JP2008180169A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of inhibiting generation of fuel pressure pulsation in a low pressure fuel passage caused by volume change of pressurizing chamber of a high pressure fuel pump, while ensuring open and close action of a shut off valve of the high pressure fuel pump. <P>SOLUTION: When pressure feed quantity of the high pressure fuel pump 50 is below predetermined judgment quantity, ECU 70 controls pressure feed quantity of the high pressure fuel pump 50 by changing open period of the shut off valve 64 during volume increase of the pressurizing chamber 60. The shut off valve 64 is normally closed during volume decrease of the pressurizing chamber 60, and pulsation caused by the high pressure pump is inhibited from being generated in the low pressure passage since reverse flow to the low pressure fuel passages such as fuel passages 33, 35, 39 does not occur. Quantity of fuel sucked in the pressurizing chamber 60 from the low pressure fuel passage gets small in suction stroke, and force sucking a valve element 64a of the shut off valve 64 in an open direction also gets small. At that time, close action of the shut off valve 64 can be surely done. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for controlling an internal combustion engine, and in particular, a low pressure fuel injection device that injects fuel into an intake passage, a high pressure fuel injection device that directly injects fuel into a cylinder, and a fuel in the low pressure fuel injection device. The present invention relates to the control of an internal combustion engine including a high-pressure fuel pump that sucks fuel from a low-pressure fuel passage that supplies fuel and boosts the pressure to supply the fuel to a high-pressure fuel injection device.

  Some internal combustion engines include both a low-pressure fuel injection device that injects fuel into an intake passage and a high-pressure fuel injection device that injects fuel into a cylinder in order to achieve both reduction in fuel consumption and high output. In such an internal combustion engine, a low-pressure fuel injection device and a high-pressure fuel injection device are used in combination or selectively according to the operating state, thereby reducing fuel consumption at low loads and improving anti-knock performance at high loads. ing.

  Such an internal combustion engine usually has a fuel pump (hereinafter referred to as a low-pressure fuel pump) that pumps fuel from a fuel tank and pumps it, and a fuel pump (hereinafter referred to as a low-pressure fuel pump) that further boosts the pressure of the fuel pumped from the low-pressure fuel pump. , Referred to as a high-pressure fuel pump). The low-pressure fuel pump pumps low-pressure (for example, 0.4 MPa) fuel from the fuel tank to a fuel passage (hereinafter referred to as a low-pressure fuel passage) that communicates with the low-pressure fuel injection device. In this way, the low pressure fuel injection device can receive fuel supplied from the low pressure fuel passage and inject low pressure fuel into the intake passage. The low pressure fuel passage communicates not only with the low pressure fuel injection device but also with the high pressure fuel pump.

  The high-pressure fuel pump sucks low-pressure fuel from a low-pressure fuel passage, boosts the pressure inside, and supplies high-pressure (for example, 10 MPa) fuel to a fuel passage (hereinafter referred to as a high-pressure fuel passage) communicating with a high-pressure fuel injection device. Pump. In this way, the high pressure fuel injection device receives the supply of high pressure fuel from the high pressure fuel passage and injects the fuel directly into the cylinder.

  Such a high-pressure fuel pump is provided between a pressurization chamber whose volume changes periodically according to the operating state of the internal combustion engine, and between the low-pressure fuel passage and the pressurization chamber, and opens and closes the valve body. It has a shut-off valve that can switch communication / cut-off between the low-pressure fuel passage and the pressurization chamber by operation, and the fuel that is sucked into the pressurization chamber from the low-pressure fuel passage by increasing the volume of the pressurization chamber Is known to increase the pressure of the pressure chamber by reducing the volume of the pressurizing chamber and pump it to the high pressure fuel passage (see, for example, Patent Document 1).

  In the high-pressure fuel pump described in Patent Document 1 below, the pressurizing chamber is defined by a cylinder hole formed inside the high-pressure fuel pump and a plunger that is driven by the rotation of the cam to reciprocate within the cylinder hole. An electromagnetic on-off valve (shutoff valve) is provided between the pressurizing chamber and the low-pressure fuel passage for metering the fuel sucked into the pressurizing chamber. The electromagnetic open / close valve is controlled to open and close by an electronic control unit (ECU) for an internal combustion engine.

  In addition, Patent Document 1 discloses mainly the following two control methods as a method for controlling the amount of fuel pumped from the high-pressure fuel pump to the high-pressure fuel passage (hereinafter referred to as a pumping amount). . One is that when the volume of the pressurizing chamber is increasing (hereinafter referred to as “when the volume is increasing”), the shutoff valve is opened for a predetermined period of time to suck into the pressurizing chamber from the low pressure fuel passage. When the amount of fuel is adjusted and the volume of the pressurizing chamber is decreasing (hereinafter referred to as volume decreasing), the shut-off valve is always closed to boost the intake fuel in the pressurizing chamber. This is a technique of pumping to the high pressure fuel passage. In this control method, the pumping amount of the high-pressure fuel pump is controlled by changing the opening period of the shutoff valve when the volume of the pressurizing chamber is increased.

  The other is that when the volume of the pressurizing chamber is increased, the shut-off valve is always opened, and fuel is sucked into the pressurizing chamber from the low-pressure fuel passage. By closing the valve, a predetermined amount of fuel flows backward from the pressurizing chamber to the low pressure fuel passage before the valve is closed, and then the fuel remaining in the pressurizing chamber is pumped to the high pressure fuel passage when the valve is closed. It is a technique. In this control method, the pumping amount of the high-pressure fuel pump is controlled by changing the closing period of the shut-off valve when the volume of the pressurizing chamber is decreased.

JP 2005-146882 A

  By the way, in the control method for controlling the pumping amount of the high-pressure fuel pump by changing the closing period of the shut-off valve when the volume of the pressurizing chamber is decreased (hereinafter referred to as pumping metering control), when the volume of the pressurizing chamber is decreased In FIG. 3, a back flow occurs from the pressurizing chamber to the low pressure fuel passage. Such a reverse flow is periodically generated in accordance with the volume change of the pressurizing chamber, that is, the operation of the high-pressure fuel pump. When control is performed to reduce the pumping amount of the high-pressure fuel pump, such as when the internal combustion engine is idling, the amount of fuel flowing back from the high-pressure fuel pump to the low-pressure fuel passage increases accordingly.

  In this way, when the amount of fuel flowing back from the high-pressure fuel pump to the low-pressure fuel passage is large, fuel pressure pulsations that are periodic fluctuations in fuel pressure occur in the low-pressure fuel passage. The fuel pressure pulsation generated in the low pressure fuel passage due to the operation of the high pressure fuel pump is simply referred to as “high pressure pump induced pulsation” in the following description. On the other hand, the fuel pressure pulsation generated in the low-pressure fuel passage due to the fuel injection of the low-pressure fuel injection device is distinguished by simply being referred to as “fuel injection-induced pulsation”. FIG. 6 shows an example of the fuel pressure pulsation in the low pressure fuel passage when the fuel injection pulsation and the high pressure pump pulsation occur simultaneously. The high-pressure pump-induced pulsation is generated according to the volume change of the pressurizing chamber, and as shown in FIG. 6, the cycle tends to be extremely long compared to the fuel injection pulsation.

  In this way, when a pulsation caused by a high-pressure pump with a long cycle occurs in the low-pressure fuel passage, in the low-pressure fuel injection device that receives the direct supply of fuel from the low-pressure fuel passage, the injection amount actually injected is the predetermined fuel injection amount. Can not do. Further, if the period of pulsation caused by the high-pressure pump is long, the injection amount actually injected by the low-pressure fuel injection device may vary between different cylinders. As described above, when the fuel injection amount of the low-pressure fuel injection device is deviated from a predetermined value or varies between different cylinders, harmful components in the exhaust gas may increase or the output of the internal combustion engine may decrease. is there.

  On the other hand, in the control method (hereinafter referred to as intake metering control) that controls the pumping amount of the high-pressure fuel pump by changing the opening period of the shut-off valve when the volume of the pressurizing chamber increases, when the volume of the pressurizing chamber decreases In FIG. 5, the shut-off valve is always closed. For this reason, in the intake metering control, there is no back flow from the pressurizing chamber to the low pressure fuel passage.

  However, in the intake metering control, in order to adjust the pumping amount of the high pressure fuel pump, it is necessary to open and close the shutoff valve when the volume of the pressurizing chamber is increased, that is, when the pressurizing chamber is depressurized. In order to close the shut-off valve while the fuel is flowing from the low pressure fuel passage into the pressurizing chamber, the fuel sucked in the direction in which the valve element is opened by the fuel flowing into the pressurizing chamber is exceeded. It is necessary to drive the valve body in the closing direction. In particular, when the pumping amount of the high-pressure fuel pump is large, that is, when the amount of fuel sucked into the pressurizing chamber is large, the force that the valve body is sucked in the valve opening direction becomes large, and the valve body is adjusted to exceed this force. Driving in the valve closing direction is disadvantageous in that the shutoff valve is reliably opened and closed.

  The present invention has been made in view of the above, and fuel pressure pulsation caused by a change in the volume of the pressurizing chamber of the high-pressure fuel pump is generated in the low-pressure fuel passage while ensuring the opening and closing operation of the shutoff valve of the high-pressure fuel pump. An object of the present invention is to provide a control device for an internal combustion engine capable of suppressing the occurrence.

  In order to achieve the above object, an internal combustion engine control apparatus according to the present invention includes a low-pressure fuel injection device that receives fuel from a low-pressure fuel passage and injects fuel into an intake passage, and a fuel supply from the high-pressure fuel passage. High pressure fuel injection device that receives fuel and injects fuel into the cylinder, pressurization chamber whose volume changes periodically, and communication between the low pressure fuel passage and pressurization chamber can be switched by opening and closing the valve body High pressure pressure that can be pumped into the high pressure fuel passage by increasing the volume of the pressurization chamber and sucking fuel from the low pressure fuel passage into the pressurization chamber. A control device for an internal combustion engine comprising a fuel pump, and a pressure adjustment amount control means for controlling a pumping amount of the high pressure fuel pump by changing a closing period of the shut-off valve when the volume of the pressurizing chamber is reduced; The opening period of the shut-off valve when the volume of the pressure chamber increases And a suction metering control means for controlling the pumping amount of the high-pressure fuel pump, and when the pumping amount of the high-pressure fuel pump falls below a predetermined judgment amount, It is characterized by controlling the amount.

  In the control device for an internal combustion engine according to the present invention, the pressurizing chamber may have a volume that changes at a frequency proportional to the engine rotation speed, and when the engine rotation speed exceeds a predetermined determination rotation speed, Regardless of the pumping amount of the high-pressure fuel pump, the pumping amount control means can control the pumping amount of the high-pressure fuel pump.

  In the control apparatus for an internal combustion engine according to the present invention, the shut-off valve is opened by energizing the valve body by the energizing force of the spring, and is closed by driving the valve body by the electromagnetic force generated by energizing the electromagnetic coil. When the pumping amount of the high pressure fuel pump is controlled by the suction metering control means, the energization amount of the electromagnetic coil when the volume of the pressurizing chamber is increased is the electromagnetic coil when the volume of the pressurizing chamber is decreased. It can be set to be larger than the energization amount.

  In the control device for an internal combustion engine according to the present invention, when the pumping amount of the high-pressure fuel pump is controlled by the intake metering control means, the opening period of the shut-off valve is the end point when the volume of the pressurizing chamber becomes maximum The initial period can be set to change according to the pumping amount of the high-pressure fuel pump.

  In the control device for an internal combustion engine according to the present invention, the high-pressure fuel pump includes a pump cam that is rotationally driven by receiving mechanical power from the crankshaft of the internal combustion engine, and a reciprocating motion within the cylinder hole that is driven by the pump cam. And the pressurizing chamber may be formed by being partitioned by a cylinder hole and a plunger, and the volume of the pressurizing chamber is determined by the rotation of the pump cam. It can be changed according to the increase or decrease of the lift amount.

  According to the present invention, when the pumping amount of the high pressure fuel pump is less than the predetermined determination amount, the suction metering control means for changing the valve opening period of the shut-off valve when the volume of the pressurizing chamber is increased is used. The pumping amount was controlled. If the high-pressure fuel pump has a small amount of pumping and pressure-feeding control is performed, even if a large amount of fuel backflow occurs in the low-pressure fuel passage when the volume of the pressurizing chamber is reduced, When the volume of the pressure chamber is reduced, the shut-off valve is always closed to prevent the backflow in the low pressure fuel passage, and the occurrence of pulsation caused by the high pressure pump in the low pressure fuel passage can be suppressed. In addition, since the intake metering control is performed only when the pumping amount of the high-pressure fuel pump is smaller than the predetermined determination amount, the amount of fuel sucked into the pressurizing chamber from the low-pressure fuel passage becomes small in the suction stroke, and the shut-off valve Since the force with which the valve body is sucked in the valve opening direction becomes small, the shut-off valve can be reliably closed at this time.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  First, a schematic configuration of the internal combustion engine according to the present embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view showing a schematic configuration around a cylinder of an internal combustion engine. FIG. 2 is a schematic diagram showing a schematic configuration of an engine system including an internal combustion engine. In FIGS. 1 and 2, for the internal combustion engine and the fuel supply device, only the main parts related to the present invention are schematically shown. The internal combustion engine according to this embodiment is mounted on a motor vehicle as a prime mover, and the motor vehicle includes an electronic control device for controlling an engine system including a fuel injection device, a high pressure fuel pump, and a low pressure fuel pump, which will be described later. (Hereinafter referred to as ECU).

  As shown in FIG. 1, an internal combustion engine 10 includes a low-pressure fuel injection device 30 that injects low-pressure (for example, 0.4 MPa) fuel into an intake passage as a fuel injection device that supplies fuel to a cylinder, A high-pressure fuel injection device 40 that injects high-pressure (for example, 10 MPa) fuel is provided for each cylinder.

  The “cylinder” is a space surrounded by the cylinder wall 15 of the cylinder block 14, the ceiling wall 22 of the cylinder head 20, and the top surface 28 (including the cavity wall 28 c) of the piston 27. The cylinder includes a combustion chamber 21 formed in the cylinder head 20 and a cavity formed in the piston 27.

  The “intake passage” means an air flow path through which air introduced from an outside air duct (not shown) passes into the cylinder. In this embodiment, the intake passage includes an intake manifold (not shown). In addition to the surge chamber and the branch passage, an intake port 24 of the cylinder head 20 is included.

  The low-pressure fuel injection device 30 is an electromagnetic fuel injection valve, and the injection period, that is, the valve opening timing and the valve opening time length are controlled by the ECU 70. The low pressure fuel injection device 30 is provided in an intake port formed in the cylinder head 20, and an injection hole is exposed to the intake port 24. When the low pressure fuel injection device 30 injects fuel into the intake passage, the injected fuel flows from the intake port 24 through the intake valve 25 into the cylinder.

  The high-pressure fuel injection device 40 is an electromagnetic or piezo-type fuel injection valve, and the injection period is controlled by the ECU 70. The high-pressure fuel injection device 40 is provided on the ceiling wall 22 of the combustion chamber 21 formed in the cylinder head 20, and the injection hole is exposed to the combustion chamber 21. When the high pressure fuel injection device 40 injects fuel into the combustion chamber 21, the injected fuel forms an air-fuel mixture in the cylinder.

  As shown in FIG. 2, the internal combustion engine 10 is provided with a crank angle sensor 72 that detects a rotational angle position (hereinafter referred to as a crank angle) of a crankshaft (not shown), and sends a signal related to the crank angle to the ECU 70. Sending out. The internal combustion engine 10 is provided with an air flow meter 74 that detects the flow rate of the intake air (hereinafter referred to as intake air amount), and sends a signal related to the intake air amount to the ECU 70. An automobile (not shown) on which the internal combustion engine 10 is mounted is provided with an accelerator position sensor 76 (not shown) that detects an operation amount (hereinafter referred to as an accelerator operation amount) of an accelerator pedal operated by a driver. Therefore, a signal related to the accelerator operation amount is sent to the ECU 70.

  Further, as shown in FIG. 2, the automobile on which the internal combustion engine 10 is mounted is provided with a fuel tank 80 that stores the fuel injected by the fuel injection devices 30 and 40 described above. The fuel tank 80 is a part for supplying the fuel in the fuel tank 80 to the internal combustion engine 10 at a predetermined fuel pressure, and a low-pressure fuel pump 82 that is a pump that pumps up and pumps the fuel, and dust contained in the fuel is removed. A fuel filter 84 and a pressure regulating valve (pressure regulator) 86 that adjusts the pressure of fuel pumped from the low-pressure fuel pump 82 are provided.

  In the fuel tank 80, a fuel filter 84 is provided on the downstream side in the fuel flow direction of the low-pressure fuel pump 82, and a pressure regulating valve 86 is provided on the downstream side of the fuel filter 84. Connected to the pressure regulating valve 86 are a vehicle body fuel pipe 90 for supplying fuel toward the internal combustion engine 10 and a return pipe 92 for returning excess fuel to the fuel tank 80 again.

  The low-pressure fuel pump 82 is an electric fuel pump that pumps up fuel in the fuel tank 80 and pumps it toward the internal combustion engine 10. The ECU 70 controls the operation / non-operation of the low-pressure fuel pump 82 and the ability to pump fuel.

  The pressure regulating valve 86 is divided into a housing and a diaphragm (not shown) to form a fuel chamber into which the fuel to be attenuated flows, and a spring (not shown) expands and contracts due to the pressure of the fuel flowing into the fuel chamber. Then, the valve element opens and moves when the diaphragm is bent. The pressure regulating valve 86 opens the valve body when the fuel pressure in the fuel chamber exceeds a predetermined pressure, and guides excess fuel to the return pipe 92. In this manner, the pressure regulating valve 86 can regulate the fuel pressure in the fuel chamber and the fuel passage communicating with the fuel chamber to a predetermined pressure (for example, 0.4 MPa).

  The fuel pumped up by the low-pressure fuel pump 82 is sent to the pressure regulating valve 86 after the dust contained in the fuel is removed by the fuel filter 84. The pressure regulating valve 86 returns the excess fuel that is not consumed by the fuel injection devices 30 and 40 from the fuel pumped up by the low-pressure fuel pump 82 from the return pipe 92 to the fuel tank 80 again. The pressure regulating valve 86 adjusts the fuel pressure of the low-pressure fuel pump 82 to a predetermined pressure and causes the fuel to flow through the vehicle body fuel pipe 90. The vehicle body fuel pipe 90 is connected to a low-pressure fuel pipe 34 described later provided in the engine room of the internal combustion engine 10.

  The internal combustion engine 10 has a low-pressure fuel rail that distributes fuel to the low-pressure fuel injector 30 as a low-pressure fuel system component for supplying fuel from the low-pressure fuel pump 82 to the low-pressure fuel injector 30 and the high-pressure fuel pump 50. 32, a low-pressure fuel pipe 34 that guides fuel from the vehicle body fuel pipe 90 to the low-pressure fuel rail 32 and a high-pressure fuel pump 50 described later, and a pulsation damper that attenuates fuel pressure pulsations generated in the low-pressure fuel pipe 34 and the low-pressure fuel rail 32. 36 and 38 are provided.

  The low-pressure fuel rail 32 is a metallic tubular member, and is connected to a low-pressure fuel injection device 30 provided for each cylinder. A pressure accumulation chamber 33 is formed inside the low pressure fuel rail 32, and the pressure accumulation chamber 33 and a nozzle hole (not shown) of the low pressure fuel injection device 30 communicate with each other. A low-pressure fuel pipe 34 to be described later is connected to one end of the low-pressure fuel rail 32, and a pressure accumulation chamber 33 of the low-pressure fuel rail 32 and a fuel passage 35 formed in the low-pressure fuel pipe 34 communicate with each other. The low-pressure fuel rail 32 distributes and supplies low-pressure fuel that has flowed from the low-pressure fuel pump 82 through the vehicle body fuel pipe 90 and the low-pressure fuel pipe 34 to the low-pressure fuel injection devices 30.

  The low-pressure fuel pipe 34 is configured by connecting a plurality of metal pipes, resin hoses and the like provided in the engine room, and a fuel passage 35 through which low-pressure fuel flows is formed. ing. One end of the low-pressure fuel pipe 34 is connected to the vehicle body fuel pipe 90 and the other end is connected to the low-pressure fuel rail 32, and a high-pressure fuel pump 50 described later is connected in the middle. The fuel passage 35 communicates a pressure regulating valve 86 in the fuel tank 80, a fuel passage 39 upstream of a shut-off valve 64 (described later) in the high-pressure fuel pump 50, and a pressure accumulating chamber 33 in the low-pressure fuel rail 32. Yes. The low pressure fuel pipe 34 is pumped by the low pressure fuel pump 82 in the fuel tank 80 and guides the low pressure fuel regulated by the pressure regulating valve 86 to the high pressure fuel pump 50 and the low pressure fuel rail 32.

  The pulsation dampers 36 and 38 (hereinafter simply referred to as “dampers”) are partitioned by a housing and a diaphragm (not shown) to form fuel chambers 36c and 38c into which fuel to be damped flows. . The dampers 36 and 38 and springs (not shown) expand and contract, the diaphragm bends, and the volume of the fuel chambers 36c and 38c is changed, so that fuel pressure pulsation, which is fuel pressure fluctuation, can be suppressed.

  In the present embodiment, the dampers 36 and 38 are provided corresponding to portions 34 c of the low pressure fuel rail 32 and the low pressure fuel pipe 34 that branch to the high pressure fuel pump 50. The damper 36 provided on the low-pressure fuel rail 32 has its frequency characteristics set so as to mainly attenuate fuel pressure pulsations generated in the low-pressure fuel passage by the valve opening and closing operations of the low-pressure fuel injector 30. On the other hand, the damper 38 provided in the vicinity of the high-pressure fuel pump 50 has its frequency characteristics set so as to mainly attenuate the fuel pressure pulsation generated in the low-pressure fuel passage due to the back flow from the high-pressure fuel pump 50.

  The “low pressure fuel passage” means a fuel flow path through which the fuel regulated by the pressure regulating valve 86 flows. In the present embodiment, the low pressure fuel passage includes, in addition to the fuel passage 91 in the vehicle body fuel pipe 90 and the fuel passage 35 in the low pressure fuel pipe 34, the pressure accumulating chamber 33 in the low pressure fuel rail 32 and the dampers 36 and 38. Fuel chambers 36c and 38c are included.

  The internal combustion engine 10 distributes fuel to each high-pressure fuel injector 40 as a high-pressure fuel system component for further boosting the pressure of the fuel supplied from the low-pressure fuel pipe 34 and supplying the fuel to the high-pressure fuel injector 40. A high-pressure fuel rail 44, a high-pressure fuel pump 50 that pressurizes and pressurizes low-pressure fuel from the low-pressure fuel pipe 34, and a high-pressure fuel pipe 46 that flows high-pressure fuel from the high-pressure fuel pump 50 to the high-pressure fuel rail 44 are provided. ing.

  The high-pressure fuel rail 44 is a metal tubular member, to which each high-pressure fuel injection device 40 provided for each cylinder is connected. A pressure accumulating chamber 45 is formed inside the high pressure fuel rail 44, and the pressure accumulating chamber 45 communicates with the nozzle holes of the high pressure fuel injection devices 40. A high pressure fuel pipe 46 is connected to one end of the high pressure fuel rail 44, and a pressure accumulation chamber 45 of the high pressure fuel rail 44 and a fuel passage 47 in the high pressure fuel pipe 46 communicate with each other. The high-pressure fuel rail 44 distributes and supplies the high-pressure fuel from the high-pressure fuel pump 50 to each high-pressure fuel injection device 40.

  The high-pressure fuel pipe 46 is constituted by a metal pipe provided in the internal combustion engine 10, and a fuel passage 47 through which fuel flows is formed. One end of the high-pressure fuel pipe 46 is connected to a check valve 51 described later of the high-pressure fuel pump 50, and the other end is connected to the high-pressure fuel rail 44. The high-pressure fuel pipe 46 communicates the check valve 51 of the high-pressure fuel pump 50 and the pressure accumulation chamber 45 of the high-pressure fuel rail 44. The high pressure fuel pipe 46 guides the high pressure fuel boosted by the high pressure fuel pump 50 to the high pressure fuel rail 44.

  The “high pressure fuel passage” means a fuel flow path through which high pressure fuel pressurized by the high pressure fuel pump 50 flows. In this embodiment, the high pressure fuel passage includes a pressure accumulation chamber 45 in the high pressure fuel rail 44 in addition to the fuel passage 47 in the high pressure fuel pipe 46.

  The high-pressure fuel pump 50 has a cylinder hole 52 formed therein. A plunger 54 that reciprocates in the cylinder hole 52, a pump cam 56 that drives the plunger 54, and the plunger 54 on the pump cam 56 side. It is composed of a spring 58 or the like for biasing. The high-pressure fuel pump 50 is formed with a pressurizing chamber 60 that is partitioned by a cylinder hole 52 and a plunger 54 and pressurizes the fuel.

  In the high-pressure fuel pump 50, the pump cam 56 is coupled to a camshaft (not shown) that drives an intake valve or an exhaust valve, and this camshaft is connected to a crankshaft (not shown) of the internal combustion engine 10. Driven by the mechanical power of Therefore, the pump cam 56 rotates at a speed twice that of the crankshaft of the internal combustion engine 10. In this embodiment, the cam for the pump 56 is formed with three cam peaks (cam noses) 56a.

  In the high-pressure fuel pump 50, the plunger 54 reciprocates along the axis of the cylinder hole 52 by the rotation of the pump cam 56. The high pressure fuel pump 50 increases or decreases the volume of the pressurizing chamber 60 by the reciprocating motion of the plunger 54. That is, the volume of the pressurizing chamber 60 changes periodically according to the rotational speed of the pump cam 56.

  In the present embodiment, the volume of the pressurizing chamber 60 increases and decreases by three cycles as the plunger reciprocates three times per rotation of the pump cam 56. Since the pump cam 56 rotates at a rotational speed twice that of the crankshaft of the internal combustion engine (hereinafter referred to as engine rotational speed), the pressurizing chamber 60 has a frequency six times the engine rotational speed. The volume will change periodically. The pressurizing chamber 60 is provided with a suction port 62 that communicates with the low-pressure fuel passage and sucks fuel from the low-pressure fuel passage.

  The high-pressure fuel pump 50 is provided with a shut-off valve 64 that switches between opening and closing of the suction port 62 between the low-pressure fuel passage and the pressurizing chamber 60. The shut-off valve 64 is an electromagnetic open / close valve, and a valve body 64a that opens / closes the suction port 62, and a direction in which the suction port 62 is opened by the electromagnetic force generated by energization (hereinafter referred to as opening). The electromagnetic coil 66 is driven in the direction of the valve), and a spring 67 that biases the valve body 64a in the direction in which the suction port 62 is closed (hereinafter referred to as the valve closing direction).

  When the solenoid coil 66 is not energized, the shut-off valve 64 urges the valve body 64 a toward the plunger 54 by the urging force of the spring 67 to open the suction port 62. That is, the shutoff valve 64 is opened so that the low pressure fuel passage and the pressurizing chamber 60 communicate with each other when the electromagnetic coil 66 is not energized. On the other hand, in the shutoff valve 64, when a predetermined current is applied to the electromagnetic coil 66, the valve body 64a is driven to the side opposite to the plunger 54 side by the electromagnetic force generated by the electromagnetic coil 66, and the suction port 62 is opened. Closed. That is, the shutoff valve 64 is closed so that the low pressure fuel passage and the pressurizing chamber 60 are shut off when the electromagnetic coil 66 is energized. The energization period of the electromagnetic coil 66, that is, the closing period of the shut-off valve 64 is controlled by the ECU 70. In this manner, the ECU 70 can perform control so as to switch between communication and blocking between the low pressure fuel passage and the pressurizing chamber 60 by the opening / closing operation of the blocking valve 64.

  The energization amount of the electromagnetic coil 66 when the shut-off valve 64 is closed is such that the force by which the electromagnetic coil 66 drives the valve body 64a in the valve closing direction is the urging force of the spring 67 and the pressurizing chamber 60 from the suction port 62. The valve body 64a is set so as to resist the force that the valve body 64a is sucked in the valve opening direction by the flow of the fuel flowing into the valve.

  In addition, a discharge port 69 for discharging fuel toward the high pressure fuel passage is formed in the pressurizing chamber 60 of the high pressure fuel pump 50. In addition, a check valve 51 is provided between the discharge port 69 of the high-pressure fuel pump 50 and the high-pressure fuel pipe 46 to prevent fuel backflow. The check valve 51 is a so-called check valve, and opens when the fuel from the discharge port 69 exceeds a predetermined valve opening pressure, and flows the fuel from the discharge port 69 into the high-pressure fuel passage. Thus, the check valve 51 prevents the fuel pressure-fed from the pressurizing chamber 60 through the discharge port 69 to the high-pressure fuel passage in the high-pressure fuel pipe 46 from flowing back into the pressurizing chamber 60 again. .

  When the internal combustion engine 10 operates and the pump cam 56 rotates and the cam crest 56 a pushes up the plunger 54, the high pressure fuel pump 50 moves in the direction in which the plunger 54 decreases the volume of the pressurizing chamber 60. In the following description, the movement of the plunger 54 in the direction of decreasing the volume of the pressurizing chamber 60 is referred to as “lift”, and the movement amount is referred to as “lift amount”. That is, in the high-pressure fuel pump 50, the volume of the pressurizing chamber 60 increases as the lift amount of the plunger 54 decreases.

  Further, the high-pressure fuel pump 50 is configured such that when the lift amount of the plunger 54 is decreased (hereinafter referred to as a lift amount decrease), that is, when the volume of the pressurizing chamber 60 is increased (hereinafter referred to as a volume increase). In addition, by opening the shut-off valve 64 and connecting the low-pressure fuel passage and the pressurizing chamber 60, the fuel in the low-pressure fuel passage can be sucked into the pressurizing chamber 60.

  Further, the high-pressure fuel pump 50 is described when the lift amount of the plunger 54 is increasing (hereinafter referred to as an increase in lift amount), that is, when the volume of the pressurizing chamber 60 is decreasing (hereinafter referred to as a decrease in volume). ), The fuel in the pressurizing chamber 60 can be pressurized by closing the shutoff valve 64 to shut off the low pressure fuel passage and the pressurizing chamber 60. The high-pressure fuel pump 50 can pump fuel from the check valve 51 to the high-pressure fuel passage by increasing the fuel in the pressurizing chamber 60 to a pressure higher than the opening pressure of the check valve 51.

  In the high-pressure fuel pump 50 configured as described above, the flow rate of fuel pumped from the high-pressure fuel pump 50 to the high-pressure fuel passage (hereinafter referred to as pumping amount) is such that the shutoff valve 64 is closed when the lift amount of the plunger 54 is increased. It can be controlled by changing the valve period. As the valve closing period of the shutoff valve 64 when the lift amount is increased is set longer, the pumping amount of the high-pressure fuel pump 50 can be increased. Further, by setting the valve opening period of the shutoff valve 64 to be long when the lift amount of the plunger 54 is reduced, the amount of fuel that the high pressure fuel pump 50 sucks into the pressurizing chamber 60 from the low pressure fuel passage can be increased. The opening / closing operation of the shutoff valve 64 is controlled by the ECU 70.

  The ECU 70 receives a signal related to the crank angle from the crank angle sensor 72, a signal related to the intake air amount from the air flow meter 74, and a signal related to the accelerator operation amount from the accelerator position sensor 76. Based on these detected various signals, the ECU 70 calculates a crank angle, an intake air amount, an accelerator operation amount, a target air-fuel ratio, and the like, and further, from these control variables, rotates the crankshaft of the internal combustion engine 10. A speed (hereinafter referred to as engine rotational speed), a torque output from the internal combustion engine 10 (hereinafter referred to as engine load), and the like are calculated.

  The ECU 70 determines the combined use or selective use of the low pressure fuel injection device 30 and the high pressure fuel injection device 40 according to the engine speed, the engine load, the target air-fuel ratio, and the like. The ECU 70 calculates a fuel injection amount for each of the low pressure fuel injection device 30 and the high pressure fuel injection device 40, and determines a fuel injection period, that is, a valve opening timing and a valve opening time length of the fuel injection device.

  Further, when the high pressure fuel injection device 40 is operated, the ECU 70 calculates a pumping amount required for the high pressure fuel pump 50 from the fuel injection amount injected by the high pressure fuel injection device 40. The ECU 70 determines the valve opening period (valve opening time and valve opening time length) of the shut-off valve 64 from the calculated pumping amount, that is, the energization period (energization time and energization time length) of the electromagnetic coil 66. The energization of the electromagnetic coil 66 is controlled so as to realize the above. In addition, the ECU 70 can control a current value (hereinafter referred to as an energization amount) for energizing the electromagnetic coil 66.

  Thus, the ECU 70 can control the pumping amount of the high-pressure fuel pump 50 by controlling the energizing period and the energizing amount of the electromagnetic coil 66 and causing the shut-off valve 64 to open and close. The ECU 70 can control the pumping amount of the high-pressure fuel pump 50 by the following two methods.

  One is a method of controlling the pumping amount of the high-pressure fuel pump by changing the closing period of the shutoff valve 64 when the volume of the pressurizing chamber 60 is reduced (hereinafter referred to as pumping control amount control). When the volume of the pressurizing chamber 60 increases, the ECU 70 always opens the shut-off valve 64 and sucks fuel into the pressurizing chamber 60 from the low pressure fuel passage. Then, when the volume of the pressurizing chamber 60 is reduced, the ECU 70 closes the shutoff valve 64 for a predetermined period, thereby causing a predetermined amount of fuel to flow backward from the pressurizing chamber 60 to the low-pressure fuel passage before closing. When the valve is closed, the fuel remaining in the pressurizing chamber 60 is pumped to the high pressure fuel passage. The pumping amount of the high-pressure fuel pump 50 can be changed according to the valve closing period including the valve closing time length of the shutoff valve 64 when the volume of the pressurizing chamber 60 is decreased. Thus, the ECU 70 has a function of controlling the pumping amount of the high-pressure fuel pump 50 to a desired value by changing the closing period of the shutoff valve 64 when the volume of the pressurizing chamber 60 is decreased. It has a control means.

  The other is a method of controlling the pumping amount of the high-pressure fuel pump 50 by changing the valve opening period of the shutoff valve 64 when the volume of the pressurizing chamber 60 is increased (hereinafter referred to as intake metering control). When the volume of the pressurizing chamber 60 of the high-pressure fuel pump 50 is increased, the ECU 70 adjusts the amount of fuel drawn into the pressurizing chamber 60 from the low-pressure fuel passage by opening the shut-off valve 64 for a predetermined period. The ECU 70 always closes the shut-off valve 64 when the volume of the pressurizing chamber 60 is reduced, thereby boosting the sucked fuel in the pressurizing chamber 60 and feeding it to the high-pressure fuel passage. The pumping amount of the high-pressure fuel pump 50 can be changed according to the valve opening period of the shutoff valve 64 when the volume of the pressurizing chamber 60 is increased. Thus, the ECU 70 has a function of controlling the pumping amount of the high-pressure fuel pump 50 to a desired value by changing the valve opening period of the shutoff valve 64 when the volume of the pressurizing chamber 60 is increased. It has a control means.

  Next, the high-pressure fuel pump control executed by the control device (ECU) for the internal combustion engine according to the present embodiment will be described with reference to FIGS. FIG. 3 is a flowchart of high-pressure fuel pump control executed by the ECU. FIG. 4 is a timing chart showing the operation of the high-pressure fuel pump in the pressure adjustment control. FIG. 5 is a timing chart showing the operation of the high-pressure fuel pump in the intake metering control. In this embodiment, when the pumping amount of the high-pressure fuel pump is lower than a predetermined determination amount, the pumping amount of the high-pressure fuel pump is controlled by suction metering control. It explains together with.

  As shown in FIGS. 2 and 3, in step S <b> 100, the ECU 70 calculates the current engine rotation speed and the pumping amount required for the high-pressure fuel pump 50 from various control signals. The pumping amount of the high pressure fuel pump 50 is calculated from the fuel injection amount injected by the high pressure fuel injection device 40.

  In step S102, the ECU 70 determines whether or not the engine rotation speed exceeds a predetermined determination rotation speed. When the internal combustion engine 10 is operated at an engine speed higher than this, the determination rotational speed is set so that the high-pressure pump-induced pulsation generated in the low-pressure fuel passage has a frequency that is high enough to be absorbed by the dampers 36 and 38. ing. In this embodiment, the determined rotational speed is set to the engine rotational speed when the internal combustion engine 10 is idling. The determination rotation speed is obtained in advance by a matching experiment or the like, and is stored in a ROM (not shown) of the ECU 70.

  If it is determined in step S102 that the engine rotation speed exceeds the predetermined determination rotation speed (Yes), the ECU 70 can absorb the high frequency due to the high pressure pump even if the high pressure pump-induced pulsation occurs in the low pressure fuel passage. In addition, even if the amount of fuel flowing back from the high-pressure fuel pump 50 is large, the low-pressure fuel injection device 30 is sufficiently attenuated before propagating to the pressure accumulating chamber 33 of the low-pressure fuel rail 32 due to the high frequency. It is determined that the fuel injection amount is not affected, and the process proceeds to step S110.

  In step S110, the ECU 70 performs the pressure adjustment control set in the normal high-pressure fuel pump control. As shown in FIG. 4, when the lift amount is decreased from the time point A at which the lift amount of the plunger 54 reaches the maximum value to the time point B at which the lift amount becomes zero, the ECU 70 sets the energization amount flowing through the electromagnetic coil 66 to zero. By setting, the shut-off valve 64 is opened. At this time, the volume of the pressurizing chamber 60 is increasing, and the high-pressure fuel pump 50 sucks fuel into the pressurizing chamber 60 from the low-pressure fuel passage (intake stroke).

  Then, in the first half of the lift amount increase from the time point B at which the lift amount is zero to the time point C during the increase of the lift amount toward the maximum value, the ECU 70 maintains the shutoff valve 64 in the open state as it is. . At this time, the volume of the pressurizing chamber 60 is decreasing, and the high-pressure fuel pump 50 causes the fuel to flow backward from the pressurizing chamber 60 to the low-pressure fuel passage (reverse fashion). As a result of the reverse flow, excess fuel that does not need to be pumped into the high pressure fuel passage out of the fuel sucked into the pressurizing chamber 60 from the low pressure fuel passage is returned to the low pressure fuel passage again.

  Then, in the latter half of the increase in the lift amount from the time point C to the time point D at which the lift amount of the plunger 54 reaches the maximum value, the ECU 70 sets the energization amount of the electromagnetic coil 66 to a predetermined valve closing current value to cut off. The valve 64 is closed. At this time, as the lift amount of the plunger 54 increases, the fuel in the pressurizing chamber 60 is boosted to a pressure higher than the valve opening pressure of the check valve 51, and the high-pressure fuel pump 50 pumps the fuel into the high-pressure fuel passage (pressurization and pressure increase). Pumping stroke). The ECU 70 changes the valve closing period (time point C to time point D) of the shutoff valve 64 when the lift amount of the plunger 54 is increased, thereby setting the pumping amount that the high pressure fuel pump 50 pumps to the high pressure fuel passage to a desired value. It is adjusting.

  On the other hand, if it is determined in step S102 that the engine rotation speed does not exceed the predetermined determination rotation speed (No), the ECU 70 has a low frequency at which the high-pressure pump-induced pulsation cannot be absorbed by the dampers 36 and 38, Depending on the amount of fuel flowing backward from the high-pressure fuel pump 50, it is determined that there is a risk of affecting the fuel injection amount of the low-pressure fuel injection device 30, and the process proceeds to step S104.

  In step S104, the ECU 70 determines whether or not the pumping amount of the high-pressure fuel pump 50 exceeds a predetermined determination amount. This determination amount is set to such a value that a pulsation caused by the high-pressure pump that affects the fuel injection amount of the low-pressure fuel injection device 30 occurs in the low-pressure fuel passage when an amount of fuel exceeding this value flows backward. This determination amount is obtained in advance by a matching experiment or the like, and is stored in the ROM of the ECU 70.

  When it is determined in step S104 that the pumping amount of the high-pressure fuel pump 50 does not exceed the predetermined determination amount (No), the ECU 70 does not prevent the fuel injection amount of the low-pressure fuel injection device 30 even if a back flow occurs in the low-pressure fuel passage. It is determined that no pulsation caused by the high-pressure pump that affects the flow rate is generated, and the process proceeds to step S110.

  On the other hand, when it is determined in step S104 that the pumping amount of the high-pressure fuel pump 50 exceeds a predetermined determination value (Yes), the ECU 70 affects the fuel injection amount of the low-pressure fuel injection device 30 due to the backflow of fuel. It is determined that pulsation caused by the high pressure pump is generated in the low pressure fuel passage, and the process proceeds to step S106.

  In step S106, the ECU 70 performs “inhalation metering control”. As shown in FIG. 5, when the lift amount increases from the time point E when the lift amount of the plunger 54 becomes zero to the maximum time point G, the ECU 70 closes the energization amount of the electromagnetic coil 66 to a predetermined value. By setting the valve current value, the shutoff valve 64 is closed. At this time, the volume of the pressurizing chamber 60 is decreasing, and the high pressure fuel pump 50 pressurizes the fuel in the pressurizing chamber 60. In the middle of increasing the lift amount, the fuel in the pressurizing chamber 60 is increased to a pressure higher than the valve opening pressure of the check valve 51, and fuel starts to be discharged from the check valve 51 into the high pressure fuel passage. From the opening of the check valve 51 to the time point G at which the lift amount of the plunger 54 reaches the maximum value, the high-pressure fuel pump 50 pumps a predetermined pressure-feed amount of fuel into the high-pressure fuel passage (pressure increase / pressure feed stroke).

  Then, at the time point G when the lift amount reaches the maximum value, the ECU 70 increases the energization amount of the electromagnetic coil 66 from the above-described valve closing current value, and sets it to a predetermined valve closing maintaining current value. The ECU sets the energization amount of the electromagnetic coil 66 to the valve closing maintaining current value in the first half of the decrease in the lift amount from the time point G to the time point H during the lift amount decreasing toward zero. 64 valve closing states are maintained. At this time, the volume of the pressurizing chamber 60 is decreasing, and the inside of the pressurizing chamber 60 is depressurized (decompression stroke).

  The valve closing maintaining current value is determined by the force that the energized electromagnetic coil 66 drives the valve body 64a in the valve closing direction, and the valve body 64a is driven by the biasing force of the spring 67 and the flow of fuel flowing into the pressurizing chamber 60. It is set to exceed the sum of the forces drawn in the valve opening direction. The valve closing maintaining current value is obtained in advance by a matching experiment or the like and stored in the ROM of the ECU 70.

  At time H, the ECU 70 opens the shut-off valve 64 by setting the energization amount of the electromagnetic coil 66 to zero. In the latter half of the decrease in the lift amount from the time point H to the time point I at which the lift amount of the plunger 54 becomes zero, the ECU 70 sets the energization amount of the electromagnetic coil 66 to zero and opens the shut-off valve 64. At this time, the pressure chamber 60 is sufficiently decompressed, and the high-pressure fuel pump 50 sucks fuel into the pressure chamber 60 from the low-pressure fuel passage (intake stroke).

  In this manner, the ECU 70 controls the valve opening period (time point H to time point I) of the shutoff valve 64 when the lift amount of the plunger 54 is reduced, so that the fuel sucked into the pressurizing chamber 60 from the low pressure fuel passage in the suction stroke. The amount, that is, the pumping amount pumped from the pressurizing chamber 60 to the high pressure fuel passage in the pressurizing / pressurizing stroke is adjusted to a desired value. Specifically, the ECU 70 sets the end of the opening period of the shut-off valve 64 to a time point I at which the volume of the pressurizing chamber 60 becomes maximum, and the shut-off valve 64 is changed by changing the start time, that is, the valve opening timing. The valve opening time length is adjusted.

  In this way, by changing the start time (valve opening time) and changing the valve opening time length, the ECU 70 continues from the time when the volume of the pressurizing chamber 60 is increased to the pressure reducing stroke when the volume is decreased. 66 can be energized to close the shut-off valve 64. As a result, the high-pressure fuel pump 50 according to the present embodiment does not need to perform the closing operation of the shutoff valve 64 during the decompression of the pressurizing chamber 60. In this way, the ECU 70 performs control so that the pumping amount of the high-pressure fuel pump 50 becomes a desired value in the boosting and pumping stroke of the intake metering control. After performing the control in step S106 described above, the ECU 70 returns to step S100.

  As described above, in this embodiment, when the pumping amount of the high-pressure fuel pump 50 is lower than the predetermined determination amount, the suction control for changing the valve opening period of the shutoff valve 64 when the volume of the pressurizing chamber 60 is increased. The pumping amount of the high-pressure fuel pump 50 is controlled by the amount control means. If the high-pressure fuel pump 50 has a small pumping amount and pressure-feeding control is performed, even if a large amount of fuel flows backward in the low-pressure fuel passage when the volume of the pressurizing chamber 60 is reduced, the suction metering control is performed. When the volume of the pressurizing chamber 60 is decreased, the shutoff valve 64 is always closed to prevent a back flow from occurring in the low pressure fuel passage, thereby suppressing the occurrence of pulsation caused by the high pressure pump in the low pressure fuel passage. In addition, since the intake metering control is performed only when the pumping amount of the high-pressure fuel pump 50 is smaller than the determination amount, the amount of fuel sucked into the pressurizing chamber 60 from the low-pressure fuel passage is small in the suction stroke, and the shut-off valve The force by which the 64 valve bodies 64a are sucked in the valve opening direction is also small, and at this time, the shut-off valve 64 can be reliably closed.

  In the present embodiment, the volume of the pressurizing chamber 60 changes at a frequency proportional to the engine rotation speed. If it is determined that the engine rotation speed exceeds the determination rotation speed, the high-pressure fuel pump 50 Regardless of the pumping amount, the pumping amount of the high-pressure fuel pump is controlled by controlling the pumping amount. Even if pulsation caused by the high-pressure pump occurs in the low-pressure fuel passage by performing the pressure adjustment control, the pulsation has a high frequency and can be attenuated by the dampers 36, 38 and the like. Further, it can be sufficiently attenuated before propagating from the high-pressure fuel pump 50 to the low-pressure fuel injection device 30. By using as much as possible the pressure-feeding metering control that can open and close the shut-off valve 64 more easily than the suction metering control, the high-pressure pump-induced pulsation that affects the fuel injection amount of the low-pressure fuel injection device 30 is suppressed. Can do.

  In this embodiment, the shutoff valve 64 is opened when the valve body 64 a is urged by the urging force of the spring 67, and the valve body 64 a is driven by the electromagnetic force generated by energization of the electromagnetic coil 66 to close the valve. In the case where the pumping amount of the high-pressure fuel pump 50 is controlled by the intake metering control means, the energization amount of the electromagnetic coil 66 when the volume of the pressurizing chamber 60 is increased, and the electromagnetic current when the volume of the pressurizing chamber 60 is decreased. The energization amount of the coil 66 is set to be large. As a result, when the pumping amount of the high-pressure fuel pump 50 is controlled by the intake metering control, the pressure is cut off when the pressure increasing / pressing stroke when the volume of the pressurizing chamber 60 is reduced to the pressure reducing stroke when the volume is increased. The open state of the valve 64 can be maintained satisfactorily. In other words, the energization amount of the electromagnetic coil 66 in the pressurization stroke and the pressure increase / pressure feed stroke when the volume of the pressurization chamber 60 is increased can be made smaller than the pressure reduction stroke when the volume is decreased. The power consumption in the electromagnetic coil 66 can be made as small as possible.

  In this embodiment, when the pumping amount of the high-pressure fuel pump 50 is controlled by the intake metering control, the valve opening period of the shutoff valve 64, that is, the end point is the time point I at which the volume of the pressurizing chamber 60 becomes maximum. Since the initial stage is set to change according to the pumping amount of the high-pressure fuel pump 50, the pressure chamber 60 is continuously increased from when the volume is increased to when the volume is decreased. The shutoff valve 64 can be closed by energizing the electromagnetic coil 66. Thereby, in the intake metering control according to the present embodiment, it is not necessary to perform the closing operation of the shutoff valve 64 during the decompression of the pressurizing chamber 60, and the opening and closing operation of the shutoff valve 64 is made easier. be able to.

  In the present embodiment, the high-pressure fuel pump 50 is driven by the pump cam 56 that is rotated by receiving mechanical power from the crankshaft of the internal combustion engine 10 and the cylinder cam 12 is driven by the pump cam 56. It is assumed that the reciprocating plunger 54 is provided, and the pressurizing chamber 60 is formed by being partitioned by the cylinder hole 12 and the plunger 54, and the volume of the pressurizing chamber 60 is determined by the rotation of the pump cam 56. It was assumed that it changed according to the increase / decrease of the lift amount of 54. In the case of such a high-pressure fuel pump, the pressurized chamber volume of the high-pressure fuel pump is changed regardless of the amount of fuel consumed from the high-pressure fuel passage by the injection of the high-pressure fuel injection device. When the pumping amount of the high-pressure fuel pump is controlled, the backflow of fuel to the low-pressure fuel passage is likely to occur, and pulsation due to the low-frequency high-pressure pump that affects the fuel injection amount of the low-pressure fuel injection device is likely to occur. Therefore, in the case of an internal combustion engine provided with such a high-pressure fuel pump, the control method of the internal combustion engine according to the present embodiment is particularly useful.

  The high-pressure fuel pump to which the present invention can be applied is not limited to the above-described aspect. It has a shut-off valve that can switch between communication and shut-off of the low-pressure fuel passage and the pressurization chamber by opening and closing the valve body. By increasing the volume of the pressurization chamber, fuel is sucked into the pressurization chamber from the low-pressure fuel passage. The present invention can be applied to any high-pressure fuel pump that can pressurize the fuel by reducing the volume of the pressurizing chamber and pump the fuel into the high-pressure fuel passage. For example, the present invention is also applied to an internal combustion engine having a high-pressure fuel pump in which the volume of the pressurizing chamber changes periodically by driving the pump cam with mechanical power from an electric motor. Can do.

  As described above, the control apparatus for an internal combustion engine according to this embodiment includes a low pressure fuel injection device that injects fuel into the intake passage, a high pressure fuel injection device that directly injects fuel into the cylinder, and a fuel that is supplied to the low pressure fuel injection device. This is useful for an internal combustion engine comprising a high-pressure fuel pump that sucks fuel from a low-pressure fuel passage that supplies fuel and pressurizes the fuel into a high-pressure fuel passage that supplies fuel to a high-pressure fuel injection device. Useful for internal combustion engines equipped with a high-pressure fuel pump having a pressurizing chamber whose volume changes periodically according to the operating state, and a shut-off valve that can switch between communication and shut-off of the low-pressure fuel passage and the pressurizing chamber by opening and closing operations It is.

It is sectional drawing which shows schematic structure of the cylinder periphery of the internal combustion engine which concerns on a present Example. 1 is a schematic diagram showing a schematic configuration of an engine system including an internal combustion engine according to an embodiment. It is a flowchart of the high pressure fuel pump control which the control apparatus (ECU) of the internal combustion engine which concerns on a present Example performs. It is a timing chart which shows operation | movement of the high pressure fuel pump in the pressure adjustment control which the control apparatus (ECU) of the internal combustion engine which concerns on a present Example performs. It is a timing chart which shows the operation | movement of the high pressure fuel pump in the intake metering control which the control apparatus (ECU) of the internal combustion engine which concerns on a present Example performs. It is a figure which shows an example of the fuel pressure pulsation in a low-pressure fuel path when the fuel injection-induced pulsation and the high-pressure pump-induced pulsation occur simultaneously.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine system 10 Internal combustion engine 30 Low pressure fuel injection apparatus 32 Low pressure fuel rail 33 Accumulation chamber 34 Low pressure fuel piping 36, 38 Pulsation damper (damper)
DESCRIPTION OF SYMBOLS 40 High pressure fuel injection apparatus 44 High pressure fuel rail 45 Accumulation chamber 46 High pressure fuel piping 50 High pressure fuel pump 51 Check valve 54 Plunger 56 Pump cam 60 Pressurization chamber 62 Suction port 64 Shutoff valve 64a Valve body 66 Electromagnetic coil 67 Spring 69 Exhaust Outlet 70 Internal combustion engine control unit (ECU)
72 Crank angle sensor 80 Fuel tank 82 Low pressure fuel pump 84 Fuel filter 86 Pressure regulating valve 90 Body fuel piping

Claims (5)

A low-pressure fuel injection device that receives fuel from the low-pressure fuel passage and injects fuel into the intake passage;
A high pressure fuel injection device that receives fuel from the high pressure fuel passage and injects fuel into the cylinder;
A pressurizing chamber whose volume changes periodically, and a shutoff valve that can switch between communication and shutoff of the low pressure fuel passage and the pressurizing chamber by opening and closing operation of the valve body, and the low pressure fuel passage by increasing the volume of the pressurizing chamber A high-pressure fuel pump capable of sucking fuel into the pressurizing chamber, boosting the sucked fuel by reducing the volume of the pressurizing chamber, and pumping the fuel into the high-pressure fuel passage;
An internal combustion engine control device comprising:
A pressure adjustment amount control means for controlling the pressure supply amount of the high-pressure fuel pump by changing the valve closing period of the shut-off valve when the volume of the pressurization chamber is reduced;
A suction metering control means for controlling the pumping amount of the high-pressure fuel pump by changing the opening period of the shut-off valve when the volume of the pressurizing chamber is increased;
Have
A control apparatus for an internal combustion engine, characterized in that, when the pumping amount of the high-pressure fuel pump is below a predetermined determination amount, the pumping amount of the high-pressure fuel pump is controlled by the intake metering control means. A control device for an internal combustion engine according to claim 1,
The pressurizing chamber changes its volume at a frequency proportional to the engine speed,
A control device for an internal combustion engine, wherein when the engine rotational speed exceeds a predetermined determination rotational speed, the pumping amount of the high-pressure fuel pump is controlled by the pumping adjustment amount control means regardless of the pumping amount of the high-pressure fuel pump. . The control device for an internal combustion engine according to claim 1 or 2,
The shut-off valve is a valve body that is energized by the energizing force of a spring to open, and the valve element is driven and closed by electromagnetic force generated by energization of an electromagnetic coil.
When the pumping amount of the high-pressure fuel pump is controlled by the suction metering control means, the energizing amount of the electromagnetic coil when the volume of the pressurizing chamber is increased is larger than the energizing amount of the electromagnetic coil when the volume of the pressurizing chamber is decreasing. A control device for an internal combustion engine, characterized by being set large. The control device for an internal combustion engine according to any one of claims 1 to 3,
When the pumping amount of the high-pressure fuel pump is controlled by the suction metering control means, the opening period of the shut-off valve is set at the end when the volume of the pressurizing chamber is maximized, and the start is at the high-pressure fuel pump A control device for an internal combustion engine, wherein the control device is set so as to change according to the pumping amount of the engine. A control device for an internal combustion engine according to any one of claims 1 to 4,
The high-pressure fuel pump includes a pump cam that is rotationally driven by receiving mechanical power from a crankshaft of an internal combustion engine, and a plunger that is driven by the pump cam and reciprocates in a cylinder hole.
The pressurizing chamber is formed by being divided by a cylinder hole and a plunger,
The volume of the pressurizing chamber changes according to the increase or decrease of the lift amount of the plunger due to the rotation of the pump cam.
A control device for an internal combustion engine.

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