Automotive Powertrain Research Articles

Application of Evolutionary Computation in Automotive Powertrain Mount Tuning

Engine mount tuning is a multi‐disciplinary exercise since it affects Idle‐shake, Road‐shake and power‐train noise response. Engine inertia is often used as a tuned absorber for controlling suspension resonance related road‐shake issues. Last but not least, vehicle ride and handling may also be affected by mount tuning. In this work, Torque‐Roll‐Axis (TRA) decoupling of the rigid powertrain was used as a starting point for mount tuning. Nodal point of flexible powertrain bending was used to define the envelop for transmission mount locations. The frequency corresponding to the decoupled roll mode of the rigid powertrain was then adjusted for idle‐shake and road‐shake response management.A TRA decoupling procedure, cast as a multi‐objective optimization problem, was applied to a body‐on‐frame sport‐utility vehicle powertrain system. In addition to a standard gradient based optimization algorithm, available in commercial finite element software, an evolutionary computation paradigm known as Evolutionary Strategies (ES) was used to solve the optimization problem. The primary advantages of evolutionary computation over gradient based algorithms are as follows: i) They are less likely to get trapped in local minima and less dependent on initial values of the design parameters and therefore able to handle multi‐modal optimization problems unlike gradient based algorithms, ii) They produce a population of viable solutions, unlike gradient based algorithms which yields a single solution. The second advantage is very attractive in a production environment since packaging and other multi‐disciplinary constraints often require multiple quality solutions for the same problem. The process outlined in this work was verified by exercising a full‐vehicle finite element model. The process produced a set of production feasible powertrain mount parameters for acceptable idle and road shake performance.

3D Finite Element Analysis Of A Hydraulic EngineMount Including Fluid-structure Interaction

The interaction between fluid and structure can, in many practical engineering problems, significantly affect the response of the structures and hence needs to be properly taken into account in the analysis. Fluid-structure coupling and the finite element method are used in this paper to propose a new strategy to analyze the dynamic behaviour of the hydraulic engine mount (HEM) that is now widely used as a highly effective vibration isolator in the automotive power-train. The work conducted in this paper demonstrates that the proposed method for estimating the system parameters using the FSI for modeling the HEM is effective and the dynamic characteristics of the HEM can be performed before its prototype development, and this can ensure its low cost and high quality for development.

Dynamics and control of gearshifts on twin-clutch transmissions

Based on a detailed dynamic model of an automotive powertrain containing a twin-clutch transmission, an integrated powertrain control for gearshifts is developed. The operation of this controller is demonstrated on the basis of simulation results for upshifts, downshifts, and multiple gearshifts taking place within the same half of the transmission. The control algorithm makes use of closed-loop control of clutch slip for a smooth transfer of engine torque with the aim of reproducing the operation of a one-way clutch. Further elements are a closed-loop control of engine speed through a combination of a manipulation of engine controls and clutch pressure. In addition, it is demonstrated that the control of transmission output torque during gearshifts can add robustness to the control and provides a means to manipulate directly the gearshift character. Finally, the dynamic effects of gear preselection through conventional hydraulically actuated cone-type synchronizers on the overall shift quality are discussed.

Moisture Effects on Mechanical Performance of Laser-welded Polyamide

Basic experimental investigations, in our case of polyamide at ‘dry-as-molded conditions’, include optical examination and mechanical performance for through transmission laser welding technology. Recent developments on laser welding of thermoplastics for automotive powertrain applications have discussed the influence of accumulated moisture on the optical and mechanical characteristics of laser welded polyamide. Results from this report provide supporting data that moisture in polyamides is not a barrier for laser welding applications, nor is detrimental for the mechanical performance of welded parts in automotive powertrain applications. Laser welding would be able to satisfy and support the basic demands of the mechanical performance of welded polyamide at various environmental and manufacturing conditions. This can only be achieved at optimized processing and weld design conditions.

Additives 2005: Optimising Automotive Power Trains

Additives 2005: Optimising Automotive Power Trains

MODEL PREDICTIVE CONTROL OF AUTOMOTIVE POWERTRAINS WITH BACKLASH

In automotive powertrains, the existence of backlash causes driveability problems, which to some extent are remedied by the engine control system. The control problem has a constrained, minimum-time character, which motivates an investigation of the usability of model predictive control, MPC, in this application. Recent developments in MPC theory make an off-line calculation of the control law possible. This makes MPC more attractive for implementation in fast control loops such as the one under study here. The results indicate that MPC has a potential in this application. However, the off-line computation time is significant, and further robustness investigations are needed.

ACTUAL ENGAGED GEAR IDENTIFICATION: A HYBRID OBSERVER APPROACH

The knowledge of the actual engaged gear is essential to achieve high-quality control of an automotive power train. In cars equipped with manual gear shift, this information is not directly available. A hybrid observer for on-line identification of the actual engaged gear is proposed. Two hybrid models of an automotive driveline, a detailed one for verification and a reduced-order one for synthesis, have been developed. The identification algorithm is based on a novel approach to observer design for hybrid systems. The algorithm was tested on experimental data obtained at Magneti Marelli Powertrain on an Opel Astra equipped with a Diesel engine and a robotized gearbox and yielded excellent results.

NICELY NONLINEAR ENGINE TORQUE ESTIMATOR

In automotive powertrain control strategy, engine torque estimators are preferred to expensive sensors for obvious economic reasons. In the literature several works have been presented proposing both instantaneous engine torque and mean engine torque estimators. The first ones are based on complex models and tipically are suitable for diagnosis purposes, while the latter estimate the torque by means of static maps. In this work, a nonlinear torque estimator for a spark ignition engine has been developed. The total torque acting at the engine shaft has been obtained solving a tracking problem by means of an LQ control strategy. The novel idea is to reduce the nonlinear engine model to a second order Taylor approximation, named a nicely nonlinear model. It is then linearized via feedback and an LQ controller is designed. This approach has been tested on Mid-Size real time dSPACE simulator showing excellent results both for performance and for computational load.

Novel Polymer Electrolyte Membranes for Automotive Applications – Requirements and Benefits

AbstractDuring the past few years, the feasibility of using polymer electrolyte fuel cells in automotive power trains at an impressive performance level has been proven repeatedly. However, current fuel cell stacks are still largely based on decade‐old polymer electrolyte membrane technology thus limiting performance, durability, reliability, and cost of the fuel cell systems. The major challenge for membrane R&D constitutes the demand for polymer electrolytes that allow for system operation at higher temperatures and lower water management requirements without increased conduction losses. None the less, demanding automotive requirements will not compromise on other properties such as mechanical and chemical stability and gas permeability.

Analysis and simulation of clutch engagement judder and stick-slip in automotive powertrain systems

Clutch engagement judder and stick—slip are investigated analytically and numerically to examine the influencing factors on these phenomena. Models are developed for a four degree-of- freedom (4DOF) torsional system with slipping clutch and for a powertrain with automatic transmission system. Stability analysis is performed to demonstrate that clutch judder is dependent on the slope of the friction coefficient and the analysis is verified with numerical simulations. An algorithm for modelling stick—slip is developed and is used in numerical simulations which show that the likelihood of stick—slip is increased by clutch pressure fluctuations, judder approaching engagement, and external torque fluctuations. Numerical simulations for second to third gear up shifts demonstrate that the likelihood of stick—slip to occur from clutch engagement is increased by clutch applied pressure fluctuations, judder approaching engagement, and external torque fluctuations and that the likelihood of stick—slip occurring is decreased dramatically by applied pressure ramps proximus to the engagement point.

Estimating the cost of a new technology intensive automotive product: A case study approach

Estimating cost of new technology intensive products is very ad hoc within the automotive industry. There is a need to develop a systematic approach to the cost estimating, which will make the estimates more realistic. This research proposes a methodology that uses parametric, analogy and detailed estimating techniques to enable a cost to be built for an automotive powertrain product with a high content of new technology. The research defines a process for segregating new or emerging technologies from current technologies to enable the various costing techniques to be utilised. The cost drivers from an internal combustion engine's characteristics to facilitate a cost estimate for high-volume production are also presented. A process to enable a costing expert to either build an estimate for the new technology under analysis or use a comparator and then develop a variant for the new system is also discussed. Due to the open nature of the statement ‘new technology’, research is also conducted to provide a meaningful definition applicable to the automotive industry and this project.

Development of a Friction Component Model for Automotive Powertrain System Analysis and Shift Controller Design based on Parallel-Modulated Neural Networks

In this study, a new hybrid-neural-network-based friction component model is developed for powertrain (PT) dynamic analysis and controller design. This new model, with significantly improved input-output scalability over conventional neural network configuration, has the capability to serve as a forward as well as an inverse system model. The structural information of the available physical and empirical correlations is utilized to construct a parallel-modulated neural network (PMNN) architecture consisting of small parallel sub-networks reflecting specific mechanisms of the friction component engagement process. The PMNN friction component model isolates the contribution of engagement pressure on engagement torque while identifying the nonlinear characteristics of the pressure-torque correlation. Furthermore, it provides a simple torque formula that is scalable with respect to engagement pressure. The network is successfully trained, tested and analyzed, first using analytical data at the component level and then using experimental data measured in a transmission system. The PMNN friction component model, together with a comprehensive powertrain model, is implemented to simulate the shifting process of an automatic transmission (AT) system under various operating conditions. Simulation results demonstrate that the PMNN model can be effectively applied as a part of powertrain system model to accurately predict transmission shift dynamics. A pressure-profiling scheme using a quadratic polynomial pressure-torque relationship of the PMNN model is developed for transmission shift controller design. The results illustrate that the proposed pressure profiling technique can be applied to a wide range of operating conditions. This study demonstrates the potential of the PMNN architecture as a new dynamic system-modeling concept: It not only outperforms the conventional network modeling techniques in accuracy and numerical efficiency, but also provides a new tool for transmission controller design to improve shift quality.

Automotive tribology overview of current advances and challenges for the future

This keynote address will provide a comprehensive overview of various lubrication aspects of a typical powertrain system including the engine, transmission, driveline, and other components, as well as the integration of these lubrication and surface engineering concepts into a unified automotive powertrain system. In addition, this presentation will focus on the current status and future trends in automotive lubricants including discussion of current and anticipated future requirements of automotive engine oils. This presentation will also review the current standard ASTM (American Society for Testing and Materials) test methods for engine lubricants and other compilations of automotive standards. In addition to engine oil test development, industrial researchers are developing light-weight materials such as non-ferrous materials (Al, Mg) for engine and drivetrain materials to replace the current heavy-weight cast iron blocks. Recent industrial developments include high strength and high density of composite materials, high volume liquid molding and hydroforming technology, structural adhesive boding, and the ability to mold large structural components. Industrial researchers have also developed processing improvements for forming more complex stamped aluminum parts or panels, more robust stamping, and improved casting techniques. In this paper, our insights and perspectives on future trends in light-weight tribological material and nonotribology will also be reviewed.

Estimation of Backlash in Automotive Powertrains — An Experimental Validation

In automotive powertrains, backlash imposes well-known limitations on the quality of control and hence the driveability. In order to increase the controller performance, knowledge of the backlash properties (size and current position) is needed. In previous papers, nonlinear estimators for backlash size and position are described, based on Kalman filtering theory. The size and position estimators are combined, and the result is an estimate of the state of the backlash. In this paper, experimental results from vehicle tests show that the estimates are of high quality, and hence useful for improving backlash compensation functions in the powertrain control system.

Nonlinear Thermal Modelling of an Electrical Supercharger

The model described in this paper is utilised for the estimation of component temperatures of a motor operating in an electrical boost device (EBD) within an automotive powertrain environment. Due to the interacting electrical and mechanical characteristics of this device, the energy dissipated in the form of heat is modelled as a nonlinear feature. The primary purpose of this model is to provide a sensorless temperature inference mechanism whereby the overall cost of the unit can be brought down and the control of the motor can be constrained to its thermal limits.

Damping and Mechanical Properties of (Graphite + 9Al<sub>2</sub>O<sub>3</sub>·2B<sub>2</sub>O<sub>3</sub>)/Mg Metal Matrix Composites

Mg alloys have potential to use automotive parts because of their weight and castability. High temperature strength and damping capacity is important to the automotive power train parts. Mg alloy has lower creep and thermal fatique strength but has better damping capacity than Al alloy. It is known that short fiber reinforced Mg metal matrix composites(MMC) exhibits superior high temperature strength and graphite reinforced Mg MMC shows excellent damping capacity. Therefore, in this study, the effect of graphite particles(15-25%) and alborex (9Al2O3ּ2B2O3) whiskers(5-15%) on the damping behavior and mechanical properties of Mg MMC was studied. Graphite particles and alborex whiskers were chosen to increase damping capacity and high temperature strength, respectively. The Mg MMC was fabricated by squeeze casting and the total quantity of reinforcements(graphite + alborex) was maintained to 30 volume percent. The damping capacity of the metal matrix composites was increased and the flexural strength and hardness were decreased with increasing the volume fraction of graphite particles, that is, reducing the volume fraction of alborex whiskers.

Robotic Vision Systems selected for worldwide automotive power train traceability program

Robotic Vision Systems selected for worldwide automotive power train traceability program

Automotive Power-train towards the Sustainable Development : Does hybridization enable ICE vehicles to compete in the future?

Here in the 21^<st> century, there exist many environmental and natural resource problems such as global warming, fossil fuels resources, and air pollution in urban areas that must be addressed by the automobile industry. The internal combustion engine and electric motor hybrid and fuel cell hybrid vehicles are thought as influential candidates for next generation vehicles to challenge these issues. This paper describes the evolution of ICE vehicles by applying hybrid technology and reports the current status and issues of the ICE hybrid vehicles in the market. With the achievements of this technology that means in combination of advanced ICE and electric drive technologies, I would like to discuss the future potential of ICE vehicles that allow to continue to play an important role in the future.

Analysis of Short Life Flaking due to Hydrogen Embrittlement (Influence of Micro Slip on Flaking due to Hydrogen Embrittlement)

Bearings used for automotive powertrains sometimes suffer flaking damage that unexpectedly shortens their life due to peculiar microstructural changes at their subsurface. In this paper, based on various experiments and calculations, we describe the cause of such flaking. The experimental results suggest that this flaking is a kind of hydrogen embrittlement caused by the diffusion of hydrogen into the steel due to the decomposition of the lubricant, and that in affected by the amount of relative slip ratio between ball and bearing race.

Creep Resistant Magnesium Alloys for Powertrain Applications

AbstractCreep resistant magnesium alloys are candidate materials for automotive powertrain applications. Since the 90's, a number of new creep‐resistant magnesium alloy systems have been investigated and developed. These are for the most part based on rare‐earth, alkaline earth, and silicon additions. This paper gives an overview of creep resistance in magnesium and a review of creep resistant magnesium alloys for power‐train applications.