JP2008128015A - Fuel supply control device of internal-combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply control device for an internal-combustion engine capable of controlling the fuel pressure accurately irrespective of the cam phase even in case a cam phase variable mechanism is installed, and of maintaining well the fuel consumption and the exhaust gas characteristics. <P>SOLUTION: The fuel supply control device of the internal-combustion engine 3 having the cam phase variable mechanism 50 to change the cam phase CAEX of a cam shaft 9 with respect to a crank shaft 3f, is equipped with a delivery pipe 12 to supply the fuel to a fuel injection valve 10, a pump driving cam 17 installed on the cam shaft, a fuel pump 16 driven by the cam 17 and pressurizing the fuel sucked in from a fuel tank 14 and discharging it to the delivery pipe 12, a spill control valve 26 to operate during the fuel pressurization and circulating the fuel back to the fuel tank 14 for controlling the pressure PF of the fuel in the delivery pipe 12, and an operating timing setting means 2 to set the operating timing THEHPSST of the spill control valve 26 in accordance with the cam phase sensed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel supply control device for an internal combustion engine that controls the supply of fuel to the internal combustion engine, and in particular, a fuel for an internal combustion engine configured to drive a fuel pump that pressurizes the fuel by a pump drive cam of a camshaft. The present invention relates to a supply control device.

  As a conventional fuel supply control device for this type of internal combustion engine, for example, the one disclosed in Patent Document 1 is known. In this fuel supply control device, the fuel stored in the fuel tank is pressurized by the low-pressure pump and then supplied to the pressurizing chamber of the high-pressure pump via the low-pressure side check valve provided at the suction port. The high-pressure pump is provided integrally with a piston provided in the pressurizing chamber, a camshaft that rotates in synchronization with the crankshaft of the internal combustion engine, and a pump drive cam that engages the piston, and the piston on the pump drive cam side. It has a spring that biases it.

  With this configuration, the piston of the high-pressure pump reciprocates in the pressurizing chamber by being driven by the pump drive cam as the camshaft rotates, and when it descends, fuel from the low-pressure pump side enters the pressurizing chamber. While inhaling, pressurize the inhaled fuel when rising. A check valve on the high-pressure side is provided at the discharge port of the pressurizing chamber, and when the pressure of the pressurized fuel reaches a predetermined pressure, the check valve opens so that the fuel is discharged from the discharge port. It is discharged and supplied to the delivery pipe. The supplied fuel is maintained at a predetermined pressure in the delivery pipe, and is injected into each cylinder from a fuel injection valve connected thereto.

  Further, in the pressurizing chamber of the high-pressure pump, a communication port communicating with the fuel tank is formed separately from the suction port, and an electromagnetic valve for opening and closing the communication port is provided. This electromagnetic valve is closed at a predetermined valve closing crank angle before the piston starts to rise under the control of the ECU, and in this state, fuel is pressurized and discharged. Thereafter, the solenoid valve opens at a valve opening crank angle set according to the required fuel discharge amount while the piston is rising. As a result, the discharge operation is completed, and the discharge amount is controlled by releasing (spilling) the fuel in the pressurized chamber to the fuel tank side through the communication port, and the fuel pressure in the delivery pipe is controlled to a predetermined value. Is done.

  However, when such an internal combustion engine is used with a cam phase variable mechanism that controls the valve timing of the engine valve by changing the phase of the camshaft with respect to the crankshaft, there are the following problems. That is, when the camshaft phase with respect to the crankshaft is changed by the cam phase variable mechanism, the timing of the reciprocating motion of the piston of the high-pressure pump driven by the pump drive cam provided on the camshaft is changed. It changes by the same angle as the phase. On the other hand, as described above, in this conventional fuel supply control device, the closing timing and opening timing of the electromagnetic valve are set with reference to the crank angle, so that the timing of the reciprocating motion of the piston is set. It will shift. As a result, the spill control by opening and closing the solenoid valve cannot be performed at an appropriate timing, and the fuel pressure in the delivery pipe deviates from a desired value. This will adversely affect the exhaust gas characteristics.

  The present invention has been made to solve such a problem, and an internal combustion engine has a fuel pump driven by a cam provided on a camshaft, and a cam phase variable mechanism is provided on the camshaft. Even in this case, an object of the present invention is to provide a fuel supply control device for an internal combustion engine that can accurately control the pressure of the injected fuel regardless of the cam phase, thereby maintaining good fuel consumption and exhaust gas characteristics. To do.

JP 2005-307747 A

  In order to achieve this object, the present invention provides a cam phase that is a phase of a camshaft (exhaust camshaft 9) that drives an engine valve (exhaust valve 7 in the embodiment (hereinafter the same in this section)) with respect to the crankshaft 3f. A fuel supply control device for an internal combustion engine that controls supply of fuel to the internal combustion engine 3 having a cam phase variable mechanism 50 that changes (exhaust cam phase CAEX), the fuel tank 14 storing fuel, the internal combustion engine 3 A fuel injection valve 10 for supplying fuel to the combustion chamber 3d, a delivery pipe 12 for supplying pressurized fuel to the fuel injection valve 10, a pump drive cam 17 provided on the camshaft, and a pump drive cam 17 A fuel pump (high pressure pump) that is driven and sucks fuel from the fuel tank 14 side, pressurizes the sucked fuel, and discharges the fuel to the delivery pipe 12 side. 16), the fuel pressure (fuel pressure PF) in the delivery pipe 12 is adjusted by operating at a predetermined operation timing during the pressurization of the fuel by the fuel pump and returning the fuel from the fuel pump to the fuel tank 14 side. The spill control valve 26 to be controlled, the cam phase detection means (crank angle sensor 42, cam angle sensor 45, ECU 2) for detecting the cam phase, and the operation timing (energization) of the spill control valve 26 according to the detected cam phase. And an operation timing setting means (ECU2, 76 to 82 in FIG. 12) for setting the crank angle THEHPSST).

  In this internal combustion engine, the cam phase of the camshaft that drives the engine valve with respect to the crankshaft is changed by the cam phase variable mechanism. Further, in this fuel supply control device, the fuel pump is driven by a pump drive cam provided on the camshaft, sucks fuel from the fuel tank side, pressurizes the sucked fuel, and discharges it to the delivery pipe side. The fuel in the delivery pipe is supplied to the fuel injection valve, and is supplied to the combustion chamber by opening the valve.

  The spill control valve operates at a predetermined timing during the pressurization of the fuel by the fuel pump, and thereby causes the fuel to recirculate from the fuel pump to the fuel tank side, so that the pressure of the fuel in the delivery pipe, that is, the fuel injection pressure Is controlled. Further, the cam phase of the camshaft is detected by the cam phase detecting means, and the operation timing of the spill control valve is set according to the detected cam phase.

  When the cam phase is changed, the operation timing of the fuel pump driven by the pump drive cam provided on the camshaft is changed accordingly. On the other hand, in the present invention, as described above, the operation timing of the spill control valve is set according to the detected actual cam phase. Therefore, even if the cam phase is changed, the operation timing of the spill control valve is not changed. There is no deviation from the operation timing of the fuel pump, and the relationship between the two can be maintained. As a result, the spill control can be performed at an appropriate timing regardless of the cam phase, and the fuel pressure in the delivery pipe can be accurately controlled to a desired value, so that fuel consumption and exhaust gas characteristics can be maintained well. .

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration of an internal combustion engine 3 and its fuel supply control device 1 to which the present invention is applied. The fuel supply control device 1 includes an ECU 2 (see FIG. 2), and executes various control processes including fuel supply control to an internal combustion engine (hereinafter referred to as “engine”) 3.

  The engine 3 is a DOHC type in-line four-cylinder gasoline engine having four cylinders 3a (only one is shown), and is mounted on a vehicle (not shown). A combustion chamber 3d is formed between the piston 3b and the cylinder head 3c of each cylinder 3a. A recess 3e is formed at the center of the upper surface of the piston 3b. In addition, an intake pipe 4 and an exhaust pipe 5 are connected to the cylinder head 3c, and a pair of intake valves 6 and 6 and exhaust valves 7 and 7 (both of them face the intake port 4a and the exhaust port 5a, respectively) 1 is shown), and an intake camshaft 8 and an exhaust camshaft 9 for driving the intake valve 6 and the exhaust valve 7 respectively are attached.

  A fuel injection valve (hereinafter referred to as “injector”) 10 is attached to the center of the top wall of the cylinder head 3c so as to face the combustion chamber 3d. That is, the engine 3 is of a so-called direct injection type in which fuel is directly injected from the injector 10 into the combustion chamber 3d. Further, a spark plug 11 is attached to the cylinder head 3 c at a position adjacent to the injector 10. The discharge state of the spark plug 11 is controlled by the ECU 2 so that the air-fuel mixture in the combustion chamber 3d is combusted at a timing according to the ignition timing.

  Each injector 10 is connected to a fuel tank 14 via a respective fuel supply short pipe 10 a, delivery pipe 12 and fuel supply pipe 13. A low pressure pump 15 is provided at the most upstream position of the fuel supply pipe 13, and a high pressure pump 16 is provided in the middle of the fuel supply pipe 13.

  The low-pressure pump 15 is an electric pump, and sucks fuel in the fuel tank 14 under the control of the ECU 2 and pressurizes the sucked fuel at a predetermined low pressure (for example, 0.35 MPa), and then supplies fuel. It discharges to the high-pressure pump 16 side through the low-pressure pipe part 13a of the pipe 13. The high-pressure pump 16 is driven by a pump drive cam 17 (see FIG. 3) provided integrally with the exhaust camshaft 9, and sucks the fuel discharged from the low-pressure pump 15 and further increases the sucked fuel (for example, After pressurizing at a maximum of 12 MPa, it is discharged to the delivery pipe 12 side through the high pressure pipe portion 13 b of the fuel supply pipe 13.

  The high-pressure fuel stored in the delivery pipe 12 is sent to the injector 10 via the fuel supply short pipe 10a, and is directly injected into the combustion chamber 3d by opening the injector 10. The fuel pressure (hereinafter referred to as “fuel pressure”) PF in the delivery pipe 12 is controlled by the ECU 2 as described later. A fuel pressure sensor 41 for detecting the fuel pressure PF is attached to the delivery pipe 12, and a detection signal is output to the ECU 2. Further, the valve opening time and valve opening timing of the injector 10, that is, the fuel injection amount and the fuel injection timing are also controlled by the ECU 2.

  Next, the configuration of the high-pressure pump 16 will be described with reference to FIG. As shown in the figure, the high-pressure pump 16 is of a piston type, is slidably disposed in the pressurizing chamber 18, and includes a plunger 19 that engages with a pump drive cam 17 of the exhaust camshaft 9, and a plunger A spring 20 is provided to bias 19 to the pump drive cam 17 side. Since this configuration and the pump drive cam 17 have two cam crests that are equally spaced in the circumferential direction, the plunger 19 moves through the pressurizing chamber 18 at an equal cycle every time the exhaust camshaft 9 makes one revolution. Make a round trip.

  The high pressure pump 16 has a suction port 21 and a discharge port 22 communicating with the pressurizing chamber 18. The suction port 21 is connected to the low pressure pump 15 via the low pressure pipe portion 13 a of the fuel supply pipe 13. The discharge port 22 is connected to the delivery pipe 12 via the high-pressure pipe portion 13b.

  A check valve 23 is provided between the pressurizing chamber 18 and the discharge port 22. The check valve 23 includes a valve body 24 and a spring 25 that biases the valve body 24 toward the pressurizing chamber 18. The fuel pressure in the pressurizing chamber 18 is higher than the fuel pressure PF of the delivery pipe 12. When it becomes larger, the valve is opened to allow fuel to be discharged from the discharge port 22, while in other cases, the valve is closed to prevent the fuel from flowing backward.

  A spill control valve 26 is provided between the pressurizing chamber 18 and the suction port 21. The spill control valve 26 is composed of a solenoid valve, and is driven by a solenoid 27, a plunger 28 that is driven by the solenoid 27 and has a valve element 29 at the tip, and a spring 30 that biases the plunger 28 toward the pressurizing chamber 18 side. Etc. The spill control valve 26 is of a normally open type, and when the solenoid 27 is not energized, the valve 27 is maintained open by the urging force of the spring 30 and opens the suction port 21, while the solenoid 27 is energized by energization. When the valve is closed, the suction port 21 is closed.

  In the high-pressure pump 16 having the above configuration, the spill control valve 26 is maintained in the open state while the plunger 19 is being lowered (retracted from the pressurizing chamber 18) by the pump drive cam 17, whereby the fuel is supplied to the low-pressure pump 15. The air is sucked into the pressurizing chamber 18 from the side through the low pressure pipe portion 13a and the suction port 21. On the other hand, when the plunger 19 is raised, the spill control valve 26 is closed by energization, so that the fuel pressure in the pressurizing chamber 18 rises. When the fuel pressure in the pressurizing chamber 18 exceeds the fuel pressure PF of the delivery pipe 12, the check valve 24 is opened, so that the fuel in the pressurizing chamber 18 is discharged from the discharge port 22 and the high-pressure pipe section. It is discharged to the delivery pipe 12 side through 13b.

  Further, when the plunger 19 is lifted, when the spill control valve 26 is kept open until the plunger 19 is closed and then closed, the fuel sucked into the pressurizing chamber 18 is closed by the spill control valve 26. Until then, the fuel is returned to the fuel tank 14 through the opened suction port 21 through the low pressure pipe portion 13a and the low pressure pump 15. Hereinafter, the return of the fuel sucked into the high-pressure pump 16 to the low-pressure side is referred to as “spill”. Further, after the spill control valve 26 is closed, the fuel is discharged when the fuel pressure in the pressurizing chamber 18 exceeds the fuel pressure PF of the delivery pipe 12 in accordance with the closing timing.

  Therefore, by controlling the valve closing timing (spill operation end timing) of the spill control valve 26 when the plunger 19 is lifted, the fuel spill amount can be adjusted, whereby the fuel discharge amount to the delivery pipe 12 and The fuel pressure PF of the delivery pipe 12 (the fuel injection pressure of the injector 10) can be controlled.

  Returning to FIG. 1, the intake camshaft 8 for driving the intake valve 6 is rotatably supported by the cylinder head 3c via a holder (not shown). The intake camshaft 8 is connected to the crankshaft 3f via an intake sprocket and a timing chain (both not shown), and rotates once every two rotations of the crankshaft 3f. An intake cam 31 is integrally provided on the intake camshaft 8, and the intake valve 6 is opened and closed by the intake cam 31 as the intake camshaft 8 rotates.

  An exhaust camshaft 9 that drives the exhaust valve 7 is also rotatably supported by the cylinder head 3c via a holder (not shown). The exhaust camshaft 9 is connected to the crankshaft 3f via an exhaust sprocket and a timing chain (both not shown), and rotates once every two rotations of the crankshaft 3f. The exhaust camshaft 9 is integrally provided with an exhaust cam 32 in addition to the pump drive cam 17, and the exhaust valve 7 is driven to open and close by the exhaust cam 32 as the exhaust camshaft 9 rotates. The

  Further, a cam phase variable mechanism 50 is provided between the exhaust camshaft 9 and the exhaust sprocket. Its configuration will be described later.

  The intake pipe 4 is provided with a throttle valve 33. The throttle valve 33 is connected to a TH actuator 34 that combines a motor and a gear mechanism (both not shown), and the opening degree of the throttle valve 33 is controlled by the ECU 2 via the TH actuator 34. The intake air amount sucked into the combustion chamber 3d is controlled.

  A crank angle sensor 42 is provided on the crankshaft 3 f of the engine 3. The crank angle sensor 42 includes a magnet rotor 42a and an MRE pickup 42b, and outputs a CYL signal, a CRK signal, and a TDC signal, which are pulse signals, to the ECU 2 as the crankshaft 3f rotates.

  The CYL signal is used for cylinder discrimination and is output at every crank angle of 720 °. The TDC signal is a signal indicating that the piston 3b of each cylinder 3a is at a predetermined crank angle position slightly ahead of the TDC position of the intake stroke, and in this example of the 4-cylinder type, the crank angle is 180 °. Is output every time. The CRK signal is output every predetermined crank angle (for example, 30 °). The ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal.

  Further, the ECU 2 sets a crank angle stage PSTG used for spill control, which will be described later, based on the above three signals. As shown in FIG. 13, this crank angle stage PSTG divides a crank angle CAATDC having a cycle of 360 ° with reference to the crank angle generated by a TDC signal for a certain cylinder 3a (= 0 °) every 30 °, and sequentially stages. Numbers 0 to 11 are assigned.

  As shown in FIG. 2, the ECU 2 receives a detection signal from the accelerator opening sensor 43 indicating an accelerator opening AP, which is an operation amount of an accelerator pedal (not shown), from the battery sensor 44 to the injector 10 or the like. A detection signal representing a voltage (hereinafter referred to as “battery voltage”) VB of a battery (not shown) as a power source for the spill control valve 26 of the high-pressure pump 16 is output.

  Next, the cam phase varying mechanism 50 will be described. The cam phase varying mechanism 50 changes the relative phase of the exhaust camshaft 9 with respect to the crankshaft 3f (hereinafter referred to as “exhaust cam phase”) CAEX steplessly within a predetermined range. 9 at the end of the exhaust sprocket side. As shown in FIG. 4, the cam phase varying mechanism 50 includes a housing 51, a three-blade vane 52, a hydraulic pump 53, an electromagnetic valve 54, and the like.

  The housing 51 is configured integrally with the exhaust sprocket, and includes three partition walls 51a formed at equal intervals in the circumferential direction. The vane 52 is coaxially attached to the exhaust camshaft 9, extends radially outward, and is rotatably accommodated in the housing 51. In the housing 51, three advance chambers 55 and three retard chambers 56 are formed between the partition wall 51 a and the vane 52.

  The hydraulic pump 53 is a mechanical type coupled to the crankshaft 3f, and sucks lubricating oil stored in the oil pan 3e of the engine 3 through the oil passage 57c as the crankshaft 3f rotates. In a state where the pressure is increased, the pressure is supplied to the electromagnetic valve 54 via the oil passage 57c.

  The electromagnetic valve 54 is a combination of a spool valve mechanism 54a and a solenoid 54b, and is connected to the advance chamber 55 and the retard chamber 56 via the advance oil passage 57a and the retard oil passage 57b, respectively. The oil pressure Poil supplied from the hydraulic pump 53 is output to the advance chamber 55 and the retard chamber 56 as the advance oil pressure Pad and the retard oil pressure Prt, respectively. The solenoid 54b changes the advance hydraulic pressure Pad and the retard hydraulic pressure Prt by moving the spool valve body of the spool valve mechanism 54a within a predetermined movement range by the phase control input U_CAEX from the ECU 2.

  In the cam phase variable mechanism 50 described above, while the hydraulic pump 53 is operating, the electromagnetic valve 54 operates in accordance with the phase control input U_CAEX, so that the advance hydraulic pressure Pad becomes the advance chamber 55 and the retard hydraulic pressure Prt becomes the retard angle. Each is supplied to the chamber 56, whereby the relative phase between the vane 52 and the housing 51 is changed to the advance side or the retard side. As a result, the exhaust cam phase CAEX continuously changes between a predetermined maximum retardation value and a predetermined maximum advance value, so that the valve timing of the exhaust valve 7 is the maximum indicated by a solid line in FIG. It is changed steplessly between the retard angle timing and the most advanced angle timing indicated by a two-dot chain line.

  On the other hand, a cam angle sensor 45 (see FIG. 2) is provided at the end of the exhaust camshaft 9 opposite to the cam phase varying mechanism 50. Like the crank angle sensor 42, the cam angle sensor 45 is composed of a magnet rotor and an MRE pickup (both not shown), and with the rotation of the exhaust camshaft 9, an EXCAM signal, which is a pulse signal, is transmitted in a predetermined manner. It outputs to ECU2 for every cam angle (for example, 1 degree). The ECU 2 calculates the exhaust cam phase CAEX based on the EXCAM signal and the above-described CRK signal.

  The above-described phase control input U_CAEX for controlling the cam phase variable mechanism 50 is the target exhaust cam phase CAEXCMD in which the detected exhaust cam phase CAEX is set based on the engine speed NE, the accelerator pedal opening AP, and the like. Is calculated by a predetermined feedback control algorithm so as to converge.

  In this embodiment, the ECU 2 constitutes a cam phase detection means and an operation timing setting means, and is constituted by a microcomputer including a CPU, a RAM, a ROM, an I / O interface (all not shown), and the like. Yes. The ECU 2 controls the fuel injection time and fuel injection timing of the injector 10 and the ignition timing of the spark plug 11 in accordance with the control program stored in the ROM in accordance with the detection signals of the various sensors 41 to 45 described above. The operation of the high-pressure pump 16 is controlled as follows.

  FIG. 6 shows a main flow of control processing of the high-pressure pump 16. This process is executed in synchronization with the generation of the TDC signal. In this process, first, in step 1 (illustrated as “S1”, the same applies hereinafter), execution determination processing for high pressure control of the high pressure pump 16 is performed. In this process, when the setting of the crank angle based on the TDC signal is not completed, when a failure such as disconnection of the fuel pressure sensor 41 is detected, or when a failure of the high-pressure pump 16 is detected, The high pressure control execution flag F_HPUMPACT is set to “0” on the assumption that the high pressure control execution condition of the high pressure pump 16 is not satisfied.

  In the next step 2, full spill / full discharge request determination processing is executed. This process determines whether there is a request for “full spill” to maximize the spill amount or “full spill” to maximize the spill amount by setting the discharge amount of the high-pressure pump 16 to zero. FIG. 8 shows the subroutine.

  In this process, first, in step 11, a target fuel pressure PFOBJ that is a target of the fuel pressure PF of the delivery pipe 12 is calculated. 9 and 10 show the subroutine. In this process, first, a current value of a target fuel pressure status ST_PFOJ, which will be described later, is shifted to a previous value ST_PFOJZ (step 31).

  Next, it is determined whether or not the high-pressure control execution flag F_HPUMPACT set in step 1 is “1” (step 32). If this answer is NO and the execution condition of the high pressure control of the high pressure pump 16 is not satisfied, the target fuel pressure PFOBJ is set to the fourth predetermined pressure # corresponding to the suction pressure of the high pressure pump 16 (= the discharge pressure of the low pressure pump 15). PFEED (for example, 0.35 Mpa) is set (step 33), and the target fuel pressure status ST_PFOJ representing the set state of the target fuel pressure PFOBJ is set to “3” (step 34).

  If the answer to step 32 is YES, it is determined whether or not a fuel pressure sensor failure flag F_FSHPPS is “1” (step 35). If the answer is YES and the fuel pressure sensor 41 is out of order, the target fuel pressure PFOBJ is set to a first predetermined pressure # PFOBJ0 (for example, 8 Mpa) larger than the fourth predetermined pressure #PFEED (step 36) and the target The fuel pressure status ST_PFOJ is set to “0” (step 37).

  When the answer to step 35 is NO, it is determined whether or not the fuel injection mode INJMODE is “0” (step 38). If the answer is YES and the fuel injection is stopped, the steps 33 and 34 are executed.

  When the answer to step 38 is NO, it is determined whether or not the engine speed NE is equal to or lower than a predetermined first speed # NPFOJ1 (for example, 1000 rpm) (step 39). If the answer is YES and NE≤ # NPFOJ1 is established and the engine is in the low speed range, the steps 36 and 37 are executed, and the target fuel pressure PFOBJ is set to the first predetermined pressure # PFOBJ0.

  When the answer to step 39 is NO, it is determined whether or not the engine speed NE is equal to or lower than a predetermined second speed # NPFOJ2 (for example, 5000 rpm) higher than the first speed # NPFOJ1 (step 40). If the answer is YES, # NPFOJ1 <NE ≦ # NPFOJ2 is established, and the target fuel pressure PFOBJ is set to a second predetermined pressure # PFOBJ1 (for example, 10 Mpa) that is higher than the first predetermined pressure # PFOBJ0 when in the middle rotation range. Along with (Step 41), the target fuel pressure status ST_PFOJ is set to “1” (Step 42).

  On the other hand, if the answer to step 40 is NO and NE> # NPFOJ2 is established and the engine speed is high, the target fuel pressure PFOBJ is set to a third predetermined pressure # PFOBJ2 (for example, 11 Mpa) that is larger than the second predetermined pressure # PFOBJ1. In addition to setting (step 43), the target fuel pressure status ST_PFOJ is set to “2” (step 44).

  As described above, the target fuel pressure PFOBJ is set to the fourth predetermined pressure #PFEED corresponding to the suction pressure when the high pressure control of the high pressure pump 16 is not executed. During the high pressure control, the higher the engine speed NE, The first to third predetermined pressures # PFOBJ0 to # PFOBJ2 are set in three stages. This is because the higher the engine speed NE, the shorter the time allotted for fuel injection of the injector 10 and a higher fuel pressure is required.

  Subsequent to Step 34, 37, 42 or 44, Steps 45 to 49 are used to calculate a fuel pressure feedback coefficient KHPFPID described later for feedback control of the fuel pressure PF based on the target fuel pressure PFOBJ set as described above. Calculate various parameters.

  Specifically, the current fuel pressure deviation DPFOBJ is shifted to the previous value DPFOBJZ (step 45), and the deviation between the fuel pressure PF detected by the fuel pressure sensor 41 and the target fuel pressure PFOBJ is calculated as the fuel pressure deviation DPFOBJ (step 46). . Further, the current value of the primary change amount DDPFOBJ of the fuel pressure deviation DPFOBJ is shifted to the previous value DDPFOBJZ (step 47). Next, the deviation between the fuel pressure deviation DPFOBJ and its previous value DPFOBJZ is calculated as a primary change amount DDPFOBJ (step 48), and the deviation between this primary change amount DDPFOBJ and its previous value DDPFOBJZ is calculated as a secondary change amount DDDPFOBJ. (Step 49), and this process is terminated.

  Returning to FIG. 7, in steps 12 to 14 following step 11, whether or not the high pressure control execution flag F_HPUMPACT is “1”, whether or not the fuel pressure injection pause mode INJMODE is “0”, and It is determined whether or not the fuel cut flag F_FC is “1”.

  As a result of these determinations, when the answer to step 12 is NO and the execution condition of the high-pressure control of the high-pressure pump 16 is not satisfied, the answer to step 13 is YES and when fuel injection is stopped, or step 14 If the answer to the question is YES and fuel cut is to be executed, it is not necessary to discharge fuel from the high-pressure pump 16, so that the full spill is to be executed and the full discharge request flag F_HPSTGFL is set to “0” (step 15). At the same time, the full spill request flag F_HPNFLSP is set to “0” (step 16), and this process is terminated.

  On the other hand, when the answer to step 12 is YES and both the answers to steps 13 and 14 are NO, a process for setting the full spill request flag F_RQPFDN for reducing the target fuel pressure is executed (step 17). In this process, based on the target fuel pressure status ST_PFOJ set in the process of FIG. 9, it is determined whether or not the target fuel pressure PFOBJ has been changed to the decreasing side, and immediately after the change to the decreasing side is determined, A full spill request flag F_RQPFDN for reducing the target fuel pressure is set to “1”, assuming that a full spill should be executed in order to quickly reduce the PF.

  Next, a process for calculating the fuel injection amount TOUTHPMX for high pressure control of the high pressure pump 16 is executed (step 18). In this process, the required fuel amount for each cylinder is calculated based on the actual fuel injection amount and the fuel adhesion amount for each cylinder, and the maximum value among them is the fuel injection amount for high pressure control (hereinafter simply referred to as “fuel injection”). It is calculated as “amount” “TOUTHPMX”.

  Next, it is determined whether or not the fuel pressure sensor failure flag F_FSHPPS is “1” (step 19). If the answer is YES and the fuel pressure sensor 41 is out of order, the full discharge request flag F_HPSTGFL is set to “0”, assuming that normal fuel pressure control is performed without performing full discharge or full spill (step 20). Then, the full spill request flag F_HPNFLSP is set to “1” (step 21), and this process is terminated.

  When the answer to step 19 is NO, it is determined whether or not the full spill request flag F_RQPFDN for reducing the target fuel pressure set in step 17 is “1” (step 22). If the answer is YES and a full spill for reducing the target fuel pressure is required, steps 15 and 16 are executed.

  When the answer to step 22 is NO, it is determined whether or not the moving average value PF_ACT of the fuel pressure PF is higher than a predetermined first threshold value #PFFLL (eg, 0.4 MPa) on the low pressure side (step 23). . If the answer is NO and the delivery pipe 12 is in the low fuel pressure state, it is determined whether or not the full spill request flag F_HPNFLSP is “1” (step 24). If the answer is YES and a full spill is not required, the process proceeds to steps 20 and 21 and normal fuel pressure control is executed.

  When the answer to step 24 is NO, it is determined whether or not the fuel injection amount TOUTHPMX calculated in step 18 is larger than a predetermined maximum discharge amount #TOUTHPON of the high-pressure pump 16 (step 25). When the answer is YES, the required fuel injection amount TOUTHPMX exceeds the discharge capacity of the high-pressure pump 16, so the process proceeds to steps 15 and 16 and full spill is executed. On the other hand, if the answer to step 25 is NO, the process proceeds to the steps 20 and 21, and normal fuel pressure control is executed.

  If the answer to step 23 is YES, it is determined whether or not the moving average value PF_ACT of the fuel pressure PF is higher than a predetermined second threshold value #PFFLH (for example, 5 MPa) on the high pressure side (step 26). When this answer is NO and #PFFLL <PF_ACT ≦ # PFFLH is established and the delivery pipe 12 is in the intermediate fuel pressure state, the full discharge request flag F_HPSTGFL is set to execute full discharge in order to quickly raise the fuel PF. Set to “1” (step 27), and then proceed to step 21 to set the full spill request flag F_HPNFLSP to “1”, and the process is terminated.

  If the answer to step 26 is YES, PF_ACT> #PFFLH is established, and the delivery pipe 12 is in a high fuel pressure state, whether the fuel injection amount TOUTHPMX is larger than the maximum discharge amount #TOUTHPON as in step 25 or not. A determination is made (step 28). When the answer is YES, even if the delivery pipe 12 is in a high fuel pressure state, the process proceeds to steps 27 and 21 to prevent the fuel pressure PF from being lowered due to a large amount of fuel being injected. Execute. On the other hand, when the answer to step 28 is NO, the process proceeds to steps 20 and 21, and normal fuel pressure control is executed.

  Returning to FIG. 6, in step 3 following step 2, calculation processing of the fuel pressure feedback coefficient KHPFPID is executed. In this process, the fuel pressure feedback coefficient KHPFPID is calculated so that the fuel pressure PF becomes the target fuel pressure PFOBJ using the fuel pressure deviation DPFOBJ, the primary change amount DDPFOBJ, the secondary change amount DDDPFOBJ, and the like calculated in step 45 and after in FIG. The

  Next, in step 4, a process for calculating the discharge time THPCAL of the high-pressure pump 16 is executed. FIG. 11 shows the subroutine. The discharge time THPCAL represents the time interval between the energization timing to the spill control valve 26 and the discharge end timing. In this process, first, in step 51, it is determined whether or not the full spill request flag F_HPNFLSP is “1”. If the answer is NO and a full spill is required, the discharge time THPCAL is set to a value of 0 (step 52), and this process is terminated.

  If the answer to step 51 is YES, it is determined whether or not the full discharge request flag F_HPSTGFL is “1” (step 53). If the answer is YES and full discharge is requested, a map value #THPMFL for full discharge is searched from a predetermined map (not shown) according to the engine speed NE, and the basic discharge time THPMX is obtained. Set (step 54).

  When the answer to step 53 is NO, it is determined whether or not the target fuel pressure status ST_PFOJ is “0” (step 55). If the answer is YES and the target fuel pressure PFOBJ is set to the lowest stage during normal fuel pressure control, the low level is determined from a predetermined map (not shown) according to the engine speed NE and the fuel injection amount TOUTHPMX. The first map value # THPM0 for the target fuel pressure is retrieved and set as the basic discharge time THPMX (step 56).

  When the answer to step 55 is NO, it is determined whether or not the target fuel pressure status ST_PFOJ is “1” (step 57). When the answer is YES and the target fuel pressure PFOBJ is set to the middle stage, the second map for the middle target fuel pressure is determined from a predetermined map (not shown) according to the engine speed NE and the fuel injection amount TOUTHPMX. The value # THPM1 is retrieved and set as the basic discharge time THPMX (step 58).

  On the other hand, when the answer to step 57 is NO, that is, when the target fuel pressure status ST_PFOJ is “2” and the target fuel pressure PFOBJ is set to the highest stage, a predetermined map is set according to the engine speed NE and the fuel injection amount TOUTHPMX. The third map value # THPM2 for high target fuel pressure is searched from (not shown) and set as the basic discharge time THPMX (step 59).

  The first to third map values # THPM0 to # THPM2 are set to larger values as the target fuel pressure PFOBJ is higher when the engine speed NE and the fuel injection amount TOUTHPMX are the same. ing. This is because the higher the target fuel pressure PFOBJ is, the larger the amount of fuel to be discharged from the high-pressure pump 16 is.

  Following step 54, 56, 58 or 59, in step 60, a map value #THPVB is searched from a predetermined map (not shown) in accordance with the battery voltage VB detected by the battery sensor 44, and the energization invalid time. Is set as a battery correction term THPVBX corresponding to (step 60).

  Next, the provisional value thptmp of the corrected basic discharge time THPFB is calculated by multiplying the basic discharge time THPMX by the fuel pressure feedback coefficient KHPFPID calculated in step 3 (step 61).

  Next, a map value #THPFBH is retrieved from a predetermined map (not shown) according to the engine speed NE, and set as an upper limit value THPFBHX (step 62). Then, using this upper limit value THPFBHX, a value obtained by performing a limit process on the provisional value thptmp is set as a corrected basic discharge time THPFB (step 63).

  Next, by adding the battery correction term THPVBX obtained in step 60 to the corrected basic discharge time THPFB, the discharge time THPCAL is finally calculated (step 64), and this process ends.

  Returning to FIG. 6, in step 5 following step 4, spill control parameter calculation processing is executed. In this process, parameters necessary for controlling energization of the spill control valve 26 are calculated based on the discharge time THPCAL calculated as described above, and FIG. 12 shows a subroutine thereof.

  In this process, first, in step 71, it is determined whether or not the full spill request flag F_HPNFLSP is “1”. If the answer is NO and full spill is required, the spill control valve 26 is not driven, and the energized crank angle THEHPSST, energized crank angle stage HPSTG, energized waiting time THPOFF, and energized time THPOUT, all of which will be described later, are all values. It is set to 0 (steps 72 to 75), and this process is terminated.

On the other hand, when the answer to step 71 is YES and full spill is not required, the provisional value thehpcalccl of the energized crank angle THEHPPSST is calculated by the following equation (1) using the discharge time THPCAL and the exhaust cam phase CAEX (step) 76).
thehpcalcl
= # THEHPEND- (THPCAL / CRMEN) × 30 deg-CAEX
... (1)

  Here, #THEHPEND is a predetermined reference discharge end crank angle (for example, 308 ° CAATDC) (see FIG. 13). This reference discharge end crank angle #THEHPEND corresponds to the end timing of the fuel discharge operation of the high-pressure pump 16 when the exhaust cam phase CAEX = 0. CRMEN is a time interval between CRK signals calculated from the latest output status of the CRK signal. Therefore, the second term (THPCAL / CRMEN) × 30 deg on the right side is obtained by converting the discharge time THPCAL into a crank angle, and is hereinafter referred to as “discharge time equivalent crank angle CAHPCAL”.

  As is clear from the above, the provisional value thehpcalcl calculated by the equation (1) is advanced from the predetermined reference discharge end crank angle #THEHPEND by the exhaust cam phase CAEX, and further advanced by the discharge time equivalent crank angle CAHPCAL. This corresponds to the crank angle (see FIG. 13).

  Next, limit processing is performed on the calculated provisional value thehpcalcl using a predetermined value #CAATDCLMT (for example, 180 °) as a lower limit value (step 77). Next, the provisional value thehpcalcl is corrected by subtracting the sensor correction amount IGSD from the provisional value thehpcalcl subjected to the limit processing (step 78). This sensor correction amount IGSD is for compensating for the detection delay of the crank angle sensor 42 and the cam angle sensor 45. Next, limit processing with the predetermined value #CAATDCLMT as the lower limit is performed again on the corrected provisional value thehpcalcl (step 79).

  Next, the provisional value thehpcalcl is set as the energized crank angle THEHPSST at which energization of the spill control valve 26 is started (step 80). Further, based on the energized crank angle THEHPSST, an energized crank angle stage HPSTG that is a crank angle stage that actually starts energization, and an energization waiting time THPOFF that is a waiting time from the start of the energized crank angle stage HPSTG is expressed by the following equation: Calculations are made in (2) and (3), respectively (steps 81 and 82).

HPSTG = QSTG / 30deg (2)
THPOFF = (RSTG / 30deg) × CRMEN (3)
Here, QSTG and RSTG are a “quotient” and a “remainder” when the energized crank angle THEHPSSTTHEHPSST is divided by 30 deg which is the crank angle per crank stage. CRMEN is a time interval between CRK signals used in Equation (1).

  Finally, a map value #THPOUTM is retrieved from a predetermined map (not shown) according to the engine speed and the battery voltage VB, and is set as the energization time THPOUT of the spill control valve 26 (step 83), and this process ends. To do.

  FIG. 13 shows an operation example obtained by the processing of FIG. The solid line in FIG. 6A shows the lift of the plunger 19 of the high-pressure pump 16 when the exhaust cam phase CAEX controlled by the cam phase varying mechanism 50 is at the most retarded position and has a value of zero. In this case, since CAEX = 0 in the equation (1), as shown in FIG. 6C, the energized crank angle THEHPPSST (provisional value thehpcalcl) is determined from the predetermined reference discharge end crank angle #THEHPEND. It is set to a crank angle advanced by the discharge time equivalent crank angle CAHPCAL.

  Then, when the energization waiting time THPOFF calculated by the equation (3) has elapsed from the beginning of the energization crank angle stage HPSTG (8 in this example) calculated by the equation (2) based on the energization crank angle THEHPPSST. Then, energization of the spill control valve 26 is started. As a result, the spill control valve 26 that has opened the suction port 21 is closed, the spill operation ends, and the discharge operation starts. This discharge operation ends at the reference discharge end crank angle #THEHPEND.

  On the other hand, when the exhaust cam phase CAEX is advanced from the most retarded position, as indicated by a two-dot chain line in FIG. 10A, the energized crank angle THEHPPSST, as shown in FIG. Is set to a crank angle that is advanced from the reference discharge end crank angle #THEHPEND by the exhaust cam phase CAEX and further advanced by the discharge time equivalent crank angle CAHPCAL by the equation (1), and the energized crank angle stage HPSTG = 7, energization of the spill control valve 26 is started. As described above, the timing of energizing the spill control valve 26 is advanced by the same crank angle as the exhaust cam phase CAEX, and accordingly, the timing of the end of the spill operation and the start and end of the discharge operation are also determined by the exhaust cam phase CAEX. Shift to the advance side by the amount of.

  As described above, according to the present embodiment, the energized crank angle THEHPPSST of the spill control valve 26 during pressurization of the high-pressure pump 16 is shifted to the advance side by the detected actual exhaust cam phase CAEX. To set. Therefore, even if the exhaust cam phase CAEX is changed, the end timing of the spill operation by closing the spill control valve 26 does not deviate from the lift timing of the plunger 19 of the high-pressure pump 16, and the relationship between the two is maintained. can do. As a result, regardless of the exhaust cam phase CAEX, the end of the spill operation, the start and end timing of the discharge operation can be appropriately controlled, and the fuel pressure PF in the delivery pipe 12 can be accurately controlled to the target fuel pressure PFOBJ. The exhaust gas characteristics can be maintained well.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, the spill control valve 26 of the embodiment is a normally open type, and performs a spill operation by closing the suction port at a predetermined timing during pressurization of the high-pressure pump 16. The present invention is not limited to this, and as shown in the prior art, during the pressurization of fuel, a communication port that communicates with the fuel tank side and that is separate from the suction port is sequentially closed and opened by a spill control valve. By doing so, a spill operation may be performed. In that case, a similar effect can be obtained by setting both the closing timing and opening timing of the spill control valve in accordance with the cam phase.

  In the embodiment, basically, the energized crank angle THEHPSST of the spill control valve 26 is set to the same angle and advance side as the detected exhaust cam phase CAEX, but depending on the operating state of the engine 3 and the like. Thus, an appropriate correction may be added. Furthermore, although the embodiment is an example in which the pump drive cam 17 and the cam phase variable mechanism 50 are provided on the exhaust camshaft 9 side, these may of course be provided on the intake camshaft 8 side. . In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

1 is a diagram schematically showing a fuel supply control device according to an embodiment of the present invention together with an internal combustion engine. It is a block diagram which shows schematic structure of ECU2 of a fuel supply control apparatus. It is sectional drawing which shows the structure of a high pressure pump. It is a schematic diagram which shows schematic structure of a cam phase variable mechanism. It is a figure which shows the valve lift curve of the exhaust valve obtained by a cam phase variable mechanism. It is a flowchart which shows the main flow of the control processing of a high pressure pump. It is a flowchart which shows the subroutine of the request | requirement determination process of the full spill and full discharge of FIG. It is a flowchart which shows the continuation part of FIG. It is a flowchart which shows the subroutine of the calculation process of the target fuel pressure of FIG. 10 is a flowchart showing a continuation of FIG. 9. It is a flowchart which shows the subroutine of the calculation process of the discharge time of FIG. FIG. 7 is a flowchart showing a subroutine of spill control parameter calculation processing of FIG. 6. FIG. It is a figure which shows the operation example obtained by the process of FIG.

Explanation of symbols

1 Fuel supply control device 2 ECU (cam phase detection means, operation timing setting means)
3 Internal combustion engine 3d Combustion chamber 3f Crankshaft 7 Exhaust valve (engine valve)
9 Exhaust camshaft (camshaft)
10 Fuel Injection Valve 12 Delivery Pipe 14 Fuel Tank 16 High Pressure Pump (Fuel Pump)
17 Pump drive cam 26 Spill control valve 42 Crank angle sensor (cam phase detection means)
45 Cam angle sensor (cam phase detection means)
50 Cam phase variable mechanism CAEX Exhaust cam phase (cam phase)
THEHPPSST Energized crank angle (operation timing)

Claims (1)

A fuel supply control device for an internal combustion engine that controls supply of fuel to an internal combustion engine having a cam phase variable mechanism that changes a cam phase that is a phase of a camshaft that drives an engine valve with respect to a crankshaft.
A fuel tank for storing fuel;
A fuel injection valve for supplying fuel to the combustion chamber of the internal combustion engine;
A delivery pipe for supplying pressurized fuel to the fuel injection valve;
A pump drive cam provided on the camshaft;
A fuel pump that is driven by the pump drive cam, sucks fuel from the fuel tank side, pressurizes the sucked fuel, and discharges the fuel to the delivery pipe side;
A spill control valve that operates at a predetermined operation timing during the pressurization of fuel by the fuel pump and controls the pressure of the fuel in the delivery pipe by recirculating the fuel from the fuel pump to the fuel tank side; ,
Cam phase detecting means for detecting the cam phase;
An operation timing setting means for setting the operation timing of the spill control valve according to the detected cam phase;
A fuel supply control apparatus for an internal combustion engine, comprising:

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