JPH05124533A - Steering controller for vehicle - Google Patents

Abstract

PURPOSE:To provide a steering controller for a vehicle which can reduce the load of a driver in the steering operation. CONSTITUTION:A steering controller is constituted of a steering wheel 2, steering gear device 5 into which the revolution of the steering wheel 2 is inputted through a steering wheel shaft 3 and an intermediate shaft, tie rod 8 for steering the left and right steered wheels 6 and 6 by the output of the gear device 5, and so on. Between the steering wheel shaft 3 and the intermediate shaft 4, a steering gear ratio varying mechanism part 10 for varying the ratio between the turning angle of the steering wheel 2 and each steering angle of the wheels 6 and 6 is installed. Further, an actuator 7 for operating the steering gear ratio varying mechanism part 10 and an ECU 11 for controlling the actuator 7 are installed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering control device for controlling steering of a steering wheel.

[0002]

2. Description of the Related Art Conventionally, lateral acceleration and yaw rate are generated by turning a steering wheel provided in a vehicle.

[0003]

When driving such a vehicle, even if the driver steers the steering wheel at the same steering angle, the lateral acceleration and yaw rate generated by the vehicle speed are different (see FIG. 11). The vehicle may become unstable. In the past, the driver had to sensuously sense lateral acceleration and yaw rate to perform additional steering and return steering in order to avoid an unstable state of the vehicle. Therefore, there is a problem that not only the driver is required to get used to the vehicle and to have high skill, but also the steering operation itself becomes a heavy burden.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a steering control device for a vehicle, which can reduce the load of the driver's steering operation.

[0005]

In order to achieve the above object, a vehicle steering control device of the present invention comprises a vehicle speed detecting means for detecting a vehicle speed and a wheel steering angle for generating a wheel steering angle corresponding to a steering operation of a steering wheel. The gist of the present invention is to include a generating unit and a setting unit that changes the wheel steering angle according to the vehicle speed to set a state amount generated by a behavior change when the vehicle is turning to a predetermined condition.

Further, at this time, it is preferable to provide a limiting means for limiting the steering angle of the steering wheel to a predetermined value or less.

[0007]

With the above construction, by changing the wheel steering angle corresponding to the steering operation of the steering wheel according to the vehicle speed, the state quantity generated by the behavior change at the time of turning of the vehicle becomes independent of the vehicle speed. Therefore, in order to avoid the unstable state of the vehicle, the driver may steer the steering regardless of the vehicle speed, regardless of the vehicle speed.

[0008]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. As shown in FIG. 1, the steering control device 1 is
A steering handle 2, a snare ring gear device 5 in which rotation of the handle 2 is input via a handle shaft 3 and an intermediate shaft 4, and a tie rod for steering left and right steering wheels 6.6 by an output of the gear device 5. It is composed of 8 etc.

Between the handle shaft 3 and the intermediate shaft 4,
Steering gear ratio variable mechanism section for changing the ratio (steering gear ratio: N = θ / δ) of the rotation angle of the steering wheel 2 (steering angle: θ) and the steering angle of the wheels 6.6 (wheel steering angle: δ). 10 are provided.

An actuator 7 for operating the steering gear ratio variable mechanism portion 10 and an electronic control unit (hereinafter referred to as "ECU") 11 for controlling the actuator 7 are provided. This actuator 7
Specifically, an electric motor, a hydraulic motor, a hydraulic cylinder, a pneumatic cylinder or the like can be adopted. The ECU 11 includes a vehicle speed V from a vehicle speed sensor 12 that detects the vehicle speed of the vehicle.
And a signal S ₁ indicating

The structure of the skiring gear ratio variable mechanism section 10 is disclosed, for example, in Japanese Patent Laid-Open No. 63-240476. Here, the ECU 11 sets the steering gear ratio N according to the vehicle speed V indicated by the signal S ₁ from the vehicle speed sensor 12 based on a predetermined control map shown in FIG.
The drive signal S ₃ is output to the actuator 7 so that the steering gear ratio N set to 0 is obtained.

In this case, the reciprocal characteristic of the steering gear ratio N with respect to the vehicle speed V is set so that the reciprocal of the steering gear ratio N decreases as the vehicle speed V increases, and the relationship between the steering angle θ and the lateral acceleration G. Is uniquely determined regardless of the vehicle speed V. That is, by setting the steering gear ratio N according to the control map shown in FIG.
The characteristics shown in can be obtained.

Next, the control processing by the ECU 11 will be described with reference to the flowchart of FIG.
The vehicle speed V is read in, and then, in step S2, the target steering gear ratio corresponding to the vehicle speed V is calculated from the steering gear ratio control map (see FIG. 2). In step S3, the operation amount of the actuator 7 corresponding to the target steering gear ratio and the drive signal S ₄ output to the actuator 7 are output.
To calculate. In step S4, the drive signal S ₄ calculated in step S3 is output to the actuator 7.

By the above control, the steering gear ratio N changes according to the vehicle speed V. As a result, the same steering angle θ
However, since the wheel steering angle δ is different, the lateral acceleration G generated in the vehicle does not depend on the vehicle speed V, and the lateral acceleration G can be expressed by a function of only the steering angle θ. Therefore, the driver can very easily predict the proper steering angle at the time of turning. Further, if the driver uses the lateral acceleration G as feedback information, the steering angle θ
Since it can also be used as feedforward information, the judgment time and information transmission delay time can be shortened, the responsiveness of steering operation and controllability (positioning accuracy) are greatly improved, and the load on the driver is reduced. You can In addition, it is easy to predict the turning limit, so that safety can be improved.

In this embodiment, the vehicle speed sensor 1
2 corresponds to vehicle speed detecting means, the steering gear ratio variable mechanism section 10 corresponds to wheel steering angle detecting means, and the flowchart of FIG. 4 corresponds to setting means.

Next, a second embodiment will be described. First
In the embodiment, the lateral acceleration G generated in the vehicle is changed to the vehicle speed V by changing the steering gear ratio N according to the vehicle speed V.
The second embodiment is characterized in that the object is achieved by making the tire air pressure variable.

FIG. 5 is a schematic diagram showing the structure of the second embodiment. The configuration of the second embodiment is partly the same as that of the first embodiment, and the same components are designated by the same reference numerals and their description is omitted.

In FIG. 5, the tire characteristic variable actuator 14 has a pressure source and a tire pressure control valve as disclosed in, for example, Japanese Unexamined Patent Publication No. 2-169310, and a part of the wheel 6 is provided. By changing the air pressure of a certain tire 15, the lateral force characteristic of the tire 15 is changed. This tire characteristic variable actuator 14 is an ECU
Controlled by a signal from 13.

The ECU 13 sets the tire pressure in accordance with the vehicle speed V indicated by the signal S ₁ from the vehicle speed sensor 12 on the basis of a predetermined control map.
The drive signal S ₃ is output to the tire characteristic variable actuator 14 so that the air pressure of No. 5 becomes the set air pressure.

In this case, the air pressure characteristic of the tire 15 with respect to the vehicle speed V is set so that the air pressure increases as the vehicle speed V increases. As a result, the air pressure of the tire 15 is increased during high-speed traveling, and the lateral force generated by the tire 15, that is, the lateral acceleration G generated by steering is reduced. On the other hand, when the vehicle is traveling at a low speed, the air pressure of the tire 15 is lowered and the lateral acceleration G generated by steering is increased.
The lateral acceleration G generated is large even if the steering is made small.

Next, the control processing by the ECU 13 will be described with reference to the flowchart of FIG.
The vehicle speed V is read in 1 and then in step S12 the vehicle speed V is read.
The target air pressure of the tire 15 is calculated according to In step S13, the operation amount of the tire variable actuator 14 corresponding to the target air pressure calculated in step S12 and the drive signal S ₃ output to the tire variable actuator 14 are calculated. In step S14, the drive signal S ₃ calculated in step S13 is output to the tire variable actuator 14.

As a result, the air pressure of the tire 15 changes according to the vehicle speed V. Therefore, similarly to the first embodiment, it is possible to easily predict the appropriate steering angle at the time of turning, and at the same time, the responsiveness and controllability of the steering operation by the driver are greatly improved, and the steering load can be reduced.

In this embodiment, the vehicle speed sensor 1
2 corresponds to vehicle speed detecting means, the tire characteristic variable actuator 14 corresponds to wheel steering angle detecting means, and the flowchart of FIG. 6 corresponds to setting means.

Next, a third embodiment will be described. A part of the configuration of the third embodiment is also the same as that of the first embodiment, and the same components are designated by the same reference numerals and the description thereof will be omitted. 7 and 8 show the configuration of the third embodiment. FIG. 7 is the third
It is a schematic diagram showing the composition of an example, and Drawing 7 is an AA line sectional view of Drawing 8.

The steering angle sensor 17 detects the steering angle θ of the steering wheel 2 and outputs a steering angle signal S ₄ to the ECU 18
Output to. The steering angle limiting mechanism portion 16 is provided on a steering angle control pin 16b attached to the handle shaft 3, a plate 16c that is fixed to a vehicle body (not shown) and does not rotate, and a stopper 1 that can project in the direction of the handle shaft 3.
6d, a solenoid 16e for projecting the stopper 16d in the handle shaft 3 direction. And ECU
When the steering angle limiting mechanism 16 is driven by a signal from 18, the stopper 16d projects toward the handle shaft 3 as shown in FIG. 11, and the steering shaft 3 rotates so that the steering angle control pin 16b and the stopper 16d can come into contact with each other. It becomes a state. This prevents the steering wheel 2 from rotating more than θ _L from the neutral position. Here, θ _L is a limit steering angle at which the vehicle can travel stably, and is about 162 ° in this embodiment.

The ECU 18 determines the steering gear ratio N in accordance with the vehicle speed V indicated by the signal S ₁ from the vehicle speed sensor 12.
The driving signal S ₃ is output to the actuator 7 so that the steering variable mechanism section 10 has the set steering gear ratio N while the setting is made based on the predetermined control map shown in FIG. Further, it is determined whether or not the steering angle limiting mechanism unit 16 is driven according to the steering angle θ indicated by the signal S ₄ from the steering angle sensor 17.

Next, the control processing by the ECU 18 will be described with reference to the flowchart. The control process for the actuator 7 by the ECU 18 is as shown in FIG. 4 as in the first embodiment. Steering angle limiting mechanism unit 1 by the ECU 18
The control process for 6 is shown in FIG.

First, in step S21, the steering angle θ is read, and then in step S22, the steering angle θ is (θ _L -Δθ).
It is determined whether or not the above. If NO is determined in step S22, the control ends. On the other hand, if YES is determined in the step S22, the process proceeds to a step S23. In step S23, a drive signal is output to the steering angle limiting mechanism section 16. Then, the solenoid 16d of the steering angle limiting mechanism unit 16
The stopper 16c projects by being energized. As a result, the rotation of the handle shaft 3 is stopped, and the driver cannot steer the steering handle 2 from the neutral position over the steering angle θ _L.

As described above, in the third embodiment, in addition to the structure of the first embodiment, the steering angle sensor 17 and the steering angle limiting mechanism portion 16 for preventing the steering input exceeding the limit of the vehicle are provided. , The steering prohibition region where the driver is above the set angle θ _L from the neutral position of the steering wheel 2 (see FIG. 10)
Can not be steered, and accidents due to excessive steering can be prevented.

In the third embodiment described above, the steering angle limiting mechanism section 16 corresponds to the limiting means. The third embodiment may be configured such that the stopper 16c is always projected, instead of the stopper 16c being projected by the control of the ECU 18. In the case of this configuration, the steering angle sensor 17 can be omitted.

Although the first to third embodiments have been described above, the present invention is not limited to the above embodiments.
For example, various modifications can be made as follows without departing from the spirit of the invention.

In the control map shown in FIG. 2, the relationship between the steering angle θ and the yaw rate may be uniquely determined regardless of the vehicle speed V. In the first embodiment, the steering gear ratio variable mechanism section 10 may be a continuously variable transmission such as a CVT or a ring cone.

In the first embodiment, an auxiliary steering actuator, a steering angle sensor, a mechanism for transmitting the steering angle to the auxiliary steering actuator, etc. are provided instead of changing the steering gear ratio, and the auxiliary steering actuator assists the wheels. The same effect can be obtained by steering.

A wheel speed sensor, an engine speed sensor or the like may be used as the vehicle speed sensor. In the second embodiment, not only the tire air pressure but also the contact area with the road surface, wheel alignment, etc. may be changed.

[0035]

As described above in detail, according to the present invention, by changing the wheel steering angle corresponding to the steering operation of the steering wheel according to the vehicle speed, the state quantity generated by the behavior change at the time of turning of the vehicle is the vehicle speed. Irrelevant to Therefore, in order to avoid the unstable state of the vehicle, the driver can steer the steering regardless of the vehicle speed, regardless of the vehicle speed, and thus the driver's steering operation load is reduced. It has an excellent effect that it can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a first embodiment.

FIG. 2 is a steering gear ratio control map.

FIG. 3 is a characteristic diagram showing a relationship between a steering angle and a vehicle lateral acceleration.

FIG. 4 is a flowchart showing control processing by the ECU 11.

FIG. 5 is a schematic diagram showing a configuration of a second embodiment.

FIG. 6 is a flowchart showing a control process by the ECU 13.

FIG. 7 is a schematic diagram showing a configuration of a third exemplary embodiment.

8 is a cross-sectional view taken along the line AA of FIG.

FIG. 9 is a flowchart showing control processing by the ECU 18.

FIG. 10 is a characteristic diagram showing a relationship between a steering angle and a vehicle lateral acceleration.

FIG. 11 is a characteristic diagram showing a relationship between a steering angle and a vehicle lateral acceleration.

[Explanation of symbols]

 10 Steering Gear Ratio Variable Mechanism Unit 11 ECU 12 Vehicle Speed Sensor 13 ECU 14 Tire Property Variable Actuator 16 Steering Angle Limiting Mechanism Unit 18 ECU

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazunori Shimokawa 1-1-1, Showa-cho, Kariya city, Aichi Prefecture Nihondenso Co., Ltd.

Claims (2)

[Claims] 1. A vehicle speed detecting means for detecting a vehicle speed, a wheel steering angle generating means for generating a wheel steering angle commensurate with a steering operation of a steering wheel, and a vehicle by changing the wheel steering angle according to the vehicle speed. A steering control device for a vehicle, comprising: a setting unit that sets a state amount generated by a behavior change during turning to a predetermined condition. 2. The steering control device for a vehicle according to claim 1, further comprising: a limiting unit configured to limit a steering angle of the steering to a predetermined value or less.