Electronic Clutch Activation

[Chapo]

Hello,
I have been looking for some information on electronic clutch activation. I have gone through the previous forums and found information on electro-pnumatic actuaton, but I am interested in hearing from some teams who run full electronic clutch activation.
I am just wondering how you get the required activation times for the clutch (I am thinking around 0.3 seconds, correct me if I am wrong). I have been looking at using the powersteering (electric) rack/motor from some modern cars but I think this may be to heavy, I also have some other thoughts about activation but I feel they are to big and to heavy. Any thoughts on solutions to this problem would be greatly appreciated.

Matthew Chapman

[Mike Sadie]

Ya, that motor sounds pretty big. Try looking into linear actuators. Add a potentiometer to it and you can make a closed loop control system like R/C servos. As for clutch time, that depends on how long it takes you to engage the gear.

What kind of shifter setup are you using (pneumatic, manual, etc)?

[Kirby]

There are many different ways to have an electrical clutch actuation, I know, becuase I've researched many of them myself.

Utimately it was a friend of mine on the team that figured out the most appropriate actuation method (for our team atleast).

First decide what you want to use your clutch for..just for taking off or down-shifting aswell?

Once you have that information you know the speed at which your clutch will need to be engaged/disengaged.

Determine the force required to actuate the clutch lever on the engine, find out the engagement point of the clutch over the entire throw of the lever.

Find out how much current the cars electrical system can spare for the clutch in a race.

Now you have a force, distance, time and power supply.

Scour your resources for applicable products.

[exFSAE]

I'd have to imagine electronic actuators would require a good bit of juice to really modulate and hold that force.

Pneumatics are rad. Can do cool stuff with bleed valves to feather clutch engagement rather than slam it.

[Mike Sadie]

exFSAE

Do you know of anyone that sells reasonably sized electronically controlled pneumatic flow valves. I looked into those previously but never found an adequately sized one. Proportion-Air's valve is BA but also 10 lbs and 16 inches long.

http://www.proportionair.com/pdfs/literature/brfcv.pdf

[Chapo]

Thanks for the response guys
I have thought about using pneumatic clutch activation but I want to flexibility to be able to controll it / program it through our MoTeC and I feel that electronic would be easier for that purpose.
We currently run a pneumatic shifter with engine cut on the up shift (0.09sec) and the idea is to use the clutch for downshift and launch (both full throttle launch and a slow launch) just after posting yesterday I found a website for a company that makes pancake motors amongst other things (http://www.danahermotion.com) I was thinking a pancake motor with a threaded rod in the center, stop the rod from turning and you have linear motion of the rod http://fsae.com/groupee_common/emoticons/icon_biggrin.gif. you could intergrate that all into a nice housing and presto you have a clutch actuator.
Any thoughts?

Matthew Chapman
UNSW@ADFA

[Micko..]

Matt,

the electrical guys came up with using a servo motor from a remote control plane... i had lots of doubts about the claimed torques of these things but it worked well with minimal current draw (can't remember exactly). a filter to stop twitching would be good though.

hope that helps...

kirby... wasssup

[VFR750R]

not that i've done it, but hydraulics should also be considered. i think that's what F1 teams use. They have 100% duty cycle at full force, and can be more precise then air. You happen to have a hydraulic pump on the engine already. I'd look into an accumulator and or extra pump for engine safety but it can be done. A secondary pump would give you the ability to run much higher pressure then you'd want for the engine. Teams running dry sump pumps could use the pressure section for that and keep the internal pump for the engines high pressure oil.

[Kirby]

Originally posted by miko..:
Matt,

the electrical guys came up with using a servo motor from a remote control plane... i had lots of doubts about the claimed torques of these things but it worked well with minimal current draw (can't remember exactly). a filter to stop twitching would be good though.

hope that helps...

kirby... wasssup

Hey Mate..hows things?

Don't go spilling all our secrets(hmmm, your secrets now I guess I've defected)... http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Tintin]

Originally posted by VFR750R:
not that i've done it, but hydraulics should also be considered. i think that's what F1 teams use. They have 100% duty cycle at full force, and can be more precise then air.

F1 at the moment uses hydraulics for most actuators and the power steering and for exactly one reason: Power density. The forces needed to pull the clutch, load the diff or to provide steering assistance to the driver cannot be delivered by anything else (in case of the steering anything electronically controlled is verboten anyway).


You happen to have a hydraulic pump on the engine already.

I hope you're not referring to the engine oil pump, are you?


I'd look into an accumulator and or extra pump for engine safety but it can be done. A secondary pump would give you the ability to run much higher pressure then you'd want for the engine. Teams running dry sump pumps could use the pressure section for that and keep the internal pump for the engines high pressure oil.

Uups, you are appearently....;-)

The pressure needed to have decent actuator sizes is two magnitudes higher than what you're oil pump could provide. For a propper hydraulic system you need a hydraulic pump and high and low pressure accumulators (most hydraulic pumps suitable for this need a return pressure at the inlet to operate without cavitation). It's definetly far more work than an electric system or a pneumatic one operating and sizing the pump and accus is not an easy task. However if it's done properly than it's by far the most effective and versatile system. The current trend in automotive industry towards electric systems is mainly due to the fact that hydraulics are more expensive, more messy and oily during assembly and NVH is also problematic. In F1 that all doesn't count and comfort means the driver has to recover from a race before the next one ...;-)


Tim

[JaredC]

Originally posted by miko..:
Matt,

the electrical guys came up with using a servo motor from a remote control plane... i had lots of doubts about the claimed torques of these things but it worked well with minimal current draw (can't remember exactly). a filter to stop twitching would be good though.

hope that helps...

kirby... wasssup

Way to spill the beans.

We only use clutch for launch, so the RC servo worked well. With a pressure sensor mounted on a paddle we had full analog control over the clutch. I probably wouldn't like to use it on shifts, but we ran a slipper clutch to cover us for downshifts and ignition cut on upshift worked fine for us too.

The servo was good for around 6-8Nm off the top of my head, and there are bigger ones available.

[Chapo]

Which engine are you guys at QUT using, and what is the force required for your clutch pull?
We are using the GSXR600 and I measured the clutch force to be around 1KN and that is why I immediatly discounted the RC servo idea. However if you are getting that much torque out of one it could work. Just need a small arm....

[JaredC]

We have an R6. Off the top of my head it was somewhere around 180N on an arm that's maybe 4cm long.

I'd have to see if I can dig up my notes and working from last year though. It sounds very low compared to your 1kN figure.