JPH0982200A - Thermal overload relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the performance of an indirectly heated thermal overload relay in transferring heat from a heater to a bimetal. SOLUTION: A heat-transfer plate 8 is provided which bridges a part of the portion between a heater 1 and a bimetal 6 placed parallelly to the heater with a gap between them. The heat of the heater 1 is therefore imparted to the bimetal 6 by heat transfer via the gap and also by heat conduction through the plate 8, resulting in enhanced heat-transfer performance and the amount and speed of curving of the bimetal 6 are increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal overload relay (hereinafter referred to as a thermal relay) which bends a bimetal by heat generation of a heater through which an electric current flows to switch contacts, and particularly to an indirectly heated type relay. The present invention relates to a heat element of a thermal relay.

[0002]

2. Description of the Related Art A bimetal type thermal relay has a winding type in which a heater is wound around a bimetal (for example, an actual flat type
7249), and an indirect heating type in which a heater and a bimetal are arranged in parallel with a gap. While the wire-wound type has excellent heat transfer efficiency, it is difficult to increase the current carrying capacity of the heater that can be wound around the bimetal, so it is limited to a small size, and the indirectly heated type is used for rated currents of 30 A or more, for example. 7 to 9 show one phase portion of a heat element portion in a conventional indirectly heated thermal relay, FIG. 7 is a side view, FIG. 8 is a bottom view thereof, and FIG. 9 is a perspective view of essential parts. In these drawings, one end of a strip-shaped heater 1 is connected to a U-shaped power source side terminal 3 via a connecting rod 2 joined by resistance welding or the like, and the other end is also connected to the connecting rod 4 similarly.
Is connected to the load-side terminal 5 having a flat plate shape.

The power supply side terminal 3 and the load side terminal 5 have screw holes 3a and 5a, respectively, and are fixed by being fitted into a mold case (not shown). A bimetal 6 is arranged in parallel with the heater 1 with a gap therebetween, and the bimetal 6 is fixed to the mold case via a support metal fitting 7 joined to one end by resistance welding or the like. In the heat element portion shown in the figure, the current path is formed in the order of the power source side terminal 3, the connecting rod 2, the heater 1, the connecting rod 4, and the load side terminal 5. When heat is transferred from the heater 1 that has generated heat due to the current flowing through this current path to the bimetal 6 via the air layer, the temperature of the bimetal 6 that has risen due to this heat is curved and the bimetal 6 contacts through a transfer plate (not shown). The reversing mechanism is activated to switch the contact.

10 to 12 show another conventional heat element portion. FIG. 10 is a side view, FIG. 11 is a bottom view of the same, and FIG. 12 is a perspective view of a main part. This thermal relay is different from the conventional example shown in FIGS. 7 to 9 in that the load side terminal 5 and the support metal 7 are formed as one component, and the heater 1 is supported at one end together with the bimetal 6 by resistance welding or the like. Is that the connecting rod 4 is omitted by being joined to. Therefore, the current path is in the order of the power source side terminal 3 → the connecting rod 2 → the heater 1 → the bimetal 6 → the load side terminal 5. In this case, bimetal 6
In addition to the heat transfer from the heater 1 through the air layer, it is heated and curved by the heat conduction at the joint point and its own slight heat generation.

[0005]

By the way, the operating characteristics of the bimetal type thermal relay are that the bimetal has a sufficient bending amount even under an overload in the vicinity of the rated current, and a large bending amount occurs under an overload of several times the rated current. Speed is required. However, in the conventional example as shown in FIGS. 7 to 9, the ratio of the amount of heat received by the bimetal 6 via the air layer to the total amount of heat generated by the heater 1 is small, and the large amount of bending and the bending speed of the bimetal 6 are large. Was difficult to achieve. Further, the conventional example as shown in FIGS. 10 to 12 is relatively advantageous in terms of heat transfer surface, but the bimetal is easily displaced due to the tightening force of the terminal screw against the load side terminal 5, and the operation characteristics change. There was a problem of danger. Therefore, an object of the present invention is to improve the heat transfer performance from the heater to the bimetal in the indirectly heated type thermal relay to obtain a large bending amount and bending speed of the bimetal.

[0006]

In order to solve the above-mentioned problems, the present invention has a strip-shaped heater whose both ends are respectively connected to terminals on a power source side and a load side, and which generates heat by a current flowing between the terminals. In the thermal dynamic overload relay, the heater and the bimetal are arranged in parallel with the heater via an air gap and curved by receiving heat from the heater, and the heater and the bimetal are partially bridged by a heat conductive plate material. It shall be.
According to such a means, the heat of the heater is given to the bimetal by heat conduction through the plate material in addition to heat conduction through the air layer, so that the heat transfer performance is improved accordingly.

Although a slight restraining force is generated in the bimetal by providing the above plate material, it is possible to make the plate material a flexible thin plate and to have slack, so that the bending of the bimetal is hardly affected. . In this case, it is effective to increase the amount of conductive heat by constructing a heat conductive plate material by laminating a plurality of thin plates. Further, by providing the heat conductive plate material at two positions along the longitudinal direction of the heater and the bimetal, a current path passing through the bimetal can be formed between them and the temperature rise can be promoted by heat generation of the bimetal itself. By adjusting the distance between the plate materials, it is possible to adjust the heat generation amount and change the operating characteristics of the thermal relay.

[0008]

1 is a perspective view of a heat element portion showing an embodiment of the present invention, FIG. 2 is a side view of FIG. 1, and FIG. 3 is a bottom view thereof. In these figures, the difference from the conventional example of FIGS. 7 to 9 is that the heater 1 and the bimetal 6 are partially bridged by a heat conductive plate member 8. The heat-conducting plate member 8 is formed by bending a copper thin plate having a thickness of 0.1 mm in a U-shape, and is joined to the heater 1 and the bimetal 6 by means of resistance welding or the like at both legs thereof. According to this structure, the heat from the heater 1 is transferred to the plate member 8 in addition to the heat transfer through the air layer in the void.
It is also given to the bimetal 6 by heat conduction from, and the bending amount and bending speed thereof are improved.

In this case, the plate member 8 is provided with an appropriate slack and is sufficiently flexible as compared with the thermal deformation force of the bimetal 6, so that the plate member 8 hardly obstructs the curve of the bimetal 6. However, since the amount of bending of the bimetal 6 increases as it gets closer to the tip, the mounting position of the plate material 8 should be closer to the joint end of the bimetal 6 with the supporting metal fitting 7. Can easily escape toward the support metal fitting 7. Therefore, as a mounting position of the plate member 8, a position separated from the above-mentioned joint end by about 1/4 of the length of the bimetal 6 is suitable.

FIG. 4 is a perspective view showing an embodiment in which the plate member 8 is composed of a plurality of thin plates. That is, the plate material 8 has a thickness of 0.
It is constructed by laminating several 1 mm thick copper thin plates, and each thin plate is integrated by being joined to each other at a point 8a by resistance welding or the like. According to such a configuration, the heat transfer cross-sectional area of the plate member 8 increases, and the heat transfer efficiency improves accordingly.

FIG. 5 is a side view showing an embodiment in which the plate member 8 is provided at two locations along the longitudinal direction, and FIG. 6 is a bottom view thereof. In this case, the electric current goes through the heater 1 between the left and right plate materials 8 and also the plate material 8 (right) → bimetal 6 → plate material 8
Go through the route (left). Therefore, the temperature of the bimetal 6 rises not only by the heat received from the heater 1 but also by the heat generated by itself in the above path, and the bending amount and the bending speed are further improved. Moreover, since the amount of heat generated by the bimetal 6 itself changes depending on the distance L between the left and right plate members 8, the operating characteristics of the thermal relay can be changed by adjusting the distance L.

[0012]

According to the present invention, in addition to the heat transfer through the air layer, the heat of the heater can be applied to the bimetal by the heat transfer through the heat conductive plate material.
Even in an indirectly heated thermal relay, a sufficiently large bimetal bending amount and bending speed can be realized.
In that case, it is effective to increase the amount of heat conduction by stacking a plurality of thin plates, and if the plates are provided at two locations along the longitudinal direction of the heater and the bimetal, the bimetal itself generates heat. Moreover, it is possible to change the operating characteristics of the thermal relay by adjusting the distance between the plate materials.

[Brief description of drawings]

FIG. 1 is a perspective view of a heat element portion showing an embodiment of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is a bottom view of FIG.

FIG. 4 is a perspective view showing an embodiment of a plate member configured by laminating a plurality of thin plates.

FIG. 5 is a side view of a heat element portion showing an embodiment of the present invention in which plate members are provided at two places.

FIG. 6 is a bottom view of FIG.

FIG. 7 is a side view of a heat element portion showing a conventional example.

FIG. 8 is a bottom view of FIG. 7;

9 is a perspective view of an essential part of FIG.

FIG. 10 is a side view of a heat element portion showing another conventional example.

11 is a bottom view of FIG. 10.

FIG. 12 is a perspective view of a main part of FIG. 11.

[Explanation of symbols]

 1 Heater 2 Connection rod 3 Power supply side terminal 4 Connection rod 5 Load side terminal 6 Bimetal 7 Support metal fittings 8 Heat transfer plate

Claims (3)

[Claims] 1. A strip-shaped heater, both ends of which are respectively connected to a power source side terminal and a load side terminal and generates heat by an electric current flowing between the terminals, and the heater is arranged in parallel with this heater via a gap, A thermal overload relay including a bimetal that receives and curves, wherein the heater and the bimetal are partially bridged by a heat conductive plate material. 2. The thermal overload relay according to claim 1, wherein the heat conductive plate material is formed by laminating a plurality of thin plates. 3. The thermal overload relay according to claim 1 or 2, wherein heat conductive plate members are provided at two positions along the longitudinal direction of the heater and the bimetal.