System and method for winding an ignition coil

Abstract

A coil winding system is provided for making a secondary winding for an automotive ignition coil. The system includes a roller configured to apply a holding force to wire being dispensed from a wire nozzle onto a bobbin. The nozzle and roller are moved by a drive mechanism under control of a controller from one axial end to the other axial end of the bobbin for winding the bobbin in a progressive winding fashion. The roller allows an increase in the winding angle of the layers, which reduces the voltage difference between adjacent layers, thereby reducing incidence of dielectric break down in that region.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention relates generally to the field of engine ignition coils, and, more particularly, to a system and method for winding an ignition coil.

[0003] 2. Description of the Related Art

[0004] It is known to use an automated winding system for the manufacture of ignition coils wherein the system has a plurality of spindles for receiving empty coil spools or bobbins, as seen by reference to U.S. Pat. No. 5,950,956 issued to Yukitake. Yukitake discloses an ignition coil winding machine capable of simultaneously forming a plurality of engine ignition coils. The machine has a driver for rotating a shaft on which a coil bobbin is disposed, all under the control of a controller. The machine further includes a tensioning device in between a wire spool (containing wire destined for being wound on the bobbins) and a nozzle. The nozzle reciprocates in the coil winding direction, thereby laying out the wire on the bobbin according to a method specified in the Yukitake patent.

[0005] It is also known to provide an ignition coil of the type suitable for mounting directly above the spark plug, sometimes referred to as a “pencil” coil, that employs a progressive wound secondary winding, as set forth in U.S. Pat. No. 6,276,348 issued to Skinner et al. entitled “IGNITION COIL ASSEMBLY WITH SPOOL HAVING RAMPS AT BOTH ENDS THEREOF.” As disclosed in Skinner et al., a progressive winding is a one segment winding where a “top” layer advances under an angle from one end of the spool to the other. The winding angle is important in such a configuration because it sets the voltage difference between adjacent layers. In current, conventional pencil coils, a typical winding angle ranges between about 8-12 degrees. Increasing the winding angle, however, has been heretofore limited by the wire collapsing at the bottom of the winding. Increasing the winding angle would be beneficial inasmuch as it would be reduce the voltage difference between adjacent wire layers, thereby decreasing the risk of failure due to voids produced in the secondary winding area. That is, in a conventional pencil coil, the secondary winding region is encapsulated with a dielectric material, such as an epoxy potting material. Increased voltage differences may break down such dielectric material, thereby allowing a short circuit between turns.

[0006] There is therefore a need for an improved winding system that minimizes or eliminates one or more of the problems as set forth above.

SUMMARY OF THE INVENTION

[0007] One advantage of the present invention is that it solves one or more of the problems set forth above. Another advantage of the present invention is that it facilitates manufacture of a progressive wound coil having an increased winding angle, which reduces a voltage difference between adjacent layers, thereby reducing the occurrence of dielectric break down and possible coil failure. In addition, the invention provides an improved robustness of the winding due to a reduction or elimination of the occurrence of wire movement during the winding process.

[0008] In accordance with the present invention, a method is provided for winding a bobbin having a main axis to form a coil. The method comprises the step of holding the wire being wound on the bobbin in place using a roller. Accordingly, increased winding angles can be employed inasmuch as the wire layers need not rely solely on the tension in the wire during winding to maintain placement, but also benefits from the force exerted by the roller to keep the wire in place.

[0009] In a preferred embodiment, the roller comprises an outer surface formed of a material having a predetermined hardness (or pliability, as the case may be), for example, rubber having a preselected durometer. In a still further preferred embodiment, the outer surface of the roller is formed so as to have a predetermined pattern configured to facilitate holding the wire in place.

[0010] In another aspect of the invention, a system for winding a bobbin is also presented.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Additional objects and advantages of the present invention will be more readily apparent from the following detailed description of preferred embodiments thereof, when taken together with the accompanying drawings in which:

[0012] FIG. 1 is a simplified block diagram view of a winding system according to the present invention;

[0013] FIG. 2 is a partial, perspective view showing the winding system of FIG. 1 in a multi-spindle configuration;

[0014] FIG. 3 is a simplified cross-sectional view of a bobbin being wound using a progressive winding strategy; and

[0015] FIG. 4 is a simplified cross-sectional view of the bobbin of FIG. 3 enlarged, showing use of a roller according to the invention.

[0016] FIG. 5 is a simplified side view of an alternate preferred embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views, FIG. 1 shows a winding system 10 in accordance with the present invention. Winding system 10 includes a main controller 12, a dereeler assembly 14, and a base with a drive portion 16 that includes one or more spindles 18 and corresponding number of nozzles 20. The basic winding system 10 (exclusive of a roller 40 to be described below) is generally of a conventional nature and may be any one of a number of commercially available systems. For example, a multi-spindle coil winding machine (exclusive of roller 40 and the accompanying software functionality to be described in detail hereinafter), may be obtained from Prosys Industries, Inc., Plymouth, Mich., USA or Marsilli, for example only. FIG. 1 further illustrates an ignition coil bobbin 22, a wire feed assembly 24 comprising wire 26 contained on spool 28. In alternate embodiments, the winding system 10 may comprise a single-spindle winder, a fly type winder (i.e., post for receiving bobbin does not move but winding head does), an insertion type winder, an armature type winder, and a yolk type winder.

[0018] FIG. 2 illustrates the drive portion 16 of machine winding system 10 in greater detail. As shown in FIG. 2, winding system 10 is of the type that is capable of simultaneously winding at least one, and for example, a plurality of bobbins 221, 222, . . . , 22i respectively mounted to spindles 181, 182, . . . , 18i. Corresponding parallel structure such as nozzles 201, 202, . . . , 20i, and dereeler assemblies 141, 142, . . . , 14i are operative to feed respective runs of wire 261, 262, . . . 26i for winding ignition coils. As also shown, corresponding parallel structure also includes a plurality of rollers 401, 402, . . . 40i to facilitate holding the wire in place as it is being dispensed and wound onto the bobbins.

[0019] With continued reference to FIG. 1, generally, wire 26 is drawn from spool 28 and is fed through dereeler 14, which may provide a tensioning and/or take-up function relative to the wire 26. Drive portion 16 is configured, generally, to rotate spindle 18 containing bobbin 22, and, further, to reciprocate nozzle 20 over a preprogrammed axial length over bobbin 22. Drive portion 16 operates in accordance with control signals received from and generated by controller 12. Nozzle 20 can be moved by drive portion 16 axially with respect to spindle 18, as well as being rotated, all as known to one of ordinary skill in the art. Roller 40, generally, is moved in a manner corresponding to the movement of nozzle 20, preferably, in synchronism therewith. Roller 40 is operative to hold the wire in place as it is being dispensed onto the bobbin 22.

[0020] Through the foregoing, a variety of coils having desired winding patterns may be made. In a preferred embodiment, the coil may be a primary or secondary coil of an ignition coil for an engine, such as an automotive engine. It should be understood that the invention may be used for many other types of winding patterns and coil types.

[0021] FIG. 3 is a simplified cross-sectional view showing the winding process for one bobbin 22 in greater detail. In one embodiment, bobbin 22 comprises a secondary winding bobbin for use in an ignition coil (i.e., a “pencil” coil) for an internal combustion engine. The bobbin 22 is substantially cylindrical and extends along a main axis 34, and has opposing first and second axial ends 30 and 32. A winding bay is defined between tapered surfaces of winding flanges located at axial ends 30, and 32. As further illustrated in FIG. 3, in accordance with one embodiment of the present invention, a progressive winding approach is taken wherein wire 26 is set down in layers that move from one axial end (e.g., end 30) to the other axial end (e.g., end 32). As further shown, to achieve the progressive wound secondary winding, nozzle 20 moves axially, as described above. As shown in FIG. 3, nozzle 20 is shown in a first intermediate axial position 36, and a second intermediate axial position 38 between its beginning axial position and ending axial position near ends 30, 32, respectively. It should be understood, however, that the tapered ends are not needed for the present invention.

[0022] FIG. 4 is an enlarged view of a portion of FIG. 3 showing, in greater detail, the winding process according to the present invention. Bobbin 22 at axial end 30 includes a winding flange 39 that is tapered at a predetermined angle, designated &thgr; relative to a horizontal axis 41. Horizontal axis 41 is substantially parallel to main axis 34 of bobbin 22. In one embodiment, angle &thgr; is equal to or greater than about 13°, and less than or equal to about 90°.

[0023] Roller 40 is oriented, by way of connection to drive 16, so that its axis of rotation 42 is substantially parallel to the tapered winding surface of flange 39. Roller 40 is configured to apply a pressure, designated by vector 43 is FIG. 4, so as to hold wire 26 in place on spool 22 while nozzle 22 dispenses the same. Controller 12 is configured to move roller 40 in nozzle 20, relative to bobbin 22, from one axial end (e.g., end 30) to the other axial end (e.g., end 32) in a predetermined relationship, preferably, in synchronism.

[0024] For example, as shown in FIG. 4, roller 40 is moved from a first axial position 44 to a second, intermediate axial position 46. The roller would be moved by drive 16 under control of controller 12 all the way to end 32 of bobbin 22. It would then be programmed to move radially outwardly as the last layers of the winding are dispensed onto bobbin 22.

[0025] Roller 40, as mentioned above, is configured to rotate about its own axis of rotation 42. In the embodiment of FIG. 4, the roller 40 is generally cylindrical in shape, with tapered ends. However, other shapes may be used. In addition, roller 40 is provided with an outer surface formed of a material having a predetermined hardness. In one embodiment, roller 40 has an outer surface comprising a rubber material having a pliability within a preselected range. In alternate embodiments, roller 40 would be formed so that an outer surface thereof has a predetermined texture configured to facilitate holding wire 26 in place during winding.

[0026] FIG. 5 shows an alternate preferred embodiment of system 10, designated 10a in the drawing. In this alternate embodiment, an alternate shaped roller, designated roller 40a, is provided. Spool 40a is generally frusto-conical in shape, with an outer surface that tapers radially inwardly, as taken axially along axis 42a toward spool 22. Winder guide needle 20 and roller 40a move in direction 48 along the length of spool 22, just as described above for the first embodiment. In still other embodiments, multiple rollers may be employed around the circumference of bobbin 22.

[0027] It should be understood that the nozzle 20, while not shown in FIG. 4, will typically be disposed normal to the paper (either above the paper, or into or behind the paper) and roller 40.

Claims

1. A method of winding a bobbin having a main axis to form a coil comprising the step of holding wire being wound on the bobbin in place using a roller.

2. The method of claim 1 wherein said bobbin extends along the main axis and has first and second opposing axial ends, said bobbin having a winding flange at said first axial end tapered at a predetermined angle relative to said main axis, said method further including the step of orienting said roller such that a rotation axis associated therewith is parallel to said tapered winding flange.

3. The method of claim 2 wherein said wire is dispensed from a movable nozzle associated with a winding system, said method further comprising the step of:

moving said nozzle and said roller relative to said bobbin from said first axial end to said second axial end.

4. The method of claim 3 further comprising the step of:

providing said roller having an outer surface with a predetermined hardness.

5. The method of claim 4 wherein said providing step comprises the substep of:

selecting a material for said outer surface having a pliability within a preselected range.

6. The method of claim 4 wherein said providing step comprises the substep of:

selecting a rubber material for said outer surface.

7. The method of claim 3 wherein said providing step comprises the substep of:

forming said outer surface so as to have a predetermined texture configured to facilitate holding said wire in place.

8. The method of claim 1 wherein said wire is progressively wound according to a winding angle relative to said main axis, said method further comprising the step of:

orienting said roller so that a rotation axis associated therewith is parallel to said winding angle.

9. The method of claim 1 wherein said holding step comprises the substep of:

holding said wire using a plurality of rollers.

10. A method of winding a bobbin to form a secondary ignition coil comprising the steps of:

(A) providing a roller with an outer surface comprising rubber material having a hardness in a predetermined range;

(B) providing a nozzle configured to dispense wire onto said bobbin according to a progressive winding strategy with a winding angle relative to a main axis associated with said bobbin; and

(C) dispensing wire from said nozzle onto said bobbin and holding said wire in place using said roller.

11. The method of claim 10 further comprising the step of:

orienting said roller such that an axis of rotation associated therewith is parallel to said winding angle.

12. The method of claim 10 wherein said bobbin has first and second axial ends, and wherein said dispensing and holding step comprises the substep of:

moving said nozzle and roller relative to said bobbin from said first axial end to said second axial end.

13. A winding system for winding a bobbin to form a coil comprising:

a base including at least one spindle configured to receive said bobbin;

a nozzle proximate said spindle configured to dispense wire onto said bobbin;

a roller proximate said spindle configured to hold dispensed wire in place on said bobbin; and

a controller configured to rotate said spindle and move said nozzle and roller axially relative to said spindle.

14. The system of claim 13 wherein said roller is configured to allow rotation about a rotation axis associated therewith.

15. The system of claim 14 wherein said roller includes an outer surface comprising material with a hardness in a predetermined range.

16. The system of claim 15 wherein said material comprises rubber.

17. The system of claim 14 wherein said roller is oriented such that said rotation axis is parallel to a winding angle of the wire being dispensed by said nozzle.

18. The system of claim 14 wherein said system comprises a plurality of rollers associated with said at least one spindle.