JPH01225027A - Contact structure of magnetic switch for starter - Google Patents

Abstract

PURPOSE:To mitigate the contact collision and make a magnetic switch small- sized by allowing an elastic body to participate in the collision of a contact and absorbing the kinetic energy of a movable contact with this elastic body. CONSTITUTION:When a starter is turned on and a magnetic switch is excited, the magnetic flux is generated by an exciting coil, a plunger 2 is sucked by the action of this magnetic flux, simultaneously a shaft 8 is extruded. The shaft 3 extrudes a movable contact 4 via a push spring against the resistance of a shaft return spring 7, the collision of contacts occurs. The movable contact 4 is repulsed by the reaction force of the collision, a force to push back the shaft via the push spring 6 is generated, this is absorbed by using an elastic body 8 such as rubber. The jumping of the contact is thereby prevented, the abrasion of the contact area is reduced, the magnetic switch is made small-sized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a contact mechanism of a magnetic switch for a starter, and particularly to a structure suitable for reducing wear on contact surfaces and downsizing the magnetic switch.

[Conventional technology]

The conventional device, as described in Utility Model Application Publication No. 60-5045,
In the starter's magnetic switch, only a push spring was used to cushion the contact between the fixed and movable contacts.

[Problem to be solved by the invention]

The above conventional technology does not take into consideration the repulsive force caused by collisions between metal pieces, and the kinetic energy of the bounce due to the repulsive force is stored in the push spring as potential energy, and is then transferred back to the movable contact with approximately the same kinetic energy. It was structured to give As this process is repeated, a large current momentarily flows through the contacts. This causes problems with damage and welding of the contact contact surface, and the spring force of the contact return spring becomes large for the purpose of disassociation, and a large suction force is required to ensure smooth operation, making the magnetic switch larger. There was a drawback.

An object of the present invention is to alleviate contact collisions, and also to reduce the size of a magnetic switch.

[Means to solve the problem]

The objective is achieved by involving an elastic body in the collision of the contacts and by this elastic body absorbing the kinetic energy of the movable contact.

[Effect]

The elastic body operates to absorb reaction force that acts on the movable contact when the contact contacts. This reduces reaction force and prevents jumping, thereby preventing malfunctions such as wear and welding of contact surfaces.

Furthermore, since there is no need to push the contacts apart as described above, the spring force of the contact push spring can be reduced, and the suction force can be set low.

Therefore, the magnetic switch can be made smaller.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in Section 1. This will be explained using Figure 2, 3.4.

1 is an excitation coil, 2 is a plunger, 3 is a movable contact shaft (hereinafter referred to as shaft), 4 is a movable contact, 5 is a fixed contact, 6
7 is a push spring, 7 is a shaft return spring, and 8 is an elastic body made of rubber, which is incorporated into the plunger.

When the magnetic switch is energized when the starter is turned on, a magnetic flux is generated by the excitation coil 1, and the action of this magnetic flux attracts the plunger 2 and pushes out the shaft 3 at the same time. The shaft 3 pushes out the movable contact 4 via the push spring while receiving resistance from the shirt 1 return spring 7, and a collision of the contacts occurs as shown in FIG. 2. The movable contact 4 bounces due to the reaction force of the collision, and a force that tries to push back the shaft acts through the push spring 6, but this is absorbed by using the elastic body 8. FIG. 3 illustrates this state.

Also, the model of this dynamical system is shown in Figure 4, and K
1 is the spring constant of the elastic body, and K2 is the spring constant of the push spring. Conventionally, the push spring spring constant was set to a small value of 2 for the purpose of buffering, but in this case, the opposite kinetic energy obtained by the movable contact 4 due to the repulsion caused by the collision of the metal contacts is stored as potential energy of the spring. The operation of applying approximately equal kinetic energy to the movable contact 4 is repeated again. In order to reduce this kinetic energy in a short time and to reduce the amplitude, it is necessary to give a more appropriate value to the spring constant 2. Furthermore, since the resistance between the contacts is inversely proportional to the square of the contact pushing spring load, it is necessary to give 2 a larger value than in conventional products. Therefore, by providing an elastic body with a spring constant of 1 in series, we obtain the spring constant K of this system, which is = KIXK2/ (2 to K'l+), and obtain the optimal operation in contact collision and contact closed states. .

In the prior art, when a contact becomes welded due to an instantaneous high current during jumping, the thick spring force of the contact return spring is used to separate the contact. Since the spring force of the contact return spring is large, a large suction force is required, and the mag switch is large. On the other hand, according to the present invention, since jumping can be avoided and the above-mentioned large attraction force is not required, the magnetic switch can be made smaller.

〔Effect of the invention〕

According to the present invention, since jumping of the contacts of the magnetic switch can be prevented, there are effects of reducing wear on the contact surfaces of the contacts and downsizing the magnetic switch.

[Brief explanation of the drawing]

Figure 1 is an axial cross-sectional view of the magnetic switch according to the present invention, and Figures 2 and 3 are cross-sectional structures when the contacts are in contact and when the bouncing (jumping) of the movable contact due to reaction force is alleviated by an elastic body. 4 are diagrams showing a modeled dynamical system. DESCRIPTION OF SYMBOLS 1... Coil, 2... Plunger, 3... Movable contact shaft, 4... Movable contact, End... Fixed contact, 6...
...Push spring, 7...Shaft return spring, 8...
・Elastic body.

Claims (1)

[Claims] 1. In a starter magnetic switch having a fixed core, a plunger (movable core), a coil, and a contact mechanism, a member having springiness with a spring coefficient K1 is attached to the plunger, and a contact shaft is arranged relative to the member. It consists of a movable contact attached via a spring with a spring constant K2 (K2>K1), and a fixed contact disposed between the movable contact and a predetermined gap, and when the contacts make contact, the spring and the elastic body are arranged in series. Contact structure of a magnetic switch for starters.