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Old 03-19-2010, 08:03 AM   #11 (permalink)
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A 5.5 HP Honda pressure washer produces 2.2 gallons at 2700 PSI.

With an accumulator you could store energy and launch a 4000 pound car to 70 MPH.


It takes 20 revolutions of the wheels to go 0-60 in 5 seconds in a car the size of a Corolla. The same number of revolutions to stop the car in just over 120 Feet.

At 30% (typical electric regen) you get 3.3 revolutions out of 20 back. At 80% you get 16.
Hydraulic Hybrids were at 78% 4 years ago, according to sources at Next Energy when I went there in 2006.

Cost becomes an advantage when you eliminate the hundreds of parts that are used to transfer power to the wheels in a conventional power train. Transmission, clutch, differential, axles, brakes, all gone.

Cost per wheel unit (manufacturing cost) would be about $100. Like a smart bomb, the axle, hub and bearings are already there.

An accumulator is basically a tank with a balloon inside the tank. Cycle life expectancy is measured in the tens of thousands, and you rebuild it by replacing the balloon. Very mature technology.

Take a Pontiac Solstice, which has a hydro formed tubular frame and used the frame as the accumulator. Replace the conventional power train with 4 in wheel drives. Put a .9 liter electric supercharged engine in it and you have 0-60 in 4 seconds and 100 MPG with decent aero and low rolling resistance tires.

About 2000 pounds curb weight.

The limiting factor for acceleration is the max displacement of the in wheel drives and the tires traction. Reverse engineer the system to reach the limits of traction under ideal circumstances and use wheel slip indicators to reduce displacement for traction control and ABS.

Virginia Tech calculated the power of my design at 35 HP and 380 pounds feet of torque.

Per wheel.

Much like the electric motor that produces high torque relative to the horsepower.

Even in an electric configuration, consider this point. You do not need to control the current flow to the motor, since it is either charging the accumulator or not running.

Pulse and glide has been proven to be effective even in electric cars. This system makes P&G and integral part of the vehicle itself, while maintaining a constant speed, even while employing a P&G strategy.

If you use an IC engine you need no throttle control or fuel delivery control, just on or off accumulator charging.

Now consider the sum total of parts you no longer need to offset the cost of the in wheel drives and the accumulator. The true cost would be offset by the brake components and the power train and induction system components no longer needed.

Overall you should see a 25% reduction in total parts count per vehicle, and a 15% reduction in per vehicle manufacturing cost.

I can build a system that would work on a bicycle, motorcycle, car, truck, train, ships, or even airplanes. Anything with wheels can be capable or regeneration.

Start-stop is simply reversing the flow of pressure from accumulator to engine, with only the controls necessary for reversing the flow.


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Old 03-19-2010, 08:07 AM   #12 (permalink)
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Originally Posted by puddleglum View Post
the new design of hydrstatic motor that Innas shows might actually make a hydraulic drive feasible if they can make it inexpensively enough. high weight, low efficiency and high cost have been three strikes against hydraulic drive. Maybe they've overcome two of them anyway.
The same statement applies to all electric vehicles as well as IC electric hybrids equally, at least that's my opinion.

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Old 03-19-2010, 08:40 AM   #13 (permalink)
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Originally Posted by Old Mechanic View Post
At 30% (typical electric regen) you get 3.3 revolutions out of 20 back. At 80% you get 16.
Hydraulic Hybrids were at 78% 4 years ago, according to sources at Next Energy when I went there in 2006.
I hold electric regen round-trip efficiency to be about 70%, excluding losses in the tires. Page 33 of this document shows motor*inverter efficiency (which needs to be squared for round-trip) was measured at >0.9 across the most usable part of its range of operating speeds. Losses in the battery are very small.
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Old 03-19-2010, 09:54 AM   #14 (permalink)
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I looked through the document you provided Robert. While the average of motor and inverter efficiencies looks like it is about 70%, that does not cover the wheel to wheel efficiencies.

The example you provided (Honda Accord) also has a CVT transmission which has its own losses, as well as the battery which also has losses. Manuals have losses as well in both directions (application and recovery).

Consider the Insight you and I drive, which can only recover half of the energy it can generate electrically. Also consider that it is generally accepted that best efficiency is achieved by minimizing the battery use in the Insight.

That puts the Insight at 50% recovery, with additional losses in reapplication that further reduce the efficiency to close to the percentage I provided.

That's wheel to wheel. including all of the cumulative losses. While we can debate the percentage of cumulative losses, you can not debate the fact that batteries will not accept energy input at the same rate as they will output the same level of energy.

That's a non issue with hydraulics.

In your provided example, the energy pathway is wheel, to axle, to differential, to transmission, to motor, to controller, to cables, to battery. Each component compounds to totality of cumulative losses as you know. The same pathway is duplicated in reapplying the power which effective doubles the cumulative losses. In any process where the steps in energy conversion are many, even the smallest losses are compounded.

Another disadvantage of the Accord configuration is the motor can only spin with the engine, which is solvable by placing another clutch between the IMA and engine.

Electric motor efficiencies are best in a certain range of speed, while in-wheel drives are most efficient at the lower speeds of the wheels. In the referenced photos the bent axis pump is spinning at the same speed as the propeller shaft, which kills its efficiency. In- wheel drives at all 4 wheels suffer from no such issue and can recover energy to the last revolution of the wheel itself and at efficiencies that are their highest when fluid flow rates are lowest.

Compare the cycle life expectancy of any battery to an accumulator. There is no comparison and rebuilding an accumulator is a simple process that is very inexpensive compared to rebuilding or replacing a battery.

The cumulative losses of electric configurations do not allow P&G operation of the system.

The INNAS link clearly states that engine to accumulator P&G is an essential part of the operational strategy.

The bent axis pump used in the comparison (photos provided) is not designed specifically for the application. The rest of the components are also off the shelf.

My design was from the very beginning conceived for the specific purpose of replacing the power train in vehicles, at a cost that makes an inexpensive basic vehicle possible at $10K newly produced. That amount wont cover the cost of the battery in the Nissan Leaf, with a 100 mile range.

Even in the Leaf a launch assist rear axle with my in-wheel drives and an accumulator of two gallons capacity would extend the range by possible 50%.

That's a prediction I can not back up with concrete data, but I must emphasize this point. If you can P&G any vehicle in its current configuration, you can improve its mileage by incorporating P&G into the vehicle itself.

Some may consider that an over simplistic statement, but I maintain it as a fact that seems to be largely misunderstood today.

I hope our conscientious debate contributes to the knowledge base of everyone who reads this thread, my friend.

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Old 03-19-2010, 02:02 PM   #15 (permalink)
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The problem is that while hydraulic has a good cycle efficiency - that is, you get back a lot of the braking energy - there's not that much stored energy. The storage tends to be heavy, too, because it's stored by compressing gas to high pressure. That's why you see the hydraulic hybrids used in UPS delivery vans, garbage trucks, and other places with a frequent start-stop cycle.

For a car to be practical (around here, anyway), you need a powerplant plus storage that can power it up 5000 vertical feet of 7% grade at highway speed.
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Old 03-19-2010, 02:44 PM   #16 (permalink)
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Very true James, but how much of your range in a Nissan Leaf will you loose in the same climb.

5000 feet in a 3300 pound car is 6 HP seconds per foot of elevation, or 42 HP per second per 100 feet traveled on a 7% grade.

5000/7=714 seconds of 42 HP above what it takes for you to travel the same speed on level ground.

3600/714=12 minutes at 42 HP above the level ground demand.

Level ground sustained demand at that speed is probably 7 HP give or take.

Say 37 kilowatts sustained for 12 minutes, or 6.6 kwh of battery capacity just to make the grade in your example, assuming it is 7% consistently for 5000 vertical feet.

You would have travelled 71400 feet distance or 13.5 miles.

Now double your example, or even triple it.

How much battery do you need with a 30% usable reserve capacity, and how long will it last being subjected to that kind of discharge stress on a daily basis?

The example of sustained grade climbing applies to both vehicles. If I need only a 75 HP gas engine to make the same grade, that engine is running at its peak efficiency. In fact you can size the engine to make it operate at peak efficiency on that grade and it won't change the overall mileage of the vehicle. The larger the engine the less time it needs to maintain accumulator reserves, so the only penalty for a larger engine is the weight of the engine itself.

The UPS trucks gross weight is 26000 pounds based on its class size. We are talking about a car that weighs 2000-2200 pounds. The INNAS (linked in my first post) thread clearly states "no weight penalty".

The in-wheel drives weight the same as the brake components they replace (weight neutral).

The cross members that support the suspension could do double duty as the accumulators, so their additional weight would be negligible if any.

On the other hand you need a 400 pound battery pack, a fairly heavy motor, some form of transmission and power train and you still need brakes for when your speed is so low regeneration can not be effectively accomplished.

How bad is the wear on your brakes when you are going down the same grade beyond your regenerative capacity?

Please correct me if my math is seriously flawed.

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Old 03-20-2010, 01:09 PM   #17 (permalink)
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How do they come up with a mileage number like this -- if the car is just a sketch?
Sincerely, Neil

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Old 03-21-2010, 12:24 AM   #18 (permalink)
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Originally Posted by Old Mechanic View Post
The INNAS (linked in my first post) thread clearly states "no weight penalty".
Sure. It also says that it's got images of the car, when all I see are some sketches that any moderately competent artist could whip out in a few hours.

As for using the frame members as pressure storage vessels... Well, I'd want to see a real good engineering analysis of that. What happens when a member holding say 4000 psi is subject to road shocks? I don't know, but I think the stresses would add...
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Old 03-21-2010, 09:33 AM   #19 (permalink)
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Originally Posted by Christ View Post
With a hydraulic drive system, the fueled engine runs at it's most efficient RPM/load ALL THE TIME. Your car doesn't do that.
Any sort of hybrid is always going to be a trade-off between efficiency, emissions, engine wear, and performance like any other car. W/ a hydraulic hybrid based on a typical car, the engine would have to cycle on and off much more because the accumulator would have to be relatively small or w/ a smaller engine performance would be sub-par compared to a hybrid. If the accumulator is as large as a battery pack in terms of energy storage then the car would weigh a half ton more than a comparable hybrid and performance would suffer. It's all about trade-offs and HHs just don't offer the same characteristics that HEVs do and consumers want for whatever price.
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Old 03-23-2010, 10:57 PM   #20 (permalink)
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Maybe its watching a frame machine twist a full sized pickup frame like it was a plastic straw.

Or a 4 ton hand pumped hydraulic ram twist a truck frame 3 to 4 inches with the power of your arm.

Or a Kansas Jack ripping a uni body apart like a piece of paper.

Hydraulics is a very mature technology.

The pelton wheel hit 90% 120 years ago.

Even a water wheel easily topped 60%, 2000 years ago in Roman times.

An accumulator can get as close to 0 loss as you can get at 99% efficiency.

A 500 hp hydraulic motor is light enough to hold in one hand.

Designed to reach the maximum torque capability of the tire to road surface interface, you have the ability to provide 100% of the traction capability of every wheel on the vehicle, it you want to do a 1/4 mile as fast as any dragster on the planet.

Without any engine whatsoever.

The 5 states of vehicle operation.


With a 5 gallon accumulator weighing as much as one passenger you can accelerate a car to 60 MPH in 20 revolutions of the wheels, and stop it in the same distance and recover over 80 % of the energy, minus of course the aero and rolling resistance losses.

Your rate of acceleration and deceleration is not relevant to the efficiency of the energy recovery. Panic stops and full accelerations make no difference in the efficiency of the energy recovery.

The engine can be operated at only its maximum efficiency regardless of vehicle speed or rate of acceleration or deceleration.

Idling does not exist.

Acceleration is merely choosing the rate at which you choose, the energy requirements are not relevant to economy.

Coasting is truly coasting with no power train losses, no gears pumping fluid from the gear teeth, even more efficient than neutral in a manual transmission because many of the gears and differential gears are still pumping fluid away from the gear teeth, no u joints, CV axles, no spinning parts to use energy to accelerate and decelerate.

Deceleration is regeneration

Braking is regeneration

In both cases you are recovering energy at all 4 wheels up to their maximum traction capability, down to 0 wheel speed.

The free piston direct hydraulic engine pump had a theoretical efficiency of 58% ten years ago. Today they are approaching 50% and with super critical direct injection at 30k PSI you will see engines make 60% energy conversion efficiencies, if they haven't down so already in a lab.

Is 170 MPG possible?

At what speed?

Average speeds of the EPA city cycle are about 27 MPH. At those speeds 170 is possible if the whole vehicle system is optimized for efficiency.

At highway speeds where aerodynamics become the dominant energy drain the mileage would be closer to the 80-100 range, totally depending on aero and rolling resistance optimization.

This is possible right now. Valentin, INNAS, Lightning, and several other organizations are working very hard to get us there. A military HUMMER averaged 22 MPG with a hydraulic drive conversion.

Every developer admits the most important component is the drive motor, which needs to be incorporated within the wheel, so there are no necessary mechanical connections.

You want to use a battery and an electric motor to drive this platform?

It changes nothing, just a different power source that consumes a different form of energy.

This week I started receiving junk mail from companies soliciting me to represent my patent. Its been published and it will be issued. Hopefully by the end of this year the system will be in a bicycle. A human hydraulic hybrid, that is fairly lightweight and refutes every assumption that it has to weigh to much to be practical.

0-60 as fast as a sport bike, pulse a glide capable with no engine other than human power. Spend 30 minutes completely charging the accumulator and you have 3 times the available human power for 15 minutes at 50 MPH.

On a bike with no engine requiring no fuel or electricity.

If you don't want to spend 30 minutes on your exercise machine plug it in the wall and charge the accumulator.

Fully enclosed and all weather capable, the vehicle itself will weigh about 200 pounds total or even less. That makes it just over 400 pounds with me included.


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