Fluid reaction surfaces (i.e. – impellers) – With control means responsive to non-cyclic condition... – Control of drive brake or clutch
Reexamination Certificate
1998-12-02
2001-02-27
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
With control means responsive to non-cyclic condition...
Control of drive brake or clutch
C416S044000, C416S16900R
Reexamination Certificate
active
06193464
ABSTRACT:
BACKGROUND OF THE INVENTION
This application relates generally to aircraft capable of flight in both a rotary wing and fixed wing modes of flight and, more particularly, to apparatus for controlling the motion of the rotor/wing thereof.
Rotor/wing aircraft such as the aircraft disclosed in U.S. Pat. No. 5,454,530 titled “Canard Rotor/Wing” are capable of operation in both a helicopter and a fixed-wing mode of flight. In order to achieve this dual mode flight, a rotor/wing aircraft is equipped with a rotating hub, similar to the rotating hub of a helicopter, to which are attached a plurality of rotor blades extending radially outward from the hub. In the first flight regime the hub and rotor blades are rotated, in a manner similar to that of a helicopter. This enables the aircraft to move vertically, hover, and fly translationally at relatively slow speeds. In the second flight regime, the rotor is locked with the rotor blades positioned to operate as fixed wings, thereby enabling the aircraft to fly at relatively high speed configured as a conventional fixed-wing aircraft.
Historically a major obstacle to the practical implementation of rotor/wing aircraft has been the difficulties associated with transitioning between the two flight regimes, including the difficulties associated with stopping the rotating rotor blades quickly and indexing the blades precisely in position for fixed wing flight. Prior art apparatus for stopping and locking the rotor involved use of a spring-loaded shock absorber which decelerated the rotating hub during the initial stroke of the shock absorber and a rebound stop which locked the hub in position on the rebound stroke of the shock absorber. Disadvantages of the prior art approach include the size and weight of a shock absorber necessary to absorb the energy in the rotating hub and the impact loads imparted to the rotor/wing and other aircraft components.
Accordingly, what is needed is a compact, lightweight apparatus that quickly and efficiently decelerates and indexes a rotating rotor hub to an exact location without imparting unnecessary shock loads to the aircraft.
SUMMARY OF THE INVENTION
The present invention comprises a feedback-controlled braking apparatus that applies a modulated braking force that smoothly decelerates a rotating shaft such that it comes to rest at a precise location. According to a preferred embodiment of the present invention the rotor hub of a rotor/wing aircraft is coupled to a hydraulically actuated friction brake, such as a conventional disk brake comprising a brake caliper and disk brake rotor attached to the rotor main shaft. The brake caliper is supplied with fluid pressure from an electrically actuated servo valve which, in turn, is controlled by an electronic controller. A pair of sensors monitor the angular position of the rotor main shaft from which a computer calculates the angular velocity of the rotor main shaft (by computing the time rate of change of the angular position measurement). The velocity and position information is provided to the controller, which modulates the brake pressure as required to bring the rotor to a stop at exactly the right orientation relative to the aircraft. Other features such as a mechanical lock pin may be provided in order to lock the rotor main shaft in position once the brake has arrested all rotational velocity. The brake controller and mechanical lock pin device may also be configured to allow more than one “correct” orientation, such that the rotor can be locked with any one of the plurality of blades in any one of a plurality of locations. By providing active brake control, the present invention enables the rotor of a rotor/wing aircraft to be decelerated and stopped smoothly in the minimum time possible within the design stress limits of the rotor/blade/main shaft and other components and without the weight and volume occupied by prior art rotor locking apparatus.
REFERENCES:
patent: 4678401 (1987-07-01), Bradford et al.
patent: 4762196 (1988-08-01), Harado
patent: 5454530 (1995-10-01), Rutherford
patent: 5646523 (1997-07-01), Kaiser et al.
Nyhus Daniel A.
Osder Stephen S.
Bryan Cave LLP
Look Edward K.
McDonnell Douglas Helicopter Company
Rodriguez Hermes
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