JP2004314765A - Steering gear for vehicles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem wherein an operation oil is fed to a hydraulic actuator on or after twisting is generated on a steering shaft continued to a steering member in a hydraulic power steering device, the operation oil is fed to the hydraulic actuator on or after deviation of a steering angle and a steering angle is generated in a hydraulic steer-by-wire type steering device for a vehicle and responsiveness of feeding of the operation oil against the operation of the steering member is bad in either case. <P>SOLUTION: In the steering device 1 for the vehicle comprising the hydraulic type power steering device, when the operation of the steering member 2 is started, the starting of the operation is quickly detected based on a steering speed Va and a flow rate control valve 16 is controlled by a motor 20 to feed/discharge the operation oil to the hydraulic actuator 7 at the feed/discharge amount corresponding to the steering speed Va. Steering assist force can be generated without delaying from the operation of the steering member 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicle steering device that generates a steering force or a steering assist force for changing the direction of a wheel using a hydraulic actuator.
[0002]
[Prior art]
The vehicle steering system includes a link type in which a steering member such as a steering wheel is mechanically connected to a steering mechanism via a transmission member such as a steering shaft, and a steering system in which the steering member is mechanically connected to the steering mechanism. It is roughly divided into the steer-by-wire type that is not performed.
In the former type of link type, in a power steering device using hydraulic pressure, the control valve is driven by the hydraulic oil on the left and right of the hydraulic actuator (power cylinder) due to the twist between the input shaft and the output shaft which are coaxially connected via a torsion bar. The flow of hydraulic oil into and out of the chamber is controlled, and steering is assisted by the hydraulic pressure generated by a hydraulic actuator.
[0003]
As the latter steer-by-wire system, a hydraulic actuator is provided as a steering actuator in the middle of the steering mechanism, and when an abnormality occurs in the drive of the service valve that controls the supply and discharge of hydraulic oil to and from this hydraulic actuator, the emergency valve There is a vehicle steering system provided with oil supply means for supplying hydraulic oil from a hydraulic actuator to a hydraulic actuator (for example, Patent Document 1).
[0004]
[Patent Document 1]
JP-A-2002-137748
[Problems to be solved by the invention]
In the former link-type hydraulic power steering device, the opening of a commonly used rotary control valve depends on the amount of twist of the steering shaft. That is, after the steering shaft is twisted, the hydraulic oil is supplied to the hydraulic actuator via the control valve. For this reason, when the steering member such as the steering wheel is operated quickly, there is a problem that the rise of the assist force is delayed with respect to this operation, and the operation of the steering member becomes heavy. Further, for example, there is a possibility that active steering such as when performing counter running on a snowy road or the like may not be adjusted.
[0006]
Further, in the latter, a steer-by-wire hydraulic steering apparatus for a vehicle disclosed in Patent Document 1, when a valve (service valve) is opened in proportion to the steering angle of the steering member, the rotation of the steering member at a required steering angle is performed. Even after stopping, hydraulic oil may flow into the hydraulic actuator, and steering may be continued. This is because a time lag occurs between the operation of the steering member and the flow of the hydraulic oil into the hydraulic actuator.
The present invention has been made in view of the above problems, and has as its object to provide a vehicular steering apparatus in which there is no delay in supply and discharge of hydraulic oil to and from a hydraulic actuator with respect to operation of a steering member.
[0007]
Means for Solving the Problems and Effects of the Invention
In order to achieve the above object, a first aspect of the present invention is a steering apparatus for a vehicle that generates a steering force or a steering assist force by a hydraulic actuator in response to an operation of a steering member, wherein the valve controls the flow of hydraulic oil into and out of the hydraulic actuator. A driving unit for operating the valve, a steering speed detecting unit for detecting a steering speed of the steering member, and a driving speed via the driving unit according to a steering speed detected by the steering speed detecting unit. Control means for controlling the operation of the valve.
[0008]
According to the present invention, for example, when applied to a hydraulic power steering apparatus, it is possible to detect that the steering by the steering member has been performed earlier than when twisting occurs in the steering shaft, and to obtain an assisting force corresponding thereto. Therefore, even if the steering member is quickly operated, the operation of the steering member does not become heavy. In addition, even in the case of a steer-by-wire system using a hydraulic actuator, it is possible to realize steering without delay with respect to operation of the steering member.
[0009]
In a second aspect based on the first aspect, the valve comprises a flow control valve, and the control means controls the flow control valve so that the flow rate of the flow control valve increases as the steering speed detected by the steering speed detection means increases. Is controlled. When a wheel is steered by a hydraulic actuator, the steering amount is proportional to the volume of hydraulic oil flowing into the hydraulic actuator. According to the present invention, when the steering speed is high, the flow rate of the hydraulic oil into the hydraulic actuator can be increased by the flow rate control valve, which is a speed control valve. Force can be generated without delay.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1 is a schematic diagram showing the overall configuration of a vehicle steering system according to one embodiment of the present invention.
In the present embodiment, a description will be given based on an example in which the vehicle steering device is a hydraulic power steering device.However, the present invention is directed to a steer-by-wire type vehicle steering device using a hydraulic actuator for steering described later. Is also applicable.
[0011]
Referring to FIG. 1, a vehicle steering system 1 includes an input shaft 3 that is integrally rotatably connected to a steering member 2 formed of, for example, a steering wheel, and a rack and pinion mechanism provided coaxially with the input shaft 3. And the like, an output shaft 5 connected to a steering mechanism 4, a torsion bar 6 connecting the input shaft 3 and the output shaft 5 so as to be relatively rotatable, and a hydraulic actuator 7 including a power cylinder for generating a steering assist force. And a well-known control valve 10 interposed between the hydraulic actuator 7 and the hydraulic pump 8 and the oil tank 9 to control the supply and discharge of hydraulic oil to and from the hydraulic actuator 7 in accordance with the torsion of the torsion bar 6.
[0012]
The steering mechanism 4 includes a pinion 4a that rotates integrally with the output shaft 5, and a rack shaft 4b that meshes with the pinion 4a and extends in the left-right direction of the vehicle. By moving the rack shaft 4b in the axial direction, the steering wheel 11 is steered.
The control hull 10 is fitted to the output shaft 5 so as to be rotatable integrally with the output shaft 5, and a valve rotor 10 b fitted to the inside of the valve body 10 a so as to be rotatable relative to the input shaft 3. including. Between the valve body 10a and the valve rotor 10b, there is provided a pair of throttles (not shown) whose throttle areas change in different directions according to the relative angular displacement of the two 10a, 10b.
[0013]
The hydraulic actuator 7 forms a cylinder chamber 12 by liquid-tightly sealing a part of a cylindrical rack housing (not shown) surrounding the outside of the rack shaft 4b. A piston 13 fixed at an intermediate portion of the rack shaft 4b is slidably fitted in the cylinder chamber 12, and is applied to the rack shaft 4b by a differential pressure between the oil chambers 7a and 7b on both sides of the piston 13. The hydraulic pressure directly assists the steering operation performed along the axial direction of the rack shaft 4b.
[0014]
Specifically, when the steering member 2 is operated, the input shaft 3 rotates around the axis, and this rotation is transmitted to the rack shaft 4b via the torsion bar 6, the output shaft 5, and the pinion 4a. The rack shaft 4b slides in the axial direction to perform steering. At this time, a torsion corresponding to the steering torque applied to the steering member 2 is generated in the torsion bar 6 connecting the input shaft 3 and the output shaft 5. In response to this torsion, the valve body 10a of the control valve 10 and the valve rotor 10b undergo relative angular displacement, and pressure oil from the hydraulic pump 8 is supplied to a required oil chamber 7a or 7b of the hydraulic actuator 7. I have.
[0015]
The features of the present embodiment are as follows. That is, a pair of paths 15 that connect the hydraulic pump 8 and the oil tank 9 to the hydraulic actuator 7 via the control valve 10 are provided along with a pair of paths 15 as bypass paths that bypass the control valve 10. A flow control valve 16 for controlling the supply and discharge of hydraulic oil to and from the hydraulic actuator 7 is provided.
In the path 15, an electromagnetic direction control valve 17 is provided between the flow control valve 16 and the hydraulic pump 8 and the oil tank 9. The direction control valve 17 switches between the pair of paths 15 so as to selectively connect the hydraulic pump 8 to the oil chamber 7a or 7b of the hydraulic actuator 7 according to the steering direction.
[0016]
Further, a steering angle sensor 18 for detecting a steering angle of the steering member 2 is provided. The steering angle sensor 18 is connected to a control unit 19, and a signal detected from the steering angle sensor 18 is provided to the control unit 19 including a CPU, a ROM, a RAM, and the like.
The control unit 19 differentiates the steering angle A detected by the steering angle sensor 18 to detect a steering speed (steering angular speed) Va, and drives the flow control valve 16 in accordance with the detected steering speed Va. Is controlled via a drive circuit 21. As the motor 20, for example, a step motor can be used.
[0017]
Further, the control unit 19 detects the steering direction of the steering member 2 based on the steering angle A detected by the steering angle sensor 18, and controls the direction control valve 17 via the drive circuit 22 according to the detected steering direction. Control.
FIG. 2 shows a flow of the steering control by the control unit 19. The control unit 19 reads the steering angle A detected by the steering angle sensor 18 (step S1), and obtains a steering speed (steering angular speed) Va by differentiating the read steering angle A (step S2).
[0018]
When the steering speed Va is not zero (actually, when it deviates from an error region near zero) (NO in step S3), the magnitude of the steering speed Va is multiplied by a predetermined coefficient k, that is, an arithmetic expression The opening degree B of the flow control valve 16 is obtained using B = k · | Va | (step S4).
Next, if necessary according to the steering direction, the pair of paths 15 is switched between each other by the direction control valve 17 (steps S5 and S6), and the flow control valve 16 is set to the opening degree B obtained in step S4. The drive of the motor 20 is controlled (step S7), and the flow control valve 16 is closed with the end of the steering.
[0019]
On the other hand, when the steering speed Va obtained in step S2 is zero (actually, when it is in an error region near zero) (YES in step S3), steps S1 to S3 are repeated, and the steering speed is reduced. Continue monitoring Va.
According to the present embodiment, in the vehicle steering system 1 including the hydraulic power steering system, when the operation of the steering member 2 is started, the steering angle sensor 18 immediately detects the steering angle A, and accordingly, the steering angle A is detected. Since the steering speed Va is detected, and the hydraulic oil can be supplied / discharged to / from the hydraulic actuator 7 with a supply / discharge amount corresponding to the steering speed Va, the steering assist force can be generated without delay with good responsiveness. With a slight delay, the torsion bar 6 is twisted, and in response to this torsion, the pressure oil is also supplied via the control valve 10, and the steering assist is further complemented.
[0020]
In addition, when the steering speed Va is high, the flow speed of the working oil into the hydraulic actuator 7 can be increased, so that steering assistance with more responsiveness can be performed.
Next, FIG. 3 is a schematic cross-sectional view showing the overall configuration of a vehicle steering system according to another embodiment of the present invention. In the present embodiment, a description will be given based on the case of a steer-by-wire type vehicle steering system 1A using a hydraulic actuator for steering.
The mechanical coupling between the steering member 2 such as a steering wheel and the steering mechanism 4 is eliminated, and the steering shaft 4c is driven by the hydraulic pressure of a hydraulic actuator 7 as a steering actuator driven in response to, for example, a rotation operation of the steering member 2. Is moved in the axial direction to steer the steered wheels 11 for steering.
[0021]
The steering member 2 is connected to a steering shaft 30 rotatably supported by the vehicle. The steering shaft 30 is provided with a reaction force actuator 31 for applying an operation reaction force to the steering member 2. The reaction force actuator 31 includes an electric motor such as a brushless motor having an output shaft integrated with the steering shaft 30.
An elastic member 32 composed of a spiral spring or the like is connected to an end of the steering shaft 30 opposite to the steering member 2. The elastic member 32 causes the steering member 2 to return to the straight-ahead steering position by its elastic force when the reaction force actuator 31 does not apply torque to the steering member 2.
[0022]
In order to detect an operation input value of the steering member 2, a steering angle sensor 18 for detecting a steering angle of the steering member 2 is provided in association with the steering shaft 30. The steering shaft 30 is provided with a torque sensor 33 for detecting a torque applied to the steering member 2. On the other hand, a turning angle detection sensor 34 for detecting the turning angle of the steered wheels 11 is provided in association with the turning shaft 4c.
The steering angle sensor 18, the torque sensor 33, the turning angle sensor 34, and the vehicle speed sensor 35 are connected to the control unit 36.
[0023]
A flow control valve 16 for controlling the supply and discharge of hydraulic oil to and from the hydraulic actuator 7 and an electromagnetic directional control valve 17 are provided in a pair of paths 37 connecting the hydraulic passage 7 with the oil passage pump 8 and the oil tank 9. The control unit 36 controls the drive of the motor 20 for adjusting the opening of the flow control valve 16 via the drive circuit 21, and controls the switching of the direction control valve 17 via the drive circuit 22. Is similar to the embodiment of FIG. Further, the control unit 36 controls the reaction force actuator 31 via the drive circuit 38.
[0024]
FIG. 4 shows a flow of the steering control by the control unit 36. The control unit 36 reads the steering angle A detected by the steering angle sensor 18, the steering angle C detected by the steering angle sensor 34, and the vehicle speed R detected by the vehicle speed sensor 35 (step S1). The steering speed (steering angular speed) Va is obtained by differentiating the angle A (step S2).
When the steering speed Va is not zero (actually, when it deviates from the error region near zero) (NO in step S3), the arithmetic expression B = B1 (CA, R) + k · | Va | Then, the opening degree B of the flow control valve 16 is obtained (step S4).
[0025]
B1 (CA, R) is a deviation (CA) between the steering angle A detected by the steering angle sensor 18 and the steering angle C detected by the steering angle sensor 34, and detected by the vehicle speed sensor 35. The reference opening is set based on the vehicle speed R to be set. On the other hand, k · | Va | is a factor that increases as the magnitude of the steering speed Va increases.
Next, if necessary according to the steering direction, the pair of paths 37 are switched between each other by the direction control valve 17 (steps S5 and S6), and the flow control valve 16 is set to the opening degree B obtained in step S4. The drive of the motor 20 is controlled (step S7).
[0026]
Further, based on the detected steering angle A, the steering torque detected by the torque sensor 33, and the detected vehicle speed R, an appropriate reaction force in a direction opposite to the operation direction of the steering member 2 is generated. The driving of the reaction force actuator 31 is controlled via the drive circuit 38. The flow control valve 16 is closed with the end of the steering.
On the other hand, when the steering speed Va obtained in step S2 is zero (actually, when it is in an error region near zero) (YES in step S3), steps S1 to S3 are repeated, and the steering speed is reduced. Continue monitoring Va.
[0027]
In the present embodiment, in the steer-by-wire vehicle steering device 1A that obtains the steering force by the hydraulic actuator 7, when the operation of the steering member 2 is started, the steering angle sensor 18 immediately detects the steering angle A, With this, the steering speed Va is detected, and the hydraulic oil can be supplied / discharged to / from the hydraulic actuator 7 with a supply / discharge amount including an increment corresponding to the steering speed Va, so that there is no delay with respect to the operation of the steering member 2. Steering can be realized. In particular, when the steering speed Va is high, the flow speed of the hydraulic oil into the hydraulic actuator 7 can be increased, so that steering with more responsiveness can be performed.
[0028]
Further, by adding an increment k · | Va | depending on the steering speed Va to the above-mentioned reference opening B1 as the opening B of the flow control valve 16, a sufficient amount of supply / discharge to the hydraulic actuator 7 can be secured. Therefore, when the operation of the steering member 2 is stopped, the turning by the hydraulic actuator 7 ends without a time lag.
In the above embodiments, the flow control valve 16 and the motor 20 as the driving means are used, and the opening is increased in accordance with the increase in the steering speed Va. However, the present invention is not limited to this. For example, in the embodiment of FIG. 1, an electromagnetic on-off valve is used in place of the flow control valve 16, a solenoid is used in place of the motor 20 as a driving means, and when the steering speed Va is detected, the solenoid is turned on ( Or off) to open the on-off valve, and when the steering speed Va is not detected, the solenoid may be turned off (or on) to switch the on-off valve to the closed state. Also, the opening degree and the opening / closing time of the flow control valve can be controlled in accordance with the steering speed and the load to enable active steering.
[0029]
In addition, various changes can be made within the scope of the claims of the present invention.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a schematic configuration of a hydraulic power steering device as one embodiment of the present invention.
FIG. 2 is a flowchart illustrating a flow of steering control.
FIG. 3 is a schematic diagram showing a schematic configuration of a steer-by-wire type vehicle steering system as another embodiment of the present invention.
FIG. 4 is a flowchart showing a flow of steering control.
[Explanation of symbols]
1, 1A Vehicle steering device 2 Steering member 3 Input shaft 4 Steering mechanism 5 Output shaft 6 Torsion bar 7 Hydraulic actuator 8 Hydraulic pump 9 Oil tank 10 Control valve 11 Wheels 14, 15 Route 16 Flow control valve 17 Direction control valve 18 Steering Angle sensor 19 Control unit 20 Motor 31 Reaction force actuator 34 Steering angle sensor 35 Vehicle speed sensor 36 Control unit

Claims (2)

In a vehicle steering device that generates a steering force or a steering assist force by a hydraulic actuator according to an operation of a steering member,
A valve that controls the flow of hydraulic oil into and out of the hydraulic actuator,
Driving means for operating the valve;
Steering speed detection means for detecting a steering speed of the steering member,
Control means for controlling the operation of the valve via the drive means in accordance with the steering speed detected by the steering speed detection means. In claim 1, the valve comprises a flow control valve, and the control means controls the flow control valve such that the flow rate of the flow control valve increases as the steering speed detected by the steering speed detection means increases. A steering device for a vehicle.

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