The multi-power face gear split flow system is a new type of transmission system, which has the advantages of stable and reliable transmission and strong carrying capacity. And it has great potential in the application of helicopter transmission systems. In this paper, the multi-power face gear split flow system was taken as the research object. Based on the lumped parameter method and Newton’s second law, the translational-torsional dynamic model of the system was established considering the translational vibration and the torsional vibration of the gears, and the meshing force curves and load-sharing coefficient curves were drawn. At the same time, the factors affecting the load-sharing characteristics of the transmission system were studied. The impacts of manufacturing errors, assembly errors, manufacturing error phases, assembly error phases, meshing damping, support stiffness, and the input power on the load-sharing coefficients were analyzed. The research shows that the errors and error phases of spur gears have small impacts on the load-sharing coefficients, while the support stiffness of spur gears has a great impact on the load-sharing coefficients. The errors and error phases of face gears have small impacts on the load-sharing coefficients, while the support stiffness of spur gears has a great impact on the load-sharing coefficients. The load-sharing coefficients increase constantly with the increase in the meshing damping between face gears and spur gears, whereas the load-sharing coefficients decrease constantly with the increase in the input power.

No abstract

In the field of mechanical engineering, involute helical gears are widely used. Compared with the involute spur gear, helical gears have a high bearing strength, more smooth transmission, less impact and less noise. The internal gear pairs have the features of large transmission ratio, low vibration, low noise and low wear and hence are widely used in planetary gear transmission systems. In order to meet the requirements of high strength, high speed of the modern gear transmission systems, a new type of asymmetric involute internal helical gears is designed based on conventional involute gears. This paper discusses the gear shaper cutter modeling for machining this new gear, analyzes the formation principle of asymmetric tooth profile and establishes a three-dimensional modeling by SolidWorks. Through MATLAB simulation, pressure angle, tooth number, coefficient of displacement and contact ratio of conventional and asymmetric gear are compared and analyzed. Using ANSYS, two types of gears are compared on strength in order to demonstrate superiority of asymmetric tooth and further study about the asymmetric internal helical gears.

No abstract

No abstract

No abstract

Face gear transmission is a kind of space-meshing mechanism that is mainly used in the field of aviation. Compared with traditional transmission, it has the advantages of stability, reliability, low noise, and strong carrying capacity. However, owing to its complex tooth surface, there are no means to accurately model the face gear. Likewise, research based on the geometry is difficult. Therefore, the tooth surface equation of the face gear is derived in this article based on the meshing theory. Based on the equations, the point cloud of the face gear tooth surface is calculated, the complex tooth surface is generated, and the face gear is accurately modeled. Moreover, taking tooth surface friction excitation into consideration, a multi-degree-of-freedom nonlinear dynamic model of face gear transmission system is established, using the adaptive variable step length Runge–Kutta method. As shown in the results, the bifurcation diagram, phase diagram, time history diagram, and Poincaré section diagram are combined to analyze the influence of tooth surface friction and meshing frequency on the dynamic characteristics of the system.

This paper studies the multiple-split load sharing mechanism of gears in two-stage external meshing planetary transmission system of aeroengine. According to the eccentric error, gear tooth thickness error, pitch error, installation error, and bearing manufacturing error, we performed the meshing error analysis of equivalent angles, respectively, and we also considered the floating meshing error caused by the variation of the meshing backlash, which is from the floating of all gears at the same time. Finally, we obtained the comprehensive angle meshing error of the two-stage meshing line, established a refined mathematical computational model of 2-stage external 3-split loading sharing coefficient in consideration of displacement compatibility, got the regular curves of the load sharing coefficient and load sharing characteristic curve of full floating multiple-split and multiple-stage system, and took the variation law of the floating track and the floating quantity of the center wheel. These provide a scientific theory to determine the load sharing coefficient, reasonable load distribution, and control tolerances in aviation design and manufacturing. PrefaceTwo-stage external meshing planetary transmission system is widely used in aviation and special precision transmission field. The T53-L-11 turbo-axis aircraft engine produced by Lycoming (US Company) used two-stage external meshing planetary transmission system as its reducer. Located in the engine head and installed in the intake box, reducer transports the motivation from free turbine shaft to the second sun gear after decreasing speed and increasing torque. Two-stage star gear transmission has multiple duplicate gears with fixedaxes to share the load, its star gears do not revolve, and its characteristics are power split, high transmission power, and only one-side load bearing, and so on. Two-stage star gear transmission uses two-stage star gears, without the ring gear, directly output by two external gears, so that it overcomes the alternating load of planet gear in traditional planetary gear transmission, the difficulty in processing of ring gear, the centrifugal force caused by the rotation of carrier, and intermittent lubrication of planet gear. The system strength, stiffness, and working life and reliability of transmission system have greatly improved by using two-stage fixed-axis external meshing gears. In this paper, a precise load sharing characteristic analysis model is established for all gears with angular displacement compatibility, including bearing manufacturing errors, gear manufacturing errors (eccentricity error, tooth thickness error, and pitch error), installation error, and the meshing error caused by the variation of the meshing backlash resulting from simultaneous floating of all the gears. Research results can be used for aircraft engine and other precision special transmission systems in load sharing coefficients determination, vibration noise reduction, structure optimization, and error precision control. This paper provides sci...