Automotive Powertrain Research Articles

Implementation of MCDM model in lean manufacturing using grey relational analysis in automotive industry

The present economic situation shows the consistent demand for profitable solutions that allow business organizations to gain better ad-vantage. Due to this reason, many organizations search for methodologies that allow them to improve their products and services improve their processes, reduce costs, and improve the profit and customer satisfaction. This has been implemented through lean techniques in their managerial and production methods. As we know Lean production system mainly emphasizes on the waste elimination, using simple and visual techniques. This paper is an attempt to optimize process layout and waste expulsion for automotive powertrain in a leading automo-tive company by using lean manufacturing techniques. In this paper, the existing process in place for machining of cam shaft is analysed and process layout is optimized to reduce cycle time and lead time. In order to reduce the cycle time, the process parameters such a speed, feed and depth of cut are optimized for increased material removal rate (MRR) and decreased surface roughness (RA) by using Grey Relational Analysis (GRA) technique. As MRR is inversely related to cycle time, optimization of parameters for higher MRR reduces the cycle time. Grey Relational Analysis is done by using Design Xpert software.

In-situ investigation of incipient melting in a 319 type Al alloy using laser scanning confocal microscopy

The modified 319 Al alloy system has been used extensively in precision sand casting of automotive powertrain applications such as engine blocks and cylinder heads, with significant improvement in vehicle fuel efficiency. However, a concern in elevated temperature processing of Al alloys, such as heat treatment and hot working processes, is incipient melting of secondary phases, which is deleterious to mechanical properties. In this study, the laser scanning confocal microscopy (LSCM) technique was used in the analysis of in-situ changes in microstructure as a result of incipient melting. Microstructural analysis was carried out prior to and following elevated temperature exposure in the LSCM using optical microscopy, SEM and EDX. The results suggest that incipient melting of the Al-Al2Cu-Al5Mg8Cu2Si6 ternary eutectic clusters was initiated by the formation of a liquid film which propagated rapidly from the eutectic clusters, coating the Al dendrites in regions adjacent to the eutectic clusters. Following film formation, the ternary eutectic clusters melted completely. Incipient melting also resulted in a localized change in composition in the interdendritic channels as supported by a change in cluster morphology from eutectic to a combination of coarse blocky Al-Cu-Ni and Si particles, and ultra-fine eutectic.

A Backlash Compensator for Drivability Improvement Via Real-Time Model Predictive Control

Nonlinear dynamics in the transmission and drive shafts of automotive powertrains, such as backlash, induce significant torque fluctuations at the wheels during tip-in and tip-out transients, deteriorating drivability. Several strategies are currently present in production vehicles to mitigate those effects. However, most of them are based on open-loop filtering of the driver torque demand, leading to sluggish acceleration performance. To improve the torque management algorithms for drivability and customer acceptability, the powertrain controller must be able to compensate for the wheel torque fluctuations without penalizing the vehicle response. This paper presents a novel backlash compensator for automotive drivetrain, realized via real-time model predictive control (MPC). Starting from a high-fidelity driveline model, the MPC-based compensator is designed to mitigate the drive shaft torque fluctuations by modifying the nominal spark timing during a backlash traverse event. Experimental tests were conducted with the compensator integrated into the engine electronic control unit (ECU) of a production passenger vehicle. Tip-in transients at low-gear conditions were considered to verify the ability of the compensator to reduce the torque overshoot when backlash crossing occurs.

Dry and minimum quantity lubrication high-throughput drilling of compacted graphite iron

ABSTRACTThis research studies the sustainable and high-throughput drilling of compacted graphite iron (CGI), a high strength, lightweight material for automotive powertrain applications. CGI drilling experiments were conducted using a 4 mm diameter coated carbide drill at 26.5 mm/s feed rate. In two repeated tests under three lubrication conditions: dry, dry with through-the-drill compressed air, and through-the-drill minimum quantity lubrication (MQL), the drills were able to produce a maximum of 1,740, 3,150 and 2,948 holes, respectively, before the breakage of the drill. The Joule–Thomson effect due to the expansion of high pressure air from through-the-drill holes at the drill tip, chip shape, chip size and chip speed are investigated. Flank wear of the drill cutting edge is measured and results are correlated to drill life. Results indicate that dry machining of CGI is technically feasible. Chip evacuation and advanced tool cooling are important factors that affect drill life for high-throughput sustainable dry drilling of CGI.

Stochastic Modeling and Diagnosis of Leak Areas for Surface Assembly

Assembly through mating a pair of machined surfaces plays a crucial role in many manufacturing processes such as automotive powertrain production, and the mating errors during the assembly (i.e., gaps between surfaces) can cause significant internal leakage and functional performance problems. The surface mating errors are difficult to diagnose because they are not measurable. Current in-plant quality control for surface mating focuses on controlling the surface flatness of each individual part before they are mated, and the mating errors are indirectly evaluated by a pressurized sealing test to check whether any pressure drop occurs. However, it does not provide any clue to engineers about the origins and the root cause of the internal leakage. To address these limitations, this paper presents a pressurized color-tracking method to directly measure internal leak areas. By using the measurements of leak areas and the profiles of surfaces mated as training data along with Hagen–Poiseuille law, this paper develops a novel diagnostic method to predict potential leak areas (leakage paths) given the measurements on the profiles of mating surfaces. The effectiveness and robustness of the proposed method are verified by a simulation study and an experiment. The approach provides practical guidance for the subsequent assembly process as well as troubleshooting in surface machining processes.

Speed Synchronization Control for Integrated Automotive Motor-Transmission Powertrains Over CAN Through a Co-Design Methodology

This paper deals with the speed synchronization controller design for networked integrated motor-transmission (IMT) powertrains via controller area network (CAN). It is well known that, in current implementations, CAN has been widely used in the control system design of automotive powertrains. However, on the other hand, the application of CAN would not only lead to network-induced delays but also bring about protocol constrains, e.g., data package capability and utilization ratio limitation, which would deteriorate the system and make the controller design a challenging problem. This paper is to provide a co-design methodology that can cope with all these problems and ensure satisfactory control effect for the speed synchronization control of IMT powertrain systems. First, a networked IMT powertrain system using CAN as underlying network is presented and the dynamic model for the speed synchronization control is derived. Second, the network-induced delay model is introduced and improved considering data packet capability and utilization ratio limitation. The control-orient discrete-time model is also derived based on the improved delay model. Third, a co-design methodology using sliding mode controller and offline priority scheduling based on Lyapunov stability criterion is proposed. The results of simulations and tests show the effectiveness of the proposed co-design methodology.

Impact of Duty Cycle on Wear Progression in Variable-displacement Vane Oil Pumps

Variable-displacement vane oil pumps are increasingly employed in automotive powertrains for their efficiency benefits through reduced losses. However, confirming long life reliability of a new commodity based on limited data available from product development tests and early field experience is a significant challenge, which is addressed by the work presented in this paper. The approach presented combines physical examination of pumps returned from tests, with analysis of damage factors for pump wear progression, and an analysis of functional parameters for the powertrain system focused on the cause effect linkages across the systems hierarchy. The metrology results from physical measurements of used parts provide useful insights for the wear progression and the expected service performance of the pump. The paper also expands towards a data driven approach based on ECU data analysis that could provide a pathway towards the development of online health monitoring and diagnostics of the oil pumps.

Challenges and solutions in automotive powertrain systems

Automotive powertrain mainly consisting of combustion engine, motor and battery (i.e. special for hybrid powertrain) is a very complicated integration system, and the research on the automotive powertrain control techniques remains hot-spot in past decades. This paper proposes some challenging issues and control solutions of automotive powertrain system from the perspective of the dynamic system theory. The typical characteristics of automotive powertrain system are analysed for control development, and the several control applications using model-based and model-free control design are demonstrated with sufficient experimental validation. In addition, some open issues for future powertrain control development are summarised.

Attempt to correlate simulations and measurements of turbine performance under pulsating flows for automotive turbochargers

The paper attempts to correlate simulations and measurements of turbine performance under pulsating flows for automotive turbochargers. Under real automotive powertrain conditions, turbochargers are subjected to pulsating flows, due to the motion of the engine’s valves. Experiments on a purpose-built 2.2 L diesel engine gas-stand have allowed the quantification of unsteady pulsating turbine performance. Temperature, pressure and mass flow measurements are fundamental for the characterisation of turbine performance. An adequate sampling frequency of the instruments and acquisition rates are highly important for the quantification of unsteady turbomachine performance. In the absence of fast, responsive sensors for monitoring mass flow and temperature, however, appropriate considerations would have to be taken into account when making estimates of turbine performance under pulsating flows. A 1D model of the engine gas-stand has been developed and validated against experimental data. A hybrid unsteady/quasi-steady turbine model has been adopted to identify unsteadiness at the turbine inlet and outlet. To evaluate isentropic turbine efficiency and reduce the influence of external heat transfer upon measurements, the turbine inlet temperature has been measured experimentally in the vicinity of the turbine rotor in the inlet section, upstream of the turbine tongue. The hybrid unsteady/quasi-steady turbine model considers the presence of unsteady flows in the turbine inlet and outlet, leaving the rest of the turbine to react quasi-steadily. Virtual sensors and thermocouples have been implemented in a 1D model to correlate experimental time-averaged temperature measurements.

Model based predictive engine torque control for improved drivability

Elasticity of the various driveline components and backlash originating from gear reduction mechanisms and fasteners may cause torsional vibrations resulting in unintended shunt and shuffle behaviours, when a vehicle is subjected to an acceleration change request. As a result of recent improvements to engine control structures and computational capability developments during the last few decades, the idea of using generated brake torque control has been considered a state of the art research topic among academic researchers and original equipment manufacturers (OEMs). In order to improve transient vehicle response to an acceleration change manoeuvre, a novel engine generated brake torque based model predictive control (MPC) algorithm with an additional anti-shuffle control element has been developed to manipulate the pedal map oriented torque demand signal in an automotive powertrain application. A four mass powertrain model was built and model validation considering longitudinal vehicle dynamics was performed with vehicle level tests using a tip-in followed by a tip out acceleration pedal signal input manoeuvre. Comparison of simulation results and vehicle test data shows that the proposed model is capable of capturing the vehicle acceleration profile revealing unintended error states for the specified input signals. MPC structures based on three mass vehicle models (derived from the four mass model via subtracting tyre dynamics due to high order nonlinearities at the tyre model) was developed in a “MATLAB/Simulink” environment to obtain a smooth and responsive acceleration profile. The MPC controller delivers signal states with the expected performance metrics without error states such as excessive jerks and shuffles. An additional engine to wheel speed difference based proportional controller is employed in order to further reduce powertrain oscillations without compromising from overall system response speed resulting in a comfortable drive.

Parameters design and braking efficiency analysis of a hydraulic self-energizing wedge disc brake

Pursuing more efficient running and operation has been the orientation of today's automotive powertrain and chassis technologies development. As for the brake system, increasing the braking efficiency or reducing the power consumption of actuation is an effective method to improve the energy-saving performance of the car. In this paper, a self-energizing wedge disc brake actuated by hydraulic power, that could be used to reduce both the actuation force and the energy required for braking is presented and compared in terms of the practical issues on braking efficiency, heat recession and self-locking. The selected critical parameters and their optimum value range are determined based on the static force analysis. Then the simulations based on AMESim/Simulink are implemented to compare the proposed wedge brake with traditional disc brake, and to investigate the influence of the wedge angle and the actuating angle on the braking efficiency performance. The simulation results validate the self-reinforcement and energy saving performance of this hydraulic wedge disc brake well.

Advanced deposition of hard a-C:Me coatings by HPPMS using Ne as process gas

Diamond-like carbon (DLC) coatings are used in numerous tribological applications, for example on highly-loaded components of the automotive powertrain. The high hardness and low roughness of these coatings contribute to the reduction of the component wear in tribological contact. It has been shown that hard a-C coatings with a low roughness can be deposited by means of high power pulsed magnetron sputtering (HPPMS) using Ne as process gas. Furthermore, the doping of a-C coatings with metals is the subject of current research. These a-C:Me coatings exhibit significant changes of the coating properties, which might contribute to a performance increase in tribological applications. Hence, in the present work a-C:Me coatings were successfully deposited in a high-volume semi-industrial coating unit by means of a hybrid process using one direct current magnetron sputtering cathode with a Zr target and one HPPMS cathode with a graphite target, using Ne as process gas. Furthermore, coatings were deposited using two HPPMS cathodes. The deposition of coatings using both types of processes was conducted in order to evaluate the influence of dcMS and HPPMS on the coating properties and the economic efficiency of both processes, respectively. The average power of the cathode with the Zr target was varied in the dcMS mode and in the HPPMS mode, whereas the cathode with the C target was powered constantly in HPPMS mode. A densification of the microstructure was observed for the HPPMS processes. Furthermore, different ratios of C and Zr in the coating were obtained, which resulted in a varying phase composition. Coatings with a maximum universal hardness HU=25GPa and arithmetic mean roughness Ra=0.03μm could be deposited.

Model-based design validation for advanced energy management strategies for electrified hybrid power trains using innovative vehicle hardware in the loop (VHIL) approach

Hybridization of automotive powertrains by using more than one type of energy converter is considered as an important step towards reducing fuel consumption and air pollutants. Specifically, the development of energy efficient, highly complex, alternative drive-train systems, in which the interactions of different energy converters play an important role, requires new design methods and processes. This paper discusses the inclusion of an alternative hybrid power train into an existing vehicle platform for maximum energy efficiency. The new proposed integrated Vehicle Hardware In-the-loop (VHiL) and Model Based Design (MBD) approach is utilized to evaluate the energy efficiency of electrified powertrain. In VHiL, a complete chassis system becomes an integrated part of the vehicle test bed. A complete conventional Internal Combustion Engine (ICE) powered vehicle is tested in roller bench test for the integration of energy efficient hybrid electric power train modules in closed-loop, real-time, feedback configuration. A model that is a replica of the test vehicle is executed – in real-time- where all hybrid power train modules are included. While the VHiL platform is controlling the signal exchange between the test bed automation software and the vehicle on-board controller, the road load exerted on the driving wheels is manipulated in closed –loop real-time manner in order to reflect all hybrid driving modes including: All Electric Range (AER), Electric Power Assist (EPA) and blended Modes (BM). Upon successful implementation of VHiL, a comparative study between Rule Based (RB) energy management strategy (EMS) and Equivalent Consumption Minimization Strategy (ECMS) to Control Parallel Through-The-Road Hybrid Electric Vehicle (PTTR-HEV) is performed. The study shows that the actual fuel efficiency of the tested vehicle under both control strategies can be used in order to evaluate the effectiveness of energy conversion efficiency of the powertrain system. The fuel consumption of hybridized powertrain is compared with the conventional powertrain equipped in an actual vehicle to help comprehend the degree of efficiency attained by the hybridization. This process is developed in order to enable effective tuning/validation of advanced energy management strategies utilized in hybrid electric powertrain through an evaluation of a complete real chassis system subject to electric hybridization. The VHiL is considered as new evolution for the utilization of vehicle test bed as a predictive mechatronic platform for the development of energy efficient electrified propulsion systems and thus reduce cost and time.

Balancing driveability, NVH, and fuel consumption on automotive powertrains using integrated simulation techniques

The engine downsizing approach can be considered as state-of-the-art automotive propulsion system. However, future trends are also indicating a trend to a further reduction of the number of engine architectures, normally accompanied with a reduction of the number of cylinders in internal combustion engines, including prospective use of alternative fuels such as compressed natural gas or the downsized engine embedded in a powertrain with electrically driven propulsion systems. Hitherto, different simulation approaches are employed to evaluate the trade-off between noise, vibration and harshness, driveability, and fuel consumption. This paper presents the coupling of two simulation tools, each one an established tool in its discipline, namely a 1D-gas-dynamics tool for a downsized internal combustion engine including a dedicated boost-pressure control approach, and a multibody dynamics tool to simulate the powertrain and vehicle dynamics, using the functional mock-up interface. Using this approach as an industry first application, a significant reduction of development time while avoiding duplication of powertrain subsystem modeling, is achieved. This enables a transient simulation and supports a fast analysis of different powertrain architectures. It, furthermore, allows a detailed look at the impact of powertrain subsystems like the architecture of the internal combustion engine, flywheel, and driveline design on relevant vehicle attributes. Moreover, the transient simulation approach allows the investigation of lag effects caused by the air-path characteristics of the internal combustion engine, or transient effects brought up with the advent of hybrid powertrain architectures. The application case of this tool chain presented in this paper revealed that engine architecture reduction should be carried out carefully in order to not compromise driveability of the engine later on. This could bear the risk of sacrificing fuel economy due to a higher lugging limit, often linked to a reduced firing order of the engine, caused by a reduction of the number of cylinders. The paper finally discusses prospective solutions in terms of conventional mechanical solutions and added electrified propulsion including potential limitations to overcome this issue.

Simulation based optimization of torsional vibration dampers in automotive powertrains

In this paper, an approach for the automated design of isolation elements as used in automotive powertrains is presented. The method is based on 1D-MBS models representing various drivetrain configurations and damper concepts. This allows for a dynamical analysis in typical design relevant driving situations like full load acceleration or engine start. The concept design is carried out in a numerical optimization process in order to find a set of geometric parameters with minimal design space requirements and weight. Especially the specifications imposed on the drivetrain’s vibrational behavior lead to a complex optimization problem which requires robust and carefully tuned algorithms. A search method that has been successfully applied to constrained design problems in engineering is the Augmented Lagrangian Particle Swarm Optimization procedure. The dimensioning of a dual mass flywheel with an additional internal damper for an all-wheel drive sports car is used as a test case to evaluate the algorithm’s suitability for this particular application. Several control parameter settings are compared regarding their influence on the optimizer performance.

Simulation-Based Computational Design Synthesis Using Automated Generation of Simulation Models From Concept Model Graphs

Current approaches in computational design synthesis (CDS) enable the human designer to explore large solution spaces for engineering design problems. To extend this to support designers in embodiment and detail design, not only the generation of solution spaces is needed but also the automated evaluation of engineering performance. Here, simulation methods can be used effectively to predict the behavior of a product. This paper builds on a general approach to automatically generate solution spaces for energy and signal-based engineering design tasks using first-order logic and Boolean satisfiability. The generated concept model graphs (CMGs) are now in this paper automatically transformed into corresponding bond-graph-based simulation models. To do this, guidelines for creating partial simulation models for the available synthesis building blocks are presented. The guidelines ensure valid causality in the final simulation model. Considering the connections in the concept model graphs, the simulation models are automatically generated and simulated. The simulation results are then used to calculate different objectives, constraints, and performance metrics. The method is validated using automotive powertrains as a case study. One hundred and sixty-two different powertrain concepts are generated and evaluated, showing the advantages of electric powertrains with respect to CO2 emissions and the importance of considering intelligent control strategies in the future for hybrid ones.

Production planning in automotive powertrain plants: a case study

Based on a real case study from the automotive industry, this paper deals with production planning in powertrain plants. We present an overview of the production planning process and propose a mixed integer linear programme to determine the production quantities of each product over a planning horizon of several days. Then, using real data of an engine assembly line, we simulate the performance obtained through the proposed model within a rolling horizon planning process. We perform multiple tests in order to evaluate the impact of two parameters involved in this process: planning frequency and frozen horizon length. Furthermore, in order to illustrate the value of improving coordination between engine plants and their customers, we evaluate the impact of the quality of demand information (orders and forecasts). We analyse the simulation results and provide insights and recommendations in order to achieve a good trade-off between service level, inventory, and planning stability.

A Study on Dynamic Vibration Design of Lightweight Aluminum Drive Shaft for Automotive Powertrain

In this study, we changed the existing S45C steel shafts applied to the drive shaft for power train of automotive to Al7003-T6 aluminum material. For this purpose, the optimal inner diameter of the aluminium shaft is established. And, analysis of the stresses and vibration characteristics of shafts were analyzed through finite element analysis. The final aluminum drive shaft was evaluated through the static torsional torque test and the frequency test. The Al7003-T6 aluminum drive shaft's weight is 67% comparing from 100% of shaft with existing steel, and with the performance of 3,276 N-m and 236 Hz, it satisfies requirements of the torsional torque of 3,000 N-m and vibration characteristic over 150 Hz required for drive shaft.

Electrified Automotive Powertrain Architecture Using Composite DC–DC Converters

In a hybrid or electric vehicle powertrain, a boost dc–dc converter enables reduction of the size of the electric machine and optimization of the battery system. Design of the powertrain boost converter is challenging because the converter must be rated at high peak power, while efficiency at medium-to-light load is critical for the vehicle system performance. By addressing only some of the loss mechanisms, previously proposed efficiency improvement approaches offer limited improvements in size, cost, and efficiency tradeoffs. This paper shows how all dominant loss mechanisms in automotive powertrain applications can be mitigated using a new boost composite converter approach. In the composite dc–dc architecture, the loss mechanisms associated with indirect power conversion are addressed explicitly, resulting in fundamental efficiency improvements over wide ranges of operating conditions. Several composite converter topologies are presented and compared to state-of-the-art boost converter technologies. It is found that the selected boost composite converter results in a decrease in the total loss by a factor of 2–4 for typical drive cycles. Furthermore, the total system capacitor power rating and energy rating are substantially reduced, which implies potentials for significant reductions in system size and cost.

Selection of Electrification Technologies of Automotive Powertrains and Uncertainty Management Strategy

Selection of Electrification Technologies of Automotive Powertrains and Uncertainty Management Strategy