Planetary gear train for use with extended length sun in high torque applications

Abstract

A planetary gearbox, also known as an epicyclical gearbox is disclosed herein. The gearbox includes multiple rows of planets and a ring gear. The sun gear is a single unitary structure which simultaneously engages the multiple rows of planets. The system lowers the stress level on torque generating devices incorporating such a gearbox.

Description

BACKGROUND OF THE DISCLOSED TECHNOLOGY

Planetary gears, also known as sun gears and as epicyclic gears, comprise one or more outer gears, or planet gears, revolving about a central, or sun gear. Typically, the planet gears are mounted on a movable carrier or cage or arm which itself may rotate relative to the sun gear. Planetary gears also include the use of an outer ring gear, which meshes with the planet gears.

Planet gears are used in different types of torque generating devices, such as wrenches and gearboxes However, planetary gears existing in the prior art suffer a major disadvantage, in that torque generated by the torque generating device transfers much stress to the gearing system, causing great wear to the gears.

There is a long felt need in the art for a gearing system which reduces stress in the torque generating device and on the gear system included therein.

U.S. Patent Application Publication 2013/0072344 to Volkov et al discloses an epicycle gear with housing and an externally toothed central shaft, such as a sun gear. The planet gears are disposed in rows in corresponding apertures. However, each row of planet gears are not axially offset from each adjacent row of planets.

U.S. Pat. No. 4,964,844 to Bagnall discloses a gearbox arrangement which uses a planetary gear to drive a multi-bladed rotor. Two different gears are used for each rotor. As such, at times the blades, or planets, will be axially offset from each other. However, these planet gears are not within the same ring gear and are not held in an axially offset position by a housing.

China Utility Model Publication 202914647 discloses two rows of planets, arranged around two sun gears and two rings as an input, and additional portions of the gear as an output.

SUMMARY OF THE DISCLOSED TECHNOLOGY

The disclosed technology described herein addresses a need, unfulfilled in the prior art, for providing a planetary gear system, including a single sun gear including external sun-gear teeth, a plurality of planet gears, each including external planet gear teeth, the plurality of planet gears being arranged in at least two rows of planet gears, a circular housing portion having the plurality of planet gears rotatably attached thereto such that the planet gears extend into a hollow interior of the housing, and a ring gear disposed exterior to the circular housing and including internal gear teeth, the external planet gear teeth of each planet gear simultaneously engaging the external sun gear teeth of the sun gear and the internal teeth of the ring gear. Each planet gear simultaneously engages the single sun gear, and further, the ring gear simultaneously engages each planet gear, in embodiments of the disclosed technology_y. a generally circular plane of the housing, and a ring gear disposed exterior to the circular housing and including internal gear teeth, the external planet gear teeth of each planet gear simultaneously engaging the external sun gear teeth of the sun gear and the internal teeth of the ring gear. Each planet gear simultaneously engages the single sun gear, and further, the ring gear simultaneously engages each planet gear, in embodiments of the disclosed technology.

In some embodiments, the planet gears in each row generally form a circle of planet gears in the row. In some embodiments, the planet gears form a general circle of planet gears about the sun gear.

In some embodiments, the planet gears in a first row are arranged in a first cross-shape, and the planet gears in a second row are arranged in a second cross-shape, the first cross-shape and the second cross-shape being rotationally offset from one another.

In some embodiments, the planet gears in different rows are not axially aligned with one another in the carrier.

In some embodiments, the gear system further includes a plurality of bores extending through the carrier, each of the plurality of bores extending through a center of a single one of the planet gears. In some such embodiments, the plurality of bores may have screws or receptacles there-for to attached to a torque generating device.

In accordance with another aspect of the disclosed technology, there is also provided a planetary gear system, including a single sun gear including external sun-gear teeth, a circular carrier portion including a first cross shaped manifold and a second cross shaped manifold, the second cross shaped manifold being rotationally offset from the first cross shaped manifold, a plurality of planet gears, each including external planet gear teeth, some of the plurality of planet gears rotatably attached to the first cross shaped manifold thereby to form a first row of planet gears, and some of the plurality of planet gears rotatably attached to the second cross shaped manifold thereby to form a second row of planet gears, and a ring gear disposed exterior to the circular carrier and including internal gear teeth, the external planet gear teeth of each the planet gear simultaneously engaging the external sun gear teeth of the sun gear and the internal teeth of the ring gear.

In some embodiments, the planet gears in each row are arranged on the cross shaped manifold so as to form a general circle of planet gears in the row.

In some embodiments, the planet gears in the first and second rows form a general circle of planet gears about the sun gear.

In some embodiments, the planet gears in different the rows are not axially aligned with one another.

In some embodiments, the planetary gear system further includes a plurality of bores extending through the carrier, each of the plurality of bores extending through a center of a single one of the planet gears. gcarrier, each of the plurality of bores extending through a center of a single one of the planet gears.

In accordance with another aspect of the disclosed technology, there is also provided a planetary gear system, including a generally circular ring gear having ring-gear teeth formed on an internal surface thereof; single sun gear including external sun-gear teeth, a circular carrier portion disposed within the ring gear, a plurality of planet gears, each including external planet gear teeth, the plurality of planet gears being rotatably attached to the carrier portion and being arranged in at least two rows of planet gear, and a sun gear removably disposed in a center of the carrier portion and including external sun gear teeth, the external planet gear teeth of each the planet gear simultaneously engaging the external sun gear teeth of the sun gear and the internal ring gear teeth of the ring gear.

In some embodiments, the planet gears in each row generally form a circle of planet gears in the row. In some embodiments, the planet gears form a general circle of planet gears about the sun gear.

In some embodiments, the planet gears in a first row are arranged in a first cross-shape, and the planet gears in a second row are arranged in a second cross-shape, the first cross-shape and the second cross-shape being rotationally offset from one another.

In some embodiments, the planet gears in different the rows are not axially aligned with one another in the carrier.

In some embodiments, the gear system further includes a plurality of bores extending through the carrier, each of the plurality of bores extending through a center of a single one of the planet gears.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a planetary gearbox according to the prior art, including a carrier with a single row of planets with a sun gear. carrier with a single row of planets with a sun gear.

FIG. 2 shows a perspective view of a planetary gearbox according to the prior art, including a single row of planets and a ring gear.

FIG. 3 shows a perspective view of an assembled planetary gearbox according to the prior art, including a row of planets, a ring gear, and a sun gear.

FIG. 4 shows a cross section of a planetary gearbox including a single row of planets according to the prior art.

FIG. 5 shows front, side and back views of a planetary gearbox including a single row of planets according to the prior art.

FIG. 6 shows a perspective view of a planetary gearbox, including multiple rows of planets and a sun gear, in an embodiment of the disclosed technology.

FIG. 7 shows a perspective view of a planetary gearbox, including multiple rows of planets, a sun gear, and a ring gear, in an embodiment of the disclosed technology.

FIG. 8 shows a perspective view of an assembled planetary gearbox, including a ring gear, multiple rows of planets, and a sun gear in operational position, in an embodiment of the disclosed technology.

FIG. 9 shows two cross section views of a planetary gearbox including different rows of planets in an embodiment of the disclosed technology

FIG. 10 shows front, side, and back views of a planetary gearbox of the disclosed technology.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE DISCLOSED TECHNOLOGY

The presently disclosed technology is directed towards a planetary gearbox, also known as an epicyclical gearbox, The gearbox includes multiple rows of planets and a ring gear. The sun gear is a single unitary structure which simultaneously engages the multiple rows of planets. The system is designed to lower the stress level on torque generating devices incorporating such a gearbox by shortening the length of each planet. In an epicyclical gear stage the planets react against the ring gear and they are engaged with the rotating sun causing the centers of the planets to orbit around the sun; the centers of the planets are connected axially to the bores of the carrier, causing the carrier to rotate. For a planetary gear train to be efficient, each planet must be rigid enough not to deform while under load. The present invention accomplishes that by splitting the length of the planets into multiple rows for applications where the planet/sun length is required to be large with comparison to their respective diameters.

FIG. 1 shows a perspective view of a planetary gearbox 10 according to the prior art, including a carrier with a single row of planets with a sun gear. The planetary gearbox 10 comprises a sun gear 12 connected to a shaft 13, one set of two or more planets 14, and a carrier 16, sometimes also called a cage, in which the planets 14 are mounted. The external teeth of planets 14 are configured to engage with internal teeth of another gear or carrier portion, for example a ring gear, as shown in FIG. 2. During construction, the sun gear 12 is inserted into carrier 16 at a bore 18 located on a first side of carrier 16, and on a second side thereof the carrier 16 includes a cylindrical arm or shaft 19. At least two circular bores 20 are included in side walls of carrier 16, typically adjacent to, or overlying, planets 14. The sun gear 12 is shown separate from the carrier 16. In other embodiments, three, four, five, six, or eight circular bores may be used.

In use, the planets 14 rotate around the sun gear 12. The sun gear 12 typically provides the input power of the gearbox, which is transformed into output power and is outputted through the shaft 19.

FIG. 2 shows a perspective view of a planetary gearbox according to the prior art, such as planetary gearbox 10 of FIG. 1, including a single row of planets and a ring gear. As seen in FIG. 2, in some embodiments the planetary gearbox of FIG. 1 additionally includes a ring gear 22 disposed around the carrier 16. Ring gear 22 is typically stationary, and includes internal gear teeth 24 which engage the gear teeth of planet gears 14 mounted on carrier 16, such that the planets 14 revolve around ring gear 22. Similarly to FIG. 1, though sun gear 12 is illustrated externally to carrier 16, it is configured to be placed in bore 18 of the carrier 16. As in FIG. 1, four circular bores 20 are located in a wall of carrier 16, their locations generally corresponding to locations of planets 14.

FIG. 3 shows a perspective view of an assembled planetary gearbox according to the prior art, including a row of planets, a ring gear, and a sun gear, such as assembled gearbox 10 of FIGS. 1 and 2. As seen in FIG. 3, when gearbox 10 is assembled, sun gear 12 is inserted in bore 18, such that shaft 13 of sun gear 12 is generally aligned with, and is on the opposite side of carrier 16 to shaft 19.

FIG. 4 shows a cross section of a planetary gearbox including a single row of planets engaging a ring gear according to the prior art, similar to planetary gearbox 10 of FIGS. 1 to 3. As seen in FIG. 4, the teeth 24 of ring gear 22 engage the teeth 26 of the planets 14. Teeth 26 of planets 14 further engage teeth 28 of sun gear 12, disposed in bore 18 in the center of carrier 16. Further, each one of the four circular bores 20 extends through the entire thickness of the wall of carrier 16 and through the center of a single planet 14.

FIG. 5 shows front, side and back views of an assembled planetary gearbox including a single row of planets, a sun gear, and a ring gear, according to the prior art, such as planetary gearbox 10 of FIGS. 1 to 4. The side view shows the ring gear 22 holding carrier 16 with planet gears 14 as well as the sun gear, such that shaft 19 extends out of one side of carrier 16, and sun gear shaft 13 extends out of the other side of carrier 16.

The front view shows the teeth 24 of the ring gear 22, the four circular bores 20 that extend through the walls of the carrier 16, and the shaft 19 located in the center of carrier 16.

The back view shows the ring gear 22 and its teeth 24, and the four circular bores 20 extending through the walls of carrier 16. The circular center bore 18 located in the center of the carrier 16 and used to accommodate sun gear 12 is shown in the back view, as well as the planet teeth 26 engaging teeth 28 of the sun gear 12 in order to transform the input force coming from the sun gear 12 into rotary motion.

FIG. 6 shows a perspective view of a planetary gearbox 110, including multiple rows of planets and a sun gear, in an embodiment of the disclosed technology. The planetary gearbox 110 comprises a sun gear 112 connected to a shaft 113. A first set of planets 114a, arranged in a first row, or layer, and a second set of planets 114b, arranged in a second row, or layer, are disposed within a carrier 116. In the illustrated embodiment, there are four planets 114a in the first set, and four planets 114b in the second set, totaling eight planets. However, any suitable number of planets may be used. In the illustrated embodiment, the planets 114 generally form a circle, and planets 114a are arranged such that they are not aligned with, or concentric to, planets 114b, though in other embodiments planets on different rows may be aligned with one another. External teeth 126 of planets 114 are designed to engage internal teeth of a housing portion or another gear, as described hereinbelow.

During construction, the sun gear 112 is inserted into carrier 116 at a bore 118 located on a first side of carrier 116, and on a second side thereof the carrier 116 includes a cylindrical arm or shaft 119. A plurality of circular bores 120 are included in side walls of carrier 116, typically aligned with and overlying planets 114, such that a single bore 120 corresponds to a single planet 114. As such, the illustrated embodiment shows eight bores, though any other suitable number of bores may be used, provided that the number of bores corresponds to the number of planets. In the illustrated embodiment, the sun gear 112 is shown separate from the carrier 116.

Similarly to the prior art, in use, the planets 114 rotate around the sun gear 112. The sun gear 112 typically provides the input power of the gearbox 110, which is transformed into output power and is outputted through the shaft 119.

The length of components that may be used in a planetary gearbox is mechanically limited. For higher torque capacities, the length of the components must be increased to provide increased engagement of the gear teeth. However, there is a limit to the ratio of planet diameter to planet length, primarily due to the lack of planet support when the planets become too long. As a result, the torque capacity of planetary gearboxes including a single row, or layer, of planets, such as prior art system 10 described in FIGS. 1 to 5 hereinabove, is limited by the relatively short length of the components. By contrast, due to the multiple rows of planets, embodiments of the disclosed technology allow for greater torque capacity of the planetary gearbox than prior art systems, without increasing the length of the planets.

FIG. 7 shows a perspective view of a planetary gearbox, similar to planetary gearbox 110 of FIG. 6, including multiple rows of planets, a sun gear, and a ring gear, in an embodiment of the disclosed technology. As seen in FIG. 7, in some embodiments of the disclosed technology, the planetary gearbox of FIG. 6 additionally includes a ring gear 122 disposed around the carrier 116. Ring gear 122 is typically stationary, and includes internal gear teeth 124 which engage the gear teeth 126 of planet gears 114a and 114b mounted in carrier 116, such that the planets 114 revolve around ring gear 122. Thus, ring gear 122 is sufficiently wide to engage both rows of planets 114a and 114b, or any number of rows of planets used in a specific embodiment. As such, ring gear 122 is relatively wider than the ring gear used in prior art planetary gears, such as ring gear 22 of FIGS. 2 to 5 described hereinabove. As in the description of FIG. 6 hereinabove, planets 114 generally form a circle about sun gear 112, and planets 114a are arranged such that they are not aligned with, or parallel to, planets 114b, though in other embodiments planets on different rows may be aligned with one another.

Similarly to that illustrated in FIG. 6, though sun gear 112 is illustrated externally to carrier 116, it is configured to be placed in bore 118 of the carrier 116. As in FIG. 6, eight circular bores 120 are located in a wall of carrier 116, their locations corresponding to locations of planets 114a and 114b, such that a single bore 120 corresponds to a single planet 114.

FIG. 8 shows a perspective view of an assembled planetary gearbox, such as an assembled gearbox 110 of FIGS. 6 and 7, including a ring gear, multiple rows of planets, and a sun gear in operational position, in an embodiment of the disclosed technology. As seen in FIG. 8, when gearbox 110 is assembled, sun gear 112 is inserted in bore 118, such that shaft 113 of sun gear 112 is generally aligned with, and is on the opposite side of carrier 116 to shaft 119. Similar to the disclosure of FIGS. 6 and 7, gearbox 110 includes a first row of planets 114a and a second row of planets 114b, surrounding sun gear 112. The multiple rows of planets 114 allow the gearbox 110 to provide more torque, additional stability, operate in limited spaces, and enable shorter planet lengths with shorter unsupported lengths of planet shafts.

FIG. 9 shows two cross section views of a planetary gearbox including multiple rows of planets engaging a ring gear in an embodiment of the disclosed technology, similar to planetary gearbox 110 of FIGS. 6 to 8. As seen, a first cross section view labeled ‘A’, is taken along a plane of carrier 116 housing planet gears 114a, whereas a second cross section view labeled ‘B’ is taken along a plane of carrier 116 housing planet gears 114b.

As seen in FIG. 9, the teeth 124 of ring gear 122 engage the teeth 126 of the planets 114a and 114b. Teeth 126 of planets 114 further engage teeth 128 of sun gear 112, disposed in bore 118 in the center of carrier 116. Further, each one of the eight circular bores 120 extends through the entire thickness of the wall of carrier 116 and through the center of a single one of planets 114. As such, bores 120 may be used to connect the planetary gearbox 110 to another tool unit, thereby reducing stress on gearbox 110 and on the other tool unit.

The planets 114a are arranged on a first cross shaped manifold 130a, and the planets 114b are arranged on a second cross shaped manifold 130b, the second cross shaped manifold 130b being rotationally offset relative to the first cross shaped manifold 130a, such that planet gears 114 generally form a circle about sun gear 112 and bore 118 and such that planets 114a do not lie concentric to planets 114b.

FIG. 10 shows front, side, and back views of a planetary gearbox in an embodiment of the disclosed technology, such as planetary gearbox 110 of FIGS. 6 to 9. The side view shows the ring gear 122 holding carrier 116 with planet gears 114 as well as the sun gear such that shaft 119 extends out of one side of carrier 116, and sun gear shaft 113 extends out of the other side of carrier 116.

The front view shows the teeth 124 of the ring gear 122, the eight circular bores 120 arranged in a circle around carrier 116 and extending through the walls of the carrier 116, and the shaft 119 located in the center of carrier 116.

The back view shows the ring gear 122 and its teeth 124, and the eight circular bores 120 extending through the walls of carrier 116. The circular center bore 118 located in the center of the carrier 116 and used to accommodate sun gear 112 is shown in the back view, as well as the teeth 126 of the planets 114 engaging teeth 128 of the sun gear 112 in order to transform the input force coming from the sun gear 112 into rotary motion.

It should further be understood, that the sun gear can be formed from a unitary structure having a continuous elongated length. The planets held in a carrier can each simultaneously engage the sun gear. In turn, each planet, simultaneously engages a ring gear. As such, the multiple planets simultaneously engage both a single sun gear and single ring gear, thereby maximizing torque and efficiency. While the technology has been described with input torque applied to the shaft of the sun gear with reference to a stationary ring gear, thereby causing, based on rotation of the shaft, the sun gear and ring gear to rotate, one having ordinary skill in the art should understand that the input torque can be applied to the ring gear or any other gear described herein This, in turn, causes the rest of the engaged gears to turn.

While the disclosed technology has been taught with specific reference to the above embodiments, a person having ordinary skill in the art will recognize that changes can be made in form and detail without departing from the spirit and the scope of the disclosed technology. The described embodiments are to be considered in all respects only as illustrative and not restrictive. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. Combinations of any of the methods, systems, and devices described herein above are also contemplated and within the scope of the invention.

Claims

1. A planetary gear system, comprising:

a single sun gear including external sun-gear teeth;

a plurality of planet gears, each including external planet gear teeth, said plurality of planet gears being arranged in at least two rows of planet gears, wherein each planet gear simultaneously engages said single sun gear;

a circular carrier portion having said plurality of planet gears rotatably attached thereto such that said planet gears extend into a hollow interior of said carrier as well as outside a generally circular plane of said carrier; and

a ring gear disposed exterior to said circular carrier and including internal gear teeth,

said external planet gear teeth of each said planet gear simultaneously engaging said external sun gear teeth of said sun gear and said internal teeth of said ring gear.

2. The planetary gear system of claim 1, wherein said planet gears in each said row generally form a circle of planet gears in said row.

3. The planetary gear system of claim 1, wherein said planet gears form a general circle of planet gears about said sun gear.

4. The planetary gear system of claim 1, wherein said planet gears in a first said row are arranged in a first cross-shape, and said planet gears in a second said row are arranged in a second cross-shape, said first cross-shape and said second cross-shape being rotationally offset from one another.

5. The planetary gear system of claim 1, wherein said planet gears in different said rows are not axially aligned with one another in said carrier.

6. The planetary gear system of claim 1, further comprising a plurality of bores extending through said carrier, each of said plurality of bores extending through a center of a single one of said planet gears.

7. The planetary gear system of claim 6, wherein said plurality of bores are removably fastened into a torque generating device thereby reducing stress of said torque generating device.

8. A planetary gear system, comprising:

a single sun gear including external sun-gear teeth;

a circular carrier portion comprising a first cross shaped manifold and a second cross shaped manifold, said second cross shaped manifold being rotationally offset from said first cross shaped manifold;

a plurality of planet gears, each including external planet gear teeth, some of said plurality of planet gears rotatably attached to said first cross shaped manifold thereby to form a first row of planet gears, and some of said plurality of planet gears rotatably attached to said second cross shaped manifold thereby to form a second row of planet gears;

a ring gear disposed exterior to said circular carrier and including internal gear teeth,

said external planet gear teeth of each said planet gear simultaneously engaging said external sun gear teeth of said sun gear and said internal teeth of said ring gear.

9. The planetary gear system of claim 8, wherein said planet gears in each said row are arranged on said cross shaped manifold so as to form a general circle of planet gears in said row.

10. The planetary gear system of claim 8, wherein said planet gears in said first and second rows form a general circle of planet gears about said sun gear.

11. The planetary gear system of claim 8, wherein said planet gears in different said rows are not axially aligned with one another.

12. The planetary gear system of claim 8, further comprising a plurality of bores extending through said carrier, each of said plurality of bores extending through a center of a single one of said planet gears.

13. The planetary gear system of claim 12, wherein said plurality of bores are adapted to be attached into a torque generating device.

14. A planetary gear system, comprising:

a generally circular ring gear having ring-gear teeth formed on an internal surface thereof; single sun gear including external sun-gear teeth;

a circular carrier portion disposed within said ring gear;

a plurality of planet gears, each including external planet gear teeth, said plurality of planet gears being rotatably attached to said carrier portion and being arranged in at least two rows of planet gears; and

a sun gear removably disposed in a center of said carrier portion and including external sun gear teeth,

said external planet gear teeth of each said planet gear simultaneously engaging said external sun gear teeth of said sun gear and said internal ring gear teeth of said ring gear.

15. The planetary gear system of claim 14, wherein said planet gears in each said row generally form a circle of planet gears in said row.

16. The planetary gear system of claim 14, wherein said planet gears form a general circle of planet gears about said sun gear.

17. The planetary gear system of claim 14, wherein said planet gears in a first said row are arranged in a first cross-shape, and said planet gears in a second said row are arranged in a second cross-shape, said first cross-shape and said second cross-shape being rotationally offset from one another.

18. The planetary gear system of claim 14, wherein said planet gears in different said rows are not axially aligned with one another in said carrier.

19. The planetary gear system of claim 14, further comprising a plurality of bores extending through said carrier, each of said plurality of bores extending through a center of a single one of said planet gears.