Perhaps a technical sage could take a look at this site and tell us if they think it's as revolutionary as it appears.
P.
www.mayflowere3.com/index_flash.html
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Mayflower.
Personally not sure about those extra bits flailing about, but its definitely interesting.
Strongly prefer this idea though.
Lotus Engineering Active Valve Train & Active Combustion
www.lotuseng.com/template.cfm?name=lotengresnewtec...t
Means you can have the valves open at any time in the cycle, the only limiting factor is that the engine runs and they don't hit the pistons or each other.
Eg by appropriate timing of exhaust valve you can use internal EGR, ie not all the combustion gases are exhausted, so lowering temperatures and reducing NOx prodcution. But the exhaust gases are used to raise the temperature of the mixture so its a compression ignition engine.
I believe this technology can also be used to operate an All Fuel Engine capable of running various fuels/mixtures which have hitherto not been possible.
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PM,
I thought this was going to be about the engine of a Mayflower, we had one in Singapore in the 60s, BRIGHT yellow paintwork too!
Stu.
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I have taken just a brief look at this engine design and it seems to promise similar advantages to, for example, the Scotch Yoke conn rod designs that have been proposed in the past, i.e. better control of the motion and speed-change of the piston. The disadvantages that immediately spring to mind are manufacturing expense, assembly complexity, weight and packaging (engine size and shape).
Mayflower appears to be one of a huge number of 'variations on a theme' that regularly issue from hopeful inventors and keep the Patent Office in work but otherwise come to nothing. I expect that any major new and successful design will come from within the industry because that is where collective skills, knowledge and facilities are already in place.
Many new engine designs appear at first sight to be flawless and many are presented very cleverly, with convincing computer animations and strong arguments in support of them. However, after careful study, practically every one of them is sooner or later found to have a fundamental technical, manufacturing or commercial flaw and has to fall by the wayside.
It would be nice to see a new world-beating engine design, the last one I suppose being the Diesel engine patented as long ago as 1892 (and proposing coal dust as the fuel!). It would also be nice if Mayflower was this new world-beating engine for the sake of Dr Ehrlich and the huge effort and expense that he has obviously put into it. But I doubt it.
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Heavely advertised in the press over the last Year ,Ford are providing much of the backing but no success as yet.
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PM
The principle is still a standard IC engine, and I think the benefits quoted seem rather too good for the changes proposed. In particular I'm unsure how operating some of the time at lower compresion can give efficiency benefits. I also have doubts about things like engine balance (given all the extra components), cost, size and emissions performance (given the constant changes in CR).
We shall see, but vehicle history is littered with other 'revolutionary' engines which have simply failed to live up to the hype.
regards
Regards
John S
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I agree with everything that John has said. At the risk of boring the pants off Backroomers (again!) I'll relate the combustion/emissions scenario in a diesel engine, which the Mayflower concept is claimed to be suitable for.
In a modern direct-injection diesel engine, the combustion bowl will be in the crown of the piston and the shape will be carefully arrived at with the help of a complex process known as computational fluid dynamics (CFD). The shape will be crucial to the efficient mixing and initial combustion of the air/fuel mixture. The shape should promote, but also precisely control, the required swirl (smooth path) and turbulent (broken path) movement of the gases throughout the speed range of the engine to ensure ultimate mixing under all conditions. At the same time it should minimise gas flow against the wall of the bowl as gas/wall flow will increase thermal transfer via the piston to the cylinder block, hence useful energy will be lost into the cooling system. Another important point is that the fuel being injected must go deep and wide into the combustion bowl but must not touch the walls.
At TDC the combustion bowl will be almost gas-tight because the flat underface of the cylinder head will act as a cap over the combustion bowl. This helps minimise trapping of any fuel or air/fuel mixture in the lands between the piston and the head during the critical early stage of the injection/mixing process when the fuel is still in droplet form. Any fuel trapped in these lands, especially in the corners, is unlikely to be fully burned and will exit the engine as particulate emissions and will also increase the specific fuel consumption of the engine.
Bottom line: If the piston is pulled up short on its compression stroke, as in the Mayflower engine, these critical parameters of combustion and injection cannot be achieved.
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I seem to recall a thread on this sometime last year, Im sure I posted.
Bill
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I take it nobody wants to discuss that then.
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FiF,
I'll break the ice for you, but will try not to be as much of an 'anorak' as I have been recently!
As you may know, many engine firms have been working on what is known as 'unit valve operation' for a number of years, including hydraulic, electro-hydraulic and electro-magnetic, with or without spring biasing/assistance. Major problems, especially with electro-magnetic (E-M)operation, are;
1. High power is required to open and close the valve and hold it in those positions, bearing in mind that a camshaft system is not 'total-loss' because some of the energy taken to open a valve will be returned as the valve closes. That is, a closing valve is helping to open another further along.
2. The speed/ramp control of valve opening and closing is easy with a camshaft but not with unit valve operation.
3. The operating units can be cumbersome (especially E-M where the motive-power generation needs to be at the valve). On a 4-valve engine, it should be possible to drive two valves with a single unit but still not easy to find the room.
4. Springs may be needed to ensure that the valves are held against their seats at engine start up (and on failure of the system, so that the pistons and valves don't meet head-on). With at least one E-M system, two springs are used to assist movement, one each way, but any power failure will leave the valves sitting half-open, which is not ideal!
There is no doubt that unit valve operation will be with us soon. Combined with unit injection, the possibilities are endless (two-stroke under high load, six-stroke cruising, semi-random firing to change the acoustic signal from military engines [to avoid engine recognition from its sound], etc).
I have no specific comments on the Lotus system but wouldn't be surprised to see them at the forefront of unit valve operation in motor car engines at least, with perhaps other companies specialising in commercial vehicle, industrial and/or military engines.
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Another thought ...
BMW's Valvetronic engine is currently fitted to one of the BMW 3-Series and the new 7-Series, and is sure to be in the new 5-Series due next year. This is the engine that controls air intake into the cylinders by variable opening of the valves, rather than by the usual throttle intake butterfly, the result of which is exceptional economy and torque, and lots more.
Now imagine Valvetronic combined with Unit Valve Operation. That is bound to be with us soon and it will ensure that BMW engines remain the best in the world !!
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