JP2006329092A - Auxiliary chamber type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an auxiliary chamber type internal combustion engine capable of reducing cooling loss. <P>SOLUTION: This auxiliary chamber type internal combustion engine 100 is provided with a main combustion chamber 63, an auxiliary chamber 161, a first communicating passage 162, and an ignition plug 29. The auxiliary chamber 161 is adjacent to the main combustion chamber 63. The first communicating passage 161 communicates the main combustion chamber 63 with the auxiliary chamber 161. The ignition plug 29 ignites new air air-fuel mixture introduced into the auxiliary chamber 161 from the main combustion chamber 63 through the first communicating passage 162 to generate first flame and second flame. The first flame has a first peak. The first peak is a peak of radiation speed. The radiation speed is speed when flame is radiated into the main combustion chamber 63 from the auxiliary chamber 161 through the first communicating passage 162. The second flame has a second peak. The second peak is a peak being later than the first peak and a peak of radiation speed being larger than the first peak. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sub-chamber internal combustion engine.

Conventionally, a sub-combustion type internal combustion engine including a main combustion chamber and a sub-combustion chamber provided adjacent to the main combustion chamber has been proposed (see, for example, Patent Document 1).
JP-A-60-45716 (Page 1-5, Figure 1-12)

  In the technique of Patent Document 1, the sub-chamber internal combustion engine is further provided with a communication passage that communicates the main combustion chamber and the sub-combustion chamber. The flame generated by igniting the fresh air mixture in the auxiliary combustion chamber is emitted in a torch form from the auxiliary combustion chamber to the main combustion chamber via the communication path.

  However, in the technique of Patent Document 1, unburned fuel tends to remain in the vicinity of the communication path in the main combustion chamber. And when combustion is performed in the main combustion chamber, the unburned fuel may flow back to the sub-combustion chamber, so that the cooling loss tends to increase.

  An object of the present invention is to provide a sub-chamber internal combustion engine that can reduce cooling loss.

  The sub-chamber internal combustion engine according to the present invention includes a main combustion chamber, a sub-combustion chamber, a first communication path, and an ignition unit. The auxiliary combustion chamber is adjacent to the main combustion chamber. The first communication passage communicates the main combustion chamber and the auxiliary combustion chamber. The ignition unit ignites the fresh air mixture introduced from the main combustion chamber to the sub-combustion chamber via the first communication passage, and generates a first flame and a second flame. The first flame has a first peak. The first peak is a peak of radiation speed. The radiation speed is a speed at which a flame is radiated from the auxiliary combustion chamber to the main combustion chamber via the first communication passage. The second flame has a second peak. The second peak is a peak after the first peak, and is a peak having a higher radiation speed than the first peak.

  In the sub-chamber internal combustion engine, the ignition unit ignites the fresh air mixture introduced from the main combustion chamber to the sub-combustion chamber via the first communication passage, and generates a first flame and a second flame. Here, since the radiation speed of the first flame is slower than that of the second flame, the spread angle when radiated to the main combustion chamber tends to increase. For this reason, the unburned fuel staying in the vicinity of the first communication path can be burned by the first flame, and the unburned fuel staying in the vicinity of the first communication path can be reduced.

  The second flame is generated after the first flame, and the radiation speed thereof is faster than the radiation speed of the first flame. For this reason, the fresh air-fuel mixture in the main combustion chamber can be burned by the second flame while the unburned fuel staying in the vicinity of the first communication path is reduced.

  In the sub-chamber internal combustion engine according to the present invention, when the pressure in the main combustion chamber becomes larger than the pressure in the sub-combustion chamber, unburned fuel remaining in the vicinity of the first communication path is reduced. Therefore, it is possible to suppress the unburned fuel from flowing back to the auxiliary combustion chamber. For this reason, a cooling loss can be reduced.

<Configuration and Operation of Sub-chamber Internal Combustion Engine as Premise of the Present Invention>
The configuration and operation of the sub-chamber internal combustion engine 1 which is the premise of the present invention will be described with reference to FIGS.

(Schematic configuration of sub-chamber internal combustion engine)
FIG. 1 shows a cross-sectional view of the sub-chamber internal combustion engine 1.

  The sub-chamber internal combustion engine 1 mainly includes a main combustion chamber 63, a sub-combustion chamber 61, a spark plug (ignition part) 29, a first communication passage 62, a second fuel injection valve (second fuel supply part) 27, and intake and exhaust. Provide mechanism.

  The main combustion chamber 63 is a chamber surrounded by the cylinder head 20, the cylinder block 10 and the piston 3. The cylinder head 20 is formed with an intake port 23 for supplying fresh air mixture to the main combustion chamber 63 and an exhaust port 24 for discharging burned gas from the main combustion chamber 63 as exhaust gas. .

  An intake valve 21 is provided downstream of the intake port 23 as an intake / exhaust mechanism. On the other hand, an exhaust valve 22 is disposed upstream of the exhaust port 24. The intake cam shaft 21b / exhaust cam shaft 22b fixed to the intake cam shaft 21b / exhaust cam shaft 22b rotating in conjunction with the rotation of the crankshaft are arranged above the intake valve 21 / exhaust valve 22. Then, the intake valve 21 / exhaust valve 22 are opened and closed.

  The second fuel injection valve 27 is a valve that injects fuel into the intake port 23. The second fuel injection valve 27 is provided so as to penetrate the intake port 23. The tip of the second fuel injection valve 27 protrudes into the intake port 23.

  The auxiliary combustion chamber 61 is a chamber provided adjacent to the main combustion chamber 63 and is surrounded by the auxiliary combustion chamber wall 64. More specifically, a substantially cylindrical auxiliary combustion chamber wall 64 is disposed in a space formed between the intake port 23 and the exhaust port 24 in the cylinder head 20 to form an auxiliary combustion chamber 61. Further, a first communication passage 62 that connects the main combustion chamber 63 and the sub-combustion chamber 61 is formed on the bulged hemispherical bottom surface of the sub-combustion chamber wall 64. The spark plug 29 is provided such that a tip end portion 29 a protrudes into the auxiliary combustion chamber 61.

(Schematic operation of sub-chamber internal combustion engine)
In the sub-chamber internal combustion engine 1, pressurized fuel is supplied to the second fuel injection valve 27 in the intake stroke. The second fuel injection valve 27 injects fuel into fresh air introduced into the intake port 23. Thereby, a fresh air mixture is generated. Then, the intake valve 21 is opened by the intake cam 21a, and the fresh air mixture is introduced from the intake port 23 into the main combustion chamber 63.

  In the compression stroke, the fresh air mixture is compressed in the main combustion chamber 63, and a part of the fresh air mixture in the main combustion chamber 63 is transferred from the main combustion chamber 63 to the auxiliary combustion chamber via the first communication passage 62. 61.

  By the spark plug 29, the fuel in the auxiliary combustion chamber 61 is ignited and burned at a predetermined timing. The combustion gas (flame) in the auxiliary combustion chamber 61 is radiated in a torch shape to the main combustion chamber 63 via the first communication passage 62 (see FIG. 2), and the homogeneous fresh air mixture in the main combustion chamber 63 is combusted. .

  In the expansion stroke, the piston 3 is pushed down by the combustion pressure generated by burning the fresh air mixture.

  In the exhaust stroke, the exhaust valve 22 is opened by the exhaust cam 22a, and the burned gas burned in the main combustion chamber 63 is discharged to the exhaust port 24 as exhaust gas.

(Detailed configuration of auxiliary combustion chamber)
2 and 3 are enlarged sectional views of the auxiliary combustion chamber 61. FIG. 2 and 3 are cross-sectional views taken along a plane including the cylinder axis CA1.

  As shown in FIG. 2, the auxiliary combustion chamber 61 is a chamber surrounded by the auxiliary combustion chamber wall 64. The auxiliary combustion chamber 61 has a substantially cylindrical shape with the cylinder axis CA1 as the central axis. Further, the bottom surface of the auxiliary combustion chamber 61 swells in a hemispherical shape. A plurality of first communication passages 62 that communicate the main combustion chamber 63 and the sub-combustion chamber 61 are formed on the bulged hemispherical bottom surface of the sub-combustion chamber wall 64. The first communication passage 62 is inclined downward at an acute angle with the cylinder axis CA <b> 1 in the direction from the sub-combustion chamber 61 to the main combustion chamber 63. Thereby, a flame can be efficiently radiated from the auxiliary combustion chamber 61 to the main combustion chamber 63.

  On the other hand, the auxiliary combustion chamber 61 is provided with a spark plug 29 at a position facing the first communication passage 62 and at an upper position. The spark plug 29 is disposed so as to penetrate the auxiliary combustion chamber wall 64 from the upper side to the lower side, and extends from the upper part of the auxiliary combustion chamber 61 toward the volume center of the auxiliary combustion chamber 61. Further, the tip end portion 29 a of the spark plug 29 is disposed in the sub-combustion chamber 61 in the vicinity of the central axis CA <b> 1 of the sub-combustion chamber 61 and away from the main combustion chamber 63. A tip end portion 29 a of the spark plug 29 protrudes into the auxiliary combustion chamber 61. The spark plug 29 ignites the fresh air mixture in the auxiliary combustion chamber 61 by generating a spark at the tip end portion 29 a. Thus, the spark plug 29 can efficiently ignite and burn the fresh air mixture in the auxiliary combustion chamber 61.

(Detailed operation of secondary combustion chamber)
In the compression stroke, a part of the homogeneous fresh air mixture in the main combustion chamber 63 is introduced from the main combustion chamber 63 to the sub-combustion chamber 61 via the first communication passage 62. Then, the spark plug 29 ignites the fresh air mixture by generating sparks. The ignited fresh air-fuel mixture reaches the first communication passage 62 as a flame.

  The flame that has reached the first communication passage 62 is radiated in the form of a torch from the auxiliary combustion chamber 61 to the main combustion chamber 63 via the first communication passage 62 as flames B7 and B8.

  Here, since the first communication passage 62 is provided on the main combustion chamber 63 side with respect to the spark plug 29, the flames B7 and B8 are directed from the sub-combustion chamber 61 toward the main combustion chamber 63 (oblique in FIG. 2). Radiated downward). That is, the flames B7 and B8 are efficiently radiated from the auxiliary combustion chamber 61 to the main combustion chamber 63.

  Further, the flames B7 and B8 have a relatively high radiation speed. The radiation speed is a speed at which a flame is radiated from the auxiliary combustion chamber 61 to the main combustion chamber 63 via the first communication passage 62. For this reason, the flames B 7 and B 8 have a sharp shape with a relatively small spread angle when radiated to the main combustion chamber 63, and the propagation direction is mainly away from the vicinity of the first communication passage 62. As a result, the contact area and contact time between the unburned fuels F1 and F2 in the vicinity of the first communication passage 62 and the flames B7 and B8 are reduced, and the unburned fuels F1 and F2 are hardly burned. It remains in the vicinity of the passage 62.

  The flames B7 and B8 radiated from the auxiliary combustion chamber 61 to the main combustion chamber 63 burn the fresh air mixture in the main combustion chamber 63.

  Next, in the expansion stroke, the new air-fuel mixture in the main combustion chamber 63 burns, so that the pressure in the main combustion chamber 63 rapidly increases. Here, although the main combustion chamber 63 and the sub-combustion chamber 61 are communicated with each other by the first communication passage 62, the pressure in the main combustion chamber 63 is suddenly increased. Temporarily higher than the pressure.

  For this reason, as shown in FIG. 3, the unburned fuels F <b> 1 and F <b> 2 remaining in the vicinity of the first communication passage 62 flow into the auxiliary combustion chamber 61 from the main combustion chamber 63 via the first communication passage 62. The unburned fuels F1 and F2 that have flowed into the auxiliary combustion chamber 61 tend to ignite in the auxiliary combustion chamber 61 at hot portions such as the tip portion 29a of the spark plug 29 and the inner wall surface 64a. Thereby, unburned fuel F1, F2 may be burned without contributing to the combustion in the main combustion chamber 63, and the cooling loss tends to increase.

<Configuration and Operation of Sub-chamber Internal Combustion Engine According to First Embodiment of the Present Invention>
The sub-chamber internal combustion engine 100 according to the first embodiment of the present invention will be described with a focus on differences from the sub-chamber internal combustion engine 1 which is the premise of the present invention, with reference to FIGS.

(Schematic configuration of sub-chamber internal combustion engine)
The sub-chamber internal combustion engine 100 includes a sub-combustion chamber 161 instead of the sub-combustion chamber 61. The auxiliary combustion chamber 161 is surrounded by the auxiliary combustion chamber wall 164. Specifically, a substantially cylindrical auxiliary combustion chamber wall 164 is disposed in a space formed between the intake port 23 and the exhaust port 24 in the cylinder head 20, thereby forming the auxiliary combustion chamber 161. In addition, a first communication passage 162 that communicates between the main combustion chamber 63 and the sub-combustion chamber 161 is formed on the expanded hemispherical bottom surface of the sub-combustion chamber wall 164. The spark plug 129 is provided so that a tip end portion 129 a protrudes into the auxiliary combustion chamber 161.

  Other points are the same as those of the sub-chamber internal combustion engine 1 which is the premise of the present invention.

(Schematic operation of sub-chamber internal combustion engine)
This is the same as the sub-chamber internal combustion engine 1 which is the premise of the present invention.

(Detailed configuration of auxiliary combustion chamber)
5 to 8 are enlarged sectional views of the auxiliary combustion chamber 161. FIG. 5 to 8 are cross-sectional views taken along a plane including the cylinder axis CA1. In addition, the same component as said subchamber internal combustion engine 1 used as a premise is shown with the same number.

  The sub-combustion chamber 161 has a first sub-combustion chamber 161a, a second communication passage 161b, and a second sub-combustion chamber 161c. The first sub-combustion chamber 161a has a substantially circular cross section perpendicular to the cylinder axis CA1. The first auxiliary combustion chamber 161 a is provided adjacent to the main combustion chamber 63, and is a chamber surrounded by the auxiliary combustion chamber wall 164 and the baffle plate 165. The first sub-combustion chamber 161a has a substantially hemispherical shape with the cylinder axis CA1 as the central axis. A plurality of first communication passages 162 communicating the main combustion chamber 63 and the first sub-combustion chamber 161a are formed on the expanded hemispherical bottom surface of the sub-combustion chamber wall 164. The first communication passage 162 is inclined downward at an acute angle with the cylinder axis CA1 in the direction from the first sub-combustion chamber 161a toward the main combustion chamber 63. Thereby, a flame can be efficiently radiated from the first sub-combustion chamber 161a to the main combustion chamber 63.

  The second sub-combustion chamber 161c is provided at a position farther from the main combustion chamber 63 than the first sub-combustion chamber 161a and adjacent to the first sub-combustion chamber 161a. The second sub-combustion chamber wall 164 and the baffle plate It is a room surrounded by 165. The second sub-combustion chamber 161c has a substantially cylindrical shape with the cylinder axis CA1 as the central axis.

  Here, the baffle plate 165 is a plate member that divides the auxiliary combustion chamber 161 into a first auxiliary combustion chamber 161a and a second auxiliary combustion chamber 161c. The volume of the second auxiliary combustion chamber 161c is larger than the volume of the first auxiliary combustion chamber 161a. As a result, the volume of the fresh air mixture in the second subcombustion chamber 161c is larger than the volume of the fresh air mixture in the first subcombustion chamber 161a, so that the propulsive force of the flame generated in the first subcombustion chamber 161a In comparison with this, the propulsive force of the flame generated in the second sub-combustion chamber 161c can be increased.

  The baffle plate 165 is opened near the cylinder shaft CA1 to form a second communication path 161b. The second communication passage 161b communicates the first sub-combustion chamber 161a and the second sub-combustion chamber 161c. The area of the cross section perpendicular to the flow path direction of the second communication path 161 b is substantially equal to the area of the cross section perpendicular to the flow path direction of the first communication path 162.

  On the other hand, the auxiliary combustion chamber 161 is provided with a spark plug 129 from an upper position to a position approaching the first communication path 162. The spark plug 129 is disposed so as to penetrate the sub-combustion chamber wall 164 from above to below. The spark plug 129 penetrates from the upper part to the lower part of the second subcombustion chamber 161c, and penetrates from the upper part to the lower part of the second communication passage 161b, and from the upper part of the first subcombustion chamber 161a to the vicinity of the center of the volume. It extends to. Thereby, it is difficult to prevent the flame from being radiated from the first sub-combustion chamber 161a to the second sub-combustion chamber 161c via the second communication passage 161b.

  Further, the tip portion 129a of the spark plug 129 is disposed in the first sub-combustion chamber 161a in the vicinity of the cylinder shaft CA1 and away from the main combustion chamber 63. A tip portion 129a of the spark plug 129 protrudes into the first sub-combustion chamber 161a. Further, in the auxiliary combustion chamber 161, the protruding member 164c extends from a portion of the auxiliary combustion chamber wall 164 close to the main combustion chamber 63 to a position far from the main combustion chamber 63 (in a direction toward the tip portion 129a). The protruding member 164c and the auxiliary combustion chamber wall 164 are electrically connected, and the tip end portion 129a and the protruding member 164c are electrically insulated. The spark plug 129 ignites the fresh air mixture in the first auxiliary combustion chamber 161a by generating a spark between the tip portion 129a and the protruding member 164c. As a result, the spark plug 129 can efficiently ignite and burn the fresh air mixture in the first auxiliary combustion chamber 161a.

  The tip portion 129a of the spark plug 129 and the baffle plate 165 are electrically insulated.

(Detailed operation of secondary combustion chamber)
In the compression stroke, a part of the homogeneous fresh air mixture in the main combustion chamber 63 is introduced from the main combustion chamber 63 to the first sub-combustion chamber 161a via the first communication passage 162. The spark plug 129 ignites the fresh air mixture by generating sparks. The ignited fresh air-fuel mixture reaches not only the first communication path 162 but also the second communication path 161b as a flame.

  The flame that has reached the first communication path 162 is emitted as a flame B101, B102 (first flame) from the first auxiliary combustion chamber 161a to the main combustion chamber 63 via the first communication path 162. Here, since the first communication passage 162 is provided on the main combustion chamber 63 side with respect to the tip portion 129a of the spark plug 129, the flames B101 and B102 travel from the first sub-combustion chamber 161a to the main combustion chamber 63. Radiated in the direction (diagonally downward in FIG. 5). That is, the flames B101 and B102 are efficiently radiated from the first sub-combustion chamber 161a to the main combustion chamber 63.

  The flame that has reached the second communication passage 161b is emitted as a flame B103 from the first sub-combustion chamber 161a to the second sub-combustion chamber 161c via the second communication passage 161b. Here, since the second communication passage 161b is provided on the side away from the main combustion chamber 63 with respect to the tip portion 129a of the spark plug 129, the flame B103 is directed from the first sub-combustion chamber 161a to the main combustion chamber 63. Radiated in the direction away (upward in FIG. 5).

  Here, since the volume of the first sub-combustion chamber 161a is smaller than the volume of the second sub-combustion chamber 161c, the volume of the first sub-combustion chamber 161a is larger than the volume of the fresh air mixture in the second sub-combustion chamber 161c. The volume of the fresh air mixture is decreasing. Further, since the ignited fresh air-fuel mixture reaches not only the first communication passage 162 but also the second communication passage 161b as a flame, the ignited fresh air-fuel mixture reaches only the first communication passage 62 as a flame. Compared to the case (see FIG. 2), the propulsive force of the flame reaching the first communication path 162 is smaller. For these reasons, the radiation speed of the flames B101 and B102 is slower than that of the flames B7 and B8. The radiation speed is a speed at which a flame is radiated from the first sub-combustion chamber 161a to the main combustion chamber 63 via the first communication path 162. For this reason, the flames B101 and B102 have a relatively large spread angle when radiated to the main combustion chamber 63. Further, the propagation direction of the flames B101 and B102 is a direction that mainly spreads in the vicinity of the first communication path 162. As a result, the contact area and contact time between the unburned fuels F101 and F102 in the vicinity of the first communication passage 162 and the flames B101 and B102 are large, and most of the unburned fuels F101 and F102 are flames B101 and B102. Is changed to burned fuels F103 and F104 (see FIG. 6).

  On the other hand, the fresh air-fuel mixture in the second auxiliary combustion chamber 161c is ignited and burned by the flame B103. Here, since the propulsive force of the flame reaching the second communication path 161b is also small, the speed at which the flame B103 is emitted is also slow. For this reason, the flame B103 has a relatively large spread angle when radiated to the second sub-combustion chamber 161c, and its propagation direction is mainly in the direction of spreading near the second communication passage 161b. . Thereby, the fresh air mixture in the vicinity of the second communication passage 161b is easily burned by the flame B103. Further, since the volume of the second auxiliary combustion chamber 161c is smaller than the volume of the main combustion chamber 63, the volume of the fresh air mixture in the second auxiliary combustion chamber 161c is equal to the volume of the fresh air mixture in the main combustion chamber 63. It is smaller than that. As a result, even if the speed at which the flame B103 is emitted is slow, the combustion period in the second sub-combustion chamber 161c is sufficiently shortened, and the pressure in the second sub-combustion chamber 161c increases rapidly. Furthermore, since the volume of the second sub-combustion chamber 161c is larger than the volume of the first sub-combustion chamber 161a, the volume of the fresh air mixture in the second sub-combustion chamber 161c is equal to the fresh air mixture in the first sub-combustion chamber 161a. It is larger than the qi volume. For this reason, the propulsive force of the flame produced | generated in the 2nd subcombustion chamber 161c becomes large compared with the propulsive force of the flame produced | generated in the 1st subcombustion chamber 161a.

  As shown in FIG. 6, the combustion gas (flame) in the second sub-combustion chamber 161c is radiated to the first sub-combustion chamber 161a as the flame B104 via the second communication passage 161b. The flame B104 collides with the inner wall surface 164a of the first auxiliary combustion chamber 161a and propagates as flames B105 and B106. Furthermore, the flames B105 and B106 reach the first communication path 162. As shown in FIG. 7, the flames B105 and B106 that have reached the first communication passage 162 are formed as flames B107 and B108 (second flame) from the first subcombustion chamber 161a via the first communication passage 162 and the main combustion chamber 63. Radiated in a torch shape.

  Here, since the flames B107 and B108 are radiated in the direction from the first subcombustion chamber 161a toward the main combustion chamber 63 (the obliquely downward direction in FIG. 7), the flames B107 and B108 are emitted from the first subcombustion chamber 161a. It is efficiently radiated to the main combustion chamber 63.

  Also, the flames B107 and B108 have a higher radiation speed than the flames B101 and B102. For this reason, the flames B107 and B108 have a sharp shape with a relatively small spread angle when radiated to the main combustion chamber 63, and the propagation direction thereof is mainly away from the vicinity of the first communication passage 162. As a result, the contact area and contact time between the burned fuels F103 and F104 in the vicinity of the first communication passage 162 and the flames B107 and B108 are reduced, but most of the unburned fuels F101 and F102 are already burned fuel F103. , F104, the remaining unburned fuel F101, F102 in the vicinity of the first communication path 162 is reduced.

  Then, the flames B107 and B108 radiated from the first auxiliary combustion chamber 161a to the main combustion chamber 63 burn the fresh air mixture in the main combustion chamber 63.

  Next, in the expansion stroke, the new air-fuel mixture in the main combustion chamber 63 burns, so that the pressure in the main combustion chamber 63 rapidly increases. Here, the main combustion chamber 63 and the first sub-combustion chamber 161a communicate with each other through the first communication passage 162. However, since the pressure in the main combustion chamber 63 increases rapidly, the pressure in the main combustion chamber 63 is the first pressure. The pressure temporarily becomes higher than the pressure in the auxiliary combustion chamber 161a.

  For this reason, as shown in FIG. 8, the burned fuels F103 and F104 remaining in the vicinity of the first communication passage 162 flow from the main combustion chamber 63 into the first sub-combustion chamber 161a via the first communication passage 162. . The burned fuels F103 and F104 that have flowed into the first subcombustion chamber 161a are mostly ignited hot in the first subcombustion chamber 161a at high temperature portions such as the tip portion 129a and the inner wall surface 164a of the spark plug 129. Absent. Thereby, it is reduced that the burned fuels F103 and F104 are burned without contributing to the combustion in the main combustion chamber 63, and the cooling loss is reduced.

(Characteristics related to sub-chamber internal combustion engine)
(1)
Here, the spark plug 129 ignites the fresh air mixture introduced from the main combustion chamber 63 to the sub-combustion chamber 161 via the first communication passage 162, and generates flames B101 and B102 and flames B107 and B108. . Here, since the flames B101 and B102 have a radiation speed slower than that of the flames B107 and B108, the spread angle when emitted to the main combustion chamber 63 tends to be large. For this reason, most of the unburned fuels F101 and F102 staying in the vicinity of the first communication path 162 are burned by the flames B101 and B102 and changed into burned fuels F103 and F104. Further, the flames B107 and B108 are generated after the flames B101 and B102, and the radiation speed thereof is faster than that of the flames B101 and B102. For this reason, the fresh air mixture in the main combustion chamber 63 is combusted by the flames B107 and B108 in a state where the unburned fuel F101 and F102 hardly stay in the vicinity of the first communication passage 162.

  Thus, when the pressure in the main combustion chamber 63 becomes larger than the pressure in the sub-combustion chamber 161, the unburned fuels F101 and F102 staying in the vicinity of the first communication passage 162 are reduced. The fuels F101 and F102 are prevented from flowing back to the first auxiliary combustion chamber 161a. For this reason, the cooling loss is reduced.

(2)
Here, since the volume of the first sub-combustion chamber 161a is smaller than the volume of the second sub-combustion chamber 161c, the volume of the fresh air mixture in the first sub-combustion chamber 161a is the fresh air of the second sub-combustion chamber 161c. It is smaller than the volume of the mixture. The spark plug 129 is provided in the first sub-combustion chamber 161a. Thereby, the flame generated by the spark plug 129 igniting the fresh air mixture in the first auxiliary combustion chamber 161a is dispersed in the first communication path 162 and the second communication path 161b, so the radiation speed of the flames B101 and B102 And the flames B101 and B102 reach the vicinity of the first communication passage 162. For this reason, the unburned fuels F101 and F102 staying in the vicinity of the first communication passage 162 are combusted by the flames B101 and B102.

  The flame B103 radiated from the first subcombustion chamber 161a to the second subcombustion chamber 161c via the second communication passage 161b ignites the fresh air mixture in the second subcombustion chamber 161c. Here, the volume of the fresh air mixture in the second auxiliary combustion chamber 161c is larger than the volume of the fresh air mixture in the first auxiliary combustion chamber 161a. For this reason, the propulsive force of the flame produced | generated in the 2nd subcombustion chamber 161c becomes large compared with the propulsive force of the flame produced | generated in the 1st subcombustion chamber 161a. As a result, flames B107 and B108 having a higher radiation speed than the flames B101 and B102 are radiated from the auxiliary combustion chamber 161 to the main combustion chamber 63 via the first communication passage 162. That is, the radiation speeds of the flames B107 and B108 are faster than the radiation speeds of the flames B101 and B102.

(3)
Here, the area of the cross section perpendicular to the flow path direction of the second communication path 161 b is substantially equal to the area of the cross section perpendicular to the flow path direction of the first communication path 162. For this reason, when the combustion gas (flame) in the first auxiliary combustion chamber 161a reaches the first communication path 162 and the second communication path 161b, the flames B101, B102, and B103 are stably emitted. Further, the flame B103 causes the fresh air mixture in the second auxiliary combustion chamber 161c to combust in a stable state with little cycle fluctuation.

(Modification of the first embodiment)
(A) The spark plug (not shown) is configured to generate a spark at the tip portion similar to the tip portion 29a instead of generating a spark between the tip portion 129a and the protruding member 164c. Also good. That is, a tip portion similar to the tip portion 29a in the spark plug may protrude into the first sub-combustion chamber 161a.

  Even in this case, if the spark plug passes through the second communication passage 161b in a substantially cylindrical shape in the flow path direction, the flame is transferred from the first sub-combustion chamber 161a to the second sub-combustion chamber 161c via the second communication passage 161b. Is not easily prevented from being emitted.

  (B) As shown in FIGS. 9 to 11, in the auxiliary combustion chamber 161i of the auxiliary chamber internal combustion engine 100i, the second communication passage 161bi is formed in the vicinity of the cylinder axis CA1 instead of being formed in the vicinity of the cylinder axis CA1. It may be formed at an offset position. In other words, the baffle plate 165i is opened at a position offset from the cylinder axis CA1 to form a plurality of second communication passages 161bi. 10 is a cross-sectional view taken along the line XX in FIG.

  At this time, the second communication passage 161bi is offset with respect to the central axis (cylinder axis CA1) of the second sub-combustion chamber 161c and is inclined with respect to the cylinder radial direction R1 (see FIG. 10) of the second sub-combustion chamber 161c. is doing. Therefore, a swirl flow A1 (see FIG. 9) is generated in the second sub-combustion chamber 161c by the flames B103i and B109i radiated from the first sub-combustion chamber 161a to the second sub-combustion chamber 161c via the second communication passage 161bi. Is done. As a result, the combustion period in the second sub-combustion chamber 161c is shortened, and the pressure in the second sub-combustion chamber 161c increases more rapidly. As a result, a flame with a higher radiating speed is radiated from the first subcombustion chamber 161a to the main combustion chamber 63 via the first communication passage 162, so that the lean limit is expanded.

  Further, the second communication passage 161bi is offset with respect to the central axis (cylinder axis CA1) of the first sub-combustion chamber 161a, and is inclined with respect to the cylinder radial direction R1 (see FIG. 10) of the first sub-combustion chamber 161a. ing. On the other hand, the spark plug 129 is provided in the vicinity of the central axis (cylinder axis CA1) of the first auxiliary combustion chamber 161a. Therefore, a swirl flow A2 (see FIG. 11) is generated in the first sub-combustion chamber 161a by the flame radiated from the second sub-combustion chamber 161c to the first sub-combustion chamber 161a via the second communication passage 161bi. As a result, the flames B104i, B105i, B106i, and B110i radiated from the second subcombustion chamber 161c to the first subcombustion chamber 161a via the second communication passage 161bi are prevented from colliding with the tip portion 129a of the spark plug 129. The For this reason, the occurrence of hot surface ignition in the vicinity of the tip portion 129a of the spark plug 129 is reduced, so that the engine load can be easily improved.

  (C) In the first embodiment, the second fuel injection valve 27 is provided in the intake port 23. Instead, a second fuel injection valve (not shown) is provided in the main combustion chamber 63. Also good. In this case, the second fuel injection valve provided in the main combustion chamber 63 supplies fuel to the main combustion chamber 63.

<Configuration and Operation of Sub-chamber Internal Combustion Engine According to Second Embodiment of the Present Invention>
The sub-chamber internal combustion engine 200 according to the second embodiment of the present invention will be described with a focus on differences from the sub-chamber internal combustion engine 1 which is the premise of the present invention, with reference to FIGS.

(Schematic configuration of sub-chamber internal combustion engine)
The sub-chamber internal combustion engine 200 includes a sub-combustion chamber 261 instead of the sub-combustion chamber 61. The auxiliary combustion chamber 261 is surrounded by the auxiliary combustion chamber wall 264. Specifically, a sub-combustion chamber wall 261 having a substantially cylindrical shape is disposed in a space formed between the intake port 23 and the exhaust port 24 in the cylinder head 20 to form a sub-combustion chamber 261. Further, a first communication passage 262 that connects the main combustion chamber 63 and the sub-combustion chamber 261 is formed on the bulged hemispherical bottom surface of the sub-combustion chamber wall 264. The first spark plug (first ignition part) 229 is provided so that the tip end portion 229 a protrudes into the auxiliary combustion chamber 261. The second spark plug (second ignition part) 228 is provided such that a tip portion 228 a projects into the sub-combustion chamber 261.

  Other points are the same as those of the sub-chamber internal combustion engine 1 which is the premise of the present invention.

(Schematic operation of sub-chamber internal combustion engine)
This is the same as the sub-chamber internal combustion engine 1 which is the premise of the present invention.

(Detailed configuration of auxiliary combustion chamber)
12 to 14 are enlarged sectional views of the auxiliary combustion chamber 261. FIG. The cross-sectional views shown in FIGS. 12 to 14 are cross-sectional views taken along a plane including the cylinder axis CA1. In addition, the same component as said subchamber internal combustion engine 1 used as a premise is shown with the same number.

  As shown in FIG. 12, the auxiliary combustion chamber 261 is a chamber surrounded by the auxiliary combustion chamber wall 264. The auxiliary combustion chamber 261 has a substantially cylindrical shape with the cylinder axis CA1 as the central axis. Further, the bottom surface of the auxiliary combustion chamber 261 swells in a hemispherical shape. A plurality of first communication passages 262 communicating the main combustion chamber 63 and the sub-combustion chamber 261 are formed on the expanded hemispherical bottom surface of the sub-combustion chamber wall 264. The first communication passage 262 is inclined downward at an acute angle with the cylinder axis CA1 in the direction from the sub-combustion chamber 261 to the main combustion chamber 63. Thereby, a flame can be efficiently radiated from the auxiliary combustion chamber 261 to the main combustion chamber 63.

  On the other hand, the auxiliary combustion chamber 261 is provided with a first spark plug 229 and a second spark plug 228 at a position facing the first communication passage 262 and at an upper position. The first spark plug 229 and the second spark plug 228 are disposed so as to penetrate the auxiliary combustion chamber wall 264 from the upper side to the lower side, and extend in the direction from the upper part of the auxiliary combustion chamber 261 toward the volume center of the auxiliary combustion chamber 261. It extends.

  Further, the tip end portion 228 a of the second spark plug 228 is disposed in the vicinity of the central axis CA 1 of the auxiliary combustion chamber 261 and away from the main combustion chamber 63 inside the auxiliary combustion chamber 261. A tip portion 228 a of the second spark plug 228 protrudes into the auxiliary combustion chamber 261. The second spark plug 228 generates a spark at the tip portion 228 a to ignite the fresh air mixture in the auxiliary combustion chamber 261.

  On the other hand, the tip portion 229a of the first spark plug 229 is disposed in the sub-combustion chamber 261 in the vicinity of the central axis CA1 of the sub-combustion chamber 261 and closer to the main combustion chamber 63 than the tip portion 228a. A tip portion 229 a of the spark plug 229 protrudes into the auxiliary combustion chamber 261. Further, the protrusion member 264c extends in the sub-combustion chamber 261 from a portion near the main combustion chamber 63 of the sub-combustion chamber wall 264 to a position far from the main combustion chamber 63 (in a direction toward the tip portion 229a). The protruding member 264c and the auxiliary combustion chamber wall 264 are electrically connected, and the tip end portion 229a and the protruding member 264c are electrically insulated. The first spark plug 229 ignites a fresh air mixture in the auxiliary combustion chamber 261 by generating a spark between the tip portion 229a and the protruding member 264c.

(Detailed operation of secondary combustion chamber)
In the compression stroke, a part of the homogeneous fresh air mixture in the main combustion chamber 63 is introduced from the main combustion chamber 63 to the sub-combustion chamber 261 via the first communication passage 262. The first spark plug 229 generates a spark to ignite the fresh air mixture. The ignited fresh air-fuel mixture reaches the first communication path 262 as a flame.

  The flame that has reached the first communication path 262 is emitted in a torch shape from the auxiliary combustion chamber 261 to the main combustion chamber 63 via the first communication path 262 as flames B201 and B202 (first flame).

  Here, since the first communication passage 262 is provided on the main combustion chamber 63 side with respect to the tip end portion 229a of the first spark plug 229, the flames B201 and B202 are directed from the sub-combustion chamber 261 to the main combustion chamber 63. Radiated in the direction (diagonally downward in FIG. 12). That is, the flames B201 and B202 are efficiently radiated from the auxiliary combustion chamber 261 to the main combustion chamber 63.

  Further, the tip portion 229a of the first spark plug 229 is located closer to the first communication path 262 than the tip portion 29a of the spark plug 29 (see FIG. 2). For this reason, the first spark plug 229 ignites the fresh air mixture in the auxiliary combustion chamber 261 as compared with the flame generated by the ignition plug 29 (see FIG. 2) igniting the fresh air mixture in the auxiliary combustion chamber 61. The generated flame reaches the first communication passage 262 when the pressure difference between the main combustion chamber 63 and the sub-combustion chamber 261 is small, so that the propulsive force is small. Thereby, the flame B201, B202 has a slower radiation speed than the flames B7, B8. The radiation speed is a speed at which a flame is radiated from the auxiliary combustion chamber 261 to the main combustion chamber 63 via the first communication path 162. As a result, the flames B201 and B202 have a relatively large spread angle when radiated to the main combustion chamber 63. Further, the propagation direction of the flames B201 and B202 is a direction that mainly spreads in the vicinity of the first communication path 262. Thereby, the contact area and contact time of the unburned fuel F201, F202 near the first communication path 262 and the flames B201, B202 are increased, and most of the unburned fuel F201, F202 is the flames B201, B202. Are changed to burned fuels F203 and F204 (see FIG. 13).

The second spark plug 228 ignites the fresh air mixture in the auxiliary combustion chamber 261 at a timing delayed from the ignition timing of the first spark plug 229. The ignited fresh air-fuel mixture reaches the first communication path 262 as a flame. The ignition timing of the second spark plug 228 is preferably the timing before the flame generated by the ignition of the first spark plug 229 reaches the tip portion 228a of the second spark plug 228. First communication path 262 As shown in FIG. 13, the flame that has reached to the main combustion chamber 63 is emitted in the form of a torch from the sub-combustion chamber 261 via the first communication passage 262 as flames B207 and B208 (second flame).

  Here, since the first communication passage 262 is provided on the main combustion chamber 63 side with respect to the tip end portion 228a of the second spark plug 228, the flames B207 and B208 are directed from the auxiliary combustion chamber 261 to the main combustion chamber 63. Radiated in the direction (diagonally downward in FIG. 13). That is, the flames B207 and B208 are efficiently radiated from the auxiliary combustion chamber 261 to the main combustion chamber 63.

  Further, the tip portion 228 a of the second spark plug 228 is located farther from the first communication path 262 than the tip portion 229 a of the spark plug 229. Therefore, the second spark plug 228 is generated by igniting the fresh air mixture in the auxiliary combustion chamber 261 as compared with the flame generated by the first ignition plug 229 igniting the fresh air mixture in the auxiliary combustion chamber 261. Since the flame reaches the first communication path 262 after the pressure difference between the main combustion chamber 63 and the sub-combustion chamber 261 becomes large, the propulsive force is increased. Thereby, the flames B207 and B208 have a higher radiation speed than the flames B201 and B202. The radiation speed is a speed at which a flame is radiated from the auxiliary combustion chamber 261 to the main combustion chamber 63 via the first communication path 262. As a result, the flames B207 and B208 have a sharp shape with a relatively small spread angle when radiated to the main combustion chamber 63, and the propagation direction is mainly away from the vicinity of the first communication path 262. As a result, the contact area and contact time between the burned fuels F203 and F204 in the vicinity of the first communication passage 262 and the flames B207 and B208 are reduced, but most of the unburned fuels F201 and F202 are already burned fuel F203. , F204, the remaining unburned fuel F201, F202 in the vicinity of the first communication passage 262 is reduced.

  The flames B207 and B208 radiated from the auxiliary combustion chamber 261 to the main combustion chamber 63 burn the fresh air mixture in the main combustion chamber 63.

  Next, in the expansion stroke, the new air-fuel mixture in the main combustion chamber 63 burns, so that the pressure in the main combustion chamber 63 rapidly increases. Here, although the main combustion chamber 63 and the sub-combustion chamber 261 are communicated with each other through the first communication passage 262, the pressure in the main combustion chamber 63 is suddenly increased because the pressure in the main combustion chamber 63 is abrupt. Temporarily higher than the pressure.

  For this reason, as shown in FIG. 14, the burned fuels F203 and F204 remaining in the vicinity of the first communication passage 262 flow from the main combustion chamber 63 into the sub-combustion chamber 261 through the first communication passage 262. The burned fuels F203 and F204 that have flowed into the auxiliary combustion chamber 261 are hot-surface ignited in the auxiliary combustion chamber 261 at high temperatures such as the tip portion 228a of the spark plug 228, the tip portion 229a of the spark plug 229, and the inner wall surface 264a. There is little to do. Thereby, the burned fuels F203 and F204 are reduced from being burned without contributing to the combustion in the main combustion chamber 63, and the cooling loss is reduced.

(Characteristics related to sub-chamber internal combustion engine)
(1)
Here, the first spark plug 229 ignites the fresh air mixture introduced from the main combustion chamber 63 to the sub-combustion chamber 261 via the first communication passage 262, and generates flames B201 and B202. The second spark plug 228 ignites the fresh air-fuel mixture introduced from the main combustion chamber 63 to the sub-combustion chamber 261 via the first communication passage 262, and generates flames B207 and B208. Here, since the flames B201 and B202 have a radiation speed slower than that of the flames B207 and B208, the spread angle when emitted to the main combustion chamber 63 tends to be large. For this reason, most of the unburned fuels F201 and F202 staying in the vicinity of the first communication passage 262 are burned by the flames B201 and B202 and changed into burned fuels F203 and F204. Further, the flames B207 and B208 are generated after the flames B201 and B202, and the radiation speed thereof is faster than the radiation speeds of the flames B201 and B202. For this reason, the fresh air-fuel mixture in the main combustion chamber 63 is combusted by the flames B207 and B208 in a state where the unburned fuel F201 and F202 hardly stay in the vicinity of the first communication passage 262.

  Thus, when the pressure in the main combustion chamber 63 becomes larger than the pressure in the sub-combustion chamber 261, the unburned fuels F201 and F202 staying in the vicinity of the first communication passage 262 are reduced. The fuels F201 and F202 are prevented from flowing back into the auxiliary combustion chamber 261. For this reason, the cooling loss is reduced.

(2)
Here, the first spark plug 229 is located closer to the first communication path 262 than the second spark plug 228. Accordingly, when the difference between the pressure in the auxiliary combustion chamber 261 and the pressure in the main combustion chamber 63 is small, the flames B201 and B202 reach the vicinity of the first communication path 262. For this reason, since the propulsive force of the flames B201 and B202 is smaller than the propulsive force of the flames B207 and B208, the radiation speed of the flames B201 and B202 is slower than the radiation speed of the flames B207 and B208. Further, after the difference between the pressure in the auxiliary combustion chamber 261 and the pressure in the main combustion chamber 63 becomes large, the flames B207 and B208 are radiated from the auxiliary combustion chamber 261 to the main combustion chamber 63 via the first communication path 262. For this reason, the propulsive force of the flames B207 and B208 is larger than the propulsive force of the flames B201 and B202, so that the radiation speeds of the flames B207 and B208 are faster than those of the flames B201 and B202.

(Modification of the second embodiment)
(A) The first spark plug may be configured to generate a spark at the tip portion instead of generating a spark between the tip portion 229a and the protruding member 264c.

  (B) A laser ignition device (not shown) may be provided in the auxiliary combustion chamber 261 instead of the first spark plug 229 and the second spark plug 228. That is, the laser ignition device can change the focal position to a position corresponding to the tip portion 229a and a position corresponding to the tip portion 228a. In this case, the laser ignition device sets the focal position to a position corresponding to the tip portion 229a at a timing corresponding to the ignition timing of the first spark plug 229. Thereby, a flame similar to the flames B201 and B202 is radiated to the main combustion chamber 63 via the first communication path 262.

  Further, the laser ignition device sets the focal position to a position corresponding to the tip portion 228a at a timing corresponding to the ignition timing of the second spark plug 228. As a result, a flame similar to the flames B207 and B208 is radiated to the main combustion chamber 63 via the first communication path 262.

<Configuration and Operation of Sub-chamber Internal Combustion Engine According to Third Embodiment of the Present Invention>
A sub-chamber internal combustion engine 300 according to a third embodiment of the present invention will be described with a focus on differences from the sub-chamber internal combustion engine 1 as a premise of the present invention with reference to FIGS.

(Schematic configuration of sub-chamber internal combustion engine)
The sub chamber internal combustion engine 300 includes a sub combustion chamber 361 instead of the sub combustion chamber 61. The auxiliary combustion chamber 361 is surrounded by auxiliary combustion chamber walls 364 and 366. Specifically, a substantially cylindrical sub-combustion chamber wall 364 and a substantially spherical sub-combustion chamber wall 366 are disposed in a space formed between the intake port 23 and the exhaust port 24 in the cylinder head 20. A sub-combustion chamber 361 is formed. Further, a first communication passage 362 that connects the main combustion chamber 63 and the sub-combustion chamber 361 is formed on the bulged hemispherical bottom surface of the sub-combustion chamber wall 364. The spark plug 329 is provided so that a tip end portion 329 a protrudes into the auxiliary combustion chamber 361.

  Other points are the same as those of the sub-chamber internal combustion engine 1 which is the premise of the present invention.

(Schematic operation of sub-chamber internal combustion engine)
This is the same as the sub-chamber internal combustion engine 1 which is the premise of the present invention.

(Detailed configuration of auxiliary combustion chamber)
15, 17, 19, and 20 are enlarged cross-sectional views of the auxiliary combustion chamber 361. The cross-sectional views shown in FIGS. 15, 17, 19, and 20 are cross-sectional views taken along a plane that includes the cylinder axis CA1 and the first central axis CA2. The first central axis CA2 is a central axis of a second sub-combustion chamber 361c described later in a direction parallel to the cylinder axis CA1. 16 is a cross-sectional view taken along the line XVI-XVI in FIG. 18 is a cross-sectional view taken along the line XVIII-XVIII in FIG. In addition, the same component as said subchamber internal combustion engine 1 used as a premise is shown with the same number.

  The auxiliary combustion chamber 361 includes a first auxiliary combustion chamber 361a, a second communication passage 361b, and a second auxiliary combustion chamber 361c. The first sub-combustion chamber 361a has a substantially circular cross section perpendicular to the cylinder axis CA1. The first auxiliary combustion chamber 361 a is provided adjacent to the main combustion chamber 63 and is a chamber surrounded by the first auxiliary combustion chamber wall 364. The first sub-combustion chamber 361a has a substantially cylindrical shape with the cylinder axis CA1 as the central axis. A plurality of first communication passages 362 communicating the main combustion chamber 63 and the first sub-combustion chamber 361a are formed on the expanded hemispherical bottom surface of the first sub-combustion chamber wall 364. The first communication path 362 is inclined downward at an acute angle with the cylinder axis CA1 in the direction from the first sub-combustion chamber 361a toward the main combustion chamber 63. Thereby, a flame can be efficiently radiated from the first sub-combustion chamber 361a to the main combustion chamber 63.

  The second sub-combustion chamber 361c is provided at a position farther from the main combustion chamber 63 than the first sub-combustion chamber 361a and adjacent to the first sub-combustion chamber 361a. It is an enclosed room. In the second auxiliary combustion chamber 361c, the central axis in the direction parallel to the cylinder axis CA1 is the first central axis CA2, and the central axis in the direction perpendicular to the plane including the cylinder axis CA1 and the first central axis CA2 is the second. The central axis CA3 has a substantially spherical shape.

  Here, the volume of the second auxiliary combustion chamber 361c is larger than the volume of the first auxiliary combustion chamber 361a. As a result, the volume of the fresh air mixture in the second subcombustion chamber 361c is larger than the volume of the fresh air mixture in the first subcombustion chamber 361a, and thus the propulsive force of the flame generated in the first subcombustion chamber 361a. As compared with the above, the propulsive force of the flame generated in the second auxiliary combustion chamber 361c can be increased.

  The second communication passage 361b is formed by opening the first sub-combustion chamber wall 364 and the second sub-combustion chamber wall 366 so as to penetrate from the first sub-combustion chamber 361a to the second sub-combustion chamber 361c. The second communication passage 361b communicates the first sub-combustion chamber 361a and the second sub-combustion chamber 361c. The second communication passage 361b is offset with respect to the second central axis CA3 of the second sub-combustion chamber 361c and is inclined with respect to the second radial direction R3 (see FIG. 15) of the second sub-combustion chamber 361c. . At the same time, the second communication passage 361b is offset with respect to the first central axis CA2 of the second sub-combustion chamber 361c, and is inclined with respect to the first radial direction R2 (see FIG. 16) of the second sub-combustion chamber 361c. ing. Further, the second communication passage 361b is offset with respect to the central axis (cylinder axis CA1) of the first sub-combustion chamber 361a, and is inclined with respect to the cylinder radial direction R1 (see FIG. 18) of the first sub-combustion chamber 361a. ing. The area of the cross section perpendicular to the flow path direction of the second communication path 361b is substantially equal to the area of the cross section perpendicular to the flow path direction of the first communication path 362.

  On the other hand, the auxiliary combustion chamber 361 is provided with a spark plug 329 from an upper position to a position approaching the first communication path 362. The spark plug 329 is disposed so as to penetrate the first auxiliary combustion chamber wall 364 from above to below. The spark plug 329 extends from the upper part of the first sub-combustion chamber 361a to the vicinity of the center of the volume.

  The tip portion 329a of the spark plug 329 is disposed in the first sub-combustion chamber 361a in the vicinity of the cylinder shaft CA1 and away from the main combustion chamber 63. A tip portion 329a of the spark plug 329 protrudes into the first sub-combustion chamber 361a. The spark plug 329 ignites the fresh air mixture in the first auxiliary combustion chamber 361a by generating a spark at the tip end portion 329a. Accordingly, the spark plug 329 can efficiently ignite and burn the fresh air mixture in the first sub-combustion chamber 361a.

(Detailed operation of secondary combustion chamber)
In the compression stroke, a part of the homogeneous fresh air mixture in the main combustion chamber 63 is introduced from the main combustion chamber 63 to the first sub-combustion chamber 361a via the first communication passage 362. Then, the spark plug 329 generates a spark and ignites the fresh air-fuel mixture. The ignited fresh air-fuel mixture reaches not only the first communication path 362 but also the second communication path 361b as a flame.

  The flame that has reached the first communication passage 362 is emitted as a flame B301, B302 (first flame) from the first auxiliary combustion chamber 361a to the main combustion chamber 63 via the first communication passage 362. Here, since the first communication passage 362 is provided on the main combustion chamber 63 side with respect to the tip portion 329a of the spark plug 329, the flames B301 and B302 are directed from the first sub-combustion chamber 361a to the main combustion chamber 63. Radiated in the direction (diagonally downward in FIG. 15). That is, the flames B301 and B302 are efficiently radiated from the first sub-combustion chamber 361a to the main combustion chamber 63.

  Further, the flame that has reached the second communication passage 361b is emitted as a flame B303 from the first auxiliary combustion chamber 361a to the second auxiliary combustion chamber 361c via the second communication passage 361b. Here, since the second communication passage 361b is provided on the side away from the main combustion chamber 63 with respect to the tip portion 329a of the spark plug 329, the flame B303 is directed from the first sub-combustion chamber 361a to the main combustion chamber 63. Radiated in the direction away (left direction in FIG. 15).

  Here, since the volume of the first sub-combustion chamber 361a is smaller than the volume of the second sub-combustion chamber 361c, the volume of the fresh air mixture in the first sub-combustion chamber 361a is the fresh air of the second sub-combustion chamber 361c. It is smaller than the volume of the mixture. Further, since the ignited fresh air-fuel mixture reaches not only the first communication passage 362 but also the second communication passage 361b as a flame, the ignited fresh air-fuel mixture reaches only the first communication passage 62 as a flame. Compared to the case (see FIG. 2), the propulsive force of the flame reaching the first communication path 362 is smaller. For these reasons, the radiation speed of the flames B301 and B302 is slower than that of the flames B7 and B8. The radiation speed is a speed at which a flame is radiated from the first sub-combustion chamber 361a to the main combustion chamber 63 via the first communication path 362. Therefore, the flames B301 and B302 have a relatively large spread angle when radiated to the main combustion chamber 63. Further, the propagation direction of the flames B301 and B302 is a direction that mainly spreads in the vicinity of the first communication path 362. As a result, the contact area and contact time between the unburned fuels F301 and F302 near the first communication path 362 and the flames B301 and B302 are increased, and most of the unburned fuels F301 and F302 are flames B301 and B302. As shown in FIG. 17, the fuel is burned and changed into burned fuels F303 and F304 (see FIG. 17).

  On the other hand, the fresh air mixture in the second auxiliary combustion chamber 361c is ignited and burned by the flame B303. Here, since the propulsive force of the flame reaching the second communication path 361b is also small, the speed at which the flame B303 is radiated is also slow. For this reason, the flame B303 has a relatively large spread angle when radiated to the second sub-combustion chamber 361c, and its propagation direction is mainly in the direction of spreading near the second communication path 361b. . Thereby, the fresh air mixture in the vicinity of the second communication passage 361b is easily burned by the flame B303. Further, since the volume of the second auxiliary combustion chamber 361c is smaller than the volume of the main combustion chamber 63, the volume of the fresh air mixture in the second auxiliary combustion chamber 361c is equal to the volume of the fresh air mixture in the main combustion chamber 63. It is smaller than that. As a result, even if the speed at which the flame B303 is emitted is slow, the combustion period in the second auxiliary combustion chamber 361c is sufficiently short. Further, the swirling flow A3 (see FIG. 15) flows along the inner wall surface 366a to the second sub-combustion chamber 361c by the flame B303 radiated from the first sub-combustion chamber 361a to the second sub-combustion chamber 361c via the second communication path 361b. , See FIG. 16). For this reason, the combustion period in the second auxiliary combustion chamber 361c is surely shortened. As a result, the pressure in the second auxiliary combustion chamber 361c increases rapidly.

  Further, since the volume of the second sub-combustion chamber 361c is larger than the volume of the first sub-combustion chamber 361a, the volume of the fresh air mixture in the second sub-combustion chamber 361c is equal to the fresh air mixture of the first sub-combustion chamber 361a. It is larger than the qi volume. For this reason, the propulsive force of the flame generated in the second auxiliary combustion chamber 361c is larger than the propulsive force of the flame generated in the first auxiliary combustion chamber 361a.

  As shown in FIG. 17, the combustion gas (flame) in the second sub-combustion chamber 361c is radiated to the first sub-combustion chamber 361a via the second communication path 361b as flame B304. A swirling flow A4 flows along the inner wall surface 364a to the first sub-combustion chamber 361a by the flame B304 radiated from the second sub-combustion chamber 361c to the first sub-combustion chamber 361a via the second communication path 361b (see FIG. 18). Is generated. Thereby, the flame B304 radiated from the second subcombustion chamber 361c to the first subcombustion chamber 361a via the second communication path 361b is prevented from colliding with the tip portion 329a of the spark plug 329.

  Further, the flame B304 reaches the first communication path 362. As shown in FIG. 19, the flame B304 that has reached the first communication path 362 is transferred to the main combustion chamber 63 from the first subcombustion chamber 361a via the first communication path 362 as flames B307 and B308 (second flame). Radiated in a torch shape.

  Here, the flames B307 and B308 are radiated in the direction from the first subcombustion chamber 361a toward the main combustion chamber 63 (downwardly in FIG. 19), so that the flames B307 and B308 are emitted from the first subcombustion chamber 361a. It is efficiently radiated to the main combustion chamber 63.

  In addition, the flames B307 and B308 have a higher radiation speed than the flames B301 and B302. Therefore, the flames B307 and B308 have a sharp shape with a relatively small spread angle when radiated to the main combustion chamber 63, and the propagation direction thereof is mainly the direction away from the vicinity of the first communication path 362. This reduces the contact area and contact time between the burned fuels F303 and F304 in the vicinity of the first communication path 362 and the flames B307 and B308, but most of the unburned fuels F301 and F302 are already burned fuel F303. , F304, the remaining unburned fuel F301, F302 in the vicinity of the first communication path 362 is reduced.

  The flames B307 and B308 radiated from the first auxiliary combustion chamber 361a to the main combustion chamber 63 burn the fresh air mixture in the main combustion chamber 63.

  Next, in the expansion stroke, the new air-fuel mixture in the main combustion chamber 63 burns, so that the pressure in the main combustion chamber 63 rapidly increases. Here, the main combustion chamber 63 and the first sub-combustion chamber 361a communicate with each other through the first communication passage 362. However, since the pressure in the main combustion chamber 63 is suddenly increased, the pressure in the main combustion chamber 63 is the first pressure. The pressure temporarily becomes higher than the pressure in the auxiliary combustion chamber 361a.

  For this reason, as shown in FIG. 20, the burned fuels F303 and F304 remaining in the vicinity of the first communication passage 362 flow from the main combustion chamber 63 into the first sub-combustion chamber 361a via the first communication passage 362. . The burned fuels F303 and F304 that have flowed into the first sub-combustion chamber 361a are mostly ignited on the hot surface in the first sub-combustion chamber 361a such as the tip portion 329a of the spark plug 329 and the inner wall surface 364a. Absent. Thereby, it is reduced that the burned fuels F303 and F304 are burned without contributing to the combustion in the main combustion chamber 63, and the cooling loss is reduced.

(Characteristics related to sub-chamber internal combustion engine)
(1)
Here, the spark plug 329 ignites the fresh air mixture introduced from the main combustion chamber 63 to the sub-combustion chamber 361 via the first communication path 362, and generates flames B301 and B302 and flames B307 and B308. . Here, since the flames B301 and B302 have a radiation speed slower than that of the flames B307 and B308, the spread angle when radiated to the main combustion chamber 63 tends to be large. For this reason, most of the unburned fuels F301 and F302 staying in the vicinity of the first communication path 362 are burned by the flames B301 and B302 and changed into burned fuels F303 and F304. The flames B307 and B308 are generated after the flames B301 and B302, and the radiation speed thereof is faster than the radiation speeds of the flames B301 and B302. For this reason, the fresh air-fuel mixture in the main combustion chamber 63 is combusted by the flames B307 and B308 in a state where the unburned fuel F301 and F302 hardly stay in the vicinity of the first communication path 362.

  As described above, when the pressure in the main combustion chamber 63 becomes larger than the pressure in the sub-combustion chamber 361, the unburned fuel F301 and F302 staying in the vicinity of the first communication passage 362 is reduced. The fuels F301 and F302 are prevented from flowing back to the first auxiliary combustion chamber 361a. For this reason, the cooling loss is reduced.

(2)
Here, since the volume of the first sub-combustion chamber 361a is smaller than the volume of the second sub-combustion chamber 361c, the volume of the fresh air mixture in the first sub-combustion chamber 361a is the fresh air of the second sub-combustion chamber 361c. It is smaller than the volume of the mixture. The spark plug 329 is provided in the first sub-combustion chamber 361a. As a result, the flame generated by the spark plug 329 igniting the fresh air mixture in the first auxiliary combustion chamber 361a is dispersed in the first communication path 362 and the second communication path 361b, so that the radiation of the flames B301 and B302 is emitted. The speed decreases, and the flames B301 and B302 reach the vicinity of the first communication path 362. For this reason, the unburned fuels F301 and F302 staying in the vicinity of the first communication path 362 are combusted by the flames B301 and B302.

  The flame B303 radiated from the first subcombustion chamber 361a to the second subcombustion chamber 361c via the second communication path 361b ignites the fresh air mixture in the second subcombustion chamber 361c. Here, the volume of the fresh air mixture in the second auxiliary combustion chamber 361c is larger than the volume of the fresh air mixture in the first auxiliary combustion chamber 361a. For this reason, the propulsive force of the flame generated in the second auxiliary combustion chamber 361c is larger than the propulsive force of the flame generated in the first auxiliary combustion chamber 361a. As a result, flames B307 and B308 having a higher radiation speed than the flames B301 and B302 are radiated from the auxiliary combustion chamber 361 to the main combustion chamber 63 via the first communication path 362. That is, the radiation speeds of the flames B307 and B308 are faster than the radiation speeds of the flames B301 and B302.

(3)
Here, the second communication passage 361b is offset with respect to the second central axis CA3 of the second sub-combustion chamber 361c, and is inclined with respect to the second radial direction R3 (see FIG. 15) of the second sub-combustion chamber 361c. ing. At the same time, the second communication passage 361b is offset with respect to the first central axis CA2 of the second sub-combustion chamber 361c, and is inclined with respect to the first radial direction R2 (see FIG. 16) of the second sub-combustion chamber 361c. ing. Therefore, the swirl flow A3 (see FIGS. 15 and 16) is generated in the second subcombustion chamber 361c by the flame B303 radiated from the first subcombustion chamber 361a to the second subcombustion chamber 361c via the second communication path 361b. Generated. As a result, the combustion period in the second sub-combustion chamber 361c is shortened, and the pressure in the second sub-combustion chamber 361c increases more rapidly. As a result, flames B307 and B308 with higher radiating speed are radiated from the first subcombustion chamber 361a to the main combustion chamber 63 via the first communication passage 362, so that the lean limit is expanded.

(4)
Here, the second communication passage 361b is offset with respect to the central axis (cylinder axis CA1) of the first sub-combustion chamber 361a and is inclined with respect to the cylinder radial direction R1 (see FIG. 18) of the first sub-combustion chamber 361a. is doing. On the other hand, the spark plug 329 is provided in the vicinity of the central axis (cylinder axis CA1) of the first auxiliary combustion chamber 361a. Therefore, a swirl flow A4 (see FIG. 18) is generated in the first sub-combustion chamber 361a by the flame radiated from the second sub-combustion chamber 361c to the first sub-combustion chamber 361a via the second communication path 361b. Thereby, the flame B304 radiated from the second subcombustion chamber 361c to the first subcombustion chamber 361a via the second communication path 361b is prevented from colliding with the tip portion 329a of the spark plug 329. For this reason, the occurrence of hot surface ignition near the tip portion 329a of the spark plug 329 is reduced, so that the engine load can be easily improved.

(5)
Here, the area of the cross section perpendicular to the flow path direction of the second communication path 361b is substantially equal to the area of the cross section perpendicular to the flow path direction of the first communication path 362. For this reason, when the combustion gas (flame) in the first sub-combustion chamber 361a reaches the first communication path 362 and the second communication path 361b, the flames B301, B302, and B303 are stably emitted. Further, the flame B303 causes the fresh air-fuel mixture in the second auxiliary combustion chamber 361c to combust in a stable state with little cycle fluctuation.

<Configuration and Operation of Sub-chamber Internal Combustion Engine According to Fourth Embodiment of the Present Invention>
A sub-chamber internal combustion engine 400 according to a fourth embodiment of the present invention will be described with a focus on differences from the sub-chamber internal combustion engine 1 which is a premise of the present invention, with reference to FIGS.

(Schematic configuration of sub-chamber internal combustion engine)
The sub-chamber internal combustion engine 400 includes a sub-combustion chamber 461 instead of the sub-combustion chamber 61. The auxiliary combustion chamber 461 is surrounded by auxiliary combustion chamber walls 464 and 466. Specifically, a substantially cylindrical auxiliary combustion chamber wall 464 and a substantially cylindrical auxiliary combustion chamber wall 466 are disposed in a space formed between the intake port 23 and the exhaust port 24 in the cylinder head 20. A secondary combustion chamber 461 is formed. In addition, a first communication passage 462 that connects the main combustion chamber 63 and the sub-combustion chamber 461 is formed on the bulged hemispherical bottom surface of the sub-combustion chamber wall 464. The spark plug 429 is provided so that a tip end portion 429 a thereof protrudes into the auxiliary combustion chamber 461.

  Other points are the same as those of the sub-chamber internal combustion engine 1 which is the premise of the present invention.

(Schematic operation of sub-chamber internal combustion engine)
This is the same as the sub-chamber internal combustion engine 1 which is the premise of the present invention.

(Detailed configuration of auxiliary combustion chamber)
21, 23, 25, and 26 are enlarged sectional views of the auxiliary combustion chamber 461. The cross-sectional views shown in FIGS. 21, 23, 25, and 26 are cross-sectional views taken along a plane that includes the cylinder axis CA1 and the third central axis CA4. The third central axis CA4 is a central axis of a second sub-combustion chamber 461c described later in a direction parallel to the cylinder axis CA1. 22 is a cross-sectional view taken along the line XXII-XXII in FIG. 24 is a cross-sectional view taken along the line XXIV-XXIV in FIG. In addition, the same component as said subchamber internal combustion engine 1 used as a premise is shown with the same number.

  The auxiliary combustion chamber 461 includes a first auxiliary combustion chamber 461a, a second communication passage 461b, and a second auxiliary combustion chamber 461c. The first sub-combustion chamber 461a has a substantially circular cross section perpendicular to the cylinder axis CA1. The first auxiliary combustion chamber 461 a is provided adjacent to the main combustion chamber 63 and is a chamber surrounded by the first auxiliary combustion chamber wall 464. The first sub-combustion chamber 461a has a substantially cylindrical shape with the cylinder axis CA1 as the central axis. A plurality of first communication passages 462 communicating the main combustion chamber 63 and the first sub-combustion chamber 461a are formed on the expanded hemispherical bottom surface of the first sub-combustion chamber wall 464. The first communication passage 462 is inclined downward at an acute angle with the cylinder axis CA1 in the direction from the first sub-combustion chamber 461a to the main combustion chamber 63. Thereby, a flame can be efficiently radiated from the first sub-combustion chamber 461a to the main combustion chamber 63.

  The second sub-combustion chamber 461c is provided at a position farther from the main combustion chamber 63 than the first sub-combustion chamber 461a and adjacent to the first sub-combustion chamber 461a. It is an enclosed room. The second sub-combustion chamber 461c has a substantially cylindrical shape with the third central axis CA4 as the central axis.

  Here, the volume of the second auxiliary combustion chamber 461c is larger than the volume of the first auxiliary combustion chamber 461a. As a result, the volume of the fresh air mixture in the second subcombustion chamber 461c is larger than the volume of the fresh air mixture in the first subcombustion chamber 461a, and thus the propulsive force of the flame generated in the first subcombustion chamber 461a. As compared with the above, the propulsive force of the flame generated in the second auxiliary combustion chamber 461c can be increased.

  The second communication passage 461b is formed by opening the first sub-combustion chamber wall 464 and the second sub-combustion chamber wall 466 so as to penetrate from the first sub-combustion chamber 461a to the second sub-combustion chamber 461c. The second communication passage 461b communicates the first sub-combustion chamber 461a and the second sub-combustion chamber 461c. The second communication passage 461b is offset with respect to the third central axis CA4 of the second auxiliary combustion chamber 461c, and is inclined with respect to the third radial direction R4 (see FIG. 22) of the second auxiliary combustion chamber 461c. . The second communication passage 461b is offset with respect to the central axis (cylinder axis CA1) of the first sub-combustion chamber 461a, and is inclined with respect to the cylinder radial direction R1 (see FIG. 24) of the first sub-combustion chamber 461a. ing. The area of the cross section perpendicular to the flow path direction of the second communication path 461b is substantially equal to the area of the cross section perpendicular to the flow path direction of the first communication path 462.

  On the other hand, the auxiliary combustion chamber 461 is provided with a spark plug 429 from an upper position to a position approaching the first communication path 462. The spark plug 429 is disposed so as to penetrate the first sub-combustion chamber wall 464 from above to below. The spark plug 429 extends from the upper part of the first sub-combustion chamber 461a to the vicinity of the center of the volume.

  Further, the tip end portion 429a of the spark plug 429 is disposed in the first sub-combustion chamber 461a in the vicinity of the cylinder axis CA1 and away from the main combustion chamber 63. A tip portion 429a of the spark plug 429 protrudes into the first auxiliary combustion chamber 461a. The spark plug 429 ignites the fresh air-fuel mixture in the first auxiliary combustion chamber 461a by generating a spark at the tip portion 429a. As a result, the spark plug 429 can efficiently ignite and burn the fresh air mixture in the first auxiliary combustion chamber 461a.

(Detailed operation of secondary combustion chamber)
In the compression stroke, a part of the homogeneous fresh air mixture in the main combustion chamber 63 is introduced from the main combustion chamber 63 to the first sub-combustion chamber 461a through the first communication passage 462. Then, the spark plug 429 generates a spark to ignite the fresh air mixture. The ignited fresh air-fuel mixture reaches not only the first communication path 462 but also the second communication path 461b as a flame.

  The flame that has reached the first communication passage 462 is emitted as a flame B401, B402 (first flame) from the first auxiliary combustion chamber 461a to the main combustion chamber 63 via the first communication passage 462. Here, since the first communication passage 462 is provided on the main combustion chamber 63 side with respect to the tip end portion 429a of the spark plug 429, the flames B401 and B402 are directed from the first auxiliary combustion chamber 461a to the main combustion chamber 63. Radiated in the direction (diagonally downward in FIG. 21). That is, the flames B401 and B402 are efficiently radiated from the first sub-combustion chamber 461a to the main combustion chamber 63.

  The flame that has reached the second communication passage 461b is emitted as a torch in the form of flame B403 from the first sub-combustion chamber 461a to the second sub-combustion chamber 461c via the second communication passage 461b. Here, since the second communication passage 461b is provided on the side away from the main combustion chamber 63 with respect to the tip portion 429a of the spark plug 429, the flame B403 is directed from the first sub-combustion chamber 461a to the main combustion chamber 63. Radiated in the direction away (upwardly in the left direction in FIG. 21).

  Here, since the volume of the first auxiliary combustion chamber 461a is smaller than the volume of the second auxiliary combustion chamber 461c, the volume of the fresh air mixture in the first auxiliary combustion chamber 461a is the fresh air of the second auxiliary combustion chamber 461c. It is smaller than the volume of the mixture. Further, since the ignited fresh air-fuel mixture reaches not only the first communication passage 462 but also the second communication passage 461b as a flame, the ignited fresh air-fuel mixture reaches only the first communication passage 62 as a flame. Compared to the case (see FIG. 2), the propulsive force of the flame reaching the first communication path 462 is smaller. For these reasons, the radiation speeds of the flames B401 and B402 are slower than those of the flames B7 and B8. The radiation speed is a speed at which a flame is radiated from the first sub-combustion chamber 461a to the main combustion chamber 63 via the first communication path 462. For this reason, the flames B401 and B402 have a relatively large spread angle when radiated to the main combustion chamber 63. Further, the propagation direction of the flames B401 and B402 is a direction that mainly spreads in the vicinity of the first communication path 462. As a result, the contact area and contact time between the unburned fuels F401 and F402 in the vicinity of the first communication passage 462 and the flames B401 and B402 are increased, and most of the unburned fuels F401 and F402 are flames B401 and B402. Is changed to burned fuels F403 and F404 (see FIG. 23).

  On the other hand, the fresh air mixture in the second auxiliary combustion chamber 461c is ignited and burned by the flame B403. Here, since the propulsive force of the flame reaching the second communication path 461b is also small, the speed at which the flame B403 is emitted is also slow. For this reason, the flame B403 has a relatively large spread angle when radiated to the second sub-combustion chamber 461c, and its propagation direction is mainly in the direction of spreading near the second communication passage 461b. . Thereby, the fresh air mixture in the vicinity of the second communication passage 461b is easily burned by the flame B403. Further, since the volume of the second auxiliary combustion chamber 461c is smaller than the volume of the main combustion chamber 63, the volume of the fresh air mixture in the second auxiliary combustion chamber 461c is equal to the volume of the fresh air mixture in the main combustion chamber 63. It is smaller than that. As a result, even if the speed at which the flame B403 is emitted is slow, the combustion period in the second auxiliary combustion chamber 461c is sufficiently short. Further, the swirling flow A5 (FIG. 22) flows along the inner wall surface 466a to the second sub-combustion chamber 461c by the flame B403 radiated from the first sub-combustion chamber 461a to the second sub-combustion chamber 461c via the second communication passage 461b. Reference) is generated. For this reason, the combustion period in the second auxiliary combustion chamber 461c is reliably shortened. As a result, the pressure in the second auxiliary combustion chamber 461c increases rapidly.

  Further, since the volume of the second sub-combustion chamber 461c is larger than the volume of the first sub-combustion chamber 461a, the volume of the fresh air mixture in the second sub-combustion chamber 461c is equal to the fresh air mixture in the first sub-combustion chamber 461a. It is larger than the qi volume. For this reason, the propulsive force of the flame generated in the second sub-combustion chamber 461c is larger than the propulsive force of the flame generated in the first sub-combustion chamber 461a.

  And as shown in FIG. 23, the combustion gas (flame) of the 2nd subcombustion chamber 461c is radiated | emitted to the 1st subcombustion chamber 461a via the 2nd communicating path 461b as flame B404. The swirl flow A6 to the first sub-combustion chamber 461a along the inner wall surface 464a by the flame B404 radiated from the second sub-combustion chamber 461c to the first sub-combustion chamber 461a via the second communication passage 461b (see FIG. 24). Is generated. Thus, the flame B404 radiated from the second subcombustion chamber 461c to the first subcombustion chamber 461a via the second communication passage 461b is prevented from colliding with the tip portion 429a of the spark plug 429.

  Further, the flame B 404 reaches the first communication path 462. As shown in FIG. 25, the flame B404 that has reached the first communication path 462 is transferred to the main combustion chamber 63 via the first communication path 462 from the first subcombustion chamber 461a as flames B407 and B408 (second flame). Radiated in a torch shape.

  Here, since the flames B407 and B408 are radiated in the direction from the first subcombustion chamber 461a toward the main combustion chamber 63 (the obliquely downward direction in FIG. 25), the flames B407 and B408 are emitted from the first subcombustion chamber 461a. It is efficiently radiated to the main combustion chamber 63.

  Also, the flames B407 and B408 have a higher radiation speed than the flames B401 and B402. For this reason, the flames B407 and B408 have a sharp shape with a relatively small spread angle when radiated to the main combustion chamber 63, and the propagation direction is mainly away from the vicinity of the first communication passage 462. This reduces the contact area and contact time between the burned fuels F403 and F404 in the vicinity of the first communication passage 462 and the flames B407 and B408, but most of the unburned fuels F401 and F402 are already burned fuel F403. , F404, the remaining unburned fuel F401, F402 in the vicinity of the first communication path 462 is reduced.

  The flames B407 and B408 radiated from the first auxiliary combustion chamber 461a to the main combustion chamber 63 burn the fresh air mixture in the main combustion chamber 63.

  Next, in the expansion stroke, the new air-fuel mixture in the main combustion chamber 63 burns, so that the pressure in the main combustion chamber 63 rapidly increases. Here, the main combustion chamber 63 and the first sub-combustion chamber 461a communicate with each other through the first communication passage 462. However, since the pressure in the main combustion chamber 63 increases rapidly, the pressure in the main combustion chamber 63 is the first pressure. It temporarily becomes higher than the pressure in the auxiliary combustion chamber 461a.

  Therefore, as shown in FIG. 26, the burnt fuels F403 and F404 remaining in the vicinity of the first communication passage 462 flow from the main combustion chamber 63 into the first sub-combustion chamber 461a via the first communication passage 462. . The burnt fuels F403 and F404 that have flowed into the first sub-combustion chamber 461a are mostly ignited on the hot surface in the first sub-combustion chamber 461a, such as the tip portion 429a of the spark plug 429 and the inner wall surface 464a. Absent. Thereby, it is reduced that the burned fuel F403, F404 is burned without contributing to the combustion in the main combustion chamber 63, and the cooling loss is reduced.

(Characteristics related to sub-chamber internal combustion engine)
(1)
Here, the spark plug 429 ignites the fresh air mixture introduced from the main combustion chamber 63 to the sub-combustion chamber 461 via the first communication passage 462, and generates flames B401 and B402 and flames B407 and B408. . Here, since the flames B401 and B402 have a radiation speed slower than that of the flames B407 and B408, the spread angle when radiated to the main combustion chamber 63 tends to increase. For this reason, most of the unburned fuels F401 and F402 staying in the vicinity of the first communication passage 462 are burned by the flames B401 and B402 and changed into burned fuels F403 and F404. Further, the flames B407 and B408 are generated after the flames B401 and B402, and the radiation speed thereof is faster than that of the flames B401 and B402. For this reason, the fresh air-fuel mixture in the main combustion chamber 63 is combusted by the flames B407 and B408 in a state where the unburned fuels F401 and F402 are hardly staying in the vicinity of the first communication passage 462.

  Thus, when the pressure in the main combustion chamber 63 becomes larger than the pressure in the sub-combustion chamber 461, the unburned fuels F401 and F402 staying in the vicinity of the first communication passage 462 are reduced. It is suppressed that the fuels F401 and F402 flow back to the first auxiliary combustion chamber 461a. For this reason, the cooling loss is reduced.

(2)
Here, since the volume of the first sub-combustion chamber 461a is smaller than the volume of the second sub-combustion chamber 461c, the volume of the fresh air mixture in the first sub-combustion chamber 461a is the fresh air of the second sub-combustion chamber 461c. It is smaller than the volume of the mixture. The spark plug 429 is provided in the first auxiliary combustion chamber 461a. As a result, the flame generated by the spark plug 429 igniting the fresh air mixture in the first sub-combustion chamber 461a is dispersed in the first communication path 462 and the second communication path 461b, so that the radiation speeds of the flames B401 and B402 And the flames B401 and B402 reach the vicinity of the first communication path 462. For this reason, the unburned fuel F401 and F402 staying in the vicinity of the first communication passage 462 is burned by the flames B401 and B402.

  The flame B403 radiated from the first subcombustion chamber 461a to the second subcombustion chamber 461c via the second communication passage 461b ignites the fresh air mixture in the second subcombustion chamber 461c. Here, the volume of the fresh air mixture in the second auxiliary combustion chamber 461c is larger than the volume of the fresh air mixture in the first auxiliary combustion chamber 461a. For this reason, the propulsive force of the flame generated in the second sub-combustion chamber 461c is larger than the propulsive force of the flame generated in the first sub-combustion chamber 461a. As a result, flames B407 and B408 having a higher radiation speed than the flames B401 and B402 are radiated from the auxiliary combustion chamber 461 to the main combustion chamber 63 via the first communication passage 462. That is, the radiation speeds of the flames B407 and B408 are faster than those of the flames B401 and B402.

(3)
Here, the second communication passage 461b is offset with respect to the third central axis CA4 of the second auxiliary combustion chamber 461c, and is inclined with respect to the third radial direction R4 (see FIG. 22) of the second auxiliary combustion chamber 461c. ing. Therefore, a swirl flow A5 (see FIG. 22) is generated in the second sub-combustion chamber 461c by the flame B403 radiated from the first sub-combustion chamber 461a to the second sub-combustion chamber 461c via the second communication path 461b. . As a result, the combustion period in the second sub-combustion chamber 461c is shortened, and the pressure in the second sub-combustion chamber 461c increases more rapidly. As a result, the flames B407 and B408 having higher radiating speed are radiated from the first auxiliary combustion chamber 461a to the main combustion chamber 63 via the first communication passage 462, so that the lean limit is expanded.

(4)
Here, the second communication passage 461b is offset with respect to the central axis (cylinder axis CA1) of the first sub-combustion chamber 461a, and is inclined with respect to the cylinder radial direction R1 (see FIG. 24) of the first sub-combustion chamber 461a. is doing. On the other hand, the spark plug 429 is provided in the vicinity of the central axis (cylinder axis CA1) of the first auxiliary combustion chamber 461a. Therefore, a swirl flow A6 (see FIG. 24) is generated in the first sub-combustion chamber 461a by the flame radiated from the second sub-combustion chamber 461c to the first sub-combustion chamber 461a via the second communication passage 461b. Thus, the flame B404 radiated from the second subcombustion chamber 461c to the first subcombustion chamber 461a via the second communication passage 461b is prevented from colliding with the tip portion 429a of the spark plug 429. For this reason, the occurrence of hot surface ignition near the tip portion 429a of the spark plug 429 is reduced, so that the engine load can be easily improved.

(5)
Here, the area of the cross section perpendicular to the flow path direction of the second communication path 461b is substantially equal to the area of the cross section perpendicular to the flow path direction of the first communication path 462. For this reason, when the combustion gas (flame) in the first sub-combustion chamber 461a reaches the first communication path 462 and the second communication path 461b, the flames B401, B402, B403 are stably emitted. Further, the flame B403 causes the fresh air mixture in the second auxiliary combustion chamber 461c to combust in a stable state with little cycle fluctuation.

(Modification of the fourth embodiment)
As shown in FIG. 27, in the auxiliary combustion chamber 461i of the auxiliary chamber internal combustion engine 400i, the second auxiliary combustion chamber 461ci may further be provided with a first fuel injection valve 425i. At this time, the first fuel injection valve 425i is disposed so as to penetrate the second auxiliary combustion chamber wall 466 from above to below. The first fuel injection valve 425i injects fuel into the second auxiliary combustion chamber 461ci.

  As a result, the combustion in the second sub-combustion chamber 461ci is promoted, so that the pressure in the second sub-combustion chamber 461ci further increases abruptly. As a result, flames B407i and B408i with higher radiating speed are radiated from the first auxiliary combustion chamber 461a to the main combustion chamber 63 via the first communication path 462.

  In addition to the fuel (fresh air mixture) introduced from the first sub-combustion chamber 461a to the second sub-combustion chamber 461ci via the second communication passage 461b, fuel is further supplied to the second sub-combustion chamber 461ci. Therefore, the air-fuel ratio of the second sub-combustion chamber 461ci can be made closer to the stoichiometric air-fuel ratio than the air-fuel ratio of the first sub-combustion chamber 461a. For this reason, the pressure in the second sub-combustion chamber 461ci can be increased more rapidly.

<Configuration and Operation of Sub-chamber Internal Combustion Engine According to Fifth Embodiment of the Present Invention>
A sub-chamber internal combustion engine 500 according to a fifth embodiment of the present invention will be described with a focus on differences from the sub-chamber internal combustion engine 1 which is the premise of the present invention, with reference to FIGS.

(Schematic configuration of sub-chamber internal combustion engine)
The sub chamber internal combustion engine 500 includes a sub combustion chamber 561 instead of the sub combustion chamber 61. The auxiliary combustion chamber 561 is surrounded by auxiliary combustion chamber walls 564, 566, and 567. Specifically, in the space formed between the intake port 23 and the exhaust port 24 in the cylinder head 20, a substantially cylindrical sub-combustion chamber wall 564, a substantially cylindrical sub-combustion chamber wall 566, and a substantially cylindrical shape are provided. A secondary combustion chamber wall 567 having a shape is arranged to form a secondary combustion chamber 561. Further, a first communication passage 562 that connects the main combustion chamber 63 and the sub-combustion chamber 561 is formed on the bulged hemispherical bottom surface of the sub-combustion chamber wall 564. The spark plug 529 is provided so that a tip end portion 529 a thereof protrudes into the auxiliary combustion chamber 561.

  Other points are the same as those of the sub-chamber internal combustion engine 1 which is the premise of the present invention.

(Schematic operation of sub-chamber internal combustion engine)
This is the same as the sub-chamber internal combustion engine 1 which is the premise of the present invention.

(Detailed configuration of auxiliary combustion chamber)
28, 30, 32, and 33 are enlarged sectional views of the auxiliary combustion chamber 561. 28, 30, 32, and 33 are cross-sectional views taken along a plane that includes the cylinder axis CA1, the fourth central axis CA5, and the fifth central axis CA6. The fourth central axis CA5 is a central axis of a second sub-combustion chamber 561c described later in a direction parallel to the cylinder axis CA1. The fifth central axis CA6 is a central axis of a second sub-combustion chamber 561f described later in a direction parallel to the cylinder axis CA1. 29 is a cross-sectional view taken along the line XXIX-XXIX in FIG. 31 is a cross-sectional view taken along XXXI-XXXI in FIG. In addition, the same component as said subchamber internal combustion engine 1 used as a premise is shown with the same number.

  The auxiliary combustion chamber 561 includes a first auxiliary combustion chamber 561a, a plurality of second communication passages 561b and 561e, and a plurality of second auxiliary combustion chambers 561c and 561f. The first sub-combustion chamber 561a has a substantially circular cross section perpendicular to the cylinder axis CA1. The first auxiliary combustion chamber 561 a is provided adjacent to the main combustion chamber 63 and is a chamber surrounded by the first auxiliary combustion chamber wall 564. The first sub-combustion chamber 561a has a substantially cylindrical shape with the cylinder axis CA1 as the central axis. A plurality of first communication passages 562 communicating the main combustion chamber 63 and the first sub-combustion chamber 561a are formed on the expanded hemispherical bottom surface of the first sub-combustion chamber wall 564. The first communication passage 562 is inclined downward at an acute angle with the cylinder axis CA1 in the direction from the first sub-combustion chamber 561a toward the main combustion chamber 63. Thereby, a flame can be efficiently radiated from the first sub-combustion chamber 561a to the main combustion chamber 63.

  The second sub-combustion chambers 561c and 561f are provided at positions farther from the main combustion chamber 63 than the first sub-combustion chamber 561a and adjacent to the first sub-combustion chamber 561a. It is a room surrounded by 566,567. The second sub-combustion chamber 561c has a substantially cylindrical shape with the central axis in the direction parallel to the cylinder axis CA1 being the fourth central axis CA5. The second sub-combustion chamber 561f has a substantially cylindrical shape in which the central axis in the direction parallel to the cylinder axis CA1 is the fifth central axis CA6.

  Here, the total volume of the second auxiliary combustion chambers 561c and 561f is larger than the volume of the first auxiliary combustion chamber 561a. As a result, the total volume of the fresh air mixture in the second subcombustion chambers 561c and 561f becomes larger than the volume of the fresh air mixture in the first subcombustion chamber 561a, so that the flame generated in the first subcombustion chamber 561a. The total propulsive force of the flames generated in the second sub-combustion chambers 561c and 561f can be made larger than the propulsive force.

  The second communication passage 561b is formed by opening the first sub-combustion chamber wall 564 and the second sub-combustion chamber wall 566 so as to penetrate from the first sub-combustion chamber 561a to the second sub-combustion chamber 561c. The second communication passage 561b communicates the first sub-combustion chamber 561a and the second sub-combustion chamber 561c. The second communication passage 561b is offset with respect to the fourth central axis CA5 of the second auxiliary combustion chamber 561c, and is inclined with respect to the fourth radial direction R5 (see FIG. 29) of the second auxiliary combustion chamber 561c. . Then, the second communication passage 561b is offset with respect to the central axis (cylinder axis CA1) of the first sub-combustion chamber 561a, and is inclined with respect to the cylinder radial direction R1 (see FIG. 31) of the first sub-combustion chamber 561a. ing. The area of the cross section perpendicular to the flow path direction of the second communication path 561b is substantially equal to the area of the cross section perpendicular to the flow path direction of the first communication path 562.

  The second communication passage 561e is formed by opening the first sub-combustion chamber wall 564 and the second sub-combustion chamber wall 567 so as to penetrate from the first sub-combustion chamber 561a to the second sub-combustion chamber 561f. Yes. The second communication passage 561e communicates the first sub-combustion chamber 561a and the second sub-combustion chamber 561f. The second communication passage 561e is offset with respect to the fifth central axis CA6 of the second sub-combustion chamber 561f, and is inclined with respect to the fifth radial direction R6 (see FIG. 29) of the second sub-combustion chamber 561f. . Then, the second communication passage 561e is offset with respect to the central axis (cylinder axis CA1) of the first sub-combustion chamber 561a, and is inclined with respect to the cylinder radial direction R1 (see FIG. 31) of the first sub-combustion chamber 561a. ing. The area of the cross section perpendicular to the flow path direction of the second communication path 561e is substantially equal to the area of the cross section perpendicular to the flow path direction of the first communication path 562.

  On the other hand, the auxiliary combustion chamber 561 is provided with a spark plug 529 from an upper position to a position approaching the first communication path 562. The spark plug 529 is disposed so as to penetrate the first sub-combustion chamber wall 564 from above to below. The spark plug 529 extends from the upper part of the first auxiliary combustion chamber 561a to the vicinity of the center of the volume.

  Further, the tip portion 529a of the spark plug 529 is disposed in the first sub-combustion chamber 561a in the vicinity of the cylinder axis CA1 and away from the main combustion chamber 63. A tip portion 529a of the spark plug 529 protrudes into the first sub-combustion chamber 561a. The spark plug 529 ignites the fresh air mixture in the first sub-combustion chamber 561a by generating a spark at the tip portion 529a. Thus, the spark plug 529 can efficiently ignite and burn the fresh air mixture in the first auxiliary combustion chamber 561a.

(Detailed operation of secondary combustion chamber)
In the compression stroke, a part of the homogeneous fresh air mixture in the main combustion chamber 63 is introduced from the main combustion chamber 63 to the first sub-combustion chamber 561a via the first communication passage 562. The spark plug 529 ignites the fresh air-fuel mixture by generating sparks. The ignited fresh air-fuel mixture reaches not only the first communication path 562 but also the second communication paths 561b and 561e as a flame.

  The flame that has reached the first communication path 562 is emitted as a flame B501, B502 (first flame) from the first auxiliary combustion chamber 561a to the main combustion chamber 63 via the first communication path 562. Here, since the first communication passage 562 is provided on the main combustion chamber 63 side with respect to the tip portion 529a of the spark plug 529, the flames B501 and B502 are directed from the first sub-combustion chamber 561a to the main combustion chamber 63. Radiated in the direction (diagonally downward in FIG. 28). That is, the flames B501 and B502 are efficiently radiated from the first sub-combustion chamber 561a to the main combustion chamber 63.

  The flames that have reached the second communication passages 561b and 561e are in a torch shape as flames B503 and B509 from the first auxiliary combustion chamber 561a to the second auxiliary combustion chambers 561c and 561f via the second communication passages 561b and 561e. Radiated. Here, since the second communication passages 561b and 561e are provided on the side away from the main combustion chamber 63 with respect to the tip portion 529a of the spark plug 529, the flames B503 and B509 are transferred from the first subcombustion chamber 561a to the main combustion chamber. Radiated in a direction away from 63 (an obliquely upward direction in FIG. 28).

  Here, since the volume of the first auxiliary combustion chamber 561a is smaller than the total volume of the second auxiliary combustion chambers 561c, 561f, the volume of the fresh air mixture in the first auxiliary combustion chamber 561a is the second auxiliary combustion chamber 561c. , 561f is smaller than the total volume of the fresh air mixture. Further, since the ignited fresh air-fuel mixture reaches not only the first communication passage 562 but also the second communication passages 561b and 561e as a flame, the ignited fresh air-fuel mixture is only introduced into the first communication passage 62 as a flame. The propulsive force of the flame reaching the first communication path 562 is smaller than that when reaching (see FIG. 2). For these reasons, the flames B501 and B502 have a lower radiation speed than the flames B7 and B8. The radiation speed is a speed at which a flame is radiated from the first sub-combustion chamber 561a to the main combustion chamber 63 via the first communication path 562. Therefore, the flames B501 and B502 have a relatively large spread angle when radiated to the main combustion chamber 63. In addition, the propagation direction of the flames B501 and B502 is a direction mainly spreading in the vicinity of the first communication path 562. Thereby, the contact area and contact time of the unburned fuels F501 and F502 in the vicinity of the first communication passage 562 and the flames B501 and B502 are increased, and most of the unburned fuels F501 and F502 are the flames B501 and B502. Is changed to burned fuels F503 and F504 (see FIG. 30).

  On the other hand, the fresh air mixture in the second auxiliary combustion chambers 561c and 561f is ignited and burned by the flames B503 and B509. Here, since the propulsive force of the flame reaching the second communication passages 561b and 561e is also reduced, the radiating speed of the flames B503 and B509 is also reduced. For this reason, the flames B503 and B509 have a relatively large spread angle when radiated to the second sub-combustion chambers 561c and 561f, and the propagation direction thereof is mainly close to the second communication passages 561b and 561e. It has become a spreading direction. Thereby, the fresh air mixture in the vicinity of the second communication passages 561b and 561e is easily burned by the flames B503 and B509. Further, since the total volume of the second auxiliary combustion chambers 561c and 561f is smaller than the volume of the main combustion chamber 63, the total volume of the fresh air mixture in the second auxiliary combustion chambers 561c and 561f is the new volume of the main combustion chamber 63. It is smaller than the volume of the air-fuel mixture. As a result, even if the radiating speed of the flames B503 and B509 is low, the combustion period in the second auxiliary combustion chambers 561c and 561f is sufficiently short. Further, the swirl flow A7 (FIG. 29) flows along the inner wall surface 566a to the second sub-combustion chamber 561c by the flame B503 radiated from the first sub-combustion chamber 561a to the second sub-combustion chamber 561c via the second communication path 561b. Reference) is generated. Further, the swirl flow A8 (FIG. 29) flows along the inner wall surface 567a to the second auxiliary combustion chamber 561f by the flame B509 radiated from the first auxiliary combustion chamber 561a to the second auxiliary combustion chamber 561f via the second communication passage 561e. Reference) is generated. For this reason, the combustion period in the second sub-combustion chambers 561c and 561f is reliably shortened. As a result, the pressure in the second sub-combustion chambers 561c and 561f rises rapidly.

  Further, since the total volume of the second auxiliary combustion chambers 561c and 561f is larger than the volume of the first auxiliary combustion chamber 561a, the total volume of the fresh air mixture in the second auxiliary combustion chambers 561c and 561f is the first auxiliary combustion chamber. It is larger than the volume of the fresh air mixture in the chamber 561a. For this reason, the total propulsive force of the flame generated in the second auxiliary combustion chambers 561c and 561f is larger than the propulsive force of the flame generated in the first auxiliary combustion chamber 561a.

  As shown in FIG. 30, the combustion gas (flame) in the second sub-combustion chamber 561c is radiated to the first sub-combustion chamber 561a via the second communication passage 561b as flame B504. Further, the combustion gas (flame) in the second sub-combustion chamber 561f is radiated to the first sub-combustion chamber 561a as the flame B510 via the second communication passage 561e. Flame B504 radiated from the second subcombustion chamber 561c to the first subcombustion chamber 561a via the second communication passage 561b, and radiation from the second subcombustion chamber 561f to the first subcombustion chamber 561a via the second communication passage 561e The swirling flow A9 (see FIG. 31) is generated in the first sub-combustion chamber 561a along the inner wall surface 564a by the flame B510. As a result, the flame B504 radiated from the second subcombustion chamber 561c to the first subcombustion chamber 561a via the second communication passage 561b is suppressed from colliding with the tip portion 529a of the spark plug 529, and the second subcombustion chamber It is also suppressed that the flame B510 radiated from 561f to the first auxiliary combustion chamber 561a via the second communication path 561e collides with the tip portion 529a of the spark plug 529.

  Further, the flames B504 and B510 reach the first communication path 562. As shown in FIG. 32, the flames B504 and B510 that have reached the first communication passage 562 are converted into flames B507 and B508 (second flame) from the first auxiliary combustion chamber 561a via the first communication passage 562, as shown in FIG. Radiated in a torch shape.

  Here, since the flames B507 and B508 are radiated in the direction from the first sub-combustion chamber 561a toward the main combustion chamber 63 (diagonally downward in FIG. 32), the flames B507 and B508 are emitted from the first sub-combustion chamber 561a. It is efficiently radiated to the main combustion chamber 63.

  Also, the flames B507 and B508 have a higher radiation speed than the flames B501 and B502. Therefore, the flames B507 and B508 have a sharp shape with a relatively small spread angle when radiated to the main combustion chamber 63, and the propagation direction thereof is mainly the direction away from the vicinity of the first communication path 562. This reduces the contact area and contact time between the burned fuels F503 and F504 in the vicinity of the first communication passage 562 and the flames B507 and B508, but most of the unburned fuels F501 and F502 are already burned fuel F503. , F504, the remaining unburned fuel F501, F502 in the vicinity of the first communication path 562 is reduced.

  The flames B507 and B508 radiated from the first auxiliary combustion chamber 561a to the main combustion chamber 63 burn the fresh air mixture in the main combustion chamber 63.

  Next, in the expansion stroke, the new air-fuel mixture in the main combustion chamber 63 burns, so that the pressure in the main combustion chamber 63 rapidly increases. Here, the main combustion chamber 63 and the first sub-combustion chamber 561a are communicated with each other through the first communication passage 562. However, since the pressure in the main combustion chamber 63 increases rapidly, the pressure in the main combustion chamber 63 is the first pressure. It temporarily becomes higher than the pressure in the auxiliary combustion chamber 561a.

  Therefore, as shown in FIG. 33, the burnt fuels F503 and F504 remaining in the vicinity of the first communication passage 562 flow from the main combustion chamber 63 into the first sub-combustion chamber 561a via the first communication passage 562. . The burned fuels F503 and F504 that have flowed into the first sub-combustion chamber 561a are mostly ignited on the hot surface in the first sub-combustion chamber 561a where the temperature is high, such as the tip portion 529a of the spark plug 529 and the inner wall surface 564a. Absent. Thereby, it is reduced that the burned fuels F503 and F504 are burned without contributing to the combustion in the main combustion chamber 63, and the cooling loss is reduced.

(Characteristics related to sub-chamber internal combustion engine)
(1)
Here, the spark plug 529 ignites the fresh air mixture introduced from the main combustion chamber 63 to the sub-combustion chamber 561 via the first communication passage 562, and generates flames B501, B502 and flames B507, B508. . Here, since the flames B501 and B502 have a radiation speed slower than that of the flames B507 and B508, the spread angle when emitted to the main combustion chamber 63 tends to be large. For this reason, most of the unburned fuels F501 and F502 staying in the vicinity of the first communication passage 562 are burned by the flames B501 and B502 and changed to burned fuels F503 and F504. Moreover, the flames B507 and B508 are generated after the flames B501 and B502, and the radiation speed thereof is faster than the radiation speeds of the flames B501 and B502. For this reason, the fresh air mixture in the main combustion chamber 63 is combusted by the flames B507 and B508 in a state where the unburned fuel F501 and F502 hardly stay in the vicinity of the first communication passage 562.

  Thus, when the pressure in the main combustion chamber 63 becomes larger than the pressure in the sub-combustion chamber 561, the unburned fuels F501 and F502 staying in the vicinity of the first communication passage 562 are reduced. The fuel F501 and F502 are prevented from flowing back to the first auxiliary combustion chamber 561a. For this reason, the cooling loss is reduced.

(2)
Here, since the volume of the first auxiliary combustion chamber 561a is smaller than the total volume of the second auxiliary combustion chambers 561c, 561f, the volume of the fresh air mixture in the first auxiliary combustion chamber 561a is the second auxiliary combustion chamber 561c. , 561f is smaller than the total volume of the fresh air mixture. The spark plug 529 is provided in the first sub-combustion chamber 561a. As a result, the flame generated by the spark plug 529 igniting the fresh air mixture in the first auxiliary combustion chamber 561a is dispersed in the first communication path 562 and the second communication paths 561b and 561e. The radiation speed becomes slow, and the flames B501 and B502 reach the vicinity of the first communication path 562. For this reason, the unburnt fuels F501 and F502 staying in the vicinity of the first communication path 562 are burned by the flames B501 and B502.

  Flames B503 and B509 radiated from the first auxiliary combustion chamber 561a to the second auxiliary combustion chambers 561c and 561f via the second communication passages 561b and 561e ignite the fresh air mixture in the second auxiliary combustion chambers 561c and 561f. To do. Here, the volume of the fresh air mixture in the second auxiliary combustion chambers 561c and 561f is larger than the volume of the fresh air mixture in the first auxiliary combustion chamber 561a. For this reason, the propulsive force of the flame generated in the second sub-combustion chambers 561c and 561f is larger than the propulsive force of the flame generated in the first sub-combustion chamber 561a. As a result, flames B507 and B508 having a higher radiation speed than the flames B501 and B502 are radiated from the auxiliary combustion chamber 561 to the main combustion chamber 63 via the first communication path 562. That is, the radiation speeds of the flames B507 and B508 are faster than the radiation speeds of the flames B501 and B502.

(3)
Here, the second communication passage 561b is offset with respect to the fourth central axis CA5 of the second auxiliary combustion chamber 561c, and is inclined with respect to the fourth radial direction R5 (see FIG. 29) of the second auxiliary combustion chamber 561c. ing. Therefore, a swirl flow A7 (see FIG. 29) is generated in the second sub-combustion chamber 561c by the flame B503 radiated from the first sub-combustion chamber 561a to the second sub-combustion chamber 561c via the second communication path 561b. .

  Further, the second communication passage 561e is offset with respect to the fifth central axis CA6 of the second auxiliary combustion chamber 561f, and is inclined with respect to the fifth radial direction R6 (see FIG. 29) of the second auxiliary combustion chamber 561f. Yes. Therefore, a swirl flow A8 (see FIG. 29) is generated in the second sub-combustion chamber 561f by the flame B509 radiated from the first sub-combustion chamber 561a to the second sub-combustion chamber 561f via the second communication path 561e. .

  As a result, the combustion period in the second sub-combustion chambers 561c and 561f is shortened, and the pressure in the second sub-combustion chambers 561c and 561f increases more rapidly. As a result, the flames B507 and B508 having higher radiating speed are radiated from the first sub-combustion chamber 561a to the main combustion chamber 63 via the first communication passage 562, so that the lean limit is expanded.

(4)
Here, the second communication passages 561b and 561e are offset with respect to the central axis (cylinder axis CA1) of the first auxiliary combustion chamber 561a, respectively, and the cylinder radial direction R1 of the first auxiliary combustion chamber 561a (see FIG. 31). It is inclined with respect to. On the other hand, the spark plug 529 is provided in the vicinity of the central axis (cylinder axis CA1) of the first auxiliary combustion chamber 561a. Therefore, a swirl flow A9 (see FIG. 31) is generated in the first sub-combustion chamber 561a by the flame radiated from the second sub-combustion chambers 561c, 561f to the first sub-combustion chamber 561a via the second communication passages 561b, 561e. Generated. As a result, the flames B504 and B510 radiated from the second auxiliary combustion chambers 561c and 561f to the first auxiliary combustion chamber 561a via the second communication passages 561b and 561e are prevented from colliding with the tip portion 529a of the spark plug 529. The For this reason, the occurrence of hot surface ignition near the tip portion 529a of the spark plug 529 is reduced, so that the engine load can be easily improved.

(5)
Here, the area of the cross section perpendicular to the flow path direction of the second communication paths 561b and 561e is substantially equal to the area of the cross section perpendicular to the flow path direction of the first communication path 562. Therefore, when the combustion gas (flame) in the first sub-combustion chamber 561a reaches the first communication path 562 and the second communication paths 561b, 561e, the flames B501, B502, B503, B509 are stably emitted. It will be. In addition, the fresh air-fuel mixture in the second auxiliary combustion chambers 561c and 561f is combusted in a stable state with little cycle fluctuation by the flames B503 and B509.

  The sub-chamber internal combustion engine according to the present invention has an effect of reducing the cooling loss, and is useful as a sub-chamber internal combustion engine or the like.

Sectional drawing of the subchamber internal combustion engine used as a premise. The expanded sectional view of the subcombustion chamber in the subchamber type internal combustion engine used as a premise. The expanded sectional view of the subcombustion chamber in the subchamber type internal combustion engine used as a premise. 1 is a cross-sectional view of a sub-chamber internal combustion engine according to a first embodiment of the present invention. The expanded sectional view of the subcombustion chamber in a 1st embodiment of the present invention. The expanded sectional view of the subcombustion chamber in a 1st embodiment of the present invention. The expanded sectional view of the subcombustion chamber in a 1st embodiment of the present invention. The expanded sectional view of the subcombustion chamber in a 1st embodiment of the present invention. The expanded sectional view of the subcombustion chamber in the modification of a 1st embodiment of the present invention. XX sectional drawing of FIG. The expanded sectional view of the subcombustion chamber in the modification of a 1st embodiment of the present invention. The expanded sectional view of the subcombustion chamber in a 2nd embodiment of the present invention. The expanded sectional view of the subcombustion chamber in a 2nd embodiment of the present invention. The expanded sectional view of the subcombustion chamber in a 2nd embodiment of the present invention. The expanded sectional view of the subcombustion chamber in a 3rd embodiment of the present invention. XVI-XVI sectional drawing of FIG. The expanded sectional view of the subcombustion chamber in a 3rd embodiment of the present invention. XVIII-XVIII sectional drawing of FIG. The expanded sectional view of the subcombustion chamber in a 3rd embodiment of the present invention. The expanded sectional view of the subcombustion chamber in a 3rd embodiment of the present invention. The expanded sectional view of the auxiliary combustion chamber in a 4th embodiment of the present invention. XXII-XXII sectional drawing of FIG. The expanded sectional view of the auxiliary combustion chamber in a 4th embodiment of the present invention. XXIV-XXIV sectional drawing of FIG. The expanded sectional view of the auxiliary combustion chamber in a 4th embodiment of the present invention. The expanded sectional view of the auxiliary combustion chamber in a 4th embodiment of the present invention. The expanded sectional view of the subcombustion chamber in the modification of 4th Embodiment of this invention. The expanded sectional view of the auxiliary combustion chamber in a 5th embodiment of the present invention. XXIX-XXIX sectional drawing of FIG. The expanded sectional view of the auxiliary combustion chamber in a 5th embodiment of the present invention. XXXI-XXXI sectional drawing of FIG. The expanded sectional view of the auxiliary combustion chamber in a 5th embodiment of the present invention. The expanded sectional view of the auxiliary combustion chamber in a 5th embodiment of the present invention.

Explanation of symbols

1,100,100i, 200,300,400,400i, 500 Sub-chamber internal combustion engine 27 Second fuel injection valve (second fuel supply unit)
29,129,329,429,529 Spark plug (ignition part)
61, 161, 161a, 261, 361, 461, 461a, 561 Sub combustion chambers 61a, 161a, 261a, 361a, 461a, 561a First sub combustion chambers 61b, 161b, 161bi, 261b, 361b, 461b, 561b, 561e Two communication passages 61c, 161c, 261c, 361c, 461c, 561c, 561f Second auxiliary combustion chamber 62, 162, 262, 362, 462, 562 First communication passage 63 Main combustion chamber 228 Second spark plug (second ignition portion )
229 First spark plug (first ignition part)
425a First fuel injection valve B101, B201, B301, B401, B501, etc. Flame (first flame)
B107 etc., B207 etc., B307 etc., B407 etc., B507 etc. Flame (second flame)

Claims (7)

A main combustion chamber;
A secondary combustion chamber adjacent to the main combustion chamber;
A first communication passage communicating the main combustion chamber and the sub-combustion chamber;
When the fresh air-fuel mixture introduced from the main combustion chamber to the sub-combustion chamber via the first communication passage is ignited and radiated from the sub-combustion chamber to the main combustion chamber via the first communication passage A first flame having a first peak which is a peak of a radiation speed which is a velocity of the second peak, and a second peak which is a peak after the first peak and which is a peak of the radiation speed which is larger than the first peak. An ignition part for generating a second flame having;
With
Sub-chamber internal combustion engine. The ignition unit is
A first ignition unit for generating the first flame;
A second ignition unit for generating the second flame;
Have
The first ignition unit is located closer to the first communication path than the second ignition unit;
The sub-chamber internal combustion engine according to claim 1. The auxiliary combustion chamber is
A first subcombustion chamber communicated with the main combustion chamber via the first communication passage;
One or more second sub-combustion chambers disposed at a position farther from the main combustion chamber than the first sub-combustion chamber and adjacent to the first sub-combustion chamber;
One or more second communication passages communicating the first sub-combustion chamber and the second sub-combustion chamber;
Have
The total volume of the second auxiliary combustion chamber is larger than the volume of the first auxiliary combustion chamber,
The ignition unit is provided in the first sub-combustion chamber;
The sub-chamber internal combustion engine according to claim 1. The second auxiliary combustion chamber is either a substantially spherical shape or a substantially cylindrical shape,
The second communication path is offset with respect to a central axis of the second sub-combustion chamber and is inclined with respect to a radial direction of the second sub-combustion chamber;
The sub-chamber internal combustion engine according to claim 3. The first sub-combustion chamber is either a substantially spherical shape or a substantially cylindrical shape,
The ignition part is provided in the vicinity of the central axis of the first sub-combustion chamber,
The second communication path is offset with respect to a central axis of the first sub-combustion chamber and is inclined with respect to a radial direction of the first sub-combustion chamber;
The sub-chamber internal combustion engine according to claim 3. A first fuel supply unit for supplying fuel to the second sub-combustion chamber;
The sub-chamber internal combustion engine according to claim 3. A second fuel supply unit for supplying fuel to at least one of the main combustion chamber and the intake port;
The sub-chamber internal combustion engine according to claim 6.

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