JP2019190369A - engine - Google Patents

Abstract

To provide an engine which inhibits oil leakage.SOLUTION: An engine includes: a cylinder head; a cam housing fastened to the cylinder head; a cam shaft which is rotatably supported by the cam housing and to which lubrication oil is supplied; and a head cover fastened to the cam housing. The cam housing has a side wall extending along the cam shaft. An inner surface of the side wall has a recessed area recessed downward in a gravity direction.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an engine.

  For example, an engine is known in which lubricating oil is supplied to a sliding portion such as a camshaft (see, for example, Patent Document 1).

JP 2012-167647 A

  Some engines include a cylinder head, a cam housing fastened to the cylinder head, and a head cover that covers an upper portion of the cam housing. Each of these members is fastened via a seal member, and oil leakage from the engine is suppressed. Here, in the cylinder head, the temperature is relatively high due to the combustion of fuel, but in the cam housing, the temperature is lower than that of the cylinder head because it is away from the combustion chamber. For this reason, a temperature difference arises between a cylinder head and a cam housing. In particular, this temperature difference increases when the engine is switched from a low load state to a high load state in a short period of time. Due to this temperature difference, the thermal expansion difference between the cylinder head and the cam housing increases, and oil may leak from between the cylinder head and the cam housing.

  Accordingly, an object of the present invention is to provide an engine in which oil leakage is suppressed.

  The object is to provide a cylinder head, a cam housing fastened to the cylinder head, a camshaft rotatably supported by the cam housing and supplied with lubricating oil, a head cover fastened to the cam housing, And the cam housing has a side wall extending along the camshaft, and an inner surface of the side wall has a concave region recessed downward in the direction of gravity.

  The lubricating oil supplied to the camshaft becomes high temperature due to combustion of the engine, and is scattered by the rotation of the camshaft and adheres to the inner surface of the side wall of the cam housing. Since the inner surface of the side wall has a recessed area that is recessed downward in the direction of gravity, oil is stored in the recessed area. For this reason, the heat of oil is transmitted to the cam housing, and heat exchange between the oil and the cam housing is promoted. Thereby, the temperature of a cam housing can be raised, the increase in the temperature difference of a cam housing and a cylinder head can be suppressed, and the increase in the thermal expansion difference of both can also be suppressed. As a result, oil leakage can be suppressed from between the cylinder head and the cam housing.

  The cylinder head has a first seal surface that sandwiches a first seal member with the side wall, and the side wall has a second seal surface that sandwiches a second seal member with the head cover. The concave region may be provided at a position closer to the first seal surface than the second seal surface.

  The inner surface of the side wall has an upper region continuous from the concave region to the upper side in the direction of gravity, and the upper region is the first seal surface when viewed from a cross section perpendicular to the direction in which the camshaft extends. It may be located outside the cam housing with respect to a line segment connecting the inner edge of the second seal surface and the inner edge of the second seal surface.

  The inner side surface of the side wall may be continuously continuous from the upper region to the concave region as seen from a cross section perpendicular to the direction in which the camshaft extends.

  The recessed area may extend along the camshaft.

  The side wall may have a rib partially protruding inside the cam housing.

  The side wall may include an intake side sidewall disposed on the intake side and an exhaust side sidewall disposed on the exhaust side, and the rib may be provided on the exhaust side sidewall.

  According to the present invention, an engine in which oil leakage is suppressed can be provided.

FIG. 1 is an explanatory diagram of an engine. FIG. 2A is a top view of the cam housing, and FIG. 2B is a top view of the cylinder head. FIG. 3A is a front view of the cylinder head and the cam housing, and FIG. 3B is a rear view of the chain cover. 4A is a cross-sectional view taken along the line AA of FIG. 2A, and FIG. 5 is a cross-sectional view taken along line BB in FIG. 2A. FIG. 6A is a partial top view of a cam housing according to a modification. 6B is a cross-sectional view taken along the line CC of FIG. 6A.

  FIG. 1 is an explanatory diagram of the engine 1. FIG. 1 shows the X direction, the Y direction, and the Z direction orthogonal to each other. In FIG. 1, the Z direction is parallel to the gravity direction, and the Y direction is parallel to the direction in which the crankshaft 15, the intake side camshaft 53, and the exhaust side camshaft 54 extend. The engine 1 includes a cylinder block 10, a cylinder head 20, a cam housing 30, and a head cover 40. A cylinder head 20 is fastened to the upper part of the cylinder block 10. A cam housing 30 is fastened to the upper part of the cylinder head 20. A head cover 40 is fastened to the upper portion of the cam housing 30, and the upper portion of the cam housing 30 is covered with the head cover 40.

  The cylinder block 10 is provided with a plurality of cylinders 12, and each cylinder 12 is arranged in the depth direction in FIG. The piston 11 is accommodated in each cylinder 12 so as to be movable up and down. As the piston 11 moves up and down, the crankshaft 15 rotates. The cylinder 12, the piston 11, and the cylinder head 20 define a combustion chamber CH whose volume is increased or decreased by the vertical movement of the piston 11. An oil pan 16 that stores lubricating oil is fastened to the lower portion of the cylinder block 10. The oil is supplied to each sliding portion in the engine 1 by an oil pump through an oil passage formed in the engine 1, and then recovered by the oil pan 16.

  In the cylinder head 20, the right side wall 23 and the left side wall 24 respectively positioned on the right side and the left side in FIG. 1 extend along the Y direction, which is also the cylinder arrangement direction. An intake port 21 and an exhaust port 22 are opened on the outer side surfaces of the right side wall 23 and the left side wall 24, respectively. Each of the intake pipe 81 and the exhaust pipe 82 is fastened to the right side wall 23 and the left side wall 24 so as to communicate with the intake port 21 and the exhaust port 22. Therefore, the intake pipe 81 and the exhaust pipe 82 communicate with the combustion chamber CH via the intake port 21 and the exhaust port 22, respectively. The cylinder head 20 holds an intake valve and an exhaust valve that open and close the intake port 21 and the exhaust port 22 according to the rotation of the intake camshaft 53 and the exhaust camshaft 54, respectively. The cam shafts 53 and 54 are rotatably supported by the cam housing 30.

  FIG. 2A is a top view of the cam housing 30. The cam housing 30 includes a right side wall 33 and a left side wall 34, a rear side wall 35, and a plurality of support walls 37. The rear side wall 35 extends in the X direction continuously to the right side wall 33 and the left side wall 34, and is located at the end of the cam housing 30 in the −Y direction. The plurality of support walls 37 are supported by the right side wall 33 and the left side wall 34 facing each other, and each extend in the X direction. The support wall 37 supports the camshafts 53 and 54 so as to be rotatable at a predetermined interval in the X direction. The camshafts 53 and 54 are respectively formed with an intake cam 53c and an exhaust cam 54c that drive the intake valve and the exhaust valve of each cylinder.

  An intake side sprocket 55 and an exhaust side sprocket 56 are connected to one end of each of the camshafts 53 and 54 on the + Y direction side. A timing chain 65 that links the crankshaft 15 and the sprockets 55 and 56 is wound around the sprockets 55 and 56. As a result, when the crankshaft 15 rotates, the sprockets 55 and 56 also rotate through the timing chain 65. A chain cover 60 that houses the timing chain 65 is fastened to the + Y direction side ends of the cam housing 30 and the cylinder head 20. The illustration of the chain cover 60 is simplified.

  The camshafts 53 and 54 are supplied with lubricating oil stored in the oil pan 16 via a plurality of paths. For example, between the journal bearing provided on the support wall 37 and rotatably holding the camshafts 53 and 54 and the camshafts 53 and 54, oil is provided via an oil passage formed in the camshafts 53 and 54. Is supplied. Oil is supplied from the cam shower to the intake cam 53c and the exhaust cam 54c.

  Sealing surfaces 33 s, 34 s, and 35 s are formed on the upper portions of the right side wall 33, the left side wall 34, and the rear side wall 35, respectively. The sealing surfaces 33s, 34s, and 35s are continuous with each other and are substantially parallel to the XY plane. FIG. 2A shows the seal member CL3 on the seal surfaces 33s, 34s, and 35s. The seal member CL3 is a rubber gasket having oil resistance, and is specifically made of acrylic rubber. However, the seal member CL3 is not limited to this and may be a liquid gasket described later. A plurality of bolt holes into which bolts for fastening the cam housing 30 and the head cover 40 are inserted are formed on the seal surfaces 33 s, 34 s, and 35 s. It is located outside the plurality of bolt holes.

  The cam housing 30 and the head cover 40 are fastened in a state where the seal member CL3 is sandwiched between the seal surfaces 33s, 34s, and 35s and the seal surface of the head cover 40. This prevents a gap from being generated between the cam housing 30 and the head cover 40. The seal surfaces 33 s, 34 s, and 35 s are an example of a second seal surface that sandwiches the seal member CL <b> 3 with the head cover 40. As will be described in detail later, seal surfaces 37s and 38s substantially parallel to the YZ plane are formed on the right side wall 33 and the left side wall 34 on the chain cover 60 side, respectively. The inner side surface of the right side wall 33 and the inner side surface of the left side wall 34 have concave regions 330 and 340, respectively, which will be described in detail later.

  FIG. 2B is a top view of the cylinder head 20. The cylinder head 20 has a rear side wall 25 in addition to the right side wall 23 and the left side wall 24 described above. The rear side wall 25 extends in the X direction continuously to the right side wall 23 and the left side wall 24, and is located at the end of the cylinder head 20 in the −Y direction. The cylinder head 20 includes a holding hole 210 that holds an ignition plug for each cylinder, a guide hole 211 that guides an intake valve, and an exhaust valve that are surrounded by the right side wall 23, the left side wall 24, and the rear side wall 25. A guide hole 212 for guiding is formed. Seal surfaces 23 s, 24 s, and 25 s are formed on the upper portions of the right side wall 23, the left side wall 24, and the rear side wall 25, respectively. The seal surfaces 23s, 24s, and 25s are continuous with each other and substantially parallel to the XY plane.

  FIG. 2B shows the seal member CL2 on the seal surfaces 23s, 24s, and 25s. The seal member CL2 is made of rubber having oil resistance and is also referred to as FIPG (Formed In Place Gasket). FIPG is applied in a liquid state to the seal surfaces 23s, 24s, and 25s of the cylinder head 20 before the cam housing 30 is fastened, and then cured by heating or absorption of moisture in the air to become an elastic body. Liquid gasket. The seal member CL2 is not limited to this, and may be a gasket made of the above-described acrylic rubber or the like. A plurality of bolt holes into which bolts for fastening the cylinder head 20 and the cam housing 30 are inserted are formed on the seal surfaces 23s, 24s, and 25s, and the seal member CL2 It is located outside the plurality of bolt holes. The cylinder head 20 and the cam housing 30 are fastened in a state where the seal member CL2 is sandwiched between the seal surfaces 23s, 24s, and 25s and the seal surface on the −Z direction side of the cam housing 30. This prevents a gap from being generated between the cylinder head 20 and the cam housing 30. The seal surfaces 23s, 24s, and 25s are examples of first seal surfaces that sandwich the seal member CL2 between the right side wall 33, the left side wall 34, and the rear side wall 35, respectively. As will be described later, seal surfaces 27s and 28s substantially parallel to the YZ plane are formed on the right side wall 23 and the left side wall 24 on the chain cover 60 side, respectively.

  FIG. 3A is a front view of the cylinder head 20 and the cam housing 30. FIG. 3A shows a lower side wall 29 of the cylinder head 20 extending in the X direction between the right side wall 23 and the left side wall 24. The sealing surface 29s on the + Y direction side of the lower side wall 29 is continuous with the sealing surfaces 27s and 28s described above, and the sealing surfaces 27s, 28s, and 29s are substantially parallel to the XZ plane. Further, in a state where the cylinder head 20 and the cam housing 30 are fastened, the seal surfaces 27s and 28s of the cylinder head 20 and the seal surfaces 37s and 38s of the cam housing 30 are continuous, and these seal surfaces 27s, 28s, 29s. , 37s, and 38s are substantially parallel in the XZ plane. FIG. 3A shows the seal member CL5 on the seal surfaces 27s, 28s, 29s, 37s, and 38s. The seal member CL5 is a member similar to the seal member CL2 described above, but is not limited thereto.

  FIG. 3B is a rear view of the chain cover 60. FIG. 3B shows a view of a part of the chain cover 60 viewed from the + Y direction. The chain cover 60 has a sealing surface 68s that sandwiches the sealing member CL5 between the sealing surfaces 27s, 28s, 29s, 37s, and 38s. The seal surfaces 27 s, 28 s, 29 s, 37 s, and 38 s and the seal surface 68 s are not labeled, but bolts for fastening the cylinder head 20, the cam housing 30, and the chain cover 60 are inserted. A plurality of bolt holes are formed, and the seal member CL5 is located outside the plurality of bolt holes. The cylinder head 20, the cam housing 30, and the chain cover 60 are fastened with the seal member CL5 sandwiched between the seal surfaces 27s, 28s, 29s, 37s, and 38s and the seal surface 68s. This prevents a gap from being generated between the cylinder head 20 and the cam housing 30 and the chain cover 60.

  As described above, the cylinder head 20 and the cam housing 30 are sealed, the cam housing 30 and the head cover 40 are sealed, and the cylinder head 20 and the cam housing 30 and the chain cover 60 are sealed. The lubricating oil supplied to 53 and 54 is prevented from leaking outside.

  Next, the right side wall 33 of the cam housing 30 shown in FIG. 2A will be described. 4A is a cross-sectional view taken along the line AA in FIG. 2A. This cross section is perpendicular to the direction in which the camshafts 53 and 54 extend. The right wall 33 has a recessed area 330, a curved area 331, and a straight area 332. The curved region 331 continues from the concave region 330 to the upper side in the gravity direction, and the straight region 332 continues from the curved region 331 to the upper side in the gravity direction. The curved region 331 and the straight region 332 are an example of an upper region continuous from the concave region 330 to the upper side in the direction of gravity. The concave region 330 and the curved region 331 are both curved, and the radius of curvature is substantially the same. The inner side surface of the right side wall 33 is curved so as to gradually approach the vertical direction from the concave region 330 to the curved region 331. The straight region 332 is slightly inclined with respect to the direction of gravity in a sectional view, but extends in a substantially linear shape.

  The recessed area 330 is recessed downward in the direction of gravity. FIG. 4B is an enlarged view of the recessed area 330. FIG. 4B shows a horizontal line segment HL parallel to the X direction. Here, the lubricating oil supplied to the camshafts 53 and 54 is scattered by the rotation of the camshafts 53 and 54. At least a part of the scattered oil adheres to the straight region 332 and the curved region 331 on the inner surface of the right side wall 33, flows downward in the direction of gravity, and is stored in the concave region 330. Therefore, the time in which the right side wall 33 is in contact with the oil is secured until the oil overflows from the recessed area 330. Further, the newly scattered oil is always stored in the recessed area 330.

  Here, although oil is supplied to the camshafts 53 and 54 from a plurality of paths, the oil becomes high temperature due to combustion in the engine 1 while the oil is circulating through such paths. For this reason, by storing such high-temperature oil in the concave region 330, the heat of the oil is transmitted to the right side wall 33 of the cam housing 30, and heat exchange between the oil and the cam housing 30 is promoted. Further, since the recessed region 330 is formed to extend in the X direction in which the camshafts 53 and 54 extend, a contact area between the inner side surface of the right side wall 33 of the cam housing 30 and the oil is secured, and the oil and Heat exchange with the cam housing 30 is promoted. FIG. 4A shows the scattered oil.

  In this way, heat exchange between the hot oil and the cam housing 30 is promoted, so that the temperature of the cam housing 30 rises. Thereby, the increase in the temperature difference between the cylinder head 20 and the cam housing 30 can be suppressed, and the increase in the difference in thermal expansion between the cylinder head 20 and the cam housing 30 due to this temperature difference is suppressed. Here, when the difference in thermal expansion between the cylinder head 20 and the cam housing 30 increases, the relative position shifts between the seal surfaces 23 s, 24 s, and 25 s of the cylinder head 20 and the seal surface of the cam housing 30 facing the cylinder head 20. there is a possibility. As a result, the seal member CL <b> 2 interposed between the seal surfaces may be damaged, and oil may leak from between the cylinder head 20 and the cam housing 30. In this embodiment, since the increase in the thermal expansion difference is suppressed as described above, such oil leakage is suppressed.

  As shown in FIG. 4A, the recessed area 330 is formed at a position closer to the seal surface 23s than to the seal surface 33s. The temperature of the cam housing 30 can be increased around the seal surface 23s of the cylinder head 20 that can be a gap through which oil leaks, and the seal surface of the cam housing 30 that faces the seal surface 23s. Thereby, oil leakage can be suppressed suitably.

  Incidentally, the periphery of the seal surface 33s of the cam housing 30 and the seal surface of the head cover 40 facing the cam housing 30 is different from the seal surface of the cam housing 30 facing the seal surface 23s of the cylinder head 20, and is separated from the cylinder head 20. ing. For this reason, in this periphery, the temperature difference and thermal expansion difference between the cam housing 30 and the head cover 40 hardly increase, and oil leakage hardly occurs. Therefore, in this embodiment, the recessed area 330 is formed in the vicinity of the seal surface 23s of the cylinder head 20 where oil leakage is likely to occur.

  FIG. 4A shows a line segment CL connecting the inner edge of the seal surface 23s and the inner edge of the seal surface 33s. The curved region 331 and the straight region 332 are located outside the cam housing 30 with respect to the line segment CL. In other words, the curved region 331 and the straight region 332 protrude outside the cam housing 30 from the line segment CL. For this reason, the length of the inner side surface of the right side wall 33 is ensured compared with the case where the side wall is linear along the line segment CL in a sectional view. Here, as described above, when the scattered oil adheres to the curved region 331 and the straight region 332, it flows to the concave region 330 side. In addition, the time during which oil is attached to the straight region 332 is secured. Therefore, heat exchange between the oil and the right side wall 33 of the cam housing 30 is also promoted by such a configuration. Note that the curved region 331 and the straight region 332 also extend along the camshaft 53, similarly to the recessed region 330.

  As shown in FIG. 4A, the straight region 332 continues smoothly from the curved region 331 to the concave region 330. Thereby, the oil adhering to the straight region 332 or the curved region 331 can be flowed to the concave region 330 at an early stage. For this reason, the oil is stored in the concave region 330 before the straight region 332 or the curved region 331 of the right side wall 33 is deprived of a large amount of oil, and much of the heat of the oil is transmitted to the concave region 330. Thereby, the temperature of the cam housing 30 can be raised around the seal surface 23s of the cylinder head 20 and the seal surface of the cam housing 30 facing the seal surface 23s. Thereby, oil leakage can be suppressed suitably.

  Further, as shown in FIG. 4A, the inclination angle of the straight area 332 located on the upper side in the gravitational direction from the concave area 330 is steeper than the inclination angle at an arbitrary point on the concave area 330. In other words, the inclination angle of the straight region 332 is approximately 90 degrees with respect to the horizontal direction. For this reason, the oil adhering to the straight region 332 can flow to the concave region 330 at an early stage. Also by this, oil leakage can be suppressed suitably.

  5 is a cross-sectional view taken along line BB in FIG. 2A. The left side wall 34 is formed substantially symmetrically with the right side wall 33 on the YZ plane. Accordingly, the inner side surface of the left side wall 34 also has a concave region 340, a curved region 341, and a straight region 342, as with the right side wall 33. For this reason, heat exchange between the left side wall 34 of the cam housing 30 and the oil is also promoted, and oil leakage from the seal surface 24s of the cylinder head 20 and the seal surface of the left side wall 34 of the cam housing 30 is also suppressed. The

  As described above, since an increase in the thermal expansion difference due to the temperature difference between the cylinder head 20 and the cam housing 30 is suppressed, the gap between the seal surfaces 37s and 38s of the cam housing 30 and the seal surface 68s of the chain cover 60 is suppressed. Oil leakage is also suppressed. Further, the heat exchange between the oil and the cam housing 30 suppresses an excessive temperature rise of the oil. As a result, deterioration of the oil and excessive reduction in the viscosity of the oil and the reduction in lubricity are suppressed.

  Moreover, since the surface area of each inner side surface of the right side wall 33 and the left side wall 34 is ensured, the area of the surface where the blow-by gas generated in the engine 1 contacts is also ensured. For this reason, blow-by gas contacts each inner side surface of the right side wall 33 and the left side wall 34, and separation of oil from blow-by gas is promoted. Therefore, increase in oil consumption and generation of white smoke due to blow-by gas being sucked into the intake system are suppressed.

  In this embodiment, the rear side wall 35 is different from the right side wall 33 and the left side wall 34, but the rear side wall 35 may be configured in the same manner. Accordingly, heat exchange with oil can be performed in substantially the entire cam housing 30, and an increase in temperature difference between the cam housing 30 and the cylinder head 20 can be further suppressed.

  In the present embodiment, the recessed area 330 is formed over substantially the entire area in the Y direction, which is the longitudinal direction of the right side wall 33, but is not limited thereto. For example, the above-described recessed region 330 may be formed only in a part of the region in the Y direction of the right side wall 33. For example, such a recessed region 330 may be formed at a position closer to the chain cover 60 than the rear side wall 35. This is because oil leakage from between the cam housing 30 and the chain cover 60 can be suitably suppressed by increasing the temperature of the right side wall 33 of the cam housing 30 near the chain cover 60. The same applies to the recessed region 340 of the left side wall 34.

  Next, a cam housing 30a which is a modified example will be described. FIG. 6A is a partial top view of a modified cam housing 30a. 6B is a cross-sectional view taken along the line CC of FIG. 6A. In the cam housing 30a, a rib 347 is formed on the inner surface of the left side wall 34a. The rib 347 extends downward in the gravitational direction along the inner surface of the left side wall 34a, and protrudes inside the cam housing 30a. The rib 347 is provided between the adjacent support walls 37. By providing the ribs 347 in this manner, the area of the inner side surface of the left side wall 34a is increased. That is, the amount of oil attached to the inner surface of the left side wall 34a is ensured. Thereby, the heat transfer of oil to the left side wall 34a is promoted, and oil leakage is suppressed.

  Further, since the rib 347 is provided on the left side wall 34a, the volume of the left side wall 34a is increased and the rigidity is ensured. Here, by ensuring the rigidity of the left side wall 34a on the exhaust side, vibration of the left side wall 34a due to combustion in the engine is suppressed. For this reason, it is suppressed that the vibration of the left side wall 34a is transmitted to the head cover 40 and the vibration sound is generated.

  The position of the rib 347 is not limited to the position shown in FIG. 6A, but may be provided at a position away from the position where the cylinder head 20 and the cam housing 30a are fastened by bolts. The reason is as follows. In the vicinity of the bolt, an increase in the difference in thermal expansion between the cylinder head 20 and the cam housing 30a can be regulated to some extent by the fastening force of the bolt, whereas such a fastening force does not sufficiently reach the position away from the bolt. there is a possibility. Therefore, by providing the rib 347 at a position away from the bolt, the surface area of the left side wall 34a of the cam housing 30a at a position away from the bolt can be secured, and the cylinder head 20 and the cam housing 30a at a position away from the bolt. This is because it is possible to suppress an increase in the difference in thermal expansion.

  A rib similar to the rib 347 may be provided on the right side wall 33 on the intake side. Thereby, oil leakage can be suppressed more. Further, vibration of the right side wall 33 can also be suppressed. However, by providing such ribs, the weight of the housing may increase and fuel consumption may deteriorate. Therefore, it is desirable to set the position, size, and number of ribs in consideration of the increase in the weight of the housing, the effect of suppressing oil leakage, the effect of reducing vibrations, and the like. For example, vibration due to engine combustion is more easily transmitted to the left side wall 34a on the exhaust side than the right side wall 33 on the intake side. For this reason, in this modification, the rib 347 is provided only on the left side wall 34a from the viewpoint of reducing the vibration of the left side wall 34a on the exhaust side while suppressing an increase in the weight of the cam housing 30a.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

  In the embodiment and the modified example, the concave region 330 is continuously and smoothly continuous with the curved region 331, but is not limited to such a shape. The concave region may be, for example, a region where the inner surface of the side wall is formed in a groove shape on a region near the horizontal direction when viewed from a cross section perpendicular to the direction in which the camshaft extends. In addition, the inner side surface of the side wall is curved so that the inclination angle gradually approaches the horizontal direction from the upper side to the lower side in the direction of gravity, and the inner end of the housing in this curved region goes to the inside of the housing. The recessed area may be defined by a shape protruding upward in the direction of gravity so as to block the oil flow. In the above-described embodiments and modifications, the substantially straight straight region 332 is formed, but the present invention is not limited to this, and may be a curved shape.

1 Engine 20 Cylinder head 23 Right side wall 23s Seal surface (first seal surface)
24 Left side wall 30, 30a Cam housing 33 Right side wall 33s Seal surface (second seal surface)
330 concave region 331 curved region (upper region)
332 Straight area (upper area)
34 Left side wall 347 Rib 53, 54 Camshaft CL2 Seal member (first seal member)
CL3 seal member (second seal member)

Claims (7)

A cylinder head;
A cam housing fastened to the cylinder head;
A camshaft rotatably supported by the cam housing and supplied with lubricating oil;
A head cover fastened to the cam housing,
The cam housing has side walls extending along the camshaft;
The engine, wherein the inner side surface of the side wall has a recessed area that is recessed downward in the direction of gravity. The cylinder head has a first seal surface sandwiching a first seal member between the side wall,
The side wall has a second seal surface sandwiching a second seal member with the head cover,
The engine according to claim 1, wherein the concave region is provided at a position closer to the first seal surface than to the second seal surface. The inner side surface of the side wall has an upper region continuous from the concave region to the upper side in the direction of gravity,
The upper region is located outside the cam housing with respect to a line segment connecting the inner edge of the first seal surface and the inner edge of the second seal surface when viewed from a cross section perpendicular to the direction in which the camshaft extends. The engine of claim 2.   The engine according to claim 3, wherein an inner surface of the side wall is smoothly continuous from the upper region to the concave region when viewed from a cross section perpendicular to a direction in which the camshaft extends.   The engine according to any one of claims 1 to 4, wherein the concave region extends along the camshaft.   The engine according to any one of claims 1 to 5, wherein the side wall includes a rib partially protruding inside the cam housing. The side wall includes an intake side sidewall disposed on the intake side and an exhaust side sidewall disposed on the exhaust side,
The engine according to claim 6, wherein the rib is provided on a side wall on the exhaust side.

Images