JPH0246790B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an ignition distributor for use in an internal combustion engine.

Conventional ignition distributors of this type include a cap carrying a center electrode and side electrodes, and a rotor rotatably disposed within the cap relative to the cap, the rotor having a synthetic It has a resin body and a conductive rotor arm integrally molded within the body, the rotor arm having an exposed central portion and a conductive rotor arm extending from the body in a direction substantially perpendicular to the rotor axis. and a protruding tip portion protruding outward, and when the rotor rotates, the exposed central portion of the rotor arm is brought into sliding contact with the center electrode, and the protruding end portion rotates opposite the side electrode. It is configured so that it can be used.

When molding the rotor of the above-mentioned conventional ignition distributor, the protruding tip of the rotor arm is supported by the mold from above and below, and the exposed center is supported by the mold from above, and the exposed center is brought into contact with the mold. I was starting to push myself. However, since a force is applied to the protruding tip of the rotor arm to bring the exposed central part of the rotor arm into contact with the mold, it is difficult to bring the entire exposed central part into close contact with the mold. Therefore, a gap is formed between the exposed center portion and the mold, and the forming material flows into the gap to form a thin film of molding material on the surface of the exposed center portion. There is a problem in that the formation of this thin film impairs the electrical conductivity between the center electrode and the exposed central portion of the rotor arm.

An object of the present invention is to form a thin film of molding material on the surface of the exposed central part of the rotor arm when molding the rotor, and to prevent electrical conduction between the exposed central part and the center electrode when the exposed central part and the center electrode come into sliding contact. An object of the present invention is to provide a method for manufacturing an ignition distributor for an internal combustion engine equipped with a rotor arm that does not cause any damage.

In order to achieve such an object, the present invention forms an extension part projecting from the exposed central part in the opposite direction of the protruding tip part of the rotor arm, exposes at least a part of the extension part, and molds the rotor. In doing so, the rotor arm is supported by a mold with its protruding tip from both sides in the vertical direction, its exposed central part from one side, and the exposed part of its extension from the other side. A manufacturing method is adopted in which the mold and the exposed central portion are brought into close contact with each other.

According to the manufacturing method described above, the rotor arm is not supported in a cantilever manner, but is held and positioned in both directions (up and down) by the mold at three points: the protruding tip, the exposed center, and the exposed part of the extension. It will be supported. This ensures that the exposed central portion is in intimate contact with the mold. Therefore, it is completely prevented that a gap is formed between the exposed center portion and the mold die, and that molding material flows into the gap to form an insulating film.

In the conventional manufacturing method, the rotor arm is positioned and molded so as not to move within a horizontal plane. However, as in the method of the present invention, it has not been considered to position the rotor arm at three points to prevent movement in the vertical direction so as to provide so-called double-sided support.
During molding, a gap is created between the exposed central portion of the rotor arm and the mold, and molding material flows into the gap. As a result, a thin film of the molding material was formed on the exposed central portion, deteriorating the conductivity between the center electrode and the exposed central portion of the rotor arm. Therefore,
This inevitably required additional processing to remove the thin film. According to the manufacturing method of the present invention, the exposed central part of the rotor arm and the mold are kept tightly together, the molding material is prevented from flowing in, and there is a good gap between the center electrode and the exposed central part of the rotor arm. Ensures a good electrical contact.

Hereinafter, a product manufactured by the manufacturing method of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, an ignition distributor 10 for an internal combustion engine according to an embodiment of the present invention.
The cap 12 is made of synthetic resin, and the cap 12 has a cylindrical wall 14 and an end wall 16 that closes one end of the cylindrical wall in the axial direction. An end of a shaft 18 projects into the cap 12 in a concentric relationship with the cylindrical wall 14 of the cap, and a rotor 20 is fixed to the end of the shaft 18 and rotates along with the shaft 18. It is adapted to be rotated within the cap 12.

As shown in FIGS. 1-3, the rotor 20 has a main body 22 made of synthetic resin and a rotor arm 24 made of metal, such as brass, integrally molded with the main body 22. As shown in FIGS. The main body 22 is
A cylindrical center part 26 fixed to the end of the shaft 18 by a set screw or other suitable means, and a protrusion part 30 projecting radially outward from the center part 26 and integrally formed with the center part. , projecting radially outwardly in a direction diametrically opposite to the protrusion, the central portion 26
and a counterweight portion 28 integrally formed with the counterweight portion 28 .

The rotor arm 24, which is made of a metal material with a higher specific gravity than the resin forming the main body 20, has an exposed central portion 32 and a direction perpendicular to the axis of rotation of the rotor 20, that is, radially outwardly. An arcuate protruding tip portion 3 protruding from the protruding portion 30 of the main body 20
4, and an extension 36 projecting radially outward from the exposed central portion 32 in a direction diametrically opposite to the projecting tip. The portion of the rotor arm 24 between the protruding tip 34 and the exposed central portion 32 is cast into the protruding portion 30 of the main body 20, and the portion of the extension 36 adjacent to the exposed central portion 32 is a counterweight portion. It is cast into 28.

The counterweight portion 28 is provided with a cavity, specifically a hole 38 having a rectangular cross section, which extends in a plane perpendicular to the rotational axis of the rotor 20 and in a direction perpendicular to the longitudinal direction of the rotor arm 24. and the extension 36 of the rotor arm 24 is inserted into the hole 3.
8, so that a portion of its extension 36 is exposed. Also,
Since such a hole 38 is provided in the counterweight portion 28, thin-walled portions 40 and 42 are formed in the counterweight portion 28 above and below the hole 38 in FIG. 1, respectively.

A number of side electrodes 48 corresponding to the number of cylinders of the engine are cast into the outer periphery of the end wall 16 of the cap 12, and these side electrodes 48 are spaced apart from each other at equal intervals in the circumferential direction. At the same time, it is positioned opposite to the circular trajectory drawn by the protruding tip end of the rotor arm 24 when the rotor 20 rotates. Also, the end wall 16 of the cap 12
A center electrode 50 is cast in the center of the center electrode 50, and a carbon brush 52 is accommodated in a hole provided at one end surface of the center electrode 50. and,
The carbon brush 52 is biased in a direction protruding from the hole by a spring 54 housed in the hole, and is brought into sliding contact with the exposed central portion 32 of the rotor arm 25. Center electrode 50
is electrically connected to an ignition coil (not shown) via a high tension cord (not shown), and the side electrode 48 is electrically connected to a spark plug via a high tension cord (not shown).

When the shaft 18 rotates in synchronization with the rotation of the engine, the rotor 20 rotates, and the tip 34 of the rotor arm 24 is successively opposed to the side electrodes 48. The voltage is distributed to the side electrodes 48. In this way, when the rotor 20 is rotated, the counterweight portion 2 of the rotor 20
8 is the protrusion 30 of the main body 22 and the rotor arm 2
The weight of the radial protrusion 4 is balanced to prevent rotational wobbling of the shaft 18 and rotor 20.

The counterweight portion 28 of the rotor 20 used in the ignition distributor 10 manufactured according to the present invention is provided with a hole 38, and the extension portion 36 of the rotor arm 24 is inserted into the hole 38. Since a part of the extension part 36 is exposed, when the rotor 20 having the synthetic resin main body 22 and the metal rotor arm 24 is integrally molded, the rotor arm can be removed as shown in FIG. The protruding tip portion 34 of No. 24 is viewed from above and below as indicated by B ₁ and B ₂ , that is, from both sides, the exposed central portion 32 is viewed from above as indicated by A, and a portion of the extension portion 36 located within the hole 38 is viewed from above as indicated by C. In other words, the rotor 20 is supported by a mold from the bottom direction shown in FIG.
When molding the rotor arm 24 at the above three points,
Furthermore, since the exposed central portion and the extension portion are supported on opposite sides, the mold is pressed firmly against the exposed central portion 32 and brought into close contact with the exposed central portion 32, thereby creating a gap between the mold and the exposed central portion 32. is formed, the molding material flows into the gap, and the rotor arm 2 is prevented from forming a thin film on the surface of the exposed central portion 32.
Good electrical continuity can be obtained between the exposed central portion 32 of No. 4 and the carbon brush 52.

Further, since the extension portion 36 of the metal rotor arm 24 is inserted into the counterweight portion 28 and acts as a part of the counterweight, the volume of the resin counterweight portion 28 itself can be reduced. The amount of shrinkage in the resin counterweight portion 28 during molding is reduced, and the dimensional accuracy of the rotor 20 consisting of the resin main body 22 and the metal rotor arm 24 can be maintained at a high level.

Further, since the resin counterweight portion 28 is provided with thin portions 40 and 42 formed by the hole 36 in a portion adjacent to the cylindrical center portion 26, the thin portions 40 and 42 formed by the counterweight portion 28 are Shrinkage during molding occurs in the thin parts 40, 42.
The cylindrical center portion 26 is absorbed by the cylindrical center portion 26 and its contraction does not affect the cylindrical center portion 26. This also increases the dimensional accuracy of the rotor 20 made of the resin main body 22 and the metal rotor arm 24.

Although the holes 38 in the counterweight portion 28 shown in FIGS. 1-3 have a rectangular cross-section, they may also have a circular cross-section, and as shown in FIG. One side wall surface of the hole 38 may have an arc shape instead of a straight line shape. Additionally, although the extension 36 of the rotor arm 24 is shown in FIGS. 1-4 as extending across the width of the bore 38, the extension 36 extends only partially into the bore 38. The extension portion 36 may be made to protrude from the outside, as long as the extension portion 36 can be supported from the direction C in FIG. 3 by the mold during molding. In any case, this hole 38 is formed as a cutout of the mold part that supported the extension part 36, and is located within a plane perpendicular to the rotational axis of the rotor 20 and within the rotor arm 2.
rotor arm 2 because it extends across rotor arm 2
When the protruding tip 34 of No. 4 faces the regular side electrode 48, the hole 38 does not face the side electrode 48 on the opposite side. Therefore, there is no possibility that power is incorrectly distributed from the extension portion 36 to the opposite side electrode via the hole 38.

FIG. 5 shows another example of an ignition distributor 100 for an internal combustion engine manufactured by the manufacturing method of the present invention, and this ignition distributor 100 has a cap 112 made of synthetic resin such as plastic.
The cap 112 has a cylindrical wall 11
4 and an end wall 11 that closes one end of the cylindrical wall in the axial direction.
6. End wall 116 of cap 112
A number of side electrodes 148, 149 corresponding to the number of cylinders of the engine are cast into the outer periphery of the engine.
In addition, a first center electrode 15 is provided at the center of the end wall 116.
0 also has a second center electrode 151 cast therein radially outwardly from the first center electrode.

Inside the cap 112 is the cylindrical wall 1 of the cap.
The end of a shaft 118 is protruded in a concentric relationship with the rotor 14.
20 is fixed with a set screw 121 and the shaft 118
It is adapted to be rotated within the cap 112 together with the cap. The rotor 120 has a main body 122 made of synthetic resin and first and second rotor arms 124 and 125 made of metal such as brass, which are integrally molded into the main body 122. rotor arms 124 and 12 of
5 are spaced apart from each other in the axial direction of the main body 122. The main body 122 includes a lower cylindrical center portion 126 fixed to the end of the shaft 118 by suitable means such as a set screw 121, and an upper cylindrical center portion 127.
, a protrusion 130 projecting radially outward from the top of the lower central portion 126, and a lower central portion 1
A counterweight part 1 protrudes radially from the top of 26 in a direction diametrically opposite to the protruding part 130.
28, and a cup-shaped portion 131 integrally formed at the top of the upper central portion 127. and,
The connection between the counterweight portion 128 and the lower central portion 126 is provided with an opening or hole 138 similar to the example shown in FIGS. is provided.

The first rotor arm 124 has a substantially recessed exposed central portion 132, an arcuate projecting tip 134, and an extension 136, substantially similar to that shown in FIGS. 1-3. The same, but with a bent portion 135 between the exposed central portion 132 and the tip portion 134.
They differ only in that they are equipped with The second rotor arm 125 has a ring-shaped portion 137 placed on the bottom wall of the cup-shaped portion 131 and an arc-shaped projecting tip portion 139 that projects from the ring-shaped portion and from the peripheral wall of the cup-shaped portion 131. are doing. The carbon brush 152, which is slidably housed in the hole of the first center electrode 150, is moved by a spring to the first center electrode 150.
The carbon brush 153 is in elastic contact with the exposed central portion 132 of the rotor arm 124 and is slidably accommodated in the hole of the second center electrode 151.
The ring-shaped portion 137 of the second rotor arm 125 is brought into elastic contact with the ring-shaped portion 137 by a spring.

When the ignition distributor shown in FIG. 5 is activated, the shaft 11
8 rotates, and as a result, the first rotor arm 1
The 24 protruding tips 134 are successively opposed to the side electrodes 149, and distribute the high voltage supplied from the first center electrode 150 via the carbon brush 152 to the side electrodes 149. Also, the second
The protruding tip portion 139 of the rotor arm 125 is successively opposed to the side electrodes 148, and distributes the high voltage supplied from the second center electrode via the carbon brush 153 to the side electrodes 148.
In the distributor shown in FIG. 5, when the protruding end 134 of the first rotor arm 124 is opposed to the side electrode 149, at the same time the protruding end 139 of the second rotor arm 125 is placed opposite the side electrode 149. This is a distributor for a so-called two-ignition engine, which is arranged to face an electrode 148.

The configuration of the ignition distributor shown in FIG. 5, which includes the first center electrode 150, the first rotor arm 124, the counterweight portion 148, the hole 138, and the cylindrical center portion 126, is similar to that shown in FIGS. Although it is substantially the same as that shown in FIG. A greater effect can be expected on the ignition distributor shown in the figure in terms of preventing deformation during positioning molding.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a part of an ignition distributor for an internal combustion engine manufactured by the manufacturing method of the present invention, FIG. 2 is a plan view of the rotor shown in FIG. 1, and FIG. 4 is a diagram similar to FIG. 2, showing a modified example of the rotor,
and FIG. 5 is a sectional view of another example of an ignition distributor manufactured by the manufacturing method of the present invention applied to a two-point ignition type distributor. 10...Ignition distributor for internal combustion engine, 12...Cap, 14...Cylindrical wall, 16...
...End wall, 18...Shaft, 20...Rotor, 22...
Main body, 24...Rotor arm, 26...Cylindrical center part, 28...Counterweight part, 30...Protrusion part, 32...Exposed center part, 34...Protrusion tip part,
36... extension, 38... void, i.e., hole, 40,
42... Thin wall part, 48... Side electrode, 50...
Center electrode, 52...Carbon brush, 54...Spring, 100...Ignition distributor, 112
... Cap, 114 ... Cylindrical wall, 116 ... End wall, 118 ... Shaft, 120 ... Rotor, 121 ...
...Set screw, 122...Body, 124, 125...
...Rotor arm, 126...Lower cylinder center part, 1
27... Upper cylindrical center part, 128... Counterweight part, 130... Projection part, 131... Cup-shaped part, 132... Exposed center part, 134... Projection tip part, 135... Bent part, 136 ...extension part,
137...ring-shaped part, 138...hole, 139...
...Protruding tip, 148, 149...Side electrode,
150, 151... center electrode, 152, 153...
...Carbon brush.

Claims (1)

[Claims] 1. A cap that supports a center electrode and side electrodes, and a rotor rotatably disposed within the cap so as to be rotatable relative to the cap, the rotor having a main body made of synthetic resin and , having an electrically conductive rotor arm integrally molded within the body, the rotor arm having an exposed central portion and extending outwardly from the body in a direction substantially perpendicular to the axis of rotation of the rotor. It is equipped with a protruding tip that protrudes toward the
An ignition distributor for an internal combustion engine, wherein when the rotor rotates, the exposed central portion of the rotor arm is brought into sliding contact with the center electrode, and the protruding tip portion is rotated to face the side electrode. In forming the rotor by supporting the rotor arm in a mold and molding it with a synthetic resin constituting the synthetic resin body, the rotor arm is held at its protruding tip from both sides in the vertical direction. The exposed central portion is supported by a mold from one side, and the extension portion protruding in the opposite direction of the projecting tip with respect to the exposed central portion from the other side. and after molding, the part of the mold that supported the extension has a cavity extending in a plane perpendicular to the axis of rotation of the rotor and across the rotor arm. A method of manufacturing an ignition distributor for an internal combustion engine, characterized in that the ignition distributor is formed in the synthetic resin main body.