Two Motors = Twice As Far????

The Prius does have two motors and the ICE, but MG1 is usually used as a generator, while MG2 is the motor doing most of the pushing the car down the road. They are not frequently used interchangeably.

Motors do not wear out very often, but they should reduce the wear on the ICE, both because it runs less, and because it gets help when it does run, reducing peak loads.

I find it even more interesting that the Prius has 4 Braking systems

1. Parking brakes, uses only the friction brakes on the rear wheels, while you are stopped.

2. Regenerative Brakes, uses MG1 when you are coasting, or MG2 when you are braking moderately above 7 MPH, using the front wheels.

3. B Mode, uses the ICE as a air pump, to reduce speed without storing energy, using the front wheels, for long downhill slopes.

4. Friction Brakes, using all 4 wheels, during panic stops and below 7 MPH.

Prius brakes are known to last a long time compared to 'normal' cars.

 

While the ICE does run less than in standard cars, it certainly starts and shuts off far more than most internal combustion engines in standard vehicles and as far as I understand, that results in the most wear and tear.

I would think it is a wash. Almost all modern engines are really reliable and last far longer than we are willing to use them if properly maintained.

 

I believe the OP is using the term "motors" in a very generic way, and is considering the ICE a motor. For clarification, a Prius has two electric motor-generators (MG1 & MG2) and one gasoline internal combustion engine (ICE).

As to the OP's original question: yes, the ICE on a Prius lives an easy life and should provide a very long service life. The starting cycle for the Prius ICE, while more frequent, is also much easier on the ICE than a traditional starter motor.

As also pointed out, most modern ICEs run for a very large number of miles.

Tom

 

Toyota has done it's best to minimize that wear and tear.

In a 'normal' car, the starter motor spins the engine with all it's might, while the Ignition is on, sooner or later the engine fires up. The owner may put it under load immediately, before he has good oil pressure.

In a Prius, MG1 spins the Engine THEN the ignition come on, so the ICE has oil pressure before there is any load. Early in the warm up period, MG2 is used a lot compared to the ICE, so it is protected from over zealous owners. We notice that as plummeting battery levels after startup, if we try to be 'zippy'.

The relatively small size of normal car batteries does not allow the luxury of spinning the engine before powering the ignition. Nor is there an alternative power source for the computers to favor while the engine warms up.

 

Even if two motors get you twice as far, it may not. Because if the motors gets you twice as far, as an engineer, you try to built is lighter to save gas.

They made the hood aluminum to save 20 pounds. So if the engine/electric motor combination gets you say 400,000 miles, any good engineer will start shaving weight off of it back to 200,000 miles to save gas.

If the ICE only runs 50% of the time, it does not have to be so tough. The water pump could be smaller because it is used only 50% of the time or a regular water pump. The walls can be thinner because it seldom will get hot enough to warp.

So it all end up being about the same in terms of longevity. It is not in the manufacturer's best interest to sell a heavy car that last twice as long. You want to sell a light, high mileage car with bragging rights. This is our throwaway society working for you. Any engineer that overdesigns a product and make it last longer than what the first owner wants to keep it is losing money for the car manufacturer.

 

The 2004 - 2009 engine block is shared with the Yaris.
Toyota NZ engine - Wikipedia, the free encyclopedia

The 2010 engine block is shared with the Matrix.
Toyota ZR engine - Wikipedia, the free encyclopedia

Because the conventional engine block IS a full time part, we can know Toyota did not scrimp on the bottom end of the engine. The heads/valvetrain are unique, so it could happen there, as well as bolt on accessories.

 

I am surprised. Maybe it is cheaper to share parts among car lines. For example, the brakes apparently last 100,000 miles. Why use tougher parts than necessary? It increase weight and decrease efficiency. Why carry 100,000 miles worth of brake pads when you roll off the showroom. A 55 mpg EPA average is much more impressive (assuming you trim a number of things, not just pads).

If you can cut a few pounds off the engine (sprung weight), you can use smaller springs, smaller shocks, less load on the tires, so the total saving in weight can be considerable.

 

Because when you need to stop the car, you need good brakes! Slimmed down brakes could overheat faster leading to brake fade more often then heavier ones and lawsuits.

 

There was an interesting article on "Quattroruote" (Italian most important car magazine) about a guy who travelled 491,348 kms (305,309 miles) in 80 months with its second gen Prius and sustained the following maintenance costs:

7,080 EUR (for 31 times regular maintenance)
8,003 EUR (for extra maintenance)

Battery change occurred at 471,486 kms (292,949 miles)
Breaking pads were changed every 190,000 kms (118,060 miles)
Tyres were changed every 85,000 kms (52,816 miles)
Distribution chain was changed at 245,000 kms (152,236 miles) (as a precaution, wasn't really necessary)
Catalytic converter was changed at 467,000 kms (290,180 miles)
Cylinder head gasket was changed at 450.000 kms (279,617 miles)

All in all he was problem-free until he reached 400,000 kms (248,548 miles).

 

Lighter brakes are not necessarily worse. They sell carbon fiber brakes and rotors. I think it is better for the environment if the car was lighter and burn less gas. Also, by the time you reach the end of life, the brakes would have been slimed down by wearing out. The car is not significantly more dangerous. Otherwise, why do people change brake pads at 100,000 and not at 50,000?

I do see your point. Maybe the engine is already as slim as it can be.

 

Yes all the common spare parts have to be kept at every Toyota dealership worldwide so there is a strong incentive to reuse parts as often as possible. (You know you are cranky when your dealership claims they are waiting on parts to repair your car, so is the owner of the dealership, he wants paid. He has to trade off delayed payment versus inventory costs. Parts with multiple applications make him happy, and incidentally, you too.)

Somewhat less commonly used parts are kept at regional distributors, and need expedited delivery. This makes it more expensive to use unique parts. Toyota not only wants to sell you a car that is cheap to make, they want to sell you a car that is cheap to service in their dealerships.

Rare parts the dealer may need to go back to Japan to find. No one is happy.

(Can you tell I once wrote portions of the dealer to distributor parts ordering, vehicle locator, warranty claims software for every Honda dealer in North America? The dealers loved finding extra parts at another dealerships here, (new old stock) so they did not have to order parts from Japan while your car was tying up one of their service bays)

 

I like to describe the Prius as a gasoline-powered car with a very clever transmission. The two motors description isn't really true because the electric components only serve to improve the way energy flows between the engine and the wheels. Ultimately the ICE does all of the work.