JP4240308B2 - Vane pump - Google Patents

Description

  The present invention relates to a vane pump applied to a vehicle or the like.

The vane pump includes a cam ring having a cam surface on an inner peripheral surface, a rotor that rotates within the cam ring, and a plurality of vanes that are inserted into a plurality of vane storage grooves provided on the outer periphery of the rotor, and the rotor rotates. Then, the suction pump chamber and the discharge pump chamber are defined in a space surrounded by the cam surface, the outer periphery of the rotor and the vane by moving each vane radially outward by generation of centrifugal force and sliding on the cam surface. The pump action is performed when the volume changes.
The vane pump has a small centrifugal force acting on the vane in the low-rotation region of the pump, so the pressing force required to prevent the vane from moving away from the cam surface (hereinafter referred to as the required pressing force) does not occur on the vane, and the pump discharge capacity is reduced. It's easy to do.

  Therefore, a back pressure chamber is provided at the bottom of the vane housing groove, and a constant back pressure is supplied to the back pressure chamber from the beginning of rotation of the vane pump to generate a pressing force due to the back pressure on the vane. There is a conventional technique for preventing the deterioration of the above. However, the conventional technology is generated from the pressing force (see FIG. 5B) generated in the vane by the action of the centrifugal force that increases with the increase in the rotation speed of the vane pump and the initial rotation (idling state of the rotation speed idle). As shown in FIG. 5 (c), the vane does not move away from the cam surface when the number of rotations of the vane pump increases. Since the total pressing force that greatly exceeds the required pressing force acts on the cam surface, the PV limit value will be exceeded even in the high rotation range of the pump, and the durability of the vane will be reduced, or in the high rotation range There is a risk that the fuel consumption will deteriorate.

Therefore, a vane pump described in Patent Document 1 is known as a solution to this problem. In this patent document 1, a sensor that detects the rotational speed of a rotor, an electromagnetic valve that controls supply of back pressure to a vane, and a control unit are provided, and a constant back pressure is supplied in a low-rotation region of the pump. When the sensor detects a predetermined number of rotor revolutions that can generate the required pressing force only by the centrifugal force of the vane, the control unit is Control to stop the supply of pressure is performed. This suppresses an excessive pressing force in the high rotation region of the pump, prevents a decrease in vane durability, and prevents a deterioration in fuel consumption in the high rotation region.
Japanese Patent Laid-Open No. 05-157058

  However, in Patent Document 1, as shown in FIG. 6 (a), a pressing force by a constant back pressure is applied up to a reference rotational speed Na that can generate a required pressing force only by the centrifugal force of the vane. And, just before the solenoid valve stops the supply of back pressure, as shown by the hatched area in FIG. 6 (c), an excessive pressing force is generated relative to the required pressing force and acts on the cam surface. The friction on the vane and the cam surface is increased, which may cause a deterioration in fuel consumption.

Moreover, in patent document 1, since a sensor, a solenoid valve, and a control part are used, there exists a problem that control becomes complicated.
Therefore, the present invention has been made in view of the above circumstances, and not only in a high rotation area of the pump but also in a rotation area of the pump in which a force pressing the vane against the cam surface can be applied only by centrifugal force. A first object is to provide a vane pump that can improve the fuel consumption by reducing the friction of the sliding portion. Furthermore, it is a second object to provide a vane pump that can simplify back pressure control.

The vane pump according to the present invention includes a cam ring provided with a cam surface on the inner periphery, a rotor rotating within the cam ring, and a plurality of vane storage grooves provided on the outer periphery of the rotor, and centrifugal force generated by the rotation of the rotor. A plurality of vanes that move radially outward by the action of the above and slide on the cam surface, and are defined by a space surrounded by the cam surface, the outer periphery of the rotor, and the plurality of vanes. In a vane pump having a pump chamber whose volume changes, supplying a back pressure to a back pressure chamber provided in the vane storage groove generates a pressing force for pressing the vane against the cam surface. When the rotational speed of the rotor that can generate a pressing force that does not separate from the cam surface only by the action of the centrifugal force is a reference rotor rotational speed, Until the rotational speed of the rotor rises to the reference rotational speed of the rotor, the back pressure supplied to the back pressure chamber is gradually decreased and the pressing force by the back pressure is continuously reduced. A vane back pressure control means is provided , wherein the vane back pressure control means includes a first oil passage to which a discharge pressure of the pump chamber is supplied, and a second oil passage communicating with the first oil passage through a throttle. And a third oil passage communicating with the back pressure chamber, and a pressure reducing valve connected to the first, second and third oil passages, the pressure reducing valve being connected to the second oil passage. The first port communicating, the second port communicating with the back pressure chamber, the drain port, and the discharge pressure supplied to the first oil passage in the direction in which the drain port communicates with the second port acts. And a second pressure receiving surface on which the back pressure of the back pressure chamber acts via the third oil passage. And a valve spool having the same area as the first pressure receiving surface and having a third pressure receiving surface on which the hydraulic pressure of the second oil passage acts in a direction in which the first port and the second port communicate with each other. with a vane pump, characterized in that said first port and said second port is provided with a return spring which gives a biasing force to the valve spool in a direction that communicates.

  According to the present invention, the vane back pressure control means is configured to reduce the vane until the rotational speed of the rotor is increased to the reference rotor rotational speed at which the pressing force that does not separate the vane from the cam surface can be generated by the action of centrifugal force. Since the back pressure that generates the pressing force to press against the cam surface is gradually decreased to continuously reduce the pressing force due to the back pressure, the cam surface is always excessive even if the rotor speed increases. The pressing force is suppressed from acting. Thereby, friction of sliding parts, such as a vane and a cam surface, falls, and it can aim at improvement in fuel consumption.

Hereinafter, embodiments of the vane pump of the present invention will be described with reference to the drawings.
FIG. 1A and FIG. 1B are schematic configuration diagrams showing a first embodiment according to the present invention.
The vane pump 2 of the present embodiment includes a cam ring 6 having a cam surface 4 on the inner periphery, a rotor 8 that rotates within the cam ring 6, a vane storage groove 10 provided on the outer periphery of the rotor 8, and the vane storage groove 10. The vane 12 that is inserted into the pipe and is movable radially outward (upward in FIG. 1B) is accommodated in a pump cover and a pump housing (not shown). A plurality of vane storage grooves 10 are provided across the entire outer periphery of the rotor 8 with a predetermined interval, and a plurality of vanes 12 are inserted into the respective vane storage grooves 10. Then, each vane 12 to which centrifugal force is applied by the rotation of the rotor 8 moves radially outward and slides on the cam surface 4, and the space surrounded by the cam surface 4, the outer periphery of the rotor 8, and the plurality of vanes 12. When the volume of the pump chamber defined is changed, the pumping action is performed, the working oil is sucked from the oil pan T through the suction port 13, and the working oil having the discharge pressure P1 is discharged from the discharge port 15.

A back pressure chamber 14 is provided at the bottom of the vane storage groove 10, and the third oil passage 22 of the vane back pressure control device 20 communicates with the back pressure chamber 14. When the back pressure is supplied to the back pressure chamber 14, the vane 12 is pushed radially outward to generate a pressing force against the cam surface 4.
The vane back pressure control device 20 includes a third oil passage 22 that communicates with the back pressure chamber 14, a first oil passage 24 that communicates with the discharge port 15, a first oil passage 24, and a throttle 26. And a pressure reducing valve 30 for reducing the hydraulic pressure of the second oil passage 28.
The first oil passage 24 is supplied with the discharge pressure P1 generated in the discharge pump chamber. The second oil passage 28 is supplied with a line pressure P2 (P2 <P1) that is reduced as the discharge pressure P1 passes through the throttle 26. Further, the back pressure Pb adjusted by the line pressure P <b> 2 passing through the pressure reducing valve 30 is supplied to the third oil passage 22.

  The pressure reducing valve 30 is an internal, external pilot and spring type pressure reducing valve, and a valve spool 32 and a return spring 34 are disposed in a valve housing (not shown). That is, the pressure reducing valve 30 includes a first port 36 communicating with the second oil passage 28, a second port 38 communicating with the back pressure chamber 14 via the third oil passage 22, a drain port 40, and a drain port. The first pressure receiving surface 42 on which the discharge pressure P1 supplied to the first oil passage 24 acts so that the valve spool 32 moves in a direction in which the valve 40 and the second port 38 communicate with each other, and the third oil passage 22 communicate with each other. The second pressure receiving surface 47 on which the back pressure acts via the return oil passage 44 and the same area as the first pressure receiving surface 42 and in the direction in which the second port 38 and the first port 36 communicate with each other And a third pressure receiving surface 46 on which the line pressure P2 of the second oil passage 28 acts so that the second oil passage 28 moves, and the return spring 34 has a valve in a direction in which the first port 36 and the second port 38 communicate with each other. Energizing force on spool 32 Eteiru.

Here, the balance type of the pressure reducing valve 30 configured as described above is that the hydraulic pressure before and after the throttle 26 is P1 (discharge pressure), P2 (line pressure: P2 <P1), the spring force of the return spring 34 is F _SP , and the back pressure is When Pb, the pressure receiving area of the first pressure receiving surface 42 and the third pressure receiving surface is A1, and the pressure receiving area of the second pressure receiving surface 47 is A2,
A1 × P1 + A2 × Pb = F _SP + A1 × P2 (1)

Organizing this equation (1)
A1 × (P1-P2) + A2 × Pb = F SP ...... the equation (2).
When the differential pressure (P1−P2) before and after the diaphragm 26 is ΔP, the equation (2) is
A1 × ΔP + A2 × Pb = F _SP (3)

Here, the relationship between the flow rate Q flowing through the throttle 26 and the differential pressure ΔP is:
Q = c × A _ORF √ (2 / ρ × ΔP) (4) In addition, c is a flow coefficient, A _ORF is an orifice sectional area, and ρ is a fluid density.
When this equation (4) is obtained for the differential pressure ΔP,
ΔP = Q ² × ρ / (2 × c ² × A _ORF ² ) (5)

Substituting equation (5) into equation (3) for the back pressure Pb,
Pb = (F _SP / A2) − ((A1 × ρ) / (2 × c ² × A _ORF ² × A2))
× Q ² …… (6)
From this equation (6), it can be seen that the back pressure Pb gradually decreases in a quadratic curve as the flow rate Q increases.
Since the flow rate Q is proportional to the rotational speed of the vane pump 2, the vane back pressure control device 20 according to the present embodiment increases the back pressure as the rotational speed of the vane pump 2 (the rotational speed of the rotor 8) increases. Control is performed to gradually decrease Pb.

Next, operation | movement of the vane back pressure control apparatus 20 of this embodiment is demonstrated, referring FIG.1 and FIG.2.
In the vane back pressure control device 20 of the present embodiment, in the initial rotation of the vane pump 2 (idling state at the rotational speed idle), the pressure difference ΔP before and after the throttle 26 hardly occurs, and the discharge pressure P1 and the line pressure P2 are substantially equal. Since it acts on the first pressure receiving surface 42 and the third pressure receiving surface 46 having the same value and the same area, the first port 36 and the second port 38 are completely in communication with each other by the spring force F _SP of the return spring 34. The valve spool 32 moves so that As a result, at the low rotation speed idle of the vane pump 2, the discharge pressure P1 that has passed through the first port 36 and the second port 38 is supplied to the back pressure chamber 14, and as shown in FIG. A pressing force by the back pressure Pb having the same value is generated in the vane 12.

As the rotational speed of the vane pump 2 increases, the flow rate Q of the discharge pressure P1 flowing into the first oil passage 24 gradually increases, the differential pressure ΔP before and after the throttle 26 increases, and the line pressure P2 The discharge pressure P <b> 1 that is a large value acts on the first pressure receiving surface 42. Since the force acting on the first pressure receiving surface 42 and the force acting on the second pressure receiving surface 47 are the forces that oppose the spring force F _SP of the return spring 34 and the force acting on the third pressure receiving surface 46 , the valve The spool 32 moves, the communication path between the first port 36 and the second port 38 gradually narrows, and the second port 38 and the drain port 40 gradually communicate with each other. As a result, the value of the back pressure Pb gradually decreases, and as shown in FIG. 2A, the pressing force of the vane 12 by the back pressure Pb also gradually decreases.

When the vane pump 2 reaches a predetermined rotational speed Na (the rotational speed at which the necessary pressing force can be generated only by the centrifugal force of the vane 12: the reference rotor rotational speed), the flow rate Q further increases and the throttle is reduced. The pressure ΔP around 26 is increased, and the force that the discharge pressure P1 acts on the first pressure receiving surface 42 and the force that acts on the second pressure receiving surface 47 by the back pressure Pb compress the return spring 34 and compress the valve spool. 32, the communication path of the first port 36 and the second port 38 is completely closed, and the second port 38 and the drain port 40 are completely in communication with each other, and the back pressure Pb to the back pressure chamber 14 is reached. Stop supplying. As a result, as shown in FIG. 2 (a), the pressing force of the vane 12 by the back pressure Pb does not occur at a predetermined rotation speed Na.

  In addition, as shown in FIG. 2B, in the initial rotation of the vane pump 2 (idling state at a low rotational speed idle), a pressing force of the vane 12 is generated by a small centrifugal force acting on the vane 12. As the rotational speed of the vane pump 2 increases, the pressing force of the vane 12 due to centrifugal force increases. When the rotational speed reaches a predetermined rotational speed Na, the necessary pressing force is generated only by the centrifugal force of the vane 12.

  As shown in FIG. 2 (c), at the initial stage of rotation of the vane pump 2, the vane 12 is caused to come into contact with the cam surface 4 by a back pressure Pb having the same value as the discharge pressure P1 and a small centrifugal force generated at a low rotational speed idle. Total pressing force that does not leave As the rotational speed of the vane pump 2 increases, the pressing force of the vane 12 due to the back pressure Pb gradually decreases. Therefore, even if the pressing force of the vane 12 due to the centrifugal force increases, the total pressing force is very large. Don't be. When the vane pump 2 reaches a predetermined rotational speed Na, the pressing force of the vane 12 due to the back pressure Pb is not generated, and the total pressing force that does not separate from the cam surface 4 is only generated by the centrifugal force generated in the vane 12. appear.

Therefore, this embodiment has the following effects.
(A) The vane back pressure control device 20 of the present embodiment supplies the discharge pressure P1 generated in the discharge pump chamber as the back pressure Pb at the initial rotation of the vane pump 2, and the back pressure Pb and the rotation at the initial rotation are generated. With the small centrifugal force that is generated, the vane 12 generates a pressing force that is necessary to prevent the cam surface 4 from being separated from the cam surface 4, so that it is possible to prevent a decrease in discharge capability in the low rotation region of the vane pump 2.

(B) The vane back pressure control device 20 of the present embodiment increases the back pressure Pb as the pressing force generated in the vane 12 increases due to the centrifugal force accompanying the increase in the rotation speed of the vane pump 2. When the required pressing force is generated only by the centrifugal force generated in the vane 12, the supply of the back pressure Pb to the back pressure chamber 14 is stopped. Therefore, the excessive pressing force indicated by the hatched portion in FIG. 2C does not occur not only in the high rotation region of the vane pump 2 but also in the low rotation region, particularly in the region of the predetermined rotation speed Na or less (in the conventional apparatus of FIG. 6). It is possible to prevent excessive pressing force from acting on the cam surface 4 at all times and to reduce friction of the sliding portions such as the vane 12 and the cam surface 4. Let It is possible to improve the fuel efficiency (corresponding to claim 1).

(C) The vane back pressure control device 20 of the present embodiment indicates that the flow rate Q of the discharge pressure P1 increases as the rotational speed of the vane pump 2 increases, and the differential pressure ΔP before and after the throttle increases as the flow rate Q increases. Control using the throttle 26 and the pressure reducing valve 30 that operates by the pressure difference before and after the throttle 26, and gradually lowering the value of the back pressure Pb acting on the back pressure chamber 14 as the flow rate Q increases. Therefore, it is possible to simplify the control and reduce the cost of the back pressure control device ( corresponding to claim 1 ) as compared with a conventional device using a sensor, a solenoid valve, and a control unit. .

Next, FIG.3 and FIG.4 is a figure which shows a reference example . In addition, the same code | symbol is attached | subjected to the component same as the structure shown in FIG. 1, and the description is abbreviate | omitted.
FIG. 3 is a schematic configuration diagram illustrating a back pressure control device for a vane pump according to a second embodiment, and FIG. 4 is a cross-sectional view of the vane pump 2 in a direction along a drive shaft 50 that rotationally drives the rotor.
In the present embodiment, as shown in FIG. 4, the cam ring 6 is housed in the housing 52, and the side plate 54 is disposed on the side of the cam ring 6 and the rotor 8 that rotates in the cam ring. The side plate 54 is provided with a third oil passage 22 communicating with the back pressure chamber 14 and a first oil passage 24 communicating with the discharge pump chamber (not shown).

A first valve body 56 is rotatably connected to the housing 52. A second valve body 58 is integrally fixed to a side portion of the first valve body 56, and the first and second valve bodies 56 and 58 are configured to rotate synchronously with the drive shaft 50 described above.
The vane back pressure control device 48 of the present embodiment is disposed in the second valve body 58 in the radial direction with respect to the drive shaft 50, and the oil passage 56 a provided in the third oil passage 22 and the first valve body 56 described above. And a pressure reducing valve 60 connected via an oil passage 56b provided in the first oil passage 24 and the first valve body 56.

  The pressure reducing valve 60 is an internal, external pilot and spring type pressure reducing valve, and a valve spool 62 and a return spring 64 are disposed in a valve housing (not shown). That is, the pressure reducing valve 60 includes a first port 66 that communicates with the first oil passage 24, a second port 68 that communicates with the back pressure chamber 14 via the third oil passage 22, a drain port 70, and a second port. A fourth pressure receiving surface 74 on which a back pressure acts is provided via a return oil passage 72 communicating with the third oil passage 22 so that the valve spool 62 moves in a direction in which the port 68 and the drain port 70 communicate with each other. The return spring 64 applies a biasing force to the valve spool 62 in the direction in which the first port 66 and the second port 68 communicate with each other, and when the centrifugal force increases as the pressure reducing valve 60 rotates, the valve spool It arrange | positions so that the urging | biasing force with respect to 62 may become large gradually.

Here, the balance formula of the pressure reducing valve 60 having the above-described configuration is that the weight of the pressure reducing valve 60 is m, the distance from the center of the drive shaft 50 to the center of gravity of the pressure reducing valve 60 is R, the angular velocity of the rotating pressure reducing valve 60 is ω, When the spring force of the return spring 34 is F _SP , the back pressure is Pb, and the pressure receiving area of the fourth pressure receiving surface 74 is A,
m × R × ω ² + A × Pb = F _SP (7)
When this equation (7) is obtained for the back pressure Pb,
Pb = (F _SP −m × R × ω ² ) / A
= (F _SP / A) − ((m × R) / A) × ω ² (8)

From this equation (8), it can be seen that the back pressure Pb gradually decreases as the angular velocity ω increases.
Since the angular velocity ω is proportional to the rotational speed of the vane pump 2, the vane back pressure control device 48 according to the present embodiment also increases the back pressure as the rotational speed of the vane pump 2 (the rotational speed of the rotor 8) increases. Control is performed to gradually decrease Pb.

Next, the operation of the vane back pressure control device 48 of the present embodiment will be described with reference to FIGS. 3 and 4.
In the vane back pressure control device 48 of the present embodiment, since the force for compressing the return spring 64 due to the centrifugal force of the rotating pressure reducing valve 60 hardly acts at the initial stage of rotation of the vane pump 2, the spring force F _SP of the return spring 64 is used. The valve spool 62 moves so that the first port 66 and the second port 68 are in a completely communicated state. Thereby, at the initial rotation of the vane pump 2, the discharge pressure P1 that has passed through the first port 36 and the second port 38 is supplied to the back pressure chamber 14, and the pressing force by the back pressure Pb having the same value as the discharge pressure P1 is applied to the vane 12. Occurs.

As the rotational speed of the vane pump 2 increases, the increasing centrifugal force of the pressure reducing valve 60 that rotates at high speed becomes a force that resists the spring force F _SP of the return spring 34. As the spool 62 moves, the communication path between the first port 66 and the second port 68 gradually narrows, and the second port 68 and the drain port 70 gradually communicate with each other. Further, the hydraulic pressure from the third oil passage 22 acting on the fourth pressure receiving surface 74 also decreases. Thereby, since the value of the back pressure Pb gradually decreases, the pressing force of the vane 12 gradually decreases.

  When the vane pump 2 reaches a predetermined rotational speed Na (the rotational speed at which the necessary pressing force can be generated only by the centrifugal force of the vane 12: the reference rotor rotational speed), the return spring is further increased by the increased centrifugal force. Since 64 is compressed and the valve spool 62 moves, the communication path of the first port 66 and the second port 68 is completely closed, and the sixth port 38 and the drain port 70 are completely in communication with each other. Supply of the back pressure Pb to the chamber 14 is stopped. As a result, the pressing force of the vane 12 by the back pressure Pb is not generated at the predetermined rotation speed Na.

  In the initial stage of rotation of the vane pump 2, a total pressing force that prevents the vane 12 from separating from the cam surface 4 is generated by the back pressure Pb having the same value as the discharge pressure P1 and the small centrifugal force generated at the low rotational speed idle. As the rotational speed of the vane pump 2 increases, the pressing force of the vane 12 due to the back pressure Pb gradually decreases. Therefore, even if the pressing force of the vane 12 due to the centrifugal force increases, the total pressing force is very large. Don't be. When the vane pump 2 reaches a predetermined rotational speed Na, the pressing force of the vane 12 due to the back pressure Pb is not generated, and the total pressing force that does not separate from the cam surface 4 is only generated by the centrifugal force generated in the vane 12. appear.

Therefore, this embodiment has the following effects.
(D) The vane back pressure control device 48 according to the present embodiment supplies the discharge pressure P1 generated in the discharge pump chamber as the back pressure Pb in the early stage of rotation of the vane pump 2, and the back pressure Pb is generated in the early stage of rotation. With the small centrifugal force that is generated, the vane 12 generates a pressing force that is necessary to prevent the cam surface 4 from being separated from the cam surface 4, so that it is possible to prevent a decrease in discharge capability in the low rotation region of the vane pump 2.

(E) The vane back pressure control device 48 of the present embodiment increases the back pressure Pb as the pressing force generated in the vane 12 increases due to the action of the centrifugal force accompanying the increase in the rotation speed of the vane pump 2. When the required pressing force is generated only by the centrifugal force generated in the vane 12, the supply of the back pressure Pb to the back pressure chamber 14 is stopped. Therefore, not only the high rotation region of the vane pump 2 but also the low rotation region, particularly the region of the predetermined rotation speed Na or less, the excessive pressing force generated in the conventional apparatus of FIG. Excessive pressing force can be prevented from acting, and the friction of sliding portions such as the vane 12 and the cam surface 4 can be reduced to improve fuel efficiency (corresponding to claim 1).

(F) The vane back pressure control device 48 of the reference example is provided with a return spring 64 that uses the fact that the centrifugal force of the rotating member changes as the rotational speed of the vane pump 2 changes, and the urging force changes as the centrifugal force increases. As the pressure reducing valve 60 is integrated with the drive shaft 50 and the rotational speed of the vane pump 2 increases, the pressure reducing valve 60 gradually increases the value of the back pressure Pb acting on the back pressure chamber 14 by the change in the biasing force of the return spring 64. since control is performed gradually reduced, the sensor, as compared with the conventional apparatus using the electromagnetic valve and the control unit, simplification of control, Ru can be reduced in cost of the back pressure control device.

  The present invention is not limited to the above-described embodiment. For example, an electromagnetic valve is provided between the back pressure chamber 14 and the discharge port 15, and the back pressure is increased up to the rotor rotation speed (rotor reference rotation speed) Na. Even if the solenoid valve is controlled so as to gradually decrease Pb, the same effect can be obtained.

It is a schematic structure figure showing the vane pump of a 1st embodiment concerning the present invention. It is a graph for demonstrating operation | movement of the pane pump of 1st Embodiment. It is a schematic block diagram which shows the pane pump of a reference example . It is the figure which showed the cross section along the drive shaft which rotationally drives the rotor of the vane pump of a reference example . It is a graph for demonstrating operation | movement of the conventional apparatus which is supplying the fixed back pressure irrespective of increase / decrease in pump rotation speed. It is a graph for demonstrating operation | movement of the conventional apparatus which has stopped supply of the back pressure at the time of producing | generating the pressing force which a vane does not separate from a cam surface by the effect | action of a centrifugal force.

Explanation of symbols

2 Vane pump 4 Cam surface 6 Cam ring 8 Rotor 10 Vane storage groove 12 Vane 14 Back pressure chamber 15 Discharge port 20, 48 Vane back pressure control device 22 Third oil passage 24 First oil passage 26 Restriction 28 Second oil passage 30, 60 Pressure reducing valve 32, 62 Valve spool 34, 64 Return spring 36, 66 First port 38, 68 Second port 40, 70 Drain port 42 First pressure receiving surface 44, 72 Return oil passage 46 Third pressure receiving surface 47 Second pressure receiving surface 50 drive shaft 52 housing 56 first valve body 58 second valve body 74 fourth pressure receiving surface F _SP spring force Na rotor speed (reference rotor speed)
P1 Discharge pressure P2 Line pressure Pb Back pressure Q Flow rate ΔP Differential pressure ω Angular velocity

Claims (1)

A cam ring having a cam surface on the inner periphery, a rotor that rotates in the cam ring, and a plurality of vane storage grooves provided on the outer periphery of the rotor. A plurality of vanes that move to slide on the cam surface, and a pump chamber that is defined in a space surrounded by the cam surface, the outer periphery of the rotor, and the plurality of vanes, and whose volume is changed by the rotation of the rotor. In the vane pump
By supplying back pressure to a back pressure chamber provided in the vane storage groove, a pressing force for pressing the vane against the cam surface is generated, and a pressing force that does not separate the vane from the cam surface is generated by the centrifugal force. When the rotation speed of the rotor that can be generated only by the action of force is a reference rotor rotation speed, the rotor is supplied to the back pressure chamber at least until the rotation speed of the rotor rises to the rotor reference rotation speed. A vane back pressure control means is provided for performing control to gradually decrease the back pressure and continuously reduce the pressing force due to the back pressure ,
The vane back pressure control means communicates with a first oil passage to which a discharge pressure of the pump chamber is supplied, a second oil passage communicating with the first oil passage through a throttle, and the back pressure chamber. A third oil passage and a pressure reducing valve connected to the first, second and third oil passages, the pressure reducing valve communicating with the second oil passage, A second pressure port communicating with the back pressure chamber, a drain port, a first pressure receiving surface on which the discharge pressure supplied to the first oil passage acts in a direction in which the drain port communicates with the second port; The second pressure receiving surface on which the back pressure of the back pressure chamber acts via the third oil passage has the same area as the first pressure receiving surface, and the first port and the second port communicate with each other. A valve spool having a third pressure receiving surface on which the oil pressure of the second oil passage acts, and the first port and the front Vane pump second port, characterized in that it comprises a return spring which gives a biasing force to the valve spool in a direction that communicates.

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