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Technical Paper

A reduced order turbocharging process model for manifold pressure control with EGR

2019-12-19
2019-01-2212
A mean value turbocharged engine model is useful in terms of accuracy and convenience for fuel economy strategies or engine controller development. Turbocharging process is a feedback system with a positive gain, i.e. increasing exhaust work leads to increasing a cycle work. The gain of the feedback system is determined mainly by exhaust work ratio in a cycle and inertia of the turbine. The work ratio was investigated based on engine test with EGR. A turbocharging process model was obtained using the work ratio in a cycle and theoretical equations. The model is applied to investigate manifold absolute pressure response with EGR.
Technical Paper

An Analysis on Cycle-by-cycle Variation and Trace-knock using a Turbulent Combustion Model Considering a Flame Propagation Mechanism

2019-12-19
2019-01-2207
Gasoline engines have the trace-knock phenomena induced by the fast combustion which happens a few times during 100 cycles. And that constrains the thermal efficiency improvement due to limiting the ignition timing advance. So the authors have been dedicating a trace-knock simulation so that we could obtain any pieces of information associated with trace-knock characteristics. This simulation consists of a turbulent combustion model, a cycle-by-cycle variation model and a chemical calculation subprogram. In the combustion model, a combustion zone is considered in order to obtain proper turbulent combustion speed through wide range of engine speed. From a cycle-by-cycle variation analysis of an actual gasoline engine, some trace-knock features were detected, and they were involved in the cycle-by-cycle variation model. And a reduced elementary reaction model of gasoline PRF (primary reference fuel) was customized to the knocking prediction, and it was used in the chemical calculation.
Technical Paper

Multi Attribute Balancing of NVH, Vehicle Energy Management and Drivability at Early Design Stage Using 1D System Simulation Model

2019-01-09
2019-26-0178
Improving fuel efficiency often affects NVH performance. Modifying a vehicle’s design in the latter stages of development to improve NVH performance is often costly. Therefore, to optimize the cost performance, a Multi-Attribute Balancing (MAB) approach should be employed in the early design phases. This paper proposes a solution based on a unified 1D system simulation model across different vehicle performance areas. In the scope of this paper the following attributes are studied: Fuel economy, Booming, Idle, Engine start and Drivability. The challenges to be solved by 1D simulation are the vehicle performance predictions, taking into account the computation time and accuracy. Early phase studies require a large number of scenarios to evaluate multiple possible parameter combinations employing a multi-attribute approach with a systematic tool to ease setup and evaluation according to the determined performance metrics.
Technical Paper

Development of Momentum Source Model of Vehicle Turbocharger Turbine

2016-04-05
2016-01-0210
Recently, the evaluation of the thermal environment of an engine compartment has become more difficult because of the increased employment and installation of turbochargers. This paper proposes a new prediction model of the momentum source for the turbine of a turbocharger, which is applicable to three-dimensional thermal fluid analyses of vehicle exhaust systems during the actual vehicle development phase. Taking the computational cost into account, the fluid force given by the turbine blades is imitated by adding an external source term to the Navier-Stokes equations corresponding to the optional domain without the computational grids of the actual blades. The mass flow rate through the turbine, blade angle, and number of blade revolutions are used as input data, and then the source is calculated to satisfy the law of the conservation of angular momentum.
Technical Paper

A Reduced Order Turbo-Charging Model for Real Time Engine Torque Profile Control

2015-11-17
2015-32-0766
Torque profile control is one of required technologies for propulsion engines. A smaller parametric model is more preferable for control algorithm design and evaluation. Mean value engine torque can be obtained from throttle opening change using a transfer function. A transfer function for a turbocharged engine was investigated with thermo-dynamic equations for a turbine and a compressor and test data. A small turbocharged engine was tested to model the air transfer process. Turbine speed was measured with temperatures, pressures and air mass flow. Turbine speed response is like a first order system to air mass flow into a combustion chamber. The pressure ratio at the compressor is approximated by a curve proportional to the turbine speed square. Based on those findings, a reduced order model for describing dynamic air transfer process with a turbocharger was constructed. The proposed model is compact and suitable for engine torque control design and controller implementation.
Technical Paper

A Reduced Order Model for a Passenger Car Turbo Charging System and Application to Engine Output Torque Profile Control

2015-09-01
2015-01-1981
Downsizing engines with a turbocharging system have been widely applied to passenger cars to improve fuel economy. Engine torque response to accelerator operation is one of important features in addition to steady state performance of the system. Torque profile management for turbocharged internal combustion engines is one of required technologies. A turbocharging system for a car is a system with a positive feedback loop in which compressed air drives the compressor after the combustion process. A reduced order model was derived for the charging system. Pressure ratio of a compressor is proportional to square of turbine speed and the turbine speed is a first order delay system to throttle opening in the model. Model structure was designed from mathematical equations that describe turbine and compressor works. Model parameters were identified from measured data. An output torque profile control strategy based on the derived model is investigated.
Technical Paper

A Study on Practical Use of Diesel Combustion Calculation and Development of Automatic Optimizing Calculation System

2015-09-01
2015-01-1845
A KIVA code which is customized for passenger car's diesel engines is linked with an engine performance simulator and demonstrated with our optimizing calculation system. Aiming to fulfill our target calculation speed, the combustion model of the KIVA code is changed from a chemical reaction calculation method to a chemical equilibrium calculation method which is introduced a unique technique handling chemical species maps. Those maps contain equilibrium mole fraction data of chemical species according to equivalence ratio and temperature. Linking the KIVA code to the engine simulator helps to evaluate engine performance by indicated mean effective pressure (IMEP). The optimizing calculation system enables to obtain response surfaces. Observing the response surfaces, clear views of engine performance characteristics can be seen. The overview of this calculation system and some examples of the calculation are shown in this paper.
Journal Article

A Study on Knocking Prediction Improvement Using Chemical Reaction Calculation

2015-09-01
2015-01-1905
Compression ratio of newly developed gasoline engines has been increased in order to improve fuel efficiency. But in-cylinder pressure around top dead center (TDC) before spark ignition timing is higher than expectation, because the low temperature oxidization (LTO) generates some heat. The overview of introduced calculation method taking account of the LTO heat of unburned gas, how in-cylinder pressure is revised and some knowledge of knocking prediction using chemical kinetics are shown in this paper.
Technical Paper

Least-Enthalpy Based Control of Cabin Air Recirculation

2015-04-14
2015-01-0372
The vehicle air-conditioning system has significant impact on fuel economy and range of electric vehicles. Improving the fuel economy of vehicles therefore demand for energy efficient climate control systems. Also the emissions regulations motivate the reduced use of fuel for vehicle's cabin climate control. Solar heat gain of the passenger compartment by greenhouse effect is generally treated as the peak thermal load of the climate control system. Although the use of advanced glazing is considered first to reduce solar heat gain other means such as ventilation of parked car and recirculation of cabin air also have impetus for reducing the climate control loads.
Technical Paper

ESC Hydraulic Circuit Modeling and Model Reduction in the Aim of Reaching Real Time Capability

2013-05-15
2013-36-0013
An ESC hydraulic modulator contains on/off valves and proportional valves. A complex model of one proportional valve is detailed and used as a basis for model reduction the activity index technique. One interesting aspect is that the technology of the proportional valves remains (i.e. ball valves under conical seat). As such, the parameters are physical parameters forming the ones to master (manufacturing tolerances) by the supplier to also master the dynamic behavior of the system. Once this has been done, a complete model of half an ESC braking circuit is built including the pump, the reservoir, the pipes and hoses as well as the calipers. The activity index technique is thus reused on the circuit to further reduce it to finally obtain a modeling level acceptable for real time purpose.
Technical Paper

Powertrain Mounting System Layout for Decoupling Rigid-Body Modes in the Vehicle Concept Design Stage

2013-04-08
2013-01-1706
This paper presents a method and corresponding software implementation for powertrain (PWT) mounting system layout design for decoupling rigid-body modes in the torque roll axis system. The novelty in the proposed method is that it requires a minimal set of inputs for determining mount topology, orientation and stiffness properties for decoupling powertrain modes, and as such it can be used at early design stages, unlike the conventional approaches based on analysis and optimization techniques. Consequently, PWT mounts can be positioned and oriented close to their optimal configuration, allowing to develop more realistic full vehicle models for conceptual (or early stage) designs and to run a more accurate dynamic analysis concerning secondary ride and vibrations. The proposed methodology is illustrated on a powertrain mounting system design example case.
Journal Article

Design and Development of a Switching Roller Finger Follower for Discrete Variable Valve Lift in Gasoline Engine Applications

2012-09-10
2012-01-1639
Global environmental and economic concerns regarding increasing fuel consumption and greenhouse gas emission are driving changes to legislative regulations and consumer demand. As regulations become more stringent, advanced engine technologies must be developed and implemented to realize desired benefits. Discrete variable valve lift technology is a targeted means to achieve improved fuel economy in gasoline engines. By limiting intake air flow with an engine valve, as opposed to standard throttling, road-load pumping losses are reduced resulting in improved fuel economy. This paper focuses on the design and development of a switching roller finger follower system which enables two mode discrete variable valve lift on end pivot roller finger follower valvetrains. The system configuration presented includes a four-cylinder passenger car engine with an electro-hydraulic oil control valve, dual feed hydraulic lash adjuster, and switching roller finger follower.
Technical Paper

Time-Domain Source Contribution Analysis Method for In-Room Pass-By Noise

2011-05-17
2011-01-1609
This paper presents a new time-domain source contribution analysis method for in-room pass-by noise. The core of the method is a frequency-domain ASQ model (Airborne Source Quantification) representing each noise generating component (engine, exhaust, left and right tyres, etc.) by a number of acoustic sources. The ASQ model requires the measurement of local FRF's and acoustic noise transfer functions to identify the operational loads from nearby pressure indicator responses and propagate the loads to the various target microphones on the sides of the vehicle. Once a good ASQ model is obtained, FIR filters are constructed, allowing a time-domain synthesis of the various source contributions to each target microphone. The synthesized target response signals are finally recombined into a pass-by sound by taking into account the speed profile of the vehicle.
Technical Paper

Human Driving Behavior Analysis and Model Representation with Expertise Acquiring Process for Controller Rapid Prototyping

2011-04-12
2011-01-0051
Driving car means to control a vehicle according to a target path, e.g. road and speed, with some constraints. Human driving models have been proposed and applied for simulations. However, human control in driving has not been analyzed sufficiently comparing with that of machine control system in term of control theory. Input - output property with internal information processing is not easily measured and described. Response of human driving is not as quicker as that of machine controller but human can learn vehicle response to driving operation and predict target changes. Driving behavior of an expert driver and a beginner in an emission test cycle was measured and difference in target speed tracking was looked into with performance indices. The beginner's operation was less stable than that of the expert. Transfer function of the vehicle system was derived based on linearized model to investigate human driving behavior as a tracking controller in the system.
Technical Paper

A Layer Structured Model Based Diagnosis: Application to a Gear Box System

2011-04-12
2011-01-0753
OBD (On Board Diagnosis) has been applied to detect malfunctions in powertrains. OBD requirements have been extended to detect various failures for ensuring the vehicle emission control system being normal. That causes further costs for additional sensors and software works. Two layers diagnosis system is proposed for a passenger car gearbox system to detect changes from normal behavior. Conventional physical constraints based diagnosis is placed on the base layer. Model based diagnosis and specific symptom finding diagnosis are built on the second layer. Conventional physical constraints based diagnosis is direct and effective way to detect the failure of system if the detected signals exceed their normal ranges. However under the case of system failure with related signals still remain in normal ranges, the conventional detection measures can not work normally. Under this case, Model based diagnosis is proposed to enhance the functionality of diagnosis system.
Technical Paper

Simulating Acoustic Engine Performance Over a Broad Frequency Range

2011-01-19
2011-26-0019
Acoustic performance of vehicle engines is a real challenge for powertrain design engineers. Quiet engines are required to reduce noise pollution and satisfy pass-by noise regulations, but also to improve the driving comfort. Simulation techniques such as the Boundary Element Method (BEM) have already been available for some time and allow predicting the vibro-acoustic response of engines. Although the accuracy of these simulation techniques has been proven, a challenge still remains in the required computation time. Given the large amount of speeds for a full engine run-up and the need to cover a large frequency range, computation times are significant, which limits the possibility to perform many design iterations to optimize the system. In 2001, Acoustic Transfer Vectors (ATV) [1] have been presented to adequately deal with multiple rpm. The ATV provide the acoustic response for unit surface velocities and are therefore independent from the engine's actual surface vibrations.
Technical Paper

Thermal-Mechanical Durability of DOC and DPF After-treatment System for Light Heavy Pickup Truck Application

2009-11-02
2009-01-2707
The US Environmental Protection Agency (EPA)’s heavy duty diesel emission standard was tightened beginning from 2007 with the introduction of ultra-low-sulfur diesel fuel. Most heavy duty diesel applications were required to equip Particulate Matter (PM) after-treatment systems to meet the new tighter, emission standard. Systems utilizing Diesel Oxidation Catalyst (DOC) and Catalyzed-Diesel Particulate Filter (DPF) are a mainstream of modern diesel PM after-treatment systems. To ensure appropriate performance of the system, periodic cleaning of the PM trapped in DPF by its oxidation (a process called “regeneration”) is necessary. As a result, of this regeneration, DOC’s and DPF’s can be exposed to hundreds of thermal cycles during their lifetime. Therefore, to understand the thermo-mechanical performance of the DOC and DPF is an essential issue to evaluate the durability of the system.
Technical Paper

Application of Hydraulic Body Mounts to Reduce the Freeway Hop Shake of Pickup Trucks

2009-05-19
2009-01-2126
When pickup trucks are driven on concrete paved freeways, freeway hop shake is a major complaint. Freeway hop shake occurs when the vehicle passes over the concrete joints of the freeway which impose in-phase harmonic road inputs. These road inputs excite vehicle modes that degrade ride comfort. The worst shake level occurs when the vehicle speed is such that the road input excites the vehicle 1st bending mode and/or the rear wheel hop mode. The hop and bending mode are very close in frequency. This phenomenon is called freeway hop shake. Automotive manufacturers are searching for ways to mitigate freeway hop shake. There are several ways to reduce the shake amplitude. This paper documents a new approach using hydraulic body mounts to reduce the shake. A full vehicle analytical model was used to determine the root cause of the freeway hop shake.
Technical Paper

Optimizing R&H and NVH Performances Early in the Design Process via Multi Body Simulation

2009-05-19
2009-01-2087
This paper presents a CAE based approach to accurately simulate and optimize Ride and Handling metrics. Because of the wide range of vehicle phenomena involved, across the variety of frequency ranges, it is essential that the vehicle model includes proper representation of the dynamic properties of the various subsystems (e.g. tires, steering, PT, etc.) Precise correlation between test and simulation for standalone vehicle components and systems is achieved by replicating in the MBS (Multi-body Simulation) the same tests and boundary conditions. This allows the analyst to correctly define those crucial elements and parameters which have the greatest effect on the R&H attribute to be investigated. Setting up the simulation to correctly represent only one single maneuver simulation at a time would not allow the analyst to consider how the dynamic properties of the chassis design variables should be tuned to achieve to best balance and trade-offs.
Technical Paper

Application of Principle Component Analysis to Low Speed Rear Impact - Design for Six Sigma Project at General Motors

2009-04-20
2009-01-1204
This study involves an application of Principal Component Analysis (PCA) conducted in support of a Design for Six Sigma (DFSS) project. Primary focus of the project is to optimize seat parameters that influence Low Speed Rear Impact (LSRI) whiplash performance. During the DFSS study, the project team identified a need to rank order critical design factors statistically and establish their contribution to LSRI performance. It is also required to develop a transfer function for the LSRI rating in terms of test response parameters that can be used for optimization. This statistical approach resulted in a reliable transfer function that can applied across all seat designs and enabled us to separate vital few parameters from several many.
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