US3672788A - Variable pitch aerofoil blades - Google Patents

Variable pitch aerofoil blades Download PDF

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Publication number
US3672788A
US3672788A US34582A US3672788DA US3672788A US 3672788 A US3672788 A US 3672788A US 34582 A US34582 A US 34582A US 3672788D A US3672788D A US 3672788DA US 3672788 A US3672788 A US 3672788A
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United States
Prior art keywords
ring
blades
drive
shaft
blade
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Expired - Lifetime
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US34582A
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English (en)
Inventor
John Henry Ellinger
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Rolls Royce PLC
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Rolls Royce PLC
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Publication date
Priority claimed from GB29245/67A external-priority patent/GB1195961A/en
Application filed by Rolls Royce PLC filed Critical Rolls Royce PLC
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K3/00—Plants including a gas turbine driving a compressor or a ducted fan
    • F02K3/02—Plants including a gas turbine driving a compressor or a ducted fan in which part of the working fluid by-passes the turbine and combustion chamber
    • F02K3/04—Plants including a gas turbine driving a compressor or a ducted fan in which part of the working fluid by-passes the turbine and combustion chamber the plant including ducted fans, i.e. fans with high volume, low pressure outputs, for augmenting the jet thrust, e.g. of double-flow type
    • F02K3/06—Plants including a gas turbine driving a compressor or a ducted fan in which part of the working fluid by-passes the turbine and combustion chamber the plant including ducted fans, i.e. fans with high volume, low pressure outputs, for augmenting the jet thrust, e.g. of double-flow type with front fan
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D7/00—Rotors with blades adjustable in operation; Control thereof
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2220/00—Application
    • F05D2220/30—Application in turbines
    • F05D2220/36—Application in turbines specially adapted for the fan of turbofan engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2260/00—Function
    • F05D2260/70—Adjusting of angle of incidence or attack of rotating blades
    • F05D2260/74—Adjusting of angle of incidence or attack of rotating blades by turning around an axis perpendicular the rotor centre line
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2260/00—Function
    • F05D2260/70—Adjusting of angle of incidence or attack of rotating blades
    • F05D2260/76—Adjusting of angle of incidence or attack of rotating blades the adjusting mechanism using auxiliary power sources
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T50/00—Aeronautics or air transport
    • Y02T50/60—Efficient propulsion technologies, e.g. for aircraft

Definitions

  • Variable pitch aerofoil blades are provided with a gear drive having a feedback so that when the mechanism reaches an equilibrium (feathered) condition any disturbance affecting the blade causes the gear drive to. adjust the blades to cancel the efiect of the disturbance.
  • This invention relates to variable pitch aerofoil blades and more particularly to a mechanism adapted to drive such blades.
  • the present invention has particular but not exclusive application to variable pitch aerofoil blades forming part of the fan of a gas turbine engine.
  • variable pitch aerofoil blades comprise a plurality of aerofoils driven from a main shaft to rotate about the shaft axis and each mounted so that at least part of each said aerofoil or hydrofoil is rotatable about its longitudinal axis, a gear train drivingly connected to each said part for rotating the part about its longiutdinal axis, said gear train having at least one mode of operation in which it is adapted to rotate said parts about their longitudinal axes in such a manner that when the mechanism reaches an equilibrium position any disturbance affecting the aerofoils or hydrofoils causes a disturbance in the shaft rotation which then drives the gear train so as to cancel the effect of the disturbance.
  • said gear train is adapted so that the speed of response of said aerofoil blades to a disturbance may be varied.
  • Said variable pitch aerofoil blades may be adapted to be rigidly locked directly or indirectly to the shaft when said gear drive is inoperative.
  • Each said blade may be carried on a blade ring or disc, and rotation of each said blade about its longitudinal axis may be effected by one or more radial shafts which rotate in radial hearings in said disc or ring, the disc or ring being mounted for rotation with the main shift and each said radial shaft terminating in a pinion, said pinion or pinions being drivingly engaged at right angles to a common annular gear surrounding the shaft.
  • Said gear train is preferably adapted in different modes of operation to rotate the annular gear at diflferent rotational speeds.
  • FIG. 1 is a partly broken away sketch of a gas turbine engine including aerofoil section blades according to the invention
  • FIG. 2 is a partly sectioned perspective view of the blades and drive mechanism according to the invention, with a simplified geared drive for low windmilling speeds,
  • FIG. 3 is a sectional view of a further drive mechanism according to the invention used to provide a feathering drive for the aerofoil section rotor blades of the fan of a gas turbine engine for higher windmilling speeds, and
  • FIG. 4 is a perspective and partly broken away view of the main portion of the drive mechanism of FIG. 3.
  • FIG. 1 there is shown a gas turbine engine having an outer casing 81 within which there are mounted a compressor 82, combustion equipment (not shown) a turbine (not shown) and a final nozzle.
  • the compressor and turbine are drivingly interconnected and as the first stage of the compressor there is mounted a fan 83'.
  • the fan comprises a plurality of blades 84 each of which consists of an inner portion 1 and an outer portion 2 These portions are joined by a blade ring 15 which forms in effect the leading edge of the casing 81 of the main engine.
  • the fan blades 84 are surrounded by a fan cowling 85.
  • the fan blades 8% have been referred to as being single blades, the outer portions are in fact displaced circumferentially from theinner portions so that they lie half-way between the inner portions 1.
  • the mechanism for feathering these outer portions should ensure that the windmilling rotor comes to rest when the blades are fully feathered, causing a significant reduction in drag.
  • the need to split the blades must not affect the air flow into the first stage of the compressor.
  • the blade mounting and mechanism to support the blades should therefore be miniaturized so that they can be located in a slim annulus rotating ahead of the compress-or housing without obstructing it.
  • FIG. 2 illustrates a simplified configuration of the feathering mechanism and drive for a fan with low windmilling speeds.
  • the fan blade is divided into two parts by an outer blade ring 15, the inner blade portion 1 and the outer blade portion 2.
  • the relatively small root area at the blade mounting would in any case virtually preclude the installation of a suitable mechanism.
  • the outer blade portion 2 is mounted at a significant pitch angle which increases with diameter and consequently only this portion is feathered.
  • the inner blade portions 1 are mounted on an inner blade ring 16 which is driven at .17 from a shaft 18.
  • the outer blade portion 2 is subject to high centrifugal loading both along and about its longitudinal axis.
  • the blade mounting is designed to cater for these forces.
  • Blade portion 2 may be made in hollow metal or a suitable high strength plastic. In the latter case the plastic is partly embedded in a metallic mounting 3 which is part of the metallic journal 4 ribbed internally at S to minimize weight.
  • Two axial bearings 6a, 6b and end nuts (not shown) and two radial bearings 60 and 6d transfer the forces and moments actingon the blades to the outer blade ring on corresponding surfaces at 7.
  • the blade journal is also provided with a toothed perimeter 8 which acts as a wheel mating with two worm gears (only one shown) 9a, 9b at a high reduction ratio. r
  • the radial force acting on the bearings 6a and 6b is transferred in shear through four webs 10 to the end rims 12 of the outer blade ring 15. These rims are designed to take most of the centrifugal forces acting on the blades, the blade mounting and the blade drive.
  • the rims should be of minimum radial width to reduce aerodynamic drag as set out above. Their radial location coincides with the casing 51 which supports the static blades of the second and subsequent compressor stages.
  • the angle between the webs 10 equals the angle through whichthe blade portions 2 will rotate and the webs will provide suitable stops to limit the angle of rotation when high centrifugal twisting moments act on the blade portions under normal flight conditions.
  • the webs 10 also incorporate bearings for the worm gears 9a and 9b which are subject to high axial forces as well as normal gear separating forces.
  • Axial loading on the outer blade portions due to the propulsive force provides a moment tending to twist the outer ring. This force is almost completely eliminated by a small forward inclination of the bearing 7, using the radial centrifugal force to provide a correcting moment. Thus torsion on the outer blade ring is small. Torsion is resisted by boxing in the outer ring by cover plates 13a, 13b.
  • the H section of the outer blade ring ensures that either the inner or the outer part of the blade ring offers some torsional resistance and thus minimises torsionally induced stresses in the end rims 12 of the blade ring.
  • the outer section of the blade ring provides the outer blade portion mounting and encloses the blade feathering mechanism.
  • the inner part of the outer blade ring secures the inner blade portions at their tips to the outer blade ring and covers the outer blade portion end nuts mentioned above.
  • the outer blade ring is highly stressed to lighten it as much as possible. Consequently it will suffer considerable radial deformation at full speed.
  • the deformation of the inner blade ring 16 at the point of attachment 17 to the drive 18 should be small and equivalent to about one third of the stress in the outer blade ring. This will be very diflicult to ensure if the inner blade portions II are rigidly attached to the outer blade ring 15.
  • the method of feathering the outer blade portions also demands that the inner blade portions should be displaced by half a blade pitch relative to the outer blade portions. A rigid connection between the inner blade portions and the outer blade ring would cause the outer blade ring tobecome distorted (wave shaped) along the perimeter, causing high stresses both in the outer blade ring and along the inner blade portions.
  • the elastic element designed to minimize radial loading on the outer blade ring and the inner blade portions respecti'vely should primarily have only one degree of freedom thus providing a rigid tangential drive between the inner blade portions and the outer blade ring.
  • Suflicient torsional stiffness will limit undue fore and aft oscillation of the outer blades whilst restraining all axial movement.
  • the boxed-in spring flexure 14 satisfies this requirement especially as it will be torsionally weaker than the outer blade ring 15 and thus reduce torsionally induced stresses in the ring.
  • the tip of the inner blade portion 1 forms one side of an axially extending box section, the opposite side of which is rigidly attached to; the ring 15.
  • the two remaining sides are slightly flexible and allow controlled relative movement between the blade portions 1 and ring 15 in substantially only the radial direction.
  • the two flexible sides cannot lengthen or shorten any relative movement must be in the direction of the other two sides, that is the radial direction.
  • the inner blades 1 and the inner blade. ring 16 are preferably made in metal to ease manufacture and assembly although a plastic construction could eventually be used to lighten the structure.
  • assembly of the inner blade ring 16 is facilitated; the inner blades are finally held in a dovetail and if necessary shrunk into position.
  • the inner blade ring 16 is designed to minimise the radial movement of spring flexures 14 to minimize their length on one hand and to minimize axial stress at the interface 17 where drive 18 is attached to inner blade ring 16.
  • the radial surfaces of ring 16 are therefore tapered to olfer an approximate root stress of A; that in the outer blade ring and a circumferential stress /2. that in the outer blade ring.
  • the inner blade ring is thus subject to critical stressing.
  • the outer blade portion 2 is rotated via toothed wheel 8, worm gears 9a and 9b and shafts 21a and 2117 (only one shown) which are connected flexibly to the wheels 22a and 22b. Both wheels are rotated in opposite sense by a central worm 23 whose drive rotates two blade portions on each side of the worm. Thus 24 outer blade portions would require 6 worm gears 23.
  • the reduction ratio between worms 9 and wheel 8 is a compromise between the following extremes; it should be sufliciently low to ensure reasonably fast blade feathering whilst adequately reducing the torque due to the bearing friction and centrifugal twisting moment on windmilling to a low level when a self locking device is provided and the weight of flexible couplings and the shafts 21 in the high gravity field becomes acceptable.
  • the reduction ratio between wheels 22a and worm 23 is again a compromise between a minimum reduction for fast feathering and torque which permits a shaft drive 24 of adequate elasticity to be guided through the inner blades, which deflect significantly under torque at full speed.
  • Intermediate bearings may support the drive which terminates in pinion 26.
  • the pinion is mounted in an internal bearing 27 which is adequately connected at 28 with bearing 29 of bevel wheel 30 through a sleeve which is independently mounted for inner blade ring 16 and thus is not susceptible to the high centrifugal loads acting on it.
  • gear train has its own feed back system and requires no attention by the operator or complex monitoring equipment.
  • This dnive will be seen to be an exceptionally light epicyclic system which has low mechanical efliciency. This will make it relatively insensitive to hunting, whilst avoiding high machining tolerances.
  • the wheels are driven from a worm 111 which are items 22 and 23 in FIG. 2.
  • This worm comprises an outer portion mounted on bearings from a blade ring 112 and driven by diaphragm 113 which is splined to a radially extending drive shaft 114.
  • the drive shaft 114 extends through an inner fixed portion 115 of the fan blades to the blade ring 112.
  • the inner portion 115 is supported from an inner blade ring 116 and the shafts '114 extend through apertures 117 in this inner blade ring.
  • each bevel pinion 118 is adjustably mounted in two axial bearings 120a and 12%, which transfer the centrifu-gal load acting on the drive shaft 114 on to the bearing mountings.
  • Each bevel pinion is radially mounted on two bearings 121a and 121b.
  • the pinions 118 are mounted at a fixed radius about the shaft 122 of the engine, this shaft being the main drive shaft for the fan blades.
  • the shaft 122 is of large diameter and is hollow, being shown broken down the middle in the drawing for convenience.
  • the shaft 122 carries drive from the turbine of the engine to the inner blade ring 116 and hence to the inner blade portions 115, the outer blade ring 1 12 and the remainder of the fan blades.
  • the shaft 122 is attached through a flange 123 to a second part of the shaft 124 which runs in a bearing 125 which is mounted in a static blade ring 126.
  • a bevel gear wheel 127 Coaxial with the shaft 122 there is a bevel gear wheel 127 having a sleeve-like axial extension 128 forming a drive sleeve.
  • the extension 128 and the bevel 127 are mounted on radial bearings 129a and 1291). These bearings are widely separated and hence allow for the large diam eter of the bevel wheel 127.
  • Axially adjustable bearings 130a and 130 h control the extent of the engagement between the bevel wheel 127 and the pinions 118.
  • the bearings 130a and 1311b lie between the bevel wheel 127 and a locking ring 131 screwed to the bevel 127 and a threaded ring 132 which is screwed to a pinion carrier 109.
  • a supplementary radial bearing 1300 between the bevel 127 and pinions i118 ensures concentricity of engagement between the bevel and the pinions.
  • the bearings 129a and 12% are carried from a tubular member 133' which surrounds and is attached at one extrernity to the shaft :122, and it will be appreciated that the tubular member 133 is not subject to the torque loads which affect the shaft 122.
  • Cut on the inside of the eccentric sleeve 136 is a ring of internal gears 13 9 which are adapted to mesh with either of the rings 134 and on the extension 128 of the bevel 127.
  • a further gear ring 140 is cut on the extremity of the eccentric sleeve 136 at a different radius to the ring 139.
  • the ring 140 is adapted to mesh with a ring of gears 141 on the tubular member 133, and the positions of the rings 139 and 140 are so chosen with respect to the rings 141 and 134 that when the ring 140 meshes with the ring 141 the ring 139 also meshes with the ring 134.
  • a clutch face 142 which is shaped to act with a second clutch face 143 mounted from the static blade ring 126.
  • the clutch faces 142 and 143 engage one another when the eccentric sleeve 136 has been moved axially, sufficiently to engage the gear ring 139 with the gear ring 135.
  • a number of hydraulic rams 144 which operate through rods 145 on to spherical bolts 146 which engage in a groove 147.
  • the rods 145 are held peripherally against cantilever loading by a spacer ring 148.
  • the ring 148 is located against circumferential movement by static cantilever 158 which projects through a fitted aperture in the ring.
  • a ring 149 having a set of splines 150 which engage with external splines 151 on the tubular member 133.
  • the ring 149 is carried in bearings 152a and 152b from the inner surface of the cylindrical extension 128 of the bevel wheel 127.
  • the four extensions '153 carry commutator rings 154 and 155 outside the cylindrical extension 128 and coaxial with it, these commutator rings carrying axial bearing surfaces.
  • the rings 154 and 155 engage at one side in a groove 156 formed in the eccentric sleeve 136 so that the commutator rings 154 and 155, the projections 153 and the ring 149 together move axially with the eccentric sleeve 136.
  • a segment extension 157 is provided which seats in the groove 156 at the side distant from the engagement between the groove 156 and the commutator rings 154 and 155.
  • the extension piece 157 is mounted on a static centilever 158 carried from the static blade ring 126, and at its radially inner extremity it engages with the commutator rings 154 and 155.
  • the gear system described has three modes of operation and these are described below.
  • the eccentric sleeve 136 is in the ax al position shown in FIG. 3 of the accompanying drawings.
  • the shaft 122 drives the inner blade ring 116 and also drives the bevel wheel 127 by way of the splines 150, 151 the ring 149 and the projections 153 from the ring 149 which engage with the axial slots on the cylindrical extension 128 of the bevel wheel 127.
  • the apertures 117 in the inner blade ring 116 form in effect the cage bearings for the equivalent epicyclic drive. It will be seen that in this condition the pinions 118 and the bevel wheel 127 rotate at the same angular velocity and therefore the shafts 114 will not rotate about their axes and will not attempt to drive the fan blades about their axes.
  • the fan blades will require to be feathered so that the large fan can windmill. Once such a failure occurs there will no longer be any substantial torque or centrifugal loading on the inner portions of the blades and the blades and the shafts 114 will straighten. The drive will then be able to transmit substantial torque through the diaphragm 113 on the Worm 111. Also the engagement between the bevel wheel 127 and the pinions 118 is then devoid of significant deformation. Since the worms which drive the outer portions of the blades do not allow any feedback of torque, the entire gear system is unloaded.
  • a control system (not shown) will cause the rams 144 to push the eccentric sleeve 136 axially against the action of a synchromesh baulking device (not shown) in the eccentric sleeve.
  • This device could take the form of a ring of spring loaded balls retained in radial drillings in the eccentric sleeve such that once the sleeve increases to a certain speed the balls retract into the eccentric sleeve and allow free axial movement of the sleeve.
  • the sleeve is then allowed to slide axially until the sets of teeth 139' and 134; and 141 engage, simultaneously causing the splines and 151 to disengage.
  • the rams 144 are again energised and the eccentric sleeve 136 again moved axially so as to disengage the sets of teeth 140 and 141 and 139 and 134 while engaging the teeth 139 and 135 and the clutch faces 142 and 143.
  • the eccentric sleeve 136 is progressively arrested hence also arresting the bevel wheel 127 by way of the sets of teeth 139 and 135.
  • the pinions will finally be subjected to an epicyclic drive between the stationary bevel wheel 127 and the inner bearing ring 116 driven from the shaft 122.
  • the pinions 118 will temporarily increase their speed considerably and feather the fan blades more rapidly.
  • either the inner blade ring will come to rest because the blades have come to rest or the blades will feather excessively (due to inertia of the outer blade ring) when the blade ring will reverse rotation and oscillate until it has hunted to rest. Any change in aircraft speed will tend to upset the equilibrium condition of the blade setting and will cause the blades to rotate the shaft 122 hence providing a feedback of an epicyclic drive to the pinions 118 which will vary the angle of the blades in a sense to bring the system back to equilibrium.
  • a first sub assembly comprises the six pinions 118 which are mounted in a casing 109 and adjusted to their radial and axial position on the bearings 120 and 121.
  • the casing 109 with the pinions attached is then mounted into the inner blade ring 116 and locked circumferentially by a number of sleeves 160 which are screwed through the apertures 117 by inserting a screw driven through the bearing 161 of the drive shafts 114.
  • the inner'blad'e portions 115 are then assembled to the inner blade ring 116 and the outer blade ring 112 fitted over the portions 115.
  • the drive shafts 114 are then pushed radiallyinwards and secured in place through the splined diaphragm disc 162 by an end nut 119.
  • the intermediate shaft bearing 161rests in the inner blade ring 116, and the worm 111 and the wheels 110 of the outer blade ring can be assembled prior to fitting splined diaphragm 113; I
  • the second sub assembly comprises the bevel wheel 127 into which the ring'149 is fitted internally (it may be necessary to mount the rear bearing 12% in a ring which is detachable to facilitate this assembly).
  • the pro jections 153 are assembled'and locked by the rings 154 and 155.
  • the bevel. wheel casing bearing assembly comprising the ring 132 and the locking ring 131 and various intermediate bearings is assembled and given an adequate preloading.
  • the segmental extension 157 is mounted on the rings 154 and 155 and the annulus 136 slid over the assembly and locked axially by a locking ring 163 which also defines the space 156.
  • the spherical bolts 146 and the rods 145 are next fitted into place and the spacing ring ring 148 is balanced in position.
  • the splined sleeve 133 is inserted into the assembly.
  • the third sub assembly consists of a perforated housing 138 which mounts the six rams 144 and which is to be mounted on the static blade ring 126 with various hydraulic pipes installed.
  • the segmental cantilever 158 is attached to the housing 138.
  • the first sub assembly is now offered to the second sub assembly and the tubular member 133 is mounted on the shaft 122. Finally the bevel wheel 127 is engaged with the bevel pinions 118 and is adjusted and locked by the ring 132.
  • each ram can be assembled in turn, to facilitate assembly.
  • shaft portion 122 is bolted to the shaft portion 124 through a flange 123, which is bolted through the bore of the shaft 122, and the assembly is then complete.
  • variable speed gear train has been entirely mechanical and relied upon the engagement of gear wheels it would be possible to use instead a clutch Whose degree of slip could be precisely controlled.
  • a clutch might well make use of a magnetic friction material which provides a controlled degree of coupling ac- 10 cording to the magnetic field imposed upon it.
  • An electrical control system would best be used for a device.
  • the invention could be used for other applications than those described; thus other types of blades such a hydrofoils could be arranged to be feathered by the drive by the invention.
  • the stationary condition of the fan will not be the condition of least drag and under these conditions it may be required to halt rotation of the fan blades before they have fully feathered.
  • a system could be used in which arevolution counter of some kind is connected to the concentric sleeve 136. This revolution counter would be arranged to count the number of revolutions of the sleeve 136 hence indirectly counting the number of revolutions of the bevel pinions 118 and hence registering the angle of rotation of the fan blades about their longest axis.
  • This revolution counter would be connected to the hydraulic system for the rams 144 so that when the fan blades have turned to the required minimum drag position the rams operate the concentric sleeve 136 to reengage the splines 150, 151 and hence re-establish drive between the shafts 122 and the inner blade ring 116.
  • the system would be arranged that the rams could be operated a second time so as to go through the cycle outlined in column 8, lines 41 to 75, and column 9, lines 1 and 2, and eventually totally feather the :blades.
  • the bevel wheel 127 rotates slower than the shaft 122. If it were arranged that the bevel wheel rotated faster than the shaft, the epicyclic drive to the pinions 118 would be reversed and such a system might prove valuable in enabling the pitch of the fan blades to be varied in either direction to suit differing aerodynamic conditions of the fan. Such a reversal could be achieved by having a further set of teeth similar to 134 and 135 on the extension 128, this set of teeth having a different number of teeth from those on the ring 134.
  • the ratio between the shaft 122 and the extension 128 is very close to 1:1. This leads to the possibility of providing the reversal of drive by altering the number of teeth on the ring 139 and thus causing the reversal of the direction of drive of the pinions. In fact an increase of a single tooth in the number of teeth in the ring 139 would effect this reversal. Therefore by arranging that the ring 139 has a variable number of teeth complete-control of the angle of the fan blades can be achieved, with pitch variation in both directions being provided.
  • a variable pitch aerofoil assembly comprising:
  • main drive shaft means having said plurality of aerofoil blades operatively attached thereto so that the blades can be rotated about the axis of said main drive shaft means
  • variable ratio gear train means providing a plurality of modes of operation so that the speed of response of the aerofoil blades to a disturbance may be varied
  • said variable ratio gear train means including (a) pinion means operatively associated with each of said aerofoil blades and constrained to rotate with rotation of said main drive shaft means, (b) a bevel gear wheel means carried coaxially with said main drive shaft for meshing with said pinion means, (c) interconnection means for normally interconnecting said main drive shaft means with said bevel gear wheel means so that the bevel gear wheel means is driven normally at the same speed as is the main drive shaft means, and ((1) means for varying the rotational speed of said interconnection means with respect to said main drive shaft means, and
  • arresting means for arresting said bevel gear wheel means during emergency conditions.
  • said arresting means comprises a clutch face carried from said sleeve and adapted to engage with a clutch face carried from static structure to partially or wholly arrest the sleeve, thereby partially or wholly arresting the annular ,g'ear wheel and forming an epicyclic drive.
  • said arresting means includes a clutch face carried bysaid eccentric annulus and which is adapted to engage witha clutch face carried by static structure to arrest or retard the eccentric annulus, there being at least onehydr aulic piston and cylinder mounted from the static structure and adapted to move said annulus axially to effect engagement and, disengagement of said clutch faces, a

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
US34582A 1966-12-05 1970-05-04 Variable pitch aerofoil blades Expired - Lifetime US3672788A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB29245/67A GB1195961A (en) 1966-12-05 1966-12-05 Variable Pitch Aerofoil Blades.
GB48910/67A GB1195964A (en) 1966-12-05 1966-12-05 Fan.
GB5441766 1966-12-05

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US3672788A true US3672788A (en) 1972-06-27

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US34582A Expired - Lifetime US3672788A (en) 1966-12-05 1970-05-04 Variable pitch aerofoil blades

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DE (1) DE1601640A1 (de)
FR (1) FR1553936A (de)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3866415A (en) * 1974-02-25 1975-02-18 Gen Electric Fan blade actuator using pressurized air
US3893789A (en) * 1973-02-21 1975-07-08 United Aircraft Corp Pitch change actuator for a variable pitch fan propulsor
US3895884A (en) * 1974-07-05 1975-07-22 United Aircraft Corp Torque sensitive pitch lock
US3904315A (en) * 1974-07-31 1975-09-09 United Aircraft Corp Pitch change signal means with differential gearing
US3910721A (en) * 1973-01-12 1975-10-07 Rolls Royce 1971 Ltd Pitch varying mechanisms for bladed rotors
US4578019A (en) * 1982-05-28 1986-03-25 The Garrett Corporation Ram air turbine
FR2582719A1 (fr) * 1985-05-31 1986-12-05 Gen Electric Moyen de transmission d'energie
US4738590A (en) * 1986-09-09 1988-04-19 General Electric Company Blade pitch varying mechanism
US4738591A (en) * 1986-09-09 1988-04-19 General Electric Company Blade pitch varying mechanism
EP0392401A1 (de) * 1989-04-10 1990-10-17 Mtu Motoren- Und Turbinen-Union MàœNchen Gmbh Absperreinrichtung für Gebläse, insbesondere Gebläse-Staustrahltriebwerke
US5152668A (en) * 1990-07-23 1992-10-06 General Electric Company Pitch change mechanism for prop fans
US5154372A (en) * 1990-07-23 1992-10-13 General Electric Company Torque multiplier for aircraft propeller
US5154580A (en) * 1990-07-23 1992-10-13 General Electric Company Propeller pitch change mechanism
US5156648A (en) * 1990-07-09 1992-10-20 General Electric Company Prop-fan pitch-change mechanism
US5174716A (en) * 1990-07-23 1992-12-29 General Electric Company Pitch change mechanism
US5242265A (en) * 1990-07-23 1993-09-07 General Electric Company Aircraft pitch change mechanism
US20110129365A1 (en) * 2009-11-30 2011-06-02 I-Huang Chen Electric fan
US20220099098A1 (en) * 2019-12-18 2022-03-31 Ie Assets Gmbh & Co. Kg Fan wheel

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3910721A (en) * 1973-01-12 1975-10-07 Rolls Royce 1971 Ltd Pitch varying mechanisms for bladed rotors
US3893789A (en) * 1973-02-21 1975-07-08 United Aircraft Corp Pitch change actuator for a variable pitch fan propulsor
US3866415A (en) * 1974-02-25 1975-02-18 Gen Electric Fan blade actuator using pressurized air
US3895884A (en) * 1974-07-05 1975-07-22 United Aircraft Corp Torque sensitive pitch lock
US3904315A (en) * 1974-07-31 1975-09-09 United Aircraft Corp Pitch change signal means with differential gearing
US4578019A (en) * 1982-05-28 1986-03-25 The Garrett Corporation Ram air turbine
FR2582719A1 (fr) * 1985-05-31 1986-12-05 Gen Electric Moyen de transmission d'energie
US4738591A (en) * 1986-09-09 1988-04-19 General Electric Company Blade pitch varying mechanism
US4738590A (en) * 1986-09-09 1988-04-19 General Electric Company Blade pitch varying mechanism
EP0392401A1 (de) * 1989-04-10 1990-10-17 Mtu Motoren- Und Turbinen-Union MàœNchen Gmbh Absperreinrichtung für Gebläse, insbesondere Gebläse-Staustrahltriebwerke
US5156648A (en) * 1990-07-09 1992-10-20 General Electric Company Prop-fan pitch-change mechanism
US5152668A (en) * 1990-07-23 1992-10-06 General Electric Company Pitch change mechanism for prop fans
US5154372A (en) * 1990-07-23 1992-10-13 General Electric Company Torque multiplier for aircraft propeller
US5154580A (en) * 1990-07-23 1992-10-13 General Electric Company Propeller pitch change mechanism
US5174716A (en) * 1990-07-23 1992-12-29 General Electric Company Pitch change mechanism
US5242265A (en) * 1990-07-23 1993-09-07 General Electric Company Aircraft pitch change mechanism
US20110129365A1 (en) * 2009-11-30 2011-06-02 I-Huang Chen Electric fan
US20220099098A1 (en) * 2019-12-18 2022-03-31 Ie Assets Gmbh & Co. Kg Fan wheel
US11708836B2 (en) * 2019-12-18 2023-07-25 Ie Assets Gmbh & Co. Kg Fan wheel

Also Published As

Publication number Publication date
FR1553936A (de) 1969-01-17
DE1601640A1 (de) 1970-04-09

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