Outboard motor

Abstract

To prevent rapid cooling of parts affected by exhaust heat while suppressing an increase in the supply of cooling water. [Solution] An outboard motor is provided with an outboard motor body (12) that generates thrust by driving a propeller (18) with the driving force of an installed internal combustion engine (31), the outboard motor body (12) having a case (21) that extends vertically and whose lower part can be submerged below the water surface, a cooling water passage (51) that takes in cooling water from the outside to cool the internal combustion engine (31), and an exhaust passage (61) provided inside the case (21) that guides exhaust from the internal combustion engine (31) to the outside of the lower end of the case (21), and a cooling water supply unit (71) that branches off from the drain passage (54) of the cooling water passage (51) and supplies a portion of the cooling water from the drain passage (54) to the exhaust passage (61).

Description

Technical Field

[0001] The present invention relates to an outboard motor.

Background Art

[0002] An outboard motor includes an outboard motor body that generates propulsion by driving a propeller with the driving force of an internal combustion engine mounted thereon. The outboard motor body includes a case that extends in the vertical direction and whose lower part can be immersed below the water surface, a cooling water passage that takes in cooling water from the outside and cools the internal combustion engine, and an exhaust passage that is provided in the case and guides the exhaust from the internal combustion engine to the outside of the lower end of the case. A water-cooled outboard motor is known. Such an outboard motor has a configuration including water supply means for supplying surrounding water to the cooling water passage through a water passage and directly supplying water from the water passage to the outer surface of a heated portion that branches from the water passage and is heated by the heat of the exhaust passing through a muffler (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional configuration, since a part of the low-temperature cooling water before cooling the internal combustion engine is supplied to the heated portion outside the internal combustion engine, that cooling water is not used for cooling the internal combustion engine. As a result, the supply amount of the cooling water increases, and there is a risk that the portion heated by the heat of the exhaust is rapidly cooled. The present invention has been made in view of the above circumstances, and an object thereof is to suppress an increase in the supply amount of cooling water and prevent rapid cooling of a portion affected by the heat of the exhaust.

Means for Solving the Problems

[0005] The present invention provides a water-cooled outboard motor comprising an outboard motor body that generates thrust by driving a propeller with the driving force of an onboard internal combustion engine, the outboard motor body comprising a case that extends vertically and whose lower part can be submerged below the water surface, a cooling water passage that takes in cooling water from the outside to cool the internal combustion engine, and an exhaust passage provided inside the case that guides exhaust from the internal combustion engine to the outside of the lower end of the case, and an outboard motor comprising a cooling water supply unit that branches off from the drain passage of the cooling water passage and supplies a portion of the cooling water from the drain passage to the exhaust passage. [Effects of the Invention]

[0006] According to the present invention, it is possible to prevent rapid cooling of parts affected by the heat of exhaust gases while suppressing an increase in the supply amount of cooling water. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an outboard motor according to an embodiment of the present invention. [Figure 2] This diagram shows the engine's cooling water passages along with the surrounding configuration. [Figure 3] This is a view of the III-III section in Figure 1. [Figure 4] This diagram shows the oil case and coolant supply unit, along with the surrounding components, from the right side. [Figure 5] This is a diagram showing the VV cross-section, as shown in Figure 4. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows an outboard motor 10 according to an embodiment of the present invention. The outboard motor 10 comprises an outboard motor body 12, a mounting portion 14 for attachment to a ship, and a lower mount portion 16 that elastically supports the outboard motor body 12 relative to the mounting portion 14. In Figure 1 and the figures described later, the symbol FR indicates the forward direction of the outboard motor 10, the symbol UP indicates the upward direction of the outboard motor 10, and the symbol LH indicates the left direction of the outboard motor 10.

[0009] The outboard motor body 12 is equipped with a case (also called a casing) 21 that extends vertically and whose lower part can be submerged below the water surface. The case 21 covers the crankshaft 32 that extends downward from the internal combustion engine 31 (hereinafter referred to as "engine 31"). The case 21 is equipped with a cooling water passage 51 (Figure 2) that takes in cooling water from the outside to cool the engine 31, and an exhaust passage 61 (Figure 3) that guides the exhaust gas discharged from the engine 31 outwards at the lower end of the case 21.

[0010] The case 21 includes a mount case 22, an oil case 23 coupled to the lower end surface of the mount case 22, an upper separator 24 coupled to the lower end surface of the oil case 23, an extension case 25 coupled to the lower end surface of the upper separator 24, and a gear case 26 coupled to the lower end surface of the extension case 25.

[0011] The mounting section 14 is equipped with a swivel shaft 14a extending in the vertical direction and a tilt shaft 14b extending in the horizontal direction, and is attached to the stern of a ship. The lower end of the swivel shaft 14a is supported by the extension case 25 via the lower mount portion 16. The lower mount portion 16 includes a lower mount made of an elastic member that supports the swivel shaft 14a on the extension case 25, and a lower mount stopper that limits excessive movement of the lower mount.

[0012] The engine 31 is supported on the upper end surface of the mounting case 22 with its crankshaft 32 mounted vertically. The engine 31 is positioned higher than the water surface of the outboard motor 10 and is covered by the engine cover 33, which forms the outer cover of the outboard motor 10. The engine 31 is a V-type multi-cylinder engine in which a pair of banks 34, each containing multiple cylinders arranged vertically, are arranged in a V-shape. The engine 31 includes a crankcase 35 to which each bank 34 is connected, and a crankshaft 32 is rotatably supported in the crankcase 35.

[0013] The crankshaft 32 rotates by the driving force of the engine 31, and the rotation of the crankshaft 32 is transmitted to the propeller 18 via the power transmission mechanism 17. The power transmission mechanism 17 is covered with a gear case 26. The power transmission mechanism 17 may have a speed change mechanism.

[0014] The oil case 23 has a storage portion for storing oil for engine lubrication. Further, an exhaust passage 61 (FIG. 3) for guiding the exhaust from the engine 31 to the outside is formed in the oil case 23, the upper separator 24, and the extension case 25. The exhaust guided to the exhaust passage 61 is discharged to the outside from an exhaust port provided at the downstream end of the exhaust passage 61. The exhaust port is provided, for example, at the rear end portion of the propeller shaft 17a. A water suction port 19 for taking in the surrounding water as the cooling water of the engine 31 is provided on the side surface of the gear case 26.

[0015] FIG. 2 is a view showing the cooling water passage 51 of the engine 31 together with the peripheral configuration, and the flow of the cooling water is indicated by arrows. Reference numeral 51a in FIG. 2 indicates the cylinder head cooling water passages (including the water jackets around the cylinder heads) of the left and right banks 34 of the engine 31. Further, reference numeral 51b indicates the cylinder cooling water passages (including the water jackets around the cylinders) of each bank 34 of the engine 31.

[0016] As shown in FIG. 2, the outboard motor 10 includes a water pump 52 that sucks the surrounding water from the water suction port 19. The sucked water is pumped as cooling water to the engine 31. Since the water pump 52 is driven using the driving force of the engine 31, the supply amount of the cooling water increases in proportion to the engine speed. The cooling water passes through a pair of left and right water suction passages 53 provided inside the upper portion of the case 21, and is supplied to the cylinder head cooling water passage 51a and the cylinder cooling water passage 51b of each bank 34, respectively.

[0017] Thermostats 55 are provided at the outlet passages 51c and 51d of the cooling water passages 51a and 51b of the left and right banks 34, respectively. When the cooling water in each of the cooling water passages 51a and 51b reaches a predetermined temperature, the thermostat 55 opens, and the cooling water is supplied to a cylinder block cooling water passage 51e provided on the side surface portion of the cylinder block. Thereafter, the cooling water flows into the left and right drainage passages 54 formed in the case 21 and is discharged to the outside through a drain port provided at the downstream end of the drainage passage 54. The drain port is provided, for example, on the shaft portion (propeller shaft) 18a of the propeller 18.

[0018] During cold operation when the cooling water in each cooling water passage 51 has not reached the predetermined temperature, the thermostat 55 maintains a closed state. During this period, the cooling water is supplied to a separate drainage passage 51f branched from each of the cooling water passages 51a and 51b of the left and right banks 34. Thereafter, the cooling water flows into the left and right drainage passages 54 formed in the case 21 and is discharged to the outside through a drain port provided at the downstream end of the drainage passage 54.

[0019] The thermostat 55 provided in the cylinder head cooling water passage 51a and the thermostat 55 provided in the cylinder cooling water passage 51b are set to opening valve temperatures suitable for the cooling of their respective cooling targets (cylinder head, cylinder). In the example of FIG. 2, the cooling water passage 51 of the engine 3I is formed in a bilaterally symmetric structure. However, it does not have to be a bilaterally symmetric structure.

[0020] FIG. 3 is a view showing a cross section taken along line III-III of FIG. 1. An exhaust passage 61 extending from the oil case 23 to the upper separator 24 is formed in this cross section. In FIG. 3, for convenience of explanation, the exhaust passage 61 formed in the oil case 23 is denoted by reference numerals 61α and 61β, and the exhaust passage 61 formed in the upper separator 24 is denoted by reference numeral 61γ.

[0021] As shown in Figure 3, the oil case 23 is provided with a water jacket 23wj for cooling the exhaust passage 61α with coolant. Therefore, the temperature rise of the exhaust passage 61α is suppressed by the coolant. On the other hand, the exhaust passages 61β and 61γ downstream of the exhaust passage 61α are not provided with water jackets. As a result, the exhaust passage 61β, which is not provided with a water jacket, is particularly prone to becoming hot due to the heat effect of the exhaust.

[0022] As shown in Figure 4, the outboard motor 10 in this configuration is equipped with a cooling water supply unit 71 that supplies a portion of the cooling water to the exhaust passage 61β from outside the case 21, thereby cooling the area to be cooled, Sa, including the exhaust passage 61β and its surroundings. Figure 4 is a diagram showing the oil case 23 and the cooling water supply unit 71 together with the surrounding configuration from the right side. The arrow Y in Figure 4 indicates the direction of supply (injection direction) of the cooling water supplied by injection from the cooling water supply unit 71.

[0023] As shown in Figure 2, one cooling water supply unit 71 is provided on each side of the case 21. The left and right cooling water supply units 71 are formed in a symmetrical structure with respect to the left and right central planes of the outboard motor 10. In the following description, one of the cooling water supply units 71 will be described, and the other will not be described again.

[0024] Figure 5 shows the VV cross-section of Figure 4. As shown in Figure 5, the cooling water supply unit 71 is equipped with a cylindrical joint 72 that is inserted from the outside into the right side of the oil case 23. The joint 72 integrally comprises a base end 72k that is inserted into the oil case 23 and a tip end 72s that is exposed to the outside of the oil case 23. The joint 72 is fixed to the oil case 23 by a method such as press-fitting, but it may also be fixed by a method other than press-fitting. The joint 72 may also be called a nozzle.

[0025] The base end portion 72k is formed as a cylindrical body extending in a straight line and is inserted diagonally into the oil case 23 toward the inside and upward. The oil case 23 has a through hole 23h (a through hole 23h that extends linearly toward the inside and upward) that extends in the same direction as the base end portion 72k of the joint 72. As a result, the joint 72 communicates with the drainage passage 54 inside the oil case 23 through the through hole 23h, and a portion of the cooling water W (Figure 5) flowing downward through the drainage passage 54 flows into the joint 72.

[0026] More specifically, the oil case 23 is provided with a projection 23t that protrudes inward toward the drainage passage 54, and a through hole 23h is formed so as to communicate with the inner and upper corner of this projection 23t. As a result, the through hole 23h opens directly upward, allowing cooling water falling from above to below to flow smoothly into the through hole 23h.

[0027] The tip portion 72s of the joint 72 is formed as a cylindrical body that extends outward and downward from the oil case 23, and then bends inward and downward from the left and right, as seen in the rear view of the outboard motor 1 shown in Figure 5. Also, as seen in the side view shown in Figure 4, the tip portion 72s is formed in a shape that bends forward and downward from the oil case 23. As a result, the cooling water that flows into the joint 72 is sprayed forward and downward against the outer surface of the case 21 by the tip 72s of the joint 72.

[0028] In this configuration, by setting the main injection direction to the direction indicated by arrow Y in Figure 4, cooling water is supplied to the boundary between the oil case 23 and the upper separator 24, and to the area outside the exhaust passage 61β. This cooling water spreads in the front-rear direction and flows downward along the case 21 due to gravity, so that the cooling target area Sa shown in Figure 4 can be effectively cooled.

[0029] The cooling target region Sa is the region below the water jacket 23wj shown in Figure 3, and includes the exhaust passages 61β and 61γ, which are susceptible to the heat effects of the exhaust. This allows the entire region, which is prone to becoming hot due to the heat effects of the exhaust, to be cooled with cooling water. Furthermore, since the amount of coolant supplied from joint 72 increases in proportion to the engine speed, the amount of coolant supplied increases as the engine speed increases, effectively suppressing the temperature rise in the area Sa that is being cooled.

[0030] Furthermore, the cooling target region Sa, which is cooled by the cooling water, includes the region of the lower mount portion 16, as shown in Figure 4. In other words, the cooling water supplied from the cooling water supply unit 71 flows downward along the outer surface of the case 21, thereby cooling the region of the lower mount portion 16 from the outside. This effectively suppresses the temperature rise of the lower mount portion 16 due to the heat effect of the exhaust.

[0031] Here, as shown in Figure 1, the engine cover 33 is formed as a large cover that extends downward from the engine 31, and covers the case 21 from the outside, at least up to the extension case 25. Therefore, the coolant supply unit 71 is located inside the engine cover 33 and is not visible from the outside, which is advantageous for improving the appearance.

[0032] As described above, the outboard motor 10 of this embodiment includes an outboard motor body 12 that generates thrust by driving a propeller 18 with the driving force of an onboard engine 31. The outboard motor body 12 is configured to be water-cooled and includes a case 21 that extends vertically and whose lower part can be submerged below the water surface, a cooling water passage 51 that takes in cooling water from the outside to cool the engine 31, and an exhaust passage 61 provided inside the case 21 that guides the exhaust from the engine 31 to the outside of the lower end of the case 21. It also includes a cooling water supply unit 71 that branches off from the drain passage 54 of the cooling water passage 51 and supplies a portion of the cooling water from the drain passage 54 to the exhaust passage 61.

[0033] With this configuration, the coolant used to cool the engine 31 before being discharged to the outside is used to cool the exhaust passage 61 and its surroundings. This allows for efficient cooling of the engine 31, and eliminates the need to increase the coolant supply for cooling the exhaust passage 61 and its surroundings. Furthermore, because the coolant used to cool the engine 31 is used to cool the exhaust passage 61 and its surroundings, rapid cooling of parts affected by the heat of the exhaust can be prevented. Therefore, it is possible to prevent rapid cooling of parts affected by the heat of the exhaust while suppressing an increase in the coolant supply.

[0034] Since a thermostat 55 is located in the cooling water passage 51, the thermostat 55 can prevent the engine 31 from being overcooled when cold. Furthermore, the thermostat 55 may be configured to block the cooling water passage 51 when the engine is cold. This configuration prevents the supply of cooling water from the cooling water supply unit 71 when the engine is cold, thereby further preventing excessive cooling of parts affected by the heat of the exhaust.

[0035] Furthermore, the thermostat 55 may be provided in both the cylinder head cooling water passage 51a and the cylinder cooling water passage 51b, with different opening temperatures for each, and each thermostat 55 may be configured to block the respective cooling water passages 51a and 51b when cold. With this configuration, after warming up, the cooling water can be supplied from the cooling water supply unit 71 while gradually increasing the water pressure.

[0036] The system has a mounting section 14 that is attached to the hull and a lower mount section 16 that elastically supports the outboard motor body 12 relative to the mounting section 14. Cooling water from the cooling water supply section 71 is supplied to the area above the lower mount section 16 and then flows through the area corresponding to the lower mount section 16. This makes it possible to suppress the temperature rise of the lower mount section 16 and its surroundings.

[0037] The cooling water supply unit 71 branches off from the drainage passage 54 of the cooling water passage 51 and supplies a portion of the cooling water from the drainage passage 54 to the cooling target area Sa shown in Figure 4 from outside the case 21. This allows the part affected by the heat of the exhaust to be cooled from outside the case 21, thereby suppressing the heat impact on the case 21 and its surroundings. This cooling target area Sa is an example of a predetermined area affected by the heat of the exhaust in this disclosure and may be changed as appropriate.

[0038] The cooling water supply unit 71 has a joint 72 that penetrates the case 21 and sprays a portion of the cooling water from the drainage passage 54 toward the outer surface of the case 21. This improves the degree of freedom in adjusting the range and direction of the cooling water supply, making it possible to cool effectively with a small amount of cooling water.

[0039] Furthermore, since the joint 72 sprays cooling water forward and downward, it can suppress the entry of foreign matter (such as sand or shell fragments) into the joint 72 compared to when the cooling water is sprayed upward.

[0040] Furthermore, the engine 31 is a V-type engine, and the joints 72 are provided on both the left and right sides of the outboard motor. This allows the left and right cooling target areas Sa, which are affected by the heat of the left and right exhaust passages 61, to be cooled, making it possible to cool both sides equally. Engine 31 is merely an example of an internal combustion engine according to this disclosure and is not limited to a V-type engine; a wide range of known internal combustion engines can be applied.

[0041] Furthermore, the joint 72 is located inside the engine cover 33, which covers at least a portion of the outboard motor 10 from the outside. As a result, the joint 72 is not visible from the outside, which is advantageous for improving the appearance.

[0042] [Other embodiments] The above embodiments represent only one aspect of the present invention and can be modified and applied as needed without departing from the spirit of the invention.

[0043] In the above embodiment, the case in which the present invention is applied to the outboard motor 10 shown in Figure 1, etc., was described, but the structure and shape of each part may be changed as appropriate. For example, the present invention is not limited to the outboard motor 10 equipped with a V-type multi-cylinder engine, but can be applied to outboard motors equipped with other types of engines.

[0044] Furthermore, the cooling water supply unit 71 may also be modified as appropriate, within the range that allows cooling water to be supplied from the outside to the area of ​​the exhaust passage 61 that is affected by heat. For example, the position, shape, and number of joints 72 may be changed. In addition, although a configuration in which cooling water is injected by joints 72 has been given as an example, the system is not limited to this, and other cooling water supply structures may be adopted.

[0045] [Configurations supported by the above embodiment] The above embodiment supports the following configuration.

[0046] (Configuration 1) An outboard motor comprising an outboard motor body that generates thrust by driving a propeller with the driving force of an installed internal combustion engine, wherein the outboard motor body comprises a case that extends vertically and whose lower part can be submerged below the water surface, a cooling water passage that takes in cooling water from the outside to cool the internal combustion engine, and an exhaust passage provided inside the case that guides exhaust from the internal combustion engine to the outside of the lower end of the case, wherein the outboard motor comprises a cooling water supply unit that branches off from the drain passage of the cooling water passage and supplies a portion of the cooling water from the drain passage to the exhaust passage. This configuration allows for suppressing an increase in the supply of cooling water while preventing rapid cooling of parts affected by the heat of the exhaust.

[0047] (Configuration 2) The outboard motor according to claim 1, wherein a thermostat is provided in the cooling water passage. This configuration prevents the internal combustion engine from being overcooled when cold. By configuring the thermostat to block the coolant passage when cold, coolant can not be supplied from the coolant supply unit when cold, further preventing overcooling of parts affected by the heat of the exhaust.

[0048] (Configuration 3) An outboard motor according to Configuration 1 or 2, having a mounting portion attached to the hull and a lower mount portion that elastically supports the outboard motor body with respect to the mounting portion, wherein the cooling water from the cooling water supply portion is supplied to the region above the lower mount portion and then flows through the region corresponding to the lower mount portion. This configuration makes it possible to suppress the temperature rise in the lower mount section and its surrounding area.

[0049] (Configuration 4) The outboard motor according to any one of Configurations 1 to 3, wherein the cooling water supply unit branches off from the drainage passage of the cooling water passage and supplies a portion of the cooling water from the drainage passage to a predetermined area affected by the heat of the exhaust passage from outside the case. This configuration allows the parts affected by the exhaust heat to be cooled from outside the case, thereby suppressing the heat impact on the case and its surroundings.

[0050] (Configuration 5) The outboard motor according to any one of Configurations 1 to 4, wherein the cooling water supply unit has a joint that penetrates the case and sprays a portion of the cooling water from the drainage passage toward the outer surface of the case. This configuration improves the flexibility of adjusting the range and direction of the cooling water supply, making it possible to effectively cool with a small amount of cooling water.

[0051] (Configuration 6) The outboard motor according to Configuration 5, wherein the joint sprays the cooling water forward and downward. This configuration makes it possible to prevent foreign objects from entering the joint from the outside.

[0052] (Configuration 7) The outboard motor according to any one of Configurations 1 to 6, wherein the internal combustion engine is a V-type engine, and the joints are provided on the left and right sides of the outboard motor. This configuration allows for even cooling on both sides.

[0053] (Configuration 8) The outboard motor according to any one of Configurations 5 to 7, wherein the joint is provided within a cover that covers at least a part of the outboard motor from the outside. With this configuration, the joints are not visible from the outside, which is advantageous for improving the appearance. [Explanation of Symbols]

[0054] 10… Outboard motor 12 Outboard motor body 14 Mounting part 16 Lower Mount Section 18 Propellers 21 cases 31. Internal combustion engine 33 Engine cover 51 Cooling water passage 54 Drain passage 55 Thermostat 61 Exhaust passage 71 Cooling water supply section 72 joints

Claims

1. An outboard motor (outboard motor) is provided with an outboard motor body (12) that generates thrust by driving a propeller (18) with the driving force of an onboard internal combustion engine (31), the outboard motor body (12) comprises a case (21) that extends vertically and whose lower part can be submerged below the water surface, a cooling water passage (51) that takes in cooling water from the outside to cool the internal combustion engine (31), and an exhaust passage (61) provided inside the case (21) that guides exhaust from the internal combustion engine (31) to the outside of the lower end of the case (21), The cooling water supply unit (71) branches off from the drainage passage (54) of the cooling water passage (51) and supplies a portion of the cooling water from the drainage passage (54) to the exhaust passage (61). Outboard motor.

2. A thermostat (55) is placed in the cooling water passage (51). The outboard motor according to claim 1.

3. It has a mounting portion (14) that is attached to the hull and a lower mount portion (16) that elastically supports the outboard motor body (12) with respect to the mounting portion (14), The cooling water from the cooling water supply unit (71) is supplied to the area above the lower mount portion (16) and then flows through the area corresponding to the lower mount portion (16). The outboard motor according to claim 2.

4. The cooling water supply unit (71) branches off from the drainage passage (54) of the cooling water passage (51) and supplies a portion of the cooling water from the drainage passage (54) from outside the case (21) to a predetermined area affected by the heat of the exhaust passage (61). The outboard motor according to claim 1.

5. The cooling water supply unit (71) has a joint (72) that penetrates the case (21) and sprays a portion of the cooling water from the drainage passage (54) toward the outer surface of the case (21). The outboard motor according to claim 1.

6. The joint (72) sprays the cooling water forward and downward. The outboard motor according to claim 5.

7. The internal combustion engine (31) is a V-type engine, and the joint (72) is provided on the left and right sides of the outboard motor. The outboard motor according to claim 5.

8. The joint (72) is provided within a cover (33) that covers at least a portion of the outboard motor from the outside. The outboard motor according to claim 5.

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