JPS61200061A - Flow-rate controller for power steering apparatus - Google Patents

Abstract

PURPOSE:To eliminate the inutile power consumption by operating a spool valve for adjusting flow rate to the position for largely opening a bypass passage when handle operation is not performed and forming the operation state for throttling a throttle passage, thus reducing the flow rate of the pressurized fluid when steering operation is not performed. CONSTITUTION:When a steering wheel is not operated, a driving circuit 30 is operated by a control circuit 31. A solenoid 29 is excited, and the first slidable part 26 of a plunger 24 is attracted to a yoke 27 side against a spring 28, and a throttle passage 13 is closed by the second slidable part 26 of the plunger 24. Further, a spool valve 17 is pushed by the pusher part 25a of the plunger 24, and said spool valve 17 is moved leftward against a spring 20. Therefore, a bypass passage 16 is perfectly opened, and all the amount of the pressurized fluid which is supplied from a pump 14 is returned to the suction side of the pump 14 through passages 15 and 16. Therefore, the pressure loss is reduced, and the inutile power consumption of the pump 14 is reduced. When the steering wheel is operated, the solenoid 29 is put into nonexcitation state, and the state as shown in the figure is formed.

Description

[Detailed description of the invention] Industrial application field> The present invention sends pressurized fluid discharged from a pump to a power steering device through a throttle passage, and returns surplus flow to the suction boat side through a bypass passage. The present invention relates to a flow control device for a power steering device.

<Prior Art> A flow rate control device for a power steering device is used to control the flow rate of pressurized fluid supplied from a pump driven by an automobile engine to a power steering device to a constant flow rate when the engine speed exceeds a predetermined rotation speed. is used. In this system, a throttle passage is provided in the middle of the flow path that leads the pressure fluid from the pump to the power steering device, and a bypass passage that communicates with the suction boat side of the pump is opened in response to the differential pressure before and after the throttle passage. A flow rate adjustment spool is provided to adjust the flow rate.

<Problems to be Solved by the Invention> The above-described flow control device supplies a constant flow rate of pressure fluid to the power steering device even when the steering wheel is not operated, so There was a problem in that pressure loss occurred due to such factors, and the horsepower of the pump was wasted.

and solve problems. Means for Pursuing> In order to solve the above-mentioned problems, the present invention provides an actuating means that operates and throttles the throttle passage.

<Function> With the above configuration, when the handle is not operated,
The operating means moves the flow rate adjusting spool valve to a position where the bypass passage is wide open, and the throttle passage is throttled, so that the power steering device is supplied with zero or a very small flow rate of pressure fluid. When the handle is operated in such a state, the flow rate adjustment spool valve moves in the direction of closing the bypass passage and at the same time opens the throttle passage, and the power steering device receives pressurized fluid with a flow rate necessary for operating the power steering device. Supplied.

<Example> Embodiments of the present invention will be described below based on the drawings.

In FIGS. 1 and 2, 10 is a housing;
A first valve hole 11 and a second valve hole 12 are formed in this housing 10 . First valve hole 11 and second valve hole 1
A throttle passage 13 is formed between the two to communicate with each other. A supply passage 15 communicating with the discharge port of the pump 14 and a bypass passage 16 communicating with the suction port of the pump 14 are opened in the first valve hole 11 and spaced apart in the axial direction.

The first valve hole 11 has a supply passage 15 and a bypass passage 1.
A spool valve 17 for adjusting the flow rate that opens and closes the communication path with the first
The valve hole 11 is divided into a first valve chamber 18 and a second valve chamber 19 communicating with the throttle passage 13 and the supply passage 15. The spool valve 17 is placed in the second valve chamber 19 and the spool valve 17 is placed in the first valve chamber 18ff.
,! A spring 20 that presses toward J is provided.

A delivery passage 22 communicating with a servo valve 21 of the power steering device is opened in the second valve hole 12, and a second valve chamber 19 is opened in the second valve hole 12.
A communication path 23 is opened. This communication path 23
As a result, the pressure of the fluid before and after passing through the throttle passage 13 acts on the end face of the spool valve 17. A plunger 24 is slidably inserted into the second valve hole 12, and the plunger 24 has a first sliding portion 25 and a second sliding portion that protrude in the radial direction at positions spaced apart from each other in the axial direction. A throttle passage 1 in which a portion 26 is formed and a spool valve 17 is pressed against the tip thereof.
A bushing portion 25a having a diameter smaller than that of 3 is formed.

The first sliding portion 25 is a magnetic material, and the second sliding portion 26 is a non-magnetic material. The area of the flow path that communicates the first valve chamber 18 and the second valve hole 12 is the area that opens between the throttle passage 13 and the button portion 25a when the plunger 24 moves to the right, and the area that opens between the throttle passage 13 and the bushing portion 25a when the plunger 24 moves to the left When the throttle passage 13 is closed by the second sliding portion 26, it becomes zero. The second sliding portion between the first sliding portion 25 and the second sliding portion 26
A yoke 27 is formed in the valve hole 12 and projects radially inward, and a spring 28 is inserted between the yoke 27 and the first sliding portion 25 . A solenoid 29 is provided around the yoke 27, and when a current is applied to the solenoid 29, the first sliding portion 25 is attracted toward the yoke 27.

It looks like this. The plunger 24 and yoke 2 described above
7. Solenoid valve 4 by spring 28 and solenoid 29
0 is configured.

30 is a drive circuit that controls the current applied to the solenoid 29, and 31 is a control circuit that controls the operation of the drive circuit 30. A signal indicating whether or not the handle is operated is input to the control circuit 31.

The servo valve 21 is equipped with a plurality of throttles 32, 33, and when the handle is operated, one of the throttles is closed and the other throttle is opened. This servo valve 21
The pressure fluid whose distribution is controlled by is guided to the cylinder device 34.

Next, the operation will be explained based on the above-described configuration. When the steering wheel is not operated, the control circuit 31
The drive circuit 30 is activated, and current is supplied from the drive circuit 30 to the solenoid 29. By supplying current to the solenoid 29, the first sliding portion 25 overcomes the spring 28 and is attracted toward the yoke 27, and the throttle passage 13 is closed by the second sliding portion 26. As the plunger 24 moves to the left, the spool valve 17 is pressed by the plunger portion 25a, so that the spool valve 1
7 overcomes the spring 20 and moves to the left, and the bypass passage 16 becomes fully open. In this state, the entire amount of the pressure fluid from the pump 14 is returned to the suction port side of the pump 14 via the supply passage 15, the first valve chamber 18, and the bypass passage 16. At this time, the bypass passage 16 has a sufficient opening area despite the discharge flow rate from the pump 14, and the supply passage 15, the first valve chamber 18
Since the pressure loss of the oil passing through the bypass passage 16 is extremely small, the horsepower consumption of the pump 14 is extremely low.

When the steering wheel is operated, a steering wheel steering signal is input to the control circuit 31, and the current supplied from the drive circuit 30 to the solenoid 29 is stopped. As a result, the plunger 24 is moved to the right by the spring 28, and the area of the flow path connecting the first valve chamber 18 and the second valve hole 12 becomes the opening area between the throttle passage 13 and the bushing portion 25a. As the plunger 24 moves to the right, the spool valve 1 that has been pushed by the plunger 24 until now
7 moves to the right by the spring 20, and the bypass passage 16
The area of the opening is reduced to keep the differential pressure before and after the throttle constant. As a result, the cylinder device 34 is supplied with the flow rate necessary for its operation.

In the above-described embodiment, the operating means is the electromagnetic valve 40, but a switching valve that switches the flow path depending on the pressure generated by the servo valve 21 may also be used. This device is designed to direct the tank pressure to the second valve chamber when the handle is not being operated, and to guide the pressure after passing through the throttle to the second valve chamber when the handle is being operated.

<Effects of the Invention> As described above, the present invention is provided with an actuating means for operating the handle, so when the handle is not operated, the pressure fluid from the pump is sucked into the pump without significant pressure loss. Since the water is returned to the boat side, the pump has the advantage of not wasting horsepower.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of a flow rate control device, and FIG. 2 is a sectional view showing a state when a solenoid valve is activated. DESCRIPTION OF SYMBOLS 10... Housing, 11... First valve hole, 12.
...Second valve hole, 13... Throttle passage, 14... Pump, 15... Supply passage, 16... Bypass il! ,
17... Spool valve, 20... Spring, 21...
...Servo valve, 22... Delivery path, 30... Drive circuit, 31... Control circuit, 34... Cylinder device, 40
...Solenoid valve (operating means).

Claims (1)

[Claims] (1) A throttle passage is provided in the middle of the flow path that leads the pressure fluid from the pump to the power steering device, and the opening degree of the bypass passage communicating with the suction port side of the pump is adjusted in response to the differential pressure before and after the throttle passage. In a flow control device for a power steering device, which is provided with a flow rate adjustment spool valve, the flow rate adjustment spool valve is operated to a position where the bypass passage is wide open and the throttle passage is throttled when the steering wheel is not operated. A flow control device for a power steering device, which is provided with an actuating means.