The suspension forces due to two different concepts in roll-conected hydro-pneumatic suspension systems, involving hydraulic and pneumatic interconnections, are analytically formulated considering fluid compressibilty, floating piston dynamics, and symmetric and asymmetric damping valves. the formulations are based upon a compact strut design, which integrates damping valves and provides enhanced working area. The roll plane model of a heavy vehicle is further derived for evaluating the relative vertical and roll properties of five different suspension configurations, including unconnected, unconnected with an anti-roll bar, hydraulically interconnected, pneumatically interconnected, and hydraulically interconnected with enhanced roll stiffness. The suspension force formulations clearly show the strong coupling effects of relative motions between the left- and right-struts due to the fluidic interconnections. Comparisons of roll properties of different suspension configurations demonstrate that both hydraulically and pneumatically interconnected suspensions yield enhanced roll stiffness while maintaining soft vertical ride. The hydraulic interconnection further offers improved roll mode damping attributed to the hydraulic coupling effects. The results attained from the parametric studies demonstrated the most significant design flexibility of the fluidic interconnections. The roll stiffness of the connected struts could be easily enhanced by varying the strut geometry, which is unlike a roll bar which could add considerable weight. The relative vertical and roll responses of the vehicle with different suspension configurations are evaluated under excitations arising from tyre interactions with randomly rough roads and discrete bumps, and centrifugal accelerations corresponding to steady and lane change manoeuvres. From the results, it is concluded that fluidic interconnections yield improved roll response, while their vertical ride performance is identical to an unconnected suspension, irrespective of the forward speed and road roughness. The hydraulic interconnection with asymmetric damping, however, yields slightly higher damping in rebound. For directional maoeuvre and crosswind excitations, the roll responses of the vehicle evaluated in terms of sprung mass roll angle and lateral LTR are nearly identical with pneumatic interconnections yield much lower roll angle responses, which tends to decay relatively rapidly and can be attributed to its enhanced roll mode damping and stiffness. The asymmetric damping coupled with hydraulic interconnections also yields improved shock isolation performance under deterministic road bump inputs.
Dynamic analyses of roll plane interconnected hydro-pneumatic suspension systems
Dynamische Analyse der über die Rollebene verbundenen hydropneumatischen Federungssysteme
International Journal of Vehicle Design ; 47 , 1-4 ; 51-80
2008
30 Seiten, 13 Bilder, 2 Tabellen, 22 Quellen
Article (Journal)
English
Anwendung im Fahrzeugbau , Nutzfahrzeug , Fahrzeugfederung , Fahrzeugfahrwerk , Rollbewegung , Stabilität gegen Rollen , Fahrzeugsicherheit , dynamisches Verhalten , Fahrverhalten , Transversalkraft , Fahrstraße , mathematisches Modell , technische Entwicklung , Kompressibilität-Druck-Verhalten , Autoreifen , Dämpfung durch Zähflüssigkeit , hydropneumatische Steuerung , Luftfeder
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