A rotor for a rotary electric machine and having: a plurality of permanent magnets, which are axially oriented and are arranged beside one another around a rotations axis so as to form a closed ring; a support cylinder, which has an outer surface, on which the permanent magnets rest, and a central cavity; and two half-shafts, which are independent of and separate from one another and are singularly inserted in opposite ends of the central cavity of the support cylinder so as to form one single block with the support cylinder. The permanent magnets are circumferentially arranged one following the other according to a Halbach array so as to nullify the magnetic field radially on the inside of the permanent magnets and so as to maximize the magnetic field radially on the outside of the permanent magnets.

A reciprocating tool includes a motor, a reciprocating member, and a crank mechanism. The motor is disposed in a housing. The reciprocating member projects from the housing. The crank mechanism converts rotation of a rotation shaft of the motor into reciprocation of the reciprocating member. The crank mechanism rotates around an axis in a lateral direction by rotation transmission from the rotation shaft, and the crank mechanism includes a crank member having an eccentric pin, a connecting rod coupling the eccentric pin to the reciprocating member, and a balancer coupled to the eccentric pin, and the balancer is supported by the eccentric pin alone in the housing.

A reciprocating tool includes a motor, a reciprocating member, and a crank mechanism. The motor is disposed in a housing. The reciprocating member projects from the housing. The crank mechanism converts rotation of a rotation shaft of the motor into reciprocation of the reciprocating member. The crank mechanism rotates around an axis in a lateral direction by rotation transmission from the rotation shaft, and the crank mechanism includes a crank member having an eccentric pin, a connecting rod coupling the eccentric pin to the reciprocating member, and a balancer coupled to the eccentric pin, and the balancer is supported by the eccentric pin alone in the housing.

A rotor assembly for a permanent magnet motor includes a rotor stack of laminated ferromagnetic layers and partial end plates at opposite axial ends of the rotor stack wherein each axial end of the rotor bears two partial end plates, each of which covers a partial circle and does not axially overlap with the other one of the partial end plates at the same axial end. The two partial end plates of each axial end are formed by a first axial end plate shaped as a first partial ring disc and a second partial end plate shaped as a second partial ring disc that are made of stamped metal and that are of different mass.

A rotor assembly for a permanent magnet motor includes a rotor stack of laminated ferromagnetic layers and partial end plates at opposite axial ends of the rotor stack wherein each axial end of the rotor bears two partial end plates, each of which covers a partial circle and does not axially overlap with the other one of the partial end plates at the same axial end. The two partial end plates of each axial end are formed by a first axial end plate shaped as a first partial ring disc and a second partial end plate shaped as a second partial ring disc that are made of stamped metal and that are of different mass.

A rotating part that includes at least one generator unit having at least one coil, at least one permanent magnet and two pole shoes having pole surfaces facing radially outward is provided, The non-rotating part has an arc-shaped saddle adaptor of ferromagnetic material arranged with a radial distance to the pole surfaces. The saddle adaptor is configured to close a magnetic circuit passing via the pole shoes through the coil in a rotational position where the saddle adaptor overlaps with the pole shoes of the generator unit.

A rotating part that includes at least one generator unit having at least one coil, at least one permanent magnet and two pole shoes having pole surfaces facing radially outward is provided, The non-rotating part has an arc-shaped saddle adaptor of ferromagnetic material arranged with a radial distance to the pole surfaces. The saddle adaptor is configured to close a magnetic circuit passing via the pole shoes through the coil in a rotational position where the saddle adaptor overlaps with the pole shoes of the generator unit.

A method of assembling an electric motor comprises axially translating a rotor of a rotor assembly in a first direction through a longitudinal bore of a stator, a first centering ring of the rotor assembly preventing a first end of the rotor from contacting an internal surface of the longitudinal bore; rotatably supporting a first end of the rotor assembly longitudinally extending from the rotor with a first support member; resting a second centering ring of the rotor assembly on the internal surface of the longitudinal bore; rotatably supporting a second end of the rotor assembly longitudinally extending from the rotor with a second support member; and axially translating the rotor assembly in a second direction, opposite the first direction, to place the rotor assembly in a position in which both the first centering ring and the second centering ring are outside the longitudinal bore.

The present invention provides a counterweight for a compressor, an electric motor, with the counterweight, for a compressor, and a compressor with the electric motor or the counterweight. The counterweight comprises: a first component having an annular shape; a first groove formed in a surface of the first component and having a sidewall and a bottom wall; and a second component disposed in the first groove. With the technical solution according to the present invention, for example, counterbalance requirements are met, while fluid can be prevented from being stirred to cause power loss.

The present invention provides a counterweight for a compressor, an electric motor, with the counterweight, for a compressor, and a compressor with the electric motor or the counterweight. The counterweight comprises: a first component having an annular shape; a first groove formed in a surface of the first component and having a sidewall and a bottom wall; and a second component disposed in the first groove. With the technical solution according to the present invention, for example, counterbalance requirements are met, while fluid can be prevented from being stirred to cause power loss.