AU2001277421A1 - A cutter for debris removal from a propeller - Google Patents

Description

\ A Cutter for Debris Removal from a Propeller

Field of the Invention

The present invention relates to a cutter for cutting debris from a propeller. In particular, a marine vessel propeller.

Background of the Invention

Marine vessels, and in particular fishing vessels and crayfish boats often travel in water that contains rope and long-line fishing line. When the vessel passes over the rope or fishing line it will often become snagged around the spinning blades of the propeller, which, due to the spinning action, causes the rope, fishing line or other debris to become wound around the propeller shaft. As the debris is wound in, it builds up between the propeller and a bearing through which the propeller shaft rotates. Friction caused by the build up of rope can be created to the point where the debris, being made of plastics, can often melt and fill lubricating grooves of the bearing. This can prevent the flow of lubricating fluid through the bearing, which can cause the bearing to seize. Pressure due to the build up of debris pulls the propeller away from the bearing, which can damage the drive train that rotates the propeller shaft.

Some attempts have been made to arrange blades close to the propeller to attempt to cut away rope and other debris. Some of these blades are arranged to project laterally of the bearing thus attempting to cut rope as it is wound in. Other blades are arranged to point into a gap between a boss (rear) of the propeller and the bearing. In some instances, the bearing has been filled with a free wheeling collar member that attempts to fill this gap. The collar member is allowed to freely rotate about the propeller shaft so as to not block the lubricating grooves of the bearing. Sometimes the collar member includes holes that allow water to run therethrough.

Currently used blades have had limited success. However, they quite often result in a mass of tightly compacted debris that is beyond the reach of the blade and that can still cause damage.

Summary of the Present Invention

The present invention seeks to provide a new cutter that is more effective in cutting debris from the propeller. According to the present invention there is provided a cutter for cutting debris from a propeller including: a spool means fixed to a propeller shaft so as to rotate with the propeller shaft; a blade oriented to cut the debris from the spool means; whereby in use, debris snagged by the propeller is wound onto the spool means, whereupon it is cut away by the blade.

Preferably, the spool means is disposed between the propeller and a bearing holding the propeller shaft.

Preferably, the blade has a cutting edge oriented to cut debris build up moving towards the bearing. Preferably, the blade is arranged to be closely positioned to the spool means so that the blade glides over a circumferential surface of the spool means. Preferably, the spool means is substantially cylindrical.

Preferably, the blade is one of a plurality of blades.

Preferably, the cutting edge is oriented to cut into debris accumulating or moving generally longitudinally of the propeller shaft towards the bearing.

Preferably, the position of the blade is adjustable. Preferably, the blade is attached to a carrier of the bearing. Preferably, the blade overlaps the spool means. Preferably, the blade overlaps a liquid outlet of the spool means. Preferably, the spool means is a centrifugal pump.

Preferably, the cutting edge is one of a plurality of cutting edges, each cutting edge oriented to cut debris for one of the respective directions of rotation of the propeller. Preferably, the blade faces the propeller.

Detailed Description of Preferred Embodiments

In order to provide a better understanding of the present invention, a preferred embodiment will now be described in detail, by way of example only, with reference to the accompanying drawings:

Figure 1 is a cross-sectional side view of a propeller shaft housing carrying a preferred embodiment of a cutter in accordance with the present invention;

Figure 2 is an upper perspective view of a pair of cutters fixed to a propeller shaft carrier;

Figure 3 is a close-up view of the cutter in use cutting rope from the propeller;

Figure 4 is a bottom plan view of a mounting portion of the cutter of Figure 1 ;

Figure 5 is a side plan view of the mounting portion of Figure 4;

Figure 6 is a top view of the mounting portion of the cutter of Figure 4; Figure 7 is a plan view of a blade portion of the cutter of Figure 1 ;

Figure 8 is a side view of the blade portion of the cutter of Figure 7;

Figure 9 is a cross-sectional side view of the blade portion of Figure 8;

Figure 10 is a cross-sectional side view of the blade portion of Figure 7;

Figure 11 is a rear view of the blade portion of Figure 7; Figure 12 is a cross-sectional side view of an alternative blade portion; and

Figure 13 is a cross-sectional side view of an another blade portion.

Referring to Figure 1, there is shown a cutter 10 fixed to a carrier 12 for carrying a bearing 14. The carrier 12 is normally situated under the hull of a marine vessel by a mounting member 13. A propeller shaft 16 passes through the bearing 14 to rotate a propeller 18. The cutter 10 includes a laterally mounting portion 20 and a blade portion 22. The blade portion 22 faces the propeller 18. A spool 24 is located between the bearing 14 and a boss 28 of the propeller 18. The blade portion 22 overlaps with the spool 24 so that debris is removed from an end of the bearing 14 closest to the propeller 18. The spool 24 is fixed to the propeller shaft 16 so that it rotates with the propeller 18. The cutter 10 is fixed to the carrier 12 so that it remains stationary. In use, the propeller 18 and the spool 24 rotate about the propeller shaft 16 and will therefore be moving relative to the cutter 10.

Referring to Figure 2, a pair of cutters 10 and 10' are fixed to and laterally project from either side of the carrier 12. In front of the bearing 14 and carrier 12 is a separator 34 as described in International Patent Application No. PCT/AU00/00248. The spool 24 may be a centrifugal pump as described in International Patent Application Nos. PCT/AU01/00632.

In this case, channels 30 are provided in the pump to allow liquid through lubricating grooves in the bearing 14 to exit via the channels 30 at outlets 32 for each channel 30. The blade portions 22 and 22' overlap with the outlets 32 to clear debris from the outlets 32.

The carrier 12 includes a plurality of threaded holes 50 which are positioned so as to align with holes 40 in each mounting portion 20. A threaded bolt passes the holes 40 and screws into the threaded holes 50 so as to secure the mounting portion 20 to the carrier 12.

As best seen in Figure 7, oppositely facing blade edges 76 and 76' are located at the outer most lateral edge 42 of the mounting portion 20. The cutting edges 76 and 76' run longitudinally along the edge 42.

The mounting portion 20 includes a threaded hole 52 at a rear end 44 (closest to the propeller). The threaded hole 52 is for receiving another bolt that secures the blade portion 22 to the mounting portion 20. A hole 48 passes through the blade portion 22 for a bolt to pass through. The blade portion 22 includes a pair of cutting edges 46 and 46' that face the propeller 18. The blade portion also has another pair of cutting edges 45 and 45' that are parallel with the cutting edges 76 and 76'.

Referring to Figure 3, debris in this case rope 58, is shown snagged around the propeller 18, which has then been wrapped around the rear end of the propeller and then around the spool 24 due to the rotation of the propeller shaft 16. It can be seen that as the propeller shaft 16 continues to rotate the rope will build up in a direction moving away from the propeller 18, towards the bearing 14. As it moves closer to the bearing 14 it will eventually make contact with the cutting edges 46 or 46' of the blade portion 22. This results in the rope being shaved off, as indicated by strand 60. The more it builds up, the more it moves towards the blade and is cut away. Eventually the shaving of the rope will progress all the way through the width of the rope, or more likely, will cause the rope to be sufficiently weakened that it breaks.

If the marine vessel is travelling in reverse and the propeller shaft 16 will rotate in the opposite direction. The cutting edge 46' will be facing in a direction to cut debris from the spool 24 in the same manner as the cutting edge 46. Referring to Figures 4, 5 and 6, a surface 70 of the mounting portion 20 is shown. At each corner of the bottom surface 70 is a short leg 72. The legs 72 are provided so that a curve of the carrier 12 can be accommodated along the length of the bottom surface 70 and the mounting portion 20 secured firmly to the carrier 12. At the end 44 there is a slot 74. Leading inwardly from the slot 74 is the threaded hole 52.

Referring to Figure 7, the lateral edge 42 of the mounting portion 20 is shown with the upper cutting edge 76 and the lower cutting edge 76'. These cutting edges will remove where debris being wrapping around not only the propeller 18 but the entire carrier 12.

Referring to Figures 8, 9, 10 and 11, the blade portion 22 has a lower projection 80 that is received within the slot 74 of the mounting portion 20. This allows the blade portion 22 to slide within the slot 74 laterally with respect to the propeller shaft 16. The projection 80 includes a notch 82 at the base 83, which slides over the circumferential surface of the spool 24. An elongated hole 48 allows the bladed portion 22 to move while the bolt for securing the bladed portion 22 to the mounting portion 20 is in place, but not tightened. This movement allows the bladed portion 22 to be adjusted in its height from the spool 24. The bladed portion 22 is adjusted so that the base 83 almost touches or lightly touches the spool 24. The bolt is tightened to secure it in position. The bladed portion 22 then glides over the surface of the spool 24.

Referring back to Figure 2, the clearance between the base 83 of the bladed portion 22 and the spool 24, as indicated by 54, is very small to negligible. In the drawing, the two appear to be touching. In practice, they may be just touching and after a few revolutions of the spool 24 the bladed portion 22 will become properly seated so that the moving surface of the spool 24 glides underneath the relatively stationary undersurface of the bladed portion 22. The gap between the two is required to be very narrow so that debris does not enter the gap 54 between the two. Yet, the gap must be sufficiently wide so that the two surfaces may glide in relation to each other. It is undesirable for the bladed portion 22 to gouge into the spool 24.

Referring to Figures 10, 12 and 13, the cutting edge 46 is formed by an acute angle between an outer surface and a notch 86. Figure 10 shows an inner edge of the notch being perpendicular to the outer edge of the bladed portion 22. Figure 12 shows the inner edge of the notch being at an angle greater than 90° in relation to the outer surface of the bladed portion 22 and Figure 13 shows the notch being curved.

The method of use and operation of the present invention will now be described with reference to the accompanying drawings.

A cylindrical spool 24 is fixed to the propeller shaft so that it rotates with the propeller shaft. The diameter of the spool should be approximately the same as the outer diameter of the carrier 12.

The mounting portion 22 of each cutter 10 is mounted to a carrier 12 by positioning the feet 72 on either end of the curved outer surface of the carrier 12 and aligning holes 40 with the- threaded holes 50 in the carrier 12. Bolts are then screwed into position to securely attach each of the mounting portions 20 to the carrier 12. The projection 80 of the bladed portion 22 is inserted into the slot 74 and then positioned so that the base 83 of the bladed portion is almost or just touching the spool 24.

The position of the bladed portion 22 is then adjusted so that it nearly or just makes contact with the circumferential surface of the spool 24. A bolt is then inserted into the elongate hole 48 and threaded hole 52 and tightened to secure the bladed portion in position.

If any debris, such as rope, fishing line or other material becomes tangled with the propeller it will wrap around the spool 24 and continually tighten. As it becomes further entangled the debris will move towards the bearing where it will engage with the cutting edge 46 and be sliced away. The tighter the ravelling of the rope becomes, the more grip the spool has on the rope and the faster it is wound in and subsequently moves toward the blade. If the rope is then severed, any remaining rope within the reach of the bladed portion will continue to be sliced. Any other rope remaining there will be relatively harmless. If any further rope becomes entangled it will then cause either the first rope or the new rope to again move towards the bladed portion whereupon it will again be cut away. Any other rope that becomes tangled with the carrier will be caught by cutting edges 76 and 76' of the carrier portion 20 or cutting edge 45 of the bladed portion 12. If the vessel needs to reverse and the propeller shaft is rotated in the opposite direction, cutting edges 46', 76' and 45' performs the same function as cutting edges 46, 76 and 45, respectively.

The skilled addressee will appreciate that the present invention has the advantage of keeping tangled debris including rope and long fishing line away from the bearing and the lubricating fluid outlet of the bearing. The more rope that becomes tangled the faster it will move towards the cutting edge whereupon it will be cut away.

The preferred embodiment of the invention has an adjustable bladed portion that can be adapted to fix to a variety of sizes of a spool, the pool may be a centrifugal pump for pumping lubricating fluid through the bearing. The mounting portion is able to be mounted to a variety of shapes of carrier.

Modifications and variations can be made to the present invention without departing from the basic inventive concept. Such modifications include: (i) The number of cutters that may be mounted to a carrier;

(ii) The spool need not be a centrifugal pump as described in the preferred embodiment; and

(iii) The angle of the cutting edges need not be as shown in the preferred embodiment.

Such modifications and variations are deemed to be within in the scope of present invention, the nature of which is to be determined from the foregoing description.

Claims (14)

The claims defining the invention are as follows:

1. A cutter for cutting debris from a propeller including: a spool means fixed to a propeller shaft so as to rotate with the propeller shaft; a blade oriented to cut the debris from the spool means; whereby in use, debris snagged by the propeller is wound onto the spool means, whereupon it is cut away by the blade.

2. A cutter according to claim 1, wherein the spool means is disposed between the propeller and a bearing holding the propeller shaft.

3. A cutter according to claim 1, wherein the blade has a cutting edge oriented to cut debris build up moving towards the bearing.

4. A cutter according to claim 1, wherein the blade is arranged to be closely positioned to the spool means so that the blade glides over a circumferential surface of the spool means.

5. A cutter according to claim 1, wherein the spool means is substantially cylindrical.

6. A cutter according to claim 1, wherein the blade is one of a plurality of blades.

7. A cutter according to claim 3, wherein the cutting edge is oriented to cut into debris accumulating or moving generally longitudinally of the propeller shaft towards the bearing.

8. A cutter according to claim 1, wherein the position of the blade is adjustable.

9. A cutter according to claim 1, wherein the blade is attached to a carrier of the bearing.

10. A cutter according to claim 1, wherein the blade overlaps the spool means.

11. A cutter according to claim 1, wherein the blade overlaps a liquid outlet of the spool means.

12. A cutter according to claim 11, wherein the spool means is a centrifugal pump.

13. A cutter according to claim 3, wherein the cutting edge is one of a plurality of cutting edges, each cutting edge oriented to cut debris for one of the respective directions of rotation of the propeller.

14. A cutter according to claim 1, wherein the blade faces the propeller.