US3549281A - Variable volume vane type pump - Google Patents

Description

Dec. 22, 1970 R. R. SCHINK EI'AI. 3,549,281

VARIABLE VOLUME VANE TYPE PUMP- Filed Dec. 5; 1968 3 Sheets-Sheet 1 Dec. 22, 1970 1, HHQ EIAL 3,549,281

VARIABLE VOLUME VANE TYPE PUMP Filed Dec. 5, 1968 3 Sheets-Sheet 2,

4 f- 160 15 945 i il-iii Dec. 22; 1970 Filed Dec. .5, 1968 R. R. SCHINK VARIABLE VOLUME VANE TYPE PUMP 5 Sheets-Sh eet 3 I I 215 11 217 ,5 Z19 United States Patent 3,549,281 VARIABLE VOLUME VANE TYPE PUMP Richard R. Schink and Ernst F. Klessig, Racine, Wi s.,

assiguors to Rex Chainbelt Inc., a corporation of WIS- cousin Filed Dec. 3, 1968, Ser. No. 780,691 Int. Cl. F04c 15/04 US. Cl. 418-31 11 Claims ABSTRACT OF THE DISCLOSURE A variable volume vane type pump having a slotted rotor with vanes movably carried thereon and a control ring surrounding the rotor for controlling the position of the vanes with a pressure compensating control for the ring to establish the maximum pressure setting of the pump and with means for stabilizing the pressure compensating control including restricted passage means which tends to be self-cleaning connecting the outlet of the pump to a control piston which controls positioning of the ring. Additionally, a two stage control is disclosed including a settable pilot stage and a first stage including a control valve with a high rate spring to further stabilize the control.

CROSS REFERENCE TO RELATED APPLICATION This application discloses a vane type pump and pressure control wherein the pump is constructed similarly to that shown in an application of Messrs. Dadian, Gehrung, and Grifiiths entitled A Fluid Translating Device, Ser. No. 772,173, filed Oct. 31, 1968 and the disclosure thereof is incorporated herein by reference.

BACKGROUND OF THE INVENTION This invention pertains to variable volume vane type pumps and pressure compensation controls therefor.

Pressure compensation controls for variable volume vane type pumps are known. However, there have been problems in stabilizing the control during pressure compensation. This problem is overcome by the structure disclosed herein wherein restricted passage means connect the pump output to the control piston for the vane control ring at all times. Additionally, the two stage conrol provides for remote pressure setting and stable control for small volume pumps with minimum loss of fluid.

SUMMARY An object of this invention is to provide a new and improved variable volume vane type pump and control therefor wherein the pressure compensation control is stabilized with resultant reduction in oscillations of the control ring for the pump vanes.

Another object of the invention is to provide structure as defined in the preceding paragraph wherein the stabilization is provided by a restricted passage means connecting the pump output to a control piston for the control ring to have constant restricted communication therebetween.

Still another object of the invention is to provide a pressure compensation control for a Variable volume vane type pump wherein a control ring controls the position of vanes movably carried by a slotted rotor and with the ring being positioned by a control piston under the control of a servo valve, with the servo valve selectively controlling communication of the control piston with the pump output and a tank connection, dependent upon the pressure of the pumped fluid and the setting of the valve for controlling the pressure compensation range of the pump and with restricted passage means placing the pump output in constant limited communication with the control piston,

said restricted passage means being formed as at least a single flat on a land of the servo valve member whereby the land is not effective to completely block communication between the pump output and the control piston.

A further object of the invention is to provide a two stage pressure compensation control having the stabilizing feature provided by the restricted passage means and, further, functioning to provide a stable control for a pump and, particularly, a small volume pump to minimize the gain, i.e., to minimize the pressure and volume changes in the pump by having a manually or remotely settable second pilot stage for controlling the pressure at which the pump will begin to compensate and having a high rate spring acting on the valve spool of the pressure compensating control which tends to cut down oscillations of the valve spool in response to pressure changes.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a central plan section of the vane type pump and control associated therewith with parts of the servo valve broken away;

FIG. 2 is a view similar to FIG. 1 of the servo valve for pressure compensation control of the pump and shown in a shifted position;

FIG. 3 is an enlarged view of the valve spool of the valve in elevation;

FIG. 4 is a section taken generally along the line 44 in FIG. 3;

FIG. 5 is a fragmentary view similar to FIG. 1 of a second embodiment; and

FIG. 6 is an enlarged plan view of the valve spool shown in FIG. 5;

DESCRIPTION OF THE PREFERRED EMBODIMENTS The pump has a two-part casing including a first part 10 having a mounting base 11 and a cylindrical chamber 12 for receiving the pumping elements to be described. A second casing part 15 has a cylindrical section 16 which fits into the cylindrical chamber 12 to close off the chamber. The casing parts are sealed together by a seal 17 positioned therebetween and are held together by threaded attaching members, not shown.

The pumping elements include a rotor 20 having a series of outwardly movable vanes 22 about the perimeter thereof with the outward extent of the vane movement being controlled by a movable control ring 23 in the form of an annular member surrounding the rotor 20.

The rotor 20 is rotatably mounted by an integralshaft having sections 25 and 26 extending outwardly from opposite sides of the rotor to rotatably fit in bearings 27 and 28, respectively, received in concentric openings 29 and 30 in the casing parts 15 and 10. The opening 29 in casing part 15 does not extend to the outer face of the casing part; however, section 26 of the rotor shaft extends outwardly of the pump casing for a drive connection. A seal 31 is fitted in a recess 32 in the casing part 10 to surround and seal the rotor shaft section 26.

In order to form closed pumping spaces between adjacent vanes 22 and the movable ring 23, the sides of said spaces are closed off by a pair of pressure plates 40 and 41 positioned in the chamber 12 and at opposite sides of the rotor 20. Each of the pressure plates is of generally the same construction, with each pressure plate being generally disc-shaped and of composite construction, with the major section 42 thereof being formed of conventional material. The major section has a face section 43 bonded thereto, with the face section having a surface layer of bearing-type material, such as bronze, to have facial engagement with the sides of the rotor 20, the vanes 22 and the movable ring 23. The detailed construction of the pressure plates is particularly disclosed 3 in the copending application of Messrs. Dadian, Gehrung and Grifliths, referred to above. Each of the pressure plates has a pressure port and a vane balancing groove, the latter of which communicates with the inner end of the rotor slots to urge the vanes outwardly and provide partial pressure balancing for the vanes 22 during crossover.

Each of the pressure plates has a pair of suction ports with corresponding vane balancing grooves, with the latter supplying fluid to balance the vanes. As more fully disclosed in the application referred to, to have a pump of high efliciency and with reduced leakage, the pressure plates are urged toward the rotor 20 and movable ring 23 by pumping pressure. The necessary force is obtained by sealing-01f an area of the outer face of the pressure plate of a size which, when subjected to pump pressure slightly exceeds the forces generated by fluid under pressure between the vanes 22. The pressure balancing area for each pressure plate is of a kndney-shape and defined by a correpsondingly-shaped continuous groove receiving a seal structure 70.

The body part has suitable passages (not shown) connected to the pressure port and suction ports for receiving pumped fluid and supplying fluid to the pump, respectively.

A spacer ring 90 surrounds the control ring 23 and defines a minimum spacing between the pressure plates 40 and 41.

The movable control ring 23 is controlled in its positioning relative to the rotor 20 to control the output of the pump byhydrau lic means including a pair of opposed hydraulic pistons 91' and 91a enggaing the outer surface of the control ring 23 through openingsprovided in the spacer ring 90. The porting in the pressure plates 40 and 41 is arranged to have the force vector of the pumping forces act upwardly on the ring 23in a direction toward a thrust member (not shown). This structural relation results in a minimal amount of force derived from the pumping action acting along a line which is coincident with the axes of the pistons 91 and 91a.

The piston 91 is movable in a chamber 95 in the casing part and has an operative end 96 extending through an opening in the spacer ring 90 to engage the outer surface of the movable ring 23. The chamber 95 is closed 013? by a cover 98 secured to the casing part 10 and with a recess 99 providing a fluid chamber adjacent the end of the piston chamber 95. The piston 91 is subjected to the pressure existing at the pressure ports of the pressure plates by communicating passages 100, 101 and 102 formedin the second casing part which extend between the kidney-shaped pressure area at the back side of the pressure plate 41'and a passage 103 formed in the casing part 10 which communicates with the recess 99. Forces acting on the piston 91 will urge the movable ring 23 away from the eccentric full flow position toward a position in which the ring is concentric with the rotor to re duce the volume of the pump output and place the pump in a dead-head" operation with resultant saving of horsepower. I

The actual position of the movable ring is controlled by the hydraulic piston 91a acting in opposition to the piston 91. The piston 91a is movable in a chamber 105 formed in the casing part -10 and has a reduced end 106 engaging against the outer surface of the control ring 23. The cross-sectional area of the piston 91a is approximately twicethat of the piston 91. The piston 91a has an internal recess 110 opening to the rear thereof which receives a spring 111 urging the piston 91a toward the ring. The end of the piston chamber is closed off by the body 112 of a pressure compensating servo valve assembly fixed to the casing part 10.

All of the foregoing structure is disclosed in the abovementioned application of Messrs. Dadian, Gehrung and Griffiths and, as stated above, the disclosure thereof is incorporated herein by reference.

In the embodiment of FIGS. 14, the valve body 112 has a longitudinally-extending valve bore 115, with a connecting passage 116 leading to the chamber for the piston 9111. A passage 117 communicates with the bore to one side of the connecting passage 116 and communicates with the pump output through a series of connecting passages 118, 119, and 120 in the body parts 10 and 15. The passage 120 communicates with the kidney-shaped pressure area of the pressure plate 41 whereby fluid at outlet pressure is delivered to the bore 115.

" A tank passage communicates with the bore 115 at the side of the connecting passage 116 opposite the pressure passage 117.

A valve member is movable in the bore 115 and is urged toward the right, as viewed in FIG. 1, by an adjustable spring structure which sets the pressure at which the pump will begin to compensate. This structure includes a spring 131 engaging, at one end, a disc 132 engageable with the valve member 130. The other end of the spring engages a piston member 133 carrying an annular seal. The valve body 112 has an open-ended bore including a spring chamber to receive this structure. The spring chamber connects to a drain passage by a passage (not shown). An adjusting cap 135 threads to the interior of the valve body 112, as indicated at 136 to close the bore. The adjustment of the cap is maintained by a lock nut 137 which threads onto the cap 135. The cap 135 has an internally threaded opening to receive a. threaded end of the piston member 133, as indicated at 138. A threaded plug 140 threads into the interior of the cap. The three-piece construction for dead-head pressure adjustment permits setting the pump to a maximum pressure so that any subsequent pressure adjustment cannot accidentally exceed the maximum pressure without deliberately removing the plug 140 andturning the member 133. The maximum pressure setting is obtained by first having the plug 140 removed and the cap 135 is turned until it makes contact with a stop pin 141. While the pump is running in dead-head operation, the member 133 is turned until a desired pressure is obtained. A plug 140 is then inserted and locked against the member 133. This now allows all adjustments below maximum setting by turning cap 135 and locking it with the nut 137.

The right-hand end of the bore 115 is closed olf by a threaded cap threaded into the bore to define a chamber 146 which is subject to pump output pressure. This is accomplished by having an internal passage 150 in the valve member 130 having an opening 151 to the exterior of the valve member which, at all times, communicates with the inlet passage 117 connected to pump output. The opposite end of the internal passage 150 has an opening 152 into the chamber 146. With this construction, pump pressure is applied to a land 153 adjacent the right-hand end of the valve member which creates force in opposition to the adjustable spring 131.

A pair of lands and 161 are provided on the valve member 130 intermediate the ends thereof for controlling the communication to and from the connecting passage 116 leading to the control piston 91a. The land'160 controls communication between the inlet passage 117 and connecting passage 16, while the land 161 controls communication between the connecting passage 116 and the tank passage 125.

With the parts shown in the position of FIG. 1 the pump is in full flow condition with the control ring 23- at its maximum eccentric position. This condition, on starting, is caused by the force of the spring 111 associated with the control piston 91a and as pressure builds up in the pump the fluid pressure acts against the control pistons 91 and 91a and with the latter having a larger area the control piston 91a controls to maintain the full offset position of the control ring 23. In this condition, the valve member 130 is in its right-hand limit position, as viewed in the drawings, wherein the land 161 blocks communication between the connecting pas sage 116 and the tank passage 125, while the land 160 permits communication between the inlet passage 117 and the connecting passage 116.

When the pressure compensating range is reached, as determined by the setting of the adjustable spring mechanism including spring 131 of the servo valve, the pump pressure acting on the right-hand end of the valve member 130 moves the valve member toward the left, as viewed in FIG. 2 of the drawings, to move the land 161 from obstructing relation and permit fluid flow from the connecting passage 116 to the tank passage 125. As a result, the pressure acting on the control piston 91a decreases and the piston 91 gradually is effective to shift the control ring 23 toward a position of near concentricity with the rotor 20. This movement also places the land 160 in a position to restrict flow from inlet passage 117 to the connecting passage 116. As the pressure of the pump fluid decreases below the pressure compensating range, the spring 131 again takes over to cause fluid pressure on control piston 91a to shift the ring to the position shown in FIG. 1.

In order to stabilize the pump in the pressure compensating range by reducing the tendency for the control ring 23 to oscillate, restricted passage means are provided for subjecting the control piston 91a to pumped fluid. This restricted passage means, in the illustrated embodiment, is defined by a pair of flats 170 and 171 on the land 160 of the valve member 130 which render the land effectively discontinuous and permit constant restricted communication between the inlet passage 117 of the valve and the connecting passage 116 regardless of the position of the land 160 in the bore 115 of the valve. The flats 170 and 171, together with the valve bore 115, define a restricted orifice passage which connects the pump output to the control piston 91a. The total over-all area of the orifice provided by the flats 170 and 171 is sufficient to provide the stabilization for the control but is held to a minimum in order to limit fluid loss to the tank passage 125 during dead-head operation of the pump. There is no loss of oil through the restricted passage until the pump goes into compensation, since until such time the valve land 161 blocks communication to the tank passage 125. The restricted passage also has some limited effect in decreasing the recovery time of the control ring 23 in moving from a dead-head position to an eccentric pumping position in that additional fluid can flow to the control piston 91a because of the flats 170 and 171.

An important feature is the self-cleaning nature of the restriction provided by the flats 170 and 171. The orifice is small to provide the necessary control and limit loss of fluid. If a fixed member were used then the orifice size would require pre-filtering of the fluid. With the orifice defined by parts of the movable valve member, it tends to be self-cleaning because of the valve movement.

The preferred embodiment of the pressure compensating control is shown in FIGS. 5 and 6 in association with the same vane pump construction as shown in FIG. 1. This control includes a valve body 200 having spaced parallel bores 201 and 202 for each receiving valve components providing a two-stage control. The valve body 200 mounts a block 205 at one end which closes off the 'bores 201 and 202 and which has structure for manually setting the pressure at which the purnp will begin to compensate. The block 205 is interchangeable with other structures for setting the pilot stage of the two-stage control, with examples of such systems being an electrically-responsive system, such as shown in the Clark and Wirtz Pat. No. 3,411,531. The pressure can also be set remotely through a hydraulic system connected to the valve body 200.

The bore 201 has communication with a passage 206 which communicates with the pump outlet passage 118, a control passage 207, which connects with the control piston 91a, and a drain passage 208 leading to the bore 202.

A valve member 210 is movable in the bore 201 and has end lands 211 and 212 of substantial length with intermediate control lands 215 and 216. An internal passage 217 extends for a major part of the length of the valve member 210 and opens to one end of the valve member and communicates with a pair of transverse passages 218 and 219 whereby pump output fluid can be directed from one end of the bore 201 to the portion thereof between the valve lands 212 and 216.

The valve member 210 is urged toward the left as viewed in FIG. 5 by a high rate spring 220 positoned in a spring chamber 224 defined by an enlarged portion of the bore 201 and between a disc 221 engageable against an end of the valve member 210 and a threaded plug 222 threaded into the end of the valve body bore and sealing the bore by means of an O-ring 223.

The 'bore 202 threadably mounts a valve seat member 230 against which a poppet valve member 231 seats and which is urged into seated position by a spring 232 engaged between the poppet valve member and a disc 233. The pressure at which the poppet valve member 231 will open is set by the mechanism carried in the block 205, including the threaded pin 234 engageable with the disc 233 and carried by a threaded cap 235 which is threadably mounted in the block 205 and held in adjusted position by a lock nut 236 with a knob 237 facilitating rotation of the threaded cap 235. A plug 238 engages against the pin 234 to maintain it in position. This structure carried by the block 205 functions smilarly to that described in connection with the embodiment of FIGS. 1 and 2 to obtain a factory preset maximum pressure for the pump.

An end 240 of the bore 202 is closed by a plug 241 and comunicates with the spring chamber 224 by a passage 242. The valve seat member 230 has a passage 243 to subject the poppet valve member 231 to the pressure of fluid in the bore end 240. The land 212 of the valve member 210 has a pair of flats on the top and bottom thereof, one of which is shown at 250 in FIG. 6, which provides, with the wall of the bore 201 passages whereby fluid from valve passage outlet 219 can flow to the bore end 240. The land 216 of valve 210 has a pair of flats, one of which is shown at 251, which function similarly to the flats and 171 of the first embodiment to define restricted passage means placing the pump outlet in constant communication with the control piston passage 207, by communication through the valve passage 217.

With the pump operating at a pressure below that set for compensation by adjustment of the mechanism carried by block 205, the pressure acting on the poppet valve member 231 is not suflicient to open this valve of the pilot stage whereby there is no fluid flow.

When a pressure is reached to cause the pressure compensation control to be operative to control the position of the pump control ring, the poppet valve member 231 moves off its seat, as shown in FIG. 5, to permit flow therepast and to drain through a passage (not shown) leading from the bore 202. Greater pressure acting on the area at the left-hand end of the valve member 210 causes movement of the valve member toward the right, against the atcion of the spring 220 to gradually move the valve land 215 to the right and connect the control passage 207 to the passage 208 which, through bore 202, connects with drain whereby to relieve the pressure on the control piston 91a. During this operation, there is still stabilization provided through the restricted passage means provided by the flats on the valve member land 216. Once the pressure is reduced to that below the pressure compensating range, the system returns to a condition wherein the poppet valve member 231 is closed and the valve member 210 is urged by spring 220 to a position wherein the valve land 215 blocks communication between the control passage 207 and the passage 208 leading to drain.

The addition of the second stage in the embodiment of FIGS. and 6 has provided a pressure compensating control, particularly efiective in smaller capacity pumps wherein it is diflicult to provide stability and pressure compensation without bigger losses of fluid. The addition of the second stage has enabled the use of a much higher rate spring 220 than the spring 131 in the embodiment of FIGS. 1 to 4. Although not to be considered as limiting and only for purposes of illustration, in constructions of the two types disclosed a spring having a rate of approximately 460 pounds per inch has been found suitable for spring 131, while a spring having a rate of 1,000 pounds per inch is suitable for the embodiment of FIGS. 5 and 6. This higher rate spring reduces oscillation of the valve member 210 in response to pump pressure changes and has minimized oscillation of pressure and volume of pump relative to pump pres sure changes on the valve member 210.

We claim:

1. A vane type pump comprising: a rotor with a plurality of vanes and pump inlet and outlet passages; a ring surrounding said rotor and movable between a deadhead position in concentric relation with the rotor and a plurality of non-concentric pumping positions; means to control the ring position including a control piston and a bias piston subject to system pressure at all times and of a lesser area than the control piston, and a three-way valve responsive to system pressure to control the pressure of fluid applied to said control piston; and restricted passage means to bypass control by said valve and place the pump outlet passage in communication with said control piston.

2. A vane type pump as defined in claim 1 wherein said restricted passage means comprises a valve member in said valve with a cylindrical land having a flat surface on a portion of the land periphery.

3. A vane type pump as defined in claim 1 wherein said valve has a first connection to the control piston and connections to the pump outlet passage and to tank with lands on the valve member for controlling communication between said connections; spring means urging said valve member in a direction to connect system pressure to the control piston; means responsive to system pressure and overcoming said urging means at a preset pressure to cause a valve land to restrict communication between the control piston and pump outlet passage, and means on said land defining a continuously effective restricted passage between the control piston and the passage.

4. A vane type pump comprising: a rotor with a plurality of vanes and pump inlet and outlet passages; a ring surrounding said rotor and movable between a deadhead position in concentric relation with the rotor and a plurality of non-concentric pumping positions; means responsive to system pressure to control the ring position including a control piston and a bias piston both engaging the ring in opposition to each other, said bias piston being subject to system pressure at all times and the control piston having a greater diameter and subject to a control pressure, and a three-way valve responsive to system pressure to have the control pressure equal system pressure or to be a lesser value Whereby the ring is shifted for pressure compensation of the pump; and restricted passage means placing the control piston in constant communication with pumped fluid to stabilize the control and decrease the recovery time of the ring.

'5. A vane type pump as defined in claim 4 wherein said restricted passage means comprises a valve member in said valve with a cylindrical land having a flat surface on a portion of the land periphery.

6. A vane type pump as defined in claim 4 wherein said valve has a first connection to the control piston and connections to the pump outlet passage and to tank with lands on the valve member for controlling communication between said connections; spring means urging said valve member in a direction to connect system pressure to the control piston; means responsive to system pressure and overcoming said urging means at a preset pressure to cause a valve land to restrict communication between the control piston and pump outlet passage, and means on said land defining a continuously effective restricted passage between the control piston and the passage.

7. A vane type pump comprising: a rotor with a plurality of vanes and pump inlet and outlet passages; a ring surrounding said rotor and movable between a deadhead position in concentric relation with the rotor and a plurality of non-concentric pumping positions; means responsive to system pressure to control the ring position including a control piston and a bias piston both engaging the ring in opposition to each other, said bias piston being subject to system pressure at all times and the control piston having a greater diameter and subject to a control pressure, and a valve responsive to system pressure to have the control pressure equal system pressure or to be a lesser value whereby the ring is shifted for pressure compensation of the pump, said valve having a bore with a first connection to the control piston and second and third connections to the pump outlet passage and tank, respectively, a valve member in said bore with a pair of spaced lands, adjustable spring means set to determine the pressure at which pressure compensation commences and urging the valve member in a direction to have a first of said lands block communication to tank and the other of said lands positioned to permit communication between the pump outlet passage and the control piston, and means directing system pressure on the valve member in a direction to move the valve member against the spring means and cause the first of said lands to permit flow from the control piston to tank; and restricted passage means comprising a surface on said other land spaced from the valve bore a greater distance than the remainder of the land to permit fluid flow therepast at all times to place the control piston in constant communication with the pump outlet passage.

8. A vane type pump comprising; a rotor with a plurality of vanes and pump inlet and outlet passages; a ring surrounding said rotor and movable between a deadhead position in concentric relation with the rotor and a plurality of non-concentric pumping positions; means responsive to system pressure to control the ring position including a control piston, a first valve responsive to system pressure to control the pressure of fluid applied to said control piston during pressure compensation, a second valve settable to determine the pressure at which the pump will begin pressure compensation; and restricted passage means to bypass said first valve and place the pump outlet passage in communication With said control piston at all times.

9. A vane type pump as defined in claim 8 wherein said restricted passage means comprises a valve member in said first valve with a land having an irregular surface.

10. A vane type pump as defined in claim 8 wherein said first valve has a first connection to the control piston and connections to the pump outlet passage and to tank with lands on the valve member of the first valve for controlling communication between said connections; high rate spring means urging said valve member in a direction to connect system pressure to the control piston; means responsive to system pressure and overcommg said urging means at a preset pressure to cause a valve land to restrict communication between the control piston and pump outlet passage, and means on said 9 10 land defining a continuously eifective restricted passage 2,669,935 2/1954 Tucker 103-120(PA) between the control piston and the passage. 2,724,339 11/1955 QC nnor t; a1, 103 120(PA) 11. A vane type pump as defined in claim 10 wherein v2 740 25 4 195 ll 103 12()(PA) said second valve has a pressure responsive valve mem- 2,809,594 10/1957 orshansky JL 03 120 ber, and passage means for connecting the pump outlet 5 2,875,699 3/1959 Hemdon 103 120(PA) passage to said pressure responslve member of the sec- 2878755 3/1959 (yconnor et a1 103 120(PA) 0nd valve including the space housing said high rate p g means. 2,878,756 3/1959 0 Connor et a1. 103120(PA) Refe'ences c'ted MARK NEWMAN, Primary Examiner UNITED STATES PATENTS 10 1,943,929 1/1934 Rayburn 103120(PA) 2,238,062 4/1941 Kendrick 103-120(PA) W. J. GOODLIN, Assistant Examiner

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