JPS5919386Y2 - solenoid - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement in a solenoid attached to a hydraulic valve or the like.

When an alternating current or direct current is passed through the solenoid coil of a solenoid having a round or polygonal plunger-shaped movable core, the movable core of the solenoid is attracted to the fixed core, but
In general, the stroke suction force characteristic is as shown by curve a in FIG. 1, when the stroke S is large, the suction force F is small, and as the stroke becomes small, the suction force becomes large.

Stroke here refers to the distance between the movable core and the fixed core when the movable core moves.

Conventionally, in such cases, in order to increase the suction force when the stroke is large to a certain level, the suction force when the stroke is small becomes unnecessarily large, causing noise and shortening the life of the core itself. There are some drawbacks.

That is, in the conventional solenoid, as shown in FIG. 2, the magnetic path runs from the yoke 8 of the solenoid coil 7 through the guide tube 3, from the movable iron core 1 to the fixed iron core 2, and further through the guide tube 3 to the yoke 8. ing.

If the movable core 1 is now attracted to the fixed core 2, only the distance S between the end faces of the movable core, the fixed core, and the fixed core disappears, and the magnetic path and the effective cross-sectional area of the magnetic path hardly change. As the stroke becomes smaller, an excessive suction force is applied.

As a proposal related to solving this problem, for example, as described in Japanese Utility Model Application Publication No. 53-55663, the part of the movable core near the yoke is tapered to cross the gap between the yoke and the movable core. Some devices attempt to weaken the attractive force by increasing the magnetic resistance by changing the directional area.

However, since the magnetic resistance of such a structure changes, the attraction force characteristics deteriorate overall even at times other than small strokes, that is, over the entire stroke, and there are problems such as having to make the solenoid larger or smaller. there were.

The purpose of this invention is to solve the above problems and provide a solenoid that suppresses unnecessary excessive suction force only when the stroke is small.

Therefore, in the present invention, a fixed core, a movable core, a guide tube that surrounds the movable core in an axially movable and oil-tight manner, has one end fixed to the fixed core and the other end closed with a plug, In an oil-immersed solenoid that includes a coil and a yoke that are arranged outside the guide tube and excite a fixed iron core and a movable iron core, the bottom surface of the recessed portion A solenoid that has a concave part on the same plane as the inner wall of the yoke on the end face of the movable iron core opposite to the fixed iron core, with the opening facing outward, reducing the effective cross-sectional area of the magnetic path that passes near the end faces of the yoke and the fixed iron core. That is.

With this configuration, the magnetic path passes through the thin part of the concave portion of the movable core only at the small interval S1, so the effective cross-sectional area of the magnetic path is reduced and excessive attraction force is suppressed. While maintaining sufficient suction force for the solenoid to do the required effective work in S1, unnecessary excessive suction force is suppressed between the small interval S1, and the stroke range other than the small interval S□ salt is accurately maintained as before. Same as the suction force characteristics of the solenoid,
This provides a solenoid that does not deteriorate the effective suction force characteristics of the solenoid.

In a preferred embodiment, an inward protrusion provided on a plug, which is a lid member of the guide tube, is fitted into the recess;
This allows the axial length of the plug to protrude inwardly toward the recess, instead of outwards, using the normally internal push pins, etc., thereby shortening the axial length of the plug from the end of the guide tube. The solenoid can be made shorter.

Next, the embodiment of this invention will be explained with reference to the drawings.
In the figure, a fixed core 2 is fixed to a valve body by a threaded portion 11, and a movable core 1 is inserted into a gynod tube 3 fixed to the fixed core 2 at a welded portion 6 so as to be movable in the axial direction.

A plug 4 is fixed to the guide tube 3 at a welded portion 5, and a bushing pin 12 is inserted through the plug 4.

9 is a pin inserted into the through hole 13 of the fixed iron core 2.

A coil 7 and a yoke 8 are provided outside the fixed core 2 and guide tube 3.

A recess 14 is provided on the end surface of the movable core 1 opposite to the fixed core 2.

Now, the stroke is an arbitrary small interval S between the movable core and the fixed core.
If the suction force at a point smaller than 0 is to be prevented from increasing beyond the necessary suction force, the recess 1 of the movable core at a position where the distance between the movable core and the fixed core is Sl.
The bottom surface 15 of the yoke 4 is made to be substantially on the same plane as the inner wall 16 of the yoke 8.

In FIG. 3, the movable iron core 1 is located on the outside (on the right side in the drawing) of the position S1 described above by L.

The plug 4 is provided with a cylindrical protrusion 17 inwardly, and this protrusion 17 is fitted into the four parts 14 of the movable iron core 1.

When inserting the bushing pin 12, which requires a long axial length, into the plug 4, it is normally made to protrude outward from the end of the guide tube 3, but here, on the contrary, it is made to protrude inward from the end of the guide tube 3. By providing a protrusion 17 on the plug 4 so that the plug 4 protrudes, and by providing a deep recess 14 on the movable core 1 and fitting the solenoid into the deep recess 14, the length of the solenoid can be shortened. Compared to a solenoid, it has the same suction power but can be made shorter and smaller.

Note that the recess 14 needs to be deep; for example, even in the movable core of the conventional solenoid shown in FIG. Since there is only a depth, even when the movable core is attracted and strokes, the effective cross-sectional area of the magnetic path changes very little, and the change in the effective cross-sectional area of the magnetic path is very small. It does not affect the suction power.

In this design, when the stroke of the movable core is large, the magnetic flux density of the magnetic path is low, so the wall thickness of the recess 14 of the movable core at the part where the movable core and the yoke face each other may be thin, and since the stroke is large, the recess Since the position of the bottom surface 15 of the yoke is located outside the inner wall 16 of the yoke and L>0, there is almost no change in the suction force depending on the presence or absence of the recess 14.

Now, by passing AC or DC current through the coil, move the movable iron core 1.
strokes, and the distance between the fixed core and the fixed core is an arbitrary small distance S.
When the stroke reaches the point where 81 is reached, 1=0, and when the stroke is further made, L<0. The cross-sectional area of the path is narrowed, and the suction force becomes smaller than when the recess 14 is not provided.

The curved line in FIG. 1 shows the suction force and stroke characteristics of this invention.

By arbitrarily changing the depth and hole diameter of the recess 14, it is possible to prevent the suction force from becoming larger than necessary at a point where the stroke is smaller than the small interval S1.

In addition, by arbitrarily selecting the cross-sectional shape of the recess 14 such as a curved shape, a tapered shape, a stepped shape, etc., the suction force near the suction part (part A) can be made higher than necessary as shown in FIG. It is also possible to obtain a solenoid having so-called horizontal suction force characteristics, in which the suction force is constant with respect to the stroke near the A section.

This idea is based on the idea that, as mentioned above, at a position where the distance between the movable core and the fixed core is an arbitrary small distance S1, a magnetic path that substantially passes through the yoke and the movable core is created by creating a recess or a magnetic flux leakage portion at the end of the movable core. Since we have provided a means to reduce the effective cross-sectional area,
It is possible to achieve excellent effects such as preventing the suction force from becoming larger than necessary during a small stroke, extending the life of the solenoid, reducing noise generation, and making it possible to downsize the solenoid itself.

Note that this invention can be applied whether the current flowing through the coil is alternating current or direct current.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the suction force/stroke characteristics of a solenoid, where a shows a conventional solenoid, b shows a solenoid of this invention, Fig. 2 is a vertical cross-sectional view of a conventional solenoid, and Fig. 3 shows an embodiment of this invention. A vertical cross-sectional view is shown. 1...Movable iron core, 2...Fixed iron core, 3
...Guide tube, 4...Plug,
7... Coil, 8... Yoke, 14.
...Concavity, 15...Bottom, 16...
...Inner wall, 17...Protrusion, So...
Small interval.

Claims (2)

[Scope of utility model registration request] (1) A fixed core, a movable core, a guide tube that oil-tightly surrounds the movable core so that it can move outward, has one end fixed to the fixed core and the other end closed with a plug, and is placed outside the guide tube. In an oil-immersed solenoid including a coil and a yoke that excite a fixed core and a movable core, at a position where the distance between the movable core and the fixed core is an arbitrary small distance S1, the bottom surface of the recess is approximately the same as the inner wall of the yoke. A solenoid in which a concave portion on the same plane is provided on the end face of the movable core opposite to the fixed core with the opening facing outward, reducing the effective cross-sectional area of the magnetic path passing near the end face of the yoke and the fixed core. (2) In the recess provided on the end face of the movable core opposite to the fixed core,
The solenoid according to claim 1, wherein the solenoid is fitted with an inwardly protruding portion provided on the plug.