produced by the force of a helical spring 10 biased between shell 1 and plate 5.

In the example shown in FIG. 1, the rear pressure chamber 4 is communicated at all times to atmosphere through a port '14. Movement of plate 5 is then obtained by creating a low pressure condition in the for ward chamber 3.

According to the invention, the forward pressure chamber 3 is alternately communicated to a low pressure source and to atmosphere by means of an assembly comprising a slide valve 15 and a fluidic bista ble trigger device 16.

The bistable trigger device 16 is a conventional fluidic flip-flop which comprises an input channel 17, a pair of control ports 18, 19 and a pair of

output channels

20, 21. A pair of

interconnected vents

22, 23 are grafted on the output channels respectively.

The flip-flop output channel 20 is in communication with the slide valve 15. The output channel 21 is connected to the forward chamber 3 through an opening 25 of the movable plate 5. The

vents

22, 23 are connected to a port 27 through an intake conduit 26 which extends along the slide valve 15. The port 27 is con nected to a low pressure source not shown, for example to the intake manifold of a vehicle motor, through a flexible tube 28 which does not impede the movements of the plate 5.

The slide valve 15 is connected to the intake conduit 26 through a pair of spaced

openings

29, 30, and to the atmospheric pressure of rear chamber 4 through another opening 32. The slide valve comprises a valve member 31 having two

lands

31A, 31B.

Lands

31A, 31B and the

openings

30,32 are so arranged that opening 30 is closed by land 31A when the valve member 31 is in the upper position (as shown in theldrawings) while opening 32 is closed by land 318 when the valve member is in the lower position. The space between

lands

31A, 31B defines a distribution chamber which is connected to the low pressure of forward chamber- 3 through a passage 33 extending through the, movable wall 5. Valve member 31 is urged upwards by a spring 34, and its downward stroke is limited by a stop member 35.

When the pump unit is not operating, or at the end of the rearward stroke of the movable plate 5, (position in which the pump unit is represented in FIG. I), the flipflop control port 18, directed towards the rear of the housing, is closed by a valve seat 36 affixed on a boss 37 carried by the rear shell 2. At the end of the forward stroke, the other flip-flop control port 19, directed towards the forward shell 3, is closed by a valve seat 38. The valve seat 38 is mounted within an opening of the movable plate 5 and at the end. of the stroke, it is pressed against the control port 19 by a boss 39 carried by the forward shell 3.

Assuming that the pump is not operating, as illustrated in FIG. 1, movable plate 5 is urged towards the rear by spring 10, so that control port 18 is closed by valve seat 36. Spring 34 in the slide valve urges valve member 31 upwards, thus clearing the opening 32 to communicate the forward chamber 3 with the rear chamber 4, hence to atmosphere since the rear chamber is connected at all times to atmosphere through port 14.

When the low pressure source starts operating, for example upon starting the motor having its intake manifold connected to the flexible tube 28, a vacuum is created in conduit 26 and air is drawn from the lower portion of the slide valve 15 through the opening 29. Air is also drawn through flip-

flop vents

22, 23, thus creating a vacuum in the

output channel

20, 21 of the flip-flop.

The vacuum thus created through

vents

22, 23 gives rise through input channel 17 to a high speed jet, and the entrainment flow of this jet produces a low pressure condition in the control port 18. Since the opposite control port 19 is communicated to atmosphere through a passage 40, the jet is repelled towards the wall of the outlet channel 20, and the jet will remain attached to this wall as long as the control conditions are not modified, in other words as long as a low pressure condition does not evolve in the control port 19, even if atmospheric pressure is restored in control port 18.

Through channel 20, the jet impinges on the valve member 31 in the slide valve. The valve member is then urged downwards until engagement with the stop member 35, since the lower region of the slide valve is evacuated. As the slide valve 31 is moved, the opening 32 is closed while the opening 30 is opened. Vacuum is then established in the forward chamber 3 through intake conduit 26, via opening 30 and passage 33. Vacuum is also established through a by-pass comprising the opening 25 which is connected to the flip-flop output channel and the vent 23. The vacuum in the forward chamber 3 causes the plate 5 to move in the direction of the forward shell 1, forward stroke of the plate 5. Fluid, or example oil, contained in cylinder 8 is compressed by piston 7, then expelled through inlet valve 12.

At the end of the forward. stroke, the control port 19 is closed by the boss 39 pushing the valve seat 38, while the other control port 18 is connected to atmosphere. This reversal of the conditions in the control ports results in a modification in the balance of the jet, The jet is then separated from the wall of the outlet channel 21, becoming attached to the wall thereof. Thus, the outlet channel 20 is connected to the vacuum, and, in response to the pressure balance, the valve member 34 is urged upwards by the spring 34.

In the upper position of valve member 31, the opening 30 is closed and the opening 32 is cleared anew. Air enters the forward chamber 3 through the passage 33, as well as through the opening 25 communicating with the flip-flop, and, when a pressure balance is obtained, the spring 10 returns the movable plate 5 rearwards. A volume of oil corresponding to the stroke of the piston 7 is then drawn from the delivery valve 11 into the cylinder 8.

The operating cycle depicted above is repeated as long as a vacuum is maintained in the flexible tube 28.

In the embodiment shown in FIG. 1, the mixed arrangement of a jet acting on one end of the valve member and of a spring acting on the other end has been used for controlling the slide valve.

FIG. 2 shows an embodiment in which a jet is alternately directed on either end of the valve member. Like numerals are used for designating like parts in FIGS. 1 and 2. In FIG. 2, it can be seen that the lower portion of the slide valve 15 comprises no stop member, no spring, no opening communicating with the intake conduit 26. Moreover, the flip-flop output channel 21 is not connected to the forward chamber 3. By contrast, the flip-flop output channel 21 is connected to the lower portion of the slide valve 15 through a conduit 41. Vacuum and atmospheric pressure are alternately established in the forward chamber 3 through

openings

30, 32 and through passage 33.

What we claim is 2 1. In a fluid motor:

a housing defining a chamber therewithin;

a piston slidably mounted in said chamber and movable between forward and return positions;

resilient means yieldably urging said piston toward the return position;

valve means carried in said piston and shiftable from a first condition communicating substantially equal fluid pressure levels across said piston to a second position communicating a pressure differential across said piston to thereby urge the latter toward the forward position; and

fluidic control means carried in said piston for shifting said valve means, said fluidic control means producing a control jet shiftable from a first condition urging said valve means toward said second position to a second condition permitting said valve means to return to the first position, and means responsive to the position of said piston to shift the control jet to the first condition when the piston is disposed in the return position and shifting said control jet to said second condition when the piston is disposed in said forward position.

2. The invention of claim 1:

said means responsive to the position of said piston including first and second control ports, a first valve seat carried by said housing for closing said first control port when the piston is in the return position to permit fluid pressure at the second control port to urge the control jet to the first condition, and a second valve seat carried by said housing for closing said second control port when the piston is in the forward position to permit fluid pressure at the first control port to urge the control jet to the second condition.

3. The invention of claim 2:

said valve means including a valve spool movable between said first and second positions;

said control jet in said first condition acting on one end of the valve spool to urge the latter to the second position; and

spring means acting on the other end of said valve spool to urge the latter toward said first position.

4. The invention of claim 3:

said piston dividing said chamber into a pair of compartments, one of said compartments being communicated to atmosphere, said spool valve in said first position communicating the other compartment to atmosphere and in said second position communicating the other compartment to a vacuum source.

Claims

1. In a fluid motor: a housing defining a chamber therewithin; a piston slidably mounted in said chamber and movable between forward and return positions; resilient means yieldably urging said piston toward the return position; valve means carried in said piston and shiftable from a first condition communicating substantially equal fluid pressure levels across said piston to a second position communicating a pressure differential across said piston to thereby urge the latter toward the forward position; and fluidic control means carried in said piston for shifting said valve means, said fluidic control means producing a control jet shiftable from a first condition urging said valve means toward said second position to a second condition permitting said valve means to return to the first position, and means responsive to the position of said piston to shift the control jet to the first condition when the piston is disposed in the return position and shifting said control jet to said second condition when the piston is disposed in said forward position.

2. The invention of claim 1: said means responsive to the position of said piston including first and second control ports, a first valve seat carried by said housing for closing said first control port when the piston is in the return position to permit fluid pressure at the second control port to urge the control jet to the first condition, and a second valve seat carried by said housing for closing said second control port when the piston is in the forward position to permit fluid pressure at the first control port to urge the control jet to the second condition.

3. The invention of claim 2: said valve means including a valve spool movable between said first and second positions; said control jet in said first condition acting on one end of the valve spool to urge the latter to the second position; and spring means acting on the other end of said valve spool to urge the latter toward said first position.

4. The invention of claim 3: said piston dividing said chamber into a pair of compartments, one of said compartments being communicated to atmosphere, said spool valve in said first position communicating the other compartment to atmosphere and in said second position communicating the other compartment to a vacuum source.