JP2003308945A - Ignition plug - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to realize a larger cooling passageway, outlet passageway, and inlet passageway compared with a conventional technology in a cylinder head especially in the region of cone closure seat by making a space required for an ignition plug smaller. <P>SOLUTION: In the ignition plug in which a screw-thread shaft 14 having a screw-thread 16 and a tool fitting part 13 is constituted in a case 12 to be built in the case to be assembled in an internal combustion engine, and which has the case 12 with a type that an assembly shaft 20 of the case 12 is extended between the screw-thread shaft 14 and the tool fitting part 13, the ratio of the sum of a screw-thread shaft nest length L1 of the screw-thread shaft 14 and an assembly shaft length L2 of the assembly shaft 20 to the sum of an assembly shaft diameter D1 of the assembly shaft 20 and a screw-thread diameter D2 of the screw-thread 16 is within the range of 0.95 to 1.55. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention, as specified in claims 1 and 6 of the appended claims as a superordinate concept of the invention, includes a screw thread and a tool mounting portion for incorporation into an internal combustion engine. A spark plug of the type in which the threaded shaft has a casing and the assembly shaft of the casing extends between the threaded shaft and the tool mount.

[0002]

2. Description of the Prior Art Spark plugs of the above type are already known and are designed for use in gasoline internal combustion engines (see, for example, US Pat.

Known spark plugs have a substantially tubular metal casing in which the threads for fixing in the cylinder head of an internal combustion engine and the means for mounting in the internal combustion engine. A hexagonal wrench fitting part is formed. The casing has a through-hole in which a substantially rotationally symmetrical electrical insulator is arranged, which electrical insulator is formed in the end section of the casing close to the combustion chamber. A so-called central electrode cooperating with the ground electrode is fixed.

In the installed position, the end section of the casing or spark plug near the combustion chamber has penetrated into the combustion chamber.

In practice, what is important is to design the internal combustion engine so that the combustion consumption rate and the toxic gas emission value of the internal combustion engine are low. In this connection, it is also essential to cool the internal combustion engine sufficiently to obtain high thermal efficiency, which is done via the cooling passages. In order to be able to design the cooling passages to be sufficiently large, it is necessary for the spark plug incorporated in the cylinder head of an internal combustion engine to require only a limited installation space.

[0006] However, if this is attempted to be achieved by using a conventional spark plug, in return, it is unavoidable that the mechanical and electrical characteristics of the spark plug are unduly changed.

[0007]

[Patent Document 1] European Patent No. 0 101 547

[0008]

The object of the present invention is to reduce the space required for the spark plug and to provide a larger cooling passage in the cylinder head, especially in the region of the sealing seat, in comparison with the prior art. It is to be able to realize an outlet passage and an inlet passage.

[0009]

According to a first aspect of the present invention, there is provided a constitution means for solving the above-mentioned problems, wherein a sum of a thread shaft incorporating length of a thread shaft and an assembling shaft length of an assembling shaft, and assembling. The ratio of the sum of the assembled shaft diameter of the shaft and the thread diameter of the thread lies in the order range 0.95 to 1.55, and according to claim 6, the thread of the thread shaft. The ratio of the sum of the shaft built-in length and the assembled shaft length of the assembled shaft to the sum of the assembled shaft diameter of the assembled shaft and the thread diameter of the thread is 1.
It is at a point greater than 38 or equal to 1.38.

By virtue of the construction means of the present invention, the cooling passage of the cylinder head and the outlet valve and the inlet valve can be made relatively large, so that a high output of the internal combustion engine can be obtained at the same time as thermodynamically preferable combustion. It will be possible.

In order to reduce the working temperature and the natural vibration of the ground electrode, a spark plug having a length / diameter ratio of the present invention has a significantly longer thread or thread shaft than conventional spark plugs. It has a kind of thread additional extension as a component. The thread is generally a component of a plug casing that houses a so-called plug stopper.

The size of the spark plug according to the invention is such that all the requirements that the spark plug imposes on modern spark plugs in spite of the reduction in construction space obtained compared to spark plugs according to the prior art ( For example, it is designed so as to satisfy sufficient dielectric strength and high torsional strength.

In the spark plug of the present invention, there is no risk of vibration damage to the ground electrode, or the temperature acting on the spark plug penetrates deeply into the combustion chamber of the internal combustion engine without exceeding the allowable value of the material used. Sufficient spark position is realized. Therefore, the spark plug of the present invention is particularly suitable for use in a direct fuel injection system.

The spark plug according to the present invention has a thread diameter of 12 mm and a thread shaft mounting length of the thread shaft of 19 mm to 22 mm, in particular, a spark shaft mounting length of the thread shaft. The ratio of the sum of the assembly shaft length of the assembly shaft and the sum of the assembly shaft diameter of the assembly shaft and the thread diameter of the screw thread is 1.08 to
The value is 1.20, or the ratio is 1.20 to 1.50 when the thread shaft mounting length of the thread shaft is 25 mm to 29 mm, or the thread shaft of the thread shaft. Built-in length is 17.5mm-22
When it is mm, it can be designed so that the ratio takes a value of 0.94 to 1.05.

In order to be able to accurately position the ground electrode in the combustion chamber of the internal combustion engine, the spark plug according to the invention is advantageously designed with a conical sealing seat. Advantageously, the conical seat is located in the transition zone between the threaded shaft and the assembly shaft.

An assembly shaft that is optimal in terms of construction space has, for example, a ratio of assembly shaft diameter to assembly shaft length of 1.3.
Advantageously, it is less than 0 or greater than 1.70, ie 1.26 or 1.72, for example.

The spark plug according to the invention has indexing means in order to allow the grounding electrode to be accurately oriented in a combustion chamber having a small tolerance. This indexing means is, for example, a mark attached to the assembly means consisting of double hexagonal parts. This mark may consist of markings, such as holes, notches or color dots, which are displayed on the connecting nut or connecting bolt. It is also possible to provide colored markings on the electrical insulator.

In order to optimize tightening of the plug stopper of the spark plug in the casing of the spark plug,
Advantageously, the compacted powder package is arranged in the ring gap between the plug stopper and the plug casing. In order to produce a powder package, for example of talc, the powder is loaded and compacted in the gap between the plug stopper and the plug casing during assembly of the spark plug. During final assembly of the spark plug, the edges of the plug casing are deformed radially in the direction of the plug stopper. The edge of the casing compacts the powder package during its radial deformation, whereby the plug stopper is clamped into the plug casing.

In order to optimize the compaction of the powder package, the powder package can be restricted by a press ring on at least one side in the axial direction of the plug stopper. In this case, during final assembly of the spark plug, the casing edge also deforms radially in the direction of the plug stopper, so that the casing edge cooperates with the press ring to compact the powder package. Due to the compaction of the powder package, the plug stopper is clamped in the plug casing, so that a high heat-sealing property is guaranteed.

If the powder package is restricted on both sides by one pressing ring, respectively, a particularly good compaction of the powder package and thus also a good heat-sealing property of the ignition plug are obtained.

Further advantages and advantageous embodiments of the spark plug according to the invention can be easily conceived on the basis of the detailed description of the drawings and the dependent claims.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings.

The spark plug 10 shown in FIG. 1 is designed for installation in an internal combustion engine equipped with a direct fuel injection device, which is not shown in detail. The spark plug 10 comprises a substantially tubular metal casing 12, which comprises a tool fitting in the form of a double hexagon 13 as well as a threaded shaft 14 for mounting in the cylinder head of an internal combustion engine. have. The thread shaft 14 includes a thread 16 (configured as a metric ISO thread in the present example) as schematically shown in the drawing, as well as a thread addition for connecting to the thread 16 in the axial combustion chamber direction. Have eighteen.

Thread shaft 14 and double hexagonal portion 13
Between the housing 12 and the housing 12 is constructed as a substantially cylindrical assembly shaft 20, which has a contraction area 22 in the transition area to the double hexagonal section 13 and is assembled. In position, it is substantially submerged in the cylinder head.

In the transition region between the screw shaft 14 and the assembly shaft 20, a conical sealing seat 24 is formed on the outer surface side of the casing 12, which in this example is a cone of about 63 °. It has an angle α and guarantees in this region the sealing of the combustion chamber against the surrounding atmosphere.

A so-called ground electrode 26 is arranged in the metallic casing 12 at the end near the combustion chamber, which is formed in a conventional manner and, as is customary, a so-called central electrode 28. Collaborate with. The central electrode is
The plug stopper, which is fixed to the electric insulator 30 of the plug stopper 31 and is made of substantially aluminum oxide in this example, penetrates the casing 12 in the axial direction and is separated from the central electrode 28. It is connected to the contact terminal 32 at the end.

In the illustrated embodiment, the structural total length G of the spark plug 10 extending from the end face of the casing 12 near the combustion chamber to the end face of the contact terminal 32 on the connection side is 84.9 mm.
The assembled shaft 20 in this case has a diameter D1 of 14.5 mm
And the thread 16 has a nominal diameter or thread shaft diameter D2 of 12 mm. Furthermore, the spark plug 10 is 12.8 mm in the area of the conical sealing seat 24.
Has a test diameter DP of

The thread shaft 14 in this example has a built-in length L1 of 29 mm from the end face of the thread addition 18 to the position of the test diameter DP of the conical sealing seat 24. Experimental results show that for spark plugs with comparable dimensions, 25 to obtain the desired length / diameter ratio.
A thread shaft length greater than mm has been found to be advantageous. In this example, the thread length LG of the thread 16 reaches 24.3 mm as measured from the test diameter DP at the conical sealing seat 24.

The assembly shaft 20 has an assembly shaft length L2 of 11.4 mm from the position of the test diameter DP at the conical sealing seat 24 to the double hexagonal portion 13.

The ratio of the sum of the thread shaft installation length L1 and the assembly shaft length L2 to the sum of the assembly shaft diameter D1 and the thread shaft diameter D2 is 1.53 in this embodiment, which is essentially detected. The critical value is greater than 1.38.

Based on the displayed dimension value, the spark plug 10 realizes the optimum screw thread length for optimizing the spark position and reducing the required space.

FIG. 2 shows a spark plug 40 according to a second embodiment of the present invention. The spark plug 40 differs from the spark plug 10 of FIG. 1 in that the threaded shaft 14 has a built-in length L1 of 20 mm. The assembled shaft 20 is 11.4 m in this embodiment as well.
It has an assembly shaft length L2 of m and an assembly shaft diameter D1 of 14.5 mm. The threads 16 of the thread shaft 14 also have a nominal diameter D2 of 12 mm.

The ratio of the sum of the thread shaft mounting length L1 and the assembly shaft length L2 to the sum of the assembly shaft diameter D1 and the thread shaft diameter D2 is 1.18 in this embodiment.

Further, the spark plug 40 and the spark plug 1 of FIG.
The difference from 0 is that a compacted powder package 41 made of talc is arranged in a ring gap 44 arranged between the plug casing 12 and the plug stopper 31, and the powder package is formed by the plug stopper 31. The first press ring 42 on one side and the second side on the other side in the axial direction of
It is limited by the press ring 43. The first press ring 42 borders the ring collar 46 of the plug stopper 31. The second press ring 43 is in contact with the edge 45 of the casing 12, which is deformed in the radial direction when viewed in the direction of the plug stopper 31.

FIG. 3 shows a spark plug 50 according to a third embodiment of the present invention. The spark plug 50 is
The difference from the spark plug 40 of FIG. 2 is that the threaded shaft 14 has a built-in length L1 of 25 mm. The assembly shaft 20 has an assembly shaft length L of 8.6 mm.
It has an assembled shaft diameter D1 of 2 and 15.54 mm. The thread 16 of the thread shaft 14 is also 12 m
It has a nominal diameter D2 of m.

In short, the ratio of the sum of the thread shaft installation length L1 and the assembly shaft length L2 to the sum of the assembly shaft diameter D1 and the thread shaft diameter D2 is 1.22 in this embodiment.

[Brief description of drawings]

FIG. 1 is a schematic partial vertical sectional view of a spark plug according to a first embodiment.

FIG. 2 is a schematic partial vertical cross-sectional view of a spark plug according to an alternative second embodiment.

FIG. 3 is a schematic partial vertical sectional view of a spark plug according to a third embodiment.

[Explanation of Codes] 10 Spark Plug, 12 Casing, 13 Double Hexagonal Part as Tool Fitting Part, 14 Thread Shaft, 16 Thread, 18 Thread Addition Part, 20 Assembly Shaft, 22 Shrink Area, 24 Conical Seal Stop,
26 ground electrode, 28 center electrode, 30 electric insulator, 31 plug stopper, 32 contact terminal, 40
Spark plug, 41 powder package, 42 1st
Press ring, 43 second press ring, 44 ring gap, 45 edge, 46 ring collar,
50 Spark plug, α cone angle, G Overall length of spark plug, D1 Assembly shaft diameter, D2 Thread nominal diameter or thread shaft diameter, DP test diameter, L1 thread shaft built-in length, L2 assembly shaft length, LG screw Mountain chief

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hans-Jörg Lip             United States Michigan Farmint             Hills Hills Tech Drive             38000 (72) Inventor Gimon Schmittinger             Federal Republic of Germany Renningen Wilge             Rumstrasse 13 F term (reference) 5G059 AA08 CC02 GG03 GG05 JJ10

Claims (12)

[Claims] 1. Threads for mounting in an internal combustion engine (1
6) and a threaded shaft (14) having a tool fitting part (13) are formed in the casing (12), and between the threaded shaft (14) and the tool fitting part (13). In a spark plug having a casing (12) of the type in which the assembly shaft (20) of the casing (12) extends, a thread shaft incorporating length (L1) of the thread shaft (14) and the assembly shaft (20). The assembly shaft length (L2) of the assembly shaft diameter (D1) and the thread diameter (D) of the assembly thread (16) (D1)
A spark plug with a casing, characterized in that the spark plug (40) is dimensioned such that the ratio of the sum with 2) is in the order range 0.95 to 1.55. 2. The ratio when the thread diameter (D2) of the thread (16) is 12 mm and the thread shaft mounting length (L1) of the thread shaft (14) is 19 mm to 22 mm. The spark plug according to claim 1, which has a value of ˜1.20. 3. The said ratio when the thread diameter (D2) of the thread (16) is 12 mm and the thread shaft mounting length (L1) of the thread shaft (14) is 25 mm to 29 mm. The spark plug according to claim 1, having a value of ˜1.50. 4. The ratio is 0 when the thread diameter (D2) of the thread (16) is 12 mm and the thread shaft built-in length (L1) of the thread shaft (14) is 17.5 mm to 22 mm. A value of 0.95 to 1.05 is set.
The described spark plug. 5. The spark plug according to claim 3, wherein the diameter (D1) of the assembly shaft (20) is 15.54 mm. 6. Threads for mounting in an internal combustion engine (1)
6) and a thread mounting shaft (14) having a tool mounting portion (13) are formed in the casing (12), and the screw shaft (14) and the tool mounting portion (13) are provided between the screw thread shaft (14) and the tool mounting portion (13). In a spark plug having a casing (12) of the type in which the assembly shaft (20) of the casing (12) extends, the assembly of the thread shaft built-in length (L1) of the thread shaft (14) and the assembly shaft (20). The ratio of the sum of the shaft length (L2) and the sum of the assembled shaft diameter (D1) of the assembled shaft (20) and the thread diameter (D2) of the thread (16) is greater than 1.38. A spark plug with a casing, characterized in that the spark plug (10) is dimensioned to be equal to or equal to 1.38. 7. The spark plug according to claim 6, wherein the thread shaft (14) has a thread shaft built-in length (L1) of 25 mm or more. 8. The thread shaft assembly length (L1) of the thread shaft (14) is 29 mm, the assembly shaft length (L2) of the assembly shaft (20) is 11.5 mm, and the assembly shaft length (20). Assembly shaft diameter of (D
Spark plug according to claim 6 or 7, wherein 1) is 14.5 mm and the nominal diameter (D2) of the threads (16) is 12 mm. 9. The casing (12) has a conical sealing seat (2).
The spark plug according to any one of claims 1 to 8, which is configured to have 4). 10. The spark plug according to claim 1, further comprising indexing means for positioning the ground electrode (26). 11. Between the casing (12) and a plug stopper (31) penetrating the casing (12),
A compacted powder package (41) is arranged by means of which the plug stopper (3
Spark plug according to any one of claims 1 to 10, wherein 1) is clamped in the casing (12). 12. The powder package (41) is bounded on at least one side in the axial direction of the plug stopper (31) by a press ring (42, 43).
The described spark plug.