JP4594468B2 - electromagnet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnet that generates a mechanical force by energization, particularly generates a strong attractive force by a minute electric input, and can be reduced in size and weight.
[0002]
[Prior art]
Conventionally, as shown in the schematic cross-sectional view of the prior art electromagnet shown in FIG. 12, the fixed magnetic pole surface 14 fixed to one end of the through hole of the bobbin 12 of the coil 11 and the other end of the through hole of the bobbin 12 are slidably inserted. In addition, there is a plunger type electromagnet 10 provided with a movable magnetic pole surface 25 that contacts and separates from the fixed magnetic pole surface 14 .
[0003]
As a conventional technique for improving the shapes of the fixed magnetic pole surface 14 and the movable magnetic pole surface 25 of the electromagnet 10 , for example, Japanese Patent Publication No. 61-41123 discloses a concave surface on the surface of the fixed member facing the cylindrical movable iron core. An electromagnet is disclosed in which a member provided on the outer peripheral portion of the fixing member is tapered so that a tapered portion is formed on the outer peripheral surface thereof. This electromagnet is designed to maintain a large attraction force especially in the attraction operation when the movable iron core moves back and forth with respect to the fixed member. The accompanying FIGS. 4 and 5 show graphs comparing the attraction characteristics of solenoids equipped with a generally known tapered plunger. Stroke end (position where the movable magnetic pole surface is farthest from the fixed magnetic pole surface) It has been shown that the suction characteristics in are significantly improved.
[0004]
Japanese Laid-Open Patent Publication No. 59-177904 discloses a solenoid characterized in that the contact surfaces of the fixed iron core and the movable iron core ( plunger ) are each formed in a spiral shape. And the attraction force characteristics of the solenoid are determined by the magnetic circuit cross-sectional area and the coil winding specifications. Conventionally, in order to improve the attraction force characteristics at the maximum stroke position, conventionally, the movable iron core ( plunger ) and the fixed iron core It is described that various ideas are applied to the shape of the contact surface. For example, measures have been taken to increase the area of the opposing magnetic pole, shorten the distance between the contact surfaces at the maximum stroke position, or reduce the magnetic resistance and magnetic leakage in the magnetic circuit. To mention. And it describes about the shape change of the conventional magnetic pole surface for exhibiting a suitable attraction force characteristic. These are schematically shown in FIGS. 13A to 13E. In the figure, 31 indicates the moving stroke of the movable iron core ( plunger ) , and 32 indicates the facing distance between the magnetic pole faces. In spite of such contrivance, a solenoid that has a large initial suction force and can obtain a substantially constant suction force over the entire stroke has not been obtained, especially in a long stroke solenoid, and it was described as a technical problem. ing. In the technique disclosed in Japanese Patent Application Laid-Open No. 59-177904, in a solenoid in which a movable iron core ( plunger ) horizontally moves with voltage application, the opposing surface of the movable iron core ( plunger ) and the fixed iron core facing each other is formed in a spiral shape. Further, it is described that the attraction force characteristic with respect to the moving stroke of the movable iron core ( plunger ) is improved. And the attached FIG. 4 shows that it is remarkably improved as compared with the conventional suction force characteristics.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a smaller and lighter electromagnet that generates a high attractive force with a smaller electric input than a conventional electromagnet.
[0006]
The present invention proposes the following means in order to improve the attractive force characteristics accompanying the movement of the movable iron core ( plunger ) that effectively drives the mechanical load of the electromagnet.
[0007]
[Means for Solving the Problems]
The technical means of the present invention for solving the above-mentioned problem is that, in the electromagnet in which the magnetic pole surface of the movable iron core moving in the axial direction contacts and separates from the magnetic pole surface of the fixed iron core, the magnetic poles excluding the central portion and the outer peripheral portion of one magnetic pole surface An electromagnet is characterized in that an axial recess is provided on the surface, and a protrusion that enters the recess is protruded from the other magnetic pole surface. In this case, the concave portion may have a cross-sectional shape having a discontinuous notch in the circumferential direction of the outer peripheral portion. In other words, the outer peripheral portion may be completely continuous with no concave portions over the entire circumference, or may be a discontinuous portion that is partially cut and formed with concave portions.
[0008]
The concave portion may have any cross-sectional shape that is arranged point-symmetrically with respect to the center point of the magnetic pole surface, or axially symmetric with respect to a plurality of axes passing through the center point, for example, one or more concentric or eccentric circles. It may be an annular cross section.
[0009]
The attractive force F generated by the electromagnet is expressed as follows: U is the magnetomotive force acting on the magnetic path, P is the permeance that is the reciprocal of the magnetic resistance of the magnetic path gap, and X is the axial displacement of the movable core ( plunger ) . By ignoring the magnetic resistance of the iron core of the magnetic path, it can be calculated by the following formula.
[0010]
^{F = (U 2/2)} × dP / dX
Where F: attractive force U: magnetomotive force acting on the magnetic path P: permeance X: axial displacement. That is, the attraction force of the electromagnet is proportional to the product of the square of the energization current value and the rate of change of the magnetic path paamance associated with the displacement of the movable core ( plunger ) .
[0011]
If the electric input of the electromagnet is a constant value, the magnetomotive force U acting on the magnetic path is a constant value. In order to generate a strong attractive force under this condition, the magnetic pole surface accompanying the axial displacement of the movable iron core ( plunger ) It is necessary to select a magnetic pole face shape that increases the change rate dP / dX of the gap permeance. The above configuration of the present invention is for realizing this.
[0012]
In the electromagnet of the present invention, it is preferable that the side surface of the protrusion has an inclination angle with respect to the side surface of the concave portion. It is preferable to set the length of the second recess to be shorter than the axial length and to form the second recess having a depth smaller than that of the recess so as to effectively prevent a reduction in suction force during the stroke. It has also been found that there is almost no difference in the attractive force improvement effect even if a coaxial through hole is provided in the axial direction of the protrusion of the other magnetic pole surface.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The technical means of the present invention will be described with reference to a schematic structural cross-sectional view of an electromagnet 10 of one embodiment of the present invention shown in FIG. 1 and its AA and BB arrow views. The present invention basically comprises a fixed pole face 1 4 provided on one end of the through hole of the bobbin 12 to turn the coil 11 wound, is inserted slidably from the other end of the through hole of the bobbin 12, a fixed magnetic pole an electromagnet 10 composed of a movable pole face 25 of the movable core (plunger) 21 that contact and separation to the surfaces 1 4. The cylindrical movable core (plunger) 21 in the example of Figure 1, the movable iron core (plunger) 21 and concentric recesses 24 are provided in a portion except for the central portion 23 and the peripheral portion 22, the fixation of the fixed iron core 13 The magnetic pole surface 14 includes a protrusion 15 and a circumferential fringe 16. The movable magnetic pole surface 25 is in contact with and away from the fixed magnetic pole surface 14, and the protrusion 15 is fitted into the recess 24 through a minute gap.
[0014]
By adopting such a configuration of the magnetic pole face, it is easy to effectively increase the value of the change rate dP / dX of the magnetic pole face gap, and the magnetomotive force U and plunger diameter of the electromagnet 10 are set. Corresponding to the value, the dimension of the gap between the fitting portion of the fixed magnetic pole surface 14 and the movable magnetic pole surface 25 can be set appropriately to increase the rate of change of the magnetic pole surface gap permeance.
[0015]
Another embodiment of the present invention will be described with reference to the magnetic pole surface cross-sectional view of FIG. 2 and its CC and DD arrow views. One magnetic pole of this embodiment, for example, the fixed iron core 13, has a columnar magnetic body axial length b of the central portion 23 shorter than the magnetic body axial length a of the peripheral portion 22, and the protrusion 15 has a tip opening 18. And a circumferential magnetic fringe 16 are formed on a cylindrical magnetic pole surface, and the axial orthogonal surfaces of both magnetic pole surfaces are coaxially contacted and separated, and the axially parallel cylindrical inner and outer surfaces are fitted together with a predetermined gap therebetween. And
[0016]
Another embodiment of the present invention will be described with reference to the magnetic pole surface sectional view of FIG.
[0017]
In this embodiment, the inner and outer surfaces of the cylinder fitted through a predetermined gap of the magnetic pole surfaces form a magnetic pole surface that forms an inclined surface with a predetermined angle θ with respect to the mating magnetic pole cylinder inner and outer surfaces. As the predetermined angle, not only a linear inclination but also a stepped or curved inclined surface can be adopted as necessary.
[0018]
The configuration of the magnetic pole surface in this embodiment makes it possible to improve the attractive force characteristics by adjusting the value of the change rate dP / dX of the permeance in a specific range of the stroke of the electromagnet.
[0019]
4 and 5 show test data showing the effects of the present invention. 4A is a front view and FIG. 4B is a longitudinal sectional view showing the shape and dimensions of the electromagnet 10 of the embodiment used in the test. The front external dimensions are 20 mm × 16 mm, and the diameter of the movable iron core ( plunger ) 21 is 7 mmφ. The outer length of the longitudinal sectional view is 25.2 mm, and the stroke of the movable iron core ( plunger ) 21 is 5 mm. The constant applied voltage 32V of the coil 11 and the resistance of the coil 11 are 150Ω. The height L of the fixed iron core 1 3 of the central portion 23 shown in examining Figure 5 the suction force characteristics varied in the range from 0 to 5 mm. As is apparent from FIG. 5, when L = 1.5 to 5.0 mm, the suction force at the stroke of 5 mm is improved by 40 to 90% with respect to the characteristics of L = 0 mm (without the central protrusion). is doing. Furthermore, L = 1.5 mm and L = 3.0 mm show a larger suction force than L = 5 mm. The reason for this is not clear, but it is thought to be due to the increase in dP / dX.
[0020]
That is, in the present invention, as shown in the graph of the attraction characteristic of the present invention shown in FIG. 5, the value of the change rate dP / dX of the magnetic pole face gap is effectively increased to generate a high attraction force. Improvements to maintain high suction force characteristics during the stroke due to the change in the stroke are now possible.
[0021]
Another embodiment of the present invention will be described with reference to FIGS. 6 to 10 are front views of one magnetic pole surface according to the present invention, and FIG. 11 is a longitudinal sectional view of another example. FIG. 6 schematically shows an example in which the recess 24 provided in the movable magnetic pole surface 25 has an arbitrary number of arbitrary shapes arranged at point-symmetrical positions with respect to the central point of the movable magnetic pole surface 25. 7, 8, and 9 show an example in which an arbitrary number and an arbitrary shape of concave portions 24 are disposed at arbitrary axially symmetric positions with respect to one or a plurality of axes 26 passing through the center of the movable magnetic pole surface 25. . Although the cross-sectional shape of the recessed part 24 has illustrated the circular thing, what kind of shape may be sufficient. FIG. 10 shows an example in which the recess 24 is a concentric ring shape. In FIG. 11, the through hole 17 is provided in the center portion of the magnetic pole surface having the protrusion portion 15 in which the height of the central portion 23 located on the center side from the concave portion 24 is lower than the height of the peripheral edge portion 22. Indicates that it is missing. In this case, by the contact of the stroke end of the movable iron core and the front end of the peripheral edge portion 22 abuts on the outer peripheral side of the circumferential fringe 16 of the projections 15, or the bottom surface of the recess 24 with the tip of the projection 15, sufficient suction There is no problem because retention is secured.
[0022]
【The invention's effect】
According to the present invention, compared with the electromagnets of the prior art, a high attractive force can be generated with a smaller electric input, and a smaller and lighter electromagnet can be obtained. The place to contribute is great.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a longitudinal sectional view of a schematic structure, (b) an AA arrow view, and (c) a BB arrow view of an example.
FIGS. 2A and 2B are (a) a schematic structure longitudinal sectional view, (b) a CC arrow view, and (c) a DD arrow view of another embodiment.
3A is a schematic cross-sectional view of a schematic structure of another embodiment, FIG. 3B is a view taken along the line EE, and FIG. 3C is a view taken along the line FF.
4A is a front view and FIG. 4B is a longitudinal sectional view of a test electromagnet.
FIG. 5 is a graph of suction characteristics.
FIG. 6 is an explanatory diagram of another embodiment.
FIG. 7 is an explanatory diagram of another embodiment.
FIG. 8 is an explanatory diagram of another embodiment.
FIG. 9 is an explanatory diagram of another embodiment.
FIG. 10 is an explanatory diagram of another embodiment.
FIG. 11 is an explanatory diagram of another embodiment.
FIG. 12 is a longitudinal sectional view of a conventional electromagnet.
FIG. 13 is an explanatory diagram of a conventional electromagnet.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Electromagnet 11 Coil 12 Bobbin 13 Fixed iron core 14 Fixed magnetic pole surface 15 Protrusion part 16 Circumferential fringe 17 Through-hole 18 Tip opening 21 Movable iron core (plunger)
22 Peripheral portion 23 Center portion 24 Recessed portion 25 Movable magnetic pole surface 26 Axis passing through the center of the magnetic pole surface 31 Stroke 32 Opposite distance

Claims (5)

In the electromagnet pole face of the movable iron core that moves axially approaching and moving away from the pole face of the fixed iron core, the one pole face center and Rutotomoni provided axially concave pole face except the outer peripheral portion of said central portion An electromagnet characterized in that an axial length is set to be shorter than an axial length of the outer peripheral portion, and a protruding portion that enters the concave portion protrudes from the other magnetic pole surface. 2. The electromagnet according to claim 1 , wherein the concave portion has an arbitrary cross-sectional shape arranged at a position that is point-symmetric with respect to a central point of the magnetic pole surface or axially symmetric with respect to an axis passing through the central point . The electromagnet according to claim 1, wherein the concave portion has one or a plurality of annular cross sections . The electromagnet according to any one of claims 1 to 3 , wherein the protrusion side surface has an inclination angle with respect to the side surface of the recess. The electromagnet according to claim 1 , wherein a coaxial through hole is provided in the axial direction of the protruding portion of the other magnetic pole surface .

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