What engine vibration orders can be attenuated by the Clutch?

[JagB]

I would like to understand the single plate clutch a little more,

What engine vibration orders can be nullified/reduced by the clutch transferring from engine to transmission/gearbox?

Is the clutch designed to take only the main order of the engine? or up-to 2nd harmonic?

what is the optimal vibration frequency range I should select to analyze for a clutch? on what basis.

Thank you for your inputs in advance.

JagB

 

[BrianPetersen]

You're talking about the mechanism inside the clutch disk in which the torque is transmitted through from the friction surface to the transmission input shaft via springs, right?

I'm not aware of those being designed to do anything other than soak up the series of hammer-blows (power strokes) and uneven crank rotation (due to all pistons of a 4-cylinder engine simultaneously being stopped at TDC/BDC or near max piston velocity halfway between, the inertia of which goes back and forth between crank and pistons) so that this doesn't all get transmitted through the gears.

 

[GregLocock]

In a manual the clutch springs are mainly tuned to attenuate idle rattle in the gearbox, in neutral.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[JagB]

Hi Greg,

There are pre-damper (idle rattle and creep rattle sometimes) and main stage damper for drive rattle attenuation.

I would like to understand that whether clutch can eliminate or reduce engine orders (1, 2, 3, 4 etc,. till how many?) on what basis?

 

[GregLocock]

At what rpm? Dual mass flywheel helps at idle other than that I'd say no.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[BrianPetersen]

Just to be clear - The mechanism inside the clutch is only going to be capable of evening out uneven rotation-speed of the crankshaft so that less of this is transmitted to the gearbox (whether the uneven rotation-speed is due to first-order or second-order inertial effects or due to compression and firing impulse events). It isn't going to do anything about vertical-shake or rocking-couple vibrations of the engine block as a whole due to primary or secondary imbalance.

A normal (conventional) single-plate flywheel has this vibration damper inside the clutch disk which is coupled to the transmission input shaft. If the driver has their foot on the clutch pedal then this is uncoupled from the engine and has no effect. If it is a dual-mass-flywheel design then this vibration damper is on the flywheel side of the clutch disk and is in effect even when the driver has their foot on the clutch pedal.

VW diesels went to the dual-mass design in the late nineties to supposedly reduce noise at idle.

Those springs are obviously going to have a limit to the amount of torque that can be transmitted before they bottom-out and cease to perform their crank-speed-pulsation-absorbing effect. I don't know how that limit compares to rated engine torque output.

 

[BrianPetersen]

Found this

https://trade.mechanic.com.au/news/...g-while-protecting-the-drivetrain-from-damage

 

[GregLocock]

The torque required to lock out the clutch springs is tiny, from memory.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[BrianPetersen]

That's surely application specific. The ones I've seen use what look like die springs, and any deflection by hand is barely perceptible. I've never put a torque wrench to one to see what it took to bottom out the springs.

There's no significant damping, though. Just springs, in those that I've seen.

My VW TDI had a seized DMF when I sold it (430 000 km). Common fault on those. Made for very tricky driving in traffic. The clutch tended to be either on or off, next to no modulation.