I’ve always wondered about electric cars in general and the question how does an electric car transmission work?
Electric cars don’t have transmissions as an electric motors delivers power and torque very differently than a combustion engine. And frankly, they don’t need so much of a crutch, which is really all a transmission is.
An electric motor has so much torque almost from one RPM that it doesn’t need to rev up to get a lot of torque, which is what really moves the car. As a result, it doesn’t need a low first gear to get going.
In a traditional car, the combustion engine only operates in a narrow range of speeds, measured in RPMs or revolutions per minute. Typically, if you get below 500 RPMs the motor will stall, and if you get over 7,000 RPMs the motor will overheat and both of those things are never good.
So to keep the car comfortably within that range, multiple gears are needed to change how fast the wheels turn, even as the engine speed stays roughly constant.
This works because gears that have more teeth will take longer to spin completely, meaning that they’ll move slower. so your typical car’s first gear has three-point eight two times more teeth than the gear on the engine.
Meaning that it will go three-point eight two times slower than the engine, by the time we get to six gear it actually points eight two times smaller, meaning that it will go twenty percent faster than the engine itself.
To be able to travel in a wide range of speeds normal cars need gears to keep the engine happy, but, in an electric car, they have electric motors that can go anywhere from zero to over eighteen thousand RPM. So to go faster all you have to do is just increase the motor speed.
Another big reason cars need a gearbox is torque. Torque is basically a rotational force. In the case of lug nuts on a tire you have to apply a lot of torque to get them moving, cars also need a lot of torque at first to get started.
Power equals torque times speed, so speed decreases and torque increases and vice versa.
So since first gear is 3.8 times slower than the motor, that means that it has three-point eight times more torque than if that engine was hooked up directly to the drive shaft.
All this torque is necessary to get your car moving from a standstill, but since the power from the motor has to stay roughly constant, with a high torque you’re gonna be revving up your car a lot to really gain any speed.
So to prevent running your motor too high you would shift into a higher gear to go faster, and at that faster speed, you won’t need as much torque because the wheels already have quite a bit of momentum.
The cool thing about electric motors is that they have their maximum torque at zero RPM and that max torque stays until about 4000 RPMs. At that point, the car started going around 30 miles per hour, and it doesn’t need all of that torque.
Electrick cars do have one gear, but it’s just one that is nineteen point seven to one which the engineers say gives the perfect balance between torque and speed. I’d say I have to agree with them
The reason why I love EV’s so much is that at their core, they’re so simplistic. You know, it’s just these copper wires and magnets and when you give her electricity it goes, and it goes really fast.
Could Electric Cars Have A Manual Transmission in the future?
So we have two questions that we really need to answer in order to discuss whether or not electric cars in the future could be using manual transmissions. First of all, is it possible? And second of all, is it logical?
The first question is it possible? Is a very simple yes, it’s super easy to do if for example you just took a traditional manual transmission internal combustion engine vehicle and swap that internal combustion for an electric motor everything could work
So you’d have your electric motor, that would go to a clutch, that clutch would then rotate a layshaft, the layshaft allows you to choose between two different gears.
So, for example, a two-speed transmission which you’re using your manual gearshift to choose between one and two transfers all that power which is then sent to the rear differential or the driven wheels. So ultimately yes, it’s it’s very simple to implement.
A clutch could assist you in a scenario like this for gear shifts, basically, all you’re doing is swapping out the internal combustion engine for an electric motor. Of course, you have to have the controllers in the battery but it could be done.
The other question, is it logical? And this is probably the one that dictates whether or not it will actually happen.
First of all-electric motors don’t stall like internal combustion engines, so when the vehicle is stopped in an internal combustion engine you need that clutch.
Because you have a speed differential between your engine which is idling, let’s say 800 RPM, 900 RPM versus the transmission where that isn’t rotating because it’s connected to your wheels.
With an electric motor, because you don’t stall you can start from zero RPM, you don’t need to use that clutch to start from a standstill. You can just press on the accelerator pedal and away you go. So you wouldn’t need it for the start and ultimately, the clutch portion of this isn’t really necessary.
So electric motors have a lot less Inertia to them.
There’s also less weight in there, you don’t have for example the crankshaft with the counterbalance of the different piston motions, you don’t have to worry about a flywheel.
You don’t have to have balance shafts and engines that require balance shafts for vibration issues, so you can remove a lot of weight from an electric motor.
You have a smooth torque delivery, so you don’t need that flywheel and so ultimately, because it’s low inertia it means it can change its speed very quickly and this allows for very easy shifting.
If you had an electronic mechanism to shift Gears which knew which gear you’re going to next you could have very quick upshifts and downshifts.
For upshifts, you could use regen to lower that motor speed very quickly, and you could apply some acceleration for rev-matching downshifts and do that very quickly.
So it will be capable of extremely quick shifts because the electric motors are low inertia and can change speed very quickly.
And finally which was discussed is you don’t actually need gears for a lot of electric vehicles you can get away without them.
They just add complexity, they add weight, they add an efficiency loss, when you could just have this directly or just a simple gear reduction before driving a wheel.
There’s a lot of benefits of just matching an electric motor with a wheel and having one at each corner rather than sending it through this complicated drive train where you’re going to have efficiency losses.
For street cars where you’re only maybe accelerating up to 100 mph tops for everyday cars, one gear is perfectly acceptable, in fact, Renault is also moved away from using the two-speed manual shifting setup in favor of a single gear for reduced weight and reduced frictional losses.
While the more aggressive two-speed setup can allow for quicker starts or acceleration out of low-speed corners, it seems the trade-off for the multi-gear setup wasn’t worth it.
Renault’s design strategies continue to pay off as they’ve won all three season team championships in Formula E.
Now does this mean that they couldn’t exist in the future for streetcars? Perhaps they could, and there’s no reason really why they couldn’t. If you really do think about it, even today looking at manual transmissions, are they logical?
They’re really not for driving joy rather than a logical reason because there are quicker transmissions out there there are more efficient transmissions out there.
We use these simply because they’re enjoyable to drive. So it would be cool to see if perhaps in the future we do get something with an electric power train, but that’s also using a traditional manual transmission.
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