JP2015041544A - Non-contact safety switch and machine control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact safety switch and machine control system having a function for detecting whether or not the switch normally performs conduction and non-conduction.SOLUTION: A safety switch 1 includes: a reed switch 11; a first terminal 13; a second terminal 14; two coils 12A, 12B (equivalent to a magnet field generation part) which are wound around outer peripheries of both ends of the reed switch 11 so as to be separated from each other and are independent of each other; third terminals 15a, 15b for making current flow in the coil 12A; and third terminals 16a, 16b for making current flow in the coil 12B. A machine control system performs: OFF check in which failure detection is determined by determining whether or not the read switch 11 is turned OFF, when making a magnetic field act in a direction to forcibly separate contact points of the reed switch 11 by making current flow in the coils 12A, 12B; and ON check in which failure detection is determined by determining whether or not the read switch 11 is turned ON, when making the magnetic field act in a direction to forcibly connect the contact points of the reed switch 11.

Description

  The present invention relates to a non-contact safety switch used for machine equipment and the like, and a machine control system including the non-contact safety switch.

  Conventionally, there exists a safety switch like patent document 1. FIG. Since this switch relates to safety, it is important whether conduction (ON) or non-conduction (OFF) is normally performed.

JP 2004-119192 A

  However, there was no function to detect whether the safety switch is normally conducting or not conducting.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a non-contact safety switch and a machine control system having a function of detecting whether or not normal conduction or non-conduction is performed.

  In order to achieve the above object, the invention according to claim 1 is characterized in that the first terminal, the second terminal, and the magnetic field due to the approach of the door are connected between the first terminal and the second terminal. A reed switch for non-conduction, a magnetic field generating unit that applies a magnetic field to the reed switch, and a magnetic field applied to the reed switch by driving the magnetic field generating unit regardless of the approach of the door, A non-contact safety switch, comprising: a third terminal for inputting a control signal for forcibly conducting or non-conducting between the terminal and the second terminal.

Here, the “terminal” may be any terminal that inputs and outputs a signal, and may be a wiring that is drawn out from the inside of the non-contact safety switch in addition to what is commonly called a terminal.
According to said structure, by giving a control signal to a 3rd terminal, regardless of the approach of a door, between 1st terminal and 2nd terminal is forcedly made into conduction or non-conduction. It is possible to detect whether the non-contact safety switch is normally conducting or non-conducting.

  The invention according to claim 2 is the non-contact safety switch according to claim 1, wherein the magnetic field generator is two coils provided separately on the outer periphery of both ends of the reed switch. One coil is composed of one continuous coil winding.

  According to the above configuration, the third terminal can be configured with a small number, and a safety switch having a relatively simple configuration is configured.

  The invention according to claim 3 is the non-contact safety switch according to claim 1, wherein the magnetic field generator is two coils provided separately on the outer periphery of both ends of the reed switch. Each of the two coils is separated and independent.

  According to the above configuration, the OFF check and the ON check can be performed by switching the direction of the current flowing through the coil.

  The invention according to claim 4 is a machine control system for controlling a machine, wherein the non-contact safety switch according to any one of claims 1 to 3, the first terminal, and the second terminal. And when electrically connected to the third terminal and receiving conduction or non-conduction between the first terminal and the second terminal, the control signal is output to the third terminal, And a control unit that permits the operation of the machine if conduction or non-conduction between the first terminal and the second terminal satisfies a predetermined condition.

  According to the above configuration, it is possible to detect whether the non-contact safety switch is normally conducting or non-conducting and to control the operation of the machine according to the detection result, so that a machine control system with improved safety is constructed. Is done.

  According to the present invention, by giving a control signal to the third terminal, the first terminal and the second terminal are forcibly made conductive or non-conductive regardless of the approach of the door, It is possible to detect whether the non-contact safety switch is normally conductive or non-conductive.

The block diagram which shows the example of application of the non-contact safety switch in embodiment of this invention. The block diagram of the machine control system in embodiment of this invention to which the non-contact safety switch of embodiment of this invention was applied. The flowchart which shows the failure detection process in the machine control system in embodiment of this invention. The block diagram of the modification of a machine control system. The block diagram of the other modification of a machine control system.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an application example of a non-contact safety switch (hereinafter abbreviated as a safety switch) in an embodiment of the present invention, which is applied to an entrance / exit 200 of a safety fence 4 surrounding a machine 3 such as an industrial robot. An example is shown. In the place where the machine 3 is installed, the machine 3 is surrounded by the safety fence 4 and the door 5 of the entrance / exit 200 is opened in order to prevent an operator (not shown) from getting caught in the machine 3 and being injured. In this state, the machine 3 is designed not to operate in a state where an operator can freely enter and exit.

  Specifically, the safety fence 4 surrounds the room 100, and the machine 3 is installed in the room 100. The safety fence 4 is provided with an entrance / exit 200, and an operator and a transported object can enter / exit between the outside and the room 100 through the entrance / exit 200. The safety fence 4 is provided with a door 5 for closing the entrance / exit 200. The door 5 can freely move in the lateral direction Z.

  A safety switch 1 is provided near the end 4 a of the safety fence 4. An operation member 2 realized by a magnet is attached to the end 5 a of the door 5. When the door 5 is opened, the safety switch 1 is in a non-conductive state (OFF state), and the control unit 6 does not permit the operation of the machine 3 when receiving the non-conductive state. Further, when the door 5 is closed, the safety switch 1 becomes conductive (ON state) in response to the approach of the operation member 2, and the control unit 6 permits the operation of the machine 3 when receiving the conductive state.

  FIG. 2 is a configuration diagram of the machine control system in the embodiment of the present invention to which the safety switch of the embodiment of the present invention is applied. The machine control system 10 includes a safety switch 1, a control unit 6 that performs signal processing from the safety switch 1, and a machine control unit 8 that controls operation / stop of the machine 3. The safety switch 1 includes a reed switch 11, a first terminal 13, a second terminal 14, and two coils 12 </ b> A and 12 </ b> B (separated to the magnetic field generation unit) that are separately applied to both ends of the reed switch 11. And third terminals 15a and 15b for supplying current to the coil 12A and third terminals 16a and 16b for supplying current to the coil 12B.

  The reed switch 11 is a general reed switch having a structure in which two ferromagnetic leads are sealed in an airtight container such as a glass tube together with an inert gas at an appropriate interval. In addition, the coil 12A and the coil 12B are independent from each other, and the coil 12A and the coil 12B are wound in the same direction.

  The first terminal 13, the second terminal 14, and the third terminals 15 a, 15 b, 16 a, and 16 b are electrically connected to the control unit 6.

  Here, when the door 5 is closed, in the safety switch 1, the reed switch 11 receives a magnetic field from the operation member 2 to make the first terminal 13 and the second terminal 14 conductive. When the first terminal 13 is the input side and the second terminal 14 is the output side, a signal indicating that the second terminal 14 is in a conductive state (that is, an ON state) is output. When receiving the signal indicating the ON state, the control unit 6 sends a machine operation permission signal to the machine control unit 8. The machine control unit 8 moves (operates) the machine 3 if there is a machine operation command signal based on the automatic operation program stored in the machine control unit 8 while receiving the machine operation permission signal.

  When the door 5 is open, the safety switch 1 is configured such that the reed switch 11 does not receive the magnetic field from the operation member 2 and is not conducting between the first terminal 13 and the second terminal 14. A signal indicating non-conduction (that is, OFF state) is output from the terminal 14. When receiving the signal indicating the OFF state, the control unit 6 sends a machine operation stop signal to the machine control unit 8. The machine control unit 8 puts the machine 3 into a state of not moving in a state where the machine operation stop signal is received.

  Regardless of the open / closed state of the door 5, the control unit 6 periodically executes a failure detection process of the safety switch 1 (a process for detecting whether the safety switch 1 is normally turned on or off), for example, using a built-in timer. To do. Here, there are two modes of failure detection processing: OFF check and ON check. In the OFF check, when the reed switch 11 is in an ON state, a magnetic field is applied in a direction for forcibly separating the contact point of the reed switch 11, and failure detection is determined by whether or not the reed switch 11 is turned off. Thereby, when the door 5 is opened during the operation of the machine, it can be checked whether the machine 3 can be surely shifted to the safe side where it stops. If the safety switch 1 is turned off, it is normal, and if it is not turned off, contact welding has occurred. In the ON check, when the reed switch 11 is in an OFF state, a magnetic field is applied in a direction in which the contact of the reed switch 11 is forcibly attached, and failure detection is determined by whether or not the reed switch 11 is turned on. If the safety switch 1 is turned on, it is normal, and if it is not turned on, a disconnection has occurred.

  FIG. 3 is a flowchart showing a failure detection process in the machine control system according to the embodiment of the present invention. First, in step S1, the open / closed state of the door 5 is determined. Specifically, if the signal at the second terminal 14 indicates the ON state, the control unit 6 determines that the door 5 is closed, moves to Step 2, and does not indicate the ON state ( That is, if it is in the OFF state), it is determined that the door 5 is open, and the process proceeds to step S5.

  Next, in step S2, a failure check signal determination process is performed. The failure check in step S2 is an OFF check. Specifically, the control unit 6 causes the current to flow in the direction of the third terminal 15a → the third terminal 15b with respect to the coil 12A, and the third terminal 16b → the third terminal 16a with respect to the coil 12B. A current is passed in the direction and the signal at the second terminal 14 is monitored. If a signal indicating an ON state (failure check signal) is not input from the second terminal 14, it is determined as normal and the process proceeds to step S3. Otherwise, the process proceeds to step S4.

  More specifically, since the coil 12A and the coil 12B have the same winding direction, opposite-phase magnetic fields are generated in the coil 12A and the coil 12B. Moreover, the magnetic field generated by the coils 12 </ b> A and 12 </ b> B at this time is set to be larger than the magnetic field generated when the operation member 2 approaches. As a result, when the magnetic field acts on the reed switch 11 in the direction of forcibly separating the contacts and the lead switch 11 is turned off, it is determined that the reed switch 11 is not welded and can be reliably shifted to the safe side.

  In step S3, the control unit 6 outputs a machine operation permission signal to the machine control unit 8 and returns to the original state before performing the failure detection process. Thereby, since the machine control unit 8 continuously receives the machine operation permission signal, if there is a machine operation command signal by the automatic operation program stored in the machine control unit 8 as described above, the machine 3 is moved. (drive). In step S <b> 4, the control unit 6 outputs an error signal to the machine control unit 8. When the machine control unit 8 receives the error signal, the machine control unit 8 stops the movement of the machine 3 and notifies the manager by turning on an alarm lamp, for example.

  In step S5, a failure check signal determination process is performed. The failure check in step S5 is an ON check. Specifically, the control unit 6 causes the current to flow in the direction from the third terminal 15a to the third terminal 15b for the coil 12A, and the direction from the third terminal 16a to the third terminal 16b for the coil 12B. A current is passed through and the signal at the second terminal 14 is monitored. Since the coil 12A and the coil 12B have the same winding direction, a magnetic field having the same phase is generated in the coil 12A and the coil 12B. As a result, a magnetic field is generated in the reed switch 11 in a direction for forcibly attracting the contacts. If a signal indicating a OFF state (failure check signal) is not input from the second terminal 14, it is determined as normal and the process proceeds to step S6. Otherwise, the process proceeds to step S7.

  In step S6, the control unit 6 continues to output a machine operation stop signal to the machine control unit 8, and returns to the original state before performing the failure detection process. Thereby, the machine control unit 8 keeps the machine 3 from moving. In step S <b> 7, the control unit 6 outputs an error signal to the machine control unit 8. When the machine control unit 8 receives the error signal, the machine control unit 8 notifies the administrator by turning on, for example, an alarm lamp while the machine operation is stopped.

  Thus, by performing the failure detection process periodically, whether or not the safety switch 1 is normally turned on and off is detected, and the safety is further improved.

  The failure check of the safety switch 1 requires checking that if the door 5 is opened from the closed state, it can be surely shifted to the safety side where the machine stops. It is indispensable to perform in the state where the door 5 is closed (that is, when the signal from the second terminal 14 indicates the ON state). Therefore, the timing for performing the ON check / OFF check may be performed when the signal from the second terminal 14 is in either the ON state or the OFF state, but at least the signal from the second terminal 14 is It is preferable to do so when the ON state is indicated.

(Other matters)
(1) In the above embodiment, the coil 12A and the coil 12B have the same winding direction, but the winding direction may be opposite. With such a configuration, at the time of OFF check, a current flows in the direction of the third terminal 15a → the third terminal 15b for the coil 12A, and the third terminal 16a → the third terminal for the coil 12B. If a current is passed in the direction of 16b, a reverse-phase magnetic field is generated in the coil 12A and the coil 2B. Therefore, a force for forcibly separating the contacts is generated, and an OFF check can be performed. Further, at the ON check time, a current flows in the direction from the third terminal 15a to the third terminal 15b for the coil 12A, and a current flows in the direction from the third terminal 16b to the third terminal 16a for the coil 12B. If it flows, a magnetic field having the same phase is generated in the coil 12A and the coil 12B, so that a force for forcibly attracting the contact is generated and ON check can be performed.

  (2) In the above embodiment, the coil 12A and the coil 12B are independent from each other. However, as shown in FIG. 4, the coil 12A and the coil 12B are configured by one coil winding in which the coil 12A and the coil 12B are connected. It may be what was done. If the coil 12A and the coil 12B are connected to each other and the winding direction of the coil 12A and the coil 12B is the reverse direction, the third terminal is connected to the coils 12A and 12B during the OFF check. If a current is passed in the direction from 17a to the third terminal 17b, a reverse phase magnetic field is generated in the coil 12A and the coil 12B. Therefore, a force for forcibly separating the contacts is generated, and an OFF check becomes possible. On the other hand, even if the coil 12A and the coil 12B are connected, if the winding direction of the coil 12A and the coil 12B is the same direction, the current can flow in the direction from the third terminal 17a to the third terminal 17b. For example, since a magnetic field having the same phase is generated by the coil 12A and the coil 12B, a force for forcibly attracting the contact is generated, and ON check can be performed. In this way, in the safety switch composed of one coil winding in which the coil 12A and the coil 12B are connected, an OFF check or a check is performed depending on whether the winding direction of the coil 12A and the coil 12B is the same direction or the reverse direction. ON check is possible.

  (3) In the above embodiment and the configuration shown in FIG. 4, the number of the reed switches 11 is one. However, as shown in FIG. 5, a configuration in which two reed switches 11 are provided, and a configuration in which three or more are provided. There may be. In the conventional safety switch with multiple reed switches, there is a problem that occurs when the contact opening / closing identity is confirmed by duplication, that is, when the contact is opened / closed by bringing the magnet closer to determine the failure. When a magnet is brought close (during slow action), only the contact of one reed switch reacts, so there is a problem that the contact opening / closing is lost and the failure is determined. With regard to this problem, the present invention can solve the problem of erroneously determining a failure during the slow action because a failure check is possible regardless of the approach of the magnet even in the configuration in which a plurality of reed switches 11 are provided.

  (4) In the above-described embodiments and the like, the “terminal” may be any terminal that inputs and outputs a signal. In addition to what is called a normal so-called terminal, it may be a wiring drawn out from the inside of the safety switch. .

  (5) In the above-described embodiment and the like, the reed switch 11 is configured with an a contact, but may be configured with a b contact.

  (6) In the above embodiment, the operation member 2 is attached to the door 5 side and the safety switch 1 is attached to the safety fence (wall) 4 side. However, the safety switch 1 is attached to the door 5 side to The operation member 2 may be attached to the side of the fence (wall) 4. In either case, the reed switch 11 is turned on or off between the first terminal and the second terminal by a magnetic field due to the approach of the door 5.

  The present invention is applied to a non-contact safety switch used in machine equipment and the like and a machine control system including the non-contact safety switch.

1: Safety switch 2: Operation member 3: Machine 5: Door 6: Control unit 10: Machine control system 11: Reed switch 12A, 12B: Coil (magnetic field generation unit)
13: 1st terminal 14: 2nd terminal 15a, 15b, 16a, 16b, 17a, 17b: 3rd terminal

Claims (4)

A first terminal;
A second terminal;
A reed switch that establishes conduction or non-conduction between the first terminal and the second terminal by a magnetic field due to the approach of the door;
A magnetic field generator for applying a magnetic field to the reed switch;
Regardless of the approach of the door, the magnetic field generator is driven to cause a magnetic field to act on the reed switch so that the first terminal and the second terminal are forcibly turned on or off. A third terminal for inputting a signal;
Non-contact safety switch characterized by comprising.   The non-contact according to claim 1, wherein the magnetic field generation unit is two coils provided separately on the outer periphery of both ends of the reed switch, and the two coils are configured by a single coil winding connected. Safety switch.   The non-contact safety switch according to claim 1, wherein the magnetic field generation unit is two coils provided separately on the outer periphery of both ends of the reed switch, and the two coils are separated and independent from each other. A machine control system for controlling a machine,
Non-contact safety switch according to any one of claims 1 to 3,
The control signal is electrically connected to the first terminal, the second terminal, and the third terminal and receives the conduction or non-conduction between the first terminal and the second terminal. A control unit that permits the operation of the machine if conduction or non-conduction between the first terminal and the second terminal with respect to the first terminal satisfies a predetermined condition;
A machine control system comprising:

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