Could somebody, please, explain to me what is CVT? Seeing how my knowledge of the technical aspect of F1 is only in its infant stage, if you don't mind, could you explain it in layman's terms (i.e. less technical)?
I have, most of the time, heard it called a "Constant Velocity Transmission" although i believe calling it a "Constant Variable Transmission" (like the above links) is the same thing.
Basically means simply that it can shift gears without ever interrupting the power from the engine to the wheels. So the car is under a Constant Velocity Acceleration. The FIA has outlawed these in F1.
General Motors develped the Dynoflow in the late 40's that was a hydrostatic system. Basically it was one gear that just slipped all the time. The faster the car went the more the tranny clamped down on the slipping gear. Never worked that well and GM stopped their R&D in the field. Other companies are now still working on it, but they will actually change gear ratios or change gears with no interruption in power to the wheels.
Additionaly, a perfect CVT will allow the powerplant to run at it's optimum revolutions. For either economy or sheer performance, this is a very desirable condition, since the powerplant does not have to be optimized for changing loads or revolutions.
This aspect of CVT fascinates me - I have only given it passing thought, but wondered what an F1 car would sound like with CVT (odd I should imagine).
What type of power curve would you produce for a CVT engine? Flatter? Steeper? I could probably guess this one, but would rather be told what and why by someone who knows
I'm already letting my mind wander - is this potentially going to put less strain on the engine as it changes speed less? How do they deal with engine braking? Does it consume more power in the drive train than cogs?
it would sound like it is running a static RPM all the time. I would guess an F1 cars optimal RPM is around 17,000.
The power curve would be extremely (if not perfectly) flat (but high). It would be making ~950 bhp all the time. To torque or Horse Power curve, just a line.
At present, straight cut gears with a clutch are the least power robbing components available for the drive train. Torque converters, automatic transmissions and the like rob more power from the engine than the above mentioned components. So for sheer performance and racing applications, straight cut gears and a clutch are the way to go. (at present) It must be assumed that a CV system would have more drag, steal more power from the engine. And usually, with more drag, there is more heat generated within the transmission.
But with a theoretically practical racing CV system, braking effort through the engine could easily be programmed in, giving a very good engine braking system.
As mentioned in the previous post, the engine would probably run at a constant RPM, and that's the beauty of it, allowing an engine designed for just one operating condition. But there may be problems, if the torque delivered is more than the tires can grip under adverse conditions. And that could lead to some form of traction control with fuel or RPM cutoff to allow the tires to grip, and not spin wastefully.
Thanks Dave a comprehensive answer - (I sort of expected that!).
Surely the traction problem would not be much different to now - Ok, the engine is always in the fat part of it's torque curve - but it's probably pretty close most of the time these days - the ultimate torque controller remains at the throttle pedal just as now, so a driver could control wheelspin by modulating his right foot. This leads me to think that you would have to get the engine braking side of the transmission spot on - how would it deal with someone riding out a drift using the throttle working between more/less throttle and needing instant changes to the engine braking/acceleration to play with weight transfer?
EDIT: I just re-read that you said "under adverse conditions" - I wonder if the thing could be "demand driven", so on smaller throttle openings the gears tend to stay slightly higher to soften the delivery (assume I understand you correctly in thinking you mean situations where you might use a higher gear than normal to get less torque to the track?)
But then, the engine RPM would be changing. It would no longer feed a constant horsepower and torque to the transmission, but one changing on load and/or driver input. If so, then what's the advantage of using a VT transmission?
Present transmissions shift at lightning speed, and assuming that straight cut gears and a clutch are the components that still have the least drag (compared to CV), then suddenly a CV looks a lot more complicated in it's application, and acceptance.
Of course, a CV transmission could select an almost infinite ratio between the engine and output shafts, and that may have tremendous advantages in long acceleration parts of the track.
So maybe a CV for racing applications is approximately equal in cornering, but superior in sustained acceleration. And it should be noted that a CV would probably add more parts, and mass, as compared to present transmissions.
There needs to be a distinction made between CVT and present F1 transmissions. A continuously variable transmission is continually delivering torque to the wheels, with an almost infinite final drive ratio.
In present f1 transmissions, it's pretty much conventional practice, with the exception of sensors and the hydraulics/electronics making things happen. The major goal of the modern F1 transmission is to reduce the idle time between shifts. Back when they were shfted with clutch and manually, the time the car was coasting between gears could be measured in whole tenths' of a second. So we now arrive in this day, where with the aids of paddle shifters and electronics and hydraulics making it happen, the time gap between one gear and the next is measured in thousands' of a second. So it's not a continuous delivery of torque from the engine to wheels, there are interruptions.
