New motor that does away the old internal combustion engine

@FluffyMcDeath

Thanks sir! Much better said and it jives with what I said. This may be good for charging a battery but direct drive of a vehicle... Not so much.
 
faethor said:
@FluffyMcDeath
This may be good for charging a battery but direct drive of a vehicle... Not so much.
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Direct drive by internal combustion engine - in a literal sense - of a vehicle is almost never done. The power curve of an internal combustion engine is generally so narrow that all practical vehicles make use of a gear train to convert the engines rotation into wheel rotation of appropriate speed.

Metalman mentioned the diesel-electric used in railway engines. The reason why they use a diesel engine driving a generator which drives an electric motor is a practical consideration of matching the engine rotation to the requirements of the wheels. A large deisel puts out prodigious power but over a very narrow range of RPM. The wheels need to turn over a much greater range of RPM to take the train from standing to maybe up to 60 mph or more. The demands that this would place on a gear train generally make it impractical (too heavy, too complicated, too expensive, too inefficient). The electric motor can produce high torque over a wide range of RPM so the generator/motor combination is simply a replacement for the gears that would be needed. The situation is similar with gas turbines and this wave motor. The mismatch between engine RPM and torque and that required at the wheels could be accommodated by a suitable gear train but the requirements make a mechanical solution grossly complicated (and hence expensive). There are also losses at every engagement transferring energy from one cog to another and a complicated gear train can chew up a considerable amount of the available energy. Where there are big mismatches between input and output then an electrical intermediate ends up being cheaper, simpler AND more efficient.

Consider the gear system that would be required to take the rotation of the turbine shaft at the generator station and couple it appropriately to your vacuum clean AND your electric toothbrush. It's more or less the same thing. Turning the mechanical power into electricity first makes matching at the other end incredibly simple.
 
faethor said:
This solves the torque problem of the engine since a electric motor will supply full torque at 0 RPM.
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I don't see this in the article?

Certainly a confusing statement as torque is the force required to Rotate an object around an axis. The Per Minute measure is the speed at which it can move. If it's at 0 RPM there is no rotation and therefore no torque. Do you mean it can apply full torque immediately from standstill?
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Electric motors can be capable of delivering "constant" torque. A better way to think of it is as a flat torque curve (or no curve at all). I can't explain why that is, but I've read it enough times. I think it has something to do with the fact that torque in a motor is dependent on the amount of current you put through it. If torque is Force multiplied by distance, applying constant current would exert a constant amount of force, would it not? And since the distance here isn't the distance traveled but really the radius, torque should be constant. Note, that you can have torque at zero RPM because torque != work. You can apply tons of torque on a rusted bolt, just because it doesn't turn doesn't mean you applied zero torque. However, if it doesn't ever turn, then you performed zero work (which is why mechanics get paid by the hour :lol:).

As for gas engines, thermal dynamics limits the amount of force generated by those little explosions at any given RPM. Gas engines are tuned to a certain RPM so efficiencies come into play, so force varies and as such, so does torque.
 
Glaucus said:
"constant" torque. A better way to think of it is as a flat torque curve (or no curve at all).
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Your being confused by a special type ac electric motor design, with multiple windings

for a single winding, variable speed, dc motor, there are specified 2 numbers:

t(stall) = stall torque , torque is a maximum, but the shaft is not rotating.
angular velocity (no load) = the maximum output speed of the motor, no load, no torque

draw a straight line between the the two points,
torque = y axis, angular velocity = x-axis

the torque at any speed becomes

t(motor)= t(stall)- [angular velocity * t(stall)/angular velocity (no load)]

once the motor starts to spin it generates a "back emf" , the faster it spins the more emf is generated, until it reaches maximum speed & torque = 0

how specific DC motors respond to load changes depends on the specific arrangement of the windings.

Series wound dc motors are widely used as traction motors. A series wound motor has a low-resistance field winding connected in series with the armature. It responds to increased load by slowing down and this reduces the armature current and minimizes the risk of overheating.

Locomotives now use AC induction motors supplied pulsed power through solid state inverters
 
Direct drive by internal combustion engine - in a literal sense - of a vehicle is almost never done. The power curve of an internal combustion engine is generally so narrow that all practical vehicles make use of a gear train to convert the engines rotation into wheel rotation of appropriate speed.
Click to expand...

I'll go ahead and pick a nit and call ya on this paragraph. An internal combustion engine has one of the widest power curves of anything short of a electric motor. That is part of why internal combustion has been so popular for so long. It's a very easy engine to adapt to many applications.

And lots of vehicles still use the internal combustion engine with a single gear ratio. For starters, almost all boats under 50 feet run a standard internal combustion engine (or multiple engines) with a single fixed gear ratio, connected straight to the propeller. Many very light vehicles like scooters, go-karts, and Jet Skis run a single gear/clutch as well.

But going toward the future... I agree that series hybrid is the way to get more efficiency, by far. Electric is a very good way to drive wheels, and something like this wave engine is perfect for making electricity. The end result will be quite efficient.
 
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