Quote:
Originally Posted by Piotrsko
Why even care if the motor spins or not? Not looking at a lot of power consumption on a freewheeling armature if the field is disconnected, just bearing and drive gear loss.
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If the motor is designed to reach optimum speeds e.g. 4000 rpm at 10 mph, what is going to happen to it at 60, 70, 80, 90, 100 mph? It would just put unnecessary wear and tear on motor and gearbox components.
I think I know an option that might be of interest. I'm getting a Bafang mid drive kit for my bicycle. Whilst I'm not planning on modifying my car, I know one of these has a freewheel built in and plenty of torque as it is driving the pedals so it should be able to turn wheels on a heavy car fine. All you'd need is a chain and sprocket then, although it would be preferrable to have the freewheel sprocket on the back wheel to stop any problems associated with a chain at high speed. It would be ideal to have the motor direct drive from the centre of the wheel though I am not sure how this would be done with existing brake gear in the way.
What I would be interested in is a custom sprocket that bolts on behind the wheel, contains an over run clutch and allows clearance for a chain without hitting the tire or side of the car. This seems like the most easy on, easy off setup without making permanent modifications to the car.
With 1000 watt motor at low speed I doubt torque vectoring would be a problem as the motor would likely only be used below 15 mph (about the same speed range as two people pushing my car from behind). It's been working fine on every power wheels vehicle so far. It's not designed to be a hybrid, more to use when going so slowly that the "basal metabolic rate" of the main engine is wasting fuel, and it would be more efficient to cut a hole in the floor and "Fred Flinstone" it. Though a motor on each wheel could add power.
For a go kart "differential" I would just use an engine driving a back axle and have each wheel be able to free wheel faster than the axle so that when it turns right only the right back wheel is powered and the left over runs and vice versa. Also if one wheel was off the ground or on slippery surface, the wheel on solid ground would do the work (unlike the situation you see in some cars - likely every FWD car I've ever driven - where the wheel on the snow slips and the wheel on the dry tarmac doesn't help it out.)