JPH05333041A - Sensor switch with diagnosing function - Google Patents

Abstract

PURPOSE:To diagnose the failure of a sensor switch operating by sensor signals easily at low costs from a remote place. CONSTITUTION:The invention is widely applicable to general sensor switches. For instance, a magnetic proximity switch is constituted of a lead switch 3 and a diagnosing coil 5. An object to be detected has a permanent magnet 6 built therein to operate the lead switch. The lead switch 3 works as a sensor switch when the permanent magnet 6 approaches. The sensor switch is diagnosed in the simulative operation of the lead switch 3 when the diagnosing coil 5 is turned ON. Moreover, if true diagnosing coil 5 is connected in series with the lead switch 3, two-wire wiring becomes possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor switch with a diagnostic function for diagnosing and detecting a failure of a sensor switch operated by a sensor signal in a use state, and particularly used for safety, disaster prevention, crime prevention, etc. to detect an abnormality. It relates to a target sensor switch.

[0002]

2. Description of the Related Art A switch that operates (ON / OFF) by detecting displacement, proximity, contact, etc. of an object, a switch that operates depending on whether a pressure detected by a pressure sensor is higher or lower than a predetermined pressure, and various other types. Switches that operate according to sensor signals will be collectively referred to as sensor switches.

Sensor switches are used in many applications. A sensor switch which is used for control or the like and which operates frequently can detect malfunction of the sensor switch relatively quickly and easily. In other words, malfunctions, and thus failures, can be diagnosed and detected by events such as not operating even after a stipulated time or not operating under the condition that it should operate.

In safety, disaster prevention, crime prevention, etc., a sensor switch that operates when an abnormality occurs and detects the abnormality does not always operate. The failure of the sensor switch not to operate when an abnormality occurs has very serious consequences. Moreover, it is difficult to detect a failure of a sensor switch that does not always operate unless the diagnosis is positively made.
It is necessary to confirm that there is no failure by methods such as periodical failure diagnosis.

However, in order to diagnose the failure of the sensor switch, it is necessary to actually operate the sensor switch.

When a large number of sensor switches are scattered and installed in a large area, the operation of the sensor switches is often collected and centralized by a transmission system. When the sensor switch operates, it can be immediately detected at a place where centralized control is performed.

However, when performing a failure diagnosis, it is necessary to go to a place where the sensor switch is installed and actually operate the sensor switch to make a diagnosis. This requires a great deal of manpower and time. If the time interval for failure diagnosis is increased in order to save manpower and time, failure detection will be delayed and system reliability will be reduced.

Further, it is not always easy to actually operate the sensor switch for failure diagnosis. In many cases, this cannot be done unless equipment and circuits for diagnosis are prepared and placed in advance.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to facilitate a failure diagnosis by operating a sensor switch from a remote location, and to significantly reduce manpower and time required for the failure diagnosis.

However, in order to truly operate the sensor switch remotely, a large-scale device or circuit is generally required. It will be too expensive and not economically feasible. Therefore, it is desirable to simply and cheaply diagnose the sensor switch by simulating the operation. It is more desirable if the simulated operation can be performed remotely.

However, the diagnosis by the simulated operation cannot detect all the failures of the sensor switch.
Depending on the type of failure, there is something that cannot be found depending on the diagnosis even though the failure is actually occurring.

On the other hand, there are some faults that can be easily detected without relying on diagnosis by simulated operation. Of course, this kind of fault does not have to be found by diagnosis. Further, there are some faults whose occurrence probability is relatively very small, even if the faults cannot be discovered without diagnosis. If a fault with a high probability of occurrence can be detected with certainty, even if it is not possible to find a fault with a low probability of occurrence, it can be considered as a sufficient fault diagnosis in practical use.

The present invention is highly practical and can be remotely controlled by an appropriate simulated operation for operating the sensor switch.
It is an object of the present invention to realize a sensor switch that can perform failure diagnosis easily and at low cost.

[0014]

A feature of the present invention for solving the above-mentioned problems is that a sensor coil has a diagnostic coil and a magnetic piece that is excited and operated by energizing the diagnostic coil. The contact is a sensor switch with a diagnostic function that is activated by the operation of the magnetic piece, and conducts a failure diagnosis of the sensor switch by energizing the diagnostic coil. Furthermore, by energizing the diagnostic coil, the sensor switch This is a sensor switch with a diagnostic function that enables failure diagnosis even if the contact operation of the sensor switch is temporary by storing that operation when the contact operates. In use, when the contact of the sensor switch is normally on, connect the sensor switch and the diagnostic coil in series. The value of the current flowing through the series circuit shall be the value at which the contact of the sensor switch does not operate due to the current flowing through the diagnostic coil during non-diagnosis, and the value at which the contact of the sensor switch operates during the diagnostic, during the diagnosis. The two-wire wiring is performed by adding a permanent magnet or an energized coil so that the contact of the sensor switch is always on in a normal use state of the sensor switch.

[0015]

[Embodiment 1] The present invention will be described below with reference to Embodiment 1. In the first embodiment, the sensor switch is a magnetic proximity switch, and the present invention is applied to this. However, the present invention is not limited to proximity switches,
Widely applied to sensor switches in general.

FIG. 1 shows the configuration of a proximity switch according to the present invention. 1 is a proximity switch for detecting the proximity of an object,
Reference numeral 2 denotes an object whose proximity is detected by the proximity switch. The proximity switch 1 includes a reed switch 3 which is a switch section and a diagnostic coil 5 which is a feature of the present invention. In the reed switch 3, the switch lead wire 4 itself is made of a magnetic material, and the lead wire also serves as a magnetic piece that operates in response to magnetism.

A permanent magnet 6 is embedded in the object 2 whose proximity is to be detected. When the object 2 approaches the proximity switch 1, the magnetic flux of the permanent magnet 6 excites the lead wire 4, and the switch 3 is turned on. Object 2 is proximity switch 1
Further away, the lead wire 4 is no longer excited and the switch 3 is turned off.

On the other hand, when the diagnostic coil 5 is energized, the diagnostic coil 5 is excited and a magnetic flux is generated.

First, consider a case where the object 2 is far away from the proximity switch 1. At this time, the lead wire 4 is in a non-excited state, and the switch 3 is off. When the diagnostic coil 5 is energized, whichever direction the current is,
The lead wire 4 is excited by the magnetic flux generated by the current, and the switch 3 is turned on. That is, by energizing the diagnostic coil 5, the switch 3 operates from off to on. If the switch 3 does not operate from off to on even if the diagnostic coil 5 is energized, it is determined to be a failure.

When the object 2 is close to the proximity switch 1, the lead wire 4 is excited by the permanent magnet 6, and the switch 3 is in the ON state. Consider the case where the diagnostic coil 5 is energized in this state. At this time, the operation differs depending on the direction of the current.

At the lead wire 4, if the magnetic flux generated by the current is in the same direction as the magnetic flux generated by the permanent magnet 6, both magnetic fluxes are added and the switch 3 remains on.

At the lead wire 4, when the magnetic flux generated by the current is in the opposite direction to the magnetic flux generated by the permanent magnet 6,
At the lead wire 4, the magnetic fluxes cancel each other out if they are approximately equal in magnitude. That is, the lead wire 4
Is not excited and the switch 3 is turned off. If this operation is not performed even if the diagnostic coil is energized, it is determined to be a failure.

From the above, at the lead wire 4,
It can be seen that proper diagnosis can be performed by selecting a current in a direction and magnitude such that the magnetic flux generated by energizing the diagnostic coil 5 cancels the magnetic flux generated by the permanent magnet 6. In this case, the switch 3 is operated by energizing the diagnostic coil 5 regardless of whether the object 2 is close to the proximity switch 1 or distant from the proximity switch 1 if there is no failure. Therefore, if the switch 3 does not operate, the failure can be diagnosed and detected.

The above description has been made by taking a proximity switch using a permanent magnet and a reed switch as an example.

When the switch 3 is other than the reed switch, the switch 3 is provided with a magnetic piece that interlocks with the contact. If the contact of the switch 3 is operated by energizing the diagnostic coil 5 and exciting the magnetic piece, the same operation as in the present embodiment is achieved. The present invention can be easily implemented by making the diagnostic coil 5, the magnetic piece, and the contact of the switch 3 have a structure similar to that of a general relay. In a general relay, a polarized relay in which a permanent magnet is incorporated in a magnetic piece is used in order to save the power supplied to the coil and improve the operation reliability. Similar magnetic pieces can be used for the magnetic piece of the present invention.

Even if the principle of operating the contact of the switch 3 by the sensor is other than that by the permanent magnet, the force for operating the switch 3 by the sensor and the force for operating the switch 3 by energizing the diagnostic coil 5 The present invention can be implemented if the relationship with the above can be made the same as that of the present embodiment.

For example, in the case of a sensor switch that operates a switch by displacement, the present invention cannot be applied to the principle of forcibly operating the switch by displacement. However, if the principle is to transmit the displacement to the switch via the spring and operate the switch 3 by the force of the spring,
The present invention can be applied. That is, the force exerted by the displacement as the sensor switch and the force exerted by the diagnostic coil 5 can be balanced in the switch 3 (in this case, not the reed switch) as in the first embodiment.

In order to make a diagnosis in the first embodiment, it is sufficient to energize the diagnosis coil 5 and check the operation of the switch 3. In either case, the diagnosis can be easily performed remotely by extending the wiring. The wiring of the switch 3 is originally the wiring itself of the sensor switch. Therefore, the diagnosis can be performed remotely only by adding wiring for energizing the diagnosis coil.

The switch 3 operates by performing the diagnosis. Therefore, measures such as adding a circuit are performed as necessary so that the alarm is not issued and the control device is not operated by the operation of the switch 3 at the time of diagnosis. These procedures can be performed easily.

[0030]

Second Embodiment Depending on the principle of the sensor, a coil may be used for the operation of the switch 3 by the sensor. Also in this case, the present invention can be implemented by the method of the first embodiment. However, the second embodiment is simpler.

In FIG. 2, 11 is a sensor. For example, when the output power of the sensor is weak and the direct contact cannot be operated like a pressure switch using a piezoelectric element, it is necessary to amplify the output signal of the sensor. The output signal of the sensor 11 is input to the amplifier 13 via the switch 12, and the output amplified by the amplifier 13 is
The coil 14 is driven. Depending on the output value of the sensor 11,
The coil 14 is switched between energized and non-energized, and the contact 15 with the magnetic piece is operated. The above sensor 11 to the contact 15 with the magnetic piece constitutes a sensor switch.

On the other hand, the other end of the switch 12 is connected to the switch 16, and the other end of the switch 16 is connected to the simulated input 17 and the simulated input 18. The simulated input 17 produces an output value of the sensor 11 corresponding to the non-energization of the coil 14.
The simulated input 18 is the sensor 11 corresponding to the energization of the coil 14.
Produces the output value of.

When the switch 12 is tilted to the switch 16 side,
Diagnostic status. At that time, the switch 16 controls energization / de-energization of the coil 14. Diagnosis can be performed by reversing the energization / de-energization of the coil 14 in the diagnosis state to the energization / de-energization of the coil 14 when operating as the sensor switch. The switches 12 and 16 do not have to be contact switches. A semiconductor switch may be used.

In the second embodiment, the coil 14 is
It is used both as an operating coil originally for the sensor switch and as a diagnostic coil. As a result, the coil 14 and the magnetic piece-attached contact 15 constitute a normal relay.

In the second embodiment, the switch 12
Is on the input side of the amplifier 13, but may be on the output side of the amplifier 13. However, by inserting the input side of the amplifier 13, it is possible to diagnose the failure of the amplifier 13.

[0036]

Third Embodiment For more accurate diagnosis, it is necessary to operate the entire sensor switch for diagnosis. However, in general, it is often sufficient if the diagnosis can determine that the switch portion is a failure when the switch portion does not operate when it should operate. Particularly in the case of a sensor switch having a simple structure such as the magnetic proximity switch in the first embodiment, it is sufficient to diagnose whether or not the contact of the switch operates normally.

The failure that occurs when the switch is on is mainly due to the welding of the contacts and the like, which does not turn off when the contacts should be turned off. The main cause of the failure when the switch is off is that the contact is not turned on when it should be turned on due to poor contact. Therefore, if this can be confirmed, it can be considered that the main purpose was achieved.

At the time of diagnosis, when the contact is on,
It is sufficient to confirm that the contact is temporarily turned off, and it is not necessary to confirm that the contact is continuously off. Further, when the contact is off, it is sufficient to confirm that the contact is temporarily turned on, and it is not necessary to confirm the continuation of the on state.

The third embodiment is based on the above idea. The configuration is shown in FIG. Reference numeral 1 is the proximity switch 1 shown in the first embodiment. Since the configuration is the same as that of the first embodiment, the inside is not shown. For objects that should detect proximity,
Since it is the same as the object 2 of the first embodiment, it is not shown. 22
Is an input for energizing the diagnostic coil. 23
Is a flip-flop connected to the output of the contact of the proximity switch and stores the operation of the contact. Reference numeral 24 is a storage output of the flip-flop 23, and 25 is a reset input for resetting the flip-flop.

In the first embodiment, in order to make a correct diagnosis, the permanent magnet 6 is provided at the position of the lead wire 4.
The magnetic flux due to and the magnetic flux due to energization when the diagnostic coil is energized must have opposite directions and substantially equal magnitudes.

However, the distance between the proximity switch 1 or the lead wire 4 and the object 2 or the permanent magnet 6 continuously changes. When the distance between the proximity switch 1 and the object 2 is within a certain range, the switch 3 is turned on. In a model in which the range in which the switch 3 is turned on is wide, the range change in the magnetic flux density at the location of the lead wire 4 by the permanent magnet 6 at which the switch 3 should be turned on is also considerably large.

In such a situation, even when the diagnostic coil 5 is energized when the object 2 is in close proximity and the switch 3 is on, the switch 3 operates in an unstable manner and can be stably turned off. Can be difficult. However, the diagnostic coil 5
It is possible to turn off the switch 3 at least temporarily by increasing the value of the current flowing through the switch 3. Therefore, when the switch 3 is turned off at least temporarily, it may be diagnosed that the switch 3 operates normally. The switch 3 is temporarily turned off due to other reasons, but the same applies to the case where the switch 3 is not stably turned off.

The diagnostic procedure is shown below. Prior to the start of diagnosis, the flip-flop is first reset by the reset input 25. The input 22 then energizes the diagnostic coil. If the switch 3 is temporarily turned off, the flip-flop 23 is set. Diagnosis can be made by checking the output 24 of the flip-flop.

Even when the diagnostic coil 5 is energized and the operation of the switch 3 becomes unstable when the switch 3 is off, the switch 3 is temporarily turned on by the same method. The flip-flop 23 may be stored.

When it is necessary to diagnose both operations, two sets of flip-flops 23 may be prepared.

The flip-flop 23 and its peripheral circuits do not need to be built in the case of the sensor switch. It may be installed at a remote place, for example, on the side of a device that performs centralized control.

[0047]

Fourth Embodiment In the third embodiment, the operation of the switch 3 becomes unstable due to the relation between the sensor switch and the diagnostic coil. Therefore, the temporary operation of the switch 3 is stored to ensure the diagnosis. To do. On the other hand, there are cases where the operation of the switch 3 at the time of diagnosis is intentionally desired to be a temporary operation. An example of this is shown in FIG. The output of the sensor switch is generally collected by transmission and often managed centrally. This transmission may be performed by individual wiring, but multiple transmission is often used. There are various types of multiplex transmission.

There is a multiplex transmission in which the signal transmission and the power supply for the transmission device can be shared by a common wiring. When this multiplex transmission is used, it is more effective if it serves not only as a power supply for the transmission device but also as a power supply for a sensor or the like connected to the transmission device. in this case,
It is desirable that the current consumption of a sensor or the like connected to the transmission device is as small as possible.

In the sensor switch with a diagnostic function according to the present invention, the current passed through the diagnostic coil 5 may be a short time only during the diagnostic. However, if the operation of the switch 3 is temporary, the energization time can be further shortened.
That is, a short diagnostic diagnosis time is intentionally set so that the operation of the switch 3 becomes temporary.

Further, the current value applied to the diagnostic coil 5 is considerably large. It is effective to reduce this current value. The fourth embodiment is an effective method for shortening the energization time of the diagnostic coil and reducing the peak value of the current.

The structure of the fourth embodiment is shown in FIG. Reference numeral 1 denotes a proximity switch, the inside of which is not shown, as in the third embodiment. Similarly, the object 2 is not shown. Since 22 to 25 are the same as those in the third embodiment, the description thereof will be omitted.

Reference numeral 31 is a power supply for the diagnostic coil, which is supplied from, for example, a transmission device. The power supply 31 is connected to the capacitor 33 via the resistor 32. The other end of the capacitor is connected to ground. Capacitor is resistance 3
Although it is constantly charged through 2, the resistor 32 has a high resistance and the charging current is very small. When the charging is completed, the charging voltage of the capacitor is almost equal to the voltage of the power supply 31. The output of the capacitor 33 is connected to the power supply 22 to the diagnostic coil 5 via the transistor 34. The transistor 34 is normally off, and is turned on for a short time only when the diagnostic coil 5 is energized during diagnosis. Note that this transistor may be another type of switch.

By turning on the transistor,
The electric charge charged in the capacitor 33 flows to the diagnostic coil. This current causes the capacitor 33 to be discharged and the voltage to drop, so that the current becomes a temporary pulse. The time width of the current pulse has only to have a time width sufficient for the switch 3 to temporarily operate. The capacity of the capacitor 33 is selected so as to satisfy this. The period in which the transistor is on should be commensurate with the time width of this current pulse.

Even if the switch 3 operates stably when a predetermined current continues to flow through the diagnostic coil, the current is a pulse, so in the fourth embodiment, the switch 3 is operated. The operation is temporary. Further, as shown in the third embodiment, the operation of the switch 3 is originally unstable, and the fourth embodiment can be combined and applied. In any case, the operation of the switch 3 is temporary. Similar to the third embodiment, the operation of the switch 3 is stored in the flip prop 23.

The diagnostic procedure is the same as in the third embodiment. However, after the diagnosis is performed, the capacitor 33 is discharged and the voltage drops. It is necessary to wait for the voltage to be restored by charging through the resistor 32 before the next diagnosis is performed. This charging time depends on the value of the resistor 32. In general, the diagnostic time interval can be sufficiently long. Therefore, the resistance value of the resistor 32 can be made large, and the charging current can be suppressed minutely. If the current pulse time width at the time of diagnosis is 100 msec,
If the average current value of the current pulse is 50 mA and the diagnosis time interval is 10 minutes, the average charging current is 10 μA or less.

[0056]

[Embodiment 5] When a transmission system such as multiplex transmission is not used, the wiring of the sensor switch is an individual wiring. Even when a transmission system such as multiplex transmission is used, as shown in FIG. 5, a plurality of adjacent sensor switches are often collected by individual wiring and placed on the transmission system. Reference numeral 51 is a transmission path of the transmission system, and 52 is a transmission device of the transmission system. The plurality of sensor switches 1 are connected to the transmission device by individual wiring 53.

In any case, it is desirable that the individual wiring can be simplified. According to Example 5, in the present invention,
The operation signal of the sensor switch and the energization of the diagnostic coil can be realized by two-wire wiring.

FIG. 6 shows an example of individual wiring when the present invention is carried out without depending on the fifth embodiment. The sensor switch 1 is connected to the central device 7 by wires (47, 48 and 49). The central device 7 is a device that utilizes the operation of the sensor switch, and is a centralized management device when performing centralized management. Transmission device 52 shown in FIG.
And so on.

The power supply 41 is connected to the ground via the switch 43, the wiring 47, the diagnostic coil 5, and the return wiring 48. At the time of diagnosis, by turning on the switch 43, a current is passed through the diagnosis coil. Further, there is a circuit that is connected to the ground from the power supply 41 via the resistor 45, the wiring 49, the switch 3, and the return wiring 48. By checking the voltage on the output side 46 of the resistor 45,
The on / off state of the switch 3 can be checked. The return wiring 48 is common, but still three wirings are required. Also, if the connection is wrong, it will not work.

The structure of the fifth embodiment is shown in FIG. The power supply 41 is connected to the switching terminal of the switch 43 via the resistor 42, and the voltage between them is taken out from 44.
On the other hand, the power supply 41 is connected to the other switching terminal of the switch via the resistor 45, and the voltage between them is set to 46
Is taken from. This voltage is the flip-flop 23
Entered in. The flip-flop 23 is the third embodiment.
24 and 25 are the same as in the third embodiment.

The other end of the switch 43 is connected to the ground 49 via the wiring 47, the diagnostic coil 5, the switch 3 and the return wiring 48. There are two wires, and as is clear from the figure, the operation is not affected even if the connection is reversed. Therefore, not only the number of wires is reduced, but also the wiring work is facilitated.

Next, the operation will be described. When the switch 43 is tilted to the side of the resistor 42, the current passing through the resistor 42 flows through the diagnostic coil 5 and the switch 3. When the switch 3 is on, the current value is made sufficiently small so that the switch 3 does not operate due to the current flowing through the diagnostic coil. The resistance value of the resistor 42 is obtained from this condition. This state is a non-diagnosis state and the sensor switch is in a normal state. A current is flowing in the resistor 42, and the voltage of 44 is lower than the power supply voltage. At this time, when the sensor switch works and the switch 3 is turned off, the resistor 42
No current flows through. Therefore, the voltage of 44 becomes equal to the power supply voltage, and it can be determined that the switch 3 is turned off.

When the switch 43 is tilted to the side of the resistor 45,
A current that has passed through the resistor 45 flows through the diagnostic coil 5 and the switch 3. The value of the resistor 45 is set so that when the switch 3 is turned on, a sufficient current flows through the diagnostic coil 5 to operate the switch 3. Tilting the switch 43 toward the resistor 45 means starting diagnosis. Diagnosis is performed when the sensor switch is normal. That is, the switch 3 is in the on state.

Therefore, sufficient current flows through the diagnostic coil 5 to operate the switch 3. Then, the switch 3 is turned off and the current becomes zero. Since the current of the diagnostic coil 5 also becomes zero, the switch 3 is turned on again. That is, the switch 3 is temporarily turned off. The voltage of 46 also changes with the on / off of the above current. In the non-diagnosis state, no current flows, so the voltage is high. When the switch 43 is tilted to the resistance 45 side, a current flows and the voltage drops. Here, when the switch 3 is turned off, the voltage rises, and when the switch 3 is turned on again, the voltage drops. This temporary increase in voltage of 46 is caused by the flip-flop 23.
It is stored as in the third embodiment.

If the switch 3 does not operate due to a failure, the voltage of 46 simply drops to a low voltage at the start of diagnosis and does not increase temporarily. This makes it possible to diagnose a failure.

When the switch 3 operates, if the switch 43 continues to be tilted to the resistance 45 side, oscillation occurs. Therefore, when the switch 3 operates, the switch 43 is quickly returned to the resistance 42 side. Therefore, it is necessary to put it in a non-diagnostic state.

Here, the switch 43 may be a semiconductor switch. Further, in this example, the power source 41 is a common power source, but the resistors 42 and 45 may supply different power sources.

As a modification of the fifth embodiment, the diagnostic / non-diagnostic switching circuit may be configured as shown in FIG. In FIG. 7, the switch 43 is a changeover switch, and the resistors 42 and 45 are in parallel. On the other hand, in FIG. 8, the switch 43 operates so as to short-circuit the resistor 42. The resistor 42 and the resistor 45 are connected in series. The values of the resistors 42 and 45 are the same as those in FIG. 7. When the switch 43 is off, it is during non-diagnosis, and when the switch 43 is on, it is during diagnosis. When the switch 43 is off, the current is limited by the resistor 42, and the switch 3 does not operate depending on the diagnostic coil. When the switch 43 is on, the resistor 42 is short-circuited and a large current flows only by the resistor 45, so that the switch 3 is operated by the diagnostic coil 5. Other operations are the same as those in FIG. 7. The ON / OFF of the switch 3 can be detected by the voltage of 44 or 46 when no diagnosis is made. At the time of diagnosis, the voltage of 46 can be detected.

In both cases of FIG. 7 and FIG.
The position of the resistor 43 can be on the ground side instead of the power source side. In FIG. 8, it is also possible to place one of the resistor 42 (and hence the switch 43) and the resistor 45 on the power supply side and the other on the ground side.

In this embodiment, the value of the current flowing through the diagnostic coil 5 is created by the resistance values of the resistors 42 and 45. The current value may be created by other methods. Also, the on / off of the current accompanying the on / off of the switch 3
The off state is detected by the voltage drop across the resistors 42 and 45. Other methods may be used to detect the on / off of the current. For example, a photocoupler is used instead of the resistor 45, the light emitting diode of the photocoupler is connected to the power supply and the switch 43, and a specified current value is obtained by the voltage of the power supply. On / off may be detected.

This fifth embodiment cannot be applied to the usage of the sensor switch unless the switch 3 is always on. That is, when the switch 3 is normally off, current cannot be passed through the diagnostic coil for diagnosis. Therefore, the switch 3 can only be diagnosed in the direction from ON to OFF.

However, in many cases, this restriction does not cause any obstacle in practical use. Generally, in detecting an abnormality, a fail-safe design is performed. That is, the sensor switch is designed to be in an abnormal state even when the power is turned off or the wiring is broken. For this purpose, the contact of the sensor switch is selected so that it is always on when it is on. Example 5 is consistent with this. Further, at this time, the failure that the contact of the switch 3 is not turned on when it should be turned on is in the same state as the occurrence of the abnormality, and therefore can be detected without performing the diagnosis according to the present invention.

[0073]

Sixth Embodiment A fifth embodiment is a switch 3 of a sensor switch.
However, it cannot be implemented unless it is always on. Also in the first embodiment and the like, it is desirable that the switch 3 is always on from the standpoint of fail-safe design.
In general, it is possible to select a sensor switch in which the switch 3 is normally on.

However, in the magnetic proximity switch shown in the first embodiment, the switch 3 is turned on at the time of proximity due to the structure.
The switch 3 is turned off during non-proximity, and the reverse operation cannot be performed. Therefore, the switch 3 cannot be turned on at all times when it is used in the non-proximity state at all times and in the proximity state at abnormal times.

The sixth embodiment solves such a problem.
The configuration is shown in FIG. Reference numeral 1 denotes a proximity switch, and the reed switch 3, the lead wire 4, and the diagnostic coil 5 are the same as those of the proximity switch 1 of the first embodiment. 8 is a permanent magnet. The object 2 whose proximity is to be detected is the same as that in the first embodiment and is not shown. When the object 2 approaches, the permanent magnet 8 is set so that the magnetic flux of the permanent magnet 6 contained in the object 2 and the magnetic flux of the permanent magnet 8 cancel each other at the lead wire 4.

Therefore, when the object 2 approaches, the lead wire 4 is not excited and the switch 3 is turned off. When the object 2 is out of proximity, the lead wire 4 is excited by the permanent magnet 8 and the switch 3 is turned on.

In this example, the permanent magnet 8 is used, but the same applies if a coil that is energized is used instead of the permanent magnet 8, and a coil that is energized can be used.

Further, when the energized coil is used instead of the permanent magnet 8, this coil can also be used as the diagnostic coil 5. At this time, the configuration of the proximity switch is the same as that of the first embodiment shown in FIG. In Example 1,
The diagnostic coil 5 is not energized during non-diagnosis, and the diagnostic coil 5 is energized during diagnosis. In this embodiment, conversely, the diagnostic coil may be energized during non-diagnosis and the diagnostic coil may be de-energized during diagnosis. Others are the same as in the first embodiment.

In the case of using the permanent magnet 8 described above, in the case of using a coil which is energized in place of the permanent magnet 8 and also when the diagnostic coil 5 also serves as this coil, the second embodiment is used. Or can be used in combination with Example 5.

The present invention can also be applied to sensor switches other than magnetic proximity switches.

[0081]

As described above, according to the present invention,
The failure diagnosis of the sensor switch can be performed remotely, easily and inexpensively without actually operating the sensor switch. Moreover, when individual wiring is carried out, the wiring can be carried out inexpensively and easily.

[Brief description of drawings]

FIG. 1 shows a configuration of a proximity switch according to the present invention.

FIG. 2 shows another configuration of the proximity switch according to the present invention.

FIG. 3 shows a configuration of another embodiment of the present invention.

FIG. 4 shows the configuration of another embodiment of the present invention.

FIG. 5 shows a configuration of another embodiment of the present invention.

FIG. 6 shows the configuration of another embodiment of the present invention.

FIG. 7 shows details of the embodiment of FIG.

FIG. 8 shows another detailed example of the embodiment of FIG.

FIG. 9 shows a configuration of still another embodiment of the present invention.

[Explanation of symbols]

 1 Proximity switch 2 Object whose proximity is detected 3 Reed switch 4 Lead wire 5 Diagnostic coil 6 Permanent magnet 11 Sensor 12 Switch 13 Amplifier 14 Coil 15 Contact with magnetic piece 16 Switch 17, 18 Simulated input

Claims (4)

[Claims] 1. A sensor switch having a contact that opens and closes, comprising: a diagnostic coil; and a magnetic piece that is activated by being energized by energizing the diagnostic coil. The contact of the sensor switch depends on the operation of the magnetic piece. The sensor switch with a diagnostic function is characterized in that the malfunction of the sensor switch is diagnosed by energizing the diagnostic coil. 2. When the contact of the sensor switch operates by energizing the diagnostic coil, the operation is stored so that failure diagnosis can be performed even if the operation of the contact of the sensor switch is temporary. The sensor switch with a diagnostic function according to claim 1, wherein 3. When the contact of the sensor switch is normally on in a normal use state of the sensor switch, the sensor switch and the diagnostic coil are connected in series, and the value of the current flowing in the series circuit is When diagnosing, the value that the contact of the sensor switch does not operate due to the current flowing through the diagnostic coil is set, and during diagnosis, the value that causes the contact of the sensor switch to operate due to the current flowing through the diagnosing coil is used to perform 2-wire wiring. The sensor switch with a diagnostic function according to claim 2. 4. A permanent magnet or an energized coil is added so that the contact of the sensor switch is normally turned on in a normal use state of the sensor switch. Sensor switch with diagnostic function.