Planetary gear transmission systems or components – Planetary gearing or element
Reexamination Certificate
2001-03-02
2003-04-15
Butler, Douglas C. (Department: 3683)
Planetary gear transmission systems or components
Planetary gearing or element
C074S395000, C074S640000, C056S012700, C172S013000, C464S160000, C242S564100, C242S570000, C030S276000
Reexamination Certificate
active
06547689
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to controlling the relative angular relationship between two elements in a rotating system by changing the relationship between two elements in a related non-rotating system, such that the relative angular relationship between the two elements in the rotating system may easily be altered while the system rotates. More specifically, the present invention provides the ability to either incrementally or continuously alter the angular relationship between two parallel output shafts by introducing a specified angular motion change (angular displacement). Essentially, the two output shafts will, when left alone, rotate together at the same speed, but with the present invention, a user may introduce an angular motion change while the shafts continue to rotate, advancing one shaft's angular position with respect to the other shaft, using a control mechanism in a static reference frame; once the user stops introducing an angular motion change, the two shafts will again rotate together at the same speed, although the angular displacement introduced will remain. In the prior art, there were two techniques for accomplishing this goal: 1) inducing lateral motion in a shaft at the center of rotation of the system, with said motion parallel and congruent to the center of rotation, and then translating that motion into the rotating system using a rotating disk sliding through bearings on levers fixed to the rotating system, or 2) varying the pressure in a hydraulic system, with said hydraulic system translated into the rotating system through a rotating seal, such that the pressure is then utilized to move an element or elements in the rotating system.
There are, however, problems inherent in these previous techniques which limit their effectiveness. Specifically, devices which use these techniques have inherently high wear factors and/or are subject to high manufacturing and maintenance costs because of the close tolerances required and the high stresses placed upon the individual components of the devices. Additionally, as these devices wear, they tend to become more unstable. The rotating disk used in the first technique described above must be able to handle all of the torque induced through the system. Because of the high relative motion of the disk to the rotating system, the rate of wear will be high and, with wear, the system will tend to oscillate. And, the hydraulic-based systems described above are inherently unstable since they do not consist of a direct mechanical coupling. Minute variations in any part of the system will impact the pressure within the hydraulic fluid and will alter the position of the driven elements, with this altering of position then changing the pressure in the hydraulic fluid to initiate positive feedback and cause, or perpetuate, an oscillation.
The present invention overcomes these problems because it employs a direct mechanical coupling which allows for control of the relative angular position of two elements in the rotating system, while such control is induced in or between two static elements outside of the rotating system. Since the present invention uses gears (with meshing teeth) for a direct mechanical coupling, the forces are spread effectively throughout the device, reducing both wear and oscillation concerns.
SUMMARY OF THE INVENTION
The Angular Motion Translator (“AMT”) consists conceptually of two inertial frames: a static reference frame, which is static relative to the observer, and a rotating frame, which rotates about an axis with respect to the static reference frame and the observer. The AMT can be used to translate an angular relationship between two elements contained within the static reference frame into a proportional angular relationship between two elements contained within the rotating frame. More specifically, an angular (rotational) displacement of one of the elements in the static reference frame with respect to the other element in the static reference frame will result in a proportional angular (rotational) displacement of one of the elements in the rotating frame with respect to the other element in the rotating frame, allowing a user of the AMT to easily alter the angular relationship between the two elements in the rotating frame.
The physical embodiments of the AMT are comprised of two linked, identical planetary gear sets. Each planetary gear set is comprised of a sun gear, a planetary gear array (further comprised of one or more planet gears and a planetary carrier which links the planet gears together and which fixes their orbit around the sun gear and the central axis of the planetary gear set), and an annular gear. In such planetary gear sets, the sun gear is located at the center (on the central axis of the planetary gear set), the planet gears rotate around the outside of the sun gear in orbit (with the teeth of each planet gear meshing with the teeth of the sun gear, forming a mechanical coupling), the planetary carrier links the axis of rotation of each of the planet gears and holds the planet gears together in orbit about the sun gear (such that the planetary gear array rotates as a unit), and the annular gear encompasses the whole (with the teeth of the planet gears meshing with the teeth of the annular gear, forming a mechanical coupling).
In the AMT, the two identical planetary gear sets face one another as mirror images. One of the elements of the first planetary gear set is held static, and the identical, matching element in the second planetary gear set is also held static, although the angular relationship between them may be changed. These two elements are in the static reference frame. A different element of the first planetary gear set is rigidly attached to the input shaft, with the input shaft passing through the entire AMT along the center axis (passing through the second planetary gear set without interacting with the second planetary gear set) and emerging as the inner output shaft, and the identical, matching element in the second planetary gear set is rigidly attached to the outer output shaft, which is hollow so that it does not interact with the inner output shaft. The inner output shaft and the outer output shaft are the two elements in the rotating frame. Finally, the remaining elements in both of the planetary gear sets are rigidly linked together so that they rotate as one unit. In this configuration, a change in the angular relationship between the two elements in the static reference frame produces a proportional change in the angular relationship between the two elements in the rotating frame.
So in static mode, when the input shaft rotates to provide driving power, both the inner output shaft (which is essentially a continuation of the input shaft) and the outer output shaft will rotate at the same angular speed (i.e. there will be no angular displacement). If, however, one of the elements which is being held static is rotated with respect to the other element which is being held static in the other planetary gear set, this introduces an angular displacement (either adding or subtracting a proportion of the amount of rotation between the two static elements in the static reference frame to the input rotation, resulting in a change to the outer output shaft rotation). Thus, the angular relationship between the inner output shaft and the outer output shaft may be altered proportionately by rotating one of the static elements with respect to the other.
Although the two planetary gear sets could be connected in any number of ways (so long as identical, matching elements in each planetary gear set are held static; another element in the first planetary gear set is rigidly connected to its sister, identical, matching element in the second planetary gear set; the remaining elements are connected to either the input shaft and the inner output shaft or the outer output shaft respectively; and the matching gears of each of the planetary gear sets are identical in size and number of teeth), there are two preferred embodiments wh
Butler Douglas C.
Phelps Dunbar L.L.P.
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