JP2010196472A - Fuel supply control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately learn the controlled variable of a fuel pressure control valve of a high-pressure pump, in a fuel pressure feedback control system which feedback-controls the fuel delivery rate (fuel pressure on a high-pressure side) of the high-pressure pump according to deviation between fuel pressure detected by a fuel pressure sensor and target fuel pressure. <P>SOLUTION: The controlled variable or feedback correction amount of the fuel pressure control valve 22 is learned with respect to each region of a parameter affecting the fuel pressure at the high-pressure side during performance of fuel pressure feedback control, and a learned value is updated and stored in a rewritable storage means (for example, a backup RAM 35) storing storage data even if an engine is stopped (the power source of an ECU 34 is turned off). At least one of the amount of fuel injected, engine speed, the fuel pressure at the high-pressure side, the coil temperature of the fuel pressure control valve 22, a fuel temperature, fuel pressure (fuel pressure on a low-pressure side) in a low-pressure fuel pipe 13, cylinder internal pressure and a fuel injection pattern is used as the parameter affecting the fuel pressure at the high-pressure side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel supply control device for an internal combustion engine that controls a fuel discharge amount of a high-pressure pump in accordance with a deviation between a fuel pressure (fuel pressure) detected by a fuel pressure sensor and a target fuel pressure.

  In recent years, there is an increasing demand for in-cylinder injection engines that have the features of low fuel consumption, low emission, and high output. In this in-cylinder injection engine, it is necessary to increase the injection pressure in order to atomize (atomize) the fuel directly injected into the cylinder. Therefore, the fuel in the fuel tank is pumped up by a low-pressure pump, and the fuel is A high pressure pump is used to increase the pressure and feed the fuel to the fuel injection valve.

  Generally, as described in Patent Document 1 (Japanese Patent No. 3978655), a high-pressure pump sucks / discharges fuel by reciprocating a plunger in a pump chamber by a cam fitted to a cam shaft of an engine. Like to do. Control of the fuel discharge amount (fuel pressure supplied to the fuel injection valve) of this high-pressure pump is provided with a normally open fuel pressure control valve in which a valve body that opens and closes the suction port of the pump chamber is biased in the valve opening direction by a spring. High pressure pump by controlling the start timing of closing the fuel pressure control valve during the discharge stroke by controlling the start timing of the fuel pressure control valve during the discharge stroke (the stroke when the plunger moves from the bottom dead center to the top dead center) The fuel pressure supplied to the fuel injection valve is controlled by controlling the fuel discharge amount. For example, to increase the fuel discharge amount, advance the valve closing start timing of the fuel pressure control valve to lengthen the valve closing period until the end of the discharge stroke, and conversely to decrease the fuel discharge amount, the fuel pressure control valve The valve closing start time is delayed so that the valve closing period until the end of the discharge stroke is shortened.

  Although control of the fuel discharge amount (fuel pressure) of this high-pressure pump is performed by feed-forward control (open loop control), as described in Patent Document 2 (Japanese Patent Laid-Open No. 2007-32323), fuel A fuel pressure sensor that detects the fuel pressure supplied to the injection valve is provided, and the control amount of the fuel pressure control valve closing start timing is feedback controlled so that the deviation between the fuel pressure detected by the fuel pressure sensor and the target fuel pressure is reduced by fuel pressure feedback control. There are also things to do.

  In such a fuel pressure feedback control system, if the fuel pressure sensor or the like fails, the fuel discharge amount (fuel pressure) of the high-pressure pump cannot be controlled. Therefore, as described in Patent Document 3 (Japanese Patent No. 3827814), the high pressure pump When the pump control system fails, the control of the high-pressure pump is stopped, and the internal combustion engine is operated by supplying fuel to the fuel injection valve only by the low-pressure electric fuel pump that supplies fuel to the high-pressure pump. There is something that was made. However, if fuel is supplied to the fuel injection valve only with the electric fuel pump on the low pressure side, there is a disadvantage that the range in which the vehicle can travel is limited because the fuel pressure is extremely insufficient.

  Further, in an intake port injection engine without a high-pressure pump, as described in Patent Document 4 (Patent No. 3060266), the learning correction amount for the basic control amount of the electric fuel pump is set as an engine operating condition (specifically, (Each engine rotation speed and fuel injection amount) is learned for each region, and the control amount of the electric fuel pump is set by adding the learning correction amount to the basic control amount according to the engine operating conditions, and the fuel discharge amount of the electric fuel pump There is a feed-forward control of (fuel pressure).

Japanese Patent No. 3978655 JP 2007-32323 A Japanese Patent No. 3827814 Japanese Patent No. 3060266

  By the way, when the learning technique of Patent Document 4 for the intake port injection engine is applied to the control system for the fuel discharge amount (fuel pressure) of the high-pressure pump in the cylinder injection engine, the feed-forward control of the fuel discharge amount (fuel pressure) of the high-pressure pump ( For a system that performs open loop control), it is conceivable to learn the learning correction amount for the basic control amount of the high-pressure pump. However, this is a system that feedback-controls the fuel discharge amount (fuel pressure) of the high-pressure pump equipped with a fuel pressure sensor. On the other hand, the learning technique of Patent Document 4 cannot be applied as it is. Also, the control of the high-pressure pump includes many error factors when parameters that affect fuel pressure under the same operating conditions (for example, fuel injection amount, internal combustion engine speed, fuel pressure, fuel pressure control valve coil temperature, fuel temperature, etc.) change. Because the fuel pressure cannot be accurately controlled to the target fuel pressure, learning the control amount of the high-pressure pump in this state results in a large amount of error factors being included in the learned value, which in turn deteriorates the control accuracy. It becomes.

  Therefore, the problem to be solved by the present invention is to control the fuel pressure control valve of the high-pressure pump in a system that controls the fuel discharge amount (fuel pressure) of the high-pressure pump according to the deviation between the fuel pressure detected by the fuel pressure sensor and the target fuel pressure. An object of the present invention is to provide a fuel supply control device for an internal combustion engine that can learn the amount accurately.

  In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that the plunger that is reciprocally driven in the pump chamber by the power of the internal combustion engine and opens and closes the intake port for sucking fuel into the pump chamber. A high-pressure pump having an open fuel pressure control valve and a pressure of fuel in a high-pressure fuel pipe that supplies fuel discharged from a discharge port of the high-pressure pump to a fuel injection valve (hereinafter referred to as “high-pressure side fuel pressure”) are detected. The fuel discharge amount of the high-pressure pump is controlled by controlling the closing period of the fuel pressure control valve in the discharge stroke of the high-pressure pump according to the deviation between the fuel pressure sensor and the high-pressure side fuel pressure detected by the fuel pressure sensor and the target fuel pressure A fuel supply control device for an internal combustion engine comprising a high-pressure pump control means that performs a control amount or a control amount of the fuel pressure control valve for each parameter region affecting the high-pressure side fuel pressure by a learning means. Learning the correction amount is obtained by the learning value to be updated and stored in a storage means rewriting that can retain stored data even during stop of the internal combustion engine. In this configuration, since the control amount of the fuel pressure control valve or the correction amount thereof is learned for each parameter region that affects the high-pressure side fuel pressure, the control amount of the fuel pressure control valve or the correction amount thereof can be learned with high accuracy.

  Specifically, the parameters affecting the high-pressure side fuel pressure include the fuel injection amount, the internal combustion engine rotational speed, the high-pressure side fuel pressure, the coil temperature of the fuel pressure control valve, the fuel temperature, and the intake port of the high-pressure pump. It is preferable to use at least one of a fuel pressure (hereinafter referred to as “low pressure side fuel pressure”), an in-cylinder pressure, and a fuel injection pattern in a low-pressure fuel pipe connected to. Here, the fuel injection amount and the internal combustion engine rotational speed are parameters that change the high-pressure side fuel pressure in order to change the fuel outflow amount in the high-pressure fuel pipe. The coil temperature of the fuel pressure control valve is a parameter that affects the high-pressure side fuel pressure because the resistance value and current value of the coil are changed to change the valve closing characteristics of the fuel pressure control valve (time from the start of energization to closing). is there. The fuel temperature is a parameter that affects the high-pressure side fuel pressure in order to change the coil temperature of the fuel pressure control valve. The low-pressure side fuel pressure is a parameter that affects the high-pressure side fuel pressure because the amount of fuel sucked into the high-pressure pump is changed. As the in-cylinder pressure increases, the amount of fuel injected from the fuel injection valve into the cylinder decreases, so the in-cylinder pressure is also a parameter that affects the high-pressure side fuel pressure. The fuel injection pattern is a parameter that determines when to perform divided injection that is divided into multiple injections or during the intake stroke or the compression stroke. The in-cylinder pressure at the time of injection changes depending on the injection timing. The pattern is also a parameter that affects the high-pressure side fuel pressure.

  In this case, as in the third aspect, it is preferable to include a learning prohibiting unit that prohibits learning under a condition that the learning error of the learning value is large. Thereby, the fall of learning accuracy can be prevented reliably.

  Specifically, as in claim 4, learning is preferably prohibited when coil temperature of the fuel pressure control valve or temperature information correlated therewith is out of a predetermined range. Here, the temperature information correlated with the coil temperature of the fuel pressure control valve is, for example, the cooling water temperature of the internal combustion engine, the oil temperature, the temperature of the fuel injection valve, the fuel temperature, the oil temperature of the automatic transmission, and the like. When the fuel temperature is too high, vapor (bubbles) may be generated in the fuel sucked into the high-pressure pump. Further, during the warm-up operation of the internal combustion engine, the coil temperature of the fuel pressure control valve rises relatively large from the low temperature state, and the resistance value of the coil of the fuel pressure control valve changes relatively large. It is desirable to learn the control amount of the fuel pressure control valve or its correction amount after the temperature has risen to the temperature range after warm-up where the change in the coil resistance value is small.

  Further, as in the fifth aspect, the learning is preferably prohibited when the high-pressure side fuel pressure or the low-pressure side fuel pressure detected by the fuel pressure sensor is out of a predetermined range. When the high-pressure side fuel pressure is out of the predetermined range (when greatly deviating from the target fuel pressure), there is a possibility that it is immediately after starting or during a transition, or that the high-pressure side fuel system is abnormal. If the low-pressure side fuel pressure is too low, vapor (bubbles) may be generated in the fuel sucked into the high-pressure pump. If the low-pressure side fuel pressure is too high, the low-pressure side fuel system may be abnormal.

  Further, as in claim 6, learning is preferably prohibited when the required fuel injection amount is equal to or less than the minimum injection amount within the guaranteed injection range of the fuel injection valve. This is because when the required fuel injection amount is less than or equal to the minimum injection amount within the guaranteed injection range of the fuel injection valve, fuel for the required fuel injection amount cannot be injected accurately.

  According to another aspect of the present invention, means for feedback controlling the control amount of the fuel pressure control valve so as to reduce the deviation between the high-pressure side fuel pressure detected by the fuel pressure sensor and the target fuel pressure, and stored when the feedback control cannot be executed. It is preferable to have a configuration including means for open-loop control of the control amount of the fuel pressure control valve using the learning value stored in the means. In this way, even when the feedback control cannot be executed, for example, when the fuel pressure sensor is abnormal or when the feedback control execution condition is not satisfied, the control value of the fuel pressure control valve can be open-loop controlled using the learning value. This makes it possible to control the fuel discharge amount of the high-pressure pump while ensuring control accuracy during open loop control.

FIG. 1 is a diagram showing a schematic configuration of an entire fuel injection system showing an embodiment of the present invention. FIG. 2 is a diagram for explaining the relationship between energization on / off of the fuel pressure control valve of the high-pressure pump and fuel intake / discharge. FIG. 3 is a time chart for explaining energization control of the fuel pressure control valve of the high-pressure pump. FIG. 4 is a flowchart showing the flow of processing of the high-pressure pump control main routine. FIG. 5 is a flowchart showing the flow of processing of the learning execution condition determination routine. FIG. 6 is a flowchart showing the flow of the learning area determination routine. FIG. 7 is a flowchart showing the flow of the learning value update routine. FIG. 8 is a diagram conceptually illustrating an example of a learning map.

Hereinafter, an embodiment embodying a mode for carrying out the present invention will be described.
First, based on FIG. 1, the structure of the whole fuel supply system of a cylinder injection engine (internal combustion engine) is demonstrated.

  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 low pressure fuel pipe 13. A pressure regulator 15 is connected to the low-pressure fuel pipe 13, and the discharge pressure (low-pressure side fuel pressure) of the low-pressure pump 12 is adjusted to a predetermined pressure by the pressure regulator 15, and surplus fuel exceeding the pressure is a fuel return pipe. 16 is returned to the fuel tank 11.

  As shown in FIG. 2, the high-pressure pump 14 is a plunger pump that sucks / discharges fuel by reciprocating a plunger 19 in a pump chamber 18. The plunger 19 is a cam fitted to a camshaft 20 of an engine. It is driven by the rotational movement of 21. On the suction port 23 side of the high-pressure pump 14, a fuel pressure control valve 22 comprising a normally open type electromagnetic valve is provided. The fuel pressure control valve 22 includes a valve body 24 that opens and closes the suction port 23, a spring 25 (biasing means) that urges the valve body 24 in the valve opening direction, and electromagnetically drives the valve body 24 in the valve closing direction. When the energization to the coil 26 is turned off, the valve body 24 is held in a state where the inlet 23 is opened by the spring 25, and when the energization to the coil 26 is turned on, the coil 26 The valve body 24 closes the suction port 23 by an electromagnetic suction force.

  During the intake stroke of the high-pressure pump 14 (when the plunger 19 is lowered), the energization of the fuel pressure control valve 22 is maintained in the off state, and the valve body 24 of the fuel pressure control valve 22 is maintained in the opened state by the spring 25. Therefore, fuel is sucked into the pump chamber 18 from the suction port 23 as the plunger 19 is lowered. On the other hand, in the discharge stroke (when the plunger 19 is raised), the high pressure pump is controlled by controlling the valve closing period of the fuel pressure control valve 22 (the valve closing state period from the valve closing start time to the top dead center of the plunger 19). The fuel discharge amount of 14 is controlled to control the high-pressure side fuel pressure.

  That is, when increasing the high-pressure side fuel pressure, the valve closing start timing (energization start timing) of the fuel pressure control valve 22 is advanced, thereby extending the valve closing period of the fuel pressure control valve 22 and the fuel discharge amount of the high pressure pump 14. On the contrary, when the high-pressure side fuel pressure is decreased, the valve closing start timing (energization start timing) of the fuel pressure control valve 22 is retarded, so that the valve closing period of the fuel pressure control valve 22 is shortened. The fuel discharge amount of 14 is decreased.

  As shown in FIG. 3, during a predetermined period from when the fuel pressure control valve 22 is energized until the valve body 24 is closed, the coil 26 of the fuel pressure control valve 22 is energized with a 100% duty and the fuel pressure control valve 22. The valve is quickly closed, and thereafter energized with a predetermined holding duty, and a minimum current required to hold the fuel pressure control valve 22 in the closed state is caused to flow through the coil 26. The fuel pressure control valve 22 is kept closed until the top dead center.

  In order to reduce the power consumption of the high-pressure pump 14, after the energization of the fuel pressure control valve 22 is started and the fuel pressure control valve 22 is closed during the discharge stroke, as described in Japanese Patent No. 3978655. When the fuel closing pressure (fuel pressure) acting on the valve body 24 of the fuel pressure control valve 22 becomes larger than the valve opening force due to the urging force of the spring 25 due to the increase of the fuel pressure in the pump chamber 18, the fuel pressure control valve By turning off the power to 22, “self-closed control” for holding the valve body 24 of the fuel pressure control valve 22 in the closed state by the fuel pressure in the pump chamber 18 until the discharge stroke is completed even after the power is turned off. You may make it do.

  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. As shown in FIG. 1, the fuel discharged from the high-pressure pump 14 is sent to a delivery pipe 30 through a high-pressure fuel pipe 29, and from the delivery pipe 30 to a fuel injection valve 31 attached to the cylinder head of the engine for each cylinder. High pressure fuel is dispensed. The high-pressure fuel pipe 29 is provided with a fuel pressure sensor 32 that detects a high-pressure side fuel pressure, and the engine cylinder block is provided with a cooling water temperature sensor 33 that detects a cooling water temperature.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 34. This ECU 34 is mainly composed of a microcomputer, and by fuel pressure feedback control, the fuel discharge amount of the high-pressure pump 14 (the start time of energization of the fuel pressure control valve 22) so that the high-pressure side fuel pressure detected by the fuel pressure sensor 29 matches the target fuel pressure. ) Is feedback controlled. In this fuel pressure feedback control, the required fuel discharge amount is calculated by a map or the like according to the engine operating state (engine speed, intake air amount, intake pipe pressure, etc.), and the fuel pressure control valve 22 according to the required fuel discharge amount. The basic control amount of the energization start time is calculated by a map or the like, the feedback correction amount for the basic control amount is calculated according to the deviation between the detected fuel pressure of the fuel pressure sensor 29 and the target fuel pressure, and the basic correction amount is calculated based on the feedback correction amount. The control amount is corrected to set the control amount of the energization start timing of the fuel pressure control valve 22.

  Further, in this embodiment, during the execution of the fuel pressure feedback control, the feedback correction amount with respect to the basic control amount of the energization start timing of the fuel pressure control valve 22 is learned for each parameter area that affects the high-pressure side fuel pressure, and the learned value is used as the engine value. Even when the ECU 34 is stopped (when the ECU 34 is powered off), it is updated and stored in, for example, a backup RAM 35 which is a rewritable storage means capable of holding stored data. Instead of the backup RAM 35, the learning value may be updated and stored in a rewritable nonvolatile memory such as an EEPROM.

  In this case, parameters affecting the high-pressure side fuel pressure include the fuel injection amount, the engine speed, the high-pressure side fuel pressure, the coil temperature of the fuel pressure control valve 22, the fuel temperature, the fuel pressure in the low-pressure fuel pipe 13 (hereinafter referred to as “low-pressure side fuel pressure”). It is preferable to use at least one of in-cylinder pressure and fuel injection pattern. Here, the fuel injection amount and the engine rotation speed are parameters for changing the high-pressure side fuel pressure in order to change the fuel consumption in the high-pressure fuel pipe 29. The coil temperature of the fuel pressure control valve 22 changes the resistance value / current value of the coil 25 to change the valve closing characteristic (time from the start of energization to the valve closing time) of the fuel pressure control valve 22, and therefore affects the high-pressure side fuel pressure. It is a parameter to do. The fuel temperature is a parameter that affects the high-pressure side fuel pressure in order to change the coil temperature of the fuel pressure control valve 22. The low-pressure side fuel pressure is a parameter that affects the high-pressure side fuel pressure because the amount of fuel sucked into the high-pressure pump 14 is changed. As the in-cylinder pressure increases, the amount of fuel injected from the fuel injection valve 31 into the cylinder decreases, so the in-cylinder pressure is also a parameter that affects the high-pressure side fuel pressure. The fuel injection pattern is a parameter that determines when to perform divided injection that is divided into multiple injections or during the intake stroke or the compression stroke. The in-cylinder pressure at the time of injection changes depending on the injection timing. The pattern is also a parameter that affects the high-pressure side fuel pressure.

In this case, in order to surely prevent a decrease in learning accuracy, it is preferable to prohibit learning under conditions where the learning error of the learning value increases.
Specifically, learning is preferably prohibited when the coil temperature of the fuel pressure control valve 22 or temperature information correlated therewith is out of a predetermined range. Here, the temperature information correlated with the coil temperature of the fuel pressure control valve 22 is, for example, the engine coolant temperature, the oil temperature, the temperature of the fuel injection valve 31, the fuel temperature, the oil temperature of the automatic transmission, and the like. When the fuel temperature is too high, vapor (bubbles) may be generated in the fuel sucked into the high-pressure pump 14. Further, during the warm-up operation of the engine, the coil temperature of the fuel pressure control valve 22 rises relatively large from the low temperature state, and the resistance value of the coil 26 of the fuel pressure control valve 22 changes relatively large. It is desirable to learn the feedback correction amount of the fuel pressure control valve 22 after the coil temperature (resistance value of the coil 26) has risen to a temperature range where the change is small.

  Further, it is preferable to prohibit learning when the high-pressure side fuel pressure or the low-pressure side fuel pressure detected by the fuel pressure sensor 32 is out of a predetermined range. When the high-pressure side fuel pressure is out of the predetermined range (when greatly deviating from the target fuel pressure), there is a possibility that it is immediately after starting or during a transition, or that the high-pressure side fuel system is abnormal. If the low-pressure side fuel pressure is too low, vapor (bubbles) may be generated in the fuel sucked into the high-pressure pump 14. If the low-pressure side fuel pressure is too high, the low-pressure side fuel system may be abnormal.

  Further, it is preferable that the learning is prohibited when the required fuel injection amount is equal to or less than the minimum injection amount within the guaranteed injection range of the fuel injection valve 31. This is because when the required fuel injection amount is equal to or less than the minimum injection amount within the guaranteed injection range of the fuel injection valve 31, fuel for the required fuel injection amount cannot be injected accurately.

Further, when the fuel pressure feedback control cannot be executed, the control value of the energization start timing of the fuel pressure control valve 22 may be subjected to open loop control using the learning value stored in the backup RAM 35. In this way, even when the fuel pressure feedback control cannot be executed, for example, when the fuel pressure sensor 32 is abnormal or when the feedback control execution condition is not satisfied, the energization start timing of the fuel pressure control valve 22 is controlled using the learned value. The amount can be controlled in an open loop, and the fuel discharge amount of the high-pressure pump 14 can be controlled while ensuring the control accuracy during the open loop control.
The control of the high-pressure pump 14 according to the present embodiment described above is executed by the ECU 34 according to the routines shown in FIGS. The processing contents of these routines will be described below.

[High-pressure pump control main routine]
The high-pressure pump control main routine of FIG. 4 is repeatedly executed at a predetermined cycle during the power-on period of the ECU 34 (while the ignition switch is on). When this routine is started, first, at step 100, a fuel pressure feedback control routine (not shown) is executed, and a feedback correction amount is calculated according to the deviation between the high-pressure side fuel pressure detected by the fuel pressure sensor 29 and the target fuel pressure. Then, the basic control amount set according to the required fuel discharge amount is corrected with the feedback correction amount, and the control amount of the energization start timing of the fuel pressure control valve 22 is set, so that the deviation between the high-pressure side fuel pressure and the target fuel pressure is set. Thus, the amount of fuel discharged from the high pressure pump 14 is feedback controlled. The processing in step 100 serves as high-pressure pump control means in the claims.

Thereafter, the process proceeds to step 200, and a learning execution condition determination routine shown in FIG. 5 described later is executed to determine whether or not the learning execution condition is satisfied. Then, the process proceeds to step 300, and a learning area determination routine shown in FIG. It is executed to determine which region of the learning region (learning map) the current driving region belongs to (determine the region to be learned this time among the learnable regions). Thereafter, the process proceeds to step 400, where a learning value calculation routine of FIG. 7 described later is executed to calculate a learning value, and in the next step 500, the learning map stored in the backup RAM 35 (see FIG. 8). Then, the storage data of the learning value of the region to be learned this time is updated with the learning value calculated in step 400 above.
The processes in steps 200 to 500 described above serve as learning means in the claims.

[Learning execution condition judgment routine]
The learning execution condition determination routine of FIG. 5 is a subroutine executed in step 200 of the high-pressure pump control main routine of FIG. 4 and serves as learning prohibiting means in the claims. When this routine is started, first, at step 201, the coil temperature of the fuel pressure control valve 22, which is the first condition among the learning execution conditions, is within a predetermined range (predetermined value K1 <coil temperature <predetermined value K2). If it is determined that the coil temperature is out of the predetermined range, the process proceeds to step 205, where it is determined that the learning execution condition is not satisfied, and learning is prohibited.

  If it is determined in step 201 that the coil temperature of the fuel pressure control valve 22 is within a predetermined range (predetermined value K1 <coil temperature <predetermined value K2), the process proceeds to step 202 and the second of the learning execution conditions. It is determined whether the high-pressure side fuel pressure detected by the fuel pressure sensor 32 is within a predetermined range (predetermined value K3 <high-pressure side fuel pressure <predetermined value K4). As a result, the high-pressure side fuel pressure falls from the predetermined temperature range. If it is determined that it is not, the process proceeds to step 205, where it is determined that the learning execution condition is not satisfied, and learning is prohibited.

  If it is determined in step 202 that the high-pressure side fuel pressure is within a predetermined range (predetermined value K3 <high-pressure side fuel pressure <predetermined value K4), the process proceeds to step 203, which is the third condition of the learning execution conditions. Then, it is determined whether or not the required fuel injection amount is larger than a predetermined value K5 (a value corresponding to the minimum injection amount in the guaranteed injection range of the fuel injection valve 31), and as a result, the required fuel injection amount is equal to or less than the predetermined value K5. If it is determined, it is determined that the fuel for the required fuel injection amount cannot be accurately injected, the process proceeds to step 205, where it is determined that the learning execution condition is not satisfied, and learning is prohibited.

  If all of the three steps 201 to 203 described above are determined as “Yes” (when all the above three conditions are satisfied), the process proceeds to step 204 and it is determined that the learning execution condition is satisfied. To do.

[Learning area determination routine]
The learning region determination routine of FIG. 6 is a subroutine executed in step 300 of the high-pressure pump control main routine of FIG. When this routine is started, first, in step 301, the current engine speed Ne is read. In the next step 302, the high-pressure side fuel pressure detected by the fuel pressure sensor 32 is read. In the next step 303, fuel injection is performed. Read the amount TAU. After this, the process proceeds to step 304, and it is determined which of the areas (learning maps) in which the current operation area (Ne, HP, TAU) can be learned (the area to be learned this time among the areas that can be learned) ).

[Learning value calculation routine]
The learning value calculation routine of FIG. 7 is a subroutine executed in step 400 of the high-pressure pump control main routine of FIG. When this routine is started, first, in step 401, it is determined whether the learning execution condition is satisfied based on the processing result of the learning execution condition determination routine of FIG. 5, and it is determined that the learning execution condition is not satisfied. If so, the routine is terminated without calculating the learning value P (Ne, HP, TAU).

  On the other hand, if it is determined in step 401 that the learning execution condition is satisfied, the process proceeds to step 402, where the learning value P (Ne, HP) stored in the current learning region (Ne, HP, TAU) is processed. HP, TAU) and the current feedback correction amount are used to calculate a new learning value P (Ne, HP, TAU) by the following smoothing equation.

P (Ne, HP, TAU)
= (1−k) × P (Ne, HP, TAU) + k × feedback correction amount Here, k is a smoothing coefficient, and is set in a range of 0 <k <1.

  For example, in FIG. 8, when the region to be learned this time is (ne1, hp2, tau2), the learning value P (ne1, hp2, tau2) stored in the region is updated with the newly calculated learning value. .

  The learning value P (Ne, HP, TAU) updated as described above is used when the fuel pressure feedback control cannot be executed. For example, since the fuel pressure feedback control cannot be executed when the fuel pressure sensor 32 is abnormal or when the feedback control execution condition is not satisfied, the fuel discharge amount of the high-pressure pump 14 is set using the learning value P (Ne, HP, TAU). Open loop control. In this open loop control, the basic control amount is set by a map or the like according to the current operation area (Ne, HP, TAU), and learning stored in the learning area corresponding to the operation area (Ne, HP, TAU). By correcting the basic control amount with the value P (Ne, HP, TAU) and setting the control amount at the energization start timing of the fuel pressure control valve 22, the fuel discharge amount of the high-pressure pump 14 is controlled in an open loop. Thereby, even when the fuel pressure feedback control cannot be executed, the fuel discharge amount of the high pressure pump 14 can be controlled while ensuring the control accuracy by the open loop control.

  According to the present embodiment described above, the feedback correction amount of the fuel pressure control valve 31 is learned for each parameter region (Ne, HP, TAU) that affects the high-pressure side fuel pressure. I can learn well.

  Note that the parameter regions that affect the high-pressure side fuel pressure are not limited to the engine speed Ne, the high-pressure side fuel pressure HP, and the fuel injection amount TAU, but the engine speed Ne, the high-pressure side fuel pressure HP, the fuel injection amount TAU, and the fuel pressure control valve. At least one of 22 coil temperature, fuel temperature, low pressure side fuel pressure, in-cylinder pressure, and fuel injection pattern may be used.

  In this embodiment, the feedback correction amount is learned. However, the control amount corrected by the feedback correction amount may be learned. In this case, when performing the open loop control, the learning value stored in the learning region corresponding to the current operation region is set as it is as the control amount of the energization start timing of the fuel pressure control valve 22, and the fuel of the high pressure pump 14 is set. The discharge amount may be controlled by open loop.

  DESCRIPTION OF SYMBOLS 11 ... Fuel tank, 12 ... Low pressure pump, 13 ... Low pressure fuel piping, 14 ... High pressure pump, 19 ... Plunger, 20 ... Cam shaft, 21 ... Cam, 22 ... Fuel pressure control valve, 23 ... Inlet, 24 ... Valve body, DESCRIPTION OF SYMBOLS 25 ... Spring (biasing means), 26 ... Coil, 27 ... Discharge port, 28 ... Check valve, 29 ... High pressure fuel piping, 30 ... Delivery pipe, 31 ... Fuel injection valve, 32 ... Fuel pressure sensor, 34 ... ECU ( High pressure pump control means, learning means, learning prohibition means), 35 ... backup RAM (storage means)

Claims (7)

A high-pressure pump having a plunger that is reciprocally driven in the pump chamber by the power of the internal combustion engine and sucks / discharges fuel, and a normally-open fuel pressure control valve that opens and closes a suction port that sucks fuel into the pump chamber; A fuel pressure sensor for detecting fuel pressure (hereinafter referred to as “high pressure side fuel pressure”) in a high pressure fuel pipe that supplies fuel discharged from the discharge port to the fuel injection valve, and a high pressure side fuel pressure and a target fuel pressure detected by the fuel pressure sensor. And a high pressure pump control means for controlling a fuel discharge amount of the high pressure pump by controlling a valve closing period of the fuel pressure control valve in a discharge stroke of the high pressure pump according to a deviation from In
The control amount of the fuel pressure control valve or its correction amount is learned for each parameter region that affects the high-pressure side fuel pressure, and the learned value is updated and stored in a rewritable storage means that can retain stored data even when the internal combustion engine is stopped. A fuel supply control device for an internal combustion engine, comprising learning means for performing the learning.   Parameters affecting the high-pressure side fuel pressure include fuel injection amount, internal combustion engine rotational speed, high-pressure side fuel pressure, coil temperature of the fuel pressure control valve, fuel temperature, fuel pressure in the low-pressure fuel pipe connected to the suction port of the high-pressure pump ( 2. The fuel supply control device for an internal combustion engine according to claim 1, wherein the fuel supply control device is at least one of a cylinder pressure and a fuel injection pattern.   3. The fuel supply control device for an internal combustion engine according to claim 1, wherein the learning unit includes a learning prohibiting unit that prohibits learning under a condition in which a learning error of the learning value increases.   4. The fuel for an internal combustion engine according to claim 3, wherein the learning prohibiting unit prohibits learning when the coil temperature of the fuel pressure control valve or temperature information correlated therewith is out of a predetermined range. Supply control device.   5. The fuel supply of the internal combustion engine according to claim 3, wherein the learning prohibiting unit prohibits learning when the high-pressure side fuel pressure or the low-pressure side fuel pressure detected by the fuel pressure sensor is out of a predetermined range. Control device.   6. The learning prohibiting unit prohibits learning when the required fuel injection amount is equal to or less than a minimum injection amount within a guaranteed injection range of the fuel injection valve. A fuel supply control device for an internal combustion engine.   The high-pressure pump control means includes a means for feedback-controlling a control amount of the fuel pressure control valve so as to reduce a deviation between a high-pressure side fuel pressure detected by the fuel pressure sensor and a target fuel pressure, and when the feedback control cannot be executed, The fuel for an internal combustion engine according to any one of claims 1 to 6, further comprising: open-loop control of a control amount of the fuel pressure control valve using a learning value stored in a storage means. Supply control device.

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