JPH0684439A - Overcurrent protection device - Google Patents

Abstract

PURPOSE:To provide an overcurrent protection device of a compressor motor for use in a refrigerator or the like, which, if some abnormality such as locking of the motor occurs, can shut off current by causing a thermosensitive element to quickly operate and can prevent deterioration of its insulating performance after the operation of the thermosensitive element. CONSTITUTION:A bimetal plate 35, having a pair of traveling contacts 36, 37 at each end molded into the shape of a saucer, is blackened at its thermosensitive surface 35a opposite to a heater 42. Inorganic paint is applied to part or the whole of said heater 42.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overcurrent protection device for a motor for a hermetic compressor used in a refrigerator and a refrigerator.

[0002]

2. Description of the Related Art In recent years, there has been a demand for downsizing and high integration of overcurrent protection devices for compressors used in refrigerators and freezers. For example, the actual Kaihei 3-46941
There is an example as described in the publication.

The above-mentioned overcurrent protection device will be described below with reference to the drawings. 5 and 6 show a conventional overcurrent protection device. In FIG. 5 and FIG. 6, 1 is a resin case made of an insulating material, 2 is a heat responsive element, and 3 is a support plate for supporting one end of the heat responsive element 2.
It is made of a material having a relatively high volume resistance, such as an i-Cr plate, and is connected to the thermoresponsive element by crimping or spot welding, and the other end is welded to the fixing plate 4. A movable contact 5 is fixed to the other end of the thermoresponsive element 2. 6
Is fixed to the external connection terminal 7 with a fixed contact. A heater 8 is welded to a pin connector 9 which is welded to the fixed plate 4 so as to be electrically connected in series with the heat responsive element 2.

The operation of the overcurrent protection device constructed as above will be described below. First, when the motor is locked or the like is abnormal, a large current is applied to the pin connector 9, the heater 8, the fixed plate 4, the support plate 3, the thermal response element 2, the movable contact 5,
It flows to the fixed contact 6 and the external connection terminal 7, and the support plate 3 and the heater 8 having a relatively high volume resistivity generate heat. here,
Since the support plate 3 is connected to the thermo-responsive element 2 by caulking or spot welding, the heat of the support plate 3 quickly heats the thermo-responsive element 2 and assists the heating of the thermo-responsive element by the heat of the heater 8. The response element 2 is snap-operated to open the movable contact 5 and the fixed contact 6 to cut off the current.

[0005]

However, in the above-mentioned conventional structure, the heat responsive element 2 is a metal surface, and the heater 8
Since the heat absorption rate from the heat is low, the operation of the heat responsive element 2 is slow, and there is a problem that it takes time to interrupt the current when the motor is locked or the like is abnormal.

Further, when the heat responsive element 2 operates due to an abnormality such as a motor lock, since it is reversed to the heater 2 side, there is a problem that the insulation performance in contact with the heater 2 deteriorates.

The present invention solves the above-mentioned conventional problems, and provides an overcurrent protection device having excellent performance by rapidly operating a thermal response element and interrupting current when an abnormality such as a motor lock occurs. Is the first purpose. A second object is to provide a highly reliable overcurrent protection device by preventing the insulation performance from deteriorating after the operation of the heat responsive element.

[0008]

An overcurrent protection device of the present invention comprises a first base made of resin, a pair of terminal plates integrally formed with the first base and having fixed contacts, and a pair of movable terminals at both ends. A thermal responsive element having a contact, a second base made of resin, a spring terminal held by the second base and connected to the outside, a heater connected to the spring terminal, and a heater terminal connected to the heater. A plate, a plate spring welded to the heater terminal plate and urged away from one of the pair of terminal plates; and a low melting point metal connecting the plate spring and one of the pair of terminal plates. In the overcurrent protection device, the heat sensitive surface of the heat responsive element facing the heater is blackened.

In addition, a part or all of the heater is configured to be coated with an inorganic paint.

[0010]

The overcurrent protection device of the present invention has a high absorption rate of heat from the heater of the heat responsive element due to the above-described structure.
The heat responsive element can be quickly heated to operate quickly and cut off the current.

Further, since the heater is protected by the paint, it is possible to prevent the insulation performance from being deteriorated due to the arc generation or the like at the time of the reversing operation of the heat responsive element to the heater side, which is highly reliable.

[0012]

An embodiment of claim 1 of the present invention will be described below with reference to the drawings.

1, 2, and 4 show an overcurrent protection device according to an embodiment of the present invention. FIG. 1 is a circuit diagram and FIG.
Is a sectional view, and FIG. 4 is a perspective view.

In the figure, reference numeral 30 is a first base, which is made of an insulating thermoplastic resin. 31 and 3
Reference numeral 2 denotes a pair of fixed contact plates which are partly exposed in the first base 30 and have one end protruding outside the base and are integrally formed with the first base 30. Fixed contacts 33 and 34 are fixed to the exposed portions of the pair of terminal plates 31 and 32.

Reference numeral 35 denotes a bimetal plate which is formed into a dish shape and has a heat sensitive surface 35a which is snap-actiond by temperature and which is blackened by etching. 36
And 37 are movable contacts, which are welded to the high expansion side of the bimetal plate 35. Numeral 38 is an adjusting screw, which holds the bimetal plate 35 in a reversible manner and holds the movable contact 36,
37 is fixed.

Reference numeral 39 denotes a second base which is formed of a thermosetting resin having an insulating property and has a protrusion 39a.
Reference numeral 40 denotes a spring terminal, which is a protruding portion 39a of the second base 39.
It is stored in.

Reference numeral 41 denotes a heater terminal plate, one end of which is projected to the outside of the second base 39 and the fixed contact plate 32.
And a pair of terminal plates, and having a spring property, is urged in a direction away from the fixed contact plate. Reference numeral 42 denotes a heater, one end of which is welded to the spring terminal 40 and the other end of which is welded to the heater terminal plate 41. Reference numeral 43 is a temperature detecting member made of a shape memory alloy, and the fixed contact plate 32 and one end of the heater terminal plate 41 are in contact with each other.

The operation of the overcurrent protection device configured as described above will be described below. In the figure, first, the load current is the spring terminal 40, the heater 42, the heater terminal plate 41,
Flowing through the circuit of the terminal plate 43, the fixed contact plate 32, the bimetal plate 35, and the fixed contact plate 31, the heater 42 and the first bimetal plate 35 self-heat in proportion to the magnitude of the current.

Next, when an overcurrent occurs, the current increases, the temperature of the bimetal plate 35 rises, and the heat from the heater 42 is absorbed by the bimetal plate heat sensitive surface 35a, whereby the temperature of the bimetal plate 35 rises quickly. , When the temperature exceeds the set value, it reverses to open the contact and shut off the circuit. Next, when the load is cooled and the temperature of the bimetal plate 35 becomes equal to or lower than the set value, the bimetal plate 35 reverses and returns to close the circuit again.

At this time, if the overcurrent state continues, the bimetal plate 35 repeats reversion and return, and the bimetal plate 35 is fatigue fractured to cause contact welding. Continuing to energize due to contact welding, the heat of the heater 42 is transmitted to the temperature detecting member 43 through the heater terminal plate 41, the temperature detecting member 43 made of a shape memory alloy transforms, the contact between the terminal plates is released, and the circuit is turned off. Hold on.

As described above, according to this embodiment, by providing the heat sensitive surface 35a on the bimetal plate 35, the bimetal plate 35 can be quickly heated and the reversing operation can be quickly performed.

Next, an overcurrent protection device of another embodiment will be described with reference to the drawings. Only the differences from the previous embodiment will be described.

An inorganic paint 44 is applied to a part or all of the heater 42. As described above, according to this embodiment,
By applying the inorganic paint 44 to a part or all of the heater 42, it is possible to prevent the insulation performance from deteriorating due to arcing or the like when the bimetal plate 35 is reversed to the heater 42 side.

[0024]

As described above, according to the present invention, the first base made of resin, the pair of terminal plates integrally molded with the first base and having the fixed contacts, and the heat having the pair of movable contacts at both ends are provided. A response element, a second base made of resin, a spring terminal held by the second base and connected to the outside, a heater connected to the spring terminal, and a heater terminal plate connected to the heater, An overcurrent protection device comprising a leaf spring welded to a heater terminal plate and biased away from one of the terminal plates, and a low melting point metal connecting the leaf spring and one of the terminal plates. It is possible to provide an overcurrent protection device having excellent performance by swiftly performing the reversing operation of the heat responsive element at the time of overcurrent by adopting a constitution in which the heat-sensitive surface opposed to the heater of FIG.

Further, since the inorganic coating material is applied to a part or all of the heater, it is possible to prevent the insulation performance from being deteriorated due to arcing or the like when the heat responsive element is turned to the heater side. Therefore, it is possible to provide a highly reliable overcurrent protection device.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an overcurrent protection device in an embodiment of the present invention.

FIG. 2 is a sectional view for explaining the operation of the overcurrent protection device according to the embodiment.

FIG. 3 is a cross-sectional view of a main part in another embodiment of the present invention.

FIG. 4 is a perspective view for explaining the operation of the overcurrent protection device according to the embodiment.

FIG. 5 is a side view of a conventional overcurrent protection device.

6 is a plan view of the overcurrent protection device of FIG.

[Explanation of symbols]

 30 First Base 31, 32 Fixed Contact Plate 33, 34 Fixed Contact 35 Bimetal Plate 35a Heat Sensitive Surface 36, 37 Movable Contact 38 Adjust Screw 39 Second Base 40 Spring Terminal 41 Heater Terminal Plate 42 Heater 43 Temperature Detection Member 44 Inorganic System paint

Claims (2)

[Claims] 1. A first base made of resin, and a part of the first base is exposed in the first base and one end of the first base is projected to the outside of the first base to be integrally molded with the first base. And a pair of terminal plates each having a fixed contact on the exposed portion, a thermo-responsive element formed in a dish shape and having a pair of movable contacts at both ends, a second base made of resin, and a second base on the second base. A spring terminal held and connected to the outside; a heater having one end connected to the spring terminal; a heater terminal plate connected to the other end of the heater and having one end outside the second base; Overcurrent protection consisting of a leaf spring welded to a heater terminal plate and biased so as to be normally separated from one of the pair of terminal plates, and a low melting point metal connecting the plate spring and one of the pair of terminal plates. In the device, the heater of the thermoresponsive element is paired with the heater. An overcurrent protection device characterized in that the heat-sensitive surface against which it resists is blackened. 2. A first base made of resin, and a part of the first base is exposed in the first base and one end of the first base is projected to the outside of the first base to be integrally molded with the first base. And a pair of terminal plates each having a fixed contact on the exposed portion, a thermo-responsive element formed in a dish shape and having a pair of movable contacts at both ends, a second base made of resin, and a second base on the second base. A spring terminal engaged with and connected to the outside, a heater having one end connected to the spring terminal, and a heater terminal plate connected to the other end of the heater and having one end outside the second base, An overcurrent composed of a leaf spring welded to the heater terminal plate and urged so as to be normally separated from one of the pair of terminal plates, and a low melting point metal connecting the plate spring and one of the pair of terminal plates. In the protection device, part or all of the heater is An overcurrent protection device characterized by applying mechanical paint.