JP2001301639A - Steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To flexibly cope with the change of a steering characteristic according to a travel state without complicating the system of a steering device for a vehicle. SOLUTION: When the vehicle is judged to be normally running, a first electromagnetic clutch 5 is set to a disengaged state, and a second electromagnetic clutch 7 is set to an engaged state. The present travel state, i.e., the steering ratio optimum to a vehicle speed V, is determined based on the relation between the vehicle speed V and the steering gear ratio. A first drive motor 11 generates steering force, and a second drive motor generates steering reaction to realize a target steering angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering system in which steering means such as a steering wheel and a steering mechanism such as a rack and pinion type steering are not mechanically connected.

[0002]

2. Description of the Related Art Such a vehicle steering apparatus is disclosed, for example, in Japanese Patent Application Laid-Open No. Hei 10-218000, and corresponds to the relationship between the amount of operation of a steering means and the amount of operation of a steering mechanism without mechanical restrictions. Since the relationship can be set, it is possible to flexibly respond to changes in the steering characteristics according to the running state of the vehicle such as the speed of the vehicle, and other steering means such as levers and pedals can be employed instead of the steering wheel. In addition, there is an advantage that the degree of freedom in design is improved.

[0003] The vehicle steering apparatus disclosed in Japanese Patent Application Laid-Open No. 10-218000 has a steering angle sensor and a tie rod displacement sensor, and a main steering motor and a sub steering motor are arranged at different positions of a steering mechanism. The required steering force is determined based on the deviation between the steering wheel operating position detected by the steering angle sensor and the actual operating position of the steering mechanism detected by the tie rod displacement sensor, and the steering force is distributed to a predetermined ratio. Then, the main steering motor and the sub steering motor are driven and controlled, and the resultant is applied to the steering mechanism to perform steering. Further, when one of these motors fails, the output of the failed motor is stopped, and the distribution ratio is changed so as to increase the output of the non-failed motor to secure the steering force.

[0004]

However, in the vehicle steering apparatus disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 10-218000, the main steering motor and the sub-steering motor are driven by distributing necessary steering forces at a predetermined ratio. Control, the increase in the number of motors complicates the system,
There are various inconveniences such as a decrease in control reliability and an increase in cost. In addition, when one of the motors fails, the other motor generates a sufficient steering force, so that in order to ensure reliability in this state, the output per motor should be sufficient. Need
As a result, each motor must be relatively large, and it is not easy to arrange such motors in pairs.

In addition, this type of vehicle steering system can: (1) be suitable without increasing the size of the vehicle steering system even when the load on the driving means is large, such as when the steering amount is increased at an extremely low speed. To generate a strong steering force. (2) To prevent difficulty in steering when all the driving means are out of order. (3) To appropriately determine the failure of the driving means. (4) To prevent deterioration of the steering feeling such as a steering reaction force drop. (5) To facilitate the configuration and / or control of parts included in the vehicle steering system. (6) To improve the degree of freedom in mounting the vehicle steering system on the vehicle. Is preferred.

The vehicle steering apparatus according to the first aspect can flexibly cope with a change in the steering characteristic according to the traveling state without having the above-mentioned inconvenience, and can operate the second drive even if the first drive means breaks down. It is an object of the present invention to generate a steering force by means so as not to impair the function of a steering device of a vehicle.

A second object of the present invention is to set an appropriate steering force during normal running and / or when the first drive means fails.

A third aspect of the present invention is directed to a vehicle steering system that generates a relatively large steering force without increasing the size of the vehicle steering system even when the load on the first driving means is large. It is.

A fourth object of the present invention is to set an appropriate steering force when the load on the first drive means is large.

A fifth aspect of the present invention is directed to a steering apparatus for a vehicle, which prevents the steering from becoming difficult when the first and second driving means are out of order.

An object of the present invention is to appropriately determine a failure of the first drive means.

A further object of the present invention is to provide a vehicle steering system that appropriately determines a failure of the second drive means.

An object of the present invention is to determine the failure of the first and second drive means more appropriately.

The object of the present invention is to prevent the steering feeling from being deteriorated such as a steering reaction force loss even when the second driving means generates a steering force.

According to a tenth aspect of the present invention, there is provided a vehicle steering system comprising:
It is another object of the present invention to facilitate control of the second connecting and disconnecting means.

The vehicle steering system according to the eleventh aspect is characterized in that:
And to facilitate the configuration and control of the second drive means.

According to a twelfth aspect of the present invention, it is an object of the present invention to improve the degree of freedom in mounting the vehicle steering device on the vehicle.

[0018]

According to a first aspect of the present invention, there is provided a vehicle steering system comprising: a first shaft having one end associated with a steering mechanism;
A second connecting one end to a steering means for performing a steering operation by a driver;
A shaft, a third shaft disposed between the first shaft and the second shaft, a steering amount detecting unit for detecting a steering amount of the steering unit, and a running state detecting unit for detecting a running state of the vehicle. A control means for issuing a command based on the steering amount and / or the running state; and a first means for mechanically connecting and disconnecting the other end of the first shaft and one end of the third shaft in accordance with the command. Connecting and disconnecting means; second connecting and disconnecting means for performing mechanical connection and disconnection between the other end of the third shaft and the other end of the second shaft in accordance with the instruction; First driving means for generating a steering force according to the command, and second driving means mechanically connected to the third shaft for generating a steering reaction force or a steering force according to the command. For example, if said travel like is normal running is determined by the control means, said first connection and disconnection means, the other end and a third of said first shaft
The one end of the shaft is mechanically disconnected, the second connection and disconnection means mechanically connects the other end of the third shaft and the other end of the second shaft, and the first driving means controls the steering force. And when the control means determines that the second drive means generates a steering reaction force and the first drive means has failed, the first connection and disconnection means sets Mechanically connecting the other end of the first shaft to one end of the third shaft, and the second connecting and disconnecting means mechanically disconnects the other end of the third shaft from the other end of the second shaft; The second drive means is configured to generate a steering force.

According to a second aspect of the present invention, in the vehicle steering apparatus, the first driving means generates a steering force such that a value obtained by dividing the steering amount by a steering gear ratio according to the traveling state becomes a wheel angle. It is characterized by having such a configuration.

According to a third aspect of the present invention, when the control unit determines that the traveling state is an extremely low speed traveling and the steering amount is larger than a predetermined value, the first connection is established. And disconnection means mechanically connects the other end of the first shaft and one end of the third shaft, and the second connection and disconnection means connects the other end of the third shaft and the other end of the second shaft. Are mechanically separated from each other, so that the first and second driving means both generate a steering force.

According to a fourth aspect of the present invention, in the vehicle steering system, both the first and second driving means generate a steering force such that a value obtained by dividing the steering amount by a predetermined steering gear ratio becomes a wheel angle. It is characterized by having such a configuration.

According to a fifth aspect of the present invention, when the control means determines that both the first and second drive means are out of order, the first connection and disconnection means sets the first connection and disconnection means in the vehicle. The other end of the first shaft and one end of the third shaft are mechanically connected, and the second connection / disconnection means mechanically connects the other end of the third shaft and the other end of the second shaft. And the first driving means and the second driving means are stopped.

According to a sixth aspect of the present invention, in the vehicle steering system, the first connection and disconnection means mechanically disconnects the other end of the first shaft and one end of the third shaft, and the second connection and disconnection. When the target wheel angle is significantly different from the actual wheel angle when the means mechanically connects the other end of the third shaft and the other end of the second shaft, the first drive means fails. Is determined by the control means.

According to a seventh aspect of the present invention, in the vehicle steering system, the first connecting and disconnecting means mechanically connects the other end of the first shaft and one end of the third shaft, and the second connecting and disconnecting means. If the target wheel angle is significantly different from the actual wheel angle while the disconnecting means is mechanically disconnecting the other end of the third shaft and the other end of the second shaft, the second driving means fails. Is determined by the control means.

According to an eighth aspect of the present invention, in the vehicle steering apparatus, the target wheel speed is converted from the steering amount and the traveling state.

According to a ninth aspect of the present invention, in the vehicle steering system, the second connecting / disconnecting means generates a steering reaction force when the other end of the third shaft is mechanically disconnected from the other end of the second shaft. It is characterized by having an elastic member to make it.

According to a tenth aspect of the present invention, when the first and second connection / disconnection means are supplied with electric current, respectively, the other end of the first shaft and one end of the third shaft and When the other end of the third shaft is mechanically connected to the other end of the second shaft and no current is supplied, the other end of the first shaft, one end of the third shaft, and the third shaft And the other end of the second shaft is mechanically cut off.

According to a eleventh aspect of the present invention, in the vehicle steering system, the first drive means includes a gear mechanically connected to the first shaft, and a motor for transmitting a steering force to the first shaft via the gear. And the second driving means is provided in the third
It has a gear mechanically connected to a shaft, and a motor for transmitting a steering reaction force or a steering force to the third shaft via the gear.

According to a twelfth aspect of the present invention, at least one of the first to third shafts has a portion made of a flexible material.

[0030]

According to the vehicle steering system of the first aspect, when the control means determines that the running state is the normal running, the first connecting / disconnecting means connects the other end of the first shaft to the other end of the first shaft. While mechanically disconnecting one end of the third shaft, the second connecting and disconnecting means mechanically connects the other end of the third shaft and the other end of the second shaft,
The driving means generates a steering force, and the second driving means generates a steering reaction force. By generating the steering force by using a single driving means in this way, the steering characteristics can be changed according to the traveling state without the disadvantages caused by using two control means, that is, two motors. Can respond flexibly.

When the control means determines that the first drive means has failed, the first connection / disconnection means mechanically connects the other end of the first shaft to one end of the third shaft. At the same time, the second coupling and disconnecting means mechanically disconnects the other end of the third shaft from the other end of the second shaft, and the second driving means generates a steering force.
Thus, even if the first drive unit fails, the second drive unit
Since the steering force is generated by the driving means, the function of the steering device of the vehicle is not impaired.

According to the vehicle steering apparatus of the second aspect,
The first driving means generates a steering force such that a value obtained by dividing a steering amount by a steering gear ratio according to a traveling state becomes a wheel angle. As a result, an appropriate steering force can be set.

According to the vehicle steering apparatus of the third aspect,
When the control unit determines that the traveling state is the extremely low-speed traveling and the steering amount is larger than the predetermined value, the first connection / disconnection unit connects the other end of the first shaft to the third shaft.
While one end of the shaft is mechanically connected, the second connecting and disconnecting means mechanically disconnects the other end of the third shaft and the other end of the second shaft, and the first and second driving means are both steered. Generate force. When the load on the first driving unit is large by generating the steering force also in this manner, for example, a steering force larger than the steering force that can be generated by the first driving unit is required. Even in this case, a relatively large steering force can be generated without providing another driving means, that is, without increasing the size of the steering device of the vehicle.

According to the vehicle steering apparatus of the fourth aspect,
When the traveling state is extremely low-speed traveling and the control means determines that the steering amount is larger than the predetermined value, the wheel angle is obtained by dividing the steering amount by the predetermined steering gear ratio to obtain the wheel angle. The first and second driving means both generate a steering force. An appropriate steering force can be set when the load on the first drive unit is large.

According to the vehicle steering apparatus of the fifth aspect,
If the control means determines that both the first and second drive means have failed, the first connection and disconnection means mechanically connects the other end of the first shaft and one end of the third shaft. With the second connecting and disconnecting means,
The other end of the third shaft and the other end of the second shaft are mechanically connected, and the first driving means and the second driving means are stopped. As a result, the steering means and the steering mechanism are connected to each other, thereby preventing the steering from becoming difficult.

According to the vehicle steering system of the sixth aspect,
First connecting and disconnecting means mechanically disconnects the other end of the first shaft and one end of the third shaft,
If the connecting and disconnecting means mechanically connects the other end of the third shaft and the other end of the second shaft and the target wheel angle is significantly different from the actual wheel angle, the first driving means fails. Is determined by the control means. Thus, it is possible to appropriately determine the failure of the first drive unit.

According to the vehicle steering system of the seventh aspect,
First connecting and disconnecting means mechanically connects the other end of the first shaft and one end of the third shaft,
If the target wheel angle is significantly different from the actual wheel angle while the connecting and disconnecting means mechanically disconnects the other end of the third shaft and the other end of the second shaft, the second driving means fails. Is determined by the control means. Thus, it is possible to appropriately determine the failure of the second driving unit.

According to the vehicle steering system of the eighth aspect,
The target wheel speed is converted from the steering amount and the running state. Thereby, the failure of the first and second driving means can be more appropriately determined.

According to the vehicle steering system of the ninth aspect,
The second connection / disconnection means has an elastic member that generates a steering reaction force when mechanically disconnecting the other end of the third shaft from the other end of the second shaft. Since a steering reaction force is mechanically generated by such an elastic member such as a spring element,
Even if the first or second drive means breaks down, it is possible to prevent a deterioration in steering feeling such as a steering reaction force loss.

According to the vehicle steering system of the tenth aspect, when the first and second connecting and disconnecting means are supplied with electric current, respectively, the other end of the first shaft and one end of the third shaft and When the other end of the third shaft is mechanically connected to the other end of the second shaft, and no current is supplied, the other end of the first shaft, one end of the third shaft, and the other end of the third shaft And the other end of the second shaft is mechanically separated. In order to mechanically connect the steering means and the steering mechanism when the steering device of the vehicle is out of order, it is sufficient to prevent the current from flowing, so that the first and second connection and disconnection means can be easily controlled.

According to the vehicle steering system of the eleventh aspect, the first drive means includes: a gear mechanically connected to the first shaft; and a motor for transmitting a steering force to the first shaft via the gear. The second drive means includes a gear mechanically connected to the third shaft, and a motor for transmitting a steering reaction force or a steering force to the third shaft via the gear. Thereby, the configuration and control of the first and second driving means can be facilitated.

According to the vehicle steering apparatus of the twelfth aspect, at least one of the first to third shafts has a portion made of a flexible material. As a result, the degree of freedom in mounting the steering device of the vehicle on the vehicle can be improved. Note that all of the first, second, and / or third shafts may be made of a flexible material.

[0043]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of a vehicle steering system according to the present invention. One end of a first steering shaft 1 as a first shaft of the vehicle steering system forms a pinion shaft 2a of a rack and pinion type steering 2 as a steering mechanism, and a rack 2b
To the steering links 3a, 3
The wheels 4a and 4b are steered via the wheel b.

The other end of the first steering shaft 1 is mechanically connected and disconnected from one end of a second steering shaft 6 as a third shaft via a first electromagnetic clutch 5 as first connecting and disconnecting means. . The other end of the second steering shaft 6 is mechanically connected to and disconnected from one end of a third steering shaft 8 as a second shaft via a second electromagnetic clutch 7 as a second connecting and disconnecting means. A steering wheel 9 as steering means is connected to the other end of the third steering shaft 8.

The steering force generated by the first drive motor 11 is transmitted to the first steering shaft 1 via a mechanically connected gear 10, and the second steering shaft 6 is mechanically connected to the first steering shaft 1. The steering reaction force or the steering force generated by the second drive motor 13 is transmitted via the connected gear 12. The gear 10 and the first drive motor 11 constitute at least a part of a first drive unit, and the gear 12 and the second drive motor 13 constitute at least a part of a second drive unit. In addition, the first and second drive motors 1
1 and 13 are the rotation angles θ1 and θ2 of the first steering shaft 1 and the second steering shaft 6, respectively.
Encoders 11a and 13a as steering amount detecting means for detecting the steering angle. Further, the third steering shaft 8 is provided with a steering angle sensor 14 as a steering amount detecting means for detecting the rotation angle θ3 of the steering wheel 9.

The detected rotation angles θ1, θ2 and / or θ3 are supplied to an execution control unit (ECU) 16 together with the vehicle speed V from a vehicle speed sensor 15 as running state detecting means. The vehicle speed sensor is, for example, a rotation speed sensor that detects the rotation speed of a front wheel or a rear wheel corresponding to the vehicle speed.
The ECU 15 determines the rotation angles θ1, θ2 and / or θ
3 and the vehicle speed V, the result of performing the control described below is used as a command value as the first clutch 5, the second clutch 7,
This is transmitted to the first drive motor 11 and the second drive motor 13, respectively.

FIG. 2 is a cross-sectional view of the clutch shown in FIG. 1 when the clutch is engaged, and FIG. 3 is a cross-sectional view of the clutch shown in FIG. Hereinafter, the first electromagnetic clutch 5 will be described, but the configuration and operation of the second electromagnetic clutch 7 are the same as those of the first clutch 5.

The end 20 on the second steering shaft 6 side
, Disk-shaped members 21a and 21b are arranged. On the other hand, the end 22 on the first steering shaft 1 side has
A member 25 that rotates around the electromagnet 24 via the bearings 23a and 23b is arranged. The member 26 supporting the electromagnet 24 is fixed to a vehicle body (not shown) or the like. Member 2
5 is provided with a plurality of protrusions 26 extending in the same direction as the axial direction of the first and second steering shafts 1 and 6, and the disc-like member 2 movable along the protrusions 26 is provided.
7, 28 are provided. At the end of the projection 26, the disc-shaped member 29 is connected by a bolt 30.

The disk-shaped members 21a and 21b are provided between the disk-shaped member 27 and the disk-shaped member 28 and the disk-shaped member 2 respectively.
8 and the disk-shaped member 29, and are located between the disk-shaped members 27, 28, and 29.
, The friction material 31a, 31b, 31c,
31d are arranged respectively. The member 25 is provided with a coil spring 32 so as to generate an elastic force in the axial direction of the first and second steering shafts 1 and 6.

Here, the operation of the first electromagnetic clutch 5 will be described. When no current flows through the electromagnet 24, the disc-shaped member 27 receives a force in the direction of the second steering shaft 6 by the coil spring 32. With this force, the disc-shaped members 21a and 21b respectively move the friction members 31a and 31b and the friction members 31c and 31c between the disc-shaped member 27 and the disc-shaped member 28 and between the disc-shaped member 28 and the disc-shaped member 29, respectively. 31d
The first steering shaft 1 and the second steering shaft 6 are brought into a mechanically connected state by the frictional force as shown in FIG.

On the other hand, when a current is flowing through the electromagnet 24, a force stronger than the elastic force of the coil spring 32 acts on the disc-shaped member 27 in the direction of the first steering shaft 1, and the disc-shaped member 27 It is sucked to the member 24. As a result, the disc-shaped members 21a and 21b are moved between the disc-shaped member 27 and the disc-shaped member 28 and the disc-shaped member 2 respectively.
A slight gap is generated between the disk member 8 and the disc-shaped member 29, and the frictional force generated by the friction members 31a, 31b and 31c, 31d is not generated. As a result, the first steering shaft 1 and the second steering shaft 6 are in a mechanically separated state as shown in FIG. Thus, the electromagnet 24
The control of the first electromagnetic clutch 5 is facilitated by the presence or absence of the current flowing through the first electromagnetic clutch 5.

The operation of the first embodiment will be described. FIG.
5 is a flowchart showing the operation of the first embodiment. The ECU 16 repeatedly executes this routine by, for example, a periodic interruption every 10 ms. First, in step S11, the ECU 16 reads the current vehicle speed V and the steering angle θ from the vehicle speed sensor 15 and at least one of the encoders 11a and 13a and the steering angle sensor 14. Note that the steering angle θ is the rotation angle θ1 to θ
3 is optional.

Next, in step S12, it is determined whether the read vehicle speed V is lower than a predetermined value V0. In this step, it is determined whether or not the traveling state is the extremely low speed traveling, and the predetermined value V0 can be arbitrarily determined according to the design.

If the vehicle speed V is smaller than the predetermined value V0, in step S13, the absolute value of the steering angle .theta.
It is determined whether it is greater than zero. This step
This is for determining whether or not the amount of steering by the driver is large, and the predetermined value θ0 can be arbitrarily determined according to the design.

When the vehicle speed V is equal to or higher than the predetermined value V0, and when the absolute value of the steering angle θ is lower than the predetermined value θ0 even when the vehicle speed V is lower than the predetermined value V0, the vehicle is normally running. When it is determined that there is, the first electromagnetic clutch 5 is disengaged and the second electromagnetic clutch 7 is engaged (step S14), and the optimum steering gear ratio for the current running state, that is, the vehicle speed V is indicated by a solid line in FIG. FIG. 6A shows a determination based on the relationship between the indicated vehicle speed V and the steering gear ratio (step S15) and a target steering angle (ie, a target wheel speed converted from the steering angle θ and the vehicle speed V). Based on such Map1, the first drive motor 11 generates a turning force, and the second drive motor generates a turning reaction force (step 16).

Next, the ECU 16 detects the absolute value of the deviation between the resulting actual steering angle (ie, the value obtained by dividing the steering angle θ by the steering gear ratio corresponding to the vehicle speed) and the target steering angle, It is determined whether the value is larger than a predetermined value δ0 (step S17). This step is for determining whether or not the first drive motor 11 has failed, and the predetermined value δ0 can be arbitrarily determined according to the design. If the absolute value of the deviation is not larger than the predetermined value δ0, it is determined that the first drive motor 11 has not failed, and this routine ends. Thereby, without having the disadvantages caused by using two motors,
It is possible to flexibly cope with a change in the steering characteristics according to the running state.

On the other hand, the absolute value of the deviation is a predetermined value δ
If it is larger than 0, it is determined that the first drive motor 11 has failed, and the process proceeds to the next stage. That is, the first electromagnetic clutch 5 is engaged and the second electromagnetic clutch 7 is disengaged (step S18), and the optimum steering gear ratio for the current running state, that is, the vehicle speed V is shown by the solid line in FIG. The first drive motor 11 is determined based on the relationship between V and the steering gear ratio (step S19), based on Map1 as shown in FIG. The drive motor generates a turning force (step 20).

Next, in order to notify that the first drive motor 11 has failed, for example, the display of WARNING1 is turned on (step S21), and the ECU 16 determines the deviation between the resulting actual steering angle and the target steering angle. Is detected, and it is determined whether the value is greater than a predetermined value δ0 (step S22). This step is for determining whether or not the second drive motor 13 has failed. If the absolute value of the deviation is not larger than the predetermined value δ0, the second drive motor 13 has not failed. Is determined, and this routine ends. Thus, even when the first drive motor 11 fails, the steering force is generated by the second drive motor 13, so that the function of the steering device of the vehicle is not impaired.

On the other hand, the absolute value of the deviation is a predetermined value δ
If it is larger than 0, it is determined that the second drive motor 13 has also failed, and the state shifts to the mechanical backup state. That is, the first electromagnetic clutch 5 and the second electromagnetic clutch 7 are both connected (step S23), and the first drive motor 1
The first and second drive motors 13 are both stopped (step S2).
4) In order to notify that the second drive motor 11 has failed, for example, the display of WARNING2 is turned on (step S25), and this routine ends. As a result, the steering wheel 9 and the rack and pinion type steering 2 are connected to each other, thereby preventing the steering from becoming difficult.

In step S13, when the absolute value of the steering angle θ is larger than the predetermined value θ0, that is, when the vehicle is traveling at an extremely low speed and the steering angle is relatively large, the first electromagnetic clutch 5 is connected. Then, the second electromagnetic clutch 7 is disengaged (step S26), and the optimum steering gear ratio for the current running state, that is, the vehicle speed V is determined based on the relationship between the vehicle speed V and the steering gear ratio indicated by the broken line in FIG. (Step S27), and a map as shown in FIG.
2, the first drive motor 11 generates a steering force, and the second drive motor generates a steering force when the steering angle is smaller than a predetermined value, and the steering angle is larger than the predetermined value. In this case, a steering reaction force is generated (step 28). Note that the steering gear ratio determined in step S27 is constant irrespective of the vehicle speed V as shown by the broken line in FIG.

Next, the ECU 16 detects the absolute value of the resulting deviation between the actual steering angle and the target steering angle, and determines whether or not the value is greater than a predetermined value δ0 (step S2).
9). This step is for determining whether or not the steering device of the vehicle is malfunctioning. If the absolute value of the deviation is not larger than the predetermined value δ0, it is determined that the steering device of the vehicle is not malfunctioning. Then, this routine ends. By generating the steering force by the second drive motor in this manner, even when a steering force larger than the steering force that can be generated by the first drive motor is required, there is no need to provide another drive motor, that is, Thus, a relatively large steering force can be generated without increasing the size of the vehicle steering system. On the other hand, when the absolute value of the deviation is larger than the predetermined value δ0, the process proceeds to step S23.

FIG. 7 is a diagram showing a second embodiment of the vehicle steering system according to the present invention. In this case, the same members as those used in the first embodiment are given the same numbers. In the present embodiment, the first steering shaft 41 includes the pinion shaft 2 a and the first electromagnetic clutch 5.
Two flexible shafts 41a interposed between
41b. These flexible shafts 41a,
Reference numeral 41b is a member corresponding to a portion made of a flexible material and capable of transmitting torque, and its detailed configuration is described in Japanese Patent Application No. 11-866666. Such flexible shafts 41a and 41b
Thus, the degree of freedom in mounting the vehicle steering system on the vehicle can be improved.

The first drive motor 42 and the encoder 42a included therein are arranged coaxially with the rack 2b. Further, the second electromagnetic clutch 43 disposed between the second steering shaft 6 and the third steering shaft 7,
When the second steering shaft 6 and the third steering shaft 7 are separated, a mechanical steering reaction force is generated.

FIG. 8 is a cross-sectional view showing a state in which a clutch that generates a mechanical steering reaction force when disconnected is connected.
Is a sectional view at the time of separation. The first already explained
The disc-shaped member 51 is rotatably arranged with a member 53 via a bearing 52, focusing on the difference from the second electromagnetic clutches 5 and 7. The member 55 that supports the electromagnet 54 has a shape that allows the member 55 to come into contact with the member 53 when separated, and a friction material 56 is disposed on the contact surface.

A member 57 projects in a direction perpendicular to the axis of the third steering shaft 8, and a coil spring 58 is connected between the end of the member 57 and the member 53. The operation at the time of connection is the same as that of the first and second electromagnetic clutches 5 and 7, except that the member 53 is connected to the member 55 via the friction material 56 at the time of disconnection. Thereby, the member 53 becomes the member 5
5, and is not fixed to the vehicle body or the like. On the other hand, the third steering shaft 8
Is rotatable, so that the coil spring 5
8 generates a steering reaction force. By adjusting the spring constant of the coil spring 58, a sense of discomfort during steering can be reduced.

The present invention is not limited to the above-described embodiment, and many modifications and variations are possible. For example, in addition to the steering wheel, a lever, a hand grip, a pedal, etc. can be used as the steering means.
A mechanism other than the rack and pinion type steering may be used as the steering mechanism.

Although the vehicle speed sensor is used as the traveling state detecting means, a lateral acceleration sensor, a longitudinal acceleration sensor, a yaw rate sensor, or a combination thereof may be used. As the first and second connecting and disconnecting means, other than the electromagnetic clutch can be used, and the first and second connecting and disconnecting means can be used.
A driving means other than a motor can be used. Further, a material other than a coil spring can be used as the elastic member, and a material such as that described in, for example, JP-A-10-259816 can be used as the flexible shaft.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a vehicle steering system according to the present invention.

FIG. 2 is a cross-sectional view of the clutch shown in FIG. 1 at the time of connection.

FIG. 3 is a cross-sectional view of the clutch shown in FIG. 1 when the clutch is disengaged.

FIG. 4 is a flowchart showing an operation of the first embodiment.

FIG. 5 is a diagram illustrating a relationship between a vehicle speed and a steering gear ratio in a state where one clutch is not mechanically connected and in a state where both clutches are mechanically connected.

FIG. 6 is a diagram showing operations of first and second drive motors.

FIG. 7 is a view showing a second embodiment of the vehicle steering system according to the present invention.

FIG. 8 is a cross-sectional view showing a state in which a clutch that generates a mechanical steering reaction force at the time of disconnection is engaged.

FIG. 9 is a cross-sectional view of a clutch that generates a mechanical steering reaction force when the clutch is disconnected.

[Explanation of symbols]

 1,41 First steering shaft 2 Rack and pinion type steering 2a Pinion shaft 2b Rack 3a, 3b Steering link 4a, 4b Wheel 5 First electromagnetic clutch 6 Second steering shaft 7,43 Second electromagnetic clutch 8 Third steering shaft 9 Steering wheel 10, 12 Gear 11, 42 First drive motor 11a, 13a, 42a Encoder 13 Second drive motor 14 Steering angle sensor 15 Vehicle speed sensor 16 Execution control unit (ECU) 20, 22 End 21a, 21b, 27, 28 , 29, 51 Disc-shaped members 23a, 23b, 52 Bearings 24, 54 Electromagnets 25, 53, 55, 57 Members 26 Projections 30 Bolts 31a, 31b, 31c, 31d, 56 Friction materials 32, 58 Coil springs 41a, 41b Flexible Shi Yaft V Vehicle speed θ1, θ2, θ3 Rotation angle

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) B62D 111: 00 B62D 111: 00 113: 00 113: 00 137: 00 137: 00 F-term (Reference) 3D030 DC01 DC25 DC29 DC39 3D032 CC03 CC34 CC48 DA03 DA04 DA23 DA25 DA29 DB03 DC33 DC34 DD01 EA01 EB04 EB05 EB12 EC22 EC31 EC40 GG01 3D033 CA03 CA12 CA13 CA14 CA17 CA18 CA21 CA23 CA31 CA32 CA33

Claims (12)

[Claims] A first shaft having one end connected to a steering mechanism; and a second shaft having one end connected to steering means for performing a steering operation by a driver.
A shaft, a third shaft disposed between the first shaft and the second shaft, a steering amount detecting unit for detecting a steering amount of the steering unit, and a running state detecting unit for detecting a running state of the vehicle. A control unit that issues a command based on the steering amount and / or traveling state; and a first unit that mechanically connects and disconnects the other end of the first shaft and one end of a third shaft in accordance with the command. Connecting and disconnecting means; second connecting and disconnecting means for performing mechanical connection and disconnection between the other end of the third shaft and the other end of the second shaft in accordance with the instruction; First driving means connected to the third shaft for generating a steering force according to the command; and a second driver mechanically connected to the third shaft for generating a steering reaction force or the steering force according to the command. Comprising the door, when the traveling-like is determined by said control means to be a normal traveling, the first connection and disconnection means,
The other end of the first shaft and one end of the third shaft are mechanically disconnected, and the second connection and disconnection means mechanically connects the other end of the third shaft and the other end of the second shaft. When the first driving means generates a steering force, and the control means determines that the first driving means is out of order, the first connection and disconnection means may be connected to the other of the first shaft. Mechanically connecting the end to one end of the third shaft, the second connection and disconnection means mechanically disconnects the other end of the third shaft and the other end of the second shaft, and A vehicle steering apparatus, wherein the means is configured to generate a steering force. 2. The method according to claim 1, wherein the first driving means generates a steering force such that a value obtained by dividing the steering amount by a steering gear ratio according to the traveling state becomes a wheel angle. The vehicle steering apparatus according to claim 1. 3. The first connecting / disconnecting means, when the control means determines that the traveling state is extremely low speed traveling and the steering amount is larger than a predetermined value. The other end of the third shaft is mechanically connected to one end of the third shaft, and the second connecting and disconnecting means mechanically disconnects the other end of the third shaft from the other end of the second shaft. 3. The vehicle steering apparatus according to claim 1, wherein both the first and second driving means are configured to generate a steering force. 4. A structure in which both the first and second driving means generate a steering force such that a value obtained by dividing the steering amount by a predetermined steering gear ratio becomes a wheel angle. The vehicle steering apparatus according to claim 3. 5. When the control means determines that both the first and second drive means have failed, the first connection / disconnection means connects the other end of the first shaft to a third shaft. And the second connection and disconnection means mechanically connects the other end of the third shaft and the other end of the second shaft, and the first drive means and The vehicle steering apparatus according to any one of claims 1 to 4, wherein the second driving unit is stopped. 6. The first connection and disconnection means mechanically disconnects the other end of the first shaft from the one end of a third shaft, and the second connection and disconnection means includes
If the target wheel angle is significantly different from the actual wheel angle when the other end of the third shaft and the other end of the second shaft are mechanically connected, the first drive means has failed. 6. The vehicle steering apparatus according to claim 1, wherein the control means is configured to be determined by the control means. 7. The first connection / disconnection means mechanically connects the other end of the first shaft and one end of a third shaft, and the second connection / disconnection means comprises:
If the target wheel angle is significantly different from the actual wheel angle when the other end of the third shaft and the other end of the second shaft are mechanically separated from each other, it is possible that the second drive means has failed. The vehicle steering apparatus according to claim 5, wherein the control means is configured to make a determination. 8. The vehicle steering system according to claim 6, wherein the target wheel speed is converted from the steering amount and a running state. 9. The method according to claim 8, wherein the second connection and disconnection means includes an elastic member that generates a steering reaction force when mechanically disconnecting the other end of the third shaft and the other end of the second shaft. The vehicle steering apparatus according to any one of claims 1 to 8, wherein: 10. When the first and second connection and disconnection means are supplied with an electric current, respectively, the other end of the first shaft, one end of the third shaft, and the other end of the third shaft are connected to each other. When the other end of the second shaft is mechanically connected to the other shaft and current is not supplied, the other end of the first shaft and one end of the third shaft, and the other end of the third shaft and the other The vehicle steering apparatus according to any one of claims 1 to 9, wherein the end is mechanically separated from the end. 11. The first driving means includes a gear mechanically connected to the first shaft, and a motor for transmitting a steering force to the first shaft via the gear, and
The drive means according to claim 1, further comprising a gear mechanically connected to the third shaft, and a motor for transmitting a steering reaction force or a steering force to the third shaft via the gear. The vehicle steering apparatus according to any one of the preceding claims. 12. The apparatus according to claim 1, wherein at least one of the first to third shafts has a portion made of a flexible material. Vehicle steering system.