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In their 2006 documents the EPA combined with Ford, Eaton, the University of Michigan, as well as others stated that an 80% improvement could be accomplished by improvements in the power train that used capacitive storage of regeneration energy as well as separating the engine's function from the act of driving the vehicle itself.
Combine that with engine efficiency improvements that are a reality today, 5 years later, when you separate the engine from directly driving the wheels, and you have a combination of efficiency improvements that was predicted to improve economy by 120%.
Since 2006 we have seen improvements in manufactured cars that incorporate some of these ideas. Direct injection, automated manual transmissions, fuel injection that actually occurs during the combustion stroke, all steps in the right direction but there is much more room for improvement.
The key ingredient that has yet to be incorporated is capacitive energy storage at extremely high efficiencies.
All of these things point to a direction in development that could best be defined by the EPA's call for a "clean sheet of paper" design of a replacement for the bent axis variable displacement hydraulic pump-drive they used in their 3800 pound demo vehicle that averaged 80 MPG using a 1.9 liter diesel engine.
It's all about load levelling and short term averaging of the highly variable load requirements of normal vehicle operation. In essence to incorporate the proven technology of pulse and glide into the vehicle's power train itself. Bottom line is the self hypermiling car, a vehicle that can maintain a given speed while the engine cycles on and off, only consuming fuel and creating energy at it's highest level of efficiency.
My clean sheet of paper design was conceived with all of this knowledge as the cornerstone of its design and development. It was also a principle factor that the design would be simple as well as inexpensive to produce when mass production occurred, while retaining reliability that surpassed anything on the market today. This is a crucial component, you have to build it at a competitive price, it has to last a very long time, and it has to be very low maintenance, and when maintenance is required it has to be simple to fix.
I am not aware of any design that can compete with a IVT hydraulic drive when you compare all of the relevant factors, cost, efficiency, and reliability. Affordable, reliable, and efficient.
In fact, you may not even consider it a real hybrid, since by eliminating the accumulator from the circuit it simply becomes a direct hydraulic drive that has no limit for final drive ratio. It could go from 1000 RPM of the engine to 1 RPM of the wheel, to 1 RPM of the engine to 1000 of the wheel. No drive can come close to that range of ratios.
The accumulator has the responsibility of capacitive storage of energy. This means you do not have to sacrifice engine efficiency in any direct drive. It allows the engine to work at it best efficiency regardless of the power train demand requirements. All you need to have is an engine with sufficient power to cover all situations where sustained demand is much higher than the normal demand. You have to climb the mountains. You have to recover a reasonable amount of deceleration energy. You have to recover almost all of the energy in 20 revolutions of the wheels in a panic stop.
You have to do all of this at an efficiency level of 80% or more.
This may be perceived as a thread hijack by some. I feel it is an opportunity for all to understand that the last number of posts have touched on a subject where there actually is a better solution that the ones discussed. That is my opinion and it has some credibility from independent investigation by qualified professionals.
Thanks for your time
Mech
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