JP3501990B2 - 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 system 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.

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

[0011]

However, in such a conventional structure, the structure of the part that constitutes 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 high. It is difficult and causes problems in processing and assembling.

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

The present invention has been made in view of the above circumstances. For example, in a vane type oil pump, a cam ring is moved in order to change the discharge flow rate per one rotation in response to a change in the pump rotational speed. A variable metering orifice that obtains a pressure difference that operates a switching valve that controls the fluid pressures in the first and second fluid pressure chambers to be displaced is constructed with a simple structure, and is linked to the change in the pump capacity of the pump chamber. The purpose of the present invention is to obtain a variable displacement pump that can reliably change the opening area of the variable metering orifice and has high reliability in operation.

[0014]

In order to meet such an object, the variable displacement pump according to the present invention has a pump chamber formed between it and a rotor, and is movably arranged in a pump body. A cam ring that forms a first fluid pressure chamber on one side in the direction of movement with the body and a second fluid pressure chamber on the other side, and this cam ring is urged in a direction that maximizes the pump capacity of the pump chamber. A variable displacement pump having a urging means for activating the variable metering orifice and a variable metering orifice provided in the pump body in the middle of the pump discharge side passage, the variable metering orifice being movable and displaceable in the pump body. A hole formed in the side wall of the arranged cam ring to connect the pump discharge side and the annular gap space between the cam ring and the rotor, and an opening at the opening end of this hole. And a side surface of the cam ring that changes the product according to the movement of the cam ring, and operates by the pressure difference between the upper side and the lower side of the variable metering orifice to change the fluid pressure in the first and second fluid pressure chambers. It is characterized by having a switching valve for controlling.
A variable displacement pump according to a second aspect of the present invention is the variable displacement pump according to the first aspect of the invention, wherein the switching valve has a fluid upstream of the variable metering orifice in the first fluid pressure chamber. Pressure and the fluid pressure on the suction side of the pump are selectively introduced, and the fluid pressure on the downstream side of the variable metering orifice and the fluid pressure on the suction side of the pump are selectively introduced into the second fluid pressure chamber. It is configured in.
A variable displacement pump according to a third aspect of the present invention is the variable displacement pump according to the first or second aspect of the present invention, which is an annular gap space between the inside of the pump body and the cam ring, and is a 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 in the moving direction of the, and a hole portion of the variable metering orifice is opened in the third fluid pressure chamber. By doing so, the fluid pressure on the downstream side of the variable metering orifice is introduced.

According to the present invention, the cam ring has the first and second cam rings.
By moving and displacing in the pump body by 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 cam ring on the side wall of the pump body changes. Function as a variable metering orifice.

[0016]

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

A vane type variable displacement pump, generally designated by reference 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 this 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 pressure discharge 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. The switching valve 30 is arranged substantially orthogonal 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 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 the switching valve 30, one chamber (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 art, and its detailed description is omitted.

Variable displacement pump 10 having the above-mentioned configuration
At the pump capacity (volume) of the pump chamber 18 via the cylindrical pressing member 41, the cam ring 17 that is movably arranged in the bodies 11 and 12 and forms the pump chamber 18 with the outer peripheral portion of the rotor 15 is disposed. Coil spring 42, which is a means for urging the pump discharge side passage (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 midway and the body 11 (adapter ring 19) on the outer peripheral portion of the cam ring 17. Firstly, the cam ring 17 is moved and displaced by selectively introducing the fluid pressure on the downstream side or the fluid pressure in the pump suction side passage 27 on the variable metering orifice 40 dividedly formed by (21, 47). The second fluid pressure chambers 43 and 44, and the fluid pressure on the downstream side and the fluid pressure on the pump suction side selectively above the variable metering orifice 40 with respect to the first and second fluid pressure chambers 43 and 44. And a control switching valve 30 for switching and introducing.

In this embodiment, the switching valve 30 described above selectively selects 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. Of the fluid pressure chambers 43 and 44 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. 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 described above, as is apparent from FIG. 1, the annular gap space is left on both sides in the moving direction. , The first seal pin 21 which functions as the above-mentioned positioning pin positioned to be positioned above and below so as to be divided into the right part and the groove formed in the groove formed in the sliding contact surface of the cam ring 17 with the resin sheet interposed therebetween. A second seal pin 47 incorporated therein is provided. A space on one side (left side in the figure) of the moving direction of the cam ring 17 is used 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, 35. The left chamber 32a or the spool 32 to which the upstream side of the metering orifice 40 is connected
It is configured so that it can be connected to a chamber that is formed substantially in the center and is 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, a 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 in the drawing and is connected to the pump suction side of the switching valve 30 via the fluid passages 36a and 36. Right chamber 32 to which the downstream side of the variable chamber or variable metering orifice 40 is connected
It is configured to be connectable to b.

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

The fluid pressure on the downstream side of the variable metering orifice 40 in the pump discharge side passage is introduced into the third fluid pressure chamber 45. That is, since the hole portion 29 forming the variable metering orifice 40 is opened in the third fluid pressure chamber 45, the fluid pressure in the chamber 45 becomes the fluid pressure on the downstream side of the variable metering orifice 40. There is. Further, the third fluid pressure chamber 45 is
A passage 19a formed outside the adapter ring 19,
It is connected to the right chamber 32b of the switching valve 30 via a passage 34.

According to the present invention, the variable metering orifice 40 is bored in the pressure plate 20, which is the side wall portion arranged on the side surface of the cam ring 17, so as to form the third side of the pump discharge side and the annular gap space. The hole 29 connecting the fluid pressure chamber 45 and the side surface of the cam ring 17 for changing the opening area of the opening end of the hole 29. And
The cam ring 17 serves as the first and second fluid pressure chambers 43, 44.
When the cam ring 17 moves due to the fluid pressure difference in the inside, the side surface of the cam ring 17 closes the hole 29 in proportion to the displacement amount
The opening area can be reduced or expanded, and the function as the variable metering orifice 40 can be exhibited.

Here, the third seal pin 48 described above 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. 1B, the cam ring 17 is arranged so as to be movable back and forth in the centripetal direction with respect to the cam ring 17, and is interposed by the coil spring 42 between the cam ring 17 and the discharge port 28. It is configured to always press the center left. Such a pressing member 41
As the pressure of the cam ring 17, the fluid flow to the discharge port 28 and the variable metering orifice 4
If the shape does not interfere with the hole 29 that constitutes 0,
It may have any shape.

According to the above-described 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 of the housing space 14 of the body 11, as is apparent from FIG. 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 on the downstream side of the variable metering orifice 40 is introduced into the third fluid pressure chamber 45 by the hole portion 29 which constitutes the variable metering orifice 40 and has the largest opening area. Since the fluid pressure is also higher than the fluid pressure in the first fluid pressure chamber 43, the cam ring 17 is provided in the first fluid pressure chamber 4 as described above.
It is moved and displaced to the 3 side.

When the pump rotational speed is gradually increased and 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 is driven. The spool 32 is operated, whereby the first fluid pressure chamber 4 on one side in the moving direction of the cam ring 17 is activated.
3, the fluid pressure on the upstream side of the orifice 40 is introduced, and the second fluid pressure chamber 44 on the other side is connected to the pump suction side. As a result, the cam ring 17 resists the biasing force of the coil spring 42. The pump chamber 18 is moved and displaced in the direction in which the pump capacity decreases (right side in FIGS. 1 and 3).

At this time, in the third fluid pressure chamber 45, the variable meter ring passing through the hole portion 29 whose opening area is reduced by being directly blocked by the side surface portion due to the displacement of the cam ring 17 The fluid pressure on the downstream side 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 causes the fluid pressure difference between the first fluid pressure chamber 43 and the second and third fluid pressure chambers 44, 45 as described above. Is moved and 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, 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.

In particular, 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 or 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 performed by the hole 2
9 and the variable metering orifice 40 by the 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 control amount of the opening area by the cam ring 17. Moreover, the above-mentioned cam ring 17 is a member that follows the pump capacity of the pump chamber 18, and the hole 29 is formed in the side surface of the cam ring 17.
Since the opening area of the variable metering orifice 40 is directly changed, the operational reliability of the variable metering orifice 40 is excellent.

Variable displacement pump 10 having the structure described above.
According to the above, the displacement caused by the swing of the cam ring 17 whose flow rate is controlled by the variable metering orifice 40 as described above about the seal pin 21 is the first fluid pressure formed on one side in the moving direction of the cam ring 17. Chamber 43
The fluid pressure on the upstream side of the variable metering orifice 40 is introduced to the second fluid pressure chamber 44, and the fluid pressure on the pump suction side is introduced to the second fluid pressure chamber 44 formed on the other side in the moving direction. , 44 has a large fluid pressure difference, the cam ring 17 can easily move. In the structure described above, the third fluid pressure chamber 45, which is located together with the second fluid pressure chamber 44 on the other side in the moving direction of the cam ring 17, includes:
Since the fluid pressure on the downstream side of the variable metering orifice 40 is introduced, 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 and 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 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 in the above-described embodiment, and the shape, structure, etc. of each part of the variable displacement pump 10 can be freely modified and changed, and various kinds can be freely changed. It goes without saying that a modified example may be adopted.
Further, in the above-described embodiment, the hole 29 that changes the opening area on the side surface of the cam ring 17 that constitutes the variable metering orifice 40 is formed in the pressure plate 20 arranged on the side surface of the cam ring 17. Although illustrated, the present invention is not limited to this, and may be a hole facing the side surface of the cam ring 17 or other side wall formed by a plate or the like.

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

[0049]

As described above, in the variable displacement pump according to the present invention, since the variable metering orifice is constituted by the hole portion whose opening area is directly changed by the movement of the cam ring, the number of extra parts is increased. It is possible to configure with a minimum number of constituent parts without needing, and 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 of the pump rotation speed, the cam ring can be easily and appropriately moved and displaced in a required state, and the cam ring which is displaced and moved can be used. It is possible to obtain a desired discharge flow rate according to the number of rotations of the pump by increasing or decreasing the opening area of the hole forming the variable metering orifice for flow rate adjustment to a desired state. Therefore, it is also excellent in reliability in operation as a variable metering orifice.

[Brief description of drawings]

FIG. 1 is a schematic transverse 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 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, 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 portion constituting 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 ... Third seal pin.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-4-17792 (JP, A) JP-A-58-93978 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F04C 15/04 B62D 5/07 F04C 2/344 331

Claims (3)

(57) [Claims] 1. A first fluid pressure chamber is formed between the rotor and a rotor so as to be movable and displaceable within the pump body, and a first fluid pressure chamber is provided between the rotor and the pump body on one side in the 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 in the middle thereof. A variable displacement pump provided with a variable metering orifice provided, wherein the variable metering orifice is drilled in a side wall portion arranged on a side surface portion of a cam ring movably arranged in the pump body. A discharge hole, a cam ring, and a hole portion that connects the annular gap space between the rotor, and a cam ring side surface portion that changes the opening area of the opening end of the hole portion according to the movement of the cam ring,
A variable displacement pump comprising a switching valve that operates by a pressure difference between the upper side and the lower side of the variable metering orifice to control the fluid pressure in the first and second fluid pressure chambers. 2. The variable displacement pump according to claim 1, wherein the switching valve selectively introduces a fluid pressure upstream of the variable metering orifice and a fluid pressure suction side of the pump into the first fluid pressure chamber. A variable displacement pump characterized in that the fluid pressure on the downstream side of the variable metering orifice and the fluid pressure on the pump suction side are selectively introduced into the second fluid pressure chamber. 3. The variable displacement pump according to claim 1 or 2, wherein a sealing means is provided on the other side of the cam ring in the annular gap space between the inside of the pump body and the cam ring. A third fluid pressure chamber is provided separately from the second fluid pressure chamber, and in the third fluid pressure chamber,
A variable displacement pump characterized in that a fluid pressure on the downstream side of the variable metering orifice is introduced by opening a hole of the variable metering orifice.