AU2003100876A4 - Seal Protecting Device - Google Patents

Description

SEAL PROTECTING DEVICE FIELD OF 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 OF INVENTION 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 turn can cause damage to oil seals that are typically disposed between the inner shaft and the outer shaft at the rear end of the outer shaft.

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 and also 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.

OBJECT OF INVENTION It is therefore an object of the invention to provide a seal protection device for the protection of seals on rotating shafts that ameliorates some of the disadvantages and limitations of known art or at least provide the public with a useful choice.

G:\s399AUIspec. 1003.doc SUMMARY OF INVENTION In one 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 including: 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 second 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- G:\s399AUIspec.1003.doc 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.

Any other aspect hereinafter described.

G:\s399AUIspec.1003.doc BRIEF DESCRIPTION OF DRAWINGS A preferred embodiment of the invention will now be described by way of example only, to the accompanying drawings.

Figure 1 is a side view of a counter-rotation propeller shaft assembly with seal protectors in accordance to preferred embodiments 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.

DESCRIPTION OF INVENTION 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 can 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.

G:\s399AUIspec.1003.doc Turning to figures 1 to 5, there is shown a marine propeller shaft assembly 1 having a counterrotating shaft system. The shaft assembly 1 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 3.

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 4 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 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 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 71, 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, G:\s399AUIspec. I 003.doc 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.

ADVANTAGES

L removes foreign material away from the regions of the seals a able to be retrofitted to existing shaft assemblies L improves life expectancy of the seals U able to be replaced easily L no need to replace seals after foreign material is entangled on shafts.

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VARIATIONS

It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is herein set forth.

Throughout the description of this specification the word "comprise" and variations of that word such as "comprises" and "comprising", are not intended to exclude other additives, components, integers or steps.

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