Automated engine-off coasting..

[akumabito]

I wonder if anyone has experimented with this yet.. in most modern cars, pretty much everything is governed electronically. I am just curious how feasible it would be to have an electronic controller do all the 'hard work'.

Say you're on a road with a 50mph speed limit. You could have a controller gently accelerating the car to 55mph, engage the clutch, turn off the engine, let the car coast to 45mph, restart the engine, disengage the clutch and gently accelerate back to 55mph. Wash, rinse, repeat. Kind of like a hypermiling cruise control.

Of course its practicality might be limited to roads with little other traffice, but the concept sounds neat in my mind..

Has something like this been tried yet?

[skyl4rk]

I have thought about hacking something like this. My Versa has a drive by wire system, and I believe the throttle is controlled by voltage level, 0 to 5V. I would like to put together an algorithm that inputs rpm, engine load and mph, and outputs an ideal throttle position. When I get to 5th gear (top gear), I would press a button to accelerate using the algorithm, and then at the target speed, press another button to kill the motor, and manually disengage the gear, using the clutch if necessary.

Your idea automates more of the process, but I think I could actually build a system that automatically throttles up to a target speed in high gear. The algorithm could be modified and experimented with to find the optimal curve.

The automated system would make doing 35-50mph EOC very easy, and every pulse would be using the most efficient throttle method that you could work out by experimentation.

[justjohn]

Very cool idea. I don't know enough yet to try anything like it myself, but I support this thread.

[Joenavy85]

great idea, though i don't think it would be very easy to incorporate into a car, you need the second computer to control the clutch, the starter, as well as the throttle and coordinate all of them properly. yes you could build a computer to do it, but it would be hard to incorporate it into a vehicle

[RobertSmalls]

There are some big issues with an automated P&G setup. For one, you'd need an actuator to shift into and out of Neutral. If you just had an actuator on the clutch, you'd put undue wear on the clutch release bearing. Another issue is hills and traffic. A human driver is so much better than an Arduino at anticipating good coasting opportunities.

One thing that is on my to-do list is to rig up an automatic kill switch, so that every time I shift to N for more than 500ms, the engine dies. That would make P&G as easy as: pulse, shift to N (engine dies), glide, tap the throttle (engine restarts), shift into gear, repeat.

The Insight makes this an easy project, because it has a sensor that reports when you're in Neutral, and it already has engine restart logic programmed for you. It might be harder to detect Neutral on other cars. You can't rely on the clutch switch, because it's only closed when the clutch pedal is all the way to the floor.

[akumabito]

Originally Posted by RobertSmalls

The Insight makes this an easy project, because it has a sensor that reports when you're in Neutral, and it already has engine restart logic programmed for you. It might be harder to detect Neutral on other cars. You can't rely on the clutch switch, because it's only closed when the clutch pedal is all the way to the floor.

Good points all around.. I'm thinking this might be easier on a motorcycle-powered car: after all, motorcycles already come with a neutral indicator.. Shifting from 5th or 6th down to neutral, then back up again for when the engine restarts is a pain in the butt though.

Are there any workarounds to the clutch bearing issue?

[dcb]

Originally Posted by akumabito

...
Are there any workarounds to the clutch bearing issue?

Yes, and it is appropriately complicated.

You need to add solenoids that can put your transmission in any gear or in neutral (reliably) or just focus on top gear for now.

You also need a vehicle speed sensor

And you need an rpm signal

And you need to know the RPM to MPH ratio for each gear you want to automate.

And you need to have a way to control the throttle (of course) by automation.

And you need to have a way to kill the engine by automation.

And you need to have a way to start the engine by automation.

And you might want to have a reading on manifold pressure.

However, unless you are at a complete stop, you do not need to do anything with the clutch.

So to initiate a glide, your robo-shifter would:

"unload" the engine so it could slip the transmission into neutral, i.e.
a. if the engine is providing torque then kill it and while there is slack in the driveline slip it into neutral.

b. if the engine is in overrun (high vacuum) then give it some gas to load it, then kill it and slip into neutral.

c. ensure engine is killed.

To initiate a pulse, your robo-shifter would:
a. start the engine

b. examine vehicle speed

c. determine appropriate gear selection

d. bring engine rpm up to the precise speed needed to slip the transmission into the next gear.

e. start accelerating at most efficient rate.


And of course you want to think about how much pressure your robo-shifter should apply and when, perhaps with pressure feedback, and expect many experiments (broken bits) while you get it perfected. It also will work better with more vss (vehicle speed sensor) pulses per revolution, i.e. perhaps an ABS sensor might be a good choice.

[akumabito]

Not impossible, but beyond my skills, sadly..

I do hope someone more tech-savvy can experiment with something like this..

[Daox]

Here is the next closest thing: http://ecomodder.com/forum/showthrea...top-16395.html

Its still a work in progress, but should hopefully be working soon.

[dcb]

Originally Posted by akumabito

Not impossible, but beyond my skills, sadly..

I do hope someone more tech-savvy can experiment with something like this..

I look at what is involved and I appreciate manual shifting and a kill switch all the more Especially since I have a built in clutch controller as well.