JP3877026B2 - Thermal overload relay - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal overload relay, and more particularly to a means for preventing erroneous operation of a reset bar for returning an operation portion that has been reversely operated by an overcurrent.
[0002]
[Prior art]
First, the overall configuration of the thermal overload relay will be briefly described with reference to FIGS. 5 and 6. Here, FIG. 5 is a front view showing the inside with the cover removed, and FIG. 6 is a sectional view taken along the line VI-VI. 5 and 6, the thermal overload relay is configured to be housed in a mold container including a box-like case 1 having a convex front shape and a plate-like cover 2 covering the opening surface. The side main terminal 3 is fixed to the case 1 with screws 4, and the power source side main terminal 5 is fixed together with L-shaped relay terminals 7 with screws 6. One end of the bimetal 8 and the heater 9 constituting the thermal element is joined to the load side main terminal 3, and the other end of the inverted U-shaped heater 9 is joined to the relay terminal 7.
[0003]
A shifter 10 is combined with the free end of the bimetal 8, and this shifter 10 is supported by the case 1 so as to be slidable in the left-right direction in FIG. Above the shifter 10, a V-shaped release lever 11 is rotatably provided with a pin 12 as a fulcrum, and one end thereof is engaged with the shifter 10. Note that one end of the compensation bimetal is joined to the pin 12 and the other end of the compensation bimetal is pushed by the cam surface of the adjustment dial, but the description thereof is omitted. The illustrated thermal overload relay is provided with two sets of relay contacts, a normally closed contact and a normally open contact. First, the fixed leaf spring 13 of the normally closed contact is cantilevered by one normally closed terminal 14. A normally closed fixed contact 13a is attached to the tip. The other normally closed terminal 15 has a gate shape at the tip, and one end of a reversing plate 16 that also serves as a movable leaf spring of a normally closed contact is inserted in a V-groove formed in one leg portion so as to be swingable. A normally closed movable contact 16a is attached to the other end. An insulating plate 17 is attached to the back surface of the reversing plate 16. A serrated V groove is formed on the other leg of the normally closed terminal 15, and the other end of the tension spring 18 having one end hung on the V groove is hung on the reversing plate 16. The tension spring 18 is in contact with a pin 19 fixed to the other end of the release lever 11.
[0004]
Next, the normally open contact fixed leaf spring 20 is cantilevered by one normally open terminal 21, and a normally open fixed contact 20 a is attached to the inside of the tip. Further, the normally open contact movable plate spring 22 is cantilevered by the other normally open terminal 23, and a normally open movable contact 22a is attached to the tip thereof.
[0005]
On the other hand, a reset bar 24 is provided above the normally open fixed leaf spring 20. The reset bar 24 is guided to the case 1 so as to be slidable in the vertical direction in FIG. 5. The reset bar 24 is a stepped portion having a head (operation unit) at the upper end and a guide unit having a smaller diameter. The engaging projection 24a is integrally formed so as to protrude to the front perpendicularly to the paper surface of FIG. 5 at the lower side of the guide portion, and the head is shifted by 90 degrees from the engaging projection 24a on the head. The abutting piece 24b is integrally formed so as to protrude in the left direction. The engaging protrusion 24a is slidably inserted into the groove 25 of the case 1 to prevent the reset bar 24 from rotating, and to prevent the reset bar 24 from coming off by hitting the upper end of the groove 25. . As will be described later, the engagement protrusion 24a is extracted from the opening at the lower end of the groove 25 when the reset bar 24 is rotated. Although the detailed configuration is omitted, the portion of the reset bar 24 where the engaging protrusion 24a is provided is flexible because a slit is provided behind it, and the reset bar 24 is placed in the case. When being attached to 1, the engaging projection 24a is elastically retracted until it falls into the groove 25.
[0006]
In the above-described thermal overload relay, the current flows through the path of the power source side main terminal 5 → the relay terminal 7 → the heater 9 → the bimetal 8 → the load side main terminal 3, and the bimetal 8 heated by the Joule heat generated by the heater 9. Is curved as shown by the chain line in FIG. When the bimetal 8 bends, the shifter 10 moves to the left, and accordingly, the release lever 11 rotates clockwise around the pin 12 as a fulcrum. The release lever 11 pushes the tension spring 18 upward through FIG. When the energization current becomes an overcurrent state and the amount of push-up of the tension spring 18 increases, and the action of the tension spring 18 on the reversing plate 16 changes from counterclockwise to clockwise, the reversing plate 16 is in one stable state. Snap to the other stable state and reverse as shown in FIG.
[0007]
In FIG. 7, when the reversing plate 16 that also functions as a normally closed movable leaf spring is reversed, the normally closed contact is turned off as shown in the figure, while the normally open movable leaf spring 22 is pushed up via the insulating plate 17, and the movable contact 22a is moved. The normally open contact is turned on in contact with the fixed contact 20a. When the electromagnetic contactor (not shown) is released and the current is interrupted by the switching of the contacts, the bimetal 8 is cooled and the release lever 11 returns to the state shown in the figure, but the reversing plate 16 remains reversed. To return the reversing plate 16 to the initial state of FIG. 5, the reset bar 24 is pushed in the direction of the arrow in FIG. As shown in FIG. 8, the reset bar 24 that is pushed in deflects the fixed plate spring 20 and the movable plate spring 22 of the normally open contacts to push down the insulating plate 17, and the reversing plate 16 integrated therewith is in the state shown in FIG. Return to. Thereafter, when the hand is released, the reset bar 24 is lifted by the fixed leaf spring 20 which is elastically restored, and returns to the state shown in FIG.
[0008]
The reset operation is a manual reset, but there is a return method called automatic reset. This is to turn the reset bar 24 in advance and then turn it 90 degrees, and as shown in FIG. 9, the engaging protrusion 24 a that has come out of the groove 25 in FIG. 5 is locked to the stepped portion of the case 1. When the reset bar 24 is pushed in in this way, the normally open contact fixed leaf spring 20 is pushed down, and the distance C (FIG. 9) to the movable leaf spring 22 is narrowed. Therefore, even if the tension spring 18 is pushed by the release lever 11, the reversing plate 16 is disturbed by the fixed leaf spring 20 and cannot be reversed, and when the bimetal 8 cools, it automatically returns to the initial state.
[0009]
Here, in the reset operation, there is a possibility that the reset rod 24 is erroneously rotated at the time of manual reset, and the return method is switched to automatic reset. Therefore, in order to prevent this, the rotation of the reset bar 24 is normally prevented by a stopper piece, and the stopper piece is broken when switching to automatic reset. That is, FIG. 10 is a plan view of the main part as viewed from the top of FIG. 5, but the stopper piece 26 a is integrally formed on the display cover 26 that covers the reset rod mounting part of the case 1. In FIG. 10, the reset bar 24 is in the manual return position, and in order to switch to the automatic return position, the reset bar 24 is pushed 90 degrees from the illustrated position in the direction of the arrow, but the stopper piece 26a is the abutting piece 24b of the reset bar 24. It protrudes along the radial direction of the reset bar 24 so as to protrude in the middle of the rotation path. Since the stopper piece 26a hits the abutting piece 24b when trying to turn the reset bar 24, the reset bar 24 will not be inadvertently switched to the automatic return position. Switching Operation recombination to automatic return position of the reset rod 24 is made possible by taking folding stopper 26a as shown in FIG. 11.
[0010]
[Problems to be solved by the invention]
In the conventional configuration described above, is provided separately from the display cover 26 and the case 1, the stopper piece 26a to prevent Switching Operation recombination to automatic return position due to a malfunction of the reset rod 24 is formed in the display cover 26. That is, conventionally, the display cover 26 has to be provided in order to form the stopper piece 26a, which increases the number of parts. Accordingly, an object of the present invention is to prevent positional Switching Operation recombination reset rod due to a malfunction without increasing the number of parts.
[0011]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention is configured to integrally form a stopper piece on the rotation path of the abutting piece of the reset bar on the upper surface of the case in parallel with the sliding direction of the reset bar. Shall. The conventional stopper piece is formed along the radial direction of the reset bar. However, when such a stopper piece is molded integrally with the case, the structure of the mold becomes complicated and it is difficult to actually mold the stopper piece. Therefore, conventionally, a separate display cover is mounted on the case and a stopper piece is formed on the display cover. In contrast, according to the present invention, the stopper piece is provided so as to protrude in parallel with the sliding direction of the reset bar, and the stopper piece can be easily formed integrally with the case, so that it is necessary to provide a separate display cover. Absent.
[0012]
It is preferable that a groove is provided around the base of the stopper piece on the upper surface of the case , and the stopper piece can be folded from the base . As a result, when the stopper piece is folded from the base, the fracture surface is accommodated in the groove, and this fracture surface does not interfere with the abutting piece of the reset rod head and prevent the rotation.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to FIGS. In addition, the same code | symbol shall be used for the part corresponding to a prior art example. FIG. 1 is a plan view of a principal part of a thermal overload relay, and FIG. 2 is a sectional view taken along the line II-II. 1 and 2, the reset bar 24 is slidably guided by the case 1 as in the prior art, but the stopper piece 1a is provided on the upper surface of the case 1 in the sliding direction of the reset bar 24 (up and down in the figure). And are integrally formed so as to protrude in parallel with the direction. The stopper piece 1a protrudes on the rotation path of the abutting piece 24b protruding in the radial direction on the side surface of the head of the reset bar 24. The abutting piece 24b is formed in an inverted L shape when viewed from the side, but when the reset rod 24 is rotated 90 degrees in the direction of the arrow from the manual return position shown in FIG. 1 to rotate to the automatic return position. The abutting piece 24b hits the stopper piece 1a and is prevented from rotating.
[0014]
In order to switch the reset bar 24 to the automatic return position, the stopper piece 1a is folded from the base as shown in FIG. FIG. 4 is an enlarged view of portion A in FIG. 3. When the stopper piece 1a is folded as shown in FIG. 4, the fracture surface becomes a fine unevenness, and the lower surface of the abutting piece 24b remains as it is. There is a possibility of hitting. Therefore, in the illustrated embodiment, a groove 27 is formed around the base portion of the stopper piece 1a on the upper surface of the case 1 so that the fracture surface after folding is lower than the upper surface of the case 1. Thereby, the reset bar 24 is smoothly switched to the automatic return position without the abutting piece 24b interfering with the fracture surface.
[0015]
【The invention's effect】
As described above, according to the present invention, since the stopper piece for the reset bar can be integrally formed with the case, there is no need to provide a display cover as a separate part, and the number of parts is reduced accordingly, and the number of assembly steps and costs are reduced. Further, by providing the groove around the base of the stopper piece of the case upper surface in which case the return position Switching Operation recombination reset bar after removing the folding stopper piece becomes smooth.
[Brief description of the drawings]
FIG. 1 is a plan view of a principal part of a thermal overload relay showing an embodiment of the present invention.
2 is a cross-sectional view taken along line II-II in FIG.
3 is a view showing a state in which the stopper piece in FIG. 2 is broken. FIG.
4 is an enlarged view of a portion A in FIG.
FIG. 5 is a side view showing the inside of a thermal overload relay showing a conventional configuration.
6 is a cross-sectional view taken along line VI-VI in FIG.
7 is a side view of an essential part showing a state where the reversing mechanism in FIG. 5 is reversed. FIG.
8 is a side view of an essential part showing a state in which a reset bar in FIG. 7 is pushed.
9 is a side view of the main part showing a state where the reset bar in FIG. 5 is switched to the automatic return position.
10 is a plan view of relevant parts showing the top surface of FIG. 5;
11 is a diagram illustrating a state in which the stopper piece in FIG. 10 is broken.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Case 1a Stopper piece 3 Load side main terminal 4 Power supply side main terminal 8 Bimetal 9 Heater 10 Shifter 11 Release lever 16 Reversing plate 24 Reset rod 24a Engagement protrusion 24b Abutting piece
27 grooves

Claims (1)

While the contact is opened and closed by the reversing operation of the reversing mechanism linked to the thermal element, the reversing mechanism is equipped with a reset bar that returns the reversing mechanism to the stable state before reversing, and this reset bar is slidably guided by the case. A manual return position that is provided and pushed to return the reversing mechanism; and an automatic return position that is locked to the case and held in a pushed state at a position rotated from the manual return position; and The reset bar can be folded to prevent the reset position from being switched by an erroneous operation by interfering with the abutting piece of the head of the reset bar so that the reset bar protrudes in the middle of the rotation path that is switched from the manual return position to the automatic return position. In the thermal overload relay provided with a stopper piece ,
The stopper piece protrudes in parallel with the sliding direction of the reset bar on a rotation path of the abutting piece of the reset bar on the upper surface of the case, and is integrally formed with the case, and the base of the stopper piece on the upper surface of the case is formed. A thermal overload relay, characterized in that a groove is provided in the periphery and the stopper piece can be broken off from the base.

Images