JP2009266620A - Bimetal adjustment structure for circuit breaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bimetal adjustment structure for a circuit breaker wherein temperature rise due to abnormal heat generation and deformation of a case do not occur without abnormally generating heat from an electric circuit. <P>SOLUTION: A bimetal piece 8 exists in the electric circuit via a first bendable conductor 14 connected to a chip side and a second bendable conductor 15 connected to a bottom side, a base of the bimetal piece 8 is adhered to a support-plate 17, into which an adjust screw 11 is threaded and supported, via an elastic body 10, the adjust screw 11 is disposed to push the elastic body 10, and a gap G between the bimetal piece 8 and a bargaining piece 9 is adjusted by moving the adjust screw 11 back and forward to the elastic body 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an adjustment structure for adjusting the breaking characteristics of a circuit breaker, and more particularly to a bimetal adjustment structure for a circuit breaker provided with a bimetal piece.

  Circuit breaker tripping methods include a thermal type, a thermal electromagnetic type, a complete electromagnetic type, and an electronic type. Among these, a bimetal piece is used for the thermal type and the thermal electromagnetic type. The tripping mechanism using the bimetal piece uses the bending action caused by the thermal deformation of the bimetal to release the latch and performs the shut-off operation. However, the structure using this bimetal tends to vary in the shut-off operation characteristics. Therefore, it is necessary to adjust the gap (gap) between the bimetal piece and the engaging piece at the manufacturing stage to eliminate the variation. This adjustment is performed using a screw, and a configuration for adjusting the gap by attaching a screw to the engagement piece side (see, for example, Patent Document 1) or a configuration for adjusting the gap by changing the inclination of the bimetal piece by the screw (for example, However, since the configuration in which the gap is adjusted by changing the inclination of the bimetal piece can be configured more compactly, it has been adopted in recent miniaturized circuit breakers.

Japanese Patent Laid-Open No. 7-220607 JP 2000-294110 A

  However, the configuration in which the gap is adjusted by changing the inclination of the bimetal piece is directly on the upper end of the standing part formed by bending the end of the conductor bar disposed on the inner bottom of the breaker case upward. Because the structure is fixed, the adjustment screw is pressed against the upright part, and the adjustment screw is advanced and retracted to adjust the gap, if the adjustment screw is tightened excessively, the conductor bar will not return to its original shape. . Therefore, as a method of solving this problem, a method of forming the upright portion with a leaf spring can be considered, but this method can solve the problem that the upright portion deforms due to excessive tightening of the adjusting screw, but the upright portion is formed. The plate spring is thinner than the conductor bar and the current flow is poor, so the heat generation increases, the temperature rises, the circuit breaker case deforms, and in the worst case, ignition occurs. There is a risk of reaching. In addition, in the conventional configuration, since the support piece for supporting the adjustment screw is formed separately from the bimetal piece, the adjustment is incorrect when the case expands / contracts due to the ambient temperature, and the position of the bimetal piece and the engagement piece also varies. There was a problem that the fluctuation of the gap became large.

  According to the first aspect of the present invention, there are provided a plurality of electric circuits, each of which is provided with a bimetal piece, and a thermal type or thermal electromagnetic type tripping structure is provided. Is a bimetal adjustment structure of a circuit breaker in which a gap between the engagement piece and the engagement piece that is engaged by the occurrence of an overcurrent can be adjusted by an adjustment screw, and the bimetal piece is connected to the distal end side of the first flexible conducting wire and the proximal end side The second flexible conductive wire connected to the cable is interposed in the electric circuit, the base of the bimetal piece is fixed to the elastic body, the adjustment screw is pressed against the elastic body, and the adjustment screw is advanced and retracted relative to the elastic body. This is characterized in that the gap is adjusted.

  According to a second aspect of the present invention, in the bimetal adjusting structure for a circuit breaker according to the first aspect, the bimetal piece is fixed to the support plate for screwing and supporting the adjusting screw through the elastic body. To do.

  According to the first aspect of the present invention, since no current flows through the elastic body that supports the bimetal piece, the electric circuit does not generate heat abnormally, and there is an effect that temperature rise due to abnormal heat generation, deformation of the case, and the like do not occur. is there.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, since the support plate supporting the bimetal piece and the adjusting screw is integrally formed, the case expands / contracts depending on the ambient temperature. However, adjustment does not go out of the way, and there is an effect that fluctuation of the gap due to expansion / contraction of the case can be reduced.

  A circuit breaker bimetal adjustment structure according to the present invention will be described with reference to FIGS.

  FIG. 1 is a longitudinal sectional view of a thermal electromagnetic circuit breaker having a bimetal adjustment structure according to the present invention, where 1 is a power supply side terminal, 2 is a load side terminal, and 3 is an operation handle for opening and closing an electric circuit. Reference numeral 4 denotes an opening / closing contact portion composed of a movable contact 5 and a fixed contact 6, and 7 an opening / closing mechanism for opening / closing the opening / closing contact portion 4 in response to the operation of the operation handle 3 and for interrupting the electric circuit in response to detection of an abnormal current. , 8 is a bimetal piece for detecting overcurrent, 9 is an engagement piece for interrupting the opening / closing mechanism 7 by the engagement operation of the bimetal piece 8, 10 is an elastic body for supporting the bimetal piece 8, and 11 is bimetal. An adjusting screw for adjusting the gap (gap G) between the piece 8 and the engaging piece 9, 12 is an electromagnetic tripping element having a movable iron piece 12a for detecting a short-circuit current, and 13 is a circuit breaker case (hereinafter simply referred to as a case). ).

  This circuit breaker is a two-pole circuit breaker having two electric circuits, and the power supply side terminal 1, the load side terminal 2, the switching contact portion 4 and the bimetal piece 8 are all provided in pairs. ing. The following description will be made with the right side of the drawing provided with the load side terminal 2 as the front, the left side of the drawing provided with the power supply side terminal 1 as the rear, and the operation handle 3 mounting portion as the upper part.

  The movable contact 5 and the fixed contact 6 are arranged in the vertical direction, and contacts (movable contact 5a, fixed contact 6a) are provided in the upper part. The movable contact 5 is installed so that the upper part can swing back and forth with the lower end as a fulcrum, and is connected to the bimetal piece 8 by a first flexible conductive wire 14. On the other hand, the fixed contact 6 is formed integrally with the terminal fitting of the power supply side terminal 1 and is fixed in the case 13. Then, the movable contact 5 moves back and forth in response to the opening / closing operation of the opening / closing mechanism section 7, contacts / releases between the movable contact 5 a and the fixed contact 6 a, and energizes / cuts off the electric circuit.

  The bimetal piece 8 is disposed in the front-rear direction, the rear base end portion is supported via the elastic body 10 on the support plate 17 into which the adjusting screw 11 is screwed and supported, and the free end is disposed obliquely upward. Has been. The first flexible conductive wire 14 is welded to the intermediate portion on the distal end side of the bimetal piece 8, and one end of the second flexible conductive wire 15 is welded to the intermediate portion on the proximal end side of the bimetal piece 9. The other end is welded to a conductor bar 16 extending from the terminal fitting of the load side terminal 2 so that the bimetal piece 8 constitutes a part of the electric circuit. On the other hand, the engagement piece 9 with which the bimetal piece 8 is engaged includes a first engagement portion 9a with which the bimetal piece 8 contacts and a second engagement portion 9b with which the electromagnetic tripping element 12 contacts.

  The adjustment screw 11 is disposed on the lower side of the power supply side terminal 1 so as to face forward, is screwed and supported in the screw hole 17a of the support plate 17 assembled in the case 13, and the adjustment screw 11 itself is also embedded in the case 13. It is assembled as follows. The support plate 17 is formed in a substantially L shape with a horizontal portion 17c extending forward from the lower end of the vertical portion 17b in which the screw hole 17a is formed, and the elastic body 10 is welded to the horizontal portion 17c.

  The elastic body 10 is formed by bending both ends of the leaf spring in opposite directions, an intermediate portion is disposed in parallel with the vertical portion 17b of the support plate 17, a lower end portion is welded to the horizontal portion 17c, and an upper end portion is formed. The bimetal piece 8 is welded. On the back surface of the case 13, an operation hole 18 for rotating the adjustment screw 11 to advance and retreat is provided, and the tip of the adjustment screw 11 is configured to abut against an intermediate portion of the elastic body 10.

  When the adjustment screw 11 is screwed in, the elastic body 10 is pressed forward. Since the upper portion of the elastic body 10 thus pressed tilts forward, the bimetal piece 8 attached to the upper end of the elastic body 10 tilts in conjunction with it. As a result, the tip extending forward is tilted downward, and the gap G between the engagement piece 9 is reduced.

  The circuit breaker configured as described above operates as follows. When the operation handle 3 is rotated backward from the off state shown in FIG. 1 and turned on, the opening / closing mechanism unit 7 operates the movable contact 5 to contact the fixed contact 6, and the circuit breaker is turned on. . This state is maintained by the action of the latch mechanism in the opening / closing mechanism section 7, and when an abnormal current flows in the electric circuit, the latch is released and the opening / closing mechanism section 7 performs a blocking operation. Among these abnormal currents, the overcurrent is detected by deformation (curving) of the bimetal piece 8, and when it is deformed and abuts on the first engagement portion 9a of the engagement piece 9, the engagement piece 9 rotates, The latch is released and the operation is interrupted. Further, for the short-circuit current, the electromagnetic tripping element 12 operates, the movable iron piece 12a is engaged with the second engagement portion 9b of the engagement piece 9, and the latch is released and shut off in the same manner as in the case of overcurrent occurrence. Operate.

  As described above, the bimetal piece 8 is provided on the support plate 17 through which the adjustment screw 11 is screwed and supported via the elastic body 10, and the adjustment screw 11 is advanced and retracted to the elastic body 10 to adjust the gap G. Since the bimetal piece 8 and the electric circuit are connected by the flexible conductive wires 14 and 15 so that no current flows, the elastic body 10 does not generate heat abnormally, and problems such as temperature rise and case deformation do not occur. Further, since the support plate for supporting the bimetal piece 8 and the adjusting screw 11 is integrally formed, even if the case 13 expands / contracts due to the ambient temperature, the adjustment does not go wrong, and the fluctuation of the gap due to the expansion / contraction of the case 13 is reduced. be able to.

  Although the adjustment screw 11 is adjusted from the back of the case 13, the adjustment screw 11 may be arranged upward to press the base end of the horizontal bimetal piece 8 upward. In this case, the operation hole 18 is provided at the bottom of the case 13.

It is a section explanatory view of a circuit breaker which shows an example of a bimetal adjustment structure concerning the present invention. It is explanatory drawing which extracted the bimetal piece of FIG. 1, the adjustment structure part, and the electrical circuit.

Explanation of symbols

8 Bimetal piece 9 Engagement piece 10 Elastic body 11 Adjustment screw 13 Circuit breaker case 14 First flexible conductor 15 Second flexible conductor 16 Conductor bar 17 Support plate

Claims (2)

  A gap between a plurality of electric paths, bimetal pieces provided in each electric circuit, and a thermal or thermal electromagnetic tripping structure, the bimetal pieces engaging with each other upon occurrence of overcurrent A circuit breaker bimetal adjustment structure that can be adjusted by an adjustment screw, wherein the bimetal piece is connected to the electric circuit by a first flexible conductor connected to the distal end and a second flexible conductor connected to the proximal end. The gap is adjusted by interposing, fixing the base of the bimetal piece to an elastic body, pressing the adjustment screw against the elastic body, and moving the adjustment screw forward and backward with respect to the elastic body. Bimetal adjustment structure of circuit breaker characterized by that.   The bimetal adjustment structure for a circuit breaker according to claim 1, wherein the bimetal piece is fixed to a support plate into which the adjustment screw is screwed in via the elastic body.

Images