Electric Starters... do we still need them?

No. You need the rotation of the crank to compress the air fuel mixture. You could fire a plug after you inject fuel, but there would be no explosion.

 

The engine management systems need to see the engine turn for a couple of seconds to figure out the position it is in. None of that stuff works when its not turning. Carb motors will actually start quicker when in good tune because of that. A carb and points motor can actually start during the first revolution.

 

A bit of trivia; The idea the OP is describing is "starts on the button" the term comes from the dawn of the automobile before self starters.

Once in a while, when an early car was shut off, and the engine stopped with a piston in just the right spot, AND it had only been a few minutes, you could just turn on the ignition switch and the car would start itself like magic. I had a 1912 Chalmers that would do it about 10% of the time, and it was always worth a try before getting out and cranking.

Cadillac perfected the starter motor in 1911 but all sorts of crude self starters were used. How about a compressed air starter? All you did was turn a valve that injected compressed air into the appropriate cylinder.

 

Hybrids can eliminate the alternator.

There are also "start-stop" vehicles that will shut the motor off at stop lights, etc. to save fuel. These vehicles generally have more robust starters and batteries.

 

You have a hard time grasping a lot of things. Did you even read what I wrote?

Please, it won't work for a number of reasons. Read up on how it all works. Even if what you want to do was possible it would start a fire, not an explosion.

 

Do we still need a starter motor? Yes.

https://www.etas.com/data/RealTimes_2006/rt_2006_01_34_en.pdf

 

Combustion IS possible but without a compressed mixture it would be a comparably small amount of power. Enough to turn the engine into the next compression stroke? I don't know but have heard/read it's possible.
Crankshaft positioning could be determined.
Aha, just saw the above article

 

True and in old 5:1 compression motors it was done, quite often actually but not modern motors. It would require significant redesign and for the elimination of a $10 starter motor you need to ask why.

 

I have witnessed model Ts (or was it an A?)started by simply moving the timing adjustment lever on the steering wheel. I was told it was a fairly common practice back then but the engine needed to have been recently run for it to work.

I wasn't asking why, just speculating how or if it can be done. But since you bring it up. Eliminating a starter motor would be less mechanical things to fail, eliminate a reasonably heavy electric motor and allow for smaller packaging so, yes, good reasons to try.

 

It's theoretically possible, and could perhaps be achieved in the near future.

Requirements would be:

- direct injection engines only
- ECU has to know, before the engine is running, the exact crank position so it can derive which cylinder is on a compression stroke
- a cylinder has to be just past the top of travel with valves closed and compressed air still present in cylinder (so that an ignition event pushes the piston down in the correct direction - if a piston was just prior to the top on a compression stroke, then an ignition event would drive the engine backwards).

In that specific scenario, a really smart ECU (none currently exist or are programmed for this) could spray a fuel charge into the cylinder full of compressed air via the direct injector, then spark it off.

You'd have one chance for this to work, if the engine didn't start and you didn't have a cylinder just past the top of the compression stroke with compressed air, you wouldn't have a second chance. Care to gamble on not having a starter?

Far more likely than eliminating a starter motor, would be to use this technology for engine stop/start systems where a direct injected engine is warmed up, the computer is booted and knows the crank/cylinder positions, and the cylinders on a compression stroke have compression because the engine would only be stopped for seconds, minutes at most. It might be tougher for a 4 cylinder engine where it's less likely that you'd have the one cylinder on a compression stroke just past the top of the compression stroke, and not halfway. Best use, then, might be on a 6 cylinder or V12...

 

I eliminated the starter motor in my QV after wiring in a starter button to rework immobiliser issues and then leaving the switch 'on' whilst driving - ouch!!! In the interim period of rebuilding my SM, I covered nearly 400 miles, by parking on hills nose down!!!
Not sure weight loss and performance BHP/tonne gains cancelled out 'fear of stalling', Estes fuel use at junctions (from revving) and inconvenience!!!

400 miles included refuelling and finding people to push! Surprisingly easy.


Sent from my iPhone using Tapatalk

 

My Mercedes does this and it drives me crazy! I wish I could by-pass that crap. The car will turn off at the gate to my neighborhood. The car will turn off when I pull into the garage, then when I turn it off, its starts so it can turn off. Yes there is a button to turn this system off but it's tough to remember to do it each time till I am sitting at a stop light and the car starts up, shakes and scares the crud out of me. Stupid system and the car seems to get the same gas mileage whether its on or not.


End rant sorry for the thread hijack......................

 

that's funny!

 

Another well intentioned but poorly though out device to lower emissions. Those who dream it up need to be taught the rule of unintended consequences. I can see doing it with a hybrid whose electric motor can be used to start off from stops but not on this car.

 

Do we need them? Yes because the alternatives, even if cool, just don't compare for ease of use... https://m.youtube.com/watch?v=vb0-br7hTw0

 

It is on my 2015 VW Golf (gas). I just turn it off as my first systems-check after starting the car. It will DRIVE ONE NUTS. IMO, it is a throw-back to East Germany and the 2-cycle Trabant.

Just thinking, wouldn't 'firing' the motor with the crank at a dead-stop really tear-up the crank itself or bearings faster vs. a pre-spinning motor due to a starter?

Perhaps mis-equating this to TOP FUEL Drag Racing. You DO NOT start a TF motor on NITROMETHANE, the actual fuel it burns during the race. You get the motor spinning/firing first with the starter and alcohol.

 

That reminds me of an old movie:

https://www.youtube.com/watch?v=IACjOvyx5hs


Coffman starter

https://en.wikipedia.org/wiki/Coffman_engine_starter

 

The alternator has nothing to do with starting the engine up, so what is the relevance of this statement?

These vehicles have to have more robust starters and batteries because of how much more work they have to do compared to cars without stop-start technology.

Added to that, cars with stop-start technology continually monitor the loading on the cars electrical system and the state of charge of the battery. Should the loading be too high, or the battery charge be too low then the stop-start system is temporarily disabled until the the loading or charge level is more suitable.

More robust as they might be though, the cars with stop-start systems still rely on traditional based starter technology.

 

And ... many (some) cars have dual battery systems for their start/stop capability. For example, the Chevy Malibu with start/stop technology has a second battery in the trunk. The second battery is used to power electrical accessories including climate control at stop. But, the climate control operates at reduced power when the engine is off.

The inclusion of start/stop technology in cars will cause degradation of the battery in short order when the car is not driven long enough between starts to adequately recharge the battery(ies). Hence, the reason many cars include the ability to monitor the state of charge of the battery(ies).

There are other changes coming to vehicle electrical systems due to the many power hungry accessories that are being added on:
- Li-Ion batteries
- Dual battery systems
- 48v battery systems or hybrid battery systems with a 12v battery and a 48v battery circuits (100% 48v is slow in coming because so many 12v components on cars) ... 48v systems will reduce the amperage draw for any given power requirement.
- Tandem-solenoid starter systems to provide faster restart times
- Use of large capacitors to provide quick energy during auto-start (e.g., Cadillac)

Steve

 

Crank position IS known of course. Just read/use a sensor which reads degrees off of some sort of pulley, or, easier, remember it from when it was running last time, i.e. When it was shut off.

So that is not the issue. Uncertainty about how much force the fire will generate and if it is enough to rotate the crank is.

Other ways: not turn of the car by cutting power, but in a different way. I can think of some ways though, but not viable.

 

It was designed to confuse you.

 

Some military vehicles have had inline starter/generators for awhile now. A heavy but good solution if you need a lot of power generated and saves space underhood.

With regard to starting via spark and direct injection. Not sure it would work on a 4 stroke due to valve train friction, but SkiDoo introduced just such a system on their 2 stroke snowmobiles this year, the SHOT system. 2017/02/15 Note: SHOT does us the magneto as poor starter motor to start the spin-up.

So the OP's questions are not out of the realm of possibility, the tech's just not quite there yet.