Hydraulic Hybrids- The next generation of cars?

[AeroModder]

High-Pressure Hybrids: Fuel-Efficient Hydraulic Vehicles Come of Age: Scientific American

Thanks to hybrid hydraulics, there is something especially awesome in the power of the next generation of garbage and delivery trucks that will soon be rolling through your neighborhood. Although they may still look like big, bulky trucks, inside they boast hydraulic power-train systems that are significantly more energy and fuel efficient than similar conventional or gasoline-electric hybrid vehicles. If hybrid hydraulics prove their mettle for more industrial uses, cars may not be far behind.

Could this be the system that ends our dependence on oil? With the smaller diesel engines, they could all be designed to run on biodiesel.

[user removed]

US patent # 7677208.

Get the wheel to wheel regenerative efficiency to 85%. It was 78% in 2006.

Direct engine to wheel at 90%.

regards
Mech

[jamesqf]

I don't think hydraulic hybrids work all that well for cars. If I understand correctly, they recapture energy efficiently and without the heating & charge/discharge rate issues of electric hybrids, so they shine in the stop-and-go cycle typical of garbage & delivery trucks, but don't have that much energy storage. Most cars aren't used in that kind of driving cycle. The electric hybrid as bridge to PHEV can fairly easily be increased to 30 miles or more of all-electric driving.

[Phantom]

I think that a smaller hydraulic hybrid system in a car could help. Mostly use it as a mild hybrid use it to remove the starter for quick starts at lights so you can start moving when the engine is starting. It would help with city driving that is stop and go and could recharge if needed at anytime the car is stopping. With a smaller system it would be likely that it would reach full capacity when there is still time to "charge" it so a secondary valve could be added to bleed the pressure off and power accessories. It would send pressure to what would essentially be half a turbo with a freewheeling pulley on the other side.

[puddleglum]

I do believe that a hyd. hybrid car is a fascinating idea, and with modern advances, has a lot of potential. But, this is not a new idea and for whatever reason, no one has managed to actually get one into production. I'm not sure if it is because the design is impractical for an automobile or there have been major design flaws in every design (possible but it seems unlikely), or is it because the people with a sound design don't have the capital and business expertise to make it happen. That's a debate I don't want to enter.
I found this article in an old Mechanics Illustrated that I thought some of you might find interesting, if you like nostalgia. It fits right in with the title of this thread.

[GreenHornet]

I know I know this is an old thread but I like the oldie but goodies

Why create a new thread when we can build upon this one. Up to this point I do not know much about these systems to be honest but I do find them quite fascinating and practical for where we are today. The best part about it is this is not a new technology its a mature technology that is used in all types of applications.

From little research I did yesterday on the subject I found that there is basically 2 setups like electric hybrids. You have your parallel and your series setups. The series setups utilize an extra pump motor to eliminate the transmission, driveline, and rear differential to propel the vehicle. The ICE is used only to pressurize the system not for propulsion. In the parallel setup you still retain the ICE driveline and the ability to use the ICE for propulsion. The parallel system is used basically to recapture kinetic energy while braking.

With today's modern electronic control and monitoring the hydraulic system is said to be able to recapture nearly 80% of the braking force of a vehicle. To me this is a very big number and one that has to be investigated further for its merits.

Having the ability to recapture 80% of braking force opens the door to take full advantage of coasting, pulse and glide, as well as start stop no idle engine technology. One of the biggest drains on the ICE during urban driving is idling while stopped and during initial acceleration. If you have the ability to eliminate these 2 energy sappers you have the ability to greatly improve fuel economy as well as reduce pollution

Some other major advantages I see right off the bat compared to electrics is no costly battery replacements, No BMS, No inverters, Its lighter more compact and more efficient, and lastly its cheaper!

So I am going to ask this question with all these advantages why are we not spending more time and resources perfecting this hybrid option?

GH

[user removed]

Sorry for the delayed response Green Hornet, I got your PM. I will post a reply here for others to read if they wish. If you want to communicate outside of the forum I will PM you my email address and we can go from there.

I have been trying to get a working version of the previously patented design built, but so far have no succeeded. It's one of those things that has to be done right and within very close tolerances or the benefits will be lost.

In 2006 Mr Kargul, from the linked article in the first post on this thread, basically stated that the cornerstone of the hydraulic hybrid system was the pump-motor design. AT that time the current state of the art technology was the bent axis pump. Which suffers significant efficiency losses at higher speeds. At low speeds it is in the mid 90s +, but at speeds of 2k RPM and higher that efficiency drops off to 75% which is unacceptable. The UPS vehicles used a bent axis pump running at prop shaft speed which is 3 or more times wheel speed so higher speed efficiency suffered. Igno Valentin as well as subsequent hydraulic hybrid designs addressed some of that efficiency loss by using in wheel drives, with various means of control of pressure and volume provided to the fixed displacement in wheel drives. This configuration still suffers from volume flow inefficiencies since the same amount of fluid passes through the drive ireespective of the load. The volume is directly proportional to the RPM of the in wheel drive.

The drive I patented resolves those issues by using a very ancient technology as it basis, the WW1 Rotary aircraft engine, but with several significant and crucial improvements, enough improvements to warrant a new patent on the design, a very difficult threshold to achieve.

The illustrations in the paten do a much better job of explaining how this works than I could in any thread here, but the bottom line is the drive is variable displacement, reversible, and works as foreward, neutral and reverse, using a single high pressure circuit for the fluid.

I'll continue in the next post.

[user removed]

With this design you can apply exactly the same amount of power at each wheel independently of the other wheels. Each wheel is it's own powertrain independent of the others. You can got to the neutral stroke position on any individual wheel or any combination of wheels for the purpose of traction control or antilock braking by adjusting the stroke position of each wheel.
Current traction control systems use brake friction which is supremely wasteful. My system would not waste any energy to control traction or braking, just vary the stroke position based on each wheels individual needs.
What is really misunderstood about a truly high efficiency hydraulic hybrid, despite my repeated attempts to explain it here, is when you reach a level of system overall efficiency you can use pulse and glide tactics, WITHOUT SPEED VARIATION, at only peak BSFC.
While P&G is vastly more efficienct than normal driving, the peak speed obtained incurs exponentially higher aero drag. Constant speed P&G with my system eliminates this significant loss.
Another sadly misunderstood fact is that a hydraulic hybrid cares not where it gets its stored energy power from. Be it electric, diesel, gas IC, steam, hydroelectric, solar panels, or friggin windmills and sails, the hydraulic system applies that stored energy more efficiently and recovers energy more efficiently that ANY alternative, in some cases magnitudes greater efficiency. An example is the 2006 EPA graphs comparing electric regeneration to hydraulic, with electric at 33% and hydraulic at 75%, not even close.
I knew this ten years ago and fought a war with idiots at the Patent Office to get my idea recognized. Now I find the war has just begun. so I am building a vehicle, then I will build a prtotype to demonstrate my design in a system that takes advantage of the unique characteristics of the design.
If you (Green Hornet) want to use my design in your vehicle, I would gladly provide you with a license to produce a functional example, but I think it would be costly (the first one always is), and it could be a disappointment, but after the year long Va Tech investigation with a postive judgement I think it will work and I will build it myself if I have to.
I have written many threads on this forum and others about my design and found the effort to be rather counterproductive. If you read the responses in the original linked article you will see an almost overwhelming ignorance of the most simple facts about hydraulic design and systems. After 10 years I just don't feel like spending the time trying to educate people without compensation.

regards
Mech

[cRiPpLe_rOoStEr]

I can bet the average country boy who was raised messing with tractors and their hydraulic PTOs would feel more comfortable dealing with a hydraulic-hybrid system than with an electric-hybrid.