Hydraulics Blog

It would have helped if you could have explained the advantages of hydraulic hybrid vehicles to our sustainable energy future.

Just an idea; would some one give me a calculation (approximation)
if this is at all workable please?

If a hydraulic oil tank was pressurised by air (contained in an
exchangable cylinder) then would enough energy be available to
drive a car a sensible distance? (eg 100+ miles) Also,

Would it be cost effective for the air cylinder to be partially
refilled by an air pump driven by the braking, or rolling downhill?

That is, the pressured oil (as a transmission) could be more effective;
the air (as the fuel/force) is lighter to carry, cheaper, and abundent;
and the reactive braking / rolling pump power increase the miles.

Naturally, it's not over unity, but do the maths stack up, to
make it worth investigating please? many thanks.

jt.

Just one problem once the oil leaves the tank does work in the hydraulic motor where does it go from there the tanks under pressure. You would need two large tanks to get 100 miles the weight of which would make it inefficient.

"If a hydraulic oil tank was pressurised by air" Negative, The tank is not pressurized. A small diesel engine running at peak efficiency drives a pump which pressurizes an accumulator bank, which acts as a large capacitor bank if we were talking about electronics. This provides a "buffer" during acceleration to provide the instantaneous power needed during acceleration, allowing the internal combustion motor to be sized as small as possible for maximum efficiency. Hydraulic motors then provide the torque to a transmissions/differential then to the wheels (or in low speed applications directly to each wheel).

"Would it be cost effective for the air cylinder" I'll stop you right there... there is no air cylinder.. or air anything (except whats in the tires) in a hydraulic hybrid.

The way I see it, the greatest advantage to a hydraulic hybrid is the extremely efficient regenerative braking. The hydraulic motor/s act as a pump, when they are not being used as a motor, which re-pressurizes the accumulator bank during braking, re-couping the energy used for the acceleration. As with all hybrid technology, the prime mover is still an internal combustion engine, which in this case can be sized much smaller than if the ICE were directly coupled to the transmission/differential. The key to the Hydraulic Hybrid is ample accumulator storage for acceleration.

All standard Heavy equipment out there is running on a Diesel/hydraulic hybrid system, and has been for decades. It is a Technology that is proven for low speed high torque applications.

Personally (even though I work as a Hydraulic/Pneumatic system designer) I doubt Hydraulic Hybrids will become a mainstream commuter vehicle option. However vehicles such as city busses, garbage trucks, mail trucks, delivery vehicles, could benefit from the hydraulic hybrid system, as they make frequent acceleration/deceleration cycles, which would optimize the system.

I'm not sure, but are hydraulic motors more, or less efficient as electric motors? I would think efficiency would be the primary concern before choosing one over the other. How about size and weight? Given the same size/weight, do they produce power on an equal basis? Which is more efficient, (given equal size/weight) a generator or pump? I'm not too knowledgeable about hydraulics, but I believe the electric motor has the highest efficiency.

A variable, bent axis Hydraulic motor at full displacement can average in the 90-95% Efficiency range. Similar to a motor... but the hydraulic motor might weigh 1/20th the weight of the same Electric motor providing the same power. But oil is heavy.. hoses/fittings/pump/accumulators etc adds up. You see where I'm going...

RV, Is anyone working with light weight substances with fluid-like properties, perhaps a malleable plastic, that would be easier to seal (thicker) and provide a weight advantage?

Mercury as a fluid metal is the opposite end of this idea, but gives rise in my mind to the possibility of a substance at the other end of the weight spectrum.

Is density mandatory in all fluids? Do all substances with fluid-like properties have great density?

CJM

Yes, various fluids are available for use in hydraulics, for example, Boeing uses a fluid called Skydrol in their systems for use in airplanes. They use Skydrol for 2 reasons, its lighter weight then standard hydraulic oil, and its fire resistant. The problem with skydrol, is it will eat the rubber right off your boot, peel opff all your paint and leave you burning wherever it comes into contact with your skin. Nasty stuff. Other fluids are comonly used, such as water glycol, (Ive even seen a guy use strait tap water(Not recomended). When choosing a fluid, you have to keep in mind that using something unconventional might make it hard to find parts with compatable seal materials, and operating viscosities. The short answer is: If you can find parts which will operate with your fluids charecteristics in the overall system, it can be done, (But I would stay with conventional oils if I were designing a system, as its much easier to spec parts, and things are generally MUCH cheaper)

Dear Mary,

So how does hydraulic parasitism make an advantage compared to electrical drive by wire? Please show calulations of energy lost at each conversion step. fuel to engine to battery, battery to motor, motor to pump, pump to actuator, actuator to steering rack, Also added weight of system. For ease of calculation you may ignore frictional losses. Then Calculate for Fuel to engine to battery, battery to motor to actuate.

Thank you.

milo

Well, thanks for the replies; just a crazy idea guys.

jt.

DaS Energy is not only in agreement, it is light years in front.

By use of hydraulic motive energy, and a +50* Celsius heat source our one litre fully recycling turbine engine having one only moving part, rotating at sixty revolutions per minute produces 1,200 Hp and has no Carbon emission.

The other splendor of this engine is that it makes good use of captured Carbon. So instead of the high cost to bury it, one seals it in a turbine and whola a turbine-generator in place of only being able produce 350 megawatts of electricity now turns out 123,000 megawatts.

Now I dont want to appear negative but here in Australia our Government is fully aware of the technology, and it been given free to Australia no catches.

However it would appear Coal, OiL and the piston engine makers have not yet suceeded in bringing maximun harm to our children and intend to see nothing happens to their technology and all Politicians are falling over backward to assist them.

I did it for the sake of the Children.

Peter Mckinlay. inventor DaSTurbine.com

What is Das Energy? This sounds to good to be true. How does this work? Jim

Hello Jim.

DaS Energy, DaS (Dad and Sons) Energy Pty Ltd.

Our turbine essentualy copies a steam/gas turbine, whereby a liquid is heated into a gas and the energy is utilised before the hot gas is condensed back into liquid.

The difference being where H20 delivers 350 megawatts, Co2 delivers 123,000 megawatts without increasing the fuel load.

The principal of working is, Co2 at 74 bar and +31*C is liquid. Heating of the liquid turns it into a gas that oddly enough behaves as if it were a liquid.

C02 at +50*C has a pressure of 10,000 bar.

10,000 bar pressure forces upon the turbine blade causing rotation, as the Co2 exits the turbine housing it is cooled down to +31*C (74 bar) and then returned to the turbine for reheating.

Cheers Peter

C02 at +50*C has a pressure of 10,000 bar

This statement still needs qualification...

Oh... wait, nope, Milo has qualified it

It's now qualified to be rubbish.

It is too good to be true. It works in one's mind only if one ignores the CO2 phase diagram, which shows that CO2 is a solid at the pressure and temperature described.

PhaseDiagram We posted this earlier and no one has refuted it.

Keep your money in your wallet.

At 10000bar CO2 is a solid.

milo

Milo,

At what temperature and 10,000 bar is Co2 solid?

Cheers Peter

As can be seen; at 10,000 bar and all temperatures below 350K (~170 degrees F)(77 C) CO2 is solid.

This phase diagram from: http://biofuelsdigest.com/blog2/wp-content/uploads/2008/08/carbon_dioxide_pressure-temperature_phase_diagram.jpg

It is clearest of those out there.

50 degrees C is (323 K); 323< 350; its a solid.

Best Regards,

milo

I think what he means is using hydrostatic drive systems to eliminate the mechanical coupling from engine and electric motor to the wheels.

I have found many references to the modern axial and rotary piston pumps and motors claiming honest efficiencies of 97+% at full rated load. I would tend to believe them being all of the large industrial and commercial equipment that uses hydrostatic drives has amazingly small heat exchangers or radiators for the hydraulic systems compared to the power they handle.

Hydrostatic systems do have a proven track record of being reliable and have been used in applications where they are ran day in and day out for decades in some machinery with very little maintenance They have a proven reliability far greater in terms of working life span than any typical civilian vehicle could ever need.

Modern high efficiency hydraulic motors are small enough to be fit inside typical vehicle wheel hubs and can still deliver the same at the wheel horse power that solid drive lines currently can do. Hydraulics can also evenly distribute torque to any number of wheel motors regardless of traction or slippage issues as well. True even split of mechanical effort can be easily done with hydraulics with simple valving far easier than how the electronic traction control and mechanical all wheel drive systems presently do it.

The main reason it is not used is its something new in terms of how the automotive industry and general public view it. Lack of familiarity has far more to do with it than anything else. Thus its not widely known for its capacity to work reliably and with long life expectancy's while doing everything in a simple way that currently needs complex electronics and computer systems to work.

The majority of people just don't know about it and that has always held back advances in technology and eficency in every thing designed.

GA.

Your a person I would dearly love to have speaks with.

The DaS pump is fully set out on CR4 inclusive of the internal sealed Co2 drive gas.

In short, cool Co2 gas pocket trapped above a collum of water implaces a downward force of 10,000 bar pressure upon the water when the Co2 temperature is raised to +50* Celsius.

The water being forced through a hydro turbine converts the pressure in Kw/Hp.

A flow rate of one litre per second, at 10,000 bar pressure on a 82% efficient turbine produces 926Kw or 1,200Hp.

The smallness of size to power ratio does away with the need of a gearbox, generator and or electric motor.

The engine has one only moving part, unlike all other types of piston engine.

The engine Methane fuelled will outperform any and all other piston engine running on any type of fuel. (A case of recycling waste to drive to work and anywhere else)

For these reasons the opposition to its market appearance not only comes from manufacturers but the highest levels of Government.

The same technology when used for base load power generation (Toshiba gas/turbine) produces 123,000 megawatts in place of the current 350 megawatts.

Not only are investors in Coal totally opposed to this technology but so is the highest levels of Government.

This is clearly demonstrated with Governments refusal to accept the technology as free gift, and further its refusal to provide any assistance at all to its development and or marketing, and further its insistance that captured Co2 be buried and stay buried rather put to use slashing the Carbon content of our atmosphere and providing a three hundred fold energy increase at no extra cost to every part of our every day lives.

Cheers Peter

"Co2 temperature is raised to +50* Celsius."

How is this achieved? You seem to have not mentioned anything about the part of the system that initially inserts the energy to heat the gas.

You do mention something about methane, but I don't understand your system completely.

So you burn methane gas to heat this trapped bubble of Co2, which expands, creating pressure on a column of water, which you then run through an orifice, and turbine to generate power. Please help me understand how this type of system can possibly generate 351 times more power than a traditional system. Also please help me understand how a heated bubble of Co2 can produce 145,000 PSI. 3000-10,000 PSI is where 98% of the components on the market operate, must be hard to find parts.

Please help me qualify this system for further analysis.

Hello RV2717.

You are correct in the Co2 bubble is heated, expanding to drive water before it. This piston like activity ceases when the release valve activates and allows the Co2 to pass through cooling on way back to heating creating next piston stroke.

So long as temperature outside the turbine is above +0* Celsius the turbine shall rotate at any Kw/Hp however its footprint is larger when outside temperature is low.

The one litre 926Kw/1,200Hp requires a heat of +50* Celsius, applied to the turbine casing, which can be supplied by burning Methane or any other fuel.

To calculate power output, one litre of water per second at nine bar presure produces seven hundred and twenty watts.

Example. Toshiba gas turbine-generator. 420 tonne Coal per hour produces +550* Celsius heat, creating 175 bar pressure H20 gas, producing 350 megawatts.

Co2 gas at +50*Celsius produces 10,000 bar pressure.

Co2 gas at +30*Celsius produces 74 bar pressure. 9,926 bar (+20*C increase) divided by 175 equals 56.72. +550* Celsius divided by +20* Celsius equals 27.5. 350 multiply 56.72 equals 19,852 megawatts. Multiply 27.5 equals 545,930 megawatts .

The parts required are a hydro turbine, water pipe, and one way valves.

Wikipedia can supply online phase graph (temperature versus pressure) of Co2 at Critical temperatures, and Supercritical temperatures.

Cheers Peter

This is still very unclear to me. (and no offense, but Your math figures are nearly meaningless, to me at least).

So.... you say its a turbine... which is confusing, considering turbines have no pistons, so when you say something like "piston stroke" it tends to be a bit confusing.

If you want to crunch some numbers, or provide some links to something useful, could you help enlighten me on how you have come up with this statement:

"Co2 gas at +50*Celsius produces 10,000 bar pressure."

That statement is missing quite a bit of information. In order to even begin to take it seriously, you need to qualify it with actual information such as quantity of gas in X volume at X temperature to start with density of X... which then heated to X temperature, increases to X volume @ X density in a chamber of X volume, creating X amount of pressure. Please provide your calculations or research links to prove your statements.

Because right out of the gate you are making statements with no resource links, or actual meaningful calculations, I cannot trust your numbers.

Please provide some real data to substantiate your claims.

Hello RVZ717,

No offence taken.

I not be an engineer but a simple farmer unable to speak the technical language so often used on this site.

Complete drawings of the Das Pump are on this site. A possitive action pump with no moving part if you discount the rubber ball floating on the water.

This pump supplies the head water to a hydro turbine which discharges back into the pump refill.

The pump stroke, ie the volume of water forced out a pipe is what I call the piston stroke as the device was first born as a Diesel engine utilising a turbo charger to inplace the air and normal Diesel injector.

Now instead of exploding gasses to obtain working force we instead use sealed in Co2 heated and cooled much the same as the mechanics in your fridge.

Type in Co2 temperature/pressure and many a site will come up with the answer and none yet have contradicted another. Wikipedia has the Co2 phase graph for both Critical and Supercritical temperatures.

California University open class on Hydro Power Generation has it that One Litre of Water per second with a constant pressure of Nine bar passing through an Eighty Two percent efficient hydro-generator produces Seven Hundred and Twenty watts.

Any increase in flow or pressure is so for wattage output.

No fuel required only a surround temperature above +0* Celsius !!!!! when using Co2.

Methane, the Aussie Blue Flamer burns at One Thousand Five Hundred and Ninety degrees Celsius.

Co2 Supercritical acts as if it were Water. +Fifty degrees Celsius is Supercritical Co2 TenThousand bar pressure.

Deduct +30 degtrees Celsius and Seventy Four bar pressure for gas reconstruction into liquid state.

Nine Thousand, Nine Hundred and Twenty Six bar pressure per second, divide by Nine

multiply by Seven Hundred and Twenty Watts.

Methane/Air, Seven Hundred and Ninety point Five burns per litre heating one to Two.

Three Hundred and Ninety Five seconds of Seven Hundred and Ninety Four Kilowatts. (6.58 minutes)

Turbine rotation Sixty revolutions per minute.

Cheers Peter

I am still as confused as when we started....

You say: "No fuel required only a surround temperature above +0* Celsius !!!!! when using Co2."

Then your very next sentence states: "Methane, the Aussie Blue Flamer burns at One Thousand Five Hundred and Ninety degrees Celsius."

You might see how i could be confused by these back to back statements.

So regarding your first statement, how can you make energy with no energy input?

regarding the rest (the second half) or your post, your calculations once again mean nothing to me, as you have still not qualified any facts/figures about anything. Please provide references to some real information when making a claim, otherwise no one is going to take you seriously.

I am confused by your CO2 numbers. I use liquid CO2 tanks for my welding gas sources. At 80F CO2 is only at around 600 PSI in my tanks and is still in fact liquid.(I can slosh it around)

I use the standard 50 pound liquid feed type (dip tube) tanks to refill my larger main CO2 tank thats stationary in my shop. My main shielding gas tank can hold 150 pounds of CO2 but has only a vapor output.

To get full transfer of three 50 Pound liquid CO2 tanks into the 150 pound tank I have to leave the last liquid tank out in the sun for an afternoon until it gets to about 120 - 130 F or else electrically heat it to that point. Then the internal pressure is about 900 PSI and will transfer the last tanks liquid completely into the big tank.

I assume my mechanical gauges are not extremely accurate and do not represent the real vapor pressure/temperature ratios of CO2 with any great accuracy. But they are not off by 10000 BAR in a 100 degree F temperature range!

Thats the numbers I relate to with CO2. The liquid in my tanks is likely on a super critical state or what ever term is used for being in the trans liquid/gas state when I heat it up to transfer it. Its not important to me other than it works for what I need to do.

I am not sure where you get the incredibly high bar pressure numbers for CO2 from. Unless you have it in a container that has been filled to 100% capacity at a lower temperature.

IF you do that with any liquid by placing it in a sealed container at a low temperature and then just adding a few degrees of heat to it the internal pressures of the container will go incredibly high with very small amounts of energy.

Sorry but I see no over unity or super efficiency here. Just miss understood physics and math.

I am sceptical of every alternative energy system until its proven to me personally in person or can be built by me and actually work as described.

Has your device actually been built and proven to work? If not I have no further interest in your work until it has been built and proven to work as witnessed by real people who have practical working knowledge in the fields that your system uses during operation. I know how to make engines that seem to run without gas or even a carburetor or fuel system! Mechanical slight of hand is not hard to do!

I have my own weird stuff to keep my mind occupied at this time. I have yet to ever here of a 123 gigawatt power station ever being built or even properly planed on this planet. Let alone one that doesn't use any naturally occurring fuel source in vast quantities! Governments and politicians are greedy and clueless but would still jump all over something like this because it has insane profit capacity if it could be shown to work. And what I mean by work is real life full load operation for weeks on end.

As far as I know if you really want to change the world for the better just dump your full research and information along with working schematics and proof of device operation all over the internet. It wont take but a day before others will build it and then tell the world about it actually working as well. If you really think the government can stop whats on the internet from becoming public knowledge explain why they cant even stop the junk mailers and phishing scammers and they can even track them to the house their computer is at!

I have seen a few AE devices that do in fact seem to run outside of conventional wisdom but countless more that are just fools junk with little or no rational thought or practical knowledge behind them and could never be built let alone work.

I do not believe in over unity or perpetual motion but I do believe in using non standard power sources to account for the seemingly over unity numbers and perceived perpetual motion effects of the very few that can be proven to work.

We are floating in a infinite ocean of energy and some devices do seem to be able to tap that energy and really can convert it to usable power by our definition but still the machine as a whole still has to obey the laws of physics! I don't mind bending the rules but if the actual point that the supposed added energy comes into play cant be accounted for its just fools junk in my mind.

Hello tcmtech:

The schematics of the DaS Turbine are posted all over the internet, see CR4 and DaS Turbine.com.

Do I have need for your interest given the world wide interest in our work.

The data is as verified Wikipedia, Qld University, California University, Oaklohoma University, Indian Government.

Viewing of the working model is available by contact with DaS Turbine.com

Cheers Peter

I got absolutely nothing from the DaSturbine.com website. Even the fact sheet has no facts...

So i guess above any other question i wish you to answer is:

How much energy in the form of a fuel (your saying methane) will it take to make 1 MW of electricity?... (or any amount you wish), just please correlate the amount of chemical fuel (and energy contained within) you need to burn in order to heat that quantity of gas/water for the system to work, and provide the electrical output for that quantity of fuel...

...and please provide the data for us to take a look at. This should be very easy considering you say there is a working model which can be tested. I would absolutely love to believe in a system that does what you say it does...

If these universities (and the Indian government) have done research on this technology please provide links to the papers...

Unfortunately you are trying to convince engineers and scientists about this technology, without the use of real facts/figures.

I want to believe....

Hello RVZ717,

Never before have so many got is so wrong for so long.

Can only quote the figures as written.

Co2 at 74 bar pressure and +31.1 degree Celsius is liquid.

Co2 at 10,000 bar pressure and +50 degrees Celsius is gas.

H20 at 1 bar pressure and +99 degrees Celsius is liquid.

H20 at 175 bar pressure and +550 degrees Celsius is gas.

Both transform from liquid to gas then back to liquid, using the same process.

Co2 at 1 bar pressure and +1 degree Celsius, pressure increasing with temperature, means so long turbine round enough any wattage can be generated at any temperature above +0 degrees Celsius.

For racey things like sports cars the one litre turbine +50 degrees Celsius is my choice.

Cheers Peter

Do you have an actual link to a website that has real useful information? All I have found is the typical cryptic crap con men and AE scammers use. I have not found any useful information in any websites.

All I have found so far doesn't have anything even remotely resembling real engineering facts, figures, schematics, or technical information. Just off topic irrelevant concepts that don't have any solid basis of application let alone real function.

To be honest what I am finding looks like standard issue alternative fuels para science logic and typical scam artist websites. What I have found and read about here on CR4 looks and sounds the same way as well.

It may sound like something to you and make sense to you but from the technical stand point what I see is closer to high school science fair speculation derived from limited knowledge of the concepts being discribed than real engineering technical literature.

Sorry but thats what I am seeing.

You are not alone, I am seeing the same.

Co2 at 74 bar pressure and +31.1 degree Celsius is liquid.

Co2 at 10,000 bar pressure and +50 degrees Celsius is gas.

So adding 9926 bars of pressure does nothing to compress the Co2 because it is overridden by 18.9 degrees of temperature

http://www.chem.queensu.ca/people/faculty/Mombourquette/Chem221/5_PhaseChanges/PhaseDiagrams.asp

fyi 5.11atmospheres = 5.177 bar

304.2 = 87.89 Degrees F

50 degrees Celsius = 122 degrees F.

You are saying that way up at the top of the phase diagram where the "bar" ~ (atmospheres) would be 10,000, at the 304.2 temperature on the X axis, the CO2 is a gas?Looking at the phase diagram we can see thatat87.89 degrees, anything above the line would be liquid or solid, gas is only below the line segment of triple point- critical point and its extension.

Something does not compute...

milo

I wouldn't trust Wikipedia to tell me water is wet. And I have no clue who the other places are. For the right donation or black mail I can get my local universities to say anything is true. Especially if it means that by them saying yes they can get a load of government grant money to pursue it even full well knowing its fools junk all a long.

As stated before. I am sceptical. That does not mean I don't think you may be right and do have something great! without real data and working numbers ( Not that Greek alphabet crap) I wont say you are right or wrong yet. I need fuel usage numbers, actual system as constructed and operated data, and the end energy output results. If any device requires a "secret modification that cant be disclosed or a special chemical concoction thats base chemical composition (unobtainium is the common word for it) cant be disclosed as well then I will put you in the con artist file.

However show me real numbers, the real devices used and real descriptions of how the are used or modified and the real output numbers in such a way that I would feel confident that I could build one myself and I will give you my full support in any way I can!

I can spot AE con men far better than most. So far your on the horizon but that doesn't mean your a con to me so far. Just someone with something new I don't have full or even partial knowledge of yet.

I will be looking for what I can find in the next day or so and I will likely have some real questions too!

Well that took me all of 5 minutes to find out absolutely nothing useful.

As I see it its a high pressure version of the old old sewage pumps from the 1800's that used a combustion chamber and liquid piston (sewage water) to pump large volumes of waste water up short elevation changes. I don't recall the name but it worked very well had very few moving parts (floats and a set of valves for fuel and exhaust) and was possibly the most efficient pumping system of sewer water ever created. Or so claimed by the people of the day.

If you have built a high pressure version of this system and are using the closed loop circle of water to drive a turbine in order to get mechanical energy out of a combustion process you are correct on the high power and efficiency part. That old design could conceivably be built to monstrous design proportions!

However if so the water or liquid medium is possibly just absorbing the CO2 and other gasses and would eventually reach saturation point and thus nothing is being fully eliminated but simply stored. As soon as the very high system pressure is released it would fizz out like a open bottle of soda!

And this is just all a guess though too! I could be completely wrong on the concept and operation. Mostly wide speculation based on very little useful information and vague recollections of antique engine designs.

Hello tcmtech,

Thank you for the information on the old sewage pump. I have not seen one myself but they sound exciting.

The DaS Pump may in fact absorb some Co2 but I have not seen any pressure losses to indicate such.

Our testing shows there is no pressure losses in converting from gas to liquid drive.

That is to say as cool bubble of Co2, trapped between the surface and top of sealed cylinder, warms and expands it forces the water before it.

By having the pressure cylinder located above the DaS Pump the gas pressure is utilised twice, 1st when pushing the water out the pump, through the turbine and on into the pressure cylinder. At point of exhaust valve opening the high pressure gas which is contained beneath the water overhead rushes up forcing the water out of the pressure cylinder down through the turbine and refills fully the DaS Pump.

The warm gas now located in the pressure cylinder may exit into the cooling coil thereby stripping away the back pressure as the second stroke of water fills the pressure cylinder again.

The cooling coil is conected to the DaS Pump cylinder which receives a dose of cool Co2 each stroke.

A simple model can be made using 100mm PVC pipe and tennis balls.

So long as the Co2 flow in is slower than the water return, the cylinder fills and all valves close setting the action in motion.

Any gas can be used, however so far we have not found a gas with suitable temperature difference for domestic use.

Cheers Peter

Still, the original nut case is here. (me)

Thank you for vote of confidence in the hydraulic transmission.
While I have always thought electric was the "way to go" (weak!)

There are (I'm told) distinct advantages to using hydraulic (oil)
pressure. As remarked up above. Thank you.

So, please would anyone advise me on equip. for a vehicle?
The type / size / etc of motors - 4WD, and to suit braking.

Any info would help please; capacities, pressures, specs, etc.
Yes, a manufacture will advise me - from their standpoint, and
unbiased information is always preferred. (at least by me.)

I have an outstanding idea for a prime mover - which is going
around in my head, and I would like to "know" if I made it, that
it would suit the purpose, of these hydraulic motor drives.

Thanks for your help guys.

jt.

You like my gold watch? My grandfather, on his death bed,
sold me this watch.

For short bursts electric can in fact challenge hydraulic! However on the high load and long haul cost comparisons hydraulic walks all over electric and most mechanical systems when it come to delivering power to more than one or two wheels!

Without knowing how heavy, how fast and what total power you have available its almost impossible to come up with realistic numbers.

The hydraulics manufactures websites typically do have good estimating and converting formulas to work with and from there you can engineer your system from that.

Good luck and I hope you come up with a simple reliable system!

Hi tcmtech,

Thank you for your replies.

My idea is to have a small hydraulic motor on each of 4 wheels
of a normal car; weight approx. >800kg with passengers.
(nothing new there.) Also:

The speed does not have to be anything extreme (only from a
marketing point) everything comparable with a normal car is ok.

What would be the power required from a prime mover? e.g.
I estimate my "engine" should provide 6000 lb per square inch
pressure, with a volume displacement of ?? >10 cu. inch/sec.
I'm unsure of the maths, but if I need to double the volume,
(for the requirement of the 4 motors) e.g to >20 cu. in/sec,
what would be sufficient? i.e. numbers in pressure, volume, etc.

Simply: what would I need in pressure and volume to power
the cars 4 motors correctly? i.e. To power like a normal car.

This would then determine the design output required of my
prime mover. (achieving it is another matter.)

There are other questions: like air reservoirs for the braking etc.
but I need to see if the principle numbers stack up first please.

Many thanks for your help tcmtech.

jt.

The answer's to your questions cannot be reliably given. There are MANY factors when designing a Hydraulic system like you speak of. I design Hydraulic systems every day for a living, and could not generate you any numbers from the information at hand. You most likely should pick yourself up some good reading material, and reference books, and go through the (quite expansive) whole process. The selection of your prime mover cannot be made until all others calculations have been preformed.

When designing your system, you start with the "Work" and work backwards through your system, until you end up with the exact prime mover you will need for minimum performance requirements.

Hello RVZ17, As a hydraulic designer may I walk you through the DaS Pump?

Firstly bend a metal pipe and fill with water then blow on one end. The water comes out with the same force you blew in. Now if you make one end of the pipe longer, you can make the water travell a given distance by possitive force and by its release have the water return. If you insert a third pipe into the U bent pipe, a valve can be tripped allowing all the gas force pushing the water up, to go to opposite end and push the water down. Thus the force is used twice but its energy requirement cost once. This leaves the making of the gas force. This gas force must be constant and is acheived by heating for expansion and cooling for contraction a method long employed by the steam boiler. Having now acheived the water going up and down at same force one needs to obtain a one way rotation of the turbine by split inlet/outlet seeing the water flow one way through the turbine.

Hydro generation output on 82 percent efficient turbine is 720 watts per l litre flow per second at 9 bar pressure.

Countrified testing has been taking hose uphill untill pump blew up. better casing needed! Turbine testing has been with micro hydro Pelton wheel and generator. Wattage unkown but everything spinning.

Cheers Peter

I think your idea is worth developing further myself.

There are a few primary factors to deal with first. They may seem not so important but they dictate how everything fits together.

Relative to other vehicles is too wide of range. Average in one location is tiny and completely impractical or to big to maneuver in another.

How fast are you thinking? A City dweller that doesn't see over 40MPH is way different than rural person as myself that will do 85 MPH on the interstate!

Acceleration. Old lady on a empty road or heavily loaded and merging with interstate traffic?

Normal car. hmm... I have more adverse road conditions than many and do need to haul and tow trailers myself. An average car for me is about 3400 pounds and has at least 200 Hp. Around here 800KG with passengers wouldn't even be let on the highways. We call vehicles of that size golf carts!

So as you can see the basics need further clarification. I myself lean heavily towards bigger and more robust. In a crowded city my normal car would be to big to be practical in many parts of the world. But yet the normal vehicle in those parts of the world would never cut it here.

Practicality in the target market makes or breaks a product.

"Practicality in the target market makes or breaks a product."

Bingo!

ONE size doesn't fit all.

Why city dwellers need 4wd SUV's I don't know; I had one when i drove 20 miles each way along lake erie to steel plant on all shifts.

Reframing automotive engineering problems into target market problems is the first real step toward doing real engineering in this area by BETTER DEFINING THE PROBLEM IN TERMS OF APPLICATION, rather than just gee whiz techie gizmo answers in search of a problem.

Good Thinking.

milo

I think the first rule is define the market. That is, the major segment.
Yes, there may be profitability in e.g. army tanks, but a niche market.

I would suggest (here in the UK) 80 percent of the population drives
about in a small (relative to the US) 4 door car of about 1.6 litres,
does about 90mph tops, (speed limit 70) and weight >800kg.

Yes, we have been slowly moving to the larger SUV but these will
struggle with the economics of fuel prices increased road tax and space!

If the project is successful, or lends itself to a different size of vehicle,
there is no problem finding new targets; but first, let's be on the money.

There we have the target spec. folks. If we can crack this market.....

jt.

I had to leave home when I was 3 year old... couldn't get on with my mother.

Given the target market I could see something with a 40 - 60 HP diesel or alternative fuel based engine driving a simple variable displacement pump that would give an all wheel drive capacity with an incredible torque range while still keeping the engine at optimum RPM's for the load its under.

The pump would need to be about 1.5 times larger at maximum displacement than the wheel motors. That would equate to a total drive line ratio range from near infinity to a 1:1.5 overdrive. Being able to keep the engine at maximum torque while continuously increasing vehicle speed just by hydrostatic transmission ratio change would give you a very snappy feel with minimum engine power!

I do know for a fact what you would need is already off the shelf pumps, flow divider valves, and wheel motors so cost outlay is going to be low simply due to minimal custom parts needed for a basic system.

I don't know the exact numbers but I could make a reasonable guess your vehicle could easily do 80MPH on level ground while loaded in most conditions. The very high reduction ratios variable displacement pumps can produce would give it outstanding low end torque despite very minimal engine power. With a high efficiency engine and good aerodynamics I think you could have a full all wheel drive vehicle that seats four reasonably comfortable with a very snappy driving feel yet have outstanding fuel economy as well. Maybe in the 40 -70 MPG range in realistic driving conditions.

If split between all four wheels the flow rate for 15 hp per wheel is only about 15 GPM at 1500 PSI each roughly. Thats easily handled with 5/8 inch hydraulic hose. I would design it with a 4500 - 6000 PSI peak pressure capacity to the wheel motors though. The flow rates at that pressure would be low but the torque would be many times higher than that at maximum flow and would be what gives the snappy high torque feel.

There are many ways the system can be built and also many different flow and pressure rates that can be used as well. What I went by are common flow and pressure capacities typical pumps and motors can run at with good long term life expectancy.

Given a good reliable engine and drive system I think your vehicles would have the body rot off the frame before the engine and drive train wore out! As long as you don't put to much useless junk (American design) into it and keep it simple but user friendly you may have a real product that sells!

Perhaps make them a modular design so both passenger car and light pickups use common systems and component layout so parts are simple and easy to swap between models and you would be even further ahead! Less production parts and tooling costs.

Excellent, so if we want to design a car that can accelerate from 0 to 60mph in 6 seconds and the car weighs 4000 lbs we can work that backwards to calculate the motor torque, cubic inches per rev (CIR), the flow, the PSID across the motor(s). The starting torque is about 3 times the average torque when accelerating a motor. This assume the pressure supply is constant and it probably won't be. Differential equations will be required here. It takes about 10 HP to maintain a constant speed at 60 mph. To make this simpler why don't we assume there is just one hydraulic motor. I think the goal would be to shave off some the 40-60 HP and get that number lower so that there is enough power to maintain a steady speed at 60 mph and a little more power to keep the accumulator(s) charged. Then rely on accumulators to provide burst of power when accelerating or to absorb energy when braking. The accumulator would need to be big enough store all the oil while decelerating. Since the amount of energy that is dissipated is proportional the the velocity squared there are going to be limits to how fast the vehicle can go and then stop and save all the energy. If this velocity is only about 40 mph then hydraulic hybrid vehicles will be limited to city 'stop and go' traffic. This limitation may be a killer but we don't know until we do the math.

One problem I see right away is hydraulic accumulators are heavy per unit of volume and the higher the pressure and greater the volume the heavier they get.

It would be nice if someone could put out some real numbers relating to the energy required during a 0-60 MPH 6 second acceleration of 4000 pounds of vehicle.

The thing I see with the accumulator method is the total energy that can realistically be stored in one is small compared to the over all energy being used on average by the vehicle. There is no point on trying to recapture the dynamic breaking energy if it only adds up to a small fraction of the total amount used during actual normal driving. It would end up costing more than what its worth in realistic gains. The added weight and complexity will severely cost driving energy and will drive up manufacturing costs as well. A 5% gain in one area is not worth anything if its side effect causes a 10% loss elsewhere.

With full electric vehicles its simple and easy to do regenerative braking only because the battery that powers the vehicle can hold loads of energy. Hydraulic accumulators are more like fluid capacitors. They work great for very short bursts of energy but their size becomes a problem if you try to use them as batteries.

The industrial hydraulic accumulators I have been around are used as system shock absorbers on excavators and other construction equipment. They smooth out shock loads during normal operation very well. BUT a 1 gallon capacity accumulator that works at 4500 PSI weighs nearly 50 pounds!

Factor in you may be needing possibly 30 gallons or more of capacity at 6000 PSI peak to be effective for dynamic breaking and return during acceleration and now you may have 1/4 of your total vehicle weight just for one component. Under normal conditions thats a 1000 pounds of dead weight that doesn't help anything! It will increase stop and go efficiency some but overall it will take away more than its gains justify.

Plus a hydraulic system for a typical vehicle in the size range you are thinking would likely need less than 10 gallons of fluid total. Just adding the accumulator means you need 30 or more gallons of reserve fluid you need to carry around even when your not using it. Plus the accumulator takes up more space than the hydraulic tank does too. Just having the accumulator and fluid tank means you need to hide an equivalent of a pair of 35 gallon drums worth of physical volume in your vehicle design.

The highly efficient mini vehicle will become a typical fat American pig real fast. And I can tell you for a fact regardless of drive system efficiency 60 HP on a 4000 pound vehicle is going to be a gutless wonder at anything over 40 MPH. But on a 1500 pound vehicle its still going to be fun to drive!

I have driven vehicles with 80 hp engines on 2200 pound frames and you cant pass anything on the road. A strong head wind or a average hill kicks your ass. The 30 HP it takes to maintain highway speed is easy. The additional 100 HP you need to maintain speed during winds or hills is why vehicles need the bigger HP engines. If it doesn't have the power to maintain itself under typical realistic driving conditions it doesn't take to long for the word to get around and sales drop. Inconvenience out weighs the operational cost gains and very few get sold.

A simple hydrostatic drive system will weigh about the same or likely less than its solid mechanical equivalent. It will have equal to greater overall efficiency as well. But once you add all the other stuff it looses all of it advantages real fast.

If you focus the design towards being a more city type application vehicle with it being a good simple people mover or a small delivery or goods transport type vehicle its going to be a good viable concept. Trying to build it for an application like I need will take a 3500 pound vehicle with at least an honest 200 HP before I would even think about buying it. In typical driving I don't use anything near the 200 HP but when I do need it I have to have it there for me.

My old pickup was 6200 Pounds and had a 400+ HP engine with a four speed automatic with torque converter lockup on all four gears. The transmission had a full electronic control system that I wrote the program parameters for myself. It was the funnest pickup I have ever driven! The massive low RPM high torque engine moved it around effortlessly in every type of driving condition in cluding pulling twice its own weight at interstste speeds! Yet it also had reasonable fuel mileage as well. It set the standard in my life of what a vehicles power should be. And because of it I am biased!

But for a city person it would be completely impractical in size, power and overall application. What suites me is not the same as what suites a city market. They have the majority of people that need the smaller light weight high efficiency vehicles that are within a reasonable price range. I think focusing on their target market is far more practical than focusing on mine.

A vehicle with a curb weight of around 1200 - 1800 pounds and seats 4 guys my size, 6'3" 250 pounds, and has good snappy in town drivability with great fuel efficiency would have a reasonable American market potential but more likely a much larger world market potential. Same with a basic pickup or goods transport type vehicle with seating for two with a payload capacity of around 800 pounds.

Just my thoughts.

"It would be nice if someone could put out some real numbers relating to the energy required during a 0-60 MPH 6 second acceleration of 4000 pounds of vehicle."

I used E=(1/2)*m*v^2 and divided by 6 sec to get about 146 HP or a little less than 109 KW. I used Mathcad to do the calculations because it makes it trivial to switch back and forth between metric units and English units. I should have picked metric units.

Of course this assumes the power is constant but not the acceleration. I am not worrying about friction and air resistance so the numbers are ideal

But this gets to the heart of the problem. A lot has been said and no one has done the calculations to back up what they have said.

"The thing I see with the accumulator method is the total energy that can realistically be stored in one is small compared to the over all energy being used on average by the vehicle."

The accumulator doesn't need to store energy for the whole trip. It is just a means of store the kinetic energy in the form of potential energy while decelerating and doing the opposite while accelerating. When I did the E=(1/2)*m*v^2 calculations I had the total energy while at 60 mph. Now how big must the accumulator be to store that amount of energy?

This quickly turns into an optimization problem with constraints. Obviously the accumulator must be able to hold all the oil during braking and a lot of this will depend on the size of the motor and the wheels because this determines how many revolutions of the motor the accumulator must hold. It is obvious to me that the accumulator doesn't need to be very big if the vehicle stops quickly but then the accumulator will not hold much energy. If the vehicle wants to slow to slowly then too much oil would need to be stored. Obviously a swash plate is need that would have a low pitch when slowing down slowly and a higher pitch when slowing down quickly. After all the same amount of oil should be saved whether slowing down slowly or quickly because the potential energy saved in the accumulator needs to be equal to the kinetic energy while moving.

So if the accumulator is pre-charged to 10000kPa ( 1450 psi ) how big does the accumulator need to be? How much will the pressure increase?

BTW, did you notice that I am assuming all the energy is saved in the accumulator? If all the energy can be returned then do you really think you need a 60 HP motor just to maintain a constant speed? What if 80% can be returned? What size motor do you really think you need?

I am far too busy^(lazy) to run all the numbers, but UPS has done them all for a UPS Truck, and have their (Rough) designs posted all over the inter-webs, have a look-see. Other good info as well, which can be found via diligent google searching.

I believe you will wind up with a large can of worms if you try to simplify everything down to the point you currently are. From the sounds of things, you need to hire an Engineering/Hydraulics Guru to help you in the planning phase of your project. Proper planning down to the last variable will most definitely save you much time/headache in the overall scope of your project, even if it seems like more than you need at the time. Time and Time again, its the details that make the difference.

I believe I said it before, you should start with your actual (worst case scenario) Work/Energy, and start working backwards through the system, until you end up at last, with the prime mover(Your ICE (Internal Combustion Engine)). Be sure to add up all your losses through each and every component... The last thing you want is to spend a bunch of time planning, only to realize when you have your working model, it doesn't work as planned.

"but UPS has done them all for a UPS Truck, and have their (Rough) designs posted all over the inter-webs, have a look-see." I have seen the UPS truck at the IFPE shows in Las Vegas. Parker has special light weight, high pressure accumulators installed in the UPS truck. "I believe you will wind up with a large can of worms if you try to simplify everything down to the point you currently are." I didn't get into details because they would make peoples eyes glaze over. I know what most of them are. I definitely know how to approach the problem. "From the sounds of things, you need to hire an Engineering/Hydraulics Guru to help you in the planning phase of your project." I am a Engineering/Hydraulics Guru. I do similar calculations all the time, just not on hybrids. I can solve the systems of differential equations and then use an optimizing program like http://en.wikipedia.org/wiki/L-BFGS to optimize the design given the constraints. This isn't a big deal because most CAS packages have these capabilities. The trick is knowing the application and having accurate numbers to plug into the formulas. I agree about the details. "The last thing you want is to spend a bunch of time planning, only to realize when you have your working model, it doesn't work as planned." That should never happen. I know that a model and simulation can never prove a system will work. It can only prove a system may not or won't work. The big problem is figuring out how all the components will work and I will risk upsetting every here by saying that I have a lot of contempt for mechanical/hydraulic engineers in general. I have yet to see a mechanical/hydraulic part with a transfer function or differential equation stamped on or included the accompanying documentation. Most of the parts that we use are 'evolved' or kludged and sold without transfer functions or differential equations. The companies that do real design like Caterpillar, and similar companies, test each part to find these transfer functions or differential equations. I know this because I have been to a IFPE show and attended a seminar given by a Caterpillar engineer. I have seen the lengths at which they will go to find out how a component really works to the point that I swear they know more than the manufacturer about the products they test. The testing of each component will take more time than the initial design, however, the initial design will provide an idea about what components are necessary or most critical. The testing of each component will use a technique called system identification. http://en.wikipedia.org/wiki/System_identification System identification is the first step in any auto tuning system in a motion controller. This is necessary because hydraulic and mechanical designers can't provide a system gain, a natural frequency and damping factor so this data must be generated empirically. So how much energy can be store in an accumulator? Start here http://hyperphysics.phy-astr.gsu.edu/hbase/HFrame.html Mary Gannon started this thread to stir things up. This is what I call a hit and run thread because she never intended to answer any of your questions. I will stir things up more by sticking a finger in your eye. Opinions are like..... and that is all I have seen. Show me math and physics. So here is a question for you all. If the accumulator is pre-charged to 10000 kPa or about 1450 psi. How big must it be to stop a hybrid vehicle weighing 4000 lb and moving at 60 mph. Opinions don't count. Accurate calculations do. Once we have the accumulator size then hopefully a Parker or Bosch Rexroth person will tell us how much that size of accumulator weighs.

Hi tcmtech,

It seems we are on the same wavelength about this, and
I wonder if we could work together; or could I maybe offer
some thing (cash?) for you to spec. a simple but workable
system for me please?

To over spec. it (a little) say, we allow for 1000kg vehicle,
(which would blanket most UK cars and small vans) and
allow a top speed of 100 mph, with approx. 0-60 in say >8 secs.
i.e. spec. isn't great; but would be acceptable to the majority.

The system should require the minimum quantity of oil, and oil
storage, (consistent with heat and longevity) due to weight, etc.
and as you rightly say use "off the shelf" parts where possible.

I believe 4 wheel drive is essential; for marketing, safety, etc.
with individual motors to each wheel to avoid drive trains; and
perhaps, a 2 into 4 wheel drive, change lever? (for economy?)
i.e.when it's sunny, down the motorway, or in town 2WD is ok.
Should the motors be chassis mounted with their drive shaft to
the wheel? (not wheel mounted to avoid various wheel effects.)

From your write in you think 60hp would be sufficient? (this seems
a bit low to me?) - but you know best on the system. i.e. if a few
more hp was available for very little additional cost it would be good.

My prime mover is as yet unsorted.
I am trying to "design" a direct displacement "engine" (as against driving
an off the shelf pump) which will hopefully provide approx. 6000 lb/sq in
pressure from the piston, and then arrange the displacement per second
output to suite the needs of the (your) system. eeeekkkk!
(to put it more simply, - I'm guessing at the present time!)

I look forward to your reply tcmtech.

jt.

I am not so sure about that. I get regular interest from many others locally and over the internet wanting my help in developing their ideas into real workable designs. That is typically they are wanting me to do the design, development, refining, financing, and marketing while they just wait to get a hefty kick back from what becomes of my work. They have no real solid concept of their designs and typically no money to work with in the first place. I am not going to spend tens of thousands of dollars I dont have just to bring someone elses million dollar ideas to life only to get thousands back for my efforts.

I am delighted to get the interest but yet typically disapointed by the people who are interested. Don't take this as being rude or uncaring but simply I have not found a single person who was interested that actually had any idea of what they would need in terms of money and resources to bring their ideas to the market. If you do have the finical and marketing resources available to push something like this though to a finished product I am happy to sign contracts and work deals for percentages of manufactured items market value. But still I wont hold my breath. No one has yet offered me any realistic pay rates or anything else with any serious intentions of actually doing anything let alone something specific.

It apears you have yet to even figure out what size of vehicle or exact target market you are after. Let alone the engine that drives it. I am by no means a manufacturing or marketing expert but I would guess that to even get a basic working prototype built would still be in the $1 million plus range and probably far more than that before its actually into the public sales markets. The materials are not the overall cost. The legality's, certifications, and general paper work needed to be able to sell it will eat up the largest part of the budget.

I am happy to help refine daydreams but unfortunately other peoples day dreams don't pay my bills well enough. Sorry to be blunt or sound rude, Its just that this is not my first day in reality. I like the ideas others have but still at this time I only focus my full efforts into my ideas and day dreams. At least I know what I am getting out of them and where I stand to gain or loose.

Thank you for your honest - and very valid reply tcmtech.

I have to agree it's a bit late in the day for me. However,
any journey, no matter how long, starts with the first step.
The critical question, first, is do I wish to go there?

It was thought of by myself in the 80's - and Delorian had
(believe) over 80 million in gov. grants, - which killed my start up.

There may be other opportunities. The UK car plant was "sold"
for £10 (ten pounds!) and has now closed with the 4 directors
considerably richer. LDV (light vans) is up for grabs - which I
think could be an excellent set-up for this project. ... Dreams.

Do I have the financial means? No personally, I'm not a millionaire.
Could I put it all together? With determination, yes, I think I could.
But it's far easier to dream. Action sorts the men from the boys.
Unfortunately action isn't readily available or easy at 70.

I am not put off by high costings, they appeal to the men with money.
Paper waste would get a severe chop from me - but give unto Ceasar...
Also simply, where there's a will... there's a way. I am, I can, I will.

What does undermine me is the need.. the world is drowned in vehicles
- and in very low cost production... Tata...Hyundai.... jt....?
What insanity would possess me to start making more? Do I want to
struggle with such a project at this time of my life? Enough defeatism!

I'll ask about the state of play with LDV. If my stamina holds out......
Who knows what might happen. The world's now. Let's play while we can.

jt.