Fluid reaction surfaces (i.e. – impellers) – With control means responsive to non-cyclic condition... – Plural diverse condition responsive
Reexamination Certificate
2003-05-19
2004-01-06
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
With control means responsive to non-cyclic condition...
Plural diverse condition responsive
C416S048000, C416S155000
Reexamination Certificate
active
06672835
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to the control and governing of aircraft propeller blade pitch, and more specifically, to a method and apparatus for a self-contained variable pitch and/or constant speed propeller including provisions for feathering and reverse pitch operation. The invention is further applicable to marine propellers, windmills, and axial impellers for ventilation and other air handling applications such as wind tunnels. Briefly, the present invention provides a method and apparatus contained within an aircraft propeller that enables adjustment of the propeller blade pitch setting to a selected angle, or the maintenance of a selected rotational velocity via adjustment of blade pitch.
BACKGROUND OF THE INVENTION
The advantages of an in flight controllable pitch propeller have been well known since early twentieth century. As such, there have been many systems developed for controlling aircraft propeller blade pitch. Most such systems have in common at least the following three requirements: (1) the current operating conditions of the propeller must be known to the system—for a controllable pitch system, this would be the current blade pitch setting, whereas for a constant speed system utilizing a governor, this would be the current angular velocity and the angular acceleration, or some function thereof; (2) the desired propeller operating conditions must be known—this would be the selected blade pitch setting for a variable pitch unit, or the selected angular velocity for a constant speed unit; and (3) some form of power must be available to operate the blade pitch change mechanism.
One of the most successful propeller blade pitch changing systems has been the hydraulic system, originally developed by Hamilton Standard, wherein the hydraulic system routes oil pressure from the aircraft engine, or gearbox, through the propeller shaft to provide a means for changing blade pitch. The oil pressure in the propeller shaft is controlled by a governor, which in turn, adjusts the blade pitch to maintain a selected engine rotation speed.
Other methods and systems include various electric systems, wherein electrical power to control the blade pitch is sourced from the aircraft electrical system and transferred to the propeller by means of slip rings or brushes. Mechanical systems for controlling blade pitch have also been utilized, wherein a bearing ring is utilized to transfer motion from a device mounted on the airframe to the propeller for blade pitch changing purposes.
All of the previous systems, however, share the same disadvantage; they problematically depend upon having to transfer the requisite power for blade pitch change from a fixed portion of the engine, or airframe, to the rotating propeller, thus making propeller installation significantly more complex. Specifically, the hydraulic system requires an oil passage through the propeller shaft to the propeller and associated blades, wherein the oil pressure within the propeller shaft must be regulated, and in some cases boosted, by a governor attached to the engine or gearbox. Typically, the governor requires its own set of oil passages, as well as the appropriate mounting pad and drive, thus further complicating, propeller installation. Additionally, hydraulic systems must be effectively sealed to prevent loss of propeller control or even worse, loss of engine or gearbox oil, and therefore, require frequent maintenance for preservation of the system.
With regard to electrical systems, the slip rings or brushes utilized for transferring power to the propeller require frequent replacement and adjustment, are generally unduly expensive, and therefore increase overall maintenance costs. Furthermore, for systems integrity and operational capacity, such electrical systems must be well shielded from electrostatic and/or electrical environmental implements, such as lightning, and/or from other sources of electrical disturbance.
Although relatively structurally simple, mechanical systems are often difficult to implement without incurring significant weight and maintenance problems. In particular, the operational nature of the rotating-to-fixed bearing assembly, utilized for transferring mechanical motion from the engine or airframe to the propeller, generally calls for frequent maintenance, and therefore overrides any benefit otherwise derived from the simplistic installation and design of such a system.
Essentially, in addition to the aforementioned deficiencies, disadvantages and impracticalities, the above-discussed blade pitch changing systems suffer, in general, from added complexity, maintenance requirements, and safety of flight issues, as functional operation of each system burdensomely requires that the blade pitch setting information and the requisite power to change such blade pitch be transferred hydraulically, electrically or mechanically from the fixed engine or airframe to the rotating propeller, thus overly complicating propeller installation.
Therefore, it is readily apparent that there is a need for a self-contained variable pitch and/or constant speed propeller that requires no direct contact of any type, hydraulic, pneumatic, electrical, or mechanical, between the fixed engine or airframe and the rotating propeller, thus facilitating propeller installation and reducing overall system maintenance.
BRIEF SUMMARY OF THE INVENTION
Briefly described, in a preferred embodiment, the present invention overcomes the above-mentioned disadvantages and meets the recognized need for such a device by providing, a method and apparatus for a self-contained variable, pitch and/or constant speed propeller including provisions for feathering and reverse pitch operation, wherein no direct contact is required between the fixed engine or airframe and the rotating propeller for effectuation of blade pitch change, therefore eliminating the burdens and complexities generally associated with propeller installation, maintenance and blade pitch change operations.
According to its major aspects and broadly stated, the present invention in its preferred form is a method and apparatus for a self-contained variable pitch and/or constant speed propeller including provisions for feathering and reverse pitch operation, having, in general, a blade control module, command module, power module, and pitch changer, functioning in association with a propeller hub, propeller blades and propeller shaft housing.
More specifically, in the preferred form, power is supplied by a simple permanent magnet alternator arranged such that the magnets are attached to the fixed portion of the engine, gearbox, or airframe and the coils are attached to the propeller hub. The power available from the alternator can be varied by the number and radial location of the coils and magnets utilized. The necessary power for a specific propeller must be sufficient to change the blade pitch at the maximum required rate when operating at a relatively low angular velocity. The required power available from the alternator will be a function of the specific propeller design. The current flow induced in the coils by the rotation of the propeller goes to a conventional power control module in the propeller hub which provides controlled voltage D.C. power available to operate the system. The pitch setting information is supplied by two non-contact position sensors arranged as follows: (1) the detector halves of the sensors are attached to the rotatable propeller hub along a single radial or azimuth, wherein the other portions of the sensors are attached to the fixed airframe or engine; and wherein (2) one of the sensor halves on the fixed airframe or engine serves as the reference sensor, and is not adjustable. The other sensor half on the fixed airframe or engine is adjustable azimuthally and serves as the command sensor.
The signals from the sensors go to the blade control module, an integrated circuit device with simple computing and timing capability.
The output from the sensors is used to determine the current angular velocity, angular accelerati
Edgar Richard A.
Look Edward K.
Myers Joel D.
Myers & Kaplan LLC
Patel Ashish D.
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