JP2006073405A - Heat element for thermal relay - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure stable curvature operating characteristic, to reduce consumed power and to reduce heat interference between phases by uniformly winding heater wire to bimetal without any deviation in winding pitch by applying a simple processing to the bimetal. <P>SOLUTION: A heat element corresponds to each phase of the main circuit of a thermal relay which is linked to each contact point mechanism through a shifter. The heat element 2 consists of the bimetal 6 with an operating end confronting the shifter and connected to the main circuit by having another end fixed to a terminal 10, and the heater wire 8 which is serially connected with the bimetal by being wound around the periphery surface of the bimetal. Indented grooves 6b for alignment retaining the heater wire 8 to a specified winding position are formed on the right and left side edges of the bimetal according to the winding pitch p of the heater wire. Furthermore, the periphery surfaces of the bimetal and the heater wire are covered by a heat resistant thermal insulator 11 in an assembled state with the heater wire wound to the bimetal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a structure of a heat element of a thermal relay that performs overcurrent and phase loss protection of a load (for example, an electric motor) in combination with a circuit breaker for wiring, an electromagnetic contactor, and the like.

First, the conventional structure of the thermal relay described above is shown in FIGS. 3 and 4 (see, for example, Patent Document 1). In FIG. 3, reference numeral 1 denotes a mold case. In the case 1, the main circuit U.S. V. W heat element 2 corresponding to each phase of heat element 2, shifter 3 slidably arranged linked to the distal end side operation end of heat element 2 of each phase, contact point arranged on top of the shifter 3 and the case A thermal relay is configured by incorporating a reversing spring mechanism 5 that links the mechanism 4 and opens and closes the contact of the contact mechanism 4 in response to the displacement of the shifter 3.
Here, as shown in FIG. 4A, the heat element 2 is mainly formed by winding the heater wire 8 around the outer periphery of the bimetal 6 in a coil shape and connecting the bimetal 6 and the heater wire 8 directly. This is a direct-heat-type heat-responsive element in which circuit current is passed and the bimetal 6 is bent and displaced by heat generation. Specifically, the peripheral surface of the strip-shaped bimetal 6 (see FIG. 4B) The heater wire 8 is uniformly wound at a predetermined pitch p on the insulating tape 7 wound around the wire, and the upper end 8a (winding start end) of the heater wire 8 is connected to the power source side terminal 9 and the other end (winding end). The end 8b is joined to the plate surface of the bimetal 6. Further, the upper end of the bimetal 6 is coupled to the load side terminal 10, and the operation end 6a on the lower end side is opposed to the shifter 3 described above.

The operation of the thermal relay having the above configuration is well known. When an overload current flows in the main circuit, the bimetal itself is bent by the heat generated by the heater wire 8 and the bimetal 6, and the operation end 6a is displaced to shift the shifter. 3 is pressed, thereby switching the contact of the contact mechanism 4 through the reversing spring mechanism 5. In the thermal relay incorporated in the circuit breaker for wiring, the displacement of the shifter 6 described above is transmitted to the latch mechanism of the contact opening / closing mechanism so that the main circuit contact is tripped.
Japanese Patent Laid-Open No. 4-67525

By the way, the above-described conventional heat element has the following problems in terms of production and quality control.
That is, in order to wind the heater wire 8 around the bimetal 6, the winding start of the heater wire 8 fed out from the bobbin is fixed to the bimetal 6 set in the winding jig, the bimetal is rotated, and the heater wire is Winding around the circumference of the bimetal while applying tension and a predetermined pitch feed is performed, but the winding of the heater wire 8 as shown in FIG. When the position is partially deviated from the fixed position, and the winding pitch is displaced at the position of the heater wire 8 thus deviated as p ', the heat distribution of the heater wire 8 and the mechanical action of the bimetal 6 due to the winding of the heater wire As a result, the amount of bending displacement of the bimetal 6 varies and the operating characteristics of the thermal relay change. In addition, in the conventional structure, since the shape of the bimetal 6 is straight as shown in FIG. 4B, the above-described deviation of the winding pitch tends to occur when the heater wire 8 is wound.

Therefore, in the past, a characteristic test was performed for each manufactured heat element to check the bending displacement characteristics of the bimetal, and the bimetal bending amount was adjusted as necessary to correct the characteristics. It takes time and increases the product cost.
In addition to the above problem, in the heat element having the conventional structure, the heater wire 8 wound around the bimetal 6 is exposed to the air as it is, so that part of the heat generated by the heater wire does not transfer to the bimetal 6. There is a problem in that heat is dissipated into the air, and the amount of power consumed to obtain a desired bimetal bending displacement amount due to the heat loss resulting in heat loss. Furthermore, as shown in FIG. 3, the heat relay assembly structure in which U, V, W heat elements 2 are arranged side by side inside the case 1. The amount of bending displacement of the bimetal 6 changes between the V-phase heat element arranged in the center due to thermal interference between the heat element phases and the U- and W-phase heat elements arranged on both sides of the heat element. Therefore, in actual products, it is necessary to design the bimetal and adjust the curvature of each phase in consideration of thermal interference between phases.

  The present invention has been made in view of the above points, and by performing simple processing on the bimetal beforehand, the heater wire is evenly wound around the bimetal without any deviation in winding pitch, and stable bending operation characteristics. It is an object of the present invention to provide a heat element for a thermal relay whose structure is improved so that power consumption can be reduced and thermal interference between phases can be reduced.

In order to achieve the above object, according to the present invention, there is provided a heat element corresponding to each phase of a main circuit of a thermal relay linked to a contact mechanism through a shifter, and the heat element is operated on the shifter. In what consists of a bimetal connected to the main circuit by fixing the other end to the terminal and connected to the main circuit, and a heater wire wound around the peripheral surface of the bimetal and connected in series to the bimetal,
A concave groove for positioning that holds the heater wire at a predetermined winding position is formed in the bimetal in accordance with the winding pitch of the heater wire (Claim 1), and specifically in the following manner. Constitute.
(1) In the heat element having the above-described configuration, the concave grooves are formed on the left and right side edges of the bimetal.
(2) In the heat element having the above-described configuration, concave grooves are formed on both front and back surfaces of the bimetal.
(3) Further, in addition to the concave groove, the bimetal and the surface of the heater wire are covered with a heat-resistant heat insulating material in an assembled state in which the heater wire is wound around the bimetal.

According to said structure, there exists the following effect. In other words, positioning grooves for holding the heater wire at a predetermined winding position in accordance with the winding pitch of the heater wire are formed on the left and right side edges or front and back surfaces of the bimetal so that the heater wire is formed on the bimetal. In the process of winding the heater wire, it is possible to wind and hold the heater wire evenly at a constant pitch without any deviation in the winding pitch by wrapping the heater wire in the concave groove. Stable heat element can be manufactured.
In addition to the above-mentioned concave groove, in the assembled state in which the heater wire is wound around the bimetal, the bimetal and the heater wire are covered with a heat-resistant heat insulating material, so that heat radiation to the surroundings is reduced, and the heater wire accompanying energization Can be efficiently transferred to the bimetal to save power consumption, and the winding position of the heater wire can be prevented from shifting due to handling after assembly. Further, since heat radiation from the heat element of each phase to the surroundings is reduced, it is possible to prevent malfunction caused by inter-phase heat interference of the heat element, which has been a problem in the conventional structure, and the reliability of the thermal relay is improved.

Hereinafter, embodiments of the present invention will be described based on the examples shown in FIGS. In addition, in the figure of an Example, the same code | symbol is attached | subjected to the member corresponding to FIG. 4, and the description is abbreviate | omitted.
First, in the embodiment shown in FIGS. 1A to 1C, the left and right side edges of the bimetal 6 are provided with the winding pitch p of the heater wire 8 and the concave groove 6b for positioning in accordance with the wire diameter. The heater wire 8 that is formed along the edge and wound around the bimetal 6 spans the zigzag between the concave grooves 6b and is wound around the zigzag. Further, in the assembled state in which the heater wire 8 is wound around the bimetal 6 and connected to the terminals 9 and 10, the surface is heat-resistant by applying a material having excellent heat resistance and voltage resistance such as silicone rubber to the assembly. It is made to cover with the coating layer 11.
With the above configuration, the pitch deviation of the heater wire 8 wound around the bimetal 6 can be prevented as described above to stabilize the bending operation characteristics of the heat element, and the heat element assembly is covered with the heat resistant coating layer 11. As a result, the power consumption can be reduced, and the thermal interference between phases can be suppressed to improve the reliability of the operating characteristics of the thermal relay.

Next, some application examples regarding the concave groove 6b formed in the bimetal 6 are shown in FIGS.
That is, in FIG. 1 (b), the concave grooves 6b formed on the left and right side edges of the bimetal 6 are arc-shaped, but in the embodiment shown in FIGS. 2 (a) and 2 (b), the shape of the concave grooves 6b is V. Grooves and square grooves.
Further, in the embodiment shown in FIGS. 2C and 2D, the concave groove 6b is formed on both the front and back surfaces of the bimetal 6, and the heater wire is wound along the concave groove. In this embodiment, the concave groove 6b is a square groove according to the heater wire of the flat conductor, but it may be an arc groove or a V groove according to the sectional shape and wire diameter of the heater wire.
On the other hand, in the embodiment shown in FIG. 2 (e), the positioning groove of the heater wire is continuously formed as a gently tapered groove 6d so as to have a wave shape along the side edge of the bimetal 6, and In the embodiment of FIG. 2 (f), the arcuate groove 6a shown in FIG. 1 (b) is combined with the deepest portion of the groove 6d. According to this embodiment, in the process of winding the heater wire 8 around the outer circumference of the bimetal 6 while applying tension, the self-alignment function works so that the tapered groove guides the heater wire to the deepest part, and the heater wire is arranged at a predetermined pitch p. It can be wound in line with the position.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram of the heat element by the Example of this invention, (a) is a front view of a finished product, (b) is a shape figure of the bimetal in (a), (c) is a heater wire wound around the bimetal of (b) Rotated state diagram In the application example of the bimetal in FIG. 1, (a), (b), (c), (e), (f) are front views of embodiments having different groove shapes, and (d) is (c). Side view Configuration diagram of thermal relay FIG. 3 is a conventional structural view of the heat element in FIG. 3, (a) is a front view in an assembled state, (b) is a shape diagram of the bimetal in (a), and (c) is a state diagram in which a heater wire is wound around the bimetal.

Explanation of symbols

2 Heat element 3 Shifter 4 Contact mechanism 6 Bimetal 6a Operation end 6b, 6c, 6d Groove 8 Heater wire 9, 10 Terminal

Claims (4)

A heat element corresponding to each phase of the main circuit of the thermal relay linked to the contact mechanism through a shifter, the heat element having the operation end opposed to the shifter and fixing the other end to the terminal. In what consists of a bimetal connected to the heater and a heater wire wound around the periphery of the bimetal and connected in series,
A heating element for a thermal relay, wherein a concave groove for positioning that holds the heater wire at a predetermined winding position is formed in the bimetal in accordance with a winding pitch of the heater wire. 2. The heat element according to claim 1, wherein concave grooves are formed on left and right side edges of the bimetal. The heat element according to claim 1, wherein the groove is formed on both front and back surfaces of the bimetal. The heat element according to any one of claims 1 to 3, wherein a surface of the bimetal and the heater wire is covered with a heat-resistant heat insulating material in an assembled state in which the heater wire is wound around the bimetal. Heat element.

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