GEARBOX

Description

BACKGROUND

[0001] The present invention relates to a gearbox, and more particularly, to a system to prevent oil leakage by diverting oil from a shaft penetration back into the gear casing.

[0002] Gearing is often used between a driver and a driven component to, for example, change the speed or torque of the driver to a speed or torque needed for the driven component. For example, gearing can be used between a motor and a fan to drive the fan at a different speed than the motor output.

[0003] Such gearing is incorporated into a gearbox and is often contained in a gear casing or housing. The internal components of a gearbox such as gears as bearings require lubrication to reduce friction, wear, and heat. The lubricating medium, typically gear oil, is often circulated within the housing by either forced or passive methods, such as an oil pump or splash lubrication, respectively.

[0004] In most gear systems or gearboxes, there are penetrations or openings in the housings through which input and / or output shafts traverse. In order to prevent oil from leaking through the rotating shaft penetrations, various sealing mechanisms, such as radial lip seals, mechanical seals or non-contacting bearing isolators are used at the penetration. However, radial lip seals and mechanical seals require direct contact with the rotating shaft, resulting in a wear item that often leaks and requires frequent replacement. While non-contacting bearing isolators do not wear, they often leak when used in splash lubrication applications. This is especially true when the gear casing is oriented such that a shaft utilizing a non-contact bearing isolator is oriented in a horizonal plane.

[0005] One way to address oil leakage issues with non-contacting bearing isolator is to contain or "catch" any oil that leaks from the shaft penetration. This can result in, among other things, environmental contamination, waste of lubricant, and catastrophic failure from loss of oil. Another way in which to address oil leakage is to use external systems, for example, tubing, to collect the oil and redirect it to an auxiliary or main oil reservoir. CN104165209A discloses a gear box comprising a box body, an input shaft, an input bevel gear, an output bevel gear and an output shaft, wherein part of the box is provided with a forced lubrication oil inlet and an oil return opening.

[0006] Accordingly, there is a need for a system to prevent oil from leaking through rotating shaft penetrations in gear casings that utilize non-contacting bearing isolators. Desirably, such a system is a passive system. More desirably still, such a system reduces contamination and waste, diverting the lubricating oil back into the gearbox.SUMMARY

[0007] According to the present invention, there is provided a gearbox as defined in claim 1. The gear box includes a main housing carrying an input shaft and an output shaft. A carrier generally serves as secondary housing that supports a shaft assembly and is mounted to the main housing via, for example, a bolted connection. The carrier is mounted to the main housing and has a bore through which the input or output shaft extends. An isolator plate is mounted to the carrier and has a bore aligned with the carrier bore through which the input or output shaft extends. An isolator is mounted to the isolator plate and has a bore aligned with the isolator plate bore, through which the input or output shaft extends. The gearbox can include intermediate stages of gearing that do not require external penetrations.

[0008] The carrier includes an oil collection well spaced from the shaft bore and an oil return channel in fluid communication with the oil collection well and extending through the carrier to the main housing.

[0009] The isolator plate includes an interior surface and an oil passage formed therein extends from the interior surface to the oil collection well, and is in fluid communication with the main housing via the oil collection well and the oil return channel. Fluid at the interior surface of the isolation dam is drawn into the main housing via the primary oil passage, the oil collection well and the oil return channel.

[0010] In an embodiment, the oil passage is a radially extending passage formed in the isolator plate. The isolator plate can include a projection such that the oil passage extends along the projection. In such an embodiment, the projection can align with the oil collection well of the carrier.

[0011] In an embodiment, the carrier includes a projection containing the oil collection well, which is aligned with the isolator plate projection, providing continuity with both isolator plate oil passages. In another embodiment, the oil return channel in the carrier is spaced from a bottom of the oil collection well. In further embodiments, the oil return channel can be oriented parallel to or askew the bore. Further advantageous embodiments of the invention are laid down in the dependent claims.

[0012] Further understanding of the present invention can be obtained by reference to the following detailed description in conjunction with the associated drawings, which are described briefly below.DESCRIPTION OF THE DRAWINGS

[0013] Various embodiments of a gearbox according to the invention are disclosed and are not limited by the figures of the accompanying drawings, in which like references may indicate similar elements and in which: FIGS. 1A and 1B isometric and front views of an example of the claimed gearbox; FIG. 2 is an isometric view of a carrier, an isolator plate and isolator, and an input shaft extending through the isolator, forming part of the claimed gearbox; FIG. 3 is a side view of the carrier, isolator plate, isolator, and shaft assembly of FIG. 2; FIG. 4 is a view similar to FIG. 2 with the shaft assembly removed for ease of viewing; FIG. 5 is an isometric view of the isolator plate removed from the carrier; FIG. 6 is a cross-sectional view of the isolator plate; FIG. 7 is a view similar to FIG. 4 with the isolator plate and isolator removed for ease of viewing; FIG. 8 is a sectional rendering of the carrier, shown with an isolator plate and isolator, and shaft assembly extending through the isolator; and FIG. 9 is a sectional rendering of the horizontal carrier. DETAILED DESCRIPTION

[0014] While the present invention is susceptible of embodiments in various forms, there is shown in the drawings and will hereinafter be described a presently preferred embodiment with the understanding that the present disclosure is to be considered an exemplification and is not intended to limit the disclosure to the specific embodiment illustrated.

[0015] A novel apparatus or system is disclosed to prevent or reduce oil leakage from a gearbox 12 by diverting the oil within the gearbox 12 from areas of the main housing 16 or secondary housing 26 that include penetrations, back into the main housing reservoir. FIGS. 1A and 1B illustrate one example of a gear casing 16 having a system 10 to prevent or reduce oil leakage. For purposes of the present disclosure, the term gearbox 12 refers to the entire assembly including the main casing or housing 16, secondary housing or carrier 26 input and output shafts 18, 20, respectively, all internal components, such as gears 22 and bearings 24 within the casing 16. The terms gear casing, gear housing, casing and housing are used interchangeably, and refer to the enclosure in which the gears 22 and other power transfer components are contained.

[0016] Gears 22 and bearings 24 are contained in the housing 16 or secondary housing 26, portions of which are illustrated in FIGS. 2-3 and 8-9. An input shaft 20 is coupled to a motor (not shown) and a driven component such as a fan (not shown) is mounted or coupled to the output shaft 18.

[0017] The casing 16 has a secondary housing or horizontal carrier 26, isolator plate 28 and isolator 30 mounted to the casing 16. The carrier 26, isolator plate 28 and isolator 30 provide the penetration 14a through which the input shaft 20 exits the casing 16. The horizontal carrier 26 is mounted to the casing 16, the isolator plate 28 is mounted to the carrier 26 and the isolator 30 is mounted in an opening 32b in the isolator plate 28, as illustrated in FIGS. 2-4 and 8. The isolator 30 serves as a seal apparatus for the input shaft 20. The penetrations or bores 32a, 32b, 32c, respectively in the carrier 26, isolator plate 28 and isolator 30 are all concentric for passage of the shaft 20.

[0018] It will be appreciated that the gearbox 12 contains a media, such as oil, that serves as a lubricant for the gears 22 and bearings 24. The oil reduces friction and wear on the loaded rotating components such as the gears 22 and bearings 24, while also providing a cooling medium for the components. The lubricant, for example, oil, can however leak from the main housing 16 or secondary housing 26 at the casing penetrations 14a, 14b. For example, oil can leak from the interface of the input shaft 20 and the isolator 30 or at the isolator / rotor interface. Oil leakage can result in damage to the gearbox 16, or unwanted contamination of the surrounding area.

[0019] To contain the oil in the main housing 16 and secondary housing 26 and to reduce leakage, an embodiment of the present gear casing oil diverter system 10 uses a modified carrier 26 and isolator plate 28, as best seen in FIGS. 5-9. Referring first to FIGS. 7-9, the carrier 26 includes a body 34 that is generally circular in shape and has a forward or outboard end 36 and a rear or inboard end 38. The rear or inboard end 38 is mated with the main housing casing 16 and the isolator plate 28 is mounted to the forward or outboard end 36. An integral oil collection well 42 is formed within the lower radial projection 40. An oil return channel 44 extends from the oil collection well 42 longitudinally through the carrier 26 to provide fluid communication with the main housing 16 of the gearbox 12.

[0020] Referring to FIGS. 5, 6 and 8, the isolator plate 28 is generally circular in shape (to mate with the carrier forward end 36) and includes a radial projection 48 such that the isolator plate 28 mounts to and mates with the carrier forward end 36. The isolator plate projection 48 overlies the carrier projection 40 and oil collection well 42. The isolator plate 28 has a thickness t 28 that defines a concentric bore 32b. A section near the rearward end of the bore 32b has a reduced diameter, creating a lip 52 that serves as an isolation dam to limit the volume of oil allowed into the cavity 74 located immediately behind the isolator 30.

[0021] An integral oil passage 56 is formed in the isolator plate 28. In an embodiment, the oil passage 56 is formed as a channel that extends radially downward from the isolator plate bore 32b into the isolator plate projection 48. The oil passage 56 turns rearwardly, toward the rearward end 54 of the isolator plate 28, to an opening 60. The opening 60 aligns with the oil collection well 42 located in the carrier projection 40. In this manner, the isolator plate bore 32b is in fluid communication with the main reservoir of the main housing 16 via the oil passage 56 as it traverses through the isolator plate 28, into the carrier oil collection well 42 and through the carrier oil return channel 44. As best seen in FIG. 8, the oil return channel 44 is at a height h 44 above that at which the oil passage 56 empties into the oil collection well 42.

[0022] In an embodiment, the isolator plate 28 is secured to the carrier forward or outboard end 36 by a series of fasteners 62. The isolator stator is mounted in the isolator plate 28 by an interference fit.

[0023] Referring again to FIG. 8, oil is circulated in the gearbox 12 through one or more oil passages, such as passage 70. With respect to the carrier 26, oil flows into and around the bearings 24 and the shafts 18, 20. As such, oil will tend to leak at the penetration 14a of the shaft 20, and more specifically at the interface 72 of the isolator stator and rotor.

[0024] As oil flows toward the isolator 30, it is restricted from flowing beyond the isolator plate rearward end 54 by the isolation dam 52 of the plate 28. However, given the fluid nature of oil and the splashing action within the gearbox 12, oil may escape and flow over the isolation dam 52 and into the cavity 74 between the isolator 30 and isolator plate 28.

[0025] In the present system, oil that the finds its way into the cavity 74 will not leak from the isolator stator / rotor interface 72. Rather, the oil drains into the oil passage 56 and collects in the oil collection well 42. As the oil fills the oil collection well 42, it will reach the height or elevation of the oil return channel 44 in the carrier 26 and will drain toward the main housing 16, as indicated by the arrow at 76. In addition, the natural pumping action of the bearings 24 draws oil away from the oil return channel 44 and oil collection well 42 to greatly reduce or eliminate leakage at the shaft penetration and isolator stator / rotor interface 72.

[0026] It will be appreciated that the presently disclosed system to prevent or reduce oil leakage from a gearbox 12 by diverting the oil within the casing 16 from areas of the casing that include penetrations, for example penetration 72, is presented as an example only.

[0027] From the foregoing it will be observed that numerous modifications and variations can be made with respect to the specific embodiments illustrated herein within the scope of the appended claims which define the invention.

Claims

1. A gearbox (12) comprising: a main housing (16) carrying an input shaft (18) and an output shaft (20); a carrier (26) mounted to the main housing (16), the carrier (26) having a bore (32a), wherein one of the input shaft (18) and the output shaft (20) extends through the bore (32a) in the carrier (26); an isolator plate (28) mounted to the carrier (26) and having a bore (32b) aligned with the carrier bore (32a), wherein the one of the input shaft (18) and the output shaft (20) extends through the isolator plate bore (32b); an isolator (30) mounted to the isolator plate (28) and having a bore (32c) aligned with the isolator plate bore (32b), wherein the one of the input shaft (18) and the output shaft (20) extends through the isolator bore (32c), wherein the isolator plate (28) includes an interior surface and an oil passage (56) formed therein; characterized in that the carrier (26) includes an oil collection well (42), spaced from the carrier bore (32a), and an oil return channel (44) in fluid communication with the oil collection well (42) and extending through the carrier (26) to the main housing (16); and in that the passage (56) extends from the interior surface to the oil collection well (42), such that the interior surface is in fluid communication with the main housing (16) via the oil passage (56), the oil collection well (42) and the oil return channel (44); and in that the oil passage (56), the oil collection well (42) and the oil return channel (44) are configured to draw fluid at the interior surface into the main housing.

2. The gearbox of claim 1, wherein the oil passage (56), the oil collection well (42) and the oil return channel (44) define a flow path for the fluid from the interior surface into the main housing (16).

3. The gearbox of claim 1, wherein the oil passage (56) is a radially extending passage formed in the isolator plate (28).

4. The gearbox of claim 1, wherein the isolator plate (28) includes a projection (48) and wherein the oil passage (56) extends along the projection (48).

5. The gearbox of claim 4, wherein the projection (48) aligns with the oil collection well (42).

6. The gearbox of claim 1, wherein the isolator plate (28) includes a radially inward oriented lip (52), the lip (52) disposed adjacent the oil passage (56).

7. The gearbox of claim 1, wherein the oil return channel (44) is spaced from a bottom of the oil collection well (42).

8. The gearbox of claim 1, wherein the oil return channel (44) is oriented parallel to the carrier bore (32a).

9. The gearbox of claim 1, wherein the oil return channel (44) is oriented askew of the bore (32a) in the carrier (26).

10. The gearbox of claim 4, wherein the carrier (26) includes a projection (40) aligned with the isolator plate projection (48), and wherein the oil collection well (42) is formed in the carrier projection (40).

11. The gearbox of claim 1, wherein the oil return channel (44) extends from the isolator plate (28) to the main housing (16) and the oil return channel (44) is configured to return oil at the isolator (30) to the main housing (16).

12. The gearbox of claim 11, wherein the oil return channel (44) communicates with the bore (32b) in the isolator plate (28).

13. The gearbox of claim 11, wherein a portion of the oil return channel (44) is a radially extending passage formed in the isolator plate (28).

14. The gearbox of claim 11, wherein the isolator plate (28) includes a radially inward oriented lip (52), the lip (52) disposed adjacent the oil passage (56).