Mounting for Ignition Module

Various methods and means have been used in the past for fastening the coil module onto a leg portion of a flux carrying armature or core.

In one such method, the coil module is bonded onto the core leg by using an epoxy resin bonding agent. The major drawback of this technique is that it does not lend itself to automated processing and the application of the epoxy for effective bonding is time consuming.

Other methods have involved the use of metallic mounting clips especially adapted to be affixed to the core at their inner ends and with an angle or bend at their upper ends to capture and hold the module in fixed position on the core leg. Among the drawbacks of using these metal clips, is that they tend to absorb some of the electromagnetic energy generated in the coil and reduce the kilovolt output of the ignition coil. Moreover, such clips must be fastened to the core and to the module and thus they are not readily adaptable to automated assembly techniques.

The principal effect of this invention is to provide a novel, simple, economical and highly effective means for fastening a coil module to a flux carrying core.

Another object of this invention is to provide means for fastening a coil module to a flux core which is adaptable to automated assembly procedures.

The above and other objects or advantages of this invention will be more readily appreciated by a reading of the following description read in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a coil/core assembly of the type used in magneto ignition systems;

FIG. 2 is a perspective view of the core element of the assembly;

FIG. 3 is a perspective view of the coil module portion of the assembly;

FIG. 4 is a perspective view of the retaining pin used in the assembly;

FIG. 5 is a partial side-elevational view illustrating the relationship between the various parts of the assembly;

FIG. 6 is a partial front-elevational view of the same parts as shown in FIG. 5, and

FIG. 7 is an elevational view of the assembly partly in section which illustrates the geometric relationship of the components.

Referring in detail to the drawings, in FIG. 1 an ignition coil/core assembly is shown generally at 8. The assembly comprises an E-shaped, multi-leg core 10 and an ignition coil module 12 mounted on the core.

The core 10, also shown in FIG. 2, comprises a laminated structure of sheet metal plates fastened together, such as by riveting or the like (not shown). The core includes a cross-bar portion 15 and three parallel leg portions 16, 18 and 20 extending outwardly therefrom and the terminal ends of the legs are radiused. The core provides a flux path for magnet poles rotated past the core legs in the conventional manner. At a point adjacent the cross-bar 15, the leg 16 includes a circular cutout or recess 22 to assist in the assembly procedure, as will hereinafter be more fully described.

The module 12 comprises a synthetic plastic shell of generally rectangular configuration 30. The shell is generally a premolded polypropylene material into which is fitted in the primary and secondary windings of an ignition coil. Also, an electronic control circuit may be fitted into the shell which is then filled with a dielectric potting compound. An opening or chimney 32 extends axially through approximately the central portion of the coil. This opening is generally rectangular in cross-section and is dimensioned to be slightly larger than the cross-section of the core leg 18 to provide sufficient clearance for ease of assembly. Adjacent the upper or inner end of the module 12, as disposed on the core 10, is an outwardly extending portion 38 which is provided with a concave surface or recess 34. The recess is approximately one quarter of a cylinder having its longitudinal axis d (FIG. 5) disposed transversely of the longitudinal axis e (FIG. 7) of the chimney 32. The recess 34 includes an annular groove 36 adjacent one end.

As best shown in FIG. 7, the concave cylindrical surface 34 provided on the module 12 and the concave cylindrical surface 22 formed in the upper, inner edge portion of the leg 16 are complementary portions of a cylinder. The recess 22 is approximately semi-cylindrical and recess 34 is approximately a quarter of a circle.

When the upper surface of the module 12 is disposed in contact with the cross-bar 15 of the core, the two arcuate surfaces define a partial cylindrical opening of about 270 degrees in circumference with a predetermined diameter, slightly less than the diameter of a retaining pin 14.

The pin 14 is a resilient member of generally cylindrical cross-section and, as shown, has an ogival tip portion 24 at one end and an annular flange 26 which extends radially outward of the cylindrical surface adjacent the other end 28 of the pin. The pin may be solid or, as illustrated in FIG. 4, may be tubular in cross-section. The leading edge of the flange 26 is of tapered or conical configuration to facilitate insertion of the locking pin in the opening defined by the recess 22 and 34. The pin 14 may be made of any suitably resilient material and, for example, may be molded of a synthetic plastic material, including suitable thermoplastic or thermosetting materials, such as a polyester or phenolic resin. Preferably, the molding composition includes a filler or fiber content such as glass or graphite fibers or mineral particles for enhanced strength. The fiber or mineral content of the composite is preferably made relatively high and the wall thickness of the tubular pin is selected such that the pin will have a high modulus of elasticity which will remain essentially constant for the expected life of the coil.

To assemble the coil/core structure of this invention, coil module 12 is telescopically fitted onto the middle leg 18 of the core 10. The upper end of the module is pressed against the cross-bar 15 of the core and the locking pin 14 is axially inserted into the opening defined by the spaced opposed, cylindrical surface portions 22 in the core and 34 on the module. A rod-like tool may be used to drive the pin into its fully locked position, as best shown in FIG. 5, with the flange 26 fitted into groove 36 so that the pin will be locked in a fixed axial position on the assembly. The diameter of the pin 14 is somewhat greater than the diameter of the partial cylinder defined by the two surfaces 22 and 34 so that the pin will be radially compressed when inserted therebetween. Radial compression of the pin results in an upwardly and inwardly directed force vector a (FIG. 7). This diagonal vector is the resultant of two right angled components b and c which are respectively parallel to axis e of the chimney 32 and perpendicular to the axis e. These components ensure that the core will remain axially and transversely fixed on the center leg 18 of the core 10.

This construction, moreover, permits relatively easy assembly of the coil module onto the core by the simple expedient of inserting the resilient locking pin in the cylindrical opening defined by partial cylindrical surfaces 22 and 34.