JP2009074481A - Control valve of variable displacement vane pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control valve of a variable displacement vane pump capable of preventing abrasion on a spool valve element, and improving reliability. <P>SOLUTION: A third chamber C3 between two streaks of land parts 12A and 12B is communicated with a suction side passage L1, a plurality of opening parts 13 and 13A are provided symmetrically in an outer peripheral direction on a sliding position of the land part 12A partitioning a first chamber C1 and the third chamber C3, and the opening parts 13 and 13A are communicated with a cam ring outer peripheral part (b) on an opposite side of a spring 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control valve for a variable displacement vane pump, and more particularly to an improvement in a control valve that controls flow rate with a variable amount of eccentricity.

For example, an oil pump used for power steering in a vehicle is generally driven by an engine, and at the time of steering, a discharge pressure and a flow rate of a working fluid are required regardless of the number of rotations, and must be dealt with.
In ordinary vane pumps, the discharge capacity per revolution is basically constant, so for the above applications, a valve mechanism is provided on the discharge side to control the flow rate and pressure.

On the other hand, in the variable displacement vane pump as shown in FIG. 2, the amount of eccentricity between the rotor 2 and the cam ring 4 can be changed, and the flow rate is variable.
That is, the rotor 2 is provided with a plurality of grooves in a radial pattern (with a small inclination in the illustrated example), and vanes 3 are inserted into these grooves so as to be slidable in the radial direction. The cam ring 4 is provided eccentric to the drive shaft 1 on the outer side, and the rotor is disposed in a region surrounded by the two vanes 3 and 3 between the outer periphery of the rotor 2 and the inner periphery of the cam ring 4. With the rotation of 2, the working fluid is sucked from the suction side 5 a and is carried to the discharge side 5 b and discharged.

The cam ring 4 is biased by a spring 6 on one side (right side in the figure) and is eccentric with respect to the drive shaft 1. Fluid pressure is introduced into the outer peripheral portion b on the other (left side in the drawing) side of the cam ring 4, and the amount of eccentricity of the cam ring 4 is defined by the balance with the urging force of the spring 6.
Therefore, by controlling the fluid pressure acting on the cam ring 4, the eccentric amount of the cam ring 4 can be changed and the flow rate can be variably controlled.

Next, the path of oil as the working fluid in the variable displacement vane pump will be described.
Oil flowing through the first passage L1 from the oil reservoir 7 is supplied to the suction port c via the control valve 10A. The supplied oil enters the region sandwiched between the vanes 3 and 3 from the groove 5a recessed in the side plate, is carried to the discharge side by the rotation of the rotor 2, and is discharged from the groove 5b of the side plate to the discharge port d. Is done.

The oil discharged from the discharge port d is discharged to a target fluid device, for example, a power steering (not shown) via the second passage L2 in which the orifice 8 is interposed.
On the other hand, in the vicinity of the discharge port d, the third passage L3 branches from the second passage L2, and the third passage L3 communicates with one side (left side in FIG. 2) of the control valve 10A.
Further, in the downstream region of the orifice 8 in the second passage L2, the fourth passage L4 is branched from the second passage L2, and the fourth passage L4 is on the other side of the control valve 10A (in FIG. 2). (Right side).

The control valve 10A is provided with a fifth passage L5, and the fifth passage L5 communicates with a rear surface (cam ring rear surface) b on the opposite side of the cam ring 4 to the spring 6 (left side of the rotor 2 in FIG. 2). .
The amount of eccentricity of the cam ring 4 depends on the pressure of oil supplied from the third passage L3, the pressure of oil supplied from the fourth passage L4, and the pressure of oil supplied from the fifth passage L5. Based on the control.
2 is a sixth passage for communicating the back pressure accompanying the movement of the cam ring 4 to the suction port c.

Next, the control valve 10A will be described with reference to FIG.
A spool valve body 11 is slidably provided inside the control valve 10A, and the spool valve body 11 has two first land portions 12A and 12B protruding from the outer periphery thereof. The control valve 10A is divided into three chambers C1, C2, and C3.

The first chamber C1 (the left chamber in FIG. 3) communicates with the third passage L3 from the discharge port d.
The second chamber C2 (the chamber on the right side in FIG. 3) communicates with the fourth passage L4 from the downstream of the orifice 8. A spring 15 is inserted into the second chamber C2, and the spring 15 biases the valve body 11 toward the first chamber C1 (the left side in FIG. 3).
The third chamber C3 located between the first land portion 12A and the second land portion 12B communicates with the first passage L1 on the suction side.

A fifth passage L5 communicating with the rear surface b of the cam ring 6 is opened in the vicinity of the first land portion 12A that divides the first chamber C1 and the third chamber C3.
In FIG. 3, reference numeral 14 denotes a “blur hole” formed in an extension portion of the fifth passage L5 when the fifth passage L5 is drilled. This blind hole 14 is drilled in order to adjust the balance of the valve body 11 by the oil pressure.

In FIG. 2, a ball valve 16 is inserted into the spool valve body 11 as a pressure adjusting mechanism, and a communication hole 17 is formed. The ball valve 16 is disposed so as to close the communication hole 17 (the ball valve 16 is configured to be normally closed).
When the discharge pressure increases and the discharge pressure in the second chamber C2 (FIG. 3) becomes equal to or higher than the predetermined pressure, the ball valve 16 is opened, and the oil in the second chamber C2 flows through the communication hole. It communicates with the first passage L1 via 17 (FIG. 2). That is, when the ball valve 16 is opened, a part of the discharge flow rate of the second passage L2 is returned to the first passage L1 on the suction side via the second chamber C2, the communication hole 17, and the ball valve 16. It is.

When the ball valve 16 is opened and a part of the discharge flow rate in the second passage L2 is returned to the first passage L1, the pressure in the first chamber C1 is higher than the pressure in the second chamber C2 in FIG. Thus, the spool valve body 11 is moved against the spring 15 to the second chamber C2 side (right direction in FIGS. 2 and 3).
As apparent from FIG. 3, as a result of the spool valve element 11 moving to the second chamber C2 side (rightward in FIGS. 2 and 3), the fifth land L5 is blocked by the first land portion 12A. And the amount of oil flowing through the fifth passage L5 increases.

In FIG. 2, if the amount of oil flowing through the fifth passage L5 increases, the amount of oil supplied to the cam ring back surface b also increases, and the cam ring 4 is in a direction in which the pump capacity decreases (rightward in FIG. 2). Moving. As a result, the discharge pressure is controlled to be equal to or lower than a certain pressure, and thus the discharge pressure is adjusted.
FIG. 4 shows the relationship between the controlled discharge pressure and flow rate.

Next, the flow rate control mechanism will be described.
The discharge pressure acts on the first chamber C1 via the third passage L3, but the pressure acting on the second chamber C2 is equal to the pressure loss due to the orifice 8 interposed in the fourth passage L4. The pressure is lower than the pressure (discharge pressure) acting on the first chamber C1.
When the pump discharge flow rate increases and the pump discharge pressure increases, the pressure loss due to the orifice 8 also increases, and the pressure difference between the pressure acting on the first chamber C1 and the pressure acting on the second chamber C2 (pressure loss due to the orifice 8). The spool valve element 11 moves to the second chamber C2 side (rightward in FIGS. 2 and 3).

As a result of the spool valve body 11 moving toward the second chamber C2 (rightward in FIGS. 2 and 3), the amount of oil flowing through the fifth passage L5 increases, and the amount of oil supplied to the cam ring back surface b is also increased. As a result, the cam ring 4 moves in the direction of decreasing the pump capacity (rightward in FIG. 2). As a result, the discharge flow rate is controlled to be constant.
FIG. 5 shows the relationship of the flow rate controlled with respect to the rotation speed.

On the other hand, when the discharge flow rate of the pump decreases, the discharge pressure also decreases and the pressure difference before and after the orifice 8 decreases. As a result, the biasing force of the spring 15 overcomes the pressure difference between the pressure acting on the second chamber C2 and the pressure acting on the first chamber C1, and the spool valve body 11 moves toward the first chamber C1 (FIGS. 2 and 2). 3 in the left direction).
In FIG. 3, if the spool valve body 11 moves in the direction of the first chamber C1 (leftward in FIG. 3), the area where the fifth passage L5 is blocked by the first land portion 12A increases, and the first chamber C1. The amount of oil flowing from the first to the fifth passage L5 decreases.
In FIG. 2, if the amount of oil flowing to the fifth passage L5 decreases, the cam ring 4 moves in the direction of increasing eccentricity (rightward in FIG. 2) by the biasing force of the spring 6, so that the pump discharge flow rate is It will increase.

In the control valve of the variable displacement vane pump described above with reference to FIGS. 2 and 3, a high pump discharge pressure is applied to the first chamber C1 side of the spool valve body 11, and the pump discharge pressure It also acts on the blind hole 14. On the other hand, since the opening part (opening part to the 5th channel | path L5) shown with the code | symbol 13 in FIG. 3 is connected to the 5th channel | path L5, pressure is comparatively low.
That is, the pressure acting on the blind hole 14 is higher than the pressure in the opening 13, and due to the pressure difference, in FIG. 3, the spool valve body 11 is moved downward in the vertical direction in FIG. 3. A pressing force is applied.

Since the diameter of the opening 13 is larger than the width dimension of the first land 12A (the horizontal dimension in FIG. 3), when the land 12A does not close the opening 13 (when opening), Oil leaks from the first chamber C1 to the third chamber C3 via the opening 13.
As a result, the pressure in the opening 13 becomes low by the amount of the leak, and the differential pressure from the blind hole 14 side (above the spool valve body 11 in FIG. 3) increases.

  Accordingly, the force that presses the spool valve body 11 downward in FIG. 3 increases, and when the control valve is operated frequently, the spool valve body 11 frequently moves in the left-right direction in FIG. 3 while being pressed downward. Will be repeated, causing wear and shortening the service life. Or, malfunction due to a so-called “stick” occurs.

When the blind hole 14 is not provided at the position opposite to the opening 13, the spool body 11 is opposite to the opening 13 due to the flow of oil from the first chamber C 1 to the opening 13 (in FIG. 3). , Move upward in the vertical direction.
For this reason, the opposite side of the spool body 11 to the opening 13 of the first land portion 12A is worn.

Patent Documents 1 and 2 are disclosed as conventional techniques related to a variable displacement vane pump. However, these documents do not disclose any technology that solves the above-described problems or suggests a solution.
JP 2000-161249 A JP 2004-218529 A

  The present invention has been proposed to address the above-described problems, and in a control valve that controls the amount of eccentricity of a variable displacement vane pump, a variable that prevents wear on the spool valve body and improves reliability. The purpose is to provide a control valve for a displacement vane pump.

  The control valve of the variable displacement vane pump according to the present invention is a rotor (having a plurality of vanes 3 slidably radiated therein) inside a cam ring 4 provided so that the amount of eccentricity is variable with respect to the drive shaft 1. 2, an orifice 8 is interposed in a discharge passage L2 for working fluid (for example, oil), and pressure on the downstream side of the orifice 8 (side away from the discharge port d) is introduced into the control valve 10. The control valve 10 of the variable displacement vane pump in which the discharge amount is variable by controlling the eccentric amount of the cam ring 4 by moving the spool valve body 11 in the control valve 10 (in the longitudinal direction) due to the pressure difference in the longitudinal direction. 2, the outer periphery of the cam ring 4 is contacted with a spring 6 biased in the direction of increasing eccentricity, and the cam ring outer periphery b on the opposite side of the spring 6 The control valve 10 communicates with a working fluid passage (fifth passage) L5, and the spool valve body 11 has two land portions 12A and 12B protruding outward in the radial direction. Thus, the inside of the control valve 10 is divided into three chambers C1, C2, and C3, and the first chamber C1 on one end side of the spool valve body 11 and the discharge port d communicate with each other by a working fluid passage (third passage) L3. A spring 15 for urging the spool valve body 11 toward the first chamber C1 is inserted in the second chamber C2 on the other end side of the spool valve body 11, and the second chamber C2 is an orifice of the discharge passage L2. The third chamber C3 between the land portions 12A and 12B communicates with the suction side passage L1 (the spool valve body 11 is configured to be operable based on the pressure loss at the orifice 8). The first chamber C1 and the third chamber C3 A plurality of openings 13 and 13A are provided symmetrically in the outer peripheral direction (with respect to the central axis in the longitudinal direction of the control valve 10) at the sliding position of the land 12A. Is characterized in that it communicates with the working fluid passage (fifth passage) L5 and communicates with the cam ring outer peripheral portion b on the side facing the spring 6.

The present invention has the following effects by the above configuration.
That is, in the control valve 10, the inserted spool valve body 11 is loaded with the high pressure of the first chamber C1 at one end, and the opening 13 located on the side surface thereof is low pressure. A side force will be generated. However, the openings 13 and 13A are disposed at symmetrical positions in the circumferential direction, and the openings 13 and 13A communicate with the working fluid passage (fifth passage) L5. The pressure at is the same. Therefore, the pressure acting on the spool body 11 at the openings 13 and 13A is also the same, and both cancel each other, so that the spool body 11 is prevented from moving (in the vertical direction in FIG. 1) by the pressure at the openings 13 and 13A. Is done.
Therefore, the spool body 11 is prevented from being worn by interference with other members in the control valve 10, and malfunction does not occur. As a result, the control valve 10 has a long life and reliability is improved.

Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 of the accompanying drawings.
Note that parts similar to those in the related art described with reference to FIGS. 2 and 3 are denoted by the same reference numerals, and redundant description is omitted.
In the embodiment shown in FIG. 1, the pump body portion has the same configuration as that of the prior art described in FIG. The embodiment shown in FIG. 1 is an improvement of the related art with respect to the structure of the control valve. Hereinafter, the improved part will be described with reference to FIG.

In FIG. 1, a spool valve body 11 is slidably inserted in the control valve 10, and the spool valve body 11 has two first and second lands having an annular groove on the outer periphery. The parts 12A and 12B are projected.
The interior of the valve is divided into three chambers, a first chamber C1, a second chamber C2, and a third chamber C3, by the first land portion 12A and the second land portion 12B.

In FIG. 1, the discharge pressure from the pump discharge port d is introduced into the first chamber C1 at the left end via the third passage L3.
A spring 15 is inserted into the second chamber C2 at the right end in FIG. 1, and the spring 15 urges the spool valve body 11 toward the first chamber C1 (left direction in FIG. 1). Further, a pressure downstream of the orifice 8 of the second passage L2 is introduced into the second chamber C2 by the fourth passage L4. Since the second passage L2 communicates with the pump discharge port d, a pressure obtained by subtracting the pressure loss due to the orifice 8 from the pump discharge pressure acts on the second chamber C2.
The third chamber C3 is a region sandwiched between the first land portion 12A and the second land portion 12B. The third chamber C3 communicates with the first passage L1 and has the same pressure as the suction port c.

A first opening 13 and a second opening 13A are formed in the vicinity of the position of the first land portion 12A that separates the first chamber C1 and the third chamber C3.
The two openings 13 and 13A are arranged symmetrically in the circumferential direction. In other words, the two openings 13 and 13A are positioned so that the central angle is 180 °.
The two openings 13 and 13A communicate with each other outside the control valve 10 and communicate with the rear surface b (see FIG. 2) of the cam ring 4 through the fifth passage L5.

With the configuration shown in FIG. 1, the pressure acting on the spool valve body 11 is equal in the vertical direction of FIG. 1. Since the two openings 13 and 13A communicate with the rear surface b (see FIG. 2) of the cam ring 4 via the fifth passage L5, the pressures of the openings 13 and 13A are the same. Then, since there is no pressure difference in the vertical direction of the spool valve body 11 in FIG. 1, the spool body 11 does not move in the vertical direction in FIG.
Therefore, even if the spool body 11 frequently moves in the left-right direction in FIG. 1, the first land portion 12A does not come into contact with other members and wear. Similarly, no stick is generated.

In the illustrated embodiment, the pressure distribution along the outer periphery of the spool valve body 11 is not uniform, thereby preventing the spool valve body 11 from moving in the vertical direction in FIG. It is sufficient if abnormal wear can be prevented. Accordingly, it is not necessary to provide the openings 13 and 13A at exactly symmetrical positions, and they may be arranged at a position of approximately 180 ° (an error of about ± 15 ° is allowed).
Further, the number of openings is not limited to two, and for example, three openings may be arranged 120 degrees apart to make the pressure distribution along the outer periphery of the spool valve body 11 uniform.

  It should be noted that the illustrated embodiment is merely an example, and is not a description to limit the technical scope of the present invention.

Sectional drawing which shows the structure of the control valve which concerns on this invention. Sectional drawing which shows the structure of a variable displacement type vane pump. Sectional drawing which shows the structure of the conventional control valve. The figure which shows the relationship of the flow volume controlled with respect to discharge pressure. The figure which shows the relationship of the flow volume controlled with respect to rotation speed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Drive shaft 2 ... Rotor 3 ... Vane 4 ... Cam ring 6 ... (Cam ring) Spring 10, 10A ... Control valve 11 ... Spool valve body 12A, 12B ... Land portions 13, 13A (opening of spool valve body)... Opening portion 15... (Spool valve) Spring L1 to L6...

Claims (1)

  A rotor (2) is provided inside a cam ring (4) provided so that the amount of eccentricity with respect to the drive shaft (1) is variable, and an orifice (8) is interposed in the discharge passage (L2) for the working fluid. The pressure downstream of the orifice (8) is introduced into the control valve (10), and the spool valve body (11) in the control valve (10) moves due to the pressure difference in the longitudinal direction of the control valve (10). In the control valve (10) of the variable displacement vane pump that controls the eccentric amount of the cam ring (4) to vary the discharge amount, the spring biased in the direction of increasing the eccentric amount on the outer peripheral portion of the cam ring (4) The cam ring outer peripheral portion (b) on the opposite side of the spring (6) and the control valve (10) communicate with each other by a working fluid passage (L5), and the spool valve element (11) ) It has two land portions (12A, 12B) protruding outward in the radial direction, and thus the inside of the control valve (10) is divided into three chambers (C1, C2, C3), and the spool valve body (11 ) And the discharge port (d) communicate with each other through the passage (L3) for the working fluid and communicate with the second chamber (C2) on the other end side of the spool valve body (11). Is inserted with a spring (15) for urging the spool valve body (11) toward the first chamber (C1), and the second chamber (C2) is located downstream of the orifice (8) of the discharge passage (L2). The third chamber (C3) between the land portions (12A, 12B) communicates with the suction side passage (L1), and separates the first chamber (C1) and the third chamber (C3). A plurality of openings (13, 13A) are provided at positions where the land (12A) slides so as to be symmetrical in the outer peripheral direction, and the openings are opened. The variable capacity vane pump is characterized in that the portions (13, 13A) communicate with the working fluid passage (L5) and communicate with the cam ring outer peripheral portion (b) on the side facing the spring (6). Control valve.

Images