High voltage ignition coil with improved insulating characteristics

Abstract

An ignition coil has a ferromagnetic core with a primary coil surrounding a first portion of the ferromagnetic core and a secondary coil surrounding the second portion of the ferromagnetic core. The secondary coil is wrapped around a bobbin. The bobbin has an interior receiving the second portion of the ferromagnetic core. A form is interposed between the secondary coil and the second portion of the ferromagnetic core. The form extends longitudinally along the second portion of the ferromagnetic core. The form is of a non-ferrous metal material.

Claims

1. An ignition coil comprising: a ferromagnetic core; a primary coil surrounding a first portion of said ferromagnetic core: a secondary coil surrounding a second portion of said ferromagnetic core, said secondary coil being wrapped around a bobbin, said bobbin having an interior that receives the second portion of said ferromagnetic core therein; and a form interposed between said secondary coil and the second portion of said ferromagnetic core, said form extending longitudinally along the second portion of said ferromagnetic core, said form being of a non-ferrous metal, said form being of a generally tubular shape, said tubular shape having a split extending longitudinally therealong so as to interrupt a circularity of said tubular shape.

2. The ignition coil of claim 1, said form extending substantially along the entire length of said bobbin.

3. The ignition coil of claim 1, said bobbin having an inner wall facing the second portion of said ferromagnetic core, said form being affixed to said inner wall of said bobbin.

4. The ignition coil of claim 1, said form affixed to the second portion of said ferromagnetic core within the interior of said bobbin.

5. An ignition coil comprising; a ferromagnetic core; a primary coil surrounding a first portion of said ferromagnetic core; a secondary coil surrounding a second portion of said ferromagnetic core, said secondary coil being wrapped around a bobbin, said bobbin having an interior that receives the second portion of said ferromagnetic core therein; a form interposed between said secondary coil and the second portion of said ferromagnetic core, said form extending longitudinally along the second portion of said ferromagnetic core, said form being of a non-ferrous metal; and a frame affixed to an exterior of the second portion of said ferromagnetic core, said frame being of a non-metallic material.

6. The ignition coil of claim 1, said ferromagnetic core having a generally square or rectangular shape, said primary coil positioned on a side of said ferromagnetic core, said second coil positioned on opposite side of said ferromagnetic core.

7. The ignition coil of claim 1, further comprising: a housing having an interior, said ferromagnetic core and said primary coil and said secondary coil and said form being received within the interior of said housing.

8. An ignition coil comprising; a ferromagnetic core having a generally rectangular configuration; a primary coil extending over one side of said ferromagnetic core; a bobbin positioned over an opposite side of said ferromagnetic core, said bobbin having a plurality of bays therein, said bobbin having inner wall adjacent to the opposite side of said ferromagnetic core; a second coil received in said plurality of bays of said bobbin; and a form interposed between said secondary coil and the opposite side of said ferromagnetic core, said form being of a non-ferrous metallic material, said form being of a generally tubular shape, said tubular shape having a split extending longitudinally therealong so as to interrupt a circularity of said tubular shape.

9. The ignition coil of claim 8, said form extending substantially along an entire length of said bobbin.

10. The ignition coil of claim 8, said bobbin having an inner wall facing the opposite side of said ferromagnetic core, said form being affixed to an inner wall of said bobbin.

11. The ignition coil of claim 8, said form being affixed to the opposite side of said ferromagnetic core and within an interior of said bobbin.

12. The ignition coil of claim 8, further comprising: a frame affixed to an exterior of the opposite side of said ferromagnetic core, said frame being of a non-metallic material.

13. The ignition coil of claim 8, further comprising: a housing having an interior, said ferromagnetic core and said primary coil and said secondary coil and said bobbin being received within the interior of said housing.

14. The ignition coil of claim 8, said form extending longitudinally in concentric relation with said opposite side of said ferromagnetic core.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) FIG. 1 is a side elevational view of the ignition coil of the present invention with the ignition coil housed in a housing.

(2) FIG. 2 is a side elevational cross-sectional view showing one embodiment of the ignition coil of the present invention.

(3) FIG. 3 is an end view of one embodiment of the ignition coil of the present invention.

(4) FIG. 4 is an end view of an alternative embodiment of the ignition coil of the present invention showing the form as isolated from the ferromagnetic core.

(5) FIG. 5 is an end view of an alternative embodiment of the ignition coil of the present invention showing the form adjacent to the ferromagnetic core.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 shows the ignition coil 10 in accordance with the teachings of the present invention. The ignition coil 10 has a housing 12 that has an interior 14 adapted to receive a ferromagnetic core 16. Typically, a potting material 18 encapsulates the interior 14 of the ignition coil 10. Typically, the potting material will be any of a number of dielectric materials which provides a limited insulation and prevents external contamination which could lead to premature failure of the ignition coil 10.

(7) The ignition coil 10 has the ferromagnetic core 16 with a first side 20 and a second side 22. The ferromagnetic core 16 has a generally rectangular configuration. A primary coil 24 surrounds the first portion 20 of the ferromagnetic core 16. A secondary coil 26 surrounds the second portion 22 of the ferromagnetic core. In particular, it can be seen that there is a bobbin 28 that has an interior that is positioned over the opposite side 22 of the ferromagnetic core 16. In particular, the bobbin 28 has a plurality of bobbin flanges 30 that radiate outwardly from a central core 32. The secondary coil 26 is received in this plurality of bays defined by the bobbin flanges 30 and the central core 32. The secondary coil 26 is illustrated partially in FIG. 1. It is understood that the coils will be received in the plurality of bays of the bobbin 28. Importantly, there is a form 34 that will be interposed between the secondary coil 26 and the second portion 22 of the ferromagnetic core 16. This form 34 will be of a non-ferrous metal.

(8) FIG. 2 is an isolated view showing the second portion 22 of the ferromagnetic core 16 as received within the interior of the bobbin 28. It can be seen that the bobbin 28 includes a plurality of bobbin flanges 30 that define a plurality of bays 38. The bobbin flanges 38 are annular members that radiate outwardly from the core 32 of the bobbin 28. The secondary coil will be received in this plurality of bays 38 (as described hereinbefore).

(9) Importantly, in FIG. 2, the form 34 is particularly illustrated as being interposed between the secondary coil and the second portion 22 of the ferromagnetic core 16. The form 34 extends longitudinally along a length of the second portion 22 of the ferromagnetic core 16. As stated hereinbefore, it is important that this form be of a non-ferrous metal. The form 34 extend substantially along the entire length of the bobbin 28. In FIG. 2, it can be seen that the form 34 is affixed to an inner wall 42 of the bobbin 34. However, within the concept of the present invention, the form can be placed in other locations, as described hereinafter. The form 34 will have a generally tubular shape. Importantly, the tubular shape will have a split extending longitudinally therealong so as to interrupt the circularity of the tubular shape so as to not be connected in a closed loop with itself. This prevents current from flowing around the non-ferrous metal form 34.

(10) A frame 44 is illustrated as affixed to an exterior of the second portion 22 of the ferromagnetic core 16. The frame 44 will be of a non-metallic material. In an alternative embodiment, the frame 44 can simply be interposed between the second portion 22 of the ferromagnetic core 16 and the form 34.

(11) FIG. 3 shows the secondary side of the ignition coil 10 of the present invention. The ferromagnetic core 16 is illustrated as extending into the interior of the bobbin 28. The interior of the bobbin 28 is of a generally rectangular or square shape 50. It can be seen that the form 34 will extend substantially around the exterior of the second portion 22 of the ferromagnetic core 16. There is a gap 52 in the shape of the form 34. The frame 44 is illustrated in FIG. 3 as being interposed between the form 34 and the exterior of the second portion 22 of the ferromagnetic core 16. If desired, the frame 44 can simply be affixed to the ferromagnetic core 16. This frame 44 is of a non-metallic material.

(12) FIG. 4 shows the secondary side of the ignition coil 10 from an opposite end from that of FIG. 3. In FIG. 4, the bobbin 28 will have a circular or round interior 60. As such, the form 34 will have a generally circular or tubular shape which conforms to the circular wall 60 of the bobbin 28. The second portion 22 of the ferromagnetic core 16 is illustrated as located centrally within the interior of the form 34. A split 64 is formed in the circular shape of the form 34 so as to interrupt the circularity of the form 34. The non-metallic frame 44 is illustrated as positioned over the second portion 22 of the ferromagnetic core 16.

(13) FIG. 5 shows an alternative embodiment of the secondary side of ignition coil 10 from an opposite end of that of FIG. 3. In FIG. 5, the bobbin 28 will have a round or circular interior 60. As such, the metallic surround form 70 will have a generally circular or tubular shape which conforms to the circular wall 60 of the bobbin and 28. The second portion 72 of the ferromagnetic core 16 is illustrated as located centrally within the interior of the metallic surround form 70. A spaced gap 74 is shown in the metallic surround form 70. A metallic piece 76 is located in this split 74. The metallic piece 76 in the spaced gap 74 interrupts the circularity of the metallic surround form 70. Unlike the embodiment shown in FIG. 4, there is no non-metallic frame 44 positioned over the second portion 72 of the ferromagnetic core 16. The metallic surround form 70 is formed of a non-ferrous material. In this embodiment, the metallic piece 74 joins the metallic surround form 70 to the ferromagnetic core 72.

(14) As shown in the previous drawings, it has been found that the insulating material of the ignition coil 10 is more uniformly stressed between the ferromagnetic core 16 and the secondary winding 26. The non-ferrous metal form 34 is configured in a circular shape, or other shape, that surrounds a percentage of the ferromagnetic core and the inner barrel of the bobbin 28. This non-ferrous metal form 34 will extend in a longitudinal direction generally concentric with that of the second portion 22 of the ferromagnetic core 16. This form 34 can be isolated from or joined to the ferromagnetic core. This non-ferrous metal form 34 serves to diminish dense electrical fields and provide a more uniform flux density. The form 34 reduces the surface charge densities on the smaller radius areas of the ferromagnetic core. As such, the insulation material is more uniformly stressed. The form 34 is separated on one side so as to not be connected in a closed loop with itself As such, current cannot flow around the non-ferrous metal form 34. The present invention allows for increased potential voltages between the secondary side of the coil and the ferromagnetic core 16 that would normally result in an electrical breakdown between these assembly components. Sample testing has verified that this configuration can improve the coil's unloaded operating life expectancies to greater than ten times that of the same coil without the configuration.

(15) The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction can be made within the scope of the appended claims without departing from the true spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.