Clutch pedal as regenerative brake control

Technical discussion on converting internal combustion to electric
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juk
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Clutch pedal as regenerative brake control

Post by juk » Fri, 02 Jul 2010, 19:05

Would it be feasible to leave a clutch pedal in, wire it up with a hall effect sensor and use it to control the amount of regenerative braking?

edit: typo
Last edited by juk on Fri, 02 Jul 2010, 20:20, edited 1 time in total.

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woody
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Clutch pedal as regenerative brake control

Post by woody » Fri, 02 Jul 2010, 20:13

Yes. You'd need a decent return spring.
For a mechanical linkage you could find somewhere to attach an (e.g. EVworks) hall effect box.

You could reposition the clutch slave cylinder (for a hydraulic clutch) to somewhere where you could attach a potbox.

(does anyone do hydraulic clutch linkage anymore? my cortina is hydraulic)

On the controller side - it depends how they accept regen demand input - but you could probably electrically do whatever was needed it with a simple circuit.

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Clutch pedal as regenerative brake control

Post by EClubman » Fri, 02 Jul 2010, 20:31

Technically speaking, yes you can turn your clutch pedal into another brake pedal.

From a user interface (and car safety) point of view, it's probably not a good idea.

Changing the function of a regularly used control to do something completely different, especially if someone unfamiliar with your car is driving.

Imagine the scenario:
Newb driver in your car, you in the passenger seat.
Newb goes to start, puts their foot on the clutch, lets it out as they accelerate - no probs.
You remind them that the clutch is actually a regen brake.
They go to change up gears, foot on clutch, whoops, foot back off, that's right, it's a brake.
Keep driving for a couple of minutes - no probs - come up to a big road, need to speed up to merge, go to drop down a gear, foot on clutch, BANG, get rear ended by the car behind that was also speeding up.

juk
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Clutch pedal as regenerative brake control

Post by juk » Fri, 02 Jul 2010, 21:50

Woody, it's a hydraulic clutch, obviously the master cylinder is going the way of the slave cylinder. So i'm good there, and there's a hole through the bulkhead for the master cylinder which i can utilise.

EClubman, you make a good point. So it would need a lockout, that's normally locked. Besides, nobody else drives the lotus but me. Especially after i've spent a few tens of thousands of dollars converting it.

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Clutch pedal as regenerative brake control

Post by 7circle » Fri, 02 Jul 2010, 23:34

I like the idea of the lock out for untrained drivers for the clutch, thats if it can be effectively controlled after many hours of practice.
(I remeber even getting used to changess in indicator stalk side when changing cars often with in a day, turning the wipers on by mistake)

I would still like the accelerator to provide some motor braking/regen.
So combining the clutch and the accelerator with a dash dial (tight to loose/ lockout). Looks like mapping out expected preformance with 3 inputs could be difficult.

Also what happens if you push the clutch while the accelerator is still pressed. Which one over rides/priority.
OR is it just like the dash dial modifying the the behavior of the accelerator pedal.

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woody
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Clutch pedal as regenerative brake control

Post by woody » Fri, 02 Jul 2010, 23:57

Mark - good point.

For this and other "unnatural" controls they should reset to "natural" at startup, and experienced driver can switch toggle "expert" mode with a push switch.

"natural" for a clutch pedal would be "kill the accelerator" for most conversions
"natural" for the accel pedal would be "minimal / no regen braking and moderate performance"
"natural" for the brake would be "slow the car down" :-)

In "expert" mode you can go nuts, but you'll be messing with your subconscious driving skills and you'll probably stuff up if you get in a hairy situation in your EV or another car.

(e.g. switching between Jap + Euro cars you wash the windscreen instead of indicate)

(although despite driving a column shift I rarely rip the windscreen wipers control off the column in my "other" car)

cheers,
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Clutch pedal as regenerative brake control

Post by zeva » Sat, 03 Jul 2010, 00:39

We looked into the idea of using the clutch pedal to control regen level a while back, and according to the WA licensing department it would actually be illegal and they wouldn't pass it! In fact here in WA, we're legally required to remove the clutch pedal if it isn't being used as a clutch (e.g clutchless conversions, direct drive conversions, etc)

Also IIRC we're only allowed to use regen in a similar fashion to engine braking, i.e a modest amount of regen kicks in when one's foot is off the accelerator pedal, and not controlled by the brake pedal. I hope this changes though because non-wearing electromechanical braking could largely replace friction brakes in the future.

For interest, Formula SAE Electric (track cars not road cars) stipulate different behaviour: "The first 50% of the brake pedal travel may be used to regenerate brake energy. The brake energy recovery is only permitted when the brake pedal is actuated by the driver. Automatic brake energy recovery is prohibited. The remaining brake pedal travel must actuate the hydraulic brake system."

Personally I'd like to see a combination, i.e a small amount of automatic regen whenever the foot is off the accelerator, AND use the first part of the brake pedal's travel for (more) regen.
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Clutch pedal as regenerative brake control

Post by acmotor » Sat, 03 Jul 2010, 01:43

I second that last statement.

There is also the prius 'first part of brake pedal for regen' well established. This meets the existing driver expectations.

At some stage though, regen to replace all(?) normal braking will dominate.
Shifting the foot from accel to brake has long been a time delay added to braking distance. Perhaps there will be another control option become standard ?
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Clutch pedal as regenerative brake control

Post by Simon » Sat, 03 Jul 2010, 01:47

zeva wrote:
Personally I'd like to see a combination, i.e a small amount of automatic regen whenever the foot is off the accelerator, AND use the first part of the brake pedal's travel for (more) regen.


Yes this is what the Prius does and is it works well. Getting the transition smooth and seamless from regen to mechanical braking could be fiddly for us DIY EV converters though?
And add a switch to turn off automatic regen would be nice too.

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Clutch pedal as regenerative brake control

Post by woody » Sat, 03 Jul 2010, 02:58

acmotor wrote:Perhaps there will be another control option become standard ?
I thought a long time ago that just one pedal, "brake" would work - i.e. the car feels like you are rolling down a steep hill and you just "brake" less to accelerate, more to slow down. The bottom part of the travel would be your traditional brake.

Obviously you need some other sort of input to turn on the accelerate, (so you could take your foot off the brake) but you have a spare foot to push a button like that.

This could be implemented in a petrol car... or electric..
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Clutch pedal as regenerative brake control

Post by 7circle » Sat, 03 Jul 2010, 03:20

The ICE braking is very effected by RPM and gear selection. More so in diesal. Also CVT engine braking would feel different again than Auto or Manual.

"Regen Brake Control" is unclear.
I think the main idea of Juk is to have full motor braking on a seperate pedal. Like the hand brake can be used.
Brake bias to front rear is an issue to.
Front / Rear/ All wheel drive lots of possible applications.

I know of many people who use left foot for braking in Auto's. (Not good for many reasons)
Just tring to point out how cars are driven can be quite different.
Steering Paddle switches for gear selecting too.

I'm not to convinced that I would want to use my left foot for this function. I tend to think that have a dial or level selelctor and only using the accelerator position to control speed.

Having the car perform like its a high reving ICE in 2nd gear.
I'm sure this has been covered before, so after think I'm not adding much to the post,
I must add that I'd really like to hear what it is like to drive with an extra left foot brake.
I used to wonder about 4 wheel steering intergrated into the controls.

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Clutch pedal as regenerative brake control

Post by juk » Sat, 03 Jul 2010, 06:25

Thanks for the responses guys. Seems like another good idea has gone the way of the dodo. The lowest common denominator is pretty damn low eh?

I'm determined to have variable regen at some point even if only for on the track or closed roads as the case may be.

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Clutch pedal as regenerative brake control

Post by 7circle » Sat, 03 Jul 2010, 10:03

Just noticed this guy is using the Clutch for regen control ....
But its on a Motor Bike
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