An outboard motor and boat

Abstract: At present, more rigid inflatable boats become incapacitated through the outboard motor becoming submerged than the boat capsizing. The present invention comprises an outboard motor (1) having a number of special features which prevent the ingress of water so that it can be operated underwater and a boat (10) also having a number of special features to be used together with the outboard motor (1). The features on the outboard motor (1) include means for creating a water-tight seal on the carburettor shaft mountings (24, 26); means for protecting the air intake of the carburettor against ingress of water (8, 9, 11, 13; 9, 14, 15); a bellows (28) coupled to and encapsulating the starter motor (5); a sealed housing (32) for the electrical system having a moisture-tight seal around each wire at the junction with the sealed housing; a one-way valve (22) disposed in the exhaust (6); and means for protecting the atmospheric vents (20, 21) against ingress of water. The features on the boat (10) include such an outboard motor (1) plus a ducted air intake (11,15) for the carburetter (2) passing through an air sump (9).

Description: The present invention relates to a boat having an outboard motor and, in particular, to an outboard motor designed to minimise the ingress of water when the motor is submerged, thereby enabling the motor to continue to operate under water. Outboard motors are often used to drive rigid inflatable boats. In high sea conditions, the boat may be capsized or the motor may become submerged. More boats become incapacitated through the motor becoming submerged than the boat capsizing. When a motor is submerged, water may enter through the exhaust, the air intake for the carburettor, the injection system, the atmospheric vents on the carburettor and exhaust, and the choke or throttle spindle shafts. This water may penetrate through to the starter motor and to the electrical circuits. Ingress of water via any of these routes will incapacitate the motor. It is necessary, in order to re-start the motor, to drain water from the motor, expunge contaminated fuel from the carburettors and fit dry spark plugs. In high seas or other adverse weather conditions, it is rarely possible to effectively drain the motor and fit dry spark plugs. Consequently, the boat must then be abandoned or towed to safety. Accordingly, many attempts have been made to seal the motor to prevent the cause of incapacitation. Initially, external covers with seals were provided for the motor. These are effective until the first maintainance or repair is executed on the motor, since the seals have then to be broken to provide access to the motor. Subsequent re-sealing is never as effective. Known preventive measures have also included an elongated air intake installation for the carburettor to the cover of the motor. Again, once the seals of the cover are broken, then such elongated air intake installations become ineffective. Another known measure comprises an elongated air intake installation located in the boat, so that its open end is disposed in a hood or cabin. Such installations though are not capable of effectively protecting the carburettor/injection system when the boat capsizes and furthermore does not provide effective protection when water penetrates the motor cover. None of the measures known to date effectively protect a motor in adverse conditions. Even the arrangement described in EP 0217671A is insufficient in some conditions. An aim of the present invention is therefore to provide a motor having a number of features which improve the chances of it running under water. Another aim of the present invention is to provide a boat having such a motor. According to the present invention there is provided an outboard motor comprising: at least one carburettor having a shaft and an air intake, at least one starter motor, an electrical system, an exhaust and a number of atmospheric vents; and air supply means for providing air to the or each air intake and for protecting said intake or intakes against ingress of water; the air supply means comprising a hollow space located below the air intake or intakes and having at least one air inlet and air supply tubing leading from the hollow space to a respective air intakes; characterised in that the motor further comprises: means for creating a water-tight seal on the mountings of the or each carburettor shaft; means for protecting the or each starter motor against ingress of water; a sealed housing for the electrical system having a moisture-tight seal around the or each wire at the junction with the sealed housing; a one-way valve disposed in the exhaust; means for protecting the atmospheric vents against ingress of water; and a hollow upstanding tubular structure comprising a roll bar open at an upper portion and forming an air supply duct in which is located the air inlet. Also, according to the present invention there is also provided a boat having such an outboard motor. A preferred embodiment of the present invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a partial schematic cross-section of an outboard motor, highlighting features of a preferred embodiment; Fig. 2 is a schematic cross-section of a rigid inflatable boat having an outboard motor according to the preferred embodiment; Fig. 3a is an enlargement of part A in Fig. 2; Fig. 3b is a view in the direction of arrow B in Fig. 2; Fig. 4 is a schematic partial cross-section of a carburettor according to the preferred embodiment; and Fig. 5 is an enlargement and partial cross-section of part of the carburettor shown in Fig. 4. As shown schematically in Figure 1, the present invention relates to a number of novel features which improve the chances of an outboard motor 1 operating even if submerged. The motor 1 includes the usual features such as carburettors 2 coupled to a manifold 3, pistons (not shown), spark plugs 4, connecting rods (not shown), starter motor 5 and through-propellor exhaust 6. In a preferred embodiment, there are three carburettors 2 and the air intake of each carburettor 2 is coupled to a common manifold 3. Each manifold 3 has a number of air intake tubes 7 extending downwardly therefrom. The length of the tubes 7 is chosen so as to allow the motor to turn on its support means yet not to be so long as to be an obstruction to persons within the boat. The tubes 7 are fabricated from known reinforced flexible pipes. Crushed pipes can result in either starving the carburettors of air or creating a crack in the pipe leading to leaks in the air installation system. Consequently the pipes are reinforced. However, the pipes need to be flexible to allow the motor 1 to be fitted and turned on its support means as desired. Accordingly the pipes are reinforced yet flexible. The air intake tubes 7 of each carburettor 2 extend downwardly to a common termination point 8 shown in Figures 2 and 3b. Each common termination point 8 comprises a plate having unions machine-turned therein to allow each of the tubes 7 to be screwed into a respective union. An air sump 9 for each motor 1 is located under the deck 29 of the boat 10 and each air sump 9 comprises a chamber forming an integral part of the hull design. Each of the tubes 7 communicates with the air sump 9 via the respective common termination point 8. The air sump 9 is located beneath the deck 29 of the boat so as to minimise any obstruction on the deck of the boat 10, which is particularly important in adverse weather conditions and at night. In order to provide air to the carburettors 2, each air sump 9 needs to be open to the atmosphere yet protected to prevent water ingress. As shown in Figure 2, the air sump 9 communicates with the atmosphere via a hollow roll frame 11 and a tube 12. Inlet vents 13 are provided in the top of the roll frame 11 to provide a through-flow of air. If the boat 10 capsizes or water splashes onto the roll frame 11, then any such water runs down the inside of the roll frame 11 and into the bottom of an air sump 9 but it is not drawn into the engine because the air sump is so large compared to the suction pressure of the engine. Also, the common termination point is located at the top of the respective air sump 9, remote from any water collected in the air sump 9. Each air sump 9 is provided with a sealable port 30, such as a screwed plug, thereby enabling excess water to be drained off as and when necessary. The inlet vents 13 in the roll frame 11 may be provided with a valve but this is usually not necessary as the above described air intake protection system is already quite adequate. Further measures designed to minimise the ingress of water to the motor are illustrated with reference to Figure 1 again. A motor requires a number of air passages in order to operate, for example the atmospheric vent 20 on the carburettor or the exhaust atmospheric vent 21, and these must also be sealed or protected. In the preferred embodiment, these vents 20, 21 are also each provided with a protection system (not shown) comprising ducting leading to a respective snorkel pipe with a one way valve at the open end and a grill cap. Each of these protection systems are merely a smaller version of that provided in the inlet tube. In each case the snorkel of the protection system may stand proud of the engine cowl or terminate within the engine cowl. Another passage requiring protection is the exhaust 6. Whilst the motor is running, the pressure of the exhaust gases prevents any water from rising into the engine part of the motor. If, the motor stops for any reason, or if the engine is just idling, then the back pressure created in the engine may be sufficient to siphon water into the engine. Accordingly, the exhaust 6 is also provided with a one-way valve system 22. The one-way valve 22 comprises a ball valve 33 disposed behind a grill 34 to ensure the ball of the ball valve is not lost. With all these measures provided on the air passages for allowing gases into and out of the engine, water can be prevented from reaching the engine. Consequently, additional measures designed to keep the spark plugs dry are not necessary as water should not be sucked into the engine by virtue of the aforementioned features. If, however, water does trickle into the engine, further measures can be taken. Figure 4 is a schematic cross-section of the carburettor 2. The carburettor 2 itself can be sealed relatively easily to prevent water seepage except by way of the carburettor shaft 23. Accordingly, the preferred embodiment of the present invention includes means for creating a water-tight seal on the shaft mountings. This water-tight seal means includes a compressed rubber cap 24 between the carburettor housing 25 and the throttle lever 36 and is fixed to the carburettor housing 25 yet permits the shaft 23 to rotate therein. At the other end of the shaft 23, there is provided an O-ring compression seal 26, preferably a neoprene seal, between the carburettor housing 25 and the spring 27 on the shaft 23. The seal 26 is fixed and does not rotate with the shaft 23. These measures enable the carburettor shaft 23 to rotate in the carburettor yet provide a water-tight seal over 78-80 degrees of rotational movement of the shaft 23. Similar measures are also provided on the choke spindle 37 of the choke 31. Thus a compressed cap 38 and an O-ring compression seal 39 are arranged as on the spindle 37. In the preferred embodiment, the electrical parts, eg. switches, of the engine are also disposed in a sealed housing 32. All of the wires going into or out of the sealed housing are sealed at the junction with the housing. This may be achieved by rubber bushings which are a known moisture protection measure. However, more preferably an hydrophobic moulding compound is used when malleable to be shaped around the wire junction and it is then cured to form a moisture tight seal. Hydrophobic compounds include acrylic resins. The starter motor 5 cannot be sealed with the rest of the electrical parts. Accordingly, the preferred embodiment of the present invention includes means for protecting the starter motor. When the starter motor runs, the air inside heats up and expands. If the outboard motor is submerged in water, the air temperature is lowered and the degree of expansion is reduced. In order to accommodate this change in volume, the preferred embodiment of the present invention includes a bellows-type structure 28. The bellows 28 expand and contract as and when necessary and also the expansion and contraction varies in accordance with the temperature surrounding the starter motor. The bellows 28 are attached to the top cover of the starter motor completely encapsulating it. This aspect of the present invention is also applicable to any type of engine, not just one disposed in an outboard motor. The combination of all these measures thus enables the motor to operate even if submerged. The advantages of such a motor can readily be appreciated in adverse sea conditions. The aforegoing description has been given by way of example only and it will be appreciated by a person skilled in the art that modifications may be made without departing from the scope of the invention. For example, the manifold 3 need not be used, the tubes 7 coming directly from each carburettor air intake.

Claims: An outboard motor (1) comprising: at least one carburettor (2) having a shaft (23) and an air intake (7), at least one starter motor (5), an electrical system, an exhaust (6) and a number of atmospheric vents (20, 21); and air supply means (8,9,11,13) for providing air to the or each air intake (7) and for protecting said intake or intakes (7) against ingress of water, the air supply means comprising a hollow space (9) located below the air intake or intakes (7) and having at least one air inlet (13) and air supply tubing leading from the hollow space (9) to a respective air intake (7); characterised in that the motor (1) further comprises: means (24, 26) for creating a water-tight seal on the mountings of the or each carburettor shaft (23); means for protecting the or each starter motor (5) against ingress of water; a sealed housing (32) for the electrical system having a moisture-tight seal around the or each wire at the junction with the sealed housing (32); a one-way valve (22) disposed in the exhaust (6); means for protecting the atmospheric vents (20,21) against ingress of water; and a hollow upstanding tubular structure comprising a roll bar (11) open at an upper portion and forming an air supply duct in which is located the air inlet (13). An outboard motor as claimed in claim 1, wherein the roll bar (11) has a substantially horizontal portion, the air inlet (13) being located in the substantially horizontal portion of the roll bar (11). An outboard motor as claimed in claim 2, wherein two air inlets (13) are provided in the substantially horizontal portion of the roll bar (11). An outboard motor as claimed in any one of the preceding claims, wherein the or each air inlet (13) is provided with a valve. An outboard motor as claimed in any one of the preceding claims, wherein said water-tight seal means on the or each carburettor shaft (23) comprises a compression cap (24) disposed on said shaft (23) between the carburettor housing (25) and the throttle lever (36) rocker arm and fixed with respect to said housing (25) and an O-ring compression seal (26) disposed on said shaft between the carburettor housing (25) and the shaft spring (27) and fixed with respect to said shaft (23). An outboard motor as claimed in claim 5, wherein said compression cap (24) is formed of rubber and said O-ring compression seal (26) is formed of neoprene. An outboard motor as claimed in any one of the preceding claims, wherein said moisture-tight seal around the or each wire comprises an hydrophobic compound formed around the or each wire at the junction with the sealed housing (32). An outboard motor as claimed in any one of the preceding claims, wherein said one-way exhaust valve (22) comprises a ball valve (33). An outboard motor as claimed in any one of the preceding claims, wherein said atmospheric vent protection means includes a snorkel with a one-way valve arranged at the open end of the snorkel. An outboard motor as claimed in any one of the preceding claims, wherein the or each carburettor is coupled to a manifold (3) and the or each tube (7) is connected to said manifold (3). An outboard motor as claimed in any one of the preceding claims, further comprising a choke (31) having means for creating a water-tight seal on the mountings of the choke shaft (37). An outboard motor as claimed in claim 6, wherein said water-tight seal means comprises a compression cap (38) disposed on said shaft (37) between the choke housing and the choke lever and an O-ring compression seal (39) disposed on said shaft (37) between the choke housing and the shaft spring. An outboard motor as claimed in any one of the preceding claims, wherein said means for protecting the starter motor (5) comprises a bellows structure (28) attached to the top plate of the starter motor (5) and encapsulating the starter motor (5). A boat having an outboard motor as claimed in any one of claims 1 to 13. A boat as claimed in claim 14, wherein said hollow space (9) is disposed beneath the deck (29) of the boat (10).

Inventors: GLEN ROBERT D, GLEN, ROBERT D
Applicants: BARRUS E P LTD, E.P. BARRUS LIMITED
Application year: 1991
Main classification: F02B61
IPC codes: F02B61, F02M35