CN212516755U - Solenoid coil and magnetic measuring apparatus including the same - Google Patents
Solenoid coil and magnetic measuring apparatus including the same Download PDFInfo
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- CN212516755U CN212516755U CN202022075216.8U CN202022075216U CN212516755U CN 212516755 U CN212516755 U CN 212516755U CN 202022075216 U CN202022075216 U CN 202022075216U CN 212516755 U CN212516755 U CN 212516755U
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Abstract
The utility model relates to a solenoid coil and magnetic measurement equipment including solenoid coil. According to an embodiment, a solenoid coil may include a plurality of coil turns that are uniformly wound in an axial direction of the solenoid coil. The diameter of the solenoid coil gradually decreases in a direction from the center of the axis of the solenoid coil toward both ends. Preferably, in a cross-section through an axis of the solenoid coil, the solenoid coil has a parabolic shape that is symmetrical about the axis of the solenoid coil. The solenoid coil is capable of providing a uniform magnetic field in its interior space, thereby meeting the needs of various magnetic measurement applications.
Description
Technical Field
The present invention relates generally to the field of magnetic field measurement techniques, and more particularly, to a solenoid coil capable of generating a uniform magnetic field, a method of manufacturing the same, and a magnetic measuring apparatus including the same.
Background
Magnetic measuring devices such as magnetometers, nuclear magnetic resonance gyroscopes generally comprise means for generating a homogeneous magnetic field, for example for counteracting an ambient magnetic field, or for balancing and thus determining the magnetic field to be measured. Common means for generating a uniform magnetic field include solenoid coils, helmholtz coils, and the like. The helmholtz coil includes two coaxial circular coils having a radius R, and an axial distance h between the two coils is set to be equal to the radius R, thereby generating a magnetic field whose nonuniformity is minimized, i.e., the second reciprocal of the axial magnetic field is zero, at an axial center position of the two coils. However, the helmholtz coil requires a bobbin to be manufactured to fix the two coils relatively at a predetermined position, so that the manufacturing process is complicated and it is difficult to miniaturize. Furthermore, the helmholtz coil requires a larger current magnitude to generate the predetermined magnetic field than the solenoid coil, which is not energy efficient. Thus, helmholtz coils are not the best choice for some small, large-scale magnetic measurement applications.
The solenoid coil is simple to wind, does not need a framework, can wind a smaller coil easily, and can be widely applied to magnetic measuring equipment with various specifications. Theoretically, when the solenoid coil is infinite long, the magnetic field generated inside the solenoid coil is uniform. However, when the solenoid coil has a finite length L, as shown in fig. 1, the magnetic lines of force 11 diverge at both ends of the solenoid 10, causing the magnetic field inside to become uneven. Therefore, how to improve the uniformity of the magnetic field inside the solenoid coil has been a subject of study.
Patent application 201811304808.3 entitled "an unequal spacing solenoid" discloses a solenoid coil that compensates for the magnetic field strength at the ends of the coil by gradually increasing the spacing between adjacent coils from the ends toward the center of the coil to improve the magnetic field uniformity. Patent application 201910465922.2 entitled "a magnetometer measurement Range and gradient margin indicator measurement apparatus" discloses another solenoid coil that compensates for the magnetic field strength at both ends of the solenoid coil to improve the magnetic field uniformity by additionally winding a plurality of compensation coils around the periphery of the coil at both end positions of the solenoid coil. However, these methods require precise control of the winding process of the coil to wind the coil turns at predetermined positions, which is difficult to construct, and the process deviation during winding may cause the uniformity of the actually generated magnetic field to fail to meet the design requirements.
SUMMERY OF THE UTILITY MODEL
An aspect of the present invention is to provide a solenoid coil, which may include a plurality of coil turns that are uniformly wound in an axis direction of the solenoid coil. The diameter of the solenoid coil gradually decreases in a direction from the center of the axis of the solenoid coil toward both ends.
In a cross-section through an axis of the solenoid coil, the solenoid coil may have a parabolic shape that is symmetrical about the axis of the solenoid coil.
The parabolic shape can satisfy the formula
Where L is the length of the solenoid coil, γ is the ratio between the length L of the solenoid coil and the maximum diameter D at the center position, x is the distance from the center of the axis in the direction of the axis of the solenoid coil, and a is a second order coefficient.
The value range of the quadratic term coefficient a can be
Preferably, the value of the quadratic term coefficient a is about
The solenoid coil may further include a bobbin, which may have a hollow structure, and the plurality of coil turns are uniformly wound around the bobbin. The bobbin may have the parabolic shape in a cross section passing through an axis of the solenoid coil.
An aspect of the present invention is to provide a method of manufacturing a solenoid coil, including: manufacturing a bobbin having a circular shape in a cross section perpendicular to an axis of the bobbin, the bobbin having a diameter gradually decreasing in a direction from a center of the axis of the bobbin toward both ends; and winding a plurality of coil turns on the framework, wherein the plurality of coil turns are uniformly wound in the direction along the axis of the framework.
In a cross-section through the axis, an outer surface of the skeleton may have a parabolic shape symmetrical about the axis.
The parabolic shape can satisfy the formula
Where L is the length of the skeleton, γ is the ratio between the length L of the skeleton and the maximum diameter D at the center position, x is the distance from the center of the axis in the direction of the axis of the skeleton, and a is a quadratic coefficient.
The value range of the quadratic term coefficient a can be
Preferably, the value of the quadratic term coefficient a is about
The method may further include removing the bobbin after winding the plurality of coil turns.
It is an aspect of the present invention to provide a magnetic measuring device comprising any of the solenoid coils described above.
Drawings
Fig. 1 shows a prior art solenoid coil.
Fig. 2 illustrates a solenoid coil according to an exemplary embodiment of the present invention.
Fig. 3 is a graph showing the range of values of the quadratic coefficient of the parabolic shape of the solenoid coil.
Fig. 4 illustrates a solenoid coil according to another exemplary embodiment of the present invention.
Fig. 5 is a flowchart illustrating a method of manufacturing a solenoid coil according to an exemplary embodiment of the present invention.
Fig. 6 shows a comparison of magnetic field uniformity in the interior space of a solenoid coil according to an embodiment of the present invention and a prior art solenoid coil.
Detailed Description
Exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.
Fig. 2 illustrates a solenoid coil 100 including a plurality of coil turns 110 according to an exemplary embodiment of the present invention. As shown in fig. 2, the diameter of the solenoid coil 100 gradually decreases in a direction from the center O point of the axis X axis of the solenoid coil 100 toward both ends.
Fig. 2 shows a cross-sectional view of the solenoid coil 100 in the X-Y plane, where the X-axis is the central axis of the solenoid coil 100 and the Y-axis is the vertical axis through the solenoid center O point on the X-axis. The plurality of coil turns 110 may be uniformly wound in the X-axis direction. Although fig. 2 shows one layer of coil turns 110 being densely wound, a plurality of coil turns 110 may be wound with uniform intervals, or a plurality of layers of coil turns 110 may be wound. As is readily seen in the cross-sectional view of fig. 2, the diameter of the solenoid coil 100 gradually decreases from the center point O toward both ends. Although not shown, the solenoid coil 100 may have a circular shape in a cross section perpendicular to the X-axis. Solenoid coil 100 may have a length L, corresponding to a value on the X-axis from-L/2 to + L/2. The solenoid coil 100 has a maximum diameter D at the center O point, whereby the aspect ratio γ of the solenoid coil 100 can be determined to be L/D. When the diameter of the solenoid coil 100 is reduced toward both ends, unevenness due to divergence of magnetic lines at both ends can be compensated for, thereby significantly improving the uniformity of the magnetic field within the solenoid coil 100.
Preferably, in a cross-section through the X-axis (i.e., an X-Y plane), the solenoid coil 100 may have a parabolic shape that is vertically symmetrical about the X-axis, as shown in fig. 2. In fig. 2, in order to clearly show the parabolic shape, dotted lines corresponding to the shape of the coil turns 110 are shown on both upper and lower sides of the coil turns 110, which are used only to show the parabolic shape of the coil turns 110, not a specific structure included in the solenoid coil 100. In the X-Y plane coordinate system shown in fig. 2, the parabolic shape of the solenoid coil 100 can be expressed by the following formula (1):
where L is the length of the solenoid coil 100, γ is the ratio between the length of the solenoid coil L and the maximum diameter D at the center position O, X is the distance from the center position O in the X-axis direction of the solenoid coil 100, a is the coefficient of the quadratic term, and Y is the position of the coil turn 110 on the Y-axis, i.e., Y is the radius of the coil turn 110 at the X-position.
For some magnetic measurement applications, the solenoid coil length L and the maximum diameter D may be predetermined. At this time, by optimizing the value of the quadratic term coefficient a, the shape of the solenoid coil 100 can be adjusted, thereby improving the uniformity of the magnetic field in the internal space of the solenoid coil 100. Fig. 3 shows the optimized range of the quadratic term coefficient a. As shown in fig. 3, the range of the quadratic term coefficient a can be represented by the following formula (2):
preferably, the value of the quadratic term coefficient a may be about
Fig. 4 illustrates a solenoid coil 200 according to another exemplary embodiment of the present invention, similar to the solenoid coil 100 illustrated in fig. 2, the solenoid coil 200 may also include a plurality of coil turns 110, and the diameter of the solenoid coil 200 is gradually reduced in a direction from a center O point of an axis X axis of the solenoid coil 200 toward both ends. Solenoid coil 200 may also have other features of solenoid coil 100.
The structure of the bobbin 120 is not limited to a hollow structure, and for example, in the case where the bobbin 120 can be eliminated from the finished solenoid coil, the bobbin 120 may also have a non-hollow structure, such as a structure containing a filler or a unitary solid structure. The manner in which the skeleton is removed will be discussed later.
Fig. 5 illustrates a flow chart of a method 300 of manufacturing a solenoid coil, according to an exemplary embodiment of the present invention. As shown in fig. 5, a method 300 of manufacturing a solenoid coil includes a step S310 of preparing a bobbin and a step S320 of winding a coil on the bobbin. The bobbin manufactured at step S310 may be the bobbin 120 shown in fig. 4, and the bobbin 120 may have a circular shape in a cross section perpendicular to an axis (e.g., X-axis shown in fig. 4) of the bobbin 120. Also, the diameter of the bobbin 120 gradually decreases in a direction from the center of the axis of the bobbin 120 (e.g., the origin O shown in fig. 4) toward both ends.
The bobbin 120 may be made of polytetrafluoroethylene, polyvinylidene fluoride, or polyimide, or may be made of a ceramic material or a non-magnetic metal material. In the case of using a plastic material such as polytetrafluoroethylene, polyvinylidene fluoride, or polyimide, it can be formed by a general thermoplastic processing method such as extrusion molding, injection molding, press molding, or the like. In the case of using a ceramic material, it can be formed by a method such as extrusion molding, dry press molding, hot press molding, slip casting, roll film molding, isostatic pressing, hot press molding, and tape casting. In the case of using a non-magnetic metal material such as an aluminum material, molding can be performed by a method such as extrusion. Alternatively, the skeleton 120 may be formed by a 3D printing method.
In step S320, a plurality of coil turns 110 may be wound on the bobbin 120, and the plurality of coil turns 110 may be uniformly wound in a direction along an axis (e.g., an X-axis shown in fig. 4) of the bobbin 120.
Alternatively, referring to fig. 4, in a cross-section (X-Y plane) passing through the X-axis of the solenoid coil 200, the outer surface of the bobbin 120 may have a parabolic shape that is vertically symmetrical about the X-axis, which is the same shape as the solenoid coil 200.
In the X-Y plane coordinate system shown in fig. 4, the parabolic shape of the skeleton 120 can be expressed by the following formula (3):
where L is the length of the skeleton 120, γ is the ratio between the length L of the skeleton 120 and the maximum diameter D at the center position O, X is the distance from the center position O in the X-axis direction of the skeleton 120, a is a quadratic coefficient, and Y is the position of the skeleton 120 on the Y-axis, i.e., | Y | is the radius of the skeleton 120 at the X-position.
For some magnetic measurement applications, the skeleton length L and the maximum diameter D may be predetermined. At this time, by optimizing the value of the quadratic term coefficient a, the shape of the skeleton 120 can be adjusted, thereby improving the magnetic field uniformity in the internal space of the skeleton 120. The range of the quadratic term coefficient a can be expressed by the following formula (4):
preferably, the value of the quadratic term coefficient a may be about
As shown in fig. 5, the method 300 of manufacturing a solenoid coil may further include a step S330 of removing the bobbin 120 after the plurality of coil turns 110 are wound. The method of removing the skeleton 120 may be a crushing method, for example, crushing the skeleton 120 of the ceramic material by an impact force. Alternatively, the method of removing the backbone 120 may be a dissolving method, for example, dissolving away the backbone 120 such as a polyvinylidene fluoride material by a solvent such as NN dimethylacetamide or the like. Those skilled in the art will recognize that the method of removing the bobbin 120 is not limited thereto, and that a method capable of removing the bobbin 120 without damaging the solenoid coil may be employed. By removing the bobbin, the energy loss of the solenoid coil can be reduced, and the weight can be reduced, making the solenoid coil easy to install.
In the case of the step S330 of removing the bobbin 120, the bobbin 120 may not be limited to the hollow structure but may be, for example, a structure containing a filler or an integral solid structure, thereby increasing the selection margin of the bobbin in the solenoid coil manufacturing process.
According to an embodiment of the present invention, there may also be provided a magnetic measuring device (not shown) comprising the solenoid coil described in the previous embodiment. The magnetic measuring device may for example be a magnetometer, a nuclear magnetic resonance gyroscope, or the like.
Fig. 6 shows a comparison of magnetic field uniformity in the interior space of a solenoid coil according to an embodiment of the present invention and a prior art solenoid coil.
In fig. 6, the dashed and solid lines show the magnetic field strength of the solenoid coil of the prior art and the solution of the embodiment of the present invention at different distances from the center of 0.0, respectively, in meters (m) and oersted (Oe). As shown in fig. 6, the magnetic field strength in the internal space of the conventional solenoid coil shown by the dotted line sharply decreases with an increase in the distance of 0.0 from the center, the uniformity of the half tube length ranges from 0% to-0.6%, and the magnetic field strength at the half position on one side of the center (i.e., at the positions of-L/4 and L/4 in the case where the tube length is L) decreases by 0.6% from the magnetic field strength at the center. The magnetic field strength in the inner space of the solenoid coil of the preferred embodiment of the present invention (for example, the second order coefficient a takes a preferred value) shown by the solid line is kept generally constant as the distance from the center increases by 0.0, the uniformity of the half tube length thereof ranges from 0 to-0.08%, and the magnetic field strength at the position half to the center (i.e., the positions of-L/4 and L/4 in the case where the tube length is L) is reduced by 0.08% from the magnetic field strength at the center.
Compared with the solenoid coil of the prior art, the utility model discloses the solenoid coil has the promotion that is showing in the aspect of the magnetic field degree of consistency, can provide even magnetic field in its inner space to satisfy the needs that various magnetic measurements were used.
Although the embodiments of the present invention have been shown and described, the above embodiments are only for illustrating the technical conception and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention, and thus the protection scope of the present invention cannot be limited thereby. It will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (7)
1. A solenoid coil comprising a plurality of coil turns, characterized in that:
the plurality of coil turns are uniformly wound in the direction of the axis of the solenoid coil;
the diameter of the solenoid coil gradually decreases in a direction from the center of the axis of the solenoid coil toward both ends.
2. The solenoid coil of claim 1, wherein in a cross-section through an axis of the solenoid coil, the solenoid coil has a parabolic shape that is symmetric about the axis of the solenoid coil.
3. The solenoid coil of claim 2, wherein said parabolic shape satisfies the following equation:
where L is the length of the solenoid coil, γ is the ratio between the length L of the solenoid coil and the maximum diameter D at the center position, x is the distance from the center of the axis in the direction of the axis of the solenoid coil, and a is a quadratic coefficient.
4. The solenoid coil of claim 3, wherein said quadratic coefficient a ranges from:
5. the solenoid coil of claim 4 wherein said second order coefficient a is approximately the value of
6. The solenoid coil of claim 2 further comprising a bobbin having a hollow configuration, the plurality of coil turns being uniformly wound on the bobbin, the bobbin having the parabolic shape in a cross-section through an axis of the solenoid coil.
7. A magnetic measuring device comprising the solenoid coil of any of claims 1 to 6.
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| CN202022075216.8U CN212516755U (en) | 2020-09-21 | 2020-09-21 | Solenoid coil and magnetic measuring apparatus including the same |
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| CN202022075216.8U CN212516755U (en) | 2020-09-21 | 2020-09-21 | Solenoid coil and magnetic measuring apparatus including the same |
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