JP4275816B2 - Variable displacement pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable displacement pump used for a power steering device of an automobile or the like.
[0002]
[Prior art]
Conventionally, a variable displacement pump as described in Japanese Patent Application Laid-Open No. 8-200239 has been proposed in order to assist the steering force with a hydraulic power steering device of an automobile. This conventional variable displacement pump is directly rotated by an automobile engine. A rotor is provided in a cam ring that is movably fitted to an adapter ring that is fitted to a pump casing. A pump chamber is formed between the outer periphery.
[0003]
In this prior art, the cam ring is movable and displaceable in the adapter ring, and an urging force that maximizes the volume of the pump chamber is applied to the cam ring by the spring, and the first is interposed between the cam ring and the adapter ring. And the second fluid pressure chamber are divided, the cam ring is moved against the urging force by the pressure difference acting on both fluid pressure chambers, and the discharge flow rate can be controlled by changing the volume of the pump chamber. A discharge flow rate control device is provided. As a result, in this variable displacement pump, the discharge flow rate is increased so that a large steering assist force can be obtained when an automobile having a low rotational speed is stopped or traveling at low speed, and the steering assist force is decreased during high speed traveling at a high rotational speed. In this way, the discharge flow rate is controlled to be equal to or less than a certain amount, and the steering assist force required for the power steering device can be generated.
[0004]
[Problems to be solved by the invention]
However, in the prior art, the adapter ring is annular, and when the adapter ring is fitted to the pump casing, the adapter ring is thin and cannot be press-fitted. For this reason, when the adapter ring is fitted into the pump casing, a slight gap is required between the adapter ring and the presence of this gap causes unnecessary vibration of the adapter ring during operation of the pump. It can also cause sound.
[0005]
An object of the present invention is to reduce the occurrence of vibration and abnormal noise of the adapter ring during operation of the pump while improving the fitting and assembling property of the adapter ring to the pump casing in the variable displacement pump.
[0006]
[Means for Solving the Problems]
The present invention according to claim 1 is a pump casing configured by integrating a pump housing and a cover , and is rotationally driven fixedly to a pump shaft inserted into the pump housing and the cover of the pump casing. a rotor comprising a radially movable housing the vane in the groove, and the pressure plate and the adapter ring to be fitted in a stacked state in fitting hole of the pump housing of the pump casing, is fitted to the adapter ring, the pressure plate A cam ring that forms a pump chamber between the rotor and the outer periphery of the rotor, a suction port that is provided on the cover and opens upstream of the pump chamber in the rotor rotation direction, and a pressure plate that is provided on the pressure plate. a discharge port which opens in the rotor rotational direction downstream side, the displacement allowed the cam ring in the adapter in the ring And then, and with the volume of the pump chamber is applied to the cam ring the biasing force such that the maximum, the first and second fluid pressure chamber divided formed between the cam ring and the adapter ring, the outer peripheral surface of the adapter ring Displacement flow rate can be controlled by changing the volume of the pump chamber by moving the cam ring against the urging force by the differential pressure of the pressure acting on both fluid pressure chambers through the communication passage drilled in the inner peripheral surface In the variable displacement pump having the discharge flow rate control device, the adapter ring is inserted into the fitting hole of the pump housing through an O-ring provided on the cover side of the communication path provided in the adapter ring. It is designed to be fitted.
[0007]
[Action]
According to invention of Claim 1, there exists an effect | action of (1)-(3).
(1) The adapter ring can be easily fitted into the fitting hole of the pump casing while the O-ring is elastically deformed during fitting assembly to the pump casing, so that the fitting and assembling performance can be improved.
[0008]
(2) After the adapter ring is fitted and assembled to the pump casing, an O-ring is interposed between the pump casing and the pump casing to reduce vibrations and noise from the adapter ring during pump operation. it can.
[0009]
(3) The adapter when the pump is in operation with a simple configuration using only an O-ring without the need to increase the accuracy of processing the fitting hole of the pump casing and the processing accuracy of the outer peripheral surface of the adapter ring. Ring vibration and noise can be reduced.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
1 is a cross-sectional view showing a variable displacement pump, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, and FIG. 3 is a schematic view showing an adapter ring.
[0011]
The variable displacement pump 10 is a vane pump serving as a hydraulic pressure generation source of a hydraulic power steering device of an automobile. As shown in FIGS. 1 and 2, the variable displacement pump 10 is rotationally driven by being fixed to a pump shaft 12 inserted into a pump casing 11 by serrations. The rotor 13 is provided. The pump casing 11 is configured by integrating a pump housing 11A and a cover 11B with bolts 14, and supports the pump shaft 12 via bearings 15A to 15C. The pump shaft 12 can be directly rotated by an automobile engine.
[0012]
The rotor 13 accommodates vanes 17 in grooves 16 provided at a plurality of positions in the circumferential direction, and the vanes 17 can be moved in the radial direction along the grooves 16.
[0013]
In the fitting hole 20 of the pump housing 11A of the pump casing 11, a pressure plate 18 and an adapter ring 19 are fitted in a laminated state, and these are positioned on the side by the cover 11B while being positioned in a circumferential direction by a fulcrum pin 21 described later. It is fixed and held from one side. One end of the fulcrum pin 21 is attached and fixed to the cover 11B.
[0014]
A cam ring 22 is fitted to the adapter ring 19 fixed to the pump casing 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 pressure plate 18 and the cover 11 </ b> B and the outer periphery of the rotor 13. A suction port 24 provided in the cover 11B is opened on the upstream side in the rotor rotation direction of the pump chamber 23. The suction port 24 is connected to the pump 10 via suction passages 25A and 25B provided in the housings 11A and 11B. A suction port 26 is communicated. On the other hand, a discharge port 27 provided in the pressure plate 18 is opened downstream of the pump chamber 23 in the rotor rotation direction. The discharge port 27 has a high pressure chamber 28A and a discharge passage 28B (not shown) provided in the housing 11A. A discharge port 29 (not shown) of the pump 10 is communicated with each other.
[0015]
Thus, in the variable displacement pump 10, when the rotor 13 is rotationally driven by the pump shaft 12 and the vane 17 of the rotor 13 is pressed against the cam ring 22 by centrifugal force and rotates, the rotor rotation direction of the pump chamber 23 On the downstream side, the volume enclosed by the adjacent vanes 17 and the cam ring 22 is increased with rotation and the working fluid is sucked from the suction port 24, and between the adjacent vanes 17 and the cam ring 22 on the upstream side in the rotor rotation direction of the pump chamber 23. The working volume is discharged from the discharge port 27 by reducing the volume enclosed by the rotation.
[0016]
However, the variable displacement pump 10 has a discharge flow rate control device 40 as shown below (A) and a vane pressurizing device 60 as shown below (B).
(A) Discharge flow rate control device 40
The discharge flow rate control device 40 places the aforementioned fulcrum pin 21 on the lowest vertical part of the aforementioned adapter ring 19 fixed to the pump casing 11, and supports the lowest vertical part of the cam ring 22 on this fulcrum pin 21. The cam ring 22 can be oscillated and displaced within the adapter ring 19.
[0017]
The discharge flow rate control device 40 presses the spring 42 accommodated in the spring chamber 41 provided in the pump housing 11 </ b> A constituting the pump casing 11 through the spring hole 19 </ b> A provided in the adapter ring 19 and presses the outer periphery of the cam ring 22. Thus, an urging force that maximizes the volume of the pump chamber 23 can be applied to the cam ring 22. The spring 42 is backed up by a cap 41 </ b> A that is screwed into the opening of the spring chamber 41. The adapter ring 19 has a cam ring movement restricting stopper 19B formed in a convex shape on a part of an inner peripheral portion forming a second fluid pressure chamber 44B, which will be described later, and a cam ring 22 that minimizes the volume of the pump chamber 23 as will be described later. The movement limit can be regulated.
[0018]
Further, the discharge flow rate control device 40 divides and forms first and second fluid pressure chambers 44 </ b> A and 44 </ b> B between the cam ring 22 and the adapter ring 19. That is, the first fluid pressure chamber 44 </ b> A and the second fluid pressure chamber 44 </ b> B are divided between the cam ring 22 and the adapter ring 19 by the fulcrum pin 21 and the seal material 45 provided at the axially symmetric position.
[0019]
Here, in the discharge path of the pump 10 described above, the pressure fluid discharged from the pump chamber 23 and sent from the discharge port 27 of the pressure plate 18 to the high pressure chamber 28A of the pump housing 11A was drilled in the pressure plate 18. From the orifice 46, the second fluid pressure chamber 44B, the spring chamber 41 passing through the adapter ring 19, and a discharge communication hole (not shown) formed in the fitting hole 20 of the pump housing 11A. Thus, the pressure is fed to the discharge passage 28B.
[0020]
The discharge flow rate control device 40 increases or decreases the opening area of the orifice 46 that opens to the second fluid pressure chamber 44B in the discharge path of the pump 10 described above, thereby forming a variable metering orifice. That is, the opening of the orifice 46 is adjusted at the side wall with the displacement of the cam ring 22. The discharge flow rate control device 40 (1) supplies the high fluid pressure before passing through the orifice 46 via the first fluid pressure supply passage 47A, the switching valve 48, the pump housing 11A, and the communication passage 49 formed in the adapter ring 19. 2) The reduced pressure after passing through the orifice 46 is led to the second fluid pressure chamber 44B as described above, and the cam ring 22 is moved by the differential pressure of the pressure acting on both the fluid pressure chambers 44A and 44B. The pump 10 is moved against the urging force of the spring 42 described above, and the volume of the pump chamber 23 is changed to control the discharge flow rate of the pump 10.
[0021]
The switching valve 48 accommodates a spring 52 and a switching plunger 53 in a valve storage hole 51 formed in the front casing 11A, and a plunger 53 biased by the spring 52 is supported by a cap 54 screwed to the casing 11A. ing. The switching plunger 53 includes a switching valve body 55A and a valve body 55B. The first fluid pressure supply passage 47A communicates with the pressurizing chamber 56A of the switching valve body 55A, and the other spring 52 of the valve body 55B is stored. The second fluid pressure chamber 44B is communicated with the back pressure chamber 56B via the pump housing 11A and the communication passage 57 formed in the adapter ring 19. In addition, the suction passage 25A described above is formed through the intermediate chamber 56C between the switching valve body 55A and the valve body 55B, and the suction side fluid is supplied. The switching valve body 55A is capable of opening and closing the above-described communication passage 49 formed in the pump housing 11A and the adapter ring 19. That is, in the low rotation range where the discharge pressure of the pump 10 is low, the switching plunger 53 is set to the original position shown in FIG. 2 by the urging force of the spring 52, and the communication passage 49 with the first fluid pressure chamber 44A by the switching valve body 55A. Is closed and the switching plunger 53 is moved by the high pressure fluid applied to the pressurizing chamber 56A in the middle and high rotation range of the pump 10 to open the communication passage 49, and this high pressure fluid can be guided to the first fluid pressure chamber 44A. .
[0022]
Therefore, the discharge flow rate characteristics of the pump 10 provided with the discharge flow rate control device 40 are as follows.
(1) In a low-speed traveling region of an automobile in which the rotation speed of the pump 10 is low, the pressure of the fluid discharged from the pump chamber 23 and reaching the pressurizing chamber 56A of the switching valve 48 is still low, and the switching valve 48 is located at the original position. The cam ring 22 maintains the original state biased by the spring 42. For this reason, the discharge flow rate of the pump 10 increases in proportion to the rotational speed.
[0023]
(2) When the pressure of the fluid discharged from the pump chamber 23 and reaching the pressurizing chamber 56A of the switching valve 48 increases due to the increase in the rotation speed of the pump 10, the switching valve 48 switches against the urging force of the spring 52. The plunger 53 is moved to open the communication passage 49, and this high-pressure fluid is guided to the first fluid pressure chamber 44A. As a result, the cam ring 22 moves due to the differential pressure between the pressures acting on the first fluid pressure chamber 44A and the second fluid pressure chamber 44B, and the volume of the pump chamber 23 is gradually reduced. Accordingly, the discharge flow rate of the pump 10 can maintain a constant large flow rate by offsetting the increase in flow rate due to the increase in rotation rate and the decrease in flow rate due to the volume reduction of the pump chamber 23 with respect to the increase in rotation rate. it can.
[0024]
(3) When the rotation speed of the pump 10 continues and further increases and the cam ring 22 further moves and the cam ring 22 pushes the spring 42 beyond a certain amount, the side wall of the cam ring 22 is removed from the pump chamber 23. The opening area of the orifice 46 in the middle of the discharge path is started to be reduced. Accordingly, the discharge flow rate of the pump 10 decreases in proportion to the amount of restriction of the orifice 46.
[0025]
(4) When the rotational speed of the pump 10 reaches a high speed operation range of the automobile exceeding a certain value, the cam ring 22 reaches a moving limit where it abuts against the stopper 19B of the adapter ring 19, and the amount of restriction of the orifice 46 by the side wall of the cam ring 22 The discharge flow rate of the pump 10 is maintained at a constant small flow rate.
[0026]
(B) Vane pressurizing device 60
The vane pressurizing device 60 includes a ring-shaped oil groove 61 on the sliding surface of the pressure plate 18 and the groove 16 of the side plate 20 corresponding to both sides of the base portion 16A of the groove 16 accommodating the vane 17 of the rotor 13. 62 is provided. The high pressure chamber 28 </ b> A of the pump chamber 23 provided in the pump housing 11 </ b> A communicates with the above-described oil groove 61 through an oil hole 63 provided in the pressure plate 18. As a result, the pressure fluid discharged from the pump chamber 23 to the high pressure chamber 28 </ b> A passes through the oil grooves 61 and 62 of the pressure plate 18 and the side plate 20, and the grooves 16 for all the vanes 17 in the circumferential direction of the rotor 13 are formed. The vane 17 is guided to the base and can be pressurized toward the cam ring 22.
[0027]
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 pressurizing device 60 causes the contact pressure between the vane 17 and the cam ring 22 to be increased. The backflow of the pressure fluid can be prevented.
[0028]
However, in the pump 10, as shown in FIGS. 1 and 2, the adapter ring 19 is fitted into the fitting hole 20 of the pump housing 11 </ b> A via the O-ring 70. The O-ring 70 is attached to a groove 71 (FIG. 3) provided on the outer peripheral surface of the adapter ring 19. In the present embodiment, the O-ring 70 is provided on the outer peripheral surface of the adapter ring 19 on the cover 11B side of the communication passages 49 and 57 provided in the adapter ring 19, but the O-ring 70 is provided on the outer periphery of the adapter ring 19. In terms of surface, the communication passages 49 and 57 may be provided on the side opposite to the cover 11B, or may be provided on both sides of the communication passages 49 and 57.
[0029]
In the cover 11B of the pump 10, a lubricating oil supply passage 121 is drilled from the suction passage 25B around the bearing 15C of the pump shaft 12, and in the pump housing 11A, from around the bearing 15B of the pump shaft 12. A lubricating oil return path 122 that returns to the suction path 25A is formed.
[0030]
Therefore, according to the present embodiment, there are the following operations.
(1) The adapter ring 19 is easily fitted into the fitting hole 20 of the pump housing 11A while being elastically deformed in the O-ring 70 during fitting assembly to the pump housing 11A. it can.
[0031]
(2) After the adapter ring 19 is fitted and assembled into the pump housing 11A, an O-ring 70 is interposed between the adapter ring 19 and the pump housing 11A, and the vibration of the adapter ring 19 during operation of the pump 10 Generation of abnormal noise can be reduced.
[0032]
(3) The pump 10 has a simple configuration using only the O-ring 70 without the need to improve the processing accuracy of the fitting hole 20 of the pump housing 11A and the processing accuracy of the outer peripheral surface of the adapter ring 19. It is possible to reduce the vibration of the adapter ring 19 and the generation of abnormal noise during the operation of
[0033]
Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. However, it is included in the present invention. For example, the O-ring 70 may be mounted in a groove provided on the inner peripheral surface of the fitting hole 20 of the pump casing 11 (pump housing 11A).
[0034]
【The invention's effect】
As described above, according to the present invention, in the variable displacement pump, the adapter ring can be easily assembled and assembled to the pump casing, and the vibration of the adapter ring and the generation of abnormal noise during operation of the pump can be reduced. Can do.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a variable displacement pump.
FIG. 2 is a cross-sectional view taken along line II-II in FIG.
FIG. 3 is a schematic view showing an adapter ring.
[Explanation of symbols]
10 Variable displacement pump 11 Pump casing
11A Pump housing
11B Cover 12 Pump shaft 13 Rotor 16 Groove 17 Vane
18 Pressure plate 19 Adapter ring 20 Fitting hole 22 Cam ring 23 Pump chamber
24 Suction port
27 Discharge port 40 Discharge flow rate control device 41 Spring chamber 42 Spring 44A First fluid pressure chamber 44B Second fluid pressure chamber
49, 57 Communication path 70 O-ring

Claims (1)

A pump casing configured by integrating a pump housing and a cover;
A rotor that is fixed to a pump shaft inserted into a pump housing and a cover of a pump casing and is rotationally driven, and a large number of vanes are accommodated in grooves and movable in a radial direction,
A pressure plate and an adapter ring that are fitted into the fitting hole of the pump housing of the pump casing in a stacked state ;
A cam ring that is fitted to the adapter ring and forms a pump chamber between the pressure plate and the cover and the outer periphery of the rotor;
A suction port provided in the cover and opening upstream of the rotor rotation direction of the pump chamber;
A discharge port provided in the pressure plate and opening downstream of the pump chamber in the rotor rotation direction;
The cam ring is movable and displaceable within the adapter ring, and an urging force that maximizes the volume of the pump chamber is applied to the cam ring, and the first and second fluid pressure chambers are divided between the cam ring and the adapter ring. The cam ring is moved against the urging force by the pressure difference acting on both fluid pressure chambers through the communication passage formed from the outer peripheral surface of the adapter ring to the inner peripheral surface, and the pump chamber In a variable displacement pump having a discharge flow rate control device capable of controlling the discharge flow rate by changing the volume,
The variable capacity pump, wherein the adapter ring is fitted into a fitting hole of a pump housing via an O-ring provided on the cover side of the communication path provided in the adapter ring .

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