JP2024101699A - Internal combustion engine - Google Patents

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

The present invention relates to an internal combustion engine. For example, the present invention relates to an internal combustion engine in which a water drainage passage is formed in the lower part of a belt cover that covers a timing belt provided on the side of the engine body.

Some internal combustion engines have a timing belt that transmits torque from the crankshaft to the camshaft, which is located on the outside (side) of the engine body. When such an internal combustion engine is mounted on a vehicle, foreign matter such as sand, dust, and water kicked up by the vehicle's tires adheres to the timing belt, accelerating the deterioration of the timing belt. For this reason, in many cases, a timing belt cover that covers the timing belt is attached to the engine body, thereby preventing foreign matter from entering the space (internal space) formed between the timing belt cover and the engine body.

On the other hand, if water occurs in the internal space due to condensation, or if water enters the internal space through a gap between the timing belt cover and the engine body, it is necessary to drain the water to the outside. For this reason, in one conventional internal combustion engine, a water drainage structure is formed at the bottom of the timing belt cover. Specifically, a labyrinth-shaped water drainage path (water drainage passage) including multiple bends is formed by a seal material inserted between the timing belt cover and the engine body, as well as water drainage holes and a baffle plate formed in the timing belt cover. This water drainage passage makes it difficult for foreign objects to enter the internal space, while making it possible to drain water from the internal space (see, for example, Patent Document 1).

Specification of Utility Model Registration No. 2529170

However, in order to form the above-mentioned drainage passage, it is necessary to provide the timing belt cover with drainage holes and a baffle plate, etc. This may result in an excessive amount of work being required to manufacture the timing belt cover (including design changes).

The present invention was devised in light of these points, and aims to provide an internal combustion engine that has a water drainage passage for draining water from the internal space of the timing belt cover and that can avoid excessive manufacturing labor.

In order to solve the above problems, the internal combustion engine according to the first aspect of the present invention has a belt cover that covers a timing belt provided on the side of the engine body, and an annular seal material that is sandwiched between the outer periphery of the belt cover and the side of the engine body. A seal protrusion that protrudes toward the belt cover is provided in the lower region of the seal material. The belt cover is provided with a cover recess that faces the seal protrusion and forms a gap between the side of the seal protrusion, and includes the gap and forms a water drainage path for draining water inside the belt cover.

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

The third invention of the present invention is an internal combustion engine according to the first or second invention, in which the belt cover has a receiving surface that faces the lower surface of the seal protrusion and forms the water drainage path between the receiving surface and the lower surface.

The fourth aspect of the present invention is the internal combustion engine according to the third aspect, in which the receiving surface extends beyond at least one side of the lower surface.

The gap formed between the seal protrusion and the cover recess forms a drainage path that includes multiple bending points. Therefore, according to the first invention, while it is possible to drain water from the internal space, it is extremely difficult for water (and other foreign matter) to reverse through the drainage path and enter the internal space. In addition, because the drainage path is formed by the seal protrusion and the cover recess, it is possible to configure the drainage path by simply changing the shape of the belt cover and the seal material, and excessive labor hours are avoided for providing the drainage path.

In the second invention, water that has passed through the gap (uneven path) between the seal protrusion and the cover recess moves (falls) downward 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 water 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.

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 sides of the seal convex portion and the cover concave portion is temporarily blocked by the receiving surface. In other words, the receiving surface forms a bending point of the water drainage portion. Therefore, according to the third invention, it becomes even more difficult for water to enter the internal space.

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 seal protrusion before falling from the receiving surface. In other words, the path of water passing through the water drainage passage becomes more complicated. Therefore, according to the fourth invention, it becomes even more difficult for water to enter the internal space.

1 is an 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 seal member. FIG. 4 is a front view of the lower part of the belt cover and the sealing material. FIG. 4 is a rear view of the lower part of the belt cover. FIG. 4 is a front view of the lower part of the sealing material. 13 is an exploded perspective view of a convex portion of a sealing material that constitutes a water drainage passage and a belt cover that covers the convex portion. FIG. 13 is an exploded perspective view of a recess in the belt cover that constitutes a water drainage path and a seal material that covers the recess. FIG. FIG. 2 is a cross-sectional view of the lower portion of an undeformed seal material. 4 is a cross-sectional view including a belt cover fixed to an internal combustion engine and a convex portion and a concave portion at a lower portion of a sealing material. FIG. FIG. 2 is a cross-sectional view excluding the convex and concave portions of the lower portion of the belt cover and the sealing material fixed to the internal combustion engine. FIG. 11 is a perspective view showing the path of water flowing through the water drainage passage. FIG. 11 is a perspective view taken from the same perspective as FIG. 10 , showing the path of water flowing through a water drainage passage in a modified example of the present embodiment. 9 is a cross-sectional view showing a cross section similar to that of FIG. 8, including a convex portion and a concave portion at the bottom of a belt cover and a sealing material according to this modified example.

An embodiment of the present invention will be described with reference to Figures 1 to 10. The same symbols (reference numbers) in the description refer to the same elements having the same functions, although they will not be described repeatedly. The engine 1 according to this embodiment is a well-known multi-cylinder internal combustion engine mounted on a vehicle (not shown) as a driving force source. The engine 1 includes a belt cover 2, a seal material 3, an engine body 9, a timing belt 91, a crankshaft pulley 92, and a camshaft pulley 93. The belt cover 2 includes a cover recess 4. The seal material 3 includes a seal protrusion 5. The engine body 9 includes a cylinder block, a cylinder head, etc.

In the following description, the X-axis direction, the Y-axis direction, and the Z-axis direction will be referred to. Each of the X-axis direction, the Y-axis direction, and the Z-axis direction is perpendicular to the other axes. The X-axis direction is a direction away from the engine body 9 toward the timing belt 91 (in this embodiment, a horizontal direction). The Y-axis direction is a direction toward the right in FIG. 2 (horizontal direction). The Z-axis direction is a direction toward the vertically upward direction.

As shown in FIG. 1, the timing belt 91 is wound around a crankshaft pulley 92 and a 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 (side surface) of the engine body 9, and is connected to the crankshaft (not shown) of the engine 1 so as to be capable of transmitting torque. The camshaft pulley 93 is disposed on the side of the engine body 9, and is connected to the camshaft (not shown) of the engine 1 so as to be capable of transmitting torque.

The belt cover 2 is fixed to the engine body 9 with the sealing material 3 sandwiched between them. 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 that fits along the outer periphery of the belt cover 2, and is sandwiched between the outer periphery of the belt cover 2 and the side of the engine body 9.

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

A roughly annular continuous retaining groove 23 is formed on the back side (sealing material 3 side) of the belt cover 2 (see Figs. 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 3, facing the retaining groove 23 (see Figs. 4, 5, etc.). When the belt cover 2 and the seal 3 are fixed to the engine body 9, the retaining rib 32 is fitted into the retaining groove 23 (see Fig. 9).

A sealing rib 33 (bead portion) is formed in a generally annular shape on the back side (engine body 9 side) of the sealing material 3 (see Figures 6, 7, etc.). The sealing rib 33 is omitted on the back side of the sealing protrusion 5 and its vicinity. When the sealing material 3 is fixed to the engine body 9 together with the belt cover 2, the sealing rib 33 comes into contact with the engine body 9 and is compressed and deformed (see Figure 9).

However, for example, water (water droplets) may occur in the internal space due to condensation. For this reason, a "drainage passage" for draining water from the internal space is formed in the lower part of the internal space. In order to form the drainage passage, a seal protrusion 5 is provided in the lower region (lower part) of the seal material 3 (see Figures 4 and 5, etc.). The seal protrusion 5 protrudes (extends) away from the engine body 9 in a direction toward the belt cover 2 (i.e., in the X-axis direction).

On the other hand, the belt cover 2 (specifically, the flange 21a extending downward from the lower portion of the belt cover 2) has a cover recess 4 facing the seal protrusion 5 (see Figures 3, 6, etc.). That is, the cover recess 4 is included in the flange 21a at the lower portion 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 protrusion 5 (see Figure 4). More specifically, the width w1 is slightly longer than the width w2.

The upper surface 51 (the surface facing upward) of the seal protrusion 5 faces the upper surface 41 (the surface facing downward) of the recess 4 of the cover recess 4 and is spaced about 1 to 2 mm from the upper surface 41 (see FIG. 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 bottom of the belt cover 2 (see FIG. 3).

The convex side surface 52 (vertical surface) of the seal convex portion 5 on the belt cover 2 side (X-axis direction side) faces the recess side surface 42 (vertical surface) of the cover recess 4 and is spaced about 1 to 2 mm from the recess side surface 42 (see Figure 8). The convex lower surface 53 (downward facing surface) of the seal convex portion 5 faces the recess receiving surface 43 (upward facing surface, lower surface) of the cover recess 4 and is spaced about 1 to 2 mm 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 portion of the flange 21a and the thick portion located below the thin portion (see Figures 3, 6, etc.).

The recess receiving surface 43 extends substantially horizontally from below the protruding portion underside 53 in the Y-axis direction (past the side of the protruding portion underside 53 (seal protruding portion 5)). On the other hand, the recess receiving surface 43 extends upward in the opposite direction to the Y-axis direction. Therefore, the recess receiving surface 43, the side of which is shown as a solid line in Figure 3, extends upward to the upper right, to the right of the cover recess 4.

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

The water drainage passage will now be described in more detail. The upper surface 51 of the seal protrusion 5 is recessed downward (relative to the surface facing upward near the upper surface 51) in order to introduce water into the water drainage passage (see FIG. 10). Therefore, water that adheres to the back surface 24, which is the rear 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 bottom end of the internal space) (see the arrow in FIG. 10).

Then, the water that passes through the drainage passage and reaches the recessed receiving surface 43 moves on the recessed receiving surface 43 toward the engine body 9 (in the direction opposite to the X-axis) and falls downward from the edge of the recessed receiving surface 43 (see Figure 10). That is, the water moves downward (falls) through the space formed between the engine body 9 and the flange 21a.

(Modification)
A modification of this embodiment will be described with reference to Figures 11 and 12. This modification includes a seal 3a. The seal 3a includes a flow path wall 34 that extends in the Y-axis direction from a flange 31a.

The surface of the lower part (lower region) of the flow path wall 34 on the belt cover 2 side (X-axis direction side) abuts against the surface of the seal material 3a side (engine body 9 side) of the thick part of the flange 21a (see FIG. 12). Therefore, water that reaches the recess receiving surface 43 through the water drainage path cannot move on the recess receiving surface 43 to the engine body 9 side and fall. On the other hand, since the surface of the thin part of the flange 21a is on the X-axis direction side of the recess receiving surface 43, the movement of water on the recess receiving surface 43 in the X-axis direction is restricted.

Therefore, water that reaches the recess receiving surface 43 moves on the recess receiving surface 43 in the Y-axis direction, reaches the edge (on the Y-axis side), and then falls (see the arrow in FIG. 11). Alternatively, water that reaches the recess receiving surface 43 may move on the recess 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.

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

As explained above, the drainage passage 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 reverse through the drainage passage and enter the internal space. In other words, the possibility of water stirred up by the tires of the vehicle on which the engine 1 is mounted, as well as foreign objects such as sand and dust, entering the internal space is extremely low.

In addition, since the drainage passage is formed by the cover recess 4 and the seal protrusion 5 facing each other, it can be realized by simply changing 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 in which bolt holes are formed for fixing the belt cover 2 together with the seal material 3 to the engine body 9. In other words, it is possible to avoid an excessive amount of work required to provide a drainage passage at the bottom of the internal space.

Furthermore, the bolts 22 are inserted into bolt holes formed in the flanges 21a and 31a (i.e., near the cover recess 4 and the seal protrusion 5) and fastened to the bolt holes 94a, so that the water drainage passage can be stably attached to the engine body. This reduces the possibility that the water drainage passage will be deformed due to vibrations of the vehicle on which the engine 1 is mounted. In addition, the bolts 22 fastened to the bolt holes 94a make the path from the outside to the water drainage passage more complicated, which can contribute to making it more difficult for foreign objects to enter the internal space.

Furthermore, with the sealing material 3a according to the above-mentioned modified example, the water drainage path from the inside of the internal space to the outside, including the water drainage passage, becomes more complex. Therefore, the possibility of water (or other foreign matter) entering the internal space is further reduced.

Although the embodiment of the present invention has been described above with reference to the above structure, it will be apparent to those skilled in the art that many alternatives, improvements, and modifications are possible without departing from the scope of the present invention. Accordingly, the present invention may include all alternatives, improvements, and modifications that do not depart from the spirit and scope of the appended claims. The present invention is not limited to the specific structure described above, and may be modified, for example, as follows:

The convex upper surface 51 and the convex side surface 52 of the seal convex portion 5 shown in FIG. 8 formed a right-angled corner. That is, the angle between the convex upper surface 51 and the convex side surface 52 was approximately a right angle. Similarly, the convex side surface 52 and the convex lower surface 53 formed a right-angled corner. Alternatively, these corners may be chamfered to remove the corners or round the corners. Furthermore, a part or all of the convex upper surface 51, the convex side surface 52, and the convex lower surface 53 may be curved surfaces represented as curved lines (e.g., arcs) in the cross-sectional view shown in FIG. 8. Similarly, a part or all of the recess upper surface 41, the recess side surface 42, and the recess receiving surface 43 may be curved surfaces represented as arcs in the cross-sectional view shown in FIG. 8. Even in this case, a bent (curved) water drainage path may be formed from the upper side of the seal convex portion 5 to the lower side via the side (X-axis direction side).

The extension section of the drainage passage in the above-mentioned modified example extends in the Y-axis direction and in the opposite direction to the Y-axis direction (opposite direction of the Y-axis). Alternatively, the drainage passage may extend only in one of the Y-axis direction and the opposite direction to the Y-axis. In other words, the recess receiving surface 43 may extend beyond the side of the seal protrusion 5 only in one of the Y-axis direction and the opposite direction to the Y-axis.

The side walls of the extension section in the modified example were formed by the thin portion of the flange 21a and the flow path wall 34 of the sealing material 3a. Alternatively, the side walls of the extension section may be formed by the thin 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 so as to abut the recess receiving surface 43 from the side. Alternatively, the belt cover 2 may have a shape similar to the flow path wall 34. That is, the side walls of the drainage channel may be formed by the thin portion of the flange 21a and a side wall newly formed on the belt cover 2.

The sealing rib 33 arranged on the back side of the sealing material 3 was omitted on the back side of the sealing protrusion 5 and in its vicinity. Alternatively, the sealing rib 33 may extend on the back side of the sealing protrusion 5 as well, and thus may be continuous in an annular shape.

The cover recess 4 and the seal protrusion 5 are formed on the flange 21a and the flange 31a in which the bolt holes are formed. Alternatively, the cover recess 4 and the seal protrusion 5 may be formed on a flange in which no bolt holes are formed. In other words, a flange for forming a water drainage passage may be provided that is different from the flange in which the bolt holes used for fixing (fastening) the belt cover 2 and the seal material 3 to the engine body 9 are formed.

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

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 that transmits torque from the crankshaft of the engine 1 to the camshaft may be disposed in the internal space as an endless flexible member.

1...engine 2...belt cover 3, 3a...sealing material 4...cover recess 5...seal protrusion 9...engine body 21a to 21f...flange 22...bolt 23...retaining groove 24...back surface 31a to 31f...flange 32...retaining rib 33...sealing rib 34...flow path wall 41...recess upper surface 42...recess side surface 43...recess receiving surface 51...protrusion upper surface 52...protrusion side surface 53...protrusion lower surface 91...timing belt 92...crankshaft pulley 93...camshaft pulley 94a to 94f...bolt hole

Claims (4)

1. An internal combustion engine,
A belt cover that covers a timing belt provided on a side of the engine body;
an annular seal material sandwiched between an outer circumferential portion of the belt cover and a side surface of the engine body;
In the lower region of the sealing material,
A seal protrusion protruding toward the belt cover is provided,
The belt cover includes:
an internal combustion engine, comprising: a cover recess that faces the seal protrusion and forms a gap between itself and a side surface of the seal protrusion, the cover recess including the gap and forming a water drainage passage for draining water inside the belt cover. 2. The internal combustion engine according to claim 1,
The belt cover is
A lower flange extending vertically downward is provided.
The cover recess is
An internal combustion engine contained within said lower flange. 3. An internal combustion engine according to claim 1 or 2,
The belt cover is
the internal combustion engine having a receiving surface facing a lower surface of the seal protrusion and defining the water drainage passage between the receiving surface and the lower surface. 4. An internal combustion engine according to claim 3,
The receiving surface is
An internal combustion engine extending beyond at least one side of the lower surface.

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