Internal combustion engine

Abstract

To provide an internal combustion engine having a drainage structure which can discharge water to the outside from the inside of an internal space which is formed inside a belt cover for covering a timing belt arranged at a side part of the internal combustion engine, and on the other hand, can avoid the intrusion of water therein, and capable of avoiding an excess of man-hours for constituting the drainage structure.SOLUTION: An internal combustion engine has an annular seal material which is gripped between an external peripheral part of a belt cover and a side face of an engine body. A seal protrusion protruding toward the belt cover is formed in a lower region of the seal material, and a cover recess which opposes the seal protrusion, forms a clearance between the side face of the seal protrusion and itself, and forms a drainage path including the clearance, is formed at the belt cover.SELECTED DRAWING: Figure 10

Description

Technical Field

[0004]

[0001] The present invention relates to an internal combustion engine. For example, it relates to an internal combustion engine in which a drain passage is formed in a lower part of a belt cover that covers a timing belt provided on a side portion of an engine body.

Background Art

[0002] There is an internal combustion engine in which a timing belt for transmitting torque from a crankshaft to a camshaft is arranged outside (side portion) of an engine body. When such an internal combustion engine is mounted on a vehicle, if foreign matters such as sand, dust, and water scooped up by vehicle tires adhere to the timing belt, deterioration of the timing belt is accelerated. Therefore, in many cases, a timing belt cover that covers the timing belt is attached to the engine body, thereby avoiding entry of foreign matters into a space (internal space) formed between the timing belt cover and the engine body.

[0003] On the other hand, when water is generated in the internal space due to condensation, or when water enters the internal space from a gap formed between the timing belt cover and the engine body, it is necessary to discharge the water to the outside. Therefore, in one of the conventional internal combustion engines, a drain structure is formed in a lower part of the timing belt cover. Specifically, a labyrinth-like water discharge path (drain passage) including a plurality of bent portions is formed by a sealing material inserted between the timing belt cover and the engine body, a drain hole formed in the timing belt cover, a baffle plate, and the like. According to this drain passage, it becomes difficult for foreign matters to enter the internal space, while it becomes possible to discharge water from the internal space (for example, refer to Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] However, in order to form the aforementioned drainage channels, it is necessary to provide drainage holes and baffle plates, etc., in the timing belt cover. Therefore, there is a risk that the man-hours required for manufacturing the timing belt cover (including design changes) will become excessive.

[0006] This invention was conceived in view of these points, and aims to provide an internal combustion engine that has a drainage passage for discharging water from the internal space of the timing belt cover and that avoids excessive manufacturing costs. [Means for solving the problem]

[0007] To solve the above problems, the internal combustion engine according to the first invention of the present invention includes a belt cover that covers a timing belt provided on the side of the engine body, and an annular sealing material that is sandwiched between the outer circumference of the belt cover and the side surface of the engine body. A sealing projection is provided in the lower region of the sealing material that protrudes toward the belt cover. The belt cover is provided with a cover recess that faces the sealing projection and forms a gap between itself and the side surface of the sealing projection, and which includes the gap and forms a drainage passage for draining water inside the belt cover.

[0008] A second aspect of the present invention is an internal combustion engine according to the first aspect of the present invention, wherein the belt cover has a lower flange extending vertically downward, and the cover recess is included in the lower flange.

[0009] A third invention of the present invention is an internal combustion engine according to the first or second invention, wherein the belt cover has a receiving surface that faces the lower surface of the seal projection and forms the drainage passage between itself and the lower surface.

[0010] The fourth invention of the present invention is an internal combustion engine according to the third invention, wherein the receiving surface extends beyond at least one of the sides of the lower surface. [Effects of the Invention]

[0011] The gap formed between the seal protrusion and the cover recess creates a drainage channel that includes multiple bending points. Therefore, according to the first invention, it is possible to discharge water from the internal space, while it becomes extremely difficult for water (and other foreign matter) to enter the internal space by moving backward through the drainage channel. In addition, since the drainage channel is formed by the seal protrusion and the cover recess, it is possible to construct the drainage channel by simply changing the shape of the belt cover and the sealing material, thus avoiding excessive man-hours required to provide the drainage channel.

[0012] In the second invention, water that passes through the gap (uneven path) between the seal protrusion and the cover recess moves downward (falls) through the gap between the lower flange and the engine body. In other words, if water were to enter the internal space from the outside to the inside, it would need to move upward through the gap between the lower flange and the engine body before reaching the drainage path formed by the seal protrusion and the cover recess. Therefore, according to the second invention, it becomes even more difficult for water to enter the internal space.

[0013] In the third invention, water that has passed through the uneven path reaches the receiving surface. In other words, the movement of water that has passed (fallen) between the respective sides of the seal protrusion and cover recess is temporarily obstructed by the receiving surface. That is, the receiving surface forms a bending point in the drainage section. Therefore, according to the third invention, it becomes even more difficult for water to enter the internal space.

[0014] In the fourth invention, water that has passed through the uneven path and reached the receiving surface must move along the receiving surface that extends beyond the sides of the lower surface of the sealing protrusion before falling off the receiving surface. That is, the path of water passing through the drainage channel becomes more complex. Consequently, according to the fourth invention, it becomes even more difficult for water to enter the internal space. [Brief explanation of the drawing]

[0015] [Figure 1]Exploded perspective view of an internal combustion engine according to an embodiment of the present invention, a timing belt cover (belt cover) fixed to the internal combustion engine, and a sealing material. [Figure 2] Front view of the lower part of the belt cover and the sealing material. [Figure 3] Rear view of the lower part of the belt cover. [Figure 4] Front view of the lower part of the sealing material. [Figure 5] Exploded perspective view of a convex portion of the sealing material constituting a drain passage and a belt cover covering the convex portion. [Figure 6] Exploded perspective view of a concave portion of the belt cover constituting a drain passage and a sealing material covering the concave portion. [Figure 7] Cross-sectional view of the lower part of the sealing material that has not been deformed. [Figure 8] Cross-sectional view including convex and concave portions at the lower part of the belt cover and the sealing material fixed to the internal combustion engine. [Figure 9] Cross-sectional view not including convex and concave portions at the lower part of the belt cover and the sealing material fixed to the internal combustion engine. [Figure 10] Perspective view showing the path of water flowing through the drain passage. [Figure 11] Perspective view seen from the same viewpoint as FIG. 10 showing the path of water flowing through the drain passage according to a modification of the present embodiment. [Figure 12] Cross-sectional view showing a cross-section similar to FIG. 8 including convex and concave portions at the lower part of the belt cover and the sealing material according to this modification.

Embodiments for Carrying Out the Invention

[0016] Embodiments of the present invention will be described with reference to FIGS. 1 to 10. The same reference numerals (reference numbers) in the description denote the same elements having the same functions without redundant description. The engine 1 according to the present embodiment is a well-known multi-cylinder internal combustion engine mounted as a power source on a vehicle (not shown). The engine 1 includes a belt cover 2, a sealing material 3, an engine body 9, a timing belt 91, a crankshaft pulley 92, and a camshaft pulley 93. The belt cover 2 has a cover recess 4. The sealing material 3 has a sealing projection 5. The engine body 9 includes a cylinder block, a cylinder head, and the like.

[0017] In the following description, the X-axis direction, the Y-axis direction, and the Z-axis direction are referred to. Each of the X-axis direction, the Y-axis direction, and the Z-axis direction is orthogonal to the other axis directions. The X-axis direction is the direction (in the present embodiment, the horizontal direction) away from the engine body 9 and toward the timing belt 91. The Y-axis direction is the direction (horizontal direction) toward the right in FIG. 2. The Z-axis direction is the direction toward the vertically upward.

[0018] As shown in FIG. 1, the timing belt 91 is wound around the crankshaft pulley 92 and the camshaft pulley 93 and transmits torque from the crankshaft pulley 92 to the camshaft pulley 93. The crankshaft pulley 92 is disposed on the side portion (side surface) of the engine body 9 and is connected to the crankshaft (not shown) of the engine 1 so as to be torque-transmissible. The camshaft pulley 93 is disposed on the side portion of the engine body 9 and is connected to the camshaft (not shown) of the engine 1 so as to be torque-transmissible.

[0019] The belt cover 2 is fixed to the engine body 9 with the sealing material 3 interposed therebetween. As a result, an "internal space" that covers the timing belt 91 is formed by the engine body 9, the belt cover 2, and the sealing material 3. The belt cover 2 is a resin cover member. The sealing material 3 is a rubber sealing member (gasket). The sealing material 3 has an annular shape along the outer peripheral portion of the belt cover 2 and is sandwiched between the outer peripheral portion of the belt cover 2 and the side surface of the engine body 9.

[0020] More specifically, the belt cover 2 is provided with flanges 21a to 21f, which have bolt holes formed therein. Similarly, the sealing material 3 is provided with flanges 31a to 31f, which have bolt holes formed therein. The engine body 9 has tapped bolt holes 94a to 94f formed therein. The belt cover 2 and the sealing material 3 are fixed to the engine body 9 by six bolts 22 (see Figures 2, 8, etc.) that pass through the bolt holes in flanges 21a to 21f and flanges 31a to 31f and are screwed into the bolt holes 94a to 94f. The flange 21a extending vertically downward from the belt cover 2 is also referred to as the "lower flange" for convenience.

[0021] A retaining groove 23 is formed on the back side (seal material 3 side) of the belt cover 2 in a roughly annular continuous shape (see Figures 3 and 6). The retaining groove 23 is omitted in the section that overlaps with the seal protrusion 5. A retaining rib 32 is formed on the front side (belt cover 2 side) of the seal material 3, facing the retaining groove 23 (see Figures 4 and 5, etc.). When the belt cover 2 and seal material 3 are fixed to the engine body 9, the retaining rib 32 is fitted into the retaining groove 23 (see Figure 9).

[0022] On the back side of the seal material 3 (the side facing the engine body 9), a nearly annular continuous sealing rib 33 (bead portion) is formed (see Figures 6, 7, etc.). The sealing rib 33 is omitted on the back side of the sealing protrusion 5 and in its vicinity. When the seal material 3 is fixed to the engine body 9 together with the belt cover 2, the sealing rib 33 comes into contact with and is compressed against the engine body 9, causing it to deform (see Figure 9).

[0023] Incidentally, for example, condensation can cause water (water droplets) to form in the internal space. Therefore, a "drainage passage" is formed in the lower part of the internal space to discharge the water from the internal space. To form the drainage passage, a seal projection 5 is provided in the lower region (lower part) of the seal material 3 (see Figures 4, 5, etc.). The seal projection 5 extends in the direction toward the belt cover 2, away from the engine body 9 (i.e., in the X-axis direction).

[0024] On the other hand, the belt cover 2 (specifically, the flange 21a extending downward from the bottom of the belt cover 2) is provided with a cover recess 4 facing the seal projection 5 (see Figures 3, 6, etc.). That is, the cover recess 4 is included in the flange 21a at the bottom of the belt cover 2. The width w1 of the cover recess 4 (see Figure 3) is approximately equal to the width w2 of the seal projection 5 (see Figure 4). More specifically, the width w1 is slightly longer than the width w2.

[0025] The upper surface 51 (upward-facing surface) of the seal protrusion 5 faces the upper surface 41 (downward-facing surface) of the cover recess 4 and is spaced approximately 1 to 2 mm apart from the upper surface 41 of the recess (see Figure 8). The upper surface 41 of the recess is continuous with the upper surface (the surface forming the inside of the retaining groove 23) that forms the retaining groove 23 at the lower part of the belt cover 2 (see Figure 3).

[0026] The side surface 52 (vertical surface) of the protrusion 5 on the belt cover 2 side (X-axis direction) faces the side surface 42 (vertical surface) of the recess 4 of the cover recess 4 and is spaced approximately 1 to 2 mm apart from the side surface 42 (see Figure 8). The lower surface 53 (downward-facing surface) of the protrusion 5 faces the recess receiving surface 43 (upward-facing surface, lower surface) of the cover recess 4 and is spaced approximately 1 to 2 mm apart from the recess receiving surface 43. The recess receiving surface 43 is also a substantially horizontal surface provided at the boundary (step) between the thin-walled portion of the flange 21a and the thick-walled portion below the thin-walled portion (see Figures 3, 6, etc.).

[0027] The recessed receiving surface 43 extends approximately horizontally from below the lower surface 53 of the protrusion in the direction of the Y-axis (beyond the side of the lower surface 53 of the protrusion (seal protrusion 5)). On the other hand, the recessed receiving surface 43 extends upward in the direction opposite to the Y-axis. Therefore, the recessed receiving surface 43, whose side is shown as a solid line in Figure 3, extends to the upper right to the right of the cover recess 4.

[0028] Therefore, a drainage channel is formed between the seal protrusion 5 and the cover recess 4, extending from the gap between the upper surface 51 of the protrusion and the upper surface 41 of the recess, through the gap between the side surface 52 of the protrusion and the side surface 42 of the recess, to the gap between the lower surface 53 of the protrusion and the receiving surface 43 of the recess (see the arrow in Figure 8).

[0029] Let's explain the drainage channel in more detail. The upper surface 51 of the seal protrusion 5 is recessed downwards (compared to the surface in the vicinity of the upper surface 51 that faces upwards) in order to introduce water into the drainage channel (see Figure 10). Therefore, water adhering to the back surface 24, which is the back surface of the belt cover 2, moves (falls) to the upper surface 51 of the protrusion at the bottom of the back surface 24 (i.e., the lower end of the internal space) (see the arrow in Figure 10).

[0030] Subsequently, the water that has passed through the drainage channel and reached the recessed receiving surface 43 moves along the recessed receiving surface 43 toward the engine body 9 (in the opposite direction to the X-axis) and falls downward from the edge of the recessed receiving surface 43 (see Figure 10). In other words, the water moves downward (falls) through the space formed between the engine body 9 and the flange 21a.

[0031] (modified version) Modifications of this embodiment will be described with reference to Figures 11 and 12. This modification includes a sealing material 3a. The sealing material 3a has a flow channel wall 34 that extends in the Y-axis direction from the flange 31a.

[0032] The surface of the lower part (lower region) of the flow path wall 34 on the belt cover 2 side (X-axis direction side) is in contact with the surface of the thick-walled portion of the flange 21a on the sealing material 3a side (engine body 9 side) (see Figure 12). Therefore, water that reaches the recessed receiving surface 43 via the drainage passage cannot move across the recessed receiving surface 43 toward the engine body 9 side and fall. On the other hand, since the surface of the thin-walled portion of the flange 21a is on the X-axis direction side of the recessed receiving surface 43, the movement of water on the recessed receiving surface 43 in the X-axis direction is restricted.

[0033] Therefore, water that reaches the recessed receiving surface 43 moves along the recessed receiving surface 43 in the Y-axis direction, reaches the edge (on the Y-axis side), and then falls (see the arrow in Figure 11). Alternatively, water that reaches the recessed receiving surface 43 may move along the recessed receiving surface 43 in the opposite direction to the Y-axis direction (uphill) due to vibrations of the vehicle on which the engine 1 is mounted, reaches the edge, and then falls.

[0034] In other words, in this modified example, the drainage passage is extended so that water that reaches the recessed receiving surface 43 (more specifically, the lower side of the seal projection 5) moves in the direction of the Y-axis or the direction opposite to the Y-axis. The extended section of the drainage passage is formed by the recessed receiving surface 43, the flow path wall 34, and the surface of the flange 21a that faces the flow path wall 34 across the recessed receiving surface 43. This extended section can also be described as a path that moves the water that reaches the recessed receiving surface 43 in the direction away from the engine body 9 (the X-axis direction in this embodiment) and in a direction that is substantially perpendicular to it in a top view (the Y-axis direction in this embodiment, or the direction opposite to the Y-axis direction).

[0035] As explained above, the drainage channel formed by the cover recess 4 and the seal protrusion 5, and including multiple bending points, allows water to be discharged from the internal space, while making it extremely difficult for water to enter the internal space by flowing backward through the drainage channel. In other words, the possibility of water kicked up by the tires of the vehicle on which the engine 1 is mounted, as well as foreign matter such as sand and dust, entering the internal space is extremely low.

[0036] In addition, since the drainage passage is formed by the opposing cover recess 4 and seal protrusion 5, it can be realized by simply modifying the shape of the belt cover 2 and the seal material 3. In particular, the cover recess 4 can be formed in the existing flange 21a, which has bolt holes for fixing the belt cover 2 together with the seal material 3 to the engine body 9. That is, the amount of work required to provide a drainage passage in the lower part of the internal space is avoided.

[0037] Furthermore, since the bolts 22 are inserted through bolt holes formed in flanges 21a and 31a (i.e., near the cover recess 4 and seal protrusion 5) and fastened to bolt holes 94a, the assembly of the drainage passage to the engine body is stabilized. As a result, the possibility of deformation of the drainage passage due to vibrations of the vehicle on which the engine 1 is mounted is reduced. In addition, the bolts 22 fastened to bolt holes 94a make the path from the outside to the drainage passage more complex, and therefore contribute to making it more difficult for foreign matter to enter the internal space.

[0038] Furthermore, with the modified sealing material 3a described above, the water discharge path from the inside of the internal space, including the drainage channel, to the outside becomes more complex. Consequently, the possibility of water (or other foreign matter) entering the internal space is further reduced.

[0039] Although embodiments of the present invention have been described above with reference to the above-described structure, it will be apparent to those skilled in the art that many substitutions, improvements, and modifications are possible without departing from the purpose of the present invention. Accordingly, embodiments of the present invention may include all substitutions, improvements, and modifications that do not depart from the spirit and purpose of the appended claims. Embodiments of the present invention are not limited to the above-described special structure, and modifications such as the following are possible.

[0040] As shown in Figure 8, the upper surface 51 and the side surface 52 of the seal protrusion 5 formed a right-angle corner. That is, the angle between the upper surface 51 and the side surface 52 was approximately a right angle. Similarly, the side surface 52 and the lower surface 53 of the protrusion formed a right-angle corner. Alternatively, these corners may be chamfered, either by cutting or rounding the corners. Furthermore, part or all of the upper surface 51, the side surface 52, and the lower surface 53 of the protrusion may be curved surfaces represented as curves (e.g., arcs) in the cross-sectional view shown in Figure 8. Similarly, part or all of the upper surface 41, the side surface 42, and the receiving surface 43 of the recess may be curved surfaces represented as arcs in the cross-sectional view shown in Figure 8. Even in this case, a curved drainage channel can be formed from the top of the seal protrusion 5 through the side (X-axis direction) to the bottom.

[0041] In the modified example described above, the extended section of the drainage channel extended in the Y-axis direction and in the direction opposite to the Y-axis direction (opposite Y-axis direction). Alternatively, the drainage channel may extend in only one of the Y-axis direction and the opposite Y-axis direction. In other words, the recessed receiving surface 43 may extend beyond the side of the sealing projection 5 in only one of the Y-axis direction and the opposite Y-axis direction.

[0042] In the modified example, the side wall of the extended section was formed by the thin-walled portion of the flange 21a and the flow path wall 34 of the sealing material 3a. Alternatively, the side wall of the extended section may be formed by the thin-walled portion of the flange 21a and the surface of the engine body 9. That is, the surface of the engine body 9 may be formed to abut the recessed receiving surface 43 from the side. Or, the belt cover 2 may have a shape similar to the flow path wall 34. That is, the side wall of the drainage channel may be composed of the thin-walled portion of the flange 21a and a newly formed side wall on the belt cover 2.

[0043] The sealing ribs 33, which are arranged on the back side of the sealing material 3, were omitted on the back side of the sealing projection 5 and in its vicinity. Alternatively, the sealing ribs 33 may extend on the back side of the sealing projection 5 and, therefore, be continuous in an annular shape.

[0044] The cover recess 4 and the seal protrusion 5 were formed on flanges 21a and 31a, which had bolt holes. Alternatively, the cover recess 4 and the seal protrusion 5 may be formed on flanges that do not have bolt holes. In other words, a flange for forming a drainage channel may be provided, which is different from the flange with bolt holes used for fixing (fastening) the belt cover 2 and the seal material 3 to the engine body 9.

[0045] The belt cover 2 was a resin cover component. Alternatively, the belt cover 2 may be made of metal. For example, the belt cover 2 may be made of an aluminum alloy formed by die-casting.

[0046] A timing belt 91 (i.e., an endless flexible member) was disposed in the internal space formed by the belt cover 2, the seal material 3, and the engine body 9. Alternatively, a metal timing chain, which transmits torque from the crankshaft to the camshaft of the engine 1, may be disposed in the internal space as an endless flexible member. [Explanation of Symbols]

[0047] 1…Institution 2... Belt cover 3, 3a... Sealing material 4…Cover recess 5...Stick part of the sticker 9...Engine body 21a~21f… Flange 22... Volts 23...Retaining groove 24…Back side 31a~31f…Flange 32…Retaining ribs 33... Ribs for sealing 34...Flow channel wall 41…Upper surface of recess 42…Recessed side 43…Recessed receiving surface 51…Upper surface of the convex part 52... Side view of the convex part 53... Lower surface of the convex part 91... Timing belt 92... Crankshaft pulley 93... Camshaft pulley 94a~94f...Bolt holes

Claims

1. It is an internal combustion engine, A belt cover that covers the timing belt located on the side of the engine body, The belt cover has an annular sealing material that is sandwiched between the outer periphery of the belt cover and the side surface of the engine body, In the region below the sealing material, A seal projection is provided that protrudes toward the belt cover, The aforementioned belt cover includes: A cover recess is provided that faces the seal projection and forms a gap between it and the side surface of the seal projection, and that includes the gap and forms a drainage passage for draining water from inside the belt cover. The aforementioned belt cover is It has a receiving surface that faces the lower surface of the seal projection and forms the drainage channel between itself and the lower surface, The aforementioned receiving surface is An internal combustion engine extending beyond at least one side of the aforementioned lower surface.

2. An internal combustion engine according to claim 1, The aforementioned belt cover is It has a lower flange that extends vertically downward, The aforementioned cover recess is An internal combustion engine included in the aforementioned lower flange.

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