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Technical Paper

Modeling of a Wedge Clutch in an Automatic Transmission

2010-04-12
2010-01-0186
A wedge clutch with a wedge ramp transfers the tangential force to an axial force. It has unique features of self-reinforcement and small actuation force, and can be packaged into tight spaces. This wedge clutch can be developed to apply to an automatic transmission (AT) or a hybrid transmission. This paper focuses on the simulation of one wedge clutch in AT during shifting. A mathematical formula is given to describe the self-reinforcement principle of the wedge. The dynamic model of a motor actuated wedge clutch during shifting is built to simulate and develop the control algorithm. The model is implemented in Matlab/Simulink, which includes a DC motor model, a dynamic model of the wedge mechanism and clutch pack, and a driveline model of AT which can simulate a gear shift process. The key characteristics such as variation of normal pressure, response time and energy consumption are evaluated, and the results show a favorable comparison with the traditional hydraulic clutch.
Technical Paper

Effect of Different Magnesium Powertrain Alloys on the High Pressure Die Casting Characteristics of an Automatic Transmission Case

2010-04-12
2010-01-0409
The main objective of this paper is to demonstrate how flow and solidification simulation were used in the development of a new gating system design for three different magnesium alloys; and to determine the relative castability of each alloy based on casting trials. Prototype tooling for an existing 3-slide rear wheel drive automatic transmission case designed for aluminum A380 was provided by General Motors. Flow and solidification simulation were performed using Magmasoft on the existing runner system design using A380 (baseline), AE44, MRI153M and MRI230D. Based on the filling results, new designs were developed at Meridian for the magnesium alloys. Subsequent modeling was performed to verify the new design and the changes were incorporated into the prototype tool. Casting trials were conducted with the three magnesium alloys and the relative castability was evaluated.
Technical Paper

CFD Analysis of Oil/Gas Flow in Piston Ring-Pack

2011-04-12
2011-01-1406
The oil consumption and blow-by are complex phenomena that need to be minimized to meet the ever changing modern emission standards. Oil flows from the sump to the combustion chamber and the blow-by gases flow from the combustion chamber to the crank case. There are several piston rings on the piston, which form a ring-pack. The ring pack has to be efficiently designed to minimize the oil consumption and blow-by. Since it is difficult and extremely costly to conduct experiments on every series of engines to check for the blow-by and oil consumption, a CFD analysis can be performed on the ring pack to study the blow-by and oil-consumption characteristics. In the CFD analysis described here, the region considered is between the compression chamber and the skirt, between the piston (including the rings) and the cylinder liner. The 3D CFD analysis was conducted for the engine running conditions of 5000 rpm and load of 13.5 kPa, for a 2.4L gasoline engine.
Technical Paper

Particulate Characteristics for Varying Engine Operation in a Gasoline Spark Ignited, Direct Injection Engine

2011-04-12
2011-01-1220
The objective of this research is a detailed investigation of particulate sizing and number count from a spark-ignited, direct-injection (SIDI) engine at different operating conditions. The engine is a 549 [cc] single-cylinder, four-valve engine with a flat-top piston, fueled by Tier II EEE. A baseline engine operating condition, with a low number of particulates, was established and repeatability at this condition was ascertained. This baseline condition is specified as 2000 rpm, 320 kPa IMEP, 280 [°bTDC] end of injection (EOI), and 25 [°bTDC] ignition timing. The particle size distributions were recorded for particle sizes between 7 and 289 [nm]. The baseline particle size distribution was relatively flat, around 1E6 [dN/dlogDp], for particle diameters between 7 and 100 [nm], before dropping off to decreasing numbers at larger diameters. Distributions resulting from a matrix of different engine conditions were recorded.
Technical Paper

Damping Mass Effects on Panel Sound Transmission Loss

2011-05-17
2011-01-1633
The primary function of damping treatment on a vibrating panel in a vehicle is to reduce vibration levels or radiated sound power by the dissipation of energy. However, in automotive applications the mass effects of damping materials should not be ignored, especially with regard to airborne noise performance. In this paper, a Finite Element-Statistical Energy Analysis (FE-SEA) hybrid analysis is used to evaluate the mass effects of applied damping materials on Sound Transmission Loss (STL). The analysis takes into consideration effects on both the elastic properties and modal mass of the panel. It is shown that while uniformly distributing the mass of the damping material over the panel generally over-estimate the mass effects on STL, an area weighting approach underestimates the effects. Results are confirmed by laboratory testing. A nomogram is generated to show the total effect of the mass of the damping material on STL.
Technical Paper

Defining In-Vehicle Location and Functional Attributes of a ‘Button-Style Electronic Automatic Transmission Shifter’ Using DFSS Methodology with Customer Clinic Approach

2017-03-28
2017-01-1131
The implementation of electronic shifters (e-shifter) for automatic transmissions in vehicles has created many new opportunities for the customer facing transmission interface and in-vehicle packaging. E-shifters have become popular in recent years as their smaller physical size leads to packaging advantages, they reduce the mass of the automatic transmission shift system, they are easier to install during vehicle assembly, and act as an enabler for autonomous driving. A button-style e-shifter has the ability to create a unique customer interface to the automatic transmission, as it is very different from the conventional column lever or linear console shifter. In addition to this, a button-style e-shifter can free the center console of valuable package space for other customer-facing functions, such as storage bins and Human-Machine Interface controllers.
Technical Paper

Utilizing a Tracked 3-Dimensional Acoustic Probe in the Development of an Automotive Front-of-Dash

2017-06-05
2017-01-1869
During the development of an automotive acoustic package, valuable information can be gained by visualizing the acoustic energy flow through the Front-of-Dash (FOD) when a sound source is placed in the engine compartment. Two of the commonly used methods for generating the visual map of the acoustic field include Sound Intensity measurements and array technologies. An alternative method is to use a tracked 3-dimensional acoustic probe to scan and visualize the FOD in real-time when the sound source is injecting noise into the engine compartment. The scan is used to focus the development of the FOD acoustic package on the weakest areas by identifying acoustic leaks and locations with low Transmission Loss. This paper provides a brief discussion of the capabilities of the tracked 3-D acoustic probe, and presents examples of the implementation of the probe during the development of the FOD acoustic package for two mid-sized sedans.
Technical Paper

Experimental GT-POWER Correlation Techniques and Best Practices Low Frequency Acoustic Modeling of the Exhaust System of a Naturally Aspirated Engine

2017-06-05
2017-01-1793
As regulations become increasingly stringent and customer expectations of vehicle refinement increase, the accurate control and prediction of exhaust system airborne acoustics are a critical factor in creating a vehicle that wins in the marketplace. The goal of this project was to improve the predicative accuracy of the GT-power engine and exhaust model and to update internal best practices for modeling. This paper will explore the details of an exhaust focused correlation project that was performed on a naturally aspirated spark ignition eight-cylinder engine. This paper and SAE paper “Experimental GT-POWER Correlation Techniques and Best Practices Low Frequency Acoustic Modeling of the Intake System of a Turbocharged Engine” share similar abstracts and introductions; however, they were split for readability and to keep the focus on a single a single subsystem.
Technical Paper

Experimental GT-POWER Correlation Techniques and Best Practices Low Frequency Acoustic Modeling of the Intake System of a Turbocharged Engine

2017-06-05
2017-01-1794
As regulations become increasingly stringent and customer expectations of vehicle refinement increase, the accurate control and prediction of induction system airborne acoustics are a critical factor in creating a vehicle that wins in the marketplace. The goal of this project was to improve the predicative accuracy of a 1-D GT-power engine and induction model and to update internal best practices for modeling. The paper will explore the details of an induction focused correlation project that was performed on a spark ignition turbocharged inline four-cylinder engine. This paper and SAE paper “Experimental GT-POWER Correlation Techniques and Best Practices” share similar abstracts and introductions; however, they were split for readability and to keep the focus on a single a single subsystem. This paper compares 1D GT-Power engine air induction system (AIS) sound predictions with chassis dyno experimental measurements during a fixed gear, full-load speed sweep.
Technical Paper

Self-Certification Requirements for Adaptive Driving Beam Headlamps

2017-03-28
2017-01-1365
Vehicle certification requirements generally fall into 2 categories: self-certification and various forms of type approval. Self-certification requirements used in the United States under Federal Motor Vehicle Safety Standards (FMVSS) regulations must be objective and measurable with clear pass / fail criteria. On the other hand, Type Approval requirements used in Europe under United Nations Economic Commission for Europe (UNECE) regulations can be more open ended, relying on the mandated 3rd party certification agency to appropriately interpret and apply the requirements based on the design and configuration of a vehicle. The use of 3rd party certification is especially helpful when applying regulatory requirements for complex vehicle systems that operate dynamically, changing based on inputs from the surrounding environment. One such system is Adaptive Driving Beam (ADB).
Technical Paper

Traditional and Electronic Solutions to Mitigate Electrified Vehicle Driveline Noises

2017-06-05
2017-01-1755
Hybrid powertrain vehicles inherently create discontinuous sounds during operation. The discontinuous noise created from the electrical motors during transition states are undesirable since they can create tones that do not correlate with the dynamics of the vehicle. The audible level of these motor whines and discontinuous tones can be reduced via common noise abatement techniques or reducing the amount of regeneration braking. One electronic solution which does not affect mass or fuel economy is Masking Sound Enhancement (MSE). MSE is an algorithm that uses the infotainment system to mask the naturally occurring discontinuous hybrid drive unit and driveline tones. MSE enables a variety of benefits, such as more aggressive regenerative braking strategies which yield higher levels of fuel economy and results in a more pleasing interior vehicle powertrain sound. This paper will discuss the techniques and signals used to implement MSE in a hybrid powertrain equipped vehicle.
Technical Paper

Comparison of Stochastic Pre-Ignition Behaviors on a Turbocharged Gasoline Engine with Various Fuels and Lubricants

2016-10-17
2016-01-2291
Stochastic pre-ignition (SPI) has been commonly observed in turbocharged spark-ignition direct-injection (SIDI) engines at low-speed and high-load conditions, which causes extremely high cylinder pressures that can damage an engine immediately or degrade the engine life. The compositions and properties of fuels and lubricants have shown a strong impact on SPI frequency. This study experimentally evaluated SPI behaviors on a 2.0-liter 4-cylinder turbocharged SIDI engine with China V market fuel and China fuel blended to US Tier II fuel specifications. China V market fuel showed significantly higher SPI frequency and severity than China blended US Tier II fuel, which was attributed to its lower volatility between 100 °C to 150 °C (or lower T60 to T90 in the distillation curve). Two different formulations of lubricant oils were also tested and their impact on SPI were compared.
Technical Paper

Self-Tuning PID Design for Slip Control of Wedge Clutches

2017-03-28
2017-01-1112
The wedge clutch takes advantages of small actuation force/torque, space-saving and energy-saving. However, big challenge arises from the varying self-reinforced ratio due to the varying friction coefficient inevitably affected by temperature and wear. In order to improve the smoothness and synchronization time of the slipping process of the wedge clutch, this paper proposes a self-tuning PID controller based on Lyapunov principle. A new Lyapunov function is developed for the wedge clutch system. Simulation results show that the self-tuning PID obtains much less error than the conventional PID with fixed gains. Moreover, the self-tuning PID is more adaptable to the variation of the friction coefficient for the error is about 1/5 of the conventional PID.
Technical Paper

A System of Systems Approach to Automotive Challenges

2018-04-03
2018-01-0752
The automotive industry is facing many significant challenges that go far beyond the design and manufacturing of automobile products. Connected, autonomous and electric vehicles, smart cities, urbanization and the car sharing economy all present challenges in a fast-changing environment which the automotive industry must adapt to. Cars no longer are just standalone systems, but have become constituent systems (CS) in larger System of Systems (SoS) context. This is reflected in the emergence of several acronyms such as vehicle-to-everything (V2X), vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), and vehicle-to-grid (V2G) expressions. System of Systems are defined systems of interest whose elements (constituent systems) are managerially and operationally independent systems. This interoperating and/or integrated collection of constituent systems usually produce results unachievable by the individual systems alone, for example the use of car batteries as virtual power plants.
Technical Paper

System Engineering for Automated Software Update of Automotive Electronics

2018-04-03
2018-01-0750
In traditional automotive electronic design, software update has been a component oriented, manual process rather than a systematic designed in capability suitable for automation. In recent days as software content in vehicles grow, the need to update software in vehicles more frequently is becoming a necessity. Moreover, additional attributes for software updates, for example timely delivery of security related update for vehicles, desire to add features using software update, control cost of software updates, etc., requires a system engineered design rather than a component oriented approach. As the automobile domain utilizes various means of mobility (Combustion Engine, Hybrid, Battery, etc.) and various functional domains (Infotainment, Safety, Mobility, Telematics, ADAS (Advance Driving Assist service), Autonomous, etc.), to control the overall cost of future software update for such a diverse environment, it is beneficial to introduce automation in the software update process.
Technical Paper

Initial Comparisons of Friction Stir Spot Welding and Self Piercing Riveting of Ultra-Thin Steel Sheet

2018-04-03
2018-01-1236
Due to the limitations on resistance spot welding of ultra-thin steel sheet (thicknesses below 0.5 mm) in high-volume automotive manufacturing, a comparison of friction stir spot welding and self-piercing riveting was performed to determine which process may be more amenable to enabling assembly of ultra-thin steel sheet. Statistical comparisons between mechanical properties of lap-shear tensile and T-peel were made in sheet thickness below 0.5 mm and for dissimilar thickness combinations. An evaluation of energy to fracture, fracture mechanisms, and joint consistency is presented.
Technical Paper

Spark Assist for CA50 Control and Improved Robustness in a Premixed LTGC Engine – Effects of Equivalence Ratio and Intake Boost

2018-04-03
2018-01-1252
Low-temperature gasoline combustion (LTGC) engines can deliver high efficiencies, with ultra-low emissions of nitrogen oxides (NOx) and particulate matter (PM). However, controlling the combustion timing and maintaining robust operation remains a challenge for LTGC engines. One promising technique to overcoming these challenges is spark assist (SA). In this work, well-controlled, fully premixed experiments are performed in a single-cylinder LTGC research engine at 1200 rpm using a cylinder head modified to accommodate a spark plug. Compression ratios (CR) of 16:1 and 14:1 were used during the experiments. Two different fuels were also tested, with properties representative of premium- and regular-grade market gasolines. SA was found to work well for both CRs and fuels. The equivalence ratio (ϕ) limits and the effect of intake-pressure boost on the ability of SA to compensate for a reduced Tin were studied. For the conditions studied, ϕ=0.42 was found to be most effective for SA.
Technical Paper

Supervisory Model Predictive Control of a Powertrain with a Continuously Variable Transmission

2018-04-03
2018-01-0860
This paper describes the design of a supervisory multivariable constrained Model Predictive Control (MPC) system for driver requested axle torque tracking with real-time fuel economy optimization that is scheduled for production by General Motors starting in 2018. The control system has been conceived and co-developed by General Motors and ODYS. The control approach consists of a set of linear MPC controllers scheduled in real-time based on powertrain operating conditions. For each MPC controller, a linear model is obtained by system identification with vehicle and dynamometer data. The supervisory MPC coordinates in real time desired Continuously Variable Transmission (CVT) ratio and desired engine torque to satisfy the system requirements, based on estimates of axle torque and engine fuel rate, by solving a constrained optimization problem at each sampling step. Each linear MPC controller is equipped with a Kalman filter to reconstruct the system state from available measurements.
Technical Paper

Learning Gasoline Direct Injector Dynamics Using Artificial Neural Networks

2018-04-03
2018-01-0863
In today’s race for improved fuel economy and lower emissions from gasoline engines, precise metering of delivered fuel is essential. Gasoline Direct Injection fuel systems provide the means for improved combustion efficiency through mixture preparation and better atomization. These improvements can be achieved from both increasing fuel pressure and using multiple injection events, which significantly reduce the required energizing time per injection, and in a number of cases, force the injector to operate at less than full stroke. When the injector operates in this condition, the influence of variation in injector dynamics account for a large percentage of the delivered fuel and require compensation to ensure accurate fuel delivery. Injector dynamics such as opening delay and closing time are influenced by operating conditions such as fuel pressure, energizing time, and temperature.
Technical Paper

Model Predictive Control of Turbocharged Gasoline Engines for Mass Production

2018-04-03
2018-01-0875
This paper describes the design of a multivariable, constrained Model Predictive Control (MPC) system for torque tracking in turbocharged gasoline engines scheduled for production by General Motors starting in calendar year 2018. The control system has been conceived and co-developed by General Motors and ODYS. The control approach consists of a set of linear MPC controllers scheduled in real time based on engine operating conditions. For each MPC controller, a linear model is obtained by system identification with data collected from engines. The control system coordinates throttle, wastegate, intake and exhaust cams in real time to track a desired engine torque profile, based on measurements and estimates of engine torque and intake manifold pressure.
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