Abstract
A slew drive includes a housing, a worm shaft having a worm thread carried within the housing for rotational movement, and a torque tube having an outer diameter and a central socket. The torque tube is carried by the housing for rotational movement perpendicularly to the worm shaft and worm thread. A ring gear section having teeth, is carried by the torque tube so that the teeth extend beyond the outer diameter of the torque tube and engage the worm threads. Rotation of the worm shaft rotates the worm threads engaging the teeth of the ring gear section, thereby rotating the ring gear section which rotates the torque tube relative the housing.
Claims
1. A slew drive comprising: a housing; a worm shaft having a worm thread carried within the housing; a torque tube having an outer diameter, the torque tube carried by the housing; and a ring gear section having teeth, the ring gear section carried by the torque tube with the teeth extending beyond the outer diameter thereof and engaging the worm thread.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The foregoing and further and more specific objects and advantages of the invention will become readily apparent to those skilled in the art from the following detailed description of a preferred embodiment thereof, taken in conjunction with the drawings in which:
[0016] FIG. 1 is a perspective side view of a slew drive according to the present invention;
[0017] FIG. 2 is a sectional side of the slew drive of FIG. 1;
[0018] FIG. 3 is a perspective side view of the housing for the slew drive gearbox of FIG. 1;
[0019] FIG. 4 is a perspective side view of the torque tube of the slew drive gearbox of FIG. 1;
[0020] FIG. 5 is a perspective side view of the torque tube of the slew drive gearbox of FIG. 1 with bearing members;
[0021] FIG. 6 is a perspective side view of the torque tube of the slew drive gearbox of FIG. 1 with sealing members;
[0022] FIG. 7 is a partial perspective view of the slew drive with the housing removed; and
[0023] FIG. 8 is a perspective view of the back side of the housing cover.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0024] Turning now to the drawings in which like reference characters indicate corresponding elements throughout the several views, attention is directed to FIGS. 1 and 2 which illustrate a slew drive generally designated 10, according to the present invention. Slew drive 10 includes a gearbox 11 with a housing 12 having a tubular portion 14 and an annular portion 16. With additional reference to FIG. 3, annular portion 16 defines an annular volume 18 encircling a central aperture 20. Tubular portion 14 is coupled to annular portion 16 and defines a volume 22 having a longitudinal axis designated A. Longitudinal axis A forms a tangent to an outer diameter of annular portion 16. Annular volume 18 and volume 22 are in communication with volume 22 overlapping annular volume 18 as a chord with respect to the outer diameter of annular portion 16.
[0025] Still referring to FIGS. 1 and 2, slew drive 10 further includes a drive motor 25 coupled to tubular portion 14 of housing 12. Drive motor 25 is coupled to a worm shaft 24 carrying an hourglass shaped worm thread 26, by a planetary gear assembly 28. Planetary gear assembly 28 is not described or shown in detail, as these assemblies are well known in the art. Worm thread 26 is carried within volume 22 of tubular portion 14 of housing 12, and extends through annular portion 16 at the chord defined previously. Drive motor 25 drives worm thread 26 having a portion of worm thread 26 extending into annular volume 18. Annular portion 16 of housing 12 carries a torque tube 30 and a ring gear section 32. It will be understood that while an hourglass shaped worm thread 26 is preferred, a conventionally shaped worm thread can be employed. Also, while a drive motor 25 is carried by the housing in the preferred embodiment, it will be understood that when multiple slewing drives are employed, the slewing drives can be driven with a series of slave shafts from a master drive motor without using a motor on each individual slewing drive.
[0026] With brief reference to FIGS. 4-6, FIG. 4 illustrates torque tube 30. Torque tube 30 includes an annular body 34 having opposed ends 35 and 36. Each end 35 and 36 includes an annular inset surface 38 formed at each end 35 and 36, and an annular extension 39 extending radially outwardly from body 34 and spaced apart from each end 35 and 36. Torque tube 30 defines central socket 40. A tab 42 extends from a portion of annular extension 39 at end 36. Ring gear section 32 is fixedly attached directly to tab 42 so as to be positioned generally centrally between ends 35 and 36. Ring gear section 32 can be directly machined into tab 42 or attached by fastening members such as pins, screws, bolts and the like, or permanent fasteners such as welding, adhesives and the like. It will be understood that ring gear section 32 is attached so that teeth of ring gear section 32 extend radially outwardly past tab 42. Here it should be noted that a ring gear has a full 360° circumference. Ring gear segment 32 of the present invention is a section of a ring gear less than 360°. In the preferred embodiment, a ring gear is divided into 2-4 segments for use. Thus the preferred segments are 90°, 120° and 180°, but can be anything less than 360°.
[0027] Turning specifically to FIG. 5, a bearing element 43 is position over each end 35 and 36, abutting annular extension 39, forming bearing surfaces 44. Bearing element 43 can be substantially any sort of bearing assembly such as ball bearing, low friction surfaces and the like. The type of bearing is only important as to allow rotation of torque tube 30 freely within annular portion 16. FIG. 6 illustrates torque tube 30 having a seal member 46 carried at each end 35 and 36 seated in annular inset surface 38.
[0028] Turning now to FIG. 7, torque tube 30 is carried by housing 12 so as to center ring gear section 32 within the overlap of volumes 18 and 22 (chord) and in engagement with worm thread 26. In this manner, as drive motor 25 drives worm shaft 24 in a first direction, ring gear section 32 is driven in a first direction with a corresponding rotation of torque tube 30 in the first direction. When drive motor 25 is reversed and drives the worm shaft in a second direction, ring gear section 32 is driven in a second direction with a corresponding rotation of torque tube 30 in the second direction. In this manner, when in use, housing 12 is installed as an immovable fixture. The centrally located torque tube can then be rotated relative housing 12.
[0029] Turning to FIG. 8, housing 12 is sealed by housing cover 50. An inner surface of cover 50 includes an annular extension 52 extending perpendicularly inwardly from an inner edge 53 defining aperture 20, and an annular extension 55 extending perpendicularly inwardly from the inner surface of cover 50 intermediate inner edge 53 and an outer edge 58. When positioned on housing 12, annular extension 52 engages seal member 46, and bearing member 43, effectively sealing housing 12 and permitting rotation of torque tube 30 with respect to housing 12 and cover 50. Annular extension 55 engages and seals against housing 12.
[0030] Various changes and modifications to the embodiments herein chosen for purposes of illustration will readily occur to those skilled in the art. To the extent that such modifications and variations do not depart from the spirit of the invention, they are intended to be included within the scope thereof, which is assessed only by a fair interpretation of the following claims.
