Patent ID: 7479722

Claim:
A relative drive device for driving a first driving force transmission member and a second driving force transmission member relative to each other, the relative drive device comprising: first and second coil groups connected to the first driving force transmission member; and a magnet group connected to the second driving force transmission member, wherein the first and second coil groups each includes a plurality of electrically interconnected coils disposed along a predetermined direction at a predetermined pitch, the magnet group includes a plurality of magnets disposed with alternating north and south poles facing the first and second coil groups, and the first and second coil groups are disposed at positions that are out of phase with each other by an odd multiple of π/2 in electrical angles, the first driving force transmission member is connected to a prime mover by a drive shaft, the second driving force transmission member is connected to a load by a load shaft, the relative drive device is operable in any one of a plurality of operation modes including; (i) a relative acceleration mode in which the relative drive device transmits to the load via the load shaft a total of a first kinetic energy supplied from the prime mover through the drive shaft and a second kinetic energy that is converted from electric energy by the relative drive device; and (ii) a relative deceleration mode in which the relative drive device converts a part of the first kinetic energy to electric energy, and transmits to the load via the load shaft a residual of the first kinetic energy.