This paper presents a magnetorheological (MR) brake with the intent of overcoming the problems of limited torque density and low manufacturability that conventional MR brakes come across. Firstly, the conceptual design of the proposed MR brake was finalized. High torque density was achieved by using the combined effect of the dual disc-type construction and multipole concept. High manufacturability was attained with a simple and lightweight mechanical construction. It was created with the major components, namely magnetically permeable stator cases, rotor discs, magnetic cores, winding coils, and MR fluid. The computer aided design (CAD) model and analytical models were also developed to study the performance of the proposed brake. Then, the dimensions of the brake were optimized through electromagnetic simulations. Further, the brake performance was simulated using a three-dimensional electromagnetic model. Finally, a prototype of the optimized MR brake was fabricated, and its performance was experimentally validated. It is clear from the computer simulations and experimental test results, that the proposed MR brake has achieved the objective. The maximum torque was 16.5 Nm, and the torque density of 79.3 Nm dm−3 was significantly higher than that of conventional MR brakes. This brake also exhibited a fairly rapid response with a response rate of 90 ms.

Researchers are continuously developing various energy-saving technologies to enhance the internal combustion engine efficiency. Among them, continuous variable valve timing and variable valve lift system is one potential technology. To achieve this ability, a new type of electric valve, known as magnetorheological valve train, was introduced, which is based on the magnetorheological fluid's active behavior. In this study, gasoline engine models are established for dynamic simulations of an engine with the magnetorheological valve train. Volumetric efficiency and performance of the engine with different magnetorheological valve train valve lifts and valve timings at engine speeds between 2000 and 6000 r/min are also analyzed. Simulation results show that, at low engine speeds, the lift of the valve has little effect on the engine performance. However, under high and medium engine speeds, the lift of the valve significantly affects the performance; the smaller the valve lift, the smaller the volumetric efficiency. Likewise, an adjustment of valve opening angle timing to reduce the valve overlap angle effectively increased the engine volumetric efficiency at low engine speeds.

Vehicle manufacturers have been attempting to increase engine efficiency and decrease pollution through various methods. Variable valve actuation technology is one of these methods. Several mechanisms have been established already and have been used to develop this technology. However, these systems have common problems such as complex design, large volume, low response rate, and high-energy consumption. In this study, a novel variable valve actuation device that is compact and requires less energy was developed using magnetorheological (MR) fluid technology. The main components used in this device are an MR valve, passive buffer spring, cam, and rocker arm. This study was divided into three parts. First, an MR valve train was designed. This valve train can be constructed easily, and has fewer hydraulic and mechanical components and consumes less energy than other technologies. Second, the magnetic plate block design was optimized to obtain the required control force at optimal volume and energy. Finally, dynamical simulations pertaining to the springs and the structure were executed to analyze the dynamic condition of the valve. The simulation results indicated that the proposed MR valve could effectively provide functions of variable valve timing and variable valve lift (VVL) by dynamically controlling the external current in the magnetic coil.

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Magnetorheological (MR) fluid devices are widely used in active automotive control applications. However, MR fluid-based valve actuators are not in the limelight. This paper proposes a new flexible valve train with an MR fluid control system; the valve train can enhance the performance of internal combustion engines. A major component of this valve train is the magnetic plate block filled with MR fluid and surrounded by a magnetic coil. This plate block controls the magnetic field in this MR fluid and eventually facilitates flexible valve lifts and valve opening timings. This study overviewed the conceptual design, two-way coupled multi-physics numerical simulations, manufactured an MR valve prototype, and conducted experimental tests on a test bench to understand the real-time performance of the MR valve train. First, computer simulations were performed using a coupled magnetic and thermal multiphysics model to consider the Joule-heating effect of the magnetic coil in the MR magnetic plate block. The simulation results indicated that although the temperature of the MR fluid increased noticeably, it did not exceed the prescribed operating limits. The dimensions of the MR magnetic plate block were optimized. After computer simulations and optimization, a prototype of the proposed MR valve was fabricated and tested to understand its performance in real time. The experimental test results indicated the reliability of the proposed MR valve train in practical scenarios.