JPS5840789A - High voltage 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 PRIOR ART The present invention comprises a metallic, substantially tubular casing having means on its exterior for mounting within an internal combustion engine and having a substantially tubular casing in its throughbore. A rotationally symmetrical insulator is provided in a hermetically sealed manner, and has a ground electrode at its end on the combustion chamber side, which faces the center electrode at a distance (spark gap). The center electrode is sealed and fixed in the elongated hole of the insulator without any gaps on the combustion chamber side, and is conductively connected to the connecting terminal delt protruding from the connecting terminal side end of the insulator, and This relates to a high-voltage spark plug that protrudes up to 1 meter from the front. Such a spark plug, already known from US Pat. No. 2,265,352, has a tendency to cause undesirable sliding spark discharges and thereby ignition interruptions. This is because the spherical shape causes combustion particles to deposit in the center electrode region and insulator region on the side of the combustion chamber: this type of spark plug therefore has unsatisfactory ignition characteristics, requires a relatively high ignition voltage, and has a relatively high ignition voltage, and the center electrode region The multi-layer structure in the material and cost is expensive.

Furthermore, a known spark plug (U.S. Pat. No. 2,251,171) uses a center electrode that covers the combustion chamber side end face of the insulator with a flat head. Although this type of spark plug has a small tendency to cause slipping spark discharge, the ignition characteristics are also not satisfactory with this spark plug; the unsatisfactory ignition characteristics are probably due to the configuration of the combustion chamber side of the spark plug, e.g. This is due to the bulky structure of the insulation, which reaches the free-burning temperature relatively slowly when starting at low temperatures, and possibly due to the unfavorable introduction of fuel/air/air mixture in the area of the spark gap.

Effects of the Invention The high-voltage spark plug according to the invention having the features set out in claim 1 has the following advantages over it:
It exhibits advantageous ignition characteristics in all operating conditions of internal combustion engines based on the configuration of the center electrode, insulation, body, ground electrode), requires normal ignition voltage, does not cause slipping spark discharge and ignition interruption, and is suitable for industrial The spark plug is superior in terms of production technology and cost due to its standard production: in addition, the spark plug has a characteristically high durability and is very low in terms of free combustion temperature during cold starting and engine braking in internal combustion engines. No problems and does not cause scorching ignition under load in internal combustion engines.

An advantageous embodiment of the spark plug according to claim 1 is possible with the features shown in the exemplary embodiment section. Particularly advantageous is the use of precious metals in the center electrode of the spark plug according to the invention: if thin nails of precious metals, ceramics mixed with precious metals or conductors containing precious metals are used as center electrodes, expensive precious metals are required. quantity becomes very small.

Embodiments of the present invention will be described in detail below using the drawings.

DESCRIPTION OF THE EMBODIMENTS Spark plug 1 according to the invention shown in FIGS. 1 and 2
The combustion chamber side part of 0 has a metal casing 11, and this metal casing j has a screw thread 12 on the outside thereof and a first screw thread 12 for mounting a large dot plastic / 10 in the cylinder head of the engine (not shown). A metal seal ring 13 is provided at the connecting end of the thread 12 in order to attach the spark plug 10 to the cylinder head with a flat seal seat. It is being The metal casing 11 surrounds a rotationally symmetrical insulator 15 in a known manner with a perforation 14 and carries a linear earth electrode 16 at the end of the casing facing the combustion chamber. The insulator 15 is made of aluminum oxide, for example, and is hermetically fixed in the casing through-bore 14 by flanging and shrink-fitting (with the interposition of a sealing ring 17 if necessary) in a known manner, the hole diameter being graduated. have different long holes 18: insulator 1
5 can, however, also be fixed hermetically within the metal casing 11 by cementing or similar methods. The elongated hole 18 in the connection terminal side area of the insulator has a larger diameter than the area connected to the combustion chamber side, houses the combustion chamber side part of the metal connection terminal tilt 19, and is expressed as 1δ/1. ing. As is known, conductive molten glass 20 is sealed in the range of the insulator-elongated hole 1δ that is connected to the combustion chamber side (it may additionally contain a resistive member). This part is indicated by &18/2. The area on the side of the combustion chamber has the smallest diameter of the insulator slot 18 and is used to accommodate the center electrode 21, and is designated by 1δ/3. In the connection terminal side range 1δ/1 of the insulator long hole,
Projecting into it is a knurled or threaded connection terminal bolt 19 made of non-alloyed steel, the slot area of which has a diameter of approximately 4 mm. The elongated hole range 18/2 that connects to the combustion chamber side has a diameter of 2 mtx, and decreases by about 0.5 mtx toward the combustion chamber side, and passes through the waste-like stepped portion 22 to the combustion chamber side range 18/2 of the insulator elongated hole 1δ. reaches 3; insulator long hole 1
The combustion chamber side region 1δ/3 of 8 has a diameter of approximately 0.3 mm. The central electrode 21 (FIG. 3) made of a noble metal (preferably platinum metal) is composed of a shaft 23 and a flat spatula P24, and the end of the connection terminal 19 on the combustion chamber side projects into the conductive molten glass 20. The free end portion of the shaft 23 as the central electrode 21 protrudes as shown in FIG. The shaft 23 of the central electrode 21 has a diameter of 0.3 mm and is preferably tapered at its free end;
The center electrode 21 extends through the combustion chamber side elongated hole range 18/3 having a length of about 111 m without a gap, and its spatula P24 is in contact with the combustion chamber side end surface 25 of the insulator 15. The center electrode - spatula P24 has a diameter of 0.5 mm and a height of only about 0.1 mm.
It is mm.

The insulator end face 25 is substantially flat and has a diameter of 2 IIm; depending on the intended use, the center electrode 24 can also be made larger. The diameter of the insulator end face 25 is usually 1.5 to 3
III! So, 2 to 2.5 fins are advantageous. Insulator 1
The combustion chamber side end face 25 of No. 5 moves to a corner gouge cut part 26 as a part where the circumferential shaft with a gentle slope is removed, which is provided on the end face 25, and this corner gouge cut part is the combustion chamber side end part of the insulator 15. transition edges 27 and 28 are formed. The height from the insulator end face 25 to the transition edge 28, measured in the longitudinal direction of the spark plug 1o, is 1.5 mm, but may be between 0.8 and 3.0 Im; the transition edge The maximum depth of the corner gouge cut 26, measured by the imaginary line between 27 and 28, is 0.8 mtx, advantageously in the range of 0.4 mtx. The diameter of the insulator 15 in the area of the transition edge 28 depends on the application of the spark plug 10 and is 4.5 III in this embodiment. Insulator 1
The diameter in this range of 5 may be between 3.0 and 7.0 mm. Corner gouge cut section 26 with gentle slope
Alternatively, in extreme cases a frusto-conical transition from edge 27 to edge 28 is also possible.

The center electrode 21 is fitted with its axis into the combustion chamber side range 18/3 of the insulator elongated hole 18 as follows, i.e., the center electrode 21 is fitted in the pre-sintered insulator 15 on the combustion chamber side. It is introduced into the elongated hole area 18/3 and is finished sintered together with the insulator. As can be seen from FIG. 4, inserting the center electrode 21 into the combustion chamber side range 1δ/3 of the insulator elongated hole 18 can be rationally performed in the following manner. An annular notch 30 is provided at the same distance using one step or a rolling step, which simultaneously forms the convergent part of the flange and the center electrode shaft 23, which is formed as the center electrode spatula P24; the conductor 29 After inserting the center electrode 21 in front of the combustion chamber side range 18/3 of the insulator elongated hole 18, the center electrode 21 connected to the spatula r24 of the center electrode 21 is broken or cut by other methods. It is separated from the central electrode 21 in the front. Shaping or enlarging the diameter of the center electrode spatula r24 by crushing the center electrode spatula r24 protruding through the combustion chamber end face 25 of the insulator 15; before crushing the preformed center electrode head 24; Warming is also possible, and if necessary the spatula is heated to a temperature in the range from softening to melting. The aforementioned work steps can be easily automated in factory production.

The combustion chamber side end surface 25 of the insulator 15 has a relatively large diameter (for example, 3.8 n+), and the spatula r24 of the center electrode 21
If the electrode has to cover a large part of the end face 25 for the corresponding purpose (e.g. because a large wear volume is required), the center electrode spatula F″24 can be combined with additional electrode material to cover a larger part of the end face 25. The additional electrode material can then be attached to the preformed center electrode spatula P24 in the following way, i.e. a metal plate piece (not shown) consisting of the electrode material can be attached to the center. The noble metal is attached by welding to the electrode head 24 or on the end face 25 using suspension or electrolytic deposition (molten salt electrolysis, aqueous electrolysis). O, lyxm (depending on the purpose of use) approximately 1 ra
Thicknesses up to m are possible.

The center electrode- spatula R24 has a spark gap 31 of 0.8-
The ends of the ground electrodes 16 face each other at a distance of , and these ends are wider than the diameter of the combustion chamber side 25 of the insulator 15. In this embodiment, the earth electrode 16 is 2.5 ii+
It has a width of The width of the ground electrode 16 should be matched to the intended use of the spark plug 10. The earth electrode 16 is made of a corrosion-resistant metal in a known manner and is fixed to the spark plug housing 11, usually by welding.

Other advantageous embodiments for the construction and mounting of the central electrode 21 are shown below.

Hollow shaft 2 instead of solid center electrode 21 made of platinum
A center electrode 21 with 3 can be used.

The shaft 23 is then closed at its free end and the spatula P24
It is open to the public. This kind of center electrode 21'
can likewise be inserted into the insulator 15 with industrial success. In the embodiment according to FIGS. 1 to 4, when installing the spark plug 10, the center electrode 21 is inserted into the presintered insulator 15, but the center electrode 21 or 21 is inserted into the unsintered insulator 15. It is also possible to already push it into the .

It is also already known to use only a section of a noble metal wire instead of the nail-shaped central electrode 21 or 21; such a wire is advantageously already applied in its combustion chamber side region during the pressing of the insulator 15. Pushed in.

Other embodiments for the manufacture of suitable center electrodes (not shown)
In this case, a non-conductive rod-shaped member is coated with a conductive surface film (for example, platinum), and this type of center electrode is housed in the insulator 15 instead of the metallic center electrode 21. (See Federal Republic of Patent Publication No. 3038720). A conductive ceramic material can likewise be used as the center electrode 21 (see Patent No. 40534 of the Federal Republic of Italy).
2, for example a mixture of 75% Al2O3, 20% 0u20 and 5% 0r203) or a mixture of 60% Al2O3 and 40%
A central electrode 21 is used, consisting of platinum (composed of platinum of
(see Federal Republic of Italy Publication No. 2729099).

The ceramic-containing center electrode 21 described above has the following advantages: such a center electrode is better matched to the ceramic of the insulator 15 than the metallic center electrode 21 with respect to its coefficient of thermal expansion. The center electrode 2b described so far is sintered into the insulator 15.15 without any gaps, and is also fixed without any gaps into the completed sintered insulator 15.15 using a glass or cement adhesive using a known method. can.

In FIG. 6 a further variant for mounting the center electrode 21 in the insulator 15 is shown: this center electrode 21
is produced as follows: a noble metal suspension (preferably a platinum suspension) is introduced into the combustion chamber side region 18/3 of the insulator elongated hole 18 and sintered; When the insulator 15' is dropped into the insulator 15' which has not yet been completely sintered, the complete sintering is carried out together with the complete sintering of the insulator 15. However, the noble metal suspension can also be introduced into the combustion chamber side region 1δ/31' of the insulator slot 18 by any known method only after the insulator 15 has already been fully sintered; In this case, the center electrode 21 requires an additional sintering step for finishing.

This last-mentioned method is suitable for producing a spark plug 10 of this type, especially if the center electrode 21 is provided with a spatula l'24' of relatively large surface area. This is because, using the same noble metal suspension, such a spatula P24 can be installed in the same working process.

Additionally, an extension of the center electrode spatula P can be similarly made using such a noble metal suspension on the aforementioned center electrode which is not formed from a solid metal, or an extension of the center electrode spatula P can be made using such a noble metal suspension. Enlargement of r can be achieved by using conductive layers using molten salt electrolysis or aqueous electrolysis or (when using cermets) by welding noble metal plates. The center electrode 21, which has a relatively large diameter and, in some cases, a thickness of 1 mm, has the additional advantage of being durable.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view of the ignition part of the spark plug shown in an enlarged manner, Fig. 2 is a partial cross-sectional view of the spark plug taken along line A/B in Fig. 1, and Fig. 3 is a partial cross-sectional view of the ignition part of the spark plug. An enlarged cross-sectional view of the combustion chamber side end of the spark plug insulator and center electrode according to Figures 1 and 2, and Figure 4 shows the installation process of the nail-shaped noble metal electrode to the spark plug-insulator. 5 is an enlarged sectional view of another embodiment of the spark plug section shown in FIG. 3; FIG. 6 shows a spark plug-insulator combustion chamber with center electrode, side end portion FIG. 6 shows an enlarged cross-sectional view of another embodiment.

Claims (1)

[Scope of Claims] 1. A substantially tubular casing made of metal, which casing has means for mounting in an internal combustion engine on the outside thereof, and has a substantially rotationally symmetrical casing in its through-bore. An insulator is provided in a sealed manner, and has a ground electrode at its end on the combustion chamber side, and the ground electrode faces the center electrode at a distance (spark interval II). is sealed and fixed in the elongated hole of the insulator without any gaps on the combustion chamber side, and is electrically connected to the connection terminal quilt protruding from the connection terminal side end of the insulator, and from the combustion chamber side end face of the insulator. A high voltage ignition plug characterized in that in a high voltage ignition plug 2 that protrudes by a maximum of 1*m, a combustion chamber side portion of the insulator has a coaxial scraped portion. 2. The end surface (25) of the insulator (15, 15) is 1.5 to 3
11I+ diameter, the maximum depth of the scraped part is 0.8
2. The spark plug of claim 1, wherein the height of the scraped portion, measured in one shoulder and in the longitudinal direction of the center electrode (21, 21), is between 1 and 2.5 inches. 3. Insulator - Center electrode (21, 2 in the long hole (18)
2. The spark plug according to claim 1, wherein the portion 1, 21') is made of metal, conductive ceramic, or cermet, or is a conductor. Tip The center electrode (21, 21, 21) is flat I
〃 Spatula)' (24, 24, 24), the head is provided on one end surface (25) of the insulator on the combustion chamber side, and does not protrude beyond the end surface (25). Large dot plug as described in item 1. 5. The center electrode (21, 21) is a metal nail with a hollow shaft (23'), the hollow shaft being open to the spatula r (24') and closed to the free end; In particular, the first claim tapers towards the free end.
Spark plugs listed in section. 6. Spark plug according to claim 1, wherein the central electrode (21, 21) has a shaft (23, 23) with a diameter of at most 0.5 n+ and is made of a noble metal, for example platinum.