JPH037011Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Field of industrial application This invention relates to an improvement in a small switch that protects electronic equipment from excessive current by interrupting the circuit when excessive current flows.

(b) Prior Art As shown in FIG. 4, a conventional small switch of this type has a base 11A of a bimetal 11 with a movable contact 12 attached near its free end, which is protruded into and out of a case 14. 1 terminal 13, and an arcuate spring 15 is connected to the free end 11B of the bimetal 11.
One end 15A is engaged so as to apply a biasing force toward the base of the bimetal 11, and the movable contact 12 is connected to the second terminal 17 at one of two stable points (indicated by a solid line and a two-dot chain line) of the bimetal 11. While the movable contact 12 and the fixed contact 16 are held in pressure contact with the fixed contact 16 attached near the free end, the movable contact 12 and the fixed contact 16 are separated at the other stable point. Since the spring 15 applies a biasing force in the base direction to the bimetal 11, if the junction between the spring 15 and the bimetal 11 exceeds the critical line A even slightly, it immediately moves to another stable position, and this bimetal 11 itself Since the contacts 12 and 16 are opened and closed by the movement of It has the features that can be obtained.

However, in the above-mentioned switch, since the direction in which the bimetal 11 is deformed, that is, the direction of the arrow P, coincides with the opening direction of the contacts 12 and 16, the bimetal 11 is gradually deformed and the spring 15 and the bimetal 11 are separated. Until the junction point of reaches the critical line A,
The contact pressure between contacts 12 and 16 becomes unstable. This has the disadvantage that there is a risk of poor conduction and circuit malfunction.

(c) Problems to be solved by the invention This invention was created in consideration of the above-mentioned points, and when separating the movable and fixed contacts, the bimetal should be constructed so that the direction of deformation coincides with the direction in which the contacts are pressurized. Our first objective was to obtain a highly reliable switch of this type that can maintain a stable contact state between the contacts under any circumstances. The second purpose is to obtain a device.

(d) Means for solving the problem This invention consists of first and second terminals each having a terminal protruding from the outside of the case, and a plate spring member whose base is fixed to the first terminal and movable near the free end. In addition to attaching a contact, a fixed contact is attached near the free end of the bimetal whose base is connected to the second terminal, and a midsection of the plate spring member is attached so as to apply a biasing force in the direction of the movable contact attachment side of the plate spring member. One end of an arcuate spring formed by punching is locked to the first terminal, and the movable and fixed points are fixed at one of two stable points of the free end of the leaf spring member caused by deformation of the bimetal. The two contacts are held in pressure contact, and the fixed and movable contacts are separated from each other, while the engaging portion inside the case of the presser, which can be operated from outside the case, is connected to the plate spring member. The plate spring member can be set from one stable point to the other stable point based on the push/pull action of the pusher.

(e) Effect This device is configured so that the deformation direction of the bimetal due to overcurrent acts in the direction in which pressure contact force is applied to both the movable and fixed contacts. The contact state between the contacts can be maintained stably without weakening. Further, the number of component parts is reduced by forming an arcuate spring in the leaf spring member itself by punching and applying a biasing force of the arcuate spring between both contact points.

(f) Embodiment FIG. 1 is a front view of a small switch according to an embodiment of this invention, FIG. 2 is a plan view thereof, and FIG. 3 is an explanatory diagram of the operation. In Fig. 1, numeral 1 denotes a resin insulating case with the front cover removed. Reference numeral 2 denotes a leaf spring member, and a window hole 20 whose plane is approximately shaped is provided in the midsection of the leaf spring member.
A substantially rectangular window hole 22 is punched out between the bridging pieces 21, and an arcuate spring 23 is formed in the remaining portion where the window hole 20 is punched. Further, a movable contact 3 is fixed to one free end of the leaf spring member 2 by caulking. Then, the plate spring member 2
is a lock formed on one side edge of a support part 40 that protrudes in and out of the case and has a substantially shaped flat surface on the upper side of the first terminal 4, which is erected at approximately the center of the case. The proximal end 24 of the leaf spring member is locked in the groove 41, and the free end 23A of the arcuate spring 23 is locked in the locking groove 42 formed on the other side edge. The locking grooves 41 and 42 are formed such that the position of one of the locking grooves 41 is slightly higher than the position of the locking groove 42, and usually,
When the leaf spring member 2 is locked to the first terminal 4, a biasing force is applied to the leaf spring member by the arcuate spring 23 in the direction of arrow _P1 , that is, in the mounting direction of the contact 3, as shown in FIG. I've made it so that I can join. Reference numeral 5 denotes a bimetal with a roughly shaped cross section, whose base end is fixed by caulking with a rivet 7 to the tip of a second terminal 6 protruding inside and outside the case, and the fixed contact 8 is fixed to the movable contact 3 on the free end side. It is attached by caulking to the part facing the. 9 is a third terminal protruding from inside and outside the case, and a fixed contact 10 is attached to the free end of the case.
is fixed. In such a device, under normal conditions, the contact 3 is in pressure contact with the contact 8 side at the first stable point (solid line position in Figure 1) due to the biasing force of the arcuate spring 23, and as will be described later, overcurrent is generated. The bimetal is deformed by the flow, and when the leaf spring member 2 is reversed and is at the second stable point (the position indicated by the two-dot chain line in FIG. 1), the contact 3 is pressed against the fixed contact 10. Note that the third terminal 9 and the fixed contact 10 may be removed if they are unnecessary. Reference numeral 18 denotes a presser made of an insulating material such as resin, and the bridging piece 21 of the leaf spring member 2 is hooked to a cutout groove 18A formed in the lower midsection of the presser to support it within the case. The upper end is connected to the opening 1A on the top surface of case 1.
It faces the top end surface. If necessary, a handle portion 18B is formed at the upper end of the pusher 18 so that the handle portion 18B protrudes from the upper end surface of the case 1, and the plate spring member 2 is moved from one of the stable points by a push/pull operation from outside the case. It may be possible to set it to the other stable point. Reference numeral 19 denotes a barrier having a corrugated portion formed on its lower surface, and is integrally formed in the case 1 for the purpose of insulating the plate spring member 2 and the bimetal 5.

Next, the operation will be explained. In a normal state, the switch according to this invention is arranged so that the leaf spring member 2 is at the solid line position in FIG. 1 (first stable point). In this position, as mentioned earlier, the elastic force of the arcuate spring 23 is acting in the direction of arrow _P1 ,
Therefore, a downward pressing force M ₁ is acting on the contact 3 as shown in FIG. 3(1). Next, if an overcurrent flows between terminals 4 and 6 due to an accident, etc.,
The bimetal 5 gradually deforms upward from the state shown in _FIG . While maintaining the state in which force is applied in the direction of mutual pressure, the leaf spring member 2
is displaced upward. The leaf spring member 2 is shown in Fig. 3 (2).
After passing the position shown in FIG. 1, the arcuate spring 23 momentarily reverses itself to the state shown in FIG. becomes. At this time, contact 3 cuts off contact with contact 8 to protect the faulty circuit, while contacting contact 10 with an upward pressing force M ₁ . Next, when the cause of the accident due to overcurrent is removed and the original state is restored, press the pusher 18 that protrudes from the top of the case.
The bridging piece 21 whose tip is pressed and hooked into the groove 18A
The leaf spring member 2 is returned to the first stable point via the .

(g) Effect of the device This device is configured so that the deformation direction of the bimetal due to overcurrent acts in the direction in which pressure contact force is applied to both the movable and fixed contacts, so that contact between the contacts is maintained until the two contacts are about to open. The pressure does not weaken and the contact state between the contacts can be maintained stably, increasing the operational reliability of the switch.
In addition, an arcuate spring is formed by punching the leaf spring member itself, and the biasing force of the arcuate spring is applied between both contacts, which reduces the number of component parts and contributes to lower product costs. It has a powerful effect.

[Brief explanation of drawings]

Figure 1 is a front view of a small switch according to an embodiment of this invention, with the front cover removed, Figure 2 is a plan view with the top cover removed, and Figure 3 is a board. FIG. 4, which is an explanatory diagram of the operation of the spring member, is a longitudinal sectional front view of a conventional small switch. DESCRIPTION OF SYMBOLS 1... Case, 2... Leaf spring member, 23... Arcuate spring, 3... Movable contact, 4... First terminal, 41
... Locking groove, 5 ... Bimetal, 6 ... Second terminal, 8, 10 ... Fixed contact, 9 ... Third terminal, 1
8...Press element.

Claims (1)

[Claims for Utility Model Registration] (1) First and second terminals each having a terminal protruding from the outside of the case, and a movable contact installed near the free end of a leaf spring member whose base is locked to the first terminal. At the same time, a fixed contact is attached near the free end of the bimetal whose base is connected to the second terminal, and a punch is formed in the midsection of the leaf spring member so as to apply a biasing force in the direction of the movable contact attachment side of the leaf spring member. One end of the formed arcuate spring is locked to the first terminal, and deformation of the bimetal occurs at one of two stable points of the free end of the leaf spring member due to deformation of the bimetal due to overcurrent. By making the direction match the direction of pressure contact between the movable and fixed contacts, both the movable and fixed contacts are held in pressure contact, and on the other hand, the fixed and movable contacts are separated from each other. An engaging portion inside the case of a pusher that can be operated from the center is engaged with the plate spring member, and the plate spring member is moved from one stable point to the other stable point based on the push/pull action of the pusher. A small switch characterized by being able to be set. (2) A utility model registration claim characterized in that a third terminal is provided, a fixed contact is attached to the terminal, and a movable contact is held in pressure contact with the fixed contact at the other stable point of the leaf spring member. Range 1
Small switch as described in section.