This invention relates to an ignition coil assembly 5 for internal combustion engines.

Current conventional ignition coil assemblies for internal combustion engines, in particular those for vehicular applications, include a sizable steel laminated

10 core and associated primary and secondary coil assemblies encased within a fairly thin electrically insulating thermoplastic housing. To mount or permanently fix the coil assembly to the engine or its environs, it is known to provide mounting holes through the core, and sometimes

15 through the surrounding housing also, as is shown in U.S.

Patent No. 4,763,094. This limits the options for placement of the coil assembly within the engine compartment. Specifically, the ignition coil assemblies mentioned above must be mounted on grounded surfaces to eliminate the

20 possibility of electric shock. Further, it has been noted that the differences in thermal expansion coefficients between the housing and laminated core may give rise to stresses in the housing that can affect the waterproof integrity of the assembly and/or lead over time to the

25 propagation of hairline fractures within the housing.

In instances where the core laminations would otherwise be externally exposed, such as in the four tower coil design shown in U.S. Patent No. 4,763,094, it is also know to 30 provide a soft water-proof layer of insulating tape or like material placed across the inner exposed surfaces of the » C-shaped laminated cores. This is an expensive procedure to implement in actual mass production of the ignition coil <n assemblies. Utilisation of the water-proof tape also

35 necessitates adding another operation to the manufacture of the ignition coil assembly on the production assembly line.

The present invention is directed to all the foregoing concerns. Further, the present invention is directed to providing flexibility of manufacturing techniques to allow the same basic coil design to be used for distributor-based and distributorless ignition systems.

Ignition coil assemblies of the prior art are dedicated by design to either distributor or distributorless ignition systems. Distributorless ignition systems typically require high voltage output terminals equal in number to the number of cylinders of the particular engine, for example, a 4- cylinder engine would require a four tower ignition assembly like that disclosed in U.S. Patent No. 4,763,094. This dedication to a particular ignition assembly design requires respective dedication of the production assembly line machinery to distributor or distributorless production systems.

In view of the foregoing, this invention contemplates providing an ignition coil assembly for internal combustion engines having increased overall reliability and precluding any possibility of water ingress to the internal components of the ignition coil and prevents poor performance of the coil assembly while increasing overall reliability.

The invention further contemplates an ignition coil assembly having a housing completely enshrouding the primary and secondary coil assemblies and core member and including integrally moulded mounting members-arranged on the outer perimeter of the housing in non-interfering relationship with the internal coil/core assemblies.

The ignition coil assembly embodying the present invention includes an "I" shaped core made of laminated steel strips, a primary bobbin with insulation displacement terminals, a primary coil, a secondary bobbin with integrally connected high voltage tower terminals, a secondary coil, high voltage towers, and an ignition

assembly housing with integrally formed mounting lugs and a laminated C-shaped core. The primary coil assembly is placed within the secondary coil assembly and both are then placed within the inner opening of the C-shaped core. The primary connector assembly is then placed over a lip portion of one side of the housing and the primary connector assembly leads then engage the insulation displacement terminals contained on the primary coil assembly.

The high voltage towers are then fastened into the terminals of the secondary coil. A potting material is subsequently introduced into the inside of the ignition coil assembly housing to encapsulate and electrically insulate the inner components of the ignition coil subassembly.

An alternative embodiment utilises a laminated core which has been encased in an elastomer such as a rubber modified polypropylene and is not moulded into the housing assembly.

By making relatively minor modifications in the design and manufacture of the ignition coil assembly embodying the invention both distributor-based and distributorless igni¬ tion systems may be provided.

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective, partially sec- tioned, partially exploded view of an ignition coil assembly according to one embodiment of the invention;

Figure 2 is a side, partially sectioned, exploded view of the ignition coil assembly shown in Figure 1 and with potting material and high voltage towers removed; Figure 3 is a perspective view of a C- shaped laminated core totally encased in a rubber insulation material according to the embodiment shown in Figures 1 and 2;

Figure 4 is a perspective view of a four tower ignition coil assembly of the prior art;

Figure 5 is an enlarged, perspective, par¬ tially exploded view of the primary bobbin, primary coil, primary terminals and primary terminal receptacle of the present invention as shown in Figure 1;

Figure 6 is a sectioned side view taken along lines 6-6 of Figure 5 and illustrating the insulation displacement terminal and a portion of the primary coil inserted within;

Figure 7 is a perspective, exploded view of an alternative embodiment of the present invention show¬ ing a primary connector assembly and a bypass electrical connection utilised in a distributor-type ignition coil assembly;

Figure 8 is a segmented top view of an al¬ ternative embodiment of the primary connector assembly illustrating a bypass electrical connection and the dovetail locking and receiving sections; and Figure 9 shows an alternative embodiment of the present invention in partial cross-section wherein the core is moulded within the coil assembly housing.

Referring now to Figures 1, 2 ^" and 3, an ignition coil assembly 2 of the present invention includes a housing 4 having a plurality of identical mounting members 6, 8 and 10 all disposed on the exterior of the housing and moulded integrally with the housing. Elongated metal bushings 12 are positioned within the centre of the mounting members to facilitate secure mounting of the ignition coil assembly within the engine compartment.

A dove tail receiving section 14 is also integrally moulded onto the outside of the housing. The dove tail receiving section 14 securely receives and holds in place a corresponding dove tail locking section 16 configured on the primary connector assembly. The legs 18 on each side of locking section 16 are in slip fit engagement with and

within the respective channels of the receiving section 14.

A steel laminated C-shaped core 20 is located within the housing. Core 20 is provided with an inner open cavity 22 within which is nested primary and secondary coil assemblies designated 24 and 26, respectively. The secondary coil assembly 26 includes bobbin 28. A coil 30 is wound around bobbin 28 with the ends of the coil terminating at the secondary terminal boxes 32. The secondary coil end portions are soldered to the secondary terminals 34 which are press fit into the secondary terminal boxes 32.

Referring now to Figures 1, 2 and 5, the primary coil assembly 24 is seen to comprise a laminated I-shaped core 36 moulded within a bobbin 38. A primary terminal receptacle 40 is an integrally moulded part of the bobbin 38 at one end thereof and includes a terminal seat portion 42. A second seat 44 extends from the bobbin 38 at its other end. Each seat 42,44 is adapted to mate with a first inner recess 46 and a second inner recess 48, respectively, formed on the core 20 as shown in Figure 3.

For assembly purposes, to assure the coil assembly is oriented properly within the case, the seats 42,44 are laterally offset from one another as are the recesses 46,48. Thus, each functions as a piece orientation feature just as the key and keyway 52,54, respectively of the core and housing, as explained in detail below.

Figure 3 shows a laminated C-shaped core 20 encased in a rubber modified polypropylene shell 50. The C-shaped laminated core is adapted to be received and slip fit inside the lower portion of the housing. The rubber modified polypropylene 50 such as sold by A Schulman, Inc. (USA) under the trademark PolytropeR (specification Nos. TPP 503, 504, 514, 517 and 524) and also sold by Advanced Elastomeric Systems (USA) under the trademark SantopreneR and VistaflexR (TPR), specification Nos. 123-60 and 9203-54W900,

respectively, is a preferred encasement material because it acts as a compliant, compressible, stress-relief layer between the metal C-core 20 and the housing 4. The surface chemistry of the encasement material must be non-bonding or non-reactive with the housing and potting material to allow for movement of the materials with respect to one another as well as provide relief from the effects of differing coefficients of expansion of the various materials. This non-bonding chemistry prevents cracking during thermal cycling or during extended time periods at elevated temperatures that ignition coil assemblies are commonly subject to.

A keyway 52 is positioned inside an inner portion of the housing 4 and a mateable key 54 is provided on the outside portion of the core and adapted to engage the keyway 52 of the housing 4.

As shown in Figures 5 and 6, the primary bobbin 38 also has disposed above the primary terminal seat 42 a primary terminal receptacle 40 which.is configured to receive a pair of insulation displacement terminals 56. A coil 58 is wound around the bobbin 38 with the terminating ends 60 of the coil 58 placed within the insulation displacement terminals 56 and confined within pairs of oppositely disposed, inverted V-shaped slots 62.

The terminating ends 60 of the primary coil 58 thus extend the length of the cavity within which the displacement terminal resides. The terminals 56 are U- shaped and include a spring biasing arm 64 which engages the leads 60. The terminals 56 are held in the cavity by burrs 66 on the sides of the terminals 56. Thus when the insulation displacement terminals 56 are positioned inside the primary terminal receptacle cavity 68, the terminal will be wedged in place against the sidewalls 68 of the cavity. Each insulation displacement terminal 56 includes inverted V-shaped slots 62 or coil receiving openings such that when

the terminal is forced down into cavity 70 the primary coil terminating ends 60 will be engaged.

As shown in Figure 6, the primary coil terminating ends 60 extend through both the primary terminal receptacle 40 and the insulation displacement terminals 56. As the coil receiving opening 62 is brought down upon the primary coil end portion 60, the insulation material deposited entirely along on the primary coil 58 is shaved off and direct elec¬ trical contact is made between the primary coil terminating ends 60 and the insulation displacement terminal 56.

The primary connector assembly 74 as shown in Figures 1 and 2 is made of an electrically insulating material. It has an electrode insulation segment 76 and a receptacle portion 78. Electrode insulation segment 76 is constructed to overlap a lip portion 80 of the housing 4 and extend down into the housing. Leg 18 is spaced from the receptacle portion 78 to provide a gap 82 slightly greater in width than the thickness of the housing such that the connector assembly will slip over the housing until the lip 80 engages the connector assembly at the bend 84. As earlier described the primary connector assembly 74 also includes a dove tail locking section 14 for use in affixing the primary connector assembly to the housing. Whereas the gap 82 retains the assembly 74 from outward separation from the housing, the locking section 14, specifically channel members 86 preclude relative lateral displacement.

As shown in Figure 7, electrical leads 88 and 90 travel through the electrode insulation segment 76 and the receptacle portion 78. The electrical leads 88,90 have at their end portions, openings 92,94 which facilitate a direct electrical connection between the end portion of the electrical leads 88,90 and the primary coil 58.

As is conventional lead 88 receives ignition system control data from an onboard ignition control system and second primary connector assembly electrical lead 90

receives 12 volt input from the vehicle battery system.

To assemble the coil assembly 2, the primary coil assembly 24 is inserted within secondary coil assembly 26. Separately the core 20 is inserted within housing 4. Then the combined coil assembly 24,26 is placed within the cavity 22 of core 20 such that primary terminal seats 42 and extension seat 44 of the primary bobbin 38 rest within recesses 46 and 48, respectively of C-shaped core 20. The secondary coil assembly 26 and the primary coil assembly 24 are thus supported within the inner open cavity 22 of the C- shaped laminated core 20.

Towers 96 are then threaded into secondary terminals 34. A moulding resin 98 is subsequently introduced into the inner portion of the housing after all components have been assembled and the moulding resin covers and electrically insulates the entire ignition coil assembly.

Figures 7 and 8 show an alternative embodiment of the present invention adapting an ignition coil assembly suitable for use with a distributorless ignition system to an ignition coil assembly suitable for use with a distributor-based ignition system. Removal of one high voltage tower 96 and the addition of a slightly modified primary connector assembly effectively transforms the ignition coil assembly to a distributor type coil for use in a conventional internal combustion engine. Specifically, the modified primary connector assembly of this embodiment utilises a bypass member 108 which connects the secondary terminal 34 to the second electrical lead 88 which is the positive terminal of the primary coil. Electrical lead 88 is at low voltage, i.e. 12 volts for the conventional 12 volt system and thus provides a virtual ground. Fastening screw 110 secures bypass electrical connection 108 to terminal 34.

Figure 9 shows a further embodiment of the present

invention wherein the core 20 is moulded entirely within the inner and outer walls 100,102 of the housing. The core 20 entirely encased within the housing is provided with a first inner recess 104 and a second inner recess 106 adapted to mate with the terminal seat portion 42 and the second seat 44 of the bobbin 38. The corresponding position of the inner recesses is identical to that shown in Figure 3. Alternatively, a rubber coated core, not shown, may be insert moulded between the inner and outer walls of the assembly housing 2.