Abstract
An end cap for guiding an exhaust gas flow of a boat engine. The end cap is configured to be attached onto a propeller nut of the boat engine. The end cap including: a base body having a bottom surface, a lateral surface and a tip, the tip and the bottom surface being spaced apart from each other in a longitudinal direction of the base body. The lateral surface extends from the bottom surface and converges in the tip. The bottom surface having a recess for receiving the propeller nut; and at least one exhaust gas-guiding structure extends helically along the lateral surface.
Claims
1. An end cap for guiding an exhaust gas flow of a boat engine, wherein the end cap is configured to be attached onto a propeller nut of the boat engine, the end cap comprising: a base body having a bottom surface, a lateral surface and a tip, the tip and the bottom surface being spaced apart from each other in a longitudinal direction of the base body; wherein the lateral surface extends from the bottom surface and converges in the tip; the bottom surface having a recess for receiving the propeller nut; and at least one exhaust gas-guiding structure extends helically along the lateral surface.
2. The end cap according to claim 1, wherein an amount that the gas-guiding structure extends radially from the bottom surface decreases toward the tip of the base body is along a longitudinal direction of the base body.
3. The end cap according to claim 2, wherein the gas-guiding structure has one of a convex, conical or concave form.
4. The end cap according to claim 1, wherein the exhaust gas-guiding structure ends at the tip or before reaching the tip.
5. The end cap according to claim 1, wherein the exhaust gas-guiding structure includes one of: at least two exhaust gas guiding elements symmetrically offset to each other and helically running around the lateral surface; or at least six exhaust gas guiding elements.
6. The end cap according to claim 1, wherein the exhaust gas-guiding structure includes at least one projection protruding from the lateral surface in a radial direction.
7. The end cap according to claim 6, wherein a height of the at least one projection in the radial direction at a position nearest the tipis one of 10% to 20%, 20% to 70%, or 40% to 50%, of a diameter of the bottom surface.
8. The end cap according to claim 1, wherein the exhaust gas-guiding structure includes at least one groove embedded in the lateral surface.
9. The end cap according to claim 1, wherein the base body is cylindrical starting at the bottom surface and decreases in width towards the tip.
10. The end cap according to claim 1, wherein a width of the base body decreases in the longitudinal direction from the bottom surface toward the tip.
11. The end cap according to claim 10, wherein a curvature of the lateral surface increases in the longitudinal direction from the bottom surface toward the tip.
12. The end cap according to claim 1, wherein one or more of the tip or the lateral surface are completely closed in the area of the tip.
13. The end cap according to claim 1, wherein the lateral surface having at least one bore for receiving a cotter pin, the bore extending transversely to the longitudinal direction of the base body.
14. The end cap according to claim 1, wherein the bore extending entirely through a width of the lateral surface.
15. The end cap according to claim 1, wherein the recess is configured as a blind hole comprising an outer first receiving section, and an inner second receiving section, the second receiving section is configured deeper from the bottom surface than the first receiving section.
16. The end cap according to claim 15, wherein one or more of the first receiving section has a circular outer circumference or the second receiving section has a hexagonal outer circumference.
17. The end cap according to claim 1, wherein the blind hole further comprises a third receiving section disposed centrally in the second receiving section and is deeper from the bottom surface than the second receiving section, the third receiving section having a circular outer circumference.
18. A propeller system for a boat engine, the propeller system comprising: a propeller; a propeller shaft; a propeller nut, wherein the propeller is fixed on the propeller shaft by the propeller nut, wherein the propeller has an exhaust gas duct which is disposed concentrically around the propeller shaft; and the end cap according to claim 1, the end cap being attached onto the propeller nut, so that the end cap is one of disposed centrally in the exhaust gas duct or disposed at an end of the exhaust gas duct.
19. A boat engine comprising: the propeller system according to claim 18.
20. The boat engine according to claim 19, wherein the boat engine is configured as an outboard engine.
21. A method for guiding an exhaust gas flow of a boat engine, the method comprising: fixing an end cap to a propeller nut of the boat engine; and directing exhaust from the boat engine along a gas-guiding structure extending helically along a lateral surface of the end cap.
22. The method according to claim 21, wherein the fixing comprises fixing the end cap with a cotter pin.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Further embodiments will become apparent from the description of the embodiments together with the claims and the attached drawings. Embodiments may fulfill individual features or a combination of several features.
[0036] The embodiments will be described below without restricting the general inventive idea on the basis of exemplary embodiments with reference to the drawings, and regarding any details which are not explained further in the text reference is expressly made to the drawings. In the drawings:
[0037] FIG. 1 illustrates a schematically simplified illustration of a boat engine in the form of an outboard engine,
[0038] FIG. 2 illustrates a schematically simplified exploded illustration of a propeller system with a propeller, a propeller nut and a cotter pin,
[0039] FIG. 3 illustrates a schematically simplified perspective illustration of a propeller nut,
[0040] FIG. 4 illustrates a schematically simplified perspective illustration of a propeller system with a propeller nut screwed onto the propeller shaft,
[0041] FIG. 5 illustrates a schematically simplified illustration of a propeller system with an end cap attached onto the propeller nut,
[0042] FIG. 6 illustrates a schematically simplified side view of an end cap in a first embodiment,
[0043] FIG. 7 illustrates a schematically simplified plan view of an end cap according to the first embodiment,
[0044] FIG. 8 illustrates a schematically simplified view from below of an end cap according to the first embodiment,
[0045] FIG. 9 illustrates a schematically simplified perspective illustration of an end cap in a first embodiment,
[0046] FIG. 10 illustrates a schematically simplified perspective illustration of a propeller system with an end cap according to a second embodiment,
[0047] FIG. 11 illustrates a schematically simplified perspective illustration of an end cap according to the second embodiment,
[0048] FIG. 12 illustrates a schematically simplified perspective illustration of a propeller system with an end cap according to a third embodiment,
[0049] FIG. 13 illustrates a schematically simplified side view of the end cap according to the third embodiment,
[0050] FIG. 14 illustrates a schematically simplified side view of an end cap in a fourth embodiment,
[0051] FIG. 15 illustrates a schematically simplified perspective view of the fourth embodiment,
[0052] FIG. 16 illustrates a schematically simplified plan view of the tip of the fourth embodiment, and
[0053] FIG. 17 illustrates a schematically simplified plan view of the bottom side of the fourth embodiment.
[0054] In the drawings, the same or similar types of elements and/or parts are provided with the same reference numbers so that a corresponding re-introduction is omitted, respectively.
DETAILED DESCRIPTION
[0055] FIG. 1 shows schematically simplified in a side view a boat engine 1, which is configured as an outboard engine in the example shown. Such boat engines 1 configured as outboard engines are frequently used for driving motor boats and as auxiliary propulsion for sailboats. For this purpose, the outboard engine is fixed to the stern of the boat. In operation of the boat engine 1, an upper part of the boat engine 1 emerges from the water, while a lower part is in the water. The lower part of the boat engine 1 comprises a propeller system 2 with a propeller 3, which imparts the outboard engine the necessary propulsion. For the ejection of exhaust gases, in addition, the propeller system 2 includes an exhaust gas duct 6, which extends between the blades of the propeller 3 to the rear and, at least when driving forward, generates a rearward exhaust gas flow.
[0056] FIGS. 2, 3 and 4 show an assembly of the propeller system 2 in a schematically simplified manner As shown in FIG. 2, a propeller nut 5 is provided for fixing the propeller 3, which is fixed on propeller shaft not shown in FIG. 2 by a cotter pin 7, in order to fasten the propeller 3 on the propeller shaft. FIG. 3 shows an enlarged view of this propeller nut 5, where it is visible that the propeller nut 5 has a hexagonal cross-section and includes recesses at its top between the edges, respectively. In FIG. 4, the propeller system 2 is illustrated in a mounted state, where the propeller 3 is fixed on the propeller shaft 4 by the propeller nut 5. The propeller shaft 4 and the propeller nut 5 are thus centrally located at an exit of the exhaust gas duct 6 of the propeller 3.
[0057] The exhaust gas flow exiting from the exhaust gas duct 6 can stall during travel, inter alia, due to the nature of the propeller nut 5 and turbulences occur, which negatively affect the flow efficiency in the water. In order to solve this problem, the end cap 10 is provided, which is attached onto the propeller nut 5, as illustrated in a schematically simplified manner in FIG. 5. For fixing the end cap 10, for example, the cotter pin 7 is used, which is not shown in FIG. 4 and FIG. 5 for reasons of clarity. In the embodiment illustrated in FIG. 5, the end cap 10 comprises an exhaust gas guiding structure 20 with multiple exhaust gas guiding elements formed as projections or helixes, with which a suction in the exhaust gas flow is generated additionally, which exerts a positive influence on the exhaust gas counter pressure of the boat engine 1. Thereby, the heterogeneous turbulences are converted into a directed vortex with a suction effect, whereby the efficiency of the boat engine 1 is improved, so that the speed of the boat can be increased and/or the fuel consumption of the boat engine 1 can be reduced.
[0058] FIGS. 6 to 9 show a first embodiment of the end cap 10 in different views. In the schematically simplified side view shown in FIG. 6, the end cap 10 includes a base body 12 having a bottom surface 16 and a lateral surface 14 extending from the bottom surface 16 up to a tip 19. Six exhaust gas-guiding elements 21 configured as projections or helixes 22 wind spirally around the lateral surface 14 from the bottom surface 16 in the direction of the tip 19. For reasons of clarity, in FIG. 6 and the following figures, however, only one of the helixes 22 is indicated as an exhaust gas-guiding element 21, although all helixes 22 are also exhaust gas guiding elements 21. The height of the helixes 22, thus their radial extension away from the lateral surface 14, decreases in the direction of the tip 19. All of the exhaust gas guiding elements 21 of the exhaust gas guiding structure 20 end below the tip 19. A bore 36 is provided on the propeller nut 5 for fastening the end cap 10.
[0059] In the plan view of FIG. 7, it is illustrated in a schematically simplified manner that the exhaust gas guiding elements 21 configured as helixes 22 are configured symmetrically offset to each other on the lateral surface 14.
[0060] FIG. 8 shows the end cap 10 viewed in a schematically simplified manner from below. In this view, it is visible that the bottom surface 16 is designed annularly and comprises a recess 18 in its center. The recess 18 is configured as a stepped blind hole 30, which comprises an exterior first receiving section 31, a central second receiving section 32 and an inner third receiving section 33. The internal third receiving section 33 is the deepest section and has a circular outer circumference, so that it can receive the protruding part of the propeller shaft 4, as illustrated in FIG. 4. The central second receiving section 32 is shallower than the third receiving section 33 but deeper than the first receiving section 31. The second receiving section 32 is configured for receiving the propeller nut 5 and for this reason has a hexagonal outer circumference. The exterior first receiving section 31 is the shallowest receiving section and is configured and intended to receive the section of the propeller shaft 4, which is disposed below the propeller nut 5, as illustrated in FIG. 4. The number and exact configuration of the different receiving sections 31, 32, 33 is in FIG. 8 purely exemplary and may be adapted to different propeller systems 2 of boat engines 1 in order to securely fasten the end cap 10 on propeller shafts 4 respectively propeller nuts 5 of different engine types. FIG. 9 shows the first embodiment of the end cap 10 in a schematically simplified perspective illustration. In this illustration, the different directions of the end cap 10 are indicated in the form of the longitudinal direction 40, the radial direction 50 and the circumferential direction 60. In addition, bore 36 can be seen clearly. Bore 36 extends through the entire width of the base body 12 and thereby passes through the second receiving section 32. By the bore 36, the end cap 10 gets simply and securely fastened on the propeller nut 5 by using the cotter pin 7, which is already provided for fixing the propeller nut 5, and now also used for fixing the end cap 10.
[0061] FIG. 10 shows in a schematically simplified manner a propeller system 2a with an end cap 10a according to a second embodiment. In this embodiment, the exhaust gas guiding structure 20a having gas guiding elements 21a are not configured as helixes 22, but as grooves 24, as illustrated in the schematically simplified perspective illustration of the end cap 10a in FIG. 11. Just like the helixes 22 of the first embodiment, the grooves 24 of the second embodiment wind helically around the lateral surface 14a of the base body 12a from the bottom surface 16a towards the tip 19a. Also as in the first embodiment, the exhaust duct structure 20a in the second embodiment includes a total of six exhaust gas-guiding elements 21.
[0062] A third embodiment of the end cap 10b is illustrated in the FIGS. 12 and 13. As in the schematically simplified perspective illustration of the propeller system 2b in FIG. 12 visible, the exhaust gas guiding structure 20b according to the third embodiment, in turn, includes exhaust gas guiding elements 21b configured as projections or helixes 22b radially extending from the lateral surface 14b of base body 12b from the bottom surface 16b towards the tip 19b. As shown in the schematically simplified side view in FIG. 13, however, the helixes 22b are significantly larger than according to the first embodiment. In other words, the height of the helixes 22b, thus the extension in the radial direction 50, is significantly more pronounced than in the first embodiment. However, in the third embodiment, only three instead of six exhaust gas-guiding elements 21b are provided.
[0063] Which type of end cap is used for a given boat engine 1 depends, inter alia, on the propeller size of the propeller 3, the speed and the type of the boat engine 1. In any case, by using the end cap, the occurrence of turbulences in the exhaust gas flow is reduced or avoided and the efficiency of the boat engine 1 is improved.
[0064] FIGS. 14 to 17 show different views of a fourth embodiment of an end cap 10c. This one differs from the preceding embodiments basically in the concave configuration of the lateral surface 14c of the base body 12c, which ends in a flattened tip 19c. In this case, the helix 22c of the exhaust gas guiding elements 21c of the gas guiding structure 20c runs up to the tip 19c of the base body 12c. The concave structure is modelled on the characteristic of an exhaust gas vortex behind the propeller. The end cap 10c having a bottom surface 16c with a bottom shown in FIG. 17, which is configured similarly to that in FIG. 8, 9 or 11. While there has been shown and described what is considered to be embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact forms described and illustrated, but should be constructed to cover all modifications that may fall within the scope of the appended claims.
LIST OF REFERENCE SIGNS
[0065] 1 Boat engine [0066] 2, 2a, 2b Propeller system [0067] 3 Propeller [0068] 4 Propeller shaft [0069] 5 Propeller nut [0070] 6 Exhaust gas duct [0071] 7 Cotter pin [0072] 10, 10a, 10b, 10c End cap [0073] 12, 12a, 12b, 12c Base body [0074] 14, 14a, 14b, 14c Lateral surface [0075] 16, 16a, 16b, 16c Bottom surface [0076] 18 Recess [0077] 19, 19a, 19b, 19c Tip [0078] 20, 20a, 20b, 20c Exhaust gas-guiding structure [0079] 21, 21a, 21b, 21c Exhaust gas-guiding element [0080] 22, 22b, 22c Helix [0081] 24 Groove [0082] 30 Blind hole [0083] 31 First receiving section [0084] 32 Second receiving section [0085] 33 Third receiving section [0086] 36 Bore [0087] 40 Longitudinal direction [0088] 50 Radial direction [0089] 60 Circumferential direction
