JP2556278Y2 - 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 A conventional hydraulic power steering apparatus 101 shown in FIG. 10 includes an input shaft 102 for steering operation force and an output shaft 104 connected to the input shaft 102 via a torsion bar 103. A pinion 105 is integrated with the output shaft 104, and a rack 106 meshes with the pinion 105, and a steering wheel (not shown) interlocks with the rack 106. As a result, the rotation of the input shaft 102 is transmitted to the pinion 105 via the torsion bar 103, and the rack 10 is rotated by the rotation of the pinion 105.
The steering wheel is steered by the movement in the vehicle width direction 6.

A hydraulic cylinder 107 for applying an assisting force for the steering operation is connected to the rack 106. Hydraulic cylinder 107 is supplied with pressure oil by pump 109 to tank 1.
08 through the control valve 110. The control valve 110 supplies pressurized oil to the hydraulic cylinder 107 according to the torsion angle of the torsion bar 103 according to the steering resistance and the steering direction, whereby the hydraulic cylinder 107 applies a steering assist force to the rack 106.

[0004] Such a hydraulic power steering device 1
In the case of 01, since straight running stability at the time of high-speed running and reduction of steering effort at the time of low-speed running are required,
When the steering resistance is small, it is desired that the torsional bar 103 has a large torsional rigidity, and when the steering resistance is large, it is desired that the torsional bar has a small torsional rigidity. for that reason,
A regulating means 111 for regulating the torsion of the torsion bar 103 by the action of the hydraulic pressure, and a hydraulic pressure adjusting valve 112 acting on the regulating means 111 are provided.

The control valve 112 is connected to the housing 11
An orifice 116 is provided which has a pair of spools 114 and 115 inserted into the inside 3 and which opens and closes by the relative movement of both spools 114 and 115. Through the orifice 116, the pressure of the pressure oil supplied from the pump 109 acts on the plunger 117 of the regulating means 111. The plunger 117 is inserted into the output shaft 104 and presses the input shaft 102 by the action of hydraulic pressure to regulate the relative rotation between the input shaft 102 and the output shaft 104, thereby regulating the torsion of the torsion bar 103.

When the hydraulic pressure acting on the regulating means 111 increases through the orifice 116, the spool 114 moves upward in the drawing to close the orifice 116 and is pushed by a spring 118 in a direction to open the orifice 116. I have.

The other spool 115 has a solenoid 119
The current acting on the solenoid 119 is controlled by a controller 121 having a vehicle speed sensor. As a result, the other spool 115 moves downward in the figure due to a decrease in vehicle speed and closes the orifice 116, and moves upward in the figure to open the orifice 116 as the vehicle speed increases.

The above-mentioned conventional hydraulic power steering device 1
According to No. 01, in the straight running state, the pressure of the oil sent from the pump 109 acts on the plunger 117 of the regulating means 111 via the orifice 116, and the torsion bar 1
Since the twist of 03 is regulated, the straight running stability is improved. When steering is performed, the steering resistance increases, the torsion bar 103 is twisted, and the pressure of the pressure oil supplied to the hydraulic cylinder 107 increases, so that the hydraulic pressure acting on the regulating means 111 also increases. Thereby, one spool 114
Moves in the direction to close the orifice 116, and the restricting means 1
Since the action of the hydraulic pressure on the plunger 117 of the eleventh is cancelled, the torsion bar 103 is released from the twisting control, and the steering effort is reduced.

The other spool 115 moves in a direction to close the orifice 116 as the vehicle speed decreases and moves in a direction to open the orifice 116 as the vehicle speed increases. Therefore, as shown in FIG. The value of the input torque required to increase the increase rate of the vehicle increases as the vehicle speed increases. That is, the straight running stability is good at a high speed, and the steering effort is reduced at a low speed. this is,
When the vehicle speed increases, the opening of the orifice 116 increases due to the movement of the other spool 115, so that the distance that one spool 114 has to move to close the orifice 116 increases. That is, the moving distance of one of the spools 114 does not increase unless the steering resistance increases and the hydraulic pressure acting on the restricting means increases, so that as the vehicle speed increases, the input torque value increases against the large steering resistance. It depends on what has to be bigger.

[0010]

In the conventional hydraulic power steering apparatus 101, one end of a spring 118 for pushing one spool 114 of the control valve 112 in the opening direction of the orifice 116 is supported by one spool 114. Since the other end is supported by the cap 122 fitted into the housing 113, the elastic force of the spring 118 cannot be adjusted. Therefore, the elastic force of the spring 118 pressing the spool 114 changes depending on the dimensional accuracy of the members constituting the adjustment valve 112, and there is a problem that desired steering characteristics cannot be obtained. In particular, when the change of the steering force with respect to the speed change is made larger in the low speed region than in the high speed region, one of the spools 114 is used.
Is used as the spring 118 which presses the spring, the relationship between the load and the deflection becomes non-linear. However, since the magnitude of the initial load which affects the non-linear characteristic of the spring 118 cannot be adjusted, the desired steering characteristic is not adjusted. It was difficult to obtain.

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

[0012]

The present invention is characterized in that an input shaft for steering operation force, an output shaft connected to the input shaft via a torsion bar, and a torsion angle of the torsion bar. and a control valve which operates Te, pop
A hydraulic actuator which applies a steering assist force actuated by a hydraulic fluid supplied through the control valve from the flop,
A regulating means for regulating the torsion bar torsion by the action of hydraulic pressure, and a hydraulic pressure adjusting valve acting on the regulating means, the regulating valve having a pair of spools inserted into the housing, One spool
Is axially movable inside the housing,
Spool can move axially relative to one spool
It is a pump and regulations by the axial relative movement of both spools
Orifice for opening and closing the space between the control means, con from the pump
The pressure of the oil flowing into the troll valve causes this orifice
Through one of the spurs
The housing in the direction to open the orifice by elastic force.
A spring that moves axially with respect to the
The spring is large in the area where the applied load is small.
Non-linearity with large deflection change to applied load compared to domain
One of the spools is provided with a regulating means.
In the direction to close the orifice by increasing the hydraulic pressure acting on the
It is axially movable with respect to the housing, and the other
To the other spool due to a decrease in vehicle speed.
Move the orifice in the axial direction to close the orifice and
Hand that moves axially in the direction to open the orifice by increasing
In a hydraulic power steering apparatus in which a step is attached to a housing, the elastic force of the spring is adjustable from outside the housing, and the spring is
Move one spool in the direction to close the orifice
The load in the state before the action of the hydraulic pressure is set to substantially zero.

[0013]

According to the structure of the present invention, the elastic force of the spring for pushing one spool of the adjusting valve in the opening direction of the orifice can be adjusted from the outside of the housing, so that the dimensional accuracy of the parts constituting the adjusting valve can be adjusted. Regardless, one of the spools can be pushed with a desired elastic force. Also, you have use a nonlinear characteristic spring as a spring pressing the one of the spool, an initial applied load of the spring, i.e. one in response to a steering input
To move the spool in the direction to close the orifice
The applied load in a state before the operation of the hydraulic pressure can be adjusted.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

A rack and pinion type hydraulic power steering apparatus 1 shown in FIG. 1 has an input shaft 2 connected to a steering wheel (not shown) of a vehicle, and a torsion bar 3 connected to the input shaft 2.
And an output shaft 4 connected thereto. The torsion bar 3 is connected to the input shaft 2 via a pin 5 and to the output shaft 4 via a serration 6. Its input shaft 2
Is rotatably supported via a bearing 15 while being inserted into the valve housing 7 via a seal member 8 and further rotatably supported on the inner periphery of the output shaft 4 via a bearing 9. The output shaft 4 is rotatably supported inside the rack housing 10 via bearings 11 and 12, and a pinion 13 is integrated with the output shaft 4. Steering wheels (not shown) are connected to a rack 14 that meshes with the pinion 13. As a result, the rotation of the input shaft 2 due to the steering operation input is transmitted to the pinion 13 integrated with the output shaft 4 via the torsion bar 3, and the rotation of the pinion 13 causes the rack 14 to move in the width direction of 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 10 and a piston 21 integrated with the rack 14. Oil chambers 22, 23 in a cylinder tube partitioned by the piston 21
In order to supply pressure oil according to the steering direction and steering resistance,
A known control valve 30 that operates according to the torsion angle of the torsion bar 3 is provided.

The control valve 30 has a cylindrical valve member 31 surrounding the input shaft 2 inside the valve housing 7. This valve member 31 is connected to the output shaft 4.
Are connected so as to rotate together. The valve housing 7 has an inlet port 34 connected to a pump 33.
, An outlet port 36 connected to the tank 35, a first port 37 connected to one oil chamber 22 of the hydraulic cylinder 20, and a second port 38 connected to the other oil chamber 23.
And The ports 34, 36, 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 rotated relative to the input shaft 2 and the valve member 31 by the torsion of the torsion bar 3. Adjusts the opening. That is,
In the straight traveling state, the torsion bar 3 has a twist angle of 0 because there is no steering resistance, and the entrance port 34 and the exit port 36
And the pressure oil supplied from the pump 33 to the control valve 30 is returned to the tank 35 and the hydraulic cylinder 2
No pressure oil is supplied at zero. When steering is performed and the steering resistance increases, the torsion bar 3 is twisted according to the steering resistance, and the valve member 31 integrated with the output shaft 4 rotates relative to the input shaft 2. Then, the degree of opening of the flow path between the inlet port 34 and the outlet port 36 decreases, and the pressure oil having a pressure corresponding to the steering direction and the steering resistance is supplied from the inlet port 34 to one of the oil chambers 22 and 23 of the hydraulic cylinder 20. And oil chamber 2
Oil flows from the other one of the outlets 23 to the tank 35 through the outlet port 36. As a result, a steering assist force according to the steering direction and the steering resistance acts on the rack 14 from the hydraulic cylinder 20.

A regulating means 51 for regulating the torsion of the torsion bar 3 by the action of the pressure of the oil sent from the pump 33 is provided. This regulating means 51
As shown in FIG. 2, four insertion holes 52 are formed in the output shaft 4 along the circumferential direction, and each of the insertion holes 52 has a plunger 5.
3 is inserted. Each plunger 53 is movable along the radial direction of the output shaft 4, and its tip is in contact with a concave portion 54 formed on the outer periphery of the input shaft 2. In the vertical direction of each plunger 53 in the axial direction of the output shaft 4,
Seal members 55 and 56 for sealing the space between the output shaft 4 and the valve housing 7 in an oil-tight manner are attached to the output shaft 4,
Thereby, the space between the seal members 55 and 56 in the axial direction is
7 is set. An oil flow path 59 connecting the oil chamber 57 and the inlet port 34 via an adjustment valve 60 described later is formed in the valve housing 7. Thereby, when the hydraulic pressure acts on each plunger 53 via the oil chamber 57,
Each plunger 53 moves inward in the radial direction of the output shaft 4 to press the input shaft 2 and regulates the relative rotation between the input shaft 2 and the output shaft 4, so that the torsion of the torsion bar 3 can be regulated.

An oil pressure adjusting valve 60 acting on the regulating means 51 is provided inside the valve housing 7. The adjustment valve 60 has a first spool 61 and a second spool 62 inserted into the valve housing 7. The two spools 61 and 62 are cylindrical, and the second spool 62 is inserted into the first spool 61 so as to be relatively movable in the axial direction.
Is inserted movably in the axial direction.

As shown in FIGS. 3 to 5, the axial relative movement of the two spools 61, 62 between the step 61a on the inner periphery of the first spool 61 and the convex portion 62a on the outer periphery of the second spool 62. An orifice 63 is opened and closed by the orifice. The diameter of the convex portion 62a increases as going upward in the figure,
Thus, the first spool 61 moves upward in the figure to close the orifice 63, and the second spool 62 moves downward in the figure to close the orifice 63. A through hole 64 is provided in the first spool 61 for communicating the upstream side (upper side in the figure) of the orifice 63 with the inlet port 34, and the downstream side (lower side in the figure) of the orifice 63 and the regulating means. The first spool 61 is provided with a through hole 65 that communicates with a flow path 59 that communicates with the oil chamber 57 of the first spool 61. This allows the pump 33 to move from the inlet port 34
Of the oil flowing into the control valve 30 through the orifice 63
Act on.

The first spool 61 moves in a direction to close the orifice 63 due to an increase in hydraulic pressure acting on the regulating means 51. That is, a step surface 66 is formed on the outer periphery of the first spool 61, and the hydraulic pressure acting on the regulating means 51 acts on the step surface 66, whereby the first spool 61 moves upward in the figure to move the orifice 63. close.

The first spool 61 is moved downward in the figure, that is, in the direction in which the orifice 63 is opened, by the elastic force of the spring 67. The spring 67 is a compression coil spring that is elastically deformed in the vertical direction in the figure. One end is supported by the upper surface of the first spool 61, and the other end is supported by the inner surface of the cap 68. A male screw 68 a is formed on the outer periphery of the cap 68 and screwed into a female screw hole 7 a formed in the valve housing 7. Also, the cap 68
A lock nut 69 is screwed into the external thread 68a on the outer periphery of the lock nut 69. Further, a hexagonal hole 68b for inserting a tool is formed in an upper portion of the cap 68 as shown in FIG. Thus, when the screwing amount of the cap 68 into the female screw hole 7a is increased, the elastic force of the spring 67 pressing the first spool 61 increases, and when the screwing amount is reduced, the elastic force of the spring 67 pressing the first spool 61 increases. Become smaller. The outer periphery of the cap 68 and the valve housing 7
A seal member 70 is interposed between the seal member 70 and the inner circumference.

The second spool 62 moves downward in the figure, that is, in the direction to close the orifice, as the vehicle speed decreases, and moves upward in the figure, that is, in the direction to open the orifice 63, as the vehicle speed increases. For this purpose, a solenoid 71 is attached to the lower part of the valve housing 7, and this solenoid 71 is connected to a known controller 72 having a vehicle speed sensor. Thus, the current applied to the solenoid 71 changes according to the vehicle speed, and the larger the vehicle speed, the larger the current applied. This solenoid 7
A base 74 and a slider 73 made of a magnetic material are arranged inside the unit 1. The lower part of the slider 73 is the base 7
4 is vertically movably inserted into the second spool 6.
2 and a nut 75 is screwed to the upper end. The second spool 62 is sandwiched between the nut 75 and the step 74 a formed on the slider 74, whereby the second spool 62 moves along with the slider 74. A spring (not shown) for pushing the slider 74 upward in the figure.
Is provided.

The hydraulic power steering apparatus 1 having the above configuration
According to FIG. 3, in the high-speed straight traveling state, as shown in FIG.
Since the spool 62 moves upward to open the orifice 63, the pressure of the oil sent from the pump 33 acts on the plunger 53 of the regulating means 51 via the orifice 63. Thereby, since the torsion of the torsion bar 3 is regulated, the straight running stability is improved. When the steering is performed, the steering resistance increases, the torsion bar 3 is twisted, and the pressure of the pressure oil supplied to the hydraulic cylinder 20 increases.
The hydraulic pressure acting on the plunger 53 of the regulating means 51 increases. Due to the increase in the hydraulic pressure, the first spool 61 moves upward to close the orifice 63 as shown in FIG.
The action of the hydraulic pressure on the plunger 53 of the regulating means 51 is released. As a result, the twisting of the torsion bar 3 is released, so that the steering effort is reduced.

When the vehicle speed increases, the opening of the orifice 63 increases due to the movement of the second spool 62 as shown in FIG. 3, so that the distance that the first spool 61 must move to close the orifice 63 is large. Become.
When the vehicle speed decreases, as shown in FIG.
Since the opening of the orifice 63 is reduced by the movement of 2, the distance that the first spool 61 has to move to close the orifice 63 is reduced. The moving distance of the first spool 61 does not increase unless the hydraulic pressure acting on the plunger 53 of the regulating means 51 increases due to an increase in the steering resistance. Therefore, as the vehicle speed increases, the input torque is reduced against the large steering resistance. Must be bigger. As a result, a reduction in steering effort at low speeds and an improvement in straight running stability at high speeds are achieved.

As shown in FIG. 7, the spring 67 in this embodiment has a smaller load in a region where the load is small than in a region where the load is large.
It is said to have non-linear characteristics with a large deflection change with respect to load . Thus, the elastic force of the spring 67 pressing the first spool 61 is smaller in a range where the movement amount of the first spool 61 is small than in a large range. This allows
In a region where the vehicle speed is small and the orifice 63 is closed by a slight movement of the first spool 61, the amount of movement of the first spool 61 is large even if the change in the steering input torque is small and the change in the load applied to the spring 67 is small. Therefore, the orifice 63 is closed, and the increase rate of the hydraulic pressure acting on the cylinder 20 increases. On the other hand, as the vehicle speed increases, the change in the steering input torque is large and the change in the load applied to the spring 67 is large, but the orifice is not closed because the amount of movement of the first spool 61 is small. The rate of increase does not increase. That is, the change of the steering force with respect to the speed change is larger in the low speed region than in the high speed region. When the spring 67 having such a non-linear characteristic receives a large initial load due to the deviation of the dimensional accuracy of the components of the control valve 60 , that is, the steering 67
Close the orifice of one spool according to the input torque
In the state before the action of hydraulic pressure to move
If the load applied to the spring 67 increases , the steering characteristics cannot be achieved. Therefore, it is preferable to set the initial load of the spring 67 to substantially zero. Such setting of the initial load can be performed by adjusting the screwing amount of the cap 68 into the female screw hole 7a.

The present invention is not limited to the above embodiment.

[0028]

For example, as shown in FIG. 8, between the inlet port 34a on the pump 33 side and the inlet port 34b on the control valve 30 side, a step 6 on the inner circumference of the first spool 61 is provided.
A second orifice 80 is formed by 1b and the convex portion 62a on the outer periphery of the second spool 62. When the second spool 62 moves upward in the drawing at a high speed, the opening of the second orifice 80 is reduced. Thereby, the pump 33
Oil discharged from the first spool 6 from the port 34a
It is squeezed when passing through the second orifice 80 via one through hole 64a, and then reaches the port 34b from the through hole 64b of the first spool. According to the present embodiment, the hydraulic pressure acting on the restricting means 51 at a high speed is larger than at the time of the above embodiment, and the straight running stability at a high speed can be further improved. Other parts are the same as those in the above embodiment, and the same parts are indicated by the same reference numerals.

[0030]

According to the hydraulic power steering apparatus of the present invention, a desired steering can be achieved by adjusting the elastic force and the initial load of the spring pressing one of the spools regardless of the dimensional accuracy of the components constituting the adjusting valve. Properties can be obtained.

[Brief description of the drawings]

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

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

FIG. 3 is a sectional view for explaining the operation of the control valve according to the embodiment of the present invention;

FIG. 4 is a sectional view for explaining the operation of the control valve according to the embodiment of the present invention;

FIG. 5 is a sectional view for explaining the operation of the control valve according to the embodiment of the present invention;

FIG. 6 is a plan view of a cap of the control valve according to the embodiment of the present invention;

FIG. 7 is a characteristic diagram of the spring according to the embodiment of the present invention.

FIG. 8 is a sectional view of a control valve according to another embodiment of the present invention.

FIG. 9 is a diagram showing a relationship between input torque and hydraulic pressure acting on a hydraulic cylinder.

FIG. 10 is a sectional view of a hydraulic power steering device according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hydraulic power steering device 2 Input shaft 3 Torsion bar 4 Output shaft 7 Housing 20 Hydraulic actuator 30 Control valve 51 Restriction means 60 Adjustment valve 61 First spool 62 Second spool 63 Orifice 67 Spring 68 Cap

Claims (1)

(57) [Scope of request for utility model registration] 1. An input shaft for 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 pump through a control valve. A hydraulic actuator that is actuated by the supplied hydraulic oil to apply a steering assist force; regulating means for regulating the torsion of the torsion bar by the action of hydraulic pressure; and a hydraulic pressure adjusting valve acting on the regulating means. The control valve has a pair of spools inserted into the housing , and one of the spools is axially movably inserted into the housing.
And the other spool is axially
Relative to the pump and the regulating means by the relative axial movement of both spools.
The orifice that opens and closes between the pumps is controlled from the pump
The pressure of the oil flowing into the valve is regulated through this orifice.
The one spool is moved in the direction of opening the orifice by elastic force.
The spring that moves axially with respect to the housing
The spring is provided inside the ring, and the spring is smaller in the area where the load is small than in the area where the load is large.
Non-linear characteristics with large deflection change with full load
Is intended to, one of the spool, to an increase in hydraulic pressure applied to the regulating means
Axial direction to the housing in the direction to close the orifice
The other spool can be moved relative to one spool to reduce vehicle speed.
When the orifice is moved in the axial direction to close the
Both shift in the axial direction to open the orifice due to the increase in vehicle speed.
A hydraulic power steering device in which a moving means is attached to a housing , wherein an elastic force of the spring is adjustable from outside the housing, and one of the spools of the spring is orificed.
To the state before the hydraulic pressure was applied to move the
Hydraulic power steering apparatus characterized by the definitive load weight is set to substantially zero.