Couplings and Alignment
Coup1ings in most turbomachines attach the driver to the driven piece of machinery. High-performance f1exib1e coup1ings used in turbomachines must perform three major functions: (1) efficient1y transmit mechanica1power direct1y from one shaft to another with constant ve1ocity,(2) com-pensate for misa1ignment without inducing high stress and with minimumpower1oss,and (3) a11ow for axia1 movement ofeither shaft without creating excessive thrust on the other.
There are three basic types of f1exib1e coup1ings that satisfy these require-ments. The first type is the mechanica1-joint coup1ing. In thiscoup1ing, f1exibi1ity is accomp1ished by a s1iding and ro11ing action. Mechanica1-jointcoup1ings inc1ude gear tooth coup1ings,chain and sprocket coup1ings, and s1ider or O1dham coup1ings.
The second type is the resi1ient-materia1 coup1ing. In resi1ient-materia1 coup1ings f1exibi1ity is a function of f1exing of materia1. Resi1ient-materia1coup1ings inc1ude those that use e1astomer in compression (pin andbushing,b1ock,spider,and e1astomer-annu1us,meta1-insert types); e1astomer in shear(sandwichtype,tire type); stee1 springs (radia1 1eaf,periphera1 coi1 types); and stee1-disc and diaphragm coup1ings.
The third type is the combined mechanica1 and materia1 coup1ingswhere f1exibi1ity is provided by s1iding,or ro11ing and f1exing. Combinationcoup1ings inc1ude continuous and interrupted meta11ic-spring grid coup1ings,nonmeta11ic gear coup1ings,nonmeta11ic chain coup1ings,and s1ider coup-1ings that have nonmeta11ic s1iding e1ements.
In choosing acoup1ing,the 1oading and speed must be known. Figure 18-1shows the re1ation between coup1ingtype,periphera1 ve1ocity coup1ingsize, and speed. The 1oadings in these high-performance f1exib1e coup1ings are as fo11ows:
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1. Centrifugal force.Varies in importance,depending on the system speed.
2. Steady transmitted torque. Smooth nonf1uctuating torque in e1ectricmotors,turbines,and a variety of smooth torque-absorbing 1oad (driven) machines. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址:燃气涡轮工程手册 Gas Turbine Engineering Handbook 3(23)