US3456593A

US3456593A - Variable capacity mechanism for fluid pumps and motors

Info

Publication number: US3456593A
Application number: US648681A
Authority: US
Inventors: Oscar E Rosaen
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-06-26
Filing date: 1967-06-26
Publication date: 1969-07-22
Anticipated expiration: 1986-07-22

Description

July 22, 1969 o. E. RosAEN 3,456,593

VARIABLE CAPACITY MECHANISM FOR FLUID PUMPS AND MOTORS Filed June 25, 1967 4 Sheets-Sheet l July 22, 1969 o. E. RosAEN 3,456,593

VARIABLE CAPACITY MECHANISM FOR FLUID PUMPS AND MOTORS Filed June 26, 1967 4 Sheets-Sheet 2 July 22, 1969 o. E. RosAEN i 3,456,593

VARIABLE GAACITY MECHANISM FOR FLUID PUMPS AND MOTORS Filed June 26, 1967 4 Sheets-Sheet i'.

BIZ

Zl 284 y INVHNTOR.

OSCA R E. ROSA EN ATTORNEYS July 22 1959 o. E. ROSAEN 3,456,593

VARIABLE CAPACITY MECHANISM FOR FLUID PUMPSv AND MOTORS Filed June 26, 1967 4 Sheets-Sheet 4 INVENTOR.

FIG- Il OSCAR EROSAEN BY #www www ATTO RN US United States Patent O VARIABLE CAPACITY MECHANISM FOR FLUID PUMPS AND MOTORS Oscar E. Rosaen, Grosse Pointe Shores, Mich. (1776 E. Nine Mile Road, Hazel Park, Mich. 48030) Filed June 26, 1967, Ser. No. 648,681

Int. Cl. F04c 15/04, 3/00 U.S. Cl. 103--120 12 Claims ABSTRACT OF THE DISCLOSURE A variable capacity mechanism for expansible chamber fluid pumps and motors of the rotary vane type in which the cam means which guide the vanes for extension and retraction in the pumping chamber is divided into two members having substantially semi-circular surfaces, one members being fixed with its cam surface at a substantially constant radius from the rotor, and the other member having a similar cam surface radius and being movable with respect to the rotor, the ends of the cam members having sliding tongue and groove engagement and shaped to be substantially tangent to arcs concentric with the cam for smooth transition of the vanes from the iixed to the movable member and vice-versa, and the movable member being cam actuated responsively to pump delivery or motor working pressure toward and away from said rotor, with means for pressure balancing the rotor, the movable cam member, and the individual vanes, with the cam surface contours and the pressure-balancing being such as will provide a smooth surge-free transitionas the vanes move between pressure and suction areas of the pump or motor chamber.

BACKGROUND OF THE INVENTION Field of the invention The invention relates to expansible chamber, variable capacity, rotary vane pumps and motors, the pumps having delivery pressure responsive means adjustable to position the vane-guiding cam for maintaining or varying pump delivery volume according to downstream requirement with predetermined substantially constant pressure, and the motors having similarly functioning means for load-compensation depending upon variable working pressure.

Description of the prior art Patents which indicate means for varying the capacity of a pump or motor of this general type by adjusting a portion of the vane-guiding cam member are the following: U.S. Patent Nos. 1,697,041; 2,031,749; 2,170,786; 2,222,144; 2,458,023; 1,693,540; Swiss Patent No. 101,021; German Patent Nos. 415,472 and 606,178; and Belgian Patent No. 502,418. Additionally, applioants issued Patent No. 3,272,139 shows a specialized type of variable capacity pump in which a movable cam portion is connected with a fixed cam portion by means of hinged ramp elements, and is adjusted responsively to pump delivery pressure. Problems relating to the above patents include not merely the complexity of construction, but the difficulty in obtaining movable cam adjustment, relatively slower response times, the effects of surge-producing transitional pressures, and presence of other unbalanced forces which will adversely aifect the operation of the pump or motor, all of which are corrected by the present variable capacity mechanism.

SUMMARY OF THE INVENTION In the present pump or motor, the fixed and movable cam ring members have cam surfaces disposed on a radius which is larger than the rotor radius, with the movable cam member adjustable between a position where its `radius is substantially concentric to and spaced from the rotor to a position at which the mid-section of the movable cam member is closely adjacent to the rotor, so that fluid moves from the inlet disposed on one side of said mid-section around to the outlet disposed on the other side of said mid-section, with the inlet and outlet respectively connected to diametrically opposite portions of the pump or motor chamber to substantially balance the rotor against unequal forces, and with the individual vanes substantially balanced at all times as they move between differing pressure areas of the chamber. In the case of a pump, there are special restricted orifice pressure ports to the inner ends of the vanes when in transition periods, the orices admitting pressure proportionately as the same pressure is permitted to escape through passages formed between the vane slots and beveled edges of the vanes on the leading sides thereof. Adjustment of the movable cam member is accomplished through the means of a sliding cam actuator moved in response to pump delivery or motor working pressure as opposed by a spring or the like. Means are provided for balancing the movable cam member against unequal pressure forces acting thereon, so that it can be readily adjusted by the aforesaid actuator. The midsection of the movable cam member, in the chamber area intermediate the inlet and outlet, is contoured such that when it is adjusted to an optimum or normal operational position, the cam arc is substantially concentric with the rotor periphery, producing improved surge-free operation.

DESCRIPTION OF THE DRAWINGS A more complete understanding of the invention may be had by reference to the accompanying drawings illustrating a preferred embodiment of the invention in which like reference characters refer to like parts throughout the several views, and in which:

FIG. 1 is a longitudinal cross-sectional View through a pump of the type described embodying the present invention;

FIG. 2 is a lateral cross-sectional View of the pump taken substantially on the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary lateral cross-sectional view taken substantially on the line 3 3 of FIG, l:

FIG. 4 is a perspective view of the cam members of the pump;

FIG. 5 is a perspective view of a preferred vane element for use in the present pump;

FIG. 6 is a lateral cross-sectional view of a fluid motor of the type described embodying the present invention;

FIG. 7 is a longitudinal cross-sectional View of the motor taken substantially on the line 7-7 of FIG. 6;

FIG. 8 is a cross-sectional view taken substantially on the line 8-8 of FIG. 6 but showing only the motor end Cap;

FIG. 9 is a perspective view of the cam members of the motor;

FIG. 10 is a perspective view of a vane element used in the motor of FIGS. 1-9; and

FIG. 11 is an enlarged fragmentary view of the rotor and cam used in the present invention to show contour details.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1-5 illustrate the present invention as embodied in a pump comprising a housing structure 10 having a pumping chamber 12 closed -by an end cap structure 14. A rotor 16 is carried in the pumping chamber 12 and splined to a shaft 17 supported by bearings 18 and 20 respectively carried in

coaxial bores

22 and 24 provided through the housing 10 and end cap structure 14. The

open end of the bore 24 in the end cap 14 is closed by` a plate 26 secured thereto by any means such as screws 28.

The periphery of the rotor 16 has a plurality of angularly spaced transverse slots 30` as shown in FIG. 2 in which are radially slidably carried a plurality of vane elements 32, with the inner ends of the vanes 32 being subjected to fluid pressures introduced into transverse bores 34 provided at the inner ends of the slots 30. A vane 32 is shown in FIG. to have an outer beveled end 36 and beveled edges 38 on the leading side thereof (i.e. facing the direction in which the vanes are moving as the rotor rotates as indicated by the directional arrow in FIG. 2).

A iixed cam member 40 is secured in the pumping chamber 12 and encircles approximately one-half of the rotor 16. The cam member 40 has an inner cam surface 42 which is concentric with the rotor outer periphery and radially outwardly spaced therefrom. A movable cam member 44 is disposed in the pumping chamber 12 and has a portion 46 extending oppositely yfrom the ixed cam member 40 and supported for sliding movement in ahn aperture 48 in the housing structure 10. The movable cam member 44 has an inner cam surface 50 formed on a radius substantially similar to the iixed cam member inner surface 42, except for a media portion to be described, and is adapted for adjustment toward and away from the rotor 16 to move the medial portion of the inner cam surface 50 between a zero or minimum expansion position (shown in FIG. 2), wherein the cam surface 50 is substantially concentric to and spaced from the periphery of the rotor 16 and fluid delivery is zero or minimum, to a maximum delivery position, indicated in FIG. 11, where the medial portion of the inner cam surface 50 is closely adjacent the rotor periphery, the cam surface 50 thereby forming adjacent slopes relative to the rotor periphery to provide adjacent contracting and expanding volumes between successive vanes in the pumping chamber 12 and to guide the vanes 32 for retraction aiid extension into and out of the slots 30, fluid delivery being at a maximum.

The ends of the

cam members

40 and 44 have slidable tongue and groove engagement as seen in FIG. 4, and the ends of the

cam surfaces

42 and 50 are flattened as at 51 to be substantially tangent to arcs concentric with the rotor 16, and parallel to the direction of cam member 44 adjustment, so that the vanes 32 will ride smoothly from one cam surface to the other as the rotor rotates, regardless of the adjusted position of the movable cam member 44.

The housing 10y and end cap 14 are arranged to provide an inlet recess 52 adjacent that portion of the movable cam member 44 on one side of its medial portion, and an outlet recess 54 adjacent the other portion of the movable cam member 44 on the other side of its medial portion. The inlet and

outlet recesses

52 and 54 are connected through respective inlet and

outlet ports

56 and 58 provided in the housing 10 with a source of fluid (not shown) and a tluid pressure user (not shown) respectively. Thus, when the movable cam member 44 has been adjusted toward the rotor 16, uid will be drawn into the inlet recess 52, carried around the periphery of the rotor 16, to rotate same in a counterclockwise direction as seen in FIG. 2, and discharged through the outlet recess 54, the delivery volume being a function of the proximity of the movable cam member 44 to the rotor 16.

The xed cam member 40 is provided with an outer peripheral groove 60 extending `from the end adjacent and open to the inlet recess 52 to a point 62 closely adjacent and closed off from the outlet recess 54. A gap 64 connects the groove 60 with the pumping chamber 12 at a location adjacent the rotor 16 substantially diametrically opposite the portion of the rotor which is exposed to the inlet recess 52. Pump delivery pressure is introduced through a passage 66 connecting the outlet recess 54 with an annular space 68 adjacent the shaft 17 of the rotor 16, the opposite sides thereof being openly communicated through bores 70` extending through the rotor 16, and the pressure is connected by means of a passage 73 bored in the housing 10 radially outwardly to a small side recess 72 in the iixed cam member 40, the recess 72 being open to the pumping chamber 12 adjacent the rotor 16 at a location substantiallyl diametrically opposite to the chamber portion adjacent the outlet recess 54. Admission of inlet and outlet pressures to these diametrically opposite portions of the rotor tend to balance the rotor against fluid pressure forces which would otherwise exert binding and Wear-producing stresses on the rotor 16 and its shaft 17.

It will be seen that as the rotor 16 rotates, the outer ends of the vanes 32 will move between areas of different pressures. These pressures need to be balanced at the inner vane ends with substantially similar pressures to prevent the vanes from being 4forced against the cam surfaces 42/and 50 With'too great a force, or from being retracted into their slots which would eliminate pumping. Therefore, arcuate recesses 74 and 76 respectively are provided in the housing 10` and cap 14 adjacent the pumping chamber 12 along an arc registering with the bores 34 at the inner ends of the vane slots 30, and in that area where the outer ends of the vanes 32 would be subjected directly to pump discharge pressure. The recesses 74 and 76 communicate with pump delivery pressure by means of the aforesaid passage 66 extending toward the hub of the rotor 16. Substantially diametrically opposite, a second set of arcuate recesses, namely recess 7'8 in the housing and a similar recess (not shown) in the end cap are provided adjacent the pumping chamber 12 on an arc registering with the bores 34 in that area where the outer ends of the vanes 32 are subjected to pressure from the recess 72 previously described. The recess 78 and the end cap recess (not shown) communicate with delivery pressure from the passage 73 extending between annular space 68 and the recess 72.

Other arcuate recesses 82 and 84 are provided respectively in the housing 10 and cap 14 adjacent the pumping chamber 12 on an arc registering with the bores 34 as the vanes move through the area directly adjacent the inlet recess 52. The recesses 82 and 84 are connected by means of a passage 86 with the inlet recess 52.

The aforesaid recesses introduce inlet and outlet pressures to the inner ends of the vanes 32 to provide proper end-to-end balancing thereof as they move.

Passages 88, all substantially the same, extend outwardly from the annular space 68 at the hub of the rotor and are connected through restricted orifices 90 with the pumping chamber 12 on an arcuate line registering with the bores 34 at the inner ends of the vane slots 30. A restricted pressure introduced at these points enables the vanes to move between areas of different pressure (that is, from an inlet pressure area to an outlet pressure area or vice-versa) without any sudden jump in balancing pressures which might tend to damage the vanes, cause noise, and produce undesirable surges of pressure. The orifice 90 at the location diametrically opposite the inlet recess 52 and designated by the letter A in FIGS. 2 and 3 is required to hold the vanes outwardly in an area where they might otherwise tend to part from contact with the cam surface. Also, small grooves 92 are provided at the leading ends of the

arcuate recesses

74 and 78, and at the orice 90 at location A. These grooves 92 serve the purpose of augmenting a smooth, surge-free transition from one balancing pressure to another. The vanes 32, as shown in FIG. 5, have the beveled edges 38 which are constructed to provide communication between the inner and the outer ends of the vanes 32 and are of a total cross-sectional area substantially equal to the cross-sectional area of each of the orifices 90. Thus, the pressure admitted through the lorifices 90 will be permitted to escape with controlled ow.

The housing 10 has a side recess 94 closed by a cover plate 96 secured by any means such as screws 98. An

actuator member 100 is slidably supported in the recess 94 on a central tube 102 extending from a fluid fitting 104 as shown in FIG. 2. The tube -2 is hollow for the admission -of pump delivery pressure which is conducted to the fitting 104 through a conduit (not shown) or the like connected with the outlet recess 54. Pressure admitted throguh the tube to the interior of the actuator 100 tends to move the actuator in the direction of the arrow in FIG. 2, and is opposed by a spring 106 compressed between the inner end of the actuator 100 and the recess of an adjustable fitting 108 which can be adjusted to vary spring'- compression and thus determine the pressure change required to move the actuator member 100.

The outer end surface 110 of the movable cam member portion 46 is sloped as shown in FIG. 2 at about a ten degree angle from the normal to direction of movement, and abuts a similarly sloped surface 112 of the actuator member 100, so that as the actuator member 100 is moved laterally back and forth dependent on variations in pressure admitted to its interior, the movable cam member will be cammed toward or away from the rotor 16. Thus, when the downstream fluid demand of the pump is decreased, for example by closing of a downstream valve, the delivery pressure will tend to increase, moving the actuator 100 against the force of the spring 106, and the fluid pressure acting on the interior vane-guiding cam surface 50 of the movable cam member 44 will cause the movable cam member to move away from the rotor 16 toward 4or to the position shown in the drawings to thereby decrease fluid delivery from the pump. As the requirements for uid pressure are increased, such as by opening a downstream valve, the pressure within the actuator 100 will correspondingly decrease, and the spring 106 will move the actuator to thereby cam the movable cam member 44 radially toward the rotor 16, to increase pump fluid delivery.

It will be seen that the movable cam member portion 46 is subjected on one side to the delivery pressure of the pump, and therefore a passage 1'14 through the cam member portion 46 admits pressure fluid to a recess 116 on the other side of the cam member portion 46 through a restricted orice 118. The size of the recess 116 is such as will substantially balance the movable cam member portion 46 from side-to-side to prevent a tendency toward binding thereof.

A spring-loaded vane member 120 is provided in a slot 121 on the pressure side of the movable cam member portion 46 to engage the side of the aperture 48 and minimize leakage of pressure therethrough. The inner end of the slot 121 is recessed for the spring and connected with delivery pressure through a passage 122 extending between the pressure passage 114 and the face of the movable cam member sloped surface 110. The pressure to this surface 110 tends to keep it and the actuator sloped surface 112 from sticking, so that response to pressure moving the actuator member 100 will be instantaneous. Fluid leakage into the side recess 94 will be returned to the inlet recess 52 through a passage 124 in a slide plate 126 secured to the side of the aperture 48 as seen in FIG. 2.

FIGS. 6-l0 illustrate the present invention as embodied in a load compensating, expansible chamber uid motor comprising a housing structure 210 having a working chamber 212 closed by an end cap structure 214. A rotor 216 is carried in the working chamber 212 and keyed to a shaft 217 supported by

roller bearings

218 and 220 along with bushings 218A and 220A, respectively carried in coaxial bores 222 and 224 provided through the housing structure 210 and the end cap structure 214. The open end of the bore 224 in the end cap 214 is closed by a plate 226 secured thereto by any means such as screws 228.

The periphery of the rotor 216 has a plurality of angularly spaced slots 230 as shown in FIG. 6, 'in which are radially slidably carried a plurality of vanes 232,

with the inner ends of the vanes 232 being subjected to fluid pressure introduced into transverse bores 234 provided at the inner ends of the slots 230.

A fixed cam member 240` is secured in the working chamber 212 and encircles approximately one-half of the rotor 216, The cam member 240 has an inner cam surface 242 which is concentric with the rotor outer periphery and radially outwardly spaced therefrom. A movable cam member 244 is disposed in the working chamber 212 and has a portion 246 extending oppositely from the fixed cam member 240 and supported for sliding movement in an aperture 248 in the housing structure 210. The movable cam member 244 has an inner cam surface 250 formed on a radius substantially similar to the xed cam member inner surface 242, except for a medial portion to be described, and is adapted for adjustment toward and away from the rotor 216 to move the medial portion of the inner cam portion 250 between a zero or minimum expansion position (shown in FIG. 6), wherein the cam surface 250 is substantially concentric to and spaced from the periphery of the rotor 216, and the motor is working at minimum load, to a maximum expansion position, indicated in FIG. l1, where the medial portion of the inner cam surface 250 is closely adjacent the rotor periphery, the came surface 250 thereby forming adjacent slopes relative to the rotor periphery to provide adjacent contracting and expanding volumes between successive vanes in the working chamber 212 and to guide the vanes 232 for retraction and extension into and out of the slots 230, the motor working at maximum load.

The ends of the

cam members

240 and 244 have slidable tongue and groove engagement as seen in the exploded view of FIG. 9, and the ends of the carne surfaces 242 and 250 are iattened as at 251 to be substantially tangent to arcs concentric with the rotor 216, and parallel to the direction of cam member 244 adjustment, so that the vanes 232 will ri-de smoothly from one cam surface to the other as the rotor 215 rotates, regardless of the adjusted position of the movable cam member 244.

The housing 210 and end cap 214 are arranged to provide

recesses

252 and 254 respectively adjacent portions of the movable cam member 244 on the two sides of its medial portion. These

recesses

252 and 254 are connected through respective ports 256 and 258 provided in the housing 210 with a source of fluid under pressure (not shown) and a fluid reservoir (not shown). The motor is constructed symmetrically so that either of the ports 254 or 256 may serve as inlet or outlet ports, for operation of the rotor 216 in either direction.

For the purpose of the following discussion, the motor will be described by assuming that fluid under pressure is supplied to the port 256, and the port 258 is connected with a reservoir. Thus the recess 252 will be described as the inlet recess and the recess 254 will be described as the outlet recess. Thus, with the movable cam member 244 adjusted toward the rotor 215, fluid from the inlet recess 252 will move the vanes 232, and consequently rotate the rotor 216 in a counterclockwise direction as seen in FIG. 6, the iiuid moving around the periphery of the rotor 216 to be discharged through the outlet recess 254, the volume of working fluid performing useful work being a function of the proximity of the movable cam member 244 to the rotor 216.

The fixed cam member 240 is provided with an arcuate groove 260 on one side extending from the end adjacent and open to the inlet recess 252 to a recess 262 open to the working chamber 212 at a location adjacent the rotor 216 substantially diametrically opposite the portion of the rotor which is exposed to the inlet recess 252. A second arcuate groove 264 extends from the end of the fixed cam member 240 adjacent and open to the end of the outlet recess 254 to a recess 266 opening to the working chamber 212 at a location adjacent the rotor 216 substantially diametrically opposite the portion of the rotor which is exposed to the outlet recess 254. Admission of the inlet and outlet pressure to these diametrically opposite portions of the rotor tends to balance the rotor against uid pressure forces which would otherwise exert binding and wear producing stresses on the rotor 216 and its Shaft 217.

It will be seen that as the rotor 216 rotates, the outer ends of the vanes 232 will move between areas of different pressures. These pressures need to be balanced at the inner vane ends with substantially similar pressures to prevent the vanes from scoring the cam surfaces or from being retracted into their slots. Therefore, arcuate recesses 274 and 276 are provided in the housing 210 adjacent the working chamber 212 along arcs registering with the bores 234 at the inner ends of vane slots 230- and in those areas where the outer ends of the vanes 232 are subjected directly respectively to inlet and outlet pressures. The recesses 274 and 276 communicate respectively with the

recesses

252 and 254 by means of passages 278 and 280 respectively provided in the housing 210.

Other

arcuate recesses

282, 284, 286, and 288 are provided in the housing 210 adjacent the working chamber 212 on arcs registering with bores 234 as the vanes move through areas in which their ends are not subjected directly to pressures connected with either the inlet or the outlet.

Radial passages

282A, 284A, 286A and 288A connect the respective recesses 282, 284, 286, and 2818 with an annular space 290` provided in the housing at the hub of the rotor 216 around the shaft 217. This annular space 290 is provided with uid, under pressure corresponding to the pressure of the working fluid at the inlet to the motor, through a passage 292 terminating in a port 294 adapted for connection with any suitable conduit or the like. Introduction of pressure fluid beneath the vanes in these areas will maintain the vanes in contact with the cam ring members. Additionally, each 'vane is at all time urged outwardly by lightweight springs 296 which are seated in holes extending radially inwardly from the bores 234. These bores are axially aligned with the slots 230, and the springs 296 engage in recesses 298 provided in the bases of the vanes 232 as shown in FIG. 10. This will insure that on starting the motor, and at any time that pressure may be interrupted, the vanes will remain in contact with the cam members. The vanes 232 are balanced end-to-end by the provision of passages 300 extending from the recess 298 outwardly to the ends of the vanes which are arcuately grooved as at 302 so that only the extreme leading and trailing edges of the outer ends of the vanes are contacting the cam surfaces and the outer ends of the vanes are therefore subjected to the pressures communicated thereto through the passages 300.

The housing 210 has a centrally positioned side recess 304 closed with a cover plate 306 secured by screws 308 or the like. An actuator member 310 is slidably supported in the recess 304 on a tube 312 extending inwardly from a uid fitting 314 secured to the housing 210 and the cover 306 by any means such as screws 315 as shown in FIG. 6. The tube 312 is hollow for the admission of motor working pressure which is conducted to the fitting 314 through a conduit (not shown) or the like connected 'with the source of working fluid. Pressure admitted through the tube 312 to the interior of the actuator 310 tends to move the actuator in the direction of the arrow shown on the actuator member 310 in FIG. 6, and is opposed by a spring 316 compressed between an abutment plate 317 secured to the inner end of the actuator 310 by a screw 317A or the like and the recess of a closure cap 318 secured to the housing and cover plate 306 by any means such as screws 319.

The outer end surface 320 of the movable cam member portion 246 is sloped as shown in FIG. 6 at about a ten degree angle from the normal to direction of movement, and abuts a similarly sloped surface 322 of the actuator member 310, so that as the actuator member 310 is moved laterally back and forth dependent on variations in pressure admitted to its interior, the movable cam member `will be cammed toward or away from the rotor 216. Thus, when the load on the motor is increased tending to slow down the motor, the working pressure will tend to increase, moving the actuator 310 against the force of the spring 316 to thereby cam the member 244 radially toward the rotor, effecting an increase in the working force produced by the motor. Conversely, as the load on the motor decreases tending to permit the motor to speed up, the fluid working pressure will tend to decrease, and the pressure within the actuator 310 will correspondingly decrease so that the spring 316 Will move the actuator in the opposite direction, and the fluid pressure acting on the interior 'vane-guiding cam surface 250 on the movable cam member 244 Will cause the movable cam member to move away from the rotor 216 toward or to the position shown in FIG. 6, effecting a decrease in the working force produced by the motor. The movable cam member 244 will 'be prevented from moving to a fully unloaded position by having the abutment plate 317 adjusted to contact the cam member 244 just prior to the time it would become completely unloaded, to thereby keep some load so that the rotor will not overspeed.

It will be seen that the movable cam member 244 is subjected to pressures tending to force its end radially outward against the housing, and therefore the cam member portion 246 needs to be balanced against these pressures. As seen in FIGS. 6 and 9, recesses 324 and 326 are provided on the sides of the movable cam member 244 and are interconnected by a passage 328. When the recess 252 is connected with working pressure, it is admitted to the passage 328- through a check valve 330. When the recess 254 is connected with working pressure, the pressure is admitted to the passage 328 through a similar check valve 322 on the other side as shown in FIG. 6. This pressure admitted to both sides of the movable cam member 244 prevents binding thereof as it moves axially toward and away from the rotor 216. Further, one side or the other of the extending portion 246 of movable cam member 244 is subjected to working pressure from the recess 252 or 254 (depending on which way the motor is working), and to compensate for this unbalancing, a pair of

passages

334 and 336 extend from spaces communicating respectively with the

recesses

252 and 254 to opposite sides of the extending portion 246 to admit the working pressure to

respective recess

338 or 340 provided on the sides of the aperture 248 in the housing 210.

FIG. 1l is a greatly enlarged view of the previously mentioned medial portion of the movable cam member 44 (or 244) intermediate the inlet and outlet of the pump or motor, and a corresponding portion of the rotor 116 (or 216), illustrating the cam surface 50 (or 250) in a normal operating position (solid-line A) about half-way between the minimum expansion position (dash-line B) and the maximum expansion position (dash-line C), the enlargement illustrating an important feature of the invention. In the solid-line position shown, the actual contour of the medial portion between points X and Y is on a radius concentric with the peripheral surface of the rotor 16 (or 216), so that in normal operation there will be no sudden transition between contraction and expansion of the fluid chamber which I have found will otherwise tend to produce disruptive surges in fluid pressures. The remainder of the cam surface 50 (or 250) beyond the points X and Y is radiused similarly to the radius of the fixed cam member 40 (or 240) so that the ends of the cams always meet. The dot-dash lines D, E and F indicated in FIG. 1l illustrate how the medial portion between points X and Y would appear respectively at the normal, minimum expansion, and maximum expansion positions if the cam surface 50 (or 250) medial portion were radiused like the rest of the surface beyond the points X and Y. Thus it is apparent that this slight deviation from constant radius in the medial portion will have little effect at either the minimum or maximum positions, yet in or near normal operating position the surge-free function will be effective.

Although I have described and shown only one modification of my invention, it Will be apparent to one skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or the scope of the appended claims.

What is claimed is:

1. A variable capacity mechanism for expansible chamber fluid pumps and motors comprising:

(a) a housing having a fluid chamber,

(b) a rotor in said chamber and angularly spaced radially slidable vanes carried by said rotor,

(c) cam means contacting and guiding said vanes for sliding operation as said rotor turns, said cam means having:

(l) a fixed cam member having an inner surface substantially concentric to and outwardly spaced from approximately one-half of said rotor,

(2) a movable cam member having an inner surface radius substantially similar to the fixed member inner surface radius and movable between a minimum expansion position substantially concentric to and outwardly spaced from the other approximately one-half of said rotor and a maximum expansion position in which the mid-section of the movable cam member inner surface is disposed closely adjacent the rotor,

(d) an inlet to said chamber adjacent said other onehalf of said rotor at one side of said midsection of the movable cam member,

(e) an outlet connected to said chamber adjacent said other one-half of said rotor at the other side of said midsection of the movable cam member, and

(f) the separation between said inlet and outlet being greater than the spacing between any two successive vanes.

2. The mechanism as dened in claim 1 and in which the ends of said cam members have slidable tongue and groove engagement and in which the inner surfaces of the cam member ends are approximately tangent to arcs concentric to the rotor and extend parallel with the direction of movement of said movable cam member.

3. The mechanism as defined in claim 1 and in which:

(a) said housing has an aperture extending radially outward from said fluid chamber on the side opposite said fixed cam member,

(b) said movable cam member has a portion carried by and radially slidable in said aperture, and

(c) said housing carries means operatively connected with the movable cam member and adjusting same radially toward and away from said rotor responsive to fluid pressure.

4. The mechanism as defined in claim 3 and in which said last-mentioned means comprises an actuator having a camming surface slidably coacting with a cammed surface on said movable cam member, and pressure responsive means operable to adjust said actuator relative to said movable cam member for camming same toward and /away from said rotor.

5. The mechanism as defined in claim 3 and in which:

(a) said movable cam member slidably carried portion has a cammed surface on the side opposite the inner surface which contacts said vanes and sloped at an angle to a plane extending normal to the movable cam direction of movement,

(b) an actuator having a camming surface slidably coacting with said movable cam member cammed surface, and

(c) pressure responsive means operable to adjust said actuator relative to said movable cam member for camming .same toward and away from said rotor.

6. The mechanism as defined in claim 3 and in which:

(a) said movable cam member slidably carried portion has a cammed surface on the side opposite the inner surface which contacts said vanes and sloped at an angle of about ten degrees to a plane extending normal to the movable cam direction of movement,

(b) an actuator having a camming surface slidably coacting and complementary with said movable cam member cammed surface, and

(c) pressure responsive means operable to adjust said actuator relative to said movable cam member for camming same toward and away from said rotor.

7. The mechanism as defined in claim 5 when used in a pump and in which:

(a) said actuator has means resiliently urging same toward a direction camming the movable cam member toward said rotor for increasing pump delivery,

(b) means opposing said resilient urging means with a pressure proportional to tendencies of said pump to increase delivery pressure, and

(c) said movable cam portion is urged radially outwardly from said rotor by pump pressure directed against said inner cam surface.

8. The mechanism as defined in claim 5 when used in a motor and in which:

(a) said actuator has means resiliently urging sarne toward a direction permitting the movable cam member to move away from said rotor for decreasing the motor working force,

(b) means opposing said resilient urging means with a pressure proportional to motor inlet pressure as determined by the load on said motor, and

(c) said movable cam portion is urged radially outwardly from said rotor by working pressure directed against said inner cam surface.

9. A variable capacity mechanism for expansible chamber fluid pumps and motors comprising:

(a) a housing having a fluid chamber,

(2) a movable cam member having an inner surface radius substantially similar to the fixed member inner surface radius and movable between a minimum expansion position substantially concentric to and outwardly spaced from the other approximately one-half of said rotor and a maximum expansion position in which the midsection of the movable cam member inner surface is disposed closely adjacent the rotor,

(f) means connecting said inlet and outlet with said fluid chamber diametrically opposite respectively said inlet and outlet to tend to balance pressures radially directed on said rotor.

10. A variable capacity mechanism for expansible chamber fluid pumps and motors comprising:

(a) a housing having a fluid chamber,

(f) said rotor having angularly spaced slots in its periphery carrying said vanes for radial extension and retraction thereof as guided by said cam means,

(g) means connecting the inner ends of said vanes to inlet and outlet pressures varying to effect balancing of said vanes as they move into areas of diierent pressures,

(h) said vanes having means restrictingly connecting the inner ends to the outer leading side ends, and

(i) means connecting the inner vane ends to pressure restricted proportionately with the aforesaid restrictingly connecting means as said vanes move from outlet-connected to inlet-connected areas of said chamber whereby to provide gradual changes in balancing pressures.

11. The mechanism as dened in claim 1 and including means pressure balancing said movable cam member normally with respect to the direction of cam member movement and to the axis of said rotor.

12. A variable capacity mechanism for expansible chamber uid pumps and motors comprising:

(2) a movable cam member having an inner surface radius substantially similar to the xed member inner surface radius and movable between a minimum expansion position substantially concentric to and outwardly spaced from the other approximately one-half of said rotor and a maximum expansion position in which the midsection of the movable cam member inner surface is disposed closely adjacent the rotor,

(f) said movable cam member inner surface having a medial portion extending between the inlet and outlet and radiused to be concentric with the rotor periphery only when the movable cam member is positioned about midway between its minimum and maximum expansion positions, the remainder of said movable cam member inner surface being substantially concentric with the rotor periphery only when the movable cam member is positioned at its minimum expansion position.

References Cited UNITED STATES PATENTS 1,693,540 11/1928 c Balsiger. 2,170,786 8/ 1939 McElroy et al. 2,238,786 4/ 1941 Warman. 3,117,528 l/1964 Rosaen. 3,272,139 9/1966 Rosaen.

FOREIGN PATENTS 502,418 4/ 1951 Belgium. 415,472 6/ 1925 Germany.

DONLEY J. STOCKING, Primary Examiner WILBUR I. GOODLIN, Assistant Examiner U.S. C1. X.R.

(El/69) UNITED STATES PATENT oFFICE CERTIFICATE OF CORRECTION Parent No. Y 3,456,593 Dated July-22, '1969 Inventor(s) Oscar E. Rosaen It is certified tha and that said Letters Pa t error appears in the aboveidentified patent tent are hereby corrected as shown below:

IN TI-IE SPECIFICATIONS Column 6, line 25, change "came" to cam.

Column 6, line 33, change "came" to "Cal--o SIGNED AND SEALED m1281970 6m) Attest:

Edward M. Fletcher, Ir.

WILLIAM E. Sm, IR. P tents Atting Officer Gomssioner of a