Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
  • H02K1/22—Rotating parts of the magnetic circuit
  • H02K1/27—Rotor cores with permanent magnets
  • H02K1/2706—Inner rotors
  • H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
  • H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
  • H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
  • H02K1/276—Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K1/00—Details of the magnetic circuit
  • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
  • H02K1/22—Rotating parts of the magnetic circuit
  • H02K1/24—Rotor cores with salient poles ; Variable reluctance rotors
  • H02K1/246—Variable reluctance rotors

Definitions

• Permanent magnet rotor for a synchronous electrical machine, particularly for a reluctance motor
• the present invention relates to a rotor for a synchronous electrical machine, particularly for a reluctance motor, provided with permanent magnets.
• the invention relates to a rotor with N poles, where N is an even integer, comprising a stack of plates of magnetic material, each having N adjacent angular sectors, in each of which is formed a corresponding plurality of cavities or apertures, into which there extend corresponding permanent magnetic elements which are magnetized in each sector in the opposite direction to those in the adjacent sectors.
• such a rotor is made by inserting "solid" permanent magnets, for example permanent magnets made from neodymium, iron and boron, into the cavities of its angular sectors.
• One object of the present invention is therefore to propose an alternative method of making a rotor for a synchronous electrical machine, particularly for a reluctance motor, which overcomes the aforementioned problems of the prior art.
• a rotor of the type specified above characterized in that the aforesaid permanent magnetic elements are formed from a magnetic material which is injection moulded in the apertures or cavities of the stack of plates.
• the solution according to the invention enables the permanent magnets to be formed in situ in the cavities in an extremely simple way, even in cases in which continuous or progressive skewing is present in the plates of the rotor stack.
• the permanent magnetic elements can be overmoulded on the rotor plate stack in the presence of a magnetic field such that the magnetic domains of the permanent magnetic elements associated with each sector of the rotor can be orientated in the desired way.
• the magnetic material can be moulded, by injection moulding for example, in the absence of magnetization in the mould, and the desired orientation of the domains can be obtained subsequently, outside the mould, using known types of magnetizing equipment.
• the desired orientation of the domains of the moulded permanent magnetic elements can be obtained by applying a magnetic field in the mould during the injection moulding, and by then carrying out a further magnetization operation after moulding, in a known type of magnetizing equipment.
• Figure 1 is a partial view in cross section of a four-pole rotor made according to the present invention.
• Each of the angular sectors 1-4 has a corresponding plurality of cavities or apertures C capable of forming barriers to the flow of the magnetic flux in the rotor and having a generally curved shape, with the convexity of each curve facing the axis O of the rotor R.
• each of the radially innermost cavities C is interrupted centrally by a corresponding radial link B for structural reinforcement.
• the stack LS of plates L is subjected to a moulding operation, such as injection moulding, by means of which elements M of permanent magnetic material are formed in the apertures or cavities C.
• the moulded magnetic material can be, for example, a plastic-ferrite, or a neodymium-iron-boron-based material in a plastic matrix.
• the cavities C can if necessary be filled completely by the magnetic elements moulded in them.
• the cavities C may be only partially filled with the injection moulded magnetic elements, as shown by way of example in Figure 1.
• the domains of the injection moulded magnetic elements can be orientated within the mould and/or after moulding, in a known type of magnetizing equipment.
• the injection moulded magnetic material can extend at least partially over the outer faces of the terminal plates of the rotor stack LS, in order to improve and reinforce the assembly of this stack, thus facilitating the moulding of the stack.
• the overmoulded magnetic material can subsequently be removed locally in order to improve the balance of the rotor.
• the magnetization of the permanent magnetic elements M is essentially orientated, in a known way, in a radial direction, the direction in each sector being opposite to the direction in the adjacent sectors, as shown in Figure 1 in which the letters N and S indicate the "north" and “south” poles, respectively, of the permanent magnetic elements M.
• the rotor according to the invention is easy to produce, even if progressive or continuous skewing is present in the stack LS of plates L.
• the invention makes it possible to save time in the manufacture of the rotor, and enables a plurality of rotors to be produced simultaneously by using multiple moulds.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Permanent Field Magnets Of Synchronous Machinery (AREA)
• Iron Core Of Rotating Electric Machines (AREA)
• Synchronous Machinery (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=40315009

Family Applications (1)

Country Status (2)

Cited By (11)

Citations (4)

• 2007
  • 2007-11-13 IT IT000809A patent/ITTO20070809A1/it unknown
• 2008
  • 2008-10-29 WO PCT/IB2008/054477 patent/WO2009063350A2/en active Application Filing

Patent Citations (5)

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