JPH09161638A - Electromagnetic contactor with temperature correcting unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain the current, which flows in a coil, at a constant value, and to hold the attractive force of an electromagnet constant independently of temperature so as to improve the durability of a mechanism unit by connecting a variable resistor in series to an electromagnet exciting coil of an electromagnetic contactor so as to correct the temperature resistance value of the coil. SOLUTION: Terminals 1b, 1c of a temperature correcting unit, which is built in a variable resistor VR, are inserted into exciting coil terminals 9a, 9b of an electromagnetic contactor 9, and a fitting part 9c of the electromagnetic contactor 9 and a locking claw of the unit 1 are engaged with each other for installation. At this stage, the variable resistor is connected to the exciting coil in series to a power source, and resistance value thereof can be adjusted by an adjusting knob 1a. The current flowing in the coil is maintained constant and the attractive force of the electromagnet is maintained constant by adjusting the variable resistance value so that a sum of the resistance value of the coil and the variable resistance value is maintained constant in response to the peripheral temperature, and an excessive impact to be applied to the mechanism unit at the time of excitation can be prevented so as to improve the durability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic contactor with a temperature correction unit in which a change in resistance of an exciting coil in an electromagnetic contactor due to ambient temperature is corrected to eliminate a change in attraction force due to ambient temperature.

[0002]

2. Description of the Related Art An electromagnetic contactor utilizes an electromagnetic force generated by passing an electric current through a coil of an electromagnet to open and close a contact to attract a movable part to a fixed core to bring the movable contact into contact with the fixed contact. Using a return spring, the movable part is pulled away from the fixed core to open the contact when there is no current. The allowable temperature range of this electromagnetic contactor is -5 ° C to + 50 ° C, and the resistance value of the coil using copper wire decreases about 0.4% when the temperature decreases by 1 ° C. The coil current increases, the attraction force to the movable part increases, and the durability of the mechanism part decreases.

When a DC electromagnet and an AC electromagnet are compared, the influence of the DC electromagnet, in which the current is determined only by the resistance value, is remarkable, but in the AC electromagnet, small products have a large ratio of the resistance value to the impedance, and this resistance value change is ignored. Can not. Explaining the DC electromagnet as an example, assuming that the coil resistance value at the upper limit temperature of 50 ° C. is 100%, the coil resistance value is 81% at −5 ° C., and when converted to the supply voltage, the overexcitation is 123%.

Since the attractive force of the electromagnet is approximately proportional to the square of the supply voltage, the impact of exciting the electromagnet becomes large at low temperature, and the fatigue of the core and other mechanical parts is accelerated. According to the result of the experiment, the durability of the mechanical portion was decreased in inverse proportion to the 4th to 5th power of the supply voltage. Therefore, the durability of the mechanical part at -5 ° C is 50
It decreases to about 40% of ℃.

[0005]

As described in the prior art, when the resistance value of the coil of the electromagnet changes due to the change of ambient temperature, the attractive force of the electromagnet changes, and when the ambient temperature is low, the There is a problem that the suction force is increased and the durability of the mechanism part is reduced. An object of the present invention is to provide an electromagnetic contactor in which the attractive force of an electromagnet is not affected by temperature.

[0006]

According to the first aspect of the present invention,
An electromagnetic contactor including a coil that generates an electromagnetic force when a power supply voltage is applied, the variable resistor having a resistance value adjustable in series with the coil in accordance with a coil resistance value that changes depending on ambient temperature. It is characterized by connecting.

Further, according to the present invention, in the electromagnetic contactor with a temperature compensation unit according to claim 1, the variable resistor is characterized in that the slider is operated in conjunction with an adjusting knob having a temperature scale. Further, according to the present invention, in the electromagnetic contactor with a temperature correction unit according to claim 1 or 2, the variable resistor is unitized so as to be directly connectable to the coil terminal.

According to a fourth aspect of the present invention, there is provided an electromagnetic contactor including a coil for generating an electromagnetic force when a power supply voltage is applied, wherein the temperature characteristic value of the temperature sensitive element due to a temperature change causes the ambient temperature to change. It is characterized in that a conversion circuit for generating a voltage corresponding to a dependent coil resistance value is connected to the coil. Further, according to the present invention, in the electromagnetic contactor with a temperature correction unit according to claim 4, the temperature sensitive element is a temperature sensitive resistor whose resistance value is determined by temperature, and the voltage conversion circuit causes a constant current to flow through the temperature sensitive resistor. 2 is a structure of a voltage circuit that generates a voltage that increases or decreases in accordance with

Further, according to the present invention, in the electromagnetic contactor with a temperature correction unit according to claim 5, the temperature sensitive resistor is a thermistor connected in series with a reference resistor for a reference voltage, and the voltage circuit includes a reference resistor, Transistor, feedback resistor,
A circuit that includes a regulator that keeps the reference voltage constant while increasing or decreasing the output voltage according to the increase or decrease in the feedback voltage.

According to the present invention, in the electromagnetic contactor with temperature correction unit according to any one of claims 4 to 6, the voltage conversion circuit is unitized and can be directly connected to the coil terminal.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a variable resistance is connected in series with a coil of an electromagnetic contactor, the value of the variable resistance is determined according to the ambient temperature, and the total resistance value is made equal to the resistance value of 50 ° C.
In addition, a voltage conversion circuit that allows a constant current to flow is connected to the coil resistance that depends on the temperature of the electromagnetic contactor to improve the durability of the mechanism section.

[0012]

1 shows an electromagnetic contactor with a temperature compensation unit according to an embodiment of the present invention. The electromagnetic contactor 9 has coil terminals 9a and 9b protruding on one side surface and this coil terminal 9
A recessed mounting portion 9c is formed at the bottom of a, 9b. The temperature correction unit 1 is composed of an adjustment knob 1a having a temperature scale, an input terminal 1b, a terminal 1c, a holding piece 1d, and a unit incorporating a variable resistor described later.

FIG. 2 is a rear perspective view of the temperature correction unit 1 described above. In addition to the terminal 1c and the holding piece 1d, a pair of elastic engaging claws 1e are formed. The coil terminal 9a shown in FIG. Further, the temperature correction unit 1 is attached to the electromagnetic contactor by connecting the coil terminal 9b to the holding piece 1d and the mounting portion 9c to the pair of engaging claws 1e. The mounting itself of such a unit is well known from Japanese Utility Model Laid-Open Publication No. 3-94744 (the name of the device is "Magnetic contactor with surge absorbing unit").

FIG. 3 is a diagram showing the internal wiring of the electromagnetic contactor with a temperature correction unit, which is one terminal A1 of the exciting coil L.
Power is supplied to (the coil terminal 9b in FIG. 1) and the other end A3 (the coil terminal 9a in FIG. 1) of the exciting coil L and the other end A3 (the input terminal 1b in FIG. 1) of the variable resistor VR, which has one end connected thereto. Connecting. That is, both ends of the variable resistor VR built in the temperature correction unit 1 are connected to the input terminals 1b and 1c, the terminal 1c is connected to the coil terminal 9a, and the input terminal 1
The variable resistor VR is connected in series to the exciting coil by connecting a power source to the coil b and the coil terminal 9b.
The slider of R is connected to the adjustment knob 1a, and the adjustment knob 1a
The resistance value of the variable resistor VR is changed by operating.

FIG. 4 is a diagram for explaining a method of using the variable resistance of FIG. 3, in which the total resistance Rt = 1 of the variable resistance Rv is adjusted by adjusting the operating temperature range of −5 ° C. to + 50 ° C. to the change of the coil resistance Rl.
The adjustment knob 1a shown in FIG. The electromagnetic contactor 9 of FIG. 1 is a conventional standard product, but a structure in which a temperature correction unit is incorporated and the adjusting knob is exposed to the outside of the electromagnetic contactor is also possible.

FIG. 6 is a diagram summarizing other main points of the present invention, and the numerical values are examples. The thermistor of the temperature conversion element used in the present invention has a type in which the resistance value increases or decreases depending on the temperature rise, and here the positive characteristic as shown in the figure is used. That is, the linear characteristics are 55 kΩ at −10 ° C. and 110 kΩ at 60 ° C. The applied voltage is 100 at 50 ° C.
At V, -5 ° C, the linear characteristic is set to 81V in accordance with the value of the conventional technique. When the ambient temperature is low, the low resistance value of the thermistor is used to lower the voltage supplied to the coil to make the current constant.

FIG. 5 is a specific example of FIG. 6 in which the input voltage is Vi and the output voltage is Vo. The regulator 51 receives 110V which is the input voltage Vi, and lowers the output voltage by the voltage drop of the signal terminal of the symbol Vg, and the characteristic thereof is shown in FIG. When the output is 100V, the voltage drop from the voltage of the signal terminal, for example, if 10V, the output is 10V
Go down to 90V.

Further, in FIG. 5, the reference resistor 54 and the resistor 5
2, the thermistor 53 is connected in series, and the two transistors 56 and 57 and the feedback resistor 58 are connected as shown in the figure. According to this configuration, the current Is flowing through the reference resistor 54 and the current Ib flowing through the resistor 52 are almost equal to each other, but Ib is slightly larger by the base current of the transistor 56. Hereinafter, each characteristic when the ambient temperature is slightly lowered from 50 ° C. will be described.

The resistance value of the thermistor 53 decreases with a slight decrease in temperature, and since Vo is constant, the current Is increases slightly and the reference voltage Vm of the reference resistor 54 decreases a little. Since the base voltage of the transistor 56 drops, the transistor 56
The voltage Vc at the collector of the device decreases. Since the base voltage of the transistor 57 decreases, the collector current Ir decreases a little and the voltage of the feedback resistor 58 decreases, and the voltage of each terminal of the two transistors decreases a little more than at 50 ° C. and becomes stable.
Because of the characteristics described above, the regulator 51 has the signal terminal Vg.
The output voltage Vo is reduced by an amount corresponding to the voltage drop of 1 to make the current Is the same as that at 50 ° C.

This is because the transistor 56 increases the amplification factor together with the transistor 57 to minimize the change in the base current of the transistor 56 with respect to the change in the feedback voltage, and the transistor 56 can be omitted if rough temperature compensation is sufficient. . The resistor 52 is for reducing the rate of change in the resistance value of the thermistor 53 and for lowering the constant current value. In this example, the same voltage change as the voltage change of the thermistor is generated in the regulator, but it is of course possible to make it proportional to the voltage change of the thermistor and to use another temperature sensitive element.

With this configuration, the voltage conversion circuit is unitized in place of the temperature correction unit 1 in FIG. 1, and Vi is connected to the input terminal 1b, Vo is connected to the coil terminal 9a, and 0V is connected to the coil terminal 9b. be able to.

[0022]

According to the present invention, a variable resistor whose resistance value is adjusted according to the ambient temperature is connected in series with the coil, and the attracting force is made constant even if the ambient temperature changes so that the electromagnetic contactor can be operated. The durability of the mechanism section can be improved. In addition, the variable resistor is provided with an adjustment knob with a temperature scale so that the variable resistance can be easily adjusted to improve the durability of the mechanical part of the electromagnetic contactor, and it can be easily combined with the conventional standard electromagnetic contactor. The durability can be improved at low cost.

Further, according to the present invention, the durability of the mechanism portion of the electromagnetic contactor can be improved by supplying a constant current to the coil resistance which depends on the temperature, and it can be easily coupled to the conventional standard electromagnetic contactor. The durability can be improved at low cost, and the temperature of the electromagnetic contactor can be automatically corrected with low power.

[Brief description of the drawings]

1 is a perspective view of an electromagnetic contactor showing an embodiment of the invention according to claim 1;

FIG. 2 is a rear perspective view of the temperature correction unit shown in FIG.

FIG. 3 is an internal wiring diagram of FIG.

FIG. 4 is an explanatory diagram for adjusting the total resistance of the invention according to claim 1;

FIG. 5 is a circuit diagram of an embodiment of the invention according to claim 4;

6 is an explanatory diagram of the main contents of FIG.

FIG. 7 is a characteristic diagram of the regulator of FIG.

[Explanation of symbols]

 1 Temperature Correction Unit 1a Adjustment Knob 1b Terminal 1c Terminal 1d Holding Piece 9 Magnetic Contactor 9a Coil Terminal 9b Coil Terminal 51 Regulator 53 Thermistor 54 Reference Resistance 56 Transistor

Claims (7)

[Claims] 1. An electromagnetic contactor comprising a coil for generating an electromagnetic force by applying a power supply voltage, wherein a resistance value is provided in series with the coil in response to a coil resistance value that changes depending on ambient temperature. An electromagnetic contactor with a temperature compensation unit, characterized in that an adjustable variable resistor is connected. 2. An electromagnetic contactor with a temperature compensation unit according to claim 1, wherein the variable resistor has a temperature compensation unit in which a slider is operated in conjunction with an adjusting knob having a temperature scale. Electromagnetic contactor. 3. The electromagnetic contactor with a temperature compensation unit according to claim 1, wherein the variable resistor is unitized so as to be directly connectable to a coil terminal. vessel. 4. An electromagnetic contactor having a coil for generating an electromagnetic force by applying a power supply voltage, wherein a voltage corresponding to a coil resistance value depending on ambient temperature is set by a temperature characteristic value of a temperature sensitive element due to temperature change. An electromagnetic contactor with a temperature compensation unit, characterized in that the conversion circuit to be generated is connected to a coil. 5. The electromagnetic contactor with a temperature compensation unit according to claim 4, wherein the temperature sensitive element is a temperature sensitive resistance whose resistance value is determined by temperature, and the voltage conversion circuit applies a constant current to the temperature sensitive resistance. An electromagnetic contactor with a temperature correction unit, which is a voltage circuit that generates a voltage that increases and decreases according to temperature. 6. The electromagnetic contactor with a temperature correction unit according to claim 5, wherein the temperature sensitive resistor is a thermistor connected in series with a reference resistor for a reference voltage, and the voltage circuit includes a reference resistor, a transistor, and An electromagnetic contactor with a temperature correction unit, which is a circuit including a feedback resistor and a regulator that keeps a reference voltage constant while increasing / decreasing an output voltage according to an increase / decrease in the feedback voltage. 7. An electromagnetic contactor with a temperature correction unit according to claim 4, wherein the voltage conversion circuit is unitized and can be directly connected to the coil terminal. With magnetic contactor.