JP2000085610A - Vehicle steering control device - Google Patents

Abstract

(57) Abstract: In a vehicle steering control device provided with a variable transmission ratio mechanism between a steering wheel and a steering gear mechanism, the transmission ratio is varied by rotationally driving a variable transmission ratio actuator, a variable transmission ratio mechanism is provided. It is an object of the present invention to provide a vehicle steering control device capable of locking a variable transmission ratio actuator in the event of a failure while maintaining a high positive efficiency. SOLUTION: In a vehicle steering control device provided with a transmission ratio variable mechanism for varying a transmission ratio by rotating a drive motor 25 between a steering wheel and a steering gear mechanism 42, a torque transmission system of the drive motor 25 is provided. And a control means 50 for controlling an operation state of the friction plate, and restricts rotation of the drive motor 25 by frictional force.

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 in which a transmission ratio of a wheel turning angle to a steering angle of a steering wheel is variable.

[0002]

2. Description of the Related Art Conventionally, in a vehicle steering control device,
In order to ensure running stability according to the vehicle speed, there is a device that employs a transmission ratio variable mechanism that changes a rotation transmission ratio (gear ratio) between an input and an output in a gear device according to the vehicle speed. Japanese Patent Application Laid-Open No. 62-214058 discloses a vehicle in which a transmission ratio variable means of a planetary gear type is interposed between a steering wheel and a steering gear mechanism, and the rotation of a ring gear is arbitrarily controlled to vary the transmission ratio characteristic. Steering control device is disclosed.

[0003] In this vehicle steering control device, a ring gear of a planetary gear mechanism is a worm wheel, and this worm wheel is meshed with a worm connected to a motor shaft to constitute a variable transmission ratio mechanism.

[0004]

By the way, in this device, it is necessary to reduce the reverse efficiency of the worm gear and provide the worm gear with a self-locking function in order to be able to steer when the variable transmission ratio system fails.

[0005] However, when the reverse efficiency of the worm gear is reduced, the normal efficiency is also reduced. Therefore, it is necessary to use a large-sized actuator for the variable gear system, and there is a problem in terms of mountability and cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle steering control device provided with a variable transmission ratio mechanism between a steering wheel and a steering gear mechanism, the transmission ratio being varied by rotationally driving a variable transmission ratio actuator. It is an object of the present invention to provide a vehicle steering control device capable of locking a variable transmission ratio actuator in the event of a failure while maintaining a high positive efficiency.

[0007]

According to a first aspect of the present invention, there is provided a vehicle steering control device including a variable transmission ratio mechanism for varying a transmission ratio between a steering wheel and a steering gear mechanism by rotationally driving a variable transmission ratio actuator. A steering control device for a vehicle, comprising: a rotation limiting force applying unit disposed in a torque transmitting system of the variable transmission ratio actuator; and a control unit for controlling an operation state of the rotation limiting force applying unit. And

According to the vehicle steering control device of the first aspect, by providing the rotation limiting force applying means for limiting the rotation of the variable transmission ratio actuator for driving the variable transmission ratio mechanism, for example, the variable transmission ratio Since the variable transmission ratio actuator can be fixed as necessary, for example, when the mechanism fails, the reverse efficiency of the gear mechanism at the connection between the variable transmission ratio actuator and the variable transmission ratio mechanism can be increased.
Accordingly, the positive efficiency also increases, so that the transmission ratio variable actuator can be reduced in size.

According to a second aspect of the present invention, in the vehicle steering control device according to the first aspect of the present invention, the rotation limiting force applying means transmits the driving force of the transmission ratio variable actuator to the transmission ratio variable mechanism. It is characterized in that it is a frictional force applying means arranged in the middle of the transmission system for transmitting.

According to the vehicle steering control device of the second aspect, the frictional force disposed in the transmission system for transmitting the driving force of the variable transmission ratio actuator to the variable transmission ratio mechanism by the rotation limiting force applying means. Since the transmission means is configured as the provision means, the variable transmission ratio actuator can be fixed as required with a simple configuration, so that the reverse efficiency in the gear mechanism can be increased. Further, at the time of excessive input, the frictional force applying means permits rotation as a torque limiter, so that protection of the system can be achieved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a vehicle steering control device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a vehicle steering control device according to an embodiment of the present invention. The upper end of the input shaft 10 is connected to a steering shaft, and a steering handle (not shown) is connected to the steering shaft. For this reason, the input shaft 10 has a mechanism that rotates in the same direction as the steering wheel.

The input shaft 10 penetrates through a cylindrical sleeve body 20. The sleeve body 20 forms an annular sun gear 21 at one end of a sleeve 22, and an annular worm wheel at the other end. 23 are formed and integrated, and are arranged concentrically with respect to the input shaft 10. A bearing 12 is interposed between the outer peripheral portion of the input shaft 10 and the inner peripheral portion of the sleeve body 20, and the input shaft 10 and the sleeve body 20 rotate independently without being restricted from rotating. Mechanism.

A disc-shaped carrier 11 having an outer diameter larger than that of the sun gear 21 is fixed to a penetrating end of the input shaft 10 penetrating the sleeve body 20. This carrier 1
Support pins 13 are fixed at three places at equal intervals on the peripheral edge of 1, and each support pin 13 rotatably supports a planetary gear 30. These three planetary gears 30 include a sun gear 21 located at the center.
When the carrier 11 rotates integrally with the input shaft 10, the planetary gears 30 rotate around the sun gear 21 while meshing with the sun gear 21.

An annular ring gear 40 is provided so as to surround each planetary gear 30, and gear teeth formed on the inner peripheral portion of the ring gear 40
0 is engaged. Therefore, as shown in FIG. 2, the sun gear 21, the planetary gear 30 and the ring gear 40 are arranged concentrically, and the sun gear 21 and each planetary gear 30
Are in mesh with each other, and each planetary gear 30 and the ring gear 40 are in mesh with each other, and constitute a planetary gear mechanism.

An output shaft 41 is integrated with the ring gear 40, and a rack shaft 43 is engaged with a pinion 42 formed on the output shaft 41. With such a rack and pinion mechanism, the rotational movement of the output shaft 41 is controlled by the rack shaft 4.
3 to convert the linear motion to steer the wheels. On the other hand, a worm gear 24 meshes with a worm wheel 23 that forms the sleeve body 20, and the worm gear 24 is a mechanism that is driven to rotate by a drive motor 25 (see FIG. 3).

As shown in FIG. 4, the drive motor 25 is fixed to the housing 2. A friction plate 26 having a disc shape is provided on the rotating shaft of the drive motor 25.
And is fixed at a predetermined distance from the outer wall of the main body. Further, a coil 27 is wound concentrically around the rotation axis of the drive motor 25, and one end of the coil 27 is arranged in contact with the inner wall surface of the housing.

The electronic control unit (ECU) 50 controls the rotation of the drive motor 25 in accordance with the steering direction and the vehicle speed based on the detection results of the vehicle speed sensor 60 and the steering angle sensor 61, and controls the rotation in accordance with the vehicle speed. The wheels are steered according to the gear ratio. When a failure of the variable transmission ratio mechanism or the like is detected, a process for fixing the worm gear 24 and the housing 2 is performed. That is, when the difference between the target pinion angle and the turning angle determined based on the vehicle speed or the like is equal to or larger than a predetermined value, or when the current is not supplied to the drive motor 25 despite the steering operation, the variable gear If it is determined that the system is in a failure state, the coil 27 is energized to draw the friction plate 26 toward the outer wall of the housing 2 and the worm gear 24 is fixed by the frictional force between the friction plate 26 and the outer wall of the housing 2. (See FIG. 5).

Therefore, according to the vehicle steering control device, the rotation of the drive motor 25 can be restricted as necessary by the friction plate 26 when the transmission ratio variable mechanism is out of order. The steering wheel can be steered even at times. Further, since the reverse efficiency of the worm gear at the connecting portion between the drive motor 25 and the variable transmission ratio mechanism can be increased, the drive motor 25 can be reduced in size, and the vehicle mountability can be improved and the cost can be reduced. Reduction can be realized. Further, when there is an excessive input from a steering wheel or the like, the friction plate 26 is allowed to rotate as a torque limiter, thereby protecting the system.

In the above-described embodiment, the rotation of the worm gear is restricted by using the friction plate 26. However, the rotation of the worm gear may be restricted by using the holding torque of the drive motor 25. Good. For example, when a worm gear having a gear ratio of 20 and a reverse efficiency of 10% is used, the lock torque at the time of failure of the variable gear system is 60 N.
If more than m is required, this variable gear system requires a lock torque of 20 Nm or more. Here, assuming that a stepping motor having a holding torque X or more is used as a drive motor, lock torque = gear ratio × (1 / efficiency)
By setting the holding torque of X = 0.1 Nm or more in the stepping motor from the relationship of × the holding torque of the motor, the rotation of the worm gear can be limited by using the holding torque of the stepping motor when the variable gear system fails. . In this case, when an excessive input of 60 Nm or more is input from the steering wheel, the stepping motor rotates as functioning as a torque limiter, thereby protecting the system.

In the above-described embodiment, the coils 27 are arranged concentrically about the rotation axis of the drive motor 25.
Is wound, and one end of the coil 27 is disposed in contact with the inner wall surface of the housing. A plurality of coils are concentrically arranged around the rotation axis of the drive motor 25, and the plurality of coils are May be arranged in a state where one end of each of them contacts the inner wall surface of the housing.

[0021]

According to the first aspect of the present invention, the rotation limiting force applying means for limiting the rotation force of the variable transmission ratio actuator for driving the variable transmission ratio mechanism is provided. Since the variable transmission ratio actuator can be fixed as necessary, for example, in the event of a failure, the reverse efficiency of the gear mechanism at the connection between the variable transmission ratio actuator and the variable transmission ratio mechanism can be increased. Accordingly, the positive efficiency also increases, so that the transmission ratio variable actuator can be reduced in size.

According to the second aspect of the present invention, the rotation limiting force applying means is provided as a frictional force applying means disposed in the transmission system for transmitting the driving force of the variable transmission ratio actuator to the variable transmission ratio mechanism. With this configuration, the variable transmission ratio actuator can be fixed as required with a simple configuration, so that the reverse efficiency of the gear mechanism can be increased. Further, at the time of excessive input, the frictional force applying means permits rotation as a torque limiter, so that protection of the system can be achieved.

[Brief description of the drawings]

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

FIG. 2 is a plan view showing only a planetary gear mechanism in the vehicle steering control device according to the embodiment of the present invention;

FIG. 3 is a schematic diagram showing a main part of a vehicle steering control device according to an embodiment of the present invention.

FIG. 4 is a diagram showing a structure for fixing a drive motor according to the embodiment of the present invention.

FIG. 5 is a view showing a fixed state of the drive motor according to the embodiment of the present invention.

[Explanation of symbols]

10 input shaft, 11 carrier, 20 sleeve body, 2
DESCRIPTION OF SYMBOLS 1 ... Sun gear, 23 ... Worm wheel, 24 ... Worm gear, 25 ... Drive motor, 26 ... Friction plate, 27 ... Coil, 30 ... Planetary gear, 40 ... Ring gear, 41 ...
Output shaft.

Claims (2)

[Claims] 1. A vehicle steering control device comprising a variable transmission ratio mechanism that varies a transmission ratio by rotating a variable transmission ratio actuator between a steering wheel and a steering gear mechanism. A steering control device for a vehicle, comprising: a rotation limiting force applying unit disposed in a transmission system; and a control unit for controlling an operation state of the rotation limiting force applying unit. 2. The rotation limiting force applying means is a frictional force applying means arranged in a transmission system for transmitting a driving force of the variable transmission ratio actuator to the variable transmission ratio mechanism. The vehicle steering control device according to claim 1.