Why don’t we have internal combustion/electric vehicles?
Most freight trains now have a diesel engine that turns a generator. The electricity generated by the generator is used to turn electric motors at the trains wheels. These trains are capable of hauling massive loads, yet achieving decent fuel economy. I understand that the diesels used are of an extremely high horsepower rating. But why can’t we apply the same tech. to autos?
There are very large off-highway dump trucks (Komatsu) that use this driveline.
Those diesels are not used for “extremely high horsepower” but “extremely high TORQUE”
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The main reason for diesel-electric, also a favored plant on ships, is that it allows for gear reduction and variable speed without huge reduction gears and/or a transmission. They would not produce a significant fuel savings in cars, and would cost more than an automotive transmission.
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Diesel-electric is actually a way to manage the mechanical issues of a rail locomotive. It is not as efficient in motion as a mechanical transmission, but there is no clutch wear when starting from a halt and there are no complex driveshafts to get power down from the engines to the pivoting wheel trucks.
Diesel-electric started as a system for switch engines, which start, stop and reverse all day. Later it was adopted for over-the-road locomotives because it was more reliable and cost a lot less money to keep running.
Passenger cars and even semi trucks don't have the same mechanical issues, so they get better efficiency with mechanical transmissions and still have good reliability. A modern automatic transmission is usually good for the life of the car without even changing its fluid, and mechanical transmissions are both cheaper and lighter than motor/generator systems.
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david M is correct.
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the electric transmission system is very simple, reliable and cheap because electric motors produce maximum torque from 0rpm
hence the Tesla only has about 6 moving parts in the transmission and can provide high rates of acceleration with no gear changes
also the Killacycle drag bike http://www.killacycle.com
the vapourware Chey Volt will use the diesel-electric principle - but given GMs past crushing of electric vehicles don't hold your breath for one.
The reasons we don't have internal combustion/electric vehicles are explored in the film "who killed the electric car" http://www.whokilledtheelectriccar.com
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http://www.evuk.co.uk
Weight and cost.
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part of the problem is packaging the system. finding room for a small internal combustion engine powered generator is not easy in the smaller cars that the automakers are building without giving up either passenger capacity or trunk capacity. the current hybrid design has the supplemental electric motor built into the transmission so it doesnt take up much room. with a larger car though, or even pick up trucks and larger vehicles, it can be made reasonably viable.
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I agree with “Common Sense”.
A diesel/electric locomotive/ship does not have the same weight/space issues that a car has.
For every “green” solution, you first have to overcome a few problems. Most of us that drive to work, only drive between 5 and 30 miles and a pure battery car would suit us fine. But we also take vacations, go camping, tow a boat, etc. and in doing so, we need a vehicle that allows us to do these things. You also have the cost issue to overcome. Why would anybody go out and buy a $25,000 - $35,000 pure electric car when you can get a 5 year old used car for a fraction of that cost? To keep prices low for a pure electric car, there would more than likely some sort of government subsidy, and in doing so, that would mean we all will pay for it.
We also have to realize that a locomotive or a ship operates much differently than a normal car does. Once a ship leaves port, it goes until it reaches its destination. A ship does not spend half its time in a traffic jam. Yes, a locomotive does stop every now and then, but for the most part it just keeps on going down the tracks until it reaches its destination.
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There are very large off-highway dump trucks (Komatsu) that use this driveline.
Those diesels are not used for “extremely high horsepower” but “extremely high TORQUE”
References :