JP2011238466A - Thermal overload relay - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a shape of a release lever by which a reverse spring is operated in order to stabilize an operation current value of a thermal overload relay.SOLUTION: The thermal overload relay has an outer shell case in which a main bimetal bent and displaced by conduction of an overcurrent, a shifter displaced responding to the bending of the main bimetal, a release lever rotated by the displacement of the shifter through a support shaft, and a contact reversing mechanism driven by the release lever are internally installed. The contact reversing mechanism comprises an assembly of a reverse spring linked with the release lever, a slider coupled to the reverse spring, an output contact which performs open/close operation in response to the movement of the slider, and a reset button. A press part of the release lever, which presses an action part of the reverse spring in order to trip the reverse spring, is made to have a line contract structure against the axial direction of the support shaft.

Description

  The present invention relates to a thermal overload relay (thermal relay) used in combination with an electromagnetic contactor and the like, and more particularly to a contact reversing mechanism for switching contacts when an overcurrent is detected.

First, a typical conventional structure of the above-described thermal overload relay is shown in FIG. 4 (see, for example, Patent Document 1).
In FIG. 4, 1 is an outer case made of resin mold, 2 is a main bimetal that is curved by receiving heat generated by a heater 2a connected to the main circuit, 3 is a shifter linked to the free end of the main bimetal 2, and 4 is a shifter 3 The release lever 5 is driven by the release lever 4, and is an opening / closing mechanism for the output contact. The opening / closing mechanism 5 includes a reversing spring 6 linked to the releasing lever 4, and a slider 7 connected to the reversing spring 6. The output contacts 8 (a contact) and 9 (b contact) that open and close in response to the movement of the slider 7 and the reset switch 10 are assembled. Reference numeral 11 denotes an adjustment link that pivotally holds the release lever 4 so that it can swing. Reference numeral 12 denotes an adjustment dial that links the upper end side of the adjustment link 11 to adjust the settling current.
The operation of the thermal overload relay is well known, and when the main bimetal 2 bends due to the overload current flowing in the main circuit, the release lever 4 rotates around the support shaft 11b via the shifter 3 and reverses. The spring 6 is reversed, the slider 7 of the opening / closing mechanism 5 is driven, the output contacts 8 and 9 are reversed, and the contact signal is output.

JP-A-2-86024

By the way, in the above-described conventional thermal overload relay, when the main bimetal is bent due to overcurrent, the release lever rotates around the support shaft via the shifter to reverse the reversing spring. As shown in the figure, the shape of the pressing portion of the release lever for reversing the reversing spring is convex and has an R portion, and the action portion where the pressing portion of the releasing lever pushes the reversing spring is also R-shaped, A point contact structure is formed orthogonal to each other at the position P. This release lever has a structure that rotates around a support shaft, and in order to make the rotation smooth, a certain backlash is provided in the axial direction of the support shaft. That is, as shown in FIG. 7B, the pressing portion that comes into contact with the reversing spring due to this play may be displaced from the position P in the axial direction of the support shaft.
The reversing spring is a leaf spring in which the thin plate is bent and the action part is formed in a bowl shape. When the action part of the release lever and reversing spring is pushed in and the internal stress in the reversing spring exceeds a certain level, The shape of the bowl is reversed. For this reason, when the contact position of the action part changes, the generation state of the internal stress changes, so that the push-in amount until it reverses changes.
Since the thermal overload relay is a structure that operates the reversal spring by bending of the main bimetal due to heat generation of current, the amount of push-in until the reversal spring operates changes the thermal overload relay. The current value changes, and there is a problem that stable operation cannot be performed.
The present invention has been made in view of the above points, and an object of the present invention is to always keep the amount of pushing of the reversing spring constant even if the pressing portion of the release lever and the acting portion of the reversing spring are misaligned. It is an object of the present invention to provide a thermal overload relay capable of stabilizing the operating current value.

In order to achieve the above object, according to the present invention, a main bimetal that is curved and displaced by energization of an overcurrent, a shifter that is displaced in response to the curvature of the main bimetal, and a pivot that is rotated by the displacement of the shifter. In the thermal overload relay in which the release lever and the contact reversing mechanism driven by the release lever are installed in the outer case, the contact reversing mechanism is connected to the reversing spring linked to the releasing lever and the reversing spring. It consists of an assembly of a slider, an output contact that opens and closes in response to the movement of the slider, and a reset button, and the release part of the release lever that presses the reversing spring to trip the reversing spring in the axial direction of the support shaft On the other hand, a line contact structure is adopted (claim 1), and specifically, it is configured in the following manner.
(1) The shape of the pressing portion of the release lever is an arc shape (claim 2).
(2) The pressing part dimension of the release lever is made larger in the axial direction than the action part dimension of the reversing spring.

  According to the above configuration, the release lever pressing portion and the reversing spring acting portion have a line contact structure, so that the release lever is always in line contact even if the axial direction of the support shaft is displaced. The amount of push-in until the spring is reversed becomes constant, and the operating current can be stabilized.

The front view which shows the internal structure of the thermal overload relay which shows the Example of this invention Enlarged perspective view of release lever and reversal spring part of the present invention Enlarged perspective view of the release lever shown in FIG. Front view showing the internal structure of a thermal overload relay showing a conventional example Enlarged perspective view of conventional release lever and reversing spring Enlarged perspective view of the release lever shown in FIG. 5A is an enlarged perspective view showing a normal positional relationship between the release lever and the reversing spring portion shown in FIG. 5, and FIG. 5B is a position shift of the release lever and the pressing portion of the reversing spring portion from the state of FIG. Enlarged perspective view showing the state

  Embodiments of the present invention will be described below based on the illustrated embodiments. 1 to 3 are configuration diagrams of the thermal overload relay corresponding to 1-2 of this embodiment, and the members corresponding to FIGS. .

The thermal overload relay of this embodiment shown in FIG. 1 includes a release lever 4 that is driven by the displacement of a shifter 3 engaged with the free end of the main bimetal 2 in the outer case 1, and an operation of the release lever 4. A contact opening / closing mechanism 5 for switching the contacts and a reset button 10 for resetting the contact opening / closing mechanism 5 are provided.
The contact opening / closing mechanism 5 includes an adjustment link 11, a release lever 4 rotatably supported on a support shaft 11 b of the adjustment link 11, a compensation bimetal 4 a fixed to the release lever 4 and engaged with the shifter 3. It has.
The operation of the thermal overload relay with the above configuration is the same as that of the conventional structure. The overcurrent exceeding the set current set by the adjustment dial 12 flows in the main circuit, the main bimetal 2 is bent, and compensated through the shifter 3 When the bimetal 4a is displaced, the release lever 4 rotates counterclockwise about the connecting shaft with the adjustment link 11 and pushes the reversing spring 6. As a result, the reversing spring 6 snaps and the output contacts 8 and 9 switch.
Here, the relationship between the release lever 4 and the reversal spring 6 is such that the pressing portion 4b of the release lever 4 that presses the action portion 6a of the reversal spring 6 to trip the reversal spring 6, as shown in FIGS. The structure is such that line contact is made with respect to the axial direction of the support shaft 11b.
Thereby, even if the release lever 4 is displaced in the axial direction of the support shaft 11b, the release lever 4 is always in line contact, so that the pushing amount until the reversing spring 6 is reversed becomes constant, and the operating current can be stabilized. .

  The size 4c of the pressing portion 4b of the release lever 4 is preferably larger than the size 6c of the action portion 6a of the reversing spring 6.

DESCRIPTION OF SYMBOLS 1 Outer case 2 Main bimetal 3 Shifter 4 Release lever 4a Compensation bimetal 4b Press part 5 Contact opening / closing mechanism 6 Reversing spring 6a Action part 7 Slider 8, 9 Output contact 10 Reset switch 11 Adjustment link 11a Bearing part 11b Support axis 12 Adjustment dial

Claims (3)

  A main bimetal that is bent and displaced by energization of an overcurrent, a shifter that is displaced in response to the bending of the main bimetal, a release lever that is rotated via a support shaft by the displacement of the shifter, and a contact reversing mechanism that is driven by the release lever In the thermal overload relay installed in the outer case, the contact reversing mechanism has a reversing spring linked to the release lever, a slider coupled to the reversing spring, and an output that opens and closes in response to the movement of the slider. It consists of an assembly of a contact point and a reset button, and the pressing part of the release lever that presses the action part of the reversing spring to trip the reversing spring has a line contact structure with respect to the axial direction of the support shaft. Thermal overload relay.   2. The thermal overload relay according to claim 1, wherein the shape of the pressing portion of the release lever is an arc. 2. The thermal overload relay according to claim 1, wherein the pressing portion of the release lever is larger in the axial direction than the acting portion of the reversing spring.

Images