JP3942806B2 - Variable displacement pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable displacement pump used in a pressure fluid utilizing device such as a power steering device that reduces the steering force of an automobile.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a displacement vane pump that is directly driven to rotate by an automobile engine has been used for this type of power steering device pump. Such a displacement pump increases or decreases the discharge flow rate according to the engine speed, so that the steering assist force is increased when the automobile is stopped or traveling at low speed, and the steering assist force is decreased when traveling at high speed. It must have characteristics that contradict the steering assist force required for the device. Therefore, it is necessary to use a large-capacity displacement pump that can secure a discharge flow rate at which a necessary steering assist force can be obtained even during low-speed traveling at a low rotational speed. In addition, a flow rate control valve that controls the discharge flow rate to a certain amount or less is essential during high-speed traveling at a high rotational speed. For this reason, the number of component parts becomes relatively large, the structure and the passage configuration become complicated, and it is inevitable that the whole is increased in size and cost.
[0003]
In order to solve such a problem, a variable displacement vane pump capable of decreasing the discharge flow rate per rotation (cc / rev) in proportion to the increase in the rotational speed is disclosed in JP-A-6-200883, Japanese Laid-Open Patent Publication No. 7-243385, Japanese Laid-Open Patent Publication No. 8-200239, and the like. According to these variable displacement pumps, the flow rate control valve attached to the displacement pump is not necessary, and the driving horsepower can be reduced, so that the energy efficiency is excellent.
[0004]
For example, in the pump disclosed in Japanese Patent Application Laid-Open No. 8-200279, as shown in FIG. 7, the rotor 3 is relatively eccentric in a cam ring 2 that is swingably supported in an elliptical space inside the pump body 1. By providing in a state, a substantially crescent-shaped pump chamber 4 is formed between the rotor 3 and the cam ring 2. Further, first and second fluid pressure chambers 5 and 6 are formed on both sides of the cam ring 2 in the swinging direction. The second fluid pressure chamber 6 is provided with a compression coil spring 2b that urges the pump chamber 4 in a direction that maximizes the pump capacity. A control valve 10 is provided on the variable metering throttle 12 provided in the middle of the discharge-side passage 11 for the pressure fluid discharged from the pump chamber 4 and is operated by a fluid pressure difference on the downstream side. The cam ring 2 is swung by controlling the fluid pressure in the first and second fluid pressure chambers 5 and 6.
[0005]
By adjusting the opening area of the hole 12a at the side edge 12b of the cam ring 2 by swinging the cam ring 2, the hole 12a opened on the side wall surface of the body 1 facing the second fluid pressure chamber 6 is obtained. A variable metering diaphragm 12 is formed. That is, among the first and second fluid pressure chambers 5 and 6 for swinging the cam ring 2, the structure is such that the fluid pressure downstream of the variable metering restrictor 12 is directly introduced into the second fluid pressure chamber 6. It has become. Then, the pressure fluid discharged from the pump chamber 4 is guided to the hole 12a forming the variable metering throttle 12, and the pressure fluid flowing into the second fluid pressure chamber 6 from the hole 12a is supplied to the second fluid pressure chamber 6. Is sent to the pump discharge side passage 13 through the fluid pressure chamber 6 and discharged from a discharge port (not shown).
[0006]
In the variable displacement pump described above, the passage 5a having a damper throttle into the first fluid pressure chamber 5 into which the control valve 10 introduces the fluid pressure upstream of the variable metering throttle 12 when the pump reaches a high rotation range. The structure which introduces fluid pressure via is adopted. In such a structure, when the cam ring 2 swings toward the first fluid pressure chamber 5 side, a required braking force is applied to the cam ring 2 by a damper function by a damper throttle of the passage 5a. be able to.
[0007]
[Problems to be solved by the invention]
However, as described above, the second fluid pressure chamber 6 is only provided with the compression coil spring 2b, and has a damper function for applying a braking force to the cam ring 2 like the first fluid pressure chamber 5 side. There is no means to have. This is because the hole 12a of the variable metering throttle 12 is opened in the second fluid pressure chamber 6, and this opening is also used as a part of the discharge side passages 7 and 13 of the pump. This is because the fluid pressure on the pump discharge side flows in 6. In the figure, reference numeral 6 a denotes a passage for guiding the fluid pressure downstream of the variable metering throttle 12 to the other chamber of the control valve 10.
[0008]
Therefore, when the cam ring 2 swings to the second fluid pressure chamber 6 side, although the elastic force due to the spring 2b being bent acts, the braking by the damper function cannot be applied. For this reason, the cam ring 2 can smoothly swing toward the first and second fluid pressure chambers 5 and 6 (particularly the swing operation from the first fluid pressure chamber 5 side to the second fluid pressure chamber 6 side). Not made. In this case, it is inevitable that the cam ring 2 vibrates or pulsates in the fluid pressure on the pump discharge side. This pulsation state is indicated by a broken line in FIG.
[0009]
More specifically, when the fluid pressure on the pump discharge side flows into the second fluid pressure chamber 6 as a jet from the hole 12a that opens to the second fluid pressure chamber 6, it is attempted to open and close this at the outer edge 12b of the cam ring 2. The cam ring 2 is likely to vibrate, and the jet flow from the hole 12a is blocked or allowed to pass by the outer edge 12b of the cam ring 2, thereby increasing the pulsation on the pump discharge side. When such vibrations and pulsations occur, the power steering apparatus has a problem that the steering force fluctuates and noise such as fluid noise increases.
[0010]
The present invention has been made in view of such circumstances, and an object of the present invention is to obtain a variable displacement pump with reduced cam ring vibration and pulsation on the pump discharge side.
[0011]
[Means for Solving the Problems]
In order to meet such a demand, the variable displacement pump according to the present invention supports a cam ring that forms a pump chamber so as to be swingable within the internal space of the pump body, and is arranged on one side in the swing direction of the cam ring. A first fluid pressure chamber, a second fluid pressure chamber on the other side, and a biasing means for biasing the cam ring in a direction in which the pump capacity of the pump chamber is maximized. A control valve that operates according to a downstream fluid pressure difference is provided above a variable metering throttle provided in the middle of the discharge-side passage of the pressure fluid discharged from the fluid, and at least the fluid pressure in the first fluid pressure chamber is provided by the control valve. In the structure in which the cam ring is swung by controlling the cam ring, the variable metering diaphragm is recessed in a side surface portion on one side in the axial direction of the cam ring. Or in the axial direction so as to open in the side surface on one side of the cam ring A communication groove communicating with the discharge side opening of the pump chamber formed in the side wall portion of the pump body that is formed through and facing the side surface portion, and is opened at a position facing the part of the communication groove on the side wall portion of the pump body. A hole portion whose opening area can be adjusted by the groove side edge of the communication groove as the cam ring swings is provided at a position partitioned from the second fluid pressure chamber. .
[0012]
According to the present invention Since the variable metering restrictor is provided in the section where the fluid pressure in the second fluid pressure chamber is not affected, the cam ring has a damper function by the fluid pressure in the first and second fluid pressure chambers. It can be held and swung.
[0014]
Moreover, according to the present invention, The hole on the side wall portion side of the pump body facing the communication groove recessed in the side surface portion of the cam ring is closed or opened at the groove side edge of the communication groove as the cam ring swings. The diaphragm amount of the variable metering diaphragm can be adjusted.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
1 to 4 are views showing an embodiment of a variable displacement pump according to the present invention. In this embodiment, the vane pump according to the present invention is a vane-type oil pump that serves as a hydraulic pressure generation source of the power steering apparatus, and the discharge flow rate becomes higher than the maximum discharge flow rate as the number of rotations of the pump increases. A description will be given of a pump having a so-called drooping characteristic that maintains a low predetermined flow rate.
[0016]
1, 2, and 3, a vane type variable displacement pump, generally indicated by reference numeral 20, includes a front body 21 and a rear body 22 that constitute a pump body. The front body 21 has a substantially cup shape as a whole, and a storage space 24 for storing and arranging a pump component 23 as a pump cartridge is formed inside the front body 21 and the opening end of the storage space 24 is closed. The rear body 22 is combined and assembled together.
[0017]
The front body 21 has bearings 26a and 26b (26a on the front body 21 side and 26b on the rear body 22 side) in a state where a drive shaft 26 for rotating and driving the rotor 25 constituting the pump component 23 from the outside passes through. Is disposed rotatably. 26c is an oil seal. The rotor 25 rotates counterclockwise as indicated by an arrow in FIG.
[0018]
Reference numeral 27 denotes a cam ring. The cam ring 27 has an inner cam surface 27 a that is fitted on the outer periphery of the rotor 25 having a vane 25 a, and a pump chamber 28 is provided between the inner cam surface 27 a and the rotor 25. Is forming. The cam ring 27 is positioned in an eccentric state with respect to the rotor 25, and a substantially crescent-shaped space formed between the cam ring 27 and the rotor 25 serves as a pump chamber 28. In addition, the cam ring 27 is disposed so as to be swingable in an adapter ring 29 that is fitted in the inner wall portion of the storage space 24 so that the volume (pump capacity) of the pump chamber 28 can be varied as will be described later. Has been. Reference numeral 27b denotes a compression coil spring that urges the cam ring 27 in a direction in which the pump capacity of the pump chamber 28 is maximized.
[0019]
2 and 3, reference numeral 30 denotes a pressure plate. The pressure plate 30 is disposed on the front body 21 side of the pump cartridge (pump component 23) constituted by the rotor 25, the cam ring 27 and the adapter ring 29 described above. They are stacked in pressure contact. The end surface of the rear body 22 is pressed against the opposite side surface of the pump cartridge as a side plate, and the front body 21 and the rear body 22 are integrally assembled. These members constitute the pump component 23.
[0020]
The pressure plate 30 and the rear body 22 serving as a side plate stacked on the pressure plate 30 via a cam ring 27 are integrally assembled in a state of being positioned in the rotational direction by a swing fulcrum pin 31 described later. The swing fulcrum pin 31 functions as a shaft support part and a positioning pin for enabling the cam ring 27 to swing, and also functions as a seal material that defines a fluid pressure chamber for swinging the cam ring 27.
[0021]
32 and 33 are a pump suction side opening and a pump discharge side opening which open into the pump chamber 28, and these openings 32 and 33 are formed by groove portions having a substantially arc shape, and the rotation direction of the rotor 25 as shown in FIG. Are opened in the pump suction side region on the start side and the pump discharge side region on the end side. As shown in FIG. 2, the suction side opening 32 is recessed in the end surface facing the pump chamber 28 of the rear body 22, and the discharge side opening 33 is recessed in the end surface of the pressure plate 30 on the pump chamber 28 side.
[0022]
A groove portion 32 a and a hole portion 32 b having substantially the same shape are formed at positions facing the suction side opening 32 of the pressure plate 30. As shown in FIGS. 4A and 4B, the hole 32 b is connected to a substantially fan-shaped suction-side pressure chamber 34 formed on the bottom side of the storage space 24 of the front body 21. In FIG. 4A, 34 a is an O-ring that surrounds the pressure chamber 34 together with the periphery of the drive shaft 26.
[0023]
The rear body 22 is formed with a suction-side passage 35 that feeds the suction-side fluid sucked from the tank T into the suction-side opening 32 via the suction port 35a. The suction side fluid sucked from the tank T (pump suction side) passes through the pump suction side passage 35 in the rear body 22 from the suction port 35a, and enters the pump chamber 28 from the suction side opening 32 opened to the end face of the rear body 22. Supplied.
[0024]
At the bottom of the storage space 24 of the front body 21, a substantially arc-shaped pump discharge side pressure chamber 36 is formed at a position corresponding to the vicinity of the end of the discharge side opening 33 of the pressure plate 30 in the rotor rotation direction. Yes. The pressure chamber 36 is connected to a discharge port 37a via a pump discharge side passage 37 formed in the front body 21, and is configured to discharge the discharge side fluid pressure guided to the pressure chamber 36 from the discharge port 37a. ing. In FIG. 4A, reference numeral 36 a denotes an O-ring that seals the discharge side pressure chamber 36.
[0025]
In the bottom of the storage space 24 of the front body 21, the portion around the drive shaft 26 excluding the suction-side and discharge-side pressure chambers 34 and 36 is provided with a pump as shown in FIGS. A space 38 into which the fluid pressure on the discharge side is introduced is formed. The space 38 is a volume space having a required volume formed by using the dead space of the front body 21, and the space 38 is discharged through the small hole 38 a formed in the pressure plate 30. It communicates with the side opening 33.
[0026]
The space 38 is a dead-end space connected through a throttle passage by a small hole 38a when viewed from the discharge side passage system of the pump, and attenuates the pressure fluctuation of the fluid pressure on the discharge side of the pump and the noise accompanying this. It functions as a reaction-type resonance chamber.
[0027]
Reference numeral 40 denotes a control valve comprising a valve hole 41 and a spool 42 formed above the front body 21 in a direction orthogonal to the shaft 26, and above a metering throttle 60 provided in the middle of a pump discharge side passage to be described later. , Operated by downstream pressure difference. By means of this control valve 40, first and second fluid pressure chambers 43, 44 which are formed separately on both sides of the cam ring 27 in the adapter ring 29 by the rocking fulcrum pin 31 and a sealing material 45 provided at the axial target position. The fluid pressure to be introduced into the pump is controlled in accordance with the pump rotation speed.
[0028]
A pilot pressure passage 51 (shown by an imaginary line in FIG. 1) is connected to one end side of the valve hole 41 from a space portion 38 into which fluid pressure on the pump discharge side is introduced. A chamber 48 into which the upstream fluid pressure P1 is introduced is formed. On the other end side of the valve hole 41, a spring chamber 46 having a compression coil spring 46a that urges the spool 42 toward the one end side is formed. The spool 42 is urged to the left in FIG. 1 by the spring 46a.
[0029]
Connected to the spring chamber 46 is a pilot pressure passage 52 formed from a portion of the pump discharge side passage 37 that is close to the discharge port 37 a that is a terminal portion of the front body 21, and a fluid pressure downstream of the metering restrictor 60. P2 is derived. A passage 50a is connected to the pump suction side (tank T) in the central portion of the valve hole 41 in the axial direction, and a pump suction side chamber 50 formed by an annular groove 42a at the center of the spool 42 is formed.
[0030]
Here, a pilot throttle 52a may be provided in the middle of the above-described pilot pressure passage 52 as shown by a one-dot chain line in FIG. By providing the pilot throttle 52a, adverse effects such as fluid pressure fluctuations on the spool 42 of the control valve 40 can be prevented. Further, the pilot throttle 52 a reduces the fluid pressure in the spring chamber 46 of the control valve 40 when the relief valve 70 provided in the spool 42 is relieved. Since the cam ring 27 swings in the direction in which the capacity of the pump chamber 28 decreases due to the action of the control valve 40 due to this pressure drop, the pump discharge amount decreases, and in order to save energy of the pump. It will be advantageous.
[0031]
The spring chamber 46 is connected by a connection passage 47 to the second fluid pressure chamber 44 when the spool 42 is in the position shown in FIG. The second fluid pressure chamber 44 is gradually separated from the second fluid pressure chamber 44 when moved in the direction (1). Therefore, the fluid pressure P2 downstream of the metering restrictor 60 and the fluid pressure on the pump suction side are transferred to the spool 42 via the spring chamber 46 and the pump suction side chamber 50. Supplied with the movement of the. A damper throttle 47a is formed in a part of the connection passage 47 described above.
[0032]
The high-pressure side chamber 48 formed on one end side of the spool 42 is closed when the spool 42 is in the position of FIG. 1, but the spool 42 has moved to the spring chamber 46 side (right side in the figure). Sometimes, it is configured to be selectively connected to the first fluid pressure chamber 43 through a connection passage 49 that is gradually disconnected from the pump suction side chamber 50. Therefore, in the first fluid pressure chamber 43, the pump suction side fluid pressure and the upstream fluid pressure P 1 of the metering restrictor 60 are spooled via the pump suction side chamber 50 and the high pressure side chamber 48. Supplied with 42 movements. A damper throttle 49 a is formed in a part of the connection passage 49.
[0033]
In FIG. 1, the connection passage 49 is connected to a pump suction side chamber 50 formed in a central portion in the axial direction of the spool 42 through a gap passage formed by a chamfer portion formed in a land portion on one end side of the spool 42. . Then, depending on the displacement amount of the spool 42, the fluid pressure P1 on the pilot pressure passage 51 side (the fluid pressure on the upstream side of the metering restrictor 60) is selected in the first fluid pressure chamber 43 via the connection passage 49. Connected to each other.
[0034]
Since the differential pressure on the upstream side and the downstream side of the metering restrictor 60 is small at the time of starting the pump or at a low speed, the spool 42 is in the position shown in FIG. 1, and the first fluid pressure chamber 43 is on the pump suction side. Connected and fluid pressure P0 is introduced. On the other hand, the fluid pressure P2 on the pump discharge side downstream of the metering restrictor 60 is introduced into the second fluid pressure chamber 44, and the cam ring 27 is in a state where the volume of the pump chamber 28 is maximized. maintain.
[0035]
When the pump speed is in the middle and high speed rotation range and the discharge flow rate is increased, the spool 42 moves in the direction in which the spring 46a is bent, whereby the chamber 48 to which the pilot pressure passage 51 is connected is connected to the connection passage 49. Will be. As a result, the fluid pressure P1 upstream of the metering restrictor 60 and the fluid pressure P0 in the pump suction side chamber 50 are introduced into the first fluid pressure chamber 43 as the spool 42 moves. .
[0036]
On the other hand, in the second fluid pressure chamber 44, the supply of the fluid pressure P2 downstream of the metering restrictor 60 to the passage 47 is closed by the land portion according to the movement amount of the spool 42. The pump suction side chamber 50 is connected through a gap passage formed by the formed chamfer part. As a result, the second fluid pressure chamber 44 becomes the fluid pressure P0 on the pump suction side, and the cam ring 27 swings and displaces to the right in FIG. 1 as described above, and the volume of the pump chamber 28 decreases.
In the vane type variable displacement pump 20 as described above, configurations other than those described above are as conventionally known, and a specific description thereof is omitted here.
[0037]
In the present embodiment, in the metering throttle 60 for operating the control valve 40 that controls the swinging of the cam ring 27 described above, the discharge amount from the pump 20 when the pump speed reaches the middle and high speed range. Is set to a predetermined flow rate smaller than the maximum discharge flow rate, and the flow rate is maintained, so that a so-called drooping characteristic is provided. As shown in FIGS. 1, 3, 4 (a) and 4 (b), the variable metering diaphragm 61 necessary for this is opposed to the side surface portion 27 c on one side in the axial direction of the cam ring 27. Between the pressure plate 30 and the second fluid pressure chamber 44, the pressure plate 30 is provided at a partitioned position.
[0038]
More specifically, a substantially arc-shaped communication groove 62 communicating with the discharge side opening 33 formed facing the discharge side region of the pump chamber 28 on the inner wall surface 30c of the pressure plate 30 on the pump chamber 28 side, The cam ring 27 is recessed in the side surface portion 27c on one side in the axial direction. Further, a small hole 63 is opened at a position on the inner wall surface 30c of the pressure plate 30 on the pump chamber 28 side so as to face a part of the communication groove 62, and the small hole 63 is formed in a passage hole 64 provided in the pressure plate 30. And connected to the pressure chamber 36 on the pump discharge side. The variable metering diaphragm 61 is configured by forming the small hole 63 so that the opening area can be changed by the groove side edge 62a of the communication groove 62 on the cam ring 27 side. A part of the communication groove 62 passes through the cam ring 27 as shown in FIGS. 1, 3A, 4A, and 4B to maintain the pressure balance on both sides, The passage area can be secured.
[0039]
In such a structure, when the cam ring 27 swings in a direction that decreases the capacity of the pump chamber 28, the opening area of the small hole 63 shown in FIG. 1 is changed from the state of opening in the communication groove 62 to the communication groove 62. It is reduced by being gradually closed by the groove side edge 62a. When the cam ring 27 swings to the left in the drawing as much as possible, the entire small hole 63 is closed and the variable metering diaphragm 61 is closed.
[0040]
In this embodiment, in FIGS. 1, 4A and 4B, a hole 66 is provided on the terminal end side in the rotational direction of the discharge side opening 33, and the discharge side opening 33 and the pressure chamber on the discharge side are provided. 36, and the hole 66 serves as a fixed metering restrictor 65 constituting the metering restrictor 60 to generate a fluid pressure difference for operating the control valve 40.
[0041]
Therefore, when the variable metering restrictor 61 is closed as described above, the control valve 40 is controlled by the pressure difference between the upstream and downstream sides of the fixed metering restrictor 65, and the discharge amount from the pump 20 becomes constant. In this embodiment, the hole 66 serving as the fixed metering restrictor 65 is provided between the discharge side opening 33 and the discharge side pressure chamber 36. However, the present invention is not limited to this. If so, it can be provided at an appropriate position. In short, the fluid pressure on the downstream side of the hole 66 may be guided to the chambers 48 and 46 on both ends of the control valve 40.
[0042]
According to the variable metering restrictor 61 as described above, the portion constituting the variable metering restrictor 61 is formed in a portion partitioned from the second fluid pressure chamber 44 unlike the conventional one, and the jet of pressure fluid flowing through the restrictor 61 Does not affect the fluid pressure in the second fluid pressure chamber 44, so that the cam ring 27 can be swung in a stable state.
In this case, the damper throttle 47a provided in the passage 47 communicating with the pump discharge side of the second fluid pressure chamber 44 is similar to the damper throttle 49a provided in the passage 49 on the first fluid pressure chamber 43 side. It functions to prevent fluid pressure fluctuations and consequently suppress unwanted movement of the cam ring 27.
[0043]
That is, the first and second fluid pressure chambers 43 and 44 for swinging the cam ring 27 are placed in the middle of the control valve 40 and the pump discharge side passage through the damper restrictors 49a and 47a and above the metering restrictor 60. Since it is connected to the downstream side, when the cam ring 27 swings with the pressure difference of the fluid pressure on the downstream side of the metering throttles 61 and 65 due to increase or decrease of the pump rotation speed, Thus, a required braking force can be applied in both swing directions. Accordingly, since an appropriate braking force can be applied when swinging toward the first and second fluid pressure chambers 43 and 44, the cam ring 27 does not vibrate or pulsate on the pump discharge side. It can be swung smoothly in the state.
[0044]
Thus, the first and second fluid pressure chambers 43 and 44 having a damper function cause the cam ring 27 to swing in a required state in accordance with the magnitude of the flow rate on the pump discharge side, thereby supplying the flow rate to the pump discharge side. As shown by the solid line in FIG. 8 described above, it can be maintained at a constant amount or an arbitrary amount equal to or less than a constant amount as the pump rotational speed increases. Such a constant amount is an amount defined by the hole 66 that forms the fixed metering restrictor 65 described above, and flow control beyond that is defined by the opening area of the small hole 63 that forms the variable metering restrictor 61. Amount.
[0045]
The present invention is not limited to the structure described in the above-described embodiment, and the shape and structure of each part of the variable displacement pump 20 can be freely modified and changed as appropriate, and various modifications can be considered. For example, in the above-described embodiment, the case where one small hole 63 is used as the hole portion constituting the variable metering diaphragm 61 is illustrated, but the present invention is not limited to this, and FIG. 5 and FIG. As shown in (b) and (c), the hole may be constituted by a plurality (three in this case) of small holes 63. If the plurality of small holes 63 are used and the opening area is changed at the groove side edge 62a of the communication groove 62, the amount of change in the opening area due to the swinging displacement of the cam ring 27 is larger than that of one. Can be set.
[0046]
FIG. 5 shows an example in which the communication groove 62 on the cam ring 27 side is formed as an annular groove formed on the entire circumference of the side surface portion 27c of the cam ring 27 instead of an arc-shaped groove. If it forms in this way, a process can be performed easily. In addition, as a hole part which comprises such a variable metering stop 61, you may form with the hole which has not only the circular hole demonstrated in embodiment mentioned above but appropriate cross-sectional shape.
[0047]
In the above-described embodiment, the example in which the small hole 63 constituting the variable metering diaphragm 61 is formed in the inner wall surface of the pressure plate 30 facing the side surface portion of the cam ring 27 has been described, but the pump body is not used without using the pressure plate. When the inner wall portion directly faces the cam ring 27, the small hole may be provided in the inner wall portion. Further, the small hole 63 constituting the variable metering diaphragm 61 and the groove side edge 62a of the communication groove 62 can be provided at positions opposite to those of the above-described embodiment.
[0048]
In the embodiment described above, the variable metering diaphragm 61 and the fixed metering diaphragm 65 are separately formed as the metering diaphragm portion 60 so that the opening area of the variable metering diaphragm 61 is changed from the fully open state to the fully closed state. Although the case where the structure is changed to have been described, the present invention is not limited to this. Using a hole with one or more small holes as a metering diaphragm, a part of this hole is always fully opened to function as a fixed diaphragm, and the remaining aperture area functions as a variable diaphragm The structure to be made may be sufficient. Further, in the above-described embodiment, the fixed metering diaphragm 65 and the variable metering diaphragm 61 constituting the metering diaphragm unit 60 are simply described as “throttles”, but this is because such a throttle portion is an orifice. This is because chalk may be used.
[0049]
Further, the above-described embodiment shows an example of the variable displacement pump 20, and it is free to modify and change parts other than the variable metering restrictor 60, which is a main part of the present invention. is there. For example, the structures of the suction side passage 35 and the discharge side passage 37 in the pump bodies 21 and 22 may be changed as appropriate. Further, the control valve 40 may have a structure that can ensure a pressure difference between the first and second fluid pressure chambers 43 and 44 in order to swing the cam ring 27.
[0050]
【The invention's effect】
As described above, according to the variable displacement pump according to the present invention, the variable metering restrictor for operating the control valve is provided in the partitioned portion that does not affect the fluid pressure in the second fluid pressure chamber. Since it is provided, the cam ring can be swung in a state in which this second fluid pressure chamber has a damper function. Therefore, the cam ring can be swung by operating the damper function in the fluid pressure chambers on both sides in the swing direction of the cam ring, reducing the vibration of the cam ring and pulsation on the pump discharge side, and the supply flow rate with respect to the pump rotation speed. Characteristics can be improved.
[Brief description of the drawings]
FIG. 1 shows an embodiment of a variable displacement pump according to the present invention, and is a cross-sectional view of the main part of the pump during low rotation.
FIG. 2 is a cross-sectional view taken along the line II-II in FIG.
3A is a cross-sectional view taken along line IIIa-IIIa in FIG. 1, and FIG. 3B is a cross-sectional view taken along line IIIb-IIIb in FIG.
4A is a cross-sectional view taken along line IVa-IVa in FIG. 2, and FIG. 4B is a cross-sectional view taken along line IVb-IVb in FIG.
FIG. 5 is a side view showing another embodiment of the variable displacement pump according to the present invention and showing a surface of the pressure plate facing the pump chamber.
FIGS. 6A and 6B are enlarged views of the VI part of FIG. 5, in which FIGS. 5A, 5B, and 5C change the opening area of a small hole that forms a variable metering diaphragm as the cam ring swings. It is a figure for demonstrating the state to do.
FIG. 7 is a diagram illustrating the operation of the conventional variable displacement pump in a state of low rotation.
FIG. 8 is a characteristic diagram for explaining the relationship between the supply flow rate Q and the pump rotation speed N in the variable displacement pump.
[Explanation of symbols]
20 ... Vane type variable displacement pump (variable displacement vane pump), 21 ... Front body (pump body), 22 ... Rear body (pump body), 23 ... Pump components, 24 ... Storage space, 25 ... Rotor, 25a ... Vane, 26 ... Drive shaft (rotating shaft), 27 ... Cam ring, 27b ... Compression coil spring (biasing means), 28 ... Pump chamber, 29 ... Adapter ring, 30 ... Pressure plate, 31 ... Swing fulcrum pin, 32 ... Suction side opening 33 ... Discharge side opening 34 ... Pump suction side pressure chamber 35 ... Suction side passage 35a ... Suction port 36 ... Pump discharge side pressure chamber 37 ... Discharge side passage 37a ... Discharge port 38 ... Space (resonance chamber), 40 ... spool type control valve, 41 ... valve hole, 42 ... spool, 42a ... annular groove, 43, 44 ... first and second flow Pressure chamber, 45 ... Sealing material, 46 ... Spring chamber, 46a ... Compression coil spring, 47 ... Connection passage, 47a ... Damper throttle, 48 ... High-pressure side chamber, 49 ... Connection passage, 49a ... Damper throttle, 51 ... Pilot pressure Passage, 51a ... damper throttle, 52 ... pilot pressure passage, 52a ... pilot throttle, 60 ... metering throttle, 61 ... variable metering throttle, 62 ... communication groove, 62a ... groove side edge, 63 ... small hole (hole) , 64 ... passage hole, 65 ... fixed metering throttle, 66 ... hole, PS ... pressure fluid utilization device (power cylinder of power steering device), T ... tank.

Claims (1)

A cam ring forming a pump chamber is supported so as to be swingable in the internal space of the pump body, a first fluid pressure chamber is formed on one side of the swing direction of the cam ring, and a second fluid pressure chamber is formed on the other side. And a biasing means for biasing the cam ring in a direction in which the pump capacity of the pump chamber is maximized, and a variable metering provided in the middle of the discharge side passage of the pressure fluid discharged from the pump chamber The variable displacement pump is provided with a control valve that operates according to a fluid pressure difference on the downstream side of the throttle, and controls the fluid pressure in at least the first fluid pressure chamber by the control valve to swing the cam ring. the metering throttle, the recessed in the side surface portion of one side in the axial direction of the cam ring, or is formed through the axial direction so as to open on the side surface of one side of the cam ring the side surface portion A communication groove communicating with the discharge side opening of the pump chamber formed in the side wall portion of the pump body that faces the pump body, and is opened at a position facing the part of the communication groove on the side wall portion of the pump body. A variable displacement pump characterized in that it is formed from a hole portion whose opening area can be adjusted by a groove side edge of the communication groove, and is provided at a position partitioned from the second fluid pressure chamber.

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