JPH011974A - Self-diagnosis circuit of indicating device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a self-diagnosis circuit used in an indicating device such as a speedometer for a vehicle.

B6 Background of the Invention For example, Japanese Patent Application No. 61-82433 discloses a self-diagnosis circuit for a crossed coil type indicating device used in a speedometer system for a vehicle. This self-diagnosis circuit outputs a pseudo vehicle speed signal corresponding to a certain vehicle speed to cause the speedometer to swing, thereby diagnosing a speedometer failure. In other words, a malfunction in the speedometer system is thought to be a malfunction in the speedometer itself or a malfunction in the vehicle speed sensor that outputs vehicle speed pulses, but if the speedometer does not fluctuate during normal driving or during self-diagnosis, it is likely that the speedometer is malfunctioning. If the sensor shakes during diagnosis, it can be diagnosed as a faulty vehicle speed sensor.

Incidentally, a signal proportional to the vehicle speed obtained by this type of vehicle speedometer system is supplied as an external output signal to other systems such as an engine electronic control system. Further, in this type of speedometer system, a 10kn+/h signal indicating that the vehicle speed is 10km/h or less is generated and is supplied to other systems as an external output signal in the same way as the above-mentioned signal.

Problems to be Solved by the C0 Invention However, although the above-mentioned self-diagnosis circuit is capable of diagnosing failures of the speedometer and vehicle speed sensor, it cannot determine abnormalities in the above-mentioned external output signals.

For this reason, for example, if the engine electronic control system does not operate normally, it may be due to an abnormality in the supplied external output signal itself.
It takes a lot of effort to determine whether the engine electronic control system itself is abnormal, and improvements in workability are desired.

SUMMARY OF THE INVENTION An object of the present invention is to provide a self-diagnosis circuit for an indicating device that can diagnose failures in the indicating device itself as well as abnormalities in external output signals supplied to systems other than the indicating device.

Means for solving the D0 problem will be explained with reference to FIG. a sensor means 11 that outputs a sensor signal according to a physical quantity; a pseudo signal output means 25 that outputs a pseudo signal equivalent to the sensor signal and having at least first and second patterns in the self-diagnosis mode; a detection means 14 that outputs a detection signal corresponding to the magnitude of the physical quantity based on the pseudo signal; an instruction means 16, 17° SM that uses the detection signal to indicate a value corresponding to the physical quantity; Based on the physical quantity, a signal forming means 18 (20) forms an external output signal to be outputted to the outside for controlling according to the physical quantity, and the external output signal and the detection signal are inputted and the external output signal is normally output. gate means 22 that allows the detection signal to pass only when the detection signal is directly input from the detection means 14 and the gate means 22
When the first pattern of the pseudo signal is output in the self-diagnosis mode, the detection signal from the gate means 22 is selected, and the second pattern of the pseudo signal is selected. A signal switching means 15 selects the detection signal from the detection means 14 and inputs it to the instruction means when the pattern is being outputted, and selects the detection signal from the detection means 14 and inputs it to the instruction means in the normal mode. Be equipped.

In the E1 action normal mode, when the detection means 14 outputs a detection signal based on the sensor signal, the detection signal is sent to the instruction means 16, 17 . The physical quantity indicated by the sensor signal is indicated by the physical quantity supplied to the SM. In the self-diagnosis mode, the detection means 14 supplies a detection signal to the gate means 22 and the signal switching means 15 using a pseudo signal. On the other hand, the signal forming means 18 (20) outputs an external output signal to the gate means 22 based on the first pattern of the pseudo signal. If the external output signal is normal, the gate means 22 outputs a detection signal. Here, when the first pattern of pseudo signals is being output, the switching means 15 selects the input on the gate means 22 side, so that the detection signal from the gate means 22 passes through the switching means 15 to the instruction means 16. 17. It is supplied to the SM and specifies a predetermined physical quantity. If the external output signal is abnormal, gate means 2
Since the detection signal is not outputted from the external output signal 2, the instruction means SM does not instruct the predetermined value, thereby making it possible to diagnose an abnormality in the external output signal. When the second pattern of pseudo signals is output, the switching means 15 selects the input on the detecting means 14 side, so that the detection signal from the detecting means 15 passes through the switching means 15 and is input to the indicating means 16, 17, . It is supplied to the SM and specifies a predetermined physical quantity. If the indicating means is abnormal, the predetermined value will not be indicated, and thereby a failure of the indicating means can be diagnosed.

F. Example One embodiment will be described with reference to FIGS. 1 and 2.

In Figure 1, which shows the overall configuration of the self-diagnosis circuit, 11 is a vehicle speed sensor, which outputs a pulse (sensor signal) corresponding to the vehicle speed.
Output. This vehicle speed pulse is waveform-shaped by a waveform shaping circuit 12 and inputted to a frequency counter 14 via an OR gate 13. The 0 frequency counter 14 counts vehicle speed pulses input within a predetermined time and generates a signal (detected) corresponding to the vehicle speed. signal). The changeover switch 15 has two input terminals A.

B, an output terminal C, and a control terminal S that selectively switches either input terminal A or B. When the control terminal S is at a high level, the input terminal B is at a low level, and when the control terminal is at a low level, the input terminal A is switched.
are selected respectively. The cross coil drive circuit 16 supplies a drive signal to the cross coil 17 in order to drive the pointer ID of the speedometer SM based on the signal input from the changeover switch 15.

On the other hand, the output of the OR gate 13 is also input to the frequency dividing circuit 18. This frequency dividing circuit 18 outputs a vehicle speed signal a obtained by dividing the vehicle speed pulse by a predetermined frequency division ratio to the vehicle speed detection circuit 19 and also outputs it to other systems. The vehicle speed detection circuit 19 sets its output to a high level when the vehicle speed signal a corresponds to the vehicle speed 6]as/h. Note that this vehicle speed detection circuit 19 is effective only in a self-diagnosis mode, which will be described later.

Further, the output of the frequency counter 14 is also input to a 10 km/h signal output circuit 20. This 10 km/h signal output circuit 20 sets its output C to a high level when the signal from the frequency counter 14 indicates a vehicle speed of 10 kIa/h or less. The output of the vehicle speed detection circuit 19, 101 m/h signal output circuit 20.

C is the output of two OR gates 21, and the output d of the OR gate 21 is input to one input terminal of an AND gate 22. The output of the frequency counter 14 is input to the other input terminal of the AND gate 22.

Furthermore, in FIG. 1, 23 is a self-diagnosis control circuit;
It is started by turning on the self-diagnosis mode switch 24, sets the control signal CKI supplied to the switching control terminal S of the changeover switch 15 to a low level, and sends a start signal to the pseudo vehicle speed pulse generation circuit 25. When the self-diagnosis mode switch 24 is off, this control signal CKI becomes high level. The output of the pseudo vehicle speed pulse generation circuit 25 is used as the other input of the OR gate 13, and the second
As shown in Figure (a), a pseudo vehicle speed pulse (first pattern of pseudo signal) P9.corresponds to a vehicle speed of 5 kii/h. Pseudo vehicle speed pulse P, corresponding to a vehicle speed of 60 km/h. , vehicle speed 1
Pseudo vehicle speed pulse (second pattern of pseudo signal) P1□ corresponding to 201a*/h.

are output sequentially and periodically. These pseudo vehicle speeds are not limited to these numerical values, and the order in which they occur is not limited to the embodiment. The order of P-work 2°→P6°→P may be used, but each vehicle speed pulse and the switching position of the changeover switch 15 need to be related as follows. That is, the pseudo vehicle speed pulse generation circuit 25 generates the pseudo vehicle speed pulse P1□. When outputting
control signal C from the self-diagnosis control circuit 23.
KI is kept at a high level.

In the above configuration, the self-diagnosis mode switch 24 and the self-diagnosis control circuit 23 serve as mode switching means, the vehicle speed sensor 11 serves as a sensor means, the pseudo vehicle speed pulse generation circuit 25 serves as a pseudo signal output means, and the frequency counter 14 serves as a detection means. , crossed coil drive circuit 16. Crossed coil 17. The speedometer SM and the pointer ID serve as the indicating means, and the frequency dividing circuit 18
Alternatively, the 1101a/h signal output circuit 20 constitutes a signal forming means, the AND gate 22 constitutes a gate means, and the changeover switch 15 constitutes a signal switching means.

The operation of this embodiment will be explained with reference to the signal waveform diagram of each part in FIG.

(1) During normal driving In this case, the self-diagnosis mode switch 24 is turned off, a high level signal is applied to the control terminal S of the changeover switch 15, and the input of the input terminal B is selected.

The vehicle speed sensor 11 outputs pulses with a frequency corresponding to the vehicle speed, and the frequency counter 14 counts the pulses generated within a predetermined time (the pulses increase as the vehicle speed increases). A signal indicating the counting result is inputted to the cross coil drive circuit 16 through the changeover switch 15, converted into a predetermined coil drive signal, and supplied to the cross coil 17.

As a result, the pointer ID of the speedometer SM is driven to indicate the detected vehicle speed.

(2) In self-diagnosis mode ■ When the vehicle speed signal, 10km/h signal, and speedometer SM are all normal: When the self-diagnosis mode switch 24 is turned on when the vehicle is stopped, the self-diagnosis control circuit 23 is activated and the control signal CKI is activated. The input terminal A and the output terminal C of the selector switch 15 are connected to each other at a low level.

On the other hand, since the self-diagnosis control circuit 23 supplies a starting signal to the pseudo vehicle speed pulse generation circuit 25, the pseudo vehicle speed pulse generation circuit 25 operates from time t□ to t2 as shown in FIG.
Then, from time t2, a pseudo vehicle speed pulse corresponding to a vehicle speed of 5 km/h is generated, from time t2, a pseudo vehicle speed pulse corresponding to a vehicle speed of 60 b/h is generated, and from ~t4, a pseudo vehicle speed pulse corresponding to a vehicle speed of 120 km/h is sequentially generated. Output periodically.

This pseudo vehicle speed pulse is also input to the frequency counter 14 in the same way as the vehicle speed pulse, and the one frequency counter 14 sequentially outputs counted values according to the vehicle speed. First, a pseudo vehicle speed pulse P5 indicating 5 kra/h is output, so 1 frequency counter 1
The output of the lokm/h signal output circuit 20 (
The 10kIl/h signal) C becomes high level, and the AND gate 22 is enabled.

As a result, 1 frequency counter 14 outputs 5km/
A count value indicating h is supplied to the cross coil drive circuit 16 via the AND gate 22 and the changeover switch 15, so that the pointer ID of the speedometer SM indicates 5 km/h.

On the other hand, the pseudo vehicle speed pulse is also supplied to the frequency dividing circuit 18, frequency-divided, and input to the vehicle speed detection circuit 19. Following the pseudo vehicle speed pulse P, a pseudo vehicle speed pulse P indicates a vehicle speed of 60 km/h. is output, the output of the vehicle speed detection circuit 19 (
The vehicle speed signal) b goes high, the output C of the 10 kni/h signal output circuit 20 goes low, and the AND gate 22 is enabled via the OR gate 21 by the output of the vehicle speed detection circuit 19. When the frequency counter 14 outputs a count value indicating 60 km/h, this output is input to the cross coil drive circuit 16 through the AND gate 22 and the changeover switch 15, so that the pointer ID of the speedometer SM becomes 60 km/h. Instruct h.

Furthermore, a pseudo vehicle speed pulse P□2 indicating a vehicle speed of 120 km/h
o is output, the self-diagnosis control circuit 23 receives the control signal C from the control signal from the pseudo vehicle speed pulse generation circuit 25.
KI is set to high level, and the selector switch 15 is set to input terminal B.
is selected. Therefore, the count value indicating 120 km/h output from the frequency counter 14 is the changeover switch 1.
5 to the cross coil drive circuit 16, thereby setting the speedometer SM pointer ID to 120kn+/h.
instruct. At this time, the 1100k/h'f alarm also sounds to indicate that the vehicle speed has exceeded 1100k/h.

Note that if the 1100k/h alarm does not sound, the abnormality can be diagnosed.

■If the vehicle speed signal is abnormal: Pseudo vehicle speed pulse P 59 psot indicating 5kl/h, 60km/h, 120km/h Speedometer 98M (1) pointer IO is 5b/h, 120k by psot Pi2Q
If 60 km/h is not specified sequentially in m/h, the vehicle speed signal can be diagnosed as abnormal.

■If the 10km/h signal is abnormal, Speedometer SM pointer ID is 60km/h.

If 120km/h is sequentially indicated and only 5-/h is not indicated, the 10km/h signal can be diagnosed as abnormal.

■If Speed Two 93M is abnormal, Speedometer SM pointer-ID is 5km/h.

If neither 60 km/h nor 120 km/h is indicated, it can be diagnosed that the speedometer SM is abnormal.

In this way, it is possible to diagnose abnormalities in the signals of each part and the indicating device from the deflection pattern of the pointer in the self-diagnosis mode.

The present invention can also be applied when the external output signal is either a vehicle speed signal or a 10 km/h signal.

Further, the speedometer drive method is not limited to the crossed coil method, and various other methods may be used. Furthermore.

The present invention is also applicable to various indicating devices that indicate physical quantities other than vehicle speed.

G0 Effects of the Invention According to the present invention, a failure of the indicating means itself, such as a speedometer, is diagnosed based on the indicated value of the indicating means, and a sensor signal (for example, It is also possible to diagnose external output signals (e.g., 10 km/h signal) that are formed based on the vehicle speed pulse (vehicle speed pulse), so it is possible to diagnose the external output signal (e.g., engine electronic control unit) without installing a separate display device. It is possible to quickly and accurately diagnose whether the external output signal itself is malfunctioning or the external output signal itself is malfunctioning.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 (a) to (f) show one embodiment,
Figure 1 is a block diagram showing the overall configuration, Figures 2 (a) to (
) is a signal waveform diagram of each part. 11: Vehicle speed sensor 14: Frequency counter 15: Changeover switch 16: Cross coil drive circuit 17: Cross coil 18: Frequency dividing circuit 19: Vehicle speed detection circuit 20: 1101a/h signal output circuit 21 Nior gate 22: AND gate 23: Self-diagnosis Control circuit 24: Self-diagnosis mode switch 25: Pseudo vehicle speed pulse generation circuit Patent applicant: Nissan Motor Co., Ltd. Patent attorney Norihiro Nagai

Claims (1)

[Scope of Claims] Mode switching means for switching between a self-diagnosis mode and a normal mode; a sensor means for outputting a sensor signal according to a physical quantity of an object to be indicated; a pseudo signal output means for outputting a pseudo signal having the first and second patterns; a detection means for outputting a detection signal corresponding to the magnitude of the physical quantity based on the sensor signal or the pseudo signal; an instruction means for instructing a value corresponding to the physical quantity; a signal forming means for forming an external output signal to be outputted to the outside in order to perform control according to the physical quantity based on the sensor signal or pseudo signal; gate means that allows the detection signal to pass only when the signal and the detection signal are input and the external output signal is normally output; two detection signals are input, and when the first pattern of the pseudo signal is output in the self-diagnosis mode, the detection signal from the gate means is selected, and the second pattern of the pseudo signal is output. The present invention is characterized by comprising a signal switching means for selecting a detection signal from the detection means and inputting it to the instruction means when in the normal mode, and for selecting a detection signal from the detection means and inputting it to the instruction means when in the normal mode. A self-diagnosis circuit for the indicating device.