JP5583492B2 - Variable displacement vane pump - Google Patents

Description

  The present invention relates to a variable displacement vane pump used as a fluid pressure supply source in a fluid pressure device.

  Some conventional variable displacement vane pumps (hereinafter simply referred to as “vane pumps”) change the pump discharge capacity by changing the eccentric amount of the cam ring with respect to the rotor.

  In Patent Document 1, a plurality of vanes whose tips are in sliding contact with the cam surface on the inner periphery of the cam ring are provided so as to be able to reciprocate on the rotor, and the cam ring swings about one point on the outer periphery as a fulcrum. A vane pump is disclosed in which the discharge volume changes as the amount changes.

  In the vane pump of Patent Document 1, a first fluid pressure chamber and a second fluid pressure chamber are defined between an inner peripheral surface of an adapter ring that is fixed to the pump body and encloses the outer periphery of the cam ring, and an outer peripheral surface of the cam ring. The cam ring oscillates due to the pressure difference between the hydraulic oil guided to the first fluid pressure chamber and the second fluid pressure chamber.

JP 2010-1810 A

  In the vane pump disclosed in Patent Document 1, the cam ring swings due to a pressure difference between the first fluid pressure chamber and the second fluid pressure chamber, and therefore, the response of the discharge capacity is determined between the first fluid pressure chamber and the second fluid pressure chamber. Determined by the pressure difference.

  An object of the present invention is to improve the responsiveness of the discharge capacity of a variable displacement vane pump.

The present invention relates to a rotor coupled to a drive shaft, a plurality of vanes provided so as to be capable of reciprocating in the radial direction with respect to the rotor, and a cam on the inner circumference as the rotor is accommodated. A cam ring that slides on the surface of the vane and is eccentric with respect to the center of the rotor, a pump chamber defined between the rotor and the cam ring, and a part of the outer periphery of the cam ring. A first fluid pressure chamber defined to face and a second fluid pressure chamber provided to face the first fluid pressure chamber across the cam ring and defined to face a part of the outer periphery of the cam ring And a control valve for controlling a fluid pressure guided to the first fluid pressure chamber and the second fluid pressure chamber , wherein the cam ring is rotated along with the rotation of the rotor. Vomiting to shrink the volume of A first pressure receiving portion on which the pressure of the working fluid acts to decenter the cam ring in a direction in which the discharge capacity discharged from the pump chamber increases, and the pump chamber from the pump chamber A second pressure receiving portion on which the pressure of the working fluid that decenters the cam ring in a direction in which the discharged discharge volume decreases, and the pressure receiving area between the first pressure receiving portion and the second pressure receiving portion is different. And is generated by the difference between the pressure difference between the first fluid pressure chamber and the second fluid pressure chamber controlled by the control valve and the pressure receiving area in the first pressure receiving portion and the second pressure receiving portion. The first fluid pressure chamber and the second fluid pressure chamber expand and contract only by force, and the cam ring is eccentric with respect to the rotor, whereby the discharge capacity of the working fluid discharged from the pump chamber Characterized in that it changes.

  In the present invention, the pressure of the working fluid that decenters the cam ring in the direction in which the discharge pressure discharged from the pump chamber increases, and the pressure of the working fluid that decenters the cam ring in the direction in which the discharge capacity decreases. A difference was provided in the pressure receiving area with the acting second pressure receiving portion. As a result, the cam ring receives a force that is eccentric in the direction of increasing or decreasing the discharge capacity due to the pressure of the working fluid in the pump chamber.

  Therefore, the swing of the cam ring due to the pressure difference between the first fluid pressure chamber and the second fluid pressure chamber is assisted by the pressure of the working fluid in the pump chamber, and the responsiveness of the discharge capacity of the variable displacement vane pump can be improved.

It is sectional drawing which shows a cross section perpendicular | vertical to the drive shaft in the variable displacement vane pump which concerns on embodiment of this invention. It is sectional drawing which shows the cross section parallel to the drive shaft in the variable displacement vane pump which concerns on embodiment of this invention. It is a figure which shows the state which attached the cam ring and the adapter ring to the side plate which concerns on embodiment of this invention. It is a front view of the side plate which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a variable displacement vane pump 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

  A variable displacement vane pump (hereinafter simply referred to as a “vane pump”) 100 is a hydraulic device (fluid pressure device) mounted on a vehicle, for example, a hydraulic pressure (fluid pressure) supply source such as a power steering device or a continuously variable transmission. It is used as

  In the vane pump 100, the power of an engine (not shown) is transmitted to the drive shaft 1, and the rotor 2 connected to the drive shaft 1 rotates. In FIG. 1, the rotor 2 rotates counterclockwise.

  The vane pump 100 houses a plurality of vanes 3 provided so as to be capable of reciprocating in the radial direction with respect to the rotor 2, and the rotor 2, and the distal end portion of the vane 3 on the inner cam surface 4 a as the rotor 2 rotates. And a cam ring 4 that is slidable and eccentric with respect to the center of the rotor 2.

  In the rotor 2, slits 2b having openings on the outer peripheral surface are radially formed at predetermined intervals, and the vanes 3 are slidably inserted into the slits 2b. A back pressure chamber 2a into which pump discharge pressure is guided is defined on the proximal end side of the slit 2b. The vane 3 is pressed in the direction of protruding from the slit 2b by the pressure of the back pressure chamber 2a.

  As shown in FIG. 2, the drive shaft 1 is rotatably supported by the pump body 10 via a bush 27. The pump body 10 is formed with a pump housing recess 10 a for housing the cam ring 4. A seal 20 is provided at an end of the pump body 10 to prevent leakage of lubricating oil between the outer periphery of the drive shaft 1 and the inner periphery of the bush 27.

  A side plate 6 that abuts against one side of the rotor 2 and the cam ring 4 is disposed on the bottom surface 10b of the pump housing recess 10a. The opening of the pump housing recess 10 a is sealed by a pump cover 5 that contacts the rotor 2 and the other side of the cam ring 4. The pump cover 5 is formed with a circular inlay portion 5 a that fits into the pump receiving recess 10 a, and the end surface of the inlay portion 5 a abuts on the other side of the rotor 2 and the cam ring 4. The pump cover 5 is fastened to the flange portion 10c of the pump body 10 via bolts 8 (see FIG. 1).

  In this way, the pump cover 5 and the side plate 6 are arranged with the both sides of the rotor 2 and the cam ring 4 sandwiched therebetween. Thereby, a pump chamber 7 partitioned by the vanes 3 is defined between the rotor 2 and the cam ring 4. These pump cover 5 and side plate 6 correspond to side members. In addition, since the side member only needs to be provided in contact with the side surface of the cam ring 4, for example, a part of the pump body 10 may be used as the side member without providing the side plate 6.

  As shown in FIG. 1, the cam ring 4 is an annular member, formed corresponding to a suction port 15 described later, and a suction region 41 that expands the capacity of the pump chamber 7 as the rotor 2 rotates, which will be described later. And a discharge region 42 formed corresponding to the discharge port and contracting the capacity of the pump chamber 7 as the rotor 2 rotates. Further, the cam ring 4 has confined regions 43 and 44 for confining hydraulic oil in the pump chamber 7 when the pump chamber 7 transitions between the suction region 41 and the discharge region 42.

  The pump chamber 7 sucks the working oil (working fluid) in the suction area 41 and discharges the working oil in the discharge area 42.

  An annular adapter ring 11 is fitted on the inner peripheral surface of the pump housing recess 10 a so as to surround the cam ring 4. Further, the adapter ring 11 is sandwiched between the pump cover 5 and the side plate 6 on both sides as in the rotor 2 and the cam ring 4 (see FIG. 2).

  On the inner peripheral surface of the adapter ring 11, support pins 13 extending in parallel with the drive shaft 1 and having both ends inserted into the pump cover 5 and the side plate 6 are supported. The cam ring 4 is supported by the support pin 13, and the cam ring 4 swings around the support pin 13 inside the adapter ring 11 and is eccentric with respect to the center of the rotor 2. This support pin 13 corresponds to the swing fulcrum of the cam ring 4.

  Since both ends of the support pin 13 are inserted into the pump cover 5 and the side plate 6 and support the cam ring 4, the support pin 13 restricts relative rotation of the pump cover 5 and the side plate 6 with respect to the cam ring 4.

  A groove 11 a extending parallel to the drive shaft 1 is formed at a position axially symmetric with the support pin 13 on the inner peripheral surface of the adapter ring 11. A sealing material 14 is attached to the groove 11a so that the outer peripheral surface of the cam ring 4 is in sliding contact with the cam ring 4 when the cam ring 4 swings.

  Thus, between the outer peripheral surface of the cam ring 4 that is the accommodating space on the outer periphery of the cam ring 4 and the inner peripheral surface of the adapter ring 11, the first fluid pressure chamber 31 and the second fluid are provided by the support pin 13 and the sealing material 14. A fluid pressure chamber 32 is defined.

  The cam ring 4 swings around the support pin 13 as a fulcrum by the pressure difference between the hydraulic fluid in the first fluid pressure chamber 31 and the second fluid pressure chamber 32. When the cam ring 4 swings around the support pin 13 as a fulcrum, the eccentric amount of the cam ring 4 with respect to the rotor 2 changes, and the discharge capacity of the pump chamber 7 changes. When the pressure in the first fluid pressure chamber 31 is larger than the pressure in the second fluid pressure chamber 32, the amount of eccentricity of the cam ring 4 with respect to the rotor 2 becomes small, and the discharge capacity of the pump chamber 7 becomes small. On the other hand, when the pressure in the second fluid pressure chamber 32 is larger than the pressure in the first fluid pressure chamber 31, the amount of eccentricity of the cam ring 4 with respect to the rotor 2 increases, and the discharge capacity of the pump chamber 7 increases. . In this way, in the vane pump 100, the eccentric amount of the cam ring 4 with respect to the rotor 2 changes due to the pressure difference between the first fluid pressure chamber 31 and the second fluid pressure chamber 32, and the discharge capacity changes.

  On the inner peripheral surface of the adapter ring 11 in the second fluid pressure chamber 32, a bulging portion 12 that restricts the movement of the cam ring 4 in a direction in which the amount of eccentricity with respect to the rotor 2 decreases is formed. The bulging portion 12 defines the minimum amount of eccentricity of the cam ring 4 with respect to the rotor 2, and the shaft center of the rotor 2 and the shaft center of the cam ring 4 when the outer peripheral surface of the cam ring 4 is in contact with the bulging portion 12. Maintain a state that is out of place.

  The bulging portion 12 has a minimum eccentricity of the cam ring 4 with respect to the rotor 2 so that the eccentric amount of the cam ring 4 with respect to the rotor 2 does not become zero, that is, even when the outer peripheral surface of the cam ring 4 is in contact with the bulging portion 12. It is ensured and the pump chamber 7 is formed in such a shape that the hydraulic oil can be discharged. Thus, the bulging part 12 ensures the minimum discharge capacity of the pump chamber 7.

  The bulging portion 12 may be formed on the outer peripheral surface of the cam ring 4 in the second fluid pressure chamber 32 instead of being formed on the inner peripheral surface of the adapter ring 11. Further, when the adapter ring 11 is not provided and the first fluid pressure chamber 31 and the second fluid pressure chamber 32 are defined between the outer peripheral surface of the cam ring 4 and the inner peripheral surface of the pump housing recess 10a, The part 12 is formed on the inner peripheral surface of the pump housing recess 10a.

  The pump cover 5 is formed with a suction port 15 that opens in an arc shape to supply hydraulic oil and guide the hydraulic oil into the pump chamber 7. Further, the side plate 6 is formed with a discharge port 16 that opens in an arc shape and guides hydraulic oil in the pump chamber 7 to the hydraulic equipment.

  The suction port 15 is also formed in the same shape on the side plate 6 and communicates with the suction port 15 of the pump cover 5 via the pump chamber 7. Similarly, the discharge port 16 is also formed in the same shape in the pump cover 5 and communicates with the discharge port 16 of the side plate 6 via the pump chamber 7. The specific shape of the discharge port 16 will be described later in detail with reference to FIGS. 3 and 4.

  Since the relative rotation of the pump cover 5 and the side plate 6 with respect to the cam ring 4 is restricted by the support pins 13, displacement of the suction port 15 and the discharge port 16 with respect to the suction region 41 and the discharge region 42 of the pump chamber 7 is prevented.

  As shown in FIG. 2, the suction port 15 is formed to communicate with the suction passage 17 formed in the pump cover 5, and guides the hydraulic oil in the suction passage 17 to the suction region 41 of the pump chamber 7. The discharge port 16 is formed in communication with the high pressure chamber 18 formed in the pump body 10 and guides hydraulic oil discharged from the discharge region 42 of the pump chamber 7 to the high pressure chamber 18.

  The high-pressure chamber 18 is defined by a groove 10d formed by opening in an annular shape on the bottom surface 10b of the pump housing recess 10a with the side plate 6 being closed. The high-pressure chamber 18 is connected to a discharge passage (not shown) that is formed in the pump body 10 and guides hydraulic oil to hydraulic equipment outside the vane pump 100.

  The high pressure chamber 18 communicates with the second fluid pressure chamber 32 via a throttle passage 36 (see FIG. 1), and the hydraulic oil in the high pressure chamber 18 is always guided to the second fluid pressure chamber 32. That is, the cam ring 4 always receives pressure in the direction in which the eccentric amount with respect to the rotor 2 is increased by the second fluid pressure chamber 32.

  Further, since the high pressure chamber 18 is formed in the pump body 10, the side plate 6 is pressed against the rotor 2 and the vane 3 side by the pressure of the hydraulic oil guided to the high pressure chamber 18. Thereby, the clearance of the side plate 6 with respect to the rotor 2 and the vane 3 is reduced, and leakage of hydraulic oil is prevented. Thus, the high pressure chamber 18 also functions as a pressure loading mechanism for preventing leakage of hydraulic oil from the pump chamber 7.

  The high pressure chamber 18 communicates with a back pressure channel 50 formed in the side plate 6, and the back pressure chamber 2 a supplies hydraulic oil for urging the vane 3 toward the cam surface 4 a via the back pressure channel 50. To supply. As shown in FIG. 1, a valve housing hole 29 is formed in the pump body 10 in a direction orthogonal to the axial direction of the drive shaft 1. The valve accommodating hole 29 accommodates the control valve 21 that controls the pressure of the hydraulic fluid in the first fluid pressure chamber 31 and the second fluid pressure chamber 32.

  The control valve 21 includes a spool 22 slidably inserted into the valve housing hole 29, a first spool chamber 24 defined between one end of the spool 22 and the bottom of the valve housing hole 29, A second spool chamber 25 defined between the other end and the plug 23 that seals the valve housing hole 29; and a direction in which the volume of the second spool chamber 25 is expanded in the second spool chamber 25. And a return spring 26 for urging the spool 22.

  The spool 22 is a ring formed between the first land portion 22a and the second land portion 22b that slide along the inner peripheral surface of the valve housing hole 29, and the first land portion 22a and the second land portion 22b. A groove 22c.

  The first spool chamber 24 includes a first stopper that abuts against the bottom of the valve housing hole 29 and restricts the movement of the spool 22 beyond a predetermined level when the spool 22 moves in a direction in which the volume of the first spool chamber 24 contracts. The part 22d is coupled to the first land part 22a.

  Also, the second spool chamber 25 has a second stopper portion 22e that abuts against the plug 23 and restricts the movement of the spool 22 beyond a predetermined level when the spool 22 moves in a direction in which the volume of the second spool chamber 25 contracts. Is coupled to the second land portion 22b. The return spring 26 is accommodated in the second spool chamber 25 so as to surround the second stopper portion 22e.

  The control valve 21 communicates with the first fluid pressure passage 33 and the second fluid pressure passage 34 that communicate with the first fluid pressure chamber 31 and the second fluid pressure chamber 32, respectively, with the annular groove 22 c and with the suction passage 17. A drain passage 35 connected to the first spool chamber 24 and a pressure guide passage (not shown) communicating with the high-pressure chamber 18 are connected.

  The first fluid pressure passage 33 and the second fluid pressure passage 34 are formed inside the pump body 10 and are formed through the adapter ring 11.

  The spool 22 stops at a position where the load due to the pressure of the hydraulic oil guided to the first spool chamber 24 and the second spool chamber 25 defined at both ends and the urging force of the return spring 26 are balanced. Depending on the position of the spool 22, the first fluid pressure passage 33 and the second fluid pressure passage 34 are opened and closed by the first land portion 22a and the second land portion 22b, respectively, and the first fluid pressure chamber 31 and the second fluid pressure chamber 32 are opened. The hydraulic oil is supplied and discharged.

  When the total load of the load due to the pressure in the second spool chamber 25 and the urging force of the return spring 26 is larger than the load due to the pressure in the first spool chamber 24, the return spring 26 extends and the spool 22 The portion 22d comes into contact with the bottom of the valve housing hole 29. In this state, as shown in FIG. 1, the first fluid pressure passage 33 is closed by the first land portion 22 a of the spool 22, and the second fluid pressure passage 34 is closed by the second land portion 22 b of the spool 22. It becomes a state. Thereby, the communication between the first fluid pressure chamber 31 and the high pressure chamber 18 is blocked, and the communication between the second fluid pressure chamber 32 and the drain passage 35 is also blocked.

  Here, since a communication path (not shown) communicating with the annular groove 22c is formed in the first land portion 22a, the first fluid pressure passage 33 is in the state closed by the first land portion 22a. The fluid pressure chamber 31 communicates with the drain passage 35 through the first fluid pressure passage 33, the communication passage, and the annular groove 22c. Further, since the hydraulic fluid in the high pressure chamber 18 is always guided to the second fluid pressure chamber 32 through the throttle passage 36, the pressure in the second fluid pressure chamber 32 is larger than the pressure in the first fluid pressure chamber 31. Thus, the amount of eccentricity of the cam ring 4 with respect to the rotor 2 is maximized.

  On the other hand, when the load due to the pressure in the first spool chamber 24 is larger than the total load of the load due to the pressure in the second spool chamber 25 and the urging force of the return spring 26, the return spring 26 is compressed and the spool 22 moves against the urging force of the return spring 26. In this case, the first fluid pressure passage 33 communicates with the first spool chamber 24 and communicates with the pressure guiding passage via the first spool chamber 24. The second fluid pressure passage 34 communicates with the annular groove 22c of the spool 22 and communicates with the drain passage 35 via the annular groove 22c. Accordingly, the first fluid pressure chamber 31 communicates with the high pressure chamber 18, and the second fluid pressure chamber 32 communicates with the drain passage 35. Accordingly, the pressure in the second fluid pressure chamber 32 becomes smaller than the pressure in the first fluid pressure chamber 31, and the cam ring 4 moves in a direction in which the amount of eccentricity with respect to the rotor 2 decreases.

  The communication between the second fluid pressure passage 34 and the annular groove 22 c is performed through a notch 22 f formed in the second land portion 22 b of the spool 22. Therefore, the opening area of the drain passage 35 with respect to the second fluid pressure chamber 32 increases or decreases according to the movement amount of the spool 22.

  As described above, the control valve 21 controls the pressure of the hydraulic fluid in the first fluid pressure chamber 31 and the second fluid pressure chamber 32, and the difference between the front and rear of the orifice (not shown) interposed in the discharge passage. Operates by pressure. The hydraulic oil upstream of the orifice is guided to the first spool chamber 24, and the hydraulic oil downstream of the orifice is guided to the second spool chamber 25.

  That is, the hydraulic oil in the high-pressure chamber 18 is directly guided to the first spool chamber 24 through the pressure guide passage without passing through the orifice, and is guided to the second spool chamber 25 through the orifice. The orifice may be either a variable type or a fixed type as long as it provides resistance to the flow of hydraulic fluid discharged from the pump chamber 7.

  Hereinafter, the discharge port 16 and the suction port 15 according to the embodiment of the present invention will be described with reference to FIGS. 3 and 4.

  First, the shapes of the discharge port 16 and the suction port 15 will be described.

  As shown in FIG. 3, the suction port 15 and the discharge port 16 are each formed in the circular arc shape corresponding to the shape of the cam surface 4a. The suction port 15 and the discharge port 16 are arcuate along the cam surface 4a when the center point of the cam ring 4 and the center point of the rotor 2 (see FIG. 1) coincide, that is, when the eccentric amount of the cam ring 4 is zero. Formed. The state shown in FIG. 3 is a state where the cam ring 4 is eccentric until the discharge capacity of the pump chamber 7 is maximized.

  As shown in FIG. 4, the discharge port 16 is formed so that its circumferential length is biased to one side around the support pin 13. Specifically, the discharge port 16 has a circumferential length between the middle point 16a and the end portion 16c, where the position corresponding to the support pin 13 is a middle point 16a. It is formed to be longer than the circumferential length between them. That is, the discharge port 16 is formed so that the side where the first fluid pressure chamber 31 is provided is longer than the side where the second fluid pressure chamber 32 is provided, with the support pin 13 as the center. In FIG. 4, the discharge port 16 is formed to be biased to the left with the support pin 13 as the center.

  Next, the discharge region 42 and the suction region 41 provided in the cam ring 4 corresponding to the discharge port 16 and the suction port 15 will be described.

  The cam surface 4 a in the discharge region 42 has a first pressure receiving portion 45 to which the hydraulic oil pressure that decenters the cam ring 4 acts in a direction in which the discharge capacity discharged from the pump chamber 7 increases, and the discharge discharged from the pump chamber 7. And a second pressure receiving portion 46 on which the hydraulic oil pressure that decenters the cam ring 4 acts in the direction of decreasing capacity. In FIG. 3, the left side is the first pressure receiving part 45 around the support pin 13, and the right side is the second pressure receiving part 46.

  The first pressure receiving portion 45 is provided on the inner periphery of the cam ring 4 facing the pump chamber 7. The cam ring 4 is subjected to a force that swings in a direction (left side in FIG. 3) in which the discharge capacity discharged from the pump chamber 7 increases due to the pressure of the hydraulic oil in the pump chamber 7 acting on the first pressure receiving portion 45. To do.

  Similarly, the second pressure receiving portion 46 is provided on the inner periphery of the cam ring 4 facing the pump chamber 7. The second pressure receiving portion 46 is formed continuously with the first pressure receiving portion 45 around the position corresponding to the support pin 13 on the cam surface 4a. The cam ring 4 is subjected to a force that swings in the direction in which the discharge capacity discharged from the pump chamber 7 decreases (right side in FIG. 3) due to the pressure of the hydraulic oil in the pump chamber 7 acting on the first pressure receiving portion 45. To do.

  Therefore, a force that swings in one direction by the product of the pressure of the hydraulic oil acting on the first pressure receiving portion 45 and the pressure receiving area of the first pressure receiving portion 45 acts on the cam ring 4 and acts on the second pressure receiving portion 46. A swinging force acts on the other by the product of the pressure of the hydraulic oil and the pressure receiving area of the first pressure receiving portion 46.

  Here, the pressure of the hydraulic oil in the pump chamber 7 in the discharge region 42 is substantially constant because the pump chamber 7 communicates with the discharge port 16. Therefore, when there is a difference in pressure receiving area between the first pressure receiving part 45 and the second pressure receiving part 46, the cam ring 4 has a force acting on the larger pressure receiving area and a force acting on the smaller pressure receiving area. It becomes large compared. Therefore, the cam ring 4 swings around the support pin 13 toward the larger pressure receiving area of the first pressure receiving portion 45 and the second pressure receiving portion 46.

  The first pressure receiving part 45 and the second pressure receiving part 46 are provided corresponding to the discharge port 16. That is, the first pressure receiving part 45 and the second pressure receiving part 46 are provided with a difference in pressure receiving area on which the hydraulic oil pressure in the pump chamber 7 acts. Specifically, the first pressure receiving portion 45 is formed such that the circumferential length is longer than the circumferential length of the second pressure receiving portion 46, and the pressure receiving area on which the hydraulic oil pressure in the pump chamber 7 acts. Is larger than the second pressure receiving portion 46.

  Of the pump chamber 7 defined on the inner periphery of the cam ring 4 due to the difference in pressure receiving area between the first pressure receiving portion 45 and the second pressure receiving portion 46, the cam surface 4a on which the high pressure pump chamber 7 facing the discharge port 16 is located. This range is biased toward the first pressure receiving portion 45 with the support pin 13 as the center. Thereby, the pressure receiving area of the cam surface 4a in the discharge region 42 where the hydraulic oil pressure of the high pressure pump chamber 7 acts is provided on the side where the first fluid pressure chamber 31 is provided, and the second fluid pressure chamber 32 is provided. It becomes larger compared to the side to be.

  Hereinafter, the operation of the discharge port 16 formed in the above shape will be described mainly with reference to FIG.

  When the pressure of the hydraulic oil in the second fluid pressure chamber 32 is adjusted by the control valve 21 (see FIG. 1) to be higher than the pressure of the hydraulic oil in the first fluid pressure chamber 31, the cam ring 4 The pump chamber 7 swings in the direction of increasing the discharge capacity. As described above, the cam ring 4 swings when a pressure difference is generated between the first fluid pressure chamber 31 and the second fluid pressure chamber 32.

  The pressure of the hydraulic oil in the pump chamber 7 acts on the cam surface 4 a of the cam ring 4. The pressure of the hydraulic oil in the pump chamber 7 is higher on the discharge region 42 side having a high pressure than on the suction region 41 side having a low pressure. Therefore, a force that presses the cam ring 4 toward the discharge region 42 (downward in FIG. 3) acts on the cam ring 4 due to the pressure of the hydraulic oil in the pump chamber 7.

  Here, the discharge port 16 is formed larger on the side where the first fluid pressure chamber 31 is provided, with the support pin 13 as the center, compared to the side where the second fluid pressure chamber 32 is provided. Correspondingly, the cam surface 4 a in the discharge region 42 is formed such that the pressure receiving area of the first pressure receiving portion 45 is larger than the pressure receiving area of the second pressure receiving portion 46. As a result, the force that swings the cam ring 4 in the direction in which the discharge capacity discharged from the pump chamber 7 increases is greater than the force that swings the cam ring 4 in the direction that decreases the discharge capacity. Therefore, the cam ring 4 swings around the support pin 13 in the direction in which the discharge capacity discharged from the pump chamber 7 is increased by the hydraulic oil in the pump chamber 7.

  Thereby, the cam ring 4 has a force due to a pressure difference between the first fluid pressure chamber 31 and the second fluid pressure chamber 32 acting on the outer periphery, and a pressure of the hydraulic oil in the pump chamber 7 acting on the inner peripheral cam surface 4a. The first fluid pressure chamber 31 is swung in the contracting direction due to the force generated by the above, and the discharge capacity of the pump chamber 7 is increased.

  From the above, the cam ring 4 is not only based on the pressure difference of the hydraulic oil between the first fluid pressure chamber 31 and the second fluid pressure chamber 32 but also by the pressure of the hydraulic oil in the pump chamber 7 acting on the first pressure receiving portion 45. Swing. Therefore, when the cam ring 4 swings in the direction in which the discharge capacity of the pump chamber 7 increases, the swing is assisted. Therefore, the response when the discharge capacity of the pump chamber 7 is increased can be improved.

  According to the above embodiment, the following effects are obtained.

  The discharge port 16 is formed with a bias toward the side where the first fluid pressure chamber 31 is provided with the support pin 13 as the center. Therefore, the pressure receiving area of the first pressure receiving portion 45 provided on the cam surface 4 a is larger than the pressure receiving area of the second pressure receiving portion 46. As a result, the cam ring 4 receives a force that swings in a direction in which the discharge capacity increases due to the pressure of the hydraulic oil in the pump chamber 7.

  Therefore, when the cam ring 4 swings due to the pressure difference between the first fluid pressure chamber 31 and the second fluid pressure chamber 32 is assisted by the pressure of the hydraulic oil in the pump chamber 7, the discharge capacity of the pump chamber 7 increases. Can improve responsiveness.

  If it is desired to improve the responsiveness when the discharge capacity of the pump chamber 7 becomes small, the discharge port 16 is not biased toward the side where the first fluid pressure chamber 31 is provided, but the second fluid pressure. What is necessary is just to be biased and provided in the side where the chamber 32 is provided. When the discharge port 16 is provided on the side where the second fluid pressure chamber 32 is provided, the suction port 15 is provided on the side where the first fluid pressure chamber 31 is provided.

  As the discharge port 16 is provided in the second fluid pressure chamber 32 in a biased manner, the pressure received by the second pressure receiving portion 46 is applied with a pressure that causes the cam ring 4 to be eccentric in a direction in which the discharge capacity discharged from the pump chamber 7 decreases. The area is larger than the pressure receiving area of the first pressure receiving portion 45. As a result, the force for swinging the cam ring 4 in the direction in which the discharge capacity discharged from the pump chamber 7 decreases becomes larger than the force for swinging the cam ring 4 in the direction in which the discharge capacity increases. Therefore, when the cam ring 4 is swung in the direction of decreasing the discharge capacity of the pump chamber 7, the swing is assisted. Therefore, the response when the discharge capacity of the pump chamber 7 is reduced can be improved.

  As described above, by forming the discharge port 16 so as to be biased to one of the support pins 13 as a center, a difference is provided in the pressure receiving area between the first pressure receiving portion 45 and the second pressure receiving portion 46 of the cam surface 4a. Thereby, the response when the discharge capacity of the pump chamber 7 is increased or decreased can be improved.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

  The vane pump according to the present invention can be applied to a hydraulic pressure supply source such as a power steering device or a transmission.

100 Variable displacement vane pump 1 Drive shaft 2 Rotor 3 Vane 4 Cam ring 4a Cam surface 5 Pump cover 6 Side plate 7 Pump chamber 10 Pump body 11 Adapter ring 13 Support pin 15 Suction port 16 Discharge port 31 First fluid pressure chamber 32 Second Fluid pressure chamber 41 Suction area 42 Discharge area 45 First pressure receiving part 46 Second pressure receiving part

Claims (3)

A rotor coupled to the drive shaft;
A plurality of vanes provided so as to be capable of reciprocating in the radial direction relative to the rotor;
A cam ring that houses the rotor, and that the tip of the vane slides on the inner cam surface as the rotor rotates, and is eccentric with respect to the center of the rotor;
A pump chamber defined between the rotor and the cam ring;
A first fluid pressure chamber defined to face a part of the outer periphery of the cam ring;
A second fluid pressure chamber provided opposite to the first fluid pressure chamber across the cam ring and defined facing a part of the outer periphery of the cam ring;
A variable displacement vane pump comprising: a control valve that controls a fluid pressure guided to the first fluid pressure chamber and the second fluid pressure chamber ;
The cam ring has a discharge region that contracts the volume of the pump chamber as the rotor rotates.
The cam surface in the discharge region is
A first pressure receiving portion on which the pressure of the working fluid that decenters the cam ring in a direction in which the discharge capacity discharged from the pump chamber increases,
A second pressure receiving portion on which the pressure of the working fluid acts to decenter the cam ring in a direction in which the discharge capacity discharged from the pump chamber decreases.
A difference is provided in the pressure receiving area between the first pressure receiving portion and the second pressure receiving portion ,
Only the force due to the pressure difference between the first fluid pressure chamber and the second fluid pressure chamber controlled by the control valve, and the force generated by the difference in pressure receiving area in the first pressure receiving portion and the second pressure receiving portion. That the first fluid pressure chamber and the second fluid pressure chamber expand and contract, and the cam ring is eccentric with respect to the rotor, whereby the discharge capacity of the working fluid discharged from the pump chamber changes. Features variable displacement vane pump. A side member provided in contact with the side surface of the cam ring;
The side member includes a discharge port that guides the working fluid in the pump chamber to a fluid pressure device,
The cam ring is provided so as to be eccentric with respect to the center of the rotor by swinging about a swing fulcrum.
2. The pressure receiving area between the first pressure receiving portion and the second pressure receiving portion is provided by forming the discharge port so as to be biased to one side around the swing fulcrum. The variable displacement vane pump described.   3. The variable displacement vane pump according to claim 1, wherein a pressure receiving area of the first pressure receiving portion is larger than that of the second pressure receiving portion.

Images