JP2004316633A - Cylinder head of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder head of an internal combustion engine capable of increasing the engine output, enhancing ignitability, and reducing the weight of the internal combustion engine by reducing the inclination when an ignition plug is arranged in an inclined manner. <P>SOLUTION: The cylinder head 21 of the internal combustion engine E has an insertion hole 31 in which an ignition plug 30 facing a substantially center part of a combustion chamber 27 is inserted, a first bearing part 51 to support one end part 41a of a single cam shaft 41, and a joining surface 23 with a cylinder head cover 22 coupled therewith via a seal member 24. The first bearing part 51 overlaps the insertion hole 31 in plan view, and is located between the insertion hole 31 and the joining surface 23 in the cylinder axial direction A1, and constituted of a side wall 54 of the cylinder head 21 to cover the entire end face 41a1 of one end part 41a. The ignition plug 30 or a plug cap 56 is at the position overlapping the first bearing part 51 when viewed from the axial direction A2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cylinder head of an internal combustion engine in which an insertion hole for a spark plug and a bearing portion rotatably supporting a single cam shaft for opening and closing an intake valve and an exhaust valve are formed.

  2. Description of the Related Art As a cylinder head for an internal combustion engine of this type, for example, one disclosed in Patent Document 1 is known. An ignition plug is mounted on the cylinder head so that the electrode portion is located substantially at the center of the combustion chamber so that combustion in the combustion chamber proceeds uniformly and quickly, and an insertion hole into which the ignition plug is inserted is provided. , Are formed to be inclined with respect to the cylinder axis in a side view. Further, a pair of head-side bearing halves rotatably supporting a camshaft arranged offset in a direction opposite to the inclination direction of the insertion hole with respect to the cylinder axis in a side view is a cylinder head cylinder. The opening is formed on the mating surface with the head cover. The pair of head-side bearing halves cooperate with the pair of cover-side bearing halves formed on the cylinder head cover to form a pair of bearings that support the camshaft.

Microfilm of Japanese Utility Model Application No. 62-94080 (Japanese Utility Model Application Laid-Open No. 63-202707) (Fig. 1)

  By the way, in order to prevent the tip of the spark plug from which the electrode is protruded and exposed to the high-temperature combustion gas to prevent overheating, the tip hardly projects or slightly projects into the combustion chamber. In this case, when the inclination of the insertion hole into which the ignition plug is inserted increases, the volume of the space portion of the insertion hole not occupied by the ignition plug increases, and accordingly, the volume of the combustion chamber increases and the compression ratio decreases. As a result, the engine output is reduced, and the electrode occupies a position retreated from the combustion chamber into the insertion hole, and the ignitability is reduced. Therefore, it is desirable that the inclination of the insertion hole be as small as possible.

  On the other hand, a sealing member is provided between the mating surface of the cylinder head and the mating surface of the cylinder head cover, and a band-shaped sealing area is provided on both mating surfaces to seal the gap between the two mating surfaces. There is a need to. Then, as in the prior art described above, in which each bearing portion is composed of a head-side bearing portion half and a head cover-side bearing portion half, both mating surfaces are present at positions overlapping the camshaft in the cylinder axis direction. In the head, each bearing portion projects in the axial direction of the camshaft because the mating surface has a sealing area for ensuring a required sealing property.

  Therefore, in the prior art, when the inclination of the insertion hole is reduced, the projection of the bearing portion near the ignition plug interferes with the ignition plug or the plug cap attached to the ignition plug. Thus, it has been difficult to reduce the inclination of the spark plug.

  Further, in the pair of bearing portions, it is necessary to stably support the rotating camshaft while receiving the reaction force from the intake valve and the exhaust valve. However, when the bearing portion is bisected by the mating surface, if the thickness of the wall of the bearing portion is increased to secure rigidity for stably supporting the camshaft, the bearing portion moves toward the spark plug. Further overhanging makes it more difficult to reduce the inclination of the spark plug.

  The present invention has been made in view of such circumstances, and the inventions according to claims 1 to 3 have the following advantages. An object is to improve the ignitability and to reduce the weight of the internal combustion engine. The second and third aspects of the invention further aim at reducing the size of the cylinder head, and the fourth aspect of the invention further reduces the size of the area around the cylinder head on which the fuel injection valve is mounted. It also aims to increase the engine output.

  The invention according to claim 1 is a cylinder head of an internal combustion engine coupled to a cylinder, wherein an insertion hole into which a spark plug having an electrode portion facing a substantially central portion of a combustion chamber is inserted, and an intake valve and an exhaust valve. Internal combustion having a first bearing portion and a second bearing portion rotatably supporting a single camshaft provided with an opening and closing valve cam, and a mating surface to which a cylinder head cover is coupled via a seal member. In the cylinder head of the engine, the first bearing portion supporting one end of the cam shaft is located at a position overlapping the insertion hole in a plan view, and is located between the insertion hole and the mating surface in the cylinder axis direction. And the side wall of the cylinder head in the axial direction of the camshaft, covers the entire end surface of the one end, and is attached to the spark plug or the spark plug when viewed from the axial direction. Plug cap is a cylinder head of an internal combustion engine that overlaps with the first bearing portion.

  According to this, since the first bearing portion constituted by the side wall between the insertion hole and the mating surface in the cylinder axis direction does not have the mating surface, it is not necessary to provide a seal area for ensuring the sealing performance. The amount of protrusion toward the spark plug or the plug cap provided at a position overlapping the first bearing portion when viewed from the axial direction is suppressed, and the inclination of the insertion hole with respect to the cylinder axis in a side view, and thus the inclination of the spark plug and the plug cap. Can be reduced. Further, in the first bearing portion, it is not necessary to increase the thickness of the side wall for increasing the support rigidity of the cam shaft, which is required when the bearing portion is divided.

  According to a second aspect of the present invention, in the cylinder head of the first aspect, the intake valve and the exhaust valve are provided via an intake rocker arm and an exhaust rocker arm that are swingably supported on a pair of rocker arm shafts, respectively. And the pair of rocker arm shafts are located between the first bearing portion and the mating surface in the cylinder axis direction, and define a rotation center line of the cam shaft in plan view. One end of the pair of rocker arm shafts is supported by a pair of support portions formed by the side walls, and the pair of support portions is configured to connect the first bearing portion in plan view. It is located at the sandwiching position.

  According to this, since the pair of support portions supported by the pair of support portions formed by the side walls between the first bearing portion and the mating surface in the cylinder axis direction has no mating surface, the seal is provided. Since there is no need to provide a seal region for ensuring the performance, the amount of protrusion of the pair of support portions toward the spark plug or the plug cap is suppressed, and the inclination of the insertion hole with respect to the cylinder axis in a side view, and thus the spark plug and In addition to making it possible to reduce the inclination of the plug cap, the distance between the two rocker arm shafts can be reduced by bringing both rocker arm shafts close to the cam shaft.

  According to a third aspect of the present invention, in the cylinder head for the internal combustion engine according to the first aspect, the intake valve and the exhaust valve have the valve operating via an intake rocker arm and an exhaust rocker arm having rollers that contact the valve operating cam. Each of which is opened and closed by a cam, the second bearing portion supports the other end of the camshaft, and the valve cam is disposed between the first bearing portion and the second bearing portion; The distance in the axial direction between the second bearing portion and the second bearing portion is substantially equal to the range in the axial direction in which the valve cam is provided.

  According to this, the contact between the valve operating cam and the rocker arm becomes rolling contact and the friction coefficient decreases, so that even if the contact pressure between the valve operating cam and the rocker arm is increased, the resistance of the valve operating cam and the rocker arm is increased. Since the abrasion does not decrease, the width of the valve cam in the axial direction can be reduced. Further, the distance between the first and second bearings that support both ends of the camshaft is reduced according to the range in which the valve cam is provided.

  According to a fourth aspect of the present invention, in the cylinder head of the first aspect, the intake valve is provided on one side wall of the cylinder head in a direction orthogonal to a rotation center line of the cam shaft in a plan view. A mounting hole in which a fuel injection valve facing an intake port having an intake port opened and closed by a cylinder is formed, and a breather passage communicating with a breather chamber formed in the cylinder head cover is formed, and the fuel injection valve is provided in the cylinder. It is located closer to the intake port with respect to the breather chamber in the axial direction, and at a position overlapping the breather passage as viewed in the axial direction.

  According to this, in the cylinder head, the fuel injection valve can be arranged close to the rotation center line of the camshaft in the orthogonal direction without being hindered by the breather passage and the breather chamber having a large volume. The fuel injection valve injects the fuel from the fuel injection valve toward the intake port of the intake port so that the fuel injection center line is more along the cylinder axis direction. So that blow through to the exhaust port is reduced.

  In this specification and claims, the axial direction is the direction of the rotation centerline of the camshaft, the plan view means viewing from the direction of the cylinder axis, and the side view means the cam. This means viewing from a direction perpendicular to a plane that includes the axis of rotation of the shaft and that is parallel to the cylinder axis.

  According to the first aspect of the invention, the following effects can be obtained. That is, since the inclination of the insertion hole can be reduced, the increase in the volume of the combustion chamber due to the insertion hole is suppressed, the engine output is improved, and the retreat of the electrode portion into the insertion hole is suppressed, and the ignitability is improved. Moreover, it is not necessary to increase the thickness of the side wall for increasing the support rigidity of the camshaft, which is necessary when the bearing is divided, and thus the weight of the internal combustion engine can be reduced.

  According to the second aspect of the present invention, the following effect is achieved in addition to the effect of the first aspect of the invention. That is, reducing the inclination of the ignition plug or the plug cap is not hindered by the support portions of the pair of rocker arm shafts, and the both rocker arm shafts are brought closer to the cam shaft to reduce the distance between the shafts. Therefore, the size of the cylinder head can be reduced in a direction perpendicular to the rotation center line in plan view.

  According to the third aspect of the present invention, the following effect is achieved in addition to the effect of the first aspect of the present invention. That is, the width of the valve cam in the axial direction can be reduced, and the interval between the first and second bearings is reduced in accordance with the range in which the valve cam is provided. The size of the cylinder head can be reduced in the axial direction.

  According to the fourth aspect of the present invention, the following effect is achieved in addition to the effect of the first aspect of the present invention. That is, since the fuel injection valve can be arranged close to the rotation center line of the camshaft in the orthogonal direction, the fuel injection valve can be compactly arranged on the cylinder head in the orthogonal direction, and the area around the cylinder head can be arranged. The engine output can be increased because the fuel can be made compact and fuel can be injected from the fuel injection valve such that the injection center line is more in line with the cylinder axis, thereby reducing blow-through to the exhaust port. be able to.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
Referring to FIG. 1, an internal combustion engine E to which the present invention is applied is a single cylinder, four stroke, spark ignition type internal combustion engine mounted on a motorcycle V.

  The scooter type motorcycle V includes a body frame F having a front frame 1 and a rear frame 2, a front fork 3 rotatably supported by a head pipe 1 a of the front frame 1, and a lower end portion of the front fork 3. A front wheel 6 rotatably supported by an arm 4 movably supported; a front cushion 5 connecting the front fork 3 to the arm 4; a handle 7 fixed to an upper end of the front fork 3; F, a swing type power unit P swingably supported by a pivot 8 provided on the rear frame 2, a rear wheel 10 rotatably supported at the rear end of the power unit P, and a rear frame 2 and the power unit P. A rear cushion 9 connecting the rear part, a storage box 12 attached to the rear frame 2 for storing articles such as a helmet 11, and a storage box 12; The vehicle includes a seat 13 attached to an upper portion to cover the opening of the storage box 12 so as to be able to open and close, a fuel tank 14 attached to the front frame 1, and a body cover 15 covering the body frame F.

  The body frame F is a two-part frame in which the front frame 1 and the rear frame 2 are mutually connected by bolts. The front frame 1 includes a head pipe 1a, a down frame 1b extending downward from the head pipe 1a, and a pair of left and right floor support frames 1c extending substantially horizontally rearward from the lower end of the down frame 1b. These are members integrally formed by casting. The rear frame 2 is a member in which a pair of left and right main frames 2a and a plurality of cross members (not shown) connected to the two main frames 2a are integrally formed by casting. The front ends of the left and right main frames 2a are respectively connected to the rear ends of the left and right floor support frames 1c by bolts.

  The vehicle body cover 15 includes a front cover 15a that covers a front portion of the head pipe 1a, a leg shield 15b that covers a rear portion of the head pipe 1a and the down frame 1b, and is located in front of a driver's leg. It includes a step floor 15c to be mounted, an under cover 15d disposed below the step floor 15c to cover the left and right floor support frames 1c, and a rear cover 15e to cover the left and right main frames 2a.

  The fuel tank 14 is disposed between the left and right floor support frames 1c in a storage space formed by the step floor 15c and the under cover 15d. The fuel in the fuel tank 14 is pumped up by a fuel pump and supplied to a carburetor and a fuel injection valve 36 of the internal combustion engine E, which will be described later.

  The power unit P includes a horizontally disposed internal combustion engine E having a crankshaft extending in the left-right direction, and a V-belt type automatic transmission M as a transmission for transmitting the power of the internal combustion engine E to the rear wheels. The internal combustion engine E includes a crankcase connected to a transmission case M1 of the automatic transmission M, and a horizontally arranged cylinder 20 that extends slightly forward from the crankcase inclining slightly upward with respect to the horizontal direction. The crankshaft is housed in a crank chamber formed by the crankcase, and is rotatably supported by the crankcase. Then, the rotation of the crankshaft is steplessly changed by the automatic transmission M according to the engine rotation speed and transmitted to the rear wheel 10, and the rear wheel 10 is rotationally driven by the internal combustion engine E. In addition, above the cylinder head 21 described later, the storage box 12, which is a member on the vehicle body side, is disposed in close proximity, and in front of the cylinder head 21, a step floor 15c is disposed at a relatively small interval. I have. Here, the horizontally arranged cylinder 20 means a cylinder whose cylinder axis L1 is within an angle range of 45 ° or less with respect to the horizontal direction when viewed from the direction of the rotation center line of the crankshaft.

  The internal combustion engine E will be further described with reference to FIGS. Referring first to FIGS. 2 and 3, a SOHC type water-cooled internal combustion engine E includes a cylinder 20 in which a piston 25 is reciprocally fitted, and a cylinder connected to the cylinder 20 by four head bolts B1 to B4. The engine includes a head 21, a cylinder head cover 22 coupled to a mating surface 23 of the cylinder head 21 via a seal member 24, and the crankcase having a skirt portion of the cylinder 20 as a part thereof.

  The piston 25 fitted in the cylinder hole 20a of the cylinder 20 is connected to the crankshaft via a connecting rod 26, and the reciprocating motion of the piston 25 is converted into the rotational motion of the crankshaft.

  Referring also to FIG. 4, the cylinder head 21 has a combustion chamber 27 formed of a concave portion formed on a wall surface facing the cylinder hole 20a in the direction A1 of the cylinder axis L1 and a pair of intake air opening to the combustion chamber 27. An intake port 28 having a port 28a, an exhaust port 29 having a pair of exhaust ports 29a opening into the combustion chamber 27, and an insertion hole 31 into which a spark plug 30 is inserted are formed. And a pair of exhaust valves 33 for respectively opening and closing a pair of intake valves 32 and a pair of exhaust ports 29a.

  An intake pipe 34 of an intake device having a carburetor as a main fuel supply device is connected to an outer surface 21a on the intake side of the cylinder head 21 where an inlet 28b of the intake port 28 opens so as to communicate with the inlet 28b. An exhaust pipe 35 (see FIG. 1) of the exhaust device is connected to the exhaust side outer surface 21b of the cylinder head 21 where the outlet 29b of the port 29 opens. Further, a mounting hole 21c (see FIGS. 2, 6, and 7) formed on the intake side of the cylinder head 21 is used for increasing the amount of fuel for additionally supplying fuel when the internal combustion engine E is started or accelerated. A fuel injection valve 36 as an auxiliary fuel supply device is mounted facing the intake port 28.

  Here, the intake side means a side on which the intake valve 32 is disposed with respect to a plane H1 that includes the rotation center line L2 of the cam shaft 41 and is parallel to the cylinder axis L1, and the exhaust side is a plane with respect to the plane H1. Means the side where the exhaust valve 33 is arranged.

  The air-fuel mixture containing fuel supplied from the carburetor and the fuel injection valve 36 passes through a pair of intake valves 32 opened from the intake port 28 in the combustion chamber 27 during an intake stroke in which the piston 25 descends. Inhaled. The air-fuel mixture sucked into the cylinder 20 is compressed by a piston 25 that rises in a compression stroke, is ignited by a spark plug 30 and burns, and the piston 25 that falls by the pressure of the combustion gas in an expansion stroke is connected to a connecting rod 26. The crankshaft is driven to rotate via the. In the exhaust stroke, the combustion gas passes through a pair of opened exhaust valves 33 and is exhausted as exhaust gas from the combustion chamber 27 to an exhaust port 29, and furthermore, an exhaust pipe 35 and a muffler 37 of the exhaust device (see FIG. 1). Is discharged to the outside.

  Referring to FIGS. 2, 3, and 5, each intake valve 32 and each exhaust valve 33 urged in the valve closing direction by a valve spring 38 include a valve operating chamber formed by the cylinder head 21 and the cylinder head cover 22. It is opened and closed by a valve train 40 arranged in 39. The valve gear 40 includes a single camshaft 41 rotatably supported by a pair of bearings 51 and 53 formed on the cylinder head 21, and a pair of valve cams provided on the camshaft 41. An intake rocker arm 44 and an exhaust rocker arm 45 oscillated by the intake cam 42 and the exhaust cam 43, respectively, and a pair of rocker arm shafts 46, 47 supported by the cylinder head 21 and slidably supporting the two rocker arms 44, 45, respectively. And

  The camshaft 41 is driven to rotate at half the rotation speed thereof by the power of the crankshaft transmitted via a transmission mechanism provided between the camshaft 41 and the crankshaft. The transmission mechanism is wound around a driving sprocket as a driving rotating body provided on the crankshaft, a cam sprocket 48 as a driven rotating body provided on the camshaft 41, and the driving sprocket and the cam sprocket 48. And a timing chain 49 as an endless drive band.

  6 and 7, a pair of bearings 51 and 53 located closer to the cylinder 20 than the mating surface 23 in the cylinder axis direction A1 are provided at one end of the camshaft 41 in the axial direction A2. A first bearing portion 51 supports the first portion 41a via a bearing 50 formed of a ball bearing, and a second bearing portion 53 supports the other end portion 41b in the axial direction A2 via a bearing 52 formed of a ball bearing.

  The first bearing portion 51 located between the insertion hole 31 and the mating surface 23 in the cylinder axial direction A1 forms a part of the one side wall 54 of the cylinder head 21 in the axial direction A2, that is, the side wall 54. It is formed by a part of the intermediate wall 54c between the formed combustion chamber wall 54a in which the insertion hole 31 is formed and the flange 54b having the mating surface 23, and has a shape that covers the entire end face 41a1 of the one end 41a. The first end portion 41a is supported via a bearing 50 fitted into a bottomed concave portion 55 formed on the inner surface of the first bearing portion 51, that is, the wall surface of the side wall 54 on the valve chamber 39 side. The first bearing portion 51 is located at a position overlapping the insertion hole 31 in a plan view (see FIGS. 5 and 7). The outer surface 51a of the first bearing 51 in the axial direction A2 is substantially parallel to a plane orthogonal to the rotation center line L2 (see FIG. 5).

  Further, referring to FIG. 7, the first bearing portion 51 is located at a position overlapping with the spark plug 30 or the plug cap 56 attached to the spark plug 30 when viewed from the axial direction A2. Further, the first bearing portion 51 has a side wall 54 in which a boss 58 formed with an insertion hole 57 through which the intake side head bolt B1 (see FIG. 3) is inserted and an exhaust side head bolt B3 inserted. It is located between the boss portion 60 in which the hole 59 is formed (see also FIG. 7).

  Referring to FIGS. 5, 6, and 8, the second bearing 53 is formed integrally with the cylinder head 21 so as to partition the valve chamber 39 and the transmission chamber 61 from the combustion chamber 27 side to the cylinder head cover 22. The camshaft 41 is formed by a part of a partition wall 62 extending substantially parallel to a plane orthogonal to the rotation center line L2, and a camshaft 41 via a bearing 52 fitted in a through hole 63 formed in the partition wall 62. Supports end 41b. The second bearing portion 53 occupies a position that partially overlaps with the combustion chamber 27 in plan view (see FIG. 5). The second bearing portion 53 includes a partition wall 62, a boss portion 65 having an insertion hole 64 through which an intake side head bolt B2 (see FIG. 3) is inserted, and an exhaust side head bolt B4 (see FIG. 3). ) Is located between the boss 67 and an insertion hole 66 in which the insertion hole 66 is inserted.

  Referring to FIGS. 2, 3, and 5, in the camshaft 41, the intake cam 42 and the exhaust cam 43 are provided between the first bearing 51 and the second bearing 53 in the axial direction A2. The distance between the bearing 51 and the second bearing 53 in the axial direction A2 is substantially equal to the range D (see FIG. 5) in the axial direction A2 in which the intake cam 42 and the exhaust cam 43 are provided on the camshaft 41. Here, the exhaust cam 43 is located at a position crossing the cylinder axis L1. Further, the cam sprocket 48 is coupled to a portion facing the inside of the transmission chamber 61 in which the timing chain 49 is accommodated at the other end 41b on the side opposite to the intake cam 42 with the second bearing 53 therebetween.

  The intake rocker arm 44 has a supported portion 44a formed with a through hole through which the rocker arm shaft 46 is inserted, and a roller 44d extending from the supported portion 44a toward the cam shaft 41 and in rolling contact with the intake cam 42. The roller rocker arm includes a driving section 44b provided and a pair of action sections 44c extending from the supported section 44a toward the pair of intake valves 32 and capable of contacting the intake valves 32.

  The exhaust rocker arm 45 includes a supported portion 45a having a through hole through which the rocker arm shaft 47 is inserted, and a roller 45d extending from the supported portion 45a toward the camshaft 41 and in rolling contact with the exhaust cam 43. Is a roller rocker arm having a driving portion 45b rotatably provided, and a pair of operating portions 45c extending from the supported portion 45a toward the pair of exhaust valves 33 and being able to contact the intake valves 32. is there.

  Here, the rollers 44d, 45d are rotatably supported via a large number of needles 44f, 45f disposed around support shafts 44e, 45e fixed to the driving units 44c, 45c. Each rocker arm 44, 45 is urged by a positioning spring 68 formed of a compression coil spring fitted on each rocker arm shaft 46, 47, and occupies a predetermined position in the axial direction A2.

  Therefore, each intake valve 32 and each exhaust valve 33 are synchronized with the rotation of the crankshaft via an intake rocker arm 44 oscillated by an intake cam 42 and an exhaust rocker arm 45 oscillated by an exhaust cam 43. It is opened and closed by the intake cam 42 and the exhaust cam 43 at a predetermined timing, respectively.

  The two rocker arm shafts 46 and 47 are arranged parallel to the rotation center line L2 of the cam shaft 41, and are arranged on both sides of the rotation center line L2 of the cam shaft 41 and the cam shaft 41 in plan view. Referring to FIGS. 6 to 8 together, one end of each rocker arm shaft 46, 47 is a part of a side wall 54 located between the first bearing portion 51 and the mating surface 23 in the cylinder axial direction A1, that is, an intermediate wall. The other end is supported by a part of a partition wall 62 located between the second bearing 53 and the mating surface 23 in the cylinder axis direction A1. Supported by the second support portions 72 and 73.

Holes 74 to 77 into which the ends of the rocker arm shafts 46 and 47 are fitted are formed in the support portions 71 to 73 located closer to the cylinder 20 than the flange 54b of the mating surface 23 in the cylinder axis direction A1. ing. The pair of first support portions 70 and 71 are located at positions sandwiching the first bearing portion 51 in plan view (see FIGS. 6 and 7).

  Referring to FIGS. 4 to 7, an insertion hole 31 having a female screw portion 31a into which a male screw portion 30a formed at the tip of the ignition plug 30 is screwed is provided with an outer opening portion 31b opening on the outer surface of the combustion chamber wall 54a. And a combustion chamber side opening 31c that opens substantially at the center of the ceiling surface of the combustion chamber 27, which is the inner surface of the combustion chamber wall 54a. The ignition plug 30 is mounted on the combustion chamber wall 54a with the electrode portion 30c protruding from the male screw portion 30a facing substantially the center of the combustion chamber 27 in a state where the external thread portion 30a is not exposed inside the combustion chamber 27. You. Therefore, the center electrode 30c1 and the side electrode 30c2 are located at positions intersecting the cylinder axis L1.

  The insertion hole 31 is formed at a position intersecting the plane H1 (see FIG. 7), and the opening 31c intersects the cylinder axis L1. Further, as shown in FIG. 5, the insertion hole 31 is inclined in a side view to the side opposite to the side where the second bearing portion 53 is located with respect to the cylinder axis L1, and the ignition plug 30 and the plug cap The portion 56a coaxial with the ignition plug 30 of 56 is also inclined at the same angle as the insertion hole 31.

  With the spark plug 30 attached to the cylinder head 21, the spark plug 30 extending from the combustion chamber wall 54a toward the cylinder head cover 22 extends in three directions by the side wall 54, that is, in a direction A3 orthogonal to the plane H1 (in plan view). And the direction perpendicular to the rotation center line L2) are surrounded by the boss portions 58 and 60 which are a part of the side wall 54, and the depth direction in the axial direction A2 is surrounded by the intermediate wall 54c which is a part of the side wall 54. And is housed in a recess 78 formed. In order to connect the high-voltage cord connected to the ignition coil to the ignition plug 30, the plug cap 56 attached to the ignition plug 30 is disposed between the first support portions 70 and 71 in the recess 78. Is done.

  Referring to FIGS. 3 and 5, a cooling water pump as an accessory having a rotation center line that is adjacent to the other end portion 41b of the cam shaft 41 in the axial direction A2 and coincides with the rotation center line L2 of the cam shaft 41. 80 is placed.

  A cooling water pump 80 mounted on the cylinder head 21 has a pump body 81 disposed in the transmission chamber 61 and fixed to the other side wall 79 in the axial direction A2 of the cylinder head 21, and a pump outside the cylinder head 21. A pump cover 82 coupled to the body 81 to form a pump chamber 83 with the pump body 81, a support shaft 84 held by the pump body 81 and the pump cover 82, and a support shaft housed in the pump body 81. And an impeller 85 having a plurality of blades 85b rotatably supported by the pump chamber 83 and supported by the pump chamber 83.

  The cooling water pump 80 is driven by the camshaft 41 via a driving mechanism provided between the cooling water pump 80 and the camshaft 41. The drive mechanism includes a drive rotating body 86 coupled to an end surface 41b1 where the other end portion 41b of the cam shaft 41 faces the transmission chamber 61 by a bolt B5 together with a cam sprocket 48, and a main body portion which is a part of an impeller 85. 85a. The drive rotating body 86 whose part close to the cam shaft 41 is arranged inside the timing chain 49 and is housed in the bowl-shaped cam sprocket 48 has an annular permanent magnet 86c fixed to a part surrounding the periphery of the pump body 81. And the main body 85a of the impeller 85 has an annular permanent magnet 85c fixed at a position radially opposed to the permanent magnet 86c. When the driving rotator 86 rotates together with the cam shaft 41, the impeller 85 magnetically coupled to the driving rotator 86 via the permanent magnets 86c and 85c rotates, and the cooling water flowing into the pump chamber 83 is pumped. Is done.

  The pump cover 82 is provided with a thermostat 90 for controlling the flow of the cooling water in the cylinder 20 and the cylinder head 21 according to the temperature of the cooling water. The thermostat 90 has a valve body 92 driven by a wax 91 that expands and contracts according to the temperature of the cooling water to open and close an inflow passage 93 formed in the pump cover 82.

  When the internal combustion engine E is warmed up, the valve body 92 closes the inflow passage 93 to prevent the cooling water from the radiator (not shown) from flowing into the cooling water pump 80 as shown in FIG. Therefore, the cooling water flowing from the bypass passage 94 is pumped by the cooling water pump 80 and circulates through the cylinder 20 and the cylinder head 21. After the warm-up is completed, the valve element 92 opens the inflow passage 93, so that the cooling water, which has been radiated by the radiator and has become low temperature, flows into the cooling water pump 80 and is pumped, and further the cylinder 20 and the cylinder head 21 are moved. After cooling, it circulates in the path returning to the radiator.

  Referring to FIG. 2, FIG. 3, and FIG. 6, the intake of the cylinder head 21 in which the fuel injection valve 36 is mounted in the mounting hole 21c formed in the upper wall 69 which is one side wall of the cylinder head 21 in the orthogonal direction A3. On the intake side of the cylinder head cover 22, which is also the upper part of the cylinder head cover 22, a breather chamber 100 communicating with the breather passage R communicating with the crank chamber is provided above the valve operating chamber 39 and the transmission chamber 61. It is provided adjacently.

  The breather passage R includes a breather passage 120 formed in the cylinder head 21 and communicating with the breather chamber 100, and a cylinder side formed in the cylinder 20 and communicating with the breather passage 120 at one end and communicating with the crank chamber at the other end. And a breather passage (not shown). A breather passage 120 formed of a through-hole extending in the cylinder axial direction A1 adjacent above the valve operating chamber 39 and the transmission chamber 61 is formed in an upper wall 69 which is also an upper wall of the valve operating chamber 39 and the transmission chamber 61. You. The breather passage 120 has an opening 120a on the side of the breather chamber 100 that opens on the mating surface 23, and an opening 120b on the cylinder 20 side that opens on the mating surface 21h with the cylinder 20 and communicates with one end of the cylinder-side breather passage. (See FIG. 4).

  The fuel injection valve 36 extending along the outer surface 69a in a state close to the outer surface 69a of the upper wall 69 is disposed at a position overlapping the breather chamber 100 in a plan view, and an end 36a connected to the fuel supply pipe. Occupies a position close to the flange 69b of the upper wall 69. Referring to FIGS. 2 and 7, the fuel injection valve 36 is located closer to the intake port 28a or closer to the cylinder 20 with respect to the breather chamber 100 in the cylinder axial direction A1, and also has a breather passage 120 viewed in the axial direction A2. It is in the position which overlaps with.

  Referring to FIGS. 2, 9, 10, and 12, the breather chamber 100 located only on the cylinder head cover 22 side with respect to a plane on the same plane as the mating surface 23 in the cylinder axis direction A1 is located at the uppermost position of the cylinder head cover 22. The first chamber 101 is formed by a concave portion formed in the breather chamber forming portion 103 composed of an upper portion, and the hat-shaped cover 104 is hermetically attached to the breather chamber forming portion 103 so as to cover the first chamber 101. And a second chamber 102.

  The breather chamber forming portion 103 has a flat bottom wall 103a having a head side surface 103b which is flush with the mating surface 22a with the mating surface 23 of the cylinder head cover 22 and forms a part of the mating surface 22a. The opening 120a is covered by the bottom wall 103a. Therefore, a seal groove 103c in which a seal member 24 for sealing the space between the head side surface 103b and the mating surface 23 that defines the upper edge 120a1 of the opening 120a is formed. Further, the bottom wall 103a is formed with a through hole, and an inlet path 105 for communicating the breather passage 120 with the first chamber 101 and an oil return path 106 located below the inlet path 105 are formed. .

  3 and 6, the cylinder head 21 has a partition 107 that partitions the breather passage 120 from the valve operating chamber 39 and the transmission chamber 61 and that has an end face 107 a flush with the mating face 23. It is formed. The partition wall 107 has a projection 107b protruding downward along the partition wall 62 toward the valve operating chamber 39 at a connection portion of the partition wall 62 extending in the vertical direction in plan view with the partition wall 107. A groove 108 communicating with the oil return passage 106 in the breather passage 120 is formed in the protrusion 107b. As shown in FIG. 9, the groove 108 extends below the lower edge 103a1 of the bottom wall 103a so that the lowermost portion thereof is not covered by the bottom wall 103a, and moves at an outlet 110 formed thereby. It communicates with the valve chamber 39 and the transmission chamber 61. Therefore, the communication passage 109 that connects the breather chamber 100 with the valve operating chamber 39 and the transmission chamber 61 is formed by the groove 108.

  On the other hand, the cover 104 is fixed to the cylinder head 21 together with the breather chamber forming portion 103 by three bolts B6 in a state where the cover 104 is sealed via a sealing member 111 on a mating surface 103d formed on the breather chamber forming portion 103. For this reason, a seal groove 104c in which the seal member 111 is mounted is formed in the mating surface 104d of the cover 104 with the mating surface 103d, and a through hole formed in the breather chamber forming portion 103 is formed in the flange of the cover 104. There is formed a through hole 104e that penetrates through 103e and through which each bolt B6 to be screwed into the screw hole 21e formed in the flange 69b of the cylinder head 21.

  Further, the cover 104 is provided with an outlet passage 112 arranged between the breather chamber 100 and the inlet passage 105 with a plurality of projecting walls 103k, 103m; 104k, 104m described later interposed therebetween. The outlet channel 112 is formed here by a pipe fitting 113 pressed into the cover 104. A return pipe (not shown) that forms a return path communicating with the intake path of the intake device is connected to the pipe joint 113, and the breather chamber 100 and the intake path are connected to each other through an outlet path 112 and the return path. Communicate.

  Referring to FIG. 9, FIG. 11, and FIG. 12, the breather chamber forming portion 103 and the cover 104 have mating portions 103k1 which abut each other in order to separate oil from blow-by gas containing oil flowing into the breather chamber 100. , 103m1, 103n1; a plurality of protruding walls 103k, 103m, 103n; 104k, 104m, 104n that have the breather chamber 100 in a maze shape and have 104k1, 104m1, 104n1. Then, the blow-by gas flowing into the breather chamber 100 from the inlet path 105 flows toward the outlet path 112 while colliding with the protruding walls 103k, 103m, 103n; 104k, 104m, 104n in the breather chamber 100. This promotes oil separation.

  Then, the blow-by gas containing the oil for lubrication of the internal combustion engine E passes through the breather passage 120 from the crank chamber, and then flows into the breather chamber 100 mainly from the inlet passage 105. The blow-by gas that has flowed into the breather chamber 100 collides with the protruding walls 103k, 103m, 103n; 104k, 104m, 104n, flows through the breather chamber 100 partitioned in a maze, and oil is separated. The blow-by gas from which oil has been separated is sucked by the negative pressure of the intake passage, flows into the intake passage through the outlet passage 112 and the return passage, and further flows into the combustion chamber 27 for combustion. The separated oil flows from the oil return path 106 into the communication path 109, flows down the communication path 109, flows into the valve operating chamber 39 and the transmission chamber 61, and lubricates the valve operating apparatus 40 and the transmission mechanism. To be served.

Next, the operation and effect of the embodiment configured as described above will be described.
A first bearing portion for supporting one end 41a of a single camshaft 41 in a cylinder head 21 in which an insertion hole 31 into which an ignition plug 30 having an electrode portion 60c facing a substantially central portion of a combustion chamber 27 is inserted is formed. 51 is located at a position overlapping the insertion hole 31 in a plan view, and is located between the insertion hole 31 and the mating surface 23 in the cylinder axis direction A1, and is constituted by the side wall 54 of the cylinder head 21 and has one end 41a. When the ignition plug 30 or the plug cap 56 overlaps the first bearing portion 51 when viewed from the axial direction A2, the first bearing portion 51 does not have the mating surface 23 so that the sealing performance is secured. It is not necessary to provide a sealing region for the first bearing portion 51 when viewed from the axial direction A2, so that the amount of protrusion toward the ignition plug 30 or the plug cap 56 is suppressed, and the cylinder is viewed from the side. Inclination of the insertion hole 31 with respect to the axis L1, As a result, the inclination of the spark plug 30 and the plug cap 56 can be reduced, so that an increase in the volume of the combustion chamber 27 due to the space 31d (see FIG. 5) not occupied by the spark plug 30 in the insertion hole 31 is suppressed, and the engine output is improved. Further, the retreat of the electrode portion 30c into the insertion hole 31 is suppressed, and the ignitability is improved. Further, the first bearing portion 51 does not require an increase in the thickness of the side wall 54 for increasing the support rigidity of the camshaft 41, which is necessary when the bearing portion is divided, so that the weight of the internal combustion engine E can be reduced. Will be possible.

  The intake valve 32 and the exhaust valve 33 are opened and closed by an intake cam 42 and an exhaust cam 43 via an intake rocker arm 44 and an exhaust rocker arm 44, which are swingably supported by a pair of rocker arm shafts 46 and 47, respectively. The rocker arm shafts 46 and 47 are located between the first bearing portion 51 and the mating surface 23 in the cylinder axis direction A1, and are disposed on both sides of the rotation center line L2 of the cam shaft 41 in plan view. One ends of the pair of rocker arm shafts 46, 47 are supported by a pair of first support portions 70, 71 constituted by side walls 54, and both support portions 70, 71 sandwich the first bearing portion 51 in plan view. Since the support portions 70 to 73 do not have the mating surface 23 in the position, there is no need to provide a sealing area for ensuring the sealing performance. Alternatively, the amount of protrusion toward the plug cap 56 is suppressed, Since it becomes possible to reduce the inclination of the insertion hole 31 with respect to the cylinder axis L1 and the inclination of the spark plug 30 and the plug cap 56 visually, it is possible to reduce the inclination of the ignition plug 30 or the plug cap 56 by one. The first rocker arm shafts 46, 47 are not hindered by the first support portions 70, 71, and the two rocker arm shafts 46, 47 can be brought close to the cam shaft 41 to reduce the distance between the cam shafts. The cylinder head 21 can be reduced in size in the direction A3 perpendicular to the rotation center line L2 when viewed.

  The intake rocker arm 44 and the exhaust rocker arm 45 are roller rocker arms having rollers 44d and 45d that contact the intake cam 42 and the exhaust cam 43, respectively. The second bearing 53 supports the other end 41b of the cam shaft 41, The cam 42 and the exhaust cam 43 are disposed between the first bearing portion 51 and the second bearing portion 53, and the distance between the first bearing portion 51 and the second bearing portion 53 in the axial direction A2 is the intake cam 42 and the exhaust cam. Since the contact between the cams 42 and 43 and the rocker arms 44 and 45 becomes rolling contact and the coefficient of friction is reduced by being substantially equal to the range D in the axial direction A2 where the 43 is provided, Even if the contact pressure between 43 and each rocker arm 44, 45 is increased, the abrasion resistance of the intake cam 42, the exhaust cam 43, the intake rocker arm 44, and the exhaust rocker arm 45 does not decrease. 43 small width in the axial direction A2 The distance between the first and second bearings 51 and 53 that support the both ends 41a and 41b of the camshaft 41 is adjusted to the range D where the intake cam 42 and the exhaust cam 43 are provided. Since the size is reduced, the length of the cam shaft 41 can be shortened, and the cylinder head 21 can be reduced in the axial direction A2. Therefore, even when the cooling water pump 80 is arranged adjacent to the other end 41b of the camshaft 41 in the axial direction A2, the internal combustion engine E at the cylinder head 21 of the internal combustion engine E in the axial direction A2 is also used. Increase in size can be suppressed.

  In the upper wall 69 of the cylinder head 21, a mounting hole 21c in which the fuel injection valve 36 is mounted, and a breather passage 120 communicating with a breather chamber 100 formed in the cylinder head cover 22 are formed. In the cylinder axial direction A1, the fuel injection valve 36 is located at a position closer to the intake port 28a of the intake port 28 with respect to the breather chamber 100 and overlaps with the breather passage 120 as viewed in the axial direction A2. Can be disposed close to the rotation center line L2 of the camshaft 41 in the orthogonal direction A3 (or the vertical direction) without being hindered by the breather passage 120 and the breather chamber 100 having a large volume. Since the injection valve 36 can be compactly arranged in the orthogonal direction A3 (or the vertical direction), the area around the cylinder head 21 can be made compact and the axial direction A2 (and (In the direction of the rotation center line of the crankshaft), the inclination of the fuel injection valve 36 with respect to the cylinder axis L1 can be reduced, so that the fuel injection valve can be further aligned with the cylinder axis direction A1. It is possible to inject fuel from the intake port 28a toward the intake port 28a, reduce blow-through to the exhaust port 29, and increase engine output. Since the area around the cylinder head 21 can be made compact, the cylinder head 21 can be arranged in a relatively narrow space formed behind the step floor 15c and below the storage box 12.

  The breather chamber 100 is formed by a breather chamber forming part 103 that is a part of the cylinder head cover 22 and a cover 104 that is attached to the breather chamber forming part 103, so that the breather chamber 100 is reduced in size. Does not restrict the arrangement of the valve operating device 40 in the valve operating chamber 39 formed by the above, and does not increase the volume of the valve operating chamber 39 accompanying the enlargement of the cylinder head 21 and the cylinder head cover 22. Further, the breather chamber 100 is arranged at a position overlapping with the breather chamber 100 in a plan view, and the end 36a avoids interference with the fuel injection valve 36 occupying a position close to the flange 69b, and the large-volume breather chamber 100 is formed. Therefore, the function of separating oil contained in the blow-by gas can be improved, and the breather chamber 100 is not formed in the cylinder head 21, so that the cylinder head 21 can be reduced in size.

Hereinafter, an embodiment in which a part of the configuration of the above-described embodiment is changed will be described with respect to the changed configuration.
Although the internal combustion engine E has a pair of intake valves 32 and a pair of exhaust valves 33, one of the intake valve and the exhaust valve is a pair of valves, and the other is a single valve. Alternatively, both the intake valve and the exhaust valve may be constituted by one valve.

  In the above embodiment, the fuel supply device includes the carburetor and the fuel injection valve 36, but may include only the fuel injection valve mounted on the cylinder head 21 facing the intake port 28. Further, the internal combustion engine E is used for a vehicle in the above embodiment, but may be used for equipment other than the vehicle.

1 is a left side view of a motorcycle equipped with an internal combustion engine including a cylinder head according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a main part of the internal combustion engine of FIG. 1, in which a cylinder head is generally a cross-sectional view taken along a line IIa-IIa in FIG. 3, and a cam shaft and a rocker arm are a cross-sectional view taken along a line IIb-IIb of FIG. . FIG. 3 is a view taken along the line III-III in FIG. 2. FIG. 4 is a view taken in the direction of arrows IV-IV in FIG. 2. FIG. 5 is a sectional view taken along the line VV in FIG. 3. FIG. 2 is a perspective view of a cylinder head of the internal combustion engine of FIG. 1. FIG. 7 is a view of the cylinder head taken along the line VII-VII in FIG. 5. FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 7. FIG. 3 is a view taken along the line IX-IX of a breather chamber forming portion of the cylinder head cover in FIG. 2. FIG. 3 is a XX view of a breather chamber forming portion of the cylinder head cover in FIG. 2. It is sectional drawing in XI-XI arrow of FIG. FIG. 3 is a view taken along arrow XII-XII of a cover forming a breather chamber in FIG. 2.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 ... front frame, 2 ... rear frame, 3 ... front fork, 4 ... arm, 5 ... front cushion, 6 ... front wheel, 7 ... steering wheel, 8 ... pivot, 9 ... rear cushion, 10 ... rear wheel, 11 ... helmet, 12 ... storage box, 13 ... seat, 14 ... fuel tank, 15 ... body cover,
20 ... cylinder, 21 ... cylinder head, 22 ... cylinder head cover, 23 ... mating surface, 24 ... seal member, 25 ... piston, 26 ... connecting rod, 27 ... combustion chamber, 28 ... intake port, 29 ... exhaust port, 30 ... ignition Plug, 30c: Electrode part, 31: Insertion hole, 32: Intake valve, 33: Exhaust valve, 34: Intake pipe, 35: Exhaust pipe, 36: Fuel injection valve, 37: Muffler, 38: Valve spring, 39: Moving Valve chamber, 40: valve gear, 41: cam shaft, 41a: one end, 41b: other end, 42: intake cam, 43: exhaust cam, 44: intake rocker arm, 45: exhaust rocker arm, 46, 47 ... rocker arm Shaft, 48 ... Cam sprocket, 49 ... Timing chain, 50,52 ... Bearing, 51 ... First bearing, 53 ... Second bearing, 54 ... Side wall, 55 ... Recess, 56 ... Plug cap, 57,59 ... Holes, 58, 60: Boss, 61: Transmission chamber, 62: Partition wall, 63: Through hole, 64, 66: Insertion hole, 65, 67: Boss, 68: Positioning bar 69, upper wall, 70, 71 first support portion, 72, 73 second support portion, 74-77 hole, 78 recess, 79 side wall, 80 cooling water pump, 81 pump body, 82 ... pump cover, 83 ... pump chamber, 84 ... support shaft, 85 ... impeller, 86 ... drive rotating body, 90 ... thermostat, 91 ... wax, 92 ... valve body, 93 ... inflow passage, 94 ... bypass passage,
100 ... breather chamber, 101, 102 ... chamber, 103 ... breather chamber forming part, 104 ... cover, 105 ... inlet path, 106 ... oil return path, 107 ... partition wall, 108 ... groove, 109 ... communication path, 110 ... exit, 111: seal member, 112: outlet passage, 113: fitting, 120: breather passage,
V: motorcycle, F: body frame, P: power unit, E: internal combustion engine, M: automatic transmission, B1 to B4: head bolt, B5, B6: bolt, L1: cylinder axis, L2: rotation center line, A1 ... Cylinder axial direction, A2 ... axial direction, A3 ... orthogonal direction, H1 ... plane, D ... range, R ... breather passage.

Claims (4)

A cylinder head of an internal combustion engine coupled to a cylinder, wherein an insertion hole into which a spark plug having an electrode portion facing substantially the center of the combustion chamber is inserted, and a valve cam for opening and closing an intake valve and an exhaust valve are provided. A first bearing portion and a second bearing portion rotatably supporting a single camshaft, and a mating surface to which a cylinder head cover is coupled via a seal member.
The first bearing portion supporting one end of the cam shaft is located at a position overlapping the insertion hole in a plan view, and is located between the insertion hole and the mating surface in a cylinder axis direction, and the cam shaft The ignition plug or the plug cap attached to the ignition plug, when viewed from the axial direction, is formed by the side wall of the cylinder head in the axial direction of An overlapping cylinder head for an internal combustion engine.   The intake valve and the exhaust valve are opened and closed by the valve cam via an intake rocker arm and an exhaust rocker arm swingably supported on a pair of rocker arm shafts, respectively, and the pair of rocker arm shafts are connected to the cylinder axis. In a direction between the first bearing portion and the mating surface, and are disposed on both sides of the rotation center line of the cam shaft in plan view, and one end of the pair of rocker arm shafts is the side wall. The cylinder head according to claim 1, wherein the pair of support portions are supported by a pair of support portions, and the pair of support portions are located at positions sandwiching the first bearing portion in plan view.   The intake valve and the exhaust valve are respectively opened and closed by the valve operating cam via an intake rocker arm and an exhaust rocker arm having rollers that contact the valve operating cam, and the second bearing portion is connected to the other end of the cam shaft. The valve cam is supported between the first bearing portion and the second bearing portion, and a distance between the first bearing portion and the second bearing portion in the axial direction is determined by the valve cam. 2. A cylinder head for an internal combustion engine according to claim 1, wherein said cylinder head is substantially equal to said axial range provided.   On one side wall of the cylinder head in a direction perpendicular to the rotation center line of the cam shaft in plan view, a fuel injection valve facing an intake port having an intake port opened and closed by the intake valve is attached. A hole and a breather passage communicating with a breather chamber formed in the cylinder head cover are formed, and the fuel injection valve is located closer to the intake port with respect to the breather chamber in the cylinder axial direction, and the shaft 2. The cylinder head according to claim 1, wherein the cylinder head is located at a position overlapping the breather passage when viewed from a direction.

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