JPS5928191Y2 - heating tap - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a heating plug used as a starting assist device for a diesel engine.

The heating plug used as a starting aid for modern diesel engines is made by embedding a printed heater as a heat generating element in a heat generating part made of ceramic material, firing it, and screwing the heat generating part into the 7 cylinder head of the engine. It is configured to be inserted and fitted into the main body that is attached by.

Although the heating plug constructed in this manner can generate heat in a short period of time, the temperature gradient in the heat generating part becomes steep when the heat is generated, which has a negative effect on the durability of the heat generating part.

It is clear from the temperature characteristic curve of the heat generating part shown in FIG. 2 that this effect is particularly large near the connection part of the heat generating part with the main body.

That is, Fig. 2 shows the temperature characteristics of the entire heat generating group when the heating setting temperature near the tip a of the heat generating part reaches 900°C, for example, and the broken line N is the temperature characteristic of the heat generating part of the conventional heating plug.
It can be seen that the temperature gradient near the connection part C between the main body 1 and the heat generating part 2 is the steepest.

A part with such a significant temperature gradient generates thermal stress, which has the drawback of being easily broken due to repeated stress.

This invention was devised to improve the shortcomings of conventional heating plugs as described above, and maintains the rapid heating characteristics of heating plugs with heat-generating parts made of ceramic material, while improving its durability and reliability. To provide a heating tap with improved

Examples thereof will be described below with reference to the drawings.

Referring to FIG. 1, reference numeral 1 denotes the main body of a heating plug used as a starting aid for a diesel engine. A large diameter rear end side 21 of a heat generating section 2 made of a fired ceramic material with a printed heater 5 as a heat generating element embedded therein is inserted into the side and joined by brazing or the like.

The printed heater 5 has a -3451 end connected to the main body 1, and the other end 52 connected to the pin 4 via a conductive member 6 such as a conductive wire.

In addition, a heat insulating member 7 made of a ceramic material or the like covers a part of the outer periphery of the heat generating part 2 extending from the connection part C with the main body 1 having the most significant temperature gradient to a suitable length, and the front end of the main body 1 What is the diameter of 11? Coated with a thickness equal to or less than the diameter.

Further, at the rear end of the pin 4, there is an insulating packing 8, a positioning nut 9, a connector 10 connected to the electrode, a washer 30, and a connector mounting nut 40, similar to the conventional heating plug.
are installed respectively.

Further, a metal backing 70 made of copper or the like is disposed between the holding member 3 and the heat generating portion 2 for cushioning purposes.

In a diesel engine equipped with a heating plug configured as described above, when the heating plug is energized to help start the engine, as shown in the temperature characteristic curve in Figure 2, the area near the tip a of the heat generating part 2 immediately heats up to the set temperature. While the temperature reaches 900°C, near the connection point C with the main body 1 where the temperature gradient is the most significant, the temperature gradient becomes as indicated by the solid line M in FIG. becomes smaller, and the entire heat generating part has the highest temperature (9) near the tip a.
00° C.) to the rear end d of the heat generating portion.

Therefore, the thermal stress generated in the temperature gradient region of the heat generating portion is also reduced, and thermal damage caused by repeated thermal stress is also prevented.

In this way, according to the present invention, damage due to thermal stress of the heat generating part made of ceramic material is prevented, so it is possible to provide a heating plug that maintains its rapid heating properties and has improved durability and reliability. .

In the above embodiment, the covering heat insulating member 7 is the heat generating part 2.
Although it is constructed as a separate member from the heat generating part 2, if it is made of the same material as the heat generating part 2, it is also possible to integrally mold it with the ceramic material of the heat generating part 2.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a temperature characteristic curve diagram of a heat generating portion in the same embodiment. DESCRIPTION OF SYMBOLS 1... Body of heating plug, 2... Heat generating part, 3... Insulation holding member, 4... Holding pin, 5... Print heater, 7... Heat insulating member.

Claims (1)

[Scope of utility model registration request] In a heating plug constructed by inserting and joining a rear end side of a heat generating part made of a ceramic material with a heat generating element embedded in the main body, a part of the outer periphery of the heat generating part connected to the front end of the main body is covered with a heat insulating member. A heating faucet characterized by: