JP2000136781A - Variable displacement pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a variable metering orifice in a simple structure for relatively displacing a cam ring to a rotor in a variable displacement pump. SOLUTION: A cam ring 17 defining a pump chamber in a body 11 spaced from the rotor 15 is arranged in a displaceable manner and energized so as to keep the pump capacity of the pump chamber 18 to a maximum. A selector valve 30 is provided to be operated with a pressure difference between the upstream and downstream sides of a variable metering orifice 40 provided on the way of pump discharge side passages 20a, 28 for controlling fluid pressure in first and second fluid pressure chambers 43, 44. The variable metering orifice has a hole portion 29 made in a plate arranged on the side face of the cam ring for connecting a pump discharge side to an annular gap space between the cam ring and a rotor and a cam ring side portion for changing the opening area at the opening end of the hole portion with the movement of the cam ring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vane type variable displacement pump suitable for use in, for example, a power steering device for reducing the steering force of an automobile.

[0002]

2. Description of the Related Art A displacement type vane pump generally used as a pump for a power steering device is directly driven to rotate by an automobile engine, and the higher the engine speed, the larger the discharge flow rate. On the other hand, a power steering device requires a higher steering assist force when the vehicle is stopped or running at low speed, while reducing the steering assist force during high speed running conversely reduces running stability and steering. Desired from the viewpoint of feeling.

For this reason, in the conventional displacement type pump, a pump capable of securing a discharge flow rate to obtain a required steering assist force when the rotation speed is in a low rotation range is used, and the rotation speed is set in a high rotation range. In some cases, a flow control valve for recirculating a part of the discharge flow rate to the tank side is provided. In addition, the flow rate supplied to the power steering device is controlled to be constant irrespective of the number of revolutions of the engine, or the flow rate is controlled so that the flow rate is lower in a high speed range than in a low speed range.

However, in such a conventional displacement pump, it is necessary to provide a flow control valve, and the structure of the whole pump is complicated, which not only increases the size but also increases the cost. Was. Further, in such a conventional displacement pump, the flow rate to be recirculated to the tank side becomes larger as the engine speed becomes higher, which is a problem in terms of energy loss.

[0005] Therefore, as a pump used for this type of power steering device, for example, Japanese Patent Application Laid-Open No. 53-130 is known.
Japanese Patent Application Laid-Open No. 505-505, Japanese Patent Application Laid-Open No. Sho 56-143383, and the like have already proposed variable displacement pumps in which the discharge flow rate of the pump itself can be reduced stepwise as the number of revolutions increases. However, such a variable displacement pump eliminates the need to use the above-described flow control valve.

In the variable displacement pump, the eccentricity between the center of the rotor of the vane pump and the center of the cylindrical cam surface on which the vane slides is variable, and the communication area of the variable metering orifice provided in the pump discharge passage is small. The cam ring having a cylindrical cam surface is configured to decrease in response to a displacement in a direction to reduce the amount of eccentricity. And
By controlling the movement of the cam ring using the differential pressure on the downstream side of the variable metering orifice, the pump capacity of the pump chamber is reduced, and the discharge flow rate is reduced with the increase in the rotation speed of the rotor. Met.

Further, in the latter variable displacement pump, a cam ring is configured to be movable, and a pair of control chambers is formed in a gap formed between the cam ring and the pump casing. By guiding the fluid pressure on the downstream side of the variable metering orifice and applying the differential pressure directly to the cam ring and moving it appropriately against the urging force of the spring, it is possible to perform appropriate discharge flow rate control Was what it was.

However, according to the above-described conventional variable displacement pump, the cam ring is held so as to be linearly movable in the pump housing, and this is directly above or downstream of the variable metering orifice provided directly or indirectly in the discharge passage. It was only operated by the differential pressure on the side, and had problems in workability, operational reliability, and durability, and was poorly feasible.

Japanese Patent Application Laid-Open Nos. 58-93978 and 63-14078 disclose that a cam ring is linearly displaceable in a radial direction in a pump housing, and a pump chamber is provided in the cam ring. A rotor for forming is rotatably housed, and a cam ring is displaced relative to the rotor with a pressure difference on the downstream side above a variable metering orifice provided in the pump discharge passage,
There is disclosed a variable displacement pump capable of changing the flow area of the variable metering orifice in response to the amount of eccentricity of the cam ring with respect to the rotor and varying the discharge flow rate to obtain a desired flow rate.

Particularly, in the latter conventional example, a control pin having a small diameter portion is interposed between an inner wall portion of the pump housing and an outer peripheral portion of a cam ring which can be displaced inside the pump housing, and the small diameter portion of the control pin and the cam ring The variable metering orifice is constituted by the control surface of the outer peripheral portion. A variable metering orifice is formed in which the fluid pressure on the downstream side of the variable metering orifice acts on the cam ring to displace the cam ring, and the opening area decreases as the eccentric amount of the cam ring decreases. As a result, a desired discharge flow rate was obtained.

[0011]

However, in such a conventional structure, the structure of the portion forming the variable metering orifice for moving and displacing the cam ring is complicated, the number of parts is large, and the processing accuracy of each part is also high. It is difficult and causes problems in terms of processing and assemblability.

Further, according to the conventional variable metering orifice described above, there is a problem in reliability in operation as the variable metering orifice. That is, in the conventional variable metering orifice, it is difficult to variably control the passage area according to the increase or decrease of the discharge flow rate of the pump. As a result, the discharge flow rate is determined by the differential pressure on the upstream and downstream sides of the variable metering orifice. There is a problem that it is difficult to control to a required state.

The present invention has been made in view of such circumstances. For example, in a vane type oil pump, a cam ring is moved to change a discharge flow rate per one rotation in accordance with a change in the number of rotations of the pump. A variable metering orifice for obtaining a pressure difference for actuating a switching valve for controlling a fluid pressure in the first and second fluid pressure chambers to be displaced is constituted by a simple structure, and further, interlocked with a change in the pump capacity of the pump chamber. It is an object of the present invention to obtain a variable displacement pump that can reliably change the opening area of the variable metering orifice and has high operational reliability.

[0014]

In order to meet such an object, a variable displacement pump according to the present invention has a pump chamber formed between the pump and a rotor and is disposed so as to be movable within a pump body. A cam ring that forms a first fluid pressure chamber on one side of the movement direction with the body and a second fluid pressure chamber on the other side, and biases the cam ring in a direction that maximizes the pump capacity of the pump chamber. Biasing means, a variable metering orifice provided in the pump body in the middle of the pump discharge side passage, and first and second fluid pressures actuated by a pressure difference between the upstream and downstream of the variable metering orifice. In a variable displacement pump having a switching valve for controlling a fluid pressure in a chamber, a side surface of a cam ring in which the variable metering orifice is movably disposed within the pump body. A hole which is formed in a side wall portion arranged in the side wall to connect a pump discharge side to an annular gap space between a cam ring and a rotor; and a cam ring which changes an opening area of an opening end of the hole in accordance with movement of the cam ring. It is characterized by comprising the side part.

According to the present invention, the cam ring has the first and second cam rings.
Due to the displacement of the fluid inside the pump body due to the pressure difference of the fluid pressure in the fluid pressure chamber and the urging force of the urging means, the opening area of the hole opening in the side wall of the pump body on the side of the cam ring changes. And functions as a variable metering orifice.

[0016]

1 to 5 show an embodiment of a variable displacement pump according to the present invention. In these figures, in this embodiment, a vane serving as a hydraulic pressure source of a power steering device is shown. A case of a type oil pump will be described.

A vane-type variable displacement pump generally designated by the reference numeral 10 is, as apparent from FIGS.
A pump body includes a front body 11 and a rear body 12. The front body 11 has a substantially cup shape as a whole, and includes a pump component 13 therein.
Is formed, and the rear body 12 is combined and integrated so as to close the open end of the storage space 14. The bearing 16a, 1 is inserted into the front body 11 in a state where a drive shaft 16 for externally driving a rotor 15 as a rotor of the pump component 13 is rotated.
6b, 16c (16b is disposed on the rear body 12 side, 16c is disposed on the pressure plate 20 side described later), and is rotatably supported.

Reference numeral 17 denotes a cam ring having an inner cam surface 17a fitted and arranged on the outer peripheral portion of the rotor 15 having the vane 15a. A pump chamber 18 is formed between the inner cam surface 17a and the rotor 15. I have. This cam ring 1
As described later, 7 is arranged so as to be movable and displaceable within an adapter ring 19 provided in the storage space 14 in a fitted state on the inner wall portion of the space so as to change the volume of the pump chamber 18. The adapter ring 19 holds the cam ring 17 so as to be movable and displaceable in the storage space 14 of the body 11, and also has a fluid passage 1 described later between the adapter ring 19 and the inner wall of the body.
9a.

Reference numeral 20 denotes a pressure plate. The pressure plate 20 includes the rotor 15 and the cam ring 1 described above.
The pump cartridge, which is composed of the pump cartridge 7 and the adapter ring 19, is arranged in pressure contact with the front body 11 side of the pump cartridge. The end face of the rear body 12 is pressed against the opposite side face of the pump cartridge as a side plate, and a required assembly state is obtained by integrally assembling the bodies 11, 12. The pump component 13 is constituted by these members. The pressure plate 20 and the rear body 12 serving as a side plate laminated on the pressure plate 20 via the cam ring 17 are formed by a seal pin 21 which also functions as a positioning pin and an appropriate detent means (not shown) which will be described later. They are integrally assembled and fixed while being positioned in the rotation direction.

Reference numeral 23 denotes a pump discharge side pressure chamber formed at the bottom side in the storage space 14 of the front body 11 so as to apply a pump discharge side pressure to the pressure plate 20. Reference numeral 24 denotes a pump discharge side passage formed in the pressure plate 20 for guiding the pressure oil from the pump chamber 18 to the pump discharge side pressure chamber 23.

Reference numeral 25 denotes a pump suction side formed in the rear body 12 so as to guide a pump suction side fluid from a suction port 26 (not shown in detail) provided in a part of the rear body 12 to the pump chamber 18. In the passage, this passage 25
Is a pump suction opening 2 which is opened on the end face of the rear body 12.
It is connected to the pump chamber 18 via 5a.

Reference numeral 28 denotes a discharge port.
The pump chamber 18 is connected to the pump discharge side passage 24, the pump discharge side pressure chamber 23, and the pressure plate 20
A part for supplying hydraulic pressure such as a power steering device (indicated by PS in the figure) such as a power steering device (indicated by PS in the figure) which is supplied through a fluid passage 20a and a small-diameter hole portion 29 formed in different positions. is there. This discharge port 28
A variable metering orifice 40 is provided on a side portion of the front body 11 at a portion connected to the storage space 14.

Reference numeral 30 denotes a switching valve. The switching valve 30 is disposed substantially orthogonally to the side of the storage space 14 in the front body 11, and is a fluid pressure for moving and displacing the cam ring 17 with respect to the rotor 15. The control is performed by a variable metering orifice 40 described later. This switching valve 30 is
A spool 32 is slid by a fluid pressure difference and the urging force of a spring 31 in a valve hole 30a formed in the body 11 from the side.

In the switching valve 30, one side chamber (left chamber in FIG. 1) 32a of the spool 32 is provided upstream of a variable metering orifice 40 described later from the pressure chamber 23 on the pump discharge side via a fluid passage 23a. Side fluid pressure is directed. In the figure, reference numeral 33 denotes a plug for closing the valve hole 30a having a rod 33a for locking the leftward movement position of the spool 32 in the valve hole 30a at a position that does not close the open end of the fluid passage 23a.

A spring 31 is provided in the other chamber (right chamber in FIG. 1) 32b of the spool 32, and fluid pressure downstream of the variable metering orifice 40 reaches the discharge port 28. The body 1 from the middle of the passage
1. Fluid passage 19 formed between adapter rings 19
a, it is guided through a fluid passage 34 formed in the body 11.

Further, at a substantially central portion of the valve hole 30a,
Suction side passage 2 branched from the pump suction side passage 25
7 is open. The adapter ring 19 and the cam ring 17 are provided on both axial sides of the valve hole 30a.
Fluid passages 35, 36 (passage holes 3 of the adapter ring 19) from a plurality of divided chambers (first and second fluid pressure chambers 43, 44 described later) of an annular gap space formed between
5a and 36a) are open. These passages 3
5 and 36 are selectively connected to the pump suction side passage 27, the left chamber 32a or the right chamber 32b by the movement of the spool 32.

Most of the configuration of the above-described vane type variable displacement pump 10 is well known in the art, and a detailed description thereof will be omitted.

The variable displacement pump 10 having the above configuration
In the above, the cam ring 17 forming the pump chamber 18 between itself and the outer periphery of the rotor 15 so as to be movable and displaceable in the bodies 11 and 12 is provided with a pump capacity (volume) of the pump chamber 18 via a cylindrical pressing member 41. And a pump discharge side passageway (2).
4, 23, 20a, 29, 28) Sealing means interposed at a predetermined position in the annular gap space between the variable metering orifice 40 provided in the middle and the body 11 (adapter ring 19) at the outer periphery of the cam ring 17 (21, 47) which selectively displaces the cam ring 17 by selectively introducing the fluid pressure on the downstream side or the fluid pressure in the pump suction side passage 27 above and below the variable metering orifice 40. For the second fluid pressure chambers 43, 44 and the first and second fluid pressure chambers 43, 44, the fluid pressure on the upstream and downstream sides of the variable metering orifice 40 and the fluid pressure on the pump suction side are selectively selected. And a control switching valve 30 for switching and introducing the control valve.

In this embodiment, the switching valve 30 selectively selects the fluid pressure upstream of the variable metering orifice 40 on the pump discharge side or the fluid pressure on the pump suction side with respect to the first fluid pressure chamber 43. And the pump pressure on the pump suction side or the fluid pressure on the downstream side of the variable metering orifice 40 is selectively introduced into the second fluid pressure chamber 44 so that the pressure in each of the fluid pressure chambers 43 and 44 is increased. Controls fluid pressure.

Further, in this embodiment, in order to divide the annular gap space between the cam ring 17 and the adapter ring 19, as shown in FIG. The first seal pin 21 which also functions as the above-described positioning pin, which is positioned so as to be divided into right and upper positions, and the groove formed in the sliding contact surface of the cam ring 17 with a resin sheet interposed therebetween. A second sealing pin 47 is provided. A space on one side (left side in the drawing) of the moving direction of the cam ring 17 is defined as a first fluid pressure chamber 43, and the first fluid pressure chamber 43 is variable in the switching valve 30 via the fluid passages 35a and 35. Left chamber 32a or spool 32 to which the upstream side of metering orifice 40 is connected
And is connectable to a chamber formed substantially at the center and connected to the pump suction side.

Further, in the space on the other side in the moving direction of the cam ring 17 on the right side in FIG. 1, the third seal pin 48 is attached to the outer periphery of the cam ring 17 at a position above the variable metering orifice 40 reaching the discharge port 28. The upper right space in the drawing is divided into a second fluid pressure chamber 44 which is connected to the pump suction side of the switching valve 30 via the fluid passages 36a and 36. Chamber or right chamber 32 to which the downstream side of variable metering orifice 40 is connected.
b.

In this embodiment, a space portion on the other side (upper right in the figure) of the moving direction of the cam ring 17 in the above-mentioned annular gap space and on the lower right side in the figure other than corresponding to the second fluid pressure chamber 44 In addition, a third fluid pressure chamber 45 is formed by the first seal pin 21 and the third seal pin 48. The third fluid pressure chamber 45 is formed on the right side of the seal pin 21 in the drawing and corresponds to a portion corresponding to the pump discharge side area in the pump chamber 18.

The fluid pressure on the downstream side of the variable metering orifice 40 in the pump discharge side passage is guided to the third fluid pressure chamber 45. That is, since the third fluid pressure chamber 45 is provided with the hole 29 that constitutes the variable metering orifice 40, the inside of the chamber 45 has a fluid pressure downstream of the variable metering orifice 40. I have. The third fluid pressure chamber 45 is
A passage 19a formed outside the adapter ring 19;
The passage 34 is connected to the right chamber 32 b of the switching valve 30.

According to the present invention, the variable metering orifice 40 is bored in the pressure plate 20 which is a side wall disposed on the side surface of the cam ring 17 so that the variable metering orifice 40 is formed between the pump discharge side and the third annular clearance space. It comprises a hole 29 connecting the fluid pressure chamber 45 and a side surface of the cam ring 17 for changing the opening area of the opening end. And
The cam ring 17 includes first and second fluid pressure chambers 43 and 44.
The side surface of the cam ring 17 closes the hole 29 in accordance with the amount of displacement when the cam ring 17 moves due to the fluid pressure difference inside,
The opening area can be reduced or enlarged, and the function as the variable metering orifice 40 can be exhibited.

Here, the third seal pin 48 described above is used.
1 and 3, regardless of the amount of displacement of the cam ring 17, the upper and lower chambers 44,
45 is held with a biasing force and a guide amount in a direction in which the 45 can be appropriately partitioned, and for example, a fluid pressure or the like may be used as the above-described biasing force. However, the present invention is not limited to this. For example, a spring 48a or the like may be used as shown in FIG. The point is that the third seal pin 48 moves following the movement of the cam ring 17 so that the sealing property at that portion can be ensured.

On the other hand, the above-described cylindrical pressing member 41 is formed.
As is clear from FIGS. 1, 2 and 4, a guide hole 19 formed in a part of the outer peripheral portion of the adapter ring 19 is provided.
1B, the cam ring 17 is arranged so as to be able to advance and retreat in the centrifugal direction with respect to the cam ring 17 and is interposed between the cam ring 17 and the discharge port 28. It is configured to be constantly pressed to the middle left. Such a pressing member 41
As a result, the flow of the fluid to the discharge port 28 and the variable metering orifice 4
If the shape does not interfere with the hole 29 constituting the 0,
It may have any shape.

According to the above configuration, when the pump 10 is started, the cam ring 17 has one side in the storage space 14 of the body 11 and the pump capacity of the pump chamber 18 between the cam ring 17 and the rotor 15 as shown in FIG. Coil spring 4 so that it becomes maximum
2. In a state of being urged by the pressing member 41. At this time, the switching valve 30 moves the first fluid pressure chamber 43 to the pump suction side and the second fluid pressure chamber 4 as shown in FIG.
4 is connected to the downstream side of the variable metering orifice 40 on the pump discharge side.

At this time, the fluid pressure on the downstream side of the variable metering orifice 40 is introduced into the third fluid pressure chamber 45 through the hole 29 which constitutes the variable metering orifice 40 and has the largest opening area. Since this fluid pressure is also higher than the fluid pressure of the first fluid pressure chamber 43, the cam ring 17 is connected to the first fluid pressure chamber 4 as described above.
It is moved and displaced to the third side.

When the pump speed is gradually increased and the pump is driven, the fluid pressure on the upstream side of the variable metering orifice 40 on the pump discharge side is changed by the pressure difference between the fluid pressure on the downstream side and the switching valve 30. The spool 32 is actuated, whereby the first fluid pressure chamber 4 on one side in the moving direction of the cam ring 17 is moved.
3, the fluid pressure upstream of the orifice 40 is introduced, and the second fluid pressure chamber 44 on the other side is connected to the pump suction side, so that the cam ring 17 resists the urging force of the coil spring 42. It moves and displaces in the direction in which the pump capacity of the pump chamber 18 decreases (the right side in FIGS. 1 and 3).

At this time, in the third fluid pressure chamber 45, the variable metering which passes through the hole 29 whose opening area is reduced by being directly closed by the side surface portion with the movement displacement of the cam ring 17 is provided. Fluid pressure downstream of the orifice 40 is introduced. This fluid pressure is applied to the variable metering orifice 40 introduced into the first fluid pressure chamber 43.
Is lower than the fluid pressure on the upstream side, and as a result, the cam ring 17 has a fluid pressure difference between the first fluid pressure chamber 43 and the second and third fluid pressure chambers 44 and 45 as described above. As a result, it is displaced toward the second and third fluid pressure chambers 44 and 45.

When the switching valve 30 operates as described above, the second fluid pressure chamber 44 located on the opposite side of the first fluid pressure chamber 43 is connected to the pump suction side. The pressure difference between the fluid pressure on the upstream side of the variable metering orifice 40 introduced into the first fluid pressure chamber 43 and
The cam ring 17 moves and displaces in a required state. As a result, the opening / closing amount of the side of the cam ring 17 with respect to the opening end of the hole 29 is changed as is apparent from FIG. 5, and the opening area of the variable metering orifice 40 is varied.
By obtaining a stable movement displacement of the cam ring 17, it becomes possible to obtain a predetermined flow rate reaching the power steering device PS.

In particular, according to the above-described configuration, the switching valve 30 is controlled by the differential pressure generated in the variable metering orifice 40 by the pump discharge amount which increases and decreases with the pump rotation speed.
, Whereby the cam ring 17 can be moved and displaced against or in accordance with the urging force of the coil spring 42. As a result, the pump capacity of the pump chamber 18 is variably controlled, For example, as shown in FIG. 5, the discharge amount from the pump can be balanced in accordance with the pump rotation speed, and can be controlled to obtain desired characteristics.

That is, the variable metering orifice 4
As shown in FIG. 5, when the rotation speed is low, the hole 29 constituting 0 is raised so that a predetermined flow rate can be obtained by the opening area which is changed by being closed by the cam ring 17. When this happens, the flow rate may be reduced, and at a predetermined rotational speed or more, a flow rate of about half of the initial flow rate may be obtained.

Here, such discharge amount control is performed by controlling the hole 2
9, which is obtained by a variable metering orifice 40 formed by a cam ring 17 for controlling the opening amount thereof.
For example, the characteristics can be changed by arbitrarily changing the shape of the hole 29 or adjusting the opening degree control amount of the opening area by the cam ring 17. In addition, the above-described cam ring 17 is a member that follows the pump capacity of the pump chamber 18, and a hole 29
Since the opening area is directly changed, the operation reliability as the variable metering orifice 40 is excellent.

The variable displacement pump 10 having the above structure
According to the first embodiment, the displacement caused by the swing of the cam ring 17 about the seal pin 21 for controlling the flow rate by the variable metering orifice 40 as described above is provided on one side of the movement direction of the cam ring 17. Room 43
The fluid pressure on the upstream side of the variable metering orifice 40 is guided to the second fluid pressure chamber 44 formed on the other side in the moving direction. , 44, the cam ring 17 is easy to move. In the above-described structure, the third fluid pressure chamber 45 located on the other side in the moving direction of the cam ring 17 together with the second fluid pressure chamber 44 has:
Since the fluid pressure on the downstream side of the variable metering orifice 40 is guided, the cam ring 17 also moves in the above-described direction due to the fluid pressure difference between these chambers 43 and 45.

Therefore, for example, even if the pump discharge pressure becomes high and the bodies 11 and 12 are deformed or deformed, or dust or the like is mixed in the fluid and intervenes at a position where the movement of the cam ring 17 is prevented. The force for moving the cam ring 17 can be obtained by a pressure difference between the pump discharge pressure and a sufficiently small pump suction pressure.
Can be moved and displaced lightly with a strong force. In this case, a predetermined flow rate can be obtained stably, and the differential pressure on the upstream and downstream sides of the variable metering orifice 40 can be small, so that power consumption can be reduced.

It should be noted that the present invention is not limited to the structure of the above-described embodiment, and the shape, structure, etc. of each part constituting the variable displacement pump 10 can be freely modified and changed. Needless to say, a modified example may be adopted.
Further, in the above-described embodiment, the case where the hole 29 for changing the opening area on the side surface of the cam ring 17 constituting the variable metering orifice 40 is formed in the pressure plate 20 disposed on the side surface of the cam ring 17 is described. However, the present invention is not limited to this, and may be a hole formed in a side wall of a body or another plate facing the side surface of the cam ring 17.

Further, the structure of the vane type variable displacement pump 10 having the above-described configuration is not limited to the structure of the above-described embodiment. It goes without saying that the present invention may be applied to various devices and apparatuses.

[0049]

As described above, according to the variable displacement pump according to the present invention, since the variable metering orifice is constituted by the hole whose opening area changes directly by the movement of the cam ring, the number of extra parts is reduced. , And can be configured with a minimum number of components, the structure is simple, and the cost is low.

Further, according to the present invention, the pump discharge flow rate is made variable in accordance with the change in the pump speed, and the cam ring can be easily and appropriately displaced in a required state. The desired discharge flow rate according to the pump speed can be obtained by increasing or decreasing the opening area of the hole constituting the variable metering orifice for flow rate adjustment to a required state. Therefore, it is also excellent in reliability in operation as a variable metering orifice.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment of a variable displacement pump according to the present invention and showing a main structure of the pump.

FIG. 2 is a vertical cross-sectional view of a main part shown for explaining the main part structure of FIG. 1;

FIG. 3 is a schematic cross-sectional view for explaining a state when the pump is driven from FIG.

FIG. 4 is a schematic perspective view showing an example of a pressing member for pressing and biasing a cam ring.

FIG. 5 is a characteristic diagram for explaining a relationship between a rotation speed and a flow rate in the pump according to the present invention.

FIG. 6 is an enlarged view of a main part showing a modification of the present invention.

[Explanation of symbols]

10: Vane type variable displacement pump, 11: Front body, 12: Rear body, 13: Pump components, 1
4 ... storage space, 15 ... rotor, 15a ... vane, 16 ...
Drive shaft, 17: Cam ring, 17a: Cam surface, 18: Pump chamber, 19: Adapter ring, 20: Pressure plate, 21: Seal pin, 23: Pump discharge side pressure chamber, 23a: Pump discharge side passage, 25: Pump suction Side passage, 28 discharge port, 29 hole forming variable metering orifice, 30 switching valve, 3
2 ... spool, 34 ... fluid passage, 35 ... passage hole, 36 ...
Passage hole, 40: variable metering orifice, 42: coil spring (biasing means), 43: first fluid pressure chamber, 44:
Second fluid pressure chamber, 45... Third fluid pressure chamber, 47... Second seal pin, 48.

Claims (1)

[Claims] A first fluid pressure chamber is formed on a side of a moving direction between the pump body and a pump chamber.
A cam ring forming a second fluid pressure chamber on the other side; an urging means for urging the cam ring in a direction in which the pump capacity of the pump chamber is maximized; and a midway of a pump discharge side passage in the pump body. A variable metering orifice provided, and a switching valve that operates by a pressure difference between the upstream and downstream of the variable metering orifice to control the fluid pressure in the first and second fluid pressure chambers. In the pump, the variable metering orifice is bored in a side wall portion arranged on a side surface portion of a cam ring movably displaceable in the pump body to connect a pump discharge side to an annular gap space between the cam ring and the rotor. And a cam ring side surface portion that changes an opening area of an opening end of the hole according to the movement of the cam ring. Variable displacement pump.