JPH0231995Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a spark plug used in an internal combustion engine that improves its stain resistance.

[Conventional technology]

Conventionally, when a new car is transported from the automaker to the user, carbon, water, oil, etc. tend to adhere to the surface of the insulator of the spark plug, which often makes spark discharge difficult. .

Conventionally, in order to prevent such smoldering contamination, as shown in FIG. A porous insulating layer 11 is formed, and the porous interior is impregnated with an electrically insulating oil such as silicone oil, fluorine oil, or a mixed solution of these and paraffins having good water repellency. A method has been proposed to reduce the burnout of the oil due to combustion gas and to prevent the deterioration of insulation due to adhering carbon or water as a supply source for forming the oil film 12 on the surface of the leg (practical application). Publication No. 104483 (Sho 57-104483).

[Problem that the invention attempts to solve]

However, since the porous insulating layer 11 is formed inside the pocket 13 of the housing 6 into which the combustion gas flows, prevention of burnout of the electrically insulating oil impregnated inside the insulating layer 11 is incomplete. Therefore, once the electric insulating oil is operated under especially high-speed conditions, the high temperature combustion gas causes the electrical insulating oil to exceed its heat resistance limit, seize up, and make it impossible to supply the oil to the legs 3c, resulting in an oil film 1.
It has the disadvantage that it cannot form 2.

In addition, since the insulating layer 11 is in close contact with the surface of the leg portion 3c, heat circulation becomes poor, leading to a decrease in heat value and also decreasing the flash over voltage of the insulator leg portion.

[Means for solving problems]

Therefore, the present invention solves the above-mentioned drawbacks caused by the influence of combustion gas, and in order to supply the insulator legs with the necessary amount of electrically insulating oil necessary for the staining effect, the head, body, and an insulator having legs in this order; a center electrode held on the legs of the insulator; and a center electrode fixed to the insulator so as to cover the outside of the body and legs of the insulator. A spark plug comprising a metal housing and a ground electrode provided in the housing and forming a spark gap between the housing and the center electrode, the spark plug connecting the body part and the leg part of the insulator. A seat is provided on the inner surface of the housing at a position facing the surface, and between the seat and the connecting surface, the housing is made of a porous metal material impregnated with electrically insulating oil having water repellency. Along with exposing
A technical measure is adopted in which a support member is arranged so as to be able to supply the surface of the leg of the insulator by thermal expansion.

〔Example〕

In FIGS. 1 and 2, the insulator 3 has a head portion 3a, a body portion 3b, and a leg portion 3c in this order, and the center electrode 1 is held on the leg portion 3c. A metal housing 6 is fixed to the insulator 3 so as to cover the outer surfaces of the body 3b and legs 3c of the insulator 3. A seat portion 6c is provided in the housing 6 at a position facing the tapered connecting surface 3d between the body portion 3b and the leg portion 3c of the insulator 3.

In the present invention, a porous support member 7 made of porous metal such as copper or iron is arranged between the seat portion 6c and the connection surface 3d so as to be exposed to the combustion gas as shown in the figure. be. The support member 7 is impregnated with electrically insulating oil such as silicone oil. In addition, in the figure, 4 is a center shaft, 5 is a terminal portion screwed onto the tip of the center shaft 4, 6a is a threaded portion of the housing 6, and 6b
8 is the inner surface of the housing 6, 8 is a caulking ring, 9 is a ground electrode fixed to the housing 6 so as to form a spark gap 2 with the tip of the center electrode 1, and 10 is a conductive glass layer.

By the way, when the support member 7 is heated due to the temperature during combustion, the impregnated electrically insulating oil expands and oozes out onto the surface of the porous metal, causing the insulator leg portion 3a to ooze out.
It can gradually penetrate the surface of the oil and form an oil film layer 12. Here, since the support member 7 is less exposed to combustion gas, the electrically insulating oil impregnated therein does not exceed its heat resistant temperature and is not burnt out. Therefore, each time heating is repeated, the oil gradually seeps out from inside the support member 7, making it possible to supply the oil to the surface of the leg portion 3c of the insulator 3 more sustainably than before.

Therefore, according to the present invention, the anti-fouling effect can be exhibited not only during transportation of a new car but also in the market for a long period of time.

Further, there is no influence on other performance characteristics such as heat value and flash over voltage of the leg portion 3c.

Furthermore, in terms of productivity, it can be assembled using existing equipment, and is advantageous in terms of cost compared to conventional plugs.

An experimental example of the present invention is shown below. Figure 3 shows the fouling evaluation results, and the test engine was water-cooled at 1600 c.c., 4 cycles. The test conditions were to perform a pattern of racing at a low temperature of -10℃, repeating 5 times of racing and 6 times of acceleration from 10Km/H to 20Km/H, then stop for 5 minutes, and then repeat the same pattern of operation again as one cycle. The tests were conducted after the engine had been operated for 5 minutes with the center electrode temperature at approximately 600°C, assuming drum operation during the engine inspection process at the manufacturer.

As a result, compared to the conventional spark plug B, which has a porous insulating layer formed inside the pocket of the housing and impregnated with electrically insulating oil, the insulation resistance value decreases to less than 10 MΩ after an average of 9 cycles. Spark plug A, in which the supporting member of the present invention was impregnated with electrically insulating oil, showed no decrease in insulation resistance even after 10 cycles, and was heated to 600°C and operated in the same pattern again, and was insulated after the 5th cycle on average. The resistance value was lowered and the stain life was significantly improved. Incidentally, spark plug C, which was not coated with electrically insulating oil, had 4 cycles.

In addition, Figure 4 shows the results of measuring the flash over voltage that causes sparks to fly from the center electrode to the inner surface of the housing, and Figure 5 shows the results of measuring the heat value. is advantageous.

[Effect of idea]

As described above, in the present invention, the support member 7 is exposed to combustion gas, and the exposed support member 7 is impregnated with electrical insulating oil, so that the thermal expansion of the support member 7 provides support. The electrical insulating oil can gradually seep out from the inside of the member 7, and the electrical insulating oil can be supplied to the surface of the leg portion of the insulator in a specific manner.

Furthermore, each time this supporting member is heated by combustion gas, electrical insulating oil gradually seeps out from inside the supporting member, so that a specific supply of electrical insulating oil can be achieved on the surface of the legs of the insulator. This makes it possible to exhibit the anti-fouling effect not only when transporting a new car but also in the market for a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a half-sectional view showing the main parts of the plug of the present invention, Fig. 2 is a partially broken sectional view showing the entire plug of the present invention, and Figs. 3 to 5 are characteristics used to explain the operation of the present invention. FIG. 6 is a partially cutaway sectional view showing a conventional plug. DESCRIPTION OF SYMBOLS 1... Center electrode, 2... Spark gap, 3... Insulator, 3a... Head, 3b... Body, 3c... Leg, 3d... Connection surface, 6... Housing, 7... …
Support member, 9... ground electrode.

Claims (1)

[Claims for Utility Model Registration] An insulator having a head, a body, and a leg in this order, a center electrode held on the leg of the insulator, the body of the insulator, and the leg. a metal housing fixed to the insulator so as to cover the outside of the leg; a ground electrode provided on the housing and forming a spark gap with the center electrode;
A spark plug comprising: a seat portion provided on the inner surface of the housing at a position opposite to a connection surface between the body portion and the leg portion of the insulator, and a seat portion between the seat portion and the connection surface. The insulator is made of a porous metal material impregnated with a water-repellent electric insulating oil, and is exposed to the combustion gas and receives heat from the combustion gas to cause thermal expansion of the insulator. A spark plug comprising a support member arranged to supply the electrically insulating oil to the surface of the leg.