Patent ID: 7752936

Claim:
An automatic transmission assembly for transmitting rotary power from a crankshaft to a drive train component, said automatic transmission assembly comprising: a main shaft operatively connected to said crankshaft; an auxiliary shaft operatively connected to said main shaft; a transmission unit having a plurality of gear pairs which provide a plurality of gear positions between said main shaft and said auxiliary shaft; a twin clutch assembly comprising a first clutch and a second clutch disposed on one of said main shaft and said auxiliary shaft, respectively, said twin clutch assembly configured to selectively and operatively transmit rotary drive power from the crankshaft to said transmission unit; a shift drum operatively connected to the transmission unit; a shift fork selectively engagable with the shift drum; a shift position sensor for detecting an angular position of said shift drum; said shift position sensor being operatively connected to said shift drum; a controller which is operable to select an operative angular position of the shift drum for actuating the shift fork; said controller controlling engagement and disengagement of said twin clutch assembly for selecting one of said plurality of gear pairs to transmit said rotary drive power from the crankshaft to said transmission unit; wherein said transmission unit shifts transmission of said rotary drive power between two adjacent gear positions of said plurality of gear positions in response to switching of said first clutch and said second clutch into and out of engagement position when said shift drum is in a predetermined angular position for one of said plurality of gear positions, wherein said controller performs a preliminary upshifting action in advance by angularly moving said shift drum to a first selected angular position based on a next gear position in an upshifting direction while said rotary drive power from the crankshaft to the transmission unit is being maintained at a present gear position, wherein when an upshifting command is output, said controller engages one of said first clutch and said second clutch with said crankshaft depending on the upshifting command, and when a downshifting command is output, said controller performs a preliminary downshifting action in advance for angularly moving said shift drum to a second selected angular position based on a next gear position in a downshifting direction based on said downshifting command, and when the shift position sensor detects a completion of said preliminary downshifting action based on said selected second angular position of said shift drum, said controller operatively engages one of said first clutch and said second clutch with said crankshaft.