Gear Shift Quality Research Articles

Improving the gearshifts events in automated manual transmission by using an electromagnetic actuator

The existing electrically automated manual transmission employs DC motors to carry out gearshift events. It is relatively complicated and has potential to be improved both in structure and transmission efficiency. A novel gearshift system that utilizes a 2-DOF electromagnetic actuator to realize the automation of gearshift is proposed. The structure and working principle are introduced, and the coupling system model of the actuator is developed to investigate its characteristics. The results show that the utilization of the electromagnetic actuator in automated manual transmission gearshift system is appropriate. Multi-stage control strategy including PID algorithm and optimal control is introduced to improve the gearshift quality. A look-up table is developed to adjust the peak force of synchronization process according to the working condition. Finally, the conceptual gearshift system and the control strategy are verified on a test bench. The results show that the controller can adjust the peak force of the synchronization process timely and the designed control strategy achieves the compromise of indexes of gearshift quality. The novel gearshift system is technically feasible.

Measurement and Modeling of Perceived Gear Shift Quality for Automatic Transmission Vehicles

Measurement and Modeling of Perceived Gear Shift Quality for Automatic Transmission Vehicles

Shift Performance Test and Analysis of Multipurpose Vehicle

This paper presented an analysis of the gear shifting performances of a multipurpose vehicle transmission in driving condition by Ricardo's Gear Shift Quality Assessment (GSQA) system. The performances of the transmission included the travel and effort of the gear shift lever and synchronizing time. The mathematic models of the transmission including the gear shift mechanism and synchronizer were developed in MATLAB. The model of the gear shift mechanism was developed to analyze the travel map of the gear shift lever and the model of the synchronizer was developed to obtain the force-time curve of the synchronizer during the slipping time. The model of the synchronizer was used to investigate the relationship between the performances of the transmission and the variation of parameters during gear shifting. The mathematic models of the gear shift mechanism and the synchronizer provided a rapid design and verification method for the transmission with ring spring.

Shifter Fork Stiffness Correlation to Gear Shift Quality

Shifter Fork Stiffness Correlation to Gear Shift Quality

Antishudder Gearshift Controller Design for Automatic Transmission

To enhance gearshift quality and the durability of frictional elements, an antishudder gearshift controller design for automatic transmissions is discussed, which both makes turbine speed precisely track the desired trajectory and suppresses the output shaft oscillation. Moreover, these targets are achieved by clutch pressure control only. This paper also considered the model uncertainties of the electrohydraulic control system and disturbance, which are represented by two types of friction characteristics related to temperature, as well as age-related deterioration in automatic transmission fluid and the friction material. Sliding-mode control under the frame of the backstepping technique is used to make the controller robustly adapt to various conditions. In this paper, MATLAB is utilized as the programming environment, and the powertrain system is analyzed in the control-oriented sense. Last, the simulation of 1-2 upshift is illustrated to verify the validity of the proposed controller.

Analysis and simulation of a torque assist automated manual transmission

The paper presents the kinematic and dynamic analysis of a power-shift automated manual transmission (AMT) characterised by a wet clutch, called assist clutch (ACL), replacing the fifth gear synchroniser. This torque assist mechanism becomes a torque transfer path during gearshifts, in order to overcome a typical dynamic problem of the AMTs, that is the driving force interruption. The mean power contributions during gearshifts are computed for different engine and ACL interventions, thus allowing to draw considerations useful for developing the control algorithms. The simulation results prove the advantages in terms of gearshift quality and ride comfort of the analysed transmission.

Optimisation of gear shift quality: By Means of Simulation

Over the last 15 years Ricardo has developed a process that utilises a range of state of the art tools to solve and prevent gearshift quality problems. Ricardo has successfully applied these tools for OEM’s, Tier 1 suppliers, synchroniser and synchroniser friction material suppliers and lubricant suppliers. This has been achieved by using a combination of advanced dynamic simulation, practical in-vehicle development and the Ricardo „GearShift Quality Assessment“ test and analysis system. This article describes the tools and processes used by Ricardo to solve and prevent gearshift quality problems.

GUDA-4 MULTI CONE SYNCHRONIZER DYNAMIC MODELING AND EXPERIMENTAL BENCH TEST RIG TO IMPROVE MANUAL TRANSMISSION SHIFTABILITY(GEAR UNIT DESIGN AND APPLICATIONS)

Multi-body synchronizer and selector mechanism model has been developed and experimentally validated to improve gearshift quality in manual transmissions. The model has been implemented in a commercial multibody program (ADAMS), and it includes simulation of detent mechanism, contact forces on the sleeve, blocker and engagement teeth, as well as jamming on the synchronizer rings. Single, double or triple cone synchronizers can be modeled. The whole selector mechanism from the fork acting on the sleeve to the lever is modeled, including bowden cable. Extensive experimental vehicle and bench tests have been performed to validate the model. To overcome the problem due to the variability of the force and velocity applied by the driver, a dedicated system has been used in bench test rig, where hydraulic force actuator gives repeatable and constant input directly into gearbox. Displacements and axial forces acting on sleeves have been measured on the "Manual Transmission Shiftability Bench". Comparison between numerical results and experimental measures shows good agreement after a preliminary work aimed to rate a number of model parameters (equivalent cone friction, contact stiffness and damping) whose values are not easily available. The model gives a good understanding of gearshift problems, such as double bump and jamming on synchronizer rings, allowing to investigate many potential solutions. Design parameter analysis have been performed for gearshift quality improvement, such as reduction of synchronization effort and duration, and minimization of engagement force (double bump effort). Proposed solutions for multi-cone synchronizer and internal selector mechanism have to be successively tested on the bench. The paper describes the main features of the model together with a discussion on the numerical and experimental results, and new proposals to improve gearshift quality in manual transmissions.

A systems modelling and simulation approach to gear shift effort analysis

Synchronized gear shift quality is a major contributor to vehicle refinement. A number of papers have recently presented analytical methods for studying shift quality. However, in these papers consideration is given to the transmission in isolation from the dynamics of the powertrain and the external environment. In order to obtain a more holistic understanding of the phenomena, the use of a systems modelling and simulation strategy is adopted. A mathematical model of a conventional transmission is formulated. The model is employed in conjunction with the shift quality measures to provide numerical information relating to how the gear shift performance of a vehicle is affected by external factors acting on the transmission and also to variations of pertinent transmission parameters. Particular consideration is given to operation of the vehicle in an off-road environment and variations in input pinion inertia.

An Investigation into Objective Measures of Gear-shift Quality

During any synchromesh development programme, reliable methods for evaluating and assessing the gear-shift quality are necessary. In order to overcome the reliance on a trained driver and associated subjective judgement, methods have been investigated to describe the gear-shift characteristics using objective, rather than subjective measures This paper describes the measurement and calculation of objective measures that relate to perceived shift quality. Examples are given on the use of these measures to evaluate the effect of production variability on shift quality, and to allow comparisons of shift quality to be made between competitive vehicles