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Press release #Electrified mobility
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From caravans to sports cars: Bosch extends the electrical car’s repertoire

cvt4ev

Continuously variable transmission (CVT) improves efficiency and performance

  • Smaller battery or greater range thanks to CVT
  • More torque when towing and driving off-road
  • Faster acceleration and higher maximum speeds
  • Continuously variable shifting for optimum comfort and convenience
Thorsten Schönfeld

Thorsten Schönfeld

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Stuttgart, Germany/Tilburg, Netherlands – The electromobility business is booming. Certain applications, however, still pose enormous challenges for the electrical powertrain: when towing trailers, tackling steep ascents with a heavy load on board, or driving longer freeway stretches at high speed, the battery charge drops rapidly. Almost all electric cars have only one forward gear, but in such situations a multi-stage transmission can work more efficiently. To demonstrate this, Bosch installed a continuously variable automatic transmission (CVT) with push belt in a test vehicle. Called CVT4EV, this transmission increases efficiency by up to 4 percent. Depending on design, this can provide more torque in traction mode, better acceleration, or a higher maximum speed.

The CVT4EV expands the electrical car’s repertoire,

says Gert-Jan van Spijk, who is in charge of CVT engineering at Bosch.

“The CVT4EV expands the electrical car’s repertoire,” says Gert-Jan van Spijk, who is in charge of CVT engineering at Bosch. And because the transmission adjusts the ratio continuously without loss of traction, the driving ease typical of e vehicles is not lost. Bosch contributes its systems expertise plus several components to the complete CVT solutions offered by specialized transmission manufacturers.

Better performance, lower energy consumption

The CVT4EV’s variable gear ratio provides the best possible balance of efficiency and performance. To this end, the system can freely control the speed and torque of the electric motor. At low vehicle speeds, the downshifting capability of the CVT improves acceleration performance and gradeability. At higher vehicle speeds the upshifting capability enhances efficiency and increases top speed. In addition, it provides increased torque when towing and driving off-road, yet with lower energy consumption. Especially at constant speeds, the CVT4EV reduces the vehicle’s energy requirements.

Due to the electric motor’s reduced torque and speed requirements, a cheaper and more compact motor can deliver the same or even better performance. Alternatively, the same motor can achieve a greater range. As a result, manufacturers of electric vehicles can find the optimum balance between battery capacity and range.

High versatility, low complexity, reduced costs

This powertrain solution consists of a CVT4EV module, an inverter, an electric motor, and an axle drive with a ratio adapted to the vehicle. It is suitable for a wide variety of applications, from mid-size cars to sports cars to light commercial vehicles. Since individual software programs can often adapt the powertrains to the respective area of application, fewer hardware variants are needed. This cuts costs in both development and production. The use of CVT4EV also enables different driving modes for different types of vehicles, so carmakers can stand out from the competition by offering their brand’s typical handling in all their vehicle segments. As a result, end users get the driving experience they associate with the respective marque.

Compared to alternative variable solutions for electric vehicles, the CVT4EV offers a greater increase in the torque and engine speed available to the wheels. It also ensures completely smooth shifting without jolts – a must for electric vehicles. In addition, the larger spread of the CVT reduces the speed of the electric motor, resulting in an even smoother and quieter ride.

The concept of the CVT4EV with numerous Bosch components comes from Bosch Transmission Technology B.V., a Dutch subsidiary of Bosch. Based in Tilburg, the company is a leader in the development and mass production of CVT push belts. Full CVT4EV solutions are available through specialized transmission suppliers.

Mobility is the largest Bosch Group business sector. In 2023, its sales came to 56.2 billion euros, or just under 60 percent of total Group sales. This makes the Bosch Group one of the leading mobility suppliers. Bosch Mobility pursues a vision of mobility that is safe, sustainable, and exciting. For its customers, the outcome is integrated mobility solutions. The business sector’s main areas of activity are electrification, software and services, semiconductors and sensors, vehicle computers, advanced driver assistance systems, systems for vehicle dynamics control, repair-shop concepts, as well as technology and services for the automotive aftermarket. Bosch is synonymous with important automotive innovations, such as electronic engine management, the ESP anti-skid system, and common-rail diesel technology.

The Bosch Group is a leading global supplier of technology and services. It employs roughly 429,000 associates worldwide (as of December 31, 2023). The company generated sales of 91.6 billion euros in 2023. Its operations are divided into four business sectors: Mobility, Industrial Technology, Consumer Goods, and Energy and Building Technology. With its business activities, the company aims to use technology to help shape universal trends such as automation, electrification, digitalization, connectivity, and an orientation to sustainability. In this context, Bosch’s broad diversification across regions and industries strengthens its innovativeness and robustness. Bosch uses its proven expertise in sensor technology, software, and services to offer customers cross-domain solutions from a single source. It also applies its expertise in connectivity and artificial intelligence in order to develop and manufacture user-friendly, sustainable products. With technology that is “Invented for life,” Bosch wants to help improve quality of life and conserve natural resources. The Bosch Group comprises Robert Bosch GmbH and its roughly 470 subsidiary and regional companies in over 60 countries. Including sales and service partners, Bosch’s global manufacturing, engineering, and sales network covers nearly every country in the world. Bosch’s innovative strength is key to the company’s further development. At 136 locations across the globe, Bosch employs some 90,000 associates in research and development, of which nearly 48,000 are software engineers.

Additional information is available online at www.bosch.com, www.iot.bosch.com, www.bosch-press.com.

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