Retaining device for planetary gear shaft of planetary gear set

Abstract

The planetary gear set includes a sun gear; a ring gear; planet gears positioned between the sun gear and the ring gear to rotate around the sun gear; a planet gear carrier; planet gear shafts to which the planet gears are connected to rotate around the planet gear shafts; and retaining pins positioned in the planet gear shafts and the planet gear carrier so as to couple the planet gear shafts to the planet gear carrier.

Description

Technical Field

[0001] The present disclosure relates to a planetary gear set, and more particularly to a method for retaining a planet gear shaft on a planet gear carrier. Background Art

[0002] The planetary gear set includes a sun gear, a ring gear, a plurality of planetary gears positioned between the sun gear and the ring gear to rotate around the sun gear, and a planetary gear carrier coupled to the planetary gears. In some examples, the planetary gear set includes a planetary gear shaft for each planetary gear. The planetary gear shaft is coupled to the planetary gear carrier. Each planetary gear is coupled to a corresponding one of the planetary gear shafts and rotates around it. Summary of the invention

[0003] According to one aspect of the present disclosure, a planetary gear set includes: a central gear that is rotatable about a rotation axis; a ring gear; planetary gears that are located between the central gear and the ring gear to rotate around the central gear, and a planetary gear carrier; a planetary gear shaft to which the planetary gears are connected to rotate around the planetary gear shaft; a retaining pin that is positioned in a fixed arrangement in the planetary gear shaft and the planetary gear carrier to couple the planetary gear shaft to the planetary gear carrier; and a base that is positioned in an inner hole and aligned with the retaining pin so that the retaining pin abuts against the base, thereby preventing the retaining pin from coming out of the fixed arrangement.

[0004] The above and other features will become apparent from the following description and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] DETAILED DESCRIPTION OF THE DRAWINGS Reference is made to the accompanying drawings, in which:

[0006] Figure 1 is a perspective view showing a planetary gear set.

[0007] Figure 2 is an exploded perspective view showing a planetary gear set.

[0008] Figure 3 is along Figure 1 A cross-sectional view taken along line 3-3 of FIG. 1 showing a retaining pin in a fixed arrangement to couple a planet gear shaft to a planet gear carrier of a planetary gear set;

[0009] Figure 4 is a cross-sectional view showing an alternative embodiment; and

[0010] Figure 5 is a cross-sectional view showing another alternative embodiment. DETAILED DESCRIPTION

[0011] Reference Figure 1-3, a planetary gear set 10 is shown. The gear set 10 includes a sun gear 12, a ring gear 14, planet gears 16 (e.g., four) and a planet gear carrier 18. The sun gear 12 is located in an inner bore 19 of the planet gear carrier 18 and is rotatable about a rotation axis 20. The planet gears 16 are located between the sun gear 12 and the ring gear 14 and mesh with one or both of them, and revolve around the sun gear 12. Schematically, the planet gears 16 mesh with the sun gear 12 and the ring gear 14, and are evenly positioned about the axis 20. The planet gears 16 are mounted to the planet gear carrier 18 in a manner that facilitates easy assembly and disassembly.

[0012] The gear set 10 includes two bearings 22a, 22b (e.g., ball bearing type) that position the sun gear 12. The inner bore 19 surrounds the axis 20, and the bearings 22a, 22b surround the axis 20 and are positioned in the inner bore 19, and the bearings 22a, 22b are axially located on both sides of the sun gear 12 relative to the rotation axis 20 in a manner that contacts the sun gear 12. A retaining ring 23 is positioned in an annular groove 24 of the planet gear carrier 18 to hold the bearings 22a, 22b and the sun gear 12 in place axially relative to the axis 20. The bearings 22a, 22b are radially located between the sun gear 12 and the planet gear carrier 18 relative to the axis 20. Schematically, the planet gear carrier 18 is radially located on the bearings 22a, 22b relative to the axis 20.

[0013] The gear set 10 includes two O-rings 25. Each O-ring 25 is located in the inner bore 19 and between the sun gear 12 and the corresponding bearing 22a, 22b. The O-ring 25 is compressible, allowing the sun gear 12 to float slightly (for ease of illustration, the O-ring 25 is shown in a nominal configuration). The O-ring 25 can be made of an elastomeric material.

[0014] The planet gears 16 are rotatably coupled to a planet gear carrier 18. The gear set 10 includes a planet gear shaft 26 for each planet gear 16 (e.g., there are four planet gear shafts 26, one planet gear shaft 26 for each planet gear 16). Each planet gear 16 is coupled to a corresponding planet gear shaft 26 of the gear set 10 for rotation about the planet gear shaft 26. Bearings 28 (e.g., needle bearings) are positioned between the planet gears 16 and the planet gear shafts 26 to allow the planet gears 16 to rotate about the planet gear shafts 26 and the planetary axes of rotation 30 of the planet gear shafts 26. Thrust washers 32 are located on either side of the planet gears 16 and the associated bearings 28, such that the washers 32 are axially located between the corresponding portions of the planet gear carrier 18 and the planet gears 16 and the associated bearings 28.

[0015] Each planet gear shaft 26 is coupled to the planet gear carrier 18 by a corresponding retaining pin 34 of the gear set 10 (e.g., there are four retaining pins 34, one retaining pin 34 for each planet gear shaft 26). The retaining pins 34 are positioned in a fixed arrangement in the planet gear shaft 26 and the planet gear carrier 18 to couple the planet gear shaft 26 to the planet gear carrier 18 against axial and rotational movement relative to the planetary axis of rotation 30. Schematically, a single retaining pin 34 is the only retaining pin that couples the planet gear shaft 26 to the planet gear carrier 18, thereby minimizing the number of parts. More generally, a single retaining pin 34 is the only retaining mechanism that couples the planet gear shaft 26 to the planet gear carrier 18.

[0016] The bearing 22a includes a seat 35. The bearing 22a with the seat 35 is positioned in the inner hole 19 and around the axis 20. The bearing 22a with the seat 35 is positioned to align with the retaining pin 34 so that the retaining pin 34 abuts against the seat 35, thereby preventing the retaining pin 34 from being disengaged from the fixed arrangement, thereby preventing the planetary gear shaft 26 from being disengaged from the planetary gear carrier 18. The bearing 22a includes an outer race 36, and the outer race 36 includes the seat 35. The outer surface of the outer race 36 provides the seat 35.

[0017] The retaining pin 34 is positioned in the hole 37 of the planet gear shaft 26 and the hole 38 of the planet gear carrier 18 to couple the planet gear shaft 26 to the planet gear carrier 18. Each hole 37, 38 extends radially relative to the axis 20, so that the retaining pin 34 extends radially in the hole 37, 38. In this way, the holes 37, 38 are radial holes. Any one of the holes 37, 38 may be referred to as a pin hole in this article.

[0018] The planetary gear carrier 18 is positioned on the bearings 22a, 22b. For example, the planetary gear carrier 18 is positioned on the outer race 36 of the bearings 22a, 22b. The hole 38 of the planetary gear carrier 18 is a through hole. The base 35 of the bearing 22a is radially positioned at the hole 38 to contact the retaining pin 34. The outer race 36 of the bearing 22a covers the hole 38 of the planetary gear carrier 18. The holes 37, 38 and the base 35 of the bearing 22a are radially aligned with each other relative to the rotation axis 20.

[0019] The retaining pin 34 is radially movable within the holes 37, 38 in a fixed arrangement. During operation of the gear set 10, centrifugal force pushes the retaining pin 34 radially outward relative to the axis 20, away from the seat 35 of the bearing 22a, to contact the stop 40. During non-operation of the gear set 10, depending on the position of the planetary gear shaft 26 about the axis 20, gravity may push the retaining pin 34 radially inward relative to the axis 20, so that it contacts the seat 35 of the outer race 36 of the bearing 22a.

[0020] Illustratively, the hole 37 of the planetary gear shaft 26 is a multi-diameter radial through hole. The hole 37 includes: a radial first portion 42 having a first diameter 44; and a radial second portion 46, which is located radially outward from the first portion relative to the axis 20 and has a second diameter 48 that is smaller than the first diameter 44. The retaining pin 34 is positioned in the first portion 42. The second portion 46 is configured to receive a tool 50 (e.g., a screwdriver) indicated by an arrow to remove the retaining pin 34 from the first portion 42 during, for example, disassembly.

[0021] The stopper 40 is located radially between the first portion 42 and the second portion 46 to limit radial outward movement of the retaining pin 34. This radial outward movement may be caused by centrifugal force during operation or gravity during non-operation. The stopper 40 is configured as a shoulder of the hole 37, for example.

[0022] The planet gear shaft 26 includes a verification hole 52. The verification hole 52 intersects with the hole 37 so as to communicate therewith so as to check the retaining pin 34 in the hole 37 through the verification hole 52. Exemplarily, the verification hole 52 is an axial verification hole extending axially from the axial end 54 of the planet gear shaft 26 to the hole 37 of the planet gear shaft 26. The verification hole 52 can be used to verify whether the retaining pin 34 is in the proper position.

[0023] The planetary gear shaft 26 includes a lubricant passage 56. The lubricant passage 56 is provided to deliver lubricant (eg, oil) to the components of the gear set 10. The pin bore 37 is axially located between the lubricant passage 56 and the verification bore 52, for example.

[0024] In one embodiment, the lubricant passage 56 and the hole 37 are separated from each other by the inner wall of the planet gear shaft 26, wherein a plug 58 (e.g., a steel ball) is positioned in the opening 60 of the passage 56 by forming an interference fit 58 with the passage 56. The opening 60 and the passage 56 are formed (e.g., drilled) from the end of the planet gear shaft 26 having the opening 60.

[0025] Reference Figure 4 In another embodiment, the lubricant passage 56 intersects the pin hole 37, and the opening 60 is located beside the pin hole 37. In this case, the lubricant passage 56 can be formed (e.g., drilled) from the side of the planetary gear shaft 26 opposite to the above-mentioned side. In particular, a tool (e.g., a drilling tool) can be inserted through the verification hole 52 and the pin hole 37 to form the lubricant passage 56 in the planetary gear shaft 26. The plug 58 can be positioned in the opening 60 of the passage 56 by forming an interference fit with the passage 56 (implying an interference fit of the plug diameter). In other embodiments, the plug 58 can be omitted, and the retaining pin 34 can be used to at least partially block the opening 60 (some leakage from the lubricant passage 56 through the opening 60 is acceptable).

[0026] Return to reference Figure 3 , for the planetary gear shaft 26, the use of a single retaining pin 34 makes it easy to assemble and disassemble the planetary gear shaft 26 to and from the planetary gear carrier 18. During assembly, the bearing 22b is installed in the inner hole 19 of the planetary gear carrier 18, and the planetary gear 16, the bearing 28, and the washer 32 are installed in the planetary gear receiving space 62 of the planetary gear carrier 18. The planetary gear shaft 26 is inserted into the planetary gear carrier 18, the planetary gear 16, the bearing 28, and the washer 32. Depending on the length of the retaining pin 34, the sun gear 12 can be installed before or after the retaining pin 34 is installed. Exemplarily, given the length of the retaining pin 34, the retaining pin 34 is installed before the sun gear 12 and the bearing 22a are installed. The retaining pin 34 is inserted from the inner hole 19 into the pin holes 37, 38. Then, the sun gear 12 and the bearing 22a are inserted into the inner hole 19, and the bearing 22a provides a seat 35 for the retaining pin 34. In other embodiments, with a shorter retaining pin 34, the sun gear 12 and bearing 22b may be installed in the inner bore 19, followed by inserting the retaining pin 34 into the holes 37, 38, and then installing the bearing 22a. Removal may follow the reverse process. The tool 50 may be inserted into the hole 37 to push the retaining pin 34 out of the holes 37, 38 into the inner bore 19 to remove the retaining pin 34. Using a single retaining pin 34 may avoid the need for multiple tools to assemble and disassemble the planetary gear shaft 26 to and from the planetary gear carrier 18.

[0027] Reference Figure 5 According to another embodiment, the seat 35 can be provided by a sleeve 70. In some examples of the gear set 10, one or both bearings 22a, 22b may not be required to locate the sun gear 12. In the case where the bearing 22a is not required to locate the sun gear 10, the sleeve 70 can replace the bearing 22a to provide a seat 35 for the retaining pin 34. The sleeve 70 can surround the axis 20 and include an annular outer surface that includes the seat 35. The sleeve 70 can be positioned in the inner bore 19 to contact the planet gear carrier 18 at the hole 38. The sleeve 70 can cover or partially cover the hole 38 to achieve contact between the seat 35 and the retaining pin 34.

[0028] The gear set 10 can be used in a variety of situations. For example, the gear set 10 can be used in an axle (not shown) of a vehicle. The vehicle can be, for example, a construction machine (e.g., a four-wheel drive loader), a forestry machine, or an agricultural machine, to name a few examples.

[0029] Although example embodiments of the present disclosure are described above, these descriptions should not be viewed in a limiting sense. Rather, other changes and modifications may be made without departing from the scope and spirit of the present disclosure as defined in the appended claims.

Claims

1. A planetary gear set, comprising: a central gear rotatable about an axis of rotation; Ring gear; Planetary gears, which are located between the sun gear and the ring gear to rotate around the sun gear, a planetary gear carrier including an inner bore surrounding an axis of rotation; a planetary gear shaft to which the planetary gears are coupled to rotate about the planetary gear shaft; retaining pins positioned in a fixed arrangement in the planet gear shaft and the planet gear carrier to couple the planet gear shaft to the planet gear carrier; a seat positioned in the inner bore and aligned with the retaining pin so that the retaining pin abuts against the seat, thereby preventing the retaining pin from being dislodged from the securing arrangement; and a bearing located in the inner bore and between the sun gear and the planetary gear carrier, wherein the bearing includes the base, and The retaining pins are positioned in the radial holes of the planetary gear shafts and the radial through holes of the planetary gear carrier, and the radial holes of the planetary gear shafts, the radial through holes of the planetary gear carrier and the base are radially aligned with each other relative to the rotation axis.

2. The planetary gear set according to claim 1, wherein: The bearing includes an outer race, and the outer race includes the seat.

3. The planetary gear set according to claim 1, wherein: The retaining pin seats on the base.

4. The planetary gear set according to claim 1, wherein: The base is radially positioned at the radial through hole of the planetary gear carrier.

5. The planetary gear set according to claim 1, wherein: The radial hole of the planetary gear shaft is a multi-diameter radial through hole, which includes a radial first portion having a first diameter; and a radial second portion, which is positioned radially outward from the radial first portion and has a second diameter smaller than the first diameter, the retaining pin is located in the radial first portion, and the radial second portion is configured to receive a tool to remove the retaining pin from the radial first portion.

6. The planetary gear set according to claim 5, wherein: The radial through hole of the planet gear shaft includes a shoulder between the radial first portion and the radial second portion to limit radial outward movement of the retaining pin.

7. The planetary gear set according to claim 1, wherein: The planet gear shaft includes an axial verification hole extending axially from an axial end of the planet gear shaft to a radial hole of the planet gear shaft to check a retaining pin in the radial hole of the planet gear shaft via the axial verification hole.

8. The planetary gear set according to claim 1, wherein: The planetary gear shaft includes a multi-diameter bore including a first portion having a first diameter and a second portion having a second diameter smaller than the first diameter, a retaining pin is located in the first portion, and the second portion is configured to receive a tool to remove the retaining pin from the first portion.

9. The planetary gear set according to claim 8, wherein: The multi-diameter bore includes a stopper positioned radially between the first portion and the second portion to limit radial outward movement of the retaining pin.

10. The planetary gear set according to claim 8, wherein: The planetary gear shaft includes a verification hole communicating with the multi-diameter hole to check the retaining pin in the multi-diameter hole via the verification hole.

11. The planetary gear set according to claim 1, wherein: The planetary gear shaft includes: a pin hole in which a retaining pin is positioned; and a verification hole intersecting the pin hole for checking the retaining pin in the pin hole.

12. The planetary gear set according to claim 11, wherein: The planet gear shaft includes a lubricant passage, and the pin hole is located axially between the proof hole and the lubricant passage.

13. The planetary gear set according to claim 1, wherein: The planet gear shaft includes a lubricant passage and a bore in which the retaining pin is located and which intersects the lubricant passage.

14. The planetary gear set according to claim 1, wherein: The retaining pin is the only retaining pin that couples the planet gear shaft to the planet gear carrier.

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