JPH05215580A - Abnormality detector of pulse generator - Google Patents

Abstract

PURPOSE:To detect an abnormal state automatically by comparing an electrical signal with a first threshold for obtaining the corresponding first electrical signal output, comparing it with a second threshold which is lower than the first electrical signal output for obtaining the corresponding second threshold, comparing the corresponding first electrical signal output with the corresponding second threshold for obtaining a difference in reference to the corresponding second electrical signal, and then judging whether the difference is within a specified allowable range or not. CONSTITUTION:A contact-type encoder is provided with a first comparison means with a comparator 5 which compares an electrical signal of a detection part 4 with a first threshold and a first counter 6 which counts the number of electrical signals exceeding the threshold and then outputs a first count value, a comparator 7 which makes comparison with a second threshold which is smaller than the first threshold of electrical signal, a second comparison means which consists of a second counter 8, and a self-diagnosis CPU 9, thus enabling to judge whether the difference between the first and second count values is within a specified allowable range or not, an error signal is output when the range is exceeded, and then an abnormality signal is output when the count exceeds a specified count by integrating the number of error signal outputs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse generating device such as a contact encoder or an optical encoder, and more particularly to an abnormality detecting device for detecting an abnormal state thereof.

[0002]

2. Description of the Related Art In recent years, electronically controlled fuel injection devices have come to be widely used for controlling the fuel injection amount in, for example, automobiles. For this purpose, a contact encoder, an optical encoder or the like that electrically detects the operation amount of the throttle lever and generates a pulsed electric signal is used.

This type of contact type encoder is constructed by including a brush mounted on an interlocking body that interlocks with the operation of an operating body such as a pedal, and a substrate having a contact with which the brush can periodically come into contact. When the operating body is operated and the brush slides on the substrate, a pulse signal corresponding to the position of the brush on the substrate is output. On the other hand, the optical encoder is configured to include a code plate attached to the interlocking body that interlocks with the operation of the operating body, and a light emitting element and a light receiving element that are arranged at opposing positions via the code plate. When the body is operated and the code plate rotates, the irradiation light from the light emitting element to the light receiving element is periodically blocked by the code plate, so that the light receiving element outputs an electric signal.

[0004]

By the way, in the above-mentioned conventional contact type encoder, foreign matter such as abrasion powder is caught between the brush and the contact due to abrasion during sliding of the brush, and the electrical signal is electrically generated at the ON portion. Since contact failure occurs, there is a problem that the ON portion of the electric signal is finally lost and detection becomes impossible. Further, in the optical encoder, the light path is blocked due to a decrease in luminance of the light emitting element due to aging, a decrease in sensitivity of the light receiving element, or accumulation of foreign matter such as dust,
There is a problem that it is difficult to detect the ON portion of the electric signal.

The present invention has been made in view of the situation in the prior art as described above, and an object thereof is to provide a pulse generator capable of automatically detecting that an abnormal state has occurred in a pulse generator such as an encoder. To provide.

[0006]

In order to achieve this object, the present invention provides an abnormality detecting device for a pulse generator which outputs an electric signal to a main body system, wherein the electric signal has a predetermined first threshold value. First comparing means for comparing and outputting a corresponding first electric signal, and comparing the electric signal with a predetermined second threshold value smaller than the first threshold value, and comparing the electric signal with a predetermined second threshold value. Second comparison means for outputting two electric signals and a difference between the first electric signal and the second electric signal are obtained, and it is determined whether or not the difference between the electric signals is within a predetermined allowable range. And an error detection circuit for judging.

[0007]

The electric signal output corresponding to the contact between the brush and the contact is compared with the predetermined first threshold value by the first comparison means, and the first threshold value is compared by the first counter. A first count value is output by counting the number of times the electrical signal is exceeded. Similarly, the electrical signal is compared with a predetermined second threshold value smaller than the first threshold value by the second comparing means, and the electrical signal exceeding the second threshold value is determined by the second counter. And outputs the second count value. For example, when using a contact encoder, noise is generated due to poor electrical contact between the brush and the contact, the noise level exceeds the second threshold value, and the noise level exceeds the first threshold value. If the threshold is not exceeded,
Since a difference occurs between the first count value and the second count value, whether or not the difference is within a predetermined allowable range is determined by the error determining means, and an error signal is output when the difference exceeds the allowable range. Then, the number of times the error signal is output is integrated by the integrating means. After that, the abnormality detection means detects that the output count has exceeded a predetermined number and outputs an abnormality signal.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the pulse generator of the present invention is applied to a contact type encoder will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an abnormality detecting device for a pulse generator according to the present invention, FIG. 2 is a sectional view showing a main configuration of a contact encoder, and FIG. 3 is an abnormality detecting device for the pulse generator shown in FIG. FIG. 4 is a characteristic diagram of an electric signal containing no noise, FIG. 5 is a characteristic diagram of an electric signal containing noise, and FIG. 6 is a process of comparing the electric signal of FIG. 4 with a first comparator. FIG. 7 is a characteristic diagram showing results, and FIG. 7 is a characteristic diagram showing processing results obtained by comparing the electric signals of FIG. 4 with a second comparator.
8 is a characteristic diagram of an electric signal containing significant noise, FIG. 9 is a characteristic diagram showing a processing result obtained by comparing the electric signal of FIG. 8 with a first comparator, and FIG. 10 is a second comparison of the electric signal of FIG. It is a characteristic view which shows the process result compared with the container.

As shown in FIG. 2, a contact encoder generally moves in conjunction with the movement of a contact 2 provided on a substrate 1 made of an insulator at a predetermined interval in the circumferential direction and an operating body (not shown). The detection unit 4 is composed of a brush 3 that slides on the substrate 1.

The contact encoder of this embodiment is
As shown in FIG. 1, comparison means for comparing the electric signal output from the detection unit 4 with a predetermined first threshold value, for example, the comparator 5 and the number of times the electric signal exceeds the first threshold value is output. Comparing the electric signal with a predetermined second threshold value which is smaller than the first threshold value, and a first comparing means having a first counter 6 for counting Second comparing means including: a comparator 7 for counting the number of output times of the electric signal exceeding the second threshold value and outputting a second count value. Self-diagnosis CP connected to these counters 6 and 8
U9 and. The self-diagnosis CPU 9 determines whether the difference between the first count value and the second count value is within a predetermined allowable range, and outputs an error signal when the difference exceeds the allowable range. The self-diagnosis CPU 9 comprises a judging means, an integrating means for integrating the number of times of outputting the error signal, and an abnormality detecting means for detecting that the number of times of outputting exceeds a predetermined number and outputting an abnormal signal. The self-diagnosis information is output to the main body system CPU 10.

The electric signal output from the detector 5 is
Normally, as shown in FIG. 4, it does not include noise. However, when a foreign substance such as abrasion powder is caught between the brush 3 and the contact 2 to cause a slight electrical contact, the electrical signal includes noise as shown in FIG. 5, for example.
In the comparator 5 of FIG.
And the electric signal is compared to output the processing result shown in FIG. Further, the second comparator 7 also compares the predetermined second threshold value shown by the chain double-dashed line 5b in FIG. 5 with the electric signal and outputs the processing result shown in FIG. Further, when a considerably large amount of electrical contact is made between the brush 3 and the contact 2, the electrical signal output from the detection unit 5 contains significant noise as shown in FIG. There is a very noticeable difference between the processing result (shown in FIG. 9) and the processing result (shown in FIG. 10) by the second comparator 7.

In this embodiment, the electric signal output from the detector 5 is adapted to perform self-diagnosis according to the processing procedure shown in FIG. For example, when the electric signal includes noise as shown in FIG. 5, first, in step S1, the electric signal is compared with the first threshold value shown by the chain double-dashed line 5a in FIG. 5 by the first comparator 5. 6, the processing result shown in FIG. 6 is output, and the first counter 6 counts the number of times the electric signal exceeds the first threshold value and outputs the first count value. Similarly, the second comparator 7 compares the second threshold value shown by the chain double-dashed line 5b in FIG. 5 with the electric signal and outputs the processing result shown in FIG. The number of times of output of the electric signal exceeding the second threshold value is counted and a second count value is output. At this time, the noise part 5n in FIG. 5 exceeds the second threshold value shown by the chain double-dashed line 5b and does not exceed the first threshold value shown by the chain double-dashed line 5a. The comparator 5 does not output the electric signal corresponding to the part 5n of the noise.
Only the comparator 7 of FIG.
Since the electric signal 7n corresponding to n is output, as a result,
A difference occurs between the first count value and the second count value.

Then, in step S2, the self-diagnosis CPU 9
It is determined whether the difference between the first count value and the second count value is within a predetermined allowable range, and if it is within the predetermined allowable range, the first comparator 5 is used as step S3. The processing result in (1) is output to the main body system CPU 10 as an encoder output. On the other hand, when the difference exceeds the allowable range, the self-diagnosis CPU 9 outputs an error signal, and the number of times the error signal is output is integrated in step S4. Then, in step S5, it is determined whether or not the output count exceeds a predetermined count. If the output count exceeds the predetermined count, step S6 is performed.
The self-diagnosis CPU 9 outputs an abnormal signal to the main body system CPU 10. Based on this abnormality signal, for example, the main body system CPU 10 switches from the normal mode to the fail-safe function mode in which the encoder output is ignored. In addition, the procedure S5 described above.
If the number of output of the error signal does not exceed the predetermined number, the detection operation as the encoder is continued.

In the embodiment thus constructed, when the noise occurrence frequency is relatively low as shown in FIG. 5, the detecting operation as the encoder is continued and the brush 3 is used.
It is possible to automatically detect the occurrence of an abnormal state when the frequency of noise generation becomes relatively high as shown in FIG. 7 due to the poor electrical contact between the contact 2 and the contact 2.

In this embodiment, it is determined in step S5 of FIG. 3 whether or not the number of times the error signal is output exceeds a predetermined number, and if it exceeds the predetermined number, an abnormal signal is output to the main system CPU 10 in step S6. However, as shown in FIG. 11, it is further determined in step S5 whether or not the number of times the error signal is output exceeds a predetermined number. If the number of output times does not exceed the predetermined number, the first abnormal signal is output in step S6a. It is also possible to output the second abnormal signal to the main body system CPU 10 as step S6b when the error signal is output to the main body system CPU 10 and the detection operation as the encoder is continued, while the number of output times of the error signal exceeds a predetermined number. .. Then, based on the first abnormal signal, for example, an alarm signal prompting replacement of the detection unit 5 is output, and based on the second abnormal signal, for example, a normal mode is switched to a fail-safe function mode such as ignoring the encoder output. You may make it switch.

In the present embodiment, the case has been described in which the number of times each of the electric signals is output is calculated and the difference therebetween is obtained. However, the difference between the electric signals is output using, for example, a subtracter, It is also possible to count the number of outputs.

Furthermore, in the present embodiment, the case where the present invention is applied to the contact type encoder has been described, but the present invention can also be applied to other pulse generators such as an optical encoder.

[0018]

Since the present invention is configured as described above, it is possible to automatically detect that an abnormal state has occurred in a pulse generator such as an encoder. Therefore, it can be grasped whether or not the electric signal is reliable during use as the pulse generator, and the reliability with respect to the service life can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an abnormality detection device for a pulse generator according to the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a main part of a contact encoder.

FIG. 3 is a flowchart showing a processing procedure of an abnormality detection device of the pulse generation device of FIG.

FIG. 4 is a characteristic diagram of an electric signal containing no noise.

FIG. 5 is a characteristic diagram of an electric signal including noise.

FIG. 6 is a characteristic diagram showing a processing result obtained by comparing the electric signals of FIG. 4 with a first comparator.

FIG. 7 is a characteristic diagram showing a processing result obtained by comparing the electric signals of FIG. 4 with a second comparator.

FIG. 8 is a characteristic diagram of an electric signal containing significant noise.

9 is a characteristic diagram showing a processing result obtained by comparing the electric signals of FIG. 8 with a first comparator.

10 is a characteristic diagram showing a processing result obtained by comparing the electric signals of FIG. 8 with a second comparator.

FIG. 11 is a block diagram showing an application example of the abnormality detection device of the pulse generation device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Contact point 3 Brush 4 Detection part 5 1st comparator (1st comparison means) 6 1st counter 7 2nd comparator (2nd comparison means) 8 2nd counter 9 Self-diagnosis CPU

Claims (1)

[Claims] 1. An abnormality detection device for a pulse generator that outputs an electric signal to a main body system, comparing the electric signal with a predetermined first threshold value, and outputting a first electric signal corresponding to the first threshold value. And a second comparing means for comparing the electric signal with a predetermined second threshold value smaller than the first threshold value and outputting a second electric signal corresponding thereto. A pulse generation, comprising: an error detection circuit that obtains a difference between a first electric signal and the second electric signal and determines whether the difference between the electric signals is within a predetermined allowable range. Device abnormality detection device.