JPS6240708A - Plunger for solenoid - Google Patents

Abstract

PURPOSE:To obtain preferably sliding performance of a plunger and to readily manufacture the plunger by forming a plurality of recesses along the axial direction of an outer periphery, disposing thin plates made of a non-magnetic member in the respective recesses, and projecting the plates to approach the inner surface of a core. CONSTITUTION:A plurality of, such as 4 recesses 13 are formed along the axial direction on the outer periphery of a columnar base 11 made of a sintered magnetic material, thin plates 12 made of nonmagnetic material are disposed in the respective recesses 13, and the base 11 and the plates 12 are integrated. The shape and size of the plate 12 are formed at minimum in the degree that does not affect the area of passage of magnetism. The plates 12 are slightly projected from the surface of the base 11, and the projecting size is set substantially equal to the air gap size, i.e., a clearance between the plunger and a core for containing the plunger.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a plunger for a solenoid included in an on-off solenoid valve that requires high-speed response, or a proportional solenoid valve where the clearance between the plunger and the core is an important factor.

[Background of the invention]

FIG. 2 is a sectional view showing a solenoid portion provided with a conventional plunger. In this figure, l is a plunger, which is basically formed into a columnar shape. 4 is a core on which this plunger 1 can slide, 5 is a stator attached to the core 4 so as to face the plunger l, 3 is a coil wound around the core 4, and 2 is a coil outside the coil 3. The socket 6 to be arranged is fixedly attached to one end of the plunger 1 and fixed.

It is a bushing rod that can be slid inside the child 5.
:In such a solenoid, coil 3
To .

When energized, a magnetic circuit is formed by the plunger 1, stator 5, core 4, and socket 2, the plunger slides, the stator 5 and plunger 1 are attracted, and as the plunger 1 slides, the push port opens. ″′°”Mg2[19O-
F""4"+La゛*f:4 tb 3.

When the power is removed, the force of a return spring (not shown)
1-1' Therefore, plunger 1 slides, and along with this, the plunger
The i' shrod 6 slides upward in the figure, and the desired operation can be performed by sliding the bush 1 and the rod 6 in the vertical direction in the figure.
3(a) and 3(b) are explanatory diagrams showing the ideal suction state of the plunger 1, stator 5, and core 4 shown in FIG. 2, and FIG. 3 (al is a front sectional view, FIG. 3(b) is a plan sectional view, and FIGS. 3(C) and 3(d) are explanatory diagrams showing the suction state that occurs in actual operation of the plunger 1, stator 5, and core 4 shown in FIG. FIG. 3(C) is a front sectional view, and FIG. 3 (di is a plan sectional view).

In an ideal state where the core 4 and the plunger 1 are not eccentric as shown in FIG. Since there is a uniform gap portion between the core 4 and the plunger 1 over the entire circumference, the gap is equal at each portion of the entire circumference, and therefore a frictional force is generated between the core 4 and the plunger 1. Therefore, the sylanger 1 is slid by the efficient attraction force FA corresponding to the electromagnetic force of the coil 3, and the solenoid valve equipped with this solenoid has good responsiveness.

However, in actual operation, due to the mounting orientation of the solenoid valve, the plunger 1 and the core 4 come into contact at a certain part as shown in Figure 3 (C1, (d)), and the eccentricity is eccentric ife. Since the gap size between the plunger 1 and the core 4 becomes smaller, a radial force ΔF□...ΔFllr+ acts between the plunger resin and the core 4, as shown in FIG. 3 (C1), and when viewed as a whole, the As shown in Figure 3 (di), this radial force is F, and therefore, when the plunger 1 slides, a frictional force μF acts in its axial direction, and the attraction force FA′ of the plunger 1 is FA′=FA−μFR Therefore, it is difficult to utilize the electromagnetic force of the coil 3 efficiently, and the responsiveness deteriorates.

For this reason, in the past, non-magnetic brass rings were wrapped around the outer periphery of the plunger 1 at multiple locations, or bearings such as bearings were installed to suppress the eccentricity between the plunger 1 and the core 4, thereby preventing the sliding of the plunger l. It has been proposed to improve the dynamic performance, but with these conventional techniques, it is troublesome to attach the brass ring or bearing to the plunger 1, and it is also troublesome to manage the dimensions for attachment. It is difficult to manufacture and has defects that make it difficult to mass produce.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned actual situation in the prior art, and its purpose is to provide a plunger for a solenoid that can ensure good sliding performance of the plunger and is easy to manufacture.

[Summary of the invention]

In order to achieve this object, the present invention provides a container made of a sintered magnetic material that is movably accommodated in a cylindrical container core, provided with a plurality of recesses along the axial direction of the outer peripheral surface, and a plurality of recesses in the recesses. A thin plate made of a non-magnetic material is disposed on each of the cores, and the thin plate protrudes close to the inner surface of the core.

[Embodiments of the invention]

Hereinafter, the solenoid plunger of the present invention will be explained based on the drawings. FIG. 1(a) is a perspective view showing one embodiment of the present invention, and FIG. 1(bl) is an explanatory diagram showing a method of manufacturing the plunger shown in FIG.

In the embodiment shown in FIG. 1(a), a plurality of recesses 13, for example four recesses 13, are provided along the axial direction on the outer peripheral surface of a columnar base 11 made of a sintered magnetic material. A thin plate 12 made of a non-magnetic material is arranged in each of the recesses 13, and the base 11 and the thin plate 12 are integrated. Note that the shape and dimensions of the thin plate 12 are set to a minimum so as not to affect the magnetic path area. Also, thin plate 1
2 projects slightly from the surface of the base 11, and the projecting dimension is set to be approximately equal to the gap dimension, that is, the clearance between the plunger and the core in which the plunger is accommodated.

Such a plunger shown in FIG. 1 (al) is made of, for example, a mold 14 in which a hole 14a and a recessed portion 14b are formed so as to have finished dimension accuracy as shown in FIG. 1 (bl), and a thin plate made of a non-magnetic material. 12 is prepared, and the thin plate 12 is inserted into the recess 14.
The holes 14a may be filled with magnetic powder metal in a state where they are fitted into the holes 14b, and then compression molded and fired.

In the plunger configured in this way, the dimensions of the gap between the core and the surface of the base 11 are maintained as -, so the eccentricity between the core and the base 11 is suppressed, and the radial force is extremely small. Since it is small and uniform over the entire circumferential direction, there is no frictional force caused by the radial force, that is, frictional force due to adhesion between the base 11 and the core, and therefore the electromagnetic force of the coil is reduced by the sliding of the plunger. The plunger can be efficiently utilized for dynamic operation, and a solenoid valve equipped with the plunger can provide excellent response.

In addition, as it can be manufactured using a mold with finishing accuracy as shown in Figure 1 (b), it is excellent in mass production, and there is no need for post-processing or adjusting the clearance between the core and the manufacturing process is easy. be.

〔Effect of the invention〕

Since the solenoid plunger of the present invention is configured as described above, it is possible to ensure good sliding performance, and therefore, the response of the solenoid valve equipped with the plunger is improved compared to the conventional one. In addition, it is easy to manufacture and has excellent mass productivity, and therefore has the effect of lowering manufacturing costs compared to conventional methods.

[Brief explanation of the drawing]

FIG. 1(a) is a perspective view showing one embodiment of the solenoid plunger of the present invention, FIG. 1(b) is an explanatory view showing a method for manufacturing the plunger shown in FIG. 1(al), and FIG. 2 is a conventional 3 (al, (bl) are explanatory diagrams showing the ideal suction state of the plunger, stator, and core shown in FIG. 2, and FIG. 3 ( Figure 3(a) is a front cross-sectional view, Figure 3('b) is a planar cross-sectional view, and Figures 3(e) and (d) represent the suction state that occurs in actual operation of the plunger, stator, and core shown in Figure 2. In the explanatory diagrams shown, Fig. 3 fc) is a front sectional view, Fig. 3 (dl
is a plan sectional view. DESCRIPTION OF SYMBOLS 11... Base, 12... Thin plate, 13... Recessed part, 1
4a...hole, 14b...recess, 14...mold. (b)

Claims (1)

[Claims] 1. In a solenoid plunger that is slidably housed in a cylindrical container core and made of a sintered magnetic material, a plurality of recesses are provided along the axial direction of the outer peripheral surface, and each of the recesses is made of a non-magnetic material. A plunger for a solenoid, characterized in that a thin plate is arranged and the thin plate projects so as to approach the inner surface of the core.