JPH0592686U - Failure detection device - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to accurately determine a plurality of failures in a failure detection target device by hardware. A drive current target value of a motor for assisting steering of an electric power steering device set in advance by a fail condition determination circuit 1 and a detected value of a motor current are compared to determine whether the detected value is lower than the target value. Alternatively, the operating state of the motor is determined by detecting whether or not it is high, and a clock of a different frequency is oscillated from the oscillator 3 according to each operating state and input to the counter 4, while the target set in advance by the fail detection circuit 2 is set. Based on the value and the detected value to determine the presence or absence of fail,
When a failure occurs, a failure detection signal is output to the counter 4 to start counting, and when the counter 4 counts a predetermined number of clocks, an abnormality confirmation signal is output.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a failure detection device capable of detecting various failures in an electric power steering device or the like with hardware.

[0002]

[Prior Art]

 In an electric power steering system, when a failure is detected based on the comparison between the detected value of the drive current of the motor that outputs the steering assist force and the target value, a predetermined time constant is set in advance and the detected value is the target value. When the condition that is out of the range exceeds the time constant, it is determined that a failure has occurred and measures such as stopping the motor and releasing the clutch are taken.

[0003]

[Problems to be solved by the device]

 However, in the conventional device as described above, a counter electromotive force is generated in the motor for assisting steering during sudden steering, which makes it difficult for the motor drive current to flow, so the detected value is lower than the target value during rapid steering. However, in order to prevent this phenomenon from being mistaken for failure, it is necessary to set the time constant long, for example, about 0.5 sec.

On the other hand, if the detected value exceeds the target value and becomes excessive, it is necessary to immediately determine that a failure has occurred, for example, in about 0.03 seconds from the viewpoint of ensuring safety. Therefore, as described above. There is a problem that it is difficult to accurately detect faults with a configuration that sets only one type of time constant. The present invention has been made in view of such circumstances, and the purpose thereof is to change the abnormality determination time in hardware according to the type of failure so that a plurality of failures can be accurately detected. It is to provide a detection device.

[0005]

[Means for Solving the Problems]

 A failure detection device according to the present invention comprises a circuit for detecting an operating state of an abnormality detection target device, and a circuit for changing a time for establishing an abnormality of the abnormality detection target device according to an operation state detected by the detection circuit. Means for outputting an abnormality confirmation signal when the operation state detected by the detection circuit reaches the abnormality determination time set by the abnormality determination time changing circuit.

[0006]

[Action]

 According to the present invention, the abnormality confirmation time changing means can set the abnormality confirmation time according to the operation state of the abnormality detection target device, and each of the various abnormalities can be accurately detected.

[0007]

【Example】

 Hereinafter, the present invention will be specifically described with reference to the drawings showing an embodiment thereof. FIG. 1 is a block diagram of a failure detecting device according to the present invention, in which 1 is a fail condition judging circuit and 2 is a fail detecting circuit. The fail condition determination circuit 1 compares a target value that is preset and input, for example, when detecting a failure of the electric power steering device, with a target value of a drive current of a motor for steering assist and a detected value that is sequentially detected. If the detected value is lower than the target value, the fail condition B is determined, and if the detected value is higher than the target value, the fail condition A is determined, and the corresponding signals are output to the oscillator 3. The oscillator 3 is configured to output a clock having a different frequency to the counter 4 according to each signal input from the fail condition determination circuit 1.

On the other hand, the same target value and detection value are input to the fail detection circuit 2, and the input target value and detection value are compared, and the detection value is a predetermined value higher than the target value. When it is lower than the above value, or when the detected value is higher than the target value by a predetermined value or more, it is determined that the failure has occurred, and a signal is output to the counter 4 to start counting. The counter 4 starts counting the clock based on the detection signal from the fail detection circuit 2, and outputs an abnormality confirmation signal when counting a predetermined number n.

2 and 3 are waveform diagrams showing respective output signal waveforms of the clock oscillated from the oscillator 3, the fail condition judging circuit 1, the fail detecting circuit 2 and the counter 4, and FIG. 2 is a fail condition judging circuit. 1 shows the case where the fail condition B is judged, and FIG. 3 shows the case where the fail condition judgment circuit 1 judges the fail condition A as well.

When the fail condition judging circuit 1 judges that the fail condition is B and outputs the fail condition judging signal B as shown in FIG. 2 (c), the oscillator 3 is output from the oscillator 3 as shown in FIG. 2 (a). A clock having a cycle T ₁ is oscillated and input to the counter 4. When the fail detection circuit 2 detects a fail as shown in FIG. 2 (b), it outputs a fail detection signal to the counter 4, and the counter 4 starts counting. When the counter 4 counts n clocks, in other words, the counter 4 outputs an abnormality confirmation signal as shown in FIG. 2 (d) T ₁ × n time after the fail detection circuit 2 detects the occurrence of the failure. As a result, measures such as stopping the motor for steering assistance will be taken.

On the other hand, when the fail condition judging circuit 1 changes from the condition judged as the fail condition B as shown in FIG. 3 (c) to the fail condition A, the fail condition judging signal B is switched to A, As shown in 3 (a), the oscillator 3 oscillates by switching the frequency to the clock of the period T ₂ shorter than the period T ₁ . When the fail detection circuit 2 detects the occurrence of a failure as shown in FIG. 3 (b), the counter 4 starts counting clocks and counts the same number of clocks, that is, the fail detection circuit 2 fails. An abnormality confirmation signal is output from the counter as shown in FIG. 3 (d) after T ₂ × n hours from the occurrence detection, and similarly, measures such as stopping the motor for steering assist are taken. That is, in the fail condition A in which the detected value is higher than the target value, the abnormality determination time is shorter than in the fail condition B in which the detected value is lower than the target value.

In the above-described embodiment, the fail condition determination circuit 1 discriminates the operating state of the abnormality detection target device into two depending on whether the detected value is lower or higher than the target value, and selects two types from the oscillator 3. Although the case where the clock is output has been described, the present invention is not limited to this, and it goes without saying that two or more clocks may be output from the oscillator 3 in accordance with the respective operating states of the abnormality detection target device.

[0013]

[Effect of the device]

 As described above, in the device of the present invention, it is possible to set the abnormality confirmation time according to the operating state of the abnormality detection target device by the abnormality confirmation time changing circuit, and it is possible to accurately determine each type of abnormality. The present invention has excellent effects.

[Brief description of drawings]

FIG. 1 is a block diagram of a failure detection device according to the present invention.

FIG. 2 is a waveform diagram of each signal when the fail condition determination circuit determines that the fail condition is B.

FIG. 3 is a waveform diagram of each signal when the fail condition determination circuit determines the fail condition A.

[Explanation of symbols]

 1 Fail condition judgment circuit 2 Fail detection circuit 3 Oscillator 4 Counter

Claims (1)

[Scope of utility model registration request] 1. A circuit for detecting an operating state of an abnormality detection target device, a circuit for changing a time for determining an abnormality of the abnormality detection target device according to an operating state detected by the detection circuit, and the detection circuit. A failure detection device, comprising: means for outputting an abnormality confirmation signal when the detected operation state reaches the abnormality confirmation time set by the abnormality confirmation time changing circuit.