JP2558029B2 - Resistor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic mold type resistor suitable as a current limiting resistor.

[0002]

2. Description of the Related Art Conventionally, for example, a ceramic mold type resistor 100 for limiting an energizing current is shown in FIGS.
As shown in FIG. 3, a coil 101 for limiting the current supplied to the fan motor, a ceramic case 102 for housing the coil 101, a heat-resistant cement 103 filled in the ceramic case 102, and a ceramic case 102 A terminal 105 connected to the terminal portion 104 of the coil 101, a terminal 107 connected to the terminal 105 via a spring 106 outside the ceramic case 102, and a spring 106 to the terminal 105.
And a thermal fuse 108 for contacting with each other. The temperature fuse 108 melts when the heat of the coil 101 transmitted through the terminal 105 rises above a predetermined value, and the terminal 105 and the spring 106 are melted.
By cutting off the connection with the coil 101, the coil 101 is prevented from being overheated when an overcurrent flows through the coil 101.

[0003]

However, in the conventional energization current limiting resistor 100, the terminal 105 is used.
Since brass is used as the material of, the heat conduction performance to the thermal fuse 108 is poor. Therefore, even if the fan motor is locked and an overcurrent flows through the coil 101 to overheat the coil 101, the surface temperature of the ceramic case 102 becomes extremely high before the thermal fuse 108 melts, causing various problems. It was An object of the present invention is to provide a resistor having improved heat conduction performance from a resistance element to a thermal fuse.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a resistance element for limiting a current flowing to an electric appliance, a heat-resistant case for accommodating the resistance element therein, and a heat-resistant case arranged outside the case and melted are provided. A thermal fuse for stopping energization of the resistance element, a first connection section connected to the terminal section of the resistance element in the case, and integrated with the first connection section,
A second connection part connected to the temperature fuse outside the case; and a heat transfer part extending from the first connection part so as to cover a lateral side in the longitudinal direction of the resistance element or an end face of the resistance element. Adopted technical means with terminal.

[0005]

According to the present invention, since the heat transfer portion of the terminal is extended from the first connection portion so as to cover the longitudinal side of the resistance element or the end face of the resistance element, the heat generated by the resistance element is transmitted to the terminal. It will be easier. For this reason, since the heat conduction performance to the thermal fuse is improved, the thermal fuse is melted and the power supply to the resistive element is stopped by the time the surface temperature of the heat resistant case reaches a temperature at which various problems occur. It

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A resistor according to the present invention will be described based on an embodiment shown in FIGS. FIG. 1 and FIG. 2 are diagrams showing a current limiting resistor to which an embodiment of the present invention is applied. The energization current limiting resistor 1 is a ceramic mold type resistor for reducing the rotation speed of a fan motor (not shown) of a blower for an automobile, and includes a coil 2, a ceramic case 3, a thermal fuse 4 and a first resistor. 1,
It is composed of the second terminals 5 and 6.

The coil 2 is the resistance element of the present invention,
An electric resistance is applied to the fan motor to limit the energization current to the fan motor, and the amount of heat generation increases as the energization current increases. The coil 2 has a winding portion 9 around which a nickel conductive wire is wound, and a terminal portion 11 extending from an end surface 10 of the winding portion 9. Ceramic case 3
Is a heat-resistant case of the present invention, in which the first terminal 5 is inserted into the holding portion 12 that holds the winding portion 9 of the coil 2, the opening portion 13 formed above the drawing, and the holding portion 12. It has an insertion hole 14. The holding portion 12 is a curved bottom portion 1 for facilitating holding of the winding portion 9 of the coil 2.
5, a side wall portion 16 erected above the bottom portion 15 in the drawing, and an end wall portion 17 erected parallel to the end surface 10 of the winding portion 9. The holding portion 12 is filled with heat-resistant cement 18 so as to cover the coil 2.

The thermal fuse 4 connects the first and second terminals 5 and 6 by melting a temperature sensitive element 19 made of a ternary alloy of lead and bismuth or a low melting point metal to which cadmium, indium, zinc, etc. are added. L-shaped spring 2
By separating 0 from the first terminal 5, the connection between the coil 2 and the fan motor is cut off. The first and second terminals 5 and 6 are made of brass and are erected on a base 21 made of phenol resin. First
The terminal 5 includes a first connecting portion 22 that is connected to the terminal portion 11 of the coil 2 in the ceramic case 3 by a joining method such as caulking, a second connecting portion 23 that is connected to the thermal fuse 4 and the spring 20 outside the ceramic case 3, A flat plate-shaped heat transfer portion 24 extending from the first connecting portion 22 so as to cover a side of the winding portion 9 of the coil 2 in the longitudinal direction, and an end surface 10 of the winding portion 9 from the first connecting portion 22. It has an arc plate-shaped heat transfer portion 25 extended so as to cover it. The second terminal 6 is connected to an automobile power source (not shown) via a fan motor.

The operation of this energizing current limiting resistor 1 is shown in FIG.
A brief description will be given with reference to FIG. When a current flows through the winding part 9 of the coil 2, a predetermined electric resistance is given to the fan motor connected to the winding part 9 of the coil 2 via the first and second terminals 5 and 6, the spring 20 and the like. The fan motor rotates at a low speed due to the limitation of the current supplied to the fan motor.

When an overcurrent flows through the winding portion 9 of the coil 2 due to the fan motor locking or the like, the winding portion 9 of the coil 2 generates heat. The heat generated in the winding part 9 of the coil 2 is intensively transferred to the first terminal 5. That is,
The heat generated in the winding portion 9 of the coil 2 is the same as the winding portion 9 of the coil 2.
The heat is transferred intensively to the heat transfer portion 24 that exists laterally in the longitudinal direction or to the heat transfer portion 25 that exists near the end surface 10 of the winding portion 9. Then, the heat transferred to the heat transfer parts 24 and 25 is quickly transferred to the second connection part 23 via the first connection part 22, and the second
The temperature of the connecting portion 23 quickly rises to the melting temperature of the temperature sensitive element 19 of the thermal fuse 4.

Therefore, the ceramic case 3 is heated by the heat generated in the winding portion 9 of the coil 2 via the holding portion 12.
Before the surface temperature of the temperature reaches the ignition temperature of dust or the like adhering to the surface of the ceramic case 3, the temperature sensitive element 1 of the thermal fuse 4
Since the 9 melts, the spring 20 moves the first terminal 5
Apart from the above, by disconnecting the coil 2 from the fan motor, overheating of the coil 2 and overheating of the surface temperature of the ceramic case 3 are eliminated.

In the case of the present embodiment, when the fan motor lock test is performed, the fusing time of the temperature fuse 4 becomes shorter than that of the conventional one by about 50 seconds.
Surface temperature rises only about 200 ° C lower than the conventional one.

[Modification] Either one of the heat transfer parts 24 and 25 may be provided, and the heat transfer part may be provided around the winding part 9 of the coil 2. In the present embodiment, the present invention is applied to the resistor that limits the energizing current to the fan motor, but the present invention may be applied to the resistor that limits the energizing current to various electric appliances. In addition to the coil-shaped element, a planar element or a rod-shaped element may be used as the resistance element.
Although brass is used as the material of the first terminal 5 in the present embodiment, a conductor (for example, silver or silver alloy) having a higher thermal conductivity than brass may be used as the material of the terminal.

[0014]

According to the present invention, since the performance of heat conduction from the resistance element to the thermal fuse can be improved, the thermal fuse can be heated before the surface temperature of the heat-resistant case reaches a temperature at which various problems occur. Thus, the energization of the resistance element can be stopped.

[Brief description of drawings]

FIG. 1 is a side view showing a conducting current limiting resistor applied to an embodiment of the present invention.

FIG. 2 is a front view showing a conduction current limiting resistor applied to one embodiment of the present invention.

FIG. 3 is a side view showing a conventional energization current limiting resistor.

FIG. 4 is a front view showing a conventional energization current limiting resistor.

[Explanation of symbols]

 1 Resistor for Energizing Current Limit 2 Coil (Resistive Element) 3 Ceramic Case (Heat Resistant Case) 4 Thermal Fuse 5 1st Terminal 22 1st Connection Part 23 2nd Connection Part 24 Heat Transfer Part 25 Heat Transfer Part

Claims (1)

(57) [Claims] 1. A resistance element for limiting an electric current flowing through an electric appliance; (b) a heat-resistant case for accommodating the resistance element inside; (c) an outside of the case; and melting. A thermal fuse for stopping energization to the resistance element by: (d) a first connecting portion connected to a terminal portion of the resistance element in the case; And a second connecting portion connected to the temperature fuse, and a terminal having a heat transfer portion extending from the first connecting portion so as to cover a lateral side in the longitudinal direction of the resistance element or an end face of the resistance element. Equipped resistor.