JPS6328852Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an improvement of a long time reset type of an automatic reset type thermal overcurrent relay.

[Conventional example]

Conventionally, automatic reset type thermal overcurrent relays are often used to protect the motors of refrigerators.
In this case, the operating characteristics are generally required to operate in about 2 to 15 seconds with an overcurrent of 4 to 6 times, but the recovery time is conversely long and required to be 2 to 3 minutes or more.

In this case, although the operating time can be satisfied with the conventional technology, it has been difficult to lengthen the recovery time.

Figure 1 shows the main parts of the internal front view of a conventional thermal overcurrent relay, and 1 is a bimetal plate that bends from the dashed-dotted line in the diagram in the direction of the solid line when an overcurrent flows through the heater section (not shown). An interlocking plate 2 is engaged with the tip 1a. The interlocking plate 2 is pushed toward the left side in the figure by the bending of the bimetallic plate 1, and pushes the lower free end 3a of the release lever 3, which is engaged with the left end 2a. The release lever 3 is provided near a free end 3a that engages with the interlocking plate 2, a base 3b that is pivotally supported by a shaft 6 on an adjustment fitting 5 supported by the case 4, and an intermediate portion thereof, forming a toggle mechanism that will be described later. Contact piece 3c that contacts actuating plate 7
Since the free end 3a portion is usually formed of a bimetallic plate, FIG. 1 shows a separate piece that is fixed by welding or the like. Note that these may be integrally formed. The release lever 3 integrated in this way is rotatably supported around an axis 6.

The actuating plate 7 is made of an elastic body, and a movable contact 8 is fixed to the lower part thereof. In addition, the upper part has a mounting hole 7a as shown in Fig. 2, and the central part is provided with a tongue piece 7b, which is fixed to the case (not shown).
The upper and lower support parts 9a and 9b of the U-shaped base 9 are held between the upper end 7c of the mounting hole 7a and the tip 7d of the tongue piece 7b, and the tongue piece 7b
is an elastic plate and is in contact with the base 9 with a deflection amount, so the actuating plate 7 is elastically supported by the base 9. This actuating plate 7 is arranged so that the movable contact 8 fixed near its lower free end 7e is normally pressed against the fixed contact 10 side, and the upper end 7c of the upper mounting hole 7a and the tip 7d of the tongue piece 7b are connected to each other. A protrusion 7f provided approximately in the middle is formed so as to abut against the abutment piece 3c of the release lever 3, as shown in FIG. Then, as the release lever 3 rotates clockwise, the projection 7f of the actuating plate is pushed, and the actuating plate 7 curves and moves over the lower support part 9b on the line connecting the upper and lower supports 9a and 9b of the base 9. Since the dead center of the toggle mechanism is on the line connecting the U-shaped bases 9a and 9b on this lower support part 9b,
The toggle mechanism reverses after this dead center, and the movable contact 8
is dissociated from the fixed contact 10 and moves toward the stopper 11 as shown in FIG. In this case, the position of the stopper 11 requires automatic return of the contact, so as the release lever 3 rotates in the return direction, that is, counterclockwise, the actuating plate itself follows and the toggle mechanism can be automatically reversed again. It is selected as follows. That is, the movable contact fixing portion of the actuating plate 7 is set to be located toward the fixed contact 10 side from the extension line A-A' of the upper and lower support portions 9a and 9b of the base 9. In this way, the actuating plate 7, the base 9, the movable contact 8, the fixed contact 10, and the stopper 11 form a toggle mechanism.

To explain the operation of the conventional example configured in this way, first, an overcurrent flows due to an accident on the load side, the bimetal plate 1 is bent, and the release lever 3 is moved clockwise around the shaft 6 via the interlocking plate 2. This rotation causes the contact piece 3c of the release lever 3 to push the protrusion 7f of the actuating plate, and when the actuating plate 7 passes the dead center on the lower support part 9b of the base 9, the toggle mechanism is reversed, and the movable contact 8 moves away from the fixed contact 10 and toward the stopper 11. In this case, the stopping position of the actuating plate 7 at the portion to which the movable contact 8 is fixed is located on the side of the fixed contact 10 with respect to the extension line A-A' connecting the support parts 9a and 9b of the base 9. Due to this opening operation of the contacts, a switch (not shown), etc. is suddenly opened, and no overcurrent flows, and the bimetal plate 1
is cooled, and the curved deformation gradually recovers.

Along with this restoring operation of the bimetal plate, the actuating plate 7 moves in the return direction while pushing back the contact piece 3c of the release lever with the protrusion 7f due to its elasticity, and crosses the dead center on the lower support part 9b of the base 9. When the toggle mechanism is restored to the original position, the toggle mechanism is reversed and the movable contact 8 automatically returns to the fixed contact 10 side.

[Problem that the invention attempts to solve]

According to the conventional embodiment, in order to cause the contact to return automatically, as shown in FIG. It is necessary to position the stopping position of the plate 7 toward the fixed contact 10 side with respect to the extension line A-A' of the upper and lower support parts 9a and 9b of the base 9, so that the toggle mechanism returns and reverses from the point at which the operation is reversed. There is a limit to the movement distance of the actuating plate 7 up to this point, and there is also a limit to the return stroke, which is the movement distance of the release lever tip 3a, which can be expressed in proportion to this movement distance. Figure 3 shows the bending characteristics of a bimetal plate during cooling.In the case of the return stroke length from the bending point during operation on the vertical axis, the return time is T1, whereas in the return stroke, the return time is three times T1. The return time T2 can be obtained.
In other words, if the ratio of the return stroke to the bending point during operation on the vertical axis is increased, the return time can be lengthened. However, in the conventional automatic return type thermal overcurrent relay, it has not been possible to increase the return stroke beyond a certain degree, as described above. Furthermore, even if the return stroke can be increased, the movement of the release lever tip 3a until the release lever 3 rotates clockwise due to the bending of the bimetal plate due to overcurrent and the toggle mechanism reverses its operation will occur even if the return stroke can be increased. If you get too close to
The accuracy of return was impaired and there was a possibility that a return failure would occur. Conversely, it is possible to lengthen the return time by making the operating stroke closer to the return stroke and increasing the ratio of the return stroke to the operating stroke, but if the operating stroke becomes too small, the adjustment range of the operating current value during overload will be reduced. (1st
The adjustment range (with the current adjustment dial DY shown in the figure) is narrowed and the adjustment is no longer possible.For this reason, with the conventional automatic return type, the return time is 2.
It was difficult to extend the time by more than 3 minutes.

Therefore, conventionally, as a countermeasure against this problem, a separate reset timer or the like has been provided, making the circuit complicated and expensive. (Illustration omitted) The present invention solves these drawbacks by increasing the return stroke after reversing the toggle mechanism operation during overload, so that the actuating plate that forms the toggle mechanism cannot return automatically by itself, and when returning The object of the present invention is to provide an automatic return type thermal overcurrent relay that has a long return time and that transmits the restoring force of the bimetal plate during cooling to the actuating plate via the interlocking plate to reverse and return the toggle mechanism. That is.

[Means for solving problems]

To achieve this purpose, the present invention transmits the amount of thermal bending of the bimetal plate to the release lever through the interlocking plate, and the rotation of the release lever pushes the actuating plate forming the toggle mechanism to reversely drive the contact. In the thermal overcurrent relay, the interlocking plate includes a stopper disposed to stop the actuating plate after reversing the operation of the toggle mechanism at a position beyond the dead center of the toggle mechanism; The invention is characterized by the provision of a protrusion that engages and pushes the actuating plate in the return direction when the bimetal plate is restored, and a protrusion that engages with and is pushed by at least one bimetal plate when the bimetal plate is restored.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 4 and 5 show the main parts of the internal front view of the present invention, FIG. 4 shows the operating state and FIG. 5 shows the non-operating state, and the same symbols as the conventional example are the same or The corresponding parts are shown. In the figure, 1 is a bimetal plate, 20 is an interlocking plate, 3 is a release lever, and 4
is a case, 5 is an adjustment fitting, 6 is a shaft, 7 is an operating plate,
8 is a movable contact, 9 is a base, 10 is a fixed contact, 11
is a stopper, and the structure thereof is almost the same as that of the conventional example shown in FIG. Here, the difference from the conventional example is that the position of the stopper 11 that stops the movable contact 8 after the toggle mechanism reverses its operation due to an overload is further toward the operating direction side (leftward in the figure) compared to the conventional example. This is because the toggle mechanism of the actuating plate 7 itself is selected to be in such a position that it does not reverse and return when the release lever 3 returns, and the shape of the conventional interlocking plate 2 has been improved as shown in FIG. That is, the movable contact fixing portion of the actuating plate 7 is selected to be located toward the stopper 11 side from the extension line A-A' of the upper and lower support portions 9a and 9b of the base 9. Therefore, the return stroke is also longer than that of the conventional example shown in FIG. Therefore, the return of the actuating plate 7 requires manual return. As is clear from the above,
The lower free end 7e of the actuating plate 7 is also located closer to the stopper 11 than the line A-A'.

Reference numeral 20 indicates an interlocking plate of the present invention. In the conventional interlocking plate, the interlocking plate engages with the left side of each bimetal plate 1 to transmit the thermal curvature of the bimetal plate to the release lever, but the interlocking plate of the present invention The plate 20 has an engagement protrusion 20b with at least one bimetal plate, that is, an intermediate bimetal plate in the embodiment shown in FIG. A protrusion 20c is provided that engages with the left side surface of the end portion 7e. Reference numeral 20d designates an engaging protrusion that is pushed by the bending deformation of the bimetal plate 1.

FIG. 5 shows the thermal overcurrent relay before operation, that is, in a non-operating state, and the bimetal plate is in a position corresponding to the chain line in FIG. 4, with the interlocking plate 20 bulging to the right in the figure. The projection 20d is in contact with the left side surface of the left and right bimetals, the engagement projection 20b with the central bimetal is in contact with the right side surface of the central bimetal, and the projections 20a and 20c have also moved to the right in the figure. It is in. In this state, the release lever 3 is released, and the lower side of the operating plate 7 is A-
Located to the right of line A', the movable contact 8 is in contact with and connected to the fixed contact 10.

The operation of the present invention constructed as described above is such that when an overcurrent flows through a heater (not shown), the bimetal plate 1 is overheated from the state shown in FIG. 5 and is bent to the left in the drawing. Due to this curved deformation, the tip 1a of the left and right bimetal plates pushes the pressed portion of the interlocking plate 20 to the left, and accordingly, the release lever 3 is moved by the elastic force of the actuating plate 7 engaged with it. It is rotated clockwise around the shaft 6. Due to this rotation of the release lever 3, the contact piece 3c of the release lever pushes the protrusion 7f of the actuating plate, and the toggle mechanism reverses its operation, causing the movable contact 8 to move toward the stopper 11 as shown in FIG. Reverse and stop. The opening operation of this contact opens a switch (not shown) on the power supply side, and the overcurrent is quickly cut off, so that no current flows through the bimetal plate 1, and the bimetal plate 1 is naturally cooled and the curved deformation is restored to its normal state. . in this case,
In order to increase the return time, the return stroke is made larger than that of the normal automatic return type, and the stop position of the actuating plate 7 at the part where the movable contact 8 is fixed after the operation is reversed is as follows.
Extension line A- of the upper and lower support parts 9a and 9b of the base 9
Since it is formed so as to be oriented toward the side of the stopper 11 from A', it would normally not be able to return due to the function of the toggle mechanism. Nevertheless, according to the present invention, the engaging protrusion 2 is provided on the interlocking plate 20.
By providing 0b and 20c, the bimetal plate 1
The cooling restoring force of
, and the toggle mechanism reverses and returns to its dead center,
A movable contact 8 fixed to the lower side of an operating plate 7 is automatically returned to its original position. In this case, the tip 1a of the central bimetal plate 1 engages with the engagement protrusion 20b of the interlocking plate 20 and pushes it back, thereby executing the above operation.

In this way, the stop position of the actuating plate 7 when the operation is reversed is the extension line A-
Stopper 11 is positioned to the left of A'.
By simply changing the structure by setting the arrangement of , and improving the interlocking plate 20, it has become possible to obtain a long-term recovery time of 2 to 3 minutes or more, which was previously unachievable.

In the above, the engagement with the interlocking plate during actuation and return movement is shared between the left and right bimetals and the center bimetal, but the combination is not limited to this. There is no problem in sharing the functions of both the time and return operation, and the combination of roles can be selected arbitrarily.

[Effect of idea]

As described above, according to the present invention, the amount of thermal bending of one or more bimetal plates is transmitted to the release lever via the interlocking plate, and the actuation plate that forms the toggle mechanism by the rotation of the release lever is activated. In a thermal overcurrent relay configured to reversely drive a contact by pressing, a stopper disposed so as to stop the actuating plate after reversing the operation of the toggle mechanism at a position beyond the dead center of the toggle mechanism; The plate includes a protrusion that engages with the actuating plate and pushes the actuating plate in the return direction when the bimetal plate is restored, and a protrusion that engages with at least one bimetal plate and is pushed by the bimetal plate when the bimetal plate is restored. Because of this provision, the toggle mechanism of the actuating plate can be completely reversed and returned to its original position even though the return stroke is large, and the contact can be automatically returned to its original position. Therefore, unlike the conventional example, there is no need to use a separate reset timer, etc., the reset time is long, the operating current value can be adjusted, and the automatic reset type thermal overcurrent has a simple structure and is inexpensive. You can get a relay.

[Brief explanation of the drawing]

Fig. 1 is an internal front view showing the main parts of a conventional thermal overcurrent relay, Fig. 2 is a perspective view for explaining the actuating plate support, and Fig. 3 is a bimetal plate that restores its curvature when cooled. FIGS. 4 and 5 are internal front views showing the main parts of the present invention, showing characteristic curves and explaining the relationship between return stroke and return time. 1... Bimetal plate, 3... Release lever, 4...
... Case, 6 ... Axis, 7 ... Actuation plate, 8 ... Movable contact, 9 ... Base, 10 ... Fixed contact, 11 ...
Stopper, 20... Interlocking board.

Claims (1)

[Scope of utility model registration request] The amount of thermal bending of one or more bimetal plates is transmitted to the release lever via the interlocking plate, and the rotation of the release lever pushes the actuating plate forming the toggle mechanism to drive the contacts in reverse. In the thermal overcurrent relay, a stopper is arranged to stop the actuating plate after reversing the operation of the toggle mechanism at a position beyond the dead center of the toggle mechanism, and a stopper is arranged to engage the actuating plate in the interlocking plate. An automatic return heat type characterized by having a protrusion that pushes the operating plate in the return direction when the bimetal plate is restored, and a protrusion that engages with at least one bimetal plate and is pushed by the bimetal plate when the bimetal plate is restored. Dynamic overcurrent relay.