JP2000260289A - Thermal overload relay - Google Patents

Abstract

(57) [Problem] To provide a sufficient contact gap between fixed and movable contacts by compensating for dimensional tolerances when a normally closed contact is opened by manual operation of an opening button. . A reversing mechanism (2) that is driven by the displacement of a main bimetal, a normally closed contact (3) that opens when the mechanism is reversed, and an opening button (8) that opens the normally closed contact by manual operation are provided. The movable contact 3a of the closed contact is mounted on the oscillating movable plate 2b of the reversing operation mechanism, and the fixed contact 3b is mounted on the contact support piece 9 of a leaf spring. In a thermal overload relay in which a contact is opened, when a normally closed contact is opened by a button operation, an opening button is used as an opening assisting means for simultaneously separating the fixed contact and the movable contact of the normally closed contact. Tapered cam section 8
When the release button is pressed, the tapered cam portion is pressed against the corner portion 2d-1 of the L-shaped lever 2d to displace the movable plate of the reversing mechanism in the contact release direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal overload relay (thermal relay) used in combination with an electromagnetic contactor.

[0002]

2. Description of the Related Art As a measure for overload protection of a motor or the like, a thermal contact type overload relay is combined with an electromagnetic contactor connected to its power supply circuit, and during overload operation, the current is cut off by the electromagnetic contactor and the motor is stopped. Such a method is generally adopted as a standard power distribution method.

[0003] Various types of thermal overload relays are known. As described below, a normally-closed contact release button is built in and a sequence of an electromagnetic contactor is performed in a no-load state. When performing a check, etc., the normally closed contact is turned off by manual button operation, thereby opening the electromagnetic coil of the electromagnetic contactor and tripping the electromagnetic contactor. Load relays are known.

Next, a typical conventional structure of the thermal overload relay having a built-in release button is shown in FIGS.
This is shown in (b). In the figure, 1 is a case of a thermal overload relay, 2 is a reversing mechanism for opening and closing contacts, 3 is a normally closed contact,
4 is a normally open contact, 5 is a release lever connecting the shifter 6a of the main bimetal 6 and the reversing mechanism 2, 7 is a reset button provided on the upper surface side of the case 1, and 8 is a normally closed contact 3.
Is a release button for manually releasing.

Here, the reversing operation mechanism 2 has a swingable movable plate 2b having one end locked and supported by a V groove of a support arm 2a.
A reversing drive spring (tension coil spring) 2c stretched between the tip of the movable plate 2b and the case; and a drive for normally-open contacts made of an insulator protruding backward from the movable plate 2b in an L-shape. The movable contact 3a of the normally closed contact 3 is attached to the tip of the movable plate 2b. The fixed contact 3b of the normally closed contact 3 is attached to a contact support piece 9 having a leaf spring structure, one end of which is fixed to the bottom of the case 1 and laid horizontally. Reference numeral 1a denotes a protruding stopper provided on the case 1 so as to face the intermediate point of the contact support piece 9.

On the other hand, the release button 8 is incorporated in the case 1 with the tip (lower end) of the rod 8a facing the contact support piece 9 of the fixed contact 3a of the normally closed contact 3 described above. No return spring is urged toward the illustrated standby position.

[0007] With this configuration, during normal operation, the movable plate 2 b of the reversing drive mechanism 2 receives the spring force of the reversing drive spring 2 c and tilts clockwise from the neutral position, as shown in the figure, and the normally closed contact 3
The movable contact 3a (which is connected in series with the electromagnetic coil of the electromagnetic contactor) is pressed against the fixed contact 3b to keep the contact ON. In this state, the normally open contact 4 is
FF.

Here, when an overload current flows in the main circuit, the main bimetal 6 is heated and bent, and the release lever 5 is pushed rightward through the shifter 6a. As a result, the release lever 5 swings counterclockwise about the fulcrum 5a to push up the intermediate point of the reversing drive spring 2c of the reversing operation mechanism 2 upward,
When the displacement of the spring exceeds the dead center of the movable plate 2b, the movable contact 3a of the normally closed contact 3 is quickly separated in a clockwise direction, and the movable contact 3a of the normally closed contact 3 is separated from the fixed contact 3b. The contact piece is pushed to switch its contact ON.

On the other hand, in order to perform a sequence check of the electromagnetic contactor, when the release button 8 is manually pressed from the outside with no load, the rod of the release button 8 is pushed as shown in FIG. The tip contacts the contact support piece 9 and pushes the tip downward. Therefore, the contact support piece 9 is bent downward with the stopper 1a as a fulcrum, and the fixed contact 3 of the normally closed contact 3 is bent.
b is retracted in the direction in which it is separated from the movable contact 3a. In addition, at the same time, the reversing operation mechanism 2 is a corner portion of the L-shaped lever 2d made of an insulating material (inclined at a bent corner portion).
2d-1 abuts against the stopper 1b on the case 1 side and stops at the illustrated position. As a result, the normally closed contact 3 is opened, and the electromagnetic coil of the electromagnetic contactor combined with the thermal overload relay is turned off and trips.

[0010]

In the above-described conventional normally-closed contact opening mechanism, the opening button 8 is provided as follows.
The operation when the normally closed contact 3 is opened by the above operation becomes unstable. That is, in the conventional structure, the release button 8
, The contact supporting piece 9 is pushed down to separate the fixed contact 3b of the normally closed contact 3 from the movable contact 3a. In addition, in consideration of the stress limit of the leaf spring material of the contact support piece 9 in terms of design, the depression stroke of the contact support piece 9 is set to only about several mm.
The contact gap between the movable contact 3a and the fixed contact 3b fluctuates in a state after the contact is opened due to dimensional tolerances of the assembly, and the normally closed contact 3 is sufficiently opened even if the opening button 8 is pressed based on this. In some cases, such as an operational defect.

Although it is possible to adopt a leaf spring material having a high stress limit as the contact support piece 9 and design it to have a large opening stroke, a leaf spring material having a high stress limit can be used. Is expensive and the cost of the product is high. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to compensate for dimensional tolerances of parts and assemblies when a normally-closed contact is opened by manual button operation, and to provide a gap between a fixed contact and a movable contact. Another object of the present invention is to provide a thermal overload relay with a built-in release button in which a contact release mechanism is improved so that a stable contact gap can be secured.

[0012]

According to the present invention, there is provided, in accordance with the present invention, a reversing mechanism driven by a release lever driven by a displacement of a main bimetal, and a normally closed mechanism which is opened and closed by reversing the mechanism. A thermal overload relay equipped with a contact, a normally-open contact, and an opening button for manually opening the normally-closed contact from outside, wherein the movable contact of the normally-closed contact is swung by a reversing operation mechanism. The fixed contact is attached to the contact support piece of the leaf spring on the movable plate, and the tip of the release button is arranged to face the contact support piece, and the contact support piece is displaced backward by pushing the release button and normally closed. In the one in which the contacts are opened, during the opening operation of the normally closed contact by manual operation, the normally closed contact that retreats the movable plate of the reversing operation mechanism from the steady position in conjunction with the pressing of the opening button. Separation aid Kicking and (claim 1) ones, specifically constituting the separable assisting means as follows follow.

[0013] That is, as the separation assisting means in the above configuration, a taper cam portion projecting laterally from an intermediate portion between the separation button and the tip thereof is provided on the separation button, and the taper cam portion is moved by the movable piece of the reversing mechanism. The movable plate of the reversing operation mechanism is separated from the normally closed contact by pressing the tapered cam portion against the corner of the lever when the release button is pressed in such a manner that the movable plate faces the corner of the normally open contact drive lever connected to the lever. It is made to retreat in the direction (claim 2).

In the above construction, when the release button is pushed in, the tip of the rod pushes the contact supporting piece supporting the fixed contact of the normally closed contact to retreat in the opening direction, and at the same time, is provided at the intermediate portion of the rod. The tapered cam portion displaces the movable piece of the reversing operation mechanism, which is the follower, in the direction in which the movable contact of the normally closed contact is separated from the fixed contact. That is, when the release button is pressed, the fixed contact of the normally closed contact and the movable contact are simultaneously separated in the opening direction. As a result, even if the pushing stroke of the contact support piece made of a leaf spring material is set small, the parts and
A sufficient contact gap between the fixed contact and the movable contact can be ensured by compensating for the variation caused by the dimensional tolerance of the assembly.

[0015]

FIG. 1 is a block diagram showing an embodiment of the present invention.
A description will be given based on the embodiment. In the drawings of the embodiment, the same members corresponding to FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted. That is, only the normally closed contact opening mechanism is shown in FIG. 1, but the other structure is the same as that of the conventional thermal overload relay shown in FIG. 2 (a). here,
The difference from the structure shown in FIG. 2 is that an intermediate portion between the rod 8a of the release button 8 and the distal end thereof has a reversing operation mechanism 2.
A triangular tapered cam portion 8b also serving as a stopper is protruded from the movable plate 2b of the reversing operation mechanism 2 behind the corner 2d-1 of an L-shaped lever (drive lever for normally open contact) 2d made of an insulator. It is formed so as to protrude toward the side. The cam surface of the tapered cam portion 8b has an acute angle with a small taper angle, and at the standby position of the release button 8, separates from the lever 2d of the reversing mechanism 2 and moves back to an upper position as indicated by a dotted line. When the release button 8 is manually depressed, the lever 2d is lowered to the actual gland position so as to press the corner 2d-1 of the lever 2d.

In this configuration, when the release button 8 is pushed from the dotted line position to the solid line position, the tip of the rod 8a abuts against the contact support piece 9, and the fixed contact 3b is pushed down from the dotted line position to the solid line position to make the normally closed contact. The third fixed contact 3b is separated from the movable contact 3a. Simultaneously with this movement, the tapered cam portion 8b descends from above and the reversing mechanism 2
Of the L-shaped lever 2d (the corner is inclined or formed in an arc-shaped surface), and the lever 2d is pushed laterally along the cam surface of the tapered cam portion 8b. By this cam operation, the oscillating movable plate 2b of the reversing operation mechanism 2
, A counterclockwise moment about the V-groove of the support arm 2a is applied, and the moment is slightly displaced from the dotted line position to the solid line position in the drawing, and the movable contact 3a of the normally closed contact 3 attached to the movable plate 2b
Is pulled away from the fixed contact 3b. In this state, since the reversing drive spring 2c shown in FIG. 2 is at the steady position, the reversing operation mechanism 2 does not perform the reversing operation.
As a result, in the state after the normally closed contact 3 is opened, the movable contact 3a
And a sufficient contact gap between the fixed contact 3b.

[0017]

As described above, according to the structure of the present invention, the taper cam portion is added to the release button, and the fixed contact of the normally closed contact and the movable contact are simultaneously released by pressing the button. By separating in the direction, even if the pushing stroke of the contact support piece made of leaf spring material is set small, it compensates for the variation caused by the dimensional tolerance of parts and assembly after the contact is opened. A sufficient contact gap can be secured between the fixed contact and the movable contact,
Thereby, the reliability of the opening operation of the normally closed contact by manual operation is improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the configuration and operation of a normally closed contact opening mechanism of a thermal overload relay according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional thermal overload relay;
(a) is an internal mechanism diagram, (b) is a diagram showing the opening operation of the normally closed contact when the release button is pushed in

[Explanation of symbols]

 2 Reversing operation mechanism 2b Oscillating movable plate 2c Reversing drive spring 2d Normally open contact drive lever 2d-1 corner 3 Normally closed contact 3a Movable contact 3b Fixed contact 4 Normally open contact 5 Release lever 6 Main bimetal 8 Release button 8a Rod 8b Tapered cam 9 Contact support piece (leaf spring)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Fumihiro Morishita 1-1 1-1 Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside Fuji Electric Co., Ltd. No. 1 Fuji Electric Co., Ltd.

Claims (2)

[Claims] 1. A reversing operation mechanism driven by a release lever driven by a displacement of a main bimetal, a normally closed contact opened and closed by the reversing operation of the mechanism, a normally open contact, and the normally closed contact by manual operation from outside. A thermal overload relay equipped with an opening button for opening and closing, the movable contact of the normally closed contact is mounted on a swingable movable plate of a reversing operation mechanism, and the fixed contact is mounted on a contact support piece of a leaf spring. The tip of the release button is disposed opposite to the contact support piece, and the contact support piece is displaced backward by pushing the release button to open the normally closed contact. A thermally actuated overload, characterized in that there is provided a normally-closed contact opening assisting means for retracting the movable plate of the reversing operation mechanism from the steady position in conjunction with the pushing of the opening button during the opening operation of the opening operation. relay. 2. The thermal overload relay according to claim 1, further comprising a taper cam portion protruding laterally from an intermediate portion between the release button and the tip of the release button as the release assisting means. The tapered cam portion is opposed to the corner portion of the normally open contact drive lever connected to the movable plate of the reversing operation mechanism, and when the release button is pressed, the tapered cam portion is pressed against the corner portion of the lever to operate the reversing operation mechanism. A thermal overload relay characterized in that a movable plate is displaced backward in a direction of opening a normally closed contact.