JP2012012977A - Variable displacement vane pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation in the confining performance on a working fluid in a pump chamber caused by separation of a vane from a cam surface in a confining region of a variable displacement vane pump.SOLUTION: The variable displacement vane pump 100 varies a discharge volume of a working fluid from a pump chamber 7 by changing an eccentricity quantity of a cam ring 4 with respect to a rotor 2, which changes a diameter from the center of the rotor 2 to the cum surface 4a. The cam ring 4 includes a sucking region 41 that expands the capacity of the pump chamber 7 with rotation of the rotor 2, a discharge region 42 that contracts the capacity of the pump chamber 7, and confining regions 43, 44 disposed between the sucking region 41 and the discharge region 42, where a low pressure in the sucking region 41 and a high pressure in the discharge region 42 are switched to each other. The confining regions 43, 44 are set in such a manner that a pole where increase and decrease in a diameter from the center of the rotor 2 to the cum surface 4a change over each other with the rotation of the rotor 2 appears outside the confining regions 43, 44 regardless of the eccentricity quantity of the cam ring 4.

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 slide in 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 rotates about one point on the outer periphery, thereby decentering the cam ring with respect to the rotor. A vane pump is disclosed in which the discharge volume changes as the amount changes.

  In the vane pump disclosed in Patent Document 1, the diameter from the rotor center to the cam surface increases with the rotation of the rotor in the closed section between the suction port that sucks the working fluid into the pump chamber and the discharge port that discharges the working fluid in the pump chamber. Is set to decrease gradually.

  Further, in the vane pump in which the discharge capacity is changed by the rotation of the cam ring, the cam surface is formed to have a desired curve according to the eccentric amount of the cam ring with respect to the rotor when the cam ring is at a predetermined angle.

Japanese Patent No. 3743929

  However, in the vane pump as in Patent Document 1, when the cam ring rotates and the amount of eccentricity changes, the diameter from the rotor center to the cam surface changes by the amount that the cam ring rotates. Therefore, the diameter from the center of the rotor to the cam surface does not match the radius of curvature of the cam surface, and the vane that is in sliding contact with the cam surface as the rotor rotates cannot instantaneously move back and forth following the cam surface. There is a possibility that the confining performance of the working fluid in the pump chamber is deteriorated by being separated from the cam surface.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to prevent deterioration of the performance of confining the working fluid in the pump chamber due to the separation of the vane from the cam surface in the confinement region. To do.

  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, and a pump chamber defined between the rotor and the cam ring, the cam ring for the rotor In the variable displacement vane pump in which the diameter from the center of the rotor to the cam surface is changed by changing the eccentric amount of the rotor, and the discharge capacity of the working fluid from the pump chamber is changed, the cam ring includes the rotor of the rotor. A suction region that expands the volume of the pump chamber with rotation, a discharge region that contracts the volume of the pump chamber with rotation of the rotor, the suction region, and the discharge And a closed region where the low pressure of the suction region and the high pressure of the discharge region are switched, and the closed region is moved from the center of the rotor with the rotation of the rotor. The extreme point at which the increase or decrease of the diameter to the cam surface is switched is set so as to appear outside the confinement region regardless of the eccentric amount of the cam ring.

  In the present invention, since the pole at which the increase / decrease in the diameter from the center of the rotor to the cam surface is set to appear outside the confinement region, the increase / decrease in the diameter does not change within the confinement region. Therefore, the vane is prevented from separating from the cam surface in the confining region, and deterioration of the confining performance of the working fluid in the pump chamber can be prevented.

It is sectional drawing which shows a cross section perpendicular | vertical to the drive shaft in the variable displacement vane pump which can apply this invention. It is sectional drawing which shows a cross section parallel to the drive shaft in the variable displacement vane pump to which this invention is applicable. It is a figure explaining the confinement area | region of the cam ring in the variable displacement vane pump which can apply this invention. It is a figure explaining the confinement area | region of the cam ring which concerns on embodiment of this invention. It is a figure which shows the change of the diameter from the center of a rotor to a cam surface accompanying rotation of the rotor which concerns on embodiment of this invention. It is a figure explaining the confinement area | region of the cam ring which concerns on other embodiment of this invention. It is a figure which shows the change of the diameter from the center of a rotor to a cam surface accompanying rotation of the rotor which concerns on other 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 to which the present invention can be applied will be described with reference to FIGS. 1 and 2.

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

  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 a cam ring 4 that is slidable and eccentric with respect to the center of the rotor 2.

  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. The pump cover 5 corresponds to the first side member, and the side plate 6 corresponds to the second side member. In addition, since the first and second side members only need to be provided in contact with the side surface of the cam ring 4, for example, without providing the side plate 6, a part of the pump body 10 is used as the second side member. Also good. Further, a pair of side plates 6 may be provided on both side surfaces of the cam ring 4, and each may be used as the first and second side members.

  As shown in FIG. 1, the cam ring 4 is an annular member, and the suction region 41 that expands the volume of the pump chamber 7 that is partitioned between the vanes 3 as the rotor 2 rotates, and the partition between the vanes 3. And a discharge region 42 for contracting the volume of the pump chamber 7. In addition, the cam ring 4 has confined regions 43 and 44 that trap hydraulic fluid in the pump chamber 7 when the pump chamber 7 transitions between the suction region 41 and the discharge region 42. The confinement regions 43 and 44 will be described in detail later with reference to FIG.

  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.

  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 is reduced is formed. The bulging portion 12 defines the minimum amount of eccentricity of the cam ring 4 with respect to the rotor 2. 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 corresponding to the suction region 41 of the pump chamber 7. Further, a discharge port 16 that opens in an arc shape corresponding to the discharge region 42 of the pump chamber 7 is formed in the side plate 6. The suction port 15 and the discharge port 16 are preferably formed in an arc shape similar to the shapes of the suction region 41 and the discharge region 42 of the pump chamber 7 as shown in FIG. 1, but in the suction region 41 and the discharge region 42. Any shape may be used as long as it communicates.

  In addition, the suction port 15 may be formed in the side plate 6 and the discharge port 16 may be formed in the pump cover 5. Further, the suction port 15 and the discharge port 16 may be formed on either the pump cover 5 or the side plate 6.

  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 in communication 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 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.

  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.

  Next, with reference to FIG. 3, the confinement regions 43 and 44 provided on the cam surface 4a of the cam ring 4 will be described.

  The cam surface 4a formed in an annular shape on the inner periphery of the cam ring 4 is not a perfect circle, and the amount of change is so small that it cannot be visually recognized. It is formed in a desired curve shape in which the diameter up to 4a changes in a complicated manner. The rotation angle of the rotor 2 here is a counterclockwise rotation angle when the position where the support pin 13 is provided in the cam ring 4 is 0 degree as shown in FIG.

  The cam surface 4a includes a suction region 41 that expands the volume of the pump chamber 7 as the rotor 2 rotates, a discharge region 42 that contracts the volume of the pump chamber 7 as the rotor 2 rotates, and a suction region 41 and a discharge region. There are closed regions 43 and 44 provided between the region 42 and confining the hydraulic oil in the pump chamber 7. Here, a section that transitions from the suction area 41 to the discharge area 42 is a first confinement area 43, and a section that transitions from the discharge area 42 to the suction area 41 is a second confinement area 44.

  The closed regions 43 and 44 are set in a section obtained by subtracting the thickness of one vane 3 from both ends of the section between the suction port 15 and the discharge port 16, that is, a section X in FIG. 3. More preferably, the closed regions 43 and 44 are set in a section between the end of the adjacent suction port 15 and the end of the discharge port 16, that is, a section Y in FIG.

  In the vane pump 100, when the rotation angle of the rotor 2 is 90 degrees and 270 degrees, a pole point at which the increase or decrease of the diameter from the center of the rotor 2 to the cam surface 4a is locally switched with the rotation of the rotor 2 appears. . This pole will be described in detail later with reference to FIG.

  Hereinafter, with reference to FIG. 4 and FIG. 5, the setting of the 1st confinement area | region 43 and the 2nd confinement area | region 44 which concern on embodiment of this invention is demonstrated.

  As shown in FIG. 4, in the vane pump 100, the first confinement region 43 and the second confinement region 44 are set so as to avoid the angles at which the rotor 2 rotation angles of 90 degrees and 270 degrees appear. The inset areas 43 and 44 are set so that no extreme points appear. In other words, the vane pump 100 is set so that poles appear outside the confinement regions 43 and 44. In other words, the vane pump 100 is set such that extreme points appear in the suction region 41 and the discharge region 42, respectively.

  Specifically, the second confinement region 44 is set to a position before the rotation angle of the rotor 2 reaches 90 degrees, and the vane 3 passes through the second confinement region 44 before the pole appears. Yes. The first confinement region 43 is set before the rotation angle of the rotor 2 reaches 270 degrees, and the vane 3 passes through the first confinement region 43 before the extreme point appears.

  The poles are set so that they appear within 90 degrees before and after the rotation angle of the rotor 2 is 90 degrees and 270 degrees, respectively. If the pole is set within this range, the vane pump 100 can operate normally.

  Next, the operation of the vane pump 100 according to the embodiment of the present invention will be described with reference to curves A to E shown in FIG.

  In FIG. 5, the horizontal axis indicates the rotation angle of the rotor 2, and the vertical axis indicates the diameter from the center of the rotor 2 to the cam surface 4a. Curves A to E shown in FIG. 4 indicate that the eccentric amount of the center of the cam ring 4 with respect to the center of the rotor 2 is 0.5 mm (minimum eccentricity), 1.5 mm, 2.5 mm, 3.5 mm, and 5.5 mm, respectively. Each case at (maximum eccentricity) is shown.

  As shown by the curves A to E, the diameter from the center of the rotor 2 to the cam surface 4a decreases from 0 degrees to 90 degrees, and becomes the minimum at 90 degrees. In this section in which the diameter decreases, the volume of the pump chamber 7 gradually contracts as the diameter decreases, and the hydraulic oil in the pump chamber 7 is discharged from the discharge port 16. The diameter from the center of the rotor 2 to the cam surface 4a increases from 90 degrees to 270 degrees, and reaches a maximum at 270 degrees. In this section where the diameter increases, the volume of the pump chamber 7 is gradually expanded as the diameter increases, and hydraulic oil is sucked from the suction port 15. The diameter from the center of the rotor 2 to the cam surface 4a decreases again from 270 degrees to 360 degrees (0 degrees), and the hydraulic oil in the pump chamber 7 is discharged from the discharge port 16 again.

  As described above, in the vane pump 100, by expanding or reducing the diameter from the center of the rotor 2 to the cam surface 4 a, the hydraulic oil is sucked into the pump chamber 7 in the suction region 41, and the hydraulic oil in the pump chamber 7 is discharged in the discharge region 42. Is being discharged. In the vane pump 100, as the amount of eccentricity of the cam ring 4 increases, the amount of change in the diameter from the center of the rotor 2 to the cam surface 4a also increases, and the discharge capacity increases.

  Next, a description will be given of the extreme points that appear in the change in the diameter from the center of the rotor 2 to the cam surface 4a as the rotor 2 rotates.

  Focusing on the curve C, a flat section in which the diameter from the center of the rotor 2 to the cam surface 4a does not change and maintains a substantially constant value when the rotation angle of the rotor 2 is 90 degrees and around 270 degrees. There is. In this section, the diameter from the center of the rotor 2 to the cam surface 4a coincides with the radius of curvature of the cam surface 4a in the section. Therefore, in this section, the advancement amount of the vane 3 from the rotor 2 is constant and does not reciprocate with respect to the rotor 2.

  In general, in the closed regions 43 and 44, the vane 3 is pressurized between the suction region 41 where the low-pressure hydraulic oil is sucked into the pump chamber 7 and the discharge region 42 where the high-pressure hydraulic oil is discharged from the pump chamber 7. A force for tilting from the side toward the low pressure side is generated. When such a force is applied, the vane 3 is brought into a so-called self-locking state by pressing the low-pressure side surface against the groove of the rotor 2, so that the vane 3 is reciprocated between the groove of the rotor 2 and the vane 3. Increases sliding resistance. When this sliding resistance increases, the operation of the vane 3 reciprocating relative to the rotor 2 may be hindered. Therefore, in the closed regions 43 and 44, when the diameter from the center of the rotor 2 to the cam surface 4a increases or decreases as the rotor 2 rotates, the vane 3 reciprocates following the curve shape of the cam surface 4a. The tip of the vane 3 cannot be separated from the cam surface 4a, and there is a possibility that the hydraulic oil closing performance of the pump chamber 7 is deteriorated.

  Therefore, in the vane pump 100, a section where the diameter from the center of the rotor 2 to the cam surface 4a is constant is provided around the closed regions 43 and 44 when the eccentric amount of the cam ring 4 is 2.5 mm (curve C). Yes. As described above, the setting is made so that the vane 3 does not reciprocate in the closed regions 43 and 44, so that the hydraulic oil is reliably closed in the pump chamber 7. Not only when the eccentric amount of the cam ring 4 is 2.5 mm, there is provided a section where the diameter from the center of the rotor 2 to the cam surface 4a is constant when the cam ring 4 is eccentric by a predetermined eccentric amount. You may set so that it may become the confinement area | regions 43 and 44. FIG.

  Focusing on the other curves A, B, D, and E in the section where the curve C is set to a flat characteristic, when the rotation angle of the rotor 2 is 90 degrees, in the curves A and B, from the center of the rotor 2 A maximum point where the diameter to the cam surface 4a locally increases and decreases appears, and in the curves D and E, there is a minimum point where the diameter from the center of the rotor 2 to the cam surface 4a decreases locally and increases. Has appeared.

  Similarly, when the rotation angle of the rotor 2 is 270 degrees, in the curves A and B, a minimum point appears in which the diameter from the center of the rotor 2 to the cam surface 4a decreases locally and increases, and the curves D and In E, the maximum point where the diameter from the center of the rotor 2 to the cam surface 4a locally increases and decreases appears.

  Thus, the maximum point and the minimum point where the diameter locally increases or decreases are the extreme points. The pole is more conspicuous as the amount of eccentricity relative to the reference amount of eccentricity becomes larger when the amount of eccentricity when a flat section where the diameter from the center of the rotor 2 to the cam surface 4a is constant is set is the reference amount of eccentricity. Appears on. For this reason, the maximum amount of change in diameter at the pole can be reduced by providing a characteristic that sets the amount of eccentricity approximately half of the maximum amount of eccentricity as the reference amount of eccentricity.

  When the pole appears, the vane 3 slidably contacting the cam surface 4 a locally reciprocates with respect to the rotor 2. Such local reciprocation of the vane 3 is performed in a very short time because the rotor 2 is rotated at high speed by driving the engine.

  Specifically, when a minimum point appears, the vane 3 that is in sliding contact with the cam surface 4a is pushed from the cam surface 4a and retracts into the rotor 2 before the minimum point. Thereafter, when passing through the minimum point, the hydraulic oil in the high-pressure chamber 18 advances from the rotor 2 toward the cam surface 4a.

  On the other hand, when the local maximum point appears, the vane 3 slidingly contacting the cam surface 4a advances from the rotor 2 toward the cam surface 4a by the pressure of the hydraulic oil in the high pressure chamber 18 before the local maximum point. Thereafter, when passing through the local maximum point, the tip of the vane 3 is pushed from the cam surface 4 a and retracted to the rotor 2.

  Here, considering the case where the poles appear in the confinement regions 43 and 44, in the confinement regions 43 and 44, as described above, a force for tilting the vane 3 from the high pressure side toward the low pressure side is generated. The sliding resistance between the groove of the rotor 2 and the vane 3 is increased. When the sliding resistance increases, the vane 3 reciprocates in a very short time to follow the cam surface 4a. However, the sliding resistance smoothly reciprocates. It may not be possible.

  Therefore, in the vane pump 100, the first confinement region 43 and the second confinement region 44 are poles depending on the curved shape of the cam surface 4a on the inner periphery of the cam ring 4 or the positions of the suction port 15 and the discharge port 16 with respect to the cam ring 4. Is set not to appear.

  In the case of the eccentric amounts of the curves A and B, in the second confinement region 44, the diameter from the center of the rotor 2 to the cam surface 4a increases. Moreover, in the 1st confinement area | region 43, the diameter from the center of the rotor 2 to the cam surface 4a reduces.

  In the case of the eccentric amount of the curve C, since a section where the diameter from the center of the rotor 2 to the cam surface 4a is substantially constant is set around the pole, the second confinement area 44 and the first confinement area In 43, the diameter from the center of the rotor 2 to the cam surface 4a is substantially constant.

  In the case of the eccentric amounts of the curves D and E, in the second confinement region 44, the diameter from the center of the rotor 2 to the cam surface 4a decreases. Moreover, in the 1st confinement area | region 43, the diameter from the center of the rotor 2 to the cam surface 4a increases.

  As described above, in the vane pump 100, the diameter from the center of the rotor 2 to the cam surface 4a is within the confinement regions 43 and 44 in all cases from the curve A that is the minimum eccentricity to the curve E that is the maximum eccentricity. Either increases, does not change, or decreases. In the vane pump 100, no pole is generated in the confined regions 43 and 44.

  Therefore, in the vane pump 100, regardless of the amount of eccentricity of the cam ring 4, the increase / decrease in the diameter from the center of the rotor 2 to the cam surface 4a is not switched in the closed regions 43 and 44. Therefore, the vane 3 is prevented from separating from the cam surface 4a in the confining regions 43 and 44, and deterioration of the confining performance of the hydraulic oil in the pump chamber 7 can be prevented.

  As shown in FIG. 4, in the vane pump 100, the closed regions 43 and 44 are divided into sections X obtained by reducing the thickness of one vane 3 from both ends of the section between the suction port 15 and the discharge port 16. Set to. However, the confinement regions 43 and 44 are more preferably set in a section between the end portion of the adjacent suction port 15 and the end portion of the discharge port 16, that is, the section Y in FIG.

  When the confinement regions 43 and 44 are set in the section Y, the extreme points appear in the section in which the suction port 15 and the discharge port 16 are formed. As a result, the poles are further separated from the closed regions 43 and 44, and the vanes 3 pass through the poles before the vane 3 passes through the suction port 15 or the discharge port 16 and completely closes the hydraulic oil in the pump chamber 7. Will be. Therefore, the influence of the poles is further suppressed, and the prevention of deterioration of the performance of the hydraulic oil in the pump chamber 7 becomes remarkable.

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

  Since the pole where the increase / decrease of the diameter from the center of the rotor 2 to the cam surface 4a switches is set to appear outside the confinement regions 43 and 44, the increase / decrease of the diameter from the center of the rotor 2 to the cam surface 4a is increased. There is no switching within the confinement regions 43 and 44. Therefore, the vane 3 is prevented from separating from the cam surface 4a in the confining regions 43 and 44, and deterioration of the confining performance of the hydraulic oil in the pump chamber 7 can be prevented.

  Hereinafter, with reference to FIG.6 and FIG.7, the setting of the 1st confinement area | region 143 and the 2nd confinement area | region 144 which concern on other embodiment of this invention is demonstrated. In the embodiment described below, the same reference numerals are given to the same components as those in the above-described embodiment, and a duplicate description will be omitted as appropriate.

  In this embodiment, the setting of the first confinement region 143 and the second confinement region 144 with respect to the rotation angle of the rotor 2 is different from the above-described embodiment.

  As shown in FIG. 6, the second confinement region 144 is set after the rotation angle of the rotor 2 reaches 90 degrees, and the vane 3 passes through the second confinement region 44 after the extreme point appears. ing. The first confinement region 143 is set after the rotation angle of the rotor 2 reaches 270 degrees, and the vane 3 passes through the first confinement region 143 after the extreme point appears.

  Next, with reference to the curves A to E shown in FIG. 7, an operation of setting the first confinement region 143 and the second confinement region 144 according to another embodiment of the present invention will be described.

  As in FIG. 5, in FIG. 7, the horizontal axis represents the rotation angle of the rotor 2, and the vertical axis represents the diameter from the center of the rotor 2 to the cam surface 4a. Curves A to E shown in FIG. 7 indicate that the eccentric amount of the center of the cam ring 4 with respect to the center of the rotor 2 is 0.5 mm (minimum eccentricity), 1.5 mm, 2.5 mm, 3.5 mm, and 5.5 mm, respectively. Each case at (maximum eccentricity) is shown.

  In the case of the eccentric amounts of the curves A and B, in the second confinement region 144, the diameter from the center of the rotor 2 to the cam surface 4a decreases. Moreover, in the 1st confinement area | region 143, the diameter from the center of the rotor 2 to the cam surface 4a increases.

  In the case of the eccentric amount of the curve C, since a section where the diameter from the center of the rotor 2 to the cam surface 4a is substantially constant is set around the pole, the second confinement area 144 and the first confinement area In 143, the diameter from the center of the rotor 2 to the cam surface 4a becomes substantially constant.

  In the case of the eccentric amounts of the curves D and E, in the second confinement region 144, the diameter from the center of the rotor 2 to the cam surface 4a increases. In the first confinement region 143, the diameter from the center of the rotor 2 to the cam surface 4a decreases.

  As described above, also in this embodiment, in all cases from the curve A that is the minimum eccentricity to the curve E that is the maximum eccentricity, the center of the rotor 2 to the cam surface 4a in the confinement regions 143 and 144. Either the diameter of the tube increases, does not change, or decreases. Therefore, no extreme points are generated in the confinement regions 143 and 144.

  Therefore, also in this embodiment, regardless of the amount of eccentricity of the cam ring 4, the increase / decrease of the diameter is not switched in the closed regions 143, 144. Therefore, the vane 3 is prevented from separating from the cam surface 4a in the confining regions 143 and 144, and the deterioration of the confining performance of the hydraulic oil in the pump chamber 7 can be prevented.

  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.

DESCRIPTION OF SYMBOLS 100 Variable displacement type vane pump 2 Rotor 3 Vane 4 Cam ring 4a Cam surface 6 Side plate 7 Pump chamber 10 Pump body 11 Adapter ring 15 Suction port 16 Discharge port 41 Suction area 42 Discharge area 43 First confinement area 44 Second confinement area 143 First confinement region 144 Second confinement region

Claims (4)

A rotor coupled to the drive shaft;
A plurality of vanes provided so as to be capable of reciprocating in the radial direction with respect 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,
In the variable displacement vane pump in which the diameter from the center of the rotor to the cam surface changes by changing the amount of eccentricity of the cam ring with respect to the rotor, and the discharge capacity of the working fluid from the pump chamber changes.
The cam ring is
A suction region that expands the volume of the pump chamber as the rotor rotates;
A discharge region that shrinks the volume of the pump chamber as the rotor rotates;
A closed region provided between the suction region and the discharge region, wherein the low pressure of the suction region and the high pressure of the discharge region are switched;
In the confinement region, the extreme point where the increase / decrease of the diameter from the center of the rotor to the cam surface is switched with the rotation of the rotor appears outside the confinement region regardless of the eccentric amount of the cam ring. A variable displacement vane pump characterized by being set to A suction port that opens in correspondence with the suction region of the pump chamber;
A discharge port that opens corresponding to the discharge region of the pump chamber,
2. The variable displacement vane pump according to claim 1, wherein the confinement region is a section obtained by reducing the thickness of the vane from each end of the section between the suction port and the discharge port. A suction port that opens in correspondence with the suction region of the pump chamber;
A discharge port that opens corresponding to the discharge region of the pump chamber,
2. The variable displacement vane pump according to claim 1, wherein the confinement region is a section between the suction port and the discharge port. A first side member that contacts one side of the rotor and the cam ring, and a second side member that contacts the other side,
The said suction port is formed in either one of said 1st side member and said 2nd side member, The said discharge port is formed in the other, The Claim 2 or 3 characterized by the above-mentioned. Variable displacement vane pump.

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