iirc Mudflap's view is that the quill shaft enables shifting without use of throttle, ignition cut or fuelling cut ....
but yesterday I heard Mr Coulthard say that Alonso had a problem as he had lost his throttle blip
Scootin is of course correct. The preload on these clutches is adjusted so that the clutch slips at excessive inertial torques, protecting the driveline during harsh shifts. Interestingly, I am pretty sure I have heard F1 have experimented with motorcycle style ramp slipper clutches although I am not sure if the purpose was to avoid rear wheel slip or protect the driveline (or both?).
Is this why you hear some oscillation when changing gears?
This was more noticeable with V8 engines that upon upshifting you'd hear some oscillation.
Very noticeable in this video: https://youtu.be/aolTbZkysW8?t=24
I read somewhere that the oscillation is due to the purposely torsionally flexible driveshafts. They would help buffer any torque spikes, and I guess compared to slipper clutches, require no extra parts and absorb nearly zero energy.
compliance between the gears and the load comes mainly downstream of the crownwheel
ie from the tyres, the driveshaft joints and ok the driveshafts (joints and shafts presumably designed for high compliance)
the compliance 'seen' by the gears is factored by the crownwheel:pinion ratio
this is about 60% of that used in the NA days as the engine revs are about 60% of the NA's
Last edited by Tommy Cookers on 04 Jun 2018, 14:58, edited 1 time in total.
In high speed high performance engines it is often impossible to shift torsional resonances out and away from the operating RPM range so compliant drives are empoyed primarily to isolate vibration.
The principle is exactly the same to that of a rubber AV mount, except that hysteresis damping across a steel shaft is very low and external damping (e.g. friction dampers) is often required.
In short compliant drives are used to reduce transmissibility by lowering the natural frequency of the system compared to the frequency of the excitation.
The crankshaft quill serves a few more purposes though. It allows the clutch to be relocated in the gearbox in order to raise the natural frequency of the crankshaft so that even if the entire driveline resonates, the vibratory torques across the crank are small as the quill becomes the node (point of 0 angular displacement).
The load on the quill is easier to manage as it is loaded in pure torsion as opposed to the crank which is loaded in combined torsion and bending.
Secondly the ability of a system to cope with sudden loads producing high strain rates (gear shifts) is dependent on its ability to absorb energy - again the compliant drives help here by converting the "impact" energy to strain energy.
Engines typically have torsional spring packs in the clutch that are technically vibration absorbers (~ capacitor for torsional vibration), but are often called vibration dampers even though they technically do not dissipate energy like a damper. Well-intentioned people who try to get their workplaces to refer to these devices as absorbers rather than dampers often start inadvertent wars and many people die.
The limiting factor of how effective VA are is usually the package space available for them within the ID of the clutch friction material. F1 clutches are obviously tiny, and I never knew how the VA function was handled until Mudflap's comment about torsion-only quills. Neat. In practice you could put the torsionally-compliant quill either upstream or downstream of the clutch?
The whole driveline, from the upstream tip of the MGU-K to the compliance of the pavement under the contact patches, is a large and complex torsional vibration system. The halfshafts between final-drive and wheels are probably designed to have specific frequencies, but making these "soft" doesn't eliminate the significance of higher resonances upstream of there.
Secondly the ability of a system to cope with sudden loads producing high strain rates (gear shifts) is dependent on its ability to absorb energy - again the compliant drives help here by converting the "impact" energy to strain energy.
