1334

Item 1334

OTHER ~ Flight Dynamics - Rotor Hub - Elastomeric CVJ - Patents

US Patents, which Might be Relevant:

6,764,280 ~ Multi-bladed tail rotor hub design for coriolis relief ~ July 20, 2004 ~ Bell Helicopter Textron Inc ~ Have not yet looked into very deeply.

Abstract: A multi-bladed tail rotor assembly is disclosed that provides higher aerodynamic performance, damage tolerant design with 10,000-hour life expectancy, and which requires low maintenance through the use of composites and elastomerics. The tail rotor hub assembly includes two stacked yoke assemblies having multi-bladed teetering rotors, each mounted on a single drive mast. Each yoke assembly includes a yoke hub having a transverse bore therethrough, a bearing assembly disposed within the bore, and retention means for aligning and securing the bearing assembly within the bore. Each bearing assembly includes a trunnion portion having trunnion arms that extend outwardly from a trunnion body portion, and an elastomeric bearing disposed about each trunnion arm. The tail rotor assembly utilizes a composite twist strap flexure to accommodate collective pitch control integral with each rotor blade.

Harmonic drive system for the retraction/extension of variable diameter rotor systems Have not read it. It might be of no value.

6,454,532	September 24, 2002
Sikorsky Aircraft Corporation

Abstract: A drive system for a variable diameter rotor system includes a plurality of rotor blade assemblies with inner and outer blade segments. The outer blade segment being telescopically mounted to the inner blade segment. The VDR retraction/extension system includes a reeling system driven by a harmonic gear system. The reeling system includes a strap drum for winding and unwinding a strap attached to the outer blade segments. In operation, a control shaft drives the wave generator at a higher or lower rotational speed relative to a main rotor drive shaft assembly thereby causing the wave generator to rotate relative to the rotor hub assembly. In turn, the wave generator causes the external flex gear teeth to sequentially engage the ring gear internal gear teeth as the wave generator rotates within the flex gear. As the flex gear is mounted to the strap drum, the differential rotation between the flex gear and ring gear causes the strap drum to rotate relative the rotor hub assembly. Rotation of the strap drum thereby causes the strap to be wound about or off of the drum and, consequently, effecting retraction/extension of each VDR blade assembly.

Prop rotor hub:

US 6,296,444	October 2, 2001
Bell Helicopter Textron Inc. (Fort Worth, TX)

Abstract: ~ A prop rotor hub includes a constant velocity joint in the same plane as a prop blade yoke. Torque is transmitted from a shaft to the blades through the CV joint, hub plates attached to the CV joint, and the yoke, which is attached to the hub plates. Providing all elements in a substantially planar arrangement results in a hub assembly which has significantly less height than a traditional design. The hub itself is in-plane with the yoke, resulting in a more efficient torque transmission from the mast to the rotor.

Apparatus for imparting rotary motion through a flex point: Don't think it is of interest,

US 6,149,527	November 21, 2000
Wolford

Abstract: ~An apparatus for imparting rotary motion through a joint includes a pivotal portion which may freely pivot in two planes relative to a second portion. A rotatable shaft extends through the pivotal portion attaching to a constant velocity joint for translating rotational movement of the shaft into rotational movement of a second shaft. The pivotal portion is mounted to the second portion via a universal joint, with the constant velocity joint placed at the center of the universal joint, achieving high torque rotation.

6,062,508 Compound aircraft Search: ("constant velocity joint" OR "homo-kinetic joint") AND (helicopter OR rotorcraft OR tiltrotor) Don't think it is of interest,

6,030,177 Drive system for a variable diameter tiltrotor Probably not relevant. Search: ~ "constant velocity joint" AND elastomeric ~ 82 patents

6,019,578 Variable diameter rotor blade actuation system Search: ("constant velocity joint" OR "homo-kinetic joint") AND (helicopter OR rotorcraft OR tiltrotor)

5,740,987 Helicopter cyclic control assembly Search: ("constant velocity joint" OR "homo-kinetic joint") AND (helicopter OR rotorcraft OR tiltrotor)

5,406,859 Device for transferring power between linear and rotary motion Search: ("constant velocity joint" OR "homo-kinetic joint") AND (helicopter OR rotorcraft OR tiltrotor)

5,395,077 Multi-axial hand-operated aircraft control and method Search: ("constant velocity joint" OR "homo-kinetic joint") AND (helicopter OR rotorcraft OR tiltrotor)

5,381,985 Wingtip mounted, counter-rotating proprotor for tiltwing aircraft

5,299,912 Drive system for changing the diameter of a variable diameter rotor Search: ~ "gimballed rotor"

Constant velocity elastomeric joint:

US 5,215,502	* June 1, 1993
Assignee:	Bell Helicopter Textron Inc. (Fort Worth, TX)
*[]** Notice:	The portion of the term of this patent subsequent to April 11, 2006 has been disclaimed.

Abstract: ~ A constant velocity joint (10) is provided specifically for connecting a yoke (14) to a mast (12) in a helicopter and more generally (200) for interconnecting a first shaft (202) to a second shaft (204) for bidirectional drive. The constant velocity joint employs a carrier (40, 218) which is formed with a series of apertures for receiving elastomeric bearing assemblies (42, 80, 220). The elastomeric bearing assemblies are provided with a spherical elastomeric bearing (60) and a cylindrical elastomeric bearing (48). Certain of the elastomeric bearing assemblies connect the carrier to one of the rotating members while the remaining elastomeric bearing assemblies connect the other rotating member to the carrier. The axis of symmetry (67) of the carrier always bisects the angle of misalignment between the two rotating shafts or members to assure that a constant velocity joint is achieved.

5,145,321 Helicopter rotors with elastomeric bearings Same objective but greater complexity: Search: ~ "constant velocity joint" AND elastomeric ~ 82 patents

Equalizing stress distribution in each laminate of an asymmetrically loaded elastomeric bearing

US 4,895,354
Byrnes	January 23, 1990

Abstract ~ A hollow spherical or conical elastomeric bearing has an elliptical inner surface whose minor diameter is aligned with the resultant nonaxial load under a compressive axial load.

4,759,689 Bladed aircraft rotor with flexible blade mountings Could be similar in end result: Search: ~ "constant velocity joint" AND elastomeric ~ 82 patents

Constant velocity elastomeric bearing joint:

US 4,734,081	March 29, 1988
Bell Helicopter Textron Inc. (Fort Worth, TX)

Abstract ~ A constant velocity joint (200) for interconnecting a first shaft (202) to a second shaft (204) for bidirectional drive is provided. The constant velocity joint employs a carrier (218) which is formed with a series of apertures for receiving elastomeric bearing assemblies (220). The elastomeric bearing assemblies are provided with a spherical elastomeric bearing (60) and a cylindrical elastomeric bearing (48). Certain of the elastomeric bearing assemblies connect the carrier to one of the rotated members while the remaining elastomeric bearing assemblies connect the other rotating member to the carrier. The axis of symmetry of the carrier (218) will always bisect the angle of misalignment between the two rotating shafts to assure that a constant velocity joint is achieved.

Constant velocity elastomeric bearing joint:

US 4,729,753	March 8, 1988
Bell Helicopter Textron Inc. (Forth Worth, TX)

Abstract ~ A constant velocity joint (10) is provided specifically for connecting a yoke (14) to a mast (12) in a helicopter and more generally (200) for interconnecting a first shaft (202) to a second shaft (204) for bidirectional drive. The constant velocity joint employs a carrier (40, 218) which is formed with a series of apertures for receiving elastomeric bearing assemblies (42, 80, 220). The elastomeric bearing assemblies are provided with a spherical elastomeric bearing (60) and a cylindrical elastomeric bearing (48). Certain of the elastomeric bearing assemblies connect the carrier to one of the rotating members while the remaining elastomeric bearing assemblies connect the other rotating member to the carrier. The axis of symmetry (67) of the carrier always bisects the angle of misalignment between the two rotating shafts or members to assure that a constant velocity joint is achieved.

Elastomeric high torque, constant velocity joint ~ Of interest

US 4,714,450	December 22, 1987
United Technologies Corporation (Hartford, CT)

Abstract ~ A nearly spherical laminated elastomeric bearing has a non-circular latitudinal cross-section to accommodate high torque loads in elastomer bending rather than in shear. The nearly spherical profile of the bearing accommodates tilt primarily in shear. Both inwardly and outwardly extending lobes, or splines, are disclosed. The nearly spherical, lobed bearing is useful for a constant velocity joint.

Bladed aircraft rotor with flexible blade mountings

US 4,708,591	November 24, 1987
Roman

Abstract: ~ A bladed aircraft rotor is disclosed having blades mounted by means of flexible devices providing freedom for blade motions, at least in the flapping sense and in the pitch-change sense, without employment of flapping or pitch bearings or pivots, the rotor also being provided with a central bearingless joint for transmitting thrust forces while providing freedom for angular movement of the rotor as a whole about a center point on the axis of rotation. A constant velocity torque-transmitting system is also provided.

Tailoring tilt in an elastomeric high torque, constant velocity joint:

US 4,676,669	June 30, 1987
Assignee:	United Technologies Corporation (Hartford, CT)

Abstract ~ The tiltwise stiffness of an axially-lobed, nearly-spherical elastomeric joint is made uniform at all azimuths by contouring the axial height of the elastomer or by reducing the thickness or durometer of the elastomer at azimuths where the joint otherwise would be tiltwise stiffer, such as at the lobes. The improvement is useful in the application of the joint to a gimbal-like rotor system.

4,580,945 Helicopter gimbal rotor ~ United Technologies Corporation Search: ~ "gimballed rotor"

Abstract: Rotor tilt is permitted by two spherical elastomeric bearings, one above a hub member and one below, that have coincident centers at a tilt point (P) on the rotorshaft axis which is below the rotor plane. Positive rotor thrust is reacted by the upper bearing and negative rotor thrust is reacted by the lower bearing. Techniques for assembling the rotor system, precompressing the bearings, and limiting tilt are also disclosed.

Accommodating axial load in an elastomeric high torque, constant velocity joint ~ Of interest ~ Have hard copy

US 4,575,358	March 11, 1986
Assignee:	United Technologies Corporation (Hartford, CT)

Abstract ~ The axial load-carrying ability of an axially-lobed, nearly-spherical elastomeric joint is enhanced by offsetting the elastomer layers so that there is more elastomer to react the load in compression. The improvement is useful in the application of the joint to a gimbal-like rotor system.

4,569,629 Helicopter gimbal rotor ~ United Technologies Corporation Search: ~ "gimballed rotor"

4,566,856 Helicopter gimbal rotor ~ United Technologies Corporation Search: ~ "gimballed rotor"

Hingeless helicopter rotor with elastic gimbal hub ~ Not much if any interest; except for last three words below.

US 4,323,332
Fradenburgh	April 6, 1982

Abstract ~ A hingeless helicopter rotor including an aerodynamically shaped hub having a flexible diaphragm as its bottom wall, which diaphragm is connected to the rotor drive shaft and is elastically deformable in response to blade loading to tilt in any direction with respect to the axis of rotation, and further having at least three equally spaced helicopter blades projecting from and supported from within the hub for rotation therewith and for flexing with respect thereto in response to blade loading so that the flexible hub and the blades coact to produce a low equivalent offset rotor and minimized Coriolis effect. This is the main reason for my consideration of a Constant Velocity Joint.

3,804,552

1972-07-05 US1972000269114

Helicopters traveling in level flight are considered to be operating in a one "g" condition; that is, the rotor is producing lift equal to the vehicle weight. In a helicopter equipped with a gimbaled, teetering rotor, which cannot transmit a rotor moment into the mast head, a control moment about the aircraft center of gravity, a requirement to command a change in aircraft attitude, is obtained by tilting the rotor and hence its thrust vector. Thus, the control moment is a function of rotor thrust and tilt angle. When such an aircraft is subjected to a sudden descending maneuver, the rotor thrust will be reduced toward a zero or negative "g" condition. Consequently, the control moment capability will be reduced to zero and the aircraft becomes uncontrollable. However, the rotor is capable of producing a moment, if cyclic pitch is introduced to the rotor through a normal helicopter control system. This moment may be transmitted across a gimbal, down the supporting rotor mast to exert a controlling moment about the helicopter center of gravity by means of an elastomeric hub spring, connecting the gimbaled rotor hub to the rotor mast. This spring attaches to a first flange as part of the rotor hub yoke, and a second flange bolted to the supporting mast.

More Patents:

Number:	Date:	Title:	V
3,679,197	Jul 25, 1972	Compressive Load Carrying Bearings. ~ Lord Corporation
3,807,696	Apr 30, 1974	Concentric Tube Spring Rotor Mount
3,829,239	Aug 13, 1974	Multiple Element Journal Bearing
3,862,812	Jul 28, 1975	Rotor Blade Retention System. Lord Corporation
3,941,433	Mar 2 1976	Flexible bearing having low torque resistance.
4,105,266	Aug 8, 1978	Laminated bearing with plural modulus layer. ~ To Lord Corporation
4,986,735	Jan. 22,1991	Pitch Change Bearing System	8
4,549,850	Oct 29, 1985	Helicopter Rotors	2
5.110,259	May 5, 1992	Pitch Change Bearing System	8
5.297,874	Mar 29, 1994	Elastomeric bearing
5.601,408	Feb 11, 1997	Elastomeric bearing
3,932,004

V ~ Value or relevance (after cursory viewing only): 10 = excellent -to- 0 = useless

US Patent Aplications, which Might be Relevant:

Patent Application 20090162201

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OTHER: Mechanics - Bearing - Elastomeric

Last Revised: April 4, 2011