US3908578A

US3908578A - Exhaust systems for aquatic craft

Info

Publication number: US3908578A
Application number: US367616A
Authority: US
Inventors: Eggert Buelk
Original assignee: Rockwell International Corp
Current assignee: ARKOS SpA; Boeing North American Inc
Priority date: 1973-06-06
Filing date: 1973-06-06
Publication date: 1975-09-30
Anticipated expiration: 1992-09-30

Abstract

A self-propelled aquatic craft adapted for towing an individual through water comprised of an internal combustion engine drive connected to a propeller with a generally cylindrical guard member surrounding the propeller in which a chamber is formed between generally concentric inner and outer surfaces of the guard member and which serves as the exhaust chamber whereby the exhaust from the engine is muffled and cooled before being discharged into the water at a point beneath the individual being towed. The pressure in the exhaust chamber is applied to the surface of the fuel in the fuel tank to provide a positive fuel feed to the engine while preventing moisture in the exhaust from entering into the fuel tank.

Description

United States Patent 11 1 1111 3,908,578

Buelk 1 Sept. 30, 1975 [54] EXHAUST SYSTEMS FOR AQUATIC CRAFT 3,548,778 12/1970 Romunoff 1 15/70 3,630,165 12 1971 Bott 115 6.1 [75] Inventor Egge" Buelk Hamburg Germany 3,763.817 10i1973 Fran c i: 115/61 [73] Assignee: RockwellInternationalCorporation,

Pi b h p Primary Evaminer-Trygve M. Blix Assistant E.\'aminer.Galen L. Barefoot [22] Filed: June 6, 1973 21 Appl. NO.I 367,616 ABSTRACT A self-propelled aquatic craft adapted for towing an individual through water comprised of an internal [52] US. Cl. 115/6.1, 1 15/42, 1118517309, Combustion engine drive Connected to a propeller with 2 a generally cylindrical guard member surrounding the 2: gi propeller in which a chamber is formed between gen. 1 l g T H39 6 d l23/l36; erally concentric inner and outer surfaces of the guard member and which serves as the exhaust chamber whereby the exhaust from the engine is muffled and [56] References Cned cooled before being discharged into the water at 21 UNITED STATES PATENTS point beneath the individual being towed. The pres- 1,953 8()8 4/1934 Kenncweg 1. 123/136 sure in the exhaust chamber is applied to the surface 3.708.759 /1955 smlwn 4 I/6-1 of the fuel in the fuel tank to provide a positive fuel 3-l05-353 10/1963 Schulz 1157/14 feed to the engine while preventing moisture in the ex- 3249083 5/1966 gens 115/1 A haust from entering into the fuel tank. 3,406,653 10/1968 Mela 1 1 1 115/70 3,476,070 11/1969 Austen 115/42 2 Claims, 7 Drawing Figures NW as 3'11! .1, l

I 59 i 70 7 2o a2 94 lo 78 E I. 3 I 13 1 76 I00 63 122 48 4s so as U.S. Patent Sept. 30,1975 Sheet 1 of 3 3,908,578

US. Patent Sept. 30,1975 Sheet 2 of3 3,908,578

Sheet 3 of 3 Sept. 30,1975

,U.S. Patent BACKGROUND AND DISCUSSION OF PRIOR ART This invention relates to exhaust systems for internal combustion powered aquatic craft adapted for towing individuals through the water at or just beneath its surface. In such craft apropeller is usually driven by the engine to provide the motive force and a guard surrounding the propeller may be provided as shown for example in U.S. Pat. Nos. 2,708,750, 3,358,635 to prevent any part of the individual being towed from coming into contact with the rotating propeller blades. Also as taught in Pat. Nos. 2,708,759 and 3,630,165 it is necessary to provide an exhaust chamber not only to assist in muffling the exhaust noise but to cool the exhaust gases and to provide means to discharge exhaust into the water without backflow of water into the engine. In the prior art devices of this kind the exhaust chambers are separate and distinct elements and are often bulky and contribute significantly to the weight of the craft. Such craft are often operated and must be handled both in and out of the water by individuals and it is therefore important that their weight and size be held to a minimum. Also the weight and bulk of the prior art exhaust systems of such craft served to reduce the speed of movement through the water obtainable from an engine of a given size.

As a means of reducing size and weight and minimizing the cost of these craft the conventional fuel pump may be eliminated. In such cases it is desirable to provide a positive feed pressure on the fuel to insure its flow to the engine by applying the exhaust pressure to the surface of the fuel as shown for example in U.S. Pat. No. 3,630,165. In such arrangements however since the exhaust from the engine contains significant quantities of moisture in form of water or water vapor, the fuelbecomes contaminated with water resulting manfunctioning of the engine.

SUMMARY AND OBJECTS OF INVENTION In the present invention the disadvantages of the prior art are overcome by combining the exhaust chamber with the guard member around the propeller. The guard member is comprised of spaced inner and outer walls to form a chamber which serves as an exhaust chamber. Thus not only is the weight and bulk reduced from those of the prior art but the exhaust gases are muffled and are efficiently cooled so they may be discharged directly beneath the person being towed.

Also according to the instant invention passage means is provided between the exhaust chamber and the fuel tank to apply exhaust pressure to the fuel and in which passage is located means to prevent moisture from flowing into the fuel tank.

Accordingly, it is an object of the present invention to provide an aquatic towing craft which is compact, of minimum size and weight and from which maximum Speed can be obtained from a given size engine. It is another object to provide an exhaust system in which the exhaust chamber is formed in the guard member surrounding the propeller whereby the exhaust is effectively muffled and cooled prior to its discharge into the water. Another object is to provide an aquatic towing craft in which the exhaust is effectively cooled before dischargedat the lowest possible point beneath the individual being towed. A further object is to provide an exhaust system for internal combustion engines in which the exhaust pressure is utilized to provide a positive fuel feed to the engine and in which means are provided to prevent moisture in the exhaust from contaminating the fuel.

DESCRIPTION OF THE DRAWINGS FIG. lis a side view in vertical cross section of an aquatic craft embodying the invention described herein. I

FIG. 2 is a top plan view of the device shown in FIG. 1 with the housing enclosing the fuel and air chambers removed.

FIG. 3 is a view from the rear of the craft shown in FIG. 1 showing only the portion of the propeller guard member which contains the guide vanes.

FIG. 3A is a view along lines 3A-3A of FIG. 3 showing homing vanes in cross section.

FIG. 4 is a Side view showing the craft embodying the present invention propelling an individual through the water.

FIGS. 5 and 6 is a view from above showing the craft of the instant invention propelling an individual through the water.

DESCRIPTION OF THE INVENTION Referring to FIG. 1 of the drawings, an internal combustion engine generally designated by the numeral 10 has a main body portion 12 shown partially in section and which includes a cylinder 13. Piston 14 is reciprocally mounted in cylinder 13 which encloses combustion chamber 15. Housing 16 encloses a conventional recoil starter the handle of which is shown at 18. Also enclosed within housing 16 is a magneto which produces an electrical impulse which by means of conductor 22 is conducted to the spark plug 20 located in the top of cylinder 13. The junction of the conductor 22 and spark plug 20 is covered by a water tight rubber cap 17 to prevent moisture from short circuiting the spark plug. Since the recoil starter and magneto are conventional and function in a manner which is well known in the art detailed showings and descriptions thereof are not thought to be necessary.

As best shown in FIG. 2 a carburetor 24 is mounted on engine 10 in such a manner that when in operation, fuel/air mixture from the carburetor flows through passage 26 (FIG. 1) in body portion 12 and inlet passage 28 in cylinder 13. Secured to carburetor 24 is a valve block 30 to which

flow lines

32, 34 and 36 are connected in a manner and for a purpose which will hereinafter appear.

Integrally formed on the body portion 12 and extending rearwardly therefrom is a shaft housing 40 in which drive shaft 42 is journalled and on the rear end of which is secured propeller 44 for rotation therewith. A generally cylindrically shaped propeller shroud 46 made up of a forward shroud member 48 and rear shroud member 50 has an internal cylindrical wall 52 and a generally cylindrical outer wall 53 which is generally concentric to and spaced from wall 52 to form annular exhaust chamber 56 extending circumferentially around wall 52 between

walls

52 and 53.

Circumferentially spaced screws 58 shown in dotted lines serve to secure shroud member 50 to shroud member 48, and a plurality of circumferentially spaced vanes 54 extending between main body 12 and shroud member 48 rigidly supports shroud 46 to the rear of engine 10 and in axially alignment with shaft 42. Exhaust port 29 connects the interior of cylinder 13 with exhaust chamber 56.

As shown in FIG. 1, port 60 connects the bottom of exhaust chamber 56 with exhaust discharge passage 62 to allow discharge of the exhaust gases from exhaust chamber 56. Check valve 64 is biased by spring 66 to normally close port 60, the bias of the spring being such to allow the valve 64 to open under the pressure of exhaust being discharged into chamber 56 from engine but to close valve 64 when the pressure in chamber 56 is insufficient to prevent ingress of water through passage 62.

A combined air and fuel tank, generally indicated by the numeral 68, is divided into a forwardly disposed air chamber 70 and a rearwardly disposed fuel tank 72 which are separated from each other by double walls 74. Brackets 76 formed on either side of the top of shroud member 46 serve to rigidly support the rear portion of tank 68 by means of screws 78 threaded into the sides of the tank 68. In addition to a function and purpose to be hereinafter described, one end of each two handles 80 is secured respectively to one side of the front end of tank 68 by means of bolts 82, the other end of each handle being secured to the bottom of engine 10 by means of screws 84 to thereby rigidly support the front end of tank 68.

An elongated tube 86 is sealingly mounted on tank 68 by means of cap 90 threaded on to boss 92 on the exterior of tank 68. An internal passage 88 extending the length of tube 86 connects the chamber 70 with the atmosphere. Air supply tube 94 passes through the bottom wall of tank 68 and has one end connected to the carburetor to provide a supply of air to the carburetor from chamber 70. Within chamber 70 the other end of air supply tank 94 is curved so it will terminate near the top of the left side wall of tank 68 when the craft of FIG. 1 is viewed from the top by a person facing the front end thereof. By this arrangement the intake end of tube 94 is displaced from the discharge end of tube 86 so that any water which might accidentally be taken into the intake end of tube 86 will not be discharged directly into the intake end of tube 94 but instead will drop to the floor of the inside of tank 70 where it cannot enter tube 94 since its intake end is located near to top of the interior of the tank. A seal betwen tube 94 and the floor of tank 70 where it passes therethrough prevents leakage of water into tank 70 along the exterior of tube 94.

As shown in FIGS. 1 and 2 one end of each of the

flow lines

32, 34 and 36 is connected to valve block 30. The other end of flow line 34 is connected to a fitting 98 which extends through the floor of chamber 72 to connect the fuel supply to valve block 30. The other end of line 32 is connected to one end of a hollow tube 100 which extends through and is sealed with respect to the floor of chamber 72 on the side thereof opposite fitting 98, the fitting 98 and tube 100 being spaced from each other and located on opposite sides of chamber 72. The other end of tube 100 extends to a point just beneath the fuel tank cap 102 threaded onto boss 104 located on the top of fuel tank 72. Thus the interior of fuel tank 70 is connected at a point above the surface of the fuel to valve block 30. The upper end of tube 100 is positioned close to the internal surface of the boss 104 so fuel may be funneled into the fuel chamber without danger of any getting into tube 100.

FIG. 2 shows the top portion of wall 53 of shroud 46 partially broken away to expose exhaust chamber 56. Two vertical walls 109 and 111 form a channel 113 connecting exhaust port 29 with chamber 56. An orifice or passage 106 through wall 53 communicates with chamber 56. The end of line 36 remote from valve block 30 is connected to fitting 107 in wall 53 to connect line 36 to orifice 106 and chamber 56. Interiorly of valve block 30 to the line 36 is connect to line 32 and line 34 is connected to the mixing chamber of the carburetor 24. Thus fuel in tank 72 is connected to the carburetor and the exhaust chamber 56 is connected to the space above the surface of the fuel in fuel tank 72. By means of this arrangement the pressure of the exhaust in exhaust chamber 56 is applied to the surface of the fuel and forces the fuel through line 34 into carburetor 24, thus eliminating the need for a pump to pump fuel from the tank 72 to the carburetor 24. In starting, if the fuel in the tank 72 is not forced by gravity into the carburetor the engine may be turned over a few times by operating the recoil starter which will serve to apply sufficient pressure to the surface of the fuel through exhaust chamber 56 and

lines

32 and 36 to supply fuel to the carburetor thru line 34. Alternatively, the craft may be temporarily tipped so that some of the fuel is taken into the tube and fed to the carburetor. A sponge-like, resilient, porous element 115 located in space between the wall 111 and wall 53 serves to prevent moisture carried by the exhaust from getting into the fuel tank through

lines

34 and 36 in a manner which will be hereinafter more fully explained. In the lower portion of chamber 56, a U-shaped metal screenlike support member 63 having a relatively open mesh is supported between

walls

52 and 53 in partially surrounding relationship to port 60. Element 65, made of soft, resilient, porous material in the lower portion of chamber 56 is generally U-shaped in form and has its legs straddling the support member 63. Element 65 serves to muffle the exhaust to reduce the noise level while permitting free discharge of the exhaust through port 60. Support member 63 serves to support material 65 and hold it in place in partially surrounding relationship to port 60.

In order to prevent fuel lock within the carburetor the float chamber of the carburetor is vented to chamber 70 by means of tube 108 which connects to the hollow end tube 109. Tube 109 extends through and its exterior is sealed with respect to the floor of chamber 70. The upper end of tube 109 terminates near the top of chamber 70 to insure that any water on the floor of chamber 70 will not get into the carburetor.

Flow lines

32, 34, 36 and tube 108 are preferably made of some suitable flexible material which does not deteriorate and is otherwise unaffected by fresh or salt water, gasoline or the exhaust from the engine 10.

Valve knob 110 is connected to a fuel valve inside the valve block 30 operable to connect or disconnect line 34 with the mixing chamber of carburetor 24. Thus the fuel supply may be interrupted or established by rotating knob 110. Handle 112 is connected to a throttle valve located within the carburetor to control the supply of fuel/air mixture from the carburetor to cylinder 13 through inlet port 28. As viewed in FIG. 2, movement of throttle handle 112 to the left increases the supply of fuel/air mixture to the cylinder 13 and therefore the speed of the engine while movement of the handle 112 to the right has the opposite effect. Each end of a U-shaped hand control lever 114 is respectively pivotally connected to a respective control handle 80. Rod 116 connects the lever 114 with throttle hand 112 so that manipulation of the control lever changes the position of the throttle valve handle 112. Spring 118 tensioned between handle 1 12 and the body of engine biases the throttle to idle position.

FIG. 3 is a view from the rear of the craft showing the rear of vane cage 120 which consists of an outer circular wall 122 and a hub 124 connected together by a plurality of radially extending vanes 126. Vane cage 120 is press fitted or otherwise secured to the rear of shroud member 46 so that the inner surface of outer wall 122 is an extension of inner surface 52 of shroud member 46. It should be noted that shroud member 46, vanes 54 and vane cage 120 act to prevent accidental contact with the propeller 44 from any direction by the person being towed while

vanes

54 and 126 allow a free flow of water into and away from the propeller44. One or more of the substantially vertically oriented vanes of vane cage 120 have tail portions formed at an angle with respect to the direction of flow of water through the shroud 46. Such vanes are indicated at 126a in FIG. 3 and FIG. 3a. As shown these vanes have tail portions lb formed at an angle with respect to the main body of vanes 126a. When the craft of the instant invention is operating and proceeding through water, water will be flowing through vane cage 120 and in the absence of directional control by the person being towed, the water flowing through vane cage 120 will react on the surfaces of tail portions 1261; to cause the craft to move in a circular path having a relatively fixed arc of curvature.

In operation, as shown in FIGS. 4 and 5 the handles 80 are grasped from behind the craft by the person being towed in such a manner that the craft is held in a position between the arms of the person. The

tanks

70 and 72 are of a size to provide a buoyancy sufficient to support in water the weight of the engine and the other non-buoyant parts of the craft and to supply some additional buoying force. Depending on the weight of the person being towed, it may be desirable to tilt the craft upwardly at a slight angle to the horizontal as shown in FIG. 4 which will provide a slight vertical buoying force as the craft proceeds through the water which force will be in addition to the buoying force supplied by the

tanks

70 and 72. When the handles 80 are grasped by the person being towed the speed control lever is easily manipulated by the person to vary the speed of the engine. Movement of the lever 114 to the left in FIG. 1 increases the speed while in reverse movement under the influence of spring 118 decreases the speed.

It has been found that with the control handles 80 located at the forward portion of the craft ease of maneuver and directional control of the craft is greatly facilitated resulting in considerable improvement in the ability to control the direction of the movement of the craft over prior art devices utilizing handles located to the rear of the craft. In both cases the body of the swimmer in effect acts as the rudder and in order to turn the craft the body must be oriented at an angle with respect to the craft. It has been found that with the handles located at the forward end of the craft it takes much less effort to point the craft and to angularly orient it with respect to the body of the person being towed. Also, by use of the instant invention the craft may be easily oriented in a downward direction to cause it to submerge below the surface of the water to the extent permitted by the length of the snorkle tube 86. With handles located to the rear of the craft, it would be difficult for an ordinary person to point the craft downwardly as is necessary to cause it to submerge. However, with the handles located forwardly, this is easily accomplished with very little exertion on the part of the person being towed.

With the handles held from the rear of the craft by the individual being towed as shown in FIGS. 4 and 5 the craft will be contained within the confines of the arms of the individual and the rear of the craft where the exhaust is discharged will be under the body of the individual. However, because the exhaust chamber of the instant invention is located in the shroud around the propeller the exhaust chamber has a large area exposed to water making it an efficient heat exhanger. Thus, not only is the hot exhaust from the engine effectively cooled, it is discharged at the lower-most point on the craft at a point remote from the body of the individual.

As explained above during operation the exhaust pressure in chamber 56 is transmitted to the surface of the fuel in tank 72 by means of orifice 108 and

flow lines

36 and 32. Moisture in the form of water and water vapor is contained in the exhaust which is emitted from the cylinder or combustion chamber 15 of the engine in a series of pulsations, each pulsation consisting of a rise and decay of pressure. The rise in pressure is sufficiently rapid to carry the particles of moisture toward the fuel chamber while the decay of pressure is at a slower rate and may be insufficient to carry the particles of moisture in the opposite direction resulting eventually in an accumulation of water in the fuel tank. Also, as the fuel is used there will be a net flow of moisture laden exhaust from the feed tank 72. The spongelike element 1 15 to some degree acts as a filter to physically entrap and inhibit the flow of moisture therethrough but its main effect is to damp the exhaust pressure pulsations in the

flow lines

36 and 32 and reduce their magnitudes to a point where the rise in pressure is insufficient to carry the relatively heavy moisture particles toward the fuel tank 70. Thus by the filter and pressure damping effect of the element moisture is prevented from entering fuel tank 7 2.

Since the entirety of the craft of the instant invention is contained within the arms of the person being towed it is important that its size be held to a minimum. This is accomplished by the compact and functional arrangement of the elements of the craft of the instant invention in which the propeller and the shroud member are aligned with and located to the rear of the engine with the air and fuel chambers contained within one enclosure which is secured to the top of the engine and shroud member with the air chamber positioned over the engine and forwardly of the fuel tank which in turn is positioned over the shroud member. Since the air chamber and snorkle are located at the forward end of the craft, remote from the person being towed, such an arrangement provides a particularly compact unit with a minimum of obstruction to the vision of the person being towed.

In the event the person being towed inadvertently loses his grip of the handles 80 or deliberately releases them, the reaction of the water flowing through vane cage against the tail b 126a of vanes 126a will cause the craft to circle in a constant arc of curvature about a relatively fixed center so that it will return to substantially the point at which it was released and therefore is easily retrieved. The vanes 126b impart a constant turning effort to the craft when in operation; however the magnitude of this turning effort is such as to not be noticeable to the person being towed when the craft is controlled by such person in the manner herein described.

The instant invention provides a craft which is safe, easily maneuverable and which does not interfere with the vision of the person being towed, and is therefore particularly useful not only for recreational but also for functional purposes such as lifesaving procedures and as a scuba diver assist.

What is claimed and desired to be secured by Letters patent is:

1. A unitary self powered craft for propelling an individual through water at or near its surface comprising; an internal combustion engine having an exhaust port to conduct the flow of exhaust gas from said engine, propeller means located to the rear of said engine and near the rear of said craft and drive connected to said engine, said propeller being mounted for rotation about an axis substantially parallel to the direction of movement of said craft when being driven by said propeller, means on said craft adapted to be grasped by said individual from the rear of said craft whereby the rear portion of said craft is located between the arms of said individual and said propeller is located generally beneath said individual when so grasped, generally cylindrically shaped guard means mounted on said engine directly to the rear thereof and in surrounding relationship to said propeller to prevent accidental contact between the propeller and said individual, said guard means having generally cylindrically shaped concentric inner and outer walls forming an exhaust chamber therebetween which circumscribes said inner wall, means to connect said chamber to said exhaust port and means on said guard to permit discharge of said exhaust from said chamber while preventing entry of water into said chamber, said last mentioned means being located at substantially the lowermost point of said guard.

2. The craft defined in claim 1 in which said last mentioned means is a one-way valve in said outer wall.