Clutchless Shifting of an Automated Manual Transmission in a Hybrid Powertrain



Commercial Vehicle Engineering Congress
Authors Abstract
The normal approach to shifting a manual transmission in a vehicle includes a clutch which connects the engine to the transmission. When shifting, the relative speed of the engine and wheels changes. The transmission is disconnected from the engine with the clutch and the gears in the transmission are pressed together until they engage. There are small friction synchronizers inside the transmission, but these are only designed for the inertia of the gears and the clutch pressure plate. The clutch is required to synchronize the transmission speed with the engine speed after a shift, and to remove the load from the transmission before a shift. Described is a method for automating a manual transmission hybrid-electric powertrain which doesn't require a clutch. A hybrid drivetrain including an electric motor and a combustion engine has the benefit of much better speed and torque control than a combustion engine alone. Drivetrain speed can be controlled to take the load off the transmission, allowing it to be shifted into neutral. Once the transmission is in neutral, the electric motor can synchronize the engine side to the correct speed quickly and accurately, allowing the transmission to shift into the next gear. This provides rapid, efficient shifting without a clutch.
Meta TagsDetails
Breen, J., and Bower, G., "Clutchless Shifting of an Automated Manual Transmission in a Hybrid Powertrain," SAE Technical Paper 2011-01-2194, 2011,
Additional Details
Sep 13, 2011
Product Code
Content Type
Technical Paper