Posted by Sherman in Idaho [72.47.153.105] on Sunday, October 20, 2013 at 16:55:15 :
In Reply to: OT whats old is new again posted by Kaegi [98.247.164.246] on Sunday, October 20, 2013 at 15:53:39 :
Didn't GM have the patent on the pinion/bendix type electric starter back in the day? So perhaps Dodge had to try a belt-drive system to get around the patent? Conventional "expert" wisdom in the early days of automobiles was than an electric starter would be impractical because in order to produce enough torque to turn over a gas engine, the electric motor would have to be as big as the gas engine. They solved that by using a small series-wound intermittent-duty high-speed electric motor with a large gear reduction. I'm thinking this new contraption would have the same problem, unless they only used it to start the gas engine when it was thoroughly warmed up and easy to crank.
As long as there have been vehicles with starters and generators, the engineers have toyed with the idea of combining the two. At first glance, it seems trivial, but as you look into it you find out that the requirements for the two devices are so completely different that it's very hard to combine them. The generator runs at moderate speed, continuous duty, light load, and efficiency matters. The starter runs at high speed, very intermittent duty, very heavy load, and efficiency doesn't matter. Or if you go for a combined starter/generator, they both have to run at roughly engine speed, which means a hell of a lot of torque in "starter" mode.
I'm almost wondering if for a "start/stop" car, an air starter system wouldn't be better. It wouldn't be too hard to keep some compressed air on board somewhere, add air solenoids to each cylinder, and have the computer inject air into each cylinder at the same time as it would fire the spark plug. Of course the mixture wouldn't fire with all that extra air, but it would get the engine spinning, and then when it stopped injecting air, it would keep going with the spark. If the air tank was empty, the computer could automatically revert to the regular starter.
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