JPH0989966A - Failure detecting circuit and its detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an open failure or short-circuit generated in a driving circuit in a full load current area by detecting the phase difference between a signal value for controlling the current value carried to a load and the voltage value generated in the driving circuit. SOLUTION: A duty signal (a) is converted into an integrated waveform signal (b) in an integrating circuit, and outputted from the terminal P1 of a CPU 4 to the terminal 2 of an IC 2. The IC 2 compares the magnitude of the signal (b) with the input signal of a terminal 3 as reference voltage and outputs a pulse signal (c). Terminals 4, 8 are subjected to noise removal by a capacitor 7, and a voltage is added thereto. The pulse signal (c) is outputted to the terminal 5 of the IC 1 as integrated waveform signal, compared in magnitude with the input signal of an output terminal 6, and outputted to a terminal 7. In a failure detecting circuit 1, by using that a driving waveform (c) has a phase delay in the control of actuator current by the duty signal (a), the voltage value of a fail-safe input signal (d) in each timing of leading edge and trailing edge of the duty signal (a) is detected, whereby a failure is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure detection circuit and a detection method thereof, and more particularly, to a failure detection circuit and a detection method thereof for detecting a failure of a drive control circuit such as an actuator.

[0002]

2. Description of the Related Art Conventionally, as a failure detection circuit for detecting a failure occurring in a drive circuit such as an actuator, a voltage generated in a load circuit is detected by a comparator, and an abnormal load current is detected based on the output from the comparator. What is detected is proposed (Japanese Patent Laid-Open No. 59-104565).
Reference).

[0003]

However, the conventional failure detection circuit as described above can detect a failure only at a specific load current. Further, since the voltage generated in the load circuit is input from the comparator, the circuit becomes expensive. The present invention has been proposed in order to solve the above-mentioned conventional problems, and an object thereof is to prevent an open failure or a short circuit occurring in a drive circuit such as an actuator or the like from occurring in a full load current range regardless of an inexpensive circuit configuration. It is an object of the present invention to provide a failure detection circuit and a detection method therefor that can be easily detected by.

[0004]

SUMMARY OF THE INVENTION To solve the above problems,
In order to achieve the object, the failure detection circuit according to the present invention has the following configuration. That is, in the failure detection circuit for controlling the current value flowing through the load to drive the load and detecting the failure that occurs in the drive circuit that drives the load based on the current value, Control signal output means for outputting a control signal to the load to control a current value to be applied to the load; voltage detection means for detecting a voltage value generated in the drive circuit by applying the load to the load; and the control signal. And means for detecting a failure occurring in the drive circuit based on the phase difference between the detection signal of the voltage value and the detection signal of the voltage value.

The failure detection method according to the present invention comprises the following steps. That is, in order to detect a failure that occurs in a drive circuit that drives the load based on the current value, a control circuit that controls the current value that is applied to the load by a predetermined control signal to drive and control the load. In the failure detection method, the voltage detection step of detecting a voltage value generated in the drive circuit by energizing the load, and the drive circuit from the phase difference between the predetermined control signal and the detection signal of the voltage value. And a step of detecting a failure that occurs.

As described above, in the failure detection circuit and the detection method thereof according to the present invention, the load is energized when the failure occurring in the drive circuit for driving the load is detected based on the value of the current supplied to the load. Operates to detect a failure occurring in the drive circuit from the phase difference between the control signal output from the control signal output means for controlling the current value and the detection signal of the voltage value generated in the drive circuit by energizing the load. To do.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a failure detection circuit according to an embodiment of the present invention. In FIG. 1, the failure detection circuit 1 includes an actuator S1, an actuator driving element Q1,
A resistor R11 for detecting a current flowing through the actuator drive element Q1, a current detection circuit 6, a duty generation circuit 3 for outputting a duty signal consisting of a predetermined pulse to the comparison circuit 5, and a duty signal output from the duty generation circuit 3. And a detection signal output from the current detection circuit 6 to determine a current output to the actuator drive element Q1, and a voltage detection circuit 2 to detect a drive voltage applied to the actuator S1. .

The actuator S1 is a battery such as + B
A linear solenoid connected to a power source, for example, A
It drives a valve that controls the line pressure of T (automatic transmission). Actuator drive element Q
Reference numeral 1 denotes a transistor, a linear solenoid S1 and a resistor R11 are connected in series to the collector, and an output voltage based on the current value determined by the comparison circuit 5 is applied to the base. When a voltage is applied to the base of the actuator drive element Q1 (transistor on state), the actuator S1 is energized as a solenoid.

The voltage detection circuit 2 and the duty generation circuit 3 are constructed as a part of the CPU 4 which controls the drive of the actuator S1. FIG. 2 is a circuit diagram showing a detailed configuration of the failure detection circuit shown in FIG. Further, FIG. 3 is a diagram showing signal waveforms at respective points in FIG. 1 to 3, the duty signal a of the duty generation circuit 3 (see FIG.
The waveform signal shown in (a) is a resistor R1 and a capacitor C.
The integrated circuit composed of 1 forms an integrated waveform signal b (waveform signal shown in FIG. 3B), which is output from the terminal P1 of the CPU 4 to the terminal 2 of the IC2. The IC2 corresponds to the comparison circuit 5 shown in FIG. The terminals 4 and 8 of the IC2 are power supply terminals, and noise or the like is removed by the capacitor C7 so that the voltage V
Is added. The output signal output from the output terminal 1 of the IC2 is applied to the base of the transistor Q2 via the resistor R12 to turn on the transistor Q2. When the transistor Q2 is turned on, the power supply voltage + B is applied between the collector and the emitter of the transistor Q2 via the resistor R13, so that the transistor Q1 is turned on. When the transistor Q1 is turned on, the resistor R14 and the diode D
A current flows through the circuit composed of the transistors Q1 and Q2 including 1 and, as described above, the actuator S1 receives the power supply voltage +
B is added and the solenoid is energized. Since the transistor Q1 is turned on / off based on the output signal from the above-mentioned IC2, the signal c applied to this solenoid becomes a pulse signal (waveform signal shown in FIG. 3C).

On the other hand, the pulse signal c becomes an integrated waveform signal in the integrating circuit composed of the resistor R10 and the capacitor C5,
It is output to the terminal 5 of the IC1. IC1 corresponds to the current detection circuit 6 shown in FIG. 1, and the integrated waveform signal is used as a reference voltage VRE.
As F, the magnitude of the input signal of the other terminal 6 is compared and output to the output terminal 7. The input signal to the other terminal 6 is input through the resistor R9 with noise removed by the capacitor C4. The charge accumulated in the capacitor C4 is the resistance R
7, R8 and the positively charged capacitor C6 cancel. The pulse signal output from the output terminal 7 is
I through the resistors R5 and R6 and the Zener diode ZD1
It is input to the terminal 3 of C2. The potential difference between the duty signal and the pulse signal input to the terminal 6 is the resistance R2, R3,
It is canceled by R4, the positively charged capacitor C2, and the capacitor C3.

On the other hand, the pulse signal c has noise removed by the resistor R0 and the capacitor C0 and is output to the IC3.
The IC 3 is an inverter element, which inverts the pulse signal c and outputs it as a fail-safe input signal d for failure detection to the voltage detection circuit 2 shown in FIG. 1 (waveform signal shown in FIG. 3D). Next, a failure detection method by the failure detection circuit of this embodiment will be described.

In the failure detection circuit shown in FIGS. 1 and 2, when the actuator current is controlled by the duty signal,
Using the fact that there is a phase delay in the actuator drive waveform c with respect to the duty signal a as shown in FIG. 3, the voltage value of the fail-safe input signal d at each of the rising and falling timings of the duty signal can be detected. Failure detection by (actuator drive element-load power supply disconnection,
Detection of short circuit, disconnection of actuator drive element, short circuit, etc.).

More specifically, referring to FIGS. 2 and 3, there is no short circuit between the actuator drive element (point c in FIG. 2) and the load power supply, and the actuator drive element (collector and emitter of the transistor Q1). In order to confirm that there is no disconnection failure, it is necessary to confirm that the fail-safe input signal d is 5V (point A shown in FIG. 3D) after the duty signal a changes from 5V to 0V. Just check.

Actuator drive element (c shown in FIG. 2)
(Point) -In order to confirm that there is no disconnection failure between the load power supply and that there is no short circuit failure in the actuator drive element (between the collector and emitter of the transistor Q1), the duty signal a changes from 0V to 5V. After that, the fail-safe input signal d becomes 0V (point B shown in FIG. 3D)
You can confirm that

As described above, in the failure detection circuit 1 of the present embodiment, a disconnection failure or a short-circuit failure which occurs in the actuator drive element due to the input voltage of the fail-safe input signal d at the rising and falling timings of the duty signal a. Since it can be detected easily and the fail-safe input signal d is input using the inverter IC3, an inexpensive circuit configuration can be obtained.

<Technical Effect of the Present Embodiment> In a conventional failure detection circuit, the CPU 4 for detecting a failure and the duty generation circuit 3 for generating a duty signal are generally constructed separately. In the conventional circuit configuration, the CPU
In the case of No. 4, since it is necessary to detect a failure by fetching both the duty signal output from the duty generation circuit 3 and the detection signal of the voltage value detected by the voltage detection circuit 2, the processing is complicated due to interrupt processing or the like. However, this is disadvantageous in that two input ports for the CPU 4 are required.

On the other hand, in the embodiment according to the present invention, CP
Duty signal output from U4 and voltage detection circuit 2
It is possible to obtain the detection signal of the voltage value detected by the other circuit without fetching it from another circuit, and the phase difference between the two signals
4 can be easily detected. In addition, when changing the frequency of the duty signal (generation of load current dither),
There is no need to change the time constants of the comparison circuit 5 and the current detection circuit 6, and the labor for circuit design can be saved.

The present invention can be applied to a modification or change of the above embodiment without departing from the spirit of the present invention.

[0019]

As described above, according to the present invention, when a failure occurring in a drive circuit for driving a load is detected based on the value of the current supplied to the load, the current value supplied to the load is determined. Since a failure occurring in the drive circuit is detected from the phase difference between the control signal output from the control signal output means for control and the detection signal of the voltage value generated in the drive circuit by energizing the load, an inexpensive circuit configuration Nevertheless, it is possible to easily detect an open failure or a short circuit that occurs in a drive circuit such as an actuator.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a failure detection circuit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a detailed configuration of a failure detection circuit shown in FIG.

FIG. 3 is a diagram showing signal waveforms at respective points in the circuit of FIG.

[Explanation of symbols]

 1 ... Failure detection circuit 2 ... Voltage detection circuit 3 ... Duty generation circuit 4 ... CPU 5 ... Comparison circuit 6 ... Current detection circuit

Claims (7)

[Claims] 1. A failure detection circuit for controlling a current flowing through a load to drive and control the load, and for detecting a failure occurring in a drive circuit for driving the load based on the current value. A control signal output unit that outputs a control signal to the load to control a current value for energizing the load; a voltage detecting unit that detects a voltage value generated in the drive circuit by energizing the load; A failure detection circuit, comprising means for detecting a failure occurring in the drive circuit based on a phase difference between the control signal and the detection signal of the voltage value. 2. A current detection means for detecting a current value to be applied based on a voltage value generated in the drive circuit, the control signal and a detection signal of the current value by the current detection means are compared, The fault detection circuit according to claim 1, further comprising: a comparison unit that controls a current value to be applied to the load based on the comparison result. 3. The failure detection circuit according to claim 1, wherein the voltage value generated in the drive circuit is input via an inverter element. 4. The failure detection circuit according to claim 1, wherein the comparison means is a comparator that uses a voltage value of a waveform signal formed from the control signal as a reference voltage. 5. The failure detection circuit according to claim 1, wherein the current detection unit is an operational amplifier that uses a voltage value generated by energization of the comparison unit as a reference voltage. 6. A control circuit for controlling a current value to be applied to a load by a predetermined control signal to drive and control the load,
In a failure detection method for detecting a failure that occurs in a drive circuit that drives the load based on the current value, a voltage detection step of detecting a voltage value that occurs in the drive circuit by energizing the load, And a step of detecting a failure occurring in the drive circuit based on a phase difference between the predetermined control signal and the detection signal of the voltage value. 7. A current detection step of detecting a current value to be applied based on a voltage value generated in the drive circuit, the predetermined control signal and a detection signal of the current value by the current detection means are compared. The fault detecting method according to claim 6, further comprising: a comparing step of controlling a current value applied to the load based on the comparison result.