JP2870600B2 - Variable displacement vane pump - Google Patents

Description

Description: 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 for an automatic transmission of an automobile, for example.

[Conventional technology]

Conventionally, as this kind of variable displacement vane pump,
For example, one disclosed in Japanese Utility Model Publication No. 63-19597 is known.

This conventional pump includes a pump housing having a fluid suction passage and a fluid discharge passage, a cam ring (oscillating ring) provided in the pump housing, a rotor provided in the cam ring and driven to rotate, A plurality of vanes are provided on the outer peripheral portion of the rotor so as to be able to advance and retreat in the radial direction, and the outer ends in the radial direction are in sliding contact with the inner peripheral surface of the cam ring. The cam ring is swingably supported via a support pin by the pump housing so that the center thereof can be eccentric with respect to the rotation axis of the rotor, and the direction of increase in the amount of eccentricity by the spring force of the cam spring. Has been energized.

With this configuration, the conventional pump rotates the rotor to suck fluid 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 to discharge the fluid. The fluid can be discharged from the passage, and the discharge amount of the fluid from the fluid discharge passage can be changed according to the eccentric amount of the cam ring. Also, this conventional pump,
The cam ring is configured to control the amount of eccentricity according to the amount of discharge, so that a discharge amount characteristic as shown in FIG. 5, for example, can be obtained.

[Problems to be solved by the invention]

In the above-described conventional pump, the following configuration is used to control the amount of eccentricity of the cam ring in accordance with the discharge amount.

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

As described above, in the configuration of the conventional pump, in order to control the eccentric amount of the cam ring according to the discharge amount, a flow control valve having a spool that requires high-precision processing is used,
Cost was up.

In view of the above circumstances, an object of the present invention is to provide a variable displacement vane pump that can control the amount of eccentricity of a cam ring in accordance with a discharge amount with an inexpensive configuration.

[Means for solving the problem]

A variable displacement vane pump according to the present invention includes: a pump housing having a fluid suction passage and a fluid discharge passage; a cam ring provided in the pump housing; a rotor provided in the cam ring and driven to rotate; A plurality of vanes which are provided on the outer peripheral portion of the cam ring so as to be able to advance and retreat in the radial direction, and whose radially outer end is in sliding contact with the inner peripheral surface of the cam ring, wherein the cam ring has a center with respect to the rotation axis of the rotor. The pump housing is swingably supported by the pump housing so as to be eccentric, and is urged in a direction of increasing the amount of eccentricity by a spring force of a cam spring. By rotating the rotor, fluid flows through the fluid suction passage. And is sucked into a space between the inner peripheral surface of the cam ring and the outer peripheral surface of the rotor, and passes through the fluid discharge passage from the space. And the eccentric amount of the cam ring is controlled in accordance with the amount of fluid discharged from the fluid discharge path, and the discharge amount is changed in accordance with the eccentric amount of the cam ring. A first control pressure chamber in which a fluid pressure is introduced into a space between an inner peripheral surface of the pump housing and an outer peripheral surface of the cam ring, and the fluid pressure urges the cam ring in a direction of decreasing the amount of eccentricity; A second control pressure chamber is formed for introducing the fluid pressure and for urging the cam ring in the direction of increasing the eccentricity by the fluid pressure, and a space portion between the inner peripheral surface of the cam ring and the outer peripheral surface of the rotor is formed. A communication passage communicating with the control pressure chamber is provided, and a throttle portion is provided in the communication passage. The fluid pressure upstream of the throttle portion is controlled by the first control pressure. A fluid pressure introduction passage for introducing the fluid into the chamber is provided, and the fluid discharge passage is opened to the second control pressure chamber, so that a fluid in a space portion between an inner peripheral surface of the pump housing and an outer peripheral surface of the cam ring is supplied. It is configured to be guided to the second control pressure chamber and then discharged through the fluid discharge path.

[Action]

According to the above configuration, a pressure difference occurs before and after the throttle portion provided in the communication passage, and the second control pressure chamber downstream of the throttle portion has a fluid pressure lower than the fluid pressure upstream of the throttle portion. Is introduced. On the other hand, the fluid pressure on the upstream side of the throttle section is introduced into the first control pressure chamber via the fluid pressure introduction passage.
The high fluid pressure upstream of the throttle portion introduced into the first control pressure chamber urges the cam ring in the direction of decreasing the amount of eccentricity, and the low fluid pressure downstream of the throttle portion introduced into the second control pressure chamber. The pressure urges the cam ring in the direction of increasing the eccentricity. Therefore, the differential pressure between the high and low fluid pressures acts on the cam ring against the spring force of the cam spring, and the eccentric amount of the cam ring is controlled by the force relationship between the differential pressure and the spring force. . That is,
The eccentric amount of the cam ring is controlled according to the differential pressure. In addition, since the differential pressure changes according to the flow rate (discharge amount) passing through the throttle unit, the eccentric amount of the cam ring is controlled according to the discharge amount.

〔Example〕

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

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

The pump housing 1 includes a housing main body 1a and a cover-side housing 1b. A cylindrical concave portion having one end opened at the center of the housing main body 1a is formed. It is closed to form the housing lumen 1c. A fluid suction passage 11 and a fluid discharge portion 12 are formed through the housing body 1a. One end of each of the fluid suction passage 11 and the fluid discharge passage 12 is opened to an outer peripheral flange portion of the housing body 1a, and a suction port 11a is formed. And a discharge port 12a. In addition,
Part of the fluid suction passage 11 is also formed in the cover-side housing 1b.

The cam ring 2 has a circular inner peripheral surface 21 and is provided in the housing cavity 1c in such a manner that both side surfaces thereof are in close contact with the pump housing inner surfaces 13, 14 facing the housing cavity 1c.

The rotor 3 is formed with a smaller diameter than the circular inner peripheral surface 21 of the cam ring 2, and is provided in the circular inner peripheral surface 21 of the cam ring 2 with both side surfaces being in close contact with the pump housing inner side surfaces 13 and 14, respectively. . The rotor 3 is connected to a rotor drive shaft (not shown) inserted through the cover-side housing 1b via a drive flange 3a, thereby forming a housing cavity 1c.
₁ rotates around the axis α of the rotor drive shaft passing through the center O1 of the peripheral surface (the inner peripheral surface of the pump housing) 15 of FIG.

A plurality of vane grooves 31 are radially formed on the outer periphery of the rotor 3. Each vane groove 31 is open to the rotor outer peripheral surface 32, and the vane 4 is fitted in each vane groove 31 so as to be able to advance and retreat in the rotor radial direction.

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

The vane 4 is urged outward in the rotor radial direction by the guide ring 35 and centrifugal force caused by the rotation of the rotor 3,
The outer end in the radial direction is constantly pressed against the circular inner peripheral surface 21 of the cam ring 2 so as to slide on the circular inner peripheral surface 21.

Outer peripheral surface 22 of cam ring 2 and inner peripheral surface 15 of pump housing
Are formed with semicircular concave portions 23a and 18 facing each other. A cylindrical pivot roller 23 is provided between these concave portions 23a, 18 with its outer peripheral surface abutting on the inner peripheral surface of each concave portion 23a, 18, and the cam ring 2 is pivotally connected to the pump housing 1. The roller 23 is swingably supported in the directions of arrows A and B in FIG. 1 around the center O _{2 of the} roller 23 (the pivot point). Thereby, the center O ₃ of the cam ring 2 (the center of the circular inner peripheral surface 21) can be eccentric with respect to the rotation axis α of the rotor 3. Incidentally, it is set to be equal to the distance from the distance and the pivot point O ₂ from pivot point O ₂ to the rotation axis α of the rotor 3 to the center O ₃ of the cam ring 2.

In the outer peripheral surface 22 of the cam ring 2, pivot point O ₂ and the cam ring 2
On one side of the center line β passing through the center O _{3 of}
A spring seat 24 is formed to protrude. The spring seat 24 is provided with the cam ring 2 in the direction of increasing the eccentricity (first direction).
The spring force of the cam spring 25 biasing in the direction indicated by the arrow B in the drawing is applied, whereby the cam ring 2 is pressed to the maximum eccentric position.

On the other side of the outer peripheral surface 22 of the cam ring 2 which is separated from the center line β, a stopper surface 26 is formed which abuts on the inner peripheral surface 15 of the pump housing at the maximum eccentric position of the cam ring 2 to stop the movement of the cam ring 2. Have been.

On the outer peripheral portion of the cam ring 2, first and second portions extending in the radial direction of the cam ring 2 at equal intervals from the pivot roller 23 on one side and the other side with respect to the center line β.
Seal grooves 27 and 28 are formed. The first and second seal grooves 27 and 28 are respectively opened in the outer peripheral surface 22 of the cam ring, and the first and second seal grooves 27 and 28 are respectively provided with first and second plate-shaped seal members 51 and 52 respectively. It is fitted so that it can advance and retreat in the radial direction.

The space between the pump housing inner peripheral surface 15 and the cam ring outer peripheral surface 22 is formed by the first and second seal members 52, 52.
And the pivot roller 23 divides it into three parts.
A first controller pressure chamber between the first seal member 51 and the first seal member 51;
91, a second controller pressure chamber 92 is formed between the pivot roller 23 and the second seal member 52, and a drain chamber 93 is formed between the first seal member 51 and the second seal member 52, respectively.

Fluid pressure is introduced into the first and second control pressure chambers 91 and 92, respectively, as described later. The first control pressure chamber 91 urges the cam ring 2 in the direction of decreasing the amount of eccentricity by the introduced fluid pressure. , Second control pressure chamber 92
Is adapted to urge the cam ring 2 in the direction of increasing the amount of eccentricity by the introduced fluid pressure. Also, the drain room 93
, The other end of the fluid suction passage 11 is open, and the other end of the fluid discharge passage 12 is open to the second control pressure chamber 92.

The pivot roller 23 is provided in a state where both side surfaces are in close contact with the pump housing inner side surfaces 13 and 14, respectively. Therefore, the pivot roller 23 is provided with a sealing function, and the pivot roller 23 reliably seals between the first control pressure chamber 91 and the second control pressure chamber 92.

As shown in FIG. 4, back pressure chambers 27a and 28a are provided at radially inner ends of the seal grooves 27 and 28, respectively.
The fluid pressure in the corresponding control pressure chambers 91, 92 is introduced into 8a via the back pressure introduction paths 27b, 28b, respectively. Each of the seal members 51 and 52 receives the fluid pressure introduced into each of the back pressure chambers 27a and 28a at its radially inner end, and the radially outer end is constantly pressed against the pump housing inner peripheral surface 15 by the fluid pressure. Have been. Therefore, the first control pressure chamber 91 is formed by the seal members 51 and 52.
And the drain chamber 93 and between the second control pressure chamber 92 and the drain chamber 93 are securely sealed.

The space surrounded by the inner peripheral surface 21 of the cam ring 2, the outer peripheral surface 32 of the rotor 3, and the inner surfaces 13 and 14 of the pump housing is divided into a plurality of parts by the vane 4. A chamber 6 is formed. Since the center O _{3 of the} cam ring 2 is eccentric with respect to the rotation axis α of the rotor 3, the volume of each pump chamber 6 increases and decreases with the rotation of the rotor 3.

A suction groove 94 and a discharge groove 95 are formed on the inner surface 13 of the pump housing 1. The suction groove 94 communicates with the fluid suction passage 11 and opens to the pump chamber 6a in the process of increasing the volume, and the opening forms a suction port 94a. On the other hand, the discharge groove 95 is formed at the position of the pump chamber 6b in the process of reducing the volume.
Make up a.

As shown in FIG. 3, the pump chamber 6b and the second control pressure chamber 92 communicate with the portion of the cam ring 2 located between the pump chamber 6b in the process of reducing the volume and the second control pressure chamber 92. A communication passage 7 is formed to penetrate. A throttle (orifice) 73 is provided at an opening of the communication passage 7 on the pump chamber 6b side. A part of the discharge groove 95 is moved from the position of the pump chamber 6b during the volume reduction process to the first control pressure chamber.
It extends to the position 91 and opens to the pressure chamber 91, and constitutes a fluid pressure introduction passage 95b for introducing the fluid pressure in the pump chamber 6b in the process of reducing the volume upstream of the throttle portion 73 to the first control pressure chamber 91. The passage cross-sectional area of the fluid pressure introduction passage 95b is:
It is set to be several times larger than the passage cross-sectional area of the throttle portion 73.

In the above configuration, when the rotor 3 is rotated in the direction of arrow C from the state of FIG. 1 (the state in which the cam ring 2 is maximally eccentric), each pump chamber 6 also rotates and moves in the direction of arrow C while repeatedly increasing and decreasing the volume. . And each pump room 6
In the process of increasing the volume, the fluid such as oil guided to the suction port 94a through the fluid suction passage 11 from the suction port 11a is communicated with the suction port 94a in the process of increasing the volume. The suctioned fluid is discharged in communication with the discharge port 95a and the communication path 7. The fluid discharged toward the discharge port 95a is supplied to the fluid pressure introduction path 95b.
The fluid introduced into the first control pressure chamber 91 through the communication passage 7 and discharged toward the communication passage 7 passes through the communication passage 7 to the second control pressure chamber 91.
After being guided to the control pressure chamber 92, it is guided to the fluid discharge part 12 and discharged from the discharge port 12a.

By the way, in this pump, a restricting portion is
73 are provided. For this reason, a differential pressure is generated before and after the throttle portion 73, and the second control pressure chamber 92 downstream of the throttle portion 73 has:
Fluid pressure P ₂ of reduced relative to the fluid pressure P ₁ of the aperture section 73 upstream is introduced. On the other hand, high fluid pressure P ₁ on the upstream side of the throttle portion 73 is introduced into the first control pressure chamber 91 via the fluid pressure introducing passage 95b. Thereby, in addition to the spring force F of the cam spring 25 acting on the cam ring 2 in the increasing direction of the eccentric amount,
High fluid pressure P ₁ is applied in the decreasing direction of eccentricity, so that low fluid pressure P ₂ is applied in an increasing direction of the eccentricity. That is, the differential pressure ΔP between the high fluid pressure P ₁ and the low fluid pressure P ₂ is applied to the cam ring 2.
(= P ₁ −P ₂ ) acts against the spring force F of the cam spring 25.

The differential pressure ΔP is the flow rate (discharge amount) passing through the throttle unit 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 rotation 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 exceeds the force acting on the cam ring 2 due to the differential pressure ΔP, and 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, when 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 so as to balance the force due to the differential pressure ΔP when the discharge amount Q reaches the predetermined amount Q ₀ , the rotation speed N of the rotor 3 increases. Te, the discharge amount Q reaches a predetermined amount Q _0, the force due to the differential pressure ΔP cam spring
By overcoming the spring force F of 25, the cam ring 2 swings in the direction of decreasing the amount of eccentricity. As a result, the amount of eccentricity of the cam ring 2 decreases, the displacement decreases, and the discharge amount Q
Is maintained so as not to exceed a predetermined amount Q ₀ .

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, can also speed N is increased discharge amount Q controls the discharge quantity Q so as not to exceed a certain amount Q _0. Moreover, the discharge amount characteristic as shown in FIG. 5 can be obtained without using a flow control valve having a spool or the like, and can be achieved at low cost.

In the above embodiment, the fluid suction passage 11 is directly connected to the suction port 94a while bypassing the space between the pump housing inner peripheral surface 15 and the cam ring outer peripheral surface 22. At a position substantially opposite to the pivot roller 23 with respect to the cam ring outer peripheral surface 22, a cylindrical seal member is interposed while being held by the housing body 1a. The space between the inner peripheral surface 15 of the pump housing and the outer peripheral surface 22 of the cam ring is divided into two parts by the seal member and the pivot roller 23, and a first control pressure chamber 91 is provided on one side (eccentric side of the cam ring). Alternatively, a second control pressure chamber 92 may be provided on the other side. By doing so, the drain chamber 93 is not required, and the number of seal members can be reduced. Further, in the above embodiment, a pivot portion corresponding to the pivot roller 23 may be integrally formed on a part of the outer peripheral surface 22 of the cam ring. Further, the communication passage 7 may be formed in the pump housing 1 or the fluid pressure introduction passage 95b may be formed to penetrate the cam ring 2.

〔The invention's effect〕

In the variable displacement vane pump according to the present invention, a fluid pressure is introduced into a space between the inner peripheral surface of the pump housing and the outer peripheral surface of the cam ring, and the cam pressure is urged in the direction of decreasing the eccentricity by the fluid pressure. (1) a control pressure chamber, and a second control pressure chamber for introducing a fluid pressure and biasing the cam ring in the direction of increasing the eccentricity by the fluid pressure, and a space portion between the inner peripheral surface of the cam ring and the outer peripheral surface of the rotor. A communication path is provided for communicating between the communication path and the second control pressure chamber, a throttle section is provided in the communication path, and a fluid pressure introduction path for introducing fluid pressure upstream of the throttle section to the first control pressure chamber is provided. ing. Therefore, the eccentric amount of the cam ring can be controlled according to the discharge amount without using a flow control valve having a spool or the like, and an inexpensive variable displacement vane pump that does not require a flow control valve can be configured.

In addition, since the throttle portion is provided in the communication path that communicates the space between the inner peripheral surface of the cam ring and the outer peripheral surface of the rotor and the second control pressure chamber, the fluid pressure downstream of the throttle portion is supplied to the second control pressure chamber. There is no need to provide a fluid pressure introduction path for introduction.

[Brief description of the drawings]

FIG. 1 is a front view showing one embodiment of a variable displacement vane pump according to the present invention except for a cover side housing, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. III-III
FIG. 4 is a sectional view taken along the line IV-IV of FIG. 1, and FIG. 5 is a graph showing the relationship between the number of rotations of the rotor and the discharge amount. DESCRIPTION OF SYMBOLS 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, 21 ... cam ring inner peripheral surface, 22 ... cam ring outer peripheral surface, 25 ... cam spring, 32 ... rotor outer peripheral surface, 73 ...
... throttle section, 91 ... first control pressure chamber, 92 ... second
Control pressure chamber, 95b ...... fluid pressure introduction path, O ₃ center ...... cam ring, the axis of rotation of the alpha ...... rotor.

Claims (1)

(57) [Claims] 1. A pump housing having a fluid suction passage and a fluid discharge passage, a cam ring provided in the pump housing, a rotor provided in the cam ring and driven to rotate, and a radius around an outer peripheral portion of the rotor. A plurality of vanes provided so as to be able to advance and retreat in the direction, and having a radially outer end slidingly contacting the inner peripheral surface of the cam ring, wherein the cam ring has a center that can be eccentric with respect to the rotation axis of the rotor. The pump ring is swingably supported by the pump housing, and is urged in a direction of increasing the eccentricity by a spring force of a cam spring. When the rotor is rotated, fluid passes through the fluid suction passage to form the cam ring. The fluid is sucked into a space between the inner peripheral surface and the outer peripheral surface of the rotor, is discharged from the space through the fluid discharge passage, and An eccentric amount of the cam ring is controlled in accordance with a discharge amount of fluid from an outlet, and the discharge amount changes in accordance with the eccentric amount of the cam ring. In the space between the outer peripheral surface of the cam ring and
A first control pressure chamber in which fluid pressure is introduced and biases the cam ring in the direction of decreasing the eccentricity by the fluid pressure; and a first control pressure chamber in which fluid pressure is introduced and biases the cam ring in the direction of increasing the eccentricity by the fluid pressure. A second control pressure chamber is formed, and a communication path communicating the space between the inner peripheral surface of the cam ring and the outer peripheral surface of the rotor and the second control pressure chamber is provided, and a throttle portion is provided in the communication path. A fluid pressure introduction passage for introducing fluid pressure on the upstream side of the throttle section into the first control pressure chamber;
The fluid discharge passage is opened to the control pressure chamber, and the fluid in the space between the inner peripheral surface of the pump housing and the outer peripheral surface of the cam ring is guided to the second control pressure chamber, and then the fluid discharge passage is opened. A variable displacement vane pump configured to be discharged through the pump.