Development of a Transient Thermal Analysis Model for Engine Mounts

<div class="htmlview paragraph">It was desired to optimize an existing design concept of an active engine mount technology intended for engines with controlled cylinder deactivation. Specifically, this case study addresses how this active Noise & Vibration countermeasure was optimized using techniques derived from Taguchi Robust Engineering and DFSS strategies.</div> <div class="htmlview paragraph">This paper will focus primarily on how the appropriate robust design strategy was applied including the selection of the response function, a properly sized orthogonal array for the design control factors, and a sufficient noise strategy.</div> <div class="htmlview paragraph">A discussion of the design control factors, noise factors, Design of Experiment (DOE), and post-experiment standardized signal-to-noise ratio optimization analysis of the non-linear response function will be presented.</div> <div class="htmlview paragraph">Design control parameters included passive attributes of hydraulic engine mounts, as well as active/electronic components. Noise strategy was defined using three variables; heat and load cycling aging, ambient temperature, and static preload.</div> <div class="htmlview paragraph">In addition, passive performance of the active mount was analyzed using non-dynamic response functions and checked against best practice performance requirements.</div> <div class="htmlview paragraph">Results obtained from the study have documented the process to optimize a design for variation using dynamic response function for the active behavior of the mount, and nominal-the-best Type I from Taguchi Methods for passive behavior. The optimized design is planned to be prototyped and verified by experiment.</div> <div class="htmlview paragraph">The paper documents the application of the latest thinking in the field of Robust Engineering and DFSS strategies. The methods, techniques, and process are equally applicable to other elastomer based anti-vibration devices.</div>

<div class="htmlview paragraph">Recent interest in applications of adaptive engine mounts to improve ride quality and passenger comfort has introduced new research areas in the field of vehicle dynamics and control. Introduction of vehicles with smaller engines and lighter and more flexible frames, for the purpose of improving fuel economy, has led to increased frame vibration levels. Frame vibration at engine idle speeds is caused by engine firing and imbalance forces which are transmitted primarily through the engine mounts. Consequently, effort has been focused on improving engine mount technology to achieve better vibration isolation.</div> <div class="htmlview paragraph">Introduction of adaptive engine mounts into the dynamics of a flexible engine-frame system requires an integrated study from both vibration and control points of view. This paper presents the results of an on-going research on applications of adaptive hydraulic mounts, manufactured by Cooper Industrial Products, on a Ford Ranger Light Truck. Several issues have been studied which form the fundamentals for optimal implementation of adaptive engine mounts. These include: system modeling, controller design, required sensors, and design of new actuators. The focus of this paper is on the controller design for hydraulic engine mounts. In particular, the issue of open-loop control versus closed-loop control will be discussed and performance of these control schemes once implemented on the actual vehicle will be compared.</div>

<div class="htmlview paragraph"><b>VIBRATION formerly was classed as such without much thought as to the determination of its sources, Mr. Taub states, and then came isolation of the various causes. The first two vibrations to be segregated and vigorously attacked were the secondary inertias of reciprocating units and torsional vibration. The development of the six-cylinder engine was among the earliest attempts to eliminate secondaries, and it was also the earliest producer of torsional vibration.</b></div> <div class="htmlview paragraph"><b>Dynamics, combustion roughness, torsional roughness and structural weakness, are a few of the contributing causes of engine roughness. Consideration must be given to all these factors if an engine is to be considered inherently smooth, and each is analyzed.</b></div> <div class="htmlview paragraph"><b>Engine mountings should have low resistance to rotation about the longitudinal principal axis and to rotation about the vertical axis through the center of gravity, together with minimum shift of affective principal axis and vertical axis. The kind of material used in engine mountings should be determined after considering the overall characteristics of the mounting and the durability of those characteristics.</b></div>

<div class="section abstract"><div class="htmlview paragraph">During the last decade, fuel economy mandates (CAFE regulations) have driven engine downsizing and down-speeding trends. More recently, downsized turbos are percolating down to heavier SUVs and trucks. Larger/heavier vehicles require high torque engines to provide attractive dynamic performance. While higher torque requirements can be satisfied with new innovations like the variable compression engine, larger and more upscale vehicles also need to deliver higher quietness requirements. For this, the vibration control system for combustion induced forces with high torque engines become very important. To address both dynamic performance and quietness requirements, active engine mounts have been previously adopted, however challenges for light-weighting, downsizing, and costs have still persisted.</div><div class="htmlview paragraph">A new vibration isolation technology using passive and active vibration isolation system named Active Torque Rod(ATR) was studied for application to a new vehicle to realize quietness targets with a smaller, lighter, and less expensive engine mount system. The basic concept of the active torque rod is to set it’s resonance below 200 Hz so as not to degrade the acceleration noise due to down-sizing by utilizing the passive vibration-isolation region. However, the engine primary order (2<sup>nd</sup> order) booming noise degrades due the torque rod resonance below 200 Hz. Therefore, the resonance amplitude is suppressed by utilizing an inertia mass actuator in the torque rod and inputting an out-of-phase control force corresponding to the engine 2nd order input.</div><div class="htmlview paragraph">Technical details of ATR has been previously presented by R. Yamauchi, et al. [<span class="xref">4</span>]. Therefore this paper focuses on the benefits of applying an ATR to a premium C-segment SUV under development with a new inline 4-cylinder turbocharged engine. In order to achieve the acceleration noise targets, an active upper torque rod was applied to counter the large roll reaction force input. Acceleration noise levels were reduced by about 4 dB in the 250-800 Hz range when compared to conventional (passive) torque rod system. Both acceleration noise and booming noise achieved class leading levels. The proposed mounting system is approximately 8 kg lighter than the existing active control engine mount system.</div></div>

<div class="htmlview paragraph">In recent years, high performance engines and the reduction in engine room due to aerodynamic styling has caused increases in engine room temperature. Because of this increasing temperature, the conventional natural rubber engine mount is now at the marginal point on its performance and durability. Several heat resistant materials have been considered for engine mount applications because of this reason. Polychloroprene rubber could be a strong candidate for engine mount application due to its balance of heat resistance, dynamic properties, and fatigue life. This paper will discuss the development of the technology, property characteristics and part performance simulations on the HYUNDAI BUSH TYPE COMPLEX ENGINE MOUNT (for 2.0L DOHC ENGINE). This type of mount requires higher creep resistance and fatigue life than those of other designs, such as block or simple shear type mounts. Early evaluations of polychloroprene mounts have shown some deficiencies in creep resistance. Therefore to adress this concern, the design and formulation development to overcome the initial lack of creep resistance of polychloroprene are shown. Also, the effect of heat aging on dynamic characteristics and performance are investigated. All the test results are compared with those of natural rubber mounts. The results will show the possibility of the first application of polychloroprene rubber on this type engine mount giving improved fatigue life even after heat aging with balanced dynamic properties.</div>

<div class="htmlview paragraph">A vehicle drifts due to several reasons from its intended straight path even in the case of no steering input. The multibody dynamic analysis of vehicle drift during accelerating and braking are performed. This paper focuses on modeling and evaluating effects of suspension parameters, differential friction, engine mounting and C.G. location of the vehicle under multibody dynamic simulation environment.</div> <div class="htmlview paragraph">Asymmetry of geometry and compliance between left and right side is considered cause of drift. The sensitivities of the suspension parameters are presented for each driving condition. In case of acceleration, the interaction of differential friction and driveshaft stiffness and their influence on drift are also studied. For braking condition, suspension parameters such as initial toe variation of rear coupled torsion beam axle type suspension and kingpin inclination deviation of front suspension are studied including the braking force difference.</div> <div class="htmlview paragraph">The significant factors of drift are ordered and compared for straight line accelerating, driving and braking condition. Using a co-simulation model, it is shown that significant parameters for accelerating condition are driveshaft angle and its stiffness difference between left and right side. It is shown that the location of center of gravity altered by passenger seating position has a great influence on drifting under braking condition.</div>

<div class="htmlview paragraph">The ride and noise behavior of a vehicle is significantly affected by vibration transferred from the engine to the chassis through the engine mounts. In this paper conception and design strategies for engine mount systems based upon calculation and experimental methods are discussed. Analyses for static and dynamic engine loads and for idle shake vibrations are presented. The finite element analysis is applied to optimize a mount's rubber spring geometry. Furthermore, the role of the transfer path analysis in the optimization of an engine mount system is illustrated. Passive and semi-active engine mounts that significantly improve the isolation of the idle shake vibration will be discussed. Finally, fully active vibration absorbers which can be applied to solve noise problems, even at a late stage of a new car development program will be presented.</div>

<div class="htmlview paragraph">The method was established to identify the dynamic stiffness of the engine mount using modal parameters acquired from experimental modal analysis. Vibration tests were conducted using actual large outboard motor the BF225 (165 kW), and the dynamic stiffness of the mounts was identified. The results show that this method can identify the engine mount dynamic stiffness more adequately than the conventional method, even when the engine mounts are subjected to loads corresponding to thrust force or even in the case that the stiffness of the parts supporting an outboard motor is low.</div>

<div class="htmlview paragraph">The Experimental Safety Vehicle powertrain and fuel system developed by General Motors in compliance with Contract DOT-OS-00095 with the U.S. Department of Transportation include several special features: a low engine accessory package to meet the front visibility down angle of 8 degrees, engine and transmission mounting for retention at high decelerations, a light aluminum engine, an over-the-rear-axle fuel tank, and a unique evaporative emission fuel pipe routing.</div> <div class="htmlview paragraph">A comprehensive test program was planned and final testing to validate contract specifications was conducted.</div> <div class="htmlview paragraph"> <div class="graphic-wrapper"><img class="article-image" src="730280_fig0001.jpg" alt="No Caption Available"/></div> </div>

<div class="section abstract"><div class="htmlview paragraph">In the quest for reduced cost and shorter development times for fuel cell systems in industrial applications, two major issues arise. First, the electrochemical behavior of fuel cell systems is inherently difficult to predict. Second, testing fuel cell systems is resource intensive. These issues compound: Setting up an accurate model of a fuel cell system incurs long testing periods for model validation. Further, it does not guarantee acceptable results outside the tested range or for other membrane electrode assembly compositions.</div><div class="htmlview paragraph">To mitigate these two major issues an X in the Loop concept is proposed. Essentially, this is the direct integration of the test sample, here a single fuel cell, into the modelling environment of the whole system. In practice, two strategies with different levels of integration are defined.</div><div class="htmlview paragraph">The first strategy consists of initially deducing the operating parameters of the sample cell from the fuel cell system model. Then, setting them to the sample cell in the test bench. The response of the test sample is finally used to validate the designed system or update the parameters of the fuel cell model.</div><div class="htmlview paragraph">The second strategy is a step further towards the integration of the test sample into the model. Here, the core model of the fuel cell inside the fuel cell system model is completely replaced with the test sample, reducing the need for an accurate electrochemical model while improving the prediction of the behavior of the fuel cell system.</div><div class="htmlview paragraph">Compared to previously proposed testing concepts, here the balance of plants is directly integrated through a digital emulator, leading to a closer representation of the complete system. Furthermore, the test bench results are looped back to the model at run-time leading to a closer match between testing conditions and the real world as well a reduced impact of inaccuracies in the modelling of the fuel cell.</div><div class="htmlview paragraph">On the way to realizing this goal, an experimental test bench capable of showcasing working prototypes of the proposed operating strategies has been built.</div></div>

<div class="htmlview paragraph"><b>THIS paper deals with air-cooled aircraft-engine installations and covers such units as cowling, engine mounts, exhaust systems, carburetor-ice eliminators, oil systems, fuel systems, controls, accessories, and so on.</b></div> <div class="htmlview paragraph"><b>No attempt is made to describe any particularly new ideas in engine-installation design, but rather the paper explains the fundamental requirements for satisfactory operation of Wright air-cooled aircraft engines.</b></div>

<div class="section abstract"><div class="htmlview paragraph">Engine off control is conducted on parallel hybrid vehicles in order to reduce fuel consumption. It is efficient in terms of fuel economy, however, noise and vibration is generated on engine cranking and transferred through engine mount on every mode transition from EV to HEV. Engine crank position control has been studied in this paper in order to reduce vibration generated when next cranking starts. System modeling of an architecture composed of an engine, P1 and P2 motors has been conducted. According to the prior studies, there exists correlation between crank vibration level and the crank angle. Thus a method to locate pistons on a specific crank angle which results in a local minimum of vibration magnitude could be considered. The P1 motor facilitates this crank position control when engine turns off, for its location directly mounted on a crankshaft allows the system model to obtain more precise crank position estimation and improved linearity in torque control as well. For the sake of robustness, a position-speed controller considering active damping has been designed, and verified by simulations on frequency and time domains analyses. The controller suggested in this paper shows better response to load disturbance compared to conventional P-PI position-speed controller, and is able to operate robustly on fluctuating static and dynamic friction of an engine. Vehicle tests have been conducted to prove the control performance, which resulted in 50% reduction of vibration magnitude in average.</div></div>

<div class="section abstract"><div class="htmlview paragraph">15-5PH is a precipitation-hardening, martensitic stainless steel used for primary structural elements such as engine mounts where corrosion resistance, high strength, good fatigue and fracture toughness is required. The material composition is defined in AMS5659M. This alloy can be either Type 1 - vacuum arc remelt (VAR) or Type 2 - electro slag remelt (ESR) and is most commonly heat treated per SAE AMS-H-6875 or AMS2759/3 to condition H1025 (an ultimate tensile strength of 155 ksi [1070 MPa] minimum). Typically material handbooks have limited fatigue data and most data is only for Type 1. Therefore, the fatigue properties of 15-5PH H1025 stainless steel for both Type 1 and Type 2 were determined. The objective of the fatigue testing was to generate a family of S-N curves (maximum stress versus number of cycles to failure) for a series of stress ratios across the entire range of cycles to failure. All test coupons have been made from 5/8″ to 1″ [16-25 mm] diameter bar material with a typical lathe turned surface finish of 40-80 micro-inches [1-2 micro-meters] or a polished surface of 8 micro-inches [0.2 micro-meters]. The machined surface versus the polished surface resulted in a 10% reduction in fatigue strength near the endurance limit. When comparing the family of curves of Type 1 and Type 2 materials no significant differences were found. Therefore, the VAR and ESR Type materials appear to have approximately equivalent fatigue properties based on this set of fatigue data.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Electric vehicles (EVs) differ from internal combustion engine (ICE) vehicles in that they lack a conventional engine and feature an electric drive unit, leading to distinct dynamic behaviours in the powertrain. Additionally, the arrangement of auxiliary components in EVs often differs from that in traditional ICE vehicles, which can sometimes significantly impact safety ratings. This paper examines a case study of a critical failure during a crash test, where displacement of an engine mount arm caused substantial structural intrusion and reduced the vehicle’s safety rating. To address this issue and enhance crashworthiness, a “crash plate” was designed and integrated into the mount system. This solution effectively constrained the mount arm’s movement during impact, preventing the intrusion observed in previous tests. The paper provides a detailed analysis of the crash plate’s dimensions and its relationship to the engine mount, demonstrating its potential for broader application in passenger EVs. This innovative and cost-effective approach significantly improved the vehicle’s crash performance, resulting in a higher safety rating and presenting a new method for enhancing vehicle safety through targeted design improvements.</div></div>

<div class="htmlview paragraph">The objective of the Project is to develop an optimized lead-acid battery solution for HEVs based on a novel, individual, spirally wound valve-regulated lead-acid 2V cell optimized for HEV use and low variability. This cell will be used as a building block for the development of a complete battery pack that is managed at the cell level. Following bench testing, this battery pack will be thoroughly evaluated by substituting it for the NiMH pack in a Honda Insight.</div> <div class="htmlview paragraph">The paper covers the first half of the 3-year project and will describe work carried out in the following areas:</div> <div class="htmlview paragraph"> <ul class="list disc"> <li class="list-item"><div class="htmlview paragraph">Development of cell and battery testing facilities and identification of mechanisms causing cell lifetime scatter.</div> </li> <li class="list-item"><div class="htmlview paragraph">The design and development of the prototype double-ended cell.</div> </li> <li class="list-item"><div class="htmlview paragraph">The development of the battery pack specification and pack design.</div> </li> <li class="list-item"><div class="htmlview paragraph">The development of the battery management system.</div> </li> </ul> </div> <div class="htmlview paragraph">The paper will also give details of the test results obtained on the demonstration vehicle with its original NiMH battery. Arising from these tests, there will be discussion of the merits of bench testing with a cycle derived from ‘real vehicle’ data as compared with the PNGV or Eucar power assist life cycle tests.</div>