1、utomotiwe Engineers, IRC. TWO PENNSYLVANIA PLAZA, NEW YORK, N.Y. 10001 .- . - - - - - .- _ TURBINE DRIVE SHAFT CONNECTION Issued 3-15-70 Revised 1. 2. 2.1 2.2 SCOPE This ARP applies to turbine engines that are to be used in helicopters. It provides the engine de- signer guide lines in achieving a sa
2、tisfactory turbine engine drive shaft connection. RECOMMENDATIONS The engine drive shaft connection (Figure 1) shall be either a flange drive with pilot, or an involute spline, If an involute spline, an internal spline on the engine side is preferred. Involute splines may be either the locked type o
3、r the floating type as follows: (a) Locked type: aligned and secured to the mating spline in the helicoper transmission. These shall have a pilot and an internal thread by which they shall be (b) Floating tvp e: These are not fixed axially and have a very limited capability for accommodating radial
4、and angular misalignments. Normally, they are able to accommodate angular misalignments of up to 20 minutes. Floating splines shall be lubricated, Lubrication by.the engine lubricating system is preferred. Regard- less of how lubrication is accomplished, however, it shall be such that no lubricant n
5、eed be added between engine overhaul periods. Where weight, envelope and cost penalties are not severe, it is desirable for the spline on the engini side to be designed such that it can be used as either a locked spline or a floating spline as required. The allowable externally imposed loads on the
6、engine drive shaft shall be specified in the engine model specification. This shall include both steady state and transients in the form of thrust and transverse moment loads. The following guide lines are recommended in establishing engine con- nection requirements : 2.2.1 2.2.2 For the purpose of
7、life calculations and/or test demonstration, the transient loads can be con- sidered to have a duration of 10 seconds maximum and accumulaed exposure time equal to 1% of the total operating time. If a floating spline connection is part of the engine shafting, the transient thrust and transverse mome
8、nt loads shall be calculated with the following formulas using a recommended coefficient of friction between O. 10 and O. 15. The recommended coefficients of friction include the effect of spline pressure angles of 30 deg or less. These friction coefficients require a spline length/diameter ratio of
9、 O. 3 or less for the highly loaded splines associated with light weight design. A highly loaded spline with a length/ diameter ratio greater than O. 3 may result in a coefficient of friction higher than O. 15. 1970 by Society of Automotive Engineers, In ,- -2 - II FA = q- Mg =fT Where: = Thrust or
10、axial force, pounds FA MS = Shaft moment, transverse, pound-inches T = Engine output torque, pound-inches r = Fitch radius of floating spline, inches f = Coefficient of friction 2.2.8 GQnerally, the helicopter designer will use misalignment couplings (Figure 1) as part of the helicopter shcfting. Mi
11、salignment couplings are used because the amoiint of misalignment in operational heli- copter drive shafts frequently exceed the amount that the engine connection can tolerate. Observe the following where misalignment aouplings are used: (a) For stability, a floating spline connection shall not be u
12、sed in conjunction with a misalignment coupling. Either a locked spline, or a flange connection, per Para. 2.1 shall be used. (b) A type of misalignment coupling in common use is the gear coupling. A typical gear coupling is an involute spline coupling with barreled teeth and a length to diameter ra
13、tio of less than O. 10. For G proper installation, the engine connection must be designed to withstand the axial thrust and transverse moment loads imposed by gear couplings. The equations below establish guide- lines for axial thrust (F ) and transverse moments pis). Limited data from helicopters w
14、fth well de i ed gear couplings shows the range of pitch radius (r) to be between O. 07T O. 10Tl9?where T is the engine output torque. The value for the coefficient of friction (f), of O. 10, was established by test with well designed gear couplings and includes the effect of a pressure angle of ZOO
15、. 1/3 to A Ms = fT = O. 10 T 2.3 Engines may be designed or direct mounting to a power absorbing device. in this case the mounting pro- visions (such 88 a stationary pilot and perpendicular mounting face) shall have sufficient accuracy with re- spot to the drive shaft so that the engine can be attac
16、hed without need for adjustment. PREPARED BY SAE COMMITTEE 5-12, HELICOPTER POWERPLANT SA ARP*72L 90 8357340 0023023 5 / -3- I 421 - TRANSMISSION OUTPUT SHAFT /- MISALIGNMENT COUPLING (Reference Para. 2.2.3) /- ENGINE CONNECTION (Reference Para. 2.1) TRANSMISSION GINE OUTPUT SHAFT 1-TRANSMISSION INPUT SHAFT TURBINE ENGINE-HELICOPTER TRANSMISSION INTERCONNECTION SCHEMATIC FIGURE 1
