JP2016094910A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of exhaust emission when self-starting of an internal combustion engine is performed.SOLUTION: When load starting of an internal combustion engine 12 is selected, target fuel pressure Pireq that is a target value of pressure of fuel supplied to a fuel injection valve is set to be higher than a predetermined value P0 (S102). When self-starting of the internal combustion engine 12 is selected, the target fuel pressure Pireq is set to be lower than the predetermined value P0 (S103). Thus, when the self-starting of the internal combustion engine 12 is selected, even if intake air amount is small, this control device can inhibit an air fuel ratio from becoming rich, so as to enable suppression of deterioration of exhaust emission.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an internal combustion engine control device, and more particularly to a control device that selectively performs either a self-sustained start or a load start when starting an internal combustion engine in which the pressure of fuel supplied to a fuel injection valve is variable.

  Patent Document 1 below discloses that when starting an internal combustion engine, either an independent start with a small throttle opening or a load start with a large throttle opening is selectively performed.

JP 2012-7521 A JP 2009-269430 A JP 2011-73474 A

  In Patent Document 1, when the self-sustained start of the internal combustion engine is selected, the throttle opening is small and the intake air amount is small. Therefore, if the pressure of the fuel supplied to the fuel injection valve is high, the fuel injection amount is smaller than the intake air amount. It becomes excessive and the air-fuel ratio tends to become excessively small. As a result, exhaust emission may be deteriorated.

  An object of the present invention is to suppress deterioration of exhaust emission when an internal combustion engine is started independently.

  The control apparatus for an internal combustion engine according to the present invention employs the following means in order to achieve the above-described object.

  An internal combustion engine control apparatus according to the present invention is an internal combustion engine control apparatus that selectively performs either a self-sustained start or a load start when starting an internal combustion engine in which the pressure of fuel supplied to a fuel injection valve is variable. Therefore, when the self-sustained start is selected when starting the internal combustion engine, the gist is to lower the pressure of the fuel supplied to the fuel injection valve than when the load start is selected.

  According to the present invention, when the self-sustained start is selected when starting the internal combustion engine, the amount of intake air is reduced by lowering the pressure of the fuel supplied to the fuel injection valve than when selecting the load start. However, it is possible to suppress the air-fuel ratio from becoming excessively small, and to suppress the deterioration of exhaust emission.

It is a figure which shows the structural example of a hybrid vehicle provided with the control apparatus of the internal combustion engine which concerns on embodiment of this invention. It is a flowchart explaining an example of the process performed by the electronic controller when starting an internal combustion engine. It is a figure which shows an example of the injection quantity characteristic of a fuel injection valve.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 is a diagram illustrating a schematic configuration of a hybrid vehicle including a control device for an internal combustion engine according to an embodiment of the present invention. In the following embodiment, the hybrid vehicle having the configuration shown in FIG. 1 will be described as an example. However, the hybrid vehicle to which the present invention can be applied is not limited to the configuration shown in FIG.

  The internal combustion engine 12 is composed of, for example, a spark ignition engine having a throttle valve, has a variable fuel pressure device capable of changing the pressure of fuel supplied to the fuel injection valve, and burns fuel injected from the fuel injection valve To generate power. The power generated by the internal combustion engine 12 is transmitted to the carrier C of the planetary gear mechanism (single pinion planetary gear) 32. The planetary gear mechanism 32 here functions as a power distribution mechanism that distributes the power transmitted to the carrier C to the sun gear S and the ring gear R. When the power distributed from the carrier C to the ring gear R is transmitted to the drive shaft 17, the drive shaft 17 (drive wheel 18) is rotationally driven using the power of the internal combustion engine 12 to travel the vehicle. Is possible. On the other hand, the power distributed from the carrier C to the sun gear S is transmitted to the motor generator (rotating electric machine) 14 and converted into electric power generated by the power generation operation of the motor generator 14. The electric power generated by the motor generator 14 is supplied to a motor generator (rotary electric machine) 15 via inverters 22 and 23. The AC power supplied to the motor generator 15 is converted into motive power by the power running operation of the motor generator 15, and the motive power of the motor generator 15 is transmitted to the drive shaft 17 via the reduction gear 19. It is possible to drive the vehicle by rotating it. It is also possible to supply the electric power stored in the power storage device 20 such as a secondary battery to the motor generator 15 via the inverter 23, and perform the power running operation of the motor generator 15 with the power supplied from the power storage device 20. Thus, it is also possible to drive the drive shaft 17 using the power of the motor generator 15 without using the power of the internal combustion engine 12 to perform EV (Electric Vehicle) travel. In addition, the electric power stored in the power storage device 20 can be supplied to the motor generator 14 via the inverter 22, and the motor generator 14 is powered by the power supplied from the power storage device 20. It is also possible to start the internal combustion engine 12 in a stopped state using the power of the engine.

  The operating state of the internal combustion engine 12 is controlled by an engine electronic control unit (engine ECU) 40. The engine ECU 40 communicates with a hybrid electronic control unit (hybrid ECU) 60, and controls the operation of the internal combustion engine 12 by a control signal from the hybrid ECU 60 and outputs data related to the operating state of the internal combustion engine 12 to the hybrid ECU 60. The operating state of the motor generators 14 and 15 is controlled by a motor electronic control device (motor ECU) 50. The motor ECU 50 is also in communication with the hybrid ECU 60, controls the operation of the motor generators 14, 15 by a control signal from the hybrid ECU 60, and outputs data related to the operation state of the motor generators 14, 15 to the hybrid ECU 60. The hybrid ECU 60 receives a signal indicating the accelerator opening (depressed amount of the accelerator pedal) AC detected by the accelerator opening sensor 64.

  In the present embodiment, the internal combustion engine 12 is intermittently started and stopped when the vehicle travels (rotation drive of the drive shaft 17). The start / stop of the internal combustion engine 12 is controlled based on, for example, the remaining capacity SOC of the power storage device 20, and when the remaining capacity SOC of the power storage device 20 is larger than the threshold, the internal combustion engine 12 is stopped and the remaining capacity SOC of the power storage device 20 is reduced. If it is smaller than the threshold value, the internal combustion engine 12 is started. The remaining capacity SOC of the power storage device 20 can be calculated based on, for example, the current and voltage of the power storage device 20. During operation of the internal combustion engine 12, the hybrid ECU 60 sets the required torque Tdreq of the drive shaft 17 based on the accelerator opening AC, and sets the required torque Tereq of the internal combustion engine 12 and the required torques Tmg1req and Tmg2req of the motor generators 14 and 15. To do. The engine ECU 40 controls the operation of the internal combustion engine 12 so that the torque Te of the internal combustion engine 12 becomes the required torque Tereq, and the motor ECU 50 changes the torques Tmg1, Tmg2 of the motor generators 14, 15 to the required torques Tmg1req, Tmg2req. Thus, the power generation operation of the motor generator 14 and the power running operation of the motor generator 15 are controlled, and the power storage device 20 is charged with the generated power of the motor generator 14. On the other hand, when the internal combustion engine 12 is stopped, the hybrid ECU 60 sets the required torque Tdreq of the drive shaft 17 based on the accelerator opening degree AC to set the required torque Tmg2req of the motor generator 15, and the motor ECU 50 The power running operation of the motor generator 15 is controlled so that the torque Tmg2 becomes the required torque Tmg2req.

  When the internal combustion engine 12 is started, the hybrid ECU 60 selectively performs either a self-sustained start or a load start. In the self-sustained start, the internal combustion engine 12 is started with a small throttle opening so that the internal combustion engine 12 can be independently operated in an idling operation. On the other hand, in the load start, the internal combustion engine 12 is started with a large throttle opening so that the internal combustion engine 12 is loaded. The selection of the independent start or the load start is performed based on, for example, the required torque Tdreq (accelerator opening AC) of the drive shaft 17, and the required torque Tdreq (accelerator opening AC) of the drive shaft 17 is equal to or less than a set value. The self-sustained start is selected giving priority to vibration suppression, and when the required torque Tdreq (accelerator opening AC) of the drive shaft 17 is larger than the set value, the load start is selected giving priority to the vehicle acceleration performance. Hereinafter, a process executed by the hybrid ECU 60 when the internal combustion engine 12 is started will be described with reference to a flowchart of FIG.

  First, in step S101, it is determined whether it is a self-sustained start request or a load start request. When the accelerator opening degree AC is larger than the set value, the load start request is selected, and the process proceeds to step S102. On the other hand, when the accelerator opening degree AC is equal to or smaller than the set value, the self-sustained start request is selected, and the process proceeds to step S103.

  In step S102, a target fuel pressure Pireq, which is a target value of the pressure of fuel supplied to the fuel injection valve (fuel pressure in the variable fuel pressure device), is set to be higher than a predetermined value P0. A signal indicating the load start request and the target fuel pressure Pireq (Pirq> P0) is transmitted to the engine ECU 40, and the engine ECU 40 controls the variable fuel pressure device so that the pressure Pi of the fuel supplied to the fuel injection valve becomes the target fuel pressure Pireq. At the same time, the load of the internal combustion engine 12 is started with a large throttle opening.

  On the other hand, in step S103, the target fuel pressure Pireq is set lower than the predetermined value P0. A signal indicating the self-sustained start request and the target fuel pressure Pireq (Pirq <P0) is transmitted to the engine ECU 40, and the engine ECU 40 controls the variable fuel pressure device so that the pressure Pi of the fuel supplied to the fuel injection valve becomes the target fuel pressure Pireq. At the same time, the internal combustion engine 12 is started independently with a small throttle opening corresponding to idling.

In the fuel injection valve, when the solenoid is energized, the needle valve is opened and fuel is injected, and when the solenoid is de-energized, the needle valve is closed and fuel injection is stopped. FIG. 3 shows the relationship between the energization time and the fuel injection amount at a certain fuel injection pressure Pi. When the needle valve is displaced to the fully open position or the fully closed position, the needle valve hits the stopper (when fully opened) or the valve seat (when fully closed) and rebounds. Therefore, as shown in FIG. 3, in the region where the solenoid energization time is short and the needle valve opening time is short (region below Ti _{min in} FIG. 3), the linearity between the energization time and the fuel injection amount is lost. . To ensure the fuel injection accuracy, it is necessary to perform the fuel injection in the Ti _min or more energizing time, fuel injection amount q _min corresponding to energization time Ti _min corresponds to the minimum injection amount. Ti _min and q _min change according to the pressure Pi of the fuel supplied to the fuel injection valve, and decrease with a decrease in the pressure Pi.

When the self-sustained start of the internal combustion engine 12 is selected, since the throttle opening is small and the intake air amount is small, if the pressure Pi of the fuel supplied to the fuel injection valve is high, the energization time is reduced to Ti _min and the fuel injection amount Even if q is reduced to q _{min, the} fuel injection amount becomes excessive with respect to the intake air amount, and the air-fuel ratio tends to become rich (small). In contrast, in the present embodiment, when the self-sustained start is selected when the internal combustion engine 12 is started, the pressure Pi of the fuel supplied to the fuel injection valve is reduced below the predetermined value P0 and the load start is selected. Rather, the pressure Pi of the fuel supplied to the fuel injection valve is reduced. As a result, it is possible to suppress the air-fuel ratio from becoming rich even if Ti _min and q _min are decreased and the intake air amount is small. As a result, deterioration of exhaust emission can be suppressed.

  In this embodiment, when the self-sustained start of the internal combustion engine 12 is selected, when performing self-failure diagnosis (OBD) of the fuel pressure sensor that detects the pressure (pressure of fuel supplied to the fuel injection valve) Pi of the variable fuel pressure device It is also possible to change the target fuel pressure Pireq in at least two stages. For example, the target fuel pressure Pireq can be initially set lower than the predetermined value P0, then higher than the predetermined value P0, and finally lower than the predetermined value P0. Thereby, it is possible to suppress the air-fuel ratio from becoming rich while performing self-failure diagnosis of the fuel pressure sensor.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, and it can implement with a various form in the range which does not deviate from the summary of this invention. Of course.

  12 internal combustion engine, 14, 15 motor generator, 17 drive shaft, 18 drive wheel, 20 power storage device, 22, 23 inverter, 32 planetary gear mechanism, 40 engine electronic control device, 50 motor electronic control device, 60 hybrid electronic Control device, 64 accelerator opening sensor.

Claims (1)

A control device for an internal combustion engine that selectively performs either a self-sustained start or a load start when starting an internal combustion engine in which the pressure of fuel supplied to a fuel injection valve is variable,
A control device for an internal combustion engine that reduces the pressure of fuel supplied to a fuel injection valve when selecting a self-sustained start when starting the internal combustion engine than when selecting a load start.

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