JPH09175418A - Flow controller for power steering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow rate control device for power steering which supplies pressurized fluid discharged from a pump of which discharge amount increases in response to the speed of engine to a power steering device of a vehicle via a reduction passage, and which returns excessive pressurized fluid to a drain by means of a flow rate control spool valve. SOLUTION: In a hole 4 for accommodating a spool in which a spool valve 5 for controlling the flow rate, a pump discharge 6 and a return passage are opened with a specified distance, and the hole 4 is partitioned by the valve 5 into a primary pressure valve chamber 11 and a reverse side valve chamber. The reverse side valve chamber is partitioned by a partitioning member 9 into a secondary pressure valve chamber 12 near the return passage and a pressure oil supply chamber 13, and a communication passage 15 is formed at the valve 5. An end of tubular member 16 is attached to an end of the secondary pressure valve chamber 12 and a through hole 17 is formed at the partitioning member 9 with respect to the tubular member 16. In the chamber 13 a member 18 is positioned to reduce the opening of the tubular member 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supplies pressure fluid discharged from a pump whose pump discharge flow rate increases in accordance with the number of rotations of a pump to a power steering device of a vehicle through a throttle passage in a supply passage. The present invention relates to a power steering flow rate control device for returning excess pressure fluid to a drain by a flow rate adjustment spool valve that adjusts the opening degree of a bypass passage.

[0002]

2. Description of the Related Art A conventional pump rotation speed sensitive flow control device 01
Were configured as shown in FIG.

A hydraulic pump 03 is integrally incorporated in a casing 02 of a pump speed-sensitive flow rate control device 01, and a spool accommodating hole 04 is formed in the casing 02.
A flow passage adjusting spool 05 is slidably fitted to 04, and a discharge passage 06 and a return passage which communicate with the discharge port 03a of the hydraulic pump 03 and the suction port (not shown) of the hydraulic pump 03, respectively.
07 is opened in the spool housing hole 04 at a predetermined distance in the axial direction.

A connector 08 for connecting the power steering device is mounted on the end of the spool housing hole 04 on the discharge passage 06 side, a through hole 08b is formed in a base portion 08a of the connector 08, and a shaft of the flow rate adjusting spool 05 is formed. The variable throttle passage 010 is constituted by the throttle valve body 09 provided in the portion 05a and the connector through hole 08b.

Further, in the spool accommodating hole 04, the flow rate adjusting spool 05 separates the first hydraulic valve chamber 011 on the connector 08 side from the second hydraulic valve chamber 012 on the opposite side, and the connector 08 A pressure oil supply chamber 013 is formed at the end of the first hydraulic valve chamber 011 by the base portion 08a, and a compression coil spring 014 is interposed in the second hydraulic valve chamber 012. The second hydraulic valve chamber 012 is a communication passage 015 that is parallel to the spool accommodating hole 04, and a hole 016 and a throttle 017 that open at both ends of the communication passage 015 to the first hydraulic valve chamber 011 and the second hydraulic valve chamber 012, respectively. Therefore, the communication passage 015, the hole 016, and the throttle 017 are communicated with each other and are formed in the casing 02, and when the discharge pressure of the hydraulic pump 03 is low, the flow rate is adjusted by the spring force of the compression coil spring 014. Spool 05 is pushed to connector 08 side Te, recirculation passage 07 to the discharge passage 06, and is closed with a flow rate adjusting spool 05.

In the conventional pump speed-sensitive flow rate control device 01 shown in FIG. 9, a communication passage 015, a hole 016 and a throttle 017 which connect the first hydraulic valve chamber 011 and the second hydraulic valve chamber 012 to each other. Since it is necessary to form the casing 02 in the casing 02 and seal the open ends of the communication passage 015 and the throttle 017 with the stoppers 018 and 019, not only the sealing work is complicated but also this sealing is not proper. If so, oil leakage may occur, and burrs may occur when the diaphragm 017 is processed.

As a solution to such a problem,
As shown in FIG. 10 (see Japanese Utility Model Publication No. 7-14113), a pin hole oriented in the axial direction of the flow rate adjusting spool 021.
022 is formed at the tip of the flow rate adjusting spool 021, the base end of the throttle valve body 023 is fitted in the pin hole 022, and the passage 024 with throttle is formed in the throttle valve body 023. A first oblique communication passage 025 is formed at the front end of the flow rate adjusting spool 021 so as to communicate with the oblique direction so as to communicate the first oblique communication passage 025 with the second hydraulic valve chamber 012. Communication passage
There was a pump speed-sensitive flow control device 020 in which 026 was formed on the flow control spool 021.

[0008]

In a pump speed-sensitive flow control device 020 shown in FIG. 10, a communication path is connected to a casing 02 like the pump speed-sensitive flow control device 01 shown in FIG.
Although it is not necessary to form 015, hole 016 and throttle 017, a throttle valve body 023 is prepared separately from the flow rate adjusting spool 021 and a pin hole 022 is provided at the tip of the flow rate adjusting spool 021.
And the throttle valve body 023 and the flow rate adjusting spool 021 are provided with a throttled passage 024 and a first oblique communication passage.
025 and the second oblique communication passage 026 must be formed, and in order to fully exert the function of the variable throttle passage constituted by the connector and the throttle valve body 023, the pin hole 022 and the throttle valve body It was necessary to maintain the processing accuracy of 023 at a high level, and it was difficult to form the first oblique communication passage 025 and the second oblique communication passage 026 in the flow adjustment spool 021 in the oblique direction.

[0009]

SUMMARY OF THE INVENTION The present invention relates to an improvement of a power steering flow rate control device that overcomes the above problems, and relates to a pump in which the pump discharge flow rate increases in response to an increase in the pump rotation speed. The flow rate for power steering in which the discharged pressure fluid is supplied to the power steering device of the vehicle through the throttle passage in the supply passage and the excess pressure fluid is returned to the drain by the flow adjustment spool valve that adjusts the opening degree of the return passage. In the control device, a pump discharge passage and a recirculation passage are opened through a predetermined distance in the axial direction in a spool housing hole in which the flow rate adjusting spool valve is slidably fitted, and the flow rate adjusting spool valve is used to The spool accommodating hole is partitioned into a primary pressure valve chamber and a valve chamber on the opposite side, and the valve chamber on the opposite side is circulated by a partition member that traverses the valve chamber. A communication passage that is partitioned into a secondary pressure valve chamber near the passage and a pressure oil supply chamber that communicates with the power steering device near the end of the spool housing hole, and that axially penetrates through the flow adjustment spool valve, adjusts the flow. One end of a tubular member formed in the spool valve for use in the secondary pressure valve chamber of the communication passage and oriented in a direction parallel to the axial direction of the flow rate adjusting spool is attached to the tubular member. It is characterized in that a diaphragm is formed by forming through holes in the partition member so that they can be loosely fitted at intervals.

Since the present invention is constructed as described above, when the pump speed is in the low speed range, the flow rate adjusting spool valve blocks the communication between the pump discharge passage and the return passage. The pump discharge pressure fluid does not flow back to the suction side of the pump, the entire amount is supplied to the power steering device of the vehicle, and the supply flow rate thereof increases in accordance with the increase in the pump rotation speed.

When the pump rotation speed reaches the medium speed rotation range, the pump discharge passage and the return passage are communicated with each other, and a part of the pump discharge pressure fluid increases by an increase in the pump discharge amount. The supply flow rate to the pump is kept constant regardless of the increase in the pump rotation speed.

According to the present invention, when the pump speed increases beyond the medium speed range, the flow rate adjusting spool moves to the pressure oil supply chamber, The throttle member relatively enters into the opening in the tubular member integrated with the flow rate adjusting spool, and the tubular member is throttled,
The supply flow rate to the power steering device decreases as the pump speed increases.

When the pump rotational speed further increases to a certain rotational speed or more, the flow rate of the supply to the power steering device does not decrease due to the progress of the throttle of the tubular member, and the flow rate of the power steering device is kept constant. To be done.

Further, in the present invention, the primary pressure valve chamber and the pressure oil supply chamber have a communication passage axially penetrating the inside of the flow rate adjusting spool valve and a secondary pressure valve chamber of the communication passage. Since it is communicated with the tubular member attached to the end and the throttle is formed by the communication passage and the hole in the tubular member, it is necessary to form the communication passage and the throttle in the casing as in the conventional one. It is easy to process and the number of parts is small.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention shown in FIGS. 1 to 4 will be described below.

A hydraulic pump 3 driven by a belt from an engine (not shown) is integrally incorporated in a casing 2 of a pump rotation speed-sensitive power steering flow rate control device 1. The hydraulic pump 3 is proportional to the rotational speed of the engine. It is supposed to increase and decrease.

A spool accommodating hole 4 is formed in the casing 2, and a flow rate adjusting spool 5 is slidably fitted in the spool accommodating hole 4 and is opened in the spool accommodating hole 4 at a predetermined distance in the axial direction. A discharge passage 6 and a return passage 7 (the discharge passage 6 is located on the right side and the return passage 7 is located on the left side in the drawing), and the discharge passage 6 communicates with the discharge port 3a of the hydraulic pump 3. At the same time, the return passage 7 communicates with a suction port (not shown) of the hydraulic pump 3.

Further, the return passage 7 of the flow rate adjusting spool 5 is provided.
A connector 8 for connecting a pipe communicating with a power steering device (not shown) is screwed to the side end (left end).

Furthermore, a partition plate 9 is fitted in the spool housing hole 4 located between the flow rate adjusting spool 5 and the connector 8, and the partition plate 9 is fixed by a circlip 10 so that the spool housing hole 4 can be secured. Inside, a primary pressure valve chamber 11 is provided to the right of the flow rate adjusting spool 5, a secondary pressure valve chamber 12 is provided between the flow rate adjusting spool 5 and the partition plate 9, a connector 8 and a partition plate 9 are provided.
And the pressure oil supply chamber 13 are partitioned from each other, and a compression coil spring 14 is interposed in the secondary pressure valve chamber 12.

Moreover, the inter-flow-rate adjusting spool 5 is penetrated by the communicating passage 15 oriented in the axial direction, and the pipe 16 has a proximal end fitted to the end of the communicating passage 15 on the secondary pressure valve chamber 12 side. The partition plate 9 is formed with a communication hole 17 into which the pipe 16 can be loosely fitted with a required space, and a throttle projection piece 18 supports the tip of the connector 8 on the extension line of the pipe 16 so as to face the tip thereof. The passage 19 is provided in the portion 19 and is formed by the communication hole 17 of the partition plate 9 and the pipe 16.
In addition, the front end of the pipe 16 and the aperture projecting piece 18 form an aperture 21.

A relief valve 22 is provided in the flow rate adjusting spool 5 as shown in FIGS. 1 and 4, and the pressure oil pressure in the primary pressure valve chamber 11 rises, The pressure increase is transmitted to the secondary pressure valve chamber 12 through the communication passage 15, the pipe 16, the throttle passage 20 and the throttle 21, and the secondary pressure valve chamber 12
When the pressure oil pressure inside has risen above a predetermined pressure, the relief valve 22 opens, and the pressure oil pressure inside the secondary pressure valve chamber 12 decreases, causing the flow rate adjusting spool 5 to move to the left, thereby reducing the hydraulic pressure. The pressure oil discharged from the pump 3 and flowing into the pressure oil supply chamber 13 can return to the return passage 7.

The embodiment illustrated in FIGS.
Since it is configured as described above, when the hydraulic pump 3 is stopped and pressure oil is not generated, the flow rate adjusting spool 5 and the pipe 16 are the springs of the compression coil spring 14 as shown in FIG. The force moves to the right, the right end of the flow rate adjusting spool 5 is in contact with the right end of the spool housing hole 4, the discharge passage 6 and the return passage 7 are blocked, and the throttle 21 is closed. The area is set to the maximum value.

In the state shown in FIG. 1, when the hydraulic pump 3 is rotated at a predetermined rotation speed Na or less, the pressure oil generated in the hydraulic pump 3 is discharged from the spool storage hole 4 through the discharge passage 6. It flows into the primary pressure valve chamber 11 and communicates with the communication passage 15 and the pipe 16.
Through the pressure oil supply chamber 13 and is supplied to a control valve of a power steering device (not shown). However, even if the pressure oil pressure P ₁ in the primary pressure valve chamber 11 rises to overcome the spring force of the compression coil spring 14 and the flow rate adjusting spool 5 moves to the left, the amount of movement is small, The return passage 7 remains closed, and as shown in FIG. 8A, all the pressure oil generated by the hydraulic pump 3 in proportion to the engine speed is supplied to the control valve of the power steering device. To be done.

Further, the hydraulic pump 3 has a predetermined low speed rotation Na.
When it rotates in the mid-rotation range until it reaches a predetermined rotation speed Nb higher than this, the flow rate adjusting spool is increased by increasing the pressure oil pressure P ₁ in the primary pressure valve chamber 11 of the spool accommodating hole 4. 5 moves further to the left, as shown in FIG.
The return passage 7 communicates with the discharge passage 6, and the communication opening area thereof increases as the flow rate of the hydraulic pump 3 increases.
As shown in b of FIG. 8, a substantially constant flow rate of pressure oil is supplied to the control valve of the power steering device.

Further, the hydraulic pump 3 has a predetermined middle rotation speed Nb.
Exceeding the pressure oil pressure P ₁ in the primary pressure valve chamber 11 and the pressure oil pressure P ₃ in the secondary pressure valve chamber 12 corresponding to the pressure oil pressure P ₂ in the pressure oil supply chamber 13 (pressure oil Even if the pressure oil pressure P ₂ in the supply chamber 13 fluctuates, the throttle passage 20 allows the pressure oil pressure P 2 in the secondary pressure valve chamber 12 to change.
₃ is capable of maintaining a substantially constant pressure without being affected so much by the pressure fluctuation), and as shown in FIG. 3, the flow rate adjusting spool 5 changes the spring force of the compression coil spring 14. Overcome, the flow rate adjusting spool 5 moves further to the left, the throttle 21 is throttled, and throttled from the primary pressure valve chamber 11.
Since the flow rate of the pressure oil flowing into the pressure oil supply chamber 13 via 21 decreases, as shown in FIG. 8C, the pressure oil is supplied to the control valve of the power steering device in response to the increase in the rotation speed of the hydraulic pump 3. The flow rate of the pressure oil to be reduced decreases.

When the hydraulic pump 3 reaches a predetermined high speed Nc, the pressure difference between the pressure oil pressure P ₁ in the primary pressure valve chamber 11 and the pressure oil pressure P ₃ in the secondary pressure valve chamber 12 is reached. With the increase of
The flow rate adjusting spool 5 moves further to the left and the throttle 21
Is throttled to a limited throttle state, and the increase in the discharge flow rate of the hydraulic pump 3 flows into the return passage 7. Therefore, the pressure oil flow rate from the pressure oil supply chamber 13 to the control valve of the power steering device is a low level constant flow rate. Held in.

When the pressure oil pressure P ₂ in the pressure oil supply chamber 13 reaches a predetermined increased pressure for some reason, the pressure oil pressure P ₃ in the secondary pressure valve chamber 12 also rises. , Relief valve 22
Is released and the pressure oil in the secondary pressure valve chamber 12 is discharged to the return passage 7, so that the flow rate adjusting spool 5 moves to the left and all the pressure oil passing through the discharge passage 6 is returned to the return passage 7. All flow.

As described above, in this embodiment, the casing 2
Since it is not necessary to provide a communication passage or a throttle for communicating the primary pressure valve chamber 11 with the pressure oil supply chamber 13, it is easy to process the pump rotation speed sensitive power steering flow rate control device 1 and parts There are also few points.

In the above embodiment, the connector 8 and the partition plate 9
Although it was a separate body, the connector 8, the partition plate 9 and the diaphragm projection piece
18 may be integrally formed.

The communication passage 15 and the pipe 16 may be formed so as to be aligned with the center of the spool housing hole 4.

Further, as shown in FIG. 5, the tip end opening of the pipe 16 fitted in the communication passage 15 of the flow rate adjusting spool 5
By arranging the communication passage 15 and the pipe 16 so that a part of 16a is located closer to the center of the spool housing hole 4 than the cylindrical inner peripheral surface 8a of the connector 8, the tip of the pipe 16 is located at the end surface 8b of the connector 8. When it comes close to, a part of the end opening 16a of the pipe 16 is covered with the end face 8b of the connector 8 and the diaphragm 21
May be formed.

Further, as shown in FIG. 6, an annular groove 23 is formed in the end surface 8b of the connector 8 and the pipe is
By forming the tip portion 16b of 16 obliquely, the annular groove 23
The diaphragm 21 may be configured by the front end inclined opening surface 16b of the pipe 16.

Moreover, as shown in FIG. 7, the connector 8
The inner peripheral surface 8c of the end of the pipe is formed into a conical surface which is tapered toward the inner side, and the distal end portion 16c of the pipe 16 is obliquely cut so as to be substantially parallel to the conical surface 8c. You may form.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view showing an embodiment of a power steering flow rate control device of the present invention in a pump stopped state.

FIG. 2 is a vertical cross-sectional side view showing a state in which the pump rotates in the medium speed rotation range.

FIG. 3 is a vertical cross-sectional side view showing a state where the pump rotates in a high speed rotation range.

FIG. 4 is a vertical cross-sectional side view with a relief valve opened.

FIG. 5 is a vertical sectional side view of another embodiment of the present invention.

FIG. 6 is a vertical sectional side view of still another embodiment of the present invention.

FIG. 7 is a vertical cross-sectional side view of yet another embodiment of the present invention.

FIG. 8 is a characteristic diagram of the embodiment.

FIG. 9 is a vertical cross-sectional side view of a conventional power steering flow rate control device.

FIG. 10 is a vertical sectional side view of another conventional flow control device for power steering.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pump rotation speed-sensitive power steering flow control device, 2 ... Casing, 3 ... Hydraulic pump, 4 ... Spool storage hole, 5 ... Flow rate adjusting spool, 6 ... Discharge passage, 7 ...
Reflux passage, 8 ... Connector, 9 ... Partition plate, 10 ... Circlip, 11 ... Primary pressure valve chamber, 12 ... Secondary pressure valve chamber, 13 ... Pressure oil supply chamber, 14 ... Compression coil spring, 15 ... Communication passage , 16 ... pipe, 17 ... communication hole, 18 ... throttle projection, 19 ... support portion, 20 ... throttle passage, 21 ... throttle, 22 ... relief valve, 23 ... annular groove.

Claims (3)

[Claims] 1. A pressure fluid discharged from a pump whose pump discharge flow rate increases in response to an increase in the pump rotational speed is supplied to a power steering device of a vehicle through a throttle passage in a supply passage to recirculate excess pressure fluid. In a power steering flow control device for returning to a drain by a flow control spool valve that adjusts the opening of a passage, in a spool accommodating hole in which the flow control spool valve is slidably fitted, a predetermined distance is provided in the axial direction. A pump discharge passage and a recirculation passage are opened, the spool accommodating hole is partitioned by the flow rate adjusting spool valve into a primary pressure valve chamber and an opposite side valve chamber, and the opposite side valve chamber is A partition member that crosses the chamber divides the secondary pressure valve chamber near the return passage and the pressure oil supply chamber communicating with the power steering device near the end of the spool housing hole. A throttle passage that penetrates the amount adjusting spool valve in the axial direction is formed integrally with the flow adjusting spool valve, and the secondary pressure valve chamber end portion of the communicating passage is parallel to the axial direction of the flow adjusting spool. One end of a tubular member oriented in any direction is attached, and a through hole is formed in the partition member so that the tubular member can be loosely fitted to the tubular member at a required interval, thereby forming a diaphragm. A flow control device for power steering, which is characterized in that 2. A throttle member for squeezing an opening of the tubular member is provided in the pressure oil supply chamber in a state where the flow rate adjusting spool valve approaches the pressure oil supply chamber. The flow control device for power steering according to claim 1, wherein: 3. The flow control spool valve includes the
The relief valve according to claim 1, further comprising a relief valve for discharging the pressure fluid from the secondary pressure valve chamber to the recirculation passage when the pressure fluid pressure in the secondary pressure valve chamber exceeds a predetermined pressure. Item 2. A flow control device for power steering according to item 2.