Solution for heavy slow vehicles

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Heavy‑duty fleets need high torque, long life, and low operating cost under tightening emissions and fuel rules. The Relative‑Motion Engine (RME) targets more usable torque at lower RPM, enabling taller gearing, smaller or fewer cylinders, and reduced friction/thermal load—without departing from standard engine physics.

• Background. The ratio of connecting‑rod length to crank radius (L/r) shapes piston motion: dwell near TDC, side‑load on the cylinder wall, and peak acceleration. Lighter, high‑speed passenger engines often use lower L/r for compactness; heavy‑duty slow‑speed engines often favor higher L/r for dwell/torque shaping and durability.
• Implication for RME. Because RME increases cycle work at lower RPM via internal charging, designers can revisit L/r:
  
  • In heavy vehicles, shorter rods (lower L/r) may be acceptable without sacrificing low‑speed torque, improving packaging and mass.
  • In light vehicles, the gain is better used for taller gearing and reduced engine speed for the same road load.

Final L/r selection remains an optimization across side‑load, NVH, packaging, and fatigue; RME expands the feasible design space by delivering torque at lower mean piston speed.

With the RME’s two‑compartment cycle, compression/charging occurs during the return of the power event in the upper pocket while the lower chamber delivers work. Practically, operating points that require ~4,000 rpm in a conventional engine can be targeted at ~2,000 rpm (illustrative) with appropriate gearing—because each cycle contributes useful work.

• Benefit: lower mean piston speed → reduced friction (FMEP), lower inertial loads, and improved durability for bearings, rings, and pins.

• Internal charging each cycle. The floating piston modulates chamber volume to create a pressure‑wave/gas‑spring effect, improving air utilization and mixture prep during the power event—not only before ignition.
• Result: higher indicated torque at lower RPM. With proper gearing, vehicles meet gradeability targets without spinning the engine to traditional speed peaks.

• RME’s pressure‑field can be paired with conventional turbo/supercharging. Because charging assistance acts during the power event, the system aims to extract more benefit per unit of compressor work than strategies that only set pre‑combustion conditions.
• Design intent: raise the useful fraction of compressor work recovered within the cycle. (Component‑level targets >70% are under study; verification will come from dyno measurements and turbomachinery maps.)

• Conventional challenge: heavy vehicles often rely on more cylinders and larger displacement to meet torque at acceptable piston speeds.
• RME option: either downsize displacement while holding torque, or retain size and reduce reliance on large intercoolers and extreme boost—depending on duty cycle.
• Operations: a power‑contributing event every cycle enables lower conventional piston speeds for the same wheel power → less friction, less heat, and potentially smaller cooling packages.

• Combustion noise. By shaping heat‑release timing and moderating the initial pressure rise, RME targets lower pressure‑rise rate (PRR) and combustion noise at the block—beneficial for driver comfort and track/site limits.
• Pollutants. Improved mixture/temperature control at source aims to lower NOx/CO/PM or reduce aftertreatment load; full compliance still uses standard aftertreatment.
• Validation metrics: PRR ≤ design limits (e.g., ≤15 bar/°CA), PCP within hardware limits, tailpipe NOx/PM vs baseline, and ISO noise measurements.

• Gearing: taller final drive and shift strategy to exploit low‑RPM torque.
• Cooling: re‑size radiators/oil coolers based on lower friction and heat rejection (confirm on dyno).
• Driveline: lower RPM reduces harmonic content; review mounts and torsional dampers.
• Maintenance: reduced ring/pin/bearing stress from lower mean piston speed; inspect intervals can be extended subject to fleet data.

• Torque/power maps vs RPM; BSFC at representative duty cycles.
• Airflow & trapped mass vs boost and speed; volumetric efficiency.
• FMEP (motored) and BMEP/BSFC (fired) comparisons.
• Thermal/NVH: coolant/oil heat load; block‑borne noise; vibration spectra.
• Emissions: NOx/CO/PM/PN on standardized drive cycles.

RME enables truck‑class torque at lower RPM, opening options to shorten rods or tall‑gear the driveline, reduce cylinder count or displacement, and shrink cooling/aftertreatment loads—while staying inside conventional engine metrics and validation methods.