Engine cooling device

Abstract

To improve sealing performance by using a simple and inexpensive configuration when a water pump is installed in a crank case having a divided structure.SOLUTION: A cooling device for an engine (10) is installed in a crank case (11). The cooling device for the engine includes: a water pump (41) discharging cooling water toward the crank case; and a gasket used for installation of a pump body of the water pump. The crank case has a divided structure including a first case (21) and a second case (22). The gasket is interposed between the first case and the pump body and between the second case and the pump body.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an engine cooling device.

Background Art

[0002] Generally, an engine is provided with a cooling device that circulates cooling water between a water jacket in the cylinder and a radiator outside the cylinder. As an engine cooling device, one in which a water pump is installed on the side surface of the crankcase is known (see, for example, Patent Document 1). The water pump described in Patent Document 1 is positioned in front of the crankshaft and is screwed to the side surface of the crankcase via a sealing material by a plurality of bolts. By installing the water pump close to the radiator, the cooling components of the cooling device are compactly laid out on the front side of the crankshaft.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The crankcase described in Patent Document 1 has an upper and lower split structure composed of an upper case and a lower case. The upper part of the water pump is installed on the side surface of the upper case, and the lower part of the water pump is installed on the side surface of the lower case. Therefore, when an O-ring is used as a sealing material for installing the water pump, there is a risk that the O-ring may be damaged by the edge of the mating surface of the upper case and the lower case, resulting in a decrease in sealing performance.

[0005] The present invention has been made in consideration of the above points, and aims to provide an engine cooling device that can improve sealing performance with a simple and inexpensive configuration when installing a water pump in a crankcase with a split structure. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided an engine cooling device that is installed in a crankcase, the engine cooling device including a water pump that discharges cooling water toward the crankcase, a gasket used to install a pump body of the water pump, The O-ring used for the installation of the discharge part of the water pump, The crankcase has a split structure including a first case and a second case, and between the first case and the pump body, and, The gasket is interposed between the second case and the pump body. , the O-ring is interposed between the first case and the discharge part, the gasket is held on the installation surface of the pump body, and the installation surface of the pump body is recessed from the contact surface of the O-ring with respect to the first case This solves the above problem. Effect of the Invention

[0007] According to an engine cooling device of one aspect of the present invention, the crankcase has a divided structure including a first and second case, and the pump body of the water pump is installed in the first and second cases via a gasket. Since a highly durable gasket is used as a sealing material to install the pump body, the gasket will not be damaged by the edges of the mating surfaces of the first and second cases. Therefore, even in a structure in which the water pump is installed across the first and second cases, it is possible to improve sealing performance with a simple and inexpensive configuration. [Brief description of the drawings]

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0009] The cooling device of an engine according to one aspect of the present invention is installed in a crankcase. In this engine cooling device, cooling water is discharged from a water pump toward the crankcase, and a gasket is used for installing the pump body of the water pump. The crankcase has a split structure including a first case and a second case, and gaskets are interposed between the first case and the pump body and between the second case and the pump body. Since a gasket with high durability is used as a sealing material for installing the pump body, the gasket is not damaged by the edges of the mating surfaces of the first and second cases. Therefore, even in a structure where the water pump is installed across the first and second cases, the sealing performance can be improved with a simple and inexpensive configuration.

Example

[0010] Hereinafter, this embodiment will be described in detail with reference to the accompanying drawings. FIG. 1 is a left side view of the engine of this embodiment. FIG. 2 is a front view of the engine of this embodiment. In the following figures, arrow FR indicates the front, arrow RE indicates the rear, arrow L indicates the left, and arrow R indicates the right, respectively.

[0011] As shown in FIGS. 1 and 2, the engine 10 includes a crankcase 11 that houses a crankshaft 38. On the upper part of the crankcase 11, a cylinder assembly in which a cylinder 12, a cylinder head 13, and a cylinder head cover 14 are stacked is attached. On the lower part of the crankcase 11, an oil pan 15 in which oil for lubrication and cooling is stored is attached. On the front part of the crankcase 11, an oil filter 16 for removing foreign matter from the oil and an oil cooler 17 for cooling the oil are attached. In front of the cylinder 12, a radiator 31 for dissipating the heat of the cooling water is provided.

[0012] A magnet cover 18 that covers the magnet chamber inside the case is attached to the left side surface of the crankcase 11, and a clutch cover 19 that covers the clutch chamber inside the case is attached to the right side surface of the crankcase 11. A magnet device (not shown) connected to the crankshaft 38 is housed in the magnet chamber, and a clutch device (not shown) for transmitting and interrupting the power from the crankshaft 38 is housed in the clutch chamber. Also, a water pump 41 for discharging the cooling water toward the crankcase 11 is attached to the right side surface of the crankcase 11.

[0013] The crankcase 11 has an upper and lower split structure (split structure) including an upper case (first case) 21 and a lower case (second case) 22. The crankshaft 38 and the balance shaft 39 are pivotally supported on the mating surface 23 of the upper case 21 and the lower case 22. The balance shaft 39 is positioned inside the water pump 41 installed in front of the crankshaft 38. The balance shaft 39 is fitted to an impeller 55 housed inside the water pump 41, and the water pump 41 is driven by the impeller 55 with the balance shaft 39 as the rotation axis.

[0014] The lower part of the water pump 41 is the pump body 71 that houses the impeller 55, and the upper part of the water pump 41 is the discharge part 76 where the discharge port 57 is formed. Since the pump body 71 is installed across the upper case 21 and the lower case 22, it is desirable to use a gasket with high durability as a sealing material for the installation of the pump body 71 so that the sealing material is not damaged by the edge of the mating surface 23 of the upper case 21 and the lower case 22. Further, the discharge part 76 is required to have a higher sealing property than the pump body 71, and it is desirable to use an O-ring as a sealing material for the installation of the discharge part 76.

[0015] Hereinafter, with reference to FIGS. 3 to 7, the engine cooling device will be described. FIG. 3 is a schematic diagram of the engine cooling device of the present embodiment. FIG. 4 is a perspective view of the water pump of the present embodiment. FIG. 5 is an outer side view of the water pump of the present embodiment. FIG. 6 is an inner side view of the water pump of the present embodiment. FIG. 7 is a side view of the front side portion of the crankcase of the present embodiment. Note that FIGS. 5 and 6 show a state in which the thermostat cover is removed from the water pump.

[0016] As shown in FIG. 3, the engine 10 is provided with a cooling device 30 that circulates cooling water between the engine 10 and the radiator 31. The radiator 31 has a radiator core 32 that exchanges heat by a large number of thin tubes or heat dissipation fins, an inflow tank 33 that allows cooling water to flow in from one side of the radiator core 32, and an outflow tank 34 that allows cooling water to flow out from the other side of the radiator core 32. A water injection port for cooling water is formed on the upper surface of the outflow tank 34, and a radiator cap 35 is attached to the water injection port. A radiator fan 36 that guides outside air toward the radiator core 32 when the vehicle stops or the like is provided on the back side of the radiator core 32.

[0017] The discharge port 57 of the water pump 41 communicates with the cooling flow path 49 in the crankcase 11, and the cooling flow path 49 in the crankcase 11 communicates with the water jackets of the cylinder 12 and the cylinder head 13. A connector 42 for a pipe joint projects from the rear part of the cylinder 12, and an inlet pipe 43 for sending cooling water to the inflow tank 33 of the radiator 31 and a bypass pipe 44 for bypassing the radiator 31 and returning the cooling water to the water pump 41 are connected to the connector 42. An outlet pipe 45 for returning the cooling water that has passed through the radiator core 32 to the water pump 41 is connected to the outflow tank 34 of the radiator 31.

[0018] An inlet control type thermostat 46 for controlling the flow of the cooling water from the outlet pipe 45 according to the cooling water temperature is attached to the water pump 41. When the cooling water temperature is lower than a predetermined temperature, the thermostat 46 closes the valve, and the flow of the cooling water from the engine 10 to the radiator 31 is blocked at the outlet of the outlet pipe 45 on the downstream side of the radiator 31. The cooling water is returned from the engine 10 to the water pump 41 through the bypass pipe 44. When the cooling water temperature rises above the predetermined temperature, the thermostat 46 opens the valve, and the cooling water also flows from the engine 10 to the radiator 31, and the engine 10 is effectively cooled by the cooling water radiated by the radiator 31.

[0019] In this way, the cooling device 30 of the engine 10 is provided with a thermostat 46 for sending the cooling water to the radiator 31 according to the cooling water temperature. The flow of the cooling water toward the radiator 31 and the flow of the cooling water bypassing the radiator 31 are controlled by the thermostat 46. Further, an inlet pipe 47 for sending the cooling water to the oil cooler 17 is connected to the water pump 41, and an outlet pipe 48 for returning the cooling water to the water pump 41 is connected to the oil cooler 17. By driving the water pump 41, the cooling water is sent to the oil cooler 17, and the oil in the oil cooler 17 is cooled by the cooling water.

[0020] As shown in FIGS. 4 to 6, the water pump 41 has a pump case 51 with one side open and a pump cover 52 that covers the opening of the pump case 51. Clamping portions 53a - 53f are formed at the outer edge portions of the pump case 51 and the pump cover 52. In the clamping portions 53a - 53e, the pump cover 52 and the pump case 51 are screwed to the crank case 11 (see FIG. 7), and in the clamping portion 53f, the pump cover 52 is screwed to the pump case 51. The pump case 51 and the pump cover 52 form a circular pump chamber 54 in which the impeller 55 is accommodated and a discharge flow path 56 that extends tangentially from the pump chamber 54.

[0021] The impeller 55 is a centrifugal impeller that pumps cooling water using centrifugal force, and the rotation of the impeller 55 sends the cooling water into the discharge flow path 56. A discharge port 57 for sending cooling water into the crank case 11 is formed in the pump case 51 from the tip side of the discharge flow path 56. A pair of nipples 58, 59 for pipe joints project from the lower part of the pump case 51. An inlet pipe 47 leading from the water pump 41 to the oil cooler 17 (see FIG. 1) is connected to one nipple 58, and an outlet pipe 48 returning from the oil cooler 17 to the water pump 41 is connected to the other nipple 59.

[0022] A part of the pump cover 52 protrudes above the pump case 51, and a thermostat housing portion 61 is formed in front of the discharge port 57. The thermostat housing portion 61 is formed in a bottomed cylindrical shape, and a thermostat 46 (see FIG. 3) is mounted on the opening edge of the thermostat housing portion 61. A nipple 62 for a pipe joint projects from the side wall of the thermostat housing portion 61. A bypass pipe 44 that bypasses the radiator 31 and returns to the water pump 41 is connected to the nipple 62. The accommodation chamber of the thermostat 46 is connected to the pump chamber 54 through the suction flow path 63, and the cooling water from the bypass pipe 44 is returned to the pump chamber 54.

[0023] In the thermostat housing portion 61, a thermostat cover 64 is attached so as to cover the housing chamber of the thermostat 46. A pipe 65 for a pipe joint is formed in the thermostat cover 64. An outlet pipe 45 that returns from the radiator 31 (see FIG. 3) to the water pump 41 is connected to the pipe 65. The thermostat 46 is attached in a direction to stop the cooling water from the outlet pipe 45. The flow rate of the cooling water flowing from the outlet pipe 45 into the suction passage 63 through the housing chamber of the thermostat housing portion 61 is adjusted according to the opening degree of the thermostat 46.

[0024] Wax is sealed inside the thermostat 46, and the thermostat 46 opens when the wax expands according to the cooling water temperature. In a state where the cooling water temperature is low and the wax contracts, the thermostat 46 closes, and cooling water flows from the bypass pipe 44 into the thermostat housing portion 61. When the cooling water temperature rises and the wax expands, the thermostat 46 opens, and cooling water flows from the outlet pipe 45 into the thermostat housing portion 61. The flow rate of the cooling water from the bypass pipe 44 into the thermostat housing portion 61 decreases by the increased amount of the flow rate of the cooling water from the outlet pipe 45 into the thermostat housing portion 61.

[0025] As shown in FIGS. 4 and 6, the bottom surface of the pump case 51 of the water pump 41 is the installation surface with respect to the crank case 11 (see FIG. 7). The lower part of the water pump 41 is a pump body 71 in which an impeller 55 is housed. The pump body 71 is formed in a substantially rectangular shape with four tightening portions 53a - 53d as vertices in a side view. A boss 73 protrudes from the installation surface 72 of the pump body 71, and the tip of the impeller shaft 74 protrudes from the protruding end surface of the boss 73. Further, a convex portion 75 for holding a gasket 81 protrudes from the installation surface 72 of the pump body 71, and the gasket 81 is held on the installation surface 72 of the pump body 71 by the convex portion 75.

[0026] The gasket 81 is a so-called metal gasket and has an annular portion 82 formed to surround the impeller shaft 74 and a hooking portion 83 that catches on the convex portion 75 inside the annular portion 82. The annular portion 82 is formed in a rectangular frame shape along the peripheral edge of the pump body 71. Four bolts 69 protruding from the tightening portions 53a - 53d are inserted into the insertion holes at the four corners of the annular portion 82, and the gasket 81 is positioned with respect to the pump body 71. The tightening portions 53a - 53d are tightened to the crankcase 11 via the four corners of the gasket 81 by the four bolts 69. Thus, the gasket 81 is used for the installation of the pump body 71.

[0027] A plurality of arm portions 84 extend from the hooking portion 83 to the annular portion 82, and the hooking portion 83 is supported inside the annular portion 82 via the plurality of arm portions 84. An opening into which the convex portion 75 enters is formed in the hooking portion 83, and three claw portions protrude from the opening edge toward the convex portion 75. The gasket 81 is held on the installation surface 72 of the pump body 71 when the claw portions of the hooking portion 83 catch on the convex portion 75. Since the gasket 81 is held inside the annular portion 82 and on the pump body 71, the holding position of the gasket 81 is hidden and does not affect the appearance. The falling of the gasket 81 during assembly is suppressed by the hooking structure, and the assemblability of the gasket 81 can be improved.

[0028] The upper part of the water pump 41 is a discharge portion 76 where a discharge port 57 is formed. An annular groove is formed around the discharge port 57 on the installation surface 77 of the discharge portion 76, and an O - ring 87 is held on the installation surface 77 of the discharge portion 76 by the annular groove. A tightening portion 53e is formed at one location of the discharge portion 76, and the tightening portion 53e is tightened to the crankcase 11 by one bolt 69. Thus, the O - ring 87 is used for the installation of the discharge portion 76. The gasket 81 is used for the installation of the pump body 71 where a relatively low sealing pressure is required, and the O - ring 87 is used for the installation of the discharge portion 76 where a relatively high sealing pressure is required.

[0029] In the water pump 41 (pump case 51), a recess 78 is formed between the pump body 71 and the discharge part 76. Due to the recess 78, the water pump 41 is hollowed out and its weight is reduced. The flexibility in the vicinity of the recess 78 is increased, the surface pressure in the vicinity of the tightening parts 53a - 53e is increased, and the sealing performance is improved. The tightening part 53e of the discharge part 76 is formed on the side opposite to the recess 78 with the O-ring 87 sandwiched therebetween. By separating the tightening parts 53a - 53d of the pump body 71 and the tightening part 53e of the discharge part 76 with the recess 78 in between, it becomes difficult for the tightening state of the tightening part 53e of the discharge part 76 to be affected by the tightening state of the tightening parts 53a - 53d of the pump body 71, and the sealing performance of the gasket 81 is improved.

[0030] Also, the installation surface 72 of the pump body 71 is recessed more than the installation surface 77 of the discharge part 76, and a step is formed between the installation surface 72 of the pump body 71 and the installation surface 77 of the discharge part 76. The gasket 81 on the installation surface 72 of the pump body 71 protrudes from the installation surface 77 of the discharge part 76 in a non-compressed state, and is configured such that the gasket 81 contacts the crankcase 11 before the O-ring 87 when the water pump 41 is installed. Although details will be described later, by appropriately protruding the gasket 81 from the installation surface 77 of the discharge part 76, the gap between the O-ring 87 and the crankcase 11 is eliminated, and the surface pressure of the gasket 81 is sufficiently ensured to improve the sealing performance of the water pump 41.

[0031] As shown in FIGS. 6 and 7, a rectangular frame-shaped gasket contact surface 24 that contacts the gasket 81 protrudes from the right side surface of the crankcase 11. Thread holes are formed at the tightening locations 25a - 25d at the four corners of the gasket contact surface 24 corresponding to the tightening parts 53a - 53d of the water pump 41. A through hole 26 connected to the balancer chamber is formed inside the gasket contact surface 24. As described above, the crankcase 11 has an upper and lower split structure, and the upper half of the gasket contact surface 24 and the through hole 26 are formed in the upper case 21, and the lower half of the gasket contact surface 24 and the through hole 26 are formed in the lower case 22.

[0032] Above the gasket contact surface 24, a circular O-ring contact surface 27 that contacts the O-ring 87 protrudes from the right side surface of the upper case 21. An inlet 28 of the cooling flow path 49 (see FIG. 3) in the crank case 11 is formed in the O-ring contact surface 27. Since the O-ring contact surface 27 is close to the tightening portion 25d of the gasket contact surface 24, a tightening portion 25e of the O-ring contact surface 27 is formed on the opposite side of the tightening portion 25d across the inlet 28 so that the tightening of the O-ring contact surface 27 hardly affects the tightening portion 25d. A screw hole is formed in the tightening portion 25e of the O-ring contact surface 27 corresponding to the tightening portion 53e of the water pump 41.

[0033] When installing the water pump 41, the boss 73 of the pump body 71 is inserted into the through hole 26 of the crank case 11. The pump body 71 is pressed against the gasket contact surface 24 via the gasket 81, and the discharge portion 76 is pressed against the O-ring contact surface 27 via the O-ring 87. The tightening portions 53a - 53d of the pump body 71 are screwed to the tightening portions 25a - 25d of the gasket contact surface 24, and the tightening portion 53e of the discharge portion 76 is screwed to the tightening portion 25e of the O-ring contact surface 27. In this way, the pump body 71 is installed across the upper case 21 and the lower case 22, and the discharge portion 76 is installed in the upper case 21.

[0034] A gasket 81 is interposed between the upper case 21 and the pump body 71, and between the lower case 22 and the pump body 71. Since the durability of the gasket 81 is high, the gasket 81 is not damaged by the edge of the mating surface 23 of the upper case 21 and the lower case 22. The installation surface 72 of the pump body 71 and the gasket contact surface 24 of the upper case 21 and the lower case 22 are sealed by the gasket 81 with appropriate pressure. An O-ring 87 is interposed between the upper case 21 and the discharge portion 76. The installation surface 72 of the discharge portion 76 and the O-ring contact surface 27 of the upper case 21 are sealed by the O-ring 87 with appropriate pressure.

[0035] Referring to FIGS. 8 to 10, the sealing state of the water pump will be described. FIG. 8 is a diagram showing the sealing state of a comparative example and the surface pressure distribution of the gasket contact surface. FIG. 9 is a diagram showing the sealing state of another comparative example and the surface pressure distribution of the gasket contact surface. FIG. 10 is a diagram showing the sealing state of this embodiment and the surface pressure distribution of the gasket contact surface.

[0036] As shown in FIG. 8(A), in the water pump 90 of the comparative example, the installation surface 92 of the pump body 91 and the installation surface 94 of the discharge part 93 are formed on the same surface. The gasket contact surface 24 and the O-ring contact surface 27 of the crankcase 11 are formed on the same surface. A gasket 95 is held on the installation surface 92 of the pump body 91, and an O-ring 96 is held in the annular groove of the installation surface 94 of the discharge part 93. When the bolt is tightened, the gasket 95 is crushed between the installation surface 92 of the pump body 91 and the gasket contact surface 24. If the crushing allowance of the gasket 95 is small, a gap is generated between the O-ring 96 and the O-ring contact surface 27, and the sealing performance of the O-ring 96 deteriorates.

[0037] In this case, by using a gasket 95 with a large crushing allowance, the O-ring 96 can be brought into contact with the O-ring contact surface 27, but sufficient surface pressure cannot be applied to the gasket 95. Since the O-ring 96 and the O-ring contact surface 27 are in strong contact, the contact between the gasket 95 and the gasket contact surface 24 deteriorates. In particular, as shown in FIG. 8(B), the surface pressure at the tightening point 25d closest to the O-ring contact surface 27 is lower than the surface pressure at the other tightening points 25a - 25c. Therefore, even if the sealing performance of the O-ring 96 is improved, sufficient sealing performance cannot be obtained by the gasket 95.

[0038] As shown in Fig. 9(A), in the water pump 100 of another comparative example, the installation surface 102 of the pump body 101 is recessed more than the installation surface 104 of the discharge part 103, and a step is formed between the installation surface 102 of the pump body 101 and the installation surface 104 of the discharge part 103. The gasket contact surface 24 and the O-ring contact surface 27 of the crankcase 11 are formed on the same surface. A gasket 105 is held on the installation surface 102 of the pump body 101, and an O-ring 106 is held in the annular groove of the installation surface 104 of the discharge part 103. The thickness of the gasket 105 in the non-compressed state is formed to substantially match the step between the installation surface 102 of the pump body 101 and the installation surface 104 of the discharge part 103.

[0039] When the bolt is tightened, after the O-ring 106 slightly protruding from the installation surface 104 of the discharge part 103 contacts the O-ring contact surface 27, the gasket 105 contacts the gasket contact surface 24. The O-ring 106 strongly contacts the O-ring contact surface 27, but the crushing allowance of the gasket 105 becomes small and the contact between the gasket 105 and the gasket contact surface 24 deteriorates. In particular, as shown in Fig. 9(B), the surface pressure at the tightening point 25d closest to the O-ring contact surface 27 is significantly lower than the surface pressure at the other tightening points 25a - 25c. For this reason, sufficient sealing performance cannot be obtained by the gasket 105.

[0040] As shown in Fig. 10(A), in the water pump 41 of this embodiment, the installation surface 72 of the pump body 71 is recessed more than the installation surface 77 of the discharge part 76, and a step is formed between the installation surface 72 of the pump body 71 and the installation surface 77 of the discharge part 76. The gasket contact surface 24 and the O-ring contact surface 27 of the crankcase 11 are formed on the same surface. A gasket 81 is held on the installation surface 72 of the pump body 71, and an O-ring 87 is held in the annular groove of the installation surface 77 of the discharge part 76. The gasket 81 in the non-compressed state protrudes more than the installation surface 77 of the discharge part 76, and a gap is provided between the O-ring 87 and the O-ring contact surface 27.

[0041] The thickness of the gasket 81 on the installation surface 72 of the pump body 71 is formed to be larger than the step between the installation surface 72 of the pump body 71 and the installation surface 77 of the discharge part 76. For example, the thickness of the gasket 81 is 0.6 [mm], and the step between the installation surface 72 of the pump body 71 and the installation surface 77 of the discharge part 76 is formed to be 0.2 [mm]. Also, the crush allowance of the gasket 81 is formed to be larger than the gap between the O-ring 87 and the O-ring contact surface 27. The installation surface 72 of the pump body 71 is recessed more than the contact surface of the O-ring 87 with respect to the O-ring contact surface 27, and the crush allowance of the gasket 81 is formed so that the gap between the O-ring 87 and the O-ring contact surface 27 disappears during compression.

[0042] When the bolt is tightened, after the gasket 81 contacts the gasket contact surface 24, the gasket 81 is crushed and the O-ring 87 contacts the O-ring contact surface 27. By eliminating the gap between the O-ring 87 and the O-ring contact surface 27, the sealing performance of the O-ring 87 can be improved. Also, as shown in Fig. 10(B), the tightening force of the bolt is used for crushing the gasket 81, and a sufficient surface pressure can be applied to the gasket contact surface 24 as a whole. Therefore, even if the O-ring 87 is used for the installation of the discharge part 76 and the gasket 81 is used for the installation of the pump body 71, the sealing performance of the O-ring 87 and the gasket 81 can be sufficiently obtained.

[0043] In the above-described comparative example and other comparative examples, the surface pressure at the tightening portion 25d is lower than the surface pressure at the other tightening portions 25a - 25c. In this embodiment, although the surface pressure at the tightening portion 25d is improved, as a precaution, a convex portion 75 (see Fig. 6) for holding the gasket 81 is formed to avoid a portion where it is difficult for the surface pressure to act on the gasket 81. The convex portion 75 is formed at a position separated from the discharge part 76 more than the impeller shaft 74 (see Fig. 6). In this embodiment, the convex portion 75 is formed in front of the impeller shaft 74. Thereby, the gasket 81 can be stably held with respect to the installation surface 72 of the pump body 71.

[0044] As described above, according to the present embodiment, the crankcase 11 has a split structure including an upper case 21 and a lower case 22, and the pump body 71 of the water pump 41 is installed on the upper case 21 and the lower case 22 via a gasket 81. Since the highly durable gasket 81 is used as a sealing material for installing the pump body 71, the gasket 81 is not damaged by the edge of the mating surface 23 of the upper case 21 and the lower case 22. Therefore, even in the structure where the water pump 41 is installed across the upper case 21 and the lower case 22, the sealing performance can be improved with a simple and inexpensive configuration.

[0045] In addition, in the present embodiment, a gasket is used for installing the pump body, and an O-ring is used for installing the discharge portion. However, it is sufficient that at least a gasket is used for installing the pump body. A sealing material other than the O-ring may be used for installing the discharge portion.

[0046] Also, in the present embodiment, a metal gasket is used as the gasket. However, any gasket with high durability may be used.

[0047] Also, in the present embodiment, the gasket is held by the pump body of the water pump. However, the gasket may be held by the crankcase.

[0048] Also, in the present embodiment, the O-ring is held by the discharge portion of the water pump. However, the O-ring may be held by the crankcase.

[0049] Also, in the present embodiment, the crankcase has an upper and lower split structure including an upper case and a lower case. However, it is sufficient that the crankcase has a split structure including a first case and a second case. For example, the crankcase may have a front and rear split structure including a front case and a rear case, or a left and right split structure including a pair of side cases.

[0050] In addition, in this embodiment, although the engaging portion is formed inside the annular portion of the gasket, the position of the engaging portion is not particularly limited. The engaging portion may be formed outside the annular portion of the gasket.

[0051] In addition, in this embodiment, although the claw portion of the engaging portion is hooked on the convex portion, the shape of the engaging portion is not particularly limited. An annular rubber bush or the like may be attached to the opening of the engaging portion, and the rubber bush or the like may be hooked on the convex portion.

[0052] In addition, the engine cooling device can be appropriately applied to other vehicles in which an engine is installed in addition to the straddle-type vehicle, for example, automobiles, buggy-type three-wheeled vehicles, as well as jet skis, lawn mowers, outboard motors, etc. In addition, the straddle-type vehicle is not limited to all vehicles in which the rider rides in a posture straddling the seat, and also includes small scooter-type vehicles in which the rider rides without straddling the seat.

[0053] As described above, the engine cooling device (30) of this embodiment is an engine cooling device installed in the crankcase (11), and includes a water pump (41) that discharges cooling water toward the crankcase, and a gasket (81) used for installing the pump body (71) of the water pump. The crankcase has a split structure including a first case (upper case 21) and a second case (lower case 22), and a gasket is interposed between the first case and the pump body, and between the second case and the pump body. According to this configuration, the crankcase has a split structure including the first and second cases, and the pump body of the water pump is installed on the first and second cases via a gasket. Since a gasket with high durability is used as the sealing material for installing the pump body, the gasket is not damaged by the edges of the mating surfaces of the first and second cases. Therefore, even in a structure in which the water pump is installed across the first and second cases, the sealing performance can be improved with a simple and inexpensive configuration.

[0054] In the engine cooling device of this embodiment, an O-ring (87) used for installing the discharge part (76) of the water pump is provided, and the O-ring is interposed between the first case and the discharge part. A gasket is held on the installation surface (72) of the pump body, and the installation surface of the pump body is recessed from the contact surface of the O-ring with respect to the first case. According to this configuration, the O-ring is used for installing the discharge part that requires a relatively high sealing pressure, and the gasket is used for installing the pump body that requires a relatively low sealing pressure. Also, since the installation surface of the pump body is recessed from the contact surface of the O-ring, the gap between the O-ring and the first case can be eliminated, and the sealing performance of the O-ring can be improved.

[0055] In the engine cooling device of this embodiment, an O-ring is held on the installation surface (77) of the discharge part, and the installation surface of the pump body is recessed from the installation surface of the discharge part. According to this configuration, compared with the configuration of holding the O-ring on the first case, the O-ring can be easily held on the discharge part at low cost.

[0056] In the engine cooling device of this embodiment, the gasket in the non-compressed state protrudes from the installation surface of the discharge part. According to this configuration, when installing the water pump, the gasket contacts the crankcase before the O-ring, so the compression force is used to crush the gasket, and a sufficient surface pressure can be applied to the gasket as a whole.

[0057] In the engine cooling device of this embodiment, tightening parts (53a - 53e) are formed on the pump body and the discharge part, and a recess (78) is formed between the pump body and the discharge part in the water pump. According to this configuration, the water pump is thinned out by the recess, and its weight is reduced. Also, the flexibility near the recess is increased, the surface pressure near the tightening part is increased, and the sealing performance is improved.

[0058] In the engine cooling device of this embodiment, the tightening portion (53e) of the discharge portion is formed at one location on the side opposite to the concave portion with an O-ring interposed therebetween. According to this configuration, since the tightening portion of the pump body and the tightening portion of the discharge portion are separated with the concave portion therebetween, it becomes difficult for the tightening state of the tightening portion of the discharge portion to affect the tightening state of the tightening portion of the pump body, and the sealing performance of the gasket is improved.

[0059] In the engine cooling device of this embodiment, an impeller shaft (74) is provided on the pump body, a convex portion (75) for holding a gasket protrudes from the installation surface of the pump body, and an annular portion (82) formed so as to surround the impeller shaft and a hook portion (83) that catches on the convex portion inside the annular portion are formed on the gasket. According to this configuration, the holding portion of the gasket is hidden inside the annular portion and does not affect the appearance. The falling of the gasket during assembly can be suppressed by the hooking structure, and the assemblability of the gasket can be improved.

[0060] In the engine cooling device of this embodiment, the convex portion is separated from the discharge portion by more than the impeller shaft. According to this configuration, the convex portion can be formed while avoiding a location where surface pressure hardly acts on the gasket.

[0061] Although this embodiment has been described, as another embodiment, a combination of the above-described embodiment and modification examples, either in whole or in part, may be used.

[0062] Furthermore, the technology of the present invention is not limited to the above-described embodiment, and various changes, substitutions, and modifications may be made without departing from the spirit of the technical idea. Further, if the technical idea can be realized in another way by technological progress or another derived technology, it may be implemented using that method. Therefore, the scope of the claims covers all embodiments that can be included within the scope of the technical idea.

Explanation of Reference Numerals

[0063] 10: Engine 11: Crankcase 21: Upper case (first case) 22: Lower case (second case) 30: Cooling device 41: Water pump 53a - 53e: Tightening part 71: Pump body 72: Installation surface of the pump body 74: Impeller shaft 75: Convex part 76: Discharge part 77: Installation surface of the discharge part 78: Concave part 81: Gasket 82: Annular part 83: Hanging part 87: O-ring

Claims

1. An engine cooling device installed in a crankcase, comprising: a water pump that discharges cooling water toward the crankcase; a gasket used for installing the pump body of the water pump; an O-ring used for installing the discharge part of the water pump, wherein the crankcase has a split structure including a first case and a second case; the gasket is interposed between the first case and the pump body and between the second case and the pump body; the O-ring is interposed between the first case and the discharge part; the gasket is held on the installation surface of the pump body, and the installation surface of the pump body is recessed from the contact surface of the O-ring with respect to the first case. An engine cooling device characterized by this.

2. The O-ring is held on the installation surface of the discharge part, and the installation surface of the pump body is recessed from the installation surface of the discharge part. The engine cooling device according to claim 1, characterized by this.

3. The gasket in an uncompressed state protrudes from the installation surface of the discharge part. The engine cooling device according to claim 2, characterized by this.

4. A tightening part is formed on the pump body and the discharge part; A recess is formed between the pump body and the discharge part in the water pump. The engine cooling device according to any one of claims 1 to 3, characterized by this.

5. The tightening part of the discharge part is formed at one position on the opposite side of the recess with the O-ring interposed therebetween. The engine cooling device according to claim 4, characterized by this.

6. An impeller shaft is provided on the pump body; a convex part that holds the gasket protrudes from the installation surface of the pump body; The gasket is formed with an annular part formed so as to surround the impeller shaft and a hook part that hooks on the convex part inside the annular part. The engine cooling device according to any one of claims 1 to 5, characterized by this.

7. The convex part is spaced apart from the discharge part more than the impeller shaft. The engine cooling device according to claim 6, characterized by this.

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