JP3033897B1 - electromagnet - Google Patents

Abstract

A penetrating electromagnet generates a high attractive force near a maximum stroke, but the attractive force acting on the plunger tends to decrease with the progress of the attractive force of the plunger. Characteristics were not high. Improve this. A fixed iron core composed of a double cylinder with a coil wound around an inner cylinder, a cylindrical movable core that enters and retracts between the double cylinders, and the movable iron core is held at a retracted position when the coil is energized. An electromagnet provided with the means 40 has been developed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnet, and more particularly, to an electromagnet which generates mechanical force when energized, and in particular, generates a strong attraction force with a small electric input, and can be reduced in size and weight.

[0002]

2. Description of the Related Art The present inventor has disclosed an electromagnet which generates a strong attractive force with a small electric input and which can be reduced in size and weight (Japanese Patent Laid-Open No. 10-50518). This technology
A coil called an insertion-type electromagnet as shown in FIG. 8 , a coil having an electric wire wound around a cylindrical bobbin, and a yoke which forms a magnetic path of the coil and has axially parallel magnetic pole surfaces formed outside both end openings of the bobbin. And a plunger inserted in the hollow hole of the bobbin movably in the axial direction. In the electromagnet, one magnetic pole surface of the yoke is extended in the axial extension direction by a required length, and the plunger when the coil is not energized. An electromagnet comprising means for making the axial position of the end face orthogonal to the axis when no current is applied substantially coincide with the inner end face of the one magnetic pole face of the yoke.

[0003] This electromagnet can obtain a large initial attraction force with a small electromagnetic force, and is a small and light electromagnet which operates with a small amount of power as a highly sensitive electromagnet.

[0004]

The penetrating electromagnet according to the above proposal has a small electric force when the required stroke is relatively large as compared with a conventional electromagnet in which the magnetic pole surface of the plunger is attracted to the magnetic pole surface of the fixed iron core. A strong initial suction force is generated at the input to enable small size and light weight. However, this insertion type electromagnet generates a high attraction force near the maximum stroke, but the attraction force acting on the plunger tends to decrease as the stroke decreases due to the progress of the attraction of the plunger. The suction force characteristics were not favorable.

The inventor of the present invention has conducted various trial experiments to improve this point, and has concluded that the reduction in the attraction force accompanying the progress of the attraction of the plunger is caused by the impedance in the magnetic path of the electromagnet. .

FIG . 4 shows a schematic electric circuit . Internal resistance Ri, and a load resistor Ro and the power source coupled in series, the electromotive force and E, the power internal resistance Ri as a variable, the K is a proportional constant, also the output W value when Ro / Ri = 1 Assuming 100%, the output W corresponding to each Ro / Ri numerical value
(%) Was calculated. This is summarized in Table 1 and described. FIG. 5 shows this value in a graph. W (%)
Is the maximum value in the impedance matching state in which the condition of Ro / Ri = 1, that is, Ro = Ri is satisfied, and it is apparent that the value rapidly decreases in the range of Ro / Ri <0.5.

[0007]

[Table 1]

Here, the impedance matching in the magnetic path of the electromagnet will be discussed.

FIG . 8 is a schematic structural view of a conventional insertion type electromagnet. The coil 51 is built in the yoke 50, and the magnetic pole surfaces 52 and 53 of the yoke are formed in parallel to the axial direction.
The movable iron core 60 is held by a spring or the like at a position where one end surface 61 is deviated from one magnetic pole surface 52 of the yoke, and a portion 62 near the other end of the movable iron core 60 is axially connected to a magnetic pole surface 53 of the yoke. It is opposite in the axial direction. When the coil 51 is energized, the movable core 60 has one end surface 61 pulled by the magnetic pole surface 52 of the yoke, and moves forward against the urging force of a spring or the like. At the end of the forward movement, one end face 61 of the movable iron core is attracted to the stop end face 55 of the yoke. The magnetomotive force by energizing the coil is U, the magnetic resistance of the operating gap 63 of the plunger is Ro, the magnetic resistance of the sliding portion of the other counter electrode surface 53 is Ri (including the magnetic resistance of the yoke and the core of the plunger), and The rate of change of the magnetic energy stored in the operating gap by energizing the coil, that is, the attraction force acting on the plunger is F. If the starting force E of the electric circuit shown in FIG. 4 is replaced by the magnetomotive force U and Ri and Ro are magnetic resistances, the following equation is obtained from the similarity between the magnetic circuit shown in FIG. 8 and the electric circuit shown in FIG. Holds.

F = Ro (U / Ro + Ri) ² = KU ² / Ri If this is described in the graph of FIG. 5 , Ro / Ri = 1, that is, when the condition of Ro = Ri is satisfied, an impedance matching state is established. The value of the acting suction force F indicates the maximum value. Then, it can be understood that it rapidly decreases in the range of Ro / Ri <0.5.

That is, in the conventional insertion type electromagnet shown in FIG. 8, when the magnetomotive force U is set to a constant value, in order to generate a strong attractive force and effectively reduce the size and weight, the following two types are required. Conditions must be met.

(1) Magnetic resistance of the gap between the sliding portions of the plunger (including the magnetic resistance of the yoke and the core of the plunger) R
Set i to a very small value.

(2) The ratio of the magnetic resistance Ro of the operating gap to the magnetic resistance of the gap between the sliding portions of the plunger (including the magnetic resistance of the yoke and the core of the plunger) Ri, and the numerical value of Ro / Ri is 0.5. It is limited to a numerical value near 1.0 in the range from 2.0 to 2.0.

It is necessary to examine whether the conventional penetrating electromagnet shown in FIG . 8 has a shape that sufficiently satisfies these two conditions.

The present inventor has developed an inexpensive and high-performance electromagnet which sufficiently satisfies the above two conditions by improving the shape and configuration of the magnetic path of a conventional insertion type electromagnet based on the above findings. did. An object of the present invention is to provide such a new electromagnet.

[0016]

Means for Solving the Problems The technical means of the present invention for solving the above-mentioned problems includes an iron core wound with a coil and the core .
One end of the yoke, which is composed of a yoke arranged on the outer peripheral side of the
Is connected to the iron core and the other end of the yoke is
A fixed iron core having an interval facing the outer surface;
The inner surface of the core and the outer surface of the iron core
With an outer peripheral surface and an inner peripheral surface facing each other,
And the movable core freely, of the movable core when the coil not energized
The outer and outer peripheral surfaces do not face the inner surface of the yoke and the outer surface of the iron core.
Further comprising a means for holding the movable iron core to have retracted position is an electromagnet, characterized in. The present invention relates to a fixed coil wound coil.
Facing the fixed core and the surface in the gap provided at one end of the fixed core,
And a movable iron core that moves to a non-face-to-face position.

[0017] While a cross section perpendicular to the shaft of the fixed iron core and the movable iron core can be of any shape, preferably the iron core is cylindrical or inner cylinder, the yoke is the outer tube, the variable dynamic core is a cylindrical It is suitable. Contact Yes dynamic iron core yoke and the iron core period of such
It is preferable to provide a stop suction surface where the movable core and the fixed iron core come into close contact with each other when entering the gap, since the suction force becomes large at the rear end of the suction stroke and the stop position is stabilized.

The valve seat of the movable core as a means for holding the movable iron core to the retracted position, the switch contacts other, to be embedded in an element for stopping in position is meant a means for keeping the stable stop position. Further, the elastic force, gravity, buoyancy of the fluid, against the biasing force by the magnetic force or the like, a movable iron core fixed
If the spring force to act between the core, or when stabilizing the movable iron core to the equilibrium position by the permanent magnet attraction force is meant a means to keep the equilibrium holding position of the movable core.

A magnetic pole surface perpendicular to the axis is disposed on the cylindrical movable iron core as a stop suction surface, and by energizing the coil, the magnetic pole surface is brought into close contact with the magnetic pole surface orthogonal to the axis of the fixed iron core. The attractive force characteristics of the opposing electromagnets can be combined, and the holding force of the movable core to the fixed core can be secured.

[0020]

FIG. 1 shows an electromagnet according to an embodiment of the present invention. FIG. 1A is a cross-sectional view (AA in FIG. 1B).
1 (b) is a longitudinal sectional view (BB of FIG. 1 (a)).
FIG. 1B shows an upper half in which the movable iron core is at the retracted position, and a lower half in which the coil is energized and in an activated state. Technical means for solving the above-mentioned problems will be described with reference to a schematic structural sectional view of the cylindrical movable iron core electromagnet.

The fixed iron core 10 includes a yoke 11 forming an outer cylinder and an iron core 13 forming an inner cylinder, and a coil 20 is wound around the iron core 13 on the inner surfaces of the inner cylinder and the outer cylinder. The cylindrical movable core 3 is provided between the inner surface 12 of the yoke 11 and the outer surface 14 of the iron core 13.
0 is arranged to be able to move forward and backward. The outer peripheral surface 31 and the inner peripheral surface 32 of the movable core 30 form minute gaps with the inner surface 12 of the yoke and the outer surface 14 of the iron core, respectively. As shown in the upper half of FIG. 1B, when the movable iron core is in the retracted state, the inner surface 12 of the yoke and the outer surface of the iron core do not face the outer peripheral surface 31 and the inner peripheral surface 32 of the movable iron core. Is kept. The retracted position is a position where the outer surface and the inner surface of the movable core are not opposed to the inner surface of the yoke and the outer surface of the iron core, and the change in the electromagnet's paminance with respect to the axial displacement of the movable iron core is small. The means for holding the movable iron core at the retracted position is a spring 40 or the like.

When the coil is energized, the movable core 30 compresses the spring 40 and enters between the yoke 11 and the iron core 13 as shown in the lower half of FIG.
0 perpendicular magnetic pole face 15 and the perpendicular magnetic pole face 3 of the movable core 30
5 adsorbs and abuts. When the energization of the coil is stopped, the coil returns to its original state.

By adopting such a configuration,
The gap between the sliding portions of the plunger of the conventional insertion type electromagnet shown in FIG. 8 is reduced to zero, and the magnetic resistance of the gap is reduced to zero (however, the small magnetic resistance of the yoke and the core of the plunger remains). It is possible to set a small Ri value as compared with the magnetic resistance Ro of the iron core portion. Therefore, Ro /
It is easy to set the value of Ri to a value near 1.0 in the range of 0.5 to 2.0. Therefore, the electromagnet of the present invention always generates a stronger attractive force than the conventional insertion type electromagnet, so that the above two conditions for effectively reducing the size and weight can be satisfied. The force characteristics can be improved.

In this embodiment, an axially movable non-magnetic rod 34 is coaxially inserted into a through hole provided coaxially with the cylindrical iron core. A bearing 37 may be provided on the non-magnetic rod 34 to facilitate the movement of the movable core 30.

The rate of change of the permeance due to the displacement of the plunger in the working gap of the conventional insertion type electromagnet shown in FIG . 8 , that is, the attractive force F acting on the plunger is proportional to the radius rp of the plunger. In the cylindrical movable iron core type electromagnet of the present invention, it is clear that the sum of the radii of the inner surface and the outer surface of the illustrated cylindrical movable iron core 30 is proportional to rp ₁ + rp _2. if any, cylindrical movable iron core electromagnet of the present invention listed in Figure 1, it is clear that it is possible to generate a suction force of the double intensity as compared to the conventional insertion-type electromagnet listed in Figure 8.

As described above, the cylindrical movable core 30
A magnetic pole surface 35 perpendicular to the axis is arranged, and the coil 20 is energized to be brought into close contact with the magnetic pole surface 15 perpendicular to the axis of the fixed iron core 10 to generate an adsorption holding force between the two iron cores and fix the core. The suction holding force of the movable iron core to the iron core can be secured.

Another embodiment of the present invention will be described with reference to FIG.

This embodiment is different from the first embodiment in that a non-magnetic rod 36 is coaxially fixed to the top surface of the cylindrical core 10 and the cylindrical movable core 30 is fitted to the non-polar rod 36 outside. , Is the same as that of the embodiment shown in FIG. The example of FIG. 2 is a configuration suitable for an electromagnet having a short required stroke.

Another embodiment of the present invention will be described with reference to FIG.

According to the characteristics of the holding and holding of the fixed core 10 and the movable core 30 when the coil is energized, it is possible to select a combination of the fixed core 10 and the movable core 30 having various shapes as shown in FIG. it can. Figure 3 moving core 3 is the upper half in
0 indicates a state in which the retracted position, the lower half Ru der shows a state where the energized coil.

FIGS. 3 (a), 3 (b) and 3 (c)
The movable iron core 30 has a magnetic pole surface 33 perpendicular to the axis, and can exhibit a strong attraction force characteristic of a strong attraction and holding force. This suction force increases in the order of (a), (b), and (c). Note that FIG.
In each configuration described in (1) , description of a spring as a means for holding the movable iron core 30 at the retracted position is omitted.

In the above description, the inner and outer cylindrical surfaces of the fixed iron core and the inner and outer peripheral surfaces of the movable iron core are cylindrical surfaces, but corresponding to a required suction force characteristic curve, conical tapered surfaces that do not intersect within a required stroke range. Alternatively, a curved surface can be selected.

[0033]

The yoke 11, the coil 20 and the movable core 30 shown in FIG .
The attraction force characteristics of the insertion type electromagnet (comparative example) having the same dimensions of mm and the electromagnet of the example of the present invention were compared by the prototype. FIG. 7 is a graph showing this, with an applied voltage of 32 V,
The characteristics when the coil resistance is 150Ω are shown with the stroke length mm on the horizontal axis and the attractive force (gram) on the vertical axis. Curve 7
0 indicates the embodiment, and curve 71 indicates the attraction force characteristic of the conventional insertion type electromagnet. A similar attractive force is shown near both ends of the stroke length, but a decrease in the attractive force is seen in the insertion type electromagnet near the center of the stroke length. In the electromagnet of the present invention, the attraction force is large even in this portion. Therefore, the electromagnet of the present invention can generate a high attractive force with low power consumption, is small and lightweight,
It is clear that the structure has excellent effects such as simple structure and suitability for mass production.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of an electromagnet of an embodiment, and FIG.

FIG. 2A is a cross-sectional view of the electromagnet of the embodiment, and FIG.

FIG. 3 is a longitudinal sectional view showing a modification of the electromagnet of the embodiment.

FIG. 4 is a schematic electric circuit (magnetic circuit) diagram.

FIG. 5 shows the relationship between Ro / Ri and W (%) or F (%).
It is a graph shown.

FIG. 6 is an external view of a prototype electromagnet, (a) side view, and (b) positive.
FIG.

FIG. 7 is a graph showing suction force characteristics of an example and a comparative example.
You.

FIG. 8 is a longitudinal sectional view of a conventional insertion type electromagnet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnet 10 Fixed iron core 11 Yoke 12 Inner surface 13 Iron core 14 Outer surface 15 Magnetic pole surface 20 Coil 30 Movable iron core 31 Outer peripheral surface 32 Inner peripheral surface 33 End surface 34 Nonmagnetic rod 35 Magnetic pole surface 36 Nonmagnetic rod 37 Bearing 40 Spring 50 Yoke 51 Coil 52 , 53 Magnetic pole face 55 Stop end face 60 Moving iron core 61 One end face 62 Near other end 63 Gap 70, 71 Curve

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-360197 (JP, A) JP-A-4-192312 (JP, A) Jikai Sho 56-119607 (JP, U) (58) Survey Field (Int.Cl. ⁷ , DB name) H01F 7/16

Claims (3)

(57) [Claims] 1. An iron core on which a coil is wound and an outside of the coil
It consists of a yoke arranged on the peripheral side and one end of the yoke is
The other end of the yoke is connected to the inner surface of the yoke and the outer surface of the iron core.
And a yoke within the interval.
Face and outer face of the iron core with a small gap
A movable iron core having an outer peripheral surface and an inner peripheral surface which can move forward and backward within the interval, and an inner peripheral surface and an inner peripheral surface of the movable iron core when the coil is not energized.
Electromagnets, characterized in that the outer peripheral surface and means for holding the movable iron core to the retracted position where it does not face the outer surface of the yoke inner surface and core. 2. The electromagnet according to claim 1, wherein the core is a cylinder or a cylinder, the yoke is an outer cylinder, and the movable core is a cylinder. 3. The stationary core according to claim 1, wherein the movable core and the fixed core are provided with a stop attraction surface in which the movable core and the fixed core are in close contact with each other.
Electromagnet as described.