Author(s): Volker Grotheer

Abstract: Can pressure wave interference inside a common-rail accumulator cause measurable cylinder-to-cylinder fueling imbalance, and if so, does targeted damping hardware correct it? This research addressed that question through a combined one-dimensional hydraulic simulation and bench-level injection-rate measurement campaign on a four-cylinder, 1,968 cm³ turbodiesel fuel system operating between 400 and 1,800 bar rail pressure. A baseline configuration without supplementary damping was compared against three damper designs a membrane-type, a Helmholtz-volume type, and a hybrid membrane-Helmholtz arrangement installed at the rail mid-section between cylinders two and three. Injection quantity per shot was recorded over 48 consecutive firing events at each injector station, and the coefficient of variation (CoV) of delivered fuel mass served as the uniformity metric. Without any damper, pressure ripple amplitude reached 37.4 bar peak-to-peak at 1,600 bar nominal rail pressure and 2,400 rpm pump speed, producing a mean injector-to-injector CoV of 5.02%. The membrane-type damper lowered ripple amplitude by 41.3% and CoV to 3.47%. The Helmholtz-volume damper achieved a 53.7% reduction in ripple and brought CoV down to 2.68%. The hybrid device proved most effective, suppressing pulsation amplitude by 68.9% and reducing the delivery CoV to 2.18% across all four injectors. A secondary finding was that cylinder-four the injector farthest from the pump consistently showed the largest undamped variation (CoV 5.38%), yet also exhibited the greatest improvement after hybrid damper installation, falling to 2.28%. One-dimensional wave-propagation analysis confirmed that the hybrid damper disrupted the dominant second-harmonic standing wave responsible for selective enrichment of the end-of-rail injector. These results point to a practical and retrofit-compatible route for tightening fuel delivery spread in existing common-rail architectures without electronic injector-trim recalibration.

DOI: https://www.doi.org/10.22271/27078205.2026.v7.i2a.78

Pages: 01-05 | Views: 130 | Downloads: 61

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