JPH0583993U - Electromagnetic switch - Google Patents

Abstract

(57) [Abstract] [Purpose] To increase the magnetic attraction force when starting the electromagnetic switch. [Structure] Between a plunger 6 and a plunger rod 12, a magnetic body 22 urged by a return spring 23 so as to be slidable with respect to each other and away from each other.
To provide. Therefore, the plunger 6 and the plunger rod 1
2 is magnetically bridged, a magnetic closed circuit is formed by the yoke 2, the plunger 6, the magnetic body 22, the plunger rod 12, and the fixed iron core 5, and the generation of leakage magnetic flux is suppressed. Power increases.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an electromagnetic switch, and more particularly to an improvement of an electromagnetic switch suitable for an engine starter.

[0002]

[Prior Art]

 As an electromagnetic switch used for on / off control of the engine starter motor, a type that opens and closes electrical contacts in conjunction with the reciprocating motion of the electromagnetic plunger for axially shifting the pinion gear that meshes with the engine ring gear. It has been known. In such an electromagnetic switch, since the pinion gear needs to be shifted with a certain amount of movement, the plunger is reciprocated with a predetermined size.

In the type in which the plunger and the contact mechanism are integrally formed, since the plunger reciprocates a predetermined amount, a fixed contact and a movable member equivalent to the plunger stroke as the predetermined amount are movable. Since the distance between the contact and the contact is required, increasing this distance has been a disadvantage in making the electromagnetic switch compact.

Therefore, in order to realize a compact electromagnetic switch, a plunger rod is generally slidable between the plunger and the movable contact point with a predetermined gap between the plunger and the movable contact point, and is slidable in the center of the fixed iron core. Has been pierced. A fixed contact is provided at the end of the plunger rod that projects from the fixed iron core so that the distance between the contacts is smaller than the plunger stroke.

However, according to the type using the plunger rod, since a predetermined gap is formed between the plunger and the plunger rod, the magnetic closed circuit formed by the magnetic substance is formed by the gap. Will be cut off, which will change the flow of magnetic flux and cause leakage flux. Therefore, inevitably, the attraction force tends to decrease during the period until the plunger contacts the plunger rod, that is, when the electromagnetic switch is started.

[Problems to be solved by the device]

 The present invention has been devised to solve such problems of the conventional technology, and its main purpose is to provide an electromagnetic switch that can obtain a large magnetic attraction force at the time of starting the electromagnetic switch. is there.

[0006]

[Means for Solving the Problems]

 According to the present invention, such a purpose is to provide a bottomed cylindrical iron core yoke assembly, a hollow coil coaxially wound in the iron core yoke assembly, and a hollow core coil assembly that can be retracted from the open end of the iron core yoke assembly. And a plunger rod that penetrates through the center of the bottom of the iron core yoke assembly so that it can contact the inner end of the plunger and the first end when the hollow coil is excited. An electromagnetic switch of the type described above, which selectively excites a hollow coil to drive a contact mechanism provided at a second end of the plunger rod that is opposite to the first end of the plunger rod. A magnetic bridging means is provided between the first end portion and the inner end of the plunger, the magnetic bridging means being slidable with respect to each other and spring-biased so as to separate the portions from each other. Electromagnetic It is achieved by providing a pitch.

[0007]

[Action]

 According to this structure, since the plunger and the plunger rod are magnetically bridged by the magnetic bridging means, a magnetic closed circuit is formed and the magnetic flux can flow through the magnetic closed circuit. Therefore, leakage of magnetic flux can be minimized. Therefore, the suction force at the time of starting can be increased as compared with the conventional case.

[0008]

【Example】

 Hereinafter, the structure of the present invention will be described in detail with reference to specific embodiments shown in the accompanying drawings.

FIG. 1 is a vertical cross-sectional view of an electromagnetic switch for a starter motor constructed according to the present invention. This electromagnetic switch 1 includes a yoke 2 as a cylindrical portion of an iron core yoke assembly, an exciting coil 3 received in the yoke 2, an end cover 4 closing an opening end of the yoke 2, and an axial end of the exciting coil 3. It is sandwiched and fixed between the end cover 4 and the end cover 4, and a fixed iron core 5 as the bottom of the iron core yoke assembly having a part thereof immersed in the inner circumference of the excitation coil 3 and the fixed iron core 5 are coaxially opposed to each other. In addition, it has a plunger 6 which is attracted to the fixed iron core 5 by energizing and exciting the exciting coil 3 and which can be axially displaced at the inner peripheral portion of the exciting coil 3.

The excitation coil 3 includes a suction coil 3a formed by winding a conductor having a relatively large diameter on the inner peripheral side and a holding coil 3b formed by winding a conductor having a relatively small diameter on the outer peripheral side. The switch terminals 8 connected to one ends of the coils 3a and 3b are drawn out of the end cover 4 made of an insulating material. An ignition switch (not shown) is electrically connected to the switch terminal 8. The other end of the holding coil 3b is grounded via the fixed iron core 5, and the other end of the suction coil 3a is connected to a fixed contact 9 for a motor connection terminal fixedly mounted on the inner wall surface of the end cover 4. .. Further, on the inner wall surface of the end cover 4, fixed contacts 10 for battery connection terminals are provided in parallel with fixed contacts 9 for motor connection terminals.

A guide hole 11 penetrating in the axial direction is provided in the center of the fixed iron core 5, and a plunger rod 12 is slidably inserted in the guide hole 11. A stopper member 13 made of an insulating material and a movable contact member 14 made of a conductor are fitted to the end of the plunger rod 12 projecting from the fixed iron core 5 toward the end cover 4 so as to be axially displaceable. Between the end of the rod 12 and the inner surface of the end cover 4, a return spring 15 for urging the plunger rod 12 so as to be retracted into the guide hole 11 is contracted.

The plunger rod 12 is composed of a small-diameter portion 12a that slides into the guide hole 11 of the fixed iron core 5 and a large-diameter portion 12b into which the stopper member 13 and the movable contact member 14 are fitted. It is molded. Then, an intermediate flange 16 is formed integrally between the small diameter portion 12a and the large diameter portion 12b in the shape of an ellipse having the short diameter of the small diameter portion 12a and the long diameter of the large diameter portion 12b. In addition, an end flange 17 that prevents the movable contact member 14 from coming off and a holding portion of the return spring 15 is integrally formed at the end of the large diameter portion 12b. Further, between the intermediate flange 16 and the stopper member 13, a contact spring 18 composed of a conical coil spring for elastically biasing the movable contact member 14 toward the end flange 17 side is provided in a contracted manner. There is.

Further, the small-diameter portion 12 a of the plunger rod 12 is formed with an axial hole 21 that opens at a predetermined depth on the end surface facing the plunger 6. Inside the axial hole 21, a magnetic body 22 as a cylindrical magnetic bridging means having an axial length longer than the gap between the plunger 6 and the plunger rod 12 in the demagnetized state is provided. It is provided in the inserted state. A return spring 23 is provided in the axial hole 21 to bias the magnetic body 22 in a protruding direction. It is designed to abut. Then, the plunger return pulling 19 causes the plunger 6 to return to its original position when the exciting coil 3 is demagnetized. Further, the plunger rod 12 is pushed toward the end cover 4 side while the return pulling 23 is compressed by the plunger 6 which is attracted and displaced by the fixed iron core 5 when the exciting coil 3 is excited.

In the electromagnetic switch 1 configured as described above, the plunger 6 is attracted to the fixed iron core 5 by energizing the exciting coil 3. When the plunger 6 is displaced while the magnetic body 22 is being received in the axial hole 21 of the plunger rod 12 as the plunger 6 is displaced toward the iron core 5, the movable contact member 14 is fixed on both sides accordingly. It is displaced so as to come into contact with the contacts 9 and 10, and the fixed contacts 9 and 10 are electrically bridged, so that the current from the battery flows to the DC motor. When the excitation coil 3 is de-energized, the plunger 6 is returned to its original position by the elastic force of each return spring 15.19.23, and the plunger rod 12 and the magnetic body 22 are returned to its original position. The movable contact member 14 separates from the fixed contacts 9 and 10.

Here, for example, as seen in the conventional electromagnetic switch, the magnetic body 22 does not exist between the plunger 6 and the plunger rod 12, that is, there is a gap between the plunger 6 and the rod 12 during demagnetization. Since the magnetic path is formed through this air gap, it is conceivable that the flow of the magnetic flux changes in the air gap and some leakage magnetic flux is generated.

Therefore, in the present invention, as shown in FIG. 1, the plunger 6 and the plunger rod 12 are magnetically bridged by using the magnetic body 22. According to this, since the magnetic closed circuit is formed by the yoke 2, the plunger 6, the magnetic body 22, the plunger rod 12, and the fixed iron core 5, the generation of leakage magnetic flux is suppressed as compared with the electromagnetic switch assumed above. Therefore, as shown in FIG. 2, in the case where the gap formed between the plunger 6 and the fixed iron core 5 is large, that is, the attraction force at the start of the electromagnetic switch is increased.

FIG. 3 is a view showing another embodiment of the magnetic bridging means as an essential part of the present invention, and FIG. 3 (a) shows that the magnetic body 22 of the above embodiment is integrated with the plunger 6. 3 (b), an axial hole 21 is formed in the end face of the plunger 6 facing the plunger rod 12 to form the plunger rod 12 in the axial direction. Is extended to the axial hole 21 and received in the axial hole 21 to serve as a magnetic bridging means. Further, FIG. 3 (c) shows an axial hole in the end face of the magnetic body 22 facing the plunger rod 12. 21 is formed, and the plunger rod 12 is received in the axial hole 21 to serve as a magnetic bridging means. Whichever type is adopted, the same effect as that of this embodiment is obtained. Can be played.

[0018]

As described above, according to the present invention, since the magnetic field is magnetically bridged between the plunger and the plunger rod, it is possible to suppress the generation of leakage magnetic flux. Therefore, the initial magnetic attraction force can be increased, and the responsiveness at the time of starting the switch can be improved. In addition, the magnetic attraction force can be increased with the conventional physique without changing the plunger stroke or the distance between contact points in the contact mechanism. Therefore, it is extremely effective in improving the operational reliability of this type of electromagnetic switch.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an electromagnetic switch according to the present invention.

FIG. 2 is a diagram showing characteristics of FIG. 1 and a conventional electromagnetic switch.

FIG. 3 is an enlarged sectional view of an essential part showing another example of the essential part of the present invention.

[Explanation of symbols]

 1 Electromagnetic Switch 2 Yoke 3 Excitation Coil 4 End Cover 5 Fixed Iron Core 6 Plunger 8 Switch Terminal 9 Motor Connection Terminal Fixed Contact 10 Battery Connection Terminal Fixed Contact 11 Guide Hole 12 Plunger Rod 13 Stopper Member 14 Moving Contact Member 15 Return Spring 16 Intermediate flange 17 End flange 18 Contact spring 19 Plunger return spring 21 Axial hole 22 Magnetic material 23 Return spring

Claims (1)

[Scope of utility model registration request] 1. An iron core yoke assembly having a bottomed tubular shape, a hollow coil coaxially wound in the iron core yoke assembly, and a plunger received and retracted from an open end of the iron core yoke assembly. A plunger rod penetrating the center of the bottom of the iron core yoke assembly so as to be able to contact the inner end of the plunger and the first end when the hollow coil is excited; In an electromagnetic switch of a type that is excited by a magnetic field to drive a contact mechanism provided at a second end opposite to the first end of the plunger rod, the electromagnetic switch including the first end and the inner end of the plunger. An electromagnetic switch characterized in that a magnetic bridging means, which is slidable with respect to each other and spring-biased in a direction to separate the two parts from each other, is provided between the two.