Belleville washer spring model

[dolcini]

Hi,

I'm doing research work for Renault on clutches and I need the force equation of the Belleville spring for monodisk dry clutches; something like Fplate= f(X1, Xplate) where X1 is the position of the "fingers" of the spring (i.e. where the actuator pushes)

Thanks!!
Pietro

 

[israelkk]

If you design a belleville spring for a clutch you need a spring with a "constant" force over a range of the deflection of the spring so that the force will not reduce when the clutch wears out.

 

[NickE]

What kind of forces do you need. There may be several options. The spring equations are quite complex for a Belleville (and any similar Disc spring).

Nick
I love materials science!

 

[arnoldh]

for a clutch spring with fingers (i.e. a diaphragm spring) you will need an adjusted version of the "standard" belleville spring calculations by almen & lazlo. you will then get a quite good approximation (although I think every spring manufacturer uses in house adjusted equations to cope with the limitations of the A&L equations). You can find quite a lot of usefull information in SAE HS 1582. Regarding israelkk's post: this is quite new to me. clutch springs normally don't have a constant force over deflection. The force normally decreases when actuating.

regards,

Arnold

 

[Gearhead]

Spring Manufacturers Instittute offers the Advanced Spring Design Program which includes Bellevilles.
Thier site is

http://www.smihq.org

 

[DISCMAN]

Hi Dolcini,

I agree with arnoldh. You wan't get a constant force over the whole deflection with a belleville washer.
Did you have find a solution ?
If not I can support you with a calculation program.
For a clutch application they normally take a proportion with 1,4 for free height ho to thickness t.

 

[israelkk]

arnoldh

What I meant that a belleville spring with h/t=1.41 has a range of a "constant" force vs deflection (from both sides of its "Flat loaded position" . A clutch that uses a belleville spring that is loaded to the end of this range will display "constant" force as long as the spring deflection is within this range. So as long as the wear of the clutch disk is within this range the force will stay "constant". The size of this "constant range" depends on the belleville design.