JP4297036B2 - Electromagnetic switch - Google Patents

Description

  The present invention relates to an electromagnetic switch for a starter.

Conventionally, there is an electromagnetic switch that opens and closes a motor contact provided in a motor circuit of a starter. For example, an electromagnetic switch described in Patent Document 1 includes a set of fixed contacts connected to a motor circuit and a movable contact supported by an end of a plunger shaft via an insulator. The motor contact is closed by contacting the set of fixed contacts and conducting between the two fixed contacts, and the movable contact is separated from the set of fixed contacts and the conduction between the two fixed contacts is interrupted. The motor contact is opened.
JP-A-3-969

  However, in the electromagnetic switch described in Patent Document 1, since the insulator and the movable contact are assembled so as to be relatively rotatable, wear occurs in the insulator when the movable contact and the insulator are relatively rotated by vibration or the like. . For this reason, the insulator needs to be thick enough to allow for wear, and the axial length of the electromagnetic switch has been increased accordingly.

Moreover, since the impact force when a movable contact collides with a fixed contact is added to an insulator, the intensity | strength which can endure this impact force is requested | required. In particular, when a resin molded product is used for the insulator, it is important to design the strength of the weld portion where the strength is reduced with respect to the normal material strength. That is, it is necessary to design so that the strength of the weld portion can withstand the maximum load applied to the insulator from the movable contact. For this reason, it is necessary to increase the thickness of the insulator in order to ensure the strength of the weld portion, and accordingly, the axial length of the electromagnetic switch has been increased.
The present invention has been made based on the above circumstances, and an object of the present invention is to provide an electromagnetic switch capable of shortening the axial length by reducing the thickness of the insulator.

(Invention of Claim 1)
The electromagnetic switch of the present invention supports a movable contact via an insulator, a plunger attracted by an electromagnetic force, a fixed contact connected to a motor circuit of a starter, a movable contact that moves in opposition to the fixed contact, and an insulator. with a plunger shaft for transmitting the movement of the plunger to the movable contact, is provided between the movable contact and the insulator, an electromagnetic switch and a detent means for restricting the relative rotation therebetween, the movable contact is a fixed contact The insulator is supported so that the load applied to the insulator is maximized when the plunger is attracted by electromagnetic force and the movable contact collides with the fixed contact. This is a resin molded product with a part, and the detent means has a concave shape formed on the movable contact and a shape on the insulator. Is constituted by a concave-convex fitting between been convex, convex shape, characterized in that it is arranged to weld.
According to the above configuration, since the relative rotation between the movable contact and the insulator is restricted by the rotation preventing means, the wear of the insulator can be suppressed. As a result, since it is not necessary to allow for the wear allowance of the insulator, the thickness of the insulator can be made thinner than before, and the axial length of the electromagnetic switch can be shortened.
Further, since the part where the movable contact abuts on the fixed contact is a substantially constant place, the part where the load applied to the insulator from the movable contact when the movable contact collides with the fixed contact is also a substantially constant place. Therefore, in the insulator, the margin in the strength can be improved by arranging the weld portion while avoiding the portion where the maximum load is applied, and accordingly, it is possible to design the insulator with a thin plate thickness. The shaft length of the switch can be further shortened.
Furthermore, by arranging the convex shape of the anti-rotation means in the weld portion, the thickness of the weld portion is increased and the strength of the weld portion is improved, so that the insulator can be made thinner accordingly.
In addition, since the convex shape arranged in the weld portion is unevenly fitted into the concave shape formed in the movable contact, the height of the convex shape (the dimension in the axial direction) does not affect the axial length of the electromagnetic switch. Even if a convex shape is formed on the insulator, the axial length of the electromagnetic switch does not increase.

(Invention of Claim 2 )
2. The electromagnetic switch according to claim 1 , wherein the insulator has a weld portion disposed at a portion where a load applied to the insulator is minimized when the plunger is attracted by electromagnetic force and the movable contact collides with the fixed contact. Features.
In this case, since the weld part having the weakest strength among the insulators can be arranged at a part having the smallest load, the margin in terms of strength can be further improved, and the insulator can be thinned.

(Invention of Claim 3 )
3. The electromagnetic switch according to claim 1, further comprising a contact cover that covers the outside of the fixed contact and the movable contact, and the movable contact is movable in the axial direction in a state in which an outer periphery of the movable contact is prevented from rotating on an inner periphery of the contact cover. It is characterized by doing.
As a result, the movable contact always comes into contact with the fixed contact, so when the movable contact collides with the fixed contact, the portion where the load applied to the insulator from the movable contact is maximum and the portion where the load is minimum are also substantially constant. It becomes.

  The best mode for carrying out the present invention will be described in detail with reference to the following examples.

FIG. 1 is a cross-sectional view of the electromagnetic switch 1.
As shown in FIG. 1, the electromagnetic switch 1 described in the first embodiment includes a switch yoke 2 having a cup shape, an excitation coil 4 wound around a bobbin 3 and accommodated in the switch yoke 2, and a bobbin 3. A plunger 6 inserted into the inner circumference of the plunger 6 through a sleeve 5, a shaft 7 fixed to the plunger 6, a motor contact (described later) for opening and closing a motor circuit of a starter (not shown), and the like. .

The switch yoke 2 is provided with a bottom wall portion 2a having a circular hole at the center in the radial direction, and an outer wall portion 2b extending in a cylindrical shape from the outer periphery of the bottom wall portion 2a and covering the outer periphery of the exciting coil 4. . The switch yoke 2 forms an outer frame (case) of the electromagnetic switch 1 and forms a magnetic circuit around the exciting coil 4 in cooperation with the fixed iron core 8.
The exciting coil 4 includes an attracting coil 4a that generates a magnetic force for attracting the plunger 6, and a holding coil 4b that generates a magnetic force for retaining the attracted plunger 6, and the bobbin 3 has two layers. It is wound.

The sleeve 5 is made of, for example, stainless steel and has a cylindrical shape, and is disposed from the inner periphery of the bobbin 3 to the inner periphery of a round hole that opens to the bottom wall portion 2 a of the switch yoke 2.
The plunger 6 is inserted inside the sleeve 5, moves in the axial direction using the sleeve 5 as a guide surface, and is attached in the anti-core direction (left direction in the figure) by a return spring 9 disposed between the plunger 6 and the fixed core 8. It is energized.

  When the fixed iron core 8 is magnetized by energizing the exciting coil 4, the plunger 6 moves to the right in FIG. 1 while compressing the return spring 9 by the attractive force acting between the plunger 6 and the fixed iron core 8. . Further, when the energization to the exciting coil 4 is stopped and the attractive force disappears, the reaction force of the return spring 9 is received and it is pushed back to the left in FIG. In addition, the upper side from the center line of FIG. 1 shows the operating state of the electromagnetic switch 1, and the lower side of the center line shows the non-operating state of the electromagnetic switch 1.

The shaft 7 is provided with a flange portion 7 a at one end portion, and the end surface of the flange portion 7 a is fixed to the end surface of the plunger 6 by welding or the like, and moves integrally with the plunger 6.
The motor contact is composed of a set of fixed contacts 12 connected to the motor circuit via the two terminal bolts 10 and 11, and a movable contact 13 which is movable facing the set of fixed contacts 12. When the movable contact 13 abuts on both the fixed contacts 12 and conducts between the both fixed contacts 12, the motor contact is closed, and the movable contact 13 is separated from both the fixed contacts 12 and the conduction between the both fixed contacts 12 is cut off. As a result, the motor contact is opened.

  The two terminal bolts 10 and 11 are fixed to a resin contact cover 14, and fixed contacts 12 are provided inside the contact cover 14. As shown in FIG. 1, the contact cover 14 is disposed with a rubber packing 15 sandwiched between the fixed iron core 8 and fixed to the opening of the switch yoke 2 by caulking.

  As shown in FIG. 2, the movable contact 13 is formed of a metal plate (for example, a copper plate) having a substantially constant plate thickness, and the planar shape is provided in a substantially rectangular shape. A round hole 13a larger than the outer diameter of the shaft 7 is opened at the center of the movable contact 13, and a pair of engagement holes 13b are formed on both sides of the round hole 13a in the longitudinal direction of the rectangle. The movable contact 13 is supported by the other end of the shaft 7 via an insulator 16 that is an insulating member, and is urged by a contact pressure spring 17 disposed between the flange portion 7 a of the shaft 7 and the insulator 16. Thus, it is positioned by a stopper 18 attached to the end of the shaft 7. Further, the movable contact 13 has an outer periphery of the movable contact 13 on an inner periphery of the contact cover 14 so that a portion (referred to as a contact portion 13c) on the outer side in the longitudinal direction from the engagement hole 13b can always contact the fixed contact 12. It is prevented from rotating and moves in the axial direction.

  As shown in FIG. 3 (b), the insulator 16 has a circular planar shape, and a round hole 16 a that fits to the outer periphery of the shaft 7 is opened at the center thereof. A cylindrical boss portion 16b is provided around the round hole 16a, and a pair of convex portions 16c are provided on both radial sides of the cylindrical boss portion 16b. As shown in FIG. 3A, the cylindrical boss portion 16 b and the pair of convex portions 16 c are provided so as to protrude on one side (the right side in the drawing) in the plate thickness direction, and the protruding height is the thickness of the movable contact 13. (See FIG. 4).

  As shown in FIG. 4, the movable contact 13 and the insulator 16 are fitted with the cylindrical boss portion 16b of the insulator 16 in the circular hole 13a of the movable contact 13, and the pair of convex portions 16c formed on the insulator 16 are moved to the movable contact. 13 are combined in a state of being fitted into a pair of engaging holes 13b formed in the base plate 13. As a result, the insulator 16 and the movable contact 13 are formed with an anti-rotation means by the concavo-convex fitting between the convex portion 16c and the engagement hole 13b, and the relative rotation of both is restricted.

Next, the operation of the electromagnetic switch 1 will be described.
When the exciting coil 4 is energized and the fixed iron core 8 is magnetized, an attractive force acts between the fixed iron core 8 and the plunger 6, so that the plunger 6 is attracted to the fixed iron core 8 and compresses the return spring 9. While moving to the right in FIG. By this movement of the plunger 6, the contact portion 13 c of the movable contact 13 supported by the end portion of the shaft 7 comes into contact with the fixed contact 12 and the motor contact is closed.
Thereafter, when the energization to the exciting coil 4 is stopped, the attraction force disappears, and when the plunger 6 is pushed back to the left in FIG. 1 by the reaction force of the return spring 9, the movable contact 13 is separated from the fixed contact 12, and the motor The contact is opened.

(Effect of Example 1)
In the electromagnetic switch 1 of this embodiment, the relative rotation between the insulator 16 and the movable contact 13 is restricted by the concave and convex fitting between the convex portion 16 c formed in the insulator 16 and the engagement hole 13 b formed in the movable contact 13. ing. Thereby, since the insulator 16 and the movable contact 13 are not rubbed in the circumferential direction due to vehicle vibration or the like, wear of the insulator 16 can be suppressed. As a result, since it is not necessary to allow the wear allowance of the insulator 16, the plate thickness of the insulator 16 can be made thinner than before, and the axial length of the electromagnetic switch 1 can be shortened accordingly.

In the second embodiment, an example in which the insulator 16 is a resin molded product will be described.
The movable contact 13 described in the first embodiment is movable in the axial direction with its outer periphery being prevented from rotating to the inner periphery of the contact cover 14, so that the portion that contacts the set of fixed contacts 12 is always at a constant location (see FIG. 2).

  When the plunger 6 is attracted by electromagnetic force and the movable contact 13 collides with the fixed contact 12, the impact force is applied to the insulator 16 via the movable contact 13. At this time, the portion of the movable contact 13 that contacts the fixed contact 12 is always a fixed place (contact portion 13c), and the relative rotation between the movable contact 13 and the insulator 16 is restricted. The part where the load becomes the largest is also a substantially constant place. That is, when the movable contact 13 collides with the fixed contact 12, the insulator 16 receives a load on both sides in the radial direction where the pair of convex portions 16 c are formed, so that the cylindrical boss portion 16 b shown in FIG. The largest load is applied to the left and right sides.

When a resin molded product is used for the insulator 16, the arrangement of the weld portion W is important in terms of strength design. That is, when the largest load is applied to the weld portion W that is the weakest in strength, the weld portion W needs to be strong enough to withstand the maximum load, and the thickness of the insulator 16 is inevitably increased. It will be thick. On the other hand, if the weld portion W is arranged avoiding the portion where the largest load is applied, a margin in strength can be obtained.
Therefore, in the insulator 16 shown in the second embodiment, the weld portion W is arranged so as to avoid the portion where the maximum load is applied (the left and right sides of the cylindrical boss portion 16b shown in FIG. 3B). More preferably, as shown in FIG. 3B, the weld portion W may be disposed at a portion where the load applied to the insulator 16 is minimized, that is, at a portion where the pair of convex portions 16c are formed.

As described above, when a resin molded product is used for the insulator 16, since the weld portion W is disposed so as to avoid the portion where the maximum load is applied, the margin in terms of strength can be improved. Therefore, the axial length of the electromagnetic switch 1 can be further shortened. In particular, when the weld portion W is disposed at a portion where the load applied to the insulator 16 is minimized, the convex portion 16c is formed at that location, so that the thickness of the weld portion W increases and the weld portion W Since the strength is improved, the insulator 16 can be further thinned.
In addition, since the convex part 16c formed in the insulator 16 is unevenly fitted in the engaging hole 13b formed in the movable contact 13, the height (axial dimension) of the convex part 16c is the axial length of the electromagnetic switch 1. The axial length of the electromagnetic switch 1 does not increase even if the weld portion W is arranged at the portion where the convex portion 16c is formed.

(Modification)
In the first embodiment, an example in which the planar shape of the movable contact 13 is a substantially rectangular shape has been described. However, the shape is not limited to a substantially rectangular shape, and any shape that can be prevented from rotating by the inner periphery of the contact cover 14 may be used. Alternatively, the insulator 16 is prevented from rotating with respect to the shaft 7 and the plunger 6 to which the shaft 7 is fixed is prevented from rotating (for example, the plunger 6 has an elliptical cross-sectional shape, and the elliptical sleeve 5 also serves as a plunger 6). In other words, the planar shape of the movable contact 13 can be circular.

  In Example 2, although the example which uses a resin molded product for the insulator 16 was described, in Example 1, it is not necessary to limit the material of the insulator 16 to resin. That is, in Example 1, since the wear of the insulator 16 is prevented by restricting the relative rotation between the insulator 16 and the movable contact 13, the material of the insulator 16 may be resin, but an insulating material other than resin ( Cork, ceramic, wood, etc.), or a conductor surface coated with an insulating material (insulating paint, etc.) can also be used.

It is sectional drawing of an electromagnetic switch. (A) It is sectional drawing of a movable contact, (b) It is a top view of a movable contact. (A) It is sectional drawing of an insulator, (b) It is a top view of an insulator. (A) Sectional drawing of the state which combined the insulator and the movable contact, (b) The same top view.

Explanation of symbols

1 Electromagnetic switch 6 Plunger 7 Shaft (plunger shaft)
12 Fixed contact 13 Movable contact 13b Engagement hole (concave shape formed in movable contact, anti-rotation means)
14 Contact cover 16 Insulator 16c Convex part (convex shape formed on the insulator, anti-rotation means)
W Weld

Claims (3)

A plunger attracted by electromagnetic force;
A fixed contact connected to the motor circuit of the starter;
A movable contact that is movable in opposition to the fixed contact;
A plunger shaft for supporting the movable contact via an insulator and transmitting the movement of the plunger to the movable contact;
Provided between the insulator and the movable contact, an electromagnetic switch and a detent means for restricting the relative rotation therebetween,
The movable contact is supported so that the portion that contacts the fixed contact is a substantially constant place,
The insulator is a resin molded product in which a weld portion is arranged to avoid a portion where the load applied to the insulator is maximum when the plunger is attracted by electromagnetic force and the movable contact collides with the fixed contact.
The anti-rotation means is constituted by a concave-convex fitting of a concave shape formed on the movable contact and a convex shape formed on the insulator, and the convex shape is arranged in the weld portion. Electromagnetic switch to do. The electromagnetic switch according to claim 1 ,
In the insulator, when the plunger is attracted by electromagnetic force and the movable contact collides with the fixed contact, the weld portion is disposed at a portion where the load applied to the insulator is minimized. switch. The electromagnetic switch according to claim 1 or 2 ,
A contact cover covering the fixed contact and the movable contact;
The electromagnetic switch characterized in that the movable contact is movable in the axial direction in a state in which an outer periphery of the movable contact is prevented from rotating on an inner periphery of the contact cover.

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