JP6640178B2 - Internal combustion engine - Google Patents

Description

  The present invention further includes a peripheral wall portion which is inserted into a vertical hole extending from the combustion chamber along a reference axis and which is in contact with an inner wall of the vertical hole around the reference axis, and which is continuous from the peripheral wall portion, and wherein the combustion is performed from the vertical hole. The present invention relates to an internal combustion engine having a bottom wall projecting toward a chamber, and a sub-chamber partition forming a sub-chamber communicating with the combustion chamber by the peripheral wall and the bottom wall.

  For example, Patent Document 1 discloses a sub-chamber engine (internal combustion engine). In the sub-chamber engine, the tip of the spark plug and a passage leading from the fuel injection valve are arranged on the ceiling surface of the sub-chamber. When fuel is injected, the spark plug ignites the mixture in the sub-chamber. The flame jet due to the combustion radially blows into the combustion chamber from an injection hole formed in the bottom wall of the sub-chamber partition wall. The flame jet stably burns the lean mixture in the combustion chamber, so that high-efficiency and low-NOx combustion is realized.

JP 2008-169706 A JP-A-2004-108225

  In the device described in Patent Document 1, since the spark plug and the fuel injection valve are arranged side by side, the width (diameter) of the sub-chamber must be wide, and the interval between the intake valve and the exhaust valve must be wide. It was difficult to apply to a cylinder having a bore.

  The present invention has been made in view of the above circumstances, and provides an internal combustion engine that contributes to downsizing of a sub-chamber and realizes a sub-chamber that can be easily applied to a cylinder having a small-diameter bore. With the goal.

According to the first aspect of the present invention, a peripheral wall portion that is inserted into a vertical hole extending from a combustion chamber along a reference axis and is in contact with an inner wall of the vertical hole around the reference axis, and continuously from the peripheral wall portion, An internal combustion engine having a bottom wall projecting from the vertical hole toward the combustion chamber, and including a sub-chamber partition that forms a sub-chamber communicating with the combustion chamber with the peripheral wall and the bottom wall. A spark plug disposed above the peripheral wall along a reference axis, and a fuel injection valve disposed in a position inclined toward the reference axis toward an opening formed on an inner surface of the peripheral wall, The fuel injection valve has an injection direction facing the bottom wall portion in the sub-chamber, has a communication hole around the bottom wall portion connecting the sub-chamber to the combustion chamber, and is positioned on the outer periphery of the peripheral wall portion. A projection is formed, and the positioning projection is located at a specific position in the circumferential direction in the vertical hole. Internal combustion engine that match fit in the recess provided as recessed, is provided.

According to the second aspect, a peripheral wall portion that is inserted into a vertical hole extending from the combustion chamber along a reference axis and is in contact with an inner wall of the vertical hole around the reference axis, and the vertical hole is continuous from the peripheral wall portion. A bottom wall projecting toward the combustion chamber from the peripheral wall and the bottom wall, the internal combustion engine having a sub-chamber partition that forms a sub-chamber communicating with the combustion chamber, A spark plug disposed above the peripheral wall along the same, and a fuel injection valve disposed at a position inclined toward a reference axis toward an opening formed on the inner surface of the peripheral wall. A positioning protrusion is formed on the outer periphery, and the positioning protrusion fits into a concave portion provided in the vertical hole at a specific position in the circumferential direction.

According to the first and second aspects, the spark plug is arranged above the peripheral wall, while the fuel injection valve is arranged around the peripheral wall, so that the ignition plug and the fuel injection valve are arranged side by side. The width (diameter) of the sub-chamber can be reduced as compared with the case where it is arranged. Therefore, the interval between the intake valve and the exhaust valve disposed around the ignition plug and the fuel injection valve does not need to be widened, and the sub-chamber can be easily applied to a cylinder having a small-diameter bore. In addition, positioning projections are formed on the outer periphery of the peripheral wall portion, and the positioning projections are fitted into recesses provided in the vertical holes so as to be depressed at specific positions in the circumferential direction. Can be

FIG. 1 is a side view schematically showing a structure of a motorcycle according to one embodiment of the present invention. FIG. 2 is a sectional view taken along line 2-2 of FIG. 1. FIG. 2 is an enlarged plan view near a fuel tank of the motorcycle. It is a principal part enlarged side view of FIG. FIG. 5 is an enlarged sectional view taken along line 5-5 of FIG. FIG. 6 is an enlarged sectional view of a main part of FIG. 5.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Here, it is assumed that the up, down, front, rear, left and right of the vehicle body are defined based on the eyes of the occupant riding the motorcycle.

  FIG. 1 schematically shows an entire configuration of a motorcycle (a specific example of a saddle-ride type vehicle) according to an embodiment of the present invention. A body frame 12 of the motorcycle 11 includes a head pipe 13, a pair of left and right main frames 14 extending rearward and downward from the head pipe 13, and a main frame 14 which is individually coupled to a rear end of each main frame 14. A pair of left and right pivot frames 15 extending downward from the rear end and connected to each other 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 has one upper frame 16a extending downward from the head pipe 13 at the center in the left and right direction in the vehicle width direction, and branches down left and right from the lower end of the upper frame 16a and is individually connected to the lower end of the corresponding pivot frame 15. And a pair of left and right lower pipe frames 16b. The upper frame 16 a of the down frame 16 moves downward from the main frame 14 as it moves backward from the head pipe 13.

  On the head pipe 13, a front fork 18 that supports the front wheel WF so as to be rotatable around an axle 17 is steerably supported. A handlebar 19 is connected to the front fork 18 above the head pipe 13. A swing arm 22 that supports the rear wheel WR so as to be rotatable around an axle 21 is supported by the pivot frame 15 so as to be swingable around a support shaft 23. The support shaft 23 extends horizontally in the vehicle width direction.

  The internal combustion engine 24 is mounted on the 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 that extends upward from the crankcase 25 and is inclined forward, includes a cylinder head 27 coupled to the cylinder block 26, and a head cover 28 coupled 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 via a transmission (not shown). An auxiliary device such as an AGC (DC generator) is connected to one end of the crankshaft and is covered with a case cover 25a. Here, the internal combustion engine 24 is configured as, for example, a single cylinder internal combustion engine. The cylinder block 26, the cylinder head 27, and the head cover 28 are arranged between the main frame 14 and the down frame 16 in a side view that is projected parallel to the rotation axis S of the crankshaft on a projection plane orthogonal to the rotation axis S of the crankshaft. Placed in Hereinafter, a detailed description of a structure common to a general internal combustion engine may be omitted.

  On one side of the cylinder head 27, a fuel injection valve 29 which is disposed in a space between the main frame 14 and the down frame 16 and injects fuel toward the combustion chamber as described later, A fuel pump 31 that is disposed in a space between the frames 16 and supplies fuel to the fuel injection valve 29 in accordance with a generated pump pressure, as described later, is attached. The fuel injection valve 29 is connected to a fuel pipe 32 extending from a discharge pipe 31 a of the fuel pump 31, connecting 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 cooling of the internal combustion engine 24 are attached to the upper frame 16 a of the down frame 16. The left radiator 33 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 cooling water 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 a cooling jacket of the internal combustion engine 24. As shown in FIG. 2, the fuel pump 31 is arranged inside a virtual plane PP that is in contact with the outer surface of the main frame 14 and the outer surface of the case cover 25a. The protrusion of the fuel pump 31 from the virtual plane PP that is in contact with the main frame 14 and the case cover 25a from the left outside is avoided. The fuel pump 31 can be protected from collision with another object.

  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 fuel from the fuel tank 34 is arranged. The primary fuel pump 35 and the fuel pump 31 are connected to the suction pipe 31 b of the fuel pump 31 so as to extend from the primary fuel pump 35, and the 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 seat 37 is mounted on the 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 a fuel tank 34 in a plan view based on a viewpoint existing at infinity above. In other words, the fuel pump 31 is arranged inside the curved vertical surface VP that is parallel to the direction of gravity and is in contact with the curved outer edge of the fuel tank 34. Thus, the protrusion of the fuel pump 31 from the outer shape of the fuel tank 34 is avoided. The fuel pump 31 can be protected from collision with another object.

  As shown in FIG. 4, the cylinder block 26 guides a linear reciprocating movement of the piston 38 along the cylinder axis C. A connecting rod 39 connected to the crank of the crankshaft in the crankcase 25 is connected to the piston 38. The connecting rod 39 converts the linear reciprocating motion of the piston 38 into a rotary 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) for individually opening and closing the intake ports and a pair of exhaust valves (not shown) for individually opening and closing the exhaust ports are arranged. The intake valve is connected to an intake camshaft 42a located behind the cylinder axis C in a side view and having an axis parallel to the rotation axis S of the crankshaft. In other words, the intake camshaft 42a is disposed behind the virtual plane including the cylinder axis C and parallel to the rotation axis S of the crankshaft. The exhaust valve is connected to an exhaust camshaft 42b located forward of the cylinder axis C in a side view and having an axis parallel to the rotation axis S of the crankshaft. In other words, the exhaust camshaft 42b is disposed parallel to the rotation axis S of the crankshaft and ahead of the virtual plane including the cylinder axis C. As will be 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 train 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 extending infinitely including the central axis) is disposed on the cylinder axis C in a vehicle side view, and passes through the head pipe 13 in a vehicle side view. In other words, the center axis of the fuel injection valve 29 is arranged in an imaginary plane that is parallel to the rotation axis S of the crankshaft and includes the cylinder axis C, and is parallel to the rotation axis S of the crankshaft and An imaginary plane including the central axis of the head pipe 13 crosses the head pipe 13. The fuel pump 31 is disposed at a position shifted 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 arranged parallel to the rotation axis S of the crankshaft and behind the virtual plane including the cylinder axis C, and the fuel pipe 32 is parallel to the rotation axis S of the crankshaft. It is arranged in a space between a virtual plane that contacts the main frame 14 from the front of the vehicle body and a virtual plane that is parallel to the rotation axis S of the crankshaft and contacts 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 the axis, and is connected to the fuel injection valve 29. The protrusion of the fuel pipe 32 toward the outside is suppressed.

  As shown in FIG. 5, the cylinder head 27 is provided with a sub-chamber 46 which communicates with the combustion chamber 41 at the top of the combustion chamber 41 and faces the injection port of the fuel injection valve 29. The cylinder head 27 receives the first spark plug 47, receives the insertion hole 48 for arranging the center axis of the first spark plug 47 on the cylinder axis C, and receives the fuel injection valve 29, and receives the first injection plug 47 from the cylinder axis C. The insertion hole 49 that arranges the center axis of the fuel injection valve 29 on the axis that falls at the inclination angle α, and the second spark plug 51 are received and the second inclination angle β that is larger than the first inclination angle α from the cylinder axis C is set. A screw hole 52 is formed on the falling axis to arrange the center axis of the second spark plug 51. The electrode of the first spark plug 47 faces the space in the sub chamber 46. The electrode of the second spark plug 51 faces a space in the combustion chamber 41. The fuel injection valve 29 is held in a posture inclined with respect to the central axis of the first spark plug 47, faces the injection port to the sub chamber 46, and injects fuel toward the combustion chamber 41 in the sub chamber 46. Here, the gap between the upper end of the fuel injection valve 29 and the fuel pump 31 can be secured by laying the fuel injection valve 29 on the injection passage 49a in this manner.

  The intake camshaft 42a has a rotation axis X extending parallel to the rotation axis S of the crankshaft from one side surface to the other side surface of the cylinder head 27. The fuel pump 31 is arranged on one side surface of the cylinder head 27 on an extension of the intake camshaft 42a and is connected to the intake camshaft 42a. The sprocket 44a and the cam chain 45 of the valve train 43 are arranged on the other side of the cylinder head 27. The fuel pump 31 is coaxial with an on-off valve disposed on the suction pipe 31b and the discharge pipe 31a, a plunger 54 for changing the volume of the pressure chamber 53 communicating with the suction pipe 31b and the discharge pipe 31a, and a camshaft 42a for intake. And a cam member 55 that generates reciprocating motion of the plunger 54, and is configured as a reciprocating fuel pump that receives a driving force from the intake camshaft 42a and discharges high-pressure fuel.

  As shown in FIG. 6, the insertion hole 48 has a larger diameter than the sub-chamber hole (vertical hole) 48 a on the combustion chamber 41 side opening on the wall surface of the combustion chamber 41 and the sub-chamber hole 48 a. It has a plug hole 48b connected to the sub chamber hole 48a by an annular step 56. A sub-chamber 46 is formed in the sub-chamber hole 48 a. The sub-chamber 46 communicates with the combustion chamber 41 and has a flange 57 overlapping the step 56. The sub-chamber partition 58 is formed of, for example, a stainless steel material. 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 against the plug hole portion 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 ignition plug holder 61.

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

  An annular second seal member 64 sandwiched between the ignition 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 shuts off the space inside the insertion hole 48 on the combustion chamber 41 side and the space inside the insertion hole 48 on the outside air side.

  The sub-chamber partition wall 58a is inserted into the sub-chamber hole 48a extending from the combustion chamber 41 along the cylinder axis C (reference axis) and is in contact with the inner wall of the sub-chamber hole 48a around the cylinder axis C; 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. To form The first spark plug 47 is disposed above the peripheral wall 58a. The bottom wall portion 58 b expands in a dome shape toward the combustion chamber 41. Therefore, the thickness of the bottom wall portion 58b increases as approaching the center (cylinder axis C).

  The peripheral wall portion 58a of the sub-chamber partition wall 58 has a first cylindrical portion 65a having a first outer diameter D1 that supports the flange 57 at the upper end, and a radial direction as it approaches the combustion chamber 41 from 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 48a has a reduced-diameter portion 66 corresponding to the reduced-diameter portion 65b of the sub-chamber partition 58, which radially reduces as it approaches the combustion chamber 41. The reduced diameter portion 65b of the sub chamber partition 58 and the reduced diameter portion 66 of the sub chamber hole 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 uniformly contact the inner wall of the sub chamber hole 48a.

In the second cylindrical portion 65c, the wall thickness of the peripheral wall portion 58a increases toward the bottom wall portion 58b. Here, the second cylindrical portion 65c forms a space tape path over shape tapering toward the bottom wall portion 58b. At the lower end of the peripheral wall portion 58a, a communication hole 67 that penetrates the peripheral wall portion 58a in the thickness direction of the wall and connects the sub-chamber 46 to the combustion chamber 41 is formed. The communication hole 67 extends radially from the cylinder axis C. A positioning projection 68 is formed on the outer periphery of the sub-chamber partition wall 58 and protrudes radially outward at a specific circumferential position continuously from the flange 57. A concave portion 69 which is recessed from the step 56 at a specific position in the circumferential direction and receives the positioning protrusion 68 is formed in the sub chamber hole 48a. By fitting the positioning protrusion 68 into the concave portion 69, the angular position of the sub-chamber partition 58 can be positioned around the cylinder axis C.

A fuel injection passage 71 that extends from the front end of the insertion hole 49 and has a smaller diameter than the fuel injection valve 29 is formed in the cylinder block 27. 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. By inclining the fuel injection valve 29 with respect to the fuel injection passage 71 in this manner, 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 58a has, as an extension of the fuel injection passage 71, a passage 72 that opens to the inner surface of the peripheral wall 58a on the combustion chamber 41 side with respect to the reduced diameter portion 65b. The fuel injection passage 71 communicates with the opening of the passage 72 from the injection port of the fuel injection valve 29. The fuel injection valve 29 injects fuel toward the bottom wall 58b in the sub chamber 46. The fuel injection area is formed so as to deviate from the communication hole 67 .

  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 arranged in a 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 mounted on one side surface of the cylinder head 27 together with the fuel injection valve 29, interference between the fuel pump 31 and the main frame 14 is avoided without relatively 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 arranged close to each other, the fuel pipe 32 for supplying 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 rotation axis S of the crankshaft on a projection plane orthogonal to the rotation axis S of the crankshaft. Since the main frame 14 and the down frame 16 approach each other as heading toward the head pipe 13, when the center axis of the fuel injection valve 29 passes through 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 center axis of the fuel injection valve 29 is disposed on the cylinder axis C in a side view projected parallel to the rotation axis S of the crankshaft on a projection plane orthogonal to the rotation axis S of the crankshaft. The fuel pipe 32 is disposed between the main frame 14 and the down frame 16 in a side view. As described above, a sufficient space is secured on the central axis of the fuel injection valve 29 between the main frame 14 and the down frame 16, so that a sufficient space is provided between the main frame 14 and the down frame 16 and the fuel pump 31. Space is formed. Therefore, good maintenance of the fuel pump 31 is ensured. The fuel pipe 32 is well protected between the main frame 14 and the down frame 16.

  The fuel pump 31 is connected to a fuel tank 34 supported by the main frame 14 via a primary fuel pipe 36, and is projected parallel to the rotation axis S of the crankshaft on a projection plane orthogonal to the rotation axis S of the crankshaft. , And is disposed at a position shifted 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. You.

  The motorcycle 11 includes a radiator 33 attached to the down frame 16 in front of the fuel injection valve 29 in the vehicle body. The radiator 33 is separated from the fuel pump 31 in front of the fuel pump 31. The fuel pump 31 is prevented from being 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 that is disposed on an extension of the intake camshaft 42a supported by the cylinder head 27 and receives a driving force from the intake camshaft 42a. The reciprocating fuel pump 31 supplies a high-pressure fuel in accordance with the driving force of the high-speed intake camshaft 42a. Therefore, fuel combustion chamber injection (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 of the combustion chamber 41 and faces the injection port of the fuel injection valve 29. Since the combustion chamber 41 is closest to the camshafts 42a and 42b at the top position, the fuel injection valve 29 is arranged as close as possible to the intake camshaft 42a. Thus, the distance between the fuel injection valve 29 and the fuel pump 31 is reduced 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 first ignition plug 47 facing the space in the sub chamber 46 at a second inclination angle β. A second spark plug having a central axis and facing a space in the combustion chamber; In realizing the combustion chamber injection, 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 the internal combustion engine 24 according to the present embodiment, the cam shaft 42a, 42b extend toward the one side surface of the cylinder head 2 7 on the other side, the other side face of the cylinder head 27, a crank shaft cam shaft 42a, and 42b A valve train 43 for transmitting power is arranged. Since the fuel pump 31 is disposed at one end of the camshafts 42a and 42b, and the valve train 43 is disposed at the other end of the camshafts 42a and 42b, a good weight balance of the internal combustion engine 24 is ensured. In addition, the maintainability of the valve train 43 is well maintained without being hindered by the fuel injection valve 29 or the fuel pump 31.

  In the present embodiment, the first seal member 59 overlaps the flange 57 of the sub-chamber partition wall 58, and the ignition plug holder 61 is inserted into the plug hole 48 b of the insertion hole 48, and the first seal member 61 is positioned at the front end toward the flange 57. The member 59 is pressed, and the second seal member 64 is sandwiched between the ignition plug holder 61 and the inner wall of the plug hole 48b. The first sealing member 59 is axially sandwiched between the ignition 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 ignition plug holder 61, so that the pressure leakage of the sub-chamber 46 is prevented. Is reliably prevented. Moreover, since the flange 57 pressed against the step 56 functions as a sealing member, even if the peripheral wall 58a of the sub-chamber partition 58 that is in contact with the inner wall of the sub-chamber hole 48a is thin, the peripheral wall 58a is pressed by the axial pressing force. No deformation is caused, and pressure leakage from the combustion chamber 41 to the inner wall of the sub chamber hole 48a is reliably prevented. Further, since the second seal member 64 is disposed axially outward of the flange 57 of the sub-chamber partition wall 58 and the first seal member 59, gas leakage in the combustion chamber 41 and gas leakage in the sub-chamber 46 are reduced. Exhibits a 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 over the entire circumference around the cylinder axis C is an axial metal seal. The second seal member 64 sandwiched between the cylindrical portion 61a and the inner wall of the insertion hole 48 is a radial resin seal. Since the first seal member 59 is a metal seal, even if the first seal member 59 is sandwiched between the flange 57 of the sub-chamber partition wall 58 and the spark plug holder 61 and is exposed to an axial load, the first seal member 59 is reliably leaked under pressure. To prevent On the other hand, since the second seal member 64 is a resin seal, the second seal member 64 can be easily attached and detached, and the maintainability is improved.

In the internal combustion engine 24 according to the present embodiment, the sub chamber holes 48a and the auxiliary chamber partition wall 58 of the insertion hole 48 is each other contact each other, the reduced diameter portion 66,65b to shrink radially closer to the combustion chamber 41 Respectively. By forming a labyrinth structure between the inner wall of the sub-chamber hole 48a and the outer surface of the sub-chamber partition 58, pressure leakage from the combustion chamber 41 through the inner wall of the sub-chamber hole 48a is prevented. As a result, the load on the second seal member 64 is reduced, and the seal structure is simplified.

The ignition plug holder 61 according to the present embodiment is formed in a cylindrical shape coaxially with the first ignition plug 47, and has a cylindrical portion 61 a that sandwiches the first seal member 59 between the front end and the flange 57 of the sub-chamber partition 58, It is formed coaxially in a cylindrical shape to the first spark plug 47 is connected to the upper end of the cylindrical portion 61a, and a threaded portion 61b having screw groove 62 on the outer periphery, the second seal member on the outer circumference of the cylindrical portion 61 a 64 Is attached. Since the spark plug holder 61 is formed in a cylindrical shape coaxial with the first spark plug 47, the difference in outer shape between the sub chamber 46 and the spark plug holder 61 can be reduced, and as a result, the distance between the intake valve and the exhaust valve can be reduced. Does not need to be widened, 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 arranged at a position axially overlapping the screw groove 63 of the first spark plug 47. The first spark plug 47 is connected to the spark plug holder 61 by a screw groove 63, and good heat transfer from the first spark plug 47 to the spark plug holder 61 is realized in the area of the screw groove 63. Similarly, the spark plug holder 61 is connected to the cylinder head 27 by a screw groove 62, and in the region of the screw groove 62, good heat transfer from the spark plug holder 61 to the cylinder head 27 is realized. Thus, 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 center 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 an inclined position. Since the spark plug holder 61 is disposed axially above the sub-chamber partition 58, the fuel injection valve 29 is disposed around the sub-chamber partition 58, so that the ignition plug holder 61 and the fuel injection valve 29 are separated. The width (diameter) of the sub chamber 46 is reduced as compared with the case where the sub chambers 46 are arranged side by side. Therefore, the interval between the intake valve and the exhaust valve disposed around the first spark plug 47 and the fuel injection valve 29 does not need to be widened, and the sub chamber can be easily applied to a cylinder having a small bore.

  The spark plug holder 61 is formed from 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 portion 58a of the sub-chamber partition wall 58 along the reference axis (cylinder axis C), and a passage formed on the inner surface of the peripheral wall portion 58a. The fuel injection valve 29 is arranged so as to be inclined toward the reference axis toward the opening 72. The first spark plug 47 is disposed above the peripheral wall 58a of the sub-chamber partition wall 58, whereas the fuel injection valve 29 is disposed around the peripheral wall 58a. The width (diameter) of the sub-chamber 46 is reduced as compared to the case where the sub-chambers 29 are arranged side by side. Therefore, the interval between the intake valve and the exhaust valve disposed around the first spark plug 47 and the fuel injection valve 29 does not need to be widened, and the sub chamber 46 is easily applied to a cylinder having a small-diameter bore.

  The internal combustion engine 24 has a fuel injection passage 71 that communicates with the opening of the passage 72 from the injection port of the fuel injection valve 29 and has a smaller diameter than the fuel injection valve 29. Since the fuel injection passage 71 is formed as a 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 portion 58 b of the sub-chamber partition wall 58 expands in a dome shape toward the combustion chamber 41. The thickness of the bottom wall portion 58b increases toward the center. Therefore, a sufficient thickness is secured in the bottom wall portion 58b. After being cooled by the fuel injected from the fuel injection valve 29, the bottom wall portion 58b is exposed to a high temperature in accordance with the combustion in the combustion chamber 41. Since the bottom wall 58b has a sufficient thickness, heat energy is more likely to remain on the bottom wall 58b than when the bottom wall 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 or combustion. An increase in deposits and the like is prevented in accordance with the maintenance of the temperature, and the durability of the sub-chamber partition 58 is improved.

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

  In the peripheral wall portion 58a of the sub-chamber partition wall 58, a communication hole 67 that penetrates the peripheral wall portion 58a in the thickness direction of the wall at the lower end of the peripheral wall portion 58a connected to the bottom wall portion 58b and connects the sub-chamber 46 to the combustion chamber 41. Is formed. Since the communication hole 67 penetrates the peripheral wall portion 58a in the thickness direction of the wall at the lower end of the peripheral wall portion 58a, a sufficient length is secured in the communication hole 67 by utilizing the increased 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 optimum injection direction.

  29: fuel injection valve, 41: combustion chamber, 47: (first) ignition plug, 48a: sub chamber hole (vertical hole), 58: sub chamber partition, 58a: peripheral wall, 58b: bottom wall, 67 ... Communication hole, 72: opening (passage), C: reference axis (cylinder axis).

Claims (2)

A peripheral wall portion (58a) that is inserted into a vertical hole (48a) extending from the combustion chamber (41) along the reference axis (C) and that contacts the inner wall of the vertical hole (48a) around the reference axis (C); A bottom wall (58b) extending from the vertical hole (48a) toward the combustion chamber (41) continuously from the peripheral wall (58a), and the peripheral wall (58a) and the bottom wall; An internal combustion engine having a sub-chamber partition (58) that forms a sub-chamber (46) communicating with the combustion chamber (41) with the portion (58b);
A spark plug (47) disposed above the peripheral wall (58a) along a reference axis (C);
A fuel injection valve (29) arranged in a posture inclined toward a reference axis (C) toward an opening (72) formed on the inner surface of the peripheral wall portion (58a);
With
The fuel injection valve (29) has an injection direction facing the bottom wall (58b) in the sub-chamber (46),
A communication hole (67) for connecting the sub-chamber (46) to the combustion chamber (41) around the bottom wall (58b) ;
A positioning projection (68) is formed on the outer periphery of the peripheral wall portion (58a). The positioning projection (68) is formed in a concave portion (69) provided in the vertical hole (48a) so as to be depressed at a specific position in the circumferential direction. fitting match internal combustion engine, wherein the Rukoto. A peripheral wall portion (58a) that is inserted into a vertical hole (48a) extending from the combustion chamber (41) along the reference axis (C) and that contacts the inner wall of the vertical hole (48a) around the reference axis (C); A bottom wall (58b) extending from the vertical hole (48a) toward the combustion chamber (41) continuously from the peripheral wall (58a), and the peripheral wall (58a) and the bottom wall; An internal combustion engine having a sub-chamber partition (58) that forms a sub-chamber (46) communicating with the combustion chamber (41) with the portion (58b);
A spark plug (47) disposed above the peripheral wall (58a) along a reference axis (C);
A fuel injection valve (29) arranged in a posture inclined toward a reference axis (C) toward an opening (72) formed on the inner surface of the peripheral wall portion (58a);
With
A positioning projection (68) is formed on the outer periphery of the peripheral wall portion (58a). The positioning projection (68) is formed in a concave portion (69) provided in the vertical hole (48a) so as to be depressed at a specific position in the circumferential direction. An internal combustion engine, which is fitted.

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