Nissan and transmission supplier Jatco are developing a new Continously Variable Transmission which promises greater efficiency by providing a wider gear ratio than previous CVTs and lower internal friction. One short portion of the article (see link) states:
"Jatco also is developing a CVT for EVs that will be more efficient than the simple reduction gears used in today's EVs, such as the Nissan Leaf.
Carmakers tend to choose reduction gears because they are a cheaper option for otherwise expensive battery-powered vehicles, Usuba said.
But CVTs would help preserve battery life because they are more efficient in recharging the battery through brake regeneration, Usuba said. A CVT allows the electric motor to operate in a wider zone of maximum efficiency, further saving power."
The Volt does this now by using the motor/generator to spin the ring gear forward to allow the traction motor to operate in a band of RPMs where it operates most efficiently. It sounds as if this CVT is intended to achieve the same result, but is the increased efficiency worth the additional cost and weight of a CVT? As for higher levels of regen, couldn't this be achieved without a CVT simply by allowing the traction to generate more regen?
"Jatco also is developing a CVT for EVs that will be more efficient than the simple reduction gears used in today's EVs, such as the Nissan Leaf.
Carmakers tend to choose reduction gears because they are a cheaper option for otherwise expensive battery-powered vehicles, Usuba said.
But CVTs would help preserve battery life because they are more efficient in recharging the battery through brake regeneration, Usuba said. A CVT allows the electric motor to operate in a wider zone of maximum efficiency, further saving power."
The Volt does this now by using the motor/generator to spin the ring gear forward to allow the traction motor to operate in a band of RPMs where it operates most efficiently. It sounds as if this CVT is intended to achieve the same result, but is the increased efficiency worth the additional cost and weight of a CVT? As for higher levels of regen, couldn't this be achieved without a CVT simply by allowing the traction to generate more regen?
