JPH0464406B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a device for detecting an abnormality in a steering angle detector used in an automobile.

<Prior Art> Conventionally, for example, a power steering device for an automobile is provided with a steering angle detector that detects a rotation angle of a steering shaft, and steering force is controlled in accordance with the steering angle. Therefore, if the steering angle detector malfunctions, it becomes impossible to control the steering force appropriately.

<Problems to be Solved by the Invention> Since the steering of a car is not always performed but is performed intermittently, the output of the steering angle detector also changes intermittently, and the output of the steering angle detector does not change. However, it cannot be determined that the steering angle detector is abnormal. For example, even if the steering angle detector outputs a constant value of zero due to a disconnection or short circuit, if the steering wheel is stopped at the neutral position, the zero value will be within the normal range. , it cannot be determined as abnormal. For this reason, it has not been possible to reliably detect an abnormality in the steering angle detector.

<Measures to solve the problem> Normally, when the car is stopped, the steering wheel may not be operated at all, but when the car is moving, the influence of the road surface shape may be affected even when driving straight. Small steering wheel operations are performed to compensate for changes in the running direction of the vehicle caused by the vehicle, and the steering wheel operations are constantly performed. The present invention has been made with attention to these points, and as shown in FIG. A running detection means D detects that the automobile is in a running state from a signal input by the speed input means C, and a steering angle is determined when the running detection means D determines that the automobile is in a running state. The present invention is characterized in that an abnormality determining means E is provided which outputs a signal that determines that the steering angle detector B is abnormal when the output of the detector B does not change.

<Function> When the running detecting means D determines that the vehicle is in a running state, the abnormality determining means E is activated in response to this and determines whether there is a change in the output of the steering angle detector B. Determine whether If there is no change, it is determined that the steering angle detector B is out of order.

<Examples> Examples of the present invention will be described below based on the drawings. FIG. 2 is a block diagram showing the configuration of a power steering device to which the present invention is applied. The rotational force of the steering wheel 50 is transmitted to the input shaft 54 via the steering shaft 52. 56 is a servo valve that controls the flow of pressure oil into the hydraulic cylinder 58 according to the rotational force of the input shaft 54. Reference numeral 58 operates a piston using pressure oil to rotate the steering arm shaft 62, and rotates the steering arm shaft 62.
This is a hydraulic cylinder that increases the steering force by swinging the steering arm 63 connected to the steering wheel 2. Pressure oil is sent to a pipe 65 by a pump 64 and returns to a tank 67 through a servo valve 56, a hydraulic cylinder 58, and a servo valve 56. The pump 64 is connected to an engine drive shaft (not shown) via a pulley 66. 60 is a solenoid for controlling a variable valve (not shown) provided in a conduit that communicates the high pressure chamber and the low pressure chamber of the hydraulic cylinder 58. The opening degree of the variable valve is controlled by the signal V1, the pressure in the high pressure chamber is adjusted, and the degree of amplification of the steering force is controlled.

The speed detector 10 consists of a vehicle speed sensor 11 and a speed counter 12 that counts its output pulses. The vehicle speed sensor 11 detects the rotation of a magnetic pole rotated by a speedometer cable as a pulse signal using a reed switch. The steering angle detector 20 includes a slit plate 21 disposed on the steering shaft 52, a photointerrupter 22 that detects light passing through the slit plate 21, and a waveform shaping circuit that shapes the waveform of the signal detected by the photointerrupter into a pulse waveform. 23, a direction determining circuit 24 that determines the rotational direction of the slit plate 21, and an addition/subtraction counter 2 that adds and subtracts the pulse output thereof according to the rotational direction.
It consists of 5. Since the slit plate 21 blocks light from the photointerrupter 22 at a frequency corresponding to its rotation speed, the Wheaton interrupter 22 outputs a number of pulses proportional to the amount of rotation of the steering shaft 52. Furthermore, since a pair of photointerrupters 22 are provided with a spatial phase difference of π/2, two-phase pulses A and B having a phase difference of π/2 are output from the photointerrupters 22, and the logic level of these two-phase pulses is The direction of rotation is determined by The control device 30 outputs V1 that controls the solenoid 60 to control the degree of amplification of the steering force, and also functions as a main part of an abnormality detection device that detects an abnormality in the steering angle detector 20. The control device 30 consists of a microcomputer 31, a memory 32, and input/output interfaces 33, 34. The speed input means, travel detection means, and abnormality determination means of the present invention are realized by software of a computer system.

FIG. 3 is a flowchart showing the processing of the microcomputer 31. This program is started by an interrupt at regular intervals from a real-time block generation circuit (not shown).

First, in the first step (100), the steering angle θ and vehicle speed V data output from the speed detector 10 and the steering angle detector 20 are read, and then,
In step (101), it is determined whether the vehicle speed V is within the delimiter speeds S ₁ to Sn.

As shown in Figure 4, the vehicle speed divisions are as follows:
A large number of speeds are set at regular intervals, and at step (100), the vehicle speed V is set as the speed _S1 to S1.
Determine whether it is either Sn.

When it is determined that the vehicle speed V has reached one of the delimiter speeds S ₁ to Sn, the delimiter speed passed previously is determined.
It is determined in step (102) whether or not it is the same as OV. In this step (102), the fact that it is determined to be the same as the dividing speed OV passed before means that there is no change in the vehicle speed, that is, the vehicle is stopped, and in this case, there is no change in the vehicle speed. Returns to the main routine without performing any processing.

On the other hand, if the vehicle speed V read this time is different from the dividing speed OV passed previously, it is determined that the vehicle speed has changed, that is, the vehicle is running, and the abnormality determination process from step (103) is performed. .

That is, in step (103), it is determined whether there is a difference greater than or equal to the set value ε between the previously stored steering angle Oθ and the currently read steering angle θ.
If there is no difference, it is determined that the steering angle detector 20 is out of order, and the process proceeds to step (105), where an abnormality flag ERFLG is set. Also, the steering angle
If there is a difference greater than the set value ε between Oθ and the steering angle θ, it is determined that the steering angle detector 20 is operating correctly, and the process moves to step (104) to reset the abnormality flag ERFLG. do.

After this, move to step (106),
The steering angle θ is stored as Oθ, the vehicle speed V is stored as the previously passed dividing speed OV, and the process returns to the main routine.

In this way, since the abnormality of the steering angle detector 20 is determined based on the fact that the output of the steering angle detector 20 does not change when the vehicle is in a running state, the output of the steering angle detector 20 while the vehicle is stopped is determined. Abnormalities in the steering angle detector 20 can be stably detected without detecting the fact that the steering angle detector 20 does not change as an abnormality. Also,
When driving, minute steering wheel operations are performed to correct changes in the running direction of the vehicle due to the influence of the road surface shape even when driving straight ahead, and since steering wheel operations are constantly being performed, the output of the steering angle detector 20 By not changing, a failure of the steering angle detector 20 can be reliably detected.

Note that it may be determined that the vehicle is in a running state when the vehicle speed V exceeds the set value, but in this case, if the speed detector 10 malfunctions, the vehicle speed exceeding the set value will be detected by the speed detector 10. If the signal is output all the time, it will be determined that the vehicle is running even when it is stopped, making it impossible to make a normal abnormality determination. Therefore, a more reliable abnormality determination can be made by determining whether or not the vehicle is running based on a change in the vehicle speed V as in the above embodiment.

Furthermore, as a process when an abnormality is determined, the number of times an abnormality occurs may be counted, and the abnormality processing may be performed only when the value exceeds a certain value.This prevents erroneous determination of an abnormality. be able to.

<Effects of the Invention> As described above, in the present invention, the output of the steering angle detector is adjusted not only under the condition that the vehicle speed signal is above a certain level but also under the condition that the output of the vehicle speed detector is actually changing. Since the steering angle detector is detected as abnormal when the speed sensor does not change, even if the speed detector is malfunctioning and a signal is constantly being output, the steering angle detector will not be mistakenly detected as abnormal. This has the advantage that failure of the steering angle detector can be reliably detected.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram for clearly demonstrating the present invention.
2 to 4 show embodiments of the present invention,
Fig. 2 is a block diagram showing the configuration of the device of this embodiment, Fig. 3 is a flowchart showing the processing of the microcomputer used in the device, and Fig. 4 is a time chart showing changes in the speed of the car. . 10... Speed detector, 20... Steering angle detector,
30...control device, 21...slit plate, 22...
...Photo interrupter, 50...Steering wheel, 52...Steering shaft, 56...
Servo valve, 60... solenoid, 62... steering arm shaft, 63... steering arm, 64... pump, 67... tank.

Claims (1)

[Claims] 1. A device for detecting an abnormality in a steering angle detector of a vehicle, comprising speed input means for inputting a signal from the speed detector for detecting the traveling speed of the vehicle;
It is determined which of a plurality of speed divisions the signal input by the speed input means is, and if the signal inputted this time by the speed input means is different from the speed division input last time. a determining means for determining that the vehicle is in a running state, and a determination that the steering angle detector is abnormal because the output of the steering angle detector does not change when the determining means determines that the vehicle is in a running state; An abnormality detection device for a steering angle detector, comprising: abnormality determination means for outputting a determination signal.