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Discussion Starter · #1 ·
How does the engine turn on when I don't here a starter motor working
alanlpa :?
 

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Because there is no "starter" motor in the Prius. The gasoline engine is spun via the same electric motor used to propel you at slow speeds.

From my understanding, the internal combustion engine (ICE) is spun up to around 1,000 rpm before gasoline is injected into the cylinders (most starter motors only bring the engine up to around 150 RPM).
 

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Discussion Starter · #3 ·
when stopped??

The engine comes on even when the car is not moving, is the electric engine always turning??
 

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No, the electric motor only turns when it needs to. Either to move the car, or to start the ICE (you'll see that acronym a lot on here. It means "Internal Combustion Engine", the gas-burning part.)

The way the Prius' transmission works, the ICE, one of the two electric motors, and the wheels are pretty much always connected. So if you spin one, at least one of the other two has to be spinning, too. If the car is stopped, then either both the ICE *AND* the electric motor are stopped, or both are running. So when you first turn on the Prius, after a few seconds, it needs to start the ICE warm-up cycle. It spins the electric motor to spin the ICE (same basic idea as a conventional car's starter motor,) but once the ICE is spinning on its own, the ICE spins the electric motor, which generates electricity to recharge the battery. So it's a 'two-for-one', in that warming up the ICE also recharges the battery.

Once the ICE is warmed up, (assuming you haven't started moving yet,) it shuts down, which also stops the electric motor, so your battery doesn't get charged any more.

Once you start moving, the car decides how to apply power. Either from the electric motor only, leaving the ICE stationary (again, starting one of the three items turning means that at least one more has to, rather obvious when trying to apply power.) Or we can run off both ICE and electric, adding together their torques to drive the wheels. Finally, when we're up to a reasonable speed, it may choose to use only the ICE. When only the ICE is powering the car, we have one of two situations: either all of the ICE's power is used to turn the wheels, in which case the electric motor is stationary; or the ICE may be actually producing more power than is needed to drive the wheels, in which case it also spins the electric motor, charging the battery.

As long winded as this is, it's also an over-simplification, since there is a second electric motor in there that operates differently from the one I was talking about above. (For example, it may have the ICE spin one motor, creating electricity, that then gets sent to the second electric motor to help drive the car. It may seem silly, but it's great for converting horsepower into torque more efficiently than the gas engine alone could accomplish.)
 

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Discussion Starter · #5 ·
Thanks

Now I understant a little more about this technological marvel I just got
Thanks again
Alanlpa
 

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ehurtley said:
(For example, it may have the ICE spin one motor, creating electricity, that then gets sent to the second electric motor to help drive the car. It may seem silly, but it's great for converting horsepower into torque more efficiently than the gas engine alone could accomplish.)
The example seems less silly when you realize that this is how railroad locomotives have operated since the 1940's. "Diesel" engines are really "Diesel-electric" The diesel engine powers a generator that drives traction motors by the wheel. This allows a relatively small engine to pull a large train.

Digression:

The largest commonly used locomotives are 6000 horsepower monsters, A coal train can weigh up to 13,650 tons. Even if you put six of those monster locomotives on that train, you have a power to weight ration of 1/758 (HP/LB). Our prii have 140 hp pushing 1.5 tons, or 1/21 (HP/LB).
 

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Prius...

Check out http://home.earthlink.net/~graham1/MyTo ... Frames.htm

then click on the far left "Understanding Your Prius". This is a VERY well done site that really makes you appreciate what's happening while you zip along in your tech-marvel car! Simple, yet effective, yet complex.
Anyways, take the time to 'know' how your Prius works, then tell others. I've really made friends explaining even the major components and how they work. It fascinates people...and it still fascinates me. Love my Prius!
 

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The example seems less silly when you realize that this is how railroad locomotives have operated since the 1940's
Not really. Some locomotives are actually diesel-electric hybrids, but they are of the "series" type, i.e. there is no mechanical connection between the engine and the wheels. The engine only acts as a power plant producing electricity for the motors. The Prius does have a direct mechanical connection between engine and front wheels, it's not a "series" hybrid. Er... it's not a "parallel" hybrid either, by the way : Toyota calls it a "series/parallel" hybrid. :? Kind of a strange type of vehicle indeed...
 

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The link in Finman's post gives an outstanding, detailed description.

There are two MG's. MG2 most often functions to propel the car (alone or along with the ICE) and to provide regenerative braking. MG1 is the starter motor and also a generator to turn part of the ICE's power to electricity, which can recharge the battery or help power MG2.

MG2 is connected to the wheels via a fixed-reduction gear. MG1 is not. Therefore MG1 can start the ICE whether the car is moving or not. (Both MG's can also act in unexpected, arcane ways.)

All this stuff is connected, without any clutches, via the power-split device, wonderfully diagrammed on Graham's site.
 
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