US3019738A - Fluid pump - Google Patents

Description

J. ZUBATY FLUID PUMP Feb. 6,

Filed May 6, 1957 W2 Y j- Z @Mw w f @y 1 w wrom Patented Feb. d, l

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3,019,738 FLUD PUB/E Joseph Zubaty, Flint, Mich., assigner to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed May 6, 1957, Ser. No. 657,449 2 Claims. (Ci. 10S-15u) The invention relates to a fluid pump and more particularly to a pump in which the delivered uid volume may be laccurately varied over a wide range. Pump delivered volume variations are preferably obtained by adjusting the stroke of diaphragm actuating plungers. The pump plungers may be actuated by a cam mechanism which may be accurately adjusted to vary the plunge-r strokes. In order to provide additional volume control accuracy, each plunger is provided Lwith an individual diaphragm which forms one wall of a pump chamber. Each diaphragm is flexed a predetermined amount depending upon the plunger stroke. The side of the diaphragm forming the pump chamber is preferably concave and the head of the pump plunger which contacts and flexes the diaphragm is preferably rounded to provide small rate of volume change when a short stroke is used and a proportionally greater rate of volume change as the stroke is increased. Such a construction is especially useful in fuel pumps where it is desirable to obtain a proportionally larger pump output for a slight increase in the stroke of the pump plunger, thereby attaining full power of the engine under load. The curved shape of the plunger head lalso permits minimum diaphragm stress.

The stroke of the plungers may be adjustable by a worm and pinion mechanism in combination with a spring and stroke adjusting lever. The lever is preferably connected to move a plunger actuating cam from a zero lift position to a position corresponding to the desired plunger stroke.

In the dra ying:

FIGURE l isa cross section view of a pump embodying the invention;

FIGURE 2 is a View taken in the direction of anrows 2 2 of FIGURE l, with parts broken away and in section; and

FIGURE. 3 is a View of the pump stroke adjusting mechanism and is taken in the directions of arrows 3--3 of FGURE l.

The pump may 'be provided with a lower body iti and an upper body i2 which are joined to form la pump housing. Lower body 1li may have an external boss 14 with a bearing i6 retained therein. Pump drive shaft 18 may be mounted for rotation in bearing 16 and extend therethrough into the housing formed by the upper and lower bodies. The upper end 26 ot' drive shaft i8 may be journalled within bearing 22 which is supported in the pmnp upper body LB. Pump lower body lil is 'also preferably provided with an inner boss 1M- which is axially aligned with boss i4 and is internal-ly threaded at 26 to receive the threaded hub 28 of a stroke adjusting pinion Sii. An annular recess 32 may be provided between bosses -l and 24 to permit pinion hub 28 to be threaded into boss 24 beyond the inner edge thereof.

Pump upper body 12 may be provided with an annular depending plunger support ring 34 which is concentrically located with respect to pump drive shaft 18. Ring 34 has a plurality of radially extending plunger cylinders in which pump plungers 36 may be received and reciprocated.

The length of the reciprocating strokes of plungers 36 is determined by the radially offset position of plunger actuating cam 33. Cam 38 is nonro-tatably secured to drive shaft 18 and is permitted to be diametrically displaced to vary the plunger stroke and obtain the desired plunger stroke. Drive shaft 18 has an enlarged section i0 through which a diametrically extending cam positioning lever pin 42 extends. The upper portion ed of enlarged section d@ is provided with oppositely disposed tl-at surfaces 41 which are positioned in planes parallel to and spaced from the axis of the drive shaft. Tlat surfaces d5 terminate at their lower sides at radially disposed cam support surface e8. Cam 38 is provided with Ia center slot which opens at cam end 52 to give cam 38 a generally U-shapcd appearance. The closed cam end 5d is preferably eXtei-iorly formed as a semi-circle or other curved shape to provide a cam surface for 'actuating plungers 36. Cam 3S is received about drive shaft portion 44 and the inner surfaces of the cam legs S3 and 55 which detine slot Si) are in sliding engagement with the at surfaces i5 of the drive shaft. Cam slot 50 extends a sufficient distance toward cam closed end 54 to permit the cam `to be positioned to provide zero lift of the plungers 36. A stroke limiting plate 56 is secured around shaft 1S between the cam 3S and bearing 22. Plate 55 is circular and is -engageable with the inner ends S8 of plungers 35. No reciprocating motion is obtained when plunger ends 5S engage plate 56 and the plungers 'are not permitted to reciprocate radially inward beyond that plate. Each of plungers 36 maybe provided with a rounded end 66 which is aligned radially with cam 3ft and is contacted by that cam when drive shaft 18 is rotated and the cam is not in a zero lift position. As drive shaft 18 rotates, the curved cam end 54 successively engages each of the plungers 36 at a point on round ends 5!) and causes radially outward reciprocating movement of each plunger.

Cam 33 is preferably adjusted by means of a spring and lever linkage system including crank ann levers 62 and 54 which are oppositely disposed about drive shaft enlarged section 4t! and pivotally mounted on either end of pin 42. Cam adjusting pinion 3? may be provided with a thrust ring 66 on its upper end which is engageable with crank arm lever following ends or arms Gti and 76. The cam positioning ends or arms 72 and 74 of levers 62. and 64 may be rounded and received within cam slots .76 and 78 formed on the outer side of each cam leg 53 and 55. Crank arm levers 62 'and 64 are biased into engagement with thrust ring 66 and cam 33 by torsion springs Sii and 32. Springs Sti and 82 are provided with center loops 34 and 86 which respectively encircle the ends of pin 42. The upper ends i8 of the springs are in engagement with the lower surface of enlarged drive shaft section on which cam 32 is supported along surface 4S. The lower ends 92 of the springs are hooked about lever following ends 68 and 70 to bias those ends away from enlarged drive shaft section 90. The crank arm levers are therefore biased to rotate in a clockwise direction as viewed in FlGURE 1 thereby keeping follower ends 68 and 70 in constant engagement with thrust ring 65 and biasing cam 38 toward a Zero lift position.

In order to adjust the position of levers 62 and 64, pinion 36 is moved axially relative to drive shaft 18. This movement may be accurately controlled by turning worm gear 9d, which is in driving engagement with the teeth 96 of pinion 30. When worm gear 94 is rotated, pinion 3l) is also rotated and the pinion hub 2S is screwed inwardly or outwardly relative to boss 24, thereby moving the pinion Sil and thrust ring 66 axially. The axial movement of pinion 3@ `and thrust ring 56 pivots crank arm lever follower ends 68 and 7() arcuately about pin 42. Lever cam positioning ends 72 and 74 are also moved arcuately about pin l2 and have a component of motion parallel to cam 3R. This component of motion causes cam 38 to move radially inward or outward to adjust the stroke of plungers 36. When pinion 30 is moved upward, the plunger stroke is increased and when it is moved downward the plunger stroke is decreased until it reaches Zero.

The outer ends 97 of plungers 36 are preferably rounded and formed as mushroom heads. Each of the plungers is in axial alignment with a pump diaphragm 98 and is engaged with the hat surface of these diaphragms over 'an area which is substantially centered about the artis` ot' each plunger 36. Each diaphragm 98 is preterably formed with a 4diaphragm mounting rib 102 which also acts as a gasket. A cylindrical boss 104 extends inwardly from diaphragm rib 102 and terminates at the diaphragm surface 180. The pump upper body 12 is provided with a plurality of diaphragm receiving openings 1.06 through which diaphragm bosses 104 extend. The diaphragms are held tightly in place by caps 103 which contain discharge passages 110 and ball check valves 112. Outlet lines, not shown, are attached to each of the caps 108 through bushings 114. Caps 10S also include intake passages 116 which are aligned with passages 118 formed in the end of pump upper body 12. Diaphragms 98 are provided with concave center sections 12h which are axially positioned within bosses 104 and cooperate with caps 108 to form pumping chambers 122. The pumping chambers 122 are thus each provided with a spherical wall which has a curvature opposite to the curvature of the rounded ends 97 of plungers 38. Due to the rounded form of the plunger ends 97 and the concave shape of the pumping cylinders 122, the plunger stroke required for Aa given volume of iiuid pumped is larger at a lower volume output than at higher volume delivery conditions. The stroke-volume ratio is therefore a non-linear variation which is a useful result in fuel pumps Where it is desirable to obtain a proportionally larger pump output for a slight increase in the stroke of the pump plunger.

Distribution passages 11S are connected with discharge passages 110 adjacent pumping chambers 122. Passages 118 are intermittently provided with fluid under intake pressure conditions 'by rotary distributor valve 124. Valve 124 be frusto-conieal in cross section and is preferably provided with Ia drive tang 126 which is received within a slot 128 formed in the upper end of drive shaft 18. An upper body pump cap 130 may be secured over valve 124 and have an inlet passage 132 formed therein. If desired, an adapter 134 may be provided in order that various inlet connections may be made. Adapter 134 may be recessed at 136 to receive distributor valve spring:

138. Spring 138 is held in compression between valve 124 and adapter 134 to bias the valve against its conical seat in the pump upper body 12. Inlet passage 132 connects with valve passage 140 which extends axially into valve 124. Valve distributing passage 1,42 extends ra* dially outward from passage 140, and, when valve 124 is properly seated, may be successively aligned with each of the distributing passages 118.

The stroke and consequent delivery volume of the pump may be adjusted either prior to operation of the pump or during pump operation. Worm gear 94 may be provided with an extension shaft, not shown, passing through the side of the pump housing for -this purpose.

When drive shaft 18 is rotated, distributor valve 124 is also rotated to successively permit inlet fluid flow through the passages 132, 140, 118, `and 116 to pressure chamber 122. The pressure chambers and the passages connected thereto are thus illed with liuid. Distributor valve 124 is so timed relative to the angular position of cam 38 that passage 142 is no longer aligned with passage 11S when the plunger 36 actuating the pressure chamber to which that particular distributing passage connects is out- Wardly reciprocated. When plunger 36 is moved radially outward under action of cam 38, its rounded head 96 exes diaphragm 98. Plunger head 97 contacts diaphragm surface 1110 over an increasing area. as the stroke is increased. Pressure chamber 122 is correspondingly decreased in volume and the pressure built up in that chamber and passages 110, 116, and .1.13 is suicient to open ball check valve 112 and permit iiow of Enid under' pressure to the pump outlet line connected to bushingV 114.

The same operation is carried out in each of the pumping units as the cam distributor valve 124 and cam 38 are rotated by drive shaft 18. Ball check valve 112 may be 'biased to a closed position by a spring 144 which will determine the minimum pressure which may be delivered through the pump outlet lines. The volume pumped by the various plungers and diaphragms is thus accurately controlled by controlling the stroke of the plungers 36. The volume of fluid pumped maybe varied from zero to .a maximum determined 4by the maximum stroke of cam 33 by providing a simple 'and reliable external adjustment. This adjustment may `be made as part of a control system to obtain a desired volume at all times or may be .manually controlled.

What is claimed is:

1. In a uid pump having a housing `and drive shaft, means for varying the volume of fluid pumped compris ing a reciprocable plunger having a curved head at one end, a diaphragm of substantially rectangular cross section mounted in said housing land including a section having a continuously concave surface defining one wall of a pumping chamber and a at surface engaging said plunger curved head, said plunger curved head having sub v stantially the same projected area as said diaphragm confcave surface, and stroke varying means drivably engage- -able with said plunger and driven by said drive shaft for reciprocating said plunger whereby said plunger is caused `to flex said diaphragm, the stroke varying means thereby cooperating with said diaphragm and said plunger head during the pump operation to provide a non-linear strokevolume ratio.

2. In a pump, a non-linear volume delivery control comprising a pump housing, a diaphragm of substantially Irectangular cross section received Within said housing, a cap for said diaphragm, said cap and said diaphragm cooperating to define 'a pumping chamber, said diaphragm having a spherically and continuously concave wall deining one side of said pumping chamber and a substantially dat wall opposite said concave wall, a diaphragm exing plunger having a spherically convex end of substantially the same area as said diaphragm and engageable with said flat Wall opposite said concave Wall and driven means engageable with said plunger for 'adjustably reciprocating said plunger and thereby varying the plunger end-todia phragm engageable area to non-linearly control pump volume delivery in relation to plunger reciprocating stroke.

References Cited in the le of this patent UNITED STATES PATENTS 285,477 Garsed Sept. 25, 1883 2,078,835 Brissou Apr. 27, 1937 2,267,280 Kuhnel Dec. 23, 1941 2,311,939 Goode et al. Feb. 23, 1943 2,393,175 Laskey Ian. 15, 1946 2,491,230 Theis Dec. 13, 1949 2,569,900 Nevin etal Oct. 2, 1951 2,632,339 Lane Mar. 24, 1953 2,690,295 Rand Sept. 28, 1954 2,710,629 Price June 14, 1955 2,730,131 Asp et al. Jan. 10, 1956 2,871,846 Zimmerman Feb. 3, 1959 2,890,656 `Kohtaki lune 16, 1959 2,928,426 Taylor Mar. 15, 196() FOREIGN PATENTS 659,791 France Feb. 11, 1929

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