JP2012246881A - Exhaust device of outboard motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust device of an outboard motor having a substantially compact structure and capable of achieving superior exhaust performance, and thus, superior engine performance.SOLUTION: A water jacket 50 is attached to an exhaust manifold 26 connected with an exhaust port to annularly cover an outer side of an exhaust passage inside the exhaust manifold 26. A coolant for engine cooling is circulated as a refrigerant of the water jacket 50 of the exhaust manifold 26. A siphon-shaped exhaust pipe 27 is connected with the exhaust manifold 26. A water jacket 58 is attached to annularly cover an outer side of a siphon-shaped anterior part. Seawater is supplied directly into the water jacket 58 and is circulated therein.

Description

  The present invention relates to an exhaust device for discharging combustion gas from an engine mounted on an outboard motor.

  Major outboard propulsion engines or propulsion systems include outboard motors, inboard motors, and inboard motors. Outboard motors are called outboard drives, etc., and are composed of an engine, its catchers, drive system gears, shafts, screws, etc., and are generally mounted on a transom board at the stern of the hull. . Typically, it is mounted on a small boat or the like and has a steering function and a tilting function.

  Inboard / outboard motors are called inboard engines / outboard drives, etc., as a method of installing propulsion engines for small vessels, etc., and the engine is mounted on the stern part of the ship and the reduction gear, forward / reverse clutch, propeller, etc. are integrated. This is a drive unit arranged outside the transom board.

  In any of these outboard motors, outboard motors or inboard motors, when an engine that is an internal combustion engine is mounted as a power source, an intake device that supplies combustion air to the engine or an exhaust device that exhausts exhaust gas after combustion is used. It is an extremely important device because it significantly affects engine performance. In outboard motors and the like, restrictions are more severe than in the case of land, particularly in relation to the usage environment. Particularly in the exhaust system, it is extremely important whether it can be effectively used under such conditions, and various devices have been made conventionally.

  Specifically, exhaust systems and the like in this type of outboard motor are known, including those described in the following patent documents. As disclosed in these patent documents, each has its own features and problems.

JP 2008-169707 A Japanese Patent No. 2984027 US Pat. No. 7,390,232 JP 2001-173443 A Japanese Patent Application Laid-Open No. 7-144697

In the outboard motor with a catalyst described in Patent Document 1, since the catalyst is located at a position near the exhaust outlet end (propeller), there is a problem that it is likely to be flooded by the surrounding seawater that has flowed back through the exhaust passage during reverse travel. Further, in order to store the catalyst in the cover, it is necessary to bend the exhaust passage rapidly, and there is a problem that the exhaust pressure loss is large and the engine output performance cannot be improved.
Moreover, in the thing of patent document 2, since a catalyst is located downstream from the vertex of an exhaust pipe (riser), the exhaust temperature in a catalyst position falls and purification efficiency deteriorates. In addition, since the catalyst is located in a substantially horizontal position, water in which the water vapor in the exhaust is condensed (liquefied) is difficult to be discharged, and since it is close to the exhaust outlet end, the surrounding seawater that has flowed back from the exhaust outlet end during reverse travel, etc. There is a problem that it is easily exposed to water.

  Moreover, in the thing of patent document 3, since a catalyst is far from an exhaust open end and is located in an exhaust gas ascending region or an ascending section, there is no problem of backflow water / condensed water. However, since the exhaust pipe is collected at a position far from the engine exhaust port (outside the entire length of the engine) and then connected to the pipe provided with the catalyst, the catalyst temperature cannot be raised, and the purification efficiency cannot be increased. .

Further, in an inboard / outboard motor having a dry exhaust system described in Patent Document 4, a pipe is provided around the exhaust system parts so that the surface temperature of the exhaust system parts is sufficiently lowered to prevent thermal damage to the hull and other parts. It must be provided and cooled with air. For this reason, there is a problem that the hull (engine room) space increases and the effective use volume of the hull decreases.
Patent Document 5 discloses an example of dry exhaust in PWC (Personal Water Craft). In this case, since the muffler has a double-pipe structure and seawater is inserted between the muffler and cooled, the space around the muffler is smaller than that of the air-cooled dry exhaust method, but there is a problem that the weight is increased.

In another example, the engine is indirectly cooled (circulated), and the exhaust manifold and the exhaust pipe are dry cooled with seawater or a circulating liquid. Since the exhaust temperature immediately after being discharged from the engine is high, it becomes difficult to seal the joint surface, and in this example, the gas passage and the cooling water passage are separated, but this structure has the problem of further increasing the weight. is there.
In another example, the exhaust manifold and the exhaust pipe are indirect circulation cooling, and the passage is enlarged to ensure the sealing performance of the joint, but the catalyst is located away from the engine exhaust port, and the purification efficiency is increased. There is a problem.

  Further, in Patent Document 3 described above, indirect cooling with circulating coolant is performed up to the position of the catalyst in the exhaust gas upstream region, and the subsequent exhaust is indirect cooling with seawater. However, not only the engine, but also the exhaust manifold and exhaust pipe parts are indirectly cooled with the circulating fluid, and the catalyst is located away from the engine exhaust port, so a large part is circulated and cooled, resulting in a large heat exchange. A vessel is required.

  In view of such circumstances, an object of the present invention is to provide an outboard motor exhaust system that achieves excellent exhaust performance, and hence engine performance, in a substantially compact configuration.

  An exhaust system for an outboard motor according to the present invention includes an engine housed in an engine case and an outboard motor equipped with a propulsion device driven by the engine outside the engine case. An exhaust apparatus for discharging, characterized in that a water jacket is attached to an exhaust manifold connected to an exhaust port so as to cover the outside of an exhaust passage in the exhaust manifold in an annular shape.

In the outboard motor exhaust system of the present invention, the water jacket of the exhaust manifold is provided with an inlet for injecting refrigerant from the lower end portion of the exhaust manifold and an exhaust port for discharging the refrigerant from the upper end portion thereof. It is characterized by that.
In the exhaust system for an outboard motor according to the present invention, an engine cooling coolant is circulated as a coolant for the water jacket of the exhaust manifold.
In the exhaust system for an outboard motor according to the present invention, the exhaust manifold has an exhaust opening end opened upward.

  Further, in the outboard motor exhaust system of the present invention, a siphon-like exhaust pipe is connected to the exhaust manifold, and a water jacket is attached so as to cover the outside of the front half of the siphon in an annular shape. It is characterized by supplying seawater directly and distributing it.

In the exhaust system for an outboard motor according to the present invention, seawater is discharged into an exhaust passage in a siphon-like second half portion of the exhaust pipe.
In the outboard motor exhaust device of the present invention, seawater is once led out from the top of the water jacket corresponding to the siphon-shaped top of the exhaust pipe to the outside through the pipe, and the seawater is It is introduced into an injection nozzle mounted in the exhaust passage of the exhaust pipe.
In the exhaust apparatus for an outboard motor according to the present invention, the injection nozzle is mounted immediately after the siphon-shaped top portion and is directed downstream of the exhaust pipe exhaust passage.

In the exhaust system for an outboard motor according to the present invention, an oxygen sensor or an air-fuel ratio sensor is disposed in a siphon-like front half of the exhaust pipe.
In the exhaust apparatus for an outboard motor according to the present invention, a sacrificial metal is disposed in a water jacket of the exhaust pipe.
In the exhaust apparatus for an outboard motor according to the present invention, a catalyst is installed between the oxygen sensor or air-fuel ratio sensor and the injection nozzle.

According to the present invention, by attaching a water jacket to the exhaust manifold, it is possible to effectively cool the exhaust manifold so that the engine room is not overheated by exhaust heat, and the exhaust manifold and the like are made of an inexpensive material. Can do. In this case, since the water jacket of the exhaust manifold is not directly connected to the engine side, an automobile engine or the like can be used as it is at low cost, which is extremely advantageous in terms of cost.
In addition, a cooling system can be configured at low cost by circulating coolant for cooling the engine as a coolant for the water jacket of the exhaust manifold.

  In addition, a siphon-like exhaust pipe is connected to the exhaust open end opened upward of the exhaust manifold, and a water jacket is attached so as to cover the outside of the front half of the siphon in an annular shape, and seawater is directly supplied and distributed. Let Thus, the exhaust pipe can be effectively cooled without causing the moisture contained in the exhaust gas to flow backward to the engine side.

It is a perspective view which shows the example of the ship or boat which mounts the outboard motor which concerns on this invention. It is a perspective view which shows the external appearance of the outboard motor of this invention. It is a rear view which shows the external appearance of the outboard motor of this invention. It is a side view which shows the external appearance of the outboard motor of this invention. It is a front view which shows the external appearance of the outboard motor of this invention. It is a perspective view which shows the structural example inside the engine case in the outboard motor of this invention. It is a disassembled perspective view of the main components inside the engine case in the outboard motor of the present invention. It is a perspective view which shows the structure and arrangement example of the engine unit of the outboard motor of this invention. It is a perspective view which shows the structural example of the exhaust apparatus in the intake / exhaust system of the outboard motor of this invention. FIG. 4 is a side view showing an arrangement configuration example of the exhaust system of the outboard motor of the present invention with the engine side and a side cross-sectional view showing an arrangement configuration example of the intake and exhaust systems around the cylinder head. It is the top view and front view which show the example of arrangement structure with the engine side of the exhaust apparatus of the outboard motor of this invention. FIG. 4 is a perspective view and a cross-sectional view showing the periphery of an exhaust manifold or an exhaust pipe in the exhaust device for an outboard motor according to the present invention. FIG. 3 is a longitudinal sectional view, a transverse sectional view, and a top view of an exhaust manifold according to the exhaust device for an outboard motor of the present invention. It is a block diagram which shows schematically the cooling system containing circulation paths, such as cooling water, in the exhaust device of the outboard motor of this invention.

Hereinafter, preferred embodiments of an exhaust device for an outboard motor according to the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a ship or a boat equipped with an outboard motor 10 according to the present invention. In this example, the ship is typically small and medium, and has a transom board 2 (stern board) at the rear of the hull 1. The outboard motor 10 is mounted using the transom board 2 as shown. Note that, in the main points of the respective drawings referred to below, the front (the bow side) is indicated by an arrow Fr, and the rear (stern side) is indicated by an arrow Rr. Moreover, the left-right direction (ship width direction) of a hull is shown with the arrow L and the arrow R as needed.

  First, in the hull 1 according to the present embodiment, a ship floor 3 is laid at the bottom of the hull 1 as shown in FIG. 1, and a transom board 2 is disposed at the rear end of the ship floor 3. A cockpit 4 is provided in the vicinity of the center of the ship floor 3, and devices, instruments, instruments, and the like necessary for steering including the handle 5 are disposed in the cockpit 4. The outboard motor 10 is integrally equipped with power, a propulsion device, a steering device, a tilt device, and the like, and is configured as a so-called all-in-one type. The outboard motor 10 can be operated if there are normal equipment such as a fuel tank and a battery on the hull 1 side. is there.

  In addition, the ship is not limited to the illustrated example, and there is also a hull having a bracket for mounting an outboard motor on the rear side of the transom board, that is, a stern plate or a part corresponding to the stern plate on the stern of the hull. The outboard motor 10 of the present invention can be effectively applied to a type having members.

  2 to 5 show the exterior of the outboard motor 10, FIG. 2 is a perspective view of the outboard motor 10, FIG. 3 is a rear view, FIG. 4 is a side view, and FIG. The outboard motor 10 has a resin engine case 100. The engine unit 100 houses an engine unit as a power source, which will be described later, and a screw (propeller) is disposed below the rear of the engine case 100. To rotate the screw. The engine case 100 also functions as an exterior member that constitutes the exterior of the outboard motor 10 and exhibits an exterior with a sense of unity as a whole.

  Referring also to FIG. 1, engine case 100 is configured as a housing having substantially the same width as the stern portion (typically, transom board 2) of hull 1. In this example, the basic form of the engine case 100 is a substantially rectangular parallelepiped, and the longitudinal direction of the rectangular parallelepiped is the ship width direction. The engine case 100 includes a case main body 101 that houses the engine unit and its peripheral components or members, and a case cover 102 that covers an upper opening of the case main body 101.

  The engine unit housed in the engine case 100 and its peripheral parts will be described. The outboard motor 10 of the present invention uses an internal combustion engine as a main power as its power unit, and drives this to drive the propulsion unit. FIG. 6 shows a configuration example inside the engine case 100 in the outboard motor 10, and FIG. 7 is an exploded perspective view of a main configuration inside the engine case 100. In the engine case 100, the engine unit 11 constituting the power unit is arranged and accommodated in a compact and well-balanced manner. In this embodiment, two engine units 11 are provided, and a pair of engine units 11 are arranged in a center distribution on the left and right sides of an engine case 100 in which the longitudinal direction of the casing is the ship width direction. Each engine unit 11 is connected to an intake system 12 and an exhaust system 13, and a power transmission mechanism 14 is coupled to each output end (crankshaft). The power transmission mechanism 14 is coupled to the propulsion unit 15 at the center in the left-right direction on the rear side of the engine unit 11, and these outboard motor components are mounted and supported on the frame 16 as shown in FIG.

  More specifically, the engine unit 11 uses a water-cooled in-line four-cylinder four-cycle gasoline engine in this example. The number of engine cylinders and the like can be appropriately changed as necessary, and is not limited to this example. Referring to FIG. 8, in engine unit 11, crankcase 17, cylinder block 18, cylinder head 19 and cylinder head cover 20 are integrally coupled so as to sequentially overlap, and an oil pan 21 is attached to the lowermost part. The crankshaft of each engine unit 11 is disposed along the ship width direction (left-right direction), and the engine output shaft coupled to the shaft end is disposed on both the left and right sides, that is, the engine of the right engine unit 11. The output shaft is arranged on the right side, and the engine output shaft of the left engine unit 11 is on the left side.

  Next, in the intake system 12, a single air cleaner 22 is disposed between the engine units 11 as shown in FIG. On the other hand, as shown in FIG. 8, intake manifolds 23 are coupled to the front side of the cylinder head 19 of the right engine unit 11 and to the rear side of the cylinder head 19 of the left engine unit 11, respectively. The air cleaner 22 is connected to each other via an intake pipe 24. An intake pipe 25 extends from the front surface of the air cleaner 22 to the hull 1 side in front of the engine case 100 (see FIG. 9), and takes in air from an air intake port at the tip thereof. The air intake is installed in a room or space that is not exposed to waves, splashes, rain, or the like in the hull 1. As shown in FIG. 8, in each engine unit 11, a single intake pipe 25 branches into a plurality (four in this example) in the intake manifold 23.

  In the exhaust system 13, as shown in FIG. 7 and the like, exhaust manifolds 26 are coupled to the rear side of the cylinder head 19 of the right engine unit 11 and to the front side of the cylinder head 19 of the left engine unit 11, respectively. Connected to a single exhaust pipe 27. A rubber exhaust hose 28 is connected to the exhaust pipe 27, and a muffler 29 is connected to the exhaust hose 28. An exhaust hose 30 is connected to the muffler 29, and exhaust gas is discharged from an exhaust outlet 31 attached to the exhaust hose 30.

  The muffler 29 is installed outside the lower surface of the case body 101 of the engine case 100. In this case, the muffler 29, the exhaust hose 30 and the like are arranged so as not to substantially protrude from the lower surface of the case body 101, and the left and right sides of the rear side of the case body 101 are well balanced from the exhaust outlets 31 arranged near the lower portions. Exhausted into water.

  The power transmission mechanism 14 transmits the output of the engine unit 11 to the propulsion device 15. In the power transmission mechanism 14, a speed reducer 32 is connected to the engine output shafts of the left and right engine units 11 as shown in FIG. 7. A gear group is rotatably supported in a casing 33 of the speed reducer 32, and a tie rod 34 is connected to the output shaft. The left and right tie rods 34 are arranged concentrically and horizontally in the left-right direction, and are connected to the intermediate speed reducer 35 at the center in the left-right direction. Each tie rod 34 is connected to the reduction gear 32 and the intermediate reduction gear 35 via universal joints 36 and 37 at both ends. In addition, the tie rod 34 has a spray line engagement structure at an appropriate position in the axial direction, and the entire length can be expanded and contracted.

  The intermediate reduction gear 35 includes a pair of input side bevel gears connected to the tie rods 34 and an output side bevel gear meshing with these input side bevel gears. The output side bevel gear is connected to the drive shaft in the drive shaft case 38, and the intermediate speed reducer 35, the drive shaft case 38, and the swivel bracket 39 are integrally coupled to each other. The drive shaft extends downward from the intermediate speed reducer 35. These swivel brackets 39 and the like are rotatably supported by the case body 101 via bearings 40.

  The propulsion device 15 is arranged below the drive shaft case 38 as shown in FIG. The propulsion device 15 includes a gear case 41 containing a gear for driving a propeller, and has a fin shape as a whole. A propeller 42 is mounted on the rear end portion of the gear case 41. The drive shaft extends further downward through the drive shaft case 38 and extends into the gear case 41. A final reduction gear is configured in the gear case 41, and the propeller 42 can be rotationally driven through the final reduction gear.

  Further, a tilt mechanism and a steering mechanism for the propulsion device 15 are provided. Although a detailed description thereof will be omitted, first, the intermediate speed reducer 35, the drive shaft case 38, and the propulsion unit 15 as a whole can be vertically rotated around the tilt axis T (see FIGS. 2 and 3) by the tilt mechanism. It is. The tilt axis T is set coaxially with the tie rod 34, and the propulsion device 15 can tilt around the tilt axis T. The tilt mechanism may be provided with a drive device called a so-called power trim tilt (PTT) or the like, and an electrohydraulic tilt mechanism may be configured.

  Further, the propulsion unit 15 can be rotated in the yaw direction (left-right direction) around the steering shaft S (see FIGS. 2 and 3) by the steering mechanism (yawing). In this steering mechanism, for example, it has a steering cylinder that is hydraulically driven in an electro-hydraulic manner, and the propulsion unit 15 rotates in the left-right direction, that is, performs a steering operation by reciprocating along a steering rod using a hydraulic pump as a hydraulic source. be able to.

  The main components of the outboard motor 10 described above are mounted and supported on the frame 16 as shown in FIG. The frame 16 is formed using a material such as a steel pipe so as to have an outer shape substantially along a rectangular parallelepiped of a casing constituting the engine case 100 as shown in FIG. A plurality of engine mounts 43 for mounting and supporting the engine unit 11 are disposed at predetermined portions of the frame 16, and the engine unit 11 is mounted on the frame 16 through the engine mounts 43. A main bracket 44 to which a bearing 40 for supporting the swivel bracket 39 and the like described above is attached is attached to the rear portion of the frame 16.

  Further, a plurality of transom bolts 45 are attached to the front portion of the frame 16 facing the front. Outboard motor components such as the engine unit 11 are mounted on the frame 16, and the frame 16 mounting them is housed in the engine case 100. The transom bolt 45 passes through the front surface portion of the case body 101 of the engine case 100 and is fastened to the transom board 2, whereby the entire engine case 100 can be fastened and fixed to the transom board 2. The transom bolt 45 protruding from the case main body 101 is fitted with a seal or packing to ensure water tightness.

  As described above, the engine case 100 includes the case main body 101 that houses the engine unit 11 and its peripheral components, and the case cover 102 that covers the upper opening of the case main body 101. When the case cover 102 is closed with respect to the case main body 101, the inside of the engine case 100 becomes a substantially sealed space, and high water tightness is ensured. In this case, the constituent members of the outboard motor 10 are supported by the frame 16, and the frame 16 holds the engine unit 11 and is responsible for the propulsive force and steering force of the propulsion unit 15, that is, the load on the engine case 100 itself. Does not take. Further, as shown in FIG. 1, the engine case 100 also functions as an exterior member of the outboard motor 10, and is mounted on the outboard motor 10 so as to exhibit a unity appearance as a whole.

  As shown in FIGS. 2 to 4 and the like, on the rear surface side of the case main body 101, in the region from the rear surface portion to the bottom surface portion, it is formed to be recessed inward of the case main body 101 at the center in the ship width direction. A recess 103 is provided. Around this recess 103, a propulsion unit 15 constituting the propulsion device, its tilt and steering mechanism, and the like are disposed. The recess 103 is formed from the rear side of the case main body 101 toward the front, and is necessary so that the tilt mechanism and the steering mechanism or peripheral devices and members thereof do not interfere with the case main body 101 when the tilt or steering operation is performed. A sufficient gap is provided.

  Further, as described above, equipment such as a fuel tank and a battery is provided on the hull 1 side, and these equipment and the outboard motor 10 are connected or coupled. In this case, as shown in FIG. 5, a plurality of through-holes 104 are formed in the form of making a hole between the front portion of the casing 101 and the transom board 2. That is, a through hole 104A for inserting the intake pipe 25 for supplying combustion air to the engine, a through hole 104B for inserting a fuel pipe for supplying fuel from the fuel tank to the engine, and the inside of the engine case 100 A through-hole 104C for passing a cylinder for ventilation air for ventilating the air is formed. Further, a cord or cable for electrically (including a control signal) or mechanical connection between a device or equipment or member in the engine case 100 and the control device on the hull 1 side is inserted. A hole 104D is formed. These through holes 104 are provided with watertight holding means (seal or the like) when the intake pipe 25 or the like is mounted.

  The case cover 102 constitutes an upper surface portion of the engine case 100, and is coupled to be rotatable via a hinge 105 in the vicinity of the rear upper end of the case main body 101 as shown in FIG. 2 or FIG. By opening the case cover 102 around the hinge 105, the inside of the engine case 100 is opened, and the exposed engine unit 11 and the like inside the engine case 100 can be freely accessed. The case cover 102 can be opened to easily check the inside, and the convenience of this type of work can be improved.

  Note that a seal is laid on the closing portion or mating surface of the case main body 101 and the case cover 102, and the case cover 102 is closed with respect to the case main body 101, so that high water tightness of the engine case 100 is secured and maintained. In this case, the seal is laid all around the mating surface of the case main body 101 and the case cover 102. When the case cover 102 is closed, the case cover 102 is sandwiched between the case body 102 and the closed portion of the case main body 101, thereby obtaining high water tightness with respect to the engine case 100.

Moreover, when the case cover 102 is closed with respect to the case main body 101, it has the lock mechanism 106 as shown in FIGS. 2-4 for fixing and holding the case cover 102 in the closed state.
On the other hand, it has a holding mechanism that can hold the case cover 102 in its open state, and a detailed description of this holding mechanism is omitted, but the case cover 102 can be held in the open state with respect to the case body 101. .

  In the above case, in addition to the constituent members of the outboard motor 10 described above, an electric signal or electric power is transmitted / received between the cooling piping system of the engine unit 11, the hydraulic piping system for driving the tilt mechanism and the steering mechanism, or between the members. An electric signal line or a cord for performing the operation is routed to an appropriate position in the engine case 100, and auxiliary machinery necessary for operating the outboard motor 10 is provided. An appropriate operation of the outboard motor 10 is performed through these piping systems or the like, or by operating auxiliary machinery.

  In the present invention, as shown in FIG. 9, the exhaust system 200 includes an exhaust manifold 26, an exhaust pipe 27, an exhaust hose 28, a muffler 29, an exhaust hose 30, and the like in the exhaust system 13. The exhaust device 200 discharges combustion gas generated in the engine. As shown in FIG. 10B, the intake manifold 23 and the exhaust manifold 26 are coupled to both sides of the cylinder head 19 with the cylinder head 19 interposed therebetween. The intake manifold 23 is connected to an intake port 46 of each cylinder, and an air-fuel mixture is supplied to the intake port 46. The air-fuel mixture sucked into the combustion chamber 47 from the intake port 46 is discharged to the exhaust port 48 after explosion. The exhaust port 48 of each cylinder is connected to the exhaust manifold 26, and the exhaust gas from each cylinder joins in the exhaust manifold 26 and is discharged into the water from the exhaust outlet 31 through the exhaust pipe 27 and the muffler 29.

  As shown in FIG. 11, the exhaust manifold 26 is extended on the side of the exhaust port 48 of the engine unit 11 in the cylinder arrangement direction, that is, in the ship width direction. The exhaust pipe 27 extends substantially upwardly from the exhaust manifold 26, and is folded back while being bent in a substantially U shape, to which an exhaust hose 28 is connected. The exhaust pipe 27 curved in this way is arranged in a siphon shape. The exhaust hose 28 extends downward in a substantially straight line and is connected to a muffler 29 disposed at the bottom of the engine case 100 while being appropriately curved.

  FIG. 12 shows the exhaust manifold 26, the exhaust pipe 27, and the exhaust hose 28 that are connected to each other. In this example, since the engine unit 11 is an in-line four-cylinder engine, it has four manifolds 26A to 26D as shown in FIG. 12 (a), and each of the manifolds 26A, 267B, 26C, and 26D has a corresponding cylinder. Connected to the exhaust port 48. In this example, the manifolds 26A to 26D join together in the vicinity of the # 2 or # 3 cylinders, and communicate with an opening 49 opened upward as an exhaust opening end.

  A water jacket 50 is attached and formed so as to cover the exhaust passage formed inside the exhaust manifold 26, that is, the outside of the manifolds 26A to 26D. The water jacket 50 is formed not only outside the exhaust passage, but also between the manifolds 26A to 26D, that is, between the manifolds 26A and 26B, between the manifolds 26B and 26C, and between the manifolds 26C and 26D. To do. In the engine unit 11, the engine used for this is a water cooling type, and a water cooling water jacket is formed in the cylinder block 18 and the cylinder head 19, and an ordinary circulating coolant (LLC; long life coolant, etc.) is used as the cooling medium. And a cooling water pump (not shown) for circulating the same. This cooling water pump uses the driving force of the engine of the engine unit 11 as its driving source.

  Further, in the present embodiment, the coolant for the engine cooling described above is used as the coolant flowing through the water jacket 50 of the exhaust manifold 26, and the cooling water pump of the engine unit 11 described above is used for the circulation. As shown in FIG. 13, the water jacket 50 of the exhaust manifold 26 is provided with an inlet 51 for injecting refrigerant, that is, coolant from the lower end portion of the exhaust manifold 26, and an exhaust port for discharging the coolant from the upper end portion. The coolant injected from the injection port 51 is circulated in the water jacket 50 and discharged from the discharge port 52. The inlet 51 and the outlet 52 are each connected to a water jacket formed in the engine of the engine unit 11 via a connection hose. In this case, since the water jackets of the engine and the exhaust manifold 26 are not adjacent to each other, no coolant leaks between the exhaust manifold 26 and the cylinder head 19 in a high temperature environment.

  Further, a gasket 53 as shown in FIG. 12 is interposed at the connecting portion between the cylinder head 19 and the exhaust manifold 26, and the gasket 53 is sandwiched between the cylinder head 19 and the exhaust manifold 26 from both sides. The gasket 53 has four openings 53a corresponding to the openings of the manifolds 26A to 26D. In this case, the portions other than the manifolds 26A to 26D, that is, the portions corresponding to the water jacket 50 are substantially closed, and the exhaust gas is circulated at the connection portion between the cylinder head 19 and the exhaust manifold 26, but the cooling water is blocked. It is like that.

  FIG. 14 is a block diagram schematically showing a cooling system including a circulation path such as cooling water. The water jacket of the cylinder block 18 and the cylinder head 19 in the engine unit 11 and the water jacket 50 of the exhaust manifold 26 communicate with each other via the inlet 51 and the outlet 52 as described above. In this cooling system, the cooling water is constantly circulated in the engine and the exhaust manifold 26 by the cooling water pump 54 driven by the engine. Further, a heat exchanger 55 for cooling the cooling water is mounted, and the cooling water is cooled by the heat exchanger 55. In the heat exchanger 55, for example, cooling water from a water jacket of the engine is drawn into the heat exchanger 55, and seawater or fresh water around the outboard motor 10 is pumped up by a pumping pump 56 and supplied to the heat exchanger 55. The And while the seawater etc. distribute | circulate in the heat exchanger 55, it takes the heat of the high-temperature cooling water, and this cools the cooling water. In addition, a thermostat 57 is inserted in an appropriate position in the cooling system circulation path, and when the engine is warmed and the cooling water reaches a predetermined temperature or more, the valve of the thermostat 57 is opened and the cooling water flows into the heat exchanger 55. Cooling water temperature decreases.

  As described above, the exhaust pipe 27 bends in a siphon shape. As shown in FIG. 12B, the water jacket 58 is attached so as to cover at least the front half of the siphon in an annular shape. It is designed to supply and distribute seawater directly inside. In the illustrated example of FIG. 12B, the water jacket 58 is formed up to the further siphon-shaped second half region. Further, the exhaust pipe 27 is coupled to the exhaust manifold 26 via an intermediate pipe 59, and the periphery of the intermediate pipe 59 is also covered with a water jacket 58. Seawater or water discharged from the heat exchanger 55 is discarded outside the outboard motor 10, but a part of the seawater or water is supplied to the water jacket 58. In this case, the water channel passes through the branch pipe 60 from the fuel exchanger 55, one is connected to the lowermost part of the water jacket 58 via the supply hose 61A, and the other is exhausted from the water jacket 58 via the supply hose 61B. Connected to the rear end of the direction.

  Further, the seawater is discharged into the exhaust passage in the second half of the exhaust pipe 27 in the siphon shape. In this case, as shown in FIG. 12B, the injection nozzle 62 is mounted immediately after the siphon-shaped top of the exhaust pipe 27, and seawater is discharged from the injection nozzle 62 toward the downstream direction of the exhaust passage of the exhaust pipe 27. Is done. A pipe 63 for supplying seawater to the injection nozzle 62 is provided, and one end of the pipe 63 is connected to the siphon-like top of the exhaust pipe 27, that is, the top of the water jacket 58. The other end of the pipe 63 is connected to the injection nozzle 62. In this way, the seawater in the water jacket 58 is once led out from the uppermost part through the pipe 63 to the outside and introduced into the injection nozzle 62 mounted in the exhaust passage of the exhaust pipe 27.

  As described above, the branch pipe 60 is used to feed seawater from the lowermost portion of the water jacket 58, particularly via the feed hose 61A, and lead it out from the outlet provided at the uppermost portion to the injection nozzle 62. Therefore, air lock is not performed in the seawater flow passage in the water jacket 58, and all water is discharged backward from the lowermost portion of the water jacket 58 when the engine is stopped. Further, since the injection nozzle 62 is installed so as to discharge from the siphon-like apex in the downstream direction of the exhaust passage, the catalyst and the oxygen sensor described later are not splashed with water.

  A catalyst 64 is arranged inside the siphon-shaped front half of the exhaust pipe 27, that is, before reaching the siphon-shaped apex. The catalyst 64 is housed and held so as to be wrapped with a tubular holder 65 from the outside. A retaining ring 66 is mounted on the downstream side of the exhaust passage of the holder 65 and is positioned by the retaining ring 66, and has a flange portion 65 a on the upstream side, and is held by being sandwiched between the end surface of the intermediate pipe 59. Is done. Note that a gasket 67 including a region of the water jacket 58 is attached to a joint portion between the exhaust pipe 27 and the intermediate pipe 59.

  Further, an air-fuel ratio (A / F) sensor 68 is disposed upstream of the exhaust passage of the catalyst 64, and an oxygen sensor 69 is disposed downstream thereof. Based on the detection data of these sensors 68 and 69, the A / F is appropriately adjusted in the outboard motor control device according to the operating state. As described above, the exhaust pipe 27 extends upward from the vicinity of the center of the exhaust manifold 26, is bent in a direction orthogonal to the engine longitudinal direction (crankshaft), and is connected to the exhaust hose 28. Accordingly, the exhaust device 200 including the A / F sensor 68, the catalyst 64, the oxygen sensor 69, the first half of the exhaust rising, the injection nozzle 62, and the second half of the exhaust downflow is arranged and configured extremely compactly. As a result, the catalyst 64 can be disposed close to the exhaust port 48 of the engine, so that the temperature of the catalyst 64 does not decrease and the purification efficiency is good. Note that only one of the A / F sensor 68 and the oxygen sensor 69 can be used.

  As described above, seawater is supplied and circulated in the water jacket 58 of the exhaust pipe 27. As a countermeasure against corrosion due to salinity in seawater, a sacrificial metal 70 is attached at an appropriate position in the water jacket 58 as shown in FIG.

  In the basic operation of the outboard motor 10 of the present invention, when the engine unit 11 is started, the power is first input to the speed reducer 32 and then transmitted from the output end to the tie rod 34 via the universal joint 36. The engine power is further transmitted from the tie rod 34 to the intermediate speed reducer 35. In the intermediate speed reducer 35, the engine power is transmitted from the input shaft 57 to the drive shaft 60 via the bevel gear 59 and the bevel gear 61, whereby the drive shaft 60 is rotationally driven. Is done. The driving force of the drive shaft 60 is transmitted to the propeller shaft 64 and further to the propeller 42 via the bevel gear 63 and the bevel gear 65 in the final speed reducer 66 in the gear case 41, whereby the propeller 42 rotates.

  When the engine is operating, particularly in the exhaust system 13, exhaust gas generated in the engine is exhausted from the exhaust device 200. As described above, the exhaust device 200 includes the exhaust manifold 26, the exhaust pipe 27, the exhaust hose 28, the muffler 29, the exhaust hose 30, and the like, and the exhaust gas is finally discharged into the water from the exhaust outlet 31 through the muffler 29. .

Next, the characteristic configuration of the present invention and the operation and effect thereof will be described. First, the exhaust manifold 26 is connected to the exhaust port 48 of the cylinder head 19 of the engine, but the outside of the exhaust passage in the exhaust manifold 26 is annularly formed. A water jacket 50 is attached so as to cover.
By attaching the water jacket 50 to the exhaust manifold 26, which itself has a high temperature, the exhaust manifold 26 can also be effectively cooled so that the engine room is not overheated by exhaust heat. Further, the exhaust manifold 26 can be made of an inexpensive material.

In this case, the water jacket 50 is provided with an inlet 51 for injecting the refrigerant from the lower end of the exhaust manifold 26 and an outlet 52 for discharging the refrigerant from the upper end. That is, the water jacket around the exhaust port 48 of the cylinder head 19 of the engine and the water jacket 50 of the exhaust manifold 26 are not directly connected.
Since the water jacket 50 of the exhaust manifold 26 is not directly connected to the engine side in this way, it does not have a water-cooled exhaust manifold, for example, it does not change the refrigerant flow of an automobile engine, so that the engine can be used as it is inexpensively. it can. Further, the engine cooling system and the like can be designed independently of the cooling system of the exhaust manifold 26, and the cooling system of the exhaust manifold 26 can be set independently of the engine cooling system, thereby expanding the degree of freedom in design. be able to.

Further, an engine cooling coolant is circulated as a coolant for the water jacket 50 of the exhaust manifold 26.
In this way, the cooling system can be configured at low cost by using the same refrigerant as the engine side. In this case, since the engine cooling refrigerant contains a corrosion-resistant additive, the exhaust manifold 26 can be made of an inexpensive material. Further, since the engine cooling refrigerant contains a corrosion-resistant additive, it is not necessary to cover the surface of the water jacket 50 of the exhaust manifold 26 with an expensive surface treatment, so that the cost can be substantially reduced.

Further, the exhaust opening end of the exhaust manifold 26 is opened upward. That is, it has the opening 49 opened upward as an exhaust open end.
In this way, the exhaust manifold 26 is opened upward, so that the exhaust pipe 27 connected to the exhaust manifold 26 can be formed in a siphon shape. By forming the exhaust pipe 26 in a siphon shape, moisture contained in the exhaust gas does not flow back to the exhaust port 48 of the engine. That is, the engine can be effectively protected by preventing the water contained in the exhaust gas from flowing back to the engine side.

Further, a water jacket 58 is attached so as to cover the outside of the siphon-shaped front half of the exhaust pipe 27 in an annular shape, and seawater is directly supplied and circulated in the water jacket 58.
Although the temperature increases due to the exhaust gas flowing through the exhaust pipe 27, the water jacket 58 can be attached to effectively cool the exhaust pipe 27 and prevent the engine room from being overheated by the exhaust heat. Further, the exhaust pipe 27 can be made of an inexpensive material.

In the exhaust pipe 27, seawater is further discharged from the injection nozzle 62 into the exhaust passage in the latter half of the siphon shape.
Water can be injected into the latter half portion (downflow portion) of the exhaust pipe 27 to form a wet exhaust. Thereby, the quantity of the circulating coolant to be used can be reduced, and the heat exchanger can be made smaller. In this case, a large amount of seawater around the outboard motor 10 can be used, which is inexpensive, and surplus cooling water can be discarded. In this way, the exhaust pipe 27 is formed in a siphon shape, the front half thereof is cooled by the water jacket 58, and the latter half is cooled by wet exhaust, whereby the entire exhaust pipe 27 can be cooled extremely efficiently.

  In addition, since the water jacket can be omitted from the wet exhaust formation portion, a lightweight and compact exhaust system can be obtained. In addition, since it is not necessary to use an expensive heat-resistant material for the wet exhaust gas forming portion, an inexpensive material such as rubber can be used. Furthermore, since the temperature of the exhaust itself is lowered, the sound speed can be reduced and the noise can be reduced. In addition, by using a flexible material such as rubber for the wet exhaust formation portion, exhaust permeation noise can be reduced in addition to being not worn or damaged even if the outside is slightly touched.

Further, the seawater is once led out from the uppermost portion of the water jacket 58 of the exhaust pipe 27 to the outside through the pipe 63, and the seawater is introduced into the injection nozzle 62 mounted in the exhaust passage of the exhaust pipe 27.
Thus, the optimal injection | pouring pattern, ie, a spraying state, can be obtained by making the injection nozzle 62 for water injection | pouring into another body. And maintenance work, such as washing of a water nozzle part, can be performed easily. Furthermore, since the air near the top of the water jacket 58 of the exhaust pipe 27 can be released, the water jacket 58 does not air lock.

In this case, the injection nozzle 62 is mounted immediately after the siphon-shaped top, and is directed in the downstream direction of the exhaust passage of the exhaust pipe 27.
By arranging the injection nozzle 62 in this way, the density of the injection nozzle 62 is sufficiently larger than the surrounding exhaust gas until the water evaporates. For this reason, since the injection direction and gravity coincide with each other, the injected water does not flow backward to the oxygen sensor 69, the A / F sensor 68, the catalyst 64, and further the engine main body side upstream of the exhaust. High safety of the exhaust device 200 can be ensured.

In addition, an oxygen sensor 69 or an A / F sensor 68 is disposed in the siphon-shaped front half of the exhaust pipe 27.
Since the state of the exhaust gas can be detected by the oxygen sensor 69 or the A / F sensor 68, the air-fuel ratio of the engine can be feedback-controlled. As a result, the engine can be operated at an optimal air-fuel ratio, fuel efficiency is improved, and exhaust gas components can be controlled. Furthermore, the air / fuel ratio can be adjusted to be suitable for the function of the catalyst 64. In this case, due to the directivity of the injection nozzle 62, the sensor portions of the oxygen sensor 69 and the A / F sensor 68 do not get wet, so that their failure can be prevented.

In this case, a catalyst 64 is installed between the oxygen sensor 69 or A / F sensor 68 and the injection nozzle 62.
As a result, the catalyst 64 does not get wet, the temperature of the catalyst 64 can be kept high, and its proper function can be exhibited. Further, since the temperature around the exhaust passage is not raised while keeping the temperature of the catalyst 64 high, the engine room is not overheated.

A sacrificial metal 70 is disposed in the water jacket 58 of the exhaust pipe 27.
By providing the sacrificial metal 70, the exhaust pipe 27 can be made of an inexpensive material. Further, there is an advantage that it is not necessary to subject the water jacket 58 of the exhaust pipe 27 to an expensive surface treatment.

As mentioned above, although this invention was demonstrated with various embodiment, this invention is not limited only to these embodiment, A change etc. are possible within the scope of the present invention.
In the above-described embodiment, the example in which the exhaust pipe 27 is coupled to the exhaust manifold 26 via the intermediate pipe 59 has been described. However, the exhaust pipe 27 may be coupled directly to the exhaust manifold 26.

DESCRIPTION OF SYMBOLS 1 Hull, 2 Transom board, 3 Ship floor, 10 Outboard motor, 11 Engine unit, 12 Intake system, 13 Exhaust system, 14 Power transmission mechanism, 15 Propulsion machine, 16 Frame, 17 Crankcase, 18 Cylinder block, 19 cylinder Head, 20 Cylinder head cover, 21 Oil pan, 22 Air cleaner, 23 Intake manifold, 24 Intake pipe, 25 Intake pipe, 26 Exhaust manifold, 27 Exhaust pipe, 28 Exhaust hose, 29 Muffler, 30 Exhaust hose, 31 Exhaust outlet, 32 Deceleration Machine, 33 casing, 34 tie rod, 35 intermediate reducer, 36, 37 universal joint, 38 drive shaft case, 39 swivel bracket, 40 bearing, 41 gear case, 42 pro 43, Engine mount, 44 Main bracket, 45 Transom bolt, 46 Inlet port, 47 Combustion chamber, 48 Exhaust port, 49 Opening, 50 Water jacket, 51 Inlet, 52 Outlet, 53 Gasket, 54 Cooling water pump, 55 Heat exchanger, 56 Pumping pump, 57 Thermostat, 58 Water jacket, 59 Intermediate pipe, 60 Branch pipe, 61A, 61B Feeding hose, 62 Injection nozzle, 63 Piping, 64 Catalyst, 65 Holder, 66 Retaining ring, 67 Gasket , 68 A / F sensor, 69 Oxygen sensor, 70 Sacrificial metal, 100 Engine case, 101 Case body, 102 Case cover, 103 Recess, 104 Through hole, 105 Hinge, 106 Lock mechanism, 200 Exhaust device.

Claims (11)

In an outboard motor in which an engine is housed inside the engine case and includes a propulsion device driven by the engine outside the engine case, an exhaust device for discharging combustion gas from the engine,
An exhaust system for an outboard motor, wherein a water jacket is attached to an exhaust manifold connected to an exhaust port so as to cover the outside of an exhaust passage in the exhaust manifold in an annular shape.   2. The outboard as claimed in claim 1, wherein the water jacket of the exhaust manifold is provided with an inlet for injecting refrigerant from a lower end portion of the exhaust manifold and an outlet for discharging the refrigerant from the upper end portion thereof. Machine exhaust system.   The exhaust system for an outboard motor according to claim 2, wherein an engine cooling coolant is circulated as a coolant for a water jacket of the exhaust manifold.   The exhaust device for an outboard motor according to any one of claims 1 to 3, wherein an exhaust opening end of the exhaust manifold is opened upward.   A siphon-like exhaust pipe is connected to the exhaust manifold, a water jacket is attached so as to cover the outside of the front half of the siphon in an annular shape, and seawater is directly supplied and circulated in the water jacket. Item 5. The outboard motor exhaust device according to any one of Items 1 to 4.   6. The outboard motor exhaust system according to claim 5, wherein seawater is discharged into an exhaust passage in a siphon-like second half portion of the exhaust pipe.   From the top of the water jacket corresponding to the siphon-shaped top of the exhaust pipe, the seawater is once led out to the outside through a pipe, and the seawater is introduced into an injection nozzle mounted in an exhaust passage of the exhaust pipe. The outboard motor exhaust system according to claim 6.   The exhaust device for an outboard motor according to claim 7, wherein the injection nozzle is mounted immediately after the top portion of the siphon-like shape and is directed in a downstream direction of an exhaust passage of the exhaust pipe.   The exhaust apparatus for an outboard motor according to any one of claims 5 to 8, wherein an oxygen sensor or an air-fuel ratio sensor is disposed in a siphon-shaped front half of the exhaust pipe.   The exhaust device for an outboard motor according to any one of claims 5 to 9, wherein a sacrificial metal is disposed in a water jacket of the exhaust pipe.   The exhaust apparatus for an outboard motor according to claim 9 or 10, wherein a catalyst is installed between the oxygen sensor or air-fuel ratio sensor and the injection nozzle.

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