ELCTRO-MECHANICALLY CONTROLLED CONTINUOUSLY VARIABLE TRANSMISSION SYSTEM FOR PASSENGER CARS (original) (raw)
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Developing and eventually producing an efficient and environmentally friendly transmission technology for passenger cars has always been a major challenge for transmission manufacturers and carmakers, with many different ideas to be considered, studied and tested comprehensively. Continuously variable transmission (CVT) with electro-mechanical actuation system is an innovative idea that has been studied in recent years by many researchers from renowned research institutions with collaboration from relevant companies as a possible solution for an efficient, practical and environmentally friendly automotive transmission. In this paper, a new concept of electro-mechanical actuation system for CVTs is introduced. Firstly, the basic idea of electro-hydro-mechanical actuation system, which is normally used in existing CVTs, is reviewed briefly. Consequently, the working principle together with the fundamental design of the proposed new concept of electro-mechanical actuation system for CVTs is also described. Lastly, potential benefits that can be gained through this new concept are discussed.
Design of Continuously Variable Transmission (CVT) with Metal Pushing Belt and Variable Pulleys
International Journal of Automotive Engineering-ISSN: 2008-9899, 2014
Nowadays, automakers have invested in new technologies in order to improve the efficiency of their products. Giant automakers have taken an important step toward achieving this objective by designing continuously variable transmission systems (CVT) to continuously adapt the power of the engine with the external load according to the optimum efficiency curve of engine and reducing fuel consumption; beside, making smooth start up and removing the shock caused by changing the gear ratio and making more pleasurable driving. Considering the specifications of one of Iranian automaker products (the Saipa Pride 131), a CVT with a metal pushing belt and variable pulleys have been designed to replace its current manual transmission system. The necessary parts and components for the CVT have been determined and considering the necessary constraints, its mechanism and components have been designed.
Analysis, Design and Application of Continuously Variable Transmission (CVT
Continuously Variable Transmission (CVT) offers a continuum of gear ratios between desired limits. This allows the engine to operate more time in the optimum range. In contrast, traditional automatic and manual transmissions have several fixed transmission ratios forcing the engine to operate outside the optimum range. The need for a transmission system and the working principle of CVT has been discussed in depth. An attempt has been made to understand the contribution of Hydraulic Actuators, which is an integral part of a CVT. Furthermore, the question of how and why a Torque Converter has effectively replaced a conventional clutch has been answered. The materials used, constructional aspects and stress analysis of the belt has been discussed in detail. A graphical comparison of fuel efficiency between a manual transmission and a CVT in different high end vehicles is included. Recent developments in clamping force control for the push belt Continuously Variable Transmission (CVT) have resulted in increased efficiency in combination with improved robustness. Current control strategies attempt to prevent macro slip between elements and pulleys at all times for maximum robustness.
Kinematics and nonlinear control of an electromagnetic actuated CVT system for passenger vehicle†
An electromagnetic actuated continuously variable transmission (EMA-CVT) system is developed by two sets of electromagnetic ac- tuators (solenoid) located on primary and secondary pulley. A set of solenoids are attached to the primary and secondary pulley to de- velop the attraction and repulsive forces. The relationships between the speed ratio and electromagnetic actuation and clamping force and output torque of the CVT are established based on the kinematics of the EMA-CVT system. A Fuzzy Logic Controller (FLC) is devel- oped to control the EMA precisely based on the feedback of the RPM sensor and slope sensor. The EMA-CVT performance with con- troller has found 28% more than the performance of the EMA-CVT without controller. The solenoids of the EMA were activated by varying the current supply with the Fuzzy-Proportional-Derivative-Integrator (FPID) to maintain the non-linearity of the CVT in re- sponse of the vehicle traction torque demand. Result shows that the solenoid is able to pull the plunger in the desired distance with supply current of 12.5 amp while push the plunger to the desired distance with 14.00 amp current supply to the windings when the vehicle is considered in 10% grade. The acceleration time of the 1⁄4 scale car has been recorded as 5.5 s with the response of drive wheels torque.
International Journal of Engineering Systems Modelling and Simulation
Vehicle transmission system transfers torque and speed from the power source to drive wheels. Continuously variable transmission (CVT) system offers smooth ratio transition where it improves acceleration performance and reduces fuel consumption. Currently, most of the CVT system is actuated by the internal hydraulic circuit where compressibility of oil introduces non-linearity to the system causing difficulty in controlling CVT response. Therefore, a new free-hydraulic CVT system is developed to overcome the shortcomings in existing CVT. The proposed CVT system is designed based on belt-driven type which consists of two sets of variable pulley. Each set of variable pulleys is actuated by an electric motor using slider crank mechanism. The mathematical modelling of CVT mechanism is developed by using Lagrange formulation. The results from this study show that the simulation model of CVT mechanism can produce good performance behaviour in following desired radius position of the real CVT mechanism.
This dissertation is concerned with the design, analysis and control of a continuously variable transmission and extending its usage to a two wheeler (keeping in the mind the load and working condition of an engine of a two wheelers like Honda active in the case). This transmission is able to provide infinite gear ratios between two constraint limits, without the use of any clutch to disengage the engine from the drive line and hence transfers uninterrupted power to the wheels and mostly runs engine at a constant power. The transmission is, in theory, capable of a better user experience, without the rise and fall in speed of an engine, and the jerk felt when changing gears poorly. Based on the parameters of a two wheeler engine, a CAD model for individual components, like belt and pulley were designed and were further assembled. The control aspects monitoring the pulley movement was shown through a simple hydraulic system managed by an electronic control unit (ECU).
A Review On Continuously Variable Transmissions Control
2010
Over the last two decades, significant research effort has been directed towards developing vehicle transmissions that reduce the energy consumption of an automobile. Good ride performance is one of the most important key attribute of a passenger vehicle. One of the methods to achieve this is by using continuously variable transmission. A continuously variable transmission (CVT) offers a continuum of gear ratios between desired limits, which consequently enhances the fuel economy and dynamic performance of a vehicle by better matching the engine operating conditions to the variable driving scenarios. The current paper reviews the state-of-the-art research on control of friction-limited continuously variable transmissions. As CVT development continues, costs will be reduced further and the performance will continue to improve, which in turn make further development and application of the CVT technology desirable. Challenges and critical issues for future research for control of such CVTs are also discussed.
Control of a Continuously Variable Transmission in an experimental vehicle
2004
This paper focusses on the development of a component controller for a hydraulically actuated metal push-belt Continuously Variable Transmission (CVT), using models for the mechanical and the hydraulic part of the CVT. The ratio controller guarantees that one clamping pressure setpoint is minimal, while the other is raised above the minimum level to enable shifting. This approach is beneficial with respect to efficiency and wear. Vehicle experiments show that good tracking is obtained. The largest deviations from the ratio setpoint are caused by hardware limitations.
Automobile Transmission Systems
— In the current world of automobile, gear shifting system are basically classified into manually and automatic. Gear shifting system plays crucial role in automobile to vary the speed. So automatic gear shifting system is costly than manually gear shifts system but manually gear shifting system is difficult to understand for handicap people or it take physical effort to change gear. To overcome this disadvantage we try to apply touch screen based automatic gear shifting system. In that system by touch on touch screen panel gear is shift. By applying this gear shifting system it gives cost reduction in compare of automatic gear shift system and flexible or simple then manually gear shift system, and by applying this system on automobile it's easier to drive car for everyone. It also reduces the possibility of transmission error of manual gear system. The purpose of this research is to reduce physical effort of human being and they can concentrate only in driving and prevent the accidents. In present report we studied literature review biased on this review we define transmission system and gear shifting mechanism to modify a manual gear shifting mechanism.
Design and control of electromagnetic clutch actuation system for automated manual transmission.
There is a growing interest towards Automatic Transmission in India as it provides better comfort and drivability. But the high cost of this system is limiting itself to be successful in the Indian markets. Due to this, Automated Manual Transmission (AMT) is considered which provides a better solution towards automation as it enhances the drivability and fuel consumption characteristics of a manual transmission at lower costs. However, torque lag and comfort are major issues with AMT which can be addressed by reducing the shift time. In this paper we describe an Electromagnetic Linear Clutch Actuator as a replacement to current electrohydraulic and electromechanical actuator. A control system for the actuator is presented and a clutch engagement strategy is also implemented which reduces the engagement time to 0.78 seconds while reducing jerk and torque lag. The actuator and control system is simulated on a MATLAB Simulink and agreeable results have been obtained.