Document
www.nasa.gov Engineer Research Mechanical Robert F. Handschuh Engineer David G. Lewicki Research Mechanical Brook Park, Ohio, 44135 NASA, John H. Glenn Research Center
Status of Design and Testing at NASA GRC
Mark A. Stevens Mechanical Engineer
Concepts for Multi-Speed Rotorcraft Drive System -
Presented at the AHS 71st Annual Forum, Virginia Beach, Virginia, May 5–7, 2015. This is a work of the U.S. Government and is not subject to copyright protection in the U.S.
National Aeronautics and Space Administration www.nasa.gov .
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Objective
based on a dual-input planetary differential.
third concept multi-speed drives Highlight some positive/negative aspects and future development areas. Variable-speed gear drive Overview the Status of Three Drive Designs from an earlier concept study: 1. Design/testing of two 2. Update to the design of National Aeronautics and Space Administration www.nasa.gov is required for: varying rotor speeds 50%.
Background
variable rotor speed
– Reduction in noise – Increased performance – Enhanced capabilities (speed - capacity - range) Advances are contingent upon Present Limitations ~15% (via engine control).
increased efficiency, power, and enhanced capabilities
Future advances in rotorcraft propulsion systems require Studies show that
National Aeronautics and Space Administration www.nasa.gov Gearbox Tilt-Axis Gearbox Gas Turbine Engines Variable/Multi-Speed Combiner Gearbox Reduction Gearbox Gearbox Forward Flight Ratio 243.6 : 1 To Mid-Wing
V/M-S Gearbox Application
Hover Ratio 131.4 : 1
Future Rotorcraft Propulsion System Configuration
National Aeronautics and Space Administration www.nasa.gov requirement dropped due to complexity and budget requirement dropped due to scope and budget not an original requirement a b c 40C 104F 23.0 cSt 100C 212F 4.90-5.40 cSt -54C -65F pour point
Test Article Design Requirements
Provide high-speed positive drive element Light-weight rotating components (flight like) Housing design (modular, possibility of windage shrouds) Inline configuration (input-output shafts) Input Speed 15,000 rpm Output Speeds 15,000 rpm (hover), 7,500 rpm (cruise) Employ straight spur gear geometry (budget consideration) Drive should fail safe to the high-speed (hover) mode Lubricant: DOD-PRF-85734A, synthetic ester-based oil – – – 250 HP nominal (200 HP facility capacity) _______ a b c • • • • • • • • • • National Aeronautics and Space Administration Shaft www.nasa.gov Output Hydraulic Feed-Through Aft Bearing Sprag Main Clutch Disengaged 2:1 Reduction Drive (Cruise) Clutch (Main) 2x Clutch Modules Low-Speed Shaft
Modules: Gear & Clutch
Gear Train Forward Bearing 2x Gear Modules Main Clutch Engaged 1:1 Direct Drive (Vertical Flight) Input Shaft National Aeronautics and Space Administration www.nasa.gov Floating Fixity - Offset Cluster Gear Fixity - Main Rotating Ass’y Rotating Feed- Through Support Aft Brg Support
Baseplate/Supports/Housing
Rails Intermediate Brg Support National Aeronautics and Space Administration Fwd Brg Support www.nasa.gov
Two-Speed Drive Test Configurations
National Aeronautics and Space Administration Configuration 1: OCG / Dry-Clutch (Tested) Configuration 2: DSI / Dry-Clutch (Tested) Configuration 3: OCG / Wet-Clutch (In assembly) www.nasa.gov 2:1 1:1 Ring Gear Mesh 2 Oil Jets Sun Gear (OCG) Cluster Gear Ring Gear Sun Gear
Gear Module 1: (OCG) - Offset-Compound Gear
Mesh 1 Oil Jets Axis Offset National Aeronautics and Space Administration www.nasa.gov C/L OCG Offset Shaft 1 Support OCG Cluster Ass’y Supports OCG Cluster
Balancing the OCG Cluster Assembly
Shaft 1 Support Input Shaft 1 National Aeronautics and Space Administration System Drive Belt www.nasa.gov 2:1 1:1 Carrier (Fixed) Input Shaft Ring Gear Idler Gear
Gear Module 2: (DSI) - Dual Star-Idler Planetary
Sun Gear Star Gear National Aeronautics and Space Administration Ass’y Carrier www.nasa.gov Oil-In Plane Pass- Thru Brg Jet Assembly Planet Gear 3-Plate Carrier Spacer Sleeve Jets Mesh Oil In (Typ) Brg Jet Idler CW Out
DSI Planetary Gear Design
Load CCW Load CW Bearing Loads In CW CCW Out In CCW Bearing Loads vs.
Rotational Direction Sun National Aeronautics and Space Administration Ring Star www.nasa.gov Rpm__ 15,000 10,135 10,135 7,481 Rpm__ 15,000 39,474 37,500 7,426 teeth teeth N 25 37 31 42 N 50 19 20 101 Pitch Dia (inch) 2.865 4.240 3.875 5.250 Pitch Dia (inch) 4.1667 1.5833 1.6667 8.4167 Pitch 8.727 8.727 8.0 8.0 Pitch 12 12 12 12
Gear Parameters - OCG vs. DSI
OCG Gear Train Material: 9310, Backlash: 0.006-0.011 inch, Width: 0.375 inch, Contact Angle 20º Gear Input 2 3 Ring DSI Gear Train Material: 9310, Backlash: 0.010-0.015 inch, Width: 0.600 inch, Contact Angle 20º Gear Sun Star Idler Ring Observations: DSI planet gears spin at 4x the speed of the OCG cluster gear.
National Aeronautics and Space Administration www.nasa.gov dN factor 450,000 592,110 562,500 371,300 dN factor 450,000 1,114,850 1,114,850 374,050 brg brg d 30 15 15 50 d 30 110 110 50 brg brg D 62 35 35 90 D 62 140 140 90 Size 206 202 202 210 Size 206 1822 1822 210 Rpm 15,000 39,474 37,500 7,426 Rpm 15,000 10,135 10,135 7,481
Bearing Parameters - OCG vs. DSI
DSI Bearing Parameters. =========================================== Site Sun Star Idler Ring ________________________________________________ (Bearing diameters in millimeters) OCG Bearing Parameters. =========================================== Site Input 2 3 Ring ________________________________________________ Observations: Bearing dN are higher for OCG despite high speeds of the DSI planet bearings.
National Aeronautics and Space Administration www.nasa.gov Intermediate Speed (rpm) 30,000 37,500 +25% speed increase due to reduced diameter planets 10,000
Observations – Gear Trains
High planet gear speed is an inherent aspect of a single stage planetary gear train with a 2:1 output since the ratio is defined by the ratio of pitch diameters of the ring and sun gears. For a basic 2:1 Planetary: Ø5.0 sun & Ø10.0 ring yields the following intermediate gear speeds for an input speed of 15,000 rpm Gear Train Basic Planetary DSI (idler addition) OCG The OCG is simpler to lubricate due to reduced number of gear meshes and bearings.
National Aeronautics and Space Administration www.nasa.gov * Output Shaft * Rotating Feed-Through Sprag Intermediate Shaft Low-Speed Shaft * Release Bearing Ass’y
Clutch Module: (DC) DRY-CLUTCH
Dry-Clutch 1:1 Clutch Hub * Unique hardware necessary to meet the inline design requirement 2:1 National Aeronautics and Space Administration www.nasa.gov Signal Hydraulic Shaft Output Intermediate Output Shaft Bearing Ass’y) Piston (Release
Dry-Clutch Design
Clutch Springs Pre-Load 1:1 Input National Aeronautics and Space Administration Clutch Hub Flange www.nasa.gov Output Shaft Rotating Feed-Through Sprag Release Piston Drive Springs
Clutch Module: (WC) Wet-Clutch
Low-Speed Shaft 1:1 Drive Plates 2:1 National Aeronautics and Space Administration www.nasa.gov Signal Hydraulic Shaft Output Drive Springs Orifice Bleed
Wet-Clutch Design
Release Piston Polygon Drive Drive Plates 1:1 National Aeronautics and Space Administration Input Flange www.nasa.gov C B A Lube/OiI Inlets Sprag Lube Ports Shaft Low-Speed Piston Release Drains
(Wet-Clutch)
Orifice (Bleed) Lube Jets Drive Plate Drains
Output Shaft Hydraulic / Lubrication Passages
Bearing Lube Jets National Aeronautics and Space Administration www.nasa.gov (Wet-Clutch) (Dry-Clutch) Closed-Loop Load Path Closed-Loop Load Path “D” “B”
Clutch Release Closed-Loop Load Path
“C” National Aeronautics and Space Administration “A” www.nasa.gov • 15,000 rpm • Ring Seals – DuPont Vespel • Significant drag A, B, C Lube Inlets Main Housing Aft Wall O-Rings
Rotating Hydraulic/Lubricant Feed-Through
Ring Seals Rotating Feed-Through National Aeronautics and Space Administration A, B, C Lube Oil www.nasa.gov 16-element 4-lube inlets 4-drive pins Addition of aft-sprag bearing forming straddle duplex bearing support Sprag • • Races • Revisions • Sprag Sprag A A Straddle Support Duplex Bearings Low-Speed Shaft
Sprag (Overrunning Clutch)
Races Lube Inlet (Shaft) Lube Drain (Hub) Hub A-A Sprag National Aeronautics and Space Administration www.nasa.gov
Variable-Speed Drive
Future Design (Concept 3)
Dual-Input Planetary Differential
Second Input Is Not Within Current Scope
– Sun Gear - Input – Carrier - Control (Second Input) – Ring Gear – Output Concept Variable-Speed Drive leveraged from the DSI Planetary Gear Train & Lubrication Design Direct Point Bearing and Gear Lubrication
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National Aeronautics and Space Administration Output www.nasa.gov (Variable) Mesh Oil Shaft-Fed Oil Jets Carrier Bearing Drains (Rotational) Oil Jets Planet Bearing B A Feed Rotating Through
DUAL-INPUT PLANETARY DIFFERENTIAL
2 - Carrier Input (Variable A or B) National Aeronautics and Space Administration 1 - Primary Input (Fixed) www.nasa.gov
CONCLUDING REMARKS
Many more are discussed in detail in the paper.
Presented an overview of designs and current status of two-speed drive concepts developed at NASA GRC. Identified a few areas for future development. Presented an updated concept for a variable-speed gear drive based on a dual-input planetary differential.
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National Aeronautics and Space Administration www.nasa.gov National Aeronautics and Space Administration