ChadInColo
Mechanical
Anyone here seen this engine design yet? Looks interesting, anyone have comments on it?
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Wiseman engine?
- Thread starter ChadInColo
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![[pipe]](/data/assets/smilies/pipe.gif "[pipe] [pipe]")
JayMaechtlen
Industrial
I think they will have to show a better test bed than a 30cc 2-stroke cycle engine!
Jay Maechtlen
Jay Maechtlen
Docengineheat
Mechanical
"A Complex Solution to a Non-Existent Problem" :-D
Very well said!!
At the very least, and even with a 30 cc engine, they should report what their power output is for comparison runs.
Very well said!!
At the very least, and even with a 30 cc engine, they should report what their power output is for comparison runs.
GregLocock
Automotive
There's something very wrong with their results.
CH2+1.5O2=CO2+H20
CH2+O2=CO+H20
Now, atmospheric air is about 20% O2, yet in their results the residual oxygen is virtually unchanged
Stock Wiseman hence deltaO2 used
CO 0.59% 0.77% -0.09%
CO2 4.70% 2.20% +2.50%
O2 8.20% 8.50% +0.30%
There should be much more oxygen left, only half as much has been used to make CO2, and the CO contribution is quite small. In theory the -0.09+2.5 should equal +0.30, which it obviously doesn't.
Incidentally both engines must be running rather lean, they are only using 60% of the available oxygen.
Cheers
Greg Locock
CH2+1.5O2=CO2+H20
CH2+O2=CO+H20
Now, atmospheric air is about 20% O2, yet in their results the residual oxygen is virtually unchanged
Stock Wiseman hence deltaO2 used
CO 0.59% 0.77% -0.09%
CO2 4.70% 2.20% +2.50%
O2 8.20% 8.50% +0.30%
There should be much more oxygen left, only half as much has been used to make CO2, and the CO contribution is quite small. In theory the -0.09+2.5 should equal +0.30, which it obviously doesn't.
Incidentally both engines must be running rather lean, they are only using 60% of the available oxygen.
Cheers
Greg Locock
Sure it looks like a neat little design, but not overly practical in my opinion. Seems like you're trading one set of problems for another. The performance of very small scale engines does not really concern me. There are a whole host of designs that work well in the miniature, but fail to cut the mustard when scaled up to passenger vehicle size. Rotating cylinder bores with integrated valves is one example that springs to mind.
I always find it strange that inventors seem to try and solve the IC engine's more trivial issues. Wonder why these people don't invent an engine that doesn't waste over 2/3 of the fuel's chemical energy heating up coolant.![[wink]](/data/assets/smilies/wink.gif "[wink] [wink]")
Regards
Bryan Carter
I always find it strange that inventors seem to try and solve the IC engine's more trivial issues. Wonder why these people don't invent an engine that doesn't waste over 2/3 of the fuel's chemical energy heating up coolant.
Regards
Bryan Carter
Sorry guys but I think this is genuinely very clever! Basically it allows pefect sinusoidal motion of the piston, for no additional package space and negligeable parts count increase. OK there's the usual techno mumbo jumbo that seems to be the normal sales pitch now. The real advantage, not mentioned, is engine life and balance.
Basically this design would allow a 3-cyl or 4-cyl to run with the same perfect balance as a straight 6. Yes I would buy a car if this was it's only selling feature! Ever done a long trip in a 4-cyl? Bloody horrible. Besides I would never need to worry about needing to rebore it, piston seizure and any other number of con-rod type problems.
Of all novel "big end" solutions I have seen this is the most practical...
Mart
Basically this design would allow a 3-cyl or 4-cyl to run with the same perfect balance as a straight 6. Yes I would buy a car if this was it's only selling feature! Ever done a long trip in a 4-cyl? Bloody horrible. Besides I would never need to worry about needing to rebore it, piston seizure and any other number of con-rod type problems.
Of all novel "big end" solutions I have seen this is the most practical...
Mart
Graviman, I would like to agree with you, BUT:
If I understand this correctly, the engine allows the elimination of rod articulation (done with a skirt, or piston-rod guide in tall engines like some Cummins diesels, to keep the piston aligned with the bore, and two pressure-lubricated journals)...
... at the cost of two sets of gears (which have to be precision-ground and hobbed) plus several other pieces, including what I believe to be one of the mothers of all tunnel-crank bearings. On the 30cc prototype engine this appears to have what patent drawings charitably call a 'plurality' of balls ... and the journal size is so large that I suspect conventional pressure lubrication of a journal would require a very, very large oil pump to supply once bearing clearances increased for any reason...
I don't see that the theoretical thermodynamic increases provided by matching the combustion-gas expansion with the mechanical advantage on the 'crank' are going to compensate for the higher fabrication costs involved. In any case, once you have modulated direct fuel injection in the cylinder most of this "advantage" goes away, as you modulate fuel-injection quantity and timing to produce whatever thrust profile at whatever piston position you want, within stoichiometric limits. Once we have electrohydraulic valve control (not far away) there is even less reason for complicated and necessarily precise big ends. And what happens with wear, insufficient lube or tribology problems, or thermal cycling of the engine? Seems to me that, in particular, ball and roller-bearing cranks have tended to fail miserably in automotive service wherever they have been tried, and have also tended to be difficult to service and maintain (Porsche fans, any arguments to the contrary? I'd like to be wrong on this...)
There is a definitive and effective answer to the 'problem' you mention with four-cylinder engines: balance shafts. Any remaining driveability problems probably involve something other than the inherent number of cylinders or firing order, perhaps involving attempts to operate the engine outside its powerband.
If I understand this correctly, the engine allows the elimination of rod articulation (done with a skirt, or piston-rod guide in tall engines like some Cummins diesels, to keep the piston aligned with the bore, and two pressure-lubricated journals)...
... at the cost of two sets of gears (which have to be precision-ground and hobbed) plus several other pieces, including what I believe to be one of the mothers of all tunnel-crank bearings. On the 30cc prototype engine this appears to have what patent drawings charitably call a 'plurality' of balls ... and the journal size is so large that I suspect conventional pressure lubrication of a journal would require a very, very large oil pump to supply once bearing clearances increased for any reason...
I don't see that the theoretical thermodynamic increases provided by matching the combustion-gas expansion with the mechanical advantage on the 'crank' are going to compensate for the higher fabrication costs involved. In any case, once you have modulated direct fuel injection in the cylinder most of this "advantage" goes away, as you modulate fuel-injection quantity and timing to produce whatever thrust profile at whatever piston position you want, within stoichiometric limits. Once we have electrohydraulic valve control (not far away) there is even less reason for complicated and necessarily precise big ends. And what happens with wear, insufficient lube or tribology problems, or thermal cycling of the engine? Seems to me that, in particular, ball and roller-bearing cranks have tended to fail miserably in automotive service wherever they have been tried, and have also tended to be difficult to service and maintain (Porsche fans, any arguments to the contrary? I'd like to be wrong on this...)
There is a definitive and effective answer to the 'problem' you mention with four-cylinder engines: balance shafts. Any remaining driveability problems probably involve something other than the inherent number of cylinders or firing order, perhaps involving attempts to operate the engine outside its powerband.
Thanks Wizlish,
I like a good technical discussion!
First off let me say that I agree with everything you have typed! Let me qualify my views on your response.
A 4-cyl engine would require quite a number of precision wound gears. I was trying to figure out yesterday how you would extend the crank to cover all 4 pistons. This would likely require additional planetary gears between cylinders 1/2 and 3/4, all designed for infinite fatigue life! Then again this is standard practice in modern rotary engines, with no drawback. I am still convinced that the entire friction across the whole assy would still be less than 4 piston skirts in there respective cylinders. The rover K-series used an offset crank, specifically to help reduce this friction. This concept even allows the use of linear piston bearings! Now that can't be bad.
With regard complexity, have you seen how complex the BMW valvetronic (mechanical) assy is?!? Agreed about simple valvetrain, although the loads will be lower. Solonoid valves will greatly affect efficiency, but I didn't feel this aspect of the design was actually worth commenting on. There are a lot of oddball systems out there, each claiming to have some kind of flow advantage. That's why we have CFD...
The main problem would be big end "chatter" although the right selection of oil would help with this - granted a good oil pump is a must. Gears can be precision hobbed very cheaply, but in hindsight perhaps a straight 3 or 4 is not the best application for this concept. I certainly like the idea of epicycloid mechanisms in 90 deg V-engines - very compact, especially if the flywheel mass can be designed into the crank assy.
The other advantage not mentioned is an increase in RPM, due to the removal of second order acceleration. Balancer shafts are still debated due to necessity of additional rotational inertia, and the package space required. This can be a real problem in some 4x4 applications.
OK maybe I went off half cocked with my post, but I just felt it slightly unfair that the merits of the concept were not being discussed. It is all too easy to shoot down a new idea, just because it doesn't fit in with the standard way of "doing things". I feel it is important to investigate all the pros and cons of a new idea. If it is not practical that will come out, and better that all feel that the decision has been reached for sound engineering reasons...
Mart
I like a good technical discussion!
First off let me say that I agree with everything you have typed! Let me qualify my views on your response.
A 4-cyl engine would require quite a number of precision wound gears. I was trying to figure out yesterday how you would extend the crank to cover all 4 pistons. This would likely require additional planetary gears between cylinders 1/2 and 3/4, all designed for infinite fatigue life! Then again this is standard practice in modern rotary engines, with no drawback. I am still convinced that the entire friction across the whole assy would still be less than 4 piston skirts in there respective cylinders. The rover K-series used an offset crank, specifically to help reduce this friction. This concept even allows the use of linear piston bearings! Now that can't be bad.
With regard complexity, have you seen how complex the BMW valvetronic (mechanical) assy is?!? Agreed about simple valvetrain, although the loads will be lower. Solonoid valves will greatly affect efficiency, but I didn't feel this aspect of the design was actually worth commenting on. There are a lot of oddball systems out there, each claiming to have some kind of flow advantage. That's why we have CFD...
The main problem would be big end "chatter" although the right selection of oil would help with this - granted a good oil pump is a must. Gears can be precision hobbed very cheaply, but in hindsight perhaps a straight 3 or 4 is not the best application for this concept. I certainly like the idea of epicycloid mechanisms in 90 deg V-engines - very compact, especially if the flywheel mass can be designed into the crank assy.
The other advantage not mentioned is an increase in RPM, due to the removal of second order acceleration. Balancer shafts are still debated due to necessity of additional rotational inertia, and the package space required. This can be a real problem in some 4x4 applications.
OK maybe I went off half cocked with my post, but I just felt it slightly unfair that the merits of the concept were not being discussed. It is all too easy to shoot down a new idea, just because it doesn't fit in with the standard way of "doing things". I feel it is important to investigate all the pros and cons of a new idea. If it is not practical that will come out, and better that all feel that the decision has been reached for sound engineering reasons...
Mart
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