JP3049115B2 - Hydraulic power steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a hydraulic power steering apparatus having a control valve which operates according to a torsion angle of a torsion bar.

[0002]

2. Description of the Related Art An input shaft for steering operation force, an output shaft connected to the input shaft via a torsion bar, a control valve which operates in accordance with a torsion angle of the torsion bar, and a control valve for controlling the input shaft. 2. Description of the Related Art A hydraulic power steering device including a hydraulic actuator that operates by supplied hydraulic oil to apply a steering assist force has been conventionally used.

[0003] In such a hydraulic power steering apparatus, since the straight running stability at the time of high speed running and the reduction of the steering effort at the time of low speed running are required, the torsion bar is twisted when the steering resistance is small. When the rigidity is large and the steering resistance is large, it is desired that the torsion bar has a small torsional rigidity.

[0004] However, the torsional rigidity of the torsion bar is actually constant, and the torsion angle changes in proportion to the torque.
Therefore, a power steering device provided with a vehicle speed sensor and having a regulating means for regulating the torsion of the torsion bar according to the vehicle speed, and a power steering device having a regulating means for regulating the torsion of the torsion bar according to the steering resistance using a spring. There is an apparatus (see Japanese Patent Application Laid-Open No. 61-200063).

[0005]

To control the torsion bar torsion in accordance with the vehicle speed, a vehicle speed sensor and a control device are required, which increases the manufacturing cost.

Further, when the torsion of the torsion bar is restricted by using a spring, there is a problem that the size of the power steering device becomes large because the spring becomes large.

An object of the present invention is to solve the above-mentioned problems of the prior art.

[0008]

A feature of the present invention is that a steering operation force input shaft, an output shaft connected to the input shaft via a torsion bar, and a torsion angle of the torsion bar. A control valve, a hydraulic actuator that operates with pressure oil supplied through the control valve to apply steering assist force, and a fixed throttle provided in a flow path that supplies pressure oil to the control valve. A restricting means for restricting the torsion bar from being twisted by the action of hydraulic pressure on the upstream side of the fixed throttle, and connecting the restricting means with the upstream side of the fixed throttle.
And a releasing means for releasing the action of the hydraulic pressure on the restricting means in the oil flow path by increasing the hydraulic pressure upstream of the fixed throttle.

[0009]

When the vehicle is traveling straight, the torsion angle of the torsion bar is small because the steering resistance is small, and the pressure oil supplied to the control valve is not supplied to the hydraulic actuator that applies the steering assist force. Refluxed to tank. In this state, the hydraulic pressure on the upstream side of the fixed throttle provided in the flow path for supplying the pressure oil to the control valve acts on the regulating means. As a result, the torsion of the torsion bar connecting the input shaft and the output shaft is regulated, and the torsion bar has an increased torsional rigidity.

When the steering angle increases, the torsion angle of the torsion bar increases because the steering resistance increases.
The pressure oil supplied to the control valve is supplied to a hydraulic actuator that applies a steering assist force. Since the pressure of the pressure oil supplied to the hydraulic actuator increases in accordance with the steering resistance, the oil pressure upstream of the fixed throttle also increases. As a result, the action of the hydraulic pressure on the restricting means is released, so that the force for restricting the torsion of the torsion bar does not increase, and the torsional rigidity of the torsion bar is reduced.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

A rack and pinion type hydraulic power steering device 1 shown in FIG. 1 has an input shaft 2 connected to a steering wheel (not shown) of a vehicle, and a torsion bar 6 connected to the input shaft 2.
And an output shaft 3 connected thereto via the The torsion bar 6 is connected to the input shaft via a pin 4 and connected to the output shaft 3 via a serration 5. The input shaft 2 is rotatably supported inside the valve housing 7 via a bearing 8 and inside the output shaft 3 via a bush 12. The output shaft 3 includes bearings 10, 11 inside a rack housing 9. It is rotatably supported via A pinion 15 is formed integrally with the output shaft 3, and steering wheels (not shown) are connected to a rack 16 that meshes with the pinion 15. As a result, the rotation of the input shaft 2 due to the steering operation input is transmitted to the pinion 15 integrated with the output shaft 3 via the torsion bar 6, and the rotation of the pinion 15 causes the rack 16 to move in the vehicle width direction and the vehicle Is steered.

A hydraulic cylinder 20 is provided as a hydraulic actuator for providing an assisting force for the steering operation.
The hydraulic cylinder 20 includes a cylinder tube configured by the rack housing 9 and a piston 21 integrated with the rack 16. In order to supply pressure oil to the oil chambers 22 and 23 in the cylinder tube partitioned by the piston 21 in accordance with the steering direction and the steering resistance, the pressure oil is supplied to the outer periphery of the input shaft 2 according to the torsion angle of the torsion bar 6. A known control valve 30 is provided.

The control valve 30 has a cylindrical valve member 31 surrounding the input shaft 2 inside the valve housing 7. The valve member 31 is connected to the output shaft 3
Are connected so as to rotate together with each other via a pin 32.
The valve housing 17 has an inlet port 34 connected to a pump 33, an outlet port 36 connected to a tank 35, a first port 37 connected to one oil chamber 22 of the hydraulic cylinder 20, And a second port 38 that is connected to the oil chamber 23. Each port 34, 3
6, 37, and 38 communicate with each other through a flow path between the input shaft 2 and the valve member 31, and the flow path is opened by relative rotation between the input shaft 2 and the valve member 31 due to the torsion of the torsion bar 6. Is adjusted. That is, in the straight traveling state, since there is no steering resistance, the twist angle of the torsion bar 6 is 0, the inlet port 34 communicates with the outlet port 36, and the pressure oil supplied from the pump 33 to the control valve 30 is supplied to the tank 35. It recirculates and no pressure oil is supplied to the hydraulic cylinder 20. When the steering is performed and the steering resistance increases, the torsion bar 6 is twisted in accordance with the steering resistance, and the valve member 31 integrated with the output shaft 3 is turned.
Rotates relative to the input shaft 2. Then, entrance port 3
The opening degree of the oil passage between 4 and the outlet port 36 becomes smaller,
From the inlet port 34, the oil chambers 22, 23 of the hydraulic cylinder 20
One of the oil chambers 22 and 23 is supplied with pressurized oil having a pressure corresponding to the steering direction and the steering resistance, and the oil is returned to the tank 35 through the outlet port 36. Thereby, the steering assist force according to the steering direction and the steering resistance is applied to the hydraulic cylinder 20.
Act on the rack 16.

To adjust the engagement between the pinion 15 and the rack 16, a support yoke 40 and a spring 41 are inserted into an insertion hole 9a formed in the rack housing 9, and an adjusting member 42 is screwed into the insertion hole 9a. Has been closed. The support yoke 40 is movable left and right in FIG. 1, and presses the rack 16 against the pinion 15 by the elastic force of the spring 41. The pressing force can be adjusted by adjusting the amount of screwing of the adjusting member 42 into the rack housing 9.

A fixed throttle is provided in a flow path for supplying pressure oil to the control valve 30. In this embodiment, the orifice 50 formed in the valve housing 7 so as to be connected to the inlet port 34 is a fixed throttle . A regulating means 51 is provided for regulating the torsion of the torsion bar 6 by the hydraulic pressure on the upstream side of the orifice 50 acting. This regulating means 51, as shown in FIG.
Four insertion holes 52 are formed in the output shaft 3 along the circumferential direction, and a plunger 53 is inserted into each of the insertion holes 52.
Each plunger 53 is movable along the radial direction of the output shaft 3, and the tip of the plunger 53 is a concave portion 5 formed on the outer periphery of the input shaft 2.
4. A sealing member 55 for sealing the space between the output shaft 3 and the valve housing 7 in an oil-tight manner in the axial direction of the output shaft 3 and at the vertical position of each plunger 53;
An oil chamber 57 is provided between the seal members 55 and 56 in the axial direction. Oil flow paths 58 and 59 for connecting the oil chamber 57 and the upstream side of the orifice 50 via a releasing means 60 described later are formed in the valve housing 7. As a result, the orifice 50
Hydraulic pressure acts on the plunger 53 via the oil chamber 57. Due to the action of the hydraulic pressure, each plunger 53 moves inward in the radial direction of the output shaft 3 to press the input shaft 2 and regulates the relative rotation between the input shaft 2 and the output shaft 3, thereby restricting the torsion of the torsion bar 6. can do.

A release means 60 is provided for releasing the action of the hydraulic pressure on the restricting means 51 by increasing the pressure of the pressure oil supplied to the hydraulic cylinder 20. In this embodiment, a spool chamber 61 is formed between the flow path 58 and the flow path 59,
A spool 62 is movably inserted into the spool chamber 61. In the spool 62, a communication hole 63 that connects the flow path 58 and the flow path 59 is formed. A compression spring 64 that pushes the spool 62 upward in FIG. 1 is provided inside the spool chamber 61. As a result, when the pressure of the hydraulic oil supplied to the hydraulic cylinder 20 increases due to the increase in the steering resistance, the hydraulic pressure on the upstream side of the orifice 50 increases, and the spool 62 moves downward in FIG. Is pushed down. Thereby, the spool 62
Thus, the flow path 58 and the flow path 59 are closed, and the action of the hydraulic pressure on the plunger 53 is released.

The hydraulic power steering apparatus 1 having the above configuration
According to the above, when the vehicle is running straight, the torsion angle of the torsion bar 6 is small because the steering resistance is small, and the pressure oil supplied from the pump 33 to the control valve 30 is not supplied to the hydraulic cylinder 20. Reflux to the tank 35. In this state, the hydraulic pressure on the upstream side of the orifice 50 acts on each plunger 53 of the regulating means 51, so that each plunger 53 presses the input shaft 2 and regulates the relative rotation with the output shaft 3. As a result, the torsion of the torsion bar 6 is restricted, and the torsional rigidity of the torsion bar 6 is increased, so that the steering wheel is not easily steered and the straight running stability at high speed is improved.

When the steering angle increases, the torsion angle of the torsion bar 6 increases because the steering resistance increases, and the pressure oil supplied to the control valve 30 is supplied to one of the oil chambers 22 and 23 of the hydraulic cylinder 20. , An assisting force of the steering operation acts on the rack 16. At this time, the hydraulic pressure acting on the hydraulic cylinder 20 increases according to the steering resistance, so that the pressure on the upstream side of the orifice 50 increases. As a result, the hydraulic pressure acting on the spool 62 of the release means 60 increases, and the spool 62 moves downward in FIG.
Close between. Then, the effect of the hydraulic pressure on the upstream side of the orifice 50 on each plunger 53 of the restricting means 51 is released, so that the force for restricting the torsion of the torsion bar 6 does not increase. As a result, the rigidity of the torsion bar 6 becomes smaller as compared with the case where the steering resistance is small, and the steering effort is reduced.

FIG. 3 shows the relationship between the torsion angle of the torsion bar and the input torque. The solid line A in the figure shows the relationship when the above configuration is adopted, and the broken line B in the figure shows the relationship when the twist is not restricted. Show the relationship. If the torsion is not restricted, the torsion angle of the torsion bar changes in proportion to the input torque. On the other hand, when the above configuration is adopted, in the range where the steering resistance is small and the input torque is small, the increase in the torsion angle with respect to the increase in the input torque is small as compared with the range where the steering resistance is large and the input torque is large, as if the torsional rigidity was low. The relationship changes according to the resistance.

The present invention is not limited to the above embodiment.

For example, as shown in FIG. 4, a ball nut 70 is formed on a ball screw 70 formed integrally with the output shaft 3.
1 is screwed together, a rack 72 is formed on the ball nut 71, and a pitman arm (not shown) is attached to an output shaft 74 integrated with a pinion 73 that meshes with the rack 72. The present invention can also be applied to a hydraulic power steering device that performs the steering operation. The same parts as those of the other embodiments are denoted by the same reference numerals.

The structure shown in FIG. 5 may be adopted as the regulating means 51 '. That is, the levers 2a 'and 2b' are formed so as to project radially outward from the input shaft 2 '.
a 'and 2b' are attached with pins 80 and 81,
A plunger 53 'abutting on 0, 81 is attached to the output shaft 3' so as to be movable in the left-right direction in the figure. This plunger 5
A stopper 82 is attached to the plunger 53 'for restricting the movement of the 3' in the contact direction with the pin 80 by contacting the output shaft 3 '. Then, the hydraulic pressure on the upstream side of the orifice 50 acts on the plunger 53 'via the oil chamber 57'. Thereby, the relative rotation between the input shaft 2 'and the output shaft 3' is restricted by the contact between the pin 80 and the plunger 53 ', and the torsion of the torsion bar 6 is restricted.

In the above embodiment, the control valve has a cylindrical valve member 31 which operates in response to the torsion of the torsion bar 6. However, any control valve which operates in response to the torsion of the torsion bar may be used. For example, as disclosed in Japanese Utility Model Publication No. 63-25271, it may have a plunger-type valve member that moves according to the torsion of the torsion bar.

[0025]

According to the hydraulic power steering apparatus of the present invention, the torsion of the torsion bar can be regulated by the hydraulic pressure according to the steering resistance without using a vehicle speed sensor or a spring. The size can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a steering device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a regulating unit according to the embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a torsion angle of a torsion bar and an input torque;

FIG. 4 is a sectional view of a steering device according to a different embodiment.

FIG. 5 is an explanatory cross-sectional view of a regulating unit according to a different embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Hydraulic power steering device 2 Input shaft 3 Output shaft 6 Torsion bar 20 Hydraulic actuator 30 Control valve 50 Orifice ( fixed throttle ) 51 Restriction means 60 Release means

Claims (1)

(57) [Claims] 1. An input shaft for a steering operation force, an output shaft connected to the input shaft via a torsion bar, a control valve that operates according to a torsion angle of the torsion bar, and a control valve. A hydraulic actuator that operates by the supplied pressure oil to apply a steering assist force, a fixed throttle provided in a flow path for supplying the pressure oil to a control valve thereof, and a hydraulic pressure upstream of the fixed throttle acts. Regulating means for regulating the twist of the torsion bar, and the regulating means and the upstream side of the fixed throttle
And a releasing means for releasing the action of the hydraulic pressure on the restricting means in the oil flow path by increasing the hydraulic pressure upstream of the fixed throttle in the oil flow path .