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This paper provides an investigation to improve vehicle powertrain NVH performance via modification of excitation and radiation system of powertrain. First of all, considering different excitation mechanisms of the powertrain, the excitation forces are analyzed. The FEM/BEM coupled analysis and the acoustic transfer vector (ATV) calculation as well as panel contribution analysis are applied to investigating the acoustic characteristics of the powertrain. Then a hybrid approach which couples the transmission gear profile modification for attenuating gear system excitation and the transmission housing modification for reducing transmission housing noise radiation is proposed to improve powertrain NVH performance. Experiment validation is conducted in order to assess the modified results. The assessment shows that this hybrid approach can effectively predict and reduce powertrain noise and vibration.

The basic principle of wavelet transform is presented and the method of wavelet theory is used in vibration signal analysis of vehicle in this paper. The vibration signals which generated in the locations such as cab floor, engine, transmission, band spring and frame under the usual work condition are measured by the vibration test system. The vibration signals are decomposed with the principle of wavelet decomposition at level six, and eigenvectors of signal energy are gained. According to the correlation coefficient of eigenvectors of signal energy distribution, two signals correlativity is determined. It could be an effective method that identificate the main vibration source.

In this research the main focus is on reducing the transmitted engine vibration through exhaust line to the passenger cabin in a light commercial vehicle. The main approach is firstly to locate the mountings of the exhaust system based on the results of the modal analysis. Afterwards, the stiffness of the rubber hangers is optimised to minimize the measured vibration in the driver seat rail position. The optimisation approaches are executed considering the design of experiments method. To achieve this, the partial BIW model of the reference vehicle and the powertrain system is generated in FE software. The FE model of the exhaust system is validated by experimental results. In order to define the optimum stiffness for the exhaust rubber hangers, design of experiments method is used. The main candidate parameters for DOE analysis are exhaust rubber hangers in the front floor region in addition to the exhaust flexible joint stiffness.

The purpose of this paper is to study the flow field of a lockup clutch inside a torque converter. The performance of a torque converter has been one of the most important areas of improvement for an automobile equipped with an automatic transmission. Improving the torque converter's performance and efficiency are key contributions to saving fuel, which is an important consideration with the recent increase in environmental awareness. Moreover, the lockup operation- or slipping control- of an automatic transmission is another good opportunity for improving fuel economy.

Manual transmissions, dual clutch transmissions and automatic manual transmissions use a synchronizer mechanism to have smooth gear shifting inside the gearbox and good shift feel inside the driver's cabin. Smooth gear shifting is related to the time required to complete the synchronization process inside the gearbox and a good shift feel related to the force required to shift the gear inside the driver's cabin. Moreover, good shift feel depends on efficiency of gear shifter mechanism, driveline vibrations and double bumps. Transmission gear shifting performance is the major concern area for all automotive and commercial sectors of vehicles. Transmission gear shifting performance in synchromesh gearbox depends on the capacity of synchronizer to produce sufficient frictional torque in required synchronization time and shifting force on the lever.

This paper presents the analysis and experimental validation of c-spring and its stiffness properties in the gear shift synchronizer system. A synchronizer assembly for a transmission comprises of a synchronizer hub carried by a torque delivery shaft and a cone clutch member carried by a gear and a synchronizer blocking ring. The gear shift sleeve is meshing over the teeth of the clutch hub. The c-spring is positioned in the inner circumference of the rim position of the clutch hub and strut keys will be positioned at the slots on the clutch hub, which are usually 120 degree apart. As the sleeve moves while gear shifting, it pushes down the strut keys which compress the C-spring radially inward; this gives the strut load. The strut keys, which are pushed down by the sleeve, will apply force on the c-spring from radial directions. Since the c-spring is in the shape of an arc it is assumed as a curved beam for the analysis.

The scope of tractor usages are widely expanding to various non-agricultural and construction/earthmoving applications like loaders, dozers etc. The tractors with manual transmission driveline subjected to such heavy duty cycles are having conventional dry type clutches in general. These types of dry clutch when operated in such heavy application generate large amount of heat within shorter period of time on the surfaces of friction discs. This increase in disc surface temperature determines not only the level of the friction but also the rate of wear and durability. Number of clutch operation per minute for this application is also increasing to meet the improved productivity requirements. Analysis shows that the rate of heat removal from the friction disc through oil flow system is higher compared to oil immersion type. In this work, an oil spatter concept is designed to provide active circulation of oil to the multi disc clutch during engaged conditions.

Cyclic firing loading conditions coupled with high thermal loads are the main causes for failure of the cylinder head. A complete thermo-mechanical fatigue analysis of a cast aluminum cylinder head should include both high and low cycle fatigue. Reliable nonlinear material behavior, accurate thermo-mechanical stress analysis, and dependable failure criterion are the keys to successful life prediction. The low cycle fatigue is primarily due to thermal stress resulted from repeated start-up and shut-down cycle of the engines. The high cycle fatigue is mainly due to the firing loads, as amplitude stress, accumulated to the mean stress due to the thermal load. In this paper the required CAE simulations for high/low cycle fatigue of cylinder head will be discussed.

In this study, an Electro-pneumatic shifting system (E.P.S) has been designed to install on manual transmissions to make the selecting and shifting process faster and more reliable compared to manual systems. Shifting mechanism of a six speed gear box has been improved by using two tandem pneumatic cylinders, position sensors, pneumatic valves, and a controlling board based on AVR microcontroller. The central processing unit uses an electronic control system to provide the optimized operation of shift mechanism. This system can be easily adjusted in order to install externally on manual transmission systems without any changes on housing and transmission shift links.

The demand of gear shift quality in vehicles has increased considerably in the past few years. The gear shift is the key interface between driver and vehicle transmission. The essential criterions for the operating quality of the gear shift is the operating force and feel on the gear shift knob at each stage of gear shift, starting from start of gear shift to the end of gear shift. This paper deals with techniques to reduce secondary force due to synchronizer sleeve hitting on dog ring at the end of gear shift which is also known as Double Bump. The double bump ratio should be less than 0.4 to achieve the best in class shift feel for passenger car segment. Normal driver will not feel if double bump ratio is less than 0.6. Inertia mass mounted on shift system of manual transmission helps to generate momentum at the end of gear shift to nullify the double bump force.

This research project compares the in-use and laboratory-derived fuel economy of a medium-duty hybrid electric drivetrain with “engine off at idle” capability to a conventional drivetrain in a typical commercial package delivery application. Vehicles in this study included eleven model year 2010 Freightliner P100H hybrids that were placed in service at a United Parcel Service (UPS) facility in Minneapolis, Minn., during the first half of 2010. These hybrid vehicles were evaluated for 18 months against eleven model year 2010 Freightliner P100D diesels that were placed in service at the same facility a couple months after the hybrids. Both vehicle study groups use the same model year 2009 Cummins ISB 200 HP engine. The vehicles of interest were chosen by comparing the average daily mileage of the hybrid group to that of a similar size and usage diesel group.

With growing fuel prices and global warming, fuel economy improvement and reduced emissions are becoming order of the day. Automobile manufacturers around the world are in increasing pressure to achieve the same, also keeping in account the stiff timelines required in the product developmental cycle. Condensed duty cycle that is representative of several days of actual real life running is developed for quicker fuel economy tuning on a chassis dynamometer. This paper presents a new methodology to obtain a synthetic drive duty cycle, which matches engine operating conditions of the actual real life cycle accurately and thereby providing a more accurate match in fuel economy. Drive duty cycle (vehicle velocity profile) used in this study is extracted from the instrumented vehicle in the real traffic condition (peak/lean hour) of major cities in India at different location/load conditions. Each recorded trip is further divided into micro trips.

The paper addresses some aspects of an ongoing research on a commercial compact excavator. The interest is focused on the analysis and modelling of the whole hydraulic circuit that, beside a load sensing variable displacement pump, features a stack of nine proportional directional control valves modules of which seven are of the load sensing type. Loads being sensed are the boom swing, boom, stick and bucket, right and left track motors and work tools; instead, the blade and the turret swing users do not contribute to the load sensing signal. Of specific interest are the peculiarities that were observed in the stack. In fact, to develop an accurate AMESim modelling, the stack was dismantled and all modules analysed and represented in a CAD environment as 3D parts. The load sensing flow generation unit was replaced on the vehicle by another one whose analysis and modelling have been developed using available design and experimental data.

Global demand for diesel fuel has predominantly driven the Commercial Vehicle industry to seek out fuel consumption reduction technologies to integrate into their products in order to provide value to their customers. Since air generation and use directly affect fuel consumption, active management of these systems provides a new avenue to achieving future fuel and green house gas (GHG) emissions requirements. Using a turbocharged compressor coupled with a clutch mechanism delivers air at maximum efficiency while simultaneously removing parasitic losses during an inactive state. The electronic air dryer monitors vehicle status and actively manages the charging and regeneration activities to minimize waste. Lastly, the use of an engine air boosting device enables both steady state and transient savings by means of driveline modifications such as adaptive shifting and rear axle ratio changes without the associated dynamic performance degradation.

This paper investigates the development of a deaeration device to remove nitrogen from the hydraulic fluid in hydraulic hybrid vehicles (HHVs). HHVs, which use accumulators to store and recycle energy, can significantly reduce vehicle emissions in urban delivery vehicles. In accumulators, nitrogen behind a piston cylinder or inside a bladder pressurizes an incompressible fluid. The permeation of the nitrogen through the rubber bladder into the hydraulic fluid limits the efficiency and reliability of the HHV system, since the pressure drop in the hydraulic fluid can in turn cause cavitation on pump components and excessive noise in the system. The nitrogen bubbles within the hydraulic fluid may be removed through the employment of commercial bubble eliminators if the bubbles are larger than a certain threshold. However, gas is also dissolved within the hydraulic fluid; therefore, novel design is necessary for effective deaeration in the fluid HHV circuit.

This paper describes the results of a study focused on the mathematical modeling of an excavator hydraulic system. From the viewpoint of designing and tuning an efficient control system, the excavator is a very complex nonlinear plant. To design and tune such a complex control system an extremely good nonlinear model of the plant is necessary. The problem of modeling an excavator is considered in this paper; a nonlinear mathematical model of an excavator has been developed using the AMESim® modeling environment to replicate actual operating conditions. The excavator model is described by detailed models of the main pump, valve block and kinematic model. The objective of this research is to develop a complete simulation model of an excavator with the capability of reproducing the actual characteristics of the system. The model could then be used as a platform to facilitate the study of alternate control strategies towards energy efficient systems and new controller designs for HIL.

This paper presents an experimental study of external gear pump efficiency based upon an analysis of the Stribeck values. The volumetric, mechanical, and overall efficiencies of a variety of external gear pumps were measured under steady state conditions. Straight grade antiwear hydraulic fluids were evaluated at 50°C and 80°C. Stribeck values for mechanical, volumetric, and overall efficiency were compared to classic pump efficiency curves. The experimental curves for pump volumetric and overall efficiency were consistent with the classic pump efficiency model. Mechanical efficiency diverged from model behavior at low Stribeck numbers; declining at low speeds and high pressures as contact conditions transitioned from the hydrodynamic to the mixed-film lubrication regime. Lubrication of external gear pumps can be enhanced by using hydraulic fluids that optimize the Stribeck value. A simple expression for relating the Stribeck number to volumetric and mechanical efficiency is presented.

Embedded software development has been dramatically improved with model based design and auto code generation tools. However, the development process of complicated embedded control systems still faces great challenges. Modern embedded control becomes so complicated due to sophistical control hardware and control optimization driven by competitive pressure and regulations. For example, engine embedded control development has to consider global emissions and On Board Diagnostics (OBD) regulations besides various vehicle platforms for the global market. This paper presents several design aspects for complex embedded control software architecture including component based design, component management, and software validation. The paper discusses several software architecture design ideas and analyzes their design benefits and disadvantages. Finally, the paper proposes a software architecture design and provides a design example.

Designing a cabin tilting system for Light Commercial Vehicles using a single torsion bar becomes challenging considering the operator safety and stringent design weight targets. Performance of a good tilting system entirely depends on cabin mass and location of centre of gravity with respect to (w.r.t) to tilting pivot point. Cabin Mass and COG location are very difficult to estimate while designing a new cabin as it is dependent on the maturation of all other cabin aggregates and also the accessories added by the customer. Incorporation design parameter changes like increasing cab tilting angle and increasing torsion bar length, in the later stages of product development, becomes expensive. The objective of this paper is to come up with an optimum design of a single torsion bar tilting employing “Taguchi optimization” for deciding the optimum levels of control factors, which ensures desired performance (i.e tilting effort vs.

This paper presented a brief derivation of the energy dissipation by vehicle shock absorbers. Analysis between energy dissipation and damping coefficient, the road displacement power spectral density, the vehicle speed and the tire stiffness was carried out. Then an energy recovery scheme was put forward, and the bench test proved that the energy harvest scheme is feasible. In the end, this paper provided detailed derivation of the characteristics of the hydraulic electromagnetic energy-regenerative shock absorber, which increases its feasibility and practicability.