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A Method for Improvement in Data Quality of Heat Release Metrics Utilising Dynamic Calculation of Cylinder Compression Ratio

SAE International Journal of Engines

Kistler AG, Switzerland-Mario Nahkle, David R. Rogers, Janko Meier
University of Stuttgart, Germany-Hubert Fusshoeller, Michael Bargende
  • Journal Article
  • 03-13-02-0010
To be published on 2020-04-30 by SAE International in United States
One of the key factors for accurate mass burn fraction and energy conversion point calculations is the accuracy of the compression ratio. The method presented in this article suggests a workflow that can be applied to determine or correct the compression ratio estimated geometrically or measured using liquid displacement. It is derived using the observation that, in a motored engine, the heat losses are symmetrical about a certain crank angle, which allows for the derivation of an expression for the clearance volume [1]. In this article, a workflow is implemented in real time, in a current production engine indicating system. The goal is to improve measurement data quality and stability for the energy conversion points calculated during measurement procedures. Experimental and simulation data is presented to highlight the benefits and improvement that can be achieved, especially at the start of combustion. The method calculated a compression ratio correction of 0.3 and 0.25 on two different gasoline engines, respectively. At 2000 rpm a deviation in the 5% and 10% energy conversion angles (CA05 and CA10) of…
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Optimization of Compression Ratio for DI Diesel Engines for better fuel Economy

Tata Technologies, Ltd.-Sujit Gavade, Aashish Bhargava, Gaurav Soni, Chandrakant Deshmukh
  • Technical Paper
  • 2019-28-2431
To be published on 2019-11-21 by SAE International in United States
Fuel economy is becoming one of the key parameter as it not only accounts for the profitability of commercial vehicle owner but also has impact on environment. Fuel economy gets affected from several parameters of engine such as Peak firing pressure, reduction in parasitic losses, improved volumetric efficiency, improved thermal efficiency etc. Compression ratio is one of key design criteria which affects most of the above mentioned parameters, which not only improve fuel efficiency but also results in improvement of emission levels. This paper evaluates the optimization of Compression ratio and study its effect on Engine performance. The parameters investigated in this paper include; combustion bowl volume in Piston and Cylinder head gasket thickness as these are major contributing factors affecting clearance volume and in turn the compression ratio of engine. Based on the calculation results, an optimum Compression Ratio for the engine is selected. Further Engine testing carried out with selected Compression ratios and parameters such as Fuel efficiency, In cylinder pressure, Brake thermal efficiency and Ignition delay were compared.
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Development of a Measuring System for the Visualization of the Oil Film between the Piston and Cylinder Liner of a Gasoline Engine

SAE International Journal of Engines

Technical University of Munich, Germany-Julian Schäffer, Claus Kirner, Martin Härtl, Georg Wachtmeister
  • Journal Article
  • 03-13-02-0013
Published 2019-11-14 by SAE International in United States
The design of cylinder liners, pistons, and piston rings is subject to different conflicting goals. In addition to a loss-free seal of the combustion chamber, sufficient oil must be present between the friction partners. Both the reduction of piston assembly friction and the minimization of oil consumption are crucial to achieve the strictly defined CO2 and emission standards. To master this challenge and find the best compromise requires a lot of system-specific know-how. The automobile and engine manufacturers focus mainly on friction-reducing measures, which are analyzed with different measuring methods such as the floating-liner method, the strip-down method, or the instantaneous indicated mean effective pressure (IMEP) method. However, the interpretation of the results and the development of realistic simulation models lacks information about the oil film behavior and the film thickness. In order to gain this missing knowledge, instruments for oil film visualization and oil film thickness measurement have to be developed. In this study, the two-dimensional laser-induced fluorescence method (2D-LIF) is used to visualize the lubricating oil film between the piston and the cylinder…
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Study on Engine Start Vibration Index in a Hybrid Powertrain Using Torque Sensor and Cylinder Pressure Sensor

Tsinghua University-Fuyuan Yang, Lei Du, Yaodong Hu
Published 2019-11-04 by SAE International in United States
This paper presents an investigation of drivability issue of engine start-stop. Hybrid vehicles provide excellent benefits regarding fuel efficiency and emission. However, vibration results from constant engine start and stop events generate drivability issues, thus compromising driving comfort. This paper has designed a high speed torque sensor to capture instantaneous torque at the engine shaft. Its consequences help to find out the most suitable index of vibration severity. This paper is organized in four sections. The first section introduces the powertrain to be studied. The second section introduces development of a specially designed torque sensor. The torque sensor is installed between the engine and ISG (Integrated Starter Generator), alongside with an encoder. The torque sensor is utilized to collect the instantaneous shaft torque on occasion of engine start. In the third section, this paper has performed two experiments. Firstly, a typical engine start process (from 0 to 650 rpm) is studied. Instantaneous shaft torque, encoder signal and cylinder pressure signals are gathered and synchronized. Cranking phase and initial combustion phase is observed. It is concluded…
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A Comparative Study on ESC Drive and Brake Control Based on Hierarchical Structure for Four-Wheel Hub-Motor-Driven Vehicle

Wuhan University of Technology-Chen Lin, Xiaofei Pei, Xuexun Guo
Published 2019-11-04 by SAE International in United States
Electronic Stability Control (ESC) is an important measure to proactively guarantee vehicle safety. In this paper, the method of four-wheel hub-motor torque control is compared with the traditional single-wheel hydraulic brake control in ESC system. The control strategy adopts the hierarchical structure. In upper controller, the stability of the vehicle is identified by threshold method, the additional yaw moment control uses a way to get the moment including feedforward and feedback parts based on the linear quadratic regulator (LQR). The medium controller is tire slip rate control, in order to get the optimal target slip rate from the upper additional yaw moment, a method of quadratic programming to optimize the longitudinal force is proposed for each wheel. The inputs of tire state for the magic tire model is introduced so as to calculate the target slip rate from the target longitudinal force. The lower controller is wheel cylinder pressure control and motor torque control which is realized by Carsim ideal control. Finally, through Co-simulation of Carsim/Simulink in the condition of open steering wheel loop for…
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Optimal Speed Profile for Minimum Vibration during Engine Start Using Pontryagin’s Minimum Principle Approach

Tsinghua University-Lei Du, Liangfei Xu, Yaodong Hu, Minggao Ouyang, Fuyuan Yang
Published 2019-11-04 by SAE International in United States
An imperceptible engine start is critical to the acceptance of hybrid vehicles. This paper focusses on an optimal control problem that tries to reduce vibration during engine start. Efforts are made to obtain the optimal speed trajectory that could cause minimum vibration during engine start. In the first section, the target diesel powertrain is introduced. A four cylinder diesel engine is coaxially paralleled with an ISG motor. The ISG motor serves as the engine starter and engine flywheel. Its dynamic model is established using crank-link dynamics. Secondly, an index is brought out to evaluate the severity of vibration. The cylinder pressure variation is the main cause of engine torque ripple, which in turn results in engine speed fluctuation. The square of the angular acceleration is chosen as the index of vibration. The index shows a positive relation of cylinder pressure in terms of amplitude. Then, the author models this problem as a continuous-time optimal control problem with a fixed terminal time and a partially free terminal state, then solve it by the Pontryagin’s minimum principle.…
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More sting for the STINGRAY

Automotive Engineering: November/December 2019

Don Sherman
  • Magazine Article
  • 19AUTP11_02
Published 2019-11-01 by SAE International in United States

GM Propulsion engineers elevate the evergreen small-block V8 to new heights for its mid-engine Corvette mission.

Instead of heaving decades of small-block V8 expertise out the window, GM Propulsion engineers led by chief engineer Jordan Lee leveraged past success to create a new-for-2020 V8. Known as the LT2, the 6.2-L V8 gives Chevy's all-new, eighth-generation 2020 Corvette more power (the most yet in the base Stingray), stirring response, and competitive fuel efficiency compared with the outgoing C7.

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Is the camshaft being timed out?

Automotive Engineering: November/December 2019

Stuart Birch
  • Magazine Article
  • 19AUTP11_12
Published 2019-11-01 by SAE International in United States

The development of electric vehicle motors, power controls and batteries tend to dominate today's industry's headlines, but R&D of internal combustion engine technologies in its many forms continues. That is underlined by the U.K.'s Brunel University establishing a new future-powertrain research program centering on “intelligent” valve technology and the eventual replacement of the conventional camshaft by electric actuators.

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Engine Cylinder Head Thermal-Mechanical Fatigue Evaluation Technology and Platform Application

SAE International Journal of Engines

Jiangling Motor Company Limited, China-Xuwei Luo
Jiangling Motor Company, China-Xiaochun Zeng
  • Journal Article
  • 03-13-01-0008
Published 2019-10-14 by SAE International in United States
An in-cylinder combustion analysis and a computational fluid dynamics (CFD) coolant flow analysis were performed using AVL FIRE software, which provided the heat transfer boundary conditions (HTBCs) to the temperature field calculation of the cylinder head. Based on the measured material performance parameters such as stress-strain curve under different temperatures and E-N curve, creep, and oxidation data material performance, the cylinder head-gasket-cylinder block finite element analysis (FEA) was performed. According to the temperature field calculation results, the maximum temperature of the cylinder head is 200°C that is within the limit of ALU material. The temperature of the water is more than 21.1°C below the critical burnout point temperature. The high-cycle fatigue (HCF) and thermal-mechanical fatigue (TMF) analysis of the cylinder head were performed by FEMFAT software. The HCF safety coefficient and TMF life cycle of the cylinder head were calculated, which provided an important guidance for cylinder head structure design of a gasoline engine and diesel engine. The present article establishes a complete simulation and analysis process of cylinder head TMF. The fatigue assessment technology…
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Design of a Novel Electro-Pneumatic Gear Shift System for a Sequential Gearbox

Vellore Institute of Technology-Jeevesh Jain, Vaibhav Mittal, Dore Ranganath Srinivasa Raghuraman, Shivam Singh Rathore, Sumit Nilesh Vadodaria
Published 2019-10-11 by SAE International in United States
This paper describes the design of a novel pneumatic gear shifting system to replace the existing gear stick manual shifting system for ease of the driver while shifting gears. The aim of this work is to have a semi-automatic shifting (pneumatic shifting) removing the need for the driver clutch operation. The system consists of a solenoid valve, CO2 gas-pressurized cylinder, double-acting cylinder, and single-acting cylinder. On basis of the signal received the gear needs to be changed, the shifter opens or closes a magnetic valve assembly. The solenoid valve allows the compressed air into the piston that comes from a pressurized cylinder, in order to create the effect of shifting gears. The pedal shifter and buttons are used to shift the gears. The pedal shifter was designed by using a 3-D printing technique using PLA material. The microcontroller used is ATMEGA-328 in this system. There are three switches, one for upshift, downshift, and clutch respectively. An algorithm has been created in a microcontroller for a sequential gearbox of CBR 600RR. The system has been so…
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