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A Numerical Investigation on VVA Influence on the Combustion Phase for Premixed Combustion Engine Under Partial Load Conditions

DMMM - Politecnico di Bari-Sergio Camporeale
DMMM - Politecnico di Bari, GNFM INDAM-Francesco Fornarelli
  • Technical Paper
  • 2020-37-0005
To be published on 2020-06-23 by SAE International in United States
Nowadays, the vehicle hybridization and the use of more clean fuel in heavy-duty applications brings to a new beginning in the use of spark ignition engine. In standard intake system, the pre-mixed fuel air mixture is controlled by the injection of fuel after the throttle valve. Then, intake system, consisting in intake duct, valve number and geometry and cylinder head shape influence the characteristics of the intake flow within the cylinder up to the ignition of the combustion by the spark plug. The technology advancement in fluid-power and electrical actuation gives the opportunity to decouple the intake and exhaust valve actuation with respect to the standard cam shaft distribution. The Variable Valve Actuation (VVA) concepts is not new, but its application is now affordable and flexible enough to be applied in partial load conditions. Here, by means of three-dimensional numerical simulations the intake and combustion process is studied with a finite volume approach to solve the mass, momentum and energy equations together with an Extended Coherent Flamelet Model (ECFM). Two different approaches in driving the…
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A Holistic Approach to Develop a Modern High-Power Density Diesel Engine to Meet Best-in-Class NVH Levels

Mahindra & Mahindra, Ltd.-Vikraman Vellandi, Prasad Namani, Rajkumar Bhagate, Madhu Chalumuru
  • Technical Paper
  • 2020-01-0406
To be published on 2020-04-14 by SAE International in United States
The ever-increasing customer expectations put a lot of pressure on car manufacturers to constantly reduce the noise, vibration, and harshness (NVH) levels. This paper presents the holistic approach used to achieve best-in-class NVH levels in a modern high-power density 1.5 lit 4-cylinder diesel engine. In order to define the NVH targets for the engine, global benchmark engines were analysed with similar cubic capacity, power density, number of cylinders and charging system. Moreover, a benchmark diesel engine (considered as best-in-class in NVH) was measured in a semi-anechoic chamber to define the engine-level NVH targets of the new engine. The architecture selection and design of all the critical components were done giving due consideration to NVH behaviour while keeping a check on the weight and cost. Extensive 1D crank-train simulations were carried out to ensure that the crankshaft torsional amplitude was contained less than the NVH limit of 0.1 degree for higher-order excitations. Similarly, the flywheel-end speed irregularity was confirmed to be within acceptable limits. A complete engine-level simulation was carried out to simulate the surface velocities…
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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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EDITORIAL: There is no substitute for ‘Automotive Grade’

Automotive Engineering: September 2019

Editor-in-Chief-Lindsay Brooke
  • Magazine Article
  • 19AUTP09_05
Published 2019-09-01 by SAE International in United States

When you get in a vehicle and push the ‘start’ button, you're betting that the machine will get you to your destination safely and reliably, regardless of the driving conditions. Lives are at stake the moment you lift off the brake pedal.

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Variable Cam Timing (VCT) Knock Root Cause Analysis and Failure Mode Prevention

Ford Motor Company-Mohammad Moetakef, Debabrata Paul, Georg Festag
Published 2019-01-18 by SAE International in United States
Knock in the Camshaft Torque Actuated (CTA) in the Variable Cam Timing (VCT) engine can be a NVH issue and a source of customer complaint. The knock noise usually occurs during hot idle when the VCT phaser is in the locked position and the locking pin is engaged. During a V8 engine development at Ford, the VCT knock noise was observed during hot idle run. In this paper investigation leading to the identification of the root cause through both test and the CAE simulation is presented. The key knock contributors involving torque and its rate of change in addition to the backlash level are discussed. A CAE metric to assess knock occurrence potential for this NVH failure mode is presented. Finally a new design feature in terms of locking pinhole positioning to mitigate or eliminate the knock is discussed.
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Electric Camshaft Phasing System to Meet Euro 6/BS-VI Emission Norms for Gasoline Engine

SAE International Journal of Advances and Current Practices in Mobility

Schaeffler Group, USA Inc.-Andrew Mlinaric
Schaeffler India, Ltd.-Shabbir Sheikh, Uday Deshmukh, Krishna Kumar Rathore
  • Journal Article
  • 2019-26-0055
Published 2019-01-09 by SAE International in United States
In today’s ever-changing scenario, gasoline engine is going to be more acceptable passenger vehicle prime mover, as it meets Bharat Stage-VI (BS-VI) emission standard and need less cost of up-gradation. Variable cam phasing (VCP) system is well known & proven advanced technology in automotive world, which already used by many OEMs globally to improve fuel consumption and reduce engine emissions. Electric Cam Phasing (ECP) is an integration of electro-mechanical system. In ECP, angle shifting is independent of engine oil pressure, which allows a more aggressive engine calibration of valve timing to minimize active intervention in the ignition and fuel injection sequences. Early advance timing makes it possible for the combustion engine to build up torque more quickly during acceleration, which means that ECP not only helps to achieve high operating efficiency, but also good driving performance. This paper will describe use of advanced features of ECP over Hydraulic Cam Phaser (HCP) in achieving improved fuel consumption & reduction in HC & CO emissions to meet BS-VI standard by precise controlling of valve timing at engine…
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Analysis of Rotational Vibration Mechanism of Camshaft at High Engine Speed in Engines with In-Line Four-Cylinder DOHC Configuration

Honda R&D Co., Ltd.-Ryoh Hatakeyama, Tadashi Niino
Published 2018-10-30 by SAE International in United States
In engines having an inline four cylinder DOHC configuration, the rotational vibrations of camshaft increase at high engine speeds above 10000 rpm, causing an increase of tension in the cam chain. It is therefore difficult to realize an optimum designing of a cam chain system when the durability has to be taken into considerations. Using the simulation we analyzed in this research how the rotational vibrations and tension increase at high engine speeds in an inline four cylinder DOHC engine. As its consequent, it is understood that the increases of rotational vibrations and tension caused by the resonance of the spring mass vibration system in which the cam chain serves as springs and the camshafts as the equivalent masses. Also it is found out that the vibration system is of a unique non-linear type in which the resonance of the fourth order frequency is also excited by the crankshaft torque fluctuations of the second order frequency. Furthermore, it is uncovered that the natural frequency of the vibration system shifts from a value to another with…
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Design and Development of a Roller Follower Hydraulic Lash Adjustor to Eliminate Lash Adjustment and Reduce Noise in a Serial Production Diesel Engine

Eaton-Leighton Roberts, James McCarthy, Jr.
Published 2018-09-10 by SAE International in United States
Commercial vehicles require continual improvements in order to meet fuel emission standards, improve diesel aftertreatment system performance and optimize vehicle fuel economy. Aftertreatment systems require significant space claim which makes vehicle packaging a challenge. Today’s diesel engines require valvetrain lash adjustment settings at distinct intervals to ensure proper valvetrain performance. This requires removing the engine rocker cover to access the valvetrain rocker arms for setting lash. Setting lash for compact vehicle applications sometimes requires removing the aftertreatment system to provide access to the rocker cover prior to setting lash. Then, the rocker cover is reinstalled followed by the aftertreatment system making the lash setting process time consuming and complex. This paper focuses on the design, development and validation of adapting hydraulic lash adjusters (HLAs) into a type V (camshaft in block) diesel engine thus eliminating the lash adjustment process. The flat mechanical tappets were replaced with roller follower HLAs on both the intake and exhaust valves. The roller was included to reduce valvetrain friction over flat tappets. An anti-rotation design was included to maintain alignment…
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Joint Mechanism and Prediction of Strength for a Radial Knurling Connection of Assembled Camshaft Using a Subsequent Modeling Approach

SAE International Journal of Engines

Jilin University-Shuqing Kou, Chao Li
Taiyuan University of Technology-Peng Zhang, Zimin Kou
  • Journal Article
  • 03-11-03-0020
Published 2018-06-25 by SAE International in United States
Knurling joint applied in assembled camshaft has developed rapidly in recent years, which have exhibited great advantages against conventional joint methods in the aspects of automation, joint precision, thermal damage, noise, and near net shape forming. Both quality of assembly process and joint strength are the key requirements for manufacturing a reliable assembled camshaft. In this article, a finite element predictive approach including three subsequent models (knurling, press-fit and torsion strength) has been established. Johnson-Cook material model has been used to simulate the severe plastic deformation of the material. The residual stress field calculated from the knurling process was transferred as initial condition to the press-fit model to predict the press-fit load. The predicted press-fit load, torque strength and displacement of cam profile before failure were calculated. The torque strength of the joint was twice higher than that of a typical passenger vehicle requirement. The torque strength was significantly positive correlated to the press-fit load. Taking the knurling tool dimensions and feed amount as variables, the relationships between them and press-fit as well as joint…
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