JP2006017048A - Fuel supply device and fuel pressure control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply device of an internal combustion engine capable of increasing-decreasing fuel pressure supplied to a fuel injection valve over a relatively wide range even when using gasoline as fuel; and a fuel pressure control device of the internal combustion engine capable of variably controlling the fuel pressure in such a way. <P>SOLUTION: This fuel supply device 10 of the internal combustion engine 3 has a main fuel chamber 13a for storing the fuel boosted by a high pressure pump P2, a sub-fuel chamber 17a for storing the fuel from the main fuel chamber 13a, a solenoid control valve 18 for controlling opening-closing of a communicating passage 16 between the two chambers 13a and 17a, and a low pressure relief valve 20 for releasing sub-fuel pressure Psub via a fuel return passage 19. An ECU 2 of a fuel pressure control device 1 controls the high pressure pump P2 in response to main fuel pressure Pmain (Step 27 and 34), and determines whether or not a pressure reducing condition of reducing the main fuel pressure Pmain is realized (Step 53), and opens the solenoid control valve 18 when the pressure reducing condition is realized, and closes the valve when the condition is not realized (Step 51 and 54). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel supply device for an internal combustion engine that supplies fuel to a fuel injection valve of an in-cylinder internal combustion engine and a fuel pressure control device for the internal combustion engine that controls the fuel pressure thereof.

  Conventionally, as a fuel supply device and a fuel pressure control device for an in-cylinder injection type internal combustion engine, those described in Patent Document 1 are known. The fuel supply device includes a fuel tank, a delivery pipe connected to the fuel tank via a fuel pipe, four fuel injection valves provided on the fuel tank, a low-pressure pump and a high-pressure pump provided on the fuel pipe, A fuel pipe for start-up extending between the fuel tank and the delivery pipe, and an evaporative fuel liquefying device, a check valve, a variable capacity device, an electromagnetic valve, etc. provided in this order on the start-up fuel pipe from the fuel tank side. is doing.

  This high-pressure pump is connected to the crankshaft of the internal combustion engine, and is driven by the crankshaft during operation of the internal combustion engine, and its discharge pressure is feedback-controlled by an ECU described later. In addition, the variable capacity device includes a diaphragm and a coil spring, and a variable capacity working chamber is formed by the diaphragm. In the fuel supply device, the evaporated fuel generated in the fuel tank is liquefied by the evaporated fuel liquefaction device and increased in pressure in the working chamber of the variable capacity device, and then passed through the opened solenoid valve and the starting fuel pipe. Supplied to the delivery pipe and stored. Further, after the internal combustion engine is started, the fuel is increased to a predetermined low pressure by the low pressure pump, and further increased to a predetermined high pressure by the high pressure pump, and in this state, the fuel is supplied to and stored in the delivery pipe. The high-pressure fuel stored in the delivery pipe is injected into the cylinder as the fuel injection valve is opened.

  The fuel pressure control device includes an ECU and a fuel pressure sensor that detects a discharge pressure of the high-pressure pump, that is, a fuel pressure in the delivery pipe. The ECU includes a solenoid that drives a diaphragm of the variable capacity device, A fuel pressure sensor, an ignition switch, a solenoid valve, a high pressure pump, and a low pressure pump are electrically connected to each other. In this fuel pressure control apparatus, the fuel pressure in the delivery pipe is controlled by the ECU as follows.

  First, based on the ON / OFF state of the ignition switch, it is determined whether or not the internal combustion engine is starting, and at the time of starting, the target fuel pressure is compared with the fuel pressure detected by the fuel pressure sensor. When the fuel pressure is lower than the target fuel pressure, energizing the solenoid expands the volume of the working chamber, sucks the fuel liquefied by the evaporated fuel liquefier into the working chamber, and then energizes the solenoid. Stop. Thereby, the volume of the working chamber is reduced, and the fuel in the working chamber is increased in pressure. When the electromagnetic valve is opened in this state, the fuel in the working chamber flows into the delivery pipe without returning to the evaporated fuel liquefaction device side by the check valve. As a result, the fuel pressure in the delivery pipe increases, and the fuel pressure necessary for fuel injection is ensured.

  Thereafter, when a predetermined time has elapsed from the start, the solenoid valve is closed, and the high-pressure pump is feedback-controlled based on the comparison result between the fuel pressure and the target fuel pressure. When the fuel pressure reaches the target fuel pressure, the solenoid valve is opened, the fuel in the delivery pipe flows into the working chamber, and the pulsation of the fuel pressure is eliminated by the biasing force of the coil spring. Further, when the ignition switch is turned off, the solenoid valve is once opened, the fuel in the delivery pipe is allowed to flow into the working chamber, and then the solenoid valve is closed, so that the high pressure fuel is supplied to the next internal combustion engine. Is stored in the working chamber for use in starting the engine.

JP 2002-310037 A

  In a cylinder injection internal combustion engine (hereinafter referred to as “gasoline engine”) using gasoline as fuel, a fuel supply device that can intentionally increase or decrease the fuel pressure supplied to the fuel injection valve during engine operation from the following viewpoints; A fuel pressure control device that can variably control the fuel pressure is desired. For example, from the viewpoint of avoiding the occurrence of smoke at a high load, it is desirable to shorten the opening time of the fuel injection valve. To achieve this, a considerably high fuel pressure is secured and supplied to the fuel injection valve. There is a need. In order to ensure a high output, for example, even when a supercharger is used, it is necessary to ensure a considerably high fuel pressure in order to increase the maximum fuel injection amount. On the other hand, if the amount of fuel to be injected by the fuel injection valve is very small, such as during low-load operation, there is a limit to shortening the opening time of the fuel injection valve in order to execute it accurately. It is desirable to reduce the pressure to an appropriate value.

  On the other hand, in the fuel supply device of Patent Document 1, since the check valve is provided between the variable capacity device and the fuel tank, for example, even if an attempt is made to depressurize the delivery pipe by opening the electromagnetic valve, Only the amount of fuel flowing into the working chamber can be depressurized, and the degree of depressurization becomes extremely small. In addition, since the fuel supply device is configured as such, in the fuel pressure control device of Patent Document 1, when the fuel pressure is controlled by opening and closing the electromagnetic valve, the control range is extremely small. Therefore, at the time of low load operation or the like, the fuel pressure cannot be reduced to an appropriate value, so that the control accuracy of the air-fuel ratio control is lowered and the operation state of the gasoline engine may become unstable. For the same reason, the penetration of fuel spray becomes larger than necessary, so that the amount of fuel adhering to the cylinder inner wall increases, thereby increasing the unburned HC and deteriorating the exhaust gas characteristics. In addition to this, if the penetration of the fuel spray becomes larger than necessary, the formation of the air-fuel mixture becomes inappropriate and the combustion efficiency is lowered.

  The present invention has been made in order to solve the above-described problem. A fuel supply device for an internal combustion engine capable of increasing and decreasing a fuel pressure supplied to a fuel injection valve in a relatively wide range even when gasoline is used as a fuel, and its An object of the present invention is to provide a fuel pressure control device for an internal combustion engine that can variably control the fuel pressure.

  In order to achieve the above object, an invention according to claim 1 is directed to an internal combustion engine that supplies fuel to a fuel injection valve 6 in a cylinder injection internal combustion engine 3 in which fuel is injected into the cylinder 3 a by the fuel injection valve 6. The fuel supply device 10 of the engine 3 includes a fuel storage chamber (fuel tank 11) that stores fuel, a fuel supply passage 12 that extends between the fuel storage chamber and the fuel injection valve 6, and a fuel supply passage 12. The fuel pump (high pressure pump P2) for increasing the pressure of the fuel and supplying the fuel to the fuel injection valve 6 side is provided between the fuel pump of the fuel supply passage 12 and the fuel injection valve 6, and the pressure is increased by the fuel pump. A main fuel chamber 13a that stores the generated fuel, a sub fuel chamber 17a that communicates with the main fuel chamber 13a via the communication passage 16 and stores fuel from the main fuel chamber 13a, and a control valve that controls opening and closing of the communication passage 16 (Electromagnetic control valve 18) and auxiliary fuel chamber 17a By opening the fuel return path 19 extending between the fuel storage chamber (fuel tank 11) and the fuel pressure (sub fuel pressure Psub) in the sub fuel chamber 17a exceeding a predetermined set pressure Psub_max, And a relief valve (low pressure relief valve 20) for opening the fuel return path 19.

  According to the fuel supply device for an internal combustion engine, the fuel stored in the fuel storage chamber is increased in pressure by the operation of the fuel pump and supplied to the main fuel chamber via the fuel supply path. The main fuel chamber communicates with the auxiliary fuel chamber via the communication passage, and the opening and closing of the communication passage is controlled by the control valve. Therefore, when the communication passage is closed by the control valve, The fuel is increased. On the other hand, when the communication path is opened by the control valve, the fuel in the main fuel chamber flows into the sub fuel chamber, so that the main fuel chamber is depressurized. Further, when the fuel pressure in the auxiliary fuel chamber exceeds a predetermined set pressure, the relief valve opens to open the fuel return path extending between the auxiliary fuel chamber and the fuel storage chamber. The fuel in the chamber is returned to the fuel storage chamber via the fuel return path, and thereby, the sub fuel chamber is depressurized to a predetermined set pressure. Therefore, by setting the pressure setting of the relief valve to an appropriate value, the fuel pressure in the main fuel chamber, that is, the fuel pressure supplied to the fuel injection valve can be quickly reduced to a lower value than before. Thus, the fuel pressure can be changed with a wider range of increase / decrease than before. As a result, when this fuel supply device is applied to a gasoline engine, the fuel pressure supplied to the fuel injection valve can be quickly reduced to an appropriate value during low load operation, etc. Control accuracy can be secured, and a stable operation state can be secured. For the same reason, it is possible to reduce the amount of fuel adhering to the inner wall of the cylinder by ensuring proper penetration in fuel spray, thereby reducing unburned HC and improving exhaust gas characteristics. In addition to this, by ensuring appropriate penetration in fuel spray, the air-fuel mixture can be formed in an appropriate state, and combustion efficiency can be improved.

  The invention according to claim 2 is the fuel pressure control device 1 of the internal combustion engine 3 having the fuel supply device 10 according to claim 1, and detects the main fuel pressure Pmain which is the fuel pressure in the main fuel chamber 13a. Main fuel pressure detection means (main fuel pressure sensor 37) and pump control means (ECU2, steps 27 and 34) for controlling the fuel pump (high pressure pump P2) in accordance with the detected main fuel pressure Pmain are detected. Based on the determination result of the depressurization condition determination means (ECU2, step 53) for determining whether or not the depressurization condition for depressurizing the main fuel pressure Pmain is satisfied according to the main fuel pressure Pmain, The control valve (electromagnetic control valve 18) is opened when the pressure reducing condition is satisfied (when the determination result at step 53 is YES), and is not satisfied (when the determination result at step 53 is NO). Valve control means (ECU 2 for closing the can), and step 51 and 54), characterized in that it comprises a.

  According to this internal combustion engine fuel pressure control device, the main fuel pressure detection means detects the main fuel pressure, which is the fuel pressure in the main fuel chamber, and the pump control means detects the fuel pressure according to the detected main fuel pressure. The pump is controlled, and the pressure reducing condition determining means determines whether or not a pressure reducing condition for reducing the main fuel pressure is established according to the detected main fuel pressure, and the valve control means determines the pressure reducing condition. Based on the determination result of the means, the control valve is opened when the pressure reducing condition is satisfied, and is closed when the pressure reducing condition is not satisfied. That is, when the depressurization condition is satisfied, the control valve is opened, so that the fuel in the main fuel chamber flows into the sub fuel chamber via the communication path, and the main fuel chamber is depressurized. On the other hand, when the pressure reducing condition for the main fuel pressure is not satisfied, the control valve is closed so that the fuel pressure is stored only in the main fuel chamber.

  In this case, as described above, in the fuel supply device according to the first aspect, the main fuel pressure can be quickly reduced to a value lower than the conventional one. The pressure can be quickly reduced to a lower value than before, whereby the main fuel pressure can be controlled with a wider control range than before. As a result, when this fuel pressure control device is applied to a gasoline engine, as described above, the fuel pressure supplied to the fuel injection valve can be quickly reduced to an appropriate value during low load operation or the like. In addition, good control accuracy in air-fuel ratio control can be secured, and a stable operation state can be secured. For the same reason, it is possible to reduce the amount of fuel adhering to the inner wall of the cylinder by ensuring proper penetration in fuel spray, thereby reducing unburned HC and improving exhaust gas characteristics. In addition to this, by ensuring appropriate penetration in fuel spray, the air-fuel mixture can be formed in an appropriate state, and combustion efficiency can be improved.

  Further, since the volume of the chamber for storing the fuel is controlled to be smaller than that at the time of depressurization at times other than the time of depressurization, the time required for the pressure increase of the fuel can be shortened. Work can be reduced. As a result, the operating efficiency of the internal combustion engine can be improved.

  According to a third aspect of the present invention, in the fuel pressure control device 1 for the internal combustion engine 3 according to the second aspect, the valve control means (ECU2) elapses a predetermined time (predetermined value Tcatlmt) from the end of the start of the internal combustion engine 3. Until this time, the control valve (electromagnetic control valve 18) is closed (step 28) regardless of the determination result of the decompression condition determination means.

  According to this fuel pressure control device for an internal combustion engine, the control valve is closed until a predetermined time elapses after the start of the internal combustion engine, regardless of the determination result of the pressure reducing condition determination means. By controlling the volume of the engine to a smaller value, it is possible to shorten the time required for the pressure increase of the fuel after the start of the internal combustion engine. As a result, after the start of the internal combustion engine, the fuel injection control can be executed with high accuracy and the stability of combustion can be ensured, thereby reducing the amount of unburned HC and smoke (PM) emissions. be able to.

  According to a fourth aspect of the present invention, in the fuel pressure control device 1 for the internal combustion engine 3 according to the second or third aspect, the auxiliary fuel pressure detecting means for detecting the auxiliary fuel pressure Psub which is the fuel pressure in the auxiliary fuel chamber 17a. Sub fuel pressure sensor 38) and pressure increasing condition determining means (ECU 2, step 50) for determining whether or not a pressure increasing condition for increasing the main fuel pressure Pmain is established according to the main fuel pressure Pmain. Further, the valve control means is provided when the main fuel pressure Pmain is lower than the sub fuel pressure Psub when the pressure increase condition is satisfied based on the determination result of the pressure increase condition determination means (the determination result of step 50 is When YES, the control valve is opened (step 51).

  According to this fuel pressure control device for an internal combustion engine, the sub fuel pressure, which is the fuel pressure in the sub fuel chamber, is detected by the sub fuel pressure detection means, and the main fuel pressure is detected by the pressure increase condition determination means according to the main fuel pressure. Whether or not a pressure increase condition for increasing the pressure is satisfied is determined, and when the pressure increase condition is satisfied based on the determination result of the pressure increase condition determination means by the valve control means, the main fuel pressure is When it is lower than the fuel pressure, the control valve is opened. As a result, the fuel in the auxiliary fuel chamber flows into the main fuel chamber and the main fuel pressure is increased, so that the main fuel pressure can be increased while using the auxiliary fuel pressure in addition to the fuel pump. The initial response in the pressure increase control can be improved. As a result, fuel injection control can be executed with higher accuracy, and better combustion stability can be ensured, thereby further reducing the amount of unburned HC and smoke (PM) emissions. it can.

  According to a fifth aspect of the present invention, in the fuel pressure control device 1 for an internal combustion engine 3 according to any one of the second to fourth aspects, a target main target that is a target of the main fuel pressure Pmain in accordance with the operating state of the internal combustion engine 3. Target main fuel pressure setting means (ECU2, steps 22, 23, 29 to 31, 32, 33) for setting the fuel pressure Pmain_cmd is further provided, and the valve control means is responsive to the main fuel regardless of the determination result of the pressure reducing condition determination means. When the absolute value of the deviation (following error e) between the pressure Pmain and the target main fuel pressure Pmain_cmd is less than the predetermined value e_fup (when the determination result of step 52 is YES), the control valve is opened (step 51). It is characterized by.

  According to this fuel pressure control apparatus for an internal combustion engine, the target main fuel pressure setting means sets the target main fuel pressure that is the target of the main fuel pressure according to the operating state of the internal combustion engine, and the valve control means reduces the pressure. Regardless of the determination result of the condition determination means, when the absolute value of the deviation between the main fuel pressure and the target main fuel pressure is less than a predetermined value, the control valve is opened. As a result, when the main fuel pressure is sufficiently controlled to a value close to the target main fuel pressure, the fuel in the main fuel chamber is filled into the sub fuel chamber, so that the fuel injection caused by the shortage of the main fuel pressure While avoiding a decrease in the control accuracy of the control, the auxiliary fuel chamber can be filled with high-pressure fuel to increase the auxiliary fuel pressure.

  The invention according to claim 6 is the fuel pressure control device 1 of the internal combustion engine 3 having the fuel supply device 10 according to claim 1, and detects the main fuel pressure Pmain which is the fuel pressure in the main fuel chamber 13a. Main fuel pressure detection means (main fuel pressure sensor 37) and target main fuel pressure setting means (ECU2, step) for setting a target main fuel pressure Pmain_cmd that is a target of the main fuel pressure Pmain according to the operating state of the internal combustion engine 3 22, 23, 29 to 31, 32, 33) and a control algorithm [Expressions (1) to (7)] including a predetermined two-degree-of-freedom control algorithm, the main fuel pressure Pmain follows the target main fuel pressure Pmain_cmd. As described above, the fuel pump (high pressure pump P2) and the control means (ECU 2) for controlling the control valve (electromagnetic control valve 18) are provided.

  According to the fuel pressure control apparatus for an internal combustion engine, the main fuel pressure, which is the fuel pressure in the main fuel chamber, is detected by the main fuel pressure detecting means, and the target main fuel pressure setting means is used according to the operating state of the internal combustion engine. The target main fuel pressure that is the target of the main fuel pressure is set, and the fuel pump and the fuel pump are controlled so that the main fuel pressure follows the target main fuel pressure by a control algorithm including a predetermined two-degree-of-freedom control algorithm by the control means. The control valve is controlled. In general, when fuel pressure control is performed using a fuel pump and a control valve, the fuel pressure tends to overshoot the target value due to the low response of the fuel pump and the control valve. The work of the fuel pump increases more than necessary. In contrast, in this fuel pressure control device, the fuel pump and the control valve are controlled so that the main fuel pressure follows the target fuel pressure by a control algorithm including a predetermined two-degree-of-freedom control algorithm. An overshoot of the fuel pressure with respect to the target main fuel pressure can be avoided, and the followability of the main fuel pressure to the target main fuel pressure can be improved. As a result, the work of the fuel pump can be reduced and the operating efficiency of the internal combustion engine can be improved.

  The invention according to claim 7 is the fuel pressure control device 1 of the internal combustion engine 3 having the fuel supply device 10 according to claim 1, and detects the main fuel pressure Pmain which is the fuel pressure in the main fuel chamber 13a. Main fuel pressure detection means (main fuel pressure sensor 37) and target main fuel pressure setting means (ECU2, step) for setting a target main fuel pressure Pmain_cmd that is a target of the main fuel pressure Pmain according to the operating state of the internal combustion engine 3 22, 23, 29 to 31, 32, 33) and the control algorithm [Expressions (1) to (7)] including a predetermined response assignment control algorithm, the main fuel pressure Pmain follows the target main fuel pressure Pmain_cmd. As described above, the fuel pump (high pressure pump P2) and the control means (ECU 2) for controlling the control valve (electromagnetic control valve 18) are provided.

  According to the fuel pressure control apparatus for an internal combustion engine, the main fuel pressure, which is the fuel pressure in the main fuel chamber, is detected by the main fuel pressure detecting means, and the target main fuel pressure setting means is used according to the operating state of the internal combustion engine. The target main fuel pressure that is the target of the main fuel pressure is set, and the fuel pump and the fuel pump are controlled so that the main fuel pressure follows the target main fuel pressure by the control means including a predetermined response designating control algorithm by the control means. The control valve is controlled. In such a fuel pressure control device, when the control valve is opened during operation of the fuel pump, the auxiliary fuel pressure applied to the main fuel chamber acts as a disturbance in the control of the main fuel pressure, and the main fuel pressure vibrates. Although it may become a state, as described above, the main fuel pressure is controlled by controlling the main fuel pressure by a control algorithm including a predetermined response-designated control algorithm. The main fuel pressure can be made to follow the target main fuel pressure while avoiding the vibration state. As a result, the control accuracy of the fuel injection control can be improved.

  In the invention according to claim 8, the fuel stored in the pressurized state in the fuel chamber (main fuel chamber 13a) is injected into the cylinder 3a via the fuel injection valve 6, and the fuel chamber (main fuel chamber 13a). In a cylinder injection internal combustion engine 3 having a fuel return passage 19 (communication passage 16, sub fuel chamber 17a) for returning the fuel in the fuel storage chamber (fuel tank 11), the fuel pressure (main fuel) in the fuel chamber A fuel pressure control device 1, 1A for the internal combustion engine 3 for controlling the pressure Pmain), a fuel pump (high pressure pump P2) for increasing the pressure of the fuel in the fuel storage chamber and supplying it to the fuel chamber, and a fuel return path 19 A control valve (electromagnetic control valve 18) for opening and closing (communication path 16, sub fuel chamber 17a), fuel pressure detecting means (main fuel pressure sensor 37) for detecting fuel pressure (main fuel pressure Pmain) in the fuel chamber, Detected fuel pressure (main fuel pressure Pmain) In response, the control means (ECU 2, step 27,28,34,35) for controlling the fuel pump (high-pressure pump P2) and the control valve (electromagnetic control valve 18) and, characterized in that it comprises a.

  According to this fuel pressure control apparatus for an internal combustion engine, the fuel pressure in the fuel chamber is detected by the fuel pressure detection means, and the fuel pump and the control valve are controlled by the control means in accordance with the detected fuel pressure. Since the fuel return path is opened and closed by the control valve, when fuel pressure reduction control is executed, the fuel pressure is quickly reduced to a lower value than before by opening the fuel return path via the control valve. Thus, the fuel pressure can be controlled with a wider control range than before. As a result, when this fuel pressure control device is applied to a gasoline engine, as described above, the fuel pressure supplied to the fuel injection valve can be quickly reduced to an appropriate value during low load operation or the like. In addition, good control accuracy in air-fuel ratio control can be secured, and a stable operation state can be secured. For the same reason, it is possible to reduce the amount of fuel adhering to the inner wall of the cylinder by ensuring proper penetration in fuel spray, thereby reducing unburned HC and improving exhaust gas characteristics. In addition to this, by ensuring appropriate penetration in fuel spray, the air-fuel mixture can be formed in an appropriate state, and combustion efficiency can be improved.

  According to a ninth aspect of the present invention, in the fuel pressure control device 1, 1 </ b> A for the internal combustion engine 3 according to the eighth aspect, the target that is the target of the fuel pressure (main fuel pressure Pmain) according to the operating state of the internal combustion engine 3. Target fuel pressure setting means (ECU2, steps 22, 23, 29 to 31, 32, 33) for setting fuel pressure (target main fuel pressure Pmain_cmd) is further provided, and the control means includes a predetermined two-degree-of-freedom control algorithm. According to the control algorithm [Equations (1) to (7)], the fuel pump (high pressure pump P2) and the control valve (the main fuel pressure Pmain) follow the target fuel pressure (target main fuel pressure Pmain_cmd). The electromagnetic control valve 18) is controlled.

  As described above, in general, when fuel pressure control is performed using a fuel pump and a control valve, the fuel pressure overshoots the target value due to low response of the fuel pump and control valve. As a result, the work of the fuel pump increases more than necessary. In contrast, in this fuel pressure control device, the fuel pump and the control valve are controlled by a control algorithm including a predetermined two-degree-of-freedom control algorithm so that the fuel pressure follows the target fuel pressure. Overshoot of the target fuel pressure can be avoided, and the followability of the fuel pressure to the target fuel pressure can be improved. As a result, the work of the fuel pump can be reduced and the operating efficiency of the internal combustion engine can be improved.

  According to a tenth aspect of the present invention, in the fuel pressure control device 1, 1 </ b> A of the internal combustion engine 3 according to the eighth aspect, a target that is a target of the fuel pressure (main fuel pressure Pmain) according to the operating state of the internal combustion engine 3. Target fuel pressure setting means (ECU2, steps 22, 23, 29 to 31, 32, 33) for setting the fuel pressure (target main fuel pressure Pmain_cmd) is further provided, and the control means includes a predetermined response designating control algorithm. According to the control algorithm [Equations (1) to (7)], the fuel pump (high pressure pump P2) and the control valve (the main fuel pressure Pmain) follow the target fuel pressure (target main fuel pressure Pmain_cmd). The electromagnetic control valve 18) is controlled.

  According to the fuel pressure control apparatus for an internal combustion engine, the target fuel pressure setting means sets the target fuel pressure that is the target of the fuel pressure according to the operating state of the internal combustion engine, and the control means sets the predetermined response designation type. The fuel pump and the control valve are controlled by the control algorithm including the control algorithm so that the fuel pressure follows the target fuel pressure. Therefore, when the control valve is opened during operation of the fuel pump, even if the fuel pressure may be in a vibration state, by controlling the fuel pressure by a control algorithm including a predetermined response assignment type control algorithm, The fuel pressure can be made to follow the target fuel pressure while avoiding the fuel pressure from oscillating. As a result, the control accuracy of the fuel injection control can be improved.

  Hereinafter, a fuel supply device and a fuel pressure control device for an internal combustion engine according to a first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 2, the fuel pressure control device 1 includes an ECU 2. The ECU 2 controls the fuel pressure according to the operating state of an internal combustion engine (hereinafter referred to as “engine”) 3 as will be described later. Various control processes such as are executed.

  As shown in FIG. 1, the engine 3 is an in-line four-cylinder gasoline engine having four sets of cylinders 3a and pistons 3b (only one set is shown), and is mounted on a vehicle (not shown). The intake pipe 4 of the engine 3 is provided with an air flow sensor 30 and a throttle valve mechanism 5 in order from the upstream side. The air flow sensor 30 is constituted by a hot-wire air flow meter, and outputs a detection signal representing the flow rate (hereinafter referred to as “air flow rate”) Gth of the air flowing through the intake pipe 4 to the ECU 2.

  The throttle valve mechanism 5 includes a throttle valve 5a and a TH actuator 5b that opens and closes the throttle valve 5a. The throttle valve 5a is rotatably provided in the middle of the intake pipe 4, and changes the air flow rate Gth by changing the opening degree associated with the rotation. The TH actuator 5b is a combination of a motor connected to the ECU 2 and a gear mechanism (both not shown), and is controlled by a control signal from the ECU 2 to change the opening of the throttle valve 5a.

  The throttle valve 5a is provided with two springs (both not shown) for biasing the throttle valve 5a in the valve opening direction and the valve closing direction, respectively, and the throttle valve 5a is biased by the biasing force of the two springs. Is maintained at a predetermined initial opening when no control signal is input to the TH actuator 5b. The initial opening is set to a value (for example, 6 °) that is close to the fully closed state and that can secure an intake air amount necessary for starting the engine 3.

  Further, in the vicinity of the throttle valve 5a of the intake pipe 4, there is provided a throttle valve opening sensor 31 constituted by, for example, a potentiometer. The throttle valve opening sensor 31 outputs to the ECU 2 a detection signal indicating the opening TH of the throttle valve 5a (hereinafter referred to as “throttle valve opening”) TH.

  In addition, an intake pipe absolute pressure sensor 32 and an intake air temperature sensor 33 are provided in a portion of the intake pipe 4 on the downstream side of the throttle valve 5a. The intake pipe absolute pressure sensor 32 is constituted by, for example, a semiconductor pressure sensor, and outputs a detection signal representing the absolute pressure (hereinafter referred to as “intake pipe absolute pressure”) PBA in the intake pipe 4 to the ECU 2. Further, the intake air temperature sensor outputs a detection signal representing the temperature TA (hereinafter referred to as “intake air temperature”) TA flowing through the intake pipe 4 to the ECU 2.

  On the other hand, the engine 3 is provided with a crank angle sensor 34 and a water temperature sensor 35. The crank angle sensor 34 outputs a CRK signal and a TDC signal, both of which are pulse signals, to the ECU 2 as the crankshaft 3c rotates. The CRK signal is output at one pulse every predetermined crank angle (for example, 30 °), and the ECU 2 calculates the engine speed (hereinafter referred to as “engine speed”) NE of the engine 3 based on the CRK signal. The TDC signal is a signal indicating that the piston 3b of each cylinder 3a is at a predetermined crank angle position slightly before the TDC position of the intake stroke, and one pulse is output for each predetermined crank angle.

  The water temperature sensor 35 includes a thermistor attached to the cylinder block of the engine 3 and outputs a detection signal representing the engine water temperature TW, which is the temperature of the cooling water circulating in the cylinder block, to the ECU 2.

  Further, the cylinder head of the engine 3 is provided with a fuel injection valve 6 and a spark plug 7 for each cylinder 3a. Each fuel injection valve 6 is attached to the cylinder head in an inclined state so as to inject fuel directly into the combustion chamber of the cylinder 3a. That is, the engine 3 is configured as a cylinder injection engine. The fuel injection valve 6 is electrically connected to the ECU 2 and is controlled by the ECU 2 to inject fuel at a valve opening time and a valve opening timing corresponding to a fuel injection time Tcyl described later.

  Each spark plug 7 is also electrically connected to the ECU 2, and the discharge state is controlled by the ECU 2 so that the air-fuel mixture in the fuel chamber is combusted at a timing corresponding to an ignition timing Iglog described later.

  On the other hand, the exhaust pipe 8 of the engine 3 is provided with a LAF sensor 36 upstream of a catalyst device (not shown). The LAF sensor 36 is composed of zirconia and a platinum electrode, and the oxygen concentration in the exhaust gas flowing in the exhaust pipe 8 is measured in a wide range of air-fuel ratios from a rich region richer than the stoichiometric air-fuel ratio to an extremely lean region. It detects linearly and outputs a detection signal representing it to the ECU 2. The ECU 2 calculates a detected air-fuel ratio KACT representing the air-fuel ratio in the exhaust gas based on the value of the detection signal of the LAF sensor 36. The detected air-fuel ratio KACT is specifically calculated as an equivalence ratio.

  Next, the fuel supply apparatus 10 of this embodiment will be described. The fuel supply device 10 supplies high-pressure fuel (gasoline) to the fuel injection valve 6, and as shown in FIG. 3, a fuel tank 11 (fuel storage chamber) and a fuel supply path 12 are provided therethrough. Connected to the main delivery pipe 13 and the like.

  The fuel supply path 12 is provided with a low pressure pump P1 and a high pressure pump P2. The low-pressure pump P <b> 1 is an electric pump type whose operation is controlled by the ECU 2, and is disposed in the fuel tank 11. The low-pressure pump P1 is always operated during the operation of the engine 3, and the fuel in the fuel tank 11 is increased to a predetermined pressure (for example, 0.5 MPa), discharged to the high-pressure pump P2, and excess fuel is returned to the return path 12a. To return to the fuel tank 11.

  The high-pressure pump P2 (fuel pump) further increases the pressure of the fuel from the low-pressure pump P1 and discharges the fuel to the main delivery pipe 13 side. The high-pressure pump P2 (fuel pump) incorporates an electromagnetic clutch (not shown) through the electromagnetic clutch. Are connected to the crankshaft 3c. This electromagnetic clutch is connected to the ECU 2 and is engaged / disengaged by a control signal from the ECU 2 and its engagement force is controlled. Thereby, as will be described later, the operation of the high-pressure pump P2 is controlled, and the pressure increase state of the fuel by the high-pressure pump P2 is controlled.

  On the other hand, the main delivery pipe 13 has a main fuel chamber 13a (fuel chamber) in which the internal space stores the fuel from the high pressure pump P2 in a high pressure state. The main delivery pipe 13 is provided with the above-described four fuel injection valves 6 and the main fuel pressure sensor 37. By opening these fuel injection valves 6, the fuel in the main fuel chamber 13a is transferred to the combustion chamber. Is injected into.

  The main fuel pressure sensor 37 is connected to the ECU 2 to detect the main fuel pressure Pmain, which is the fuel pressure in the main fuel chamber 13a, and outputs a detection signal representing it to the ECU 2. In the present embodiment, the main fuel pressure sensor 37 corresponds to a main fuel pressure detecting means and a fuel pressure detecting means.

  Further, the main delivery pipe 13 is connected to the fuel tank 11 via a fuel return path 14, and a high pressure relief valve 15 is provided in the fuel return path 14. The high-pressure relief valve 15 is a mechanical type, and opens when the main fuel pressure Pmain exceeds a predetermined set pressure Pmain_max (for example, 50 MPa) by the operation of the high-pressure pump P2. Thereby, the fuel in the main fuel chamber 13a is returned to the fuel tank 11, and the main fuel pressure Pmain is reduced to a predetermined set pressure Pmain_max.

  The main delivery pipe 13 is connected to a sub delivery pipe 17 via a communication passage 16, and the internal space of the sub delivery pipe 17 serves as a sub fuel chamber 17 a for storing fuel from the main delivery pipe 13. Yes.

  An electromagnetic control valve 18 is provided in the communication path 16 (fuel return path). The electromagnetic control valve 18 (control valve) is connected to the ECU 2 and its opening degree is controlled by the ECU 2 as will be described later. By opening the electromagnetic control valve 18, the fuel in the main fuel chamber 13a flows into the auxiliary fuel chamber 17a and is stored.

  A sub fuel pressure sensor 38 is attached to the sub delivery pipe 17 (fuel return path). The sub fuel pressure sensor 38 (sub fuel pressure detecting means) is connected to the ECU 2, detects the sub fuel pressure Psub, which is the fuel pressure in the sub fuel chamber 17a, and outputs a detection signal representing it to the ECU 2. .

  Further, the auxiliary delivery pipe 17 is connected to the fuel tank 11 through a fuel return path 19, and a low pressure relief valve 20 is provided in the fuel return path 19. The low pressure relief valve 20 (relief valve) is a mechanical type, and is opened when the auxiliary fuel pressure Psub exceeds a predetermined set pressure Psub_max (for example, 20 MPa) due to the opening of the electromagnetic control valve 18 or the like. To do. As a result, the fuel in the auxiliary fuel chamber 17a is returned to the fuel tank 11, and the auxiliary fuel pressure Psub is reduced to a predetermined set pressure Psub_max.

  With the above configuration, in the fuel supply device 10, the main fuel pressure Pmain has a predetermined set value Pmain_max as an upper limit depending on the operating state of the high-pressure pump P2, the open / close state of the electromagnetic control valve 18, and the open / close state of the fuel injection valve 6. It is changed within the range. Further, the auxiliary fuel pressure Psub is increased with the predetermined set value Psub_max as an upper limit by opening the electromagnetic control valve 18. Further, as will be described later, the ECU 2 controls the main fuel pressure Pmain and the sub fuel pressure Psub.

  On the other hand, as shown in FIG. 2, an accelerator opening sensor 39, a battery voltage sensor 40, and an ignition switch (hereinafter referred to as “IG · SW”) 41 are connected to the ECU 2. The accelerator opening sensor 39 outputs to the ECU 2 a detection signal indicating the depression amount (hereinafter referred to as “accelerator opening”) AP of an accelerator pedal (not shown) of the vehicle.

  Further, the battery voltage sensor 40 outputs a detection signal representing a battery voltage (hereinafter referred to as “battery voltage”) VB (not shown) to the ECU 2, and the IG / SW 41 is turned on / off by operating an ignition key (not shown). In addition, a signal indicating the ON / OFF state is output to the ECU 2.

  The ECU 2 is composed of a microcomputer comprising a CPU, RAM, ROM, I / O interface (all not shown), and the detection signals of the various sensors 30 to 40 described above and ON / OFF of the IG / SW 41. In accordance with the signal or the like, the operating state of the engine 3 is determined and various controls are executed. Specifically, the main fuel pressure Pmain and the auxiliary fuel pressure Psub are controlled via the high pressure pump P2 and the electromagnetic control valve 18. Further, the intake air amount is controlled via the throttle valve mechanism 5, and fuel injection control and ignition timing control are executed via the fuel injection valve 6 and the spark plug 7, respectively.

  In this embodiment, the ECU 2 corresponds to a pump control unit, a pressure reduction condition determination unit, a valve control unit, a pressure increase condition determination unit, a target main fuel pressure setting unit, a control unit, and a target fuel pressure setting unit.

  Hereinafter, various control processes executed by the ECU 2 will be described. FIG. 4 shows a control process in which an interrupt is executed at a predetermined cycle ΔTk (for example, 5 msec) by setting the program timer. In this process, as shown in the figure, first, in step 1 (abbreviated as “S1” in the figure, the same applies hereinafter), intake air amount control is executed as described later, and then in step 2, described later. As described above, after the fuel pressure control is executed, the present process is terminated.

  Next, the intake air amount control process described above will be described with reference to FIG. As described below, this process controls the intake air amount by controlling the throttle valve opening TH. In this process, first, in step 10, it is determined whether or not a throttle valve failure flag F_THNG is “1”. The throttle valve failure flag F_THNG is set to “1” when it is determined that the throttle valve mechanism 5 has failed in a failure determination process (not shown), and is set to “0” when it is determined to be normal. .

  If the determination result in step 10 is NO and the throttle valve mechanism 5 is normal, the process proceeds to step 11 to determine whether or not the engine start flag F_ENGSTART is “1”.

  The engine start flag F_ENGSTART is set in a determination process (not shown) by determining whether engine start control is being performed, that is, cranking, according to the output signal of the engine speed NE and the IG / SW 41. Specifically, “1” is set when the engine start control is being performed, and “0” is set otherwise.

  When the determination result in step 11 is YES and the engine start control is being performed, the process proceeds to step 12 where the target opening TH_cmd is calculated by searching the table shown in FIG. 6 based on the engine water temperature TW. In this table, the target opening TH_cmd is set to a larger value as the engine water temperature TW is lower in the range where the engine water temperature TW is higher than the predetermined value TWREF1, and to the predetermined value THref in the range of TW ≦ TWREF1. Is set. This is because the friction of the engine 3 increases when the water temperature is low, to cope with this.

  Next, the routine proceeds to step 13, where a feedback control process for the throttle valve opening TH is executed. Specifically, the throttle valve mechanism 5 is moved to the throttle valve mechanism 5 by a predetermined feedback control algorithm (for example, a target value filter type two-degree-of-freedom sliding mode control algorithm described later) so that the throttle valve opening TH follows the target opening TH_cmd. The value of the control signal is calculated. Thereby, feedback control is performed so that the throttle valve opening TH follows the target opening TH_cmd. Then, this process is complete | finished.

  On the other hand, if the determination result in step 11 is NO and the engine start control is not being performed, the process proceeds to step 14 to determine whether or not the accelerator opening AP is smaller than a predetermined value APREF. The predetermined value APREF is for determining that the accelerator pedal is not depressed, and is set to a value (for example, 1 °) that can determine that the accelerator pedal is not depressed.

  If the decision result in the step 14 is YES and the accelerator pedal is not depressed, the process proceeds to a step 15 in which the catalyst warm-up control execution time Tcat (timed value of elapsed time immediately after the start of the engine 3) is a predetermined value Tcatlmt. It is determined whether it is less than (predetermined time; for example, 30 sec). This catalyst warm-up control is for rapidly activating the catalyst in the catalyst device provided in the exhaust pipe 8 after the engine is started.

  When the determination result in step 15 is YES, it is determined that the catalyst warm-up control should be executed, and the process proceeds to step 16 where the target opening TH_cmd is set according to the catalyst warm-up control execution time Tcat and the engine water temperature TW. This is calculated by searching the map shown in FIG. In the figure, TW1 to TW3 indicate predetermined values of the engine coolant temperature TW that satisfy the relationship of TW1 <TW2 <TW3.

  In this map, the target opening TH_cmd is set to a larger value as the engine coolant temperature TW is lower. This is because the lower the engine water temperature TW, the longer the time required for the activation of the catalyst. Therefore, by increasing the exhaust gas volume, the time required for the activation of the catalyst is shortened. In addition, in this map, the target opening TH_cmd is set to a larger value as the execution time Tcat is longer while the execution time Tcat of the catalyst warm-up control is shorter, and after the execution time Tcat has passed to some extent. Is set to a smaller value as the execution time Tcat is longer. This is because when the engine 3 warms up as the execution time Tcat elapses and the friction decreases, the ignition timing is used to maintain the engine speed NE at the target value unless the intake air amount is reduced. This is to avoid the excessively retarded control and the combustion state becoming unstable.

  Next, after executing step 13 as described above, the present process is terminated.

  On the other hand, when the determination result of step 14 or step 15 is NO, that is, when the engine start control is not being performed, when the accelerator pedal is depressed, or when Tcat ≧ Tcatlmt, the routine proceeds to step 17, and the target opening TH_cmd Is calculated by searching the map shown in FIG. 8 according to the engine speed NE and the accelerator pedal opening AP. In the figure, AP1 to AP3 indicate predetermined values of the accelerator opening AP at which the relationship of AP1 <AP2 <AP3 is established, and this also applies to the following description.

  In this map, the target opening TH_cmd is set to a larger value as the engine speed NE is higher or the accelerator opening AP is larger. This is because the higher the engine speed NE or the greater the accelerator pedal opening AP, the greater the required output for the engine 3 and the greater the required intake air amount.

  Next, after executing step 13 as described above, the present process is terminated.

  On the other hand, if the decision result in the step 10 is YES and the throttle valve mechanism 5 is out of order, the process proceeds to a step 18 to stop the feedback control of the throttle valve opening TH. That is, the output of the control signal to the TH actuator 5b of the throttle valve mechanism 5 is stopped. As a result, the throttle valve opening TH is maintained at the predetermined initial opening described above. Then, this process is complete | finished.

  Next, the above-described fuel pressure control process will be described with reference to FIG. This process controls the main fuel pressure Pmain and the sub fuel pressure Psub by controlling the high pressure pump P2 and the electromagnetic control valve 18, as described below. In this process, first, in steps 20 and 21, the values of the main fuel pressure Pmain and the sub fuel pressure Psub stored in the RAM are read. That is, the values of Pmain and Psub are sampled. The values of the main fuel pressure Pmain and the sub fuel pressure Psub are calculated in the fuel injection control process as will be described later.

  Next, the routine proceeds to step 22 where it is determined whether or not the engine start flag F_ENGSTART described above is “1”. If the determination result is YES and the engine start control is being performed, the routine proceeds to step 23, where the target main fuel pressure Pmain_cmd is set to a predetermined start time value Pmain_st. The predetermined start time value Pmain_st is set to a value (for example, 2 MPa) that can ensure a good balance between shortening of the engine start time and fuel spray suitable for engine start.

  Next, the routine proceeds to step 24, where it is determined whether or not the main fuel pressure Pmain is equal to or higher than the target main fuel pressure Pmain_cmd. When the determination result is YES, a main fuel pressure securing flag F_Pmain_OK is set to “1” in step 25 in order to indicate that the main fuel pressure Pmain capable of appropriately performing fuel injection is secured.

  On the other hand, when the determination result in step 24 is NO, the main fuel pressure securing flag F_Pmain_OK is set to “0” in step 26 in order to indicate that the main fuel pressure Pmain capable of appropriately performing fuel injection is not secured. Set.

  In step 27 following step 25 or 26, a pump control input Upump is calculated. The pump control input Upump is for controlling the high pressure pump P2, and the operation of the high pressure pump P2 is controlled by inputting a control signal corresponding to the value of the pump control input Upump to the high pressure pump P2. The Specifically, the pump control input Upump is calculated as shown in FIG.

  As shown in the figure, first, at step 40, the control input Usl is calculated by a target value filter type two-degree-of-freedom sliding mode control algorithm expressed by the following equations (1) to (7). In addition, each discrete data with the symbol (k) in the following formulas (1) to (7) indicates that the data is sampled (or calculated) in synchronization with the predetermined period ΔTk described above, and the symbol k Represents the order of the sampling cycle of each discrete data. For example, the symbol k indicates a value sampled at the current control timing, and the symbol k-1 indicates a value sampled at the previous control timing. This also applies to the following discrete data. In the following description, the symbol (k) and the like in each discrete data is omitted as appropriate.

  In the above equation (1), Ueq is an equivalent control input and is calculated by equation (2). In the equation (2), Pmain_cmd_f is a filter value of the target main fuel pressure Pmain_cmd, and is calculated by a first-order lag filter algorithm shown in equation (7). In Equation (7), POLE_f is a target value filter setting parameter that is set so that the relationship of -1 <POLE_f <0 is established. In equation (2), a1, a2, and b1 are model parameters of the model shown in equation (8) described later, and POLE is a response designation that is set so that the relationship of −1 <POLE <0 is established. It is a parameter.

  Moreover, in Formula (1), Urch is a reaching law input and is calculated by Formula (3). In Equation (3), Krch is a predetermined reaching law gain, and σ is a switching function calculated by Equation (5). In equation (5), e is a tracking error (deviation) defined as in equation (6). Further, in equation (1), Uadp is an adaptive law input and is calculated by equation (4). In the equation (4), Kadp is a predetermined adaptive law gain. From the above formulas (1) to (7), the control input Usl is calculated as a value within the range of −1 ≦ Usl ≦ 1.

The above formulas (1) to (7) define a model representing the relationship between the dynamic characteristics of the main fuel pressure Pmain and the control input Usl as the following formula (8). Based on this model, the engine speed It is derived by applying a target value filter type two-degree-of-freedom sliding mode control law so that the number NE converges to the target rotational speed NE_cmd.
Pmain (k + 1) = a1 · Pmain (k) + a2 · Pmain (k−1)
+ B1 · Usl (k) (8)

  After calculating the control input Usl in step 40 as described above, the process proceeds to step 41, where it is determined whether or not the control input Usl calculated in step 40 is greater than 0. When the determination result is YES, it is determined that the high-pressure pump P2 is to be operated, that is, the pressure-increasing control is to be executed, and the process proceeds to step 42 and the pump control input Uppump is set to the control input Usl. finish. As a result, the operation of the high-pressure pump P2 is feedback-controlled so that the main fuel pressure Pmain follows the target main fuel pressure Pmain_cmd.

  In this case, Usl> 0 is satisfied when σ (k) = e (k) + POLE · e (k) <0 is satisfied. For example, the target main fuel pressure Pmain_cmd is higher than the main fuel pressure Pmain. In the case of the pressure increase control set to the value, Pmain <Pmain_cmd_f is established. Further, when Usl = 1, that is, when Upump = 1, the work of the high-pressure pump P2 is maximized.

  On the other hand, when the determination result in step 41 is NO, it is determined that the high pressure pump P2 is to be stopped, and the process proceeds to step 43, the pump control input Upump is set to the value 0, and the present process is terminated. Thereby, the high-pressure pump P2 is stopped.

  Returning to FIG. 9, after calculating the pump control input Upump as described above in step 27, the process proceeds to step 28, and the valve control input Usol is set to 0. The valve control input Usol is for controlling the electromagnetic control valve 18. When a control signal corresponding to the value of the valve control input Usol is input to the electromagnetic control valve 18, the electromagnetic control valve 18 is opened. The degree is controlled. Specifically, when Usol = 0, the electromagnetic control valve 18 is controlled to be fully closed, and the communication path 16 is closed. After executing step 28 in this way, the present process is terminated.

  On the other hand, when the determination result of step 22 is NO and the engine start control is not being performed, the routine proceeds to step 29, where it is determined whether or not the accelerator opening AP is smaller than the predetermined value APREF. If the determination result is YES and the accelerator pedal is not depressed, the routine proceeds to step 30, where it is determined whether or not the catalyst warm-up control execution time Tcat is smaller than the predetermined value Tcatlmt described above.

  When the determination result is YES, it is determined that the catalyst warm-up control should be executed, and the process proceeds to step 31 where the target main fuel pressure Pmain_cmd is set to a predetermined catalyst warm-up control value Pmain_ast. The predetermined catalyst warm-up control value Pmain_ast is set to a value (for example, 20 MPa) of the main fuel pressure Pmain that can ensure a stable combustion state during execution of the ignition timing retard control in the catalyst warm-up control.

  Next, as described above, after executing steps 27 and 28, the present process is terminated.

  On the other hand, when the determination result of step 29 or step 30 is NO, that is, when the engine start control is not being performed, when the accelerator pedal is depressed, or when Tcat ≧ Tcatlmt, the routine proceeds to step 32 where the engine speed NE is reached. The normal operation value Pmain_map is calculated by searching the map shown in FIG. 11 according to the accelerator opening AP.

  In this map, the normal operation value Pmain_map is set to a larger value as the engine speed NE is higher or the accelerator pedal opening AP is larger. This is because the higher the engine speed NE or the greater the accelerator pedal opening AP, the greater the required output for the engine 3 and thus the higher the main fuel pressure Pmain is required.

  In step 33 following step 32, the target main fuel pressure Pmain_cmd is set to the normal operation value Pmain_map. Next, the process proceeds to step 34, and the pump control input Upump is calculated by the calculation process shown in FIG.

  Next, the routine proceeds to step 35, where the valve control input Usol is calculated. The calculation of the valve control input Usol is specifically executed as shown in FIG.

  As shown in the figure, first, in step 50, it is determined whether or not DPmain_cmd_f> 0 and Pmain <Psub are both established. These conditions represent conditions for executing the assist mode in which the main fuel pressure Pmain is increased by introducing the auxiliary fuel pressure Psub into the main fuel chamber 13a. This DPmain_cmd_f is calculated as a deviation [Pmain_cmd_f (k) −Pmain_cmd_f (k−1)] between the current value and the previous value of the filter value of the target main fuel pressure. That is, when the filter value Pmain_cmd_f of the target main fuel pressure is in the increasing direction and the increase control of the main fuel pressure Pmain is executed, the execution condition of the assist mode is set when the sub fuel pressure Psub is higher than the main fuel pressure Pmain. Is determined to be true.

  If the determination result in step 50 is YES and the assist mode execution condition is satisfied, the process proceeds to step 51, the valve control input Usol is set to the value 1, and the process is terminated. When Usol is set to the value 1 in this way, the electromagnetic control valve 18 is controlled to be fully opened.

  On the other hand, if the determination result in step 50 is NO and the execution condition of the assist mode is not satisfied, the process proceeds to step 52, and whether or not | e | <e_fup, Psub <Psub_cmd and Pmain> Pmain_mset are all satisfied. Is determined. These conditions represent the execution conditions of the filling mode in which the auxiliary fuel pressure Psub is increased by introducing the main fuel pressure Pmain into the auxiliary fuel chamber 17a.

  Specifically, e_fup is a predetermined threshold value, and whether or not the absolute value | e | of the tracking error is a considerably small value, that is, the main fuel pressure Pmain is very close to the target main fuel pressure Pmain_cmd. It is set to a value (for example, 1 MPa) that can determine whether or not there is. Pmain_mset is a predetermined value (for example, 20 Mpa) of the main fuel pressure Pmain capable of executing the filling mode, and Psub_cmd is a predetermined target value (for example, 16 MPa) of the auxiliary fuel pressure Psub.

  When the determination result in step 52 is YES and the execution condition for the filling mode is satisfied, as described above, after executing step 51, the present process is terminated. As a result, the electromagnetic control valve 18 is controlled to be fully opened, and the main fuel pressure Pmain is introduced into the sub fuel chamber 17a, thereby increasing the sub fuel pressure Psub.

  On the other hand, if the determination result in step 52 is NO and the execution condition for the filling mode is not satisfied, the process proceeds to step 53, where it is determined whether or not Usl <Usl_dec and Pmain> Pmain_mset are both satisfied. These conditions represent the execution conditions of the decompression mode in which the main fuel pressure Pmain is reduced by introducing the main fuel pressure Pmain into the sub fuel chamber 17a.

  Specifically, Usl_dec is a predetermined threshold value, and is set to a value (for example, a value of −0.3) that can determine whether or not the value of the switching function σ is considerably larger than the value 0. That is, Usl <Usl_dec is satisfied when σ >> 0 is satisfied. For example, when the target main fuel pressure Pmain_cmd is set to a value lower than the main fuel pressure Pmain, the degree of divergence between the two Is when is big.

  If the determination result in step 53 is YES and the execution condition of the decompression mode is satisfied, as described above, after executing step 51, the present process is terminated. As a result, the electromagnetic control valve 18 is controlled to be fully opened, so that the main fuel pressure Pmain is introduced into the auxiliary fuel chamber 17a via the communication passage 16 and reduced.

  On the other hand, when the determination result of step 53 is NO, that is, when the execution conditions of the assist mode, the filling mode, and the pressure reduction mode are not satisfied, the process proceeds to step 54 and the valve control input Usol is set to 0. This process is terminated. Thereby, the electromagnetic control valve 18 is controlled to be fully closed.

  Returning to FIG. 9, in step 35, after calculating the valve control input Usol as described above, the present process is terminated.

  Next, control processing executed in synchronization with the generation timing of the TDC signal will be described with reference to FIG. As shown in the figure, in this process, first, in step 60, it is determined whether or not the main fuel pressure securing flag F_Pmain_OK is “1”.

  When the determination result is YES and the main fuel pressure Pmain at which fuel injection can be appropriately executed is ensured, the process proceeds to step 61, and fuel injection control processing is executed as described later. Next, the routine proceeds to step 62, where the ignition timing control process is executed as will be described later, and then this process ends.

  On the other hand, when the determination result in step 60 is NO and the main fuel pressure Pmain that can appropriately execute fuel injection is not secured, the process proceeds to step 63, and after stopping the fuel injection control process and the ignition timing control process, End the process. Thereby, fuel injection by the fuel injection valve 6 and ignition by the spark plug 7 are stopped.

  Next, the fuel injection control process will be described with reference to FIG. In this process, as described below, the fuel injection time Tcyl is calculated for each cylinder 3a, that is, for each fuel injection valve 6.

First, at step 70, the main fuel pressure Pmain is calculated by the following equation (9).
Pmain = [Pmain '(m) + Pmain' (m-1) + ...... + Pmain '(m-w + 1)] / w (9)
Here, Pmain 'indicates a sampling value of the main fuel pressure sampled in synchronization with the generation timing of the CRK signal based on the detection signal of the main fuel pressure sensor 37, and w is a positive predetermined value (for example, Value 6). The symbol (m) represents the sampling order of each discrete data.

  As shown in the above equation (9), the main fuel pressure Pmain is calculated as a moving average value of the sampling value Pmain '. This is because the main fuel pressure Pmain is appropriately calculated while avoiding the influence even when the main fuel pressure Pmain fluctuates due to fluctuations in the discharge pressure of the high-pressure pump P2. The main fuel pressure Pmain calculated in this way is stored in the RAM and read out during the fuel pressure control process as described above.

In step 71 following step 70, the auxiliary fuel pressure Psub is calculated by the following equation (10).
Psub = [Psub '(m) + Psub' (m-1) + ...... + Psub '(m-w + 1)] / w (10)
Here, Psub ′ represents a sampling value of the auxiliary fuel pressure sampled in synchronization with the generation of the CRK signal based on the detection signal of the auxiliary fuel pressure sensor 38.

  As shown in the above equation (10), the auxiliary fuel pressure Psub is calculated as a moving average value of the sampling value Psub '. This is because the sub fuel pressure Psub is appropriately calculated while avoiding the influence even when the sub fuel pressure Psub fluctuates due to fluctuations in the discharge pressure of the high pressure pump P2 or the opening of the electromagnetic control valve 18. It is. The sub fuel pressure Psub calculated in this way is stored in the RAM and read out during the fuel pressure control process as described above.

In step 72 following step 71, the air flow rate Gth is calculated by the following equation (11).
Gth = [Gth '(m) + Gth' (m-1) + …… + Gth '(m-w + 1)] / w (11)
Here, Gth ′ indicates a sampling value of the air flow rate sampled in synchronization with the generation of the CRK signal based on the detection signal of the throttle valve opening sensor 31.

  As shown in the above equation (11), the air flow rate Gth is calculated as a moving average value of the sampling value Gth ′. This is for appropriately calculating the air flow rate Gth while avoiding the influence even when the air flow rate fluctuates due to the intake pulsation.

  Next, at step 73, the intake air amount Gcyl is calculated for each cylinder 3a by the following equation (12).

  In this equation (12), Vb represents the intake pipe internal volume, and R represents a predetermined gas constant. In addition, the discrete data of the intake pipe absolute pressure PBA with the symbol (n) in the equation (12) indicates that the data is sampled in synchronization with the generation timing of the TDC signal, and the symbol n indicates the discrete data. It represents the order of sampling cycles. For example, PBA (n) indicates the current value of the intake pipe absolute pressure sampled at the current control timing, and PBA (n−1) indicates the value sampled at the previous control timing. . In the following description, the symbol (n) in each discrete data is omitted as appropriate.

Next, the routine proceeds to step 74, where the fuel amount Minj is calculated for each fuel injection valve 6 by the following equation (13).
Minj = Kgt / KCMD / KAF / Gcyl (13)

  In the above equation (13), Kgt is a conversion coefficient set in advance for each fuel injection valve 6. KCMD is a target air-fuel ratio (equivalent ratio converted value), and is calculated by a map search (not shown) according to the engine speed NE and the accelerator pedal opening AP. KAF is an air-fuel ratio correction coefficient, and is set to a value obtained by dividing the feedback correction coefficient KSTR by the target air-fuel ratio KCMD during execution of the air-fuel ratio feedback control, and is set to a value 1 while the air-fuel ratio feedback control is stopped. Is set. The feedback correction coefficient KSTR is set so that the detected air-fuel ratio KACT follows the target air-fuel ratio KCMD by a target value filter type two-degree-of-freedom sliding mode control algorithm (not shown) similar to the above-described equations (1) to (7). Calculated.

  In step 75 following step 74, the fuel pressure correction coefficient Kdp is searched by searching the table shown in FIG. 15 according to the deviation DPm (= Pmain−PBA) between the main fuel pressure Pmain and the intake pipe absolute pressure PBA. calculate. In this table, the fuel pressure correction coefficient Kdp is normalized so that Kdp = 1 when the deviation DPm is a predetermined value DPm1 (for example, Pmain = 10 MPa and PBA is atmospheric pressure). The deviation DPm is set to be smaller as the deviation DPm is larger.

  Next, the routine proceeds to step 76, where the basic fuel injection time Tcyl_base is calculated by searching the table shown in FIG. 16 according to the fuel amount Minj. In this table, the basic fuel injection time Tcyl_base is set to a larger value as the fuel amount Minj is larger. Further, in the region near Minj = 0, in order to compensate for the response delay when the fuel injection valve 6 is opened, the increase degree with respect to the increase in the fuel amount Minj is set to be larger than in other regions. ing.

  Next, the routine proceeds to step 77, where the invalid correction value TiVB is calculated by searching the table shown in FIG. 17 according to the battery voltage VB. As shown in the figure, the invalid correction value TiVB is set to a larger value as the battery voltage VB is lower. This is to compensate for the fact that the lower the battery voltage VB, the greater the delay until the fuel injection valve 6 actually opens during fuel injection.

Next, the process proceeds to step 78, and after calculating the fuel injection time Tcyl by the following equation (14), the present process is terminated.
Tcyl = Kdp · Tcyl_base + TiVB (14)

  Thus, the valve opening time and the valve opening timing of the fuel injection valve 6 are controlled according to the fuel injection time Tcyl calculated as described above. The final fuel injection time may be calculated by applying a predetermined adhesion correction process to the fuel injection time Tcyl calculated as described above.

  Next, the ignition timing control process described above will be described with reference to FIG. In this process, as described below, the ignition timing Iglog is calculated for each cylinder 3a, that is, for each spark plug 7. First, in step 90, it is determined whether or not the throttle valve failure flag F_THNG described above is “1”. If the determination result is NO and the throttle valve mechanism 5 is normal, the routine proceeds to step 91, where it is determined whether or not the engine start flag F_ENGSTART described above is “1”.

  If the decision result in the step 91 is YES and the engine start control is being performed, the process proceeds to a step 92, the ignition timing Iglog is set to a predetermined start time value Ig_crk (for example, BTDC 10 °), and this process is ended. .

  On the other hand, when the determination result of step 91 is NO and the engine start control is not being performed, the routine proceeds to step 93, where it is determined whether or not the accelerator opening AP is smaller than the predetermined value APREF described above. If the determination result is YES and the accelerator pedal is not depressed, the routine proceeds to step 94, where it is determined whether or not the catalyst warm-up control execution time Tcat is smaller than the predetermined value Tcatlmt described above.

  When the determination result is YES and Tcat <Tcatlmt, it is determined that the catalyst warm-up control should be executed, and the process proceeds to step 95 to calculate the catalyst warm-up value Ig_ast. Specifically, the catalyst warm-up value Ig_ast is calculated by a response designation control algorithm (sliding mode control algorithm or backstepping control algorithm) of the following equations (15) to (17).

  In the above equation (15), Ig_ast_base represents a predetermined catalyst warm-up reference ignition timing (for example, BTDC 5 °), and Krch_ig and Kadp_ig represent predetermined feedback gains. Further, σ_ig is a switching function defined as in Expression (16). In the equation (16), pole_ig is a response specifying parameter set so that the relationship of -1 <pole_ig <0 is established, and Enast is a tracking error calculated by the equation (17). In Expression (17), NE_ast is a predetermined target engine speed for warming up the catalyst (for example, 1800 rpm). By the control algorithm described above, the catalyst warm-up value Ig_ast is calculated as a value that converges the engine speed NE to the catalyst warm-up target speed NE_ast.

  Next, the routine proceeds to step 96, where the ignition timing Iglog is set to the catalyst warm-up value Ig_ast, and then this processing is terminated.

  On the other hand, when the determination result of step 93 or 94 is NO, that is, when the accelerator pedal is stepped on or when Tcat ≧ Tcatlmt, the routine proceeds to step 97, in accordance with the engine speed NE and the intake pipe absolute pressure PBA. The normal operation value Ig_map is calculated by searching the map shown in FIG.

  In the figure, PBA1 to PBA3 are predetermined values of the intake pipe absolute pressure PBA that satisfy the relationship of PBA1 <PBA2 <PBA3. As shown in the figure, in this map, the normal operation value Ig_map is set to a more retarded value in a region where the intake pipe absolute pressure PBA and the engine speed NE are high. This is to avoid the occurrence of knocking in a high load range.

  Next, the routine proceeds to step 98, where the ignition timing Iglog is set to the normal operation value Ig_map, and then this processing is terminated.

  On the other hand, if the determination result in step 90 is YES and the throttle valve mechanism 5 has failed, the process proceeds to step 99 to calculate a failure value Ig_fs. Specifically, the failure time value Ig_fs is calculated by a response designating control algorithm (sliding mode control algorithm or backstepping control algorithm) represented by the following equations (18) to (20).

In the above equation (18), Ig_fs_base represents a predetermined failure ignition reference ignition timing (for example, TDC ± 0 °), and Krch_ig ^# and Kadp_ig ^# represent predetermined feedback gains. Also, σ_ig ^# is a switching function defined as in equation (19). In the equation (19), pole_ig ^# is a response specifying parameter set so that the relationship of -1 <pole_ig ^# <0 is established, and Enfs is a tracking error calculated by the equation (20). In Expression (20), NE_fs is a predetermined failure target rotational speed (for example, 2000 rpm). By the above control algorithm, the failure value Ig_fs is calculated as a value for converging the engine speed NE to the failure target speed NE_fs.

  Next, the routine proceeds to step 100, where the ignition timing Iglog is set to the failure time value Ig_fs, and then this processing is terminated.

  Next, control results of the main fuel pressure Pmain and the sub fuel pressure Psub by the fuel pressure control apparatus 1 of the present embodiment configured as described above will be described. FIG. 20 shows an example of a control result by the fuel pressure control device 1 of this embodiment. FIG. 21 always holds the electromagnetic control valve 18 in a fully closed state for comparison, and only the main fuel pressure Pmain is used. The example of the control result at the time of controlling is shown. In addition, Mpump in both figures represents the discharge amount of the fuel of the high pressure pump P2.

  Referring to both figures, when the target main fuel pressure Pmain_cmd is set to a lower value and the pressure reduction control is started (time t1 and t11), the degree of decrease in the main fuel pressure Pmain after that is controlled according to the present embodiment. It can be seen that the result is larger than the comparative example. In the control result of the present embodiment, the main fuel pressure Pmain is reduced to the target main fuel pressure Pmain_cmd at the time tx, and the pressure reduction control is finished. On the other hand, the control result of the comparative example is the pressure increase control. It can be seen that the main fuel pressure Pmain has not been reduced to the target main fuel pressure Pmain_cmd even at the time when the operation is started (time t12). As described above, according to the fuel pressure control device 1 of the present embodiment, the electromagnetic control valve 18 is opened, and the fuel in the main fuel chamber 13a is caused to flow into the sub delivery pipe 17 side via the communication path 16. It can be seen that the main fuel pressure Pmain can be controlled to be reduced more quickly and effectively.

  Further, when the target main fuel pressure Pmain_cmd is set to a higher value and the pressure increase control is started, the degree of increase in the main fuel pressure Pmain during the pressure increase control (time t2 to t3 and t12 to t13) is also implemented in this embodiment. It can be seen that the control result of the embodiment is larger than that of the comparative example. In other words, the control result of the present embodiment has a shorter time required for pressure increase than the comparative example. This is because the main fuel pressure Pmain is increased while the sub fuel pressure Psub is used in addition to the high pressure pump P2 when the assist mode execution condition is satisfied and the electromagnetic control valve 18 is opened. It is. As described above, according to the fuel pressure control device 1 of the present embodiment, the initial responsiveness in the pressure increase control of the main fuel pressure Pmain can be improved, and the main fuel pressure Pmain can be increased more quickly and effectively. I understand.

  As described above, according to the fuel supply device 10 of the present embodiment, when the communication passage 16 is closed by the electromagnetic control valve 18, the fuel in the main fuel chamber 13a is increased by operating the high-pressure pump P2. Pressed. On the other hand, when the communication passage 16 is opened by the electromagnetic control valve 18, the fuel in the main fuel chamber 13a flows into the sub fuel chamber 17a, so that the main fuel chamber 13a is depressurized and the sub fuel pressure Psub is reduced. The low pressure relief valve 20 holds the set pressure Psub_max. As a result, the main fuel pressure Pmain can be reduced to the set pressure Psub_max, and by appropriately setting the set pressure Psub_max, it becomes possible to reduce the pressure to a lower value than before, and the increase / decrease is wider than before. It becomes possible to change the width.

  Further, according to the fuel pressure control device 1, in the fuel supply device 10 as described above, the main fuel pressure Pmain is controlled via the high-pressure pump P2 and the electromagnetic control valve 18, so that the main fuel pressure Pmain is conventionally increased. Can be quickly controlled to a lower value, and the main fuel pressure Pmain can be controlled with a wider control range than before. As a result, by controlling the gasoline engine 3 by the fuel pressure control device 1, the main fuel pressure Pmain supplied to the fuel injection valve 6 can be quickly reduced to an appropriate value during low load operation or the like. Thereby, good control accuracy in air-fuel ratio control can be ensured, and a stable operation state can be secured. For the same reason, it is possible to reduce the amount of fuel adhering to the inner wall of the cylinder by ensuring proper penetration in fuel spray, thereby reducing unburned HC and improving exhaust gas characteristics. In addition to this, by ensuring appropriate penetration in fuel spray, the air-fuel mixture can be formed in an appropriate state, and combustion efficiency can be improved.

  Further, when the mode is other than the decompression mode, the assist mode, and the filling mode (when the determination result of step 53 is NO), the electromagnetic control valve 18 is closed and the volume of the chamber for storing fuel is controlled to be smaller. As a result, the time required to increase the pressure of the fuel can be shortened, and the work of the high-pressure pump P2 can be reduced accordingly. As a result, the operating efficiency of the engine 3 can be improved.

  Further, until the catalyst warm-up control is finished (while Tcat <Tcatlmt is established), the electromagnetic control valve 18 is closed, and the volume of the chamber for storing fuel is controlled to a smaller value. The time required for the pressure increase of the fuel during the catalyst warm-up control can be shortened. As a result, fuel injection control can be executed with high accuracy during catalyst warm-up control, and combustion stability can be ensured, thereby reducing unburned HC and smoke (PM) emissions. Can do.

  Further, when the execution condition of the assist mode is satisfied (when the determination result of step 50 is YES), the electromagnetic control valve 18 is opened, so that the fuel in the auxiliary fuel chamber 17a is transferred to the main fuel chamber 13a. The main fuel pressure Pmain is increased. That is, since the main fuel pressure Pmain can be increased while using the sub fuel pressure Psub in addition to the high pressure pump P2, the initial responsiveness in the pressure increase control of the main fuel pressure Pmain can be improved. As a result, fuel injection control can be executed with higher accuracy, and better combustion stability can be ensured, thereby further reducing the amount of unburned HC and smoke (PM) emissions. it can.

  In the filling mode (when the determination result in step 52 is YES), that is, the absolute value | e | of the follow-up error is less than a predetermined value e_fup, and the main fuel pressure Pmain is sufficiently close to the target main fuel pressure Pmain_cmd. When the control is performed, the electromagnetic control valve 18 is opened and the fuel in the main fuel chamber 13a is filled into the sub fuel chamber 17a. Therefore, the control accuracy of the fuel injection control due to the shortage of the main fuel pressure Pmain is increased. While avoiding the decrease, the auxiliary fuel chamber 17a can be filled with the high-pressure fuel to increase the auxiliary fuel pressure Psub. Thereby, the pressure increase control in the assist mode described above can be executed.

  In general, when fuel pressure control is executed using a fuel pump such as the high-pressure pump P2 and the electromagnetic control valve 18, the fuel pressure overshoots its target value due to the low response. As a result, the work of the fuel pump increases more than necessary. On the other hand, in the fuel pressure control device 1 of the present embodiment, the high pressure pump P2 and the electromagnetic are controlled so that the main fuel pressure Pmain follows the target main fuel pressure Pmain_cmd by the target value filter type two-degree-of-freedom sliding mode control algorithm. Since the control valve 18 is controlled, an overshoot of the main fuel pressure Pmain with respect to the target main fuel pressure Pmain_cmd can be avoided, and the followability of the main fuel pressure Pmain to the target main fuel pressure Pmain_cmd can be improved. As a result, the work of the high-pressure pump P2 can be reduced, and the fuel consumption of the engine 3 can be improved.

  Further, in the fuel pressure control device 1 as in this embodiment, when the electromagnetic control valve 18 is opened during the operation of the high pressure pump P2, the sub fuel pressure Psub applied to the main fuel chamber 13a is equal to the main fuel pressure Pmain. Although it may act as a disturbance in the control and the main fuel pressure Pmain may be in a vibrating state, as described above, by controlling the main fuel pressure Pmain by the target value filter type two-degree-of-freedom sliding mode control algorithm, The main fuel pressure Pmain can be made to follow the target main fuel pressure Pmain_cmd while avoiding the main fuel pressure Pmain from oscillating due to the disturbance effect of the fuel pressure Psub. As a result, the control accuracy of the fuel injection control can be improved.

  The first embodiment is an example in which Usol = 1 is set in the assist mode, the filling mode, and the decompression mode, and the electromagnetic control valve 18 is controlled to be fully opened. In these modes, the electromagnetic control is performed. You may comprise so that the valve | bulb 18 may be controlled to the intermediate opening degree of a fully closed state and a fully open state.

  Next, the fuel supply device 10A and the fuel pressure control device 1A according to the second embodiment will be described. As shown in FIG. 22, this fuel supply device 10A is configured in the same manner as the fuel supply device 10 (see FIG. 3) of the first embodiment except for a part thereof. About the same structure as the supply apparatus 10, while attaching | subjecting the same code | symbol, the description is abbreviate | omitted and only a different point is demonstrated.

  As is clear from a comparison of FIGS. 22 and 3, the fuel supply apparatus 10 </ b> A has a configuration in which the auxiliary delivery pipe 17 and the low-pressure relief valve 20 are omitted from the fuel supply apparatus 10 of the first embodiment. Therefore, in the fuel pressure control device 1A of the second embodiment, the auxiliary fuel pressure sensor 38 that detects the auxiliary fuel pressure Psub in the auxiliary delivery pipe 17 in the fuel pressure control device 1 of the first embodiment is omitted.

  Further, the fuel pressure control process by the fuel pressure control device 1A is different from the fuel pressure control process of FIG. 9 by the fuel pressure control device 1 of the first embodiment only in the content of the calculation process of the valve control input Usol in step 35. Other than that, the configuration is the same. In the fuel pressure control apparatus 1A, the calculation process of the valve control input Usol is executed as shown in FIG.

  First, in step 110, it is determined whether or not the control input Usl is smaller than 0. This condition represents the execution condition of the decompression mode in which the main fuel pressure Pmain is reduced by letting the main fuel pressure Pmain escape to the fuel tank 11 side. In this case, Usl <0 is satisfied because σ> 0 For example, in the case of pressure reduction control in which the target main fuel pressure Pmain_cmd is set to a value lower than the main fuel pressure Pmain, Pmain> Pmain_cmd_f is satisfied.

  If the determination result in step 110 is YES and the execution condition of the pressure reduction mode is satisfied, the process proceeds to step 111, the valve control input Usol is set to -Usl, and the process is terminated. Thereby, the opening degree of the electromagnetic control valve 18 is controlled to a value corresponding to the value -Usl, and the pressure reduction control of the main fuel pressure Pmain is executed.

  On the other hand, if the determination result in step 110 is NO and the execution condition of the pressure reduction mode is not satisfied, the process proceeds to step 112, the valve control input Usol is set to 0, and the process is terminated. As a result, the electromagnetic control valve 18 is held in the closed state.

  Next, the control result of the main fuel pressure Pmain by the fuel pressure control device 1A of the second embodiment configured as described above will be described. FIG. 24 shows a control result example by the fuel pressure control apparatus 1A of the second embodiment. With reference to FIG. 21 and FIG. 21 described above, when the target main fuel pressure Pmain_cmd is set to a lower value and the pressure reduction control is started (time t21 and t11), the main fuel pressure Pmain decreases thereafter. It can be seen that the degree is greater in the control result of the second embodiment than in the comparative example.

  Further, in the control result of the second embodiment, at time ty, the main fuel pressure Pmain is reduced to the target main fuel pressure Pmain_cmd and the pressure reduction control is finished, whereas in the control result of the comparative example, the pressure increase It can be seen that the main fuel pressure Pmain is not reduced to the target main fuel pressure Pmain_cmd even at the time when the control is started (time t12). As described above, according to the fuel pressure control device 1A of the second embodiment, similarly to the fuel pressure control device 1 of the first embodiment, the electromagnetic control valve 18 is opened and the fuel in the main fuel chamber 13a is fueled. It can be seen that the main fuel pressure Pmain can be reduced more quickly and effectively by returning to the fuel tank 11 side via the return path 19.

  Further, when the target main fuel pressure Pmain_cmd is set to a higher value and the pressure increase control is started, the increase degree of the main fuel pressure Pmain during the pressure increase control (time t22 to t23 and t12 to t13) It can be seen that both the embodiment and the comparative example have the same level.

  FIG. 25 is a comparison of the control result of the fuel pressure control by the fuel pressure control apparatus 1A of the second embodiment and the control result of the fuel pressure control by the fuel pressure control apparatus 1 of the first embodiment at the same timing. It is. As shown in the figure, when the pressure increase control is started (time t31), the degree of increase in the main fuel pressure Pmain after that is equal to the first embodiment using the sub fuel pressure Psub. It is larger than that of the second embodiment. That is, as in the first embodiment, by using the auxiliary fuel pressure Psub, the initial responsiveness in the pressure increase control of the main fuel pressure Pmain can be improved, and the corresponding increase in the main fuel pressure Pmain is required. It turns out that time can be shortened.

  On the other hand, when the pressure reduction control is started (time t32), the degree of decrease in the main fuel pressure Pmain after that is almost the same at the initial stage, and the fuel return path in the second embodiment is the same. It can be seen that when 19 is in an open state, the pressure can be reduced to a lower value.

  As described above, according to the fuel pressure control device 1A of the second embodiment, as with the fuel pressure control device 1 of the first embodiment, the main fuel pressure Pmain can be controlled to be reduced more quickly and effectively. The fuel pressure can be controlled with a wider control range than before. As a result, similar to the fuel pressure control device 1 of the first embodiment, good control accuracy in air-fuel ratio control can be ensured during low load operation, and a stable operation state can be ensured. For the same reason, it is possible to reduce the amount of fuel adhering to the inner wall of the cylinder by ensuring proper penetration in fuel spray, thereby reducing unburned HC and improving exhaust gas characteristics. In addition to this, by ensuring appropriate penetration in fuel spray, the air-fuel mixture can be formed in an appropriate state, and combustion efficiency can be improved.

  In addition, as with the fuel pressure control device 1 of the first embodiment, the high pressure pump is configured so that the main fuel pressure Pmain follows the target main fuel pressure Pmain_cmd by the target value filter type two-degree-of-freedom sliding mode control algorithm. Since P2 and the electromagnetic control valve 18 are controlled, the above-described operational effects can be obtained.

  Each embodiment is an example in which the fuel supply device and the fuel pressure control device of the present invention are applied to an internal combustion engine using gasoline as fuel, but the fuel supply device and the fuel pressure control device of the present invention are not limited thereto. It is applicable to an internal combustion engine such as a diesel engine in which fuel is directly injected into a cylinder by a fuel injection valve.

  In addition, each embodiment is an example using the electromagnetic control valve 18 as a control valve, but the control valve is not limited to this, and any control valve may be used as long as it can be electrically controlled. For example, an electric motor type electric valve may be used.

1 is a diagram schematically showing a schematic configuration of an internal combustion engine to which a fuel supply device and a fuel pressure control device according to a first embodiment of the present invention are applied. It is a block diagram which shows schematic structure of a fuel pressure control apparatus. It is a figure which shows typically schematic structure of a fuel supply apparatus. It is a flowchart which shows the control processing performed with predetermined period (DELTA) Tk. It is a flowchart which shows an intake air amount control process. It is a figure which shows an example of the table used for calculation of target opening TH_cmd during engine starting control. It is a figure which shows an example of the map used for calculation of target opening TH_cmd during catalyst warm-up control. It is a figure which shows an example of the map used for calculation of target opening TH_cmd during normal driving | operation. It is a flowchart which shows a fuel pressure control process. It is a flowchart which shows the calculation process of the pump control input Upump. It is a figure which shows an example of the map used for calculation of the value for normal driving | operation Pmain_map. It is a flowchart which shows the calculation process of valve control input Usol. It is a flowchart which shows the control processing performed synchronizing with the generation | occurrence | production timing of a TDC signal. It is a flowchart which shows a fuel-injection control process. It is a figure which shows an example of the table used for calculation of the fuel pressure correction coefficient Kdp. It is a figure which shows an example of the table used for calculation of basic fuel injection time Tcyl_base. It is a figure which shows an example of the table used for calculation of invalid correction value TiVB. It is a flowchart which shows an ignition timing control process. It is a figure which shows an example of the map used for calculation of normal operation value Ig_map. It is a timing chart which shows the example of a control result of fuel pressure by the fuel pressure control device of a 1st embodiment. It is a timing chart which shows the control result of the fuel pressure of a comparative example. It is a figure which shows typically schematic structure of the fuel supply apparatus which concerns on 2nd Embodiment. It is a flowchart which shows the calculation process of the valve control input Usol in the fuel pressure control process of 2nd Embodiment. It is a timing chart which shows the example of a control result of fuel pressure by the fuel pressure control device of a 2nd embodiment. It is a timing chart for comparing the control result of the fuel pressure by the fuel pressure control device of the first and second embodiments.

Explanation of symbols

1, 1A Fuel pressure control device 2 ECU (pump control means, pressure reduction condition judgment means, valve control means, pressure increase condition judgment means, target main fuel pressure setting means, control means, target fuel pressure setting means)
DESCRIPTION OF SYMBOLS 3 Internal combustion engine 3a Cylinder 6 Fuel injection valve 10 Fuel supply apparatus 11 Fuel tank (fuel storage chamber)
12 Fuel supply path 13a Main fuel chamber (fuel chamber)
16 Communication path (fuel return path)
17a Sub fuel chamber (fuel return path)
18 Electromagnetic control valve (control valve)
19 Fuel return path 20 Low pressure relief valve (relief valve)
P2 High pressure pump (fuel pump)
37 Main fuel pressure sensor (main fuel pressure detection means, fuel pressure detection means)
38 Sub fuel pressure sensor (Sub fuel pressure detecting means)
Pmain Main fuel pressure (fuel pressure)
Pmain_cmd Target main fuel pressure (target fuel pressure)
Psub Sub fuel pressure Psub_max Predetermined set pressure Tcatlmt Predetermined value (predetermined time)
e Tracking error (deviation)
e_fup predetermined value

Claims (10)

In a cylinder injection internal combustion engine in which fuel is injected into a cylinder by a fuel injection valve, the fuel supply device for the internal combustion engine supplies fuel to the fuel injection valve,
A fuel storage chamber for storing fuel;
A fuel supply path extending between the fuel storage chamber and the fuel injection valve;
A fuel pump provided in the fuel supply path for increasing the pressure of the fuel and supplying the fuel to the fuel injection valve;
A main fuel chamber, which is provided between the fuel pump and the fuel injection valve of the fuel supply path, and stores fuel increased in pressure by the fuel pump;
A sub fuel chamber that communicates with the main fuel chamber via a communication path, and stores fuel from the main fuel chamber;
A control valve for controlling the opening and closing of the communication path;
A fuel return path extending between the auxiliary fuel chamber and the fuel storage chamber;
A relief valve that opens the fuel return path by opening when the fuel pressure in the auxiliary fuel chamber exceeds a predetermined set pressure;
A fuel supply device for an internal combustion engine, comprising: A fuel pressure control device for an internal combustion engine having the fuel supply device according to claim 1,
Main fuel pressure detecting means for detecting a main fuel pressure which is a fuel pressure in the main fuel chamber;
Pump control means for controlling the fuel pump according to the detected main fuel pressure;
Pressure reducing condition determining means for determining whether a pressure reducing condition for reducing the main fuel pressure is satisfied according to the detected main fuel pressure;
Based on the determination result of the pressure reducing condition determining means, the control valve is opened when the pressure reducing condition is satisfied, and is closed when the pressure reducing condition is not satisfied, and
A fuel pressure control apparatus for an internal combustion engine, comprising:   3. The valve control unit according to claim 2, wherein the valve control unit closes the control valve until a predetermined time elapses after the start of the internal combustion engine, regardless of a determination result of the decompression condition determination unit. A fuel pressure control device for an internal combustion engine as described. Sub fuel pressure detecting means for detecting a sub fuel pressure which is a fuel pressure in the sub fuel chamber;
A pressure increasing condition determining means for determining whether a pressure increasing condition for increasing the main fuel pressure is satisfied according to the main fuel pressure;
Further comprising
The valve control means opens the control valve when the main fuel pressure is lower than the sub fuel pressure when the pressure increasing condition is satisfied based on the determination result of the pressure increasing condition determining means. The fuel pressure control device for an internal combustion engine according to claim 2 or 3, Further comprising target main fuel pressure setting means for setting a target main fuel pressure as a target of the main fuel pressure according to the operating state of the internal combustion engine;
The valve control means opens the control valve when the absolute value of the deviation between the main fuel pressure and the target main fuel pressure is less than a predetermined value regardless of the determination result of the pressure reducing condition determination means. The fuel pressure control device for an internal combustion engine according to any one of claims 2 to 4. A fuel pressure control device for an internal combustion engine having the fuel supply device according to claim 1,
Main fuel pressure detecting means for detecting a main fuel pressure which is a fuel pressure in the main fuel chamber;
Target main fuel pressure setting means for setting a target main fuel pressure as a target of the main fuel pressure according to the operating state of the internal combustion engine;
Control means for controlling the fuel pump and the control valve so that the main fuel pressure follows the target main fuel pressure by a control algorithm including a predetermined two-degree-of-freedom control algorithm;
A fuel pressure control apparatus for an internal combustion engine, comprising: A fuel pressure control device for an internal combustion engine having the fuel supply device according to claim 1,
Main fuel pressure detecting means for detecting a main fuel pressure which is a fuel pressure in the main fuel chamber;
Target main fuel pressure setting means for setting a target main fuel pressure as a target of the main fuel pressure according to the operating state of the internal combustion engine;
Control means for controlling the fuel pump and the control valve so that the main fuel pressure follows the target main fuel pressure by a control algorithm including a predetermined response designating control algorithm;
A fuel pressure control apparatus for an internal combustion engine, comprising: In-cylinder injection internal combustion engine in which fuel stored in a pressurized state in a fuel chamber is injected into a cylinder via a fuel injection valve, and has a fuel return path for returning the fuel in the fuel chamber to the fuel storage chamber In the engine, a fuel pressure control device for an internal combustion engine for controlling a fuel pressure in the fuel chamber,
A fuel pump for increasing the pressure of the fuel in the fuel storage chamber and supplying the fuel to the fuel chamber;
A control valve for opening and closing the fuel return path;
Fuel pressure detecting means for detecting the fuel pressure in the fuel chamber;
Control means for controlling the fuel pump and the control valve according to the detected fuel pressure;
A fuel pressure control apparatus for an internal combustion engine, comprising: Further comprising target fuel pressure setting means for setting a target fuel pressure as a target of the fuel pressure in accordance with the operating state of the internal combustion engine;
The control means controls the fuel pump and the control valve so that the fuel pressure follows the target fuel pressure by a control algorithm including a predetermined two-degree-of-freedom control algorithm. A fuel pressure control device for an internal combustion engine according to claim 1. Further comprising target fuel pressure setting means for setting a target fuel pressure as a target of the fuel pressure in accordance with the operating state of the internal combustion engine;
The control means controls the fuel pump and the control valve so that the fuel pressure follows the target fuel pressure by a control algorithm including a predetermined response assignment control algorithm. A fuel pressure control device for an internal combustion engine according to claim 1.

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