JPS5864723A - Temperature protecting switch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention detects abnormal temperature rises in electronic equipment, etc., and immediately shuts off the circuit when the temperature of the equipment or parts rises above a preset temperature to protect the equipment, circuits, etc. related to temperature switches.

Shape memory alloys are made by forming a shape in a high-temperature matrix,
It has an extremely unique property of returning to its formed shape through martensitic transformation when the temperature is lowered. Therefore, the martensitic state transforms to the parent phase, and the contacts open and close at around room temperature. alloy composition to match the temperature
By using a shape memory alloy manufactured under different processing conditions as a temperature-sensitive element, it is possible to manufacture a temperature-sensitive spring whose shape can be deformed by changes in temperature around room temperature.

In addition, the shape memory alloy has a tensile strength value for the same amount of strain when it is in the high-temperature matrix state and when it is in the low-temperature martensitic transformation state. Approximately 3 times larger than Therefore, by utilizing these characteristics together, it is possible to construct a switch of this type that has a reliable temperature response and is inexpensive.

In view of this, the main object of the present invention is to utilize the property of shape memory alloys to cause deviations in shape due to changes in ambient temperature, and to propose a temperature protection switch whose structure operates reliably.

An embodiment of the present invention will be described in detail below with reference to the drawings.

Fig. 1 is a plan view of a temperature protection switch showing an example of the present invention, and Figs. 2 and 3 are the lines ■-■ and m-III in Fig. 1.
FIG. All of them are in a pending state. Further, FIG. 4 shows the operating state of the example shown in FIG. 2, and shows the open state of the switch.

1 indicates a temperature-sensitive spring, which is made of a shape memory alloy.

When the temperature rises and the shape memory alloy returns to its parent phase structure,
Since it has the property of returning to the preformed shape in the matrix state, when the temperature rises and the matrix state is in the matrix state, it is formed into a bent shape as shown in Figure 4. I'll keep it. Therefore, when the structure of the shape memory alloy changes from martensitic transformation to the matrix, the first and fourth temperature sensitive elements that were in close contact with the temperature sensitive element 20
As shown in the figure, it returns to its original molded shape. In FIGS. 1 to 3, reference numeral 2 denotes a hook body, which engages with the temperature-sensitive barb 1 at a temperature that maintains martensitic transformation, and is preferably made of a spring material. In addition, in shape memory alloys, there is a difference in tensile strength for the same amount of strain between the martensitic transformation and the matrix state, and the tensile strength in the matrix state is about three times that of the martensitic state. When the temperature of the temperature-sensitive spring 1 rises and returns to the matrix structure, the tensile strength of the temperature-sensitive spring 1 increases, and the connection with the hook body 2 is suddenly released, returning to the original shape as shown in FIG. Configured to return. Incidentally, the tip of the temperature-sensitive spring 1 and the tip of the hook body 2 are formed into a sharp point so that they can be easily released from each other.

Since the movable contact 4a is fixed to the temperature-sensitive spring 1 via the insulating plate 10, the fixed contact 4b changes depending on the deformation of the temperature-sensing spring 1.
Contact and separation. The movable contact 4a is a lead wire 9 that is electrically connected to one terminal 7a provided on the base 12.
connected by.

On the other hand, the fixed contact 4b is connected to the other terminal 7b provided on the base 12.
electrically connected to. Reference numeral 8 indicates a conductor for connecting the fixed contact 4b and the terminal 7b. In addition, the hook body 2 has a screw 6
However, in order to adjust the engagement force with the temperature-sensitive spring 1, the screw mounting hole of the hook body 2 is made into a long hole or an entry hole, so that it can be mounted in a sliding manner. It is formed.

The temperature protection switch configured as described above is screwed to a heat-generating portion of the temperature sensing element 20, for example, an electronic device, using the mounting screw hole 11. In addition, 5.

A pusher is shown for reattaching the temperature-sensitive bar 1 which has been bent in response to the hook body 2.

Next, the operation of the switch of the present invention will be explained.

The temperature-sensitive spring 1 made of a shape memory alloy is preformed into a shape as shown in FIG. 4 at the temperature of the matrix state, so that the shape in the matrix state is memorized. Even if the temperature-sensitive spring 1 reaches the state of martensitic transformation, which is lower than the temperature of the matrix in which it was molded, it retains the shape it had when it was molded in the matrix as long as no external force is applied. Since the force required to deform the warm spring 1 is approximately 1/3 of that in the matrix, the temperature sensitive spring 1 is
By pressing , it is easily deformed and returns to the shape shown in FIG. The thermosensing spring 1 and the hook body 2 are held in close contact with the thermosensor 20.

By connecting an electric circuit to the terminals 7a and 7b, the circuit can be opened by operating the temperature-sensitive spring 1. That is, as shown in FIGS. 1 to 3, the contacts 4a,
4b is in the closed state, when the temperature of the temperature-sensitive spring 1 approaches the parent phase transformation temperature due to an abnormal temperature rise, the tensile strength of the temperature-sensitive spring 1 increases, and the temperature-sensitive spring 1 suddenly resists the retention with the hook body 2. deformed,
Instantly opens the contacts. Therefore, when the equipment reaches an abnormal temperature state, the circuit can be cut off to protect the equipment.

When the abnormal temperature is eliminated and the temperature of the temperature-sensitive spring 1 is also lowered to undergo martensitic transformation, the pusher 5 can be pressed again to maintain the state of engagement between the magnetic temperature-sensitive spring 1 and the hook body 2.

As described above, the present invention includes a temperature-sensitive spring made of a shape memory alloy, a hook body releasably engaged with the temperature-sensing spring, and the temperature-sensitive spring is in contact with the temperature-sensitive body, Since the temperature-sensing spring operates and disengages from the hook body to open and close the contact, the circuit in the electronic device can be prevented from being damaged due to abnormal temperature rise of the temperature-sensing body. Since the circuit can be cut off, it has the effect of temperature protection.

Moreover, since the temperature-sensitive spring is in direct contact with the temperature-sensitive body, the temperature-sensing reaction speed is fast, and it can also contribute to miniaturization of the temperature-sensitive spring. In addition, the hook body 2 can be slid to adjust the amount of engagement with the temperature-sensitive spring 1, and the tensile strength of the temperature-sensitive spring 1 at its parent phase and the operating temperature of the deflection force of the hook body 2 can be arbitrarily selected. It can be done easily.

Furthermore, the tip of the temperature-sensing spring 1 is formed with a step by cutting off the side facing the temperature-sensing body 20 in order to facilitate engagement with the tip of the hook body 2. The spring 1 and the hook body 2 can be easily engaged.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an example of the present invention, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line DI--■ in FIG.
FIG. 4 is a diagram for explaining the operating state of the switch of the present invention. 1... Temperature-sensitive spring, 2... Hook body, 4a, 4b...
・Husband contact point. Agent Anatomist Takashi Akiyama

Claims (1)

[Claims] It is composed of a temperature-sensitive spring made of a shape memory alloy, and a hook body that is releasably engaged with the temperature-sensing spring, and the temperature-sensitive spring is in contact with the temperature-sensitive body, and the temperature-sensitive spring is actuated to cause the above-mentioned Temperature protection switch 0 characterized in that the contact opens and closes when the connection with the hook body is released.