Patent Application
20070284939
These features and aspects of the invention and others will be better understood after a reading of the following detailed description together with the accompanying drawings, wherein,
Referring now to the drawings, wherein the showings are for the purpose of illustrating preferred embodiments of the invention only and not for the purpose of limiting same,
A generator 40 is also mounted in wheel interior 18 and includes a generator rotor 42 connectable to wheel 16 for rotation therewith and a generator stator 44 connected to axle 14. Thus, as will be appreciated from
Output line 46 is connected to power controller 50. Power controller 50 may condition and output the AC current produced by generator 40 and/or may provide commutation to produce the direct current used by many aircraft systems. Beneficially, power controller may provide power to actuators 30 on power lines 48 so that the energy of an aircraft landing can be used to generate the power necessary for braking the aircraft.
Far more energy is produced by a typical landing than is needed to control the aircraft brakes. Therefore, power controller 50 also controls the charging and later discharging of a energy storage device 52. Energy storage device 52 may include one or more batteries; however, batteries may not charge rapidly enough to allow the capture of a substantial portion of the energy generated by an aircraft landing, which may last, for example, on the order of 30 seconds and produce approximately one megawatt of power per wheel. Therefore, energy storage device 52 alternately may comprise a bank of supercapacitors that charge more quickly than presently known batteries and that can absorb all or a substantial amount of the energy produced.
Energy stored in storage device 52 can later be used to provide power to aircraft power bus 54 for general use on an aircraft (not shown) or to actuators 30 when wheels 16 are no longer rotating rapidly enough to produce sufficient energy for controlling actuators 30, when the aircraft has nearly stopped or when the actuators 30 are used to perform a park brake function, for example. A connection to the aircraft power bus 54 provides redundancy and a source of electricity for actuators 30 in addition to the power produced by generator 40. System controller 60 controls power controller 50 and determines how the energy produced by generator 40 is directed and used.
Beneficially, generator 40 will function as a motor if current is supplied to the generator 40 on line 46, and generator 40 may therefore sometimes be referred to herein as a dual mode device to emphasize that the device may operate as either a generator or a motor. A generator such as the one disclosed in U.S. Pat. No. 5,744,896, for example, will function as a motor without modification and is an example of such a dual-mode device. Because the generator rotor is coupled to wheel 16, wheel 16 can be caused to rotate by applying power to the dual mode device 40. Therefore, wheels 16 can be pre-rotated prior to landing so that the wheel speed will substantially match the aircraft ground speed at landing to reduce wear on tires 20. Additionally, dual mode device 40 can be used to rotate wheels 16 when the aircraft is on the ground and thus reduce or eliminate the use of aircraft engines for taxiing. Moreover, because system controller 60 can drive the wheels on opposite sides of an aircraft at different speeds, an aircraft can be steered using the main landing gear wheels and reduce or eliminate the need for a separate nose-wheel steering system.
In addition, in the foregoing embodiment, generator 40 is housed in the interior 18 of wheel 16 and power controller 50 may be located on the landing gear assembly as well. With this arrangement, power lines 46 and 48 do not need to run along strut 12 but instead can be kept at the distal end of strut 12 near wheels 16. Various regulations limit the use of high-voltage wiring on an aircraft strut; because power lines 46 and 48 do not run along strut 12, they can carry high voltage without violating these safety rules. This provides greater design flexibility in the design of actuators 30 which may now, if it is desirable, be operated with high voltage.
In operation, when landing gear is deployed prior to landing, power controller 50 sends current to dual mode device 40 to accelerate wheels 16 so that the tires 20 will be rotating at approximately the ground speed of the aircraft when it lands. Shortly before landing, power controller 50 will switch dual mode device 40 into generator mode to convert the forward momentum of the aircraft into usable energy. This energy is then provided to energy storage device 52 and to actuators 30 to compress the brake stack. It will be recognized that the magnetic interaction between the generator rotor and generator stator tends to resist rotation of the aircraft wheel, and therefore the generator itself will provide additional braking for the aircraft. Controller 50 may therefore beneficially take into account the amount of braking force that will be produced by a given generator and thereby reduce the amount of frictional braking force produced by the disk stack 22 so that the total braking force produced by generator action and friction will equal the braking force commanded by a pilot or system controller, with less wear to the consumable (and often expensive) brake rotors and brake stators. A system that uses only a generator for braking is disclosed in U.S. 2005/0224642 to Sullivan, the entire contents of which is hereby incorporated by reference. Various operating methods disclosed in Sullivan may optionally be used in connection with the present invention as well.
The forgoing embodiment may be useful on wheels and landing gear systems designed to accommodate generator 40 within a wheel interior. However, existing wheels may not be able to accommodate a generator as described above. Therefore, according to a second embodiment of the invention illustrated in
Referring to
As noted above, this arrangement may be useful as a retro-fit for existing aircraft wheels that cannot accommodate a dual-mode device in their interiors. Alternately, this arrangement may be used on smaller aircraft wheels, such as nose wheels. Even if the nose wheels do not include a braking arrangement, the dual-mode device can be useful to generate power for use elsewhere in the aircraft and to operate as a motor and power the nose wheel to reduce or eliminate the need to use aircraft engines for taxiing.
A third embodiment of the invention is illustrated in
The present invention has been described herein in terms of several preferred embodiments. Obvious additions to and modifications of these embodiments will become apparent to those of ordinary skill in the art upon a reading of the foregoing description, and it is intended that all such obvious additions and modifications form a part of the present invention to the extent that they fall within the scope of the several claims appended hereto.
