JP2013249789A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine suppressing pulsation of gas including blow-by gas.SOLUTION: An internal combustion engine includes: a crankcase that supports a crankshaft; a cylinder block; a compression ratio variable mechanism that is formed so that the cylinder block relatively moves with respect to the crankcse; a blow-by gas recirculation mean that returns blow-by gas flowing out from between a hole part of the cylinder block and a piston to an engine intake path; and a pulsation detection means that detects pulsation of gas including the blow-by gas. When it is determined that the pulsation is generated in the gas including the blow-by gas by the pulsation detection means, a mechanical compression ratio is changed.

Description

  The present invention relates to an internal combustion engine.

  In the combustion chamber of the internal combustion engine, the air-fuel mixture is burned in a compressed state. It is known that the compression ratio when compressing the air-fuel mixture affects the output torque and the fuel consumption. By increasing the compression ratio, the output torque can be increased or the fuel consumption can be reduced. On the other hand, it is known that if the compression ratio is too high, abnormal combustion such as knocking occurs. In the prior art, an internal combustion engine having a variable compression ratio mechanism capable of changing the compression ratio during an operation period is known.

  When the internal combustion engine is operated, it is known that gas in the cylinder leaks from between the hole of the cylinder block and the piston toward the inside of the crankcase. The blow-by gas leaking from the cylinder into the crankcase includes unburned gas remaining without being burned and burned burned gas. It is known that blow-by gas returns blow-by gas that has flowed into the crankcase to the engine intake passage and supplies it to the combustion chamber again in order to degrade the oil that lubricates each part of the engine body.

  Japanese Patent Application Laid-Open No. 2011-149280 discloses an internal combustion engine in which a compression ratio is changed by relatively sliding a cylinder block and a crankcase in the cylinder axial direction. The internal combustion engine includes a device for scavenging blow-by gas including an introduction passage that guides a part of fresh air flowing through the intake passage to the inside of the crankcase and a discharge passage that guides gas existing inside the crankcase to the intake passage. . An apparatus for scavenging blow-by gas is disclosed that supplies fresh air in the engine intake passage to the cylinder head cover, and further supplies fresh air to the inside of the crankcase through the inside of the cylinder head and the inside of the cylinder block. Yes. Further, it is disclosed that the introduction passage communicates with the inside of the crankcase via a gap between the cylinder block and the crankcase. Furthermore, it is disclosed that a seal material is disposed between the crankcase and the cylinder head, and fresh air is supplied to the seal material.

  In Japanese Patent Application Laid-Open No. 2010-024963, when controlling the torque of the internal combustion engine, a margin value (reserve torque) is added in advance to the required torque, and the throttle valve is opened according to the added torque. Setting the degree is disclosed. Further, it is disclosed that the excessive torque due to this setting is canceled by the retard of the ignition timing, and that when the request for an increase in torque occurs suddenly, the ignition timing is advanced.

JP 2011-149280 A JP 2010-024963 A

  The blow-by gas flowing out from between the hole of the cylinder block and the piston can be returned to the engine intake passage by the blow-by gas reduction device. The blow-by gas that has flowed out between the hole of the cylinder block and the piston flows into the crankcase. The gas containing the blow-by gas stored in the crankcase is supplied to the engine intake passage through the PCV valve and the passage connecting the inside of the crankcase and the engine intake passage.

  By the way, in a predetermined operation state of the internal combustion engine, gas including blow-by gas inside the crankcase may pulsate. For example, pressure pulsation occurs depending on the length of the path from which the blow-by gas flows out between the hole of the cylinder block and the piston and reaches the PCV valve, the natural frequency of the gas containing the blow-by gas, and the like. There is a case.

  When the gas containing the blow-by gas pulsates, for example, the flow rate of the blow-by gas introduced into the engine intake passage via the PCV valve varies. For this reason, the amount of intake air flowing into the cylinder becomes unstable. Alternatively, the blow-by gas contains unburned fuel, and an error occurs in the amount of unburned gas contained in the blow-by gas supplied to the combustion chamber. As a result, in the combustion chamber, ignition may not be performed at the optimal ignition timing, and exhaust properties may deteriorate. Or the fuel consumption may increase.

  Moreover, if the gas containing blow-by gas pulsates, the force which presses a piston toward a compression top dead center will vibrate. That is, since the gas pressure inside the crankcase vibrates, the force that pushes the piston upward vibrates. For this reason, vibration is generated in the torque output from the internal combustion engine, and the stability of operation may be deteriorated, or the vibration generated in the internal combustion engine may be increased. Further, since the pressure at which the gas containing the blow-by gas presses the piston fluctuates, the force applied to the gas in the engine intake passage or the gas in the engine exhaust passage is pulsated by the piston. As a result, there is a risk of inducing gas pulsation in the engine intake passage and the engine exhaust passage.

  In particular, in an internal combustion engine equipped with a supercharger, the pressure of the combustion chamber when the piston reaches top dead center is increased, so the pressure of the gas containing blow-by gas is also increased. Since the pulsation is more likely to occur as the air density is higher, the pulsation of the gas containing blow-by gas is also likely to occur. For this reason, in an internal combustion engine provided with a supercharger, it is desirable to suppress pulsation of gas containing blow-by gas.

  An object of this invention is to provide the internal combustion engine which suppresses the pulsation of the gas containing blowby gas.

  An internal combustion engine of the present invention is formed so that a support structure that supports a crankshaft, a cylinder block that includes a hole in which a piston is disposed, and a cylinder block that moves relative to the support structure. Variable compression ratio mechanism capable of changing the pressure, blowby gas returning means for returning blowby gas flowing out between the hole of the cylinder block and the piston to the engine intake passage, and pulsation detecting means for detecting pulsation of gas containing blowby gas With. When it is determined by the pulsation detection means that pulsation has occurred in the gas containing blow-by gas, the mechanical compression ratio is changed.

  In the above invention, the pulsation detecting means detects the magnitude of the pulsation of the pressure of the gas containing blow-by gas, and the magnitude of the pulsation of the pressure of the gas containing blow-by gas is greater than a predetermined determination value. The mechanical compression ratio can be changed.

  In the above invention, when it is determined that the pulsation is generated in the gas containing the blow-by gas, the mechanical compression ratio can be increased and the ignition timing can be retarded.

  In the above-described invention, an impact detection means for detecting an impact due to fluctuations in output is provided, and when it is determined that pulsation is generated in a gas containing blow-by gas, the mechanical compression ratio is changed and the ignition timing is changed. It is configured to perform control, and when changing the mechanical compression ratio and changing the ignition timing, when an impact due to output fluctuation is detected, the speed and ignition timing for changing the next mechanical compression ratio are changed. The speed can be made slower than the speed for changing the current mechanical compression ratio and the speed for changing the ignition timing.

  In the above-described invention, a pulsation preparation region that may cause pulsation of gas containing blow-by gas is set in advance, and when the operating state of the internal combustion engine is within the pulsation preparation region, the ignition timing is retarded. At the same time, the charging efficiency can be increased, and the mechanical compression ratio can be changed after retarding the ignition timing and increasing the charging efficiency.

  In the above invention, the support structure may include a crankcase that houses the crankshaft therein, and the pulsation detecting means may include a pressure sensor that detects a pressure inside the crankcase.

  ADVANTAGE OF THE INVENTION According to this invention, the internal combustion engine which suppresses the pulsation of the pressure of blowby gas can be provided.

1 is a schematic cross-sectional view of an internal combustion engine in an embodiment. In the internal combustion engine of the embodiment, it is a schematic cross-sectional view of a cylinder block and a crankcase portion when the mechanical compression ratio is a high compression ratio. In the internal combustion engine of the embodiment, it is a schematic cross-sectional view of a cylinder block and a crankcase portion when the mechanical compression ratio is a low compression ratio. It is a schematic sectional drawing of the internal combustion engine explaining the blow-by gas reduction apparatus in embodiment. It is a time chart of the 1st operation control in an embodiment. It is a flowchart of the 1st operation control in an embodiment. It is a graph explaining the pressure in a crankcase when the gas containing blowby gas is pulsating. It is a time chart of the 2nd operation control in an embodiment. It is a flowchart of the 2nd operation control in an embodiment. It is a time chart of the 3rd operation control in an embodiment. It is a flowchart of the 3rd operation control in an embodiment. In the 3rd operation control of an embodiment, it is a graph explaining a pulsation field and a pulsation preparation field. FIG. 10 is a flowchart of control for learning a pulsation region in the third operation control of the embodiment. FIG. FIG. 10 is a flowchart of control for learning a pulsation preparation region in the third operation control of the embodiment. FIG.

  An internal combustion engine according to an embodiment will be described with reference to FIGS. In the present embodiment, an internal combustion engine disposed in a vehicle will be described as an example.

  FIG. 1 is a schematic view of an internal combustion engine in the present embodiment. The internal combustion engine in the present embodiment is a spark ignition type. The internal combustion engine includes an engine body 1. The engine body 1 includes a cylinder block 2 and a cylinder head 4. A piston 3 is disposed inside the cylinder block 2. The piston 3 reciprocates inside the cylinder block 2. The combustion chamber 5 is formed for each cylinder. An engine intake passage and an engine exhaust passage are connected to the combustion chamber 5.

  An intake port 7 and an exhaust port 9 are formed in the cylinder head 4. The intake valve 6 is disposed at the end of the intake port 7 and is configured to be able to open and close the engine intake passage communicating with the combustion chamber 5. The exhaust valve 8 is disposed at the end of the exhaust port 9 and is configured to be able to open and close the engine exhaust passage communicating with the combustion chamber 5. A spark plug 10 as an ignition device is fixed to the cylinder head 4. The spark plug 10 is formed to ignite fuel in the combustion chamber 5.

  The internal combustion engine in the present embodiment includes a fuel injection valve 11 for supplying fuel to the combustion chamber 5. The fuel injection valve 11 in the present embodiment is arranged so as to inject fuel into the intake port 7. The fuel injection valve 11 is not limited to this configuration, and may be arranged so that fuel can be supplied to the combustion chamber 5. For example, the fuel injection valve may be arranged to inject fuel directly into the combustion chamber.

  The fuel injection valve 11 is connected to the fuel tank 28 via an electronically controlled fuel pump 29 with variable discharge amount. The fuel stored in the fuel tank 28 is supplied to the fuel injection valve 11 by the fuel pump 29.

  The intake port 7 of each cylinder is connected to a surge tank 14 via a corresponding intake branch pipe 13. The surge tank 14 is connected to an air cleaner (not shown) through the intake duct 15. An air flow meter 16 that detects the amount of intake air is disposed inside the intake duct 15. A throttle valve 18 driven by a step motor 17 is disposed inside the intake duct 15. On the other hand, the exhaust port 9 of each cylinder is connected to a corresponding exhaust branch pipe 19. The exhaust branch pipe 19 is connected to the exhaust treatment device 21. The exhaust treatment device 21 in the present embodiment includes a three-way catalyst 20. The exhaust treatment device 21 is connected to the exhaust pipe 22.

  The internal combustion engine in the present embodiment includes an electronic control unit 31. The electronic control unit 31 in the present embodiment includes a digital computer. The electronic control unit 31 includes a RAM (random access memory) 33, a ROM (read only memory) 34, a CPU (microprocessor) 35, an input port 36 and an output port 37 which are connected to each other via a bidirectional bus 32. .

  The output signal of the air flow meter 16 is input to the input port 36 via the corresponding AD converter 38. A load sensor 41 is connected to the accelerator pedal 40. The load sensor 41 generates an output voltage proportional to the depression amount of the accelerator pedal 40. This output voltage is input to the input port 36 via the corresponding AD converter 38.

  The crank angle sensor 42 generates an output pulse each time the crankshaft rotates, for example, a predetermined angle, and this output pulse is input to the input port 36. The engine speed can be detected from the output of the crank angle sensor 42. Further, the crank angle can be detected from the output of the crank angle sensor 42. In the engine exhaust passage, a temperature sensor 43 as a temperature detector that detects the temperature of the exhaust treatment device 21 is disposed downstream of the exhaust treatment device 21. The output of the temperature sensor 43 is input to the input port 36 via the corresponding AD converter 38.

  The output port 37 of the electronic control unit 31 is connected to the fuel injection valve 11 and the spark plug 10 via the corresponding drive circuits 39. The electronic control unit 31 in the present embodiment is formed to perform fuel injection control and ignition control. That is, the fuel injection timing and the fuel injection amount are controlled by the electronic control unit 31. Further, the ignition timing of the spark plug 10 is controlled by the electronic control unit 31. The output port 37 is connected to a step motor 17 and a fuel pump 29 that drive the throttle valve 18 via a corresponding drive circuit 39. These devices are controlled by the electronic control unit 31.

  The intake valve 6 is formed to open and close as the intake cam 51 rotates. The exhaust valve 8 is formed to open and close as the exhaust cam 52 rotates. The internal combustion engine in the present embodiment includes a variable valve mechanism. The variable valve mechanism includes a variable valve timing device 53 that changes the opening / closing timing of the intake valve 6. The variable valve timing device 53 in the present embodiment is connected to the rotation shaft of the intake cam 51. The variable valve timing device 53 is controlled by the electronic control unit 31.

  The internal combustion engine in the present embodiment includes a variable compression ratio mechanism. In the present invention, the space in the cylinder surrounded by the crown surface of the piston and the cylinder head when the piston reaches compression top dead center is referred to as a combustion chamber. The compression ratio of the internal combustion engine is determined depending on the volume of the combustion chamber and the like. The variable compression ratio mechanism in the present embodiment is formed to change the compression ratio by changing the volume of the combustion chamber. The actual compression ratio, which is the actual compression ratio in the combustion chamber, is expressed by (actual compression ratio) = (combustion chamber volume + piston stroke volume when the intake valve is closed) / (combustion chamber volume).

  FIG. 2 shows a first schematic cross-sectional view of the internal combustion engine variable compression ratio mechanism according to the present embodiment. FIG. 2 is a schematic view when a high compression ratio is achieved by the compression ratio variable mechanism. FIG. 3 shows a second schematic cross-sectional view of the compression ratio variable mechanism of the internal combustion engine in the present embodiment. FIG. 3 is a schematic view when the compression ratio is changed by the variable compression ratio mechanism.

  With reference to FIGS. 1 to 3, in the internal combustion engine in the present embodiment, the support structure including crankcase 79 and cylinder block 2 disposed on the upper side of the support structure move relative to each other. The support structure in the present embodiment supports the cylinder block 2 via a compression ratio variable mechanism. Further, the support structure in the present embodiment supports the crankshaft 24 so as to be rotatable on one rotating shaft.

  A plurality of protrusions 80 are formed below the side walls on both sides of the cylinder block 2. A cam insertion hole having a circular cross section is formed in the projecting portion 80, and a circular cam 86 is rotatably disposed inside the cam insertion hole. A plurality of protrusions 82 are formed on the crankcase 79. A cam insertion hole having a circular cross section is formed in the projecting portion 82, and a circular cam 88 is rotatably disposed inside the cam insertion hole. The protrusion 80 of the cylinder block 2 is fitted between the protrusions 82 of the crankcase 79.

  The circular cam 86 inserted into the protruding portion 80 of the cylinder block 2 and the circular cam 88 inserted into the protruding portion 82 of the crankcase 79 are connected to each other via an eccentric shaft 87. A plurality of circular cams 86 and a plurality of circular cams 88 are connected via an eccentric shaft 87 to form camshafts 84 and 85. In the present embodiment, a pair of camshafts 84 and 85 are formed. The compression ratio variable mechanism in the present embodiment includes a rotating device that rotates the pair of camshafts 84 and 85 in opposite directions. The circular cam 88 is arranged coaxially with the rotation axis of the cam shafts 84 and 85. The circular cam 86 is eccentric with respect to the rotation axis of the cam shafts 84 and 85. Further, the eccentric shaft 87 is eccentric with respect to the rotation axis of the camshafts 84 and 85.

  Referring to FIG. 2, when the circular cams 88 arranged on the respective camshafts 84 and 85 are rotated in opposite directions as indicated by arrows 97, the eccentric shaft 87 faces the upper end of the circular cam 88. Move. The circular cam 86 supporting the cylinder block 2 rotates in the opposite direction to the circular cam 88 as indicated by an arrow 96 inside the cam insertion hole. The cylinder block 2 moves in a direction away from the crankcase 79 as indicated by an arrow 98.

  As shown in FIG. 3, when the eccentric shaft 87 moves to the upper end of the circular cam 88, the central axis of the circular cam 88 moves below the eccentric shaft 87. Referring to FIGS. 2 and 3, the relative position between crankcase 79 and cylinder block 2 is determined by the distance between the central axis of circular cam 86 and the central axis of circular cam 88. As the distance between the central axis of the circular cam 86 and the central axis of the circular cam 88 increases, the cylinder block 2 moves away from the crankcase 79. The volume of the combustion chamber 5 increases as the cylinder block 2 moves away from the crankcase 79.

  In the compression ratio variable mechanism in the present embodiment, the volume of the combustion chamber 5 is variably formed by moving the cylinder block 2 relative to the crankcase 79. In the present embodiment, a compression ratio determined only from the stroke volume of the piston from the bottom dead center to the top dead center and the volume of the combustion chamber is referred to as a mechanical compression ratio. The mechanical compression ratio is represented by (mechanical compression ratio) = (combustion chamber volume + piston stroke volume) / (combustion chamber volume) without depending on the closing timing of the intake valve.

  In the state shown in FIG. 2, the volume of the combustion chamber 5 is small, and the compression ratio is high when the intake air amount is always constant. This state is a state where the mechanical compression ratio is high. In contrast, in the state shown in FIG. 3, the volume of the combustion chamber 5 is large, and the compression ratio is low when the intake air amount is always constant. This state is a state where the mechanical compression ratio is low. Thus, the internal combustion engine in the present embodiment can change the compression ratio during the operation period. For example, the compression ratio can be changed by a variable compression ratio mechanism according to the operating state of the internal combustion engine.

  The variable compression ratio mechanism according to the present embodiment moves the cylinder block relative to the crankcase by rotating a circular cam having an eccentric rotation shaft. However, the present invention is not limited to this configuration. Any mechanism that moves the cylinder block relative to the support structure that supports the cylinder can be employed.

  2 and 3, the internal combustion engine in the present embodiment has a portion in which crankcase 79 and cylinder block 2 slide in contact with each other. The crankcase 79 in the present embodiment includes a cover portion 72 formed so as to cover the protruding portion 82 of the crankcase 79 and the protruding portion 80 of the cylinder block 2. The cover part 72 is formed so as to cover a part of the cylinder block 2 from the side. The cover 72 is formed so as to surround the side surface of the cylinder block 2. The cover 72 is in contact with the side surface of the cylinder block 2.

  In the internal combustion engine in the present embodiment, when the compression ratio changes, the cover portion 72 of the crankcase 79 and the cylinder block 2 slide. In order to seal between the crankcase 79 and the cylinder block 2, a boot seal 73 is arranged as a seal member. Both ends of the boot seal 73 are fixed to the end of the cover 72 and the side surface of the cylinder block 2. By disposing the boot seal 73 between the support structure including the crankcase 79 and the cylinder block 2, it is possible to suppress the gas inside the crankcase 79 from flowing out of the internal combustion engine.

  The boot seal 73 in the present embodiment is formed in an annular shape so as to surround the side surface of the cylinder block 2. The boot seal 73 is deformed as the mechanical compression ratio is changed. The boot seal 73 is formed of a material that can be deformed with a change in the mechanical compression ratio. For example, the boot seal 73 is made of rubber or resin. As a sealing member, it is not restricted to this form, The arbitrary members which have a sealing function are employable.

  FIG. 4 is a schematic cross-sectional view for explaining the blow-by gas reduction device for an internal combustion engine in the present embodiment. The engine body 1 in the present embodiment includes a support structure that supports the crankshaft 24. The support structure in the present embodiment includes a crankcase 79 and an oil pan 70. The piston 3 is supported on the crankshaft 24 via a connecting rod 23. The crankcase 79 accommodates the crankshaft 24 inside. The oil pan 70 is disposed below the crankcase 79. Oil 71 that lubricates each component of the engine body 1 is stored at the bottom of the oil pan 70. In the present embodiment, oil 71 is stored at the bottom of oil pan 70. The oil 71 is supplied to each part of the engine body 1 by an oil pump, for example.

  An oil passage 61 through which oil flows is formed inside the cylinder head 4. Oil that has lubricated the components arranged in the cylinder head 4 collects in the oil passage 61. An oil passage 62 is formed in the cylinder block 2. The oil passage 62 communicates with the oil passage 61. An oil passage 63 is formed in the crankcase 79. The oil passage 63 is formed so that oil that has flowed out from the oil passage 62 into the cover portion 72 flows into the oil passage 63. The oil that has lubricated the components arranged in the cylinder head 4 is returned to the bottom of the oil pan 70 through the oil passages 61, 62, and 63.

  The internal combustion engine in the present embodiment includes a blow-by gas reduction device as blow-by gas reduction means for returning blow-by gas flowing out between the hole of the cylinder block 2 and the piston 3 to the engine intake passage. In the space inside the crankcase 79, blow-by gas flows out from the inside of the cylinder including the combustion chamber 5. The blow-by gas reduction device ventilates the inside of the crankcase 79. The cylinder head 4 is covered with a cylinder head cover 57. The cylinder head cover 57 is fixed to the cylinder head 4.

  The blow-by gas reduction device in the present embodiment includes an air circulation pipe 65 that supplies fresh air from the engine intake passage. The air circulation pipe 65 is connected to the space inside the cylinder head cover 57. In the present embodiment, the air circulation pipe 65 is connected upstream of the throttle valve 18 in the intake duct 15.

  The blow-by gas reduction apparatus in the present embodiment includes a PCV (Positive Crankcase Ventilation) valve 64 and a return pipe 66 that returns a gas containing blow-by gas to the engine intake passage. The return pipe 66 in the present embodiment is connected to the space inside the cylinder head cover 57 via the PCV valve 64. The return pipe 66 is connected to the engine intake passage. The return pipe 66 is connected to the downstream side of the throttle valve 18. The return pipe 66 in the present embodiment is connected downstream of the surge tank 14. For example, the PCV valve 64 is formed to open when the difference between the pressure inside the crankcase 79 and the pressure inside the intake duct 15 becomes larger than a predetermined pressure difference.

  The crankcase 79 is formed with a blowby gas passage 91 through which a gas containing blowby gas inside the crankcase 79 is circulated. The cylinder block 2 is formed with a blow-by gas passage 92 through which a gas containing blow-by gas is circulated, and the cylinder head 4 is formed with a blow-by gas passage 93. Each blow-by gas passage 91, 92, 93 supplies the gas inside the crankcase 79 to the return pipe 66.

  When the internal combustion engine is driven, the pressure is lower than the atmospheric pressure in the engine intake passage downstream of the throttle valve 18. For this reason, the gas inside the crankcase 79 can be sucked into the engine intake passage via the return pipe 66. In the present embodiment, the gas including the blow-by gas inside the crankcase 79 flows into the blow-by gas passage 91 as indicated by an arrow 67. Further, the gas containing blow-by gas is supplied into the cylinder head cover 57 through the space inside the cover portion 72 and the blow-by gas passages 92 and 93. The gas including the blow-by gas is sucked into the engine intake passage through the PCV valve 64 and the return pipe 66 as indicated by an arrow 68. The PCV valve 64 adjusts the flow rate of gas including blow-by gas returned to the engine intake passage. The gas supplied to the engine intake passage is supplied again to the combustion chamber 5 through the engine intake passage. In the combustion chamber 5, unburned gas contained in blow-by gas can be burned.

  When the air inside the crankcase 79 is sucked into the engine intake passage, the inside of the crankcase 79 becomes negative pressure. When the pressure inside the crankcase 79 is reduced, unburned gas and air containing no burned gas are supplied to the inside of the crankcase 79 through the air circulation pipe 65 and the oil passages 61, 62, 63. The That is, fresh air that does not contain blow-by gas is supplied to the space inside the crankcase 79 as indicated by an arrow 69.

  As described above, when the internal combustion engine is driven, the gas including the blow-by gas inside the crankcase 79 is supplied to the engine intake passage through the blow-by gas passages 91, 92, 93 and the return pipe 66. On the other hand, fresh air is supplied to the inside of the crankcase 79 through the air circulation pipe 65 and the oil passages 61, 62, 63, and the space inside the crankcase 79 can be ventilated.

  The internal combustion engine in the present embodiment includes pulsation detecting means for detecting pulsation of gas containing blow-by gas. The pulsation detecting means in the present embodiment includes a pressure sensor 75 that detects the pressure inside the crankcase 79. The output of the pressure sensor 75 is input to the electronic control unit 31. The pressure sensor 75 can detect the pulsation of the pressure of the gas including the blow-by gas inside the crankcase 79. As a pulsation detection means, it is not restricted to this form, The arbitrary apparatuses which detect the pulsation of the gas containing blowby gas are employable.

  Next, operation control of the internal combustion engine in the present embodiment will be described. The operation control of the present embodiment performs control to suppress pulsation of gas containing blowby gas during the operation period of the internal combustion engine. The internal combustion engine in the present embodiment suppresses pulsation by changing the mechanical compression ratio when pulsation of gas containing blow-by gas is detected.

  FIG. 5 shows a time chart of the first operational control in the present embodiment. Until time t0, the pressure Pcc inside the crankcase 79 gradually increases. At time t0, pressure pulsation inside the crankcase 79 occurs. That is, the pressure of the gas containing blow-by gas is pulsating.

  The internal combustion engine detects pulsation of gas containing blow-by gas and performs control to change the mechanical compression ratio ε at time t1. In the example shown in FIG. 5, control for increasing the mechanical compression ratio ε is performed. In changing the mechanical compression ratio ε, control for reducing the mechanical compression ratio may be performed. Further, when the mechanical compression ratio ε is increased, it is possible to perform control for retarding the ignition timing because knocking may occur.

  In the example shown in FIG. 5, the mechanical compression ratio is increased by the change amount Δε. Further, the ignition timing is retarded by a retard amount ΔSA1. By changing the mechanical compression ratio, the shape and volume of the space inside the crankcase 79 can be changed, and the pulsation of gas containing blow-by gas inside the crankcase 79 can be suppressed.

  By the way, if the mechanical compression ratio is changed in the increasing direction, knocking may be induced by pressure propagation inside the combustion chamber 5 (inside the cylinder) in the direction in which the piston moves. Further, for example, knocking may occur when the ignition timing is delayed. Once knocking occurs, the temperature of the piston or the like rises, and knocking may continue even if the retard amount of the ignition timing is set to a predetermined retard amount.

  For this reason, in the first operational control of the present embodiment, when the mechanical compression ratio is changed in the increasing direction, the ignition timing is temporarily delayed more excessively. That is, the ignition timing is undershooted. When the mechanical compression ratio is changed, the occurrence of knocking can be more reliably suppressed by excessively retarding the ignition timing. In the present embodiment, an excessive retardation of the retardation amount ΔSA2 is performed to control to lower the piston temperature. In the present embodiment, ignition control is performed with a retard amount obtained by adding the retard amount ΔSA2 to the retard amount ΔSA1 temporarily.

  As the change amount Δε of the mechanical compression ratio, the retardation amount ΔSA1 of the ignition timing, and the retardation amount ΔSA2 for excessive retardation, preset values can be adopted. After the ignition timing is excessively retarded, the retardation amount ΔSA2 can be advanced to set the ignition timing retarded by the retardation amount ΔSA1.

  FIG. 6 shows a flowchart of the first operation control in the present embodiment. The operation control shown in FIG. 6 can be performed at predetermined time intervals, for example.

  In step 101, the pressure Pcc inside the plurality of crankcases 79 during a predetermined period is detected. The pressure Pcc inside the crankcase 79 can be detected by the pressure sensor 75.

  FIG. 7 shows a graph of the gas pressure inside the crankcase. The horizontal axis represents time, and the vertical axis represents the pressure Pcc inside the crankcase. In the present embodiment, the pressure Pcc is detected at predetermined time intervals. The detected pressure Pcc can be stored in the electronic control unit 31.

  In the present embodiment, the (k−j) th pressure Pcc at the past time ty is used from the kth pressure Pcc at the current time tx. At this time, the time length from time ty to time tx or the number of pressures Pcc used for calculation can be determined in advance. The time interval for detecting the pressure Pcc is preferably a time sufficiently shorter than one cycle of the pressure vibration inside the crankcase 79. By adopting such a time interval, the amplitude of the pressure inside the crankcase 79 can be calculated more accurately.

  Referring to FIGS. 6 and 7, next, in step 102 to step 104, it is determined whether or not pulsation is generated in the gas containing blow-by gas. In the present embodiment, the magnitude of the pulsation of the gas pressure inside the crankcase 79 is detected, and if the magnitude of the pulsation of the gas pressure is greater than a predetermined determination value, the mechanical compression ratio The control which changes is performed.

  In step 102, the maximum value of the pressure Pcc in the crankcase 79 is calculated. The maximum value Pcc, max of the pressure in the crankcase 79 can be selected from the detected plurality of pressures Pcc (k−j), Pcc (k−j + 1),..., Pcc (k). it can.

  Next, in step 103, the minimum value of the pressure Pcc in the crankcase 79 is calculated. As the minimum pressure values Pcc and mim in the crankcase 79, the minimum value among the detected pressures Pcc (k−j), Pcc (k−j + 1),..., Pcc (k) can be selected. it can.

  Next, in step 104, the pulsation amplitude of the pressure Pcc in the crankcase is estimated, and it is determined whether or not the estimated pulsation amplitude is larger than a predetermined determination value δpcc. That is, it is determined whether or not the magnitude of the pulsation of the blow-by gas pressure is greater than a predetermined determination value. The variable (| Pcc, max−Pcc, mim | / 2) calculates one half of the difference between the maximum value and the minimum value of the actually measured pressure in the crankcase. That is, the maximum value of the amplitude of the pressure Pcc is calculated based on the actually measured pressure. The determination value δpcc corresponds to the pressure amplitude when determining that the pulsation is large.

  In step 104, when the maximum value of the amplitude of the pressure Pcc is equal to or smaller than a predetermined determination value δpcc, this control is terminated. In this case, it can be determined that the pressure pulsation of the gas containing blow-by gas is small. This control is terminated without performing the control for increasing the mechanical compression ratio in the present embodiment.

  In step 104, when the maximum value of the amplitude of the pressure Pcc in the crankcase is larger than a predetermined determination value δpcc, the routine proceeds to step 105. In this case, it can be determined that the pulsation of the pressure of the gas containing blow-by gas is large.

  In step 105, it is determined whether the current mechanical compression ratio is in the high compression ratio side region or the low compression ratio side region. The pulsation of the gas containing blow-by gas can be suppressed whether the mechanical compression ratio is lowered or increased. In the control of the present embodiment, the mechanical compression ratio is changed to the side where the changeable range of the mechanical compression ratio is large. When the current mechanical compression ratio is within the region on the high compression ratio side, control is performed to lower the mechanical compression ratio. When the current mechanical compression ratio is within the region on the low compression ratio side, control is performed to increase the mechanical compression ratio.

  In step 105, an intermediate value between the maximum mechanical compression ratio εmax and the minimum mechanical compression ratio εmim is calculated in an area where the mechanical compression ratio can be changed. It is determined whether or not the current mechanical compression ratio ε is larger than the calculated intermediate value. When the current mechanical compression ratio ε is larger than the intermediate value of the mechanical compression ratio, the routine proceeds to step 106. In this case, control is performed to change the mechanical compression ratio so that the mechanical compression ratio becomes smaller.

  In step 106, a target mechanical compression ratio is set. A target mechanical compression ratio ε is calculated by subtracting a predetermined mechanical compression ratio change Δε from the current mechanical compression ratio. A preset value can be adopted as the change amount Δε of the mechanical compression ratio. Next, in step 107, control is performed to change the mechanical compression ratio to the target mechanical compression ratio ε. When reducing the mechanical compression ratio, the internal combustion engine shifts to a state where knocking is unlikely to occur. Therefore, it is not necessary to change the ignition timing.

  Next, in step 105, when the current mechanical compression ratio ε is equal to or smaller than the intermediate value of the mechanical compression ratio, the routine proceeds to step 108. In this case, the mechanical compression ratio is changed to increase. In step 108, the target mechanical compression ratio ε is set by adding the change amount Δε of the mechanical compression ratio to the current mechanical compression ratio ε. A preset value can be adopted as the change amount Δε of the mechanical compression ratio.

  Next, in step 109, it is determined whether or not it is within the region where knocking occurs. That is, it is determined whether or not knocking occurs by performing control to increase the mechanical compression ratio. In the control example shown in FIG. 6, when it is determined that knocking occurs, control for excessively retarding the ignition timing is adopted, and when it is determined that knocking does not occur, excessive ignition timing is employed. The control which does not perform a slow retardation is adopted.

  Whether or not it is a region where knocking occurs can be determined based on, for example, the charging efficiency KL and the engine speed NE. The charging efficiency KL can be calculated by a map or the like based on the opening of the throttle valve, for example. In an internal combustion engine, knocking is more likely to occur as the charging efficiency increases, and knocking is less likely to occur as the engine speed increases. For this reason, for example, when the charging efficiency is high and the engine speed is low, it can be determined that the region is where knocking occurs. If it is determined in step 109 that the region is where knocking occurs, the process proceeds to step 110.

  In step 110, an ignition timing SA obtained by retarding the retard amount ΔSA1 of the ignition timing and the excess retard amount ΔSA2 from the current ignition timing SA is calculated. That is, the target ignition timing SA that is excessively retarded is set.

  Next, in step 111, the mechanical compression ratio is changed to the mechanical compression ratio ε set in step 108. Further, the ignition timing is changed to the ignition timing SA set in step 110. Here, control is performed to undershoot the ignition timing.

  Next, at step 112, the ignition timing SA obtained by retarding the retardation amount ΔSA1 from the reference ignition timing SA is calculated by adding the excess retardation amount ΔSA2 to the current ignition timing SA. That is, the ignition timing SA when the undershoot is not performed is calculated.

  Next, in step 113, the ignition timing is changed to the ignition timing SA calculated in step 112. In step 113, the ignition timing can be changed after elapse of a predetermined time from the change in mechanical compression ratio and ignition timing in step 111. With this control, it is possible to change the mechanical compression ratio while suppressing knocking that occurs when the mechanical compression ratio is changed.

  If it is determined in step 109 that the operating state of the internal combustion engine is not in a region where knocking occurs, the routine proceeds to step 114. In this case, the ignition timing is retarded without excessive retardation. In step 114, a target ignition timing SA obtained by retarding the retardation amount ΔSA1 from the current ignition timing is set.

  Next, in step 115, the mechanical compression ratio is changed to the mechanical compression ratio ε set in step 108. The ignition timing is changed to the ignition timing SA set in step 114. In this case, since the operating state of the internal combustion engine is out of the region where knocking occurs, the ignition timing is retarded without undershooting.

  Thus, when the pulsation of the gas containing blow-by gas is large, the mechanical compression ratio can be changed to suppress the pulsation. In the first operation control, when the magnitude of the pulsation of the gas containing blow-by gas is larger than a predetermined determination value, control is performed to change the mechanical compression ratio, but not limited to this form. When it is determined that pulsation is generated in the gas containing blow-by gas, it is possible to perform control to change the mechanical compression ratio.

  Predetermined values are adopted for the change amount Δε of the mechanical compression ratio and the retard amount ΔSA1, ΔSA2 of the ignition timing in the present embodiment, but the present invention is not limited to this form, and variable values can be adopted. . For example, the control may be performed to set the change amount Δε of the mechanical compression ratio and the retardation amounts ΔSA1, ΔSA2 of the ignition timing in accordance with the detected pulsation magnitude. As the pulsation of the gas including the blow-by gas increases, it is possible to perform control to increase the change amount of the mechanical compression ratio and the retard amount of the ignition timing.

  By the way, in an internal combustion engine equipped with a supercharger, pressurized air is supplied to the combustion chamber, and the pressure in the combustion chamber increases when the piston reaches compression top dead center. For this reason, the pressure of the gas containing blow-by gas inside the crankcase also increases. Since pulsation is more likely to occur as the gas density is higher, pulsation of gas containing blow-by gas is also likely to occur. Therefore, the control for suppressing pulsation of the present embodiment is particularly suitable for an internal combustion engine including a supercharger.

  Next, the second operation control of the present embodiment will be described with reference to FIGS. 8 and 9. Referring to FIG. 5, in the first operation control, the mechanical compression ratio is changed and the ignition timing is retarded at time t1. At this time, in order to retard the ignition timing, an impact due to output fluctuation may occur. In particular, the driver may feel an unintended impact, that is, a torque shock. For example, at time t1, the output torque decreases in accordance with the change in the ignition timing. When the torque change at this time is large, the driver may feel a torque shock.

  FIG. 8 shows a time chart of the second operational control of the present embodiment. In the second operational control of the present embodiment, when an impact due to output fluctuation is detected, control is performed to make the speed for changing the next mechanical compression ratio and the speed for changing the ignition timing slower than the current speed. Do.

  The internal combustion engine of the present embodiment includes an impact detection means for detecting an impact due to output fluctuation. The impact detection means in the present embodiment detects whether or not an impact has occurred based on the driver's operation. When a torque shock occurs, the driver's operation may be affected. For example, when the driver feels a torque shock, the amount of depression of the accelerator pedal is temporarily reduced. The impact detection means of the present embodiment detects the depression amount of the accelerator pedal, the depression amount of the brake pedal, and the steering amount of the steering. If at least one of these output signals is large, the impact due to the fluctuation of the output is detected. Is determined to have occurred. In FIG. 8, the amount of depression of the accelerator pedal is illustrated.

  At time t1, the mechanical compression ratio ε is increased by the change amount Δε, and the ignition timing is retarded by the retard amount ΔSA1. In the example shown in FIG. 8, the ignition timing is retarded by the retardation amount ΔSA2. At time t1, the amount of depression of the accelerator pedal increases after it temporarily decreases. In the present embodiment, the rate of change in the amount of depression of the accelerator pedal is detected, and when the rate of change in the amount of depression is greater than a predetermined determination value, it is determined that an impact due to output fluctuation has occurred. ing.

  Thereafter, the operation of the internal combustion engine is continued, and the pulsation of the gas containing blow-by gas occurs again. At time t2, the mechanical compression ratio ε is increased and the ignition timing SA is retarded. The change amount Δε of the mechanical compression ratio at this time is the same as the change amount Δε of the mechanical compression ratio at time t1. Similarly, the retard amount of the ignition timing is the same as the retard amount ΔSA1 of the ignition timing at time t1.

  Here, since the impact due to the fluctuation of the output occurred in the control at time t1, in the control at time t2, the speed for changing the mechanical compression ratio and the speed for changing the ignition timing are slower than the speed at the previous time t1. doing. In the control at the previous time t1, the mechanical compression ratio ε and the ignition timing SA are changed during the time length TL1. In the current control at time t2, the mechanical compression ratio ε and the ignition timing SA are changed during a time length TL2 longer than the time length TL1. The change amount Δε of the mechanical compression ratio and the retardation amount ΔSA1 of the ignition timing are the same, but the time for changing the mechanical compression ratio ε and the time for changing the ignition timing SA are increased. Control is performed to gradually change the mechanical compression ratio ε and the ignition timing SA.

  As shown in FIG. 8, the change rate of the depression amount of the accelerator pedal when the mechanical compression ratio ε and the ignition timing SA are changed at time t2 is smaller than the change rate of the depression amount at the previous time t1. Thus, it can be seen that the uncomfortable torque shock felt by the driver is reduced by performing the control of gradually changing the mechanical compression ratio and the ignition timing.

  In the example of the operation control shown in FIG. 8, it is determined that the accelerator pedal depression amount is temporarily small even when the mechanical compression ratio and the ignition timing are changed at time t2, and the driver feels a torque shock. be able to. That is, it can be determined that an impact due to output fluctuation has occurred. For this reason, in the next change of the mechanical compression ratio ε and ignition timing SA at time t3, the speed for changing the mechanical compression ratio and the speed for changing the ignition timing are further slowed down. That is, the control is performed such that the time length TL3 for changing the mechanical compression ratio ε and the ignition timing SA is longer than the control time length TL2 at time t2. By performing this control, it is possible to further suppress an impact caused by fluctuations in output.

  At time t3, it can be determined that there is no change in the amount of depression of the accelerator pedal when the mechanical compression ratio ε and the ignition timing SA are changed, and that there is no impact due to output fluctuation. When the mechanical compression ratio ε and the ignition timing SA are changed after time t3, the mechanical compression ratio ε and the ignition timing SA can be changed by the time length TL3.

  As described above, when it is determined that the impact due to the fluctuation of the output is generated in the current change in the mechanical compression ratio and the ignition timing, the change speed of the mechanical compression ratio and the ignition timing is decreased in the next control. Can do.

  In the present embodiment, the mechanical compression ratio and the ignition timing are changed over a plurality of times. By greatly changing the mechanical compression ratio and the ignition timing at once, it is possible to reliably suppress an impact caused by fluctuations in output. However, if the mechanical compression ratio and the ignition timing are greatly changed at a time, the period for changing the mechanical compression ratio and the ignition timing becomes long, and the time during which the pulsation of the gas including blow-by gas is generated becomes long. As in the present embodiment, by changing the mechanical compression ratio and the ignition timing in small increments over a plurality of times, it is possible to avoid an unnecessarily long period for changing the mechanical compression ratio and the ignition timing.

  In the example of operation control shown in FIG. 8, it is determined whether or not an impact due to output fluctuation has occurred based on the amount of depression of the accelerator pedal. However, the present invention is not limited to this mode. For example, the amount of depression of the brake pedal, It is possible to determine whether or not an impact due to output fluctuation has occurred by detecting the switching of the brake pedal from off to on. For example, when the rate of change of the brake pedal depression amount changes more than a predetermined judgment value or when the brake pedal is depressed from a state where the brake pedal is not depressed, It can be determined that an impact has occurred.

  Alternatively, based on the steering angle of the steering, it may be detected whether or not an impact due to output fluctuation has occurred. For example, when changing the mechanical compression ratio, if the rate of change of the steering angle of the steering changes more than a predetermined determination value, it can be determined that an impact due to output fluctuation has occurred.

  FIG. 9 shows a flowchart of the second operational control of the present embodiment. In the example shown in FIG. 9, it is determined whether or not an impact due to output fluctuation has occurred based on the steering angle θstr of the steering wheel, the accelerator pedal depression amount Xacc, and the brake pedal depression amount Xbrk.

  In step 121, it is detected that the mechanical compression ratio ε and the ignition timing SA have been changed. For example, in the first operation control, it is detected that the mechanical compression ratio ε is increased and the ignition timing SA is retarded.

  Next, in step 122, it is determined whether or not the amount of change in the steering angle θstr of the steering wheel in the time width Δt is larger than a predetermined determination value δstr. That is, it is determined whether or not the driver is operating the steering to be larger than a predetermined determination value. As the time t, the time when the mechanical compression ratio is changed can be adopted. A difference between the steering angle θstr (t) of the steering at time t and the steering angle θstr (t + Δt) of the steering after the time width Δt has elapsed is calculated. It is determined whether or not this difference is larger than a determination value δstr. When the amount of change in the steering angle of the steering wheel over the time width Δt is larger than a predetermined determination value δstr, it can be determined that an impact due to output fluctuation has occurred. In this case, the process proceeds to step 126.

  In step 126, control is performed to reduce the speed of changing the next mechanical compression ratio and the speed of changing the next ignition timing. In the present embodiment, a flag for lowering the speed of changing the mechanical compression ratio and the ignition timing is set to “1”. The initial value of this flag is set to “0”. This flag is read when changing the next mechanical compression ratio ε and ignition timing SA. When this flag is 1, the changing speed of the mechanical compression ratio ε and the changing speed of the ignition timing SA can be made slower than the previous time. For example, the time during which the mechanical compression ratio is increased and the time during which the ignition timing is retarded can be made longer by a predetermined amount than the previous time. On the other hand, when this flag is 0, the changing speed of the mechanical compression ratio ε and the changing speed of the ignition timing SA can be made the same as the previous time.

  In step 122, when the amount of change in the steering angle θstr of the steering wheel in the time width Δt is predetermined but not greater than the determination value δstr, the process proceeds to step 123.

  In step 123, it is determined whether or not the depression amount Xacc of the accelerator pedal 40 in the time width Δt is larger than the determination value δacc. The difference between the depression amount Xacc (t) of the accelerator pedal 40 at time t and the depression amount Xacc (t + Δt) of the accelerator pedal 40 after the lapse of the time width Δt is calculated, and this difference is calculated from a predetermined determination value δacc. It is also determined whether or not it is larger. When the change amount of the accelerator pedal depression amount in the time width Δt is larger than a predetermined determination value δacc, it can be determined that an impact due to the fluctuation of the output has occurred. In this case, the process proceeds to step 126, and control is performed to slow down the change speed when the mechanical compression ratio and ignition timing are changed next time.

  In step 123, if the change amount of the accelerator pedal depression amount in the time width Δt is equal to or smaller than a predetermined determination value δacc, the process proceeds to step 124.

  In step 124, as with the accelerator pedal depression amount in step 123, the amount of change in the brake pedal depression amount Xbrk in the time width Δt is detected. If the amount of change in the amount of depression of the brake pedal is greater than a predetermined determination value δbrk, it can be determined that an impact due to output fluctuation has occurred. In this case, the process proceeds to step 126, and control is performed to slow down the change speed when the mechanical compression ratio and ignition timing are changed next time.

  In step 124, when the amount of change in the amount of depression of the brake pedal in the time width Δt is equal to or smaller than a predetermined determination value δbrk, the process proceeds to step 125. In this case, when the mechanical compression ratio is changed in the current control, it can be determined that there is no impact due to output fluctuation. For this reason, the mechanical compression ratio and the ignition timing can be changed at the same changing speed as in the current control even in the next change in the mechanical compression ratio and the ignition timing. In step 125, a flag for lowering the next changing speed of the mechanical compression ratio ε and the changing speed of the ignition timing SA is set to “0”.

  In step 124 of the present embodiment, the amount of change in the amount of depression of the brake pedal is detected. However, the present invention is not limited to this configuration, and it is determined whether the brake pedal is switched from a state where it is not depressed to a state where it is depressed. It doesn't matter. That is, in step 124, when the state is shifted from the state where the brake pedal is not depressed to the depressed state, it can be determined that an impact due to the fluctuation of the output has occurred. In this case, the process can proceed to step 126.

  In this way, the impact detection means of the present embodiment determines whether or not an impact has occurred based on at least one of the output signal of the accelerator pedal, the output signal of the brake pedal, and the output signal of the steering. Judging. The impact detection means is not limited to this form, and any device capable of detecting an impact due to output fluctuation can be employed. For example, the impact detection means includes a vibration sensor disposed in the engine body, and when the magnitude of vibration generated when the mechanical compression ratio and the ignition timing are changed becomes larger than a predetermined vibration determination value. It may be determined that a torque shock has occurred.

  In the second operational control of the present embodiment, the control for increasing the mechanical compression ratio and retarding the ignition timing has been described as an example. However, the present invention is not limited to this mode, and control for decreasing the mechanical compression ratio. The same control can be performed also when performing. That is, when control is performed to reduce the mechanical compression ratio and the ignition timing is changed, if it is determined that an impact due to output fluctuation has occurred, control to reduce the speed of changing the mechanical compression ratio is performed in the next control. It can be carried out. Further, it is possible to perform control for reducing the changing speed of the ignition timing.

  Next, the third operation control of the present embodiment will be described. Referring to FIG. 5, in the first operation control of the present embodiment, when the mechanical compression ratio ε is increased and the ignition timing SA is retarded, the output torque is reduced. For this reason, deceleration of the vehicle which is not intended by the driver may occur. In 3rd operation control, control which suppresses the fall of the torque which arises when changing a mechanical compression ratio is performed. The third operation control includes so-called torque reserve control for maintaining the output torque.

  FIG. 10 shows a time chart of the third operational control in the present embodiment. In FIG. 10, the first operation control of the present embodiment is indicated by a broken line, and the third operation control of the present embodiment is indicated by a solid line. The internal combustion engine according to the present embodiment includes an operation region detection unit that detects that the operation state of the internal combustion engine is within an operation region in which there is a possibility that pulsation of gas containing blow-by gas occurs. When the operating state of the internal combustion engine is within an operating region where there is a possibility of pulsation of gas containing blow-by gas, torque reserve control is performed.

  In the present embodiment, torque reserve control is performed when the pressure of the gas including the current blow-by gas is within the pulsation region or the pulsation preparation region near the pulsation region. In the torque reserve control, the ignition timing is retarded and the charging efficiency is increased.

  In the operation example shown in FIG. 10, the pressure in the crankcase reaches the pressure at which pulsation occurs at time t0 before time t1 when the mechanical compression ratio is changed. For this reason, torque reserve control is started at time t0. That is, at the time t0, the ignition timing is retarded and the charging efficiency is increased. In the present embodiment, control for increasing the opening of the throttle valve is performed in order to increase the charging efficiency. Further, in the present embodiment, at time t0, the ignition timing and the charging efficiency are gradually changed without changing instantaneously.

  Thereafter, at time t1, it is determined that the magnitude of the pulsation of the gas pressure in the crankcase is greater than a predetermined determination value. Therefore, at time t1, control for increasing the mechanical compression ratio is performed. In the third operation control, since the ignition timing is retarded in advance, it is not necessary to further retard the ignition timing at time t1, and the output torque can be maintained substantially constant.

  As described above, in the third operation control, the torque reserve control that retards the ignition timing and increases the charging efficiency before changing the mechanical compression ratio is performed, and the output is performed even when the mechanical compression ratio is changed. Torque can be kept almost constant. In the torque reserve control in the present embodiment, the ignition timing margin with respect to knocking is increased by retarding the ignition timing from the original set value. Further, torque variation can be suppressed by changing the charging efficiency when changing the ignition timing.

  FIG. 11 shows a flowchart of the third operational control of the present embodiment. In step 131, the pressure Pcc in the crankcase and the engine speed NE are detected.

  Next, in step 132, a range in which there is a possibility of pulsation in the gas containing blow-by gas is read.

  FIG. 12 shows a graph for explaining a range in which the pulsation of gas containing blow-by gas of the internal combustion engine of the present embodiment may occur. The horizontal axis is the engine speed NE, and the vertical axis is the pressure Pcc in the crankcase. FIG. 12 shows a pulsation region that is a region where pulsation occurs and a pulsation preparation region that is a region around the pulsation region. The range in which pulsation is likely to occur in the gas containing blow-by gas in the present embodiment includes a pulsation region and a pulsation preparation region. It can be seen that the pressure range in the pulsation region increases as the engine speed NE increases. The pulsation region in the present embodiment is a region sandwiched between the maximum pressure Ppuls, max and the minimum pressure Ppuls, mim.

  The pulsation preparation region in the present embodiment is set in order to prevent the operation state of the internal combustion engine from entering the pulsation region when the operation state of the internal combustion engine is changed. For example, a pulsation preparation area is set in order to prevent the operating state of the internal combustion engine from being in the pulsation area during the period after the change of the throttle valve opening until the actual change in charging efficiency is completed. Yes. As described above, the pulsation preparation region of the present embodiment is set in order to avoid being in the pulsation region due to a transient change in the operation state or the like. In the pulsation preparation region of the present embodiment, the maximum pressure is a value obtained by adding the pressure width ΔPcc to the maximum pressure in the pulsation region. In the pulsation preparation area, a value obtained by subtracting the pressure width ΔPcc from the minimum pressure in the pulsation area is set as the minimum pressure. A preset value is adopted as the pressure width ΔPcc in the present embodiment.

  Referring to FIG. 11, in step 132, the maximum pressure Ppuls, max in the pulsation region and the minimum pressure Ppuls, mim in the pulsation region are read. As the maximum pressures Ppuls, max and the minimum pressures Ppuls, mim in the pulsation region, for example, values obtained by using the engine speed as a function can be stored in the electronic control unit 31 in advance.

  Next, in step 133, it is determined whether or not the detected pressure Pcc in the crankcase is in the pulsation region or the pulsation preparation region. That is, it is determined whether or not the pressure Pcc in the crankcase is in a range larger than (Ppuls, mim−ΔPcc) and smaller than (Ppuls, max + ΔPcc).

  In step 133, when the pressure Pcc in the crankcase is within the pulsation region or the pulsation preparation region, the routine proceeds to step 134. When the pressure Pcc in the crankcase is in the pulsation region or the pulsation preparation region, pulsation may occur.

  In step 134, it is determined whether or not torque reserve control has already been performed. If the torque reserve control has already been performed in step 134, this control is terminated. If the torque reserve control is not performed in step 134, the process proceeds to step 135.

  In step 135, torque reserve control is performed. That is, the ignition timing is retarded and the charging efficiency is increased. Here, the retard amount of the ignition timing and the increase amount of the charging efficiency can be carried out in predetermined amounts. Moreover, the ignition timing can be retarded and the charging efficiency can be increased so that the output torque is maintained substantially constant.

  If it is determined in step 133 that the pressure Pcc in the crankcase is not within the pulsation region or the pulsation preparation region, the process proceeds to step 136.

  In step 136, it is determined whether or not torque reserve control is currently being performed. In step 136, when the torque reserve control is not performed, this control is terminated. If it is determined in step 136 that torque reserve control is being performed, the process proceeds to step 137. In this case, the operating state of the internal combustion engine is out of the range where the pulsation of the pressure in the crankcase may occur. Therefore, in step 137, control for stopping the torque reserve control is performed. That is, control is performed to stop the retarding of the ignition timing, stop increasing the charging efficiency, and return to the original operating state.

  Thus, when the internal combustion engine is operated in a predetermined pulsation region or pulsation preparation region, torque reserve control can be performed. By performing the torque reserve control, the output torque can be kept substantially constant even when the mechanical compression ratio is increased in order to suppress the pulsation of the gas containing blow-by gas.

  In the present embodiment, torque reserve control is performed when the operating state of the internal combustion engine is in the pulsation region and the pulsation preparation region. The torque reserve control can also be performed in the entire operation region of the internal combustion engine, for example. However, in this case, the amount of fuel consumption increases. As in the present embodiment, the pulsation region and the pulsation preparation region are set in advance, and when the operating state of the internal combustion engine is in the pulsation region or the pulsation preparation region, the torque reserve control is performed, thereby including blow-by gas. While suppressing the pulsation of gas, the increase in fuel consumption can be suppressed.

  In the third operational control of the present embodiment, the control for increasing the mechanical compression ratio and retarding the ignition timing has been described as an example. However, the present invention is not limited to this mode, and the mechanical compression ratio and the ignition timing are set. The same control can be performed when changing. Moreover, as an operation area | region detection means, it is not restricted to said form, The arbitrary means which can detect having the possibility that the pulsation of the gas containing blowby gas will arise is employable.

  By the way, the pulsation region where the pulsation shown in FIG. 12 occurs can be updated by learning. Next, control for learning a pulsation region in the present embodiment will be described.

  FIG. 13 is a flowchart of control for learning a pulsation region in the internal combustion engine of the present embodiment. The operation control shown in FIG. 13 can be repeatedly performed at predetermined time intervals, for example. Steps 141 to 144 are the same as steps 101 to 104 of the first operation control of the present embodiment (see FIG. 6). Steps 141 to 144 determine whether or not a pulsation having a predetermined magnitude is generated in the gas containing blow-by gas.

  In step 144, if the maximum value of the pulsation amplitude of the pressure Pcc in the crankcase is larger than a predetermined determination value δpcc, the process proceeds to step 145. That is, if it is determined that a pulsation larger than the predetermined magnitude has occurred, the process proceeds to step 145. In step 145, the engine speed NE is detected.

  Next, in step 146, it is determined whether or not the set of the detected engine speed NE and the crankcase pressure Pcc is included in the pulsation region stored in the electronic control unit 31. In step 146, when the set of the engine speed NE and the pressure Pcc in the crankcase is stored as the pulsation region, this control is finished.

  If it is determined in step 146 that the set of the engine speed NE and the pressure Pcc in the crankcase is not included in the pulsation region stored in the electronic control unit 31, the process proceeds to step 147. In step 147, control is performed to add the set of the engine speed NE detected this time and the pressure Pcc in the crankcase to the pulsation region.

  As described above, the control for learning the pulsation region can be performed by adding the operation region in which the pulsation newly occurs to the pulsation region stored in advance in the electronic control unit 31 to update the pulsation region.

  Furthermore, the pulsation preparation area shown in FIG. 12 can be updated by learning. Next, control for updating the pulsation preparation area by learning will be described. In the present embodiment, the pulsation preparation region is set based on the amount of change in pressure in the crankcase when the opening of the throttle valve is changed. In the present embodiment, the pressure width ΔPcc for determining the pulsation preparation region is updated based on the pulsation region.

  FIG. 14 shows a flowchart of control for learning the pulsation preparation region of the internal combustion engine of the present embodiment. In step 151, the start of changing the opening of the throttle valve is detected. In step 152, the pressure Pcc in the crankcase is detected simultaneously with the start of changing the opening of the throttle valve. In step 152, pressures Pcc in the plurality of crankcases are detected at predetermined time intervals.

  Next, in step 153, it is detected whether or not the pressure Pcc in the crankcase is substantially constant. Although the pressure Pcc in the crankcase also changes due to the change in the opening of the throttle valve, it is determined whether or not the pressure Pcc in the crankcase has almost reached a steady state. In step 153, it is determined whether or not the change amount of the pressure Pcc in the crankcase per unit time, that is, the change rate of the pressure Pcc in the crankcase is smaller than a predetermined determination value.

  In step 153, if the rate of change of the pressure Pcc in the crankcase is equal to or greater than a predetermined determination value, it can be determined that the pressure Pcc in the crankcase has not reached a steady state. In this case, the process returns to step 152 to detect the pressure Pcc in the crankcase. In step 153, when the rate of change of the pressure Pcc in the crankcase is smaller than a predetermined determination value, it can be determined that the pressure Pcc in the crankcase has almost reached a steady state. In this case, the process proceeds to step 154.

  In step 154, a change amount ΔPcc of the pressure Pcc due to a change in the opening of the throttle valve is detected. That is, the total change amount of the pressure Pcc in the crankcase from the start of changing the opening of the throttle valve until the pressure Pcc in the crankcase reaches a steady state is detected. This amount of change can be used as the pressure width ΔPcc when setting the pulsation preparation region.

  In step 155, it is determined whether or not the pressure width ΔPcc calculated this time is larger than the currently set pressure width ΔPcc. If the pressure width ΔPcc calculated this time is equal to or smaller than the currently set pressure width ΔPcc, this control is terminated. When the pressure width ΔPcc calculated this time is larger than the currently set pressure width ΔPcc, the routine proceeds to step 156.

  In step 156, control is performed to update the pressure width ΔPcc. That is, the pressure width ΔPcc for setting the pulsation preparation region from the pulsation region is changed to the value calculated this time.

  Thus, in learning of the pulsation preparation region, the amount of change in the pressure in the crankcase when the opening of the throttle valve changes is detected, and when the amount of change is larger than the previous pressure width ΔPcc, pulsation preparation Control for updating the pressure width ΔPcc for setting the region can be performed.

  The above embodiments can be combined as appropriate. In each of the above-described controls, the order of the steps can be appropriately changed within a range where the same function and action can be achieved. In the respective drawings described above, the same or equivalent parts are denoted by the same reference numerals. In addition, said embodiment is an illustration and does not limit invention. In the embodiment, the change shown in a claim is included.

DESCRIPTION OF SYMBOLS 1 Engine body 2 Cylinder block 3 Piston 4 Cylinder head 5 Combustion chamber 10 Spark plug 18 Throttle valve 24 Crankshaft 31 Electronic control unit 40 Accelerator pedal 42 Crank angle sensor 57 Cylinder head cover 61, 62, 63 Oil passage 64 PCV valve 65 Air circulation Pipe 66 Return pipe 75 Pressure sensor 79 Crankcase 86 Circular cam 87 Eccentric shaft 91, 92, 93 Blow-by gas passage

Claims (6)

A support structure for supporting the crankshaft;
A cylinder block including a hole in which the piston is disposed;
A compression ratio variable mechanism that is formed such that the cylinder block moves relative to the support structure and can change the mechanical compression ratio;
Blow-by gas reduction means for returning blow-by gas flowing out between the hole of the cylinder block and the piston to the engine intake passage;
Pulsation detecting means for detecting pulsation of gas containing blowby gas,
An internal combustion engine characterized by changing a mechanical compression ratio when it is determined by a pulsation detecting means that pulsation is generated in a gas containing blowby gas.   The pulsation detecting means detects the magnitude of the pulsation of the pressure of the gas containing the blowby gas, and changes the mechanical compression ratio when the magnitude of the pulsation of the pressure of the gas containing the blowby gas is greater than a predetermined determination value. The internal combustion engine according to claim 1.   3. The internal combustion engine according to claim 1, wherein when it is determined that pulsation is generated in a gas including blowby gas, the internal combustion engine according to claim 1, wherein the mechanical compression ratio is increased and the ignition timing is retarded. Equipped with impact detection means to detect impact due to output fluctuation,
When it is determined that pulsation occurs in the gas containing blow-by gas, it is configured to change the mechanical compression ratio and change the ignition timing,
When the mechanical compression ratio is changed and the ignition timing is changed, when an impact due to output fluctuation is detected, the speed at which the next mechanical compression ratio is changed and the speed at which the ignition timing is changed are changed to the current mechanical compression ratio. The internal combustion engine according to claim 1, wherein the internal combustion engine is slower than a speed at which the speed and ignition timing are changed. A pulsation preparation region having a possibility of causing pulsation of gas containing blowby gas is set in advance,
When the operating state of the internal combustion engine is within a pulsation preparation region, the ignition timing is retarded and the charging efficiency is increased, and the mechanical compression ratio is changed after the ignition timing is retarded and the charging efficiency is increased. The internal combustion engine according to any one of 1 to 4. The support structure includes a crankcase that houses the crankshaft therein.
The internal combustion engine according to any one of claims 1 to 5, wherein the pulsation detecting means includes a pressure sensor that detects a pressure inside the crankcase.

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