WO2024042746A1

WO2024042746A1 - Thermal overload relay

Info

Publication number: WO2024042746A1
Application number: PCT/JP2023/007915
Authority: WO
Inventors: 守連李; 悠真小野木; 颯斗三浦
Original assignee: 富士電機機器制御株式会社
Priority date: 2022-08-26
Filing date: 2023-03-02
Publication date: 2024-02-29

Abstract

In the present invention, a trip operation of a reversal mechanism (24) is performed by a differential lever (23) being pivoted by being pushed against a push shifter (22a) from the outside in the radial direction with a position at which the differential lever engages with a pull shifter (22b) as the pivot center, and a compensation bimetal contact surface (74) that is provided to the differential lever displacing a compensation bimetal (31). In addition, there is provided a compensation bimetal displacement amplifying means that amplifies the displacement of the compensation bimetal by, in an overloaded state in which an overcurrent flows, stopping of the displacement of the pull shifter and a subsequent displacement of the push shifter, whereby the differential lever is pivoted.

Description

Thermal overload relay

The present invention relates to a thermal overload relay.

In thermal overload relays, when overcurrent continues to flow, the heat causes the bimetal to bend, tripping the relay and shutting off the electromagnetic contactor or molded circuit breaker, thereby protecting the main circuit from overload. . In the thermal overload relay of Patent Document 1, when the bimetal placed between the plurality of partition walls provided inside the case is heated by the heater and curved, the push shifter and the pull shifter are displaced and the differential lever is moved. The displacement of the differential lever is transmitted to the compensating bimetal of the reversing mechanism, resulting in a trip state.

Japanese Patent Application Publication No. 2011-165492

By the way, in the thermal overload relay of Patent Document 1, the bimetal may curve and come into contact with the partition wall provided inside the case before starting the tripping operation. The bimetal in an overloaded state (a state in which overcurrent continues to flow) is at a high temperature, and there is a risk that the partition wall that the high-temperature bimetal comes into contact with may burn out.
An object of the present invention is to provide a thermal overload relay that can reduce the risk of damage caused by contact of a high-temperature bimetal with a partition wall of a case by early starting a trip operation in an overload state.

A thermal overload relay according to one aspect of the present invention includes a plurality of partition walls provided inside a case, a plurality of bimetals individually housed between the plurality of partition walls, and a plurality of bimetals that cover ends of the plurality of partition walls. a push shifter and a pull shifter that are arranged as shown in FIG. This is a thermal overload relay equipped with a reversing mechanism that reverses the contacts and performs a trip operation by transmitting the lever driven action to a compensating bimetal. The differential lever rotates by being pushed from the outside in the radial direction by the push shifter, with the position where it engages with the pull shifter as the center of rotation, and the compensation bimetal contact surface provided on the differential lever displaces the compensation bimetal. The reversing mechanism is tripped. Then, in an overload state where an overcurrent is flowing, the displacement of the pull shifter stops first, and then the push shifter continues to displace, rotating the differential lever and amplifying the displacement of the compensation bimetal.Compensation bimetal displacement Amplification means are provided.

According to the thermal overload relay of the present invention, by performing a tripping operation in an overload state early, it is possible to reduce the risk of damage caused by the high temperature bimetal contacting the partition wall of the case.

1 is a diagram showing the inside of a thermal overload relay according to an embodiment of the present invention with a cover removed; FIG. FIG. 2 is a perspective view showing the inside of the thermal overload relay from the side where an adjustment dial is provided. It is a perspective view showing the inside of a thermal overload relay from the side where a push shifter, a pull shifter, and a differential lever are arranged. FIG. 3 is a diagram showing the positions of a push shifter, a pull shifter, and a differential lever in a normal state in a thermal overload relay. It is a perspective view showing a differential lever of one embodiment. FIG. 2 is a side view and a sectional view showing a differential lever of one embodiment. It is a figure which shows the state in which a push shifter and a pull shifter are displaced in an overload state in a thermal type overload relay, and a differential lever is driven.

Next, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings below, the same or similar parts are designated by the same or similar symbols. However, it should be noted that the drawings are schematic and the relationship between thickness and planar dimensions, the ratio of the thickness of each layer, etc. are different from reality. Therefore, the specific thickness and dimensions should be determined with reference to the following explanation. Furthermore, it goes without saying that the drawings include portions with different dimensional relationships and ratios.
In addition, the embodiments shown below exemplify devices and methods for embodying the technical idea of the present invention. etc. are not specified as those listed below. The technical idea of the present invention can be modified in various ways within the technical scope defined by the claims.
In the following description, for convenience, three mutually orthogonal directions are referred to as a vertical direction, a width direction, and a depth direction.

[Configuration of thermal overload relay]
1 to 3 are views showing the inside of a case 12 of a thermal overload relay 11 according to an embodiment of the present invention with a cover (not shown) removed.
As shown in FIG. 1, inside the case 12 of the thermal overload relay 11, three-phase U, V, and

W bimetals

21U, 21V, and 21W, a shifter 22, a differential lever 23, and an inverted It includes a mechanism 24 and a reset rod 25.
The three-

phase bimetals

21U, 21V, and 21W extend in the depth direction and are formed in a plate shape along the vertical and depth directions, with the front side in the depth direction being a fixed end and the back side being a free end. Each bimetal 21 is connected to the main terminal on the front side in the depth direction, and is joined to one end of the heater 26 on the back side in the depth direction. The heater 26 is wound around three-

phase bimetals

21U, 21V, and 21W, and the other end is joined to the connection terminal 27 on the front side in the depth direction. The connection terminal 27 is connected to an electromagnetic contactor (not shown). The three-

phase bimetals

21U, 21V, and 21W are straight in a normal state, but in an overload state (a state in which overcurrent continues to flow), the free ends 21Ua, 21Va, and 21Wa curve toward the other side in the width direction. and press shifter 22.

The reversing mechanism 24 is a mechanism that reverses the contacts when an overcurrent is detected, that is, closes the A contact and opens the B contact, and as shown in FIGS. 1 and 2, it includes a compensation bimetal 31, a release lever 32, , a tension spring 33, a movable plate 34, a leaf spring 35, an interlocking plate 36, and an adjustment dial 37.
The compensating bimetal 31 extends in the depth direction and is formed in a flat plate shape along the depth direction and the longitudinal direction, the front side in the depth direction is fixed to the release lever 32, the back side in the depth direction is a free end, and the compensation bimetal 31 is attached to the differential lever 23. engaged.
The release lever 32 extends in the depth direction, is formed in a plate shape along the depth direction and the vertical direction, is rotatably supported by a support shaft along the vertical direction, and the back side in the depth direction is connected to the tension spring 33. are in contact. The tension spring 33 pulls the movable plate 34 toward the back side in the depth direction.
The case 12 is provided with an adjustment dial 37 for setting a setting current, and an eccentric cam 37a is provided on the circumferential surface of an eccentric cam 37a that is integrally provided on the back side of the adjustment dial 37 in the depth direction. The side ends are engaged. Then, when the adjustment dial 37 is turned, the free end of the compensation bimetal 31 is displaced in the width direction via the release lever 32 that engages with the circumferential surface of the eccentric cam 37a.

The movable plate 34 has a flat plate shape along the depth direction and the vertical direction, and the front side in the depth direction can be displaced in the width direction using the back side in the depth direction as a fulcrum. The upright position of the movable plate 34 serves as a fulcrum, and when a force is applied to one side or the other side in the width direction, the movable plate 34 tilts to one side or the other side in the width direction due to the tensile force of the tension spring 33. The movable plate 34 is normally tilted to one side in the width direction, but when an overload condition occurs, the movable plate 34 is pushed by the release lever 32 via the compensating bimetal 31 and tilted to the other side in the width direction. The movable plate 34 is connected to one of the auxiliary terminals on the back side in the depth direction, and has a movable contact formed on the front side in the depth direction.

The leaf spring 35 extends in the depth direction and has a flat plate shape along the depth direction and the vertical direction, and the back side in the depth direction is connected to the other auxiliary terminal, and the front side in the depth direction facing the movable plate 34 is fixed. A contact is formed. Normally, the movable contacts of the movable plate 34 are separated from the fixed contacts of the leaf spring 35, but when overloaded, the movable plate 34 tilts to the other side in the width direction, causing the fixed contacts of the leaf spring 35 to The movable contact of the movable plate 34 comes into contact with. These fixed contacts and movable contacts constitute an a contact, and when the a contact closes, it is in a trip state.

The interlocking plate 36 is formed into a plate shape along the width direction and the depth direction, is rotatably supported by a support shaft along the vertical direction, and the back side in the depth direction engages with the movable plate 34. . By rotating in conjunction with the movable plate 34, the interlocking plate 36 opens and closes the contacts on the back side of the interlocking plate 36, which is not shown in FIG. That is, in normal times, the movable contact is in contact with the fixed contact, but when an overload occurs, the interlocking plate 36 rotates, thereby separating the movable contact from the fixed contact. These fixed contacts and movable contacts constitute a b contact, and when the b contact opens, it is in a trip state.

The reset rod 25 is an operator for recovering from a tripped state, and is formed in a substantially cylindrical shape with the depth direction as the axis direction, and is arranged on the other side of the case 12 in the vertical direction and on the other side in the width direction. has been done. The reset rod 25 is supported by the case 12 in a state in which it can be displaced in the depth direction and rotated around an axis, and is further urged toward the front side in the depth direction by a leaf spring (not shown) extending in the vertical direction. ing. The reset rod 25 has an initial position, a manual reset position, and an automatic reset position. The initial position is a position where the front side in the depth direction protrudes beyond the case 12. The manual reset position is a position that is simply pushed back in the depth direction from the initial position. The automatic reset position is a position where the position in the depth direction is maintained by being pushed to the back side in the depth direction from the initial position and turned clockwise by about 90 degrees when viewed from the front side in the depth direction.

When the reset bar 25 is pushed to the back in the depth direction in the tripped state, the leaf spring 35 and the movable plate 34 are pushed to one side in the width direction by the end on the back side in the depth direction, so the overload condition is resolved. If so, open the a contact again and close the b contact. On the other hand, if the reset rod 25 is pushed to the back side in the depth direction in the tripped state and is turned clockwise by about 90 degrees when viewed from the front side in the depth direction, the reset rod 25 will move to the position in the depth direction. is retained. Since the leaf spring 35 and the movable plate 34 are pushed to one side in the width direction by the end on the back side in the depth direction, when the overload condition is resolved, the a contact is automatically opened again and the b contact is opened. close.

As shown in FIG. 3, the shifter 22 is composed of an insulating push shifter 22a and a pull shifter 22b that are supported by the case 12 so that their thickness directions are on the same plane. When an overload condition occurs, the three-

phase bimetals

21U, 21V, and 21W curve and the free ends 21Ua, 21Va, and 21Wa move to the other side in the width direction, thereby displacing the push shifter 22a to the other side in the width direction. , the pull shifter 22b and the differential lever 23 are displaced along with the displacement of the push shifter 22a. Furthermore, when an open phase occurs, the non-curving bimetal of the phase where the open phase occurs restricts the displacement of the pull shifter 22b, so that the push shifter 22a is displaced in the same way as when overloaded.

As shown in FIG. 3, the case 12 is formed with partition walls 41 to 43 arranged at predetermined intervals in the width direction inside the case 12, and a girder plate 44. On the other side of the

partition walls

41 and 43 in the vertical direction, protrusions 45a1 and 45a2 are arranged along the width direction and protrude in a columnar shape. On one side of the

partition walls

41 and 43 in the vertical direction, protrusions 45b1 and 45b2 are arranged along the width direction and protrude in a columnar shape.

As shown in FIG. 4, the push shifter 22a has an elongated hole 51 formed on one side in the width direction into which the projection 45a1 of the partition wall 41 fits, and a long hole 51 into which the projection 45b2 of the partition wall 42 fits into the other side in the width direction. A matching long hole 52 is formed. Further, the push shifter 22a has engaging pieces 53 to 55 formed on one side in the vertical direction, and a tip 56 that projects toward the other side in the width direction opposite to the engaging piece 55. There is.
As shown in FIG. 4, the pull shifter 22b has an elongated hole 58 formed on one side in the width direction into which the projection 45b1 of the partition wall 41 fits, and a long hole 58 into which the projection 45b2 of the partition wall 43 fits into the other side in the width direction. A long hole 59 is formed to fit into each other. Further, the pull shifter 22b is formed with engagement pieces 60 to 62 on the other side in the vertical direction, and the engagement pieces 60 to 62 are formed on the other side in the width direction of the pull shifter 22b. An engagement groove 65 is formed that extends into the groove.

FIG. 5 is a perspective view showing the differential lever 23, FIG. 6(a) is a view of the differential lever 23 seen from the other side in the width direction, and FIG. 6(b) is a perspective view of the differential lever 23. -A cross section is shown.
The differential lever 23 has a pair of opposing

plates

70 and 71 formed on one side in the vertical direction. The pair of opposing

plates

70 and 71 are formed in a flat plate shape extending in the vertical direction and the width direction, facing each other while being spaced apart in the depth direction, and are connected by a cylindrical support shaft 72 extending in the depth direction. The distance between the pair of opposing

plates

70 and 71 is slightly larger than the thickness of the digit plate 44 of the case 12, and the diameter of the support shaft 72 is slightly smaller than the groove width of the engagement groove 65 of the pull shifter 22b. On the other side of the differential lever 23 in the vertical direction, an end face 73 is formed that faces one side in the width direction and is a flat plane along the vertical direction and the depth direction. Further, on the other side of the differential lever 23 in the vertical direction, a compensating bimetallic contact surface 74 is formed, which is a curved surface along the depth direction that is convex toward the other side in the width direction.

As shown in FIG. 4, the push shifter 22a is configured such that the elongated hole 51 is fitted into the protrusion 45a1 of the partition wall 41 of the case 12, and the elongated hole 52 is fitted into the protrusion 45a2 of the partition wall 43, so that the push shifter 22a can be moved along the width direction. It is arranged so that it can be displaced. Further, the engagement piece 53 of the push shifter 22a engages with the free end 21Ua of the U-phase bimetal 21U from the other side in the width direction, and the engagement piece 54 engages with the free end 21Va of the V-phase bimetal 21V in the width direction. engage from the other side. The engagement piece 55 engages with the free end 21Wa of the W-phase bimetal 21W from the other side in the width direction.
As shown in FIG. 4, the pull shifter 22b is configured such that the elongated hole 58 is fitted into the protrusion 45b1 of the partition wall 41 of the case 12, and the elongated hole 59 is fitted into the protrusion 45b2 of the partition wall 43, so that the pull shifter 22b can be moved along the width direction. It is arranged so that it can be displaced. Further, the engagement piece 60 of the pull shifter 22b engages with the free end 21Ua of the U-phase bimetal 21U from one side in the width direction, and the engagement piece 61 engages with the free end 21Va of the V-phase bimetal 21V in the width direction. engage from one side. The engagement piece 62 engages with the free end 21Wa of the W-phase bimetal 21W from one side in the width direction.

As shown in FIG. 4, the differential lever 23 has a pair of opposing

plates

70 and 71 sandwiching the girder plate 44 of the case 12, and the support shaft 72 fits into the engagement groove 65, so that the support shaft 72 is attached to the case 12. It is rotatably supported around the center. An end surface 73 facing one side in the width direction of the differential lever 23 engages with the tip 56 of the engagement piece 55 of the push shifter 22a. The free end of the compensating bimetal 31 of the reversing mechanism 24 engages the compensating bimetallic contact surface 74 facing the other widthwise side of the differential lever 23 .

As shown in FIG. 4, in the normal state where the three-

phase bimetals

21U, 21V, and 21W are not curved, the push shifter 22a is connected to the protrusion 45a1 of the partition wall 41 fitted in the elongated hole 51 and the elongated hole 51. A gap of dimension D1 is provided between the opening edge 51a on one side in the width direction. Further, in the normal state, the pull shifter 22b has a gap of dimension D2 between the protrusion 45b1 of the partition wall 41 fitted into the elongated hole 58 and the opening edge 58a on one side in the width direction of the elongated hole 58. . The pull shifter 22b also has an elongated hole 59 formed on the other side in the width direction into which the protrusion 45b2 of the partition wall 43 fits, and the relationship between the elongated hole 58 and the protrusion 45b1 described above is similar to that of the elongated hole 59. A gap of dimension D2 is provided between the protrusion 45b2 and the opening edge on one side in the width direction of the elongated hole 59, but since they have the same function, in the following description, the elongated hole 58 and the protrusion will be referred to as the elongated hole 58 and the protrusion. Only the engaged state of 45b1 will be explained.

Here, in this embodiment, the amount of displacement of the free ends 21Ua, 21Va, 21Wa when the three-

phase bimetals

21U, 21V, 21W curve to the maximum in an overload state (hereinafter referred to as overload bimetal displacement amount) Set it as D3. The bimetal displacement amount D3 in this overload state is set smaller than the gap D1 of the push shifter 22a in the normal state (D3<D1). Further, the bimetal displacement amount D3 in the overcurrent state is set to be larger than the gap D2 of the pull shifter 22b in the normal state (D3<D2). Therefore, the relationship between the bimetal displacement amount D3 in the overload state, the gap D1 of the push shifter 22a in the normal state, and the gap D2 of the pull shifter 22b in the normal state is set as shown in equation (1) below. .
D2 < D3 < D1 ...Formula (1)

Furthermore, when the adjustment dial 37 is turned in the direction of a larger scale (increasing the setting current), the release lever 32 that engages with the circumferential surface of the eccentric cam 37a is rotated clockwise, and the compensation bimetal that is connected to the release lever 32 is rotated clockwise. The free end of 31 moves to the other side in the width direction. Here, the compensation bimetal 31 shown by the broken line in FIG. 4 is such that when the adjustment dial 37 is turned to the maximum scale (the scale that sets the setting current to the largest value), the compensation bimetal 31 is maximally displaced to the other side in the width direction. It's the location. When the adjustment dial 37 is turned to the maximum scale, the compensation bimetal 31 is displaced by a dimension D4 from the reference position of the compensation bimetal 31 shown by the solid line to the other side in the width direction. This dimension D4 is referred to as the compensation bimetal maximum displacement amount.
In this embodiment, the relationship between the compensation bimetal maximum displacement amount D4 and the gap D2 of the pull shifter 22b in the normal state is set as shown in equation (2) below.
D4 < D2...Formula (2)

[motion]
Next, the main operations of this embodiment will be explained with reference to FIGS. 4 and 7.
In the normal state shown in FIG. 4, the push shifter 22a and the pull shifter 22b are located on one side in the width direction, and the compensation bimetal 31 is arranged to extend in the vertical direction. The push shifter 22a provides a gap D1 between the protrusion 45a1 of the partition wall 41 fitted in the elongated hole 51 and the opening edge 51a on one side in the width direction of the elongated hole 51, and the pull shifter 22b A gap D2 is provided between the projection 45b1 of the partition wall 41 fitted into the hole 58 and the opening edge 58a on one side in the width direction of the elongated hole 58.

When the overcurrent begins to flow, the three-

phase bimetals

21U, 21V, and 21W are bent by the heating of the heater 26, and the free ends 21Ua, 21Va, and 21Wa move toward the other side in the width direction. As the free ends 21Ua, 21Va, and 21Wa move toward the other side in the width direction, the engagement pieces 53 to 55 of the push shifter 22a are pushed and displaced toward the other side in the width direction. Due to this displacement of the push shifter 22a, the protrusion 45a1 approaches the opening edge 51a on one side of the elongated hole 51 in the width direction, and the protrusion 45a2 approaches one side of the elongated hole 52 in the width direction. Further, along with the displacement of the push shifter 22a, the pull shifter 22b is also displaced to the other side in the width direction. Due to the displacement of the pull shifter 22b, the protrusion 45b1 approaches the opening edge 58a on one side of the elongated hole 58 in the width direction. Further, the differential lever 23 is also displaced to the other side in the width direction together with the push shifter 22a and the pull shifter 22b. Due to this displacement of the differential lever 23, the free end of the compensation bimetal 31 that is engaged with the compensation bimetal contact surface 74 of the differential lever 23 is also displaced toward the other side in the width direction.

As shown in FIG. 7, in an overload state where an overcurrent continues to flow, the push shifter 22a and the pull shifter 22b, which continue to be simultaneously displaced to the other side in the width direction, are pushed by the gap D2 of the pull shifter 22b. Since the gap D1 is smaller than the gap D1 of the shifter 22a (D2<D1), the protrusion 45b1 engages with the opening edge 58a on one side in the width direction of the elongated hole 58 of the pull shifter 22b, and the projection 45b1 engages with the opening edge 58a on the other side in the width direction of the elongated hole 58 of the pull shifter 22b. Displacement to stops.
Although the displacement of the pull shifter 22b stops, the push shifter 22a continues to be displaced toward the other side in the width direction due to the movement of the free ends 21Ua, 21Va, and 21Wa toward the other side in the width direction. Then, the tip 56 of the push shifter 22a pushes the end surface 73 of the differential lever 23 toward the other side in the width direction. The differential lever 23 rotates counterclockwise around the support shaft 72 that is engaged with the engagement groove 65 of the pull shifter 22b whose displacement has stopped, and the compensation bimetal contact surface 74 moves freely against the compensation bimetal 31. The end is displaced to the other side in the width direction. As a result, the reversing mechanism 24 enters a trip state in which the free end side of the compensation bimetal 31 is displaced to the other side in the width direction, thereby closing the a contact and opening the b contact.

[Effect]
Next, the effects of this embodiment will be explained.
In an overload state, when the push shifter 22a and the pull shifter 22b continue to be displaced simultaneously to the other side in the width direction, a projection of the partition wall 41 is formed on the opening edge 58a on one side in the width direction of the elongated hole 58 of the pull shifter 22b. By engaging the portion 45b1, the displacement of the pull shifter 22b is stopped. The push shifter 22a continues to be displaced to the other side in the width direction, and the tip 56 of the push shifter 22a presses against the end surface 73 of the differential lever 23. Due to this pressing operation of the push shifter 22a, the differential lever 23, whose support shaft 72 is engaged with the engagement groove 65 of the pull shifter 22b, rotates counterclockwise around the support shaft 72, thereby causing compensation bimetal contact. The surface 74 largely displaces the free end of the compensation bimetal 31 toward the other side in the width direction. In this way, in an overload state, the displacement of the pull shifter 22b stops first, and by rotating the differential lever 23 by the displacement of the push shifter 22a, the displacement of the free end of the compensation bimetal 31 is amplified, and the reversing mechanism 24 The trip operation can be started early.

Therefore, the tripping operation can be started early before the high-

temperature bimetals

21U, 21V, and 21W curve and come into contact with the partition walls 41-43, so the risk of damage to the partition walls 41-43 can be reduced.
Furthermore, as is clear from the relationship D2 < D3 in equation (1) above, the gap D2 in the normal state between the elongated hole 58 provided in the pull shifter 22b and the protrusion 45b1 of the partition wall 41 is Since the value is set to be smaller than the overload bimetal displacement amount D3 of 21U, 21V, 21W, the pull shifter is 22b stops, the differential lever 23 starts rotating, and the tripping operation of the reversing mechanism 24 can be reliably started.

Furthermore, even if the adjustment dial 37 is turned to the maximum scale due to an erroneous operation, the compensation bimetal 31 will be smaller than the gap D2 in the normal state of the pull shifter 22b, as is clear from the relationship D4 < D2 in equation (2) above. The small compensating bimetal is displaced only up to the maximum displacement amount D4. Therefore, in an overload state, the displacement of the free end of the compensation bimetal 31 is amplified as described above. Therefore, even if the adjustment dial 37 is turned to the maximum scale, the tripping operation of the reversing mechanism 24 can be started early to prevent damage to the electrical equipment.

11 Thermal overload relay 12

Case

21U, 21V, 21W Bimetal 21Ua, 21Va, 21Wa Bimetal free end 22 Shifter 23 Differential lever 24 Reversing mechanism 25 Reset rod 26 Heater 27 Connection terminal 31 Compensation bimetal 32 Release lever 33 Tension spring 34 Movable plate 35 Leaf spring 36 Interlocking plate 37 Adjustment dial

37a Eccentric cam

22a Push shifter

22b Pull shifter 41 to 43 Partition wall 44 Girder plate 45a1 Projection (push shifter projection)
45a2 Projection 45b1 Projection (pull shifter projection)
45b2 Projection 51 Long hole (push shifter long hole)
52 Long holes 53 to 55 Engagement piece 56 Tip 58 Long hole (pull shifter long hole)
59 Elongated holes 60 to 62 Engaging piece 65

Engaging grooves

70, 71 Opposing plate 72 Support shaft 73 End face 74 Compensating bimetal contact surface

Claims

Multiple partition walls provided inside the case,
a plurality of bimetals individually housed between the plurality of partition walls;
a push shifter and a pull shifter that are arranged to cover the ends of the plurality of partition walls, and that engage and displace the free end of the bimetal when the bimetal is curved;
a differential lever that is pushed and driven by the displacement of the push shifter and the pull shifter;
A thermal overload relay comprising: a reversing mechanism that transmits the driven force of the differential lever to a compensating bimetal to reverse the contact and perform a trip operation;
The differential lever is rotated by being pushed from the outside in the radial direction by the push shifter with a rotation center at a position where it engages with the pull shifter, and the compensation bimetal contact surface provided on the differential lever is rotated by the compensation bimetal contact surface provided on the differential lever. The tripping operation of the reversing mechanism is performed by displacing the
In an overload state where an overcurrent is flowing, the displacement of the pull shifter is first stopped, and the push shifter is subsequently displaced, thereby rotating the differential lever and amplifying the displacement of the compensation bimetal. A thermal overload relay characterized by being equipped with a bimetal displacement amplification means.
The compensation bimetal displacement amplification means
a push shifter elongated hole whose longitudinal axis extends in the displacement direction of the push shifter;
a pull shifter elongated hole whose longitudinal axis extends in the displacement direction of the pull shifter;
a push shifter projection protruding from an end of the partition wall and slidably fitting into the push shifter elongated hole;
a pull shifter protrusion protruding from an end of the partition wall and slidably fitting into the pull shifter elongated hole;
The distance between the push shifter being displaced from the normal state in which the bimetal is not curved and the push shifter protrusion engaging one opening edge in the long axis direction of the push shifter elongated hole is D1;
The distance from when the pull shifter is displaced from the normal state until the pull shifter protrusion engages with one opening edge in the longitudinal direction of the pull shifter elongated hole is D2;
If the displacement amount of the free end when the bimetal is curved to the maximum in the overload state is D3,
2. The thermal overload relay according to claim 1, wherein the thermal overload relay is set to the following equation (1).
D2 < D3 < D1... Formula (1)
An adjustment dial is provided for adjusting the setting current, and when the scale of the adjustment dial is turned in a direction that increases the setting current, the compensation bimetal of the reversing mechanism is moved against the compensation bimetal contact surface of the differential lever. are set to be separated by a predetermined displacement,
When the scale of the adjustment dial is turned in the direction where the setting current is maximized, if the maximum displacement of the compensation bimetal is D4, the pull shifter engages with the pull shifter protrusion from the normal state and stops. 3. The thermal overload relay according to claim 2, wherein the relationship between the interval D2 and the interval D2 is expressed by the following equation (2).
D4 < D2... Formula (2)