Advanced propulsion system for hybrid vehicles

A number of hybrid propulsion systems were evaluated for application in several different vehicle sizes. A conceptual design was prepared for the most promising configuration. Various system configurations were parametrically evaluated and compared, design tradeoffs performed, and a conceptual design produced. Fifteen vehicle/propulsion systems concepts were parametrically evaluated to select two systems and one vehicle for detailed design tradeoff studies. A single hybrid propulsion system concept and vehicle (five passenger family sedan)were selected for optimization based on the results of the tradeoff studies. The final propulsion system consists of a 65 kW spark-ignition heat engine, a mechanical continuously variable traction transmission, a 20 kW permanent magnet axial-gap traction motor, a variable frequency inverter, a 386 kg lead-acid improved state-of-the-art battery, and a transaxle. The system was configured with a parallel power path between the heat engine and battery. It has two automatic operational modes: electric mode and heat engine mode. Power is always shared between the heat engine and battery during acceleration periods. In both modes, regenerative braking energy is absorbed by the battery

Study of power quality assessment for a photo-voltaic based Distribution Static Compensator (DSTATCOM)

This thesis presents an idea of PV cell or battery based dc to dc boost converter which is served to a voltage source converter (VSC) for enhancement of quality of power. A synchronous reference controller is suggested using distribution static compensator (DSTATCOM) in a 3-phase 4-wire transmission system. The DSTATCOM mainly comprises of one VSC and a dc-link capacitor. The main purpose of DSTATCOM is to provide source and total harmonic reduction, reactive power compensation and compensation of neutral current at point of common coupling .A PCC is a point on electricity network where consumer loads are connected. The boost converter used does the work of a chopper. It converts variable output dc to a fixed value of dc by stepping up of voltage equal to the DC-link necessity of voltage source converter. The main benefit of this planned scheme is that, it will always deliver continual compensation for the whole day. To provide separation to voltage source converter and path for fundamental of zero sequence components, one star/delta transformer is employed. It also helps to diminish neutral current by supplying a circulating route in secondary winding of transformer which is delta connected. The required gate pulse to IGBT’s and diode are provided from the PWM controller by using synchronous reference algorithm

Proposed exergetic based leak detection and diagnosis methodology for automotive carbon dioxide air conditioning systems

Due to the overwhelming concern of global warming and ozone depletion, the replacement of many currently used refrigerants is a pressing matter within all sectors of refrigeration. Presently, the hydroflourocarbon (HFC) 134a, the working fluid of automotive air conditioning (AC) systems, greatly contributes to global warming as the result of system leakage. Both chemical and natural refrigerant losses impose threats to the environment and human health as well as reduce operational efficiency which increases energy consumption. If no action is taken to replace the chemical refrigerants, then it is proposed that the emissions from fluorinated gasses would increase from 65.2 million tons of carbon dioxide (the value found in 1995) to 98 million tons by 2010 [EurActiv.com 2004]. Natural refrigerants have gained worldwide attention as the logical replacement for chemical refrigerants. Carbon dioxide (CO2) is the natural refrigerant receiving the most attention due to its abundance in nature. When deciding to replace a refrigerant worldwide, many factors are taken under consideration. The benefits and necessary changes that occur when using CO2 as the working fluid are explored. One important aspect of using CO2 as a replacement refrigerant in automotive AC systems lies in diagnosing refrigerant leakage within a faulty system. A reliable and easy to use refrigerant leakage detection and diagnosis system is a necessity for automotive mechanics. In current research at RIT, advanced thermodynamics is being used to develop a fault detection and diagnosis system specifically for the future CO2 automotive AC systems. A simulation of the automotive air conditioning system using the software program Engineering Equation Solver (EES) is developed to simulate normal and faulty operation of the AC system. The model incorporates an exergetic analysis which combines the conservation of mass and conservation of energy laws with the second law of Thermodynamics. Fundamental laws of thermodynamics are used to verify data provided by past work [McEnaney 1999] obtained during normal operation. Using the EES model, refrigerant losses are simulated throughout the system one at a time at locations prone to leakage and the model produces a faulty operating data library. Analyzing the simulated fault data for possible trends or patterns is done in order to detect future system faults and to diagnose the faults accordingly. Trends are produced from the faulty data and are shown in graphical form. It is possible to detect and diagnose leaks by looking at the trends for a component where leaks are not even occurring

Human-Robot Collaboration in Automotive Industry

Human–Robot Collaboration is a new trend in the field of industrial and service. Application of human-robot-collaboration techniques in automotive industries has many advantages on productivity, production quality and workers’ ergonomic; however, workers’ safety aspects play the vital role during this collaboration. Previously, the machine is allowed to be at automatic work only if operators are out of its workspace but today collaborative robots provide the opportunity to establish the human robot cooperation. In this thesis, efforts have been made to present innovative solutions for using human-robot collaboration to develop a manufacturing cell. These solutions are not only used to facilitate the operator working with collaborative robots but also consider the worker safety and ergonomic. After proposing different solutions for improving the safety of operations during the collaboration with industrial robots, the efficiency of the solutions is tested in both laboratory and virtual environments. In this research, firstly, Analytic Hierarchy Process (AHP) has been used as a potential decision maker to prove the efficiency of human-robot collaboration system over the manual one. In the second step, detailed task decomposition has been done using Hierarchical Task Analysis (HTA) to allocate operational tasks to human and robot reducing the chance of duty interference. In the International Organization of Standardization's technical specification 15066 on collaborative robot safety four methodologies have been proposed to reduce the risk of injury in the work area. The four methods implied in ISO/TS 15066 are safety-rated monitored stop (SMS), hand-guided (HG), speed and separation monitoring (SSM) and power force limiting (PFL). SMS method reduces the risk of operator’s injury by stopping the robot motion whenever the operator is in the collaborative workspace. HG method reduces the chance of operator’s injury by providing the possibility of having control over the robot motion at all times in the workstation using emergency system or enabling device. The SSM method determines the minimum protective distance between a robot and an operator in the collaborative workspace, below which the robot will stop any kind of motion and PFL method reduces the momentum of a robot in a way that contact between an operator and the robot will not cause any injury. After determining the requirements and specifications of hybrid assembly cell, few of the above-mentioned methods for evaluating the safety of human-robot-collaboration procedure have been tasted in the laboratory environment. Due to the lack of safety camera (sensors) in the laboratory workstation, the ISO methods such as SSM, that needs sensors in the workstation, have been modeled in virtual environment to evaluate different scenario of human-robot-interaction and feasibility of the assembly process. Implementing different scenarios of ISO methods in hybrid assembly workstation not only improves the operator safety who is in interaction with the collaborative robot but also improves the worker ergonomic during the performing of repetitive heavy tasks

Study of process parameters towards improving efficiency of closed die hot forging process

Closed die hot forging process is one of the most adopted methods for forming complex shaped parts with satisfactory geometrical accuracy. Over sixty percent of the forgings are processed through this route. Forged parts, though required in many engineering sectors, play a vital role in the automotive sector. The majority of the crucial load bearing structural components as well as safety critical items are processed via the forging route. This is mainly due to the inherent strength to weight ratio and dimensional accuracy that can be combined into the components. Faster production of complex shapes with least wastage of material are some of the other benefits. The metal flow analysis of the process is complex due to the involvement of a large number of parameters. A number of experimental testings and production-trials are being done in the industry in order to develop a robust manufacturing process. Such practices however involve huge investments in tooling and raw materials, including a great deal of development time and effort. In recent years, finite element method has emerged as a suitable tool for virtual process trials and simulation based design. This would lead to an improvement in overall efficiency of the process at a lower cost. Through the present study, an attempt has been made to gain an insight into the process parameters influencing the closed die hot forging and their interaction. As a sample case, a real life automotive driveline component, a flange yoke, is taken for investigation. A simulation-driven approach using a commercial package (DEFORM), based on finite element method, was adopted. Trials were conducted using an industrial press, data generated were validated against those predicted. The correlation was found to be satisfactory

Modeling and experimental identification of drill string torsional dynamics under uncertainties

This D.Sc. thesis proposes new perspectives for modeling drill string torsional dynamics under uncertainties. This work develops a novel stochastic hysteretic (nonreversible) bit-rock interaction model. Firstly, a new nominal interaction model, which depends not only on the bit speed, but also on the bit acceleration is developed. Then, a new stochastic model for the bit-rock interaction, taking into account the inherent fluctuations during the drilling, is also proposed. Furthermore, a new test-rig is proposed to analyze drill string dynamics and bit-rock interaction, which is able to reproduce stick-slip phenomena while drilling a rock sample using standard masonry bits, as well as to validate bit-rock interaction models. An original strategy for modeling uncertainties globally, based on terms of the nonparametric probabilistic approach, considering a simple torsional model for a drill string, is also proposed. This strategy allows to control the dispersion level of each interior and interface DOFs of each drill string substructure independently, which can provide more information to improve the operational safety.Esta tese de doutorado propõe novas formas de modelar a dinâmica torciona de uma coluna de perfuração de petróleo considerando incertezas. Este trabalho propõe um novo modelo estocástico de interação broca-rocha histerético (não-reversível). Primeiramente, um novo modelo nominal de interação o qual depende não somente da velocidade angular da broca, mas também de sua aceleração é proposto. Então, um novo modelo estocástico para a interação broca-rocha levando em consideração as flutuações inerentes é também proposto. Além disso, uma nova bancada experimental é proposta para analisar a dinâmica da coluna de perfuração de petróleo e interação broca-rocha, a qual é apta para reproduzir o fenômeno do stick-slip enquanto perfura uma amostra de rocha utilizando broca de concreto comercial, assim como validar modelos de interação broca-rocha Uma estratégia original para modelar incertezas em nível global baseada em termos da abordagem probabilística não-paramétrica considerando um modelo torcional simples para uma coluna de perfuração de petróleo é também proposta. Esta estratégia permite controlar o nível de dispersão para cada grau de liberdade interno e na interface de cada subestrutura de forma independente, a qual pode prover mais informações para melhorar a segurança operacional

Design and Optimization of Dynamic System for a One-kW Free Piston Linear Engine Alternator-GENSETS Program

In power/energy systems, free-piston linear machines are referred to as a mechanism where the constrained crank motion is eliminated and replaced with free reciprocating piston motion. Depending on the application, the piston motion can be converted into other types of energy and includes compressed air/fluid, electricity, and high temperature/pressure gas. A research group at West Virginia University developed a free-piston linear engine alternator (LEA) in 1998 and have achieved significant accomplishment in the performance enhancement of the LEAs to date. The present LEA design incorporates flexure springs as energy restoration components and as bearing supports. The advantages of using flexure springs are threefold and include: (1) it increases the LEA’s stiffness and resonant frequency, and hence the power density; (2) it eliminates the need for rotary or linear bearings and lubrication system; and (3) it reduces the overall frictional contact area in the translator assembly which improves the durability. The current research focuses on the design and optimization of the flexure springs as the system’s resonant dominating component for a 1 kW free-piston LEA. First, the flexure springs were characterized according to the LEA’s target outputs and dimensional limitations. The finite element method (FEM) was used to analyze the stress/strain, different modes of deformation, and fatigue life of a range of flexure spring designs under dynamic loadings. Primary geometric design variables included the number of arms, inside and outside diameter, thickness, and arm’s length. To find the near-optimum designs, a machine learning algorithm incorporating the FEM results was used in order to find the sensitivity of the target outputs to the geometrical parameters. From the results, design charts were extracted as a guideline to flexure spring selection for a range of operations. Then, methods were introduced, investigated, and analyzed to improve the overall energy conversion performance and service life of the flexure springs and the overall LEA system. These included: a transient FE tool used for fatigue analysis to quantify the life and factors of safety of the flexure springs as well as the spring’s hysteresis; a fluid/structure interaction model used to quantify the energy loss due to drag force applied on the flexures’ side surfaces; packaging of multiple flexures to increase the overall stiffness and to reduce the vibration-induced stresses on flexure arms due to higher harmonics; a model to investigate the two-way interactions of the flexures’ dynamics with the alternator and engine components to find an optimum selection of the LEA’s assembly; a non-linear friction analysis to identify/quantify the energy losses due to the friction of the sliding surfaces of the flexures and spacers; and a series of static and transient experiment to determine the non-linearity of flexures’ stiffness and comparison to FEM results and for validation of the energy audit results from numerical and analytical calculations. With over 6000 flexure designs evaluated using artificial intelligent methods, the maximum achievable resonant frequency of a single flexure spring for a 1 kW LEA was found to be around 150 Hz. From the FEM results, it was found that under dynamic conditions the stress levels to be as high as twice the maximum stress under static (or very low speed) conditions. Modifications of the arm’s end shape and implementation of a shape factor were found as effective methods to reduce the maximum stress by 20%. The modal analysis showed that the most damaging modes of deformations of a flexure spring were the second to fourth modes, depending on the number of arms and symmetry of the design. Experiment and FEM results showed that using bolted packaging of the springs can damp a portion of the vibration and improve the performance. The drag force loss was found to account for 10-15% of the mechanical losses in a 100 Wnet LEA prototype. From the manufacturing perspective, use of water jet was found the most economical method for manufacturing the flexures which could make the commercial production of the LEAs feasible; however, for high-efficiency, high-durability machines, additional material treatments, and alternative manufacturing methods are essential

Nonintrusive parametric NVH study of a vehicle body structure

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Mechanics based design of structures and machines on 27/06/22, available online at: http://www.tandfonline.com/10.1080/15397734.2022.2098140A reduced order model technique is presented to perform the parametric Noise, Vibration and Harshness (NVH) study of a vehicle body-in-white (BIW) structure characterized by material and shape design variables. The ultimate goal is to develop a methodology which allows to efficiently explore the variation in the design space of the BIW static and dynamic global stiffnesses, such that the NVH performance can be evaluated already in the preliminary phase of the development process. The proposed technique is based on the proper generalized decomposition (PGD) method. The obtained PGD solution presents an explicit dependency on the introduced design variables, which allows to obtain solutions in 0.1 milliseconds and therefore opens the door to fast optimization studies and real-time visualizations of the results in a pre-defined range of parameters. The method is nonintrusive, such that an interaction with commercial software is possible. A parametrized finite element (FE) model of the BIW is built by means of the ANSA CAE preprocessor software, which allows to account for material and geometric parameters. A comparison between the parametric NVH solutions and the full-order FE simulations is performed using the MSC-Nastran software, to validate the accuracy of the proposed method. In addition, an optimization study is presented to find the optimal materials and shape properties with respect to the NVH performance. Finally, in order to support the designers in the decision-making process, a graphical interface app is developed which allows to visualize in real-time how changes in the design variables affect pre-defined quantities of interest.This project is part of the Marie Skłodowska-Curie ITN-EJD ProTechTion funded by the European Union Horizon 2020 research and innovation program with Grant Number 764636. The work of Fabiola Cavaliere, Sergio Zlotnik and Pedro D ıez is partially supported by the MCIN/AEI/10.13039/501100011033, Spain (Grant Number: PID2020-113463RB-C32, PID2020-113463RB-C33 and CEX2018-000797-S). Ruben Sevilla also acknowledges the support of the Engineering and Physical Sciences Research Council (Grant Number: EP/T009071/1).Peer ReviewedPostprint (published version

Design of a Novel Rear Cradle for Electrified Powertrains

With the ever-increasing, stringent requirements of fuel economy, automotive manufacturers have cited reduction of vehicle weight as one of the most effective methods of decreasing fuel consumption and emissions. Due to the abundance of traditional combustion-engine vehicles on the road, it is not uncommon for independent research groups or shops to convert these vehicles to hybrid, or full electric. In doing so, major changes to key structural aspects of the vehicle are required. However, it is far too often found that changes are made without proper analysis and design of the component. As such, this thesis provides an outline on the processes and methods used to develop a prototype structural component; in this case a custom rear cradle was used as an example, which was redesigned to house an electric motor drive unit in an existing production vehicle. Firstly, requirements such as structural strength, stiffness, and manufacturability were devised. In considering all these requirements, 6061-T6 aluminum was set as the new material for this component, given its high specific strength and stiffness, as well as ease of manufacturability and cost. Fatigue analysis was conducted to develop new structural requirements for this component, given its differing material properties from the previous design being made from steel. Next, topology optimization was conducted to gain an idea of an optimized, lightweight structure that met requirements. Structural analysis utilizing beam theory allowed for rapid iteration of tube diameters and wall thicknesses, this was translated to analysis of full geometry once requirements were met. All in all, the final design yielded a lighter component, while maintaining structural integrity. The new cradle design represents a weight savings of 57% over the 2019 cradle, while satisfying all the requirements set. It is expected that further weight reduction is possible, given future development in fatigue analysis and certain design aspects of the cradle. As such, the processes and methods outlined in this thesis can be applied to other structural components of similar nature for prototype vehicles.