JP2010229863A - Variable displacement pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a machining property, and to avoid the deterioration of the strength of a pump housing when a discharge connecting hole formed at the pump housing and making a spring chamber communicate with a discharging passage is formed, in a variable displacement pump. <P>SOLUTION: In the variable displacement pump 10, the discharge connecting hole 100 formed at the pump housing 11A is composed of a first discharge connecting hole 100A formed by casting a part of an inner periphery of a spring chamber 41 over the full length in an axial direction of the spring chamber 41 with the spring chamber 41, and a second discharge connecting hole 100B formed from a discharging passage to the first discharge connecting hole 100A. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a variable displacement pump used for a power steering device of an automobile.

  Conventionally, a variable displacement pump described in Patent Document 1 has been proposed in order to assist a steering force with a hydraulic power steering device of an automobile. This conventional variable displacement pump is directly driven to rotate by an automobile engine, is fixed to a pump shaft inserted into a pump housing and is driven to rotate, and a large number of vanes are accommodated in grooves and have a radius. Having a rotor that is movable in the direction, a pressure plate and an adapter ring are fitted to the pump housing in a stacked state, a cover is attached to the mating surface of the pump housing, a cam ring is fitted to the adapter ring, A pump chamber is formed between the inner periphery of the cam ring and the outer periphery of the rotor between the pressure plate and the cover, and a discharge port is provided on the pressure plate, and a suction port is provided on the cover side.

  In this prior art, the cam ring can be moved and displaced in the adapter ring, and a spring that acts on the cam ring to apply a biasing force that maximizes the volume of the pump chamber passes from the pump housing through the adapter ring to the cam ring. The first and second fluid pressure chambers are divided between the cam ring and the adapter ring, and the pressure fluid discharged from the pump chamber is discharged from the discharge port of the pressure plate to the back surface of the pressure plate. The high pressure chamber on the side, the orifice formed in the pressure plate, the second fluid pressure chamber and the spring chamber are led to the discharge passage of the pump housing, and the pressure fluid discharged from the pump chamber before the orifice The pressure after the orifice is guided to the first fluid pressure chamber and the pressure after the orifice to the second fluid pressure chamber. The Muringu is moved against the biasing force, thereby enabling control of the discharge flow rate by varying the volume of the pump chamber. 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 the automobile having a low rotational speed is stopped or traveling at a low speed, and the steering assist force is decreased during a 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, so that the steering assist force required for the power steering device can be generated.

JP2000-265976

  However, in the variable displacement pump described in Patent Document 1, the discharge communication hole provided in the pump housing and communicating the spring chamber with the discharge passage is the inner surface of the fitting hole that allows the adapter ring of the pump housing to be fitted. Thus, the first discharge communication hole formed by countersinking the inner surface connected to the spring chamber and the second discharge communication hole formed from the discharge passage to the first discharge communication hole are formed.

  The first discharge communication hole is countersunk on the inner surface of the adapter ring fitting hole of the pump housing, so that the workability is poor and the strength of the pump housing may be reduced.

  An object of the present invention is to improve workability and avoid a reduction in strength of a pump housing when forming a discharge communication hole provided in a pump housing and communicating a spring chamber with a discharge passage in a variable displacement pump. It is in.

  The invention of claim 1 has a rotor which is fixed to a pump shaft inserted into the pump housing and is rotationally driven, and which has a large number of vanes accommodated in grooves so as to be movable in the radial direction. The plate and adapter ring are fitted in a stacked state, a cover is attached to the mating surface of the pump housing, a cam ring is fitted on the adapter ring, and the inner periphery of the cam ring and the rotor are placed between the pressure plate and the cover. A pump chamber is formed between the outer periphery and the pressure plate. A discharge port is provided on the pressure plate, and a suction port is provided on the cover side. The cam ring can be moved and displaced within the adapter ring, and the volume of the pump chamber is maximized. A spring that applies a biasing force to the cam ring is installed in the spring chamber that passes through the adapter ring from the pump housing and faces the cam ring. The first and second fluid pressure chambers are formed separately between the cam ring and the adapter ring, and the pressure fluid discharged from the pump chamber is supplied from the discharge port of the pressure plate to the high pressure chamber on the back side of the pressure plate. The pressure plate discharges the pressure fluid from the pump chamber through the orifice formed in the pressure plate, the second fluid pressure chamber and the spring chamber to the discharge passage of the pump housing. The pressure after the orifice is led to the fluid pressure chamber to the second fluid pressure chamber, the cam ring is moved against the biasing force by the pressure difference acting on both fluid pressure chambers, and the volume of the pump chamber is changed. The discharge flow rate becomes controllable, and a spring chamber provided in the pump housing is formed through the inside and outside of the pump housing, and the outer end of the spring chamber is closed by a plug, In a variable displacement pump in which a spring chamber and a discharge passage are arranged to cross each other and communicate with each other through a discharge communication hole provided in the pump housing, the discharge communication hole provided in the pump housing has a part of the inner periphery of the spring chamber. A first discharge communication hole cast out together with the spring chamber over the entire length along the axial direction of the spring chamber, and a second discharge communication hole drilled from the discharge passage to the first discharge communication hole. It is.

(Claim 1)
A first discharge communication hole of the discharge communication hole provided in the pump housing and communicating the spring chamber with the discharge passage is part of the inner circumference of the spring chamber along with the spring chamber over the entire length along the axial direction of the spring chamber. It consists of a cast. Therefore, the first discharge communication hole can be formed simultaneously with the spring chamber by casting at the time of casting the pump housing, thereby improving workability and avoiding a decrease in strength of the pump housing.

FIG. 1 is a cross-sectional view showing a variable displacement pump. FIG. 2 is a sectional view taken along line II-II in FIG. FIG. 3 is a sectional view taken along line III-III in FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.

  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 to 3, 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.

  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.

  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 circumferentially 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.

  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 opens on the downstream side of the pump chamber 23 in the rotor rotation direction. The discharge port 27 is pumped through a high pressure chamber 28A and a discharge passage 28B provided in the housing 11A. Ten discharge ports 29 communicate with each other. The details of the discharge path of the pump 10 (the path from the high pressure chamber 28A to the discharge path 28B) will be described later.

  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.

  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. Then, the discharge flow rate control device 40 penetrates and forms the spring chamber 41 provided in the pump housing 11A over the inside and outside of the pump housing 11A, and passes the adapter ring 19 from the pump housing 11A to face the cam ring 22. The outer end of the spring chamber 41 is closed by a plug 41A screwed into the outer opening of the spring chamber 41 provided in the pump housing 11A, and the volume of the pump chamber 23 is increased by a spring 42 backed up by the plug 41A. The cam ring 22 can be applied with an urging force that maximizes.

  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 axial target position.

  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. Pressure is fed from the orifice 46 to the discharge passage 28B through the second fluid pressure chamber 44B, the spring chamber 41 penetrating the adapter ring 19, and the discharge communication hole 100 formed in the pump housing 11A. It has become. The specific configuration of the discharge communication hole 100 will be described later.

  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 (a) transmits 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. (B) The reduced pressure after passing through the orifice 46 is guided to the second fluid pressure chamber 44B as described above, and the cam ring 22 is moved by the differential pressure between the pressures 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.

  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. 1 by the biasing force of the spring 52, and the communication passage 49 with the first fluid pressure chamber 44A is switched 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. .

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.

  (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.

  (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.

  (4) When the rotational speed of the pump 10 reaches a high-speed driving range of the automobile, the cam ring 22 reaches the movement limit, the amount of restriction of the orifice 46 by the side wall of the cam ring 22 becomes maximum, and the discharge flow rate of the pump 10 is Maintain a constant small flow rate.

(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 front casing 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.

  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.

  However, in the pump 10, the discharge communication hole 100 provided in the pump housing 11A and communicating the spring chamber 41 with the discharge passage 28B is configured as follows. The central axis of the spring chamber 41 and the central axis of the discharge passage 28B are arranged so as to intersect each other.

  As shown in FIGS. 2 to 4, the discharge communication hole 100 has a part of the inner circumference forming a circular cross section of the spring chamber 41 over the entire length parallel to the axial direction of the spring chamber 41. A first discharge communication hole 100A having a semicircular cross section that is cast together with the second discharge communication hole 100B drilled from the discharge passage 28B to the first discharge communication hole 100A by a drill or the like.

  In the pump 10, an O-ring 102 </ b> A is loaded in the outer peripheral groove of the fitting surface 102 of the cover 11 </ b> B that is attached to the fitting hole 20 of the pump housing 11 </ b> A at the joint surface 101 of the pump housing 11 </ b> A and the cover 11 </ b> B. Then, the fitting hole 20 is sealed. Further, even at the connecting portion between the suction passage 25A of the pump housing 11A and the suction passage 25B of the cover 11B, an O-ring 103A is loaded in the circumferential groove of the abutting surface 103 of the cover 11B to seal the suction passages 25A and 25B. .

  In the pump housing 11 of the pump 10, a relief passage 110 and a relief valve 111 are provided between the discharge passage 28B and the suction passage 25A so that the discharge pressure of the pump 10 can be relieved. Further, in the cover 11B of the pump 10, a lubricating oil supply passage 121 is formed 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.

Therefore, according to the present embodiment, the following operational effects can be obtained.
The first discharge communication hole 100A of the discharge communication hole 100 that is provided in the pump housing 11A and communicates the spring chamber 41 with the discharge passage 28B is part of the inner circumference of the spring chamber 41 along the axial direction of the spring chamber 41. It consists of what was cast together with this spring chamber 41. Therefore, the first discharge communication hole 100A can be formed simultaneously with the spring chamber 41 by casting at the time of casting the pump housing 11A, so that the workability can be improved and the strength reduction of the pump housing 11A can be avoided.

  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 even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

  According to the first aspect of the present invention, in the variable displacement pump, the discharge communication hole provided in the pump housing is formed by casting a part of the inner periphery of the spring chamber together with the spring chamber over the entire length along the axial direction of the spring chamber. It consists of a discharge communication hole and a second discharge communication hole drilled from the discharge passage to the first discharge communication hole. Therefore, in the variable displacement pump, when forming the discharge communication hole provided in the pump housing and connecting the spring chamber to the discharge passage, the workability can be improved and the strength of the pump housing can be avoided.

DESCRIPTION OF SYMBOLS 10 Variable displacement pump 11A Pump housing 11B Cover 12 Pump shaft 13 Rotor 16 Groove 16A Base 17 Vane 18 Pressure plate 19 Adapter ring 20 Fitting hole 21 Support point pin 22 Cam ring 23 Pump chamber 24 Suction port 27 Discharge port 28A High pressure chamber 28B Discharge passage 40 Discharge flow rate control device 41 Spring chamber 41A Plug 42 Spring 43 Pressurizing plunger 44A First fluid pressure chamber 44B Second fluid pressure chamber 46 Orifice 100 Discharge communication hole 100A First discharge communication hole 100B Second discharge communication hole

Claims (1)

A rotor fixed to a pump shaft inserted into a pump housing and driven to rotate, and having a rotor capable of moving in a radial direction by accommodating a number of vanes in a groove,
The pressure plate and adapter ring are fitted to the pump housing in a stacked state, the cover is attached to the mating surface of the pump housing, the cam ring is fitted to the adapter ring, and the inner circumference of the cam ring is placed between the pressure plate and the cover. A pump chamber is formed between the outer periphery of the rotor and the rotor, a discharge port is provided on the pressure plate, and a suction port is provided on the cover side.
A spring that allows the cam ring to move and displace within the adapter ring and acts on the cam ring with a biasing force that maximizes the volume of the pump chamber is installed in the spring chamber facing the cam ring from the pump housing through the adapter ring, Forming the first and second fluid pressure chambers separately between the cam ring and the adapter ring;
The pressure fluid discharged from the pump chamber is pumped from the discharge port of the pressure plate through the high pressure chamber on the back side of the pressure plate, the orifice drilled in the pressure plate, the second fluid pressure chamber and the spring chamber. Lead to the discharge passage of the housing,
The pressure fluid discharged from the pump chamber leads the pressure before the orifice to the first fluid pressure chamber, the pressure after the orifice to the second fluid pressure chamber, and the cam ring is formed by the differential pressure of the pressure acting on both fluid pressure chambers. It can move against the urging force, change the volume of the pump chamber and control the discharge flow rate,
A spring chamber provided in the pump housing is formed through the inside and outside of the pump housing, the outer end of the spring chamber is closed by a plug, and the spring chamber and the discharge passage are arranged so as to cross each other. In variable displacement pumps connected by discharge communication holes,
A discharge communication hole provided in the pump housing includes a first discharge communication hole in which a part of the inner circumference of the spring chamber is cast together with the spring chamber over the entire length along the axial direction of the spring chamber, and a first from the discharge passage. A variable displacement pump characterized by comprising a second discharge communication hole drilled to the discharge communication hole.

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