JP2001159395A - Variable displacement pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure required pump discharge by constituting a variable displacement pump for a power steering to cope with the conditions of vehicle speed, a steering angle, and the like. SOLUTION: A cam ring 17 for forming a pump chamber 18 between a rotor 15 and the cam ring 17 in a pump body 11 is provided and energized in a direction of maximizing pump displacement. First and second fluid pressure chambers 33, 34 are formed between the pump body 11 and both moving direction sides of the cam ring 17, being partitioned from pump discharge side passages 27, 51. The cam ring 17 is displaced in the direction of increasing/decreasing pump displacement by the fluid pressure difference between both chambers 33, 34. The pump discharge side passage 51 is provided with a metering throttle 50, and an electronic control means such as a solenoid 60 and electronic control parts 61, 62 for controlling the driving current are provided for variably controlling the metering throttle 50.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement pump used as a fluid pressure source in a pressure fluid utilizing device such as a power steering device for reducing a steering operation force of an automobile.

[0002]

2. Description of the Related Art Heretofore, as a pump for a power steering device of this type, a displacement vane pump directly driven and rotated by an automobile engine has been used. Since the displacement flow rate of such a displacement pump increases or decreases in response to the engine speed, the power assisted steering increases the steering assist force when the vehicle is stopped or running at low speed, and decreases the steering assist force during high speed running. It must have characteristics that are inconsistent with the steering assist force required for the device.

Therefore, it is necessary to use a large-capacity displacement pump capable of securing a discharge flow rate such that a necessary steering assist force can be obtained even at a low speed running at a low rotation speed. In addition, during high-speed running at a high rotation speed, a flow control valve that controls the discharge flow rate to a certain amount or less is essential. For this reason, the number of components becomes relatively large, the structure and the passage configuration become complicated,
It is inevitable that the overall size and cost will increase.

For this reason, there has been proposed a pump provided with a control means on the discharge side of the pump to recirculate the fluid on the discharge side of the pump to the tank in accordance with running conditions such as vehicle speed. However, even when such a structure is employed, even when the pump is rotating at a high speed, the pump discharge flow is only diverted to the tank, and the flow consumed by the power steering device as the steering assisting force is small. Despite the decrease, the load on the pump drive did not decrease.

In order to solve such a problem, a variable displacement vane pump for reducing the discharge flow rate (cc / rev) per rotation in proportion to an increase in the number of rotations is disclosed in Japanese Patent Laid-Open No. 6-20.
No. 0883, JP-A-7-243385, JP-A-8-200399, and the like.
In these variable displacement pumps, when the engine speed (pump speed) increases, the cam ring moves in the pump body in the direction in which the pump capacity of the pump chamber decreases in accordance with the magnitude of the fluid pressure on the pump discharge side. Therefore, the flow rate on the discharge side from the pump can be reduced. Therefore, the flow control valve attached to the displacement pump becomes unnecessary, and the driving horsepower can be reduced, which is advantageous in energy efficiency.

When this type of variable displacement pump is used as a hydraulic power source for a power steering device, the engine speed is low when the vehicle is stopped or running at low speed, but the discharge from the pump is relatively large. Accordingly, the steering operation can be assisted by a large steering assist force, and light steering can be performed. In addition, when the vehicle travels at a high speed at a high traveling speed, the engine speed increases, and the discharge amount from the pump decreases accordingly, so that steering with appropriate rigidity for steering operation can be obtained.

[0007]

Conventionally, this type of variable displacement pump can provide a discharge amount that can follow the magnitude of the engine speed when used as a hydraulic source for a power steering device. However, since changes in conditions such as vehicle speed, steering angle, and steering speed are not taken into consideration, there are the following problems.

That is, since the conventional variable displacement pump is of a so-called engine speed-sensitive type, the engine speed increases during acceleration, uphill and downhill, even at low speeds. The discharge flow rate is reduced. If the steering operation is performed during such low-speed traveling, there is a possibility that the pump discharge amount is too small to secure a necessary flow rate in the power steering device, and a problem that the steering assist force becomes insufficient. For this reason, in the conventional pump, the flow rate could not be reduced so much to secure the required flow rate.

Therefore, in the conventional variable displacement pump, there is a limit in reducing the discharge flow rate from the pump when the engine speed is increased. And the effect of saving energy was insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is possible to supply a sufficient flow rate when an operation of a pressure fluid utilizing device, for example, a steering assist force is required, and to provide a steering assist force. The purpose of the present invention is to provide a variable displacement pump capable of supplying a minimum necessary flow rate when the pressure fluid is not required, and ensuring the required and sufficient and high reliability of the supply flow rate to the pressure fluid utilization device. And

Another object of the present invention is to provide a variable displacement pump capable of exhibiting the maximum energy saving effect by minimizing the power consumption required for driving the pump.

Further, the present invention is, for example, a vehicle-mounted hydraulic pump, which is used as a hydraulic power source for a power steering device by controlling the vehicle in accordance with running conditions such as a vehicle speed and a steering angle to provide a comfortable vehicle. A variable displacement that can provide a great steering feeling and reduce the discharge flow rate as much as possible when steering operation is not necessary, for example, when the vehicle is running straight, so that the energy saving effect can be further exhibited. The aim is to get a pump.

[0013]

According to a first aspect of the present invention, there is provided a variable displacement pump in which a pump chamber is formed between a pump body and a rotor in a pump body. A cam ring urged in a direction in which the capacity is maximized; and first and second fluid pressure chambers formed between the cam ring and the pump body on both sides in the moving direction of the cam ring. 2. A metering throttle provided in a passage on the pump discharge side in a variable displacement pump which is movable and displaceable in a direction to increase and decrease the pump capacity of the pump chamber by a fluid pressure difference in the fluid pressure chamber. Electronic control means for variably controlling is provided.

According to the present invention (the invention described in claim 1),
By controlling the metering throttle to change the throttle amount by the electronic control means, the fluid pressure in the first and second fluid pressure chambers for moving and displacing the cam ring is controlled in a required state, and the discharge flow rate from the pump is controlled. Can be controlled to a desired value.

According to a second aspect of the present invention, in the variable displacement pump according to the first aspect of the present invention, the first and second fluid pressure chambers are respectively provided at positions separated from the passage on the pump discharge side. It is characterized by the following.

According to the present invention (claim 2), the first and second pumps can be operated even if a load pressure fluctuation occurs in the pump discharge side passage.
Pulsation on the pump discharge side due to vibration of the cam ring can be prevented.

According to a third aspect of the present invention, there is provided a variable displacement pump according to the first aspect, further comprising a control valve for controlling a fluid pressure in the first and second fluid pressure chambers. And

According to the present invention (the invention described in claim 3),
The fluid pressure on the pump suction side can be introduced into at least one of the fluid pressure chambers formed on both sides in the movement direction of the cam ring to obtain the working pressure, so that it is necessary for proper and reliable displacement of the cam ring. A fluid pressure difference can be obtained.

According to a fourth aspect of the present invention, in the variable displacement pump according to the first aspect, the first fluid pressure chamber is provided with a fluid pressure between the upstream side of the metering throttle and the pump suction side.
A control valve is provided for connecting the second fluid pressure chamber to fluid pressure on the pump suction side and fluid pressure on the downstream side of the metering throttle, respectively.

According to the present invention (the invention described in claim 4),
The fluid pressure difference required to move the cam ring can be increased.

According to a fifth aspect of the present invention, in the variable displacement pump according to the fourth aspect, the downstream side of the metering throttle is connected to one chamber of the control valve via a pilot throttle. .

According to the present invention (the invention described in claim 5),
Since the downstream side of the metering throttle and the one chamber of the control valve (low pressure side spring chamber) are connected via the pilot throttle in the pump discharge side passage, the pressure fluctuation in the pump discharge side passage is reduced. The discharge flow rate at the time of relief transmitted directly to the control valve side or at the control valve side can be further reduced.

According to a sixth aspect of the present invention, in the variable displacement pump according to the first aspect, a pilot pressure passage branched from an upstream side of the metering throttle in the pump discharge side passage is provided with the first fluid. A pilot pressure passage branched from a downstream side of the metering throttle and connected to the pressure chamber is connected to the second fluid pressure chamber.

According to the present invention (the invention described in claim 6),
Since the first and second fluid pressure chambers are connected by the pilot pressure passage bypassed from the pump discharge side passage, the influence of fluid pressure fluctuation on the load side does not affect the first and second fluid pressure chambers. .

A variable displacement pump according to a seventh aspect of the present invention is characterized in that, in the first aspect, the metering throttle is constituted by a fixed throttle and a variable throttle.

According to the present invention (the invention described in claim 7),
The degree of freedom of the flow characteristic can be increased.

The variable displacement pump according to the invention of claim 8 is the fluid pressure source of the power steering device according to claim 1, wherein the electronic control means includes at least one of a vehicle speed and a steering angle. The metering aperture is variably controlled by one input.

According to the present invention (the invention described in claim 8),
When running a vehicle, it is necessary to minimize the flow rate during normal straight running without steering operation, and to secure a sufficient flow rate when the steering assist force by the power steering device is required. it can.

[0029]

1 and 2 are views showing one embodiment of a variable displacement pump according to the present invention. In this embodiment, the variable displacement pump according to the present invention
A vane-type oil pump serving as a hydraulic pressure source of a power steering device, wherein a discharge flow rate thereof becomes a predetermined flow rate smaller than a maximum discharge flow rate as the rotation speed of the pump increases, and the flow rate is maintained. A description will be given of a pump having a so-called drooping characteristic.

In FIG. 1 and FIG.
The variable displacement pump of the vane type shown in FIG. 1 includes a front body 11 and a rear body 12 that constitute a pump body. The front body 11 has a substantially cup shape as a whole, and a storage space 14 for storing and arranging a pump component as a pump cartridge is formed therein, and a rear body is formed so as to close an open end of the storage space 14. 12 are assembled and integrally assembled.

A bearing 16a, a drive shaft 16 for externally rotating a rotor 15 constituting a pump component is penetrated through the front body 11.
16b (16a is disposed on the front body 11 side, 16b is disposed on the rear body 12 side) and is rotatably supported. This rotor 15 rotates in the counterclockwise direction shown by the arrow in FIG. 16c is an oil seal.

Reference numeral 17 denotes a cam ring.
Has an inner cam surface 17a fitted and arranged on the outer peripheral portion of the rotor 15 having the vane 15a, and forms a pump chamber 18 between the inner cam surface 17a and the rotor 15. The cam ring 17 is positioned eccentrically with respect to the rotor 15, and a substantially crescent-shaped space formed between the cam ring 17 and the rotor 15 serves as a pump chamber 18. The cam ring 17 is swingably arranged in an adapter ring 19 provided in the storage space 14 so as to be fitted to an inner wall portion of the space so that the volume (pump capacity) of the pump chamber 18 can be varied as described later. Have been. A compression coil spring 17b biases the cam ring 17 in a direction in which the pump capacity of the pump chamber 18 is maximized.

In FIG. 2, reference numeral 20 denotes a pressure plate. The pressure plate 20 is pressed against the front body 11 of a pump cartridge (pump component) constituted by the rotor 15, the cam ring 17 and the adapter ring 19 described above. They are arranged in a stack. 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 front body 11 and the rear body 12 are integrally assembled.

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 integrally assembled while being positioned in the rotational direction by a swing fulcrum pin 21 described later. ing. The swing fulcrum pin 21 functions as a shaft support and a positioning pin for enabling the cam ring 17 to swing, and also functions as a seal material defining a fluid pressure chamber for swinging the cam ring 17.

Numerals 22 and 23 denote a pump suction side opening and a pump discharge side opening which open into the pump chamber 18, and these openings 22 and 23 are formed by substantially arc-shaped grooves, and as shown in FIG. Are opened at the pump suction side area at the start end side and the pump discharge side area at the end side in the rotation direction. As shown in FIG. 2, the suction-side opening 22 is formed in the end face of the rear body 22 facing the pump chamber 18, and the discharge-side opening 23 is formed in the pump chamber 1 of the pressure plate 20.
It is recessed on the end face on the eight side.

The rear body 12 is provided with a suction-side passage 25 through which the suction-side fluid sucked from the tank T is supplied to the suction-side opening 22 through a suction port.
The suction side fluid sucked from the tank T (pump suction side) is supplied from the suction port through the pump suction side passage 25 in the rear body 12 to the pump chamber 18 through the suction side opening 22 opened at the end face of the rear body 12. Is done. 25a
Is a pump suction side passage opening at the center of the valve hole 31.

On the front side of the pressure plate 20 of the front body 11, a substantially arc-shaped pump discharge side pressure chamber 26 is formed around the drive shaft 16. The pressure chamber 26 is connected to a discharge port 27a via a pump discharge passage 27 formed in the front body 11, and is configured to discharge the discharge-side fluid pressure guided to the pressure chamber 26 from the discharge port 27a. ing.

Reference numeral 30 denotes a control valve formed of a valve hole 31 and a spool 32 formed above the front body 11 in a direction perpendicular to the shaft 16, and a metering throttle 50 provided in the middle of a pump discharge side passage described later. upon,
Activated by downstream pressure differential. This control valve 30
As a result, the fluid to be introduced into the first and second fluid pressure chambers 33 and 34 formed separately on both sides of the cam ring 17 in the adapter ring 19 by the swing fulcrum pin 21 and the seal member 35 provided at the axially symmetric position. The pressure is controlled according to the pump speed.

At one end of the valve hole 31, fluid pressure on the pump discharge side is supplied from the pressure chamber 26 to the pilot pressure passage 4.
1 is formed, and a chamber 38 for introducing the fluid pressure P1 upstream of the metering throttle 50 is formed. A spring chamber 36 having a compression coil spring 36a for urging the spool 32 toward the one end side is provided at the other end side of the valve hole 31.
Are formed. The spring 36a urges the spool 32 to the left in FIG.

In the spring chamber 36, a meter is provided in the discharge side passage 51 of the pump, between the discharge port 27a of the pump 10 and a pressure fluid utilization device (here, a power cylinder PS of a power steering device). The fluid pressure P2 on the downstream side of the ring throttle 50 is guided by the pilot pressure passages 42 and 43. The pilot pressure passage 43 is a passage formed in the front body 11, and a pilot throttle 43a is formed in a part thereof.

The pilot throttle 43a is provided in a part of the pilot pressure passages 42 and 43 which are the pump discharge side passage 51 and are branched from the downstream side of the metering throttle 50 and reach the spring chamber 36 of the control valve 30. Can be When such a pilot throttle 43a is provided, the control valve 3
It is possible to prevent adverse effects due to fluid pressure fluctuation on the zero spool 32 and the like.

A relief valve 49 is provided inside the spool 32. When the pilot throttle 43a as described above is provided, the pressure in the spring chamber 36 of the control valve 30 drops when the relief valve 49 is relieved. The supply fluid pressure to the pressure chamber 34 can be reduced. And such a pilot aperture 43
When the relief valve 49 is provided, the cam ring 17 can be swung in the direction in which the volume of the pump chamber 18 decreases when the relief valve 49 is relieved, and the discharge amount from the pump can be further reduced. Can be achieved.

The spring chamber 36 is connected to the second fluid pressure chamber 34 by a connection passage 37 when the spool 32 is at the position shown in FIG.
2 moves to the spring chamber 36 side (to the right in the drawing).
Is configured to be gradually separated from the fluid pressure chamber 34. Therefore, the second fluid pressure chamber 34 has a fluid pressure P2 downstream of the metering throttle 50 and a fluid on the pump suction side through the spring chamber 36 and the pump suction side chamber 30a formed by the annular groove at the center of the spool 32. Pressure is supplied as the spool 32 moves. A damper throttle 37a is formed in a part of the connection passage 37 described above.

The high pressure side chamber 38 formed at one end of the spool 32 is closed when the spool 32 is at the position shown in FIG.
When it moves to the right side (in the figure, right side in the figure), it is configured to be selectively connected to the first fluid pressure chamber 33 via a connection passage 39 which is gradually disconnected from the pump suction side. Therefore, in the first fluid pressure chamber 33, the fluid pressure on the pump suction side and the fluid pressure P1 on the upstream side of the metering throttle 50 through the pump suction side chamber 30a and the high pressure side chamber 38 are spooled. Is supplied along with the movement of.
A damper throttle 39a is formed in a part of the connection passage 39.

In FIG. 1, the connection passage 39 is provided with a pump suction side chamber 30a formed by an annular groove in the axial center portion of the spool 32 through a clearance passage formed by a chamfer formed in a land portion at one end of the spool 32. It is connected to the. Then, depending on the displacement amount of the spool 32,
The fluid pressure P1 on the pilot pressure passage 41 side (the fluid pressure on the upstream side of the metering throttle 50) is selectively connected to the first fluid pressure chamber 33 via the connection passage 39.

When the above-described control valve 30 is used, the fluid pressure chambers 33, 3 formed on both sides in the moving direction of the cam ring 17 despite the low operating pressure of the valve 30.
The fluid pressure on the pump suction side can be introduced into at least one of the four to make the working pressure, but since the fluid pressure difference can be increased, a reliable displacement of the cam ring 17 can be obtained. be able to.

When the pump is started or at a low speed, the differential pressure on the metering throttle 50 and on the downstream side is small.
2 is at the position shown in FIG. 1, the first fluid pressure chamber 33 is connected to the pump suction side, and the fluid pressure P0 is introduced.
On the other hand, the fluid pressure P2 on the pump discharge side downstream of the metering throttle 50 is introduced into the second fluid pressure chamber 34, and the cam ring 17 maintains the state where the volume of the pump chamber 18 is maximized. I do.

When the rotational speed of the pump is in the middle or high speed region and the discharge flow rate from the pump chamber 18 is large, the differential pressure on the metering throttle 50 and on the downstream side increases, and the spool 32 deflects the spring 36a. The chamber 38 to which the pilot pressure passage 41 is connected is connected to the connection passage 39. In this case, the fluid pressure P1 on the upstream side of the metering throttle 50 is introduced into the first fluid pressure chamber 33 with the movement of the spool 32.

On the other hand, in the second fluid pressure chamber 34, the supply of the fluid pressure P2 downstream of the metering throttle 50 to the passage 37 is closed by the land portion with the movement of the spool 32, and the land portion is closed. It is connected to the pump suction side via a gap passage formed by a chamfer formed in the section.
As a result, the second fluid pressure chamber 34 becomes the fluid pressure P0 on the pump suction side, and the cam ring 17 swings to the right in FIG. 1 as described above, and the volume of the pump chamber 18 decreases. In the vane-type variable displacement pump 10 as described above, the configuration other than the above-described configuration is widely known in the related art, and a specific description thereof will be omitted.

According to the present invention, in the variable displacement pump having the above structure, the metering throttle 50 provided in the passage 51 on the pump discharge side, and the metering throttle 50
Are provided with a solenoid 60 as an electronic drive, a CPU 61 constituting an electronic control unit, a solenoid drive circuit 62, a vehicle speed sensor 63, and a steering angle sensor 64.

In FIG. 1, reference numeral 52 denotes a body forming the metering throttle 50, and passage holes 53 and 54 which constitute a part of the pump discharge side passage 51 are provided. 5
Numerals 5 and 56 are small holes connecting the passage holes 53 and 54, one small hole 55 is a fixed throttle, and the other small hole 56 is a portion to be a variable throttle.

Reference numeral 57 denotes a rod which moves forward and backward with respect to the small hole 56 by the solenoid 60, and a gap formed between the tip of the rod 57 and the small hole 56 constitutes a variable throttle. In the figure, reference numeral 58 denotes a passage hole branched from the passage hole 54 on the downstream side of the metering throttle 50 and connected to the pilot pressure passage 42.

According to such a configuration, the electronic control means controls the variable diaphragm (56) of the metering diaphragm 50 to move and displace the cam ring 17 first.
By controlling the fluid pressure in the second fluid pressure chambers 33 and 34 in a required state, the discharge flow rate from the pump 10 can be arbitrarily controlled.

If a steering speed sensor, an axle load sensor, or a sensor capable of detecting various running conditions is used in addition to the sensors 63 and 64 described above, the flow rate can be changed to further match the steering conditions. Although control becomes possible, at least one of the vehicle speed and the steering angle may be used.

Here, the flow characteristics can be arbitrarily set by appropriately adjusting the passage areas of the fixed throttle (55) and the variable throttle (56) which constitute the metering throttle 50 described above.

According to the above-described structure, the flow rate of the pressure fluid supplied from the variable displacement pump 10 to the power steering device is
By performing proportional control in accordance with the running conditions of the vehicle, such as the vehicle speed and the steering angle, together with the engine speed, the steering assist force can be appropriately applied when the steering operation is required regardless of the running state. In addition, since the pump discharge flow rate can be kept to a minimum during non-steering such as straight running, a large energy saving effect can be expected. That is,
By adopting a vehicle speed sensitive type that also uses electronic control, a comfortable steering feeling can be obtained and an energy saving effect can be obtained.

FIG. 3 shows such characteristics. Here, the solid line is an example of the flow rate characteristic at the time of steering when the electronic control according to the present invention is performed, and the supply flow rate from the pump 10 can be set to about 4 l / min. In the conventional variable displacement pump, as shown by a broken line in FIG.
In contrast to the above setting, the power consumption for driving the pump 10 can be reduced, and the energy saving effect is large. The dashed line in the figure indicates the flow rate characteristic when the steering is not performed (when the vehicle is traveling straight) when the electronic control according to the present invention is performed.

Further, the above-described variable displacement pump 10 is
If the control is performed in accordance with the steering speed signal, the pump discharge amount at the time of performing the steering operation can be increased as necessary, and the hydraulic response delay at the time of sudden steering can be prevented.

In the above-described structure, when the supply current to the solenoid 60 is cut off at the time of electronic control failure in which one of the electronic control means has failed, the small hole 56 is opened, and the flow control metering of the pump 10 is performed. The throttle 50 is a fixed-quantity pump that operates according to a pressure difference downstream and upstream of a fixed throttle opening. By doing so, although the energy saving effect is reduced, the same discharge amount as in low-speed running is maintained.

In the above-described embodiment, the first and second fluid pressure chambers 33 and 34 are provided at positions separated from the passage 51 on the pump discharge side. And the pilot pressure passages 41 and 42 and the left and right chambers 38 and 36 of the control valve 30. That is, the first and second fluid pressure chambers 33, 34
Is provided in a position parallel to the pump discharge side passage 51. According to such a structure, the first and second
Since the load pressure fluctuation is not transmitted to the fluid pressure chambers 33 and 34, pulsation can be prevented.

FIG. 4 shows a modification of the variable displacement pump according to the present invention. The first and second fluid pressure chambers 33 and 34 for moving and displacing the cam ring 17 have pilot pressure passages 41 and 4 respectively.
2 shows an example in which fluid pressures on the metering throttle 50 and on the downstream side are directly introduced via the valve 2. According to such a configuration, the fluid pressure difference for moving the cam ring 17 is smaller than that of the above-described embodiment, but the original movement cannot be achieved, and the cost is reduced because the control valve 30 is not provided. Can be achieved. .

The present invention is not limited to the structure described in the above embodiment, and it goes without saying that the shape, structure, etc. of each part can be appropriately modified or changed. For example, in the above-described embodiment, the supply flow rate from the pump is set to 4 l / mi.
The case where the steering force is reduced to about n has been described. However, the present invention is not limited to this. If the steering force is sufficient in consideration of running conditions such as the vehicle speed and the steering angle, the steering force can be reduced to about 2 l / min.

In the above-described embodiment, the CPU 61 and the drive circuit 62 are used as electronic control units for controlling electronic drive means such as the solenoid 60, and the vehicle speed sensor 6 is used.
Although the case where the driving current to the solenoid 60 is controlled by inputting the vehicle speed from the steering wheel 3 and the steering angle from the steering angle sensor 64 to the CPU 61 as input signals has been exemplified,
The present invention is not limited to this, and any configuration may be used as long as the discharge flow rate of the pump can be controlled in accordance with various running conditions of the vehicle including the engine speed, steering speed, axle load, and the like.

The electronic drive means includes, for example, a solenoid 60, but is not limited to this, and a drive device such as an electromagnet device or an electric motor is configured directly or indirectly via mechanical transmission means such as a lever or a cam. Means may be used. One example is disclosed in, for example, Japanese Patent Publication No. 54-4135.

In the above-described embodiment, the variable displacement pump 10 used as a hydraulic source of the power steering device mounted on the vehicle is exemplified. However, the present invention is not limited to this, and the supply flow rate from the pump is required. By increasing or decreasing the pressure in accordance with the above, the reliability in the operation of the pressure fluid utilization device can be ensured, while the pump power can be reduced and any energy saving effect can be exhibited.

In the above-described embodiment, the metering diaphragm 50 is composed of a fixed diaphragm and a variable diaphragm. However, the metering diaphragm 50 may be a variable diaphragm which is not closed so that a fixed amount is opened as a fixed diaphragm.

In the above-described embodiment, the body 52 having the metering diaphragm 50 which characterizes the present invention is used.
In the power steering apparatus, the variable displacement pump 10, the power cylinder and the power steering main body having the control valve are configured independently of the power steering main body, and the pipe connection is illustrated, but the invention is not limited thereto. For example, it may be provided integrally or integrally with the body of the pump 10,
It may be provided integrally or integrally with the power steering body. What is necessary is just to select suitably according to the installation space at the time of mounting in a vehicle, and layout configuration.

[0068]

As described above, according to the variable displacement pump according to the present invention, an arbitrary pump discharge flow rate can be obtained according to various conditions by controlling the metering throttle by the electronic control means. It can supply a sufficient flow rate when the pump discharge flow rate is required, and can set the flow rate to the minimum necessary when the steering assist force is not required. The flow rate can be ensured as necessary and sufficient and with high reliability.

According to the present invention, the power consumption for driving the pump is minimized, and the maximum energy saving effect can be obtained at low cost.

Further, according to the present invention, for example, a vehicle-mounted hydraulic pump, which is used as a hydraulic source of a power steering device, is controlled by electronic control means in accordance with running conditions such as a vehicle speed and a steering angle of the vehicle. By doing so, a comfortable steering feeling can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an embodiment of a variable displacement pump according to the present invention and illustrating a fluid pressure circuit structure using the pump.

FIG. 2 is a sectional side view of a main part of the variable displacement pump shown in FIG.

FIG. 3 is a characteristic diagram showing a supply flow rate characteristic during non-steering (during straight running) and steering with respect to vehicle speed when the variable displacement pump according to the present invention is used as a fluid pressure source of a power steering device.

FIG. 4 shows another embodiment of the variable displacement pump according to the present invention, and is a configuration diagram corresponding to FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Vane type variable displacement pump (variable displacement vane pump), 11 ... Front body (pump body), 12 ... Rear body (pump body), 14 ... Storage space, 15 ... Rotor, 15a ... Vane, 16 ... Drive shaft (Rotating shaft), 17 ... Cam ring, 17b ... Compression coil spring (biasing means), 18 ... Pump chamber, 19 ... Adapter ring, 20 ... Pressure plate, 21 ... Swinging fulcrum pin, 22 ... Suction side opening, 23 ... Discharge side opening, 25,
25a: suction side passage, 26: pump discharge side pressure chamber, 27
... Discharge side passage, 27a ... Discharge port, 30 ... Spool control valve, 31 ... Valve hole, 32 ... Spool, 33,
34: first and second fluid pressure chambers, 35: sealing material, 36 ...
Spring chamber, 36a: Compression coil spring, 37: Connection passage, 3
7a: damper throttle, 38: high pressure side chamber, 39: connection passage, 39a: damper throttle, 41, 42: pilot pressure passage, 42a: pilot throttle, 49: relief valve,
50: metering throttle, 51: pump discharge side passage, 5
3, 54, 58: passage holes, 55: small holes serving as fixed throttles,
56 ... Small hole to be a variable aperture, 57 ... Rod, 60 ... Solenoid (electronic drive means), 61 ... CPU (electronic control unit), 62 ... Drive circuit, 63 ... Vehicle speed sensor, 64 ... Rudder angle sensor, PS ... Pressure Fluid utilization equipment (power cylinder of power steering body), T ... tank.

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[Procedure amendment]

[Submission date] December 10, 1999 (1999.12.
10)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0046

[Correction method] Change

[Correction contents]

When the above-described control valve 30 is used, the fluid pressure chambers 33, 3 formed on both sides in the moving direction of the cam ring 17 despite the low operating pressure of the valve 30.
The fluid pressure on the pump suction side can be introduced into at least one of the four to make the working pressure . Therefore,
Since the fluid pressure difference between the fluid pressure chambers 33 and 34 can be increased, a reliable displacement of the cam ring 17 can be obtained.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0061

[Correction method] Change

[Correction contents]

FIG. 4 shows a modification of the variable displacement pump according to the present invention. The first and second fluid pressure chambers 33 and 34 for moving and displacing the cam ring 17 have pilot pressure passages 41 and 4 respectively.
2 shows an example in which fluid pressures on the metering throttle 50 and on the downstream side are directly introduced via the valve 2. According to this structure, the fluid pressure difference is smaller than the above-described embodiment, to Ru can achieve original transfer, there is no the control valve 30 minute cost for moving the cam ring 17 Reduction can be achieved .

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) // B62D 101: 00 B62D 101: 00 113: 00 113: 00 117: 00 117: 00 127: 00 127: 00 131: 00 131: 00 137: 00 137: 00 (72) Inventor Satoshi Ikeda 25 No.10, Namerikawa-cho, Hiki-gun, Saitama F-Term in Bosch Brake System Co., Ltd. (Reference) 3D032 CC08 CC33 CC34 CC35 CC49 DA03 DA09 DA23 DA50 DB11 EB11 EC03 EC05 GG01 3D033 EB02 EB04 EB06 3H040 AA03 BB01 BB11 CC09 CC22 DD23 DD28 DD33 DD37 DD38 3H044 AA02 BB05 CC19 CC22 DD10 DD24 DD26 DD34 DD43

Claims (8)

[Claims] 1. A cam ring which forms a pump chamber between a pump body and a rotor and is urged in a direction in which the pump capacity of the pump chamber is maximized, and the pump is provided on both sides in the moving direction of the cam ring. A first and a second fluid pressure chamber formed between the first and second fluid pressure chambers, and the cam ring is moved in a direction to increase or decrease the pump capacity of the pump chamber by a fluid pressure difference between the first and second fluid pressure chambers. A variable displacement pump which is displaceable, comprising: a metering throttle provided in a passage on a pump discharge side of the pump chamber; and electronic control means for variably controlling the metering throttle. . 2. The variable displacement pump according to claim 1, wherein the first and second fluid pressure chambers are provided at positions separated from the passage on the pump discharge side. . 3. The variable displacement pump according to claim 1, further comprising a control valve for controlling a fluid pressure in the first and second fluid pressure chambers. 4. The variable displacement pump according to claim 1, wherein the first fluid pressure chamber is set to a fluid pressure between an upstream side of the metering throttle and a pump suction side, and the second fluid pressure chamber is set to the second fluid pressure chamber. A variable displacement pump comprising control valves respectively connected to a pump suction side and a fluid pressure on a downstream side of the metering throttle. 5. The variable displacement pump according to claim 4, wherein a downstream side of the metering throttle is connected to one chamber of the control valve via a pilot throttle. 6. The variable displacement pump according to claim 1, wherein a pilot pressure passage branched from an upstream side of the metering throttle in the pump discharge side passage is connected to the first fluid pressure chamber and the meter is connected to the first fluid pressure chamber. A variable displacement pump wherein a pilot pressure passage branched from a downstream side of a ring throttle is connected to the second fluid pressure chamber. 7. The variable displacement pump according to claim 1, wherein said metering throttle comprises a fixed throttle and a variable throttle. 8. The variable displacement pump according to claim 1, wherein the variable displacement pump is a fluid pressure source of a power steering device, and the electronic control means is configured to input at least one of a vehicle speed and a steering angle. A variable displacement pump, which is a means for variably controlling the metering throttle.