Bosch is introducing specially designed continuously variable push belt transmission to enable electric powertrains to achieve a variety of applications. This will help electric cars achieve:
– Faster acceleration, higher top speeds and more wheel torque for towing and off-road performance
– Lower energy consumption
– Stepless shifting
Globally, the adoption of electric vehicles is on the rise, ranging from smaller city vehicles to larger sedans and SUVs. Nevertheless, e-mobility still faces a number of challenges: whether it concerns vehicles driving on steep roads, sports cars that must be able to reach high top speeds or vehicles that must tow a trailer or caravan.
Bosch is introducing the CVT4EV – compact variable ratio transmission to support the performance demands of electric vehicles for a wider audience. Bosch says that the system will improve the economy and performance of the electric powertrain, while maintaining the smooth and comfortable character of the electric motor.
Let’s have a look at how CVT will help the EVs achieve higher efficiency and OEMs realise cost benefits.
Higher efficiency and lower energy consumption
The variable gear ratio of the CVT4EV ensures an optimal trade-off between efficiency and performance. The system controls the speed and torque of the electric motor and improves the vehicle’s performance. This results in faster acceleration, higher top speeds and more torque at the wheels for towing and off-road performance. Continuous shifting allows maximum power to be applied continuously, allowing the vehicle to accelerate better and drive faster up the mountain. Power also remains more available across the vehicle speed, leading to higher top speeds and lower energy consumption.
By running the electric motor at its most efficient operating point, the CVT4EV ensures lower energy consumption. In the combined efficiency of the inverter, electric motor and CVT, the system finds the optimum operating point of the electric powertrain by controlling the transmission ratio of the CVT. That is the point where the power and torque are delivered in the most efficient way. Due to the reduced torque and speed requirement of the electric motor, the CVT4EV makes a more compact electric motor possible. Alternatively, a larger driving range with the same engine can be selected.
Cost benefits for OEMs
CVT4EV makes a single drivetrain suitable for a wide variety of applications – mid-size car, sports car or light commercial vehicle. This solution consists of one platform with a CVT4EV module, an inverter, an electric motor and a final drive with a ratio adapted to the vehicle.
This creates a cost advantage for car manufacturers, with less cost and complexity in the development, production and aftermarket of their applications and vehicles. This variability also offers an improved user experience through the availability of different driving modes.
Unlike alternative multi-stage solutions for electric vehicles, the CVT4EV introduces fewer restrictions on torque and revs. In addition, it offers completely smooth shifting without shifting shocks – a feature that is a must for EVs. Extra measures to mask switching shocks are therefore not necessary. The potentially larger control range of the CVT reduces the revs of the electric motor, resulting in a smoother and quieter ride.
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