JPS63237319A - Reliability securing apparatus for switch contact for motor control - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a motor control switch configured to turn on and off when the contact current is zero when controlling the drive of a motor such as a servo motor. This invention relates to a device for ensuring reliability of contacts.

[Prior art and problems to be solved by the invention] Today,
When performing drive control of a motor, the drive control circuit is normally kept in an ON state while the system is in operation as a measure to avoid system abnormalities due to failure of the motor or actuator.1. The so-called fail-safe system controls the switch contacts to turn OFF after the drive current for the motor, etc. is cut off by the main switch OFF command, and if a failure occurs, it is detected and the motor drive is stopped immediately. FS) Some models are equipped with a relay switch. By the way, in such a relay switch, if the switch contacts are turned ON and OFF when the contact current is zero, dust or gas components in the air may adhere to the switch contacts, or the switch contacts may be damaged. An insulating film may form on the switch contact surface due to oxidation.

This tends to increase contact resistance. Substances that increase the contact resistance of these contacts can be
Normally, this does not cause a problem when the switch contact is turned OFF because it can be removed by the arc generated when the switch contact is OFF, but if the switch contact is ON - OFF when the contact current is zero,
In the above case of FF, no arc occurs when the switch contact is OFF.

Therefore, the removing and cleaning effect of the arc cannot be expected, and as a result, the voltage applied to the motor fluctuates due to an increase in contact resistance, resulting in a problem that highly accurate drive control cannot be performed.

[Means for Solving the Problems] In view of the above-mentioned circumstances, the present invention was devised for the purpose of providing a reliability ensuring device for motor control switch contacts that can eliminate these drawbacks. a switch means for switching the switch contact ON-OFF in a state where no power supply current flows in the drive control circuit;
The present invention is characterized in that a contact chattering means is provided which applies intermittent excitation No. 18 to the excitation coil of the switch contact at 08 o'clock of the switch contact to cause the switch contact to chatter.

With this configuration, the present invention purifies the switch contacts of a drive control circuit for a motor etc. by a forced chattering action, prevents an increase in contact resistance, stabilizes the voltage applied to the motor terminals, and achieves high precision. This enables drive control.

[Example] Next, an example of the present invention will be described based on the drawings. In the drawing, 1 is a drive control circuit for a servo motor, B is a battery, E is ground, M is a motor, 2 is a current detector, 3 is a fail-safe (FS) relay switch, and 4 is an actuator. However, the relay switch 3
In this embodiment, normally the main switch Sv is turned on.
The coil 3a is excited in response to a control command from the control unit 5 which inputs the command, thereby switching the switch contact 3b to the ON state. Note that 2 is a current detector, and the current detector 2 detects an abnormal current due to a failure of the motor M, etc., and outputs this to the control unit 5, but this detection signal is not input. The control unit 5 issues a switching command to the OFF side to the relay switch 3 to emergency stop the power supply to the motor M. On the other hand, F
ETl-FET4 is a field effect transistor, and the gates (bases) of the transistors FET1 to FET4 are connected to the control unit 5 side, and ON-OF'F switching is performed according to a control command from the control unit 5. It is designed to do this. The transistors FET1-FET4 receive a control command from the control unit 5 in the ON state, and the transistors FET1. Turn on FET4, transistor FH
Turn off T3 and FET2. As a result, current from battery B flows from transistor FET 1 to motor M to relay switch 3 to transistor FET 4, and vice versa. Turn on FET2:, transistor FET1. By turning off FET4, the current from battery B is transferred from transistor FET3 to relay switch 3 to motor M to transistor FE! The current flows toward T2, thereby enabling forward and reverse drive control of the motor M.

In addition, the base terminals of Trl and Tr2 are connected to the control unit 5, respectively.
(CPIJ), and the collector terminal of the transistor Tri is connected to the relay switch 3.
The coil 3a is connected in series with the coil 3a. For example, when the main switch Sv such as an ignition switch is set to ONL, the control unit 5 (CPU) receives the ON signal.
Transistor Tri turns ON-OF in response to a signal from
F is switched on and off to excite the relay coil 3a multiple times (four times in the embodiment) in a chattering manner. On the other hand, the collector terminal of the transistor Tr2 is connected to the relay coil 38 via the voltage dividing resistor R. When the main switch Sv is set to ONL, the control unit 5 outputs a control command to the transistor TrL in the middle of the intermittent signal (in the embodiment, the transistor Tri
From the third ON signal) to ONL, the ON state is maintained until the main switch Sw is turned OFF. In this case, the voltage applied to the relay coil 3a is controlled by the voltage dividing resistor R. As a result, when the switch contact 3b is chattering, a high voltage is applied to ensure a strong contact pressure, but after that, a low voltage is applied to the switch contact 3b and the relay coil 3a can be prevented from generating heat. In Figure 1, 6 is a fuse.

In an embodiment of the invention constructed as described.

When the relay switch 3 of the motor control circuit 1 is turned ON, an intermittent excitation signal initially flows through the relay coil 3a in response to a command from the control unit 5, and the switch contact 3b becomes ON while chattering. As a result, the insulating film adhering to the switch contact 3b is automatically removed by the mechanical removal and cleaning action of this chattering action, and an increase in contact resistance can be reliably prevented and the voltage applied to the motor M The voltage can be stabilized over a long period of time, and the motor can be controlled with high precision. Moreover, in this case, the voltage applied to the relay coil 3a.

Since the contact pressure is controlled to be high during chattering and low thereafter, the contact pressure during chattering can be increased to further improve the removal and cleaning action.
After chattering, consideration is given to suppressing the heat generation of the relay coil 3a by reducing the voltage to a low voltage, which is advantageous as it becomes an effective protective structure during continuous use of the relay switch 3.

Note that the present invention is of course not limited to the above embodiments, but the present invention can be further developed as follows. That is, as shown in FIG. 3, a resistor is installed in the power supply circuit of the motor M so that the field effect transistors FETl-FET4 pass through the switch contact 3b without interfering with the switch circuit (for example, in parallel with the transistors FET3 and FET2). The resistors R1 and R2 should be set so that the resistance value of R2 is sufficiently high so that when the normal power supply current to the motor M is cut off, the switch contact 3b is turned OFF.
It is set so that a weak current that does not drive the motor M is applied when the current is N. In this case, when the relay switch 3 mentioned above is turned on, an arc is generated only at the moment when the switch contact 3b is turned off during the chattering operation, and therefore, the cleaning action of removing and cleaning both chattering and arc is achieved. This makes it possible to achieve an even better contact protection effect.

[Operations and Effects] In summary, 1. Since the present invention is constructed as described above, the switch contact in the motor drive control circuit includes a switch means that performs ON-OFF switching when the power supply current is zero. However, when this switch contact is turned ON, an intermittent excitation signal flows in response to a command from the control unit, causing it to become ON while chattering.As a result, the insulation that adheres to the switch contact Substances such as coatings can be automatically removed and cleaned, thereby reliably preventing an increase in contact resistance, stabilizing the voltage applied to the motor, and achieving highly accurate drive control.

[Brief explanation of the drawing]

The drawings show an embodiment of the device for ensuring reliability of motor control switch contacts according to the present invention, in which Fig. 1 is a motor drive control circuit diagram and Fig. 2 is a time chart of switch contact operation. . FIG. 3 is a control circuit diagram according to another embodiment. In the figure, M is a motor, FETE, -FET4 is a field effect transistor, Tr1. , Tr2 is a transistor, R is a voltage dividing resistor, R1 and R2 are resistors, S is a main switch, 1 is a motor drive control circuit, and 2 is a current detector. 3 is a fail-safe relay switch, 5 is a control unit (CP
U). Patent Applicant: Mitsuba Electric Co., Ltd. V & Manufacturing Co., Ltd. Figure 1 Figure 3 Procedural Amendment Form 1, Incident Indication Japanese Patent Application No. 62-072318 2, Title of Invention Reliability ensuring device for motor control switch contacts 3, Person making the amendment Relationship to the case: Patent applicant Address: Hirosawa-cho, Kiryu-shi, Gunma Prefecture - Chome 26 Ichiban Name: Mitsuba Electric Manufacturing Co., Ltd. Representative: Hiroshi Kono 4, Agent: 101 f5t03-239- 3511 Removal 03-239-3510 Address Shobido Building, 2-23 Kanda Jimbocho, Chiyoda-ku, Tokyo Figure 1 Figure 3

Claims (1)

[Claims] a switch means for switching the switch contact ON-OFF in a state where no power supply current flows in the motor drive control circuit;
A device for ensuring the reliability of a switch contact for motor control, characterized in that it is provided with contact chattering means for causing the contact to chatter by applying an intermittent excitation signal to an excitation coil of the switch contact when the switch contact is turned on. .