A method for manufacturing a laminated body includes: laminating an electromagnetic steel plate to form the laminated body; performing an annealing process on the laminated body; acquiring a before-annealing lamination thickness information on a thickness of the laminated body before performing the annealing process on the laminated body; and when the before-annealing lamination thickness information does not satisfy a before-annealing criterion which is predetermined, adjusting a lamination condition of the electromagnetic steel plate such that the before-annealing lamination thickness information satisfies the before-annealing criterion.

A motor-generator utilizes a multi-part rotor encircling a stator, the rotor including a plurality of rotor segments.

A method of resin sealing a permanent magnet in a magnet insertion portion of a laminated body, the body formed by laminating plural core sheets and including the plural portions formed around a shaft hole in a center of the plural portions, the portion connected to an internal space via an opening. The method includes a first process of positioning a blocking member blocking the opening from a side of the space in a way that the member is vertically-placed in a lower die or an upper die, while the both dies hold the body from both sides in an axial direction and close the portion; and a second process of filling a resin extruded from a resin reservoir portion provided in the die or the die into the portion having the magnet inserted and having the opening closed by the member.

A rotor for an electrical machine includes a laminated core having a main axis and a plurality of poles delimiting a plurality of radial seats extending along the main axis, each seat being delimited by a first and a second pole. The rotor includes a plurality of magnets inserted in the seats and a plurality of springs locking the magnets in the seats; the springs acting between each magnet and the first pole delimiting the relative seat for pushing each magnet towards the second pole delimiting the same seat.

An electric motor and a compressor having an electric motor. The electric motor may include a stator, and a rotor provided with a rotational shaft, a rotor core coupled to the rotational shaft, and permanent magnets coupled to the rotor core. The rotor core may include a first core to which the permanent magnets may be coupled, and a second core made of a magnetic material and coupled to an end of the first core in an axial direction. The second core may have outer surfaces disposed inside of extension lines extending in the axial direction from inner surfaces of the permanent magnets.

A method of forming a molded rotor assembly for an electric motor includes providing a lamination stack, molding an insulative material to the lamination stack to form an integral fan and magnet retention coupled to the lamination stack, the lamination stack and the integral fan and magnet retention together forming a rotor body, and pressing a shaft into a central aperture formed in the rotor body to achieve an interference fit between the shaft and the lamination stack.

A magnetizing apparatus includes a holding member including a rotor fixing portion for holding a rotor, a coil member including a support plate that is thin plate-shaped and a coil that is incorporated inside the support plate, and a coil fixing portion that is provided to the holding member and arranges and fixes a plurality of coil members radially with respect to the center of the rotor fixing portion.