Influence of Backlash on Load Sharing and Dynamic Load Characteristics of Twice Split Torque Transmission System
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Abstract
Introduction
Based on the characteristics of the helicopter main reduction gearbox, and combined with the advantages of face gear and cylindrical gear power dividing, a new configuration of helicopter main gearbox with twice split paths is proposed. A bending–torsional coupled dynamic model of the system is developed through the lumped parameter method, and the influence of stiffness, damping and backlash are considered.
Methods
The dynamic equation is solved by Runge–Kutta method, and the load sharing and the dynamic load coefficients are obtained, as well as their variation with the backlash.
Results
Results show that with the increase of the backlash, the load-sharing coefficient decreases, the dynamic load coefficient increases, but the other drive stages are almost unaffected. Compared with split torque stages and power confluence stages, the load sharing and dynamic load coefficient of power input stages are the most sensitive to the backlash of the power input stage, and the appropriate increase of the backlash can effectively improve the dynamic properties.
Conclusion
Therefore, in order to obtain better dynamic performance, it is necessary to allocate the backlash reasonably.
Keywords
Face gear Split torque Load sharing Dynamic load coefficientList of Symbols
- b
Backlash
- c
Meshing damping
- cDm, cifp, cijsjh
Torsional damping of the corresponding shaft
- e
Eccentric error
- fl(Yt)
Gap function
- Fifx, Fify, Fifz
Component forces of the meshing force of the face gear pairs
- Fijx, Fijy
Component force on the split shaft
- Finmf, Finpjs,FinBjh
Meshing forces of Zm and Zif, Zip and Zijs, ZB and Zijh
- Fipx, Fipy, Fipz
Component forces on duplicate shaft
- Fl
Meshing force
- Fmx, Fmz
Component force on the input shaft
- FBx, FBy
Component force on the output shaft
- Gl
Dynamic load coefficient
- Im, Iif, Iip, Iijs, Iijh, IB
Moment of inertia of Zm, Zif, Zip, Zijs, Zijh and ZB
- km
Average meshing stiffness
- k0
Variation amplitude of meshing stiffness
- KDm, Kifp, Kijsjh, KBo
Torsional stiffness of the input shaft, duplicate shaft, split shaft and output shaft
- Kl,
Meshing stiffness
- Kipx, Kipy, Kipz
Support stiffness of duplicate shaft
- Kinmf, Kinpjs, KinBjh
Time-varying meshing stiffness of Zif and Zm, Zip and Zijs, ZB and Zijh
- Kmx, Kmz
Support stiffness of input shaft
- mm, mif, mip, mijs, mijh, mB
Lumped mass of Zm, Zif, Zip, Zijs, Zijh and ZB
- Pl
Static load of gear pairs
- Ωimf, Ωijs, Ωijh
Load sharing coefficient
- ribp, ribjs, ribjh, rbB
Base circle radius of Zip, Zijs, Zijh and ZB
- rif
Equivalent meshing radius of face gear
- rifp, rijsjh
Equivalent radius of duplicate shaft and split shaft
- rm
Radius of pitch circle of Zm
- rDm, rBo
Equivalent radius of the input shaft and output shaft
- TD, To
Input torque and the load
- Xinp, Yinp, Zinp
Displacement of duplicate shaft along the coordinate direction
- Xij, Yij
Transverse displacement of split shaft
- Xnm, Znm
Transverse and axial displacement of input shaft
- XB, YB
Transverse displacement of output shaft
- Zif, Zijh
Face gear, the pinion of power confluence stage
- Zip, Zijs
Driving and driven gear of split torque stage
- φD, φm, φB, φo
Torsional displacement of input, Zm, ZB and output
- φif, φip, φijs, φijh
Torsional displacement of gear Zif, Zip, Zijs and Zijh
- θip, θij, θiB, θB
Installation angle
- i
R, L
- j
1, 2
- l
inmf, inpjs and inBjh
Notes
Acknowledgements
The work is fully supported by National Natural Science Foundation of PRC (Grant No. 51475226).
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