Chrysler battery-less hybrids announced

It's actually very easy - it's a bottle-like device called a nitrogen accumulator. Usually they are used to mitigate shock loading on hydraulic systems.

There's a rolling bladder inside a single-ported tank and when you pump in hydraulic fluid in one end, it compresses inert nitrogen in the other end of the bottle. It squirts the fluid back out if you take your thumb off the end.

Interesting uses: Intamin (Swiss roller-coaster manufacturer) uses them to launch trains on some of their rides - small pump builds up pressure in a bank of nitrogen accumulators, then uses that pressure to squirt the oil back out to drive hydraulic motors that spin a huge cable winch.

UPS has a prototype hydraulic-hybrid truck out there. Basically you just have to size the system to get "one shot" worth of storage - ie, deceleration from 60 mph... simpke. I think it was either Citroen or Renault that built a hydrostatic transmission into a car but decided it was too noisy and lossy to be efficient enough. But for a "hybrid" (ie, energy capture/re-use) it would be OK, since it's better than nothing (Friction brakes).

-Iain

 

Seems to be using the EPA's patent. Also this is a concept, no production plans at all...

Chrylser Joins Uncle Sam Building a Hydraulic Hybrid | Autopia | Wired.com

 

I know nothing about this subject apart from the fact that cars running on compressed air already exist (obviously not massed produced though)...no link but I think I read it on Wikipedia.

 

Ooh and that there is "mild hybrid" technology which stores regen energy in flywheels. I know that Porsche uses this technology (from Formula 1 car racing).

 

Hi All,

Tony P has the Tribune article on the Chicago Hybrid Group website. It details the Detroit region EPA office guy's 80 mpg (old EPA) hydraulic hybrid work.

Apparently, to avoid heat loss in the compressed gas accumulator, its filled with foam rubber pellets that slows down the tranfer of heat within the gases, to the sidewall of the accumulator. But, yea, overnight in the winter, there is going to be lots of lost charge. They might use the exhaust energy to heat up the accumululator. And then once emptied of pressure, run cold air over it, and then recharge it.

 

I heard about the flywheels but assume that as they spin faster they could severely mess up handling?

This system seems like a good idea. Gets away from the price of batteries. You lose the ability to have belt-less systems and shut the engine off (they say in the article they will but it would likely be like Honda without AC on!), but in addition to likely lower cost I bet this would also let you regen quicker than a battery (has a peak charge rate and kicks in friction if you exceed a mild braking rate) and pull from it quicker when accelerating.

I'm surprised, given how many decades regen braking has been conceived of and even prototyped, that we're really in such infancy in consumer cars.

 

:madgrin:
Oil doesn't compress ... leave it to chrysler to try to do the impossible. Air I could understand. Next they'll try to make 'em run on toxins that exhaust as pure oxygen. Joking aside, what the article is trying to say (but apparently the journalist ... using that term liberally ) ... they're trying to say that the ride runs on compressed nitrogen ... similar to compressed air, which is not a new idea. There are some 100% compressed gas vehicles running around the landscape in the EU now for over a year. But heck ... if you can add an ICE into the equasion, that'll keep all the mechanics in business, and the EPA too.

 

Apparently many of you have never "met" a hydraulic pressure sustaining accummulator. In the simplest form the air filled "riser" pipe in your home water pipe system to prevent pipe hammering, hydraulic ram ("water goat";<)) when you suddenly shut off water flow somewhere in the house.

All modern day ABS's have a hydraulic accummulator (think capacitor for you electron types) usually using nitrogen as the compressable gas. Up until about 2000 every automatic transmission built had an accummulator integal to the ATF line pressure control system.

But yes, liquids can be, ARE, compressed, otherwise VC, Viscous Clutches, could not be made to work. Back years ago we used a match head in a coke bottle filled with water to prove water was/is compressable. The match head could be made to sink by using your thumb in the coke bottle neck to compress the water.

 

This ought to be good. I remember Apple used to sell a lot of liquid cooled Macs and many eventually sprayed the motherboard with fluid, destroying the computer. Chrysler doesn't have the greatest track record for reliability, so being an early adopter could be frightening.

 

It would be interesting to see if anyone combines all three (ICE, battery, hydraulics). hydro for low-speed and initial acceleration, battery for low-mid speed cruising, and the ICE for everything else. On the Prius MPG is the lowest when accelerating, and battery assist isn't used too much because it would wear out the battery fast; moving that role over to the hydraulics could potentially help with MPG a bit.

 

Sounds wicked expensive

 

Yes - the gyroscopic force will play havoc with the handling if you have a single flywheel, or have multiple flywheels spinning in the same direction along the same axial direction. I believe you can counteract the gyroscopic force with multiple flywheels spinning in opposite directions and/or changing the axial alignments.

It turns out that flywheels are a wonderful technology to store energy for non-moving objects (like a UPS for a building), but for automobiles, there are many obstacles. The small size means they need to spin at extreme rates of speed, requiring very expensive space-age materials that won't disintegrate. Friction is also not the friend of a flywheel at extreme spin rates -- you need to find a way to levitate it inside a near perfect vacuum -- and never ever ever allow it to touch the enclosure. Speaking of enclosures, you need a serious "bomb shelter" to protect one of those things due to the sheer amount of energy stored. If it were to shatter, it would be a tremendous explosion that must be contained. There are some companies that did some exhaustive research in the automotive application of flywheels about 15 years ago, but it never took off.

 

That isn't because the water compresses - you're compressing the small bubbles of air that are trapped in the pores of the match head that reduces its boyancy and makes it sink. The water is not compressed.

If you could compress the water the match-head would float when you compressed the water because its density would become greater than the match-head.

kevin

 

Okay, my thumb is in contact with only the water, if the water is NOT being compressed then just what level of magic is involved in having enough pressure at the surface of those air bubbles to compress them, and keep them compressed (as the match head sinks), to the level that the bouyancy of the matchhead is reduced...??

And just what do you think happens inside that fixed volume hermetically sealed VC assembly..? No question that the VC fluid is heated via the disk plate "stirring" but CANNOT expand in volume so isn't the only option is that it THICKENS...??

 

That sounds more like sloppy reporting than a Chrysler error. Hydraulic accumulators have been around for over 100 years. Hydraulic fluid is pumped into a pressure container that has either a bladder or piston separating it from a gas, usually nitrogen. It's the gas that is compressed.

By using a variable displacement pump/motor you can efficiently save and recover energy over a wade range of pressures.

That type of system is at it's best when there is already a hydraulic system in place and widely varying or intermittent loads. Think Garbage truck.

It would also be useful in frequent stop delivery trucks, UPS, USPS, etc. They would require the addition of a hydraulic system.

A big advantage hydraulic has over electric is that it is no big deal to efficiently store and recover energy at rates in excess of 100 hp, a task that is a really big problem for compact, lightweight, mobile electrical systems.

 

I think there may be some confusion in terminology; When we say water is incompressible we mean that when placed under pressure it does not change its volume, it can still be placed under pressure and everything in the water (or surrounding it) will be subjected to that pressure.

When you place your thumb on the top of the bottle you do indeed increase the pressure in the water and that in turn puts pressure on the small air bubbles in the match-head. The bubbles will get smaller under pressure and reduce the boyancy of the match-head so it sinks.

I'm not sure what you mean by 'VC' - do you mean a viscous coupling?

If the viscous coupling is completely full of liquid and there is no air space then if the liquid heats and expands the casing will swell to relieve the pressure. Have you seen engine blocks where the water has frozen, or coke cans put in the freezer - they will expand or rupture even if not all the liquid has frozen.

Now water is not completely incompressible but under 1 atmosphere of pressure it will only compress by ~46 parts per million. By contrast air (or any normal gas) will halve in volume.

kevin

 

VC first: There are 3 design aspects of which I am certain about VC's.

A) To delay the onset of coupling, coupling beyond (5-10%..?) the natural viscousity of the fluid formulation, a gas bubble of a specific size/volume is introduced into the hermetically sealed VC enclosure.

B) A viscous fluid is chosen, formulated, that has a HIGH rate of volume expansion with rising temperature.

C) The interleaved clutch disks, fluid, and gas bubble are contained within a hermetically sealed case that in no way could "expand" at a rate cognizant with the rise in the VC fluid volume with temperature.

Back to the coke bottle; Once the match head is submerged what is acting on the gas bubbles to keep them compressed if not the PRESSURE of the surrounding water...?

And how does one "convey" pressure through an "atmosphere" of water absent compression of the water itsself....?

 

I think there is indeed some confusion on the terminology here.. The water is merely acting as a medium for transmitting an outside compressive force to the air bubbles in the match head. The water itself does not change volume under pressure, I think the other guys are trying to say.

The VC introduces one more variable that is not present in the match-in-a-bottle-of-water setup-- Temperature. The temperature actually causes a phase change in the VC's fluid so some of it turns to gas (expands in volume).

Remember that PV=nRT only works for gas, not fluids.

 

One last try....

When the match head is floating the air bubbles are fully expanded. As you press down on the water volume how is that thumb pressure "conveyed" to the outside surfaces of the air bubbles....?

Magic...?

 

I'm still not sure of the question.

One important fact with hydrostatics is that a fluid will exert the same pressure everywhere (ignoring gravity).

So when you pressurize the water with your thumb the water then it presses against everything it is in contact with - the sides of the bottle, the match-head, the bubbles inside the match-head and of course your thumb. Of the items in this list most will be unaffected by the pressure except for the bubbles - they easily compress, reduce their volume and so affect the boyancy of the match-head.

kevin