Power transmission device for hybrid cars

A power transmission device for use in a hybrid car for transmitting and cutting off driving force from an internal combustion engine or a motor to or from a drive train, said power transmission device comprising:

• a two-way clutch including
• (i) an outer ring;
• (ii) an inner member mounted within said outer ring, with said outer ring and said inner member having surfaces that are opposed to one another, wherein one of the opposed surfaces defines a cylindrical surface and the other of the opposed surfaces includes cam surfaces that face said cylindrical surface such that respective wedge-shaped spaces are formed between said cylindrical surface and said cam surfaces;
• (iii) a retainer mounted between the opposed surfaces of said outer ring and said inner member, said retainer including pockets positioned between said cylindrical surface and said cam surfaces;
• (iv) rollers received within said pockets, respectively, such that as said outer ring rotates relative to said inner member said rollers become engaged with said cylindrical surface and a respective one of said cam surfaces;
• and
• (v) an elastic member, mounted to said retainer and said outer ring or to said retainer and said inner member, for exerting a force against said rollers to urge said rollers in one relative rotational direction of said outer ring and said inner member toward a neutral position in which said rollers are disengaged from said cylindrical surface and a respective one of said cam surfaces;
• and
• a control unit for controlling said two-way clutch such that the driving force from the internal combustion engine or the motor is either transmitted to the drive train or cut off from the drive train by biasing said rollers, against the force exerted by the elastic member, into said wedge-shaped spaces, respectively, and into engagement with said cylindrical surface and a respective one of said cam surfaces.