Theoretical And Experimental Investigations On Dynamics Of Spur Planetary Gear Transmissions Based On Planet Phasing Theory

Planetary gear trains (PGT) yield several advantages, including high speed reduction,compactness, greater load sharing and higher torque to weight ratio, which are usedwidely in navigation, marine, automobiles and other applications. In some importanttransmission applications, the noise and vibration is a key concern in design. Theresearch work of this dissertation is a part of the Elastodynamic Analysis andDynamic Design of High-Speed Planetary Gear Transmissions of the NationalScience Foundation of China. The natural modes and the dynamic responses causedby the mesh frequency excitation are investigated in detail. The research works arelisted as follows:1. Based on the simplified purely torsional model of the single stage 2K-H spurPGT, the natural modes are studied, and the typical vibration modes and thephenomenon of vague vibration mode in the PGT are discovered by the inductiveapproach. For closely spaced eigenvalues, there are no distinct vibration modes. Bysolving the reduced-order eigenvalue problem of each type of vibration modes, aclosed form expression for natural modes of the PGT has been derived. From thepoint of view of the modal strain energy, the influence of loci veering on dynamiccharacteristics is studied and the criterions of the loci veering are derived.2. The theory of planet phasing (TPP) of the PGT is investigated. The relationsbetween the three types of vibration modes and the three forms of mesh excitation areclarified. The influence of planet gear tooth number on dynamic responses is analyzed.The TPP based on the purely torsional model of the PGT is established, and simulatedby a simulation. The phenomenon of basic parameters affecting the vibrationreduction by floating center parts is studied. For the vibrations whose fundamentalfrequencies equal to the mesh excitation, only when the center gear's tooth numbercan not be contained by the planet gear', can the vibration reduction method hasdistinct effectiveness.3. From the point of view of random analysis, the dynamic characteristics of thePGT are studied, and the statistics expressions of the three types of frequencies aregiven. The phenomenon of the statistics mutation caused by loci veering is analysed.The problem of resonance failures caused by mesh frequency excitation is quested.The expressions of the three resonance failures are given for the first time, and thedynamic reliability design of the PGT based on the resonance failure is presented.4. The prevailing parlance of using the prime teeth in high-speed PGT tosuppress vibration, which is widely cited in native mechanical design handbooks, isoppugned. Two typical work conditions are given for the first time. Based on the TPP,a new method for the selection of the basic parameters of the PGT is offered, and theparameter series of the PGT is redesigned.5. The systematic experimental work using single stage 2K-H spur PGT wascarried out to verify the lower order resonance, the TPP and the effectiveness of themethod based on the TPP for noise reduction is examined. The result of theoreticalanalysis of the TPP is consistent with the experiment result, but there are somedifferences between them, which is analysed in the dissertation. The effectiveness ofthe method for noise reduction based on the TPP is examined, which sustained thevalidity of the TPP to some degree.