JP4372374B2 - engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, the cylinder head fastened to the cylinder block is integrally provided with a protruding portion that protrudes outward from the cylinder block, and an ignition plug having an axis arranged in a plane perpendicular to the axis of the camshaft is attached. In particular, the present invention relates to an improvement in a structure for draining water from a spark plug chamber formed in a cylinder head so that a part of the spark plug faces.
[0002]
[Prior art]
Conventionally, such an engine is already known, for example, in JP-A-7-259541.
[0003]
[Problems to be solved by the invention]
In the conventional engine, the spark plug chamber that faces a part of the spark plug extending in the cylinder axial direction is formed in the cylinder head extending in the axial direction of the spark plug, and one end is opened at the lower portion of the spark plug chamber. The drain hole is provided in the cylinder head so as to open to the outer surface of the cylinder head on the outer side of the cylinder block, and the length of the drain hole becomes relatively long.
[0004]
On the other hand, there is a desire to reduce the weight of the cylinder head, and it is desirable to simplify the water draining structure from the spark plug chamber while meeting such a demand.
[0005]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an engine that simplifies the water draining structure from the spark plug chamber while reducing the weight of the cylinder head.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the cylinder head fastened to the cylinder block is integrally provided with a protruding portion that protrudes outward from the cylinder block and is orthogonal to the axis of the camshaft. to the engine spark plug arranged axis is mounted in a plane, the spark plug chamber for exposing a portion of the spark plug is formed in the cylinder head so as to place the part on the projecting portion Rutotomoni, A fastening boss for fastening the intake device or the exhaust device to the projecting portion is provided in the cylinder head so as to enter the lower part of the spark plug chamber, and the spark plug and the fastening in a direction along the axis of the camshaft. drain hole which opens one end to a lower portion of the spark plug chamber between the boss is provided on the projecting portion, the other end of the water drain hole Characterized in that it opens to the lower outer surface of the projecting portion.
[0007]
In order to achieve the above object, according to a second aspect of the present invention, the cylinder head fastened to the cylinder block is integrally provided with a protruding portion that protrudes outward from the cylinder block, and the camshaft has an axial line. In an engine to which a spark plug having an axis line arranged in an orthogonal plane is mounted, a spark plug chamber that faces a part of the spark plug is formed in the cylinder head so that a part is disposed in the projecting portion. A fastening boss for fastening the intake device or the exhaust device to the projecting portion is provided in the cylinder head so as to enter the lower part of the spark plug chamber, and the fastening boss is arranged in a direction along the axis of the camshaft. One end of a drain hole provided in the projecting portion is opened at the lower portion of the spark plug chamber at a position between the spark plug and the spark plug. The other end of the vent hole is open to the lower outer surface of the protrusion, and a guide wall for guiding water that has entered the periphery of the spark plug to the drain hole side is provided between the inner wall of the spark plug chamber and the fastening boss. It is provided.
[0008]
In order to achieve the above object, according to a third aspect of the present invention, a cylinder head fastened to the cylinder block is integrally provided with a protruding portion that protrudes outward from the cylinder block, and the axis of the cam shaft is provided. In an engine to which a spark plug having an axis line arranged in an orthogonal plane is mounted, a spark plug chamber that faces a part of the spark plug is formed in the cylinder head so that a part is disposed in the projecting portion. The projecting portion is provided with a drain hole having one end opened in the lower portion of the spark plug chamber and the other end opened in the lower outer surface of the projecting portion, and the spark plug chamber is provided on the projecting end side of the projecting portion. At least a lower portion of the inner surface of the inner surface of the camshaft is formed in a flat surface parallel to the camshaft, and a screw hole for screwing a fastening bolt for fastening the intake device or the exhaust device is formed in the protrusion. Wherein the projecting end face of the part and is provided over between the flat surface.
[0009]
According to each structure of Claims 1-3, since the ignition plug chamber which arrange | positions one part in a protrusion part is provided in a cylinder head, the volume of an ignition plug chamber is set comparatively large and the weight reduction of a cylinder head is aimed at. The cylinder head is provided with a drain hole that opens at one end to the lower portion of the spark plug chamber and opens the other end to the lower outer surface of the projection, that is, the lower outer surface of the cylinder head outside the cylinder block. Therefore, the water that has entered the spark plug chamber can be surely discharged by the water drain hole that is shortened and simplified.
[0010]
In particular , according to the above-described configuration of the first aspect, when the fastening boss for fastening the intake device or the exhaust device is shifted from the spark plug chamber, an increase in the size of the cylinder head is unavoidable. By making it enter the lower part, it is possible to avoid an increase in the size of the cylinder head and to guide the water that has entered the spark plug chamber from around the spark plug to the drain hole side so that the fastening boss does not get in the way. .
[0011]
In particular , according to the above configuration of claim 2, when the fastening boss for fastening the intake device or the exhaust device is shifted from the spark plug chamber, the cylinder head is inevitably enlarged. By making it enter the lower part, it is possible to avoid an increase in the size of the cylinder head, and the water that has entered the spark plug chamber from around the spark plug is guided to the drain hole side by the guide wall so that the fastening boss does not get in the way. And the rigidity of the fastening boss can be increased by the guide wall.
[0012]
In particular , according to the above configuration of claim 3, when the fastening boss for fastening the intake device or the exhaust device is shifted from the spark plug chamber, it is inevitable that the cylinder head is enlarged. By arranging the cylinder heads correspondingly, it is possible to avoid an increase in the size of the cylinder head, and the water that has entered the spark plug chamber from around the spark plug is guided to the drain hole side on a flat surface so that the fastening portion does not get in the way. be able to.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.
[0014]
1 to 13 show an embodiment of the present invention. FIG. 1 is an upper longitudinal sectional view of the engine, which is a sectional view taken along line 1-1 of FIG. 3, and FIG. 2 is an upper longitudinal sectional view of the engine. 3 is a cross-sectional view taken along line 2-2 in FIG. 3, FIG. 3 is a cross-sectional view of the cylinder head taken along line 3-3 in FIG. 2, and FIG. 4 is a cross-sectional view of FIG. 4 is a plan view taken along line 4-4, FIG. 5 is a side view of the cylinder head viewed from the direction of the arrow 5 in FIG. 4, FIG. 6 is a bottom view of the cylinder head viewed from the direction of the arrow 6 in FIG. 3 is a cross-sectional view of the cylinder head taken along line 7-7 in FIG. 3, FIG. 8 is a plan view taken along arrow 8 in FIG. 1, FIG. 9 is an overall plan view of the head cover, and FIG. FIG. 11 is a cross-sectional view taken along line 11-11 in FIG. 5, and FIG. 12 is a view when the engine is cold. Cooling water system diagram showing the flow of 却水, FIG. 13 is a cooling water system diagram showing the flow of cooling water at the time between engine heat.
[0015]
1 to 6, this engine is a multi-cylinder, for example, 4-cylinder, SOHC type engine, and includes a cylinder block 21, a cylinder head 22 fastened to the upper surface of the cylinder block 21 via a gasket 24, and a cylinder A head cover 23 that is fastened to the upper surface of the head 22 via a gasket 25 and forms a valve operating chamber 26 between the head 22 and the cylinder head 22 is mounted on the vehicle.
[0016]
The cylinder block 21 is provided with four cylinder bores 27 arranged in series in a lateral direction orthogonal to the forward direction 31 of the vehicle, and the lower surface of the cylinder head 22 is slidably fitted to each cylinder bore 27. The first to fourth combustion chambers 29 </ b> A, 29 </ b> B, 29 </ b> C, and 29 </ b> D that face the tops of the pistons 28 are formed so as to be arranged in series with the cylinder block 21.
[0017]
Referring also to FIG. 7, the first to fourth combustion chambers 29 </ b> A to 29 </ b> D are disposed at the upper portion of the cylinder head 22 at the substantially central portion in the direction orthogonal to the arrangement direction of the first to fourth combustion chambers 29 </ b> A to 29 </ b> D. Are integrally provided, and circular bearing holes 33 are coaxially provided in these shaft bearing portions 32. On the other hand, a camshaft 34 having an axis extending in parallel with the arrangement direction of the first to fourth combustion chambers 29A to 29D is disposed in the valve operating chamber 26 above the combustion chambers 29A to 29D. 34 is rotatably supported by the shaft bearing portions 32. That is, the camshaft 34 is integrally provided with five circular support portions 34a, which are spaced apart in the axial direction so as to correspond to the shaft bearing portions 32, so as to project outward in the radial direction. The camshaft 34 is rotatably supported by the cylinder head 22 by inserting and supporting the support portions 34a through the bearing holes 33.
[0018]
On both sides of the cylinder head 22, projecting portions 22a and 22b projecting outward from the cylinder block 21 are integrally provided in common to the combustion chambers 29A to 29D, and the projecting portions 22a and 22b An intake side fastening surface 35, which is a flat surface parallel to the camshaft 34, is formed at the outer end of one protrusion 22 a facing the front side along the forward direction 31 of the vehicle, and the rear side along the forward direction 31 of the vehicle An exhaust side fastening surface 36 is formed as a flat surface parallel to the camshaft 34 at the outer end of the other projecting portion 22 b facing the surface.
[0019]
The cylinder head 22 is provided with one intake port 40... And one exhaust port 41... For each combustion chamber 29A to 29D, and the outer end of each intake port 40 is opened to the intake side fastening surface 35. The outer end of each exhaust port 41 is opened to the exhaust side fastening surface 36.
[0020]
An intake device 42 is fastened to the intake side fastening surface 35. The intake device 42 individually corresponds to the intake manifold 43 having a flange 43a common to the intake ports 40 and the intake ports 40. And a plate 44 that abuts against the flange 43a, and is fastened to the intake side fastening surface 35 with a gasket 45 interposed between the plate 44 and the intake side fastening surface 35. The An exhaust device (not shown) is fastened to the exhaust side fastening surface 36.
[0021]
In the cylinder head 22, intake valves 47... Interposed between the inner ends of the intake ports 40... And the combustion chambers 29 </ b> A to 29 </ b> D are disposed so as to be able to open and close, and the inner ends of the exhaust ports 41. Exhaust valves 48 interposed between .about.29D are arranged to be openable and closable.
[0022]
A valve shaft 47a of the intake valve 47 is slidably fitted to a guide cylinder 49 provided in the cylinder head 22 and protrudes into the valve operating chamber 26, and a retainer 50 provided at the upper end of the valve shaft 47a. The intake valve 47 is spring-biased in the valve closing direction by the valve spring 51 that is contracted between the cylinder heads 22. A valve shaft 48a of the exhaust valve 48 is slidably fitted into a guide cylinder 52 provided in the cylinder head 22 and protrudes into the valve operating chamber 26. A retainer provided at the upper end of the valve shaft 48a. The exhaust valve 48 is spring-biased in the valve closing direction by a valve spring 54 that is contracted between 53 and the cylinder head 22.
[0023]
A single rocker shaft 55 having an axis parallel to the camshaft 34 is disposed in the valve operating chamber 26, and this rocker shaft 55 is fixedly disposed on the cylinder head 22 above the camshaft 34. That is, the rocker shaft 55 is fastened to the upper surface of the shaft bearing portion 32 provided on the cylinder head 22 by the bolts 56 so as to rotatably support the camshaft 34.
[0024]
The intake valves 47 and the exhaust valves 48 for the respective combustion chambers 29A to 29D are arranged at positions shifted along the axes of the camshaft 34 and the rocker shaft 55. And the exhaust side cams 58 corresponding to the exhaust valves 48 are integrally provided for each of the combustion chambers 29A to 29D. Thus, the radius of the circular locus drawn by the top portions of the intake side cams 57... And the exhaust side cams 58 is set to be smaller than the radius of the support portion 34 a included in the camshaft 34. It is possible to insert and support the shaft bearing portions 32.
[0025]
The rocker shaft 55 is driven by an intake side rocker arm 59 that is driven by an intake side cam 57 of the camshaft 34 to drive an intake valve 47 and an exhaust side valve 58 of the camshaft 34 is driven by an exhaust valve 48. Exhaust-side rocker arms 60 are driven in a swingable manner.
[0026]
The intake-side rocker arm 59 includes a cylindrical boss portion 59a that is swingably supported by the rocker shaft 55, and an arm portion 59b that extends in a direction perpendicular to the axis of the rocker shaft 55 and that is integrally connected to the boss portion. A roller 61 pivotally supported on one end side of the arm portion 59b is in rolling contact with the intake side cam 57, and a tappet screw 62 screwed to the other end of the arm portion 59b so as to be able to adjust the advance / retreat position. The intake valve 47 is brought into contact with the upper end of the valve shaft 47a.
[0027]
The exhaust-side rocker arm 60 includes a cylindrical boss portion 60a supported so as to be swingable by the rocker shaft 55, and an arm portion that extends in a direction perpendicular to the axis of the rocker shaft 55 and is integrally connected to the boss portion 60a. 60b, and a roller 63 pivotally supported on one end side of the arm portion 60b is in rolling contact with the exhaust side cam 58 and screwed into the other end of the arm portion 60b so that the advance / retreat position can be adjusted. 64 is brought into contact with the upper end of the valve shaft 48 a of the exhaust valve 48.
[0028]
The intake-side rocker arm 59 and the exhaust-side rocker arm 60 have a spring 65 surrounding the rocker shaft 55 interposed between the boss portions 59a, 60a of both the rocker arms 59, 60, and the axial movement of the both boss portions 59a, 60a is a cylinder. The rocker shaft 55 is swingably mounted so as to be regulated by the shaft bearing portions 32 of the head 22, and the intake side rocker arm 59 and the exhaust side rocker arm 60 are positioned in the direction along the axis of the rocker shaft 55. Can be achieved by one spring 65, and the number of parts can be reduced as compared with the case where the springs are respectively interposed between the shaft bearing portions 32.
[0029]
Further, the boss portions 59a, 60a are formed so as to extend from the arm portions 59b, 60b to the shaft bearing portions 32, and are directly slidably contacted with the shaft bearing portions 32, so that the structure is adopted. The number of parts can be reduced as compared with those in which collars are interposed between the boss portions 59a and 60a and the shaft bearing portions 32.
[0030]
Arm portions 59b and 60b interposed between the intake side cam 57 and the exhaust side cam 58 and the intake valve 47 and the exhaust valve 48 are formed to extend in a direction perpendicular to the axis of the rocker shaft 55. The arm portions 59b and 60b to which the valve load acts can be increased in rigidity as compared with the bent arm portion, and the intake side rocker arm 59 and the camshaft 34 in the direction along the axis of the camshaft 34 can be increased. The space required for installation of the exhaust side rocker arm 60 can be kept small, which can contribute to the downsizing of the cylinder head 22 in the direction along the axis of the camshaft 34.
[0031]
In the cylinder head 22, first and second spark plugs 66, 67, which have axes arranged in a plane perpendicular to the axis of the camshaft 34, are formed in screw holes 66 a, 67 a, provided in the cylinder head 22. A first spark plug 66 arranged in each of the first to fourth combustion chambers 29 </ b> A to 29 </ b> D so as to be screwed and aligned with the exhaust valve 48 in a direction orthogonal to the axis of the camshaft 34 is provided on the camshaft 34. The second spark plug 67 arranged along the axis line with the intake valve 47 and lined with the intake valve 47 in a direction orthogonal to the axis line of the camshaft 34 is arranged with the exhaust valve 48 along the axis line of the camshaft 34. Be placed.
[0032]
That is, the first spark plug 66 aligned with the upstream end of the exhaust port 41 in a direction orthogonal to the axis of the camshaft 34 is arranged to align with the intake valve 47 along the axis of the camshaft 34, A second spark plug 67 aligned with the downstream end of the intake port 40 in the orthogonal direction is arranged to align with the exhaust valve 48 along the axis of the camshaft 34. Further, the upstream end of the intake port 40 is arranged to be deviated from the downstream end of the intake port 40 to the one side in the direction along the axis of the camshaft 34, and the downstream end of the exhaust port 41 is in the direction along the axis of the camshaft 34. The exhaust port 41 is displaced from the upstream end to the other side.
[0033]
Thus, by defining the arrangement of the intake and exhaust ports 40 and 41 and the first and second spark plugs 66 and 67, the opening area to the combustion chambers 29A to 29D at the downstream end of the intake port 40 and the exhaust port 41 Combustion efficiency can be improved by ensuring that the opening area to the combustion chambers 29A to 29D at the upstream end is as large as possible and that the intake air flow from the intake port 40 generates a swirl flow in the combustion chambers 29A to 29D. .
[0034]
Moreover, the intake ports 40 and the exhaust ports 41 are arranged at the upstream end central portion of the intake ports 40, that is, the position PI of the outer end, and the downstream end central portion of the exhaust ports 41, that is, the position PO of the outer end center. Are bent in the direction along the axis of the camshaft 34 and are provided on the cylinder head 22.
[0035]
The cylinder head 22 is integrally provided with first insertion / removal guide portions 68 for guiding insertion / removal of the first spark plugs 66 for each of the combustion chambers 29A to 29D. A second insertion / removal guide portion 69 is provided integrally for each of the combustion chambers 29A to 29D.
[0036]
The first insertion / removal guide portion 68 has an arc shape in which at least the upper portion, in this embodiment, the upper portion and the lower portion excluding the intermediate portion in the vertical direction, the opposite side to the camshaft 34 (the front side along the vehicle forward direction 31) is opened. The cylinder head 22 can be easily cast by determining the shape of the first insertion / removal guide portion 68 in this manner. Further, the second insertion / removal guide portion 69 is provided integrally with the cylinder head 22 so that at least the upper end portion thereof, in this embodiment, the entire length is cylindrical.
[0037]
With particular attention to FIG. 1, the first insertion / removal guide portion 68 and the intake valve 47 are disposed so as to overlap at least partially on a projection view on a plane orthogonal to the axis of the camshaft 34, and the second insertion / removal is performed. The guide part 69 and the exhaust valve 48 are arranged so as to overlap at least a part on the projection onto the plane. Moreover, the first and second insertions are greater than the shortest distance between at least one of the valve shafts 47a and 48a of the intake valve 47 and the exhaust valve 48 (both in this embodiment) and the camshaft 34 on the projection view. The shortest distance between at least one of the de-guide portions 68 and 69 (both in this embodiment) and the camshaft 34 is set small. That is, in this embodiment, the shortest distance between the valve shaft 47a of the intake valve 47 and the camshaft 34 on the projection view is L1, and the first insertion / removal guide portion 68 and the camshaft 34 on the projection view are L2 <L1 when the shortest distance between them is L2, and the relative positional relationship between the valve shaft 48a of the exhaust valve 48 and the second insertion / removal guide 69 and the camshaft 34 is also set. It is set similarly.
[0038]
At least one of the upper end portions of the first and second insertion / removal guide portions 68 and 69, in this embodiment, both are bent and formed so as to protrude into the valve operating chamber 26 between the cylinder head 22 and the head cover 23. .
[0039]
With particular attention to FIG. 4, the cylinder head 22 is fastened to the cylinder block 21 by a plurality of head bolts 70, for example, five bolts arranged on both sides at intervals in the axial direction of the camshaft 34. Between the head bolts 70 and at least one of the intake valves 47 and the exhaust valves 48 (both in this embodiment), at least a part of the first and second insertion / removal guide portions 68, 69,. In the space between the intake and exhaust valves 47, 48, and the head bolts 70 arranged on the side thereof, at least one of the first and second insertion / removal guide portions 68, 69,. It is possible to contribute to the compactness of the cylinder head 22 in the width direction perpendicular to the axis of the camshaft 34 by effectively arranging a part thereof by bending.
[0040]
Further, the first and second insertion / removal guide portions 68 are disposed between at least one of the intake valves 47 and the exhaust valves 48 and the head bolts 70 adjacent to at least one of the intake valves 47 and the exhaust valves 48. , 69... Are arranged at least in part. Thus, in this embodiment, a part of the first insertion / removal guide portion 68 is disposed between the intake valve 47 and the head bolt 70 adjacent to the intake valve 47, and the exhaust valve 48 and the exhaust valve 48 are connected to each other. A part of the second insertion / removal guide portion 69 is disposed between the adjacent head bolts 70. Thereby, a part of the first and second insertion / removal guide portions 68, 69,... Is effectively placed in the space between the intake valve 47 and the exhaust valve 48 and the head bolts 70 disposed on the side thereof. The arrangement can contribute to making the cylinder head 22 compact in the axial direction of the camshaft 34.
[0041]
Further, at least a part of at least one of the first and second insertion / removal guide portions 67, 68 ... between the shaft bearing portion 32 ... of the cylinder head 22 and at least one of the intake valve 47 ... and the exhaust valve 48 .... Is placed. Thus, in this embodiment, a part of the first insertion / removal guide portion 68 is disposed between the shaft bearing portion 32 and the intake valve 47, and the first insertion / removal guide portion 68 is disposed between the shaft bearing portion 32 and the exhaust valve 48. A part of the two insertion / removal guide portions 69 is arranged, and according to such an arrangement, the first space is formed between the intake valves 47 and the shaft bearing portions 32 arranged on the side thereof. A portion of the insertion / removal guide portion 68 is effectively disposed, and the second insertion / removal guide portion 69 is disposed in a space between the exhaust valve 48 and the shaft bearing portion 32 disposed on the side thereof. The cylinder head 22 can be made more compact in the axial direction of the camshaft 34 by arranging a part effectively.
[0042]
Further, the upper portions of the first and second insertion / removal guide portions 68... 69 are bent so as to project toward the valve operating chamber 26, and these projecting portions are formed on the cylinder head 22. The intake side cams 57 and the exhaust side cams 58 partially immersed in the oil bath 71 (see FIGS. 1 and 2), and the rollers 61 provided in the intake side rocker arms 59 and the exhaust side rocker arms 60, respectively. ..., 63 ... are arranged at positions corresponding to the contact portions.
[0043]
For this reason, the oil in the oil bath 71 is moved by the exhaust cams 58 in accordance with the rotation of the camshaft 34 in the rotation direction 72 indicated by the arrows in FIGS. The oil collides with the projecting portion toward the chamber 26 and the oil is effectively scattered in the valve operating chamber 26. Moreover, the projecting portions of the first and second insertion / removal guide portions 68... 69 to the valve chamber 26 side are intake side cams 57 and exhaust side cams 58 and rollers 61 of the intake side rocker arms 59. Since the exhaust side rocker arm 60 is located at a position corresponding to the contact portion with the roller 63, the oil scattered in the valve operating chamber 26 collides with the overhang portions and is efficiently supplied to the contact portion side. As a result, effective lubrication becomes possible.
[0044]
The first and second spark plugs 66 and 67 are attached to lower ends of rod-shaped first and second plug holders 73 and 74 that are removably inserted into the first and second insertion / removal guide portions 68 and 69, respectively. The
[0045]
The first insertion / removal guide portion 68 has a cylindrical portion 68a at the middle in the vertical direction, and the first plug holder 73 intermediates the seal portion 73a that elastically contacts the entire inner circumference of the cylindrical portion 68a. And the upper portion of the first plug holder 73 protrudes from the cylinder head 22. The second plug holder 74 is inserted into a cylindrical second insertion / removal guide portion 69. On the other hand, the head cover 23 is provided with a cylindrical portion 75... Which has a cylindrical shape and a lower end coaxially connected to the upper end of a second insertion / removal guide portion 69 provided in the cylinder head 22 in a cylindrical shape. The second plug holders 74 are inserted into the cylindrical portions 75 above the portions 69.
[0046]
8 and 9 together, ignition coils 76 are individually connected to the upper ends of the first plug holders 73 that are inserted into the first insertion / removal guides 68 and protrude upward from the cylinder head 22. Each of the combustion chambers 29A to 29D is fastened to the head cover 23 with one coil bolt 77.
[0047]
Thus, the upper portions of the first plug holders 73 project upward from the cylinder head 22, and when the ignition coils 76 are fastened to the head cover 23 with the coil bolts 77, the first plug holders 73. In order to prevent an excessive load from being applied to the protruding portion due to the force that rotates in the tightening direction of the coil bolts 77... The rotation stoppers 78 that come into contact with the outer periphery of the upper ends of the one plug holders 73 are integrally provided in a cylindrical shape through which the upper ends of the first plug holders 73 are inserted, for example. Therefore, the workability of attaching the ignition coils 76 can be improved, and an increase in the number of parts for preventing rotation can be avoided.
[0048]
Thus, the upper part of the first insertion / removal guide portions 68, into which the first plug holders 73 are inserted, is located on the front side along the forward direction 31 of the vehicle so that the upper parts of the first plug holders 73 are exposed to the outside. The cross-sectional shape of the circular arc is open to the upper side of the first plug holder 73, so that the traveling wind accompanying the forward movement of the vehicle directly hits the first plug holder 73. It will be cooled.
[0049]
On the other hand, ignition coils 79 individually connected to the upper ends of the second plug holders 74 are fastened to the head cover 23 by one coil bolt 80 for each of the combustion chambers 29A to 29D. Thus, since the upper part of the second plug holders 74 is inserted into the cylindrical parts 75 of the head cover 23, the force applied to the upper parts of the second plug holders 74 when the coil bolts 80 are tightened is the cylindrical part. It can be received at 75 ... The second plug holders 74 are cylindrical and covered from the outside with second insertion / removal guide portions 69 and cylindrical portions 75 that are connected to each other. The cylindrical portions 75 are formed of an exhaust device and an ignition coil (not shown). 79... Are adversely affected by the heat radiation from the exhaust device to the second plug holders 74 and the ignition coils 79.
[0050]
By the way, the head cover 23 is fastened to the cylinder head 22 at a plurality of places, for example, seven places spaced in the circumferential direction, and bolts 82 inserted through insertion holes 81 provided in the head cover 23 are cylinders. Screwed into screw holes 83 provided on the upper surface of the head 22.
[0051]
Of the insertion holes 81, bolts 82, and screw holes 83 arranged at a plurality of locations, for example, the three insertion holes 81, bolts 82, and screw holes 83 are formed between the rotation stoppers 79, respectively. Is arranged. As a result, the portion provided on the cylinder head 22 side in order to fasten the head cover 23 to the cylinder head 22 does not protrude from the side surface of the cylinder head 22 to the side as much as possible, thereby contributing to the compactness of the cylinder head 22. It is possible to prevent an excessive load from acting on the first plug holders 73 while reducing the weight of the cylinder head 22.
[0052]
In addition, each of the anti-rotation portions 79..., The three insertion holes 81... Disposed between the anti-rotation portions 79 are provided in the to-be-fastened portions 84 directly connected to the three anti-rotation portions 79. The rigidity of the stoppers 79 can be increased.
[0053]
Of the insertion holes 81, bolts 82, and screw holes 83, for example, two insertion holes 81, bolts 82, and screw holes 83 are formed between the second insertion / removal guide portions 69 that are cylindrical. Placed in. Also by this, the portion provided on the cylinder head 22 side for fastening the head cover 23 to the cylinder head 22 is prevented from protruding sideways as much as possible from the side surface of the cylinder head 22, thereby further contributing to the compactness of the cylinder head 22. be able to.
[0054]
Incidentally, the head cover 23 has a protruding portion 23a protruding from the cylinder head 22 at one end side along the axial direction of the camshaft 34, and this protruding portion 23a is a chain cover (not shown) that covers the power transmission mechanism. ). Thus, an oil supply cylinder 86 that is detachably closed by an oil filler cap 85 is integrally provided at the protruding portion 23 a so as to protrude upward, and a fastening boss portion disposed on both sides of the oil supply cylinder 86. 87 and 87 are integrally provided, and bolts 88 and 88 inserted into the fastening boss portions 87 and 87, respectively, are screwed into the chain cover. Therefore, the detachability of the oil filler cap 85 can be improved, and the fastening rigidity of the head cover 23 and the chain cover can be increased by the highly rigid oil supply tube 86.
[0055]
Moreover, ribs 90, 90 connecting the oil supply cylinder 86 and both fastening boss portions 87, 87 are integrally formed on the upper surface of the protruding portion 23a, and these ribs 90, 90 allow the oil supply cylinder 86 and both fastening bosses to be formed. The rigidity of the parts 87 and 87 will increase. The cylinder head 22 is provided with a first EGR passage 94 extending in a direction perpendicular to the axis of the camshaft 34 on one end side along the axis of the camshaft 34, and one end of the first EGR passage 94 is connected to the cylinder head 22. The other end of the first EGR passage 94 opens to the intake side fastening surface 35 through a communication hole 95 provided in the first combustion chamber 29A.
[0056]
Thus, the first EGR passage 94 is disposed at a position where the exhaust port 41 of the first combustion chamber 29A is sandwiched between the second insertion / removal guide portion 69 of the first combustion chamber 29A, that is, the second spark plug 67. The communication structure between the exhaust port 41 and the first EGR passage 94 can be simplified by allowing the exhaust port 41 to communicate with the first EGR passage 94 through the communication hole 95 extending linearly. . The first EGR passage 94 is arranged at a position where the first insertion / removal guide portion 68 of the first combustion chamber 29A, that is, the first spark plug 66 is sandwiched between the intake port 40 and the intake port 40. It is possible to suppress the adverse effect due to the heat from the first EGR passage 94 on the circulating air.
[0057]
In FIG. 10, a passage member 97 having an inlet side passage 96 communicating with the first EGR passage 94 is fastened to the intake side fastening surface 35 on one end side along the axial direction of the camshaft 34. An EGR valve 99 that controls the flow of EGR gas between the inlet side passage 96 and the outlet side passage 98 provided in the passage member 97 is attached to the passage member 97. That is, an EGR valve 99 for controlling the flow of EGR gas is attached to the side wall of the cylinder head 22 on the side where the upstream end of the intake port 40 opens, and the intake port 40 of the first combustion chamber 29A is connected to the first combustion chamber. 29A is disposed between the first insertion / removal guide portion 68, that is, the first spark plug 66 and the EGR valve 99. This also can prevent the air flowing through the intake port 40 of the first combustion chamber 29A from being adversely affected by the heat from the EGR valve 99.
[0058]
With further reference to FIG. 11, the cylinder head 22 is connected to the outlet side passage 98 of the passage member 97 at a portion corresponding to the passage member 97 so as to open the outer end of the intake side fastening surface 35. 100 and a second EGR passage 101 communicating with the inner end of the communication hole 100 are provided. The second EGR passage 101 extends from a portion near one end of the cylinder head 22 along the axial direction of the cam shaft 34 to a substantially central portion of the cylinder head 22 along the axial direction of the cam shaft 34. It is formed so as to extend in parallel, and most of it is opened to the intake side fastening surface 35. However, most of the opening of the second EGR passage 101 to the intake side fastening surface 35 is closed by a gasket 45 sandwiched between the intake side fastening surface 35 and the plate 44.
[0059]
On the other hand, the projecting portion 22a of the cylinder head 22 is provided with a boss 103 for attaching a fuel injection valve 102 for injecting fuel to each intake port 40, and the second EGR passage 102 is connected to the cylinder head. In order to further contribute to the downsizing of the fuel tank 22, the space corresponding to the first and second combustion chambers 29 </ b> A and 29 </ b> B is effectively disposed in the space between the intake port 40 and the fuel injection valve 102.
[0060]
Moreover, the second EGR passage 101 extends in parallel with the axis of the camshaft 34 in the vicinity of the fuel injection valve 102 corresponding to the first and second combustion chambers 29A and 29B, and the first and second combustion chambers 29A. , 29B, a part of the boss 103 provided in the cylinder head 22 for mounting the fuel injection valve 102 at the portion corresponding to 29B enters into the second EGR passage 101 as the entry portion 103a.
[0061]
On the other hand, a recess 108 opened in the intake side fastening surface 35 on the extension of the inner end portion of the second EGR passage 101 and closed by the gasket 45 is provided in the cylinder head 22 for weight reduction. A part of the boss 103 provided on the cylinder head 22 for attaching the fuel injection valve 102 at a portion corresponding to the combustion chamber 29C enters into the recess 108 as an entry portion 103b in order to ensure the thickness.
[0062]
With particular attention to FIG. 10, the gasket 45 that contacts the intake side fastening surface 35 is provided with a communication passage 104 that communicates with the inner end of the second EGR passage 101, and the gasket 45 is connected to the intake side fastening surface 35. On the surface of the plate 44 sandwiched between them, there are provided a common groove 105 extending to the left and right sides through the central portion of the communication path 104, and branch grooves 106, 106 connected to both ends of the common groove 105. . Thus, one end portion of the common groove 105 is set at a position corresponding to the space between the intake ports 40 and 40 of the first and second combustion chambers 29A and 29B, and the other end portion of the common groove 105 is third and third. The four combustion chambers 29 </ b> C and 29 </ b> D are set at positions corresponding to the intake ports 40 and 40, and one branch groove 106 extends from one end of the common groove 105 to the intake ports 40 of the first and second combustion chambers 29 </ b> A and 29 </ b> B. The other branch groove 106 is formed so as to extend from the other end of the common groove 105 toward the intake ports 40, 40 of the third and fourth combustion chambers 29C, 29D.
[0063]
In addition, the portion of the common groove 105 other than the portion corresponding to the communication path 104 and most of the branch grooves 106 and 106 are closed by the gasket 45 sandwiched between the intake side fastening surface 35 and the plate 44. The gasket 45 is provided with passages 107 that individually communicate with the intake ports 40 so as to include notches 107a that communicate with the passages 107 through the ends of the 106 and 106, respectively. At the opening end to the intake side fastening surface 35 of 40 ..., a notch 40a ... communicating with the notch 107a ... is provided so as to continue to the intake port 40 ....
[0064]
That is, the exhaust port 41 of the first combustion chamber 29A is led to the second EFR passage 101 through the communication hole 95, the first EGR passage 94, the inlet side passage 96, the EGR valve 99, the outlet side passage 98 and the communication hole 100. The EGR gas is guided from the communication passage 104 of the gasket 45 to the common groove 105, and further branched into a pair of branch grooves 106, 106 from the notches 107a ..., 40a ... to the intake ports 40 of the combustion chambers 29A-29D. Will be distributed.
[0065]
A spark plug chamber 109A, 109B, 109C, 109D corresponding to each of the combustion chambers 29A to 29D with a part of the first spark plug 66 facing the cylinder head 22 is aligned with the protruding portion 22a of the cylinder head 22. The opening portion of each spark plug chamber 109A, 109B, 109C, 109D to the intake side fastening surface 35 is closed by a gasket 45. Moreover, the spark plug chambers 109A and 109B are formed in the cylinder head 22 so as to be interposed between the combustion chambers 29A and 29B and the second EGR passage 101.
[0066]
By the way, the first spark plug 66 has a seal portion 73 a that elastically contacts the cylindrical portion 68 a of the intermediate portion of the first insertion / removal guide portion 68 and is inserted into the first insertion / removal guide portion 68. Although attached to the lower end of the plug holder 73, a complete seal by the seal portion 73a cannot be obtained, and the spark plug chambers 109A, 109B, 109C, 109D from between the seal portion 73a and the cylindrical portion 68a are not provided. It is hard to avoid entering water.
[0067]
Therefore, the drain holes 110A, 110B, 110C, 110D for draining the water that has entered the spark plug chambers 109A to 109D open at one end to the lower part of the spark plug chambers 109A to 109D and the other end at the protruding portion 22a. The cylinder head 22 is provided with a protrusion 22 a so as to open to the lower outer surface of the cylinder head 22.
[0068]
In the portion corresponding to the third combustion chamber 29C, the cylinder head 22 has a bag hole-like fastening boss 111 for fastening the intake device 42 to the protrusion 22a with one of the plurality of fastening bosses 115. It is provided so as to enter the lower part in 109C. In addition, the position of the drain hole 110 </ b> C is set so that one end is opened at the lower portion of the spark plug chamber 109 </ b> C between the spark plug 66 and the fastening boss 111 in the direction along the axis of the camshaft 34.
[0069]
According to such an arrangement of the fastening boss 111 and the drain hole 110C, an increase in the size of the cylinder head 22 can be avoided. That is, when the fastening boss is disposed at a position shifted from the ignition plug chamber 109C, the cylinder head is inevitably enlarged. However, the cylinder head 22 can be enlarged by inserting the fastening boss 111 into the lower portion of the ignition plug chamber 109C. It can be avoided. Moreover, the water that has entered the spark plug chamber 109C from around the first spark plug 66 can be guided to the drain hole 110C side so that the fastening boss 111 does not get in the way.
[0070]
A fastening boss 112 for fastening the intake device 42 to the projecting portion 22a is provided in the cylinder head 22 at a portion corresponding to the first combustion chamber 29A so as to enter the lower portion in the spark plug chamber 109C. In addition, one end of a drain hole 110A is opened at the lower portion of the spark plug chamber 109A at a position sandwiching the fastening boss 112 between the first spark plug 66 in the direction along the axis of the camshaft 34, and the spark plug chamber 109A A guide wall 113 is provided between the inner wall and the fastening boss 112 to guide water that has entered the periphery of the first spark plug 66 toward the drain hole 110A.
[0071]
The arrangement of the fastening boss 112, the drain hole 110C, and the guide wall 113 can also prevent the cylinder head 22 from becoming large, and the water that has entered the spark plug chamber 109A from around the first spark plug 66 can be prevented. The fastening boss 112 can be guided to the drain hole 110A side by the guide wall 113 so that the fastening boss 112 does not get in the way, and the rigidity of the fastening boss 112 can be increased by the guide wall 113.
[0072]
Further, the fastening boss 112 and the guide wall 113 form a flat surface 114 parallel to the camshaft 34 and positioned below the inner surface of the spark plug chamber 109A on the projecting end of the projecting portion 22a, that is, on the intake side fastening surface 35 side. A screw hole 116 for screwing the fastening bolt 115 is provided between the intake side fastening surface 35 and the flat surface 114.
[0073]
Therefore, the water that has entered the spark plug chamber 109A from around the first spark plug 66 can be guided to the drain hole 110A side by the flat surface 114 so that the fastening portion of the fastening bolt 115 does not get in the way.
[0074]
Referring to FIGS. 12 and 13 together, the cylinder head 22 is provided with a head-side water jacket 118 that communicates with a block-side water jacket 119 provided in the cylinder block 21. A port 120 that communicates with the head-side water jacket 118 on the end side is connected to the heater core 122 via a pipe 121. A thermostat 126 is mounted in a mounting recess 134 (see FIG. 3) provided in the cylinder head 22 at the other axial end of the camshaft 34, and the heater core 122 is connected to the thermostat 126 via a pipe 123. The head side water jacket 118 in the cylinder head 22 is also connected to the thermostat 126 through the bypass passage 133.
[0075]
One end of a pipe line 125 is connected to the port 120, and the pipe line 125 is connected to a pipe line 136 after supplying warm water to an auxiliary machine such as the throttle body 124 at an intermediate portion. One end of this pipe line 136 is connected to the port 135 provided in the cylinder head 22 and is connected to the outlet side of the thermostat 126, and the other end of the pipe line 136 is connected to the suction side of the water pump 131. . Further, a pipe line 132 for guiding a part of the cooling water from the head side water jacket 118 of the cylinder head 22 is also connected to the suction side of the water pump 131. Thus, the discharge side of the water pump 31 is connected to the head side water jacket 118 of the cylinder head 22.
[0076]
Further, the cylinder head 22 is provided with a port 127 that communicates with the block-side water jacket 119 of the cylinder block 21, and this port 127 is connected to the inlet side of the radiator 129 through the pipe 128 and is connected to the outlet side of the radiator 129. Is connected to the thermostat 126 via a conduit 130.
[0077]
In such a cooling water circuit, the thermostat 126 shuts off the pipe 136 and the pipe 130 when the engine is cold, and causes the pipe 123 and the bypass passage 133 to communicate with the pipe 136. Most of the cooling water supplied from 131 to the head-side water jacket 118 is sent to an auxiliary machine such as the heater core 122 and the throttle body 124 as shown by solid line arrows in FIG. 12, and the cooling water is supplied to the radiator 129. Will not be supplied.
[0078]
On the other hand, the thermostat 126 shuts off the bypass passage 133 and the conduit 130 when the engine is hot, and connects the conduits 123 and 130 to the conduit 136, so that the water pump 131 connects to the head side water jacket 118. The supplied cooling water is sent to the auxiliary machine such as the heater core 122 and the throttle body 124 as shown by the solid line arrow in FIG. 13 and is supplied to the block-side water jacket 119. Cooling water cooled by being sent from 119 to the radiator 129 is sucked into the water pump 131.
[0079]
Next, the operation of this embodiment will be described. The intake side rocker arm 59 that drives the intake valve 47 following the intake side cam 57 provided on the camshaft 34 and the exhaust side cam 58 provided on the camshaft 34 are described below. A single rocker shaft 55 that commonly supports the exhaust-side rocker arm 60 that drives the exhaust valve 48 to be driven is fixed to the cylinder head 22 above the camshaft 34 to guide insertion / removal of the first spark plug 66. The first insertion / removal guide portion 68 and the intake valve 47 that are arranged at least partially overlap each other on a projection view on a plane orthogonal to the axis of the camshaft 34, and guide the insertion / removal of the second spark plug 67. The insertion / removal guide part 69 and the exhaust valve 48 are arranged so as to overlap at least partially on the projection onto the plane.
[0080]
Therefore, the intake valve 47 and the first insertion / removal guide portion 68, and the exhaust valve 48 and the second insertion / removal guide portion 69 can be arranged close to the camshaft 34 side, and are orthogonal to the axis of the camshaft 34. The width of the cylinder head 22 in this direction can be set smaller than that of a conventional SOHC engine having a pair of rocker shafts.
[0081]
In addition, the first and second insertion / removal guide portions 68 and 69 are located closer than the shortest distance L1 between at least one of the valve shafts 47a and 48a of the intake valve 47 and the exhaust valve 48 and the camshaft 34 on the projection view. Since the shortest distance L2 between at least one and the camshaft 34 is set small, at least one of the first and second insertion / removal guide portions 68 and 69 is arranged closer to the camshaft 34 side, The width of the cylinder head in the direction perpendicular to the axis of the camshaft 34 can be set smaller, and the valve shafts 47a and 48a of the intake valve 47 and the exhaust valve 48 and the camshaft 34 can be set as in this embodiment. By setting the shortest distance L2 between the first and second insertion / removal guide portions 68 and 69 and the camshaft 34 to be smaller than the shortest distance L1 between the first and second It is possible to further reduce the width of the cylinder head 22 in the direction perpendicular to the axis of the camshaft 34 by arranging the two insertion / removal guide portions 68 and 69 closer to the camshaft 34 side. It becomes.
[0082]
In addition, since the upper ends of the first and second insertion / removal guide portions 68 and 69 that are integral with the cylinder head 22 are formed so as to protrude into the valve operating chamber 26, the first and second insertion / removal portions are formed. The amount of protrusion of the upper ends of the guide portions 68 and 69 from the side surface of the cylinder head 22 to the outside can be reduced, contributing to the compactness of the cylinder head 22 and the rigidity of the upper end portion of the side wall of the cylinder head 22. In addition, the ignitability can be improved by suppressing the inclination of the first and second spark plugs 66 and 67 to be small.
[0083]
Further, the cylinder head 22 is provided with a boss 103 for attaching a fuel injection valve 102 for injecting fuel into the intake port 40. A second EGR passage 101 for guiding EGR gas is provided in the vicinity of the fuel injection valve 102. The fuel injection valve 102 extends parallel to the axis of the camshaft 34 and is provided in the cylinder head 22 with a part of the boss 103 being inserted into the cylinder head 22 while ensuring the thickness of the boss 103 on the second EGR passage 101 side. The second EGR passage 101 can be provided in the cylinder head 22 in the vicinity of the fuel injection valve 102, ensuring the rigidity of the boss 103 and adversely affecting the fuel injection valve 102 due to the high temperature EGR gas flowing through the second EGR passage 101. The second EGR passage 101 is disposed in the vicinity of the fuel injection valve 102 while suppressing the cylinder head 22 so that the cylinder head 22 can be made compact. Can.
[0084]
Further, the position P1 of the upstream end central portion of the intake port 40 provided in the cylinder head 22 and the position PO of the downstream end central portion of the exhaust port 41 are set to be the same in the direction along the axis of the camshaft 34, The interval between the cylinders of the multi-cylinder engine can be set short, and the cylinder head 22 can be downsized in the direction along the axis of the camshaft 34.
[0085]
Further, the cylinder head 22 is integrally provided with a protruding portion 22a that protrudes outward from the cylinder block 21, and the ignition corresponding to each of the combustion chambers 29A to 29D with a part of the first spark plug 66 facing. Plug chambers 109A, 109B, 109C, and 109D are formed in the cylinder head 22 so as to be partially disposed on the protruding portion 22a, and the cylinder head 22 is set by setting the volumes of the spark plug chambers 109A to 109D to be relatively large. It is possible to reduce the weight.
[0086]
In addition, drain holes 110A, 110B, 110C having one end opened to the lower part of the spark plug chambers 109A to 109D and the other end opened to the lower outer surface of the projecting portion 22a, that is, outside the cylinder block 21, to the lower outer surface of the cylinder head 22. Since 110D is provided in the cylinder head 22, the water that has entered the spark plug chambers 109A to 109D can be surely discharged by the drain holes 110A to 110D that are shortened and simplified.
[0087]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.
[0088]
For example, in the above-described embodiment, the engine in which the spark plug chamber is provided in the protrusion 22a on the intake device 42 side in the cylinder head 22 has been described. However, the present invention is not limited to the engine in which the spark plug chamber is provided in the protrusion 22b on the exhaust device side. The invention can also be applied.
[0089]
【The invention's effect】
As described above, according to the present invention, the volume of the spark plug chamber can be set to be relatively large to reduce the weight of the cylinder head. The water that has entered the spark plug chamber can be reliably discharged.
[0090]
In particular , according to the first aspect of the present invention, the water that has entered the spark plug chamber from around the spark plug plug is guided to the drain hole side so that the fastening boss does not get in the way while avoiding an increase in the size of the cylinder head. be able to.
[0091]
In particular , according to the invention of claim 2 , the water that has entered the spark plug chamber from around the spark plug is guided to the drain hole side so that the fastening boss does not get in the way while avoiding an increase in the size of the cylinder head. In addition, the rigidity of the fastening boss can be increased by the guide wall.
[0092]
In particular , according to the invention of claim 3 , water that has entered the spark plug chamber from around the spark plug can be guided to the drain hole side with a flat surface while avoiding an increase in the size of the cylinder head.
[Brief description of the drawings]
FIG. 1 is an upper longitudinal sectional view of an engine, and is a sectional view taken along line 1-1 of FIG.
FIG. 2 is an upper longitudinal sectional view of the engine, and is a sectional view taken along line 2-2 of FIG.
3 is a cross-sectional view of the cylinder head taken along line 3-3 in FIG.
4 is a plan view taken along line 4-4 of FIG. 1 for showing the configuration of the valve operating chamber. FIG.
5 is a side view of the cylinder head viewed from the direction of arrow 5 in FIG.
6 is a bottom view of the cylinder head viewed from the direction of arrow 6 in FIG.
7 is a cross-sectional view of the cylinder head taken along line 7-7 in FIG.
FIG. 8 is a plan view taken along arrow 8 in FIG. 1;
FIG. 9 is an overall plan view of the head cover.
FIG. 10 is a view for explaining the flow of EGR gas between the intake side fastening surface, the gasket, and the plate of the cylinder head.
11 is a cross-sectional view taken along line 11-11 in FIG.
FIG. 12 is a cooling water system diagram showing a flow of cooling water when the engine is cold.
FIG. 13 is a cooling water system diagram showing a flow of cooling water when the engine is hot.
[Explanation of symbols]
21 ... cylinder block 22 ... cylinder head 22a ... projecting parts 34 camshaft 42 ... intake device 66 ... spark plug 109 A, 109 C ... spark plug chamber 110 A, 110 C: Drain holes 111, 112 ... Fastening boss 113 ... Guide wall 114 ... Flat surface 115 ... Fastening bolt 116 ... Screw hole

Claims (3)

The cylinder head (22) fastened to the cylinder block (21) is integrally provided with a protrusion (22a) protruding outward from the cylinder block (21), and is orthogonal to the axis of the camshaft (34). In an engine to which a spark plug (66) having an axis arranged in a plane is mounted,
Said ignition plug (66) of the spark plug chamber for exposing a part (109 C), formed in the cylinder head (22) so as to place the part on the projecting portion (22a) Rutotomoni, intake system ( 42) or a fastening boss (111) for fastening the exhaust device to the protrusion (22a) is provided in the cylinder head (22) so as to protrude into the lower part of the spark plug chamber (109C),
A drain hole (110 C ) having one end opened at a lower portion in the spark plug chamber (109 C ) between the spark plug (66) and the fastening boss (111) in a direction along the axis of the camshaft (34). , Provided in the protrusion (22a) ,
Engine, characterized in that the other end of the water drain hole (110C) is opened to the lower outer surface of the projecting portion (22a). The cylinder head (22) fastened to the cylinder block (21) is integrally provided with a protrusion (22a) protruding outward from the cylinder block (21), and is orthogonal to the axis of the camshaft (34). In an engine to which a spark plug (66) having an axis arranged in a plane is mounted,
A spark plug chamber (109A) that faces a part of the spark plug (66) is formed in the cylinder head (22) so as to be partially disposed in the projecting part (22a), and an intake device (42). ) Or a fastening boss (112) for fastening the exhaust device to the protrusion (22a ) is provided in the cylinder head (22) so as to protrude into the lower part of the spark plug chamber (109A),
In the direction along the axis of the camshaft (34), the fastening boss (112) is sandwiched between the spark plug (66) and the projecting portion (22a) at the lower part in the spark plug chamber (109A). One end of the provided drain hole (110A) opens , and the other end of the drain hole (110A) opens to the lower outer surface of the protrusion (22a),
Between the inner wall of the spark plug chamber (109A) and the fastening boss (112), there is provided a guide wall (113) for guiding the water that has entered the periphery of the spark plug (66) to the drain hole (110A) side. d and wherein the engine. The cylinder head (22) fastened to the cylinder block (21) is integrally provided with a protrusion (22a) protruding outward from the cylinder block (21), and is orthogonal to the axis of the camshaft (34). In an engine to which a spark plug (66) having an axis arranged in a plane is mounted,
A spark plug chamber (109A) that faces a part of the spark plug (66) is formed in the cylinder head (22) so as to be partially disposed in the projecting part (22a), and the projecting part ( 22a) is provided with a drain hole (110A) having one end opened in the lower part of the spark plug chamber (109A) and the other end opened in the lower outer surface of the protrusion (22a),
At least the lower part of the inner surface of the spark plug chamber (109A) on the projecting end side of the projecting portion (22a) is formed on a flat surface (114) parallel to the camshaft (34),
A screw hole (116) for screwing a fastening bolt (115) for fastening the intake device (42) or the exhaust device is provided between the protruding end surface of the protruding portion (22a) and the flat surface (114). d and wherein the engine.

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