JP2002042595A - Oil dash pot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome the conventional problem such that part of the molten metal, crushed and molten due to a high temperature, of a ring projection erupts into a pipe in the resistance welding of an upper cover and the pipe. SOLUTION: The upper cover 31 is formed with a flange part 32 having an opposed surface 32a opposed to the flange 2a of the pipe 2, the ring projection 33 protruding from the opposed surface 32a along the circumference concentric with the flange 32, and a circumference-shaped groove part 34 formed in such a manner as to be recessed in the opposed surface 32a inside the ring projection 33. The end of the molten metal of the ring projection 33 is housed in the groove part 34 and is not torn into dust to erupt into the pipe 2 differently from a conventional manner when the ring projection 33 is molten and crushed due to current-carrying and pressure treatment in the resistance welding of the flange part 32 and the pipe 2 to the flange 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil dash pot used for a circuit breaker, an earth leakage breaker, and the like, in which a contact is tripped by an electromagnetic method.

[0002]

2. Description of the Related Art Conventionally, as an oil dash pot of this type, for example, there is an oil dash pot 1 whose longitudinal section is shown in FIG. The oil dash pot 1 comprises a pipe 2, a movable iron core 3, a spring 4, a braking oil (oil) 5,
And an upper lid 6. The pipe 2 has a hollow cylindrical shape having a flange 2a formed at an open end and a bottom 2b at a closed end, and accommodates a movable iron core 3. The spring 4 connects the movable core 3 to the bottom 2 of the pipe 2.
Pushing toward b. The pipe 2 is filled with a braking oil 5 to apply a brake to the movement of the movable iron core 3. The upper lid 6 is welded to the flange 2a of the pipe 2 and
Is blocking the open end.

As shown in the cross section of FIG. 2A, the upper cover 6 has a flange portion 7 having an opposing surface 7a facing the flange 2a of the pipe 2, and a circumference concentric with the flange portion 7. A circumferential projection (ring projection) 8 projecting from the facing surface 7a is formed. The welding between the upper lid 6 and the pipe 2 is performed by resistance welding. That is, while current is applied between the flange portion 7 and the flange 2a, the pressure is applied in a direction in which the flange portion 7 and the flange 2a come into close contact with each other, and the heat of the Joule loss causes the ring projection 8 to move as shown in FIG. The upper lid 6 and the pipe 2 are welded by being crushed and melted.

[0004]

However, in the conventional oil dash pot 1 described above, when the upper lid 6 and the pipe 2 are resistance-welded, a part of the molten metal of the ring projection 8 that has been crushed and melted at a high temperature is removed. As shown by arrows in FIG. 3 (a) to 3 (e) show the welding process of the resistance welding, in which the ring projection 8 having the trapezoidal shape shown in FIG. ), (C), and (d), the tip portion is gradually crushed, and the end portion is torn off as shown in FIG. . It was confirmed that the dust 9 had a size exceeding 0.1 mm. Part of the molten metal that has been blown off as dust 9 inside the pipe 2 hinders the smooth movement of the movable iron core 3, destabilizing the operating characteristics of circuit breakers, earth leakage breakers, etc., and sometimes cannot operate. In some cases.

In order to solve such a problem, it is conceivable to suppress the crush of the projection 8 during welding. However, if the crush is suppressed, the welding strength is reduced. Therefore, in order to maintain the quality required for the product, it is effective to increase the height of the projection 8 to secure the amount of weld metal that can be crushed and maintain the welding strength. However, the projection 8 is small, and it is difficult to perform a cutting step to make the height thin and high, so that the unit cost increases and the product cost increases.

In addition, the selection range of the resistance welding conditions under which the tip of the ring projection 8 is appropriately melted and crushed is narrow, and the maintenance of the welding conditions between the upper lid 6 and the pipe 2 has conventionally required much time and effort.

On the other hand, a gap S between the upper lid 6 and the pipe 2
(See FIG. 2 (b)), and if these are in a tight press-fit state, it is considered that there is no danger that dust will enter the pipe 2 even if dust is generated. However, with such a press-fitting structure, at the time of resistance welding, a welding current flows not only at the welding portion of the ring projection 8 but also at the press-fitting portion, and the press-fitting portion is melted to generate dust, which is mixed into the inside of the pipe. Also, depending on the degree of press-fitting of the upper lid 6 into the pipe 2, the shunt ratio of each welding current flowing between the welded portion and the press-fitted portion changes, and the welding strength becomes unstable,
In addition, a spark (firing) may occur at the press-fitting point.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems, and comprises a hollow cylindrical pipe having a flange formed at an open end and a bottom at a closed end.
The movable iron core stored in this pipe, the spring stored in the pipe that pushes this movable iron core toward the bottom of the pipe, the brake oil that fills the pipe to provide braking to the movement of the movable iron core, and the pipe flange In an oil dash pot consisting of an upper lid welded to close the open end of the pipe, the upper lid has a flange portion having an opposing surface facing the flange of the pipe, and a flange portion having a concentric circumference and a concentric circumference extending from the opposing surface. It is characterized by comprising a projecting circumferential projection (ring projection) and a circumferential groove formed in the facing surface inside the circumferential projection and recessed.

According to this configuration, at the time of resistance welding between the flange portion of the upper lid and the flange of the pipe, when the ring projection is melted and crushed by energization and pressurization, the end of the molten metal of the ring projection is formed by the ring projection. Is housed in a circumferential groove formed inside.
Therefore, even if the flange portion of the upper lid and the flange of the pipe are welded while being pressurized, the end of the molten metal in the ring projection is not broken off and jetted into the pipe as in the conventional case.

[0010]

Next, an embodiment in which an oil dash pot according to the present invention is applied to a circuit breaker 11 shown in FIG. 4 will be described.

The circuit breaker 11 is a device for interrupting the electrical connection between the power terminal 12 and the load terminal 13 by turning on and off the contact 14. The turning on and off of the contact 14 is performed by manually operating the handle 15. When an overcurrent flows between the power supply terminal 12 and the load terminal 13, the operation of the electromagnetic trip device 16 is automatically performed. . The electromagnetic trip device 16 includes a cylindrical coil 17 connected in series between the power supply side terminal 12 and the load side terminal 13.
And an oil dash pot 18 inserted into the center of the coil 17 and a tripping mechanism.

The structure of the oil dash pot 18 is the upper lid 6
Other than the above, it is shown in the same manner as the cross-sectional view of FIG. FIG. 5 (a)
FIG. 3 is a cross-sectional view illustrating a structure of an upper lid 31 used in the oil dash pot 18 according to the present embodiment. The oil dash pot 18 includes the upper lid 31 and the above-described pipe 2, movable iron core 3, spring 4, braking oil ( Oil) 5. The upper lid 31 is a flange 2 of the pipe 2.
a to close the open end of the pipe 2 as shown in FIG.

As shown in the cross section of FIG. 5A, the upper lid 31 has a facing surface 32a facing the flange 2a of the pipe 2.
, A ring projection 33 protruding from the facing surface 32a along a circumference concentric with the flange portion 32, and a circumferential groove recessed in the facing surface 32a inside the ring projection 33. 34
Are formed. The circumferential groove portion 34 is formed on the facing surface 32a.
Is formed as a step that sinks by a depth G from. As described above, welding between the upper lid 31 and the pipe 2 is performed by resistance welding, and a current is applied between the flange portion 32 and the flange 2a, and the pressure is applied in a direction in which the flange portion 32 and the flange 2a come into close contact with each other, and the joule is applied. The ring projection 33 is crushed and melted by the heat of the loss as shown in FIG. 4B, and the upper lid 31 and the pipe 2 are welded.

The trip mechanism is an oil dash pot 1
A movable iron piece 20 pivotally supported by a metal frame 19 above the metal frame 8, a latch 23 which engages with a claw 21 fixed to the movable iron piece 20 and rotates about a pin 22,
Link mechanism 2 for transmitting movement of handle 15 to arm 24
And 5.

A contact 14 is welded to the tip of the arm 24, and when the link mechanism 25 is linear as shown in the figure, the arm 24 is pushed downward to
4 is in a closed state. Electric power supplied from the power supply terminal 12 is transmitted to the arm 24, the flexible wire 26, the coil 17, and the load terminal 13 via the contact 14.

However, if the overcurrent continues to flow, the electromagnetic force generated by the coil 17 increases, and the movable iron core 3 and the upper lid 3
The magnetic flux passing through the magnetic circuit including the movable iron piece 20 and the frame 19 increases. Due to the increase of the magnetic flux, the movable core 3 moves in a direction approaching the upper cover 31 overcoming the elastic force of the spring 4 and the viscous force of the braking oil 5, and the magnetic resistance between the upper cover 31 and the movable core 3 decreases. As a result, the magnetic flux passing through the magnetic circuit further increases, and eventually the movable iron piece 20 is attracted to the upper lid 31.

When the movable iron piece 20 is drawn to the upper lid 31, the engagement between the pawl 21 and the latch 23 is released, and the latch 23
Rotates counterclockwise around the pin 22 by the elastic force of the spring 27 and collides with the link mechanism 25. Hasp 23
Collides with the link mechanism 25, the link mechanism 25, which has been arranged in a straight line, bends in a “<” shape, and the arm 24
Is moved upward by the elastic force of the conical coil spring 28. Therefore, the contact 14 is disconnected, and the electrical connection between the power supply terminal 12 and the load terminal 13 is disconnected.

FIGS. 6A to 6F are cross-sectional views showing the steps of assembling the oil dash pot 18. FIG. When assembling the oil dash pot 18, an empty pipe 2 shown in FIG. Next, as shown in FIG. 3B, the brake oil 5 is injected to a height of about 1/4 of the pipe length. Generally, silicone oil is used for the braking oil 5. Next, as shown in FIG. 3C, the movable iron core 3 is inserted into the pipe 2 and immersed in the brake oil 5. Next, the braking oil 5 is again injected into the pipe 2, and as shown in FIG.
Is filled with Next, the pipe spring 4 is inserted and placed on the shoulder of the movable iron core 3 as shown in FIG.
Next, as shown in FIG. 2F, the upper lid 31 is covered on the pipe 2 and the pipe 2 and the upper lid 31 are resistance-welded.

Oil dash pot 1 according to the present embodiment
According to the configuration of FIG. 8, at the time of resistance welding between the flange portion 32 of the upper lid 31 and the flange 2a of the pipe 2, when the ring projection 33 is melted and crushed by energization and pressurization, the end of the molten metal of the ring projection 33 is melted. Is
As shown in FIG. 5B, the ring projection 33
Is housed in a circumferential groove portion 34 formed inside. Therefore, the flange portion 32 of the upper lid 31 and the flange 2 of the pipe 2
Even if a is welded while pressurizing a, the end of the molten metal of the ring projection 33 may be ejected to the outside of the pipe 2, but it will be torn and ejected inside the pipe as in the conventional case. I will not do it.

For this reason, according to the oil dash pot 18 of the present embodiment, the smooth movement of the movable iron core 3 is hindered and the operating characteristics of a circuit breaker, a leakage breaker and the like become unstable as in the prior art. It does not make it inoperable. In addition, since the circumferential groove portion 34 is formed by a simple cutting process, the unit cost of the upper lid 31 hardly increases, and an increase in product cost can be suppressed.

Further, since the allowable range of the shape in which the tip portion of the ring projection 33 is melted and crushed is widened, the selection range of the resistance welding conditions is wider than before. For this reason, maintenance of the welding conditions between the upper lid 31 and the pipe 2 can be easily performed. Further, since it is not necessary to adopt a structure in which the upper lid 31 is press-fitted into the pipe 2, the conventional problem caused by the press-fitting structure does not occur.

[0022]

As described above, according to the present invention, when the ring projection is melted and crushed by energization and pressurization at the time of resistance welding between the flange portion of the upper lid and the pipe flange, the molten metal of the ring projection is melted. Is accommodated in a circumferential groove formed inside the ring projection. Therefore, even if the flange portion of the upper lid and the flange of the pipe are welded while being pressurized, the end of the molten metal in the ring projection is not broken off and jetted into the pipe as in the conventional case.

For this reason, according to the oil dash pot of the present invention, the smooth movement of the movable iron core is hindered, and the operating characteristics of the circuit breaker for wiring, the earth leakage breaker, and the like become unstable, and the operation becomes impossible. It does not make it possible. Also,
Since the circumferential groove is formed by a simple cutting process, the unit cost of the upper lid hardly increases, and an increase in product cost can be suppressed.

Further, since the allowable range of the shape in which the tip of the ring projection is melted and crushed is widened, the selection range of the resistance welding conditions is wider than before. Therefore, maintenance of the welding conditions between the upper lid and the pipe can be easily performed. Further, since it is not necessary to adopt a structure in which the upper lid is pressed into the pipe, the problem caused by the press-fitting structure does not occur.

[Brief description of the drawings]

FIG. 1 is a sectional view of a conventional oil dash pot.

FIG. 2A is a cross-sectional view of an upper lid used for a conventional oil dash pot, and FIG. 2B is a partially enlarged cross-sectional view showing an upper lid portion of the conventional oil dash pot.

FIG. 3 is a partially enlarged sectional view showing a conventional resistance welding process between an upper lid and a pipe.

FIG. 4 is a cross-sectional view of a circuit breaker using an oil dash pot according to an embodiment of the present invention.

5A is a sectional view of an upper lid used in an oil dash pot according to an embodiment of the present invention, and FIG. 5B is a partially enlarged view showing an upper lid portion of the oil dash pot according to an embodiment of the present invention. It is sectional drawing.

FIG. 6 is a cross-sectional view illustrating an assembly process of an oil dash pot according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 ... Pipe 2a ... Flange 2b ... Bottom 3 ... Movable iron core 4 ... Pipe spring 5 ... Brake oil 31 ... Top lid 32 ... Flange part 32a ... Opposing surface 33 ... Ring projection (circumferential projection part) 34 ... Circular groove part

Claims (1)

[Claims] 1. A hollow cylindrical pipe having a flange formed at an open end and a bottom at a closed end, a movable core accommodated in the pipe, and the pipe for pushing the movable core toward the bottom of the pipe. An oil dash pot comprising a spring stored in a pipe, a brake oil filled in the pipe to apply a brake to the movement of the movable core, and an upper lid welded to a flange of the pipe to close an open end of the pipe, The upper lid has a flange portion having a facing surface facing the flange of the pipe, a circumferential projection projecting from the facing surface along a circumference concentric with the flange portion, and a circumferential projection portion. An oil dash pot comprising: a concave groove formed in the inner facing surface.