TECH: Combined Starter/Alternator.......

[toysrus]

Here's another idea to throw amongst the wolfs LOL

The only thing I need to know is, does the gear/windings move into position along the Flywheel ring gear when turning the key to 'accel' or is it fixed ?

I would have to make up a circuit and even then I think the current output would be just a tad on the low side....but we'll see what I can come up with :P

I may just make the Alternator the Starter instead too but I'll play around with the idea and pros/cons of either in my head for a while.....

Thanks !

[scum]

go to a motor museium.. called a startnator or some crap.

[Alspos]

This has been done on a few concept cars also. I daresay you'd need some sort of step-up arrangement to get enough torque to start, then the gear drops out and the rest spins at normal speed.

[jakobsladderz]

The action of the starter accelerating flings the gear into contact with the ring gear (plus the solenoid has something to do with it). Starters run on upto 100-150 amps and are only able to get the engine spinning at around 100-200RPM. I would suggest that full rev motor speed through the ring gear would tear the innards of a starter to pieces.
Alternators on the other hand run up to 60-70 amps and are happy up to full revs of the engine. Unfortunately, they are essentially AC devices internally (hence alternator) so to get them working as a motor you would need a three phase inverter capable of the 100-200 Amps to start the engine. Their construction would mean they were unable to provide much torque and the belt drive would not be able to turn a motor over without some mods (maybe a toothed belt would solve that, but the sizing is still wrong)
The recent versions that I have seen are designed for hybrid vehicles and basically use instead of a flywheel and ring gear an armature (middle bit of motor/generator). to start the car and provide motive force it's used as a motor (taking current from battery). During regenerative braking and to charge the batteries it's used as an alternator.
See, if the windings are of an appropriate size to start the car, then they're well oversized to use purely as an alternator (at the same drive ratio), but they suit a hybrid drive system down to the dollar.

[toysrus]

The action of the starter accelerating flings the gear into contact with the ring gear (plus the solenoid has something to do with it). Starters run on upto 100-150 amps and are only able to get the engine spinning at around 100-200RPM. I would suggest that full rev motor speed through the ring gear would tear the innards of a starter to pieces.
Alternators on the other hand run up to 60-70 amps and are happy up to full revs of the engine. Unfortunately, they are essentially AC devices internally (hence alternator) so to get them working as a motor you would need a three phase inverter capable of the 100-200 Amps to start the engine. Their construction would mean they were unable to provide much torque and the belt drive would not be able to turn a motor over without some mods (maybe a toothed belt would solve that, but the sizing is still wrong)
The recent versions that I have seen are designed for hybrid vehicles and basically use instead of a flywheel and ring gear an armature (middle bit of motor/generator). to start the car and provide motive force it's used as a motor (taking current from battery). During regenerative braking and to charge the batteries it's used as an alternator.
See, if the windings are of an appropriate size to start the car, then they're well oversized to use purely as an alternator (at the same drive ratio), but they suit a hybrid drive system down to the dollar.

That makes sense :beer

The inverter would kill the weight saving gained........but you could reduce the current being sent back easily enough again at the loss of extra weight

On a side note, I noticed how an Auto VR4 Starter (the one which was in my Cordia) is smaller and I bet weighs less then the Cordia Starter :P

Would be interesting to see how small/light you could go with starter motors though :drool:

[Alan]

Most modern cars (including the Starion) use a pre-engaged starter.
When the ignition switch is turned to Start,
this provides an electric current to the Starter Solenoid,
the Soleniod moves the Starter motor drive gear into mesh with the Flywheel ring gear.
Once these gears are physically in position a set of contacts are closed inside the starter motor which allows current to flow and the starter motor to drive.

[jakobsladderz]

Cool, wasn't 100% on that. Do they disengage permanently once the engine fires or does a spring bring it back in touch? I would figure the latter by the sound..

[Alan]

The gear on the starter motor shaft is attached with a one way clutch.
When first starting the engine the starter motor shaft turns and the clutch drives the starter motor gear.
When the engine fires and is running, it is then trying to drive the stater motor faster than it is designed to run.
The clutch in the starter motor gear allows the gear to now turn faster than the starter motor shaft, effectivley freewheeling.
Just like a push bike. When you are coasting down a hill the rear wheel doesnt drive the pedals around.

When you release the ignition key from the start position, you de-enegise the starter solenoid, and a spring withdraws the drive gear from the ring gear.

Alan

[scum]

http://www.popularmechanics.com/automot ... 66776.html



meh...