Daniel Barba

Development and Testing of an Automatic Transmission Shift Schedule Algorithm for Vehicle Simulation

The Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) tool was created by EPA to estimate greenhouse gas (GHG) emissions from light-duty (LD) vehicles [1]. ALPHA is a physics-based, forward-looking, full vehicle computer simulation capable of analyzing various vehicle types combined with different powertrain technologies. The software tool is a MATLAB/Simulink based desktop application. In order to model the behavior of current and future vehicles, an algorithm was developed to dynamically generate transmission shift logic from a set of user-defined parameters, a cost function (e.g., engine fuel consumption) and vehicle performance during simulation. This paper presents ALPHAs shift logic algorithm and compares its predicted shift points to actual shift points from a mid-size light-duty vehicle and to the shift points predicted using a static table-based shift logic as calibrated to the same vehicle during benchmark testing. An explanation of, and a process for tuning, the user defined parameters is presented and example applications of the algorithm in transmission and engine sensitivity studies are described.

Benchmarking and Modeling of a Conventional Mid-Size Car Using ALPHA

The Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) tool was created by EPA to evaluate the Greenhouse Gas (GHG) emissions of Light-Duty (LD) vehicles [1]. ALPHA is a physicsbased, forward-looking, full vehicle computer simulation capable of analyzing various vehicle types combined with different powertrain technologies. The software tool is a MATLAB/Simulink based desktop application. The ALPHA model has been updated from the previous version to include more realistic vehicle behavior and now includes internal auditing of all energy flows in the model. As a result of the model refinements and in preparation for the mid-term evaluation of the 2017-2025 LD GHG rule, we are revalidating the model with newly acquired vehicle data. This paper presents the benchmarking, modeling and continued testing of a 2013 Chevy Malibu 1LS. During the initial benchmarking phase, the engine and transmission were removed from the vehicle and tested and evaluated on separate test stands. Data from the benchmarking was provided to the ALPHA model to perform full vehicle simulations over several drive cycles and vehicle road loads. Subsequently, the vehicle was reassembled and underwent further evaluation and testing to refine the inputs to the model. This paper presents the collected data, the methods for developing the model inputs from the data, the results of running the ALPHA model, and the lessons learned during the modeling and assessment activity.

Vehicle Component Benchmarking Using a Chassis Dynamometer

The benchmarking study described in this paper uses data from chassis dynamometer testing to determine the efficiency and operation of vehicle driveline components. A robust test procedure was created that can be followed with no a priori knowledge of component performance, nor additional instrumentation installed in the vehicle. To develop the procedure, a 2013 Chevrolet Malibu was tested on a chassis dynamometer. Dynamometer data, emissions data, and data from the vehicle controller area network (CAN) bus were used to construct efficiency maps for the engine and transmission. These maps were compared to maps of the same components produced from standalone component benchmarking, resulting in a good match between results from in-vehicle and standalone testing. The benchmarking methodology was extended to a 2013 Mercedes E350 diesel vehicle. Dynamometer, emissions, and CAN data were used to construct efficiency maps and operation strategies for the engine and transmission. These maps were used in EP As Advanced Light-duty Powertrain and Hybrid Analysis Tool (ALPHA) vehicle model, which showed a good agreement between the modeled fuel economy and dynamometer test results.

Investigating the Effect of Advanced Automatic Transmissions on Fuel Consumption Using Vehicle Testing and Modeling

In preparation for the midterm evaluation (MTE) of the 2022-2025 Light-Duty Greenhouse Gas (LD GHG) emissions standards, the Environmental Protection Agency (EPA) is refining and revalidating their Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) tool using newly acquired data from model year 2013-2015 engines and vehicles. ALPHA is a physics-based, forwardlooking, full vehicle computer simulation capable of analyzing various vehicle types with different powertrain technologies, showing realistic vehicle behavior, and auditing of all internal ener gy flows in the model. As part of the validation of ALPHA, the EPA obtained model year 2014 Dodge Chargers equipped with 3.6 liter V6 engines and either a NAG1 five-speed automatic transmission or an 845RE eight-speed automatic transmission. Vehicles were tested on a chassis dynamometer; test results showed eight-speed vehicles averaging 6.5% reduction in unadjusted combined city-highway fuel consumption compared to five-speed vehicles. In addition, an 845RE eight-speed transmission was obtained and tested in a standalone transmission test rig. The measured transmission parameters were used in ALPHA to simulate the behavior and fuel consumption of the eight-speed Dodge Charger. A companion model for the five-speed Charger was also constructed; the resulting simulated fuel consumption for both vehicles closely matched the test results. This paper uses the validated ALPHA model to predict the effectiveness improvement of real-world transmissions over a baseline circa 2008 four-speed transmission, and to predict further improvements possible from future eight-speed transmissions. To that end, transmission models for a four-speed automatic transmission and future eight-speed automatic transmissions were constructed, and ALPHA was used to predict the fuel consumption differences of a Dodge Charger equipped with these transmissions. A fuel consumption reduction of over 12% was predicted when comparing a future eight-speed transmission to a baseline four-speed. Predicted fuel consumption reduction was over 16% when the engines were resized to maintain a constant acceleration performance.

Modeling of a Conventional Mid-Size Car with CVT Using ALPHA and Comparable Powertrain Technologies

The Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) tool was created by EPA to evaluate the Greenhouse Gas (GHG) emissions of Light-Duty (LD) vehicles [1]. ALPHA is a physicsbased, forward-looking, full vehicle computer simulation capable of analyzing various vehicle types combined with different powertrain technologies. The software tool is a MATLAB/Simulink based desktop application. The ALPHA model has been updated from the previous version to include more realistic vehicle behavior and now includes internal auditing of all energy flows in the model [2]. As a result of the model refinements and in preparation for the mid-term evaluation (MTE) of the 2022-2025 LD GHG emissions standards, the model is being revalidated with newly acquired vehicle data. In the effort to model the current and future US Light-Duty fleet there are times when complete and exact engine and powertrain component data are unavailable and must be approximated using components with comparable levels of performance and technology. This paper presents the testing and ALPHA modeling of a CVT-equipped 2013 Nissan Altima 2.5S using comparable powertrain technology inputs. A brief overview of recent improvements in CVT performance and efficiency is provided. ALPHA’s CVT shift strategy, ALPHAshiftCVT, is introduced and its performance is compared with data from the Altima. Fuel economy and carbon emissions results over a wide range of drive cycles were within 5% of measured values and the city/highway weighted combined fuel economy and carbon emissions were within approximately 1% of measured values, providing confidence in the proxy powertrain approach.

Estimating GHG Reduction from Combinations of Current Best-Available and Future Powertrain and Vehicle Technologies for a Midsized Car Using EPA's ALPHA Model

The Environmental Protection Agency’s (EPA’s) Advanced LightDuty Powertrain and Hybrid Analysis (ALPHA) tool was created to estimate greenhouse gas (GHG) emissions from light-duty vehicles[1]. ALPHA is a physics-based, forward-looking, full vehicle computer simulation capable of analyzing various vehicle types with different powertrain technologies, showing realistic vehicle behavior, and auditing of all internal energy flows in the model. The software tool is a MATLAB/Simulink based desktop application. In preparation for the midterm evaluation of the light-duty GHG emission standards for model years 2022-2025, EPA is refining and revalidating ALPHA using newly acquired data from model year 2013-2015 engines and vehicles. From its database of engine and vehicle benchmarking data EPA identified the most efficient, engines, transmissions and vehicle technologies, and then used ALPHA to model a midsized car incorporating combinations of these existing technologies which minimize GHG emissions. In a similar analysis, ALPHA was used to estimate the GHG emissions from future low-GHG technology packages potentially available in model year 2025. This paper presents the ALPHA model inputs, results and the lessons learned during this modeling and assessment activity.

Constructing Engine Maps for Full Vehicle Simulation Modeling

The Environmental Protection Agency (EPA) has collected a variety of engine and vehicle test data to assess the efectiveness of new automotive technologies in meeting greenhouse gas (GHG) and criteria emission standards and to monitor their behavior in real world operation. EPA’s Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) tool was created to estimate GHG emissions from vehicles using various combinations of advanced technologies and has been refned using data from testing conducted at EPA’s National Vehicle and Fuel Emissions Laboratory.

Evaluation of Emerging Technologies on a 1.6 L Turbocharged GDI Engine

Low-pressure loop exhaust gas recirculation (LPEGR) combined with higher compression ratio, is a technology package that has been a focus of research to increase engine thermal efficiency of downsized, turbocharged gasoline direct injection (GDI) engines. Research shows that the addition of LPEGR reduces the propensity to knock that is experienced at higher compression ratios [1]. To investigate the interaction and compatibility between increased compression ratio and LP-EGR, a 1.6 L Turbocharged GDI engine was modified to run with LP-EGR at a higher compression ratio (12:1 versus 10.5:1) via a piston change. This paper presents the results of the baseline testing on an engine run with a prototype controller and initially tuned to mimic an original equipment manufacturer (OEM) baseline control strategy running on premium fuel (92.8 anti-knock index). This paper then presents test results after first adding LP-EGR to the baseline engine, and then also increasing the compression ratio (CR) using 12:1 pistons. As a last step, the 10.5 CR engine with LP-EGR was run on regular fuel (87.7 antiknock index) to verify that this configuration could be calibrated to maintain performance like the baseline engine running on premium fuel. To understand the effect of each technology and operating strategy combination on vehicle fuel economy, the various engine maps were compared in EPA’s Advanced Light-Duty Powertrain and Hybrid Analysis (ALPHA) tool over U.S. regulatory drive cycles. This work was done in close collaboration with U.S. EPA engineers as part of their continuing assessment of advanced light-duty automotive technologies to support setting appropriate national greenhouse gas standards. Introduction By 2025, the automotive industry will be required to have reduced carbon dioxide (CO2) emissions by at least 30% and non-methane organic gases and oxides of nitrogen (NMOG+NOx) by 80% [2, 3]. A commonly used strategy to improve fleet-wide emissions reduction is engine downsizing. A downsized engine has a reduced engine displacement but a higher specific power, usually via forced induction to maintain overall performance. By reducing engine displacement, the engine can operate at a higher, more efficient load to produce the same vehicle-required power, thus giving an overall efficiency improvement. However, operating the engine at higher loads will increase the propensity for engine knock to occur. Knock can be mitigated by retarding ignition timing to permit higher load operation but with reduced efficiency. One other method to increase efficiency is to increase the geometric compression ratio (CR). However, high compression ratios also raise compression temperatures, which can increase knock propensity. Thus, the CR on highly boosted, downsized engines is limited to avoid engine knock. One promising strategy to increase efficiency on downsized engines is the use of cooled exhaust gas recirculation (EGR). Cooled EGR leads to higher thermal efficiencies through a reduction in heat transfer losses as well as improving the working fluid. One further benefit of cooled EGR is a reduction in knock, which enables higher CRs and more optimized combustion phasing [4, 5, 6, 7, 8, 9, 10, 11]. EGR can reduce knock propensity through thermodynamic cooling and chemical effects. The high specific heat capacity of CO2 and H2O reduces the temperature driving autoignition reactions. Regarding chemical effects, there are several aspects. Firstly, the reduction of O2 with dilution does not significantly contribute to reduced knock propensity in single-stage autoignition fuels, such as gasoline [8]. Trace species of unburned HC, CO or NO can advance or retard the onset of knock depending on the fuel type. There is ongoing debate regarding the significance of EGR and knock mitigation depending on the test fuel and pressure, temperature operating region. Research has attribute the effectiveness of EGR to the fuel and pressure, temperature history of the gas [5, 7, 9]. At high pressure conditions, the effectiveness of EGR to mitigate autoignition reduces [7] and therefore the relevance of cooled LP-EGR on boosted engines may be less significant. Cooled EGR also offers specificheat related benefits by displacing the diatomic air molecules with triatomic molecules circulated back from the exhaust. The increase in heat capacity results in reduced combustion temperatures leading to lower NOX, CO and PM emissions [12, 13, 14]. As a diluent, the use of cooled EGR can provide a pumping benefit, although at lower loads, where pumping is a primary concern, internal trapped residuals are favored over external EGR [15]. Overall, the level of improvement from adding EGR to a gasoline engine, independent of other considerations such as downsizing or hybridization or separate pumping loss mitigation technologies (i.e. variable valve lift and duration, late/early intake valve closing, etc.), has been shown to be approximately 6-8% on cycles such as the New European Driving Cycle (NEDC) [14] and potentially more on more highly loaded cycles such as the Federal Test Procedure (FTP-75). Certainly, cooled EGR concepts are becoming more prevalent as evidenced by several production applications for high efficiency spark ignited (SI) engines [16, 17]. Another potential efficiency path is by reducing the effective CR of the engine but maintaining a high expansion ratio. Some recent production engines and research [18, 19, 20] employ a Miller or Atkinsoncycle strategy where the intake valve is closed before or after piston bottom-dead-center (BDC) to reduce the effective CR, which avoids knock but maintains the high expansion ratio to realize efficiency. A challenge of Miller or Atkinson-cycle operation is a reduction in charge motion, required for fuel mixing and fast burn rates, as well as low volumetric efficiency which leads to higher boost requirements. Like Miller-cycle operation, the use of cooled EGR reduces the mass of fresh air available for combustion, thus limiting engine performance. To increase the density of the charge, turbocharging and intercooling are commonly used to increase the pressure and reduce the temperature, respectively. A boost device such as a turbocharger converts exhaust enthalpy into useful work compressing air on the intake side. EGR leads to cooler exhaust temperatures and therefore lower exhaust enthalpy. The combination of high pressure ratio and low exhaust enthalpy generally requires a smaller compressor and turbine wheel to achieve the low engine speed brake mean effective pressure (BMEP) targets. At higher speeds, the device may be undersized, and the compressor would choke under the flow demands. It is difficult to use a single-boosting device to meet both low and high-speed performance targets. One solution is to use two or more turbochargers of varied sizes. A smaller turbocharger provides boost at lower engine speeds, while a larger turbocharger has the flow capacity at higher engine speeds. The use of two boost devices may not be ideal owing to cost and packaging implications. Variable nozzle turbines (VNTs) are turbochargers that adjust their effective turbine size by adjusting internal flow paths; VNTs are appearing on light-duty gasoline engines [18]. VNT technology may permit the engine to operate with EGR and maintain peak performance with a single boosting device [21]. EPA does expect 48 V mild hybrid technology to become increasingly common as a greenhouse gas (GHG)reducing technology [22]. If 48 V is already available on a vehicle, there may still be low speed performance advantages to using an e-booster, particularly in truck or high-performance applications. Regarding fuel quality and autoignition, the predominant use of regular-grade, 87-88 anti-knock-index (AKI) gasoline in the U.S. must be considered for future studies into engine hardware. Autoignition occurs when low-temperature exothermic reactions occur in the unburned mixture end-gas. If the heat release is severe enough, and enough fuel is burned, then engine knock can occur. It is possible to reduce the likelihood of autoignition occurring by altering fuel chemistry. Premium-grade gasoline, typically 92 93 AKI in the U.S., has a higher resistance to autoignition and knock compared to regulargrade gasoline. Ignition retard is typically required to avoid engine knock at higher BMEP. Ignition retard offsets the combustion event to reduce heat addition. Retarding ignition timing reduces overall efficiency however by lowering the effective expansion ratio and reducing combustion efficiency. Therefore, to maintain a target load, more air must be inducted to permit additional fuel and maintain stoichiometric combustion. If a regular grade fuel is used, then additional combustion retard may be required, placing an additional requirement on the boosting system. When considering whether EGR is compatible with high CR, it is necessary to evaluate both regular and premium fuels to understand the boosting requirements. Experimental Setup The engine used in these experiments is based on a PSA1 EP6CDTX engine. It is a 4 cylinder, 1.6 L engine (Figure 1, Table 1) equipped with intake and exhaust cam phasing, continuously variable valve lift (CVVL) on the intake and a twin-scroll turbocharger with non-integrated, steel-cast exhaust manifold. The engine is equipped with a side-mounted injector located under the intake ports and normally operates with early injection timing fuel-air equivalence ratio (φ) of approximately 1.0. The relevant hardware characteristics of the engine are shown in Table 1. The operating ranges of the CVVL system and the dual cam-phasers are described in Figure 2. The parked position of the exhaust cam phaser yielded earliest exhaust phasing with the maximum valve lift location at 114° before top dead center (bTDC). The parked intake cam phaser position was set to provide latest intake cam phasing with the maximum valve lift location at 115° a

Predictive GT-Power Simulation for VNT Matching on a 1.6 L Turbocharged GDI Engine

GDI) engine [1]. Te model was tuned so that it predicted The thermal efciency benefts of low-pressure (LP) burn-rates and end-gas knock over an engine operating map exhaust gas recirculation (EGR) in spark-ignition with varying speeds, loads, EGR rates and fuel types. Using engine combustion are well known. One of the greatest the model, an assessment of VNT performance was performed barriers facing adoption of LP-EGR for high power-density using compressor and turbine maps made available from applications is the challenge of boosting. Variable nozzle Honeywell Transportation Systems. Results show that the turbines (VNTs) have recently been developed for gasoline single VNT device supports LP-EGR across the operating map applications operating at high exhaust gas temperatures while maintaining realistic full-load performance and main(EGTs). Te use of a single VNT as a boost device may provide taining or improving upon thermal efciency compared to a a lower-cost option compared to two-stage boosting systems twin-scroll turbocharger. Tis work was done as part of the or 48 V electronic boost devices for some LP-EGR applicaEnvironmental Protection Agency’s continuing assessment tions. A predictive model was created based on engine testing of advanced light-duty automotive technologies to support results from a 1.6 L turbocharged gasoline direct injection setting appropriate national greenhouse gas standards. Introduction By 2025, the automotive industry must reduce CO2 emissions by at least 30% and criteria pollutant emissions for vehicles sold in the U.S. by a factor of three [2]. To achieve these emissions standards, advanced engine combustion strategies are being pursued. One promising strategy is the use of cooled exhaust gas recirculation (EGR) [3, 4, 5, 6]. Cooled EGR leads to higher thermal efciencies through a reduction in heat transfer losses. Cooled EGR is also well known to improve knock resistance, enabling either higher compression ratios or increased specifc torque with optimal combustion phasing. Additionally, cooled EGR ofers benefts relative to specifc heat by displacing the diatomic air molecules with triatomic molecules recirculated from the exhaust. Te increase in heat capacity reduces combustion temperatures, leading to lower NOX and CO emissions [7]. Finally, pumping losses decrease with the use of cooled EGR by reducing the volumetric efciency of the engine and requiring higher manifold pressure for a given load. However, greater use of cooled EGR introduces a challenge in the sizing of traditional turbochargers. Te turbine in a traditional single-stage turbocharger is size-compromised to achieve the low-speed, high-load target as well as a high enough fow capacity for minimized turbine inlet pressure at the rated power condition. Te two performance targets require a design trade-of between lowand high-speed torque performance, resulting in a less than optimum turbine size for either condition. Variable nozzle turbines (VNTs) have the beneft of being able to adjust their turbine geometry to allow an efectively smaller turbine diameter at low speed (to achieve low-end torque) and an efectively larger turbine diameter at high speed (to achieve lower back pressure and high-power performance) [8, 9]. An added beneft of reduced exhaust back pressure at high engine loads is that it avoids the need for a wastegate. Tis reduction in exhaust backpressure is benefcial as it lowers the scavenging pressure ratio, which reduces the residual content in-cylinder and allows earlier combustion phasing and improved engine efciency [10]. Previous studies have shown the success of VNT with Miller operation. Tis paper identifes the potential of VNT to operate under dilute conditions, specifcally EGR dilution. Te purpose of this work was to develop an engine model using Gamma Technologies’ GT-Power sofware (Gamma Technologies, LLC., Westmont, IL) with a predictive combustion mechanism. Tis model assessed the performance of a VNT’s ability to support low pressure LP-EGR across the engine operating map and its impact on thermal efciency with varying EGR rates and fuel types. To accurately model 2 PREDICTIVE GT-PowER SIMULATIoN foR VNT MATChING oN A 1.6 L TURboChARGED GDI ENGINE This material is declared a work of the U.S. Government and is not subject to copyright protection in the United States. _L ________ _ Roots Supercharger F,..h Air FIGURE 1 EP6CDTx engine. FIGURE 2 Engine confguration as found in test-cell and as U S G ov er nm en t / U S En vi ro nm en ta l P ro te ct io n A ge nc y TABLE 1 PSA EP6CDTx Specifcations. modelled within GT-Power. boost is provided via stock, twin-scroll turbocharger and added positive displacement supercharger. The EGR valve is placed post-EGR cooler downstream of the turbine. U S G ov er nm en t / U S En vi ro nm en ta l P ro te ct io n A ge nc y Figure 2. While electrical power consumed by the supercharger electric motor was not included in the analysis, its operation and expected backpressure were included. Te exhaust manifold pressure was increased to match the intake manifold pressure to simulate a turbocharger capable of meeting the boost pressure requirement. For all simulated Displacement bore Stroke CR Turbocharger E-boost 1.6 L 77 mm 85.8 mm 10.5:1 original equipment twin-scroll or VNT boost cart with supercharger used. A schematic of the test cell setup can be found in Valve train Intake and Exhaust Cam Phaser Intake Valvetronic (Continuous VVL) Injection system Side-mounted GDI Rated Power 120 kw @ 5000 rpm Rated Torque 240 Nm @ 1600–4000 rpm U G ov er nm en t / U S En vi ro nm en ta l P ro te ct io n A ge nc y the efects of varying exhaust residuals, boost pressure and spark timing, a predictive, quasi-dimensional combustion model was constructed within GT-Power using data from an experimental version of a production PSA (Peugeot Société Anonyme) 1.6 L turbocharged engine shown in Figure 1 and Table 1. The output from the quasi-dimensional combustion model was used to investigate the efect of cooled EGR on inhibiting autoignition in a downsized turbocharged engine. In addition, further model data are presented demonstrating the capability of the model to predict boosting requirements correctly for a VNT or twin-scroll turbocharger at rated power.

Benchmarking a 2016 Honda Civic 1.5-liter L15B7 Turbocharged Engine and Evaluating the Future Efficiency Potential of Turbocharged Engines

As part of the U.S. Environmental Protection Agencys (EPAs) continuing assessment of advanced light-duty automotive technologies to support the setting of appropriate national greenhouse gas standards and to evaluate the impact of new technologies on in- use emissions, a 2016 Honda Civic with a 4-cylinder 1.5-liter L15B7 turbocharged engine and continuously variable transmission (CVT) was benchmarked. The test method involved installing the engine and its CVT in an engine dynamometer test cell with the engine wiring harness tethered to its vehicle parked outside the test cell. Engine and transmission torque, fuel flow, key engine temperatures and pressures, and onboard diagnostics (OBD)/CAN bus data were recorded. This paper documents the test results for idle, low, medium and high load engine operation, as well as motoring torque, wide-open throttle torque and fuel consumption during transient operation using both EPA Tier 2 and Tier 3 test fuels. Particular attention is given to characterizing enrichment control during high load engine operation. Results are used to create complete engine fuel consumption and efficiency maps and estimate CO2 emissions using EPAs ALPHA full vehicle simulation model, over regulatory drive cycles. The design and performance of the 1.5-liter Honda engine are compared to several other past, present, and future downsized-boosted engines and potential advancements are evaluated.