JP5046190B2 - In-cylinder injection internal combustion engine control device - Google Patents

Description

  The present invention relates to a control device for a direct injection internal combustion engine, and more particularly to a direct injection internal combustion engine that controls fuel injection timing and suppresses knocking in a direct injection internal combustion engine that directly injects fuel into a combustion chamber. The present invention relates to a control device.

In a cylinder injection type internal combustion engine for in-vehicle use, fuel in a fuel tank is pumped by a low-pressure side electromagnetic fuel pump, and this low-pressure fuel is made high-pressure by a high-pressure side mechanical fuel pump. High pressure fuel is distributed by a delivery pipe and directly injected from a fuel injection valve into a combustion chamber.
Such a direct injection internal combustion engine control device includes a fuel supply device capable of supplying fuel directly into the combustion chamber, and controls the fuel injection amount in accordance with various states including an internal state. There are some equipped with a control means having a fuel injection function for performing control so that fuel injection is divided into a plurality of times under predetermined conditions.

2. Description of the Related Art Conventionally, a control device for a direct injection internal combustion engine includes a fuel injection system that performs fuel injection based on a difference between an actual ignition timing when knocking is detected and an estimated optimal ignition timing under the operating conditions. In addition, there are some which change at least one of the injection pressure, the injection timing, and the injection ratio.
The internal combustion engine control device includes a first region when the engine operating state is in a predetermined first region where cooling of the intake air in the combustion chamber is required in the direct injection internal combustion engine. Compared to the case where the fuel injection rate is in a predetermined second region other than the above, there is a fuel injection rate that is reduced, and the injection time is increased by that amount, which is advantageous for cooling the intake air in the combustion chamber.
JP 2006-329158 A Japanese Patent Laid-Open No. 2007-40205

Conventionally, in an internal combustion engine with a high compression ratio, or an internal combustion engine under engine operating conditions such as a low rotation and high load, knocking that tends to damage the components of the internal combustion engine occurs. Knocking is suppressed by using retard angle control, valve timing control of variable valve mechanism, etc., but these knocking suppression methods have the adverse effect of lowering the performance of the internal combustion engine, so improvement is desired. It was.
Further, the direct injection internal combustion engine injects fuel directly into the combustion chamber, thereby making it possible to reduce the mixture temperature by using the latent heat of vaporization caused by the evaporation of the fuel. Compared to a port injection type internal combustion engine, knocking is less likely to occur. On the other hand, knocking that greatly affects the performance of the internal combustion engine is greatly affected by the mixture temperature in the combustion chamber, and the lower the mixture temperature from the intake stroke to the compression stroke, the lower the post-compression stroke (just before ignition). The mixture temperature becomes low and it is difficult to generate.
Generally, in order to lower the mixture temperature after the compression stroke that greatly affects the occurrence of knocking, it is effective to lower the mixture temperature at the start of the compression stroke. Therefore, if all the injected fuel can be vaporized in synchronism with the closing timing of the intake valve, the temperature of the mixture after the compression stroke can be reduced efficiently. However, if all the fuel is injected in the vicinity of the closing timing of the intake valve, the homogeneity of the air-fuel mixture may be reduced, leading to a decrease in the performance of the internal combustion engine.
Further, in the above-mentioned patent document, the ignition timing is advanced in parallel with the fuel injection, while the main injection, which is the first injection of the divided injection, is blown to the extent that some deviation is included at an early stage. In other words, if it blows mostly (roughly) and knocking occurs, it will finely adjust the divided injection performed in the latter period, and the latter part of the divided injection will be adjusted during the compression stroke, especially in the latter period. Even if it is the structure to perform, although there exists an effect which cools the air-fuel | gaseous mixture in a combustion chamber, there was room for improvement from the point of the cooling efficiency of air-fuel | gaseous mixture.
Furthermore, in the past, even in the case of late injection of split injection, the purpose is not to cool the air-fuel mixture in the combustion chamber, but to stratify the fuel concentration distribution in the combustion chamber. It may be intended to generate a rich air-fuel mixture around the plug, and has an effect of cooling the air-fuel mixture when it is injected in the compression stroke. However, it is the same as the above-mentioned patent document that there is room for further improvement in terms of the cooling efficiency of the air-fuel mixture.
Furthermore, in a cylinder injection internal combustion engine, generally, there is an effect of cooling the air-fuel mixture even in the injection in the intake stroke. However, if the injection timing is too early, the average temperature is increased by the subsequent charging air and the charging efficiency is lowered. On the other hand, if the injection timing is late, it cannot be cooled when the charging efficiency is increased. Therefore, it is the same as the above-mentioned patent document that there is room for further improvement in terms of the cooling efficiency of the air-fuel mixture.

  Therefore, the object of the present invention is to reduce the temperature of the mixture before the compression, by reducing the temperature of the mixture in the combustion chamber and preventing abnormal combustion in the process from the compression stroke to the ignition, especially the occurrence of knocking, the prevention of smoke, and the compression. It is an object of the present invention to provide a control device for a direct injection internal combustion engine that increases the efficiency including a temperature rise accompanying compression.

The present invention includes a fuel supply device capable of supplying fuel directly into a combustion chamber of an internal combustion engine, controls the fuel injection amount in accordance with various states including the internal state of the internal combustion engine, and performs fuel injection under a predetermined condition. In a control apparatus for a direct injection internal combustion engine provided with a control means having a fuel injection function that performs control so as to be divided into a plurality of times, the internal combustion engine is provided with a variable valve mechanism for changing the opening and closing timing of the intake valve, The control means has a phase control function to change and control the opening / closing timing of the intake valve so as to advance and retard according to various conditions including artificial operation and emission conditions. The fuel injection is divided during the intake valve opening period, and the final fuel injection is completed for a predetermined time before the closing timing of the intake valve. Taking into account the time required for vaporization of the injection amount and sets the predetermined time from the injection amount of the final split injection.

The control device for a direct injection internal combustion engine according to the present invention reduces the temperature of the air-fuel mixture in the combustion chamber, thereby preventing abnormal combustion in the process from the compression stroke to the ignition time, particularly knocking, smoke, and before compression. The efficiency of the gas mixture can be increased by lowering the temperature of the air-fuel mixture, including the temperature rise accompanying compression.
In particular, in the latter-stage injection of split injection, the efficiency is improved so as to obtain the maximum cooling effect of the air-fuel mixture with a small fuel distribution, and the control means is prevented from becoming complicated due to an increase in control parameters. Control accuracy can be increased by preventing an increase in load.

The purpose of the present invention is to prevent abnormal combustion in the process from the compression stroke to ignition, in particular, to prevent knocking, to prevent the occurrence of smoke, to lower the mixture temperature before compression, and to increase the efficiency including the temperature increase due to compression, This is achieved by lowering the temperature of the mixture in the combustion chamber.
Embodiments of the present invention will be described in detail and specifically with reference to the drawings.

1 to 9 show an embodiment of the present invention.
In FIG. 6, reference numeral 1 denotes an in-vehicle and multi-cylinder direct injection internal combustion engine (hereinafter referred to as “internal combustion engine”), and 2 is a control device for the internal combustion engine 1.
As shown in FIGS. 6 and 7, the internal combustion engine 1 includes a cylinder block 3, a cylinder head 4, and a cylinder head cover 5 that are integrally formed. A cylinder (cylinder) 6 is formed in the cylinder block 3, and a piston 7 is slidably provided in the cylinder 6.
In the internal combustion engine 1, as shown in FIG. 7, a combustion chamber 8 is formed by the cylinder 6, the piston 7, and the cylinder head 4 of the cylinder block 3. The piston 7 is connected to a crankshaft 10 (see FIG. 8) via a connecting rod 9.
In the cylinder head 4, an intake port 12 having an intake port 11 is formed on the intake side so as to communicate with the combustion chamber 8, and an exhaust port 14 having an exhaust port 13 is formed on the exhaust side. Has been. In addition, a spark plug 15 facing the combustion chamber 8 is attached to the cylinder head 4 so as to be directed in the vertical direction at the central portion.

The cylinder head 4 is provided with a valve mechanism 16. In this valve operating mechanism 16, on the intake side, an intake cam shaft 17 is supported by an intake cam cap 18, and an intake valve 19 driven by the intake cam shaft 17 is provided via an intake tappet 20. The cylinder head 4 is provided with an exhaust cam shaft 21 supported by an exhaust cam cap 22 on the exhaust side, and an exhaust valve 23 driven by the exhaust cam shaft 21 via an exhaust tappet 24.
The intake valve 19 can reciprocate by the resilient force of the intake spring 27 held between the intake spring seat portion 25 fixed to the intake valve 19 and the intake head wall portion 26 of the cylinder head 4. 11 is opened and closed.
The intake valve 19 basically has a crank angle of 180 ° or more from the opening timing (intake valve opening timing) to the closing timing (intake valve closing timing). The opening time of the intake valve 19 is an intake stroke of the internal combustion engine 1 and changes by being advanced and retarded by a variable valve mechanism 83 described later. The intake stroke of the internal combustion engine 1 includes a top dead center (TDC, 0 °, ± 360 ° (its 360 ° cycle)) and a bottom dead center (BDC, ± 180 ° (a 360 ° cycle)) corresponding to the crank angle. ).
The exhaust valve 23 can reciprocate by the resilient force of the exhaust spring 30 held between the exhaust spring seat 28 fixed to the exhaust valve 23 and the exhaust head wall 29 of the cylinder head 4. 13 is opened and closed.

As shown in FIG. 6, on the intake side of the internal combustion engine 1, an air cleaner 31, an intake pipe 32 that guides intake air from the air cleaner 31 to the combustion chamber 8 side, a throttle body 34 that includes a throttle valve 33, a surge An intake manifold 36, to which the tank 35 is integrated and attached to the cylinder head 4, is sequentially connected. Further, in the middle of the intake pipe 32, the supercharger 37 that supercharges intake air in order from the air cleaner 31 side and supplies it into the combustion chamber 8, and cools the intake air supercharged by the supercharger 37. An intercooler 38 is attached. Thus, the intake pipe 32 includes a first intake pipe portion 32A between the air cleaner 31 and the supercharger 37, a second intake pipe portion 32B between the supercharger 37 and the intercooler 38, and between the intercooler 38 and the throttle body 34. It is divided into a third intake pipe portion 32C.
The throttle valve 36 controls the amount of intake air into the combustion chamber 8 and may be an electronically controlled throttle valve. If the sudden change is suppressed or the wasteful full load state is reduced, the throttle valve 36 Response is stable and more stable control is possible.

  On the other hand, on the exhaust side of the internal combustion engine 1, an exhaust manifold 39 attached to the cylinder head 4 so as to guide exhaust from the internal combustion engine 1, a catalytic converter 40, and an exhaust pipe 41 are sequentially connected.

The supercharger 37 is disposed in the supercharger case 42 between the compressor 43 disposed between the first intake pipe portion 32A and the second intake pipe portion 32B, and between the exhaust manifold 39 and the catalytic converter 40. And a turbine 44 that drives the compressor 43 by an exhaust flow, and the compressor 43 and the turbine 44 are connected by a turbo shaft 45. The exhaust amount to the turbine 44 is adjusted by the waste gate mechanism 46.
The wastegate mechanism 46 includes an opening / closing valve 48 for opening / closing a supercharging bypass passage 47 formed in the supercharger case 42 so as to bypass the turbine 44, a valve actuator 49 for operating the opening / closing valve 48, An actuator pressure passage 50 communicating with the valve actuator 49 and the first intake pipe portion 32A, and a wastegate control valve (VSV) provided in the actuator pressure passage 50 for controlling the air pressure to the valve actuator 49 51.

  The intake pipe 32 is provided with a pressure adjusting device 52 that adjusts the intake pressure upstream and downstream of the supercharger 37. The pressure adjusting device 52 is provided in the middle of the pressure adjusting passage 53 and the pressure adjusting passage 53 that communicates the first intake pipe portion 32A and the second intake pipe portion 32B so as to bypass the supercharger 37. A pressure adjustment valve 54, a pressure communication passage 55 communicating the pressure adjustment valve 54 and the second intake pipe portion 32B, and a pressure control valve 56 provided in the middle of the pressure communication passage 55 are provided.

The internal combustion engine 1 is provided with a fuel supply device 57. The fuel supply device 57 can supply fuel directly into the combustion chamber 8 of the internal combustion engine 1, and includes a low pressure fuel mechanism 58 and a high pressure fuel mechanism 59.
The low pressure fuel mechanism 58 is provided with an electromagnetic fuel pump 61 on the low pressure side in the fuel tank 60, and a pressure regulator 63 is connected to the electromagnetic fuel pump 61 via an oil filter 62. One end of the side fuel supply passage 64 is connected. The electromagnetic fuel pump 61 pumps the fuel in the fuel tank 60 to the internal combustion engine 1 side.
The high pressure fuel mechanism 59 is provided with a high pressure side mechanical fuel pump 65 at the other end of the low pressure side fuel supply passage 64. The mechanical fuel pump 65 is mechanically driven by the rotation of the exhaust camshaft 21, and increases the low-pressure fuel from the electromagnetic fuel pump 61 side to the fuel injection valve 69 described later. A fuel return passage 66 opened in the fuel tank 60 is connected to the mechanical fuel pump 65.
In addition, one end of a high-pressure side fuel supply passage 67 is connected to the mechanical fuel pump 65. The other end of the high pressure side fuel supply passage 67 is connected to a delivery pipe 68 attached to the cylinder head 4. A fuel injection valve 69 attached to the cylinder head 4 is connected to the delivery pipe 68.
The fuel injection valve 69 is attached to the combustion chamber 8 along with the intake port 12 on the intake side, and generates a tumble flow in the fuel during the intake stroke of the internal combustion engine 1 (see FIG. 7).
The fuel injection valve 69 directly injects fuel into the combustion chamber 8 in accordance with an injection pulse determined by the control means 122 described later. As shown in FIG. 6, the fuel injection valve 69 is in communication with a fuel injection driver 70 that increases the voltage to the fuel injection valve 69.
In this fuel supply device 57, by directly injecting fuel into the combustion chamber 8, the latent heat of vaporization of the fuel lowers the temperature of the mixture in the combustion chamber 8, improving the charging efficiency and improving the anti-knock performance. In addition, since the compression ratio (maximum compression ratio) can be set to a high value, high torque and high output can be achieved and the combustion speed is fast, a large amount of EGR control is performed by the EGR device 80 described later. Stable combustion is possible even if exhaust is introduced, and NOG and pumping loss (pump loss) are reduced by performing EGR control in a wide operating range, exhaust gas purification performance is improved, and fuel consumption is reduced. .

  The internal combustion engine 1 is provided with an evaporated fuel control device 71. In this evaporated fuel control device 71, a two-way check valve 72 is attached to the fuel tank 60, one end of an evaporation passage 73 is connected to the two-way check valve 72, and a canister 74 is provided at the other end of the evaporation passage 73. One end of a purge passage 75 is connected to the canister 74, the other end of the purge passage 75 is communicated with the throttle body 34 downstream of the throttle valve 33, and a purge valve (VSV) 76 is provided in the middle of the purge passage 75. Is provided.

  The internal combustion engine 1 is provided with an idle speed control device 77. In this idle speed control device 77, an idle air passage 78 is provided so as to bypass the throttle valve 33 and communicate the inside of the throttle body 34 and the surge tank 35, and the combustion chamber 8 is provided in the middle of the idle air passage 78. An ISC valve (idle air amount control valve) 79 that adjusts the amount of idle air is provided.

  Further, the internal combustion engine 1 is provided with an EGR device 80. In the EGR device 80, an EGR passage 81 that communicates the surge tank 35 and the exhaust manifold 39 is provided, and an EGR valve 82 is provided in the middle of the EGR passage 81. The EGR device 80 determines a target opening degree of the EGR valve 82 according to the state of the engine speed and the intake pipe pressure and adds a water temperature correction to the target opening degree to optimally control the opening degree of the EGR valve 82, which will be described later. The control means 122 is operated.

Further, the internal combustion engine 1 is provided with a variable valve mechanism (VVT) 83 as shown in FIG. The variable valve mechanism 83 changes the opening / closing timing of the intake valve 19, and is a hydraulic control type variable valve mechanism with a hydraulic control valve (OCV) interposed therein or an electric control type variable valve mechanism with an electric motor interposed. Etc.
In this embodiment, as shown in FIG. 8, the variable valve mechanism 83 is of a hydraulic control type and includes a hydraulic actuator 84 and a hydraulic control valve (OCV) 85.
The hydraulic actuator 84 includes an actuator sprocket 86 connected to the crank sprocket of the crankshaft 10 via a timing chain, an actuator case 88 attached to the intake camshaft 17 together with the actuator sprocket 86 by a mounting bolt 87, and the actuator case 88 And a rotor 89 disposed inside. An advance chamber 90 and a retard chamber 91 are formed in the actuator case 88.
The hydraulic control valve 85 includes a valve main body 92. The valve main body 92 is formed with a solenoid accommodating portion 94 for accommodating the solenoid 93 therein and a spool hole 96 for sliding the spool valve 95, and a hydraulic pressure introduction port 97 communicating from the spool hole 96 to the outside. The advance port 98, the retard port 99, and the drain port 100 are formed in parallel.
In the hydraulic control valve 85, a solenoid 93 is excited / de-energized by a duty control signal from the control means 122 described later, and the spool valve 95 is reciprocated by the solenoid 93 so that the hydraulic introduction port 97, the advance port 98, and the delay are delayed. The corner opening 99 and the drain opening 100 are switched as required.
A hydraulic pressure introduction passage 101 communicating with the oil filter 62 is connected to the hydraulic pressure introduction port 97 of the hydraulic control valve 85. The advance chamber 90 of the hydraulic actuator 84 and the advance port 98 of the hydraulic control valve 85 are connected by an advance chamber passage 102. The retard chamber 91 of the hydraulic actuator 84 and the retard port 99 of the hydraulic control valve 85 are connected by a retard chamber passage 103. A drain passage 105 communicating with the oil pan 104 is connected to the drain port 100 of the hydraulic control valve 85.
In this variable valve mechanism 83, a mechanism that changes the phase of the intake camshaft 17 with respect to the reference position of the crankshaft 10 is applicable. Therefore, in this embodiment, the control means 122 (to be described later) changes the phase of the opening / closing timing of the intake valve 19 so as to advance and retard in accordance with various engine operating conditions including artificial operation and emission conditions. Have a phase control function to control.
Further, by the operation of the variable valve mechanism 83, the intake stroke and the compression stroke change with respect to the crank angle, and the ignition timing also changes.
As shown in FIG. 9, in the variable valve mechanism 83, by retarding the phase of the intake valve 19, the bottom dead center (BDC) is straddled, so that the substantial compression stroke is shortened and the actual compression is performed. The ratio changes. This becomes a high expansion ratio system in which the expansion stroke is longer than the compression stroke because of the relationship with the expansion stroke in which the phase of the intake valve 19 does not change, and contributes to higher efficiency of the internal combustion engine 1. On the other hand, when the phase of the intake valve 19 is advanced, the top dead center (TDC) is crossed and the phase overlaps with the phase of the exhaust valve 23 (indicated by “valve overlap” in FIG. 9). Will increase. Implementing this phase control (operation of VVT, etc.) according to the engine speed is achieved by balancing the improvement of power performance (particularly torque), fuel efficiency and exhaust gas reduction over the entire operation range of the internal combustion engine 1. To contribute.
The variable valve mechanism 83 may be configured by selectively changing a multi-stage cam such as a two-stage or a three-stage, or may have a variable valve lift (VVL) function. The present invention is applicable if at least the closing timing of the intake valve 19 has a function capable of changing the phase with respect to the bottom dead center of the piston 7 (corresponding crank angle).

  Further, as shown in FIG. 6, an ignition coil 106 connected to the spark plug 15 and a PCV valve 107 are attached to the cylinder head cover 5 of the internal combustion engine 1. A tank side blow-by gas passage 108 communicating with the inside of the surge tank 35 is connected to the PCV valve 107. The cylinder head cover 5 is connected to a cleaner-side blow-by gas passage 109 that communicates with the first intake pipe portion 32 </ b> A immediately downstream of the air cleaner 31.

As shown in FIG. 8, the internal combustion engine 1 is provided with a crank angle sensor 110 that detects the crank angle of the crankshaft 10 and a cam angle sensor 111 that detects the cam angle of the intake camshaft 17. The crank angle sensor 110 has a function of detecting the crank angle, causing the control means 122 (to be described later) to determine the start timing of fuel injection, and detecting the engine speed, and a mechanical fuel pump based on the engine speed. The fuel discharge amount from 65 is calculated.
Further, as shown in FIG. 6, the internal combustion engine 1 includes an air flow sensor 112 that is attached to the first intake pipe portion 32 </ b> A and detects an intake air amount, and a fuel that is attached to the delivery pipe 68 and that is supplied to the fuel injection valve 69. A fuel pressure sensor 113 for detecting the pressure (fuel pressure) of the engine, a water temperature sensor 115 for detecting the coolant temperature in the coolant passage 114 formed in a part of the intake manifold 36 as the engine temperature, and knocking in the combustion chamber 8 are detected. A knock sensor 116 is attached. The fuel pressure sensor 113 determines the fuel pressure correction value by the control means 122 described later. The air flow sensor 112 and the water temperature sensor 115 determine the fuel injection amount by the control means 122 described later.
The throttle body 34 is provided with a throttle sensor 117 that detects the throttle opening of the throttle valve 33, and one end of the pressure guiding passage 118 is connected downstream of the throttle valve 33. An intake pressure sensor 119 for detecting the intake pipe pressure downstream of the throttle valve 33 is provided at the other end of the pressure guide passage 118. The intake pressure sensor 119 determines the fuel injection amount by the control means 122 described later.
An intake air temperature sensor 120 that detects the temperature of intake air is attached to the surge tank 35. The intake air temperature sensor 120 determines the intake air temperature correction value by the control means 122 described later.
The catalytic converter 40 is provided with an oxygen sensor (O2 sensor) 121 for detecting the oxygen concentration in the exhaust gas.

Wastegate control valve 51, pressure control valve 56, electromagnetic fuel pump 61, fuel injection valve driver 70, purge valve 76, ISC valve 79, EGR valve 82, hydraulic control valve 85, ignition coil 106, crank angle sensor 110, and cam The angle sensor 111, the air flow sensor 112, the fuel pressure sensor 113, the water temperature sensor 115, the knock sensor 116, the throttle sensor 117, the intake pressure sensor 119, the intake temperature sensor 120, and the oxygen sensor 121 communicate with the control means (ECM) 122. Yes.
Further, the control means 122 communicates with a battery 125 via a main switch 123 and a fuse 124. The control means 122 can detect the battery voltage of the battery 125.
Each device such as the fuel supply device 57 and the variable valve mechanism 83 can be configured by CAN, communication, or the like.

The control means 122 has a fuel injection function of controlling the fuel injection amount in accordance with various states including the internal state of the internal combustion engine 1 and controlling the fuel injection to be divided into a plurality of times under a predetermined condition.
Further, the control means 122 has a phase control function for changing and controlling the opening / closing timing of the intake valve 19 so as to advance and retard according to various conditions including an artificial operation and an emission condition.
The control means 122 divides fuel injection during the opening period of the intake valve 19 to be changed (divided injection during the intake stroke), and performs the final fuel injection for a predetermined time before the intake valve closing timing. The predetermined time is set in consideration of the time (evaporation time) required for vaporization of the final injection amount after the full injection is completed. The predetermined time is a late injection time of the divided injection, and is a fuel evaporation time including a knock suppression injection period and a fuel vaporization period, which will be described later.
Further, the control means 122 sets the number of divided injections to two, and distributes the injection amount in the first main injection and the injection amount in the last divided injection according to predetermined engine operating conditions including the engine speed and the engine load. change.
Further, the control means 122 obtains the time required for vaporizing the final injection amount from the injection amount of the final divided injection determined by the distribution from the engine operating conditions, and the closing timing of the intake valve 17 that changes with the phase control. Based on the above, control is performed to start the last fuel injection of the division.
Here, the split injection is to split and inject all fuel injections required for one combustion cycle of one cylinder.

  For this reason, as shown in FIG. 6, the control means 122 includes a fuel injection control unit 122 </ b> A and an ignition timing control unit 122 </ b> B that implement each of the fuel injection controls described above.

In the fuel injection control unit 122A of the control means 122, in the split injection of the fuel injection, the first injection (main injection) of the divided injection and the latter injection (last injection, sub injection) of the divided injection at the total injection amount in one cycle. Is determined with reference to a table (map) set according to the engine speed and the engine load. In this case, a table corrected according to temperature conditions such as cooling water temperature, which is the engine temperature, may be provided.
The fuel vaporization period (vaporization delay time) corresponding to the fuel injection amount of knock suppression injection, which is the late injection of split injection, is shown in FIG. 2 as a period after the end of the knock suppression injection period for convenience. Since the fuel vaporization starts immediately after the start of the knock suppression injection, the total period of the knock suppression injection period and the fuel vaporization period in FIG. 2 is a substantially correct fuel vaporization period (evaporation time).
The normal injection control after the internal combustion engine 1 is started basically performs sequential injection with the injection timing as a predetermined timing of the intake stroke based on a signal from the cam angle sensor 111. The fuel injection time corresponding to the fuel injection amount is determined based on the intake pipe pressure and the engine speed, and the basic injection time is corrected by signals from each sensor. Determine the correct fuel injection time. Fuel injection amount determined from the engine operating condition (the sum of the split injection) is assumed, including various correction.
The correction of this fuel injection control is an intake air temperature correction that corrects the difference in air density due to a change in intake air temperature, the fuel injection amount is increased according to the cooling water temperature during cooling, and the correction amount is gradually decreased as the warm-up progresses. Warm-up correction, atmospheric pressure correction that corrects the deviation of air-fuel ratio caused by changes in atmospheric pressure, throttle opening correction that corrects fuel injection time according to changes in throttle opening, acceleration and deceleration state detection, acceleration Increase the correction amount to improve acceleration performance at the time, and reduce the correction amount at the time of deceleration to reduce the exhaust gas and improve fuel efficiency by accelerating increase / decrease / decrease correction, change the air / fuel ratio when EGR is introduced or EGR cut EGR correction for correcting, air-fuel ratio (A / F) correction for correcting deviation from the target air-fuel ratio in each operating region, feedback correction for correcting the air-fuel ratio to the stoichiometric air-fuel ratio from the oxygen concentration in the exhaust gas, This includes various corrections such as a learning correction that corrects the base air twist ratio that shifts due to a yearly change, etc., to keep it near the theoretical air-fuel ratio, and a purge concentration correction that corrects the change in the air-fuel ratio when evaporative fuel is introduced or when evaporative fuel is cut. .
In this case, all of the divided injections are injections in the intake stroke, and there is no injection at a later time, so that smoke is hardly generated and the air-fuel mixture can be made homogeneous.

  In the correction of the fuel injection, the main injection which is the first injection of the divided injection may be further divided into a plurality of parts. The nozzle of the fuel injection valve 69 provided facing the combustion chamber may be improved so that the dispersion of the spray is directed to a desired distribution state and optimized in the combustion chamber. Another fuel injection valve provided in the intake port 12 may be provided side by side, and the first-stage injection of split injection may be performed by another fuel injection valve provided in the intake port 12. In order to correct the fuel injection, the internal combustion engine 1 is increased immediately after the start, and then the correction amount is gradually decreased to correct the increase immediately after the start to smooth the drivability, and to correct the injection timing delay due to the decrease in the battery voltage. Depending on how the battery voltage drops, voltage correction for extending the energization time to the fuel injection valve 69 and fuel pressure correction for correcting increase / decrease in the injection amount due to fluctuations in fuel pressure may be included. In addition, in the intake stroke, the faster the intake flow velocity, the easier the atomization of the fuel and the homogenized mixing with the fresh air proceed. For this reason, another device may be provided. For example, on the low rotation side of the internal combustion engine 1, it is possible to change the valve lift amount to increase the flow velocity and perform such homogenous mixing in a relatively short time. Further, as shown in FIG. 7, it is possible to increase the flow rate while stirring using a tumble flow or swirl, and perform such homogenous mixing in a relatively short time. Such techniques may be combined as long as homogeneous mixing is performed quickly and stable combustion is achieved.

Further, in the ignition timing control unit 122B of the control means 122, the ignition timing control includes a start time control mode in which ignition is performed at a predetermined angle of BTDC (before top dead center) when the engine speed is equal to or lower than a predetermined idle speed, If the timing is greatly advanced or retarded, the internal combustion engine 1 is adversely affected. Therefore, the normal time control mode in which control is performed from a predetermined angle of BTDC (before top dead center) to a predetermined angle of ATDC (after top dead center) is provided. is there.
During idle operation, optimal control is performed by adding a correction according to the coolant temperature and intake pressure to the idle basic ignition timing determined by the engine speed. Except during idling, optimal control is performed by adding various corrections to the basic ignition timing determined by the intake pressure and engine speed.
This ignition timing is corrected according to the cooling water temperature, the water temperature correction is retarded as the cooling water temperature is high, the air temperature is corrected according to the intake air temperature, the intake air temperature correction is retarded as the intake air temperature is high, and the retarded angle is higher than normal. Knock control correction for detecting a knock level between a predetermined angle of BTDC (before the top dead center) to a predetermined angle of ATDC (after the top dead center) by the knock sensor 116 and performing a delay according to the knock level, constant Acceleration correction that retards when accelerating under conditions and prevents knocking.
Although the optimal ignition timing varies depending on various parameters, basically, as the engine speed increases and becomes higher, the ignition timing becomes more advanced than when the engine speed is low. Near this time, abnormal combustion due to self-ignition, that is, knocking does not occur. In addition, the timing may be set at an optimum place in consideration of the rotational inertia and the crank offset. In this embodiment, the ignition timing of the advance angle that becomes the knocking limit can be increased. By improving the knocking, the compression ratio of the internal combustion engine 1 can be increased, the selection range of the optimal ignition timing characteristic based on the engine speed and the engine load can be expanded, and the advance angle characteristic can be improved. A simple internal combustion engine 1 can be realized.

  The ignition timing control is corrected in accordance with fluctuations in the engine speed during idle operation. The engine is advanced when the engine speed decreases, and is retarded when the engine speed increases. Stabilization correction, fuel cut return correction that corrects to reduce fluctuations in engine speed when returning from fuel cut, torque reduction request correction that suppresses shift shock by reducing engine torque by retarding during gear shifting, Etc. may be included.

  As shown in FIG. 8, the control means 122 performs duty control on the solenoid 93 of the hydraulic control valve 85 of the variable valve mechanism 83, and includes a crank angle sensor 110, a cam angle sensor 111, a water temperature sensor 115, and a throttle sensor 117. An actual valve timing determination unit 122C and a target advance amount setting unit 122D are provided in communication with the intake pressure sensor 119.

Next, the operation of this embodiment will be described based on the flowchart of FIG.
As shown in FIG. 1, when the program is started in the control means 122 (step A01), first, the engine speed, intake pressure, intake air amount, etc., which are output signals from various sensors are read (step A02), and the engine speed is read. The fuel injection period (fuel injection amount) is calculated from the engine operating conditions such as the number and engine load (step A03).
Further, the calculated fuel injection period, engine speed, intake pressure, intake air amount, etc. are read (step A04), and the number of divided injections is calculated from the calculated fuel injection period and engine operating conditions, and the division ratio is calculated. Calculate (step A05), thereby calculating the main injection period and the knock suppression injection period (step A06).
Then, the calculated main injection period, engine speed, intake pressure, intake air amount, etc. are read (step A07), the main injection timing is calculated from the engine operating conditions such as engine speed and engine load, and the beginning and end of the blow. Is determined (step A08).
Next, the knock suppression fuel amount is calculated based on the calculated knock suppression injection period and fuel pressure, the specifications of the fuel injection valve 69, etc., and the engine speed, intake pressure, intake air amount, intake air temperature, etc. are read (step A09). Further, the fuel vaporization period is calculated in consideration of the engine operating conditions (step A10).
Further, the calculated fuel vaporization period, the calculated knock suppression injection period, and the intake valve closing timing that changes depending on the engine operating conditions are read (step A12), the knock suppression injection timing is calculated, and the start and end of the blow are determined. (Step A12) and the program is returned (Step A13).
Therefore, the injection control is performed based on the calculated main injection period, main injection timing, knock suppression injection period, knock suppression injection timing, and fuel vaporization period.

Next, split injection in the fuel injection control of this embodiment will be described based on the time charts of FIGS.
As shown in FIG. 2, in the conventional fuel injection control, the injection is performed in the single injection period L during the intake stroke during the intake valve opening period. In the fuel injection control of this embodiment, first, The injection is performed only in the main injection period E as the first injection of the divided injection, and then after a certain time S, the end of fuel vaporization is delayed by the D period from the intake valve closing timing (bottom dead center (BDC: -180 deg)). In accordance with the angle P), that is, in consideration of the fuel evaporation time, as a late injection of the divided injection, the injection is performed in a predetermined knock suppression injection period F and is continuously performed in this knock suppression injection period F. Split injection is performed in the fuel vaporization period G. The intake valve closing timing P is a boundary between the intake stroke and the compression stroke. The ignition Q is performed at top dead center (TDC). The main injection period E is shorter than the conventional injection period L. The late injection period including the knock suppression injection period F and the fuel vaporization period G is substantially the same as the main injection period E, and the knock suppression injection period F is slightly longer than the fuel vaporization period G.
That is, there are many ideas using fuel vaporization heat regarding control for suppressing knocking by split injection, but in this embodiment, the idea of the control reference point is different.
For example, in the control in which the fuel is directly irradiated during the compression stroke, the effect of suppressing the knocking using the fuel vaporization heat is high, but the following problems are also concerned.
(1) Since the temperature environment and the flow of fuel in the combustion chamber 8 differ depending on the engine operating conditions, the time for generating the air-fuel mixture changes after the fuel evaporates.
(2) If the injection timing is delayed and the fuel evaporation time is insufficient due to fuel injection during the compression stroke, etc., the mixture distribution is likely to be shaded, and conversely, knocking is likely to occur.
(3) As the injection timing is retarded (the piston 7 moves up, the volume of the combustion chamber 8 decreases), the injected fuel collides with the piston 7 and smoke is likely to be generated.
(4) If the injection timing is set in advance by the engine speed or the like and the control is simplified, the above-mentioned problem becomes a problem, and when trying to execute accurate control, the parameters of the operating conditions become complicated, For example, the load on the control unit 122 increases.
(5) In actual operation, the fuel injection amount is changed due to variations in the specifications of the internal combustion engine 1 and the durability state, and the intake valve closing timing is changed from the performance aspect (actual compression ratio). The degree of occurrence of knocking changes due to the change in the number of times, and the optimal injection timing differs.
Therefore, in view of such problems, it is very difficult to uniformly control the fuel injection timing in accordance with the engine speed, the engine load, and the like. Therefore, in this embodiment, the intake valve closing timing P is used as a reference. The second injection timing is calculated from the injection amount at the injection ratio to avoid the above problem.

For example, as shown in FIG. 3, when the engine speed is 2000 rpm and full load, the intake valve closing timing P1 coincides with the bottom dead center (BDC: -180 deg), and knocking is severe. I want to increase the injection rate. The intake valve closing timing P1 is a boundary between the intake stroke and the compression stroke. The ignition Q1 is performed after top dead center (ATDC). Therefore, the ignition timing is retarded.
However, under these operating conditions,
(1) Since the temperature condition is lower than that at high rotation, the evaporation time becomes longer.
(2) Since the moving speed of the piston 7 is low, the flow of fuel in the combustion chamber 8 is small, and in the injection at a late time, there is an adverse effect of increased smoke and deterioration of the air-fuel mixture homogeneity.
Thus, in this embodiment, the intake valve closing timing P1 is advanced (lower volumetric efficiency) at a low engine speed, and the intake valve closing timing P1 is used as a control reference so that a desired divided injection is performed. And avoid the above problems.
Here, the divided injection ratio is set in advance based on the engine speed, the engine load, and the like. The fuel injection amount varies depending on various factors (variation, durability, knock control, etc.).
The flow of these calculations is based on engine operating conditions.
(1) Read the fuel injection amount calculated from the engine speed,
(2) Read the division ratio calculated from the engine speed,
(3) The second injection amount is calculated from the fuel injection amount and the division ratio,
(4) The evaporation time is calculated from the calculated second injection amount and engine operating conditions,
(5) Based on the intake valve closing timing P2, the second injection start timing is calculated from the second injection amount and the evaporation time.
When the engine speed is 2000 rpm and full load, in the conventional fuel injection control, the injection is performed in the single injection period L1 during the intake stroke during the intake valve opening period. In the fuel injection control, first, the injection is performed only during the main injection period E1 as the first injection of the divided injection, and then after a certain time S1, the fuel evaporation time is taken into consideration and the predetermined injection is performed as the latter injection of the divided injection. Fuel injection is performed in the knock suppression injection period F1, and split injection is performed in the fuel vaporization period G1 that is continued to the knock suppression injection period F1. The main injection period E1 is shorter than the conventional injection period L1. The late injection period including the knock suppression injection period F1 and the fuel vaporization period G1 is considerably longer than the main injection period E1, and the knock suppression injection period F1 and the fuel vaporization period G1 are substantially the same. Thereby, the division | segmentation injection control at the time of low rotation full load can be implemented efficiently.

Further, as shown in FIG. 4, when the engine speed is 4000 rpm and full load, when the engine speed is increased by the variable valve mechanism 83, the intake valve closing timing P2 is constant from the bottom dead center (BDC: -180 deg). The D2 period is retarded, and the retarded intake valve closing timing P2 is used as a reference. The intake valve closing timing P2 is a boundary between the intake stroke and the compression stroke. The ignition Q2 is performed before top dead center (BTDC). Therefore, the ignition timing is advanced.
When the engine speed is 4000 rpm and full load, in the conventional fuel injection control, the injection is performed in the single injection period L2 during the intake stroke during the intake valve opening period. In the fuel injection control, first, the injection is performed only during the main injection period E2 as the first injection of the divided injection, and then after a certain time S2, the fuel evaporation time is taken into consideration, and the predetermined injection is performed as the latter injection of the divided injection. Fuel injection is performed in the knock suppression injection period F2, and split injection is performed in the fuel vaporization period G2 that is continued to the knock suppression injection period F2. The main injection period E2 is about half of the conventional injection period L2. The late injection period including the knock suppression injection period F2 and the fuel vaporization period G2 is slightly longer than the main injection period E2, and the knock suppression injection period F2 is slightly shorter than the fuel vaporization period G2. Thereby, the division | segmentation injection control at the time of medium rotation full load can be implemented efficiently.

Further, as shown in FIG. 5, when the engine speed is 6000 rpm and full load, when the engine speed is increased by the variable valve mechanism 83, the intake valve closing timing P3 changes from the bottom dead center (BDC: -180 deg) to the intake air. The angle is retarded by a fixed D3 period larger than the valve closing timing P2, and the retarded intake valve closing timing P3 is used as a reference. The intake valve closing timing P3 is a boundary between the intake stroke and the compression stroke. The ignition Q3 is performed before top dead center (BTDC) and before the ignition Q2 in FIG. Therefore, the ignition timing is further advanced.
When the engine speed is 6000 rpm and full load, in the conventional fuel injection control, the injection is performed in the single injection period L3 during the intake stroke during the intake valve opening period. In the fuel injection control, first, injection is performed only during the main injection period E3 as the first period injection of the divided injection, and then, after a certain time S3, the fuel evaporation time is taken into consideration, and as the second period injection of the divided injection, a predetermined injection is performed. Fuel injection is performed in the knock suppression injection period F3, and split injection is performed in the fuel vaporization period G3 that is continued to the knock suppression injection period F3. The main injection period E3 is slightly shorter than the conventional injection period L3. The late injection period including the knock suppression injection period F3 and the fuel vaporization period G3 is considerably shorter than the main injection period E3, and the knock suppression injection period F3 and the fuel vaporization period G3 are substantially the same. Thereby, the division | segmentation injection control at the time of high rotation full load can be implemented efficiently.
Then, although the intake valve closing timing P3 is delayed with respect to the crank angle, the ratio of split injection (second time) decreases because of the engine operating condition in which knocking is unlikely to occur. Further, since the evaporation time is shortened and the flow of fuel in the combustion chamber 8 is large, problems such as an increase in smoke do not occur even in the late injection. In this case, per half rotation of the crankshaft 10 is on the order of several ms (high rotation) to several tens of ms (low rotation).

In the relationship between the low rotation range shown in FIG. 3, the middle rotation range shown in FIG. 4, and the high rotation range shown in FIG. 5, the low rotation range shown in FIG. 3 includes the intake valve closing timing P1 and the bottom dead center (BDC). : -180 deg) coincides with each other, but when the variable valve mechanism 83 is operated, as shown in the middle rotation region of FIG. 4 and the high rotation region of FIG. It will be different from P2. Further, the evaporation time is calculated from the divided injection ratio and the injection amount calculated from the engine speed, and the second injection start timing is calculated based on the intake valve closing timing (changing timing).
That is, in the divided injection according to this embodiment, at the full load (WOT), the ignition timing is advanced as the engine speed increases, while the phase of the intake valve 19 is retarded. The crank angle corresponding to is narrow. Therefore, since the unit time per rotation of the engine speed is shortened, the required time is shortened. In the high rotation range, the bottom dead center has passed even in the intake stroke injection, and it takes about several ms from the late injection of the divided injection to the ignition, and the absolute fuel vaporization time is reduced (low rotation range). Then, since it is about several tens of ms, it is an order of several tens of times.
Here, as a condition where knocking is likely to occur, the entire load is exemplified, and a high load state in the vicinity of the load vicinity region is represented. The same tendency may be set for the medium load region, the low load region, or the medium rotation region and the low rotation region, thereby simplifying the control logic variation. In this case, since the number of control switching is reduced, control stability can be obtained. In addition, the fuel that promotes atomization can achieve homogeneous combustion and achieve both improvement in power performance and fuel efficiency.
Since there is no compression stroke injection, it is possible to construct an in-cylinder fuel injection system without increasing the fuel supply pressure or giving high pressure resistance to the fuel injection valve 69 facing the combustion chamber 8. It becomes. The cylinder head 4 can be made compact by a low-pressure system of fuel supply pressure.
Needless to say, the present invention can be applied to an excellent high-pressure system by atomizing the injected fuel and shortening the injection time.

Therefore, in this embodiment, the internal combustion engine 1 applies a mechanism for generating a fuel mixture by injecting the fuel necessary for the engine operating condition once or a plurality of times during the intake stroke or the compression stroke. The purpose of suppressing knocking can be achieved by positively utilizing the latent heat of vaporization of the fuel injected inside.
In other words, the required fuel injection period is divided into a plurality of times according to the engine operating conditions, and the homogeneous performance of the air-fuel mixture is improved during the main injection period, and the temperature of the air-fuel mixture is lowered by knock suppression injection that is subsequent injection. . The knock suppression injection period and the blow end timing are determined by the intake valve closing timing determined by the respective engine operating conditions and the fuel vaporization period that varies depending on the engine operating conditions and the injection amount, and the method is controlled. (See FIG. 2).
The knock suppression injection period and the blow end time are determined in consideration of the following points.
(1), intake valve closing timing that varies depending on variable valve mechanism 83 and operating conditions, etc. (2), fuel injection amount that varies depending on engine operating conditions (3), knock suppression injection period, that is, knock suppression fuel injection amount And the fuel vaporization period that changes according to engine operating conditions

Therefore, when the injection control according to this embodiment is compared with the injection control according to the technique of the above-mentioned patent document, the mixture temperature at the boundary time between the intake stroke and the compression stroke, that is, the compression start time that is the intake valve closing timing. In contrast, the rate of temperature increase (gradient) of the internal gas in the state where the compression process proceeds is also different, so the internal gas temperature at the maximum compression point or near the ignition timing will be different. There is a difference in the presence or absence.
Further, not only the temperature at the time of starting compression is varied, but also the temperature change accompanying the progress of compression may differ depending on the difference in the components and state of the internal gas in the combustion chamber 8.
At this time, a mist-like liquid (a liquid with a very fine particle size) is diffused non-uniformly in the main air, and the wall and bottom surface constituting the combustion chamber 8 and the air that is full Phase change (change from liquid phase to gas phase) is caused by the phase change due to heat conduction and sudden pressure change.
The difference in the timing of the divided injection is also the difference in time for these phase changes, and the ratio of these phase changes is different.
As a result, the injection control according to the technology of the above-mentioned patent document differs from the injection control according to this embodiment in that the temperature of the internal gas near the ignition timing is different even when the total fuel injection amount of the split injection is the same. It will be.
However, in this embodiment, with respect to a level where knocking does not occur, a low mixture temperature of the same level with a small amount of fuel by the late injection of the split injection during the intake stroke, or a low mixture temperature of a lower level with the equivalent fuel It can be done.

As a result, in this embodiment , the internal combustion engine 1 is provided with a variable valve mechanism 83 that changes the opening / closing timing of the intake valve 19, and the opening / closing timing of the intake valve 19 is advanced according to various conditions including artificial operation and emission conditions. The control means 122 is provided with a phase control function for changing and controlling the angle and retard. In addition, the control means 122 divides fuel injection during the opening period of the intake valve 19 to be changed, and completes the final fuel injection for a predetermined time before the closing timing of the intake valve 19. The predetermined time is set from the injection amount of the last divided injection in consideration of the time required for vaporizing the final injection amount (so as to be equivalent to the time).
As a result, the temperature of the air-fuel mixture can be lowered to the lowest at the start (immediately before) of the compression stroke, sufficient evaporation time can be provided, and knocking is suppressed by making maximum use of the heat of vaporization of the fuel. In addition, the possibility of the occurrence of smoke can be reduced, and control is performed even if various corrections are added to the fuel injection amount due to factors such as engine operating conditions, endurance changes, and variations. It becomes possible.
Further , the control means 122 changes the distribution between the injection amount in the first main injection and the injection amount in the last divided injection according to predetermined engine operating conditions including the engine speed and the engine load, with the number of divided injections being two. To do.
As a result, the engine operating condition parameter does not increase and the control means 122 is not overloaded.
Further , the control means 122 obtains the time required for vaporization of the final injection amount from the injection amount of the final divided injection determined by the distribution from the engine operating conditions, and the closing timing of the intake valve 19 that changes with the phase control Based on the above, control is performed to start the last fuel injection of the division.
Thus, the injection timing can be changed by starting retrospective injection of the divided injection retrospectively with the closing timing of the variable intake valve 19 as a reference (not fixed uniformly), and the change in the actual compression ratio can be changed. As a reference, an optimal injection timing can be set.

  The suppression of knocking by lowering the temperature of the air-fuel mixture in the combustion chamber can be applied to other internal combustion engines other than in-cylinder injection type internal combustion engines, and is also applicable to internal combustion engines that use various fuels such as gasoline and light oil. Can also be applied.

It is a flowchart of the injection control of an internal combustion engine. It is a time chart of injection control of an internal-combustion engine. It is a time chart of the injection control at the time of engine speed 2000rpm-full load. It is a time chart of the injection control at the time of engine speed 4000rpm-full load. It is a time chart of the injection control at the time of engine rotation speed 6000rpm-full load. It is a system block diagram of the control apparatus of an internal combustion engine. It is an expanded sectional view of an internal combustion engine. It is a system block diagram of a variable valve mechanism. It is a figure which shows the valve timing of a variable valve mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Control apparatus 6 Cylinder 8 Combustion chamber 17 Intake cam shaft 19 Intake valve 21 Exhaust cam shaft 23 Exhaust valve 37 Supercharger 57 Fuel supply device 68 Delivery pipe 69 Fuel injection valve 80 EGR device 83 Variable valve mechanism 84 Hydraulic actuator 85 Hydraulic control valve 110 Crank angle sensor 111 Cam angle sensor 112 Air flow meter 113 Fuel pressure sensor 115 Water temperature sensor 116 Knock sensor 117 Throttle sensor 119 Intake pressure sensor 120 Intake temperature sensor 121 Oxygen sensor 122 Control means

Claims (1)

Provided with a fuel supply device that can supply fuel directly into the combustion chamber of the internal combustion engine, controls the fuel injection amount according to various states including the internal state of the internal combustion engine, and divides the fuel injection into multiple times under predetermined conditions In a control apparatus for a direct injection internal combustion engine provided with a control means having a fuel injection function for performing control as described above, the internal combustion engine is provided with a variable valve mechanism for changing the opening / closing timing of the intake valve, The control means has a phase control function for changing and controlling the opening / closing timing to advance and retard according to various conditions including artificial operation and emission conditions, while the control means The fuel injection is divided during the valve opening period, and the final fuel injection is completed for a predetermined time before the closing timing of the intake valve, and the final injection amount is reduced. Control apparatus for a cylinder injection type internal combustion engine, characterized in that in consideration of setting the predetermined time from the injection amount of the final split injection time required for.

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