WO1994006183A1

WO1994006183A1 - Spark plug terminal

Info

Publication number: WO1994006183A1
Application number: PCT/US1993/008261
Authority: WO
Inventors: William J. Hallauer; William A. Barrett; Alan H. Bilger; Duane R. Hammer; Donald C. Kin
Original assignee: Allied-Signal Inc.
Priority date: 1992-09-08
Filing date: 1993-09-02
Publication date: 1994-03-17

Abstract

A connector for joining a wire (16) with a sleeve (22) thereon to the center electrode (24) of a spark plug (14). The sleeve (22) has a ring (58) thereon which engages a serrated surface (36) on a center electrode to provide an audible and mechanical indication when an electrical connection has occured which will meet desired operational standards.

Description

SPARK PLUG TERMINAL This case relates to a connection for joining a wire to the terminal of a center electrode for a spark plug through which an electrical signal is communicated to effect a spark in a combustion chamber.

It has long been recognized that in some environments an electrical connection between a wire and a terminal needs to be protected to prevent shorting and contamination which can produce deterioration which affect the communication of an electrical signal through the connection. This is especially true in the communication of electrical energy to properly operate a spark plug for an internal combustion engine. U.S. Patent 3,002,126 discloses an example of the boots that have been used to prevent contamination from reaching the terminals of connections. In an effort to provide for a seal between the boot and spark plug, the tolerances between the boot and ceramic insulator have been reduced such that in some instances an accurate connection does not occur since the terminal and center electrode are not fully engaged. In addition, high temperatures generated by many internal combustion engines can adversely affected the elastomeric material most commonly found in many boots through a bond formed by the silicon in the elastomeric material and ceramic insulator of a spark plug. Thereafter, when the wire and boot are removed from the spark plug, the boot can be damaged. Some efforts have been directed in ways to assist in the removal of the boot from a spark plug such as the combined shield and boot disclosed in U.S. Patent 4,671,586. In the present invention, we have developed a connection through which the terminal member of a center electrode of a spark plug is joined to a wire and protected by a boot connected to the wire which engages a ceramic insulator of the spark plug. The terminal member which extends from the center electrode has a cylindrical body with an annular flange on a first end which engages the ceramic insulator and a conical surface on a second end. The cylindrical body has a serrated surface that substantially extends from the flange to the conical surface. A sleeve member has a first end attached to the wire and a second end that surrounds the cylindrical body and engages the flange on the terminal member. The conical surfaces on the terminal member and the second end of the boot align the sleeve and boot with the center electrode of the spark plug. A resilient ring which surrounds the sleeve has a series of projections that extend through corresponding slots in the sleeve member to progressively engage the serrated surface on the terminal member as the second end of the sleeve is moved toward the flange. On movement of the sleeve and boot toward the flange on the terminal member, the engagement of the resilient ring with the serrated surface provides both an audible sound and vibration to inform a person that an electrical connection has been completed between the wire and center electrode to assure that an electrical flow path is created for providing an electrical signal to a combustion chamber.

It is an object of this invention to provide a connection for a spark plug which includes structure to audibly and mechanically inform a person that an electrical connection has been made between a wire and a center electrode.

It is a further object of this invention to provide an electrical system with a connection having a plurality of locking positions to retain a sleeve attached to a wire on a terminal member of a center electrode of a spark plug.

These and other advantages of the proposed connection should be apparent from reading this specification while viewing the drawings wherein:

Figure 1 is a schematic illustration of a spark plug located in a cylinder head of a vehicle with a center electrode connected to a wire according to the principles of the present invention; Figure 2 is a schematic view of a sleeve clip attached to the wire of Figure 1; and

Figure 3 is a perspective view of the resilient member for retaining the sleeve clip on the terminal member of the center electrode of Figure 1. The ignition system 10 illustrated in Figure 1 has wire 16 through which an electric signal is supplied to a spark plug 14 located in a combustion chamber 12 of an engine. A boot 18 which surrounds an insulated cover 17 on wire 16 protects a joint 20 created between spark plug 14 and sleeve clip 22 on the end of wire 16 from contamination or exposure to the surrounding environment.

The spark plug 14 has a center electrode system 24 with a first end 26 that extends into combustion chamber 12 and a terminal member 28 that engages the sleeve clip 22.

Terminal member 28 has a cylindrical body 30 with an annular flange 32 on a first end that engages face 44 on ceramic insulator 34 which surrounds the center electrode system 24 and a conical surface 35 on a second end. Conical surface 35 forms a relative gradual transition from the peripheral diameter on the second end to a serrated surface 36 on cylindrical body 30. The serrated surface 36 which substantially extends from the conical surface 35 to annular flange 32 has a plurality of annular grooves 38, 38'...38ⁿ separated by corresponding lands 40, 40'...40ⁿ. The depth and width of the annular grooves 38, 38'...38ⁿ are approximately 1/100 of an inch or .02 cm. which has been determined to be sufficient to adequately function in a desired manner as hereinafter described to create an audible signal.

The ceramic insulator 34 has a substantially cylindrical body that extends from conical surface 46 adjacent face 44 to end 48 located outside of metal shell 50. Metal shell 50 has a flange 52 that engages a rib on cylindrical body to form a seal to prevent communication between combustion chamber 12 and the surrounding environment. The cylindrical body has a series of grooves 42, 42'...42ⁿ located adjacent conical surface 46 to increase the peripheral surface area and thereby reduce the possibility of an external electrical flow path being created which may adversely affect the communication of an electrical signal through the center electrode system 24. Conical surface 46 has a transition angle from end 44 which is about fifty percent greater than that of conical surface 35 on terminal member 28 to provide a guide surface for the boot 18 to initially center sleeve clip 22 on conical surface 35. The width to the depth of the grooves 42, 42'...42ⁿ is about 2:1 while the width of lands 43, 43'...43ⁿ is about one half of the depth. The surface area of lands 43, 43'...43ⁿ is sufficient to form sufficient sealing surface with boot 18 to prevent communication from the environment to joint 20 while allowing removal from the ceramic insulator 34 without damage. As best shown in Figure 2, sleeve clip 22 is attached to the end of wire 16 by a groove crimp 51 to engage and hold conductive strands 52 of wire 16 against protective cover 17. A resilient ring 58, as best shown in Figure 3, which surrounds sleeve clip 22 has a series of projections 60, 60' that extend through a plurality of radial slots 54, 54' located in the sleeve clip 22 about midway between crimp 51 and end 56. The projections 60, 60' progressively engage serrated surface 36 to a number of locking positions for retaining sleeve clip 22 on terminal member 28 and thereby assure that an electrical connection is created between strands 52 of wire 16 and center electrode 24.

During attachment wire 16 to spark plug 14, initially annular bead 19 on the end of boot 18 engages conical surface 46 on ceramic insulator 34 to align spring clip 22 with conical surface 35 on terminal member 30 and thereafter end 56 of the sleeve clip 22 engages land 40 on terminal member 30 to establish an electrical flow path between strands 52 and the center electrode 24. As the end 56 moves toward flange 32, the projections 60, 60' progressively moves from groove 38, 38'...38ⁿ to create an audible sound and vibration until end 56 engages flange 32.

Through this invention, an operator is informed by both an audio and a mechanical signal when wire 16 is attached to spark plug 14 and an electrical connection 20 has been created to sufficiently meet a desired operational standard.

Claims

CLAIMS We claim:

1. In an ignition system having a spark plug with a center electrode surrounded by a ceramic insulator, a wire connected to a control member, a connection through which said center electrode is joined to said wire and a boot connected to said wire and engaging said ceramic insulator for protecting said connection from the environment, said connection being characterized by a terminal member extending from said center electrode, said terminal member having a cylindrical body with an annular flange on a first end that engages said ceramic insulator and a conical surface on a second end, said cylindrical body having a serrated surface that substantially extends from said flange to said conical surface; a sleeve member which surrounds said cylindrical body having a first end connected to said wire and a second end that engages said flange, said sleeve member having a plurality of radial slots located adjacent said second end; and a resilient ring surrounding said sleeve having a series of projections that extend through said slots to progressively engage said serrated surface to retain said second end in engagement with said flange and assure that an electrical connection is created between said wire and center electrode to assure an electrical flow path is created through which an electrical signal is communicated to a combustion chamber.

2. In the ignition system as recited in claim 1 wherein said connection is further characterized by an annular crimp located on said sleeve through which said wire is joined to said sleeve.

3. In the ignition system as recited in claim 2 wherein said connection is further characterized by said conical surfaces for aligning said sleeve and boot with respect to said terminal and ceramic insulator.

4. In the ignition system as recited in claim 3 wherein said engagement of said projections on said resilient ring with said serrated surface creates an audible signal which provides an indication of the engagement of said sleeve with said terminal member.

5. In the ignition system as recited in claim 4 wherein said engagement of the projections on said resilient ring with said serrated surface creates a vibration which provides an operator with a mechanical indication of the engagement of the sleeve with the terminal member.

6. In the ignition system as recited in claim 5 wherein said ceramic insulator has a plurality of equally spaced annular grooves separated by a series of annular ribs, said groves extending from a conical surface adjacent an end face, said conical surface guiding said boot onto said ceramic insulator and over said annular grooves, said boot engaging said ribs to form a seal to prevent communication of contamination to said connection.