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VCR engines - the next frontier

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  • VCR engines - the next frontier

    Due to all the engine talk lately I did want to bring something up in a separate post so not to intrude on Brians engine build O.P.

    We are living in a time where new engine idea's are dime a dozen, there is allot of rubbish to sort through - engines with no particular benefits yet a ton of pitfalls, but there's one thing im sure of and that's that Variable Compression Ratio IC engines are not a fad, they will be made very simply and be so practical with the power and efficiency benefits that they will be hard to ignore,,,

    Here is a little taste of some of the bennies, http://www.youtube.com/watch?v=DdM2VbbdtB4

    I have to add - this is nothing new - VCR's have been around for several decades - people knew even back then all the potential benefits but with all the electronic controls we have now comes unbelievable benefits that could never be realized before - changing ratio's "at the drop of a hat" can reap rewards throughout the range - it can keep volumetric efficiencies high AND power production AND optimized fuel burning AND therefor fuel consumption AND also reduce NOx emissions all at the same time...

    To show just how long this idea has been out SJ's post of the Armstrong engine looks like it has little eccentrics on the lower pivoting ends of the rocker links and im thinking that's exactly what they were used for - there's also a plethora of other examples old and new.



    But the point to all of this is the opposed piston engine offers a very simplistic solution beyond the complexities of many of example - and that is simply to split the crank and change the timing of the two crank throws in comparison to each other - furthermore - if there are intake or exhaust ports involved or if the crank halves are individually linked to intake and exhaust valve timing accordingly - the sky is virtually the limit as you can automatically incorporate VVT into the mix without any additional moving components --- the results would be a normally aspirated engine that could pull a stump out of the ground @ 1,500 RPMS and come on like an indy car at 10,000 RPMs +

    The problem with allot of these newer engine designs is they simply don't get it - reciprocating pistons do not "waste power" they give back what they take --- and due to bore and stroke can be tuned to suit a variety of things and are easily serviceable, but that being said - just like any other engine they are "locked in" to a predetermined CR, sure you can add things like turbo chargers and such but you cannot "spool up" in an instant - you can go supers chargers but have to pay the fiddler in HP robbing parasitic drag,

    With the invent of direct injection gas - turbo chargers make allot more sense - WHY? it's due to not having to run 7 to 1 compression ratio so they can now keep the thermal efficiencies up higher than before, but in comparison to VCR they are still crude cumbersome slow response devices...

    Imagine a direct injection gas engine that runs without any spark plugs - and adjusts it's compression ratio within milliseconds to suit whatever needs are thrown at it, all whilst keeping control of the burn rate with pulse controlled injection, the possibilities are endless...

    this is where we should be putting all our effort right now - mark my words this is the next biggest breakthrough - the mechanical's are nothing to create - we are already using hydraulic degree changing devises on most cars camshafts right now that are equipped with VVT... piece of cake... just one single beefy one for the two cranks to be linked too... that's your only added extra mechanical complexity...

  • #2
    When Brian started the current build several of the Armstrong style engines popped up including the VCR varieties (including that shown above). There is an article in the peer reviewed literature that discusses modern designs that incorporate OPOC and VCR features and yep - very interesting. The tend to have ported vs valved asperation and are supercharged two-stroke.

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    • #3
      " reciprocating pistons do not "waste power" they give back what they take" ?
      I can see where a piston can give back SOME. of the enregy that it took to compress the mixture and the valve springs might give back SOME of the energy it took to compress them . There is still a lot of energy consumed in stoping and starting the piston and rods and valves.An example would be spinning a turbine engine in a vacuum chamber and spinning a piston engine in a vacuum .Even if you had loose teflon coated pistons and no friction robbing rings ,the engine would coast to a stop in seconds wilst the turbine would coast for a many minutes.Edwin

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      • #4
        DP - we been putting the cart before the horse,
        Due to a fixed ratio we start at a deficit and then try to adjust with multitudes of patchwork after the fact - in the form of enriched mixtures and retarded spark and built in compromised valve timing,

        We should be introducing the most optimum compression ratio for any given load or RPM range and then running with the finer details afterwards...

        the opposed piston engine is one of the most simplex engine forms for a VCR to be incorporated into,,, it is interested, and I usually do not get stoked about engine designs anymore - but Brian's engine and the other examples made me ask "what if" when it comes to VCR's - but so far as iv seen nobody is altering the two crank journals timing,,,
        This would give you immense control - and if the segregated units are then individually linked to valve timing, one for intake and the other for exhaust, it could be a VVT "freebee"
        I don't believe anyone is thinking along these lines ... the possibilities are endless...

        It would have every potential to be the worlds highest HP per cubic inch normally aspirated engine ever in production - it could also prove to be the most efficient , and it could run on everything from gas to diesel to 1/3 bat urine...

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        • #5
          Originally posted by Edwin Dirnbeck View Post
          " reciprocating pistons do not "waste power" they give back what they take" ?
          I can see where a piston can give back SOME. of the enregy that it took to compress the mixture and the valve springs might give back SOME of the energy it took to compress them . There is still a lot of energy consumed in stoping and starting the piston and rods and valves.An example would be spinning a turbine engine in a vacuum chamber and spinning a piston engine in a vacuum .Even if you had loose teflon coated pistons and no friction robbing rings ,the engine would coast to a stop in seconds wilst the turbine would coast for a many minutes.Edwin

          All engines have to deal with friction --- the piston engine by design gives back every bit of reciprocating energies it consumes - minus the friction,,, It may take x amount of energies to get the piston moving from TDC to max feet per second close to half way down the bore, but after that every bit of that energy is being returned back to the crank - every single bit minus the bearing friction and such,,,
          I hear guys on here talking about the balance of their mills spindle at 6,000 rpms on here like they are going into the unknown,,, that's a totally round concentric part,,, now try upping the ante to 3 times that amount with connecting rods and pistons flailing about, Fact is - is the piston engine is very hard to beat, and it's actually a very good design for what it does...

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          • #6
            I remain skeptical. Some people believe what they are told, but I must be "Schoen". For all the many years of research and promises as presented in the YouTube video, it seems there has yet to be any publicly published hard figures for fuel economy or power/torque/RPM curves. The video seemed to be a cry for investors, and was not very convincing. Show me a car, put ten gallons of gas in it, and let me see it go 450 miles. Mine will, and it's a low end 1999 Saturn.

            Here are other references to the technology:
            http://en.wikipedia.org/wiki/Variable_compression_ratio
            http://www.nissan-global.com/EN/TECH...RVIEW/vcr.html
            http://www.docstoc.com/docs/16043065...e-using-Diesel (0.472 kg/kWh)
            http://www.saabnet.com/tsn/press/000318.html
            http://topics.sae.org/variable-compr...rs/automotive/

            According to the Wiki article a diesel engine running at its best "sweet spot" has a BSFC of 206 (40% efficiency).

            It is very possible to build a hybrid where a diesel engine runs at this "sweet spot" to charge batteries and/or supply mechanical and electrical power to high efficiency electric motors, and an electric vehicle is much more efficient than any other at very low speeds and consumes nothing when stopped in traffic. Perhaps a VCR engine can be more efficient at a wider range of conditions than its more conventional cousins, but that is because the overall efficiency of fossil fuel engines is so horrible that it takes very little "tweaking" to get the 30% increase as claimed. The cycle average for a gasoline engine is about 322 g/kWh, or 25%, and the best figure shown for the VCR engine is 472. So it appears to be much worse, actually!

            If you can find any other hard figures, please provide them. The low figure for the research report may have been because it was for a 5 HP engine, and there is probably a size factor when compared to automotive engines of 100+ HP.
            http://pauleschoen.com/pix/PM08_P76_P54.png
            Paul , P S Technology, Inc. and MrTibbs
            USA Maryland 21030

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            • #7
              I did just pull that video out of a hat, it is somewhat complex in design but I did like some of the details of the benefits, and they did say most of the correct things, and had a fair level of sophistication about sensor/input/results related topics...

              there really is no "smoke and mirrors" here - the science of thermal efficiencies being increased with higher compression ratio's is a proven fact, you just can't go around lugging an engine with high comp on cheap fuel and expect good results due to either having to retard the timing way back or have your engine die an early death of pre-ignition/detonation,,, it's also not good practice for emissions,

              also - along with variable compression ratio is effective compression ratio and volumetric efficiencies - anotherwords - you can take in a full intake charge even though your at a very high RPM, this equates directly to more HP... and due to the engine catching up to the flame front you can get away with quite high ratio's when it's rapping its guts out...

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              • #8
                I was just browsing around and found this - It's just a matter of time before someone really perfects these systems for automotive use,,, and they talk of getting it done the same way I mentioned yesterday;

                The architecture of the Pinnacle opposed piston engine is well suited to the addition of a VCR system. This may be done through the use of a phaser, similar to the ones used to adjust the timing of a camshaft in a VCT system. The phaser for a VCR system requires a higher torque capacity than the VCT system.

                There's also some in depth testing done by the FEV and the mention of incorporating VCR with valve or port timing,

                http://www.greencarcongress.com/2013...-20130515.html

                This is where it's at , Its creating engines that go after proven facts of increased thermal efficiencies, Not some guy building a pile of sophisticated crap that does not address any of these issues...

                First off - people need to get it through their heads that piston engines are not a big power waster - just because it reciprocates does not mean it's wasting energies, it gets back what it gives minus the friction,

                get off the rotary kick - in a total seal IC engine there are no true rotaries as they either have to oscillate or have smaller pivoting or reciprocating movements of some kind, and many are nowhere near as direct in power transmission, not where the answers lie.

                Right now the biggest thing to go after is VCR, and it can be done without being too complicated... It will open up a whole new way of engine management...

                Comment


                • #9
                  Perhaps I have spent too much time on the DIYelectricCar forum, and also perhaps my background as an electronics engineer with experience in motors, batteries, and power conversion, I am still "underwhelmed" by the VCR and VCT and other ICE technologies. The dinosaur has been dead for a long time, and the fossil fuels created in the millennia after its extinction are running low. We need to look at sustainable energy sources as well as ways to reduce our per capita use of energy, so that we can utilize petroleum for its other unique properties to make plastics and pharmaceuticals, rather than just burning it at 20% or even 40% efficiency for electric and mechanical power. The gasoline engine was developed during a time when petroleum was used primarily for heating oil and kerosene, and gasoline was a waste by-product. It was so cheap that even very simple and inefficient engines were practical, and there were not that many in use to cause pollution, global warming, or significant depletion of resources. But businessmen figured out how to market ever bigger, more powerful cars, and increased need for personal transportation with suburban sprawl, to generate huge profits.

                  Now we have reached the limits of an economy based on cheap energy from fossil fuels, and we are entering an era of inevitable downsizing and change to a lifestyle and aspirations much different from that of the '50s in the US. We have reached "Peak Oil" (as predicted by Admiral Hyman Rickover in 1957), and we must deal with the consequences intelligently and realistically. It is good to pursue new technology for ICE power sources, but we are approaching the theoretical limits of energy extraction and conversion to mechanical power. For many years the "holy grail" was the 100 MPG car, but that has now been achieved and surpassed. However, it is impossible to make a 100 MPG SUV or heavy truck capable of towing 6 tons over mountains at 70 MPH. There are physical principles that determine a vehicle's MPG, and to a large extent they determine the fuel economy much more than the efficiency of the power plant. I made a calculator which shows the power and energy required for a vehicle depending on weight, frontal surface area, rolling resistance, speed, and acceleration (or slope), and the results may be surprising, although they are well understood by those who have or make their own EVs:

                  http://enginuitysystems.com/EVCalculator.htm

                  The information given in the OP's link does not really show the relative efficiencies of the engines themselves, because the design of the car, along with driving techniques and the terrain covered, have far more effect on fuel economy. The figures given may seem impressive to someone who drives a gas-guzzling SUV or pickup truck, or who drives aggressively, but my reasonably sized car, driven conservatively, already averages 35 MPG and has achieved 46 MPG on a long trip. And it is not a tiny foreign car as seems to have been used for the testing.

                  Yes, keep working on new ICE designs, and maybe you can eke out a few percent greater efficiency, but the future belongs to electric cars, hybrids, vastly improved public transportation, railways instead of trucks, and a more efficient lifestyle with shared resources and greatly reduced need for daily commutes and traffic jams, as well as elimination of the resultant frustration, lost time, and road rage.
                  http://pauleschoen.com/pix/PM08_P76_P54.png
                  Paul , P S Technology, Inc. and MrTibbs
                  USA Maryland 21030

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                  • #10
                    Instead of trying to make the engine ultra flexible with VC , hasnt it been easier to achieve greater efficiencies with CVT which allows the engine to operate in a very narrow rev range.
                    I cant see engine makers wanting to mess around with the complexity of VC when they are simply trying to make money, imagine trying to get one repaired.

                    Paul , you are right about ev's etc being the next big thing, but we will wait till the very last minute before we jump that hurdle, countries outside the US have shown that petrol can cost a hell of a lot more before we stop buying it. We pay equivalent US$7.11 per US gallon and nobody is screaming about it.

                    Poeople will downsize their cars to get the economy , rather than invest in more complex mousetraps to get a small efficiency gain, then eventually go to ev, hydrogen, producer gas etc
                    My neighbours diary says I have boundary issues

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                    • #11
                      Put the effort into development of a free piston ICE for generating electricity.

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                      • #12
                        As long as we remain tied to the establishment for our transportation needs, we will be paying a high cost for it. As long as we prove that we are willing to keep paying this cost, we will be able to get alternate forms of transportation. It may be electric, it may be gasoline for the forseeable future- either way it will be expensive. Any means we use in a bid to decrease personal costs will eventually backfire as 'the powers that be' will strongly resist that in one way or another. I think it's likely that there will be taxes and fees impressed on those who are able, for instance, to supply their own power to recharge their electrics. In the case of the IC engine, we will be paying more for the fuel- which will just make it doubly expensive for those who don't have or can't afford the improved IC engine technology.

                        You can downsize your car, use a more efficient IC engine, make your own power to run your electric vehicle (and your home) but any large-scale disconnect from the burden of paying our 'suppliers' will be met with legislation etc designed to keep the money rolling in (and out of our pockets). No expense will be spared to keep this going, environmentally or otherwise. Until we can overcome this juggernaut, all these schemes to increase efficiency, etc will just be carrots on a stick.

                        I'm not against improving technology, but I don't see it ever resulting in cost decreases in general. We keep looking at it as if it will, and we are either deluding ourselves or being deluded. We are the cows, and our farmers (our owners) will use whatever means they have to in order to keep milking us.

                        We, as HSMers and like-minded, may be able to individually create savings and gains for ourselves, and I for one am certainly happy to be able to do that to some extent. If our group gets too large and starts to have some economic impact on the milkers, there's going to be an 'equalization' of sorts- you can bet on it. As I see it, that's the biggest hurdle to overcome, not the relative inefficiency of the IC engine.
                        I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                        • #13
                          Interesting thought, but if we truly believe in our democratic system and fully participate, we have the power to control the corporate interests that seek only profit without regard to long-term effects on people and the environment. I still believe in that system but I am dismayed at the lack of participation by the citizens who often do not vote, or who seem to lack the intelligence and education to identify lies and misrepresentations by political candidates in their desire to be elected. Many of them accept huge corporate "gifts" to finance dirty campaigns and devious tricks that delude people into believing their assertions and promises.

                          There have been some indications of excessive corporate practices and political pressure designed to discourage individual sustainable energy initiatives:
                          http://www.diyelectriccar.com/forums...lar-92031.html
                          http://pauleschoen.com/pix/PM08_P76_P54.png
                          Paul , P S Technology, Inc. and MrTibbs
                          USA Maryland 21030

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                          • #14
                            All good points but the closer you get the better off you and your wallet will be, for the most part it's the energy that will be taxed or when the supply can not keep up with the demands be priced higher and higher, as far as the vehicles themselves it may actually work in reverse as is what's going on today with tax breaks and such...

                            The fact is - is nothing is going to happen overnight, alternatives should be pursued to the fullest extent - but that also means alternatives for the masses of what we will be doing for some time to come - burning fossil fuel.

                            As far as VCR not being as applicable due to us creating CVT's that keep engines in one range - that is an extremely small percentage of vehicles but even they could benefit greatly just because it's not all "RPM" related, it's load related too, and having a VCR engine that "thinks ahead" and predicts and adjusts for the perfect compression ratio for optimum crank angle whilst the flame front going off is the way we should be utilizing this precious resource,

                            But instead every power stroke is a compromise due to a fixed compression ratio, therefor we either have to add a higher ratio of fuel for certain load and RPM's to keep the mix cool and from going off prematurely or retard the spark to the point of getting away from optimum crank angle,
                            If every power stroke is a compromise it is a direct effect on total efficiencies, We do have great computer control over all this stuff - but like I said earlier it's putting the cart before the horse,
                            we should be using this same bag of tricks but starting with the CR - then adjusting everything else to cover the finer details.

                            This is so important a fact that I see no other direction for things to go, we will inevitably be "going here" unless somebody comes out with an incredible breakthrough in another field...
                            Last edited by A.K. Boomer; 01-12-2014, 10:24 AM.

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                            • #15
                              This probably tells my age, but when I first saw the title, I was trying to figger out howinell you were going to make an internal combustion engine from a video cassette recorder...

                              Mark

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