Study On Inner Bypass Magneto-rheological Damper With Magnetic Bias

As a kind of controllable smart material, magneto-rheological(MR) fluid has gained the extensive attention. With MR fluid, the universal mechanical parts such as dampers, brakes and clutches can be developed, and through them, endow the controlled object with the smart characteristics of dynamical controllability. It is promising to utilize them into the mechanical equipment and national defense industry. The semi-active suspensions for vehicles consists of passive elastic element and MR damper is also make itself research focus, and attracts the eyes of automobile manufacturers. MR damper is a controllable device with MR fluid, it has the advantages of simple structure, quick response, low power consumption large dynamic range and can be simply controlled, it makes a semi-active suspension with sensors and controllers. The sensors feedback the information of vehicle status into the controllers, and a desired damping force is determined by a suitable algorithm, a corresponding excitation current is sent to MR damper to fulfill the target of semi-active control.The MR dampers get their damping force from the pressure drop by forcing the MR fluid flow through the passage with controllable magnetic field. Usually, there is only a passage in the MR damper, which works in the flow mode or mixed mode, and the damping force can be adjusted between the minimum at zero current and the maximum at the saturation current. Consequently, a continuous relative high current should be supplied to MR damper, which leads high power consumption. Once the in the power failure and control failure, only a small force can be supplied to the suspension, which affects the safe steering and makes the driver and occupants, even pedestrians dangerous. In another hand, according to the achievement of researcher, the flow characteristic of MR damper with single passage is also needed to be improved. Based on the analysis, a MR damper scheme integrated with permanent magnet is employed in this paper, which can produce a bias magnetic field in the passage without the applied current and thus bias damping force. The danger of the power and control failure can be avoided by the bias damping force, at the same time, the power consumption is reduced. Furthermore, a new work mode named as inner bypass with two passages is proposed in this paper to improve the flow characteristic of MR damper as our expectation. To sum up, a new type MR damper named as inner bypass MR damper with magnetic bias is proposed, modeled, analyzed, manufactured and tested. The main content of the study is as follows:...