Outboard motor with a catalytic system

Abstract: An outboard motor with a catalytic system for an engine which has a crankshaft disposed vertically, wherein an exhaust passage in communication with an exhaust port is formed in the side wall of an engine body, and at least one catalyst is disposed in parallel to the exhaust gas stream.

Description: This invention relates to an outboard motor with a catalytic system for an engine which has a crankshaft disposed vertically. An outboard motor mounted on a small marine vessel is generally configured such that an upper case and an exhaust guide are connected with the upper side of a lower case, an engine is supported on the exhaust guide and secured thereto, the engine is covered with a cowling which in turn drives a propulsion unit to rotate and the exhaust from the engine is passed through an exhaust passage formed vertically in the side wall of the engine body, via an upper case and a lower case, and then discharged into sea water. Recently, in such an engine for an outboard motor, it has been proposed that a catalyst is provided in the exhaust passage, in view of clarification of exhaust gas. In JP-A-7-189671, for example, it is disclosed that a catalyst is disposed in an upper case below an engine, and in JP-A-4-260893 an catalyst provided in an exhaust passage in the side surface of the engine body. US 5 439 651 A and US 5 743 774 A also show outboard motors where the catalyst is located below the engine. However, in such a way above as the catalytic converter being disposed in the upper case below the engine, a bypass must be employed in order to locate the exhaust passage above the sea level for avoiding the catalytic converter from contacting seawater. It will be difficult to provide the bypass within a limited space of the cowling. Particularly, in 4-stroke cycle engines it is difficult to provide a bypass due to the large volume of the cylinder head having a valve actuating mechanism. To overcome this problem, in a manner such that a catalytic device is provided in the exhaust passage on the side wall of the engine body, the catalytic device is positioned in the direction normal to the exhaust gas flow, thereby resulting in the problems of the increase in the volume of the catalytic device, damage to the catalyst, and fusion of support member for supporting the catalyst due to the increase in the temperature of the catalytic system located close to the exhaust gas outlet. Accordingly, it is an objective of the present invention to provide an outboard motor as indicated above allowing the catalytic device to be compact for mounting and to be improved in the cooling performance. According to the present invention, this objective is solved for an outboard motor as indicated above in that an exhaust passage in communication with an exhaust port is formed in the side wall of an engine body, and at least one catalyst is disposed in parallel to the exhaust gas stream and in a same level with regard to said exhaust port. Therefore, the invention of claim 1 is characterized in that, in an engine having a crankshaft disposed vertically for an outboard motor, an exhaust passage in communication with an exhaust port is formed in the side wall of an engine body, and catalysts are disposed in parallel to the exhaust gas stream, and in a same level with regard to said exhaust port. The invention of claim 2 is characterized in that said system comprises: a cylinder body defining said engine body; an exhaust outlet formed on an upper side wall of said cylinder body; an exhaust passage formed in the lower part of said cylinder body; at least one spacing plate secured so as to cover said exhaust outlet and exhaust passage; covers attached to said spacing plate; and an exhaust passage is formed between said spacing plate and cover. The invention of claim 3 is characterized in that two catalysts are arranged in parallel relationship to each other. The invention of claim 4 is characterized in that cooling water passages are formed in said spacing plate and cover. The invention of claim 5 is characterized in that said catalytic system comprises: a cylinder body and a cylinder head defining said engine body; an exhaust collection member secured on the upper side wall of said cylinder head so as to collect exhaust gas from said exhaust port; an exhaust pipe connected with said exhaust collection member and disposed horizontally, along the surface of said cylinder body; and another pipe connected with said exhaust pipe and disposed vertically along the surface of said cylinder body; and catalyst are disposed in said horizontally extending exhaust pipe and vertically extending exhaust pipe, respectively. The invention of claim 7 is characterized in that a cooling water passage is formed on the outer circumferences of said exhaust collection member and exhaust pipes. The invention of claim 10 is characterized in that said engine is a 4-stroke cycle engine. Other preferred embodiments of the present invention are laid down in further dependent claims. In the following, the present invention is explained in greater detail with respect to several embodiments thereof in conjunction with the accompanying drawings, wherein: Fig.1 is a side elevational view of an outboard motor applied with the invention; Fig.2 is a plan view of the engine in Fig.1; Fig.3 is a partially and horizontally cross sectional view of Fig.2, as seen from arrows of line A-A of Fig.4; Fig.4 is a sectional view, as seen from arrows of line B-B of Fig.3; Fig.5 is a side view, as seen from the arrow C in Fig.4, in which a guide member 55 and covers 47, 49 are removed; Fig.6 is a bottom view, as seen from the arrow D in the same manner; Fig.7 is a partially cross sectional view, as seen from arrows of line E-E of Fig.5; Fig.8 is a plan view of the engine in Fig. 1; and Fig.9 is a partially cross sectional view of the exhaust system shown in Fig.8. Figs.1 and 2 show an example of an outboard motor applied with this invention. Fig.1 is a side elevational view of an outboard motor, and Fig.2 is a plan view of the engine in Fig. 1. In the following description same reference numerals are used in the same structures in both drawings and the description therefor may be omitted. Referring to Fig.1, an outboard motor 1 comprises a clamp bracket 3 detachably mounted on the rear end (relative to advance direction) of a hull 2, a swivel bracket 5 pivoted up and down about a pivot axis 4 and supported by the clamp bracket 3, a steering bracket 6 allowing the swivel bracket 5 to rotate horizontally about its axis, and a propulsion unit 9 supported on the steering bracket 6 through a mount bracket 7. The propulsion unit 9 has an upper case 10 supported on the steering bracket 6. On the upper part of the upper case 10 are mounted an exhaust guide 12 which is a support member for supporting an engine 11, and a lower cowling 13 enclosing the lower part of the engine. An upper cowling (engine cover) 14 covering the upper part of the engine 11 is removably attached to the lower cowling 13. At the lower part of the upper case 10 is mounted a lower case 15, thereby, as a whole, a casing is configured. A cover member 16 is detachably mounted to the front part F of the engine cover 14. On both right and left sides of the cover member 16, air inlets 17 are opened, an air inlet 19 is also formed at the rear part R of the engine cover 14. In Fig.2, the engine 11 is a 4-cylinder, 4-stroke cycle engine 11 of water cooled type, in which a crankshaft 21, an exhaust camshaft 22, an intake camshaft 23 are disposed in an engine body 20 so as to pass through it vertically. A drive pulley 24 and a flywheel 25 are fixed on the upper part of the crankshaft 21, and driven pulleys 26, 27 are fixed on the camshafts 22, 23. The rotating movement of the drive pulley 24 is therefore transmitted to the driven pulleys 26, 27 through a belt 29. Four cylinders 41 a (line B-B, Fig.3) are vertically juxtaposed in the engine body 20. Four Intake pipes 30 are connected with the cylinders 41 a, respectively and are extended, with throttle bodies 31 provided at their intermediate positions, respectively, to a silencer 32 disposed in front of the engine 11, where they are gathered to connect each other There are provided fuel injection valves 33, a fuel pump 35, a thermostat 36, a starting motor 37, and a flywheel cover 38. A catalytic device 40 according to the invention is mounted by the exhaust side of the engine body 20. Figs.3 through 5 show an embodiment according to the invention: Fig.3 is a partially and horizontally cross sectional view of Fig.2, as seen from arrows of line A-A of Fig.4; Fig.4 is a sectional view, as seen from arrows of line B-B of Fig.3; Fig.5 is a side view, as seen from the arrow C in Fig.4, in which a guide member 55 and covers 47, 49 are removed; Fig.6 is a bottom view, as seen from the arrow D in the same manner and Fig.7 is a partially cross sectional view, as seen from arrows of line E-E of Fig.5. In Fig.3, the engine body 20 which is shown in Fig.2, is configured such that the cylinder body 41 is coupled to a cylinder head 42. In the cylinder body 41 four cylinders 41 a, exhaust collection member 41b and a water jacket 41c are formed. A piston 43 is slidably fitted in each cylinder 41 a. In the cylinder head 42, four exhaust ports 42a and a water jacket 42c are formed and an exhaust valve 44 actuated by an exhaust cam 22a is provided to engage each exhaust port 42a. The outlet of each exhaust port 42a is opened at the mating surface on the cylinder body 41 side, and the exhaust collection member 41 b is formed with an exhaust gas inlet 41 d, the cross section of which is longitudinal along up and down direction and with an exhaust outlet 41 e on the upper part of the side surface of the cylinder body 41. In the lower part of the cylinder body 41, as shown Fig.4, is formed an exhaust passage 45 which introduces exhaust gas to the exhaust guide 12 side (Fig.1), while, on the side surface of the cylinder body 41 are secured two spacing plates 46 which cover the exhaust collection member 12 and the exhaust passage 45. Those spacing plates 46 extend from the cylinder body 41 toward the cylinder head 42 and are formed with openings 46a, 46b in communication with an exhaust outlet 41e and the exhaust passage 45. An inner cover 47 is secured onto the spacing plates 46, resulting to form an exhaust passage 48 therebetween. An outer cover 49 is then secured onto the inner cover 47, resulting to form a cooling water passage 50 therebetween. On both sides of the spacing plates 46 are attached brackets 51, 52, between which two catalytic devices 53, 54 in a shape of cylinder are detachably interposed. As shown in Fig.4, a guide member 55 for directing the exhaust toward the opening 46b is attached on the lower bracket 52, while an air/fuel sensor 56 is mounted above the exhaust passage 48. At the lower part of the spacing plates 46, an exhaust temperature sensor 58 is provided for monitoring the temperature of the catalysts. In the spacing plates 46, as shown in Figs.5 and 7, a cooling water supply port 57 and a return port 59 are formed at the positions corresponding to the lower part of the cylinder body 41. A cooling water outlet 60 to the cylinder head 42 and a cooling water retum port 61 from the cylinder head 42 are formed at the positions corresponding to the upper part of the cylinder body 41. The cooling water supply port 57 is in communication with an cooling water supply passage 62 formed at the bottom part of the cylinder body 41 (Fig.6) and the cooling water return port 59 is in communication with a cooling water return passage 63. In the bottom part of the inner cover 47, a cooling water passage 47a, as shown in Fig.7, is formed for the communication between the cooling water supply port 57 and a cooling water passage 50 which is formed between the outer cover 49 and the inner cover 47, and also a cooling water passage 47b is formed for the communication between a cooling water return port 59 a cooling water return passage 64 which is formed between the outer cover 49 and the inner cover 47. A cooling water passage 46a is formed between the spacing plates 46, 46 and is adapted to communicate with the cooling water supply port 57. The operation of the embodiment having the configuration described above is now explained. The exhaust from respective exhaust port 42a is passed through the inlet 41 d and then collected together in the exhaust collection member 41 b located above the inlet 41 d. The collected exhaust then passes through an outlet 41 e, flows downward within the exhaust passage 48 and then into the exhaust passage 45 via an opening 46b, and exits the bottom of the exhaust passage 45. During this operation, as the catalysts are arranged in parallel to the exhaust gas stream, all amount of the exhaust can flow within the catalysts 53, 54 and thus clarified by those catalysts. Cooling water drawn by a coolant pump (not shown) flows through a cooling water supply passage 62 located at the bottom part of the cylinder body 41, a cooling water supply port 57 of the spacing plates 46, cooling water passages 47a and 50, a cooling water outlet 60, and the cylinder head 42 side, in this order. The cooling water which has cooled the cylinder head 42 then flows through a cooling water return port 61, a cooling water passages 64 and 47b, a cooling water return port 59, in this order, and flows down through a cooling water return passage 63. The cooling water branches at the cooling water supply port 57 and flows from the bottom part to the upper part of the spacing plates 46 through the cooling water passage 46a formed therein. Thus the exhaust and catalysts can be cooled on the both sides of the exhaust passage 48 and the cooling performance is therefore improved. Figs.8 and 9 show another embodiment of the invention: Fig.8 is a plan view of the engine in Fig. 1, and Fig.9 is a partially cross sectional view of the exhaust system shown in Fig.8. For the same structure as in the previous embodiment, same reference numerals are used and the description are omitted. In this embodiment, each exhaust port 42a is opened into the side surface of the cylinder head 42. The exhaust collection member 65 which has a section longitudinal up and down direction and collects exhaust from all exhaust ports 42a is mounted at one end on the upper side surface of the cylinder head 42. The other end of the exhaust collection member 65 is bent toward the cylinder body 41 and connected with one end of an exhaust pipe 66 arranged horizontally along the side surface of the cylinder body 41. The exhaust pipe 66 is extended, within the cowling 14, toward the front F, and bent downward to connect with one end of an exhaust pipes 67 arranged in up and down direction. At the other end of the exhaust pipe 67 is connected an exhaust pipe 68 which extends obliquely downward to the bottom of the cylinder body 41. A water jacket 69 is formed in the outer circumferences of the exhaust collection member 65 and the exhaust pipes 66, 67 and 68. The first catalytic device 53 is disposed in the horizontally extending exhaust pipe 66, while the second catalytic device 54 in the exhaust pipe 67 extending vertically. Cooling water from the cylinder head 42 is supplied to each water jacket 69, and additionally, the water jackets 69 of the exhaust pipes 66 and 67 are supplied with cooling water from a cooling water supply conduit 70. After cooling the exhaust pipes, cooling water flows into the cooling water return passage below the engine. The catalyst charged in the first and second catalytic devices may be the same one, and also may be different ones depending on compositions intended to be clarified, for example, catalytic converter rhodium as first catalyst and NO x reduction catalyst as second catalyst. In this embodiment, though the exhaust pipe 67 is extended toward the front F, it is allowed to be extended toward the rear F. Although the embodiments of the invention have been described, the scope of the invention shall not be limited to it and can be changed or modified variously. For example, the invention may be also applied to 4-stroke cycle engines other than 2-stroke cycle engines referred in the embodiments heretofore. It is apparent from the description above that: according to the invention, a space is efficiently utilized, the volume for catalysts is allowed to be larger, and the catalytic device can be made compact, as the catalysts are arranged in parallel to the exhaust gas stream; further, according to the invention, any size of the catalytic device can be optionally employed by changing the spacing plate in size, without any change of the cylinder body in size; moreover, according to the invention, cooling performance of the catalytic device is improved; in addition, according to the invention, the catalytic devices are successfully contained within the dead space in the cowling, and the arrangement and size of the catalyst can be adopted freely to conform with the contour and size of the space; and according to the invention, the invention is applied effectively to the 4-stroke cycle engine.

Claims: An outboard motor (1) with a catalytic system for an engine (11) having a crankshaft (21) disposed vertically and an exhaust passage (48) in communication with an exhaust port (42a) formed in a side wall of an engine body (20), characterized in that said catalytic system comprises at least one catalyst (53,54) disposed in a same level with regard to said exhaust port (42a) and parallel to an exhaust gas stream. An outboard motor (1) according to claim 1, characterized by a cylinder body (41) and a cylinder head (42) defining said engine body (20); an exhaust outlet (41 e) formed on an upper side wall of said cylinder body (41); a first exhaust passage (45) formed in a lower part of said cylinder body (41); at least one spacing plate (46) secured so as to cover said exhaust outlet (41e) and said first exhaust passage (45); at least one cover (47,49) attached to said spacing plate (46); and a second exhaust passage (48) formed between said spacing plate (46) and said cover (47,49). An outboard motor (1) according to claim 1 or 2, characterized in that two catalysts (53,54) are arranged in parallel relationship to each other. An outboard motor (1) according to claim 2 or 3, characterized in that at least one cooling water passage (47a,47b,50) is formed in said spacing plate (46) and cover (47.49). An outboard motor (1) according to claim 1, characterized by a cylinder body (41) and a cylinder head (42) defining said engine body (20); an exhaust collection member (65) secured on an upper side surface of said cylinder head (42) so as to collect exhaust gas from an exhaust port (42a); an exhaust pipe (66) connected with said exhaust collection member (65) and disposed horizontally, along a surface of said cylinder body (41); and another pipe (67) connected with said exhaust pipe (66) and disposed vertically along said surface of said cylinder body (41), wherein said at least one catalyst (53,54) is disposed in said horizontally extending exhaust pipe (66) or vertically extending exhaust pipe (67), respectively. An outboard motor (1) according to claim 5, characterized in that a first catalytic device (53) is disposed in said horizontally extending exhaust pipe (66), whereas a second catalytic device (54) is disposed in said exhaust pipe (67) extending vertically. An outboard motor (1) according to claim 5 or 6, characterized in that a cooling water passage (69) is formed on an outer circumference of said exhaust collecting member (65) and said exhaust pipes (66,67). An outboard motor (1) according to at least one of the preceding claims 2 to 4, characterized in that two spacing plates (46) are disposed extending from said cylinder body (41) toward said cylinder head (42) and being formed with openings (46a,46b) for communication with said exhaust outlet (41e) and said exhaust passage (45). An outboard motor (1) according to at least one of the preceding claims 1 to 8, characterized in that a cooling water supply port (57) and a return port (59) are formed at the positions corresponding to a lower part of said cylinder body (41). An outboard motor (1) according to at least one of the preceding claims 1 to 9, characterized in that said engine is a 4-stroke cycle engine.

Inventors: ISHII YASUSHI, ISHII, YASUSHI, Ishii, Yasushi, c/o Sanshin Kogyo Kabushiki Kaisha
Applicants: YAMAHA MARINE KK, YAMAHA MARINE KABUSHIKI KAISHA
Application year: 2000
Main classification: F02B61
IPC codes: F01P3, F01N7, F02B75, F01N3, F02F1, F02B61, B63H20