JP2010116835A - High-pressure pump control device for cylinder injection type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit under shoot of fuel pressure in return from fuel cut due to fuel pressure rise during a fuel cut period while preventing fuel pressure drop during the fuel cut period in a high-pressure fuel system. <P>SOLUTION: A high-pressure pump 14 is feedback controlled by PI control or the like so as to make actual fuel pressure in the high-pressure fuel system detected by a fuel pressure sensor 32 consistent with a target fuel pressure during normal operation period and the fuel cut period of the engine. Even during the fuel cut period, fuel pressure in the high pressure fuel system is controlled to the target fuel pressure by fuel pressure feedback control, and fuel pressure drop during the fuel cut period is prevented. Even if a state continues in which deviation of the actual fuel pressure and the target fuel pressure is large due to fuel pressure rise during the fuel cut period by keeping I gain during the fuel cut period smaller than I gain during the normal operation period, under shoot of fuel pressure in return from fuel cut is inhibited by inhibiting I term of fuel pressure feedback control from increasing large in a fuel pressure drop direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high pressure pump control device for a direct injection internal combustion engine that supplies high pressure fuel from a high pressure pump to a fuel injection valve.

  An in-cylinder injection engine that directly injects fuel into a cylinder has a shorter time from injection to combustion and sufficient time to atomize the injected fuel compared to an intake port injection engine that injects fuel into an intake port. Therefore, it is necessary to atomize the injected fuel by increasing the injection pressure. For this reason, in a direct injection engine, fuel pumped up from a fuel tank by a low pressure pump is supplied to a high pressure pump driven by the cam shaft of the engine, and high pressure fuel discharged from the high pressure pump is supplied to the fuel through a high pressure fuel pipe. Pressure is sent to the injection valve.

  In general, in a cylinder injection engine, a fuel pressure (fuel pressure) in a high-pressure fuel pipe is detected by a fuel pressure sensor, and the discharge amount of the high-pressure pump is feedback-controlled so that the fuel pressure detected by the fuel pressure sensor matches a target fuel pressure. Fuel pressure feedback control is performed. Here, the discharge amount of the high-pressure pump is controlled by controlling the closing timing of the on-off valve that is opened to suck the fuel in the fuel intake stroke (the timing at which fuel discharge is started after the fuel intake stroke). .

  In a system that performs such fuel pressure feedback control, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2007-32323), the high-pressure pump is controlled based on the deviation between the fuel pressure detected by the fuel pressure sensor and the target fuel pressure. By calculating the required discharge amount and controlling the closing timing of the open / close valve of the high-pressure pump according to this required discharge amount, the discharge amount of the high-pressure pump is controlled to the required discharge amount, and the fuel pressure in the high-pressure fuel pipe is set to the target fuel pressure. In some cases, the fuel pressure feedback control is stopped during the fuel cut period in which the fuel injection is stopped.

  In general, a check valve is provided on the discharge port side of the high-pressure pump to prevent the backflow of fuel in the high-pressure fuel pipe so that the fuel pressure in the high-pressure fuel pipe is maintained at a high pressure. If the fuel pressure in the high-pressure fuel pipe is maintained at a high level later, the amount of fuel leakage from the fuel injection valve tends to increase while the engine is stopped, and the leaked fuel accumulates in the cylinder and remains unburned at the next start-up. There is a problem that exhaust emissions at the time of start-up deteriorate.

As a countermeasure, as described in Patent Document 2 (Japanese Patent Laid-Open No. 2006-90222), a check valve with a leak function is provided on the discharge port side of the high-pressure pump, and after the engine is stopped (after the high-pressure pump is stopped) In addition, there is one in which the fuel pressure in the high-pressure fuel pipe is lowered by returning the fuel in the high-pressure fuel pipe to the low-pressure side through the pore formed in the check valve.
JP 2007-32323 A (pages 5 to 6 etc.) JP-A-2006-90222 (pages 6 to 7 etc.)

  By the way, the fuel in the high-pressure fuel pipe may leak to the low-pressure side due to aging deterioration of the check valve of the high-pressure pump, biting of foreign matter, or the like. In the technique of the above-mentioned patent document 1, since the fuel feedback control is stopped during the fuel cut period, if the fuel in the high pressure fuel pipe leaks to the low pressure side during the fuel cut period, the fuel pressure in the high pressure fuel pipe exceeds the target fuel pressure. There is also a drawback that it is lowered. Further, even in a configuration in which a check valve with a leak function is provided in the high-pressure pump as in the technique of Patent Document 2 above, the fuel in the high-pressure fuel pipe leaks to the low-pressure side during the fuel cut period, and the inside of the high-pressure fuel pipe There is a drawback that the fuel pressure of the fuel is lower than the target fuel pressure. If the fuel pressure in the high-pressure fuel pipe falls below the target fuel pressure during the fuel cut period, the injected fuel cannot be sufficiently atomized when the fuel cut is restored (when fuel injection is resumed), and the combustibility may be reduced. There is.

  As a countermeasure, it is conceivable to execute the fuel pressure feedback control during the fuel cut period. However, if the fuel pressure feedback control is executed during the fuel cut period under the same conditions as during the normal operation period, the following problems occur.

  During the fuel cut period, the fuel temperature in the high-pressure fuel pipe rises due to heat dissipation from the engine, and the fuel pressure in the high-pressure fuel pipe may become higher than the target fuel pressure. Because no fuel is consumed (injected), the fuel pressure cannot be reduced even if the fuel pressure feedback control is executed, and there is a large deviation between the actual fuel pressure and the target fuel pressure, and the integral term of the fuel pressure feedback control is the fuel pressure. It will continue to increase greatly in the downward direction. For this reason, even if fuel injection is resumed at the time of fuel cut recovery and the fuel consumption (required discharge amount) suddenly increases, the fuel pressure feedback control works in a direction to suppress the increase in the discharge amount of the high pressure pump. The discharge amount of the high-pressure pump cannot be increased with good response when cutting is restored. As a result, when the fuel cut is restored, the fuel pressure in the high-pressure fuel pipe may suddenly drop and an undershoot may occur that is significantly below the target fuel pressure.

  The present invention has been made in consideration of these circumstances. Therefore, the object of the present invention is to prevent a fuel pressure increase during the fuel cut period while preventing a decrease in the fuel pressure in the high pressure fuel system during the fuel cut period. An object of the present invention is to provide a high-pressure pump control device for a direct injection internal combustion engine that can suppress undershoot of fuel pressure at the time of cut recovery.

  In order to achieve the above object, the invention according to claim 1 makes the pressure of the fuel in the high-pressure fuel system (hereinafter referred to as “fuel pressure”) supplying high-pressure fuel from the high-pressure pump to the fuel injection valve coincide with the target fuel pressure. In a high-pressure pump control apparatus for a direct injection internal combustion engine equipped with fuel pressure control means for executing fuel pressure feedback control for feedback control of a high-pressure pump by a control method using at least an integral term (for example, PI control or PID control) The fuel pressure control means performs fuel pressure feedback control during a normal operation period in which fuel injection of the fuel injection valve is executed and during a fuel cut period in which the fuel injection is stopped, and during the normal operation period and the fuel cut period. The integral gain used for calculating the integral term is switched by integral gain switching means.

  In this configuration, since the fuel pressure feedback control is executed even during the fuel cut period, even if fuel leaks or returns from the high pressure fuel system to the low pressure side during the fuel cut period, the fuel pressure feedback control controls the inside of the high pressure fuel system. The fuel pressure can be maintained at the target fuel pressure to prevent the fuel pressure from decreasing. In addition, since the integral gain used for calculating the integral term is switched between the normal operation period and the fuel cut period, the actual fuel pressure and the target are increased during the fuel cut period due to the increase in fuel pressure due to the increase in the fuel temperature in the high-pressure fuel system. Even when the deviation from the fuel pressure continues to be large, the integral gain can be controlled so as to suppress the integral term of the fuel pressure feedback control from greatly increasing in the fuel pressure lowering direction. As a result, the fuel pressure in the high-pressure fuel system can be prevented from suddenly decreasing at the time of fuel cut return and the undershoot in which the fuel pressure falls below the target fuel pressure can be suppressed. The problem of deterioration of atomization and combustibility can be solved.

  Specifically, as in claim 2, the integral gain during the fuel cut period is preferably smaller than the integral gain during the normal operation period. In this way, since the change in the integral term of the fuel pressure feedback control during the fuel cut period can be made slower than during the normal operation period, the fuel temperature in the high-pressure fuel system rises during the fuel cut period. Even if the deviation between the actual fuel pressure and the target fuel pressure continues to be large due to the fuel pressure increase due to the fuel pressure, it is possible to reliably suppress the integral term of the fuel pressure feedback control from increasing in the fuel pressure decreasing direction. Moreover, the fuel pressure drop due to fuel leakage or return from the high pressure fuel system to the low pressure side during the fuel cut period is smaller than the fuel pressure increase due to the increase in fuel temperature in the high pressure fuel system. Even if the integral gain is made smaller than the integral gain during normal operation and the change in the integral term is moderated, fuel pressure drop control due to fuel leakage from the high-pressure fuel system to the low-pressure side and fuel pressure drop are sufficiently prevented. be able to.

  In the present invention, the integral gain during the fuel cut period may be a fixed value set in advance. However, as in claim 3, the degree of fuel leakage or return from the high pressure fuel system to the low pressure side during the fuel cut period. Accordingly, the integral gain during the fuel cut period may be learned by the integral gain learning means, and may be switched to the integral gain during the fuel cut period learned by the integral gain learning means during the fuel cut period. In this way, the integral term can be calculated using an appropriate integral gain according to the degree of fuel leakage or return from the high pressure fuel system to the low pressure side during the fuel cut period, and during the fuel cut period. The integration operation of the fuel pressure feedback control can be optimized according to the degree of fuel leakage or return.

  As a specific learning method of the integral gain during the fuel cut period, as in claim 4, the fuel pressure feedback control is temporarily stopped during the fuel cut period, and the internal pressure of the high pressure fuel system during the fuel pressure feedback control is stopped. The degree of fuel leakage or return from the high-pressure fuel system to the low-pressure side during the fuel cut period is learned by learning the integral gain during the fuel cut period in accordance with the degree of decrease in the fuel pressure (for example, the speed or amount of decrease). Accordingly, the integral gain during the fuel cut period may be learned.

  If the fuel pressure feedback control is stopped during the fuel cut period, the degree of fuel pressure reduction (for example, the rate of reduction or amount of reduction) in the high-pressure fuel system changes according to the degree of fuel leakage or return from the high-pressure fuel system to the low-pressure side. Therefore, the fuel pressure decrease rate during the stop of fuel pressure feedback control during the fuel cut period is information reflecting the degree of fuel leakage and return from the high pressure fuel system to the low pressure side during the fuel cut period. Therefore, if the integral gain during the fuel cut period is learned according to the degree of decrease in the fuel pressure in the high pressure fuel system during the stop of the fuel pressure feedback control during the fuel cut period, the high pressure fuel system during the fuel cut period is shifted from the low pressure side. The integral gain during the fuel cut period according to the degree of fuel leakage and return can be learned with high accuracy.

  In this case, as in claim 5, it is preferable to learn to increase the integral gain during the fuel cut period as the degree of decrease in the fuel pressure in the high-pressure fuel system when the fuel pressure feedback control is stopped increases. In this way, the integral gain during the fuel cut period increases as the degree of decrease in fuel pressure in the high-pressure fuel system increases (that is, the degree of fuel leakage or return from the high-pressure fuel system to the low-pressure side increases). Therefore, it is possible to control to accelerate the change of the integral term, and even if the degree of decrease in fuel pressure during the fuel cut period is large or small, fuel pressure decrease is reliably prevented by fuel pressure feedback control with appropriate integral gain accordingly be able to.

Hereinafter, an embodiment embodying the best mode for carrying out the present invention will be described.
First, a schematic configuration of the entire fuel supply system of an in-cylinder injection engine (internal combustion engine) will be described with reference to FIG.

  A low pressure pump 12 that pumps up the fuel is installed in the fuel tank 11 that stores the fuel. The low-pressure pump 12 is driven by an electric motor (not shown) that uses a battery (not shown) as a power source. The fuel discharged from the low pressure pump 12 is supplied to the high pressure pump 14 through the fuel pipe 13. A pressure regulator 15 is connected to the fuel pipe 13, and the discharge pressure of the low-pressure pump 12 (fuel supply pressure to the high-pressure pump 14) is regulated to a predetermined pressure by the pressure regulator 15, and surplus fuel exceeding that pressure Is returned to the fuel tank 11 by the fuel return pipe 16.

  The high-pressure pump 14 is a piston pump that reciprocates a piston 19 in a cylindrical pump chamber 18 and sucks / discharges fuel. The piston 19 rotates by a cam 21 fitted to a camshaft 20 of the engine. Driven by. A fuel pressure control valve 23 (open / close valve) is provided on the suction port 22 side of the high-pressure pump 14. The fuel pressure control valve 23 is a normally open type electromagnetic valve, and includes a valve body 24 that opens and closes the suction port 22, a spring 25 that urges the valve body 24 in the valve opening direction, and a valve body 24 in the valve closing direction. And a solenoid 26 that is electromagnetically driven.

  During the suction stroke of the high-pressure pump 14 (when the piston 19 is lowered), the fuel pressure control valve 23 is opened and fuel is sucked into the pump chamber 18, and during the discharge stroke of the high-pressure pump 14 (when the piston 19 is raised). By controlling the valve closing period of the fuel pressure control valve 23 (the crank angle section in the valve closing state from the valve closing start time to the top dead center of the piston 19), the discharge amount of the high pressure pump 14 is controlled to control the fuel pressure (discharge). Pressure).

  That is, when increasing the fuel pressure, the valve closing start timing (energization timing) of the fuel pressure control valve 23 is advanced, thereby extending the valve closing period of the fuel pressure control valve 23 and increasing the discharge amount of the high pressure pump 14. Conversely, when lowering the fuel pressure, the valve closing start timing (energization timing) of the fuel pressure control valve 23 is retarded, thereby shortening the valve closing period of the fuel pressure control valve 23 and reducing the discharge amount of the high-pressure pump 14. .

  On the other hand, a check valve 28 for preventing the backflow of discharged fuel is provided on the discharge port 27 side of the high-pressure pump 14. The fuel discharged from the high-pressure pump 14 is sent to the delivery pipe 30 through the high-pressure fuel pipe 29, and the high-pressure fuel is distributed from the delivery pipe 30 to the fuel injection valve 31 attached to the upper part of each cylinder of the engine. The delivery pipe 30 (or the high-pressure fuel pipe 29) is provided with a fuel pressure sensor 32 that detects the fuel pressure (fuel pressure) in the high-pressure fuel system such as the delivery pipe 30 and the high-pressure fuel pipe 29. The delivery pipe 30 is provided with a relief valve 33, and a discharge port of the relief valve 33 is connected to the fuel tank 11 (or the low-pressure side fuel pipe 13) via a relief pipe 34.

  The check valve 28 is provided with an orifice having a minute hole diameter, and when the fuel pressure in the pump chamber 18 is lower than the fuel pressure in the high-pressure fuel pipe 29, the fuel in the high-pressure fuel pipe 29 gradually passes through the orifice. It is good also as a structure which returns to the chamber 18 (low pressure side).

  Further, the engine is provided with an air flow meter 36 for detecting the amount of intake air and a crank angle sensor 37 for outputting a pulse signal at every predetermined crank angle in synchronization with rotation of a crankshaft (not shown). Based on the output signal of the crank angle sensor 37, the crank angle and the engine speed are detected.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 38. The ECU 38 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby determine the fuel injection amount of the fuel injection valve 31 according to the engine operating state. The ignition timing of a spark plug (not shown) is controlled.

  In addition, the ECU 38 detects the fuel pressure sensor 32 during a normal operation period in which the fuel injection of the fuel injection valve 31 is executed and a fuel cut period in which the fuel injection is stopped by executing a fuel pressure control routine of FIG. The discharge amount (energization timing of the fuel pressure control valve 23) of the high pressure pump 14 is controlled by a control method including an I term (integral term) such as PI control or PID control so that the actual fuel pressure in the high pressure fuel system matches the target fuel pressure. Fuel pressure feedback control for feedback control is executed. For example, in the case of PI control, the P term (proportional term) is calculated using the deviation between the target fuel pressure and the actual fuel pressure and the P gain (proportional gain), and the integral of the deviation between the target fuel pressure and the actual fuel pressure. The I term (integral term) is calculated using the value and the I gain (integral gain), and the feedback correction amount (for example, the correction amount of the energization timing of the fuel pressure control valve 23) is calculated using these P term and I term. Is calculated.

  At this time, in this embodiment, the I gain used for the calculation of the I term is switched between the normal operation period and the fuel cut period, so that the I gain during the fuel cut period is more than the I gain during the normal operation period. By making it smaller, the change in the I term of the fuel pressure feedback control during the fuel cut period becomes more gradual than during the normal operation period.

Hereinafter, the processing content of the fuel pressure control routine of FIG. 2 executed by the ECU 38 will be described.
The fuel pressure control routine shown in FIG. 2 is repeatedly executed at a predetermined cycle while the ECU 38 is powered on, and serves as fuel pressure control means in the claims. When this routine is started, first, at step 101, it is determined whether or not it is during the fuel cut period. As a result, if it is determined that it is not during the fuel cut period (during the normal operation period), the routine proceeds to step 102 and the engine operating state (for example, the engine speed, the deviation between the target fuel pressure and the actual fuel pressure, etc.). The I gain during the normal operation period corresponding to is calculated by a map or a mathematical formula, and is set as the I gain during the current normal operation period.

  On the other hand, if it is determined in step 101 that the fuel cut period is in progress, the process proceeds to step 103 to determine whether or not a predetermined I gain learning condition is satisfied. Here, as the I gain learning condition, for example, the fuel pressure sensor 32 is normal, the fuel pressure in the high pressure fuel system immediately before the fuel cut is greater than or equal to a predetermined value, and a predetermined period has elapsed since the previous learning of the I gain. Whether or not the I gain learning condition is satisfied is determined based on whether or not all of these conditions are satisfied.

  If it is determined in step 103 that the I gain learning condition is satisfied, the process proceeds to step 104 where the I gain during the fuel cut period is learned as follows. First, as shown in FIG. 3, the fuel pressure feedback control is temporarily stopped for a predetermined period during the fuel cut period, and the fuel pressure decrease amount ΔP and the stop time Δt in the high pressure fuel system during the stop of the fuel pressure feedback control, Based on the above, the fuel pressure decrease rate (ΔP / Δt) is calculated.

  If the fuel pressure feedback control is stopped during the fuel cut period, the rate of fuel pressure drop in the high pressure fuel system changes according to the degree of fuel leakage or return from the high pressure fuel system to the low pressure side. The fuel pressure drop rate (ΔP / Δt) in the high-pressure fuel system when feedback control is stopped is information reflecting the degree of fuel leakage or return from the high-pressure fuel system to the low-pressure side during the fuel cut period.

  Thereafter, with reference to the map of I gain during the fuel cut period shown in FIG. 4, the I gain during the fuel cut period corresponding to the fuel pressure decrease rate (ΔP / Δt) is calculated. The I gain map during the fuel cut period shown in FIG. 4 indicates that the I gain during the fuel cut period increases as the fuel pressure decrease rate (ΔP / Δt) increases, and the I gain during the fuel cut period is normal operation. It is set to be smaller than the I gain during the period.

  In this way, by learning the I gain during the fuel cut period according to the fuel pressure decrease rate (ΔP / Δt) in the high-pressure fuel system while the fuel pressure feedback control is stopped during the fuel cut period, The I gain during the fuel cut period according to the degree of fuel leakage and return from the high pressure fuel system to the low pressure side is accurately learned, and the learned value is set as the I gain during the current fuel cut period, A learning value of the I gain during the previous fuel cut period stored in a rewritable nonvolatile memory (a rewritable memory that retains stored data even when the ECU 38 is powered off) such as a backup RAM (not shown) of the ECU 38 Is updated with the learned value of the I gain during the current fuel cut period. The processing in step 104 serves as integral gain learning means in the claims.

  On the other hand, if it is determined in step 103 that the I gain learning condition is not satisfied, the process proceeds to step 105 without performing the learning of the I gain during the fuel cut period, and the non-volatile memory such as the backup RAM of the ECU 38 is The learned value of I gain during the previous fuel cut period stored in the memory is read, and the learned value is set as the I gain during the current fuel cut period.

  By performing the processes of steps 101 to 105, the I gain used for calculating the I term of the fuel pressure feedback control is switched between the normal operation period and the fuel cut period, and the I gain during the fuel cut period is changed during the normal operation period. Less than the I gain. This function serves as an integral gain switching means in the claims.

  As described above, after setting the I gain during the normal operation period or the I gain during the fuel cut period, the routine proceeds to step 106, where the target fuel pressure is determined according to the engine operating state (for example, engine speed, engine load, etc.). Is calculated by a map or numerical formula, and the discharge amount of the high-pressure pump 14 (energization of the fuel pressure control valve 23) is performed by PI control, PID control or the like so that the actual fuel pressure in the high-pressure fuel system detected by the fuel pressure sensor 32 matches the target fuel pressure. Fuel pressure feedback control is performed to feedback control the timing. At that time, during the normal operation period, the fuel pressure feedback control is executed using the calculated value of the I gain during the normal operation period, and during the fuel cut period, the fuel pressure feedback is performed using the learned value of the I gain during the fuel cut period. Execute control.

  In the present embodiment described above, the fuel pressure feedback control is executed even during the fuel cut period. Therefore, even if fuel leaks or returns from the high pressure fuel system to the low pressure side during the fuel cut period, the fuel pressure feedback control is performed. By controlling, the fuel pressure in the high-pressure fuel system can be maintained at the target fuel pressure, and a decrease in the fuel pressure in the high-pressure fuel system can be prevented.

  Further, the I gain used for calculating the I term of the fuel pressure feedback control is switched between the normal operation period and the fuel cut period so that the I gain during the fuel cut period is smaller than the I gain during the normal operation period. As a result, the change in the I term of the fuel pressure feedback control during the fuel cut period is moderated compared to during the normal operation period, so that the fuel pressure rises due to the increase in the fuel temperature in the high pressure fuel system during the fuel cut period. Therefore, even if the state where the deviation between the actual fuel pressure and the target fuel pressure is large continues, it is possible to suppress the I term of the fuel pressure feedback control from greatly increasing in the fuel pressure lowering direction. As a result, the fuel pressure in the high-pressure fuel system can be prevented from suddenly decreasing at the time of fuel cut return and the undershoot in which the fuel pressure falls below the target fuel pressure can be suppressed. The problem of deterioration of atomization and combustibility can be solved.

  Moreover, the fuel pressure drop due to fuel leakage or return from the high pressure fuel system to the low pressure side during the fuel cut period is smaller than the fuel pressure increase due to the increase in fuel temperature in the high pressure fuel system. Even if the I gain is made smaller than the I gain during the normal operation period and the change of the I term is moderated, fuel pressure drop control due to fuel leakage from the high pressure fuel system to the low pressure side and return is sufficiently prevented by fuel pressure feedback control. be able to.

  In this embodiment, the fuel pressure feedback control is temporarily stopped during the fuel cut period, and the I gain during the fuel cut period is set according to the rate of decrease in the fuel pressure in the high pressure fuel system during the stop of the fuel pressure feedback control. By learning, the I gain during the fuel cut period is learned according to the degree of leakage or return of fuel from the high pressure fuel system to the low pressure side during the fuel cut period, so the high pressure fuel during the fuel cut period The I term can be calculated using an appropriate I gain according to the degree of fuel leakage or return from the system to the low pressure side, and fuel pressure feedback control according to the degree of fuel leakage or return during the fuel cut period The integration operation can be optimized.

  At that time, since the I gain during the fuel cut period is increased as the fuel pressure decrease rate in the high pressure fuel system during the stop of the fuel pressure feedback control increases, the fuel pressure decrease rate in the high pressure fuel system increases ( In other words, as the degree of fuel leakage and return from the high-pressure fuel system to the low-pressure side increases, the I gain during the fuel cut period can be increased and the change in the I term can be accelerated, and the high pressure during the fuel cut period can be increased. It is possible to reliably prevent the fuel pressure from being reduced due to fuel leakage or return from the fuel system to the low pressure side by the fuel pressure feedback control.

  In the above embodiment, the I gain during the fuel cut period is learned in accordance with the rate of decrease in the fuel pressure in the high pressure fuel system while the fuel pressure feedback control is stopped during the fuel cut period. However, the present invention is not limited to this. The method of learning the I gain during the fuel cut period may be changed as appropriate, such as learning the I gain during the fuel cut period according to other information on the degree of decrease in the fuel pressure (for example, the amount of decrease in the fuel pressure). You may do it. Alternatively, the I gain during the fuel cut period may be set to a fixed value (for example, a value smaller than the I gain during the normal operation period) without learning the I gain during the fuel cut period.

  In addition, the present invention can be implemented with various modifications within a range not departing from the gist, such as appropriately changing the configuration of the fuel supply system.

It is a schematic block diagram of the whole fuel supply system in one Example of this invention. It is a flowchart explaining the flow of a process of a fuel pressure control routine. It is a time chart explaining the learning method of I gain during a fuel cut period. It is a figure which shows notionally an example of the map of I gain during a fuel cut period.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Fuel tank, 12 ... Low pressure pump, 14 ... High pressure pump, 22 ... Suction port, 23 ... Fuel pressure control valve, 27 ... Discharge port, 28 ... Check valve, 29 ... High pressure fuel piping, 30 ... Delivery pipe, 31 ... Fuel injection valve, 32 ... fuel pressure sensor, 38 ... ECU (fuel pressure control means, integral gain switching means, integral gain learning means)

Claims (5)

The high-pressure pump is fed back by a control method using at least an integral term so that the fuel pressure in the high-pressure fuel system (hereinafter referred to as “fuel pressure”) that supplies high-pressure fuel from the high-pressure pump to the fuel injection valve matches the target fuel pressure. In a high-pressure pump control device for a direct injection internal combustion engine provided with fuel pressure control means for performing fuel pressure feedback control to control,
The fuel pressure control means performs the fuel pressure feedback control during a normal operation period in which fuel injection of the fuel injection valve is executed and during a fuel cut period in which the fuel injection is stopped,
A high-pressure pump control device for a direct injection internal combustion engine, comprising integral gain switching means for switching an integral gain used for calculating the integral term between the normal operation period and the fuel cut period .   The high-pressure pump control device for a direct injection internal combustion engine according to claim 1, wherein the integral gain switching means makes the integral gain during the fuel cut period smaller than the integral gain during the normal operation period. . An integral gain learning means for learning an integral gain during the fuel cut period according to the degree of fuel leakage or return from the high pressure fuel system to the low pressure side during the fuel cut period;
The in-cylinder injection internal combustion engine according to claim 1 or 2, wherein the integral gain switching means switches to an integral gain during a fuel cut period learned by the integral gain learning means during the fuel cut period. High pressure pump control device.   The integral gain learning means temporarily stops the fuel pressure feedback control during the fuel cut period, and during the fuel cut period according to the degree of decrease in the fuel pressure in the high pressure fuel system during the stop of the fuel pressure feedback control. The integral gain during the fuel cut period is learned in accordance with the degree of fuel leakage or return from the high pressure fuel system to the low pressure side during the fuel cut period. The high-pressure pump control device for a direct injection internal combustion engine according to claim 3.   The integral gain learning means learns to increase the integral gain during the fuel cut period as the degree of decrease in the fuel pressure in the high pressure fuel system during the stop of the fuel pressure feedback control increases. 4. A high pressure pump control device for a direct injection internal combustion engine according to claim 4.

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