JP2000104675A - Variable displacement vane pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly dispose both a valve means acting by following up the rotation of a cam ring, and a cam spring in a variable capacity type vane pump. SOLUTION: This vane pump is equipped with a control valve 2 capable of controlling the flow of working oil being interlocked with the rotation of a cam ring 70, and with a cam spring 26 energizing the cam ring 70 to the direction of its rotation. In this case, by defining a plane connecting the rotation fulcrum Op of the cam spring 26 with the axial center Oc of the cam ring 70, and as a central plane Sy of the cam ring 70 a straight line which is perpendicularly intersected with the supporting control surface Sy of the cam ring 70 so as to be intersected with the axial center Oc of a rotor 50, as to be the supporting orthogonal line Sx of the cam ring 70, the control valve 2 is disposed over the supporting orthogonal line Sx of the cam ring 70, and the cam spring 26 is disposed in parallel with the control valve 2 in the radial direction of the rotor 50.

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 vehicle power steering device.

[0002]

2. Description of the Related Art Conventionally, as a variable displacement vane pump of this type, for example, disclosed in Japanese Patent Application Laid-Open No. H8-200399, a pump ring surrounding each vane is eccentric with respect to a rotor shaft center. The discharge flow rate is increased. By reducing the flow rate of the hydraulic oil returned from the vane pump to the tank in this manner, wasteful energy consumption is reduced.

This vane pump includes a cam spring which rotatably supports a cam ring with respect to a casing and urges the cam ring in a rotating direction, as a variable displacement mechanism for adjusting the pump discharge flow rate. Hydraulic drive means for rotating the cam ring.

The tip of the cam spring is arranged in the radial direction of the rotor so as to abut on the outer peripheral side of the cam ring, so that the amount of sliding of the cam spring with respect to the outer peripheral surface of the cam ring is reduced.

[0005]

However, when such a conventional variable displacement vane pump is provided with valve means for controlling the flow of hydraulic oil in conjunction with the rotation of the cam ring, such a valve means is required. Due to the placement space, the placement space of the cam spring is driven away from the position facing the outer peripheral side of the cam ring to another position, and the sliding distance of the tip end of the cam spring with respect to the outer peripheral surface of the cam ring increases, There is a problem in that the provision of a space for making the casing invites an increase in the size of the casing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a variable displacement vane pump with proper arrangement of a valve spring and a cam spring that follow a rotating cam ring. I do.

[0007]

According to a first aspect of the present invention, a plurality of vanes slidably protruding from a rotating rotor, a cam ring which slidably contacts an outer peripheral end of each vane to define a pump chamber, A variable displacement vane pump including a variable displacement mechanism for rotating a cam ring, valve means for controlling the flow of a working fluid in conjunction with the rotation of the cam ring, and a cam spring for biasing the cam ring in a rotating direction. When the plane connecting the rotation support point Op of the cam spring and the axis Oc of the cam ring is the cam ring center plane Sy, and the straight line orthogonal to the cam ring support center plane Sy and intersecting with the rotor axis Or is the cam ring support orthogonal line Sx, The valve means is arranged on the cam ring support orthogonal line Sx, and the cam spring is arranged in the radial direction of the rotor along with the valve means.

According to a second aspect of the present invention, in the first aspect, a cam pressure chamber which contracts as the cam ring rotates to the side where the pump discharge flow rate decreases is defined around the cam ring, and the cam pressure chamber is formed in the cam pressure chamber. A relief valve is provided for releasing the driving pressure of the cam pressure chamber when the driving pressure of the guided cam ring rises above a predetermined value, and the relief valve is disposed inside the cam spring.

According to a third aspect, in the second aspect, a retainer bolt for supporting one end of the cam spring is provided, and a relief valve is incorporated in the retainer bolt.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the valve means is provided with a feedback pin for adjusting a driving pressure of the cam ring guided to the variable displacement mechanism following the cam ring.

[0011]

According to the first aspect of the present invention, by disposing the valve means on the cam ring support orthogonal line Sx,
The sliding amount of the follower of the valve means with respect to the cam ring can be suppressed to a small value, and the operation amount of the valve means linked to the cam ring can be ensured large, and the flow of the working fluid can be controlled accurately.

By arranging the cam spring in the radial direction of the rotor, the sliding amount of the cam spring with respect to the cam ring can be suppressed small, and the cam ring can be smoothly rotated.

By arranging the cam spring in the radial direction of the rotor along with the valve means, it is possible to avoid an increase in the size of the cam ring and the casing for accommodating the cam ring.

In the second aspect of the present invention, the relief valve is opened to release the pressure in the cam pressure chamber, whereby the cam ring moves to the side where the pump discharge flow rate decreases, and the rise in the pump discharge pressure is suppressed. As compared with the conventional structure in which the relief valve is connected to the pump discharge passage, the amount of hydraulic oil flowing through the relief valve is smaller, so that the structure of the valve mechanism of the relief valve is simplified and downsized. As a result, it is possible to arrange the relief valve inside the coiled cam spring, so that the casing for accommodating the vane pump can be made compact, and the processing for inserting the relief valve into the casing is reduced, and the production is reduced. You can enhance the nature.

Further, since the amount of hydraulic oil flowing through the relief valve is small, the relief noise can be reduced, and the rise in oil temperature can be suppressed to reduce wasteful energy consumption.

In the third aspect of the present invention, a relief valve is incorporated in a retainer bolt supporting one end of a cam spring, whereby the number of parts is reduced, the casing for accommodating the vane pump is made compact, and a relief valve for the casing is provided. The number of processes for intervening is small, and the productivity can be increased.

In the fourth aspect of the present invention, by disposing the feedback pin on the cam ring support orthogonal line Sx,
The sliding amount of the feedback pin with respect to the cam ring can be kept small, and the displacement amount of the feedback pin that follows the cam ring is ensured large. As a result, the position of the cam ring can be accurately detected via the feedback pin to control the pump discharge flow rate.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a vane pump provided as a hydraulic pressure source of a power steering device mounted on a vehicle will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the vane pump 1 includes a rotor 50 rotatably housed in a casing 60, a plurality of vanes 24 slidably projecting from the rotor 50, and
The cam ring 70 surrounding each vane 24 is mainly constituted. Each vane 24 slides its outer peripheral end against the inner peripheral surface of the cam ring 70 while moving in and out of the rotating rotor 50 in the radial direction to expand and contract the pump chamber.

The rotation of the rotor 50 is transmitted from the engine, and the rotor 50 rotates counterclockwise as indicated by an arrow in the figure. Hydraulic oil is sucked from a suction port 41 into a pump chamber that expands between the vanes 24 with the rotation of the rotor 50, and each vane 2.
The hydraulic oil is discharged to the discharge port 42 from the pump chamber that contracts between the four. The suction port 41 communicates with the tank 6 via the suction passage 10, and the discharge port 42 is connected to the pump discharge passage 11.
Through a hydraulic cylinder of a power steering device (not shown).

The inner peripheral cam surface of the cam ring 70 is formed to have a substantially circular cross section. As the eccentric amount of the center of the cam ring with respect to the rotor shaft increases, the pump displacement increases, and the pump discharge flow rate increases. When the center of the cam ring is on the rotor axis, the pump discharge flow rate becomes zero.

As a variable displacement mechanism for changing the discharge flow rate of the pump, a cam ring 70 is
1 so as to be rotatable. Further, the cam spring 26 for urging the cam ring 70 to the left is provided. The cam ring 70 is biased by the cam spring 26.
Is moved to the leftmost position, the pump discharge flow rate becomes maximum.

To rotate the cam ring 70 against the cam spring 26, the cam ring 7 is attached to the casing 60.
The first cam pressure chamber 7 and the second cam pressure chamber 8 are defined so as to sandwich 0. As the pressure in the first cam pressure chamber 7 increases with respect to the second cam pressure chamber 8, the cam ring 70 turns to the right against the cam spring 26, and the pump discharge flow rate gradually decreases. The casing 60 is provided with a seal member 22 that is in sliding contact with the outer peripheral surface of the cam ring 70, and seals the first cam pressure chamber 7 and the second cam pressure chamber 8, respectively.

The first cam pressure chamber 7 communicates with the discharge port 42 via the discharge pressure introduction passage 12, and a damping orifice 112 is provided in the discharge pressure introduction passage 12.

The second cam pressure chamber 8 communicates with the discharge port 42 via the discharge pressure introducing passage 13 and the return passage 1
5 communicates with the tank 6 via the control valve 2 described below. A damping orifice 113 is provided in the discharge pressure introduction passage 13.
Is provided, and a damping orifice 115 is provided in the middle of the return passage 15.

As valve means for controlling the flow of the working fluid,
The control valve 2 for controlling the driving pressure of the cam ring 70 guided to the variable displacement mechanism is provided. The control valve 2 includes a casing 6
0, a spool 80 slidably fitted in the valve hole 65, a valve spring 89 for urging the spool 80 leftward in the drawing, and a feedback pin for following the cam spring 26. 90 and the like.

A first spool pressure chamber 17 is defined between the valve hole 65 and the left end of the spool 80. The first spool pressure chamber 17 communicates with the discharge port 42 via the passage 19, and a damping orifice 119 is interposed in the passage 19.

A second spool pressure chamber 18 is defined between the valve hole 65 and the right end of the spool 80. The second spool pressure chamber 18 is interposed in the pump discharge passage 11. A flow detection orifice 62 is interposed in the pump discharge passage 11 upstream of the second spool pressure chamber 18, and a differential pressure across the flow detection orifice 62 in the pump discharge passage 11 acts on both ends of the spool 80. As a result, as the hydraulic oil flow rate in the pump discharge passage 11 increases, the differential pressure across the flow rate detection orifice 62 increases, and the spool 80 moves rightward against the valve spring 89.

The flow detection orifice 62 is
The opening area of the flow detection orifice 62 gradually decreases when the spool 80 moves rightward to decrease the pump discharge flow rate as the pump rotation speed increases.

The spool 80 has a cam position detecting hole 81 for adjusting the driving pressure of the cam ring 70. The cam position detection hole 81 is interposed in the middle of the return passage 15, and the pressure in the second cam pressure chamber 8 is released as the opening area of the cam position detection hole 81 increases, and the cam ring 70 moves rightward. It turns and the pump discharge flow rate decreases.

As shown in FIG. 2, the feedback pin 90 is slidably fitted in the pin hole 82 of the spool 80,
One end of the cam ring 7 is biased by the biasing force of the spring 91.
The cam ring 70 is pressed against the outer peripheral surface of the cam ring 70 and changes the opening area of the cam position detecting hole 81 following the cam ring 70 which rotates.

An annular groove 83 is formed on the outer periphery of the spool 80, and the cam position detecting hole 81 communicates the annular groove 83 with the pin hole 82. A through hole 92 penetrating the feedback pin 90 is formed, and the return passage 15 is defined by the through hole 92, the pin hole 82, the cam position detecting hole 81, the annular groove 83, and the like.

When the pressure in the second cam pressure chamber 8 rises above a predetermined value, a relief valve 30 for releasing the pressure is provided. The relief valve 30 includes a relief port 31 that communicates the second cam pressure chamber 8 with the return passage 15, a ball 32 that opens and closes the relief port 31, and a relief spring 33 that urges the ball 32 in a closing direction. .

The operation of the vane pump 1 configured as described above will be described. While the vane pump 1 is stopped and the pump rotation speed increases to a predetermined value, the spool 80
Is held at a position where the cam position detecting hole 81 is shut off by the urging force of the valve spring 89. This allows
The cam ring 70 is held at the maximum eccentric position, and as shown in FIG. 6, the amount of hydraulic oil flowing through the pump discharge passage 11 increases as the rotation speed of the rotor 50 increases, so The discharge pressure is sufficiently increased, and the hydraulic assist force required for the power steering device can be secured.

When the rotational speed of the pump increases and the differential pressure across the flow detection orifice 62 exceeds a predetermined value, the spool 80 moves against the urging force of the valve spring 89 as shown in FIG.
Is moved to the right to open the cam position detection hole 81 and open the return passage 15, the pressure difference between the front and rear of the flow detection orifice 62 and the valve spring 89.
The opening area of the cam position detecting hole 81 is increased or decreased at a position where the urging force of the cam position is balanced. Accordingly, the position of the cam ring 70 is automatically adjusted to control the pump discharge flow rate, and the flow rate of the hydraulic oil returned from the vane pump 1 to the tank 6 is reduced to reduce wasteful energy consumption.

When the differential pressure across the flow detection orifice 62 rises and the spool 80 is displaced rightward to increase the opening area of the cam position detection hole 81, the pressure (drive pressure) of the second cam pressure chamber 8 decreases. The cam ring 70 moves rightward to reduce the pump discharge flow rate. At this time, if the pressure in the second cam pressure chamber 8 decreases too much, the cam ring 70 rotates rightward, and the feedback pin 90 is pushed rightward to reduce the opening area of the cam position detection hole 81, thereby reducing The pressure in the two-cam pressure chamber 8 is restored, and the cam ring 70 is pushed back to an appropriate position.

Since the opening area of the cam position detecting hole 81 is feedback-controlled by the end of the feedback pin 90 following the cam ring 70 in this manner, the cam ring corresponding to the pressure balance acting on the spool 80 and the position of the cam ring 70 is controlled. The drive pressure of 70 is adjusted, and a pump discharge flow rate characteristic always corresponding to the opening area of the cam position detection hole 81 is obtained. Therefore, even if the operating conditions such as the frictional force acting on the cam ring 70, the internal leakage, and the pump discharge pressure change, the desired pump discharge flow rate characteristic can be obtained without shifting the position of the cam ring 70.

When the pump rotation speed rises above a predetermined value, the spool 80 reduces the opening area of the flow rate detection orifice 62, and the pump discharge flow rate gradually decreases as the pump rotation speed increases. This prevents the pump discharge amount from becoming excessive during high-speed running of the vehicle in which the assist force required for the power steering device is reduced.

Since the opening area of the flow rate detection orifice 62 is adjusted by the spool 80 for controlling the pump discharge flow rate, inclusions in this control system are eliminated to improve control responsiveness and control stability. The target flow rate can be secured. On the other hand, in the conventional structure in which the opening area of the flow detection orifice is adjusted according to the position of the cam ring, if the position of the cam ring shifts for some reason, the position of the cam ring further increases as the position of the spool shifts. It changes and the control system becomes unstable.

When the spool 80 is displaced rightward in FIG. 1 to enlarge the area of the cam position detecting hole 81, the damping orifice 115 interposed in the return passage 15 flows out through the cam position detecting hole 81. By providing resistance to the flowing hydraulic oil flow, the cam ring 70
Excessive rightward movement following the zero displacement is suppressed, and the position control of the cam ring 70 is stabilized.

Incidentally, each pump chamber partitioned by the vanes 24 between the cam ring 70 and the rotor 50 has:
Although the pump discharge pressure and the pump suction pressure are generated alternately with the rotation of the rotor 50, the number of pump chambers where the pump discharge pressure is generated and the number of pump chambers where the pump suction pressure is generated differ depending on the rotation position of the rotor 50. A vibration force acts on the cam ring 70 due to the pressure fluctuation of the pump chamber. In response to this, the damping orifice 119 imparts resistance to the hydraulic oil flowing in and out of the first spool pressure chamber 17, whereby
When the spool 80 is about to be displaced by the exciting force acting on the cam ring 70, the pressures in the first spool pressure chamber 17 and the second spool pressure chamber 18 rise sharply, and the vibration of the spool 80 and the cam ring 70 is suppressed. Generation of vibration, noise, and the like can be prevented.

When the pump discharge pressure rises above a predetermined value, the relief valve 30 opens to release the pressure of the second cam pressure chamber 8, whereby the cam ring 70 rotates rightward in FIG. An increase in the discharge pressure is suppressed.

Next, a specific structure of the above-described vane pump 1 will be described with reference to FIGS.

As shown in FIG. 4, a side plate 61 and an adapter ring 63 are stacked and accommodated in a substantially circular recess formed in the casing 60. Adapter ring 6
An annular cam ring 70 is rotatably supported on the inner side of the support member 3 via a support pin 71. The open end of the casing 60 is closed by a cover 64. The side surfaces of the adapter ring 63, the cam ring 70, and the rotor 50 abut on the cover 64 and are sealed.

The drive shaft 25 is rotatably supported via the metal bearings 76 and 77 over the casing 60 and the cover 64. The rotor 50 is coupled with the drive shaft 25 halfway,
The rotation from the engine is transmitted through the drive shaft 25, the pulley 27, a belt (not shown), and the like.

A plurality of notches 52 extending in the radial direction are formed in the rotor 50 at predetermined intervals, and the vanes 24 are slidably interposed in each notch 52. When the rotor 50 rotates, the tip of the vane 24 extending from the notch 52 comes into contact with the inner peripheral cam surface of the cam ring 70, and a plurality of pump chambers are defined between the vanes 24.

In the side plate 61, a suction port 41 and a discharge port 42 which open to face each pump chamber are formed at symmetrical positions with respect to the drive shaft 25. Also, cover 6
4 is located at a position facing the discharge port 42 and the suction port 41 on the side plate 61 side with the rotor 50 interposed therebetween.
A high-pressure groove 43 and a low-pressure groove 44 are formed.

As shown in FIG. 4, the discharge passage 11 connected to the discharge port 42 is provided with a groove 6 formed in the casing 60.
6, through holes 67 and 68, valve holes 65 and through holes 69, a connector 78 screwed to the casing 60, and the like.

The suction passage 10 for guiding the hydraulic oil from the tank 6 to the suction port 41 includes a groove 72 formed in the cover 64,
The passage 73 is defined by a connector 74 attached to the cover 64 and the like.

As shown in FIG. 5, a retainer bolt 55 screwed to the casing 60 is provided.
A valve spring 89 is interposed between the spool 5 and the spool 5.

The feedback pin 90 is arranged in the radial direction of the rotor 50, and its tip is
And abuts on the outer peripheral side of the cam ring 70.

The plane connecting the axis O p of the support pin 71 and the axis O c of the cam ring 70, which is the pivot of the cam ring 70, is defined as a cam ring center plane Sy.
When a straight line orthogonal to y and intersecting with the axis Or of the rotor 50 is defined as a cam ring support orthogonal line Sx, the feedback pin 90 of the control valve 2 is arranged such that its axis Of is on the cam ring support orthogonal line Sx.

A spring receiving hole 57 for receiving the coiled cam spring 26 is formed in the casing 60.
A retainer bolt 56 screwed into the spring receiving hole 57 is provided. The cam spring 26 is interposed between the retainer bolt 56 and the cam ring 70.

The cam spring 26 is arranged in the radial direction of the rotor 50 along with the feedback pin 90.
That is, the cam spring 26 is arranged so that the coil center line Os of the cam spring 26 and the center line Of of the feedback pin 90 intersect on the axis Or of the rotor 50. As a result, the coil center line Os of the cam spring 26 approaches the diagonal line of the casing 60, and the retainer bolt 56 supporting the cam spring 26 is disposed at the corner of the casing 60.

The portion of the cam ring 70 where one end of the cam spring 26 abuts is formed in a plane perpendicular to the coil center line Os of the cam spring 26.

The relief valve 30 is disposed inside the coiled cam spring 26 and is incorporated in a retainer bolt 56. The retainer bolt 56 has a valve receiving hole 58 for receiving the relief valve 30, and a valve seat 59 is fitted into the valve receiving hole 58. The relief port 31 is opened in the valve seat 59, and the ball 32 is seated thereon.

Return path 1 connected to relief port 31
5 is a valve receiving hole 58, a through hole 4 of a retainer bolt 56.
5, an annular passage 46 defined between a spring receiving hole 57 and a retainer bolt 56, a through hole 47 of a casing 60,
It is defined by an annular groove 83 and the like.

Next, the operation of the embodiment of the present invention configured as described above will be described.

By arranging the feedback pin 90 on the cam ring support orthogonal line Sx, the sliding amount of the feedback pin 90 with respect to the cam ring 70 can be suppressed small, and the cam spring 26 can be smoothly rotated.

Further, a large displacement amount of the feedback pin 90 following the cam ring 70 can be secured, and the position of the cam ring 70 can be accurately detected. That is, by increasing the amount of change in the opening area of the cam position detection hole 81 by the feedback pin 90, the control accuracy of the pump discharge flow rate can be increased.

By arranging the cam spring 26 in the radial direction of the rotor 50 alongside the feedback pin 90, it is not necessary to form a projection or the like for receiving the cam spring 26 on the cam ring 70, so that the casing 60 can be prevented from being enlarged. Further, when the coil center line Os of the cam spring 26 is brought closer to the diagonal line of the casing 60, the retainer bolt 5 supporting the cam spring 26 is formed.
The large protrusion of the casing 6 from the casing 60 is suppressed, and an increase in the size of the casing 60 can be avoided.

By arranging the cam spring 26 in the radial direction of the rotor 50, the sliding amount of the cam spring 26 with respect to the cam ring 70 can be reduced, and the cam spring 26 can be smoothly rotated.

When the relief valve 30 is opened to release the pressure in the second cam pressure chamber 8, an increase in the pump discharge pressure is suppressed. Compared with the conventional structure in which the relief valve is connected to the pump discharge passage, the relief valve 30 connected to the second cam pressure chamber 8 has a small amount of hydraulic oil flowing through the relief valve 30. Therefore, the structure of the valve mechanism is simplified. Downsizing is achieved. As a result, it is possible to arrange the relief valve 30 inside the coiled cam spring 26 and to incorporate the relief valve 30 into the retainer bolt 56, so that the casing 60 can be made compact and the relief valve 30 for the casing 60 is interposed. Requires less processing.

Furthermore, since the amount of hydraulic oil flowing through the relief valve 30 is small, the relief noise can be reduced, and the rise in oil temperature can be suppressed to reduce unnecessary energy consumption.

As another embodiment, a pair of cam springs may be provided, and each cam spring may be arranged in the radial direction of the rotor so as to sandwich the control valve. In this case, the length of each cam spring is shortened to further reduce the size.

Further, as a valve means for controlling the flow of the working fluid, a variable orifice for changing the size of a throttle provided in the pump discharge passage following the rotating cam ring may be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a vane pump according to an embodiment of the present invention.

FIG. 2 is a sectional view of a spool and the like.

FIG. 3 is a front view of the vane pump.

FIG. 4 is a sectional view taken along the line AA of FIG. 3;

FIG. 5 is a sectional view taken along the line BB in FIG. 3;

FIG. 6 is a characteristic diagram showing a relationship between a pump rotation speed and a pump discharge flow rate.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 vane pump 2 control valve 7 first cam pressure chamber 8 second cam pressure chamber 24 vane 26 cam spring 30 relief valve 50 rotor 60 casing 62 flow detection orifice 65 valve hole 70 cam ring 80 spool 81 cam position detection hole 90 feedback pin

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Yakabe 2-4-1 Hamamatsucho, Minato-ku, Tokyo World Trade Center Building Kayaba Industry Co., Ltd. F term (reference) 3H044 AA02 BB05 BB08 CC00 CC08 CC11 CC13 CC14 CC16 CC18 CC19 CC21 CC27 DD10 DD11 DD24 DD27 DD28 DD35

Claims (4)

[Claims] A plurality of vanes slidably protruding from a rotating rotor; a cam ring defining a pump chamber by sliding an outer peripheral end of each of the vanes; and a variable displacement mechanism for rotating the cam ring. A valve means for controlling the flow of the working fluid in conjunction with the rotation of the cam ring; and a cam spring for urging the cam ring in a rotation direction. When a plane connecting the rotation fulcrum Op and the axis Oc of the cam ring is a cam ring center plane Sy, and a straight line orthogonal to the cam ring support center plane Sy and intersecting with the rotor axis Or is a cam ring support orthogonal line Sx, The valve means is arranged on the cam ring support orthogonal line Sx, and the cam spring is arranged in the radial direction of the rotor along with the valve means. Variable displacement vane pump according to claim. 2. A cam pressure chamber, which contracts as the cam ring rotates to the side where the pump discharge flow rate decreases, around the cam ring, and a driving pressure of the cam ring guided to the cam pressure chamber. 2. The variable displacement vane pump according to claim 1, further comprising a relief valve that releases a driving pressure of the cam pressure chamber when the pressure rises above a predetermined value, wherein the relief valve is disposed inside the cam spring. 3. 3. The variable displacement vane pump according to claim 2, further comprising a retainer bolt for supporting one end of the cam spring, wherein the retainer bolt includes the relief valve. 4. The valve means according to claim 1, wherein said valve means has a feedback pin for adjusting a driving pressure of said cam ring guided to said variable displacement mechanism following said cam ring. The variable displacement vane pump according to the above.