Propeller including a discrete blade edge cover member

Abstract

THIS invention relates to a propeller and more particularly but not exclusively, to a propeller for use with inboard and outboard boat engines. The propeller includes a hub and a plurality of blades extending radially outwardly from the hub, wherein each blade comprises a blade body having a blade face and a blade back, with the blade body terminating in a peripheral zone. The propeller also includes blade edge covering members which are releasably securable to at least part of the peripheral zone of the blade so as to cover a radially outer edge of the peripheral zone.

Claims

1. A propeller including: a hub; a plurality of blades extending radially outwardly from the hub, wherein each blade comprises a blade body having a blade face and a blade back, with the blade body terminating in a peripheral zone; and a blade edge covering member formed from a plastic material which is removably securable to at least part of the peripheral zone of the blade so as to cover an outer edge of the peripheral zone; wherein the blade edge covering member includes two opposing lip sections that straddle the blade body in use, with one lip section overlying a peripheral zone of the blade face, and the other lip section overlying a peripheral zone of the blade back; and wherein the blade face and the blade back include recessed zones for receiving the lip sections of the blade edge covering member, in order for the lip sections to be flush with the blade face and/or blade back when secured to the blade; wherein a plurality of apertures are provided through the peripheral zone of the blade; and wherein the lip sections include integral engagement formations in the form of cylindrical protrusions provided on and extending from the lip sections toward one another, with the engagement formations from one of the lip sections adapted to engage the engagement formations provided on the other of the lip sections through the apertures in the blade.

2. The propeller of claim 1, wherein the peripheral zone comprises a leading edge, a trailing edge and a blade tip zone extending between the leading edge and the trailing edge.

3. The propeller of claim 2, wherein a single blade edge covering member covers the leading edge, blade tip zone, and the trailing edge of the blade.

4. The propeller of claim 1, wherein the blade edge covering member is substantially U-shaped in cross-section.

5. The propeller of claim 1, wherein the blade edge covering member comprises two halves, with each half including one of the lip sections.

6. The propeller of claim 1, wherein the blade edge cover member is made from a hygroscopic, resilient plastic material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Two embodiments of the invention are described by way of non-limiting examples, and with reference to the accompanying drawings in which:

(2) FIG. 1 is a front perspective view of the propeller including two blade edge cover members in accordance with one embodiment of the invention;

(3) FIG. 2 is rear perspective view of the propeller of FIG. 2;

(4) FIG. 3 is an exploded perspective view of the propeller of FIG. 1;

(5) FIG. 4 is a front perspective view of a propeller body suitable for receiving a single blade edge cover member in accordance with another embodiment of the invention;

(6) FIG. 5 is a perspective view of the blade edge cover member used in FIG. 4;

(7) FIG. 6 is a plan view of the blade edge cover member of FIG. 5; and

(8) FIG. 7 is a side view of a propeller comprising a propeller body of FIG. 4 fitted with the blade edge cover member of FIG. 5.

DETAILED DESCRIPTION OF INVENTION

(9) Referring to the drawings, in which like numerals indicate like features, a non-limiting example of propeller in accordance with the invention is generally indicated by reference numeral 10.

(10) The propeller 10 comprises a hub 20, which may be of many different configurations. In one embodiment the hub 20 incorporates a secondary propulsion system as described in the applicants co-pending application ZA2012/05757 entitled Propeller incorporating a secondary propulsion system, the contents of which is incorporated herein by reference. In one embodiment the propeller also includes a flow guide provided on a back face of a blade of the propeller as described in the applicant's co-pending application ZA2012/05758 entitled Propeller incorporating a blade back flow guide, the content of which is also incorporated herein by reference.

(11) A plurality of blades 30 extend radially outwardly from the hub 20, with each blade being in the form of an airfoil extending from the hub 20 at a root 23 section thereof, and terminating in a peripheral tip zone 34. The blade 30 includes a blade face 31 and a blade back 32. The periphery of the blade 30 comprises a leading edge 35, a trailing edge 36, and an outer tip zone 34 extending between the leading edge 35 and the trailing edge 36.

(12) A plurality of apertures 37 are provided through the blade adjacent the periphery of the blade, and more particularly in an area where an blade edge cover member 40 is to be releasably secured. The combination of apertures 37 to which a sleeve formation 40 is to be secured defines a receiving means of the blade. An edge zone 39 of the blade face may be at least partially recessed in order to receive a lip formation 42 of the blade edge cover member 40 in a substantially flush configuration.

(13) Removable blade edge cover members 40 in the form of plastic moulded bodies are provided. In the embodiment shown in FIGS. 1 to 3 the propeller 10 includes two such edge formations, being a trailing edge blade edge cover member 40.1 and a tip zone blade edge cover member 40.2. In the embodiment shown in FIGS. 4 to 7, a single blade edge cover member 40.3 is provided, and in use covers substantially the entire periphery of the blade.

(14) Each blade edge cover member 40 comprises an arcuate body 41 that follows the profile of the periphery of the blade. The body 41 is made from a flexible hygroscopic material, and an outer edge, or tip section 41.1 of the body is at least partially rounded. A lip formation 42 extends radially inwardly from the body, and is configured and dimensioned to fit inside a recess 39 in an edge zone of the blade, and more particularly in a recess provided in the blade face 31 or the blade back 32 of the blade 30. This means that the edge member will be flush with the remainder of the blade when installed.

(15) Cylindrical protrusions 43 extend upwardly from the lip formation 42, and are configured and dimensioned to fit inside the apertures 37 provided in the edge zone of the blade 30. This enables the blade edge cover member 40 to be removably secured to the blade.

(16) In the embodiment shown in FIGS. 1 to 3, the edge cover member 40 only includes one lip section 41, and more particularly only overlies part of the blade face 31. In this embodiment upper surfaces 43.1 of the protrusions are at least partially rounded, and may protrude slightly above the surface of the blade back 32.

(17) In the embodiment shown in FIGS. 4 to 7 the edge cover member 40 includes two opposing lip sections 42, in order for the edge cover member 40 to be adapted, in use, to straddle the peripheral zone of the blade body. In this case recesses 39 will be provided in both the blade face 31 and the blade back 32. In addition, complementary engagement formations 43 will extend from both lip sections towards one another, with opposing engagement formations of the opposing lip sections adapted to engage on another through the apertures 37.

(18) It will appreciated that the propeller may include only a trialing edge blade edge cover member 40.1, alternatively only a tip zone blade edge cover member 40.2, or a single edge cover member 40.3 that covers both the trailing edge and the blade tip. In addition, the same or a further edge cover member may also cover the leading edge of the blade.

(19) The trialing edge blade edge cover member 40.1 may take various configurations, and the cross-sectional profile may be selected in order to selectively adjust the pitch and cupping of the blade. The use of the trialing edge blade edge cover member 40.1 therefore enables the performance of the propeller to be adjustable, and allows the use of one propeller body for a range of different requirement specifications.

(20) The use of the tip zone blade edge cover member 40.2 is first and foremost a safety feature, and the resilient nature and the choice of a hygroscopic material prevents a finger or limb from being drawn into the propeller blades. Also, the tip zone blade edge cover member 40.2 is made from a material that is not prone to wear should the blade hit rocks or other hard materials. Should the blade edge cover member wear, the blade edge cover member can still be replaced without the need to replace the body of the propeller. In addition to the above, tip zone blade edge cover members 40.2 of various widths may be used to alter the effective diameter of the propeller, which again improves the versatility of the propeller.

(21) In the case of the singular edge cover member 40.3, the same design considerations as used for the discrete edge cover members (40.1 and 40.2) can be applied.

(22) The blade edge cover member 40.3 shown in FIGS. 4 to 7 consists of two halves, but may conceivably also be in the form of one integrally formed article.

(23) The propeller 10 body is made from magnesium or a magnesium alloy, which is made in a moulding process known in the art.

(24) It will be appreciated that the above is only one embodiment of the invention and that there may be many variations without departing from the spirit and/or the scope of the invention.