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Technical Paper

Experimental Study of Automotive Heat Shield Geometry with Natural Convection and Radiation Boundary Conditions

2001-05-14
2001-01-1746
Shielding a vehicle underbody is becoming a daunting task with increased exhaust temperatures due to emissions regulations and ever-increasing packaging constraints, which place components ever closer to exhaust systems. This experimental study was initiated to evaluate the two dimensional thermal effects of heat shield flange height and shield width in vehicle underbody idle conditions. The ultimate goal of this study is to develop a function to optimize the shape of heat shielding to achieve a specified floorpan temperature during vehicle idle conditions.
Technical Paper

Air Charge Estimation in Camless Engines

2001-03-05
2001-01-0581
An electromechanically driven valve train offers unprecedented flexibility to optimize engine operation for each speed load point individually. One of the main benefits is the increased fuel economy resulting from unthrottled operation. The absence of a restriction at the entrance of the intake manifold leads to wave propagation in the intake system and makes a direct measurement of air flow with a hot wire air meter unreliable. To deliver the right amount of fuel for a desired air-fuel ratio, we therefore need an open loop estimate of the air flow based on measureable or commanded signals or quantities. This paper investigates various expressions for air charge in camless engines based on quasi-static assumptions for heat transfer and pressure.
Technical Paper

A New Multi-point Active Drawbead Forming Die: Model Development for Process Optimization

1998-02-01
980076
A new press/die system for restraining force control has been developed in order to facilitate an increased level of process control in sheet metal forming. The press features a built-in system for controlling drawbead penetration in real time. The die has local force transducers built into the draw radius of the lower tooling. These sensors are designed to give process information useful for the drawbead control. This paper focuses on developing models of the drawbead actuators and the die shoulder sensors. The actuator model is useful for developing optimal control methods. The sensor characterization is necessary in order to develop a relationship between the raw sensor outputs and a definitive process characteristic such as drawbead restraining force (DBRF). Closed loop control of local specific punch force is demonstrated using the die shoulder sensor and a PID controller developed off-line with the actuator model.
Technical Paper

Global Acoustic Sensitivity Analysis Applied to the Reduction of Shell Noise Radiation of a Simulated Engine Air Induction System Component

1998-02-23
980280
Global acoustic sensitivity analysis [1] is a technique used to identify structural modifications to a component that can reduce the total radiated power of a vibrating structure or the sound pressure levels at specified field points. This report describes the use of global sensitivity analysis within SYSNOISE to determine what structural changes are required to reduce radiated noise from flexible structures in an open duct system. The technique can help optimize design parameters that define the behavior of a flexible structure such as shell thickness and Young's Modulus. The sensitivity analysis approach consists of separately evaluating structural and acoustic sensitivities. A structural finite element model (FEM) of an open duct system is used to compute the sensitivity of the structural response to changes in thickness. A boundary element model (BEM) is then used to relate changes in the calculated acoustic response to changes in the structural design variables.
Technical Paper

Shape Optimization of IC Engine Ports and Chambers

1998-02-23
980127
Intense competition and global regulations in the automotive industry has placed unprecedented demands on the performance, efficiency, and emissions of today's IC engines. The success or failure of a new engine design to meet these often-conflicting requirements is primarily dictated by its capability to provide minimal restriction for the inducted and exhausted flow and by its capability to generate strong large-scale in-cylinder motion. The first criterion is directly linked to power performance of the engine, while the latter has been shown to control the burn rate in IC engines. Enhanced burn rates are favorable to engine efficiency and partial load performance. CFD based Numerical Simulations have recently made it possible to study the development of such engine flows in great details. However, they offer little guidance for modifying the ports and chamber geometry controlling the flow to meet the desired performance.
Technical Paper

Cranktrain Component Conceptual Design and Weight Optimization

1998-02-23
980566
Powertrain Engineering Tool (PET) [1, 2, 3], developed at Ford Powertrain and Vehicle Research Laboratory, is a powertrain computer model that allows rapid development of preliminary powertrain component geometry, and evaluation of engine performance and friction. Based on specified design objectives such as engine torque, power and geometric constraints, PET calculates the powertrain component geometry by employing its integrated design rules and a non-linear SQP-based (Sequential Quadratic Programming) geometry optimizer. PET also generates parametric solid models of powertrain systems based on its integrated dynamic component assembly schemes and solid modeling database. The cranktrain system consists of high-speed moving and rotating components. Complex dynamic analysis is typically required to achieve optimum cranktrain component design. This paper discusses development of a systematic approach in the calculation of optimal cranktrain component geometry.
Technical Paper

Effect of the Variable Switching Frequency and DPWM Switching Schemes on the Losses of Traction Drives

2017-03-28
2017-01-1227
This paper studies different switching schemes for loss reduction in a traction motor drive. The system under examination is composed of a battery, a 2 level Voltage Source Inverter, and an Interior Permanent Magnet motor. Discontinuous PWM (DPWM) control strategy is widely used in this type of motor drive for the reduction of losses. In some publications, the effect of the DPWM modulation scheme is compared to the reduction of the switching frequency which can also cause a reduction in switching losses of the inverter. Extensive studies have examined the effect of variation of the switching frequency on the motor and inverter losses. However, the effect of applying both switching schemes simultaneously has not been explored. This paper will use a system that is operated at a fixed switching frequency as the baseline. Afterwards, three different switching schemes will be studied and compared to the baseline.
Technical Paper

Identification of Permanent Magnet Synchronous Motor Parameters

2017-03-28
2017-01-1237
For high performance motor controls applications such as electric vehicles, accurate motor parameter knowledge is required. Motor parameters like d-axis inductance, q-axis inductance, resistance and permanent magnet flux linkage are difficult to obtain and measure directly. These four parameters can be reduced to three parameters resistance, d-axis and q axis flux linkage. In this paper, a new scheme is proposed to approximate d-axis and q-axis flux linkage using measured torque, dq-axis measured current, and dq-axis voltage commands to the inverter. d-axis and q-axis flux linkages are estimated over a range of d-axis and q-axis currents that fully map the desired motor operation region.
Technical Paper

Geometrical Optimization of an Automotive Halfshaft

2017-03-28
2017-01-1125
Halfshafts are very important components from vehicle powertrain. They are the element responsible to transmit torque and rotation from transmission to wheels. Its most basic design consists of a solid bar with joints at each extreme. Depending of bar length, the natural frequency of first bending mode might have a modal alignment with engine second order, resulting in undesired noise on vehicle interior. Many design alternatives are available to overpass this particular situation, like adding dampers, use tube shafts or use link-shafts, however, all of them are cost affected. This study proposes an investigation to obtain an optimal profile for a solid shaft, pursuing the lowest possible frequency for the first bending mode by changing its diameter at specific regions. The study is divided in four main stages: initially, a modal analysis of a halfshaft is done at vehicle to determinate its natural frequency when assembled on vehicle.
Technical Paper

A Modeling Analysis of Fibrous Media for Gasoline Particulate Filters

2017-03-28
2017-01-0967
With an emerging need for gasoline particulate filters (GPFs) to lower particle emissions from gasoline direct injection (GDI) engines, studies are being conducted to optimize GPF designs in order to balance filtration efficiency, backpressure penalty, filter size, cost and other factors. Metal fiber filters could offer additional designs to the GPF portfolio, which is currently dominated by ceramic wall-flow filters. However, knowledge on their performance as GPFs is still limited. In this study, modeling on backpressure and filtration efficiency of fibrous media was carried out to determine the basic design criteria (filtration area, filter thickness and size) for different target efficiencies and backpressures at given gas flow conditions. Filter media with different fiber sizes (8 - 17 μm) and porosities (80% - 95%) were evaluated using modeling to determine the influence of fiber size and porosity.
Technical Paper

Model Based Engine-Off Natural Vacuum Leak Detection Monitor

2017-03-28
2017-01-1020
Engine-Off Natural Vacuum (EONV) principles based leak detection monitors are designed to determine the presence of a small leak in the fuel tank system. It was introduced to address the ever more stringent emission requirement (currently at 0.02”) for gasoline engine equipped vehicles as proposed by the Environmental Protection Agency (EPA) and California Air Resources Board (CARB) in the United States [2, 3]. Other environmental protection agencies including the ones in EU and China will be adopting similar regulations in the near future. Due to its sensitivity to known noise factors such as the ambient temperature, barometric pressure, drive pattern and parking angle, it has been historically a lower performing monitor that is susceptible to warranty cost or even voluntary recalls. The proposed new model based monitor utilizes production pressure signal and newly instrumented temperature sensors [15].
Technical Paper

Engine Flywheel Failure Avoidance through CAE Optimization

2017-03-28
2017-01-1024
A Flywheel is a rotating mechanical device that evens out the energy fluctuations of an engine and establishes an even crank rotational speed by storing kinetic energy. This paper aims to study the effect of the potential failures on flywheel due to balancing hole position for a proposed grey cast iron material. Any change in its design requires a thorough comprehension of the expected failure modes during operation. For a flywheel, typical failure like crack is very critical for vehicle and occupant safety. Here, CAE test method is adopted for simulating the actual bench tests for design validation of the flywheel. This simulation helps to understand the stresses caused by the structural and thermal loads and recommend design solution which can be readily adopted. The simulation is followed by a rig test where the validation tests are performed for different balancing hole depths. The study revealed that 1. Balancing hole have immense role in crack initiation 2.
Technical Paper

An Extensive Validation of an Open Source Based Solution for Automobile External Aerodynamics

2017-03-28
2017-01-1524
The number of computational fluid dynamics (CFD) simulations performed during the vehicle aerodynamic development process continues to expand at a rapid rate. One key contributor to this trend is the number of analytically based designed experiments performed to support vehicle aerodynamic shape development. A second contributor is the number of aerodynamic optimization studies performed for vehicle exterior components such as mirrors, underbody shields, spoilers, etc. A third contributor is the increasing number of “what if” exploratory studies performed early in the design process when the design is relatively fluid. Licensing costs for commercial CFD solutions can become a significant constraint as the number of simulations expands.
Technical Paper

Time to Torque Optimization by Evolutionary Computation Methods

2017-03-28
2017-01-1629
Time to torque (TTT) is a quantity used to measure the transient torque response of turbocharged engines. It is referred as the time duration from an idle-to-full step torque command to the time when 95% of maximum torque is achieved. In this work, we seek to control multiple engine actuators in a collaborative way such that the TTT is minimized. We pose the TTT minimization problem as an optimization problem by parameterizing each engine actuator’s transient trajectory as Fourier series, followed by minimizing proper cost function with the optimization of those Fourier coefficients. We first investigate the problem in CAE environment by constructing an optimization framework that integrates high-fidelity GT (Gamma Technology) POWER engine model and engine actuators’ Simulink model into ModeFrontier computation platform. We conduct simulation optimization study on two different turbocharged engines under this framework with evolutionary computation algorithms.
Technical Paper

Use of Plastic Trim Fasteners for Automotive Trimming Applications

2017-03-28
2017-01-1304
For many years, the use of in-mold fasteners has been avoided for various reasons including: not fully understanding the load cases in the part, the fear of quality issues occurring, the need for servicing, or the lack of understanding the complexity of all failure modes. The most common solution has been the use of secondary operations to provide attachments, such as, screws, metal clips, heat staking, sonic welding or other methods which are ultimately a waste in the process and an increase in manufacturing costs. The purpose of this paper is to take the reader through the design process followed to design an in-molded attachment clip on plastic parts. The paper explores the design process for in-molded attachment clips beginning with a design concept idea, followed by basic concept testing using a desktop 3D printer, optimizing the design with physical tests and CAE analysis, and finally producing high resolution 3D prototypes for validation and tuning.
Technical Paper

Effective Application of CAE Guidance for Hemmed Closures Throughout the Vehicle Development Process

2017-03-28
2017-01-1310
The perceived quality of automotive closures (flushness and margin) is strongly affected by flanging and hemming of the outer panels and assembly respectively. To improve the quality of closures, the traditional hardware approach needs significant amount of time and costly die re-cuts and trials with prototype panels. Thus, such approach may delay the vehicle program and increase the overall investment cost. The proposed CAE methodology provides upfront design guidance to dies and panels, reduces time and increases cost savings associated with flanging and hemming while improving overall quality of the closures. In this proposed approach, as a first step, analytical formulae and design of experiments (DOE) are followed to estimate magnitude of design parameters of panels and dies as the upfront design guidance.
Technical Paper

Modular Design and Methods to Optimize Seat Complete Assemblies

2017-03-28
2017-01-1309
Modularity in product architecture and its significance in product development have become an important product design topics in the last few decades. Several Product Modularity definitions and methodologies were developed by many researchers; however, most of the definitions and concepts have proliferated to the extent that it is difficult to apply one universal definition for modular product architecture and in product development. Automotive seat modular strategy and key factors for consideration towards modular seat design and assemblies are the main focus of this work. The primary objectives are focused on the most “natural segmentation” of the seat elements (i.e., cushions, backs, trims, plastics, head restraints, etc.) to enable the greatest ease of final assembly and greatest flexibility for scalable feature offerings around common assembly “hard-points.”
Technical Paper

CFD Topology and Shape Optimization for Port Development of Integrated Exhaust Manifolds

2017-03-28
2017-01-1339
Modern cylinder-head designs for gasoline engines are guiding the exhaust gas to the turbocharger system via an integrated exhaust manifold (IEM) which has several advantages like weight and cost reduction. On the other hand, the exhaust ports are running through a package labyrinth and are heavily bent within smallest space. Increased pressure drop, reduced mass flow rate, and deteriorated port flow efficiency could be the consequences leading to higher emissions, increased fuel consumption, and higher knock sensitivity. The optimization of the individual ports by computational fluid dynamics (CFD) is a proper means to minimize or even delete these drawbacks. Meanwhile, there are several powerful optimization methods for three-dimensional flows on the market. In this paper, a combined optimization strategy using CFD topology optimization followed by a shape optimization is presented.
Technical Paper

Design of Automotive Structures Using Multi-Model Optimization

2017-03-28
2017-01-1342
The use of structural optimization in the design of automotive structures is increasingly common. However, it is often challenging to apply these methods simultaneously for different requirements or model configurations. Multi-model optimization (MMO) aims to simplify the iterative design process associated with optimizing multiple parts or configurations with common design variables especially when conflicting requirements exist. In this paper, the use of MMO is demonstrated to evaluate the feasibility of an automotive door concept using an alternative material.
Technical Paper

Secure and Privacy-Preserving Data Collection Mechanisms for Connected Vehicles

2017-03-28
2017-01-1660
Nowadays, the automotive industry is experiencing the advent of unprecedented applications with connected devices, such as identifying safe users for insurance companies or assessing vehicle health. To enable such applications, driving behavior data are collected from vehicles and provided to third parties (e.g., insurance firms, car sharing businesses, healthcare providers). In the new wave of IoT (Internet of Things), driving statistics and users’ data generated from wearable devices can be exploited to better assess driving behaviors and construct driver models. We propose a framework for securely collecting data from multiple sources (e.g., vehicles and brought-in devices) and integrating them in the cloud to enable next-generation services with guaranteed user privacy protection.
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