US2878755A - Variable displacement pump and pressure responsive control means therefor - Google Patents

Description

March 24, 1959 B. E. o'coNNoR ETAL 2,878,755

VARIABLE DISPLACEMENT PUMP AND PRESSURE RESPONSIVE CONTROL MEANS THEREFOR Filed May 15 1950 A2 Sheets-Sheet l gw l, l

March 24, 1959 B. E. o'coNNoR ErAL 2,878,755

VARIABLE DISPLACEMENT PUMP AND PRESSURE RESPONSIVE CONTROL MEANS THEREFOR Filed May 13, 1950 2 Sheets-Sheet 2 United States Patent O VARIABLE DEPLACEMENT PUMP AND PRES- URE RESPONSIVE CONTROL MEANS THERE- Bernard E. UConnor, Buffalo, and Alfred G. French, East Aurora, N.Y., assignors to Houdaille Industries, Inc., Detroit, Mich., a corporation of Michigan Application May 13, 1950, Serial No. 161,754

Claims. (Cl. 1031-120) The present invention relates to improvements in variable displacement pumps and is `more particularly concerned with novel structure and relationships in such pumps for contro-lling pump displacement.

An important object' of the present invention is to provide improvements in variable displacement `pumps for automatically as well as selectively adjusting pump displacement.

Another object of the invention is to provide improved means for controlling variable displacement pumps responsive to pump-created pressure and selectively adjustable for varying the pump pressure responsiveness thereof.

A further object of the invention is to provide novel pressure responsive control valve means and means for selective modification of its pressure responsiveness for controlling the displacement of a variable displacement pump.

Yet another object of the invention is to provide improved control valve means for variable displacement pumps normally responsive to predetermined pumpcreated pressure above a mean pressure to maintain the pressure substantially constant by varying the pump displacement, and including means controllable from a point externally of the pump to vary the pressure responsiveness of the valve means.

Still another object of the invention is to improve the general construction of variable displacement pumps.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of a preferred embodiment thereof taken in conjunction with the accompanying drawings, in which:

Figure 1 is an elevational view of one side of a variable displacement pump of a type especially suitable for use in a transmission for an automotive vehicle or the like;

Figure 2 is a sectional detail view taken substantially on the line II--II of Figure l through the face plate of the pump assembly shown in full in Figure l;

Figure 3 is a side elevational view of the opposite side of the pump from that shown in Figure l and with the face plate removed to reveal internal mechanism of the pump; and

Figure 4 is a sectional detail view taken on substantially the line IV-IV of Figure l.

By way of illustration there is shown in the drawings a variable displacement pump of the sliding vane type and in the particular embodiment shown adapted for use in the transmission system of an automotive vehicle. The pump comprises a casing housing a pump rotor 11 which has a uniformly spaced series of radial peripherally opening slots 12 within which are operably disposed sliding reciprocable vanes 13. The sides of the rotor 11 are inset at predetermined distance from its periphery at both sides to accommodate concentric rings 14 in engagement with the inner ends of the vanes 13 and functioning to maintain'the outer ends of the vanes or blades on a predetermined diameter. A central bore may be provided through the rotor 1l provided with spline teeth 15 by which the'rotor is adapted to be assembled for rotation upon a splined shaft in a transmission assembly.

A circular pump chamber 17 concentric with the control rings 14 and of a diameter to be constantly engaged by the outer tips of the vanes 13 is provided by a displacement control member or modulator 18. In the present instance the modulator 18 is of the reciprocablyv guided type having opposite parallel at sides or edges 19 slidably engaging parallel bearing walls 20 defining opposite sides of a modulator control chamber 21 provided in an intermediate casing member or ring 22. By preference the housing ring 22, the modulator 18 and the rotor 11 are of approximately the same thickness, thatis their broad faces are disposed in approximately the saine planes while opposite facing plates 23 and 24 complete the housing or casing -10 enclosing the pump and more particularly affording closures for the pump chamber 17 and the modulator chamber 21. In assembly, suicient sliding clearance is afforded for the pump rotor 11 and the modulator 18 after the facing plates 23 and 24 have been secured to the opposite faces of the intermediate casing member 22 so as to permit free rotation of the rotor 11 and slidable reciprocation of the modulator ring 18.

As best seen in Figure 4, the facing plate 23 may be provided with a central hollow hub 25 provided with internal splines 26 for connection of a spline member in the transmission with which the unit may be used. A iiuid passage 27 leads from the splined bore to the outside of the casing. The diameter of the spline bore iny the boss 25 may be smaller than the diameter of the spline bore in the pump rotor 11. Clearance passage for the shaft to which the pump rotor is splined is provided by a concentric bore 2S in the facing plate 24.

Rotation of the rotor 11 in operation is intended tol be clockwise as viewed in Figure 3 so that hydraulic liuid from any appropriate source is drawn through an arcuate inlet duct or port 29 by action of the rotor blades 13 at the low pressure side of the pump and displaced through an outlet duct or port 30 at the high pressure side of the pump. Both of the ports 29 and 30 are preferably located in the inner face of the facing plate.

23. As best seen in Fig. l, an inlet passage 31 leads-to the inlet port 29 while a discharge or high pressurey passage 32 leads from the high pressure port 30.

At the beginning of operation, at least, it is desirable that the pump displacement be at maximum, and for this purpose the modulator 18 is preferably biased to dispose the pump chamber 17 in maximum eccentric pumping relation to the rotor 11 by a spring 33 which may be in the form of a coiled compression biasing spring seated at one end in a shallow depression 34 in one end of the modulator and at its other end in a socket-like recess 3S in the opposing wall defining the modulator chamber 21 in the intermediate casing ring 22.

The principal function of the biasing spring 33, which may be of relatively light weight and which need not be of any critical load or compression strength, is to assure that the modulator 1S will normally be, at least at the beginning of operation, in a position of pump chamber eccentricity with respect to the pump rotor 11. As a result, when the pump is started, maximum displacement will occur.

Means are provided for automatically adjusting thev tically adjustable control valve structure 37 (Figs. 1

and 2) operable to control the application of pump- Patented Mar. 24, 1959 created pressure for directly adjusting the position of the modulator 18 within the modulator chamber 21 for establishing and maintaining such a relationship of the pump chamber 17 to the pump rotor 11 that amean pump o utput pressure selected,within a.variable range is maintained `as desired;

In a convenient, economical and highlyr etiicient form the control valve assembly 37 includes a reciprocable plunger valve member 3S operatively slidably disposed within a` bore 39 in the pump housing 1i), and in the present instance located in the facing plate 23 which for this, purpose is provided with a thickened portion or embossment 40 at one side of the hub 25. A salient advantage of such location of the valve bore 39 resides in that all piping can be avoided for effecting communication between the fluid system of the pump and the modulator chamber 21 by way of the control valve. All such communication can thus be elected by passages or ducts in the housing 10. This is a valuable feature where space isat a premium and a compact unit without external ducts, tubes or piping is desired, such as in an automotive transmission. This arrangement also avoids the liability of accidental blockage or restriction of the intercommunicating fluid passages as often occurs in sysn tems including tubes serving as fluid passages and thus liable to damage during installation or servicing of the apparatus, or otherwise. Furthermore, frictional pressurelosses are greatly reduced because of the relatively more direct, short passage communications that can be attained through the ducts and bores providing uid passage within the walls of the housing 10.

By preference, the control valve housing bore 39is so disposed that direct communication with the high pressure or discharge port of the pump is effective through alpassage bore 41 between the port 30 and one end portionpofwthe valve bore 39. In this way the adjacent end of the valve body 38 is subjected to pump pressure during operation. In order to assure constant exposure of the mentioned endl of the valve member to the high pressure, such end may -be provided with a reduced diameter or head end stop finger 42 engageable with a closure plug 43 by whichthe proximate end of the valve bore 39 is sealed off outwardly from the high pressure communication duct 41.

The valve-member 38 is normally biased in opposition` to. pump pressure, that is toward the head end ofthe valve, by means herein comprising a coiled compression spring44 actngagainst the opposite or rear end of the valve member and seated against a bottom or shoulder 45 at the inner end of the valve bore. For this purposi?,4 the length of the valve housing bore 39 is substantially longer than the body portion of the valve member 38.` The spring 44 is selected both as to length and tensioning qualities to resist, under load, movement of the valve member 38 in opposition to the spring with a predetermined static force. Thus, until the dynamic pressure of the pump-impelled uid attains a force in excess of the spring loading, the valve38 will be maintained in its fully biased position.

The relationship of the biasing spring 44 to the valve member 38 is such that when a mean pump output pressure value is exceeded, the pump pressure acting upon the head of the valve drives the valve in opposition to the spring for eiecting valve controlled communication with the modulator chamber 21 to effect shifting of the modulator and thus adjustment in the pump displacement and return to the mean output pressure. For this purpose, communication is effected between appropriate portions of the valve bore 39 and the modulator chamber 21.` Since during acceleration of the pump at the beginning `of operation or during operation at lower than the mean output pressure, itis desirable to have the modulator 18 in the position of maximum pump chamber eccentricityprelative to the pump rotor 11, initial communication between a sub-chamber 47 between the end of the modulator 18 engaged by the biasing spring 33 and the opposing wall detining the modulator chamber is effected with the high pressure side of the pump by way of a port or duct 48 (Figs. l, 2 and 4) leading from the valve bore 39 to a recess 49 in theperiphery of the facing plate 23 and communicating with a fluid passage channel .50 provided in the periphery of the intermediate housing member 22 running to a radially inwardly directed passage Sll entering the modulator sub-chamber 47. A housing member 10a about the casing 10 closes the rcces s49 and the channel 50. In the fullyV biased or at rest position of the valve member 38 an annular groove 52 in the valve member registers with the passage 48, while a plurality of annularly spaced longitudinally extending bores 53 in the head end portion of the valve member afford communication between the head end of the valve member and the channel 52. Thus, pump-created pressure less than and up to the mean pressure for which the valve member 38 is biased will be eiected through the communication passageway to the modulator sub-chamber 47 for acting on that end, namely the biased end of the modulator to assist the biasing spring 33 in maintaining the modulator in full eccentric position.

At the same time, all pressure is relieved from the opposite end of the modulator 18. At this end, the modulator is formed withy aattened stop portion 54 which engages a complementary flattened abutment portion 55 defining part of the wall of the modulator chamber in the intermediate casing member 22 (Fig. 3). l stop portion 54, the end portion of the modulator is recessed or set back' to provide a modulator sub-chamber 57. A bore passage 58 communicates with the sub-chamber S7 and with the valve bore 39 in a position to register with a peripheral annular communication groove 59 iu the valve member 38 communicatingby way oan annularly spaced set of longitudinal passages 60 with and through the end of the valve member 38 and thus with the biasing spring chamber in the bore 39 behind the valve member. A port 61 effects communication between the inner end portion of the valve chamber 39 and the low pressure or suction port 29 of the pump fluid` system. Thus, means are-provided in an eicient and simple manner for relieving the modulator of pressure at the end toward which it is` biased while the pump lis operating below a given mean operating pressure. It will be understood, of course, that preferred communication could be effected between the4 sub-chamber 57 and atmosphere at a sump or thel like, since the principal consideration is pressure relief.

When the pump-created pressure has attained the desired mean the valve member 38 is moved in opposition to the biasing spring 44 to a balanced position wherein,

the valve member 38 closes off the ports or passages 48 and4 58. This substantially locks the modulator 18 in its fully eccentric position.

Upon development'of pump `pressure in excess of the mean pressure desired,4 the valve member 38 is moved additionally in opposition to the biasing spring 44 until a pressure uid duct or port '62, which up to this time has been closed by the valve 38, is `opened to the high pressure side of the pump by registration of the high.

pressure groove A52 in the4 valve with the port 62. The pressure port or passage 62 communicates with the modulator sub-chamber 57 to exert pressure upon the contiguous end of the modulator 18 and shift the modulator toward a position of `less pump chamber eccentricity relative to the rotor 11. At the same time pressurerelief communication with the modulatorsub-chamber 47 is eiiected by opening of a port onpassage 63 upon registration of relief groove 59 in the valve member therewith to; effect communication with the recess 494 to which' thev passage 63 leads.l Thus, the modulator is quickly shifted and the desired mean output pressure re-established, the

valve member 38 ,returning nto. a port blocking` position Adjacent the i agarrarse as 4soonI as the desired mean pressure has been re-established.

It will thus be apparent that highly sensitive control automatically in response to pump-created pressure is afforded over the modulator 18 by response of the valve 38 to action of the biasing spring 44 and the dynamic pressure of the pump acting upon respective opposite ends of the valve member.

To accommodate situations where in the course of operation it is necessary to increase the mean pump output pressure during any particular interval, means are providedfor selectively imposing an increased biasing pressure upon the valve member 38 in addition to and supplemental to the biasing spring 44. To this end, a supplementary biasing plunger element or member 64 is slidably Vdisposed within a reduced diameter inward extension 65 fromv the valve bore 39 and concentric with the valve bore. Valve biasing engagement with the valve member 38 by the biasing plunger 64 is elTected through the medium of a rearwardly extending projection or stem 67 on the valve member directed into the spring 44.

When the control valve 38 is to function solely under the biasing inuence of the spring `44, the auxiliary biasingplungery 64 remains inert or free floating in the bore extension 65. However, when it is desired to increase the ybias upon the valve 38, fluid under pressure is introduced into the bore portion 65 through a passage 68 leading into a further reduced diameter portion or port 69 at the rear of the reduced bore portion 65. The passage 68 leads off through the casing face plate 23 and if desiredv onfthroug'h the outer housing or supporting membery a and communicates with any preferred source of uid under pressure which may be a separate source of fluidor may be the pressure uid displaced by the pump. In any event, any preferred additional biasing load may be imposed upon the valve 38 by the fluid pressure introduced behind the biasing plunger 64. For example, if the biasing spring 44 is rated at a loading of thirty pounds per square inch resistance to the valve 38, and it is desired to establish a mean pump output pressure of sixty pounds per square inch, then the pressure introduced behind the biasing plunger 64 will be sixty pounds per square inch. Of course, it will be clear that any other selected or additional pressure desired may be imposed upon the valve 3S through the plunger 64 by imposing the desired auxiliary biasing uid pressure upon the auxiliary biasing plunger 64.

The stem extension 67 of the valve member 38 also serves as a stop for limiting rearward or pressure induced movement of the valve member 38, so that under unusual pressure thrusts the valve member will not overrun the system of control ports leading to the modulator chamber. Accordingly, at the limit of pressure thrust movement of the valve member, the auxiliary plunger 64 comes to rest against a stop shoulder 70 provided at the bottom of the auxiliary reduced diameter auxiliary plunger bore 65. In this thrust limit position, of course, high pressure fluid from the pump will be conveyed by way of the passage 62 to the modulator sub-chamber 57 for driving the modulator toward a position of reduced pump chamber eccentricity.

i From the foregoing it will be apparent that the present iivention provides a variable displacement pump control arrangement that is not only highly sensitive for selective multi-stage pressure responsiveness within a large range, but also in any stage of selected or adjusted pressure responsiveness of the control valve mechanism is automatically adjustable for variable displacement of the pump to maintain a desired mean pumping pressure.

It will be understood that modications and variations may be effected without departing from the scope of the novel concepts of the present invention.

We claim as our invention:

1. In combination in control means for a variable displacement pump, a casing having a bore, a control aol valve plunger in r'said bore jecting the valve plunger at oneend to pressure fluid from the high pressure side of the pump, a spring in said bore operative on the valve plunger in opposition to the high pressure on the valve plunger, a stem projecting from the valve plunger past the spring, a reduced diameter` portion at the rear end of the bore, an auxiliary pressure plunger in said reduced diameter portion, said stem being engageable by said auxiliary plunger, and means for introducing pressure Huid into said reduceddiameter borey behind said auxiliary plunger for thrusting said auxiliary plunger against said stem and thereby supplementing the bias of said spring.

2. `In combination in control means for a variable displacement pump, a casing having a bore, la controlv valve plunger in said bore and means for directly Asubjecting the valve plunger at one end to pressure uid from the high pressure side of the pump, a spring in said the' high pressure on the valve plunger, a stem projecting from the valve plunger past the spring, a reduced diameter portion at the rear end of the bore, an auxiliary pressure plunger in said reduced diameter portion, said l.stem being engageable by said`auxiliary plunger, 'and means for introducing pressure tluid into said reduced diameter bore behindvsaid auxiliary plunger for thrusting said auxiliary plunger against said stem and thereby supplementing the bias of said springsaid auxiliary bore tghaving an inner generally axially facing shoulder against which the auxiliary plunger is` engageable as a stop toV limit movement of the valve plunger in opposition to the spring and auxiliary plunger.

3. In a variable displacementI pump construction, a

,fr casing ring dening a modulator chamber, a modulator ring member lin said chamber and cooperating at diametrically opposite sides withthe vwall of said ring dened chamber to divide 'the space in said chamber into opposite sub-chambers at respective diametrically opposite* sides of the modulator between said first 4mentioned diametrically opposite sides, said modulator having therein a pump chamber within which Va pump rotor and uid impelling means are adapted to operate, casing structure enclosing the opposite faces of said casing ring and the periphery of said casing ring, respective iluid inlet and outlet ports communicating through said casing structure with the pump chamber, said casing structure having a valve chamber therein, said casing structure having a passage leading from one of said sub-chambers to said valve chamber, said casing ring and said casing structure having a Huid passage leading to said valve chamber from the other of said sub-chambers, said casing structure having a further passage leading to said valve chamber from `said outlet port, and a valve member in said valve chamber responsive to uid pressure through said further passage to control the ow of pressure fluid from said further passage through said valve chamber into selectively the passages from said sub-chambers, said passage leading from said other of said sub-chambers to said valve chamber comprising in part a groove in the outer periphery of said casing ring and said groove being closed at the periphery of the casing ring by the surrounding casing structure.

4. In combination in a variable displacement pump, a casing defining a modulator chamber, a modulator adjnst ably movable in said chamber and cooperating with the walls defining said chamber to divide the modulator chamber into sub-chambers at respectively substantially diametrically opposite ends of the modulator, the modulator having therein a pump chamber, a pump rotor operable in said pump chamber and having means cooperating with the wall of the modulator defining the chamber to displace uid through the pump chamber, uid inlet and outlet ports communicating with the pump chamber, and means for controlling the position of the modulator in said modulator chamber comprising: a valve chamber proand' means for directly subs vided by the casing, respective passages leading from said sub-chambers to said valve chamber, a further passage leading from said outlet port to the valve chamber, a plunger valve reciprocable in said valve chamber and operable responsive to uid pressure communicated through said further passage to control delivery of pressure' uid from said further passage through said valve chamber selectively to said passages that communicate with said sub-chambers, a spring normally biasing said valve plunger in opposition to the pressure of uid delivered through said further passage, said valve plunger having a portion extending therefrom past the spring, a reciproeable plunger independent of the spring and reciprocable relative to the valve plunger but disposed in thrusting relation to said plunger, and means for subjecting the reciprocable plunger to uid pressure to drive the reciprocable plunger into thrusting relation to said portion for supplementing the bias of the spring in opposing pressure from the pump through said further passage, whereby to increase the bias load that must be overcome before the valve plunger will shift in opposition to the spring.

5. In a variable displacement pump construction comprising a casing structure defining a modulator chamber having movable therein a modulator cooperating with the walls defining the chamber to divide the chamber into respective sub-chambers at substantially diametrically opposite ends of the modulator, the modulator having therein a pump chamber cooperative with a pump rotor for displacement of uid through the pump chamber from an inlet port to an outlet port communicating with the pump chamber, the improvement which comprises: a reciprocable valve plunger, said casing having a valve chamber within which the valve plunger is reciprocable, respective passages in the casing communicating with an intermediate portion of the valve chamber, a pressure passage communicating with one end portion of the valve chamber and with the outlet port and impressing on one end portion of the valve pressure from the pump and for supplying pressure through said respective passages under the control of the valve plunger to said sub-chambers, additional passages leading from the valve chamber and communicating with said sub-chambers, a passage leading from the inlet port to the opposite end portion of the valve chamber for communication under the control of the valve plunger with said additional passages, a spring disposed between said opposite end portion of the valve chamber and the adjacent end portion of the valve normally biasing the valve toward said one end of the valve chamber, said opposite end of the valve chamber having a reduced diameter bore portion, a freely reciprocable biasing plunger in said reduced diameter portion, a stem on the valve adjacent to said biasing plunger and thrustingly engageable by the biasing plunger, and a passage leading into the inner end of said reduced diameter chamber portion for supplying iluid under pressure behind said biasing plunger to eirect valve biasing thrust of said biasing plunger against said stem supplemental to the bias afforded by said spring.

References Cited in the le of this patent UNITED STATES PATENTS 1,943,929 Rayburn Ian. 16, 1934 2,080,810 Douglas May 18, 1937 2,166,423 Clark July 1s, 1939 2,238,062 Kendrick Apr. 15, 1941 2,254,103 Douglas Aug. 26, 1941 2,391,323 Martin Dec. 18, 1945 2,433,484 Roth Dec. 30, 1947 2,490,115 Clarke Dec. 6, 1949 2,600,632 French June 17, 1952 2,600,633 French June 17, 1952 2,649,739 Huferd et al. Aug. 25, 1953 FOREIGN PATENTS 528,950 Great Britain Nov. 11, 1940 574,359 Great Britain Jan. 2, 1946

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