Hydraulic Hybrids revisited

[user removed]

Hub diameters in the 4 to 6 inch range ID, absolutely.

If you position the journal so the pressure opposes the wieght of the vehicle bearing down on the hub, you will actually reduce the friction in the wheel bearings. The bearings themsleves are lubricated by the pressurised hydraulic fluid, so they are minatenance free, pressure lubricated and the same fluid is air cooled in the rotating drum.

Also sealed from the environment and completely submersible, without affecting the function.

I draw pictures in my brain and think myself to sleep at night. Been doing that with this project for almost a decade.

regards
Mech

[user removed]

Lets take a ride in a hydraulic hybrid.

Outside the car is fairly conventional, a balance of aerodynamics and practicality. No exotic materials mostly conventional body construction with attention to aero detail and low RR tires.

CD should be in the low 20s to high teens. No need for large grille openings with a smooth underside since their is no need for a power train.

The first two things that are obvious are that there is no gear shifter and only two pedals which are gimballed, meaning when you push one down the other goes up the same amount. The transmission tunnel holds the accumulator. The low pressure reservoir is the front cross member.

When you turn the ignition on there is no noise just an indicator to show you you are ready to go. The engine would only start if your accumulator pressure level was below the minimum level. The operation cycle of the engine is totally dependent on the pressure levels of the accumulator with a full throttle application creating a more aggressive engine cycle.

For reverse you will need to push a button. There is a interlock that prevents you from going backwards, because the two pedals are forward and reverse-regenerate. Without the interlock if you kept pushing on the left pedal you would stop, then start going backwards. The button prevents reverse without activation.

Pressing the right pedal control your rate of acceleration. At lower rates the hydraulic pressure is delivered from the accumulator to the wheels. At higher rates the pressure is supplied by both the engine and the accumulator. Climbing steep grades for considerable distances would deplete the accumulator pressure which would mean the power would come directly from the engine in the case where the grade exceeded the accumulator reserve.

The engine itself would be fairly large displacement. For a 2100 pound vehicle the engine would be about 2 liters displacement (if conventional). It would have no throttle control and run in the range of 1200 to 2400 RPM. If sustained grades were encountered that required more power to maintain higher speeds, a supercharger would engage to provide additional power. Engine RPM would never exceed 3500 RPM.

In normal lower speed stop and go traffic the engine would only run about 15% of the time. Duty cycle would be dependent on average power demands with 60 MPH level speeds requiring engine running about 25% of the time the vehicle is moving. Any deceleration or downhill operation would produce regeneration and additional accumulator pressure. If accumulator maximum pressure was achieved while still going downhill then restrictors in the hydraulic circuits would create drag. If you lived in mountainous areas the vehicle could use larger capacity accumulators to better recover regeneration forces.

With fully charged accumulators and supplemental engine power maximum acceleration would be only a matter of sizing the wheel motors to provide maximum torque to each wheel, up to the point where the tires would loose traction. Each wheel would have individual controls for traction control and anti lock brakes, with the typical sensors controlling the stroke position of each wheel motor to maintain traction when accelerating or braking. Normal energy losses in activation of traction control or abs systems, that use brake application or pressure interruptions to maintain traction would be accomplished by changing the stroke position of each wheel motor to provide maximum traction whether accelerating or braking (regenerating).

Each wheel motor would be an independent power application unit, requiring no interconnection of the wheels other than the sensors and control unit to determine actual vehicle speeds.

Accessory systems would be all electric, including heat and air conditioning. This is because the engine itself would be operating only a small percentage of the time the vehicle was operating. In some cases there may be enough surplus heat from engine operation to provide some heat energy to the climate control system. All accessories would be plug and play, without the complexity of belts and hoses of typical ac and heating systems.

A larger battery would permit extended operation of accessory systems when engine operation cycles were very low. Generation of electricity would only occur when the engine was running, by an integral starter generator incorporated into the engines flywheel, similar to the Honda Insight, but not used as a power supplement to the engine or hydraulic accumulator.

regards
Mech

[bbraden]

What about if you used a motor exactly like your wheels motors to run the accesories such as alternator, AC, power steering pump/vacuum pump? This way it could run when needed (say controlled by the voltmeter or A/C switch) so that you could also have peak efficiency of those parts also. You wouldn't have to have an A/C clutches this way and it would only use the exact amount of power it would need. They could even be direct coupled this way with the variable speed hydraulic motor.

I love your idea... but I have a few suggestions like this that I think will make it better.

Instead of a normal engine like you're talking about, what about a free piston engine? One with combustion on one side and hydraulic fluid on the other to provide a pumping action. Known for their efficiency capabilities, it could run on any fuel.

[gone-ot]

...although hydraulic DOES convey more torque/power, I'd prefer pneumatic because AIR is free (at least EPA hasn't taxed it yet) and a leak is neither costly (except for hose repair/replacement) nor possibly flammable.

...it's just a question of "how much" UMPH is needed that separates them.

[user removed]

Originally Posted by bbraden

What about if you used a motor exactly like your wheels motors to run the accesories such as alternator, AC, power steering pump/vacuum pump? This way it could run when needed (say controlled by the voltmeter or A/C switch) so that you could also have peak efficiency of those parts also. You wouldn't have to have an A/C clutches this way and it would only use the exact amount of power it would need. They could even be direct coupled this way with the variable speed hydraulic motor.

I love your idea... but I have a few suggestions like this that I think will make it better.

Instead of a normal engine like you're talking about, what about a free piston engine? One with combustion on one side and hydraulic fluid on the other to provide a pumping action. Known for their efficiency capabilities, it could run on any fuel.

No AC clutches. The ac unit would be more like a household window unit that was plug and play. A self contained mini window unit that would be capable of keeping you cool in a two hour traffic jam where you may only move a couple of miles.

As far as a free piston engine that directly generated hydraulic pressure I agree with you completely. Once you have an operational vehicle platform, where the engine is the pressure generation component, then you can simply change the engine and directly compare the overall efficiency.

This way there are no emission control considerations. I am not saying the free piston engine, or any other non standard configuration would not be an evolutionary improvement, just more of a "get her done" attitude that would produce a working vehicle. A gasoline engine at 35% or a diesel at 42% would be easily superseded by a 55% efficient free piston engine.

Argonne labs is working on designs for engines with a goal of 60% energy conversion efficiency. I think the direct hydraulic free piston configuration (suggested by EPA at least 5 years ago) will be a definite contender. If the gas version will average 80 MPG, the diesel should do 100 and the free piston would come close to 130. That is exactly what Ingo Valentin claimed for his hydraulic hybrid over a decade ago.

regards
Mech

[user removed]

Originally Posted by Old Tele man

...although hydraulic DOES convey more torque/power, I'd prefer pneumatic because AIR is free (at least EPA hasn't taxed it yet) and a leak is neither costly (except for hose repair/replacement) nor possibly flammable.

...it's just a question of "how much" UMPH is needed that separates them.

I like the idea of compressed air, the problem is auto detonation when pressures exceed 500 PSI in the presence of any kind of combustible lubricant.

Of course that would not apply to Nitrogen, or any other inert gas, that would actually be an on board fire extinguisher.

I believe the hydraulic option would be necessary for a normal sized passenger vehicle. It may be possible to use tap water, or at least distilled water for your hydraulic fluid, which addresses any leak issues.

I like the compressed air option for very lightweight vehicles where weight is a prime issue, and a liquid drive for heavier vehicles that would be more like what we drive today.

Neither of those opinions are fixed in stone and my opinion would change when I could see direct comparisons of efficiency between both designs. The "spring" effect in compressed air concerns me as far as overall efficiency is concerned and efficiency must be comparable to a conventional transmission for the system to provide the true potential benefit.

Taking a small weekend trip, will be back tomorrow evening to check this thread.

Good points my friends.

regards
Mech

[bbraden]

I like the water idea, a person would just have to make sure nothing began to grow in the system. You might could take water vapor from the engine in order to replenish any water losses if you had an exhaust condensation system. If you ran your free piston engine on hydrogen, you would have pure water come out of the exhaust.

This hybrid system could actually make hydrogen engines more feasible because of the improved overall efficiency.

[jamesqf]

[QUOTE=Old Mechanic;135596]No need for large grille openings with a smooth underside since their is no need for a power train.[\QUOTE]

Huh? Without a power train, it's not a hybrid. You're not going to manage to store enough energy hydraulically to even match a typical BEV range.

The first two things that are obvious are that there is no gear shifter and only two pedals which are gimballed, meaning when you push one down the other goes up the same amount.

Another thing you might want to think about. User interface design: you don't want your car's controls working differently than what is standard, so users have to learn to drive all over again. Look at the problems Toyota had just from replacing the standard ignition switch with a pushbutton, for instance, or what happens if you try putting me behind the wheel of an automatic :-)

[user removed]

[QUOTE=jamesqf;135682]

Originally Posted by Old Mechanic

No need for large grille openings with a smooth underside since their is no need for a power train.[\QUOTE]

Huh? Without a power train, it's not a hybrid. You're not going to manage to store enough energy hydraulically to even match a typical BEV range.
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Neither is a BEV, but who cares what terminology you choose to define it as long as it works. A HH would have two sources of power, accumulator and engine-motor so it falls into the definition of a hybrid, while a pure battery electric vehicle does not. Is that any reason to reject any configuration?
The criteria should be efficiency, not description.

James, this statement demonstrates the current attitude towards hydraulic hybrids versus BEVs.

Its sad that the BEV advocates want the HH advocates to play by their rulebook. In fact it may be that a combination of both technologies are the key to the success of the BEV itself (new rule book). The energy absorbed in regeneration can not be stored in the battery quickly enough. The return efficiency of a BEV would be in the range of 30% wheel to wheel. HH systems are shooting for over 80% and 85% is possible (currently high 70s).

It's also understood that even BEVs will need some form of transmission to improve efficiency and reduce the size of the primary electric motor drive as well as cost of the motor itself.

If you look at those facts objectively then you should be able to see that a smaller primary electric motor with some form of "gearing" will be necessary for a practical BEV. Also consider the HH eliminates the primary brake system, something not possible with any BEV. Trade the weight of the brakes the HH no longer needs for the in wheel drives and you only need an accumulators weight difference to have the HH configuration. Loose all the other no longer necessary power train components and the net weight loss would allow you to have a larger battery in a lighter vehicle.

You could use in wheel motors for the BEV, but they would weigh much more than in wheel HH IVTs.

Then combine that with the massive increase in regeneration efficiency and the ability to pulse and glide storage and the HH-BEV combination may actually be the pathway to success of any BEV vehicle. It sure seems like a smarter pathway than just sitting here waiting for the battery breakthrough technology to make it possible to have a practical 300+ mile range from a BEV.

The HH powertain platform also has the advantage of being easily convertible from IC power generation fro accumulator replenishment to BEV accumulator replenishment, using exchangeable power modules instead of the either-or complete vehicle option the is presently considered.

Not many people will fork over 25k+ for a range of 100 miles. Try putting just enough gas in your tank to have a 100 miles range. Then if you refill that tank you have to wait 6 hours to drive again. Even with quick charges it still does not seem very practical to me.
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Another thing you might want to think about. User interface design: you don't want your car's controls working differently than what is standard, so users have to learn to drive all over again. Look at the problems Toyota had just from replacing the standard ignition switch with a pushbutton, for instance, or what happens if you try putting me behind the wheel of an automatic :-)

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I think the go and slow gimballed pedals will actually be easier to work with than conventional systems. It is very similar to the current two pedal AT configuration.

Now as far as any individuals abilities with an AT vehicle, it is by a huge margin the most common system in operation today. Used every day by overstressed soccer moms, with 3 kids in the back, a cell phone in the ear, and numerous other possible distractions. No way you will ever get them to shift gears, that would be a disaster.

Personally I drive automatics with my right foot on the gas and my left foot just above the brake pedal. Not a recommended procedure, but for me it works fine and I have avoided some serious potential collisions by having that extra split second of reaction time. I am already driving that way.

regards
Mech

[Ruckus]

I am building a hydraulic hybrid. Check it out.
HI-MPG Commuter Car Build.. (back to the 70's) - Page 7 - Hydraulic Innovations

I found patents on hydraulic drive systems going back to the 1880's.
I highly recommend using Google patent search.
Google Patents

I am sure you are aware of the Vincent Carman hydraulic hybrid patents?

here is a link to a Mechanics Illustrated article everyone seems to have forgotten about that I posted:
HI-MPG Commuter Car Build.. (back to the 70's) - Page 2 - Hydraulic Innovations

I too started out thinking wheel motors. But there are issues. Mostly in terms of finding parts already in production that will work.
Here is the issue:
If you size the motors large enough for low-end starting torque, then they gobble HUGE gpm on the highway.
So a variable wheel motor is needed. The manufacturers COULD make such a thing, they just don't -yet.

Because of this I went to a single variable motor driving the rear diff.

one or four motors is not the important part. The regen circuit I designed is the part I am testing. My goal was total simplicity, as the hydraulic patents out there are overly complex.

By this summer I should have a working prototype. I am not sure if I will go the patent route, but it is a possibility since the design is so simple it is novel.

Cheers.