JP4795905B2 - Water-cooled engine - Google Patents

Description

  The present invention relates to a water-cooled engine in which cooling water flows around a cylindrical wall in which a spark plug is inserted.

  A conventional water-cooled engine of this type is disclosed in Patent Document 1, for example. The water-cooled engine disclosed in Patent Document 1 is a multi-cylinder engine having two intake valves and two exhaust valves per cylinder. The intake and exhaust ports that open and close these intake / exhaust valves are formed on one side and the other side of the cylinder head as viewed from the axial direction of the crankshaft. In addition, this water-cooled engine is equipped with a spark plug near the center of the combustion chamber when viewed from the axial direction of the cylinder. The spark plug is inserted into a cylindrical wall extending in the axial direction of the cylinder through a coolant passage formed in the cylinder head, and is screwed to the ceiling wall of the combustion chamber.

  The cooling water passage is defined by a space surrounded by a bottom wall including a ceiling wall of the combustion chamber, an upper wall located on the opposite side of the combustion chamber across the bottom wall, and both side walls and front and rear walls. Is formed. The bottom wall and the top wall are formed so as to extend from a front end portion of the cylinder head located on one end side in the axial direction of the crankshaft to a rear end portion located on the other end side in the axial direction.

One side wall of the both side walls includes a wall that forms an intake port, and extends from the bottom wall to the top wall at one side of the cylinder head when viewed from the axial direction of the crankshaft.
The other side wall includes a wall that forms an exhaust port, and extends from the bottom wall to the upper wall at the other side of the cylinder head when viewed from the axial direction of the crankshaft.

  The front wall extends in a direction intersecting the axial direction of the crankshaft at the front end of the cylinder head so as to connect the front ends of the side walls. The rear wall extends in a direction intersecting the axial direction of the crankshaft at the rear end of the cylinder head so as to connect the rear ends of the both side walls.

The cooling water passage is formed so that the cooling water flows in the axial direction of the crankshaft (the front-rear direction of the cylinder head). The cylindrical wall into which the spark plug is inserted is formed to extend from the ceiling wall to the upper wall of the cooling water passage.
In this type of conventional engine, the portion of the ceiling wall near the spark plug is the hottest, so this portion, that is, the connecting portion between the ceiling wall and the cylindrical wall (the base of the cylindrical wall) is cooled with water. It is important to cool by.
Japanese Patent Laid-Open No. 7-229446

  However, the conventional water-cooled engine described above has a problem that the base of the cylindrical wall cannot be efficiently cooled. This is considered to be because the amount of cooling water that passes between the cylindrical wall and both side walls of the cooling water passage is larger than the amount of cooling water that hits the cylindrical wall and cools it.

  The present invention has been made to solve such a problem, and provides a water-cooled engine capable of increasing the amount of cooling water hitting a cylindrical wall into which a spark plug is inserted and cooling the cylindrical wall efficiently. With the goal.

In order to achieve this object, a water-cooled engine according to the present invention includes a ceiling wall of a combustion chamber that constitutes a bottom wall of a cooling water passage in a cylinder head, and an opposite side of the combustion chamber across the ceiling wall. A cooling water passage upper wall, a spark plug insertion cylindrical wall formed so as to extend from the ceiling wall to the cooling water passage upper wall, and the cylindrical wall as viewed from the upstream side of the cooling water passage. In a water-cooled engine having a pair of cooling water passage side walls extending from the bottom wall to the upper wall of the cooling water passage on both sides, one of the pair of cooling water passage side walls is an intake port or an exhaust. The wall forming the port includes a pair of convex portions for supporting the pair of valve shafts, and is formed by these convex portions and the cooling water passage upper wall. Cooling water to the cylindrical wall at the corner The protrusion for guiding provided, said pair of projections is disposed on the upstream side and the downstream side of the cooling water passage to said cylindrical wall, hit the projections located on the upstream side of the cooling water passage of the projections The cooling water is guided to the upstream half of the cooling water passage in the cylindrical wall, and the cooling water hitting the protrusion located on the downstream side of the cooling water passage is downstream of the cooling water passage in the cylindrical wall. The line connecting the tip end portions of the protrusions does not intersect the cylindrical wall.

Water-cooled engine according to the invention described in claim 2 is the water-cooled engine according to claim 1, wherein the projections are those formed in the protrusion in the wall forming the intake port .

According to the present invention, among the cooling water flowing in the cooling water passage, the cooling water hitting the protrusion provided on the side wall of the cooling water passage is changed in the direction of flow by the protrusion and flows toward the cylindrical wall. Become.
For this reason, according to this invention, since the quantity of the cooling water which hits a cylindrical wall can be increased, the water-cooled engine which can cool a cylindrical wall efficiently can be provided. As a result, the water-cooled engine according to the present invention reduces the temperature in the vicinity of the spark plug mounting portion that is the highest temperature, and therefore, knocking is less likely to occur.

  According to the second aspect of the present invention, since the protrusion is provided on the intake port forming wall at a position close to the cylindrical wall, the protrusion can be provided close to the cylindrical wall. The cooling water whose direction of flow is changed by the protrusion can be reliably applied to the cylindrical wall.

In addition, since the cooling water hitting the protrusion changes in the direction toward the exhaust port, the amount of cooling water flowing in the vicinity of the wall forming the exhaust port can be increased.
Therefore, according to this invention, while being able to cool the said cylindrical wall much more efficiently, cooling of the wall which forms an exhaust port can be accelerated | stimulated.

Hereinafter, an embodiment of a water-cooled engine according to the present invention will be described in detail with reference to FIGS.
1 is a front view of a water-cooled engine according to the present invention, FIG. 2 is a bottom view of the cylinder head, FIG. 3 is a rear view of the cylinder head, and FIG. 4 is a cross-sectional view showing a part of the cylinder head and cylinder block. The broken position in FIG. 4 is indicated by the IV-IV line in FIG.
FIG. 5 is a cross-sectional view taken along the line V-V of FIG. 4, and FIGS. 6 and 7 are cross-sectional views showing part of the cylinder head and cylinder block. 6 is indicated by the VI-VI line in FIG. 2, and the fracture position in FIG. 7 is indicated by the VII-VII line in FIG.

  8 is a sectional view taken along line VIII-VIII of the cylinder head in FIG. 7, FIG. 9 is a sectional view taken along line IX-IX in FIG. 7, and FIG. 10 is a sectional view taken along line XX in FIG. In FIG. 10, the fracture position in FIG. 6 is indicated by the VI-VI line, and the fracture position in FIG. 7 is indicated by the VII-VII line. 11 is a bottom view of the head gasket, FIG. 12 is a block diagram showing the configuration of the cooling system, and FIG. 13 is a perspective view for explaining the configuration of the sub-cooling water passage.

  In these drawings, the reference numeral 1 indicates a water-cooled engine according to this embodiment. This engine 1 is a water-cooled four-cycle V-type six-cylinder engine mounted on an automobile, and includes a first cylinder row 2 located on the left side in FIG. 1 and a second cylinder row 3 located on the right side in FIG. I have. In this specification, as shown in FIG. 1, when the engine 1 is viewed from the axial direction of the crankshaft 4, the two cylinder rows 2 and 3 are close to the other cylinder row on both sides in the left-right direction. One side is called the inside of the V bank, and the other side is called the outside of the V bank.

Further, in this specification, as shown in FIG. 1, one end where the transmission means 7 for connecting the intake / exhaust camshafts 5 and 6 to the crankshaft 4 is referred to as a front end and the opposite side (in FIG. The back side of the paper is called the rear edge. Although not shown, a front cover for covering the transmission means 7 is attached to the front end of the water-cooled engine 1.
Since the two cylinder rows 2 and 3 described above have the same configuration, the first cylinder row 2 will be described in detail below, and the description of each member of the second cylinder row 3 is the same. Reference numerals are omitted.

As shown in FIG. 1, the first cylinder row 2 and the second cylinder row 3 include a cylinder portion 8a protruding from the cylinder block 8 for each of the cylinder rows 2 and 3, and an upper portion of the cylinder portion 8a. The cylinder head 9 is mounted, and a cam housing 9a and a head cover 10 provided on the cylinder head 9 are configured.
Cylinder holes 11 for three cylinders are formed in each cylinder portion 8 a of the cylinder block 8 so as to be aligned in the axial direction of the crankshaft 4. In FIG. 1, 12 indicates a piston fitted in the cylinder hole 11, and S indicates a combustion chamber.

  As shown in FIG. 7, the cylinder head 9 has an intake port 21 and an exhaust port 22, which will be described later, and a cooling water passage 23. The cylinder head 9 is placed on the cylinder block 8 via a head gasket 24, It is attached by a head bolt (not shown). A bolt hole for inserting the head bolt is denoted by reference numeral 25 in FIGS. The intake port 21 is provided inside the V bank of the cylinder head 9, and the exhaust port 22 is provided outside the V bank of the cylinder head 9.

The intake port 21 has a bifurcated shape having a pair of branch ports 21a and 21a (see FIG. 8) at the downstream end, and is formed as a so-called siamese port. Is opened and closed by. These intake valves 26, 26 are driven by a valve operating device 27 provided in the cylinder head 9, as shown in FIG. This valve operating device 27 has a structure for transmitting a driving force from the intake camshaft 5 to the intake valve 26 via the rocker arm 28.
In the vicinity of the upstream end portion of the intake port 21 in the cylinder head 9, an injector 29 that injects fuel into the pair of branch ports 21a and 21a is attached.

  The exhaust port 22 is configured to collect exhaust gas from each cylinder and guide it to an exhaust pipe (not shown). More specifically, as shown in FIGS. 9 and 10, the exhaust port 22 includes first to third upstream portions 31 to 33 provided for each cylinder, and a merging portion that connects these upstream portions 31 to 33. 34. The exhaust port 22 is molded by casting together with the intake port 21 of the cylinder head 9, the ceiling wall 35 of the combustion chamber S (see FIG. 7), and the like. The walls forming the first to third upstream portions 31 to 33 of the exhaust port 22 are indicated by 36 to 38 in FIG. 13, and the walls forming the merge portion 34 are indicated by 39.

  Among the first to third upstream portions 31 to 33, the first upstream portion 31 is, as shown in FIG. 9, a front end portion 9A of the cylinder head 9 (one end portion corresponding to the front end portion of the water-cooled engine 1). ), The third upstream portion 33 is located at the rear end portion of the cylinder head 9, and the second upstream portion 32 is located between the first upstream portion 31 and the third upstream portion 33. is doing.

  As shown in FIG. 7, these first to third upstream portions 31 to 33 are formed to extend from the combustion chamber S to the upper side outside the V bank of the cylinder head 9. Further, as shown in FIG. 9, these upstream portions have a bifurcated shape having a pair of branch ports 31a, 31a, 32a, 32a, 33a, 33a at the upstream end portion, and are formed as so-called siamese ports. ing. These branch ports are opened and closed by exhaust valves 41, respectively. These exhaust valves 41 are driven by the valve gear 27 having an exhaust camshaft 6 and a rocker arm 42 as shown in FIG.

  As shown in FIGS. 9, 10, and 13, the merging portion 34 is formed so that the upstream end is located at the front end portion 9 </ b> A of the cylinder head 9 and extends from the upstream end to the rear end portion 9 </ b> B of the cylinder head 9. ing. The upstream end of the merging portion 34 is connected so that no step is formed at the downstream end of the first upstream portion 31. On the other hand, the downstream end of the merging portion 34 is formed in a shape that extends the downstream end of the third upstream portion 33 to the outside of the V bank.

  As shown in FIG. 10, the downstream end of the merging portion 34 opens in a side surface 43 outside the V bank of the cylinder head 9. The side surface 43 constitutes a mounting seat for mounting an exhaust pipe (not shown). A supercharger is provided at an intermediate portion of the exhaust pipe. As shown in FIGS. 7, 9, and 10, a recessed portion 45 that is released toward the side is formed in the side portion 44 outside the V bank of the cylinder head 9 in which the side surface 43 is formed. A part of the wall 39 forming the merge part 34 of the exhaust port 22 constitutes a part of the bottom of the recessed part 45 and is exposed to the outside of the engine 1.

The ceiling wall 35 formed integrally with the intake port 21 and the exhaust port 22 described above is formed with a recess 46 so that the lower surface is recessed upward as shown in FIGS. Yes. The downstream end of the intake port 21 and the upstream end of the exhaust port 22 are open to the recess 46.
Further, as shown in FIG. 6, a spark plug 47 is attached to a portion of the ceiling wall 35 that intersects the cylinder axis C when viewed from the axial direction of the crankshaft 4. The spark plug 47 is provided at a substantially central portion of the combustion chamber S when viewed from the axial direction of the cylinder.

  The spark plug 47 is inserted into a cylindrical wall 51 (see FIGS. 8 to 10) provided in a cooling water passage 23 (described later) of the cylinder head 9, and as shown in FIG. It is screwed into the plug hole 52 drilled in. As shown in FIG. 6, the cylindrical wall 51 is formed so as to extend upward from the ceiling wall 35 in a cooling water passage 23 described later.

  The upper end portion of the cylindrical wall 51 is connected to the upper wall 53 of the cooling water passage 23. As shown in FIG. 6, the spark plug 47 and the cylindrical wall 51 according to this embodiment are inclined so as to be gradually located on the outer side of the V bank as they go upward as viewed from the axial direction of the crankshaft 4.

  As shown in FIGS. 8 and 12, the cooling water passage 23 formed in the cylinder head 9 is formed so as to extend from the front end portion 9 </ b> A of the cylinder head 9 toward the rear end portion 9 </ b> B. As shown in FIG. 2, the cooling water passage 23 surrounds the main inlet 54 formed at the front end 9A (the upper end in FIG. 2) of the cylinder head 9 and the combustion chamber S (recess 46) for each cylinder. The sub-inlet 55 provided at such a position, the through-hole 56 provided at a position corresponding to the spark plug 47, and the head gasket 24 at a position facing the main, sub-inlet 54, 55 and through-hole 56. It is connected to the cooling water passage 60 (see FIGS. 6, 7 and 12) in the cylinder block 8 through the holes 57 to 59 (see FIG. 11).

  The amount of cooling water flowing into the main inlet 54, the sub inlet 55, and the through hole 56 is determined by the size of the opening areas of the holes 57 to 59 formed in the head gasket 24. In this embodiment, the opening areas of these holes 57 to 59 are set so that the cooling water flows most into the main inlet 54.

  As shown in FIG. 2, among the holes opened in the lower surface of the cylinder head 9, a hole 61 provided at a position surrounding the combustion chamber S (recess 46) is formed by the head gasket 24, as with the sub-inlet 55. Since it is blocked, cooling water does not pass. The hole 61 is formed by a leg portion of a core (not shown) for forming a cooling water passage, for example. Further, as shown in FIG. 4, a plug member 63 is press-fitted into the hole 62 formed between the recesses 46 on the lower surface of the cylinder head 9, and is closed by the plug member 63. The head gasket 24 is provided with a hole 64 for passing a head bolt, a hole 65 for passing oil, and the like in addition to the holes 57 to 59 for allowing the cooling water to pass therethrough.

  The cooling water passage 60 in the cylinder block 8 is connected to a discharge port of the cooling water pump 72 by a cooling water supply passage 71 as shown in FIG. The suction port of the cooling water pump 72 is connected to the cooling water outlet 74a of the radiator 74 or the downstream end of the radiator bypass passage 75 via a thermostat 73 that is well known in the art. A cooling water inlet 74 b of the radiator 74 is connected to a cooling water outlet 78 of the cylinder head 9 by a cooling water return passage 76. An upstream end portion of the radiator bypass passage 75 is connected to an intermediate portion of the cooling water return passage 76.

  As shown in FIGS. 3 and 10, the coolant outlet 78 of the cylinder head 9 is formed at the rear end portion 9 </ b> B of the cylinder head 9 and inside the V bank (on the left side in FIG. 3). There is an opening on the rear surface. As shown in FIG. 1, the cylinder head 9 is attached to the cylinder block 8 in an inclined state so that the inside of the V bank is relatively high. That is, the cooling water outlet 78 is located at a relatively high position in the cooling water passage 23 in a state where the cylinder head 9 is attached to the cylinder block 8.

  For this reason, the air mixed in the cooling water passage 23 of the cylinder head 9 is discharged from the cooling water outlet 78 without remaining in the cooling water passage 23. As described above, the cooling water outlet 78 is formed at the rear end portion 9B of the cylinder head 9 and the main inlet 54 is formed at the front end portion 9A of the cylinder head 9, so that the inside of the cooling water passage 23 of the cylinder head 9 is formed. This cooling water flows from the front end 9A side to the rear end 9B side of the cylinder head 9 as shown by arrows in FIGS.

  As shown in FIG. 8, the cooling water passage 23 in the cylinder head 9 includes a main cooling water passage 81 extending from the front end portion 9A to the rear end portion 9B of the cylinder head 9 along the ceiling wall 35 of the combustion chamber, and the cylinder head. 9 and a sub cooling water passage 82 extending from the front end portion 9A to the rear end portion 9B through the V bank outside. Both end portions (upstream end portion and downstream end portion) of the sub cooling water passage 82 are connected to both end portions of the main cooling water passage 81. The main and sub-inlets 54 and 55 and a through-hole 56 described later are located in the main cooling water passage 81.

  As shown in FIGS. 4, 6, 7 and FIGS. 8 to 10, the main cooling water passage 81 includes a bottom wall 83 (a wall attached to the cylinder block 8) of the cylinder head 9 including the ceiling wall 35 of the combustion chamber S. The upper wall 53 located on the opposite side of the combustion chamber S across the bottom wall 83, the inner wall 84 located on the inner side of the V bank of the cylinder head 9, and the front end 9A of the cylinder head 9 It is formed by a space surrounded by the wall 85 and the rear wall 86 located at the rear end 9 </ b> B of the cylinder head 9.

  As shown in FIG. 8, a partition wall 87 for partitioning the main cooling water passage 81 and the sub cooling water passage 82 in the vicinity of the bottom wall 83 is integrally formed on the bottom wall 83 so as to protrude upward. ing. As shown in FIG. 6, the partition wall 87 is formed at a portion sandwiched between the second upstream portion 32 of the exhaust port 22 and the bottom wall 83. Further, as shown in FIG. 13, the partition wall 87 is bridged between the two cylindrical walls 88 and 88 for inserting the head bolts, which are provided upright in the main cooling water passage 81. FIG. 13 shows the configuration of the cooling water passage formed around the exhaust port 22, and members such as the cylindrical wall 51 for plug insertion and the plug member 63 are omitted. In addition to the bolt holes 25, oil holes for allowing oil to flow downward from the valve cam chamber 89 (see FIG. 1) located above the cylinder head 9 are formed in the head bolt insertion cylindrical walls 88, 88. 90 is drilled.

  As shown in FIGS. 6, 9, 10 and 13, the upper wall 53 has a plate 91 for guiding the cooling water flowing in the main cooling water passage 81 toward the sub cooling water passage 82, and the main cooling water passage. The protrusions 92 for partitioning 81 and the sub-cooling water passage 82 in the vicinity of the upper wall 53 are integrally formed so as to protrude downward. As shown in FIG. 10, among the three cylinders provided in each of the cylinder rows 2 and 3 of the water-cooled engine 1, the plate 91 is provided between the front end cylinder and the central cylinder. These are provided at two locations corresponding to between the center cylinder and the rear end cylinder. As shown in FIG. 10, the protrusion 92 is formed to extend from the front wall 85 to the vicinity of the rear wall 86.

  As shown in FIG. 7, the inner wall 84 is formed so as to include a wall 93 that forms the intake port 21. On the wall 93 forming the intake port 21, a convex portion 93a for supporting the valve shaft of the intake valve 26 is formed. As shown in FIG. 5, the convex portion 93a has a through-hole 93b through which the valve stem guide 26a (see FIG. 7) is inserted.

As shown in FIGS. 7, 9, and 10, at the corner portion formed by the convex portion 93 a and the upper wall 53, the cooling water flowing in the main cooling water passage 81 is passed through the cylindrical wall 51 for inserting the spark plug. Protrusions 94 are provided for guiding to As shown in FIGS. 9 and 10, the projections 94 are provided in the same manner on all the convex portions 93 a provided on the cylinder head 9 at six locations. As shown in FIG. 5, the protrusion 94 is formed so as to protrude toward the cylindrical wall 51 at the distal end portion of the convex portion 93 a adjacent to the cylindrical wall 51.

  The projection 94 is formed to have a plate shape extending in a direction intersecting the axial direction of the crankshaft. The thickness of the plate-like protrusion 94 is formed so as to gradually decrease from the base end portion toward the tip end portion. Further, as shown in FIGS. 4 and 7, the protrusion 94 is formed at a corner portion formed by the tip edge of the convex portion 93 a and the lower edge of the upper wall 53 as viewed from the front end side of the cylinder head 9. It is formed in a triangular shape so as to regulate the flow of the cooling water here.

  Thus, by providing the projection 94 at the corner portion, it is possible to prevent the cooling water from passing straight through the corner portion, and as shown by an arrow in FIG. Water can be guided to the cylindrical wall 51. Of the two protrusions 94 provided for each cylinder, the cooling water that hits the protrusion 94 located on the front side of the cylinder head 9 (upstream side of the cooling water passage 23) causes the cylinder 94 in the cylindrical wall 51. It is led to the front half 51a to cool it.

  The cooling water hitting the projection 94 located on the rear side of the two projections is guided by this projection 94 to the rear half 51b of the cylinder head 51 in the cylindrical wall 51 to cool it. Of the cooling water that hits the projection 94 located on the rear side, the remaining cooling water that did not hit the cylindrical wall 51 flows to the sub-cooling water passage 82 side (exhaust port 22 side) described later.

  The through hole 56 provided in the bottom wall 83 is for directly applying the cooling water in the cooling water passage 60 of the cylinder block 8 to the base portion 51c (see FIG. 6) of the spark plug cylindrical wall 51. The bottom wall 83 is formed obliquely so as to face the base 51c.

  As shown in FIGS. 6 to 8 and FIG. 13, the auxiliary cooling water passage 82 is formed so that cooling water flows around the exhaust port 22. More specifically, the auxiliary cooling water passage 82 includes a lower wall 101 protruding outward from the V bank from the bottom wall 83 and an upper wall extending portion extending outward from the main cooling water passage 81 in the upper wall 53 from the V bank. 102, an outer wall 103 located outside the V bank of the cylinder head 9, a front wall extending portion 104 extending outside the V bank from the main cooling water passage 81 in the front wall 85, and a main wall in the rear wall 86. It is formed by a space surrounded by a rear wall extending portion 105 extending from the cooling water passage 81 to the outside of the V bank.

  The outer wall 103 forms the bottom of the recessed portion 45 formed outside the V bank of the cylinder head 9. That is, the wall 39 that forms the merging portion 34 of the exhaust port 22 constitutes a part of the outer wall 103. Further, as shown in FIGS. 4, 6, 7 and 13, the auxiliary cooling water passage 82 is divided into a lower passage 107 and an upper passage 108 by the exhaust port 22 and a partition wall 106 extending in parallel with the lower wall 101. It has been.

  As shown in FIG. 8, the lower passage 107 includes a first communication port 111 formed between the front wall extending portion 104 and the first upstream portion 31, and the first upstream portion 31 and the partition wall. 87 (a second communication port 112 formed between the cylindrical wall 88 for inserting the head bolt) and a third communication port formed between the partition wall 87 and the third upstream portion 33. 113 and a fourth communication port 114 formed between the third upstream portion 33 and the rear wall extending portion 105 are communicated with the main cooling water passage 81.

  As shown in FIG. 13, the upper passage 108 communicates with the main cooling water passage 81 between the protrusion 92 provided on the upper wall 53 and a member positioned below the protrusion 92. The members positioned below the protrusion 92 are the walls 36 to 38 and the bottom wall 83 that form the first to third upstream portions 31 to 33 of the exhaust port 22.

  In the water-cooled engine 1 configured as described above, when the cooling water pump 72 is operated, the cooling water passes from the cooling water passage 60 of the cylinder block 8 through the main inlet 54, the sub-inlet 55, the through hole 56, and the like. 9 flows into the main cooling water passage 81. A part of the cooling water flowing into the main cooling water passage 81 flows into the sub cooling water passage 82, and the other cooling water flows in the main cooling water passage 81 in the axial direction of the crankshaft 4.

The cooling water that has flowed into the sub-cooling water passage 82 cools the walls 36 to 38 that form the first to third upstream portions 31 to 33 of the exhaust port 22 and the wall 39 that forms the joining portion 34.
The cooling water flowing in the main cooling water passage 81 cools the ceiling wall 35 of the combustion chamber S, the spark plug insertion cylindrical wall 51, the upstream ends of the walls 36 to 38 extending from the ceiling wall 35, and the like. .

  Among the cooling water flowing in the main cooling water passage 81, a part of the cooling water flowing toward the rear end portion 9 </ b> B side of the cylinder head 9 along the inner wall 84 is a convex portion provided on the intake port forming wall 93. When it exceeds 93a, it hits the projection 94. The cooling water hitting the projection 94 in this way is changed in the direction of flow by the projection 94 and flows toward the cylindrical wall 51.

  For this reason, according to the water-cooled engine 1 by this embodiment, the quantity of the cooling water which hits the cylindrical wall 51 can be increased, and the cylindrical wall 51 can be cooled efficiently. As a result, in the water-cooled engine 1 according to this embodiment, knocking is unlikely to occur because the temperature in the vicinity of the spark plug mounting portion that is the highest temperature decreases.

  Further, the projection 94 according to this embodiment is provided on a wall 93 for forming an intake port at a position close to the cylindrical wall 51. For this reason, according to the water-cooled engine 1 according to this embodiment, since the projection 94 can be provided close to the cylindrical wall 51, the cooling water whose direction of flow is changed by the projection 94 is reliably supplied to the cylindrical wall. 51.

  Further, since the direction of the cooling water that has hit the projection 94 changes in the direction toward the exhaust port 22, the amount of the cooling water flowing in the vicinity of the walls 36 to 39 forming the exhaust port 22 can be increased. it can. Therefore, according to the water-cooled engine 1, the cylindrical wall 51 can be cooled more efficiently, and cooling of the walls 36 to 39 forming the exhaust port 22 can be promoted.

  The water-cooled engine 1 according to the above-described embodiment is formed such that the spark plug 47 and the cylindrical wall 51 are inclined toward the exhaust port side. For this reason, in this embodiment, a configuration is adopted in which the projection 94 restricts the passage of the cooling water through the cooling water passage that opens widely between the cylindrical wall 51 and the inner wall 84. However, when the spark plug 47 and the cylindrical wall 51 are inclined in the opposite direction, the space between the walls 36 to 38 forming the exhaust port 22 and the cylindrical wall 51 is relatively wide. The projections 94 are provided on the walls 36 to 38. The protrusions 94 can also be provided on both the inner wall 84 having the wall 93 that forms the intake port 21 and the walls 36 to 38 that form the exhaust port 22.

  The cylinder head 9 of the water-cooled engine 1 according to this embodiment is formed with an exhaust port 22 having a structure for joining the exhaust gases of the cylinders. However, the present invention is not limited to such a limitation, and can be applied to a general water-cooled engine in which the exhaust port 22 is formed so as to be independent for each cylinder. The present invention can also be applied to an engine different from the V-type engine, for example, an in-line multi-cylinder engine for automobiles and a single-cylinder engine for motorcycles.

1 is a front view of a water-cooled engine according to the present invention. It is a bottom view of a cylinder head. It is a rear view of a cylinder head. It is sectional drawing which shows a cylinder head and a part of cylinder block. It is the VV sectional view taken on the line in FIG. It is sectional drawing which shows a cylinder head and a part of cylinder block. It is sectional drawing which shows a cylinder head and a part of cylinder block. It is the VIII-VIII sectional view taken on the line of the cylinder head in FIG. It is the IX-IX sectional view taken on the line of the cylinder head in FIG. FIG. 8 is a cross-sectional view of the cylinder head in FIG. 7 taken along line XX. It is a bottom view of a head gasket. It is a block diagram which shows the structure of a cooling system. It is a perspective view for demonstrating the structure of a subcooling water channel | path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Water-cooled engine, 4 ... Crankshaft, 8 ... Cylinder block, 9 ... Cylinder head, 11 ... Cylinder hole, 21 ... Intake port, 22 ... Exhaust port, 23, 60 ... Coolant passage, 35 ... Ceiling wall, 47 DESCRIPTION OF SYMBOLS ... Spark plug, 51 ... Cylindrical wall, 74 ... Radiator, 81 ... Main cooling water passage, 84 ... Inner side wall, 93 ... Wall, 93a ... Projection, 94 ... Protrusion, S ... Combustion chamber.

Claims (2)

A ceiling wall of the combustion chamber constituting the bottom wall of the cooling water passage in the cylinder head;
A cooling water passage upper wall located on the opposite side of the combustion chamber across this ceiling wall;
A cylindrical wall for inserting a spark plug formed so as to extend from the ceiling wall to the cooling water passage upper wall;
In a water-cooled engine comprising a pair of cooling water passage side walls extending from the bottom wall to the cooling water passage upper wall on both sides of the cylindrical wall as seen from the upstream side of the cooling water passage,
One of the pair of cooling water passage side walls includes a wall that forms an intake port or an exhaust port,
The wall forming the port further includes a pair of convex portions for supporting the pair of valve shafts,
Providing a projection that guides cooling water to the cylindrical wall at the corner formed by these convex portions and the cooling water passage upper wall,
The pair of protrusions are disposed on the upstream side and the downstream side of the cooling water passage with respect to the cylindrical wall,
Of these protrusions, the cooling water that hits the protrusion located on the upstream side of the cooling water passage is guided to the upstream half of the cooling water passage in the cylindrical wall, and the protrusion located on the downstream side of the cooling water passage. The cooling water that hits is guided to the downstream half of the cooling water passage in the cylindrical wall,
A water-cooled engine characterized in that a line connecting tip portions of the protrusions does not intersect the cylindrical wall.   2. The water-cooled engine according to claim 1, wherein the protrusion is formed on a convex portion provided on a wall forming the intake port.

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