JPH03271580A - Variable displacement type vane pump - Google Patents

Abstract

PURPOSE:To control the eccentricity of a cam ring in response to a discharge quantity by engaging a pivot part with a recessed part for pivot turnably, and supporting the cam ring with a pump housing freely to oscillate, and while leading the fluid pressure in both upstream and downstream sides of a throttle part into multiple control pressure chambers. CONSTITUTION:When a rotor 3 is rotated, each pump chamber 6 is rotated for movement, repeating increase and decrease of capacity. Most of the fluid discharged to a discharge port 95a is led to a fluid discharge passage 12 through a communicating passage 7. A throttle part 73 is provided in the communicating passage 7 between the discharge port 95a and a fluid discharge passage 12. The fluid pressure P1 of the upstream side of the throttle part 73 is led into a first control pressure chamber 91, and the fluid pressure P2 of the downstream side of the throttle part 73 is led into a second control pressure chamber 92. The fluid pressure P1 works on a cam ring 2 in the direction for reducing the eccentricity, and the fluid pressure P2 works on the cam ring 2 in the direction for increasing the eccentricity beside the spring force F of a cam spring 25 working on the cam ring 2 in the direction for increasing the eccentricity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable displacement vane pump used, for example, as an oil supply pump for automatic transmissions of automobiles.

[Conventional technology]

Conventionally, this type of variable displacement vane pump is known, for example, as shown in Japanese Utility Model Publication No. 19597/1983.

This conventional pump includes a pump housing having a fluid suction passage and a fluid discharge passage, a cam ring (oscillating ring) provided within the pump housing, a rotor provided within the cam ring and driven to rotate, and a rotor provided within the cam ring that is rotatably driven. A plurality of vanes are provided on the outer circumferential portion of the rotor so as to be movable in the radial direction and whose outer ends in the radial direction are in sliding contact with the inner circumferential surface of the cam ring. Approximately semicircular recesses facing each other are formed in the inner circumferential surface of the pump housing and the outer circumferential surface of the cam ring, and these recesses are fitted into support pins having a circular cross section disposed between the two recesses. As a result, the cam ring is swingably supported by the pump housing via the support pin so that the center of the cam ring can be eccentric with respect to the rotational axis of the rotor. Further, this cam ring is biased in the direction of increasing eccentricity by a spring force of a cam spring.

With the above configuration, this conventional pump sucks fluid into the space between the inner circumferential surface of the cam ring and the outer circumferential surface of the rotor through the fluid suction path by rotating the rotor, and draws the fluid into the space between the inner circumferential surface of the cam ring and the outer circumferential surface of the rotor. The fluid can be discharged from the cam ring, and the amount of fluid discharged from the fluid discharge passage can be changed in accordance with the amount of eccentricity of the cam ring. Further, this conventional pump is configured to control the amount of eccentricity of the cam ring according to the discharge amount, and as a result, the discharge amount characteristics as shown in FIG. 5, for example, can be obtained. There is.

[Problem to be solved by the invention]

As described above, in the conventional pump configuration, a support pin is separately provided to swingably support the cam ring. This resulted in an increase in the number of parts.

Further, in the conventional pump described above, in order to control the amount of eccentricity of the cam ring according to the discharge amount, the pump was configured as follows.

That is, a control pressure chamber is formed in which control fluid pressure is introduced into the space between the inner peripheral surface of the pump housing and the outer peripheral surface of the cam ring, and the control fluid pressure urges the cam ring in the direction of decreasing eccentricity. A flow control valve consisting of a spool and a spool spring is disposed in the fluid discharge path, and the flow control valve generates a control fluid pressure according to the flow rate (discharge amount) passing through the fluid discharge path. guiding control fluid pressure to the control pressure chamber through a control fluid pressure introduction path formed in the pump housing;
The amount of eccentricity of the cam ring was controlled according to the control fluid pressure.

In this way, conventional pump configurations use a flow control valve with a spool that requires highly precise machining in order to control the amount of eccentricity of the cam ring according to the discharge amount, which increases costs. Ta.

In view of the above circumstances, it is an object of the present invention to provide a variable displacement vane pump that can be constructed at low cost with a small number of parts.

[Means to solve the problem]

A variable displacement vane pump according to the present invention includes a pump housing having a fluid suction path and a fluid discharge path, a cam ring provided in the pump housing, a rotor provided in the cam ring and driven to rotate, and a rotor provided in the cam ring to be rotated. a plurality of vanes provided on the outer periphery of the cam ring so as to be movable in the radial direction and whose radially outer ends slide against the inner periphery of the cam ring, the cam ring having its center relative to the rotational axis of the rotor. is swingably supported by the pump housing so as to be eccentric, and is urged in a direction to increase the amount of eccentricity by a spring force of a cam spring;
By rotating the rotor, fluid is drawn into the space between the inner circumferential surface of the cam ring and the outer circumferential surface of the rotor through the fluid suction passage, and is discharged from the space through the fluid discharge passage. In the variable displacement vane pump, the eccentricity of the cam ring is controlled according to the amount of fluid discharged from the fluid discharge passage, and the discharge amount is changed according to the eccentricity of the cam ring. A pivot portion is integrally formed on a portion of the outer peripheral surface of the cam ring, and a pivot recess is formed on a portion of the inner peripheral surface of the pump housing, and the pivot portion is rotatable in the pivot recess. By being fitted, the cam ring is swingably supported, and fluid pressure is introduced into the space between the inner circumferential surface of the pump housing and the outer circumferential surface of the cam ring, and the cam ring is moved by the fluid pressure. A first control pressure chamber biasing the cam ring in the direction of decreasing the amount of eccentricity and a second control pressure chamber into which fluid pressure is introduced and biasing the cam ring in the direction of increasing the amount of eccentricity are formed; A communication passage is provided in which the space between the inner circumferential surface of the cam ring and the outer circumference of the rotor communicates with the fluid discharge passage, and a constriction part is provided in the middle of this communication passage, and a constriction part is provided in the middle of the constriction part. is introduced into the first control pressure chamber, and
The fluid pressure on the downstream side of the throttle section is configured to be introduced into the second control pressure chamber.

[Effect]

According to the above configuration, the fluid pressure on the downstream side of the throttle part is lower than the fluid pressure on the upstream side of the throttle part. The high fluid pressure upstream of the throttle part is introduced into the first control pressure chamber that biases the cam ring in the direction of decreasing eccentricity, and the low fluid pressure downstream of the throttle part biases the cam ring in the direction of increasing eccentricity. is introduced into the second control pressure chamber. Therefore, the pressure difference between the high and low fluid pressures acts on the cam ring against the spring force of the cam spring, and the eccentricity of the cam ring is controlled by the force relationship between the pressure difference and the spring force. . In other words, the amount of eccentricity of the cam ring is controlled according to the differential pressure.

Moreover, since the differential pressure changes depending on the flow rate (discharge amount) passing through the constriction portion, the force and the eccentricity of the mulling are controlled according to the discharge amount.

〔Example〕

1 and 2 show an embodiment of a variable displacement vane pump according to the present invention.

This variable displacement vane pump includes a pump housing 1, an annular cam ring 2, and a rotor 3.

The pump housing 1 consists of a housing body 1a and a cover-side housing 1b, and a cylindrical recess with one end opened is formed in the center of the housing body 1a. It is closed and forms a housing inner cavity 1C. Also,
No. 1 A fluid suction passage 11 and a fluid discharge passage 12 are formed to penetrate through the housing body 1a, and one end of each of the fluid suction passage 11 and fluid discharge passage 12 is connected to the housing body 1a.
An inlet port 11a and a discharge port 12a are formed by opening at the outer peripheral flange portion. Note that a part of the fluid suction path 11 is also formed in the cover-side housing 1b. Surface of the housing inner cavity 1c (pump housing inner peripheral surface) 1
A substantially C-shaped pivot recess 18 is formed in a part of the pivot recess 18 , and the other end of the fluid discharge passage 12 opens into the pivot recess 18 .

The cam ring 2 has a circular inner circumferential surface 21, and both sides thereof are inserted into the housing inner cavity IC.
The pump housing is provided in close contact with the inner surface 13.14 of the pump housing facing the.

The rotor 3 is formed to have a smaller diameter than the circular inner circumferential surface 21 of the cam ring 2, and is provided within the circular inner circumferential surface 21 of the cam ring 2 with both side surfaces in close contact with the pump housing inner surfaces 13 and 14, respectively. .

Further, in this rotor 3, a rotor drive shaft (not shown) inserted through the cover-side housing 1b is connected via a drive flange 3a, and the axis α of the rotor drive shaft passes through the center O0 of the pump housing inner peripheral surface 15. It is designed to rotate in the direction of arrow C in FIG. 1 about .

A plurality of vane grooves 31 are formed radially on the outer circumference of the rotor 3. Each vane groove 31 is connected to the rotor outer peripheral surface 32.
A vane 4 is fitted into each vane groove 31 so as to be movable in the radial direction of the rotor.

Annular grooves 33 and 34 are formed on both side surfaces of the rotor 3, respectively, and a guide ring 35 is disposed in the groove 34 formed on the inner side surface 14 of the pump housing.

The vane 4 is urged outward in the rotor radial direction by the guide ring 35 and the centrifugal force accompanying the rotation of the rotor 3,
The outer end in the radial direction is always pressed against the circular inner circumferential surface 21 of the cam ring 2 and is configured to come into sliding contact with the circular inner circumferential surface 21.

A pivot portion 23 is provided on a part of the outer peripheral surface 22 of the cam ring 2.
are integrally formed to protrude. This pivot portion 23 includes a cylindrical head 23a, and an outer peripheral surface 22 between the head 23a and the cylindrical head 23a.
and a neck portion 23b connecting the two. Then, the head 23a of the pivot portion 23 is rotatably fitted into the pivot recess 18, and the cam ring 2 is attached to the pump The cam ring 2 is supported so as to be able to swing in the directions of arrows A and B in FIG. The center (center of the circular inner circumferential surface 21) 03 can be eccentric with respect to the rotation axis α of the rotor 3.The distance from the pivot point 02 to the rotation axis α of the rotor 3 and the distance from the pivot point 02 The distance is set to be equal to the distance to the center 03 of the cam ring 2.

A spring seat 24 is formed protrudingly on one side of the outer circumferential surface 22 of the cam ring 2, bordering on the center line β passing through the pivot point 02 and the center 03 of the cam ring 2. This spring seat 24 has a cam spring 2 that urges the cam ring 2 in the direction of increasing eccentricity (in the direction of arrow B in FIG. 1).
A spring force of 5 is applied, thereby pressing the cam ring 2 to the maximum eccentric position.

Further, a stopper surface 26 is formed on the other side of the outer circumferential surface 22 of the cam ring 2 bordering on the center line β, which abuts against the pump housing inner circumferential surface 15 at the maximum eccentric position of the cam ring 2 to stop the movement of the cam ring 2. has been done.

On the outer periphery of the cam ring 2, there are first and second seal grooves 27, 28 extending in the radial direction of the cam ring 2 at equal intervals from the pivot portion 23 on one side and the other side of the center line β. It is formed. The first and second seal grooves 27.28 each open to the cam ring outer circumferential surface 22, and the first and second plate-shaped seal members 51.52 are respectively installed in the first and second seal grooves 27.28 of the cam ring. It is fitted so that it can move forward and backward in the radial direction.

The space between the pump housing inner circumferential surface 15 and the cam ring outer circumferential surface 22 is formed by the first and second seal members 51.
．． 52 and the pivot part 23, the first control pressure chamber 91 is between the pivot part 23 and the first seal member 51, the pivot roll pressure chamber 92 is between the first seal member 51 and the second seal member. A drain chamber 93 is formed between each of the drain chambers 52 and 52 .

Fluid pressure is introduced into the first and second control pressure chambers 91 and 92, respectively, as will be described later, and the first control pressure chamber 91 uses the introduced fluid pressure to bias the cam ring 2 in the direction of decreasing the amount of eccentricity. The second control pressure chamber 92 is configured to bias the cam ring 2 in the direction of increasing the amount of eccentricity by the introduced fluid pressure. Further, the other end of the fluid suction path 11 is open to the drain chamber 93 .

The pivot part 23 is provided with both sides in close contact with the inner side surfaces 13, 14 of the pump housing, respectively. Therefore, the pivot portion 23 is given a sealing action, and the space between the first control pressure chamber 91 and the second control pressure chamber 92 is sealed by the pivot portion 23 . Further, the pivot portion 23 connects the fluid discharge passage 12 which opens into the pivot recess 18 with the fluid discharge passage 12 .

At the radially inner end of each of the seal grooves 27, 28, there is a fourth groove.
As shown in the figure, back pressure chambers 27a and 28a are provided, and each back pressure chamber 27a and 28a has back pressure introduction paths 27b and 2, respectively.
8b via each corresponding control pressure chamber 91.92
The internal fluid pressure is introduced. Each sealing member 51, 52 receives the fluid pressure introduced into each back pressure chamber 27a, 28a at its radially inner end, and its radially outer end is constantly pressed against the pump housing inner circumferential surface 15 by the fluid pressure. It is being For this reason, each seal member 51
．． 52 reliably seal between the first control pressure chamber 91 and the drain chamber 93 and between the second control pressure chamber 92 and the drain chamber 93.

The inner peripheral surface 21 of the cam ring 2 and the outer peripheral surface 32 of the rotor 3
A space surrounded by the inner surface 13, 14 of the pump housing is divided into a plurality of parts by the vane 4, and a plurality of pump chambers 6 are formed in the space. The center 03 of the cam ring 2 is eccentric with respect to the rotational axis α of the rotor 3, so that the volume of each pump chamber 6 increases or decreases as the rotor 3 rotates.

A suction groove 94 and a discharge groove 95 are formed in the inner surface 13 of the pump housing l. The suction groove 94 communicates with the fluid suction path 11, opens into the pump chamber 6a in the process of increasing its volume, and the opening constitutes a suction port 94a.

On the other hand, the discharge groove 95 extends from the central position of the head of the pivot portion 23 to the position of the pump chamber 6b in the process of volume reduction, opens into the pump chamber 6b, and constitutes a discharge port 95a at the opening. Further, this discharge groove 95 also extends to the first control pressure chamber 91 position and opens into the pressure chamber 91,
Thereby, the discharge port 95a and the first control pressure chamber 91 are communicated via the discharge groove 95. In addition,
The discharge groove 95 has a width that allows sufficient sealing between the discharge groove 95 and the second control pressure chamber 92 even when the cam ring 2 swings, and the side surface of the pivot portion 23 and the pump housing. It is formed so that a contact portion with the inner surface 13 is secured.

As shown in FIG. 3, the head 23a of the pivot portion 23 has a cylindrical recess 71 that opens toward the discharge groove 95;
A communication path 7 is formed by the recess 71 and a through hole 72 that opens toward the other end of the fluid discharge path 12.
a) and the fluid discharge path 12 are in communication with each other. In the middle of the communication path 7 (the end of the through hole 72 on the recess 71 side), there is a constriction part (
An orifice 73 is provided. Further, in the housing body 1a, a fluid pressure introduction path 8 on the downstream side of the constriction portion that communicates the middle of the fluid discharge path 12 with the second control pressure chamber 92 is provided.
3 is formed.

In the above configuration, when the rotor 3 is rotated in the direction of arrow C from the state shown in the first engineering drawing (the state in which the cam ring 2 is maximally eccentric), each pump chamber 6 also rotates in the direction of arrow C while repeating increase and decrease in volume. .

Each pump chamber 6 communicates with the suction port h94a during the volume increase process, and connects the suction port 11a to the fluid suction path 1.
1 to the suction port 94a, and during the volume reduction process communicates with the discharge port 95a to discharge the sucked fluid toward the discharge port 95a. A part of the fluid discharged into the discharge port (discharge port) 95a is introduced into the first control pressure chamber 91 through the discharge groove 95, and most of the remaining fluid is guided into the fluid discharge passage 12 through the communication passage 7. . Thereafter, part of the fluid guided to the fluid discharge path 12 is introduced into the second control pressure chamber 92 through the fluid pressure introduction path 83 on the downstream side of the constriction part, and most of the remaining fluid is discharged from the discharge port 12a. .

Incidentally, in this pump, a constriction portion 73 is provided in the communication path 7 between the discharge port 95a and the fluid discharge path 12. Therefore, a pressure difference is generated before and after the constriction portion 73. That is, the fluid pressure P2 in the fluid discharge passage 12 portion on the downstream side of the throttle portion 73 is lower than the fluid pressure P1 in the discharge port 95a portion on the upstream side of the throttle portion 73.

The fluid pressure P□ at the discharge port 95a portion on the upstream side of the throttle portion 73 is introduced into the first control pressure chamber 91, and the fluid pressure P2 at the fluid discharge passage 12 portion on the downstream side of the throttle portion 73 is introduced into the second control pressure chamber 91. It is introduced into the pressure chamber 92. As a result, in addition to the spring force F of the cam spring 25 that acts on the cam ring 2 in the direction of increasing the amount of eccentricity, the fluid pressure P acts on the cam ring 2 in the direction of decreasing the amount of eccentricity, and the fluid pressure P2 acts in the direction of increasing the amount of eccentricity. It becomes effective. In other words, the cam ring 2 has a differential pressure ΔP (=
P knee P2) comes to act against the spring force F of the cam spring 25.

The above differential pressure ΔP is the flow rate (discharge amount) passing through the throttle part 73
It increases in proportion to the square of Q. Further, the discharge amount Q increases in proportion to the rotation speed N of the rotor 3. Therefore, when the rotational speed N of the rotor 3 is low, the discharge amount Q is small and the differential pressure Δ
P also becomes smaller.

Therefore, in this case, the spring force F of the cam spring 25 is greater than the force exerted on the cam ring 2 due to the differential pressure ΔP.
The cam ring 2 is held at the maximum eccentric position. As a result,
When the rotation speed N of the rotor 3 is low, the discharge amount Q increases in proportion to the rotation speed N.

On the other hand, as the rotation speed N of the rotor 3 increases, the discharge amount Q increases and the differential pressure ΔP also increases. Here, for example, if the spring force F of the cam spring 25 is set to balance with the force due to the differential pressure ΔP when the discharge amount Q reaches a predetermined amount Qo, the rotation speed N of the rotor 3 will increase. When the discharge amount Q reaches a predetermined amount Qo, the force due to the differential pressure ΔP overcomes the spring force F of the cam spring 25, and the cam ring 2 begins to swing in the direction of decreasing the amount of eccentricity. As a result, the amount of eccentricity of the cam ring 2 is reduced, the displacement volume is reduced, and the discharge amount Q is maintained not to exceed the predetermined amount Qo.

That is, according to the configuration of this pump, as shown in FIG. 5, when the rotation speed N of the rotor 3 is low, the discharge amount Q increases in proportion to the rotation speed N, and when the rotation speed N of the rotor 3 is high, the discharge amount Q increases. Even if the rotational speed N increases, the discharge amount Q can be controlled so that the discharge amount Q does not exceed a certain amount Qo. Moreover, the discharge rate characteristics shown in FIG. 5 can be obtained without using a flow rate control valve having a spool or the like, and the structure can be constructed at low cost.

6 and 7 show another embodiment.

This pump connects the fluid suction path 11 directly to the suction port 94a by bypassing the space between the pump housing inner circumferential surface 15 and the cam ring outer circumferential surface 22, and A cylindrical seal member 54 is held and interposed in the housing body 1a at a position substantially opposite to the pivot portion 23 between the housing body 22 and the pivot portion 23.

Then, the space between the pump housing inner circumferential surface 15 and the cam ring outer circumferential surface 22 is divided into two by the seal member 54 and the pivot portion 23.
A first control pressure chamber 91 is provided on one side, and a second control pressure chamber 92 is provided on the other side.

With this configuration, the drain chamber 93 becomes unnecessary and the number of seal members can be reduced.

〔Effect of the invention〕

In the variable displacement vane pump according to the present invention, a pivot portion is integrally formed on a part of the outer peripheral surface of the cam ring, and a recess for the pivot is formed in a part of the inner peripheral surface of the pump housing. By rotatably fitting the parts, the cam ring is swingably supported on the pump housing. Therefore, the cam ring can be swingably supported without providing a separate support pin, and the support pin becomes unnecessary.

Moreover, in the configuration of this pump, in the space between the inner peripheral surface of the pump housing and the outer peripheral surface of the cam ring,
A first control pressure chamber into which fluid pressure is introduced and which urges the cam ring in a direction to decrease the amount of eccentricity; and a second control chamber into which fluid pressure is introduced and which urges the cam ring in a direction to increase the amount of eccentricity. A pressure chamber is formed, a communication path is provided in the pivot portion to communicate the fluid discharge path with a space between the inner peripheral surface of the cam ring and the outer peripheral surface of the rotor, and a throttle portion is provided in the middle of this communication path. The fluid pressure on the upstream side of the throttle part is introduced into the first control pressure blade chamber, and the fluid pressure on the downstream side of the throttle part is introduced into the second control pressure chamber. Therefore, the amount of eccentricity of the cam ring can be controlled according to the discharge amount without using a flow control valve having a spool or the like.

Therefore, it is possible to construct an inexpensive variable displacement vane pump that does not require a support bottle or a flow rate control valve.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of the variable displacement vane pump according to the present invention, excluding the cover side housing, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 1, and FIG. 4 is a sectional view taken along the line IV-IV of FIG. 1, FIG. 5 is a graph showing the relationship between rotor rotational speed and discharge amount,
The figure is a front view showing another embodiment with the cover side housing removed, and FIG. 7 is a sectional view taken along the line ■--■ in FIG. 6. 1... Pump housing, 2... Cam ring, 3...
... Rotor, 4... Vane, 7... Communication path, 11.
...Fluid suction path, 12...Fluid discharge path, 15...Pump housing inner peripheral surface, work 8...Pivot recess, 2
DESCRIPTION OF SYMBOLS 1... Inner circumferential surface of cam ring, 22... Outer circumferential surface of cam ring, 23... Pivot part, 25... Cam spring, 32... Outer circumferential surface of rotor, 73... Throttle part, 91
...First control pressure chamber, 92...Second control pressure chamber, 03...Center of cam ring, α...
The axis of rotation of the rotor.

Claims (1)

[Claims] 1. A pump housing having a fluid suction passage and a fluid discharge passage, a cam ring provided within this pump housing, a rotor provided within this cam ring that is rotationally driven, and a rotor that moves forward and backward in the radial direction on the outer circumference of this rotor. a plurality of vanes that are movable and whose radially outer ends are in sliding contact with the inner circumferential surface of the cam ring; The housing is swingably supported by the housing and biased in the direction of increasing the amount of eccentricity by the spring force of a cam spring, and by rotating the rotor, fluid passes through the fluid suction path and is applied to the inner circumferential surface of the cam ring. and the outer circumferential surface of the rotor, and is discharged from the space through the fluid discharge path,
In the variable displacement vane pump, the eccentricity of the cam ring is controlled according to the amount of fluid discharged from the fluid discharge passage, and the discharge amount is changed according to the eccentricity of the cam ring. A pivot portion is integrally formed to protrude from a portion of the outer peripheral surface, a pivot recess is formed in a portion of the inner peripheral surface of the pump housing, and the pivot portion is rotatably fitted into the pivot recess. By this, the cam ring is swingably supported, and fluid pressure is introduced into the space between the inner circumferential surface of the pump housing and the outer circumferential surface of the cam ring, and the cam ring is eccentrically moved by the fluid pressure. A first control pressure chamber biasing the cam ring in the direction of decreasing eccentricity, and a second control pressure chamber into which fluid pressure is introduced and biasing the cam ring in the direction of increasing the eccentricity are formed. A communication passage is provided in the section to communicate the fluid discharge passage with the space between the inner peripheral surface of the cam ring and the outer peripheral surface of the rotor, and a constriction part is provided in the middle of the communication passage, and a constriction part is provided in the middle of the constriction part. The variable capacity type is configured such that fluid pressure on the downstream side of the constriction part is introduced into the first control pressure chamber, and fluid pressure on the downstream side of the throttle part is introduced into the second control pressure chamber. vane pump.