JP2009221906A - Low pressure pump control device of direct injection type internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption of a low pressure pump for a direct injection type engine which supplies a fuel from a fuel tank to a fuel injection valve via the low pressure pump and a high pressure pump. <P>SOLUTION: A basic duty is calculated according to an engine speed and a load, a first correction coefficient is calculated according to a valve closing time of a fuel control valve 23 of the high pressure pump 14, a second correction coefficient is calculated according to an opening of a relief valve 33 disposed on a delivery pipe 30 at the same time, and a drive voltage of the low pressure pump 12 is subject to duty control using a control duty obtained by correcting the basic duty with the first and second correction coefficients. A discharge rate of the low pressure pump 12 is accordingly controlled to an appropriate value (for example, a minimally required discharge rate) according to a fuel consumption amount, a discharge rate of the high pressure pump 14, and a return fuel amount returned from the delivery pipe 30 to the fuel tank 11, thereby reducing power consumption (power consumption especially in a low-load operation region) of the low pressure pump 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a low pressure pump control device for a direct injection internal combustion engine that supplies fuel in a fuel tank to a high pressure pump by a low pressure pump and supplies fuel discharged from the 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. Therefore, in a cylinder injection engine, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2006-220112), fuel pumped up from a fuel tank by an electric low-pressure pump is driven by a camshaft of the engine. The high-pressure pump is supplied to the high-pressure pump, and high-pressure fuel discharged from the high-pressure pump is pumped to the fuel injection valve of each cylinder through the high-pressure fuel pipe.

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. However, the low-pressure pump is driven under a certain condition (constant driving voltage), the pressure regulator regulates the discharge pressure of the low-pressure pump to a predetermined pressure, and surplus fuel exceeding that pressure is stored in the fuel tank. I'm trying to get it back.
JP 2006-220112 A

  In recent years, there has been an increasing demand for further improvement in fuel consumption. However, in a system that drives the low-pressure pump of a direct injection engine under constant conditions, the low-pressure pump is driven under the same conditions as in the operation region where the fuel consumption is high even in the operation region where the fuel consumption of the engine is low. In the operation region where the amount is small, the discharge amount of the low-pressure pump is excessive with respect to the fuel consumption amount and the discharge amount of the high-pressure pump, and the low-pressure pump is driven with a discharge amount more than necessary. For this reason, there is a problem that the battery power is wasted by the low-pressure pump, and the fuel consumption is reduced accordingly.

  The present invention has been made in consideration of such circumstances. Accordingly, an object of the present invention is to reduce the power consumption of the low-pressure pump and to satisfy the demand for improvement in fuel consumption. An object of the present invention is to provide a low-pressure pump control device for an internal combustion engine.

  In order to achieve the above object, the invention according to claim 1 supplies the fuel in the fuel tank to the high pressure pump by the low pressure pump, and supplies the fuel discharged from the high pressure pump to the fuel injection valve through the high pressure fuel passage. In the low pressure pump control device for a direct injection internal combustion engine, the low pressure pump is controlled by the low pressure pump control means in accordance with the operating state of the internal combustion engine. In this configuration, the discharge amount of the low pressure pump is changed according to the operating state of the internal combustion engine (for example, the fuel consumption, the discharge amount of the high pressure pump, the return fuel amount returned from the high pressure fuel passage to the fuel tank, etc.) The discharge amount of the pump can be controlled to an appropriate value (for example, the necessary minimum discharge amount) according to the operating state of the internal combustion engine. Thereby, the power consumption of a low pressure pump can be reduced and the request | requirement of a fuel consumption improvement can be satisfy | filled.

  In a cylinder injection internal combustion engine, the fuel discharged from the low pressure pump is supplied to the high pressure pump, and the fuel discharged from the high pressure pump is supplied to the fuel injection valve. The amount of fuel to be discharged by the high-pressure pump changes according to the amount), and the amount of fuel to be discharged by the low-pressure pump changes according to the discharge amount of the high-pressure pump.

  Therefore, as in claim 2, the low pressure pump may be controlled according to the control amount of the fuel pressure control valve for adjusting the discharge pressure of the high pressure pump. In this way, the discharge pressure (discharge amount) of the high-pressure pump changes according to the control amount of the fuel pressure control valve, and the discharge amount of the low-pressure pump is appropriately set according to the discharge amount of the fuel pressure control valve. Can be changed.

  Further, when the present invention is applied to a system having a relief valve for opening and closing a fuel return passage for returning the fuel in the high-pressure fuel passage to the fuel tank as in claim 3, the relief valve is brought into an open / closed state. The low pressure pump may be controlled accordingly. When the relief valve is open, the fuel in the high-pressure fuel passage discharged from the high-pressure pump is in the state of being returned to the fuel tank. It is considered that there is no adverse effect even if the amount of fuel supplied to is reduced. Therefore, if the low pressure pump is controlled according to the open / close state of the relief valve, the discharge amount of the low pressure pump is reduced when the relief valve is opened and the fuel discharged from the high pressure pump is returned to the fuel tank. Thus, the power consumption of the low-pressure pump can be reduced.

  Furthermore, when the relief valve is of an electromagnetic drive type that can control the open / close state as in claim 4, the low pressure pump may be controlled in accordance with the control amount of the relief valve. In this way, the discharge amount of the low-pressure pump is changed in response to the change in the amount of return fuel returned from the high-pressure fuel passage to the fuel tank in accordance with the control amount (for example, opening) of the relief valve. The pump discharge amount can be appropriately changed according to the return fuel amount.

  According to another aspect of the present invention, the amount of the return fuel returned to the fuel tank from the high pressure fuel passage and / or the high pressure pump is estimated or detected by the return fuel amount determination means, and the low pressure pump is controlled according to the return fuel amount. You may do it. In this way, the discharge amount of the low pressure pump is changed according to the amount of the return fuel returned from the high pressure fuel passage or the high pressure pump to the fuel tank, and the discharge amount of the low pressure pump is changed appropriately according to the return fuel amount. be able to.

  Further, as in claim 6, the low pressure pump may be controlled in accordance with the fuel consumption of the internal combustion engine or information correlated therewith. In this way, the discharge amount of the low pressure pump can be appropriately changed according to the fuel consumption amount in response to the change in the fuel amount to be discharged by the low pressure pump according to the fuel consumption amount of the internal combustion engine. it can.

  In this case, it is preferable to use at least one of the fuel injection amount of the internal combustion engine, the engine rotational speed, and the engine load as the information correlated with the fuel consumption amount. The total amount of fuel injection for all cylinders is the fuel consumption. Further, the fuel injection amount changes according to the rotational speed and load of the internal combustion engine, and the fuel consumption amount changes. Therefore, the fuel injection amount, engine rotation speed, and engine load of the internal combustion engine are information that accurately reflects the fuel consumption.

  Several embodiments embodying the best mode for carrying out the present invention will be described below.

A first embodiment of the present invention will be described with reference to FIGS.
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 pressure regulator 15 regulates the discharge pressure of the low-pressure pump 12 (fuel supply pressure to the high-pressure pump 14) to a predetermined 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 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 time of the fuel pressure control valve 23 (the valve closing time 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). To control.

  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 time 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 time 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 a delivery pipe 30 (high-pressure fuel passage) through a high-pressure fuel pipe 29 (high-pressure fuel passage), and a fuel injection valve attached to the upper part of each cylinder of the engine from the delivery pipe 30. The high-pressure fuel is distributed to 31. The delivery pipe 30 is provided with a fuel pressure sensor 32 that detects the fuel pressure (fuel pressure) in the delivery pipe 30.

  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 via a return pipe 34 (fuel return passage). Further, a branch pipe 35 branched from the return pipe 34 is connected to the pump chamber 18 of the high-pressure pump 14. The relief valve 33 is an electromagnetic drive type that can control the open / close state, and the fuel pressure in the delivery pipe 30 is held when the relief valve 33 is closed. When the relief valve 33 is opened, part of the fuel in the delivery pipe 30 is returned to the fuel tank 11 (or the pump chamber 18) through the return pipe 34, and the fuel pressure in the delivery pipe 30 is reduced.

  The engine is also provided with an air flow meter 36 that detects the intake air amount and a crank angle sensor 37 that outputs a crank angle signal pulse at every predetermined crank angle in synchronization with rotation of a crankshaft (not shown). ing. 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.

  At that time, the ECU 38 feedback controls the discharge amount of the high-pressure pump 14 (the closing time of the fuel pressure control valve 23) so that the fuel pressure in the delivery pipe 30 detected by the fuel pressure sensor 32 matches the target fuel pressure. Further, when the target fuel pressure is reduced (for example, when the deceleration fuel is cut or the engine is stopped), the relief valve 33 is opened and the fuel in the delivery pipe 30 is returned to the fuel tank 11 to return the fuel in the delivery pipe 30. Reduce fuel pressure.

  Further, the ECU 38 executes a low-pressure pump control routine of FIG. 2 described later, so that the engine operating state (for example, fuel consumption, discharge amount of the high-pressure pump 23, return fuel amount returned from the delivery pipe 30 to the fuel tank 11). Etc.), the control duty of the low-pressure pump 12 is calculated, and the discharge voltage of the low-pressure pump 12 is controlled by duty-controlling the drive voltage of the low-pressure pump 12 with this control duty. Thereby, the discharge amount of the low-pressure pump 12 is changed according to the engine operating state, and the discharge amount of the low-pressure pump 12 is controlled to an appropriate value (for example, the minimum required discharge amount) according to the engine operating state.

Hereinafter, the processing content of the low pressure pump control routine of FIG. 2 executed by the ECU 38 will be described.
The low-pressure pump control routine shown in FIG. 2 is executed at a predetermined cycle while the ECU 38 is powered on, and serves as a low-pressure pump control means in the claims. When this routine is started, first, in step 101, referring to the basic duty map shown in FIG. 3, the engine speed and engine load (for example, intake air amount, intake pipe pressure, throttle opening degree, etc.) are set. The corresponding basic duty is calculated.

  In general, the fuel consumption decreases as the engine speed decreases, and the fuel consumption decreases as the engine load decreases. Therefore, the basic duty map shown in FIG. 3 indicates that the basic duty is reduced and the control duty of the low-pressure pump 12 is reduced and the engine load is reduced as the engine speed is reduced and the fuel consumption is reduced. It is set so that the basic duty is reduced and the control duty of the low-pressure pump 12 is reduced as the fuel consumption is reduced. As a result, the lower the engine speed and the lower the fuel consumption, the lower the driving voltage of the low-pressure pump 12 and the lower the discharge amount of the low-pressure pump 12, and the lower the engine load and the lower the fuel consumption. The lower the drive voltage of the low-pressure pump 12, the lower the discharge amount of the low-pressure pump 12.

  Thereafter, the process proceeds to step 102, and the first correction coefficient corresponding to the valve closing time of the fuel pressure control valve 23 is calculated with reference to the map of the first correction coefficient shown in FIG.

  The map of the first correction coefficient shown in FIG. 4 shows that the first correction coefficient becomes smaller and the control of the low-pressure pump 12 as the valve closing time of the fuel pressure control valve 23 becomes shorter and the discharge amount of the high-pressure pump 13 decreases. The duty is set to be small. Thereby, the drive voltage of the low-pressure pump 12 decreases and the discharge amount of the low-pressure pump 12 decreases as the valve closing time of the fuel pressure control valve 23 becomes shorter and the discharge amount of the high-pressure pump 13 decreases. .

  The map of the first correction coefficient shown in FIG. 4 is set so that the first correction coefficient changes linearly with respect to the valve closing time of the fuel pressure control valve 23, but is not limited to this. For example, as shown by a broken line in FIG. 5, the first correction coefficient is set to change in a curve with respect to the valve closing time of the fuel pressure control valve 23, or as shown by a solid line in FIG. In addition, the first correction coefficient may be set to change stepwise with respect to the valve closing time of the fuel pressure control valve 23.

  Thereafter, the process proceeds to step 103, and a second correction coefficient corresponding to the opening degree of the relief valve 33 is calculated with reference to the second correction coefficient map shown in FIG.

  When the relief valve 33 is opened, the fuel in the delivery pipe 30 (that is, the fuel discharged from the high-pressure pump 23) is returned to the fuel tank 11, so that the discharge amount of the low-pressure pump 12 is reduced. Therefore, even if the amount of fuel supplied from the low pressure pump 12 to the high pressure pump 23 is reduced, it is considered that there is no adverse effect.

  Therefore, in the second correction coefficient map shown in FIG. 6, the second correction coefficient decreases as the opening degree of the relief valve 33 increases and the amount of return fuel returned from the delivery pipe 30 to the fuel tank 11 increases. Thus, the control duty of the low pressure pump 12 is set to be small. Thus, as the opening of the relief valve 33 increases and the amount of return fuel returned from the delivery pipe 30 to the fuel tank 11 increases, the drive voltage of the low-pressure pump 12 decreases and the discharge amount of the low-pressure pump 12 decreases. It has become.

  The second correction coefficient map shown in FIG. 6 is set so that the second correction coefficient changes linearly with respect to the opening degree of the relief valve 33, but the present invention is not limited to this. For example, The second correction coefficient is set so as to change in a curve with respect to the opening degree of the relief valve 33, or the second correction coefficient changes stepwise with respect to the opening degree of the relief valve 33. You may set as follows.

Thereafter, the process proceeds to step 104, where the basic duty is multiplied by the first correction coefficient and the second correction coefficient to correct the basic duty with the first correction coefficient and the second correction coefficient, and the final control is performed. Find the duty.
Control duty = basic duty × first correction coefficient × second correction coefficient Thereafter, the routine proceeds to step 105 where the drive voltage of the low-pressure pump 12 is duty-controlled with this control duty to control the discharge amount of the low-pressure pump 12.

  In the first embodiment described above, the basic duty is calculated according to the engine speed and the engine load, the first correction coefficient is calculated according to the closing time of the fuel pressure control valve 23, and the relief valve 33 is opened. The second correction coefficient is calculated according to the degree, the basic duty is corrected with the first correction coefficient and the second correction coefficient to obtain the final control duty, and the drive voltage of the low-pressure pump 12 is determined with this control duty. Duty control is performed to control the discharge amount of the low-pressure pump 12.

  As a result, the basic duty can be changed to change the discharge amount of the low-pressure pump 12 in response to the change in fuel consumption according to the engine speed and engine load, and the fuel pressure control valve 23 can be closed. The discharge amount of the low-pressure pump 12 can be corrected by changing the first correction coefficient in response to the change of the discharge amount of the high-pressure pump 14 according to the valve time, and also according to the opening degree of the relief valve 33. The discharge amount of the low-pressure pump 12 can be corrected by changing the second correction coefficient in response to the change in the amount of return fuel returned from the delivery pipe 30 to the fuel tank 11. The amount can be controlled to an appropriate value (for example, the minimum required discharge amount) according to the fuel consumption amount, the discharge amount of the high-pressure pump 14 and the return fuel amount. Thereby, the power consumption of the low-pressure pump 12 (especially the power consumption in the low load operation region where the fuel consumption is small) can be reduced, and the demand for improvement in fuel consumption can be satisfied.

  By the way, in a conventional system in which a low pressure pump is driven under a certain condition, if a low pressure pump (a pump having a large discharge amount) corresponding to an engine having a large displacement is used for an engine having a small displacement, a discharge amount in a low load region. Becomes excessive. Further, if a low pressure pump (a pump with a small discharge amount) corresponding to an engine with a small displacement is used for an engine with a large displacement, the discharge amount is insufficient in a high load region.

  On the other hand, in the system that controls the low-pressure pump 12 according to the engine operation state (fuel consumption, discharge amount of the high-pressure pump 14, return fuel amount, etc.) as in the first embodiment, an engine with a large displacement is used. When the corresponding low-pressure pump (pump with a large discharge amount) is used for an engine with a small displacement, the discharge amount becomes excessive by controlling the low-pressure pump to reduce the discharge amount of the low-pressure pump in a low load region. Can be prevented. This makes it possible to share the low-pressure pump 12 between an engine with a large displacement and an engine with a small displacement, and can meet the demand for cost reduction.

  Next, Embodiment 2 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the first embodiment, the first correction coefficient is calculated according to the valve closing time of the fuel pressure control valve 23, the second correction coefficient is calculated according to the opening degree of the relief valve 33, and the basic duty is set to the first. In this embodiment, the basic duty is corrected by the first correction coefficient and the second correction coefficient to obtain the final control duty. The first reduction correction amount is calculated according to the closing time of the fuel pressure control valve 23, the second reduction correction amount is calculated according to the opening of the relief valve 33, and the first reduction correction amount is calculated from the basic duty. By subtracting the amount and the second reduction correction amount, the basic duty is corrected by the first reduction correction amount and the second reduction correction amount to obtain the final control duty.

  Specifically, the first reduction correction amount corresponding to the valve closing time of the fuel pressure control valve 23 is calculated with reference to the first reduction correction amount map shown in FIG. The map of the first reduction correction amount shown in FIG. 7 shows that the first reduction correction amount increases as the valve closing time of the fuel pressure control valve 23 becomes shorter and the discharge amount of the high-pressure pump 13 decreases. The control duty is set to be small.

  Note that the map of the first reduction correction amount shown in FIG. 7 is set so that the first reduction correction amount changes linearly with respect to the valve closing time of the fuel pressure control valve 23, but this is not limitative. For example, the first reduction correction amount is set so as to change in a curve with respect to the valve closing time of the fuel pressure control valve 23, or is set to the first value with respect to the valve closing time of the fuel pressure control valve 23. The amount of decrease correction may be set to change stepwise.

  Thereafter, the second reduction correction amount corresponding to the opening degree of the relief valve 33 is calculated with reference to the map of the second reduction correction amount shown in FIG. The second reduction correction amount map shown in FIG. 8 indicates that the second reduction correction amount increases as the opening of the relief valve 33 increases and the amount of return fuel returned from the delivery pipe 30 to the fuel tank 11 increases. Thus, the control duty of the low pressure pump 12 is set to be small.

  Note that the second reduction correction amount map shown in FIG. 8 is set so that the second reduction correction amount changes linearly with respect to the opening of the relief valve 33, but is not limited thereto. For example, the second reduction amount correction amount is set so as to change in a curve with respect to the opening degree of the relief valve 33, or the second reduction amount correction amount is set to a step with respect to the opening degree of the relief valve 33. You may set so that it may change.

  Thereafter, by subtracting the first reduction correction amount and the second reduction correction amount from the basic duty, the basic duty is corrected by the first correction coefficient and the second correction coefficient to obtain the final control duty. .

      Control duty = (basic duty) − (first reduction correction amount + second reduction correction amount) In the second embodiment described above, the same effect as in the first embodiment can be obtained.

  In the first and second embodiments, the basic duty is calculated according to the engine speed and the engine load. However, the basic duty is calculated only according to one of the engine speed and the engine load. Anyway. Alternatively, the basic duty may be calculated according to the fuel injection amount. Since the total fuel injection amount of all cylinders is the fuel consumption amount, if the basic duty is calculated according to the fuel injection amount, the basic duty is set corresponding to the change in the fuel consumption amount according to the fuel injection amount. It is possible to change the discharge amount of the low-pressure pump 12.

  In the first and second embodiments, the control duty of the low-pressure pump 12 is corrected according to the opening degree of the electromagnetically driven relief valve 33. However, the fuel pressure in the delivery pipe 30 is not an electromagnetically driven type. In the case of a system including a mechanical relief valve that opens when the pressure exceeds a predetermined value, the control duty of the low-pressure pump 12 may be corrected when the relief valve opens.

  Further, the amount of the return fuel returned from the delivery pipe 30 to the fuel tank 11, the amount of the return fuel returned from the high-pressure pump 14 to the fuel tank 11, and the amount of the return fuel returned from both the delivery pipe 30 and the high-pressure pump 14 to the fuel tank 11. One of them may be estimated or detected, and the control duty of the low-pressure pump 12 may be corrected so that the amount of the lean fuel coincides with the target value.

  In the first and second embodiments, the control duty of the low-pressure pump 12 is changed according to all of the fuel consumption, the discharge amount of the high-pressure pump 14 and the return fuel amount. The control duty of the low pressure pump 12 may be changed according to any one or two of the 14 discharge amounts and the return fuel amount. Alternatively, the control duty of the low-pressure pump 12 may be changed according to the engine operating state other than the fuel consumption, the discharge amount of the high-pressure pump 14 and the return fuel amount.

  In each of the first and second embodiments, the present invention is applied to a system that controls the drive voltage of the low-pressure pump 12. However, the present invention is not limited to this, and the present invention is applied to a system that switches the drive voltage of the low-pressure pump 12 in a plurality of stages. The invention may be applied, and in this case, the driving voltage switching condition may be changed according to the engine operating state (fuel consumption, discharge amount of the high-pressure pump 14, return fuel amount, etc.).

It is a schematic block diagram of the whole fuel supply system in Example 1 of this invention. 3 is a flowchart illustrating a flow of processing of a low-pressure pump control routine according to the first embodiment. It is a figure which shows notionally an example of the map of the basic duty of Example 1. FIG. FIG. 3 is a diagram conceptually illustrating an example of a first correction coefficient map according to the first exemplary embodiment. FIG. 10 is a diagram conceptually illustrating another example of the first correction coefficient map of the first embodiment. FIG. 6 is a diagram conceptually illustrating an example of a second correction coefficient map according to the first exemplary embodiment. It is a figure which shows notionally an example of the map of the 1st reduction | decrease correction amount of Example 2. FIG. It is a figure which shows notionally an example of the map of the 2nd reduction | decrease correction amount of Example 2. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Fuel tank, 12 ... Low pressure pump, 14 ... High pressure pump, 18 ... Pump chamber, 19 ... Piston, 22 ... Suction port, 23 ... Fuel pressure control valve, 27 ... Discharge port, 29 ... High pressure fuel piping (high pressure fuel passage) , 30 ... Delivery pipe (high pressure fuel passage), 31 ... Fuel injection valve, 32 ... Fuel pressure sensor, 33 ... Relief valve, 34 ... Return pipe (fuel return passage), 38 ... ECU (low pressure pump control means)

Claims (7)

In a low-pressure pump control device for a direct injection internal combustion engine that supplies fuel in a fuel tank to a high-pressure pump by a low-pressure pump and supplies fuel discharged from the high-pressure pump to a fuel injection valve through a high-pressure fuel passage
A low-pressure pump control device for a direct injection internal combustion engine, comprising low-pressure pump control means for controlling the low-pressure pump in accordance with an operating state of the internal combustion engine.   The low-pressure pump control means controls the low-pressure pump in accordance with a control amount of a fuel pressure control valve that adjusts a discharge pressure of the high-pressure pump. Pump control device. A relief valve that opens and closes a fuel return passage for returning the fuel in the high-pressure fuel passage to the fuel tank;
The low-pressure pump control device for a direct injection internal combustion engine according to claim 1 or 2, wherein the low-pressure pump control means controls the low-pressure pump according to an open / close state of the relief valve. The relief valve is an electromagnetic drive type that can control the open / close state,
4. The low-pressure pump control device for a direct injection internal combustion engine according to claim 3, wherein the low-pressure pump control means controls the low-pressure pump according to a control amount of the relief valve. A retan fuel amount determining means for estimating or detecting a retan fuel amount returned from the high pressure fuel passage and / or the high pressure pump to the fuel tank;
The in-cylinder injection type according to any one of claims 1 to 4, wherein the low-pressure pump control means controls the low-pressure pump in accordance with a return fuel amount estimated or detected by the return fuel amount determination means. Low pressure pump control device for internal combustion engine.   The in-cylinder injection internal combustion engine according to any one of claims 1 to 5, wherein the low-pressure pump control means controls the low-pressure pump according to fuel consumption of the internal combustion engine or information correlated therewith. Low pressure pump control device. The low pressure of the direct injection internal combustion engine according to claim 6, wherein the information correlated with the fuel consumption is at least one of a fuel injection amount of the internal combustion engine, an engine rotation speed, and an engine load. Pump control device.
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