JP2022062413A - Control device of internal combustion engine - Google Patents

Abstract

To suppress deviation of an air-fuel ratio from a target air-fuel ratio.SOLUTION: Fuel injection from a low pressure fuel injection valve is started at an injection start timing of each cylinder set as a crank angle from a timing at which a piston of each cylinder is at an exhaust top dead center. The low pressure fuel injection valve is controlled so that the fuel injection from the low pressure fuel injection valve is continued over a fuel injection time based on fuel pressure in a low pressure supply pipe at the injection start timing and a target fuel injection amount. Furthermore, fuel pressure at the injection start timing is estimated using the injection start timing of each cylinder set as a crank angle from the timing at which a piston of a predetermined cylinder is at an exhaust top dead center.SELECTED DRAWING: Figure 5

Description

The present invention relates to a control device for an internal combustion engine, and more particularly, is used for an internal combustion engine device including an internal combustion engine having a low-pressure fuel injection valve and a high-pressure fuel injection valve, and a fuel supply device having a fuel pump and a high-pressure pump. Regarding the control device of the internal combustion engine.

Conventionally, as a control device for this type of internal combustion engine, a device used for an internal combustion engine device including an internal combustion engine, a fuel supply device, and a fuel pressure sensor has been proposed (see, for example, Patent Document 1). The internal combustion engine is configured as a V-type multi-cylinder internal combustion engine, and includes a low-pressure fuel injection valve (port injection valve) and a high-pressure fuel injection valve (in-cylinder injection valve). The fuel supply device connects the fuel pump (feed pump) that supplies the fuel in the fuel tank to the low pressure supply pipe (low pressure fuel pipe) connected to the low pressure fuel injection valve, and the fuel in the low pressure supply pipe to the high pressure fuel injection valve. It is equipped with a high-pressure pump (high-pressure fuel pump) that pumps to the high-pressure supply pipe. In this device, a pulsation damper is provided in the high-pressure pump, and the pulsation of the fuel pressure in the low-pressure supply pipe is suppressed by the pulsation damper.

Japanese Unexamined Patent Publication No. 2019-178662

In the above-mentioned fuel injection control device, a pulsation damper is provided in the high-pressure pump, but it is desired not to provide the pulsation damper in order to simplify the configuration. However, if the pulsation damper is not provided, the pulsation of the fuel pressure in the low pressure supply pipe cannot be suppressed. By the way, in the control of the low pressure fuel injection valve, the fuel pressure in the low pressure supply pipe is detected by the fuel pressure sensor, and the low pressure fuel injection valve is controlled by using the fuel injection time based on the detected fuel pressure from the fuel pressure sensor and the target fuel injection amount. .. If fuel pressure pulsation occurs in the low-pressure supply pipe, the difference between the fuel pressure detected by the fuel pressure sensor and the fuel pressure when actually performing fuel injection may become large, and the fuel injection time cannot be adjusted properly. , The difference between the fuel injection amount and the target fuel injection amount becomes large. As a result, the air-fuel ratio deviates significantly from the target air-fuel ratio.

The main purpose of the control device for an internal combustion engine of the present invention is to suppress deviation of the air-fuel ratio from the target air-fuel ratio.

The control device for the internal combustion engine of the present invention has adopted the following means in order to achieve the above-mentioned main object.

The control device for an internal combustion engine of the present invention
A multi-cylinder internal combustion engine with a low pressure fuel injection valve and a high pressure fuel injection valve,
The fuel in the fuel tank is supplied to the fuel pump connected to the low pressure fuel injection valve, and the fuel in the low pressure supply pipe is pressurized and supplied to the high pressure supply pipe connected to the high pressure fuel injection valve. A fuel supply device having a high-pressure pump that performs a pressurizing operation a number of times different from the number of cylinders during a period in which the crank shaft of the internal combustion engine makes two rotations.
A control device for an internal combustion engine that is used in an internal combustion engine device and controls the internal combustion engine.
Fuel injection from the low-pressure fuel injection valve is started at the injection start timing of each cylinder set as the crank angle from the timing when the piston of each cylinder becomes the exhaust top dead point, and in the low-pressure supply pipe at the injection start timing. The low-pressure fuel injection valve is controlled so that fuel injection from the low-pressure fuel injection valve is continued for a fuel injection time based on the fuel pressure and the target fuel injection amount.
In addition,
The gist is to estimate the fuel pressure at the injection start timing of each cylinder by using the injection start timing of each cylinder set as the crank angle from the timing when the piston of the predetermined cylinder becomes the exhaust top dead center. And.

In the control device of the internal combustion engine of the present invention, fuel injection from the low pressure fuel injection valve is started at the injection start timing of each cylinder set as the crank angle from the timing when the piston of each cylinder becomes the exhaust top dead point. The low-pressure fuel injection valve is controlled so that fuel injection from the low-pressure fuel injection valve is continued for a fuel injection time based on the fuel pressure in the low-pressure supply pipe and the target fuel injection amount at the injection start timing. Then, the fuel pressure at the injection start timing of each cylinder is estimated by using the injection start timing of each cylinder set as the crank angle from the timing when the piston of the predetermined cylinder becomes the exhaust top dead center. The high-pressure pump performs a pressurizing operation a number of times different from the number of cylinders during a period in which the crankshaft of the internal combustion engine makes two rotations. Therefore, depending on the cylinder, the phase of the fuel pressure pulsation at the injection start timing does not match the phase of the fuel pressure pulsation at the injection start timing of the other cylinders, and the fuel pressure at the injection start timing varies. In the control device of the internal combustion engine of the present invention, the fuel pressure at the injection start timing of each cylinder is estimated by using the injection start timing of each cylinder set as the crank angle from the timing when the piston of the predetermined cylinder becomes the exhaust top dead center. By doing so, even if the phase of the fuel pressure pulsation at the injection start timing of one cylinder does not match the phase of the fuel pressure pulsation at the injection start timing of another cylinder, the fuel pressure of the low pressure supply pipe at the injection start timing of all the cylinders. Can be estimated accurately. As a result, the deviation between the fuel injection amount and the target fuel injection amount due to the inability to properly adjust the fuel injection time is suppressed. As a result, deviation of the air-fuel ratio from the target air-fuel ratio can be suppressed.

It is a block diagram which shows the outline of the structure of the vehicle 10 which mounts the control device of the internal combustion engine as one Embodiment of this invention. It is a block diagram which shows the outline of the structure of the fuel supply device 50. It is a flowchart which shows an example of the fuel injection control routine for a port injection valve 25 executed in the common injection mode by an electronic control unit 70. An example of the relationship between the exhaust top dead center # 1TDC to # 6TDC of each cylinder, the injection start timings Ts (1) to (6), the fuel pressure fluctuation (fuel pressure pulsation) in the low pressure supply pipe 54, and the crank counter. It is explanatory drawing which shows. 5 is a flow chart showing an example of a fuel pressure estimation processing routine executed by the electronic control unit 70. It is explanatory drawing for demonstrating the amplitude A of the waveform of the fuel pressure fluctuation in a low pressure supply pipe 54, and the time B of a half cycle. It is explanatory drawing which shows an example of the relationship between the exhaust top dead center (# 1TDC to # 6TDC) of each cylinder, the estimated fuel pressure fluctuation ΔPest, the injection start timing Ts (1) to (6), and the crank counter.

Next, an embodiment for carrying out the present invention will be described with reference to examples.

FIG. 1 is a configuration diagram showing an outline of the configuration of a vehicle 10 equipped with a control device for an internal combustion engine as an embodiment of the present invention. As shown in the figure, the vehicle 10 of the embodiment shifts the power from the engine 12, the fuel supply device 50, and the engine 12 to the drive shaft DS connected to the drive wheel DW via the differential gear DF. It includes a transmission TM and an electronic control unit 70. The vehicle 10 may be configured as a hybrid vehicle having a motor in addition to the engine 12. The electronic control unit 70 corresponds to the "control device for an internal combustion engine" of the embodiment.

The engine 12 is configured as a multi-cylinder (six-cylinder in the example) internal combustion engine that outputs power using fuel such as gasoline or light oil. The engine 12 includes a port injection valve 25 for injecting fuel into an intake port (inside the intake pipe 23) and an in-cylinder injection valve 26 for injecting fuel into the cylinder (inside the combustion chamber 29) in each cylinder. The port injection valve 25 and the in-cylinder injection valve 26 have a built-in solenoid (not shown), and are configured as solenoid valves that open and close by turning on / off the energization of the solenoid. By providing the port injection valve 25 and the in-cylinder injection valve 26, the engine 12 can be operated in any one of the port injection mode, the in-cylinder injection mode, and the shared injection mode. In the embodiment, the engine 12 has 6 cylinders, but since it may be a multi-cylinder engine, it may be 8 cylinders, for example.

In the port injection mode, the air cleaned by the air cleaner 22 is sucked into the intake pipe 23 to pass through the throttle valve 24, and fuel is injected from the port injection valve 25 to mix the air and the fuel. Then, this air-fuel mixture is sucked into the combustion chamber 29 through the intake valve 28, and is explosively combusted by the electric spark of the spark plug 30. Then, the reciprocating motion of the piston 32 pushed down by the energy generated by the explosive combustion is converted into the rotational motion of the crankshaft 14. In the in-cylinder injection mode, air is sucked into the combustion chamber 29 as in the port injection mode, fuel is injected from the in-cylinder injection valve 26 in the middle of the intake stroke or after reaching the compression stroke, and the fuel explodes due to the electric spark by the spark plug 30. It is burned to obtain the rotational movement of the crankshaft 14. In the shared injection mode, when air is sucked into the combustion chamber 29, fuel is injected from the port injection valve 25, fuel is injected from the in-cylinder injection valve 26 in the intake stroke and the compression stroke, and the fuel explodes due to electric sparks from the spark plug 30. It is burned to obtain the rotational movement of the crankshaft 14. These injection modes are switched according to the operating state of the engine 12. The exhaust gas discharged from the combustion chamber 29 to the exhaust pipe 33 via the exhaust valve 31 is a purification catalyst (three elements) that purifies harmful components of carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). It is exhausted to the outside air through a purification device 34 having a catalyst). In the embodiment, the first cylinder # 1 to the sixth cylinder # 6 may be referred to in the order of igniting the six cylinders.

FIG. 2 is a configuration diagram showing an outline of the configuration of the fuel supply device 50. The fuel supply device 50 is configured as a device that supplies fuel in a fuel tank (not shown) to the port injection valve 25 and the in-cylinder injection valve 26 of the engine 12. The fuel supply device 50 includes a feed pump (fuel pump) 52, a low pressure supply pipe 54, a high pressure pump 56, and a high pressure supply pipe 58.

The feed pump 52 is configured as an electric pump that operates by being supplied with electric power from a battery (not shown), and is arranged in a fuel tank. The feed pump 52 supplies the fuel in the fuel tank to the low pressure supply pipe 54.

The low pressure supply pipe 54 is connected to the port injection valve 25 of each cylinder via the low pressure delivery pipe DL.

The high-pressure pump 56 is driven by power from the engine 12 (in the embodiment, rotation of the intake camshaft that opens and closes the intake valve 28), pressurizes the fuel in the low-pressure supply pipe 54, and supplies the fuel to the high-pressure supply pipe 58. It is configured as. The high-pressure pump 56 is connected to its suction port to open and close an electromagnetic valve when pressurizing fuel, and a check valve connected to its discharge port to regulate the backflow of fuel and hold the fuel pressure in the high-pressure supply pipe 58. And a plunger that operates (moves in the vertical direction in FIG. 1) by the rotation of the engine 12 (rotation of the intake camshaft). During the operation of the engine 12, the high pressure pump 56 sucks the fuel of the low pressure supply pipe 54 when the electromagnetic valve is opened, and checks the fuel compressed by the plunger when the electromagnetic valve is closed. The fuel supplied to the high-pressure supply pipe 58 is pressurized by intermittently feeding the fuel to the high-pressure supply pipe 58 via the valve. The high-pressure pump 56 performs a pressurizing operation a number of times (three times in the embodiment) different from the number of cylinders of the engine 12 (six in the embodiment) during the period in which the crankshaft 14 rotates twice. Due to such a pressurizing operation, pulsation is generated in the fuel pressure (fuel pressure) in the low pressure supply pipe 54 and the high pressure supply pipe 58. In the embodiment, since the high-pressure pump 56 performs the pressurizing operation three times in the period in which the crankshaft 14 makes two rotations, the waveform of the time change of the fuel pressure pulsation has three in the period in which the crankshaft 14 makes two rotations. The waveform has valleys and peaks. In the embodiment, the high-pressure pump 56 performs the pressurizing operation three times in the period in which the crankshaft 14 rotates twice, but the high-pressure pump 56 differs from the number of cylinders in the period in which the crankshaft 14 rotates twice. Since the pressurizing operation may be performed a number of times, for example, the high-pressure pump 56 may perform the pressurizing operation five times in a period in which the crankshaft 14 rotates twice.

The high-pressure supply pipe 58 is connected to the in-cylinder injection valve 26 of each cylinder via the high-pressure delivery pipe DH.

The electronic control unit 70 is configured as a microcomputer having a CPU, a ROM, a RAM, a flash memory, and an input / output port.

Signals from various sensors are input to the electronic control unit 70 via the input port. Among the signals input to the electronic control unit 70, the signals related to the engine 12 include, for example, the crank angle θcr from the crank position sensor 15 that detects the rotational position of the crankshaft 14 of the engine 12, and the cooling water of the engine 12. The water temperature Tw from the water temperature sensor 40 that detects the temperature of the above can be mentioned. Cam angles θci and θco from the cam position sensor 44 that detect the rotational position of the intake camshaft that opens and closes the intake valve 28 and the rotational position of the exhaust camshaft that opens and closes the exhaust valve 31 can also be mentioned. Throttle opening TH from the throttle position sensor 24a that detects the position of the throttle valve 24, intake air amount Qa from the air flow meter 23a attached to the intake pipe 23, and suction from the temperature sensor 23t attached to the intake pipe 23. The temperature Ta can also be mentioned. The air-fuel ratio AF from the air-fuel ratio sensor 35 installed on the upstream side of the purification device 34 of the exhaust pipe 33 and the oxygen signal O2 from the oxygen sensor 36 installed on the downstream side of the purification device 34 of the exhaust pipe 33 also. Can be mentioned.

Among the signals input to the electronic control unit 70, the signals related to the fuel supply device 50 include, for example, the rotation speed Nlp of the feed pump 52 from the state detection device (not shown) attached to the feed pump 52, and a battery (not shown). The operating current Ilp and the operating voltage Vlp supplied from the feed pump 52 to the feed pump 52 can be mentioned. Further, the low-pressure fuel pressure (pressure of the fuel in the low-pressure supply pipe 54) Pflo from the fuel pressure sensor 54a attached near the port injection valve 25 of the low-pressure supply pipe 54 (for example, the low-pressure delivery pipe DL), the cylinder of the high-pressure supply pipe 58. High-pressure fuel pressure (pressure of fuel in the high-pressure supply pipe 58) Pfhi from the fuel pressure sensor 58a attached near the inner injection valve 26 (for example, the high-pressure delivery pipe DH) can also be mentioned.

Among the signals input to the electronic control unit 70, signals other than those described above include, for example, a signal from the transmission TM and a vehicle speed V from the vehicle speed sensor 82. Although not shown, the ignition signal IG from the ignition switch, the shift position SP from the shift position sensor that detects the operation position of the shift lever, and the accelerator opening Acc from the accelerator position sensor that detects the amount of depression of the accelerator pedal. The brake position BP from the brake position sensor that detects the amount of depression of the brake pedal can also be mentioned.

Various control signals are output from the electronic control unit 70 via the output port. The signals output from the electronic control unit 70 include, for example, a control signal to the throttle valve 24 of the engine 12, a control signal to the port injection valve 25, a control signal to the in-cylinder injection valve 26, and a spark plug 30. A control signal can be mentioned. A control signal to the feed pump 52 of the fuel supply device 50 and a control signal to the solenoid valve of the high pressure pump 56 can also be mentioned. A control signal to the transmission TM can also be mentioned.

The electronic control unit 70 calculates the rotation speed Ne, the load factor KL, and the torque Te of the engine 12. The rotation speed Ne of the engine 12 is calculated based on the crank angle θcr from the crank position sensor 15. The load factor KL of the engine 12 is the ratio of the volume of air actually sucked in one cycle to the stroke volume per cycle of the engine 12, and the intake air amount Qa from the air flow meter 23a and the rotation speed Ne of the engine 12. It is calculated based on. The torque Te of the engine 12 is calculated (estimated) based on the throttle opening degree TH from the throttle position sensor 24a.

In the vehicle 10 of the embodiment configured in this way, the CPU of the electronic control unit 70 performs intake air amount control, fuel injection control, and ignition control of the engine 12 when the engine 12 is operated.

For the intake air amount control of the engine 12, for example, the target intake air amount Qa * is set based on the target load factor KL * of the engine 12 based on the accelerator opening Acc and the vehicle speed V, and the intake air amount Qa is the target intake air amount. This is performed by setting the target throttle opening TH * so as to be Qa * and controlling the throttle valve 24 using the target throttle opening TH *. The fuel injection control sets the execution injection mode from the port injection mode, the in-cylinder injection mode, and the shared injection mode based on the engine 12 rotation speed Ne and the load factor KL, and is based on the intake air amount Qa and the execution injection mode. The target fuel injection amounts Qfp * and Qfd * of the port injection valve 25 and the in-cylinder injection valve 26 are set so that the air-fuel ratio AF becomes the target air-fuel ratio AF * (for example, the theoretical air-fuel ratio), and the target fuel injection amount Qfp. This is performed by controlling the port injection valve 25 and the in-cylinder injection valve 26 using * and Qfd *. For ignition control, the target ignition timing Ti * is set based on the engine speed Ne and the target load factor KL *, and the set target ignition timing Ti * is used from the 1st cylinder 1 # to the 6th cylinder 6 #. It is performed by controlling the spark plug 30 of each cylinder so that ignition is performed in this order.

Next, the operation of the vehicle 10 provided with the fuel injection control device of the embodiment configured in this way, particularly the fuel injection control for the port injection valve 25 when the shared injection mode is set as the execution injection mode will be described. FIG. 3 is a flowchart showing an example of a fuel injection control routine for the port injection valve 25 executed by the electronic control unit 70 in the shared injection mode. This routine is repeatedly executed when the energization on command of the solenoid of the port injection valve 25 is given (when the injection start command for starting the fuel injection is given from the port injection valve 25).

When the fuel injection control routine is executed, the CPU of the electronic control unit 70 determines the engine 12 rotation speed (engine rotation speed) Ne, the target fuel injection amount Qfp *, and the fuel pressure Psest (1) to (6) at the start of estimation. Is executed (step S100). The rotation speed Ne is input calculated based on the crank angle θcr from the crank position sensor 15. As the target fuel injection amount Qfp *, the one set in the above process is input when the shared injection mode is set as the execution injection mode. The estimated start fuel pressure Psest (1) to (6) is a low-pressure supply pipe at the timing of starting fuel injection from the port injection valve 25 of each cylinder to the intake port (timing of starting energization of the solenoid of the port injection valve 25). As the estimated value of the fuel pressure in 54, the one set in the fuel pressure estimation process described later is input. The fuel pressure estimation process will be described later.

Next, the fuel injection times tinj (1) to (6) of each cylinder are set from the estimated start fuel pressures Psest (1) to (6) and the target fuel injection amount Qfp * (step S110), and the exhaust of each cylinder is exhausted. With reference to the timing of the top dead point TDC, energization of the solenoid of the port injection valve 25 of each cylinder so that fuel injection starts at the timing when a predetermined crank angle θref elapses from the crank angle (timing) that becomes the exhaust top dead point TDC. Is started, the port injection valve 25 of each cylinder is controlled so that fuel is injected into the intake port during the fuel injection time tinj (step S120), and the fuel injection control routine is terminated. The predetermined crank angle θref in step S130 is a predetermined angle as the crank angle from the exhaust top dead center TDC of each cylinder to the start of fuel injection of the cylinder. In the embodiment, the predetermined crank angle θref uses the same value for each cylinder.

FIG. 4 shows the exhaust top dead center # 1 TDC to # 6 TDC of each cylinder, the injection start timings Ts (1) to (6), the fuel pressure fluctuation (fuel pressure pulsation) in the low pressure supply pipe 54, and the crank counter. It is explanatory drawing which shows an example of a relationship. In the figure, in the waveform of the fuel pressure fluctuation, the fuel pressure fluctuation at the injection start timings Ts (1) to (6) is indicated by a black circle. As described above, the injection start timing Ts of each cylinder is set as iming after a predetermined crank angle θref has passed from the exhaust top dead center TDC of the cylinder. For example, in the first cylinder (# 1), fuel injection is started at the timing (injection start timing Ts (1)) when a predetermined crank angle θref has passed from the exhaust top dead center # 1 TDC of the first cylinder (# 1). In the second cylinder (# 2), fuel injection is started at the timing (injection start timing Ts (2)) when a predetermined crank angle θref has elapsed from the exhaust top dead center # 2 TDC of the second cylinder (# 2). By such processing, the injection start timings Ts (1) to (6) are determined by using the timing of the exhaust top dead center TDC of each cylinder and the predetermined crank angle θref. It is possible to suppress an increase in the calculation load as compared with the one to be calculated.

Next, the fuel pressure estimation process will be described. FIG. 5 is a flow chart showing an example of a fuel pressure estimation processing routine executed by the electronic control unit 70. The fuel pressure estimation processing routine is executed when the first cylinder 1 # reaches the compression top dead center # 1 TDC.

When the fuel pressure estimation processing routine is executed, the CPU of the electronic control unit 70 executes a process of inputting the low pressure fuel pressure Pflo (step S200). The low pressure fuel pressure Pflo inputs the detection value detected by the fuel pressure sensor 54a.

When the low-pressure fuel pressure Pflo is input in this way, the input low-pressure fuel pressure Pflo is stored in the RAM (step S210), and it is determined whether or not a half cycle of the time-varying waveform of the low-pressure fuel pressure Pflo has elapsed (step S220). When the half cycle of the time fluctuation of the low pressure fuel pressure Pflo has not elapsed, steps S200 to S220 are repeated until it elapses.

When the half cycle of the time fluctuation of the low pressure fuel pressure Pflo has elapsed in step S220, the amplitude A of the waveform of the time fluctuation of the low pressure fuel pressure Pflo for the half cycle stored in the RAM and the time B of the half cycle are used to crank. The relational expression between the angle θcr and the estimated value (estimated fuel pressure fluctuation) ΔPest of the fluctuation of the low pressure fuel pressure is derived from the following equation (1) (step S230). FIG. 6 is an explanatory diagram for explaining the amplitude A and the time B of the half cycle in the waveform of the fluctuation of the low pressure fuel pressure Pflo.

ΔPest (θcr) = A ・ cos2 (θcr-B) ・ ・ ・ (1)

After deriving the relational expression between the crank angle θcr and the estimated fuel pressure Pest, the crank angle θcr when the first cylinder 1 # reaches the compression top dead center # 1TDC is set to 0 ° (CA), and the above equation (1) and Estimated start fuel pressure as an estimated value of the fuel pressure in the low pressure supply pipe 54 when starting fuel injection in each cylinder based on the central fuel pressure Pc based on the low pressure fuel pressure Pflo (for example, the time average value of the low pressure fuel pressure Pflo). Psest (1) to (6) are calculated (step S240), and this routine is terminated.

FIG. 7 is an explanatory diagram showing an example of the relationship between the exhaust top dead center # 1TDC to # 6TDC of each cylinder, the estimated fuel pressure fluctuation ΔPest, the injection start timings Ts (1) to (6), and the crank counter. be. In the figure, in the waveform of the fuel pressure, the fuel pressure at the injection start timings Ts (1) to (6) is indicated by a black circle. By the way, when the high-pressure pump 56 performs the pressurizing operation the same number of times as the number of cylinders of the engine 12 during the period when the crankshaft 14 of the engine 12 makes two rotations, the phases of the fuel pressure fluctuations at the injection start timing match in all the cylinders. do. Therefore, the fuel pressure at the timing when a predetermined crank angle θref has elapsed from the exhaust top dead center TDC of one cylinder (for example, the first cylinder # 1) and the other cylinders (for example, the second cylinder # 2 to the sixth cylinder # 6). ) Will have the same fuel pressure at the injection start timing. Therefore, as long as the fuel pressure at the timing when a predetermined crank angle θref has elapsed from the exhaust top dead center TDC of one cylinder (for example, the first cylinder # 1) is calculated, it is used as the fuel pressure at the injection start timing of all the cylinders. Can be used. However, the high-pressure pump 56 performs three pressurizing operations different from the number of cylinders of the engine 12 during the period in which the crankshaft 14 of the engine 12 makes two rotations. Therefore, as shown in FIGS. 4 and 7, for example, the phases of the fuel pressure pulsations do not match between the injection start timing Ts (1) and the injection start timing Ts (2). Therefore, if the fuel pressure is estimated by the same method as when the high-pressure pump 56 performs the pressurizing operation the same number of times as the number of cylinders of the engine 12 during the period when the crankshaft 14 of the engine 12 makes two rotations, the actual low-pressure supply is supplied. The deviation between the fuel pressure in the pipe 54 and the estimated fuel pressure becomes large. In the embodiment, the first cylinder 1 # is compressed based on the relational expression between the crank angle θcr and the estimated fuel pressure fluctuation ΔPest derived by using the data for half a cycle of the time fluctuation of the low pressure fuel pressure Pflo actually detected. Since the estimated start fuel pressure Psest (1) to (6) are calculated based on the time when the top dead center # 1 TDC is reached (0 °), the fuel pressure at the start of fuel injection can be estimated accurately. As a result, the deviation between the actual fuel injection amount from the port injection valve 25 and the target fuel injection amount Qfp * due to the inability to properly adjust the fuel injection time tinj is suppressed. As a result, deviation from the target air-fuel ratio AF * of the air-fuel ratio AF can be suppressed.

Further, the first cylinder 1 # reaches the compression top dead center # 1 TDC based on the relational expression between the crank angle θcr and the estimated fuel pressure fluctuation ΔPest derived by using the data for half a cycle of the time fluctuation of the low pressure fuel pressure Pflo. Since the estimated start fuel pressure Psest (1) to (6) is calculated based on the time when the injection start timing Ts (1) to (6) is approaching, the fuel injection is started. The fuel pressure can be estimated more accurately by a simpler method than the one that estimates the fuel pressure at the time. Therefore, it is possible to suppress an increase in the calculation load in the electronic control unit 70.

According to the vehicle 10 provided with the control device for the internal combustion engine of the above-described embodiment, the injection start timing Ts (1) of each cylinder is set as the crank angle from the timing when the piston 32 of each cylinder becomes the exhaust top dead point TDC. )-(6), fuel injection from the port injection valve 25 (low-pressure fuel injection valve) is started, and the estimated start fuel pressure Psest (1)-(6) in the low-pressure supply pipe 54 and the target fuel injection amount Qfp * The port injection valve 25 is controlled so that the fuel injection from the port injection valve 25 is continued over the fuel injection time tinj (1) to (6) based on the above, and the piston 32 of the first cylinder # 1 is exhausted. By estimating the fuel pressure in the low pressure supply pipe 54 at the injection start timing of each cylinder using the injection start timings Ts (1) to (6) set as the crank angle from the timing when the top dead point TDC is reached, the fuel pressure in the low pressure supply pipe 54 is estimated. It is possible to suppress the deviation of the air fuel ratio AF from the target air fuel ratio AF *.

In the vehicle 10 provided with the control device for the internal combustion engine of the embodiment, the estimated start fuel pressure Psest (Pest) of each cylinder is based on the timing when the piston 32 of the first cylinder # 1 of the n cylinders becomes the exhaust top dead center TDC. 1) to Psest (6) (fuel pressure in the low pressure supply pipe 54 at the injection start timings Ts (1) to (6)) are estimated. However, since the timing at which the piston 32 of any of the n cylinders reaches the exhaust top dead center TDC may be used as a reference, for example, the piston 32 of the second cylinder # 2 becomes the exhaust top dead center TDC. The fuel pressures Psest (1) to Psest (6) at the start of estimation of each cylinder may be estimated based on the timing.

In the vehicle 10 provided with the control device for the internal combustion engine of the embodiment, the engine 12 includes a port injection valve 25 and an in-cylinder injection valve 26. However, the engine 12 may be provided with two types of fuel injection valves (low pressure fuel injection valve and high pressure fuel injection valve) to which fuels having different pressures are supplied.

In the embodiment, a case where the control device of the internal combustion engine of the present invention is applied to the vehicle 10 is illustrated. However, the control device for an internal combustion engine of the present invention is used for an internal combustion engine device including an engine having a low pressure fuel injection valve and a high pressure fuel injection valve, and a fuel supply device having a fuel pump and a high pressure pump. If so, it may be applied to anything.

The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem will be described. In the embodiment, the electronic control unit 70 corresponds to the "control device for an internal combustion engine".

As for the correspondence between the main elements of the examples and the main elements of the invention described in the column of means for solving the problem, the invention described in the column of means for solving the problems of the examples is carried out. Since it is an example for specifically explaining the form for solving the problem, the elements of the invention described in the column of means for solving the problem are not limited. That is, the interpretation of the invention described in the column of means for solving the problem should be performed based on the description in the column, and the examples are the inventions described in the column of means for solving the problem. It is just a concrete example.

Although the embodiments for carrying out the present invention have been described above with reference to the embodiments, the present invention is not limited to these embodiments and may be in various embodiments within the scope of the gist of the present invention. Of course it can be done.

The present invention can be used in the manufacturing industry of a control device for an internal combustion engine and the like.

10 vehicle, 12 engine, 14 crank shaft, 15 crank position sensor, 22 air cleaner, 23 intake pipe, 23a air flow meter, 23t temperature sensor, 24 throttle valve, 24a throttle position sensor, 25 port injection valve, 26 in-cylinder injection valve, 28 intake valve, 29 combustion chamber, 30 ignition plug, 31 exhaust valve, 32 piston, 33 exhaust pipe, 34 purification device, 35 air fuel ratio sensor, 36 oxygen sensor, 40 water temperature sensor, 44 cam position sensor, 50 fuel supply device, 52 feed pump, 54 low pressure supply pipe, 54a, 58a fuel pressure sensor, 56 high pressure pump, 58 high pressure supply pipe, 70 electronic control unit, 82 vehicle speed sensor, DF differential gear, DS drive shaft, DW drive wheel, TM transmission.

Claims (1)

A multi-cylinder internal combustion engine with a low pressure fuel injection valve and a high pressure fuel injection valve,
The fuel in the fuel tank is supplied to the fuel pump connected to the low pressure fuel injection valve, and the fuel in the low pressure supply pipe is pressurized and supplied to the high pressure supply pipe connected to the high pressure fuel injection valve. A fuel supply device having a high-pressure pump that performs a pressurizing operation a number of times different from the number of cylinders during a period in which the crank shaft of the internal combustion engine makes two rotations.
A control device for an internal combustion engine that is used in an internal combustion engine device and controls the internal combustion engine.
Fuel injection from the low-pressure fuel injection valve is started at the injection start timing of each cylinder set as the crank angle from the timing when the piston of each cylinder becomes the exhaust top dead point, and in the low-pressure supply pipe at the injection start timing. The low-pressure fuel injection valve is controlled so that fuel injection from the low-pressure fuel injection valve is continued for a fuel injection time based on the fuel pressure and the target fuel injection amount.
In addition,
A control device for an internal combustion engine that estimates the fuel pressure at the injection start timing by using the injection start timing of each cylinder set as the crank angle from the timing when the piston of the predetermined cylinder becomes the exhaust top dead center.

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