JP2009299651A - Cylinder cooling structure for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder cooling structure for an engine satisfactorily cooling a wall part adjacent to a storage chamber of a cylinder arranged obliquely or horizontally. <P>SOLUTION: The cylinder cooling structure for the engine 1 provided with a crank case 40 storing a crankshaft 10 and provided with an oil storage part 41, a cylinder block 50 connected to the crank case and including cylinders 51 of which center axis are arranged obliquely or horizontally, a cylinder head 60 provided on an end part opposite to the crank case of the cylinder block and including a camshaft 67 opening and closing valves, and the storage chamber 52 provided at a side part of the cylinder and storing a timing chain 70 provided over the crankshaft and the camshaft, includes an oil passage 100 extending substantially along an axial direction of the cylinder, having a section shape provided with a hollow part with a lower side hollowed, and guiding oil from the cylinder head side to the crank case side, on a wall part adjacent to a cylinder inner surface of the storage chamber. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an engine cylinder cooling structure for cooling a cylinder wall adjacent to an engine storage chamber in which a cylinder is inclined or horizontally disposed.

  For example, in an air-cooled engine widely used for a general-purpose engine or the like, the engine is cooled mainly by heat exchange between the cooling fins formed on the cylinder and the cylinder head and the outside air. It has been known that at locations where it is difficult to obtain an effect, the engine oil for lubrication circulated in the engine absorbs heat so as to achieve cooling.

For example, Patent Document 1 describes that an oil passage through which oil that lubricates a valve operating mechanism flows is provided in a peripheral region of an exhaust port that tends to be high temperature inside the cylinder head, thereby improving cooling of the exhaust port. Yes.
Further, Patent Document 2 discloses a fin protruding from the wall of the chain chamber constituting the outer wall of the engine to the indoor side in order to cool the oil returning to the oil reservoir of the crankcase through the chain chamber after lubricating the cylinder head. Is described.
JP-A-11-81954 JP 2006-170145 A

  As in Patent Document 2, in the case of an OHC engine in which a camshaft is provided in a cylinder head and driven by a timing chain, a chain chamber that is a space for accommodating the timing chain is provided in a side portion of the cylinder. The cylinder adjacent to the chain chamber is difficult to cool by outside air using cooling fins. Here, when a part of the cylinder becomes hotter than the other part, the roundness is lost due to a difference in thermal expansion, and when the friction is increased or severe, it may be galvanized and may cause seizure due to oil film breakage. For this reason, normally, oil returning from the cylinder head to the crankcase is caused to flow down along the wall surface of the chain chamber on the cylinder side to cool the oil in the cylinder.

However, in the case of an engine in which the cylinder is arranged upright, there is no problem with the cooling method described above. However, in the case of an engine in which the cylinder is inclined or arranged horizontally, oil is introduced into the chain chamber. However, since oil flows through the lower end of the chain chamber, there is a problem that the cylinder cannot be cooled sufficiently. In particular, when the exhaust port opens upward, it is necessary to cool the upper wall surface of the chain chamber, but when the oil flows through the lower end of the chain chamber, the cooling effect by the oil is almost obtained on the upper side. I can't.
An object of the present invention is to provide an engine cylinder cooling structure that satisfactorily cools a wall portion adjacent to a chain chamber in an inclined or horizontally disposed cylinder.

The present invention solves the above-described problems by the following means.
The invention of claim 1 includes a crankcase that houses a crankshaft and is provided with an oil reservoir, a cylinder block that has a cylinder that is connected to the crankcase and has a central axis that is inclined or disposed horizontally, and the cylinder A cylinder head having a camshaft that is provided at an end opposite to the crankcase in the block and has a camshaft for opening and closing a valve, provided at a side of the cylinder, and provided at the crankshaft and the camshaft. In a cylinder cooling structure for an engine including a storage chamber for storing a timing chain, a wall portion adjacent to the cylinder inner surface of the storage chamber is formed to extend substantially along the axial direction of the cylinder and to be recessed downward. And has a cross-sectional shape provided with a concave portion, and the crankke from the cylinder head side. A cylinder cooling structure of an engine and having an oil passage that guides the oil to the scan side.

According to a second aspect of the present invention, there is provided a crankcase that accommodates a crankshaft and is provided with an oil reservoir, a cylinder block that is connected to the crankcase and is provided with a cylinder that accommodates a piston, and the crank in the cylinder block A cylinder head provided at an end opposite to the case and having a camshaft for opening and closing a valve; and a timing transmission mechanism for transmitting the rotational force of the crankshaft to the camshaft; Has a storage chamber that communicates with the cylinder head and the crankcase at the side of the cylinder, and stores the timing transmission mechanism, and the axial direction of the cylinder is horizontal or inclined with respect to the vertical direction. In the engine cylinder cooling structure configured as described above, adjacent to the cylinder in the storage chamber An oil passage is formed between the wall portion and the rib by providing a rib in the portion that protrudes from the wall portion and extends from the cylinder head side to the crankcase side. It is a structure.
According to a sixth aspect of the present invention, there is provided a crankcase that houses a crankshaft and is provided with an oil reservoir, a cylinder block that is connected to the crankcase and is provided with a cylinder that houses a piston, and the crank in the cylinder block A cylinder head provided at an end opposite to the case and having a camshaft for opening and closing a valve; and a timing transmission mechanism for transmitting the rotational force of the crankshaft to the camshaft; Has a storage chamber that communicates with the cylinder head and the crankcase at the side of the cylinder, and stores the timing transmission mechanism, and the axial direction of the cylinder is horizontal or inclined with respect to the vertical direction. In the engine cylinder cooling structure configured as described above, adjacent to the cylinder in the storage chamber The parts, recesses on the lower side, a cylinder cooling structure of the engine, wherein the oil passage extending from the cylinder head side to the crank case side is formed.

According to the present invention, the following effects can be obtained.
(1) The wall portion adjacent to the cylinder inner surface of the storage chamber has a cross-sectional shape that extends substantially along the axial direction of the cylinder and is provided with a recess formed by being recessed in the lower side. By having an oil passage that guides oil from the crankcase to the crankcase, the oil flow does not collect at the lower end of the storage chamber, and the location adjacent to the cylinder portion in the wall of the storage chamber is good. Can be cooled to. Thereby, it is possible to suppress the temperature of the cylinder portion from becoming nonuniform and to secure the roundness of the cylinder.

(2) Since the oil passage is formed by the rib formed to protrude from the wall portion of the storage chamber, in addition to the effect of (1) described above, the heat transmitted from the wall portion and oil to the rib from the surface of the rib. Since it is released into the air in the storage chamber, the cooling effect can be improved. That is, the rib functions as a cooling fin.
(3) Since the oil passage is formed by recessing the wall portion of the storage chamber, in addition to the effect of (1) described above, the wall portion can be cooled by flowing oil into the oil passage.

  An object of the present invention is to provide a cylinder cooling structure for an engine that satisfactorily cools a wall portion adjacent to a storage chamber in a tilted or horizontally disposed cylinder, and extends from the cylinder side wall portion of the storage chamber. The problem was solved by providing a plurality of ribs which are formed to protrude and are arranged at positions where the protruding end portion is higher than the base portion on the wall side, and the cylinder is cooled by oil flowing through the upper surface portion of the rib.

A first embodiment of an engine cylinder cooling structure to which the present invention is applied will be described below.
FIG. 1 is a cross-sectional view of an engine provided with Embodiment 1 of an engine cylinder cooling structure to which the present invention is applied. FIG. 1 is a cross-sectional view taken along a plane including the central axis of the cylinder and orthogonal to the central axis of the crankshaft.
2 is a cross-sectional view taken along the line II-II in FIG.
3 is a cross-sectional view taken along the line III-III in FIG.

  The engine 1 is, for example, an OHC 4-stroke general-purpose single cylinder air-cooled engine. Engine 1 includes crankshaft 10, piston 20, connecting rod 30, crankcase 40, cylinder block 50, cylinder 51, cylinder head 60, timing chain 70, muffler 81, fuel tank 82, cooling fan 83, shroud 84, starter 85, An air cleaner 86, a storage chamber oil passage 100, and the like are provided.

The crankshaft 10 is a shaft portion that converts the reciprocating motion of the piston 20 into a rotational motion. The crankshaft 10 is rotatably supported on the crankcase 40 by a pair of bearings. The crankshaft 10 includes a crankpin, a counterweight, and the like to which the large end of the connecting rod 30 is connected.
A crank sprocket 11 for driving the timing chain 70 is fixed to the crankshaft 10.

The piston 20 is inserted into the cylinder 51 and reciprocates. The piston 20 has a crown surface facing the cylinder head 60 and receiving combustion pressure. Further, the piston 20 includes a piston ring that ensures airtightness with the inner peripheral surface of the cylinder 51, an oil ring that scrapes off oil, a piston pin to which the small end of the connecting rod 30 is connected, and the like.
The connecting rod 30 is swingably connected to the crankpin of the crankshaft 10 and the piston pin of the piston 20.
Further, a scraper 31 is provided at the large end (crank pin side end) of the connecting rod 30 to splash the oil stored in the oil storage part 41 of the crankcase 40 when the crankshaft 10 rotates.

  The crankcase 40 is a part that houses the crankshaft 10. An oil storage portion 41 for storing lubricating oil is formed at the bottom of the crankcase 40.

The cylinder block 50 includes a cylinder 51, a storage chamber 52, a cooling fin 53, and the like.
The lower end of the cylinder block 50 is connected to the upper part of the crankcase 40.
The cylinder 51 is a substantially cylindrical member into which the piston 20 is inserted on the inner diameter side, and is exposed to high-temperature combustion gas when the engine 1 is operated. For example, the center axis of the cylinder 51 is disposed so as to be inclined with respect to the vertical direction (vertical direction).
As shown in FIGS. 2, 3, etc., the storage chamber 52 is a portion through which the timing chain 70 passes, and is provided on the side of the cylinder 51. The storage chamber 52 is a hollow portion formed through the cylinder block 50 from the crankcase 40 side to the cylinder head 60 side.
The cooling fins 53 cool the cylinder block 50 through heat exchange with air, and are formed to protrude from the outer wall of the cylinder block 50.

  The cylinder head 60 is provided at the upper end of the cylinder block 50 (the end opposite to the crankcase 40). The cylinder head 60 constitutes a combustion chamber of the engine 1 in cooperation with the crown portion of the piston 20 and the cylinder 51. The cylinder head 60 includes an intake port 61, an exhaust port 62, an intake valve 63, an exhaust valve 64, an intake rocker arm 65, an exhaust rocker arm 66, a cam shaft 67, a cam sprocket 68, an ignition plug 69, and the like.

The intake port 61 is a flow path for introducing an air-fuel mixture into the combustion chamber, and is attached to the lower surface portion of the cylinder head 60.
The exhaust port 62 is a flow path for discharging the burned gas from the combustion chamber, and is provided on the upper side of the cylinder head 60 and opens on the upper surface of the cylinder head 60.
The intake valve 63 and the exhaust valve 64 are valves that open and close the intake port 61 and the exhaust port 62 at predetermined valve timings, respectively. Each of the intake valve 63 and the exhaust valve 64 includes a cap-shaped valve body that closes each port, and a stem that is inserted into the cylinder head 60.
The intake rocker arm 65 and the exhaust rocker arm 66 are valve driving force transmission members that are swingably supported with respect to the cylinder head 60. The intake rocker arm 65 and the exhaust rocker arm 66 press the stem upper ends of the intake valve 63 and the exhaust valve 64, respectively.
The camshaft 67 drives the intake valve 63 and the exhaust valve 64 via the intake rocker arm 65 and the exhaust rocker arm 66. A cam sprocket 68 for hanging the timing chain 70 is fixed to the camshaft 67.
The spark plug 69 is supplied with electric power from an ignition control device (not shown) and generates a spark that ignites the air-fuel mixture in the combustion chamber.

The timing chain 70 is provided between the crank sprocket 11 of the crankshaft 10 and the cam sprocket 68 of the cylinder head 60 and transmits the driving force of the camshaft 67. The timing chain 70 is accommodated in an accommodation chamber 52 that communicates with the cylinder head 60 and the crankcase 40.
Further, the timing chain 70 is provided with a tensioner 71 for maintaining the tension within a predetermined range as shown in FIG.
The timing chain 70, the crank sprocket 11 and the cam sprocket 68 constitute a timing transmission mechanism.
In this embodiment, the timing chain is used, but the present invention is not limited to this. For example, a body belt may be used.

The muffler 81 is a silencer that is provided on the top of the cylinder head 60 and connected to the exhaust port 62.
The fuel tank 82 is a container for storing fuel (for example, gasoline) provided in the upper part of the crankcase 40.
The cooling fan 83 is provided at the end opposite to the output portion of the crankshaft 10 and generates cooling air by the rotation of the crankshaft 10.
The shroud 84 is an air guide plate that guides the cooling air generated by the cooling fan 83 to the cooling fins 53 of the cylinder block 50.
The starter 85 is a recoil starter provided at the end of the crankshaft 10 adjacent to the cooling fan 83.
The air cleaner 86 is connected to the intake port 61 and purifies external air sucked into the intake port 61.

Next, the storage chamber oil passage 100 of the storage chamber 52 described above will be described in more detail.
FIG. 4 is a schematic cross-sectional view corresponding to a cross section obtained by cutting the cylinder block 50 along a plane orthogonal to the central axis of the cylinder 51.
The storage chamber oil passage 100 includes, for example, three inclined ribs 101 to 103.
The inclined ribs 101 to 103 are formed to protrude from the wall portion 52 a adjacent to the cylinder 51 of the storage chamber 52 into the storage chamber 52.

As shown in FIG. 3, the inclined ribs 101 to 103 are arranged so as to extend from the connecting portion with the cylinder head 60 to the connecting portion with the crankcase 40 along the axial direction of the cylinder 51. The inclined ribs 101 to 103 are arranged at substantially equal intervals sequentially from above.
As shown in FIG. 4, the inclined ribs 101 to 103 are formed so that the cross-sectional shape viewed along the plane orthogonal to the longitudinal direction is substantially linear. Further, the inclined ribs 101 to 103 are provided so as to be inclined such that the protruding end portion is at a higher position (upward) than the connecting portion with the wall portion 52 a of the storage chamber 52.
Further, a plurality of inclined ribs 101 to 103 are provided in parallel. The lower inclined rib (102) has a larger protruding amount from the wall portion 52a of the storage chamber 52 than the upper inclined rib (for example, 101).
These inclined ribs 101 to 103 are formed by casting at the time of casting the cylinder block 50. However, the inclined ribs 101 to 103 usually extend along the axial direction of the cylinder 51, which is the direction in which the mold is pulled out. Never become.

Next, lubrication and cooling during the operation of the engine 1 will be described. First, lubrication will be described.
The oil stored in the oil storage part 41 of the crankcase 40 is splashed up by the scraper 31 provided on the connecting rod 30 when the crankshaft 10 rotates. The crankshaft 10, the piston 20, the connecting rod 30 and the like are lubricated by being directly exposed to the splashes of oil splashed by the scraper 31.
Part of the oil splash adheres to the timing chain 70 and moves to the cam sprocket 68 side with the timing chain 70. The oil adhering to the timing chain 70 is scattered in the cylinder head 60 by the centrifugal force in the cam sprocket 68 and lubricates the camshaft 67, the rocker arms 65 and 66, the valves 63 and 64, and the like.

  The oil lubricated in the cylinder head 60 flows in the storage chamber 52 by its own weight and returns to the crankcase 40 side. At this time, the oil that has flowed into the inclined ribs 101 to 103 flows in the recesses (grooves) formed between the inclined ribs 101 to 103 and the wall portion 52a. Further, when oil overflows from the recessed portion formed by the inclined rib 101, the overflowed oil is collected in a recessed portion (groove portion) formed by the inclined rib 102 on the lower side. Similarly, when oil overflows from the concave portion formed by the inclined rib 102, the overflowed oil is collected in a concave portion (groove portion) formed by the inclined rib 103 on the lower side. Thus, in Example 1, the storage chamber oil passage 100 is a recess (groove) formed between the inclined ribs 101 to 103 and the wall portion 52a.

Next, cooling of the cylinder block 50 of the engine 1 will be described.
The cylinder block 50 is cooled by heat exchange with outside air mainly by cooling fins 53 formed on the outer surface. However, a cooling fin that comes into contact with the outside air cannot be provided in the vicinity of the cylinder 51 in a portion where the storage chamber 52 is formed, and the cylinder 51 cannot be sufficiently cooled. Therefore, in the first embodiment, the wall 52a and the adjacent cylinder 51 are cooled by absorbing the heat of the wall 52a by the oil flowing through the recesses formed by the inclined ribs 101 to 103 of the storage chamber oil passage 100. Yes. The oil that has absorbed the heat returns to the oil reservoir 41 of the crankcase 40 and is cooled by outside air through the wall of the crankcase 40. Further, the inclined ribs 101 to 103 also function as cooling fins that perform heat exchange with the air in the accommodation chamber 52.

According to Example 1 demonstrated above, the following effects can be acquired.
(1) By providing the storage chamber oil passage 100 in the wall portion 52 a adjacent to the cylinder 51 of the storage chamber 52, the oil flow does not collect at the lower end of the storage chamber 52. Thereby, the part adjacent to the cylinder 51 in the wall part 52a of the storage chamber 52 can be cooled favorably. As a result, the temperature of the cylinder 51 is prevented from becoming non-uniform, the roundness of the cylinder 51 is ensured, and an increase in friction due to deformation of the cylinder 51, galling, seizure, or the like can be prevented.
(2) Since the storage chamber oil passage 100 has the inclined ribs 101 to 103 formed so as to protrude from the wall 52a, the inclined ribs 101 to 103 can function as cooling fins. That is, since the heat transferred from the wall 52a and oil to the inclined ribs 101 to 103 is released from the surface of the inclined ribs 101 to 103 to the air in the storage chamber 52, the cooling effect can be improved.
(3) The inclined ribs 101 to 103 of the storage chamber oil passage 100 are configured to be disposed at a position (above) where the protruding end portion is higher than the connecting portion with the wall portion 52a. A concave portion (groove portion) for holding oil can be formed between the upper surface portion and the wall portion 52a, and the oil flow rate can be secured.

Next, a second embodiment of the cylinder cooling structure to which the present invention is applied will be described. In each of the embodiments described below, the same reference numerals are given to portions that are substantially the same as those in the previous embodiment, and the description thereof will be omitted, and differences will be mainly described.
FIG. 5 is a schematic cross-sectional view corresponding to a cross section obtained by cutting the cylinder block 50 along a plane orthogonal to the central axis of the cylinder 51. (The cross section corresponding to FIG. 4 of Example 1 is shown. The same applies to FIGS. 6 and 7.)
The cylinder cooling structure of the second embodiment includes a storage chamber oil passage 200 described below instead of the storage chamber oil passage 100 of the first embodiment.
The storage chamber oil passage 200 includes curved ribs 201 to 203 described below instead of the inclined ribs 101 to 103 in the storage chamber oil passage 100 of the first embodiment.

The curved ribs 201 to 203 are arranged so as to extend from the connecting portion with the cylinder head 60 to the connecting portion with the crankcase 40 along the axial direction of the cylinder 51. The curved ribs 201 to 203 are arranged at substantially equal intervals sequentially from above.
As shown in FIG. 5, the curved ribs 201 to 203 are formed so as to be curved so that the cross-sectional shape viewed along the plane orthogonal to the longitudinal direction is a circular arc with a convex lower side. . Further, the curved ribs 201 to 203 are formed such that the protruding end portion is positioned higher (upward) than the connecting portion with the wall portion 52a of the storage chamber 52.
A plurality of the curved ribs 201 to 203 are provided in parallel. The lower curved rib (for example, 202) has a larger protruding amount from the wall portion 52a of the storage chamber 52 than the upper curved rib (for example, 201).
In the second embodiment, the accommodation chamber oil passage 200 is a concave portion (groove portion) formed by the curved ribs 201 to 203 and the wall portion 52a.
According to the second embodiment described above, in addition to the same effects as those of the first embodiment described above, the rib surface area can be increased if the protrusion height from the wall portion 52a is equal by curving the rib. The heat dissipation effect can be enhanced. Further, by curving the rib, the capacity of the oil passage 200 in the accommodating chamber can be made larger than that in the first embodiment if the protruding height from the wall 52a is equal, and the cooling effect can be enhanced. .

Next, a third embodiment of the cylinder cooling structure to which the present invention is applied will be described.
FIG. 6 is a schematic cross-sectional view corresponding to a cross section obtained by cutting the cylinder block 50 along a plane orthogonal to the central axis of the cylinder 51.
The cylinder cooling structure of the third embodiment includes a storage chamber oil passage 300 described below instead of the storage chamber oil passage 100 of the first embodiment.
The storage chamber oil passage 300 includes bending ribs 301 to 303 described below in place of the inclined ribs 101 to 103 in the storage chamber oil passage 100 of the first embodiment.

The bending ribs 301 to 303 are arranged so as to extend from the connecting portion with the cylinder head 60 to the connecting portion with the crankcase 40 along the axial direction of the cylinder 51. The bending ribs 301 to 303 are arranged at substantially equal intervals sequentially from above.
As shown in FIG. 6, the bent ribs 301 to 303 include flat base portions 301 a to 303 a that protrude in a substantially orthogonal direction from the wall portion 52 a, and upright portions 301 b that protrude upward from the protruding end portions of the base portions 301 a to 303 a. 303b. As a result, the cross-sectional shape obtained by cutting each of the bending ribs 301 to 303 along a plane orthogonal to the longitudinal direction is substantially L-shaped.
A plurality of the bending ribs 301 to 303 are provided in parallel. The lower bent rib (for example, 302) has a larger protruding amount from the wall portion 52a of the storage chamber 52 than the upper bent rib (for example, 301).
In the third embodiment, the accommodation chamber oil passage 300 is a recess (groove) formed by the bent ribs 301 to 303 and the wall 52a.
According to the third embodiment described above, the same effects as those of the first and second embodiments can be obtained.

Next, a fourth embodiment of the cylinder cooling structure to which the present invention is applied will be described.
FIG. 7 is a schematic cross-sectional view corresponding to a cross section obtained by cutting the cylinder along a plane orthogonal to the central axis.
The cylinder cooling structure of the fourth embodiment includes a storage chamber oil passage 400 described below instead of the storage chamber oil passage 100 of the first embodiment.
The storage chamber oil passage 400 includes a groove 401 described below instead of the inclined ribs 101 to 103 in the storage chamber oil passage 100 of the first embodiment.

The groove 401 is disposed so as to extend from the connecting portion with the cylinder head 60 to the connecting portion with the crankcase 40 along the axial direction of the cylinder 51. For example, six grooves 401 are arranged at substantially equal intervals from above.
The groove part 401 is formed by denting the wall part 52a, and is disposed so as to be inclined so that the groove bottom part is lower than the opening part to the wall part 52a.
Also in the fourth embodiment described above, the oil flowing from the cylinder head 60 side to the crankcase 40 side flows through the groove portion 401, whereby the wall portion 52a and the adjacent portion of the cylinder 51 can be cooled.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) The cross-sectional shape of the oil passage may be any shape as long as it forms a recess (groove) that can hold and flow oil.
(2) The direction in which the oil passage extends is not limited to the direction in which the oil passage extends completely in the axial direction of the cylinder, and the oil passage may be inclined with respect to the axial direction of the cylinder. For example, in the case of an engine in which the cylinder axis is arranged in the horizontal direction, the oil can surely flow to the crankcase side by inclining so that the crankcase side is lower than the cylinder head side.
(3) In Embodiments 1 to 3, the rib of the oil passage is formed integrally with the cylinder. However, the present invention is not limited to this, and the rib that forms the oil passage is formed separately from the cylinder and is mounted. Also good. According to this, the ribs can be formed thinner and densely arranged than when casting integrally with the cylinder, and the cooling effect may be improved.

It is sectional drawing of the engine which has Example 1 of the cylinder cooling structure of the engine to which this invention is applied. It is the II-II part arrow sectional drawing of FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. 2 is a schematic cross-sectional view of a cylinder block in the engine of Embodiment 1. FIG. It is typical sectional drawing of the cylinder block in Example 2 of the cylinder cooling structure of the engine to which this invention is applied. It is typical sectional drawing of the cylinder block in Example 3 of the cylinder cooling structure of the engine to which this invention is applied. It is typical sectional drawing of the cylinder block in Example 4 of the cylinder cooling structure of the engine to which this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 10 Crankshaft 11 Crank sprocket 20 Piston 30 Connecting rod 31 Scraper 40 Crankcase 41 Oil storage part 50 Cylinder block 51 Cylinder 52 Storage chamber 52a Wall part 53 Cooling fin 60 Cylinder head 61 Intake port 62 Exhaust port 63 Intake valve 64 Exhaust valve 65 Intake rocker arm 66 Exhaust rocker arm 67 Cam shaft 68 Cam sprocket 70 Timing chain 71 Tensioner 100 Accommodating chamber oil passage 101-103 Inclined rib 200 Accommodating chamber oil passage 201-203 Curved rib 300 Accommodating chamber oil passage 301-303 Bending rib 301a-303a Base portion 301b to 303b Upright portion 400 Storage chamber oil passage 401 Groove portion

Claims (7)

A crankcase that houses the crankshaft and is provided with an oil reservoir;
A cylinder block having a cylinder connected to the crankcase and having a central axis inclined or horizontally disposed;
A cylinder head having a camshaft that is provided at an end of the cylinder block opposite to the crankcase and that drives the valve to open and close;
In a cylinder cooling structure for an engine, comprising: a housing chamber that is provided on a side of the cylinder and that houses a timing chain provided on the crankshaft and the camshaft;
The wall portion adjacent to the cylinder inner surface of the storage chamber has a cross-sectional shape that extends substantially along the axial direction of the cylinder and is provided with a recess formed by being recessed downward, and is on the cylinder head side. An engine cylinder cooling structure comprising an oil passage for guiding the oil from a crankcase to the crankcase side. A crankcase that houses the crankshaft and is provided with an oil reservoir;
A cylinder block connected to the crankcase and provided with a cylinder for accommodating a piston;
A cylinder head having a camshaft that is provided at an end of the cylinder block opposite to the crankcase and that opens and closes a valve;
A timing transmission mechanism that transmits the rotational force of the crankshaft to the camshaft,
The cylinder block has a storage chamber that communicates with the cylinder head and the crankcase at a side portion of the cylinder and stores the timing transmission mechanism.
In the engine cylinder cooling structure configured such that the axial direction of the cylinder is horizontal or inclined with respect to the vertical direction,
An oil passage is formed between the wall portion and the rib by providing a rib that protrudes from the wall portion and extends from the cylinder head side to the crankcase side in the wall portion adjacent to the cylinder in the storage chamber. An engine cylinder cooling structure characterized by that.   The cylinder cooling structure for an engine according to claim 2, wherein the protruding end portion of the rib is positioned above a connection portion with the wall portion.   4. The engine cylinder cooling structure according to claim 2, wherein a plurality of oil passages are formed by forming a plurality of the ribs.   5. The engine cylinder cooling structure according to claim 4, wherein a plurality of the ribs are formed in parallel, and a protruding amount from the wall portion is larger in the lower rib than in the upper rib. A crankcase that houses the crankshaft and is provided with an oil reservoir;
A cylinder block connected to the crankcase and provided with a cylinder for accommodating a piston;
A cylinder head having a camshaft that is provided at an end of the cylinder block opposite to the crankcase and that opens and closes a valve;
A timing transmission mechanism that transmits the rotational force of the crankshaft to the camshaft,
The cylinder block has a storage chamber that communicates with the cylinder head and the crankcase at a side portion of the cylinder and stores the timing transmission mechanism.
In the engine cylinder cooling structure configured such that the axial direction of the cylinder is horizontal or inclined with respect to the vertical direction,
A cylinder cooling structure for an engine, wherein an oil passage that is recessed downward and extends from the cylinder head side to the crankcase side is formed in a wall portion adjacent to the cylinder in the storage chamber.   The engine cylinder cooling structure according to claim 2, wherein the oil passage is inclined so as to descend from the cylinder head side to the crankcase side.

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