This is probably already revealing how old some of us are, but we remember that we had to start our cars by turning the key and waiting to hear the engine “catch”. At that point you knew the engine was ok to proceed, and if you stopped turning the key it wouldn’t die.
How does the starter today (push button) know all this, and it never seems to get it wrong? I have never heard a push button starter fail to get it right unless some other issue like dead battery, etc. (and btw, today’s engines seem to have so far fewer issues like we used to have)
In: Engineering
“Used to”?
You can pry my physical key from my cold, dead hands.
How do you hear the engine catch? You have sensors (ears). Same for the car. It might be looking at a sudden change in crankshaft speed, manifold pressure, fuel flow, oil pressure etc. Once it sees the conditions the engineers programmed it to react to, it stops cranking.
It goes back before push to start vehicles. My 2011 Chrysler 200 has a traditional chip-key, and you turn it past “on” to “start” and let it go immediately.
Remote starters do the same thing too but yeah, the computer, often called ECM or Engine Control Module. All the sensors feed into it including things like crank position, throttle position, and Mass-air flow sensors.
Starter motor is there to get the engine spinning fast enough to start combustion, once ignition happens, there is a jump from max starter speed to minimum idle speed. Just watch the crank or cam sensor output to see rpm’s raise
It’s simpler than all this ECU stuff. The starter motor output shaft is threaded, (inertia system or “bendix gear”) then a small gear is threaded onto that, then that small gear interfaces with the flywheel on the engine. When the starter motor is engaged and the engine is off, the starter motor shaft is spinning faster than the little gear, so it winds its way down the shaft, until it engages with the flywheel. Since the starter shaft is pushing on the small gear, it stays out at the end of the threaded shaft. As soon as the engine turns over and starts running, the flywheel speeds up. Now the flywheel and the little gear are spinning faster than the starter motor shaft, and the little gear winds itself the other direction back up the shaft until it disengages itself from the flywheel.
No computers or sensors or anything, the starter motor little gear just disengages itself from the flywheel any time the engine is running.
More research shows there are several ways to accomplish this. Above is one, another is using active means to move the small gear in and out, also there can be a free wheel clutch on the starter.
https://www.howacarworks.com/basics/how-the-starting-system-works#:~:text=Also%2C%20if%20the%20engine%20starts,starter%20is%20turning%20the%20engine.
Regarding your last sentence, modern manufacturing processes made a lot of improvements to ICE in general.
With old cars you had to change your motor oil for the first time shortly after purchase and you were told to drive sedately for the first 1000km or so.
Today the inside of your cylinders is honed to a very precise degree both in surface roughness and diameter, and the piston rings are coated with chrome or ceramics. So today there is no more early first oil change.
And thats only one example 🙂
Consider that the range of possible starting RPM’s and the possible running RPM’s do not overlap at all.
wtf? Tons of cars still use keys…
I would like to know how a push to start handles a situation where, maybe it’s incredibly cold out and the engine doesn’t quite turn over like it normally would. My old Mazda 626 always had issues with the battery getting so cold that I’d have to give it a couple seconds to actually turn over enough to get started.
The big thing is fuel delivery. Today most vehicles with push button ignition are either multiport fuel injected (with the injection sitting right at the intake valve stem) or directly injected (injector is in the cylinder). No more need to draw an air/fuel mixture through the intake manifold or even as far away as the throttle (carbureted and throttle body injected engines). As long as the injectors are primed you are pretty much guaranteed to have successfully ignition on the first cylinder to go through the intake and compression stroke.
Modern engines are also capable of detecting misfires as they happen so it’s fairly easy for a smart starting system to only run the starter enough just to get things going while knowing when to detect when the engine is also running and not just fired on a single cylinder
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