JPS6222325A - Swtich - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a switch that switches on and off an electric current. The main applicable switches of the present invention include, for example, electromagnetic contactors and molded circuit breakers.

[Conventional technology]

First, an example of a conventional electromagnetic contactor will be described with reference to FIG. In Figure 3, (1) is a mounting base made of plastic, (2) is a fixed core laminated with silicon steel plates on this mounting base, and (31 is a fixed core installed opposite to fixed core (2)). (4) is a movable core laminated with silicon steel plates, and (4) is an operating coil that provides a driving force to attract the movable core (3) and fixed core (2) against a tripping spring (not shown). (5) is a crossbar made of plastic, and its lower end fully holds the movable iron core (3).

A movable contact (6) is pressed by a pusher spring (7) and is in contact with one end of the crossbar (5). (6A)
, (6B) is a movable contact provided on the movable contact (6), and (8) is a fixed contact provided opposite to the movable contact (6) to conduct current, (8A).

(8B) is a fixed contact provided on this fixed contact (8).

(8C) and (8D) indicate terminals. (9) is a terminal screw for connecting the electromagnetic contactor body to an external circuit, αII
I is a pace on which the fixed contact (8) is attached, and αυ is a cover that covers the upper surface of the electromagnetic contact.

(13D) is an insulating plate fixed to the movable contact (6), α
J is provided between this insulating plate (13D) and the cover αυ.
Spiral shape memory alloys, (13A) and (13B)
) indicates both ends of shape memory alloy α3, and one end (13
A) is connected to one end of the conductor I passing through the cover αυ,
Therefore, it is connected to the fixed contact (81).The other end (1!iB) of the shape memory alloy 0 is connected to the conductor α passing through the cover αυ.
It is connected to the terminal (8C) via 5. Terminal (8
The current flowing from conductor α milk shape memory alloy 0° conductor α4. Fixed contact (8A), fixed contact (8A), movable contact (tsA), movable contact (6), movable contact (6)
B), the fixed contact (8B), and the fixed contactor (8) all pass through the other terminal (8D) to the external circuit.

FIG. 4 is a wiring diagram showing the main parts of FIG. 3. In Figure 4, αe is a contact device, which is the fixed contact (8A) in Figure 3.
, (8B), fixed contact (8), movable contact (6A
).

(6B) shows the movable contact (6) all at once.

1fc.

4 (13 is the shape memory alloy of FIG. 3).

In addition, one end (13A/) of the shape memory alloy α3 is attached to the cover α
0 and the other end (13B) are mechanically connected to an insulating plate (IAD).

Further, an arc extinguishing device may be provided within the cover.

Because of the above configuration, in this conventional electromagnetic contactor, when the operation coil (4) is demagnetized, the movable core (3) is separated from the fixed core (2) by a tripping spring (not shown), and the crossbar (5) also occupy the state shown in Fig. 3, with fixed contacts (8A), (8B) and movable contact (6A).
.

(6B) is opened and fixed contacts (8A) and (8B)
An arc α2 occurs between the movable contacts (6A) and (6B).

This arc α2 is extinguished at the current zero point, and the current is cut off.

The above is normal operation, but if a large current flows, the helical shape memory alloy α3 will be heated, and when it exceeds the transformation temperature, it will contract and pull up the movable contact (6), so the movable contact (6A) , (6B) is the fixed contact (8A).

(8B) opens and an arc (Lz) is generated, but this arc α2 is extinguished at the current zero point and the current is cut off.The movable contacts (6A) and (6B) When cooled, the movable contacts (SA), (6B) are closed by the push spring (7), so the movable contacts (6A),
(6B) It is sufficient to maintain the open state.

[Problems solved by the invention]

Since the conventional switch is configured as described above, when the current applied increases, the temperature rise of the shape memory alloy α increases, and the shape memory effect of the shape memory alloy 13 is lost.
There was a problem that normal operation could no longer be performed.

Further, since the shape memory alloy 0 is made of Ni, Ti, etc. and has a high specific resistance, there is a problem in that the loss caused by the application of load current is large.

Furthermore, when an abnormally large current flows, shape memory alloy A3
There was a problem that it would melt.

This invention was made to solve the above-mentioned problems, and it is possible to use a simple method to prevent loss of shape memory or melting of a heat deformable element such as a shape memory alloy when a large current is applied, and also to The purpose is to obtain a switch that can reduce loss during energization.

[Means for solving problems]

The switch according to the present invention is configured such that a contact and a heat deformable element are connected in series, and the contact is opened by deforming the heat deformable element when a large current flows. It is equipped with resistors connected in parallel.

[Effect]

The resistor in this invention shunts the current flowing through the thermal deformable element, thereby preventing the thermal deformable element from melting or losing its shape memory due to a large current flowing through the thermal deformable element. Also,
Since the resistor is connected in parallel with the thermal deformable element, the resistance between the terminals is lower than in the case of only the thermal deformable element, and the loss when normal load current is applied is reduced.

〔Example〕

An embodiment of the present invention will be described below.

In FIG. 1, αη is a resistor. Namely.

3 and 4, except that a resistor αD is connected in parallel with the shape memory alloy αJ, which is a thermal deformation element.
This is the same as the conventional switch shown in the figure.

Since the operation of the switch according to one embodiment of the present invention is similar to the operation of the conventional switch shown in FIGS. 3 and 4, only the differences will be discussed below.

In FIG. 1, a zero normal load current flows in a branched manner through the shape memory alloy α3 and the resistor αη. If the resistance values of the shape memory alloy set 3 and the resistor αη are respectively R1*R2, the combined resistance R is as follows.

If there is no resistor αD, the resistance between the terminals is R1, so
By connecting the resistors αη in parallel, the resistance value is R2>0, so that − is always smaller than 1.

Therefore, the loss of the parallel connection of the shape memory alloy αJ and the resistor αη is reduced to 175 Ω compared to the case where the resistor α is not connected.

Next, we will calculate the temperature rise when a large current is applied. For simplicity, we will first assume that a large current suddenly flows in a non-energized state. Then, it is assumed that one ambient source degree is oc.

When there is no resistor (17+), the heat input Q1 of the shape memory alloy (13) is expressed by the following equation, assuming that the current is 9 energization time it.

Ql = l2R1t X O, 24 (cal) If the mass and specific heat of the shape memory alloy α are m and c, respectively,
The temperature rise θ1 in the shape memory alloy α country is as follows.

Next, when the resistor sides are connected in parallel, the current 2 flowing through the shape memory alloy 0 is as follows.

Therefore, the heat input Q2 of the shape memory alloy αl is as follows.

Further, the temperature rise θ2 at this time is as follows.

C Comparing θ2 and 01, we get the following.

Since R1>0, θ2/θ1 is necessarily smaller than 1.

become that way.

In other words, the temperature rise of the shape memory alloy αj can be suppressed to 1/25.

In this way, by connecting the resistors aη in parallel, -
The loss of the switch can be reduced, and the shape memory alloy a3 can be made difficult to lose its shape memory even when a large current flows. Moreover, since the temperature rise of the shape memory alloy 03 can be suppressed, the shape memory alloy αj can be made difficult to melt.

Another embodiment of the invention is shown in FIG. In this embodiment, a switching semiconductor OQ is connected in parallel to the resistor αD connected in parallel to the shape memory alloy a1. Examples of switching semiconductors include: ■ Zener diode, ■ series connection of two Zener diodes with different Zener breakdown directions, ■ PNPN switching diode, ■ four-layer diode, and ■ diac.

When Zener diodes are connected in parallel, a large current flows and when the voltage between the terminals of the shape memory alloy (13) exceeds the Zener voltage, the current can be shunted to the Zener diode. In the case of alternating current, a series connection of Zener diodes with different Zener breakdown directions may be connected.

PNPN switching element, 4-layer diode.

If one of the diacs is connected in parallel with the shape memory alloy 03, a large current will flow and when the voltage between the terminals of the shape memory alloy 03 exceeds a certain value, these elements will become conductive, so the shape memory The current flowing through Alloy 03 can be shunted to these elements.

In the above embodiments, the case where a shape memory alloy was used as the thermal deformation element α3 was explained.

For example, even when using another thermal deformation element α3 such as a bimetal, the same effects as in the above embodiment can be obtained.

Further, in the above embodiments, the case where the present invention is applied to an electromagnetic contactor has been described, but it is obvious that the present invention can also be applied to other switches such as molded circuit breakers.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a switch in which a contact and a heat deformable element are connected in series, and the contact is opened by deforming the heat deformable element when a large current flows. Equipped with an NFC resistor connected in parallel with the thermal deformable element, it prevents the thermal deformable element from melting and loss of shape memory when a large current is applied, and also prevents the thermal deformable element from melting and losing shape memory. This has the effect of reducing loss during current flow.

[Brief explanation of drawings]

FIG. 1 is a wiring diagram showing the main parts of an embodiment of the present invention, and FIG.
The figure is a wiring diagram showing the main parts of another embodiment of the present invention, FIG. 3 is a partially cutaway front view showing a conventional switch, and FIG. 4 is a wiring diagram showing the main parts of FIG. In the figure, (6A), (6B), (8A)
, (8B) is a contact point. a3 is a shape memory alloy, αe is a contact device, and αD is a resistor. αl is a switching semiconductor. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (4)

[Claims] (1) In a switch in which a contact and a heat deformable element are connected in series and the contact is opened by deforming the heat deformable element when a large current flows, a resistor is connected in parallel with the heat deformable element. A switch characterized by having a body. (2) The switch according to claim 1, wherein the resistor has a switching semiconductor connected in parallel with the resistor. (3) The switching semiconductor is a Zener diode, P
The switch according to claim 2, which is any one of an NPN switching diode, a four-layer diode, and a diac. (4) The switch according to claim 1, wherein the heat deformable element is a shape memory alloy.