JP2020187581A - Emergency stop circuit - Google Patents

Abstract

To provide a circuit device capable of identifying states of switches causing all emergency stop factors without increasing a parallel number when a mechanism causing three or more emergency stop factors is in an emergency stop side state in order to check states of switches arranged in series in a production automatic machine.SOLUTION: An emergency stop circuit for stopping operation of a driving source comprises an emergency stop mechanism 104 including two or more contact, first power supply means 202 electrically conducted to a first contact 104-A of the emergency stop mechanism, second power supply means 301 electrically conducted to a second contact of the emergency stop mechanism, and switching means for performing passive operation by electric conduction to the second power supply means 301. The first contact is connected in series to the switching means. The second power supply means 301 is a low voltage on which the driving source does not operate.SELECTED DRAWING: Figure 3

Description

The present invention relates to an emergency stop circuit in a production automatic machine or the like used in a factory or the like.

In production automatic machines used in factories, etc., in order to make an emergency stop of the machine for the purpose of avoiding danger such as personal injury when the machine falls into an abnormality or enters the safety fence of the machine for maintenance reasons. , Emergency stop circuits that work with emergency stop switches, safety area sensors, door switches, etc. are widely used. This emergency stop circuit cuts off the power supply of the drive source such as a motor that operates under the control of an automatic machine by operating the emergency stop switch, etc., thereby making the drive source inoperable and realizing the emergency stop function. There is.

However, mechanical contact relays, magnetic contactors, etc., which are often used to shut off the power system in an emergency stop circuit, are in short mode because the contacts are welded due to factors such as inrush current generated during normal operation and heat generation due to applied current. If it breaks down, its blocking function may be impaired.

As a solution to this problem, as shown in Patent Document 1, there is a method in which an emergency stop switch is provided with a plurality of contacts, and a plurality of magnetic contactors that operate independently depending on the open / closed state of each contact are connected. The plurality of magnetic contactors are connected in series between the drive source and the power supply source thereof, so that even if one of the plurality of magnetic contactors fails in the short mode, the other electromagnetic contactor A method has been proposed in which a device can be used to cut off the circuit and improve the reliability of the emergency stop circuit.

Furthermore, when multiple emergency stop switches are installed, one contact of the emergency stop switch is connected in series (hereinafter referred to as line A) on the coil side of the magnetic contactor installed between the drive source and the power supply source. The other contact of the connection / emergency stop switch is also arranged in series in the same manner, and the contacts are arranged in the reverse order of the line A so that the direction in which the current flows is opposite to that of the line A (hereinafter referred to as line B). ). Both line A and line B are provided with power supply detecting means such as a photocoupler and a relay on the downstream side of the contact in the direction of current flow, and a plurality of emergency stops arranged in series by monitoring the output of the power supply detecting means. It is possible to determine the open / closed status of each switch.

Japanese Unexamined Patent Publication No. 11-11274

Depending on the production automatic machine, a plurality of mechanisms that cause an emergency stop such as an emergency stop switch, a safety area sensor, and a door switch are often installed. However, in the prior art, in order to confirm the status of the switches arranged in series, when three or more mechanisms that cause an emergency stop are in the state of the emergency stop side, the states of all the switches that cause the emergency stop are specified. Can't. In order to identify the state of all the mechanisms that cause an emergency stop, the number of parallels is increased, so that the cost of the emergency stop circuit increases.

In view of the above, the emergency stop circuit according to the present invention is
An emergency stop circuit that stops the operation of the drive source.
An emergency stop mechanism with two or more contacts,
A first power supply means for energizing the first contact of the emergency stop mechanism, and
A second power supply means for energizing the second contact of the emergency stop mechanism, and
A switching means that is passive by energizing the second power supply means is provided.
The first contact and the switching means are connected in series,
The second power supply means is characterized in that the voltage is so low that the drive source does not operate.

According to the present invention, it is possible to easily identify the states of all the mechanisms that cause an emergency stop, and the switching means can be configured by a semiconductor such as a transistor, so that an emergency stop with high reliability is possible. The circuit can be provided at a lower cost.

Schematic diagram of the production automatic machine. Block diagram of the control unit of the production automatic machine. Circuit diagram of the emergency stop circuit. Flow chart of failure detection processing when the emergency stop circuit is energized. Flowchart of failure detection processing when the emergency stop circuit is interrupted. Other schematics of the emergency stop circuit.

(Example 1)
FIG. 1 is a schematic view of a production automatic machine equipped with the emergency stop circuit of the present invention, and is a bird's-eye view from the top surface direction.

In the production automatic machine, for example, a drive source 102 such as an electric motor or an air cylinder is arranged in the area 101, and the production operation is automatically performed according to a program by a user operation or the like. The drive source 102 arranged in the area 101 may operate at a high output that may injure the human body, or may operate at a speed that cannot be safely avoided by humans. In order to prevent danger to people around the production automatic machine, it is covered with a sufficiently strong safety fence 103 made of a plate, wire mesh, or the like so that the area 101 cannot be easily invaded.

However, there are cases where it is desired to stop the production automatic machine in an emergency due to a malfunction of the production automatic machine itself, and an emergency stop switch 104 is arranged in the vicinity of the production automatic machine as the stopping means. In addition, there are many situations in which it is unavoidable to invade the area 101, such as when it is necessary to correct the above-mentioned problems, when parts are supplied to the production automatic machine, or when parts are discharged from the production automatic machine. Exists.

At that time, in order for a person to invade the area 101, the safety fence 103 is provided with doors 111 to 116, and the opening and closing of the doors 111 to 116 is detected by the door switches 121 to 126 installed on each door. To do.

In addition, an area sensor may be placed at the frontage where parts are frequently supplied and discharged. The area sensor is composed of a pair of an area sensor 127 on the light emitting side and an area sensor 128 on the light receiving side, and the light is projected. It detects whether or not the optical axis 129 connecting the area sensor 127 on the side and the area sensor 128 on the light receiving side is blocked, and is mounted instead of the door. The area sensor has a contact switch on the light receiving side that operates depending on the light blocking effect of the optical axis 129. The emergency stop switch 104, the door switches 121 to 126, and the area sensors 127 and 128 are all connected to the emergency stop circuit mounted on the production automatic machine.

FIG. 2 is a block diagram showing the relationship between the control system of the production automatic machine, the power supply of the drive source 102, and the emergency stop circuit.

In the production automatic machine of the present embodiment, the operation / stop of the drive source 102, the pressed state of the emergency stop switch 104, the open / closed state of the door switches 111 to 116, and the operation / stop of the drive source 102 by the control unit 201 mainly composed of the microcomputer, PLC, PC, etc. It monitors the light-shielding state of the area sensors 127 and 128.

The power supply required to operate the drive source 102 is supplied from the power supply 202, and is performed via the relay 204 included in the emergency stop circuit 203 and the switching element 205 connected in series with the relay 204.

The relay 204 is independent of the control unit 201 depending on the state of each emergency stop switch 104, door switches 121 to 126, and emergency stop mechanisms such as area sensors 127 and 128 (hereinafter, these are collectively referred to as an emergency stop factor). A circuit is built that can be forcibly cut off only by the hardware.

A relay may be used for the switching element 205, but if the switching element 205 is composed of a switching element having a soft start function such as a MOS-FET, the emergency stop state is finally released and the inrush current when power is supplied to the drive source 102, etc. Can be prevented and the circuit life can be extended.

Further, in this embodiment, the relay 204 and the switching element 205 are arranged and separated from the line in which the emergency stop factor is connected in series. However, when the current consumption at the drive source 102 is small, the relay 204 and the switching element are arranged. Instead of providing 205, the output end of the emergency stop factor of the final stage arranged in series may be connected to the drive source 102 to supply power.

FIG. 3 is a circuit diagram showing the characteristic parts of the present invention in detail in the emergency stop circuit 203. Each of the plurality of emergency stop factors connected to the emergency stop circuit 203 has two or more switches, and the two switches are connected to the emergency stop circuit 203 and are connected in series according to the rules described below.

The emergency stop circuit 203 operates by supplying power from a power supply 202 that outputs a voltage of about 24 V, which is a voltage capable of operating the drive source 102. In the present embodiment, a low-voltage power supply 301 that outputs a voltage of about 5 V is generated in the emergency stop circuit 203 by using a circuit such as a DC / DC converter or a three-terminal regulator, and is supplied to each part.

Here, the minimum operating voltage of the relay is approximately 40 to 50% of the rated voltage, and the low voltage power supply 301 has a voltage lower than the minimum operating voltage of the relay 204. By setting the relationship between the voltage ratio of the power supply 202 and the low voltage power supply 301, the control side of the relay 204 does not operate directly at the voltage of the low voltage power supply 301, and the control side operates at the voltage of the power supply 202. This is a feature of the present invention.

The low voltage power supply 301 may be generated outside the emergency stop circuit 203 and supplied to the emergency stop circuit 203.

An overvoltage protection circuit that monitors the output voltage of the low voltage power supply 301 is connected to the output terminal of the low voltage power supply 301, and when the output voltage of the low voltage power supply 301 exceeds the minimum operating voltage of the relay 204, The output of the low-voltage power supply 301 is stopped, and the output of the power supply 202 is also stopped at the same time.

First, one of the two contacts of the emergency stop switch 104, which is the most upstream of the circuits connected in series among the plurality of emergency stop factors, via the switching element 302 switched by the control of the control unit 201. A power supply 202 as a power supply source is connected to 104-A.

As an example, the switching element 302 uses an element that can be switched by a control unit 201 such as a transistor. Further, the low voltage power supply 301 as the supply source is the other contact 104-of the two emergency stop switches 104 via the switching element 303 which is switched by the control of the control unit 201 with the low voltage power supply 301 as the supply source. Connected to B. The switching element 303 is also composed of the equivalent of the switching element 302.

The power supply line connected via the contact 104-A of the emergency stop switch 104 is connected to the switching element 304. In the switching element 304, the voltage of the supply line connected via the contact 104-A of the emergency stop switch 104 described above is larger than the minimum operating voltage of the relay 204, and the voltage of the switching element 304 is via the switch of the contact 104-B of the emergency stop switch. It is connected so that the switch is turned on by inputting both the voltages of the power supply lines connected to the above. As the switching element 304, a transistor or the like is used like the switching element 302.

Further, when the switching element 304 is composed of transistors, the diode 307 is connected in parallel to the base and the output end, and the anode end of the diode 307 is connected to the supply line side connected via the switch of the contact 104-B of the emergency stop switch. Is connected, and the cathode end of the diode 307 is connected to the output end side of the switching element 304. With this configuration, when both the contact 104-A side of the emergency stop switch 104 and the contact 104-B side of the emergency stop switch 104 are on at the output end of the switching element 304, the power supply 202 is used. When the generated 24V is output and only the contact 104-B side of the emergency stop switch 104 is on, the 5V generated by the low voltage power supply 301 is output. No voltage is output to the output end of the switching element 304 when only the contact 104-A side of the emergency stop switch 104 is on or both are off. According to this configuration, as will be described later, it is possible to detect that each emergency stop factor is turned on by a change in the voltage at the output end of the switching element 304.

Further, the contact 104-A of the emergency stop switch is provided by the voltage monitoring means 305 and 306 (contact monitoring means) for monitoring the voltage of the power supply line connected via the contacts 104-A and 104-B of the emergency stop switch 104, respectively. The energization state of 104-B is monitored, and the control unit 201 is notified. The voltage monitoring means 305 and 306 do not operate the relay 204 even if the interface unit of the control unit 201 fails or is set to the output port due to a software setting error. It is composed of a passive circuit of impedance and a low voltage power supply 301 for the output voltage of the interface unit of the control unit 201 after being composed of transistors, etc., and the voltage monitoring means 305 is equal to or higher than the minimum operating voltage of the relay 204. The voltage monitoring means 306 sets the voltage at which the output voltage of the low voltage power supply 301 or higher can be detected.

The connection configuration of the two contacts 104-A and 104-B, the switching elements 303 and 304, and the voltage monitoring means 305 and 306 excluding the switching element 302 described above is set as one set, and the door switches 121 to 126 and the area sensor are used. The light receiving side 128 of is also connected in series in the same manner.

In FIG. 3, only the emergency stop switch 104 to the door switches 121 and 122 and the light receiving side 128 of the area sensor in the final stage are shown, and the remaining door switches 123 to 126 are omitted. The switching elements 313 and 373 have the same role as the switching element 303 and are the same components. However, it does not necessarily have to be the same component.

Similarly, the switching elements 314 and 374 are the same components as the switching element 304 in the same role, and the voltage monitoring means 315 and 375 are the same components in the same role as the voltage monitoring means 305, respectively, and the voltage monitoring means 316 and 376. Is a component having the same role as the voltage monitoring means 306, and these sets are combined with the contact 121-A of the switching element 304 and the door switch 121, the contact 122-A of the switching element 314 and the door switch 122, and the switching element 324. The door switch 123 is connected in series in the form of contacts 123-A ....

Then, after connecting all the emergency stop factors in series, in this example, the switching element 374 having the same role as the switching element 304 in the circuit group of the area sensor 128 is connected to the coil side of the relay 204. As described with reference to FIG. 2, a switching element 205 is connected to the switch side of the relay 204.

The on / off control of the switching element 205 operates by receiving the output of the logical product circuit 308 of the voltage applied to the coil side of the relay 204 and the control signal of the control unit 201. A voltage monitoring means 309 is connected to the drive source 102 side (switching element 205 side) on the switch side of the relay 204. The voltage monitoring means 310 is also connected to the drive source 102 side of the switching element 205. The voltage monitoring means 309 and 310 are the same components as the voltage monitoring means 305 and the like described above.

Although the switching elements 302 to 304, 313, 314 ... 374 have the same components, they are not limited to the same components as long as they have the same function. With this circuit configuration, the I / O of the control unit is all set to the output side and turned on due to a soft bug in the software installed in the control unit 201, a software write failure, or a failure of the main arithmetic unit itself. Even in such a case, it is possible to realize a circuit that makes an emergency stop simply by interrupting one of the emergency stop factors. In this case, in addition to the above-mentioned software malfunction, even if the hardware portion of the emergency stop circuit also has a failure, the emergency stop can be reliably performed. For this reason, since the above-mentioned switching means can be stopped even if there is one failure due to the circuit configuration, it is realized only by a semiconductor such as a transistor without using a relay or the like, which has a low failure rate but is expensive. It becomes possible.

4 and 5 are flowcharts when a failure is detected by using the emergency stop circuit 203 shown in FIG. The failure detection of the emergency stop circuit 203 is performed immediately after the power of the production automatic machine is turned on, between the emergency stop state and the energization of the drive source 102, or when any of the emergency stop factors is turned off. First, the process performed immediately after the power of the production automatic machine is turned on or during the period from the emergency stop state to the energization of the drive source 102 will be described with reference to FIG.

First, after turning off all the switching element 302, the switching element 303, and the switching element group (hereinafter, referred to as the B contact output permission switch group) having the same role as the switching elements 313, 323, 373, etc. Start.

This state is the completion state of the processing executed when any of the emergency stop factors described later is turned off. After that, all the B contact output permission switches are turned on (S401). If the emergency stop factor is on, 5V, which is the output of the low voltage power supply 301, is output to the output terminals of the switching element 304 and the switching elements 314, 324 ... 374 (B contact passive switching element group). It will be in a state of being. This output voltage is monitored by the control unit 201 using voltage monitoring means 306, voltage monitoring means 316, 326, ... 376 and other voltage monitoring means (hereinafter, referred to as B contact output monitoring group) having an equivalent role. This waits for all emergency stop factors to be turned on (S402).

After confirming that all the emergency stop factors are on, the switching means is turned on while inspecting whether there is a short mode failure from the upstream part of the series circuit, so the B contact output permission switch Turn off all groups again (S403).

Next, the voltage monitoring means 305 is monitored for no voltage (S404), and if there is a voltage, the switching element 302 is determined to have a short mode failure (N in S404). If there is no voltage, it is determined that the switching element 302 is not a short mode failure (Y in S404), and the switching element 302 is turned on (S405).

After that, it is confirmed that there is no voltage in the voltage monitoring means 306 (S406), and if there is a voltage, the switching element 304 determines that the short mode failure (N in S406). If there is no voltage in the voltage monitoring means 306 (Y in S406), it is confirmed that the voltage monitoring means 305 has a voltage (S407), and if the state of no voltage continues for a certain period of time or longer (N in S407), switching is performed. The element 303 is turned on (S471).

The voltage of the voltage monitoring means 306 is monitored when there is no voltage in the voltage monitoring means 305 (S472), and if there is a voltage, the emergency stop switch 104 is determined to be in a half-pressed state or a disconnection failure (N in S472). .. If there is no voltage, the emergency stop switch 104 is pressed, the failure detection process is stopped on the assumption that the emergency stop state is reached, and the process proceeds to the emergency stop process described later (Y in S472).

When it can be confirmed in S407 that the voltage monitoring means 305 has a voltage (Y in S407), the switching element 303 is turned on (S408). After that, it is confirmed whether the voltage monitoring means 315 has a voltage, and if there is no voltage (N in S409), it is confirmed that there is no voltage in the voltage monitoring means 306 upstream of the contact to be confirmed in this step (S473). If there is a voltage, it is determined that the contact 121-A of the door switch 121 is broken (N in S473). If there is no voltage, it is determined that the emergency stop has occurred due to the emergency stop factor, the process is stopped assuming that the emergency stop state has been reached again, and the process proceeds to the emergency stop process described later (Y in S473).

At this time, if the cause of the emergency stop is a sensor such as a light curtain, workability is taken into consideration, and the time is equal to or longer than the time required to supply parts or work to a normal production automatic machine without immediately shifting to the emergency stop process. Is set, and when the set time elapses or more, the process shifts to the emergency stop (S474), so that it is possible to prevent the emergency stop from being frequently applied when working with the production automatic machine. Even if this interruption time is long, no power is applied to the final stage of the emergency stop circuit, so there is no problem in safety.

If there is a voltage in the voltage monitoring means 315 in S409 (Y in S409), then it is confirmed that there is no voltage in the voltage monitoring means 316, and if there is a voltage, the switching element 314 is determined to have a short mode failure (S410). N). If there is no voltage, the switching element 313 is turned on (S411).

After that, the flow described in the sequence processing of S409 to S411 is repeatedly executed until the relay 204 of the final stage is reached. At that time, the voltage monitoring means 315 of S409 is the voltage monitoring means 375 ..., the voltage monitoring means 316 of S410 is the voltage monitoring means 376 ..., The switching element 313 of S411 is the switching element 373 ..., The voltage of S473. The monitoring means 306 is replaced with a circuit group for each emergency stop factor arranged in series having the same role as the voltage monitoring means 316 ...

By executing this process, even if the sequence is advanced until the coil of the relay 204 is energized, the voltage monitoring means 315 of S409 is the voltage monitoring means 309, the voltage monitoring means 316 of S410 is the voltage monitoring means 310, and the switching element 313 of S411 is the switching element 205. , S473, the voltage monitoring means 306 is replaced with the voltage monitoring means 376 for confirming the output state of the contacts 128-B of the area sensor 128 for execution processing. By executing this process to the end, it can be confirmed that there is no failure in the emergency stop circuit unless a failure is detected.

FIG. 5 is a flowchart of processing executed when an emergency stop is caused by any of the emergency stop factors. This process is based on the premise that all the switching elements are in the ON state and the power is supplied to the drive source 102 after the flowchart shown in FIG. 4 is executed.

The emergency stop state due to the emergency stop factor means that the voltage monitoring means 305, the voltage monitoring means 315, ... 375, and the like, which have the same role as the voltage monitoring means (hereinafter referred to as the A contact output monitoring group), and B All of the contact output monitoring group is monitored, and if there is no voltage in any of them, the emergency stop factor causes an emergency stop, and this process is started (S501).

After that, the other voltage monitoring means of the emergency stop factor connected to the voltage monitoring means that has detected the state of no voltage also detects whether or not there is no voltage. For example, if the emergency stop switch 104 is pressed and the voltage monitoring means 306 first detects that there is no voltage, it is confirmed that the other voltage monitoring means 305 also has no voltage (S502).

When the voltage monitoring means show different states, it is determined that one of the two contacts of the emergency stop factor has failed in the short mode (N in S502). For example, when the voltage monitoring means 305 has a voltage and the voltage monitoring means 306 has no voltage, it can be determined that the contact 104-A has a short mode failure. If both voltage monitoring means show the same state (both are off), it is determined that there is no failure (Y in S502).

When S501 and S502 are confirmed for all the voltage monitoring means, the outputs of all the switching elements 302, the B contact output permission switch group, and the switching element 205 are turned off (S503). Then make sure that all voltage monitoring means are free of voltage. It is determined that the voltage monitoring means having a voltage is a failure (N in S504), and if there is no voltage in all the voltage monitoring means, it is confirmed that there is no failure in all the voltage monitoring means (Y in S504). After that, the process proceeds to the process shown in FIG.

(Example 2)
FIG. 6 shows a circuit diagram of an emergency stop circuit of the production automatic machine according to the second embodiment of the present invention. Since many configurations are common to the first embodiment, the description thereof will be omitted, and only the different parts will be described below.

The roles of the switching elements, the voltage monitoring means, and the like in this embodiment are basically the same as those in the first embodiment. Further, it is specifically shown that each switching element and the voltage monitoring means are composed of transistors. In particular, by connecting transistors in two stages as switching elements 304, 314 and the like, a low current can be obtained. It enables switching at point B.

Further, in the first embodiment, the voltage monitoring means 306 and the like are provided on the output end side of the switching element 304, but in this embodiment, they are provided on the base side of the switching element 304.

According to the present invention, in any state including a soft bug of the control unit 201, an emergency stop circuit that can surely cut off the power supply of the drive source 102 when one failure of the emergency stop circuit occurs, and the failure is detected. It is possible to provide a control method of a highly reliable emergency stop circuit.

101 Area 102 Drive source 103 Safety fence 104 Emergency stop switch 111-116 Door 121-126 Door switch 127, 128 Area sensor 201 Control unit 202 Power supply 203 Emergency stop circuit 204 Relay 205 Switching element 301 Low voltage power supply 302 Switching element 303, 313・ ・, 373 B contact output permission switch group 304, 314 ・ ・ 374 B contact passive switching element group 305, 315 ・ ・ 375 A contact output monitoring group 306, 316 ・ ・ 376 B contact output monitoring group

Claims (4)

An emergency stop circuit that stops the operation of the drive source.
An emergency stop mechanism with two or more contacts,
A first power supply means for energizing the first contact of the emergency stop mechanism, and
A second power supply means for energizing the second contact of the emergency stop mechanism, and
A switching means that is passive by energizing the second power supply means is provided.
The first contact and the switching means are connected in series,
The second power supply means is an emergency stop circuit having a low voltage so that the drive source does not operate. The emergency stop mechanism is energized by monitoring the output of the second contact with the second contact monitoring means in a state where the energization from the first power supply means is turned off and the energization from the second power supply means is turned on. The emergency stop circuit according to claim 1, wherein the state is confirmed. An emergency stop circuit in which a plurality of the emergency stop mechanisms are connected in series.
A first contact monitoring means for monitoring the output of the first contact is provided.
The second power supply means is turned on in the order in which they are connected in series, and the second power supply means in another emergency stop mechanism connected downstream of the second contact, which is energized by the second power supply means. The emergency stop circuit according to claim 2, wherein a failure of each of the emergency stop mechanisms is detected by monitoring the outputs of one contact and the second contact. When the output of the first contact and the second contact of the emergency stop mechanism connected to the upstream of the emergency stop mechanism during failure detection and the failure has already been detected is monitored and the output is turned off, The emergency stop circuit according to claim 3, further comprising suspending failure detection until the output is turned on or a certain period of time or more has elapsed.

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