AU2005337836A1 - Magnetically induced aircraft landing wheel rotation - Google Patents

Description

WO 2007/048164 PCT/AU2005/001646 MAGNETICALLY INDUCED AIRCRAFT LANDING WHEET ROTATION The invention relates to improvements in aircraft landing wheel assembly. These improvements relate specifically to controlling the forward rolling speed of the wheel and tire assembly prior to landing and where required applying added retardation to the wheel after landing. 5. The aim is to adjust the wheel and tyre assemblies forward rotational speed prior to landing so as to reduce tyre skidding, reduce impact loading on the landing gear, reduce tyre wear, thus reducing the chance of sudden tyre failure and reducing impact wear and tear on wheels and landing gear. Safety is potentially improved and maintenance costs reduced. 10. The objective of the system is to precisely control the forward rotational speed of the aircraft landing wheel-tyre assemblies in relation to the ground speed just prior to landing, by means of an imposed electric current specifically to induce magnetic field forces located on or within components of the wheel , brake assembly and components of the associated landing gear, such components being contained or partially contained within the wheel and or brake 15. assembly and being either an attachment to such items or forming part of such items during manufacture. This does not necessarily mean that all wheels will spin at a forward rotation rate equal to ground speed at the point of tyre impact with the tarmac, although this rotation speed may be 20. optimum for some aircraft. It may be found desirable to have the landing wheels and thus tyres spinning at a rate either faster, equal to or slower than the rotation rate equivalent to ground speed of the rolling tyre. 25. The optimum rotation speed of the aircraft wheels just prior to landing will be determined by the type of aircraft, the runway pavement condition, dry, wet, icy, hot or cold, the type of pavement and friction characteristics. The optimum wheel rotation speed, for the particular aircraft and runway pavement 30. conditions can be adjusted to afford improved stability of the aircraft under a variety of conditions. The tyre making contact with the runway can have a contact speed differential either faster, slower or equal to the actual ground speed in order to promote stability. The ground speed of the aircraft is already accurately monitored by the aircraft instruments. 35. Wheel rotation rate sensors are already readily available on aircraft brake and brake antiskid systems. These systems are easily modified to register rotation speed which for a known tyre circumference can be converted directly to rolling speed and compared directly with ground speed. 40. The aim is to adjust or fix the rotation rate of the landing wheels either automatically or manually to correspond proportionally faster or slower or equal to ground speed as determined by the optimum for the particular aircraft and pavement conditions. 45. A fixed wheel rotation speed set to a median speed which approximates to the landing speed of a particular aircraft type under most conditions may prove satisfactory and to afford suitable benefits without the complexity of variable speed control.

WO 2007/048164 PCT/AU2005/001646 2 It may also be considered that with present aircraft a certain amount of energy may be absorbed by the normal wheel / tyre impact and skidding on the pavement. This energy absorption may be considered to offer a small amount of braking to the aircraft which would not occure if the wheels are already spinning when pavement contact is made. 5. To counteract this small loss of braking energy the system proposed will offer the option of a form of "regenerative braking" or "reverse drive" which will assist the normal brake system of the aircraft throughout the brake cycle thus more than offsetting the effects of wheel pre rotation on stopping distances. 10. Wheel rotation is to be achieved either, electrically, or electro mechanically where by an electric current will create field forces that induce rotation of mechanical components of the wheel assembly at a controlled or predetermined rate of rotation. The wheel assembly shown in figures 1 and 2 in this instance refers to the wheel rim and wheel support face and the brake stack or heat stack (rotors I and stators 2 ), the brake actuating components 15. (piston housing 3 ), (or electric brake actuator) and the torque tube and strut mounting points for the wheel and brake assembly. Present commercial, aircraft, freight aircraft and military aircraft utilise a wheel, tyre, axil, and brake assembly which will be referred to as the landing wheel assembly. This landing 20. wheel assembly will be improved to incorporate electric field coils, and or electronic components, and or permanent magnets such that an imposed electric current will create forward rotation of the wheel tyre assembly due to forces set up between the static and rotating components of the landing gear and wheel and brake assembly. 25. This system may be fully or partially contained within the wheel. The static components of the system are the strut which supports all loads including the aircraft weight, the torque tube which absorbs the torque loads from the rotors and stators to the strut., the piston housing or brake actuating components 3 and their support frame plus all stators 2 30. and support structures and brake stack housing are static components. The static components can be adapted to support or house the primary circuit of the active or primary magnetic field generating medium which in the most simplified case would be field windings on or attached to one of the static components or formed into said component. 35. These field windings could be formed as coils or cylindrical field windings 7 around the outer circumference of the brake piston housings 3 and induce magnetic fields which impose reactive forces on opposed magnetic fields associated with components attached to the inner rim of the rotating wheel assembly 11. 40. Alternatively field windings can be mounted on components associated with the brake stack housing 8,9,10 and react with opposing magnetic fields attached to or formed into rotating components associated with the wheel or hub 12,13,14.or attached to a stator 5 of the brake stack and react with a rotor 6 in close proximity which is modified to maintain magnetic fields. 45. The field windings will generally be set out in an even radial pattern of placement around the perimeter of the static support structure.

WO 2007/048164 PCT/AU2005/001646 3 All static components, strut, torque tube, brake piston housing 3 , brake piston support frame, brake stack housing ,or one of the stators 5 , in the brake stack can be adapted or manufactured to incorporate or mount a primary field winding. An electric brake actuator can be used in place of the brake piston housing without alteration to the basic field winding arrangement. 5. Field windings may take the form of a flat armature winding disc or a winding of cylindrical form which may or may not incorporate an ironless air gap and can be attached directly to a stator 5 or the brake stack housing structure 4 , torque tube or brake support structure.. 10. The radius of placement of the static field winding or flat armature will be dependant upon the rotating component on which the static field winding will impose field forces. Rotating components which can interact with the imposed field forces eg. permanent magnets, or magnetically 'soft' material have possible placement locations which include the inner or 15. outer perimeter of the wheel rim. 11, 12, 13 the outer perimeter of the hub 14 or one of the rotors 6 in the stator / rotor, brake stack . The specification of electric drive system to be used is open to wide variation, since there is a wide variety of electric drive systems which would suite the purpose. 20. A brushless D.C drive system with static field windings and high flux density permanent magnets attached radially to and spaced around the perimeter of the rotating component is probably the simplest method of achieving all requirements of torque, and precise rotational speed control. 25. This is one of the layouts described in detail in this document. However Brushless A.C drive system types and A.C Induction drive systems with suitable inverter, and or micro processor control will serve the purpose. The rotating components of the electric drive system can be permanent magnets set around the rotating component or as a disc or magnet ring made up of 30. separate magnets attached to a rotor or the wheel rim or hub. Toothed blocks of magnetically soft material may replace the magnets as may induction coils or windings depending on the chosen electric drive type to be employed. This material may be attached to or formed into the structure of the rotating component. 35. There is a very large array of electric drive types whereby the basic mode of operation eg. AC induction or DC brushless system can serve as the mode of operation of the drive system incorporated into the aircraft wheel assembly and providing precise forward wheel speed rotation prior to landing and the option of retardation assistance after initial touch down and brake application. 40. The basic component layout of a primary electric field giving rise to magnetic fields incorporated on or within the static components of the wheel assembly and an interactive magnetic field due to, permanent magnets or induced in field windings or electro-magnetically excited materials incorporated on or within the rotating components of the wheel assembly, are 45. the basic design criteria.

WO 2007/048164 PCT/AU2005/001646 4 The aim of the claims is not to establish a specific type of electric drive type of which an abundant array exist. Brushless DC or AC Motors, DC Servo motors, electric drive systems with a variety of control units can adequately serve the purpose of inducing controlled forward rotation of the aircraft landing wheels and if necessary applying some degree of braking 5. retardation after landing. The aim of the claims is to establish a means of adapting well known electric motor drive systems technology to form an electric drive system specifically designed for achieving forward rotation of aircraft landing wheels which it is believed differs markedly from any 10. previous proposals for prerotation of aircraft landing wheels. The drawings figure 1 and figure 2 of the drawing page 1/3 and 2/3 show the component layout of one of a series of main landing wheels associated with the landing gear typically found on large passenger aircraft. 15. The primary components are numbered on figures 1 and 2 as are the locations of the incorporated electric drive components. Figure 1 shows a typical wheel , rim , hub , assembly of rotating components while figure 2 20. depicts the brake stack , rotors , and stators along with piston assembly . The pistons, mountings and housings remain stationary while the rotors rotate with the wheel rim and hub assembly. Figure 3 shows the combination of Figure 1 and Figure 2 which represents the assembled 25. state of the Aircraft Landing Wheel Assembly.

Claims (11)

1. An aircraft landing wheel assembly shown in figures 1, 2 and 3 suitably modified or redesigned such that an imposed electrical current in strategically placed field windings or coils or electrically excited material gives rise to primary magnetic fields and such items are attached to or incorporated into static components of the aircraft wheel and or

5. brake assembly including their mounting structures such that the primary magnetic field forces interact with reactive magnetic field components attached to or incorporated into rotating components of the aircraft wheel assembly, brake and wheel hub so as to create rotational forces on the rotating components creating controlled forward rotation of the aircraft landing wheels prior to contact with the runway.

10. 2. The aircraft landing wheel assembly of claim I whereby the primary magnetic field is electrically induced in a flat disc field winding or flat stator winding attached to or formed into the static housing of the Brake Stack in location 8, 9 of figure 2 and reacts with a magnetic field created by a flat ring of permanent magnets attached to or formed

15. into the inner wheel rim around the perimeter at approximately equal radial spacing defined by the position 12, 13 on figure 1 3. The aircraft landing wheel assembly of claim 2 whereby the permanent magnet ring of location 12, 13, is replaced by a suitable magnetically soft material or such a material

20. enhanced with induction field windings in which a secondary magnetic field is induced by the primary magnetic field of the flat stator winding thus creating the necessary rotational forces. 4. The aircraft landing wheel assembly of claim 1 whereby a thin cylindrical field winding is

25. supported on or formed within the inner static casing of the brake stack in location 10 and the opposed reactive magnetic field is a cylinder of permanent magnets laid out around the wheel hub in location14 and either attached to the wheel hub or incorporated into the surface of the hub during manufacture.

30. 5. The aircraft landing wheel assembly of claim 4 whereby the permanent magnets laid out around the hub of the wheel in location 14 are replaced with suitable magnetically soft material, or such material enhanced by induction coil windings, to allow induction of secondary magnetic fields resulting from the primary fields 10 and causing rotational forces.

35. 6. The aircraft landing wheel assembly of claim 1 whereby the primary magnetic field is electrically induced in a series of field windings in the form of approximately equally spaced coils located around the perimeter of positions 7 or a thin cylindrical field winding located around this perimeter which would generally be additional components attached to

40. existing brake piston assemblies or their mountings or formed as part of these assemblies during manufacture. The primary magnetic field 7 reacts with a magnetic field created by a ring of permanent magnets which form a cylindrical ring attached to extensions on the inner wheel rim in location 11 of figure 1 or formed into wheel rim extensions during rim manufacture.

45. 7. The aircraft landing wheel assembly of claim 6 whereby the cylindrical ring of permanent magnets in location 11 is replaced with suitable magnetically soft material or such material with induction field coil winding enhancement such that the primary magnetic field 7 induces secondary reactive magnetic fields in the magnetically soft material so as

50. to achieve rotational forces on the rotating components of the wheel. WO 2007/048164 PCT/AU2005/001646 6 8. The aircraft landing wheel assembly of claim 1 where by the primary magnetic field is electrically induced in a flat disc shaped field winding or a series of field winding coils set out within the surface of one or more stators as shown in Figure 2 item 5 and whereby a rotor in close proximity to the modified stator will have a disc of thin permanent magnets 5. set into or formed into the rotor face around the circumference of the rotor face 6. 9. The aircraft landing wheel assembly of claim 8 whereby the permanent magnets set into the rotor 6 are replaced with magnetically soft material or magnetically soft material enhanced with field windings or coils, so as to act as secondary reactive magnetic field 10. medium induced by the primary fields of the stator 5 thus giving rise to rotational forces. 10. The aircraft landing wheel assembly of any one of claims 1, 2, 3, 4, 5, 6, 7, 8 and 9 whereby the electrical current and resulting magnetic fields, can be controlled so as to allow both forward drive of the landing wheel at controlled rotational speed prior to 15. landing and a controlled reverse drive or brake assistance retardation capacity upon landing to assistance retardation capacity upon landing to assist the primary aircraft braking system. 11. The aircraft landing wheel assembly of any one of the claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 20. linked to micro processing equipment which is in turn linked to the aircrafts own micro processing equipment or aircraft computer system associated with aircraft ground speed and A.B.S. or Antilock Brake equipment suitably adapted for monitoring wheel rotation rate in relation to ground speed and having the ability to automatically adjust forward wheel rotation rate prior to landing and the degree of retardation assistance after landing. 25. 12. Figure 3 shows the combination of Figure 1 and Figure 2 which represents the assembled state of the Aircraft Landing Wheel Assembly.