cvt in electric car for racing purposes?

[Huskte]

This is just a completely random thought i just had, keep in mind i’m rather sleep deprived at this point in time so forgive me if this is rather stupid.

BUT does this make any sense, the idea is that you use a combination of the throttle position and gear ratio to maximise torque for accel and deccel

under acceleration the speed / acceleration would be controlled by the the gear ratio of the cvt. As you could have throttle 100% pinned basically at max rpm and use the cvt to change ratio as you’re accelerating to provide the maximum possible torque for your given speed

Then under braking the cvt could act inversely, so as to provide as much regen braking force as possible and recover as much energy as possible

[jrbe]

Yeah it makes sense. But a few big things going against it. Most electric drivetrains are looking for maximum efficiency. Extra bearings, a cvt, etc. all mean extra drag so most oems don't incorporate them with the exception of the Toyota hybrid planetary cvt systems. There has been talk of using one of these with 3 motors or modifying one motor to use the planetary cvt. The Lexus 450h / 600h transmissions have a planetary and are 2 speed.
A cvt using a chain / belt will likely have a maximum speed below the electric motor's.
If you use 2 electric motors you'll be using 1 motor to slow down the planetary at times to change the ratio. It's input/ regen would be just changing gear ratio.
Lots of mechanical, actuation, cvt mapping, & coding, challenges along with RPM limits of bearings, chains, motors, etc.jto constantly deal with.
Not impossible, just a lot of things in different disciplines to get right.

[arber333]

This is just a completely random thought i just had, keep in mind i’m rather sleep deprived at this point in time so forgive me if this is rather stupid.

BUT does this make any sense, the idea is that you use a combination of the throttle position and gear ratio to maximise torque for accel and deccel

under acceleration the speed / acceleration would be controlled by the the gear ratio of the cvt. As you could have throttle 100% pinned basically at max rpm and use the cvt to change ratio as you’re accelerating to provide the maximum possible torque for your given speed

Then under braking the cvt could act inversely, so as to provide as much regen braking force as possible and recover as much energy as possible

Wouldnt you achieve the same result by using manual transmission with say Leaf motor installed directly (no clutch) and robotize actuation?
Find transmission data for best synchro speeds in each gear
Use combination of 2 or 3 servo motors to actuate the two manual levers on tramsnission itself. This was done on Citroen cars i think.
EDIT: Could simply use one servo if you make correct lever ratios and reverse direction in inverter.
Build VCU to monitor input RPM vs output RPM and decide on shifting and implement throttle control while shifting

Pros...
1. No clutch, shifting by RPM limits
2. keeping motor within best torque ratio
3. constant pull with 0,5s shift intervals
4. Really high final speed possible

Cons...
1. Software development
2. possibly surge shifting without clutch (need to disable regen while shifting)
3. Bearing and gear drag
4. not sure of better acceleration 0 to 60???

[Huskte]

yeah it’s probably not worth all the extra issues it causes, but would be interesting to see if it pops up somewhere someday from an oem