JP2014020207A - Fuel injection control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device of an internal combustion engine which detects a driving current value of each fuel injection valve and reduces power consumption without increasing circuit parts, in a driving circuit for driving both of a port fuel injection valve and a direct fuel injection valve.SOLUTION: A driving current IDP supplied to a port fuel injection valve 3 and a driving current IDD supplied to a direct fuel injection valve 4 are detected by a common current detecting resistor R1 and a CPU 11. Duty feedback control of a driving voltage that causes a retention current value IHLDD for valve-opening state retention of the direct fuel injection valve 4 to accord with a target current value ICMDD is performed. At the same time, duty feedback control of a driving voltage that causes a retention current value IHLDP for valve-opening state retention of the port fuel injection valve 3 to accord with a target current value ICMDP is performed.

Description

  The present invention relates to a fuel injection control device for an internal combustion engine, and more particularly to a fuel injection control device for an internal combustion engine that includes a fuel injection valve that injects fuel into an intake passage and a fuel injection valve that injects fuel into a combustion chamber.

  Patent Document 1 discloses a fuel injection valve that injects fuel into an intake passage (hereinafter referred to as “port fuel injection valve”) and a fuel injection valve that injects fuel into a combustion chamber (hereinafter referred to as “in-cylinder fuel injection valve”). Is shown, and Patent Document 2 specifically shows a drive circuit for driving the in-cylinder fuel injection valve.

  In the driving circuit shown in Patent Document 2, the driving current value supplied to the solenoid of the in-cylinder fuel injection valve is detected, and the power supply is set so that the detected valve-opening holding current value falls within a predetermined current value range. The switching element provided between the solenoid and the solenoid is on / off controlled.

Japanese Patent Laid-Open No. 2007-92088 Japanese Patent No. 4474423

  In the drive circuit of the port fuel injection valve, the feedback control of the holding current value as shown in Patent Document 2, that is, the drive current value supplied to the solenoid of the port fuel injection valve is detected, and the detected drive current value is set. Accordingly, the on / off control of the switching element is not performed.

  Therefore, in the drive circuit of the port fuel injection valve, the drive voltage is always applied to the solenoid even during the period in which the holding current for maintaining the valve open state is supplied, so there is room for improvement from the viewpoint of reducing power consumption. there were.

  The present invention has been made paying attention to this point, and in the drive circuit that drives both the port fuel injection valve and the in-cylinder fuel injection valve, the drive current value of each fuel injection valve is increased without increasing circuit components. An object of the present invention is to provide a fuel injection control device that can detect and reduce power consumption.

  In order to achieve the above object, the invention described in claim 1 includes a first fuel injection valve (3) for injecting fuel into the intake passage (2) of the internal combustion engine (1), and fuel into the combustion chamber of the engine. In a fuel injection control device for an internal combustion engine comprising a second fuel injection valve (4) for injecting, a first drive circuit (Q3, L1, Q4) for opening and closing the first fuel injection valve (3), and the first A second drive circuit (Q1, Q2, L2, Q5) for opening and closing the fuel injection valve (4), and a drive current value (IDP) of the first fuel injection valve connected to the first and second drive circuits; ) And current detection means (R1, CPU11) capable of detecting the drive current value (IDD) of the second fuel injection valve, and fuel for performing fuel injection control by the first and second fuel injection valves (3, 4) Injection control means, wherein the fuel injection control means is detected by the first First drive control for controlling the drive of the first fuel injection valve (3) via the first drive circuit in accordance with a first drive current value (IDP) which is a drive current value of the fuel injection valve (3). And a second drive current value (IDD), which is a detected drive current value of the second fuel injection valve, for controlling the drive of the second fuel injection valve via the second drive circuit. 2 drive control means, and performs the fuel injection control so that a valve opening period (TIPCMD) of the first fuel injection valve and a valve opening period (TIDCMD) of the second fuel injection valve do not overlap, In accordance with the first drive current value (IDP), the first drive control means has a holding current value (IHLDP) for holding an open state after the opening of the first fuel injection valve is a first target value. The driving voltage (VDP) of the first fuel injection valve so as to coincide with (ICMDP) Duty feedback control is performed, and the second drive control means performs a holding current value (IHLDD) for holding the valve open state after the second fuel injection valve is opened according to the second drive current value (IDD). ) Is a duty feedback control of the drive voltage (VDD) of the second fuel injector so that the second target value (ICMDD) matches.

  According to the first aspect of the present invention, the first drive current value supplied to the first fuel injection valve (port fuel injection valve) and the second drive current value supplied to the second fuel injection valve (in-cylinder fuel injection valve). The drive current value is detected by a common current detecting means, duty feedback control is performed to match the holding current value for maintaining the open state of the second fuel injection valve with the second target value, and the first fuel injection valve Duty feedback control is performed to match the holding current value for maintaining the valve open state with the first target value. Since the first drive current value is performed by current detection means for detecting the second drive current value, it is not necessary to add a current detection circuit for detecting the first drive current value, and an increase in cost is avoided. Can do. Moreover, power consumption can be reduced by performing duty feedback control also about the 1st fuel injection valve.

It is a figure showing a fuel injection control device of an internal-combustion engine concerning one embodiment of the present invention. It is a circuit diagram which shows the structure of the fuel injection valve drive part contained in the electronic control unit (ECU5) shown in FIG. It is a time chart which shows transition of the drive voltage and drive current of the cylinder fuel injection valve shown in FIG. It is a time chart which shows transition of the drive voltage and drive current of the port fuel injection valve shown in FIG. It is a flowchart of fuel injection valve drive control.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a fuel injection control device for an internal combustion engine (hereinafter referred to as “engine”) 1 according to an embodiment of the present invention. The four-cylinder engine 1 is arranged on the cylinder side slightly upstream of the intake valve of each cylinder. And a port fuel injection valve 3 for injecting fuel into the intake passage 2 (intake port), and an in-cylinder fuel injection valve 4 for injecting fuel directly into the combustion chamber of each cylinder. Each injection valve 3, 4 is connected to a fuel pump (not shown) and is electrically connected to an electronic control unit (hereinafter referred to as “ECU”) 5. The valve time (fuel injection time) is controlled.

  A battery 6 as a power source is connected to the ECU 5, and electric power for operating the ECU 5 and electric power for driving the port fuel injection valve 3 and the in-cylinder fuel injection valve 4 are supplied from the battery 6.

  FIG. 2 is a circuit diagram showing a configuration of a fuel injection valve drive unit included in the ECU 5, and supplies a drive current to the solenoid L 1 of one port fuel injection valve 3 and the solenoid L 2 of one in-cylinder fuel injection valve 4. The circuit configuration is shown. The circuits for supplying the drive current to the solenoids of the other three port fuel injection valves 3 and the in-cylinder fuel injection valve 4 are similarly configured.

  The fuel injection valve drive unit shown in FIG. 2 supplies field effect transistors (hereinafter referred to as “FETs”) Q1 and Q2 as switching elements for switching on and off the power supply voltage supplied to one end of the solenoid L2, and supplies one end of the solenoid L1. FET Q3 as a switching element for performing on / off switching of the power supply voltage to be performed, FETs Q4 and Q5 as switching elements for switching connection / disconnection between the other ends of the solenoids L1, L2 and the ground, and diodes D1-D3 A resistor R1, a CPU 11, a booster circuit 12, and drive circuits 13 and 14, a control signal is supplied from the CPU 11 to the FETs Q1 to Q5, and one end of the resistor R1 is connected to the current detection terminal VIDIN of the CPU 11. It is connected. Since the voltage value VID supplied to the current detection terminal VIDIN is proportional to the current value flowing through the resistor R1, the drive current value supplied to the solenoids L1 and L2 is detected by the voltage value VID.

  The booster circuit 12 boosts an output voltage (hereinafter referred to as “first power supply voltage”) VS1 (for example, 14V) of the battery 4 and outputs a second power supply voltage VS2 (for example, 40V). The first power supply voltage VS1 is supplied to one end of the solenoid L1 through the FET Q3 and is supplied to one end of the solenoid L2 through the FET Q2 and the diode D1. The second power supply voltage VS2 is supplied to one end of the solenoid L2 via the FET Q1. The diode D1 is provided to prevent a current from flowing from the boosted power supply line of the second power supply voltage VS2 to the power supply line of the first power supply voltage VS1.

The other end of the solenoid L1 is connected to one end of the resistor R1 through the FET Q4, and the other end of the solenoid L2 is connected to one end of the resistor R1 through the FET Q5.
The voltage control signal output from the output terminal BSHSW1 of the CPU 11 is supplied to the gate of the FET Q1 via the drive circuit 13, and the voltage control signals output from the output terminals BTHSW1 and BTHSW2 of the CPU 11 are respectively connected via the drive circuit 13. It is supplied to the gates of the FETs Q2 and Q3. The low-side control signals output from the output terminals LOSW1 and LOSW2 of the CPU 11 are supplied to the gates of the FETs Q4 and Q5 via the drive circuit 14, respectively.

  FIGS. 3A and 3B show changes in the drive voltage VDD and the drive current IDD supplied to the solenoid L2 when the in-cylinder fuel injection valve 4 is opened, and FIG. 3C shows in-cylinder injection. It is a time chart which shows transition of execution flag FDINJ. A period TIDCMD from time tISD to tIED corresponds to a period during which the valve opening command signal is output (hereinafter referred to as “in-cylinder injection command period TIDCMD”).

  In a period TVS2 from time tISD to tSWD, the FET Q1 is turned on and the second power supply voltage VS2 is supplied to the solenoid L2 (overexcitation control is executed). In the period TVS1 from time tSWD to tIED, the FET Q1 is turned off, and the FET Q2 is turned on / off so that the holding current value IHLDD for maintaining the in-cylinder fuel injection valve 4 in the open state coincides with the target current value ICMDD. Controlled (holding control is executed). The FET Q5 is turned on during the in-cylinder injection command period TIDCMD, and the FET Q4 is kept off. Therefore, the drive current is supplied only to the solenoid L2.

  FIGS. 4A and 4B show transitions of the drive voltage VDP and the drive current IDP supplied to the solenoid L1 when the port fuel injection valve 3 is opened, and FIG. 4C shows the port injection execution flag. It is a time chart which shows transition of FPINJ. A period TIPCMD from time tISP to tIEP corresponds to a period during which the valve opening command signal is output (hereinafter referred to as “port injection command period TIPCMD”).

  Only the first power supply voltage VS1 is applied to drive the port fuel injection valve 3. During the period from time tISP to tSWP, the FET Q3 is turned on and the first power supply voltage VS1 is supplied to the solenoid L1 (overexcitation control). Is executed). During the period from time tSWP to tIEP, the FET Q3 is ON / OFF duty controlled so that the holding current value IHLDP for holding the open state of the port fuel injection valve 3 coincides with the target current value ICMDP (holding control is performed). Executed). The FET Q4 is turned on during the port injection command period TIPCMD, and the FET Q5 is kept off. Therefore, the drive current is supplied only to the solenoid L1.

  In the present embodiment, the port fuel injection valve 3 and the in-cylinder fuel injection valve 4 are controlled so that the valve opening periods do not overlap, and the holding current values IHLDD and IHLDP are both voltage values VID input to the current detection terminal VIDIN. Detected by.

  FIG. 5 is a flowchart of a process for driving the port fuel injection valve 3 and the in-cylinder fuel injection valve 4 in accordance with the fuel injection command signal calculated in accordance with the engine operating state and executing fuel injection. This process is executed by the CPU 11.

  In step S11, it is determined whether or not the in-cylinder injection execution flag FDINJ is “1”. If the answer to step S11 is affirmative (YES), the in-cylinder fuel injection valve 4 is in excess during the period from time tISD to tSWD. Excitation control is executed (step S15), and then holding control of the in-cylinder fuel injection valve 4 is executed during the period from time tSWD to tIED (step S16). By steps S15 and S16, fuel injection by the in-cylinder fuel injection valve 4 is executed.

  If the answer to step S11 is negative (NO), it is determined whether or not a port injection execution flag FPINJ is “1” (step S12). If this answer is affirmative (YES), overexcitation control of the port fuel injection valve 3 is executed during the period from time tISP to tSWP (step S13), and then the port fuel injection valve 3 is operated during the period from time tSWP to tIEP. Holding control is executed (step S14). By steps S13 and S14, fuel injection by the port fuel injection valve 3 is executed.

  As described above, in the present embodiment, the drive current IDP supplied to the port fuel injection valve 3 and the drive current IDD supplied to the in-cylinder fuel injection valve 4 are detected by the common current detection resistor R1 and the CPU 11, and the port Holding control (duty feedback control) is performed so that the holding current value IHLDP for holding the opened state of the fuel injection valve 3 matches the target current value ICMDP. Since the drive current IDP supplied to the port fuel injection valve 3 is performed using the current detection resistor R1 used to detect the drive current IDD of the in-cylinder fuel injection valve 4, the drive current IDP is detected. Therefore, it is not necessary to add a resistor and an input terminal of the CPU 11, and an increase in cost can be avoided. In addition, since the port fuel injection valve 3 is also subjected to duty feedback control for on / off duty control of the FET Q3 in accordance with the detected holding current value IHLDP, power consumption can be reduced as compared with the case where the FET Q3 is always on.

  In this embodiment, the port fuel injection valve 3 corresponds to a first fuel injection valve, the in-cylinder fuel injection valve 4 corresponds to a second fuel injection valve, the FET Q4 and the solenoid L1 constitute a first drive circuit, and the FET Q1 , Q2, Q5 and solenoid L2 constitute a second drive circuit, resistor R1 and CPU 11 constitute current detection means, and CPU 11 constitutes fuel injection control means, first drive control means and second drive control means. .

  The present invention is not limited to the embodiment described above, and various modifications can be made. For example, in the above-described embodiment, an example in which the present invention is applied to a fuel injection control device for a four-cylinder engine has been described. Applicable to the device. The present invention can also be applied to a fuel injection control device such as a marine vessel propulsion engine such as an outboard motor having a vertical crankshaft.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake passage 3 Port fuel injection valve (1st fuel injection valve)
4 In-cylinder fuel injection valve (second fuel injection valve)
11 CPU (current detection means, fuel injection control means, first drive control means, second drive control means)
12 Booster circuit (second drive circuit)
L1 solenoid (first drive circuit)
L2 solenoid (second drive circuit)
Q3, Q4 Field effect transistor (first drive circuit)
Q1, Q2, Q5 Field effect transistor (second drive circuit)
R1 resistance (current detection means)

Claims (1)

In a fuel injection control device for an internal combustion engine, comprising: a first fuel injection valve that injects fuel into an intake passage of the internal combustion engine; and a second fuel injection valve that injects fuel into a combustion chamber of the engine.
A first drive circuit for opening and closing the first fuel injection valve;
A second drive circuit for opening and closing the second fuel injection valve;
Current detection means connected to the first and second drive circuits and capable of detecting a drive current value of the first fuel injection valve and a drive current value of the second fuel injection valve;
Fuel injection control means for performing fuel injection control by the first and second fuel injection valves,
The fuel injection control means includes
First drive control means for performing drive control of the first fuel injection valve via the first drive circuit according to a detected first drive current value that is a drive current value of the first fuel injection valve;
Second drive control means for performing drive control of the second fuel injection valve via the second drive circuit in accordance with a detected second drive current value that is a drive current value of the second fuel injection valve. Have
Performing the fuel injection control so that the opening period of the first fuel injection valve and the opening period of the second fuel injection valve do not overlap,
In accordance with the first drive current value, the first drive control means is configured so that a holding current value for holding the valve open state after the opening of the first fuel injection valve coincides with a first target value. Perform duty feedback control of the drive voltage of the first fuel injection valve,
In accordance with the second drive current value, the second drive control means is configured so that a holding current value for holding the valve open state after the second fuel injection valve is opened matches a second target value. A fuel injection control device for an internal combustion engine, which performs duty feedback control of a drive voltage of a second fuel injection valve.

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