JP2000249078A - Variable displacement vane pump - Google Patents

Abstract

(57) [Problem] To provide a variable displacement vane pump capable of obtaining a stable flow rate characteristic even when a load pressure fluctuates. A variable orifice is provided between a discharge-side pump chamber of a vane pump and a discharge port, and a control valve is provided in a first fluid pressure chamber on the outer periphery of a cam ring.
0, the pressure upstream of the variable orifice 25 is introduced into the second fluid pressure chamber 31, while the pressure downstream of the variable orifice 25 is introduced into the second fluid pressure chamber 31 through the annular gap 61.
A variable orifice 25 upstream pressure is introduced via 2. The annular gap 61 is formed between the through hole 3 a of the adapter ring 3 and the second fluid pressure chamber 3 of the cam ring 5 through the through hole 3 a.
It is formed between the outer periphery of the feedback pin 60 and the second side surface. The feedback pin 60 contacts the distal end of the control piston 21 containing the spring 22 on the base end side, and the opening area of the variable orifice 25 is reduced by the retreat of the control piston 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field 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]

2. Description of the Related Art Japanese Patent Application No. 10-248286 filed by the present applicant proposes a variable displacement vane pump used for a power steering device of a vehicle, which can give an appropriate characteristic to a pump discharge flow rate. .

FIG. 4 shows this Japanese Patent Application No. 10-248286.
1 shows a variable displacement vane pump of the present invention. As shown, the vane pump accommodates a cam ring 105 in an adapter ring 103 in a swingable manner.
A rotor 103 having a plurality of vanes 111 is rotatably disposed therein. On both sides of the cam ring 105, a first fluid pressure chamber 131 and a second fluid pressure chamber 132
The eccentricity of the cam ring 105 is determined by the reciprocal expansion and contraction of the fluid pressure chambers 131 and 132.

When the vane pump operates, the vane 111
The pressure of the discharge-side pressure chamber defined by the pressure is reduced through the variable orifice 125 and the second pressure of the cam ring 105 is reduced.
Plunger 12 arranged on the side of fluid pressure chamber 132
1 and then guided to the discharge port 118 for external hydraulic equipment (eg, a power steering device).
Supplied to The distal end of the control plunger 121 penetrates through the through hole 103 a of the adapter ring 103 to reach the second fluid pressure chamber 132, and is further pressed against the side surface of the cam ring 105 by a spring 122 housed inside the control plunger 121. It is in a state of being left.

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 14 whose valve position fluctuates due to this differential pressure
0 operates, and the hydraulic pressure of the discharge-side pressure chamber (upstream pressure of the variable orifice 125) is introduced into the first fluid pressure chamber 131. On the other hand, the control plunger 1 is provided in the second fluid pressure chamber.
Aperture 129A consisting of a gap between 21 and through hole 103a
Alternatively, the throttle 12 provided at the tip of the control plunger 121
The downstream pressure of the variable orifice 125 is introduced via 9B. For this reason, when the differential pressure between the upstream and downstream of the variable orifice 125 increases, the cam ring 105 is pushed back to the second fluid pressure chamber 132 and the eccentric amount decreases, so that the pump discharge flow rate decreases.

Further, the operation of the cam ring 105 causes the control plunger 1 to abut on the side surface of the cam ring 105.
21 retreats, and the proximal end side of the control plunger 121 narrows the opening area of the variable orifice 125.

As described above, in the high-speed rotation region of the pump,
Reduction of eccentricity of cam ring 105 and variable orifice 12
In combination with the effect of reducing the opening area of No. 5, a flow rate characteristic such that the pump discharge flow rate is stabilized at a small value is obtained.

[0008]

However, the variable displacement vane pump disclosed in Japanese Patent Application No. 10-248286 has a variable orifice 1 which is controlled by the pressure of the second fluid pressure chamber 132.
Since it depends only on the hydraulic pressure downstream of 25,
If the load pressure (pressure at the discharge port 118) fluctuates, this pressure fluctuation greatly affects the pressure in the second fluid pressure chamber 132. Therefore, the operation of the cam ring 105 becomes unstable, and as a result, there is a problem that the flow rate characteristics of the pump are not stabilized.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a variable displacement vane pump capable of obtaining a stable flow rate characteristic even when the load pressure fluctuates.

[0010]

According to a first aspect of the present invention, there is provided a cam ring which is eccentric with respect to a drive shaft, a rotor which is housed inside the cam ring and which rotates about the drive shaft, and which is freely expandable and contractible around the outer periphery of the rotor. Multiple vanes provided in the
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, First pressure introducing means for introducing the variable orifice upstream pressure into a first fluid pressure chamber; second pressure introducing means for introducing a pressure corresponding to the rotor rotation speed into the second fluid pressure chamber; A variable orifice provided between the discharge side pump chamber and the discharge port, and a control for contracting the cam ring toward the second fluid pressure chamber to reduce the opening area of the variable orifice. In a variable displacement vane pump including a plunger and a biasing unit for biasing the control plunger toward the cam ring side,
First throttle means for introducing the second pressure introducing means into the second fluid pressure chamber with the variable orifice upstream pressure;
Second throttle means for introducing the downstream pressure of the variable orifice into the second fluid pressure chamber.

In the second invention, the first and second fluid pressure chambers are defined between the outer periphery of the cam ring and the adapter ring, and include a feedback pin substantially coaxial with the control plunger. Through the through hole formed in the adapter ring, one end of the feedback pin is in contact with the control plunger, and the other end is in contact with the cam ring from the second fluid pressure chamber side. The throttle means is constituted by an annular gap formed between the outer periphery of the feedback pin and the through hole.

[0012]

According to the first invention, the variable orifice upstream pressure is introduced into the first fluid pressure chamber by the first pressure introduction means, while the second pressure is introduced into the second fluid pressure chamber. The variable orifice upstream pressure and the variable orifice downstream pressure are introduced by the first and second throttle means constituting the introduction means. Thus, 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. So that
In the high-speed pump transfer region, a flow rate characteristic in which the pump discharge flow rate decreases is obtained. 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 of the second fluid pressure chamber is only the downstream pressure of the variable orifice. Is less affected by the pressure fluctuation even when the load pressure (discharge port) fluctuates as compared with the case where the pressure is introduced. Therefore,
The operation of the cam ring becomes stable, and stable pump flow characteristics can be obtained.

In the second invention, the annular gap for introducing the variable orifice upstream pressure into the second fluid pressure chamber is formed between the feedback pin separated from the control plunger and the through hole. The opening area of the annular 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 appropriately set, and the operation of the cam ring can be appropriately stabilized.

[0014]

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

FIGS. 1 and 2 show a variable displacement vane pump according to this embodiment.

As shown in the figure, the side plate 2 and the adapter ring 3 are accommodated in the substantially circular accommodating recess 1a of the housing 1 from the bottom (the innermost side) side in a stacked state. Inside the adapter ring 3, an annular cam ring 5 is provided with a drive shaft 8 (described later) using the pin 4 as a rotation fulcrum.
It is swingably supported on the left and right of the camera. This cam ring 5
The rotor 6 is accommodated inside the inside. Also, the accommodation recess 1
The open end of “a” is closed by a cover 7, and the side surfaces of the adapter ring 3, the cam ring 5, and the rotor 6 (the side surface opposite to the side plate 2) are sealed by contacting the cover 7.

A through hole 1b is formed in the bottom surface of the housing recess 1a, and a drive shaft 8 is rotatably supported in the through hole 1b via a metal bearing 9. The distal end of the drive shaft 8 penetrates through the side plate 2 and the rotor 6 to reach a support hole 7a formed in the cover 7, and is rotatably supported by the support hole 7a via a metal bearing 10. ing. The rotor 6 is spline-coupled to the drive shaft 8 so as to rotate integrally with the drive shaft 8. The drive shaft 8 is driven to rotate by a power engine (not shown).

Each of the plurality of cutouts formed on the outer periphery of the rotor 6 accommodates the vane 11 such that the vane 11 can be protruded and retracted in the radial direction of the rotor 6. Thus, 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 provided between the vanes 11. Is defined.

The side plate 2 is formed with a kidney type high-pressure groove 13A and a low-pressure groove 14A. High pressure groove 1
3A and the low-pressure groove 14A are formed at symmetrical positions with respect to the drive shaft 8, and face the pump chamber 12 on the discharge side and the suction side, respectively. The cover 7 has a rotor 6
A high-pressure groove 13B and a low-pressure groove 14B of a kidney type are formed at positions opposite to the high-pressure groove 13A and the low-pressure groove 14A on the side of the side plate 2, with the pump chamber 12 on the discharge side and the suction side, respectively. I'm coming.

The high-pressure groove 13A communicates with a high-pressure chamber 16 formed at the bottom (innermost part) of the housing recess 1a through a high-pressure passage 15 that penetrates the side plate 2. This high pressure chamber 1
6 communicates with the discharge port 18 via a variable orifice 25 as described later. The low-pressure concave groove 14B is connected to the suction port 1 through a low-pressure passage 17 formed in the cover 7.
9 (further, tank T).

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 pivot point.
As shown in (1), a position eccentric to the drive shaft 8 can be taken. Thereby, when the rotor 6 rotates in the counterclockwise rotation direction in FIG. 1 with the rotation of the drive shaft 8, the volume of each pump chamber 12 changes with this rotation. And the suction side which expands with this rotation (the low pressure concave grooves 14A, 14B side)
Hydraulic oil is sucked into the pump chamber 12 from the suction port 19, while the hydraulic oil is discharged from the pump chamber 12 on the discharge side (high-pressure concave grooves 13 </ b> A, 13 </ b> B side), which contracts with this rotation, toward the discharge port 18. Is done.

On the side of the housing 1, there is formed a plug hole 1c that opens into the housing recess 1a (specifically, opens into a second fluid pressure chamber 32 described later). This plug hole 1
c is closed when the plug 20 is attached in a screwed state.

A cylinder hole 20a is opened at the tip end of the plug 20 extending toward the accommodation recess 1a, and a 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 base end side. A spring 22 is housed 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 urges the control plunger 21 toward the adapter ring 3.

As described above, the hollow portion 2 of the control plunger 21
By adopting a configuration in which the spring 22 is housed in 1a, the size of the variable displacement pump can be reduced. Even if the spring 22 is made small enough to be accommodated in the plunger hollow portion 21a, as will be described later, the reaction force F1 of the first fluid pressure chamber 31 and the spring force F _S of the spring 22 together with the second fluid Since the reaction force F2 of the pressure chamber 32 opposes, no problem occurs.

A feedback pin 60 is provided on the tip side of the control plunger 21 (on the side of the adapter ring 3).
The control plunger 21 is disposed substantially coaxially. The proximal end of the feedback pin 60 contacts the distal end of the control plunger 21, and the feedback pin 60 passes through the through hole 3 a formed in the adapter ring 3, and the distal end contacts the side surface of the cam ring 5.

With such a configuration, the control plunger 2
1 is transmitted to the cam ring 5 via the feedback pin 60, and the spring 2 in the control plunger 21 is moved.
The spring force of 2 acts to bias the cam ring 5 to its maximum discharge position.

An annular gap 61 is formed between the outer diameter of the feedback pin 60 and the inner diameter of the through hole 3a.
The second fluid pressure chamber 32 communicates with the fluid chamber 27 (downstream of the variable orifice 25) via the annular gap 61. In this case, the control plunger 21 is connected to the adapter ring 3
The feedback pin 60 penetrating through the through hole 3a is different from the case where the control plunger 21 is penetrated through the through hole 3a.
Therefore, when setting the outer diameter of the feedback pin 60 and the inner diameter of the through hole 3a, it is not necessary to consider an assembly error when the control plunger 21 is incorporated into the vane pump. Therefore, the size of the annular gap 61 is
The second fluid pressure chamber 3 can be set in consideration of only the throttle characteristic between the second fluid pressure chamber 32 and the fluid chamber 27.
The accuracy of pressure control 2 is increased.

A recess 2 is provided at a predetermined position on the outer periphery of the plug 20.
0b is formed. An annular fluid chamber 23 is formed in a region surrounded between 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 is opened in the recess 20b. The hydraulic oil from the high pressure chamber 16
The fluid is introduced into the fluid chamber 23 via a fluid passage 36 formed in the housing 1, and further introduced into the cylinder hole 20 a and the plunger hollow portion 21 a via the variable orifice 25. An O-ring 24 is provided at the open end of the plug hole 1c, so that the fluid chamber 23 is securely sealed.

The opening area of the variable orifice 25 is adjusted by the proximal edge 21b of the control plunger 21 which slides in the cylinder bore 20a. That is, the variable orifice 25 overlaps with the proximal edge 21b as the control plunger 21 retreats into the cylinder hole 20a, so that the opening area thereof is reduced.

A plurality of through holes 26 are formed on the side of the control plunger 21. The plunger hollow portion 21a is inserted into the housing recess 1 of the housing 1 through these through holes 26.
a and the fluid chamber 27 formed between the adapter ring 3 at all times. The fluid chamber 27 communicates with the discharge port 18 via the communication passage 28. As a result, the plunger hollow portion 21a is connected to the through hole 26, the fluid chamber 27, and the communication passage 28.
Is always in communication with the discharge port 18.

The space formed by the gap between the adapter ring 3 and the cam ring 5 is provided between the second fluid pressure chamber 32 on the control plunger 21 side and the control plunger 21 by a pin 4 and a seal 30 fixed to the adapter ring 3. And a first fluid pressure chamber 31 on the opposite side. These fluid pressure chambers 31 and 32 are provided with a cam ring 5 having a pin 4 as a fulcrum.
Oscillating causes reciprocal expansion or contraction.

An orifice 62 is provided in the second fluid pressure chamber 32.
And the second fluid pressure chamber 32 communicates with the high pressure chamber 16 side (upstream of the variable orifice 25) via the orifice 62. Further, as described above, the second fluid pressure chamber 32
Is also in communication with the fluid chamber 27 (downstream of the variable orifice 25) via an annular gap 61 (throttle) formed between the feedback pin 60 and the through hole 3a. 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.

A control valve 40 is integrally provided with the variable displacement vane pump.

The spool 41 of the control valve 40 is slidably housed in a cylinder 42 formed in the housing 1 from the base end. The open end of the cylinder 42 is plug 4
3 closed. Base end of spool 41 and cylinder 4
A return spring 44 is interposed between the two bottoms, and the spool 41 is urged toward the plug 43 by the return spring 44.

The spool 41 has a land 41a at the base end and a land 41b near the center in the axial direction. With these land portions 41a and 41b, the cylinder 42 is connected to the low-pressure fluid chamber 45 between the bottom surface of the cylinder 42 and the land portion 41a (the base end of the spool 41) and the land portion 41.
a, 41b between the drain fluid chamber 46 and the land 41b.
And a high-pressure fluid chamber 47 between the plug 43.

The low-pressure fluid chamber 45 communicates with the discharge port 18 downstream of the variable orifice 25 via an orifice 48 and a fluid pressure passage 49. The drain fluid chamber 46 is connected from the drain port 50 to the drain passage 57 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.

Further, the drain fluid chamber 46 and the high-pressure fluid chamber 47 have 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. Through this, it communicates with the first fluid pressure chamber 31.

More specifically, as shown in detail in FIG. 3, an annular groove 53 is formed at substantially the center of the land portion 41b in the spool axial direction so as to make one round around the outer periphery of the land portion 41b.
Further, a slit 54 is cut out along the spool axis direction in the land portion 41b 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 portion 55 of the land portion 41b which is not cut. With such a configuration, in the initial stage of the pump operation, the opening of the fluid pressure passage 51 is formed through the annular groove 53 and the slit 54 through the drain fluid chamber 46.
To the pump speed (high pressure fluid chamber 47).
When the spool 41 (land portion 41b) moves rightward in the drawing as the pump chamber pressure introduced into the high pressure fluid chamber 47 increases, the fluid pressure passage 51 starts to communicate with the high pressure fluid chamber 47. This allows
Hydraulic oil flows from the high-pressure fluid chamber 47 to the drain fluid chamber 46 via the fluid pressure passage 51, and the fluid pressure passage 5
The pressure of the first fluid pressure chamber 31 communicating with 1 is meter-in controlled in accordance with the degree of opening between the high-pressure fluid chamber 47 and the fluid pressure passage 51.

In such a vane pump,
The pump discharge flow rate 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 adjusted freely by changing the shape of the variable orifice 25 and the opening position.
In this case, as described above, the spring 22 is housed inside the plunger hollow portion 21a of the control plunger 21, and the spring 22 and the variable orifice 25 are in a unit of the plug 20 (a unit including the plug 20, the control plunger 21, the spring 22, and the like). , The characteristics of the pump discharge flow rate with respect to the pump rotation speed can be changed extremely easily and at low cost by changing the unit without changing other pump parts.

Next, the overall operation will be described.

In the stop state of the variable displacement vane pump,
The cam ring 5, as shown in FIG.
1 (spring 22) and is at a position that is maximally eccentric toward the first fluid pressure chamber 31. 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 decompressed by the variable orifice 25 and guided to the fluid chamber 27, where the fluid is supplied to the fluid chamber 27 and the communication passage 28.
Through the discharge port 18 to an external hydraulic device (for example, a power steering device).

The hydraulic pressure in the high-pressure chamber 16 is also introduced into the high-pressure fluid chamber 47 of the control valve 40 via the fluid pressure passage 59. In this case, the spool 41 of the control valve 40
In the initial stage of the pump operation (low-speed rotation region where the pump rotation speed is small), the spring force of the spring 46 and the hydraulic pressure of the low-pressure fluid chamber 45 (the hydraulic pressure of the high-pressure chamber 16 is reduced by the variable orifice 25 and the fixed orifice 61). ) Is pushed back to the plug 43 side. For this reason, the annular groove 53 of the land portion 41b is
The pressure in the first fluid pressure chamber 31 is drained through the fluid passage 51, and the cam ring 5 is held at a position that is maximally eccentric to the first fluid pressure chamber 31 side. Up to. Thus, in the low-speed rotation region of the pump, the pump discharge flow rate from the discharge port 18 rapidly increases in proportion to the pump rotation speed.

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 pressure of the high-pressure chamber 16 is increased. Oil pressure (upstream pressure of the variable orifice) is also introduced through the orifice 62.

As described above, 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 high-pressure fluid chamber 47 and 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 (rightward 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 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.

By switching the control valve 40, the first fluid pressure chamber 31 that has been drained up to that time communicates with the high-pressure fluid chamber 47, and the hydraulic pressure rises. Accordingly, the cam ring 5 causes the reaction force F1 based on the oil pressure of the first fluid pressure chamber 31 (the upstream pressure of the variable orifice 25) to increase the oil pressure of the second fluid pressure chamber 32 (the upstream pressure and the downstream pressure of the variable orifice 25). The pressure is pushed back toward the control plunger 21 until the sum of (F2 + Fs) of F2 based on the intermediate pressure of the pressure and the spring force Fs of the spring 22, and the amount of eccentricity decreases.

As the amount of eccentricity of the cam ring 5 decreases, the amount of change in the volume of the pump chamber 12 due to the rotation of the pump decreases, and accordingly, the amount of change in the volume of the pump chamber 12 is proportional to the amount of change in the pump rotation. The pump discharge flow rate (unit discharge flow rate) becomes smaller. Further, when the amount of eccentricity of the cam ring 5 is reduced as described above, the proximal edge 21b of the control plunger 21 that follows the operation of the cam ring 5
As a result, the variable orifice 25 is gradually closed.
As a result, the flow rate of hydraulic fluid supplied through the variable orifice 25 decreases, and the pressure reduction by the variable orifice 25 increases with the decrease in the opening area of the variable orifice 25, and the hydraulic pressure of the second fluid pressure chamber 32 increases. Is lowered, so that the amount of eccentricity of the cam ring 5 is further reduced. The combined effect of the reduction in the amount of eccentricity of the cam ring 5 and the reduction in the opening area of the variable orifice 25 makes it possible to reduce the pump discharge flow rate (unit discharge flow rate x pump rotation speed) in the medium speed rotation region of the pump. It decreases with increasing numbers.

As described above, in the variable displacement vane pump according to the present embodiment, it is possible to easily obtain such a characteristic that the pump discharge flow rate is stabilized at a small value in the high-speed rotation region of the pump. When the present invention is applied to a power steering device, when the vehicle is running at a high speed where the pump rotation speed (engine rotation speed) is high, the pump discharge flow rate can be stabilized (flat) at a constant flow rate with the pump discharge flow rate reduced. The hydraulic assist force from the vehicle can be controlled appropriately. Therefore,
When the vehicle is running at high speed, the steering is stabilized, and energy loss and an increase in hydraulic oil temperature due to unnecessary supply of hydraulic oil can also be prevented.

In such pump flow control, the amount of eccentricity 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.
In the present invention, as a particularly characteristic configuration, 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. Therefore, since the pressure of the second fluid pressure chamber 32 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 supplied to the second fluid pressure chamber 32. As compared with the case where the pressure chamber is introduced, the rate of the influence of the pressure fluctuation of the fluid chamber 27 due to the load pressure fluctuation is small. Therefore, the operation of the cam ring 5 is stable, and stable pump flow characteristics can be obtained.

In this case, the annular gap 61 for introducing the pressure upstream of the variable orifice 25 into the second fluid pressure chamber 32.
Is formed between the feedback pin 61 separated from the control plunger 21 and the through hole 3a, so that the opening area of the annular gap 61 is set without being restricted by an assembly error of the control plunger 21. it can. Therefore, the damping effect by the annular gap 61 can be appropriately set, and the operation of the cam ring 5 can be appropriately stabilized.

In the above embodiment, the variable orifice 25 is opened and closed by the proximal edge 21b of the control plunger 21. However, the present invention is not limited to such an embodiment. A hole may be formed on the side surface of the plunger 20 so as to overlap with the variable orifice 25, and a portion where the variable orifice 25 overlaps the hole may have an opening area of the variable orifice 25.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view of the same.

FIG. 3 is a sectional view showing a part of the control valve.

FIG. 4 is a sectional view showing a conventional variable displacement vane pump.

[Explanation of symbols]

 Reference Signs List 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 portion 21b plunger base 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

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3H040 AA03 BB01 BB11 CC22 DD03 DD23 DD33 3H044 AA02 BB05 CC22 CC25 DD03 DD13 DD33 DD43

Claims (2)

[Claims] 1. A cam ring which is eccentric with respect to a drive shaft, a rotor which is housed inside the cam ring and rotates about the drive shaft, and a plurality of vanes which are extendably provided on the outer periphery of the rotor. A discharge port for supplying working fluid from a discharge-side pump chamber defined between vanes to an external hydraulic device; first and second fluid pressure chambers formed on both sides of the cam ring; First pressure introducing means for introducing the variable orifice upstream pressure into one fluid pressure chamber; second pressure introducing means for introducing a pressure corresponding to the rotor rotation speed into the second fluid pressure chamber; A variable orifice provided between a discharge side pump chamber and the discharge port; and a control valve for contracting the cam ring to move toward the second fluid pressure chamber to reduce an opening area of the variable orifice. And a biasing means for biasing the control plunger toward the cam ring side. A variable displacement vane pump comprising: a second fluid pressure chamber configured to supply the second pressure introducing means to the variable orifice upstream pressure; First aperture means for introducing
And a second throttle means for introducing the variable orifice downstream pressure into the second fluid pressure chamber. 2. The first and second fluid pressure chambers are defined between an outer periphery of the cam ring and an adapter ring, and include a feedback pin substantially coaxial with the control plunger. And the other end of the feedback pin is brought into contact with the control plunger, and the other end of the feedback pin is brought into contact with the cam ring from the second fluid pressure chamber side. 2. The variable displacement vane pump according to claim 1, wherein the variable displacement vane pump is constituted by an annular gap formed between the outer periphery of the feedback pin and the through hole.