JPS60193278A - Ignition plug - 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 relates to a spark plug that can be used in a wide temperature range from low engine speeds to high engine speeds, and particularly relates to the structure of its center electrode.

When the engine rotates at low speed, the temperature of the plug ignition part drops, so the surface of the leg of the insulator is easily contaminated with carbide, etc., which causes a problem of lower insulation resistance and impeded ignition performance). In order to prevent this, if the structure is such that a gap is simply provided between the inner cavity and the center electrode to raise the temperature of the insulator leg even at low temperatures, the temperature will rise too high during high speed rotation and cause premature ignition. The problem was that it reduced engine output.

Various proposals have been made to improve the problems that conventional spark plugs have, but a particularly effective prior art example is a spark plug with a center electrode structure as shown in FIG. ing. (Japanese Patent Publication No. 49-8652) As shown in the figure, this ignition book consists of a mantle 1a in which the center electrode 1 has a bottomed inner cavity, a core body 1b that is slidably inserted into the inner cavity 1a, and a mantle. A control chamber 3 is provided at the rear end of 1a, which is divided vertically into a negative pressure chamber 3a and a positive pressure chamber 3b by a diaphragm 2, and the negative pressure chamber 3a communicates with an intake pipe (not shown) of the engine. The conduit 3a-8 is also connected to the positive pressure chamber 3b.
is provided with a small hole 3b-1 that communicates with the atmosphere, and the rear end of the core body 1b of the center electrode 1 is fixed to the diaphragm 2 and has a structure that interlocks therewith, so that negative pressure can be prevented during low speed rotation. When the temperature is large, the core body 1b of the center electrode 1 is sucked upward, and a gap G is formed at the tip of the inner cavity of the mantle 1a, reducing heat loss and increasing the temperature of the insulator legs, improving stain resistance. When the negative pressure during high-speed rotation is small, there is no difference with the atmosphere, and the diaphragm 2 operates as shown by the dotted line in the figure to slide the core 1b of the center electrode 1 toward the tip, closing the gap G and closing the gap G between the insulator legs. It has the feature of improving the heat dissipation of No. 4 and preventing the occurrence of early ignition.

However, although the above-mentioned conventional spark plug is effective in expanding the operating temperature range, the conduit 3a from the engine intake pipe
The piping to -8 and other ancillary structures become complicated, which causes problems such as extremely troublesome installation and removal of the spark plug.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a spark plug that is simple in structure, has thermal characteristics suitable for operating conditions, and can be used over a wide temperature range.

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

FIGS. 2 and 3 are longitudinal cross-sections of main parts I (reeds) showing the structure of the center electrode at the tip of the insulator in one embodiment of the spark plug of the present invention.
The figures show the conditions at high temperatures.

As shown in the figure, the center electrode 11 held in the shaft hole of the insulator 10 of the ignition plug of the present invention is made of N1 or its alloy.
A core body 11-3 made of a thermally conductive metal such as O or an alloy thereof is slidably inserted into the inner cavity, and the bottom of the tip of the inner cavity of the mantle 11-1 and the core body 11-8 Crotch seat 11-1 of the enlarged diameter part inner cavity between and on the rear end side
& and the enlarged diameter flange 1l--a of the core body 11-2, there is a gap G1. G, are formed in the axial direction, and at the rear end of the enlarged diameter part of the mantle 11-1, a fixing member 13 is sealed and fixed to the inner cavity of the insulator 10 with a glass sealing material 12 in contact with the peripheral end surface thereof. For example, Ti--Ni is disposed between the fixing member 13 and the rear end surface of the enlarged diameter part of the core body 11-2 in the inner cavity of the enlarged diameter part of the mantle 11-1.

N1-Aj', ○u-AI! -Ni, 0u-Zn
A shape memory alloy member 14 having a predetermined shape such as
The tip side end surface of the fixing member 13 and the core body 11 of the center electrode 11
Recesses 1 provided at the center of the rear end surface of the enlarged diameter part of -0
It has a structure in which it is fitted and fixed to 3a*1l-zb.

The shape memory alloy member 14 described above presses and slides the center electrode 11 toward the tip side when the temperature is high, so that the gaps G8 and G,
An alloy member that has been formed in advance at a temperature below the transformation temperature of the alloy so as to have a predetermined dimension and shape (shown as 14' in FIG. 3) with a vertically elongated shape that closes the pores is cooled to a temperature below the transformation temperature of the alloy. It is obtained by deforming it into a flat plate shape with predetermined dimensions as shown as 14 in FIG. 3, and due to the shape memory effect, the size and shape shown as 14' in FIG. 3 are restored at high temperatures. .゛Figures 4 and 5 show longitudinal sectional views of main parts of other embodiments of the ignition plug of the present invention, with Figure 4 showing its state at low temperatures and Figure 5 showing its state at high temperatures. The same parts as in FIGS. 2 and 3 are indicated by the same reference numerals.

As shown in the figure, in the spark plug of this embodiment, the shape memory member 15 disposed between the rear end surface of the enlarged diameter portion of the core body 11'- of the center electrode 11' and the fixing member 13 is A wire rod with a square or circular cross-sectional shape (the figure shows a square wire rod) made of an alloy similar to that used in the examples was bent at a temperature higher than the transformation temperature to obtain a predetermined size as shown in Fig. 6. After forming it into an arc shape, it is cooled to below the transformation temperature and deformed into a straight shape with bent parts 15t at both ends as shown in the figure (-).
This shape memory alloy member 15 has a convex portion 15a formed in the center of its upper surface, and the convex portion 15a is connected to the fixing member 13.
It is fitted and fixed into the four parts 13a provided at the center of the front end face of the center electrode, and the bent parts 15b at both ends are connected to the core body 11'- of the center electrode, and the two recesses i1'-zb bored in the rear end face.
As shown in FIG. 4, when the temperature is low, the shape memory member 15 is linear, and the core body 11' of the center electrode 11' is pulled up to form the gaps G, , G2.
is formed, and at high temperatures, as shown in FIG. 5, the shape memory alloy member 15 restores its shape to an arcuate shape due to the shape memory effect and slides the core 11'z of the center electrode 11' toward the tip. This is to close the gap G□eJ, and the other structure is the same as that of the previous embodiment.

In addition, as shown in FIG. 7, the shape memory alloy member 15 is upside down compared to the embodiments shown in FIGS. '-, a structure in which the recess 11'-*c Vc provided on the rear end surface is fitted and fixed, and the bent portions 15k at both ends thereof are respectively fitted and fixed into the recesses 13b bored on both sides of the tip of the fixing member 13. In this case, since the shape memory alloy member 15 has a flat plate shape at low temperatures, a gap G15G* is formed by pulling up the core body 11'- of the center electrode 11'; Shape memory stand ° metal member 15
can function to close the gap G1°G by sliding the core body ii'- in an arcuate direction toward the distal end.

Figures 8 and 9 show longitudinal sectional views of main parts of still another embodiment of the ignition plug of the present invention, with Figure 8 showing the state at low temperatures and Figure 8 showing the state at high temperatures, respectively. This is what is shown. Note that the same parts as in FIGS. 4 and 5 are indicated by the same reference numerals.

As shown in the figure, in this embodiment, the center electrode 11
As the shape memory member 16 disposed between the rear end surface of the enlarged diameter part of the core body 11'-* and the fixing member 13, a strip or wire made of an alloy similar to that in the previous embodiment is used. , the alloy is formed into a straight line of predetermined dimensions as shown in FIG. 10 (A) (the figure shows the one using a strip material) above the transformation temperature of the alloy, and then cooled below the transformation temperature to form the shape shown in FIG. (C
As shown in IK, the length in the axial direction at the central portion, leaving both ends 16a and 16t), is the gap G□ in FIG. 8 at a low temperature.

This shape memory member 16 is formed by bending it into a waveform so as to have dimensions that form G2. The lower end portion 161) is fitted and fixed into the recess 11''-2b bored in the center of the rear end surface of the core 11''-8 of the center electrode 11''. As shown in FIG. 8, the core body 11''-2 of the center electrode 11'' is pulled up by the shape memory member 16, which is bent into a waveform and has a shortened axial length, to form a gap G1eJ. In this case, the shape memory alloy member 16 restores its shape to a straight line as shown in FIG. Move the gap G1. G
, which functions to close the .

Note that the fixing member 13 in the spark plug of the present invention is not limited to the fixing method using a glass seal as described above, but may also be a terminal that is screwed into a screw portion threaded in the rear end of the shaft hole of the insulator 10. A structure may be adopted in which the shaft is fixed using an adhesive and the tip of the terminal shaft is pressed so as to come into contact with the rear end surface of the fixing member 13.

The spark plugs shown in each of the above embodiments have the structure of the center electrode as described above, so that when the engine is running at low speed and the temperature is low, the center electrode is A shape memory alloy member is disposed between the rear end surface of the core body and the fixing member in the inner cavity of the rear end of the mantle, and a part or both ends thereof are fixed to the fixing member and a part of the rear end surface of the core body. The insulator is shortened in length with respect to the direction and the center electrode is pulled up, a gap G is formed at the tip of the lumen of the mantle, and a gap G is formed in the lumen of the enlarged diameter part on the rear end side. The heat transfer from the legs to the center electrode is reduced and the temperature is increased to burn off carbon, oil, etc. adhering to the leg surface, improving stain resistance. The shape of the memory member is restored to a slightly elongated or arcuate shape due to its shape memory effect, and is pressed and slid toward the core tip side of the center electrode to close the gaps G, , G, thereby forming the insulator legs. By lowering the temperature (with good heat conduction from the fuel to the center electrode) and keeping the legs at an appropriate temperature, premature ignition is suppressed and a drop in output can be prevented.

As can be understood from the above description, the spark plug of the present invention has excellent thermal characteristics that can be used under operating conditions ranging from low speeds to high speeds, solves the problems with conventional spark plugs of this type, and can be used over a wide range of temperatures. It can be provided as a spark plug with a range.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view of the main parts of a conventional example of a spark plug.
Figures 2 and 6 are longitudinal cross-sections of main parts of the embodiment of the spark plug of the present invention.
The figures show the states at high temperatures, and Figures 4, 5, and 7, as well as Figures 8 and 9, are longitudinal sections of main parts of other embodiments of the spark plug of the present invention. In the figure, the fourth
Figure 8, the 8th factor is the state at low temperature, Figure 5, 7
9 and 9 respectively show the state at high temperatures, FIG. 6 is an explanatory diagram of the shape of the shape memory alloy member in FIGS. 4 and 5, and FIG. 10 is the shape of the shape memory alloy member in FIGS. 8 and 9. It is a shape explanatory view of a shape memory alloy member. 1, ii, 1i', 11": center electrode, la, 1i-,
. 11'-,, 11"-4: cloak, 1 b, 11-t-1
1'-x. 11"-,: core body, 4,10 double insulation, 1l-ta two-stage crotch seat 1l-sa: flange w 1l-zb # 11'-x
b #11'-zc #11'-* b #13
b: recess, 12: gun sealing material, 13: fixing member, 1
4, 15, 16: Shape memory alloy member, 1'4a, 15a
: Convex part, 15b: Fll1 part, 16a: Upper end part s1
6b: Lower end, G, G, , G,: Gap agent Patent attorney Mamoru Takeuchi

Claims (1)

[Claims] The center electrode held in the shaft hole of the insulator is made of N1 or its alloy, has an enlarged diameter portion formed on the rear end side, and has a bottomed inner cavity, and a heat shield that is slidably inserted into the inner cavity. It is made of a core made of a highly conductive metal, and is connected between the bottom of the tip of the inner cavity of the mantle and the tip of the core, and between the crotch seat of the enlarged diameter section on the rear end side and the enlarged diameter flange of the core. A gap is provided between each of them, and a fixing member is disposed at the rear end of the enlarged diameter portion of the mantle and is in contact with the end surface and sealed in the inner cavity of the insulator. A shape memory alloy member is disposed between the rear end surface of the core body and the fixing member, and has a memory shape that presses against the tip side of the core body at high temperatures to close the gap. Alternatively, a spark plug characterized in that both ends of the spark plug are fixed to a fixing member and a part of a rear end surface of a core.