2008 European Conference Frankfurt am Main October, 20th Variable Valve Actuation System Modelling Integration to the Engine in the environment Paolo Ferreri - Caterina Venezia FPT Research & Mechanical Engineering Basic Technologies Engine Thermo-Fluid Dynamic Systems Department Frankfurt
ling Actuator The technology Modelling of the in the environment Comparison between simulation results experimental data Integration of the (GT-FUEL) to the engine one (GT-Power) Variable Valve Actuation System Modelling Integration to the Engine in the environment 2
ling Actuator Activity objectives development of a of the variable valve actuation system in the environment of the to the engine one in a unique environment Integrated simulations: why? simulation, in engine applications characterized by additional cam lobes like internal EGR lobes engine braking lobes, of the effect on the valve lift of the gas pressures, variable with engine speed load Integrated simulations: to do what? internal EGR analyses engine braking analyses design optimization Variable Valve Actuation System Modelling Integration to the Engine in the environment 3
The Actuator (1/2) ling Actuator An oil volume is interposed between the cam the valve The piston acts as a pump, being its effective displacement controlled by a normally opened solenoid valve The oil layout is divided in high pressure medium pressure zones The valve seating velocity is kept behind safe thresholds by the hydraulic brake orifices An accumulator piston is provided in the medium pressure circuit for the filling recovery after valve lift control (LIVO, EIVC) The system communicates to the engine lubrication system for the fluid losses recovery Variable Valve Actuation System Modelling Integration to the Engine in the environment 4
The Actuator (2/2) ling Actuator Valve lift controls EIVC solenoid valve deactivated before the cam closing angle (Φ2 control) LIVO solenoid valve activated after the cam opening angle (Φ1 control) system benefits - cycle-by-cycle cylinder-bycylinder fully variable valve actuation - volumetric efficiency optimization over the whole engine speeds range - hling of a de-throttled engine - hling of additional cam lobes Variable Valve Actuation System Modelling Integration to the Engine in the environment 5
system Actuator architecture overview High pressure circuit ling Actuator oil circuit Considered application: turbocharged Diesel engine Pump driving system Pump piston unit Flow controller Hydraulic brake unit Solenoid valve NOTE: The picture represents the s of two valves Variable Valve Actuation System Modelling Integration to the Engine in the environment 6
sketch of the Variable Valve Actuation System pump piston unit oil circuit flow controller ling Actuator solenoid valve accumulator unit inlet check valve oil supply hydraulic brake unit HLA valve unit gas pressures interface Variable Valve Actuation System Modelling Integration to the Engine in the environment 7
sketch of the Variable Valve Actuation System Details on the pump piston unit ling motion imposed by the pump driving system pump piston mass + spring lift [mm] iegr lobe crank_angle [deg] MAIN lobe ling oil leakage Actuator pump piston oil chamber Variable Valve Actuation System Modelling Integration to the Engine in the environment 8
sketch of the Variable Valve Actuation System Details on the hydraulic lash adjuster ling contact to the brake piston plunger ling check valve Actuator contact to the valve housing oil leakage HLA s high pressure chamber Variable Valve Actuation System Modelling Integration to the Engine in the environment 9
sketch of the Variable Valve Actuation System Details on the valve unit ling equivalent moving mass force due to duct gas pressure ling Actuator valve spring friction forces force due to incylinder gas pressure Variable Valve Actuation System Modelling Integration to the Engine in the environment 10
sketch of the Variable Valve Actuation System General notes developed with the aim to implement the physics of the system ling geometry of the oil circuit led with an high level of detail evolution of the system considered as adiabatic (heat transfer multiplier of pipes flowsplits set to zero) Actuator global stiffness of the system led as superposition of the hydraulic contribution (oil + free air + oil vapour) the mechanical one (deformation of the pump driving system, pumping of the oil circuit boundaries,...) the flow behaviour of fixed variable opening orifices has been hled developing a dedicated compound template which estimates the discharge coefficient as a function of the instantaneous flow regime (laminar, turbulent) the developed refers to the of one intake valve of a selected engine cylinder Variable Valve Actuation System Modelling Integration to the Engine in the environment 11
Comparison between simulation results experimental data ling Actuator the comparison between simulation results experimental data acquired at the motored test bench is shown in the following slides in two forms: instantaneous patterns of valve lift oil pressure in the high pressure chamber characteristic maps (valve opening closing angles plotted against the solenoid valve electrical control angle Φ1 or Φ2) hot oil temperature different engine speeds valve controls are considered the parameters set of the comes from a preliminary identification Variable Valve Actuation System Modelling Integration to the Engine in the environment 12
Comparison between simulation results experimental data Instantaneous patterns High pressure chamber pressure pattern e_speed: 1000 erpm oil_temp: 090 degc Experiments ling Actuator pressure [bar] supply_press: 4.5 bar (abs.) Φ2 control on iegr MAIN crank_angle [deg] Variable Valve Actuation System Modelling Integration to the Engine in the environment 13
Comparison between simulation results experimental data Instantaneous patterns Valve lift e_speed: 1000 erpm Experiments oil_temp: 090 degc ling Actuator valve lift [mm] supply_press: 4.5 bar (abs.) Φ2 control on iegr MAIN grey dotted curve is representative of the full lift control crank_angle [deg] Variable Valve Actuation System Modelling Integration to the Engine in the environment 14
Comparison between simulation results experimental data Instantaneous patterns High pressure chamber pressure pattern e_speed: 5000 erpm oil_temp: 090 degc Experiments ling Actuator pressure [bar] supply_press: 4.5 bar (abs.) no iegr, full lift on MAIN crank_angle [deg] Variable Valve Actuation System Modelling Integration to the Engine in the environment 15
Comparison between simulation results experimental data Instantaneous patterns Valve lift ling e_speed: 5000 erpm oil_temp: 090 degc supply_press: 4.5 bar (abs.) no iegr, full lift on MAIN Experiments Actuator lift [mm] crank_angle [deg] Variable Valve Actuation System Modelling Integration to the Engine in the environment 16
Comparison between simulation results experimental data Instantaneous patterns High pressure chamber pressure pattern e_speed: 2000 erpm oil_temp: 090 degc Experiments ling Actuator pressure [bar] supply_press: 4.5 bar (abs.) Φ2 on iegr, Φ1 on MAIN crank_angle [deg] Variable Valve Actuation System Modelling Integration to the Engine in the environment 17
Comparison between simulation results experimental data Instantaneous patterns Valve lift e_speed: 2000 erpm Experiments oil_temp: 090 degc ling Actuator valve lift [mm] supply_press: 4.5 bar (abs.) Φ2 on iegr, Φ1 on MAIN grey dotted curve is representative of the full lift control crank_angle [deg] Variable Valve Actuation System Modelling Integration to the Engine in the environment 18
Comparison between simulation results experimental data Instantaneous patterns Valve lift ling e_speed: 1000 erpm oil_temp: 090 degc supply_press: 4.5 bar (abs.) sweep on Φ2 MAIN Experiments zoom on MAIN lift Actuator threshold valve lift for the valve mechanical opening closing angles determination Variable Valve Actuation System Modelling Integration to the Engine in the environment 19
Comparison between simulation results experimental data Actuator characteristic maps - valve closing angle vs SV control Valve closing angle vs electrical Φ2 control ling Actuator valve closing angle [deg] Experiments e_speed: 1000 erpm oil_temp: 090 degc supply_press: 4.5 bar (abs.) sweep on Φ2 MAIN spread [deg] spread on valve closing angle (EXP-CALC) electrical Φ2 angle Variable Valve Actuation System Modelling Integration to the Engine in the environment 20
Engine (GT-Power) (GT-FUEL) coupling system (GT-FUEL) valve lift ling Actuator gas pressures engine (GT-POWER) Variable Valve Actuation System Modelling Integration to the Engine in the environment 21
Gas pressures effect (1/4) engine operating conditions: part load, 2000 erpm, hot oil condition iegr lobe control follows the phasing variation ling cam profile INTAKE (iegr lobes) EXHAUST INTAKE (MAIN lobe) iegr lobe A B C phasing [degrees, crank] 0 - + Φ2_EGR [degrees, crank] x x - x + Actuator SV control B A C crank_angle SV closed SV opened Φ1_EGR Φ2_EGR Φ1_MAIN Φ2_MAIN crank_angle Variable Valve Actuation System Modelling Integration to the Engine in the environment 22
Gas pressures effect (2/4) Effect of the gas pressures for the anticipated lobe (lobe B) valve lift exhaust valve lift intake valve lift from 'hydraulic only' w/o gas pressures intake valve lift from coupled simulations (last cycle) ling Actuator valve_lift [mm] crank_angle [deg] Variable Valve Actuation System Modelling Integration to the Engine in the environment 23
Gas pressures effect (2/4) Effect of the gas pressures for the anticipated lobe (lobe B) valve lift ling Actuator valve_lift [mm] (,, ) exhaust valve lift intake valve lift from 'hydraulic only' w/o gas pressures intake valve lift from coupled simulations (last cycle) in-cylinder gas pressure duct gas pressure Zoom on iegr valve lift gas_pressure [bar] ( _, _ ) crank_angle [deg] Variable Valve Actuation System Modelling Integration to the Engine in the environment 24
Gas pressures effect (3/4) Comparison between the 3 lobe phasings (coupled simulations results) exhaust valve lift lobe_a - intake valve lift from coupled simulations (last cycle) lobe_b - intake valve lift from coupled simulations (last cycle) lobe_c - intake valve lift from coupled simulations (last cycle) ling Actuator valve_lift [mm] crank_angle [deg] Variable Valve Actuation System Modelling Integration to the Engine in the environment 25
Gas pressures effect (3/4) ling Comparison between the 3 lobe phasings (coupled simulations results) exhaust valve lift lobe_a - intake valve lift from coupled simulations (last cycle) lobe_b - intake valve lift from coupled simulations (last cycle) lobe_c - intake valve lift from coupled simulations (last cycle) Zoom on iegr valve lift Actuator valve_lift [mm] B A C crank_angle [deg] Variable Valve Actuation System Modelling Integration to the Engine in the environment 26
Gas pressures effect (4/4) Comparison between the 3 lobe phasings (coupled simulations results) +26 % B +4 % ling A iegr C B A BSFC C Actuator with gas_p w/o gas_p B A C - 47 % NOx Variable Valve Actuation System Modelling Integration to the Engine in the environment 27
Trade-off optimization BSFC-NOx (1/2) engine operating conditions: part load, 2000 erpm, hot oil condition iegr lobe control follows the phasing variation ling Actuator valve_lift [mm] exhaust valve lift lobe_a - intake valve lift from coupled simulations (last cycle) lobe_b - intake valve lift from coupled simulations (last cycle) lobe_c - intake valve lift from coupled simulations (last cycle) best NOx worst BSFC B A C phasing crank_angle [deg] Objective: searching for an iegr lobe phasing relative control in order to improve the BSFC maintaining the NOx of case B Variable Valve Actuation System Modelling Integration to the Engine in the environment 28
Trade-off optimization BSFC-NOx (2/2) exhaust valve lift lobe_a - Fi2iEGR x deg lobe_b - Fi2iEGR (x - 25) deg lobe_a - Fi2iEGR (x + 15) deg A Ø2_ieGR x deg ling valve_lift [mm] B Ø2_ieGR (x 25) deg A Ø2_ieGR (x + 15) deg Actuator crank_angle [deg] iegr lobe Ø2_iEGR [deg] % iegr BSFC NOx B X - 25 ref. ref. ref. A X + 15-2% Variable Valve Actuation System Modelling Integration to the Engine in the environment 29
(1/2) ling Actuator a detailed of the variable valve actuation system has been developed in the environment the elaborated shows a level of accuracy in the description of the real behaviour of the which is generally good over the whole operating range the of the (hydro-mechanical domain) has been integrated to the of the engine (thermo-fluid dynamic domain) with the aim to perform integrated simulations in which the valve lift generated by the hydraulic network takes into account, speed by speed load by load, the effect of the gas pressures the developed tool will allow to perform engine analyses focused on the optimization of additional cam lobes (internal EGR, engine braking) Variable Valve Actuation System Modelling Integration to the Engine in the environment 30
(2/2) the state of the art integrated is characterized by the following situation in term of computational time (one PC equipped with an AMD Dual Core Processor 4400+, 2 GB RAM): ling Actuator engine speed: 2000 erpm oil temperature: 90 degc number of cycles: 70 integrated 6.2 build 10 simulation time: ~ 5 hours (~ 4.3 min/cycle) the complexity reduction /or the distributed computing feature offered by the environment can be considered for the computational time reduction Variable Valve Actuation System Modelling Integration to the Engine in the environment 31
Questions? ling Actuator Thanks to Gamma Technologies in particular to Shawn Harnish for the excellent support...... thank you for your attention Variable Valve Actuation System Modelling Integration to the Engine in the environment 32