JP2006242156A - Indirect injection internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an indirect injection internal combustion engine capable of restricting outbreak of heat surface ignition. <P>SOLUTION: This indirect injection internal combustion engine 1 is provided with a main combustion chamber 63, an auxiliary combustion chamber 61, a first communication passage 62, an ignition plug 29, a pressure chamber 67, a second communication passage 68 and a pressure adjusting mechanism 70. The auxiliary combustion chamber 61 is adjacent to the main combustion chamber 63. The first communication passage 62 communicates the main combustion chamber 63 with the auxiliary combustion chamber 61. A tip part 29a of the ignition plug 29 is provided in the auxiliary combustion chamber 61. The tip part 29a of the ignition plug 29 ignites fresh air-fuel mixture led from the main combustion chamber 63 to the auxiliary combustion chamber 61 through the first communication passage 62. The pressure chamber 67 is arranged at a position far from the main combustion chamber 63 in comparison with the auxiliary combustion chamber 61, and arranged adjacent to the auxiliary combustion chamber 61. The second communication passage 68 communicates the auxiliary combustion chamber 61 with the pressure chamber 67. The pressure adjusting mechanism 70 raises the pressure of the pressure chamber 67 higher than that of the auxiliary combustion chamber 61 in a first cycle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

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-2002-81321 (page 1-3, FIG. 1-15)

  However, in the technique of Patent Document 1, the wall surface of the auxiliary combustion chamber may be heated to a high temperature. Moreover, the ignition part provided in the auxiliary combustion chamber and igniting the fresh air mixture introduced from the main combustion chamber to the auxiliary combustion chamber may be heated to a high temperature. For this reason, hot surface ignition tends to occur.

  The subject of this invention is providing the subchamber internal combustion engine which can suppress generation | occurrence | production of a hot surface ignition.

  The sub-chamber internal combustion engine according to the present invention includes a main combustion chamber, a sub-combustion chamber, a first communication passage, an ignition unit, a pressure chamber, a second communication passage, and a pressure adjustment mechanism. 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 is provided in 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. The pressure chamber is disposed at a position farther from the main combustion chamber than the auxiliary combustion chamber, and is adjacent to the auxiliary combustion chamber. The second communication passage communicates the auxiliary combustion chamber and the pressure chamber. The pressure adjusting mechanism makes the pressure in the pressure chamber larger than the pressure in the auxiliary combustion chamber in the first period.

  In this sub-chamber internal combustion engine, the pressure adjusting mechanism makes the pressure in the pressure chamber larger than the pressure in the sub-combustion chamber in the first period. Thus, at least one of the residual gas and the fresh air mixture in the pressure chamber can be ejected from the pressure chamber to the auxiliary combustion chamber via the second communication path at the timing when the first period ends.

  In the sub-chamber internal combustion engine according to the present invention, at least one of the residual gas and the fresh air mixture in the pressure chamber can be ejected from the pressure chamber to the sub-combustion chamber at the timing when the first period ends. At least one of the wall surface and the ignition unit can be cooled. For this reason, generation | occurrence | production of a hot surface ignition can be suppressed.

<First Embodiment>
FIG. 1 shows a cross-sectional view of the sub-chamber internal combustion engine according to the first embodiment of the present invention.

(Schematic configuration of sub-chamber internal combustion engine)
The sub-chamber internal combustion engine 1 mainly includes a main combustion chamber 63, an intake / exhaust mechanism, a fuel injection valve 27, a sub-combustion chamber 61, a spark plug 29, and a pressure adjustment mechanism (opening / closing mechanism) 70.

  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. .

  As an intake / exhaust mechanism, an intake valve 21 is disposed downstream of the intake port 23, and an exhaust valve 22 is disposed upstream of the exhaust port 24. The intake cam shaft 25a / exhaust cam shaft 26a fixed to the intake cam shaft 25a / exhaust cam shaft 26a rotating in conjunction with the rotation of the crankshaft are disposed above the intake valve 21 / exhaust valve 22. Then, the intake valve 21 / exhaust valve 22 are opened and closed.

  The fuel injection valve 27 is a valve that injects fuel into the intake port 23. The fuel injection valve 27 is provided so as to penetrate the intake port 23. The tip of the fuel injection valve 27 projects 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. Specifically, the 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, and the auxiliary combustion chamber 61 is formed. In addition, 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 spark plug 29 is provided such that the tip end portion 29 a (ignition part) projects into the auxiliary combustion chamber 61.

  A part of the pressure adjusting mechanism 70 (an on-off valve (valve element) 81) is provided in the sub-combustion chamber 61 so that the pressure in the sub-combustion chamber 61 can be adjusted.

(Schematic operation of sub-chamber internal combustion engine)
In the sub-chamber internal combustion engine 1, pressurized fuel is supplied to the fuel injection valve 27 in the intake stroke. The fuel injection valve 27 injects fuel into fresh air introduced into the intake port 23. Thereby, a fresh air mixture is generated. In the intake stroke, the intake valve 21 is opened by the intake cam 25, and the fresh air mixture is introduced into the main combustion chamber 63 from the intake port 23. The fresh air-fuel mixture introduced from the intake port 23 becomes substantially homogeneous in 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 fresh air mixture 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 through the first communication passage 62, 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 26 is opened by the exhaust cam 26, and the burnt gas burned in the main combustion chamber 63 is discharged to the exhaust port 24 as exhaust gas.

  The pressure adjustment mechanism 70 adjusts the pressure in the auxiliary combustion chamber 61 at a predetermined period or timing.

(Detailed configuration of auxiliary combustion chamber)
FIG. 2 shows an enlarged cross-sectional view of the auxiliary combustion chamber 61. FIG. 3 is a sectional view taken along line III-III in FIG.

  The auxiliary combustion chamber 61 is provided adjacent to the main combustion chamber 63 and is a chamber surrounded by the auxiliary combustion chamber wall 64. The auxiliary combustion chamber 61 has a substantially cylindrical portion and a bulging hemispherical bottom surface. The sub-combustion chamber 61 has a substantially circular cross section perpendicular to the cylinder axis. A plurality of first communication passages 62 communicating with the main combustion chamber 63 and the sub-combustion chamber 61 are formed on the expanded hemispherical bottom surface.

  The spark plug 29 extends in the auxiliary combustion chamber 61 from a position far from the main combustion chamber 63 to a position close to the main combustion chamber 63. The tip end portion 29 a of the spark plug 29 is disposed at a position near the volume center of the auxiliary combustion chamber 61. That is, the spark plug 29 is attached from the upper outside of the sub-combustion chamber 61 so as to penetrate the upper wall (sub-combustion chamber wall 64) downward and the tip portion 29a protrudes into the sub-combustion chamber 61. Yes.

  A pressure chamber 67 is connected to the auxiliary combustion chamber 61 via a second communication passage 68. The pressure chamber 67 is provided at a position farther from the main combustion chamber 63 than the auxiliary combustion chamber 61 and adjacent to the auxiliary combustion chamber 61, and is a chamber surrounded by the pressure chamber wall 66.

  A second communication path 68 is formed on the bottom surface of the pressure chamber 67. The second communication passage 68 communicates the sub-combustion chamber 61 and the pressure chamber 67 and is surrounded by the communication passage wall 65. The second communication passage 68 is provided so as to guide the residual gas and fresh air mixture in the pressure chamber 67 to the inner wall 64 a of the auxiliary combustion chamber 61 and the tip portion 29 a of the spark plug 29.

(Detailed configuration of pressure adjustment mechanism)
The pressure adjustment mechanism 70 mainly includes an on-off valve 81, a drive mechanism (not shown), and a rotating shaft 83. The on-off valve 81 is a rotary valve, is driven by a drive mechanism, and can rotate around the rotary shaft 83 (see the white arrow in FIG. 3). The opening / closing valve 81 has an opening 81a (see FIG. 3). The on-off valve 81 is provided in the second communication path 68 and opens and closes the second communication path 68. That is, when the on-off valve 81 is rotated and the opening 81 a of the on-off valve 81 reaches the position of the second communication path 68, the on-off valve 81 is in an open state and opens the second communication path 68. When the on-off valve 81 is rotated and the opening 81 a of the on-off valve 81 is in a position other than the second communication path 68, the on-off valve 81 is closed and the second communication path 68 is closed. Then, the pressure adjustment mechanism 70 keeps the pressure in the pressure chamber 67 larger than the pressure in the sub-combustion chamber 61 in the first period by closing the second communication path 68 (via the on-off valve 81).

(Detailed operation of auxiliary combustion chamber and pressure adjustment mechanism)
Detailed operations of the auxiliary combustion chamber 61 and the pressure adjusting mechanism 70 are shown in FIG. In FIG. 4, TDC represents the top dead center, and BDC represents the bottom dead center. Po represents the pressure in the standard state.

  As shown in FIG. 4, at the timing (T2) after the timing (T1) when the exhaust valve 22 is closed, the on-off valve 81 is changed from the closed state to the open state. At this time, the pressure in the auxiliary combustion chamber 61 is substantially equal to the pressure Po in the standard state, whereas the pressure in the pressure chamber 67 is larger than the pressure Po in the standard state. For this reason, when the on-off valve 81 is opened and the second communication passage 68 is opened, the residual gas and fresh air mixture in the pressure chamber 67 are ejected from the pressure chamber 67 to the auxiliary combustion chamber 61. The ejected residual gas and fresh air mixture are guided to the inner wall 64a of the sub-combustion chamber 61 and the tip end portion 29a of the spark plug 29, and the pressure rapidly decreases, and the temperature rapidly decreases due to the Joule-Thomson effect. . As a result, the inner wall 64a of the auxiliary combustion chamber 61 and the tip end portion 29a of the spark plug 29 are efficiently cooled. Further, the outer wall 64b of the auxiliary combustion chamber 61 is also cooled by cooling the inner wall 64a of the auxiliary combustion chamber 61. In addition, this timing (T2) is a timing which the above-mentioned 1st period ends.

  In the compression stroke, the second communication passage 68 is opened, and a part of the fresh air mixture in the main combustion chamber 63 passes from the main combustion chamber 63 to the sub-combustion chamber 61 and the second communication passage via the first communication passage 62. It is introduced into the passage 68 and the pressure chamber 67. At this time, the residual gas in the auxiliary combustion chamber 61 is pushed by the fresh air mixture rising upward and pushed into the pressure chamber 67 through the second communication passage 68. As a result, the residual gas in the auxiliary combustion chamber 61 and a part of the fresh air mixture introduced into the auxiliary combustion chamber 61 stay in the pressure chamber 67. Here, the pressure in the pressure chamber 67 is the same as the pressure in the sub-combustion chamber 61. Then, the pressure in the pressure chamber 67 increases from the pressure Po in the standard state as the pressure in the sub-combustion chamber 61 increases.

  In the period (T3 to T5) from when the intake valve 21 is closed until the tip portion 29a of the spark plug 29 is ignited, at the timing (T4) near the top dead center (TDC), the on-off valve 81 is moved from the open state. Closed. That is, the residual gas and the fresh air mixture in the auxiliary combustion chamber 61 are before the timing at which the tip end portion 29a of the spark plug 29 is ignited (hereinafter referred to as ignition timing) (T5) from the timing (T3) when the intake valve 21 is closed. In the period up to the timing (T4), the pressure is taken into the pressure chamber 67 from the auxiliary combustion chamber 61 via the second communication passage 68. This timing (T4) is a timing at which the pressure in the auxiliary combustion chamber 61 becomes maximum before the ignition timing (T5).

  At the subsequent timing (T5), the tip portion 29a of the spark plug 29 ignites the fresh air mixture in the auxiliary combustion chamber 61. The ignited fresh air-fuel mixture rapidly increases in pressure during the combustion period (BT1) of the auxiliary combustion chamber 61 (the pressure becomes maximum at timing T4a) and quickly reaches the first communication passage 62 as a flame. To do. Then, the flame is emitted in a torch shape to the main combustion chamber 63 through the first communication passage 62, and the homogeneous fresh air mixture in the main combustion chamber 63 is combusted during the combustion period (BT2) of the main combustion chamber 63. Let

  Then, the pressure in the auxiliary combustion chamber 61 gradually decreases and becomes smaller than the pressure in the pressure chamber 67 at the timing (T6). That is, this timing (T6) is a timing at which the first period starts. After that, the exhaust valve 22 is opened at timing (T7), and the intake valve 21 is opened at timing (T8).

(Characteristics related to sub-chamber internal combustion engine)
(1)
Here, the pressure adjusting mechanism 70 makes the pressure in the pressure chamber 67 larger than the pressure in the sub-combustion chamber 61 in the first period (T6 to T2 of the next cycle). Thereby, the residual gas and the fresh air mixture in the pressure chamber 67 are ejected from the pressure chamber 67 to the auxiliary combustion chamber 61 via the second communication path 68 at the timing (T2) when the first period ends.

  Thus, since the residual gas and fresh air mixture in the pressure chamber 67 are ejected from the pressure chamber 67 to the auxiliary combustion chamber 61 at the timing (T2) when the first period ends, the wall surfaces 64a and 64b of the auxiliary combustion chamber 61 and ignition are performed. The tip portion 29a of the plug 29 is cooled. For this reason, generation | occurrence | production of a hot surface ignition is suppressed.

(2)
Here, the residual gas and fresh air mixture in the pressure chamber 67 are ejected from the pressure chamber 67 to the auxiliary combustion chamber 61 via the second communication path 68 at the timing (T2) when the first period ends. Then, the pressure of the residual gas and the fresh air mixture ejected drops rapidly, and the temperature rapidly decreases due to the Joule-Thomson effect.

  As described above, the temperature of the residual gas and the fresh air mixture jetted into the auxiliary combustion chamber 61 rapidly decreases, so that the residual gas and the fresh air mixture become the tip of the inner wall 64a of the auxiliary combustion chamber 61 and the spark plug 29. By being led to the portion 29a, the wall surfaces 64a and 64b of the sub-combustion chamber 61 and the tip portion 29a of the spark plug 29 are cooled.

(3)
Here, the timing (T2) when the first period ends is after the timing (T1) when the exhaust valve 22 is closed. That is, the exhaust valve 22 is closed when the residual gas and the fresh air mixture in the pressure chamber 67 are ejected from the pressure chamber 67 to the auxiliary combustion chamber 61.

  Thus, even if fresh air mixture is ejected from the pressure chamber 67 to the main combustion chamber 63 via the sub-combustion chamber 61 and the first communication passage 62, the exhaust valve 22 is closed. Is exhausted without burning.

(4)
Here, the residual gas and the fresh air mixture in the auxiliary combustion chamber 61 are transferred from the auxiliary combustion chamber 61 in the period from the timing (T3) when the intake valve 21 is closed to the timing (T4) before the ignition timing (T5). It is taken into the pressure chamber 67 via the two communication paths 68. As a result, the residual gas in the auxiliary combustion chamber 61 and a part of the fresh air mixture introduced into the auxiliary combustion chamber 61 stay in the pressure chamber 67.

  As described above, the residual gas and the fresh air mixture in the auxiliary combustion chamber 61 are pressured from the auxiliary combustion chamber 61 during the period in which the pressure in the auxiliary combustion chamber 61 is higher than the pressure Po in the standard state (period T3 to T4). Since the pressure is taken into the chamber 67, the pressure in the pressure chamber 67 can be made larger than the pressure in the auxiliary combustion chamber 61 in the first period (T6 to the period T2 of the next cycle).

(5)
Here, the pressure adjustment mechanism 70 has an on-off valve 81. The on-off valve 81 is provided in the second communication passage 68. The on-off valve 81 opens the second communication path 68 when it is open, and closes the second communication path 68 when it is closed.

  As described above, when the pressure adjusting mechanism 70 closes the second communication path 68, the pressure in the pressure chamber 67 becomes larger than the pressure in the sub-combustion chamber 61 in the first period (T6 to T2 of the next cycle). . Further, when the pressure adjusting mechanism 70 opens the second communication passage 68, the residual gas and the fresh air mixture in the pressure chamber 67 are passed from the pressure chamber 67 via the second communication passage 68 at the timing (T2) when the first period ends. Is ejected into the auxiliary combustion chamber 61.

(6)
Here, the on-off valve 81 of the pressure adjusting mechanism 70 closes the second communication path 68 during the combustion period (BT1) of the sub-combustion chamber 61 and the combustion period (BT2) of the main combustion chamber 63. As a result, the intake of high-temperature combustion gas (flame) into the pressure chamber 67 is reduced.

  Thus, since the high-temperature combustion gas is not easily taken into the pressure chamber 67 and the residual gas and the fresh air mixture in the pressure chamber 67 are prevented from becoming high temperature, the residual gas and the fresh air mixture in the pressure chamber 67 are prevented from being heated. When jetted from the pressure chamber 67 to the sub-combustion chamber 61, the wall surfaces 64a and 64b of the sub-combustion chamber 61 and the tip portion 29a of the spark plug 29 are stably cooled.

(7)
Here, the second communication passage 68 is provided to guide the residual gas and the fresh air mixture in the pressure chamber 67 to the inner wall 64 a of the auxiliary combustion chamber 61 and the tip portion 29 a of the spark plug 29. As a result, the residual gas and the fresh air mixture injected from the pressure chamber 67 to the auxiliary combustion chamber 61 via the second communication path 68 are guided to the inner wall 64 a of the auxiliary combustion chamber 61 and the tip portion 29 a of the spark plug 29.

  Thus, since the injected residual gas and fresh air mixture are guided to the inner wall 64a of the auxiliary combustion chamber 61 and the tip portion 29a of the ignition plug 29, the wall surfaces 64a and 64b of the auxiliary combustion chamber 61 and the tip of the ignition plug 29 are provided. The portion 29a is efficiently cooled. As a result, the occurrence of hot surface ignition can be efficiently suppressed.

(Modification of the first embodiment)
(A) The timing (T4) at which the on-off valve 81 of the pressure adjusting mechanism 70 is changed from the open state to the closed state is preferably a timing near the top dead center (TDC), but the timing at which the intake valve 21 is closed (T3). ) To ignition timing (T5), any timing may be used. Even in this case, since the pressure in the auxiliary combustion chamber 61 is higher than the pressure Po in the standard state at the timing (T4) when the on-off valve 81 is changed from the open state to the closed state, the pressure in the pressure chamber 67 is also the standard state pressure Po. Bigger than. For this reason, the pressure in the pressure chamber 67 is set to be higher than the pressure in the sub-combustion chamber 61 in the first period (T6 to the period T2 of the next cycle) in which the pressure in the sub-combustion chamber 61 becomes a value near the pressure Po in the standard state. It can be enlarged.

  The timing (T4) at which the on-off valve 81 is changed from the open state to the closed state is a timing (timing near the top dead center (TDC)) at which the pressure in the auxiliary combustion chamber 61 becomes maximum before the ignition timing (T5). Instead, the timing (T4a) at which the pressure in the auxiliary combustion chamber 61 becomes maximum after the ignition timing (T5) may be used. In this case, the residual gas and the fresh air mixture taken into the pressure chamber 67 from the sub-combustion chamber 61 become high temperature, but the pressure becomes very high. For this reason, the pressure of the residual gas and the fresh air mixture ejected from the pressure chamber 67 to the auxiliary combustion chamber 61 drops very rapidly, and the temperature drops very rapidly due to the Joule-Thomson effect.

  The ignition timing may be a timing (T5a) during a period from the timing (T3) when the intake valve 21 is closed to the top dead center (TDC). In this case, it is preferable that the timing (T4) when the on-off valve 81 is changed from the open state to the closed state is immediately before the ignition timing (T5a). This is because the ignition timing (T5a) is before top dead center (TDC), and the timing at which the pressure in the auxiliary combustion chamber 61 becomes maximum before the ignition timing (T5a) is almost immediately before the ignition timing (T5a). is there.

  (B) The sub-chamber internal combustion engine 1 may further include a third communication passage (not shown) that communicates with the pressure chamber 67 and does not communicate with the sub-combustion chamber 61. The third communication passage is provided so as to guide the fresh air mixture or the like pressurized to a pressure Po or higher in the standard state to the pressure chamber 67. Even in such a configuration, the pressure in the pressure chamber 67 can be made larger than the pressure in the sub-combustion chamber 61 in the first period (period T6 to period T2 of the next cycle).

  In this case, the timing at which the on-off valve 81 is changed from the open state to the closed state (T4) is from the timing at which the on-off valve 81 is changed from the closed state to the open state (T2) to the timing at which the intake valve 21 is closed (T3). It may be the timing during this period. The on-off valve 81 may be changed from the open state to the closed state immediately after being changed from the closed state to the open state.

  (C) Only the fresh air mixture or only the residual gas may stay in the pressure chamber 67 at the timing (T4) when the on-off valve 81 is changed from the open state to the closed state. When only the residual gas stays in the pressure chamber 67, the timing (T2) when the on-off valve 81 is changed from the closed state to the open state is a period from the opening of the exhaust valve 22 to the closing (T7 to the next cycle). During the period up to T1).

  (D) As shown in FIG. 5, the sub-chamber internal combustion engine 1a may further include a cooling mechanism 90a. In this case, the cooling mechanism 90a mainly includes a water jacket 91a. The water jacket 91 a is formed near the pressure chamber 67 in the cylinder head 20. Cooling water is allowed to flow through the water jacket 91a. Thereby, the water jacket 91a of the cooling mechanism 90a cools the residual gas and the fresh air mixture in the pressure chamber 67. For this reason, when the residual gas and the fresh air mixture in the pressure chamber 67 are ejected from the pressure chamber 67 to the auxiliary combustion chamber 61, the wall surfaces 64 a and 64 b (see FIG. 2) of the auxiliary combustion chamber 61 and the tip of the ignition plug 29. The portion 29a is efficiently cooled.

Second Embodiment
FIG. 6 shows a cross-sectional view of the sub-chamber internal combustion engine 100 according to the second embodiment of the present invention. In addition, the same component as 1st Embodiment attaches | subjects the same number, and abbreviate | omits description.

(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, and a pressure adjustment mechanism 170 instead of the pressure adjustment mechanism 70. Other points are the same as in the first embodiment.

(Schematic operation of sub-chamber internal combustion engine)
This is the same as in the first embodiment.

(Detailed configuration of auxiliary combustion chamber)
FIG. 7 shows an enlarged cross-sectional view of the auxiliary combustion chamber 161.

  The auxiliary combustion chamber 161 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 auxiliary combustion chamber 161 has a substantially cylindrical shape. The sub-combustion chamber 161 has a substantially circular cross section perpendicular to the cylinder axis. A plurality of first communication passages 62 communicating the main combustion chamber 63 and the sub-combustion chamber 161 are formed on the expanded hemispherical bottom surface.

  The spark plug 129 extends in the auxiliary combustion chamber 161 from a position far from the main combustion chamber 63 to a position close to the main combustion chamber 63. A tip portion (ignition part) 129 a of the spark plug 129 is disposed at a position near the volume center of the auxiliary combustion chamber 161. That is, the spark plug 129 is attached from the outside of the sub-combustion chamber 161 so as to penetrate the side wall (sub-combustion chamber wall 164) obliquely downward and the tip portion 129a protrudes into the sub-combustion chamber 161.

  A pressure chamber 167 is connected to the sub-combustion chamber 161 via a second communication passage 168. The pressure chamber 167 is provided at a position farther from the main combustion chamber 63 than the auxiliary combustion chamber 161 and adjacent to the auxiliary combustion chamber 161, and is a chamber surrounded by the pressure chamber wall 166 and the baffle plate 165. is there. The pressure chamber 167 has a substantially cylindrical shape.

  The baffle plate 165 is opened in the vicinity of the center of gravity to form a second communication path 168. The second communication passage 168 communicates the auxiliary combustion chamber 161 and the pressure chamber 167 and is surrounded by a baffle plate 165. The second communication passage 168 is provided to guide the residual gas and fresh air mixture in the pressure chamber 167 to the inner wall 164a of the auxiliary combustion chamber 161 and the tip portion 129a of the spark plug 129.

(Detailed configuration of pressure adjustment mechanism)
The pressure adjustment mechanism (open / close mechanism) 170 mainly includes an open / close valve (valve element) 181 and an actuator 182. The actuator 182 mainly includes a cam shaft 171, a cam 175, a tappet 173, a spring 174, and a housing 178.

  A cam 175 fixed to the cam shaft 171 that rotates in conjunction with the rotation of the crankshaft is disposed above the on-off valve 181 and moves the on-off valve 181 up and down via the tappet 173 (the white arrow in FIG. 7). reference). The on-off valve 181 is a needle valve, has a substantially conical shape with a sharp tip, penetrates the upper wall (pressure chamber wall 166) downward from the outside above the pressure chamber 167, and the tip portion is the pressure chamber 167. Alternatively, it is provided so as to protrude into the second communication passage 168. For this reason, the on-off valve 181 opens and closes the second communication path 168 by moving up and down. That is, when the on-off valve 181 moves upward and the tip of the on-off valve 181 is at a position away from the baffle plate 165, the on-off valve 181 is opened and the second communication passage 168 is opened. When the on-off valve 181 moves downward and the tip of the on-off valve 181 comes into contact with the baffle plate 165, the on-off valve 181 is closed and the second communication path 168 is closed. Then, the pressure adjusting mechanism 170 keeps the pressure in the pressure chamber 167 higher than the pressure in the sub-combustion chamber 161 in the first period by closing the second communication passage 168 (via the on-off valve 181).

  The actuator 182 moves the open / close valve 181 up and down via the cam 175, so that the structure is easy and the reliability is high.

(Detailed operation of auxiliary combustion chamber and pressure adjustment mechanism)
Detailed operations of the auxiliary combustion chamber 161 and the pressure adjustment mechanism 170 are shown in FIG. In FIG. 4, TDC represents the top dead center, and BDC represents the bottom dead center. Po represents the pressure in the standard state.

  As shown in FIG. 4, at the timing (T2) after the timing (T1) when the exhaust valve 22 is closed, the on-off valve 181 is changed from the closed state to the open state. At this time, the on-off valve 181 has a substantially conical shape with a sharp tip, and thus quickly opens the second communication passage 168 when the open state is changed from the closed state. The pressure in the auxiliary combustion chamber 161 is substantially equal to the pressure Po in the standard state, whereas the pressure in the pressure chamber 167 is larger than the pressure Po in the standard state. For this reason, when the on-off valve 181 is opened and the second communication passage 168 is opened, the residual gas and the fresh air mixture in the pressure chamber 167 are quickly ejected from the pressure chamber 167 to the auxiliary combustion chamber 161. The residual gas and the fresh air mixture rapidly ejected are guided to the inner wall 164a of the auxiliary combustion chamber 161 and the tip portion 129a of the spark plug 129, and the pressure rapidly decreases and the temperature rapidly increases due to the Joule-Thomson effect. descend. Thereby, the wall surfaces 164a and 164b of the auxiliary combustion chamber 161 and the tip portion 129a of the spark plug 129 are efficiently cooled. In addition, this timing (T2) is a timing which the above-mentioned 1st period ends.

  During the period (T3 to T5) from when the intake valve 21 is closed to when the tip portion 129a of the spark plug 129 is ignited (T4) near the top dead center (TDC), the on-off valve 181 is moved from the open state. Closed. At this time, the on-off valve 181 is a needle valve, and has a substantially conical shape with a sharp tip, and therefore quickly closes the second communication path 168 when the open state is closed. That is, immediately after the pressure in the auxiliary combustion chamber 161 reaches the maximum before the ignition timing (T5), the on-off valve 181 is changed from the open state to the closed state, so that the pressure in the pressure chamber 167 is changed to the ignition timing ( It becomes a value substantially equal to the maximum value of the pressure in the auxiliary combustion chamber 161 before T5).

  Other points are the same as in the first embodiment.

(Characteristics related to sub-chamber internal combustion engine)
(1)
Here, the pressure adjustment mechanism 170 makes the pressure in the pressure chamber 167 larger than the pressure in the auxiliary combustion chamber 161 in the first period (T6 to T2 of the next cycle). Thereby, the residual gas and fresh air mixture in the pressure chamber 167 are jetted from the pressure chamber 167 to the auxiliary combustion chamber 161 via the second communication path 168 at the timing (T2) when the first period ends.

  Thus, since the residual gas and fresh air mixture in the pressure chamber 167 are ejected from the pressure chamber 167 to the auxiliary combustion chamber 161 at the timing (T2) when the first period ends, the wall surfaces 164a and 164b of the auxiliary combustion chamber 161 and ignition are performed. The tip portion 129a of the plug 129 is cooled. For this reason, generation | occurrence | production of a hot surface ignition is suppressed.

(2)
Here, the residual gas and fresh air mixture in the pressure chamber 167 are ejected from the pressure chamber 167 to the auxiliary combustion chamber 161 via the second communication passage 168 at the timing (T2) when the first period ends. Then, the pressure of the residual gas and the fresh air mixture ejected drops rapidly, and the temperature rapidly decreases due to the Joule-Thomson effect.

  As described above, the temperature of the residual gas and the fresh air mixture jetted into the auxiliary combustion chamber 161 is drastically lowered, so that the residual gas and the fresh air mixture become the inner wall 164a of the auxiliary combustion chamber 161 and the tip of the spark plug 129. By being guided to the portion 129a, the wall surfaces 164a and 164b of the auxiliary combustion chamber 161 and the tip portion 129a of the spark plug 129 are cooled.

(3)
Here, the timing (T2) when the first period ends is after the timing (T1) when the exhaust valve 22 is closed. That is, when the residual gas and the fresh air mixture in the pressure chamber 167 are ejected from the pressure chamber 167 to the sub-combustion chamber 161, the exhaust valve 22 is closed.

  As described above, the exhaust valve 22 is closed even when the fresh air mixture is ejected from the pressure chamber 167 via the sub-combustion chamber 161 and the first communication passage 62, so the fresh air mixture is closed. Is exhausted without burning.

(4)
Here, the residual gas and fresh air mixture in the auxiliary combustion chamber 161 from the timing (T3) when the intake valve 21 is closed to the timing (T4) before the timing (T5) when the tip portion 129a of the spark plug 129 is ignited. In the period, the secondary combustion chamber 161 takes in the pressure chamber 167 via the second communication path 168. As a result, the residual gas in the auxiliary combustion chamber 161 and a part of the fresh air mixture introduced into the auxiliary combustion chamber 161 stay in the pressure chamber 167.

  As described above, the residual gas and the fresh air mixture in the auxiliary combustion chamber 161 are pressured from the auxiliary combustion chamber 161 during the period in which the pressure in the auxiliary combustion chamber 161 is higher than the pressure Po in the standard state (period T3 to T4). Since the pressure is taken into the chamber 167, the pressure in the pressure chamber 167 can be made larger than the pressure in the auxiliary combustion chamber 161 in the first period (T6 to the period T2 of the next cycle).

(5)
Here, the pressure adjustment mechanism 170 has an on-off valve 181. The on-off valve 181 is provided in the second communication passage 168. The on-off valve 181 opens the second communication path 168 when it is open, and closes the second communication path 168 when it is closed.

  As described above, when the pressure adjusting mechanism 170 closes the second communication path 168, the pressure in the pressure chamber 167 becomes larger than the pressure in the sub-combustion chamber 161 in the first period (T6 to T2 of the next cycle). . Further, when the pressure adjusting mechanism 170 opens the second communication passage 168, the residual gas and the fresh air mixture in the pressure chamber 167 pass from the pressure chamber 167 via the second communication passage 168 at the timing (T2) when the first period ends. Is ejected into the auxiliary combustion chamber 161.

(6)
Here, the on-off valve 181 of the pressure adjustment mechanism 170 closes the second communication passage 168 during the combustion period (BT1) of the auxiliary combustion chamber 161 and the combustion period (BT2) of the main combustion chamber 63. As a result, the intake of high-temperature combustion gas (flame) into the pressure chamber 167 is reduced.

  Thus, since the high-temperature combustion gas is not easily taken into the pressure chamber 167 and the residual gas and the fresh air mixture in the pressure chamber 167 are prevented from becoming high temperature, the residual gas and the fresh air mixture in the pressure chamber 167 When jetted from the pressure chamber 167 to the auxiliary combustion chamber 161, the wall surfaces 164a and 164b of the auxiliary combustion chamber 161 and the tip portion 129a of the spark plug 129 are stably cooled.

(7)
Here, the second communication passage 168 is provided to guide the residual gas and fresh air mixture in the pressure chamber 167 to the inner wall 164a of the auxiliary combustion chamber 161 and the tip portion 129a of the spark plug 129. As a result, the residual gas and the fresh air mixture injected from the pressure chamber 167 to the auxiliary combustion chamber 161 via the second communication passage 168 are guided to the inner wall 164a of the auxiliary combustion chamber 161 and the tip portion 129a of the spark plug 129.

  Thus, since the injected residual gas and fresh air mixture are guided to the inner wall 164a of the auxiliary combustion chamber 161 and the tip portion 129a of the ignition plug 129, the wall surfaces 164a and 164b of the auxiliary combustion chamber 161 and the tip of the ignition plug 129 are provided. The portion 129a is efficiently cooled. As a result, the occurrence of hot surface ignition can be efficiently suppressed.

(8)
Here, the on-off valve 181 has a substantially conical shape with a sharp tip, and thus quickly opens the second communication path 168 when the open state is changed from the closed state. As a result, the residual gas and the fresh air mixture in the pressure chamber 167 are rapidly ejected from the pressure chamber 167 to the auxiliary combustion chamber 161 via the second communication passage 168 at the timing (T2) when the first period ends.

  Further, since the on-off valve 181 has a substantially conical shape with a sharp tip, the on-off valve 181 quickly closes the second communication path 168 when the open state is changed to the closed state. For this reason, immediately after the pressure of the auxiliary combustion chamber 161 reaches the maximum before the ignition timing (T5), the on-off valve 181 is changed from the open state to the closed state, so that the pressure in the pressure chamber 167 is changed to the ignition timing. It becomes a value substantially equal to the maximum value of the pressure in the auxiliary combustion chamber 161 before (T5).

  Thus, the pressure in the pressure chamber 167 becomes substantially equal to the maximum value of the pressure in the auxiliary combustion chamber 161 before the ignition timing (T5), and the residual gas and the fresh air mixture in the pressure chamber 167 become the pressure chamber 167. Is quickly ejected into the auxiliary combustion chamber 161, so that the wall surfaces 164a and 164b of the auxiliary combustion chamber 161 and the tip portion 129a of the spark plug 129 are reliably cooled.

(9)
Here, the on-off valve 181 of the pressure adjustment mechanism 170 has a substantially conical shape with a sharp tip, and is driven by the actuator 182. The actuator 182 moves the open / close valve 181 up and down via the cam 175.

  Thus, since the on-off valve 181 is driven easily and the pressure adjustment mechanism 170 has a simple configuration, the pressure adjustment mechanism 170 is downsized.

(Modification of the second embodiment)
(A) As shown in FIG. 8, the pressure adjustment mechanism 170 a may include an actuator 182 a instead of the actuator 182. At this time, the actuator 182a mainly includes a high pressure valve 171a, a low pressure valve 172a, a tappet 173, a spring 174, a hydraulic chamber 175a, a first passage 176a, a second passage 177a, and a housing 178a.

  The high-pressure valve 171a is connected to the hydraulic chamber 175a via the first passage 176a. The low pressure valve 172a is connected to the hydraulic chamber 175a via the second passage 177a. The hydraulic chamber 175a is a chamber surrounded by the housing 178a and the tappet 173. The tappet 173 can move along the inner wall of the housing 178a. The tappet 173 is provided so as to be stable at a position where the force received from the spring 174 and the force generated by the hydraulic pressure in the hydraulic chamber 175a are balanced.

  The on-off valve 181 and the tappet 173 are connected, and a force corresponding to the difference between the force received from the spring 174 and the hydraulic pressure of the hydraulic chamber 175a is transmitted to the on-off valve 181 via the tappet 173. Yes.

  When the high pressure valve 171a is opened and the low pressure valve 172a is closed, high pressure oil pressure is transmitted to the hydraulic chamber 175a via the high pressure valve 171a and the first passage 176a. As a result, the hydraulic pressure in the hydraulic chamber 175a increases. The tappet 173 is lowered downward in the drawing due to the increase in the hydraulic pressure in the hydraulic chamber 175a. The operation of the tappet 173 is transmitted to the on-off valve 181 and pushes down the on-off valve 181. Thereby, the on-off valve 181 is closed.

  On the other hand, when the high pressure valve 171a is closed and the low pressure valve 172a is opened, the low pressure hydraulic pressure is transmitted to the hydraulic chamber 175a via the low pressure valve 172a and the second passage 177a. Thereby, the hydraulic pressure in the hydraulic chamber 175a is lowered. Then, the tappet 173 rises upward in the drawing because the hydraulic pressure in the hydraulic chamber 175a is lowered. The operation of the tappet 173 is transmitted to the on-off valve 181 and raises the on-off valve 181. As a result, the on-off valve 181 is opened.

  Even in this case, the pressure in the pressure chamber 167 becomes substantially equal to the maximum value of the pressure in the auxiliary combustion chamber 161 before the ignition timing (T5), and the residual gas and the fresh air mixture in the pressure chamber 167 become the pressure chamber 167. Is quickly ejected into the auxiliary combustion chamber 161, so that the wall surfaces 164a and 164b of the auxiliary combustion chamber 161 and the tip portion 129a of the spark plug 129 are reliably cooled.

  Since the actuator 182a moves the on-off valve 181 up and down via hydraulic pressure, it has a high degree of variable freedom, can be controlled according to the rotational speed of the sub-chamber internal combustion engine 100, and is relatively reliable.

  (B) As shown in FIG. 9, the pressure adjustment mechanism 170 b may include an actuator 182 b instead of the actuator 182. At this time, the actuator 182b mainly includes an electromagnetic coil 175b, a spring 174, a moving member 173b, and a housing 178b. The moving member 173b can move up and down in the direction along the inner wall of the housing 178b. And the moving member 173b is provided so that it may be stabilized in the position where the force received from the spring 174 and the electromagnetic force received from the electromagnetic coil 175b balance.

  When a current flows through the electromagnetic coil 175b and a magnetic field is generated, a downward electromagnetic force acts on the moving member 173b. The moving member 173b is lowered downward in the drawing by receiving the downward electromagnetic force. The operation of the moving member 173b is transmitted to the connected on-off valve 181 and pushes down the on-off valve 181. Thereby, the on-off valve 181 is closed.

  On the other hand, when no magnetic field is generated without a current flowing through the electromagnetic coil 175b, the electromagnetic force does not act on the moving member 173b. The moving member 173b moves upward in the drawing when the electromagnetic force stops working. The operation of the moving member 173b is transmitted to the on-off valve 181 to raise the on-off valve 181. As a result, the on-off valve 181 is opened.

  Even in this case, the pressure in the pressure chamber 167 becomes substantially equal to the maximum value of the pressure in the auxiliary combustion chamber 161 before the ignition timing (T5), and the residual gas and the fresh air mixture in the pressure chamber 167 become the pressure chamber 167. Is quickly ejected into the auxiliary combustion chamber 161, so that the wall surfaces 164a and 164b of the auxiliary combustion chamber 161 and the tip portion 129a of the spark plug 129 are reliably cooled.

  Note that the moving member 173b is separated from the electromagnetic coil 175b when a current flows through the electromagnetic coil 175b and a magnetic field is generated, and the moving member 173b is electromagnetic when no current flows through the electromagnetic coil 175b. It may be attracted to the coil 175b. Further, the actuator 182b moves the open / close valve 181 up and down via electromagnetic force, so that the response speed is high.

  (C) As shown in FIG. 10, the pressure adjustment mechanism 170 c may include an actuator 182 c instead of the actuator 182. At this time, the actuator 182c mainly includes a piezoelectric body 173c, a spring 174, and a housing 178c. The piezoelectric body 173c can be expanded and contracted in a direction along the inner wall of the housing 178c. The piezoelectric body 173c is provided so as to be stable at a position where the force received from the spring 174 and the force due to the reverse piezo effect are balanced.

  When a voltage is applied to the piezoelectric body 173c, the piezoelectric body 173c is deformed so as to extend up and down due to an inverse piezoelectric effect. The on-off valve 181 is connected to the piezoelectric body 173c, and is lowered downward in the drawing when the piezoelectric body 173c extends vertically. Thereby, the on-off valve 181 is closed.

  On the other hand, when the voltage is no longer applied to the piezoelectric body 173c, the piezoelectric body 173c contracts up and down to the original size. The on-off valve 181 moves upward in the drawing as the piezoelectric body 173c contracts up and down to the original size. As a result, the on-off valve 181 is opened.

  Even in this case, the pressure in the pressure chamber 167 becomes substantially equal to the maximum value of the pressure in the auxiliary combustion chamber 161 before the ignition timing (T5), and the residual gas and the fresh air mixture in the pressure chamber 167 become the pressure chamber 167. Is quickly ejected into the auxiliary combustion chamber 161, so that the wall surfaces 164a and 164b of the auxiliary combustion chamber 161 and the tip portion 129a of the spark plug 129 are reliably cooled.

  In addition, when a voltage is applied to the piezoelectric body 173c, the piezoelectric body 173c is deformed so as to contract vertically due to the reverse piezo effect, and when no voltage is applied to the piezoelectric body 173c, the piezoelectric body 173c expands vertically and is restored to the original. It may be a size. Further, the actuator 182c moves the open / close valve 181 up and down via a force due to the reverse piezo effect, so the response speed is fast.

<Third Embodiment>
FIG. 11 shows a cross-sectional view of a sub-chamber internal combustion engine 200 according to the third embodiment of the present invention. In addition, the same component as 1st Embodiment attaches | subjects the same number, and abbreviate | omits description.

(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, and a pressure adjustment mechanism 270 instead of the pressure adjustment mechanism 70. Other points are the same as in the first embodiment.

(Schematic operation of sub-chamber internal combustion engine)
This is the same as in the first embodiment.

(Detailed configuration of auxiliary combustion chamber)
FIG. 12 shows an enlarged cross-sectional view of the auxiliary combustion chamber 261.

  The auxiliary combustion chamber 261 is provided adjacent to the main combustion chamber 63, and is a chamber surrounded by the auxiliary combustion chamber wall 264 and the baffle plate 265. The auxiliary combustion chamber 261 has a substantially cylindrical shape. The sub-combustion chamber 261 has a substantially circular cross section perpendicular to the cylinder axis. A plurality of first communication passages 62 communicating with the main combustion chamber 63 and the auxiliary combustion chamber 261 are formed on the bulged hemispherical bottom surface.

  A pressure chamber 267 is connected to the auxiliary combustion chamber 261 via a second communication path 268. The pressure chamber 267 is provided at a position farther from the main combustion chamber 63 than the auxiliary combustion chamber 261 and adjacent to the auxiliary combustion chamber 261, and is a chamber surrounded by the pressure chamber wall 266 and the baffle plate 265. is there. The pressure chamber 267 has a substantially cylindrical shape.

  A first electrode 281a (ignition part), which is a tip portion of an on-off valve (valve element) 281 described later, is in a main combustion from a position far from the main combustion chamber 63 in the pressure chamber 267, the second communication passage 268, and the auxiliary combustion chamber 261. It extends to a position close to the chamber 63. The second electrode 264c (ignition part) of the on-off valve 281 moves from the portion close to the main combustion chamber 63 of the auxiliary combustion chamber wall 264 to a position far from the main combustion chamber 63 in the auxiliary combustion chamber 261 (direction toward the first electrode 281a). E). The second electrode 264c and the auxiliary combustion chamber wall 264 are electrically connected, and the first electrode 281a and the second electrode 264c are electrically insulated. When the on-off valve 281 is closed, the distance between the first electrode 281a and the second electrode 264c becomes closer, and the fresh air mixture in the auxiliary combustion chamber 261 can be ignited. On the other hand, when the on-off valve 281 is opened, the distance between the first electrode 281a and the second electrode 264c is increased, and it becomes difficult to ignite the fresh air mixture in the auxiliary combustion chamber 261. The first electrode 281a of the on-off valve 281 and the baffle plate 265 are electrically insulated even when in contact with each other. In addition, no ignition plug is provided.

  The baffle plate 265 has a second communication passage 268 formed in the vicinity of the center of gravity thereof. The second communication passage 268 communicates with the auxiliary combustion chamber 261 and the pressure chamber 267 and is surrounded by a baffle plate 265. The second communication passage 268 is provided to guide the residual gas and fresh air mixture in the pressure chamber 267 to the inner wall 264a of the auxiliary combustion chamber 261 and the first electrode 281a and the second electrode 264c.

(Detailed configuration of pressure adjustment mechanism)
The pressure adjusting mechanism (opening / closing mechanism) 270 includes an opening / closing valve 281 instead of the opening / closing valve 181. The opening / closing valve 281 has a first electrode 281a formed at the tip thereof. As described above, when the on-off valve 281 is closed, the fresh air mixture in the auxiliary combustion chamber 261 can be ignited, and when the on-off valve 281 is opened, the auxiliary combustion chamber 261 is ignited. It becomes difficult to ignite the fresh air mixture. Other points are the same as those in the first and second embodiments.

(Detailed operation of auxiliary combustion chamber and pressure adjustment mechanism)
Detailed operations of the auxiliary combustion chamber 261 and the pressure adjustment mechanism 270 are shown in FIG. In FIG. 4, TDC represents the top dead center, and BDC represents the bottom dead center. Po represents the pressure in the standard state.

  As shown in FIG. 4, the timing (T4) near the top dead center (TDC) during the period (T3 to T5) from when the intake valve 21 is closed until the first electrode 281a and the second electrode 264c are ignited. ), The on-off valve 281 is changed from the open state to the closed state. At this time, since the fresh air mixture in the auxiliary combustion chamber 261 can be ignited when the on-off valve 281 is in the closed state, the auxiliary air-fuel mixture can be ignited immediately after the on-off valve 281 is changed from the open state to the closed state. The fresh air mixture in the combustion chamber 261 can be ignited. That is, it is easy to bring the timing (T4) close to the timing (T5).

  Other points are the same as in the first and second embodiments.

(Characteristics related to sub-chamber internal combustion engine)
(1)
Here, the pressure adjustment mechanism 270 makes the pressure in the pressure chamber 267 larger than the pressure in the auxiliary combustion chamber 261 in the first period (T6 to T2 of the next cycle). Thereby, the residual gas and the fresh air mixture in the pressure chamber 267 are ejected from the pressure chamber 267 to the auxiliary combustion chamber 261 via the second communication path 268 at the timing (T2) when the first period ends.

  Thus, since the residual gas and fresh air mixture in the pressure chamber 267 are ejected from the pressure chamber 267 to the auxiliary combustion chamber 261 at the timing (T2) when the first period ends, the wall surfaces 264a and 264b of the auxiliary combustion chamber 261 and the second The first electrode 281a and the second electrode 264c are cooled. For this reason, generation | occurrence | production of a hot surface ignition is suppressed.

(2)
Here, the residual gas and fresh air mixture in the pressure chamber 267 are ejected from the pressure chamber 267 to the auxiliary combustion chamber 261 via the second communication path 268 at the timing (T2) when the first period ends. Then, the pressure of the residual gas and the fresh air mixture ejected drops rapidly, and the temperature rapidly decreases due to the Joule-Thomson effect.

  In this way, the temperature of the residual gas and fresh air mixture jetted into the auxiliary combustion chamber 261 rapidly decreases, so that the residual gas and fresh air mixture become the inner wall 264a of the auxiliary combustion chamber 261 and the first electrode 281a. By being guided to the second electrode 264c, the wall surfaces 264a and 264b of the auxiliary combustion chamber 261 and the first electrode 281a and the second electrode 264c are cooled.

(3)
Here, the timing (T2) when the first period ends is after the timing (T1) when the exhaust valve 22 is closed. That is, when the residual gas and the fresh air mixture in the pressure chamber 267 are ejected from the pressure chamber 267 to the auxiliary combustion chamber 261, the exhaust valve 22 is closed.

  As described above, since the exhaust valve 22 is closed even when the fresh air mixture is ejected from the pressure chamber 267 via the sub-combustion chamber 261 and the first communication passage 62, the fresh air mixture is closed. Is exhausted without burning.

(4)
Here, the residual gas and the fresh air mixture in the auxiliary combustion chamber 261 are timing (T4) before the timing (T5) when the first electrode 281a and the second electrode 264c are ignited from the timing (T3) when the intake valve 21 is closed. In the period up to, the auxiliary combustion chamber 261 is taken into the pressure chamber 267 via the second communication path 268. As a result, the residual gas in the auxiliary combustion chamber 261 and a part of the fresh air mixture introduced into the auxiliary combustion chamber 261 stay in the pressure chamber 267.

  As described above, the residual gas and the fresh air mixture in the auxiliary combustion chamber 261 are pressured from the auxiliary combustion chamber 261 during the period in which the pressure in the auxiliary combustion chamber 261 is higher than the pressure Po in the standard state (period T3 to T4). Since the pressure is taken into the chamber 267, the pressure in the pressure chamber 267 can be made larger than the pressure in the auxiliary combustion chamber 261 in the first period (T6 to T2 of the next cycle).

(5)
Here, the pressure adjustment mechanism 270 has an on-off valve 281. The on-off valve 281 is provided in the second communication path 268. The on-off valve 281 opens the second communication path 268 when it is opened, and closes the second communication path 268 when it is closed.

  As described above, when the pressure adjusting mechanism 270 closes the second communication path 268, the pressure in the pressure chamber 267 becomes larger than the pressure in the sub-combustion chamber 261 in the first period (T6 to T2 of the next cycle). . Further, when the pressure adjusting mechanism 270 opens the second communication passage 268, the residual gas and the fresh air mixture in the pressure chamber 267 pass through the second communication passage 268 from the pressure chamber 267 at the timing (T 2) when the first period ends. Is ejected into the auxiliary combustion chamber 261.

(6)
Here, the on-off valve 281 of the pressure adjustment mechanism 270 closes the second communication passage 268 during the combustion period (BT1) of the auxiliary combustion chamber 261 and the combustion period (BT2) of the main combustion chamber 63. As a result, the intake of high-temperature combustion gas (flame) into the pressure chamber 267 is reduced.

  As described above, since the high-temperature combustion gas is not easily taken into the pressure chamber 267 and the residual gas and the fresh air mixture in the pressure chamber 267 are prevented from becoming high temperature, the residual gas and the fresh air mixture in the pressure chamber 267 are prevented from being heated. When jetted from the pressure chamber 267 to the sub-combustion chamber 261, the wall surfaces 264a, 264b and the first electrode 281a / second electrode 264c of the sub-combustion chamber 261 are stably cooled.

(7)
Here, the second communication passage 268 is provided to guide the residual gas and fresh air mixture in the pressure chamber 267 to the inner wall 264a of the auxiliary combustion chamber 261 and the first electrode 281a and the second electrode 264c. As a result, the residual gas and the fresh air mixture injected from the pressure chamber 267 to the auxiliary combustion chamber 261 via the second communication passage 268 are guided to the inner wall 264a of the auxiliary combustion chamber 261 and the first electrode 281a / second electrode 264c. It is burned.

  Thus, since the injected residual gas and fresh air mixture are guided to the inner wall 264a of the auxiliary combustion chamber 261 and the first electrode 281a / second electrode 264c, the wall surfaces 264a, 264b of the auxiliary combustion chamber 261 and the first electrode 281a and the second electrode 264c are efficiently cooled. As a result, the occurrence of hot surface ignition can be efficiently suppressed.

(8)
Here, the on-off valve 281 has a substantially conical shape with a sharp tip, and thus quickly opens the second communication passage 268 when the valve is switched from the closed state to the open state. Thereby, the residual gas and the fresh air mixture in the pressure chamber 267 are rapidly ejected from the pressure chamber 267 to the auxiliary combustion chamber 261 via the second communication path 268 at the timing (T2) when the first period ends.

  Moreover, since the on-off valve 281 has a substantially conical shape with a sharp tip, the on-off valve 281 quickly closes the second communication path 268 when the open state is changed to the closed state. For this reason, immediately after the pressure in the auxiliary combustion chamber 261 reaches the maximum before the ignition timing (T5), the on-off valve 281 is changed from the open state to the closed state, so that the pressure in the pressure chamber 267 is changed to the ignition timing. It becomes substantially equal to the maximum value of the pressure in the auxiliary combustion chamber 261 before (T5).

  Thus, the pressure in the pressure chamber 267 becomes substantially equal to the maximum value of the pressure in the auxiliary combustion chamber 261 before the ignition timing (T5), and the residual gas and the fresh air mixture in the pressure chamber 267 become the pressure chamber 267. Is quickly ejected into the auxiliary combustion chamber 261, so that the wall surfaces 264a and 264b and the first electrode 281a and the second electrode 264c of the auxiliary combustion chamber 261 are reliably cooled.

(9)
Here, the on-off valve 281 of the pressure adjusting mechanism 270 has a substantially conical shape with a sharp tip, and is driven by an actuator 182 (see FIG. 7). The actuator 182 moves the open / close valve 281 up and down via a cam 175 (see FIG. 7).

  Thus, since the on-off valve 281 is driven easily and the pressure adjustment mechanism 270 has a simple configuration, the pressure adjustment mechanism 270 is downsized.

(10)
Here, the first electrode 281 a is provided at the tip of the on-off valve 281, the second electrode 264 c is provided so as to extend from the wall surface 264 a of the auxiliary combustion chamber 261, and the first electrode 281 a and the second electrode 264 c are electrically connected. Since it is insulated, it is not necessary to provide a spark plug separately from the on-off valve 281. For this reason, the auxiliary combustion chamber 261 is reduced in size. In addition, since it becomes easy to ignite the fresh air mixture in the auxiliary combustion chamber 261 at a position close to the main combustion chamber 63, the flame is efficiently injected from the auxiliary combustion chamber 261 to the main combustion chamber 63, and operation is possible. The air-fuel ratio region expands. Furthermore, the residual gas and the fresh air mixture in the pressure chamber 267 can be easily guided to the wall surfaces 264a and 264b of the auxiliary combustion chamber 261 and the first electrode 281a and the second electrode 264c. H.264b and the first electrode 281a and the second electrode 264c are efficiently cooled.

(11)
Here, when the on-off valve 281 is closed, the distance between the first electrode 281a and the second electrode 264c becomes closer, and the fresh air mixture in the auxiliary combustion chamber 261 can be ignited. On the other hand, when the on-off valve 281 is opened, the distance between the first electrode 281a and the second electrode 264c is increased, and it becomes difficult to ignite the fresh air mixture in the auxiliary combustion chamber 261.

  As described above, since the fresh air mixture in the auxiliary combustion chamber 261 can be ignited when the on-off valve 281 is closed, immediately after the on-off valve 281 is changed from the open state to the closed state. The fresh air mixture in the auxiliary combustion chamber 261 can be ignited. That is, it is easy to bring the timing (T4) close to the timing (T5).

(Modification of the third embodiment)
In the sub-chamber internal combustion engine 200, when the first electrode 281a of the on-off valve 281 and the baffle plate 265 are in contact with each other, the baffle plate 265 and the sub-combustion chamber wall 264 are electrically insulated instead of being electrically insulated. May be electrically insulated. Even in this case, the first electrode 281a and the second electrode 264c are electrically insulated.

  The sub-chamber internal combustion engine according to the present invention has an effect of suppressing the occurrence of hot surface ignition, and is useful as a sub-chamber internal combustion engine or the like.

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. III-III sectional drawing of FIG. The figure which shows detailed operation | movement of a subcombustion chamber and a pressure adjustment mechanism. Sectional drawing of the subchamber internal combustion engine which concerns on the modification of 1st Embodiment of this invention. Sectional drawing of the subchamber internal combustion engine which concerns on 2nd Embodiment of this invention. The expanded sectional view of the subcombustion chamber in a 2nd embodiment of the present invention. The expanded sectional view of the auxiliary combustion chamber in the modification of a 2nd embodiment of the present invention. The expanded sectional view of the auxiliary combustion chamber in the modification of 2nd Embodiment of this invention. The expanded sectional view of the auxiliary combustion chamber in the modification of a 2nd embodiment of the present invention. Sectional drawing of the subchamber internal combustion engine which concerns on 3rd Embodiment of this invention. The expanded sectional view of the subcombustion chamber in a 3rd embodiment of the present invention.

Explanation of symbols

1,100,200 Sub-chamber internal combustion engine 29,129 Spark plugs 29a, 129a Tip portion (ignition part)
61, 161, 261 Sub-combustion chamber 62 First communication passage 63 Main combustion chamber 67, 167, 267 Pressure chamber 68, 168, 268 Second communication passage 70, 170, 270 Pressure adjustment mechanism (opening / closing mechanism)
81,181,281 On-off valve (valve element)
90a Cooling mechanism 182, 182a, 182b, 182c Actuator 264c Second electrode (ignition part)
281a First electrode (ignition part)

Claims (13)

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;
An igniter provided in the auxiliary combustion chamber for igniting a fresh air mixture introduced from the main combustion chamber into the auxiliary combustion chamber via the first communication passage;
A pressure chamber located farther from the main combustion chamber than the sub-combustion chamber, and adjacent to the sub-combustion chamber;
A second communication path communicating the sub-combustion chamber and the pressure chamber;
A pressure adjusting mechanism for making the pressure in the pressure chamber larger than the pressure in the sub-combustion chamber in the first period;
With
Sub-chamber internal combustion engine. At least one of the residual gas and the fresh air mixture in the pressure chamber is ejected from the pressure chamber to the auxiliary combustion chamber at a timing when the first period ends.
The sub-chamber internal combustion engine according to claim 1. The timing when the first period ends is after the exhaust valve is closed.
The sub-chamber internal combustion engine according to claim 1 or 2. At least one of the residual gas and the fresh air mixture in the auxiliary combustion chamber is taken into the pressure chamber from the auxiliary combustion chamber in a period from the timing when the intake valve closes to the timing before the ignition unit ignites.
The sub-chamber internal combustion engine according to any one of claims 1 to 3. The pressure adjusting mechanism has an opening / closing mechanism for opening / closing the second communication path,
The sub-chamber internal combustion engine according to any one of claims 1 to 4. The opening / closing mechanism closes the second communication path in at least one of a combustion period of the sub-combustion chamber and a combustion period of the main combustion chamber;
The sub-chamber internal combustion engine according to claim 5. The opening / closing mechanism includes a valve body provided so as to open and close the second communication path.
The sub-chamber internal combustion engine according to claim 5 or 6. The valve body has a substantially conical shape with a sharp tip,
The sub-chamber internal combustion engine according to claim 7. The opening / closing mechanism further includes an actuator that drives the valve body,
The sub-chamber internal combustion engine according to claim 8. The ignition unit is
A first electrode provided at the tip of the valve body;
A second electrode electrically insulated from the first electrode and provided on a wall surface of the auxiliary combustion chamber;
have,
The sub-chamber internal combustion engine according to claim 8 or 9. The ignition unit ignites a fresh air mixture in the auxiliary combustion chamber after the valve body closes the second communication path so that the first electrode approaches the second electrode.
The sub-chamber internal combustion engine according to claim 10. The second communication path is provided to guide at least one of the residual gas and the fresh air mixture in the pressure chamber to at least one of the wall surface of the sub-combustion chamber and the ignition unit.
The sub-chamber internal combustion engine according to any one of claims 1 to 11. A cooling mechanism for cooling at least one of the residual gas and the fresh air mixture in the pressure chamber;
The sub-chamber internal combustion engine according to any one of claims 1 to 12.

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