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.

In one possible implementation, a motor is provided including a rotor and a stator. Front cooling fins are thermally coupled to a front of the stator, and rear cooling fins are thermally coupled to a rear portion of the stator. The winding is between the front and rear cooling fins.

In one possible implementation, a motor is provided including a rotor and a stator. Front cooling fins are thermally coupled to a front of the stator, and rear cooling fins are thermally coupled to a rear portion of the stator. The winding is between the front and rear cooling fins.

A stator for a rotating electrical machine is disclosed, the stator comprising a plurality of stator slots (22) each of which accommodates a plurality of coils (40) of stator windings (18). Radial air gaps (46) are present between the coils of adjacent stator slots as the coils extend out of the stator slots. Insulating means (42, 54, 84) are provided between the coils of a stator slot as the coils extend out of the stator slot. The radial air gaps (46) are defined between the insulating means of the coils of adjacent stator slots. This can allow radial air passages to be formed through the windings, while ensuring sufficient electrical insulation between the coils of a stator slot.

In an electric power steering device, a motor housing includes an end face part opposite to an output part of a rotating shaft of an electric motor. A power conversion circuit part includes a power conversion switching circuit part, and a second part exclusive of the power conversion switching circuit part. The power conversion switching circuit part includes an upper arm switching element and a lower arm switching element packaged by synthetic resin, and is mounted on a power conversion switching circuit board that is mounted to a power conversion switching circuit part heat dissipation section of the end face part for heat dissipation. A power supply circuit part and the second part of the power conversion circuit part are mounted on a power supply circuit board that is mounted to a power supply circuit part heat dissipation section of the end face part for heat dissipation.

In an electric power steering device, a motor housing includes an end face part opposite to an output part of a rotating shaft of an electric motor. A power conversion circuit part includes a power conversion switching circuit part, and a second part exclusive of the power conversion switching circuit part. The power conversion switching circuit part includes an upper arm switching element and a lower arm switching element packaged by synthetic resin, and is mounted on a power conversion switching circuit board that is mounted to a power conversion switching circuit part heat dissipation section of the end face part for heat dissipation. A power supply circuit part and the second part of the power conversion circuit part are mounted on a power supply circuit board that is mounted to a power supply circuit part heat dissipation section of the end face part for heat dissipation.

In one possible embodiment, an aircraft electric motor cooling system is provided having an airflow path through a spinner which includes a first airflow path between an inner rotor and a stator, a second airflow path between an outer rotor the stator and a third airflow path along an outer surface of the outer rotor.

In one possible embodiment, an aircraft electric motor cooling system is provided having an airflow path through a spinner which includes a first airflow path between an inner rotor and a stator, a second airflow path between an outer rotor the stator and a third airflow path along an outer surface of the outer rotor.

A stator for a rotating electrical machine is disclosed, the stator comprising a stack of stator laminations (20) forming a stator core (48; 60; 74; 80; 82). A lamination (20) comprises a plurality of cooling fins (28) arranged in at least one group of at least two fins. The cooling fins in a group are connected by a peripheral connecting member (30). The laminations are arranged in packs of at least one lamination. A group of fins (28) in one pack of laminations lies circumferentially between two adjacent groups of fins in an adjacent pack of laminations. A cooling fin (28) in one pack of laminations is interposed between two cooling fins in a group of cooling fins in another non-adjacent pack of laminations. This can allow a good thermal performance to be achieved while at the same time providing good mechanical strength and being cost effective to manufacture.

The present disclosure relates to electrical machines and methods for cooling active elements of electrical machines. More in particular, the present disclosure relates to rotors of electrical machines. An electrical machine may for example be a generator for a direct drive wind turbine. An electrical machine comprises a rotor comprising a plurality of active rotor elements, a stator comprising a plurality of active stator elements, and an air gap separating the active rotor elements and the active stator elements. The rotor further comprises one or more rotor openings configured for letting air flow enter the electrical machine and cool the active rotor elements and/or active stator elements in response to a rotation of the rotor.