JP2019132213A - Internal combustion engine - Google Patents

Abstract

To provide an internal combustion engine contributing to diversifying a technique of controlling an injection amount of a flame jet.SOLUTION: An internal combustion engine comprises an auxiliary chamber partition wall that has a peripheral wall part 58a contacting with an inner wall of a vertical hole extending from a combustion chamber along a central axial line Cp of an ignition plug, and a bottom wall part 58b continuing from the peripheral wall part 58a and expanding from the vertical hole toward the combustion chamber, and that communicates with the combustion chamber with an ignition point of the ignition plug covered with the peripheral wall part 58a and the bottom wall part 58b. The peripheral wall part 58a has a plurality of jetting holes 67 having a different thickness t in a circumferential direction around the central axial line Cp, and penetrating the peripheral wall part 58a in a thickness t direction to face to the combustion chamber.SELECTED DRAWING: Figure 7

Description

  The present invention has a peripheral wall portion in contact with the inner wall of the vertical hole extending from the combustion chamber along the center axis of the ignition plug, and a bottom wall portion continuously extending from the vertical wall toward the combustion chamber. In addition, the present invention relates to an internal combustion engine including a sub-chamber partition wall in which a peripheral wall portion and a bottom wall portion cover an ignition point of a spark plug and form a sub-chamber communicating with a combustion chamber.

  For example, Patent Document 1 discloses a plug cover that is attached to the tip of a spark plug, covers an ignition point of the spark plug, and is screwed into a vertical hole of a cylinder head. The plug cover forms an ignition chamber at the tip of the spark plug. The plug cover is formed with an injection hole that allows the ignition chamber and the combustion chamber to communicate with each other. When the air-fuel mixture is ignited in the ignition chamber, a flame jet is ejected from the nozzle hole into the combustion chamber.

JP 2009-270538 A

  Depending on the distance between the inner wall of the cylinder surrounding the combustion chamber and the plug cover, the hole diameter and arrangement density of the nozzle holes directed to the inner wall of the cylinder are set. Based on the hole diameter and arrangement density of the nozzle holes, the flame jet is homogenized in the combustion chamber. However, the hole diameter and arrangement density of the nozzle holes are limited depending on the material and strength of the plug cover, and diversification of the technique for controlling the injection amount of the flame jet is desired.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an internal combustion engine that contributes to diversification of techniques for controlling the injection amount of a flame jet.

  According to the first aspect of the present invention, a peripheral wall portion that is in contact with an inner wall of a vertical hole extending from the combustion chamber along the center axis of the ignition plug, and continuous from the peripheral wall portion toward the combustion chamber from the vertical hole. An internal combustion engine having a sub-chamber partition wall that forms a sub-chamber that covers an ignition point of a spark plug and communicates with the combustion chamber by the peripheral wall portion and the bottom wall portion. Is provided with an internal combustion engine having a plurality of injection holes that have different thicknesses in the circumferential direction around the central axis, and penetrate the peripheral wall portion in the thickness direction to face the combustion chamber.

  According to the second aspect, in addition to the configuration of the first side surface, the peripheral wall portion has an inner circumference having an axis that is eccentric from the outer axis.

  According to the third aspect, in addition to the configuration of the first or second side surface, in the peripheral wall portion, the hole diameter of the nozzle hole is large in a region having a large thickness compared to a region having a small thickness.

  According to the fourth aspect, in addition to the configuration of any one of the first to third side surfaces, the nozzle hole extends radially around the central axis.

  According to the fifth aspect, in addition to the configuration of any one of the first to fourth side surfaces, the peripheral wall portion faces the space between the ignition point and the nozzle hole and is directed to the central axis. A fuel injection passage is formed.

  According to the sixth aspect, in addition to the configuration of the fifth aspect, one intake valve that is disposed in the combustion chamber and that opens and closes one intake port that opens to the combustion chamber, and the combustion chamber is disposed. An exhaust valve that opens and closes one exhaust port that opens to the combustion chamber, and is orthogonal to a virtual plane that includes a central axis of the intake valve and a central axis of the exhaust valve, and the central axis of the ignition plug The central axis of the fuel injection passage is disposed in a virtual plane including

  According to the seventh aspect, in addition to the configuration of any one of the first to sixth aspects, the internal combustion engine includes the vertical hole that is opened to the space outside the combustion chamber at an open end, and the vertical hole. A cylinder head having a support surface extending outward along an imaginary plane perpendicular to the central axis from an edge of the vertical hole at an open end, and the sub-chamber partition wall is divided into a plurality of divided bodies in the circumferential direction And a flange that is continuous around the central axis and pressed against the support surface.

  According to the eighth aspect, in addition to the configuration of the eighth side surface, the hole diameter of the injection hole is larger on the inner surface side of the peripheral wall portion than on the combustion chamber side.

  According to the ninth aspect, in addition to the configuration of the seventh or eighth aspect, the divided body has a fractured surface that is generated by the fracture of the completed body of the sub-chamber partition wall and is recombined.

  According to the tenth aspect, in addition to the configuration of the seventh or eighth side surface, the mating surface of the divided body is formed with a recess that forms the nozzle hole when the mating surfaces overlap each other.

  According to the first aspect, the length of the nozzle hole can be adjusted according to the thickness of the peripheral wall portion of the sub-chamber partition wall. Since the ventilation resistance of the nozzle hole changes according to the length of the nozzle hole, the distribution of the flame jet in the combustion chamber can be controlled according to the setting of the wall thickness.

  According to the second aspect, different thicknesses in the circumferential direction can be easily realized in the peripheral wall portion according to the eccentricity of the outer periphery and the inner periphery.

  According to the third aspect, a larger number of flame jets are ejected from the nozzle holes as the hole diameter is larger. Even if a large amount of flame jet is injected, the thermal load stress is reduced if the thickness of the peripheral wall is large. The durability of the sub chamber partition is improved.

  According to the fourth aspect, since the outer periphery of the peripheral wall portion extends around the central axis in the combustion chamber, the flame jets in the fuel chamber can be homogenized when the nozzle holes are arranged radially around the central axis.

  According to the fifth aspect, since the thickness of the peripheral wall portion is different in the circumferential direction, the ignition space surrounded by the inner periphery of the peripheral wall portion is deviated from the center axis of the spark plug, and swirling of the injected fuel is achieved. Thus, stirring of air is promoted in the ignition space, and ignitability and combustion efficiency can be improved.

  According to the sixth aspect, the fuel injection valve connected to the fuel injection passage is along a virtual plane orthogonal to a virtual plane including the central axis of the intake valve and the central axis of the exhaust valve between the intake valve and the exhaust valve. The fuel injection valve can be sufficiently arranged without interfering with the intake valve and the exhaust valve.

  According to the seventh aspect, since the sub chamber partition is divided into a plurality of divided bodies in the circumferential direction, the processing conditions of the inner surface of the peripheral wall portion are relaxed, the degree of freedom of the shape of the ignition space is widened, and the sub chamber partition is Since the flange is positioned on the cylinder head, unlike the case where the peripheral wall is screwed into the vertical hole and fixed to the cylinder head, the peripheral wall can be made thinner and the restrictions on the shape of the individual divided bodies are relaxed. Can.

  According to the seventh aspect, since the hole diameter of the injection hole is reduced toward the combustion chamber, the injection force of the flame jet can be increased from the injection hole. As described above, the sub-chamber partition wall is divided into a plurality of divided bodies in the circumferential direction, so that processing from the inner surface of the peripheral wall portion serving as a so-called reverse hole can be realized.

  According to the ninth aspect, the mating surface of the divided body is formed with a fracture surface, and the divided bodies are joined with each other with a complicated three-dimensional fracture surface, so that leakage of the flame jet at the mating surface is prevented, Productivity and performance can be increased.

  According to the tenth aspect, since the injection hole is established only by overlapping the mating surfaces, the drilling operation by a drill or the like is omitted, and such a divided body can be formed by forging, so that productivity is improved. Can be improved.

1 is a side view schematically showing a structure of a motorcycle according to an embodiment of the present invention. It is a principal part expanded side view of FIG. FIG. 3 is an enlarged cross-sectional view taken along line 3-3 in FIG. 2. FIG. 4 is an enlarged cross-sectional view taken along line 4-4 of FIG. It is a principal part expanded sectional view of FIG. FIG. 6 is an enlarged cross-sectional view taken along line 6-6 of FIG. FIG. 7 is an enlarged cross-sectional view taken along line 7-7 in FIG. It is a conceptual diagram which shows roughly the manufacturing method of the subchamber partition which concerns on one specific example. It is an expansion perspective view which shows roughly the structure of the subchamber partition which concerns on other embodiment. FIG. 8 is an enlarged cross-sectional view of the sub chamber partition wall corresponding to FIG. 7 and schematically showing the hole diameter of the nozzle hole. It is a conceptual diagram which shows roughly the manufacturing method of the subchamber partition which concerns on one specific example. It is an enlarged plan view of a divided body schematically showing a mating surface of the divided body formed by forging. FIG. 6 is an enlarged cross-sectional view of an internal combustion engine according to another embodiment corresponding to FIG. 4.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Here, the top, bottom, front, back, left and right of the vehicle body are defined based on the eyes of the occupant riding the motorcycle.

  FIG. 1 schematically shows the overall 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 is individually coupled to a head pipe 13, a pair of left and right main frames 14 extending rearward and rearwardly from the head pipe 13, and rear ends of the individual main frames 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 are provided. . The down frame 16 is branched from the lower end of the upper frame 16a to the left and right at one upper 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 ends of the corresponding pivot frames 15. And a pair of left and right lower pipe frames 16b. The upper frame 16 a of the down frame 16 moves away from the main frame 14 as it moves backward from the head pipe 13.

  A front fork 18 that supports the front wheel WF is rotatably supported on the head pipe 13 so as to be rotatable around the axle 17. A handle bar 19 is coupled 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 the axle 21 is supported on the pivot frame 15 so as to be swingable around the support shaft 23. 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 in a space between the left and right pivot frames 15 and sandwiched between the left and right lower pipe frames 16b and connected to the pivot frame 15 and the lower pipe frame 16b. A cylinder block 26 that is coupled and extends upward from the crankcase 25 and has a forwardly inclined cylinder axis C, a cylinder head 27 that is coupled to the cylinder block 26, and a head cover 28 that is coupled to the cylinder head 27. . The crankcase 25 supports a crankshaft that rotates about a rotation axis S that extends 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 machine 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 a single cylinder internal combustion engine, for example. 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 is disposed in a space between the main frame 14 and the down frame 16, and injects fuel toward the combustion chamber as will be described later. A fuel pump 31 that is disposed in the space between the frames 16 and supplies fuel to the fuel injection valve 29 according to the generated pump pressure is attached as will be described later. The fuel injection valve 29 is connected to a fuel pipe 32 that extends from the discharge pipe 31 a of the fuel pump 31 and connects the fuel injection valve 29 and the fuel pump 31, and introduces fuel from the fuel pump 31 to the fuel injection valve 29.

  A fuel tank 34 is supported on the main frame 14 above the internal combustion engine 24. A primary fuel pump 35 that discharges fuel from the fuel tank 34 is disposed in the fuel tank 34. The suction pipe 31b of the fuel pump 31 extends from the primary fuel pump 35 and connects the primary fuel pump 35 and the fuel pump 31, and supplies fuel from the primary fuel pump 35 to the fuel pump 31 based on the pump pressure of the primary fuel pump 35. A primary fuel tube 36 is coupled. An occupant seat 37 is mounted on the vehicle body frame 12 behind the fuel tank 34. When driving the motorcycle 11, the occupant straddles the occupant seat 37.

  As shown in FIG. 2, the cylinder block 26 guides the linear reciprocation of the piston 38 along the cylinder axis C. Connected to the piston 38 is a connecting rod 39 connected to the crankshaft crank in the crankcase 25. The connecting rod 39 converts the linear reciprocating motion of the piston 38 into the rotational motion of the crankshaft.

  As shown in FIG. 3, the cylinder head 27 is connected to the combustion chamber 41 at the top position of the combustion chamber 41 formed between the piston 38 and the cylinder head 27, and is a sub chamber in which the injection port of the fuel injection valve 29 faces. 42 is provided. The cylinder head 27 receives the first spark plug 43 and receives the fuel injection valve 29 and the insertion hole 44 for arranging the center axis Cp of the first spark plug 43 on the cylinder axis C. A second inclination angle β that is larger than the first inclination angle α from the cylinder axis C by receiving the insertion hole 45 that arranges the central axis of the fuel injection valve 29 on the axis that falls at an inclination angle α and the second spark plug 46. A screw-in hole 47 for arranging the central axis of the second spark plug 46 is formed on the axis that falls down. The electrode (ignition point) 43 a of the first spark plug 43 faces the space in the sub chamber 42. The electrode of the second spark plug 46 faces the 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 43, the injection port faces the sub chamber 42, and the fuel is injected into the sub chamber 42 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 in the fuel injection passage 45a.

  As shown in FIG. 4, the internal combustion engine 24 opens and closes an intake port 27 a formed in the cylinder head 27 and communicating with an intake pipe 48 connected to the rear wall surface of the cylinder head 27 and opening in the combustion chamber 41. A pair of intake valves 49 for controlling the same and an exhaust port 27b that is formed in the cylinder head 27 and communicates with an exhaust pipe 51 connected to the front wall surface of the cylinder head 27 and opens in the combustion chamber 41 1 And a pair of exhaust valves 52. As shown in FIG. 2, the intake valve 49 is connected to an intake camshaft 53a that is positioned rearward of the cylinder axis C in a side view and has an axis parallel to the rotation axis S of the crankshaft. . In other words, the intake camshaft 53a is arranged behind the imaginary plane parallel to the rotation axis S of the crankshaft and including the cylinder axis C. Connected to the exhaust valve 52 is an exhaust camshaft 53b that is positioned in front of the cylinder axis C in a side view and has an axis parallel to the rotation axis S of the crankshaft. In other words, the exhaust camshaft 53b is disposed in front of the vehicle body relative to a virtual plane that is parallel to the rotation axis S of the crankshaft and includes the cylinder axis C. The intake camshaft 53a and the exhaust camshaft 53b are connected to a valve train 54 that transmits power from the crankshaft to the intake camshaft 53a and the exhaust camshaft 53b. The valve train 54 includes a sprocket 54a fixed to the intake camshaft 53a and a cam chain 54c wound around the sprocket 54b fixed to the exhaust camshaft 53b.

  As shown in FIG. 3, the intake camshaft 53 a has a rotation axis X that extends in parallel with the rotation axis S of the crankshaft from one side surface of the cylinder head 27 toward the other side surface. The fuel pump 31 is disposed on one side of the cylinder head 27 on an extension line of the intake camshaft 53a and connected to the intake camshaft 53a. The sprocket 54 a and the cam chain 54 c of the valve train 54 are disposed on the other side of the cylinder head 27. The fuel pump 31 is coaxial with the open / close valves disposed in the suction pipe 31b and the discharge pipe 31a, the plunger 55b for changing the volume of the pressure chamber 55a communicating with the suction pipe 31b and the discharge pipe 31a, and the intake camshaft 53a. And a reciprocating fuel pump that receives a driving force from the intake camshaft 53a and discharges high-pressure fuel.

  As shown in FIG. 5, the insertion hole 44 has a larger diameter than the sub chamber hole (vertical hole) 44a on the combustion chamber 41 side that opens at the wall surface of the combustion chamber 41 and the sub chamber hole 44a. A plug hole 44b connected to the sub chamber hole 44a by an annular step (support surface) 56 is provided. The sub chamber hole 44 a extends from the combustion chamber 41 along the central axis Cp of the first spark plug 43 and is opened to a space outside the combustion chamber 41 at an open end partitioned by a step 56. The step 56 extends outward from the edge of the sub chamber hole 44a at the open end of the sub chamber hole 44a along a virtual plane perpendicular to the central axis Cp of the first spark plug 43. Here, the step 56 is formed in an annular shape surrounding the circular open end. A sub chamber 42 that covers the ignition point 43 a of the first spark plug 43 and communicates with the tip of the first spark plug 43 is formed in the sub chamber hole 44 a, and a flange 57 that overlaps the step 56. A sub-chamber partition wall 58 having the above is inserted. The sub chamber partition wall 58 is made 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.

  An ignition plug holder that presses the first seal member 59 toward the flange 57 toward the flange 57 and positions the tip of the first spark plug 43 with respect to the sub chamber 42 while holding the first spark plug 43. 61 is inserted. Since the insertion hole 44 and the insertion hole 45 are individually 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 43, and has a cylindrical portion 61a sandwiching the first seal member 59 between the flange 57 of the sub chamber partition wall 58 at the tip, and an upper end of the cylindrical portion 61a. The first spark plug 43 is coaxially formed in a cylindrical shape and has a thread portion 61b 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 sandwiched between the sub chamber partition wall 58 and the spark plug holder 61 to block the space of the sub chamber 42 from the outside air. The first spark plug 43 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 43 in the axial direction.

  An annular second seal member 64 sandwiched between the inner wall of the spark plug holder 61 and the plug hole 44b 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 blocks the space in the insertion hole 44 on the combustion chamber 41 side from the space in the insertion hole 44 on the outside air side.

  The sub chamber partition wall 58 is inserted into a sub chamber hole 44a extending from the combustion chamber 41 along the cylinder axis (reference axis) C, and has a peripheral wall 58a that contacts the inner wall of the sub chamber hole 44a around the cylinder axis C. The sub-chamber 42 has a bottom wall portion 58b continuously extending from the sub-chamber hole portion 44a toward the combustion chamber 41. The sub-chamber 42 communicates with the combustion chamber 41 by the peripheral wall portion 58a and the bottom wall portion 58b. Form. The first spark plug 43 is disposed above the peripheral wall portion 58a. The bottom wall portion 58b swells in a dome shape toward the combustion chamber 41. Therefore, the thickness of the bottom wall portion 58b increases as it approaches 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 continuously 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 44 a has a reduced diameter portion 66 corresponding to the reduced diameter portion 65 b of the sub chamber partition wall 58 that decreases in the radial direction as it approaches the combustion chamber 41. The reduced diameter portion 65b of the sub chamber partition wall 58 and the reduced diameter portion 66 of the sub chamber hole 44a are in contact with each other to form a labyrinth structure. The first cylindrical portion 65a, the reduced diameter portion 65b, and the second cylindrical portion 65c are uniformly in contact with the inner wall of the sub chamber hole 44a.

  The wall thickness (wall thickness) of the peripheral wall portion 58a in the second cylindrical portion 65c increases toward the bottom wall portion 58b. Here, the 2nd cylinder part 65c forms the taber-shaped space which tapers as it goes to the bottom wall part 58b. A plurality of injection holes 67 are formed in the peripheral wall portion 58a at the lower end of the peripheral wall portion 58a so as to penetrate the peripheral wall portion 58a in the direction of wall thickness (wall thickness) and connect the sub chamber 42 to the combustion chamber 41. As shown in FIG. 6, a positioning protrusion 68 is formed on the outer periphery of the sub chamber partition wall 58 so as to protrude radially outward at a specific position in the circumferential direction continuously from the flange 57. The sub chamber hole 44a is formed with a recess 69 that is recessed from the step 56 at a specific position in the circumferential direction and receives the positioning protrusion 68 in the axial direction. By fitting the positioning protrusion 68 into the recess 69, the angular position of the sub chamber partition wall 58 can be positioned around the central axis Cp.

  As shown in FIG. 7, the peripheral wall portion 58 a of the sub chamber partition wall 58 has a different thickness t in the circumferential direction around the central axis Cp of the first spark plug 43. Here, the peripheral wall portion 58a is smaller than the outer periphery 71 of the circular contour cross section having the first diameter length R1 centered on the first axis Cf and the first diameter length R1 centered on the second axis Cs. The second axial center Cs is eccentric from the first axial center Cf. Based on such eccentricity, the wall thickness t of the peripheral wall portion 58a continuously changes. The nozzle holes 67 extend radially around the central axis Cp of the first spark plug 43. The nozzle holes 67 are arranged at equal intervals (equal angular intervals) around the central axis Cp. Here, the central axis of each nozzle hole 67 intersects the central axis Cp of the first spark plug 43. In the peripheral wall part 58a, the hole diameter of the injection hole 67 is large in a thick region compared to a small thick region.

  As shown in FIG. 5, a fuel injection passage 45 a that extends from the front end of the insertion hole 45 and has a smaller diameter than the fuel injection valve 29 is formed in the cylinder block 27. The central axis of the fuel injection passage 45 a intersects the cylinder axis C with an inclination angle smaller than the first inclination angle α of the axis Q of the fuel injection valve 29. By tilting the fuel injection valve 29 with respect to the fuel injection passage 45a in this way, 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 58a has a passage 73 that opens into a space between the ignition point 43a of the first spark plug 43 and the injection hole 67 as a part of the fuel injection passage 45a. As shown in FIG. 7, the passage 73 is directed to the central axis Cp of the first spark plug 43. The fuel injection passage 45 a leads from the injection port of the fuel injection valve 29 to the opening of the passage 73. The fuel injection valve 29 injects fuel toward the bottom wall portion 58 b in the sub chamber 42. The fuel injection area is formed so as to be out of the injection hole 67.

  Next, the operation of the internal combustion engine according to this embodiment will be described. If the intake valve 49 is opened when the piston 38 is lowered by the inertial force, air is introduced into the combustion chamber 41 from the intake port 27a. When the piston 38 rises, the volume of the combustion chamber 41 is reduced and the air is compressed. Fuel is injected from the fuel injection valve 29 toward the sub chamber 42. The injected fuel is introduced into the sub chamber 42 from the fuel injection passage 45a (including the passage 73). An air-fuel mixture is generated in the sub chamber 42. High pressure fuel is supplied from the fuel pump 31 to the fuel injection valve 29.

  The first spark plug 43 ignites the air-fuel mixture in the sub chamber 42. The air-fuel mixture burns in the sub chamber 42. The gas expands. As a result, a flame jet is ejected from the nozzle hole 67 of the sub chamber 42 into the combustion chamber 41. In this way, combustion is realized in the entire combustion chamber 41. In response to combustion, the air in the combustion chamber 41 expands and pushes down the piston 38. When the exhaust valve 52 is opened when the piston 38 is lifted by the inertial force, the burned gas is discharged from the exhaust port 27b. Such a series of operations is repeated to generate power in the internal combustion engine 24.

  In the internal combustion engine 24 according to the present embodiment, the peripheral wall portion 58 a of the sub chamber partition wall 58 has a different thickness t in the circumferential direction around the central axis Cp of the first spark plug 43. Thus, a plurality of injection holes 67 are formed in the peripheral wall portion 58a of the sub-chamber partition wall 58 so as to penetrate the peripheral wall portion 58a in the direction of the thickness t and face the combustion chamber 41. In the peripheral wall portion 58a of the sub chamber partition wall 58, the length of the nozzle hole 67 is adjusted according to the thickness t. Since the ventilation resistance of the nozzle hole 67 changes according to the length of the nozzle hole 67, the distribution of the flame jet can be controlled in the combustion chamber 41 according to the setting of the wall thickness t.

  In the present embodiment, the peripheral wall portion 58 a of the sub chamber partition wall 58 has an inner periphery 72 having a second axis Cs that is eccentric from the first axis Cf of the outer periphery 71. Depending on the eccentricity of the outer periphery 71 and the inner periphery 72, a different wall thickness t in the circumferential direction can be easily realized in the peripheral wall portion 58a. In particular, the peripheral wall 58a has a circular cross-sectional outer periphery 71 having a first diameter length R1 centered on the first axis Cf and a first diameter length R1 smaller than the first diameter length R1 centered on the second axis Cs. And the inner diameter 72 of the circular cross-section of the two-diameter length R2, and the second axis Cs is eccentric from the first axis Cf, so that the wall thickness t of the peripheral wall 58a continuously changes based on the eccentricity. To do.

  In the peripheral wall part 58a, the hole diameter of the injection hole 67 is large in a thick region compared to a small thick region. The larger the hole diameter, the more flame jets are ejected from the nozzle hole 67. Even if a large amount of flame jet is injected, the thermal load stress is reduced if the thickness of the peripheral wall portion 58a is large. As a result, the durability of the sub chamber partition wall 58 is improved.

  The nozzle holes 67 extend radially around the central axis Cp of the first spark plug 43. Since the outer periphery 71 of the peripheral wall portion 58a extends around the central axis Cp of the first spark plug 43 in the combustion chamber 41, when the nozzle holes 67 are arranged radially around the central axis Cp of the first spark plug 43, the fuel chamber The flame jet in 41 can be homogenized.

  In the present embodiment, fuel injection directed to the central axis Cp of the first spark plug 43 facing the space between the ignition point 43 a of the first spark plug 43 and the injection hole 67 on the peripheral wall portion 58 a of the sub chamber partition wall 58. A passage 73 of the passage 45a is formed. Since the wall thickness t of the peripheral wall portion 58a differs in the circumferential direction in the sub chamber partition wall 58, the ignition space surrounded by the inner periphery of the peripheral wall portion 58a is deviated from the central axis Cp of the first spark plug 43, and the swirling flow of the injected fuel As a result, the agitation of air is promoted in the ignition space, and the ignitability and combustion efficiency can be improved.

  Next, a method for manufacturing the sub chamber partition wall 58 according to this embodiment will be briefly described. The sub chamber partition wall 58 can be formed of a stainless steel material. The outer periphery 71 of the sub chamber partition wall 58 is cut out by, for example, cutting, and then the inner periphery 72 of the sub chamber partition wall 58 is cut out by, for example, drilling. As shown in FIG. 8, the flange 57, the outer surface 74a of the first cylindrical portion 65a, the reduced diameter portion 65b, and the outer surface 74b of the second cylindrical portion 65c are cut out in accordance with the cutting process. Thereafter, a space having a uniform diameter is drilled to the reduced diameter portion 65b by the first drill Dr. Thus, the first cylinder portion 65a is formed. Subsequently, the remaining space is drilled with a tapered second drill. In this way, the 2nd cylinder part 65c is formed. If the axis Cd of the first drill Dr and the second drill is eccentric from the axis Cf of the outer circumference 71, the inner circumference 72 having the axis Cs eccentric from the axis Cf can be easily cut out.

  In addition, a material in which a concentric outer peripheral surface is formed on the shaft core Cs of the inner periphery 72 is prepared in advance, and the outer periphery of the material is shaved around the shaft core Cf eccentric from the shaft core Cs to form the outer periphery 71. Good. The material may be molded based on forging, for example. Since the thickness of the material is kept constant in the circumferential direction around the axis Cs, the design of the material can be prevented from becoming complicated in the forging process.

  FIG. 9 schematically shows a sub-chamber partition wall 75 according to another embodiment. The sub chamber partition 75 has a peripheral wall portion 75a and a bottom wall portion 75b in the same manner as the sub chamber partition wall 58 described above. Similar to the above-described peripheral wall portion 58a, the peripheral wall portion 75a is connected to the combustion chamber 41 continuously from the first cylindrical portion 65a having the first outer diameter D1 that supports the flange 57 at the upper end and the lower end of the first cylindrical portion 65a. It has a reduced diameter portion 65b that decreases in the radial direction as it approaches, and a second cylindrical portion 65c having a second outer diameter D2 that is smaller than the first outer diameter D1 continuously from the lower end of the reduced diameter portion 65b. Hereinafter, the same reference numerals are given to the same components as those of the above-described sub chamber partition wall 58, and redundant description is omitted.

  The sub chamber partition wall 75 is divided into a plurality of divided bodies 76 and 77 in the circumferential direction around the central axis Cp of the first spark plug 43. For example, the mating surfaces 78 and 79 of the divided bodies 76 and 77 may be arranged in a virtual plane including the axis Cf of the outer periphery 71. At this time, in the completed body of the sub chamber partition wall 58, the flange 57 pressed against the step 56 continues in the circumferential direction around the axis Cf. Thus, since the sub chamber partition wall 75 is divided into a plurality of divided bodies 76 and 77 in the circumferential direction, the processing conditions of the inner surface of the peripheral wall portion 75a are relaxed, the degree of freedom of the shape of the ignition space is widened, and the sub chamber partition wall 75 is Since the flange 57 positions the cylinder head 27, unlike the case where the peripheral wall 75a is screwed into the vertical hole 44a and fixed to the cylinder head 27, the peripheral wall 75a is thinned and the individual divided bodies 76 are realized. 77, the shape constraints are relaxed.

  As shown in FIG. 10, in the sub chamber partition wall 75 according to the present embodiment, the hole diameter of the injection hole 67 is larger on the inner surface side of the peripheral wall portion 75a than on the combustion chamber 41 side. Thus, since the hole diameter of the injection hole 67 decreases toward the combustion chamber 41, the injection force of the flame jet from the injection hole 67 is increased. As described above, the sub-chamber partition wall 75 is divided into the plurality of divided bodies 76 and 77 in the circumferential direction, whereby processing from the inner surface of the peripheral wall portion 75a serving as a so-called reverse hole can be realized.

  Next, a method for manufacturing the sub chamber partition wall 75 according to this embodiment will be described. Here, for example, a so-called split connecting rod manufacturing method is employed. Specifically, a sub-partition body molded body 81 is prepared as in the sub-partition partition wall 58 described above during manufacture. The injection hole 67 may not be formed in the molded body 81. As shown in FIG. 11, a split line 82 is engraved on the outer periphery of the molded body 81. The dividing line 82 may be drawn in a virtual plane including the axis Cf of the outer periphery 71. Subsequently, a wedge type 83 for splitting is inserted into the internal space of the molded body 81. When a load is applied to the wedge mold 83 in the insertion direction, since the wedge mold 83 has a shape larger than the internal space of the molded body 81, the molded body 81 is divided into two along the split line 82. Thus, in each of the divided bodies 84a and 84b, a fracture surface 85 generated by the fracture of the finished body is formed as a mating surface. When the fracture surfaces 85 are overlapped and recombined, the divided bodies 84a and 84b are finished into finished bodies again. Thus, the sub chamber partition 75 is manufactured. The mating surfaces of the divided bodies 84a and 84b are formed by the fracture surface 85, and the divided bodies 84a and 84b are joined to each other by the complicated three-dimensional fracture surface 85, so that leakage of the flame jet is prevented at the mating surface. Productivity and performance can be increased.

  For the production of the sub-chamber partition wall 75, forging may be used for each of the divided bodies 76 and 77. At this time, as shown in FIG. 12, a recessed groove 86 that forms the injection hole 67 when the mating surfaces 78 and 79 overlap each other may be formed in the mating surfaces 78 and 79 of the divided body 76. Since the injection hole 67 is established only by the overlapping of the mating surfaces 78 and 79, the drilling operation by a drill or the like is omitted, and the divided bodies 76 and 77 can be formed by forging, so that productivity is improved. Will improve. In the forging process, the first cylindrical portion 65a having a space up to the reduced diameter portion 65b may be formed following the shape of the mold, and the remaining space may be drilled with a tapered second drill.

  In addition, as shown in FIG. 13, the sub-chamber partition walls 58 and 75 according to any of the embodiments can be applied to the internal combustion engine 24a including one intake valve 49 and one exhaust valve 52 for each cylinder. . At this time, the central axis 87 of the fuel injection passage 45a including the passage 73 is orthogonal to a virtual plane 88 including the central axis of the intake valve 49 and the central axis of the exhaust valve 52, and the central axis Cp of the first spark plug 43 is The virtual plane 89 is included. The fuel injection valve 29 connected to the fuel injection passage 45 a is arranged on a virtual plane 89 orthogonal to a virtual plane 88 including the central axis of the intake valve 49 and the central axis of the exhaust valve 52 between the intake valve 49 and the exhaust valve 52. Accordingly, the fuel injection valve 29 can be sufficiently disposed in the space without interfering with the intake valve 49 and the exhaust valve 52.

24 ... Internal combustion engine, 24a ... Internal combustion engine, 27 ... Cylinder head, 27a ... Intake port, 27b ... Exhaust port, 41 ... Combustion chamber, 42 ... Sub-chamber, 43 ... Spark plug (first spark plug), 43a ... Ignition point , 44a ... sub chamber hole (vertical hole), 45a ... fuel injection passage, 49 ... intake valve, 52 ... exhaust valve, 56 ... support surface (step), 57 ... flange, 58 ... sub chamber partition, 58a ... peripheral wall 58b ... bottom wall portion, 67 ... injection hole, 71 ... outer periphery, 72 ... inner periphery, 75 ... sub-chamber partition wall, 75a ... peripheral wall portion, 75b ... bottom wall portion, 76 ... divided body, 77 ... divided body, 78 ... Matching surface, 79 ... mating surface, 84a ... divided body, 84b ... divided body, 85 ... fracture surface, 86 ... hollow groove, 88 ... virtual plane (connecting the central axis of the intake valve and the central axis of the exhaust valve), 89 ... Virtual plane (perpendicular to virtual plane), Cf ... (outer) first axis , Cp ... (spark plug) central axis, Cs ... (inner circumference) of the second axial (of the peripheral wall portion) t ... thickness.

Claims (10)

A peripheral wall portion (58a; 75a) contacting the inner wall of the vertical hole (44a) extending from the combustion chamber (41) along the central axis (Cp) of the spark plug (43), and continuous from the peripheral wall portion (58a; 75a). A bottom wall portion (58b; 75b) projecting from the vertical hole (44a) toward the combustion chamber (41), and the peripheral wall portion (58a; 75a) and the bottom wall portion (58b; 75b). ) And a sub-chamber partition wall (58; 75) that forms a sub-chamber (42) that covers the ignition point (43a) of the spark plug (43) and communicates with the combustion chamber (41). In
The peripheral wall portion (58a; 75a) has a different thickness (t) in the circumferential direction around the central axis (Cp) and penetrates the peripheral wall portion (58a; 75a) in the direction of the thickness (t). An internal combustion engine having a plurality of nozzle holes (67) facing the combustion chamber (41).   2. The internal combustion engine according to claim 1, wherein the peripheral wall portion (58 a; 75 a) has an inner periphery (72) having an axis (Cs) eccentric from an axis (Cf) of the outer periphery (71). An internal combustion engine.   3. The internal combustion engine according to claim 1, wherein, in the peripheral wall portion (58 a; 75 a), the hole diameter of the injection hole (67) is larger in a region having a larger thickness (t) than in a region having a smaller thickness (t). Is an internal combustion engine characterized by being large.   The internal combustion engine according to any one of claims 1 to 3, wherein the nozzle hole (67) extends radially around the central axis (Cp).   5. The internal combustion engine according to claim 1, wherein the peripheral wall portion (58 a; 75 a) faces the space between the ignition point (43 a) and the injection hole (67). An internal combustion engine having a fuel injection passage (45a) directed toward the central axis (Cp). The internal combustion engine according to claim 5,
A single intake valve (49) disposed in the combustion chamber (41) for controlling opening and closing of a single intake port (27a) that opens to the combustion chamber (41);
An exhaust valve (52) disposed in the combustion chamber (41) for controlling the opening and closing of one exhaust port (27b) opening to the combustion chamber (41);
In a virtual plane (89) perpendicular to the virtual plane (88) including the central axis of the intake valve (49) and the central axis of the exhaust valve (52) and including the central axis (Cp) of the spark plug (43). The internal combustion engine, wherein a central axis of the fuel injection passage (45a) is disposed. The internal combustion engine according to any one of claims 1 to 6,
The vertical hole (44a) opened to the space outside the combustion chamber (41) at the open end, and the central axis (Cp) from the edge of the vertical hole (44a) at the open end of the vertical hole (44a) A cylinder head (27) having a support surface (56) extending outward along a virtual plane orthogonal to
The sub-chamber partition wall (58; 75) is divided into a plurality of divided bodies (76, 77; 84a, 84b) in the circumferential direction, and continues around the central axis (Cp) to support the support surface (56). An internal combustion engine having a flange (57) pressed against the engine.   The internal combustion engine according to claim 7, wherein the hole diameter of the injection hole (67) is larger on the inner surface side of the peripheral wall portion (75a) than on the combustion chamber (41) side.   9. The internal combustion engine according to claim 7, wherein the divided body (84 a, 84 b) has a fracture surface (85) that is generated when the completed body of the sub-chamber partition wall (75) is broken and recombined. A characteristic internal combustion engine. The internal combustion engine according to claim 7 or 8, wherein the nozzle holes (67) are formed when the mating surfaces (78, 79) overlap with the mating surfaces (78, 79) of the divided bodies (76, 77). An internal combustion engine characterized in that a recess groove (86) is formed.