CN205507055U - Permanent magnet shimming subassembly - Google Patents
Permanent magnet shimming subassembly Download PDFInfo
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- CN205507055U CN205507055U CN201520988917.7U CN201520988917U CN205507055U CN 205507055 U CN205507055 U CN 205507055U CN 201520988917 U CN201520988917 U CN 201520988917U CN 205507055 U CN205507055 U CN 205507055U
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- shimming
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- hexagonal block
- permanent magnet
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Abstract
The utility model provides a permanent magnet shimming subassembly, by the polar plate body (1), establish shimming part (2) and shimming ring (3) on the polar plate body (1), establish and constitute in shimming ring (3) and air gap (4) that the polar plate was personally experienced sth. Part of the body between (1), shimming part (2) form according to cellular fixed assembling by a plurality of positive hexagonal pieces. The utility model has the advantage of simple structure, the handling ease, installation convenient to use. The biggest characteristics are the requirements that both can reach the shimming, can save work load again, improve shimming efficiency.
Description
Technical field
This utility model relates to a kind of permanent magnet shimming assembly, belongs to magnetic resonance arts.
Background technology
In order to quickly obtain clear real image, patient carrying out Accurate Diagnosis, magnetic resonance imaging system requires that magnet therein can provide a space magnetic field highly uniform on a large scale.The main magnet of permanent-magnet type MRI is after assembling, and the unevenness in magnetic field, sample area is often 1000～1500ppm or higher.Therefore, in the urgent need to being improved the uniformity of main magnet by shimming means.For reaching this purpose it is crucial that the design of body even field assembly for the magnet having pole plate.Method for shimming mainly had two kinds in the past: actively shimming and passive shimming.Actively shimming is exactly to arrange one group of current coil at the suitable position of magnet, and when energized, harmonic component uneven in field, basis can be offset in the magnetic field that coil produces.
The method is frequently used for often leading and superconducting magnet.For Open-style Permanent Magnet MRI magnet, it is contemplated that its basis field uniformity leads difference than often, and open in order to not destroy it, the passive method for shimming of main employing.Passive method for shimming is exactly at permanent magnet pole surface mount small iron plate or little magnetic sheet,
The complementary field produced by iron plate or magnetic sheet eliminates the non-homogeneous component in main field, so that the magnetic field of sample area reaches to be uniformly distributed.Current conventional passive method for shimming shortcoming is that, the sheet number of magnetic sheet is chosen and orientation problem is mainly by the experience of technical staff, and manual test workload is big, shimming efficiency is low.
Summary of the invention
The purpose of this utility model be overcome the deficiencies in the prior art in place of, it is provided that a kind of nuclear magnetic resonance shimming assembly.This shimming assembly is drawn materials easily, and low price is easy for installation, on the premise of not affecting MRI magnet opening size, is remarkably improved the uniformity of MRI magnetic field.
Permanent magnet shimming assembly of the present utility model, the shimming parts (2) by pole plate body (1), being located on pole plate body (1) and grading ring (3), the air gap (4) being located between grading ring (3) and pole plate body (1) are formed, described shimming parts (2) by multiple positive hexagonal blocks by cellular fixing assembled.
Described pole plate body (1) is circular, is made up of pure iron；Pole plate body should be made during magnet design to be in undersaturated condition.
The positive hexagonal block of described shimming parts (2) is made up of pure iron material, silicon steel material, non-crystalline material or nanocrystalline material；The core of described shimming parts is not limited to the one in foregoing four kinds of materials, as long as the residual magnetic flux density higher coercivity relatively low magnetization curve preferable soft magnetic materials of squareness can.
Described grading ring (3) is processed into by pure iron；
Air gap (4) between described grading ring (3) and pole plate body (1) is made up of the insulant of high resistance height magnetic resistance.
The resistance that in described shimming parts, the surface of gap between positive hexagonal block and positive hexagonal block uses method chemically or thermally to improve entirety reduces magnetic resistance, and improves positive hexagonal block insulating properties each other.
The shape of described shimming parts is stepped alveolate texture；The erection method of shimming parts is: the 1st piece of center positive hexagonal block the 1st periphery positive hexagonal block (2,3,4,5,6, No. 7 positive hexagonal blocks) ... ... the-the N periphery positive hexagonal block (quantity is 6N).The contact surface of adjacent positive hexagonal block to be parallel to each other, mutually insulated between adjacent positive hexagonal block.
A diameter of the 10～30mm of described single positive hexagonal block, the gap between adjacent positive hexagonal block is 0.1～0.2mm.
The height of described single positive hexagonal block is 10～30mm.
Can produce in work space certain area uniform magnetic field distribution, by two groups of magnetic materials distribution battle arrays relatively put, two one facing to described work space, the be connected shimming assembly of permanent magnet that the connection yoke dredging yoke towards space outerpace forms of the other end that pole plate assembly that another side is connected with described magnetic material distribution battle array, two one end are distributed battle array with the magnetic material described in a group is made up of pole plate body, shimming parts, air gap between grading ring and grading ring and pole plate.
This utility model carries out the design and installation of shimming assembly according to the distribution curve of magnetic field homogeneity, the uniformity value of the initial fields of permanent magnet was 1000～1500PPM in the past, the uniformity value of initial magnetic field can be reduced to 400～800PPM by the installation of this shimming assembly, save the plenty of time for follow-up accurate shimming.
The utility model has the advantages that simple in construction, handling ease, easy to install.Maximum feature is both to have reached the requirement of shimming, can save again workload, improves shimming efficiency.
Accompanying drawing explanation
Shown in Fig. 1 is the schematic diagram of pole plate body, shimming parts, air gap between grading ring and grading ring and pole plate.
Fig. 2 is that the one of positive hexagonal block fixes erection method, keeps between adjacent positive hexagonal block
Certain gap, is become stepwise to be layered on pole plate to surrounding by center.Wherein the 1st piece of positive hexagonal block is fixed on the center of pole plate, then according to the sequence number of labelling fixedly mounts 2,3,4,5,6, No. 7 positive hexagonal blocks around the 1st successively in figure, 8,9,10,11,12,13,14,15,16,17,18, No. 19 positive hexagonal blocks around 2nd, 20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36, No. 37 positive hexagonal blocks around the 3rd.The installation remaining positive hexagonal block does not has fixing erection sequence, only need to the plate regions of regulation be filled up, and its fixed form uses the mode that screw connects.
Fig. 3 is the schematic diagram of adjacent positive hexagonal block, a diameter of the 10～30mm of shown positive hexagonal block, and the gap between adjacent positive hexagonal block is 0.1～0.2mm.
Fig. 4 is the schematic perspective view of positive hexagonal block, and the height of shown positive hexagonal block is 10～30mm.
Fig. 5 is that the another kind of positive hexagonal block fixes erection method, the black ring around positive hexagonal block
Shape region is reserved area, is used for the last position finely tuning positive hexagonal block, and the peripheral diameter of annular region is 900mm.
Wherein, 1 is pole plate body, and 2 is shimming parts, and 3 is grading ring, and 4 is air gap.
Detailed description of the invention
As shown in Figure 1, permanent magnet shimming assembly of the present utility model, the shimming parts (2) by pole plate body (1), being located on pole plate body (1) and grading ring (3), the air gap (4) being located between grading ring (3) and pole plate body (1) are formed, described shimming parts (2) by multiple positive hexagonal blocks by cellular fixing assembled.
Described pole plate body (1) is circular, is made up of pure iron；Pole plate body should be made during magnet design to be in undersaturated condition.
The positive hexagonal block of described shimming parts (2) is made up of pure iron material, silicon steel material, non-crystalline material or nanocrystalline material；
Described grading ring (3) is processed into by pure iron；
Air gap (4) between described grading ring (3) and pole plate body (1) is made up of the insulant of high resistance height magnetic resistance.
The resistance that in described shimming parts, the surface of gap between positive hexagonal block and positive hexagonal block uses method chemically or thermally to improve entirety reduces magnetic resistance, and improves positive hexagonal block insulating properties each other.
As in figure 2 it is shown, be that the one of positive hexagonal block fixes erection method, between adjacent positive hexagonal block, keep certain gap, center become stepwise to be layered on pole plate to surrounding.Wherein the 1st piece of positive hexagonal block is fixed on the center of pole plate, then according to the sequence number of labelling fixedly mounts 2,3,4,5,6, No. 7 positive hexagonal blocks around the 1st successively in figure, 8,9,10,11,12,13,14,15,16,17,18, No. 19 positive hexagonal blocks around 2nd, 20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36, No. 37 positive hexagonal blocks around the 3rd.The installation remaining positive hexagonal block does not has fixing erection sequence, only need to the plate regions of regulation be filled up, and its fixed form uses the mode that screw connects.The contact surface of adjacent positive hexagonal block to be parallel to each other, mutually insulated between adjacent positive hexagonal block.
As it is shown in figure 5, be that the one of positive hexagonal block fixes erection method, around positive hexagonal block
Black circles region be reserved area, be used for the last position finely tuning positive hexagonal block, the peripheral diameter of annular region is 900mm.
As it is shown on figure 3, a diameter of the 10～30mm of single positive hexagonal block, the gap between adjacent positive hexagonal block is 0.1～0.2mm.
As shown in Figure 4, the height of single positive hexagonal block is 10～30mm.
This utility model carries out the design and installation of shimming assembly according to the distribution curve of magnetic field homogeneity, the uniformity value of the initial fields of permanent magnet was 1000～1500PPM in the past, the uniformity value of initial magnetic field can be reduced to 400～800PPM by the installation of this shimming assembly, save the plenty of time for follow-up accurate shimming.
Claims (4)
1. a permanent magnet shimming assembly, it is characterized in that, the shimming parts (2) by pole plate body (1), being located on pole plate body (1) and grading ring (3), the air gap (4) being located between grading ring (3) and pole plate body (1) are formed, described shimming parts (2) by multiple positive hexagonal blocks by cellular fixing assembled.
Permanent magnet shimming assembly the most according to claim 1, it is characterised in that the shape of described shimming parts is stepped alveolate texture；The erection method of shimming parts is: the 1st piece of center positive hexagonal block the 1st periphery positive hexagonal block, i.e. 2,3,4,5,6, No. 7 positive hexagonal blocks, until N periphery positive hexagonal block, quantity is 6N.
Permanent magnet shimming assembly the most according to claim 1, it is characterised in that a diameter of the 10～30mm of described single positive hexagonal block, the gap between adjacent positive hexagonal block is 0.1～0.2mm.
Permanent magnet shimming assembly the most according to claim 1, it is characterised in that the height of described single positive hexagonal block is 10～30mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520988917.7U CN205507055U (en) | 2015-12-02 | 2015-12-02 | Permanent magnet shimming subassembly |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520988917.7U CN205507055U (en) | 2015-12-02 | 2015-12-02 | Permanent magnet shimming subassembly |
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| Publication Number | Publication Date |
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| CN205507055U true CN205507055U (en) | 2016-08-24 |
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| CN201520988917.7U Active CN205507055U (en) | 2015-12-02 | 2015-12-02 | Permanent magnet shimming subassembly |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105403846A (en) * | 2015-12-02 | 2016-03-16 | 江苏美时医疗技术有限公司 | Shimming assembly of permanent magnet |
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2015
- 2015-12-02 CN CN201520988917.7U patent/CN205507055U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105403846A (en) * | 2015-12-02 | 2016-03-16 | 江苏美时医疗技术有限公司 | Shimming assembly of permanent magnet |
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