JPH0143669B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a power steering device.

In general, hydraulic oil is selectively supplied and discharged through a hydraulic servo valve to two working chambers in a cylinder separated by a piston, to assist rotation of a sector shaft connected to the piston, and to connect the sector shaft to the piston. In the case of a power steering device that controls the steering assistance of wheels via a steering link, an input member (for example, a stubshaft) connected to the steered wheels is used to operate the hydraulic servo valve during steering operation. ) and an output member (for example, a sector shaft) that applies steering force to the wheels. That is, when the relative torsional displacement occurs, the hydraulic servo valve is driven, and hydraulic oil is selectively supplied and discharged to the two working chambers, thereby assisting the steering force.

By the way, this steering force assistance, that is, the operation of the power steering device, is only effective when the ground resistance of the wheels is high and a large force is required to rotate the steered wheels, for example, when the vehicle is running at high speed. Since the ground resistance of the wheels is low, operation of the power steering system is not necessary. Therefore, when the operation of the power steering device is not required, the pump that supplies hydraulic oil to the power steering device should also be stopped to reduce the fuel consumption of the vehicle engine that drives this pump. Can be done.

However, in the case of the conventional power steering device, when the supply of hydraulic oil to the power steering device is stopped, the above-mentioned steering force input and relative torsional displacement between the output members are caused by the so-called rotation of the steered wheels. This is manifested as an increase in directional play, and also has the disadvantage of deteriorating steering stability.

The present invention was made in view of the above-mentioned drawbacks, and an object of the present invention is to provide a power steering device that can stop the pump that supplies hydraulic fluid to the power steering device when the power steering device does not need to operate. do. Another object of the present invention is to obtain a power steering device that can ensure steering stability by transmitting the rotational steering force of the steering wheels to the output shaft without any play even when the supply of hydraulic oil is stopped. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a main part of a power steering device showing an embodiment of the present invention. That is, the inside of the cylinder 2 is divided into two working chambers 3 and 4 by the piston 1, and the piston 1 is connected to a sector shaft that drives a control link (not shown), and one end of the cylinder is connected to a sector shaft that drives a control link (not shown). Hydraulic oil is selectively supplied and discharged to the working chambers 3 and 4 through a supply hole 6 and a discharge hole 7 provided in the housing 5 to be sealed, and a sector shaft (not shown) connected to the piston 1 is rotated. The wormshaft 8 passes through the housing 5 under a liquid-tight seal, and has one end screwed into the piston 1, and the other end protrudes into the housing 5 and is connected thereto. It is rotatably supported via a bearing 9. At the other end of the wormshaft 8, a stubshaft 29 is connected to a steering wheel (not shown) and connected to the wormshaft 8 via a torsion bar T.
A servo valve 10 is provided which is driven through a finger pin 30 integral with the working chamber 9 and controls selective communication of the supply hole 6 and the discharge hole 7 with the working chambers 3 and 4. As shown in FIG. 2, this servo valve 10 consists of a servo valve body 11 and a spool 12 that is slidably inserted into the servo valve body 11. Chambers 13, 14, 15 are formed. Valve chamber 1
3 and 14, each of which communicates with an annular groove 5a in the housing 5 in which the supply hole 6 opens.
The supply ports 16 and 17 open, and an oil passage 18 communicating with one of the working chambers 3 is provided in the valve chamber 13.
An oil passage 19 that communicates with the other working chamber 4 is opened in each of the working chambers 4 . Further, the valve chamber 15 is connected to the oil passage A.
When the spool 12 moves to the right or left, the fluid passage area of the valve chamber 13 or the valve chamber 14 relative to the valve chamber 15 increases or decreases, and at the same time the corresponding valve chamber 13 ,1
4, the fluid passage area of the supply ports 16 and 17 is reduced or increased, and the pressure oil from the supply hole 6 is transferred to the working chamber 3 via the oil passage 18 or to the oil passage 1.
9. The oil is selectively guided to the working chamber 4 via the oil passage 5b formed in the housing 5 and the oil passage 2a in the cylinder 2. Further, on the other end side of the wormshaft 8, as also shown in FIG.
0 is provided. To explain this, the control cylinder 20 includes a cylinder body 21, a sealing plate 22 that seals both ends of the cylinder body 21, and a slidable plate 22 disposed mirror-symmetrically within the cylinder body 21.
two pistons 23 and 24, and both pistons 2
3 and 24, each of the sealing plates 22, and springs 25 and 26 interposed between them.
Further, both the pistons 23 and 24 are connected to the spring 2
5, 26 is applied to the snap springs 27, 28.
It is regulated by. A finger pin 30' integrated with the stub shaft 29 is interposed between the pistons 23 and 24 without play, and as in the case of the servo valve 10, rotation of the stub shaft 29 causes one of the pistons 23 and 24 to be moved. spring 2
5 or 26.

Both the pistons 23 and 24 move the cylinder body 2
The piston chambers 31 and 32 separated in the worm shaft 8 are connected to an oil passage 3 formed in the worm shaft 8 as shown in FIG.
5, 36 and an annular oil passage 37, it communicates with an oil passage 38 and a control valve chamber 39. The chamber between the pistons 23 and 24 communicates with the hydraulic oil discharge hole 7 via an oil passage B. Further, the control valve chamber 3
9 communicates with the discharge hole 7 through an oil passage 40. A control valve 41 that opens and closes the oil passage 38 is provided in the control valve chamber 39 . The control valve 41 is actuated by a solenoid 43 against a spring 42 housed in the control valve chamber 39. The solenoid 43 receives a signal from a sensor 44 that detects data such as vehicle speed and steering shaft torque indicating whether or not to operate as power steering, and is turned on and off by the control output thereof.

46 is an electromagnetic clutch 48 connected to the engine 47 of the vehicle.
The oil pump 46 can be stopped by disconnecting the electromagnetic clutch 48 using the output of the controller 45.

In such a configuration, when the stub shaft 29 is rotated clockwise or counterclockwise using a steering wheel (not shown), the worm shaft 8 connected to the stub shaft 29 via the torsion bar T also attempts to rotate. However, at the initial stage of rotation, the sector shaft (not shown) receives ground resistance from the wheels via the steering link, so the piston 1 and the wormshaft 8 are stationary, and there is a relative gap between the piston 1 and the stub shaft 29. Causes torsional displacement. Thus, a finger pin 30' integral with the stub shaft 29 moves one of the pistons 23, 24 of the control cylinder 20. At this time, the control valve 41 is in the position shown in FIG.
Because it communicates with the oil passage 40 that communicates with the through hole 3
3, 34, oil passages 35, 36, and annular oil passage 37, and further through oil passages 38, 40, it easily flows from the discharge hole 7 to a reservoir tank (not shown). Therefore,
The pistons 23 and 24 can be easily moved along with the rotation of the stub shaft 29 without interfering with the rotation. In this way, the stub shaft 29 is rotatable, and the servo valve 10 is driven by the finger pin 30 integral with the stub shaft 29, selectively supplying and discharging hydraulic fluid to and from the working chambers 3 and 4, and operating the control link. The steering assistance operation of the wheels is performed through the steering wheel.

On the other hand, when the power steering system does not need to operate, such as when the vehicle is running at high speed, when the vehicle speed reaches a desired set speed, the sensor 44 detects this and the controller 45 uses the output to activate the electromagnetic clutch 48. A disconnection signal is output to the solenoid 43 to stop the operation of the oil pump, and at the same time, current is applied to the solenoid 43. Therefore, the control valve 41 slides in the control valve chamber 39 against the spring 42 and closes the oil passage 38. Therefore, the hydraulic oil in the piston chambers 31 and 32, together with the hydraulic oil in the through holes 33 and 34, the oil passages 35 and 36, and the annular oil passage 37, is prevented from flowing into and out of the oil passage 40. Thus, the pistons 23 and 24 of the control cylinder 20 are restricted in their movement and are in a locked state, so that the stub shaft 29
The deflection of the finger pin 30 is also regulated. That is, the rotational movement of the stub shaft 29 is directly transmitted to the worm shaft 8 without any play.

As a result, when in such a condition, the pump 46
Even if the supply of hydraulic oil to the steering device is stopped, no relative torsional displacement occurs between the input and output members of the steering force.
Therefore, the problem of increased play in the rotational direction of the steering wheels does not occur, and the steering stability during high-speed running, similar to that of a normal manual gear-coupled steering system, is ensured.

The pistons 23 and 24 are locked in such a way that when the hydraulic pressure of the pump 46 decreases for some reason or when the pump 46 stops, the controller 45 detects this and closes the control valve 41. It is also possible to do so.

In this way, when power steering operation is not required, even if the pump is stopped, the desired stable steering is possible, contributing to the fuel efficiency of the vehicle. Note that the control valve 41 only needs to be disposed between the control cylinder 20 and the oil storage tank communicating with the discharge hole 7;
It is not an essential requirement to provide it at a desired position.

As explained above, according to the present invention, the wormshaft includes a control cylinder in which a through hole communicating with a hydraulic oil discharge hole is opened, and a connection between the through hole and the hydraulic oil discharge hole that are open in the control cylinder. and a control valve that is provided between the cylinders and operates to prevent communication between them when the oil pump that supplies hydraulic oil is stopped, and prevents the hydraulic oil from flowing out and flowing into the cylinder. By integrating the stub shaft and worm shaft related to the control piston, it is possible to input steering force and transmit it between output members without any play, thereby ensuring steering stability and driving the oil pump. A power steering device capable of reducing engine fuel consumption is obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part showing the power steering device of the present invention, FIG. 2 is a sectional view taken along line A-A in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG. 1. It is a diagram. 1... Piston, 2... Cylinder, 3, 4...
Working chamber, 5...housing, 6...supply hole, 7...
...Discharge hole, 8... Wormshaft, 10... Servo valve, 16, 17, 18, 19... Oil path, 20
... Control cylinder, 21 ... Cylinder body, 2
3, 24... control piston, 29... stub shaft, 33, 34... through hole, 41... control valve,
A, B...Oil road.

Claims (1)

[Claims] 1. In a power steering device that selectively supplies and discharges hydraulic oil to two working chambers in a cylinder separated by a piston and assists rotation of a sector shaft connected to the piston, one end is screwed to the piston. a wormshaft comprising an oil passage communicating with each of the two working chambers and an oil passage communicating with each of the hydraulic oil supply hole or discharge hole;
A servo valve is disposed on the wormshaft and controls selective communication between an oil passage communicating with each of the two working chambers and an oil passage communicating with each of the hydraulic oil supply hole or discharge hole. Two piston chambers are separated by two slidable control pistons provided in the wormshaft and mirror-symmetrically disposed inside the wormshaft and a sealing plate sealing both ends. A control cylinder is provided with a through hole communicating with a hydraulic oil discharge hole, and a hydraulic oil discharge hole or an oil storage tank is provided between the control cylinder and the hydraulic oil discharge hole or an oil storage tank. When the oil pump stops,
The stub shaft, which is connected to the steering wheel, is rotated clockwise or counterclockwise.
A power steering device configured to be able to actuate the servo valve and at the same time to be able to selectively actuate either one of the two control pistons in the control cylinder.