JPS5843162Y2 - heat sensitive switch plug - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heat-sensitive switch plug whose contacts open and close according to changes in the temperature of an object to be measured, and relates to a heat-sensitive switch plug whose function can be easily tested after manufacturing or during use.

Conventionally, in automobile exhaust purification systems, a ceramic core rod is inserted into a heat-resistant metal outer cylinder with a bottom as a sensor to prevent overheating, and the difference in thermal expansion between the two is used to close the open end of the outer cylinder. A heat-sensitive switch plug is installed that opens and closes the contacts provided in the direction.

This type of heat-sensitive switch plug needs to be inspected as appropriate to determine whether the contact gap is appropriate after manufacturing or during use.
Because it is large, about 6 mm, it is necessary to heat the heat-sensitive switch plug in a high-temperature furnace or run the engine to raise the temperature of the exhaust purification device, or to measure the insulation resistance by applying a high voltage of around 1000 V at room temperature to cause a corona discharge. method is taken.

However, these inspection methods deteriorate the catalyst of the exhaust purification device, take time to attach and detach the heat-sensitive switch, require equipment such as an electric furnace, or damage the contact surfaces and other insulating parts due to electrical discharge. There were drawbacks such as.

The object of the present invention is to provide a heat-sensitive switch plug that allows the suitability of contacts to be tested very easily.

In this invention, a ceramic core rod is inserted into a heat-resistant metal outer cylinder that is closed at one end, and a contact point is formed between the open end of the outer cylinder and a movable terminal fixed to the core rod. In a heat-sensitive switch plug in which the contact is opened and closed by the difference in thermal expansion between the cylinder and the core rod, a cylindrical housing that encloses the contact is provided integrally with the outer cylinder, and a cylindrical housing is provided between the housing and the movable terminal at room temperature. The main point is that a gap smaller than the contact gap is formed in the contact gap.Next, the present invention will be explained based on an embodiment shown in the drawings.

Reference numeral 1 denotes a heat-resistant metal outer cylinder made by cutting a stainless steel pipe to a predetermined length, one end of which is closed with a bottom plate 11 made of a nickel-based heat-resistant alloy, and a flange 10 is fixed to the outer periphery.

2 is a hollow core rod made of heat-resistant and insulating ceramic such as alumina, silica, and Mura 41, 12 is a ceramic bearing fitted to the bottom of the outer cylinder, and 13 is the open end of the outer cylinder. The middle rod 2 is supported by a bearing 12.13 with one end in contact with the bottom plate 11, and is coaxially inserted into the outer cylinder 1. There is.

3 is a top-shaped movable terminal, and one shaft 32 is connected to the core rod 2.
The lower surface of the flanged portion 31 and the bearing 13 are fitted into the free end 22 of the
The two surfaces have a gap of 0.4 to 5 mm and form an electrical contact S1.

A and b are contact materials such as silver palladium and gold palladium that are welded to both sides of the contact S1, and the contact S1 closes when the heat receiving area A of the thermosensitive switch plug reaches a set temperature or higher.
Open when the temperature is below the set point.

4 is an electric wire having a wire mesh sheath 40 on its outer periphery; 41 is its insulating coating; 42 is a core wire; 5 is a top-shaped electric wire terminal with one shaft 50 fitted into the wire 4 and connected to the core wire 42;
is its brim.

Reference numeral 6 is attached between the flange-like part 31 of the movable terminal and the flange-like part 51 of the electric wire terminal to electrically connect the two and to connect the movable terminal 3
and a spring that urges the core rod 2 toward the bottom of the outer cylinder, and 7 is a cylindrical metal contact housing, one end of which is fitted onto the opening side of the outer cylinder 1 and brazed 7. , the end of the electric wire 4 is fitted to the other end.

8 is a metal cylinder, the lower end 81 of which is connected to the flange 3 of the movable terminal.
0.1-0.3 mm, preferably 0.1 to 0.3 mm between the upper surface of
The housing 7 has a gap S2 of 2 to 0.25 mm.
It is fitted inside.

If the gap S2 is less than 0.1 mm, contact may occur due to manufacturing errors, and if it is more than 3 mm, it will be close to the gap of the contact S1, and when inspecting the gap S2 due to corona discharge, contact S may occur.
A high voltage is required, which is not much different from that in the case of directly inspecting the contact point S1, and the effect of providing the gap S2 is lost, and discharge is likely to occur at the contact point S1.

The heat-sensitive switch plug indirectly connects the contact S1 by applying a voltage of 50 to ioo v between the electric wire 4 and the outer cylinder or the vehicle body, causing a corona discharge in the gap S2, and inspecting the suitability of the size of the gap S2. It is possible to judge the suitability of the test and the presence or absence of short circuits in other parts.

In this test method, the applied voltage can be as low as 100μ or less, so it is easy to handle, and since there is no discharge at contact S1, damage to the contact surface can be prevented.Furthermore, a heat-sensitive switch plug can be attached to the exhaust purification device. It can be inspected in its original state, requiring less effort.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention. In the diagram: 1...outer cylinder, 2...core rod, 3
...Movable terminal, SL...Contact, 7...
...Housing, S2...Gap.

Claims (1)

[Scope of utility model registration request] A ceramic core rod is inserted into a heat-resistant metal outer cylinder that is closed at one end and open at the other end, and a metal movable terminal is fixed to the end of the core rod so as to protrude from the outer cylinder. A contact point with a gap size of 0.4 to 0.6 mm is formed between the opening side end and the end surface of the outer cylinder opening side of the movable terminal fixed to the core rod, and the difference in thermal expansion between the outer cylinder and the core rod forms a contact point. In a heat-sensitive switch plug configured to open and close a contact, a cylindrical housing is provided integrally with the outer cylinder and encloses the contact, and a cylindrical housing is provided between the protrusion protruding from the inner periphery of the housing and the other end surface of the movable terminal. Contact gap '0.
1 to Q, a heat-sensitive switch plug characterized in that an axial gap of 3 mm is formed.