JP2003137117A - Power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power steering device wherein manual steering is possible even when both a reversible pump and a bypass valve are locked by using a pair of poppet valves as the bypass valve and capable of preventing deterioration of steering feeling caused by using the pair of poppet valves. SOLUTION: The power steering device is provided with a first bypass passage 45 and a second bypass passage 46 respectively connected with midway parts of a first communication passage 34 and a second communication passage 35 between a ball valve element (a first check valve) 39a and a ball valve element (a second check valve) 40a and a hydraulic power cylinder 27 and communicated with a reservoir tank 38, and the normally opened first poppet valve 47 and second poppet valve 48 respectively interposed in the first bypass passage 45 and the second bypass passage 46 and respectively switching between communication and cutoff of the first bypass passage 45 and the second bypass passage 46 on the basis of hydraulic pressure signals from the first communication passage 34 and the second communication passage 35.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering system, and more particularly to a system for generating a steering assist force by a hydraulic power cylinder.

[0002]

2. Description of the Related Art A conventional power steering device of this type is known, for example, from Japanese Patent Application Laid-Open No. 57-201767.

In this conventional power steering apparatus, as shown in FIG. 6, a reversible oil pump 102 is driven by rotating an electric motor 101 in a normal or reverse direction, and the hydraulic pressure pressurized by the reversible oil pump 102 is supplied. The steering assist force is generated by selectively supplying the oil to the respective oil chambers 105a and 105b of the power cylinder 105 via the oil passages 103 and 104. Orifices 106 and 107 are provided in the middle of the oil passages 103 and 104, respectively.
A bypass passage 108 that connects the oil passages 103 and 104 is connected between the oil passage 107 and the oil chambers 105a and 105b, and the bypass valve 10 is connected to the bypass passage 108.
9 is installed. Then, the bypass valve 109
Has a valve body 110 in which a large diameter portion 110b is continuously provided on both sides of a small diameter portion 110a in a valve body 111, and springs 11 having the same spring constant are provided on both sides of the valve body 110.
2a and 112b are respectively compressed, and the valve chambers 113a and 113b formed on both sides of the valve body 110 are
Through the pilot passages 114a and 114b, the oil passages 103 and 104 between the reversible oil pump 102 and the orifices 106 and 107 are communicated with each other.

That is, during steering assist, the reversible oil pump 102 rotates and is selectively supplied to either of the oil chambers 105a and 105b of the power cylinder 105. At that time, due to the existence of the orifices 106 and 107, A pressure difference occurs near the discharge port of the reversible oil pump 102,
This pressure difference acts on both valve chambers 113a and 113b via the pilot passages 114a and 114b, so that the valve element 110 of the bypass valve 109 blocks the bypass passage 108.

[0005]

However, in the conventional power steering apparatus, as described above,
One bypass valve 10 is used to open and close the bypass passage 108.
This bypass valve 109
Is constituted by a spool valve, and therefore, when the bypass valve 109 is locked while the bypass passage 108 is in a closed circuit state due to contamination or the like, it is impossible to communicate hydraulic pressure between the oil chambers 105a and 105b of the power cylinder 105. And in this state, the reversible oil pump 102
If is locked, there is a problem in that the steering force of the driver will be forced more than necessary.

Therefore, in order to solve the above problems, 1
A method of using a pair of poppet valves 201 and 202 instead of one bypass valve 109 can be considered. When this pair of poppet valves 201 and 202 is applied to the circuit of FIG. 6, the circuit configuration as shown in FIG.
08 and the poppet valve 20 for shutting off the bypass passage 108
Even if contamination or the like is sandwiched between the valve bodies 1 and 202 and the operation is locked, the bypass passage 108 becomes an open circuit, and thus the reversible oil pump 102 is in this state.
Even when the vehicle is locked, the hydraulic pressures in the two oil chambers 105a and 105b of the power cylinder 105 are maintained, so that steering assist force cannot be obtained, but in the manual steering, the driver's steering force may be forced more than necessary. Absent.

However, when the poppet valve 201 is shut off so as to supply the hydraulic pressure to one oil chamber 105a side, the exhaust pressure discharged from the other oil chamber 105b side passes through the oil passage on the other poppet valve 202 side. There is a problem in that the shut-off of the poppet valve 201 on one side may be delayed by acting on the valve body of the poppet valve 201 on the other hand in the opening direction, which may worsen the steering feeling.

The present invention has been made in view of the above-mentioned conventional problems, and by using a pair of poppet valves as the bypass valve, manual steering can be performed even when both the reversible pump and the bypass valve are locked. An object of the present invention is to provide a power steering device that is capable of preventing deterioration of steering feeling caused by using a pair of poppet valves.

[0009]

In order to achieve the above-mentioned object, a power steering apparatus according to claim 1 of the present invention comprises a steering shaft linked to a steering mechanism and a hydraulic pressure for assisting the steering force of the steering mechanism. The power cylinder, a reversible pump having a pair of discharge ports for supplying hydraulic pressure to the respective hydraulic chambers of the hydraulic power cylinder via the first communication passage and the second communication passage, and the reversible pump An electric motor for reverse rotation drive, and a first check valve that is interposed in the middle of the first communication passage and the second communication passage and allows only the flow from the reversible pump in the hydraulic power cylinder direction, and A second check valve, a steering direction detecting means for detecting a rotating direction of the steering shaft, a steering force detecting means for detecting a steering force acting on the steering shaft, and a steering force detected by the steering force detecting means. Signal and Between the electric motor control means for outputting a drive signal to the electric motor based on the rotation direction signal of the steering shaft detected by the steering direction detection means, the hydraulic power cylinder, the first check valve and the second check valve. The first bypass passage and the second bypass passage, which are respectively connected to the first communication passage and the second communication passage of
The bypass passage and the first bypass passage and the second bypass passage, respectively, are respectively interposed based on the hydraulic signals from the first communication passage and the second communication passage.
The normally open first poppet valve and the second poppet valve that switch between communication and interruption of the bypass passage and the second bypass passage are provided.

A power steering apparatus according to a second aspect is the power steering apparatus according to the first aspect,
The first poppet valve and the second poppet valve are provided so as to face each other in the same axis line in the shutoff direction, and at least one of the first poppet valve and the second poppet valve has an axially facing surface. When either one of the poppet valves is actuated in the direction to block the bypass passage by directly or indirectly abutting the other, the other poppet valve is prevented from blocking the bypass passage. The means for restricting the operating range of is provided.

A power steering apparatus according to a third aspect is the power steering apparatus according to the second aspect,
A communication hole is provided which communicates between the first bypass passage and the second bypass passage between the first poppet valve and the second poppet valve and the reservoir tank on the opposite axis of the first poppet valve and the second poppet valve. The regulating means are provided on both the first poppet valve and the second poppet valve, respectively, and both regulating means are provided so as to be constantly inserted into the communication hole, so that the regulating means are directly connected to each other. The means is provided so as to be in contact with.

[0012]

In the power steering system according to claim 1 of the present invention, as described above, the first communication passage and the second communication passage between the hydraulic power cylinder and the first check valve and the second check valve are in the middle. A first bypass passage and a second bypass passage which are respectively connected to the reservoir tank and communicate with the reservoir tank; and a first bypass passage and a second bypass passage which are respectively interposed in the first bypass passage and the second bypass passage. Since it is configured to include a normally open first poppet valve and a second poppet valve that switch communication / cutoff of the first bypass passage and the second bypass passage based on the hydraulic signal, respectively.
Manual steering is possible even when both the reversible pump and the bypass valve are locked.
Since the first bypass passage and the second bypass passage having the poppet valve and the second poppet valve, respectively, communicate with each other only via the reservoir, one poppet valve is shut off to supply the hydraulic pressure to one hydraulic chamber side. In doing so, the exhaust pressure discharged from the other hydraulic chamber side does not act on the other poppet valve side, and therefore occurs by using the pair of poppet valves (first poppet valve and second poppet valve). It becomes possible to prevent the deterioration of the steering feeling.

Since the power steering apparatus according to the second aspect is configured as described above, when one of the poppet valves is operated in the direction of blocking the bypass passage, the other of the poppet valves is operated by the restricting means. The operation range of the poppet valves is regulated so that the bypass passage is not blocked. Therefore, in the steering direction in which the steering assist force is generated by closing the normal poppet valve side, the steering assist force cannot be obtained, which is perceived as a change in the steering feeling, which causes the driver's abnormality in the device. You will be able to recognize immediately.

In the power steering apparatus according to the third aspect, as described above, the first bypass passage between the first poppet valve and the second poppet valve and the reservoir tank and the second bypass passage are provided with the first bypass passage. A communication hole communicating with the opposite axis of the poppet valve and the second poppet valve is provided, and the restricting means is provided in both the first poppet valve and the second poppet valve, and both restricting means are in the communication hole. Since it is provided in such a state that it is always inserted through, the configuration is such that both regulating means directly contact each other, compared to the case where both regulating means are provided indirectly contacting each other. It becomes possible to simplify.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment of the Invention) First, the configuration of the first embodiment of the present invention will be described with reference to FIG.

FIG. 1 is an overall schematic configuration diagram showing a power steering device according to a first embodiment of the invention. As shown in FIG. 1, a steering shaft 22 to which a steering wheel 21 as a steering input means is connected, The rack and pinion 24 provided on the output shaft 23 at the lower end of the steering shaft 22, and the rotation direction of the steering shaft 22 provided at the lower end of the output shaft 23 and the steering force acting on the steering shaft 22 are detected. A steering force sensor 26 (steering direction detecting means, steering force detecting means), a hydraulic power cylinder 27 connected to the rack, and a hydraulic circuit 28 for supplying and discharging hydraulic pressure to and from the hydraulic power cylinder 27.
Is equipped with.

In the hydraulic power cylinder 27, a piston rod 30 connected to the rack penetrates through a cylindrical cylinder portion 29 extending in the vehicle width direction, and the cylindrical rod portion 29 is connected to the piston rod 30. A piston 31 that slides inside is fixed. In addition, the cylindrical cylinder portion 2
A left and right first hydraulic chamber 32 and a second hydraulic chamber 33 are separated from each other by a piston 31 inside 9. 25a, 25
Reference characters b are left and right front wheels connected to both ends of the piston rod 30 via links.

The hydraulic circuit 28 has a pair of first communication passage 34 and second communication passage 35, one end of which is connected to the hydraulic chambers 32 and 33, and the other end of the two communication passages 34 and 35. One reversible pump 37 which is provided with a pair of discharge ports 37a and 37b connected to and can be rotated forward and backward by a pump motor (electric motor) 36, and is arranged upstream of the reversible pump 37 and A reservoir tank 38 that stores hydraulic oil, a first pressure control valve 39 and a second pressure control valve 40 that are interposed in the middle of the first communication passage 34 and the second communication passage 35, and the first pressure control valve. 39 and communication passages 41 and 42 bypassing the second pressure control valve 40, respectively, and allow only the working fluid to flow from the first hydraulic chamber 32 and the second hydraulic chamber 33 toward the reversible pump 37. Check valves 43 and 44 Said first pressure control valve 39 and a second
Pressure control valve 40, first hydraulic chamber 32, and second hydraulic chamber 33
A first bypass passage 45 and a second bypass passage 46 which communicate between the reservoir tank 38 and the first communication passage 34 and the second communication passage 35, respectively, and the first bypass passage 45.
And the second bypass passage 46, respectively. The first bypass passage 45 and the second bypass passage 45 are respectively provided based on the hydraulic signals from the first communication passage 34 and the second communication passage 35.
The normally open first for switching between communication and interruption of the bypass passage 46.
A poppet valve 47 and a second poppet valve 48.

More specifically, the both pressure control valves 3 will be described.
The reference numerals 9 and 40 have ball valve bodies 39a and 40a which form a first check valve and a second check valve which allow only the flow of hydraulic oil from the reversible pump 37 to the hydraulic power cylinder 27 direction. Return springs 39b, 40 for biasing the ball valve elements 39a, 40a in the closing direction with a predetermined load
b is provided, and a differential pressure is generated between the hydraulic power cylinder 27 side and the reversible pump 37 side by this biasing force.

The first poppet valve 47 and the second poppet valve 48 are provided so as to face each other on the same axis in the shut-off direction, and are provided in the middle of the first bypass passage 45 and the second bypass passage 46. A pair of cylindrical valve holes 47b, 48b arranged substantially in series is formed, and inside each of the valve holes 47b, 48b is formed an outer pressure receiving chamber 47c, 48c and an inner communication chamber 47d, 48d. The substantially cylindrical valve bodies 47a and 48a defining the above are slidably provided. Then, the inner communication chambers 47d, 4
8d is interposed in the middle of the first bypass passage 45 and the second bypass passage 46, and the communication chamber 4 inside this is provided.
In the middle of 7d and 48d, the inner communication chambers 47d and 48d are provided.
Valve openings 47e and 48e for communicating / cutting off the valve openings 47e and 48e of the valve bodies 47a and 48a are opened and closed by opening and closing the valve openings 47e and 48e. The bypass passage 46 is connected / disconnected.

A communication hole 49 is formed between the inner communication chambers 47d, 48d, and the valve portion 47f,
Stopper members 47g and 48g are formed so as to project at the tip end axial portion of 48f with the tip end inserted into the communication hole 49. The stopper members 47g, 48
As for g, one of the valve portions 47f and 48f has a valve opening 47
In a state in which one of the stopper members 47g and 48e is in contact with one of the first bypass passage 45 and the second bypass passage 46, the front end surfaces of the stopper members 47g and 48g contact each other in the communication hole 49. By making contact with each other, the other of the valve openings 47e and 48e serves to regulate at least the closed state. In addition,
Seal rings 47h and 48h are attached to the outer peripheral portions of the valve bodies 47a and 48a. In addition, both valve bodies 4
7a and 48a are formed in the same shape including the stopper members 47g and 48g.

Inside the communication chambers 47d and 48d on the inner side, the first bypasses are pushed inside the valve openings 47e and 48e by pressing the valve bodies 47a and 48a in the directions to open the valve openings 47e and 48e, respectively. The spring 4 for urging the passage 45 and the second bypass passage 46 in a direction to always open them.
7j and 48j are interposed.

The outer pressure receiving chambers 47c and 48c are also provided.
Are the first introduction passage 50 and the second introduction passage 51, respectively.
Through the pressure control valves 39 and 40 and the reversible pump 37, the first communication passage 34 and the second communication passage 35 are communicated with each other. By the way, the pressure chambers 47c, 48c on the outer side and the communication chamber 47d on the inner side, which face each other with the valve bodies 47a, 48a interposed therebetween,
The 48d side is connected to the first communication passage 34 and the second communication passage 35 between the pressure control valves 39 and 40 and the hydraulic power cylinder 27 via the first bypass passage 45 and the second bypass passage 46. And both pressure control valves 3
Due to the pressure difference generated before and after 9, 40, the valve elements 47a, 4
8a operates so as to close the valve openings 47e and 48e. Further, the outer pressure receiving chambers 47c, 4
8c is connected to a substantially downstream side of the reversible pump 37 by a first introduction passage 50 and a second introduction passage 51, and the hydraulic pressure of the immediate downstream is directly supplied.

The reservoir tank 38 stores the working oil stored therein through the supply path 52 and the reversible pump 37.
In addition to supplying and replenishing the hydraulic oil, the operating oil leaked from each component of the reversible pump 37 is collected. The motor pump 36 is a controller (electric motor control means) 5 equipped with a microcomputer.
The forward and reverse rotation control is performed by the control current output from the controller 3. The controller 53 outputs the control current by calculation based on the information signal such as the steering input torque from the steering force sensor 26. .

Next, the operation and effect of the first embodiment of the present invention will be described. (B) Normal operation of both poppet valves First, when the driver rotates the steering wheel 21 to the left as shown by the arrow in the figure while driving the vehicle in a normal manner, as shown in FIG. For example, the reversible pump 37 is driven in the normal direction as the pump motor 36 is controlled in the normal direction by the control signal from the controller 53. A part of the hydraulic oil discharged into the first communication passage 34 due to the pump action is from the first introduction passage 50 to the pressure receiving chamber 47c.
Is higher than the hydraulic pressure of the hydraulic oil that has passed through the first pressure control valve 39, the differential pressure causes the valve body 47a on the first poppet valve 47 side to resist the biasing force of the spring 47j. As shown, the valve body 47a is pressed rightward to close the valve opening 47e. On the other hand, the valve body 48a on the second poppet valve 48 side is maintained in a state in which the valve port 48e is opened by the urging force of the spring 48j.

As a result, the hydraulic oil discharged from the reversible pump 37 causes the ball valve element 3 of the first pressure control valve 39 to operate.
9a is supplied to the first hydraulic chamber 32 while pushing open against the urging force of the return spring 39b, and at the same time, the reversible pump 37 suctions the second hydraulic chamber 33 into the second communication passage 35. As shown by the arrow, the operated hydraulic fluid once flows into the second bypass passage 46 and then enters the communication passage 42, where the check valve 44 is opened and the second bypass passage 46 is opened again.
While being sucked into the reversible pump 37 from the communication passage 35,
Communication chamber 48d provided in the middle of the second bypass passage 46
And is returned to the reservoir tank 38 via.

Therefore, the hydraulic pressure is relatively supplied to or discharged from the first hydraulic chamber 32 and the second hydraulic chamber 33 to give an assisting force to the counterclockwise steering force of the steering wheel 21 by the driver. The load of the left-handed steering can be reduced, and the operability of the steering wheel 21 can be improved. Further, in the state in which the left rotation steering state is maintained, the power supply to the pump motor 36 is cut off, and the hydraulic circuit 28 is closed, so that the state in which the hydraulic pressure is applied to the first hydraulic chamber 32 is Maintained.

As described above, the first bypass passage 45
And the second bypass passage 46, the two communication chambers 47d, 48
The portion d is in a state of being communicated with each other by the communication hole 49. In this communication hole 49, both stopper members 47g, 4g,
The passage is narrowed by inserting 8 g, and the communication chamber 47d (first bypass passage 45) and the communication chamber 48d (second bypass passage 46) are at atmospheric pressure. It is in a state of being communicated with each other via the tank 38. Therefore, when the first poppet valve 47 is shut off in order to supply the hydraulic pressure to the one first hydraulic chamber 32 side, the exhaust pressure discharged from the other second hydraulic chamber 33 side acts on the first poppet valve 47 side. There is no risk of disturbing the shut-off operation of the first poppet valve 47, thereby preventing deterioration of steering feeling caused by using the pair of poppet valves (the first poppet valve 47 and the second poppet valve 48). The effect of being able to do is obtained.

On the other hand, when the steering wheel 21 is returned to the original state from the left rotation steering state and the driver further steers the steering wheel 21 rightward as shown by the arrow in FIG. 3, the controller 53 causes the pump motor to rotate. By reversing the reversible pump 37 via 36, this causes the hydraulic oil to be discharged to the second communication passage 35, contrary to the above, and similarly to the above, the first hydraulic chamber 32 and the second hydraulic chamber 32. The hydraulic pressure is relatively supplied to or discharged from the steering wheel 33 to give an assisting force to the clockwise rotation steering force of the steering wheel 21 by the driver. This reduces the load of the clockwise rotation steering and operates the steering wheel 21. It is possible to improve the sex. Even in this right rotation steering state, the same operation / operation as in the left rotation steering state is performed.
The effect is obtained.

(B) When the reversible pump is locked The reversible pump 37 is locked and becomes inoperative due to, for example, an electrical failure of the pump motor 36 or a mechanical failure of the reversible pump 37. In this case, since the hydraulic pressure from the reversible pump 37 does not act on the pressure receiving chambers 47c and 48c from the first introduction passage 50 and the second introduction passage 51, the first poppet valve 47 and the second poppet valve 48 are not affected. As shown in FIG. 1, the valve bodies 47a and 48a are actuated by the urging forces of both springs 47j and 48j.
Are kept open, whereby the first bypass passage 45 and the second bypass passage 46 are in communication with each other via the reservoir tank 38. Therefore, although the reversible pump 37 is locked, the steering assist force disappears, but the driver can ensure manual steering of the steering wheel 21.

(C) When the poppet valve is locked Either one of the valve bodies 47a, 48a of the first poppet valve 47 and the second poppet valve 48 has a valve opening 47e, 48e.
When either one of them is locked in the closed state, for example, as shown in FIG. 4, the valve body 4 on the first poppet valve 47 side is
When 7a is locked with the valve opening 47e closed,
When steering the steering wheel 21 to the left,
Since the valve opening 47e is in the closed state from the beginning, the same operation as that described in (a) the normal operation of both poppet valves is performed, and the left rotation steering force of the steering wheel 21 is assisted. Power is given.

However, as indicated by the arrow in FIG. 4, during the clockwise rotation steering, the valve element 47 on the first poppet valve 47 side.
Since a is locked with the valve opening 47e closed, the stopper members 47g and 48 of both valve bodies 47a and 48a are locked.
When the leading end surfaces of g contact each other, the other valve port 48
e cannot be blocked. Therefore, the hydraulic oil discharged from the reversible pump 37 to the second communication passage 35 side is
It is discharged to the reservoir tank 38 via the pressure control valve 40 and the valve port 48e in the second bypass passage 46.
Therefore, since the steering assist force is not obtained, it is known as a change in the steering feeling, and thus the driver can immediately recognize the occurrence of the abnormality in the device.

Further, since both valve bodies 47a and 48a are formed in the same shape including both stopper members 47g and 48g, the cost can be reduced by sharing the parts. Further, since the two valve bodies 47a and 48a are not always connected by the two stopper members 47g and 48g, the first poppet valve 47 and the second poppet valve 48 are mutually connected in the normal state of the device. It operates independently, so that the sliding friction and the urging forces of the springs 47j and 48j only act individually. Therefore, the respective operations are smooth, and the operation responsiveness of the first poppet valve 47 and the second poppet valve 48 can be improved.

Further, the first communication passage 34 and the second communication passage 3
In the middle of 5, the first pressure control valve 39 and the second pressure control valve 4
0, the first poppet valve 47 and the second poppet valve 4
8 is a first bypass passage 45 and a second bypass passage 46, respectively, based on the hydraulic signals of the first communication passage 34 and the second communication passage 35 upstream of the first pressure control valve 39 and the second pressure control valve 40. By being configured to open and close
Since the discharge fluid pressure from the reversible pump 37 can be directly received and actuated, the actuation responsiveness of the first poppet valve 47 and the second poppet valve 48 can be improved.

Next, another embodiment of the present invention will be described. In the description of the other embodiments of the present invention, the same components as those of the first embodiment of the present invention will not be illustrated and described, or will be denoted by the same reference numerals and the description thereof will be omitted, Only the points will be described.

(Second Embodiment of the Invention) A power steering apparatus according to a second embodiment of the present invention has both stopper members (regulating members) 47 as shown in the overall schematic configuration view of FIG.
g, 48 g and the communication hole 49 are omitted, which is a difference from the first embodiment of the invention. Therefore, in the second embodiment of the present invention, the same effect as that of the first embodiment of the invention can be obtained except that the effect of (c) in the first embodiment of the invention is not obtained. It is possible to simplify the device.

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configurations are not limited to the embodiments of the present invention, and there are design changes and the like within the scope not departing from the gist of the present invention. Also included in the present invention. For example,
In the embodiment of the invention, the first bypass passage 45 and the second bypass passage 46 are connected to the first communication passage 34 and the second communication passage 35, respectively, but are directly connected to both the hydraulic chambers 32 and 33 of the hydraulic power cylinder 27. You may make it connect.

In the first embodiment of the invention, the first poppet valve 47 and the second poppet valve 48 are used as the regulating members.
Although the stopper members 47g and 48g are provided on both of them, they may be provided on only one of them. Further, in the first embodiment of the invention, the stopper members 47g and 48g as the regulating members are directly contacted in the communication hole 49, but they are indirectly contacted without providing the communication hole 49. It is also possible to have a structure that allows it. In the embodiment of the invention, the pressure control valve is used as the means for generating the differential pressure, but an orifice may be used.

Also, for example, one of the first poppet valves 47
Of the other poppet valve 48 when the valve body 47a on the side is locked with the valve opening 47e closed.
The opening degree of 8e is arbitrary, and in addition to the case where the steering assist force is not obtained at all in the fully opened state, the steering assist force may be weakened by setting it to a slightly narrowed state. it can.

[0040]

As described above, the present invention claims 1.
In the power steering apparatus described above, as described above, the reservoir tank is connected in the middle of the first communication passage and the second communication passage between the hydraulic power cylinder and the first check valve and the second check valve, respectively. A first bypass passage and a second bypass passage, which are in communication with the first bypass passage and the second bypass passage, respectively, based on hydraulic signals from the first communication passage and the second communication passage, respectively. Communication between the first bypass passage and the second bypass passage /
Since the first poppet valve and the second poppet valve that are normally open for switching the cutoff are provided, the manual steering is possible even when the reversible pump and the bypass valve are both locked, and the first poppet valve is also provided. Since the first bypass passage and the second bypass passage having the poppet valve and the second poppet valve, respectively, communicate with each other only via the reservoir, one poppet valve is shut off to supply the hydraulic pressure to one hydraulic chamber side. In doing so, the exhaust pressure discharged from the other hydraulic chamber side does not act on the other poppet valve side, and therefore occurs by using the pair of poppet valves (first poppet valve and second poppet valve). The effect that it becomes possible to prevent the deterioration of the steering feeling is obtained.

A power steering apparatus according to a second aspect is the power steering apparatus according to the first aspect,
The first poppet valve and the second poppet valve are provided so as to face each other on the same axis in the shutoff direction, and at least one of the first poppet valve and the second poppet valve has an axially opposite surface on the other side. When either one of the poppet valves is actuated in the direction to block the bypass passage by directly or indirectly contacting with the other, the other poppet valve is operated so that it does not block the bypass passage. Since the means for restricting the range is provided, the steering assist force cannot be obtained in the steering direction in which the steering assist force is generated by closing the normal poppet valve side, so that the steering feeling It is perceived as a change, which allows the driver to immediately recognize the occurrence of equipment malfunction.

A power steering apparatus according to a third aspect is the power steering apparatus according to the second aspect,
A communication hole is provided which communicates between the first bypass passage and the second bypass passage between the first poppet valve and the second poppet valve and the reservoir tank on the opposite axis of the first poppet valve and the second poppet valve. The restricting means is provided on both the first poppet valve and the second poppet valve, and both restricting means are provided so as to be constantly inserted into the communication hole, so that the restricting means directly contact each other. By adopting the means provided in this state, the configuration can be simplified as compared with the case where both regulating means are provided in the state of indirectly contacting each other.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an entire power steering device according to a first embodiment of the invention.

FIG. 2 is an operation explanatory diagram showing a state of the power steering device according to the first embodiment of the present invention during left steering.

FIG. 3 is an operation explanatory diagram showing a state of the power steering device according to the first embodiment of the invention when steering to the right.

FIG. 4 is an operation explanatory view showing a state when the power steering device according to the first embodiment of the present invention fails.

FIG. 5 is an overall schematic configuration diagram showing a power steering device according to a second embodiment of the invention.

FIG. 6 is an overall schematic configuration diagram showing a conventional power steering device.

FIG. 7 is a cross-sectional view of essential parts showing an example in which a pair of poppet valves is applied to a conventional power steering device.

[Explanation of symbols]

21 Steering Wheel 22 Steering Shaft 23 Output Shaft 24 Rack and Pinion 25a Left Front Wheel 25b Right Front Wheel 26 Torque Sensor (Steering Force Detection Means / Steering Direction Detection Means) 27 Hydraulic Power Cylinder 28 Hydraulic Circuit 29 Cylindrical Cylinder 30 Piston Rod 31 Piston 32 1st hydraulic chamber 33 2nd hydraulic chamber 34 1st communicating path 35 2nd communicating path 36 Pump motor 37 Reversible pump 37a Discharge port 37b Discharge port 38 Reservoir tank 39 1st pressure control valve 39a Ball valve body (1st reverse) 39b Return spring 40 Second pressure control valve 40a Ball valve element (second check valve) 40b Return spring 41 Communication passage 42 Communication passage 43 Check valve 44 Check valve 45 First bypass passage 46 Second bypass passage 47 1st poppet valve 47a Valve body 47b Valve hole 47c Pressure receiving chamber 47d Communication chamber 7e Valve port 47f Valve part 47g Stopper member (regulating means) 47h Seal ring 47j Spring 48 Second poppet valve 48a Valve body 48b Valve hole 48c Pressure receiving chamber 48d Communication chamber 48e Valve port 48f Valve part 48g Stopper member (regulating means) 48h Seal Ring 48j Spring 49 Communication hole 50 First introduction passage 51 Second introduction passage 52 Supply passage 53 Controller (electric motor control means)

Claims (3)

[Claims] 1. A steering shaft linked to a steering mechanism, a hydraulic power cylinder for assisting the steering force of the steering mechanism, and a first communication passage and a second communication passage for both hydraulic chambers of the hydraulic power cylinder. A reversible pump having a pair of discharge ports that respectively supply hydraulic pressures, an electric motor that drives the reversible pump in forward and reverse rotations, and is installed in the middle of the first communication passage and the second communication passage, respectively. A first check valve and a second check valve that allow only flow from the reversible pump in the hydraulic power cylinder direction; steering direction detection means that detects the rotation direction of the steering shaft; and the steering shaft. Steering force detecting means for detecting the steering force acting on the electric motor, and a drive signal for the electric motor based on the steering force signal detected by the steering force detecting means and the rotation direction signal of the steering shaft detected by the steering direction detecting means. Is connected to the hydraulic power cylinder and the first check valve and the second check valve between the hydraulic power cylinder and the first check valve and the second check valve, respectively, to communicate with the reservoir tank. The first bypass passage and the second bypass passage, and the first bypass passage and the second bypass passage are respectively interposed based on the hydraulic signals from the first communication passage and the second communication passage. A power steering device comprising: a first poppet valve and a second poppet valve, which are normally open and which switch between communication and interruption of the first bypass passage and the second bypass passage. 2. The first poppet valve and the second poppet valve are provided so as to face each other in the same axis line in the shutoff direction, and at least one of the first poppet valve and the second poppet valve includes: When one of the poppet valves operates in the direction to block the bypass passage by directly or indirectly contacting the axially opposite surfaces, the other poppet valve blocks the bypass passage. The power steering apparatus according to claim 1, further comprising a restriction unit that restricts the operating ranges of the power steering devices so that the power steering devices do not become inoperative. 3. The first bypass passage and the second bypass passage between the first poppet valve and the second poppet valve and the reservoir tank communicate with each other on the opposing axis of the first poppet valve and the second poppet valve. Is provided in both the first poppet valve and the second poppet valve, and both regulating means are provided in such a state that they are always inserted into the communicating hole. The power steering apparatus according to claim 2, wherein the means are provided in a state of directly abutting each other.