CN105390229B - A kind of permanent-magnet and the magnet apparatus for MRI system - Google Patents
A kind of permanent-magnet and the magnet apparatus for MRI system Download PDFInfo
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- CN105390229B CN105390229B CN201510920040.2A CN201510920040A CN105390229B CN 105390229 B CN105390229 B CN 105390229B CN 201510920040 A CN201510920040 A CN 201510920040A CN 105390229 B CN105390229 B CN 105390229B
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Abstract
The invention discloses a kind of permanent-magnets, including：The column inner magnet made of permanent-magnet material, the first column side magnet and the second column side magnet；First column side magnet is co-axially located at the outside of the column inner magnet, second column side magnet is co-axially located at the outside of first column side magnet, the column inner magnet, first column side magnet concave curved surface approximate with all or part of different and formation of the height of second column side magnet, the direction of magnetization of the column inner magnet is axial, the direction of magnetization of first column side magnet is with the axial direction at first angle, the direction of magnetization of second column side magnet is with the axial direction at second angle, the second angle is greater than or equal to the first angle.The invention also discloses a kind of magnet apparatus for MRI system.
Description
Technical field
The present invention relates to permanent magnet technical field more particularly to a kind of permanent-magnet and for MRI system
Magnet apparatus.
Background technology
Magnetic resonance imaging is also referred to as magnetic resonance imaging (Magnetic Resonance Imaging, abbreviation MRI), is to utilize
Atomic nucleus signal produced by the internal resonance of magnetic field carries out a kind of technology of image reconstruction, and nuclear magnetic resonance technique is applied not only to physics
And chemistry, it is also applied to clinical medicine domain.
MRI machine can be generally divided into three parts：Magnet system, nuclear magnetic resonance chemical analyser and image procossing display system
System.Wherein, magnet system is made of magnet apparatus and coil, and magnet apparatus is the main composition part of MRI machine, is decide
The picture quality and working efficiency of MRI machine, meanwhile, magnet apparatus is also cost maximum, the highest portion of maintenance expense in MRI machine
Point.The main performance index of magnet apparatus includes magnetic field intensity, uniformity of magnetic field etc., and magnetic field intensity is higher, used permanent magnetism
Material is more, and cost is higher, and uniformity of magnetic field can also decline therewith, therefore, how to be improved using less permanent-magnet material
Magnetic field intensity and uniformity of magnetic field are the key technologies of magnet design.
In the prior art, magnet apparatus schematic diagram shown in Figure 1, the magnet apparatus include hollow yoke 1a, in
The lower permanent-magnet 3a of upper permanent-magnet 2a, the setting of hollow yoke 1a inner surfaces lower part that empty yoke 1a inner surfaces top is arranged,
It is provided with magnetic homogenizing pole plate 4a and magnetic homogenizing pole plate 2A on upper permanent-magnet 2a and lower permanent-magnet 3a apparent surfaces,
Air gap 3A is the working region that magnet apparatus provides.Arrow in upper permanent-magnet 2a and lower permanent-magnet 3a indicates respective magnet
The direction of magnetization, the arrow in air gap 3A indicates working region magnetic direction.The magnetic field intensity of the magnet apparatus working region compared with
Low, generally in 0.4 tesla or hereinafter, to improve magnetic field intensity it is necessary to use a large amount of permanent-magnet magnetic material, this to be used for
The cost of the permanent-magnet of MRI greatly improves, but also very heavy.
Invention content
In view of this, the main purpose of the embodiment of the present invention is to provide a kind of permanent-magnet and is used for Magnetic resonance imaging
The magnet apparatus of system so that magnet structure is simple and easy to process, and magnet structure is made to be capable of providing higher magnetic field intensity
And uniformity of magnetic field.
To achieve the above object, an embodiment of the present invention provides a kind of permanent-magnet, the permanent-magnet includes：By permanent magnetism
Column inner magnet made of material, the first column side magnet and the second column side magnet；
First column side magnet is co-axially located at the outside of the column inner magnet, and second column side magnet is same
Axis is arranged in the outside of first column side magnet, the column inner magnet, first column side magnet and described second
The height of column side magnet is all or part of different and forms approximate concave curved surface, and the direction of magnetization of the column inner magnet is axis
To the direction of magnetization and the axial direction of first column side magnet are at first angle, the magnetization of second column side magnet
With the axial direction at second angle, the second angle is greater than or equal to the first angle in direction.
Optionally, the column inner magnet is spliced into approximate solid cylinder for rectangular multiple magnetic patch by section and forms, institute
It is that rectangular multiple magnetic patch are spliced into approximate hollow cylinder and form that the first column side magnet, which is stated, by section, second column side magnetic
Body is spliced into approximate hollow cylinder for rectangular multiple magnetic patch by section and forms；The outer surface of the column inner magnet and described the
The inner surface of one column side magnet fits closely, outer surface and second column side magnet of first column side magnet
Inner surface fits closely.
Optionally, the peripheral magnetic patch of second column side magnet includes magnetic patch that section is square and/or section is
Rectangular magnetic patch.
Optionally, the column inner magnet, first column side magnet and second column side magnet height according to
It is secondary incremental；Alternatively, the column inner magnet is equal with the height of first column side magnet, second column side magnet
Height is more than the height of first column side magnet；Alternatively, first column side magnet and second column side magnet
Height it is equal, the height of the column inner magnet is less than the height of first column side magnet.
Optionally, the first angle is no more than 30 degree with the second angle.
The embodiment of the present invention additionally provides a kind of magnet apparatus for MRI system, including：It is yoke, described
First main magnet of yoke inner surface top setting, is coaxially set the second main magnet of yoke inner surface lower part setting respectively
It is placed in first main magnet and the first pole plate and the second pole plate on the second main magnet apparent surface；
First main magnet is such as permanent-magnet described in any one of claim 1 to 5 with second main magnet；Institute
State the column inner magnet of the first main magnet the direction of magnetization be axially upwards, the first column side magnet of first main magnet with
The direction of magnetization of second column side magnet deviates from the direction of magnetization of the column inner magnet of first main magnet；Second master
The direction of magnetization of the column inner magnet of magnet is the first column side magnet of second main magnet and the second column axially upwards
The direction of magnetization of side magnet is directed to the direction of magnetization of the column inner magnet of second main magnet.
Optionally, the diameter of first pole plate is equal with the outer diameter of the second column side magnet of first main magnet,
First pole plate fits closely first main magnet side and first main magnet；The diameter of second pole plate
It is equal with the outer diameter of the second column side magnet of second main magnet, second pole plate to second main magnet side
It is fitted closely with second main magnet.
Optionally, the diameter of first pole plate is equal with the outer diameter of the first column side magnet of first main magnet,
First pole plate fits closely first main magnet side and first main magnet；The diameter of second pole plate
It is equal with the outer diameter of the first column side magnet of second main magnet, second pole plate to second main magnet side
It is fitted closely with second main magnet.
Optionally, the magnet apparatus further includes：It is coaxially disposed respectively in first pole plate and the second pole plate phase
To the first column leak stopping magnet ring and the second column leak stopping magnet ring on surface；The outer diameter of the first column leak stopping magnet ring with it is described
The outer diameter of second column side magnet of the first main magnet is equal, outer diameter and the described second main magnetic of the second column leak stopping magnet ring
The outer diameter of second column side magnet of body is equal.
Optionally, the magnet apparatus further includes：It is coaxially disposed the second column side magnetic in first main magnet respectively
The first column leak stopping magnet ring on second column side magnet apparent surface of body and second main magnet and the second column leak stopping
Magnet ring；The outer diameter of the first column leak stopping magnet ring is equal with the outer diameter of the second column side magnet of first main magnet, institute
The outer diameter for stating the second column leak stopping magnet ring is equal with the outer diameter of the second column side magnet of second main magnet.
Optionally, the first column leak stopping magnet ring is made of at least two first leak stopping magnetic patch, the first leak stopping magnetic
Block uses permanent-magnet material or ferromagnetic material, when the first leak stopping magnetic patch uses permanent-magnet material, the first leak stopping magnetic patch
The direction of magnetization is radially outward；The second column leak stopping magnet ring is made of at least two second leak stopping magnetic patch, and described second is stifled
Magnetic flux leakage block uses permanent-magnet material or ferromagnetic material, and when the second leak stopping magnetic patch uses permanent-magnet material, described second is stifled
The direction of magnetization of magnetic flux leakage block is radially-inwardly.
Optionally, first pole plate and second pole plate is plane to air side；Alternatively, first pole
Plate has a groove respectively to the symmetric position of air side, and second pole plate has the symmetric position of air side one recessed respectively
Slot.
Permanent-magnet provided in an embodiment of the present invention and magnet apparatus for MRI system, the permanent-magnet
Including the column inner magnet made of permanent-magnet material, the first column side magnet and the second column side magnet, column inner magnet, first
Column side magnet concave curved surface approximate with all or part of different and formation of the height of the second column side magnet.As it can be seen that the magnet
It is simple in structure and easy to process, and since magnetic material is using center to outer diameter step step-by-step system arrangement, plays poly- magnetic and make
With, magnetic field intensity can be not only improved, also helps and generates the preferable initial magnetic field of the uniformity, the difficulty of reduction later stage compensating of the earth magnetic field
Degree, in the case where reaching same magnetic field intensity, can be used less magnetic material, and then can effectively reduce cost.
Description of the drawings
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technology description to be briefly described, it should be apparent that, the accompanying drawings in the following description is the present invention
Some embodiments for those of ordinary skill in the art without creative efforts, can also basis
These attached drawings obtain other attached drawings.
Fig. 1 is one of prior art magnet schematic device；
Fig. 2A is one of permanent-magnet side view of the embodiment of the present invention；
Fig. 2 B are the two of permanent-magnet side view of the embodiment of the present invention；
Fig. 2 C are the three of permanent-magnet side view of the embodiment of the present invention；
Fig. 3 A are one of permanent-magnet vertical view of the embodiment of the present invention；
Fig. 3 B are the two of permanent-magnet vertical view of the embodiment of the present invention；
Fig. 3 C are the three of permanent-magnet vertical view of the embodiment of the present invention；
Fig. 4 A are one of the magnet apparatus that the embodiment of the present invention is used for MRI system；
Fig. 4 B are the two of the magnet apparatus that the embodiment of the present invention is used for MRI system；
Fig. 4 C are the three of the magnet apparatus that the embodiment of the present invention is used for MRI system；
Fig. 5 A are the four of the magnet apparatus that the embodiment of the present invention is used for MRI system；
Fig. 5 B are the five of the magnet apparatus that the embodiment of the present invention is used for MRI system；
Fig. 5 C are the six of the magnet apparatus that the embodiment of the present invention is used for MRI system；
Fig. 6 A are the first column leak stopping magnet ring schematic diagram of the embodiment of the present invention；
Fig. 6 B are the second column leak stopping magnet ring schematic diagram of the embodiment of the present invention；
Fig. 7 is the seven of the magnet apparatus that the embodiment of the present invention is used for MRI system；
Fig. 8 A are one of pole plate schematic diagram of the embodiment of the present invention；
Fig. 8 B are the two of pole plate schematic diagram of the embodiment of the present invention；
Fig. 9 A are the magnetic line of force schematic diagram of the prior art one；
Fig. 9 B are one of magnetic line of force schematic diagram of the embodiment of the present invention；
Fig. 9 C are the two of magnetic line of force schematic diagram of the embodiment of the present invention.
Specific implementation mode
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art
The every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.
It is permanent-magnet side view provided in an embodiment of the present invention referring to Fig. 2A, Fig. 2 B and Fig. 2 C.The permanent-magnet packet
It includes：The column inner magnet 2 made of permanent-magnet material, the first column side magnet 3 and the second column side magnet 4.Wherein, the column
Inner magnet 2, first column side magnet 3 can be selected existing with permanent-magnet material used by second column side magnet 4
Any permanent-magnet material, such as sintered NdFeB, bonding rare earth permanent magnet, Rare-Earth Cobalt, permanent magnetic ferrites etc., be with high energy product
It is excellent.
Wherein, first column side magnet 3 is co-axially located at the outside of the column inner magnet 2, second column
Side magnet 4 is co-axially located at the outside of first column side magnet 3, the column inner magnet 2, first column side magnet
3 concave curved surfaces approximate with all or part of different and formation of the height of second column side magnet 4, the column inner magnet 2
The direction of magnetization be axial, the direction of magnetization of first column side magnet 3 and the axial direction are at first angle a, described second
The direction of magnetization of column side magnet 4 is with the axial direction at second angle b.
In embodiments of the present invention, the column inner magnet 2, first column side magnet 3 and second column side
The height of magnet 4 is all or part of different and forms approximate concave curved surface.There are following three kinds for the height of these three cylindrical magnets
Mode：
Mode 1, referring to one of permanent-magnet side view shown in Fig. 2A, the column inner magnet 2, first column side
Magnet 3 and the height of second column side magnet 4 are incremented by successively.
Mode 2, referring to two of permanent-magnet side view shown in Fig. 2 B, the column inner magnet 2 and first column
The height of side magnet 3 is equal, and the height of second column side magnet 4 is more than the column inner magnet 2 and first column
The height of side magnet 3.
Mode 3, referring to the three of permanent-magnet side view shown in fig. 2 C, first column side magnet 3 and described second
The height of column side magnet 4 is equal, and the height of the column inner magnet 2 is less than first column side magnet 3 and described second
The height of column side magnet 4.
In fig. 2, vertical dotted line indicates that axis, arrow direction indicate the direction of magnetization.When the magnetization side of column inner magnet 2
To for axially upwards when, the direction of magnetization of the first column side magnet 3 and the second column side magnet 4 is directed to column inner magnet 2
The direction of magnetization (left figure in Fig. 2A).When the direction of magnetization of column inner magnet 2 is axially downwardly, the first column side magnet 3 and the
The direction of magnetization of two column side magnets 4 deviates from the direction of magnetization (right figure in Fig. 2A) of column inner magnet 2.Wherein, described second
(the i.e. described second angle b) is big for angle between the direction of magnetization of column side magnet 4 and the direction of magnetization of the column inner magnet 2
In or equal to angle between the direction of magnetization and the direction of magnetization of the column inner magnet 2 of first column side magnet 3 (i.e.
The first angle a), further, the first angle a and second angle b are no more than 30 degree.In Fig. 2 B and Fig. 2 C
In, the direction of magnetization of each magnet is consistent with Fig. 2A, and details are not described herein.
In embodiments of the present invention, the column inner magnet 2 is spliced by section for rectangular multiple magnetic patch approximate solid
Cylinder forms, and first column side magnet 3 is spliced into approximate hollow cylinder for rectangular multiple magnetic patch by section and forms, described
Second column side magnet 4 is spliced into approximate hollow cylinder for rectangular multiple magnetic patch by section and forms, wherein magnetic in the column
The outer surface of body 2 and the inner surface of first column side magnet 3 fit closely, the outer surface of first column side magnet 3
It is fitted closely with the inner surface of second column side magnet 4.Referring to one of permanent-magnet vertical view shown in Fig. 3 A, the column
Shape inner magnet 2, first column side magnet 3 and second column side magnet 4 are the magnetic being square by multiple sections
Block forms, naturally it is also possible to use section to be formed for rectangular magnetic patch, or use the section to be with section for rectangular magnetic patch
The magnetic patch composition of square.In addition, a ring or more can be used with second column side magnet 4 in first column side magnet 3
The magnetic patch arrangement mode of ring, for example in Fig. 3 A, first column side magnet 3 is with second column side magnet 4 respectively by two
A magnetic patch ring composition.
In embodiments of the present invention, it is that rectangular multiple magnetic patch are spliced that second column side magnet 4, which is by section,
And it is spliced near cylindrical, there are following three kinds of connecting methods：
1, referring to two of permanent-magnet vertical view shown in Fig. 3 B, it is assumed that each magnetic patch shown in Fig. 3 B is that section is just
Rectangular magnetic patch, herein under the premise of, if the magnetic patch that all magnetic patch, which are section, to be square, second column side magnet 4
Peripheral magnetic patch only include the magnetic patch that is square of section；
1, referring to two of permanent-magnet vertical view shown in Fig. 3 B, it is assumed that each magnetic patch shown in Fig. 3 B is that section is length
Rectangular magnetic patch, herein under the premise of, if all magnetic patch be section be rectangular magnetic patch, second column side magnet 4
Peripheral magnetic patch only include section be rectangular magnetic patch；
2, referring to three of permanent-magnet vertical view shown in Fig. 3 C, the peripheral magnetic patch of second column side magnet 4 includes
The magnetic patch and section that section is square are rectangular magnetic patch, and it is just that each magnetic patch other than the periphery magnetic patch, which is section,
Rectangular magnetic patch.
It is understood that since magnetic material is the column for being arranged in cross section approximate circle shape for rectangular small magnetic patch by section
Body, and magnetic patch and/or half square magnetic patch arrangement are square using section for the ease of processing and assembling, special-shaped magnetic can be reduced
Block reduces difficulty of processing and expense.
Permanent-magnet provided in an embodiment of the present invention, the permanent-magnet include the column inner magnet made of permanent-magnet material,
First column side magnet and the second column side magnet, column inner magnet, the first column side magnet and the second column side magnet height
Degree is all or part of different and forms approximate concave curved surface.As it can be seen that the magnet structure is simple and easy to process, and due to magnetic material
It is arranged using center to outer diameter step step-by-step system, plays magnet accumulating cap, can not only improve magnetic field intensity, also help
The preferable initial magnetic field of the uniformity is generated, the difficulty for reducing later stage compensating of the earth magnetic field can in the case where reaching same magnetic field intensity
Using less magnetic material, and then can effectively reduce cost.
It is the magnet apparatus provided in an embodiment of the present invention for MRI system, the magnetic referring to Fig. 4 and Fig. 5
Body device includes：Yoke 1, the first main magnet of 1 inner surface top of yoke setting, the setting of 1 inner surface lower part of the yoke
The second main magnet, the first pole plate for being coaxially disposed respectively on first main magnet and the second main magnet apparent surface
51 and second pole plate 52.
Wherein, first main magnet and second main magnet are above-described embodiment introduction by column inner magnet 2, the
The permanent-magnet of one column side magnet 3 and the second column side magnet 4 composition.Wherein, the column inner magnet 2 of first main magnet
The direction of magnetization be axially upwards, the magnetization side of the first column side magnet 3 and the second column side magnet 4 of first main magnet
To the direction of magnetization for the column inner magnet 2 for deviating from first main magnet；The magnetic of the column inner magnet 2 of second main magnet
It is axially upwards that the direction of magnetization of the first column side magnet 3 and the second column side magnet 4 of second main magnet is equal to change direction
It is directed toward the direction of magnetization of the column inner magnet 2 of second main magnet.The direction of magnetization of first main magnet is axial diverging direction,
The direction of magnetization of second main magnet is axially to gather direction, the direction of magnetization of the direction of magnetization of the first main magnet and the second main magnet
Form loop.
In embodiments of the present invention, there are two mounting means with second pole plate 52 for first pole plate 51：
Mode 1, when the height of column inner magnet 2, the first column side magnet 3 and the second column side magnet 4 is incremented by successively
(referring to one of the magnet apparatus for being used for MRI system shown in Fig. 4 A)；Alternatively, working as column inner magnet 2 and the first column
The height of shape side magnet 3 is equal and the height of the second column side magnet 4 is more than column inner magnet 2 and the first column side magnet 3
(referring to the two of the magnet apparatus for being used for MRI system shown in Fig. 4 B) when height；Alternatively, when the first column side magnetic
Body 3 is equal with the height of second column side magnet 4 and the height of column inner magnet 2 is less than the first column side magnet 3 and institute
(referring to the three of the magnet apparatus for being used for MRI system shown in Fig. 4 C) when stating the height of the second column side magnet 4.
In these three cases, the outer diameter phase of the diameter of first pole plate 51 and the second column side magnet 4 of first main magnet
Deng, and first pole plate 51 fits closely first main magnet side with first main magnet, i.e., described first
The side approximation convex surface of pole plate 51 is fitted closely with the approximate concave curved surface of first main magnet；Second pole plate 52
Diameter it is equal with the outer diameter of the second column side magnet 4 of second main magnet, second pole plate 52 to described second
Main magnet side is fitted closely with second main magnet, i.e. the side approximation convex surface of second pole plate 52 and described the
The approximate concave curved surface of two main magnets fits closely.
Mode 2, when the height of column inner magnet 2, the first column side magnet 3 and the second column side magnet 4 is incremented by successively
(referring to the four of the magnet apparatus for being used for MRI system shown in Fig. 5 A)；Alternatively, when the first column side magnet 3 and institute
State the second column side magnet 4 height is equal and the height of column inner magnet 2 is less than the first column side magnet 3 and described second
(referring to the five of the magnet apparatus for being used for MRI system shown in Fig. 5 B) when the height of column side magnet 4.This two
In the case of kind, the diameter of first pole plate 51 is equal with the outer diameter of the first column side magnet 3 of first main magnet, described
First pole plate 51 fits closely first main magnet side and first main magnet, i.e. the one of first pole plate 51
Side approximation convex surface is fitted closely with the approximate concave curved surface of first main magnet；The diameter of second pole plate 52 and institute
The outer diameter for stating the first column side magnet 3 of the second main magnet is equal, second pole plate 52 to second main magnet side
It is fitted closely with second main magnet, i.e. the side approximation convex surface of second pole plate 52 and second main magnet
Approximate concave curved surface fits closely.
When column inner magnet 2 is equal with the height of the first column side magnet 3 and the height of the second column side magnet 4 is more than
(referring to the magnet for being used for MRI system shown in Fig. 5 C when the height of column inner magnet 2 and the first column side magnet 3
The six of device), in this case, the first column side magnet 3 of the diameter of first pole plate 51 and first main magnet
Outer diameter it is equal, first pole plate 51 fits closely first main magnet side and first main magnet, i.e. institute
A side plane of the first pole plate 51 is stated to put down with what the column inner magnet 2 of first main magnet and the first column side magnet 3 were formed
Face fits closely；The diameter of second pole plate 52 is equal with the outer diameter of the first column side magnet 3 of second main magnet, institute
State being fitted closely to second main magnet side and second main magnet for the second pole plate 52, i.e. second pole plate 52
The plane that one side plane is formed with the column inner magnet 2 of second main magnet and the first column side magnet 3 fits closely.
As it can be seen that 51 and second structure that this center is thick, periphery is thin of pole plate 52 of above-mentioned first pole plate, plays poly- magnetic and makees
With, and can effective uniform imaging area magnetic field, obtain a preferable basic magnetic field.
Further, the embodiment of the present invention still further comprises the column leak stopping magnet ring for preventing flux leakage, needs
Illustrate, width (i.e. the difference of the outer diameter of the ring and internal diameter) needs of leak stopping magnet ring are obtained by calculation, cannot be wide or narrow；
Leak stopping magnet ring is wide, can effectively prevent flux leakage, increases magnetic field intensity, but can reduce uniformity of magnetic field；Leak stopping magnet ring mistake
It is narrow, it not can effectively prevent flux leakage not only, magnetic field intensity caused to reduce, can also reduce uniformity of magnetic field.The tool of leak stopping magnet ring
Body structure is as follows：
(referring to Fig. 4 A, Fig. 4 B and Fig. 4 C) under the pole plate mounting means of aforesaid way 1, the magnet apparatus can also wrap
It includes：It is coaxially disposed respectively in the first column leak stopping magnet ring 61 on first pole plate 51 and 52 apparent surface of the second pole plate
With the second column leak stopping magnet ring 62；The outer diameter of the first column leak stopping magnet ring 62 and the second column side of first main magnet
The outer diameter of magnet 4 is equal, the outer diameter of the second column leak stopping magnet ring 62 and the second column side magnet 4 of second main magnet
Outer diameter it is equal.
(referring to Fig. 5 A, Fig. 5 B and Fig. 5 C) under the pole plate mounting means of aforesaid way 2, the magnet apparatus can also wrap
It includes：It is coaxially disposed respectively in the second column side of the second column side magnet 4 and second main magnet of first main magnet
The first column leak stopping magnet ring 61 on 4 apparent surface of magnet and the second column leak stopping magnet ring 62；The first column leak stopping magnet ring
61 outer diameter is equal with the outer diameter of the second column side magnet 4 of first main magnet, the second column leak stopping magnet ring 62
Outer diameter is equal with the outer diameter of the second column side magnet 4 of second main magnet.
Wherein, the first column leak stopping magnet ring 61 is made of at least two first leak stopping magnetic patch, and second column is stifled
Leakage field ring 62 is made of at least two second leak stopping magnetic patch.It is described referring to the first column leak stopping magnet ring schematic diagram shown in Fig. 6 A
First column leak stopping magnet ring 61 is stifled by 12 pieces of (also can be divided into the even numbered blocks such as 24 pieces or other numbers, do not limit herein) first
Magnetic flux leakage block forms, and the first leak stopping magnetic patch may be used permanent-magnet material or use ferromagnetic material, when the first leak stopping magnetic patch
When using permanent-magnet material, the direction of magnetization of the first leak stopping magnetic patch radially outward, i.e., the direction of magnetization of the first leak stopping magnetic patch with
It is axially vertical and diverge in the center of circle；Referring to the second column leak stopping magnet ring schematic diagram shown in Fig. 6 B, the second column leak stopping magnetic
Ring 62 is made of 12 pieces of (also can be divided into the even numbered blocks such as 24 pieces or other numbers, do not limit herein) second leak stopping magnetic patch, institute
It states the second leak stopping magnetic patch permanent-magnet material may be used or use ferromagnetic material, when the second leak stopping magnetic patch uses permanent-magnet material
When, the direction of magnetization of the second leak stopping magnetic patch radially-inwardly, i.e., the direction of magnetization of the second leak stopping magnetic patch with it is axially vertical and be in
Annular shape gathers and the center of circle.
It should be noted that the first column leak stopping magnet ring 61 and blocking up included by the second column leak stopping magnet ring 62
Magnetic flux leakage block number is equal.
Further, due to the assembly relative difficulty of leak stopping magnetic patch, so, for magnet apparatus shown in Fig. 5 (Fig. 5 A, figure
5B and Fig. 5 C), it can not use the first column leak stopping magnet ring 61 and the second column leak stopping magnet ring 62, but by the of the first main magnet
Two column side magnets 4 extend to the position of the first column leak stopping magnet ring 61 and prolong the second column side magnet 4 of the second main magnet
The long position (the seven of the magnet apparatus for MRI system as shown in Figure 7) to the second column leak stopping magnet ring 62.
Mode shown in Fig. 7 also plays the role of preventing flux leakage possessed by leak stopping magnetic patch and is easy installation.
In embodiments of the present invention, horizontal plane form may be used to air side in stepped ramp type pole plate, i.e., described first pole
Plate 61 and second pole plate 62 are plane (one of pole plate schematic diagram as shown in Figure 8 A), stepped ramp type pole to air side
Air side also can be used pole-face with groove in plate, i.e., first pole plate 61 has one respectively to the symmetric position of air side
Groove, second pole plate 62 to the symmetric position of air side have respectively a groove (pole plate schematic diagram as shown in Figure 8 B it
Two).In view of easy to process and later stage shimming problem, using groove type pole plate come approximate saddle-shaped configuration, can reach preliminary equal
The effect of even main field, the effect of the specific initial uniform degree for improving main field.
The magnetic field intensity and uniformity of magnetic field that existing magnet apparatus is provided with magnet apparatus of the present invention below compare.
When using magnet apparatus shown in Fig. 1, referring to existing magnetic line of force schematic diagram, the central part magnetic line of force shown in Fig. 9 A
To be parallel, the both sides magnetic line of force illustrates that the magnetic field intensity of both sides field region is less than the magnetic of central area for arc and to external diffusion
Field intensity, and uniformity of magnetic field is poor (magnetic field intensity difference is larger).
When using magnet apparatus of the present invention (not including leak stopping magnetic patch), illustrate referring to the magnetic line of force of the present invention shown in Fig. 9 B
One of figure, the direction of magnetization of central part magnetic material be vertically upward, the direction of magnetization of lower part both sides magnetic material be inwardly and with it is vertical
Direction there are angle, the direction of magnetization of top both sides magnetic material be outward and with vertical direction there are angle, upper and lower both sides magnetic material
The direction of magnetization is with vertical in the same angle number of degrees.As can be seen that the both sides Fig. 9 B magnetic line of force radian (irises out position in figure from Fig. 9 B
Set) it is less than the both sides Fig. 9 A magnetic line of force radian, and Fig. 9 B magnetic lines of force depth of parallelisms, also superior to Fig. 9 A, this illustrates uniformity of magnetic field
It improves.In addition, since the direction of magnetization of both sides magnetic material is different and magnet structure is in approximate concave curved surface so that the magnetic field of Fig. 9 B is strong
Spend the magnetic field intensity also above Fig. 9 A.
When using magnet apparatus of the present invention (including leak stopping magnetic patch), referring to magnetic line of force schematic diagram of the present invention shown in Fig. 9 C
Two, due to increasing leak stopping magnetic patch, leak stopping magnetic patch can be that ferrimagnet may be permanent-magnet material, and effect can be uniform
Target area magnetic field.It can be seen that leak stopping magnetic patch shrinks back the magnetic line of force extended out partly (to have irised out position in figure from Fig. 9 C
Set), compared with Fig. 9 B, further improve the uniformity of magnetic field of target area.Further, although leak stopping magnetic patch can will extend out
The magnetic line of force to central reduction so that uniformity of magnetic field is promoted, but to avoid that the magnetic line of force is excessive to central reduction, is used
Opening reeded pole plate can make the magnetic line of force being retracted to extending out to a certain extent, can make more magnetic lines of force and axis in this way
Line keeping parallelism, to further increase uniformity of magnetic field.
When using magnet apparatus provided in an embodiment of the present invention, since leakage field is inhibited comprehensively, the magnetic of permanent-magnet material
Efficiency is given full play to, can magnet openness is constant, magnetic material gross weight maintaining so compared with existing magnet apparatus
In the case that substantially constant, magnet gross weight and appearance and size are basically unchanged, magnet yard is substantially improved by force.
In addition, magnet apparatus provided in an embodiment of the present invention has preferable assembling capacity, it is more advantageous to Project Realization, and by
In magnetic material using center to outer diameter step step-by-step system arrange and pole plate setting it is fluted, be more advantageous to generate the uniformity compared with
Good initial magnetic field reduces the difficulty of later stage compensating of the earth magnetic field.In the case where reaching same main field strength, can be used less
Magnetic material, and then can effectively reduce cost, improve magnetic material service efficiency.
The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention.
Various modifications to these embodiments will be apparent to those skilled in the art, as defined herein
General Principle can be realized in other embodiments without departing from the spirit or scope of the present invention.Therefore, of the invention
It is not intended to be limited to the embodiments shown herein, and is to fit to and the principles and novel features disclosed herein phase one
The widest range caused.
Claims (11)
1. a kind of magnet apparatus for MRI system, which is characterized in that including：Yoke, the yoke inner surface
First main magnet of top setting, is coaxially disposed respectively in described the second main magnet of yoke inner surface lower part setting
The first pole plate and the second pole plate on one main magnet and the second main magnet apparent surface and for preventing flux leakage
Column leak stopping magnet ring；
First main magnet is respectively included with second main magnet：The column inner magnet made of permanent-magnet material, the first column
Shape side magnet and the second column side magnet；First column side magnet is co-axially located at the outside of the column inner magnet, institute
State the outside that the second column side magnet is co-axially located at first column side magnet, the column inner magnet, first column
The approximate concave curved surface of all or part of different and formation of the height of shape side magnet and second column side magnet, in the column
The direction of magnetization of magnet is axial, and the direction of magnetization of first column side magnet and the axial direction are at first angle, described the
For the direction of magnetization of two column side magnets with the axial direction at second angle, the second angle is greater than or equal to described first jiao
Degree；
The direction of magnetization of the column inner magnet of first main magnet is the first column side of first main magnet axially upwards
The direction of magnetization of magnet and the second column side magnet deviates from the direction of magnetization of the column inner magnet of first main magnet；It is described
The direction of magnetization of the column inner magnet of second main magnet is the first column side magnet of second main magnet and the axially upwards
The direction of magnetization of two column side magnets is directed to the direction of magnetization of the column inner magnet of second main magnet.
2. magnet apparatus according to claim 1, which is characterized in that
The diameter of first pole plate is equal with the outer diameter of the second column side magnet of first main magnet, first pole plate
First main magnet side and first main magnet are fitted closely；
The diameter of second pole plate is equal with the outer diameter of the second column side magnet of second main magnet, second pole plate
Second main magnet side and second main magnet are fitted closely.
3. magnet apparatus according to claim 1, which is characterized in that
The diameter of first pole plate is equal with the outer diameter of the first column side magnet of first main magnet, first pole plate
First main magnet side and first main magnet are fitted closely；
The diameter of second pole plate is equal with the outer diameter of the first column side magnet of second main magnet, second pole plate
Second main magnet side and second main magnet are fitted closely.
4. magnet apparatus according to claim 2, which is characterized in that the magnet apparatus further includes：It is coaxially disposed respectively
The first column leak stopping magnet ring and the second column leak stopping magnet ring on first pole plate and the second pole plate apparent surface；Institute
The outer diameter for stating the first column leak stopping magnet ring is equal with the outer diameter of the second column side magnet of first main magnet, second column
The outer diameter of shape leak stopping magnet ring is equal with the outer diameter of the second column side magnet of second main magnet.
5. magnet apparatus according to claim 3, which is characterized in that the magnet apparatus further includes：It is coaxially disposed respectively
In on the second column side magnet of first main magnet and the second column side magnet apparent surface of second main magnet
First column leak stopping magnet ring and the second column leak stopping magnet ring；The outer diameter of the first column leak stopping magnet ring and first main magnet
The second column side magnet outer diameter it is equal, the second column of the outer diameter and second main magnet of the second column leak stopping magnet ring
The outer diameter of shape side magnet is equal.
6. magnet apparatus according to claim 4 or 5, which is characterized in that
The first column leak stopping magnet ring is made of at least two first leak stopping magnetic patch, and the first leak stopping magnetic patch uses permanent magnetism material
Material or ferromagnetic material, when the first leak stopping magnetic patch uses permanent-magnet material, the direction of magnetization of the first leak stopping magnetic patch is diameter
To outside；
The second column leak stopping magnet ring is made of at least two second leak stopping magnetic patch, and the second leak stopping magnetic patch is used using forever
Magnetic material or ferromagnetic material, when the second leak stopping magnetic patch uses permanent-magnet material, the direction of magnetization of the second leak stopping magnetic patch
For radially-inwardly.
7. according to claim 2 to 5 any one of them magnet apparatus, which is characterized in that
First pole plate and second pole plate are plane to air side；
Alternatively, first pole plate has a groove respectively to the symmetric position of air side, second pole plate is to air side
Symmetric position have a groove respectively.
8. magnet apparatus according to claim 1, which is characterized in that the column inner magnet is rectangular multiple by section
Magnetic patch is spliced into approximate solid cylinder and forms, and first column side magnet is that rectangular multiple magnetic patch are spliced into approximation by section
Hollow cylinder forms, and second column side magnet is spliced into approximate hollow cylinder for rectangular multiple magnetic patch by section and forms；
The outer surface of the column inner magnet and the inner surface of first column side magnet fit closely, first column side magnet
Outer surface and the inner surface of second column side magnet fit closely.
9. magnet apparatus according to claim 8, which is characterized in that the peripheral magnetic patch of second column side magnet includes
The magnetic patch and/or section that section is square are rectangular magnetic patch.
10. magnet apparatus according to claim 1, which is characterized in that
The column inner magnet, first column side magnet and the height of second column side magnet are incremented by successively；
Alternatively, the column inner magnet is equal with the height of first column side magnet, the height of second column side magnet
Height of the degree more than first column side magnet；
Alternatively, first column side magnet is equal with the height of second column side magnet, the height of the column inner magnet
Height of the degree less than first column side magnet.
11. magnet apparatus according to claim 1, which is characterized in that the first angle does not surpass with the second angle
Cross 30 degree.
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| CN201510920040.2A CN105390229B (en) | 2015-12-10 | 2015-12-10 | A kind of permanent-magnet and the magnet apparatus for MRI system |
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| CN201510920040.2A CN105390229B (en) | 2015-12-10 | 2015-12-10 | A kind of permanent-magnet and the magnet apparatus for MRI system |
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| CN105390229B true CN105390229B (en) | 2018-11-06 |
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