JP2007035388A - Power supply device of automatic machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device which supplies electricity to a driving device of an automatic machine with a long service life and high reliability and insures the safety. <P>SOLUTION: The key factor which shortens the life time of a relaying device (a contactor or a relay) is rush current at turn-on and arcing at turn-off, so when turning on and breaking two relaying devices (contactors) for controlling a driving power source, an order is set up and the order is changed at the previously set number of times to prevent a load from concentrating on one contactor and to extend the life time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to power on / off control of a driving device in a control device of an automatic machine.

In a small and medium-sized component processing machine using an automatic machine such as a robot, a worker may sometimes supply or remove a processed component to or from a processing position. At this time, since a part of the worker's body enters the movable range of the automatic machine, the light curtain or the like detects that the worker is approaching the automatic machine and cuts off the drive power to the motor of the automatic machine. By taking measures such as doing this, safety is ensured so that workers are not exposed to danger even if the automatic machine performs unexpected operations such as runaway.
As an example of this safety ensuring means, the power supply device to the motor of the automatic machine is shut off by the emergency stop operation etc., but the emergency stop switch has a plurality of contacts of the same opening / closing phase in parallel. By connecting a plurality of electromagnetic contactors, which are constituted by a multi-circuit switch and opened / closed by opening / closing each of a plurality of contacts of the emergency stop switch, in series with the main circuit power supply circuit of the motor, Even if a failure such as contact welding occurs, the motor is safely stopped (see, for example, Patent Document 1).
However, in this method, since the drive power supply is turned on and off repeatedly every time parts are supplied or removed after work, the frequency of maintenance such as replacement of the magnetic contactor increases. There is a strong demand for greatly extending the service life of relay contacts.

A driving device that controls a plurality of motors used in an automatic machine includes a rectifier circuit that converts alternating current connected to a relay device such as an electromagnetic contactor into direct current, a smoothing circuit that smoothes the voltage after rectification, and a smoothing circuit. The inverter unit is composed of a plurality of inverter circuit units for converting the subsequent DC voltage for driving the motor, and the inverter unit is controlled by a PWM command signal generated by the CPU based on the operation of the automatic machine.
In this configuration, since a capacitor is used in the smoothing circuit on the load side of the relay device, it is a capacitor load type circuit. When the drive power supply is turned on and off, the smoothing capacitor has a large charging current and There is a problem that the interruption current flows, damages the relay contact, and cannot extend the life of the contact.

The contact life of the magnetic contactor is known to cause an arc between the contacts due to the inrush current at the time of turning on and the breaking current at the time of breaking, and the contact becomes rough. In the conventional example, a proposal to insert an inrush current limiting resistor only during the charging period of the smoothing capacitor (see, for example, Patent Document 2), or a proposal to cut off only at a low current as a second conventional example (for example, Patent Document 3). In addition, as a third conventional example, there is a method of opening and closing a relay contact in the vicinity of zero volts of an AC power supply (see, for example, Patent Document 4).
As described above, the conventional power supply device for an automatic machine is intended to extend the life by reducing the current when the contact of the electromagnetic contactor that supplies and shuts off the power is opened and closed.
JP-A-11-113274 JP-A-5-168248 Japanese Patent Laid-Open No. 11-297176 JP 2000-340057 A

  In the first conventional example (Patent Document 2), a large inrush current is suppressed by supplying power through a resistor when the power is turned on. However, if the resistance value of the resistor is increased, the charging time to the smoothing capacitor increases, and the inverter This increases the time until the motor can be driven. This is because the time until the automatic machine can start operating after turning on the drive power is increased. Therefore, considering the productivity, the resistance value of the resistor is reduced and the time until the automatic machine can start operating is desired. . However, if the resistance value is reduced, the inrush current cannot be sufficiently suppressed. Therefore, each time the drive power is turned on, the resistor conductor instantaneously heats up due to its heat generation, and the relay is turned off after the circuit is closed. Therefore, the resistor conductor is cooled. Resistor conductors are repeatedly expanded and contracted due to heat at this time, and the resistance conductor may cause a disconnection failure due to fatigue due to repeated expansion and contraction. It is necessary to select one having a large outer shape, which is a major obstacle when it is desired to reduce the size of a control device for an automatic machine. There are also obstacles to cost reduction. In addition, since there is no measure to control the cut-off current when the power is cut off, an operation such as an emergency stop is performed while the motor is running, and when the relay device is cut off, a large current is cut off, An arc is generated, and therefore, the contact surface is roughened, and fusion and welding are likely to occur, and the contact life may be shortened.

  In the second conventional example (Patent Document 3), the contact is opened after the current falls below a predetermined value. As a means for ensuring safety in an automatic machine, the motor is driven by an emergency stop operation or the like in an emergency. Since the operation is performed by shutting off the power supply and stopping the operation of the automatic machine, if an emergency stop operation that cuts off the drive power supply is performed, the relay device contact must be set regardless of whether the automatic machine is operating or stopped. It is necessary to open the circuit, and it does not open when the current of the automatic machine is operating or accelerating operation is greater than the specified value. In this example, the power cannot be shut down such as emergency stop. There is a problem that cannot be done.

  The third conventional example (Patent Document 4) is a method of opening and closing a relay contact near zero volts of an AC power supply, but when the contact is closed, the charging current to the smoothing capacitor flows as an inrush current, so the capacity of the contact is A specification sufficient for this is required. In addition, since the load has a smoothing capacitor in the open circuit, the current cannot be completely cut off at the instant of the open circuit due to the capacitance, and an arc is generated at the contact point.

In the above-mentioned conventional example, a measure for selecting a relay device having a large contact capacity specification so as to be suitable for the switching frequency of the relay device contact against the inrush current at the time of contact closing and the arc generated between the contacts at the time of opening circuit. However, this measure has a problem of increasing the size of the control device when applied to a control device for an automatic machine that requires a smaller size and requires a smaller size of the relay device. In addition, there was a problem that caused an increase in cost.
Further, in the method of Patent Document 1, although two electromagnetic contactors are used and the drive power supply can be reliably shut down even if one of the faults occurs, a plurality of electromagnetic contactors are manufactured. Due to variations, the specifications are not exactly the same. For example, the difference in contact operation and return time results in contact damage caused by turning on / off the drive power concentrated on the contact of one electromagnetic contactor. The effect of extending the contact life was small.
Therefore, the present invention has been made in view of such problems, and provides an automatic machine that supplies a highly reliable power supply with a long life to an automatic machine drive device and has no problem in ensuring safety. An object of the present invention is to provide a control device.

In order to solve the above problem, the present invention is configured as follows.
The invention according to claim 1 includes a first electromagnetic contactor that opens and closes a contact by a first signal, and a second electromagnetic contactor that opens and closes a contact by a second signal, and the first electromagnetic contactor The contact of the first electromagnetic contactor and the contact of the second electromagnetic contactor are connected in series with each other, and the power supply device of the automatic machine cuts off the supply of power to the drive power supply circuit of the motor. When both of the contacts of the electromagnetic contactor are closed and power is supplied to the drive power circuit of the motor, the contact between the contact of the first electromagnetic contactor and the contact of the second electromagnetic contactor is closed. It has a predetermined time difference.
The invention according to claim 2 is characterized in that the order of the closing of the contact of the first electromagnetic contactor and the closing of the contact of the second electromagnetic contactor is switched every predetermined number of times of insertion. It is.
The invention according to claim 3 includes a first electromagnetic contactor that opens and closes a contact by a first signal, and a second electromagnetic contactor that opens and closes the contact by a second signal, and the first electromagnetic contactor. In a power supply device for an automatic machine in which a contact of a contactor and a contact of a second electromagnetic contactor are connected in series with each other, and supply and cut-off of power to a drive power circuit of a motor, the contact of the first electromagnetic contactor and the contact When both the contacts of the second electromagnetic contactor are opened and the power supply to the drive power circuit of the motor is cut off, the contact opening of the first electromagnetic contactor and the contact of the second electromagnetic contactor are opened. It has a predetermined time difference between them.
The invention according to claim 4 is characterized in that the order of the opening of the contact of the first electromagnetic contactor and the opening of the contact of the second electromagnetic contactor is switched every predetermined number of times of interruption. It is.

According to the first and second aspects of the present invention, a predetermined time difference is generated between the contact of the first electromagnetic contactor and the closed circuit of the second electromagnetic contactor when power is supplied, and the sequence of the closed circuit is changed every predetermined number of times. By switching to, the burden on the relay device contact due to the charging current generated when the power is turned on can be equally shared to each contact, and the life of the contact can be extended.
According to the invention of claim 3 and claim 4, when the power is shut off, a predetermined time difference is generated between the contact of the first electromagnetic contactor and the opening of the second electromagnetic contactor of the previous period, and the order of the opening is further determined. By changing the frequency every time, the burden of the contact due to a large breaking current generated when the power is turned off can be equally shared to each contact, and the life of the contact can be extended.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a circuit diagram showing a configuration of a first embodiment of a power supply device for an automatic machine according to the present invention. In the figure, SW1 and SW2 are contacts that fundamentally supply and shut off power. These are configured by a manual switch such as an emergency stop switch or a contact of a relay, and are opened and closed substantially simultaneously. X1 and X2 are relays, and the coils are excited by the closing of SW1 and SW2, respectively, and the X1-a contact and the X2-a contact are closed. T1 is a timed operation instantaneous return type timer, which closes the T1-a1 contact and the T1-a2 contact with a predetermined time delay t1 from the moment when the X1-a contact and the X2-a contact are closed, and the X1-a contact. And the opening of the X2-a contact instantly opens the T1-a1 contact and the T1-a2 contact. T2 is an instantaneous operation time-return type timer that closes the T2-a1 contact and the T2-a2 contact at the instant when the X1-a contact and the X2-a contact are closed, and opens the X1-a contact and the X2-a contact. The T2-a1 contact and the T2-a2 contact are opened with a delay t2 of a predetermined time from the moment. X3 and X4 are electromagnetic contactors. X3 is excited when the SW1 and T1-a1 contacts are closed simultaneously, or when the T2-a1 and X5-1 contacts are closed simultaneously, closing the X3-a contact and simultaneously opening the auxiliary contact X3-b. To do. X4 is excited when the SW2 and T1-a2 contacts are closed simultaneously, or when the T2-a2 and X5-2 contacts are closed simultaneously, closing the X4-a contact and simultaneously opening the auxiliary contact X4-b. . X5 is a ratchet relay or two-pole stepping relay that is excited when the X3-b auxiliary contact and the X4-b auxiliary contact are closed simultaneously, and alternately opens and closes the X5-1 contact and the X5-2 contact each time it is excited. To do. The drive power supply of the machine is connected to the drive unit serving as a load via the X3-a contact and the X4-a contact connected in series, and is driven when both the X3-a contact and the X4-a contact are closed. Power is supplied to the power supply.

The operation is as shown in the timing chart of FIG. In FIG. 2, the signal is HIGH when the coil is excited or the contact is closed, and the LOW state is when the coil is not excited or when the contact is open. The operation of FIG. 2 shows a case where the power is turned on and off twice, and when attention is paid to the operation of the X3-a contact and the X4-a contact that directly control the power supply / off, When the power is turned on, the X4-a contact closes late with respect to the X3-a contact and opens quickly, but when the power is turned on the next time, the X3-a contact becomes opposite to the X4-a contact. The operation is such that the circuit is closed after a delay and the circuit is opened early. Although not shown in the subsequent figures, such an alternating operation continues. It is the contact side that closes with a delay when a large current change is applied when power is supplied, and the contact side that opens a circuit quickly when a large current change is interrupted when the power is interrupted. Become. Since the load is alternately shared by the X3-a contact and the X4-a contact in this way, the life of the contact can be extended as a whole.
The part different from Patent Document 2 and Patent Document 3 or Patent Document 4 in which the present invention is cited as a conventional example is a part having a mechanism in which a plurality of contacts alternately bear a load as described above.

  FIG. 3 is a circuit diagram showing the configuration of the second embodiment. In the figure, CPU1 and CPU2 are arithmetic processing devices for controlling the coils of the first electromagnetic contactor X3 and the second electromagnetic contactor X4 connected in series, respectively. And given instructions to shut off. FF1 is a D-type flip-flop, which receives a signal for turning on / off the driving power from the CPU 3, and inverts the output state when the magnetic contactor is cut off, that is, at the fall of the signal. The output of FF1 is given to the CPU 1 and CPU 2 as signals of opposite polarities, and the state is inverted every time the drive power supply is shut off. The CPU 1 receives a drive power-on signal from the CPU 3, and when the signal from the FF 1 is HIGH, the coil of the electromagnetic contactor X3 is relayed with a time delay of t1 from the opening of the auxiliary contact X4-b of the electromagnetic contactor X4. Excited via DR1. At the time of shut-off, the excitation of the coil X3 is stopped with a delay of t2. When the signal from the FF 1 is LOW, the excitation of the X3 coil is immediately started / stopped in response to the drive power on / off signal from the CPU 3. The CPU 2 operates in the same manner as the CPU 1 for each input signal. Only when both the X3 contact X3-a and the X4 contact X4-a are closed, the drive power is output to the drive unit.

  The operation is as shown in the timing chart of FIG. In FIG. 4, (1) to (5) represent the logic state of the signal at each node. In other cases, the signal HIGH state represents the coil excitation state or the contact closed state, and the LOW state represents It represents a non-excited state of the coil or an open state of the contact. Focusing on the operation of the X3-a contact and the X4-a contact that directly control power supply / shutoff, when the power is turned on for the first time, the X3-a contact is closed with respect to the X4-a contact, Although the circuit is opened after a delay, the X4-a contact is closed with respect to the X3-a contact when the power is turned on the next time, and the circuit is opened after the disconnection. Although not shown in the subsequent figures, such an alternating operation continues. It is the contact side that closes with a delay when a large current change is applied when power is supplied, and the contact side that opens a circuit quickly when a large current change is interrupted when shutting off. Become. Since the load is alternately shared by the X3-a contact and the X4-a contact in this way, the life of the contact can be extended as a whole.

In these embodiments, the order of turning on and off the magnetic contactor is changed each time by outputting a signal from the D-type flip-flop to the CPU 1 and the CPU 2, but a signal corresponding to this signal is sent from the CPU 3 to the CPU 1 and the CPU 2. When the output is made, the switching of the order is based on a program of the CPU 3 or a preset parameter.
In the embodiment, the number of electromagnetic contactors is two. However, by further increasing the number of electromagnetic contactors, their relay drivers, and the control circuit CPU, the drive power supply can be cut off with increased reliability. It is clear that
Here, for example, when the method of Patent Document 2 is adopted, the on-current or on-off current at the time of turning on and off of each electromagnetic contactor can be reduced, the life of the contact is further extended, and the present invention is adopted. The maintenance frequency of the electromagnetic contactor of the automatic machine can be further reduced.

  As described above, the life of the contacts can be extended by connecting a plurality of contacts in series, providing a predetermined time difference between each open circuit and each closed circuit, and changing the order of the open circuit and the closed circuit every predetermined number of times. Therefore, the present invention can be widely applied not only to the power supply device but also to the purpose of extending the contact life.

1 is a circuit diagram of a power supply device for an automatic machine showing a first embodiment of the present invention. The timing chart figure which shows the operation | movement of the power supply device of 1st Example of this invention. Circuit diagram of a power supply device for an automatic machine showing a second embodiment of the present invention Timing chart showing the operation of the second embodiment of the present invention.

Explanation of symbols

SW1 Manual switch or relay contact SW2 Manual switch or relay contact X1 Relay X2 Relay X3 Electromagnetic contactor X4 Magnetic contactor X5 Ratchet relay or 2-pole stepping relay T1 Timed operation instantaneous recovery type timer T2 Instantaneous operation timed recovery type timer CPU1 Calculation Processing device 1
CPU2 arithmetic processing unit 2
CPU3 Host processor FF1 D flip-flop DR1 Relay driver 1
DR2 Relay driver 2

Claims (4)

A first electromagnetic contactor that opens and closes a contact in response to a first signal; and a second electromagnetic contactor that opens and closes a contact in response to a second signal; and the contact of the first electromagnetic contactor and the second electromagnetic contactor In a power supply device for an automatic machine, the contacts are connected in series with each other and the power supply to the motor drive power supply circuit is cut off from the supply of power.
When both the contact of the first electromagnetic contactor and the contact of the second electromagnetic contactor are closed and power is supplied to the drive power supply circuit of the motor, the closed circuit of the contact of the first electromagnetic contactor and the first contact 2. A power supply device for an automatic machine characterized by having a predetermined time difference between the contact point of the electromagnetic contactor and the closed circuit.   2. The power supply device for an automatic machine according to claim 1, wherein the order of the closing of the contact of the first electromagnetic contactor and the closing of the contact of the second electromagnetic contactor is exchanged every predetermined number of times. A first electromagnetic contactor that opens and closes a contact in response to a first signal; and a second electromagnetic contactor that opens and closes a contact in response to a second signal; and the contact of the first electromagnetic contactor and the second electromagnetic contactor In a power supply device for an automatic machine, the contacts are connected in series with each other and the power supply to the motor drive power supply circuit is cut off from the supply of power.
When both the contact of the first electromagnetic contactor and the contact of the second electromagnetic contactor are opened and the power supply to the motor drive power circuit is cut off, the opening of the contact of the first electromagnetic contactor and the first contact 2. A power supply device for an automatic machine having a predetermined time difference between the contact opening of the two magnetic contactors.   4. The power supply device for an automatic machine according to claim 3, wherein the order of the contact opening of the first electromagnetic contactor and the contact opening of the second electromagnetic contactor is switched every predetermined number of times of interruption.

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