Cooling device for marine propulsion engines

Abstract

To sufficiently secure the collecting ability for fine matter even when not using a valve for opening and closing a bypass passage.SOLUTION: A cooling device for an outboard engine has an upstream part 27A of a drain passage, a downstream part 27B of the drain passage, a collection passage 32 provided with a collector 33, and a bypass passage 34 arranged to have a difference between a flowing direction of cooling water flowing into a branch part 35 from the upstream part 27A and a flowing direction of the cooling water flowing into the collection passage 32 from the branch part 35 to be smaller than a difference between the flowing direction of the cooling water flowing into the branch part 35 from the upstream part 27A and the flowing direction of the cooling water flowing into the bypass passage 34 from the branch part 35, and a difference between the flowing direction of the cooling water flowing into a confluent part 36 from the bypass passage 34 and the flowing direction of the cooling water flowing into the downstream part 27B from the confluent part 36 to be smaller than the difference between the flowing direction of the cooling water flowing into the confluent part 36 from the collection passage 32 and the flowing direction of the cooling water flowing into the downstream part 27B from the confluent part 36.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a cooling device for a marine propulsion machine that has a function of collecting fine particles dispersed in water such as seawater or lake water. [Background technology]

[0002] In recent years, pollution of oceans, lakes, rivers, etc. caused by the dispersion of fine debris such as microplastics into seawater, lake water, river water, etc. has become a problem. It is also known that seas, lakes, rivers, etc. are polluted by the dispersion of residues of feed used in aquaculture into seawater, lake water, river water, etc. In order to prevent such pollution, it is desirable to capture and recover fine debris such as microplastics, residues of feed, etc. (hereinafter referred to as "fine objects").

[0003] The following Patent Document 1 describes an outboard motor equipped with a cooling device that has a function of capturing fine particles. The cooling device uses a pump to draw water, such as seawater or lake water, into the outboard motor and supplies the drawn water as cooling water to a water jacket attached to the engine of the outboard motor. The cooling water supplied to the water jacket flows through the water jacket, thereby cooling the engine. After flowing through the water jacket, the cooling water also flows through a drain pipe, passes through a filter device attached midway through the drain pipe, and is then discharged outside the outboard motor. As the cooling water passes through the filter device, fine particles in the cooling water are captured by the filter device and removed from the cooling water. In this way, the cooling device allows seawater, lake water, etc. to be drawn into the outboard motor and fine particles contained in the drawn seawater, lake water, etc. to be captured by the filter device.

[0004] In the cooling device described in Patent Document 1, a bypass passage is connected to a drain pipe in which a filtration device is installed, allowing cooling water to bypass the filtration device when the filtration device becomes clogged. In addition, in this cooling device, a relief valve is provided at the connection between the upstream end of the bypass passage and the drain pipe. When the filtration device is not clogged, the relief valve closes to guide the cooling water flowing through the drain pipe to the filtration device, and when the filtration device becomes clogged, the relief valve opens to guide the cooling water flowing through the drain pipe to the bypass passage, bypassing the filtration device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-163872 Summary of the Invention [Problem to be solved by the invention]

[0006] 8(A) and 8(B) show a configuration equivalent to the drainage side configuration of the conventional cooling device described in Patent Document 1. In FIGS. 8(A) and 8(B), 133 denotes a drainage passage. The drainage passage 133 corresponds to the drainage pipe in the cooling device described in Patent Document 1. Also, 135 denotes a filtration device, 145 denotes a bypass passage, and 144 denotes a relief valve. When the filtration device 135 is not clogged, the relief valve 144 closes as shown in FIG. 8(A). At this time, the cooling water flows through the drainage passage 133, passing through the filtration device 135, as indicated by arrow V in FIG. 8(A). On the other hand, when the filtration device 135 is clogged, the relief valve 144 opens as shown in FIG. 8(B). At this time, the cooling water flows through the bypass passage 145, as indicated by arrow W in FIG. 8(B).

[0007] The inventors of the present application have been considering removing the relief valve 144 from the drainage side configuration of the cooling device, for example, as shown in Figures 8(A) and (B). By removing the relief valve 144, the number of parts can be reduced, lowering the manufacturing cost of the cooling device, and it is also possible to eliminate problems such as breakdowns of the relief valve 144 and the burden of maintaining the relief valve 144. However, removing the relief valve 144 from the drainage side configuration of the cooling device raises the following problems.

[0008] FIG. 9(A) shows the drainage side configuration of the cooling device shown in FIGS. 8(A) and 8(B) without the relief valve 144. When the relief valve 144 is removed from the drainage side configuration of the cooling device, the inlet of the bypass passage 145 is constantly connected to the drainage passage 133. Therefore, as indicated by arrows X1 and X2 in FIG. 9(A), cooling water may flow into the bypass passage 145 even when the filtration device 135 is not clogged. This phenomenon is likely to occur when, as indicated by the two-dot chain line in FIG. 9(A), a linear flow path extending from the drainage passage 133 to the bypass passage 145 is formed at the branch point where the bypass passage 145 branches off from the drainage passage 133. Therefore, the flow direction of the cooling water flowing from the drainage passage 133 into the branch point (arrow X1) and the flow direction of the cooling water flowing from the branch point into the bypass passage 145 (arrow X2) are the same. In this way, even when the filter device 135 is not clogged, if the cooling water flows into the bypass passage 145, the amount of cooling water flowing through the filter device 135 decreases, resulting in a decrease in the cooling device's ability to capture fine objects.

[0009] Furthermore, in the case where the relief valve 144 is removed from the drain side configuration of the cooling system shown in Figures 8(A) and (B), there is a concern that the cooling water that has flowed through the bypass passage 145 will flow out from the outlet of the bypass passage 145 and then flow back through the drain passage 133, causing fine particles accumulated in the filtration device 135 to be stirred up, and that the stirred up fine particles will flow sequentially through the bypass passage 145 and the drain passage 133 together with the cooling water and be discharged outside the outboard motor.

[0010] 9(B), like FIG. 9(A), shows the drain side configuration of the cooling device shown in FIGS. 8(A) and (B) without the relief valve 144. The cooling water that has flowed through the bypass passage 145 normally flows downward through the drain passage 133 after flowing out from the outlet of the bypass passage 145, as indicated by arrows Y1 and Y2 in FIG. 9(B). However, if the amount of cooling water flowing through the bypass passage 145 is large, the flow of the cooling water that has flowed through the bypass passage 145 may become turbulent when it flows out from the outlet of the bypass passage 145, and the cooling water may flow back upward through the drain passage 133, as indicated by arrow Y3 in FIG. 9(B). 9(B), the flow path from the bypass passage 145 to the drain passage 133 is bent at the confluence point where the bypass passage 145 joins the drain passage 133, and therefore the flow direction (arrow Y1) of the cooling water flowing from the bypass passage 145 into the confluence point differs from the flow direction (arrow Y2) of the cooling water flowing downward through the drain passage 133 from the confluence point. When the cooling water flows backward through the drain passage 133, the backflowing cooling water flows from bottom to top within the filtration device 135, and there is a risk that fine objects accumulated in the filtration device 135 will be stirred up by this cooling water. In a configuration in which the relief valve 144 is removed, the inlet of the bypass passage 145 is constantly connected to the drain passage 133, so there is a possibility that the fine particles that are stirred up will enter the bypass passage 145 from its inlet along with the cooling water, flow downward through the bypass passage 145 and the drain passage 133, and be discharged outside the outboard motor. This backflow of cooling water may cause the fine particles that had accumulated in the filtration device 135 to be discharged outside the outboard motor, and therefore this backflow of cooling water will lead to a decrease in the cooling device's ability to collect fine particles.

[0011] Furthermore, in the case where the relief valve 144 has been removed from the drain side configuration of the cooling system shown in Figures 8(A) and (B), if the power source of the outboard motor is an engine, there is a concern that the engine exhaust gas will flow back through the drain passage 133, causing fine particles accumulated in the filtration device 135 to be stirred up, and that the stirred-up fine particles will then flow sequentially through the bypass passage 145 and the drain passage 133 together with the cooling water, and be discharged outside the outboard motor.

[0012] That is, many outboard motors powered by engines have an exhaust chamber provided at the rear of the lower part of the outboard motor, and exhaust gases discharged from the engine are sent to the exhaust chamber through an exhaust passage. When an outboard motor with such a configuration has a water-cooled cooling device, the cooling device is often configured so that cooling water that flows through a drainage passage is discharged into the exhaust chamber. In such a cooling device, the drainage passage and the exhaust passage are connected via the exhaust chamber. Therefore, when the pressure in the drainage passage becomes lower than the pressure in the exhaust chamber, exhaust gas sent from the exhaust passage to the exhaust chamber may flow from the exhaust chamber into the drainage passage and flow back through the drainage passage.

[0013] 9(A) and 9(B), Figure 9(C) shows the drain side configuration of the cooling device shown in Figures 8(A) and 8(B) without the relief valve 144. As indicated by arrow Z in Figure 9(C), exhaust gas flowing back from the exhaust chamber through the drain passage 133 may reach the filter device 135 and flow from bottom to top within the filter device 135. The phenomenon in which exhaust gas flowing back through the drain passage 133 reaches the filter device 135 is likely to occur when, as indicated by the two-dot chain line in Figure 9(C), the flow path in the drain passage 133 from below the filter device 135 to the filter device 135 is linear, and therefore the exhaust gas flowing back through the drain passage 133 flows in a straight line toward the filter device 135. When exhaust gas flows from bottom to top within the filter device 135, fine particles accumulated within the filter device 135 are stirred up by the exhaust gas, and the stirred-up fine particles flow downward together with the cooling water through the bypass passage 145 and the drain passage 133, and may be discharged outside the outboard motor. Therefore, this type of backflow of exhaust gas also leads to a decrease in the cooling device's ability to capture fine particles.

[0014] The present invention has been made in consideration of the problems such as those described above, and an object of the present invention is to provide a cooling device for a marine propulsion unit that can ensure sufficient fine object collection capacity even without using a valve or the like that opens and closes a bypass passage depending on whether or not the collector (filtering device) is clogged. [Means for solving the problem]

[0015] In order to solve the above problems, the present invention Cooling device for a first marine propulsion unita cooling device for a marine propulsion unit that is provided in a marine propulsion unit, takes in water from outside the marine propulsion unit into the marine propulsion unit, flows the taken-in water around or inside a power source of the marine propulsion unit as cooling water to cool the power source, and discharges the cooling water after flowing around or inside the power source to the outside of the marine propulsion unit, the cooling device comprising: a drainage passage for discharging the cooling water after flowing around or inside the power source to the outside of the marine propulsion unit; a collection passage interposed between an upstream portion and a downstream portion of the drainage passage and connecting the upstream portion and the downstream portion of the drainage passage; a collector provided midway through the collection passage and collecting fine particles contained in the cooling water that flows through the collection passage from the upstream portion of the drainage passage to the downstream portion of the drainage passage; a bypass passage connected in parallel to the collection passage between the upstream portion and the downstream portion of the drainage passage; and a separation section at which the upstream portion of the drainage passage branches into the collection passage and the bypass passage. the drain passage includes a branch portion, and a junction portion where the collection passage and the bypass passage join at a downstream portion of the drain passage, the upstream portion of the drain passage, the collection passage, and the bypass passage are arranged so that a difference between a flow direction of the cooling water flowing from the upstream portion of the drain passage into the branch portion and a flow direction of the cooling water flowing from the branch portion into the collection passage is smaller than a difference between a flow direction of the cooling water flowing from the upstream portion of the drain passage into the branch portion and a flow direction of the cooling water flowing from the branch portion into the bypass passage, and the downstream portion of the drain passage, the collection passage, and the bypass passage are arranged so that a difference between a flow direction of the cooling water flowing from the bypass passage into the junction portion and a flow direction of the cooling water flowing from the junction portion into the downstream portion of the drain passage is smaller than a difference between a flow direction of the cooling water flowing from the collection passage into the junction portion and a flow direction of the cooling water flowing from the junction portion into the downstream portion of the drain passage The upstream portion of the drain passage has a curved portion, and the downstream end of the curved portion is connected to the inlet portion of the branching portion, and the bypass passage branches off to the side facing the outer surface of the radially inner wall of the curved portion. . A second cooling device for a marine propulsion unit of the present invention is provided in a marine propulsion unit, and is configured to take in water from outside the marine propulsion unit into the marine propulsion unit, and cool the power source by causing the taken-in water to flow around or inside the power source as cooling water, and to discharge the cooling water after flowing around or inside the power source to the outside of the marine propulsion unit, and is configured to include a drainage passage for discharging the cooling water after flowing around or inside the power source to the outside of the marine propulsion unit, and a drainage passage between an upstream portion and a downstream portion of the drainage passage. a collecting passage interposed between the upstream and downstream portions of the drain passage and connecting the upstream and downstream portions of the drain passage; a collector provided midway through the collecting passage and configured to collect fine particles contained in the cooling water flowing through the collecting passage from the upstream portion of the drain passage toward the downstream portion of the drain passage; a bypass passage connected in parallel to the collecting passage between the upstream and downstream portions of the drain passage; a branching portion where the upstream portion of the drain passage branches into the collecting passage and the bypass passage; and a junction portion where the collecting passage and the bypass passage merge into the downstream portion of the drain passage. The upstream portion of the drainage passage, the collection passage, and the bypass passage are arranged so that a difference between a flow direction of the cooling water flowing from the upstream portion of the drainage passage into the branching portion and a flow direction of the cooling water flowing from the branching portion into the collection passage is smaller than a difference between a flow direction of the cooling water flowing from the upstream portion of the drainage passage into the branching portion and a flow direction of the cooling water flowing from the branching portion into the bypass passage, and the downstream portion of the drainage passage, the collection passage, and the bypass passage are arranged so that a difference between a flow direction of the cooling water flowing from the bypass passage to the junction portion and a flow direction of the cooling water flowing from the bypass passage to the junction portion is smaller than a difference between a flow direction of the cooling water flowing from the upstream portion of the drainage passage into the branching portion and a flow direction of the cooling water flowing from the branching portion into the bypass passage. The drain passage is arranged so that the difference between the flow direction of the cooling water flowing into the collection passage from the collection passage and the flow direction of the cooling water flowing from the confluence into the downstream part of the drain passage is smaller than the difference between the flow direction of the cooling water flowing from the collection passage to the confluence and the flow direction of the cooling water flowing from the confluence into the downstream part of the drain passage, the upstream part of the drain passage has a bent part bent in an arc shape, the downstream end of the bent part is connected to the inlet part of the branch part, and the bypass passage extends from the branch part to the side where the center of the arc of the bent part is located. [Effects of the Invention]

[0016] According to the present invention, even without using a valve or the like that opens and closes the bypass passage depending on whether the collector is clogged or not, it is possible to ensure sufficient fine object collection capacity. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is an overall view showing an outboard motor provided with a cooling device according to an embodiment of the present invention; [Figure 2] 1 is an external view showing an engine of an outboard motor according to an embodiment of the present invention as viewed from the left side. FIG. [Figure 3] FIG. 3 is an external view showing the engine in FIG. 2 as seen from the rear. [Figure 4] 1 is an explanatory diagram showing the configuration of a cooling device according to an embodiment of the present invention; [Figure 5] 1 is an explanatory diagram showing the basic configuration of a fine object collecting device in a cooling device according to an embodiment of the present invention; [Figure 6] 6 is a cross-sectional view taken along the line VI-VI in FIG. 3, showing the upstream portion of the drainage passage, the fine object collecting device, and the downstream portion of the drainage passage. [Figure 7] 7 is an enlarged cross-sectional view of the case and the filter cartridge in FIG. 6. FIG. [Figure 8] FIG. 10 is an explanatory diagram showing the configuration of the drainage side of a conventional cooling device. [Figure 9] FIG. 10 is an explanatory diagram showing a configuration of the drain side of a conventional cooling device from which a relief valve has been removed. DETAILED DESCRIPTION OF THE INVENTION

[0018] A cooling device for a marine propulsion unit according to an embodiment of the present invention is a cooling device that is installed in a marine propulsion unit, takes in water from outside the marine propulsion unit into the marine propulsion unit, flows the taken-in water around or inside the power source of the marine propulsion unit as cooling water to cool the power source, and discharges the cooling water after flowing around or inside the power source outside the marine propulsion unit.The cooling device is equipped with a drainage passage for discharging the cooling water after flowing around or inside the power source outside the marine propulsion unit, a collection passage interposed between the upstream and downstream portions of the drainage passage and connecting the upstream and downstream portions of the drainage passage, a collector installed in the middle of the collection passage and collecting fine particles contained in the cooling water that flows through the collection passage from the upstream portion of the drainage passage to the downstream portion of the drainage passage, a bypass passage connected in parallel to the collection passage between the upstream and downstream portions of the drainage passage, a branch section where the upstream portion of the drainage passage branches into the collection passage and the bypass passage, and a junction section where the collection passage and the bypass passage merge into the downstream portion of the drainage passage.

[0019] In addition, in the cooling device of this embodiment, the upstream portion of the drainage passage, the collection passage, and the bypass passage are arranged so that the difference in flow direction between the cooling water flowing from the upstream portion of the drainage passage into the branch portion and the cooling water flowing from the branch portion into the collection passage is smaller than the difference in flow direction between the cooling water flowing from the upstream portion of the drainage passage into the branch portion and the cooling water flowing from the branch portion into the bypass passage.

[0020] By arranging the upstream portion of the drainage passage, the collection passage, and the bypass passage in this manner, when the collector is not clogged, cooling water flowing out from the upstream portion of the drainage passage is more likely to flow into the collection passage than into the bypass passage. Therefore, without using a valve or the like that opens and closes the bypass passage depending on whether the collector is clogged, most of the cooling water flowing out from the upstream portion of the drainage passage can be smoothly directed into the collection passage and sent to the collector when the collector is not clogged. That is, even when the upstream portion of the drainage passage and the inlet of the bypass passage are always in communication, the cooling water flowing out from the upstream portion of the drainage passage can be prevented from flowing into the bypass passage when the collector is not clogged. Therefore, when the collector is not clogged, a decrease in the amount of cooling water flowing through the collector due to cooling water flowing into the bypass passage can be prevented, and a decrease in the cooling device's ability to collect fine objects can be prevented.

[0021] In addition, in the cooling device of this embodiment, the downstream portion of the drain passage, the collection passage, and the bypass passage are arranged so that the difference between the flow direction of the cooling water flowing from the bypass passage into the confluence and the flow direction of the cooling water flowing from the confluence into the downstream portion of the drain passage is smaller than the difference between the flow direction of the cooling water flowing from the collection passage into the confluence and the flow direction of the cooling water flowing from the confluence into the downstream portion of the drain passage.

[0022] By arranging the downstream portion of the drainage passage, the collection passage, and the bypass passage in this manner, the flow direction of cooling water from the bypass passage to the downstream portion of the drainage passage can be made nearly linear or straight. Therefore, when the collector is clogged, cooling water can be smoothly flowed from the bypass passage to the downstream portion of the drainage passage, and the cooling water that has flowed through the bypass passage can be prevented from flowing back through the collection passage. Furthermore, by arranging the downstream portion of the drainage passage, the collection passage, and the bypass passage in this manner, when exhaust gas flows back from the exhaust chamber of the marine propulsion device through the downstream portion of the drainage passage, the flow direction of the exhaust gas from the downstream portion of the drainage passage to the bypass passage can be made nearly linear or straight, and the flow direction of the exhaust gas from the downstream portion of the drainage passage to the collection passage can be curved. Therefore, exhaust gas that flows back through the downstream portion of the drainage passage from the exhaust chamber of the marine propulsion device can be smoothly flowed into the bypass passage, and the exhaust gas that flows back through the downstream portion of the drainage passage can be prevented from flowing back through the collection passage.

[0023] In this way, by suppressing the backflow of cooling water or exhaust gas into the collection passage, it is possible to suppress the stirring up of fine particles accumulated in the collector due to the cooling water or exhaust gas passing from bottom to top through the collector. Therefore, even if the inlet of the collection passage and the inlet of the bypass passage are always connected at the branching portion, it is possible to suppress the stirring up of fine particles once accumulated in the collector and discharging them outside the marine propulsion device through the downstream portion of the bypass passage and the drainage passage. As such, according to this embodiment, even if a valve or the like is not provided to open or close the bypass passage depending on whether the collector is clogged, it is possible to suppress the stirring up of fine particles once accumulated in the collector due to the backflow of cooling water or exhaust gas and discharging them outside the marine propulsion device, thereby ensuring sufficient fine particle collection capacity of the cooling device. [Example]

[0024] Hereinafter, an embodiment of a cooling device for a marine propulsion unit of the present invention will be described with reference to Figures 1 to 7. In the embodiments, when directions such as front (Fd), rear (Bd), top (Ud), bottom (Dd), left (Ld), and right (Rd) are described, they will be referred to by the arrows drawn at the bottom left of Figures 1 to 7.

[0025] (Outboard motor) FIG. 1 shows an outboard motor 1, one type of marine propulsion device, as viewed from the left. As shown in FIG. 1, the outboard motor 1 includes an engine 2 as a power source, a drive shaft 3 that rotates with power from the engine 2, a propeller 4 that generates propulsive force for the marine vessel, a propeller shaft 5 to which the propeller 4 is attached, and a gear mechanism 6 that transmits the rotation of the drive shaft 3 to the propeller shaft 5. Although not shown, the gear mechanism 6 is also provided with a shift device that switches the direction of rotation transmitted from the drive shaft 3 to the propeller shaft 5. The engine 2 is located at the top of the outboard motor 1. The gear mechanism 6, the propeller shaft 5, and the propeller 4 are located at the bottom of the outboard motor 1. The drive shaft 3 extends vertically between the engine 2 and the gear mechanism 6.

[0026] The lower part of the engine 2 is covered by an engine bottom cover 7, and the vertical middle and upper parts of the engine 2 are covered by an engine top cover 8. The engine top cover 8 is detachably attached to the engine bottom cover 7. By removing the engine top cover 8, a wide range of the engine 2 from the vertical middle to the upper part can be exposed. The upper part of the drive shaft 3 is covered by an upper case 9, and the vertical middle part of the drive shaft 3 is covered by a middle case 10. The lower part of the drive shaft 3 and the front part of the gear mechanism 6 and propeller shaft 5 are covered by a lower case 11.

[0027] FIG. 2 shows the engine 2 as seen from the left. FIG. 3 shows the engine 2 as seen from the rear. The engine 2 is, for example, a four-stroke, four-cylinder gasoline engine, and is cooled by water. The engine 2 is arranged so that the extension direction of the crankshaft is the vertical direction. As shown in FIG. 2, the engine 2 has a crankcase 12 arranged at the front, a cylinder block 13 arranged behind the crankcase 12, and a cylinder head 14 arranged behind the cylinder block 13. The rear of the cylinder head 14 is covered by a cylinder head cover 15.

[0028] As shown in FIG. 1 , the outboard motor 1 is provided with an exhaust passage 16 for discharging exhaust gas emitted from the engine 2 outside the outboard motor 1. The upper end of the exhaust passage 16 is connected to an exhaust port provided in the cylinder head 14 of the engine 2, and the lower end of the exhaust passage 16 is connected to an exhaust chamber 17 provided in the rear lower part of the outboard motor 1. In the outboard motor 1 of this embodiment, the exhaust chamber 17 is provided in a section extending from the rear of the middle case 10 to the rear of the lower case 11. Exhaust gas discharged from an exhaust port of the engine 2 is sent to the exhaust chamber 17 via the exhaust passage 16, and then discharged outside the outboard motor 1 through an outlet provided in, for example, the shaft of the propeller 4. Note that the exhaust port of the engine 2 and the exhaust passage 16 are not shown in FIGS. 2 and 3 .

[0029] (cooling device) The outboard motor 1 is equipped with a cooling device 21 that uses the water around the outboard motor 1, such as seawater, lake water, or river water, as cooling water to cool the engine 2 and other heat-generating parts of the outboard motor 1. Figure 4 shows the configuration of the cooling device 21.

[0030] As shown in FIG. 4, the cooling device 21 includes a water intake port 22, a water intake passage 23, a water pump 24, a water supply passage 25, a water jacket 26, a drain passage 27, a thermostat 28, a pressure valve 29, and a fine object collecting device 31.

[0031] The water intake 22 is an opening for taking in water around the outboard motor 1 into the outboard motor 1, and is provided in a portion of the outboard motor 1 that is submerged underwater, specifically in a part of the lower case 11 (see FIG. 1). The water intake 22 is also provided with a strainer or a cover with many small holes to prevent stones, algae, and other objects larger than minute particles from entering the outboard motor 1 along with seawater, lake water, or river water.

[0032] The water intake passage 23 is a passage for sucking water taken into the outboard motor 1 through the water intake port 22 into the water pump 24, and is provided inside the lower case 11.

[0033] The water pump 24 is a pump that sucks water taken into the outboard motor 1 through the water intake 22 and discharges the sucked water as cooling water, and is provided, for example, inside the lower case 11 or the middle case 10. The water pump 24 is operated using the rotation of the drive shaft 3.

[0034] The water supply passage 25 is a passage for supplying the cooling water discharged from the water pump 24 to the water jacket 26, and is formed, for example, by hoses or pipes provided inside the middle case 10, upper case 9, and engine bottom cover 7.

[0035] The water jacket 26 is a mechanism for cooling the engine 2 by causing the cooling water fed through the water supply passage 25 to flow around or inside the engine 2, and is provided around or inside the engine 2.

[0036] The drain passage 27 is a passage for discharging the cooling water outside the outboard motor 1 after it has flowed through the water jacket 26, and is formed by, for example, a hose or pipe provided inside the engine top cover 8, the engine bottom cover 7, and the upper case 9. A fine object collecting device 31 is interposed midway through the drain passage 27, and therefore the drain passage 27 is divided into an upstream section 27A, which is the section upstream of the fine object collecting device 31, and a downstream section 27B, which is the section downstream of the fine object collecting device 31.

[0037] As shown in FIGS. 2 and 3 , the upstream portion 27A of the drain passage 27 is located in an area extending from above the cylinder head 14 to the upper left of the cylinder head cover 15. The upstream portion 27A of the drain passage 27 is formed of a heat-resistant and highly rigid resin pipe or a corrosion-resistant metal pipe, or a heat-resistant and highly rigid rubber hose. The upper end of the upstream portion 27A of the drain passage 27 is connected to the outlet 26A of the water jacket 26 located at the top of the cylinder head 14. The upstream portion 27A of the drain passage 27 extends leftward from the outlet 26A of the water jacket 26 and then bends. Then, the upstream portion 27A extends rearward while sloping downward on the left side of the upper rear portion of the engine 2 and then bends again. Then, the upstream portion 27A extends horizontally rearward on the left side of the upper rear portion of the engine 2 and then bends again. Then, the downstream portion 27A extends vertically downward on the left side of the upper rear portion of the engine 2. The lower end of the upstream portion 27A of the drain passage 27 faces downward. In addition, the lower end of the upstream portion 27A of the drainage passage 27 is connected to the upper end of the collection passage 32 and bypass passage 34 of the fine object collection device 31 (specifically, the upper end of the inlet pipe portion 41A of the branch pipe 41).

[0038] The downstream portion 27B of the drain passage 27 is disposed in an area extending from the lower left rear portion of the engine 2 to the exhaust chamber 17. The upper end of the downstream portion 27B of the drain passage 27 is formed by a drain hole 30 formed in the lower left rear portion of the housing of the engine 2. The drain hole 30 extends downward while being slightly inclined to the right, and the upper opening of the drain hole 30 faces upward. The upper end of the drain hole 30 is connected to the lower ends of the collection passage 32 and the bypass passage 34 (specifically, the lower end of the outflow pipe portion 54C of the junction pipe 54). The portion of the downstream portion 27B of the drain passage 27 below the drain hole 30 is formed by a hose or pipe provided inside the engine bottom cover 7, upper case 9, etc. The lower end of the downstream portion of the drain passage 27 is connected to the exhaust chamber 17 as shown in FIG. 4.

[0039] The thermostat 28 is a device that limits the flow of coolant to warm up the engine 2 or to prevent the engine 2 from overcooling, and is provided, for example, near the outlet 26A of the water jacket 26. The thermostat 28 opens when the temperature of the coolant flowing through the water jacket 26 reaches or exceeds a predetermined reference temperature, and closes when the temperature of the coolant falls below the reference temperature.

[0040] Pressure valve 29 is a valve that reduces the water pressure in water supply passage 25 or water jacket 26 by allowing the water coolant discharged from water pump 24 to escape toward exhaust chamber 17 when the flow of water coolant is restricted by thermostat 28. Pressure valve 29 is, for example, a normally closed valve, and opens when the water pressure in water supply passage 25 exceeds a predetermined reference pressure.

[0041] The fine matter collecting device 31 is a device that collects fine matter contained in seawater, lake water, river water, or the like that is taken into the outboard motor 1 from outside and used as cooling water to cool the engine 2. The fine matter collecting device 31 will be described in detail later.

[0042] In the cooling system 21 configured as described above, when the water pump 24 is operating, the thermostat 28 is open, and the pressure valve 29 is closed, water around the outboard motor 1 is taken into the outboard motor 1 through the water intake 22, flows sequentially through the water intake passage 23 and the water supply passage 25, and is sent to the water jacket 26 as cooling water. The cooling water sent to the water jacket 26 flows within the water jacket 26, thereby cooling the engine 2. The cooling water that has flowed through the water jacket 26 flows from the outlet 26A of the water jacket 26 into the upstream section 27A of the water drain passage 27, flows through the upstream section 27A of the water drain passage 27, then flows through the fine object collecting device 31, and then flows through the downstream section 27B of the water drain passage 27, and is then discharged into the exhaust chamber 17. The cooling water discharged into the exhaust chamber 17 is discharged together with exhaust gases to the outside of the outboard motor 1, for example, through an outlet provided on the shaft of the propeller 4. On the other hand, when the water pump 24 is operating, the thermostat 28 is closed, and the pressure valve 29 is open, water taken into the outboard motor 1 from the water intake 22 flows sequentially through the water intake passage 23 and the water supply passage 25, but before reaching the water jacket 26, it is sent to the exhaust chamber 17 side via the open pressure valve 29 and released into the exhaust chamber 17. The cooling water released into the exhaust chamber 17 is discharged outside the outboard motor 1 together with the exhaust gas.

[0043] (Fine object collection device) As described above, the fine matter collecting device 31 is a device that collects fine matter contained in seawater, lake water, river water, etc. that is taken into the outboard motor 1 from outside and used as cooling water to cool the engine 2. As shown in Figures 2 and 3, the fine matter collecting device 31 is disposed on the left side of the rear of the engine 2. The fine matter collecting device 31 is also disposed inside the engine top cover 8.

[0044] The fine objects are, for example, microscopic trash such as microplastics, or residue from aquaculture feed. The size of the fine objects is, for example, approximately 0.1 mm or more and approximately 5 mm or less. Because of their size, the fine objects cannot be removed by a strainer or a cover with numerous small holes provided on the water intake 22. That is, when the water pump 24 is operating, the thermostat 28 is open, and the pressure valve 29 is closed, the fine objects enter the outboard motor 1 through the water intake 22 along with seawater, lake water, river water, or the like, and then flow into the fine object collection device 31 through the water intake passage 23, the water supply passage 25, the water jacket 26, and the upstream portion 27A of the water discharge passage 27.

[0045] Fig. 5 shows the basic configuration of the fine object collecting device 31. As shown in Fig. 5, the fine object collecting device 31 includes a collecting passage 32, a collector 33, a bypass passage 34, a branching section 35, and a junction section 36.

[0046] The collection passage 32 is a passage that is interposed between the upstream portion 27A and the downstream portion 27B of the drainage passage 27 and connects the upstream portion 27A and the downstream portion 27B of the drainage passage 27. The collection passage 32 causes the cooling water flowing through the upstream portion 27A of the drainage passage 27 to flow to the downstream portion 37B of the drainage passage 27 via the collector 33.

[0047] The collector 33 is provided midway through the collection passage 32 and is a device that captures fine objects contained in the cooling water that flows through the collection passage 32 from the upstream portion 27A of the drain passage 27 toward the downstream portion 27B of the drain passage 27. As will be described later, the collector 33 captures fine objects in the cooling water by passing the cooling water flowing through the collection passage 32 through a filter 43, thereby removing the fine objects from the cooling water.

[0048] The bypass passage 34 is a passage connected in parallel to the collection passage 32 between the upstream portion 27A and the downstream portion 27B of the drainage passage 27. When the filter 43 of the collector 33 becomes clogged, for example, the bypass passage 34 directs the cooling water flowing through the upstream portion 27A of the drainage passage 27 to the downstream portion 37B of the drainage passage 27 without passing through the collector 33.

[0049] Branching section 35 is a section where upstream section 27A of drainage passage 27 branches into collection passage 32 and bypass passage 34. Confluence section 36 is a section where collection passage 32 and bypass passage 34 merge into downstream section 27B of drainage passage 27.

[0050] (Arrangement of collection passages and bypass passages at branching points) In Figure 5, the upstream portion 27A of the drainage passage 27, the collection passage 32, and the bypass passage 34 are arranged so that the difference between the flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 into the branch portion 35 and the flow direction of the cooling water flowing from the branch portion 35 into the collection passage 32 is smaller than the difference between the flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 into the branch portion 35 and the flow direction of the cooling water flowing from the branch portion 35 into the bypass passage 34.

[0051] Specifically, the upstream portion 27A of the drainage passage 27 and the collection passage 32 are arranged so that the flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 into the branch portion 35 is the same as the flow direction of the cooling water flowing from the branch portion 35 into the collection passage 32. In contrast, the upstream portion 27A of the drainage passage 27 and the bypass passage 34 are arranged so that the flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 into the branch portion 35 is different from the flow direction of the cooling water flowing from the branch portion 35 into the bypass passage 34.

[0052] More specifically, upstream portion 27A of drainage passage 27 is arranged so that the flow direction of cooling water flowing from upstream portion 27A of drainage passage 27 into branch portion 35 is downward and vertical, as indicated by arrow A. Furthermore, collection passage 32 is arranged so that the flow direction of cooling water flowing from branch portion 35 into collection passage 32 is downward and vertical, as indicated by arrow B. In contrast, bypass passage 34 is arranged so that the flow direction of cooling water flowing from branch portion 35 into bypass passage 34 is not vertical, as indicated by arrow C.

[0053] In this embodiment, the lower end of the upstream portion 27A of the drain passage 27 and the upper end of the collection passage 32, which are connected to each other at the branch portion 35, both extend vertically and are arranged coaxially. As a result, a linear flow path extending vertically is formed from the lower end of the upstream portion 27A of the drain passage 27 to the upper end of the collection passage 32. In contrast, the upper end of the bypass passage 34, which is connected to the lower end of the upstream portion 27A of the drain passage 27 at the branch portion 35, is inclined relative to the vertical. As a result, a curved flow path is formed from the lower end of the upstream portion 27A of the drain passage 27 to the upper end of the bypass passage 34.

[0054] Furthermore, at the branching portion 35, the collection passage 32 and the bypass passage 34 intersect with each other at an acute angle. The angle P formed between the upper end of the collection passage 32 and the upper end of the bypass passage 34 is, for example, approximately 20 degrees or more and less than 90 degrees. Note that the upper end of the bypass passage 34 may extend horizontally so that the collection passage 32 and the bypass passage 34 intersect with each other at a right angle at the branching portion 35; in this case, the angle P becomes 90 degrees.

[0055] (Arrangement of collection passages and bypass passages at confluences) The collection passage 32, the bypass passage 34, and the downstream portion 27B of the drain passage 27 are arranged so that the difference between the flow direction of the cooling water flowing from the bypass passage 34 to the confluence 36 and the flow direction of the cooling water flowing from the confluence 36 to the downstream portion 27B of the drain passage 27 is smaller than the difference between the flow direction of the cooling water flowing from the collection passage 32 to the confluence 36 and the flow direction of the cooling water flowing from the confluence 36 to the downstream portion 27B of the drain passage 27.

[0056] Specifically, the bypass passage 34 and the downstream portion 27B of the drain passage 27 are arranged so that the flow direction of the cooling water flowing from the bypass passage 34 into the junction 36 is approximately the same as the flow direction of the cooling water flowing from the junction 36 into the downstream portion 27B of the drain passage 27. In contrast, the collection passage 32 and the downstream portion 27B of the drain passage 27 are arranged so that the flow direction of the cooling water flowing from the collection passage 32 into the junction 36 is different from the flow direction of the cooling water flowing from the junction 36 into the downstream portion 27B of the drain passage 27.

[0057] The reason why the relationship between the flow direction of the cooling water flowing from the bypass passage 34 into the junction 36 and the flow direction of the cooling water flowing from the junction 36 into the downstream portion 27B of the drain passage 27 is described as "substantially the same" is because, as shown in Fig. 3, when the engine 2 is viewed from the rear, the upper end (drain hole 30) of the downstream portion 27B of the drain passage 27 is inclined slightly to the right with respect to the vertical. The fact that the upper end of the downstream portion 27B of the drain passage 27 is inclined slightly to the right with respect to the vertical does not substantially reduce the effect of the cooling device 21 of this embodiment, that is, the ability to prevent the cooling water that has flowed through the bypass passage 34 from flowing back into the collection passage 32, nor does it substantially reduce the effect of the cooling device 21 of this embodiment, that is, the ability to prevent exhaust gas that has flowed back from the exhaust chamber 17 from flowing into the collection passage 32 from the lower end of the collection passage 32.

[0058] More specifically, the bypass passage 34 is arranged so that the flow direction of the cooling water flowing from the bypass passage 34 into the junction 36 is downward and vertical, as indicated by arrow E. Furthermore, the downstream portion 27B of the drain passage 27 is arranged so that the flow direction of the cooling water flowing from the junction 36 into the downstream portion 27B of the drain passage 27 is downward and approximately vertical, as indicated by arrow F. In contrast, the collection passage 32 is arranged so that the flow direction of the cooling water flowing from the collection passage 32 into the junction 36 is not vertical, as indicated by arrow D.

[0059] In this embodiment, the lower end of the bypass passage 34 and the upper end of the downstream portion 27B of the drain passage 27 are connected to each other at the junction 36, the lower end of the bypass passage 34 extends vertically, the upper end of the downstream portion 27B of the drain passage 27 extends approximately vertically, and the lower end of the bypass passage 34 and the upper end of the downstream portion 27B of the drain passage 27 are arranged approximately coaxially with each other. As a result, a substantially straight flow path extending approximately vertically is formed from the lower end of the bypass passage 34 to the upper end of the downstream portion 27B of the drain passage 27. In contrast, the lower end of the collection passage 32 connected to the upper end of the downstream portion 27B of the drain passage 27 at the junction 36 is inclined with respect to the vertical. As a result, a curved flow path is formed from the lower end of the collection passage 32 to the upper end of the downstream portion 27B of the drain passage 27.

[0060] Furthermore, at the junction 36, the collection passage 32 and the bypass passage 34 intersect with each other at an acute angle. The angle Q between the lower end of the collection passage 32 and the lower end of the bypass passage 34 is, for example, equal to or greater than approximately 20 degrees and less than 90 degrees. Note that the lower end of the collection passage 32 may extend horizontally so that the collection passage 32 and the bypass passage 34 intersect with each other at a right angle at the junction 36; in this case, Q becomes 90 degrees.

[0061] The collection passage 32 extends vertically downward from the branching portion 35, then bends, and then extends downward while inclined relative to the vertical, reaching the confluence portion 36. The collector 33 is provided midway along the vertically extending portion of the collection passage 32. The bypass passage 34 extends downward from the branching portion 35 while inclined relative to the vertical, then bends, and then extends vertically downward, reaching the confluence portion 36.

[0062] (Flow of cooling water in the fine object collection device) In FIG. 5 , the lower end of the upstream portion 27A of the drainage passage 27 and the upper end of the collection passage 32 both extend vertically. The lower end of the upstream portion 27A of the drainage passage 27 and the upper end of the collection passage 32 are coaxially arranged, forming a linear flow path extending vertically from the lower end of the upstream portion 27A of the drainage passage 27 to the upper end of the collection passage 32. Therefore, the flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 to the branch portion 35 and the flow direction of the cooling water flowing from the branch portion 35 to the collection passage 32 are both downward and vertical, as indicated by arrows A and B, and are the same. In contrast, the upper end of the bypass passage 34 is inclined relative to the vertical, forming a curved flow path from the lower end of the upstream portion 27A of the drainage passage 27 to the upper end of the bypass passage 34. Therefore, the flow direction of the cooling water flowing from the branch portion 35 to the bypass passage 34 is not vertical, as indicated by arrow C. As a result, the flow direction of the cooling water flowing from the upstream portion 27A of the drain passage 27 into the branch portion 35 differs from the flow direction of the cooling water flowing from the branch portion 35 into the bypass passage 34. Therefore, when the filter 43 of the collector 33 is not clogged, most of the cooling water flowing from the upstream portion 27A of the drain passage 27 into the branch portion 35 flows into the collection passage 32. The cooling water that flows into the collection passage 32 passes through the filter 43 in the collector 33. As the cooling water passes through the filter 43, fine particles in the cooling water are removed. The cooling water that has passed through the filter 43 flows into the downstream portion 27B of the drain passage 27, sequentially passing through the lower part of the collection passage 32 and the junction portion 36. Thus, according to this embodiment, when the filter 43 of the collector 33 is not clogged, most of the cooling water flowing out from the upstream portion 27A of the drainage passage 27 can be made to flow into the collection passage 32 and sent to the collector 33 without using a valve or the like that opens and closes the bypass passage 34 depending on whether the filter 43 of the collector 33 is clogged or not.

[0063] On the other hand, if the filter 43 of the collector 33 is clogged, it becomes difficult for the cooling water to pass through the filter 43, and the flow of cooling water is stagnated within the collector 33 and in the upper part of the collection passage 32 (the part above the collector 33). Therefore, if the filter 43 of the collector 33 is clogged, most of the cooling water that flows from the upstream part 27A of the drain passage 27 into the branch part 35 flows into the bypass passage 34, passes through the bypass passage 34 and the junction part 36 in that order, and flows into the downstream part 27B of the drain passage 27. Here, the lower end of the bypass passage 34 extends vertically, the upper end of the downstream part 27B of the drain passage 27 extends approximately vertically, and the lower end of the bypass passage 34 and the upper end of the downstream part 27B of the drain passage 27 are arranged approximately coaxially with each other. As a result, a substantially linear flow path extending approximately vertically is formed from the lower end of the bypass passage 34 to the upper end of the downstream part 27B of the drain passage 27. Therefore, the flow direction of the cooling water flowing from the bypass passage 34 into the junction 36 and the flow direction of the cooling water flowing from the junction 36 into the downstream portion 27B of the drain passage 27 are both downward and approximately vertical, as indicated by arrows E and F, and are approximately the same. Therefore, the cooling water flows smoothly downward in an approximately straight line and approximately vertically from the bypass passage 34 to the downstream portion 27B of the drain passage 27. Therefore, according to this embodiment, it is possible to prevent the flow of the cooling water flowing from the bypass passage 34 into the junction 36 from being disturbed and flowing back through the collection passage 32 from the lower end of the bypass passage 34. Therefore, it is possible to prevent the cooling water from passing from bottom to top inside the collector 33 from stirring up fine objects accumulated in the filter 43 of the collector 33.

[0064] (Flow of exhaust gases flowing back from the exhaust chamber) As can be seen from FIGS. 1 and 4 , the exhaust passage 16 and the downstream portion 27B of the drain passage 27 are connected to the exhaust chamber 17 of the outboard motor 1. As a result, the exhaust passage 16 and the downstream portion 27B of the drain passage 27 are connected via the exhaust chamber 17. Therefore, when the pressure in the downstream portion 27B of the drain passage 27 becomes lower than the pressure in the exhaust chamber 17, exhaust gas sent from the exhaust passage 16 to the exhaust chamber 17 may flow from the exhaust chamber 17 into the downstream portion 27B of the drain passage 27 and backflow through the downstream portion 27B of the drain passage 27. In the outboard motor 1, the lower end of the bypass passage 34 and the upper end of the downstream portion 27B of the drain passage 27 both extend approximately vertically. Furthermore, the lower end of the bypass passage 34 and the upper end of the downstream portion 27B of the drain passage 27 are arranged approximately coaxially with each other, forming a substantially linear flow path that extends approximately vertically from the lower end of the bypass passage 34 to the upper end of the downstream portion 27B of the drain passage 27. Therefore, most of the exhaust gas that flows back through the downstream portion 27B of the drainage passage 27 flows in a substantially straight line from bottom to top along this substantially linear flow path. That is, most of the back-flowing exhaust gas flows smoothly from the downstream portion 27B of the drainage passage 27 into the bypass passage 34. The exhaust gas that flows into the bypass passage 34 flows from bottom to top through the bypass passage 34, and then flows through the branch portion 35 to the upstream portion 27A of the drainage passage 27. In this way, according to this embodiment, it is possible to prevent the exhaust gas that flows back through the downstream portion 27B of the drainage passage 27 from flowing into the collection passage 32, and the back-flowing exhaust gas passes from bottom to top through the collector 33, thereby preventing fine objects accumulated in the filter 43 of the collector 33 from being stirred up.

[0065] (Details of the configuration of the fine object collection device) Figure 6 shows the details of the configuration of the fine object collector 31, and shows a cross section of the upstream portion 27A of the drainage passage 27, the fine object collector 31, and the upper end of the downstream portion 27B of the drainage passage 27 taken along the section line VI-VI in Figure 3, viewed from the left. Figure 7 shows an enlarged view of the collector 33 in Figure 6.

[0066] 6, the fine object collecting device 31 specifically includes a branch pipe 41, a collector 33, a connection hose 51, a bypass pipe 52, a connecting pipe 53, and a junction pipe 54. The first outlet pipe section 41B of the branch pipe 41, the connecting hose 51, and the first inlet pipe section 54A of the junction pipe 54 form a collection passage 32. The second outlet pipe section 41C of the branch pipe 41, the bypass pipe 52, the connecting pipe 53, and the second inlet pipe section 54B of the junction pipe 54 form a bypass passage 34. In the branch pipe 41, the portion where the inlet pipe section 41A branches into the first outlet pipe section 41B and the second outlet pipe section 41C corresponds to the branch section 35. In the junction pipe 54, the portion where the first inlet pipe section 54A and the second inlet pipe section 54B join the outlet pipe section 54C corresponds to the junction section 36.

[0067] The branch pipe 41 connects the upstream portion 27A of the drain passage 27 to the collector 33 and also connects the upstream portion 27A of the drain passage 27 to the bypass pipe 52. The branch pipe 41 is formed of a heat-resistant and rigid resin or a corrosion-resistant metal. The branch pipe 41 has an inlet pipe section 41A, a first outlet pipe section 41B, and a second outlet pipe section 41C. In the branch pipe 41, the inlet pipe section 41A is located on the upper side, and the first outlet pipe section 41B is located on the lower side. The inlet pipe section 41A and the first outlet pipe section 41B are arranged coaxially, and the portion of the branch pipe 41 from the inlet pipe section 41A to the first outlet pipe section 41B extends vertically in a straight line. The inlet pipe section 41A is also arranged coaxially with the lower end of the upstream portion 27A of the drain passage 27, and the upper end of the inlet pipe section 41A is connected to the lower end of the upstream portion 27A of the drain passage 27. The second outlet pipe section 41C extends forward while inclining downward from a substantially middle portion in the vertical direction of the portion of the branch pipe 41 extending from the inlet pipe section 41A to the first outlet pipe section 41B.

[0068] The collector 33 includes a filter cartridge 42 and a case 46. As shown in FIG. 7 , the filter cartridge 42 includes a filter 43 that captures fine particles and allows cooling water to pass through, and a holder 44 that holds the filter 43. The filter 43 is formed, for example, from a nonwoven fabric or a resin mesh, and is bag-shaped with an open top and a closed bottom. The holder 44 is formed, for example, from a heat-resistant and highly rigid resin or a highly corrosion-resistant metal, into a cylindrical shape with a vertically extending axis. The peripheral wall of the holder 44 is provided with multiple water passage holes 45. The filter 43 is disposed inside the holder 44 so as to cover each water passage hole 45 and the lower opening of the holder 44. The upper part of the filter 43 is attached to the inner peripheral surface of the upper part of the holder 44, for example, with an adhesive, and is fixed inside the holder 44 with the upper part of the filter 43 open upward.

[0069] The case 46 is a component that houses the filter cartridge 42. The case 46 is formed into a cylindrical shape with a vertically extending axis from a heat-resistant and highly rigid resin or a highly corrosion-resistant metal. The case 46 is divided into an upper case portion 47 that forms the upper part of the case 46 and a lower case portion 48 that forms the lower part of the case 46. The filter cartridge 42 is held between the upper case portion 47 and the lower case portion 48. The filter cartridge 42 is disposed coaxially with the case 46.

[0070] The lower end of the first outlet pipe portion 41B of the branch pipe 41 is connected to the upper opening of the upper case portion 47. In this embodiment, the upper case portion 47 is integrally formed with the first outlet pipe portion 41B of the branch pipe 41. In addition, a connecting pipe portion 49 is provided below the lower case portion 48, and the lower case portion 48 and the connecting pipe portion 49 are integral with each other.

[0071] The lower case portion 48 is separably connected to the upper case portion 47 by a connecting member 50. The connecting member 50 is formed in a cylindrical shape from, for example, resin or metal. The connecting member 50 is held on the outer periphery of the lower case portion 48 so as to be rotatable relative to the lower case portion 48 and movable up and down relative to the lower case portion 48. Threads are formed on the outer periphery of the lower end of the upper case portion 47 and on the inner periphery of the connecting member 50. The lower case portion 48 is connected to the upper case portion 47 by screwing the connecting member 50, which is rotatably held by the lower case portion 48, into the lower end of the upper case portion 47. The lower case portion 48 can be separated from the upper case portion 47 by rotating the connecting member 50 in a direction that loosens the threads and removing it from the lower end of the upper case portion 47.

[0072] The connection hose 51 is a pipe connecting the case 46 and the first inlet pipe portion 54A of the junction pipe 54. The connection hose 51 is made of a heat-resistant, highly rigid rubber hose. The connection hose 51 is highly rigid but flexible. As shown in FIG. 6 , the upper end of the connection hose 51 is arranged coaxially with the case 46 and connected to the lower end of the connection pipe portion 49 integrally formed with the lower case portion 48. The connection hose 51 extends vertically downward from its upper end, then gently bends, then extends downward while tilting to the right rear, then gently bends, and then extends downward while tilting to the left front. Because a portion of the connection hose 51 is inclined relative to the vertical in this manner, the connecting member 50 can be rotated in a direction that loosens the screws to make the lower case portion 48 separable from the upper case portion 47. The upper end of the connection hose 51 can then be grasped by hand and pushed down to separate the lower case portion 48 from the upper case portion 47. The filter cartridge 42 can be removed from the case 46 by separating the lower case part 48 from the upper case part 47. By removing the filter cartridge 42 from the case 46 in this manner, the user can remove fine objects accumulated on the filter 43.

[0073] The bypass pipe 52 is formed of a heat-resistant and highly rigid rubber hose, or a heat-resistant and highly rigid resin or corrosion-resistant metal pipe, etc. The upper end of the bypass pipe 52 is connected to the lower end of the second outflow pipe portion 41C of the branch pipe 41. The bypass pipe 52 extends downward from its upper end while tilting forward with respect to the vertical, then bends, and then extends vertically downward.

[0074] The connecting pipe 53 is made of a resin having high heat resistance and rigidity, or a metal having high corrosion resistance, etc. The connecting pipe 53 extends vertically and is arranged coaxially with the bypass pipe 52, and the upper end of the connecting pipe 53 is connected to the lower end of the bypass pipe 52.

[0075] The junction pipe 54 connects the connection hose 51 to the downstream portion 27B of the drain passage 27 and also connects the bypass pipe 52 to the downstream portion 27B of the drain passage 27 via the connecting pipe 53. The junction pipe 54 is formed of a heat-resistant and rigid resin or a corrosion-resistant metal. The junction pipe 54 has a first inlet pipe section 54A, a second inlet pipe section 54B, and an outlet pipe section 54C. In the junction pipe 54, the second inlet pipe section 54B is located on the upper side, and the outlet pipe section 54C is located on the lower side. The second inlet pipe section 54B and the outlet pipe section 54C are arranged coaxially, and the portion of the junction pipe 54 from the second inlet pipe section 54B to the outlet pipe section 54C extends vertically in a straight line. The second inlet pipe section 54B and the connecting pipe 53 are arranged coaxially with each other, and the lower end of the connecting pipe 53 is connected to the upper end of the second inlet pipe section 54B. Furthermore, the lower end of the outflow pipe section 54C is disposed approximately coaxially with the drain hole 30, which forms the upper end of the downstream section 27B of the drain passage 27, and the lower end of the outflow pipe section 54C is connected to the upper end of the drain hole 30. The first inflow pipe section 54A extends rearward while sloping upward and to the right from approximately the middle in the vertical direction of the section of the junction pipe 54 between the second inflow pipe section 54B and the outflow pipe section 54C. The lower end of the connection hose 51 is connected to the upper end of the first inflow pipe section 54A.

[0076] In addition, the inner diameters of the inlet pipe section 41A of the branch pipe 41, the first outlet pipe section 41B of the branch pipe 41, the second outlet pipe section 41C of the branch pipe 41, the connecting hose 51, the bypass pipe 52, the connecting pipe 53, the first inlet pipe section 54A of the junction pipe 54, the second inlet pipe section 54B of the junction pipe 54, and the outlet pipe section 54C of the junction pipe 54 are all approximately equal.

[0077] As described above, in the cooling device 21 of the outboard motor 1 according to the embodiment of the present invention, the upstream portion 27A of the drainage passage 27, the collection passage 32, and the bypass passage 34 are arranged so that the difference between the flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 into the branch portion 35 and the flow direction of the cooling water flowing from the branch portion 35 into the collection passage 32 is smaller than the difference between the flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 into the branch portion 35 and the flow direction of the cooling water flowing from the branch portion 35 into the bypass passage 34. By arranging the upstream portion 27A of the drainage passage 27, the collection passage 32, and the bypass passage 34 in this manner, when the filter 43 of the collector 33 is not clogged, the cooling water flowing out from the upstream portion 27A of the drainage passage 27 is more likely to flow into the collection passage 32 than into the bypass passage 34. Therefore, without using a valve or the like that opens and closes the bypass passage 34 depending on whether the filter 43 of the collector 33 is clogged, most of the cooling water that flows out from the upstream portion 27A of the drainage passage 27 when the filter 43 of the collector 33 is not clogged can be made to smoothly flow into the collection passage 32 and sent to the collector 33. In other words, even if the upstream portion 27A of the drainage passage 27 and the inlet of the bypass passage 34 are always in communication with each other, it is possible to prevent the cooling water that flows out from the upstream portion 27A of the drainage passage 27 when the filter 43 of the collector 33 is not clogged from flowing into the bypass passage 34. Therefore, when the filter 43 of the collector 33 is not clogged, it is possible to prevent the amount of cooling water flowing in the collector 33 from decreasing due to the cooling water flowing into the bypass passage 34, and it is possible to prevent a decrease in the ability of the cooling device 21 to collect fine objects.

[0078] Furthermore, in the cooling device 21 of this embodiment, the upstream portion 27A of the drainage passage 27 and the collection passage 32 are arranged so that the flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 into the branch portion 35 is the same as the flow direction of the cooling water flowing from the branch portion 35 into the collection passage 32, and the upstream portion 27A of the drainage passage 27 and the bypass passage 34 are arranged so that the flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 into the branch portion 35 is different from the flow direction of the cooling water flowing from the branch portion 35 into the bypass passage 34. With this configuration, when the filter 43 of the collector 33 is not clogged, most of the cooling water flowing out from the upstream portion 27A of the drainage passage 27 can flow more smoothly into the collection passage 32, thereby ensuring sufficient fine object collection capacity of the cooling device 21.

[0079] Furthermore, in the cooling device 21 of this embodiment, the upstream portion 27A of the drainage passage 27 is arranged so that the flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 into the branch portion 35 is downward and vertical, the collection passage 32 is arranged so that the flow direction of the cooling water flowing from the branch portion 35 into the collection passage 32 is downward and vertical, and the bypass passage 34 is arranged so that the flow direction of the cooling water flowing from the branch portion 35 into the bypass passage 34 is not vertical. With this configuration, when the filter 43 of the collector 33 is not clogged, most of the cooling water flowing out from the upstream portion 27A of the drainage passage 27 can flow more smoothly into the collection passage 32.

[0080] Furthermore, the collection passage 32 and the bypass passage 34 intersect at an acute angle at the branching portion 35. Therefore, when the filter 43 of the collector 33 is clogged, the cooling water that flows out from the upstream portion 27A of the drain passage 27 can smoothly flow into the bypass passage 34. This prevents the flow of cooling water in the drain passage 27 from deteriorating due to clogging of the filter 43 of the collector 33.

[0081] Furthermore, in the cooling device 21 of this embodiment, the collection passage 32, the bypass passage 34, and the downstream portion 27B of the drain passage 27 are arranged so that the difference between the flow direction of the cooling water flowing from the bypass passage 34 to the junction 36 and the flow direction of the cooling water flowing from the junction 36 to the downstream portion 27B of the drain passage 27 is smaller than the difference between the flow direction of the cooling water flowing from the collection passage 32 to the junction 36 and the flow direction of the cooling water flowing from the junction 36 to the downstream portion 27B of the drain passage 27. By arranging the downstream portion 27B of the drain passage 27, the collection passage 32, and the bypass passage 34 in this manner, the flow direction of the cooling water from the bypass passage 34 to the downstream portion 27B of the drain passage 27 can be made close to a straight line or made straight. Therefore, when the filter 43 of the collector 33 is clogged, the cooling water can be made to flow smoothly from the bypass passage 34 to the downstream portion 27B of the water discharge passage 27, and the cooling water that has flowed through the bypass passage 34 can be prevented from flowing into the collection passage 32 from the outlet of the collection passage 32 and flowing back through the collection passage 32. In addition, by arranging the downstream portion 27B of the water discharge passage 27, the collection passage 32, and the bypass passage 34 as described above, when exhaust gas flows back through the downstream portion 27B of the water discharge passage 27 from the exhaust chamber 17 of the outboard motor 1, the flow direction of the exhaust gas from the downstream portion 27B of the water discharge passage 27 to the bypass passage 34 can be made close to a straight line or made straight, and the flow direction of the exhaust gas from the downstream portion 27B of the water discharge passage 27 to the collection passage 32 can be bent. Therefore, exhaust gas that has flowed back from the exhaust chamber 17 through the downstream portion 27B of the water discharge passage 27 can be smoothly flowed into the bypass passage 34, and the exhaust gas that has flowed back through the downstream portion 27B of the water discharge passage 27 can be prevented from flowing into the collection passage 32 from the outlet of the collection passage 32 and flowing back through the collection passage 32. In this way, the backflow of cooling water or exhaust gas into the collection passage 32 can be prevented, and therefore fine matter accumulated in the filter 43 can be prevented from being stirred up when the cooling water or exhaust gas passes from bottom to top within the collector 33. Therefore, even if the inlet of the collection passage 32 and the inlet of the bypass passage 34 are always in communication with each other at the branch portion 35, fine matter that has accumulated in the filter 43 can be prevented from being stirred up and discharged to the outside of the outboard motor 1 through the bypass passage 34 and the downstream portion 27B of the water discharge passage 27.Thus, according to this embodiment, even if a valve or the like is not provided to open or close the bypass passage 34 depending on whether the filter 43 of the collector 33 is clogged or not, it is possible to prevent fine particles that have accumulated in the filter 43 from being discharged outside the outboard motor 1 due to backflow of cooling water or exhaust gas, and therefore the cooling device 21's ability to collect fine particles can be sufficiently ensured.

[0082] Furthermore, in the cooling device 21 of this embodiment, the bypass passage 34 and the downstream portion 27B of the drainage passage 27 are arranged so that the flow direction of the cooling water flowing from the bypass passage 34 into the junction 36 and the flow direction of the cooling water flowing from the junction 36 into the downstream portion 27B of the drainage passage 27 are substantially the same, and the collection passage 32 and the downstream portion 27B of the drainage passage 27 are arranged so that the flow direction of the cooling water flowing from the collection passage 32 into the junction 36 and the flow direction of the cooling water flowing from the junction 36 into the downstream portion 27B of the drainage passage 27 are different from each other. This configuration can improve the smoothness of the flow of cooling water flowing from the bypass passage 34 to the downstream portion 27B of the drainage passage 27 when the filter 43 of the collector 33 is clogged, and can also improve the smoothness of the flow of exhaust gas flowing back from the downstream portion 27B of the drainage passage 27 to the bypass passage 34. Therefore, the effect of suppressing the backflow of cooling water or exhaust gas into the collection passage 32 can be improved, and the effect of suppressing the stirring up of fine objects accumulated on the filter 43 can be improved.

[0083] Furthermore, in the cooling device 21 of this embodiment, the bypass passage 34 is arranged so that the flow direction of the cooling water flowing from the bypass passage 34 into the junction 36 is downward and vertical, the downstream portion 27B of the drain passage 27 is arranged so that the flow direction of the cooling water flowing from the junction 36 into the downstream portion 27B of the drain passage 27 is downward and approximately vertical, and the collection passage 32 is arranged so that the flow direction of the cooling water flowing from the collection passage 32 into the junction 36 is not vertical. This configuration further improves the smoothness of the flow of cooling water flowing from the bypass passage 34 to the downstream portion 27B of the drain passage 27 when the filter 43 of the collector 33 is clogged. Therefore, the effect of suppressing backflow of cooling water into the collection passage 32 can be further improved.

[0084] Furthermore, at the junction 36, the collection passage 32 and the bypass passage 34 intersect with each other at an acute angle. Therefore, when the filter 43 of the collector 33 is not clogged, the cooling water flowing out of the collector 33 can smoothly flow through the collection passage 32 to the downstream portion 27B of the drain passage 27. When the filter 43 of the collector 33 is clogged, the cooling water that has flowed through the bypass passage 34 can be prevented from flowing into the collection passage 32 from the outlet of the collection passage 32.

[0085] In the above embodiment, the upstream portion 27A of the drainage passage 27 and the collection passage 32 are arranged so that the flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 into the branch portion 35 is the same as the flow direction of the cooling water flowing from the branch portion 35 into the collection passage 32. The flow direction of the cooling water flowing from the upstream portion 27A of the drainage passage 27 into the branch portion 35 and the flow direction of the cooling water flowing from the branch portion 35 into the collection passage 32 do not have to be completely the same as each other, and may be slightly different as long as the smooth flow of cooling water from the upstream portion 27A of the drainage passage 27 to the collection passage 32 is ensured when the filter 43 of the collector 33 is not clogged.

[0086] In the above embodiment, the bypass passage 34 and the downstream portion 27B of the drain passage 27 are arranged so that the flow direction of the cooling water flowing from the bypass passage 34 to the junction 36 and the flow direction of the cooling water flowing from the junction 36 to the downstream portion 27B of the drain passage 27 are substantially the same. The flow direction of the cooling water flowing from the bypass passage 34 to the junction 36 and the flow direction of the cooling water flowing from the junction 36 to the downstream portion 27B of the drain passage 27 are not completely identical but slightly different from each other because the extension direction of the upper end (drain hole 30) of the downstream portion 27B of the drain passage 27 is slightly inclined with respect to the vertical. However, since this degree of difference ensures the smooth flow of cooling water from the bypass passage 34 to the downstream portion 27B of the drain passage 27 and the smooth flow of exhaust gas from the downstream portion 27B of the drain passage 27 to the bypass passage 34, this degree of difference can be considered to be the same. However, the extension direction of the upper end (drainage hole 30) of the downstream portion 27B of the drainage passage 27 may be vertical, and the flow direction of the cooling water flowing from the bypass passage 34 to the confluence portion 36 may be completely identical to the flow direction of the cooling water flowing from the confluence portion 36 to the downstream portion 27B of the drainage passage 27.

[0087] In the above embodiment, the upstream portion 27A of the drain passage 27 is disposed so that the flow direction of the cooling water flowing from the upstream portion 27A of the drain passage 27 into the branch portion 35 is downward and vertical; specifically, the lower end of the upstream portion 27A of the drain passage 27 extends vertically. The collection passage 32 is disposed so that the flow direction of the cooling water flowing from the branch portion 35 into the collection passage 32 is downward and vertical; specifically, the upper end of the collection passage 32 extends vertically. The bypass passage 34 is disposed so that the flow direction of the cooling water flowing from the bypass passage 34 into the junction 36 is downward and vertical; specifically, the lower end of the bypass passage 34 extends vertically. These flow directions and extension directions do not have to be completely vertical, and may be slightly inclined relative to the vertical.

[0088] Furthermore, in the above embodiment, the fine object collecting device 31 is positioned on the left side of the rear of the engine 2, but the fine object collecting device 31 may also be positioned at another position around the engine 2, such as on the right side of the rear of the engine 2.

[0089] The power source of the outboard motor 1 is not limited to an engine, but may be an electric motor. The cooling device of the present invention is not limited to outboard motors, and may also be installed in other types of marine propulsion motors, such as inboard-outboard motors or inboard motors.

[0090] Furthermore, the present invention can be modified as appropriate within the scope of the claims and the gist or concept of the invention that can be read from the entire specification, and cooling devices for marine propulsion units that involve such modifications are also included in the technical concept of the present invention. [Explanation of symbols]

[0091] 1. Outboard motor (marine propulsion unit) 2 Engine (power source) 21 Cooling device 27 Drain passage 27A Upstream section 27B downstream 32 Collection passage 33 Collector 34 Bypass Passage 35 Branch 36 Junction

Claims

1. A cooling device for a marine propulsion device that is provided to a marine propulsion device, takes in water outside the marine propulsion device into the marine propulsion device, flows the taken-in water around or inside a power source of the marine propulsion device as cooling water to cool the power source, and discharges the cooling water after flowing around or inside the power source to the outside of the marine propulsion device, a drainage passage for discharging the cooling water after flowing around or inside the power source to the outside of the marine propulsion device; a collection passage interposed between the upstream portion and the downstream portion of the drainage passage and connecting the upstream portion and the downstream portion of the drainage passage; a collector provided in the collection passage and configured to collect fine particles contained in the cooling water flowing through the collection passage from the upstream portion of the drain passage toward the downstream portion of the drain passage; a bypass passage connected in parallel with the collection passage between the upstream and downstream portions of the drainage passage; a branching portion where an upstream portion of the drainage passage branches into the collection passage and the bypass passage; a junction portion where the collection passage and the bypass passage join at a downstream portion of the drainage passage, the upstream portion of the drainage passage, the collection passage, and the bypass passage are arranged so that the difference between the flow direction of the cooling water flowing from the upstream portion of the drainage passage into the branch portion and the flow direction of the cooling water flowing from the branch portion into the collection passage is smaller than the difference between the flow direction of the cooling water flowing from the upstream portion of the drainage passage into the branch portion and the flow direction of the cooling water flowing from the branch portion into the bypass passage, the downstream portion of the drainage passage, the collection passage, and the bypass passage are arranged so that a difference between a flow direction of the cooling water flowing from the bypass passage to the junction and a flow direction of the cooling water flowing from the junction to the downstream portion of the drainage passage is smaller than a difference between a flow direction of the cooling water flowing from the collection passage to the junction and a flow direction of the cooling water flowing from the junction to the downstream portion of the drainage passage, The upstream portion of the drain passage has a curved bend, a downstream end of the bent portion is connected to an inlet portion of the branch portion; The cooling device for a marine propulsion unit, wherein the bypass passage branches off on a side facing an outer surface of a radially inner wall of the bent portion.

2. A cooling device for a marine propulsion unit that is provided in a marine propulsion unit, takes in water outside the marine propulsion unit into the marine propulsion unit, cools the power source by causing the taken-in water to flow around or inside the power source of the marine propulsion unit as cooling water, and discharges the cooling water after flowing around or inside the power source outside the marine propulsion unit, a drainage passage for discharging the cooling water after flowing around or inside the power source to the outside of the marine propulsion device; a collection passage interposed between the upstream portion and the downstream portion of the drainage passage and connecting the upstream portion and the downstream portion of the drainage passage; a collector provided in the collection passage and configured to collect fine particles contained in the cooling water flowing through the collection passage from the upstream portion of the drain passage toward the downstream portion of the drain passage; a bypass passage connected in parallel with the collection passage between the upstream and downstream portions of the drainage passage; a branching portion where an upstream portion of the drainage passage branches into the collection passage and the bypass passage; a junction portion where the collection passage and the bypass passage join at a downstream portion of the drainage passage, the upstream portion of the drainage passage, the collection passage, and the bypass passage are arranged so that the difference between the flow direction of the cooling water flowing from the upstream portion of the drainage passage into the branch portion and the flow direction of the cooling water flowing from the branch portion into the collection passage is smaller than the difference between the flow direction of the cooling water flowing from the upstream portion of the drainage passage into the branch portion and the flow direction of the cooling water flowing from the branch portion into the bypass passage, the downstream portion of the drainage passage, the collection passage, and the bypass passage are arranged so that a difference between a flow direction of the cooling water flowing from the bypass passage to the junction and a flow direction of the cooling water flowing from the junction to the downstream portion of the drainage passage is smaller than a difference between a flow direction of the cooling water flowing from the collection passage to the junction and a flow direction of the cooling water flowing from the junction to the downstream portion of the drainage passage, The upstream portion of the drainage passage has a curved portion that is curved in an arc shape, a downstream end of the bent portion is connected to an inlet portion of the branch portion; 10. A cooling device for a marine propulsion unit, wherein the bypass passage extends from the branching portion toward a side where a center of the arc of the bent portion is located.

3. the upstream portion of the drainage passage and the collection passage are arranged so that the flow direction of the cooling water flowing from the upstream portion of the drainage passage into the branch portion and the flow direction of the cooling water flowing from the branch portion into the collection passage are the same, 3. A cooling device for a marine propulsion unit as described in claim 1, wherein the upstream portion of the drainage passage and the bypass passage are arranged so that the flow direction of the cooling water flowing from the upstream portion of the drainage passage into the branch portion differs from the flow direction of the cooling water flowing from the branch portion into the bypass passage.

4. the collecting passage and the downstream portion of the drainage passage are arranged such that the flow direction of the cooling water flowing from the collecting passage into the junction portion is different from the flow direction of the cooling water flowing from the junction portion into the downstream portion of the drainage passage, 4. A cooling device for a marine propulsion unit as described in any one of claims 1 to 3, characterized in that the bypass passage and the downstream portion of the drainage passage are arranged so that the flow direction of the cooling water flowing from the bypass passage into the junction and the flow direction of the cooling water flowing from the junction into the downstream portion of the drainage passage are the same.

5. the upstream portion of the drainage passage is arranged so that the flow direction of the cooling water flowing from the upstream portion of the drainage passage into the branch portion is downward and vertical; the collection passage is arranged so that the flow direction of the cooling water flowing from the branch portion into the collection passage is downward and vertical, 5. The cooling device for a marine propulsion device according to claim 1, wherein the bypass passage is arranged so that the flow direction of the cooling water flowing from the branch portion into the bypass passage is not vertical.

6. the collection passage is disposed so that the flow direction of the cooling water flowing from the collection passage into the junction is not vertical, the bypass passage is arranged so that the flow direction of the cooling water flowing from the bypass passage into the junction is downward and vertical, A cooling device for a marine propulsion unit as described in any one of claims 1 to 5, characterized in that the downstream portion of the drainage passage is arranged so that the flow direction of the cooling water flowing from the confluence portion into the downstream portion of the drainage passage is downward and vertical.

7. 7. A cooling device for a marine propulsion unit according to claim 1, wherein the collection passage and the bypass passage intersect at the branching portion at an acute angle.

8. 8. A cooling device for a marine propulsion unit according to claim 1, wherein the collection passage and the bypass passage intersect at the junction at an acute angle.

Images