JP2006348809A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of surely bringing self-ignition of air fuel mixture gas at appropriate timing and burning the same with good fuel economy. <P>SOLUTION: This internal combustion engine 10 is provided with a recess part 30a and a partition valve 36 opening and closing an opening part of the recess part 30a on a cylinder head part 30. This internal combustion engine closes the opening part by the partition valve in compression stroke. Consequently, a combustion chamber 25 is partitioned into two independent hermetic spaces composed of a space 25a not adjoining a piston and a space 25b adjoining the piston. As a result, self-ignition of the air fuel mixture gas is brought since air fuel mixture gas in the space adjoining the piston is compressed more as compared with a case that a combustion chamber is not partitioned. Right after that, the internal combustion engine opens the opening part by the partition valve. Consequently, since unburned air fuel mixture gas in the space not adjoining the piston is heated by combustion gas produced in the space adjoining the piston, self-ignition of the air fuel mixture gas is brought and burned. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine that operates in a premixed compression self-ignition method in which a mixed gas containing air, fuel, and combustion gas is formed in a combustion chamber, and the mixed gas is self-ignited and combusted when compressed by a piston. About.

  2. Description of the Related Art Conventionally, as a method for operating an internal combustion engine, a premixed compression self-ignition method is known in which a mixed gas formed in a combustion chamber is compressed to self-ignite and burn within a very short period. If the internal combustion engine is operated by this premixed compression self-ignition method, the amount of NOx emissions is greater than that when the internal combustion engine is operated by the spark ignition method in which the mixed gas formed in the combustion chamber is ignited by the spark and burned. Is reduced and fuel efficiency is improved.

  By the way, in the internal combustion engine operated by the premixed compression self-ignition system, the timing at which the mixed gas self-ignites (self-ignition timing) has a strong correlation with the temperature of the mixed gas. On the other hand, the temperature of the mixed gas is likely to fluctuate with changes in the temperature of the outside air, the temperature of the combustion gas, etc., even if the operating state does not change. Therefore, the self-ignition timing is likely to fluctuate.

Therefore, the conventional internal combustion engine includes, as auxiliary compression means, a sub-cylinder that communicates with the combustion chamber above the combustion chamber, and a control piston that is reciprocated by hydraulic control in the sub-cylinder. Then, the mixed gas is secondarily compressed by driving the control piston at a predetermined timing (see, for example, Patent Document 1).
JP-A-10-196424

  In this conventional internal combustion engine, the temperature of the mixed gas rapidly rises to a temperature necessary for self-igniting the mixed gas at the predetermined timing due to the secondary compression of the mixed gas. Therefore, this conventional internal combustion engine can control the self-ignition timing to an appropriate timing.

  However, in order to rapidly increase the temperature of the mixed gas in the conventional internal combustion engine, it is necessary to compress all the mixed gas to be burned, so that the energy consumed to drive the control piston is reduced. There was a problem that the fuel consumption increased and the fuel consumption deteriorated.

  The present invention has been made in order to address the above-described problems, and one of the purposes is to allow the mixed gas to be self-ignited and burned at an appropriate timing with good fuel consumption. It is to provide an internal combustion engine. In order to achieve this object, an internal combustion engine according to the present invention includes a cylinder block in which a cylinder bore is formed, a cylinder head disposed at an upper portion of the cylinder block, and a piston that reciprocates in the cylinder bore, Premixed compression in which a mixed gas is formed in a combustion chamber formed by the wall surface of the cylinder bore, the lower surface of the cylinder head, and the top surface of the piston, and the formed mixed gas is self-ignited and combusted by the compression of the piston. Operate by self-ignition method.

The internal combustion engine according to the present invention comprises a non-piston space that does not contact the top surface of the piston from one space and a piston adjacent space that contacts the top surface of the piston by moving in the combustion chamber. Partition means for partitioning into two independent sealed spaces;
In the compression stroke, the partition means is driven so as to form the two sealed spaces composed of the piston non-adjacent space and the piston adjacent space, and the mixed gas self-ignites in the piston adjacent space to start combustion. Drive means for driving the partition means so as to form the one space in which the non-piston adjacent space and the piston adjacent space communicate with each other immediately after
Is provided.

  According to this, in the compression stroke, the combustion chamber is partitioned into two independent sealed spaces including a non-piston space that does not contact the top surface of the piston and a piston adjacent space that contacts the top surface of the piston. Thereby, since the volume of the non-piston space does not change even when the piston approaches the top dead center position, the mixed gas in the non-piston space is not compressed. On the other hand, when the piston approaches the top dead center position, the mixed gas in the space adjacent to the piston is compressed more largely than in the case where the combustion chamber is not partitioned.

  Therefore, after the combustion chamber is partitioned into two spaces, the temperature of the mixed gas in the piston adjacent space rapidly increases as time elapses. Thereby, even if the temperature of the mixed gas formed in the combustion chamber fluctuates, the timing at which the temperature of the mixed gas reaches a predetermined temperature (the temperature necessary for self-ignition of the mixed gas) greatly varies. Can be prevented. As a result, the mixed gas self-ignites and starts combustion at a timing when a predetermined time has elapsed after the combustion chamber is divided into two spaces. Immediately thereafter, the non-piston adjacent space and the piston adjacent space are brought into communication.

  Thereby, the combustion gas produced | generated by the combustion in piston adjacent space compresses the mixed gas (unburned mixed gas) which was unburned in the piston non-adjacent space. Further, the combustion gas and the unburned mixed gas are mixed. As a result, since the unburned mixed gas is heated, the unburned mixed gas can be self-ignited and burned.

  Thus, even if the temperature of the mixed gas fluctuates, all the mixed gas in the combustion chamber can be surely self-ignited and combusted at an appropriate timing. Furthermore, since the partition means is only driven as compared with the above-described prior art that compresses the entire mixed gas as a secondary, the consumed energy can be reduced.

In this case, the lower surface of the cylinder head is formed to include a recess having an opening that opens toward the top surface of the piston,
The partition means is preferably a partition valve that opens and closes the opening of the recess.

  According to this, the piston non-adjacent space and the piston adjacent space can be easily configured.

In this case, the partitioning valve is configured to open and close the opening by moving in a direction perpendicular to a surface forming the opening of the recess,
Further, the internal combustion engine is configured such that when the partition valve closes the opening of the recess, the partition valve moves away from the position of the partition valve when the partition valve is smaller than a predetermined distance. Passing through a gap formed between the remaining portion and the edge of the opening so as to form a gas flow from a part of the outer peripheral portion toward the remaining portion of the outer peripheral portion in the recess. It is preferable to provide a mask member configured to block the gas flow and allow the gas flow to pass through the gap when the moving distance is larger than the predetermined distance.

  As described above, the opening of the recess is opened by the partition valve at the timing immediately after the mixed gas in the piston adjacent space starts to burn. Thereby, the high-pressure gas generated by the combustion in the piston adjacent space starts to flow into the recess having a low pressure. At this time, if there is no mask member and a gas passage is formed between the entire outer periphery of the partition valve and the edge of the opening of the recess, the high-pressure gas flows into the outer periphery of the partition valve. Since they flow into the recess all at once at substantially the same flow rate from the whole, it is difficult to form a flow in a predetermined direction in the recess. For this reason, there is a problem that the gas burned in the recess is difficult to be discharged from the recess.

  On the other hand, if the mask member is provided, the mask member allows the partition valve to move to a predetermined distance after the opening of the recess starts to be opened by the partition valve until the movement distance of the partition valve reaches a predetermined distance. Gas passing through a gap formed between the remaining portion and the edge of the opening of the recess so that a gas flow from a part of the portion toward the remaining portion of the outer peripheral portion is formed in the recess. Is interrupted. As a result, a gas flow from a part of the outer peripheral portion of the partitioning valve toward the remaining portion of the outer peripheral portion is formed in the recess.

  Thereafter, when the opening of the recess is further opened by the partition valve, and the movement distance of the partition valve becomes larger than the predetermined distance, the remaining portion of the outer peripheral portion of the partition valve and the edge of the opening of the recess The flow of gas through the gap formed between the two is allowed. As a result, a gas flow is formed in which the gas flows from a part of the outer periphery of the partition valve into the recess and the gas flows out of the recess from the remaining part of the outer periphery by the gas flow formed above. Is done. As a result, the gas in the recess can be sufficiently discharged.

  In this case, it is preferable that the partition valve is configured to open the opening of the recess by moving toward the recess.

  As described above, the mixed gas self-ignites in the piston adjacent space before the piston non-adjacent space and starts combustion. Therefore, at the time immediately after the mixed gas starts combustion, the partition valve moves from the piston adjacent space (outside the recess) to the piston non-adjacent space (inside the recess) due to the pressure of the gas generated by the combustion in the piston adjacent space. Has been pushed towards.

  Therefore, as in the above configuration, the partition valve is configured to open the recess opening by moving toward the recess, thereby driving the partition valve when opening the recess opening. The force (driving force) can be reduced. As a result, the energy consumed for driving the partition valve can be reduced.

The partition valve opens the opening by moving toward the top surface of the piston in a direction perpendicular to the surface forming the opening of the recess, and It is configured to close the opening by moving toward the recess,
When the movement distance of the partition valve from the position of the partition valve when the partition valve closes the opening of the recess is smaller than a predetermined distance, from a part of the outer peripheral portion of the partition valve The flow of gas passing through the gap formed between the remaining portion and the edge of the opening is blocked so that the gas flow toward the remaining portion of the outer peripheral portion is formed in the recess. In addition, it is preferable to provide a mask member configured to allow the flow of gas passing through the gap when the moving distance is larger than the predetermined distance.

  As described above, when the mask member is provided, the opening of the recess is started to be opened by the partition valve until the movement distance of the partition valve reaches a predetermined distance. A gas flow from a part toward the remaining part of the outer periphery is formed in the recess. Thereafter, when the opening of the concave portion is further opened by the partition valve and the moving distance of the partition valve becomes larger than the predetermined distance, the gas flows from a part of the outer peripheral portion of the partition valve by the flow of the formed gas. A gas flow is formed in which the gas flows into the recess and flows out of the recess from the remaining portion of the outer periphery. As a result, the gas in the recess can be sufficiently discharged.

  By the way, the driving force for driving the partition valve must be greater than the drag force acting on the partition valve in the direction opposite to the drive direction of the partition valve. This drag is caused by the pressure acting on the surface of the compartment valve (mainly the difference between the pressure acting on the piston top surface and the pressure on the concave surface) and the gas flowing around the compartment valve. It is the sum of the resistance force (resistance) generated on the surface.

  On the other hand, immediately after the inflow of the combustion gas is started by opening the opening of the recess by the partitioning valve, the difference between the pressure acting on the piston top surface and the pressure acting on the recess surface is not increased. It is almost the same as the pressure difference before the valve. Furthermore, when the combustion gas flows from the outside of the recess to the inside of the recess, a large resistance force due to the gas flow is generated on the surface of the partition valve. Accordingly, the drag is maximized immediately after the inflow of combustion gas starts.

  By the way, when the mask member is provided, at the time immediately after the inflow of the combustion gas starts, the effective area for determining the magnitude of the resistance force caused by the gas flow when the combustion gas flows into the recess from the outside of the recess is This is smaller than the case where the mask member is not provided. Therefore, since the resistance force due to the gas flow generated by the flow of the combustion gas is reduced, the maximum value of the drag is also reduced. Thereby, the maximum driving force of the partition valve can be reduced.

  In this case, the opening of the concave portion may be formed on the lower surface of the cylinder head at a position in the lower surface of the cylinder head and facing the central portion of the piston.

The opening of the recess is circular,
Two circular openings communicating with each of the two intake ports, and the opening of the recess are located within the lower surface of the cylinder head constituting the combustion chamber, along the circumference of the cylinder bore and It is formed on the bottom surface of the cylinder head at successive positions,
It is preferable that one circular opening communicating with one exhaust port is formed on the lower surface of the cylinder head at the remaining portion of the lower surface of the cylinder head constituting the combustion chamber.

  According to this, three circular openings composed of two openings that communicate with the intake port and the openings of the recesses are positions within the lower surface of the cylinder head and along and along the circumference of the cylinder bore. Is formed on the lower surface of the cylinder head. Furthermore, a circular opening communicating with the exhaust port is formed in the remaining portion of the lower surface of the cylinder head.

  As a result, compared with the case where one of the three openings consisting of two openings communicating with the intake port and the opening of the recess is formed at a position facing the central portion of the piston, The area of the opening communicating with the port can be increased. As a result, exhaust resistance can be reduced, and fuel consumption can be improved.

(First embodiment)
Embodiments of an internal combustion engine according to the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of an internal combustion engine 10 according to the first embodiment. The internal combustion engine 10 is a multi-cylinder (4-cylinder) internal combustion engine that can be operated by a four-cycle premixed compression auto-ignition system. FIG. 1 shows only a cross section of a specific cylinder, but the other cylinders have the same configuration.

  The internal combustion engine 10 supplies air to the cylinder block portion 20 including a cylinder block, a cylinder block lower case, an oil pan, and the like, a cylinder head portion 30 fixed on the cylinder block portion 20, and the cylinder block portion 20. The intake system 40 and the exhaust system 50 for releasing the exhaust gas from the cylinder block unit 20 to the outside are included.

  The cylinder block portion 20 includes a hollow cylindrical cylinder (cylinder bore) 21 having a central axis, a substantially columnar piston 22, a connecting rod 23, and a crankshaft 24. The piston 22 reciprocates in the cylinder 21, and the reciprocating motion of the piston 22 is transmitted to the crankshaft 24 through the connecting rod 23, whereby the crankshaft 24 rotates. A bore wall surface of the cylinder 21 (wall surface of the cylinder bore), a top surface of the piston 22 (piston head), and a lower surface of the cylinder head portion 30 form a combustion chamber 25. Hereinafter, in the present specification, a direction along the central axis of the cylinder 21 toward the cylinder head portion 30 from the piston 22 is referred to as an upward direction, and the opposite direction is referred to as a downward direction.

  The cylinder head portion 30 communicates with an intake port 31 that communicates with the combustion chamber 25, an intake valve 32 that opens and closes the intake port 31, an intake valve drive mechanism 32 a that serves as an intake valve drive unit that drives the intake valve 32, and the combustion chamber 25. Exhaust port 33, exhaust valve 34 for opening and closing exhaust port 33, exhaust valve drive mechanism 34a as exhaust valve drive means for driving exhaust valve 34, fuel injection valve (fuel injection means) for directly injecting fuel into combustion chamber 25 35, a partitioning valve 36 as partitioning means and a cam mechanism 37 as drive means for driving the partitioning valve 36 are provided. The intake valve drive mechanism 32a and the exhaust valve drive mechanism 34a are connected to a drive circuit 38.

  As shown in FIG. 2, a concave portion 30 a having an opening that opens toward the top surface of the piston 22 is formed on the lower surface of the cylinder head portion 30. The recess 30 a has a cylindrical shape that is coaxial with the central axis of the cylinder 21. That is, the recess 30 a is disposed at a position in the lower surface of the cylinder head portion 30 and facing the central portion of the piston 22.

  The intake port 31 shown in FIG. 1 is formed so as to have circular openings at two locations in the lower surface of the cylinder head portion 30. Therefore, as shown in FIG. 3 when the lower surface of the cylinder head portion 30 is viewed from the combustion chamber 25 side, the cylinder head portion 30 is provided with two intake valves 32. Each intake valve 32 opens and closes the opening of each intake port 31. The intake port 31 communicates with the combustion chamber 25 when the opening is opened by the intake valve 32, and is blocked from the combustion chamber 25 when the opening is closed by the intake valve 32.

  The exhaust port 33 shown in FIG. 1 is formed so as to have circular openings at two locations in the lower surface of the cylinder head portion 30. Therefore, as shown in FIG. 3, the cylinder head portion 30 is provided with two exhaust valves 34. Each exhaust valve 34 opens and closes the opening of each exhaust port 33. The exhaust port 33 communicates with the combustion chamber 25 when the opening is opened by the exhaust valve 34, and is blocked from the combustion chamber 25 when the opening is closed by the exhaust valve 34.

  As shown in FIGS. 1 and 2, the fuel injection valve 35 is disposed on the side wall surface of the combustion chamber 25 on the intake valve 32 side. The fuel injection valve 35 includes a tip portion that injects fuel toward the substantially center of the combustion chamber 25, and the tip portion is exposed to the combustion chamber 25. The fuel in the fuel tank (not shown) is supplied to the fuel injection valve 35 by a fuel pressure adjusting means and a fuel pump (not shown).

  The intake system 40 shown in FIG. 1 has an intake manifold 41 communicating with the intake port 31, a surge tank 42 communicating with the intake manifold 41, and one end connected to the surge tank 42 to form an intake passage together with the intake manifold 41 and the surge tank 42. The intake duct 43, the air filter 44, the compressor 91a of the supercharger 91, the intercooler 45, and the throttle valve 46 disposed in that order in the intake duct 43 from the other end of the intake duct 43 to the downstream (surge tank 42). It has.

  The intercooler 45 is water-cooled and cools the air passing through the intake duct 43. The intercooler 45 discharges heat of the cooling water in the intercooler 45 to the atmosphere by a radiator and a circulation pump (not shown).

  The throttle valve 46 is rotatably supported by the intake duct 43 and is driven by a throttle valve actuator 46a so that the opening cross-sectional area of the intake passage is variable.

  The exhaust system 50 includes an exhaust pipe 51 including an exhaust manifold that communicates with the exhaust port 33 and forms an exhaust passage together with the exhaust port 33, a turbine 91b of a supercharger 91 disposed in the exhaust pipe 51, and a downstream of the turbine 91b. The exhaust pipe 51 is provided with a catalyst device 52.

  With such an arrangement, the turbine 91b of the supercharger 91 is rotated by the energy of the exhaust gas. Further, the turbine 91b is connected to the compressor 91a of the intake system 40 via a shaft. Thus, the compressor 91a of the intake system 40 rotates integrally with the turbine 91b to compress the air in the intake passage. That is, the supercharger 91 supercharges air to the internal combustion engine 10 using the energy of the exhaust gas.

  On the other hand, this system includes an electric control device 70. The electric control device 70 is a microcomputer including a CPU, a ROM, a RAM, an interface, and the like (all not shown). A crank position sensor 61 that detects an engine rotational speed NE from a rotational speed of the crankshaft 24 and an accelerator opening sensor 62 that detects an accelerator pedal operation amount Accp (not shown) are connected to the electric control device 70. . The electric control device 70 inputs each detection signal from these sensors. Further, the electric control device 70 is connected to the fuel injection valve 35, the drive circuit 38, and the throttle valve actuator 46a of each cylinder. The electric control device 70 sends drive signals to these.

  Here, the partition valve 36 and the cam mechanism 37 will be described in detail. As shown in FIG. 2, the partition valve 36 includes a handle portion 36a, a collar portion 36b, and an umbrella portion 36c. The handle portion 36a is a rod-shaped (columnar) member. The collar portion 36b is a disk-shaped member having a diameter larger than the diameter of the handle portion 36a. The collar portion 36b is fixed to the handle portion 36a at a position above the handle portion 36a and below the upper end portion of the handle portion 36a coaxially with the central axis of the handle portion 36a.

  The umbrella portion 36c is a substantially conical member having a top portion and a bottom surface. The diameter of the bottom surface of the umbrella part 36c is substantially the same as the diameter of the opening part of the recessed part 30a. The umbrella portion 36c is coaxial with the central axis of the handle portion 36a, and is fixed to the lower end portion of the handle portion 36a so that the top portion of the umbrella portion 36c contacts the lower end portion of the handle portion 36a.

  On the other hand, in the cylinder head portion 30, a spring accommodating space SP is formed above the recess 30a. The spring accommodating space SP is a cylindrical space that is coaxial with the central axis of the recess 30 a and has the same diameter as the collar portion 36 b of the partitioning valve 36. The partition valve 36 is slidably disposed on the cylinder head portion 30 so that the central axis of the handle portion 36a coincides with the central axis of the concave portion 30a and the collar portion 36b is positioned in the spring accommodating space SP. ing.

  A coiled spring SG is interposed between the wall surface that forms the bottom surface of the spring accommodating space SP and the lower surface of the collar portion 36b in the axially compressed state on the outer periphery of the handle portion 36a. Has been. Accordingly, the spring SG biases the partition valve 36 upward.

  The cam mechanism 37 includes a cam shaft 37a and a cam 37b. The camshaft 37a rotates 360 ° when the crankshaft 24 rotates 720 ° via a chain and a pulley (not shown). The camshaft 37a is arranged so that the rotational axis of the camshaft 37a is located on the central axis of the partitioning valve 36 (handle portion 36a).

  The cam 37b is connected to the camshaft 37a and rotates together with the camshaft 37a. The profile of the cam 37b (the shape of the cross section of the cam 37b by a plane orthogonal to the rotation axis of the cam 37b) is a shape composed of a circular base circle part and a cam peak part.

  The cam crest portion of the cam 37b is larger than the diameter of the base circle portion at a predetermined position (in this example, an arc portion having a central angle of about 340 °) in the outer edge portion of the base circle portion and about 340 °. A circular arc portion having a central angle is provided. The rotating shaft of the cam 37b is disposed so as to pass through the center of the base circle part and the cam peak part.

  With this configuration, the cam 37b is in contact with the upper end portion of the handle portion 36a of the partitioning valve 36, and pushes the partitioning valve 36 against the force urged by the spring SG. . Therefore, by rotating the cam 37b, the cam mechanism 37 moves the partition valve 36 in the central axis direction of the partition valve 36 (perpendicular to the surface forming the opening of the recess 30a). . As a result, the opening of the recess 30 a is opened and closed by the partition valve 36.

  Here, a change in the position of the partition valve 36 with respect to a change in the crank angle (movement of the piston 22) will be described with reference to FIG.

  First, when the crank angle is BTDC 40 °, as shown in FIG. 4A, the arc portion of the cam crest portion of the cam 37b comes into contact with the upper end portion (upper surface) of the handle portion 36a of the partitioning valve 36. ing. BTDC is a crank angle with the compression top dead center (TDC) as the origin and a positive value in the direction opposite to the rotation direction of the crankshaft 24. At this time, the partition valve 36 is pushed downward. Therefore, the umbrella part 36c of the partition valve 36 is separated from the edge part of the opening part of the recessed part 30a. Therefore, the combustion chamber 25 constitutes one space.

  Next, during the period (BTDC 40 ° to 30 °) until the crank angle reaches BTDC 30 ° after the crankshaft 24 rotates 10 ° (cam 37b rotates 5 °), the diameter of the cam crest portion of the cam 37b. The cam surface extending in the direction comes into contact with the upper end portion of the handle portion 36 a of the partitioning valve 36. At this time, the distance between the rotation shaft of the cam 37b and the upper end portion of the handle portion 36a of the partitioning valve 36 is abruptly reduced. That is, the partition valve 36 is rapidly pulled back upward (toward the recess 30a) by the spring SG.

  When the crank angle becomes BTDC 30 °, the base circle portion of the cam 37b comes into contact with the upper end portion of the handle portion 36a of the partitioning valve 36, as shown in FIG. At this time, since the umbrella portion 36c of the partition valve 36 is in contact with the edge of the opening of the recess 30a, the opening of the recess 30a is closed. As a result, one space constituting the combustion chamber 25 is partitioned into two independent sealed spaces composed of a piston non-adjacent space 25 a that does not contact the top surface of the piston 22 and a piston adjacent space 25 b that contacts the top surface of the piston 22. Is done.

  Thereafter, during the period (BTDC 30 ° to ATDC 10 °) until the crank angle reaches ATDC 10 ° when the crankshaft 24 further rotates 40 ° (cam 37b rotates 20 °), the base circle portion of the cam 37b is defined. It continues to contact the upper end of the handle portion 36a of the valve 36. ATDC is a crank angle with the compression top dead center (TDC) as the origin and the rotation direction of the crankshaft 24 as a positive value. Therefore, the distance between the rotating shaft of the cam 37b and the upper end of the handle portion 36a of the partitioning valve 36 is kept constant. As a result, the umbrella portion 36c of the partition valve 36 continues to contact the edge of the opening of the recess 30a (see FIG. 4C showing the time point of ATDC 10 °). Therefore, in the combustion chamber 25, the piston non-adjacent space 25a and the piston adjacent space 25b remain formed.

  Next, during the period until the crank angle reaches 20 ° ATDC (ATDC 10 ° to 20 °) when the crankshaft 24 further rotates 10 ° (cam 37b rotates 5 °), the diameter of the cam crest portion of the cam 37b. The cam surface extending in the direction comes into contact with the upper end portion of the handle portion 36 a of the partitioning valve 36. At this time, the distance between the rotating shaft of the cam 37b and the upper end portion of the handle portion 36a of the partitioning valve 36 increases rapidly. As a result, the partitioning valve 36 is suddenly pushed downward (toward the top surface of the piston 22) by the cam 37b.

  When the crank angle becomes ATDC 20 °, as shown in FIG. 4D, the arc portion of the cam crest portion of the cam 37b comes into contact with the upper end portion of the handle portion 36a of the partitioning valve 36. At this time, since the umbrella portion 36c of the partition valve 36 is separated from the edge of the opening of the recess 30a, the opening of the recess 30a is opened. As a result, the combustion chamber 25 is formed as one space where the piston non-adjacent space 25a and the piston adjacent space 25b communicate with each other.

  Thereafter, during a period until the crankshaft 24 rotates 660 ° and the crank angle reaches BTDC 40 ° (a period in which the cam 37b further rotates 330 °), the arc portion of the cam crest of the cam 37b It continues to contact the upper end of the handle 36a. Therefore, the distance between the rotating shaft of the cam 37b and the upper end of the handle portion 36a of the partitioning valve 36 is kept constant. As a result, the umbrella portion 36c of the partition valve 36 continues to be separated from the edge of the opening of the recess 30a.

  In this way, the cam valve 37 drives the partition valve 36 so as to form two sealed spaces composed of the piston non-adjacent space 25a and the piston adjacent space 25b at a predetermined timing before the crank angle reaches TDC. At the same time as the crank angle becomes TDC, the partition valve 36 is driven so as to form one space where the piston non-adjacent space 25a and the piston adjacent space 25b communicate with each other.

  A curve C1 indicated by a solid line in FIG. 5 shows a change in the pressure of air in the combustion chamber 25 with respect to the crank angle when only air is introduced into the combustion chamber 25 of the internal combustion engine 10 as described above. A curve C1a indicates a change in air pressure in the piston non-adjacent space 25a, and a curve C1b indicates a change in air pressure in the piston adjacent space 25b. A curved line C2 indicated by a dotted line shows a change in the pressure of air in the combustion chamber in the case of the prior art in which the combustion chamber is not partitioned.

  As indicated by the curve C1a, the pressure of the air in the piston non-adjacent space 25a becomes constant after the opening of the recess 30a is closed by the partition valve 36. On the other hand, as indicated by the curve C1b, the pressure of the air in the piston adjacent space 25b increases rapidly after the opening of the recess 30a is closed by the partition valve 36. Thereby, the temperature of the air in piston adjacent space 25b rises rapidly.

  Next, the operation of the internal combustion engine 10 configured as described above will be described. As shown in FIG. 6, the electric control device 70 of the internal combustion engine 10 operates the intake valve drive mechanism 32a, the exhaust valve drive mechanism 34a, and the fuel injection valve 35 at predetermined timings, respectively. Do the driving. That is, the electric control device 70 constitutes a self-ignition operation executing means.

  First, the electric control device 70 opens the exhaust valve 34 at the exhaust valve opening timing EO corresponding to the load of the internal combustion engine 10 by driving the exhaust valve drive mechanism 34a (see (1)). . Thereby, exhaust of the combustion gas produced | generated by the combustion in the last combustion cycle starts. Next, the electric control device 70 drives the exhaust valve drive mechanism 34a to close the exhaust valve 34 at the exhaust valve closing timing EC corresponding to the load of the internal combustion engine 10 (see (2)). . Thereby, exhaust ends.

  Thereafter, the electric control device 70 drives the intake valve drive mechanism 32a to open the intake valve 32 at the intake valve opening timing IO corresponding to the load of the internal combustion engine 10 (see (3)). . Thereby, inhalation is started. Thus, the negative overlap period which is a period from the time when exhaust ends to the time when intake starts is provided. As a result, combustion gas remains in the combustion chamber 25.

  Then, the electric control device 70 opens the fuel injection valve 35 so that the fuel at the initial and / or intermediate timing θinj of the intake stroke from the intake valve opening timing IO to the intake valve closing timing IC described later. Is injected (see (4)). The amount of fuel injected at this time is based on the load of the internal combustion engine 10 and the engine speed NE so that the air-fuel ratio of the mixed gas in the combustion chamber 25 becomes a very lean air-fuel ratio (ultra-lean air-fuel ratio). The amount is determined by The injected fuel is diffused in the combustion chamber 25 by the flow of air sucked into the combustion chamber 25.

  Next, the electric control device 70 drives the intake valve drive mechanism 32a to close the intake valve 32 at the intake valve closing timing IC corresponding to the load of the internal combustion engine 10 (see (5)). ). As a result, the intake is completed and the compression (compression stroke) of the mixed gas composed of air, fuel, and combustion gas is started. At this time, the partition valve 36 is pushed downward. Therefore, the umbrella part 36c of the partition valve 36 is separated from the edge part of the opening part of the recessed part 30a. Therefore, the combustion chamber 25 constitutes one space.

  Thereafter, when the crank angle becomes BTDC 30 °, the partition valve 36 is driven by the cam mechanism 37, and the opening of the recess 30a is closed by the partition valve 36 (see (6)). That is, one space constituting the combustion chamber 25 is partitioned into two independent sealed spaces composed of a piston non-adjacent space 25 a that does not contact the top surface of the piston 22 and a piston adjacent space 25 b that contacts the top surface of the piston 22. The

  When the piston 22 approaches the top dead center position, the pressure of the mixed gas in the piston non-adjacent space 25a does not change from the same pressure at the time when the combustion chamber 25 is partitioned, whereas in the piston adjacent space 25b. The pressure of the mixed gas increases rapidly. Thereby, the temperature of the mixed gas in piston adjacent space 25b rises rapidly. As a result, the mixed gas in the piston adjacent space 25b self-ignites and starts combustion.

  As described above, according to the internal combustion engine 10, the temperature of the mixed gas in the piston adjacent space 25 b is rapidly increased by driving the partition valve 36, and thus the mixed gas formed in the combustion chamber 25. Even when the temperature fluctuates, the timing at which the temperature of the mixed gas reaches a predetermined temperature (the temperature necessary for self-ignition of the mixed gas) can be prevented from greatly fluctuating. That is, the range of timing at which the mixed gas is self-ignited is narrower than in the case of the prior art in which the combustion chamber 25 is not partitioned (see FIG. 5).

  Next, when the crank angle becomes ATDC 10 °, the partition valve 36 is driven by the cam mechanism 37, and the opening of the recess 30a is opened by the partition valve 36 (see (7)). As a result, the piston non-adjacent space 25a and the piston adjacent space 25b are brought into communication at a timing immediately after the mixed gas self-ignites in the piston adjacent space 25b and starts combustion.

  Thereby, the combustion gas produced | generated by the combustion in the piston adjacent space 25b compresses the mixed gas (unburned mixed gas) which was unburned in the piston non-adjacent space 25a. Further, the combustion gas and the unburned mixed gas are mixed. As a result, since the unburned mixed gas is heated, the unburned mixed gas can be self-ignited and burned. In this way, even if the temperature of the mixed gas fluctuates, all the mixed gas in the combustion chamber 25 can be surely self-ignited and combusted at an appropriate timing. Further, since the partition valve 36 is only driven to control the timing at which the mixed gas self-ignites as compared with the above-described prior art which compresses all of the mixed gas in the combustion chamber as a secondary, it is consumed. Energy can be reduced.

  In this way, the internal combustion engine 10 is operated by the premixed compression self-ignition method.

  The triangular plot in FIG. 7 is a case where the basic compression ratio of the internal combustion engine 10 is configured to be 12 and the actual compression ratio is configured to be 16, and the operation as described above is performed. The change of the autoignition timing with respect to the compression initial temperature in the case where it is made is shown.

  The basic compression ratio is a ratio of the maximum value to the minimum value of the volume of the combustion chamber 25 when it is assumed that the partition valve 36 does not move while the opening of the recess 30a is opened. The actual compression ratio is the maximum value of the volume of the combustion chamber 25 with respect to the volume of the combustion chamber 25 (volume of the piston non-adjacent space 25a + volume of the piston adjacent space 25b) at the time when the opening of the recess 30a is closed by the partition valve 36. And the ratio of the maximum value to the minimum value of the volume of the piston adjacent space 25b (the volume of the piston adjacent space 25b at the time when the opening of the recess 30a is closed by the partition valve 36).

  The initial compression temperature is the temperature of the mixed gas when the intake valve 32 and the exhaust valve 34 are closed and the compression stroke in which the mixed gas in the combustion chamber 25 is compressed by the piston 22 is started. The self-ignition timing is a timing at which the mixed gas is self-ignited in the piston adjacent space 25b (a combustion chamber when the combustion chamber is not divided).

  The rhombus plot is an internal combustion engine configured so that the compression ratio (ratio of the maximum value to the minimum value of the volume of the combustion chamber) is 12, and the internal combustion engine in which the combustion chamber is not defined is a premixed compression auto-ignition system The above-mentioned change in the case of driving by is shown. The square plot shows the above-described change when the internal combustion engine configured to have a compression ratio of 16 and is operated with a premixed compression auto-ignition system in which the combustion chamber is not partitioned.

  Focusing on the range in which the compression initial temperature is a temperature from 450K to 500K, the internal combustion engine shown by the triangular plot as compared with the case of the internal combustion engine where the combustion chamber shown by the rhombus and square plot is not defined The variation amount of the self-ignition timing with respect to the compression initial temperature in 10 is small. That is, according to the internal combustion engine 10 according to the present embodiment, even if the temperature of the mixed gas fluctuates, the mixed gas is surely self-ignited and burned at an appropriate timing as compared with the case where the combustion chamber is not partitioned. It is understood that

  As described above, in the first embodiment of the internal combustion engine according to the present invention, in the compression stroke, the combustion chamber 25 is disposed between the piston non-adjacent space 25a that does not contact the top surface of the piston 22 from one space, and the top surface of the piston. It divides into two independent sealed spaces consisting of the adjacent piston adjacent space 25b. Thereby, the mixed gas in the piston adjacent space 25b is compressed more greatly when the piston approaches the top dead center position than in the case where the combustion chamber 25 is not partitioned. Therefore, after the combustion chamber 25 is partitioned into two spaces, the temperature of the mixed gas in the piston adjacent space 25b rapidly increases as time elapses.

  Thereby, the gas mixture self-ignites at the timing when a predetermined time has elapsed after the combustion chamber 25 is divided into two spaces, and starts combustion. Immediately thereafter, the first embodiment makes the non-piston space 25a and the piston space 25b communicate with each other. Thereby, the combustion gas produced | generated by the combustion in the piston adjacent space 25b heats the mixed gas which was unburned in the piston non-adjacent space 25a by compression and mixing, and self-ignites and burns the mixed gas. As a result, even if the temperature of the mixed gas fluctuates, all of the mixed gas in the combustion chamber 25 can be surely self-ignited and combusted at an appropriate timing.

(Second Embodiment)
Next, an internal combustion engine according to a second embodiment of the present invention will be described. The internal combustion engine according to the second embodiment is a mask member that blocks the flow of gas that passes through the gap formed between the outer peripheral portion of the partition valve 36 on the exhaust valve 34 side and the edge of the opening of the recess 30a. Is different from the internal combustion engine according to the first embodiment. Hereinafter, this difference will be mainly described.

  The internal combustion engine 10 includes a mask member 81 as shown in FIG. 8 in which the lower surface of the cylinder head 30 is viewed from the combustion chamber 25 side.

  The mask member 81 is a semi-annular member having an inner diameter that is the same as the diameter of the opening of the recess 30a when viewed from the front. The mask member 81 is disposed and fixed on the lower surface of the cylinder head portion 30 at the outer periphery of the opening of the recess 30a on the exhaust valve 34 side so that the center coincides with the central axis of the recess 30a. As shown in FIG. 9, the mask member 81 has a thickness in the central axis direction of the recess 30 a that increases from the end portion toward the central portion, and the thickness of the central portion is equal to the axial movement distance of the partition valve 36. It is formed to be half.

  With such a configuration, the movement distance of the partition valve 36 from the position of the partition valve 36 when the partition valve 36 closes the opening of the recess 30a is a predetermined distance (half the maximum value of the movement distance). ) Is smaller, the outer edge portion of the partition valve 36 on the exhaust valve 34 side is in contact with the inner wall of the mask member 81. Therefore, on the exhaust valve 34 side of the partition valve 36, the gas flow between the inside of the recess 30a and the outside of the recess 30a is substantially blocked (see FIG. 9B). On the other hand, when the moving distance is larger than the predetermined distance, the outer edge portion is separated from the inner wall of the mask member 81. Therefore, the gas flow between the inside of the recess 30a and the outside of the recess 30a is allowed also on the exhaust valve 34 side of the partition valve 36 (see FIG. 9C).

  Next, the operation of the internal combustion engine 10 configured as described above will be described. As in the first embodiment, the electric control device 70 of the internal combustion engine 10 operates the intake valve drive mechanism 32a, the exhaust valve drive mechanism 34a, and the fuel injection valve 35 at predetermined timing (see FIG. 6). ). Thus, a mixed gas composed of air, fuel, and combustion gas is formed in the combustion chamber 25 at the time when the intake valve 32 is closed (see (5)).

  Next, as the piston 22 moves toward the top dead center position, the mixed gas is compressed. When the crank angle reaches BTDC 30 °, as described above, the partition valve 36 is driven by the cam mechanism 37, and the opening of the recess 30a is closed by the partition valve 36 (see (6)). Thereby, two independent sealed spaces composed of the piston non-adjacent space 25a and the piston adjacent space 25b are formed.

  When the piston 22 approaches the top dead center position, as described above, the temperature of the mixed gas in the piston adjacent space 25b rapidly rises, and the mixed gas self-ignites and starts combustion. Thereafter, when the crank angle becomes ATDC 10 °, the partition valve 36 is driven by the cam mechanism 37, and the partition valve 36 is moved downward (the top surface side of the piston 22) (see (7)). .

  When the opening of the recess 30a starts to be opened by the partition valve 36, the combustion gas generated by the combustion in the piston adjacent space 25b starts to flow into the recess 30a. At this time, the moving distance of the partition valve 36 is smaller than the predetermined distance. Therefore, the gas flow is cut off on the exhaust valve 34 side of the partition valve 36 (see FIG. 9B). That is, the combustion gas flows only from the intake valve 32 side of the partitioning valve 36.

  Therefore, the effective area for determining the magnitude of the resistance force caused by the gas flow when the combustion gas flows from the outside of the recess 30 a into the recess 30 a is smaller than that in the case where the mask member 81 is not provided. As a result, the resistance force due to the gas flow generated on the surface of the partition valve 36 by the combustion gas flowing from the outside of the recess 30 a into the recess 30 a becomes smaller than that in the case where the mask member 81 is not provided. As a result, the maximum driving force required to drive the partition valve 36 can be reduced.

  Furthermore, since the gas flow is blocked on the exhaust valve 34 side of the partition valve 36, the gas flow from the outer peripheral portion on the intake valve 32 side to the outer peripheral portion on the exhaust valve 34 side of the partition valve 36. It is formed in the recess 30a (see FIG. 9B).

  Next, when the partition valve 36 moves further downward, the moving distance of the partition valve 36 becomes larger than the predetermined distance. Therefore, the gas flow between the inside of the recess 30a and the outside of the recess 30a is allowed also on the exhaust valve 34 side of the partitioning valve 36. At this point, the pressure difference between the inside of the recess 30a and the outside of the recess 30a is sufficiently small. Therefore, gas flows into the recess 30a from the outer periphery of the partition valve 36 on the intake valve 32 side by the gas flow that has already been formed, and the gas is recessed from the outer periphery of the partition valve 36 on the exhaust valve 34 side. A flow of gas flowing out of 30a is formed. As a result, the gas in the recess 30a can be sufficiently discharged.

  In addition, the unburned mixed gas in the piston non-adjacent space 25a is heated by compression and mixing by the combustion gas generated by the combustion in the piston adjacent space 25b, so that the mixed gas self-ignites. Burn. As a result, even if the temperature of the mixed gas fluctuates, all of the mixed gas in the combustion chamber 25 can be surely self-ignited and combusted at an appropriate timing. Further, since the partition valve 36 is only driven to control the timing at which the mixed gas self-ignites as compared with the above-described prior art which compresses all of the mixed gas in the combustion chamber as a secondary, it is consumed. Energy can be reduced.

  As described above, the second embodiment of the internal combustion engine according to the present invention passes through the gap formed between the outer peripheral portion of the partition valve 36 on the exhaust valve 34 side and the edge of the opening of the recess 30a. A mask member 81 is provided to block the flow of gas. According to this, the gas flow is blocked by the mask member 81 until the moving distance of the partition valve 36 reaches a predetermined distance after the opening of the recess 30a starts to be opened by the partition valve 36. A gas flow from the outer peripheral portion (a part of the outer peripheral portion) on the intake valve 32 side of the working valve 36 toward the outer peripheral portion (the remaining portion of the outer peripheral portion) on the exhaust valve 34 side is formed in the recess 30a.

  Thereafter, when the movement distance of the partition valve 36 becomes larger than the predetermined distance, it passes through a gap formed between the outer peripheral portion of the partition valve 36 on the exhaust valve 34 side and the edge of the opening of the recess 30a. Gas flow is allowed. Accordingly, the gas flows into the recess 30a from the outer peripheral portion of the partition valve 36 on the intake valve 32 side by the gas flow formed as described above, and flows out of the recess 30a from the outer peripheral portion on the exhaust valve 34 side. A gas flow is formed. As a result, the gas in the recess 30a can be sufficiently discharged.

(Modification of the second embodiment)
Next, a modification of the second embodiment will be described. As shown in FIG. 10, this modification is the second only in that a mask member 82, which replaces the mask member 81 of the second embodiment, is disposed and fixed on the upper surface of the umbrella portion 36c of the partitioning valve 36. This is different from the embodiment. Therefore, such differences will be described below.

  The mask member 82 is a semi-annular member having an outer diameter that is the same as the diameter of the side wall surface that forms the recess 30a when viewed from the front. The mask member 82 is disposed and fixed on the upper surface of the umbrella portion 36c of the partition valve 36 on the exhaust valve 34 side so that the center coincides with the central axis of the recess 30a. As shown in FIG. 10, the mask member 82 increases in thickness in the central axis direction of the recess 30a from the end portion toward the central portion, and the thickness of the central portion is equal to the axial movement distance of the partition valve 36. It is formed to be half.

  With such a configuration, the movement distance of the partition valve 36 from the position of the partition valve 36 when the partition valve 36 closes the opening of the recess 30a is a predetermined distance (half the maximum value of the movement distance). ) Is smaller, the outer wall of the mask member 82 is in contact with the side wall surface forming the recess 30a. Therefore, on the exhaust valve 34 side of the partition valve 36, the gas flow between the recess 30a and the outside of the recess 30a is blocked (see FIG. 10B). On the other hand, when the moving distance is larger than the predetermined distance, the outer wall is separated from the side wall surface forming the recess 30a. Therefore, the gas flow between the inside of the recess 30a and the outside of the recess 30a is allowed also on the exhaust valve 34 side of the partition valve 36 (see FIG. 10C).

  According to this, as in the second embodiment, from the outer peripheral portion (a part of the outer peripheral portion) of the partition valve 36 on the intake valve 32 side to the outer peripheral portion (the remaining portion of the outer peripheral portion) on the exhaust valve 34 side. A flowing gas flow is formed in the recess 30a. As a result, the gas in the recess 30a can be sufficiently discharged.

(Third embodiment)
Next, an internal combustion engine according to a third embodiment of the present invention will be described. The internal combustion engine 10 according to the third embodiment is configured such that the opening of the recess is opened by the partition valve 36 moving (upward) into the recess and the exhaust of the partition valve 36. It differs from the internal combustion engine 10 according to the first embodiment in that it includes a mask member that blocks the flow of gas that passes through the gap formed between the outer peripheral portion on the valve 34 side and the edge of the opening of the recess. is doing. Hereinafter, this difference will be mainly described.

  As shown in FIG. 11, the cylinder head portion 30 provided in the internal combustion engine 10 is formed with a recess 83 in place of the recess 30a of the first embodiment. The recess 83 includes a small-diameter cylindrical space and a large-diameter cylindrical space that are coaxial with the central axis of the cylinder 21. The lower end portion of the side wall surface that forms the small-diameter cylindrical space is open to the lower surface of the cylinder head portion 30. The upper part of the small diameter cylindrical space is connected to the large diameter cylindrical space.

  Furthermore, the partition valve 36 provided in the internal combustion engine 10 includes an umbrella portion 84 that replaces the umbrella portion 36c of the first embodiment. The umbrella portion 84 is a substantially conical member having a top portion and a bottom surface. The diameter of the bottom surface of the umbrella portion 84 is substantially the same as the diameter of the opening portion of the recess 83 (the diameter of the lower end portion of the side wall surface forming the small-diameter cylindrical space). The umbrella portion 84 is coaxial with the central axis of the handle portion 36a, and is fixed to the lower end portion of the handle portion 36a so that the top portion of the umbrella portion 84 is in contact with the lower end portion of the handle portion 36a.

  The cam mechanism 37 included in the internal combustion engine 10 includes a cam 85 that replaces the cam 37 of the first embodiment. The cam 85 is connected to the camshaft 37a and rotates together with the camshaft 37a. The profile of the cam 85 (the shape of the cross section of the cam 85 by a plane orthogonal to the rotation axis of the cam 37b) is a shape composed of a circular base circle portion and a cam peak portion.

  The cam peak portion of the cam 85 is in a radial direction with respect to the rotation axis of the cam 85 at a predetermined position (in this example, an arc portion having a central angle of about 20 °) of the outer edge portion of the base circle portion. It protrudes. The rotation axis of the cam 85 is disposed so as to pass through the center of the base circle portion.

  With such a configuration, during the period in which the crank angle changes from BTDC 30 ° to ATDC 10 ° (period in which the crankshaft 24 rotates by 40 ° (cam 85 rotates 20 °)), the top of the cam crest portion of the cam 85 is for partitioning. It abuts on the upper end of the handle 36a of the valve 36. Therefore, during this period, the cam mechanism 37 pushes the partition valve 36 downward. As a result, the umbrella portion 84 of the partition valve 36 contacts the side wall surface forming the small-diameter cylindrical space of the recess 83, and the opening of the recess 83 is closed by the partition valve 36. That is, one space constituting the combustion chamber 25 is partitioned into two independent sealed spaces composed of a piston non-adjacent space 25 a that does not contact the top surface of the piston 22 and a piston adjacent space 25 b that contacts the top surface of the piston 22. The

  On the other hand, during a period in which the crank angle changes from ATDC 10 ° to BTDC 30 ° (period in which the crankshaft 24 rotates 680 ° (cam 85 340 °)), the base circle portion of the cam 85 is the handle portion 36a of the partition valve 36. It abuts on the upper end of the. Accordingly, during this period, the partitioning valve 36 is pulled back upward by the spring SG, and moves toward (in the upward direction) into the recess 83. Thereby, the umbrella portion 84 of the partition valve 36 is separated from the side wall surface forming the small-diameter cylindrical space of the recess 83, and the opening of the recess 83 is opened by the partition valve 36. That is, the combustion chamber 25 constitutes one space.

  In this way, the cam valve 37 allows the partition valve 36 to form two sealed spaces composed of the piston non-adjacent space 25a and the piston adjacent space 25b at a predetermined timing before the crank angle reaches TDC. In addition to being driven, the partition valve 36 is driven so as to form one space where the piston non-adjacent space 25a and the piston adjacent space 25b communicate with each other at a timing immediately after the crank angle becomes TDC.

  In addition, the internal combustion engine 10 includes a mask member 86.

  The mask member 86 has an inner diameter that is the same as the diameter of the upper end portion of the side wall surface that forms the small-diameter cylindrical space of the recess 83 and the same diameter as the side wall surface that forms the large-diameter cylindrical space of the recess 83 when viewed from the front. A semi-annular member having an outer diameter. The mask member 86 is disposed and fixed on the exhaust valve 34 side of the bottom surface forming the large-diameter cylindrical space of the recess 83 so that the center coincides with the central axis of the recess 83. As shown in FIG. 12, the mask member 86 has a thickness in the central axis direction of the concave portion 83 that increases from the end portion toward the central portion, and the thickness of the central portion is equal to the axial movement distance of the partition valve 36. It is formed to be half.

  With such a configuration, the movement distance of the partition valve 36 from the position of the partition valve 36 when the partition valve 36 closes the opening of the recess 83 is a predetermined distance (half the maximum value of the movement distance). ), The outer edge of the partition valve 36 on the exhaust valve 34 side is in contact with the inner wall of the mask member 86. Therefore, on the exhaust valve 34 side of the partitioning valve 36, the gas flow between the recess 83 and the outside of the recess 83 is blocked (see FIG. 12B). On the other hand, when the moving distance is larger than the predetermined distance, the outer edge portion is separated from the inner wall of the mask member 86. Therefore, the gas flow between the inside of the recessed portion 83 and the outside of the recessed portion 83 is allowed also on the exhaust valve 34 side of the partitioning valve 36 (see FIG. 12C).

  Next, the operation of the internal combustion engine 10 configured as described above will be described. As in the first embodiment, the electric control device 70 of the internal combustion engine 10 operates the intake valve drive mechanism 32a, the exhaust valve drive mechanism 34a, and the fuel injection valve 35 at predetermined timing (see FIG. 6). ). Thus, a mixed gas composed of air, fuel, and combustion gas is formed in the combustion chamber 25 at the time when the intake valve 32 is closed (see (5)).

  Next, as the piston 22 moves toward the top dead center position, the mixed gas is compressed. When the crank angle reaches BTDC 30 °, the partition valve 36 is driven by the cam mechanism 37 as described above, and the opening of the recess 83 is closed by the partition valve 36 (see (6)). Thereby, two independent sealed spaces composed of the piston non-adjacent space 25a and the piston adjacent space 25b are formed.

  When the piston 22 approaches the top dead center position, as described above, the temperature of the mixed gas in the piston adjacent space 25b rapidly rises, and the mixed gas self-ignites and starts combustion. Thereafter, when the crank angle becomes ATDC 10 °, the partition valve 36 is driven by the cam mechanism 37, and the partition valve 36 is moved upward (see (7)).

  As described above, the mixed gas self-ignites in the piston adjacent space 25b before the piston non-adjacent space 25a and starts to burn. Therefore, at the time immediately after the mixed gas starts combustion, the partition valve 36 is moved from the piston adjacent space 25b (outside the recess 83) to the piston non-adjacent space by the pressure of the gas generated by the combustion in the piston adjacent space 25b. It is pushed toward 25a (in the recess 83).

  Therefore, the force for driving the partition valve 36 can be reduced by opening the opening of the recess 83 by moving the partition valve 36 into the recess 83. As a result, the energy consumed to drive the partition valve 36 can be reduced.

  When the opening of the recess 83 starts to be opened by the partition valve 36, the combustion gas generated by the combustion in the piston adjacent space 25b starts to flow into the recess 83. At this time, the moving distance of the partition valve 36 is smaller than the predetermined distance. Therefore, as in the second embodiment, the gas flow is blocked on the exhaust valve 34 side of the partition valve 36 (see FIG. 12B). That is, the combustion gas flows only from the intake valve 32 side of the partitioning valve 36.

  Accordingly, since the gas flow is blocked on the exhaust valve 34 side of the partition valve 36, the gas flow from the outer peripheral portion on the intake valve 32 side to the outer peripheral portion on the exhaust valve 34 side of the partition valve 36. It is formed in the recess 83 (see FIG. 12B).

  Next, when the partition valve 36 moves further upward, the moving distance of the partition valve 36 becomes larger than the predetermined distance. Therefore, the gas flow between the inside of the recess 83 and the outside of the recess 83 is allowed also on the exhaust valve 34 side of the partition valve 36. At this time, the pressure difference between the inside of the recess 83 and the outside of the recess 83 is sufficiently small. Therefore, the gas flows from the outer peripheral portion on the intake valve 32 side of the partition valve 36 into the concave portion 83 by the gas flow that has already been formed, and the gas flows into the concave portion 83 from the outer peripheral portion on the exhaust valve 34 side of the partition valve 36. A flow of gas flowing out is formed. As a result, the gas in the recess 83 can be sufficiently discharged.

  In addition, the unburned mixed gas (unburned mixed gas) in the piston non-adjacent space 25a is compressed by the combustion gas generated by the combustion in the piston adjacent space 25b. Further, the unburned mixed gas and the burned gas are mixed. Thereby, since the unburned mixed gas is heated, the unburned mixed gas self-ignites and burns. As a result, even if the temperature of the mixed gas fluctuates, all the mixed gas in the combustion chamber 25 can be surely self-ignited and combusted at an appropriate timing. Further, since the partition valve 36 is only driven to control the timing at which the mixed gas self-ignites as compared with the above-described prior art which compresses all of the mixed gas in the combustion chamber as a secondary, it is consumed. Energy can be reduced.

  As described above, the third embodiment of the internal combustion engine according to the present invention is configured to open the opening of the recess 83 by moving the partition valve 36 into the recess 83. Thereby, the force for driving the partition valve 36 can be reduced. As a result, the energy consumed to drive the partition valve 36 can be reduced.

(Modification of the third embodiment)
Next, a modification of the third embodiment will be described. As shown in FIG. 13, this modification is the third embodiment only in that a mask member 87 that replaces the mask member 86 of the third embodiment is disposed and fixed on the lower surface of the umbrella portion 84 of the partition valve 36. This is different from the embodiment. Therefore, such differences will be described below.

  The mask member 87 is a semi-annular member having an outer diameter that is the same as the diameter of the lower end portion of the side wall surface that forms the small-diameter cylindrical space of the recess 83 when viewed from the front. The mask member 87 is disposed and fixed on the lower surface of the umbrella portion 84 of the partition valve 36 on the exhaust valve 34 side so that the center coincides with the central axis of the recess 83. As shown in FIG. 13, the mask member 87 has a thickness in the central axis direction of the recess 83 that increases from the end portion toward the central portion, and the thickness of the central portion is equal to the axial movement distance of the partition valve 36. It is formed to be half.

  With such a configuration, the movement distance of the partition valve 36 from the position of the partition valve 36 when the partition valve 36 closes the opening of the recess 83 is a predetermined distance (half the maximum value of the movement distance). ), The outer wall of the mask member 87 is in contact with the side wall surface that forms the small-diameter cylindrical space of the recess 83. Therefore, on the exhaust valve 34 side of the partitioning valve 36, the gas flow between the inside of the recess 83 and the outside of the recess 83 is blocked (see FIG. 13B). On the other hand, when the moving distance is larger than the predetermined distance, the outer wall is separated from the side wall surface. Therefore, the gas flow between the inside of the recessed portion 83 and the outside of the recessed portion 83 is allowed also on the exhaust valve 34 side of the partitioning valve 36 (see FIG. 13C).

  According to this, as in the third embodiment, from the outer peripheral portion (a part of the outer peripheral portion) of the partition valve 36 on the intake valve 32 side to the outer peripheral portion (the remaining portion of the outer peripheral portion) on the exhaust valve 34 side. A flowing gas flow is formed in the recess 83. As a result, the gas in the recess 83 can be sufficiently discharged.

(Fourth embodiment)
Next, an internal combustion engine according to a fourth embodiment of the present invention will be described. The internal combustion engine according to the fourth embodiment includes each of the above embodiments in that the opening portion of the recess 30a, the opening portion communicating with the intake port 31 and the opening portion communicating with the exhaust port 33 are provided in different modes. It differs from the internal combustion engine which concerns on a form. Hereinafter, this difference will be mainly described.

  The internal combustion engine 10 includes a cylinder head portion 101 that replaces the cylinder head portion 30 in each of the above embodiments. As shown in FIG. 14 when the lower surface of the cylinder head portion 101 is viewed from the combustion chamber 25 side, the lower surface of the cylinder head portion 101 is formed with a recess 30a having an opening that opens toward the top surface of the piston 22. ing. The recess 30a has a cylindrical shape with the axis parallel to the center axis of the cylinder 21 as the center axis. The opening of the recess 30 a is located at a position within the lower surface of the cylinder head portion 101 and along the peripheral portion of the bore of the cylinder 21.

  The cylinder head portion 101 is formed with two intake ports 31 and one exhaust port 102.

  The intake port 31 is formed to have circular openings at two locations in the lower surface of the cylinder head portion 101. The opening portion of the intake port 31 is disposed at a position along the peripheral portion of the bore of the cylinder 21 and continuous with the opening portion of the recess 30a. The cylinder head portion 101 is provided with two intake valves 32. Each intake valve 32 opens and closes the opening of each intake port 31. The intake port 31 communicates with the combustion chamber 25 when the opening is opened by the intake valve 32, and is blocked from the combustion chamber 25 when the opening is closed by the intake valve 32.

  The exhaust port 102 is formed so as to have a circular opening having a larger diameter than the opening of the intake port 31 at one position in the lower surface of the cylinder head portion 101. The opening portion of the exhaust port 102 is disposed in the remaining portion of the lower surface of the cylinder head portion 101. The cylinder head portion 101 is provided with one exhaust valve 103. The exhaust valve 103 opens and closes the opening of the exhaust port 102. The exhaust port 102 communicates with the combustion chamber 25 when the opening is opened by the exhaust valve 103, and is blocked from the combustion chamber 25 when the opening is closed by the exhaust valve 103.

  With such a configuration, when one of the three openings composed of the two openings communicating with the intake port 31 and the opening of the recess 30a is formed at a position facing the central portion of the piston 22. As compared with the above, the area of the opening communicating with the exhaust port 102 can be increased. As a result, exhaust resistance can be reduced, and fuel consumption can be improved.

  As described above, in the fourth embodiment of the internal combustion engine according to the present invention, the three circular openings including the two openings communicating with the intake port 31 and the opening of the recess 30a are formed on the lower surface of the cylinder head 101. The cylinder head portion 101 is formed on the lower surface of the cylinder head portion 101 at a position along and along the peripheral portion of the bore of the cylinder 21. In the fourth embodiment, a circular opening communicating with the exhaust port 102 is formed in the remaining portion of the lower surface of the cylinder head 101. As a result, the area of the opening communicating with the exhaust port 102 can be increased. As a result, exhaust resistance can be reduced, and fuel consumption can be improved.

  As described above, according to the internal combustion engine according to each embodiment of the present invention, the self-ignition timing is controlled to an appropriate timing by opening and closing the opening of the recess by the partition valve 36 at a predetermined timing. can do.

  In addition, this invention is not limited to said each embodiment, A various modification can be employ | adopted within the scope of the present invention. For example, the supercharger 91 in each of the above embodiments is a turbocharger, but may be a mechanical supercharger (supercharger).

  In each of the above embodiments, the partition valve 36 is driven by the cam mechanism 37, but the partition valve 36 may be driven by an electromagnetic mechanism or a hydraulic mechanism.

  Further, in each of the above embodiments, the operation by the premixed compression auto-ignition method and the operation by the spark ignition method in which the mixed gas is ignited and burned by the spark generated by the spark plug according to the load of the internal combustion engine and the engine speed. It may be configured to perform switching.

1 is a schematic view of an internal combustion engine according to a first embodiment of the present invention. FIG. 2 is a partially enlarged sectional view in the vicinity of a combustion chamber of the internal combustion engine shown in FIG. 1. It is the schematic which looked at the lower surface of the cylinder head part shown in FIG. 1 from the combustion chamber side. It is the figure which showed typically the change of the combustion chamber shown in FIG. 1 with respect to the crank angle. It is the figure which showed typically the change of the pressure of the air in a combustion chamber with respect to a crank angle. FIG. 2 is an explanatory diagram conceptually showing opening / closing timings and fuel injection timings of an intake valve, an exhaust valve, and a partition valve of a cylinder having the internal combustion engine shown in FIG. 1. It is the graph which showed the change of the self-ignition timing with respect to compression initial temperature. It is the schematic which looked at the lower surface of the cylinder head part with which the internal combustion engine which concerns on 2nd Embodiment of this invention is provided from the combustion chamber side. It is explanatory drawing which showed notionally the flow of gas when the valve for divisions shown in FIG. 8 opens. It is explanatory drawing which showed notionally the flow of gas when the valve for division with which the internal combustion engine which concerns on the modification of 2nd Embodiment of this invention is provided opens. It is the figure which showed typically the valve for a division and the cam mechanism with which the internal combustion engine which concerns on 3rd Embodiment of this invention is provided. It is explanatory drawing which showed notionally the flow of gas when the valve for divisions shown in FIG. 11 opens. It is explanatory drawing which showed notionally the gas flow when the valve for division with which the internal combustion engine which concerns on the modification of 3rd Embodiment of this invention is provided opens. It is the schematic which looked at the lower surface of the cylinder head part with which the internal combustion engine which concerns on 4th Embodiment of this invention is provided from the combustion chamber side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 20 ... Cylinder block part, 21 ... Cylinder, 22 ... Piston, 23 ... Connecting rod, 24 ... Crankshaft, 25 ... Combustion chamber, 25a ... Piston non-adjacent space, 25b ... Piston adjacent space, 30 ... Cylinder head , 30a ... recess, 31 ... intake port, 32 ... intake valve, 32a ... intake valve drive mechanism, 33 ... exhaust port, 34 ... exhaust valve, 34a ... exhaust valve drive mechanism, 35 ... fuel injection valve, 36 ... for compartment Valve, 36a ... handle part, 36b ... collar part, 36c ... umbrella part, 37 ... cam mechanism, 37a ... cam shaft, 37b ... cam, 38 ... drive circuit, 61 ... crank position sensor, 62 ... accelerator opening sensor, 70 ... Electric control device, 81, 82 ... Mask member, 83 ... Recess, 84 ... Umbrella part, 85 ... Cam, 86, 87 ... Mask member, 101 ... Cylinder head part, 10 ... exhaust port, 103 ... exhaust valves, SG ... spring, SP ... spring housing space.

Claims (7)

A cylinder block in which a cylinder bore is formed; a cylinder head disposed at an upper portion of the cylinder block; and a piston that reciprocates in the cylinder bore; and at least a wall surface of the cylinder bore, a lower surface of the cylinder head, and the piston An internal combustion engine that operates in a premixed compression self-ignition method in which a gas mixture is formed in a combustion chamber constituted by a top surface and the formed gas mixture is self-ignited and combusted by compression.
By moving in the combustion chamber, the combustion chamber is divided into two independent sealed spaces including a piston non-adjacent space that does not contact the top surface of the piston and a piston adjacent space that contacts the top surface of the piston. Partitioning means for partitioning;
In the compression stroke, the partition means is driven so as to form the two sealed spaces composed of the piston non-adjacent space and the piston adjacent space, and the mixed gas self-ignites in the piston adjacent space to start combustion. Drive means for driving the partition means so as to form the one space in which the non-piston adjacent space and the piston adjacent space communicate with each other immediately after
An internal combustion engine. The internal combustion engine according to claim 1,
The lower surface of the cylinder head is formed to include a recess having an opening that opens toward the top surface of the piston.
The internal combustion engine, wherein the partition means is a partition valve that opens and closes an opening of the recess. An internal combustion engine according to claim 2,
The partition valve is configured to open and close the opening by moving in a direction perpendicular to the surface forming the opening of the recess,
When the movement distance of the partition valve from the position of the partition valve when the partition valve closes the opening of the recess is smaller than a predetermined distance, from a part of the outer peripheral portion of the partition valve The flow of gas passing through the gap formed between the remaining portion and the edge of the opening is blocked so that the gas flow toward the remaining portion of the outer peripheral portion is formed in the recess. An internal combustion engine comprising a mask member configured to allow the flow of gas through the gap when the moving distance is greater than the predetermined distance. The internal combustion engine according to claim 2 or claim 3,
The internal combustion engine configured to open the opening of the recessed portion by moving the partitioning valve toward the recessed portion. An internal combustion engine according to claim 2,
The partition valve opens the opening by moving toward the top surface of the piston in a direction perpendicular to the surface forming the opening of the recess, and the recess in the vertical direction. Configured to close the opening by moving toward
When the movement distance of the partition valve from the position of the partition valve when the partition valve closes the opening of the recess is smaller than a predetermined distance, from a part of the outer peripheral portion of the partition valve The flow of gas passing through the gap formed between the remaining portion and the edge of the opening is blocked so that the gas flow toward the remaining portion of the outer peripheral portion is formed in the recess. An internal combustion engine comprising a mask member configured to allow the flow of gas through the gap when the moving distance is greater than the predetermined distance. The internal combustion engine according to any one of claims 2 to 5,
An internal combustion engine in which the opening of the concave portion is formed on the lower surface of the cylinder head at a position within the lower surface of the cylinder head and facing the central portion of the piston. The internal combustion engine according to any one of claims 2 to 5,
The opening of the recess is circular,
Two circular openings communicating with each of the two intake ports, and the opening of the recess are located within the lower surface of the cylinder head constituting the combustion chamber, along the circumference of the cylinder bore and It is formed on the bottom surface of the cylinder head at successive positions,
An internal combustion engine in which one circular opening communicating with one exhaust port is formed on the lower surface of the cylinder head at the remaining portion of the lower surface of the cylinder head constituting the combustion chamber.

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