US3223392A - Return flow carburetor - Google Patents

Description

Dec. 14, 1965 T. M. BALL 3,223,392

RETURN FLOW CARBURE'I'OR Original Filed July 28, 1959 INVEN TOR. 77%477746' Mid/Z BY n q/AZW United States Patent 3,223,392 RETURN FLGW (ZAREURETGR Thomas M. Ball, Bloomfield Hills, Mich, assignor to Chrysler Corporation, Highland Park, Mich, a corporation of Delaware ()riginal application July 28, 1959, Ser. No. 830,007, new Patent No. 3,161,700, dated Dec. 15, 1964. Divided and this application dune 15, 1964, Ser. No. 381,279

4 Q'Jlaims. (Cl. 261l27) This invention relates to improvements in a carburetor particularly adapted for use with an automobile internal combustion engine. This application is a division of copending application, Serial Number 830,007, filed July 28, 1959, now Patent Number 3,161,700, issued December 15, 1964.

In conventional carburetors, a fioat controlled fuel inlet needle valve is employed to regulate the fuel level in the carburetor fuel bowl. Small dirt particles sometimes interfere with effective operation of the valve, as for example by becoming lodged between mating valve seats which otherwise cooperate to regulate the fuel flow into the fuel bowl. Also the floats require considerable size in order to be effective because of the comparatively low specific gravity of the fuel. In consequence the size of the fuel bowl must be appreciably larger than is otherwise desired.

An important object of the present invention is to provide an improved carburetor which avoids the fore going objections and in particular to provide a floatless carburetor which does not require a fuel inlet needle valve.

Another object is to provide such a construction including an overflow standpipe in the fuel bowl having an upper opening which determines the maximum fuel level in the bowl. A fuel inlet pump is provided to pump fuel into the bowl at a rate in excess of demand. The excess fuel overflows into the standpi-pe and is returned to the fuel tank. In order to overcome adverse grade conditions which prevent the excess fuel from returning to the tank by gravity flow, a scavenging pump is provided in the fuel return line between the overflow standpipe and the tank.

Among other advantages of the above structure, elimination of the necessarily large float enables utilization of a comparatively small fuel bowl closely adjacent the inlet air induction conduits of a multiple barrel carburetor, for example. The small fuel bowl thus located is less sensitive to grade and inertial effects and enables uniform fuel distribution to each of the several induction conduits. Also recirculation of the fuel drives off its more volatile fuel fractions and thereby minimizes some of the problems of the conventional float controlled carburetor, as for example those concerned with vapor formation.

In order to provide adequate fuel during maximum engine speed at wide open throttle, a fuel inlet pump is provided which delivers an excess supply of fuel to the fuel bowl during all operating conditions of the engine. When the throttle is suddenly closed while the engine is still operating at high speed, unless some provision is made to the contrary, a major portion of the fuel supplied to the fuel bowl will be recirculated. In general the life of a fuel pump and in particular the life of an engine driven diaphragm type pump, which is preferred for supplying fuel in the quantity required and at a substantially uniform pressure regardless of changes in engine speed, depends upon the quantity of fuel pumped.

For the above reasons, as well as the desirability of conserving power in an automobile engine and of minimizing fuel heating by excessive recirculation, another object of the present invention is to provide improved simple and highly effective means for supplying fuel to the fuel bowl in reasonable and safe amounts related to engine requirements.

Another object is to provide a carburetor and diaphragm fuel pump combination of the type described wherein the pump comprises a pumping chamber having a movable diaphragm defining one wall thereof. The pumping chamber is provided with check valve controlled inlet and discharge ports in communication with a fuel tank and with the fuel bowl respectively and operative so that during movement of the diaphragm in one direction in an intake stroke to enlarge the volume of the pumping chamber, fuel is drawn from the tank into the pumping chamber. During movement of the diaphragm in the opposite direction in a pumping stroke, fuel is discharged from the pumping chamber into the fuel bowl. The diaphragm is secured to a plunger arm for actuation thereby. A pumping spring under compression between the diaphragm and a fixed portion of the pump mechanism yieldingly urges the diaphragm in said opposite direction to cause the pumping stroke. A pivotal arm engageable with a rotating cam driven by the automobile engine to be pivotally oscillated thereby is also engageable with the plunger to move the latter in said one direction against the force of the pumping spring to compress the latter. The pivotal arm is also freely engageable with the plunger so that during the reverse pivotal movement of the arm, the latter will move independently of the plunger and release the diaphragm for spring urged pumping movement in said opposite direction, but will not positively urge movement of the diaphragm in said opposite direction. In consequence, the pumping force will result entirely from the compressed pumping spring and will be substantially constant regardless of the speed of the engine or of the pivotally oscillated arm.

Other and more specific objects are to provide such a diaphragm pump and carburetor combination having means for varying the pumping stroke of the diaphragm in said opposite direction by a direct linkage with the throttle actuating mechanism, or by pressure actuated means connected with the engine air inlet induction system or with the discharge side of the scavenging pump.

Other objects of this invention will appear in the following description and appended claims, reference being bad to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

FIGURE 1 is a schematic mid-sectional view of a floatless return flow carburetor and pump embodying the present invention showing general means actuated by the throttle valve for controlling the diaphragm pumping stroke.

FIGURE 2 is a view similar to FIGURE 1 but showing a specific mechanical linkage with the throtle mechanism for controlling the diaphragm stroke.

FIGURE 3 is a view similar to FIGURE 2 illustrating a modification.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring to FIGURE 1, the carburetor shown comprises a cast housing formed to provide an air inlet induction conduit including a venturi portion 10 having a restricted venturi 11 at its upper portion and a throttle blade 12 pivotally mounted on a shaft 13 at a lower portion usually referred to as the throttle body. An upper portion of the casting is formed to provide an air horn 14 adapted to be connected with the usual air filter and opening at its downstream end into the venturi 11 to supply air J thereto. The casting portions and 14 are suitably secured together, as for example by screws not shown, and comprise an upper portion of the air inlet and fuel mixing induction system which extends downstream of the throttle valve 12 and discharges into the dual engine cylinders in a conventional manner.

Integral with the casting 10 in the present instance is a fuel bowl casting 15 containing an annular chamber or fuel bowl 16 enclosing a cylindrical standpipe or weir 17 which also serves as an acceleration pump cylinder containing a plunger 18 reciprocable in its lower portion and secured to a plunger shaft 19 for actuation thereby. Where desired the shaft 19 is connected by suitable linkage with a pedal operated accelerator mechanism which controls the opening and closing of valve 12 to operate conjointly therewith. Upon upward movement of plunger 18, fuel is drawn into the lower portion of chamber 17 via conduit 20 in communication with the bowl 16. A suitable check valve illustrated schematically as a ball check element 21 normally seats at the mouth of the duct 20 opening into the lower portion of chamber 17 to prevent loss of fuel therefrom but is raised from its seat by the fuel flow into chamber 17 on the upstroke of plunger 18. Upon downward movement of plunger 18 the fuel is forced from chamber 17 into the induction conduit via acceleration fuel conduit 22, ball check valve 23, and nozzle 24 which latter discharges into the induction conduit at a location immediately above the throat of venturi 11. The check valve 23 is schematically illustrated as a ball normally urged by a spring to a seated position closing nozzle 24 from the interior of chamber 17, the ball being readily movable upward against the tension of its seating spring by the acceleration fuel presssure upon downward movement of plunger 18. The main fuel to the engine is supplied via duct 25 which opens at its lower end through metering port 26 into the fuel bowl 16 and communicates at its upper end with a fuel nozzle 27 having its discharge orifice located within the throat of venturi 11.

In accordance with the structure described thus far, fuel entering the bowl 16 in excess of engine requirements overflows the upper edge of standpipe 17 which thereby maintains the fuel in the bowl 16 at a predetermined maximum level determined by the effective height of the standpipe 17 without recourse to a float operated mechanism. Fuel is supplied to the bowl 16 from a suitable fuel tank via conduit 28.

A multiple piece fuel pump housing 37 comprising an upper dome 38 and a lower basin 39 cooperate with diaphragms 40 and 41 respectively to provide an inlet fuel pumping or working chamber 42 and an exhaust fuel pumping or scavenging chamber 43. Springs 44 and 45 under compression between portions of housing 37 and diaphragms 40 and 41 respectively urge the former diaphragm upwardly and the latter diaphragm downwardly to effect the pumping strokes for the respective chambers 42 and 43.

The upper working chamber 42 comprises a portion of supply duct 28 which communicates upstream of chamber 42 with the fuel tank. Fuel enters and leaves chamber 42 via an inlet port 46 and a discharge port 47 associated with check valves 48 and 49 respectively. Upon downward movement of diaphragm 40 as explained below, fuel is drawn in the direction of the arrow 28a from the tank and through inlet port 46 into working chamber 42. During this operation ball valve 48 is forced from its seat at port 46 by the fuel flow, and ball valve 49 seats at the discharge port 47 to close the latter from the fuel bowl 16. Upon upward movement of diaphragm 40, ball valve 48 is caused to seat at port 46 to close the working chamber 42 from the fuel tank. During this operation, the pressure exerted in chamber 42 unseats ball valve 49 from port 47 and supplies fuel via conduit 28 to the fuel bowl 16. The spaces at the sides of the diaphragms 40 and 41 opposite chambers 42 and 43 respectively are 4 vented to the atmosphere by ducts 50 and 51 to facilitate the pump operation.

Fuel is returned in the direction of arrow 52a from standpipe 17 to the fuel tank via fuel return conduit 52 which includes chamber 43 as a portion thereof. Upstream, the conduit 52 communicates with standpipe 17 at a location above the uppermost limit of movement of plunger 18. The return fuel enters chamber 43 via port 53 and discharges from chamber 43 via port 54. Ball check valves 55 and 56 are associated with ports 53 and 54 respectively, so that upon upward movement of diaphragm 41 as described below, ball 56 seats against port 54 to close chamber 43 from the fuel tank. During this operation, ball 55 is unseated from port 53 to open communication between chamber 43 and standpipe 17 and to draw fuel from the latter. Upon downward movement of diaphragm 41, ball 55 is seated against port 53 to close chamber 43 from standpipe 17. Simultaneously ball 56 is unseated from port 54 by the pressure in chamber 43 to discharge fuel from the latter in the direction of arrow 52a to the tank. Movement limiting pins in the conduits 28 and 52 associated with the ball valves 48, 49, 55 and 56 prevent undue movement of the balls from their associated ports. Inasmuch as the check valves are well known, these are merely shown schematically and are not discussed in further detail.

Actuation of the diaphragms 40 and 41 is accomplished by driving shafts 57 and 58 connected to these diaphragms and terminating in enlarged heads 59 and 68 respectively. Pivotal levers 61 and 62 are pivoted on housing 37 at locations 63 and 64 respectively between their ends. Each lever has one end engaged with a rotating eccentric cam 65 mounted on a shaft 66 driven by the automobile engine. The opposite ends of the levers 61 and 62 are provided with oversized openings 67 and 68 through which the rods 57 and 58 extend freely to enable their relative sliding movement with respect to the levers 61 and 62 until the levers engage the enlarged heads 59 and 60.

Upon operation of the automobile engine, shaft 66 is rotated to turn cam 65 and thereby cause pivoting of levers 61 or 62. Upon clockwise pivoting of lever 61, or counterclockwise pivoting of lever 62, the head 59 or 60 is engaged to pull the associated rod 57 or 58 in the direction to compress the spring 44 or 45 as the case might be. Upon counterclockwise pivoting of lever 61 and clockwise pivoting of lever 62, the oversized openings 67 and 68 enable the levers to swing independently of the shafts 57 and 58, whereupon springs 44 and 45 are released to force diaphragms 40 and 41 in pumping actions toward the associated dome 38 and basin 39. The pivotal action of levers 61 and 62 merely compresses the springs 44 and 45 alternately, which latter then exert resilient force to effect the pumping action of the associated diaphragms 40 and 41. In consequence, fuel is discharged from chamber 42 at a uniform optimum pressure determined by the force of spring 44. Upon the upward spring urged pumping stroke of diaphragm 40, fuel is discharged via port 47 to fuel bowl 16. All fuel in excess of engine requirements overflows the standpipe 17 and returns by conduit 52 to chamber 43 via port 53, whereupon the fuel is pumped to the fuel tank by downward spring urged pumping movement of diaphragm 41.

In order to prevent too great an excess of fuel from being pumped to fuel bowl 16 when the engine is operating at comparatively light load, means are provided for limiting the maximum movement of diaphragm 40 during the spring urged pumping stroke. As illustrated in FIG- URE 1, eccentric cam 69 is keyed to a pivot shaft 70 mounted within housing 37 and extending to the exterior thereof. An operable connection between cam 69 and throttle valve 12 is indicated by the broken line 71, whereby upon closing of the throttle valve 12, cam 69 is rotated to limit the maximum upward pumping stroke of diaphragm 40, as described more specifically in regard to FIGURES 2 and 3.

Thus with decreasing engine load, the pumping stroke of diaphragm 40 is decreased, the fuel flow pumped via conduit 28 into fuel bowl 16 is decreased, and recirculation of fuel to the bowl 16 is minimized. With increasing engine load, the increased pumping stroke enabled by diaphragm 40 increases the fuel flow via conduit 28 to fuel bowl 16.

FIGURE 2 illustrates the return flow carburetor and pumping mechanism as in FIGURE 1 wherein corresponding parts are numbered the same.

A generally horizontal lever 83 is keyed at one end to a lateral external extension of cam shaft 70 which in turn is keyed to cam 69 overlying diaphragm 49 as in FIG- URE 1. Cam 69 is disposed to enable increased upward pumping movement of diaphragm 40 when lever 83 is swung clockwise about the axis of shaft 70. The left end of shaft 83 is provided with a transverse pin 84 slidably secured within the yoke 85 of a pivotal shaft 86 pivotally mounted between its ends at 87 to a fixed portion of the carburetor casting 15. The left end of shaft 86 is pivotally connected at 88 to the upper end of a connecting link 89. The lower end of link 89 is pivotally connected at 90 to the outer swinging end of a crank arm 91 which in turn is keyed to an extension of valve shaft 13 exteriorly of the induction conduit 10.

Upon pivoting of crank arm 91, as for example by linkage 92 which is suitably connected with crank arm 91 and the customary pedal operated throttle mechanism, valve 12 is opened or closed. When crank arm 91 is pivoted clockwise, throttle valve 12 is progressively opened and link 39 is moved downward to swing lever 86 counterclockwise, thereby to pivot lever 83 clockwise about the axis of shaft 70 and raise the point of movement limiting engagement between diaphragm 4t and cam 69. In consequence, upon opening of throttle valve 12 during increased engine load, the pumping stroke of diaphragm 4i and the fuel flow to fuel bowl 16 are increased.

Upon counterclockwise or closing movement of valve 12 with decreasing engine load, lever 89 is moved upwardly, lever 86 is pivoted clockwise about the axis of pivot 87, and link 83 and cam 69 are pivoted counterclockwise to the position shown in FIGURE 2 to minimize the pumping stroke of diaphragm 4t and the fuel supply to bowl 16.

FIGURE 3 is concerned with a carburetor, pumping mechanism, and throttle actuated linkage including crank arm 91, links 86 and 89, and yoke 85, as in FIGURE 2, but wherein lever 83 and cam 69 are eliminated. A pin 93 slidable within yoke 85 in the manner of pin 84 of FIGURE 2 is secured to one end of a dog leg link 94 pivoted at 95 to a fixed bracket portion 37a of housing 37. The other end of dog leg link 94 comprises a vertical yoke 96 having a pin 97 slidably retained therein. Pin 97 extends transversely through a generally horizontal extending shaft 98 having a tapered wedge cam 79 at its right end arranged to be inserted between lever 61 and cam 65. Shaft 98 is also slidably supported within bracket portion of housing 37a for horizontal movement.

Upon clockwise pivoting of crank arm 91 to open throttle valve 12, lever 86 is pivoted counterclockwise as aforesaid, causing dog leg link 94- to pivot clockwise and move wedge 79 between lever 61 and cam 65 to take up the lost motion between lever 61 and enlargement 59 and thereby to increase the effective pumping stroke of diaphragm 48. In this regard, the spring which urges upward pumping movement of diaphragm 40 will be determined so as to be in an unstressed condition when lever arm 61 is in the horizontal position illustrated. Thus diaphragm 41) will be at the upper limit of its pumping movement when wedge 79 is at the withdrawn position illustrated in FIGURE 3. As wedge 79 is moved rightward in FIGURE 3 upon opening of throttle 12 with increasing engine load, the effective pumping stroke of diaphragm 4t and the fuel supplied to bowl 16 is increased.

Conversely as Wedge 79 is withdrawn leftward upon closure of throttle 12 with decreasing load, the effective pumping stroke of diaphragm 4i and the fuel flow to bowl 16 is decreased.

Having thus described my invention, I claim:

1. In a carburetor for an internal combustion engine having an intake manifold system, a throttle valve in said system, a fuel bowl, a movable-wall type fuel pumping means, inlet conduit means connecting said pumping means and bowl for supplying the latter with fuel upon operation of said pumping means, means for maintaining the fuel in said bowl at a predetermined level comprising an overflow weir in said bowl defining at least in part a chamber adapted to receive excess fuel overflowing said weir from said bowl when the fuel in said bowl attains said predetermined level, fuel return means in communication with said chamber to drain fuel therefrom upon overflow of excess fuel from said bowl into said chamber, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, a cyclical cam, follower means engageable with said cam and wall to effect reciprocation of the latter, and means operatively connected with said throttle valve for adjustably controlling the relative positions of said follower means with respect to said cam to increase the length of said pumping stroke upon opening of said valve.

2. In a carburetor for an internal combustion engine having an intake manifold system, a throttle valve in said system, a fuel bowl, a movable-wall type fuel pumping means, inlet conduit means connecting said pumping means and bowl for supplying the latter with fuel upon operation of said pumping means, fuel duct means connecting said bowl and intake manifold system for supplying fuel to the latter, means for maintaining the fuel in said bowl at a predetermined level comprising an overflow weir in said bowl defining at least in part a chamber adapted to receive excess fuel overflowing said weir from said bowl when the fuel in said bowl attains said predetermined level, fuel return means in communication with said chamber to drain fuel therefrom upon overflow of excess fuel from said bowl into said chamber, said pumping means having a reciprocable Wall movable in alternate intake and pumping strokes, adjustable movement limiting means engageable with said wall to limit the length of the pumping stroke thereof, and means operatively connecting said throttle valve and movement limiting means to adjust the latter to increase the length of said pumping stroke in accordance with the opening of said valve.

3. In a carburetor for an internal combustion engine having an intake manifold system, a throttle valve in said system, a fuel bowl, a movable-wall type fuel pumping means, inlet conduit means connecting said pumping means and bowl for supplying the latter with fuel upon operation of said pumping means, fuel duct means connecting said bowl and intake manifold system for supplying fuel to the latter, means for maintaining the fuel in said bowl at a predetermined level comprising an overflow weir in said bowl defining at least in part a chamber adapted to receive excess fuel overflowing said weir from said bowl when the fuel in said bowl attains said predetermined level, fuel return means in communication with said chamber to drain fuel therefrom upon overflow of excess fuel from said bowl into said chamber, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, pressure exerting means for yieldingly urging said wall in a pumping stroke, reciprocable actuating means operatively connected with said wall for moving the latter in opposition to said pressure exerting means to effect an intake stroke of said wall upon movement of said actuating means in one direction and for releasing said wall for movement in said pumping stroke upon movement of said actuating means in the opposite direction, and means operatively connected with said throttle valve for adjustably controlling the movement of said actuating means in opposition to said pressure exerting means for increasing said pumping stroke in accordance with opening of said valve.

4. In a carburetor for an internal combustion engine having an intake manifold system, a throttle valve in said system, a fuel bowl, a movable-wail type fuel pumping means, inlet conduit means connecting said pumping means and bowl for supplying the latter with fuel upon operation of said pumping means, means for maintaining the fuel in said bowl at a predetermined level comprising an overflow weir in said bowl defining at least in part a chamber adapted to receive excess fuel overflowing said weir from said bowl when the fuel in said bowl attains said predetermined level, fuel return means in communication with said chamber to drain fuel therefrom upon overflow of excess fuel from said bowl into said chamber, said pumping means having a reciprocable wall movable in alternate intake and pumping strokes, pressure exerting means for yieldingly urging said wall in a pumping stroke, reciprocable actuating means operatively connected with said wall for moving the latter in opposition to said pressure exerting means to effect an intake stroke of said wall upon movement of said actuating means in one direction and for releasing said wall for movement in said pumping stroke upon movement of said actuating means in the opposite direction, said actuating means including a cyclical cam and follower means engageable with said cam to effect reciprocation of said wall, and means operatively connected with said throttle valve for adjustably controlling the relative positions of said follower means with respect to said cam to increase the length of said pumping stroke upon opening of said valve.

References Cited by the Examiner UNITED STATES PATENTS 2,136,959 11/1938 Winfield 261-36 2,409,965 10/1946 Udale 261-36 2,734,729 2/1956 Loftin 26136 2,977,099 3/1961 Ball 261-36 HARRY B. THORNTON, Primary Examiner.

Claims (2)

1. IN A CARBURETOR FOR AN INTERNAL COMBUSTION ENGINE HAVING AN INTAKE MANIFOLD SYSTEM, A THROTTLE VALVE IN SAID SYSTEM, A FUEL BOWL, A MOVABLE-WALL TYPE FUEL PUMPING MEANS, INLET CONDUIT MEANS CONNECTING SAID PUMPING MEANS AND BOWL FOR SUPPLYING THE LATTER WITH FUEL UPON OPERATION OF SAID PUMPING MEANS, MEANS FOR MAINTAINING THE FUEL IN SAID BOWL AT A PREDETERMINED LEVEL COMPRISING AN OVERFLOW WEIR IN SAID BOWL DEFINING AT LEAST IN PART A CHAMBER ADAPTED TO RECEIVE EXCESS FUEL OVERFLOWING SAID WIER FROM SAID BOWL WHEN THE FUEL IN SAID BOWL ATTAINS SAID PREDETERMINED LEVEL, FUEL RETURNS MEANS IN COMMUNIATION WITH SAID CHAMBER TO DRAIN FUEL THEREFROM UPON OVERFLOW OF EXCESS FUEL FROM SAIDBOWL INTO SAID CHAMBER SAID PUMPING MEANS HAVING A RECIPROCABLE WALL MOVABLE IN ALTERNATE INTAKE AND PUMPING STROKES, A CYCLICAL CAM, FOLLOWER MEANS ENGAGEABLE WITH SAID CAM AND WALL TO EFFECT RECIPROCATION OF THE LATTER, AND MEANS OPERATIVELY CONNECTED WITH SAID THROTTLE VALVE FOR ADJUSTABLY CONTROLLING THE RELATIVE POSITIONS OF SAID FOLLOWER MEANS WITH RESPECT TO SAID CAM TO INCREASE THE LENGTH OF SAID PUMPING STROKE UPON OPENING OF SAID VALVE.

3. IN A CARBURETOR FOR AN INTERNAL COMBUSTION ENGINE HAVING AN INTAKE MANIFOLD SYSTEM, A THROTTLE VALVE IN SAID SYSTEM, INLET CONDUIT MEANS CONNECTING SAID PUMPING MEANS, INLET CONDUIT MEANS CONNECTING SAID PUMPING MEANS AND BOWL FOR SUPPLYING THE LATTER WITH FUEL UPON OPERATION OF SAID PUMPING MEANS, FUEL DUCT MEANS CONNECTING SAID BOWL AND INTAKE MANIFOLD SYSTEM FOR SUPPLYING FUEL TO THE LATTER, MEANS FOR MAINTAINING THE FUEL IN SAID BOWL AT A PREDETERMINED LEVEL COMPRISING AN OVERFLOW WEIR IN SAID BOWL DEFINING AT LEAST IN PART A CHAMBER ADAPTED TO RECEIVE EXCESS FUEL OVERFLOWING SAID WEIR FROM SAID BOWL WHEN THE FUEL IN SAID BOWL ATTAINS SAID PREDETERMINED LEVEL, FUEL RETURN MEANS IN COMMUNICATION WITH SAID CHAMBER TO DRAIN FUEL THEREFROM UPON OVERFLOW OF EXCESS FUEL FROM SAID BOWL INTO SAID CHAMBER, SAID PUMPING MEANSHAVING A RECIPROCABLE WALL MOVABLE IN ALTERNATE INTAKE AND PUMPING STROKES, PRESSURE EXERTING MEANS FOR YIELDINGLY URGING SAID WALL IN A PUMPING STROKEK RECIPROCABLE ACTUATING MEANS OPERATIVELY CONNECTED WITH SAID WALL FOR MOVING THE LATTER IN OPPOSITION TO SAID PRESSURE EXERTING MEANS TO EFFECT AN INTAKE STROKE OF SAID WALL UPON MOVEMENT OF SAID ACTUATING MEANS IN ONE DIRECTION AND FOR RELEASING SAID WALL FOR MOVEMENT IN SAID PUMPING STROKE UPON MOVEMENT OF SAID ACTUATING MEANS IN THE OPPOSITE DIRECTION, AND MEANS OPERATIVELY CONNECTED WITH SAID THROTTLE VALVE FOR ADJUSTABLY CONTROLLING THE MOVEMENT OF SAID ACTUATING MEANS IN OPPOSITION TO SAID PRESSURE EXERTING MEANS FOR INCREASING SAID PUMPING STROKE IN ACCORDANCE WITH OPENING OF SAID VALVE.

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