EP2195895A1

EP2195895A1 - Spark plug

Info

Publication number: EP2195895A1
Application number: EP07843634A
Authority: EP
Inventors: Richard E. Callahan; Ellen M. Hively
Original assignee: Federal Mogul LLC
Current assignee: Federal Mogul LLC
Priority date: 2007-10-02
Filing date: 2007-10-02
Publication date: 2010-06-16
Also published as: EP2195895A4; KR20100072284A; WO2009045209A1; JP2010541178A; CN101868890A

Abstract

A spark plug is disclosed for igniting the air-fuel mixture in an internal combustion engine. The spark plug includes an electrode terminal extension pin, a firing electrode, a ground electrode, a sleeve insulator and an upper and lower insulator. The firing electrode is axially aligned with and in communication with the extension pin. The ground electrode is proximate the firing electrode to define a spark gap between the firing electrode and a first end of the ground electrode. The sleeve insulator surrounds the extension pin. The upper insulator surrounds an upper portion of the extension pin and is in contact with the sleeve insulator. The lower insulator surrounds the lower portion of the extension pin and is in contact with the sleeve insulator.

Description

SPARK PLUG

BACKGROUND OF THE INVENTION

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] NONE. Field of the Invention

[0002] The present invention relates to spark plugs for igniting combustion gases in a combustion chamber of an internal combustion engine. Related Art

[0003] Spark plugs are used in a variety of applications and are configured along with other accessory parts to fit within a given environment. For example, in a particular application the depth of the bore in the engine may require the use of a separate spark plug extension to connect the spark plug to the spark plug wire. While designs with accessory pieces meet their intended purpose many problems still exist. For example, spark plug designs having multiple pieces require complex training and cause logistic issues. Further, the more complex designs require retrofit instructions. Moreover, such designs having multiple pieces require field assembly and, thus, have a reduced reliability.

[0004] Therefore, it would be desirable to reduce the number of components necessary to install a spark plug in a given environment to reduce assembly complexity. Moreover, the new and improved designs should provide a more reliable spark plug.

SUMMARY OF THE INVENTION

[0005] In accordance with an aspect of the present invention a spark plug is provided for igniting the air-fuel mixture in an internal combustion engine. The spark plug includes a firing pin, a firing electrode, a ground electrode, a sleeve, an upper and lower insulator and conduit. The firing electrode is axially aligned with and in communication with the firing pin. The ground electrode is proximate the firing pin to define a spark gap between the firing pin and a first end of the ground electrode. The sleeve insulator surrounds the firing electrode. The upper insulator surrounds an upper portion of the firing electrode and is in contact with the sleeve insulator. The lower insulator surrounds the lower portion of the firing electrode and is in contact with the sleeve insulator. The conduit serves to contain and fasten the components.

[0006] In accordance with another aspect of the present invention, the spark plug includes an electrode contact button axially aligned and in contact with the firing electrode.

[0007] hi accordance with another aspect of the present invention, the spark plug includes a gasket disposed between the metallic electrode contact button and the firing electrode.

[0008] In accordance with still another aspect of the present invention, the metallic electrode contact button of the spark plug includes threads for engaging threads in the firing electrode.

[0009] In accordance with still another aspect of the present invention, the spark plug includes a metallic conduit surrounding the upper and lower insulators.

[0010] In accordance with still another aspect of the present invention, the spark plug includes an end bushing secured to an end of the shell for connecting an electrical conductor to the metallic electrode contact button.

[0011] In accordance with still another aspect of the present invention, the upper insulator has a plurality of portions having different diameters.

[0012] In accordance with still another aspect of the present invention, the lower insulator has a plurality of portions having different diameters.

[0013] In accordance with still another aspect of the present invention, the upper insulator includes a cavity for receiving a first end of the sleeve insulator.

[0014] hi accordance with still another aspect of the present invention, the lower insulator includes a cavity for receiving a second end of the sleeve insulator.

BMEF DESCRIPTION OF THE DRAWINGS

[0015] These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawings, wherein:

[0016] Figure 1 is a cross-sectional view through the spark plug, in accordance with an embodiment of the present invention;

[0017] Figure 2a is cross-sectional view of an internal portion of the spark plug, in accordance with an embodiment of the present invention;

[0018] Figure 2b is an end view of the spark plug, in accordance with an embodiment of the present invention; and [0019] Figure 3 is a cross-sectional view of the insulator of the spark plug, in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] Referring now to Figure 1, a cross-sectional view of an industrial spark plug 10 is illustrated, in accordance with an embodiment of the present invention. Industrial spark plug 10 includes a metal conduit 12. Contained within metal conduit 12 is a lower assembly 14 and an upper assembly 16. Lower assembly 14 and upper assembly 16 are electrically connected through an electrode terminal extension pin (ETEP) 20. ETEP 20 is surrounded by a sleeve insulator jacket 22. Metal conduit 12 is made of a metal material such as stainless steel or some similar alloy of steel. Jacket 22 is made of a non-conducting material such as a silicone rubber or polymer.

[0021] A bushing 18 is connected at a first bushing end 24 to metal conduit 12 by welding or other attachment means. At the other end 26 of bushing 18 are a plurality of threads 28. Threads 28 are for connecting bushing 18 to a spark plug wire (not shown). As conventionally known, the spark plug wire is connected to an energy source for supplying a voltage to the spark plug.

[0022] ETEP 20 includes a first end 28 having a plurality of threads and a second end 30 having a plurality of threads. First end 28 of ETEP 20 is threaded into a terminal stud 32, and end 30 is threaded into an electrode contact button 34. Terminal stud 32 and electrode contact button 34 are generally made of an aluminum-nickel alloy. Terminal stud 32 and electrode contact button 34 prevent combustion gases from entering and passing through metal conduit 12.

[0023] Referring now to Figures 2a and 2b, lower assembly 14 will now be described in further detail, in accordance with an embodiment of present invention. Assembly 14 is the firing end of spark plug 10. In other words, an applied high voltage pulse is carried to subassembly 14. Subassembly 14 includes a lower insulator 50 for preventing the high voltage pulse supplied to spark plug 10 from leaking between ETEP 20 and conduit 12. Lower insulator 50 is typically made of alumina or a similar material. Lower insulator 50 is contained within a lower shell 52. Lower shell 52 has a first end 54 that includes a plurality of threads that engage a bore in an engine block (not shown). Lower insulator 50 is placed in lower shell 52 and has a lower shoulder 53 that is pressed against a seat 55 in shell 52, A second end 56 of lower shell 52 engages lower insulator 50 at an upper shoulder 58 of insulator 50 to capture the insulator. More specifically, insulator 50 is retained within lower shell 52 by crimping end 56 over shoulder 58. An annular groove 57 is disposed in shell 52 to define a narrowed wall section 59. Narrowed wall section 59 is heated and pressure is applied to the ends of shell 52 to cause wall 59 to collapse and expand outward. The collapsed wall section 59 causes shell 52 to decrease in length. The decreased length of shell 52 creates a predefined pressure on lower insulator 50 holding the insulator firmly in place within the shell 52.

[0024] A firing electrode 60 is disposed near first end 54 of shell 52. ETEP 20 is connected to and supplies voltage to firing electrode 60 through a spring and suppressor (radio frequency) 64. A ground plate 66 surrounds firing electrode 60 and is welded or otherwise attached to end 54 of shell 52. As will be described hereinafter, a spark gap is defined by the clearance between firing electrode 60 and ground plate 66. [0025] An end view of firing electrode 60 and ground plate 66 is shown in Figure 2b. As shown in Figure 2b, ground plate 66 includes a plurality of prongs 70 which extend inwardly toward firing electrode 60. The end of each of the inwardly extending prongs 70 and firing electrode 60 form the spark gap over which a spark is created.

[0026] Referring now to Figure 3, upper insulator assembly 16 is further illustrated, in accordance with an embodiment of the present invention. Upper insulator assembly 16 includes an upper insulator 90 which has a first end 92. Near first end 92 is an annular groove 94. Annular groove 94 is configured to receive a sealing gasket (not shown). The sealing gasket seals and positions upper insulator 90 within conduit 12. Near the other end 96 of upper insulator 90 is a series of stepped-down portions having progressively smaller diameters. More specifically, upper insulator 90 includes a first diameter portion 98, a second diameter portion 100, a third diameter portion 102, and a fourth diameter portion 104. The inner diameter of portions 100, 102 and 104 are the same dimension, and the inner diameter of portion 98 is larger than the diameter of portions 100, 102 and 104. Further, upper insulator 90 includes a transitional region or seat 106 that is configured to receive a sealing gasket (not shown) to seat and sleeve 22 thereagainst.

[0027] During assembly upper insulator 90 is positioned within conduit 12 and moved towards lower assembly 14 until sleeve 22 contacts seat 106. The contact of sleeve 22 and seat 106 prevents further movement of upper insulator 90 toward lower insulator 50. Bushing 18 is then placed into conduit 12 until the interior walls of bushing 18 contact the exterior walls of insulator 90 at end 96. Bushing 18 is then welded or otherwise mechanically fastened to conduit 12 to secure upper insulator 90 within conduit 12. [0028] The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and do come within the scope of the invention. Accordingly the scope of legal protection afforded this invention can only be determined by studying the following claims.

Claims

What is claimed is:

1. A spark plug comprising: an electrode terminal extension pin; a firing electrode axially aligned with and in communication with the extension pin; a ground electrode proximate to the firing electrode to define a spark gap between the firing electrode and a first end of the ground electrode; a sleeve insulator surrounding the firing electrode; an upper insulator surrounding an upper portion of the extension pin and in contact with the sleeve insulator; and a lower insulator surrounding a lower portion of the extension pin and in contact with the sleeve insulator.

2. The spark plug of claim 1, further comprising a metallic contact button axially aligned and in contact with the firing electrode.

3. The spark plug of claim 1, further comprising a gasket disposed between the metallic contact button and the firing electrode.

4. The spark plug of claim 2, wherein the metallic contact button includes threads for engaging threads in the firing electrode.

5. The spark plug of claim 2, further comprising a metallic shell surrounding the upper and lower insulators.

6. The spark plug of claim 5, further comprising an end bushing secured to an end of the shell for connecting an electrical conductor to the metallic contact button.

7. The spark plug of claim 1, wherein the upper insulator has a plurality of portions having different diameters.

8. The spark plug of claim 1, wherein the lower insulator has a plurality of portions having different diameters.

9. The spark plug of claim 1, wherein the upper insulator includes a cavity for receiving a first end of the sleeve insulator.

10. The spark plug of claim 1, wherein the lower insulator includes a cavity for receiving a second end of the sleeve insulator.