JPH0524549A - Flow rate controller - Google Patents

Abstract

PURPOSE:To reduce the burden applied to the engine of a flow rate controller and reduce the production cost. CONSTITUTION:When the revolution speed of an engine increases and the discharge flow rate of a pump increases, the pressure acting to a front pressure chamber S3 increases, and the differential pressure between the parts before and behind a main orifice and a variable orifice increases, and a return flow rate adjusting spool 13 shifts to the left side against a spring, and a subpassage 6 and a bypass passage 7 communicate, and a portion of the discharge flow rate supplied from the pump returns to the suction side of the pump, passing through the bypass passage 7. Further, when the number of revolution of the engine increases and the discharge flow rate of the pump increases, the pressure difference between a feeding chamber S1 and an expansion chamber $2 increases, and a control spool 11 shifts to the left side against the sprigy force of the spring 12, and the opening area of the variable orifice 9 reduces, and the quantity of the pressurized fluid which flows into a power steering device 4 is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control device applied to a power steering device of an automobile.

[0002]

2. Description of the Related Art A flow rate control device applied to an automobile power steering device reduces the amount of pressure fluid supplied to the power steering device at high speed to make the steering wheel operation heavy to some extent, and a large amount of pressure fluid at low speed travel. There is a request to supply the power steering device to make the steering wheel lighter.

A flow rate control device disclosed in Japanese Patent Publication No. 1-27308 is known as a flow rate control device that meets the above demands. As shown in FIG. 4, this flow rate control device includes a main passage 1 connected to the pump housing 100 on the discharge side of the pump.
01 and the bypass passage 102 connected to the suction side of the pump
And a valve housing hole 103 is formed, a spool 104 is slidably housed in the valve housing hole 103, and a connector 106 connected to the power steering device 105 is attached to one end opening of the valve housing hole 103. The throttle member 107 is fixed in the connector 106 and the control spool 108 is slidably accommodated therein.
0, the downstream side supply chamber S1 ′ of the throttle member 107 and the rear pressure chamber S2 ′ of the spool 104 communicate with each other through a communication hole 109, and further, the connector 106 communicates with the pressure action chamber 110 of the control spool 108. Communication hole 111 and restricted passage 1
It has a structure in which 12 is formed.

Since the pump discharge amount is small while the pump rotation speed is low, the spool 104 is located on the left side of the position shown in the figure and closes the bypass passage 102 so that the entire pump discharge flow amount is reduced. It is supplied to the power steering device 105 through the member 107. Next, when the rotational speed of the engine increases and the discharge flow rate from the pump also increases, the spool 104 moves to the right side as shown in the figure in accordance with the pressure difference between the front and rear of the throttle member 107, and the fluid discharged from the pump is discharged. A portion returns to the pump via bypass passage 102. When the engine further rotates at high speed (the traveling speed is high) and the discharge flow rate from the pump becomes high, the fluid pressure in the main passage 101 rises due to the resistance in the restriction passage 112, and this raised pressure increases the control spool 1.
08 pressure acting chamber 110 and control spool 108.
The control spool 108 moves to the left in the drawing due to the pressure difference between the downstream side supply chamber S1 'and the throttle hole 107a of the throttle member 107 to limit the supply flow rate to the power steering device 105, and Is moved to the right in the figure, and the flow rate returning to the bypass passage 102 is increased to achieve balance.

[0005]

In the above-mentioned conventional device, the connector 106 is provided with the restriction passage 112 in order to move the control spool 108 due to the pressure difference. Then, since the excess flow returns to the bypass passage 102 via the restriction passage 112, a large pressure difference is required,
This will increase the load on the engine.

Further, in the conventional apparatus, the supply chamber S is provided in the housing 100 in order to keep the pressure drop across the throttle member 107 constant.
Although a communication hole 109 connecting between 1'and the rear pressure chamber S2 'is formed, in order to form this communication hole 109, three straight holes and a blind plug must be provided, which leads to compactness. The work is troublesome and costly.

[0007]

In order to solve the above-mentioned problems, a flow rate control device according to the first invention of the present application includes a valve housing hole in a housing, a main passage for supplying a pressure fluid from the pump to a power steering device, and a pump. A sub-passage for introducing an excess flow of the pressure fluid into the valve storage hole and a bypass passage for returning the excess flow flowing into the valve storage hole to the suction side of the pump, and the main passage for the valve storage hole. A control valve (spool) for controlling the amount of fluid flowing from the engine to the power steering device in accordance with the discharge flow rate of the pump, and a return flow rate adjusting spool for controlling the opening area of the bypass passage in accordance with the discharge flow rate of the pump. Are housed opposite to each other, and a rear pressure chamber is provided between the control valve and the return flow rate adjusting spool, and the control valve is placed between the rear pressure chamber and the rear pressure chamber. The chamber opposite to the relay chamber in which the main passage is opened, the return said opposite side of the rear pressure chamber across the flow regulating spool sub passage has a pressure chamber prior to opening.

Further, in the flow rate control device according to the second invention of the present application, a connector having a supply passage to the power steering device is fixed to one end opening of the valve accommodating hole formed in the housing, and the control spool is slid in the connector. A variable orifice whose opening area is changed by sliding the control spool is formed on the side wall of the connector, and the expansion between the control spool and the connector communicates with the main passage formed in the housing through the communication hole. Forming a chamber,
The position of the control spool is changed by the pressure difference between the expansion chamber and the relay chamber downstream of the variable orifice.

[0009]

A part of the pressure fluid discharged from the pump is supplied to the power steering device via the main passage, the control valve and the supply passage, while the remaining pressure fluid discharged from the pump is supplied to the sub passage, the front pressure chamber and the bypass. Return to the suction side of the pump through the passage.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is an overall view in which a part of the flow rate control device according to the present invention is shown in section, FIG. 2 is an enlarged cross-sectional view of a main part of the flow rate control device, and FIG. 3 is a diagram for explaining the operation of the flow rate control device. FIG.

The housing 1 serves both as a housing for accommodating the pump 2 and a housing for accommodating the flow rate control device. A valve accommodating hole 3 having one end opened is formed in the housing 1, and the valve accommodating hole 3 is provided with a valve accommodating hole 3 from the pump 2. The main passage 5 that supplies the pressure fluid to the power steering device 4, the sub passage 6 in which the remaining excess flow of the pressure fluid from the pump 2 flows, and the excess flow that has flowed into the valve housing hole 3 are returned to the suction side of the pump. The bypass passages 7 are opened respectively.

A tubular connector 9 having a supply passage 8 to the actuator 4 of the power steering device is screwed into one end of the valve accommodating hole 3, and a seat member 10 is fixed in the connector 9 to secure the seat. A control spool 11 as a control valve is slidably provided in the connector 9 on the upstream side of the member 10, and the control spool 11 is biased inward in a relay chamber S1 between the seat member 10 and the control spool 11. The spring 12 is arranged.

A main orifice 9a and a variable orifice 9b are formed on the side wall of the connector 9, and the tip end of the control spool 11 is inserted into the tip hole of the connector 9 with the partition wall 11a as a boundary to face the relay chamber S1. The variable orifice 9 is slidably in contact with the inner peripheral surface of the connector 9
a large diameter portion 11b for controlling the opening area of b, and a small diameter portion 11c arranged with a gap between the large diameter portion 11b and the connector side wall for rectifying the pressure fluid from the orifices 9a, 9b formed in the connector side wall, An expansion chamber S2 is formed between the control spool 11 and the inner bottom portion of the connector 9, and the expansion chamber S2 and the main passage 5 are communicated with each other through a communication hole 9c formed in the connector 9.

On the other hand, a return flow rate adjusting spool 13 is slidably arranged in the valve housing hole 3 of the housing. The return flow rate adjusting spool 13 is for controlling the return amount of the pressurized fluid to the pump 2, and the front pressure at which the sub passage 6 is opened between the return flow rate adjusting spool 13 and the inner bottom of the valve housing hole 3. The connector 9 which is the chamber S3 and accommodates the return flow rate adjusting spool 13 and the control spool 11
A rear pressure chamber S4 is provided between the and.

The rear pressure chamber S4 and the relay chamber S1
Is communicated via a damper orifice 11d formed in the partition wall portion 11a of the control spool 11, and the internal pressure of the relay chamber S1 acts on the rear pressure chamber S4.

Further, an axial valve accommodating hole 14 is formed in the return flow rate adjusting spool 13, and this valve accommodating hole 14 is formed.
A check valve 15 is provided inside, and when the pressure in the rear pressure chamber S4 rises, the check valve 15 opens and
The pressure fluid inside is returned to the bypass passage 7.

In the above, the engine speed is low,
When the discharge flow rate of the pump 2 is small, in other words, when the traveling speed is slow, as shown in FIG. 2, the pressure fluid discharged from the pump 2 is supplied to the main passage 5, the main orifice 9a, the variable orifice 9b, the relay chamber S1 and the supply chamber. It flows into the power steering device 4 via the passage 8.

When the engine speed is low, the flow rate adjusting spool 13 is pushed to the right side in the figure by the elastic force of the spring 16, the communication between the sub passage 6 and the bypass passage 7 is cut off, and the pump is disconnected from the pump. The entire discharge flow rate of is supplied to the power steering device 4 through the passage, and the steering wheel can be operated with a small force.

Next, when the engine speed increases and the discharge flow rate from the pump increases, the pressure acting on the front pressure chamber S3 increases, and as a result, the flow rate adjusting spool 13 resists the spring 16 and moves to the left side in the figure. The sub passage 6 and the bypass passage 7 are moved to communicate with each other, and a part of the discharge flow rate from the pump is circulated to the suction side of the pump through the bypass passage 7. At this time, since the flow rate supplied to the power steering device 4 is also increasing, the steering wheel operating force is further reduced.

As the engine speed further increases, the pump 2
When the discharge flow rate of the control spool 11 increases, in other words, when the traveling speed increases, the pressure difference between the relay chamber S1 and the expansion chamber S2 increases, and as shown in FIG. Moves to the left side in the figure, the opening area of the variable orifice 9b is reduced, and the power steering device 4
Reduce the amount of pressure fluid flowing into. As a result, when the engine speed is high, that is, when the vehicle is traveling at high speed, an appropriate resistance is generated in the steering wheel operation.

[0021]

As described above, in the flow rate control device according to the present invention, the fluid returning to the pump does not enter the bypass passage through the restriction passage but directly enters the bypass passage unlike the conventional device. The pressure difference between the pump pressure and the supply passage to the power steering device is reduced, torque increase can be prevented, and the engine output can be distributed efficiently.

Further, since the structure of the flow rate control device is such that the rear pressure chamber of the spool that recirculates the excess flow to the suction side of the pump is provided in the portion near the control valve (control spool), the spool is moved. It suffices to form an orifice that connects the rear pressure chamber and the supply passage, for example, in the control valve without forming a long passage for the purpose in the housing.

[Brief description of drawings]

FIG. 1 is an overall view of a cross section of a part of a flow rate control device according to the present invention.

FIG. 2 is an enlarged cross-sectional view of the main part of the same flow control device.

FIG. 3 is an enlarged sectional view of an essential part for explaining the operation of the flow rate control device.

FIG. 4 is an enlarged sectional view of a main part of a conventional flow control device.

[Explanation of symbols]

1 ... Housing, 2 ... Pump, 3 ... Valve storage hole, 5 ...
Main passage, 6 ... Sub passage, 7 ... Bypass passage, 8 ... Supply passage, 9 ... Connector, 10 ... Seat member, 11 ... Control valve, 13 ... Spool, S1 ... Relay chamber, S2
... annular chamber, S2 ... expansion chamber, S3 ... front pressure chamber, S4 ... rear pressure chamber.

Claims (4)

[Claims] 1. A flow control device for limiting the amount of fluid supplied to a power steering device according to a discharge flow rate of a pump, wherein a housing of the flow control device has a valve accommodating hole and pressure fluid from the pump is supplied to the power steering device. A sub-passage for supplying an excess flow of the pressure fluid from the pump to the valve storage hole and a bypass passage for returning the excess flow flowing into the valve storage hole to the suction side of the pump. A control valve for controlling the amount of fluid flowing from the main passage to the supply passage to the power steering device according to the discharge flow rate of the pump and an opening area of the bypass passage according to the discharge flow rate of the pump are provided in the valve storage hole. The return flow rate adjusting spool to be controlled is housed facing each other, and the space between these control valve and the return flow rate adjusting spool is stored. Is a rear pressure chamber, a side opposite to the rear pressure chamber across the control valve is a relay chamber in which the main passage is opened, and a side opposite to the rear pressure chamber across the return flow rate adjusting spool is opened in the sub passage. A flow rate control device characterized in that it is a front pressure chamber. 2. The control valve is a spool valve, and the spool valve is formed with an orifice that connects the rear pressure chamber and the relay chamber.
The flow control device according to. 3. A flow control device for limiting the amount of fluid supplied to a power steering device according to a discharge flow rate of a pump, wherein a valve housing hole formed in a housing of the flow control device is provided at one end opening of the power steering device. A connector having a supply passage is fixed, a control spool is slidably accommodated in the connector, and a variable orifice whose opening area is changed by sliding of the control spool is formed on the connector side wall. An expansion chamber that communicates with a main passage formed in the housing through a communication hole is formed between the expansion chamber and the relay chamber downstream of the variable orifice so that the position of the control spool changes. A flow control device characterized by the above. 4. A large-diameter portion, which slidably contacts the inner peripheral surface of the connector on the side wall of the control spool and controls the opening area of the variable orifice, and a connector for rectifying the pressure fluid from the orifice formed in the connector side wall. The flow control device according to claim 3, further comprising a small-diameter portion arranged with a gap between the side wall and the side wall.