The Design And Characteristic Simulation Of Electromagnetic Hydraulic Mount

At present, more and more requirements were put forward to making the ride comfort better. It has been the main criteria of the car. And the criteria have also become a focus for each automotive factory. The vibration is the critical aspect which affects the comfort in the car. Therefore, we should try our best to control the vibration and make the effect minimum in terms of the comfort. The engine is one of the most important sources of noise and vibration for automobiles. So the isolation of engine vibration is critical to the improvement of NVH characteristics. A mount is a bridge which connects engine with chassis. High performance engine mounts can not only reduce the vibration that is transmitted from the engine to the vehicle chassis, eliminate"booming"sound inside the car, but also provide the engine-transmission assembly superior protection.The chief function of engine mounts is to support the weight of the engine and effectively isolate the vibration. Because conventional elastomeric mounts and hydraulic mounts are unable to satisfy these two aspects synchronously, people advance a new concept that is called active mounts. As the active mounts can counteract the force from the engine to the chassis through an actuator which can supply dynamic force that we can make the vibration minimum .Theoretically, we can counteract the vibration of the chassis thoroughly.The active control hydraulic mount with electromagnetic-actuator in the paper consists of intrinsic passive hydraulic mount and electromagnetic-actuator. Because hydraulic mounts have superior isolation ability in the low frequency range, and electromagnetic actuator can provide favorable active vibration control performance in relative high frequency range, so the active engine mount can isolate the vibration of engine in much wider frequency range.Firstly, it introduces the background, history and production of the mounts in the paper, in which it also advances the ideal performance and value of the mounts. The representative structures of different active mounts have been introduced in detail. So do the illustrations of the mounts about the structure characteristics.Secondly, several different actuators have been introduced in the active vibration control. Some of the ones are compared with their characteristics and their applying domain. In the meantime, the electromagnetic-actuator which is the chief content of the paper is depicted in detail. To take the structure model into consideration, the physic model and mathematic model through which we deduce the transfer function model are built. In order to design the actuators and select the parameters, some key factors that influence the performance of actuators are analyzed.Thirdly, two kinds of active control named open loop and closed loop are introduced, as far as the ways for vibration isolation. The control schemes for active vibration isolation can be classified into two categories: feedback and feedforward control. The main idea of this part is about Least Mean Square(LMS) algorithm. Through deducing the correlative formulae, we get arithmetic formulae in practice. As the same time, the development and improvement of LMS algorithm is depicted as the characteristics and stability of LMS algorithm is analyzed.In the following part, the reason for engine vibration is analyzed, as far as the theory of active vibration isolation is introduced in detail and there also some correlative formulae. Through the upper analysis, we know the source of vibration from the four-stroke engine of four-cylinder is two-step inertia force. On the basis of the structure of the electromagnetic-actuator, we build the physic model and mathematic model. The two models are build on the assumption that the liquid in both liquid chambers can not be compressed; the pressure in both liquid chambers is even; the rigidity of the rubber spring is unchangeable. All of assumptions are the supplement between the model and the practice.On the foundation of the mathematic model that is set up in the front chapter, a Simulink model is set up in the end, and the performance with control and without control is simulated in Matlab. The result of the simulation indicates that the active engine mount can isolate the vibration that is transmitted by the engine to the vehicle chassis effectively. The transmitted force with control is less than 15% than that without control in four seconds and nearly zero in ten seconds. The performance is also simulated when the parameter of the rubber spring varies. The result indicates that the transmitted force with control is less than 5% than that without control in ten seconds and nearly zero in fifteen seconds. The capability of vibration isolation for the mount is slightly debased after the parameter of rubber spring varies. LMS algorithm works very well in the whole engine working frequency range. The result confirms the adaptive ability and stability of LMS algorithm.With the development of the science, people's requires to the performance of cars are not only the speed or other single one, but also all aspects of cars including the dynamic performance, the economic performance, easy-operating performance, etc. The electromagnetic hydraulic mount is proved of good capacity in vibration isolation. We believe that it can bring cars a new change and meet people's need for better comfort performance.