JP2000265977A - Variable displacement pump - Google Patents

Abstract

(57) [Summary] In a variable displacement pump, the clearance between a rotor and a side plate on a pump housing side is narrowed so that a discharge fluid in a pump chamber effectively acts on the back of a vane, and a rotor and a side plate are formed. To improve seizure performance and prevent seizure. SOLUTION: In a variable displacement pump 10, a seal member 71 is provided at a fixed portion between a pump shaft 12 and a rotor 13,
Discharge side pressure chamber 2 from which pressure fluid is discharged from pump chamber 23
A high pressure oil circulation path 70 that connects 8A to the base side surface of the rotor 13 via the outer periphery of the pump shaft 12 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement pump used for a power steering device of an automobile.

[0002]

2. Description of the Related Art Conventionally, a variable displacement pump as disclosed in Japanese Patent Application Laid-Open No. 9-166094 has been proposed for assisting a steering force by a hydraulic power steering device of an automobile. This conventional variable displacement pump is directly driven to rotate by an automobile engine, and a rotor is provided in a cam ring fitted to the pump housing so as to be movable and displaced. A pump chamber is formed.

In this prior art, the cam ring is made movable within the pump housing, and an urging force for maximizing the volume of the pump chamber is applied to the cam ring. The first and second fluid pressure chambers are formed separately, and the pressure before the orifice provided in the discharge passage of the pressure fluid discharged from the pump chamber is applied to the first fluid pressure chamber, and the pressure after the orifice is applied to the second fluid pressure chamber. And a cam ring is moved in contact with the urging force by a pressure difference between the pressures acting on the two fluid pressure chambers, thereby changing a volume of the pump chamber to control a discharge flow rate. . Thus, in this variable displacement pump, the discharge flow rate is increased so that a large steering assist force can be obtained when the vehicle having a low rotation speed is stopped or running at low speed.
During high-speed running at a high rotational speed, the discharge flow rate is controlled to a certain value or less so as to reduce the steering assist force, so that the steering assist force required for the power steering device can be generated.

In this prior art, there is provided a vane pressurizing device for guiding a pressurized fluid discharged from a pump chamber to a base of a groove accommodating a vane of a rotor and pressurizing the vane toward a cam ring. I have. Thus, in this variable displacement pump, the vane is pressed against the cam ring by centrifugal force at the beginning of rotation, but after the discharge pressure is generated,
This discharge fluid is guided to the base of the vane accommodating groove (the back of the vane) so as to have a vane back pressure to increase the contact pressure between the vane and the cam ring, thereby preventing the backflow of the pressurized fluid.

[0005]

In the prior art having the vane pressurizing device, it is necessary to make the fluid discharged from the pump chamber effectively act on the back of the vane, so that the side plates of the rotor and the vane and the side plate on the pump housing side. It is necessary to reduce the clearance between the two as much as possible. However, when the above-mentioned clearance is simply narrowed, there is a possibility that insufficient lubrication may occur between the rotor and the side plate and seizure of the rotor and the side plate may occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a variable displacement pump in which the clearance between the rotor and the side plate on the pump housing side is narrowed so that the discharge fluid in the pump chamber effectively acts on the back of the vane. The purpose of the present invention is to improve the lubrication performance of the device and prevent seizure.

[0007]

According to the first aspect of the present invention, the pump is fixed to a pump shaft inserted into a pump housing, is driven to rotate, and moves in a radial direction by accommodating a large number of vanes in a groove. A rotatable rotor, a cam ring fitted to the pump housing and forming a pump chamber between the outer periphery of the rotor, and a cam ring that can be displaced within the pump housing and maximizes the volume of the pump chamber. And the first and second fluid pressure chambers are divided between the cam ring and the pump housing, and are provided before the orifice provided in the discharge passage of the pressure fluid discharged from the pump chamber. The pressure is led to the first fluid pressure chamber, the pressure after the orifice is led to the second fluid pressure chamber, and the cam ring is moved against the urging force by the pressure difference between the two pressure chambers. And a discharge flow control device capable of controlling the discharge flow rate by changing the volume of the pump chamber, and guiding the pressure fluid discharged from the pump chamber to the base of the groove accommodating the vane of the rotor, and guiding the vane to the cam ring. In a variable displacement pump having a vane pressurizing device that pressurizes toward, a sealing material is provided on a fixed portion between the pump shaft and the rotor,
A high-pressure oil circulation path is provided that connects the discharge-side pressure chamber, from which the pressure fluid is discharged from the pump chamber, to the base side surface of the rotor via the outer periphery of the pump shaft.

According to a second aspect of the present invention, in the first aspect of the present invention, a low-pressure oil circulation system further includes connecting a suction passage for guiding a suction-side fluid to the pump chamber to a side surface of a base of the rotor via an outer periphery of a pump shaft. A road is provided.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the pump housing is further provided with a first housing.
The housing and the second housing are combined,
The pump shaft extends through the second housing and is inserted into the first housing. The first housing houses a first bearing, a rotor, a cam ring, and a vane for the pump shaft, and has a discharge-side pressure chamber. The second housing accommodates a second bearing and an oil sheet for the pump shaft.

[0010]

According to the first aspect of the present invention, the following operations are provided. Since the high pressure oil circulation path guides the pressure fluid discharged from the pump chamber to the base side surface of the rotor, the high pressure oil can be supplied to the clearance between the rotor and the discharge side plate to improve the lubrication performance thereof. Therefore, seizure of the rotor and the side plate can be prevented while narrowing the clearance between the rotor and the side plate so that the discharge fluid of the pump chamber effectively acts on the back of the vane.

[0011] A seal member is provided at a fixed portion between the pump chamber and the rotor. Therefore, in a state in which the high-pressure oil circulation path is provided on the side surface of the base of the rotor, the high-pressure oil can be prevented from leaking, and the high-pressure oil can be effectively supplied to the clearance between the rotor and the discharge side plate.

According to the second aspect of the present invention, the following operations are provided. The low-pressure oil circulation path circulates the suction side fluid to the pump chamber from the suction port side to the suction passage through the clearance between the rotor and the suction side plate, improving the lubrication performance of the rotor and the suction side plate. I can make it. Therefore, seizure of the rotor and the side plate can be prevented while the clearance between the rotor and the side plate is further narrowed so that the discharge fluid of the pump chamber effectively acts on the base of the vane.

According to the third aspect of the present invention, the following operations are provided. Since the discharge-side pressure chamber and the high-pressure oil circulation path are formed on the first housing side, the oil seal through which the pump shaft passes in the second housing only needs to seal the low-pressure oil in the low-pressure side circulation path, and the sealing performance can be improved. .

[0014]

1 is a sectional view showing a variable displacement pump, and FIG. 2 is a sectional view taken along the line II-II of FIG.

The variable displacement pump 10 is a vane pump serving as a hydraulic pressure source for a hydraulic power steering device of an automobile. As shown in FIGS.
And a rotor 13 which is fixed by serration to a pump shaft 12 inserted therein and is driven to rotate. The pump housing 11 is configured by integrating a first housing 11A and a second housing 11B with bolts 14, and supports a pump shaft 12 via a first bearing 15A and a second bearing 15B. The pump shaft 12 can be directly driven to rotate by an automobile engine.

The pump shaft 12 is connected to the second housing 11B.
Is inserted into the first housing 11A, and a first bearing 15 for the pump shaft 12 is provided on the side of the first housing 11A.
A, the rotor 13, a vane 17, a discharge-side side plate 18, an adapter ring 19, a suction-side side plate 20, and a cam ring 22 are accommodated, and a discharge-side pressure chamber 28A described later is formed.
Is provided with a second bearing 15B and an oil seal 15C for the pump shaft 12.

The rotor 13 accommodates vanes 17 in grooves 16 provided at a plurality of positions in the circumferential direction, and enables each vane 17 to move in a radial direction along the grooves 16.

First housing 1 of pump housing 11
1A, a discharge side plate 18, an adapter ring 19, and a suction side plate 20 are fitted in a stacked state, and these three members are positioned in a circumferential direction by a fulcrum pin 21 described later in the second housing 11B. Is fixedly held from the side. One end of the fulcrum pin 21 is mounted and fixed to the second housing 11B.

A cam ring 22 is fitted on the adapter ring 19 fixed to the pump housing 11. The cam ring 22 surrounds the rotor 13 with a certain amount of eccentricity with the rotor 13, and forms a pump chamber 23 between the cam ring 22 and the outer peripheral portion of the rotor 13. A suction port 24 provided in the side plate 20 is opened on the upstream side of the pump chamber 23 in the direction of rotor rotation, and the suction port 24 is connected to the suction port 2 through a suction passage 25 provided in the second housing 11B.
6 is communicated. On the other hand, a discharge port 27 provided in the side plate 18 is opened on the downstream side in the rotor rotation direction of the pump chamber 23. The discharge port 27 is provided with a discharge-side pressure chamber 28A and a discharge passage 28B provided in the first housing 11A. The discharge port 29 is communicated through the intermediary.

Thus, in the variable displacement pump 10, the rotor 13 is driven to rotate by the pump shaft 12,
When the vane 17 of the rotor 13 rotates by being pressed against the cam ring 22 by centrifugal force, the rotor 13 and the vane 17
Are in sliding contact with the side plates 18 and 20 on both sides, and the adjacent vanes 1 are located downstream of the pump chamber 23 in the rotor rotation direction.
The working fluid is sucked from the suction port 24 by expanding the volume surrounded by the cam ring 22 and the space between the cam ring 22 and the pump chamber 2.
On the upstream side in the rotor rotation direction 3, the volume enclosed between the adjacent gates 17 and the cam ring 22 is reduced with rotation and the working fluid is discharged from the discharge port 27.

However, the variable displacement pump 10 has the following
It has a discharge flow control device 40 as shown in (A) and a vane pressurizing device 60 as shown in (B) below.

(A) Discharge flow rate control device 40 The discharge flow rate control device 40 mounts the above-mentioned fulcrum pin 21 on the vertically uppermost part of the above-mentioned adapter ring 19 fixed to the pump housing 11, The uppermost portion is supported by the fulcrum pin 21, and the cam ring 22 is swingably displaceable within the adapter ring 19. And
The discharge flow control device 40 applies an urging force that maximizes the volume of the pump chamber 23 by the pressurizing plunger 43 that is supported on the back by a spring 42 that is backed up by a cap 41 that is screwed to the first housing 11A. It can be applied to the cam ring 22.

The discharge flow control device 40 has first and second fluid pressure chambers 44A and 44B divided between the cam ring 22 and the adapter ring 19. That is, the first fluid pressure chamber 44A and the second fluid pressure chamber 44B
And the adapter ring 19 are divided by the fulcrum pin 21 and the sealing material 45 provided at the axially symmetric position.

The discharge flow control device 40 has an orifice 46 in the middle of the discharge passage 28B for the pressurized fluid discharged from the pump chamber 23. The opening area of the orifice 46 is adjusted by the pressurizing plunger 43 described above. The throttle valve body 43A is partially cut off and variable. Then, the discharge flow control device 40 applies the high fluid pressure before passing through the orifice 46 to the first fluid pressure supply path 47A, the switching valve 48,
9 to the first fluid pressure chamber 44A and the orifice 4
After the passage through the passage 6, the reduced pressure is guided to the second fluid pressure chamber 44B via the second fluid pressure supply passage 47B, and the two fluid pressure chambers 44A, 44B
The cam ring 22 is moved against the urging force of the pressure plunger 43 by the pressure difference acting on the pump plunger 43 to change the volume of the pump chamber 23 so that the discharge flow rate of the pump 10 can be controlled.

The switching valve 48 is connected to the first housing 11A.
A cap 52 in which a spring 52 and a switching plunger 53 are accommodated in a valve storage hole 51 formed in the first housing 11A and the plunger 53 urged by the spring 52 is screwed to the first housing 11A.
4 carried. The switching plunger 53 includes upper, middle, lower
Each of the positions is provided with an upper valve body 55A, a switching valve body 55B, and a lower valve body 55C, and a first fluid pressure supply passage 47A communicates with an upper chamber 56A between the upper valve body 55A and the switching valve body 55B. The second fluid pressure supply path 47B is connected to a back pressure chamber 56B in which the spring 52 below the valve body 55C is stored through a communication path 57A having an orifice 57. In a low rotation range where the discharge pressure of the pump 10 is low, the spring 5
The switching plunger 53 is set to the original position shown in FIG. 1 by the urging force of 2, and the first fluid pressure chamber 44A is switched by the switching valve body 55B.
And in the middle and high rotation region of the pump 10, the high pressure fluid added to the upper chamber 56A causes the switching plunger 5 to move.
3 is moved to open the communication passage 49, and the high-pressure fluid is
It is possible to guide to the fluid pressure chamber 44A.

Accordingly, the discharge flow characteristics of the pump 10 provided with the discharge flow control device 40 are as follows.

(1) In a low-speed running range of an automobile where the rotation speed of the pump 10 is low, the switching valve 48 is discharged from the pump chamber 23 and
The pressure of the fluid reaching the upper chamber 56A is still low, and the switching valve 48
Is located at the original position, and the cam ring 22 is
3. Maintain the original state energized by 3. Therefore, the discharge flow rate of the pump 10 increases in proportion to the rotation speed.

(2) When the pressure of the fluid discharged from the pump chamber 23 and reaching the upper chamber 56A of the switching valve 48 increases due to an increase in the rotation speed of the pump 10, the switching valve 48
The switching plunger 53 is moved against the urging force of No. 2 to open the communication passage 49 and guide this high-pressure fluid to the first fluid pressure chamber 44A. As a result, the cam ring 22 is connected to the first fluid pressure chamber 44.
The pump chamber 23 is moved by the pressure difference between the pressure acting on the second fluid pressure chamber 44B and the pressure acting on the second fluid pressure chamber 44B, and the volume of the pump chamber 23 is gradually reduced. Therefore, the discharge flow rate of the pump 10 increases as the rotation speed increases.
An increase in the flow rate due to an increase in the number of revolutions and a decrease in the flow rate due to a reduction in the volume of the pump chamber 23 can be offset to maintain a constant large flow rate.

(3) When the number of revolutions of the pump 10 continues to further increase and the cam ring 22 moves further, and the cam ring 22 pushes the pressure plunger 43 beyond a certain amount, the pressure plunger 43 is throttled. The valve element 43A starts to reduce the opening area of the orifice 46 at the intermediate portion of the discharge passage 28A from the pump chamber 23. Therefore, the discharge flow rate of the pump 10 decreases in proportion to the amount of restriction of the orifice 46 by the restrictor valve body 43A of the pressurizing plunger 43.

(4) When the rotation speed of the pump 10 reaches a high-speed driving range of the automobile exceeding a certain value, the cam ring 22 reaches the limit of movement, and the throttle amount of the orifice 46 by the throttle valve body 43A of the pressurizing plunger 43 also becomes maximum. And the discharge flow rate of the pump 10 maintains a constant small flow rate.

(B) Vane pressurizing device 60 The vane pressurizing device 60 is provided with the grooves 16 of the side plate 18 and the side plate 20 corresponding to both sides of the base 16A of the groove 16 accommodating the vane 17 of the rotor 13. Are provided with ring-shaped oil grooves 61 and 62 on the sliding contact surface of the roller. And the first
The discharge-side pressure chamber 28A of the pump chamber 23 provided in the housing 11A communicates with the above-described oil groove 61 via an oil hole 63 provided in the side plate 18. As a result, the pressure fluid discharged from the pump chamber 23 to the discharge-side pressure chamber 28A is transferred to the oil grooves 6 of the side plates 18 and 20.
Via the first and the second 62, it is guided to the base of the groove 16 for all the vanes 17 in the circumferential direction of the rotor 13, and each vane 17 can be pressed toward the cam ring 22.

Thus, in the pump 10, the vane 17 is pressed against the cam ring 22 by centrifugal force at the beginning of rotation, but after the discharge pressure is generated, the vane 17 and the cam ring 22 are The contact pressure is increased, and the backflow of the pressure fluid can be prevented.

However, in the variable displacement pump 10, as described below, the high pressure oil circulation path 70 and the low pressure oil circulation path 8
0.

(High-pressure oil circulation path 70) The rotor 13 is provided with a loading portion 72 for a sealing material 71 such as an O-ring on the discharge side end surface of the inner peripheral portion mounted on the pump shaft 12.
The seal member 71 is interposed in this fixed portion between the rotor and the rotor 13.

The first housing 11A has a discharge side pressure chamber 28A and a first bearing 15A for supporting the pump shaft 12.
A high-pressure oil communication path 74 that connects them to the closed end side of the bearing chamber 73 is formed to form a high-pressure oil circulation path 70 as a result. The high-pressure oil circulation path 70
From the discharge side pressure chamber 28A of the pump chamber 23 to the high pressure oil communication path 7
4. Bearing chamber 73, outer periphery of pump shaft 12 (first bearing 15
A), and constitutes a high-pressure lubricating oil supply system which reaches the base side surface of the rotor 13 via the rotor 13 and returns to the discharge side pressure chamber 28A via the discharge port 27 and the clearance between the rotor 13 and the side plate 18. The lubrication performance in the sliding contact area between the side plate 13 and the side plate 18 is improved.

O-rings 75 and 76 are interposed between the first housing 11A and the side plate 18.

(Low-pressure oil circulation path 80) Second housing 11
B is a low-pressure oil communication path 82 that connects the suction passage 25 to the base side surface of the rotor 13 through a shaft insertion space 81 formed on the outer periphery of the pump shaft 12 inside the oil seal 15C mounted on the pump shaft 12. The low pressure oil circulation path 80 is configured as a result. Low pressure oil circuit 80
Reaches the base side surface of the rotor 13 from the suction port 24 of the pump chamber 23 via the clearance between the rotor 13 and the side plate 20, and further passes through the outer periphery of the pump shaft 12 (shaft insertion space 81), The low-pressure lubricating oil supply system returns to the suction port 24 via the suction passage 25, and improves the lubrication performance in the sliding contact area between the rotor 13 and the side plate 20.

Therefore, according to the present embodiment, the following operations are provided. Since the high-pressure oil circulation path 70 guides the pressure fluid discharged from the pump chamber 23 to the base side surface of the rotor 13, this high-pressure oil is supplied to the clearance between the rotor 13 and the discharge-side side plate 18 to improve their lubrication performance. I can make it.
Therefore, the rotor 13 and the side plate 1 are arranged so that the fluid discharged from the pump chamber 23 effectively acts on the back of the vane 17.
The seizure between the rotor 13 and the side plate 18 can be prevented while the clearance between the rotor 8 and the rotor 8 is narrowed.

A sealing member 71 was provided at a fixed portion between the pump chamber 23 and the rotor 13. Therefore, in a state in which the high-pressure oil circulation path 70 is provided on the side surface of the base of the rotor 13, leakage of high-pressure oil can be prevented, and high-pressure oil can be effectively supplied to the clearance between the rotor 13 and the discharge side plate 18.

The low pressure oil circulation path 80 allows the pump chamber 23
The fluid on the suction side to the suction port 24 is circulated from the suction port 24 side to the suction passage 25 through the clearance between the rotor 13 and the suction side side plate 20, and the lubrication performance of the rotor 13 and the suction side side plate 20 can also be improved. . Therefore, seizure of the rotor 13 and the side plate 20 can be prevented while the clearance between the rotor 13 and the side plate 20 is further narrowed so that the discharge fluid of the pump chamber 23 effectively acts on the base of the vane 17.

Since the discharge side pressure chamber 28A and the high pressure oil circulation path 70 are formed on the first housing 11A side, the oil seal 15C through which the pump shaft 12 penetrates in the second housing 11B seals the low pressure oil in the low pressure side circulation path. It is enough to improve the sealing performance.

The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and the design may be changed without departing from the scope of the present invention. The present invention is also included in the present invention. For example, in the embodiment of the present invention, the above-described discharge flow control device 40 and vane pressurizing device 60 included in the variable displacement pump 10 can be variously modified in their configurations. In the embodiment of the present invention, the above-described side plate 18, adapter ring 19 and side plate 20 provided in the variable displacement pump 10 may be formed integrally with the pump housing 11. Further, the present invention can be applied to various devices other than the hydraulic power steering device.

[0043]

As described above, according to the present invention, in the variable displacement pump, the clearance between the rotor and the side plate on the pump housing side is reduced so that the fluid discharged from the pump chamber can effectively act on the back of the vane. In addition, the performance of lubrication between the rotor and the side plate can be improved to prevent seizure.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a variable displacement pump.

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

[Explanation of symbols]

 Reference Signs List 10 variable displacement pump 11 pump housing 11A first housing 11B second housing 12 pump shaft 13 rotor 15A first bearing 15B second bearing 15C oil seal 16 groove 16A base 17 vane 21 fulcrum pin 22 cam ring 23 pump chamber 24 suction port 25 Suction passage 27 Discharge port 28A Discharge side pressure chamber 40 Discharge flow control device 43 Pressurizing plunger 44A First fluid pressure chamber 44B Second fluid pressure chamber 46 Orifice 60 Vane pressurizing device 61, 62 Oil groove 63 Oil hole 70 High pressure oil circulation Road 71 Seal material 80 Low pressure oil circulation path

Claims (3)

[Claims] 1. A rotor fixed to a pump shaft inserted into a pump housing and driven to rotate, and capable of accommodating a large number of vanes in a groove so as to be movable in a radial direction. A cam ring forming a pump chamber between the cam ring and the outer periphery of the cam ring;
In addition, a biasing force for maximizing the volume of the pump chamber is applied to the cam ring, and first and second fluid pressure chambers are formed separately between the cam ring and the pump housing, and the pressure fluid discharged from the pump chamber is formed. The pressure before the orifice provided in the middle of the discharge passage is guided to the first fluid pressure chamber, the pressure after the orifice is guided to the second fluid pressure chamber, and the cam ring is biased by the differential pressure between the pressures acting on both fluid pressure chambers. A discharge flow control device that controls the discharge flow rate by changing the volume of the pump chamber by moving it against it, and guides the pressure fluid discharged from the pump chamber to the base of the groove containing the vane of the rotor. And a vane pressurizing device for pressurizing the vanes toward the cam ring, wherein a seal member is provided at a fixed portion between the pump shaft and the rotor, and a discharge fluid is discharged from the pump chamber. Variable displacement pump, characterized by comprising providing a high pressure oil circulation path to contact the base side of the rotor the pressure chamber via the outer periphery of the pump shaft. 2. The variable displacement pump according to claim 1, further comprising a low-pressure oil circulation path that connects a suction passage for guiding a suction-side fluid to the pump chamber to a base side surface of the rotor via an outer periphery of a pump shaft. 3. The pump housing comprises a first housing and a second housing connected to each other, wherein the pump shaft is inserted into the first housing through the second housing, and the pump shaft is provided on a side of the first housing. And a first bearing, a rotor, a cam ring, and a vane, a discharge-side pressure chamber is formed, and a second bearing for a pump shaft and an oil sheet are housed on a side of the second housing. 3. The variable displacement pump according to 2.