The present invention relates to a driving apparatus for a hybrid vehicle.
There exists several kinds of driving apparatuses for hybrid vehicles in which a conventional automatic transmission is utilized, and in which a motor and a clutch are located at a torque converter portion. In such a driving apparatus, as described in Japanese Patent Application No. JP-A-2004-1708 for example, a clutch (starting clutch) is interposed between an engine output shaft and an input portion of an automatic transmission apparatus, and a rotor of a motor is integrally fixed to an engine output side (primary side) of the clutch. In other words, the primary side of the clutch has a shell (drum) structure as well as a torque converter, the clutch is accommodated in the shell structure, and the rotor of the motor is integrally fixed to a front cover portion, which configures the shell structure.
Accordingly, in a conventional torque converter, a front of the front cover is fitted to the engine output shaft as a center piece, a rear case is rotatable relative to an oil pump body, and the shell has an oil-tight configuration. This driving apparatus is thus configured as a doubly supported structure to some extent.
However, in the apparatus, in which the rotor of the motor is connected to the primary side of the clutch, the engine output shaft and the motor rotor are connected. Accordingly, at the time of starting by the motor, the engine needs to rotate idly. Therefore, a loss of power occurs. Further, when the motor is utilized as a generator for regeneration, regeneration is difficult until the vehicle stops because of interference by an engine rotational frequency. Further, though the shell structure portion (front cover), to which the rotor of the motor is fixed, becomes the doubly supported configuration to some extent, the front thereof is supported at the engine output shaft by the centerpiece. It is thus difficult to support a shaft center of the front cover with high precision because of influences from vibrations of the engine, or the like. Accordingly, an air gap between the rotor fixed to the front cover and a stator fixed to a housing becomes large, and it is therefore impossible to sufficiently exert performance of the motor.
In the light of the foregoing, for example, as described in U.S. Pat. No. 6,585,066, an apparatus is suggested in which a rotor of a motor is connected to a secondary side (automatic transmission apparatus side) of the clutch. In this apparatus, a hub side of the clutch is a primary side connected to an engine output shaft, and a secondary side includes a flange member having a flange. A front of the flange member is opened, and is penetrated with a connecting member (a damper spring, a flexible plate, or the like) that connects the clutch primary side including the hub with the engine output shaft.
In this apparatus, when a vehicle starts, a torque of the motor can be transmitted directly to an automatic transmission apparatus without being interfered by the engine by turning off the clutch. When the motor is utilized as a generator for regeneration, kinetic energy can be regenerated as electric energy until the vehicle stops.