JPH0133422Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a power steering device that uses hydraulic pressure to reduce the steering force of a vehicle, and more specifically, when the speed of the vehicle or engine increases to a certain extent, the control valve moves in response to the steering wheel operation. The present invention relates to a speed-sensitive power steering device that stops power assist by restricting speed.

A power steering device, typified by a power steering device for an automobile, generally provides selective control to an output drive unit connected to the wheels (steering mechanism) via a control valve that switches based on input rotation from a steering wheel. By supplying pressurized oil, the steering force is reduced.

By the way, as the running speed of the vehicle increases, the resistance force generated between the wheels and the road surface when operating the steering wheel becomes smaller, and the pump oil pressure has a property of increasing in proportion to the engine rotation speed. There was a problem in that the power assist force for steering wheel operation sometimes became excessive, impairing the steering stability of the steering wheel.

Therefore, the present applicant filed Japanese Patent Application No. 57-161415,
We are proposing a power steering device equipped with a spool-type control valve that improves high-speed stability. This apparatus will be explained below based on FIGS. 1 and 2.

The device main body is composed of a planetary gear device 2, a control valve 3, and an output drive section (power cylinder) 1. First, the planetary gear device 2 includes three planetary gears 4 to 4 supported by a carrier (input shaft) 7 connected to a handle H, a sun gear 5 meshing with the three planetary gears 4, and a ring gear 6.
The sun gear 5 is connected to the output drive section 1, and a groove 8 is formed on the outer periphery of the ring gear 6. A pin 9 is inserted into the groove 8 in the radial direction.
The end portion of the control valve 3 projects into the lumen 13 of the control valve 3, which will be described later.

Next, the control valve 3 is housed in the valve hole 10 , and a spool 12 is housed inside the sleeve 11 fixed to the valve hole 10 so as to be slidable in the axial direction. It is formed short, and the end of a pin 9 that fits into the groove 8 of the ring gear 6 and penetrates the side wall of the spool 12 protrudes from the inner cavity 13 thereof.

There are two annular grooves 1 on the outer peripheral surface of this spool 12.
4 and 15 are formed, and three annular grooves 16 to 18 are formed on the inner circumferential surface of the sleeve 11, among which the central annular groove 17 communicates with the hydraulic pump P via a passage 19, and the left and right annular grooves The annular grooves 16, 18 communicate with a tank 21 via a passage 20.

In addition, passages (not shown) that communicate with the pressure chambers 1A and 1B of the output drive section 1 are opened in the inner circumferential surface of the sleeve 11, located at the annular grooves 14 and 15 formed in the valve spool 12, respectively. and form an actuation port. Additionally, means are provided to maintain the spool 12 in a neutral position so that it cannot be switched when the vehicle or engine speed (hereinafter simply referred to as "speed") increases.

This means includes connectors 22, 22 that close both side openings of the valve hole 10, and connectors 22, 22 that contact both end surfaces of the sleeve 11 in the neutral state.
Valve seats 25 and 25 define reaction oil chambers 23 and 24 between them, and are interposed between the valve seat 25 and the connector 22 and urge the valve seat 25 to be crimped onto the sleeve 11. spring 2
6, 26 and a circuit 27 that communicates with both reaction oil chambers 23, 24, and a part of the pump P (such as a passage that leads back pressure to the vane base of the vane pump).
A solenoid valve 28 is installed in a circuit 32 that communicates with the circuit 32 to open and close the circuit 32, and a control device (for example, a control device that drives the solenoid valve 28 in the direction of opening the solenoid valve 28 while the speed is equal to or higher than a predetermined value) It consists of a comparator 30 that compares the signal with a set value and outputs a drive signal to the electromagnetic valve.

The electromagnetic valve 28 includes a valve 28a and an electromagnetic solenoid 28b. A spool 34 is housed in the valve hole 33 of the valve 28a so as to be slidable in the axial direction. An annular groove 3 is formed on the outer peripheral surface of this spool 34.
5 is formed, and 3 is formed on the inner peripheral surface of the valve hole 33.
Two annular grooves 36 to 38 are formed, of which the right (as shown) and center annular grooves 36 and 37 are formed.
A portion of the hydraulic pump P and both reaction force oil chambers 2 are connected via portions 32a and 32b of the circuit 32, respectively.
The base 33a on the left side (illustrated) of the valve hole 33 communicates with the circuit 27 that communicates the valve holes 33 and 24.
communicates with tank 21 via circuit 39.

The electromagnetic valve 28 normally closes communication between the circuits 32a and 32b, as shown in the figure, and closes the communication between the circuits 32a and 32b.
2b, annular groove 37, 35, 38, valve hole base 3
Both reaction force oil chambers 23 and 24 are communicated with the tank 21 by a circuit 27 via a circuit 3a and a circuit 39, but when the electromagnetic solenoid 28b is actuated by the output signal of the control device 30 and pushes out the spool 34, the circuit 32b and the circuit 39, and the circuit 3 through the annular grooves 36, 35 and 37.
2a is connected to the circuit 32b, and the hydraulic pressure generated by the hydraulic pump P is sent to the both reaction force oil chambers 2 through the circuits 32 and 27.
It is designed to lead to both numbers 3 and 24.

The effects based on the above configuration are as follows.

First, to explain the normal power steering action when the speed is below a predetermined value, if you turn the handle H and rotate the planet gears 4 to 4 via the carrier 7 that communicates with it, the output drive unit 1 and the sun gear 5 connected thereto are in a pseudo-fixed state based on ground resistance, the ring gear 6 rotates, and the spool 12 is moved, for example, to the right via the pin 9 that fits into the groove 8 of the ring gear 6. Displace.

At this time, the reaction oil chamber 24 is connected to the tank 2 through the circuits 27 and 32a, the electromagnetic valve 28, and the circuit 39.
1, the spool 12 contracts the oil chamber 24 and freely moves to the right.

Then, until now, the passage 19, the annular groove 17, 1
The pressure oil from the pump that was circulating to the tank 21 through the passages 20 and 4, 16 is switched by the rightward movement of the spool 12, and the pressure is returned to one pressure chamber 1A of the output drive unit 1 through a passage (not shown). Oil is fed into the pressure chamber 1B, and the other pressure chamber 1B communicates with the passage 20 through a passage (not shown) and becomes a low-pressure side, so that the output drive unit 1 turns the wheels.

When the handle H is turned in the opposite direction to the above, the spool 12 moves to the left, and the output drive unit 1 turns the wheels in the opposite direction. In this way, the steering force is reduced in low speed ranges where the ground resistance of the wheels is large.

On the other hand, if the speed increases and exceeds a predetermined value, the electromagnetic solenoid 28b drives the spool 34 toward the tip based on a command from the control device 30, closes the circuit 39, and closes the annular groove 36,
35 and 37, and the pressure generated by the hydraulic pump P (vane back pressure of the vane pump) is guided to the reaction oil chambers 23 and 24 through the circuit 27, so that in the neutral position, the valve seat 25 ,25
are pressed against both end surfaces of the sleeve 11 by this hydraulic pressure. This restricts the axial displacement of the spool 12, and therefore the ring gear 6 is fixed via the pin 9. As a result, the sun gear 5 rotates as the handle is operated, and the output actuator 1 can be operated manually. Operate.

However, since the hydraulic pump P is driven to rotate the engine via a V-belt or the like, it is installed in a position close to the engine, while the planetary gear device 2 is installed connected to the steering shaft, and the electromagnetic valve 28 is connected to the planetary gear. Since it is installed in a position close to the device 2, it is responsible for the circuits 19 and 32a connected to the hydraulic pump P.
The problem was that the hydraulic piping in this case was long, leading to complications in the piping.

Note that if the rotation 32a is branched from the middle of the circuit 19, the passage length can be shortened, but in this case, while the control valve is in the neutral state and the pump port is connected to the tank port side, the pump discharge pressure is almost equal to the tank pressure. Therefore, even if this pressure is introduced into the pressure oil chambers 23 and 24, a predetermined hydraulic reaction force cannot be obtained when the control valve 3 is in the neutral state and at the initial stage of switching. Of course, if the control valve 3 is switched and the pump discharge pressure increases in accordance with the operating load of the power cylinder 1, the pressure in the reaction oil chamber 23 or 24 will increase accordingly, but at high speeds where the steering resistance is extremely small. When driving, it is necessary to generate a hydraulic reaction force even in the neutral state in order to suppress the wobbling of the steering wheel and improve steering stability.Also, due to the delay in response at the initial stage of switching of the control valve 3, it is necessary to generate a hydraulic reaction force suddenly after starting to turn the steering wheel. It is also undesirable from the viewpoint of steering feeling that the hydraulic reaction force becomes large.

Therefore, it was necessary to introduce hydraulic pressure into the circuit 32a not from the normal pump discharge pressure, but from a portion that always has a pressure equal to or higher than a predetermined value (a value at which a predetermined hydraulic reaction force can be obtained). For this reason, the back pressure led to the vane base end of the vane pump is removed from the circuit 32.
This was used as the introduction pressure for a, resulting in the above-mentioned problem.

The present invention was developed by focusing on the above-mentioned problem.The entire amount of hydraulic oil from the hydraulic pump is sent to the control valve via the electromagnetic valve.During high-speed driving, a throttle passage is formed as the electromagnetic valve switches. The purpose of this invention is to simplify the hydraulic pump discharge passage by communicating with the pump port of the control valve through the hydraulic pressure chamber and introducing pressure generated on the upstream side of the restriction passage into the reaction oil chamber.

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that the same components as those of the conventional example shown in FIGS. 1 and 2 are given the same reference numerals.

As shown in FIG. 3, the electromagnetic valve 51 consists of a valve 51a and an electromagnetic solenoid 51b, and a spool 53 is housed in the valve hole 52 of the valve 51a so as to freely slide in the axial direction. This spool 53
Annular grooves 54 and 55 are formed on the outer peripheral surface of the valve 52, and annular grooves 56 to 58 are formed on the inner peripheral surface of the valve 52, of which the right annular groove 56 (as shown) is controlled via a circuit 60. It communicates with the pump port 62 of the valve 3, the central annular groove 57 communicates with the hydraulic pump P via the circuit 32a, and the annular groove 58 communicates with the circuit 32b.
The valve hole 52 is connected to both reaction force oil chambers 23 and 24 of the control valve 3 via a circuit 27, and a base 52a on the left side (as shown) of the valve hole 52 is connected to the tank 21 via a circuit 39.

The inner diameter of the annular convex portion 60 defining the annular grooves 56 and 57 is formed to be slightly larger than the outer diameter of the spool 53. In other words, as shown in FIG. 4, the electromagnetic solenoid 51b drives the spool 53 toward the tip.
When the outer circumferential surface of the spool 53 and the annular convex portion 60 face each other, the inner circumferential surface of the annular convex portion 60 and the outer circumferential surface of the spool 53 form a throttle passage 61 having an annular cross-sectional shape.

First, when the speed is below a predetermined value, the spool 53 of the electromagnetic valve 51 is located on the left side as shown in FIG.
6. The hydraulic pressure generated by the hydraulic pump P is guided to the pump port 62 of the control valve 3 via the circuit 63, while the circuit 39, the annular grooves 54 and 58, and the circuits 32b and 27
Both reaction force oil chambers 23 and 24 are connected to tank 2 through
Connects to 1. In this state, the spool 12 of the control valve 3 is linked to the rotation of the handle H,
It is possible to move left and right while expanding and contracting the reaction oil chambers 23 and 24, and the pressure oil from the hydraulic pump P is transmitted through the circuit 32a, the electromagnetic valve 51, the circuit 63, the control valve 3, and a circuit (not shown). It is sent to the output drive unit 1, and the steering force is reduced.

In this case, since almost no resistance is applied to the hydraulic oil passing through the electromagnetic valve 51, there is no throttling loss, and the output drive unit 1 also uses this pressure oil to maintain a predetermined power assist force mainly in the low-speed driving range. demonstrate.

On the other hand, the speed increases and exceeds the predetermined value,
When the electromagnetic solenoid 51b drives the spool 53 toward the distal end based on a command from the control device 30 (see FIG. 4), the circuit 39 closes and the circuit 32a, the annular grooves 57, 54, 58, the circuit 32b,
27 to the hydraulic pump P and both reaction force oil chambers 23, 2.
On the other hand, the pump port 62 of the control valve 3 also maintains communication with the hydraulic pump P via the circuit 32a, the annular groove 57, the throttle passage 61, the annular groove 56, and the circuit 63.

Here, the throttle passage 11 reduces the flow cross-sectional area, provides resistance in the fluid passage communicating with the pump port 62 of the control valve 3, and creates resistance in the fluid passage upstream of the throttle passage 61 (hydraulic pump P side). increase the pressure. Since this oil pressure is guided to both reaction force oil chambers 23 and 24, the valve seats 25 and 25 press both end surfaces of the spool 12 in accordance with the oil pressure. As a result, the axial displacement of the spool 12 is restrained, the control valve 3 is not switched, and the output actuating section 1 is operated manually by operating the handle, improving steering stability during high-speed driving.

As described above, the present invention communicates the hydraulic pump and the pump port of the control valve through the electromagnetic valve, and also communicates directly through the throttle passage during high-speed running, and at this time, the upstream pressure of the throttle passage is controlled by the control valve. Since the hydraulic pressure is guided to the reaction oil chamber, the hydraulic piping connected to the pump port can be shortened, and the hydraulic pump discharge passage can be simplified.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a conventional example, and the second
The figure is a sectional view of the valve when it is in neutral. FIG. 3 is a sectional view showing an embodiment of the present invention, and FIG. 4 is a sectional view of the electromagnetic valve shown in the same figure during switching operation. 1... Output drive unit, 3... Control valve, 12...
... Spool, 21 ... Tank, 23, 24 ... Reaction oil chamber, 51 ... Solenoid valve, 52 ... Valve hole, 53 ... Spool, 61 ... Throttle passage, 62
...Pump port, P...Hydraulic pump.

Claims (1)

[Scope of utility model registration request] A spool-type control valve that switches based on input rotation from the handle, two reaction oil chambers separated at both ends of the spool of this control valve, and a circuit that leads hydraulic pressure to these reaction oil chambers. In the power steering device, the electromagnetic valve is configured to selectively supply pressurized oil to an output drive unit connected to the wheels via the control valve, and the electromagnetic valve is configured to control the control valve according to the speed of the vehicle or the engine. When the speed is below a predetermined value, the pump port of the control valve is connected to the discharge circuit of the hydraulic pump, and at the same time, the circuit that connects directly to the reaction oil chamber is connected to the tank port. However, when the speed is above a predetermined value, the pump port is formed to communicate with the discharge circuit of the hydraulic pump through the throttle passage, and at the same time, the upstream side of the curving passage is communicated with the reaction oil chamber. A power steering device characterized by: