Browse Topic: Magnetic clutches
Clutches are mechanisms used for coupling between shafts in order to transmit torque from one to the other. This coupling is made mechanically by friction between the parts with a high friction intermediate material. In this process, the slippage between the parts becomes a source of heat that makes the system temperature to raise up to high values. Under high temperature, the capacity of torque transmission of the clutch can be reduced by the variation of the effective contact diameter, once the contact region of friction change as the temperature is rising. This is caused by the thermal-displacement effect induced by the friction. The torque capacity also can be affected by the friction coefficient that varies with the temperature. Therefore, in order to design an optimized system, it is necessary an analysis of the parts and materials under the influence of temperature changing. This work proposes a simulation methodology for the evaluation of tensions and deformations influenced by the friction heat generation through a test of 15 uniform load cycles of energy by 30 kJ converted into thermal energy. The mechanical coupling dynamic is modeled in the Matlab software and the results are fed into the Abaqus, a Finite Element software, where the thermal dynamic is calculated to result the stresses and strains. The proposed methodology was applied in a generic magnetic clutch where the thermal distribution of the clutch is observed according to the load cycles. At the end of these steps it will be possible to improve the design of clutches aiming the optimization of the system.
This paper describes the simulation, design, and testing of a mechanically supercharged 2.4L I-4 gasoline direct injection engine with Miller cycle late intake valve closing and high geometric compression ratio. Engine downspeeding is also achieved through modified transmission gear ratios. A 3.3L naturally-aspirated V6 engine was chosen as the benchmark for comparison. Intended vehicle application is a mid-size passenger car or small/mid-size CUV. The CAE tool GT-Power was used for component selection and air path development. The powertrain simulation model was then exercised to show both improved fuel economy and performance compared to the V6 baseline engine. The design of a bespoke integrated supercharger with magnetic clutch, charge air cooler, and intake manifold was made and procured. A large new software aggregate was ported into an existing production ECU with modified internal circuitry. Volumetric efficiency was calibrated using automated engine mapping techniques and software. Data reduction methods compiled the raw outputs into a point-slope format. A full factorial design of experiments yielded models for the most potent calibration areas. Engine dynamometer results show promising fuel economy improvement under simulated FTP drive cycles. Development for supercharger clutch control and in-vehicle testing is currently in progress.
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