JP2999721B2 - electromagnet - Google Patents

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 more particularly to an electromagnet which is operated by a small electric input and which can be reduced in size and weight.

[0002]

2. Description of the Related Art Conventionally, as an electromagnet utilizing a linear motion of a plunger inserted into a bobbin of a coil by energizing the coil, as shown in the schematic structural diagrams of FIGS.
(A) flat plunger type, (b) conical plunger type,
There are (c) a truncated pyramid plunger type, (d) a taper plunger type, and (e) a leakage magnetic flux (leakage) type.

Each of these plunger-type electromagnets is slidably inserted in a bobbin axial direction in a bobbin axial hole through a coil 1 in which an electric wire is wound around a cylindrical bobbin, a yoke 2 surrounding an outer portion of the coil 1. And a fixed magnetic pole surface 4 that attracts the plunger 3 when the coil 1 is energized, and exhibits the following attractive force characteristics due to differences in the shapes of the respective magnetic pole surfaces.

(A) Planar plunger type A planar plunger type electromagnet includes a coil 1, a yoke 2, and a plunger 3, as shown in FIG. 7, and one of the yokes has a magnetic pole surface 4 facing the end face of the plunger 3. When the coil is energized, the plunger 3 is attracted to and absorbed by the magnetic pole surface 4. The mechanical force F acting on the plunger 3 of the electromagnet is such that the magnetomotive force by energizing the coil is U, the vermance of the electromagnet magnetic path is P, and the dimension of the operating gap of the electromagnet is x, and the magnetic saturation of the magnetic path of the electromagnet is ignored. For example, it is represented by the following equation.

F = (１ ／) · U ² · dP / dx (1) The electromagnetic attraction force P of the planar plunger type shown in FIG. 7 is obtained by setting the radius of the cylindrical plunger to r _p and the magnetic permeability of the working gap to R _p . If μ,
_P = μπr _p ² / x, because it is ^{_{dP / dx = -μπr p 2 /}} x 2, equation (1) can be represented by the following equation. ^{F = (1/2) · U 2} · μπ (r p / x) 2 ...... (2) i.e., flat plunger-type electromagnet is large area of numbers r _p / x, in other words, the radius r _p of the plunger When the required operation gap x is large and small, a large suction force can be obtained, which is effective.

(B) Conical Plunger Type The conical plunger type electromagnet shown in FIG. 8 is a conical cavity having the magnetic pole surface 4 of the electromagnet of FIG. 7 inclined at an angle θ with respect to a plane perpendicular to the axis of the plunger 3. A plunger 3 having a conical end face fitted coaxially facing the cavity,
The magnetic attraction force of the flat plunger type is improved by increasing the magnetic pole surface.

In the conical plunger type electromagnet having the same magnetic path permeance as that of the above-mentioned flat plunger type, the electromagnetic attraction force F of the flat plunger type is F (cos
θ) ² , but the operating gap length x can be increased by a factor of 1 / (cos θ) ^{2 in} the case of the planar plunger type. (C) Truncated cone plunger type FIG. 9 shows a truncated cone plunger type electromagnet. This electromagnet is a conical plunger deformation type electromagnet which is adopted when the numerical value of the angle θ of the conical plunger type electromagnet of FIG. 8 is selected to be small. As a measure for preventing magnetic saturation occurring in a narrow portion of the magnetic path of the iron core at the apex of the cone at the bottom of the conical cavity forming the fixed magnetic pole surface 4 in FIG. 8, the operating gap is formed in the shape of a truncated cone shown in the figure. I do. In this case, an increase in the diameter of the plunger having the dimension d shown in the drawing cannot be avoided.

(D) Taper Plunger Type In the taper plunger type electromagnet shown in FIG. 10, the ends of the yoke 2 are located outside the two openings of the bobbin of the coil 1 and each end surface has an opening larger than the hollow hole of the bobbin. The inner surface of one of the openings is a fixed magnetic pole surface 4 and the end of the plunger 3 facing the fixed magnetic pole surface 4 is formed in a tapered shape. Therefore, the above (a) and (b)
Each of the plunger types shown in (c) differs in the arrangement and shape of the fixed magnetic pole surface, and exhibits the following attractive force characteristics.

That is, referring to FIG. 10, the average radius of the tapered surface of the plunger is r _p , the axial length of the tip of plunger 3 inserted into the hollow fixed magnetic pole is x ′, and plunger 3
Assuming that the average dimension of the gap between the tapered surface and the fixed magnetic pole surface is δ and the magnetic permeability of the operating gap is μ, the permeance P of the operating gap is P = 2μπ (r
_p + 0.5δ) x ′ / δ, and dP / dx ′ = 2μπ
Since (r _p + 0.5δ) / δ, the taper plunger-type electromagnetic attractive force F is approximately expressed by the following equation (1) assuming that the taper inclination angle is small. Can be.

F = (１ ／) · U ² · dP / dx ′ = U ² · μπ (r _p + 0.5δ) / δ (3) where the above equation (3) and the above-mentioned plane plunger type are used. By comparing the above equations (2) indicating the electromagnetic attraction force of the electromagnets (conical or frustoconical types are similar) and examining the required stroke length s of each electromagnet, the relation of s = x in the above equation (2) is as follows. In the above equation (3), the required stroke length s of the tapered plunger type electromagnet is not related to the required stroke length s of the electromagnet and the axial length x ′ of the tip of the plunger inserted into the hollow fixed magnetic pole. Is determined by the design value of the axial length of the hollow fixed magnetic pole surface 4, the dimension δ of the gap between the tapered tip of the plunger 3 and the fixed magnetic pole surface, and the inclination angle θ of the taper.

Accordingly, the tapered plunger-type electromagnet, in order to increase the required stroke length s is a yoke member 2 thick forming the fixed magnetic pole surface 4, the iron core of the plunger 3 from the radius r _p of the tapered tip It is necessary to employ a large-diameter magnetic body, and there is a disadvantage that the shape of the electromagnet itself increases and the operating performance decreases. (E) Leakage Flux (Leakage) Type FIG. 11 shows a schematic structural diagram of a leakage flux (leakage) type electromagnet. This type of electromagnet is a leakage magnetic field (leakage) type electromagnet using an electromagnetic force acting between the leakage magnetic flux from the plunger 3 and the current flowing through the coil 1 because the configuration of the iron core magnetic path is insufficient. The configuration of the electromagnet of FIG. 11 is similar to the above-described taper plunger type, but since the distal end surface of the plunger 3 faces the fixed magnetic pole surface 4 with a large separation distance, the configuration of the electromagnet from the distal end surface of the plunger 3 is large. Since the leakage magnetic flux passes through a coil having a large magnetic resistance, it is not possible to effectively generate a magnetic flux due to the magnetomotive force generated when the coil is energized. Therefore, the leakage magnet type electromagnet is limited to applications where the required attraction force of the electromagnet is small and the required stroke is relatively large.

As a proposal for improving a leakage magnetic flux type electromagnet, a "solenoid" is proposed in Japanese Patent Application Laid-Open No. 53-135456. This proposal is characterized in that the position of the maximum attraction force acting on the plunger can be arbitrarily obtained, but the shape of the exciting coil becomes complicated due to the magnetic material projecting a predetermined distance inward of the yoke, and The required volume of the part is reduced, which does not necessarily contribute to downsizing of the solenoid.

[0013]

SUMMARY OF THE INVENTION The present invention has developed an electromagnet which cannot be obtained by the above-mentioned prior art, and enables high-sensitivity operation with a smaller amount of electric power at a required attraction force and stroke. It is an object of the present invention to provide an electromagnet having a lightweight shape and a simple configuration. Another object of the present invention is to provide an electromagnet in which a change in the attraction force accompanying the movement of the plunger is adjusted to a desired change.

Further, the present invention provides a high-sensitivity electromagnet which is suitably balanced at the neutral position.

[0015]

This onset Akira [SUMMARY OF] includes a coil wound around the wire to the tubular bobbin, a yoke to form a magnetic path of the coil to form an axis parallel pole faces outward openings at both ends of the bobbin,
An electromagnet comprising a plunger movably inserted in the hollow direction of the bobbin in the axial direction, wherein one of the pole faces of the yoke extends in the axial extension direction, and the shaft at the time of non-energization of the axis orthogonal end face of the plunger. The present invention is applied to an electromagnet provided with means for making a direction position substantially coincide with an inner end face of the one pole face of the yoke. The yoke and its open magnetic pole surface are preferably cylindrical in cross section, but may be arc, square, or any other shape in cross section.

Here, as a specific means for stably arranging the position of the plunger in the hollow hole of the bobbin when the coil 1 is not energized at the above designated position, a valve or other member which stably stops at a fixed position is used. When it is used in a built-in state, it is adjusted to the stable stop position. When it is used in a member having no restraint position, another position holding means is used. In other words, the means for making the axial position of the end face orthogonal to the axis of the plunger in the non-energized state substantially coincide with the inner end face of one magnetic pole face of the yoke is the positioning means with the application target device, the biasing means of the plunger, and the balance of the plunger. It is preferable to use one or more means selected from the group consisting of means. Examples of the means for positioning with respect to the application target device include a valve seat, a stopper, a push button, a relay, a contact, a position setting means of a switch device or a latching device, and the like. As the biasing means of the plunger, for example, gravity, balance weight, elastic spring force, fluid pressure,
Alternatively, there is an urging means using rubber elastic force or the like. The plunger balancing means includes, for example, a means for applying a floating force of a fluid and an electromagnetic force. Of these various means,
One or more suitable means may be used. For example, a spring force acting between the yoke side of the electromagnet and the plunger, or a magnetic force by a permanent magnet or the like is employed.

The technical means characterized by the present invention is the above-mentioned electromagnetic means.
The stone is characterized in that the plunger has the same cross-section as the entire length, and the axis-parallel magnetic pole surface extending in the axial extension direction is a surface whose cross-section changes in the axial direction. This cross section change can be given a regular cross section change according to the purpose. As this cross-sectional change, for example, a conical shape or a bell-mouth shape can be adopted. More specifically, the bellmouth shape is characterized by a regular cross-sectional change selected from the group of an arc envelope shape, a parabolic envelope shape, a hyperbolic envelope shape, and a higher-order curve envelope shape according to the purpose. A certain suction force characteristic can be exhibited.

Further, in the electromagnet having the above structure,
One pole face is fixed to the yoke, and the other pole face is interposed with a permanent magnet facing the axis-parallel side face of the plunger via a minute gap. This permanent magnet divides the magnetic flux generated by the magnetomotive force of the permanent magnet at a certain ratio into each gap between the pair of openings formed in the yoke and the axially parallel side surface of the plunger. By adjusting the gaps, the split ratio can be adjusted, and the plunger 3 stops at a position where the attractive force of the permanent magnet and the urging force of a spring or the like are balanced. In addition, by energizing the coil, the magnetic flux by energizing the coil, the magnetic flux of the permanent magnet, and the magnetic flux of the permanent magnet are superimposed or canceled to generate a large attractive force on the magnetic flux superimposed side,
Higher sensitivity than electromagnet without permanent magnet.

It is preferable to provide a magnetic pole surface perpendicular to the axis facing the end of the plunger at the axially extending end of one of the magnetic pole surfaces of the yoke because an electromagnet having characteristics of a flat plunger type electromagnet can be obtained.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation of the electromagnet shown in FIG. 1 will be described in comparison with the flat plunger type electromagnet shown in FIG. FIG. 1 is a schematic configuration diagram showing the configuration of an electromagnet to which the present invention is applied , and FIG. 2 is a partially enlarged view thereof. In the figure,
A yoke 2 is provided which surrounds a coil 1 in which an electric wire is wound around a cylindrical bobbin and which has an opening at a portion facing both ends of the bobbin. The plunger 3 slides along a parallel side surface in the hollow hole of the bobbin, and is inserted through the yoke 2 and the opening gap 7. One of the openings of the yoke 2 projects cylindrically outside the yoke, and a fixed magnetic pole surface 4 is formed on the inner surface of the cavity which is coaxial with the opening. When the coil 1 is not energized, the yoke inner side surface 5 of the hollow fixed magnetic pole surface 4 and the end surface 6 of the plunger 3 on the fixed magnetic pole surface side are stably arranged at positions substantially coincident with each other in the plunger axial direction. ing. The energization of the coil 1 causes the hollow fixed magnetic pole surface 4 to attract the plunger 3.

The gap 7 sets the magnetic flux density in the gap between the plunger 3 and the hollow fixed magnetic pole surface 4 to a desired value due to the magnetomotive force of energization of the coil 1 during the attraction process of the plunger 3 to generate a required attraction force F. And a nonmagnetic gap having a predetermined magnetic resistance inserted in series with the magnetomotive force of the electromagnet so as to approach the substantially saturated value of the electromagnet core at the end of the attraction of the plunger 3. The position where the nonmagnetic material gap is inserted in series is
It is also used as a gap arranged to avoid mechanical wear between the plunger 3 and the plunger 3 and is arranged at the position of the gap 7 shown in the figure.

Next, the significance and means of stably disposing the end face 6 of the plunger 3 at a position substantially coincident with the inner end of the pole face of the yoke in the axial direction of the plunger will be described. As shown in FIG. 2, the yoke inner side surface 5 of the hollow fixed magnetic pole surface 4,
When the end surface 6 of the plunger 3 on the side of the fixed magnetic pole surface is substantially in the axial direction, the hollow fixed magnetic pole surface 4 of the yoke 2
The strength of the magnetic field generated between the end face 6 of the plunger 3 and the end face 6 of the plunger 3 is slightly smaller than the end face 6 of the illustrated plunger 3 by the size of the gap 7b, and is indicated by a dotted line 6a separated in the right direction as viewed in the figure.
If the size of the illustrated gap 7b is very small even if it is moved to the position of, the change in the magnetic field is small, and there is no practical difference in the attractive force between the two. Therefore, the substantially coincidence means the end face 6 of the plunger 3.
However, in consideration of mechanical tolerances, the end face 6 in FIG. 2 may be located at the position of the end face 6a, or may be located within a range near this position. It should be noted that specific means for stably arranging at this position can be variously determined in relation to the target device using the electromagnet, and is not shown between the fixed portion on the yoke 2 side and the plunger 3. A mechanism is employed in which a spring or a permanent magnet or the like is disposed to apply a spring resistance or a magnetic force to the plunger 3 to stably hold the position of the plunger 3.

The relationship between the operating stroke of the plunger 3 and the suction force is illustrated in the operating characteristic curve diagram of FIG. FIG.
, The horizontal axis represents the stroke s and the vertical axis represents the suction force F.
The zero point of the stroke is the position of the inner end face 5 of the yoke 2 in FIG. 2, and the value of the stroke s (the length taken to the left from the zero point in FIG. 6) is the hollow fixed magnetic pole face 4 of the yoke 2.
In the axial direction.

A curve A shown in FIG. 6 has the same configuration as that of the first invention in which the dimension δ of the gap 7 between the tip of the plunger and the fixed magnetic pole surface is the same over the entire stroke range. An operating characteristic curve of an electromagnet whose direction length is short and whose magnetic flux density of the electromagnet magnetic path due to energization of the coil 1 approaches the saturation magnetic flux density of the iron core and whose change in permeance P is small during the attraction and movement process of the plunger 3 is shown. The attractive force F of the electromagnet acting on the plunger is applied to the inner surface 5 of the yoke of the hollow fixed magnetic pole surface 4 and the end surface 6 of the plunger 3 on the fixed magnetic pole surface side.
DOO is, position one value in the axial direction, i.e., stroke is the maximum attraction force in terms of zero rapidly attraction force according to the plunger 3 is moved to the left decreases the suction at the location of the stroke s ₁ The force is zero.

The curve B shown in the figure has the same structure as that of the above-mentioned electromagnet, but the required axial length of the fixed magnetic pole surface 4 is increased.
A first invention which has a gap size of the gap 7 for limiting the magnetic flux density of the fixed magnetic pole surface 4 to a predetermined value equal to or less than the magnetic saturation value of the iron core, and allows a required change in the pamiance P through the suction and movement process of the plunger 3. 5 is an operating characteristic curve of the electromagnet of FIG.
Therefore, the electromagnet of the present invention can generate a larger initial attractive force than the above-described prior art electromagnet, and implements a measure to increase the change of the paamiance P, and for example, implements B As in the case of the characteristic of the curve, it has the effect of increasing the required stroke of the electromagnet.

The electromagnet of the present invention can obtain a large initial attraction force with a small electromagnetic force, and is a small and lightweight electromagnet which operates with a small amount of electric power as a highly sensitive electromagnet. Therefore, it is apparent that not only the structure but also the suction force characteristics are different from the conventional leakage type which exerts a substantially flat suction force in a large stroke range. Here, the characteristics of the cross-sectional dimensions of the plunger of the electromagnet of the present invention will be described.

The effective work of the electromagnet is the product of the initial attractive force and the stroke length. A conventional electromagnet with a constant excitation ampere turn and a required stroke length can achieve maximum useful work at some suitable working gap cross-sectional area or at the optimum magnetic flux density of the working gap. That is, in order for the conventional electromagnet described in FIG. 7 to perform the maximum effective work in the same exciting ampere turn, each of the conventional electromagnets requires a plunger having an optimum sectional area corresponding to a required stroke length. It is clear from equation (2).

However, the present inventor has proposed that the electromagnet of the present invention
As shown in the above formula (3), the plunger disconnection which achieves the same effective work with a small cross-sectional area as compared with the above-mentioned conventional electromagnet by only setting the dimensions of the gap 7 irrespective of the required stroke. It has been found that by setting the area, it is possible to provide a small and lightweight electromagnet that can be driven with a small amount of electric power as compared with a conventional electromagnet, for example, a flat plunger type electromagnet shown in FIG.

The above findings can be concretely understood from the following table which compares various design values of the conventional flat plunger type electromagnet designed and manufactured with the same attractive force and stroke length with the electromagnet of the present invention. That is, the electromagnet of the present invention provides an electromagnet which can be driven with low power, has a small coil shape, and uses a small amount of copper, by employing a plunger having a smaller radius than a conventional planar plunger type electromagnet. it can.

[0030]

[Table 1]

Next, referring to FIG. 3 , in order to improve the characteristics of the electromagnet in response to another request, the initial attractive force is slightly reduced, and the characteristics are improved against the urging force of the spring against a long stroke. In some cases, it is desirable to obtain good operating characteristics. Although such one of apertures to project into the cylindrical yoke outside to request, electromagnetic forming a cavity inner surface axially parallel
Instead of the fixed pole face 4 of the stone , the dimension of the gap 7 between the fixed pole face 4 and the plunger 3 is changed to a shape that changes according to the suction movement of the plunger 2. For example, the illustrated gap 7
By sequentially decreasing the gap from a to gap 7,
It is possible to generate a desired permeance change rate. By selecting and setting the shape of the hollow cylindrical inner side surface 4a of this electromagnet, it is possible to improve the attraction force characteristics relating to the operation stroke of the plunger 3.

The electromagnet shown in FIG. 3 is obtained by changing the shape of the hollow fixed magnetic pole surface 4 of the yoke 2 in a bell mouth shape in the axial direction. Unlike the above-mentioned conventional taper plunger type, it does not require precise cutting of the taper surface of the plunger, and not only enables inexpensive mass production of the fixed magnetic pole surface by press working, but also the characteristics shown in FIG. The curve B can obtain a flat operating characteristic as shown in the curve C with the same outer dimensions and the ampere turn, and can effectively cope with a demand for a high sensitivity, small and light weight electromagnet with a large required stroke. It is.

Next, a description of the technical means of the present onset Akira shown in Figure 4. An electromagnet having a configuration in which the invention of the electromagnetic actuator disclosed in Japanese Patent Publication No. 7-52690 is applied to the electromagnet. That is, in the electromagnet having the above structure, one pole face of the permanent magnet 9 is fixed to the yoke 2, and the other pole face of the permanent magnet 9 is opposed to the axially parallel side face of the plunger 3 via a minute gap. A configuration in which the magnetic flux generated by the magnetomotive force of the permanent magnet 9 is diverted into the illustrated Φ _ma and Φ _mb in the gap between the yoke 2 and the axially parallel side surface of the plunger 3 in the pair of openings formed in the yoke 2. It is. Here, the upper half of the figure shows the position of the plunger 3 when the coil 1 is not energized, and the lower half shows the position of the plunger 3 when the coil 1 is energized.

This embodiment is of the insertion plunger type.
Therefore, compared to the conventional flat plunger type, the magnetic force on the suction side
Qi resistance R_Two Becomes a very small value, and both ends of the plunger 3
For adjusting the shape and size of the pole face of the gap between the openings of
Therefore, each magnetic resistance R ₁ And R_Two Is easy to adjust
Yes, the best to show the power saving and high sensitivity operation characteristics of electromagnet
A desirable condition is R₁ / (R₁ + R_Two ) ≒ 0.5 and
Conditions can be easily satisfied.

Next, the embodiment shown in FIG. 5 will be described. In this embodiment, a plate-like lid 8 made of a magnetic material is provided at the tip of the hollow magnetic pole surface 4 of the yoke 2 or the conical magnetic pole surface 4a. The conical pole face 4a is an example of the pole face whose cross section changes in the axial direction described above. As shown by the curve D in FIG. 6, the characteristic curve of the conventional electromagnet shown in FIG. 7 is such that the stroke S is zero, that is, the suction force at the beginning of suction is extremely small. However, it has a remarkably large suction force near the stroke end. As shown in Table 1 above, the size of the plunger for obtaining the same attractive force is remarkably large in the parallel-plane type electromagnet, and when the electromagnet is of the same size and has the same ampere-turn, it is significantly smaller than the embodiment of the present invention. A small initial suction force results. In a flow control valve or the like having a long stroke and requiring the spring to be compressed over the long stroke, the first or second invention of the present invention in which the suction force is theoretically zero near the stroke end Need to be improved.

For applications requiring a substantially constant attractive force within the range of an operation stroke, such as an electromagnetic valve and an electromagnetic brake mechanism, if the above-described electromagnet of the related art is employed, an increase in drive power and an increase in the size of the device can be achieved. The use of the electromagnet of the present invention, in which attraction force approaches zero near the end of the operation stroke as described above, leads to an increase in size, and it is inevitable that the operation will be unstable. And

In the embodiment shown in FIG. 5, a lid 8 made of a magnetic material is provided. By arranging the lid 8 fixedly at the tip of the yoke 2 as shown in FIG. 5, the operation characteristic curve shown in FIG. 6 has a characteristic almost following the characteristic curve C in a small stroke region, and is close to the stroke end. In this case, the characteristic follows the characteristic curve D, and in the middle stroke region, the characteristic becomes like a curve E. This attractive force operation characteristic can be effectively used for operation of an electromagnetic valve, an electromagnetic brake mechanism, etc.
It is suitable for applications such as position operation or for improving the attracting coercive force of a latching operation electromagnet using a permanent magnet.

Each of the embodiments of the present invention shown in FIGS. 1 to 5 is an electromagnet having excellent characteristics as described above. However, these are merely examples, and the present invention is limited to the above-described embodiment. The present invention is not limited to this, and can be appropriately modified and implemented within a range that does not change the gist of the present invention.

[0039]

The present invention exhibits the following excellent effects. (1) It is power-saving, and can operate with high sensitivity even with a minute power supply capacity such as a battery power supply. (2) A small and lightweight electromagnet can be provided. (3) The structure is simple and robust, and the processing and assembly of parts is easy and suitable for mass production. (4) Quiet driving of the plunger is possible, and no noise is generated during operation. (5) Latching characteristics utilizing permanent magnets are exhibited.

[Brief description of the drawings]

1 is a longitudinal sectional view of the electromagnets.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a partial enlarged view of the real施例.

FIG. 4 is a longitudinal sectional view of another embodiment.

FIG. 5 is a longitudinal sectional view of another embodiment.

FIG. 6 is a graph showing a relationship between a stroke and a suction force according to the embodiment.

FIG. 7 is a longitudinal sectional view of a conventional electromagnet.

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

FIG. 9 is a longitudinal sectional view of a conventional electromagnet.

FIG. 10 is a longitudinal sectional view of a conventional electromagnet.

FIG. 11 is a longitudinal sectional view of a conventional electromagnet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Coil 2 Yoke 3 Plunger 4, 4a Magnetic pole surface 5 Axis orthogonal end face (of yoke) 6, 6a Axis orthogonal end face (of plunger) 7, 7a, 7b Gap 8 Lid 9 Permanent magnet

Claims (4)

(57) [Claims] 1. A coil (1) in which an electric wire is wound around a cylindrical bobbin, and a yoke forming a magnetic path of the coil (1) and forming an axially parallel magnetic pole face (4) outside both ends of the bobbin. and (2), Ri Do from the plunger (3) which is inserted movably in the axial direction into the hollow hole of said bobbin, said yoke (2)
One of the pole faces (4) is extended by a required length in the axial extension direction, and the axial position of the plunger perpendicular to the shaft (6) when the coil (1) is not energized is determined by the axial position when the energization is not performed. (2) means for substantially matching the inner end face (5) of the one magnetic pole face (4) , wherein the means for substantially matching is suitable.
Positioning means with the target device, urging means of the plunger,
And one or more selected from the group consisting of a plunger balancing means.
Is a plurality of electromagnets, wherein the plunger
(3) has the same cross section as the entire length and extends in the axial extension direction.
The plane (4) whose axial parallel magnetic pole face (4) changes in cross section in the axial direction
An electromagnet characterized by the following: a) . 2. The method according to claim 1, wherein the change in cross section is conical or bellmouth.
The electromagnet according to claim 1, wherein the electromagnet is shaped . 3. A magnetic pole surface is fixed to said yoke (2).
And the other pole face is connected to the plunger through a minute gap.
The permanent magnet (9) facing the axis parallel side of (3) is interposed.
Claim 1 or 2 electromagnet wherein it has. 4. A pole face (4) of one of the yokes (2).
The pole face perpendicular to the axis to the axial extension end of the plunger (3) end
4. The device according to claim 1, wherein the device is provided in opposition to the device.
An electromagnet as described in Crab .