Prius Engine Break

[trollbait]

This is found under second link I posted.
http://prius.ecrostech.com/original/PriusFrames.htm
Go there for the complete description, but here is part:

This is our clue to how the epicyclic gear allows the ICE spin rate to be adjusted like a CVT. For any given road speed, the computer figures out how fast the ring gear is spinning. From the power demand, it decides how fast it would like the ICE to spin. Then it just solves a simple equation to figure out how fast MG1 must spin. Then, it adjusts the power drawn off by MG1 to speed up or slow down the ICE until the desired condition is achieved. None of this affects the fact that 72% of the ICE torque is sent towards the wheels. The wheels can even be stationary and this torque is still applied. By allowing the ICE to drive the car from stationary in this way, we do away with the need for a clutch or torque converter, actually eliminating a wear-prone and bulky component of the transmission.

Elements of the Prius transmission may act, and fill the roll, of a clutch or torque converter, but there isn't a seperate, efficiency robbing, component doing the job.

[dkjones96]

Simple explanation:

The Prius uses an AC motor as its variable torque converter. The rotor is connected to the input shaft(the engine) and the stator is connected to the output shaft(to the power split device). They adjust the engine speed by adjusting the amount of slip in the AC motor.

Great idea but it can't be used on a normal car.

[JanGeo]

So it really acts like a clutch in that it provides an adjustable torque and slippage - my understanding of a torque converter is that it is capable of increasing the output torque to more than the input torque thus it really isn't a touque converter.

The Prius uses some very clever ways of coupling power to the wheels. They did a lot of tweeking in the control of the MG1 and MG2 to really get it to keep the battery charge within that narrow band of state of charge (SOC). This really explains why modification of the available energy used in the battery has been such a big problem with people trying to modify the car for (PEV) Plug in Electric Vehicle operation. What is desired is to allow greater discharge and charge of the traction battery beyond the 15% they limit it to so that greater electric distance can be obtained with the addition of a bigger traction battery. As you may know, the "OIL COMPANIES" have a patent on the use of NiMh batteries in propulsion and they limit the capacity to 10 amp hours or less. If Toyota could put a bigger battery in it and still keep it in the 15% SOC range they could still increase the electric drive range considerably.

Reading the description of the engine and how they control of pumping losses making the engine more efficient than other variations of the same engine is also a great read. By controlling the intake valve timing they regulate the intake charge volume without high vacuum causing increased pumping losses. The engine runs more efficiently at light to moderate power levels than the basic Echo engine design it was taken from.

[theholycow]

Originally Posted by JanGeo

As you may know, the "OIL COMPANIES" have a patent on the use of NiMh batteries in propulsion and they limit the capacity to 10 amp hours or less.

Interesting. I wasn't aware of that. Can you give me links about it? A quick googling turned up too much stuff and I didn't know exactly what I was looking for.

[trollbait]

Hooray for Wikipedia.
http://en.wikipedia.org/wiki/Cobasys
This is the entry on Cobasys, the current holder on large format NiMH
batteries. It should be a good starting point.

Here is a basic rundown:
GM and Ovonic Battery Company, whose parent company developed various NiMH patents, form a parntership. One of the products of this partnership is the NiMH battery that gives the EV1 a max range of 150 miles.

After the EV1 is crushed, Texaco/Chevron buys out GM's 60% share. They already own 20%. Eventually renaming it Cobasys.

Cobasys sues Panasonic and Toyota over the Prius battery. Putting the royalty and money issue aside, Cobasys gets a limit put on the size of the Prius battery pack.
Why do so if if being properly compensated as apatent holder is your main concern?


Other tidbits I saw in the google search; Daimler is sueing Cobasys over failure to supply batteries for their hybrids, and GM had to recall 9000 of their hybrid vehicles over leaky Cobasys batteries. It starts to enter conspiracy territory, but what company would with hold use of a patent that they could profit on?

[dkjones96]

Lithium Ion or Lithium Polymer are both MUCH better choices anyways!

Battery type...Capacity(Wh/Kg)...Cost(Wh/$)...Cycle Life...Charge/Discharge
NiMH................30-80.................2.75...........500-1000........66%
Lithium Ion........160....................2.8-5...........1200.............99.9%
Lithium Poly.......130-200..............2.8-5...........>1000...........99.8%

They're cheaper, higher capacity, last longer, and are much more efficient.

I believe they should be using lithium polymer. They have a very fast charge and discharge rate. I've messed a lot with lithium polymer and I've gotta say that I believe they are the fastest charging and discharging batteries I've ever had the pleasure of messing with. Why even bother with old battery technology?

All of those toys you charge up for 30 seconds and play with for 3 minutes are run by lithium polymer batteries. Those foam remote controlled planes can't fly with heavy NiMH batteries in um.

[JanGeo]

The problem with Lithium batteries is that they don't like to operate in the harsh car environment. Take any of those high energy lithium cells you play with and heat them up to say 150 degrees and then add a load to them and watch the fireworks. Second is the cost since just about no one makes them in the USA then they have to come from usually China . . . put a battery pack that is big enough in a car to power it and you can expect to pay $20,000 for the battery. I know because I bought a 2kwh pack and it cost me $1550 plus a few hundred more for battery management and a car is going to need at least 5 times that size just to go about 50-60 miles on electric power. Then you have to consider how much the battery ages even without use. Lithiums in laptops typically last 3 years or less before their capacity diminishes to almost nothing. Until the proven nano technology enhansement gets a little more popular and the energy density gets a little higher we will not see Lithium used in cars just yet.

For the complete story watch "Who Killed the Electric Car".

[trollbait]

In addition to the question of their performance and cost, there is also the question of whether there is enough lithium in the world to replace the auto fleet, and recycling. I've heard that only 20% of the lithium from a battery is recovered, while you get 100% of the nickle and lead.

The future is likely lithium, but that isn't a reason for why we can't be using NiMH now. There are EV RAV4s on the road now with the range to cover over 90% of their owners' automotive needs. That's with a 10 year old NiMH pack that doesn't have the very protective charge limits of a Prius pack. However, if one of those RAV4s were to need a new battery, they couldn't get one, because Cobasys isn't allowing the sale of the large size pack.

[dkjones96]

3 years and it's useless? Who told you that? I still get a good 2.5-3 hours out of my laptop and I've had it a year and the guy that owned it before me let it sit in a box dead for at least 5 because of a 'broken' screen.

[JanGeo]

Originally Posted by dkjones96

3 years and it's useless? Who told you that? I still get a good 2.5-3 hours out of my laptop and I've had it a year and the guy that owned it before me let it sit in a box dead for at least 5 because of a 'broken' screen.

Are you sure it has a lithium battery in it? As far as how I know I see it happen with all the laptops I sell and use. I keep my main laptop plugged in all the time and the battery monitor after about 5 years still says 2.5 hours remaining and in 10 minutes it shuts down without a warning . . . battery dead! Once in a while you may get a battery pack that was stored properly and will work for several years but that is extreemly rare. Best storage condition for lithium cells is 30-50% charged and 35 degree temperature.