JPS5827465Y2 - heat sensitive switch - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heat-sensitive switch that opens and closes contacts in response to changes in the temperature of an object to be measured.

Exhaust purification devices for internal combustion engines function as sensors to prevent overheating by inserting a ceramic hollow pipe-shaped core rod deeply into a heat-resistant metal outer cylinder with one end closed, and a spring interposed between the outer cylinder and the outer cylinder. A heat-sensitive switch that is held in place and that opens and closes contacts provided near the open end of its outer cylinder using a difference in thermal expansion can be advantageously used.

This type of heat-sensitive switch is used by inserting a heat-receiving part into the exhaust purification device, so the tip part in particular becomes high temperature, and if used for a long period of time, oxides (scale) will form on the metal part and the opening/closing temperature of the contact will change. There is a drawback that it is easy to do.

It is an object of the present invention to provide a heat-sensitive switch that eliminates the drawbacks of the present invention and can maintain a set contact opening/closing temperature for a long period of time.

In this invention, a hollow pipe-shaped ceramic core rod is inserted into a heat-resistant metal outer cylinder whose one end is closed with a bottom plate, and is held down by a spring, and the open end of the outer cylinder is In a heat-sensitive switch that opens and closes contacts provided nearby, the bottom plate is made of a nickel-based heat-resistant alloy, and a bearing made of ceramic or nickel-based heat-resistant alloy is fitted inside the outer cylinder to support the core rod. This is based on what was supported.

In the present invention, a nickel-based heat-resistant alloy refers to an alloy containing nickel, such as Inconel, Hastelloy, and Nimonic, which has oxidation resistance equivalent to or higher than that of Inconel.

Next, the present invention will be explained based on the embodiment shown in the drawings.

Figure 1 shows an embodiment of the present invention, where 1 is an outer cylinder formed by cutting a stainless steel pipe to a predetermined length, and 11 is a bottom plate made of a nickel-based heat-resistant alloy that closes the lower end of the outer cylinder. It is soldered.

2 is a hollow core rod made of heat-resistant and insulating ceramic such as alumina, silica, and mullite;
1 is inserted into the outer cylinder 1 while being in contact with the bottom plate 11.

Reference numeral 12 denotes a bearing made of a nickel-based heat-resistant alloy or ceramic, which is fitted to the bottom of the outer cylinder, supports the lower end of the core rod, and prevents the core rod from wobbling.

13 is a stainless steel bearing fitted to the open end of the outer cylinder 1; 3 is one shaft 32 fitted to the free end 22 of the core rod 2; the lower surface of the flange 31 is connected to the upper surface of the bearing 13 and the electrical contact S a and b are contact materials such as silver-palladium alloy or gold-palladium alloy welded to the contact surface of the contact S, and 4 is a cylindrical iron contact housing, one end of which is connected to the outer cylinder. is fitted onto the side of the opening and fixed by brazing 41,
An electric wire 42 is inserted and fixed to the other end.

Reference numeral 5 denotes a top-shaped electric wire terminal with one shaft 51 connected to the core wire of the electric wire 42, 52 denotes its collar, and 6 is attached between the collar 31 of the movable terminal and the collar 52 of the wire terminal, and the movable terminal 3 and a spring that presses the middle rod 2 toward the bottom of the outer cylinder and electrically connects the two.

This heat-sensitive switch is used by inserting the lower part of the metal ring 10 fitted into the outer cylinder into the exhaust gas purification device. Since it is made of a nickel-based heat-resistant alloy or ceramic, which has excellent heat resistance, the generation of oxides is prevented.

Therefore, the distance between the contacts S is prevented from changing over time due to the oxide, and the opening/closing temperature of the contacts is prevented from deviating from the set value, resulting in excellent durability as an overheat prevention sensor.

Since the core rod 2 is hollow, the temperature distribution in the radial direction of the cross section is uniform, so the thermal shock is small and it is difficult to break, and since it is lightweight, the core rod is prevented from swinging.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an embodiment of the present invention. In the diagram: 1...Outer cylinder, 11...Bottom plate, 1
2... Bearing, 2... Core rod.

Claims (1)

[Scope of utility model registration request] A hollow pipe-shaped ceramic core rod is inserted inside a heat-resistant metal outer cylinder whose one end is closed with a bottom plate, and is held down with a spring.
In a heat-sensitive switch that uses the difference in thermal expansion between the outer cylinder and the core rod to open and close contacts provided near the open end of the outer cylinder, the bottom plate is made of a nickel-based heat-resistant alloy, and the inside of the outer cylinder is made of a heat-resistant alloy. A heat-sensitive switch characterized by supporting a core rod by fitting a bearing made of ceramic or nickel-based heat-resistant alloy.