JP6061368B2 - Structure of cylinder head for water-cooled internal combustion engine - Google Patents

Description

  The present invention relates to a structure of a cylinder head for a water-cooled internal combustion engine, and more particularly to a structure of a cooling water passage provided in the cylinder head.

  2. Description of the Related Art Conventionally, for example, an internal combustion engine used for a vehicle such as a motorcycle generally employs a method of cooling the inside using cooling water (so-called “water cooling type”).

  In this water-cooled internal combustion engine, cooling water passages communicating with each other are provided in the cylinder and the cylinder head. The cooling water introduced into the cooling water passage from the inlet provided on the cylinder side passes through the cooling water passage and is discharged from the outlet provided on the cylinder head side. It is configured to be cooled. As such a water-cooled internal combustion engine, Patent Document 1 discloses a configuration in which an outlet of a cooling water passage is provided on one side wall of a cylinder head perpendicular to a deck surface (joint surface with a cylinder) (patent). (See FIG. 4 of Document 1).

  Further, in an internal combustion engine of a system in which camshafts are supported on the intake side and exhaust side of the cylinder head (so-called “DOHC type”), when machining the bearing portion of each camshaft into the cylinder head, the machining accuracy is high. For the purpose of improvement and the like, a pair of half-moon shaped recesses are provided on both side walls of the cylinder head. Therefore, in the DOHC type internal combustion engine, when the outlet of the cooling water passage is provided on one side wall of the cylinder head as in Patent Document 1, the pair of recesses is avoided so as to avoid the pair of recesses. The outlet of the cooling water passage is provided, or the outlet of the cooling water passage is provided so as to protrude outward from one side wall.

JP-A-9-170416

  However, as in the case of Patent Document 1, in the configuration in which the outlet of the cooling water passage is provided on one side wall of the cylinder head perpendicular to the deck surface, when the outlet hose is connected to this outlet, the side wall of the cylinder head is substantially omitted. The outlet hose will be installed at right angles. Therefore, the outlet hose protrudes greatly to the outside of one side wall, resulting in a problem that the width of the entire internal combustion engine is increased.

  In the above-described configuration in which the outlet of the cooling water passage is disposed between the pair of recesses in the DOHC type internal combustion engine, the width of the cooling water passage can be sufficiently secured when the interval between the pair of recesses is narrow. It was difficult. Further, in the DOHC type internal combustion engine, in the configuration in which the outlet of the cooling water passage extends from one side wall, the width of the cylinder head is increased correspondingly, and accordingly, as in the case of Patent Document 1, the width of the entire internal combustion engine is increased. There has been a problem of growing.

  In view of the above circumstances, an object of the present invention is to suppress an increase in the width of the cylinder head and reduce the overall width of the engine while ensuring a sufficient cross-sectional area of the cooling water passage.

The present invention is a structure of a cylinder head for a water-cooled internal combustion engine used in a motorcycle, in which a deck surface joined to a cylinder is provided at a lower end and a cooling water passage for allowing cooling water to pass therethrough is provided therein. The outlet of the cooling water passage is provided on one side wall side, the outlet is formed horizontally along the one side wall, and is provided obliquely upward with respect to the deck surface. At the upper end of the cylinder head, Cam journal receiving portions for supporting the cam journal of the camshaft are provided on the front exhaust side and the rear intake side, respectively , and a flange portion to which an outlet hose can be joined is provided around the outlet. is viewed in the axial direction of the camshaft, is formed so as to overlap with the cam journal receiving portion of the front exhaust side only, the flange portion, et provided at an upper end portion of said one side wall Characterized in that the motorcycle main frame in a space formed on the lower side of the flange portion is disposed.

  As described above, since the outlet of the cooling water passage is provided obliquely upward with respect to the deck surface, when the outlet hose is joined around the outlet, the outlet hose can be attached to the one side wall obliquely from above. It becomes possible. Therefore, compared with the case where the outlet hose is mounted perpendicularly to one side wall, it becomes possible to reduce the width necessary for arranging the outlet hose, and accordingly, the width of the entire engine is also reduced. Is possible.

In addition, by forming the outlet of the cooling water passage in a horizontally long shape along the one side wall, the width of the cooling water passage protruding from the outer surface of the one side wall is reduced while sufficiently securing the cross-sectional area of the cooling water passage. It becomes possible. For this reason, the width of the cylinder head can be reduced, and accordingly, the width of the entire engine can be further reduced. Moreover, it becomes possible to provide a flange part in the upper end part of one side wall, and the effective utilization of the space below a flange part is attained.

A recess for processing the cam journal receiving portion is provided on the same axis as the cam journal receiving portion at an upper edge portion of the side wall opposite to the one side wall of the cylinder head. Is processed from only one side, and the recess may not be formed in the upper edge of the one side wall of the cylinder head.

  Furthermore, a joining flange may be provided on the outer periphery of the upper end of the cylinder head, and the joining flange and at least a part of the flange portion may be provided at the same height from the deck surface.

  By adopting such a configuration, the flange portion can be disposed at a position as far as possible from the deck surface, and the space between the flange portion and the deck surface can be effectively used.

  Furthermore, an offset portion is provided inward on the one side wall, and the flange portion is formed on the offset portion, so that at least a part of the flange portion is more than the outermost edge portion of the one side wall. You may arrange | position inside.

  By adopting such a configuration, it becomes possible to provide the flange portion on the inner side, and it is possible to reduce the width at which the flange portion protrudes from the outer surface of the one side wall.

  The outlet hose may be provided above a cylinder head cover that covers an upper surface of the cylinder head.

  By adopting such a configuration, the outlet hose can be easily disposed even when a member around the cylinder head and one side wall are close to each other.

  Furthermore, the cylinder head is provided with a plug cylinder portion in which a plug hole is formed perpendicular to the deck surface, and is inclined downstream from the root side of the plug hole toward the downstream side of the cooling water passage. An end may be formed in a straight line, and the outlet may be connected to the downstream end.

  By adopting such a configuration, it is possible to reduce the flow resistance of the cooling water in the cooling water passage.

  According to the present invention, it is possible to suppress an increase in the width of the cylinder head while reducing a width of the entire engine while ensuring a sufficient cross-sectional area of the cooling water passage.

1 is a perspective view from the front lower side showing the positional relationship between a main body frame and an engine in a motorcycle according to an embodiment of the present invention. 1 is a left side view of an engine in a motorcycle according to an embodiment of the present invention. 1 is a cross-sectional view showing an internal structure of a cylinder head in a motorcycle according to an embodiment of the present invention. 1 is a perspective view from the upper left side showing a cylinder head in a motorcycle according to an embodiment of the present invention. 1 is a perspective view from the left front of a cylinder, a cylinder head, and a cylinder head cover in a motorcycle according to an embodiment of the present invention. 1 is a left side view showing a cylinder head and a cylinder head cover in a motorcycle according to an embodiment of the present invention. 1 is a front view showing a cylinder head and a cylinder head cover in a motorcycle according to an embodiment of the present invention. 1 is a plan view showing a cylinder head and a cylinder head cover in a motorcycle according to an embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where the structure of the present invention is applied to an on-road motorcycle 1 will be described. In addition, the direction seen from the driver | operator who gets on the motorcycle 1 is made into the reference | standard for the up-down, left-right, and front-back direction. An arrow Fr appropriately displayed in each figure indicates the front side of the motorcycle 1.

  First, the overall configuration of the motorcycle 1 will be described.

  As shown in FIG. 1, the motorcycle 1 is provided with a vehicle body frame 2 constituting a framework. The vehicle body frame 2 is, for example, a twin tube type, and includes a head pipe 3 disposed at the front upper end of the vehicle body frame 2 and a pair of left and right main frames 4 extending rearward and downward from the head pipe 3. In addition, an engine 5 is mounted between the main frames 4.

  Although not shown, the head pipe 3 supports a pair of left and right front forks that can rotate left and right, a front wheel is pivotally supported at the lower end of the front fork, and a handlebar is disposed in the left and right direction at the upper end of the front fork. It is fixed. In addition, a pivot shaft is installed at the rear lower part of the pair of left and right main frames 4, and the front end portion of the swing arm is supported on the pivot shaft so as to be swingable in the vertical direction. It is supported.

  Next, an outline of the engine 5 will be described.

  The engine 5 is, for example, a DOHC-type water-cooled parallel four-cylinder engine. As shown in FIG. 2, the upper and lower split crankcase 8 including an upper crankcase 6 and a lower crankcase 7, and an upper crankcase 6. And a cylinder head 11 provided above the cylinder 10 and a cylinder head cover 12 that covers the upper surface of the cylinder head 11.

  A crankshaft 14 is pivotally supported in the crankcase 8 along a split surface between the upper crankcase 6 and the lower crankcase 7, and a transmission 15 is provided behind the crankshaft 14. The transmission 15 is, for example, a six-speed transmission type, and includes an input shaft 16 connected to the crankshaft 14 and an output shaft 17 connected to the input shaft 16. A drive sprocket 18 is supported on the left end portion of the output shaft 17 in a cantilever state.

  Although not shown in the drawings, four cylinder bores are provided for each cylinder, and pistons are accommodated in each cylinder bore so as to be movable up and down. The piston is connected to the crankshaft 14 via a connecting rod.

  As shown in FIG. 2, an intake port 27 is provided on the rear surface of the cylinder head 11 for each cylinder. An intake pipe (not shown) is connected to each intake port 27, and an air-fuel mixture supplied from the intake pipe is connected to a combustion chamber 28 (see FIG. 3) provided for each cylinder via each intake port 27. It is configured to be introduced. An exhaust port 30 is provided on the front surface of the cylinder head 11 for each cylinder. An exhaust pipe 31 is connected to each exhaust port 30, and exhaust gas from the combustion chamber 28 is discharged to the rear of the motorcycle 1 through the exhaust pipe 31 and a muffler (not shown). Yes.

  As shown in FIG. 4, five cam support portions 32 are continuously provided in the cylinder head 11 in the cylinder row direction. Each cam support portion 32 is provided so as to partition the internal space of the cylinder head 11 in the front-rear direction.

  The cam support portion 32 except for the rightmost cam support portion 32 is provided at a position corresponding to each cylinder, and a plug cylinder portion 33 is provided at the center in the front-rear direction. As shown in FIG. 3, the plug cylinder portion 33 is provided perpendicular to the deck surface (joint surface with the cylinder 10) 26 provided at the lower end of the cylinder head 11. Each plug cylinder portion 33 is provided with a plug hole 34 from the upper end of the cylinder head 11 to the combustion chamber 28. Each plug hole 34 is equipped with an ignition plug (not shown), and the mixture introduced into the combustion chamber 28 can be ignited by discharge from the ignition plug.

  As shown in FIG. 4, half-moon-shaped cam journal receiving portions 35a and 35b are recessed in the intake side (rear side) and exhaust side (front side) of the upper edge of each cam support portion 32, respectively. . An intake side camshaft 40 is pivotally supported by the intake side cam journal receiving portion 35a, and an exhaust side camshaft 41 is pivotally supported by the exhaust side cam journal receiving portion 35b. In each figure, only the axial position of each camshaft 40, 41 is displayed. Each camshaft 40, 41 is provided with a cam journal (not shown) at a position corresponding to each cam journal receiving portion 35a, 35b, and this cam journal is pivotally supported by the cam journal receiving portions 35a, 35b. ing.

  On the upper edge of the right side wall 36 of the cylinder head 11, a half-moon-shaped recess 37 is provided on the same axis as the cam journal receiving portions 35a and 35b. The concave portion 37 is formed for processing the cam journal receiving portions 35a and 35b. In the present embodiment, the cam journal receiving portions 35a and 35b are processed only from one side (right side), and the concave portion 37 is not formed on the upper edge portion of the left side wall 38 of the cylinder head 11.

  A joint flange 42 having a rectangular shape in plan view is provided on the outer periphery of the upper end of the cylinder head 11, and the lower end of the cylinder head cover 12 is joined to the joint flange 42 (see FIG. 5). The cylinder head 11 is provided with oil passages 43 along both front and rear edges of the joining flange 42. The left and right side walls 36 and 38 of the cylinder head 11 are provided with bearing portions 44 for supporting a finger follower shaft (not shown) on both the front and rear sides of the upper part. The left side wall 38 of the cylinder head 11 is provided further outward than the outermost bolt hole 39 among the bolt holes 39 through which the bolts 29 (see FIG. 2) connecting the cylinder head 11 and the cylinder 10 are inserted. Yes.

  Next, the configuration of the cooling water passage 20 provided in the engine 5 will be described.

  As shown in FIG. 5, an inlet 22 of the cooling water passage 20 is provided at the left end portion of the front surface of the cylinder 10, and an upstream portion 21 of the cooling water passage 20 communicating with the inlet 22 is connected to the left side in the cylinder 10. It is provided from the wall 9 side to the right wall 19 side. As shown in FIG. 2, one end of an inlet hose 23 is connected to the inlet 22, and a radiator 25 provided in front of the engine 5 is connected to the other end of the inlet hose 23. A water pump 24 is provided at an intermediate portion of the inlet hose 23.

  As shown in FIG. 5, a downstream portion 45 of the cooling water passage 20 is provided in the cylinder head 11 from the right side wall 36 side to the left side wall 38 side. The right side wall 36 side of the downstream part 45 is connected to the right wall 19 side of the upstream part 21 provided in the cylinder 10 in the vertical direction. A downstream end 48 is formed at the left end of the downstream portion 45, and an outlet 51 provided on the left side wall 38 side of the cylinder head 11 is connected to the downstream end 48.

  As best shown in FIG. 3, the downstream end portion 48 is linearly provided from the root side of the plug hole 34 closest to the left side wall 38 obliquely upward. The downstream end 48 is covered with an inclined wall 49. The lower right end portion of the inclined wall 49 is connected to the lower end portion of the plug cylinder portion 33 closest to the left side wall 38, and the upper left end portion of the inclined wall 49 is connected to the inner portion of the upper end portion of the left side wall 38. .

  The outlet 51 is formed in a horizontally long oval shape along the left side wall 38, and is provided obliquely upward with respect to the deck surface 26 of the cylinder head 11. Here, “diagonally upward with respect to the deck surface 26” means that the deck surface 26 is inclined upward relative to the deck surface 26 when the deck surface 26 is used as a reference surface. In the state of being mounted on, it does not necessarily have to be obliquely upward with respect to the ground surface.

  A flange portion 50 is provided around the outlet 51. As shown in FIG. 6, the flange portion 50 has an exhaust-side cam journal receiving portion 35 b in the axial direction view of the camshafts 40 and 41 (in this embodiment, the cylinder row direction view and the vehicle width direction view). They are formed so as to overlap (see FIG. 6). A flange surface 52 is formed at the tip of the flange portion 50, and bolt holes 53 are provided on both front and rear sides of the flange surface 52.

  As best shown in FIG. 7, an outlet pipe 54 is joined to the flange portion 50. A joint surface 59 is provided at one end of the outlet pipe 54, and insertion holes 60 are formed on both front and rear sides of the joint surface 59. Then, in a state where the flange surface 52 of the flange portion 50 and the joint surface 59 of the outlet pipe 54 are joined, the bolt 55 inserted through the insertion hole 60 is screwed into the bolt hole 53, whereby the outlet pipe 54 is flanged. It is configured to be connected to the portion 50. The outlet pipe 54 passes over the cylinder head cover 12 and extends to the exhaust side (front side in the present embodiment), and the other end is connected to the radiator 25 (see FIG. 2).

  As shown in FIG. 8, the flange portion 50 is formed in an offset portion 56 provided on the left side wall 38 toward the inside. Thereby, the inner side part 57 of the flange part 50 is arrange | positioned inside the outermost edge part 58 of the left side wall 38 (refer the dashed-two dotted line X of FIG. 8). The inner portion 57 of the flange portion 50 and the joining flange 42 are provided at the same height from the deck surface 26 (see FIG. 6).

  In the configuration as described above, in order to cool the inside of the engine 5 using the cooling water when the motorcycle 1 is traveling, the water pump 24 is operated to cool the cooling water in the radiator 25 from the inlet 22. It flows into the upstream portion 21 of the water passage 20. The cooling water flowing into the upstream portion 21 passes through the cylinder 10 from the left wall 9 side to the right wall 19 side, and cools the inside of the cylinder 10. Thereafter, the cooling water rises to the downstream portion 45 provided in the cylinder head 11, and the downstream portion 45 flows from the right side wall 36 side to the left side wall 38 side to cool the inside of the cylinder head 11. . Then, it flows in the downstream end portion 48 of the cooling water passage 20 obliquely upward and flows into the outlet pipe 54 from the outlet 51. After that, it returns from the outlet pipe 54 to the radiator 25, passes through the radiator 25, is cooled by the traveling wind, and is again introduced into the cooling water passage 20 through the inlet hose 23. By adopting such a cooling method, all the four cylinders arranged in parallel can be uniformly cooled.

  In the present embodiment, since the outlet 51 is provided obliquely upward with respect to the deck surface 26, when the outlet pipe 54 is joined to the flange portion 50, the outlet pipe 54 is obliquely above the left wall 38. It becomes possible to attach from. Therefore, it is possible to reduce the width in the cylinder row direction necessary for arranging the outlet pipe 54, and accordingly further reduce the width in the cylinder row direction of the entire engine 5 and the vehicle width of the motorcycle 1. It becomes possible.

  In addition, since the outlet 51 of the cooling water passage 20 is formed in a horizontally long oval shape along the left side wall 38, the cooling water passage 20 is compared with the case where the outlet 51 of the cooling water passage 20 is made into a perfect circle. It is possible to reduce the width of the cooling water passage 20 in the cylinder row direction (left and right width in the present embodiment) while increasing the horizontal width of 20 (front and rear width in the present embodiment). Thereby, it is possible to reduce the width of the outlet 51 projecting from the left side wall 38 in the cylinder row direction while sufficiently securing the cross-sectional area of the cooling water passage 20 and enhancing the cooling effect of the cylinder head 11 by the cooling water. Become. Therefore, it is possible to reduce the width of the cylinder head 11 in the cylinder row direction, and accordingly, the width of the engine 5 in the cylinder row direction and the width of the motorcycle 1 can be reduced.

  In the present embodiment, as described above, the cam journal receiving portions 35a and 35b are processed only from one side, so that the left side wall 38 is not provided with the concave portion 37. Therefore, it is possible to form the flange portion 50 so as to overlap the exhaust-side cam journal receiving portion 35b when the camshafts 40 and 41 are viewed in the axial direction, and the flange portion 50 can be provided at the upper end portion of the left side wall 38. . Along with this, it is possible to form a large space below the flange portion 50. By disposing the main frame 4 in this large space, the space below the flange portion 50 can be effectively used. (See FIG. 7).

  In the present embodiment, the exhaust-side cam journal receiving portion 35b and the flange portion 50 are configured to overlap with each other when viewed in the axial direction of the camshafts 40 and 41. However, in other different embodiments, The cam journal receiving portion 35a on the side and the flange portion 50 may be configured to overlap each other, or the cam journal receiving portions 35a and 35b on both the intake and exhaust sides may be configured to overlap with the flange portion 50. That is, if the cam journal receiving portions 35a and 35b on either the intake side or the exhaust side are configured to overlap with the flange portion 50, the above-described space is effectively used.

  Further, since the joining flange 42 and the inner portion 57 of the flange portion 50 are provided at the same height from the deck surface 26, the flange portion 50 can be disposed at a position further away from the deck surface 26. A large space can be formed between the flange portion 50 and the deck surface 26. Accordingly, it is possible to further enhance the effect of effectively using the space as described above.

  In the present embodiment, as described above, the flange portion 50 is disposed on the offset portion 56 provided inwardly on the left side wall 38, so that the inner portion 57 of the flange portion 50 is positioned at the outermost edge of the left side wall 38. It arrange | positions inside the part 58 (refer FIG. 8). By adopting such a configuration, the flange portion 50 can be provided on the inner side, and the width in which the flange portion 50 protrudes from the left side wall 38 can be further reduced.

  In the present embodiment, since the outlet pipe 54 is disposed in the space above the cylinder head cover 12, the outlet 50 is coupled with the flange 50 provided at the upper end of the cylinder head 11 as described above. The pipe 54 can be shortened. In addition, since the outlet pipe 54 is provided in the space above the cylinder head cover 12, the outlet pipe 54 can be easily disposed even if the left side wall 38 and the main frame 4 are brought close to each other.

  In addition, the downstream end 48 of the cooling water passage 20 is formed in a straight line from the base side of the plug hole 34 obliquely upward, and the outlet 51 of the cooling water passage 20 is connected to the downstream end 48. It becomes possible to reduce the flow resistance of the cooling water in the cooling water passage 20. Further, since the upper portion of the downstream end portion 48 is covered by an inclined wall 49 that connects the lower end portion of the plug cylinder portion 33 and the upper end portion of the left side wall 38, the cylinder head is formed along with the formation of the downstream end portion 48. It is possible to strengthen the structure of the cylinder head 11 by connecting the upper portion and the lower portion of the cylinder 11.

  In the present embodiment, the configuration of the outlet 51 according to the present invention is applied to the left side wall 38 of the cylinder head 11. However, in another different embodiment, the configuration of the outlet 51 according to the present invention is applied to the right side wall 36 and both the front and rear side walls. May be applied. In the water embodiment, the configuration of the cylinder head 11 according to the present invention is adopted in the parallel four-cylinder engine. However, in other different embodiments, the present invention is applied to other types of engines such as a single-cylinder engine and a V-type engine. Such a configuration of the cylinder head 11 may be applied.

  In the present embodiment, the configuration of the cylinder head 11 according to the present invention is applied to the engine 5 of the on-road type motorcycle 1. However, in another different embodiment, the present invention is applied to the motorcycle 1 such as an off-road type or a scooter. The configuration of the cylinder head 11 according to the above may be applied. Further, the configuration of the cylinder head 11 according to the present invention can be applied to the engine 5 such as an ATV (roughly traveling vehicle), an automobile (four-wheeled vehicle), a snow vehicle, and an outboard motor.

DESCRIPTION OF SYMBOLS 10 Cylinder 11 Cylinder head 12 Cylinder head cover 20 Cooling water path 26 Deck surface 33 Plug cylinder part 34 Plug hole 35 Cam journal receiving part 38 Left side wall (one side wall)
40, 41 Camshaft 42 Joint flange 48 Downstream end portion 50 Flange portion 51 Outlet 54 Outlet pipe 56 Offset portion 58 Outermost edge portion

Claims (6)

A deck surface joined to the cylinder is provided at the lower end, a cooling water passage for allowing cooling water to pass therethrough is provided, and a structure of a cylinder head for a water-cooled internal combustion engine used in a motorcycle,
An outlet of the cooling water passage is provided on one side wall side, the outlet is formed horizontally along the one side wall, and is provided obliquely upward with respect to the deck surface;
At the upper end of the cylinder head, cam journal receiving portions for supporting the cam journal of the camshaft are provided on the front exhaust side and the rear intake side, respectively .
A flange portion capable of joining an outlet hose is provided around the outlet, and the flange portion is formed so as to overlap only with the cam journal receiving portion on the front exhaust side in the axial direction view of the camshaft,
The flange portion is provided at an upper end portion of the one side wall, and a main frame of the motorcycle is disposed in a space formed below the flange portion. Construction. A concave portion for processing the cam journal receiving portion is provided on the same axis as the cam journal receiving portion at the upper edge portion of the side wall opposite to the one side wall of the cylinder head.
2. The water-cooled internal combustion engine according to claim 1, wherein the cam journal receiving portion is processed only from one side, and the concave portion is not formed in an upper edge portion of the one side wall of the cylinder head. Engine cylinder head structure.   2. A joining flange is provided on the outer periphery of the upper end of the cylinder head, and the joining flange and at least a part of the flange portion are provided at the same height from the deck surface. 3. The structure of the cylinder head for a water-cooled internal combustion engine according to 2.   The one side wall is provided with an offset portion toward the inside, and the flange portion is formed at the offset portion, so that at least a part of the flange portion is disposed on the inner side of the outermost edge portion of the one side wall. The structure of a cylinder head for a water-cooled internal combustion engine according to any one of claims 1 to 3.   The structure of the cylinder head for a water-cooled internal combustion engine according to any one of claims 1 to 4, wherein the outlet hose is provided above a cylinder head cover that covers an upper surface of the cylinder head.   The cylinder head is provided with a plug cylinder portion in which a plug hole is formed perpendicular to the deck surface, and a downstream end portion of the cooling water passage extends obliquely upward from the root side of the plug hole. 6. The structure of a cylinder head for a water-cooled internal combustion engine according to any one of claims 1 to 5, wherein the structure is formed in a straight line, and the outlet is connected to the downstream end.