Numerical Analysis of a New Concept Variable Valve Actuation System

<div class="htmlview paragraph">In February of 1987, Dresser introduced a pair of new mechanical drive, off-highway trucks designed to operate in the 35 to 60 ton, rear-dump, classes. These trucks, designated 140M and 210M, replaced three previous models while covering the same payload range. One distinctive feature of these new vehicles was their hydraulic system and in particular the brake control portion of this system.</div> <div class="htmlview paragraph">This new hydraulic brake control system can be described as a closed-center arrangement using a pressure-compensated, variable displacement pump as an energy source with accumulator-based energy reserves for independent and redundant circuits. In the basic version, a pair of pressure regulating valves are used to control system pressure at the brakes. These valves can be actuated in</div> <div class="htmlview paragraph"> <figure id="F1" class="figure"> <div class="graphic-wrapper"><img class="article-figure figure" src="911834_fig0001.jpg" alt="No Caption Available"/></div> </figure> </div> <div class="htmlview paragraph">tandem by a treadle (foot pedal) or separately by hydraulic pilot pressure. A single, filtered hydraulic fluid is used throughout the system and is stored in a single reservoir vented to atmosphere.</div> <div class="htmlview paragraph">The basic system is capable of accommodating multiple-axle (i.e. more than two) arrangements but was originally applied to a two-axle vehicle using dry, disc-type (caliper and rotor) brakes on all wheels. In February of 1990, the Model 140M and 210M trucks were revised to offer rear axle oil-cooled brakes as an option. The brake control system was subsequently modified to provide for this change primarily by the use of an additional pressure regulating valve and redundant circuitry.</div> <div class="htmlview paragraph">Both the original and latest versions of this system are characterized by their use of a unique emergency brake control system. Through the use of logic-type control valves, a loss of hydraulic pressure in one circuit is used to force the remaining high pressure circuits into actuating the brakes. This paper will describe the arrangement and operation of this hydraulic brake control system and its function as an integral part of the overall vehicle hydraulic system.</div>

In ultra-low temperature environment, the mechanical properties of bearing rotating in high speed change a lot, which has a great influence on the operation of machinery. To test the fatigue properties of air bearing, a hydraulic servo loading system for high-speed bearing in ultra-low temperature is designed and analyzed. According to the requirements of loading environment, this paper first designs a hydraulic servo loading system which could overcome the influence of high frequency disturbance. Then the components are selected with the related parameters in the hydraulic system calculated. Finally the simulation and analysis of the hydraulic system are carried out to verify the feasibility of the design by the AMESim software. All the research results above could provide reference for tests of aerospace high-speed bearing and designs of some other relevant hydraulic systems.

<div class="section abstract"> <div class="htmlview paragraph">This SAE Standard covers complete general and dimensional specifications for 37 degree flared and flareless types of hydraulic tube fittings and O-ring plugs. Also included are pipe fittings and adapter unions for use in conjunction with these tube fittings. These fittings are intended for general application in hydraulic systems on industrial equipment and commercial products.</div> <div class="htmlview paragraph">These fittings are capable of providing leak-proof, full-flow connections in hydraulic systems operating at working pressures as specified in SAE J1065, “Pressure Ratings for Hydraulic Tubing and Fittings.”</div> <div class="htmlview paragraph">Since many factors influence the pressure at which a hydraulic system will or will not perform satisfactorily, the values shown in SAE J1065 should not be construed as a guaranteed minimum.</div> <div class="htmlview paragraph">For any application, it is recommended that sufficient testing be conducted and reviewed by both the user and fitting manufacturer to assure that performance levels will be safe and satisfactory.</div> <div class="htmlview paragraph">The standard is divided into six sections as follows:</div> </div>

<div class="htmlview paragraph">One of the methods of representing a turbocharger-turbine in the exhaust system of internal combustion engines is by assuming quasi-steady flow at turbine boundaries, while taking into account the generation of pressure waves both upstream and downstream of the turbine due to non-steady flow conditions.</div> <div class="htmlview paragraph">This method relies substantially on steady flow turbine characteristics for the generation of boundary conditions. A method is presented to allow for wave action both upstream and downstream of a twin-entry radial inflow turbine. The method also allows for different flow rates in each entry to simulate the partial admission condition. Comparison is made between experimental results and theoretical analysis.</div>

<div class="section abstract"><div class="htmlview paragraph">The “Water Spider Geometry” (WSG) configuration, representing a newly developed reference test sample designed to suitably investigate the flow and heat transfer processes relevant to cooling systems of internal combustion engines, was computationally investigated by applying a recently proposed Reynolds Stress model called the “Elliptic-Blending Model” (EBM). The WSG configuration resembles a specifically configured pipe geometry that appropriately mimics the flow phenomena encountered in cooling channels of realistic internal combustion engine, such as flow impingement and bifurcation, multiple deflections and flow confluence. The reference database, consisting of mean flow and turbulence fields, was provided by a Large-Eddy Simulation. The EBM formulation has been intensively validated by calculating numerous isothermal wall-bounded flows. The present work focuses on testing the EBM predictive performances under the conditions of non-isothermal flow scenarios. Before proceeding to the WSG configuration, the EBM is pre-validated by computing a jet discharging from a channel-like nozzle and impinging perpendicularly onto a heated wall. The results obtained follow closely the data of the reference Direct Numerical Simulation, also with respect to the predicted second peak at the Nusselt number distribution in terms of different nozzle-to-wall spacing. The EBM-predicted mean velocity field and associated global flow characteristics within the WSG configuration agree well with the results of the reference Large-Eddy Simulation, in contrast to those obtained by the widely used <i>k</i> − <i>ω</i>-SST model, which has been applied in addition. Different treatments of the near-wall region were also used, including integration to the wall and the universal wall-functions. The computationally obtained temperature field evaluated at the WSG walls reveals the hot spot location within a straight pipe segment situated between two deflections, closer to the upstream one, coinciding with the experimentally detected region of most severe degradation caused by intense heating.</div></div>

<div class="htmlview paragraph">Engine manufacturers and product designers are currently under significant pressure to reduce fuel consumption, emissions, and noise from two-stroke engines. Improved engine breathing goes a long way toward overcoming these challenges by providing better charge delivery, complete exhaust gas scavenging, and minimal fuel short-circuiting.</div> <div class="htmlview paragraph">Reed valve motion and the resulting gas flow are highly coupled phenomena. Understanding and controlling these dynamics and their interactions is critical to effective intake breathing. A comprehensive effort to model reed valves at a level sufficient for engine design using engine simulations is still incomplete. This work is focused on the assessment, development and validation of a reed valve model suitable for engine simulations.</div> <div class="htmlview paragraph">In this work, a representative two-stroke engine reed valve is modeled in a detailed fluid/structures, multi-physics CFD code which fully resolves both the flow-field and the details of the deflecting reed plate.</div> <div class="htmlview paragraph">This same reed valve geometry is modeled in a 1D engine simulations code. In lieu of detailed experimental measurements, the CFD simulation results are used to provide the flow and lift data for various differential pressures. These are input into the 1D model as flow coefficients vs. lift.</div> <div class="htmlview paragraph">A comparison of results, between the 1D engine simulation and the original fluid/structure CFD, shows excellent agreement for the maximum lift, the lift vs. time profile, and for the overall flow predictions.</div> <div class="htmlview paragraph">In the 1D simulation code, the standard component model representation of a reed valve is as a spring-mass-damper physical model. It was found that this model, while not an exact representation of the bending reed, did provide adequate agreement.</div> <div class="htmlview paragraph">Additionally, the predicted lifts were compared with uniformly loaded deflecting beam theory assuming the up-stream and down-steam pressures are uniformly applied on either side of the reed valve. It was found that the while this assumption is an adequate first level approximation for low lift conditions and suitable for preliminary design analysis, the CFD results indicate that it does not hold for high lift conditions.</div> <div class="htmlview paragraph">In this work, a method was demonstrated which allows design engineers to investigate reed valve design options from the detailed CFD perspective and from the 1D engine simulations perspective, and thus to develop a good reed valve model for analysis prior to testing. This allows the engineer to screen potential designs with simulation before the more expensive task of building and testing prototypes. The validated reed valve model can be incorporated directly into a full engine simulation with confidence.</div>

<div class="section abstract"><div class="htmlview paragraph">In order to illustrate the constant development of the automatic transmission controls area, this paper describes how the garage shift calibration works in vehicles with transverse front wheel drive powertrains.</div><div class="htmlview paragraph">A garage shift (GS) is the turbine speed transient commanded by the shift lever movement from Park to Drive or Reverse, from Neutral to Drive or Reverse, from Drive to Reverse, from Reverse to Drive, or from Drive or Reverse to Neutral [<span class="xref">1</span>].</div><div class="htmlview paragraph">A usual metric to verify the garage shift comfort is the data acquisition of the fore-aft acceleration on the seat track, but also the shift time should be considered, as well as the clutch energy and the repeatability of the shift feeling for different temperatures and engine idle speed levels.</div><div class="htmlview paragraph">This paper demonstrates the transmission calibration strategies to determine a sensitive and a non-sensitive garage shift and its interactions with the engine calibration.</div><div class="htmlview paragraph">Many factors may affect the garage shift calibration, like hardware controls (software and calibration), hydraulic system (fluid and actuators), clutches (design and friction material) step ratios, and non-transmission factors such as idle control and engine torque signal accuracy [<span class="xref">2</span>]. The vehicle’s sensitivity to torsional driveline inputs and the powertrain mounts configuration also influence the shift quality perception.</div></div>

<div class="htmlview paragraph">Presenting a brand new approach to heat exchangers for engines, transmissions, hydraulic systems, etc.</div> <div class="htmlview paragraph">This new heat exchanger is made of only two pieces of circular extruded aluminum profiles: Core and shell. No soldering: The core and the shell is assembled by a minimum of automated work.</div> <div class="htmlview paragraph">In an oil to water cooling application, the active surface on the oil side of the core is enlarged by fins 0.2 mm thick, 0.3 mm spacing, and 3 mm high. The fins are made in unique production machines and enlarge the active surface area approximately five times compared to a conventional heat exchanger of the same dimensions.</div> <div class="htmlview paragraph">The principle utilizes the low pressure drop at laminar flow and avoids the disadvantage of low heat transfer after a certain laminar flow length. The result is approximately three times higher oil heat dissipation, combined with very low oil pressure drop, compared to conventional technique.</div> <div class="htmlview paragraph">The inner surface of the core, the water side, is extremely tolerant to dirty water and gives negligible pressure drop.</div> <div class="htmlview paragraph">This new heat exchanger is made of only one metal, aluminum. The characteristics of corrosion are therefore easy to define.</div>

<div class="section abstract"><div class="htmlview paragraph">Future legislation scenarios as well as stringent CO<sub>2</sub> targets, in particular under real driving conditions, will require the introduction of new and additional powertrain technologies. Beside the increasing electrification of the powertrain, it will be essential to utilize the full potential of the Internal Combustion Engine (ICE). There is clearly a competition of new and different ICE-Technologies [<span class="xref">1</span>] including VCR. VCR systems are expected to be introduced to a considerable number of next generation turbocharged Spark Ignited (SI) engines in certain vehicle classes. The implementation of Miller or Atkinson cycles is an essential criterion for increased geometric Compression Ratio (CR). The DUAL MODE Variable Compression System (VCS)<sup>TM</sup> enables a 2-stage variation of the connecting rod length and thus of the compression ratio (CR). The concept allows a modular integration into existing engine families without significant modifications of the engine architecture and thus represents a cost-attractive solution. The basic functionality and potential were described in a technical paper which was presented at the SAE WCX 2017 [<span class="xref">2</span>], the development of the hydraulic function and oil investigations were presented at the SAE WCX 2018 [<span class="xref">3</span>].</div><div class="htmlview paragraph">This paper describes the engine integration of the Dual Mode VCS-system including the hydraulic control system into a state-of-the-art 2.0L-Turbo Gasoline Direct Injected (TGDI)-Engine for the vehicle boundaries of a midsize Sports Utility Vehicle (SUV).</div><div class="htmlview paragraph">Switching strategies, as well as the importance of short switching duration under Worldwide Harmonized Light Vehicle Test Procedure (WLTP) as well as Real Driving Emissions (RDE) requirements are discussed.</div><div class="htmlview paragraph">The applied fail-safe operation and Dual Mode VCS position control and detection will be described.</div><div class="htmlview paragraph">Finally, the Fuel Consumption (FC) impact of the Dual Mode VCS system is discussed. For the 2.0L-TGDI engine in the actual vehicle class, dependent on the load profile and the specific power and torque requirements a CO<sub>2</sub> reduction between 5% and up to 9% in the WLTP is achievable.</div></div>

<div class="htmlview paragraph">In this paper we describe the main steps of the Vehicle Dynamics design using the generalized procedures of System Dynamics Modeling, Simulation and Analysis.</div> <div class="htmlview paragraph">The methodology discussed is illustrated by a vehicle adaptation design, where the best kind of damper, for the passengers comfort, must be selected.</div> <div class="htmlview paragraph">The Bond Graphs technique is used for the mathematical model development of a seven degrees of freedom vehicle, and three dampers constitutive relations are defined.</div> <div class="htmlview paragraph">Digital simulation is employed for the vehicle behavior valuation, and we compare the roll angle for the three dampers.</div> <div class="htmlview paragraph">Finally the analysis techniques for the optimization of the damper's selection are discussed.</div> <div class="htmlview paragraph">The paper is concluded claiming the importance of this approach in engineering design involving high technology and complexity.</div>

<div class="section abstract"> <div class="htmlview paragraph">This SAE Standard provides general, dimensional, and performance specifications for the most common hoses used in hydraulic systems on mobile and stationary equipment.</div> <div class="htmlview paragraph">The general specifications contained in <span class="xref">Sections 1</span> through <span class="xref">12</span> are applicable to all hydraulic hoses and supplement the detailed specifications for the 100R-series hoses contained in the later sections of this document. (See <span class="xref">Table 1</span>.)</div> <div class="htmlview paragraph">This document shall be utilized as a procurement document only to the extent as agreed upon by the manufacturer and user.</div> <div class="htmlview paragraph">The rated working pressure of a hose assembly comprising SAE J517 hose and hose fitting end connections per SAE J516, J518, J1453, etc., shall not exceed the lower of the respective SAE working pressure rated values.</div></div>

<div class="section abstract"> <div class="htmlview paragraph">This SAE Standard provides general, dimensional, and performance specifications for the most common hoses used in hydraulic systems on mobile and stationary equipment.</div> <div class="htmlview paragraph">The general specifications contained in <span class="xref">Sections 1</span> through <span class="xref">12</span> are applicable to all hydraulic hoses and supplement the detailed specifications for the 100R-series hoses contained in the later sections of this document. (See <span class="xref">Table 1</span>.)</div> <div class="htmlview paragraph">This document shall be utilized as a procurement document only to the extent as agreed upon by the manufacturer and user.</div> <div class="htmlview paragraph">The rated working pressure of a hose assembly comprising SAE J517 hose and hose fitting end connections per SAE J516, J518, J1453, etc., shall not exceed the lower of the respective SAE working pressure rated values.</div></div>

<div class="htmlview paragraph">This paper deals with the design and manufacturing of a mechanical variable valve actuation system, developed as part of the MUR financed research project concerning the realization of a high performance motorcycle engine, through a partnership of Moto Morini S.P.A. (BO), Dell’Orto S.P.A. (MI), Istituto Motori - CNR (NA), and DIME - Università di Napoli Federico II.</div> <div class="htmlview paragraph">After a synthetic description of the main variable valve actuation methods currently employed (timing, duration and lift variation, cyclic cylinder deactivation), the paper presents the results of our mechanical variable valve actuation system, consisting of three main elements: cam, main rocker arm with fixed fulcrum and secondary rocker arm with mobile fulcrum. It enables valve lift variation through a simple translation of the intermediate element (system 1).</div> <div class="htmlview paragraph">The study has been conducted implementing a numerical procedure specifically designed to determine cam profile and the kinematic and dynamic characteristics of the whole system, starting from the following input data: rocker arm geometry, relative positions and inertial data of elements, spring stiffness and preloading, camshaft speed and valve lift law. The model has been validated against the conventional timing system using kinematic simulations.</div> <div class="htmlview paragraph">Results of the numerical procedure verify the validity of the variable valve actuation system, capable of a valve lift variation from 30% to 100% of the maximum lift, with a limited acceleration (lower than maximum values). Based on the numerical results, we are developing a new mechanical variable valve actuation system. The new system consists of the same three elements used previously, but they are connected in a different way (system 2). The newer system enables more general lift profile distributions with a similar geometric complexity.</div> <div class="htmlview paragraph">A maximum closing limited to 30% does not enable cyclic deactivation of some cylinders (strategy feasible on multicylinder engines) or exclusion of one or more valves (strategy feasible on multivalve engines).</div> <div class="htmlview paragraph">The activity was extended to research for a new solution (always a mechanical system), capable to allow inlet valves complete closing and timing and duration variation (system 3).</div> <div class="htmlview paragraph">This paper reports results reachable with the simplest system 1. This new system gives better perspectives of use for a new two-wheel vehicle engine.</div>

<div class="section abstract"> <div class="htmlview paragraph">The SAE J3211 procedure applies to squeal evaluation for foundation brakes using single-ended inertia dynamometers for friction couples used on vehicles with regenerative braking systems. This document applies to squeal noise occurrences for on-road passenger cars and light trucks with a gross vehicle weight rating of 4536 kg or below and with at least one rechargeable energy storage system as a source for propulsion. The procedure incorporates aspects related to (a) minimum inertia dynamometer capabilities, (b) fixture requirements and setup, and (c) test sequences with emphasis on brake temperatures, brake pressure profiles, and strategies to represent brake blending.</div> <div class="htmlview paragraph">For this document, squeal occurs when the peak noise level is at least 70 dB(A) between 1.25 and 16 kHz for tests using full suspension corners or complete axle assemblies, or between 2 and 16 kHz for brakes not using an entire suspension corner.</div> <div class="htmlview paragraph">Test facilities intending to use this document, building on their expertise in conducting SAE J2521, shall review in detail the changes to test parameters (mainly brake temperatures and brake pressures) for legacy modules.</div> <div class="htmlview paragraph">This document also applies to vehicles with electromechanical braking systems to actuate the foundation brake. The test requester and the test facility are responsible for converting the hydraulic pressure levels into their equivalent clamping forces for brakes using electromechanical actuation.</div> <div class="htmlview paragraph">Before using this document for chassis dynamometer testing, review in detail the specifics related to at least (a) instrumentation, including in-cabin microphones; (b) threshold levels for noise detection; (c) temperature control priority between the front and rear axles; (d) vehicle loading and load distribution; (e) cooling air and environmental conditioning; (f) detailed terminology and labeling of channels and sensors; and (g) the regenerative settings and the state of charge during the test.</div> <div class="htmlview paragraph">Before using this document along with other methods to recreate the regenerative brake blending (e.g., Software-in-the-Loop or Hardware-in-the-Loop), consider (a) the vehicle powertrain, blending architecture and its applicable models, (b) actual profiles intended to recreate (e.g., control strategies, state of charge, test scenarios), and (c) actual embodiment of the simulation and integration with the native controls of the brake dynamometer.</div> <div class="htmlview paragraph">This document does not include noise from other sources (e.g., parking brakes, electric machines, driveline components).</div> </div>

<div class="section abstract"><div class="htmlview paragraph">With the increasingly strict emission regulations and economic demands, variable valve trains are gaining in importance in Diesel engines. A valve control strategy has a great impact on the in-cylinder charge motions, turbulence level, thus also on the combustion and emission formation. In order to predict in-cylinder charge motions and turbulence properties for a working process calculation, a zero−/quasi-dimensional flow model is developed for the Diesel engines with a fully variable valve train. For the purpose of better understanding the in-cylinder flow phenomena, detailed 3D CFD simulations of intake and compression strokes are performed at different operating conditions with various piston configurations.</div><div class="htmlview paragraph">In the course of model development, global in-cylinder charge motions are assigned to idealized flow fields. Among them, swirl flow is characterized by an engine swirl number that is determined by both developments of the swirl angular momentum and the moment of inertia. The generation of swirl angular momentum during intake is estimated from the intake mass flow and instantaneous stationary swirl number. The latter is obtained from virtual flow bench simulations in consideration of valve phasing. When modeling swirl losses during compression and expansion, the effects of wall friction, turbulent conversion as well as piston motion are taken into account. Furthermore, a sub-model describing the flows induced by piston motion including axial and squish flows is set up. In conjunction with the charge motion model, a quasi-dimensional turbulence model is developed based on the k-ε turbulence model. Turbulence production rate and dissipation are determined through sub-models. Inflow turbulence is modeled as local shear in the cylinder entrance area. TKE out of axial flows is transferred latish from the axial kinetic energy. Besides, turbulence productions from squish and swirl flows are approximated using idealized flow fields. Dissipation is estimated in a zero-dimensional sub-model by means of a newly developed turbulence length scale, which takes account of all the influences of in-cylinder flow, inflow and back squish flow.</div><div class="htmlview paragraph">The results from the performed validations demonstrate that the proposed flow model accurately predicts the temporal change of in-cylinder flow quantities and also responds correctly to the variations of piston configuration as well as operating conditions such as engine speed, charging pressure and valve actuation. Further application of the model in other Diesel engines is feasible by tuning certain model parameters.</div></div>