JPS5849978B2 - thermal device - Google Patents

Description

[Detailed description of the invention] This invention relates to a thermal device.

Bimetal heating methods can be roughly divided into the types shown in Figures 1 to 3.

That is, FIG. 1 shows a direct heating type in which a current is directly passed through the bimetal 1 to cause it to self-heat, thereby causing it to perform a bending motion.

2 is a bimetal fixing plate, and 3 is a copper stranded wire.

Figure 2 shows a direct heating type with bimetallic HC heater wire 4 wound around it.
One end of the bimetal 1 is connected to the tip of the bimetal 1, and the bimetal 1 is heated by itself and heated by the heater wire 4 to perform a bending operation.

FIG. 3 shows an indirect heating type in which the bimetal 1 is heated by a heater 5 provided on the fixed plate 2.

These time-deflection characteristics are as shown in FIG. 4, and when these are applied to a breaker, the current-time operating characteristics are as shown in FIG.

The previous day [i-, the horizontal axis is the time t, the vertical axis is the deflection amount δ, the curve Q is the direct heating type, the curve Q2 is the indirect heating type, and the curve Q3
is of indirect heating type.

Further, in FIG. 5, the horizontal axis represents the ratio of the operating current to the rated current (■/■N), and the vertical axis represents 1'a''J(t) during operation.

The curve Ql is the direct heating type, the curve Q5 is the indirect heating type, and the curve q is the indirect heating type.

On the other hand, devices to be protected have various characteristics and are usually manufactured as appropriate based on the above three types so as to achieve the best protection coordination.

By the way, the starting characteristics (load current characteristics) of the motor are as shown in Figure 6.

In the figure, the curve Q7 indicates a blower or the like with a large starting current (large torque), and the curves Q8 to Q9 indicate those with a sequentially small torque.

If the characteristics of the thermal element are incorrectly selected for the starting characteristics of such a motor (for example, using a thermal element with operating characteristics that intersect with the starting characteristics), malfunction will occur and proper protection coordination will not be achieved.

As a result, conventional thermal elements have the disadvantage that many types of thermal elements must be manufactured depending on the characteristics of the object to be protected.

Therefore, an object of the present invention is to provide a thermal device that can produce a variety of properties with one type of product through simple operation.

An embodiment of this invention is shown in FIG.

Claims (1)

[Scope of Claims] 1. A thermal device comprising a directly heated bimetal and a time delay characteristic setting member that relatively increases the heat capacity of the bimetal by following and contacting the bending motion of the directly heated bimetal. 2. The thermal device according to claim 1, wherein the time delay characteristic setting member makes follow-up contact within a rated deflection range of the directly heated bimetal. 3. The thermal device according to claim 2, wherein the time delay characteristic setting member is a bendable leaf spring fixed to the base end side of the directly heated bimetal. 4. The thermal device according to claim 2, wherein the time delay characteristic setting member is a bimetal. 5. The thermal device according to claim 1, wherein the time delay characteristic setting member is a heat receiving plate that is supported by a spring and comes into follow-up contact with the directly heated bimetal.