Working Mechanism And Key Technology Of Magneto-rheological Variable Inertia And Damping Torsional Damper

Torsional vibration is widely present in the power transmission system.It is the main source of vibration and noise of mechanical equipment such as vehicles,ships,and aircrafts.It has an important impact on the safety,comfort and even noise and stealth of the structure.The torsional vibration of the system is inevitable due to the characteristics of internal combustion engine cylinders such as deflagration and discontinuous work.If the motor is used as the power source,although the torsional vibration is improved,the torsional vibration caused by factors such as frequency conversion and load changes cannot be avoided.With the development of power plants in the direction of high power density,the requirements for the control of torsional vibration and noise of the power transmission system are also increasing.The use of torsional vibration absorbers is an effective method to suppress torsional vibration.The excitation source of torsional vibration is complex and changeable.Although the traditional passive frequency modulation and damping vibration reduction are simple,they only have good effects for specific working conditions and cannot realize adaptive adjustment under different working conditions.The torsional vibration of the power transmission system has a typical multi-order mode with different main harmonics,and the requirements for damping and inertia are different under different working conditions.For example,when starting,a small moment of inertia and large damping are conducive to fast starting and suppress excessive amplitude,while large moment of inertia and proper damping are beneficial to reduce speed fluctuations during normal operation.Obviously,passive adjustment cannot meet this demand.Although the active adjustment technology can meet the vibration damping requirements under different working conditions,it has a complex structure and high energy consumption.Therefore,variable inertia and damping adjustment based on semi-active technology is an effective method to solve torsional vibration.As a smart material,the magneto-rheological(MR)fluid can realize semi-active adjustment of the moment of inertia and damping,which provides a new idea for solving the torsional vibration of the power transmission system.For this reason,this article takes the power transmission system as the object,and studies the working principle of a position-sensitive variable gap MR damper.On this basis,a design method of a MR torsional vibration damper with variable inertia and damping is proposed.The validity of the principle and method is verified through theory and experiment.The main research contents of this paper are as follows:1)The working principle of the variable gap MR damper with position sensitivity is studied.The Bingham bi-plastic model is improved to accurately describe the rheological properties of MR fabrics.The MR fabrics of different density and thickness were tested and compared with the model.The calculation method of variable gap MR damper with position sensitivity is proposed.The formula for calculating the output damping force before and after yielding is deduced.The optimization design method of the damping gap is discussed,and the influence of the excitation magnetic field,the position gap function(the slope is constant,the slope is increasing and the slope is decreasing)and the movement speed on the output damping force are analyzed.It provides a theoretical basis for accurately regulating the position of the key piston element with variable inertia.2)Explore the design method of MR variable inertia and damping torsional shock absorber.Based on the working principle of the position-sensitive variable gap MR damper and the rheological mechanism of MR fabric,the structural integration scheme of variable inertia and inertial differential variable damping torsional vibration damper is analyzed.The calculation formulas for the inertia and damping force of the torsional shock absorber are deduced respectively.The influence of excitation current and rotation speed on the inertia and damping of the torsional shock absorber is analyzed.Aiming at the variable inertia and damping force of the torsion shock absorber,the key structural parameters of the torsion shock absorber are optimized.The arrangement and assembly process of the magnetic field generator of the MR variable inertia and damping torsional vibration damper are discussed.Through theoretical calculation and simulation,the variable moment of inertia and damping performance of the MR variable inertia variable damping torsion shock absorber are analyzed.3)The prototype of MR variable inertia and damping torsional shock absorber was processed.The working characteristics of variable inertia and variable damping of the prototype were tested.A control model describing the characteristics of the work has been established.The test method of MR variable inertia variable damping torsional shock absorber is proposed.Through quasi-static damping force test,rotating damping moment test and static/dynamic moment of inertia test,the influence of excitation current and speed on the output moment of inertia and damping force is studied.The error between the experimental results and theoretical calculations is compared and analyzed.A polynomial modeling method is used to describe the non-linear function relationship between the output moment of inertia and damping force of the torsional shock absorber and the input speed and current.4)The torsional vibration research platform was built to verify the open-loop control effect of the MR variable inertia and damping torsional vibration damper on the torsional vibration.Based on the servo motor and rapid control prototype,different control signals are input to simulate the system startup,operation and braking stages.The output speed characteristics of the system under different moments of inertia and damping matching and different working stages of the torsional shock absorber are studied.The control strategies of the moment of inertia and damping in different stages are given.The effectiveness of the MR variable inertia and damping torsional vibration damper in suppressing the torsional vibration of the power transmission system is verified.