JPH06115449A - Electric motor type power steering device - Google Patents

Abstract

PURPOSE:To reduce the deterioration of the turning controllability by reducing the steering force necessary when an abnormal condition is generated in an electric motor type power steering device so as to reduce the steering burden of a driver. CONSTITUTION:This electric motor type power steering device is provided with a motor M1 to drive a steering linkage member S through a clutch C, a steering condition detecting device M2, and a control device M3 to control the motor according to the detected steering condition. When an abnormal condition in the power steering device is detected by an abnormality detecting device M4, and an abnormality detecting signal is output, the motor control by the control device is stopped by an assist control stopping device M5, so as to release the clutch C, and at the same time, the air pressure of a tire is increased by a tire air pressure control device M6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering device for vehicles such as automobiles, and more particularly to an electric power steering device.

[0002]

2. Description of the Related Art An electric power steering apparatus for a vehicle such as an automobile has heretofore generally been a motor for driving a steering linkage member such as a rack bar via a clutch and a steering gear box, and a controller for controlling the rotation of the motor. The control device is configured to generate a required steering assist force by controlling the motor based on the detection results of various sensors.

As one of such electric power steering devices, for example, as disclosed in Japanese Patent Laid-Open No. 60-209365, when an abnormality occurs in the power steering device, the control of the motor is stopped and the clutch is released to turn the power on. 2. Description of the Related Art An electric power steering device configured to stop assist control has been conventionally known.

According to the electric power steering apparatus as described above, when an abnormality occurs in the power steering apparatus, the rotation control of the motor is stopped and the clutch is released to improperly control the motor, resulting in an inappropriate power assist. Is surely prevented.

[0005]

However, in the conventional electric power steering system as described above, when an abnormality occurs in the power steering system, the steering assist force is not generated at all, so that the required steering force becomes high. As a result, there is a problem that the steering burden on the driver increases and the turning maneuverability of the vehicle deteriorates.

In view of the above-mentioned problems in the conventional electric power steering apparatus, the present invention requires a lower steering force than the conventional case when an abnormality occurs in the power steering apparatus. It is an object of the present invention to provide an improved electric power steering device capable of reducing the steering load of the vehicle and reducing the deterioration of the turning controllability of the vehicle.

[0007]

According to the present invention, the above-described object is achieved by a motor M for driving a steering linkage member S via a clutch C as shown in FIG.
1 and steering state detection means M2 for detecting the steering state of the vehicle
And an abnormality detecting means M4 for detecting an abnormality in the power steering apparatus and outputting an abnormality detection signal by using an electric power steering apparatus having a control means M3 for controlling the motor according to the detected steering state. , An assist control stopping means M for stopping the control of the motor by the control means and releasing the clutch based on the abnormality detection signal.
5 and tire pressure control means M6 for increasing the tire pressure based on the abnormality detection signal.

[0008]

According to the above-mentioned structure, when an abnormality occurs in the power steering device, the assist control stopping means M5 stops the control of the motor M1 to release the clutch C to stop the power assist control and the tire pressure. Since the tire pressure is increased by the control means M6 to reduce the frictional resistance between the tire and the road surface when the tire is steered and steered, an abnormality occurs in the power steering device and power assist is performed. If the steering wheel is not lost, the steering force required becomes lower than in the conventional case, whereby the driver's steering load is reduced and the turning maneuverability of the vehicle is reduced.

[0009]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic structural view showing one embodiment of the electric power steering apparatus according to the present invention, and FIG. 3 is shown in FIG.
3 is a block diagram showing an electronic control device shown in FIG.

In FIG. 2, reference numeral 10 denotes a steering wheel. The steering wheel 10 is a rack bar 1 as a steering linkage member via a steering shaft 12 and a steering gear box 14.
6 is driven. A power unit 20 is drivingly connected to the steering shaft 12 by a gear reduction mechanism 18. The power unit 20 is a motor 22
And an electromagnetic clutch 24 for selectively drivingly connecting the gear reduction mechanism 18 and the motor 22.

In the illustrated embodiment, the steering shaft 12 is provided with a steering angle sensor 26 for detecting the steering angle θ and a torque sensor 28 for detecting the steering torque T, respectively. Electronic control unit 3
2 is supplied. In addition, the electronic control unit 3
A signal indicating the vehicle speed V detected by the vehicle speed sensor 34 and a signal indicating the rotation angle φ of the motor 22 detected by the rotation angle sensor 36 are also input to the vehicle 2.

As shown in detail in FIG. 3, the electronic controller 32 includes a microcomputer 38, which is a central processing unit (CPU) 40.
, Read only memory (ROM) 42, random access memory (RAM) 44, and input port device 46
And an output port device 48, which are connected to each other by a bidirectional common bus 50.

As will be described later, the electronic control unit 32 outputs a control signal to the electromagnetic clutch 24 via the drive circuit 54 at the start of operation to drive and connect the gear reduction mechanism 18 and the motor 22 and is detected by the torque sensor. Steering torque T
The steering assist amount is calculated based on the above, and a voltage signal corresponding to the assist amount is output to the motor 22 via the drive circuit 52. Further, the electronic control unit 32 outputs a control signal to the air pressure control unit 56 and the alarm lamp 58 when an abnormality of each sensor or an abnormality such as a motor lock occurs, whereby the tire air pressure not shown in the figure is obtained. It is designed to boost the voltage and turn on the alarm lamp.

The pneumatic control unit 56 is an electronic control unit 32.
The tire may have any structure as long as it can increase the air pressure of the tire based on the control signal from, for example, Japanese Utility Model Laid-Open No. 57-97707 and Japanese Patent Laid-Open No. 109109/1989.
It may have a structure as described in the publication.

The operation of the illustrated embodiment will now be described with reference to the flow chart shown in FIG.

First, in step 10, the control signal is output to the electromagnetic clutch 24 via the drive circuit 54 to connect the clutch, and in step 20, the detected value detected by the steering angle sensor 26 or the like is detected. The signal indicating is read. In step 30, the steering assist amount is calculated based on the steering torque T detected by the torque sensor 28, the vehicle speed V detected by the vehicle speed sensor 34, and the like.
In step 40, a control signal of a voltage corresponding to the assist amount calculated in step 30 is output to the motor 22 via the drive circuit 52, whereby a required steering assist force is generated.

The calculation of the assist amount in step 30 is well known in the art and does not form the subject of the present invention. Therefore, a detailed description of the procedure of calculating the assist amount will be given. Although omitted, the assist amount may be calculated in any manner as long as it is calculated according to at least the steering torque.

In step 50, it is determined whether or not an abnormality has occurred in the power steering device, and if it is determined that no abnormality has occurred, then step 6
At 0, it is determined whether or not the number N of occurrences of abnormality detection is 0, and when it is determined that N = 0, the process directly returns to step 20 and it is determined that N = 0 is not established. When is performed, the number of times N is reset to 0 in step 70, and then the process returns to step 20. When it is determined in step 50 that an abnormality has occurred, the number N is incremented by 1 in step 80, and it is determined whether the number N is 3 in step 90. N
If it is determined that it is not = 3, step 20
Returning to, when it is determined that N = 3, the process proceeds to step 100.

It should be noted that the determination as to whether or not an abnormality has occurred in the power steering device may be performed in any manner. For example, the abnormality detection of the torque sensor 28 may be determined by the applicant of the present application. It may be carried out by the method described in the specification and drawings of Japanese Patent Application No. 4- (serial number AT-4874), and the abnormality detection of the motor 22 or the rotation angle sensor 36 is performed by the control signal to the motor and the output of the rotation angle sensor. May be performed according to the correspondence relationship of.

In step 100, the energization of the motor 22 is stopped and the output of the control signal to the electromagnetic clutch 24 is stopped, so that the clutch is released. In step 110, the air pressure control device 56 is operated to increase the air pressure of each tire by a predetermined amount or to a predetermined value, and in step 120, a control signal is output to the alarm lamp 58. The alarm lamp is turned on.

Thus, according to the illustrated embodiment, when each part of the power steering device is operating normally,
When the determination of No is made in Step 50, Steps 20 to 40 are repeatedly executed, whereby a required steering torque is applied from the power unit 20 to the steering shaft 12 to perform power assist.

If an abnormality occurs in the power steering device, a yes determination is made in step 50,
If the abnormality is detected three times in succession, a yes determination is made in step 90, the power assist control is stopped in step 100, and the air pressure of each tire is increased in step 110. As a result, the frictional resistance between the tire and the road surface at the time of turning etc. is reduced, and thereby the turning maneuverability of the vehicle due to the lack of power assist is reduced, and an alarm is issued at step 120. When the lamp 58 is turned on, the driver of the vehicle is alerted that an abnormality has occurred in the power steering device.

Further, according to the illustrated embodiment, steps 100 to 120 are not executed unless the abnormality is detected three times in succession, so that the abnormality of the power steering device is erroneously detected and the abnormality is detected based on the detection. Although there is no abnormality in the power steering device, step 10
0 to 120 is executed, that is, the alarm lamp 5
It is surely prevented that 8 is turned on, the tire air pressure is increased more than necessary, and the power steering device is switched to the manual steering device.

Although the present invention has been described in detail above with reference to specific embodiments, the present invention is not limited to such embodiments, and other various embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art that it is possible.

[0026]

As is apparent from the above description, according to the present invention, when an abnormality occurs in the power steering device, the assist control stopping means M5 stops the motor control and the clutch is released to perform the power assist control. At the same time as the suspension, the tire air pressure control means M6 increases the tire air pressure to reduce the frictional resistance between the tire and the road surface when the tire is steered and steered. The steering force required when the power assist is not performed is reduced as compared with the conventional case, whereby the driver's steering load can be reduced and the turning maneuverability of the vehicle can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an electric power steering device according to the present invention in correspondence with the description of the claims.

FIG. 2 is a schematic configuration diagram showing one embodiment of an electric power steering device according to the present invention.

FIG. 3 is a block diagram showing the electronic control device shown in FIG. 2.

4 is a flowchart showing a control flow achieved by the electronic control device shown in FIGS. 2 and 3. FIG.

[Explanation of symbols]

 10 ... Steering wheel 12 ... Steering shaft 14 ... Steering gear box 16 ... Rack bar 22 ... Motor 24 ... Electromagnetic clutch 26 ... Steering angle sensor 28 ... Torque sensor 32 ... Electronic control unit 34 ... Vehicle speed sensor 36 ... Rotation angle sensor 56 ... Pneumatic pressure Controller 58 ... Alarm lamp

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B62D 119: 00 137: 00

Claims (1)

[Claims] 1. An electric motor having a motor for driving a steering linkage member via a clutch, a steering state detecting means for detecting a steering state of a vehicle, and a control means for controlling the motor according to the detected steering state. Type power steering apparatus, an abnormality detecting means for detecting an abnormality in the power steering apparatus and outputting an abnormality detection signal, and based on the abnormality detecting signal, the control means stops the control of the motor and releases the clutch. An electric power steering apparatus comprising: an assist control stopping means and a tire air pressure control means for increasing the tire air pressure based on the abnormality detection signal.