US 3077118 A
Description (OCR text may contain errors)
Feb. l2, 1963 F. H. RoBBlNs 3,077,118
VARIABLE DISPLACEMENT PUMP MECHANISM Filed April 30, 1958 2 Sheets-Sheet l M6/QM A TTOPNEY Feb. l2, 1963 F. H. RoBBlNs 3,077,118
VARIABLE DISPLACEMENT PUMP MECHANISM Filed April 30, 1958 2 heats-Sheet 2 IN VEN TOR.
A TTO/VEV United States Patent O 3,077,118 VARIABLE DISPLA'CEMENT PUMP MECHANISM Frank H. Robbins, Flint, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Apr. 30, 1958, Ser. No. 731,939 4 Claims. (Cl. 74-60) This invention relates to a fluid pump of the variable displacement type and more particularly to such a pump of the wobble plate type. p
Pumps of the aforementioned type generally include a plurality of plungers which arev reciprocated by the oscillation of an inclined wobble plate to produce a desired pressure in the pumped fluid; :the linclination of the wobble plate being adjustable to vary Ithe pump stroke and thereby displacement of the pump per operating cycle or per unit time. Such pumps are particularly adapted for use in systems requiring a relatively constant source of fluid Vunder a predetermined pressure since they can be accurately adjusted to vary the displacement of the pump by adjusting the tilt angle of the wobble plate. In high pressure sensitive systems such as automotive fuel injection systems, however, such pumps must necessarily have both a high degree of pressure control accuracy `and a relatively long life free from mechanical failures.
The invention contemplates an improved wobble plate adjusting mechanism for such uid pumps which is of a rugged construction adapted to provide a .long troublefree life and which is capable of being very accurately controlled by pressure controlled devices subject to the varying conditions in the associated equipment. The invention features a Itransformation of the eccentric load imposed on the rotating'wobble plate to a load parallel to and through Ithe axis of the pump driving shaft thus allowing relative freedom of adjusting movement and minimizing frictional losses between the several elements of the adjusting mechanism. In the illustrative embodime-nt, a displacement varying mechanism constructed in accordance with the invention is shown and described as adapted for use in a fuel pump for an automotive engine of either `the carbureted and fuel linjection types. However, the invention is considered to be applicable generally to pumps of the type described which may be adapted for other uses.
The foregoing and other features, advantages and objectives of the invention will become more apparent from the following description of the illustrative embodiment thereof, having reference to the accompanying drawings, in which:
FIGURE l is a sectional View of a pump constructed in accordance with the invention and taken substantially on the line 1-1 of FIGURE 2;
FIGURE 2 is an elevational end view of the pump of FIGURE l; and
FIGURE 3 is a sectional View 4taken substantially on the line 3-3 of FIGURE 2.
The pump shown in FIGURE 1 includes a housing member having a cylindrical portion 1l. closed at one end thereof by an integrally `formed end plate 12 which carries a central hub 14. A bearing 16 is mounted within hub 14 and receives one end of a drive shaft 18 therein. rllhe drive shaft 18 extends through the housing and into a bearing 29 which is secured in pump end cover 22. Intermediate housing 10 and cover 22 are a plurality of plates extending transversely of the pump housing. These plates include a plunger guide plate 24, a pressure chamber plate 26 having inlet and outlet ports therein, and an inlet and outlet valve and manifold plate 28. A plurality of bolts 30 secure cover 22 and plates 24, 26 and 28 to the housing 10. In order to properly assemble the plates in relation to the remainder of the 377,li8 Patented Feb. 12, 1963 pump, the cover 22 may be provided with an axially extending hub 32 on which the pla-tes 24, 26 and 28 are piloted. A key or other suitable means, not shown, may be used to permit assembly of the plates only when they are in proper alignment relative to each other and to cover 22. Bolts 34 fasten the plates to the cover in order to permit removal and assembly of the plate and cover group as a unit. The housing, plates and cover are separated and sealed by suitable gaskets positioned between adjacent elements.
The cover 22 is provided with an inlet passage 36 and an outlet passage 38. An annular groove formed in the upper side of the plate 28 cooperates with the underside of the cover 22 and the gasket interposed therebetween to form an inlet manifold chamber 4d which is connected through ythe gasket to the cover inlet passage 36. Plate 28 is also provided with a second annular groove opening on the lower side plate thereof which intersects a plurality of pressure outlet recesses 43 formed therein and cooperates with the upper side of the plate .26 and the gasket interposed therebetween -to form an annular outlet manifold chamber 42 concentric with and larger in diameter than the inlet manifold chamber 40. An outlet passage 44 connects outlet chamber 42 with the cover outlet passage 38 through a check valve 4S.
The plate 26 is provided with a plurality of pressure chambers 46 and an inlet passage 48 and an outlet passage 50 for each of the pressure chambers. Each of the outlet passages 50 is controlled by an outlet. check valve 52 which is mounted in one of the recesses 43 formed between the plates 26 and 2S. Each of the inlet passages 48 is controlled by an inlet check valve .54 which is mounted in an inlet chamber 55 formed intermediate the plate 26 and recesses provided therefor in the lower side of plate 28.
The plunger guide plate 24 has a plurality of cylinders or bores 56 therethrough which are adapted to reciprocably mount pump plungers or pistons 5S. Each of the cylinders 56 are in alignment with an inlet passage 48 and an outlet passage Si) and a pressure chamber 46 formed in the plate 26. The gasket between plate 24 and plate 26 extends between each of the pressure chambers 46 and the cylinders 56 to provide a plurality of diaphragm portions 69, each of which is engaged on its lower side by one of the pistons 5S and on its upper side by a diaphragm return spring 62. Thus, each. of the diaphragms 60 is reciprocated to provide a pumping action when the pistons 58 are reciprocated Within their respective cylinders 56.
Each of the pistons 58 has a plunger arm 64 extending from its lower surface and terminating in a rounded end 66. Individual sockets 68 are formed within a wobble plate or plunger actuating ring 70 and are adapted to` receive and thrustably engage the plunger ends 66. The ring 70 is mounted on the outer race of an anti-friction type bearing 72 and is retained from rotation by a ballheaded key or guide member 65 which is carried by and extends longitudinally from the underside of plate 24 and slidably engages the side walls of a radial. slot formed in lthe ring 70. The inner race of the bearing 72 is secured to a hub 74 which spacedly embraces the drive shaft 18 yand is formed integrally with a rotatably driven stroke control lever member 76.
As best seen in FIGURE 3, an enlarged section 73 is formed on the drive rshaft 1S immediately below the` reduced diameter portion thereof which passes through the hub 74. This enlarged section carries a driving platform or member 82 which is drivingly connected thereto by a pin 80. The stroke control lever member 76 is pivotally hinged at one side of driving member 82 -by a hinge pin 84. Thus, rotation of the driving member 82 translates a-ny inclination of the stroke control lever 76 into an oscillatory or swinging movement of the plunger actuating ring 70 thereby effecting the pumping stroke of the individual plungers with resultant flexure of the diaphragms ott to pump lluid to and from their respective pressure chambers 46. lt should be noted that the peripheral surfaces of the pistons S are semicircular in cross-section to permit cafnting of the several pistons in their respective guide bores 56 to accommodate for lateral displacement of the plate 70 relative to the axis of the pump due to its angular adjustment about the pivot 84. On the down stroke, fluid is drawn through inlet passage 36, annular manifold chamber 40, the inlet check valve 5d and through the inlet pasage 48 to the pressure chamber. On the up stroke of the piston and diaphragm, the inlet valve 54 is closed and outlet valves 45 and 52 are opened, permitting the pressurized fluid to flow through the outlet passage Sil to the annular manifold chamber 42 and to be delivered to any desired point from outlet passage 38.
Adjustment of the inclination of the stroke control lever 76 and thereby the stroke of the individual pump plungers is varied by an adjusting mechanism including a camshaft 90. The camshaft 90 is rotatably mounted in the housing 19 and extends transversely thereof in spaced parallel relation to the drive shaft 18. Intermediate its ends the camshaft 9d is provided with a cam surface 92 which thrustably engages one end of a lever 94. The lever 94 is pivotally mounted by a pin 96 carried by the housing member l@ and has an aperture 98 therein which spacedly embraces an enlarged portion 100 of the drive shaft 18. This enlarged portion of the shaft 18 thrustably engages the inner race of the shaft mounting bearing 16. The camshaft 9o is adapted to -be rotated by an actuating lever 83 which is secured to an end thereof projecting from the housing member. The lever S8 may be actuated by any suitable control mechanism responsive to one or more engine operating conditions such as speed or manifold pressure or vacuum. The resultant rotation of the camshaft 90 causes the cam surface engaging end of the lever 94 to be raised or lowered accordingly. Two cam lugs or bosses 192 are formed on the lever 94 on diametrically opposite sides of the drive shaft and transfer this movement of the lever 94 to a cam follower ring 194. The ring 104 embraces the shaft 1S immediately above its enlarged portion 1th) and carries the outer race ltloa of an anti-friction bearing 106. When the several elements of the displacement controlling mechanism are in their 11o-stroke positions, as shown in FIGURES 1 and 3, the ring 104 rests on the upper annular shoulder formed by the enlarged portion 14N? of the shaft and tends to rotate with the shaft 18. However, upon stroke varying movement of the lever 94, the ring 104 is carried out of thrust engagement with this shoulder and the cam lugs of the stroke control lever 94 tend to frictionally restrain the cam follower ring from rotation with the shaft. The inner race 1Mb of the bearing 106 carries a hub portion S of a yoke member 1MB. Two cam lugs 112 extend longitudinally from the hub portion 108 and thrustably engage two mating bosses or lugs 75 formed on the underside of the stroke control lever 76 in diametrically flankin relation to the shaft 18. The lugs 112 also slidably engage two flat surfaces 83 formed on diametrically opposite sides of the hub of the driving platform member 82 thus providing a driving connection between the yoke member 116` and the drive shaft 1S.
It will thus be seen that any rotation of the camshaft 90 from its position shown in the drawings is translated into angular adjustment `of the stroke control lever which, as indicated above, imparts a wobble or oscillatory movement to the plunger actuating ring 70 upon rotation of the shaft 18 thereby causing the piston or plungers 5S to reciprocate. The loads imposed Von the'inclined actuating ring'and stroke control lever by the individual pumping actions of the several pistons are inclined to and radially offset from the axis of the shaft 18. Thus the combined pumping action of the several pistons imposes an eccentric resultant load on the plunger actuating ring. This eccentric load rotates with the drive shaft and is transformed through the abovedescribed displacement controlling mechanism of the invention to a load parallel to and through axis of the shaft, being transferred through the lugs of lever 76, the lugs 112 of yoke member 110 and the bearing 196 to the lugs 102 of the casing mounted lever 94.
From the foregoing description, it will be seen that the several objectives of the invention are accomplished in the preferred illustrative embodiment wherein minimum deflective and frictional loads are imposed on and between the several elements of the displacement varying mechanism.
While the foregoing description has been restricted to one illustrative embodiment of the invention, it will be obvious to those skilled in the art that various modifications might be made therein without departing from the scope and spirit of the inveniton, as dened in the following claims.
1. In a fluid pump having a plurality of cylindrical bores, displacement varying control means comprising a plurality of plunger members each having a head portion thereon reciproca'bly mounted in each of said bores, the periphery of said plunger head portions each being spherical to permit limited angular movement of the plunger with respect to its mounting bore, means operable to effect controlled reciprocation and oscillation of each of said plungers, said means including an actuating ring pivotally connected to each of said plungers and tiltable to control the strokes of the plungers, a rotatable drive shaft, a first lever member embracing said shaft and rotatably mounting said actuating ring and mounted for rotation with said drive shaft and for pivotal movement about an axis spaced from and extending transversely of the axis of said drive shaft, said iirst lever having thrust bearing surfaces extending laterally of its pivotal axis and spaced on diametrically opposite sides of said shaft, a second lever member embracing said shaft and pivotally mounted in longitudinally spaced relation to said .lirst lever member and having thrust bearing surfaces thereon extending laterally of its pivotal axis and spaced on diametrically opposite sides of said shaft, a rst thrust member slidably mounted on and adapted to be driven with said shaft, said first thrust member having diametrically opposite, longitudinally extending portions thrustably engaging vthe bearing surfaces of said rst lever member and defining a line of engagement passing substantially diametrically through said shaft and parallel to the pivotal axis of said second lever. a second thrust member slidably mounted on said shaft and rotatable with respect thereto, said second thrust member rotatably mounting said first thrust member and being in thrust engagement with the bearing surfaces of said second lever member and defining a line of engagement passing substantially diametrically through said shaft and parallel to the pivotal axis of said second lever, and control means operable to effect movement of said second lever member thereby shifting said thrust members longitudinally of said drive shaft to effect a corresponding stroke controlling movement of said first lever member and said actuating ring.
2. ln a variable displacement uid pump having a plurality of cylindrical bores, displacement effecting means comprising a plunger member reciprocably mounted in the open end of each of said bores and having a head portion thereon, the periphery of e-ach of said plunger head portions being spherically formed to permit limited angular movement relative to its respective mounting bore, and means operable to eifect controlled reciprocation and oscillation of each of said plungers, said means including an actuating ring pivotally connected to each of said plungers and tiltable to control the stroke of the plungers, a drive shaft rotatably mounted in said housing, a lever member embracing said shaft and rotatably mounting said actuating ring and mounted for rotation with said drive shaft and for pivotal movement about an axis spaced from and extending transversely of the axis of said drive shaft, and control means including a yoled thrust member slidably mounted on said shaft and thrustably engaging said lever member on diametrically opposite sides of said shaft and dening a line of engagement therebetween parallel to the pivotal axis of said lever, said thrust member being operable upon controlled movement thereof longitudinally of said drive shaft to eiiect stroke controlling movement of said lever member and of said actuating ring.
3. ln a pumping mechanism having a plurality of plungers reciproca'oly mounted in a housing member and actuated by a ring tiltable to control the stroke of the plungers, means for controllably tilting said actuating ring including a drive shaft, a driving member secured to and extending radially from said shaft, a first lever member embracing said shaft and pivotally mounted on said driving member about an axis spaced from and extending transversely of the axis of said drive shaft, said iirst lever member rotatably mounting said actuating ring, a second lever member embracing said shaft and pivotally mounted within said housing :member in longitudinally spaced relation to said iirst lever member for movement about a stationary :axis spaced from and extending transversely of the axis of said drive shaft, a first thrust member sldably mounted on said shaft and adapted to be driven by said driving member, said rst thrust member thrustably engaging said first lever memer on opposite sides of said shaft parallel to the pivotal axis of said lrst lever member, a second thrust member slidably mounted on said shaft and rotatable with respect thereto, said second thrust member rotatably mount ing said first thrust member and being in thrust engagement with said second lever member on opposite sides of smd shaft parallel to the pivotal axis of said second lever member, and means operable to eiect movement of said second lever member thereby controllably shifting said thrust members longitudinally of said drive shaft to elect a corresponding stroke controlling move ment of said Vrst lever member and of said actuating ring,
4. 1n a pumping mechanism having a plurality of piungers mounted for pumping reciprocation Within pumping chambers defined by a housing member and an actuating ring operably connected to each of said plungers, means for controilably tilting said actuating ring to effect pumping reciprocation of said plungers, said means including a drive shaft, a first lever member embracing said shaft and rotatably mounting said actuating ring, said lever member being drivingly connected for rotation with said drive shaft and mounted for swinging movement about an axis spaced from and extending transversely of the axis of said shaft, a second lever member embracing said shaft and pivotally mounted Within the housing member for swinging movement about a stationary axis spaced from and extending transversely of the axis of the drive shaft, means operable to effec-t movement of said second lever means, and thrust means slidably mounted on said shaft and extending intermediate and thrustably engaging said lever members on diametrically opposite sides of said shaft on lines substantially parallel to the respective pivotal axes of said levers, said thrust means being operable upon swinging movement of said second lever member to effect a corresponding stroke controlling movement of said first lever member and of said actuating ring.
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