Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F7/00—Magnets
  • H01F7/02—Permanent magnets [PM]
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
  • H01F41/0273—Imparting anisotropy
  • H01F41/028—Radial anisotropy
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F7/00—Magnets
  • H01F7/02—Permanent magnets [PM]
  • H01F7/0205—Magnetic circuits with PM in general
  • H01F7/021—Construction of PM
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K15/00—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines
  • H02K15/02—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies
  • H02K15/03—Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing of dynamo-electric machines of stator or rotor bodies having permanent magnets

Definitions

• This invention is concerned with a cylinder type anisotropic magnet that can enhance total magnetic flux which is generated from the magnetic pole surface and the improvement of cogging characteristicson motors; furthermore, it is used for two pole motors, and by efficiently placing cylinder type anisotropic magnets in which a specified range is radial anisotropic and the rest is orthogonal anisotropic (orthogonal)and/or isotropic; thus, motor can achieve efficiency in the assembly work, noise abatement and miniaturization.
• sintered magnets such as ferrite magnet and rare earth magnet and resin-bonded magnet,are known.
• ferrite magnet As magnet used for two pole motor, etc, sintered magnets such as ferrite magnet and rare earth magnet and resin-bonded magnet,are known.
• the motor compositions which utilize ferrite type scinterd magnet (heretofore, referred to as ferrite magnet) as stator and rotor are known.
• the composition which is shown in Fig.8, is an example of a motor in which a cylinder type ferrite magnet 81 is utilized on the stator side. It is fastened on the inner circumference of the cylinder type yoke 82, and at the same time, rotor (not shown) is placed in space 83 of the inner circumference side of the said ferrite magnet 81.
• a cylinder type ferrite magnet 81 is utilized on the stator side. It is fastened on the inner circumference of the cylinder type yoke 82, and at the same time, rotor (not shown) is placed in space 83 of the inner circumference side of the said ferrite magnet 81.
• isotropic cylinder ferrite magnet 81 used for relatively low performance motors.
• the composition shown in Fig.9 is an example of utilizing a pair of segment magnets 81a and 81 b on the stator side. They are fastened to the inner circumference of the cylindrical yoke 82, and at the same time,
• composition shown in Fig. 10 is an example of utilizing a pair of segment magnets 91a and 91 b on the rotor side, and they are fastened to the respective outer circumference of the magnet support 93 which is fastened to a central axle 92, and positioned within the specifically shaped stator (not shown).
• segment magnets 91a and 91b which are similar to the ferrite magnets 81a and 81b as shown in Fig.9, since magnetic radial anisotropic ferrite magnet having excellent magnetic property can be utilized, they are applied to relatively high output motors.
• anisotropic cylinder type ferrite magnet utilized in two pole motors, depending on the orientation of its anisotropy, the radial anisotropic cylinder type ferrite magnet and the orthogonal anisotropic cylinder type ferrite magnet are known.
• the approximately constant magnet flux is maintained at any given position of the circumference in the middle of space between stator and motor, which results in highly efficient motor.
• the magnet materials which possess the identical magnetic characteristic are utilized, it is possible to obtain superior motor output in comparison to the composition which utilizes the orthogoral anisotropic cylinder type ferrite magnet.
• the molded body will crack when sintering, and for all practical purposes, it is difficult to manufacture a unit body radial anisotropic cylinder type ferrite magnet which has the required strong magnetic properties.
• the magnetic characteristics of radial anisotropic cylinder type ferrite magnet which is industrially sintered by this method has the upper limit of Br 3.4 kG, ⁇ Hc 2.9 kG, (BH)max 2.6 MGOe, which is not satisfactory for the demand for higher performance in recent years.
• each type of magnets has some problems associated with it. These problem occur even when the above ferrite magnets are placed on the rotor side of the two pole motor.
• the anisotoripic direction of upper and lower magnets 101 and 102 are aligned in the vertical direction, by being anisotropic magnetized to the direction of magnet thickness; furthermore, right and left permanent magnets 103and 104 are arranged so that the anisotropic direction is right angle to the direction of magnet thickness, and the anisotropic directions of four permanent agnets, 101, 102, 103 and 104 are right angle to the cylinder axis/thus they have the same direction.
• each separately molded permanent magnet has each distinctive magnetic characteristics, and considering those scattering characteristics, they can not necessarily satisfy requirements in the said technical field from the point of cogging prevention.
• the objectives of this invention are concerned with solving problems of the anisotropic magnet with the above composition, and to provide a cylindertype anisotropic magnet which enhances the total magnetic flux generated from magnet poles and improve their motor cogging characteristics. Furthermore, the objectives of this invention are the improvement of the assembly efficiency relative to the motor containing the usual radial anisotropic segment magnets, the increase in the total magnetic flux generated from the magnetic poles relative to the motors which utilize the isotropic cylinder shape ferrite magnet and the orthogoral anisotropic cylinder shape ferrite magnet, and to accomplish miniaturization of the whole motor; furthermore, it is to provide the motor which lowers the noise level by improving cogging characteristicetc. relative to the motors which utilizes the radial anisotropic magnet ferrite magnet and the radial anisotropic cylinder shape ferrite magnet.
• the object of this invention is to provide the motor which has the higher efficiency and the better cogging characteristics relative to the so-called assembly type anisotropic magnet which consists of multiple separately molded permanent magnets. Disclosure of Invention
• This invention provides, as a practical method to manufacture a unit body cylinder shape anisotropic sintered magnet in which a pair of opposite parts have radial anisotropy within a specified angle and the remainder orthogonal anisotropy and/or isotropy, a process for producing them whereby; molding magnetic raw materials powder in the magnetic field in a molding apparatus provides a molding dies which has an elliptical molding space in which a longer diameter of the said molding space is placed in the magnetizing direction between a pair of the magnet poles, a pair of the magnet are placed opposite to the long diameter in said molding space and an core consisting of a magnetic body similarly shaper to the said molding space; sintering the elliptical molded body; thus producing cylindertype anisotropic magnet which consists of a cylindrical unit sintered body in which a pair of opposing parts show radial anisotropy within a specified range, and the rest shows orthrogoral anisotropy and/or isotropy.
• this invented unit body cylinder shape anisotropic resin-bonded magnet the following process is privided; in a molding apparatus privides a molding dies which has an circular molding space between a pair of magnetic poles, a pair of the magnet are placed opposite to the long diameter in said molding space and an core consisting of a magnetic body similarly shaper to the said molding space, after thermal setting resins, coupling agents, and lubricants are added to the magnetic raw materials powder and mixed, it is molded in the magnetic field.
• the room temperature curing or thermal curing method is chosen to produce a unit body cylinder shape anisotropic resin-bonded magnet, in which a pair of opposing parts are radial anisotropic within a specified angle range and the rest is orthogoral anisotropic and/or isotropic.
• ferrite magnets such as a Sr ferrite magnet and a Ba ferrite magnet, etc.
• rare earth magnets such as rare earth-cobait magnets, rare earth-iron-boron magnets, and any other known anisotropic sintered magnets or anisotropic resin-bonded magnets can be utilized.
• Fig.1 shows an example of this invented motor, which shows a plane view explaining a stator parts.
• Fig.2 A and B shows examples of conceptual drawings which explains a cylindershape anisotropic magnet which is placed in this invented motor and its manufacturing apparatus.
• Fig.3 A and B shows other example of conceptual drawings which explains in this invented cylinder shape anisotropic magnet which is placed a motor and its manufacturing apparatus.
• Fig.4 shows other example of conceptual drawings which explains in this invented cylindershape anisotropic magnet which is placed a motor and its manufacturing apparatus.
• Fig.5 shows examples of a plane view explaining manufacturing process of this invented cylinder shaped anisotropic magnet cylinder with other composition which is placed in motor.
• Fig.6 shows other example of this invention; particularly, the plane view drawing explains only the rotor composition.
• Fig.7 shows the graph which is a result of relative measurements of the magnetic flux distribution in the circumferential direction at the center of space between stator and rotor of this invented motor and usual two pole motor.for making the effectiveness of this invented motor clear.
• Fig.8 shows a plane vies which explains a motor composition in which usual ferrite magnets are placed at stator and rotor.
• Fig.9 shows a plane view which explains motor composition in which usual ferrite magnets are placed at stator and rotor.
• Fig.10 shows a plane view which explains a motor composition in which usual ferrite magnets are placed at stator and rotor.
• Fig.11 shows an oblique viewwhich explains the usual brushless motor rotor.
• Fig.12 shows an oblique viewwhich explains the other brushless motor rotor.
• Fig.1 is a plane view of the stator part as an example of this invented motor.
• Fig.1,10 is a ferrite magnet which contains Sr and is obtained from a manufacturing method described later. It is a cylindershape anisotropic ferrite magnet with diameter Dl which consists of a pair of opposing parts 11a and 11b where each has radial anisotropy within the angle range of 01(theta 1) and the parts 12a and 12b of the remainder are orthogoral anisotropic magnets.
• the cylindtrical process is applied after sintering it to the magnet, and it is pressure fastened to a cylinder shape yoke 82 to form stator.
• the Fig.2 — Fig.4 show drawings that describe the said ferrite magnet and the molding apparatus with which to manufacture it.
• the ferrite magnet 10 shown in Fig.2A has a pair of opposing parts 11a and 11b each of which possesses radial anisotropy within the angle range 01(theta 1), and the rest orthogoral anisotropy at parts 12a and 12b and with diameter of Di. M in the figure indicates the magnetizing direction of the molding apparatus which is stated later.
• Fig.3 A and B is an example of the molding apparatus to manufacture the above ferrite magnet 10 That is to say, the apparatus is made by placing a molding dies 3, which has an elliptical molding space in which the magnetizing direction (M direction in the figure) conincides with a longer diameter, between a pair of magnetic poles 1a and 1 b to which magnetic coils 2a and 2b are wound; and at the same time, by placing a pair of magnets 4a and 4b at the outer circumference of the said molding space and opposite parts to the longer diameter direction, placing a pair of non-magnetic bodies 5a and 5b opposite to the shorter diameter direction, and placing core 6 which consists of a magnet body similarly shaped to the said molding space at the center of the said molding space.
• M direction in the figure the magnetizing direction
• individual magnet bodies 4a and 4b are placed opposite to the outer circumference of the angle range 03(theta 3) in the elliptical molding space.
• 8 is the ring shape lower punch which is non ⁇ magnetic
• 9 is the ring shape upper punch which is also non-magnetic.
• the magnetic raw materials powder 7 of a specified composition After insertintg the appropriate amount of the magnetic raw materials powder 7 of a specified composition into the elliptical molding space in the molding dies 3 of the above described molding apparatus, it is compression molded while being magnetized by a pair of magnetic poles along the M direction as shown in the figure by passing the electric current through electomagnetic coils 2a and 2b.
• each opposing part to a pair of magnets 4a and 4b will have radial anisotropy, and each opposing part to a pair of non-magnets 5a and 5b will have orthogonal anisotropy.
• the magnetic field from magnet poles can be effectively applied to the magnetic raw materials powder 7.
• the molded body thus obtained consists an elliptical molded body 20 with a longer diameter D2 and a shorter diameter D3, as shown in B of Fig.2, has a pair of opposing parts 21 a and 21 b, each of which is radial anisotropic within the angle range 02(theta 2), and the reminders 22a and 22b consist, which is orthogonal anisotropic.
• M in the figure is the direction of magnetization in the above molding apparatus.
• this elliptical molded body 20 by sintering this elliptical molded body 20 at a specified temperature, as shown in A of Fig.2 A, it is possible to make it into the cylinder type anisotropic ferrite magnet with almost circular shape in cross section in which a pair of opposing parts 21a and 21b are radial anisotropic within each angle range 02(theta 2), and the reminders 22a and 22b are orthogonal anisotropic.
• Fig.2 barriers between a pair of opposing parts and the rest are shown by the continuous line; however, it does not necessarily indicate, for example ,how radial anisotropy and orthogonal anisotropy clearly changes at the said continuous line. As far as the said remaining part is concerned, it results not only in orthogonal anisotropy, but a part or in some cases all of it could result in isotropy according to the composition of the above molding apparatus and the magnetizing direction of magnetic raw materials powder 7 when pressure molding it.
• the molding space is created without using non ⁇ magnetic bodies 5a and 5b.
• the magnetic characteristics distribution between the radial anisotropic part and the orthogonal anisotoropic and/or isotropic part varies, based on thickness and shape of the butting sede of the above altered magnetic bodies 4a and 4b.
• the reason behind making the molding body 20 into an elliptical shape is due to the differences in the shrinkage rate of the molding body depending on weather it is alined with the magnetization direction or right angle to it when it is pressure molded in the magnetic field. Since the shrinkage rate in the magnetization direction is usually larger, the molding body is made into an elliptical shape so that the magnetization direction aligns with the longer diameter; and it is made into a cylindershape after sintering to reduce the processing cost in the grinding process, resulting in the increasing the yield, and to lower the cost of manufacturing.
• this molding body 20 are optimized according to its magnetic characteristics together with the shape and measurement of the cylindertype an isotropic ferrite magnet which is finally obtained after sintering; however, usually in the case of cylinder type an isotropic ferrite magnet which is used forthe multi purpose two pole motor, the ratio of the long diameter D2to the short diameter D3 of the molding body 20, D2/D3, is about 1.05 ⁇ 1.15, and the degree range of radial anisotropy of 100° - 160° is desirable.
• the molding apparatus can be composed the same way.
• the molding apparatus is not limited to the above composition, but many compositions can be implemented.
• the composition must at least have a molding dies which has the elliptical molding space with a longer diameter aligned with the magnetization direction between a pair of magnetic poles, a pair of magnetic bodies in the opposite parts of the longer diameter direction of the said molding space, and a core which consists of a magnetic body similar shaped to the molding space at the center of the molding space.
• the molded body is obtained by making the molding space cylindrical as in the apparatus in Fig.3, the said molded body becomes a cylindrical molded body 40, in which a pair of opposing parts 41 a and 41 b each of which has anisotropy within the angle rage 02(theta 2), and the remainder parts 42a and 42b have orthogonal anisotropy.
• M is the magnetization direction of the above molding apparatus.
• this cylindrical molded body 40 when it is sintered at a specified temperature, it produces an elliptical sintered body 50 with a long diameter D2 and a short diameter D3 in which a pair of opposing parts 51a and 51 b each of which has radial anisotropy within the angle range thetai as in Fig.5 B, and the remainder parts 52a and 52b have orthogonal anisotropy.
• M in the figure is the magnetizaiton direction of the above molding apparatus. Then, by administering the inner diameter processing and the exterior diameter processing (the oblique line area in the figure is eliminated) to the internal circumference parts 53a and 53b and outer circumference parts 54a and 54b, respectively, of this elliptical sintered body 50.
• a cylindertype anisotropic ferrite magnet shaped almost circle longitudinal section is obtained.
• the magnet has a pair of opposing parts 61a and 61b each of which has radial anisotropy within the angle range thetai, and the remainder parts 62a and 62b have orthogonal anisotropy.
• the inner circumference surface 63a and 63b of the radial anisotropic parts 61a and 61b is mechanically finished into a cylindrical shape by the above inner diameter processing, but the inner circumference surface 64a and 64b of the orthogonal anisotropic parts 62a and 62b are not eliminated by the inner diameter processing and maintain the sintered surface condition.
• the change in the magnetic flux distribution as it moves from the radial anisotropic parts 61a and 61b to the orthogonal anisotropic parts 62a and 62b become smooth, which improves the motor cogging characteristics.
• the shape of the above molded body into an elliptical shape in which a longer diameter aligns with the magnetization direction for the outer diameter, and making the inner diameter cylindrical, the sintered body in which the outer diameter cylindrical and the inner diameter elliptical.
• Fig.6 shows the other example of this invention, particularly, it shows only the rotor composition of the motor. That is to say that, 70 of Fig.6 is a cylinder type anisotropic ferrite magnet which is obtained by the above manufacturing, method, in which a pair of opposing parts 71a and 71b each of which has radial anisotropy within the angle range thetai, and the remainder parts 72a and 72b have orthogonal anisotropy.
• the cylindrical processing is applied after sintering, a rotor axis 92 is fastened to the outer circumference of the magnet support 93 at the center, and it is placed within the stator (not shown) with a specified shape to compose the motor.
• the technology which is utilized forthe above stator composition can also be applied to a cylindertype anisotropic ferrite magnet 70.
• the shape of molded body shape can be cylindrical.
• the molding apparatus is made by placing a molding dies which has a cylindrical molding space between a pair of magnetic poles, placing a pair of magnetic bodies opposite to the magnetic poles of the magnetic body similarly shaped to the said molding space, and placing a core which consists of the said molding space at the center of the molding space.
• Thermal setting resins, coupling agents,and lubricants are added to the magnetic raw materials powder placed in the molding apparatus in presence of the magnetic field; furthermore, the room temperature curing or the thermal curing can be applied based on the binder utilized.
• thermosetting resins after pressure molding the magnetic powder, after it is heat treated if needed, and it is impregnated with thermosetting resins.
• the filling rate of magnetic powder in the resin-bonded magnet can be optimized according to the above manufacturing method.
• Synthetic resins used as binder can be either of thermosetting or thermoplastic; however, it is preferable to choose thermally stable resins, and it can be optimally selected from, for example, polyamid, polyimid, phenol resins, flouride resins, silicon resins, and epoxy resins.
• Example 1 utilizing the identical magnetic raw materials powder as above, and a cylindertype arthogonal anisotropic sintered magnet with an outer diameter 40mm . x an inner diameter 30mm x a height 10mm was obtained; by usual method by placing the magnet in the same direction as this invented motor, the identical measurement with Example 1 was made.
• the cylindertype radial anisotropic sintered magnet was obtained.
• the magnet has dimensions of an outer diameter 40mm x an inner diameter 30mm x a height 10mm and which is known to have the excellent magnetic characteristics within the range where the cracking does not occur when sintered.
• Fig.7 shows various magnetic flux distribution
• the horizontal axis in Fig.7 indicates the measurement angle (degree ° ), and the vertical axis indicates the magnetic flux density Bg(kG) at individual positions.
• the magnetic flux which is generated from the magnetic poles, namely the area surrounding the horizontal axis of the graph representing magneticflux and the magneticf lux distribution curve since a part of this invented magnet is radial anisotropic, is clearly largerthan that of the comparative example 1 Therefore, it is possible to increase the motor output.
• the this invention can be better manufactured without cracking even if it made from the high performing raw materials than the magnet of the comparative example 2 plotted by x mark, the magneticflux which is generated from the magnetic pole surface is greater than the comparative example 2; and it has the good cogging characteristics.
• this invented motor has the same level of noises generated from cogging as in the motor of the comparative example 1 ; however, it was confirmed that the revolution torque improved 15% — 20% as the total magnetic flux generated from the magnet increased, Therefore, the relative reduction of noises was accomplished, since the increase in the revolution torque does not increase noises generated from cogging.
• noises generated from cogging in this invented motor is reduced 50% — 60% compared to the motor in the comparative example 2; and it was confirmed that the revolution torque improved 20% - 25% as the total magnetic flux generated from the magnet increased.
• This invented motor is concerned with the effective utilization of individual magnet by placing the unit cylinder type anisotropic magnet in which a specified part of it is made radial anisotropic and the remainder made into either orthogonal anisotropic and/or isotropic, and the achieving the enhancement of the motor output which results from the enhancement of the total magneticflux generated from the magnetic poles; and since it improves the cogging characteristics of a motor, it is possible to realize the reduction of noises which generate from the said cogging.
• This invented manufacturing method prevents fractures and cracking from occuring when sintering the cylindertype anisotropic sintered magnet and efficiently mass produce it.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Permanent Field Magnets Of Synchronous Machinery (AREA)
• Manufacturing Cores, Coils, And Magnets (AREA)

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• 1993
  • 1993-04-27 EP EP93909421A patent/EP0591555A1/en not_active Withdrawn
  • 1993-04-27 KR KR1019930704038A patent/KR940701579A/ko not_active Application Discontinuation
  • 1993-04-27 WO PCT/JP1993/000539 patent/WO1993022778A1/en not_active Application Discontinuation
  • 1993-04-27 TW TW082103259A patent/TW231395B/zh not_active IP Right Cessation
  • 1993-04-28 CN CN93106368A patent/CN1086932A/zh active Pending

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