Belt cover structure for internal combustion engine

Abstract

Provided is a belt cover which is for an internal combustion engine and which efficiently discharges water from a drain hole and has excellent sealing properties. The belt cover has: a water pump 30 which is disposed on one side surface of a cylinder block CB and has a drain hole 35; an oil pump case OP covering the inner side of a timing belt TB; and a lower cover 9 covering the outside of the timing belt TB. The oil pump case OP and the lower cover 9 form a lower case 90 by being fixed via a seal member 40. A guide rib 91, which separates drainage from the drain hole 35 from the timing belt TB while guiding the drainage, and a discharge port 92, for discharging drainage from the lower case 90 at the bottom end of the lower case 90, are formed inside the lower case 90, and the drainage from the drain hole 35 is guided by the guide rib 91 and thereby guided to the discharge port 92.

Description

[Technical Field]

[0001] The present invention relates to a belt cover structure for an internal combustion engine for protecting a timing belt attached to the internal combustion engine. [Background technology]

[0002] Some internal combustion engines installed in vehicles use a timing belt (or transmission belt such as a timing chain) to transmit the rotational power of the crankshaft to the camshaft in conjunction with the timing belt. To protect the timing belt from water and dust, a belt cover is sometimes placed on the cylinder block of the internal combustion engine to cover the timing belt. Generally, belt covers are required to have a waterproof and dustproof seal.

[0003] In Patent Document 1, a labyrinth-shaped drainage structure is provided under the timing belt cover and under the engine body to drain water that accumulates inside the timing belt cover. However, if water accumulates inside the timing belt cover, it may splash onto the timing belt, causing deterioration of the timing belt.

[0004] In Patent Document 2, a guide is provided that slopes from the drain hole of the water pump located inside the timing belt cover toward the internal combustion engine body. Water discharged from the drain hole is first guided along the guide toward the internal combustion engine body and then below the crank pulley. This prevents water from splashing on the timing belt. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Publication No. 2529170 [Patent Document 2] Publication number 2-31539 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in Patent Document 1, a large drain port is required to improve drainage so that water does not accumulate inside the cover, and therefore a complex labyrinth structure must be provided to prevent foreign matter from entering, making it difficult to achieve both drainage and prevention of foreign matter entry. Configuring a guide that is inclined toward the internal combustion engine body, as in Patent Document 2, requires the formation of a recess on the internal combustion engine body to accommodate the guide, which places restrictions on the layout of the surface of the internal combustion engine body. Therefore, this method cannot be adopted if it is not possible to form such a recess.

[0007] Additionally, it is possible to form an opening in the timing belt cover near the water pump drain hole to facilitate maintenance of the water pump located inside the timing belt cover. However, there is a risk that water or foreign matter may enter through the opening. As such, the belt cover is required to efficiently drain water from the drain hole and to have a waterproof and dustproof seal without forming a recess for drainage in the internal combustion engine body.

[0008] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a belt cover for an internal combustion engine that efficiently drains water from the drain holes and has excellent sealing properties. [Means for solving the problem]

[0009] In order to achieve this object, the invention according to claim 1 is a belt cover structure for an internal combustion engine 1, which houses at least a part of a timing belt TB arranged on one side of an internal combustion engine body (a cylinder block CB in an embodiment (hereinafter the same in this paragraph)), and includes a water pump 30 arranged on the one side and having a drain hole 35 for draining water, an inner cover member (oil pump case OP) covering the timing belt TB on a side closer to the internal combustion engine 1 than the timing belt TB, and an inner cover member (oil pump case OP) which is arranged on the one side and has a drain hole 35 for draining water, and and an outer cover member (lower cover 9) that covers the timing belt TB on the far side, and the inner cover member and the outer cover member are fixed together via a sealing member 40 to form a case (lower case 90), and inside the case there is formed a guide rib 91 that guides drainage water from the drain hole 35 downwardly while keeping it away from the timing belt TB, and a discharge port 92 at the lower end of the case for discharging the drainage water from the case, and the drainage water from the drain hole 35 is guided by the guide rib 91 to be led to the discharge port 92.

[0010] In this way, the drainage water from the water pump drain hole is guided by the guide rib formed inside the case and directed to the drain port. By intentionally directing the drainage water from the water pump drain hole into the case and directing it to the bottom of the case before draining it, there is no need to provide a drainage opening near the drain hole. Furthermore, because the inner cover member and the outer cover member are fixed via a seal member, excellent sealing is achieved. This allows for efficient drainage of water from the drain hole while preventing water and dust from entering near the drain hole, providing an internal combustion engine belt cover with excellent sealing properties for waterproofing and dustproofing.

[0011] The invention of claim 2 is a belt cover structure for an internal combustion engine as described in claim 1, characterized in that a sloping wall 93a sloping toward the discharge port 92 is formed in the lower part of the inner wall 93 of the case, the lower end 91a of the guide rib 91 is formed toward the sloping wall 93a, and drainage from the drain hole 35 is guided to the discharge port 92 via the guide rib 91 and the sloping wall 93a.

[0012] In this way, by forming the lower end of the guide rib toward the inner wall of the case, it is possible to guide the drainage water in a direction away from the timing belt. In addition, the inclination of the inclined wall allows the drainage water to be efficiently guided to the drain port.

[0013] The invention of claim 3 is a belt cover structure for an internal combustion engine as described in claim 1 or 2, characterized in that the inner cover member is assembled to the internal combustion engine body adjacent to and below the water pump 30, an inclined surface 89 is formed between the inner cover member and the internal combustion engine body, and drainage from the drain hole 35 is guided along the inclined surface 89 into the interior of the case.

[0014] In this way, when the inner cover member is assembled to the internal combustion engine body adjacent to the lower side of the water pump, if the drainage from the water pump's drain hole is configured to be guided into the inside of the case along the inclined surface formed between the inner cover member and the internal combustion engine body, the drainage from the water pump's drain hole can be smoothly guided into the inside of the case.

[0015] The invention of claim 4 is the belt cover structure for an internal combustion engine described in claim 3, characterized in that the outer cover member protrudes beyond the inner cover member toward the internal combustion engine body at a position opposite the inclined surface 89, and a protruding portion 94a is formed which is fixed to the internal combustion engine body via the sealing member 40, and the inclined surface 89 is separated from the outside of the case by the protruding portion 94a.

[0016] In this way, the protruding portion of the outer cover member extends beyond the inner cover member and is fixed to the internal combustion engine body via the sealing member, so that the protruding portion can separate the sloped surface that guides the drainage water from the outside of the case, thereby improving the waterproof and dustproof effects of the case.

[0017] The invention of claim 5 is a belt cover structure for an internal combustion engine described in any one of claims 1 to 4, wherein the case 90 houses a drive pulley 15 attached to the crankshaft 10, a sloped wall 93a sloped toward the discharge port 92 is formed in the lower part of the case 90, the guide rib 91 is formed on the inner cover member, a vibration suppression rib (rib 95a) extending radially of the drive pulley 15 to suppress vibration of the inner cover member is formed on the inner cover member below the lower end of the guide rib 91, and drainage from the drain hole 35 is guided by the guide rib 91 and then led to the sloped wall 93a via the vibration suppression rib.

[0018] In this way, the vibration suppression rib formed to suppress vibration of the inner cover member extends radially of the drive pulley attached to the crankshaft and is formed below the lower end of the guide rib, and the drainage water is guided by the guide rib and then directed to the inclined wall via the vibration suppression rib, which further directs the drainage water in a direction away from the timing belt and prevents the drainage water from contacting the timing belt.

[0019] The invention according to claim 6 is a belt cover structure for an internal combustion engine according to any one of claims 1 to 5, characterized in that the inner cover member is part of an oil pump case OP that houses an oil pump.

[0020] In this way, by making the inner cover member a part of the oil pump case, the inner cover member can also serve as a housing for the oil pump, and the inner cover member can be used effectively. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a diagram showing a timing belt in an internal combustion engine and a belt cover disposed inside the timing belt; [Figure 2] FIG. 2 is a diagram showing a belt cover disposed on the outside of a timing belt in an internal combustion engine. [Figure 3] FIG. 2 is a side view of the internal combustion engine showing a state in which the belt cover is assembled. [Figure 4] FIG. 2 is an enlarged perspective view showing the configuration of the outer surface of the oil pump case. [Figure 5] FIG. 4 is a side view showing the flow of drainage from the oil pump case. [Figure 6] FIG. 2 is a perspective view of the lower cover as seen from the inside. [Figure 7] FIG. 2 is a perspective view of the lower cover as seen from the outside. [Figure 8] 4A and 4B are diagrams illustrating a structure in which an oil pump case, a lower cover, and a cylinder block are sealed to one another. DETAILED DESCRIPTION OF THE INVENTION

[0022] A preferred embodiment of the belt cover structure for an internal combustion engine 1 of the present invention will be described in detail below with reference to the drawings. Note that this embodiment will be described taking as an example a case where the internal combustion engine 1 is installed vertically. In addition, the direction in which the crankshaft 10 and camshafts 11, 12, 13, and 14 of the internal combustion engine 1 extend will be referred to as the axial direction, the vertically upward and downward directions will be referred to as the vertical direction, and the front-to-rear direction of a vehicle in which the internal combustion engine 1 is installed vertically will be referred to as the front-to-rear direction.

[0023] An outline of the structure of the timing belt TB of the internal combustion engine 1 and the structure of the belt cover of the internal combustion engine 1 will be described using Figures 1 and 2. Figure 1 is a diagram showing the timing belt TB of the internal combustion engine 1 and a belt cover arranged on the inside of the timing belt TB. Figure 2 is a diagram showing the belt cover arranged on the outside of the timing belt TB of the internal combustion engine 1. Note that the inside and outside here refer to the side of the timing belt TB that is closer to the cylinder head CH, CH or cylinder block CB of the internal combustion engine 1 as the inside, and the opposite side as the outside.

[0024] As shown in Figure 1, a crankshaft 10 and camshafts 11, 12, 13, and 14 are disposed to protrude from cylinder heads CH, CH and a cylinder block CB on one side of the internal combustion engine 1. The crankshaft 10 and the camshafts 11, 12, 13, and 14 are connected to drive pulleys 15, 16, 17, 18, and 19, respectively. A timing belt TB is wound around the drive pulleys 15, 16, 17, 18, and 19 and the other pulleys. This causes the crankshaft 10 and the camshafts 11, 12, 13, and 14 to rotate in unison.

[0025] As shown in Figures 1 and 2, the timing belt TB is protected by a belt cover. The belt cover is attached to one side of the internal combustion engine body. The belt cover of this embodiment has a front inner cover 2, a rear inner cover 3, an upper outer cover 4, a lower outer cover 5, a rear outer cover 7, a side mount bracket 8, and a lower cover 9. The spaces between the covers are sealed by disposing sealing members or the like, so that the belt cover as a whole accommodates the timing belt TB in a liquid-tight state.

[0026] The procedure for assembling the belt cover of this embodiment will be described with reference to Figures 1 and 2. First, as a premise, as shown in Figure 1, before the timing belt TB is assembled to the internal combustion engine 1, the front inner cover 2 and the rear inner cover 3 are assembled to the cylinder heads CH, CH. Also, the oil pump case OP is assembled to the cylinder block CB.

[0027] As shown in FIG. 2 , the lower cover 9 is attached around the crankshaft 10, and the side mount bracket 8 is attached above and adjacent to the lower cover 9. Then, the rear outer cover 7 is attached above and adjacent to the side mount bracket 8, covering the outside of the drive pulleys 18, 19 of the camshafts 13, 14. The lower outer cover 5 is attached above and adjacent to the side mount bracket 8, and the upper outer cover 4 is attached above and adjacent to the lower outer cover 5. Here, the upper outer cover 4 and the lower outer cover 5 together constitute the front outer cover 6, which covers the outside of the drive pulleys 16, 17 of the camshafts 11, 12. The front outer cover 6 is located forward of the rear outer cover 7.

[0028] Fig. 3 is a side view of the internal combustion engine 1 showing the state in which the belt cover is attached. As shown in Fig. 3, when the belt cover is attached, a crank pulley 20 is connected to the crankshaft 10, piping 21 is arranged on the outside of the front outer cover 6 and the rear outer cover 7, and piping 22 is arranged on the outside of the side mount bracket 8.

[0029] Next, the lower case 90 and its surrounding structure of the belt cover structure of the internal combustion engine 1 of this embodiment will be described in detail. The lower case 90 has an oil pump case OP that covers the timing belt TB on a side closer to the internal combustion engine 1 than the timing belt TB, and a lower cover 9 that covers the timing belt TB on a side farther from the internal combustion engine 1 than the timing belt TB. The lower cover 9 is attached to the oil pump case OP using fastening members such as bolts. The lower case 90 houses the timing belt TB that is arranged on one side of the internal combustion engine 1. Specifically, it houses the drive pulley 15 attached to the crankshaft 10 and the timing belt TB around the drive pulley 15.

[0030] The following describes in particular the drainage structure and its surrounding structure, in which water discharged from water pump 30 passes through the interior of lower case 90, which is disposed adjacent to and below water pump 30, and is discharged below lower case 90. Water pump 30 is disposed adjacent to and on the inside (farther in the crankshaft direction) of side mount bracket 8. Water pump 30 is provided with drainage holes 35 above lower case 90 for draining water.

[0031] The detailed configuration of the oil pump case OP will be described using Figures 4 and 5. Figure 4 is an enlarged perspective view showing the configuration of the outer surface of the oil pump case OP. Note that Figure 4 also shows the structure of the seal member 40 sandwiched between the lower cover 9 and the oil pump case OP. Figure 5 is a side view showing the flow of drainage water from the oil pump case OP.

[0032] The oil pump case OP and the lower cover 9 are fixed with fastening members such as bolts via a sealing member 40 to form a lower case 90. The oil pump case OP is assembled to the cylinder block CB, and the lower cover 9 is assembled to the oil pump case OP.

[0033] Ribs for various purposes are formed on the outer surface of the oil pump case OP (the surface facing the lower cover 9). Specifically, the oil pump case OP has a guide rib 91 that guides the drainage water from the drain hole 35 downward in the lower case 90 while separating it from the timing belt TB, and ribs 95a, 95b, and 95c that extend radially in the radial direction of the drive pulley 15 to suppress vibration of the oil pump case OP.

[0034] A drain port 92 is formed at the lower end of the lower case 90 to allow drainage water from the drain hole 35 to be discharged from the lower case 90. The drainage water from the drain hole 35 is guided to the drain port 92 via a guide rib 91.

[0035] The oil pump case OP and the lower cover 9 have mating surfaces 96a, 96b, respectively, that can be mated to each other. A recessed groove U (see FIG. 5) for fitting the seal member 40 is formed in the mating surface 96a of the oil pump case OP. Similarly, a recessed groove (not shown) for fitting the seal member 40 is formed in the lower cover 9. The inner surface separated from the outside by the mating surface 96a of the oil pump case OP constitutes an inner wall 93 of the lower case 90. The inner wall 93 is positioned away from the timing belt TB so that the timing belt TB does not come into contact with it.

[0036] In this embodiment, a protrusion 98 for arranging accessories is provided at the lower end of the oil pump case OP. In this case, as in this embodiment, by forming the guide rib 91 so that it gradually moves away from the timing belt TB as it goes downward, space for arranging accessories is secured and water is prevented from getting on the timing belt TB, which is preferable. In addition, in this embodiment, the wastewater guided by the rib 95a toward the inclined wall 93a flows from the rib surface toward the lower cover 9 and then toward the discharge port 92, but this protrusion 98 prevents the water flow from flowing toward the timing belt, allowing it to be quickly discharged from the discharge port 92. Ribs may be provided in place of the protrusions 98 to suppress vibrations and also to block drainage water from flowing toward the belt. By providing this protrusion 98 or rib, it is possible to prevent foreign matter or water from entering through the outlet, and it is also possible to obtain the effect of reducing vibration noise.

[0037] In this embodiment, a sloping wall 93a sloping toward the discharge port 92 is formed in a lower portion of the lower case 90, which is also a lower portion of the inner wall 93 on the oil pump case OP side. A lower end 91a of the guide rib 91 is formed toward the sloping wall 93a. Therefore, drainage water from the drain hole 35 is guided to the discharge port 92 via the guide rib 91 and the sloping wall 93a.

[0038] Furthermore, the rib 95a is formed adjacent to the lower side of the lower end of the guide rib 91. The rib 95a is formed to slope downward toward the inclined wall 93a. Therefore, the drainage water from the drain hole 35 is guided by the guide rib 91 and then more reliably led to the inclined wall 93a via the rib 95a.

[0039] The oil pump case OP is formed with a fastening portion 97 for fastening the pulley 25 (see FIG. 1). Part of the fastening portion 97 is omitted in FIGS. 4 and 5. On the cylinder block CB side of the fastening portion 97 in the axial direction, between the water drain hole 35 and the guide rib 91, an inclined surface 89 is formed between the oil pump case OP and the cylinder block CB, inclining from the water drain hole 35 in the direction from the guide rib 91. As a result, drained water from the water drain hole 35 is guided into the lower case 90 along the inclined surface 89 formed between the oil pump case OP and the cylinder block CB. Here, it is preferable that the inclined surface 89 is formed so as to be continuous with both the oil pump case OP and the cylinder block CB, but the inclined surface 89 may be formed on either one of them.

[0040] 5, the drainage flow path of the drain hole 35 is made up of the inclined surface 89, the guide rib 91, the rib 95a, and the inclined wall 93a. The inclined wall 93a is sealed by the sealing member 40. With this configuration, the drainage water from the drain hole 35 is first guided into the lower case 90 by the inclined surface 89, passes through the guide rib 91, the rib 95a, and the inclined wall 93a, and then reaches the discharge port 92 is led to.

[0041] 6 to 8, the sealing structure near the inclined surface 89 when the lower cover 9 is assembled to the oil pump case OP will be described. Fig. 6 is a perspective view of the lower cover 9 as seen from the inside. Fig. 7 is a perspective view of the lower cover 9 as seen from the outside. Fig. 8 is a diagram explaining the structure by which the oil pump case OP, the lower cover 9, and the cylinder block CB are sealed from one another.

[0042] As shown in Figure 6, the lower cover 9 has a mating surface 96b that mates with a mating surface 96a of the oil pump case OP to separate the interior and exterior of the lower case 90. The seal member 40 fits into a recessed groove formed in the mating surface 96b. The lower cover 9 has a side wall 94 that separates the interior and exterior of the lower cover 9. The side wall 94 is formed to surround the periphery of the lower cover 9 except for the portion where the lower cover 9 is assembled to the side mount bracket 8.

[0043] The side wall 94 of the lower cover 9 is configured to extend in the crankshaft direction. Here, protrusions 94a and 94b are formed on the upper end of the side wall 94. Although the protrusions 94a and 94b have different shapes, they have similar functions, so only the structure around the protrusion 94a will be described.

[0044] The protruding portion 94a is a part of the side wall 94 that extends further in the axial direction than the other parts of the side wall 94. A large portion of a mating surface 96b formed at the axial end of the side wall 94 on the internal combustion engine body side abuts against the mating surface 96a of the oil pump case OP. Meanwhile, the protruding portion 94a extends beyond the oil pump case OP and reaches near the cylinder block CB, and is fixed by being pressed against the cylinder block CB via the seal member 40. In this way, the protruding portion 94a is a portion formed by protruding the side wall 94 in the direction of the cylinder block CB by a length that abuts against the cylinder block CB. The protruding portion 94a also covers a position facing forward with respect to the inclined surface 89 (portion B in FIG. 5).

[0045] 7, a mating surface 96c for the side mount bracket 8 is formed on the outer peripheral surface of the upper end of the lower cover 9 so as to surround the oil pump case OP. A lower seal member 41 that seals the lower cover 9 and the side mount bracket 8 is disposed on the mating surface 96c. In addition, the upper end of the side wall of the lower cover 9 has a protrusion 94b that protrudes toward the internal combustion engine 1.

[0046] The outer surface of the lower cover 9 is provided with multiple vibration-reducing ribs to increase the rigidity of the lower cover 9 and suppress vibration of the lower cover 9. Four fan-shaped first convex ribs 99b are formed radially on the outer surface of the lower cover 9, centered on the opening 99a for the crankshaft 10. Five I-shaped second convex ribs 99c are also formed on the outer surface of the lower cover 9, adjacent to the first convex ribs 99b in the circumferential direction. The second convex ribs 99c protrude lower than the first convex ribs 99b. The second convex ribs 99c, located between the first convex ribs 99b, increase the rigidity of the lower cover 9, suppressing membrane vibration of the lower cover 9 caused by the drive of the crankshaft 10 and the timing belt TB, and suppressing vibration of the mating surface 96c. This maintains the sealing performance of the mating surface 96c without the need for additional fastening bolts or the like, and also reduces deterioration of the lower seal member 41 due to vibration. The number of ribs is not limited to that of the present embodiment. Also, in the above-described FIG. 6, vibration suppression ribs are formed in a manner corresponding to that of FIG.

[0047] The protruding portion 94a of the lower cover 9 abuts not only against the oil pump case OP but also against the cylinder block CB, and is fixed via the seal member 40. This sealing structure will be explained using the drawings. Figure 8 is a diagram explaining the structure in which the oil pump case OP, the lower cover 9, and the cylinder block CB are sealed from one another. Figure 8 is a view seen from the direction A in Figures 4 and 6.

[0048] As shown in Figure 8, the protruding portion 94a is a part of the side wall 94 that protrudes beyond the oil pump case OP toward the cylinder block CB. In this embodiment, the protruding portion 94a is formed at the upper end of the side wall 94. The cylinder block CB side of the protruding portion 94a is fixed via the seal member 40. Furthermore, since the seal member 40 is disposed continuously with the lower end of the protruding portion 94a, the protruding portion 94a is also fixed to the oil pump case OP via the seal member 40. In this way, due to the presence of the protruding portion 94a, the lower cover 9 is fixed to both the oil pump case OP and the cylinder block CB via the seal member 40.

[0049] As described above, according to this embodiment, drainage water from the drain hole 35 of the water pump 30 is guided by the guide rib 91 formed inside the lower case 90 and directed to the discharge port 92. The drainage water from the drain hole 35 of the water pump 30 is intentionally directed into the lower case 90 and then guided to the bottom of the lower case 90 before being drained. This eliminates the need to provide an opening for drainage near the drain hole 35. Furthermore, since the oil pump case OP and the lower cover 9 are fixed via the seal member 40, excellent sealing performance is achieved. This allows water to be efficiently discharged from the drain hole 35 while preventing water and dust from entering near the drain hole 35, providing a belt cover for an internal combustion engine with excellent sealing performance for waterproofing and dustproofing.

[0050] Furthermore, according to this embodiment, the lower ends of the guide ribs 91 are formed toward the inner wall 93 of the lower case 90, so that the drained water can be guided in a direction away from the timing belt TB. Furthermore, the inclination of the inclined wall 93a allows the drained water to be efficiently guided to the discharge port 92.

[0051] Furthermore, according to this embodiment, when the oil pump case OP is assembled to the cylinder block CB adjacent to and below the water pump 30, the drainage water from the drain holes 35 of the water pump 30 is guided into the interior of the lower case 90 along the inclined surface 89 formed between the oil pump case OP and the cylinder block CB. This allows the drainage water from the drain holes 35 of the water pump 30 to be smoothly guided into the interior of the lower case 90.

[0052] Furthermore, according to this embodiment, the protrusion 94a of the lower cover 9 extends beyond the oil pump case OP and is fixed to the cylinder block CB via the seal member 40. This allows the protrusion 94a to separate the inclined surface 89, which guides drainage, from the outside of the lower case 90. This improves the waterproof and dustproof properties of the lower case 90.

[0053] Furthermore, according to this embodiment, the rib 95a formed to suppress vibration of the oil pump case OP extends in the radial direction of the drive pulley 15 attached to the crankshaft 10 and is formed below the lower end of the guide rib 91. After being guided by the guide rib 91, the drained water is led to the inclined wall 93a via the rib 95a. This allows the drained water to be further led in a direction away from the timing belt TB, thereby preventing the drained water from splashing on the timing belt TB.

[0054] Furthermore, according to this embodiment, the member to which the lower cover 9 is attached is made a part of the oil pump case OP. This allows the member to which the lower cover 9 is attached to also function as a housing for the oil pump, and the member to which the lower cover 9 is attached can be used effectively.

[0055] The present invention is not limited to the embodiment described above and can be embodied in various forms. In the above embodiment, a timing belt TB is used as a transmission belt for transmitting drive power from the crankshaft 10 to the camshafts 11, 12, 13, and 14, but the present invention is not limited to this. For example, as an example of the power transmission structure of the internal combustion engine 1, a chain transmission mechanism may be used in which a transmission belt made of a timing chain is stretched between a crankshaft driving wheel and a camshaft driven wheel made of sprockets.

[0056] In the above embodiment, the member to which the lower cover 9 is attached is a part of the oil pump case OP that houses the oil pump, but this is not limiting. It may be a case that houses accessories other than the oil pump, or an additional cover may be disposed on the outside of the oil pump case OP, and the lower cover 9 may be attached to that cover. [Explanation of symbols]

[0057] 1...Internal combustion engine 9...Lower cover (outer cover member) 30...Water pump 35...Drain hole 40...Sealing member 89…Slope surface 90...Lower case (case) 91...Guide rib 92...Exhaust port 93a…slanted wall 94a...Protruding part 95a...Rib (vibration suppression rib) CB: Cylinder block CH...Cylinder head OP...Oil pump case (inner cover material) TB...Timing belt

Claims

1. A belt cover structure for an internal combustion engine that accommodates at least a portion of a timing belt disposed on one side of a main body of the internal combustion engine, a water pump disposed on the one side and having a drain hole for draining water; an inner cover member that covers the timing belt on a side closer to the internal combustion engine than the timing belt; an outer cover member that covers the timing belt on a side farther from the internal combustion engine than the timing belt, the inner cover member and the outer cover member are fixed to each other via a seal member to form a case; A guide rib is formed inside the case to guide the drainage water from the drain hole downwardly while separating the drainage water from the timing belt, and a drain port is formed at a lower end of the case to drain the drainage water from the case, A belt cover structure for an internal combustion engine, characterized in that drainage water from the water drain hole is guided by the guide rib and directed to the exhaust port.

2. A sloped wall that slopes toward the outlet is formed in a lower portion of the case, The lower end of the guide rib is formed toward the inclined wall, 2. The belt cover structure for an internal combustion engine according to claim 1, wherein drainage water from said drain hole is guided to said discharge port via said guide rib and said inclined wall.

3. The inner cover member is attached to the internal combustion engine body adjacent to a lower portion of the water pump, An inclined surface is formed between the inner cover member and the internal combustion engine body, 3. The belt cover structure for an internal combustion engine according to claim 1, wherein drainage from said drain hole is guided along said inclined surface into the inside of said case.

4. the outer cover member is provided with a protruding portion that protrudes beyond the inner cover member toward the internal combustion engine body at a position facing the inclined surface and is fixed to the internal combustion engine body via the seal member, 4. The belt cover structure for an internal combustion engine according to claim 3, wherein the inclined surface is separated from the outside of the case by the protruding portion.

5. The case accommodates a drive pulley attached to a crankshaft, A sloped wall that slopes toward the outlet is formed in a lower portion of the case, The guide rib is formed on the inner cover member, A vibration suppression rib extending in a radial direction of the drive pulley for suppressing vibration of the inner cover member is formed on the inner cover member below a lower end of the guide rib, 5. The belt cover structure for an internal combustion engine according to claim 1, wherein the drainage water from the drain hole is guided by the guide rib and then led to the inclined wall via the vibration suppression rib.

6. 6. The belt cover structure for an internal combustion engine according to claim 1, wherein the inner cover member is a part of an oil pump case that houses an oil pump.

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