JP3481642B2 - Variable displacement pump - Google Patents

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 vane pump, which is generally used as a pump for a power steering apparatus, is directly driven by an automobile engine to rotate. The higher the engine speed, the larger the discharge flow rate. On the other hand, the power steering device requires a higher steering assist force when the vehicle is stopped or traveling at a low speed, while reducing the steering assist force when traveling at a high speed, in contrast to the traveling stability and steering. It is desired from the viewpoint of feeling.

For this reason, in the conventional displacement pump, a pump capable of ensuring a discharge flow rate so as to obtain a required steering assist force when the rotation speed is in the low rotation speed range is used, and the rotation speed is in the high rotation speed range. In some cases, a flow rate control valve is provided for returning a part of the discharge flow rate to the tank side. Then, the flow rate supplied to the power steering apparatus is controlled to be constant regardless of the number of revolutions of the engine, or the flow rate is controlled to be smaller in the high rotation range than in the low rotation range.

However, in such a conventional displacement type pump, it is necessary to attach a flow rate control valve, and the structure of the entire pump is complicated, which not only leads to an increase in size but also an increase in cost. It was Further, in such a conventional displacement pump, the flow rate to be recirculated to the tank side becomes larger in the high engine speed region, which is a problem in terms of energy loss.

Therefore, as a pump used for this type of power steering apparatus, for example, Japanese Patent Laid-Open No. 53-130.
Japanese Patent Laid-Open No. 505 and JP-A-56-143383 have already proposed a variable displacement pump configured so that the discharge flow rate of the pump can be decreased stepwise as the rotation speed increases. In such a variable displacement pump, it is not necessary to use the above-mentioned flow rate control valve.

In the former variable displacement pump, the eccentric amount between the rotor center 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 large. The cam ring having a cylindrical cam surface is configured to become smaller in response to the displacement in the direction of reducing the eccentric amount. And
By controlling the movement of the cam ring using the differential pressure on the upstream side and the downstream side of this variable metering orifice, the pump capacity of the pump chamber is reduced and the discharge flow rate is reduced with the increase of the rotation speed of the rotor. Met.

Further, in the latter variable displacement pump, the cam ring is configured to be movable, and a pair of control chambers are formed in a gap portion formed between the cam ring and the pump casing, each of which has a discharge passage. By guiding the fluid pressure on the upstream and downstream sides of the variable metering orifice and acting the differential pressure directly on the cam ring to move it appropriately against the biasing force of the spring, it is possible to control the appropriate discharge flow rate. It was something that

However, according to the above-mentioned conventional variable displacement pump, the cam ring is held in the pump housing so as to be linearly movable, and the cam ring is provided above or downstream of the variable metering orifice provided directly or indirectly in the discharge passage. Since it is only moved by the differential pressure on the side, it is a problem in terms of workability, operational reliability, and durability, and is not very feasible.

Further, in Japanese Patent Laid-Open No. 58-93978 and Japanese Utility Model Publication No. 63-14078, a cam ring is arranged in a pump housing so as to be linearly displaceable in the radial direction, and a pump chamber is provided in the cam ring. The rotor for forming is rotatably accommodated, and the cam ring is moved and displaced with respect to the rotor by the pressure difference on the downstream side above the variable metering orifice provided in the pump discharge passage,
There is disclosed a variable displacement pump capable of obtaining a desired flow rate by varying the flow area of the variable metering orifice in response to the eccentricity of the cam ring with respect to the rotor and varying the discharge flow rate.

[0010]

However, in such a conventional structure, when the pump discharge pressure is high and the pump housing is distorted, or when dust or the like is mixed in the hydraulic oil that is the pressure fluid, the cam ring is formed. However, there is a problem in that the operating performance is likely to become unstable because it cannot be moved and displaced in a required state.

That is, as is well known, the above-mentioned cam ring has only a small gap in the side surface in order to prevent internal leakage, and clogging of such a gap with dust or the like and contact resistance at the side surface. Due to the increase, there is a possibility that a smooth movement displacement of the cam ring cannot be obtained and a desired adjusted flow rate cannot be obtained.

Further, in order to overcome the above-mentioned adverse effects due to clogging of dust or the like and increase in contact resistance, if the variable metering orifice is formed so that the pressure difference on the upstream side and the downstream side becomes large, a variable displacement pump is obtained. This means that the original purpose of the low power consumption type power steering apparatus will be lost, and it is necessary to take some measures capable of solving these problems.

The present invention has been made in view of the above circumstances. For example, in a vane type oil pump, a cam ring is provided so that a discharge flow rate per one rotation can be changed in accordance with a change in the pump rotation speed. It is an object of the present invention to obtain a variable displacement pump having a simple structure that can be configured to move and displace reliably in a required state and that has excellent operational reliability.

[0014]

In order to meet such a demand, a variable displacement pump according to the present invention (the invention according to claim 1) forms a pump chamber between the rotor and a rotor and at the same time, in a pump body. A cam ring, which is arranged so as to be movable and displaceable, forms a first fluid pressure chamber on one side in the movement direction and a second fluid pressure chamber on the other side in an annular gap space between the pump body and this pump body, and this cam ring. A biasing unit that biases the pump chamber in a direction in which the pump capacity is maximized, a variable metering orifice provided in the pump body in the middle of a pump discharge side passage, and on the variable metering orifice,
A switching valve for controlling the fluid pressure of the first and second fluid pressure chambers by being actuated by the pressure difference on the downstream side is provided, and the first fluid pressure chamber has a fluid on the upstream side of the variable metering orifice. Pressure and the pump suction side fluid pressure are selectively introduced, and the fluid pressure downstream of the variable metering orifice and the pump suction side fluid pressure are selectively introduced into the second fluid pressure chamber. It is characterized by being configured.

The variable displacement pump according to the present invention (the invention according to claim 2) is the variable displacement pump according to claim 1, which is an annular clearance space between the cam ring and the cam ring inside the pump body in the moving direction of the cam ring. A third fluid pressure chamber is provided separately from the second fluid pressure chamber by interposing a sealing means on the other side, and a fluid pressure on the downstream side of the variable metering orifice is provided in the third fluid pressure chamber. With the introduction
The third fluid pressure chamber is connected to one chamber of the switching valve.

[0016]

According to the present invention (the invention according to claim 1), when the pump is started, the cam ring is located on the one side in the moving direction in the pump body and the pump capacity in the pump chamber between the cam ring and the rotor is maximized. Is in a state of being urged by the urging means. At this time, the first fluid pressure chamber is on the pump suction side,
The second fluid pressure chamber is connected to the downstream side of the variable metering orifice on the pump discharge side.

When the pump is driven so as to gradually increase its rotational speed, the switching valve is operated by the pressure difference between the fluid pressure upstream and the fluid pressure downstream of the variable metering orifice on the pump discharge side. Is activated. By the operation of this switching valve, the fluid pressure on the upstream side of the variable metering orifice is introduced into the first fluid pressure chamber on one side of the cam ring, and the fluid pressure on the pump suction side is introduced into the second fluid pressure chamber. be introduced.

The cam ring is attached by the differential pressure between the fluid pressure on the upstream side of the variable metering orifice introduced into the first fluid pressure chamber and the fluid pressure on the pump suction side introduced into the second fluid pressure chamber. It is moved and displaced in the direction of reducing the pump capacity of the pump chamber against the urging force of the urging means. Due to such displacement of the cam ring, the flow rate of the fluid pressure discharged from the pump chamber is reduced.

On the contrary, the rotational speed of the pump decreases and the fluid pressure on the pump suction side is introduced into the first fluid pressure chamber and the fluid pressure on the downstream side of the variable metering orifice is introduced into the second fluid pressure chamber. Then, due to the differential pressure and the biasing force of the biasing means, the cam ring is moved and displaced in the direction of increasing the pump capacity of the pump chamber. Due to such movement displacement of the cam ring, the flow rate of the fluid pressure discharged from the pump chamber increases.

Further, by configuring the variable metering orifice described above so as to change the opening area according to the movement of the cam ring, for example, the fluid pressure on the pump discharge side can be changed to a predetermined flow rate according to the change in the pump capacity of the pump chamber. Can be controlled.

Further, according to the present invention (the invention according to claim 2), the third fluid pressure chamber which is provided on the other side of the cam ring and which is partitioned by the sealing means from the second fluid pressure chamber is variable. The fluid pressure is downstream of the metering orifice.
Therefore, when the first fluid pressure chamber has a pump suction side fluid pressure and the second fluid pressure chamber has a fluid pressure downstream of the variable metering orifice on the pump discharge side, the cam ring has a first fluid pressure chamber. Moves and shifts to the side. Further, when the first fluid pressure chamber has a fluid pressure on the upstream side of the variable metering orifice and the second fluid pressure chamber has a fluid pressure on the pump suction side, the cam ring moves to the second and third fluid pressure chamber sides. Move and displace.

[0022]

1 to 5 show an embodiment of a variable displacement pump according to the present invention. In these drawings, in this embodiment, a vane type oil pump serving as a hydraulic pressure generation source of a power steering apparatus is shown. Will be described.

A vane type variable displacement pump, generally designated by the numeral 10, is as shown in FIGS.
It has a front body 11 and a rear body 12 that form a pump body. The front body 11 is substantially cup-shaped as a whole, and a pump component 13 is provided inside the front body 11.
A storage space 14 for storing and arranging the rear body 12 is formed, and the rear body 12 is combined and integrated so as to close the open end of the storage space 14. The front body 11 has bearings 16a, 1 with a drive shaft 16 for rotatably driving the rotor 15, which is the rotor of the pump component 13, driven from the outside.
It is rotatably supported by 6b and 16c (16b is arranged on the rear body 12 side and 16c is arranged on the pressure plate 20 side described later).

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 a vane 15a. A pump chamber 18 is formed between the inner cam surface 17a and the rotor 15. There is. This cam ring 1
As will be described later, 7 is arranged so as to be movable and displaceable within an adapter ring 19 provided in a fitted state on the inner wall portion of the storage space 14 so as to change the volume of the pump chamber 18. The adapter ring 19 holds the cam ring 17 in the housing space 14 of the body 11 so that the cam ring 17 can move and displace, and the fluid passage 1 described later is formed between the adapter ring 19 and the body inner wall.
It is for forming 9a.

Reference numeral 20 is a pressure plate, and the pressure plate 20 is the rotor 15 and the cam ring 1 described above.
7 and the adapter ring 19 are laminated in pressure contact with the front body 11 side of the pump cartridge. The end surface of the rear body 12 is pressed against the opposite side surface of the pump cartridge as a side plate, and the bodies 11 and 12 are integrally assembled into a desired assembled state. The pump constituent element 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 will be described later) that also functions as a positioning pin and an appropriate detent means (not shown). It is integrally assembled and fixed while being positioned in the rotational direction.

Reference numeral 23 denotes a pump discharge side pressure chamber formed on the bottom side of the storage space 14 of the front body 11 so that the pump discharge side pressure is applied to the pressure plate 20. Reference numeral 24 denotes a pump discharge side passage which is formed in a pressure plate 20 which guides 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 the pump suction side fluid from a suction port 26 (detailed illustration is omitted) provided in a part of the rear body 12 to the pump chamber 18. In the aisle, this aisle 25
Is a pump suction opening 2 that opens at the end surface of the rear body 12.
It is connected to the pump chamber 18 via 5a.

28 is a discharge port, and this discharge port 28
Is the pump chamber 18 to the pump discharge passage 24, the pump discharge pressure chamber 23, and the pressure plate 20.
At a portion for feeding the pump discharge side fluid pressure sent through the fluid passage 20a and the small diameter hole portion 29 drilled at different positions to a hydraulic device such as a power steering device (not shown in the figure). is there. This discharge port 28 is
The front side of the front body 11 is provided with a variable metering orifice 40 formed at a connecting portion to the storage space 14.

Reference numeral 30 denotes a switching valve, which is disposed substantially orthogonal to the side of the storage space 14 in the front body 11 and is used to move and displace the above-mentioned cam ring 17 with respect to the rotor 15. The control is performed by a variable metering orifice 40 which will be described later. This switching valve 30
The body 32 is provided with a spool 32 which is slidably operated by a fluid pressure difference and a biasing force of a spring 31 in a valve hole 30a formed from the side.

In this switching valve 30, one chamber (the left chamber in FIG. 1) 32a of the spool 32 is upstream of a variable metering orifice 40, which will be described later, from the pressure chamber 23 on the pump discharge side through a fluid passage 23a. Side fluid pressure is introduced. Reference numeral 33 in the figure is a plug for closing the valve hole 30a, which has 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 opening 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 the fluid pressure downstream of the variable metering orifice 40 described above reaches the discharge port 28. Body 1 from the middle of the passage
1. Fluid passage 19 formed between adapter ring 19
a, it is guided through the fluid passage 34 formed in the body 11.

Further, in the 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 sides in the axial direction of the valve hole 30a.
Fluid passages 35 and 36 (passage hole 3 of the adapter ring 19) from chambers (first and second fluid pressure chambers 43 and 44 described later) divided into a plurality of annular gap spaces formed between
5a and 36a are included). These passages 3
5, 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.

In the vane type variable displacement pump 10 described above, most of its construction is well known in the prior art, and its detailed description is omitted.

According to the present invention, in the variable displacement pump 10 having the above-described structure, the cam ring 17 which is arranged in the bodies 11 and 12 so as to be movable and displaceable and which forms the pump chamber 18 with the outer peripheral portion of the rotor 15. Cylindrical pressing member 41
A coil spring 42 that is a means for urging the pump chamber 18 so that the pump capacity (volume) of the pump chamber 18 is maximized, and a variable meter provided in the middle of the pump discharge side passage (24, 23, 20a, 29, 28). On the variable metering orifice 40, which is divided and formed by the sealing means (21, 47) interposed at a predetermined position of the annular gap space between the ring orifice 40 and the outer periphery of the cam ring 17 and the body 11 (adapter ring 19). , The first and second fluid pressure chambers 43 and 44 that move and displace 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, and the first and second fluid pressure chambers 43 and 44. 2 fluid pressure chambers 43, 44
On the other hand, above the variable metering orifice 40, there is provided a control switching valve 30 for selectively switching and introducing the fluid pressure on the downstream side and the fluid pressure on the pump suction side.

The switching valve 30 described above selectively introduces the fluid pressure on the upstream side of the variable metering orifice 40 or the fluid pressure on the pump suction side on the pump discharge side with respect to the first fluid pressure chamber 43, and The fluid pressure in each fluid pressure chamber 43, 44 can be controlled by selectively introducing the fluid pressure on the pump suction side or the fluid pressure on the downstream side of the variable metering orifice 40 to the second fluid pressure chamber 44. To do.

Here, in this embodiment, in order to divide the annular gap space between the cam ring 17 and the adapter ring 19 described above, as is apparent from FIG. 1, the annular gap space is left on both sides in the moving direction. , To split right,
The first seal pin 21 positioned below and also functioning as the above-mentioned positioning pin, and the second seal pin 47 installed via a resin sheet in the groove formed in the sliding contact surface of the cam ring 17. Is provided. A space on one side (the 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 4
3 through the fluid passages 35a, 35
At 0, the upstream side of the variable metering orifice 40 is connected to the left chamber 32a or the chamber formed in the approximate center of the spool 32 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 provided on the outer periphery of the cam ring 17 at a position above the variable metering orifice 40 portion reaching the discharge port 28. The second fluid pressure chamber 44 is located in the upper right space of the drawing and is connected to the pump suction side of the switching valve 30 via the fluid passages 36a and 36. Or the right side chamber 32b to which the downstream side of the variable metering orifice 40 is connected.

Further, a space at the lower right in the figure, which is partitioned by the third seal pin 48, is formed as a third fluid pressure chamber 45, and in the third fluid pressure chamber 45, a variable passage in the pump discharge side passage is formed. The fluid pressure on the downstream side of the metering orifice 40 is guided. Then, the third fluid pressure chamber 4
5 is a passage 1 formed outside the adapter ring 19.
9a, the right chamber 32 of the switching valve 30 via the passage 34
connected to b.

Therefore, the switching valve 30 operates according to the fluid pressure difference on the upstream side and the upstream side of the variable metering orifice 40 guided to the left and right chambers 32a and 32b. Then, by controlling the fluid pressures of the first and second fluid pressure chambers 43 and 44 in accordance with the operation of the switching valve 30 as described above, the cam ring 17 can be moved and displaced in a desired state.

In this embodiment, in the above-mentioned annular gap space, on the other side (upper right in the figure) in the moving direction of the cam ring 17 and in the lower right part in the figure except for the second fluid pressure chamber 44, First seal pin 21 and third seal pin 48
And form a third fluid pressure chamber 45.

Further, in this embodiment, the variable metering orifice 40 is bored in the pressure plate 20 which is a side wall portion arranged on the side surface of the cam ring 17, and the fluid pressure passages 23, 20a on the pump discharge side are formed. And a hole portion 29 connecting the third fluid pressure chamber 45 in the annular gap space with each other.
And a cam ring 17 for changing the opening area of the opening end
And the side surface of the.

Here, the above-mentioned third seal pin 48 is used.
As is clear from the relationship between FIG. 1 and FIG. 3, the upper and lower chambers 44, irrespective of the amount of displacement of the cam ring 17,
It is configured to be held with a biasing force and a guide amount in a direction capable of appropriately partitioning 45, and for example, fluid pressure or the like may be used as the above-mentioned biasing force. However, the present invention is not limited to this, and 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 and the sealing property at that portion can be secured.

On the other hand, the pressing member 41 having the above-mentioned cylindrical shape.
As is clear from FIGS. 1, 2 and 4, the guide hole 19 is formed in a part of the outer peripheral portion of the adapter ring 19.
In FIG. 1, the cam ring 17 is arranged so as to be able to move back and forth in the centripetal direction with respect to the cam ring 17 and is interposed between the discharge port 28 and the cam ring 17 so that the pump capacity of the pump chamber 18 becomes maximum, that is, in FIG. It is configured to always push to the left. As such a pressing member 41, the cam ring 17 is pressed and the fluid flow to the discharge port 28 and the variable metering orifice 40 are used.
Any shape may be used as long as it does not interfere with the hole 29 that constitutes the.

According to the above structure, when the pump 10 is started, the cam ring 17 has a pump capacity in the pump chamber 18 between the cam ring 17 and the rotor 15 on one side in the storage space 14 of the body 11. Coil spring 4 to maximize
2. It is in a state of being urged by the pressing member 41. At this time, as apparent from FIG. 1, the switching valve 30 has the first fluid pressure chamber 43 on the pump suction side and the second fluid pressure chamber 4 on the suction side.
4 is connected to the downstream side of the variable metering orifice 40 on the pump discharge side. At this time, the fluid pressure downstream of the variable metering orifice 40 is introduced into the third fluid pressure chamber 45, and this fluid pressure is also higher than the fluid pressure in the first fluid pressure chamber 43. The cam ring 17 is moved and displaced toward the first fluid pressure chamber 43 side as described above.

When the pump rotational 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 a differential pressure with the fluid pressure on the downstream side, and the switching valve 30 operates. The spool 32 is switched and operated, thereby introducing the fluid pressure on the upstream side of the orifice 40 into the first fluid pressure chamber 43 on one side in the moving direction of the cam ring 17 and the second fluid pressure chamber 44 on the other side. To the pump suction side, so that the cam ring 17 is
The displacement of the pump chamber 18 in the direction of decreasing the pump capacity of the pump chamber 18 (right side in FIGS. 1 and 3) is displaced against the urging force of (1).

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 as described above, and this fluid pressure is the above-mentioned first fluid pressure.
The pressure is lower than the fluid pressure on the upstream side of the variable metering orifice 40 introduced into the fluid pressure chamber 43. Therefore, the cam ring 17 is connected to the first fluid pressure chamber 43,
Due to the difference in fluid pressure between the second fluid pressure chamber 44 and the third fluid pressure chamber 45, the second fluid pressure chamber 44 and the third fluid pressure chamber 44, 45 are moved and displaced.

When the switching valve 30 operates as described above, the second fluid pressure chamber 44, which is located on the opposite side of the first fluid pressure chamber 43, is connected to the pump suction side. By the pressure difference with the fluid pressure on the upstream side of the variable metering orifice 40 introduced into the first fluid pressure chamber 43,
The cam ring 17 is moved and displaced in a required state. As a result, the opening / closing amount of the side surface of the cam ring 17 with respect to the opening end of the hole 29 is changed as shown in FIG. 5, and the opening area of the variable metering orifice 40 is changed.
It is possible to obtain a stable movement displacement of the cam ring 17 and obtain a predetermined flow rate to reach the power steering apparatus PS.

Particularly, according to the above-mentioned structure, the switching valve 30 is operated by the differential pressure generated in the variable metering orifice 40 due to the pump discharge amount which increases and decreases with the pump rotation speed.
Is operated to move and displace the cam ring 17 against the biasing force of the coil spring 42 or in response to this biasing force. As a result, the pump capacity of the pump chamber 18 is variably controlled, As shown in FIG. 5, for example, the discharge amount from can be balanced according to the number of rotations of the pump and controlled to obtain desired characteristics.

That is, the variable metering orifice 4
Due to the opening area that changes when the cam ring 17 closes the hole 29 that forms 0, as shown in FIG. 5, the hole 29 is set up so that a predetermined flow rate is obtained when the rotation speed is small, and is larger than a certain value. It is preferable that the flow rate is reduced when it reaches a predetermined value, and that the flow rate is about half of the initial flow rate at a predetermined number of revolutions or more. Here, such discharge amount control is obtained by the variable metering orifice 40 including the hole 29 and the cam ring 17 that controls the opening amount, and for example, the hole 29.
The characteristics can be changed by arbitrarily changing the shape of or by adjusting the opening control amount of the opening area by the cam ring 17.

According to the present invention having the above-described structure, the displacement of the cam ring 17 whose flow rate is controlled by the variable metering orifice 40 as described above due to the swing around the seal pin 21 is one of the moving directions of the cam ring 17. While guiding the fluid pressure on the upstream side of the variable metering orifice 40 to the first fluid pressure chamber 43 formed on the side,
This is done by guiding the fluid pressure on the pump suction side to the second fluid pressure chamber 44 formed on the other side in the moving direction. Since the fluid pressure difference between these chambers 43, 44 is large, the cam ring 17 is easy to move. Become. In the structure described above, the fluid pressure on the downstream side of the variable metering orifice 40 is stored in the third fluid pressure chamber 45, which is located on the other side of the cam ring 17 in the moving direction, together with the second fluid pressure chamber 44. Since it is guided, the cam ring 17 also moves in the above-mentioned 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 distorted or deformed, or dust or the like is mixed in the fluid and the cam ring 17 is placed at a position where the movement of the cam ring 17 is hindered. The force for moving the cam ring 17 can be obtained by the pressure difference between the pump discharge pressure and the pump suction pressure that is sufficiently small.
It is possible to move and displace with a strong force. In this case, a predetermined flow rate can be stably obtained, and the differential pressure on the upstream side and downstream side of the variable metering orifice 40 may be small, so that power consumption can be saved.

The present invention is not limited to the structure of the embodiment described above, and the shape, structure, etc. of each part can be appropriately modified or changed. For example, the cam ring 17 constituting the variable metering orifice 40 opens the opening. It goes without saying that various modifications may be adopted for the shape of the hole 29 whose area is variable, the structure of the switching valve 30, the seal pins 21, 47, 48 and the like. Further, in the above-mentioned embodiment,
The case where the hole portion 29 that changes the opening area on the side surface portion of the cam ring 17 that constitutes the variable metering orifice 40 is bored in the pressure plate 20 arranged on the side surface portion of the cam ring 17 has been illustrated, but the invention is not limited to this. Alternatively, it may be a body facing the side surface of the cam ring 17, or a hole formed in the side wall formed by another plate or the like.

Further, the vane type variable displacement pump 10 having the above-mentioned structure is not limited to the structure of the above-mentioned embodiment, and of course, various devices other than the power steering device described in the above-mentioned embodiment, It goes without saying that it may be applied to a device.

[0054]

As described above, according to the variable displacement pump of the present invention, the force for moving the cam ring is obtained by the pressure difference between the pump suction pressure and the pump suction pressure, which is sufficiently smaller than the pump discharge pressure. It is possible to move and displace the cam ring with a strong force. Further, according to such a variable displacement pump, the pump discharge flow rate is made variable in accordance with the change in the pump rotation speed, the cam ring can be easily and appropriately moved and displaced in a required state, and the flow rate adjustment The discharge flow rate according to the pump rotation speed can be stably obtained by the fluid pressure difference on the upstream side and the downstream side of the variable metering orifice.

Further, according to the present invention, the switching valve can be operated with the fluid pressure difference on the upstream side and the downstream side of the variable metering orifice kept small, and the fluid pressure difference due to this variable metering orifice is small. The cam ring can be moved and displaced in a desired state. Therefore, the power consumption of the pump can be saved.

[Brief description of drawings]

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

FIG. 2 is a longitudinal sectional view of an essential part shown in section for explaining the structure of the essential part of FIG.

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

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

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

FIG. 6 is an enlarged view of a main part showing a modified example 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 (rotating shaft), 17 ... Cam ring, 17
a ... 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 portion constituting variable metering orifice, 30 ... Switching valve, 32 ... 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 ... third seal pin.

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-53-130505 (JP, A) JP-A-59-137673 (JP, A) JP-B-63-16595 (JP, B1) US Patent 2823614 (US) , A) German Patent Application Publication 3322549 (DE, A 1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F04C 15/04 321 B62D 5/07 F04C 2/344 331

Claims (2)

(57) [Claims] 1. A first fluid pressure chamber, which forms a pump chamber with a rotor and is movably arranged in a pump body, and is arranged in an annular space between the pump body and one side in a movement direction. A cam ring forming a second fluid pressure chamber on the other side, a biasing means for biasing the cam ring in a direction in which the pump capacity of the pump chamber is maximized, and a pump discharge side passage in the pump body. A variable metering orifice provided on the way, and a switching valve for controlling the fluid pressure of the first and second fluid pressure chambers by being actuated by the pressure difference on the upstream side and the downstream side of the variable metering orifice, A fluid pressure upstream of the variable metering orifice and a pump suction side fluid pressure are selectively introduced into the first fluid pressure chamber, and a variable metering orifice of the variable metering orifice is introduced into the second fluid pressure chamber. Variable displacement pump, characterized in that the fluid pressure and the pump suction fluid pressure flow side is configured to be selectively introduced. 2. The variable displacement pump according to claim 1, wherein a seal means is provided inside the pump body in the annular gap space between the cam ring and the cam ring, the other side being in the moving direction of the cam ring. A third fluid pressure chamber is provided separately from the second fluid pressure chamber, and the fluid pressure on the downstream side of the variable metering orifice is introduced into the third fluid pressure chamber, and the third fluid pressure chamber is also provided. And a one chamber of the switching valve, which is connected to the variable displacement pump.