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.  

The recip piston, Otto cycle, internal combustion engine is improving at a rate much faster than its proposed rival, the fuel cell. And there are still many significant improvements coming.

The main areas I see for future improvements in the Otto cycle piston engine are variable compression, variable displacement, various schemes for optimizing piston motion, and waste heat recovery through turbo-compounding (electric assist) or other techniques.  There are also some improvements that can be had with real-time feedback provided by in-cylinder combustion sensors.

I used to work with this old German engineer, who would respond to predictions of the demise of the internal combustion engine with the following: 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?

We are pulling at semantics classifying a turbine engine in the same category as the Otto cycle piston and valve engine.  As good as the turbine engine is, it really shines in constant load applications, far superior to the piston engine, but it cannot compare to the piston engine for throttle response and manufacturing costs, necessary for daily driving and private operation.  Toss in the efficiency of the turbine compared to the versatility of the piston engine and we have a real discussion.

The conventional piston and valve(/butterfly valve) engine has made significant advancements over its century plus life, certainly nothing to sneeze at, but most of the major advancements have been made in the last 20 years when electronics took a major role in design and controls.  Recognizing the items "tbuelna" lists, these are still refinements of the original design, basically correcting and improving on a design that originates almost 150 years ago.

Where do we go from here?  In my lifetime, or at the end of it, I too will be taken to my grave in a hearse powered by an Otto cycle engine, most likely.

The fuel cell will increase in popularity, but there is going to be a point where increased production will not significantly lower the cost per kilowatt, and we will need more power to make a transference of dominance between the piston and fuel cell powerplant.

MORE NEWS