Stop-Start Automotive Technology

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Stop-Start Automotive Technology

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Start-Stop Technology Becoming Mainstream

First, let me say, Thank you, Lyn!!!

And, second, please accept my humble apology. I should have known better to check for previous posts on CR4.

No apology necessary.

This idea sounds as though still in infancy, and thus suitable for further experimentation and optimizing. If there are many stops/starts in close succession, a heavier-duty battery may be in view, but the control system could compensate by not stopping the engine if the battery charge is marginal.

Deciding what condition, or combination of conditions, should trigger an engine shutdown could be interesting, or even thorny. If you get involved in this, periodic feedback would be nice.

Heck, I shut off the car when I am in a lineup at Mickey Dees! Its the law in Toronto...you can't stop by the side of the road and eat your hot dog with your car running.

Let me see if I got the logic right:

IF: Car stops for any reason and the brake is depressed then engine stops.

IF: Brake is released then engine starts.

Seriously, on gasoline/diesel engine driven vehicles?

It would work well with electrically driven vehicles but I can think of at least 20 real world driving situations where this algorithm would be disastrous not only to the vehicle operator's safety but also to everyone around them.

Besides; If we can't even keep a simple Cavalier in good enough condition to start and operate dependably how could we possibly maintain such a complicated control system?

Imagine a world full of stop lights, railroad crossings, pedestrain crossings, school crossings, and stop signs with thousands of vehicles stalled in every major city at every one of them.

Not exactly. Foot off accelerator, power to ignition cut.

Foot on accelerator engine restarts.

At least that's the way it works on golf cars.

It's been around for years: #16

Yes, but golf carts aren't out on the roads in traffic nor operating in inclement weather.

What about driving on icy, snowy, or wet roads when your foot is off the accelerator pedal but you still need power assist steering and/or traction control or have to apply the brakes?

Going down steep terrain on a winding road?

Traveling on a 75MPH freeway in heavy traffic and you inadvertently take your foot off the accelerator? (How would the logic know what is happening?)

I have no doubt that with extensive, expensive programming that a vehicle could operate as such.

However; once the vehicle gets wear and tear on it the incident of failure and vehicle stalling will increase dramatically.

I can't get my son-in-law to keep his battery terminals clean which is a very simple inexpensive but critical task.

I can't count the number of times one of his vehicles has broken down and dirty battery terminals were the cause.

I am firmly convinced that our technological capability is far outstripping the general populace's IQ and their ability to cope with the results.

A case of this is being brought forth by the extensive research on satellite controlled vehicles utilizing GOOGLE.

I cannot count the number of times Map Quest, Google, Tom-Tom and other satellite driven vehicle routing software has given wrong directions to our drivers, myself included.

Routing a semi or any other vehicle through 7 miles of downtown traffic instead of maintaining a route on freeways and/or business bypass loops is insane but it happens way too often unless a knowledgable driver overrides the equipment.

Imagine being in a vehicle that is being automatically satellite controlled by Google, you cannot alter the route, and you start having issues with engine stalling in rush hour traffic.

You are worrying for no reason.

Such systems have been around for probably 20 years or so.

A small processor makes all the important decisions, it works well and with most cars, saves fuel.

The first time you drive one, it is unnerving for the first few stops.

Such cars not only have an intelligent processor to control it, but also have a beefed up starter motor of higher, longer lasting quality. They also have a bigger battery and a larger alternator for faster charging......

I have covered in in a very simple fashion by the way, so that its easy to understand....I personally would not like to design and build such a system......but combined with an automatic gearbox it works well.

With manual boxes, as soon as you put it in gear, the engine starts.....Minis for example.

It is no problem at all as long as its not a Chevvy!!!

Go to a golf course, ask the cart master.

This technology is used quite a bit in Europe. And used on some cars here in the US.

The idea is that when the car is stopped with the brake depressed, the engine shuts off. When the brake is released, the engine restarts. This is meant to happen even before you move your foot to the accelerator. Approximately a 300ms restart time is required which sounds impossible but is doable.

One idea is to have the starter pin engaged when the car engine stops. And possibly stop the engine with a cylinder precharged ready for a spark. But this requires a much more durable starter to be able to last maybe 300,000 cycles instead of a typical 30,000 cycles.

Maybe have an electric motor in line with the engine that can turn the engine quickly and then be used as the alternator during normal operation.

I'm not sure how well these systems will work and whether it will be worth all the extra technology and cost.

Here is s press release about the FORD start/stop:

Ford Motor Co. says it will offer an automatic engine stop-start system in 70% of the models it sells in North America by 2017.

Stop-start systems shut off the engine when the vehicle stops and instantly restarts it as the driver releases the brake. Ford currently offers the option in the U.S. only in 2014 Ford Fusion small sedans equipped with a 1.5-liter EcoBoost 4-cylinder engine.

I would think that with the current OBD2 ECM programming having the ability to know and monitor the exact position of all pistons at all times would allow elimination of the electric starter motor entirely.

Surely the control could pulse the correct fuel injectors for all pistons at or near the top of the compression stroke then appropriately activate the ignition spark modules for those cylinders to cause fuel ignition and thereby result in crankshaft rotation.

I am very curious as to the mechanical and electrical controls logic operations for this type of control.

Anyone have any links or documentation available?

There a reason that the fuel is injected during the intake stroke. How much pressure would it take to inject adequate fuel at top dead center of the power stroke; even if there was enough air for explosive combustion?

When an engine sits does the cylinder pressure leak out of the pistons that are near top dead center of the compression stroke? If so then would there be enough air to facilitate adequate combustion to overcome the compression of the other cylinders?

IMHO - In Hybrid Power Processes, if start/stop methodology is used then the prime mover is oversized and/or power production is not properly processed. See " The Three Fundamental Efficiencies of Hybrid Technology."

Good points!

I am sure at least a portion of the cylinder pressure would be lost and the longer the engine is off the more loss of pressure there would be therefore the starter motor could not ever be totally eliminated.

In the case of a vehicle stopped at a traffic light with the engine off the cylnders that were/are in the firing stroke would already have the correct charge of fuel and oxygen in them.

If the vehicle did not sit for too long of a time I wouild think it would only be necessary to actuate the igniter and add inject a very small amount of fuel to create the richer starting air-to-fuel ratio required to provide enough torque.

However; I also believe that if we have the technology to make elimination of the starter possible it most likely would have already happened.

Thank you for the good information and the reference material.

HAPPY HOLIDAYS!!

Some misunderstandings here I feel.

When a gasoline motor is stopped, the supply of fuel is also stopped as well. There is no fuel sitting in any cylinders waiting to burn, unless you have an engine of at least 40 - 50 years old.....this stops the seepage of fuel down the cylinder walls and the fuel ending up in the sump oil....especially on cars used only for short running, that never achieved a proper temperature.....

When slowing down/Braking even on most cars today, no fuel is supplied to the motor till it is almost at tick over, and when in gear, going downhill, probably not even then!!!

It has already happened!!!

Starter motors have been eliminated in certain engines/vehicles, where a large electric motor is also used for propulsion, as this motor can do several jobs - Moving the car under battery power alone, working as a generator/alternator to feed power back to the battery when braking and "over running" and starting the IC engine to charge batteries or to give an extra turn of speed.

Modern clever electronics manage that all!! What I have written is probably not the whole story either!!

Hey Andy, I just heard something I would like to see if you can confirm.

I was told that the German Smart car is running a MB 3 cylinder clean burn diesel that gets over 60mpg and produces less emissions than the gas engine version.

Over emissions I cannot say much, but we have many diesel cars that achieve such economies with fuel....not just tiny cars like the Smart either!!

I will check around for you.

I hate Smart cars, especially when a truck is driving behind me......driven them many times, hate it still....

I don't think so because the fuel rail is mechanically pressurized at all times even when the car is stopped and the injectors are opened allowing fuel to be sprayed into each cylinder before the piston(s) reaches the top of the compression stroke.

Shortly after the fuel is sprayed into the cylinder and before the cylinder reaches top dead center the igniter/spark plug is activated/fired.

This is done so that maximum fuel oxidation occurs and the resultant explosion generates maximum pressure in the cylinder to obtain higher horsepower/torque for the quantity and type of fuel being burned.

If either of these steps occur too early in the combustion cycle detonation occurs (knocking sound) and severe engine damage can/will occur.

OBD engine controls utilize on board knock sensors to detect this phenomonon and advance or retard the timing of the fuel injection pulse width and igniter activation as needed to maintain maximum fuel oxidation efficiency.

There would be no way that when the ignition is suddenly cut off there would not be some unburned fuel left inside some or one of the the cylinders.

When the car is stopped the residual amount of unburned fuel would be minimum because the engine has been reduced to an idle hence the reason for added fuel pulses to enrich the environment and allow proper/adequate combustion.

Years back I worked with some of my wife's cousins in developing a fuel injected engine that would run on any combustible chemical and the residual unburned fuel left over in the cylinders was a real problem with controlling ignition of some of the combustibles tested.

After many months of R&D the engine was a success and the technology is currently used in many (most) new military vehicles in today's world but it has been dramatically refined and improved.

I am anxiously awaiting what the future holds in automotive and HD engine/vehicle technology breakthroughs.

I am very sure that much of what we perceive as technological barriers and/or impossibilities will be decimated in the very near future and the results will be astounding.

This is a silly statement:-

There would be no way that when the ignition is suddenly cut off there would not be some unburned fuel left inside some or one of the the cylinders.

It shows that you did not read and or understand what I wrote.

I will try again,just for you, but if you don't still understand it, its your problem, not mine!

In a car engine fitted with injectors, they are simply "not enabled" when fuel should not be burnt. No fuel gets into the cylinders.

Switching off the engine is a prime example. The reason that the engine stops is because of no fuel being injected, not no sparks.

Furthermore, almost no engines stop immediately,they may turn over another 50 times before stopping.

Even if the injectors shot a "last" shot that was not burnt, this would have been "scavenged" away......

THERE IS NO UNBURNT FUEL LEFT IN A MODERN ENGINE AFTER STOPPING IT COMPLETELY!!!!!

Nowadays, engine manufacturers save fuel at every opportunity to make engines as economical as possible.....