JP2023032904A - Engine oil passage structure - Google Patents

Abstract

To provide an engine oil passage structure capable of curbing an increase in an oil temperature.SOLUTION: An oil passage structure of an engine 1, for circulating oil stored in an oil pan 30 with an oil pump 31 in a manner that transfers and supplies the same to a lubricated section and returns the same to the oil pan 30, comprises a cylinder head concave section 4A which is installed in the cylinder head 4 and allows oil lubricating a lubricated section to fall into the same in drops. The cylinder head concave section 4A has: a bottom face 4a which is installed on a position including an upper portion of a cooling section 14 cooling the cylinder head 4 and extended in a width direction perpendicular to a crank shaft 6a of an engine body 10; and an inclined face 4c upwardly inclined from an edge section of the bottom face 4a in the width direction to an outside. The inclined face 4c has an inclined wettability change section 60 in which wettability with respect to the oil is changed in a direction from an upper side to a lower side so as to enhance an oil flow. The bottom face 4a has a bottom face wettability change section 70 in which the wettability with respect to the oil is changed in a direction toward the cooling section 14 so as to enhance the oil flow.SELECTED DRAWING: Figure 4

Description

The present invention relates to an oil passage structure for an engine mounted on a vehicle such as an automobile.

Generally, an engine mounted on a vehicle sucks out oil stored in an oil pan provided on the lower side of a cylinder block of the engine by an oil pump, and lubricates parts of the engine (e.g., cylinders, pistons, etc.). , camshaft, etc.).

The oil supplied to the parts to be lubricated such as the camshaft provided in the upper part of the engine is dripped into the cylinder head which is arranged on the upper surface of the cylinder block and forms a combustion chamber together with the piston. It is returned to the oil pan through the oil return passage.

The temperature of the oil supplied to the lubricated portion may rise due to heat received from the lubricated portion depending on the temperature of the lubricated portion. In this case, it is preferable to cool the oil because the viscosity of the oil decreases due to the temperature rise of the oil and the lubricity decreases.

Generally, a cylinder head includes a combustion chamber, an intake port and an exhaust port that open to the combustion chamber, and a water jacket as a cooling portion through which cooling water flows for cooling the combustion chamber. The cylinder head consists of a bottom surface that extends in the width direction (intake side and exhaust side) perpendicular to the crankshaft above the water jacket, and sloped surfaces that slope outward in the width direction from both ends of the bottom surface. A recess is provided. A camshaft or the like is arranged at the upper end of the cylinder head, and oil supplied to a lubricated portion such as the camshaft is dripped onto the bottom surface.

In Patent Document 1, in order to promote cooling of the oil, a plurality of fins protruding upward from the bottom surface are provided on the bottom surface located above the water jacket, so that the oil drips onto the bottom surface and flows along the bottom surface. An internal combustion engine is disclosed that includes a cylinder head structure that facilitates heat exchange between oil and cooling water.

JP 2017-44118 A

When using low-viscosity oil with a lower upper limit temperature than oil with normal viscosity for the purpose of improving fuel efficiency, or when eliminating the oil cooler for the purpose of reducing costs and the number of parts, the temperature rise of the oil itself is minimized. Further suppression is required.

An object of the present invention is to provide an engine oil passage structure capable of suppressing an increase in oil temperature.

The present invention is an engine oil passage structure in which oil stored in an oil pan arranged below a cylinder block of an engine body is transported by an oil pump, supplied to a lubricated part, and then returned to the oil pan for circulation. A cylinder head recess is provided in the cylinder head of the engine body, and drips oil after lubricating the lubricated parts, and the cylinder head recess is a cooling part that cools the cylinder head. a bottom surface provided at a position including an upper portion and extending in a width direction perpendicular to the crankshaft of the engine body; The inclined surface has an inclined surface wettability changing portion that changes the wettability with respect to oil from the top to the bottom to promote the flow of oil, and the bottom surface directs the wettability with respect to oil toward the cooling portion. Provided is an engine oil passage structure having a bottom surface wettability changing portion that promotes the flow of oil by changing the bottom surface wettability.

According to the present invention, the sloped surface wettability changing portion can change the wettability with respect to oil on the sloped surface from the top to the bottom, thereby promoting the flow of the oil. By changing the wettability of the oil so that the lipophilicity increases from the top to the bottom of the inclined surface, the oil moves from the top to the bottom of the inclined surface and the oil reaches the bottom surface on the lower side of the inclined surface. can be guided, and the residence time of the oil on the inclined surface can be reduced.

Even when the cylinder head is warmed by exhaust gas or an exhaust system installed on the outer wall side of the engine body, it is possible to reduce the residence time of the oil passing through the inclined surface and suppress the oil from receiving heat from the engine body. It is possible to reduce the temperature rise of the oil.

In addition, the wettability of the bottom surface to oil can be changed toward the cooling portion by the bottom surface wettability changing portion. By changing the wettability of the oil so that the lipophilicity increases toward the cooling part of the bottom surface, the oil can be moved toward the cooling part and guided to the bottom surface above the cooling part. The residence time of the oil on the bottom surface cooled by the part can be increased.

It is possible to increase the residence time of the oil that is dripped onto the bottom surface and stays on the bottom surface above the cooling section, and promotes the release of the heat of the oil warmed by the frictional heat of the lubricated part to the bottom surface above the cooling section. , the temperature rise of the oil can be suppressed.

The inclined surface wettability changing portion may include a plurality of inclined surface side concave portions formed on the inclined surface such that lipophilicity increases from the side opposite to the bottom surface toward the bottom surface.

With this configuration, a plurality of inclined surface side recesses are formed in the inclined surface in the inclined surface wettability changing portion. It is possible to guide the oil to the bottom surface on the lower side of the inclined surface by increasing it from the opposite bottom surface side to the bottom surface side (from top to bottom) and moving the oil from the top to the bottom of the inclined surface. Retention time of oil can be reduced.

The bottom surface wettability changing portion may include a plurality of bottom surface side concave portions formed on the bottom surface so that lipophilicity increases from the inclined surface side toward the cooling portion side.

With this configuration, since a plurality of bottom-side recesses are formed in the bottom surface of the bottom wettability changing portion, a relatively simple configuration formed by forming a plurality of bottom-side recesses can direct the lipophilicity toward the cooling portion of the bottom surface. The height can be increased to guide the oil toward the bottom surface above the cooling section, and the residence time of the oil on the bottom surface cooled by the cooling section can be increased.

The cylinder head may be made of a metal material, and the plurality of inclined surface side recesses may be formed in the inclined surface so as to be deep from the opposite bottom surface side toward the bottom surface side.

With this configuration, the lipophilicity is directed from the top to the bottom of the inclined surface by the plurality of inclined surface side recesses formed on the inclined surface with a deeper depth from the opposite bottom side to the bottom side (upper to lower) of the inclined surface. can be higher.

The cylinder head may be made of a metal material, and the plurality of inclined surface side recesses may be formed on the inclined surface so as to increase in width from the opposite bottom surface side toward the bottom surface side.

With this configuration, the lipophilicity is directed from the top to the bottom of the inclined surface by the plurality of inclined surface side recesses formed in the inclined surface with a large width from the opposite bottom side to the bottom side (from above to below) of the inclined surface. can be higher.

The cylinder head may be made of a metal material, and the plurality of bottom-side concave portions may be formed on the bottom surface so as to be deep toward the cooling section.

With this configuration, the lipophilicity can be increased toward the upper bottom surface of the cooling unit by the plurality of bottom-side concave portions formed deeper toward the upper bottom surface of the cooling unit.

The cylinder head may be made of a metal material, and the plurality of bottom-side concave portions may be formed on the bottom surface to have a large width toward the cooling section.

With this configuration, the lipophilicity can be increased toward the upper bottom surface of the cooling unit by the plurality of bottom-side concave portions formed to have a larger width toward the upper bottom surface of the cooling unit.

A layer made of a fluororesin material is provided in the cylinder head concave portion, and the plurality of inclined surface side concave portions are formed in the inclined surface so that the depth thereof is shallow from the opposite bottom surface side toward the bottom surface side. good too.

With this configuration, the lipophilicity is increased toward the cooling part of the bottom surface by the plurality of inclined surface side recesses formed on the inclined surface with a shallow depth from the opposite bottom surface side to the bottom surface side (from above to below). can do.

A layer made of a fluororesin material is provided in the cylinder head concave portion,
The plurality of inclined-surface-side concave portions may be formed on the inclined surface so as to increase in width from the opposite bottom surface side toward the bottom surface side.

With this configuration, the lipophilicity can be increased toward the cooling portion of the bottom surface by means of the plurality of inclined surface-side recesses that are formed in the inclined surface so as to increase in width from the upper side to the lower side of the inclined surface.

A layer made of a fluororesin material is provided in the cylinder head concave portion,
The plurality of bottom-side concave portions may be shallowly formed on the bottom surface toward the cooling section.

With this configuration, the lipophilicity can be increased toward the upper bottom surface of the cooling unit by the plurality of bottom-side concave portions formed shallower toward the upper bottom surface of the cooling unit.

A layer made of a fluororesin material is provided in the cylinder head concave portion,
The plurality of bottom-side concave portions may be formed on the bottom surface so as to have a large width toward the cooling portion.

With this configuration, the lipophilicity can be increased toward the upper bottom surface of the cooling unit by the plurality of bottom-side concave portions formed to have a larger width toward the upper bottom surface of the cooling unit.

The engine body is provided with a water jacket for flowing cooling water from a water pump,
The cooling unit may be composed of the water jacket.

With this configuration, since the oil return passage is arranged adjacent to the water jacket, the cooling water flowing through the water jacket can cool the inner peripheral surface of the oil return passage. As a result, the heat dissipation of the oil is promoted, and the temperature rise of the oil can be suppressed.

According to the engine oil passage structure of the present invention, it is possible to suppress the temperature rise of the oil.

1 is a schematic diagram showing the configuration of an engine according to an embodiment of the invention; FIG. FIG. 2 is a cross-sectional view of the cylinder head taken along line II-II in FIG. 1; FIG. 2 is a cross-sectional view of a cylinder block taken along line III-III in FIG. 1; FIG. 3 is a cross-sectional view showing an oil passage of the engine along line IV-IV in FIG. 2; 1 is a schematic diagram showing an oil supply passage of an engine according to an embodiment of the invention; FIG. FIG. 4 is another cross-sectional view showing the oil passage of the engine according to the embodiment of the present invention; FIG. 5 is a schematic cross-sectional view of an exhaust-side slope indicated by arrow VII in FIG. 4; FIG. 4 is an explanatory diagram for explaining wettability to oil; FIG. 5 is a schematic cross-sectional view of the bottom surface indicated by arrow IX in FIG. 4; FIG. 8 is a diagram showing a modification of the exhaust-side inclined surface shown in FIG. 7; FIG. 10 is a view showing a modified example of the bottom surface shown in FIG. 9;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

An oil passage structure according to an embodiment of the present invention is applied to an engine 1. As shown in FIG. As shown in FIG. 1, an engine 1 according to an embodiment of the present invention is a so-called vertical type engine 1 that is mounted on a vehicle such as an automobile and has a crankshaft 6a that extends in the front-rear direction. The engine 1 includes an engine body 10 , and the engine body 10 includes a cylinder block 3 in which cylinders 2 are formed, and a cylinder head 4 arranged on the cylinders 2 . The cylinder block 3 and the cylinder head 4 are made of a metal material such as an aluminum alloy.

A piston 5 is arranged in the cylinder 2 so as to be able to reciprocate. The piston 5 is connected via a connecting rod 7 to a crankshaft 6 rotatably supported at the bottom of the cylinder block 3 , so that the reciprocating motion of the piston 5 is converted into the rotational motion of the crankshaft 6 .

An intake port 15 and an exhaust port 16 are formed in the cylinder head 4 . Each cylinder 2 is provided with two intake ports 15 and an exhaust port 16, and the two intake ports 15 and exhaust ports 16 are provided separately in the axial direction of the crankshaft 6a orthogonal to the central axis 2a of the cylinder 2. ing.

An intake passage (not shown) that supplies air to the combustion chamber 8 is connected to the intake port 15, and an exhaust passage (not shown) that discharges exhaust gas, which is combustion gas, from the combustion chamber 8 is connected to the exhaust port 16. ) is connected. A catalyst device 11 having a catalyst for purifying exhaust gas and an exhaust pipe 12 are connected to the exhaust passage. The catalyst device 11 and the engine 1 are arranged side by side in the width direction of the vehicle body.

Intake valves and exhaust valves for opening and closing the intake port 15 and the exhaust port 16, respectively, are arranged in the upper portion of the cylinder head 4, as indicated by the phantom lines. The intake valve opens and closes the intake port 15 at a predetermined timing by an intake camshaft 17 drivingly connected to the crankshaft 6 to supply air to the combustion chamber 8 during the intake stroke. The exhaust valve opens and closes the exhaust port 16 at a predetermined timing by an exhaust camshaft 18 drivingly connected to the crankshaft 6, and discharges exhaust gas from the combustion chamber 8 during the exhaust stroke.

Inside the cylinder head 4, a head-side water jacket 14 is formed as a cooling portion through which cooling water for cooling the cylinder head 4, particularly the combustion chamber 8, circulates. A head-side water jacket 14 is provided above the combustion chamber 8 and between the intake port 15 and the exhaust port 16 in the cross section shown in FIG. The head-side water jacket 14 is provided above each combustion chamber 8 and is formed to surround a boss portion 51 for attaching a spark plug (not shown). In this embodiment, the spark plug is provided at the center of the cylinder 2 along the central axis 2a of the cylinder 2, so that the central portion of the head-side water jacket 14 in the width direction orthogonal to the crankshaft 6 is aligned with the cylinder. 2 is located in the vicinity of the central axis 2a.

In the cylinder head 4, there is formed a part of an oil passage, which will be described later, and a cylinder head recess into which oil after lubricating the lubricated parts such as the camshafts 17 and 18 provided at the upper end of the cylinder head 4 drops. 4A is provided. The cylinder head recessed portion 4A includes a bottom surface 4a positioned above the head-side water jacket 14 near the center in the vertical direction of the cylinder head 4 and extending in the width direction perpendicular to the crankshaft 6a, and both ends of the bottom surface 4a in the width direction. It has inclined surfaces 4b and 4c that incline upward toward the outside in the width direction.

A center portion in the width direction of the bottom surface 4 a is arranged so as to substantially match the central axis 2 a of the cylinder 2 . Therefore, the widthwise central portion of the bottom surface 4a and the widthwise central portion of the head-side water jacket substantially match in the widthwise direction. The inclined surfaces 4b and 4c include an intake-side inclined surface 4b located on one side in the width direction of the bottom surface 4a and an exhaust-side inclined surface 4c located on the other side in the width direction across the crankshaft 6a.

The exhaust-side inclined surface 4c is inclined upward from the end portion of the bottom surface 4a on the catalyst device 11 side toward the catalyst device 11 side. The exhaust-side inclined surface 4c constitutes a part of the inner surface of the side wall of the cylinder head 4, and is located on the exhaust side, so that the temperature of the exhaust-side inclined surface 4c becomes higher than that of the bottom surface 4a due to the exhaust gas. In addition, since the catalyst device 11 is arranged adjacent to the exhaust-side inclined surface 4c on the widthwise outer side, the exhaust-side inclined surface 4c is likely to be heated to a higher temperature by the exhaust gas of the catalyst device 11 .

On the other hand, since the bottom surface 4a is arranged at a position including the upper side of the head-side water jacket 14, the temperature of the bottom surface 4a is lower than that of the exhaust-side inclined surface 4c. Furthermore, as described above, since the widthwise central portion of the bottom surface 4a substantially coincides with the widthwise central portion of the head-side water jacket 14, the central portion of the bottom surface 4a is located on both sides of the bottom surface 4a in the widthwise direction. It is in a relatively cooled state.

One end side and the other end side of the cylinder head concave portion 4A in the direction of the crankshaft 6a are closed by a front surface portion 4d and a rear surface portion 4e rising from the one end side and the other end side of the crankshaft 6a of the bottom surface 4a (see FIG. 2). ). Concave portions for arranging the intake camshaft 17 and the exhaust camshaft 18 are provided in the front surface portion 4d and the rear surface portion 4e.

As shown in FIG. 2, the cylinder head 4 extends in the cylinder direction and has a rectangular shape in plan view. A boss portion 51 for mounting a spark plug (not shown) for each cylinder 2 is provided on the bottom surface 4a. An intake boss portion 52 and an exhaust boss portion 53 are provided on the bottom surface 4a on the intake side and the exhaust side with the boss portion 51 interposed therebetween, respectively. An intake valve is arranged on the intake boss portion 52 , and an exhaust valve is arranged on the exhaust boss portion 53 .

A plurality of head bolt insertion holes 54a for inserting head bolts (not shown) for attaching the cylinder head 4 to the cylinder block 3 are provided on the bottom surface 4a so as to surround the cylinder 2 for each cylinder. On the bottom surface 4a, head-side return passages 42 and 46, which will be described later, are provided on the side wall of the head bolt insertion hole 54a on the side opposite to the crankshaft.

As shown in FIG. 3 , on the upper side of the cylinder block 3 , a cylinder-side water jacket 13 as a cooling portion through which cooling water flows is provided so as to surround the cylinder 2 radially outwardly of the cylinder 2 . The cylinder-side water jacket 13 has a closed-loop structure surrounding the radially outer side of the cylinders 2 of the cylinder train. The cylinder-side water jacket 13 is formed to open upward.

Portions of the cylinder-side water jacket 13 located on both sides across the axial direction of the crankshaft 6a include a plurality of arcuate portions 13a that partially surround the cylinders 2 and a plurality of recesses 13b that enter between the cylinders 2. have. In the cylinder-side water jacket 13, arc-shaped portions 13a and recessed portions 13b are alternately and continuously arranged on both sides in the axial direction of the cylinder row. A front end portion 13c and a rear end portion 13c, which connect the arcuate portions 13a and surround the front and rear ends of the cylinder 2, are arranged at the front and rear ends of the cylinder row.

A plurality of screw holes 54b into which head bolts for fixing the cylinder head 4 are screwed are provided on both sides of the cylinder block 3 across the row of cylinders. Each screw hole 54b is arranged outside the concave portion 13b, the front end portion 13c, and the rear end portion 13c of the cylinder-side water jacket 13 in plan view.

As shown in FIG. 4, the cylinder block 3 has an upper cylinder block 3a and a lower cylinder block 3b arranged below the upper cylinder block 3a. It is provided in the area above 3a. The cylinder-side water jacket 13 is formed with a depth that extends downward from the upper end of the cylinder block 3 to the vicinity above a main gallery 37a, which will be described later.

In this embodiment, an oil pan 30 for storing oil for lubricating parts to be lubricated such as the piston 5, the crankshaft 6, the camshafts 17 and 18, etc., is arranged at the lower end of the cylinder block lower 3b. .

In this embodiment, as shown in FIG. 1, the engine 1 is mounted on the vehicle body frame in a state in which the central axis 2a of the cylinder 2 extends in a direction inclined by a predetermined angle θ1, such as 10 degrees, from the vertical direction toward the exhaust side. is supported by and mounted on the vehicle.

As shown in FIGS. 1 and 4 to 6, the engine 1 includes an oil passage 20 for circulating oil for lubricating the parts to be lubricated (the piston 5, the crankshaft 6, the camshafts 17 and 18, etc.). is provided. The oil passage 20 has an oil supply passage 21 for supplying oil to the lubricated portion and an oil return passage 22 for returning the oil supplied to the lubricated portion to the oil pan.

As shown in FIG. 5 , the oil supply passage 21 includes an oil pump 31 that sucks up the oil stored in the oil pan 30 , an oil filter 32 that filters the oil discharged from the oil pump 31 , and an oil filter 32 that filters the oil discharged from the oil pump 31 . and an oil cooler 33 for cooling the oil to be supplied, and a supply oil passage 35 provided in the engine body 10. - 特許庁

The supply oil passage 35 includes a first supply oil passage 36 provided on the oil pan 30 side, a second supply oil passage 37 provided in the cylinder block 3, and a third supply oil passage 38 provided in the cylinder head 4. , a first communication oil passage 39 that connects the first supply oil passage 36 and the second supply oil passage 37, and a second communication oil passage 40 that connects the second supply oil passage 37 and the third supply oil passage 38. and

As shown in FIGS. 1 and 5, the oil pump 31 is driven by the crankshaft 6, and the oil discharged from the oil pump 31 flows through the first supply oil passage 36 into the oil filter 32 where it is filtered. After that, it flows into the oil cooler 33 and is cooled. Oil cooled by the oil cooler 33 is supplied to the second supply oil passage 37 of the cylinder block 3 through the first communication oil passage 39 .

As shown in FIGS. 1, 4, and 5, the first supply oil passage 36 includes an oil passage 36a provided in the oil pan 30 and connecting the oil pump 31 and the oil filter 32, and an exhaust gas from the oil pan 30. The oil passage 36b is provided adjacent to the side surface of the cylinder block 3 and connects the oil filter 32 and the oil cooler 33, and the oil passage 36b extends upward from the oil cooler 33 and is connected to the first communication oil passage 39 provided in the cylinder block 3. and 36c.

As shown in FIGS. 4 and 5, the first communication oil passage 39 is provided in the lower cylinder block 3b, opens to the exhaust side, and extends in the radial direction of the cylinder 2 (the width direction of the engine body 10). an oil passage 39b extending upward from a radially inner end of the oil passage 39a to open the cylinder block lower 3b upward; and an oil provided in the cylinder block upper 3a and communicating with the oil passage 39b and extending upward. path 39c.

The second supply oil passage 37 includes a main gallery 37a to which an oil passage 39c is connected and extending in the direction of the row of cylinders, and a main gallery 37a branched from the main gallery 37a and extending downward toward the crankshaft 6a to supply lubrication to the crankshaft 6. and a plurality of branched oil passages 37b for supplying oil to the parts.

The main gallery 37 a is located near the lower end of the cylinder 2 on the exhaust side of the cylinder block 3 in the width direction of the cylinder block 3 perpendicular to the row direction of the cylinders. A downstream end of each of the plurality of branched oil passages 37 b opens toward the crankshaft 6 a of the cylinder block 3 .

As shown in FIGS. 5 and 6, the second supply oil passage 37 further includes an oil passage 37c that branches from one end of the main gallery 37a and extends in the width direction to communicate with the second communication oil passage 40. Prepare.

The second communication oil passage 40 is provided in the cylinder block upper 3a and communicates with the oil passage 40a extending upward from the main gallery 37a side end of the oil passage 37c and the oil passage 40a provided in the cylinder head 4. and an oil passage 40b extending upward.

The third supply oil passage 38 includes an oil passage 38a extending from the upper end of the oil passage 40b to both sides in the width direction, a pair of oil passages 38b extending upward from the exhaust side and the intake side of the oil passage 38a, and a cylinder row extending from the oil passage 38b. and a head-side gallery 38c extending in the direction. The head-side gallery 38c includes a plurality of branched oil passages 38d formed to supply oil from the head-side gallery 38c to the cam journals on the intake side and the exhaust side of the camshafts 17 and 18, respectively.

In addition to the configuration described above, the oil supply passage 21 is formed, for example, so as to supply oil to an oil jet or the like for cooling the piston.

As shown in FIG. 4, the oil supplied to the camshafts 17 and 18, which are the parts to be lubricated of the engine 1, through the oil supply passage 21 is applied to the intake side and exhaust side inclined surfaces 4b and 4c and the bottom surface of the cylinder head 4. 4a (arrow a), and is returned to the oil pan 30 through the head-side return passages 42 and 46 constituting the oil return passage 22 provided in the bottom surface 4a.

When the engine 1 is mounted on the vehicle body, the bottom surface 4a is inclined with respect to the horizontal surface 2b so that the exhaust side is lower than the intake side. Therefore, the oil dropped onto the bottom surface 4a is easily guided to the head-side return passage 42 on the exhaust side.

The oil return passage 22 comprises a plurality of exhaust-side return passages 41 and an intake-side return passage 45 through which the oil supplied to the camshafts 17 and 18, which are lubricated portions, flows divided into the exhaust port 16 side and the intake port 15 side. Prepare. The exhaust-side return passage 41 and the intake-side return passage 45 include head-side return passages 42 and 46 provided in the cylinder head 4 and block-side return passages 43 and 47 provided in the cylinder block 3 . Since the exhaust-side return passage 41 and the intake-side return passage 45 have the same configuration, the exhaust-side return passage 41 will be described.

The head-side return passage 42 is formed in a substantially circular shape in a plan view and extends vertically. A plurality of head-side return passages 42 are provided on the exhaust side of the cylinder head 4 and communicate with the block-side return passages 43 . The head-side return passage 42 is arranged between the cylinders 2 at a position offset from each cylinder 2 in the cylinder row direction.

The block-side return passage 43 is formed in a substantially circular shape in a plan view and extends vertically. The block-side return passage 43 includes upper-side return passages 43a and 43b extending vertically from the upper end to the lower end of the cylinder block upper 3a, and lower-side return passages extending downward from the upper end of the cylinder block lower 3b and opening into the oil pan 30. 43f.

The upper return passages 43a and 43b include an upper return passage 43a positioned above the cylinder block upper 3a and a lower return passage 43b positioned below the cylinder block upper 3a.

The upper return passage 43a is adjacent to the cylinder-side water jacket 13 and provided along the cylinder-side water jacket 13, as shown in FIGS. The upper return passage 43 a extends from the upper end of the cylinder block 3 to near the lower end of the cylinder-side water jacket 13 . The upper return passage 43 a is formed to have approximately the same depth as the cylinder-side water jacket 13 .

The upper return passage 43 a is positioned outside the recess 13 b that enters between the cylinders 2 , between the arc-shaped portions 13 a of the cylinder-side water jacket 13 . The upper return passage 43a is offset between the cylinders 2 in the central axis 2a of each cylinder 2 and in the cylinder row direction.

The lower return passage 43b is adjacent to the outside of the oil passage 39c of the first communication oil passage 39 of the oil supply passage 21 and is provided along the oil passage 39c. The lower return passage 43b extends from the vicinity of the main gallery 37a to the lower end of the cylinder block upper 3a.

The upper return passage 43a and the lower return passage 43b are offset in the width direction position orthogonal to the cylinder row direction, and the lower return passage 43b is arranged closer to the outer wall side of the engine body 10 than the upper return passage 43a. ing. A radial passage 43c is provided between the upper return passage 43a and the lower return passage 43b to allow the upper return passage 43a and the lower return passage 43b to communicate with each other.

The radial passage 43c has a substantially circular shape and extends from the outer wall portion of the cylinder block 3 toward the lower side of the cylinder-side water jacket 13 in a direction perpendicular to the upper return passage 43a and the lower return passage 43b. . The lower end of the upper return passage 43a communicates with the radial passage 43c, and the upper end of the lower return passage 43b communicates with the radial passage 43c. 43c.

The lower side passage 43f extends vertically from the upper end toward the lower end of the cylinder block lower 3b. The lower side passage 43f is formed to communicate with the lower return passage 43b and open to the oil pan 30. As shown in FIG.

When the engine 1 starts operating, the oil pump 31 is driven as the crankshaft 6 rotates. 5, the oil pump 31 sucks the oil stored in the oil pan 30 from the suction port 31a of the oil pump 31, and feeds the sucked oil through the first supply oil passage 36, The lubricant is supplied to the parts to be lubricated in the engine body 10 through the first communication oil passage 39 , the second supply oil passage 37 , the second communication oil passage 40 and the third supply oil passage 38 in order.

The oil supplied to the parts to be lubricated in this way lubricates the parts to be lubricated through the oil supply passage 21, and after absorbing heat such as frictional heat generated during the operation of the parts to be lubricated, flows through the oil return passage 22. is returned to the oil pan 30 via the

Since the oil flowing into the oil return passage 22 is warmed by absorbing heat such as frictional heat generated when the parts to be lubricated operate, the bottom surface 4a provided at a position including the upper side of the head-side water jacket 14, Then, the heat of the oil is radiated through the upper return passage 43 a provided adjacent to the cylinder-side water jacket 13 , so that the oil is cooled and returned to the oil pan 30 .

FIG. 7 is a cross-sectional view of the exhaust-side inclined surface 4c shown in FIG. FIG. 7 shows a schematic cross-sectional view of the exhaust-side inclined surface 4c of the cylinder head 4 according to the embodiment of the present invention. As described above, the exhaust-side inclined surface 4c constitutes a part of the inner surface of the side wall of the engine body 10, and is located on the exhaust side, so that it becomes hotter than the bottom surface 4a due to the exhaust gas. Therefore, the temperature of the oil flowing along the exhaust-side inclined surface 4c to the bottom surface 4a tends to rise due to the heat received from the exhaust-side inclined surface 4c. In contrast, in the present embodiment, the wettability to oil is inclined to the exhaust side so that the lipophilicity increases from the top to the bottom of the exhaust-side inclined surface 4c (from the side opposite to the bottom surface 4a toward the bottom surface 4a). By changing the surface 4c from the top to the bottom, the oil is moved from the top to the bottom of the exhaust-side inclined surface 4c and guided to the bottom surface 4a on the lower side of the exhaust-side inclined surface 4c. The retention time of the oil on the inclined surface 4c is reduced to suppress the temperature rise of the oil on the exhaust-side inclined surface 4c.

As shown in FIGS. 2 and 7, the exhaust-side inclined surface 4c has wettability to oil in the inclination direction of the exhaust-side inclined surface 4c so that the lipophilicity increases from the upper side to the lower side of the exhaust-side inclined surface 4c. A changed wettability changing portion 60 is provided.

The wettability changing portions 60 are formed on the exhaust-side inclined surface 4c so that the oleophilicity increases from above the exhaust-side inclined surface 4c toward below (from the side opposite to the bottom surface 4a to the bottom surface 4a side). A plurality of inclined surface side grooves 61 are provided as recesses. Each of the plurality of inclined surface side groove portions 61 is formed to have a predetermined length L1 extending in the cylinder row direction of the exhaust side inclined surface 4c over the entire vertical direction of the exhaust side inclined surface 4c. The portions 61 are formed separately from above and below the exhaust-side inclined surface 4c. In addition, as shown in FIG. 2, the plurality of inclined surface side grooves 61 may be partially provided, for example, between boss portions provided on the bottom surface 4a.

Each of the plurality of inclined surface side groove portions 61 is formed to have a U-shaped cross section having a predetermined width W1 and a predetermined depth D1. The width W1 of the plurality of inclined surface side grooves 61 is set to be the same, and the depth D1 of the plurality of inclined surface side grooves 61 is set to increase from the upper side to the lower side of the exhaust side inclined surface 4c. .

In this manner, the plurality of inclined surface-side grooves 61 are formed such that the depth D1 increases from the upper side to the lower side of the exhaust-side inclined surface 4c. It is formed so that it becomes high toward the downward direction. In FIG. 7, the inclined surface side groove portion 61 is shown in an enlarged manner for easy viewing, but the inclined surface side groove portion 61 is formed, for example, with a width and depth within the range of 0.1 μm to 0.5 μm. It is a very fine groove. The length of the inclined surface side groove portion 61 in the cylinder row direction is formed within a range of several millimeters to several hundred millimeters.

FIG. 8 is an explanatory diagram for explaining wettability to oil. 8A shows a state in which the oil 100 adheres to the wall surface 101, and FIG. 8B shows a state in which the oil 100 enters the groove 102 provided on the wall surface 101. FIG. In FIG. 8, the width of the groove 102 is W, the depth of the groove 102 is D, the opening area of the groove 102 is a1, and the area of the groove 102 is a2.

When the oil 100 transforms from the state shown in FIG. 8A to the state shown in FIG. 8B and the oil 100 creates a new surface, E1 is the energy required. It can be represented by Esurf×(a2−a1). Here, Esurf indicates the surface free energy of the oil 100.

Also, the energy required when the oil 100 transforms from the state shown in FIG. 8B to the state shown in FIG. E2, the energy E2 can be expressed by the following equation: E2=Einterface×a2. Here, Einterface indicates the interfacial interaction energy of the oil 100 .

The lipophilicity, which is the degree of lipophilicity of the oil 100 with respect to the wall surface 101, can be expressed by (E2-E1). When E1<E2, as shown in FIG. The state of penetrating into 102 is stable (lipophilic), and the greater the difference (E2-E1) between the energy E1 and the energy E2, the higher the lipophilicity. In the case of E1>E2, as shown in FIG. 8A, the state in which the oil 100 adheres to the wall surface 101 is stabilized (oil repellency).

The lipophilicity (E2−E1) is expressed as (Einterface−Esurf)×a2+Esurf×a1. When the groove 102 is formed of a metal material satisfying the following formula: Einterface>Esurf, the depth D of the groove 102 is increased. Then, since the area a2 of the groove portion 102 is increased, the degree of lipophilicity is increased and the lipophilicity is enhanced.

On the other hand, when the groove 102 is made of a fluororesin material that satisfies the following equation: Einterface<Esurf, increasing the depth D of the groove 102 increases the area a2 of the groove 102, thereby lowering the lipophilicity. It becomes less lipophilic and more oil-repellent.

Further, when the width W of the groove portion 102 is increased, the difference between the area a2 of the groove portion 102 and the opening area a1 of the groove portion 102 becomes smaller, and the energy E1 becomes smaller. Also when it is formed by

In the exhaust-side inclined surface 4c shown in FIG. 7, the plurality of grooves 61 are formed so that the depth D1 increases from the upper side to the lower side of the exhaust-side inclined surface 4c. It is formed so that it becomes high toward the downward direction.

In this way, by changing the wettability with oil so that the lipophilicity increases from the top to the bottom of the exhaust-side inclined surface 4c, the oil is moved from the top to the bottom of the exhaust-side inclined surface 4c. Oil can be guided from above the exhaust-side inclined surface 4c to the lower bottom surface 4a, and the retention time of the oil on the exhaust-side inclined surface 4c can be reduced.

Even when the cylinder head 4 on which the exhaust-side inclined surface 4c is formed is warmed by the exhaust gas of the catalytic device 11 in addition to the combustion gas flowing through the exhaust port 16, the amount of oil remaining on the exhaust-side inclined surface 4c is reduced. The residence time can be reduced, the heat received by the oil from the engine body 10 can be suppressed, and the temperature rise of the oil can be reduced.

Since a plurality of inclined surface grooves 61 are formed in the exhaust-side inclined surface 4 c of the inclined surface wettability changing portion 60 , the inclined surface wettability can be improved by a relatively simple structure formed by forming the plurality of inclined surface grooves 61 . A change section 60 can be formed.

FIG. 9 is a cross-sectional view of the bottom surface 4a shown in FIG. FIG. 9 shows a schematic cross-sectional view of the bottom surface 4a of the cylinder head 4 according to the embodiment of the invention. The exhaust-side inclined surface 4c constitutes a part of the inner surface of the side wall of the cylinder head 4, and is located on the exhaust side, so that the temperature of the exhaust-side inclined surface 4c becomes higher than that of the bottom surface 4a due to the exhaust gas. In addition, since the catalyst device 11 is arranged adjacent to the exhaust-side inclined surface 4c on the widthwise outer side, the exhaust-side inclined surface 4c is likely to be heated to a higher temperature by the exhaust gas of the catalyst device 11 . On the other hand, since the bottom surface 4a is arranged at a position including the upper side of the head-side water jacket 14, the temperature of the bottom surface 4a is lower than that of the exhaust-side inclined surface 4c. Furthermore, as described above, since the widthwise central portion of the bottom surface 4a substantially coincides with the widthwise central portion of the head-side water jacket 14, It is in a cooled state compared to Therefore, the central portion in the width direction of the bottom surface 4a has the lowest temperature in the cylinder head concave portion 4A.

Therefore, the oil flowing along the exhaust-side inclined surface 4c to the bottom surface 4a and the oil dropped directly onto the bottom surface 4a from a lubricated portion such as a camshaft are guided to the vicinity of the center of the width direction of the bottom surface 4a, and the head-side water is supplied to the bottom surface 4a. It is preferable to increase the residence time at the bottom surface cooled by the cooling water in jacket 14 . On the other hand, in the present embodiment, the wettability to oil is changed so that the oleophilicity increases from both end portions of the bottom surface 4a in the width direction perpendicular to the cylinder shaft 2a and the crankshaft 6a toward the central portion. Therefore, the oil can be moved from both ends of the bottom surface 4a toward the center, and can be guided to the vicinity of the center of the bottom surface 4a located above the water jacket 14. The residence time of the oil can be increased, the heat dissipation of the oil to the bottom surface 4a is promoted, and the temperature rise of the oil is suppressed.

As shown in FIG. 9, the bottom surface 4a has a wettability with oil so that the oleophilicity increases from both ends of the bottom surface 4a in the width direction perpendicular to the cylinder shaft 2a and the crankshaft 6a toward the vicinity of the central portion. A bottom surface wettability changing portion 70 is provided that is changed toward the central portion in the width direction of 4a.

The bottom surface wettability changing portion 70 has an exhaust side changing portion 70a provided on the exhaust side with the cylinder shaft 2a interposed therebetween, and an intake side changing portion 70b provided on the intake side with the cylinder shaft 2a interposed therebetween. The exhaust-side changing portion 70a has a plurality of bottom-side concave portions formed on the bottom surface 4a such that the lipophilicity increases from the exhaust side of the bottom surface 4a toward the center portion (cylinder shaft 2a) in the width direction of the bottom surface 4a. An exhaust-side groove portion 71a is provided. Each of the plurality of exhaust-side grooves 71a is formed to extend in the cylinder row direction over the entirety of the bottom surface 4a on the exhaust side of the cylinder shaft 2a. are spaced apart from each other. Note that the plurality of exhaust-side grooves 71a may be partially provided, for example, between bosses provided on the bottom surface 4a, as shown in FIG.

Each of the plurality of exhaust-side grooves 71a is formed to have a U-shaped cross section having a predetermined width W2 and a predetermined depth D2. The width W2 of the plurality of exhaust-side grooves 71a is set to be the same, and the depth D2 of the plurality of exhaust-side grooves 71a is set to increase from the exhaust side toward the central portion of the bottom surface 4a.

In this way, the plurality of exhaust-side grooves 71a are formed such that the depth D2 increases from the exhaust side toward the center of the bottom surface 4a. It is formed so that it becomes high. In FIG. 7, the exhaust-side groove portion 71a is shown enlarged for the sake of clarity. It is a minute groove formed within a range of several millimeters to several hundreds of millimeters.

The intake-side changing portion 70b includes a plurality of intake-side grooves as a plurality of bottom-side concave portions formed on the bottom surface 4a such that the lipophilicity increases from the intake side of the bottom surface 4a toward the central portion (cylinder shaft 2a) of the bottom surface 4a. A portion 71b is provided. Each of the plurality of intake side grooves 71b is formed to extend in the cylinder row direction of the bottom surface 4a over the entire intake side of the bottom surface 4a with respect to the cylinder shaft 2a. are spaced apart from each other in the center. Note that the plurality of intake-side grooves 71b may be partially provided, for example, between bosses provided on the bottom surface 4a, as shown in FIG.

Each of the plurality of intake-side grooves 71b is formed to have a U-shaped cross section having a predetermined width W3 and a predetermined depth D3. The width W3 of the plurality of intake-side grooves 71b is set to be the same, and the depth D3 of the plurality of intake-side grooves 71b increases from the intake side toward the central portion (from the intake side to the cooling unit side) of the bottom surface 4a. is set to

In this way, the plurality of intake-side grooves 71b are formed so that the depth D3 increases from the exhaust side toward the center of the bottom surface 4a. It is formed so that it becomes high. In FIG. 9, the intake side groove portion 71b is shown in an enlarged manner for easier viewing, but the intake side groove portion 71b is formed, for example, with a width and depth within the range of 0.1 μm to 0.5 μm and a length of 0.1 μm to 0.5 μm. It is a minute groove formed within a range of several millimeters to several hundreds of millimeters.

In this embodiment, the exhaust-side changing portion 70a and the intake-side changing portion 70b are provided so as to be line-symmetrical with respect to the cylinder shaft 2a. The exhaust-side changing portion 70a has an exhaust-side groove 71a formed deeper from the exhaust side toward the central portion of the bottom surface 4a. Since they are formed deep, the bottom surfaces of the plurality of exhaust-side grooves 71a and the plurality of intake-side grooves 71b are generally V-shaped in cross section perpendicular to the cylinder shaft 2a.

In the portion of the bottom surface 4a on the exhaust side of the cylinder shaft 2a shown in FIG. , the lipophilicity is formed so as to increase from the exhaust side of the bottom surface 4a toward the central portion side.

In this way, by changing the wettability to the oil so that the lipophilicity increases from the exhaust side toward the central portion of the bottom surface 4a, warm oil dripping from the exhaust-side inclined surface 4c and the camshaft is removed. , the oil can be moved from the exhaust side of the bottom surface 4a toward the central portion side to guide the oil to the vicinity of the central portion of the bottom surface 4a located above the water jacket 14, and the vicinity of the central portion where the temperature is the lowest in the bottom surface 4a. can increase the residence time of the oil in the

In addition, by changing the wettability with oil so that the oleophilicity increases from the intake side toward the central portion of the bottom surface 4a, even on the intake side of the bottom surface 4a, the oil drips from the intake-side inclined surface 4b and the camshaft. The warmed oil can be moved from the intake side toward the central portion of the bottom surface 4a and guided to the vicinity of the center portion in the width direction of the bottom surface 4a located above the water jacket 14. The residence time of the oil can be increased in the vicinity of the central portion in the width direction where the temperature is the lowest.

By providing the intake-side changing portion 70b in addition to the exhaust-side changing portion 70a, it is possible to suppress further movement of the oil, which has been moved toward the widthwise central portion of the bottom surface 4a by the exhaust-side changing portion 70a, toward the intake side. , it is easy to further increase the retention time of the oil in the vicinity of the central portion of the bottom surface 4a located above the water jacket 14 and cooled by the cooling water.

FIG. 10 is a sectional view showing a modification of the exhaust-side inclined surface 4c shown in FIG. The exhaust-side inclined surface 4c shown in FIG. 10 is provided with a layer 4f made of a fluorine resin such as PTFE (polytetrafluoroethylene). The layer 4f made of fluororesin is formed with a thickness of several hundred μm, for example. The layer 4f made of fluororesin has oil repellency.

Regarding the exhaust-side inclined surface 4c shown in FIG. 10, similarly to the exhaust-side inclined surface 4c shown in FIG. A wettability changing portion 80 is provided in which the wettability with respect to oil is changed from above to below the exhaust-side inclined surface 4c so as to increase. A wettability changing portion 80 having a plurality of grooves 81 formed so that the lipophilicity increases from the top to the bottom of the inclined surface 4c is provided on the inner surface of the layer 4f made of fluororesin on the inclined surface 4c on the exhaust side. may

Each of the plurality of grooves 81 formed on the inner surface of the layer 4f made of fluororesin has a predetermined length L1 extending in the cylinder row direction of the exhaust-side inclined surface 4c over the entire vertical direction of the exhaust-side inclined surface 4c. The plurality of inclined surface side grooves 81 are formed so as to be separated from each other from the upper side to the lower side of the exhaust side inclined surface 4c. In addition, as shown in FIG. 2, the plurality of inclined surface side grooves 81 may be partially provided, for example, between boss portions provided on the bottom surface 4a.

Each of the plurality of inclined surface side groove portions 81 is formed in a U-shaped cross section having a predetermined width W11 and a predetermined depth D11. The width W11 of the plurality of inclined surface side grooves 81 is set to be the same, and the depth D11 of the plurality of inclined surface side grooves 81 is set so as to become shallower from the upper side to the lower side of the exhaust side inclined surface 4c. .

In this way, the plurality of inclined surface-side grooves 81 are formed such that the depth D11 becomes shallower from above the exhaust-side inclined surface 4c toward the lower side, thereby increasing the lipophilicity from above the exhaust-side inclined surface 4c. It is formed so that it becomes high toward the downward direction.

As a result, the wettability of the oil is changed so that the oleophilicity increases from the upper side to the lower side of the exhaust side inclined surface 4c, thereby moving the oil from the upper side to the lower side of the exhaust side inclined surface 4c. The oil can be guided to the bottom surface 4a below the side inclined surface 4c, and the residence time of the oil on the exhaust side inclined surface 4c can be reduced.

FIG. 11 is a cross-sectional view showing a modification of the bottom surface 4a shown in FIG. A bottom surface 4a shown in FIG. 11 is provided with a layer 4g made of a fluorine resin such as PTFE (polytetrafluoroethylene). The layer 4g made of fluororesin is formed with a thickness of several hundred μm, for example. The layer 4g made of fluororesin has oil repellency.

Similarly to the bottom surface 4a shown in FIG. 9, the bottom surface 4a shown in FIG. 11 also has a higher lipophilicity from both ends of the bottom surface 4a in the width direction orthogonal to the cylinder shaft 2a and the crankshaft 6a toward the vicinity of the central portion. A bottom surface wettability changing portion 90 is provided in which the wettability with respect to oil is changed toward the center portion in the width direction of the bottom surface 4a.

The bottom surface wettability changing portion 90 has an exhaust side changing portion 90a provided on the exhaust side with the cylinder shaft 2a interposed therebetween, and an intake side changing portion 90b provided on the intake side with the cylinder shaft 2a interposed therebetween. The exhaust-side changing portion 90a includes a plurality of exhaust-side grooves as a plurality of bottom-side concave portions formed in the bottom surface 4a such that the lipophilicity increases from the exhaust side of the bottom surface 4a toward the central portion (cylinder shaft 2a) of the bottom surface 4a. A portion 91a is provided. Each of the plurality of exhaust-side grooves 91a is formed to extend in the extending direction of the bottom surface 4a (cylinder row direction) over the entire exhaust side of the bottom surface 4a relative to the cylinder shaft 2a. They are formed separately from the exhaust side of the bottom surface 4a at the central portion. Note that the plurality of exhaust-side grooves 91a may be partially provided, for example, between bosses provided on the bottom surface 4a, as shown in FIG.

Each of the plurality of exhaust-side grooves 91a is formed in a U-shape having a predetermined width W21 and a predetermined depth D21. The widths W21 of the plurality of exhaust-side grooves 91a are set to be the same, and the depths D2 of the plurality of exhaust-side grooves 91a are set to decrease from the exhaust side toward the central portion of the bottom surface 4a.

In this way, the plurality of exhaust-side grooves 91a are formed so that the depth D21 becomes shallower from the exhaust side toward the center of the bottom surface 4a. It is formed so that it becomes high.

The intake-side changing portion 90b includes a plurality of intake-side grooves as a plurality of bottom-side concave portions formed on the bottom surface 4a such that the oleophilicity increases from the intake side of the bottom surface 4a toward the central portion (cylinder shaft 2a) of the bottom surface 4a. A portion 91b is provided. Each of the plurality of intake-side grooves 91b is formed to extend in the cylinder row direction of the bottom surface 4a over the entire intake side of the bottom surface 4a with respect to the cylinder shaft 2a. are spaced apart from each other in the center. Note that the plurality of intake-side grooves 91b may be partially provided, for example, between bosses provided on the bottom surface 4a, as shown in FIG.

Each of the plurality of intake-side grooves 91b is formed to have a U-shaped cross section having a predetermined width W31 and a predetermined depth D31. The width W31 of the plurality of intake-side grooves 91b is set to be the same, and the depth D31 of the plurality of intake-side grooves 91b is set to decrease from the intake side toward the central portion of the bottom surface 4a.

In this way, the plurality of intake-side grooves 91b are formed so that the depth D31 becomes shallower from the exhaust side toward the center of the bottom surface 4a. It is formed so that it becomes high.

In this embodiment, the exhaust-side changing portion 90a and the intake-side changing portion 90b are provided so as to be line-symmetrical with respect to the cylinder shaft 2a. The exhaust-side changing portion 90a is formed so that the exhaust-side groove portion 91a becomes shallower from the exhaust side toward the central portion of the bottom surface 4a. Since they are shallowly formed, the bottom surfaces of the plurality of exhaust-side grooves 91a and the plurality of intake-side grooves 91b are formed in an inverted V shape as a whole in a cross section orthogonal to the cylinder shaft 2a.

In the portion of the bottom surface 4a shown in FIG. 11 closer to the exhaust side than the cylinder shaft 2a, the plurality of exhaust-side groove portions 91a are formed such that the depth D4 is deeper from the exhaust side of the bottom surface 4a toward the central portion. , the lipophilicity is formed so as to increase from the exhaust side of the bottom surface 4a toward the central portion side.

In this way, by changing the wettability to the oil so that the lipophilicity increases from the exhaust side toward the central portion of the bottom surface 4a, warm oil dripping from the exhaust-side inclined surface 4c and the camshaft is removed. , can be moved from the exhaust side of the bottom surface 4a toward the central portion side to guide the oil to the vicinity of the center portion in the width direction of the bottom surface 4a located above the water jacket 14, and the width at which the temperature is the lowest at the bottom surface 4a It is possible to increase the residence time of the oil in the vicinity of the central portion of the direction.

In addition, by changing the wettability with oil so that the oleophilicity increases from the intake side toward the central portion of the bottom surface 4a, even on the intake side of the bottom surface 4a, the oil drips from the intake-side inclined surface 4b and the camshaft. The warmed oil can be moved from the intake side toward the central portion of the bottom surface 4a and guided to the vicinity of the central portion of the bottom surface 4a located above the water jacket 14, where the temperature is lowest at the bottom surface 4a. It is possible to increase the residence time of the oil in the vicinity of the central portion where

By providing the intake-side changing portion 90b in addition to the exhaust-side changing portion 90a, it is possible to suppress further movement of the oil, which has been moved toward the widthwise central portion of the bottom surface 4a by the exhaust-side changing portion 90a, toward the intake side. , it is easy to further increase the retention time of the oil in the vicinity of the central portion of the bottom surface 4a located above the water jacket 14 and cooled by the cooling water.

In the present embodiment, the plurality of inclined surface grooves 61 formed on the exhaust side inclined surface 4c have the same width W1 and a depth D1 that increases downward from above the exhaust side inclined surface 4c. However, the width W1 may be increased from the upper side to the lower side of the exhaust-side inclined surface 4c while the depth D1 is set constant.

In this embodiment, on the exhaust-side inclined surface 4c, the plurality of inclined-surface-side grooves 71 formed in the layer 4f made of fluororesin have the same width W2 and a depth D2 above the exhaust-side inclined surface 4c. However, the width W2 of the head-side return passage 42 may be increased from the upstream side toward the downstream side while the depth D2 is set constant.

In this embodiment, the plurality of grooves 61 and 81, the plurality of exhaust-side grooves 71a and 91a, and the plurality of intake-side grooves 71b and 91b are formed to have a U-shaped cross section. It is also possible to form other cross-sectional shapes such as. The plurality of grooves 61, 81, the plurality of exhaust side grooves 71a, 91a, and the plurality of intake side grooves 71b, 91b may be formed only in part of the cylinder head in the cylinder row direction.

In the present embodiment, the plurality of grooves 61 formed on the exhaust-side inclined surface 4c are formed so that the width W1 is set to be the same and the depth D1 increases from the top to the bottom of the exhaust-side inclined surface 4c. However, in addition to the change in the depth D1, the width W1 may be increased from the upper side to the lower side of the exhaust-side inclined surface 4c. As a result, the oleophilicity is further enhanced from the upper side to the lower side of the exhaust-side inclined surface 4c.

In this embodiment, on the exhaust-side inclined surface 4c, the plurality of inclined-surface-side grooves 81 formed in the layer 4f made of fluororesin have the same width W2 and a depth D2 above the exhaust-side inclined surface 4c. However, in addition to the change in the depth D2, the width W2 of the exhaust-side inclined surface 4c may be increased from the top to the bottom. As a result, the oleophilicity is further enhanced from the upper side to the lower side of the exhaust-side inclined surface 4c.

In the present embodiment, a plurality of slope-side recesses and a plurality of deck-side recesses (hereinafter also referred to as “plurality of recesses”) provided in the slope surface wettability changing portions 60 and 80 and the bottom surface wettability changing portions 70 and 90 are provided. is formed by a plurality of inclined surface side grooves 61, 81, a plurality of exhaust side grooves 71a, 91a, and a plurality of intake side grooves 71b, 91b (hereinafter also referred to as "a plurality of grooves"). The plurality of grooves are formed by arranging a plurality of dimple rows aligned in the cylinder row direction on the exhaust side inclined surface 4c and the bottom surface 4a in the width direction (direction orthogonal to the cylinder axis 2a and the crankshaft 6a). may be The row of dimples is, for example, circular in plan view, and is formed by arranging a plurality of dimples arranged side by side along the direction of the crankshaft 6a. There may be. A plurality of dimples forming a dimple row aligned in the direction of the crankshaft 6a are formed with the same diameter as depth and width. The dimple rows arranged in the vertical direction of the inclined surface 4c and in the width direction of the bottom surface 4a have the same diameter as the depth and width of the grooves 61, 71a, 71b, 81, 91a, and 91b. and the width direction of the bottom surface 4a.

In the present embodiment, the bottom surface wettability changing portions 70 and 90 include the exhaust side changing portions 70a and 90a and the intake side changing portions 70b and 90b, but may include only the exhaust side changing portions 70a and 90a.

In this embodiment, the inclined surface changing portions 60 and 80 and the bottom surface wettability changing portions 70 and 90 are provided. may

The present invention is not limited to the illustrated embodiments, and various improvements and design changes are possible without departing from the gist of the invention.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to provide an engine oil passage structure capable of suppressing an increase in temperature of oil, so that it may be preferably used in the engine manufacturing industrial field.

1 Engine 10 Engine body 3 Cylinder block 4 Cylinder head 4a Bottom surface 4c Inclined surface 11 Exhaust device 14 Head-side water jacket (cooling part)
20 Oil passage 30 Oil pan 31 Oil pump 70 Inclined surface wettability changing portion 71 Plural inclined surface side recesses 80 Bottom surface wettability changing portion 81a Plural bottom surface side recesses

Claims (12)

An oil passage structure for an engine in which oil stored in an oil pan arranged below a cylinder block of an engine body is transported by an oil pump, supplied to a lubricated part, and then returned to the oil pan for circulation,
A cylinder head concave portion provided in the cylinder head of the engine body and dripping oil after lubricating the lubricated portion,
The cylinder head recess has a bottom surface extending in a width direction perpendicular to the crankshaft of the engine body provided at a position including an upper portion of a cooling portion that cools the cylinder head, and an outer side from the width direction end of the bottom surface. and an inclined surface that slopes upward toward
The inclined surface has an inclined surface wettability changing portion that changes the wettability with respect to oil from the top to the bottom to promote the flow of oil,
The oil passage structure for an engine, wherein the bottom surface has a bottom surface wettability changing portion that changes the wettability with respect to oil toward the cooling portion to promote oil flow. 2. The inclined surface wettability changing portion according to claim 1, comprising a plurality of inclined surface side concave portions formed on the inclined surface such that lipophilicity increases from the side opposite to the bottom surface toward the bottom surface. Engine oil passage structure. 3. The bottom surface wettability changing portion includes a plurality of bottom surface side recesses formed on the bottom surface such that lipophilicity increases from the inclined surface side toward the cooling portion side. Oil passage structure of the described engine. The cylinder head is made of a metal material,
3. The engine oil passage structure according to claim 2, wherein the plurality of inclined surface side recesses are formed in the inclined surface so as to have a greater depth from the opposite bottom surface side toward the bottom surface side. The cylinder head is made of a metal material,
5. The oil passage structure for an engine according to claim 2, wherein said plurality of inclined surface side recesses are formed on said inclined surface so as to increase in width from said opposite bottom surface side toward said bottom surface side. The cylinder head is made of a metal material,
4. The engine oil passage structure according to claim 3, wherein the plurality of bottom-side recessed portions are formed in the bottom surface to have a greater depth toward the cooling portion side. The cylinder head is made of a metal material,
7. The oil passage structure for an engine according to claim 3, wherein said plurality of bottom-side recessed portions are formed on said bottom surface so as to have a large width toward said cooling portion side. A layer made of a fluororesin material is provided in the cylinder head concave portion,
3. The engine oil passage structure according to claim 2, wherein the plurality of inclined surface side recesses are formed in the inclined surface so that the depth thereof becomes shallower from the opposite bottom surface side toward the bottom surface side. A layer made of a fluororesin material is provided in the cylinder head concave portion,
9. The engine oil passage structure according to claim 2 or 8, wherein said plurality of inclined surface side recesses are formed on said inclined surface so as to increase in width from said opposite bottom surface side toward said bottom surface side. A layer made of a fluororesin material is provided in the cylinder head concave portion,
4. The engine oil passage structure according to claim 3, wherein the plurality of bottom-side concave portions are formed in the bottom surface so that the depth thereof is shallow toward the cooling portion side. A layer made of a fluororesin material is provided in the cylinder head concave portion,
11. The engine oil passage structure according to claim 3 or 10, wherein the plurality of bottom-side concave portions are formed on the bottom surface to have a large width toward the cooling portion. The cylinder head is provided with a water jacket for flowing cooling water from a water pump,
The oil passage structure for an engine according to any one of claims 1 to 11, wherein the cooling portion is configured by the water jacket.

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