This is far beyond the present state of the art. New design and material solutions will be necessary to handle this. Subscribers can view annotate, and download all of SAE's content. Learn More ». View Details. Browse Publications Technical Papers The cylinder pressure curve determined by means of cylinder pressure measurement is the most important source of information for cylinder pressure indication.
Cylinder pressure indication yields more accurate knowledge about the thermodynamic processes during combustion and the engine power that is delivered. The effects of actions to optimize the engine based on this knowledge are:. Cylinder pressure measurement is mostly performed with piezoelectric high-temperature pressure sensors that are installed through a mounting bore which has to be drilled in the cylinder head for this specific purpose.
Measuring spark plugs with an integrated high-temperature pressure sensor are also used. They do not require a mounting bore because they can easily be screwed in instead of a standard spark plug. On diesel engines, special glow plug adapters can also be used for the measurement. The measuring chain is completed with a charge amplifier, a data acquisition system and an evaluation system.
In the automotive sector, there are also innovative indication systems that combine data acquisition and evaluation in one device; these can be used on test stands and also as mobile applications.
Developers aim to obtain the highest possible proportion of mechanical work from the conversion process — in other words, their goal is to maximize efficiency. Significant factors here are the level and curve of the cylinder pressure over the crank angle, acting on the piston. This pressure curve represents the combustion, so it indicates how energy is being converted in the engine.
The total mechanical work on the piston summed during one combustion cycle or stroke is obtained from the pressure and the related change in volume of the combustion chamber.
The analytical solution comes out a bit higher, of course. I'm sure there are probably guys here that have real software at their disposal so perhaps they could give you more accurate numbers. And don't forget about RPM when considering rod strength, of course. I hope this helps.
I have measured over psi in a highly turbocharged 4 cylinder engine. That seems reasonable, though I would expect the engine to have a short life at that condition unless it happens to be highly developed for durability at that level of stress. Anyone have any experience with HCCI peak pressures? What I have seen is not out of line with the discussion above. Current production cylinder kits were used.
Plausible, and comparable to modern turbodiesel peak cylinder pressure. Regarding HCCI, nobody has much experience with those at all! From papers that I've seen, they seem to be developing these based on standard gasoline or diesel engines and the HCCI operating mode is only used at light load - not the condition that gives highest peak cylinder pressure.
BrianPetersen wrote "From papers that I've seen, they seem to be developing these based on standard gasoline or diesel engines and the HCCI operating mode is only used at light load - not the condition that gives highest peak cylinder pressure.
The combustion process is very sensitive so the control system must walk a tightrope between misfire and destructive detonation. I have measured between psia in the chambers. As others have mentioned, this is the max design pressures for most commercial CI engines out there, based on thermal and structural limits.
I'm curious as to why there was so much shaking. I had read that it was completely balanced, dynamically. To make it capable of withstanding the high peak cycle pressures bar it was intended to operate at, each piston had two con rods. And the single cylinder test rig had a total of four gear-synchronized, counter rotating cranks. In theory, opposed piston engines have excellent dynamic balance, but in order to improve scavenge efficiency, we usually ran the intake and exhaust pistons up to 10 degrees out of phase.
To make matters worse, the combined reciprocating mass 30 lbs? The test rig was a cu. But even with all of that flywheel mass it still shook the entire building when it ran. The thing that always scared me the most was starting it up. The test rig had no starter, so we would motor it up to speed using the DC dyno, set the externally supplied intake air pressure and temperature to spec, and then begin to turn up the rail pressure control on the 25 ksi fuel injection system.
All of a sudden the thing would light off with a deafening roar and everybody in the control room would jump, even though they had been through the start-up drill dozens of times before. Now that I look back on that program, I'm amazed we never had a serious accident in the test cell. The high pressure common rail fuel system was state of the art for , but it was still a development unit. Being a test rig, we were constantly tearing the engine down for inspection and when we would reinstall the common rail fuel system, it would usually take 4 or 5 attempts to get all of the 25ksi fuel fittings to seal properly.
The fuel pump was engine driven, so we would have to motor up the engine to pressure check the fuel system. I don't know if you've ever seen a leak from a 25ksi fuel system, but one second it's fine and the next instant there's a huge cloud of super-atomized fuel surrounding the engine inside the enclosed test cell. Perfect conditions for a huge explosion. Luckily we never had an explosion.
Maybe God takes pity on fools. Sorry to ramble on, but it was a great program to be involved in and I worked with a lot of sharp guys from Detroit Diesel and Sandia Labs.
I believe they are trying to clean up the emissions and get some higher performance i. Research is both scary and thrilling sometimes, but that is what makes it so fun. Although sometimes it would be calming if we could look into the future a bit to see what things that may leak, break, or blow up.
Especially when working with new engine designs, like the TRC engine. We have a unique opposed, free-piston engine that we are developing right now for the Navy. We have operated this engine in both 2 and 4 stroke modes, which is very unique for a free piston engine. We are using propane in the engine right now to eliminate the need for heating the intake it's throttle body injection , but propane injection has it's own set of difficulties.
We have a port injection for the next prototype so we can incorporate a liquid, heavy fuel delivery system. We have designed the engine for bar and have run pressures about bar so far.
As you open the throttle, intake cylinder pressure goes up and more air and fuel are ingested and more power is made. Also, the higher the cylinder pressure during the intake stroke, the less work the engine has to do to "suck in" the intake air and fuel. This will be discussed later. After the intake stroke, the intake valve closes to trap in the air and fuel. The exhaust valve was already closed during the intake stroke. The actual pressure depends on when the intake valve closes, the pressure in the intake manifold MAP or Manifold Absolute Pressure , Compression Ratio, and other details.
The compression of the air and fuel creates heat and somewhat helps vaporize the fuel. It also takes even more work from the engine to do this compression. Peak cylinder pressures near TDC where spark occurs will be in the range of psi for engine's at light loads, to psi for production engines at full power to psi or greater for race engines.
This is where the engine's power comes from, as it forces the piston down.
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