Vehicle Gear Research Articles

Vehicle gear shifting strategy optimization with respect to performance and fuel consumption

ABSTRACTBased on the movement resistance forces, the vehicle longitudinal dynamics is related to power demand for a specific route. The vehicle gear shifting influences significantly the acceleration performance and fuel consumption because it changes the engine operation point and the powertrain inertia. This paper presents a study based on the US06 velocity profile that involves high speed and high acceleration phases, where the vehicle performance is limited by both the engine power and the tire traction limit. For improving the vehicle performance without increasing fuel consumption, a genetic algorithm (GA) technique is used.

Design and Analysis of Asymmetrical Spur Gear Drive for Automobile Gear Box Application

This work mainly aims to explore the actual load, fillet and contact stresses induced during a mesh cycle in a spur gear tooth. As the mesh stiffness differs at different contact points along the path of contact, it significantly affects the load sharing between the simultaneously meshed contact pairs hence stresses. Comparative study has been made between existing symmetric spur gear pair used in light motor vehicle gear box and asymmetric spur gear. Finite element multi pair contact model has been used to explore the load sharing behavior and related stresses in this work.

Fault Diagnosis of the Armored Vehicle Gear Transmission System Based on Response Analysis

Gear transmission system is as an important part of the armored vehicle, and its work reliability is directly related to the working performance of the armored vehicle. Based on introducing the need on condition monitoring and fault diagnosis of gear transmission system, the response methods on condition monitoring and fault diagnosis are expressed in the gear transmission system. Finally, an armored vehicle transmission system is as the research object, the test point selection, data acquisition and processing is studied. The paper shows how to use differ method such as the amplitude domain, frequency domain, demodulation analysis and wavelet analysis to extract fault characters and fault identification in the armored vehicle gear transmission system.

3207 操舵反力シミュレータにおけるステアリングギアの摩擦モデルの検討(OS9-1 シミュレータシステムの開発,OS9 ビークルシミュレータの開発と応用,オーガナイズド・セッション(OS))

The steering reactive torque of an automobile is one of the important information for a driver to judge the vehicle behavior and road conditions. This paper describes an empirical model of a friction characteristics of a steering gear for a steering torque simulator. In order to evaluate the friction characteristics, the authors conducted a test using the steering gear of the experimental vehicle. The friction characteristics were evaluated to the angular velocity and the rack force. Moreover, a curved surface approximation were performed to the experimental results using a spline surface, and the most suitable friction model of the steering gear was examined by changed a control point and an order of a spline surface.

Design Principles of Controlling Vehicle Gear Whine Noise Based on Loudness Metric

In-vehicle noise is composed of a variety of tonal (frequency-related) components and the tonal components play an important role in the improvement of sound quality for interior vehicle noise. Among them, gear whine noise is the key contributor to total in-vehicle noise and gain a lot of researchers interest. Through their effort, thespl (dBA)is relatively low. However, customers still perceive the tonal components and complain about the vehicle quality. Therefore a better understanding of how tonal components are perceived is necessary for automotive gear transmission designers. In this study, firstly, gear dynamic behavior is briefly introduced to get the gear noise spectrum. Secondly, human hearing mechanism to different tonal components is summed. Then loudness case studies are conducted. Finally, some basic design principles of controlling gear whine noise are proposed based on the results.

Durability Characteristics Analysis of Plastic Worm Wheel with Glass Fiber Reinforced Polyamide.

Plastic worm wheel is widely used in the vehicle manufacturing field because it is favorable for weight lightening, vibration and noise reduction, as well as corrosion resistance. However, it is very difficult for general plastics to secure the mechanical properties that are required for vehicle gears. If the plastic resin is reinforced by glass fiber in the fabrication process of plastic worm wheel, it is possible to achieve the mechanical properties of metallic material levels. In this study, the mechanical characteristic analysis of the glass-reinforced plastic worm wheel, according to the contents of glass fiber, is performed by analytic and experimental methods. In the case of the glass fiber-reinforced resin, the orientation and contents of glass fibers can influence the mechanical properties. For the characteristic prediction of plastic worm wheel, computer-aided engineering (CAE) analysis processes such as structural and injection molding analysis were executed with the polyamide resin reinforcement glass fiber (25 wt %, 50 wt %). The injection mold for fabricating the prototype plastic worm wheel was designed and made to reflect the CAE analysis results. Finally, the durability of prototype plastic worm wheel fabricated by the injection molding process was evaluated by the experimental method and the characteristics according to the glass fiber contents.

Development of Non-rare-earth Magnetic Gears for Electric Vehicles

This paper presents the development of non-rare-earth magnetic gears for electric vehicles. Firstly, the magnetic gears which adopt either non-rare-earth or rare-earth permanent magnets (PMs) are discussed. Then, by using the finite element analysis, the electromagnetic performance of these magnetic gears are evaluated and quantitatively compared based on the same structure. Also, the natural magnetic characteristics of the non-rare-earth and rare-earth PMs are compared. Finally, a comparison of the cost-effectiveness among different types of PMs is carried out. The results indicate that the non-rare-earth PM material is preferred to the rare-earth PM material for application to magnetic gears.

Multi-Body Dynamics Simulation of A Tracked Vehicle Power Train in Consideration of Multi-Source Excitations

This study proposed a new efficient method to investigate tracked vehicle gear transmission system dynamics applying Finite element theory and multi-body dynamics. Torsional excitation was simulated based on an engine dynamic model by considering flexibility of crankshaft, maximum fire pressure and variable inertia. Gear mesh stiffness coefficient, mesh error excitation, bearing dynamic stiffness coefficient and damping coefficient were numerically calculated. The virtual prototype model of power train system including all aforementioned excitations was constructed. Dynamic responses of transmission shaft working with multi-source excitations were analyzed. The impact of each excitation source was discussed.

Modeling and Co-Simulation for Hydraulic System of Test-Bed of Semi-Automatic Coupler Draft Gear Based on AMEsim/Simulink

When the test-bed tests semi-automatic coupler draft gear of the metro vehicle in the case of maximum lateral swinging angle, it requires a hydraulic motor to move the adjustable bearing base which is linked with coupler draft gear in a certain distance until it achieves the desired Angle. In this article, we adopt the valve-control motor electro-hydraulic position servo control system, in which it has the angular measuring device. Besides we optimize the effection of control system by using the fuzzy strategy. Through the AMEsim/Simulink co-simulation and analysis, the level swinging angle of coupler draft gear shows accurate, reliable and stable, which reaches the expected effection completely. With the more and more complex of the controlled object, this kind of intelligent control strategy gives an effective solution for solving complex problems.

Combined friction induced oscillations of wheelset and track during the curving of metros and their influence on corrugation

Curving of rail vehicles is often connected with vibrations, which can be caused by rail corrugation or friction induced oscillation in the wheel/rail-contact. This paper deals with heavy vibrations at the running gear of a metro vehicle with a typical frequency of 80 Hz on curves with a radius between 50 and 200 m. Specific characteristics of the vibrations are the occurrence by passing over rails without an initial corrugation and the disappearance if the rails are wet. In the curves of the concerned network, corrugation can also be found with a corresponding wavelength on the outer rails, but the inner rails show shorter wavelengths. For a better understanding of the originating process a simulation model is set up using the commercial Multi-Body-Simulation-Software SIMPACK. The model includes the vehicle and the track. After an identification of the undetermined parameters the model shows the same behaviour as the real system. The vibration is characterized by large amplitudes of the normal force in the wheel/rail-contact. The originating mechanism and the determining parameters of the oscillation are identified. Using a simple wear law the possibility of rail corrugation originated by these vibrations can be shown with different wavelengths on the inner and outer rail as observed in the measurements.

Influence of Hardness and Residual Stress on Fatigue Limit for High Strength Steel

For environmental and economical reasons, most vehicles need weight reductions. A useful method to make lighter vehicles is to increase the fatigue limits of vehicle parts. On the previous paper, to prevent the decrease in the fatigue limits of carburized or carbonitrided gears for vehicles by accidental temperature rise while using the gears, a new method, which is treated with the middle temperature tempering before shot peening, was proposed. Based on this consideration, the authors conducted a study by using carburized and carbonitrided specimens on the new method, and evaluated their surface characteristics and bending fatigue limits. The result of the study showed that the fatigue limits of the carburized and carbonitrided specimens processed by the new method achieved 30% and 49% better than those of the specimens assumed accidental temperature rise respectively.

Energy Optimization and Simulation of CJY6470PHEV with Mild Hybrid Strategy

This paper mainly focuses on the energy management system of CJY6470 parallel hybrid electric vehicle (CJY6470PHEV) with the mild hybrid strategy. The energy controller is designed, and the optimum method of the throttle angle and vehicle gear shift, as well as the energy distributing strategy is presented, too. Moreover, the energy management system is simulated according to ECE-EUDC cycles. The results indicate that the energy can be distributed as expected in the system.

Effect of Normalized Microstructure on Micro-distortion of Finished Surface of Gear Steel for Car

In the installed operation of vehicle transmission gears after being normalized,machined and carbonized,noise is produced and it will have adverse effects on the service life of gears.In view of this problem,different microstructures obtained by using two different normalizing processes are studied,and tests are carried out on the surface micro-deformation after machining and surface polishing under the same condition,so as to analyze the cause of difference of micro-deformation.The test results show that the noise produced in the early operation stage of vehicle transmission gears is mainly caused by the deformation that is initiated by the internal stress produced in the machining process of steel gear parts after normalization.Therefore,it is suggested that the vehicle gear blanks should adopt isothermal normalizing process by utilizing the residual forging heat,so as to reduce the friction caused by the deformation in the work pieces operation.

Surface Temperature Calculation and its Application to Surface Fatigue Strength Evaluation

In recent years, power transmission gears for vehicles run at higher speeds and loads and are accompanied by very high surface temperatures. Under such a high surface temperature condition, the surface strength cannot be evaluated correctly only by the use of Hertzian stress. This research attempts to introduce a new surface strength evaluation method considering the surface temperature rise. First, the surface temperatures of rollers under different rolling and sliding conditions are measured using a thermocouple. The effects of load P, mean tangential velocity Vm and sliding velocity Vs on surface temperature are investigated and analyzed. Then, an experimental equation is presented which shows the linear relationship between surface temperature and GRP0.86Vs1.31Vm−0.83 value. Based on the comparisons between calculated and measured tooth surface temperatures, this equation is confirmed applicable to gear tooth surface temperature evaluation as well. A surface temperature index is proposed for surface strength evaluation. The relationship between the surface temperature index and the number of load cycles of the rollers is investigated. The results indicate the possibility to evaluate the surface strength based on the surface temperature.

Optimisation of processing routes for cross rolling and spin extrusion

The trend towards lightweight construction in vehicle manufacturing results in an increased use of hollow shafts in vehicle gear boxes. In order to maintain their competitiveness producers have to reduce their costs and to improve the quality of their products permanently. This publication focuses on near-net-shape and net-shape forming of rotation-symmetrical workpieces by incremental rolling processes. Two methods, cross rolling and spin extrusion, which can be used combined or individually are described with a special focus on spin extrusion. Further more approaches of experimental methods for determination of local forming parameters and different simulation methods are included.

New warm forming processes to produce hollow shafts

In order to maintain their competitiveness, the producers constantly have to reduce their costs and to improve the quality of their products. The trend towards lightweight construction in vehicle manufacturing results in an increased use of hollow shafts in vehicle gear boxes. The publication focuses on near-net-shape and net-shape forming of rotation-symmetrical workpieces by incremental rolling processes. Two methods, cross rolling and spin extrusion, which can be used combined or individually are described. In addition an approach to experimental methods for determination of local forming parameters and different simulation methods will be included.

Test bed for vehicle longitudinal control using chassis dynamometer and virtual reality: An application to adaptive cruise control

In this study, a test bed for vehicle longitudinal control is developed using a chassis dynamometer and real time 3-D graphics. The proposed test bed system consist of a chassis dynamometer on which test vehicle can run longitudinally, a video system that shows virtual driver view, and computer that control the test vehicle and realize the real time 3-D graphics. The purpose of the proposed system is to test vehicle longitudinal control and warning algorithms such as Adaptive Cruise Control (ACC), stop and go systems, and collision warning systems. For acceleration and deceleration situations which only need throttle movements, a vehicle longitudinal spacing control algorithm has been tested on the test bed. The spacing control algorithm has been designed based on sliding mode control and road grade estimation scheme which utilizes the vehicle engine torque map and gear shift information.

Review of solid mechanics in tribology

The study of solid mechanics is essential to the field of tribology, (friction, lubrication and wear). Tribology is of immense economic importance. The potential savings, were tribological principles better understood and applied to friction and wear reduction) may be several percent of the gross national product. Solutions to tribology problems often enable current technologies in a broad spectrum of applications from friction contact in the turbine shrouds of aircraft engines, to bearing contact in motor vehicle gear assemblies, to the sliding contact of magnetic storage disk drives. Conversely, tribology issues, e.g., the coefficient of friction, may impact solid mechanics problems and tangential tractions are essentially free parameters in many cases. Active issues of research in tribology where solid mechanics is applied include: friction and wear in dynamic loading of bearings to extend bearing life; models for contact and thermal stresses of sliding surface asperities; design criteria for magnetic recording heads, and behavior of human artificial joints to extend service life. Countless other applications exist, requiring the development of essential theories of conforming and non-conforming surface behavior. Information such as the frictional response of surfaces in relative motion, and modes of stress and deformation emerges from the fusion of solid mechanics and tribology.

Experimental results of the fatigue crack growth in a gear tooth root

A spur gear pair from the first stage of an industrial vehicle gear box has been subjected to experimental testing. The effects of different load distributions along the gear tooth width on the fatigue crack growth in the gear tooth root are measured on an appropriate testing device. The recorded experimental results are represented using the methods of statistical analysis. Analysing the results proves that different load distributions along the tooth width have a significant influence on the crack growth and thus on the service-life of the gear. Since the experiments provide a three-dimensional experimental analysis of fatigue crack propagation in the tooth root, the results of such analysis can be used for calibrating the numerical simulation of similar problems.

Manufacturing of hollow transmission shafts via bulk-metal forging

More and more hollow transmission shafts are used in all vehicle gears as a result of the demand of light components. Different methods of bulk-metal forging are shown partially in combination with joining and machining processes. They will be discussed with reference to shaping, tolerances and economical aspects.