JPS6346967B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oil dumppot type electromagnet that is incorporated into, for example, a molded circuit breaker and used as a sensor for detecting overcurrent.

Conventionally, as shown in FIG. 1, this type of oil dumppot type electromagnet uses an electromagnetic force generated by an overcurrent flowing through a coil 1 to move a plunger 3 housed in a cylinder 2 against the viscous resistance of the braking oil 4. The armature 7 was moved upward against the elasticity of the return spring 5, and the armature 7 was attracted to the pole head 8 against the elasticity of the spring 6, thereby obtaining a mechanical output, but the attraction due to leakage magnetic flux (ineffective magnetic flux) Because it does not use force, that is, solenoid suction force,
The drawback was poor high-speed response.

For this reason, the second method to improve the above drawbacks is
The structure shown in the figure was proposed. That is, the oil dumppot type electromagnet of this structure consists of a lower bent piece 9a of a yoke 9 having a U-shaped cross section, a bottomed cylinder 10, a brake oil 11, a plunger 12, a return spring 13, and a pole head 14. The oil dash pot block O'p is slidably disposed, and the plunger 12 is moved upward by an electromagnet generated by an overcurrent flowing through the coil 15 to attract the lower end of the pole head 14. Upper bent piece 9b of yoke 9
By increasing the magnetic flux flowing between the fixed iron cores 16 fixedly attached to the iron core 16, the oil dart pot block O'p is moved upward against the spring 17 elastically mounted between its lower end and the lower bending piece 9a. Mechanical output is obtained by pushing up an operating pin 18 made of a non-magnetic material and slidably penetrating the fixed iron core 16.

On the other hand, if a short-circuit current flows through the coil 15, the strong electromagnetic force generated thereby causes the oil dash pot block O'p to move upward without waiting for the plunger 12 to operate.
You can instantly obtain mechanical power by pushing up the
In this way, in this conventional type, the attraction force due to the reactive magnetic flux is applied to the tripping operation due to the structure of the oil dash pot block O'p, so the operation is slower than that of the conventional example shown in Fig. 1. The plan was to speed it up.

Therefore, P' and A' in the figure are cylinder 1
The magnetic air gap formed between the upper end of the plunger 12 and the lower end of the pole head 14 in the fixed iron core 16, and the magnetic air gap formed between the upper end of the pole head 14 and the lower end of the fixed iron core 16. It is composed of the following proportions:

In other words, if the magnetic resistance of the coil 15 and other components is ignored, the magnetic flux φ generated in the magnetic circuit of the oil dumppot will change the air gap magnetic resistance of the magnetic gaps P' and A' to R _P ', R _A '. Then, φ=Ni/R _A ′+R _P ′ N: Number of turns in the coil i: Current can be expressed. In this case, if the rated current is i ₀ and the current when the oil dash pot operates instantaneously without delaying operation is 8 times the rated current, then the plunger flows through the brake oil from 1.2 times the rated current. movement, the plunger and pole head are in close contact,
The oil dash pot block operates when R _P '≒0. In other words, the magnetic flux when the oil dumppot operates is φ _1.2 = N×1.2i ₀ /R _A ', and when it operates with a short circuit current flowing, φ ₈ =
It is expressed as N×8×i ₀ /R _A ′+R _P ′. And φ _1.2
= φ ₈ , then from the above equation, 1.2/R _A ′=8/R _A ′+R _P ′, so R _P ′/R _A ′≒5.7.

Therefore, in this type of structure, it is necessary to design the plunger so that the ratio of the magnetic resistance between the plunger and the pole head and the magnetic resistance between the pole head and the fixed iron core is about 5:1.

However, in the oil dumppot type electromagnet shown in Fig. 2, the air gap magnetic resistance formed in the magnetic circuit is a simple air gap structure, and the operating pin is made of a non-magnetic material, so the fixed iron is not used. The magnetic resistance of the air gap between the core and the pole head is large, and the magnetic resistance of the air gap between the pole head and the plunger must also be set at a ratio of approximately 1:5, resulting in a large magnetic resistance and poor magnetic efficiency. This resulted in an increase in the size of the device, and the release operation was not particularly fast.

The present invention improves these conventional drawbacks, reduces the magnetic resistance of the air gap between the fixed iron core and the pole head, and improves magnetic efficiency, thereby reducing the overall size of the device, saving windings, and reducing the size of the device. The object of the present invention is to provide an oil dumppot type electromagnet that has improved instantaneous response by improving magnetic efficiency and magnetic efficiency.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIG. 3, reference numeral 19 is a yoke made of a magnetic material with a substantially U-shaped cross section, and its lower bent piece 19a
A recess 20 and a through hole 21 communicating with the recess 20 are formed approximately in the center of the recess 20, and an oil dash pot block Op is fitted into the through hole 21 so as to be able to slide up and down, and is normally connected to the recess 20. It is biased downward by the elasticity of a spring 23 that is elastically mounted between a spring receiver 22 fixed to the lower end of the cylinder, which will be described later.

The oil dash pot block Op includes a bottomed cylindrical cylinder 24 made of a non-magnetic material, and a brake oil 25 sealed within the cylinder 24.
A plunger 26 made of a magnetic material is housed in the cylinder 24 so as to be movable up and down, and the cylinder 24
a return spring 27 that is elastically loaded inside and urges the plunger 26 downward; and a pole head 28 made of a magnetic material that seals the opening of the cylinder 24.
It has a sealed structure.

Reference numeral 29 denotes a fixed iron core made of a magnetic material fixed approximately at the center of the upper bent piece 19b of the yoke 19 , with its lower end facing the upper end surface of the pole head 28. A slide hole 30 is formed, and a small-diameter pull-out pin 31 made of a magnetic material and connected to a pull-out mechanism (not shown) slides through the slide hole 30 at its upper end. In this case, the lower end of the detachable pin 31 is integrally connected to the upper end surface of the pole head 28. In addition, 32 is located inside the yoke 19 ,
The coil is wound around a coil bobbin, and the upper end of the oil dash pot block Op is normally disposed within the hollow portion of this coil.

In the oil dart pot type electromagnet constructed in this way, when the rated current flows through the coil 32, the plunger 26 in the cylinder 24 receives the ineffective magnetic flux of the coil 32, that is, the so-called solenoid attraction force; Due to the elasticity of the return spring 27 and the viscous resistance of the brake oil 25, it cannot operate.

In the electromagnet device of the present invention constructed in this manner, if a current such as an overload current flows through the coil 32, the tripping pin 31 is made of a thin magnetic pin, so that the pole head 28 When the magnetic gap P with the plunger 26 is large and the gap magnetic resistance R _P is large, that is, when the plunger 26 is at rest or at the beginning of movement, the magnetic flux φ flowing through the magnetic circuit is small, so the tripping pin 31 is not magnetically saturated. , magnetic flux flows, so the air gap magnetic resistance R _A of the magnetic air gap A between the pole head 28 and the fixed iron core 29 becomes an extremely small value. On the other hand, as the plunger 26 moves upward and the magnetic gap P approaches zero, the gap magnetic resistance R _P
decreases, and as a result, a large amount of magnetic flux φ begins to flow.Since the cross-sectional area of the tripping pin 31 is small, when this state is reached, magnetic saturation occurs.
Thus, a suction force sufficient to attract the oil dash pot block Op toward the fixed iron core is generated between the pole head 28 and the fixed iron core 29.

For this reason, the oil dash pot block Op.
moves upward against the elasticity of the spring 23, causing the tripping pin 31 integrally connected to the upper end surface of the pole head 28 to move upward, and a desired mechanical output is obtained at the upper end of the tripping pin 31.

On the other hand, when a high overcurrent such as a short circuit current flows through the coil 32, a strong electromagnetic force is generated in the coil 32.
Since this acts on the oil dash pot block Op, the oil dash pot block Op does not have to wait for the plunger 26 to actuate and the spring 23
The mechanical force is applied to the upper end of the tripping pin 31. Therefore, in this case, a high-speed tripping operation can be achieved.

FIG. 4 shows another embodiment of the present invention, which differs from the embodiment shown in FIG. The lower end surface of the fixed iron core 29 is formed into a concave conical surface capable of receiving the pole head 28, and by increasing the opposing area of the two, the pole head 28
and the air gap magnetic resistance R _A of the fixed iron core 29 are reduced,
As a result, the magnetic efficiency is improved compared to the previous embodiments. The rest of the structure is the same as that of the embodiment shown in FIG. 3, and corresponding parts are given the same reference numerals.

As described above, the present invention has the advantage that magnetic efficiency can be improved compared to conventional devices of this type since the tripping pin for transmitting the operation of the oil dash pot block is made of a magnetic material. In addition, by reducing the magnetic resistance of the air gap between the fixed iron core and the pole head, the magnetic resistance of the air gap between the pole head and the plunger can also be reduced, making the overall device smaller and saving winding wire. Furthermore, due to the miniaturization and high magnetic efficiency, the inertia of the plunger and, by extension, the oil dash pot block is reduced, so that instantaneous response can be expected to be improved.

[Brief explanation of drawings]

1 and 2 are cross-sectional views showing a conventional example, FIG. 3 is a cross-sectional view showing one embodiment of the present invention, and FIG. 4 is a cross-sectional view showing another embodiment of the present invention. 24...Cylinder, 25...Brake oil, 26...
...Plunger, 27...Return spring, 28...Pole head, 29...Fixed iron core, 31...Removal pin, 32...Coil, Op...Oil dash pot block.

Claims (1)

[Claims] 1 A cylinder made of a non-magnetic material is filled with brake oil, a plunger made of a magnetic material, and a return spring that gives a tendency to return to the plunger, and the opening of the cylinder is sealed with a pole head made of a magnetic material. It consists of an oil dash pot block, a coil disposed around the oil dash pot block, and a fixed iron core made of a magnetic material placed facing away from the end face of the pole head. In the oil dash pot type electromagnet, the oil dash pot block operates after the plunger approaches the pole head, and in the event of a high overcurrent, the oil dash pot block operates instantly without waiting for the plunger to operate, A tripping pin that penetrates the fixed iron core and transmits the operation of the oil dash pot block is made of a magnetic material, and a lower end of the tripping pin is integrally connected to the pole head. Oil dart pot type electromagnet.