Control device for internal combustion engine

Abstract

The invention provides a control device for an internal combustion engine, which can simultaneously improve the stability and responsiveness of the transient response of the discharge pressure of a high-pressure fuel pump to a pressure target value. A control device (ECU 100) for an internal combustion engine is provided with a feedback control unit (110), a flow rate restriction unit (120), and an energization start angle calculation unit (130). A feedback control unit (110) outputs, as inputs, a pressure detection value (Pd) of a pressure sensor for fuel discharged from a high-pressure fuel pump to a fuel injection device and a pressure target value (Pt) of the discharge pressure of the high-pressure fuel pump, a pressure deviation ([delta] P) between the pressure detection value (Pd) and the pressure target value (Pt), and a flow rate target value (QT) of the discharge flow rate of the high-pressure fuel pump. A flow rate limiting unit (120) outputs a limited flow rate value (QL) in which the flow rate target value (QT) is limited, on the basis of the value of the pressure deviation ([delta] P) and the amount of change, using the pressure deviation ([delta] P) and the flow rate target value (QT) as inputs. An energization start angle calculation unit (130) calculates an energization start phase ([theta] on) during the reciprocating motion of the plunger on the basis of the limited flow rate value (QL), and starts energization of the solenoid valve of the high-pressure fuel pump at the energization start phase ([theta] on).

Description

Technical Field

[0001] The present invention relates to a control device for an internal combustion engine. Background Art

[0002] The control device of the internal combustion engine is well known in the past. For example, the control device of the internal combustion engine described in the following patent document 1 controls the internal combustion engine, which includes an internal combustion engine driven high-pressure fuel pump (paragraph 0014, claim 1) that supplies high-pressure fuel from a fuel tank to a fuel injection unit. The high-pressure fuel pump is driven by a cam of the internal combustion engine. By closing the opening and closing valve on the inlet side of the high-pressure fuel pump at a desired time based on the angle of the shaft driving the cam, a desired discharge amount of high-pressure fuel is discharged.

[0003] This conventional control device includes: a unit for detecting the rotation speed of the internal combustion engine; a unit for detecting the pressure of the high-pressure fuel; and a control unit for performing feedback control on the high-pressure fuel pump so that the detected pressure of the high-pressure fuel becomes a target pressure. The control unit includes: a unit for calculating the deviation between the detected pressure of the high-pressure fuel and the target pressure; a unit for calculating the feedback operation amount based on the deviation; and a calculation unit for calculating the required discharge amount of the high-pressure fuel pump based on the feedback operation amount.

[0004] Furthermore, the control unit includes: a unit for calculating the shaft angle that satisfies the required discharge volume in consideration of the rotation speed of the internal combustion engine and the detected pressure of the high-pressure fuel; and a unit for controlling the switch valve to close when the calculated shaft angle is reached. The control device also includes: a unit for detecting a sudden change in the target pressure; and a unit for maintaining the parameters of the feedback control unchanged when the sudden change is detected.

[0005] The conventional control device for the internal combustion engine maintains the integral term as a parameter of the feedback control without updating it when the target pressure of the high-pressure fuel changes suddenly. This can avoid the integral term being greatly integrated and calculating a large integral term when the deviation is large, and can avoid large overshoot or large undershoot (Patent Document 1, paragraph 0015). Prior art literature Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2007-032322 Summary of the invention Problem that the invention aims to solve

[0007] In the above-mentioned conventional control device for an internal combustion engine, by maintaining the integral term of the feedback control without updating, it is possible to prevent the discharge pressure of the high-pressure fuel pump from greatly exceeding the pressure target value, thereby improving the stability of the transient response. However, in the conventional control device for an internal combustion engine, the responsiveness of the discharge pressure of the high-pressure fuel pump to the pressure target value may decrease.

[0008] The present invention provides a control device for an internal combustion engine, which can simultaneously improve the stability and responsiveness of the transient response of the discharge pressure of a high-pressure fuel pump to a pressure target value. Technical means of solving problems

[0009] One aspect of the present invention is a control device for an internal combustion engine, which controls the discharge pressure of fuel discharged from a high-pressure fuel pump to a fuel injection device, the high-pressure fuel pump comprising: a pressurizing chamber, into which the fuel is introduced from a fuel tank via a low-pressure fuel pump; a solenoid valve, which opens and closes a flow path for introducing the fuel into the pressurizing chamber; and a plunger, which pressurizes the fuel introduced into the pressurizing chamber, the fuel injection device injects the fuel into a combustion chamber of the internal combustion engine, and the control device for the internal combustion engine is characterized in that it comprises: a feedback control unit, which controls the pressure of the fuel discharged from the high-pressure fuel pump to the fuel injection device A sensor pressure detection value and a pressure target value of the discharge pressure are used as inputs, and a pressure deviation between the pressure detection value and the pressure target value and a flow target value of the discharge flow of the high-pressure fuel pump are output; a flow limiting unit, which takes the pressure deviation and the flow target value as inputs, and outputs a restricted flow value obtained by limiting the flow target value based on the value and change of the pressure deviation; and an energization start angle calculation unit, which calculates the energization start phase in the reciprocating motion of the plunger based on the restricted flow value, and starts energizing the solenoid valve of the high-pressure fuel pump at this energization start phase. Effects of the Invention

[0010] According to the above aspect of the present invention, it is possible to provide a control device for an internal combustion engine capable of improving both the stability and the responsiveness of a transient response of the delivery pressure of a high-pressure fuel pump to a pressure target value. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a block diagram of one embodiment of the control device for an internal combustion engine according to the present invention. Figure 2 Yes means Figure 1 A block diagram of a configuration example of a control device for an internal combustion engine. Figure 3 Yes means Figure 2 A block diagram of an example of a flow rate limiting unit of a control device for an internal combustion engine. Figure 4 Yes means Figure 3 Flow chart of the processing flow of the flow limiting unit. Figure 5 Yes, it indicates confirmation Figure 4 A limit value map is an example of a limit value processing. Figure 6 Yes Description Figure 2 A diagram showing the effect of a control device of an internal combustion engine is shown. Figure 7 Yes means Figure 3 A block diagram of a modified example of a flow rate limiting unit. Figure 8 yes Figure 2 A block diagram of an example of an FDBK control unit of a control device for an internal combustion engine. DETAILED DESCRIPTION

[0012] Hereinafter, embodiments of a control device for an internal combustion engine according to the present invention will be described with reference to the drawings.

[0013] Figure 1 1 is a block diagram showing an embodiment of a control device for an internal combustion engine of the present invention. The control device for an internal combustion engine of the present embodiment is constituted by, for example, an electronic control unit (ECU) 100 which is a part of an engine system 1 mounted on a vehicle. The engine system 1 includes, for example, an engine 2 which is an internal combustion engine, a fuel tank 3, a low-pressure fuel pump 4, a high-pressure fuel pump 5, a fuel injection device 6, an accelerator opening sensor 7, and the ECU 100.

[0014] The engine 2 includes, for example, an intake pipe, a throttle body, a throttle valve, an intake manifold, an intake port, a cylinder, a spark plug, a piston, a crankshaft, a camshaft, an exhaust port, and an exhaust pipe, which are not shown in the figure. The engine 2, for example, takes in intake air into the intake pipe according to the movement of the piston. When the intake air sucked into the intake pipe passes through the throttle body, its flow rate is controlled by a throttle valve provided on the throttle body.

[0015] The air sucked in through the throttle body passes through the intake manifold, and then mixes with the fuel injected from the injector 62 provided at the intake port, and is introduced into the combustion chamber of the cylinder in the form of a mixed gas. The spark plug causes the mixed gas in the combustion chamber to explosively burn through spark ignition to generate mechanical energy, and rotates the crankshaft and camshaft connected to the piston. The gas generated by the combustion is discharged from the combustion chamber of the cylinder through the exhaust port to the exhaust pipe, and is discharged from the exhaust pipe to the outside of the vehicle as exhaust gas.

[0016] The fuel tank 3 stores liquid fuel such as gasoline, light oil, ethanol, etc. The low-pressure fuel pump 4 is provided, for example, in the middle of a fuel supply pipe 8 connecting the fuel tank 3 and the high-pressure fuel pump 5, and pressure-feeds fuel from the fuel tank 3 to the high-pressure fuel pump 5 through the fuel supply pipe 8. The high-pressure fuel pump 5 pressurizes the fuel supplied through the fuel supply pipe 8 and discharges it to the common rail 61 of the fuel injection device 6.

[0017] In addition, the discharge pressure of the fuel of the low-pressure fuel pump 4 is lower than the discharge pressure of the fuel of the high-pressure fuel pump 5, and the discharge pressure of the fuel of the high-pressure fuel pump 5 is higher than the discharge pressure of the fuel of the low-pressure fuel pump 4. That is, the "low pressure" and "high pressure" in the low-pressure fuel pump 4 and the high-pressure fuel pump 5 represent the relative relationship between the discharge pressures of the respective fuel pumps, and do not define a specific pressure range.

[0018] The high-pressure fuel pump 5 includes, for example, a suction port 51, a solenoid valve 52, a pressurizing chamber 53, a plunger 54, a discharge valve 55, and a discharge port 56. The suction port 51 is connected to, for example, a fuel supply pipe 8, and introduces the fuel pressure-sent by the low-pressure fuel pump 4. The solenoid valve 52 is, for example, provided in the middle of a flow path 57 that supplies fuel from the suction port 51 to the pressurizing chamber 53, and is controlled to open and close by the ECU 100, so as to open and close the flow path 57 that supplies fuel to the pressurizing chamber 53.

[0019] The fuel is introduced from the fuel tank 3 to the pressurizing chamber 53 via the low-pressure fuel pump 4. More specifically, the fuel is introduced from the fuel tank 3 to the suction port 51 via the low-pressure fuel pump 4, and then introduced to the pressurizing chamber 53 through the flow path 57 between the suction port 51 and the pressurizing chamber 53 and the solenoid valve 52 that opens and closes the flow path 57. The high-pressure fuel pump 5 may also include a pulsation reducing unit 58 for reducing the pulsation of the pressure of the fuel sucked from the suction port 51 and discharged from the discharge port 56.

[0020] The plunger 54 pressurizes the fuel introduced into the pressurizing chamber 53. The plunger 54 is housed in, for example, a cylinder 59, and defines the pressurizing chamber 53 together with the cylinder 59. The plunger 54 is arranged to be reciprocable in the axial direction by a driving mechanism (not shown). The driving mechanism, for example, causes the plunger 54 to reciprocate in the axial direction by the rotation of a cam mounted on a camshaft of the engine 2.

[0021] The phase of the reciprocating motion of the plunger 54 is detected by, for example, a cam angle sensor that detects the rotation angle of the camshaft, and is input to the ECU 100. That is, the cam angle sensor functions as, for example, an angle sensor that detects the phase of the plunger 54 of the high-pressure fuel pump 5, and the phase detection value θd of the reciprocating motion of the plunger 54 can be calculated based on the cam angle λcam detected by the cam angle sensor.

[0022] The discharge valve 55 is provided between the pressurizing chamber 53 and the discharge port 56. In a state where there is no pressure difference between the fuel inside the pressurizing chamber 53 and the fuel on the downstream side of the discharge valve 55, the discharge valve 55 is in a closed state by causing the valve body to contact the seat surface of the valve seat member by the force of the spring. If the pressure of the fuel inside the pressurizing chamber 53 becomes greater than the pressure of the fuel on the downstream side of the discharge valve 55 and the pressure difference exceeds the force of the spring, the valve body leaves the seat surface of the valve seat member and becomes an open state. The discharge port 56 is connected to the common rail 61 of the fuel injection device 6, for example, and discharges the high-pressure fuel pressurized by the pressurizing chamber 53 to the common rail 61.

[0023] The fuel injection device 6 includes, for example, a common rail 61, an injector 62, and a pressure sensor 63. The common rail 61 stores the high-pressure fuel supplied from the high-pressure fuel pump 5, and distributes the high-pressure fuel to a plurality of injectors 62. Each injector 62, for example, injects the high-pressure fuel supplied via the common rail 61 into a cylinder of the engine 2. The pressure sensor 63 detects the pressure of the high-pressure fuel discharged from the high-pressure fuel pump 5 to the common rail 61, and outputs the pressure detection result to the ECU 100 via a signal line.

[0024] The accelerator opening sensor 7 is connected to the ECU 100, for example, via a signal line, detects the amount of depression of the accelerator pedal by the driver of the vehicle as the accelerator opening, and outputs the detected accelerator opening to the ECU 100. The ECU 100 is composed of, for example, one or more microcontrollers, and is connected to the low-pressure fuel pump 4, the high-pressure fuel pump 5, and the fuel injection device 6 via a signal line to control these low-pressure fuel pump 4, the high-pressure fuel pump 5, and the fuel injection device 6.

[0025] Figure 2 Yes means Figure 1 The block diagram of the configuration example of the ECU 100 is shown in FIG. The ECU 100, which is the control device of the internal combustion engine of the present embodiment, controls the discharge pressure of the fuel discharged from the high-pressure fuel pump 5 to the fuel injection device 6, and the fuel injection device 6 injects the fuel into the combustion chamber of the engine 2. The ECU 100 includes, for example, a feedback (FDBK) control unit 110, a flow rate limiting unit 120, and an energization start angle calculation unit 130. In addition, the ECU 100 includes, for example, an energization start angle limiting unit 140, an energization end angle calculation unit 150, an energization end angle limiting unit 160, and a solenoid valve control unit 170.

[0026] Figure 2 Each part of the ECU 100 shown in the figure represents each function of the control device of the internal combustion engine of the present embodiment which is realized by executing a program stored in a storage device such as a memory by a central processing unit (CPU). Figure 2 Each part of the ECU 100 shown may be constituted by, for example, one or more devices as one part, or may be constituted by one device as a plurality of parts.

[0027] The feedback control unit 110 receives as input, for example, a pressure detection value Pd of the pressure sensor 63 of the fuel discharged from the high-pressure fuel pump 5 to the fuel injection device 6, and a pressure target value Pt of the discharge pressure of the high-pressure fuel pump 5. The ECU 100 receives as input, for example, the pressure target value Pt of the discharge pressure of the high-pressure fuel pump 5 calculated based on the detection value of the accelerator opening sensor 7.

[0028] The feedback control unit 110 outputs, for example, a pressure deviation ΔP between the pressure detection value Pd and the pressure target value Pt, and a flow rate target value QT of the discharge flow rate of the high-pressure fuel pump 5 based on the input pressure detection value Pd and the pressure target value Pt. More specifically, the feedback control unit 110 calculates the flow rate target value QT as the required discharge flow rate of the high-pressure fuel pump 5 required to make the pressure detection value Pd and the pressure target value Pt coincide with each other.

[0029] Figure 3 Yes means Figure 2 1 is a block diagram of an example of a flow rate limiting unit 120 of the ECU 100. The flow rate limiting unit 120 receives the pressure deviation ΔP and the flow rate target value QT as inputs, and outputs a limited flow rate value QL that limits the flow rate target value QT according to the value of the pressure deviation ΔP and the change amount dΔP. The flow rate limiting unit 120 includes, for example, a change amount calculation unit 121, a limit value determination unit 122, a limited flow rate value calculation unit 123, and a limit processing unit 124.

[0030] Figure 4 Yes means Figure 3 Flow chart of the processing flow of the energization start angle calculation unit 130. Figure 4 In the process flow shown, the flow rate limiting unit 120 first starts a process S1 of calculating the change amount dΔP of the pressure deviation ΔP. In this process S1, the change amount calculating unit 121 calculates the change amount dΔP of the pressure deviation ΔP based on the pressure deviation ΔP input from the feedback control unit 110, for example.

[0031] Here, the change amount dΔP of the pressure deviation ΔP refers to the increase or decrease of the pressure deviation ΔP per unit time, that is, the change rate of the pressure deviation ΔP. More specifically, the change amount calculation unit 121 calculates the change amount dΔP of the pressure deviation ΔP by, for example, dividing the difference between the pressure deviation ΔP obtained in the previous process and the pressure deviation ΔP obtained in the current process by the process cycle.

[0032] Next, the flow rate limiting unit 120 performs a process S2 for determining the limit value LV. In the process S2, the limit value determining unit 122 determines a larger limit value LV as the value of the pressure deviation ΔP decreases and the amount of change dΔP of the pressure deviation ΔP increases. More specifically, the limit value determining unit 122 determines the limit value LV based on the value of the pressure deviation ΔP and the amount of change dΔP thereof, for example, using a limit value map stored in a storage device such as a memory constituting the ECU 100.

[0033] Figure 5 It means to confirm Figure 4 This is a diagram showing an example of a limit value map used in the process S2 of the limit value LV. Figure 5 In the figure, the limit value LV(H) represented by the dark circle is a limit value LV greater than the limit value LV(L) represented by the light circle. The limit value map is, for example, a graph with the horizontal axis representing the pressure deviation ΔP [%] and the vertical axis representing the change dΔP [% / sec], and it is stipulated that as the value of the pressure deviation ΔP decreases and the change dΔP of the pressure deviation ΔP increases, a larger limit value LV(H) is selected.

[0034] exist Figure 5 In the example shown, two limit values ​​LV of different sizes, namely a relatively large limit value LV (H) and a small limit value LV (L), are specified, but three or more limit values ​​LV of different sizes may also be specified. Figure 5 In the example shown, the limit value LV is not set until the pressure detection value Pd reaches 63.2% of the pressure target value Pt, that is, until the pressure deviation ΔP between the pressure target value Pt and the pressure detection value Pd is 36.8[%] or less. The limit value determination unit 122 refers to such a limit value map and determines the limit value LV based on the value of the pressure deviation ΔP and the change amount dΔP of the pressure deviation ΔP.

[0035] Next, the flow rate limiting unit 120 performs a process S3 of calculating the limit flow rate value QL. In the process S3, the limit flow rate value calculation unit 123 calculates the limit flow rate value QL by subtracting the limit value LV from the upper limit discharge flow rate Qmax based on the static characteristics of the high pressure fuel pump 5, for example. The upper limit discharge flow rate Qmax based on the static characteristics of the high pressure fuel pump 5 is, for example, Figure 2 As shown, the current is input from the energization start angle calculation unit 130 to the flow rate restriction unit 120 .

[0036] Next, the flow rate limiting unit 120 performs a flow rate limiting process S4 for limiting the flow rate target value QT using the limited flow rate value QL. Figure 3As shown, in this process S4, the restriction processing unit 124 receives as input the restricted flow rate value QL output from the restricted flow rate value calculation unit 123 and the flow rate target value QT output from the feedback control unit 110. For example, the restriction processing unit 124 outputs the flow rate target value QT when the flow rate target value QT does not exceed the restricted flow rate value QL, and outputs the restricted flow rate value QL when the flow rate target value QT exceeds the restricted flow rate value QL.

[0037] Thus, the output of the flow rate limiting unit 120 is limited to a limit flow rate value QL or less, which is obtained by subtracting the limit value LV from the upper limit discharge flow rate Qmax. Figure 4 The processing flow of the flow rate limiting unit 120 shown ends.

[0038] The energization start angle calculation unit 130 is, for example, Figure 2 As shown, the rotation speed Re of the engine 2 and the voltage Vb of the battery, as well as the limit flow value QL or the flow target value QT outputted from the flow limiter 120 are inputted. The energization start angle calculation unit 130 calculates the energization start phase θon of the reciprocating motion of the plunger 54 based on the input limit flow value QL or the flow target value QT, and starts energizing the solenoid valve 52 of the high-pressure fuel pump 5 at the energization start phase θon.

[0039] In addition, the energization start angle calculation unit 130 refers to, for example, a static characteristic map of the high-pressure fuel pump 5 stored in a storage device such as a memory of the ECU 100, and outputs the upper limit discharge flow rate Qmax of the high-pressure fuel pump 5 to the flow rate restriction unit 120. More specifically, the energization start angle calculation unit 130 refers to, for example, a static characteristic map of the high-pressure fuel pump 5 corresponding to the rotation speed Re of the engine 2 and the voltage Vb of the battery.

[0040] The static characteristic map of the high-pressure fuel pump 5 is, for example, a graph in which the horizontal axis is the energization start phase θon [deg] and the vertical axis is the discharge flow rate Q [mg / stroke] of the high-pressure fuel pump 5. The energization start angle calculation unit 130 outputs the energization start phase θon corresponding to the inputted restricted flow value QL or flow target value QT based on the static characteristic map of the high-pressure fuel pump 5, for example.

[0041] The energization start angle limiting unit 140 receives the energization start phase θon output from the energization start angle calculating unit 130 as input and outputs a energization start phase θLon obtained by limiting the input energization start phase θon by the phase of the bottom dead center (BDC) and the phase of the top dead center (TDC) of the plunger 54.

[0042] The energization end angle calculation unit 150 receives as input, for example, a crank angle φcra and a cam angle λcam detected by a crank angle sensor and a cam angle sensor for detecting the rotation angles of the crankshaft and camshaft of the engine 2. The energization end angle calculation unit 150 outputs an energization end phase θoff of the solenoid valve 52 of the high-pressure fuel pump 5 based on the crank angle φcra and the cam angle λcam.

[0043] The energization end angle limiting unit 160 receives the energization end phase θoff output from the energization end angle calculating unit 150 as an input and outputs a energization end phase θLoff obtained by limiting the input energization end phase θoff by the phases of BDC and TDC of the plunger 54 .

[0044] The solenoid valve control unit 170 generates a driving pulse DP for driving the solenoid of the solenoid valve 52 of the high-pressure fuel pump 5 based on the input energization start phase θLon and energization end phase θLoff, and outputs it to the solenoid valve 52 of the high-pressure fuel pump 5. More specifically, the solenoid valve control unit 170 takes, for example, a phase detection value θd of an angle sensor that detects the phase of the plunger 54, the energization start phase θLon, and the energization end phase θLoff as input.

[0045] The solenoid valve control unit 170, for example, starts energizing the solenoid valve 52 when the phase detection value θd is equal to the energization start phase θLon, and opens the flow path 57. In addition, the solenoid valve control unit 170, for example, ends energizing the solenoid valve 52 when the phase detection value θd is equal to the energization end phase θLoff, and closes the flow path 57. As a result, fuel of a flow rate corresponding to the restricted flow value QL or the flow target value QT output from the flow restriction unit 120 is supplied to the pressurizing chamber 53 of the high-pressure fuel pump 5, and is discharged from the high-pressure fuel pump 5 to the fuel injection device 6.

[0046] Figure 6 Yes Description Figure 2 The operation of the control device for an internal combustion engine of the present embodiment will be described below based on a comparison with a control device for an internal combustion engine of a comparative example.

[0047] Figure 6 The upper left graph of is a graph showing time changes in the pressure target value Pt and the pressure detection value Pd of the high-pressure fuel pump 5 controlled by the control device for the internal combustion engine of the comparative example. Figure 6 The lower left graph of is a graph showing time changes in the flow rate target value QT of the high-pressure fuel pump 5 controlled by the control device for the internal combustion engine of the comparative example and the actual discharge flow rate Qd detected by the flow rate sensor.

[0048] The difference between the control device for the internal combustion engine of the comparative example and the ECU 100 of the control device for the internal combustion engine of the present embodiment is that the control device for the internal combustion engine of the comparative example does not have Figure 2 The flow rate limiting unit 120 is shown. The other structures of the control device of the internal combustion engine of the comparative example are the same as those of the control device of the internal combustion engine of the present embodiment. In the control device of the internal combustion engine of the comparative example, the discharge pressure of the high-pressure fuel pump 5, that is, the pressure detection value Pd is feedback-controlled by the feedback control unit 110.

[0049] For example, it is assumed that when a vehicle equipped with the engine system 1 suddenly starts, the detection value of the accelerator opening sensor 7, that is, the accelerator opening increases rapidly. In this case, in the control device for the internal combustion engine of the comparative example, the feedback control unit 110 is input with the following information: Figure 6 As a result, the pressure target value Pt is stepped as shown in the upper left graph of FIG. Figure 6 As shown in the lower left graph of , the flow rate target value QT outputted from the feedback control unit 110 increases sharply, and the flow rate target value QT is limited to the upper limit discharge flow rate Qmax by, for example, the energization start angle calculation unit 130 .

[0050] However, in the control device of the internal combustion engine of the comparative example which does not include the flow rate limiting unit 120, the discharge flow rate Qd of the fuel of the high-pressure fuel pump 5 increases and exceeds the flow rate target value QT. As a result, in the control device of the internal combustion engine of the comparative example, the pressure detection value Pd which is the discharge pressure of the high-pressure fuel pump 5 increases sharply, an overshoot which greatly exceeds the pressure target value Pt occurs, and the discharge pressure of the fuel of the high-pressure fuel pump 5 pulsates.

[0051] That is, in the control device of the internal combustion engine of the comparative example not having the flow rate limiting unit 120, there is a problem that the stability of the transient response of the discharge pressure of the fuel of the high-pressure fuel pump 5 to the pressure target value Pt is reduced. In the control device of the internal combustion engine of such a comparative example, when the overshoot of the discharge pressure of the high-pressure fuel pump 5 is suppressed by the gain adjustment of the feedback control unit 110, there is a possibility that the responsiveness of the discharge pressure of the high-pressure fuel pump 5 to the pressure target value Pt is reduced.

[0052] On the other hand, the ECU 100 as the control device of the internal combustion engine constituting the present embodiment controls the discharge pressure of the fuel discharged from the high-pressure fuel pump 5 to the fuel injection device 6. As described above, the high-pressure fuel pump 5 includes: a pressurizing chamber 53 into which the fuel is introduced from the fuel tank 3 via the low-pressure fuel pump 4; an electromagnetic valve 52 that opens and closes a flow path 57 for introducing the fuel to the pressurizing chamber 53; and a plunger 54 that pressurizes the fuel introduced into the pressurizing chamber 53. As described above, the fuel injection device 6 injects the fuel into the combustion chamber of the engine 2 as the internal combustion engine. As described above, the ECU 100 includes the feedback control unit 110, the flow rate limiting unit 120, and the energization start angle calculation unit 130. The pressure detection value Pd of the pressure sensor 63 of the fuel discharged from the high-pressure fuel pump 5 to the fuel injection device 6 and the pressure target value Pt of the discharge pressure of the high-pressure fuel pump 5 are input to the feedback control unit 110. In addition, the feedback control unit 110 outputs the pressure deviation ΔP between the pressure detection value Pd and the pressure target value Pt, and the flow rate target value QT of the discharge flow rate of the high-pressure fuel pump 5 based on the input pressure target value Pt and the pressure detection value Pd. The flow rate limiting unit 120 takes the pressure deviation ΔP and the flow rate target value QT as inputs, and outputs the restricted flow rate value QL that restricts the flow rate target value QT according to the value of the pressure deviation ΔP and the change amount dΔP. The energization start angle calculation unit 130 calculates the energization start phase θon in the reciprocating motion of the plunger 54 according to the restricted flow rate value QL, and starts energizing the solenoid valve 52 of the high-pressure fuel pump 5 at the energization start phase θon.

[0053] With such a configuration, the control device for the internal combustion engine of the present embodiment is the same as the comparative example described above. When the feedback control unit 110 is input Figure 6 When the step-shaped pressure target value Pt shown in the upper right graph is reached, the following actions are performed. Figure 6 As shown in the lower right graph of , the flow target value QT outputted from the feedback control unit 110 increases sharply. For example, the flow target value QT is limited to the upper limit discharge flow rate Qmax based on the static characteristics of the high pressure fuel pump 5 by the energization start angle calculation unit 130 .

[0054] In addition, due to the rapid increase in the flow rate target value QT of the discharge flow rate of the high-pressure fuel pump 5, the pressure detection value Pd detected by the pressure sensor 63 of the fuel discharged from the high-pressure fuel pump 5 to the fuel injection device 6 rapidly increases. And the pressure deviation ΔP between the pressure target value Pt and the pressure detection value Pd decreases, for example, the change amount dΔP of the pressure detection value Pd increases until the pressure detection value Pd reaches the pressure target value Pt [62.3%] or so.

[0055] Here, as described above, the control device for the internal combustion engine of the present embodiment includes the flow rate limiting unit 120 which outputs the limited flow rate value QL limiting the flow rate target value QT based on the value of the pressure deviation ΔP and the change amount dΔP. Figure 6 As shown in the upper right and lower right graphs of , before the pressure detection value Pd exceeds the pressure target value Pt, the flow rate target value QT is limited to a lower limited flow rate value QL1 by the flow rate limiting unit 120 .

[0056] As a result, the energization start angle calculation unit 130 calculates the energization start phase θon in the reciprocating motion of the plunger 54 based on the restricted flow value QL1 output from the flow restriction unit 120, and starts energizing the solenoid valve 52 of the high-pressure fuel pump 5 at the energization start phase θon. As a result, the increase in the discharge flow rate Qd of the high-pressure fuel pump 5 is restricted, and the change amount dΔP of the pressure deviation ΔP between the pressure detection value Pd of the fuel discharged from the high-pressure fuel pump 5 to the fuel injection device 6 and the pressure target value Pt is reduced. As a result, the discharge flow rate Qd of the high-pressure fuel pump 5 is prevented from exceeding the flow target value QT, and the pressure detection value Pd of the fuel discharged from the high-pressure fuel pump 5 to the fuel injection device 6 is prevented from overshooting beyond the pressure target value Pt.

[0057] Furthermore, the flow rate limiting unit 120 limits the flow rate target value QT to a limited flow rate value QL2 which is larger than the limited flow rate value QL1 and smaller than the flow rate target value QT based on the change amount dΔP of the reduced pressure deviation ΔP. Thus, an excessive decrease in the discharge flow rate Qd of the high-pressure fuel pump 5 is prevented, and the responsiveness of the pressure detection value Pd of the fuel discharged from the high-pressure fuel pump 5 to the fuel injection device 6 to the pressure target value Pt is improved.

[0058] In more detail, in the control device for the internal combustion engine of the present embodiment, the flow rate limiting unit 120 includes a limiting value determining unit 122, a limiting flow value calculating unit 123, and a limiting processing unit 124. The limiting value determining unit 122 determines a larger limiting value LV as the value of the pressure deviation ΔP decreases and the amount of change dΔP of the pressure deviation ΔP increases. The limiting flow value calculating unit 123 calculates the limiting flow value QL by subtracting the limiting value LV from the upper limit discharge flow rate Qmax based on the static characteristics of the high-pressure fuel pump 5. The limiting processing unit 124 outputs the flow rate target value QT when the flow rate target value QT does not exceed the limiting flow value QL, and outputs the limiting flow value QL when the flow rate target value QT exceeds the limiting flow value QL.

[0059] With such a configuration, the control device for the internal combustion engine of this embodiment is as follows: Figure 6As shown in the upper right graph of , when the step-shaped pressure target value Pt is input to the feedback control unit 110, the pressure detection value Pd, which is the discharge pressure of the high-pressure fuel pump 5, increases sharply. As a result, if the pressure deviation ΔP between the pressure target value Pt and the pressure detection value Pd decreases and the change amount dΔP of the pressure deviation ΔP increases, a larger limit value LV is determined.

[0060] Thus, the flow target value QT is limited to a smaller limited flow value QL1 obtained by subtracting a larger limited value LV from the upper limit discharge flow rate Qmax. Therefore, according to the control device for the internal combustion engine of the present embodiment, it is possible to prevent the pressure detection value Pd from overshooting the pressure target value Pt, and to improve the stability of the transient response of the discharge pressure of the high-pressure fuel pump 5 to the pressure target value Pt.

[0061] After that, the change amount dΔP of the pressure deviation ΔP decreases, thereby determining a smaller limit value LV. As a result, Figure 6 As shown in the lower right graph of , the flow target value QT is limited to a relatively large limited flow value QL2 obtained by subtracting a relatively small limited value LV from the upper limit discharge flow rate Qmax. Therefore, according to the control device for the internal combustion engine of the present embodiment, it is possible to prevent the discharge flow rate Qd of the high-pressure fuel pump 5 from being excessively reduced, and it is possible to improve the responsiveness of the transient response of the pressure detection value Pd of the fuel discharged from the high-pressure fuel pump 5 to the fuel injection device 6 to the pressure target value Pt.

[0062] In addition, the control device for the internal combustion engine of the present embodiment further includes Figure 2 The solenoid valve control unit 170 shown in FIG. The solenoid valve control unit 170 receives as input the phase detection value θd of the angle sensor detecting the phase of the plunger 54 of the high-pressure fuel pump 5 and the energization start phase θLon. When the phase detection value θd is equal to the energization start phase θLon, the solenoid valve control unit 170 starts energizing the solenoid valve 52 and opens the flow path 57.

[0063] With such a configuration, at the moment when the phase of the reciprocating motion of the plunger 54 is equal to the energization start phase θLon, the solenoid of the electromagnetic valve 52 of the high-pressure fuel pump 5 starts to be energized, thereby opening the flow path 57. As a result, the fuel is introduced from the fuel tank 3 to the pressurizing chamber 53 of the high-pressure fuel pump 5 via the low-pressure fuel pump 4, and is pressurized in the pressurizing chamber 53 of the high-pressure fuel pump 5, and the fuel of the flow rate corresponding to the restricted flow value QL or the flow target value QT is discharged from the high-pressure fuel pump 5 to the fuel injection device 6.

[0064] As described above, according to the present embodiment, it is possible to provide a control device for an internal combustion engine that can simultaneously improve the stability and responsiveness of the transient response of the discharge pressure of the high-pressure fuel pump 5 to the pressure target value Pt. In addition, the control device for an internal combustion engine of the present embodiment is not limited to the above-mentioned embodiment. Figure 7 and Figure 8 Several modified examples of the above-described embodiment will be described.

[0065] Figure 7 Yes means Figure 3 The flow rate limiting unit 120 may not have, for example, Figure 3 The flow rate limit value calculation unit 123 is shown. Figure 7 In the modified example of the control device for the internal combustion engine shown in FIG. 1 , the flow rate limiting unit 120 includes a change amount calculation unit 121, a limit value determination unit 122, and a limit processing unit 124. As in the above-described embodiment, the change amount calculation unit 121 takes the pressure deviation ΔP as an input and calculates the change amount dΔP of the pressure deviation ΔP. As in the above-described embodiment, the limit value determination unit 122 determines a larger limit value LV as the value of the pressure deviation ΔP decreases and the change amount dΔP of the pressure deviation ΔP increases. Then, the limit processing unit 124 calculates a limit flow value QL obtained by subtracting the limit value LV from the flow target value QT.

[0066] The control device for the internal combustion engine of the above-mentioned modified example can also achieve the same effect as the control device for the internal combustion engine of the above-mentioned embodiment. Therefore, in this modified example, a control device for the internal combustion engine can also be provided that can simultaneously improve the stability and responsiveness of the transient response of the discharge pressure of the high-pressure fuel pump 5 to the pressure target value Pt.

[0067] In the control device for the internal combustion engine of the above-mentioned embodiment and the modified example, the flow rate limiting unit 120 limits the value of the flow rate target value QT to the limited flow rate value QL obtained by subtracting the limit value LV from the upper limit discharge flow rate Qmax or the flow rate target value QT. However, the control device for the internal combustion engine according to the present invention may limit the flow rate target value QT in other ways.

[0068] For example, in Figure 7 In the example shown, the flow rate limiting unit 120 may also include: a limiting value determining unit 122 that determines a limiting value LV based on the value of the pressure deviation ΔP and the change amount dΔP; and a limiting processing unit 124 that outputs a limiting flow rate value QL in which the change amount of the flow rate target value QT is limited by the limiting value LV. That is, the limiting value LV is a value for limiting the change amount of the flow rate target value QT, which is the difference between the previous value and the current value of the flow rate target value QT.

[0069] The control device for the internal combustion engine according to this modified example can not only achieve the same effect as the control device for the internal combustion engine according to the above-mentioned embodiment, but also can cope with the high-pressure fuel pump 5 and the fuel injection device 6 having large individual differences in static characteristics. That is, in the case where the individual differences in static characteristics of the high-pressure fuel pump 5 and the fuel injection device 6 are large, it is more effective to limit the amount of change of the flow rate target value QT than to limit the upper limit value (absolute value) of the flow rate target value QT output from the feedback control unit 110.

[0070] Figure 8 Yes means Figure 2 A block diagram of an example of a feedback control unit 110 of a control device for an internal combustion engine. Figure 8 In the example shown, the feedback control unit 110 includes a pressure deviation calculation unit 111, a proportional term calculation unit 112, an integral term calculation unit 113, and an addition unit 114. The pressure deviation calculation unit 111 calculates the pressure deviation ΔP by taking the pressure target value Pt and the pressure detection value Pd as input. The proportional term calculation unit 112 calculates the proportional term based on the pressure deviation ΔP. The integral term calculation unit 113 calculates the integral term based on the pressure deviation ΔP. The addition unit 114 adds the proportional term and the integral term to calculate the flow rate target value QT. Figure 2 and Figure 8 As shown, for example, when the flow target value QT is limited by the limit flow value QL, the integral term calculation unit 113 receives the input of the limit determination LD from the flow limiter 120. When the flow target value QT is limited by the limit flow value QL, that is, when the limit determination LD is input, the integral term calculation unit 113 stops the calculation of the integral term.

[0071] In this way, when the flow target value QT is limited by the limited flow value QL, the flow target value QT can be prevented from being overcorrected, that is, the accumulation of the integral amount, by stopping the calculation of the integral term of the integral term calculation unit 113 in the feedback control unit 110. Therefore, it is possible to more effectively prevent the pressure detection value Pd of the discharge pressure of the high-pressure fuel pump 5 from overshooting the pressure target value Pt. In addition, the calculation of the integral term can be stopped, for example, by maintaining the calculation value, setting the calculation value to zero, or subtracting the overcorrection amount when the flow target value QT is limited from the integral term calculation value.

[0072] Although the embodiments and modifications of the present disclosure have been described in detail above using the drawings, the specific configuration is not limited to these embodiments and modifications, and design changes and the like within the scope not departing from the gist of the present invention are also included in the present disclosure. Explanation of symbols

[0073] 2 Engine (internal combustion engine) 3 Fuel tank 4 Low pressure fuel pump 5 High-pressure fuel pump 52 Solenoid valve 53 Pressurized Room 54 Plunger 57 flow path 6 Fuel injection device 63 Pressure Sensor 100ECU (Internal combustion engine control unit) 110 Feedback Control Unit 111 Pressure deviation calculation unit 112 Proportional term calculation unit 113 Integral Term Calculation Section 114 Addition 120 Flow restriction unit 122 Limit value determination unit 123 Flow rate limit calculation unit 124 Restricted Processing Department 130 Energization start angle calculation unit 170 Solenoid valve control unit dΔP Change in pressure deviation LV limit value Pd pressure detection value Pt pressure target value QL limit flow value Qmax upper limit discharge flow QT flow target value ΔP Pressure deviation θon Power-on start phase.

Claims

1. A control device for an internal combustion engine, which controls the discharge pressure of fuel discharged from a high-pressure fuel pump to a fuel injection device, the high-pressure fuel pump comprising: a pressurizing chamber into which the fuel is introduced from a fuel tank via a low-pressure fuel pump; and a solenoid valve that opens and closes a flow path for introducing the fuel into the pressurizing chamber; and a plunger that pressurizes the fuel introduced into the pressurizing chamber, the fuel injection device injects the fuel into a combustion chamber of an internal combustion engine, and the control device for the internal combustion engine is characterized by comprising: a feedback control unit that receives as input a pressure detection value of a pressure sensor of the fuel discharged from the high-pressure fuel pump to the fuel injection device and a pressure target value of the discharge pressure, and outputs a pressure deviation between the pressure detection value and the pressure target value, and a flow rate target value of a discharge flow rate of the high-pressure fuel pump; a flow rate limiting unit that takes the pressure deviation and the flow rate target value as inputs and outputs a limited flow rate value obtained by limiting the flow rate target value according to the value and variation of the pressure deviation; as well as An energization start angle calculation unit calculates an energization start phase in the reciprocating motion of the plunger based on the limit flow rate value, and starts energizing the solenoid valve of the high-pressure fuel pump at the energization start phase.

2. The control device for an internal combustion engine according to claim 1, characterized in that: The flow restriction unit has: a limit value determination section that determines a larger limit value as the value of the pressure deviation decreases and the amount of change in the pressure deviation increases; and A restriction processing unit calculates the restricted flow rate value by subtracting the restricted value from the target flow rate value.

3. The control device for an internal combustion engine according to claim 1, characterized in that: The flow restriction unit has: a limit value determination unit that determines a larger limit value as the value of the pressure deviation decreases and the amount of change in the pressure deviation increases; a limit flow value calculation unit that calculates the limit flow value by subtracting the limit value from an upper limit discharge flow rate based on static characteristics of the high-pressure fuel pump; as well as A restriction processing unit is configured to output the target flow rate value when the target flow rate value does not exceed the limit flow rate value, and to output the limit flow rate value when the target flow rate value exceeds the limit flow rate value.

4. The control device for an internal combustion engine according to claim 1, characterized in that: The flow restriction unit has: a limit value determination section that determines a limit value based on the value and the change amount of the pressure deviation; and A restriction processing unit outputs the restricted flow rate value obtained by restricting the amount of change of the flow rate target value by the restricted value.

5. The control device for an internal combustion engine according to claim 1, characterized in that: The feedback control unit includes: a pressure deviation calculation unit that calculates the pressure deviation; a proportional term calculating unit, which calculates a proportional term according to the pressure deviation; an integral term calculating unit, which calculates the integral term according to the pressure deviation; and an adding unit that adds the proportional term and the integral term to calculate the flow rate target value, The integral term calculation unit stops calculation of the integral term when the flow rate target value is limited by the limit flow rate value.

6. The control device for an internal combustion engine according to claim 1, characterized in that: It also has an electromagnetic valve control unit, which takes a phase detection value and the power-on start phase as inputs, and starts to energize the electromagnetic valve to open the flow path when the phase detection value is equal to the power-on start phase. The phase detection value comes from an angle sensor that detects the phase of the plunger.

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