JP2009046995A - Control system of variable valve train of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for restraining the occurrence of a response delay in VVT control by a load of a high pressure fuel pump, in a VVT mechanism of an internal combustion engine for driving the high pressure fuel pump by a camshaft. <P>SOLUTION: This control system has the camshaft for driving an engine valve for opening-closing, the VVT mechanism capable of varying the valve timing by varying a rotational phase of the camshaft to a rotational phase of a crankshaft, a control means for executing the VVT control for changing the valve timing to the predetermined target valve timing by driving the VVT mechanism, a fuel injection valve, a pressurizing means for pressurizing fuel supplied to the fuel injection valve by driving force of the camshaft, and a correcting means for correcting a change speed in the valve timing by the VVT control based on a calculated load by calculating the load applied to the camshaft for driving the pressurizing means based on at least a fuel injection quantity by the fuel injection valve and pressure of the fuel pressurized by the pressurizing means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control system for a variable valve mechanism of an internal combustion engine.

  2. Description of the Related Art An internal combustion engine that includes a variable valve mechanism that varies the operating characteristics of a valve system of the internal combustion engine is known. The operating characteristics of the valve operating system mean the valve operating angle, valve lift amount (valve opening amount), and valve timing of the intake and exhaust valves. In an internal combustion engine equipped with a variable valve mechanism, the internal combustion engine is optimally changed in accordance with the operating state of the internal combustion engine by changing the valve operating angle, the valve lift amount, and the valve timing advance angle or delay angle according to the operating state of the internal combustion engine. Performance such as output, fuel consumption, exhaust emission, and idle stability can be improved.

For example, a technique relating to an internal combustion engine having a variable valve timing (VVT) mechanism for advancing or retarding the valve timing by advancing or retarding the rotational phase of the camshaft relative to the rotational phase of the crankshaft is disclosed. There exists patent document 1 as a literature.
JP 2003-172160 A

  By the way, in the cylinder injection engine, the camshaft not only drives the intake valve and the exhaust valve, but also high pressure fuel for pumping the fuel in the fuel tank to the fuel injection valve for injecting fuel into the cylinder at a high pressure. The pump may also be configured to drive. In such a configuration, since the load for driving the high-pressure fuel pump is applied to the camshaft, the speed of change of the rotational phase of the camshaft by the VVT mechanism is slowed by this load, and a response delay may occur in VVT control. . In this case, particularly in a transient operation state in which the target valve timing changes, there is a problem that an appropriate valve timing is not realized due to a delay in response of VVT control, and exhaust emission and drivability deteriorate.

  In response to this problem, according to the prior art described in Patent Document 1, according to the engine speed, the engine load, the coolant temperature, the hydraulic oil temperature of the hydraulic actuator that drives the VVT mechanism, the fuel injection amount, etc. The load of the high-pressure fuel pump is estimated, and the response speed of VVT control is corrected.

  By the way, the load of the high-pressure fuel pump is greatly influenced by the fuel pressure (fuel pressure). The influence of the fuel pressure on the load of the high-pressure fuel pump may be difficult to estimate based on the simple correlation between the fuel injection amount and other physical quantities described above. In the above prior art, since the fuel pressure is not taken into consideration, there is a possibility that the response delay of the VVT control cannot be sufficiently eliminated.

  The present invention has been made in view of such problems, and provides a technology that enables variable control of valve timing by the VVT mechanism to be executed with good responsiveness even in an internal combustion engine in which a high-pressure fuel pump is driven by a camshaft. The purpose is to do.

In order to achieve the above object, a control system for a variable valve mechanism of an internal combustion engine of the present invention includes:
A camshaft for opening and closing an engine valve of an internal combustion engine;
A VVT mechanism that makes the valve timing of the engine valve variable by making the rotational phase of the camshaft variable with respect to the rotational phase of the crankshaft of the internal combustion engine;
Control means for driving the VVT mechanism to perform VVT control for changing the valve timing of the engine valve to a predetermined target valve timing;
A fuel injection valve for injecting fuel into the internal combustion engine;
Pressurizing means for pressurizing the fuel supplied to the fuel injection valve by the driving force of the camshaft;
Load calculating means for calculating a load applied to the camshaft to drive the pressurizing means based at least on the fuel injection amount by the fuel injection valve and the pressure of the fuel pressurized by the pressurizing means;
Correction means for correcting the change rate of the valve timing by the VVT control based on the load calculated by the load calculation means;
It is characterized by providing.

  The load applied to the camshaft for driving the pressurizing means mainly depends on the fuel injection amount by the fuel injection valve and the pressure of the fuel pressurized by the pressurizing means (hereinafter also referred to as “fuel pressure”). Is determined. Specifically, the load on the camshaft tends to increase as the fuel injection amount increases and the fuel pressure increases. Therefore, the load applied to the camshaft can be accurately calculated based on at least the fuel injection amount and the fuel pressure.

  As described above, as the load applied to the camshaft increases, the valve timing change speed by the VVT control tends to decrease, and the response of the valve timing change by the VVT control tends to be delayed. On the other hand, according to the present invention, the change rate of the valve timing by the VVT control is corrected based on the load applied to the camshaft calculated by the load calculating means. Specifically, the change speed when the control means drives the VVT mechanism to change the valve timing toward the target valve timing is corrected. For example, the greater the load on the camshaft, the faster the valve timing change rate by VVT control. By doing so, even in an internal combustion engine configured such that a load for driving the pressurizing means is applied to the camshaft, a response delay in VVT control due to the load can be suppressed. Therefore, even in a transient operation state in which the target valve timing changes, the valve timing can be controlled with good responsiveness to the target valve timing, and deterioration of exhaust emission and drivability in the transient operation state can be suppressed.

  In the present invention, the response delay of the VVT control due to the load applied to the camshaft for driving the pressurizing means is calculated based on the load calculated by the load calculating means, and the calculated response delay is corrected. As described above, the change speed of the valve timing by the VVT control may be increased.

  According to the load calculation means of the present invention, the load applied to the camshaft can be accurately calculated based on the fuel injection amount and the fuel pressure. Therefore, the response delay of the VVT control is based on the load thus calculated. Can also be calculated with high accuracy. Therefore, if the change rate of the valve timing by the VVT control is increased so as to correct the response delay calculated in this way, the response delay of the VVT control due to the load on the camshaft can be suppressed more preferably. Can do.

  For example, the change rate of the valve timing by the VVT control may be increased by an amount corresponding to the calculated response delay, or when the calculated response delay exceeds a predetermined allowable limit, the predetermined speed A correction that increases the speed of change of the valve timing by the VVT control is also conceivable.

Here, when the VVT mechanism is a mechanism driven by a hydraulic actuator, the response delay of the VVT control due to the load applied to the camshaft to drive the pressurizing means is considered in consideration of the oil temperature of the hydraulic oil of the hydraulic actuator. It may be calculated as follows. The driving force of the VVT mechanism by the hydraulic actuator increases as the hydraulic pressure increases. The hydraulic pressure increases as the temperature of the hydraulic oil of the hydraulic actuator decreases. Therefore, when the oil temperature is low, the driving force of the VVT mechanism by the hydraulic actuator is larger than that when the oil temperature is high, and therefore the degree of response delay of VVT control due to the load on the camshaft tends to be small. is there. Thus, in order to calculate the response delay of the VVT control, the response delay of the VVT control can be calculated more accurately by considering the oil temperature of the hydraulic actuator hydraulic fluid in addition to the load applied to the camshaft. Will be able to. Therefore, it is possible to correct the change speed of the valve timing by the VVT control with higher accuracy.

  As a correction of the valve timing change speed by the VVT control in consideration of the oil temperature, for example, the response delay of the VVT control due to the load applied to the camshaft calculated by the load calculation means is reduced, and the improvement of the response delay due to the low oil temperature is reduced. Correction may be made in consideration, and the change speed of the valve timing by the VVT control may be increased by the correction means by an amount corresponding to the response delay corrected in consideration of the oil temperature. By doing so, it is possible to suppress an excessive increase in the change speed of the valve timing after correction under the low oil temperature condition.

  In the above description, as specific means for realizing “increase in valve timing change speed by VVT control” by the correction means, for example, in a configuration including a VVT mechanism driven by a hydraulic actuator, the supply to the hydraulic actuator It can be exemplified to increase the amount of hydraulic fluid that is produced. Further, the hydraulic pressure supplied to the hydraulic actuator may be increased. Further, auxiliary means for assisting the drive of the camshaft by the VVT mechanism may be further provided, and the assisting means may assist the drive of the camshaft by the VVT mechanism. Examples of the auxiliary means include a device that assists driving of the camshaft by an electric motor in a configuration including a VVT mechanism driven by a hydraulic actuator.

  As described above, the load applied to the camshaft tends to increase as the fuel injection amount increases and the fuel pressure increases. Further, the fuel injection amount and the fuel pressure increase as the required torque of the internal combustion engine increases. Therefore, when the internal combustion engine is in the acceleration transient operation state, the response delay of the VVT control due to the load applied to the camshaft tends to become remarkable. For example, when the response of the VVT control is delayed in an acceleration transient state in which the positive overlap amount increases as compared with the current operation state, the increase in the positive overlap is not in time, and the cylinder There is a possibility that the amount of intake air is insufficient. In that case, sufficient acceleration cannot be obtained and drivability deteriorates.

  Therefore, in the present invention, when the acceleration transient state occurs, the VVT control for changing the valve timing of the engine valve to the target valve timing corresponding to the operating state after acceleration is performed, and the fuel injection amount and fuel pressure after acceleration are increased. You may make it perform prior to the control changed toward each target value corresponding to a driving | running state. By doing this, the load applied to the camshaft increases due to the increase in the fuel injection amount and the fuel pressure, and thus the VVT control in accordance with the acceleration transient state is executed before the response speed of the VVT control decreases. It is possible to suppress the occurrence of response delay in VVT control. Accordingly, it is possible to more reliably suppress the deterioration of drivability in the acceleration transient state.

  The elements described above can be combined as much as possible to constitute the present invention.

According to the present invention, the fuel injection valve is provided with a VVT mechanism that makes the valve timing variable by making the rotational phase of the camshaft variable with respect to the rotational phase of the crankshaft, and the driving force of the camshaft driven by the VVT mechanism. In the internal combustion engine provided with the pressurizing means for pressurizing the fuel supplied to the engine, it is possible to suppress a delay in response of the VVT control due to the load of the pressurizing means.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the invention to those unless otherwise specified.

  FIG. 1 is a conceptual diagram showing a schematic configuration of a control system for an internal combustion engine according to the present embodiment.

  An internal combustion engine 1 shown in FIG. 1 is a diesel engine having a plurality of cylinders 2. A piston 15 is slidably inserted into the cylinder 2. A combustion chamber 23 is formed in the cylinder 2 by being partitioned by the piston 15 and the inner wall of the cylinder 2. A fuel injection valve 5 that directly injects fuel into the combustion chamber 23 is provided at the upper portion of the cylinder 2. Fuel is supplied to the fuel injection valve 5 from the common rail 72. Fuel in a fuel tank (not shown) is supplied to the common rail 72 by being pressurized to a high pressure by a high pressure fuel pump 68. The piston 15 is connected to the crankshaft 17 via a connecting rod 16. The internal combustion engine 1 is provided with a rotation speed sensor 18 that measures the rotation angle of the crankshaft 17. The output of the rotational speed sensor 18 is input to an ECU 20 described later, and the engine rotational speed of the internal combustion engine 1 is detected based on the output. The combustion chamber 23 communicates with the intake passage 30 via the intake port 3. Further, it communicates with the exhaust passage 40 through the exhaust port 4. The intake port 3 is opened and closed by an intake valve 10, and the intake valve 10 is driven in conjunction with the rotation of the intake camshaft 12. The exhaust port 4 is opened and closed by an exhaust valve 11, and the exhaust valve 11 is driven in conjunction with the rotation of the exhaust camshaft 13. In the internal combustion engine 1 of the present embodiment, the high-pressure fuel pump 68 is configured to be driven by the driving force of the intake camshaft 12. The high-pressure fuel pump 68 of this embodiment corresponds to the pressurizing means in the present invention.

  The internal combustion engine 1 of the present embodiment is provided with a variable valve timing mechanism (hereinafter referred to as “VVT mechanism”) 66 that makes the rotational phase of the intake camshaft 12 variable with respect to the rotational phase of the crankshaft 17. The VVT mechanism 66 of this embodiment is a mechanism driven by hydraulic pressure. The hydraulic fluid that drives the VVT mechanism 66 is discharged from a hydraulic control valve (hereinafter referred to as “OCV”) 70 and supplied to the VVT mechanism 66. The OCV 70 is supplied with hydraulic oil from an engine oil pan (not shown) by an oil pump (not shown). The VVT mechanism 66 of the present embodiment is an example of a VVT mechanism that is driven by a hydraulic actuator according to the present invention. By controlling the hydraulic pressure supplied to the VVT mechanism 66 by the OCV 70, the rotational phase of the intake camshaft 12 is changed with respect to the rotational phase of the crankshaft 17, thereby variably controlling the valve timing of the intake valve 10. .

  The internal combustion engine 1 configured as described above includes an ECU 20 that controls the operating state of the internal combustion engine 1. The ECU 20 is an electronic control computer that includes a CPU, a ROM, a RAM, and the like. In addition to the rotation speed sensor 18 described above, the ECU 20 includes a cam position sensor 74 that detects the rotation angle of the intake camshaft 12, a water temperature sensor 19 that measures the cooling water temperature of the internal combustion engine 1, and a depression amount of an accelerator pedal (not shown). The output of various sensors such as an accelerator opening sensor 22 that detects the accelerator opening and a fuel pressure sensor 75 that detects a fuel pressure in the common rail 72 (hereinafter referred to as “fuel pressure”) are input. In addition, the ECU 20 is connected to the fuel injection valve 5 and the OCV 70 as described above, and various devices are controlled by control signals output from the ECU 20 based on data input from the sensors. The

  The ECU 20 calculates the current valve timing of the intake valve 10 based on outputs from the rotation speed sensor 18 and the cam position sensor 74. Further, the operating state of the internal combustion engine 1 is detected based on the outputs of the rotation speed sensor 18, the accelerator opening sensor 22, the water temperature sensor 19 and other various sensors, and the target valve timing corresponding to the detected operating state is stored in advance. Read from the map. Then, the OCV 70 is controlled so as to drive the VVT mechanism 66 so that the valve timing of the intake valve 10 becomes the target valve timing. Hereinafter, the variable control of the valve timing of the intake valve 10 performed by the ECU 20 is referred to as “VVT control”.

  By the way, in the configuration in which the high pressure fuel pump 68 that pressurizes the fuel is driven by the driving force of the intake camshaft 12 as in the present embodiment, a load for driving the high pressure fuel pump 68 is applied to the intake camshaft 12, This load changes the response speed of the VVT control. In particular, in a diesel engine equipped with a common rail system as in the present embodiment, the load for driving the high pressure fuel pump 68 to supply the high pressure fuel to the common rail 72 is very large compared to a gasoline engine. There is a tendency that the response delay of the VVT control due to the load of 68 appears remarkably.

  Due to the delay in the response of the VVT control, the following problems may occur particularly in the transient operation state of the internal combustion engine 1. For example, the base valve timing with less valve overlap is set as the target valve timing in the middle load range, and the target valve timing is expanded in the light load range and high load range compared to the base valve timing. Consider a system that sets and performs VVT control. In such a system, when transient from light load to medium load, if the decrease in positive overlap is delayed due to the response delay of VVT control, the amount of internal EGR becomes transiently excessive and smoke increases. May occur. In addition, during a transition from a medium load to a high load, if the increase in positive overlap is delayed due to a response delay in VVT control, the in-cylinder intake air amount becomes transiently insufficient, and good acceleration performance cannot be obtained. May occur.

  To solve this problem, it is conceivable to estimate the load of the high-pressure fuel pump 68 according to the fuel injection amount and to correct the response delay of the VVT control accordingly. However, the load of the high-pressure fuel pump 68 is greatly influenced not only by the fuel injection amount but also by the fuel pressure. The influence of the fuel pressure on the load of the high-pressure fuel pump 68 may be difficult to estimate based on a simple correlation with the fuel injection amount. For example, when the in-cylinder pressure decreases during high altitude travel, there is a possibility that the amount of HC discharged increases due to excessive spraying. Therefore, fuel pressure control may be performed to lower the fuel pressure compared to when traveling on flat ground. In addition, when accelerating transiently, smoke filling is likely to occur due to delays in filling the cylinder and scavenging EGR gas compared to during steady operation, so fuel pressure control is performed to increase fuel pressure to improve atomization. There is. In addition, fuel pressure control according to the demand for penetrating force control of the injected fuel, fuel pressure control according to the atomization characteristics of the injected fuel, fuel pressure control corresponding to air mixing into the fuel in the common rail, according to the fuel temperature at engine start When controlling fuel pressure positively, such as fuel pressure control and fuel pressure control to cope with fuel leakage from the fuel injection valve after the engine is stopped, the load on the high-pressure fuel pump 68 for executing these fuel pressure controls is considered. However, in the system that estimates the load of the high-pressure fuel pump 68, the response delay of the VVT control may not be sufficiently corrected.

In this respect, in the system of this embodiment, the response delay of the VVT control due to the load of the high-pressure fuel pump 68 is calculated based on at least the fuel injection amount and the fuel pressure, and the response speed of the VVT control is corrected to correct the calculated response delay. Was increased. Further, paying attention to the fact that the response speed of the VVT control depends on the hydraulic pressure supplied to the VVT mechanism 66, the response delay of the VVT control calculated based on the fuel injection amount and the fuel pressure is corrected based on the hydraulic pressure. And more optimal response delay can be calculated.

  Here, processing contents of a routine for executing the response speed correction control of the VVT control will be described. By executing this routine, the ECU 20 plays a role corresponding to load calculation means and correction means in the present invention. FIG. 2 is a flowchart showing a response speed correction control routine of the VVT control of this embodiment. This routine is executed by the ECU 20 when a request for executing the VVT control is made.

  First, when this routine is started, in step S101, the ECU 20 acquires the fuel pressure and the fuel injection amount. The fuel pressure may be an actual fuel pressure detected by the fuel pressure sensor 75, or may be a target fuel pressure output from the ECU 20 when the above-described fuel pressure control is executed.

  In step S102, the load applied to the intake camshaft 12 for driving the high-pressure fuel pump 68 is calculated based on the fuel pressure and the fuel injection amount acquired in step S101. The relationship between the fuel pressure and the fuel injection amount and the load of the high-pressure fuel pump 68 is obtained in advance through experiments, simulations, and the like. In this embodiment, the ECU 20 that executes step S102 corresponds to the load calculation means in the present invention.

  In step S103, the ECU 20 acquires the engine speed and the engine coolant temperature.

  In step S104, the ECU 20 calculates the engine oil pressure based on the engine speed and the engine coolant temperature acquired in step S103. The engine oil pressure is correlated with the oil temperature, and the oil pressure tends to increase as the oil temperature decreases. The oil temperature is correlated with the engine coolant temperature. The oil pressure is correlated with the engine speed, and the oil pressure tends to increase as the engine speed increases.

  In step S105, the ECU 20 calculates a response speed of the VVT control based on the load calculated in step S102 and the engine hydraulic pressure calculated in step S104. As described above, the greater the load applied to the camshaft 12, the slower the response speed of VVT control. On the other hand, the higher the hydraulic pressure supplied to the VVT mechanism 66, the faster the response speed of VVT control. By considering both the load applied to the intake camshaft 12 and the hydraulic pressure supplied from the OCV 70 to the VVT mechanism 66, the response speed of the VVT control can be accurately calculated. In this embodiment, the ECU 20 that executes step S105 corresponds to the response delay calculating means in the present invention.

  In step S106, the ECU 20 determines whether or not the response speed of the VVT control calculated in step S105 is slower than a predetermined target response speed. Here, the target response speed is determined in advance based on the lower limit value of the response speed of the VVT control that does not cause the above-described exhaust emission or drivability deterioration due to the response delay of the VVT control. If an affirmative determination is made in step S106, the ECU 20 proceeds to step S107. If a negative determination is made in step S106, the ECU 20 proceeds to step S108.

  In step S107, the ECU 20 performs correction for increasing the response speed of the VVT control. Specifically, the OCV 70 is controlled so that the amount of hydraulic oil supplied to the VVT mechanism 66 is increased from that during normal control without correction. As a result, the hydraulic pressure for driving the VVT mechanism 66 increases, and the response speed of the VVT control by the VVT mechanism 66 increases. In this embodiment, the ECU 20 that executes step S107 corresponds to the correcting means in the present invention.

  In step S108, the ECU 20 does not correct the response speed of the VVT control.

  In step S109, the ECU 20 executes control for driving the VVT mechanism 66 to change the valve timing of the intake valve 10 to the target valve timing.

  By executing the routine described above, the VVT control is performed at a satisfactory response speed that satisfies the target response speed even in a situation where a load is applied to the intake camshaft 12 such that the response speed of the VVT control falls below the target response speed. It becomes possible to execute. Therefore, the valve timing of the intake valve 10 can be suitably changed to the target valve timing corresponding to the operating state of the internal combustion engine 1 while suppressing the response delay. In particular, according to the present embodiment, the load due to the high-pressure fuel pump 68 applied to the intake camshaft 12, which is one of the main parameters that determine the response delay of the VVT control, is considered in consideration of both the fuel injection amount and the fuel pressure. Therefore, it is possible to calculate the response delay of the VVT control more accurately. In addition, since the response speed of the VVT control is calculated in consideration of the influence of the hydraulic pressure on the response speed of the VVT control, for example, in a state where the oil temperature is low and the hydraulic pressure supplied to the VVT mechanism 66 is high. Can reduce the correction range of the acceleration correction of the response speed of the VVT control. As a result, it is possible to prevent the response speed of the VVT control from being corrected to an excessively high response speed by the increase correction of the response speed of the VVT control. That is, according to the present embodiment, even when the intake camshaft 12 is loaded by the high-pressure fuel pump 68, the response speed of the VVT control can be corrected to the target response speed without excess or deficiency. Therefore, even in a transient state in which the target valve timing changes, it is possible to suppress the deterioration of smoke and the acceleration performance due to the delay in the change of the valve overlap as described above.

  In the above embodiment, the hydraulic pressure for driving the VVT mechanism 66 is increased by increasing the amount of hydraulic oil supplied from the OCV 70 to the VVT mechanism 66 in order to increase the response speed of the VVT control. The means for increasing the response speed of the VVT control is not limited to this. For example, a pump for pressurizing the hydraulic oil supplied to the VVT mechanism 66 is further provided, and when an affirmative determination is made in step S106, the hydraulic pressure supplied to the VVT mechanism 66 may be increased by driving this pump. good. Further, a mechanism for assisting the drive of the intake camshaft 12 by the VVT mechanism 66, for example, an electric motor for rotationally driving the intake camshaft 12, is further provided. If the determination in step S106 is affirmative, the electric motor is driven. Thus, the driving of the intake camshaft 12 by the VVT mechanism 66 may be assisted.

In addition, since the load due to the high-pressure fuel pump 68 tends to increase as the engine load increases, there is a possibility that the influence due to the response delay of the VVT control appears remarkably during acceleration transient. Therefore, during acceleration transition, VVT control for changing the valve timing of the intake valve 10 to the target valve timing may be executed prior to control for changing the fuel injection amount and the fuel pressure to the respective target values. Specifically, when an acceleration request is issued (for example, when the accelerator opening sensor 22 detects an increase in the accelerator pedal depression amount by a predetermined amount or more), a routine as shown in the flowchart of FIG. 3 is executed. It is made to execute by ECU20. First, in step S201, the ECU 20 executes VVT control. That is, the VVT mechanism 66 is driven to change the valve timing of the intake valve 10 to the target valve timing corresponding to the acceleration transient. Then, after executing Step S201, the ECU 20 executes control of the fuel injection amount and the fuel pressure. That is, the fuel injection amount is increased to the target fuel injection amount corresponding to the acceleration transient, and the fuel pressure is increased to the target fuel pressure corresponding to the acceleration transient. By executing this routine at the time of an acceleration request, as shown in FIG. 4, when the accelerator opening is increased at time t1 and an acceleration request is issued, VVT control is first executed at time t2 (> t1). As a result, the positive overlap amount increases at a desired response speed, the fuel injection amount and the fuel pressure are controlled at time t3 after time t2, and the fuel injection amount and fuel pressure increase. By executing this routine, VVT control can be executed before the response delay of VVT control due to increase in fuel injection amount and fuel pressure increases, so the positive overlap amount is increased at a good response speed. It is possible to suppress deterioration of acceleration performance.

  Each of the above-described embodiments is an example for explaining the present invention, and various modifications can be made to the above-described embodiments without departing from the spirit of the present invention. Further, the present invention can be implemented by combining the embodiments as much as possible. For example, in the present embodiment, the configuration in which the high-pressure fuel pump 68 is driven by the intake camshaft 12 has been described as an example. However, the present invention is similarly applied to the configuration in which the high-pressure fuel pump 68 is driven by the exhaust camshaft 13. Can do. In this embodiment, the example in which the present invention is applied to the configuration including the hydraulic drive type VVT mechanism 66 has been described. However, the present invention can also be applied to the configuration including the VVT mechanism driven by the electric actuator. It is. The present embodiment is an example in which the present invention is applied to a diesel engine, but the present invention can also be applied to a gasoline engine.

It is a figure which shows schematic structure of the control system of the internal combustion engine in an Example. It is a flowchart which shows the response speed correction | amendment control routine of VVT control in an Example. 7 is a flowchart illustrating a routine in a case where VVT control is executed prior to fuel injection control during acceleration transition in the embodiment. It is a figure which shows an example of the time change of the throttle opening, the positive overlap amount, the fuel injection amount, and the fuel pressure in the case where the VVT control is executed prior to the fuel injection control during the acceleration transition in the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Cylinder 3 Intake port 4 Exhaust port 5 Fuel injection valve 10 Intake valve 11 Exhaust valve 12 Intake camshaft 13 Exhaust camshaft 15 Piston 16 Connecting rod 17 Crankshaft 18 Revolution sensor 19 Water temperature sensor 20 ECU
22 Accelerator opening sensor 23 Combustion chamber 30 Intake passage 40 Exhaust passage 66 VVT mechanism 68 High-pressure fuel pump 70 OCV
72 Common rail 74 Cam position sensor 75 Fuel pressure sensor

Claims (7)

A camshaft for opening and closing an engine valve of an internal combustion engine;
A VVT mechanism that makes the valve timing of the engine valve variable by making the rotational phase of the camshaft variable with respect to the rotational phase of the crankshaft of the internal combustion engine;
Control means for driving the VVT mechanism to perform VVT control for changing the valve timing of the engine valve to a predetermined target valve timing;
A fuel injection valve for injecting fuel into the internal combustion engine;
Pressurizing means for pressurizing the fuel supplied to the fuel injection valve by the driving force of the camshaft;
Load calculating means for calculating a load applied to the camshaft to drive the pressurizing means based at least on the fuel injection amount by the fuel injection valve and the pressure of the fuel pressurized by the pressurizing means;
Correction means for correcting the change rate of the valve timing by the VVT control based on the load calculated by the load calculation means;
A control system for a variable valve mechanism of an internal combustion engine. In claim 1,
Response delay calculating means for calculating a response delay of the VVT control due to a load applied to the camshaft to drive the pressurizing means based on the load calculated by the load calculating means;
The control system for a variable valve mechanism of an internal combustion engine, wherein the correction means increases a change speed of the valve timing by the VVT control so as to correct the response delay calculated by the response delay calculation means. . In claim 2,
The VVT mechanism is a mechanism driven by a hydraulic actuator,
The control system for a variable valve mechanism of an internal combustion engine, wherein the response delay calculation means obtains the response delay of the VVT control in consideration of the oil temperature of the hydraulic oil of the hydraulic actuator. In any one of Claims 1-3,
The VVT mechanism is a mechanism driven by a hydraulic actuator,
The control system for a variable valve mechanism of an internal combustion engine, wherein the correction means increases a change speed of the valve timing by the VVT control by increasing an amount of hydraulic oil supplied to the hydraulic actuator. In any one of Claims 1-4,
The VVT mechanism is a mechanism driven by a hydraulic actuator,
The control system for a variable valve mechanism of an internal combustion engine, wherein the correction means increases a change speed of the valve timing by the VVT control by increasing a hydraulic pressure supplied to the hydraulic actuator. In any one of Claims 1-5,
An auxiliary means for assisting driving of the camshaft by the VVT mechanism;
In the variable valve mechanism for an internal combustion engine, the correction means increases the change speed of the valve timing by the VVT control by assisting the driving of the camshaft by the VVT mechanism by the auxiliary means. Control system. In any one of Claims 1-6,
VVT control for changing the valve timing of the engine valve to a target valve timing corresponding to the operating state after acceleration when the operating state of the internal combustion engine becomes an acceleration transient operating state, fuel injection amount by the fuel injection valve and A control system for a variable valve mechanism of an internal combustion engine, which is executed prior to control for changing the pressure of fuel pressurized by the pressurizing means to each target value corresponding to the operating state after acceleration. .

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