WO2005014389A1

WO2005014389A1 - Protecting shaft saels, eg for propellers

Info

Publication number: WO2005014389A1
Application number: PCT/AU2004/001062
Authority: WO
Inventors: Michael Shane Mcgrath
Original assignee: Michael Shane Mcgrath
Priority date: 2003-08-08
Filing date: 2004-08-09
Publication date: 2005-02-17

Abstract

Marine propeller shaft assembly (1), for counter-rotating propellers (not shown), includes inner shaft (2) and coaxial, counter-rotating, outer shaft (3). Seals are situated between shaft (3) and housing (5) and between inner and outer shafts (2, 3). To prevent fishing lines, weeds, etc from entangling on shafts (2, 3) and damaging the seals, protectors consisting of facing pair of cups (6, 7) and single cup (8) are positioned around the seals. In use, cups (6-8) rotate with their respective shafts (2 or 3) and cutting edges (71) on larger cup (7) and cup (8) sever and shred any fishing lines, etc caught by rotating shafts (2, 3).

Description

PROTECTING SHAFT SEALS, EG FOR PROPELLERS Field of the Invention. The present invention relates to the protection of seals on rotating shafts from damage foreign material and debris, such as fishing lines, and more particularly to the protection of seals on a propeller shaft, typically a propeller shaft of an outboard drive, preferably a counter-rotational assembly of an outboard drive. Background Art. The failure of seals associated with rotating shafts can present a number of problems and potentially result in the drive mechanism being severely damaged. Many outboard drives of marine water craft employ counter-rotational propeller systems that have a pair of counter-rotating shafts in series about a common rotational axis,. However, due to the counter-rotational effect these counter-rotational propeller systems are susceptible of being entangled with fishing lines or weeds which in tarn can cause damage to oil seals that ate typically disposed between the inner shaft and the outer shaft at the rear end of the outer shaft. One prior art apparatus shears the foreign matter by cooperative action of a rotating blade that rotates in conjunction with the propeller and a non-rotating blade supported on a non-rotating portion of the vessel. The non-rotating blade can move axially within its support. With each revolution, a slot follower connected to the non-rotating blade engages a slot carried by the rotating blade to adjust the axial position of the non-rotating blade to compensate for axial movement of the rotating blade. A wedge and valley mechanism prevents the two blades being forced apart during shearing action. U.S. Pat. Nos. 4,447,215; 4,507,091; 4,544,363 and 4,801,281 issued to the same applicant all disclose means for mounting both rotating and non-rotating shearing blades on the shaft so that axial shaft displacement has no effect on relative blade spacing. Other prior art devices mount the non-rotating member of a line shearing system to the strut or shaft bearing housing of the vessel. Although prior known seal covers disposed on the shafts about the oil seals generally prohibit fishing line, weeds or other similar material from wrapping about the inner shaft at the seal interface of the propeller shaft assembly, they wear and require replacement and complicate the process of assembling the propulsion system. Also, they do not remove the fishing line, weeds or other material. This has to be done manually, usually at the end of a boat trip. The devices are also usually multi part devices so that the number of parts are increased as is the chance of breakage and the expense of the devices. It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country. Summary of the Invention. The present invention is directed to a seal protecting device, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice. In a broad form, the invention resides in a seal protector device for protecting seals, typically oil seals, on rotating shafts, from foreign material, typically fishing lines, weeds and or any other similar material, wherein the seal protector device includes at least one protector member to be coupled relative to a shaft about the region of a seal, the at least one protector member having a cutting arrangement adapted to cut and shred said foreign material, wherein, in use, the at least one protector member is positioned relative to a seal such that as the shaft rotates, which causes the at least one protector member to rotate, any foreign material is severed by the rotating action of said cutting arrangement thereby protecting the seal by preventing foreign matter becoming entangled about the shaft in the region of the seal. Suitably, the at least one protector member may be provided with a

"cup-like" configuration. Suitably, a cup-like configuration may have a substantailly planar base wall and at least one sidewall extending therefrom. The base wall of the cup-like protector member may allow the protector member to be positioned relative to a housing or cowling and relative to a seal. The at least one side wall may suitably extend from an outer region of the basewall, and preferably at an angle to the base wall. Tyically, the angle will be between 0° and 90°. The angle at which the at least one side wall extends from the base wall may determine whether the protector member assumes a cup-like configration (angle closer to 90°) or a plate-like configuration (angle closer to 0°). The side wall may have a free edge. The base wall may be provided with an opening through which the shaft may extend. The opening may generally be a splined central aperture adapted to allow the protector member to be coupled on a propeller shaft having cooperating splines. Preferably, the cutting arrangement is at or adjacent to the free edge of the side wall and it may be or include a serrated edge, saw tooth edge, sharpened edge, combinations of these or any other suitable known cutting edge. The method of attachment of the at least one protector member relative to the phaft may be accompished in any manner, preferably by a substantially fluid-tight seal between the base wall of the at least one protector member and the housing or cowling. The direction of the side wall may be either towards or away from the housing or cowling. Facing the side wall towards the housing may reduce the chances of accidental injury of damage to objects contacting the at least one protector member when the propeller is exposed, for example when out of the water. In a second aspect, the invention resides in a seal protector device for protecting seals, typically oil seals, on rotating shafts, from foreign material, typically fishing lines, weeds and or any other similar material, wherein the seal protector device includes: a. at least two circular cups, one slightly larger than the other adapted to allow the smaller cup to fit within inside the larger cup and each cup is adapted to allow the cups cooperate in such a way so as to be coupled to a shaft about the region of a seal, b. at least one cup has a cutting edge adapted to cut and shred said foreign material, wherein, in use, each cup is positioned about a seal whereby the smaller cup fits within the larger cup so that both cups fully encompass the seal such that as the shaft rotates, which causes the cups to rotate, any foreign material is severed by the rotating action of said cutting edge thereby protecting the seal by preventing foreign matter becoming entangled about the shaft in the region of the seal. In a third aspect the invention resides in a propeller shaft assembly for a counter-rotating propeller system wherein the shaft assembly includes: a) an inner shaft which passes through and extends beyond a rear end of a coaxial outer shaft, b) at least one seal positioned between the inner and outer shaft proximate to the rear end of the outer shaft, c) seal protectors adapted to prevent foreign material, typically fishing lines or weeds or any other similar material, damaging the seal wherein the seal protector includes: i) a first circular cup adapted to be coupled to the inner shaft, ii) a second circular cup adapted to be coupled to the outer shaft and wherein the second circular cup is slightly larger in diameter than the first cup so to allow the first cup to fit within the second cup, d) at least one of circular cups having a cutting edge adapted to cut and shred said foreign matter, wherein, in use, the first circular cup is positioned along the inner shaft adjacent the seal and the second circular cup is positioned along the outer shaft adjacent the rear end of the outer shaft so that the first and second circular cups overlap to enclose the seal whereby as the two shafts counter-rotate any foreign material is severed by said cutting edge thereby protecting the seal by preventing foreign material from becoming entangled about inner and outer shafts in the region of the seal. Preferably, the cutting edge is a serrated edge, saw tooth edge, sharpened edge or any other suitable known cutting edge. Preferably, the cutting edge is on the second or larger circular cup, Preferably, the diameter of the first or smaller circular cup is substantially less than the diameter of the second or larger circular cup such that one circular cup is able to rotate relative to the other circular cup. Preferably, the difference between the diameter of the two circular cups is sufficient to create a minimal area for foreign material to enter and be severed or shredded by the cutting edge. Preferably, the second or larger circular cup has a splined central aperture adapted to allow the second or larger circular cup to be coupled on the outer shaft having cooperating splines. Preferably, the first or smaller circular cup has a central aperture adapted to allow the first or smaller circular cup to be coupled on the inner shaft. Preferably, the two cups are adapted to be positioned between two corresponding propeller blades. Preferably, a third circular cup with a cutting edge is adapted to be coupled to the outer shaft and positioned adjacent to and encompassing a seal positioned between the outer shaft and housing of the shaft assembly. Preferably, the seal protectors are adapted to be retrofitted to existing shaft assemblies. Brief Description of the Drawings. Various embodiments of the invention will be described with reference to the following drawings, in which: Figure 1 is a side view of a counter-rotation propeller shaft assembly with seal protectors in accordance with a first preferred embodiment of the invention. Figure 2 is a close up view of one of the seal protectors shown in figure 1. Figure 3 is a back end view of propeller shaft assembly with seal protectors as shown in figure 1. Figure 4 is a front end view of propeller shaft assembly with seal protectors as shown in figure 1. Figure 5 is a close up view of one of the seal protectors as shown in figure 1. Figure 6 is a side view of a splined circular cup with cutting edge in accordance to the preferred embodiment of the invention. Figure 7 is a bottom view of the seal protector shown in figure 6. Figure 8 is a top view of a non-splined circular cup in accordance to a preferred embodiment of the invention. Figure 9 is a close up view of a seal protectors according to a second preferred embodiment of the invention. Detailed Description of the Invention. According to a first aspect of the present invention, a seal protecting device for a counter-rotating dual propeller system is provided. The following description will describe the invention in relation to its use with marine propeller shaft assemblies, preferably counter-rotating propeller shafts, however it is envisaged that this invention ran be used in other fields where it is necessary to protect seals on a rotating shaft or counter-rotating shafts from foreign material, for example agricultural implements such as grass cutters or hay tedders. Turning, to figures 1 to 5, there is shown a marine propeller shaft assembly 1 having a counter-rotating shaft system. The shaft assembly I includes an inner shaft 2 and an coaxial outer shaft 3 through which the inner shaft 2 extends and passes through. The outer shaft 3 extends outward from a housing 5 a distance along the inner shaft 2 and the inner shaft 2 extends beyond a rear end of the outer shaft I A seal (not shown), typically an oil seal, is situated between the inner and outer shafts adjacent and within the rear end of the outer shaft 3. Another seal (not shown) is situated between the outer shaft 3 and the housing 5 adjacent and within the rear end of the housing 5. The outer shaft 3 has on its outer surface splines 4 for coupling with cooperating splines of a first propeller blade assembly. The inner shaft has similar splines for coupling second propeller blade assembly. To prevent foreign material such as fishing lines, weeds or any other similar material from being entangled on the shaft and damaging the seals, seal protectors are situated on the shafts to fully enclose the seals and are adapted to sever and shred foreign, material. The seal protectors consist of three circular cups, two 6, 7 for protecting the seal between the inner and outer shafts 2, 3 and the other 8 for protecting the seal between the outer shaft 3 and the housing 5. Turning to figures 6 to 8 in conjunction with figure 2, there is shown a seal protector for protecting the seal situated between the inner shaft 2 and outer shaft 3. The seal protector consists of two circular cups 6, 7 of differing sizes so that smaller cup 6 is able to fit within the other larger cup 7. The smaller cup has a central aperture 61 sized to allow the smaller cup 6 to slide over and couple to the inner shaft 2 (as shown in figures 2, 4). The larger circular cup 7 has a central aperture 73 sized to allow the cup 7 to slide over and be coupled to the outer shaft 3 (as shown in figures 2 and 3).

The larger cup 7 has splines 72 that couple with cooperating splines 4 on the outer shaft 3 so that the larger cup 7 rotates with and in the same direction as the outer shaft

3. Also the larger cup 7 has a cutting edge, shown as circular cutouts 7 1, however it is envisaged other known type of cutting edges can be used in place thereof

The cutting edge 71 is adapted to, in use, as the larger cup 7 rotates relative to the smaller cup 6 any foreign material that is caught by the rotating shafts, in the region of the seal protectors, is severed and shredded. Turning to figures 1, 3 and 5 the other seal protector includes a circular cup 8 similar to that of circular cup 7. Circular cup 8 has a splined central aperture 82 sized to allow the cup 8 to slide over and be coupled to the outer shaft 3. The diameter of the circular cup 8 is dimensioned to just fit over and extend over part of the housing 5 so that the seal between the outer shaft 3 and the housing 5 is enclosed by the circular cup 8 and the circular cup 8 is able to rotate relative to the housing 5. The circular cup 8 has cutting edges 81 (similar to the cutting edges 71 of circular cup 7) so that any foreign material that is caught by the rotating shaft in the region of the circular cup 8 is severed and shredded. It is envisaged that the seal protectors can be fitted at the time of manufacture of the shaft assembly, however it is more preferable that they be sold as separate units and retrofitted to existing shaft assemblies. In use with the seal protectors in place as shown in figure 1 and with the propeller blade assemblies attached, the seals (which previously were exposed to foreign material), are fully enclosed by the seal protectors 6, 7 and 8. Therefore, any foreign material caught by the propeller blades that is wound onto the shafts is severed and shredded when it comes into contact with the seal protectors, thus preventing damage to the seals. According to a second aspect of the invention, the seal protection device may be provided to suit a single propeller system as opposed to the dual propeller system illustrated and discussed above with reference to the first preferred embodiment. This aspect of the invention is illustrated in Figure 9. The propeller shaft 11 has on its outer surface splines 4 for coupling with cooperating splines of the propeller blade assembly and no inner shaft for coupling second propeller blade assembly is provided. The protector member is provided as a circular cup 8 having a splined central aperture 82 sized to allow the cup 8 to slide over and be coupled to the propeller shaft 11. The diameter of the circular cup 8 is dimensioned to just fit over and extend over part of the housing 5 so that the seal between the propeller shaft 11 and the housing 5 is enclosed by the circular cup 8 and the circular cup 8 is able to rotate relative to the housing 5. The circular cup 8 has cutting edges 81 (similar to the cutting edges 71 of circular cup 7 in the first embodiment) so that any foreign material that is caught by the rotating shaft in the region of the circular cup 8 is severed and shredded. The circular cup 8 illustrated has a substantailly planar base wall 12 and a cylindrical sidewall 13 extending therefrom. The base wall 12 of the circular cup 8 allows the circular cup 8 to be positioned relative to a housing or cowling 5 and relative to a seal. The side wall 13 extends from an outer region of the basewall 12, and at an angle to the base wall 12. The angle at which the side wall 13 extends from the base wall 12 in the protector member illustrated in Figure 9 is closer to 90° and therefore, the protector member assumes a cup-like configration. As stated above,a plate-like configuration (angle closer to 0°) is also possible. The side wall has a free cutting edge. The orientation of the protector member may be such that the direction of the side wall 13 can be either towards or away from the housing or cowling 5. Facing the side wall towards the housing 5 as illustrated in Figure 9 may reduce the chances of accidental injury of damage to objects contacting the cutting arrangement when the propeller is exposed, for example when out of the water. ADVANTAGES ■ removes foreign material away from the regions of the seals ■ able to be retrofitted to existing shaft assemblies ■ improves life expectancy of the seals ■ able to be replaced easily ■ no need to replace seals after foreign material is entangled on shafts. In the present specification and claims, the word "comprising" and its derivatives including "comprises" and "comprise" include each of the stated integers but does not exclude the inclusion of one or more further integers. Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics maybe combined in any suitable manner in one or more combinations. In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Claims

1. A seal protector device for protecting seals, typically oil seals, on rotating shafts, from foreign material, typically fishing lines, weeds and or any other similar material, wherein the seal protector device includes at least one protector member to be coupled relative to a shaft about the region of a seal, the at least one protector member having a cutting arrangement adapted to cut and shred said foreign material, wherein, in use, the at least one protector member is positioned relative to a seal such that as the shaft rotates, which causes the at least one protector member to rotate, any foreign material is severed by the rotating action of said cutting arrangement thereby protecting the seal by preventing foreign matter becoming entangled about the shaft in the region of the seal.

2. A seal protector device as claimed in claim 1 wherein at least one protector member has a substantailly planar base wall and at least one sidewall extending therefrom, the at least one side wall extending from an outer region of the base wall, at an angle to the base wall of between 0° and 90°.

3. A seal protector device for protecting seals, typically oil seals, on rotating shafts, from foreign material, typically fishing lines, weeds and or any other similar material, wherein the seal protector device includes: i. at least two circular cups, one slightly larger than the other adapted to allow the smaller cup to fit within inside the larger cup and each cup is adapted to allow the cups cooperate in such a way so as to be coupled to a shaft about the region of a seal, ii. at least one cup has a cutting edge adapted to cut and shred said foreign material, wherein, in use, each cup is positioned about a seal whereby the smaller cup fits within the larger cup so that both cups fully encompass the seal such that as the shaft rotates, which causes the cups to rotate, any foreign material is severed by the rotating action of said cutting edge thereby protecting the seal by preventing foreign matter becoming entangled about the shaft in the region of the seal.

4. A seal protector device as claimed in claim 1 wherein the cutting edge is a serrated edge, saw tooth edge, shaφened edge or any other suitable lαiown cutting edge.

5. A seal protector device as claimed in claim 3 wherein the cutting edge is on the second or larger circular cup.

6. A seal protector device as claimed in claim 3 wherein the diameter of the first or smaller circular cup is substantially less than the diameter of the second or larger circular cup such that one circular cup is able to rotate relative to the other circular cup.

7. A seal protector device as claimed in claim 1 wherein the at least one protector member has a splined central aperture adapted to allow the at least one protector member to be coupled relative to a shaft having cooperating splines.

8. A seal protector device as claimed in claim 3 wherein a third circular cup with a cutting edge is adapted to be coupled to the outer shaft and positioned adjacent to and encompassing a seal positioned between the outer shaft and housing of the shaft assembly.

9. A seal protector device as claimed in claim 1 wherein the seal protector is adapted to be retrofitted to an existing shaft assembly.

10. A propeller shaft assembly for a counter-rotating propeller system wherein the shaft assembly includes: a. an inner shaft which passes through and extends beyond a rear end of a coaxial outer shaft, b. at least one seal positioned between the inner and outer shaft proximate to the rear end of the outer shaft, c. at least one seal protector device including at least one protector member to be coupled relative to a shaft about the region of a seal, the at least one protector member having a cutting arrangement adapted to cut and shred said foreign material, wherein, in use, the at least one protector member is positioned relative to a seal such that as the shaft rotates, which causes the at least one protector member to rotate, any foreign material is severed by the rotating action of said cutting arrangement thereby protecting the seal by preventing foreign matter becoming entangled about the shaft in the region of the seal.