Research On Design Method And Error Analysis Of A Spherical Gas-Floated And Driven Gyroscope

Gas-lubricated devices have many advantages, such as high rotation rate, high accuracy, low power dissipation and long life. These merits suit for needs of inertia devices, which make gas bearing technique widely studied and applied in gyroscopes. To some gyros having special structure, for example spherical gas-floated gyro, research on gas-lubricated theory is not sufficient, and its design theories is not sufficient, which induce unsuring load performances and high disturbing torque, resulting in unexpected excursion accuracy. For these reasons, aiming at spherical gas-floated gyros, carrying out research on gas-lubricatated performances could perfect its design, conquere harmful disturbing torque, and improve its excursion accuracy, having practical effect in engineering application.The thesis introduces a gas reaction-propelled spherical gas-floated gyro, and presents its design demends, working principle and key techniques need to be solved. Manufacturing and assembling errors, together with change of working conditions is analysed, considering the gyros'structure and processing, and their influences to the gyros'performances are discussed. After that, causes of excursion are listed and methods to improve excursion accuracy are proposed.To analyse gas-lubricated performances of the gas-floated and driven gyroscope accurately, the foremost problem is the numerical solution of gas-lubricated equation. Aimed at spherical gas-floated gyros, the thesis introduces Reynolds' equation expressed in spherical coordinate system. In order to simplify analysis, parameter thansform is used to the equation, changing the equation into the standard type expressed in Cartesian co-ordinates. To simplify equation's boundary conditions in externally pressurized gas lubrication, flux of bearing restrictors is merging into the equation as a new term. The Galerkin's weighted residual method is adopted to the reconstructived equation, to reduce the second-order partial differential equation to one-order, which releases the requirement of continuity degree of the interpolation function, after that, triangle cell is used in finite element method to discretize computing field, and FEM model solving press equations is proposed.Comparing with ordinary bearings, gas bearings have lower carrying capacity, while reasonable load performances is the basis of gyros, so the accurate numerical value of load performances is important in design procedure. The thesis describes the bearing gas-film as function of coordinate and eccentricity, and proposes computing means of carrying capacity and stiffiness. On this basis, load performances of spherical bearing when the rotor is resting are presented. Influences of structure and environment parameters are analysed, and comparison between orifices or slot-entry throttling bearings is presented. While the gyros'rotor is working at high rotation rate, both aerostatic effect and aerodynamics effect are existed, the thesis analyses influences of rotation rate to load performances, and parameters mainly affect aerodynamics effect, together with their influence rules. Considering manufacturing and assembling errors, also change of working conditions, the thesis analyses their influences on carrying capacities to find sensitive errors, for guiding precision design and reducing cost.Disturbing torque caused by gas is one of main reasons influencing gas-floated gyros excursion accuracy, while its theoretics analysis, mathematics model and couputing means all absented at present. The thesis establishs the mathematics model of disturbing torque caused by gas in spherical gas-floated bearings, and achieves its numerical value. To reduce disturbing torque effectly, considing structure and processing of the gyros, manufacturing, assembling errors and change of working conditions, and their influences on gas disturbing torque are analysed.Usually, electromagnetism driving device is used in gas-floated gyros, while it concomit with electromagnetic disturbing torques and complex structure. The thesis proposes a gas reaction-propelled method suit for minitype gas-floated rotors, which can avoid electromagnetic disturbing torques, and simplify the gyros'structure. Driving principle, implemental means are discussed. Mathemethetic model of driving characteristic is established, and influence of parameters and errors to stating characteristic is analysed.On the basis of theoretical analysis, the main manufacturing and assembling errors of prototype are tested, comparation are conducted about load capacity, and disturbing torque. Results of experiments verify the validity of models and calculation results in this thesis.