JPH02128118A - Detector - Google Patents

Abstract

PURPOSE:To detect a trouble of a detector by connecting a comparison means on the output side of detection working sections to compare output signals therefrom so an output signal corresponding to a comparison value thereof is outputted to an error output terminal. CONSTITUTION:When a limit switch 2 is turned ON, a contact 3a is turned ON in linkage therewith while a contact 3b turned OFF and output signals thereof are outputted to output terminals 4a and 4b. At this point, output signals from the contacts 3a and 3b are inputted into an exclusive OR element 5. Then, when contacts 3a and 3b are both normal, an input signal to the element 5 is 'high' and 'low' and hence, an output signal therefrom goes to 'high', a normal signal 'high' is outputted at an error output terminal 6. When one of the contacts 3a and 3b is broken down because of a fusing, burning out or the like, a signal to be inputted into the element 5 goes 'high', 'high' or 'low' or 'low'. Thus, an output signal moves to 'low' and an error signal 'low' is outputted at the terminal 6.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to detection switches such as limit switches, pressure switches, and proximity switches, encoders for detecting the position of rotating bodies, and monitors for temperature, pressure, vibration, etc. It relates to detectors such as analog sensors for

[Conventional technology]

The various types of detectors mentioned above are used in industrial machinery such as press machines and machine tools, as well as plant systems, etc., but conventional detectors of this type cannot detect when each detector itself has malfunctioned. The configuration made it impossible to do so.

[Problem to be solved by the invention]

Therefore, in each machine, in the process of issuing a certain command from the controller and using the detector to check whether the operation has been performed, it is possible that this detector is malfunctioning and a predetermined period of time has elapsed since the controller issued the operation command. If the detector does not operate even after passing through, it is assumed that it is an error even though the detector is malfunctioning, and the operation command is canceled.

When an error occurs in the operation of a machine, the causes can be broadly classified into failures in the detector itself, and abnormal motion in the mechanical system.As mentioned above, with conventional detectors, Because it was not possible to detect the failure of the machine, it was not possible to distinguish between the above failures, and the only way to distinguish between them was to have a human go close to the machine to determine the failure, which took time.

In addition, malfunctions in the above-mentioned detectors include, for example, in the case of limit switches, pressure switches, etc., the contacts are fused or burnt out, and in the case of encoders or analog sensors, it is an abnormality in the detection part, etc. .

The present invention has been made in consideration of the above, and an object of the present invention is to provide a detector capable of detecting a failure in each detector itself and performing more advanced failure diagnosis.

[Means to solve the problem]

In order to achieve the above object, the detector according to the present invention is a detector such as a limit switch, a pressure switch, an encoder, an analog sensor, etc., which is provided with a plurality of detection actuation parts such as contacts and sensor parts, and at least one of them is provided with a plurality of detection actuation parts such as contacts and sensor parts. The detection actuation parts are connected to the output terminals, and comparison means is provided on the output side of each detection actuation part to compare the output signals from each detection actuation part and output an output signal according to the comparison value to the error output terminal. It has a connected configuration.

[For production]

During operation of the detector, when one of the plurality of detection actuators fails, an error signal is taken out from the comparison means, and a failure of the detector itself is detected.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

Figure 1 shows the case of a limit switch. The contact part 3 of the limit switch 2 connected to the input terminal 1 is composed of two contacts 3a and 3b, and the output terminals 4a and 4b are connected to the output side of each. has been done. Both contacts 3a,
One of the contacts 3b is an a contact, and the other is a b contact, and each of them is adapted to switch in conjunction with the operation of the limit switch 2. Further, an error output terminal 6 is connected to the output side of both contacts 3a and 3b via an exclusive OR element 5.
is connected.

In the figure, C1 is a capacitor, and R1-R3 are resistors, which are attached to the exclusive OR element 5.

In the above configuration, when limit switch 2 is turned on,
In conjunction with this, the contact 3a on the a contact side of the contact part 3 is turned on,
The contact 3b on the b contact side is turned off, and the respective output signals are output to the output terminals 4a and 4b. Also at this time,
The output signals from both contacts 3a and 3b are sent to exclusive OR element 5.
is also entered. When both contacts 3a and 3b are normal, the input signal to the exclusive OR element 5 is "high" and "low", so the output signal from this is "high", A normal signal "high" is output from the error output terminal 6.

If one of the contacts 3a, 3b fails due to fusion, burnout, etc., the signal input to the exclusive OR element 5 becomes "high".
, "high" or "low", "low", the output signal from this becomes "low", and the error signal "low" is output from the error output terminal 6.

In other words, if a failure occurs in the contacts 3a and 3b, either one of the contacts will turn ON or OFF, and the other contact, which is normal, will turn ON%OFF.
During its operation, there are times when the input signals to the exclusive OR element 5 become the same, and at this time, the error signal "low" is outputted from this element 5.

Note that both contacts 3a are broken due to both contacts.

3b is fixed in the state shown in FIG. 1 or vice versa, the failure cannot be detected.
There is no problem because the probability that both a and 3b will fail is small.

Further, if one of the two contacts 3a, 3b fails, a normal output signal according to the operation of the limit switch 2 is output to the output terminal connected to the other normal contact. The output terminals 4a and 4b do not necessarily need to be provided for each contact, and only one contact may be connected to the output terminal, and the other contact may be connected only to the exclusive OR element 5.

Furthermore, in the above embodiment, the contact 3a of the contact portion 3.

3b shows an example in which one of them is an a contact and the other is a b contact, but both contacts may be an a contact or a b contact. However, in this case, the error signal from the error output terminal 6 is "high".

FIG. 2 shows the case of an encoder, in which two encoder parts 8 a are attached to the rotating shaft 8 of the motor 7.

8b are connected in parallel, and both encoders 8a
, 8b detect the rotational position of the motor 7 in parallel. The output side of one of the encoder sections 8a and 8b is connected to the encoder output terminal 9, and both encoder sections 8a and 8b are connected to the encoder output terminal 9.
The output side of b is connected to an error output terminal 11 via an exclusive OR element 10.

In this configuration, the rotational position of the motor 7 is detected by two encoder sections 8a and 8b, and an output signal from one of the encoder sections 8a is taken out from an encoder output terminal 9. On the other hand, at this time, both encoder sections 8a and 8b
The output signal from is input to the exclusive OR element 10. When both encoder sections 8a and 8b are outputting normal signals, the respective inputs to the exclusive OR element 10 are "high", "high" or "low", "low", Therefore, the output from this element 10 is "low",
It is determined that both encoder sections 8a and 8b are normal.

If one of the encoder sections 8a, 8b fails and its output signal is fixed at "high" or "low" or turns ON or OFF.
out of synchronization, the output signal from the exclusive OR element 10 becomes "high" when the logic is opposite to the other normal signal, and this is output from the error output terminal 11, causing the rotation of the motor 7. It is determined that the position detection encoder has failed.

FIG. 3 shows the case of an analog sensor that detects temperature, pressure, etc., and has two sensor sections 11a.

11b are provided in parallel, and the amplifier circuits 12a and 1 are connected to each other.
2b is connected. And one of the amplifier circuits 1
The output of the amplifier circuit 2a is connected to the sensor signal output terminal 13, and the output sides of both amplifier circuits 12a and 12b are connected to the first comparator 14a. Further, this analog sensor has a built-in tolerance setting device 15 for setting the tolerance of fluctuations in the detected values by the two sensor sections 11a and llb, and the output side of this tolerance setting device 15 and the first comparator 14a are connected to the output side of the tolerance setting device 15. The output side of the second comparator 14b is connected to the error output terminal 16.

In this configuration, for example, in the case of a pressure sensor, the same pressure is detected by the two sensor parts 11a and llb, each detection signal is amplified by the amplifier circuits 12a and 12b, and the detection signal is output from one amplifier circuit 12a. The signal is taken out to the sensor signal output terminal 13. At this time, both sensor parts 1
1a.

The detection signal from 11b is compared in absolute value by the first comparator 14a, and the comparison value and the set value signal from the tolerance setter 15 are compared by the second comparator 14b.

When one of the two sensor sections 11a and llb fails and its output signal no longer exhibits predetermined characteristics, the first comparator 14
The output signal from a greatly changes with respect to the signal from the tolerance setter 15, and the second comparator 14b outputs "high" as an error signal.

In the embodiment shown in FIG. 3 above, if you want to detect a failure in the amplifier circuit section, connect two amplifier circuits to one sensor section, compare the output signals of both amplifier circuits, and change the comparison value. It may also be possible to detect that one of the amplifier circuits has failed.

〔Effect of the invention〕

According to the present invention, a failure of each detector itself can be detected, and more advanced failure diagnosis can be performed. In addition, if the above-mentioned detector is an encoder or an analog sensor, and if an abnormality occurs in the detection results from these, it is usually unclear whether it is a failure of the detector itself or whether the detection target is actually abnormal. Since the detector according to the present invention can distinguish between the two, it is possible to take countermeasures against the abnormality and shorten the time required for recovery.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a circuit diagram of a limit switch, FIG. 2 is a circuit diagram of an encoder, and FIG. 3 is a circuit diagram of an analog sensor. 1 is an input terminal, 2 is a limit switch, and 3a. 3b is a contact, 4a, 4b, 9.13 is an output terminal, 5.1
0 is an exclusive OR element, 6, 11.16 are error output terminals, 8a, 8b are encoders, 11a, llb are sensor units, 12a, 12b are amplifier circuits, 14a, 14b are comparators, 15 is a tolerance setter . Applicant Komatsu Manufacturing Co., Ltd. Representative Patent Attorney Masaaki Yonehara

Claims (1)

[Claims] Detectors such as limit switches, pressure switches, encoders, and analog sensors are provided with multiple detection actuation parts such as contacts and sensor parts, and at least one of them is connected to an output terminal, and each detection actuation part is connected to an output terminal. A detector characterized in that a comparison means is connected to the output side for comparing output signals from each detection operation section and outputting an output signal according to the comparison value to an error output terminal.