Comments by "Mj Yan" (@mjyan3599) on "Repairman22" channel.

  1. You don't have to run the engine to that high speed, except for racing. Our car tires runs at about 500 rpm or below in normal driving, while the ICE operates best at about 2000 rpm. So the engineer use the transmission to match these rpm's together. D-cycle will operate closer to these tire rpms, saving more energy (fuel!).
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  2. The crankshaft operates at 1/2 rpm as 4-cycle. Most 4-cycle in cars need to use transmission to reduce the rpm to the tire rpm from, say, 3,000 rpm to the tire 400rpm through the transmission. Also most 4-cycle cars have only 1/2 of the engine working driving the can. The D-cycle would have the whole engine driving needing only 2-, 3-, or 4-cylinder engines, not those cumbersome v6 or v8 engines.
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  3. It should be noted that the D-cycle engines should 1. at 1/2 rpm of the 4-cycle, 2. there could be only one shaft instead of 2 since these parts are all in the same cycle, 3. most of the engines ike in our cars operate at half peak rpm and half peak loads (not like the racing cars). So D-cycle engine should operate in the "right" region, and plus the Atkinson cycle.
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  4. High Efficiency Low Emission Hybrid ICE: By simply splitting the ring-section from its skirt - to be operated by a (valvetrain-like) piston-train to pump the gases during the intake and exhaust strokes, and combined with the skirt to complete the compression and power strokes - can achieve the hybrid. Which completes the 4 strokes, different in both displacements and periods, in every engine revolution - called D-cycle (Differential-stroke cycle) – a hybrid of the 2-/4-cycles. The D-cycle’s controllable exhaust strokes can be shortened to retain high amount of burnt gases to control the ignition initiation and combustion rates for the HCCI/LTC (homogeneously charged compression ignition with low temperature combustion). When combined with the (gasoline type) stoichiometric air/fuel ratio intake under high-compression ignition, it is the diesel-gasoline hybrid with the benefits of both – called SCCI/LTC-BGR (Burnt Gas Retention). The resultant hybrid can have Atkinson-cycle strokes, whole engine working at lower rpm, fewer cylinders with lighter engine support and vehicle styling, weight and efficiency gains, and etc. Diesel engines can avoid soot and NOx formation saving expensive after treatments with lower noises. Gasoline engines can enjoy diesel type (within structural limitations) efficiency (test shown >20%) and torque gains ( >2.5x).
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  5. ( Notes for D-cycle – following are not obvious, call to discuss: 1. Most piston skirts need not be windowed. 2. Ring sections can be made of stronger thin steel just to hold rings and oil to cool. 3. The same rings stop the oil leaking. 4. The piston-train can run directly from the crankshaft. 5. Crown doesn’t run at higher speed and having Atkinson cycle. The full air intake can be provided via an air 2x pump. 6. Valves don’t run at higher speed, except for fewer cylinder engines. 7. Piston-train spring is compressed during intake. )
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  6. The crown section is operated via a (valvetrain-like) pistontrain. Both -trains can (should!) be operated via the crankshaft eliminating the gear systems. The lighter -trains are operating at higher rpm than the crankshaft.
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  7. It should be noted that this engine needs not to run at high rpms. The tire rotation is about in about 500 rpm or less, while the engine is about 3000 rpm range. These rotation speeds differences are slowed down via the transmission. The D-cycle engine has doubled to tripled torque which need less geared rpm reduction than the popular 4-cycle - that is simpler and lighter vehicle.
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  8. These two cams shafts are rotating at the SAM rpm. There is NO NEED for two cams. The piston-train can operate on the camshaft to eliminate complications.
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  9. Hi, Repairman22, Thanks for your discussion on the split piston ICE. The main idea for it is the huge differences between the gas pumping exhaust and intake strokes and the heavy compression and power strokes for the ICEs. If we split these two functions the engine can run at 1/2 of the rpm for the same work otherwise it will produce 2x (actually 2.5 to 3 times torque). So the crawn section can be redesigned to run at somewhat higher speed with lighter system, since it just pump gases around. Basically, this design make an different hybrid of different kind. Other issues such as: 1. windows in the skirt is not away needed or just a litter cut is enough. 2. the cooling is much easier when stronger and thinner crown is used. 3.there is no oil leak issue if the piston rings are OK, 5. the "extra moving parts basically is the extra cylinder, i.e. i4 becomes v8 (or 2.5 to 3 time output), 6. The engines would run at half rpm, not the 1000rpm, 11. the push-down spring has the help by the the cylinder press at high rpm when the engine is loaded. The crown (piston-train) has about just a little high speed or the same depending upon what differential strokes are designed. The crown section is only to pump the gases around, which much, much lighter than the pushing the whole vehicle around.
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  10. The piston crown part is fixed to the piston stem which in turn is fixed to the pistontrain lever that is constrained to move the stem up-and-down along the cylinder axis. There should be no twisting force on the stem.
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  11. The heavy crankshaft should drive at about 1/2 of the 4-cycle engine. The crown section can be design to be like a thin cup shaped to hold the rings and the piston stem to be operated via the lighter piston-train, which can have higher speed than the heavy crankshaft. The vibration is not much worse, and can be rebalanced. The piston pin is with the skirt, while the rings are with the crown part to seal and rubricate the cylinder. The piston stem can penetrate the pin at the cylinder center line, which does not affect the pin strength. The pin is sized for lubrication, which is much greater than needed for strength.
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  12. Most engines don't rotate more than 6,000 rpm, at about 2,000 ~3500 rpm range instead.
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  13. Yes, the ring section contribute the majority of the piston friction. However, the 4 strokes of the D-cycle can be design for butter engine operations in different strokes, such as longer power stroke for more complete combustions, the right intake for the required amount of intake air for fuel combustion. The right crown speed to exhaust the gases not necessarily the same as the other stroke, etc.
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