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Bosch demonstrates CVT for EVs

Certain applications can pose challenges for an 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%. Depending on design, this can provide more torque in traction mode, better acceleration, or a higher maximum speed.


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 speeds, a smaller gear ratio improves acceleration and handling characteristics on ascents, while a higher ratio enhances efficiency at higher speeds, as well as increasing 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.


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, Bosch says. 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.



This is exactly what I've been stating for nigh unto 5 years. Hopefully, some geniuses will start to wake up.


push belt
use eCVT


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William Stockwell

Do I believe a CVT transmission could improve efficiency and some other aspects of an EV, Yes but it also increases cost, weight, and introduces another point of failure in the drivetrain -many things sound great if you just talk about the pros and forget the cons.


Personally, I think that this is a bad idea. Under some conditions, you get a few percent of efficiency but you have a heavier and more complicated drive train with a device that is continuously slipping and therefore continuously wearing. If there really is a need for such a device, I would go with 2 motors and a planetary gear train.


Exro technologies has a solution

Bob Niland

Sigh. Not needing a multiple-ratio transmission was one of the attractive promises of electric cars. I've always considered CVT to be a disqualifier on an IC car, for the reasons already enumerated in other comments (plus noise).

Ing. A.S.Stefanes

@ SJC, do you even know what eCVT is? if you are referring to Toyota's HSD, which is classified as the eCVT, its and ICE motor driving a generator driving an e-motor. How is that applicable in the case of an EV?

The rest, if you dont understand why EV's can greatly benefit from at least more than 1 gear then dont even bother commenting why this is such a bad idea.
Everything has pro's and con's. Even a single speed has con's.
As if a CFT would actually weigh much more than just a single speed gearbox. And if it did, the smaller motor could make up for it again.
A simple 2 speed planetary gearbox can already improve overall efficiency quite a lot. The higher top speed is nonsensical. But being able to use a smaller motor yet still getting high torque at low speeds and get the motor in the right rpm and efficiency at higher cruising speeds absolutely outweighs the con's.


@ Ing. A.S.Stefanes
I can endorse wholeheartedly what you have stated.


The most vulnerable part of an EV is the battery. Its total life is always too short and any means to prolong its life is always welcome.
High surge currents resulting from high torque demand (e. g. accelerating whilst towing) certainly make no contribution to enhance life expectancy. A transmission achieves exactly that. It is absolutely necessary to convert a small torque to high one without excessive harmful drain on the battery. I'm convinced that the best way to cope with such problems is by means of a tranny and what could be better suited for that purpose then a E-CVT with a metal band? Anyone?


Easy for you to criticize


@ Ing. A.S.Stefanes, do you even know what eCVT is? A planetary transmission can have a fixed ratio, 2 ratios as used in most automatic transmission for ICEs, or be infinitely variable by using 2 electric motors driven at different speeds. You can even make the output go to zero and then reverse but that is not needed with electric motors.

I do think that you need a shifting transmission (CVT or otherwise) for a Light Duty Electric Vehicle. The new Ford Lightning has two motors but they are separate front and rear drives. Maybe the heavy duty pickups when they come out will have a transfer case with a low ratio for hauling heavy loads off-highway.

And I again will state that I think that these belt type CVTs are a cheap but bad solution for any vehicle other that maybe off-road 4 wheelers or snowmobiles as they continuously slip and wear. I know that GM looked at CVTs in the early 80's when I worked for the company that built all of their transmission lines. You could get the engines to run more efficiently but these transmissions are less efficient. Anyway, GM ended up going with more speeds in their lockup planetary gear automatic transmissions and Ford opted for dual clutch transmissions. Both of these are better solutions in my opinion.


I meant to say:

I do NOT think that you need a shifting transmission (CVT or otherwise) for a Light Duty Electric Vehicle.

Account Deleted

Not a fan of CVT on any type of auto. However, multispeed transmissions do have benefits for EV. Please read this Car and Driver article which states:
"Having a multispeed transmission in an EV provides the same benefits that it does in a gasoline-powered car: improved low-speed acceleration and increased efficiency at high velocity by lowering the rotating speed of the power source. In other words, the ratio spread of the two-speed transmission will help the Taycan's highway driving range while also making it quicker."
A two speed automatic is all that is necessary like in the Porsche Taycan.

Account Deleted

EV are evolving all the time. Hewland which has been building racing transmissions for decades is now working with Formula E and their rules allow multispeed transmissions. However, most teams stay with 1 or 2 speeds, no more than 3
@Vmacd69 - Thanks, checked out Exro Technologies.
Exro's Dynamic Power Management (DPM) is a software system, which controls electric motor coils (in the stator) to enable two separate torque profiles within a given motor. The first is calibrated for low speed and high torque, while the second provides expanded operation at high speed
(https://insideevs.com/news/430331/exro-ev-motors-electromagnetic-gearbox/ and expo.com).
Also, Exro Technologies has a development partnership with Zero Motorcycles, which sounds interesting.


Exro Technologies looks interesting


I suspect that the reason that the Porsche Taycan has a 2-speed transmission is to increase the top speed. My Chevy Bolt has enough torque starting off to break loose the front tires but is limited to 92 mph which is more than enough for normal driving but maybe not enough for a Porsche owner.

It should be relatively easy to make a 2-speed transmission as the motor can be programmed to synchronize the speed to make the shift without a clutch.

Anyway, still no good reason to use a traction type CVT.


@ sd: " My Chevy Bolt has enough torque starting off to break loose the front tires....." I believe you but that is not the point. That torque is developed at the expense of the battery. A transmission would eliminate that torture and extend its life expectancy.

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