The future of the engine as we know it 1

[franzh]

I normally run like crazy when someone asks me questions about a "new" engine, but when one of my directors asks me to evaluate a "new design" design, my knees shake. That happened this morning.

We have seen free pistons, opposed oscillating pistons, scotch yoke pistons, toroidal blocks, ball valves, sliding sleeves, and tons of other combinations. Strangely, or not so strangely, none of these has ever reached any significant success. The old, inefficient Otto cycle engine still hangs around. With the exception of sealing refinements and air-fuel metering, almost nothing has changed in 100+ years, not including OHC engines which is a refinement, or phased cams, also a refinement, or exhaust aftertreatments, which is not a refinement, but an attempt at fixing an engine inefficiency.

I wonder how long it will take before something else pops up and takes a reasonably strong stand against the tried and true engine design?

Lets look at the true IC engine replacement, not hybrids (although I feel that is where we are heading for the next 25 years). Turbines are nice but not practical for a number of reasons.

When we look at H2 as a potential fuel, it still uses the Otto cycle engine as a base, only the fuel has changed. Are we really gaining anything on the engineering side? I recognize the significant advantage on emissions, but fuel transport, storage, and infrastructure have still to be perfected.

Any ideas, fellow engineers?
Franz


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[SomptingGuy]

I thought one of the main reasons Wankel-engined vehicles do well in competitions is that nobody can agree a way to compare them with reciprocating engines in terms of capacity. And since racing bodies generally classify vehicles based on their swept volume, their choice of that definition for a Wankel engine dictates whether the vehicle is super-competitive or a dead loser.

Remember bike racing in the late eighties? Norton caned everyone when they played the Wankel card.

 

[globi5]

In this article BMW claims that their 'turobsteamer' concept regains more than 80% of the heat in exhaust gases.

http://paultan.org/archives/2005/12/11/bmw-turbosteamer/

Besides they also transfer some of the heat energy in the cooling system into mechanical energy.

If this indeed works as advertised the thermal efficiency of an engine is less important and mechanical efficiency, power to weight ratio play a more important role (which could make Wankel or gasoline engines compared to Diesel engines more attractive).

The swept volume of a Wankel is twice the chamber volume. If the Wankel was operated as a simple air pump it would displace twice the chamber volume. (I don't see why there's much disagreement about this, but I do understand that they try to limit the options in order to keep it competitive - if one has an engine that is far superior, the race is boring.)

 

[turbocohen]

One of the advantages of a wankel is its low octane requirement. Plenty of them race with 85 octane fuel. High octane fuels cost power and the generally lower btu per volume yeilds less mpg's.

Years ago GM damn nearly went to production of a large vehicle wankel but smog and poor efficiency at the time killed it.

 

[evelrod]

dalcazar, I can give you a couple of figures based on my memory only as I no longer have the records from the 80's.
I can also give you one current figure for my 1380cc Mini Cooper race car.

1594cc Lotus Cortina twincam ~165 hp at the wheels---race weight of 2060 lbs., car and driver---Riverside Int. Raceway lap times 2:05 long course and 1:39 short course (this car retired three lap records at RIR)--- 10 gallons of race fuel per hour...
Same car with 139hp at the wheels 2:09's and 1:42's same tracks and ~9 gallons per hour.

<500hp tube frame IMSA Pantera RIR long course 24 gallons per hour...sorry I don't remember the weight, but it was pretty light tube frame and fiberglass...it was not my car, I was the "fuel guy" in the crew and I just ran the 'dump cans'.

1380cc Austin Cooper @ 110.45 hp at the wheels, 1730 lbs. race weight car and driver.
Based on three two hour races at Willow springs from 2003 to 2005... 7.2 gallons of Sunoco 110 per hour.

My only experience with a rotary engined car was in 1973 at the FIA Six Hours of Mexico City race where we were pitted near a little yellow Mazda sedan from El Salvador...it was incredably loud and used fuel like a NASCAR stocker!!!

Rod

 

[the3car]

Great thread guys. I haven't read the whole thing..but here's my $0.02.

Has anyone talked about valving technology? What I'm thinking is that a variable electronically controlled valving scheme could drastically change how the IC engine operates and how we "humans" can use the power.

From my IC engines in college, the valving has always been based on a cam lobe, which has physical constraints that an electrically operating valve would not have. I know there has been some shots taken at electronic valves, but maybe the technology is not there yet. Can an almost instantaneous valve opening/closing event really change what we know about IC engines? I think so. So far all of our CFD analysis has been done on realatively slow opening and closing of the valves. The physics may not change, but the operating efficiency and overall power characteristics may very well change. Sorry if this leads to another thread.

I agree with the basic assumption that it will take a very distruptive technology to unseat the IC from popularity. But like quantum computing, it's just a matter of time, before binary computing goes by the wayside and quantum computing takes over. I may go to the grave in an IC engine hearst..but my son or grandson may not...

 

[GregLocock]

Already available, and I think, about to be put in a production car. Delphi make one system.

The trouble is that it only offers an incremental improvement in real life performance/economy, at a quite remarkable cost. I suspect that a conventional, somewhat larger, engine could match the electronic valvetrain engine for torque, max power, and economy, by using a cam optimised for part throttle economy, and using sheer volume to get the other performance measures. Well, we'll see.



Cheers

Greg Locock

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[turbocohen]

EVT has been around the block a few times and although it is useful for lab work it is not practical for the road yet. yet.
The armature motion control is but one issue that has been resolved but cost and risk/benefit is not attractive.. yet.

One of the main advantages is less pumping loss and reduced oil vaporizing from exposure to valve gear for lowered HC's. Yes the digitally calibrated actuation of inlet and exhaust with burping features are attractive but variable systems are damn near as good at a fraction of the cost and risk. When 42v ststems become commonplace then the cost will come down a bit but I still do not want to own the first few generations of vehicles with evt. I think it makes more economic sense to use an advanced diesel hybrid.

 

[globi5]

Electromagnetically controlled valves give one the complete freedom when what valve to open or close (which is a tremendous advantage). However, I have difficulties to believe that electromagnetically controlled valves can be faster than mechanically controlled valves.

I was briefly involved in a feasibility study of a powerful electromagnetically controlled fibre rewinder and it couldn't reach the switching speed of the mechanically controlled rewinder.

 

[BenDutro]

Formula 1 uses electro-hydraulic valve actuation systems and they exceed 20,000 RPM. Will that be sufficient?

No matter what how they're actuated, poppet valves are far from optimal. Coates' spherical rotary valves have been in development for the better part of a decade now but I haven't seen any promise of production yet.

Look at this design:

http://www.revetec.com/

in a tubocharged CI configuration this would be an intriguing powerplant.

 

[globi5]

Actually electro-hydraulic could be faster than electro magnetic actuation, since an electrical valve only needs to travel a very short distance and instead of electromagnets piezos can be used.
Still still I don't necessarily see why a hydraulic linkage should be faster than a solid mechanical linkage.

So far I've only read of F1 engines with traditional camshafts and poppet-valves on 'air-springs'. Which F1 engines run on electro-hydraulic valves? Do you have more information?

 

[GregLocock]

"Formula 1 uses electro-hydraulic valve actuation systems and they exceed 20,000 RPM. Will that be sufficient?"

Rubbish on two counts. First they use pneumatically sprung poppet valves driven by conventional camshafts, and secondly they do not exceed 20000 RPM by design.



Cheers

Greg Locock

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[BenDutro]

Forgive me; the gearbox, not the valvetrain is electro-hydraulic. I did however watch the telemetry readout spin above 20,000 RPM with my own eyes.

 

[GregLocock]

Which race? Which car? Schu was topping out at 19000 rpm in the early part of this year,

http://members.optusnet.com.au/greglocock/cepstrum.htm

and none of the teams, so far as I know, were claiming 20000. With the V8s this coming year they might see 21000, according to the rumour mill.





Cheers

Greg Locock

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[crysta1c1ear]

From the link on Greg's site:-

http://f1.tottoro.hu/2004/01_australia/19_qlf2_mschumacher.avi

not found! It's a shame really. If you still have the sound file, could you post it somewhere please Greg?

(From the FIA website, regarding Formula One 2008 regulations)

ARTICLE 5 : ENGINES
5.1 Engine specification :
5.1.1 Only 4-stroke engines with reciprocating pistons are permitted.
5.1.2 Engine capacity must not exceed 2400 cc.
5.1.3 Crankshaft rotational speed must not exceed 19,000rpm [This figure may be increased to 20,000rpm in
consultation with the competing teams].
5.1.4 Supercharging is forbidden.
5.1.5 All engines must have 8 cylinders arranged in a 90º “V” configuration and the normal section of each
cylinder must be circular.
5.1.6 Engines must have two inlet and two exhaust valves per cylinder.
Only reciprocating poppet valves are permitted.
The sealing interface between the moving valve component and the stationary engine component must be
circular.

 

[GregLocock]

Hmm, that was 2 computers ago. I'll have a look.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Cheesy]

I attended a tribology conference last year and one of the presentations was on using a liquid who’s viscosity could be greatly changed in the presence of a magnetic field. This was used in a type of hydraulic lifter so effectively the valve lift could be reduced, the maximum lift was governed by the cam.

 

[Cheesy]

It might not belong here, but here is another 'new' engine concept that some of you may be interested in

http://www.pivotalengine.com

I dont think I have seen it on here before but sorry if its a re-post

 

[schwee]

I'm not sure I understand how this engine has advantages over existing clean-burning two-strokes incorporating direct in-cylinder injection. I can see the argument for eliminating piston rocking, but it seems there are sharp, square corners that need to be sealed. I think that's one of the reasons a rotary has problems with both wear and fuel/oil consumption. The engine also still uses the crankcase for pressurization-- a sure loser, in my book.

On the claim of "additional savings from not having oil changes factored in"-- does this mean oil is put in the fuel?

Then, any site that talks about hydrogen as a viable fuel source and doesn't know how to use the possessive "its" immediately raises my suspicions.

 

[MKimagin]

The Bourke Engine look like better (much simpler) solution then pivotal engine. In the bourke engine piston do not rocking, oil is totally separated, it is 2 struck so it guaranty high power density.

 

[Cheesy]

Also with the pivotal engine the 'active' cooling of the piston must reduce the engines efficiency, while the combustion chamber shape is also far from ideal. I like how the picture of the engine in a car does not show any of the other parts required to get significant power out of this engine such as the four rather large expansion chambers. In actuall fact this engine is very similar in size to a subaru engine