Automotive Manual Transmission Research Articles

Method using torque mode of motor for the shift of two-speed planetary CLAMT in bilateral electric drive tracked vehicle

For the shift control of clutchless automotive manual transmission (CLAMT) in electric vehicle, great difficulty is caused by the high level of precision and rapidity requirements of the speed and mode response of motor as well as the position response of gearshift sleeve, especially when confronted with off-road environment. To overcome the difficulty and achieve fast shift, a practical control method is proposed and applied to two-speed planetary CLAMT for off-road tracked vehicle with bilateral electric drive system, wire control system and unmanned driving purpose. In shift process, the method lets motor be controlled by applying torque mode and constant torque during active speed adjusting phase, lets gear engaging phase be started at the time when transmission ratio is regulated beyond a certain value close to target gear ratio – that is, at the time when the approach of synchronized state is achieved, lets synchronizer make a help for precise gear synchronization. Theoretical analysis of gear synchronization process is carried out. By increasing the level of motor torque, the duration of active speed adjusting phase can be obviously shortened. With the approach of synchronized state judged by using transmission ratio margin of small fixed positive value for reference, gear engaging phase can be achieved quickly. Off-road experiments show good performance of the shift control method. Experimental results and phenomena are discussed in detail for further and better understanding of real shift process.

Effect of bearing thermally induced preload on the efficiency of automotive manual transmission under RDE

In order to calculate the efficiency of an automotive manual transmission, taking into consideration the effect of its most power consuming components – gears and bearings – as well as the interactions between them is of high importance. In this paper, a dynamic model has been developed which can predict the frictional losses of a complete gearbox as a system and, thus, its efficiency. The effect of temperature on bearing preload is also considered and taken into account from a system perspective identifying its effect on the bearings frictional losses (as well as the overall efficiency). The operating conditions used are snapshots of the Real Driving Emissions driving cycle, which is a standard metric for automotive manufacturers. Results show that doubling the temperature can lead to 120% increase of the bearing losses and up to 140% increase of the total transmission losses. The effect of the variation of operating conditions (velocity and torque) is also taken into account. The novelty of this paper lays in the development of a dynamic model which takes into account the performance of a complete gearbox under transient operating conditions, as well as the interaction among its main components and the ability to make changes on the influencing factors of transmission efficiency so that their effect on the complete gearbox efficiency can be tracked. This has not been yet reported in the relevant literature which mainly focuses on the influencing factors of transmission power loss and efficiency experimental measurements under various operating conditions for gear pairs instead of complete gearboxes.

수동변속기용 비접촉식 변속단 감지센서 개발

The present paper relates to a development of the Gear Detection Sensor for automotive manual transmission. To detect air gap from control finger to detecting zone of sensor based on non-contacted method, permanent magnet and linear type Hall IC are mounted in this sensor. Control finger is machined to 3 step heights to detect 3 gear stages such as In-Gear, Normal and Rear. After conducting actual experimentation based on exclusive Jig and FEM, it is described to consider possibility for automotive application of Gear Detection Sensor.

Kinematic and Dynamic Simulation of Automotive Manual Transmission

In the study, a five-speed manual transmission of commercial vehicles is modeled and assembled with three-dimensional (3D) software SolidWorks. In order to analyze the kinematic and dynamic performance of the manual transmission, its 3D model is imported into the software ADAMS and the Hertz elastic contact theory is applied to calculate the contact force and deformation of the meshing gears. Finally, the speed and meshing force of the meshing gears have been obtained, which are consistent with the actual situation. This method can provide guidance for the design of the key components of the transmission, and thus can shorten the development cycle and reduce the development cost of the transmission.

An Experimental Investigation of Power Losses in Manual Transmission Gear Box

In this study, the influence of a variety of operating conditions on the power losses and efficiency of an automotive manual transmission was investigated experimentally. An experimental methodology was developed to measure power losses of a manual transmission under both loaded and unloaded conditions while all operation parameters were controlled tightly. A set of fixtures and instrumentation were designed and implemented to apply the experimental methodology to a five-speed, manual transmission from a front-wheel-drive passenger vehicle. Experimental parametric studies were performed to quantify the influence of operating conditions including load, oil viscosity and oil volume on load-dependent (mechanical) and load-independent (spin) power losses of the transmission. Analysis of the power loss data revealed that all three of these parameters influenced the components of the transmission power loss significantly, and specific conclusions were drawn in order to aid attempts to increase overall transmission efficiency. The experimental database formed as a result of this study is extensive so as to allow a complete validation of transmission power loss models.

Experimental investigations about the influence of oil lubricant between teeth on the gear rattle phenomenon

The article describes an experimental investigation into the “gear rattle” phenomenon in automotive manual transmissions with a special focus on the influence that lubricant oil may have in reducing this undesirable event. The experimental analysis has been conducted in order to validate a theoretical model developed by the authors that accounts for the presence of oil between the meshing gear teeth of unloaded gear pairs during the no-contact phase. An original measurement technique has been adopted for the tests that consist of the acquisition of the angular relative motion of a gear pair by two high resolution encoders. The experimental test rig designed for this analysis offers the possibility of varying the distance between the wheel axes so that the influence of the backlash variation on the rattle phenomenon can be investigated. The paper presents the results of a series of experiments conducted on helical gear pairs from an automotive gear box in the “idle gear rattle” condition by varying the lubrication mechanism. The experimental results show good agreement with the expectations provided by the theoretical model.

A gear rattle model accounting for oil squeeze between the meshing gear teeth

In this paper a non-linear one-degree-of-freedom model for analysis of gear rattle vibrations in automotive manual transmissions is presented. In order to take into account the damping effects owing to the oil in the gap between two teeth of a meshing gear, a simple one-dimensional model for the oil-film squeeze effects is proposed. The squeeze model assumes that the damping force is proportional to the oil viscosity and to the extension of the oil film in the plane of curvature of the teeth, which may depend on the lubrication conditions (dry sump, splash, bath). The results provided from several numerical simulations, carried out with reference to helical involute tooth pairs, confirm the capability of oil in reducing the high-frequency vibrations subsequent to the impact between the teeth. In particular, the influence exerted by oil viscosity and gap extension on the rattle characteristics is investigated through the analysis of the transient response of the driven gear by imposing a harmonic motion to the driving gear.

Numerical Modelling and Analysis of Automotive Transmission Rattle

This paper describes a research work on modelling and numerical analysis of torsional vibration in automotive manual transmissions. The focus of the effort is on a decoupling procedure for the numerical analysis of gear rattle. The power train model is specified into a linear sub-system and a non-linear sub-system that includes the strong nonlinearities of gear backlash and multi-stage clutch stiffness. The weak coupling of the sub-systems is then exploited for efficient numerical analysis. It is shown that the decoupled model yields an acceptable accuracy with a significant gain in computational efficiency when using an algorithm of numerical integration of stiff differential equations or a finite element in time algorithm. Numerical simulation results for a Daimler-Chrysler vehicle power train are given to illustrate the effectiveness of the proposed scheme.

Influence of addition of titanium to stainless steel

The winners of the Japan Powder Metallurgy Association's (JPMA) 2000 awards expand the use of powder metallurgy (PM) technology in automotive manual transmissions, gas-fuelled engines, cellular phones and computers. The awards also include a world first for the series production of PM titanium automotive engine valves. The prizes recognize innovation in parts design, new materials and powders, and process development.

Gear rattle modelling and analysis for automotive manual transmissions

This paper describes a model for torsional vibration of automotive manual transmissions and its subsequent analysis. The model is developed for the purpose of analysis and prediction of gear rattles. Efforts have been made to include as many components of power train as possible and to study the rattle responses of all the speeds. Elements of the model include engine, clutch, flywheel, laden and unladen gears, and shafts. Numerical methods available in MATLAB for solving the ordinary differential equations are employed for the dynamic analysis. Results are presented to show the effectiveness of the modelling and analysis scheme. A software package has also been developed to build and analyse any power train model. The package was used to analyse the Daimler-Chrysler T350 transmission and the results are presented in the paper. It is shown that the gear rattle may exhibit three major modes of double-sided, single-sided or irregular impacts. A rattle index has been used to compare the rattle levels produced by different gear pairs. This could be very useful for the purpose of tuning the clutch for the best rattle noise reduction.

Japan's award winners expand the reach of PM

The winners of the Japan Powder Metallurgy Association's (JPMA) 2000 awards expand the use of powder metallurgy (PM) technology in automotive manual transmissions, gas-fuelled engines, cellular phones and computers. The awards also include a world first for the series production of PM titanium automotive engine valves. The prizes recognize innovation in parts design, new materials and powders, and process development.

An Analytical Study of Automotive Neutral Gear Rattle

A reduced order nonlinear model of an automotive manual transmission is presented and the neutral rattle case is analyzed. For a single frequency excitation and primary resonance, approximate analytical solutions are developed for a multi-degree-of-freedom model of a transmission using the method of harmonic balance. Based on these solutions, a simplified set of equations is developed for the study of neutral gear rattle and the use of these equations for design studies is illustrated. The nonlinear frequency response characteristics are discussed and the results are compared to similar studies described in the literature. It is shown that this analysis provides an improved understanding of the neutral gear rattle problem as well as an analytical basis for the nonlinear behavior reported in the literature.