On our country's rubber parts suspension device structural improvement has significance for reference and guidance. Generally speaking, the car has mainly two aspects of vibration, one is caused by road roughness, two is the engine itself generated in the working process of the unbalanced force and torque. With the development of modern highway and raising the level of various suspension optimization, dynamic assembly has gradually become the main vehicle vibration source effect. On the other hand, the modern automobile is toward miniaturization, lightweight and high comfort goal development. The power assembly suspension device to improve vehicle comfort and to reduce interior noise plays an important role in. Domestic and foreign scholars on the various power assembly suspension device to carry out a great deal of research, as early as 1920rubber element is used to connect the powertrain and chassis, in 1930 after the rubber suspension device used for isolating engine vibration transmitted to the frame, after decades of research, suspension components have been greatly developed, produced fluid resistance hydraulic suspension, semi-active control and active control suspension device. At present, as the cost of manufacturing, structure and manufacturing process and other aspects, in foreign countries, in heavy duty truck hydraulic pressure suspension device almost has not been applied, often using the traditional rubber materials as vibration isolation elements. In our country most of buses and trucks are using rubber suspension device. Because the traditional rubber suspension device has the rigidity big, insufficient damping and high frequency dynamic hardening shortcomings, can not meet the requirements of power assembly. But the rubber suspension device for isolating vibration in all directions to design appropriate stiffness characteristics, it has the advantages of small volume, low price, almost no maintenance, bonded together by rubber suspension device can have better performance for longer life. Therefore, the application of nonlinear stiffness and damping characteristics to improve the passive rubber suspension device performance, application of high damping materials and has an amplitude is determined the degree of Yu Gang and the damping material is very valuable. Due to the large damping rubber material performance instability, application is very difficult, this paper adopts natural rubber production rubber suspension device as the object, through the simple principle of transformation, which has good nonlinear characteristic, obtain the ideal dynamic characteristics. This paper established a modified rubber suspension mechanical model, through theoretical analysis and simulation, it is proved that the better dynamic characteristics. Traditional rubber suspension device and ideal suspension device of automobile powertrain is compared through suspension system installed in the vehicle frame or on the vehicle, suspension system under power assembly quality, under various disturbances, such as braking, acceleration, cornering situations, suspension system can effectively limit the power assembly of the maximum displacement, in order to avoid collision with adjacent parts.
At the same time, it should have good effect of vibration isolation, as far as possible to reduce powertrain and vehicle frame or body between the two-way transmission of vibration. The vibration analysis of knowledge : to make the power assembly suspension device in low frequency and large amplitude vibration, effectively limits the maximum displacement engine powertrain, suspension device should have a larger dynamic rigidity and large damping. On the other hand, in order to reduce engine power assembly in high frequency and small amplitude vibration to the frame or body of the force transfer rate, requirement suspension device with small stiffness and damping. Therefore, through the research to obtain the desired suspension device characteristics, and compares it with the traditional rubber suspension were compared, as shown.
By the known: the traditional rubber suspension damping almost does not vary with frequency and amplitude changes, as a constant, and stiffness characteristics and ideal suspension device to draw further apart, low frequency, low stiffness, high frequency, stiffness, and basically linear change; and substantial value of dynamic stiffness of small a small value, dynamic stiffness of traditional rubber suspension device characteristics and ideal suspension characteristics contrast large. Therefore, the traditional rubber suspension device to meet the power train suspension device of high frequency and small amplitude and low frequency and large amplitude of the request, must carry on the reform to the structure with nonlinear characteristics, better meet the needs of power train suspension system requirements. Traditional rubber suspension damping block structure usually takes the form of compression, shear and complex of 3, as shown in the diagram.
The traditional rubber parts suspension device structural form of compression type rubber damping block structure was improved as shown. Rubber is a kind of high molecular material, is a kind of nonlinear material, rubber elastic hysteresis, whereby the load after a certain period of time will produce the final deformation. Similarly, after unloading, also take some time to recover. The improved rubber suspension device each comprise 5ranging from the level of the rubber block, a metal frame is spaced between them, each other almost not influence each other. According to the different orientation can be divided into those of low and high side edge of high school low type. In the different working conditions, they have different working state. When the power assembly work at low frequency and large amplitude vibration, the two forms of rubber suspension of 5 rubber piece of work at the same time, the suspension stiffness increased significantly, while the damping is increased accordingly, to meet the needs of the powertrain in low frequency and large amplitude of suspension stiffness, large damping requirements. When the power assembly at high frequency and small amplitude vibration condition, two kinds of rubber suspension device work is different. For a shows in the high side low type rubber suspension device, only the highest improved rubber suspension device of a block in working condition, and this has a stiffness and damping is the smallest. For the B side of high school low type, for a maximum of 2rubber block is in working state, therefore they are with low stiffness and damping. Two forms of rubber suspension device can effectively improve the traditional rubber suspension device in high frequency and small amplitude of the working condition, and better meet the needs of power train rubber suspension device of high frequency and small amplitude when Xiao Gang small damping requirements. Of course, in order to make the rubber suspension and powertrain matching, it is necessary to set a reasonable5 rubber block height difference. Because the traditional rubber suspension device commonly used a shows mechanical model to study < 5>. Therefore, a high side low type rubber suspension device can be built as specified in subclause B mechanical model.
K suspension stiffness C suspension damping K1rubber block1 of the stiffness of the K2 rubber block 2,5 of the stiffness of the K3 rubber block 3,4 of the stiffness of the rubber block 1of the C2C1damping rubber block 2,5 of the damping rubber block 34C3, damping rubber suspension mechanics model the suspension device is designed to be symmetrical, so on the left rubber block was simplified think they have the same stiffness and damping. The rubber itself quality compared to the powertrain quality of small, neglected the quality of rubber block. If the amplitude increases, the amplitude attenuation and collision after consumption, with large amplitude vibration corresponding equation. On solving various amplitude can be obtained for the time response of a process, and get the steady-state response of the amplitude and phase difference. Exciting force for sinusoidal excitation. Improved rubber suspension dynamic characteristic analysis of small amplitude vibration dynamic characteristics in the established simulation model, amplitude frequency response, with the help of transfer function program got under small amplitude frequency response as specified in subclause a. Map can be seen, in the amplitude is less than, the main work area is centered in the frequency range, especially in the high frequency region in time, amplitude is less than, with very good vibration damping effect, can effectively improve the dynamic characteristics of power assembly. In the resonance zone amplitude increases, greater than, causes the displacement is too large, the rubber block to play a role in increasing the suspension stiffness and damping, the amplitude drops. That is to say the system in vibration, amplitude is greater than in the case of almost never occur, and will be replaced by. Because the rubber block intervention, so that the vibration natural frequency of the system occurs transiently increases, amplitude can be rapidly reduced, in addition, damping increased also makes the amplitude decreases rapidly. Compared with the traditional rubber suspension device of the amplitude frequency characteristics ( such as C below) contrast, can more clearly see the effect of. Under small amplitude frequency response according to the above results, the small amplitude vibration, the improved rubber suspension device has ideal amplitude-frequency characteristics, especially in the high frequency region.
Large amplitude vibration of dynamic characteristic of power assembly work in the start, idle, acceleration, deceleration, brake and turn and other conditions, often causing engine greatly. So it is necessary to study the dynamic characteristics of large amplitude at. Usually in these cases, the excitation frequency is low, so only on the frequency of the working condition. At this time, a rubber block is in working condition, suspension system with large stiffness and damping can effectively limit the powertrain of the maximum displacement of the amplitude frequency characteristics, as shown in. Large amplitude vibration of low frequency, the amplitude frequency characteristics of conclusion of traditional rubber suspension device characteristics and ideal suspension were compared, and an improved design is put forward. In the improved suspension device structural corresponding mechanical model is established, and then obtain the mathematical model of the system, program of this model were simulated and calculated, the results show that the new structure of the rubber suspension device can obtain the ideal dynamic characteristics ( the only discussed the amplitude-frequency characteristic ), to our country rubber suspension improvement of device has a good reference and guidance. But it should be pointed out that this improved structure can not thoroughly solve the high frequency dynamic stiffness of rubber suspension device, can effectively reduce the dynamic problem of hardening. In addition to rational design of suspension preload, for this type of suspension and dynamic characteristics have a great effect.
