JPH0430392Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an overload protection device for a hermetic compressor, and in particular, increases the melting point of the insulator of the heater that thermally deforms bimetal, and lowers the heating temperature of the heater by increasing the temperature of the insulator. The present invention relates to an overload protection device for a hermetic compressor that can be set to a temperature below the heat deformation temperature of the body.

[Technical background of the invention and its problems] Generally, hermetic compressors employed in refrigeration equipment, etc. are equipped with an overload relay as a protection device in the event of overload. This overload relay is, for example, the seventh
A configuration as shown in FIG. 8 and FIG. 8 is adopted.

As shown in the figure, a fixed contact 2 is provided on a plate 1, and a movable contact 4 is provided in an upper part of a metal container 3 on the plate 1.

These contacts 2 and 4 are connected by a bimetal 5,
This bimetal 5 is designed to thermally deform when the compressor is overloaded and cut off the current to the motor.

In order to thermally deform the bimetal 5, a heater 6 is provided on the outer periphery of the metal container 3.
As shown in FIG. 9, this heater 6 has an insulator 6b made of PFA resin (perfluoroalkoxide) extruded on a nichrome iron wire 6a.
It is constructed by covering.

However, in the conventional heater 6, the insulator 6b
While the melting point of the PFA resin that forms the PFA resin is 302 to 310°C, the temperature rise of the heater 6 exceeds its continuous use limit temperature of 260°C and reaches over 300°C.
There was a problem that the bent portion 7 of the heater 6 was thermally deformed and melted.

Therefore, there was a problem in which the temperature rise of the heater 6 had to be suppressed.

[Purpose of the invention] The present invention was created to effectively solve the above-mentioned problems.

The purpose of this invention is to make it possible to expand the range of use of the heater without suppressing its temperature rise.
An object of the present invention is to provide an overload protection device that can prevent an insulator of a heater from melting.

[Summary of the invention] This invention involves installing a heater made of a hot wire coated with an insulating layer around the outer periphery of the container in order to thermally deform the bimetal that connects the fixed contact on the plate and the movable contact in the container. In the overload protection device,
The insulating layer of the heater includes a first insulating layer formed by winding a baking tape made of a synthetic resin with excellent heat resistance along the longitudinal direction around the outer periphery of the hot wire;
A second layer formed by winding raw tape around the outer periphery of the coating layer of
The melting point of the insulator is raised to increase its heat resistance.

[Embodiment of the invention] An embodiment of the invention will be described below in detail with reference to the accompanying drawings.

FIG. 6 shows a basic circuit diagram of the protection device of the present invention, in which a heater 8 and a bimetal 5 are connected in series.

Specifically, as shown in FIGS. 1, 2, and 3, the fixed contact 2 on the plate 1 and the plate 1
A movable contact 4 in a metal container 3, which is spot welded onto the top, is connected to each other by a bimetal 5.

In order to thermally deform the bimetal 5, a heater 8 is provided around the metal container 3.

In particular, in the present invention, the heater 8 is composed of a plate-shaped hot wire 9 and an insulator 10 surrounding and covering the hot wire 9.

The hot wire 9 is formed into a plate shape and is provided so as to be wound around the outer periphery of the metal container 3.

An insulator 10 covering the hot wire 9 is composed of a baking tape 10a and a raw tape 10b.

The baking tape 10a in this embodiment is made of PTFE resin (polytetrafluoroethylene) having a melting point of 327°C, and is wound around the outer periphery of the hot wire 9 in the longitudinal direction, as shown in FIGS. 4 and 5. It is turned to cover this. Further, in order to fix the baking tape 10a wound around the plate-shaped hot wire 9, a raw tape 10b is wrapped around the outer circumference of the baking tape 10a, as shown in FIG.

In this way, the present invention attaches the PTFE resin baking tape 1 that forms the substantial insulator 10 to the plate-shaped hot wire 9.
By winding and covering the baking tape 10a, the viscosity at high temperatures in the fiber direction of the baking tape 10a can be increased, and the range of temperature resistance of the insulator 10 can be expanded.

According to the present invention, it is possible to raise the continuous use limit temperature of the insulator 10 to 50 to 60 degrees Celsius compared to the conventional one, and it is possible to prevent the bent portion 7 of the heater 8 from being thermally deformed and melted.

Furthermore, since the firing tape 10a is wound with tape, it has elasticity, and this elasticity allows it to absorb the difference in thermal expansion between it and the hot wire 9.
Originally, PTFE resin has the disadvantage of being hard and brittle, so when an insulator is formed by normal pressure treatment, it cannot absorb the difference in thermal expansion between the insulator and the hot wire.
Insulators may peel or crack due to repeated thermal stress. However, if the tape 10a is used as in the present invention, the difference in thermal expansion can be absorbed by expanding and contracting using its elasticity, so the thermal stress repeatedly generated in the insulator can be alleviated, and peeling and crack damage can be prevented.

In addition, by further wrapping the raw tape 10b around the outer circumference of the baking tape 10a to cover it, the hot wire 9
It is possible to eliminate looseness between the tape 10a and the baking tape 10a. Furthermore, due to this, it is possible to protect the hard and brittle baking tape 10a.

Furthermore, by forming the hot wire 9 into a plate shape, its capacity is increased and the hot wire 9 will not be fused due to overcurrent.

In addition to Teflon PTFE forming the baking tape 10a, a material with a high melting point such as polyimide film may be used.

[Effects of the invention] In summary, according to the invention, the first insulating layer made of a synthetic resin baking tape with excellent heat resistance is provided around the outer periphery of the hot wire, so that the heat resistance temperature of the insulator can be lowered. It is possible to significantly increase the heat resistance and prevent melting of the insulator. Moreover, by expanding and contracting using the elasticity of this first insulating layer, it is possible to absorb the difference in thermal expansion between the first insulating layer and the hot wire, and to alleviate the thermal stress that repeatedly occurs.
It is also possible to prevent peeling and crack damage caused by this thermal stress.

Further, since a second insulating layer formed by further winding raw tape is provided on the outer periphery of the first coating layer, it is possible to eliminate loosening between the hot wire and the insulator.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the main parts of an embodiment of the present invention, Fig. 2 is a plan view of Fig. 1, Fig. 3 is a side sectional view of Fig. 1, and Fig. 4 is a plan view showing the heater. , FIG. 5 is a sectional view taken along the line -- in FIG. 4, FIG. 6 is a basic circuit diagram of the protective device of the present invention, FIG. 7 is a plan view showing a conventional protective device, and FIG. 8 is a cross-sectional view of FIG. The schematic sectional view and FIG. 9 are plan views showing a conventional heater. In the figure, 1 is a plate, 2 is a fixed contact, 3 is a metal container, 4 is a movable contact, 5 is a bimetal, 8 is a heater, 9 is a hot wire, 10 is an insulator, 10a is a baking tape, and 10b is a raw tape. .

Claims (1)

[Claims for Utility Model Registration] (1) A heater made of a hot wire coated with an insulating layer is wound around the outer periphery of the container in order to thermally deform the bimetal connecting the fixed contact on the plate and the movable contact in the container. In the overload protection device installed by turning,
The heater includes a first insulating layer formed by winding a baking tape made of a synthetic resin with excellent heat resistance along the longitudinal direction of the hot wire, and an insulating layer formed on the outer circumference of the first coating layer. An overload protection device comprising: a second insulating layer formed by winding a tape. (2) The overload protection device according to claim 1, wherein the firing tape is molded from PTFE resin (polytetrafluoroethylene). (3) Claim 1 of the above utility model registration, in which the above baking tape is molded from polyimide film.
Overload protection device as described in section.