JP6394555B2 - Engine oil passage structure - Google Patents

Description

  The present invention relates to an oil passage structure for an engine that uses engine oil to lubricate and cool the engine.

  Patent Document 1 discloses an oil passage core structure for forming a head-side cooling oil passage in a cylinder head in which a spark plug, an intake port and an exhaust port are formed. The oil passage core communicates between the oil inflow passage and the oil outflow passage by flowing around the first boss forming the oil inflow passage, the second boss forming the oil outflow passage, the spark plug and the exhaust port. A cooling passage portion that forms a cooling passage. The engine oil flows in the head side cooling oil passage formed by the oil passage core configured as described above, whereby the cylinder head is cooled.

JP2013-72354A

  However, in the head side cooling oil passage formed in the cylinder head by the oil passage core described above, the cooling passage provided between the oil inflow passage and the oil outflow passage is branched around the spark plug and the exhaust port. Is formed.

  For this reason, the flow rate of the engine oil flowing through the cooling passage is lower than the flow rate of the engine oil flowing through the oil inflow passage and the oil outflow passage, and as a result, the cooling efficiency of the cylinder head is lowered. In this case, if it changes to the specification which raises the flow velocity of engine oil, an engine will be overcooled at the time of engine cold start, and the warming-up performance of an engine will fall.

  An object of the present invention is to provide an oil passage structure for an engine that can improve both the warm-up performance and the cooling efficiency of the engine in consideration of the above-described circumstances.

In the engine oil passage structure according to the present invention, an oil passage for flowing engine oil is provided in each of the crankcase, the cylinder, and the cylinder head, and the oil passage of the cylinder head is provided by an exhaust port provided in the cylinder head. An engine oil passage structure configured to recirculate and cool the engine oil to the periphery and guide the oil to an oil passage of the cylinder, wherein at least one oil passage of the cylinder head and the cylinder includes a passage wall surface thereof. A protrusion projecting in a direction perpendicular to the direction of the flow path of the oil passage, and a part of the oil passage of the cylinder head is provided on the top surface of the cylinder head and opens upward. And a lid member that covers the open portion from above, and the lid member includes the open portion. Convexes corresponding to the shape of the road is formed to project, by the convex portion is engaged with the channel of the open portion, wherein a portion of the oil passage of the cylinder head is configured Is.

  According to the present invention, the oil passage of at least one of the cylinder head and the cylinder is provided with a protrusion protruding on the passage wall surface in a direction perpendicular to the direction of the flow path of the oil passage. For this reason, when the temperature of the engine oil is low and its viscosity is high, the flow rate of the engine oil is lowered by the protrusions, resulting in a decrease in engine cooling performance and an increase in warm-up speed, improving engine warm-up performance. Can be made. Further, when the temperature of the engine oil is high and its viscosity is low, the flow rate of the engine oil is increased, and the heat exchange efficiency is increased due to the presence of the protrusion, so that the cooling efficiency of the engine can be improved.

1 is a left side view showing a motorcycle equipped with an engine to which an embodiment of an oil passage structure of an engine according to the present invention is applied. The front view which shows the engine of FIG. 1 with an oil cooler. The right view which shows the engine of FIG.1 and FIG.2. 4 is a system diagram showing an oil passage structure of the engine in FIGS. The top view which shows the cylinder of FIG.2 and FIG.3. FIG. 4 is a perspective view showing an oil passage forming core and the like provided in the cylinder head of FIGS. 2 and 3. The VII perspective view of FIG. VIII arrow directional view of FIG. The top view which shows the cylinder head of FIG.2 and FIG.3. The enlarged plan view which expands and shows the open part of FIG. FIG. 10 is a plan view showing a cylinder head in a state in which a lid member is attached to the open part of FIG. 9. The bottom view which shows the cover member of FIG. FIG. 13 is a perspective view showing the lid member of FIGS. 11 and 12 as viewed from the bottom side. Sectional drawing which follows the XIV-XIV line | wire of FIG. The enlarged plan view which expands and shows the XV part of FIG. Sectional drawing which follows the XVI-XVI line | wire of FIG.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a left side view showing a motorcycle equipped with an engine to which an embodiment of an oil passage structure of an engine according to the present invention is applied. FIG. 2 is a front view showing the engine of FIG. 1 together with an oil cooler. FIG. 3 is a right side view showing the engine of FIGS. 1 and 2. In the present embodiment, front / rear, left / right, and upper / lower expressions are based on the driver when riding the vehicle.

  A motorcycle 10 shown in FIG. 1 has a vehicle body frame 11 having a head pipe 12 at a front end portion. The vehicle body frame 11 is a so-called cradle frame, and includes the head pipe 12, the main tube 13, the down tube 14, and a pair of left and right seat rails 15.

  A steering mechanism 16 is pivotally supported on the head pipe 12 positioned above the front portion of the vehicle body frame 11. A front fork 17 and a handle bar 18 that rotatably support a front wheel 19 and incorporate a suspension mechanism are attached to the steering mechanism 16. Using the handle bar 18, the front wheel 19 is steered left and right. A front fender 20 is fixed to the front fork 17 so as to cover the upper part of the front wheel 19.

  The main tube 13 extends from the upper rear surface of the head pipe 12 obliquely downward in the vehicle, is curved and extends downward in the vehicle, and a lower end portion is coupled to a pivot bracket (not shown). Further, the down tube 14 extends from the lower rear surface of the head pipe 12 to the lower side of the vehicle, curves and extends toward the rear of the vehicle, and the rear end portion is coupled to the pivot bracket. The pivot bracket is provided with a pivot shaft support (not shown), and the swing arm 23 is pivotally supported on the pivot shaft support so as to be swingable in the vehicle vertical direction. A rear wheel 24 is rotatably supported at the rear end of the swing arm 23.

  A pair of left and right seat rails 15 are coupled to the main tube 13 and extend rearward of the vehicle. The pair of left and right seat rails 15 are connected by a plurality of frame bridges (not shown) sequentially arranged in the vehicle longitudinal direction. Further, these seat rails 15 are supported by the pivot bracket via a pair of left and right seat pillars 25.

  A fuel tank 26 is supported by the main tube 13 at a position behind the head pipe 12. A seat 27 is supported by the seat rail 15 adjacent to the rear of the fuel tank 26. Further, a rear fender 28 that covers the upper portion of the rear wheel 24 is supported by the seat rail 15 in a suspended manner. Further, a rear cushion unit 29 is loaded between the seat rail 15 and the seat pillar 25 and the swing arm 23, and an impact load from the rear wheel 24 is buffered.

  An engine 30 is mounted between the main tube 13 and the down tube 14. The engine 30 is a four-cycle single cylinder engine, for example, and is positioned below the fuel tank 26. The engine 30 drives the rear wheel 24 via a drive chain 31 wound around the rear wheel 24. A carburetor (or throttle body) (not shown) constituting an engine intake system, an air cleaner, and the like are sequentially connected to a rear portion of a cylinder head 43 (described later) constituting the engine 30. Further, an exhaust pipe (not shown) and an exhaust muffler that are engine exhaust systems are sequentially connected to the front portion of the cylinder head 43.

  The steering mechanism 16 or the front fork 17 is provided with a front cover 32 that covers the upper front of the vehicle, and a headlight 33 and the like are disposed on the front cover 32. In addition, a pair of left and right side covers 34 are attached to the main tube 13 and the seat rail 15 so as to cover the regions below the rear portion of the fuel tank 26 and below the front portion of the seat 27 behind the engine 30. Further, a rear cover 35 is attached to the seat rail 15 so as to cover a region below the rear portion of the seat 27 above the rear wheel 24.

  As shown in FIGS. 2 and 3, the engine 30 is a four-cycle single-cylinder engine as described above, and includes a crankcase 41, a cylinder 42 coupled to an upper front portion of the crankcase 41, and the cylinder 42. And a head cover 44 for closing the top of the cylinder head 43.

  The crankcase 41 is configured by connecting a left half 41A and a right half 41B at a coupling surface 41C, and a magnet cover 45 is provided on the left half 41 and a clutch cover 46 is provided on the right half 41B. A crankshaft 47 is rotatably supported in the crankcase of the crankcase 41. A transmission chamber 50 is formed in the crankcase 41 adjacent to the crank chamber. A transmission (T / M) 51 including a counter shaft 39 and a drive shaft 40 (both shown in FIG. 4) is accommodated in the mission chamber 50. An oil pan 49 for storing engine oil is provided at the lower part of the crankcase 41.

  The cylinder 42 is coupled to the crankcase 41 in a slightly forward inclined posture. A cylindrical cylinder bore 52 is formed in the cylinder 42. A piston 53 connected to the crankshaft 47 via a connecting rod (not shown) is disposed in the cylinder bore 52 so as to be reciprocally movable. Further, as shown in FIG. 5, a cam chain chamber 54 is formed in the cylinder 42 adjacent to the cylinder bore 52.

  The cylinder head 43 shown in FIGS. 2 and 3 is coupled to the top of the cylinder 42 and closes the cylinder bore 52 to form a combustion chamber 55 with the piston 53. As the air-fuel mixture burns in the combustion chamber 55, the piston 53 reciprocates. Further, the cylinder head 43 is provided with a pair of intake ports 56 for supplying air-fuel mixture into the combustion chamber 55 on the back wall side, and exhaust for exhausting combustion gas generated in the combustion chamber 55 on the front wall side. A port 57 is provided.

  3 and 9, the cylinder head 43 has a valve operating mechanism for driving a pair of intake valves 58 for opening and closing the intake ports 56 and a single exhaust valve 59 for opening and closing the exhaust ports 57. 60 is accommodated between the head cover 44 and the head cover 44. The camshaft 61 of the valve mechanism 60 is driven between the crankshaft 47 and a cam chain (not shown). This cam chain is disposed in the cam chain chamber 54 (FIG. 5) of the cylinder 42 and the cam chain chamber 62 (FIG. 9) of the cylinder head 43.

  Further, bolt holes 63 are formed at four locations around the cylinder bore 52 and the combustion chamber 55 in the cylinder 42 and the cylinder head 43, respectively, as shown in FIGS. By inserting stud bolts 64 into these bolt holes 63, the cylinder 42 and the cylinder head 43 are coupled to the crankcase 41.

  Incidentally, as shown in FIG. 3, the engine 30 configured as described above has an oil passage structure 65. The oil passage structure 65 includes a crankcase-side oil passage 66, a cylinder-side oil passage 67, and a cylinder head side. An oil passage 68 is provided.

  The crankcase-side oil passage 66 is an oil passage provided in the crankcase 61 and supplies engine oil to the lubrication portions in the crankcase 41 and the cylinder 42 for lubrication. The cylinder-side oil passage 67 is an oil passage provided in the cylinder 62 and cools the periphery of the combustion chamber 55 with engine oil. Further, the cylinder head side oil passage 68 is an oil passage provided in the cylinder head 63 and lubricates the valve mechanism 60 with engine oil and cools the periphery of the exhaust port 57.

  As shown in FIGS. 2 to 4, the first oil passage portion 71, the oil pump 69, the second oil passage portion 72, the oil filter 70, and the third oil passage portion 73 are sequentially connected to the crankcase side oil passage 66. In addition, a fourth oil passage 74 is connected to the oil filter 70.

  The first oil passage portion 71 is connected to the oil pan 49 directly or via an oil strainer (not shown). The oil pump 69 is a mechanical oil pump that is driven by an auxiliary machine drive gear (not shown) that is integrally rotated with the crankshaft 47. Accordingly, the output of the oil pump 69 depends on the rotation speed of the crankshaft 47 (that is, the rotation speed of the engine 30), and a larger amount of engine oil is discharged as the rotation speed of the crankshaft 47 becomes higher.

  When the oil pump 69 is operated, the engine oil in the oil pan 49 is discharged from the oil pump 69 through the first oil passage portion 71 directly or after the foreign matter is removed by the oil strainer. Then, the oil flows into the oil filter 70 and foreign matters in the engine oil are removed.

  The engine oil from which foreign matter has been removed by the oil filter 70 passes through the third oil passage portion 73, and is a piston that slides in the lubricating portions of the engine 30, that is, the crankshaft 47 in the crank chamber and the cylinder bore 52 of the cylinder 42. 53, supplied to the transmission 51 in the transmission chamber 50, etc., and lubricates the crankshaft 47, the piston 53, and the transmission 51 (including the counter gear 39 and the drive gear 40). Further, the fourth oil passage portion 74 is connected to the fifth oil passage portion 75 of the cylinder side oil passage 67.

  As shown in FIGS. 2 and 3, the cylinder side oil passage 67 includes a fifth oil passage portion 75 and a sixth oil passage portion 76 that communicate with each other, and an inflow side oil hose 83 and an oil cooler in the fifth oil passage portion 75. 84 and the 8th oil passage part 78 connected via the outflow side oil hose 85, and the 10th oil passage part 80 and the 11th oil passage part 81 which are connected mutually. The cylinder head side oil passage 68 includes a seventh oil passage portion 77 communicating with the sixth oil passage portion 76 of the cylinder side oil passage 67, an eighth oil passage portion 78 and a tenth oil passage of the cylinder side oil passage 67. And a ninth oil passage portion 79 communicating with the portion 80.

  As shown in FIGS. 2 and 3, the fifth oil passage portion 75 of the cylinder side oil passage 67 is formed to extend linearly in the horizontal direction below the front wall of the cylinder 42. Part of the engine oil that has flowed into the fifth oil passage portion 75 reaches the seventh oil passage portion 77 of the cylinder head side oil passage 68 via the sixth oil passage portion 76, and this seventh oil passage portion. The valve operating mechanism 60 (in particular, the camshaft 61) is guided from 77 to lubricate the valve operating mechanism 60.

  Here, as shown in FIGS. 2 and 5, the sixth oil passage portion 76 intersects the fifth oil passage portion 75 of the cylinder side oil passage 67 at right angles, and extends upward to be formed in the cylinder 42. Is done. The seventh oil passage portion 77 communicates with the sixth oil passage portion 76 of the cylinder-side oil passage 67 and is formed to extend in the substantially vertical direction to the cylinder head 43, so that the camshaft 61 of the valve mechanism 60. To the neighborhood.

  As shown in FIG. 2, the remaining engine oil that has flowed into the fifth oil passage portion 75 of the cylinder-side oil passage 67 flows into the oil cooler 84 via the inflow side oil hose 83 and is cooled. As shown in FIGS. 1 and 2, the oil cooler 84 is disposed obliquely forward and upward of the engine 30 in the down tube 14 of the vehicle body frame 11. In particular, the oil cooler 84 is preferably arranged so as to avoid being exposed to the front wheels 19 and the front fender 20 so as to be easily exposed to the traveling wind of the motorcycle 10. A cooling fan 86 that generates cooling air is disposed on the back surface of the oil cooler 84. Accordingly, the oil cooler 84 cools the inflowing engine oil by exchanging heat with the cooling air from the cooling fan 86 and the traveling air of the motorcycle 10.

  The engine oil cooled by the oil cooler 84 flows into the eighth oil passage portion 78 of the cylinder side oil passage 67 through the outflow side oil hose 85, as shown in FIGS. The oil passage 78 flows into the ninth oil passage 79 of the cylinder head side oil passage 68.

  As shown in FIGS. 5 and 6, the eighth oil passage portion 78 is formed at a corner of the front wall of the cylinder 42 with the left side wall. As will be described in detail later, the ninth oil passage portion 79 is formed around the exhaust port 57 in the cylinder head 43, and allows engine oil from the eighth oil passage portion 78 of the cylinder side oil passage 67 to pass through the cylinder head 43. The periphery of the exhaust port 57 is cooled by flowing (refluxing) around the exhaust port 57.

  The engine oil that has flowed in the ninth oil passage portion 79 then flows into the tenth oil passage portion 80 of the cylinder-side oil passage 67 as shown in FIGS. 4 and 5. As will be described in detail later, the tenth oil passage portion 80 is formed around the cylinder bore 52 at the joint surface of the cylinder 42 with the cylinder head 43, and allows the engine oil from the ninth oil passage portion 79 to flow in an annular shape. Then, the periphery of the combustion chamber 55 is cooled. The engine oil cooled around the combustion chamber 55 is returned to the oil pan 49 in the crankcase 41 through the eleventh oil passage portion 81 of the cylinder-side oil passage 67 as shown in FIGS. It is. The eleventh oil passage portion 81 is formed in a vertical direction at a corner portion of the front wall of the cylinder 42 with the left front wall.

  As shown in FIGS. 6 to 8, the ninth oil passage portion 79 that cools the periphery of the exhaust port 57 in the cylinder head 43 by recirculating the engine oil is a lower side formed by a lower core 90. It has a flow path portion 87, an upper flow path portion 88 formed by the upper core 91, and a discharge flow path portion 89 formed by cutting such as drilling. However, as shown in FIGS. 9, 11, and 14, the upper flow path portion 88 is actually provided with an open portion 92 provided on the top surface of the cylinder head 43 and opened upward by the upper core 91. The upper flow path portion 88 is formed using a lid member 93 that is formed and covers the open portion 92 from above.

  As shown in FIGS. 6 to 8, the lower flow path portion 87 is formed in a substantially semicircular arc shape below the exhaust port 57 in the cylinder head 43 and extends to the right side of the exhaust port 57. It is formed. The upstream end of the lower flow path portion 87 communicates with the eighth oil flow path portion 78 of the cylinder side oil passage 67. The lower core 92 that forms the lower flow path portion 87 has a recess 94 formed on the surface facing the exhaust port 57. A direction perpendicular to the direction of the flow path (that is, the flow direction of the engine oil flowing in the lower flow path portion 87) on the flow path wall surface facing the exhaust port 57 of the lower flow path portion 87 by the recess 94. And the protrusion 95 which protrudes inside the lower side flow path part 87 is formed.

  As shown in FIGS. 6 and 9, the open portion 92 of the upper flow path portion 88 is a region above the exhaust port 57 and below the valve mechanism 60, and one intake valve 58 and one pair arranged. Formed between the exhaust valve 59 and the exhaust valve 59. The open portion 92 has an upstream end communicating with the lower flow path portion 87 and a downstream end communicating with the discharge flow path portion 89. In addition, the opening 92 is formed in a meandering manner, and the flow path length is longer than that in a straight line, and the heat exchange efficiency of the engine oil flowing inside is increased.

  Furthermore, as shown in FIGS. 6 to 8, a recess 96 is formed on the outer surface of the upper core 91 that forms the opening 92. As shown in FIG. 10, the recess 96 causes the flow passage wall surface of the opening portion 92 to be perpendicular to the direction of the flow passage (that is, the flow direction of engine oil flowing in the opening portion 92) and A protrusion 97 protruding inward is formed.

  As shown in FIGS. 11 to 14, the cover member 93 of the upper flow path portion 88 covers the open portion 92 from above as described above, and a convex portion 98 corresponding to the shape of the flow path of the open portion 92 is provided. Protrusively formed. The convex portion 98 of the lid member 93 is inserted into and engaged with the flow path of the open portion 92, so that the gap between the convex portion 98 and the open portion 92 is configured as the upper flow path portion 88 of the ninth oil passage portion 79. Is done. Instead of the protrusions 97 (FIG. 10) formed on the flow path wall surface of the open portion 92, as shown in FIG. 13, the upper flow is applied to all or a part of the side surface of the convex portion 98 of the lid member 93. You may form the protrusion 99 which protrudes in the direction perpendicular | vertical with respect to the direction of the flow path of the path part 88. FIG.

  Further, as shown in FIGS. 9, 13, and 14, the lid member 93 uses a mounting bolt 100 to connect the cylinder head in a state where the joining surface 93 </ b> A of the lid member 93 and the joining surface 92 </ b> A of the opening 92 are joined. 43. At this time, one of the joining surface 93A of the lid member 93 and the joining surface 93A of the opening 92 (for example, the joining surface 93A of the lid member 93) is a non-processed surface that is not flattened, that is, a casting surface. Is formed. Thereby, gas, such as air bubbles, is configured to be able to pass through the gap between the joint surface 93A of the lid member 93 and the joint surface 92A of the opening 92. In addition, the code | symbol 101 in FIG. 11 shows the position of the cam housing which accommodates the valve operating mechanism 60. FIG.

  As shown in FIGS. 6 and 7, the discharge flow path portion 89 of the ninth oil passage portion 79 communicates with the upper flow path portion 88 and is processed to be inclined downward to the left side of the exhaust port 57. The downstream end of the discharge passage portion 89 communicates with the tenth oil passage portion 80 of the cylinder side oil passage 67. As described above, the engine oil flows in the ninth oil passage portion 79 constituted by the lower flow passage portion 87, the upper flow passage portion 88, and the discharge flow passage portion 89, so that the exhaust port 57 of the cylinder head 43 The surroundings are cooled.

  As shown in FIGS. 5, 15, and 16, the tenth oil passage portion 80 is formed in an annular shape around the cylinder bore 52 (combustion chamber 55) on the joint surface of the cylinder 42 with the cylinder head 43. The groove 102 and the gasket 103 (FIG. 3) sandwiched between the cylinder 42 and the cylinder head 43 are defined. The annular groove 102 is an inlet portion 102A corresponding to the lower region of the exhaust port 57 of the cylinder head 43, and communicates with the discharge passage portion 89 of the ninth oil passage portion 79 of the cylinder head 43, and the cylinder bore 52 (combustion chamber 55). , And the outlet portion 102 </ b> B communicates with the eleventh oil passage portion 81 of the cylinder side oil passage 67.

  The annular groove 102 is also formed by a ring-shaped core (not shown). The ring-shaped core has a plurality of recesses on the inner peripheral surface and the outer peripheral surface, and the annular groove 102 corresponds to the recess. A plurality of protrusions 104 shown in FIGS. 15 and 16 are formed. The protrusions 104 are formed on both inner wall surfaces facing the annular groove 102 in a direction perpendicular to the flow direction of the annular groove 102 (that is, the flow direction of engine oil flowing in the annular groove 102) and inside the annular groove 102. Project to The engine oil flows in the tenth oil passage portion 80 (particularly the annular groove 102) configured as described above, whereby the periphery of the combustion chamber 55 in the cylinder 42 and the cylinder head 43 is cooled.

With the configuration as described above, according to the present embodiment, the following effects (1) to (6) are obtained.
(1) At least one of the wall surfaces of the ninth oil passage portion 79 of the cylinder head side oil passage 68 and the tenth oil passage portion 80 of the cylinder side oil passage 67 shown in FIG. 4, in the present embodiment, FIG. The flow passage wall surface in the open portion 92 of the upper flow passage portion 88 of the ninth oil passage portion 79 shown in FIG. 10 and the flow passage wall surface in the annular groove 102 of the tenth oil passage portion 80 shown in FIG. 5 and FIG. Protrusions 97 and 104 projecting inward of the flow path and in the direction perpendicular to the flow path direction of the open portion 92 and the annular groove 102 are provided.

  For this reason, when the temperature of the engine oil is low and the viscosity thereof is high, the flow rate of the engine oil is lowered by the protrusions 97 and 104. As a result, the cooling performance of the engine 30 is lowered and the warming speed is increased. Can improve the warming performance. Further, when the temperature of the engine oil is high and its viscosity is low, the flow rate of the engine oil is increased, and the heat exchange efficiency is increased due to the presence of the protrusions 97 and 104, so that the cooling efficiency of the engine 30 can be improved. .

(2) The protrusion 97 in the open portion 92 of the upper flow path portion 88 of the ninth oil passage portion 79 shown in FIGS. 6, 9 and 10, and the annular groove of the tenth oil passage portion 80 shown in FIGS. Due to the presence of the projections 104 in 102, peeling vortices are generated at the tips of the projections 97, 104 in the engine oil flowing in the opening 92 and the annular groove 102. A turbulent boundary layer is formed by the generation of the separation vortex, and the engine oil increases in flow along the wall surface of the open portion 92 and the annular groove 102 and heat exchange becomes active. As a result, the efficiency of heat transfer between the open portion 92 and the wall surface of the annular groove 102 and the engine oil increases, so that the cooling efficiency of the engine 30 can be further improved.

  Here, the turbulent boundary layer is a boundary layer compared with the laminar boundary layer. In other words, the laminar boundary layer is a boundary layer composed of laminar flows, and the momentum exchange between fluids is performed only by molecular motion (collision of fluid molecules). Absent. For this reason, the laminar boundary layer exhibits a velocity distribution that gradually decreases toward the wall surface in the vicinity of the wall surface, in addition to separation before the turbulent boundary layer. Therefore, in the laminar boundary layer, the speed difference with the wall surface is small, and the frictional drag acting on the wall surface is small. This laminar boundary layer transitions to a turbulent boundary layer when the Reynolds number increases.

  On the other hand, the turbulent boundary layer is a boundary layer composed of turbulent flow and is thinner than the laminar boundary layer. In this turbulent boundary layer, the fluid having a large velocity and the fluid having a smaller momentum near the wall surface are mixed by the vortex motion of the fluid, and the momentum exchange is actively performed. For this reason, the momentum continues to be supplied to the fluid in the vicinity of the wall surface, and thus the turbulent boundary layer is less likely to be separated than the laminar boundary layer. An aircraft wing that focuses on this property and dislikes stalling is often provided with a vortex generator that is a projection for intentionally creating turbulence. In addition, the turbulent boundary layer has a velocity distribution that rapidly decreases in the vicinity of the wall surface because of the speed averaging, and therefore the frictional drag increases.

  (3) As shown in FIGS. 9, 11, and 14, the upper flow path portion 88 of the ninth oil passage portion 79 of the cylinder head side oil passage 68 has an open portion 92 that opens upward, and the lid member 93 is upward. It is comprised by covering from. For this reason, the flow path shape, flow path area, and the like of the upper flow path portion 88 can be easily designed, so that the degree of freedom in designing the flow path shape and the like of the upper flow path portion 88 can be improved.

  (4) Since the upper flow path portion 88 of the ninth oil passage portion 79 is formed by inserting and engaging the convex portion 98 of the lid member 93 in the open portion 92, the flow passage area is reduced to the core. It can be set small without being restricted by the wall thickness and drill diameter. For this reason, since the flow velocity of the engine oil flowing in the upper flow path portion 88 increases, the cooling efficiency of the engine 30 can be further improved.

  (5) As shown in FIGS. 10, 11 and 13, one of the joining surface 92A of the opening 92 and the joining surface 93A of the lid member 93 (for example, the joining surface 93A of the lid member 93) is a non-machined surface. It is formed with the casting surface which is. For this reason, when the joining surface 93A of the lid member 93 is joined to the joining surface 92A of the open portion 92 and the lid member 93 is coupled to the cylinder head 43 by the mounting bolt 100, gas flows through the gap between the joint surfaces 92A and 93A. Configured to be possible. For this reason, although the airtightness between the open portion 92 and the lid member 93 is lowered, air bubbles remaining in the upper flow path portion 88 constituted by the open portion 92 and the lid member 93 are allowed to pass through the gap between the joint surfaces 92A and 93A. Can be discharged. As a result, it is possible to prevent the upper flow path portion 88 from locally becoming high temperature.

  (6) As shown in FIGS. 6 and 10, the open portion 92 in the upper flow path portion 88 of the ninth oil passage portion 79 is formed to meander. Therefore, since the flow path length of the open part 92 can be set longer than when formed linearly, both the warming-up performance and the cooling efficiency of the engine 30 can be improved.

  As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention.

  For example, as shown in FIGS. 5 and 6, the lower flow passage portion 87 of the ninth oil passage portion 79 is provided by the lower core 90, and the open portion 92 of the upper flow passage portion 88 is provided by the upper core 91. 10 The annular groove 102 of the oil passage portion 80 has been described as being formed by ring-shaped cores. However, the lower channel portion 87, the open portion 92, and the annular groove 102 (particularly the annular groove 102) The core may be eliminated and formed by machining.

  Moreover, in order to increase a heat exchange area, you may form a fine protrusion part and a hollow part in the surface of the convex part 98 (FIG. 13) of the cover member 93 which comprises the upper flow path part 88. FIG. Further, the oil cooler 85 shown in FIGS. 1 and 2 may be abolished when the engine 30 is small and the cooling performance of the engine 30 is ensured even if the oil cooler 85 is abolished.

30 Engine 41 Crankcase 42 Cylinder 43 Cylinder head 49 Oil pan 55 Combustion chamber 57 Exhaust port 58 Intake valve 59 Exhaust valve 60 Valve mechanism 65 Oil passage structure 66 Crankcase side oil passage 67 Cylinder side oil passage 68 Cylinder head side oil passage 79 9th oil passage part 80 10th oil passage part 87 Lower flow path part 88 Upper flow path part 90 Lower core 91 Upper core 92 Opening part 93 Cover member 92A, 93A Joining surface 95 Lower flow path part Protrusion 97 Open portion protrusion 98 Convex portion 102 Annular groove 104 Annular groove protrusion

Claims (6)

Oil passages for flowing engine oil are provided in each of the crankcase, cylinder and cylinder head,
The oil passage of the cylinder head is an oil passage structure of an engine configured to recirculate and cool the engine oil around an exhaust port provided in the cylinder head and guide the oil to the oil passage of the cylinder,
The oil passage of at least one of the cylinder head and the cylinder is provided with a protrusion protruding on the passage wall surface in a direction perpendicular to the flow path direction of the oil passage ,
A part of the oil passage of the cylinder head is configured using an opening portion provided on the top surface of the cylinder head and opening upward, and a lid member that covers the opening portion from above.
A convex portion corresponding to the shape of the flow path of the open portion protrudes from the lid member, and the convex portion engages with the flow path of the open portion, so that the oil passage of the cylinder head is An oil passage structure for an engine characterized in that a part thereof is constructed . Oil passages for flowing engine oil are provided in each of the crankcase, cylinder and cylinder head,
  The oil passage of the cylinder head is an oil passage structure of an engine configured to recirculate and cool the engine oil around an exhaust port provided in the cylinder head and guide the oil to the oil passage of the cylinder,
  The oil passage of at least one of the cylinder head and the cylinder is provided with a protrusion protruding on the passage wall surface in a direction perpendicular to the flow path direction of the oil passage,
A part of the oil passage of the cylinder head is configured using an opening portion provided on the top surface of the cylinder head and opening upward, and a lid member that covers the opening portion from above.
The engine oil passage structure according to any one of claims 1 to 4, wherein a joint surface of one of the opening portion and the lid member is a cast surface as a non-processed surface. The oil passage structure for an engine according to claim 1 or 2 , wherein the oil passage provided with the protrusion is formed by a core during casting. 2. The oil passage structure for an engine according to claim 1 , wherein the protrusion of the oil passage of the cylinder head is provided on the flow path of the open portion or the convex portion of the lid member. The engine oil passage structure according to any one of claims 1 to 4 , wherein the oil passage of the cylinder head is provided between an intake valve and an exhaust valve installed in the cylinder head. . The engine oil passage structure according to any one of claims 1 to 5 , wherein the oil passage of the cylinder head is provided in a meandering manner.

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