JP5175768B2 - Cylinder head cooling oil passage for multi-cylinder engines - Google Patents

Description

  The present invention relates to an oil passage for cooling a cylinder head of an air-cooled multi-cylinder engine, and more particularly to a bypass oil passage provided in the oil passage.

  In the prior art, an engine that cools a cylinder head by providing a supply oil passage for guiding oil to a spark plug oil jacket of the cylinder head and a discharge oil passage for discharging the oil from the oil plug is disclosed (see, for example, Patent Document 1). .) In this technology, all the oil for cooling is sent to the oil jacket, so the cooling performance is high, but there is a considerable temperature difference between the oil before passing through the oil jacket and after passing through the oil jacket. In the cylinder block in which the discharge passage is arranged, a temperature difference occurs between the supply side and the discharge side, and there is a possibility that uneven cooling occurs in the cylinder block. For this reason, it is desired to reduce the temperature difference between the supply side and the discharge side of the cylinder block while maintaining the cooling performance of the oil jacket.

Japanese Patent Laying-Open No. 2006-97611 (FIGS. 5 and 6).

  The oil temperature difference between the supply side and the discharge side in the cylinder block is decreased to reduce cooling unevenness in the cylinder block.

The present invention solves the above problems, and the invention according to claim 1
In a cylinder head cooling oil passage in a multi-cylinder engine in which a supply oil passage and a discharge oil passage connected from a cylinder block to a spark plug oil jacket of a cylinder head are formed,
The present invention relates to a cylinder head cooling oil passage for a multi-cylinder engine, wherein a bypass oil passage that does not pass through the spark plug oil jacket is provided in a cylinder block.

A second aspect of the present invention is the cylinder head cooling oil passage of the multi-cylinder engine according to the first aspect,
The bypass oil passage is constituted by a groove formed on the upper surface of the cylinder block and a lower surface of the cylinder head closing the upper portion thereof.

According to a third aspect of the present invention, in the oil passage for cooling the cylinder head of the multi-cylinder engine according to the first or second aspect,
The multi-cylinder engine is an air-cooled engine in which air-cooled fins are provided in a cylinder block, and when the multi-cylinder engine is mounted on a vehicle, the supply oil path is on the front side of the cylinder with respect to the vehicle traveling direction. provided so as to be positioned, the oil discharge passage is characterized in that provided so as to be positioned on the rear side of the cylinder.

According to a fourth aspect of the present invention, in the cylinder head cooling oil passage of the multi-cylinder engine according to any one of the first to third aspects,
A parallel multi-cylinder engine having cylinders on both sides of a drive member storage chamber for storing a valve drive member, wherein a bypass oil passage is between the drive member storage chamber and a cylinder adjacent thereto. It is arranged in a block.

According to a fifth aspect of the present invention, in the cylinder head cooling oil passage of the multi-cylinder engine according to the fourth aspect,
The bypass oil passage is disposed only in one cylinder across the drive member accommodation chamber, and in the other cylinder across the drive member accommodation chamber, a supply oil passage connected to a groove formed on the upper surface of the cylinder block And the cross-sectional area of the drain oil passage is smaller than the cross-sectional areas of the supply oil passage and the drain oil passage on the one side.

According to a sixth aspect of the present invention, in the oil passage for cooling the cylinder head of the multi-cylinder engine according to the fourth or fifth aspect,
The bypass oil passage is formed by forming a groove on the upper surface of the cylinder block, and further, a branch for branching lubricating oil for lubricating the valve system to the upper surface of the cylinder block opposite to the bypass oil passage with the drive member housing chamber interposed therebetween. The oil passage is formed in the form of a groove.

In the invention of claim 1,
A bypass oil passage that does not pass through the oil jacket is provided in the cylinder block, and a part of the introduced oil does not pass through the oil jacket, but is directly guided from the supply oil passage to the discharge oil passage. The oil in the oil passage merges with the oil that is not heated by the oil jacket, thereby lowering the oil temperature in the discharge oil passage that passes through the cylinder block, reducing the temperature difference due to oil in the cylinder block, and causing uneven cooling in the cylinder block. I can hold it down.

In the invention of claim 2,
Compared with the case where the bypass oil passage is formed in the cylinder block by penetration processing, the configuration of the bypass oil passage can be simplified, the processing can be simplified, and the processing cost can be reduced.

In the invention of claim 3,
When the supply oil passage and the discharge oil passage are arranged before and after the cylinder in the air-cooled engine, the cooling unevenness is particularly likely to occur, but the oil cooling unevenness can be suppressed as much as possible by the bypass oil passage.

In the invention of claim 4,
Since the bypass oil passage is arranged between the cylinder and C, the portion that forms the side wall of the drive member housing chamber is relatively strong because it is not easily affected by the heat from the cylinder. However, there is no risk of thermal effects and strength reduction.

In the invention of claim 5,
Since the bypass oil passage is provided only in the cylinder block on one side of the drive member housing chamber, the cross-sectional area of the oil passage in the cylinder head connected to the groove on the upper surface of the cylinder block on the other side is reduced, and the oil jackets on both sides are The oil quantity can be balanced.

In the invention of claim 6,
Since bypass oil passages and lubricating oil branch oil passages are formed in the form of grooves in the cylinders on both sides of the drive member storage chamber, multiple oil passages can be processed on the same surface from the same direction when processing the cylinder block, reducing man-hours. And a reduction in strength of the cylinder block can be suppressed due to the groove type.

1 is a side view of a motorcycle equipped with a four-cylinder engine according to an embodiment of the present invention. It is the figure which looked at the longitudinal cross-section of the said engine from the right side. It is the figure which looked at the longitudinal cross-section of the engine principal part containing the cam chain chamber of the said engine from the right side. It is the figure which looked at the air cooling type oil cooler of FIG. 2 from the front. It is a front view of a cylinder block center part. It is VI-VI sectional drawing of FIG. It is a top view of a cylinder block. It is a bottom view of a cylinder head. It is a top view of a cylinder head. It is XX sectional drawing of FIG. Top view of oil jacket lid XII-XII sectional view of FIG. It is XIII-XIII sectional drawing of FIG. It is a rear view of a cylinder block. It is a bottom view of a cylinder block. It is a side view of the peripheral part of an oil return piping. It is a top view of a lower crankcase.

  FIG. 1 is a side view of a motorcycle 2 equipped with a four-cylinder engine 1 according to an embodiment of the present invention. Arrow F points forward. The body frame of the motorcycle 2 includes a head pipe 3, a main frame 4 extending obliquely rearward from the head pipe 3, a center frame 5 extending downward from the rear end of the main frame 4, the head pipe 3 and the main frame 4. An auxiliary frame 6 that connects the frames 4, a down frame 7 that extends downward from the auxiliary frame 6, a seat stay 8 that extends backward from the main frame 4, and a midline that connects the center of the center frame 5 and the center of the seat stay 8. And a frame 9. A front fork 11 that supports the front wheel 10 is supported by the head pipe 3 so as to be steerable. A steering handle 12 is connected to the front fork 11. A rear fork 14 that supports the rear wheel 13 is supported on the rear portion of the center frame 5 so as to swing up and down, and a cushion unit 15 is provided between the connection portion between the seat stay 8 and the mid frame 9 and the rear fork 14. Is provided. The engine 1 is supported by the down frame 7, the main frame 4, and the center frame 5, and the power of the engine 1 is transmitted to the rear wheel 13 via the rear wheel drive chain 16. A fuel tank 17 is provided on the main frame 4 so as to be positioned above the engine 1, and a tandem seat 18 for a driver and a passenger is mounted on the seat stay 8. An exhaust pipe 19 extends from the engine 1, bends downward, extends rearward, and is connected to a rear muffler 20. An air-cooled oil cooler 21 is provided in the down frame 7 in front of the engine 1.

  FIG. 2 is a view of the longitudinal section of the engine 1 as viewed from the right. The engine 1 is an air-cooled four-cylinder DOHC wet sump engine, and a cooling system oil circuit is shown in the figure. The cylinder 24 in this figure shows a II-II cross section in FIG. The arrow F points to the front corresponding to the front of the vehicle when the engine is mounted on the vehicle. In this engine, an internal combustion engine 25 and a transmission 26 are integrated. The outer shell of the engine 1 includes a crankcase 27 composed of an upper crankcase 27A and a lower crankcase 27B, a cylinder block 28, a cylinder head 29, a cylinder head cover 30, and an oil pan 31. A crankshaft 32, a transmission main shaft 33, and a countershaft 34 are rotatably supported by bearings on a mating surface of the crankcase 27 that is divided into two vertically.

  The cylinder block 28 has four cylinders, and a piston 35 is slidably accommodated in each cylinder 24 and connected to the crankshaft 32 via a connecting rod 36. A combustion chamber 37 is provided below the cylinder head 29 facing the upper surface of each piston 35. Spark plugs 38 are inserted from above the cylinder head 29 toward the combustion chambers 37, respectively, and their tips face the combustion chambers 37. The cylinder head 29 is provided with an intake port 39 and an exhaust port 40 connected to each combustion chamber 37, and an inner end thereof opens to the combustion chamber 37. At the inner end openings of the intake port 39 and the exhaust port 40, an intake valve 41 and an exhaust valve 42 for opening and closing the respective openings are provided. A valve operating mechanism 45 including an intake cam shaft 43 and an exhaust cam shaft 44 is provided on the mating surface of the cylinder head 29 and the cylinder head cover 30.

  An oil pan 31 having a shallow bottom portion and a deep bottom portion is connected to the lower portion of the lower crankcase 27B. An oil suction pipe 47 having a strainer 46 is provided at the deep bottom portion of the oil pan 31, and an oil pump 48 is connected to the upper portion thereof. The oil pump 48 includes a cooling system oil pump and a lubrication system oil pump, and is connected to the same oil pump shaft.

  The engine 1 is provided with a cooling system oil circuit and a lubrication system oil circuit independently. Each oil circuit is supplied with oil separately from the cooling system oil pump and the lubrication system oil pump. FIG. 2 shows the cooling system oil pump 48 and the cooling system oil circuit, and the illustration of the lubricating system oil pump and the lubricating system oil circuit is omitted. Since the present invention is limited to those related to the cooling system, in the following description, the cooling system oil pump 48 and the cooling system oil circuit will be simply referred to as the oil pump 48 and the oil circuit.

  The details of the oil passage will be described later. First, the overall configuration of the oil passage will be described. In the oil circuit of FIG. 2, a discharge pipe A1 connected to the oil pump 48 extends forward in the oil pan and bends upward to reach an oil cooler connecting portion 49 at the lower front of the lower crankcase 27B. An oil cooler forward pipe A2 is connected to the oil cooler connecting portion 49, and is connected to the air-cooled oil cooler 21 at the upper front of the engine. The oil cooled here is sent to the oil introduction part 50 at the lower front of the cylinder block 28 via the oil cooler return pipe A3. The oil introduction part 50 is connected to the supply side oil gallery A4.

  The valve drive member includes a cam chain and a timing belt, but the cam chain 51 (see FIG. 3) is used in the engine 1 of the present embodiment. Therefore, in the following description, the valve drive member housing chamber is used. Is called the cam chain chamber 52. When this engine is mounted on a vehicle, it is a parallel 4-cylinder engine in which four cylinders 24 are arranged in the left-right direction (see FIG. 7). Since the cam chain chamber 52 is provided at the center, Two are grouped together. In the supply side oil gallery A4, the oil passage is divided into right and left, and is connected to the cylinder block rising oil passage A5 directed to the left and right blocks. The upper part of the cylinder block rising oil passage A5 is connected to the cylinder block upper surface distribution groove A6 for the left and right blocks. On the lower surface of the cylinder head 29 covering the upper part of the distribution groove A6, the lower end of the cylinder head supply oil passage A7 provided independently for each cylinder is opened so as to communicate with the distribution groove A6. The upper end of the cylinder head supply oil passage A7 communicates with the spark plug oil jacket A8, and the periphery of the spark plug 38 is cooled by the supplied oil.

  The spark plug oil jacket A8 is connected to the cylinder head oil discharge oil passage A9 provided for each cylinder on the rear side of the cylinder 24. The lower end of the oil discharge oil passage A9 in the cylinder head opens into a cylinder block upper surface collection groove A10 for the left and right blocks. The cylinder block upper surface collection groove A10 is connected to a discharge side oil gallery A12 provided at the lower portion of the cylinder block 28 by a cylinder block lowering oil passage A11 for each of the left and right blocks. Since the discharge side oil gallery A12 extends over the left and right blocks, the cylinder block descending oil passage A11 for each of the left and right blocks is combined into one, and is connected to the crankcase discharge oil passage A13 via the discharge connecting portion 53. It is a series. An oil return pipe A14 is connected to the lower end of the crankcase discharge oil passage A13 and opens above the oil pan 31.

  FIG. 3 is a view of a longitudinal section of the engine 1 including the cam chain chamber 52 as viewed from the right side. The cam chain chamber 52 is provided at a substantially central portion in the left-right direction of the engine 1. The cam chain chamber 52 in this figure shows a III-III cross section in FIG. In FIG. 3, an intake cam shaft 43 and an exhaust cam shaft 44 are rotatably supported on mating surfaces of a cylinder head 29 and a cylinder head cover 30, and a cam shaft driven sprocket 56 is provided on each shaft. The crankshaft 32 supported by the mating surfaces of the upper and lower crankcases 27A and 27B is provided with a camshaft drive sprocket 57 having a half diameter of the camshaft driven sprocket 56. The cam chain 51 is wound around these sprockets, and the intake cam shaft 43 and the exhaust cam shaft 44 rotate according to the rotation of the crankshaft 32.

  The crankshaft 32 rotates in the direction of arrow W. A cam chain guide is provided around the cam chain 51. The upper part between the two driven sprockets is a fixed upper cam chain guide 58, and the cam chain 51 on the front side of the cam chain chamber 52 is fixed on the rear side of the cam chain chamber 52. The cam chain 51 on the feeding side is provided with a oscillating cam chain guide 60. The swing cam chain guide 60 swings around the lower end bolt 61. A cam chain tensioner 63 is provided on the cam chain tensioner mounting portion 62 on the rear wall of the cylinder block 28, and the swinging cam chain guide 60 is pushed by the projecting shaft 63a to prevent the cam chain 51 from slackening.

  FIG. 4 is a front view of the air-cooled oil cooler 21 of FIG. In the drawing, left and right are indicated by arrows L and R corresponding to the left and right sides of the vehicle when the engine 1 is mounted on the vehicle. The same applies to the other drawings described below. The upper end of the oil cooler outgoing pipe A2 is connected to the right side of the oil cooler 21, and the flange 66 of the outgoing pipe at the lower end is connected to the oil cooler connecting part 49 at the front of the lower crankcase (FIG. 2). . The upper end of the oil cooler return pipe A3 is connected to the left side of the oil cooler 21, and the flange 67 of the return pipe at the lower end is connected to the oil introduction part 50 at the front of the cylinder block 28 (FIG. 2).

  FIG. 5 is a front view of the central portion of the cylinder block 28. In the drawing, the upper side of the engine corresponding to the upper side of the vehicle is indicated by an arrow Up together with left and right L and R when the engine 1 is mounted on the vehicle. The same applies to the other drawings described below. In the figure, an oil introduction portion 50 is provided at the lower front portion of the cylinder block 28. Here, the flange portion 67 (FIG. 4) of the return pipe at the lower end of the oil cooler return pipe A3 is connected. The oil introduction part 50 communicates with the supply side oil gallery A4. Cylinder block rising oil passages A5 stand up from both ends of the supply side oil gallery A4. This cylinder block 28 is provided with a cam chain chamber 52 at the center in the left-right direction, and the cylinders are separated into two left and right, so that oil is supplied to the supply side oil gallery A4 in order to send oil to the left and right blocks. It is distributed to the left and right through. The upper end of the cylinder block rising oil passage A5 is connected to the cylinder block upper surface distribution groove A6.

  6 is a cross-sectional view taken along the line VI-VI in FIG. 5 and is a vertical cross-sectional view of the cylinder block 28 including the cylinder block rising oil passage A5. The lower part of the cylinder block rising oil passage A5 communicates with the supply side oil gallery A4, and the upper part of the cylinder block rising oil path A5 communicates with the cylinder block upper surface distribution groove A6. The figure also shows the cylinder block upper surface recovery groove A10 and the discharge side oil gallery A12.

  FIG. 7 is a top view of the cylinder block 28. Since the cam chain chamber 52 is opened at the center in the left-right direction of the cylinder block 28, the cylinder 24 is divided into two on the left and right. In the engine 1, the upper crankcase 27A and the cylinder block 28 are integrally coupled by a stud bolt. A plurality of stud bolt insertion holes 68 can be seen in the figure. On the upper surface of the cylinder block 28, distribution grooves A6 are provided on both sides of the cam chain chamber 52, respectively. Recovery grooves A10 are also provided on both sides of the cam chain chamber 52, respectively. All of these grooves are provided outside the stud bolt insertion hole 68 so as to be curved. The upper ends of the cylinder block ascending oil passages A5 are opened at positions where the left and right distribution grooves A6 of the cam chain chamber 52 are marked m1 and m2 near the respective cam chain chambers 52. The upper ends of the in-cylinder block descending oil passages A11 are opened at the positions of the left and right recovery grooves A10 of the cam chain chamber 52 where the reference numerals n1 and n2 are attached.

  FIG. 8 is a bottom view of the cylinder head 29. A cam chain chamber 52 is opened at the center in the left-right direction. In each combustion chamber 37 corresponding to each cylinder 24 in FIG. 7, an ignition plug insertion hole 69, an inner end 39a of each of the two intake ports 39, and an inner end 40a of the exhaust port 40 are opened. These openings are provided with a spark plug 38, an intake valve 41, and an exhaust valve 42 shown in FIG. The front and rear flat portions of the combustion chamber 37 serve as a lid that covers the upper surfaces of the cylinder block upper surface distribution groove A6 and the cylinder block upper surface recovery groove A10 in FIG.

  In the front and back plane portions of the combustion chamber 37, lower ends of a cylinder head supply oil passage A7 and a cylinder head oil discharge oil passage A9 shown in FIG. In FIG. 7, the lower end of the cylinder head supply oil passage A7 opens at a position of the cylinder block upper surface distribution groove A6 with the reference numerals f1, f2, f3, and f4. In FIG. 7, the lower end of the cylinder head oil discharge oil passage A9 opens at a position marked with reference numerals g1, g2, g3, and g4 of the cylinder block upper surface recovery groove A10. Oil is supplied from the cylinder block upper surface distribution groove A6 to the cylinder head supply oil passage A7. Further, the oil is discharged from the cylinder head oil discharge oil passage A9 to the cylinder block upper surface collection groove A10.

  FIG. 9 is a top view of the cylinder head 29. A cam chain chamber 52 is opened at the center. Two spark plug insertion holes 69 are provided on the left and right sides of the cylinder head. Two intake valve mounting holes 70 are provided on the rear side of each spark plug insertion hole 69. Two exhaust valve mounting holes 71 are provided on the front side of each spark plug insertion hole 69. A bearing portion 84 of the intake cam shaft 43 is provided between each pair of intake valve mounting holes 70, and a bearing portion 85 of the exhaust cam shaft 44 is provided between each pair of exhaust valve mounting holes 71.

  A spark plug oil jacket A8 is provided around each spark plug insertion hole 69. The spark plug oil jacket A8 is connected to the cylinder head supply oil passage A7 and the cylinder head oil discharge oil passage A9. The upper part of the spark plug oil jacket A8 is covered with an oil jacket lid member 72 shown in FIGS.

  FIG. 10 is a cross-sectional view taken along the line XX in FIG. 9 and is a vertical cross-sectional view of the cylinder head 29 including the spark plug insertion hole 69. An oil jacket A8 is provided around the spark plug insertion hole 69. The oil jacket A8 is an annular groove (see FIG. 9), and the periphery of the spark plug 38 (FIG. 2) is cooled by the supplied oil. The upper end of the cylinder head supply oil passage A7 reaches the front side of the spark plug oil jacket A8. The rear side of the spark plug oil jacket A8 is connected to the cylinder head oil discharge oil passage A9, and the cooled oil around the spark plug 38 is discharged to the cylinder head oil discharge oil passage A9. The upper portion of the spark plug oil jacket A8 is covered with an oil jacket lid member 72.

  11 to 13 are three views of the oil jacket lid member 72, FIG. 11 is a top view, FIG. 12 is a sectional view taken along line XII-XII in FIG. 11, and FIG. 13 is a sectional view taken along line XIII-XIII in FIG. In this engine 1, the valve mechanism 45 is covered with the cylinder head cover 30 (FIGS. 2 and 3), but the upper part of the spark plug 38 is not covered with the cylinder head cover 30. Touch the air flow. A lid member cooling fin 73 is provided on the upper surface of the oil jacket lid member 72 and serves to cool the periphery of the spark plug 38. Further, as described above, since the spark plug 38 is exposed to the outside air, water may enter the periphery of the spark plug 38. Therefore, a drain hole 74 is provided in the oil jacket lid member 72. The oil jacket lid member 72 is provided with a pair of mounting screw hole insertion holes 72a.

  In the upper surface of the cylinder block 28 on the right side of the cam chain chamber 52 in FIG. 7, the cylinder is attached to the cylinder block upper surface distribution groove A6 from the portion adjacent to the upper end opening position m2 of the cylinder block rising oil passage A5 by the symbol s. A bypass groove B1 is formed so as to reach a portion denoted by reference numeral g3 in the block upper surface recovery groove A10. The upper end opening position m2 of the cylinder block rising oil passage A5 and the start point s of the bypass groove B1 communicate with each other by a bypass groove B2 formed on the lower surface of the cylinder head in FIG. When the upper surface of the cylinder block 28 is covered by the lower surface of the cylinder head 29, the bypass oil passage that short-circuits the cylinder block upper surface distribution groove A6 and the cylinder block upper surface recovery groove A10 without passing through the oil jacket A8 by the bypass grooves B1 and B2 B is formed. This is because the cooled oil that has risen from the rising oil passage A5 in the cylinder block and the high-temperature oil that has passed through the oil jacket A8 are merged in the cylinder block upper surface collection groove A10, so that the front side and the rear side of the cylinder block 28 are combined. In order to eliminate the uneven cooling in the cylinder block 28. A lubricating oil distribution groove 75 that distributes lubricating oil that lubricates each part of the valve operating mechanism 45 is formed in a groove form on the opposite side of the bypass oil passage with the cam chain chamber 52 interposed therebetween, that is, on the upper surface of the left cylinder block 28. Is formed.

  FIG. 14 is a rear view of the cylinder block 28. The left and right cylinder block upper surface collection grooves A10 shown in FIG. 7 are also shown in FIG. A cylinder block descending oil passage A11 extends downward from the middle of each of the left and right collection grooves A10. The pair of descending oil passages A11 in the cylinder block reaches the discharge side oil gallery A12 at the lower part of the cylinder block and merges there. In the middle of the discharge-side oil gallery A12, a discharge connection portion 53 is provided slightly to the left of the center, and the discharge-side oil gallery A12 communicates with the crankcase discharge oil passage A13 through this. In the drawing, a tensioner mounting portion 62 is provided at the center of the rear surface of the cylinder block 28.

  FIG. 15 is a bottom view of the cylinder block 28. A discharge connecting portion 53 for connecting the oil passage to the crankcase discharge oil passage A13 is opened slightly on the left side of the middle of the discharge side oil gallery A12 on the rear surface side of the cylinder block 28. In this figure, the supply side oil gallery A4 and the oil introduction part 50 are also shown.

  FIG. 16 is a side view of the peripheral portion of the oil return pipe A14. The discharge connection portion 53 communicates with the upper end of the crankcase discharge oil passage A13 provided at the upper portion of the upper crankcase 27A. The crankcase discharge oil passage A13 is a short oil passage. The upper end of the oil return pipe A14 is inserted into the lower end of the crankcase discharge oil path A13 via a seal member 82, and the middle part of the oil return pipe A14 is attached to and detached from the oil pump 48 via a support member 80. It is fixed as possible. The lower portion of the oil return pipe A14 extends to the vicinity of the lower end surface of the lower crankcase 27B, but does not protrude below the lower end surface of the lower crankcase 27B. The lower end of the oil return pipe A14 is opened toward the oil pan 31. FIG. 16 shows a locus 79a of the maximum outer circumference of the crank web 78 (FIG. 2). The oil return pipe A14 overlaps the locus 79 of the crank web 78 in a side view.

  FIG. 17 is a top view of the lower crankcase 27B. A bottom plate 27Ba is provided on the left and right end portions of the lower crankcase 27B and the lower surface of the front edge portion. The lower surface of the central portion is a lower opening 27Bb for connection to an oil pan. In the figure, the crankshaft 32 supported by the bearing 83 is shown in cross section. The oil return pipe A14 is passed through a narrow space between the side wall of the cam chain chamber 52, the crank web 78, and the oil pump 48, and is supported by the oil pump 48 via a support member 80.

  In the oil passage described above, the cylinder head cooling oil sent from the oil pan 31 via the oil pump 48 is the discharge pipe A1, the oil cooler forward pipe A2, the oil cooler return pipe A3, the supply side oil gallery A4, the cylinder. Ascending oil passage A5, Cylinder block upper surface distribution groove A6, Cylinder head supply oil passage A7, Spark plug oil jacket A8, Cylinder head oil discharge oil passage A9, Cylinder block upper surface recovery groove A10, Cylinder block lowering oil passage The cylinder head 29 is cooled by returning to the oil pan 31 via A11, the discharge side oil gallery A12, the crankcase discharge oil passage A13, and the oil return pipe A14. In this circulation path, a part of the oil flows through the bypass grooves B1 and B2 without passing through the spark plug oil jacket A8, thereby eliminating the uneven cooling of the cylinder block 28.

  7 and 8, there is a bypass oil passage B (comprising bypass grooves B1 and B2) that does not pass through the spark plug oil jacket A8 and short-circuits between the cylinder block upper surface distribution groove A6 and the cylinder block upper surface collection groove A10. It is provided on the upper surface of the cylinder block 28 and the lower surface of the cylinder head 29. By introducing a part of the introduced oil directly from the distribution groove A6 to the collection groove A10 without passing through the oil jacket A8, the hot oil that has passed through the oil jacket A8 joins with the oil that is not heated by the oil jacket A8. As a result, the oil temperature in the discharge oil passage passing through the cylinder block 28 is lowered, the temperature difference between the oil on the front side and the rear side of the cylinder block 28 is reduced, and the uneven cooling on the front and rear surfaces of the cylinder block 28 is reduced. ing.

  7 and 8, the bypass oil passage B is formed by a groove B1 formed on the upper surface of the cylinder block 28, a bypass groove B2 for communication formed on the lower surface of the cylinder head 29, and a lower surface of the cylinder head 29 serving as a lid for the groove B1. It is configured. This is because the configuration of the bypass oil passage B can be simplified, the processing can be simplified, and the processing cost can be reduced as compared with the case where the bypass oil passage B is formed in the cylinder block by the through machining. .

  The engine 1 of the present embodiment is an air-cooled engine in which air-cooled fins are provided in a cylinder block 28, and an ascending oil passage A5 is disposed on the front side of the cylinder with respect to the vehicle traveling direction (FIG. 5). The path A11 is disposed on the rear side of the cylinder (FIG. 14). In such an arrangement, the front surface of the cylinder block is cooled by the traveling wind, and the rear surface of the cylinder block is heated by the discharged oil via the cylinder head, so that uneven cooling of the cylinder block is likely to occur. Bypass oil passage B makes it possible to suppress uneven cooling due to oil as much as possible.

  In FIG. 7, a bypass groove B1 is disposed on the upper surface of the cylinder block 28 between the cam chain chamber 52 and the cylinder 24 adjacent thereto. Since the bypass groove B1 is arranged between the cylinder 24 and the cam chain chamber 52, the bypass groove is less affected by heat from the cylinder and the portion forming the side wall of the cam chain chamber 52 is relatively strong. Even if B1 is arranged, there is no fear of heat influence and strength reduction.

  The bypass oil passage B is disposed only in the cylinder block on one side (right side) with the cam chain chamber 52 interposed therebetween. Although it is necessary to supply a large amount of oil to the side where the bypass oil passage B is located, the bypass oil passage is not arranged in the cylinder block on the other side (left side) sandwiching the cam chain chamber 52. The flow rate is not large. Therefore, the cylinder block rising oil passage A5 connected to the cylinder block upper surface distribution groove A6 on one side (right side) sandwiching the cam chain chamber 52, and the cylinder block falling oil connected to the cylinder block upper surface collection groove A10 The cross-sectional area of the passage A11 is increased, and the cylinder block upper oil passage A5 connected to the cylinder block upper surface distribution groove A6 on the other side (left side) across the cam chain chamber 52 and the cylinder block upper surface recovery groove A10 are connected. The cross-sectional area of the cylinder block descending oil passage A11 is reduced to balance the oil amount in the cylinder blocks on both sides (not shown). This makes it possible to equalize the amount of oil supplied to the oil jacket A8 around the spark plug.

  In FIG. 7, the bypass oil passage is formed by forming a groove B1 on the upper surface of the cylinder block. Further, the valve system is lubricated on the upper surface of the cylinder block opposite to the bypass groove B1 with the cam chain chamber 52 interposed therebetween. A lubricating oil distribution groove 75 that branches the lubricating oil is formed. Since the bypass groove B1 and the lubricating oil distribution groove 75 are formed in the cylinders on both sides of the cam chain chamber 52, a plurality of passages can be processed on the same surface from the same direction when the cylinder block is processed. Moreover, the strength reduction of the cylinder block can be suppressed by the groove type.

  A5 ... Cylinder block rising oil passage, A6 ... Cylinder block upper surface distribution groove, A7 ... Cylinder head supply oil passage, A8 ... Oil jacket around spark plug, A9 ... Cylinder head discharge oil passage, A10 ... Cylinder block upper surface recovery Groove, A11 ... Cylinder block descending oil passage, B ... Bypass oil passage (consisting of B1 and B2), B1 ... Bypass groove, B2 ... Communication bypass groove, 28 ... Cylinder block, 29 ... Cylinder head, 52 ... Cam Chain chamber, 75 ... Lubrication oil distribution groove, 81 ... Cylinder block cooling fin

Claims (6)

  A multi-cylinder engine (1) in which supply oil passages (A5, A7) and discharge oil passages (A9, A11) connecting the cylinder block (28) to the spark plug oil jacket (A8) of the cylinder head (29) are formed. In the cylinder head cooling oil passage, a bypass oil passage (B1, B2) that does not pass through the spark plug oil jacket (A8) is provided in the cylinder block (28). Cylinder head cooling oil passage.   The bypass oil passage (B1, B2) is constituted by a groove (B1) formed on an upper surface of a cylinder block (28) and a lower surface of a cylinder head (29) closing the upper portion thereof. 2. An oil passage for cooling a cylinder head of the multi-cylinder engine according to 1. The multi-cylinder engine (1) is an air-cooled engine (1) in which air-cooled fins (81) are provided on a cylinder block (28).
When the multi-cylinder engine (1) is mounted on the vehicle (2), the supply oil passages (A5, A7) are provided on the front side of the cylinder (24) with respect to the vehicle traveling direction, the oil discharge passage (A9, A11) is a cylinder head cooling oil passage for a multi-cylinder engine according to claim 1 or claim 2, characterized in that it is provided so as to be positioned on the rear side of the cylinder (24). A parallel multi-cylinder engine (1) having cylinders (24) on both sides of a drive member storage chamber (52) that stores a valve drive member (51), and bypass oil passages (B1, B2) are provided. the drive member storage chamber (52), multi according to any one of claims 1 to 3, characterized in that arranged in the cylinder block (28) between the cylinder (24) adjacent thereto Cylinder head cooling oil passage for cylinder engine.   The bypass oil passages (B1, B2) are disposed only in one cylinder (24) with the drive member storage chamber (52) interposed therebetween, and in the other cylinder (24) with the drive member storage chamber (52) interposed therebetween. Shows the cross-sectional areas of the supply oil passage (A5) and the discharge oil passage (A11) connected to the groove (A1) formed on the upper surface of the cylinder block, the supply oil passage (A5) on one side and the discharge oil. 5. The oil passage for cooling a cylinder head of a multi-cylinder engine according to claim 4, wherein the oil passage is smaller than a cross-sectional area of the passage (A11).   The bypass oil passage (B1, B2) is formed by forming a groove (B1) on the upper surface of the cylinder block, and further on the opposite side of the bypass oil passage (B1, B2) with the drive member housing chamber (52) interposed therebetween. 6. The multiple oil passage according to claim 4 or 5, wherein a branch oil passage (75) for branching the lubricating oil for lubricating the valve train (45) is formed on the upper surface of the cylinder block (28) in the form of a groove. Cylinder head cooling oil passage for the cylinder engine (1).

Images