The Graph Library Based Rapid Topology And Parameter Synthesis Of Multi-Speed Bulldozer Transmission

As a kind of device that transmits power from engine to wheels,transmission can make vehicle adapt to different work conditions,and improve its mobility and controllability.As a kind of automatic transmission,planetary gear transmission has been widely applied in engineering vehicles including bulldozers,which has effectively improve the work efficiency and reduce the burden of drivers.Due to the complex working conditions of bulldozers,frequent shifting of gears and large output torque,high requirements are put forward for design.The existing bulldozer planetary transmission schemes are few,and the number of potential schemes is huge,which cause the difficulty of design.Based on the working conditions and structural requirements of bulldozer transmission,the research on the rapid topology and parameter synthesis of multi-speed bulldozer planetary transmission is proposed in this paper.In this paper,the constraints of the number of components of planetary transmission topology with multiple degrees of freedom(DOF)are established.A hybrid topology with its transformation model are proposed for the parallel-axis planetary transmission.By establishing the diagraph isomorphic model,the isomorphism determination of ordinary planetary transmission and parallel-axis planetary transmission is solved.The concept of Fundamental Geared Entity(FGE)is introduced,and the speed ratio of mechanism is derived by FGE composition method.This paper concludes the special cases of multi-FGE composition,proposes the extension formulas of composition,and therefore expands the scope of application of FGE composition.Based on the vertex merging method,the speed ratio calculation of planetary transmission with multiple DOFs is transformed into an equivalent problem with single DOF.A rapid synthesis method of multi-speed schemes based on graph library is proposed in this paper.By using diagraph isomorphic model,enumeration and filtering of non-isomorphic FGE graphs are carried out.And a graph library is established by calculating data such as speed ratio expressions in advance.Based on isomorphism test,vertex matching and corresponding speed ratios conversion between the scheme to be solved and the isomorphic scheme in graph library are realized,then a large number of speed ratios can be calculated rapidly.The efficiency calculation is analyzed to realize the prediction of schemes with low efficiencies and the prediction of speed ratio ranges.The third type of planar models based on planarity test are established to detect the geometric interference of the scheme,thus eliminating a large number of invalid schemes.The detailed parameter synthesis and optimization of planetary transmission scheme are carried out.The constraints and optimization equations of gear parameters synthesis of planetary transmission are summarized to achieve the goal of balanced maximum sliding rate and minimum mechanism volume,and the comprehensive optimization of scheme parameters is realized.Based on grid lattice and depth-first search,the connection path of topology scheme sketch is generated.By identifying and adjusting interference patterns and adding component sketches from component library,the complete sketches of planetary transmissions can be automatically drawn.The synthesis example of multi-speed bulldozer transmission is implemented,and many valid schemes are obtained,which proves the efficacy and efficiency of the synthesis method.