JPS6012247Y2 - proportional solenoid - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a proportional solenoid used in an electromagnetic proportional control valve or the like.

The conventional proportional solenoid shown in Fig. 1 has an excitation coil 1
When energized, the axial attraction force between the movable core 2 and the lower fixed core 3 remains constant regardless of the stroke of the movable core 2.

Therefore, the pipe portion 4 of the upper fixed core 4 that constitutes a part of the magnetic path
A and the annular wall 3 of the lower fixed iron core 3 are either left with an air gap or are joined with a non-magnetic material 5 such as a brazing material. In the former case, the tube part of the upper fixed iron core 4a and the annular wall 3a of the lower fixed iron core 3 are difficult to align and maintain.

In addition, in the latter case, not only is the manufacturing process complicated, but it is also necessary to machine the inner surfaces of the parts after joining and to apply surface treatment to prevent wear, which increases manufacturing costs. There was a problem.

Furthermore, the sliding movement of the movable core 2 in the axial direction is mainly guided by the pipe portion 4a of the upper fixed core 4, but radial attraction forces act between them in the radial direction, causing the movable core to move. Because the iron cores are tilted in either direction, the surfaces of both iron cores rub against each other, resulting in significant wear and tear, resulting in extremely short service life.

In a proportional solenoid, the movable core 2 is displaced in an analog manner due to the balance between the electromagnetic force and the load, so even slight wear, which is not a problem with an on/off solenoid, is caused by the sliding resistance between the two cores. This is because it appears as a significant change in the amount of water and has a significant impact on the above balance.

The wear between the cores is not so great in an oil-immersed solenoid due to oil lubrication, but it is particularly significant in a pneumatic proportional control valve where oil or the like does not exist between the two cores.

In view of the above, the present invention provides the above-mentioned proportional solenoid with a bearing having an inner diameter smaller than that interposed between the tube part of the upper fixed core and the annular wall of the lower fixed core, so that the sliding of the movable core is achieved only by the bearing. The movable iron core is prevented from coming into direct contact with the pipe section and the annular wall, thereby preventing shortening of the life of the proportional solenoid due to wear, and preventing the upper part from being fixed as in the conventional example. This is characterized by eliminating the need for a processing step associated with joining the tube portion of the iron core to the tubular wall of the lower fixed iron core, thereby reducing manufacturing costs.

Hereinafter, an embodiment of the present invention will be described in detail based on the drawings. In FIG. 2, 11 is a coil assembly, which includes an excitation coil 12 with a winding 12b wound around a bobbin 12a, and a magnetic frame covering the outside of the excitation coil 12. 13 integrally molded with a synthetic resin 14, into which a bearing 15 such as an impregnated bearing formed into a cylindrical shape made of a non-magnetic wear-resistant sliding material is inserted, and the bearing 15 is It is interposed between the tube portion 16a of the upper fixed core 16 and the annular wall 17a of the lower fixed core 17, which are fitted and fixed to opposite ends of the coil assembly 11 inside.

Note that, as the bearing 15, a dry bearing made of a bronze-based base metal with a solid lubricant such as graphite dispersed therein, or a ceramic material may also be used.

A movable core 19, which is attracted to the lower fixed core 17 when the coil 12 is energized, is slidably inserted into the shaft hole 18 formed inside the coil 12 by these cores, etc., and As shown in FIG. 3, the inner diameter of the bearing 15 is formed smaller than the inner diameter of the tube portion 16a and the annular wall 17a, so that the sliding movement of the movable core 19 is guided only by the bearing 15, and the movable core 19 and the tube The portion 16a and the annular wall 17a are formed in a non-contact state, that is, in a loosely inserted state through the gap 20.

The difference between the inner diameters of the tube portion 16a and the annular wall 17a of the upper and lower fixed iron cores and the inner diameter of the bearing 15 can be set to 0.1 mm or less.

Furthermore, a bushing rod 21 that opens and closes a valve seat (not shown) in the valve body is fixed to one end of the movable iron core 19, and a ring-shaped degaussing plate 22 is fixedly inserted into the rod 21. are doing.

Note that 23 is a cap on the upper surface, and a bolt (not shown) or the like inserted through the cap 23 is used to fix the proportional solenoid to the valve body.

Next, the operation of the proportional solenoid having the above configuration will be explained.

The proportional solenoid has the suction force characteristics shown in FIG. 4.

That is, when the amount of current is constant, the movable iron core 19
When the lower end surface of is within the range of t)1 shown in Fig. 2,
As the movable iron core 19 approaches the lower fixed iron core 17, the axial suction force increases, and in the range 12, the axial suction force increases as the movable iron core 19 approaches the annular wall 17 of the lower fixed iron core 17.
It remains constant regardless of the stroke due to the effect of the suction force acting between the movable iron core 19 and the lower fixed iron core 17, and in the range of ls, the suction force in the axial direction increases rapidly as the movable iron core 19 approaches the lower fixed iron core 17.

Therefore, the stroke of the movable iron core 19 within the range of ls is cut by the degaussing plate 22.

In this way, within the range of 12, the attraction force in the axial direction between the movable core 19 and the lower fixed core 17 is constant regardless of the stroke, and therefore the attraction force is proportional to the amount of current flowing through the coil 12. If the force of the return spring of the valve body in the electromagnetic proportional control valve is applied as a load on the bush rod 21 of the proportional solenoid, the flow rate, etc. can be controlled in accordance with the amount of energization.

The movable core 19 is guided by a bearing 15 with a small inner diameter, contacts only the bearing 15, and connects the pipe portion 16a and the annular wall 17a in the upper and lower fixed cores 16.17.
Since it is maintained in a non-contact state with the inner surface of the movable core 19, changes in the sliding resistance of the movable core 19 due to wear can be prevented, and the original suction force characteristics can be maintained over a long period of time.

Further, the bearing 15 is provided between the upper and lower fixed iron cores 16 and 17, and the base of the movable iron core 19 is held by the bearing 15,
However, since the area between both fixed iron cores is a part where the magnetic flux in the axial direction and the radial direction intersect, the above-mentioned bearing 1
The guiding of the movable iron core 19 by the movable iron core 19 by the movable iron core 19 is extremely effective in sliding it in the axial direction without tilting it.

In this way, according to the proportional solenoid of the present invention, bearings with smaller inner diameters are interposed between the tube portion and the annular wall of the upper and lower fixed cores inserted into the excitation coil, and the movable core In addition to being guided by bearings, the movable iron core is in a non-contact state with the pipe section and the annular wall, so that wear on them can be prevented and the desired suction force characteristics can be maintained over a long period of time. Compared to conventional examples in which the annular walls are connected by brazing with a non-magnetic material, etc., manufacturing costs can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional example, FIG. 2 is a sectional view of an embodiment of the present invention, FIG. 3 is a partially enlarged view of section A, and FIG. 4 is a diagram showing the suction force characteristics. 12... Excitation coil, 15... Bearing, 16... Upper fixed core, 16a...
Pipe part, 17...Lower fixed core, 17a...
...Annular wall, 19...Movable iron core.

Claims (1)

[Scope of utility model registration request] The tube part of the upper fixed iron core and the annular wall of the lower fixed iron core, which form part of the magnetic path, are inserted and fixed into both internal ends of the excitation coil so that they face each other via bearings with an inner diameter smaller than those. A proportional solenoid characterized in that a movable iron core, which is attracted to the lower fixed iron core when energized, is inserted into the interior of the solenoid so as to be slidably supported in the axial direction by the bearing.