JPH0791379A - Variable displacement vane pump - Google Patents

Abstract

PURPOSE:To regulate a discharge flow rate at the specified revolution range as promoting a reduction in required driving torque in a simple structure. CONSTITUTION:A cam ring 26 is rockably installed in a side housing 10, storing a rotor 34 and a vane 40 in the inner part, and a cam ring center 02 is decentered from a rotor turning center 01 by means of resilient force of a spring 32. A first pressure 36 and a second pressure chamber 38 are formed on a circumference of the cam ring 26. An orifice plate 44 is installed in the midway of a fluid discharge path 22 to be situated at the outside of a pump operating chamber 53, interconnecting the second pressure chamber 38 to the upstream side part 22A, thereby forming an interconnecting passage 48 interconnecting a downstream side part 22B and the first pressure chamber 36. With an increment of the discharge flow rate, the cam ring 26 is made so as to be gradually shifted in a direction where an amount of eccentricity is decreased by a pressure differential between both these pressure cars 36 and 38.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement vane pump used as an oil supply pump or the like.

[0002]

2. Description of the Related Art As a variable displacement vane pump as described above, for example, the one disclosed in Japanese Patent Laid-Open No. 3-271579 is known.

As shown in FIG. 5, this pump has a pump housing 8 having a fluid suction passage 81 and a fluid discharge passage 82.
The cam ring 8 in the pump housing 80.
3 is provided, and the rotor 84 is provided inside the cam ring 83.
Is provided. A plurality of vanes 85 are mounted on the outer peripheral portion of the rotor 84 so as to be able to advance and retreat in the radial direction, and the rotor 84 is rotationally driven while the vanes 85 are in sliding contact with the inner peripheral surface 86 of the cam ring 83. ing. The cam ring 83 is swingable around a pivot portion 87, which is an outer peripheral portion of the cam ring 83 and is close to the fluid discharge passage 82, and by this swing, a center O _{2 of the} cam ring 83 and a rotation center O _{1 of the} rotor 84 are formed. The amount of eccentricity is increased or decreased. The space between the outer peripheral surface of the cam ring 83 and the inner peripheral surface of the pump housing 80 includes a primary pressure chamber 91 communicating with the fluid suction passage 81 and a secondary pressure chamber communicating with the fluid discharge passage 82 via a passage 88. And a spring 93 in the pump housing.
Is provided, and the cam ring 83 is urged by the elastic force in a direction in which the eccentric amount increases and the volume of the secondary pressure chamber 92 decreases.

A spool 95 is provided in the fluid discharge passage 82.
And a spring 94 that urges the spring 94 to the upstream side. This flow control valve 96
Is the flow rate in the fluid discharge path 82 (that is, the discharge flow rate)
Is increased, the secondary pressure chamber 9 passes through the passage 88.
2 is configured to feed back a higher control pressure.

According to such a pump, the rotor 8 is
4 can be sucked into the portion between the inner peripheral surface of the cam ring 83 and the outer peripheral surface of the rotor 84 from the fluid suction passage 81 and discharged from the fluid discharge passage 82, and the discharge flow rate can be increased. At a stage where the discharge amount reaches a constant value, the discharge flow rate can be kept constant by swinging the cam ring 83.

More specifically, in a region where the number of revolutions of the rotor 84 per unit time (hereinafter, simply referred to as the number of revolutions) is low, the discharge flow rate increases substantially in proportion to the number of revolutions of the rotor. When the number of revolutions increases to a certain number of revolutions No and the discharge amount reaches a predetermined amount Qo, the flow rate control valve 96 passes through the passage 8
The force for reducing the eccentricity amount of the cam ring 83 due to the control pressure transmitted to the secondary pressure chamber 92 through 8 is the pressure in the primary pressure chamber 91 (that is, the suction pressure) and the spring 93.
And the force that increases the amount of eccentricity is overcome, and the cam ring 83 is swung in the direction in which the amount of eccentricity decreases by the difference between the forces. The pump discharge flow rate is suppressed by this fluctuation amount, and thereafter, the discharge flow rate is prevented from exceeding the predetermined flow rate regardless of the increase in the rotor rotation speed.

[0007]

In the above-mentioned pump, the pressure in the primary pressure chamber 91 is used as the suction pressure, and this pressure and the control pressure in the secondary pressure chamber 92 are balanced, so that the control pressure is obtained. Therefore, the flow control valve 96 including the spool 95 and the spring 94 must be used. Therefore, the number of parts is large, the structure is complicated, and the spool hole needs to be precisely machined, and the assembling work is troublesome. Further, the installation of the flow control valve 96 increases the pressure loss in the fluid discharge passage 82,
This hinders the reduction of drive torque.

In view of such circumstances, it is an object of the present invention to provide a variable displacement vane pump which has a simple structure and is capable of satisfactorily limiting the discharge flow rate while reducing the drive torque.

[0009]

According to the present invention, a pump housing having a fluid intake passage and a fluid discharge passage, a cam ring swingably provided in the pump housing, and a rotary drive provided in the cam ring are provided. The rotor, a plurality of vanes that are provided on the outer peripheral portion of the rotor so as to be able to advance and retreat in the radial direction, and have outer end portions in the radial direction that rotate with the rotor while slidingly contacting the inner peripheral surface of the cam ring, and the center of the cam ring. And a spring means for urging the cam ring in a direction in which the amount of eccentricity between the rotor and the rotation center of the rotor increases, and the rotation of the rotor causes fluid to pass through the fluid suction passage and the inner peripheral surface of the cam ring and the rotor. While being sucked into the space between the outer peripheral surface and discharged from the fluid discharge passage, the center of the cam ring and the rotor are rotating while the cam ring swings. In the variable displacement vane pump configured such that the eccentricity of the fluid changes from the eccentricity, and the discharge flow rate of the fluid from the fluid discharge passage increases or decreases with the change of the eccentricity. A first pressure chamber and a second pressure chamber which are isolated from each other with the swing center of the cam ring as a boundary between them, and the flow of the fluid discharge passage is located in the middle of the fluid discharge passage located outside the pump working chamber. In addition to providing a throttle part that locally narrows the road area,
The second pressure chamber communicates with the upstream side portion of the throttle portion in the fluid discharge passage, and the volume of the second pressure chamber is reduced by the swing of the cam ring in the direction in which the eccentricity increases, so that both pressure chambers are reduced. Is formed, and a communication passage that connects the fluid discharge passage downstream of the throttle portion and the first pressure chamber is formed (Claim 1).

In this pump, it is more preferable that the throttle portion is configured to be attachable to and detachable from the pump housing (Claim 2). On the other hand, while being configured with a cover member that covers from
By forming an orifice plate having a through hole for throttling, the depth dimension thereof is set to be substantially equal to the depth dimension of the side housing, and by forming a mounting groove in the side housing that allows the orifice plate to be inserted and removed in the front-rear direction, A more excellent effect as described below can be obtained (claim 3).

[0011]

In the pump according to the present invention, the rotor is rotationally driven in the cam ring, whereby the fluid is sucked into the cam ring through the fluid suction passage, and the fluid is pressurized and then passed through the fluid discharge passage. It is discharged to the outside.

During such an operation, in a region where the rotor rotational speed is low, that is, in a region where the pump discharge flow rate is small, the pressure reducing action in the throttle portion is small, and therefore the pressure in the secondary pressure chamber (that is, the discharge pressure) and the primary pressure. Since the pressure difference with the pressure in the chamber (that is, the pressure on the downstream side of the throttle portion) is low, the cam ring is held in a state where the eccentric amount between the center of the cam ring and the rotor rotation center is large due to the urging force of the spring means. Therefore, in this state, the discharge flow rate increases as the rotor rotation speed increases.

However, as the rotor speed and the discharge flow rate increase, the pressure reducing action in the throttle portion increases, and the pressure in the fluid discharge passage upstream of the throttle portion, that is, the pressure in the secondary pressure chamber and the throttle portion. Since the pressure in the fluid discharge passage on the downstream side, that is, the pressure difference with the pressure in the primary pressure chamber gradually increases, when the rotor speed reaches a certain speed,
The force acting on the cam ring due to the differential pressure overcomes the biasing force of the spring means, and the cam ring is gradually rotated in the direction in which the amount of eccentricity decreases. As a result, the volume of the pump displacement chamber (effective volume) gradually decreases, and the increase in the discharge flow rate due to the increase in the rotor speed is regulated.

Since the relationship between the pump discharge flow rate and the differential pressure generated in the throttle portion varies depending on the inner diameter and shape of the throttle portion, the vane pump according to the second aspect of the invention has throttle portions having different inner diameters and shapes. The converging discharge flow rate can be changed by appropriately replacing and mounting. More specifically, in the vane pump according to the third aspect, the orifice plate that is the throttle portion is inserted into the mounting groove provided in the side housing, and then the cover member is attached to the front and rear of the side housing to attach the orifice plate. It can be performed.

[0015]

An embodiment of the present invention will be described with reference to FIGS.

The illustrated variable displacement vane pump includes a side housing 10, and a front plate 12 and a rear plate 14 (both of which constitute a cover member) as shown in FIG. Is configured. A pump shaft 16 faces the inside of the pump housing so as to pass through the central portion of the rear plate 14. The pump shaft 16 is connected to a drive source (not shown) and a bearing (not shown). It is rotatably supported on the rear plate 14 side. The pump housing includes a fluid suction passage 20.
And a fluid discharge passage 22 are formed, and both passages 20, 22 are formed.
Open into the pump housing.

In this pump housing, both paths 2
Cam ring (swing ring) 26 at a position facing 0, 22
The front plate 1 is provided on both front and rear sides thereof.
2 and the inner surface of the rear plate 14, respectively. On the outer peripheral portion of the cam ring 26, in the vicinity of the fluid discharge passage 22, there is formed a substantially circular pivot portion 28 protruding radially outward. This pivot part 28
Is fitted in a recess of substantially the same shape formed at the lower end of the side housing 10, whereby the cam ring 2
6 is swingable around the center point of the pivot portion 28, and this swing increases or decreases the eccentric amount of the center O ₂ of the cam ring 26 with respect to the rotation center O ₁ of the pump shaft 16. Has become.

Similarly, on the outer peripheral portion of the cam ring 26,
A protruding portion 30 is formed at a position separated from the pivot portion 28 by approximately 180 °. A recess 31 is formed at an appropriate position in the pump housing, and a spring (spring means) 32 that comes into contact with the protrusion 30 is press-fitted into the recess 31. Due to the elastic force of the spring 32, the eccentric amount is reduced. The cam ring 26 is biased in the increasing direction (upward in the figure).

Inside the cam ring 26, the rotor 3
4 are provided. The rotor 34 has an inner ring-shaped portion 34A having a smaller depth dimension (depth dimension in FIG. 1) than the side housing 10 and an outer ring-shaped portion 34B having a depth dimension substantially equal to that of the side housing 10. Are connected via a connecting portion 34C having a depth dimension smaller than that of the inner ring-shaped portion 34A. The inner ring-shaped portion 34A is connected to the pump shaft 16 so as to rotate integrally therewith.

A plurality of vanes 40 are arranged at equal intervals in the outer ring-shaped portion 34B so as to penetrate the outer ring-shaped portion 34B in the radial direction, and each vane 40 can be individually advanced and retracted in the radial direction. There is. Inside the vanes 40, vane projecting rings 42 are provided at positions on both the left and right sides of the connecting portion 34C, and as the rotor 34 rotates, each vane 40 causes centrifugal force of the vanes 40 themselves and The vane projecting ring 42 projects radially outward, and the outer end surface of the vane projecting ring 42 has an inner peripheral surface 27 of the cam ring 26.
It is designed to slide on.

A recess 33 is formed in the side housing 10 at a position corresponding to the protrusion 30, and an inner peripheral surface of the recess 33 and an outer peripheral surface of the protrusion 30 are in contact with each other.
A space between the outer peripheral surface of the cam ring 26 and the inner peripheral surface of the side housing 10 is divided into a first pressure chamber 36 and a second pressure chamber 38 with the contact portion and the pivot portion 28 as a boundary. Here, the spring 32 is provided on the side of the first pressure chamber 36, and the swing of the cam ring in the direction of its elastic force increases the volume of the first pressure chamber 36, and conversely, the second pressure chamber 36. The volume of 38 is designed to decrease.
The positions of both pressure chambers 36 and 38 are the same as those of the second pressure chamber 3 described above.
Only 8 is set to face the inlet portion of the fluid discharge passage 22.

Further, as a feature of this pump, an orifice plate 44 as a throttle portion is attached in the middle of the fluid discharge passage 22 located outside the pump working chamber 53 accommodating the rotor 34, the vanes 40, the cam ring 26 and the like. ing. In this embodiment, the orifice plate 44 is made of a rectangular thin plate as shown in FIGS. 3A and 3B, and the dimension (width dimension) of its long side is the width dimension of the fluid discharge passage as viewed from the front (in FIG. 1). It is set larger than the width dimension, and the dimension of the short side (depth dimension) is set to be substantially equal to the depth dimension of the side housing 10 (left and right dimension in FIG. 2).
A through hole 46 for throttling is provided in the center of the orifice plate 44, and the diameter of the through hole 46 is set so that the through hole 46 is one size smaller than the flow passage cross section of the fluid discharge passage 22.

As a mounting structure of the orifice plate 44, mounting grooves 42 having a U-shape in a front view are formed at both sides of the fluid discharge passage 22 in the side housing 10. Then, both ends of the orifice plate 44 are inserted into the mounting groove 42, and thereafter, the front plate 12 and the rear plate 14 are mounted on both sides of the side housing 10, so that the orifice plate 44 is closed. Has become.

That is, the orifice plate 44 is constructed so as to be attachable to and detachable from the pump housing, and the portion 22A on the upstream side of the orifice plate 44 in the fluid discharge passage 22 is communicated with the second pressure chamber 38. In addition, the side housing 10 has a fluid discharge passage 22.
In the communication passage 48 for communicating the portion 22B on the downstream side of the orifice plate 44 with the first pressure chamber 36
Are formed.

Next, the operation of this variable displacement vane pump will be described.

When the rotor 34 is driven to rotate integrally with the pump shaft 16 in the cam ring 26 from the initial state as shown in FIG. 1, the fluid suction passage 20 is introduced into the cam ring 26.
A fluid is sucked in through the fluid, and the fluid is pressurized and then discharged to the outside of the pump housing through the fluid discharge passage 22.

During such an operation, the orifice plate 44 has its upstream side pressure P1 due to its throttling action.
Pressure difference ΔP (= P1-P2>
0) occurs. The relationship between the differential pressure ΔP and the pump discharge flow rate Q is generally given by the following equation.

[0028]

## EQU1 ## ΔP = CQ ² where C is the through hole 46 in the orifice plate 44.
Is a constant determined by the hole diameter and shape, the fluid viscosity characteristics, and so on.

Therefore, the region where the rotation speed of the rotor 34 is low,
That is, in a region where the pump discharge flow rate Q is small, the pressure reducing action in the orifice plate 44 is small, and the differential pressure between the pressure in the secondary pressure chamber (that is, the upstream pressure P1) and the pressure in the primary pressure chamber (that is, the downstream pressure P2). ΔP
Therefore, the cam ring 26 is held in a state in which the eccentric amount between the center O _{2 of the} cam ring 26 and the rotor rotation center O ₁ is large due to the urging force of the spring 32. Therefore,
In this state, the discharge flow rate also increases as the rotor rotation speed increases.

However, this rotor speed and discharge flow rate Q
As the pressure increases, the pressure reducing action of the orifice plate 44 increases, and the pressure P1 in the fluid discharge passage upstream of the orifice plate 44, that is, the pressure in the secondary pressure chamber 38 and the fluid discharge downstream of the orifice plate 44. Since the pressure P2 in the passage, that is, the pressure difference ΔP from the pressure in the primary pressure chamber 36 gradually increases (refer to the above-mentioned formula 1), when the rotor speed reaches a certain speed, the pressure difference ΔP causes The force acting on the cam ring 26 is the spring 32.
The cam ring 26 is gradually rotated in the direction in which the amount of eccentricity decreases (downward in FIG. 1) by overcoming the urging force of the cam ring 26. As a result, the volume of the pump displacement chamber (effective volume) can be gradually reduced, and an increase in the discharge flow rate due to an increase in the rotor rotation speed can be effectively suppressed.

FIG. 4 shows the results of simulations executed for the pump of this embodiment and the pump for which the flow rate is not controlled, as a solid line 51 and a chain line 52, respectively. As shown by the alternate long and short dash line 52, if no flow rate control is performed, the discharge flow rate will increase without limitation substantially in proportion to the rotor rotation speed, but as shown by the solid line 51,
According to the pump of the present embodiment, by appropriately setting the shape of the orifice plate 44, the pump discharge flow rate can be converged to a desired flow rate in a region where the pump rotation speed is high.

Moreover, in the conventional vane pump as shown in FIG. 5, a large number of parts such as the spool 95 and the spring 94 are required for controlling the flow rate, and the assembling work and the machining of the spool hole are troublesome. On the other hand, according to the vane pump of the present embodiment, the orifice plate 44 is provided in the middle of the fluid discharge passage 22, and the discharge passage 22B and the first discharge passage 22B on the downstream side are provided.
The discharge flow rate can be reliably controlled with a simple structure in which the pressure chamber 36 and the pressure chamber 36 are communicated with each other through the passage 48. Further, compared with the case where the flow rate control valve is provided in the fluid discharge passage, the pressure loss in the orifice plate 44 is small, and the required drive torque can be reduced accordingly.

The shape of the throttle portion may be set as appropriate, and in the pump according to claim 1 of the present application, the throttle portion may be formed integrally with the pump housing. However, if the throttle portion such as the orifice plate 44 is configured to be attachable / detachable to / from the pump housing as in the above embodiment, by appropriately exchanging a plurality of types of throttle portions having different shapes and throttle inner diameters, There is an advantage that the convergent discharge flow rate can be easily changed according to the application of the pump. Particularly, in the pump of this embodiment, the pump housing is composed of the side housing 10 and the front plate 12 and the rear plate 14 that cover the side housing 10 from the front and rear, and the depth dimension of the orifice plate 44 is set to be substantially equal to the depth dimension of the side housing 10. Since the mounting groove 42 is formed in the side housing 10, the mounting groove 42
The orifice plate 44 can be attached by a simple operation in which the orifice plate 44 is inserted into and the both plates 12 and 14 are attached to the front and rear of the side housing 10.

[0034]

As described above, according to the present invention, the first pressure chamber and the second pressure chamber, which are isolated from each other, are formed around the cam ring, and at the middle of the fluid discharge path located outside the pump working chamber. A throttle portion is provided, and the second pressure chamber is communicated with a fluid discharge passage upstream of the throttle portion, and a communication passage communicating the fluid discharge passage downstream of the throttle portion with the first pressure chamber is formed. Since the discharge flow rate is reduced with the swing of the cam ring in the direction in which the volume of the second pressure chamber increases, a simple structure is simply provided with the throttle portion and the communication passage. It is possible to easily and reliably regulate the discharge flow rate in a predetermined rotation speed range, reduce the pressure loss in the fluid discharge path, and reduce the required drive torque compared to the structure in which a flow rate control valve or the like is provided in the middle of the fluid discharge path. Effects that can be reduced There is.

Further, in the pump according to the second aspect of the invention, since the throttle portion is configured to be attachable to and detachable from the pump housing, the throttle portions having different throttle diameters and shapes are appropriately replaced and mounted on the pump housing. As a result, the limited discharge flow rate can be easily changed according to the application of the pump and the like.

Particularly, in the pump according to the third aspect, the orifice plate is mounted by a simple operation of inserting the orifice plate into the mounting groove formed in the side housing and then mounting the cover members at the front and rear of the side housing. There is an effect that can be done.

[Brief description of drawings]

FIG. 1 is a front view showing a state in which a front plate is removed in a variable displacement vane pump according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3A is a plan view of an orifice plate provided in the variable displacement vane pump, and FIG. 3B is B of FIG.
It is a -B line sectional view.

FIG. 4 is a graph showing the relationship between the pump rotational speed and the discharge flow rate in the vane pump and the vane pump in which the flow rate control is not performed.

FIG. 5 is a front view showing an example of a conventional vane pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Side housing 12 Front plate (constituting cover member) 14 Rear plate (constituting cover member) 20 Fluid suction passage 22 Fluid discharge passage 26 Cam ring 27 Cam ring inner peripheral surface 28 Pipott portion 32 Spring (spring means) 34 Rotor 40 vane 42 Vane protruding ring 44 Orifice plate (throttle portion) 46 Through hole for throttle 48 Communication passage

Claims (3)

[Claims] 1. A pump housing having a fluid suction passage and a fluid discharge passage, a cam ring swingably provided in the pump housing, and a cam ring provided in the cam ring.
A rotor that is driven to rotate, a plurality of vanes that are provided on the outer peripheral portion of the rotor so as to be able to advance and retreat in the radial direction, and that have outer end portions in the radial direction that are in sliding contact with the inner peripheral surface of the cam ring and that rotate with the rotor; And a spring means for urging the cam ring in a direction in which the amount of eccentricity between the center of the rotor and the center of rotation of the rotor increases, and by the rotation of the rotor,
Fluid is sucked into the space between the inner peripheral surface of the cam ring and the outer peripheral surface of the rotor through the fluid suction passage, is discharged from the fluid discharge passage, and the center of the cam ring is accompanied by the swing of the cam ring. And a center of rotation of the rotor, the amount of eccentricity changes, and the discharge flow rate of the fluid from the fluid discharge passage increases or decreases in accordance with the change in the amount of eccentricity. A first pressure chamber and a second pressure chamber are formed between the peripheral surface and the outer peripheral surface of the cam ring, the first pressure chamber and the second pressure chamber being separated from each other with the swing center of the cam ring as a boundary, and in the middle of the fluid discharge passage located outside the pump working chamber. A throttle portion for locally narrowing the flow passage area of the fluid discharge passage is provided, and the second pressure chamber communicates with the upstream side portion of the throttle portion in the fluid discharge passage and the volume of the second pressure chamber is The formation positions of both pressure chambers are set so that the eccentricity decreases due to the swinging of the cam ring in the direction of increasing the eccentricity, and the fluid discharge passage downstream of the throttle portion communicates with the first pressure chamber. A variable displacement vane pump having a communication passage. 2. The variable displacement vane pump according to claim 1, wherein the throttle portion is configured to be attachable to and detachable from the pump housing. 3. The variable displacement vane pump according to claim 2, wherein the pump housing includes a side housing and a cover member that covers the side housing from the front and the back, and the throttle portion includes a through hole for throttle. A variable capacity type characterized in that the orifice plate has a depth dimension substantially equal to the depth dimension of the side housing, and a mounting groove for forming the orifice plate in the front-rear direction is formed in the side housing. Vane pump.