JP2010133269A - Intake control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problems: pressure of a decompression tank is gradually increased in association with the repetitive opening/closing operation of an opening and closing valve and a target effect is not provided, in an intake control device formed in such a manner that intake air vacuum in an intake passage is taken into the decompression tank in the non-operation area of a supercharger having a small load with respect to an internal combustion engine; meanwhile, the opening and closing valve is opened/closed in the middle of an intake stroke in the operation area of the supercharger in order to suppress occurrence of knocking. <P>SOLUTION: This intake air control device for the internal combustion engine incorporated with the supercharger includes: a branch passage 41 having one end communicating with an intake passage 24 downstream of the compressor 22 of the supercharger; the decompression tank 43 communicating with the other end of the branch passage 41; the opening and closing valve 45 for opening/closing the branch passage 41; an ECU 33 for controlling the opening/closing operation of the opening and closing valve 45 in conjunction with the opening/closing operation of an intake valve 17; and a decompression means for keeping the inside of the decompression tank 43 at lower pressure than pressure of intake air flowing in the intake passage 24 separately from the opening and closing valve 45. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an intake air control apparatus for an internal combustion engine in which a supercharger is incorporated, and in particular, can suppress the occurrence of knocking associated with a rise in intake air temperature.

  In an internal combustion engine in which a supercharger is incorporated, as the supercharging operation state continues, the intake air temperature gradually rises and the intake air density decreases, so the intake charge efficiency tends to deteriorate gradually. In addition, when the temperature of the intake air is too high, abnormal combustion of the air-fuel mixture, that is, knocking tends to occur frequently.

  In order to solve such a problem, in Patent Document 1, a decompression tank is connected to a midway of an intake passage through a branch passage that branches from here, and an on-off valve incorporated in the middle of the branch passage is connected to an intake air of an internal combustion engine. It proposes a technology that opens and closes in conjunction with the process. That is, in the operation region where the load on the internal combustion engine is small, more specifically, in the non-operating region of the supercharger, the intake negative pressure in the intake passage is taken into the decompression tank and the decompression tank is held in a decompressed state. Then, by opening and closing the on-off valve in the middle of the intake stroke in the knocking occurrence region, more specifically, in the turbocharger operation operation region, the intake pressure charged in the combustion chamber is reduced, and the intake pressure is reduced accordingly. It suppresses the rise in temperature and suppresses the occurrence of knocking.

Japanese Patent Application No. 2008-177889

  However, in the intake control device described in Patent Document 1, if the operation of opening and closing the on-off valve is repeated during the intake stroke in the knocking generation region where the supercharger functions, the pressure in the decompression tank gradually increases. There is a drawback that the target effect gradually increases and fades. Since the volume of the decompression tank is limited, the pressure in the decompression tank is balanced with the pressure in the intake passage in an operation state in which the knocking generation region continues for a long time. As a result, there is a problem in that no effect can be obtained even if the on-off valve is opened and closed during the intake stroke.

  An object of the present invention is to further improve the intake air control device described in Patent Document 1. More specifically, even if the knocking generation area where the turbocharger functions continues for a long time, the pressure increase in the decompression tank is suppressed, thereby continuing the occurrence of knocking. It is an object of the present invention to provide an intake control device that can be blocked.

  An intake control apparatus for an internal combustion engine according to the present invention, in which a supercharger is incorporated, includes a branch passage whose one end communicates with an intake passage downstream of a compressor of the supercharger, and a decompression tank communicated with the other end of the branch passage And an opening / closing valve for opening and closing the branch passage, a control means for controlling the opening / closing operation of the opening / closing valve in conjunction with the opening / closing operation of the intake valve, and the inside of the intake passage separately from the opening / closing valve And a decompression means for holding the inside of the decompression tank at a pressure lower than the pressure of the intake air.

  In the present invention, the inside of the decompression tank is decompressed by the decompression means. When the operating state of the internal combustion engine is not in the non-operating region of the supercharger, the inside of the decompression tank can be decompressed using the intake negative pressure in the intake passage without using this decompression means. When the operating state of the internal combustion engine is in the operating region of the supercharger, the control means opens and closes the on-off valve during the intake stroke of the internal combustion engine, thereby the intake air flowing into the combustion chamber of the internal combustion engine As the pressure decreases, the intake air temperature in the combustion chamber also decreases.

  In the intake control device for an internal combustion engine according to the present invention, the control device further comprises an intake pressure sensor for detecting the pressure in the intake passage, and a pressure sensor for the pressure reducing tank for detecting the pressure in the pressure reducing tank. The on-off valve may be opened and closed based on detection information from the intake pressure sensor and the pressure sensor for the decompression tank.

  The decompression means includes a second branch passage whose one end communicates with the intake passage upstream of the communicating portion with the branch passage, a chamber communicated with the other end of the second branch passage, and a second branch passage. A second opening / closing valve for opening and closing; a communication path communicating the second branch passage between the second opening / closing valve and the chamber and the decompression tank; and a communication path provided in the communication path from the decompression tank side. You may have a non-return valve which permits the flow of gas only to the 2nd branch passage side, and the air release valve which can open | release the inside of a chamber to air | atmosphere. In this case, a chamber pressure sensor for detecting the pressure in the chamber is further provided, and the control means is configured to detect the second on-off valve and the air release valve based on detection information from the chamber pressure sensor and the intake pressure sensor. It may control the opening / closing operation. For example, when the pressure in the intake passage is higher than the pressure in the chamber, the control means preferably opens and closes the second on-off valve. Further, when the pressure in the chamber is higher than a preset pressure, the control means preferably opens and closes the atmosphere release valve.

  Alternatively, the decompression means may include an atmosphere release valve that can open the inside of the decompression tank to the atmosphere, and the control device may control the opening / closing operation of the atmosphere release valve based on detection information from the pressure sensor for the decompression tank. For example, when the pressure in the decompression tank is higher than a preset pressure, for example, atmospheric pressure, the control means preferably opens and closes the air release valve.

  According to the intake control apparatus for an internal combustion engine of the present invention, the pressure reducing means for holding the pressure in the pressure reducing tank at a lower pressure than the pressure of the intake air flowing in the intake passage is provided separately from the opening / closing valve. Can be kept in a state. As a result, even when the operating state of the internal combustion engine continues for a long time and is in the operating region of the supercharger, an excessive pressure rise in the combustion chamber during the intake stroke is prevented and the intake air temperature is reduced. Occurrence can be prevented in advance.

  An intake pressure sensor and a pressure sensor for a decompression tank are provided, and when the control means opens and closes the opening / closing valve based on the detection information from these, the excessive pressure rise in the combustion chamber is prevented during the intake stroke of the internal combustion engine. The intake air temperature can be reduced and knocking can be prevented.

  When the decompression means has the second branch passage, the chamber, the second on-off valve, the communication passage, the check valve, and the air release valve, the internal combustion engine is continuously supercharged by the supercharger. Even in the region, it is possible to prevent an excessive increase in pressure in the combustion chamber during the intake stroke and reduce the intake air temperature, thereby reliably preventing the occurrence of knocking.

  When the pressure sensor for the chamber is provided and the control means controls the opening / closing operation of the second on-off valve and the air release valve based on the detection information from the pressure sensor for the chamber and the intake pressure sensor, the inside of the decompression tank is efficiently decompressed. Can be made.

  When the pressure in the intake passage is higher than the pressure in the chamber, the control means opens and closes the second on-off valve to generate a vibrating pressure wave in the second branch passage between the intake passage and the chamber. Thus, the pressure in the vacuum tank can be reliably reduced.

  When the pressure in the chamber is higher than a preset pressure, for example, atmospheric pressure, the control means can quickly reduce the pressure in the chamber to atmospheric pressure by opening and closing the atmosphere release valve.

  When the decompression means has an air release valve that can open the inside of the decompression tank to the atmosphere, and the control device controls the opening / closing operation of the atmosphere release valve based on the detection information from the pressure sensor for the decompression tank, Can be quickly reduced to atmospheric pressure.

  An embodiment in which an intake air control apparatus for an internal combustion engine according to the present invention is applied to a spark ignition internal combustion engine in which a turbocharger is incorporated will be described in detail with reference to FIGS. However, the present invention is not limited to such an embodiment, and is applied to a combination of all types of superchargers and internal combustion engines, such as a compression ignition internal combustion engine in which a mechanical supercharger is incorporated. Note that you can.

  The engine system in the present embodiment is schematically shown in FIG. 1, and its control block is shown in FIG. The engine 10 according to this embodiment is of a spark ignition type in which fuel such as gasoline, alcohol, a mixture thereof, or liquefied natural gas is directly injected into the combustion chamber 12 from the fuel injection valve 11 and ignited by the spark plug 13. .

  A valve operating mechanism including an intake valve 17 that opens and closes the intake port 14 and an exhaust valve 18 that opens and closes the exhaust port 15 is incorporated in the cylinder head 16 in which the intake port 14 and the exhaust port 15 facing the combustion chamber 12 are formed. ing. An ignition plug 13 for igniting the fuel injection valve 11 and the air-fuel mixture in the combustion chamber 12 and an ignition coil 19 for generating a spark in the ignition plug 13 are also incorporated in the cylinder head 16. The fuel injection valve 11 in this embodiment employs a direct injection type that injects fuel directly into the combustion chamber 12, but a port injection type that injects into the intake port 14 can also be adopted. It is.

  The turbocharger 20 for increasing the charging efficiency of the intake air supercharges the combustion chamber 12 using the kinetic energy of the exhaust gas flowing in the exhaust passage 21. The turbocharger 20 is integrated with the compressor 22 and the compressor 22. The main part is composed of a turbine 23 that rotates in a straight line. The compressor 22 is incorporated in the middle of an intake pipe 26 positioned downstream of a surge tank 25 formed in the middle of an intake passage 24 communicating with the intake port 14. The turbine 23 is connected to the cylinder head 16 so as to communicate with the exhaust port 15 and is incorporated in an exhaust pipe 27 defining the exhaust passage 21 together with the exhaust port 15. Note that in order to reduce the intake air temperature heated by the compressor 22 that generates heat due to heat transfer from the turbine 23 side that becomes high temperature due to the exhaust, heat exchange is performed in the middle of the intake passage 24 between the compressor 22 and the surge tank 25. A vessel (intercooler) 28 is incorporated.

In the middle of the intake pipe 26 between the previous surge tank 25 and the previous heat exchanger 28, the intake passage 24 is opened via the throttle actuator 30 based on the depression amount of the accelerator pedal 29 operated by the driver. A throttle valve 31 for adjusting the degree is incorporated. Therefore, an accelerator opening sensor 32 for detecting the amount of depression is attached to the accelerator pedal 29, the detection information are outputted to the ECU (E lectronic C ontrol U nit ) 33. As described above, in this embodiment, the depression operation of the accelerator pedal 29 and the opening / closing operation of the throttle valve 31 are mechanically separated so that the opening / closing operation of the throttle valve 31 can be electrically controlled using the throttle actuator 30. Yes. However, the accelerator pedal 29 and the throttle valve 31 may be mechanically connected. In this case, the throttle actuator 30 can be omitted.

  In the middle of the intake passage 24 upstream of the compressor 22 of the turbocharger 20, an air flow meter 34 that detects the intake flow rate flowing in the intake passage 24 and outputs this to the ECU 33 is attached. An intake pressure sensor 35 that detects the pressure in the intake passage 24 and outputs it to the ECU 33 is provided in the intake pipe 26 between the throttle valve 31 and the heat exchanger 28 for the turbocharger 20. It is attached.

  A crank angle sensor 40 that detects the rotational phase of the crankshaft 39 to which the piston 36 is connected via the connecting rod 38, that is, the crank angle, and outputs the detected crank angle to the ECU 33 is attached to the cylinder block 37 in which the piston 36 reciprocates. It has been.

  A catalyst device (not shown) for detoxifying harmful substances generated by combustion of the air-fuel mixture in the combustion chamber 12 is incorporated in the exhaust passage 21 downstream of the turbine 23 of the turbocharger 20. It is.

  One end of the branch pipe 42 defining the branch passage 41 is connected to the middle of the intake pipe 26 between the intake port 14 and the surge tank 25 described above, and the other end of the branch pipe 42 has a sealing property. A decompression tank 43 is connected. The decompression tank 43 incorporates a decompression tank pressure sensor 44 that detects the internal pressure and outputs the detected pressure to the ECU 33. Further, in the middle of the branch passage 41, a first on-off valve 45 capable of communicating or blocking between the intake passage 24 and the decompression tank 43 by opening and closing the branch passage 41 and the command from the ECU 33. And a valve actuator 46 for opening and closing the motor. In the present embodiment, the pressure in the decompression tank 43 is detected using the pressure sensor 44 for the decompression tank, but the opening of the throttle valve 31, the intake pressure detected by the intake pressure sensor 35, and the first It is also possible to estimate this based on the operation history of the on-off valve 45. Further, it is possible to estimate the pressure in the intake passage 24 based on the opening of the throttle valve 31, and in this case, the intake pressure sensor 35 can be omitted.

  The first on-off valve 45 is determined in advance so that a negative pressure wave, which is a minimum portion of the intake pressure that pulsates as the valve is opened, reaches the combustion chamber 12 during the opening period of the intake valve 17. Under the conditions, it is possible to open and close at least once in conjunction with the opening and closing operation of the intake valve 17 during one combustion cycle. For this reason, the first opening / closing valve 45 and the valve actuator 46 need to have extremely high control responsiveness capable of an accurate opening / closing operation according to the opening timing of the intake valve 17. In the present embodiment, the first opening / closing valve 45 is set to open and close during the opening period of the intake valve 17, but the opening timing of the first opening / closing valve 45 is set to the opening timing of the intake valve 17. It is possible to set as soon as possible. Further, the closing timing of the first on-off valve 45 may be set later than the closing timing of the intake valve 17. In any case, of the intake air that has become high pressure due to supercharging during the opening period of the intake valve 17, the negative pressure wave that becomes the minimum part of the intake pressure that pulsates with the opening of the first on-off valve 45. All or at least a part acts on the combustion chamber 12, and the pressure can be reduced. Further, in the present embodiment, the first on-off valve 45 is opened and closed once each in one combustion cycle, but can be opened and closed twice or more.

  In the middle of the intake pipe 26 upstream of the communicating portion with the branch passage 41 (in the present embodiment, in the middle of the intake pipe 26 between the throttle valve 31 and the intake pressure sensor 35), the second branch passage 47 is provided. One end of a second branch pipe 48 to be defined is connected, and a chamber 49 having a sealing property is defined at the other end of the second branch pipe 48. Further, a chamber pressure sensor 50 that detects the pressure in the chamber 49 and outputs the pressure to the ECU 33, and an atmosphere release valve 51 that can open the chamber 49 to the atmosphere based on a command from the ECU 33 are provided. . In the present embodiment, a non-energized closed type solenoid valve is employed as the atmosphere release valve 51, but any type of valve may be employed as long as it has a highly airtight structure capable of opening and closing the chamber 49. can do. In the middle of the second branch pipe 48, based on a command from the ECU 33, a second on-off valve 52 capable of communicating or blocking between the intake passage 24 and the chamber 49 by opening and closing the second branch passage 47. A valve actuator 53 for opening and closing the lever is attached. Further, one end of the communication pipe 54 is connected to the middle of the second branch pipe 48 between the chamber 49 and the second on-off valve 52, and the other end is connected to the decompression tank 43. The communication pipe 54 defines a communication path 55 that connects the inside of the decompression tank 43 and the second branch path 47. A check valve 56 that allows gas flow only from the decompression tank 43 side to the second branch passage 47 side is incorporated in the middle of the communication pipe 54. Due to the presence of the check valve 56, when the pressure on the second branch passage 47 side is lower than the pressure in the decompression tank 43, the communication passage 55 is opened and the pressure in the decompression tank 43 can be lowered. It is like that. The check valve 56 in the present embodiment uses a ball 57 as a valve body and a spring 58 that biases the ball 57 so that the communication passage 55 is closed. However, any type can be adopted as long as there is no possibility that the communication path 55 is opened by vibration or inertial force.

  When the pressure in the chamber 49 is lower than the pressure in the intake passage 24, the second branch pipe 48 instantaneously opens and closes the second on-off valve 52 to open the second on-off valve 52 and the chamber 49. For generating a pressure wave that oscillates in the second branch passage 47 between them. The pressure wave reciprocates in the second branch passage 47 while the positive pressure and the negative pressure are alternately attenuated, so that when the negative pressure larger than the pressure reducing tank 43 passes through one end side of the communication passage 55, The stop valve 56 can be opened to reduce the pressure in the decompression tank 43. Accordingly, the second on-off valve 52 and its valve actuator 53 must also have a very high control response, similar to the first on-off valve 45 and its valve actuator 46.

  The above-described second branch passage 47, chamber 49, second on-off valve 52, communication passage 55, check valve 56, and the like function as decompression means in the present invention.

  The opening / closing cycle of the second opening / closing valve 52 is preferably set according to the attenuation cycle of the pressure wave generated in the second branch passage 47, and can be theoretically predicted from the design conditions. It is also effective to obtain by experiment. Further, by repeatedly opening and closing the second on-off valve 52, the pressure in the chamber 49 gradually increases, and there is no difference between the pressure in the intake passage 24 and the pressure in the chamber 49, and the pressure in the pressure reducing tank 43 is reduced. It becomes difficult. However, in the present embodiment, in such a case, the pressure in the chamber 49 is made lower than the pressure in the intake passage 24 by opening the air release valve 51 and lowering the pressure in the chamber 49 to atmospheric pressure. It becomes possible. That is, when the intake pressure in the intake passage 24 is higher than the atmospheric pressure, even if the pressure in the chamber 49 is atmospheric pressure, the second on-off valve 52 is driven to open and close to reduce the pressure in the decompression tank 43. It is possible to make it.

  The ECU 33 is a well-known one-chip microprocessor, and includes a CPU, ROM, RAM, non-volatile memory, input / output interface and the like interconnected by a data bus (not shown). Based on the detection information from the sensors 32, 35, 40, 44, 50 and the air flow meter 34 described above, the ECU 33 performs the fuel injection valve 11, so that the engine 10 can be smoothly operated according to a preset program. The operation of the ignition coil 19, the throttle actuator 30, the valve actuators 46 and 53, the air release valve 51, and the like is controlled. Further, the fuel injection amount from the fuel injection valve 11 is set to be a predetermined ratio with respect to the load of the engine 10 calculated based on the detection values of the accelerator opening sensor 32 and the air flow meter 34.

  The ROM of the ECU 33 stores a valve opening timing map (not shown) in which a parameter indicating the driving state of the vehicle and the valve opening timing and valve closing timing of the first on-off valve 45 are stored in association with each other. The ECU 33 controls the opening / closing operation of the first opening / closing valve 45 based on the valve opening timing map. In this embodiment, the engine speed detected by the crank angle sensor 40 and the load of the engine 10 are used as parameters indicating the driving state of the vehicle. The engine speed is calculated in the ECU 33 based on the detection signal from the crank angle sensor 40, and the load of the engine 10 is calculated as the intake air amount per cylinder from the intake air amount detected by the air flow meter 25. It is calculated in the ECU 33.

  The ROM of the ECU 33 also stores an ignition timing map in which parameters indicating the driving state of the vehicle and the ignition timing of the spark plug 13 are stored in association with each other. Based on this ignition timing map, the ECU 33 ignites the spark plug 13 at a set timing via the ignition coil 19. In this embodiment, the pressure in the decompression tank 43, the engine speed, and the load of the engine 10 are used as parameters indicating the operating state.

FIG. 2 shows a control procedure of the first on-off valve 45 in the embodiment. That is, it is determined in step S11 whether or not the engine 10 is in the low load region. Engine 10 is in a low load region, i.e. a turbo when the supercharger 20 is determined to be non in non supercharger operating state function, the pressure P _D intake passage in shifts vacuum tank 43 in step S12 pressure 24 (hereinafter, the intake pressure and describes) whether higher is determined than P _I. Here, the pressure P _D in the vacuum tank 43 is higher than the intake air pressure P _I, i.e. by the intake negative pressure in the intake passage 24, the pressure P _D in the vacuum tank 43 when it is determined that there is room for depressurizing Moves to step S13 and opens the first on-off valve 45. Then, it is determined whether the pressure P _D in the vacuum tank 43 is less than the intake air pressure P _I at step S14. The pressure P _D in the vacuum tank 43 at this step S14 is less than or equal to the intake pressure P _I, i.e. be previously held the first on-off valve 45 in the open state, thereby reducing the pressure in the vacuum tank 43 If it is determined that the operation cannot be performed, the process proceeds to step S15 and the first on-off valve 45 is closed. Thereafter, the process proceeds to step S16, and it is determined whether or not the engine 10 is in a knocking occurrence region where the turbocharger 20 operates. Here, when the engine 10 is determined to be in the knocking region determines whether higher than the pressure P _D in the vacuum tank 43 is the intake pressure P _I proceeds to step S17. Then, the pressure P _D in the vacuum tank 43 is higher than the intake air pressure P _I, i.e., when it is determined that open the first on-off valve 45 it is possible to reduce the pressure in the combustion chamber 12 , The process proceeds to step S18. In step S18, the first on-off valve 45 is opened / closed during the intake stroke, and a part of the intake air flowing through the intake passage 24 is guided into the decompression tank 43, thereby reducing the pressure in the combustion chamber 12. Let As a result, the intake air temperature in the combustion chamber 12 decreases, and knocking is less likely to occur.

  On the other hand, if it is determined in step S11 that the engine 10 is not in a low load region where the turbocharger 20 does not operate, the decompression in the decompression tank 43 due to the opening operation of the first on-off valve 45 is not performed. Since this is possible, the first on-off valve 45 is driven to close in step S15. This is for ending the valve opening drive of the first on-off valve 45 in the step of S13 even when the first on-off valve 45 is in the closed state, and thereafter, the process proceeds to the step of S16. .

The pressure P _D in the vacuum tank 43 at step S12 is in the case of equal to or less than the intake air pressure P _I, because the engine 10 is in the low load region, nothing returns to step S11 without. On the other hand, if it is determined in step S16 that the engine 10 is not in the knocking occurrence region, there is no need to open / close the first on-off valve 45, and the process returns to step S11 without doing anything. Similarly, if the intake air pressure P _I in step S17 is determined to be less than the pressure P _D in the vacuum tank 43, also by opening and closing the first on-off valve 45 to suppress the occurrence of knocking Therefore, the process returns to step S11 without doing anything.

When the pressure P _D in the vacuum tank 43 at step S14 is determined to be higher than the intake air pressure P _I further pressure of the first on-off valve 45 vacuum tank 43 and held in the open state Since it can be reduced, the process returns to step S11 without doing anything.

  As described above, when the pressure in the decompression tank 43 is higher than the intake negative pressure in the operation state in which the intake negative pressure is generated in the intake passage 24, the first on-off valve 45 is opened and the decompression tank is opened. The inside of 43 can be depressurized. Further, when the vehicle is in a knocking occurrence region and the pressure in the decompression tank 43 is lower than the intake pressure, the first on-off valve 45 is driven to open and close during the intake stroke to reduce the intake pressure in the combustion chamber 12, Along with this, the intake air temperature is lowered. Thereby, it is possible to suppress the occurrence of knocking.

When is repeated a first S18 in the step of opening and closing the on-off valve 45 during the intake stroke, intake air pressure P _I pressure in the vacuum tank 43 gradually rises and falls below the pressure P _D in the vacuum tank 43 End up. That is, there is a possibility that the intake pressure in the combustion chamber 12 cannot be reduced even if the first on-off valve 45 is opened. In the present invention, the above-described pressure reducing means is incorporated so that such a problem does not occur, and it is possible to continue the control for suppressing the occurrence of knocking even when the engine 10 is continuously in the knocking occurrence region. It is.

FIG. 3 shows a control procedure of the second opening / closing valve 52 and the atmosphere opening valve 51 of the decompression means in the present embodiment. That is, when the pressure P _C in the chamber 49 is determined to be lower than the intake air pressure P _I in S21 in step determines whether or not the flag is set the procedure proceeds to S22 steps. At first, since the flag is not set, the process proceeds to step S23, and the second on-off valve 52 is opened / closed. Then, a flag is set in step S24, and the count value C of the counter is set to 1 in step S25. Then, the process proceeds to step S26 and the pressure P _C in the chamber 49 is set to a preset threshold value P _R. Or higher is determined.

  By the opening / closing drive of the second opening / closing valve 52 in the step of S23, a pressure wave that vibrates in the second branch passage 47 located between the chamber 49 and the second opening / closing valve 52 is generated. When the negative pressure wave generated thereby is lower than the pressure in the decompression tank 43, the check valve 56 is opened and the decompression in the decompression tank 43 is performed via the communication path 55.

The opening and closing of the second on-off valve 52 at S23 in step, although the pressure in the chamber 49 rises, when the pressure P _C in the chamber 49 is equal to or less than still threshold P _R at step S26 Shifts to step S27. Then, whether the count value C of the counter is smaller than the count end value C _R is determined. Initially, the count value C is smaller than the count end value C _R, returns to this state the first S21 in step.

On the other hand, the threshold value P _R pressure P _C in the chamber 49 at S21 in step if it is determined that the intake pressure P _I above, the pressure P _C in the chamber 49 proceeds to step S26 has been set in advance Or higher is determined. If it is determined in step S26 that the pressure P _C in the chamber 49 is higher than the threshold value P _R , the chamber 49 and the second on-off valve can be operated even if the second on-off valve 52 is opened / closed. A pressure wave having a large amplitude cannot be generated in the second branch passage 47 between the two. Accordingly, in this case, the process proceeds to step S28, and the atmosphere release valve 51 provided in the chamber 49 is driven to open for a predetermined time, thereby reducing the pressure in the chamber 49 to atmospheric pressure. That is, the threshold value P _R is set to a pressure that is the same as or slightly higher than the atmospheric pressure. This case, since the intake air pressure P _I in the knocking region where the supercharging operation is performed becomes higher pressure than atmospheric pressure, reduced pressure in the vacuum tank 43 and the second opening and closing valve 52 during the supercharging operation opening and closing to Can be done. That is, as described above, during the non-supercharging operation in which the intake passage 24 has a negative pressure, the decompression tank 43 is decompressed by opening the first on-off valve 45, and the second on-off valve 52 is opened / closed during the supercharging operation. The inside of the decompression tank 43 can be decompressed by driving. As a result, even when the supercharging operation continues for a long time, the inside of the decompression tank 43 is kept in a decompressed state, and the first opening / closing is performed during the intake stroke in order to suppress the occurrence of knocking. The valve 45 can be continuously opened and closed.

After the atmospheric release valve 51 is driven to open for a predetermined time in the previous step S28, the process proceeds to the step S29 to reset the flag, that is, the counter count value C is reset to 0, and the process returns to the step S21. Further, the count value C of the counter reaches the count end value C _R in the step S27, that is, the opening / closing drive of the second on-off valve 52 in the step S23 is performed between the chamber 49 and the first on-off valve 45. Even when it is determined that the vibration of the pressure wave generated in the second branch passage 47 is sufficiently attenuated, the process proceeds to step S29 and the flag is reset.

  If it is determined that the flag is set in step S22, that is, if the pressure wave is oscillating while being attenuated in the second branch passage 47, the process proceeds to step S30 and the counter After incrementing the count value C by one, the process proceeds to step S26.

Thus, if the pressure in the chamber 49 is lower than that of the intake air pressure P _I, by performing every predetermined time to fit the opening and closing driving of the second on-off valve 52 in the damping period of the pressure wave, the inside of the decompression tank 43 It can be kept under reduced pressure. That is, the opening / closing drive of the first opening / closing valve 45 during the intake stroke can be continuously performed.

In the case of performing the opening and closing of the first on-off valve 45 during the intake stroke, ECU 33, based on the pressure P _D in the vacuum tank 43, the engine speed, the intake air amount per cylinder, the ignition timing Calculate the ignition timing from the map. More specifically, as the pressure P _D in the vacuum tank 43 is low, the amount of air fed to the combustion chamber 12 is decreased, because the pressure in the combustion chamber 12 in the compression stroke is lowered, taking this into account As a result, the amount of advancement of the ignition timing tends to increase.

As the decompression means of the present invention, a decompression means that is simpler than that of the previous embodiment can be employed. Such an engine system according to another embodiment of the present invention is schematically shown in FIG. 4, but the members having the same functions as those of the previous embodiment are indicated by the same reference numerals, and overlapping descriptions are omitted. Shall be omitted. That is, the second branch passage 47, the chamber 49, the second on-off valve 52, the communication passage 55, the check valve 56, and the like described above are omitted, and in this embodiment, the air release valve 59 is used as a decompression unit to reduce the pressure. It is incorporated in the tank 43. The air release valve 59 is an electromagnetic valve deenergized during obstructive, if a vacuum tank 43 exceeds a predetermined pressure P _R set in advance for a higher pressure than the atmospheric pressure, it opens the air release valve 59 Thus, the inside of the decompression tank 43 is lowered to the atmospheric pressure.

FIG. 5 shows a control procedure of the first on-off valve 45 and the atmosphere release valve 59 in such an embodiment. That is, it is determined in step S31 whether or not the engine 10 is in the low load region. Engine 10 is in a low load region, i.e. a turbo when the supercharger 20 is determined to be in the operating state of not functioning, the pressure P _D is the intake air pressure P in the transition to a reduced pressure tank 43 in step S32 _It is determined whether it is higher than _I. Here, the pressure P _D in the vacuum tank 43 is higher than the intake air pressure P _I, i.e. by the intake negative pressure in the intake passage 24, the pressure P _D in the vacuum tank 43 when it is determined that there is room for depressurizing Moves to step S33 and opens the first on-off valve 45. Then, it is determined whether the pressure P _D in the vacuum tank 43 is less than the intake air pressure P _I in S34 in step. The pressure P _D in the vacuum tank 43 at this S34 in step is less than the intake air pressure P _I, i.e. be previously held the first on-off valve 45 in the open state, thereby reducing the pressure in the vacuum tank 43 If it is determined that the operation cannot be performed, the process proceeds to step S35 and the first on-off valve 45 is closed. Thereafter, the process proceeds to step S36 to determine whether or not the engine 10 is in the knocking occurrence region. Here, when the engine 10 is determined to be in the knocking region determines whether the pressure P _D in the vacuum tank 43 is less than atmospheric pressure P _A proceeds to step S37. Then, when the pressure P _D in the vacuum tank 43 is equal to or less than the atmospheric pressure P _A is either the pressure P _D in the vacuum tank 43 proceeds to S38 in step is lower than the intake air pressure P _I not Determine whether. Then, the pressure P _D in the vacuum tank 43 is lower than the intake air pressure P _I, i.e., it is possible to reduce the intake pressure of the first on-off valve 45 the combustion chamber 12 by opening and closing the during the intake stroke If it is determined, the process proceeds to step S39. In step 39, the first on-off valve 45 is opened / closed during the intake stroke, and a part of the intake air flowing through the intake passage 24 is guided into the decompression tank 43, whereby the intake pressure flowing into the combustion chamber 12 is reached. Decrease. As a result, the intake air temperature in the combustion chamber 12 decreases, and knocking is less likely to occur.

  On the other hand, if it is determined in step S31 that the engine 10 is not in the low load region, it is impossible to depressurize the decompression tank 43 by opening the first on-off valve 45. After the first on-off valve 45 is driven to close, the process proceeds to step S36. This is for ending the valve opening drive of the first on-off valve 45 in step S33 even if the first on-off valve 45 is in the closed state.

The pressure P _D in the vacuum tank 43 at step S32 is in the case of equal to or less than the intake air pressure P _I, because the engine 10 is in the low load region, nothing returns to S31 step without. Further, when the pressure P _D in the vacuum tank 43 is determined to be higher than the intake air pressure P _I in S34 in step, the pressure of the first on-off valve 45 a vacuum tank 43 and held in the open state Can be further reduced, so the process returns to step S11 without doing anything. Furthermore, even if it is determined in step S36 that the engine 10 is not in the knocking occurrence region, there is no need to drive the first on-off valve 45, so the process returns to step S11 without doing anything.

When the pressure P _D of the pressure reducing tank 43 at step S37 is determined to be higher than the atmospheric pressure P _A is migrated by opening and closing the atmosphere opening valve 59 to step S40, the pressure in the vacuum tank 43 lower the P _D to the atmospheric pressure P _a. By thus reducing the pressure P _D of the air release valve 59 opening and closing to the vacuum tank 43 to the atmospheric pressure P _A, if the intake air pressure P _I is the atmospheric pressure P _A above, the during the intake stroke 1 The on-off valve 45 can be opened and closed to reduce the pressure in the combustion chamber 12.

In the case where the pressure P _D in the vacuum tank 43 at S38 in step is determined to be the intake air pressure P _I above, reducing the pressure in the combustion chamber 12 even if opening and closing the first on-off valve 45 Therefore, nothing is done and the process returns to step S31.

  It should be noted that the present invention should be construed only from the matters described in the claims, and in the above-described embodiment, all the changes and modifications included in the concept of the present invention are other than those described. Is possible. That is, all matters in the above-described embodiment are not intended to limit the present invention, and include any configuration not directly related to the present invention. To get.

1 is a conceptual diagram of an embodiment in which the present invention is applied to a spark ignition internal combustion engine in which a turbocharger is incorporated. It is a flowchart showing the control procedure of the 1st on-off valve in embodiment shown in FIG. It is a flowchart showing the control procedure of a pressure reduction means. It is a conceptual diagram of other one Embodiment of this invention. It is a flowchart showing the control procedure of the 1st on-off valve in embodiment shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Engine 11 Fuel injection valve 12 Combustion chamber 13 Spark plug 14 Intake port 15 Exhaust port 16 Cylinder head 17 Intake valve 18 Exhaust valve 19 Ignition coil 20 Turbocharger 21 Exhaust passage 22 Compressor 23 Turbine 24 Intake passage 25 Surge tank 26 Intake Pipe 27 Exhaust pipe 28 Heat exchanger (intercooler)
29 Accelerator pedal 30 Throttle actuator 31 Throttle valve 32 Accelerator opening sensor 33 ECU
34 Air flow meter 35 Intake pressure sensor 36 Piston 37 Cylinder block 38 Connecting rod 39 Crank shaft 40 Crank angle sensor 41 Branch passage 42 Branch pipe 43 Pressure reducing tank 44 Pressure reducing tank pressure sensor 45 First on-off valve 46 Valve actuator 47 Second actuator Branch passage 48 Second branch pipe 49 Chamber 50 Pressure sensor for chamber 51 Air release valve 52 Second on-off valve 53 Valve actuator 54 Communication pipe 55 Communication passage 56 Check valve 57 Ball 58 Spring 59 Air release valve

Claims (8)

An intake control device for an internal combustion engine in which a supercharger is incorporated,
A branch passage whose one end communicates with an intake passage downstream of the compressor of the supercharger;
A decompression tank communicating with the other end of the branch passage;
An on-off valve for opening and closing the branch passage;
Control means for controlling the opening / closing operation of the opening / closing valve in conjunction with the opening / closing operation of the intake valve;
An intake air control apparatus for an internal combustion engine, comprising: a pressure reducing means for keeping the inside of the pressure reducing tank at a lower pressure than the pressure of the intake air flowing in the intake passage separately from the on-off valve. An intake pressure sensor for detecting the pressure in the intake passage;
A pressure reducing tank pressure sensor for detecting the pressure in the pressure reducing tank; and the control means opens and closes the on-off valve based on detection information from the intake pressure sensor and the pressure reducing tank pressure sensor. The intake control device for an internal combustion engine according to claim 1. The decompression means includes a second branch passage whose one end communicates with the intake passage on the upstream side of the communication portion with the branch passage;
A chamber communicating with the other end of the second branch passage;
A second on-off valve for opening and closing the second branch passage;
A communication passage communicating the second branch passage between the second on-off valve and the chamber and the decompression tank;
A check valve that is provided in the communication passage and allows gas flow only from the decompression tank side to the second branch passage;
The intake control device for an internal combustion engine according to claim 2, further comprising an atmosphere release valve capable of opening the inside of the chamber to the atmosphere.   The chamber further includes a chamber pressure sensor for detecting the pressure in the chamber, and the control means is configured to detect the second on-off valve and the air release based on detection information from the chamber pressure sensor and the intake pressure sensor. 4. The intake control apparatus for an internal combustion engine according to claim 3, wherein the valve opening / closing operation is controlled.   5. The intake control apparatus for an internal combustion engine according to claim 4, wherein the control means opens and closes the second on-off valve when the pressure in the intake passage is higher than the pressure in the chamber.   5. The intake control device for an internal combustion engine according to claim 4, wherein the control means opens and closes the atmosphere release valve when the pressure in the chamber is higher than a preset pressure.   The decompression means includes an atmosphere release valve that can open the inside of the decompression tank to the atmosphere, and the control device controls an opening / closing operation of the atmosphere release valve based on detection information from the pressure sensor for the decompression tank. The intake control device for an internal combustion engine according to claim 2.   The intake control device for an internal combustion engine according to claim 7, wherein the control means opens and closes the atmosphere release valve when the pressure in the decompression tank is higher than a preset pressure.

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