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"Control Moment Gyroscopes Including Torsionally-Stiff Spoked Rotors and Methods for the Manufacture Thereof" in Patent Application Approval Process

February 19, 2014

By a News Reporter-Staff News Editor at Defense & Aerospace Week -- A patent application by the inventors Davis, Porter (Phoenix, AZ); Johnson, Theodis (Litchfield Park, AZ); Stevens, Carlos J. (Peoria, AZ), filed on May 21, 2012, was made available online on February 6, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application is assigned to Honeywell International Inc.

The following quote was obtained by the news editors from the background information supplied by the inventors: "Control moment gyroscopes (CMGs) are commonly employed in satellite attitude control systems. A generalized CMG may include a main CMG housing and an inner gimbal assembly (IGA), which is mounted within the main CMG housing for rotation about a gimbal axis. The IGA includes, amongst other components, a rotor assembly, at least one spin motor, and a rotor support structure. In one known design commonly referred to as a 'shell rotor architecture' or, more simply, a 'shell rotor,' the rotor assembly includes an annular rotor rim disposed between first and second hemi-spherical rotor shell pieces. The rotor rim is welded to the first and second rotor shell pieces along first and second circumferential rim-shell weld joints, respectively. Collectively, the rotor rim, the first rotor shell piece, and the second rotor shell piece form a generally spherical body having a central channel through which a rotor shaft extends. During operation, the spin motor rotates the rotor assembly about a spin axis at a relatively high rate of speed. The IGA is, in turn, selectively rotated about the gimbal axis, which is generally perpendicular to the rotor spin axis, by an actuator (e.g., a torque module assembly) mounted within the main CMG housing. When the IGA is 'gimbaled' in this manner, a controlled torque is generated about an output axis normal to the spin and gimbal axes due to momentum transfer of the rotor assembly. This gyroscopic torque is imparted to the host satellite through a CMG mount interface, such as an annular flange bolted to the exterior of the satellite. By selectively rotating the IGA about the gimbal axis, the satellite's attitude may be adjusted and re-adjusted, as needed, in a highly controlled manner

"CMG shell rotors of the type described above have been developed and commercially implemented with considerable success by the assignee of the present Application, Honeywell International Inc. In general, CMG shell rotors provide superior performance characteristics as compared to other conventionally-known CMG rotors, including superior momentum-per-weight ratios and relatively high operational speed limits, as well as high angular stiffness. However, further improvements in momentum-per-weight ratios, speed capabilities, and other measures of CMG performance (e.g., operational lifespan) are still desirable. Moreover, as a notable disadvantage, the manufacturing schedule and costs associated with manufacture of CMGs having shell rotor-based architectures tend to be substantial. It is not uncommon for commercial production of a shell rotor to cost upwards of several hundred thousand U.S. dollars and to require over one year to complete.

"It is thus desirable to provide CMGs including advanced rotors having improved performance characteristics (e.g., increased momentum-per-weight ratios, higher speed limits, longer operational lifespans, and so on) as compared to shell rotor assemblies and other conventionally-known CMG rotor assemblies. Ideally, embodiments of such a CMG, and specifically embodiments of the advanced rotor included within the CMG, would be amenable to production utilizing cost effective and time efficient manufacturing processes. It would also be desirable to provide manufacturing processes for producing CMGs including such high performance rotors. Other desirable features and characteristics of the present invention will become apparent from the subsequent Detailed Description and the appended claims, taken in conjunction with the accompanying drawings and this Background."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "Embodiments of control moment gyroscopes (CMGs) are provided. In one embodiment, a CMG includes a stator housing, an inner gimbal assembly (IGA), and a torque motor coupled to the stator housing and configured to rotate the IGA housing about a gimbal axis to selectively generate a desired output torque during operation of the CMG. The IGA includes, in turn, an IGA housing rotatably coupled to the stator housing, a monolithic CMG rotor rotatably mounted to the IGA housing, and a spin motor coupled to the IGA housing and configured to rotate the monolithic CMG rotor about a spin axis.

"Methods for manufacturing a control moment gyroscope (CMG) are further provided. In one embodiment, the method includes the steps of producing a one piece rotor preform; machining the one piece rotor preform to define a monolithic CMG rotor; and installing the monolithic CMG rotor within an inner gimbal assembly (IGA), which includes an IGA housing and a spin motor configured to rotate the monolithic CMG rotor relative to the IGA housing about a spin axis. The IGA is then mounted to a stator assembly including a stator assembly housing and a torque motor configured to selectively rotate the IGA about a gimbal axis to selectively generate a desired output torque during operation of the CMG.


"At least one example of the present invention will hereinafter be described in conjunction with the following figures, wherein like numerals denote like elements, and:

"FIG. 1 is cross-sectional view of a control moment gyroscope including a high performance monolithic CMG rotor illustrated in accordance with an exemplary embodiment of the present invention;

"FIGS. 2 and 3 are isometric and top views, respectively, of the exemplary monolithic CMG rotor shown in FIG. 1;

"FIG. 4 is a cross-sectional view of a portion of the exemplary monolithic CMG rotor shown in FIGS. 1-3, as taken along line 4-4 in FIG. 3; and

"FIG. 5 is a flowchart illustrating an exemplary method for manufacturing a control moment gyroscope including a monolithic CMG rotor, such as CMG rotor shown in FIGS. 1-4.

"For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction. Elements in the drawings figures are not necessarily drawn to scale. For example, the dimensions of some of the elements or regions in the figures may be exaggerated relative to other elements or regions to help improve understanding of embodiments of the invention. Descriptions and illustrations of well-known features and techniques may be omitted to avoid unnecessarily obscuring the invention."

URL and more information on this patent application, see: Davis, Porter; Johnson, Theodis; Stevens, Carlos J. Control Moment Gyroscopes Including Torsionally-Stiff Spoked Rotors and Methods for the Manufacture Thereof. Filed May 21, 2012 and posted February 6, 2014. Patent URL:

Keywords for this news article include: Honeywell International Inc, Aerospace and Defense Companies.

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Source: Defense & Aerospace Week

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