JP3798172B2 - Variable displacement vane pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a variable displacement vane pump used for, for example, a power steering device of a vehicle.
[0002]
[Prior art]
Japanese Patent Application No. 10-248286 proposed by the present applicant has proposed a variable displacement vane pump used in a power steering device of a vehicle and the like that can give an appropriate characteristic to the pump discharge flow rate.
[0003]
FIG. 4 shows a variable displacement vane pump disclosed in Japanese Patent Application No. 10-248286. As illustrated, the vane pump is configured such that a cam ring 105 is swingably accommodated in an adapter ring 103, and a rotor 106 including a plurality of vanes 111 is rotatably disposed in the cam ring 105. . A first fluid pressure chamber 131 and a second fluid pressure chamber 132 are defined on both sides of the cam ring 105, and the eccentric amount of the cam ring 105 is determined by reciprocal expansion and contraction of the fluid pressure chambers 131 and 132. .
[0004]
When the vane pump is actuated, the hydraulic pressure in the discharge side pressure chamber defined by the vane 111 is reduced through the variable orifice 125 and inside the control plunger 121 disposed on the second fluid pressure chamber 132 side of the cam ring 105. Is further introduced into the discharge port 118 and supplied to an external hydraulic device (for example, a power steering device). The tip of the control plunger 121 passes through the through hole 103a of the adapter ring 103 and reaches the second fluid pressure chamber 132, and is further pressed against the side surface of the cam ring 105 by a spring 122 accommodated inside the control plunger 121. It is in the state.
[0005]
When the rotational speed of the vane pump increases and the differential pressure between the upstream pressure and the downstream pressure of the variable orifice 125 increases, the control valve 140 whose valve position fluctuates due to this differential pressure is operated, and the first fluid pressure chamber 131 is The hydraulic pressure in the discharge side pressure chamber (upstream pressure of the variable orifice 125) is introduced. On the other hand, the downstream pressure of the variable orifice 125 is introduced into the second fluid pressure chamber via a restriction 129A formed by a gap between the control plunger 121 and the through hole 103a or a restriction 129B provided at the tip of the control plunger 121. ing. For this reason, when the differential pressure upstream and downstream of the variable orifice 125 increases, the cam ring 105 is pushed back to the second fluid pressure chamber 132 side and the eccentric amount decreases, so that the pump discharge flow rate decreases.
[0006]
Further, the operation of the cam ring 105 causes the control plunger 121 that contacts the side surface of the cam ring 105 to retreat, and the proximal end side of the control plunger 121 narrows the opening area of the variable orifice 125.
[0007]
As described above, in the high-speed rotation region of the pump, a flow rate characteristic in which the pump discharge flow rate is stabilized at a small value can be obtained by combining the effect of reducing the eccentric amount of the cam ring 105 and the reduction of the opening area of the variable orifice 125.
[0008]
[Problems to be solved by the invention]
However, the variable displacement vane pump disclosed in Japanese Patent Application No. 10-248286 is dependent on only the hydraulic pressure downstream of the variable orifice 125 for the pressure in the second fluid pressure chamber 132. If the pressure of the second fluid pressure chamber fluctuates, this pressure fluctuation greatly affects the pressure of the second fluid pressure chamber 132. For this reason, the operation of the cam ring 105 becomes unstable, and as a result, there is a problem that the flow rate characteristic of the pump is not stable.
[0009]
The present invention has been made paying attention to such problems, and an object of the present invention is to provide a variable displacement vane pump that can obtain a stable flow rate characteristic even when the load pressure fluctuates.
[0010]
[Means for Solving the Problems]
In the first invention, a cam ring that can be eccentric with respect to the drive shaft, a rotor that is housed inside the cam ring and rotates around the drive shaft, and a plurality of vanes that are provided on the outer periphery of the rotor so as to be extendable and retractable. a discharge port for supplying working fluid to an external hydraulic device from the discharge-side pump chamber defined between these vanes, the first and second fluid pressure chambers formed on both sides of the cam ring, the A variable orifice provided between a discharge-side pump chamber and the discharge port; first pressure introducing means for introducing the variable orifice upstream pressure into the first fluid pressure chamber; and the second fluid pressure chamber. And a second pressure introduction means for introducing a pressure corresponding to the number of rotations of the rotor, and a control for shrinking the cam ring following the operation of the cam ring toward the second fluid pressure chamber to narrow the opening area of the variable orifice. Plastic And a biasing means for biasing the control plunger toward the cam ring side, the second pressure introducing means, the variable orifice upstream pressure being applied to the second fluid pressure chamber. The first throttle means to be introduced and the second throttle means to introduce the variable orifice downstream pressure into the second fluid pressure chamber.
[0011]
In the second invention, the first and second fluid pressure chambers are defined between an outer periphery of the cam ring and an adapter ring, and are provided with a feedback pin substantially coaxially with the control plunger, and the feedback pin is connected to the adapter. A through hole formed in the ring; one end of the feedback pin is brought into contact with the control plunger; the other end is brought into contact with the cam ring from the second fluid pressure chamber side; and the second throttle means Is formed from an annular gap formed between the outer periphery of the feedback pin and the through hole.
[0012]
Operation and effect of the invention
In the first invention, the variable orifice upstream pressure is introduced into the first fluid pressure chamber by the first pressure introducing means, while the second fluid pressure chamber includes the first pressure constituting the second pressure introducing means. The second orifice means introduces a variable orifice upstream pressure and a variable orifice downstream pressure. As a result, when the pump enters the high-speed rotation region and the pressure difference between the upstream and downstream of the variable orifice increases, the second fluid pressure chamber shrinks, the eccentric amount of the cam ring decreases, and the opening area of the variable orifice decreases. Therefore, a flow rate characteristic in which the pump discharge flow rate decreases can be obtained in the pump high-speed transfer region. In this case, since the intermediate pressure between the upstream pressure and the downstream pressure of the variable orifice is introduced into the second fluid pressure chamber, the pressure in the second fluid pressure chamber is limited to the downstream pressure of the variable orifice. Compared with the case where the pressure is introduced, even when the load pressure (discharge port) fluctuates, the proportion affected by this pressure fluctuation is small. Therefore, the operation of the cam ring becomes stable, and a stable pump flow rate characteristic can be obtained.
[0013]
Further, since the second aspect of the invention, the annular gap for introducing a variable orifice under fluid pressure to the second fluid pressure chamber, the control plunger is that formed between the through hole and separated feedback pin, cyclic The opening area of the gap can be set without being restricted by an assembly error of the control plunger. Therefore, the damping effect by the annular gap can be set appropriately, and the operation of the cam ring can be appropriately stabilized.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0015]
1 and 2 show a variable displacement vane pump according to the present embodiment.
[0016]
As shown in the drawing, the side plate 2 and the adapter ring 3 are accommodated in a laminated state in the substantially circular accommodating recess 1a of the housing 1 from the bottom surface (side surface of the innermost portion). An annular cam ring 5 is supported on the inner side of the adapter ring 3 so as to be swingable to the left and right of a drive shaft 8 to be described later with the pin 4 as a pivot. A rotor 6 is accommodated inside the cam ring 5. The opening end of the housing recess 1a is sealed by the cover 7, and the side surfaces (side surfaces opposite to the side plate 2) of the adapter ring 3, the cam ring 5, and the rotor 6 are in contact with the cover 7 and sealed.
[0017]
A through hole 1 b is formed in the bottom surface of the housing recess 1 a, and the drive shaft 8 is rotatably supported via the metal bearing 9 in the through hole 1 b. Further, the front end side of the drive shaft 8 passes through the side plate 2 and the rotor 6 and reaches a support hole 7 a formed in the cover 7, and is rotatably supported by the support hole 7 a via the metal bearing 10. ing. The rotor 6 is spline-coupled to the drive shaft 8 and rotates integrally with the drive shaft 8. The drive shaft 8 is rotationally driven by a power engine (not shown).
[0018]
The vanes 11 are accommodated in the plurality of notches formed on the outer periphery of the rotor 6 so as to be able to protrude and retract in the radial direction of the rotor 6. As a result, when the rotor 6 is rotated by the rotation of the drive shaft 8, the tip of the vane 11 extending from the notch comes into contact with the inner peripheral surface of the cam ring 5, and a plurality of pump chambers 12 are interposed between the vanes 11. Is defined.
[0019]
The side plate 2 is formed with a kidney type high-pressure groove 13A and a low-pressure groove 14A. The high-pressure groove 13A and the low-pressure groove 14A are formed at symmetrical positions with the drive shaft 8 in between so as to face the pump chambers 12 on the discharge side and the suction side, respectively. The cover 7 is provided with a Kidney-type high-pressure groove 13B and a low-pressure groove 14B at positions facing the high-pressure groove 13A and the low-pressure groove 14A on the side plate 2 with the rotor 6 interposed therebetween. It faces the pump chamber 12 on the side and the suction side.
[0020]
The high-pressure groove 13 </ b> A communicates with a high-pressure chamber 16 formed at the bottom (most innermost portion) of the housing recess 1 a through a high-pressure passage 15 that penetrates the side plate 2. The high pressure chamber 16 communicates with the discharge port 18 via a variable orifice 25 as will be described later. Further, the low pressure concave groove 14 </ b> B communicates with the suction port 19 (and further the tank T) via the low pressure passage 17 formed in the cover 7.
[0021]
As described above, the cam ring 5 can swing to the left and right of the drive shaft 8 with the pin 4 as a rotation fulcrum, and can take an eccentric position with respect to the drive shaft 8 as shown in FIG. As a result, when the rotor 6 rotates counterclockwise in FIG. 1 along with the rotation of the drive shaft 8, the volume of each pump chamber 12 changes with this rotation. Then, the hydraulic fluid from the suction port 19 is sucked into the pump chamber 12 on the suction side (low pressure concave grooves 14A and 14B side) that expands with this rotation, while the discharge side (high pressure concave grooves 13A and 13B) shrinks with this rotation. The hydraulic fluid is discharged from the pump chamber 12 on the side toward the discharge port 18.
[0022]
A plug hole 1c is formed in a side portion of the housing 1 so as to open into the housing recess 1a (specifically, open into a second fluid pressure chamber 32 described later). The plug hole 1c is closed when the plug 20 is attached in a screwed state.
[0023]
A cylinder hole 20a is opened at the distal end side of the plug 20 extending toward the accommodation recess 1a, and the control plunger 21 is slidably accommodated in the cylinder hole 20a. The control plunger 21 is formed with a plunger hollow portion 21a that opens to the proximal end side. A spring 22 is accommodated in the plunger hollow portion 21a. The spring 22 is interposed between the bottom surface of the cylinder hole 20a and the bottom surface of the plunger hollow portion 21a, and biases the control plunger 21 toward the adapter ring 3 side.
[0024]
By adopting a configuration in which the spring 22 is accommodated in the hollow portion 21a of the control plunger 21 as described above, the variable displacement pump can be reduced in size. Even if the spring 22 is reduced in size so as to be accommodated in the plunger hollow portion 21a, the reaction force F1 of the first fluid pressure chamber 31 includes the second fluid together with the spring force F _S of the spring 22 as will be described later. Since the reaction force F2 of the pressure chamber 32 opposes, no problem occurs.
[0025]
A feedback pin 60 is provided on the distal end side (adapter ring 3 side) of the control plunger 21 and is disposed substantially coaxially with the control plunger 21. The feedback pin 60 comes into contact with the distal end of the control plunger 21 at the base end, passes through the through hole 3 a formed in the adapter ring 3, and comes into contact with the side surface of the cam ring 5.
[0026]
With such a configuration, the operation of the control plunger 21 is transmitted to the cam ring 5 via the feedback pin 60, and the spring force of the spring 22 in the control plunger 21 urges the cam ring 5 to its maximum discharge position. Works.
[0027]
Further, an annular gap 61 is formed between the outer diameter of the feedback pin 60 and the inner diameter of the through hole 3a, and the second fluid pressure chamber 32 is connected to the fluid chamber 27 (downstream of the variable orifice 25), It communicates via the annular gap 61. In this case, unlike the case where the control plunger 21 is passed through the through hole 3 a of the adapter ring 3, the feedback pin 60 passing through the through hole 3 a is separated from the control plunger 21. When setting the inner diameter of the hole 3a, it is not necessary to consider the assembly error when the control plunger 21 is incorporated into the vane pump. Accordingly, the size of the annular gap 61 can be set in consideration of only the throttling characteristics between the second fluid pressure chamber 32 and the fluid chamber 27, and the pressure control accuracy of the second fluid pressure chamber 32 can be set. Will increase.
[0028]
A recess 20 b is formed at a predetermined position on the outer periphery of the plug 20. An annular fluid chamber 23 is formed in a region surrounded by the recess 20b and the plug hole 1c. In addition, a variable orifice 25 that opens through the side surface of the plug 20 and communicates with the outer peripheral side of the plug 20 and the cylinder hole 20a opens in the recess 20b. The hydraulic oil from the high pressure chamber 16 is introduced into the fluid chamber 23 through the fluid passage 36 formed in the housing 1, and further introduced into the cylinder hole 20 a and the plunger hollow portion 21 a through the variable orifice 25. An O-ring 24 is provided at the opening end of the plug hole 1c so that the fluid chamber 23 is securely sealed.
[0029]
The opening area of the variable orifice 25 is adjusted by the proximal end edge 21b of the control plunger 21 that slides in the cylinder hole 20a. In other words, the variable orifice 25 overlaps with the proximal edge 21b as the control plunger 21 is retracted into the cylinder hole 20a, and the opening area thereof is narrowed.
[0030]
A plurality of through holes 26 are formed on the side surface of the control plunger 21. The plunger hollow portion 21 a always communicates with a fluid chamber 27 formed between the housing recess 1 a of the housing 1 and the adapter ring 3 through these through holes 26. The fluid chamber 27 communicates with the discharge port 18 via the communication path 28. Thus, the plunger hollow portion 21 a is always in communication with the discharge port 18 through the through hole 26, the fluid chamber 27 and the communication passage 28.
[0031]
A space formed by a gap between the adapter ring 3 and the cam ring 5 is separated from the second fluid pressure chamber 32 on the control plunger 21 side by the seal 30 fixed to the pin 4 and the adapter ring 3, and on the side opposite to the control plunger 21. The first fluid pressure chamber 31 is defined. These fluid pressure chambers 31 and 32 are reciprocally expanded or contracted by the swing of the cam ring 5 with the pin 4 as a fulcrum.
[0032]
An orifice 62 is opened in the second fluid pressure chamber 32, and the second fluid pressure chamber 32 communicates with the high pressure chamber 16 side (upstream side of the variable orifice 25) through the orifice 62. Further, as described above, the second fluid pressure chamber 32 is connected to the fluid chamber 27 (downstream of the variable orifice 25) via the annular gap 61 (throttle) formed between the feedback pin 60 and the through hole 3a. It communicates with. As a result, the hydraulic pressure introduced into the second fluid pressure chamber 32 becomes an intermediate pressure between the upstream pressure and the downstream pressure of the variable orifice 25.
[0033]
The variable displacement vane pump is integrally provided with a control valve 40.
[0034]
The spool 41 of the control valve 40 is accommodated in a cylinder 42 formed in the housing 1 so as to be slidable from the base end side. The open end of the cylinder 42 is closed by a plug 43. A return spring 44 is interposed between the base end of the spool 41 and the bottom of the cylinder 42, and the spool 41 is urged toward the plug 43 by the return spring 44.
[0035]
The spool 41 includes a land portion 41a at the base end and a land portion 41b near the center in the axial direction. With these land portions 41a and 41b, the cylinder 42 has a low-pressure fluid chamber 45 between the bottom surface of the cylinder 42 and the land portion 41a (spool 41 base end), a drain fluid chamber 46 between the land portions 41a and 41b, A high pressure fluid chamber 47 between the land portion 41 b and the plug 43 is defined.
[0036]
The low pressure fluid chamber 45 communicates with the discharge port 18 downstream of the variable orifice 25 through an orifice 48 and a fluid pressure passage 49. Further, the drain fluid chamber 46 is connected to the drain passage 57 from the drain port 50 and communicates with the tank T. The high pressure fluid chamber 47 is connected to the fluid pressure passage 58 and communicates with the high pressure chamber 16 via a fluid pressure passage 59 branched from the fluid passage 36.
[0037]
Furthermore, the drain fluid chamber 46 and the high pressure fluid chamber 47 are connected to each other through a fluid pressure passage 51 formed in the housing 1 and opened to the cylinder 42 and an orifice 52 formed in the adapter ring 3 according to the sliding position of the spool 41. The first fluid pressure chamber 31 communicates with the first fluid pressure chamber 31.
[0038]
More specifically, as shown in detail in FIG. 3, an annular groove 53 that makes one round of the outer periphery of the land portion 41b is formed at the approximate center in the spool axis direction of the land portion 41b. Further, a slit 54 is cut out in the land portion 41b along the spool axial direction so that the annular groove 53 communicates with the drain fluid chamber 46. The annular groove 53 and the high-pressure fluid chamber 47 are sealed by a seal part 55 that is not cut out of the land part 41b. With such a configuration, at the initial stage of pump operation, the opening of the fluid pressure passage 51 communicates only with the drain fluid chamber 46 via the annular groove 53 and the slit 54. When the spool pressure (introduced pump chamber pressure) rises and the spool 41 (land portion 41b) moves to the right in the figure, the fluid pressure passage 51 begins to communicate with the high pressure fluid chamber 47. As a result, a flow of hydraulic oil from the high pressure fluid chamber 47 to the drain fluid chamber 46 is generated via the fluid pressure passage 51, and the pressure of the first fluid pressure chamber 31 communicating with the fluid pressure passage 51 is increased. Meter-in control is performed in accordance with the opening between the fluid pressure passage 51 and the fluid pressure passage 51.
[0039]
In such a vane pump, the pump discharge flow characteristics are determined by the shape of the control valve 40, the spring characteristics of the spring 22, the shape and opening position of the variable orifice 25, the opening area of the annular gap 61, the shape of the orifice 62, and the like. It can be freely adjusted by changing the control valve 40, changing the spring 22, and changing the shape or opening position of the variable orifice 25. In this case, as described above, the spring 22 is accommodated in the plunger hollow portion 21a of the control plunger 21, and the spring 22 and the variable orifice 25 are in the unit of the plug 20 (unit comprising the plug 20, the control plunger 21, the spring 22 and the like). Therefore, the characteristic change of the pump discharge flow rate with respect to the pump rotational speed can be performed very easily and at a low cost without changing other pump parts by replacing the unit.
[0040]
Next, the overall operation will be described.
[0041]
In the stopped state of the variable displacement vane pump, the cam ring 5 is biased by the control plunger 21 (spring 22) and is at a position eccentric to the maximum at the first fluid pressure chamber 31 side, as shown in FIG. When the vane pump is operated from this state, hydraulic oil is discharged from the pump chamber 12 to the high pressure chamber 16 as the rotor 6 rotates. The hydraulic oil in the high pressure chamber 16 is depressurized by the variable orifice 25 and guided to the fluid chamber 27, and is supplied from the discharge port 18 to an external hydraulic device (for example, a power steering device) through the fluid chamber 27 and the communication path 28. The
[0042]
The hydraulic pressure in the high pressure chamber 16 is also introduced into the high pressure fluid chamber 47 of the control valve 40 through the fluid pressure passage 59. In this case, the spool 41 of the control valve 40 is configured so that the spring force of the return spring 44 and the hydraulic pressure of the low-pressure fluid chamber 45 (the hydraulic pressure of the high-pressure chamber 16 are variable orifices) at the initial stage of pump operation (low-speed rotation region where the pump speed is small). 25 and the pressure reduced by the fixed orifice 61). For this reason, the annular groove 53 of the land portion 41b is positioned so as to overlap with the opening of the fluid passage 51, the pressure of the first fluid pressure chamber 31 is drained through the fluid passage 51, and the cam ring 5 is The fluid pressure chamber 31 is held at the position eccentrically maximally. As a result, in the low-speed rotation region of the pump, the pump discharge flow rate from the discharge port 18 increases rapidly in proportion to the pump rotation speed.
[0043]
In such a pump operation, the pressure of the fluid chamber 27 (downstream pressure of the variable orifice 25) is guided to the second fluid pressure chamber 32 through the annular gap 61 and the hydraulic pressure of the high-pressure chamber 16 (variable). The upstream pressure of the orifice) is also introduced through the orifice 62.
[0044]
Thus, when the pump rotation speed increases and reaches the high speed rotation region, the flow rate passing through the variable orifice 25 increases. Accordingly, the differential pressure across the variable orifice 25 increases, and the differential pressure between the pressure in the high-pressure fluid chamber 47 and the pressure in the low-pressure fluid chamber 45 of the control valve 40 increases. As a result, the spool 41 of the control valve 40 is pushed back in the direction of expanding the high-pressure fluid chamber 47 (the right direction in FIG. 1) against the spring force of the return spring 44 and the reaction force from the low-pressure fluid chamber 45. As a result, the annular groove 53 of the land portion 41 b moves from the opening of the fluid passage 51 to the right side in FIG. 1, and the fluid passage 51 communicates with the high-pressure fluid chamber 47.
[0045]
By switching the control valve 40, the first fluid pressure chamber 31 that has been drained until then communicates with the high-pressure fluid chamber 47, and the hydraulic pressure increases. As a result, the cam ring 5 has a reaction force F1 based on the hydraulic pressure of the first fluid pressure chamber 31 (upstream pressure of the variable orifice 25), and the hydraulic pressure of the second fluid pressure chamber 32 (upstream pressure and downstream of the variable orifice 25). The pressure is pushed back to the control plunger 21 until the balance (F2 + Fs) of F2 based on the intermediate pressure) and the spring force Fs by the spring 22 (F2 + Fs) is balanced.
[0046]
When the amount of eccentricity of the cam ring 5 decreases, the amount of change in the volume of the pump chamber 12 accompanying the pump rotation decreases, and accordingly, the pump discharge flow rate for one rotation of the pump proportional to the amount of change in the volume of the pump chamber 12 (Unit discharge flow rate) becomes smaller. Further, when the eccentric amount of the cam ring 5 is reduced in this way, the variable orifice 25 is gradually closed by the proximal end edge 21b of the control plunger 21 following the operation of the cam ring 5. As a result, the flow rate of the supply hydraulic oil through the variable orifice 25 is reduced, and the pressure reduction by the variable orifice 25 is increased as the opening area of the variable orifice 25 is reduced. Is lowered, the amount of eccentricity of the cam ring 5 is further reduced. Such effect of reducing the opening area of the eccentric amount of reduced and variable orifice 25 of the cam ring 5 is waiting phase, the pump discharge flow rate in the middle speed rotation region of the pump (unit discharge flow rate × pump speed), the pump speed Goes down against the rise.
[0047]
As described above, in the variable displacement vane pump of the present embodiment, it is possible to easily obtain a characteristic that the pump discharge flow rate is stabilized at a small value in the high-speed rotation region of the pump. When applied to, the pump discharge flow rate can be stabilized at a constant flow (flat) while the pump discharge flow rate is reduced when the vehicle is running at high speed where the pump rotation speed (engine rotation speed) is high. The assist force can be controlled appropriately. Therefore, when the vehicle is traveling at high speed, the steering is stable, and energy loss and an increase in the operating oil temperature due to unnecessary supply of operating oil can be prevented.
[0048]
In such a pump flow rate control, the eccentric amount of the cam ring 5 varies depending on the pressure balance between the first fluid pressure chamber 31 and the second fluid pressure chamber 32. As a particularly characteristic configuration in the present invention, An intermediate pressure between the upstream pressure and the downstream pressure of the variable orifice 25 is introduced into the second fluid pressure chamber 32. Accordingly, since the pressure in the second fluid pressure chamber 32 also directly depends on the upstream pressure of the variable orifice 25, only the pressure of the fluid chamber 27 (downstream pressure of the variable orifice 25) is applied to the second fluid pressure chamber 32. Compared with the case where it introduces, the ratio which receives the influence of the pressure fluctuation of the fluid chamber 27 by a load pressure fluctuation is small. Therefore, the operation of the cam ring 5 is stable, and a stable pump flow rate characteristic can be obtained.
[0049]
Further, those in this case, the annular gap 61 into the second fluid pressure chamber 32 to introduce the pressure of the variable orifice 25 under flow, the control plunger 21 is formed between the feedback pin 61 which is separated through hole 3a Therefore, the opening area of the annular gap 61 can be set without being restricted by an assembly error of the control plunger 21. Therefore, the damping effect by the annular gap 61 can be set appropriately, and the operation of the cam ring 5 can be stabilized appropriately.
[0050]
Incidentally, in the above embodiment has been configured to open and close the variable orifice 25 at the base end side edge 21b of the control plunger 21, the present invention is not limited to such an embodiment, for example, the control plunger 21 A perforation may be formed on the side surface so as to overlap the variable orifice 25, and a portion where the variable orifice 25 overlaps the perforation may be an opening area of the variable orifice 25.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a sectional view of the same.
FIG. 3 is a cross-sectional view showing a part of the control valve.
FIG. 4 is a cross-sectional view showing a conventional variable displacement vane pump.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing 4 Pin 5 Cam ring 6 Rotor 8 Drive shaft 11 Vane 12 Pump chamber 18 Discharge port 19 Suction port 20 Plug 20a Cylinder hole 21 Control plunger 21a Plunger hollow part 21b Plunger proximal end edge 22 Spring 25 Variable orifice 31 First fluid Pressure chamber 32 Second fluid pressure chamber 40 Control valve 41 Spool 42 Cylinder 44 Return spring 45 Low pressure fluid chamber 46 Drain fluid chamber 47 High pressure fluid chamber 60 Feedback pin 61 Annular gap 62 Orifice

Claims (2)

A cam ring that can be eccentric with respect to the drive shaft;
A rotor housed inside the cam ring and rotating around the drive shaft;
A plurality of vanes provided on the outer periphery of the rotor to be extendable and retractable;
A discharge port for supplying a working fluid from a discharge-side pump chamber defined between these vanes to an external hydraulic device;
First and second fluid pressure chambers formed on both sides of the cam ring;
A variable orifice provided between the discharge side pump chamber and the discharge port;
First pressure introducing means for introducing the variable orifice upstream pressure into the first fluid pressure chamber;
Second pressure introducing means for introducing a pressure corresponding to the number of rotations of the rotor into the second fluid pressure chamber;
A control plunger that contracts following the operation of the cam ring toward the second fluid pressure chamber to narrow the opening area of the variable orifice;
Biasing means for biasing the control plunger toward the cam ring;
In variable displacement vane pump with
The second pressure introducing means includes a first throttle means for introducing the variable orifice upstream pressure into the second fluid pressure chamber, and a second for introducing the variable orifice downstream pressure into the second fluid pressure chamber. A variable displacement vane pump characterized by comprising a throttle means. The first and second fluid pressure chambers are defined between the outer periphery of the cam ring and an adapter ring, and are provided with a feedback pin substantially coaxially with the control plunger, and a through hole in which the feedback pin is formed in the adapter ring And the one end of the feedback pin is brought into contact with the control plunger, the other end is brought into contact with the cam ring from the second fluid pressure chamber side, and the second restricting means is connected to the outer periphery of the feedback pin. 2. The variable displacement vane pump according to claim 1, wherein the variable displacement vane pump is configured by an annular gap formed between the through holes.

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