Research On Magnetorheological Valves And Magnetorheological Hydraulic Actuators With Damping Property

Hydraulic actuator systems are not only widely used in the fields of mechanical machining, automotives and civil infrastructures, but also successfully used in aerospace, aviation, and military products. As one of the key control components in a hydraulic actuator system, hydraulic valves will affect the static and dynamic characteristics and the reliability of the hydraulic system. Due to the moving mechanical parts, the conventional mechanical valves not only incur the following problems such as the structural complexity, large volume size, high precise machining, easy wear-out, and high cost, but also incur the control difficulty, slow response, high noise, and low reliability. In order to improve the performance of the hydraulic actuator systems, it is urgent to find one kind of hydraulic valves with simple structure, high reliability, easy controllability, and high response. In recent years, especially with the continuously deep research of the smart materials and structures, the research and application of the smart actuators based on the smart fluids are paid much attention to. Magnetorheological (MR) fluids, as one typical representative of the smart fluids, are successfully used to develop various controllable devices. In this dissertation, the principle and structure of the MR valve with both annular and radial damping gaps are proposed and studied, the MR hydraulic actuator with damping property based the newly realized MR valves are proposed and realized. Because the MR valves can be controlled by electric signals and exclude the moving mechanical parts, the MR valves not only possess the simple structure, high reliability, but also possess the easy controllability and rapid response, which will improve the property of the MR hydraulic system. The major research works completed in this dissertation include: 1. The principles and structures of both the MR valve with annular damping gaps and the MR valve possessing simultaneously annular and radial damping gaps are proposed and realized. The characteristics, the material selections, and the design and calculation of the magnetic circuits of the newly proposed MR valves are also explored. 2. The magnetic circuits of the proposed and developed MR valves with two different kinds of damping gaps are simulated using ANSYS/EMAG and the distribution of the magnetic flux and the relationship of the magnetic flux density with the driving current of both MR valves are compared. The rationality of the structures and the magnetic circuits of both MR valves are validated by the simulation results. 3. The mathematical models for both MR valves are established on the basis of the structural design and magnetic circuit simulation. Based on the established mathematical models, the simulation models for both MR valves with MATLAB/Simulink are established and the properties of both MR valves are simulated. The simulation results indicate that the efficiency of the MR valve possessing both annular and circular disk-type damping gaps is superior to that with annular damping gaps with the same magnetic flux density and outer radius of the valves. 4. The test setup for both MR valves based on dSPACE is established and the testing results show that the pressure drop induced by the MR valve with both annular and radial damping gaps is larger than that by the MR valve with annular damping gaps under the same condition. It is worth to be noted that the needed driving current to the MR valve with both annular and radial damping gaps is less than that to the MR valve with annular damping gaps under the cut-off state of the MR valves, which show that the MR valve with both annular and radial damping gaps consumes less energy. In general, the testing results show the established mathematical models of the MR valves are benefit to the design of the MR valves. 5. The MR hydraulic actuator based on the MR valve with annular and radial disk-type damping gaps are explored. The formulations to predict the damping forces based on axes symmetry model are derived using the Newton model and Bingham model. The behavior and performance of the MR valve with both annular and radial damping gaps is expressed in terms of non-dimensional parameters and the efficiency of the MR hydraulic actuator system with the MR valves with both annular and radial damping gaps in Wheatstone bridge network is studied 6. The prototype of the MR hydraulic actuator with the MR valves with both annular and radial damping gaps in Wheatstone bridge network is established using the rapid control prototyping (RCP) technique based on dSPACE. Based on the established prototype, the test setup for the MR hydraulic actuator via dSPACE is also established. The research works in this dissertation establish the theoretical foundation for the research and development of the MR hydraulic system and especially benefit to the research and development of MR valves.