WO2012163578A1 - Spark plug having reduced installation dimensions - Google Patents

Abstract

The invention relates to an insulator (7) and a seat support (4) arranged at a sub-region of the insulator (7) and encircling the insulator (7) in a circumferential direction, wherein the seat support (4) is arranged closer to an end at the combustion chamber side than to an end on the connection side of the spark plug. The insulator (7) is provided with a first circumferential shoulder (10) having a first diameter (D1), wherein on the combustion chamber side of the shoulder (10), a combustion chamber side base area (11) having a second diameter (D2) is provided. The seat support (4) has a maximal seat support diameter (S1), wherein the diameter (D2) of the base area (11) at the combustion chamber side and the maximal outer diameter (S1) of the seat support (4) equal D2 = t * S1, with 0.8 ≥ t ≥ 0.5.

Description

 description

title

 Spark plug with reduced mounting dimensions prior art

The present invention relates to a spark plug for an internal combustion engine with reduced installation dimensions. Spark plugs are different from the prior art

 Embodiments known. So far, spark plugs are screwed by means of a provided on a housing thread in a cylinder head. However, the modern multi-valve technology with enlarged inlet and outlet ports as well as the close installation position at the injection valve required for direct injection require a constant reduction of the installation space of the spark plugs. This refers in particular to reduced diameter of the spark plug. The insulation of the high voltage in the spark plug, however, requires minimum wall thicknesses, which preclude a reduction in diameter of the spark plug. Disclosure of the invention

The spark plug according to the invention with the features of claim 1 has the advantage that a reduced diameter at the spark plug is possible. As a result, a space for the spark plug can be reduced. Nevertheless, the spark plug according to the invention has no disadvantages with regard to the sealing function between the combustion chamber and the outside of the internal combustion engine. This is inventively achieved in that the spark plug comprises an insulator for insulating a center electrode and a seat support, which is arranged on a portion of the insulator. The seat support has a tubular basic shape and surrounds the insulator completely in the circumferential direction at a portion of the insulator, which is arranged closer to a combustion-chamber-side end of the spark plug than at a connection-side end of the spark plug. The insulator has a first circumferential annular shoulder with a first diameter D1. On the combustion chamber side of the shoulder, a foot region with a second diameter D2 is provided. The seat support has a maximum outer seat support diameter S1, wherein the second

Diameter D2 and the maximum outer seat support diameter S1 satisfy the following equation:

D2 = t * S1, where 0.8> t> 0.5.

By adhering to this equation, a wall thickness of the insulator can be optimized and a total diameter of the spark plug, which at the combustion chamber end of the spark plug by the maximum outer

Seat carrier diameter is determined to be minimized.

The dependent claims show preferred developments of the invention.

The seat body is preferably arranged on the combustion chamber end of the spark plug. An axial length of the seat body is 1/4 or less of an axial total length of the spark plug.

More preferably, the constant t is in a range of 0.6> t> 0.55, and more preferably 0.56.

More preferably, the insulator has at a connection-side end of the shoulder an annular recess with a minimum third diameter D3, wherein the third diameter D3 is greater than the second diameter D2 at the combustion chamber end of the shoulder.

Particularly preferably, the third diameter D3 and the first meet

Diameter D1 the following equation 2:

D3 = k * D1, where 0.9>k> 0.8, in particular 0.83>k> 0.81 and k is particularly preferably equal to 0.82. Particularly preferably, the spark plug according to the invention is thread-free, ie, no thread is provided on the spark plug. This leads to a further space reduction of the spark plug. Fixation of the spark plug in

Spark plug shaft is then done for example by bracing.

Preferably, the spark plug further comprises a separate lock nut or a separate bayonet element to fix the spark plug in the spark plug well. Alternatively, the spark plug preferably has a clamping claw, which the

Clamp the spark plug in the spark plug shaft. The clamping claw is supported on a shoulder of the spark plug and is fixed by means of screws in the cylinder head. As a result, the screw force on the clamping claw on the

Transfer candle shoulder. The clamping claw preferably comprises at least two arms, which face each other by 180 °. Alternatively, the clamping claw may also have three or four arms or be formed annular.

Particularly preferably, the insulator further comprises a flattening which is arranged to come into contact with a corresponding flattening provided on the spark plug shaft in order to provide an anti-twist device for the spark plug.

Preferably, the clamping claw thereby braces several spark plugs

simultaneously.

More preferably, the seat body is secured by means of a crimping collar in the provided at the connection end of the shoulder annular recess.

drawing

Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In the drawing is: 1 shows a schematic, partially sectioned spark plug according to a first embodiment of the invention,

Figure 2 is an enlarged fragmentary sectional view of Figure 1, and

Figure 3 is a schematic, partially cut-away spark plug according to a second embodiment of the invention.

Preferred embodiments of the invention

Hereinafter, with reference to Figures 1 and 2 a

Space-optimized spark plug 1 with a partially arranged in a combustion chamber 60 combustion chamber end according to a first

Embodiment of the invention described in detail.

The spark plug 1 includes a center electrode 5, a ground electrode 6, and an insulator 7. The reference numeral 8 denotes a terminal nut.

Furthermore, the spark plug 1 comprises a seat support 4, which is arranged at a combustion chamber end of the spark plug 1. The seat support 4 is fixed by means of a bead 40 in an annular recess 12 on the insulator 7. As can be seen from FIG. 1, the seat support 4 has a length L1 in the axial direction X-X of the spark plug, which is approximately 1/4 of an overall length L of the spark plug. Further, a clamping nut 3 is provided, which the spark plug 1 at a

Cylinder head 2 mounted in a spark plug shaft 20.

The insulator 7 comprises an annular projecting, first shoulder 10, which is covered by the seat support 4 (see Figure 2). On a combustion chamber side of the shoulder 10, a combustion chamber-side foot region 1 1 is formed on the insulator 7.

At the connection side of the shoulder 10, the annular recess 12 is formed.

As can be seen in particular from FIG. 1, a second shoulder 21, on which the clamping nut 3 clamps the spark plug 1 on the cylinder head 2, is also formed on the insulator 7. The clamping nut 3 also has a crimp collar 22 on, with which the clamping nut is arranged on the second shoulder 21 like a sleeve. Between a nut head 25 of the clamping nut 3 and the crimp collar 22, a clearance 23 is formed, whereby the clamping nut in a certain range in the axial direction on the insulator 7 is displaceable. For mounting, the clamping nut 3 has an external thread 24, which can be brought with an internal thread 26 formed in the spark plug shaft 20.

As can be seen further from FIG. 2, the insulator 7 has a first one

Diameter D1 at the shoulder 10, wherein the shoulder 10 is formed cylindrically in this area. The combustion chamber-side foot region 1 1 has a second diameter D 2 on the insulator 7. The annular recess 12 is arc-shaped in section and has a minimum third diameter D3. The seat carrier 4 has a maximum first seat carrier diameter S1. S2 denotes a minimum inner second seat carrier diameter. On the seat support 4, an inner shoulder 41 is further provided, which is directed radially outward and an inner diameter of the seat support 4 from the second seat support diameter S2 increases to a third seat support diameter S3. Furthermore, with S4 an outer diameter of the seat support 4 in the region of the shoulder 10 is provided which is slightly smaller than the maximum first seat support diameter S1 of the seat support 4.

So that the spark plug 1 has the smallest possible maximum outer diameter, a ratio of the second diameter D2 at the combustion chamber side foot region 11 of the shoulder 10 to the maximum first seat carrier diameter S1 of the seat support 4 is defined as follows:

D2 = t * S1 (Equation 1), where 0.8> t> 0.5. In this embodiment, t = 0.56.

Further, a ratio of the third diameter D3 of the annular

Recess 12 to the first diameter D1 at the shoulder 10 of the insulator 7 as follows:

D3 = k * D1 (Equation 2), where k> 0.8 and in this embodiment k = 0.82.

Furthermore, the seat support 4 is constructed such that the second Sitzträger- diameter S2 on the seat support 4 is less than or equal to the third Sitzträger- diameter S3 at the breathing chamber 13 and the third diameter D3 smaller than the third seat support diameter S3 of the seat support 4 at the Building side side of the shoulder 10 of the insulator. 7

Thus, according to the invention, the maximum outer diameter of the spark plug near the combustion chamber while ensuring sufficient isolation of the electric potential between the center electrode 5 and the seat of the

 Seat support 4 can be ensured in the cylinder head 2. For sealing between the insulator 7 and the seat support 4, a sealing washer 9 is also provided.

As can be seen in particular from Figure 2, the sealing disc is in the axial direction between the combustion chamber side foot area 1 1 and the

Shoulder 10 in a tapered region 14 between the shoulder 10 and the combustion chamber side foot area 11th

Hereinafter, a spark plug 1 according to a second embodiment of the invention will be described in detail with reference to Figure 3, wherein like or functionally identical parts are designated by the same reference numerals as in the first embodiment.

In contrast to the first exemplary embodiment, the spark plug of the second exemplary embodiment has a clamping claw 50 instead of the clamping nut. The

Clamp 50 has a first and a second in the axial direction X-X projecting arm 51 and 52, which are opposite to each other along the circumference of the spark plug 1 by 180 °. The arms 51, 52 are supported on a shoulder 56 of the spark plug and press the spark plug in the

Spark plug shaft 20. By means of screws 53, 54, the clamping claw 50 in

Cylinder head 2 screwed. Thus, the spark plug 1 can be clamped in the spark plug well 20 without thread. It should be noted that the

Clamp 50 may be formed like a sleeve, or may be made in two parts. Furthermore, more than two protruding areas, preferably evenly distributed on the circumference of the clamping claw, may be provided.

It should also be noted that several spark plugs of a cylinder bank can be clamped by means of a suitably designed one-piece clamping claw. Otherwise, this embodiment corresponds to the previous embodiment, so that given there

Description can be referenced.

Claims

A spark plug for an internal combustion engine, comprising:  an insulator (7), and  a seat supporter (4) disposed at a portion of the insulator (7) and circumferentially surrounding the insulator (7), the seat supporter (4) being located closer to a combustion chamber side end than to a terminal side end of the ignition plug; Insulator (7) has a first circumferential shoulder (10) with a first diameter (D1), wherein on the combustion chamber side of the shoulder (10) is provided a combustion chamber side foot region (11) with a second diameter (D2),  wherein the seat support (4) has a maximum seat support diameter (S1), and  wherein the diameter (D2) of the combustion chamber side foot region (1 1) and the maximum outer diameter (S1) of the seat support (4) satisfies the equation D2 = t * S1, where 0.8> t> 0.5. Spark plug according to claim 1, characterized in that the seat body (4) is arranged at the combustion chamber end of the spark plug (1) and a length (L1) in the axial direction (XX) of the spark plug, which is less than or equal to a quarter of a maximum length (L ) of the spark plug in the axial direction. Spark plug according to one of the preceding claims, characterized in that 0.6> t> 0.55 and in particular 0.56. Spark plug according to one of the preceding claims, characterized in that the insulator (7) at an attachment-side end of the shoulder (10) has an annular recess (12) with a minimum third diameter (D3), wherein the third diameter (D3) is greater than the second diameter (D2) on the combustion chamber side foot area (1 1). Spark plug according to one of the preceding claims, characterized in that the third diameter (D3) on the annular recess (12) and the first diameter (D1) on the shoulder (10) satisfy the equation D3 = k * D1, where k is greater than or equal to is equal to 0.8. Spark plug according to Claim 5, characterized in that k lies between 0.8 and 0.9, in particular between 0, 8 and 0.85, and more preferably 0.82. Spark plug according to one of the preceding claims, characterized in that the spark plug is a thread-free spark plug. A spark plug according to any one of the preceding claims, further comprising a tightening nut (3) or a bayonet member for fixing the spark plug in a spark plug well (20). 9. Spark plug according to one of claims 1 to 7, further comprising a  Clamp (50) to clamp the spark plug in the spark plug well (20). 10. Spark plug according to one of the preceding claims, characterized  in that the insulator (7) has at least one flat in order to provide an anti-twist device for the spark plug.