JP2017198118A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine that enables actual torque to follow rapid change of required torque and can secure stable combustion.SOLUTION: A control device for an internal combustion engine includes: a supercharger 9 for compressing intake air; an injector 10 for injecting fuel; an intake valve 11 opened/closed to communicate/block an intake passage 16a and a combustion chamber 7 with/from each other; an exhaust valve 21 opened/closed to communicate/block an exhaust passage 23a and the combustion chamber 7 with/from each other; and an ECU 3 for calculating a target air-fuel mixture mass that attains target SLOW torque, controlling boost pressure of the supercharger 9 so as to reach the target air-fuel mixture mass, controlling fuel injection amount so as to reach target FAST torque, calculating a residual gas target mass on the basis of target fuel amount that attains the target FAST torque and controlling the intake valve 11 and the exhaust valve 21 so as to reach the residual gas target mass.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an internal combustion engine.

  Conventionally, as a combustion mode of an internal combustion engine such as a gasoline engine, SI (Spark Ignition) combustion in which an air-fuel mixture is forcibly ignited by spark discharge from a spark plug has been widely used. Development of a gasoline engine that uses premixed compression self-ignition combustion, which introduces the burned gas and self-ignites the air-fuel mixture, as a combustion mode is underway. Here, the premixed compression self-ignition combustion is referred to as HCCI (Homogeneous Charge Compression Ignition) combustion.

  In an internal combustion engine equipped with this HCCI combustion function, the exhaust valve closing timing (EVC) is advanced by a variable valve mechanism so that a part of the burned gas remains in the cylinder, and is renewed in the next intake stroke. There is a negative valve overlap (NVO) system that raises the temperature of the air-fuel mixture mixed with the air.

  In Patent Document 1, a target cam phase is calculated such that a pre-compression ignition temperature is obtained from the required torque, and the compression end temperature at the next phase estimated from the phase difference between the target cam phase and the current cam phase is the compression ignition temperature. Is calculated, and the amount of fuel injection is controlled in accordance with the corrected required torque to suppress knocking and misfire and ensure stable combustion.

  Patent Document 2 describes that, in an internal combustion engine equipped with a supercharger, a target supercharging pressure is set based on a required torque, a combustion chamber temperature, and a required rotational speed, and control is performed so as to achieve this target supercharging pressure. ing.

JP 2011-220121 A JP 2004-285997 A

  However, in such a control device for an internal combustion engine, since the next phase and the supercharging pressure are calculated from the required torque, when the required torque changes suddenly, the intake / exhaust valve has a slower response than the fuel amount. Because the residual gas temperature and exhaust pressure are different from the steady state, the temperature and the in-cylinder gas amount (excluding fuel) during compression are set to G, and the fuel amount is set to F. The state in the combustion chamber such as G / F (weight ratio) at the time may deviate from the steady state, and misfires, torque fluctuations may occur, and noise and NOx emissions may increase.

  As a countermeasure, it is conceivable to calculate the fuel injection amount in accordance with the phase of the intake / exhaust valve with slow response and the change in supercharging pressure, but unless the change is very slow, the state in the combustion chamber is steady. When the required torque from the driver, the transmission, the skid prevention device or the like changes suddenly, the actual torque cannot follow, resulting in problems such as shock, rotational blow-up, and skidding.

  Accordingly, the present invention provides an internal combustion engine control apparatus that can cause the actual torque to follow a sudden change in the required torque, ensure stable combustion, and operate the internal combustion engine under conditions where the thermal efficiency is as high as possible. It is an object.

  In order to solve the above problems, the present invention is a control device for an internal combustion engine that performs premixed compression auto-ignition combustion, and when it is necessary to increase the torque with a high response, the target torque is increased. And a control unit for controlling the mass of the air-fuel mixture and controlling the fuel injection amount so as to obtain the current target torque.

  As described above, according to the present invention, there is provided a control device for an internal combustion engine that can cause the actual torque to follow a sudden change in the required torque, ensure stable combustion, and operate the internal combustion engine under conditions where the thermal efficiency is as high as possible. Can be provided.

FIG. 1 is a schematic configuration diagram of a control device for an internal combustion engine according to an embodiment of the present invention. FIG. 2 is an input / output diagram of a target torque calculation unit of the control device for the internal combustion engine according to the embodiment of the present invention. FIG. 3 is a block diagram of a block for controlling the supercharger of the control device for the internal combustion engine according to the embodiment of the present invention. FIG. 4 is a block diagram of a block for controlling the fuel injection amount of the control device for the internal combustion engine according to the embodiment of the present invention. FIG. 5 is a block diagram of a block for controlling the intake valve and the exhaust valve of the control device for an internal combustion engine according to the embodiment of the present invention.

  Hereinafter, an internal combustion engine control apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

  In FIG. 1, a vehicle 1 equipped with an internal combustion engine control apparatus according to an embodiment of the present invention includes an internal combustion engine type engine 2 and an ECU (Electronic Control Unit) 3 as a control unit. .

  The engine 2 includes a cylinder block 4 and a cylinder head 5 fastened to the upper part of the cylinder block 4. The cylinder block 4 is formed with a cylinder 4a, and a piston 6 that can reciprocate up and down is accommodated inside the cylinder (hereinafter referred to as "in-cylinder").

  A combustion chamber 7 is provided in the upper part of the cylinder 4a. The combustion chamber 7 is defined by the top surface of the piston 6 and the lower surface of the cylinder head 5. The engine 2 is a so-called four-cycle gasoline engine that performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while the piston 6 reciprocates twice in a cylinder.

  The piston 6 is connected to a crankshaft (not shown) via a connecting rod 8. The connecting rod 8 converts the reciprocating motion of the piston 6 into the rotational motion of the crankshaft.

  The cylinder head 5 is provided with a spark plug 50, an intake port 51, and an exhaust port 52. The spark plug 50 is disposed in the cylinder head 5 with an electrode protruding into the combustion chamber 7, and its ignition timing is adjusted by the ECU 3.

  The intake port 51 communicates the combustion chamber 7 with an intake passage 16a described later. The intake port 51 is provided with an intake valve 11.

  The intake valve 11 is opened and closed so as to communicate or block the intake passage 16a and the combustion chamber 7. The intake valve 11 is opened and closed by an intake side variable valve mechanism 12.

  As the intake side variable valve mechanism 12, for example, an electromagnetic variable valve mechanism that opens and closes the intake valve 11 by an electromagnetic actuator composed of an electromagnet and a spring can be used. Specifically, the intake side variable valve mechanism 12 opens the intake valve 11 that is normally urged in the valve closing direction by a spring by attracting a movable portion fixed to the intake valve 11 by excitation of an electromagnet. It is designed to move in the valve direction.

  Further, the intake side variable valve mechanism 12 is electrically connected to an ECU 3 to be described later, and excitation and de-excitation of the electromagnet are controlled by the ECU 3. Therefore, the ECU 3 can arbitrarily change the opening / closing timing of the intake valve 11, thereby easily adjusting the opening period of the intake valve 11.

  The intake side variable valve mechanism 12 may be a hydraulic variable valve mechanism using a hydraulic actuator instead of an electromagnetic actuator. Further, as the intake-side variable valve mechanism 12, a mechanical variable valve mechanism that can change the opening / closing timing of the intake valve 11 using cam members such as a main cam and a sub cam may be used.

  Further, the intake side variable valve mechanism 12 is configured such that the lift amount of the intake valve 11 can be continuously changed with the opening / closing timing of the intake valve 11 by adjusting the excitation current to the electromagnet, for example, by the ECU 3. It may be.

  An intake manifold 13 is connected to the cylinder head 5 on the intake port 51 side. An injector 10 is provided in the vicinity of the intake port 51 of the intake manifold 13.

  The injector 10 is a so-called port injection type fuel injection valve that injects fuel pumped by a fuel pump from a fuel tank (not shown) into the intake port 51. The injector 10 is not limited to the port injection type, and may be a so-called direct injection type fuel injection valve that directly injects fuel into the combustion chamber 7.

  The fuel injected into the intake port 51 is mixed with intake air, that is, fresh air, to be mixed into the combustion chamber 7. The air-fuel mixture introduced into the combustion chamber 7 burns and explodes due to spark discharge by the spark plug 50 or self-ignition due to compression in the combustion chamber. Due to the combustion and explosion of the air-fuel mixture, the piston 6 reciprocates in the cylinder 4a, and the crankshaft rotates.

  A surge tank 14 is provided upstream of the intake manifold 13 in the intake direction where intake air flows. The surge tank 14 is provided with an intake pressure sensor 15 for detecting intake pressure.

  An intake pipe 16 is connected to the upstream side of the surge tank 14 in the intake direction. An intake passage 16 a communicating with the intake port 51 is formed inside the intake pipe 16. In the intake passage 16a, a compressor 17 that compresses air, an intercooler 18 that cools the compressed air, and a throttle valve 19 that adjusts the flow rate of the air are provided in order from the upstream in the intake direction.

  The throttle valve 19 adjusts the intake air amount of the engine 2 by controlling the throttle opening degree according to a command signal from the ECU 3. The throttle valve 19 is provided with a throttle opening sensor 41 for detecting the throttle opening.

  On the upstream side of the throttle valve 19 in the intake direction, a supercharging pressure sensor 42 that detects a supercharging pressure by a supercharger 9 described later, and an intake air temperature sensor 43 that detects the intake air temperature upstream of the throttle valve 19 in the intake direction, Is provided.

  On the other hand, the exhaust port 52 is provided with the exhaust valve 21. The exhaust valve 21 is opened and closed so as to communicate or block an exhaust passage 23a, which will be described later, and the combustion chamber 7. The exhaust valve 21 is opened and closed by an exhaust side variable valve mechanism 22.

  Since the exhaust side variable valve mechanism 22 has the same configuration as the intake side variable valve mechanism 12 described above, detailed description thereof will be omitted, but the ECU 3 controls the excitation and de-excitation of the electromagnet so that the exhaust The opening / closing timing of the valve 21 is arbitrarily changed. Therefore, the ECU 3 can easily adjust the valve opening period of the exhaust valve 21.

  An exhaust pipe 23 is connected to the cylinder head 5 on the exhaust port 52 side. An exhaust passage 23 a communicating with the exhaust port 52 is formed in the exhaust pipe 23. The exhaust passage 23a is provided with an exhaust turbine 24 driven by an exhaust flow, a catalyst (not shown) for purifying the exhaust, and a muffler (not shown) for silencing.

  The exhaust turbine 24 is connected to the compressor 17. The power of the exhaust turbine 24 driven by the exhaust flow is used as power for the compressor 17 to compress air. The compressor 17 and the exhaust turbine 24 constitute a supercharger 9.

  A bypass passage 25 is provided between the upstream side and the downstream side in the exhaust direction in which the exhaust pipe 23 exhausts through the exhaust turbine 24. The bypass passage 25 is provided with a waste gate valve 26 capable of adjusting the exhaust flow to the exhaust turbine 24. The wastegate valve 26 can control the supercharging pressure that is the pressure of the intake air obtained by supercharging the supercharger 9 by adjusting the exhaust flow to the exhaust turbine 24. The waste gate valve 26 is configured by, for example, an electromagnetic valve, and is opened and closed by the ECU 3. The supercharging pressure may be controlled using a variable nozzle turbo capable of changing the supercharging pressure.

  The ECU 3 includes a computer unit that includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a flash memory, an input port, and an output port.

  The ROM of the computer unit stores a program for causing the computer unit to function as the ECU 3 along with various control constants and various maps. That is, the computer unit functions as the ECU 3 when the CPU executes a program stored in the ROM.

  In addition to the intake pressure sensor 15, the throttle opening sensor 41, the boost pressure sensor 42, and the intake air temperature sensor 43 described above, an air flow meter 44, a crank angle sensor 45, an exhaust pressure sensor 46, and an exhaust temperature are input to the input port of the ECU 3. Various sensors such as a sensor 47, an accelerator opening sensor 48, and an atmospheric pressure sensor 49 are connected.

  The air flow meter 44 detects the intake air amount. The crank angle sensor 45 outputs a rectangular crank angle signal for each predetermined crank angle as the engine 2 rotates. The ECU 3 calculates an engine speed that is the engine speed of the engine 2 based on the crank angle signal.

  The exhaust pressure sensor 46 detects the exhaust pressure. The exhaust temperature sensor 47 detects the temperature of the exhaust. The accelerator opening sensor 48 detects the amount of depression of an accelerator pedal (not shown) by the driver as the accelerator opening. The atmospheric pressure sensor 49 detects atmospheric pressure.

  On the other hand, various control objects including the above-described injector 10, throttle valve 19, waste gate valve 26, and spark plug 50 are connected to the output port of the ECU 3.

  The ECU 3 switches between SI combustion and HCCI combustion according to the operating state of the engine 2. Specifically, the ECU 3 determines whether the operation region of the engine 2 is in the SI combustion region or the HCCI combustion region by referring to a combustion region map using the engine speed and the engine required torque as parameters. Based on this determination, whether to perform SI combustion or HCCI combustion is selected.

  The ECU 3 calculates the driver's required torque based on the accelerator opening input from the accelerator opening sensor 48, the engine speed calculated from each crank signal input from the crank angle sensor 45, and the like.

  In the HCCI mode in which HCCI combustion is performed, the ECU 3 controls the engine 2 based on the target torque calculated from the driver request torque and the like, similarly to the engine in which SI combustion is performed.

  In a general SI combustion engine, as shown in FIG. 2, the target SLOW torque and the target FAST torque are calculated from the required torque from the driver, transmission, skid prevention device, and the like.

  In response to the target SLOW torque, a slow responsive air amount control device such as the throttle valve 19 is controlled, and the amount of fuel injected to be close to the theoretical air-fuel ratio is controlled in accordance with the amount of air actually entering the combustion chamber 7. Is done.

  Further, the ignition timing and the fuel cut with quick response are controlled so as to realize the target FAST torque.

  Normally, the target SLOW torque and the target FAST torque are the same value, and when the torque change is small, the ignition timing is controlled to a value that maximizes the combustion efficiency, but the torque increase rate depends on the response of the actual air amount. Because it depends, it cannot be increased rapidly.

  On the other hand, when it is necessary to increase the torque with high response when the load on the auxiliary machine increases, when shifting shock is suppressed, or when the skid prevention device is activated, the target SLOW torque is compared with the target FAST torque in advance. The ignition timing is retarded by increasing it, and the ignition timing is advanced when torque increase is required.

  In HCCI combustion, in order to operate while satisfying torque fluctuation, noise, and exhaust gas values, the compression end temperature and G / F are always controlled to the optimum values according to the fuel injection amount and engine speed. There is a need to.

  Further, since G / F has a range that can be operated in accordance with the fuel injection amount, the engine speed, and the like, supercharging is required under conditions where the fuel injection amount is relatively large (torque is large). Under the supercharging condition, the heat efficiency is generally the highest in a state where the G / F is minimum within the operable range. This is mainly due to the fact that the supercharging pressure is the lowest and the supercharging work is minimized.

  Further, the IVC (Intake Valve Closing timing) is set near the bottom dead center where the charging efficiency is maximized, so that the amount of supercharged work is minimized. In the non-supercharging condition, if the throttle valve 19 is throttled to reduce G / F (reduce the gas amount), the throttle loss increases. Alternatively, if the intake valve 11 is closed early or late in order to reduce the G / F, the compression end temperature decreases, and an increase in the amount of residual gas to compensate for this decreases the specific heat ratio or causes heat loss in the NVO. This leads to an increase, and in any case the thermal efficiency is reduced. For this reason, G / F is assumed to be within the range where operation is possible.

  For the above reason, the thermal efficiency is maximized under the condition that the IVC is set near the bottom dead center where the actual compression ratio can be obtained most, and the residual gas amount is the minimum amount that can realize the operable compression end temperature.

  In view of the above, in the present embodiment, in the HCCI combustion, the compression end temperature and the G / F are always controlled within the operable range, and the operation is performed as frequently as possible at a high thermal efficiency. Control is performed so that it can follow sudden changes in the required torque.

  As shown in FIG. 2, the ECU 3 serves as the target torque calculation unit 101 based on the driver required torque, the SLOW required torque of the transmission, the skid prevention device, and the FAST required torque, the state of the transmission, the skid prevention device, and the like. A target SLOW torque and a target FAST torque are calculated.

  FIG. 3 is a configuration diagram of a block for controlling the supercharger 9. As shown in FIG. 3, the ECU 3 calculates a target SLOW fuel amount from the target SLOW torque and the engine speed as the target fuel amount calculation unit 102.

  For example, the ECU 3 calculates the target SLOW fuel amount using a map in which the target SLOW fuel amount is determined from the target SLOW torque and the engine speed. This map is obtained by experiments or the like and stored in the ROM of the ECU 3.

  The target SLOW torque is calculated by the target torque calculation unit 101 described above. The engine speed is calculated from the crank angle signal output from the crank angle sensor 45.

  As shown in FIG. 3, the ECU 3 calculates a target G / F value from the target SLOW fuel amount and the engine speed as the target G / F calculation unit 103.

  For example, the ECU 3 calculates the target G / F value from a map in which the G / F value that maximizes the thermal efficiency is determined from the target SLOW fuel amount and the engine speed. This map is obtained by experiments or the like and stored in the ROM of the ECU 3.

  The target SLOW fuel amount is calculated by the target fuel amount calculation unit 102 described above. The engine speed is calculated from the crank angle signal output from the crank angle sensor 45.

  The G / F value at which the thermal efficiency is maximized is generally the smallest value in the range of operable G / F values in the supercharging region. Note that even in a region where supercharging is not required under normal atmospheric pressure, supercharging is required when the atmospheric pressure decreases, so that the G / F is the minimum fuel value that covers the possible supercharging region at the lowest atmospheric pressure. Set up the map.

  As shown in FIG. 3, the ECU 3 calculates the target boost pressure from the target mixture mass, target temperature before compression, IVC (intake valve closing timing), atmospheric pressure, and the like as the target boost pressure calculation unit 104.

  For example, the ECU 3 generally has a G / F value G (cylinder gas amount) that does not include fuel, so the target G / F value plus 1 is multiplied by the target SLOW fuel amount. Is the target mixture mass.

  For example, the ECU 3 calculates the target boost pressure using a map in which the target boost pressure is determined from the target mixture mass, the target temperature before compression, IVC, and atmospheric pressure. The target supercharging pressure has an atmospheric pressure as a lower limit. This map is obtained by experiments or the like and stored in the ROM of the ECU 3. In addition, you may make it correct | amend by the correction coefficient etc. to the value calculated | required by the map.

  The pre-compression target temperature is calculated by the pre-compression target temperature calculation unit 112 described later. The previous value is used for IVC. The atmospheric pressure is detected by the atmospheric pressure sensor 49. As described above, the IVC uses a value near the bottom dead center at which the filling efficiency is maximized as a control target.

  As shown in FIG. 3, the ECU 3 controls the wastegate valve 26 as the supercharger control unit 105 so that the obtained target supercharging pressure is obtained.

  FIG. 4 is a block diagram of a block for controlling the fuel injection amount. As shown in FIG. 4, the ECU 3 calculates the target fuel amount from the target FAST torque and the engine speed as the target fuel amount calculation unit 106.

  For example, the ECU 3 calculates the target fuel amount from a map in which the target fuel amount is determined from the target FAST torque and the engine speed. This map is obtained by experiments or the like and stored in the ROM of the ECU 3.

  The target FAST torque is calculated by the target torque calculator 101 described above. The engine speed is calculated from the crank angle signal output from the crank angle sensor 45.

  As shown in FIG. 4, the ECU 3 calculates the mixture mass from the actual intake pressure, the target temperature before compression, the IVC (intake valve closing timing), and the like as the mixture mass calculation unit 107.

  For example, the ECU 3 calculates the mixture mass based on a map in which the mixture mass is determined from the actual intake pressure, the target temperature before compression, and IVC. This map is obtained by experiments or the like and stored in the ROM of the ECU 3.

  The actual intake pressure is detected by the intake pressure sensor 15. The pre-compression target temperature is calculated by the pre-compression target temperature calculation unit 112 described later. The previous value is used for IVC. As described above, the IVC uses a value near the bottom dead center at which the filling efficiency is maximized as a control target.

  As shown in FIG. 4, the ECU 3 calculates a G / F lower limit value from the mixture gas mass and the engine speed as the G / F lower limit calculation unit 108.

  For example, the ECU 3 calculates the G / F lower limit value by using a map in which the G / F lower limit value is determined from the air-fuel mixture mass and the engine speed. This map is obtained by experiments or the like and stored in the ROM of the ECU 3.

  The air-fuel mixture mass is calculated by the air-fuel mixture mass calculating unit 107 described above. The engine speed is calculated from the crank angle signal output from the crank angle sensor 45.

  The ECU 3 calculates the upper limit value of the fuel amount by dividing the air / fuel mixture mass calculated by the air / fuel mixture mass calculating unit 107 by adding 1 to the G / F lower limit value.

  As shown in FIG. 4, the ECU 3 calculates a G / F upper limit value as the G / F upper limit calculation unit 109 from the mixture gas mass and the engine speed.

  For example, the ECU 3 calculates the G / F upper limit value using a map in which the G / F upper limit value is determined from the air-fuel mixture mass and the engine speed. This map is obtained by experiments or the like and stored in the ROM of the ECU 3.

  The air-fuel mixture mass is calculated by the air-fuel mixture mass calculating unit 107 described above. The engine speed is calculated from the crank angle signal output from the crank angle sensor 45.

  The ECU 3 calculates the lower limit value of the fuel amount by dividing the air / fuel mixture mass calculated by the air / fuel mixture mass calculating unit 107 by adding 1 to the G / F upper limit value.

  As shown in FIG. 4, the ECU 3 uses the fuel injection control unit 110 to set the final fuel amount as the fuel amount upper limit value when the target fuel amount is larger than the fuel amount upper limit value, and the target fuel amount is lower than the fuel amount lower limit value. If it is smaller, the final fuel amount is guarded with the fuel amount lower limit value, and the final fuel amount is calculated. Then, the ECU 3 controls the injector 10 as the fuel injection control unit 110 so as to inject the final fuel amount.

  The control of the fuel injection amount shown in FIG. 4 corresponds to the ignition timing control in SI combustion. Here, when the target G / F calculation unit 103 sets the G / F value to the minimum value within the operable range, the FAST torque exceeding the target SLOW torque cannot be realized as in the SI combustion. For this reason, the response of torque becomes slow.

  Therefore, when it is necessary to increase the torque with a high response, the target SLOW torque is made higher than the target FAST torque in advance (about the target torque after the increase) in the same manner as SI combustion.

  In this way, the G / F is increased by increasing the boost pressure corresponding to the target SLOW torque, the fuel injection amount is decreased corresponding to the target FAST torque, and the torque needs to be increased. At this time, the torque can be increased with high response by increasing the fuel injection amount.

  The G / F lower limit value calculated by the G / F lower limit calculation unit 108 is the same value as the target G / F value calculated by the target G / F calculation unit 103 under the supercharging condition. Also, under non-supercharging conditions, this control can be applied even during switching to SI combustion by adopting a value measured by reducing the mass of the air-fuel mixture by, for example, throttle the throttle valve 19.

  FIG. 5 is a configuration diagram of a block that controls the intake valve 11 and the exhaust valve 21. As shown in FIG. 5, the ECU 3 calculates the compression end target temperature from the target fuel amount and the engine speed as the compression end target temperature calculation unit 111.

  For example, the ECU 3 calculates the compression end target temperature using a map in which the compression end target temperature is determined from the target fuel amount and the engine speed. This map is obtained by experiments or the like and stored in the ROM of the ECU 3.

  The target fuel amount is calculated by the target fuel amount calculation unit 106 described above. The engine speed is calculated from the crank angle signal output from the crank angle sensor 45.

  As shown in FIG. 5, the ECU 3 calculates a pre-compression target temperature from the compression end target temperature, IVC (intake valve closing timing), combustion chamber wall surface temperature, and the like as the pre-compression target temperature calculation unit 112.

  The ECU 3 calculates the pre-compression target temperature, for example, assuming a polytropic change due to the actual compression ratio of the engine 2. In addition, when the heat radiation from the air-fuel mixture to the combustion chamber wall surface is large after the fuel cut has continued for a long time, correction by the combustion chamber wall surface temperature may be performed.

  The compression end target temperature is calculated by the compression end target temperature calculation unit 111 described above. The previous value is used for IVC. As described above, the IVC uses a value near the bottom dead center at which the filling efficiency is maximized as a control target.

  Since it is difficult to actually measure the combustion chamber wall surface temperature, the combustion chamber wall surface temperature is calculated by a model using the intake gas temperature, the exhaust stroke gas temperature, and the like. The intake gas temperature is detected by the intake temperature sensor 43.

  Since it is difficult to actually measure the exhaust stroke gas temperature, the exhaust stroke gas temperature is calculated by a model using the fuel amount, G / F, and the like.

  As shown in FIG. 5, the ECU 3 calculates the residual gas target mass from the pre-compression target temperature, the mixture gas mass, the intake gas temperature, the exhaust stroke gas temperature, and the combustion chamber wall surface temperature as the residual gas target mass calculation unit 113.

  For example, the ECU 3 calculates the residual gas target mass assuming that the amount of heat for heating the intake gas to the target temperature before compression and the amount of heat for cooling the residual gas to the target temperature before compression are the same.

  The target temperature before compression is calculated by the target temperature calculation unit 112 before compression described above. The air-fuel mixture mass is calculated by the air-fuel mixture mass calculating unit 107 described above. The intake gas temperature is detected by the intake temperature sensor 43. The exhaust stroke gas temperature and the combustion chamber wall surface temperature are calculated by the method described above.

  It should be noted that the temperature of the residual gas and the exhaust stroke gas at the time of IVO differ depending on the heat escaping from the residual gas compressed in NVO to the combustion chamber wall surface, the difference between the intake pressure and the exhaust pressure, etc. For the sake of simplicity, the residual gas mass may be calculated as the same, and correction may be performed by the combustion chamber wall surface temperature or the difference between the intake pressure and the exhaust pressure.

  As shown in FIG. 5, the ECU 3 controls the exhaust valve 21 as the exhaust valve control unit 114 based on the residual gas target mass, the exhaust pressure, the exhaust stroke gas temperature, and the like.

  The ECU 3 controls the residual gas mass to become the residual gas target mass by changing, for example, EVC (exhaust valve closing timing).

  The ECU 3 controls the exhaust valve 21 by calculating EVC based on a map in which the residual gas mass is determined from the valve timing, the exhaust pressure, and the exhaust stroke gas temperature, for example. This map is obtained by experiments or the like and stored in the ROM of the ECU 3.

  The exhaust pressure is detected by an exhaust pressure sensor 46. The exhaust stroke gas temperature is calculated by the method described above.

  As shown in FIG. 5, the ECU 3 controls the intake valve 11 as an intake valve control unit 115 based on EVC (exhaust valve closing timing), intake pressure, exhaust pressure, exhaust stroke gas temperature, and the like.

  For example, the ECU 3 controls the IVO (Intake Valve Opening timing) so that the pressure of the residual gas during the NVO (negative valve overlap) period becomes equal to the intake pressure.

  For example, the ECU 3 calculates an IVO at which the combustion chamber pressure becomes equal to the intake pressure, assuming a polytropic change in compression and expansion in the NVO from the exhaust pressure and the combustion chamber volume at the EVC.

  The intake pressure is detected by the intake pressure sensor 15. The exhaust pressure is detected by an exhaust pressure sensor 46. The exhaust stroke gas temperature is calculated by the method described above.

  By doing so, it is possible to minimize the backflow of residual gas to the intake port 51 and the pumping loss associated with the inflow of intake air, and it is possible to reduce intake noise.

  As described above, in the above-described embodiment, the target air-fuel mixture mass that achieves the target SLOW torque is calculated, the supercharging pressure is controlled to achieve the target air-fuel mixture mass, and the fuel amount is set so as to achieve the target FAST torque. Is provided, and ECU 3 for controlling the fuel injection amount is provided.

  As a result, when it is necessary to increase the torque with a high response, the target torque can be made to follow the sudden change in the required torque by setting the target SLOW torque higher than the target FAST torque, and stable combustion can be achieved. Can be secured.

  Further, the ECU 3 calculates the upper limit value and lower limit value of the G / F based on the mass of air-fuel mixture calculated from the actual intake pressure, and calculates the upper limit value and lower limit value of the fuel amount from the upper limit value and lower limit value of the G / F. Calculate to limit the fuel injection amount.

  Thereby, it is possible to suppress the occurrence of misfire and torque fluctuation under various conditions such as when the torque changes or after returning from the fuel cut, and to suppress the increase in noise and NOx emission.

  Further, the ECU 3 calculates the compression end target temperature based on the target fuel amount calculated based on the target FAST torque, calculates the residual gas target mass so as to be the compression end target temperature, and sets the residual gas target mass to this residual gas target mass. EVC and IVO are controlled so that

  Thereby, it is possible to suppress the occurrence of misfire and torque fluctuation under various conditions such as when the torque changes or after returning from the fuel cut, and to suppress the increase in noise and NOx emission.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

1 vehicle 2 engine (internal combustion engine)
3 ECU (control unit)
DESCRIPTION OF SYMBOLS 9 Supercharger 10 Injector 11 Intake valve 12 Intake side variable valve mechanism 15 Intake pressure sensor 17 Compressor 21 Exhaust valve 22 Exhaust side variable valve mechanism 24 Exhaust turbine 25 Bypass passage 26 Westgate valve 41 Throttle opening sensor 42 Supercharge Pressure sensor 43 Intake temperature sensor 45 Crank angle sensor 46 Exhaust pressure sensor 47 Exhaust temperature sensor 48 Accelerator opening sensor 49 Atmospheric pressure sensor 101 Target torque calculation unit 102 Target fuel amount calculation unit 103 Target G / F calculation unit 104 Target supercharging pressure Calculation unit 105 Supercharger control unit 106 Target fuel amount calculation unit 107 Gas mixture mass calculation unit 108 G / F lower limit calculation unit 109 G / F upper limit calculation unit 110 Fuel injection control unit 111 Compression end target temperature calculation unit 112 Pre-compression target Temperature calculator 113 Residual gas target mass calculation 114 exhaust valve control unit 115 intake valve control unit

Claims (3)

A control device for an internal combustion engine that performs premixed compression self-ignition combustion,
When it is necessary to increase the torque with a high response, the internal combustion engine includes a control unit that controls the mass of the air-fuel mixture so that the target torque after the increase is reached and controls the fuel injection amount so as to be the current target torque. Control device.   2. The control device for an internal combustion engine according to claim 1, wherein the control unit limits the fuel injection amount based on an air-fuel mixture mass calculated from a current intake pressure.   3. The control unit according to claim 1, wherein the control unit calculates a residual gas target mass based on the current target torque, and adjusts an opening / closing timing of at least one of the intake valve and the exhaust valve so as to be the residual gas target mass. The internal combustion engine control device described.

Images