It is common practice for coil-on-plug ignition systems for automotive internal combustion engines to provide a core assembly 10 as shown in prior art
As shown in
Specifying the grain direction 14 of the electrical steel is important because magnetic flux density is increased in the rolling direction. Higher flux density at low power levels provides for a quick spark response and discharge within the ignition coil without higher losses. The T core 12 can always be produced with the grain direction running parallel to the length of the part. However, the O cores 11 will have the sides 15C and 15D as shown in
It is an object to improve upon the prior art ignition coil and manufacturing method described above.
In an automotive plug ignition coil core system and method, a first core is formed of stacked laminations each of which comprises a segmented lamination strip folded around to create an enclosed loop shape. Each strip has four segments and a hinge web is provided between first and second, second and third, and third and fourth segments. A grain direction of electrical steel runs lengthwise in each of the segments. A second core inside of the closed loop first core is formed of a plurality of stacked laminations, each lamination having a grain direction of electrical steel running lengthwise.
For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the preferred exemplary embodiment/best mode illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, and such alterations and further modifications in the illustrated embodiment and such further applications of the principles of the invention as illustrated as would normally occur to one skilled in the art to which the invention relates are included.
The improved ignition coil and method for making the same is shown in
A top view of the improved core 16 is shown in
Also as shown in
When the segments are wrapped around at the respective hinge webs 21, 22, and 23 and the interlock projections 38 and receptacles 39 are engaged with one another, edge abutment lines 28, 29, 30, and 31 are formed. Thus, after folding at the hinge webs, the final shape of O core 16 results as illustrated in
The manufacture of the individual segmented lamination strips for laminations in 16A is shown in the top view of
As can be seen in
In
The improved core assembly of a preferred embodiment thus has several advantages over the previously described prior art core assembly:
1. a grain direction of the electrical steel material always runs parallel with the individual sides of the O core;
2. in multi-row die configurations, the improved method of the preferred embodiment uses less material than the current prior art method—the example O core running in four row tooling uses 14 percent less material than the prior art method; and
3. separate processes are used to produce the O core parts and the T core parts, allowing for different materials to be chosen for the respective O and T cores without excessive material usage penalties.
With the preferred embodiment method, the segmented lamination strips are punched as the electrical steel strip material travels progressively through the stamping die adding additional features at each station. The finished segment strip cores exit the stamping die and are then ready for final forming. The segmented strip core is then formed into the finished rectangular shape manually or by automated machine.
The O core may have other shapes than that described and the T core may also have other shapes than that described in the preferred embodiment. Also the interlock members at the end of the first segment and the fourth segment which mate with each other may have various shapes.
The interlock protrusions for locking laminations together may have a variety of different shapes and arrangements.
The hinge web connecting adjacent segments can vary in design and shape. The layout of the segmented lamination strips on the material strip being punched can be varied, as can the layout for the T core laminations in their respective material strip.
Although a preferred exemplary embodiment is shown and described in detail in the drawings and in the preceding specification, it should be viewed as purely exemplary and not as limiting the invention. It is noted that only a preferred exemplary embodiment is shown and described, and all variations and modifications that presently or in the future lie within the protective scope of the invention should be protected.
The present application is a divisional of U.S. Ser. No. 13/447,433 titled “IMPROVED IGNITION COIL AND MANUFACTURING METHOD” filed Apr. 16, 2012.
Number | Date | Country | |
---|---|---|---|
Parent | 13447433 | Apr 2012 | US |
Child | 14835921 | US |