JPS62112070A - Detecting device for wire breaking of sensor - Google Patents

Abstract

PURPOSE:To securely and easily detect the wire breaking of a sensor by providing an electronic circuit which becomes active when the sensor generates no output and monitoring the output of this electronic circuit. CONSTITUTION:The base circuit of a transistor (TR) 16 is connected to the output side of the sensor 14 through a comparing circuit 15. The output of this TR 16 is supplied to the comparing circuit 23 of a control circuit 17. If the coil 13 of the sensor 14 is broken, the TR 6 turns off and its output goes up to the high level, so the output 32 of the control circuit 17 also rise to the high level, so that the breaking of the sensor coil 13 is detected. Further, even if a lines l11, l12, or l13 is broken, the input 22 to the comparing circuit becomes high, so the output 32 of the control circuit 17 goes up to the high level, the disconnection state is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sensor disconnection detection device that detects whether a sensor is disconnected when there is no output from the sensor.

Background technology A good example of the prior art is shown in FIG.

In order to detect the wheel speed of an automobile, a rotary plate 1 made of a ferromagnetic material and having a notch formed in the circumferential direction is installed on the wheel.
In the circuit 9, a sensor 4 including a permanent magnet 52 and a coil 3 wound around the permanent magnet 2 is provided in relation to the rotating plate 1. The output from sensor 4 is sent to comparison circuit 5! Can be tested. The comparison circuit 5 includes a resistor R
1. Level discrimination is performed at the voltage level set by R2, the waveform is shaped, and the transistor 6 is set to 0N10FF.
let The output from transistor 6 is from resistor R3 to line J! 1 and is applied to the detection circuit 8 of the control circuit 7. This line, el (by Tsuchiyama II), is also connected to the circuit 7 by lines 2 and 31, which are pulled up by resistor R4.

When the vehicle is stationary and therefore there is no output from sensor t, the output of comparator circuit 5 is at a low level and transistor 6 is therefore cut off.

Problems to be Solved by the Invention In such prior art, when there is no output from the sensor 4, it is assumed that the sensor 4 is disconnected or the line is disconnected.
1 +72, J! It is not possible on the control circuit 7 side to identify that 3 is disconnected.

When a car is driven with a wire breakage occurring, the control circuit 7 detects that the waveform from the circuit 9 is not generated, and only then does it become clear that the wire is broken. The presence or absence of such disconnection is determined by the running speed of the car.
From the perspective of safe driving, it is desirable that the vehicle be detected at:

An object of the present invention is to provide a sensor disconnection detection device that can detect whether a disconnection has occurred when there is no output from the sensor.

Means for solving disconnection points The present invention is characterized in that it includes a sensor, an electronic circuit that becomes active when there is no output from the sensor, and means for detecting an active state of the electronic circuit. It is a detection device.

Function According to the present invention, the electronic circuit is in an active state when there is no sensor output, and if a disconnection occurs, the electronic circuit is not in an active state.

Therefore, by detecting whether the electronic circuit is in an active state, it is possible to detect whether a disconnection has occurred.

Example Figure fjS1 is an electrical circuit diagram of an embodiment of the present invention.

In order to detect the wheel speed of the vehicle, rotating plates 11 made of ferromagnetic material are attached to the 11 wheels.

In one circuit, a permanent magnet 12;
A sensor 14 including a coil 13 wound around the sensor 14 generates an electromotive force when the rotary plate 11 rotates.

The output from this sensor 14 is applied to an inverting input terminal of a comparison circuit 15. The discrimination level set by the resistors R11 and R12 is applied to the non-inverting input terminal of the comparison circuit 15. The output from the comparison circuit 6 is applied to the base of the trannostar 16. trannosta 16
The output of is led out to line 11 via resistor R13. The circuit 19 includes the aforementioned sensor 14 and the remaining electric circuits integrally housed therein, and includes not only the line Jg11 but also the line Jg12. 13 to the control circuit 17. A resistor R15 is connected between a line 20 connected to the liner 13 and a line 21 connected to the inverting input terminal of the comparison circuit 15.

In the control circuit 17, the line 22 connected to the line 11 is pulled up by a pull-up resistor R]4. The line 22 is input to the non-inverting input terminal of the comparator circuit 23. The inverting input terminal of the comparator circuit 23 is
A divided voltage for setting the discrimination level is applied by resistors R16 and R17.

Comparison circuit 23 includes a final stage trannostar 24 and a resistor 25. When the voltage applied to the non-inverting input terminal of the comparison circuit 23 is equal to or higher than the discrimination level applied to the inverting input terminal, the trannostar 24 is cut off and a high level signal is applied to the output line 26. When the voltage at the non-inverting input terminal is below the discrimination level, tranostor 24 is conductive and line 26 is low and al.

A capacitor C1 is connected to the line 26 via a charging resistor R22. A resistor R2B is connected in parallel to the capacitor C1. A series circuit consisting of a discharging resistor R18 and a diode D1 is connected in parallel to the charging resistor R22. The output of capacitor C1 is applied from line 27 to the non-inverting input terminal of comparator circuit 23. Comparison circuit 28
The discrimination level of is set by resistors R19 and R20.

While the automobile is running, the rotating plate 11 rotates, and as a result, an electromotive force having a waveform shown in FIG. 2 is obtained from the sensor 14 to the line 21. The comparator circuit 15 shapes the waveform of the output from the sensor 14, and the shaped rectangular wave output is given to the control circuit 17 from the line node 11.

In the control circuit 17, the line node 1 is
1 and receives the signal via line 26 as shown in FIG. 3 (1).
At times 1 to t4, waveforms are derived. The frequency of the pulses in this line 26 corresponds to the wheel speed. At time points 1 to E1a, comparison circuit 2
The No. 3 trannostar 24 is cut off, the line 26 is at a high level, and at this time the capacitor CI is charged via the charging resistor R22. At time Lla-t2, transistor 24 is conductive and line 26 is at a low level. At this time, capacitor c1 is rapidly discharged via resistor R18 and diode D1. Here, R22>R18 (1) is established. This makes it possible to detect the wheel speed with high accuracy up to a high speed range. capacitor ci
The output is subjected to level discrimination and waveform shaping by the comparator circuit 28. The output waveform of the capacitor c1 on the line 27 is as shown in FIG.
is lower than the discrimination level 31 set by 20. Therefore, the third
The output indicated by CU(3) remains at a low level.

When it is detected in the control circuit 17 that the rectangular wave derived from the comparison circuit 23 to the line 26 is at the same level over 50+n5ec or more, the automatic Il
l is stopped or the sensor is broken and 1! can be cut off. In this state, when there is no disconnection in the census 4, etc., the line 21 connected to circuit 9 is kept at a low level, so the output of the comparison circuit 15 is at a high level, and the transistor 16 is turned on. There is. Therefore, line 22 in control circuit 17
is set to a low level, and the transistor 24 of the comparison circuit 23 is conductive. Line 26 is therefore at a low level. This state is shown at time L in Fig. 3 (1).
5 As shown in Section 1 below.

The comparison circuit 28 derives a low level signal to the line 32 during normal operation when no disconnection occurs.

If a disconnection occurs in the coil 13 or line 11 of the sensor 14, the transistor 1 will be disconnected when the fill 13 is disconnected.
6 is cut off and line 22 is connected to l! of resistor R14. II! I
It is considered to be at a high level. Comparison circuit 23
1 runno star 24 is shut off and line 26 is set to 5.
Thereafter, the resistor 25 functions to set the signal to a high level. Therefore, the capacitor C1 is charged by the action of the resistor R22.

At time L6, the voltage on line 27 increases across resistor R1.
, 9, and R20, the comparator circuit 28 outputs a high-level signal to the line 32 as shown in Figure (3) in @3 of the comment. By keeping the line 32 at a high level in this way, it can be seen that a disconnection has occurred.

Lysono 12. When the circuit 13 is disconnected, the transistor 16 is cut off. Therefore, the line 22 in the control circuit 17 becomes high level due to the action of the resistor R14, and a high level signal is derived from the 2-in 32 as described above.

As mentioned above, when the car is stopped and there is no disconnection in the sensor 14, the line 21 is at a low level, so the comparator circuit 15 applies a high level signal to the base of the transistor G. This causes transistor 16 to become active at W +iTI L. Further, when the sensor 14 is disconnected, the transistor 16 is cut off as described above. Therefore, the control circuit 17 detects whether the transistor 16 is in the active state, and if the transistor 16 is not in the active state, the sensor 1
It can be identified that there is a break in wires such as 4. In the example No. 1117J, the sensor or line disconnection, that is, the fact that line 26 has been at a high level for a certain period of time, is identified by the electric circuit after line 26, but the level of line 26 is directly detected by the microcomputer. Of course, it is possible to enter and identify the

FIG. 4 is an electrical circuit diagram of another embodiment of the present invention. The circuit 33 includes a sensor 34, and the output from the sensor 34 is given to a disconnection detection circuit 35 and a waveform shaping circuit 36. . The disconnection IQ, +2 output circuit 35 derives a high level signal to the line 37 when a disconnection occurs.

The waveform shaping circuit 36 shapes the waveform of the pulse from the sensor 24 and outputs it to a line 38 . The three logic circuits invert the output from lines 37 and 38 by an inverter circuit 40 and 41, and the output from the inverter circuit 40 and 41 is ANDed.
Given on date 42. The output from the AND date 42 is applied to an output circuit 43 and then to a control circuit 44 via a line 11. The control circuit 44 is also connected to the line node 12.
．． , gl 3 to the circuit 33. The control circuit 44 has a configuration similar to that of the control circuit 17 described above.

Such a circuit 33 achieves the operations shown in Table 1.

When the sensor 34 is not disconnected, the disconnection detection circuit 3
5 derives a low level signal to line 37 as described above. The car is stationary and therefore the sensor 34
When the signal is not output and is therefore at a low level, the waveform shaping circuit 36 outputs a low level signal on line 38. Thus, the AND date 42 of the logic circuit 39 derives a high level signal, and the output circuit 43 outputs a line! A high level signal is derived from 11. In this way, the sensor 34 receives i! When not performing l1ItA, it remains active.

When the sensor 34 does not have a wire breakage and therefore the output on the line 37 from the wire breakage detection circuit 35 is at a low level, the sensor 34 performs a detection Q + and sends a high level pulse to the line 38 from the waveform shaping circuit 3G. When such a signal is derived, the l\ND date 42, and therefore the output circuit 43, derives a low level signal to the line 11. When the output from the sensor 34 is a pulse, the pulse is output to the line 11.

When the sensor 34 is disconnected, the disconnection detection circuit 35
7, derive a high-level signal, and then A N D
The output of date 42 remains at a low level. As a result, the output circuit 43 continues to output a low level signal to line No. 1. In Table 1, the X mark indicates sensor 34.
The output of the three A N D dates 42 of the logic circuits is determined regardless of whether the output of is at a high level or a low level.

In the embodiments shown in Figures 1 to 3 above, ':'PJ1, when there is no output from the sensors [, 3,
In the illustrated embodiment, the output circuit 43 is configured to derive a high level signal such that such an active state is achieved, and such an active state is This is a state that is first achieved when the sensors 14, 34, etc. are not disconnected when the power is applied.

Effects As described above, according to the present invention, since the electronic circuit becomes active when there is no output from the sensor, it is possible to determine with certainty whether the sensor is disconnected by detecting the active state. It becomes possible.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of an embodiment of the present invention, FIG. 2 is a diagram showing the output waveform from the sensor 14, and FIG. 3 is a control circuit]
FIG. 4 is a waveform diagram for explaining the motion of the ear according to another embodiment of the present invention. 'l! Figure 5 is a prior art electrical circuit diagram. 11... Rotating plate, 13... Coil, 14,3. ↓・
...Sensor, 15.23.28...Comparison circuit, 16.
24... Trannostar, 17.4i... Control circuit,
35...1 new line detection circuit, 36...waveform shaping circuit,
39...Logic circuit, 43...Output circuit, C1...
Capacitor, R1-R20, R22, R23, R25・
...Resistance, Dl...Guiode

Claims (1)

[Scope of Claim] A sensor disconnection detection device comprising: a sensor; an electronic circuit that becomes active when there is no output from the sensor; and means for detecting an active state of the electronic circuit.