BACKGROUND OF THE INVENTION
This application relates to improvements in an output seal for use in a gearbox.
Gearboxes are known, and typically include an input shaft driving an output shaft through a plurality of gears. The gears may provide a speed change from the input shaft to the output shaft, or any number of other functions, such as driving a plurality of components from a single input. In one known gearbox, two gearbox housings abut each other, and receive oil for lubricating the gears. A seal located at the bottom of the housing has typically included a rotating ring which rotates with a shaft extending through a bore in the housing. A stationary seal sits within the housing and has a face in abutting engagement with the rotating ring to provide a seal, preventing lubricant from leaking through the bore of the gearbox.
The prior art has any number of different seal designs, however, it is somewhat challenging to provide a simple sealing system that is mechanically robust, adequately prevents leakage and offers a reliable and predictable life expectancy.
SUMMARY OF THE INVENTION
A seal assembly for use in a gearbox has a rotating ring to be secured to a shaft, and having a contact face. The contact face abuts a stationary seal. The stationary seal has a retainer with a channel extending to a bottom. A floating seal portion is positioned within the retainer and a spring is positioned within the channel and inward of an inner end of the floating seal portion, and biasing the floating seal portion outwardly. There is an inner bore of the retainer which is spaced from an outer periphery of the floating seal portion. One of the inner bore and the outer periphery has a plurality of radially located pins. The other of the inner bore and the outer periphery is formed with the plurality of recesses. The pins are received in the recesses, to prevent rotation of the floating seal portion within the retainer.
These and other features may be best understood from the following drawings and specification.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a gearbox.
FIG. 2 shows a gearbox housing and a seal.
FIG. 3 is a cross-section of a seal.
FIG. 4 is a top view of the seal.
FIG. 5 shows a spring incorporated into the seal.
FIG. 6 shows a rotating ring.
FIG. 7 is a top view of an alternative seal embodiment.
FIG. 8 shows a top of an alternative floating seal.
FIG. 9 shows a bottom of the alternative floating seal.
FIG. 10 shows a cross section of the alternative floating seal.
FIG. 11 shows a cross section of a seal with the alternative floating seal.
DETAILED DESCRIPTION
As shown in FIG. 1, a gearbox 20 incorporates an upper housing 24 and a lower housing 22. An oil level 23 is typically provided within the lower housing 22.
FIG. 2 is an exploded view showing the lower gearbox housing 22. As shown, a bore 21 extends outwardly of the housing. A seal assembly 19, incorporating an o-ring 40, a rotating ring 28, and a stationary seal portion 26, is received in the bore 21. The rotating ring 28 rotates with a shaft 30 which extends into the gear housing 22 and is connected to gears 31, which are shown schematically.
The purpose of the combined seal 19 is to prevent leakage of lubricant through the bore 21 while allowing the shaft 30 to rotate.
FIG. 3 is a cross-section through the combined seal 19. As shown, a retainer 32 incorporates a plurality of pins 42 (see FIG. 4 also) which extend into the recesses 44 in a floating seal portion 36. The o-ring 40 is captured between a bore 301 located on retainer 32, and a counterbore 300 located on the floating seal portion 36. A channel 38 within the retainer 32 receives a spring 50, which is shown schematically in this Figure.
FIG. 4 shows that there are pins 42 extending into recesses 44. The pins 42 prevent the floating seal portion 36 from rotating within the retainer 32. The pins 42 are disclosed as separate elements from the retainer 32, but can also be formed integrally. However, there is clearance between the pins 42 and the recesses 44 that will allow the floating seal portion 36 to move freely in a vertical direction, and to articulate about an axial centerline X, for limited angles. This allows floating seal portion 36 to move and conform to a mating rotating ring contact surface, as will be explained below. FIG. 4 shows two pins 42 being utilized. Alternatively, FIG. 7 shows three pins 42 being utilized. Of course, more or less pins 42 could be utilized.
FIG. 5 shows that a single spring 50 is formed by a plurality of webs 52. The prior art generally included a plurality of springs biasing a floating seal portion towards a rotating ring. The use of a single spring simplifies the assembly and provides a uniform mechanical load distribution to the floating seal. One example spring is available from Smalley Steel Ring Co. of Lake Zurich, Ill. Of course, other springs can be utilized.
FIG. 3 shows a surface or sealing nose 59 formed at a fixed distance relative to inner peripheral surface 101 of the outer seal portion 58. Locating the sealing nose 59 at a specific location improves the operation of the seal, and provides an optimal pressure balance ratio between a hydraulic loading area and a sealing interface area.
FIG. 3 shows recesses 61 formed radially inward and outward of the sealing nose 59. Sealing nose 59 contacts a contact face 80 of the rotating ring 28.
The floating seal portion 36, and the rotating ring 28, may be generally formed of a silicon carbide material. Of course, there may be other materials included within each of these components. As one example only, the contact surface face 80 of the rotating ring 28 is formed with a hardened material, as shown in FIG. 6.
FIGS. 8-10 show one example floating seal 36 with a plurality of cooling holes 60 defined therein. The example holes 60 are defined from the outer seal portion 58 and extend at a non-parallel angle with respect to central axis A to a lower annulus 62 that supplies fluid to the holes 60. The example holes 60 are angled such that the openings at the outer seal portion 58 are closer to the central axis than the openings at the lower annulus 62. A pressure differential exists between the entry and exit of each hole 60 which promotes flow and subsequent heat removal from the substrate. FIG. 11 shows an example stationary seal 26 having a floating seal 36 with a plurality of cooling holes 60.
FIG. 6 shows a detail of the rotating ring 28. A contact surface 80 is provided with a diamond material, which will decrease a co-efficient of friction, and increases surface hardness for the surface which is in contact with the sealing nose 59. In one embodiment, a polycrystalline structure diamond material is applied to the face. One acceptable material is available from Advanced Diamond Technologies of Romeoville, Ill.
Patent Application
20140203513
