I have a question about the Prius' hybrid system.

Massacure

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Thu May-26-05 05:52 PM
Original message

I have a question about the Prius' hybrid system.

How come the Prius was built to use its engine for driving?

Is it not easier to drive the vehicle forward using on the motor while charging batteries with an engine at a specific sweet spot? Are internal combustion engines more energy efficient in general than motors?

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phantom power

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Thu May-26-05 05:55 PM
Response to Original message

1. an electric motor is more efficient, however

Edited on Thu May-26-05 05:57 PM by phantom power

if you are running the engine, you incurr less energy loss if you use it's output directly, as opposed to running the engine, driving a generator, and using the output of the generator to run an electric motor.

Their system probably also allows for a smaller generator, which saves space and mass.

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benburch

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Thu May-26-05 06:04 PM
Response to Reply #1

3. Actually, it is a motor-generator.

And you are correct; Direct use of torque is most efficient. The system runs the motor at an efficient level, and cuts in generator load dynamically to control speed.

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rustydad

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Thu May-26-05 07:46 PM
Response to Reply #1

4. Hybrid

The use of a battery powered boost electric motor allows the car to have a much smaller IC engine. The ICE is used for cruising and is assisted on hills and acceleration by the electric motor. Also on braking the electric motor is run as a generator to help slow the car and charge the battery at the same time. It is a complex and expensive system and the upkeep on the battery may be problematic over time. If one was content with slow acceleration and restricted high speeds a light weight diesel powered car like the Lupo (VW) can get close to 100 mpg and cost far less than the hybid cars. A bike is even better. Bob, on a bike with a 1 hp motor

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NNadir

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Thu May-26-05 10:24 PM
Response to Reply #4

5. A bike is an oustanding machine.

It is non polluting, good for your health, extremely efficient and easily fueled. It gets you there fairly quickly, is easy to park and can even go off road. Maintenance is low, and it causes no pollution other than CO2 and a little grease. The fuel is obtained 100% for solar sources and no elaborate devices with poor working properties are needed to make the fuel. The fuel, and most of the materials used in producing it and handling it are all non-toxic.

Man, I miss the three or four years in LA where I didn't own a car. I was fit and strong and I had incredible stamina.

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rustydad

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Fri May-27-05 03:50 PM
Response to Reply #5

6. In all honesty

My bike is a hybrid. At a close encounter with age 65 and a commute to town distance of 25 miles and elevation change of 1500 feet I have a 10 # one horsepower engine on my mountain bike. Hills and acceleration from stop need leg power help to the engine. Cruising at 30mph is leg free. I have put about 4000 miles on the bike in a year and the legs and stamina have been improved although not to the level of serious riders of younger years. My gas savings have paid for the motor kit and then some. I average around 250 mpg and a fill up here in SoCal is 75 cents. Bob

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mike_c

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Thu May-26-05 06:03 PM
Response to Original message

2. there is ALWAYS conversion inefficiency and energy loss...

Edited on Thu May-26-05 06:03 PM by mike_c

...so in order to obtain X number of joules to move the car via electricity, you would have to burn X+Y joules of gasoline (this is over simplified of course, because there are actually multiple energy conversions involved in going from gasoline to the kinetic energy the generator, to the stored electrical energy). The basic answer is that the car can be run on LESS energy-- X in this example-- if it is powered dierectly by the engine.

The payoff for hybrids is to divert energy that is NOT needed to run the car but is produced by the engine anyway into battery storage, then to use that energy later to power the car on the electric motor.

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