JP2019120171A - Internal combustion engine - Google Patents

Abstract

To provide an internal combustion engine capable of securing reliable sealing performance and contributing on miniaturization of an auxiliary chamber partition.SOLUTION: An internal combustion engine 24 includes a cylinder head 27 having an auxiliary chamber hole portion 48a at a combustion chamber 41 side, and a plug hole portion 48b having a diameter larger than the auxiliary chamber hole portion 48a and connected with the auxiliary chamber hole portion 48a by a step 56 to form an insertion hole 48 opened at a wall surface of the combustion chamber 41, an auxiliary chamber partition 58 inserted to the auxiliary chamber hole portion 48a to form an auxiliary chamber 46 communicated to the combustion chamber 41, and having a flange 57 overlapped on the step 56, a first seal member 59 overlapped on the flange 57, an ignition plug holder 61 inserted to the plug hole portion 48b, pressing the first seal member 59 toward the flange 57 at a tip, and positioning the tip of the ignition plug 47 with respect to the auxiliary chamber 46, and a second seal member 64 held between the ignition plug holder 61 and an inner wall of the plug hole portion 48b.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a sub-chamber type internal combustion engine in which a sub chamber leading to a combustion chamber is formed in front of a spark plug.

  Patent Document 1 discloses a sub-chamber internal combustion engine in which a sub-chamber leading to a combustion chamber is formed in front of a spark plug. The cylinder head is formed with an insertion hole for receiving the sub-chamber partition wall forming the sub-chamber. The insertion hole has a small diameter portion on the combustion chamber side, and a large diameter portion larger in diameter than the small diameter portion and connected to the small diameter portion by a step. The sub-chamber partition wall has a small diameter cylindrical portion inserted into the small diameter portion of the insertion hole, and a large diameter cylindrical portion connected to the small diameter cylindrical portion and inserted into the large diameter portion of the insertion hole.

JP, 2013-133717, A

  A gasket is attached to the front end of the large diameter cylindrical portion around the small diameter cylindrical portion, and the gasket is sandwiched between the cylinder head and the auxiliary chamber partition by the action of axial pressing force acting on the large diameter cylindrical portion from the ignition plug holder . Since the pressing force of the spark plug holder acts on the large diameter cylindrical portion of the sub chamber partition wall in the axial direction when sandwiching the gasket, a sufficient wall thickness is required of the large diameter cylindrical portion of the sub chamber partition. If the wall thickness of the peripheral wall portion is reduced to miniaturize the sub-chamber partition wall, sufficient sealing performance can not be ensured.

  The present invention has been made in view of the above situation, and has an object to provide an internal combustion engine that can ensure reliable sealing performance and can contribute to downsizing of the sub-chamber partition.

  According to the first aspect of the present invention, it has a sub-chamber hole on the combustion chamber side, and a plug hole having a diameter larger than that of the sub-chamber hole and connected to the sub-chamber hole by a step. A cylinder head forming an insertion hole opened at a wall surface of the combustion chamber, and a sub-chamber partition wall having a flange which is inserted into the sub-chamber hole portion to form a sub-chamber communicating with the combustion chamber and which overlaps the step A first seal member overlapping on the flange, and the first seal member inserted into the plug hole portion and pressing the first seal member toward the flange with its tip to hold the spark plug and the tip of the spark plug in the sub-chamber An internal combustion engine is provided, comprising: a spark plug holder positioned relative to the spark plug holder; and a second seal member interposed between the spark plug holder and the inner wall of the plug hole.

  According to the second side surface, in addition to the configuration of the first side surface, the first seal member is an axial metal seal, and the second seal member is a radial resin seal.

  According to the third aspect, in addition to the configuration of the second side, the sub-chamber hole portion and the sub-chamber partition portion mutually contact each other, and the diameter-reduced portion which radially shrinks toward the combustion chamber Have.

  According to a fourth aspect, in addition to the configuration of the third side, the spark plug holder is formed in a cylindrical shape coaxially with the spark plug, and the first seal is formed between the spark plug holder and the flange of the sub chamber partition wall at the tip. A cylindrical portion sandwiching a member, and a screw portion connected to the upper end of the cylindrical portion and formed in a cylindrical shape coaxially with the spark plug and having a screw groove on the outer periphery, the second portion on the outer periphery of the cylindrical portion The seal member is mounted.

  According to the fifth aspect, in addition to the configuration of the fourth side, the thread groove of the spark plug holder is disposed at a position axially overlapping the thread groove of the spark plug.

  According to a sixth aspect, in addition to the configuration of the fifth side, the internal combustion engine is attached to the cylinder head independently of the spark plug holder, and the ignition is directed toward an opening formed in the sub chamber partition wall. The fuel injection valve is disposed in a posture inclined to the central axis of the plug.

  According to a seventh aspect, in addition to the configuration of the sixth side, the spark plug holder is formed of a copper-based material.

  According to the first aspect, since the first seal member is axially sandwiched between the spark plug holder and the flange of the auxiliary chamber partition by the action of the pressing force acting in the axial direction from the spark plug holder, the pressure of the auxiliary chamber Leaks can be reliably prevented. In addition, since the flange pressed against the step functions as a seal member, even if the peripheral wall in contact with the inner wall of the sub-chamber hole is thin, pressure leakage from the combustion chamber along the inner wall of the sub-chamber hole is reliably prevented. be able to. Furthermore, since the second seal member is disposed outward in the axial direction with respect to the flange of the sub chamber partition wall and the first seal member, a common sealing function is provided for gas leaks in the combustion chamber and gas leaks in the sub chamber. It can be demonstrated. The seal member can be eliminated from the internal combustion engine.

  According to the second aspect, since the first seal member is a metal seal, the first seal member is reliably held even if it is interposed between the flange of the sub chamber partition and the spark plug holder and is subjected to an axial load. Pressure leakage can be prevented. On the other hand, since the second seal member is a seal made of resin, the second seal member is easy to attach and detach, and the maintainability is improved.

  According to the third aspect, by forming the labyrinth structure between the inner wall of the sub chamber hole and the outer surface of the sub chamber partition, pressure leakage from the combustion chamber along the inner wall of the sub chamber hole is prevented. be able to. As a result, the load on the second seal member can be reduced, and the seal structure can be simplified.

  According to the fourth aspect, since the spark plug holder is formed in a cylindrical shape coaxial with the spark plug, it is possible to reduce the difference in external dimensions between the auxiliary chamber and the spark plug holder, and as a result, the intake valve and the exhaust valve The spacing does not need to be extended, and the sub-chamber can be easily applied to a cylinder having a small diameter bore.

  According to a fifth aspect, the igniter plug is coupled to the igniter plug holder by a thread groove, and good heat transfer is realized from the igniter plug to the igniter plug holder in the region of the thread groove. Likewise, the spark plug holder is connected to the cylinder head by means of a thread groove, so that good heat transfer from the spark plug holder to the cylinder head is achieved in the region of the thread groove. Thus, heat transfer from the spark plug to the cylinder head is enhanced.

  According to the sixth aspect, the spark plug holder is disposed axially above the sub chamber partition wall, while the fuel injection valve is disposed around the sub chamber partition wall, so that the spark plug holder and the fuel injection valve The width (diameter) of the sub-chambers can be reduced as compared with the case where the two chambers are arranged side by side. Accordingly, the distance between the intake valve and the exhaust valve arranged around the spark plug and the fuel injection valve does not have to be increased, and the sub chamber can be easily applied to a cylinder having a small diameter bore.

  According to the seventh aspect, since the spark plug holder is formed of a copper-based material, good heat transfer is realized, and the charging of the spark plug is favorably performed according to the good conductivity of the copper-based material. It can be prevented.

FIG. 1 is a side view schematically showing a structure of a motorcycle according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. FIG. 2 is an enlarged plan view in the vicinity of a fuel tank of a motorcycle. It is a principal part enlarged side view of FIG. FIG. 5 is an enlarged cross-sectional view taken along line 5-5 of FIG. 4; It is a principal part expanded sectional view of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the attached drawings. Here, the upper, lower, front, rear, left, and right of the vehicle body are defined based on the line of sight of the passenger on the motorcycle.

  FIG. 1 schematically shows the entire configuration of a motorcycle (one specific example of a saddle-ride type vehicle) according to an embodiment of the present invention. The body frame 12 of the motorcycle 11 is separately coupled to the head pipe 13, a pair of left and right main frames 14 extending backward and backward from the head pipe 13, and the rear ends of the individual main frames 14. And a pair of left and right pivot frames 15 interconnected downward by a cross pipe (not shown), and a down frame 16 extending downward from the head pipe 13 below the main frame 14 . The down frame 16 is branched from the lower end of the upper frame 16a to the left and right from one head frame 16a extending downward from the head pipe 13 at the left and right center position in the vehicle width direction and individually connected to the lower end of the corresponding pivot frame 15. And a pair of lower pipe frames 16b. The upper frame 16 a of the down frame 16 moves downward from the main frame 14 as moving backward from the head pipe 13.

  A front fork 18 rotatably supporting a front wheel WF rotatably around an axle 17 is steerably supported by the head pipe 13. A handle bar 19 is coupled to the front fork 18 on the upper side of the head pipe 13. A swing arm 22 supporting the rear wheel WR rotatably around the axle 21 is pivotably supported around the pivot 23 on the pivot frame 15. The support shaft 23 extends horizontally in the vehicle width direction.

  The internal combustion engine 24 is mounted on the vehicle body frame 12 between the front wheel WF and the rear wheel WR. The internal combustion engine 24 is disposed between the left and right pivot frames 15 and in a space sandwiched by the left and right lower pipe frames 16b and is connected to the pivot frame 15 and the lower pipe frame 16b. A cylinder block 26 having a cylinder axis C which is connected and extends upward from the crankcase 25 and is inclined forward, a cylinder head 27 connected to the cylinder block 26, and a head cover 28 connected to the cylinder head 27. . The crankcase 25 supports a crankshaft that rotates around a rotation axis S extending parallel to the axle 21 of the rear wheel WR. The rotational movement of the crankshaft is transmitted to the rear wheel WR through a transmission (not shown). Here, the internal combustion engine 24 is configured, for example, as a single-cylinder internal combustion engine. The cylinder block 26, the cylinder head 27 and the head cover 28 are between the main frame 14 and the down frame 16 in a side view projected in parallel to the rotational axis S of the crankshaft on a projection plane orthogonal to the rotational axis S of the crankshaft. Will be placed. The detailed description of the structure common to a general internal combustion engine may be omitted hereinafter.

  A fuel injection valve 29 disposed in a space between the main frame 14 and the down frame 16 on one side of the cylinder head 27 and injecting fuel toward the combustion chamber as described later, the main frame 14 and the down A fuel pump 31 is provided which is disposed in the space between the frames 16 and supplies fuel to the fuel injection valve 29 in accordance with the generated pump pressure, as described later. The fuel injection valve 29 is connected to a fuel pipe 32 extending from the discharge pipe 31 a of the fuel pump 31 to connect the fuel injection valve 29 and the fuel pump 31 and introducing fuel from the fuel pump 31 to the fuel injection valve 29.

  A pair of left and right radiators 33 connected to the internal combustion engine 24 and contributing to the cooling of the internal combustion engine 24 are attached to the upper frame 16 a of the down frame 16. The radiator 33 on the left side is disposed forward of the fuel injection valve 29 in the vehicle body. Cooling water circulates between the left and right radiators 33 and the internal combustion engine 24. The coolant heated by the internal combustion engine 24 flows into the radiator 33 and is cooled by the radiator 33. The cooling water cooled by the radiator 33 flows into the cooling jacket of the internal combustion engine 24. As shown in FIG. 2, the fuel pump 31 is disposed inside a virtual plane PP in contact with the outer surface of the main frame 14 and the outer surface of the case cover 25a. The projection of the fuel pump 31 is avoided from an imaginary plane PP in contact with the main frame 14 and the case cover 25a from the left outside. The fuel pump 31 can be protected from collisions with other things.

  As shown in FIG. 1, a fuel tank 34 is supported on the main frame 14 above the internal combustion engine 24. In the fuel tank 34, a primary fuel pump 35 for discharging the fuel from the fuel tank 34 is disposed. The primary fuel pump 35 and the fuel pump 31 are connected to the suction pipe 31b of the fuel pump 31 to connect the primary fuel pump 35, and fuel is supplied from the primary fuel pump 35 to the fuel pump 31 based on the pump pressure of the primary fuel pump 35. The primary fuel pipe 36 is connected. An occupant's seat 37 is mounted on the vehicle body frame 12 behind the fuel tank 34. In driving the motorcycle 11, the occupant straddles the occupant seat 37. As shown in FIG. 3, the fuel pump 31 is hidden behind the fuel tank 34 in a plan view based on a viewpoint located at an upper infinity point. In other words, the fuel pump 31 is disposed inside the curved vertical plane VP parallel to the gravity direction and in contact with the curved outer edge of the fuel tank 34. Thus, the projection of the fuel pump 31 is avoided from the outer shape of the fuel tank 34. The fuel pump 31 can be protected from collisions with other things.

  As shown in FIG. 4, the cylinder block 26 guides the linear reciprocating motion of the piston 38 along the cylinder axis C. Connected to the piston 38 is a connecting rod 39 connected to the crank of the crankshaft in the crankcase 25. The connecting rod 39 converts the linear reciprocating motion of the piston 38 into rotational motion of the crankshaft.

  The cylinder head 27 forms a combustion chamber 41 with the piston 38. In the combustion chamber 41, a pair of intake valves (not shown) individually controlling the opening and closing of the intake port and a pair of exhaust valves (not illustrated) individually controlling the opening and closing of the exhaust port are disposed. Connected to the intake valve is an intake camshaft 42a located rearward of the cylinder axis C in a side view and having an axis parallel to the rotational axis S of the crankshaft. In other words, the intake camshaft 42a is disposed rearward of the virtual plane parallel to the rotation axis S of the crankshaft and including the cylinder axis C. Connected to the exhaust valve is an exhaust camshaft 42b located in front of the cylinder axis C in a side view and having an axis parallel to the rotational axis S of the crankshaft. In other words, the exhaust camshaft 42b is disposed forward of the virtual plane parallel to the rotational axis S of the crankshaft and including the cylinder axis C. As described later, a valve train 43 for transmitting power from the crankshaft to the intake camshaft 42a and the exhaust camshaft 42b is connected to the intake camshaft 42a and the exhaust camshaft 42b. The valve system 43 includes a sprocket 44a fixed to the intake camshaft 42a and a cam chain 45 wound around the sprocket 44b fixed to the exhaust camshaft 42b.

  The central axis of the fuel injection valve 29 (a straight line including the central axis and extending infinitely) is disposed on the cylinder axis C in a side view of the vehicle and passes the head pipe 13 in a side view of the vehicle. In other words, the central axis of the fuel injection valve 29 is disposed in an imaginary plane parallel to the rotational axis S of the crankshaft and including the cylinder axis C, and parallel to the rotational axis S of the crankshaft. A virtual plane including the central axis of the crosses the head pipe 13. The fuel pump 31 is disposed at a position offset rearward from the cylinder axis C in a side view, and the fuel pipe 32 is disposed between the main frame 14 and the down frame 16 in a side view. In other words, the fuel pump 31 is disposed parallel to the rotational axis S of the crankshaft and disposed rearward of the virtual plane including the cylinder axis C, and the fuel pipe 32 is parallel to the rotational axis S of the crankshaft. It is disposed in a space sandwiched by an imaginary plane in contact with the main frame 14 from the front of the vehicle body and an imaginary plane parallel to the rotation axis S of the crankshaft and in contact with the down frame 16 from the rear of the vehicle body. The fuel pipe 32 extends so as to surround the drive shaft (= the intake camshaft 42 a) of the fuel pump 31 around its axis, and is connected to the fuel injection valve 29. The protrusion of the fuel pipe 32 is suppressed outward.

  As shown in FIG. 5, the cylinder head 27 is provided with a sub chamber 46 communicating with the combustion chamber 41 at the top position of the combustion chamber 41 and facing the injection port of the fuel injection valve 29. The cylinder head 27 receives the first spark plug 47, and the insertion hole 48 for arranging the central axis of the first spark plug 47 on the cylinder axis C; and the fuel injection valve 29; At the second inclination angle β which is larger than the first inclination angle α from the cylinder axis C, the insertion hole 49 for arranging the central axis of the fuel injection valve 29 on the axis falling down at the inclination angle α and the second spark plug 51 A screw-in hole 52 for arranging the central axis of the second spark plug 51 is formed on the falling axis. The electrode of the first spark plug 47 faces the space in the auxiliary chamber 46. The electrode of the second spark plug 51 faces the space in the combustion chamber 41. The fuel injection valve 29 is held in an inclined position with respect to the central axis of the first spark plug 47, causes the injection port to face the sub chamber 46, and injects fuel in the sub chamber 46 toward the combustion chamber 41. Here, a gap can be secured between the upper end of the fuel injection valve 29 and the fuel pump 31 by laying the fuel injection valve 29 on the injection passage 49a.

  The intake camshaft 42 a has a rotational axis X extending parallel to the rotational axis S of the crankshaft from one side to the other side of the cylinder head 27. The fuel pump 31 is disposed on an extension of the intake camshaft 42a on one side surface of the cylinder head 27 and connected to the intake camshaft 42a. The sprocket 44 a of the valve system 43 and the cam chain 45 are disposed on the other side of the cylinder head 27. The fuel pump 31 is coaxial with the on-off valves disposed in the suction pipe 31b and the discharge pipe 31a, the plunger 54 for changing the volume of the pressure chamber 53 communicating with the suction pipe 31b and the discharge pipe 31a, and the intake camshaft 42a. And a cam member 55 for producing the reciprocating movement of the plunger 54, and is constituted by a reciprocating fuel pump which discharges high-pressure fuel by receiving a driving force from an intake camshaft 42a.

  As shown in FIG. 6, the insertion hole 48 has a diameter larger than that of the sub-chamber hole (vertical hole) 48 a on the combustion chamber 41 side opened in the wall surface of the combustion chamber 41 and the sub-chamber hole 48 a It has a plug hole 48 b connected to the sub-chamber hole 48 a by an annular step 56. A sub chamber partition 58 communicating with the combustion chamber 41 is formed in the sub chamber hole portion 48 a, and a sub chamber partition 58 having a flange 57 overlapping the step 56 is inserted. Sub-chamber partition 58 is formed of, for example, stainless steel. An annular first seal member 59 overlaps the flange 57. The first seal member 59 is an axial metal seal.

  A spark plug holder for pressing the first seal member 59 at the tip toward the flange 57 to the plug hole 48b and positioning the tip of the first spark plug 47 with respect to the sub chamber 46 while holding the first spark plug 47 61 is inserted. Since the insertion hole 48 and the insertion hole 49 are separately formed in the cylinder head 27, the fuel injection valve 29 is attached to the cylinder head 27 independently of the spark plug holder 61.

  The spark plug holder 61 is formed in a cylindrical shape coaxially with the first spark plug 47, and has a cylindrical portion 61a sandwiching the first seal member 59 with the flange 57 of the sub chamber partition 58 at the tip, and the upper end of the cylindrical portion 61a. The first spark plug 47 is coaxially formed in a cylindrical shape, and has a screw portion 61 b having a screw groove on the outer periphery. The spark plug holder 61 is formed of a copper-based material. The first seal member 59 is sandwiched between the sub chamber partition 58 and the spark plug holder 61 to block the space of the sub chamber 46 from the outside air. The first spark plug 47 is screwed into the spark plug holder 61. The thread groove 62 of the spark plug holder 61 is disposed at a position overlapping the thread groove 63 of the first spark plug 47 in the axial direction.

  An annular second seal member 64 sandwiched between the spark plug holder 61 and the inner wall of the plug hole 48b is mounted on the outer periphery of the cylindrical portion 61a. The second seal member 64 is a radial resin seal. The second seal member 64 mutually shuts off the space in the insertion hole 48 on the combustion chamber 41 side and the space in the insertion hole 48 on the outside air side.

  The sub chamber partition 58 is inserted into the sub chamber hole 48a extending from the combustion chamber 41 along the cylinder axis (reference axis) C, and a peripheral wall 58a contacting the inner wall of the sub chamber hole 48a around the cylinder axis C; It has a bottom wall 58b extending from the sub chamber hole 48a toward the combustion chamber 41 continuously from the peripheral wall 58a, and the sub chamber 46 communicating with the combustion chamber 41 by the peripheral wall 58a and the bottom wall 58b. Form The first spark plug 47 is disposed above the peripheral wall 58a. The bottom wall 58 b bulges towards the combustion chamber 41 in a dome shape. Therefore, the thickness of the bottom wall 58b increases toward the center (the cylinder axis C).

  The peripheral wall portion 58a of the sub chamber partition 58 extends in the radial direction as it approaches the combustion chamber 41 continuously from the lower end of the first cylindrical portion 65a of the first outer diameter D1 supporting the flange 57 at the upper end and the lower end of the first cylindrical portion 65a. And a second cylindrical portion 65c having a second outer diameter D2 smaller than the first outer diameter D1 continuously from the lower end of the reduced diameter portion 65b. The sub chamber hole portion 48 a has a reduced diameter portion 66 which is reduced in the radial direction toward the combustion chamber 41 corresponding to the reduced diameter portion 65 b of the sub chamber partition 58. The reduced diameter portion 65b of the sub chamber partition wall 58 and the reduced diameter portion 66 of the sub chamber hole portion 48a contact each other to form a labyrinth structure. The first cylindrical portion 65a, the reduced diameter portion 65b and the second cylindrical portion 65c are in contact with the inner wall of the sub-chamber hole 48a.

  In the second cylindrical portion 65c, the wall thickness of the peripheral wall 58a increases toward the bottom wall 58b. Here, the second cylindrical portion 65c forms a Taber-shaped space that tapers toward the bottom wall 58b. A communication hole 67 is formed in the peripheral wall 58a at the lower end of the peripheral wall 58a, penetrating the peripheral wall 58a in the thickness direction of the wall, and connecting the auxiliary chamber 46 to the combustion chamber 41. The communication hole 67 radially extends from the cylinder axis C. Positioning protrusions 68 are formed on the outer periphery of the sub-chamber partition 58 continuously from the flange 57 and projecting radially outward at specific positions in the circumferential direction. The sub-chamber hole 48 a is formed with a recess 69 which is recessed from the step 56 at a specific position in the circumferential direction and receives the positioning protrusion 68. By the positioning protrusion 68 being fitted in the recess 69, the angular position of the sub chamber partition 58 can be positioned around the cylinder axis C.

  The cylinder block 27 is formed with a fuel injection passage 71 having a diameter smaller than that of the fuel injection valve 29 and extending from the front end of the insertion hole 49. The axis of the fuel injection passage 71 intersects the cylinder axis C at an inclination angle smaller than the first inclination angle α of the axis Q of the fuel injection valve 29. Thus, the fuel injection valve 29 is inclined with respect to the fuel injection passage 71, whereby a gap can be secured between the upper end of the fuel injection valve 29 and the fuel pump 31, as shown in FIG. The peripheral wall portion 58 a has a passage 72 opened to the inner surface of the peripheral wall portion 58 a closer to the combustion chamber 41 than the reduced diameter portion 65 b as an extension of the fuel injection passage 71. The fuel injection passage 71 leads from the injection port of the fuel injection valve 29 to the opening of the passage 72. The fuel injection valve 29 injects fuel toward the bottom wall 58 b in the sub chamber 46. The fuel injection area is formed to be out of the communication hole 56.

  Next, the operation of the present embodiment will be described. In the present embodiment, the fuel injection valve 29 is attached to the cylinder head 27 from one side of the cylinder head 27. The fuel pump 31 is disposed in the space between the main frame 14 and the down frame 16 and attached to one side of the cylinder head 27. Since the fuel pump 31 is attached to one side of the cylinder head 27 together with the fuel injection valve 29, the interference between the fuel pump 31 and the main frame 14 is avoided relatively without restricting the attitude of the internal combustion engine 24. The fuel pump 31 is disposed between the main frame 14 and the down frame 16 without relatively restricting the attitude of the internal combustion engine. The protection of the fuel pump 31 is sufficiently realized without restricting the attitude of the internal combustion engine 24. Moreover, since the fuel pump 31 and the fuel injection valve 29 are disposed close to each other, the fuel pipe 32 for supplying the fuel from the fuel pump 31 to the fuel injection valve 29 can be shortened as much as possible.

  The central axis of the fuel injection valve 29 passes through the head pipe 13 in a side view projected parallel to the rotational axis S of the crankshaft on a projection plane orthogonal to the rotational axis S of the crankshaft. Since the main frame 14 and the down frame 16 approach each other as they go to the head pipe 13, when the central axis of the fuel injection valve 29 passes the head pipe 13 in a side view, the fuel between the main frame 14 and the down frame 16 Space is secured on the central axis of the injection valve 29. Therefore, the maintainability of the internal combustion engine 24 including the fuel injection valve 29 is improved.

  The central axis of the fuel injection valve 29 is disposed on the cylinder axis C in a side view projected in parallel with the rotational axis S of the crankshaft on a projection plane orthogonal to the rotational axis S of the crankshaft. The fuel pipe 32 is disposed at a position offset from the cylinder axis C in a side view, and is disposed between the main frame 14 and the down frame 16 in a side view. As described above, since sufficient space is secured between the main frame 14 and the down frame 16 on the central axis of the fuel injection valve 29, sufficient space between the main frame 14 and the down frame 16 and the fuel pump 31 is provided. Space is formed. Therefore, the maintainability of the fuel pump 31 is well secured. The fuel piping 32 is well protected between the main frame 14 and the down frame 16.

  The fuel pump 31 is connected to the fuel tank 34 supported by the main frame 14 by the primary fuel pipe 36, and is a side view projected parallel to the rotational axis S of the crankshaft on a projection plane orthogonal to the rotational axis S of the crankshaft. At a position offset rearward from the cylinder axis C. Since the fuel pump 31 is disposed at a position shifted rearward from the cylinder axis C in a side view, the primary fuel pipe 36 connecting the fuel pump 31 to the primary fuel pump 35 in the fuel tank 34 is shortened as much as possible Ru.

  The motorcycle 11 includes a radiator 33 attached to the down frame 16 forward of the fuel injection valve 29 on the vehicle body. The radiator 33 is separated from the fuel pump 31 in front of the fuel pump 31. The fuel pump 31 does not get caught in the warm air of the radiator 33 as much as possible. Thus, the temperature rise of the fuel pump 31 is suppressed.

  The fuel pump 31 is a reciprocating fuel pump disposed on an extension of the intake camshaft 42a supported by the cylinder head 27 and receiving a driving force from the camshaft 42a. The reciprocating fuel pump 31 realizes high-pressure fuel supply according to the driving force of the camshaft 42a rotating at high speed. Therefore, combustion chamber injection of fuel (so-called direct injection) is realized.

  The cylinder head 27 is provided with a sub chamber 46 which communicates with the combustion chamber 41 at the top position of the combustion chamber 41 and in which the injection port of the fuel injection valve 29 faces. Since the combustion chamber 41 approaches the camshafts 42a and 42b most at the top position, the fuel injection valve 29 is disposed as close as possible to the intake camshaft 42a. Thus, the distance between the fuel injection valve 29 and the fuel pump 31 is shortened as much as possible. The fuel pipe 32 connecting the fuel pump 31 to the fuel injection valve 29 is shortened as much as possible, and the space for protecting the fuel injection valve 29 and the fuel pump 31 is reduced.

  The internal combustion engine 24 of the motorcycle 11 has a central axis disposed on the cylinder axis C, and intersects the cylinder axis C at a second inclination angle β with the first spark plug 47 facing the space in the sub chamber 46 A second spark plug 51 having a central axis and facing a space in the combustion chamber 41 is provided. The first spark plug 47 and the second spark plug 51 can be inserted into the cylinder head 27 without interfering with the fuel injection valve 29 and the fuel pump 31 in realizing combustion chamber injection.

  In the internal combustion engine 24 according to the present embodiment, the camshafts 42a and 42b extend from one side to the other side of the cylinder head 26 and on the other side of the cylinder head 27 from the crankshaft to the camshafts 42a and 42b. A valve system 43 for transmitting The fuel pump 31 is disposed on one end side of the camshafts 42a and 42b, and the valve system 43 is disposed on the other end side of the camshafts 42a and 42b, so that the weight balance of the internal combustion engine 24 is well maintained. In addition, the maintainability of the valve system 43 can be favorably maintained without being disturbed by the fuel injection valve 29 and the fuel pump 31.

  In the present embodiment, the first seal member 59 overlaps the flange 57 of the sub chamber partition 58, and the spark plug holder 61 is inserted into the plug hole 48b of the insertion hole 48 and The second seal member 64 is sandwiched between the spark plug holder 61 and the inner wall of the plug hole portion 48 b by pressing the member 59. Since the first seal member 59 is axially sandwiched between the spark plug holder 61 and the flange 57 of the sub chamber partition 58 by the action of the pressing force acting in the axial direction from the spark plug holder 61, pressure leakage of the sub chamber 46 Is reliably prevented. Moreover, since the flange 57 pressed against the step 56 functions as a seal member, even if the peripheral wall 58a of the sub chamber partition 58 in contact with the inner wall of the sub chamber hole 48a is thin, the axial pressing force of the peripheral wall 58 a No deformation is caused, and pressure leakage from the combustion chamber 41 to the inner wall of the sub chamber hole portion 48a is reliably prevented. Further, since the second seal member 64 is disposed axially outward of the flange 57 of the sub chamber partition 58 and the first seal member 59, gas leakage in the combustion chamber 41 and gas leakage in the sub chamber 46 Exhibits the sealing function in common. In the internal combustion engine 24, the seal structure is simplified.

  The first seal member 59 sandwiched between the sub chamber partition 58 and the spark plug holder 61 around the cylinder axis C around the entire circumference is an axial metal seal, and around the cylinder axis C around the entire circumference of the spark plug holder 61. The second seal member 64 sandwiched by the cylindrical portion 61 a and the inner wall of the insertion hole 48 is a resin seal in the radial direction. Since the first seal member 59 is a metal seal, even if the first seal member 59 is pinched between the flange 57 of the sub chamber partition 58 and the spark plug holder 61 and exposed to an axial load, the first seal member 59 reliably leaks pressure. To prevent. On the other hand, since the second seal member 64 is a seal made of resin, the second seal member 64 is easy to attach and detach, and the maintainability is improved.

  In the internal combustion engine 24 according to the present embodiment, the sub-chamber hole portion 48a of the insertion hole 48 and the sub-chamber partition wall 58 contact each other, and the diameter reducing portions 65b and 66 decrease in diameter as they approach the combustion chamber 41. Each has The formation of the labyrinth structure between the inner wall of the sub chamber hole 48 a and the outer surface of the sub chamber partition 58 prevents pressure leakage from the combustion chamber 41 along the inner wall of the sub chamber hole 48 a. As a result, the load on the second seal member 64 is reduced, and the seal structure is simplified.

  The spark plug holder 61 according to the present embodiment is formed in a cylindrical shape coaxially with the first spark plug 47, and has a cylindrical portion 61a sandwiching the first seal member 59 with the flange 57 of the sub chamber partition 58 at its tip; The second seal member 64 is connected to the upper end of the cylindrical portion 61a and formed in a cylindrical shape coaxially with the first spark plug 47, and has a screw portion 61b having a screw groove 62 on the outer periphery. It is attached. Since the spark plug holder 61 is formed in a cylindrical shape coaxial with the first spark plug 47, the difference in external shape between the sub chamber 46 and the spark plug holder 61 can be reduced. As a result, the distance between the intake valve and the exhaust valve It is not necessary to expand, and the sub-chamber can be easily applied to a cylinder having a small diameter bore.

  In the internal combustion engine 24 according to the present embodiment, the screw groove 62 of the spark plug holder 61 is disposed at a position overlapping the screw groove 63 of the first spark plug 47 in the axial direction. The first spark plug 47 is connected to the spark plug holder 61 by means of the thread groove 63 and good heat transfer from the first spark plug 47 to the spark plug holder 61 in the region of the thread groove 63 is realized. Similarly, the spark plug holder 61 is connected to the cylinder head 27 by means of the thread groove 62 and good heat transfer from the spark plug holder 61 to the cylinder head 27 in the area of the thread groove 62 is realized. Thus, the heat transfer from the first spark plug 47 to the cylinder head 27 is promoted.

  As described above, the fuel injection valve 29 is attached to the cylinder head 27 independently of the spark plug holder 61, and the central axis of the first spark plug 47 is directed toward the opening of the passage 72 formed in the sub chamber partition 58. It is arranged in the posture to incline. The spark plug holder 61 is disposed axially above the sub chamber partition 58, while the fuel injection valve 29 is disposed around the sub chamber partition 58. Therefore, the spark plug holder 61 and the fuel injection valve 29 The width (diameter) of the sub chamber 46 is reduced as compared to the case where they are arranged side by side. Therefore, the distance between the intake and exhaust valves disposed around the first spark plug 47 and the fuel injection valve 29 does not have to be increased, and the sub chamber can be easily applied to a cylinder having a small diameter bore.

  The spark plug holder 61 is formed of a copper-based material. Since the spark plug holder 61 is formed of a copper-based material, good heat transfer is realized, and charging of the first spark plug 47 is well prevented according to the good conductivity of the copper-based material. .

  In the internal combustion engine 24 according to the present embodiment, the first spark plug 47 is disposed above the peripheral wall 58a of the sub chamber partition 58 along the reference axis (cylinder axis C), and a passage formed on the inner surface of the peripheral wall 58a. The fuel injection valve 29 is disposed to be inclined to the reference axis toward the opening 72. The first spark plug 47 is disposed above the peripheral wall 58a of the sub chamber partition 58, whereas the fuel injection valve 29 is disposed around the circumferential wall 58a. Therefore, the first spark plug 47 and the fuel injection valve The width (diameter) of the sub-chamber 46 is reduced as compared with the case where 29 and 29 are arranged side by side. Therefore, the distance between the intake and exhaust valves disposed around the first spark plug 47 and the fuel injection valve 29 does not have to be increased, and the auxiliary chamber 46 is easily applied to a cylinder having a small diameter bore.

  The internal combustion engine 24 communicates with the opening of the passage 72 from the injection port of the fuel injection valve 29 and includes a fuel injection passage 71 having a diameter smaller than that of the fuel injection valve 29. Since the fuel injection passage 71 is formed in the small diameter passage, the fuel injection valve 29 is protected from the combustion pressure in the sub chamber 46. Thus, the durability of the fuel injection valve 29 is improved.

  The bottom wall 58 b of the sub chamber partition 58 bulges toward the combustion chamber 41 in a dome shape. The thickness of the bottom wall 58b increases toward the center. Therefore, a sufficient thickness is ensured for the bottom wall 58b. The bottom wall portion 58 b is cooled by the fuel injected from the fuel injection valve 29 and then exposed to high temperature according to the combustion in the combustion chamber 41. Since a sufficient thickness is secured to the bottom wall portion 58b, thermal energy can be more easily retained in the bottom wall portion 58b compared to when the bottom wall portion 58b is formed in a thin plate shape. As a result, the bottom wall 58b can be maintained at the optimum temperature regardless of fuel cooling and combustion. An increase in deposits and the like is prevented according to the maintenance of the temperature, and the durability of the sub-chamber partition 58 is improved.

  The wall thickness of the peripheral wall portion 58a of the sub-chamber partition wall 58 increases toward the bottom wall portion 58b. Since the peripheral wall 58a is connected to the bottom wall 58b in the region of the maximum wall thickness, heat transfer is promoted from the bottom wall 58b toward the peripheral wall 58a. As a result, the heat of the bottom wall portion 58b is efficiently diffused from the inner wall surface of the sub chamber hole portion 48a toward the cylinder head 27 which divides the sub chamber hole portion 48a.

  In the peripheral wall 58a of the auxiliary chamber partition 58, the lower end of the peripheral wall 58a connected to the bottom wall 58b penetrates the peripheral wall 58a in the thickness direction of the wall to connect the auxiliary chamber 46 to the combustion chamber 41. Is formed. Since the communication hole 67 penetrates the peripheral wall 58a at the lower end of the peripheral wall 58a in the thickness direction of the wall, a sufficient length is secured in the communication hole 67 by utilizing the increase in thickness. As a result, the combustion gas can be injected from the space in the sub chamber 46 toward the combustion chamber 41 in the optimal injection direction.

  24: internal combustion engine, 27: cylinder head, 41: combustion chamber, 46: secondary chamber, 47: (first) spark plug, 48: insertion hole, 48a: secondary chamber hole (vertical hole), 48b: plug hole , 56: step, 57: flange, 58: sub-chamber partition wall, 59: first seal member, 61: spark plug holder, 61a: cylindrical portion, 61b: screw portion, 62: thread groove of spark plug holder, 63 ... (a spark plug) thread groove, 64 ... second sealing member, 65b ... reduced diameter portion, 66 ... reduced diameter portion, 72 ... opening (passage).

Claims (7)

An auxiliary chamber hole (48a) on the combustion chamber (41) side and a plug larger in diameter than the auxiliary chamber hole (48a) and connected to the auxiliary chamber hole (48a) by a step (56) A cylinder head (27) having a hole (48b) and forming an insertion hole (48) opened on the wall surface of the combustion chamber (41);
A sub-chamber partition (58) having a flange (57) inserted in the sub-chamber hole (48a) to form a sub-chamber (46) communicating with the combustion chamber (41) and overlapping the step (56) ,
A first seal member (59) overlapping the flange (57);
The first seal member (59) is inserted into the plug hole (48b) and pressed at the tip toward the flange (57), and the tip of the spark plug (47) is held while holding the spark plug (47). A spark plug holder (61) positioned with respect to the sub chamber (46);
An internal combustion engine comprising a second seal member (64) sandwiched between the spark plug holder (61) and the inner wall of the plug hole (48b).   The internal combustion engine according to claim 1, wherein the first seal member (59) is an axial metal seal, and the second seal member (64) is a radial resin seal. Internal combustion engine.   The internal combustion engine according to claim 2, wherein the sub-chamber hole (48a) and the sub-chamber partition (58) contact each other and contract radially as they approach the combustion chamber (41). Internal combustion engine having a diameter portion (65b, 66). In the internal combustion engine according to claim 3,
The spark plug holder (61) is
A cylindrical portion (61a) formed coaxially with the spark plug (47) in a cylindrical shape and sandwiching the first seal member (59) between it and the flange (57) of the sub-chamber partition (58) at its tip;
It is connected to the upper end of the cylindrical portion (61a), has a cylindrical shape coaxially with the spark plug (47), and has a screw portion (61b) having a screw groove (62) on the outer periphery,
An internal combustion engine, wherein the second seal member (64) is mounted on the outer periphery of the cylindrical portion (61a).   5. Internal combustion engine according to claim 4, characterized in that the thread groove (62) of the spark plug holder (61) is arranged in a position overlapping the thread groove (63) of the spark plug (47). Internal combustion engine.   The internal combustion engine according to claim 5, wherein the cylinder head (27) is attached to the cylinder head (27) independently of the spark plug holder (61) and directed to an opening (72) formed in the sub-chamber partition (58). An internal combustion engine comprising a fuel injection valve (29) disposed in a posture inclined to a central axis of the spark plug (47).   The internal combustion engine according to claim 6, wherein the spark plug holder (61) is formed of a copper-based material.