Outboard motor for a boat

Abstract

 An outboard motor which can be mounted at the stem of a boat comprises a boat-side fuel tank (60) which is installed on the boat side, a fuel tank (29) on the outboard motor side which is installed near the front portion of an engine (21), a fuel pump (50) which supplies fuel to the engine, and a fuel changeover cock (37) which selectively switches the fuel tank on the boat side and the fuel tank on the outboard motor side to the fuel pump, and in which the fuel changeover cock (37) is installed below the fuel tank (29) on the outboard motor side. This results in short and compact piping of the fuel supply system. Moreover, the changeover valve can be switched so as to connect the fuel tanks thereby facilitating the filling of the tanks on the motor side.

Description

[0001] The present invention relates to the technical field of outboard motors of the type for which respective fuel tanks are provided on the boat side and on outboard motor side.

[0002] More specifically, the present invention relates to an outboard motor according to claim 1.

[0003] An outboard motor which can be detachably mounted at the stem of a small boat as a propulsion unit is well known in the state of the art. An engine is mounted in an upper portion of the propulsion unit. Various components such as a silencer, a carburetor, a starter case and a fuel pump, etc. are installed around the engine in a manner such as to provide a compact structure. The engine and auxiliary components are covered with an engine cover element which is called a cowling. In order to keep the overall size of the upper portion small, only a small fuel tank is provided on the outboard motor side. A system in which respective fuel tanks are provided on the boat side and inside the cowling is conventionally known for small outboard motors.

[0004] In the conventional systems, fuel is either sucked from the tank on the outboard motor side or from the fuel tank on the boat side. Accordingly, a fuel inlet is provided on the outboard motor for filling the tank therein.

[0005] When a fuel tank is to be installed inside a cowling and fuel is to be supplied from the boat side and the outboard motor side, there are various space restrictions because of the arrangement of the engine, a fuel pump, a carburetor, a changeover cock, etc. The fuel piping which connects these elements is arranged all around the engine. Thus, there are problems in respect of compactness and ease of installation.

[0006] Accordingly, the invention aims at providing an outboard motor wherein the piping of the fuel supplying system is short and compact.

[0007] This technical problem is solved by an outboard motor having the features of claim 1.

[0008] Further, in order to make a supplementary supply of fuel to the fuel tank on the outboard motor side, it is necessary to remove the cowling and to pour fuel which is contained in a supplementary supply container into the fuel tank, and there are therefore the problems that making a supplementary supply is troublesome and that it is necessary to make supplementary supply containers available.

[0009] In order to overcome these disadvantages, the fuel changeover cock is adapted to connect the fuel tank on the boat side and the fuel tank on the outboard motor side, and by an auxiliary fuel pump for supporting fuel exchange between said tanks. Moreover, an auxiliary fuel pump is provided for supporting fuel transfer between the tanks.

[0010] Further advantageous embodiments are laid down in the subclaims.

[0011] The invention will be described hereinafter in greater detail by means of example with respect to the accompanying drawings.

Fig. 1 is a side view of one form of practice of an outboard motor according to the invention.

Fig. 2 is a vertical section of Fig. 1.

Fig. 3 is an enlarged cross-section of the upper portion of Fig. 2.

Fig. 4 is a front view of the engine of Fig. 3.

Fig. 5 Fig. 5(A) is a rear view of the engine of Fig. 3, and Fig. 5(B) is an enlarged cross-section of portion X of Fig. 5(A).

Fig. 6 is a bottom view of the engine of Fig. 3.

Fig. 7 is a cross-section showing the connection structure of a connector.

Fig. 8 is for the purpose of describing the operation of the above form of practice.

Fig. 9 is a schematic drawing which illustrates another form of practice of the fuel supply system of the invention.

[0012] Below, forms of practice of the present invention will be described with reference to the drawings. In the description of the drawings below, identical parts are indicated by identical numbers, and in some cases a description will be omitted. Also, in the description below, bow and stern mean portions described with reference to the direction of propulsion of a boat.

[0013] Fig. 1 is a side view of a 1st form of practice of an outboard motor according to the invention. An outboard motor 1 is provided with a clamp bracket 3 which can be detachably mounted on the stern of a boat 2, a swivel bracket 6 which is supported via a horizontal shaft 5 on the clamp bracket 3 in a manner permitting it to pivot upward and downward and a propulsion unit 7 which is supported by the swivel bracket 6 in a manner permitting horizontally swinging. The propulsion unit 7 has an upper case 9 which is rotatably supported by the swivel bracket 6, and a lower case 10 is fitted to the bottom portion of the upper case 9, so, overall, constituting a casing. A propeller 11 is installed in the lower case 10, a bottom cowling 12, forming a cover element for the engine, is mounted on the upper portion of the upper case 9, and a top cowling 13 is detachably fitted on the bottom cowling 12.

[0014] A boat-side fuel tank 60 is installed on the boat 2 side, and it is connected to the outboard motor 1 via a manually actuated pump 61 and a fuel supply pipe 55. 15 indicates a starter handle, 16 a steering handle, 17 a cooling water take-in port, and 19 the water surface.

[0015] Fig. 2 shows a vertical section of Fig. 1. The upper case 9 is formed in the shape of a tube, an engine connection member 9a which spreads in a dish shape is formed at its top portion, a lower case connection member 9c is formed at its bottom portion, and a small-diameter tubular portion 9b is formed between the two connection members 9a and 9c. The swivel bracket 6 is fitted to the top and bottom of this tubular portion 9b via rubber mounts 20, and the upper case 9 is rotatably supported by the swivel bracket 6.

[0016] An engine 21 is connected to the engine connection member 9a of the upper case 9. The engine 21 is, for example, a single-cylinder 4-cycle engine, and it is provided with a horizontally disposed cylinder 22 and a vertically disposed crankshaft 23. A starter case 25, an intake manifold 26, a carburetor 27 and an outboard-motor-side fuel tank 29, etc. are installed around the engine 21. A drive shaft 30 is vertically installed inside the upper case 9 and lower case 10, its upper end is connected to the crankshaft 23, and its lower end is connected via a bevel gear 31 to a propeller shaft 32. Further, a shift rod 33 and a cooling water supply pipe 35 are vertically installed in the upper case 9, and the lower end of the cooling water supply pipe 35 is connected to a cooling water pump 36. In this form of practice, a fuel tank is also provided in the boat.

[0017] Next, a detailed description of Fig. 2 will be given with reference to Figs. 3-8. Fig. 3 is an enlarged cross-section of the upper part of Fig. 2, Fig. 4 is a front view of the engine of Fig. 3, Fig. 5 (A) is a rear view of the engine of Fig. 3. 5 (B) is an enlarged cross-section of portion X of Fig. 5 (A). Fig. 6 is a bottom view of the engine of Fig. 3, Fig. 7 is a cross-sectional view showing the connection structure of a connector, and Fig. 8 is for the purpose of describing the operation.

[0018] In Fig. 3, the bottom cowling 12 is fitted to the engine connection member 9a of the upper case 9 by means of bolts 14. The engine 21 consists of a cylinder head 21a, a head cover 21b, a cylinder case 21c and a crankcase 21d, which also serves as an oil pan, and it has a piston 21e which is connected to the crankshaft 23, an intake valve 21f, an exhaust valve 21g and an exhaust passage 21h. The intake port 26a of the intake manifold 26 opens downward.

[0019] Below the fuel tank 29, a fuel changeover cock 37 constituted by a three-way changeover valve is installed on the bottom surface of the bottom cowling 12, and it is possible to effect changeover of the fuel supply from the boat-side and the outboard-motor-side fuel tank by means of a changeover lever 37a. The changeover lever 37a extends through the bottom cowling 12 to the outside of the outboard motor casing. It is arranged at a lower portion thereof on or close to the front side of the outboard motor. Above the fuel changeover cock 37, a connector 39 for connection of a pipe from the boat-side fuel tank is mounted on the front surface of the bottom cowling 12. A push pin 39a and an engagement pin 39b are provided on this connector 39. The connector 39 is arranged close to the changeover cock 37 and lever 37a so as to keep the piping therebetween short and compact.

[0020] As shown in Fig. 7, the connector 39 can be connected to a connector 56 which is fitted to the end of a fuel supply pipe 55 of the fuel tank on the boat side. This connector 56 has inside it a ball valve 56b which is loaded by a spring 56a, a valve seat 56c for the ball valve 56b and an engagement hole 56d in which the engagement pin 39b can be engaged, and it has a hook 56e which retains the engagement pin 39b. When the connector 56 is connected to the connector 39, the push pin 39a pushes the ball valve 56b, so allowing fuel to flow.

[0021] As shown in Figs. 3-6, the fuel tank 29 is installed in close proximity to the front surface of the engine body (21c, 21d), its upper portion extends upward from the side surface of the starter case 25, projects at the upper surface of the top cowling 13 and is pushed against the top cowling 13 via packing 40 for sealing, an oil supply cap 41 is screwed onto the top end of the fuel tank 29, and an air bleed cap 42 is screwed onto the oil supply cap 41.

[0022] As shown in Figs. 4-6, two brackets 29a and 29b on the engine body (21c, 21d) side are formed integrally with a side surface of the fuel tank 29, and one bracket 29c is integrally formed at the bottom surface. Further, there are also brackets 25a and 25b formed integrally with opposite side surfaces of the starter case 25, pipes 43a and 43b are formed integrally with the cylinder case 21c, and a pipe 43c is formed integrally with the crankcase 21d.

[0023] The bracket 25a and 25b at the sides of the starter case 25 and the side-surface brackets 29a and 29b of the fuel tank 29 are brought into contact and fixed to the pipes 43a and 43b on the engine body side by bolts 45, and the bracket 29c at the bottom surface of the fuel tank 29 is fixed to the pipe 43c on the engine body side by a bolt 45. In this fixing structure, as shown in Fig. 5, transmission of engine vibration to the fuel tank 29 is prevented by fitting a collar 46 between the bolt 45 and pipe 43b and providing bushes 47 of elastic material such as rubber, etc. between the bracket 25b and the bracket 29b and between the bracket 29b and the pipe 43c.

[0024] A fuel supply port 29d is formed at the bottom surface of the fuel tank 29. One inlet port of the fuel changeover cock 37 is connected to the fuel supply port 29d by a pipe 49a, the other input port is connected to the connector 39 by a pipe 49b, the outlet port is connected by a pipe 49c to a fuel pump 50 (Fig. 5), and the fuel pump 50 is connected by a pipe 49d to the carburetor 27. This fuel pump 50 is driven by rotation of the crankshaft 23.

[0025] In Fig. 3, cold air is taken in via an air take-in port 53 between the upper case 9 and the bottom cowling 12, and the fuel tank 29 is cooled, since the cold air passes around the fuel tank 29, as indicated by the arrows in the drawing. Cold air from the air take-in port 53 between the upper case 9 and bottom cowling 12 is also taken into the intake port 26a. In this process, the intake port 26a can take in fresh air easily, since it opens downward. An air bleed port 51 which faces the carburetor 27 is formed in the top surface of the top cowling 13, and a cover 52 is fitted in a manner such that it covers this air bleed port 51, thus making it possible to exhaust air from inside the cowlings 12 and 13 but at the same time to prevent infiltration of water.

[0026] The operation of this form of practice with the structure described above will be described with reference to Fig. 8. In Fig. 8, the auxiliary fuel pump is the abovenoted manually actuated fuel pump 61, and the main fuel pump is the engine drive fuel pump 50.

[0027] As illustrated in Fig. 8 (A), when the fuel changeover cock 37 is switched to the position in which the fuel tank 60 on the boat side and the fuel pump 50 are connected and the fuel tank 29 on the outboard motor side is cut off, fuel is supplied to the carburetor 27 by means of the fuel tank 60 on the boat side, auxiliary fuel pump 61 (used only at the time of start-up), fuel supply pipe 55, connectors 56 and 39, pipe 49b, fuel changeover cock 37, pipe 49c, fuel pump 50 and pipe 49d.

[0028] Further, as illustrated in Fig. 8 (B), when the fuel changeover cock 37 is switched to the position in which fuel tank 29 on the outboard motor side and the fuel pump 50 are connected and the fuel tank 60 on the boat side is cut off, fuel is supplied to the carburetor 27 by means of the fuel tank 29 on the outboard motor side, pipe 49a, fuel changeover cock 37, pipe 49c, fuel pump 50 and pipe 49d. At this time, the air bleed cap 42 is loosened so as to let the interior of the fuel tank 29 on the outboard motor side communicate with the atmosphere.

[0029] In this form of practice, since the fuel tank 29 on the outboard motor side is installed at the front part of the engine and the fuel changeover cock 37 and connector 39 are installed below the fuel tank 29, it is possible to instal the fuel supply parts compactly and to make the fuel piping short.

[0030] Fig. 9 is a schematic drawing which illustrates another form of practice of the fuel supply system of the invention. The abovedescribed fuel tank 60 on the boat side, auxiliary fuel pump (manually actuated fuel pump) 61, connectors 56 and 39, fuel changeover cock 37, fuel tank 29 on the outboard motor side, air bleed cap 42, main fuel pump (engine drive fuel pump) 50 and carburetor 27 are shown in Fig. 9.

[0031] In this form of practice, a non-return valve 62 is installed on the downstream side of the auxiliary fuel pump 61, and the structure of the fuel changeover cock 37 is made such that the fuel tank 29 on the outboard motor side can be connected to the fuel tank 60 on the boat side and the main fuel pump 50. When, in a state in which the engine has stopped and the main fuel pump 50 has stopped, the air bleed cap 42 is loosened and the auxiliary fuel pump 61 is actuated, fuel of the fuel tank 60 on the boat side is supplied to the fuel tank 29 on the outboard motor side, thus making supplementary supply of fuel possible. The arrangement may also be that the non-return valve 62 is installed between the connector 39 and the fuel changeover cock 37.

[0032] Following the supplementary supply of fuel to the fuel tank 29 on the outboard motor side, once the air bleed cap 42 is closed, the interior of the fuel tank 29 on the outboard motor side goes to negative pressure accompanying engine drive and consumption of the fuel in the fuel tank 29 on the outboard motor side, and the fuel tank 29 on the outboard motor side can be automatically replenished with fuel which is in the fuel tank 60 on the boat side.

[0033] Although forms of practice of the invention have been described above, the invention is not limited to these, but it is possible to make a variety of modifications. For example, although, in the forms of practice described above, the description was given with reference to the example of a 4-cycle engine, application to a 2-cycle engine is possible too, and in this case the carburetor is located in the front portion of the engine.

[0034] In conclusion, in an outboard motor of the type wherein fuel tanks are provided on the boat side and on the outboard motor side, the fuel tank on the outboard motor side is located at the front portion of the engine and a fuel changeover cock and a connector are located below this fuel tank, it is possible to instal the fuel supply parts compactly and to make the fuel piping short. The fuel changeover cock can be installed by making use of the space inside a cover element.

[0035] Further, it is possible for supplementary supply of fuel to the fuel tank on the outboard motor side to be effected easily. This does not necessarily require that the changeover valve 37 is arranged below the fuel tank 29. It may also be arranged anywhere else on the outboard motor.

Claims

1. Outboard motor for a boat comprising

an engine (21) on the outboard motor side,

a fuel tank (60) adapted to be installed on the boat side,

a fuel tank (29) on the outboard motor side, which is installed close to a front portion of the engine (21),

a fuel pump (50) for supplying fuel to the engine (21), and

a fuel changeover cock (37) for selectively switching the fuel tank (29) on the outboard motor side and the fuel tank (60) on the boat side to the fuel pump (50),
wherein said fuel changeover cock (37) is installed below the fuel tank (29) on the outboard motor side.

2. Outboard motor according to claim 1, characterized in that the fuel changeover cock (37) is fixed to a cover element (12) which covers the engine (21).

3. Outboard motor according to claim 1 or 2, characterized in that said fuel changeover cock (37) is adapted to connect the fuel tank (60) on the boat side and the fuel tank (29) on the outboard motor side, and by an auxiliary fuel pump (61) for supporting fuel exchange between said tanks (29,60).

4. Outboard motor according to claim 2 or 3, characterized in that said changeover cock (37) comprises a changeover lever (37a) for switching said changeover cock (37), said changeover lever being arranged so as to extend through said cover element (12) to the outside of the casing of the outboard motor at a lower portion on the front side of the outboard motor.

5. Outboard motor according to one of claims 1 to 4, characterized in that a connector (39) for connecting a pipe (55) from the fuel tank (60) on the boat side to the changeover cock (37) is mounted on the front surface of the cover element (12).

6. Outboard motor according to claim 5, characterized in that said pipe (55) from the fuel tank (60) on the boat side is detachably coupled to said connector (39) by a connector (56) fitted on an end portion of said pipe (55), said connector (56) on said pipe (55) including a one-way valve (56b) and locking means (56e) for engagement with the connector (39) on the cover element (12).

7. Outboard motor according to one of claims 1 to 6, characterized in that means (29a,29b,29c) for supporting the fuel tank (29) on the outboard motor side on the engine are integrally formed on said tank (29), said supporting means (29a,29b,29c) being supported on said engine through elastic means (46,47).

8. Outboard motor according to one of claims 1 to 7, characterized in that an air take-in port (53) is provided in a bottom portion of the casing (9,12,13) of the outboard motor, said take-in port (53) being arranged substantially below the fuel tank (29) on the outboard motor side, and that the interior of the outboard motor is shaped so as to guide intake air to an intake port (26) of the engine (26,27), thereby passing said fuel tank (29).

9. Outboard motor according to one of claims 3 to 8, characterized in that a non-return valve (62) is installed downstream the auxiliary fuel pump (61).

10. Outboard motor according to claim 9, characterized in that said non-return valve (62) is arranged between the connector (39) and the fuel changeover cock (37).

Drawing