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Old 01-11-2012, 11:55 PM   #31 (permalink)
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Accumulators reach efficiencies of 99%.
Hydraulic rams are very close to the same.

Green Car Congress: Innas and NOAX to Show Hydraulic Series Hybrid Drivetrain at Hannover Messe

Here is a similar system, but mine needs no transformers since the stroke on the in wheel drives is variable and reversible.

If you are really interested read the whole article and remember it was published 3 years ago. We're still waiting for the miracle battery breakthrough.

The First generation Honda Insight is still the mileage champion among cars ever sold in the US, even though it has not been built since 2006. The battery in the Insight was not powerful and only provided assist and regeneration of a small portion of the acceleration and braking forces. Even today to get the best mileage from an Insight you minimise battery usage.

Pulse and glide is not better for fuel economy in any gas electric hybrid due to the sum of losses involved in energy conversion. I know from driving my Insight for over 30 k miles what works and what doesn't work, having average 67 MPG for that distance.

I could have achieved better mileage with an accumulator and a hydraulic drive like I am describing here and my Insight had a dead battery at 45k miles, replaced by Honda under warranty. Cost out of warranty would have been close to 1000 gallons of fuel.

The drive in this discussion has a life expectancy of 500k miles, and the accumulator would be close to the same.

Most people here understand the massive increase in fuel economy of pulse and engine off glides. This design allows you to do exactly the same thing, with on huge exception.

In the pulse you store energy in the mass of the vehicle itself, energy you recover in the glide with no fuel consumption with the engine shut off.

The vehicle I am going to build will do exactly the same thing with one difference. You pulse the engine to restore the pressure in the accumulator and use the energy in the accumulator to continue at exactly the same speed, using no additional fuel, until the accumulator pressure has dropped by 66%. Then the engine turns back on and you repeat the process.

In conventional pulse and glide you encounter exponential increases in total aero drag as you speed climbs in your pulse. My system has no such issue since the pulse is directed to increasing accumulator pressure, while the infinitely variable drive continues to apply the exact same power to the wheel, by constantly changing the stroke position and the resulting displacement. When the accumulator pressure is depleted the engine starts and re pressurizes the accumulator while the stroke position of the drive is reduced as that pressure rises in the accumulator.

Pressure drops, stroke increases.
Pressure rises, stroke decreases.

The engine or any other fuel supplied power source you choose, is the servant of the accumulator. It is not directly connected to the wheels, unless you eliminated the accumulator. This allows the engine to either run at best BSFC or shut down and use no fuel. It doesn't matter what speed you are going, what grade you are climbing, or what you average speed is, the only difference is the time the engine is running. Stuck in crawling stop and go traffic and it might only run 5% of the time. Climbing Pikes Peak it would run 100% of the time. The engine needs no throttle plate, so pumping losses are reduced and throttle control is eliminated altogether.

The whole system is configured and designed from the principle of the lest amount of parts for the greatest benefit, which means a vehicle that cost less to build than anything current available. Not $100k, $50k, or even $20k vehicles. The cheapest new car today in the US market is the Nissan Versa at $10,900. This vehicle would cost less, because it would use 25 to 30% fewer parts. Parts that cost a lot to repair and replace would simply not exist.

My reason for building this myself, is the claims I have just made are, quite frankly, hard to believe. Only when companies actually experience first hand the demonstration of the technology and it meets expectations will they begin to consider building vehicles.

I went through a Nissan factory shop manual for a 1983 280ZX and what I am describing would eliminate over half of the parts and repair procedures in the shop manual.

All manifold throttle controls.
Clutch or torque converter, including controls and clutch hydraulics.
transmission
differential
prop shafts
brake system (except for emergency brakes)

The engine can be redesigned for producing power at a precise RPM and load range, with reduced strength in connecting rods, bearings, pistons, as well as many other components that must handle much higher stresses involved in high speed operation. Max engine speed would be about 3500 RPM, and this allows applications of current HCCI (homogeneous charge compression ignition). This is currently under development by Argonne labs with thermal efficiencies approaching 60%, compared to your vehicles average thermal efficiency at 17%.

My goal is to build a vehicle that can travel a mile on one ounce of gasoline at speeds averaging 40+ MPH. I have the funds,technology, and the machine shop working for me today.

Battery-electric power could also provide accumulator pressure, so don't think for a second that this design does not include that configuration. In fact as previously mentioned, since the motor has few connections to the vehicle, you could use either batteries and electric motors gasoling engine (or diesel) or a combination of those power sources.

regards
Mech

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Old 01-12-2012, 12:08 AM   #32 (permalink)
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Do you have any examples in running vehicles, or a rough estimate of when you'll be ready to showcase your product?
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Old 01-12-2012, 12:32 AM   #33 (permalink)
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Ecky, the linked utube video is of the only example in existence at this time. I would like to see the whole vehicle in operation before the end of 2012, but most people understand predictions that depend on other people to finish the stages in construction are mostly guesses.

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Old 01-12-2012, 05:14 PM   #34 (permalink)
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Pardons for being another speculative tailgunner, but our curiosity is peaked by your project. Good luck.

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Old 01-12-2012, 05:32 PM   #35 (permalink)
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How do you plan to get around the low power density of the accumulator? What kind of power storage are you looking for the accumulator to hold?

Sounds like it has promise as a liquid fueled vehicle. Honestly it doesn't make any sense to power it with electricity as it would be more efficient and cheaper to just use the electric motor for propulsion.
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Old 01-12-2012, 07:01 PM   #36 (permalink)
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My energy density is in the liquid fuel, where your 400 pound battery equals one gallon of fuel at 6.5 pounds.

The accumulator is a capacitive storage device which can recover the energy of a one 70-0 stop in 25 revolutions of the wheels at 80+% efficiency, wheel to wheel.

How efficient is your electric car in the exact same regeneration scenario? About 30%. If you believe it is more please provide documentation to support your position. This is especially significant if you do not have some form of transmission to spin the generating motor at high enough speeds to actually recover more energy, to say nothing of the controller or battery you need to accept energy at 100+ KW per second.

Don't use the position that we are hypermilers and do not have to stop that quickly. Hypermilers are a minuscule percentage of the driving population. Even the best hypermiler gets caught by red lights at precisely the wrong time.

The accumulator is better compared to a very high power capacitor. To compare it to a battery is a fallacious argument. It serves as a super high capacity recovery and reapplication energy storage device, without the cost, or deterioration involved with a battery. Lets at least compare apples to apples.

This drive will make electric cars more efficient, but that is the topic of a separate post where certain information must be understood and applied to realize the potential. It's commonly called a launch assist rear axle in the front wheel drive vehicle like the leaf.
On a deserted country road with no traffic or traffic lights it would not help, but that is not the real world in which most of us actually drive.

The source of energy can be fuel or electricity as I said before, but for the purpose of this discussion just consider the liquid fueled example.

Now lets get into the more theoretical. How much has battery technology improved in the last 5 years? I keep hearing about the breakthrough, but I see no breakthrough, even at a cost of $100,000 unless you want to use something like the NASA flywheel battery.

Combine this drive with a constant load HCCI engine, like the one Argonne Labs is running today, at efficiencies approaching 60%, then you have today's technology and 150-200 MPG on renewable liquid fuels that can be custom engineered for the engine and requiring no after treatment for emissions because they are that clean to begin with.

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Old 01-12-2012, 07:34 PM   #37 (permalink)
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I'm quite aware that the efficiency of regen on electric hybrids is relatively low, 30% sounds about right.

I also realize that an accumulator is similar to a capacitor. My questions were due to the fact that an accumulator is so similar to a capacitor and for your application it would seem that it would be better if it were a bit more battery like to decrease the on/off cycling of the engine. I'm thinking that your engine is going to have to cycle on and off quite a bit to keep that accumulator in its designed pressure range, unless the accumulator is quite large. That is where the energy density question came in.

So, I guess my real question is how do you plan on minimizing the cycling?
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Old 01-12-2012, 07:42 PM   #38 (permalink)
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Good question. The duty cycle would definitely depend on the accumulator size as well as the engines size. My brothers Prius cycles the engine of and on frequently and before actually seeing that I had concerns about cycling frequency.

Back to a direct answer. The cycling would be a function of the average of energy demands. In the INNAS link in my earlier posts they stated an 11% average of engine on cycling. Much lower at low average speeds and higher at greater average speeds. My best guess would be about every .6 miles at 55 MPH and on for probably 20 seconds while powering the vehicle and charging the accumulator. That would make it close to 50% on and 50% off at 60 MPH.

That does not factor in the aero efficiency of the body which would reduce the cycling percentage. I have to guess again at probably 50-50 at 70 MPH. This would also depend on the size of the engine which would reduce the 50-50 to 40-60 or more.

It's hard to nail down any absolute figure but the overall 11% of the INNAS configuration through the whole European cycle is probably fairly close, but the percentage would definitely change depending on your average speed. I would guess at 45 MPH average it would be 45 seconds off and 15 seconds on. Probably about the same as the P&G ratio which is 2to3 to 1 ideally. Even the weight of the vehicle would affect the percentage.

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Old 01-12-2012, 07:46 PM   #39 (permalink)
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I would try to size the engine so the vehicle would be capable of sustained speed on a grade. Something like 70 MPH up an 8% grade would probably cover just about anything.

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Old 01-14-2012, 09:51 PM   #40 (permalink)
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Quote:
Originally Posted by botsapper View Post
Pardons for being another speculative tailgunner, but our curiosity is peaked by your project. Good luck.

botsapper, amazing rendition, and very very close.

regards
Mech

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