JP2019105175A - Internal combustion engine - Google Patents

Abstract

To provide an internal combustion engine capable of improving heat efficiency while keeping cleaning efficiency of a catalyst.SOLUTION: An internal combustion engine 2 includes a first cylinder 4, a second cylinder 6, an air-fuel ratio detection portion 7, a first control portion 8, and knock adjustment means 10. The air-fuel ratio detection portion 7 detects an air-fuel ratio of an exhaust gas discharged from the first cylinder 4 and the second cylinder 6. The first control portion 8 controls a fuel injection valve 52 of the first cylinder 4 and a fuel injection valve 52 of the second cylinder 6 so as to form a rich region richer than the air-fuel ratio of the first cylinder 4, in a combustion chamber of the second cylinder 6. The knock adjustment means 10 adjusts occurrence of knocking in the second cylinder 6.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine provided with a first cylinder and a second cylinder arranged side by side.

  Conventionally, in order to improve thermal efficiency and improve fuel efficiency, an internal combustion engine provided with a plurality of two or more cylinders having different compression ratios has been disclosed (see, for example, Patent Document 1). In Patent Document 1, both a low compression ratio first cylinder and a high compression ratio second cylinder in a low load region, a medium load region, and a high load region according to the combination of the rotational speed and the load of the internal combustion engine. The internal combustion engine is operated by properly using a cylinder.

JP, 2015-68238, A

  In Patent Document 1, the first cylinder and the second cylinder are used properly depending on the number of revolutions of the internal combustion engine and the three load regions. Therefore, for example, while the second cylinder with a high compression ratio is at rest, the air-fuel ratio of the exhaust gas of the internal combustion engine becomes lean. As a result, the purification efficiency of the catalyst attached to the internal combustion engine is reduced.

  An object of the present invention is to provide an internal combustion engine capable of maintaining the purification efficiency of a catalyst while improving the output (torque) while suppressing the occurrence of knocking.

  An internal combustion engine according to the present invention includes an air-fuel ratio detection unit that detects an air-fuel ratio of exhaust gas discharged from a first cylinder, a second cylinder, the first cylinder and the second cylinder, and a combustion chamber of the second cylinder. A first control unit that controls the fuel injection valve of the first cylinder and the fuel injection valve of the second cylinder so as to form a rich region that is richer than the air fuel ratio in the combustion chamber of one cylinder, and knocking of the second cylinder And knock adjusting means for adjusting

  In this internal combustion engine, the air-fuel ratio of the second cylinder becomes richer than the air-fuel ratio of the first cylinder by the control of the first control unit. That is, the fuel concentration of the air-fuel mixture of the second cylinder is higher than the fuel concentration of the air-fuel mixture of the first cylinder. As a result, the air-fuel mixture in the second cylinder is cooled more than the first cylinder due to the vaporization latent heat of the fuel becoming larger than that of the first cylinder.

  Thereby, the occurrence of knocking in the second cylinder is suppressed more than in the first cylinder. Even if the output (torque) generated in the second cylinder is increased by the amount by which knocking is suppressed, knocking becomes difficult to occur, so the knock adjustment means knocks so that the output (torque) of the second cylinder increases. Adjust the

  Further, the knock adjustment means may set the compression ratio of the second cylinder to be higher than the compression ratio of the first cylinder. Thus, the output (torque) of the second cylinder can be increased by setting the compression ratio of the second cylinder higher than the compression ratio of the first cylinder.

  The internal combustion engine may further include an igniter for igniting a mixture of the first cylinder and the second cylinder. The knock adjustment means may increase the output (torque) by advancing the ignition timing of the second cylinder relative to the ignition timing of the first cylinder.

  The first control unit may control the air-fuel ratio of the exhaust gas discharged from the first cylinder and the second cylinder to be the stoichiometric air-fuel ratio. Thereby, the purification efficiency of the catalyst can be maintained.

  The first control unit may control the air-fuel ratio of the second cylinder to be richer than the stoichiometric air-fuel ratio and control the air-fuel ratio of the first cylinder to be leaner than the stoichiometric air-fuel ratio. Thereby, the specific heat ratio of the working fluid in the expansion stroke of the second cylinder can be improved as compared to the first cylinder.

  The igniter may also have a spark plug. The rich region of the second cylinder may be limited to the periphery of the spark plug. The first control unit may control the fuel injection valve of the second cylinder such that the air-fuel ratio of the entire second cylinder becomes the stoichiometric air-fuel ratio.

  According to this configuration, the first control unit can make the air-fuel ratio around the spark plug of the second cylinder richer than that of the first cylinder. In addition, the first control unit can make the air-fuel ratio at a location farther from the spark plug of the second cylinder leaner than that of the first cylinder. That is, the first control unit can control the fuel injection valve of the second cylinder such that the air-fuel mixture in the second cylinder is stratified. As a result, the combustion gas at the second combustion stage of the second cylinder becomes leaner than the first cylinder. As a result, the occurrence of knocking is further suppressed in the second cylinder than in the first cylinder.

  The internal combustion engine includes a first intake passage, a first throttle valve, a first exhaust passage, a second intake passage, a second throttle valve, a second exhaust passage, an exhaust circulation passage, and an exhaust throttle valve. And a second control unit. The first intake passage communicates with the first cylinder. The first throttle valve adjusts the amount of air passing through the first intake passage. The first exhaust passage communicates with the first cylinder, and the exhaust of the first cylinder passes through. The second intake passage communicates with the second cylinder. The second throttle valve regulates the amount of air passing through the second intake passage. The second exhaust passage communicates with the second cylinder, and the exhaust of the second cylinder passes through. The exhaust circulation passage circulates the exhaust of the second cylinder from the second exhaust passage to the first intake passage. An exhaust throttle valve is provided in the second exhaust passage. The exhaust throttle valve regulates the amount of exhaust flowing to the exhaust circulation passage. The second control unit controls the first throttle valve, the second throttle valve, and the exhaust throttle valve so that the amount of exhaust gas circulating in the first intake passage becomes a predetermined ratio with respect to the amount of air passing through the first intake passage. You may adjust the

  In this internal combustion engine, the exhaust of the second cylinder can be circulated from the second exhaust passage to the first intake passage. That is, the unburned gas contained in the exhaust of the second cylinder, which is richer than the first cylinder, can be burned again in the first cylinder. As a result, it is possible to reduce unburned fuel and incomplete combustion gas (such as hydrogen and carbon monoxide) generated in the second cylinder. As a result, the fuel efficiency of the internal combustion engine is improved. Further, in the internal combustion engine, the second exhaust passage is in communication with the first intake passage. Thus, the exhaust pressure of the second cylinder is lower than that of the first cylinder. As a result, the exhaust gas returning from the second exhaust passage back to the second cylinder is small, and the occurrence of knocking is suppressed. That is, in the second cylinder, it is easy to set the isovolume of combustion higher by the knock adjustment means than in the first cylinder. Therefore, the output of the second cylinder can be improved (torque can be increased). Further, in this internal combustion engine, the second control unit controls the second throttle valve and the first throttle valve so that the amount of exhaust gas circulating in the first intake passage becomes a predetermined ratio to the amount of air passing through the first intake passage. The throttle valve and exhaust throttle valve are adjusted. The predetermined ratio may be, for example, a ratio at which the first cylinder does not misfire. As a result, the misfire of the first cylinder is prevented, and the exhaust gas of the second cylinder whose specific heat ratio of the working fluid in the expansion stroke is improved is recirculated to the first cylinder, whereby the thermal efficiency of the entire engine is improved. As a result, the fuel efficiency of the internal combustion engine is improved.

  According to the present invention, it is possible to maintain the purification efficiency of the catalyst while improving the output (torque) while suppressing the occurrence of knocking in the internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing of the internal combustion engine of 1st Embodiment of this invention. 1 is a block diagram showing a configuration of a control system of an internal combustion engine of a first embodiment. BRIEF DESCRIPTION OF THE DRAWINGS The top view which shows schematic structure of the internal combustion engine of 1st Embodiment. 6 is a flowchart showing control operation of the first control unit of the first embodiment. The figure which shows the cross section of the internal combustion engine of 2nd Embodiment, and the structure of the control system. 7 is a flowchart showing the control operation of the control means of the second embodiment. The top view which shows schematic structure of the internal combustion engine of 3rd Embodiment. The block diagram which shows the structure of the control system of 3rd Embodiment. The flowchart which shows control operation of 3rd Embodiment.

First Embodiment
Hereinafter, an internal combustion engine 2 according to a first embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the internal combustion engine 2 according to the first embodiment includes a first cylinder 4, a second cylinder 6, an air-fuel ratio detection unit 7, a first control unit 8 (see FIG. 2), and knock adjustment. Means 10 (see FIG. 2). In addition, the internal combustion engine 2 further includes an igniter 40. The igniter 40 has a spark plug 41. The igniter 40 ignites the mixture of the first cylinder 4 and the second cylinder 6 through the spark plug 41. The first control unit 8 is a functional configuration realized by software in an ECU (Engine Control Unit) 9 that electrically controls the internal combustion engine 2.

  The first cylinder 4 has a first piston 18 and a first connecting rod 20. Further, the first cylinder 4 is configured of a cylinder block 12 and a cylinder head 14.

  At least one first cylinder 4 and second cylinder 6 are arranged side by side in the cylinder block 12. In the first embodiment, the internal combustion engine 2 is, for example, an in-line four-cylinder internal combustion engine. As shown in FIG. 3, in the case of an in-line four-cylinder engine, cylinders # 1 to # 4 are arranged in series in the cylinder block 12.

  As shown in FIG. 1, the first piston 18 is slidably accommodated inside the first cylinder 4 in the first cylinder 4. The first piston 18 is connected to the crankshaft 16 via a first connecting rod 20. The first piston 18 constitutes a first combustion chamber 22 in a space surrounded by the cylinder head 14 and the top surface of the first piston 18 in a state where the first piston 18 is elevated to the compression top dead center. As shown in FIG. 3, in the first embodiment, the first cylinder 4 is cylinders # 1 to # 3.

  As shown in FIG. 1, the second cylinder 6 has a second piston 24 and a second connecting rod 26. Further, the second cylinder 6 is configured of a cylinder block 12 and a cylinder head 14.

  The second piston 24 is slidably housed inside the second cylinder 6 in the second cylinder 6. The second piston 24 is connected to the crankshaft 16 via a second connecting rod 26. The second piston 24 constitutes a second combustion chamber 28 in a space surrounded by the cylinder head 14 and the top surface of the second piston 24 in a state where the second piston 24 is elevated to the compression top dead center. In the first embodiment, the second cylinder 6 is the cylinder # 4.

  As shown in FIG. 1, a crankshaft 16 is rotatably held by the cylinder block 12. An oil pan 32 is provided on the mating surface 30 of the cylinder block 12 via a liquid gasket (not shown). A water jacket 37 is provided around the cylinders # 1 to # 4 of the cylinder block 12 to cool the cylinders # 1 to # 4. A crank angle sensor 42 is provided on the side surface of the cylinder block 12 and detects the rotation speed of the internal combustion engine 2 by detecting the rotation of the crankshaft 16. As shown in FIG. 2, the crank angle sensor 42 is electrically connected to the ECU 9.

  As shown in FIG. 1, a cylinder head 14 is provided on a mating surface 36 opposite to the mating surface 30 of the cylinder block 12 via a cylinder head gasket (not shown). A pent roof type recess 39 is provided at a position corresponding to cylinder # 1 to cylinder # 4 of the cylinder head 14. An igniter 40 is provided at the top of the pent roof type recess 39.

  The igniter 40 has a spark plug 41 and a spark coil 45. The igniter 40 is provided in each of the first cylinder 4 and the second cylinder 6, and ignites the mixture of the first cylinder 4 and the second cylinder 6 via the spark plug 41. The spark plug 41 is provided with a tip protruding into the first combustion chamber 22 and the second combustion chamber 28. The spark plug 41 generates a spark when a high voltage is applied by the ignition coil 45 to ignite the mixture of the first cylinder 4 and the second cylinder 6. As shown in FIG. 2, the igniter 40 is electrically connected to the ECU 9.

  As shown in FIG. 1, an intake port 44 and an exhaust port 46 are provided on both sides of the igniter 40. An intake valve 48 is provided at the intake port 44, and is driven to open and close at timing of intake from cylinder # 1 to cylinder # 4. Similarly, the exhaust port 46 is provided with an exhaust valve 50, which is driven to open and close at timing of exhaust from the cylinder # 1 to the cylinder # 4. Although not shown, in the first embodiment, two intake ports 44, two exhaust ports 46, two intake valves 48, and two exhaust valves 50 are provided for each of the cylinders # 1 to # 4. That is, in the first embodiment, the internal combustion engine 2 is a four-valve type.

  The intake valve 48 and the exhaust valve 50 are driven by a valve drive device 51. In the first embodiment, the valve drive device 51 has a pair of camshafts 53 that rotate in synchronization with the crankshaft 16.

  Below the intake port 44, a fuel injection valve 52 for directly injecting fuel into the cylinders # 1 to # 4 is provided. The fuel injection valve 52 is provided in each of the first cylinder 4 and the second cylinder 6 and injects fuel into the first cylinder 4 and the second cylinder 6. The fuel injection valve 52 is electrically connected to the ECU 9 as shown in FIG.

  The intake port 44 is connected to the intake manifold 64 to form an intake passage 66. A throttle valve 68 (an alternate long and short dash line in FIG. 1) is connected to the intake passage 66 to adjust the amount of air passing through the intake passage 66. An intake duct 70 is connected to the throttle valve 68. An air cleaner 72 is connected to the intake duct 70, and air in the atmosphere is supplied from the cylinder # 1 to the cylinder # 4 via the air cleaner 72. The throttle valve 68 is provided with a throttle opening degree sensor 74 for detecting the throttle opening degree. As shown in FIG. 2, the throttle valve 68 and the throttle opening degree sensor 74 are electrically connected to the ECU 9. An air flow sensor 75 is provided in the intake duct 70. The air flow sensor 75 measures the amount of air passing through the intake duct 70. The air flow sensor 75 is electrically connected to the ECU 9 as shown in FIG.

  The exhaust port 46 is connected to the exhaust manifold 76 and constitutes an exhaust passage 77. Connected to the exhaust passage 77 is a three-way catalyst 78 for purifying the exhaust gas discharged from the internal combustion engine 2. An air-fuel ratio detection unit 7 is provided in the exhaust passage 77 on the upstream side of the three-way catalyst 78.

  The air-fuel ratio detection unit 7 detects an air-fuel ratio (exhaust air-fuel ratio) of the exhaust gas discharged from the first cylinder 4 and the second cylinder 6. In the first embodiment, the air-fuel ratio detection unit 7 is an air-fuel ratio sensor that detects the air-fuel ratio of the exhaust gas and linearly outputs the detected air-fuel ratio. The air-fuel ratio detection unit 7 may be an O 2 sensor that detects the oxygen concentration of the exhaust gas and outputs whether the air-fuel ratio of the exhaust gas is richer or leaner than the theoretical air-fuel ratio. As shown in FIG. 2, the air-fuel ratio detection unit 7 is electrically connected to the ECU 9.

  The ECU 9 has a first control unit 8 and a driving state detection unit 84. Although not illustrated, the ECU 9 is configured by a microcomputer including a CPU (Central Processing Unit), a memory, an input / output buffer and the like. The ECU 9 controls various devices so as to achieve a desired operating state of the internal combustion engine 2 based on the signals from the respective sensors and devices and the map and program stored in the memory. The various controls are not limited to software processing, and may be processed by dedicated hardware (electronic circuits).

  The first control unit 8 sets the fuel injection valve 52 of the first cylinder 4 and the fuel injection valve of the second cylinder 6 so as to form a rich region in which the air fuel ratio of the second cylinder 6 becomes richer than the first cylinder 4. Control 52 Further, the first control unit 8 controls the fuel injection valve 52 of the first cylinder 4 and the fuel injection valve 52 of the second cylinder 6 so that the air-fuel ratio of the exhaust detected by the air-fuel ratio detection unit 7 becomes a predetermined value. Control. In the first embodiment, the predetermined value is, for example, the stoichiometric air fuel ratio. Therefore, the first control unit 8 makes the first cylinder 4 lean as much as the second cylinder 6 becomes rich so that the stoichiometric air-fuel ratio becomes a total. Further, the operating state detection unit 84 detects the rotational speed of the internal combustion engine 2 detected by the crank angle sensor 42, the throttle opening degree detected by the throttle opening degree sensor 74, and the air amount detected by the air flow sensor 75. Detect the driving condition.

  The first control unit 8 calculates the amount of air taken into the second cylinder 6 from the output (torque) required of the internal combustion engine 2 and the rotational speed of the internal combustion engine 2 detected by the operating state detection unit 84. . The first control unit 8 sets, for example, a target air-fuel ratio at which the air-fuel ratio of the second cylinder 6 is richer than the stoichiometric air-fuel ratio with respect to the calculated air amount. The first control unit 8 determines the fuel injection amount to be injected by the fuel injection valve 52 of the second cylinder 6 based on the target air-fuel ratio. After determining the fuel injection amount, the first control unit 8 instructs the fuel injection valve 52 on the fuel injection amount and the injection timing. The fuel injection valve 52 injects fuel to the second cylinder 6 based on the fuel injection amount and the injection timing instructed from the first control unit 8. The fuel injection timing in the first embodiment is the intake stroke of the second cylinder 6 except when performing a stratified stoichiometric operation described later.

  Further, the first control unit 8 may make the air-fuel ratio of part of the combustion chamber of the second cylinder 6 rich. In this case, the first control unit 8 makes the air-fuel ratio of the periphery 43 of the spark plug 41 of the second cylinder 6 rich. That is, the first control unit 8 sets, for example, the target air-fuel ratio of the second cylinder 6 to the theoretical air-fuel ratio with respect to the calculated air amount. The first control unit 8 determines the fuel injection amount to be injected by the fuel injection valve 52 of the second cylinder 6 based on the set target air-fuel ratio. After determining the fuel injection amount, the first control unit 8 instructs the fuel injection valve 52 on the fuel injection amount and the injection timing. In this case, the first control unit 8 determines the fuel injection timing as the compression stroke of the second cylinder 6. As described above, the fuel is injected in the compression stroke of the second cylinder 6 to make the air-fuel ratio of the periphery 43 of the spark plug 41 of the second cylinder 6 rich, while the portions other than the periphery 43 of the spark plug 41 Layered combustion is possible that is lean. Further, since the air-fuel ratio of all the second cylinders 6 can be set to the stoichiometric air-fuel ratio (stoichiometric), it is not necessary to set the first cylinders 4 lean. Such a combustion mode is called stratified stoichiometric combustion, and operating the internal combustion engine 2 by stratified stoichiometric combustion is called stratified stoichiometric operation.

  The specific heat ratio of the burnt gas after combustion of the air-fuel mixture is improved by the air-fuel mixture in which the air-fuel ratio is richer than the stoichiometric air-fuel ratio than the air-fuel ratio in which the air-fuel ratio is the stoichiometric air-fuel ratio. Similarly, in the case of an air-fuel mixture in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, the specific heat ratio of the burned gas is improved. As a result, the specific heat ratio of the working fluid in the expansion stroke of the internal combustion engine is improved. That is, in the combustion chamber of the second cylinder 6, the internal combustion engine 2 forms a region richer than the stoichiometric air fuel ratio, and if the first cylinder 4 is leaner than the stoichiometric air fuel ratio, the specific heat ratio improves. Thereby, the specific heat ratio of the working fluid in the expansion stroke of the internal combustion engine 2 is improved.

  Knock adjustment means 10 adjusts the occurrence of knocking. In the first embodiment, the compression ratio of the second cylinder 6 is set to be higher than the compression ratio of the first cylinder 4 by controlling the variable compression ratio mechanism 17 provided on the crankshaft 16 by the knock adjustment means 10. Do. That is, the stroke length of the crankshaft 16 of the second cylinder 6 is controlled to be longer than that of the first cylinder 4 by the knock adjustment means 10, and the position of the surface of the second piston 24 is varied. The compression ratio of 6 is set to be higher than that of the first cylinder 4. The variable compression ratio mechanism 17 may be provided to the second piston 24 or the second connecting rod 26 as long as it is a mechanism that changes the position of the top surface of the second piston 24. The variable compression ratio mechanism 17 may be any other mechanism as long as it can change the position of the top surface of the second piston 24. As described above, in the first embodiment, the compression ratio of the second cylinder 6 is adjusted to be higher than the compression ratio of the first cylinder 4 by the mechanical structure. As a result, the theoretical thermal efficiency of the second cylinder 6 can be set higher than that of the first cylinder 4.

  Although the generated output (torque) increases as the compression ratio increases, knocking is more likely to occur. However, the second cylinder 6 is richer in air-fuel ratio than the first cylinder 4. As a result, the latent heat of vaporization of the second cylinder 6 becomes larger than that of the first cylinder 4 and the air-fuel mixture is cooled. As a result, the occurrence of knocking is suppressed. Further, when the second cylinder 6 is in the stratified stoichiometric combustion, the end gas region which is the starting point of the occurrence of knocking becomes lean, so the occurrence of knocking is suppressed. Therefore, the knock adjustment means 10 can set the compression ratio of the second cylinder 6 higher than that of the first cylinder 4. Thus, the knock adjustment means 10 adjusts the occurrence of knocking so that the output (torque) of the second cylinder 6 is increased by setting the compression ratio of the second cylinder 6.

  Next, control performed by the first control unit 8 in the first embodiment will be described using the flowchart of FIG. 4.

  In step S1, the first control unit 8 targets the internal combustion engine 2 from the output (torque) required of the internal combustion engine 2 and the rotational speed of the internal combustion engine 2 detected by the operating state detection unit 84. The intake air amount T_air is calculated. Here, the target intake air amount T_air corresponds to the amount of air passing through the intake passage 66. After calculating the target intake air amount T_air, the first control unit 8 proceeds the process to step S2.

  In step S2, the first control unit 8 sets a target air-fuel ratio AF_T2 of the second cylinder 6. The first control unit 8 makes the target air-fuel ratio AF_T2 of the second cylinder 6 richer than the stoichiometric air-fuel ratio AF_L, for example, based on the operating condition of the internal combustion engine 2 detected by the operating condition detecting unit 84. , To set. The setting of the target air-fuel ratio AF_T2 of the second cylinder 6 may refer to the map of the target air-fuel ratio AF_T2 stored in the memory of the ECU 9 according to the operating state. After setting the target air-fuel ratio AF_T2 of the second cylinder 6, the first control unit 8 advances the process to step S3.

  In step S3, the first control unit 8 sets a target air-fuel ratio AF_T1 of the first cylinder 4. The first control unit 8 sets the target air-fuel ratio AF_T1 of each cylinder of the first cylinder 4 so as to bring the enrichment of the second cylinder 6 to the stoichiometric air-fuel ratio as a whole internal combustion engine in all the cylinders of the first cylinder 4. Set to the lean side.

  After setting the target air-fuel ratio AF_T1 of the first cylinder 4, the first control unit 8 proceeds the process to step S4.

  In step S4, the first control unit 8 calculates the target fuel injection amount F_T2 and injection timing Ft_T2 of the second cylinder 6 from the target intake air amount T_air and the target air-fuel ratio AF_T2. Similarly, the first control unit 8 calculates a target fuel injection amount F_T1 and an injection timing Ft_T1 of the first cylinder 4 from the target intake air amount T_air and the target air-fuel ratio AF_T1. After calculating the target fuel injection amount F_T1 and the target fuel injection amount F_T2, the first control unit 8 calculates the target fuel injection amount and fuel for the fuel injection valve 52 of each cylinder of the first cylinder 4 and the second cylinder 6 It converts into the pulse signal which shows the opening / closing timing of the injection valve 52, and transmits. The fuel injection valve 52 injects fuel in accordance with the designated pulse signal. After transmitting the pulse signal, the first control unit 8 advances the process to step S5.

  In step S5, the first control unit 8 acquires the exhaust air-fuel ratio value AF_e from the air-fuel ratio detection unit 7. The exhaust air-fuel ratio value AF_e is a value indicating the air-fuel ratio from the gas component in the exhaust gas. After obtaining the exhaust air-fuel ratio value AF_e, the first control unit 8 proceeds the process to step S6.

  In step S6, the first control unit 8 determines whether the exhaust air-fuel ratio value AF_e is within a predetermined range with respect to the predetermined value AF_D. The target air-fuel ratio AF_T1 for the first cylinder 4 and the target air-fuel ratio AF_T2 for the second cylinder 6 if the exhaust air-fuel ratio can be detected for each of the first cylinder 4 and the second cylinder 6 In the case where the exhaust air-fuel ratio of the entire internal combustion engine is to be detected, it is determined whether or not it is within a predetermined range with respect to the theoretical air-fuel ratio, and the actually burned fuel is targeted It is determined how much the fuel injection amount F_T1 and F_T2 are deviated. The first control unit 8 determines whether or not the predetermined value AF_D is within the predetermined range, and proceeds to step S7 if it is not within the predetermined range. On the other hand, when the exhaust air-fuel ratio value AF_e is within the predetermined range with respect to the predetermined value AF_D, the first control unit 8 returns the process to step S1. In the case of stratified stoichiometric combustion, it is determined whether the first cylinder 4 and the second cylinder 6 are all within a predetermined range with respect to the theoretical air fuel ratio.

  In step S7, the first control unit 8 sets the target fuel injection amount F_T1 of the first cylinder 4 and the target fuel injection amount F_T2 of the second cylinder 6 according to the difference between the exhaust air fuel ratio value AF_e and the predetermined value AF_D. Correct the For example, when the exhaust air-fuel ratio value AF_e is richer than the predetermined value AF_D, the first control unit 8 decreases the fuel injection amount of the target fuel injection amount F_T1 of the first cylinder 4. For example, when the exhaust air-fuel ratio value AF_e is leaner than the predetermined value AF_D, the fuel injection amount of the target fuel injection amount F_T2 of the second cylinder 6 is increased. As described above, by increasing or decreasing the target fuel injection amount F_T1 of the first cylinder 4 and the target fuel injection amount F_T2 of the second cylinder 6, the air-fuel ratio of the second cylinder 6 can be set richer. As a result, the specific heat ratio of the working fluid in the expansion stroke of the second cylinder 6 can be set higher. After correcting the target fuel injection amount F_T1 of the first cylinder 4 and the target fuel injection amount F_T2 of the second cylinder 6, the first control unit 8 returns the process to step S1.

Second Embodiment
Next, an internal combustion engine 202 according to a second embodiment of the present invention will be described with reference to the drawings. In the following description, the same components as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and the description thereof is omitted.

  An internal combustion engine 202 according to the second embodiment includes a first cylinder 4, a second cylinder 206, a first control unit 8, knock adjustment means 210, and an ignition device 40. The igniter 40 has a spark plug 41. The igniter 40 ignites the mixture of the first cylinder 4 and the second cylinder 206 through the spark plug 41. The first control unit 8 and the knock adjustment unit 210 are functional configurations realized by software in the ECU 209. The first control unit 8 controls the fuel injection valve 52 of the first cylinder 4 and the second cylinder 206 so as to form a rich region in the combustion chamber of the second cylinder 206 that is richer than the air fuel ratio of the first cylinder 4. The fuel injection valve 52 is controlled. In addition, the first control unit 8 controls the fuel injection valve 52 of the first cylinder 4 and the fuel injection valve 52 of the second cylinder 206 so that the air-fuel ratio of the exhaust detected by the air-fuel ratio detection unit 7 becomes a predetermined value. Control. Therefore, in the second embodiment, the second piston 224 of the second cylinder 206 has, for example, the same shape as the first piston 18 of the first embodiment. The other mechanical structure of the internal combustion engine is the same as that of the first embodiment, and thus the description thereof is omitted.

  The knock adjustment means 210 advances the ignition timing of the ignition device 40 of the second cylinder 206 by controlling the ignition device 40. If the igniter 40 is ignited by the optimal ignition timing, the isovolume of combustion will be greater than the other ignition timings. As a result, the second cylinder 206 can obtain the maximum output (maximum torque) in the operating state detected by the operating state detection unit 84. Here, advancing the ignition timing means setting the optimum ignition timing or approaching the optimum ignition timing.

  However, in order for the igniter 40 to ignite at the optimum ignition timing, the occurrence of knocking must be suppressed. In the second embodiment, as in the first embodiment, the first control unit 8 causes the second cylinder 206 to form a rich region in the combustion chamber of the second cylinder 206 that is richer than the first cylinder 4. Control the fuel injection valve 52 of As a result, the second cylinder 206 is cooled more than the first cylinder 4 due to the vaporization latent heat becoming larger than the first cylinder 4. As a result, the occurrence of knocking is suppressed. For this reason, the knock adjustment means 210 can advance the ignition timing of the second cylinder 206 to make the optimal ignition timing closer. Thereby, the equal volume of the combustion of the second cylinder 206 can be set high. Further, the output (torque) of the second cylinder 206 can be increased.

  Next, control performed by the knock adjustment means 210 in the second embodiment will be described using the flowchart of FIG.

  In step S201, knock adjustment means 210 acquires target air-fuel ratio AF_T2 of second cylinder 206. Knock adjustment means 210 proceeds with the process to step S202 after acquiring target air-fuel ratio AF_T2.

  In step S 202, knock adjustment means 210 determines whether target air-fuel ratio AF_T 2 of second cylinder 206 is richer than target air-fuel ratio AF_T 1 of first cylinder 4. In the second embodiment, when the target air-fuel ratio AF_T2 is richer than the target air-fuel ratio AF_T1, the process proceeds to step S203. On the other hand, if the target air-fuel ratio AF_T2 is the same as the target air-fuel ratio AF_T1 or is lean, the process proceeds to step S204.

  In step S204, knock adjustment means 210 determines whether or not second cylinder 206 is in stratified stoichiometric operation. If the second cylinder 206 is in stratified stoichiometric operation, the process proceeds to step S203. If it is not the stratified stoichiometric operation, knock adjustment means 210 returns the processing to step S201.

  In step S203, knock adjustment means 210 refers to rich operation ignition timing map R. The rich operation ignition timing map R is a map referred to in the operating condition (rich operating condition) for forming a rich region which is richer than the first cylinder 4 in the combustion chamber of the second cylinder 206. The rich operation ignition timing map R is a map in which the ignition timing is advanced more than the normal ignition timing map L which is referred to when the rich operation condition is not set. That is, the ignition timing map R is a map in which there are many regions in which the ignition timing is optimal than the ignition timing map L. The knock adjustment means 210 sets the ignition timing of the first cylinder 4 with reference to the ignition timing map L. After referring to the ignition timing map R, the knock adjustment means 210 proceeds to step S205.

  In step S205, knock adjustment means 210 advances the ignition timing of ignition device 40 in accordance with the ignition timing of ignition timing map R. After advancing the ignition timing, knock adjustment means 210 returns the process to step S201.

Third Embodiment
Next, an internal combustion engine 302 according to a third embodiment of the present invention will be described with reference to the drawings.

  In the third embodiment, only points different from the second embodiment will be described. The same reference numerals as in the first embodiment and the second embodiment denote the same parts as in the first embodiment and the second embodiment, and a description thereof will be omitted.

  As shown in FIG. 7, the internal combustion engine 302 in the third embodiment includes a first cylinder 4, a second cylinder 206, a first control unit 8 (see FIG. 8), and a knock adjustment unit 210 (see FIG. 8). And a second control unit 383 (see FIG. 8). The internal combustion engine 302 also includes a first intake passage 366, a first throttle valve 368, a first exhaust passage 377, a second intake passage 369, a second throttle valve 375, a second exhaust passage 379, and exhaust. Throttle valve 380 and exhaust circulation passage 389 are further provided.

  The first intake passage 366 has a first intake manifold 364 and an intake port 44 (see FIG. 5) of the first cylinder 4. The first intake manifold 364 is connected to the intake port 44 of the first cylinder 4. The intake port 44 communicates with the first cylinder 4. Further, a first throttle valve 368 is connected to the first intake manifold 364. The first throttle valve 368 regulates the amount of air passing through the first intake passage 366. The first throttle valve 368 is provided with a first throttle opening sensor 374 for detecting the throttle opening. As shown in FIG. 8, the first throttle valve 368 and the first throttle opening sensor 374 are electrically connected to the ECU 309. The first throttle valve 368 is connected to the intake duct 370.

  The first exhaust passage 377 has an exhaust manifold 376 and an exhaust port 46 (see FIG. 5) of the first cylinder 4. The exhaust manifold 376 is connected to the exhaust port 46 of the first cylinder 4. The exhaust port 46 communicates with the first cylinder 4.

  The second intake passage 369 has a second intake manifold 371 and an intake port 44 of the second cylinder 206. The second intake manifold 371 is connected to the intake port 44 of the second cylinder 206. The intake port 44 communicates with the second cylinder 206. Further, a second throttle valve 375 is connected to the second intake manifold 371. The second throttle valve 375 adjusts the amount of air passing through the second intake passage 369. The second throttle valve 375 is provided with a second throttle opening sensor 378 that detects the throttle opening. As shown in FIG. 8, the second throttle valve 375 and the second throttle opening degree sensor 378 are electrically connected to the ECU 309. The second throttle valve 375 is connected to the intake duct 370.

  The second exhaust passage 379 has an exhaust manifold 376 and an exhaust port 46 of the second cylinder 206. The exhaust manifold 376 is connected to the exhaust port 46 of the second cylinder 206. The exhaust port 46 communicates with the second cylinder 206.

  The exhaust circulation passage 389 is connected to the first intake passage 366 at one end. The other end of the exhaust circulation passage 389 is connected to the second exhaust passage 379 at a connection 381. The exhaust circulation passage 389 communicates with the first intake passage 366 and the second exhaust passage 379, and circulates the exhaust of the second cylinder 206 into the first intake passage 366.

  An exhaust throttle valve 380 is provided downstream of the connecting portion 381 of the second exhaust passage 379 and upstream of the exhaust collecting portion 385. The exhaust throttle valve 380 adjusts the amount of exhaust flowing to the exhaust circulation passage 389 by opening and closing. The exhaust throttle valve 380 is provided with an exhaust throttle opening degree sensor 386 for detecting the throttle opening degree. As shown in FIG. 8, the exhaust throttle valve 380 and the exhaust throttle opening degree sensor 386 are electrically connected to the ECU 309.

  As shown in FIG. 8, the ECU 309 includes a first control unit 8, an operating state detection unit 84, a knock adjustment unit 210, and a second control unit 383. The first control unit 8, the driving state detection unit 84, the knock adjustment unit 210, and the second control unit 383 are functional configurations realized by software in the ECU 309.

  The second control unit 383 controls the first throttle valve 368 and the second throttle valve 375 so that the amount of exhaust gas circulating in the first intake passage 366 becomes a predetermined ratio with respect to the amount of air passing through the first intake passage 366. And adjust the exhaust throttle valve 380. Here, the predetermined ratio may be, for example, a ratio at which the first cylinder 4 does not misfire. According to the findings of the inventors, the rate at which the first cylinder 4 does not misfire is within 65% of the amount of air passing through the first intake passage 366. Thereby, the misfire of the first cylinder 4 can be prevented, and the thermal efficiency of the internal combustion engine 302 can be improved.

  The knock adjustment means 210 is a means for advancing the ignition timing of the second cylinder 206 as in the second embodiment. Knock adjustment means 210 is included in the ECU 309.

  Next, control performed by the second control unit 383 in the third embodiment will be described with reference to the flowchart of FIG.

  In step S301, the second control unit 383 acquires the target intake air amount T_air calculated by the first control unit 8. Here, the target intake air amount T_air corresponds to the amount of air passing through the first intake passage 366 or the second intake passage 369. After acquiring the target intake air amount T_air, the second control unit 383 advances the process to step S302.

  In step S302, the second control unit 383 calculates a target exhaust circulation amount EGR_T. The target exhaust circulation amount EGR_T corresponds to the amount of the exhaust that circulates in the first intake passage 366 among the exhaust of the second cylinder 206. Here, the second control unit 383 calculates the target exhaust circulation amount EGR_T such that the target exhaust circulation amount EGR_T becomes a predetermined ratio E_d with respect to the target intake air amount T_air. That is, the predetermined ratio E_d is a value indicating the ratio of the target exhaust circulation amount EGR_T to the target intake air amount T_air. The predetermined ratio E_d is preset to be a ratio at which the first cylinder 4 does not misfire. The second control unit 383 may refer to the map E indicating the target exhaust circulation amount EGR_T or the predetermined ratio E_d according to the operating state of the internal combustion engine 302. After calculating the target exhaust circulation amount EGR_T, the second control unit 383 advances the processing to step S303.

  In step S303, the second control unit 383 sets the target opening degree T1_t of the first throttle valve 368 from the information of the target intake air amount T_air. After transmitting the target opening degree T1_t to the first throttle valve 368, the second control unit 383 advances the process to step S304.

  In step S304, the second control unit 383 sets the target opening degree T2_t of the second throttle valve 375 from the target intake air amount T_air and the information of the target exhaust circulation amount EGR_T. After transmitting the target opening degree T2_t to the second throttle valve 375, the second control unit 383 advances the process to step S305.

  In step S305, the second control unit 383 sets the target opening degree ET_t of the exhaust throttle valve 380 from the information of the target exhaust circulation amount EGR_T. The target opening degree ET_t decreases as the target exhaust circulation amount EGR_T increases. That is, when the exhaust throttle valve 380 is closed, the exhaust gas circulates to the first intake passage 366 through the exhaust circulation passage 389. In addition, when the exhaust throttle valve 380 is completely closed by the second control unit 383, the first control unit 8 controls the first cylinder so that the air-fuel ratio AF_e of the exhaust of the first exhaust passage 377 becomes the predetermined value AF_D. The target air-fuel ratio AF_T1 of 4 and the target air-fuel ratio AF_T2 of the second cylinder 206 are controlled. That is, when the exhaust throttle valve 380 is completely closed, all the exhaust gas of the second cylinder 206 circulates to the first cylinder 4. Thus, the unburned gas contained in the exhaust gas of the second cylinder 206 can be burned again by the first cylinder 4. After transmitting the target opening degree ET_t to the exhaust throttle valve 380, the second control unit 383 returns the process to step S301.

  Note that the amount of air in the first cylinder 4 is less than that in the second cylinder 206 because the exhaust gas of the second cylinder 206 circulates. Therefore, the target opening degree T1_t of the first throttle valve 368 is larger than the target opening degree T2_t of the second throttle valve 375 in order to compensate for the insufficient air amount. As a result, the second cylinder 206 has a pump loss larger than that of the first cylinder 4. As a result, an output (torque) difference occurs between the first cylinder 4 and the second cylinder 206. On the other hand, the air fuel ratio of the second cylinder 206 is made richer than that of the first cylinder 4 by the first control unit 8, and the ignition timing of the second cylinder 206 is advanced by the knock adjustment means 210 to obtain this output (torque). It can compensate for the difference. Further, by setting the compression ratio of the second cylinder 206 higher than the compression ratio of the first cylinder 4 as in the internal combustion engine according to the first embodiment, this output (torque) difference can be further compensated.

  If the first cylinder 4 is made richer than the theoretical air fuel ratio, and the second cylinder 206 is made lean, the overall air fuel ratio detected by the air fuel ratio detection unit 7 downstream of the exhaust collecting portion becomes the theoretical air fuel ratio, Since the unburned fuel and incomplete combustion gas (such as hydrogen and carbon monoxide) generated in the second cylinder 206 can be re-burned in the first cylinder 4, the thermal efficiency is improved. As described above, according to the present invention, the thermal efficiency can be enhanced while maintaining the purification efficiency of the catalyst of the internal combustion engine.

Other Embodiments
As mentioned above, although three embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention. In particular, the embodiments and modifications described in the present specification can be arbitrarily combined as needed.

  (A) In the first embodiment, the knock adjusting means 10 is provided with the variable compression ratio mechanism 17 to set the compression ratio of the second cylinder 6 higher than that of the first cylinder 4. However, the variable compression ratio mechanism 17 is provided. Instead, the position of the top surface of the second piston 24 of the second cylinder 6 may be set higher than the position of the top surface of the first piston 18 of the first cylinder 4 at the compression top dead center. As a result, the compression ratio of the second cylinder 6 becomes higher than that of the first cylinder 4.

  (B) In the first embodiment, the spark-ignition internal combustion engine has been described, but the present invention is not limited to this. For example, the present invention may be used for a homogeneous charge compression ignition internal combustion engine that is burned without using the igniter 40. Also in the case where the knock adjustment means 10 of the third embodiment and the first embodiment are combined, the present invention may be applied to a premixed compression self-ignition internal combustion engine.

  (C) In the first to third embodiments, a serial internal combustion engine has been described as an example, but the present invention is not limited to this. For example, the present invention may be applied to a horizontally opposed internal combustion engine or a V-type internal combustion engine.

  (D) In the first to third embodiments, one second cylinder 206 is provided, but a plurality of second cylinders 206 may be provided. In this case, in the third embodiment, since the unburned gas contained in the exhaust of the second cylinder 206 is burned again by the first cylinder 4, the number of second cylinders 206 is made smaller than the number of first cylinders 4. Is preferred.

  (E) In the first embodiment and the second embodiment, an exhaust circulation passage may be provided, which allows the exhaust passage 77 and the intake passage 66 to communicate with each other. In this case, since the unburned fuel and incomplete combustion gas (such as hydrogen and carbon monoxide) contained in the exhaust gas of the second cylinder 6, 206 are burned again by the first cylinder 4, the thermal efficiency can be further improved. it can.

2, 202, 302: Internal combustion engine 4: First cylinder 6, 206: Second cylinder 7: Air-fuel ratio detection unit 8: First control unit 10, 210: Knock adjustment means 40: Ignition device 41: Ignition plug 43: Ignition Plug 52: fuel injection valve 66: intake passage 68: throttle valve 77: exhaust passage 366: first intake passage 368: first throttle valve 369: second intake passage 375: second throttle valve 377: first exhaust passage 379: second exhaust passage 380: exhaust throttle valve 383: second control unit 389: exhaust circulation passage
AF_e: Exhaust air-fuel ratio (exhaust air-fuel ratio)
AF_D: predetermined value
E_d: predetermined ratio

Claims (7)

With the first cylinder,
The second cylinder,
An air-fuel ratio detection unit that detects an air-fuel ratio of the exhaust gas discharged from the first cylinder and the second cylinder;
The fuel injection valve of the first cylinder and the fuel injection valve of the second cylinder are controlled to form a rich region richer than the air fuel ratio in the combustion chamber of the first cylinder in the combustion chamber of the second cylinder A first control unit to
Knock adjustment means for adjusting the knocking of the second cylinder;
An internal combustion engine comprising:   The internal combustion engine according to claim 1, wherein the knock adjustment means sets a compression ratio of the second cylinder higher than a compression ratio of the first cylinder. The igniter further includes an igniter for igniting a mixture of the first cylinder and the second cylinder.
The internal combustion engine according to claim 1 or 2, wherein the knock adjustment means advances the ignition timing of the igniter of the second cylinder more than the ignition timing of the first cylinder. The first control unit is
The internal combustion engine according to any one of claims 1 to 3, wherein the air-fuel ratio of the exhaust gas discharged from the first cylinder and the second cylinder is controlled to be the stoichiometric air-fuel ratio. The first control unit is
The internal combustion engine according to any one of claims 1 to 4, wherein the air-fuel ratio of the second cylinder is made richer than the stoichiometric air-fuel ratio, and the air-fuel ratio of the first cylinder is controlled to be leaner than the stoichiometric air-fuel ratio. organ. The igniter comprises a spark plug,
The rich region of the second cylinder is around the spark plug,
6. The fuel injection valve according to claim 3, wherein the first control unit controls the fuel injection valve of the second cylinder such that the air-fuel ratio of the entire second cylinder becomes the stoichiometric air-fuel ratio. Internal combustion engine. A first intake passage communicating with the first cylinder;
A first throttle valve for adjusting an amount of air passing through the first intake passage;
A first exhaust passage in communication with the first cylinder through which the exhaust of the first cylinder passes;
A second intake passage communicating with the second cylinder;
A second throttle valve that adjusts an amount of air passing through the second intake passage;
A second exhaust passage in communication with the second cylinder through which the exhaust of the second cylinder passes;
An exhaust circulation passage that circulates the exhaust of the second cylinder from the second exhaust passage to the first intake passage;
An exhaust throttle valve provided in the second exhaust passage for adjusting the amount of exhaust flowing to the exhaust circulation passage;
The first throttle valve, the second throttle valve, and the exhaust throttle valve are adjusted so that the amount of exhaust gas circulating in the first intake passage becomes a predetermined ratio with respect to the amount of air passing through the first intake passage. The internal combustion engine according to any one of claims 1 to 6, further comprising: a second control unit.