JP2002237249A - Thermal overload relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a reverse action by fixing the abutting point of a helical tension spring against a release lever, in a thermal overload relay to switch a contact by reversing a reverse plate by pushing the helical tension spring by the release lever. SOLUTION: The coil part 12b of the helical tension spring 12 to reverse the reverse plate 11 by being pushed by the release lever 7 is formed like an abacus bead shaped counter having a swelled part in the middle, and the release lever 7 is made to abut on the swelled part. If a control dial 16 is rotated, an adjusting link 14 rotates, and the position of the release lever 7 rotatably supported by the adjusting link 14 moves in order to adjust an operating current. However, since the abutting point of the helical tension spring 12 against the release lever 7 is fixed, lateral rigidity of the helical tension spring 12 is kept constant, in order to make sure of a snap-action when reversing the reversing plate 11.

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 utilizing a bending characteristic caused by a rise in temperature of a bimetal, and more particularly to an improvement of a reversing mechanism which operates by receiving a displacement of the bimetal.

[0002]

2. Description of the Related Art FIG. 6 is a front view showing the inside of an operation section of a conventional thermal overload relay. In FIG. 6, the thermal overload relay includes a heating section that bends and displaces the bimetal 1 due to heat generated by an energizing current, and when the amount of displacement of the bimetal 1 exceeds a specified value, inverts the inverting mechanism 2 so that the contact 3 And an operation unit 5 for switching between. The configuration and operation will be described below. When the bimetal 1 is curved, its upper end is displaced rightward in FIG. This movement is transmitted to the release lever 7 via the shifter 6, and the release lever 7 rotates counterclockwise about the shaft 8 as a fulcrum. On the other hand, V at one end of the support frame 10 fixed to the case 9
A reversing plate 11 is abutted against the groove 10 a so that one end of the reversing plate 11 is turned around, and a tension coil spring 12 is hung between the other end and the other end of the support frame 10. A movable plate 13 is fixed to the reversing plate 11.

[0003] In the initial state of FIG.
Acts to rotate the reversing plate 11 clockwise about one end, and the reversing plate 11 is stopped in the illustrated state. Release lever 7 due to bending displacement of bimetal 1
When the release lever 7 rotates counterclockwise, the release lever 7 pushes the linear portion 12a of the tension coil spring 12 with the semicircular projection 7a,
The tension coil spring 12 is rotated counterclockwise. Along with this, the reversing plate 11 also rotates counterclockwise. In this case, when the amount of displacement of the bimetal 1 exceeds the specified value and the amount of rotation of the release lever 7 increases accordingly, the action of the tension coil spring 12 on the reversing plate 11 overcomes the dead point where the action changes from clockwise to counterclockwise. . When the dead center is exceeded, the reversing plate 11 rapidly reverses counterclockwise.

On the other hand, the fixed contact 3a of the normally closed contact 3 is attached to the tip of a fixed contact spring cantilevered by the case 9 near the release lever 7, and comes into contact with the fixed contact 3a in the initial state of FIG. As described above, the movable contact 3b is attached to the reversing plate 11. The fixed contact 4a of the normally open contact 4 is attached to the tip of a fixed contact spring that is cantilevered near the upper surface of the case 9, and the tip of the movable contact spring that is cantilevered substantially in parallel with the fixed contact spring is The movable contact 4b is attached so as to face the fixed contact 4a. Therefore,
When the reversing plate 11 is reversed as described above, the normally closed contact 3 is opened, and the normally closed contact 4 is closed by the movable contact spring being pushed by the rod-shaped projection 13a of the movable plate 13 (trip). The release lever 7, the reversing plate 11, the tension coil spring 12, and the like constitute the reversing mechanism 2.

Here, the release lever 7 is rotatably connected to the adjustment link 14 by a shaft 8. One end of the adjustment link 14 is formed by a leaf spring 15,
a, and the other end is pressed against the cam surface of the adjustment dial 16 rotatably held by the case 9. Therefore, when the adjustment dial 16 is turned counterclockwise, the radius of rotation of the cam surface decreases, and the adjustment link 14 moves rightward to the position indicated by the broken line. Along with this, the release lever 7 connected to the adjustment link 14 is displaced to the position indicated by the broken line. As a result, the gap between the shifter 6 and the release lever 7 increases, and the operating current value (current value at which the reversing mechanism 2 performs the reversing operation) increases. Turning the adjustment dial 16 clockwise decreases the operating current value.

[0006]

The above-mentioned reversing mechanism 2
When the release lever 7 pushes the tension coil spring 12, the reversing plate 11 does not gradually rotate, but only the tension coil spring 12 bends and deforms until just before the dead center is exceeded. Upon arrival, the reversing plate 11 is configured to perform a so-called snap operation in which the reversing plate 11 is reversed at a stroke. On the other hand, when the release lever 7 moves from the solid line position to the broken line position due to the adjustment of the operating current value, the contact point of the release lever 7 with the tension coil spring 12 (the position of the projection 7a) also moves by C. However, when the contact point 7a moves away from the coil portion 12a of the tension coil spring 12 as shown in the drawing, the apparent lateral rigidity of the tension coil spring 12 increases, and as a result, the release lever 7 pushes the tension coil spring 12. In such a case, the reversing plate 11 cannot be reversed at a stretch, but is gradually rotated while being reversed, so that there is a problem that the snap operation becomes uncertain. Therefore, an object of the present invention is to provide a stable snap operation of the reversing mechanism regardless of the position of the release lever.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a heating unit for bending and displacing a bimetal by the heat generated by a supplied current, and a reversing mechanism when the displacement of the bimetal exceeds a specified value. An operation unit for operating and switching a contact, wherein the reversing mechanism is a release lever rotatably connected to an adjustment link interlocked with an operation current adjustment dial, a reversing plate for reversing one end about a fulcrum, A tension coil spring acting on the other end of the plate, wherein the release lever pivots in response to the displacement of the bimetal, and pushes the tension coil spring from the side, thereby acting on the reversing plate of the tension coil spring. When the reversal is performed, in the thermal overload relay in which the reversing plate is reversed and the contacts are switched, the coil portion of the tension coil spring is formed into an abacus ball shape in which the middle part bulges. Turn, is intended to push the bulged portion in the release lever (claim 1). According to the first aspect, since the release lever always contacts the bulging portion of the tension coil spring even when the position changes, the lateral rigidity of the tension coil spring does not change by adjusting the operating current value. If a guide groove for receiving the bulging portion of the tension coil spring is formed in the contact portion of the release lever with the tension coil spring, the contact between the release lever and the tension coil spring is stabilized (claim 2).

[0008]

FIG. 1 is a front view showing the inside of an operation section of a thermal overload relay according to an embodiment of the present invention.
FIG. 2 is a perspective view of the tension coil spring in FIG. 1, and FIG. 3 is a perspective view of the release lever similarly. First, in FIG. 2, the tension coil spring 12 has a coil portion 12b wound in the form of an abacus ball with a bulging middle as shown. As shown in FIG. 1, the tension coil spring 12 is hung between the reversing plate 11 and the support frame 10 via the hooks at the ends of the straight portions at both ends, as shown in FIG. In 2), the contact plate 7b of the release lever 7 shown in FIG. 3 is in contact. In such a thermal overload relay, even if the release lever 7 moves from the solid line position to the broken line position by adjusting the operating current value, the contact plate 7b always comes into contact with the bulging portion 12c. Therefore, the lateral rigidity of the tension coil spring 12 is also unchanged, and the reversing operation of the reversing mechanism 2 is performed by a stable snap operation at the time of trip.

FIG. 4 is a perspective view of a main part of the release lever 7 showing an embodiment in which an arc groove 7c is formed in the contact plate 7b of the release lever 7 along the longitudinal direction of the tension coil spring 12, and FIG. It is a principal part perspective view in which the groove 7d was formed. Contact plate 7
An arcuate groove 7c or a V-shaped groove 7d is formed in the groove, and the bulge 12c is received by the groove 7c.
Sliding upward, the contact between the release lever 7 and the tension coil spring 12 is further stabilized.

[0010]

As described above, according to the present invention, the tension coil spring of the reversing mechanism is wound in the form of an abacus ball with a bulging middle part, and the bulging part is pushed by the release lever, whereby the operation is achieved. A stable inversion operation is always performed regardless of the current value, and a stable contact switching signal can be obtained.
Further, the present invention can be implemented at low cost and easily because only the shape of the coil portion of the tension coil spring is changed.

[Brief description of the drawings]

FIG. 1 is a front view of an operation unit of a thermal overload relay according to an embodiment of the present invention.

FIG. 2 is a perspective view of a tension coil spring in FIG.

FIG. 3 is a perspective view of a release lever in FIG. 1;

FIG. 4 is a main part perspective view showing a different embodiment of the release lever of FIG. 3;

FIG. 5 is a main part perspective view showing still another embodiment of the release lever of FIG. 3;

FIG. 6 is a front view of an operation unit of a thermal overload relay showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bimetal 2 Inversion mechanism 3 Contact 4 Contact 5 Operation part 6 Shifter 7 Release lever 7b Contact plate 7c Arc groove 7d V groove 9 Case 11 Inversion plate 12 Tension coil spring 12b Coil part 12c Swelling part 14 Adjustment link 16 Adjustment dial

Claims (2)

[Claims] 1. A heating unit for bending and displacing a bimetal due to heat generated by an energizing current, and an operation unit for switching a contact by operating a reversing mechanism when the amount of displacement of the bimetal exceeds a specified value. A release lever rotatably connected to an adjustment link interlocked with an operating current adjustment dial, a reversing plate for reversing one end with a fulcrum, and a tension coil spring acting on the other end of the reversing plate; When the lever rotates in response to the displacement of the bimetal and pushes the tension coil spring from the side, and the action of the tension coil spring on the reversing plate is reversed, the reversing plate is reversed and the thermal contact is switched. In the overload relay of the type, the coil portion of the tension coil spring is wound in the form of an abacus ball with a bulging middle, and the bulging portion is pushed by the release lever. Thermal overload relay. 2. A thermal overload relay according to claim 1, wherein a guide groove for receiving said bulging portion is formed in a contact portion of said release lever with said tension coil spring.