JPS6237321Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetic switch for a starter of a vehicle engine.

This type of magnetic switch includes a synthetic resin bobbin around which an excitation coil is wound, and a plunger with a movable contact attached to one end is slidably installed inside the bobbin. At the time of starting, the plunger is slid by energization of the coil, and its movable contact is brought into contact with a fixed contact disposed opposite to it, thereby forming an energization circuit for the starter motor. However, in the conventional structure, the coil is wound in contact with the outer periphery of a cylindrical bobbin, and the bobbin is significantly affected by the heat of the coil. The starter's magnetic switch coil, which is set to a time rating, generates heat and rises in temperature when energized.
As the heat was transferred to the bobbin, the bobbin was thermally deformed and softened, and its inner diameter side was affected. Therefore, in order to ensure sliding movement of the plunger even in such cases, a metal cylindrical bushing was fitted, and a structure was adopted in which the bushing supported the soft iron plunger. In order to maintain a slidable dimensional relationship, the gap between them is large, which has the disadvantage of causing fretting wear between the metals due to excessive vibration.

The present invention solves the above-mentioned problems of the prior art. Therefore, the purpose of the present invention is to prevent the bobbin from being thermally influenced by the excitation coil located on the outer circumference of the bobbin, and to To provide a magnetic switch which can ensure sliding movement of a plunger without having a bush.

In order to achieve the above object, the magnetic switch according to the present invention is characterized in that the bobbin consists of a cylindrical boss part and a tooth part located on the outer periphery of the boss part and extending in the axial direction. The tooth length and number of teeth are sufficient to avoid contact with the boss.

Next, the drawings will be explained. Figure 1 shows a conventional magnetic switch.
is a solenoid part, 2 is a bobbin made of synthetic resin, preferably thermoplastic resin, and 3 is a bobbin 2.
4 is a metal bush, and 5 is a plunger slidably provided in the bobbin 2 via the bush 4. At one end of the plunger 5 is a joint 6 which, although not shown, is connected to a pinion transition member such that movement of the plunger 5 causes the pinion to engage a ring gear of the engine. When the current to the coil is cut off, the plunger 5 is returned to its original position by a return spring. Furthermore, a movable contact 7 is provided at the other end of the plunger 5.
is attached, and fixed contacts 8 and 9 arranged opposite thereto are fixed to the cover 10. cover 1
0 is connected to a housing 11 in which the solenoid part 1 is housed. In the conventional structure as shown in FIG. 1, the coil 3 comes into contact with the outer periphery of the bobbin 2, resulting in the above-mentioned drawbacks.

As shown in FIGS. 2 and 3, the magnetic switch according to the present invention is characterized by the structure of a bobbin 2 around which an excitation coil 3 is wound.
includes a cylindrical boss part 21 and a gear-shaped tooth part 22 that is located on the outer periphery of the boss part and extends in the axial direction. It is set to a value that makes contact with the boss portion 21 but does not make contact with the boss portion 21. Therefore, by making the outer circumferential surface of the bobbin 2 tooth-shaped, there is a gap between the bobbin's contact portion with the coil 3 and the bobbin's boss portion 21 that provides the guide surface 23 of the plunger 5. Moreover, a space is interposed between the coil 3 and the coil 3. In the figure, 2
Reference numeral 4 denotes disc-shaped collars provided at both ends of the bobbin 2, and the coil 3 is installed between them.

During operation, when the coil 3 is energized, the plunger 5 moves to the right in Fig. 1 due to its magnetic force.
The movable contact 7 contacts the fixed contacts 8 and 9, and supplies power to a starter motor (not shown). In this case, when the starter is used for a long time, heat is generated in the coil 3. However, since the boss portion 21 of the bobbin is separated from the coil 3 and there is a space between them, the heat generated in the coil 3 is transferred to the bobbin 2. This is also related to the fact that it is made of a resin with a low resin content, so that almost no energy is transmitted to the boss portion 21 . Further, the thermal deformation is limited to only the tips of the teeth 22 that are in contact with the coil 3, and this deformation does not affect the boss portion 21. Note that loosening of the coil 3 due to deformation of the tips of the teeth on the bobbin can be prevented by selecting the material to be deformed and bonded.

Therefore, according to the present invention, since the coil does not touch the boss part of the bobbin, the sliding surface of the plunger inside the bobbin is not thermally affected by the coil, so the plunger can be directly connected to the resin bobbin. The bushing on the inner circumferential surface of the bobbin, which is conventionally required, is no longer necessary. Therefore, the magnetic switch of the present invention has excellent vibration resistance and has a small number of parts.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of a conventional magnetic switch, Fig. 2 is a partial perspective view showing an example of a bobbin used in the magnetic switch of the present invention, and Fig. 3 is a main part of the magnetic switch of the present invention. FIG. In the figure, 2... bobbin, 3... coil, 21...
Boss portion of the bobbin, 22...teeth portion of the bobbin.

Claims (1)

[Scope of utility model registration request] In a starter magnetic switch including a synthetic resin bobbin around which an excitation coil is wound, the bobbin is comprised of a cylindrical boss portion and teeth extending in the axial direction on the outer periphery of the boss portion, A magnetic switch characterized in that the tooth portion has a tooth height and a number of teeth such that the coil contacts the tooth tip portion but does not contact the boss portion.