JP2018100644A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine that executes cleaning treatment capable of removing deposits in a wider range of a fuel injection valve.SOLUTION: An electronic control unit 31 includes: an injection valve control section 36 for controlling a fuel injection valve 27 of an internal combustion engine 10; and a pressure control section 35 for controlling pressure of fuel to be supplied to the fuel injection valve 27. The electronic control unit 31 executes cleaning treatment for removing deposits accumulated on a tip of the fuel injection valve 27 by causing the injection valve control section 36 to inject fuel from the fuel injection valve 27 while the pressure control section 35 increases the pressure of the fuel to be supplied to the fuel injection valve 27 to predetermined pressure or higher. The electronic control unit 31 executes the cleaning treatment by causing the injection valve control section 36 to inject fuel from the fuel injection valve 27 plurality of times while the pressure control section 35 periodically fluctuates the pressure of the fuel to be supplied to the fuel injection valve 27 to the extent that the fuel pressure is not below the predetermined pressure.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for an internal combustion engine.

  In Patent Document 1, when it is determined that deposits are accumulated at the tip of the fuel injection valve, fuel is injected after increasing the pressure of the fuel supplied to the fuel injection valve, and the deposit is blown off by the injected fuel. A control device for an internal combustion engine that performs a cleaning process is disclosed.

JP 2014-152718 A

  By the way, in the control apparatus of the internal combustion engine described in Patent Document 1, there is a possibility that the deposit cannot be sufficiently removed during one cleaning process, and there is room for improvement.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
An internal combustion engine control apparatus for solving the above-described problems includes an injection valve control unit that controls a fuel injection valve of the internal combustion engine, and a pressure control unit that controls the pressure of fuel supplied to the fuel injection valve. Yes. The control device causes the injection valve control unit to inject fuel from the fuel injection valve in a state where the pressure of the fuel supplied to the fuel injection valve by the pressure control unit is increased to a predetermined pressure or higher. A cleaning process for removing deposits accumulated at the tip of the fuel injection valve is executed. Further, the control device is configured such that the fuel injector supplied by the pressure controller to the fuel injector is periodically fluctuated within a range that does not fall below the predetermined pressure. The cleaning process is performed by injecting fuel from the valve a plurality of times.

  The shape of the spray injected from the fuel injection valve, that is, the range where the fuel spray reaches the tip of the fuel injection valve varies depending on the pressure of the fuel supplied to the fuel injection valve. Therefore, when the pressure of the fuel supplied to the fuel injection valve is kept constant during the cleaning process, the deposit can be removed because the shape of the fuel spray injected from the fuel injection valve is constant. There is a risk that the location may be biased.

  On the other hand, according to the above configuration, a plurality of fuel injections performed during the execution of the cleaning process are performed while changing the pressure of the fuel supplied to the fuel injection valve. That is, during the cleaning process, fuel injection is performed a plurality of times while changing the shape of the spray. Therefore, a wider range of deposits can be removed during one cleaning process compared to a case where fuel injection is performed a plurality of times at a constant pressure during one cleaning process.

The schematic diagram which shows the relationship between the electronic control unit which is one Embodiment of the control apparatus of an internal combustion engine, and the fuel supply system of the internal combustion engine which is the control object. The flowchart which shows the flow of a series of processes concerning the cleaning process which the electronic control unit concerning the embodiment performs. The time chart which shows transition of the fuel pressure in the cleaning process which the electronic control unit concerning the embodiment performs.

Hereinafter, an embodiment in which a control device for an internal combustion engine is embodied as an electronic control unit for controlling an internal combustion engine mounted on a vehicle will be described with reference to FIGS. 1 to 3.
As shown in FIG. 1, a feed pump 12 is provided inside the fuel tank 11 of the internal combustion engine 10 to be controlled by the electronic control unit 31 of the present embodiment. The feed pump 12 pumps the fuel in the fuel tank 11 and sends it to the high pressure fuel pump 14 through the low pressure fuel passage 13. The low-pressure fuel passage 13 is opened when the pressure of the fuel flowing in the low-pressure fuel passage 13 becomes excessively high by the filter 15 for filtering foreign matters contained in the fuel, and the fuel in the low-pressure fuel passage 13 is fueled. A pressure regulator 16 that discharges into the tank 11 is provided.

  The high-pressure fuel pump 14 includes a cylinder 17, a plunger 18 disposed in the cylinder 17, and a pressurizing chamber 19 that is defined in the cylinder 17 by the plunger 18. The plunger 18 reciprocates along the cylinder 17 according to the rotation of the cam 20 provided on the camshaft 21 of the internal combustion engine 10 to change the volume of the pressurizing chamber 19.

  The low pressure fuel passage 13 is connected to a pulsation damper 22 that attenuates the pressure pulsation of the fuel accompanying the pressurizing operation of the high pressure fuel pump 14, and the pulsation damper 22 is pressurized via an electromagnetic spill valve 23. Connected to chamber 19. The electromagnetic spill valve 23 is a normally open type electromagnetic valve, which communicates the pulsation damper 22 and the pressurizing chamber 19 when the valve is opened, and blocks the communication when the valve is closed.

  The pressurizing chamber 19 in the high-pressure fuel pump 14 is connected to the high-pressure fuel passage 25 via a check valve 24 that opens when the fuel pressure inside the high-pressure fuel pump 14 exceeds a predetermined valve opening pressure. The high-pressure fuel pump 14 is connected to the high-pressure fuel pipe 26 via the high-pressure fuel passage 25.

  A fuel injection valve 27 for each cylinder of the internal combustion engine 10 is connected to the high-pressure fuel pipe 26. The internal combustion engine 10 is an internal combustion engine having four cylinders, and a total of four fuel injection valves 27 are provided for each cylinder. The fuel injection valve 27 is an electromagnetic in-cylinder fuel injection valve that injects fuel into the cylinder in response to energization. The high-pressure fuel pipe 26 has a fuel pressure sensor 28 that detects the fuel pressure Pf, which is the pressure of the fuel inside the high-pressure fuel pipe 26, and opens when the fuel pressure in the high-pressure fuel pipe 26 exceeds a predetermined relief pressure. A relief valve 29 for returning the fuel in the high-pressure fuel pipe 26 to the fuel tank 11 through the drain passage 30 is provided.

  In the internal combustion engine 10 having such a fuel supply system, the fuel pressurization operation in the high-pressure fuel pump 14 is performed in the following manner. In the following, the movement of the plunger 18 in the direction of increasing the volume of the pressurizing chamber 19 is referred to as lowering of the plunger 18, and the movement of the plunger 18 in the direction of reducing the volume of the pressurizing chamber 19 is referred to as the plunger 18. Called the rise.

  While the plunger 18 is descending, the energization of the electromagnetic spill valve 23 is stopped, and the pressurizing chamber 19 is communicated with the low pressure fuel passage 13 through the opened electromagnetic spill valve 23. When the plunger 18 is lowered in this state and the volume of the pressurizing chamber 19 is increased, the fuel pumped out from the fuel tank 11 by the feed pump 12 is sucked into the pressurizing chamber 19. When the plunger 18 changes from descending to ascending, the volume of the pressurizing chamber 19 is reduced in accordance with the ascent. At this time, if the state where the energization to the electromagnetic spill valve 23 is stopped is continued, the fuel in the pressurizing chamber 19 is returned to the low-pressure fuel passage 13 through the opened electromagnetic spill valve 23.

  On the other hand, when the energization of the electromagnetic spill valve 23 is started while the plunger 18 is moving up, the closed electromagnetic spill valve 23 cuts off the communication between the pressurizing chamber 19 and the low-pressure fuel passage 13, and the pressurizing chamber 19 is sealed. Is done. As the volume of the pressurizing chamber 19 is reduced, the fuel pressure inside the pressurizing chamber 19 increases. When the pressure of the fuel in the pressurizing chamber 19 reaches the valve opening pressure of the check valve 24, the check valve 24 is opened and the fuel in the pressurizing chamber 19 is discharged to the high pressure fuel passage 25. Then, when the plunger 18 turns from rising to lowering, the energization to the electromagnetic spill valve 23 is stopped, and the suction of the fuel in the low pressure fuel passage 13 into the pressurizing chamber 19 is started again.

  The high-pressure fuel pump 14 supplies high-pressure fuel to the high-pressure fuel pipe 26 by repeating such pressurization operation by suction and discharge of fuel. In such a high pressure fuel pump 14, when the energization start timing of the electromagnetic spill valve 23 during the ascending period of the plunger 18 is changed, the fuel discharge amount per pressurizing operation is changed.

  The electronic control unit 31 applied to the internal combustion engine 10 having the fuel supply system configured as described above includes a central processing unit that performs various arithmetic processes, a read-only memory that stores control programs and data, A readable / writable memory is provided for temporarily storing calculation results of the central processing unit and detection results of external sensors. The electronic control unit 31 also includes an input port for receiving a signal from the outside and an output port for transmitting the signal to the outside.

  In addition to the fuel pressure sensor 28 described above, detection signals from various sensors such as a crank angle sensor 32, an air flow meter 33, an accelerator position sensor 34, and a vehicle speed sensor 37 are input to the input port of the electronic control unit 31. The crank angle sensor 32 detects the rotation angle (crank angle) of the crankshaft of the internal combustion engine 10, and the air flow meter 33 detects the intake air amount of the internal combustion engine 10. The accelerator position sensor 34 detects the amount of depression of the accelerator pedal. The vehicle speed sensor 37 outputs a vehicle speed signal indicating the speed of the vehicle.

  Based on the detection results of these sensors, the electronic control unit 31 calculates the rotational speed of the crankshaft (engine speed NE), the load (engine load KL), and the like. The electronic control unit 31 controls fuel injection by controlling the fuel injection valve 27 based on the calculation result, control of the fuel pressure Pf in the high-pressure fuel pipe 26, that is, the fuel to be supplied to the fuel injection valve 27. Fuel pressure control, which is pressure control, is performed.

  Specifically, the electronic control unit 31 includes a pressure control unit 35 that performs fuel pressure control and an injection valve control unit 36 that performs fuel injection control. In the fuel pressure control, the pressure control unit 35 first calculates a target pressure Pt that is a target value of the fuel pressure Pf based on the engine load KL and the like. The target pressure Pt is basically set to a higher pressure as the fuel consumption is higher and the load is higher. Then, the pressure control unit 35 adjusts the energization start timing of the electromagnetic spill valve 23 during the ascending period of the plunger 18 according to the deviation between the fuel pressure Pf detected by the fuel pressure sensor 28 and the target pressure Pt, and the high-pressure fuel pump 14. The amount of fuel discharged is controlled. For example, when the fuel pressure Pf is lower than the target pressure Pt, the pressure control unit 35 increases the fuel discharge amount of the high-pressure fuel pump 14 by increasing the energization start timing of the electromagnetic spill valve 23. As a result, the amount of fuel supplied from the high-pressure fuel pump 14 is made larger than the amount of fuel consumed by fuel injection, and the fuel pressure Pf is increased. Further, when the fuel pressure Pf is higher than the target pressure Pt, the pressure control unit 35 delays the energization start timing of the electromagnetic spill valve 23 and decreases the fuel discharge amount of the high-pressure fuel pump 14. As a result, the amount of fuel supplied from the high-pressure fuel pump 14 is made smaller than the amount of fuel consumed by fuel injection, and the fuel pressure Pf is lowered. If the fuel injection amount of the fuel injection valve 27 continues in a steady state, the fuel pressure Pf substantially coincides with the target pressure Pt, and the amount of fuel consumed by the fuel injection and the fuel supply from the high-pressure fuel pump 14 are reduced. The quantity is in balance.

  Further, in the fuel injection control, the injection valve control unit 36 calculates a required injection amount Qt that is a required value of the fuel injection amount and an injection start timing based on the engine speed NE and the engine load KL. The injection valve control unit 36 calculates the energization time (required energization time Tt) of the fuel injection valve 27 for injecting fuel corresponding to the required injection amount Qt based on the fuel pressure Pf, and the injection start timing The fuel injection valve 27 is energized for a period until the calculated energization time elapses.

  Furthermore, the electronic control unit 31 performs a cleaning process for blowing away deposits deposited on the tip of the fuel injection valve 27 during engine operation. In the following part, this cleaning process will be described in detail with reference to FIG. 2 which is a flowchart showing a flow of a series of processes related to the cleaning process executed by the electronic control unit 31. Note that this series of processing is repeatedly executed by the electronic control unit 31 at regular control intervals when the cleaning processing is not being executed during operation of the internal combustion engine 10.

  As shown in FIG. 2, when this series of processes is started, the electronic control unit 31 determines whether or not the vehicle has traveled a predetermined distance or more from the previous cleaning process in step S100. The electronic control unit 31 integrates the travel distance of the vehicle based on the vehicle speed signal output from the vehicle speed sensor 37. In step S100, it is determined using the accumulated travel distance whether the travel distance after the previous cleaning process is equal to or greater than a predetermined distance.

  If it is determined in step S100 that the vehicle has traveled a predetermined distance or more from the previous cleaning process (step S100: YES), the process proceeds to step S200, and whether or not the electronic control unit 31 is in a high load operation. Determine. Here, the electronic control unit 31 determines that the engine is operating at a high load when the engine load KL is equal to or greater than a predetermined value.

  When it determines with it being high load driving | operation in step S200 (step S200: YES), a process is advanced to step S300 and the electronic control unit 31 performs a cleaning process.

  On the other hand, if it is determined in step S100 that the vehicle has not traveled more than a predetermined distance from the previous cleaning process (step S100: NO), or if it is determined in step S200 that it is not a high-load operation (step S200: NO). The electronic control unit 31 once ends this series of processes. That is, the electronic control unit 31 executes the cleaning process on the condition that the vehicle has traveled a predetermined distance or more from the previous cleaning process and is a high-load operation.

  As shown in FIG. 3, when performing the cleaning process, first, the range set by the pressure control unit 35 in the electronic control unit 31 in the normal fuel pressure control not performing the cleaning process (FIG. 3). The fuel pressure Pf is increased to a predetermined pressure Py that is higher than the highest pressure Px in the hatched area in FIG. Specifically, the target pressure Pt is set to a value equal to or higher than the predetermined pressure Py, and the fuel pressure Pf is increased to the predetermined pressure Py or higher. The predetermined pressure Py is a pressure equal to or higher than the lower limit value of the pressure at which deposits accumulated at the tip of the fuel injection valve 27 can be blown off and removed by injecting fuel from the fuel injection valve 27.

  Then, as shown in FIG. 3, the pressure control unit 35 periodically varies the fuel pressure Pf within a range that does not fall below the predetermined pressure Py. At this time, the fluctuation cycle Tc of the fuel pressure Pf is preferably several seconds, and here, the fluctuation cycle Tc is set to “2 seconds”. The amplitude of the fluctuation of the fuel pressure Pf is set in a range where the fuel pressure Pf does not fall below the predetermined pressure Py and does not exceed the relief pressure.

  In this way, the injection valve control unit 36 injects fuel from the fuel injection valve 27 in a state where the pressure of the fuel supplied to the fuel injection valve 27 by the pressure control unit 35 is periodically varied within a range not lower than the predetermined pressure Py. Thus, the cleaning process is executed.

  At this time, since the fuel pressure Pf is higher than the range set in the normal fuel pressure control, the injection valve control unit 36 sets the energization time to the fuel injection valve 27 to the normal time when the cleaning process is not performed. By making it shorter than in the case of the fuel injection control, it is possible to prevent the fuel injection amount from becoming excessively large. Further, since the fuel pressure Pf periodically varies, even when the required injection amount Qt is equal, the injection valve control unit 36 sets the energization time in accordance with the value of the fuel pressure Pf when performing fuel injection. adjust.

  The electronic control unit 31 performs the cleaning process for injecting fuel from the fuel injection valve 27 in a state where the fuel pressure Pf is periodically changed within a range not lower than the predetermined pressure Py in this way, corresponding to several times the change cycle Tc. The cleaning process is terminated by continuing the period of time, for example, “6 seconds” corresponding to three times the fluctuation period Tc. When the cleaning process ends, the electronic control unit 31 performs normal fuel pressure control and fuel injection control.

  As described above, when the cleaning process is performed for 6 seconds, if the engine speed NE during the cleaning process is constant at 3000 [rpm], the cleaning process is performed during the cleaning process. The fuel injection is executed 150 times from each fuel injection valve 27.

Next, operations and effects of the electronic control unit 31 according to the present embodiment will be described.
The shape of the fuel spray injected from the fuel injection valve 27, that is, the range where the fuel spray reaches the tip of the fuel injection valve 27 varies depending on the pressure of the fuel supplied to the fuel injection valve 27. Therefore, when the pressure of the fuel supplied to the fuel injection valve 27 is kept constant during the cleaning process, the shape of the fuel spray injected from the fuel injection valve 27 is constant, so the deposit is reduced. There may be a bias in the places where removal is possible.

  On the other hand, according to the electronic control unit 31 described above, a plurality of fuel injections performed during the execution of the cleaning process are performed while changing the pressure of the fuel supplied to the fuel injection valve 27. That is, during the cleaning process, fuel injection is performed a plurality of times while changing the shape of the spray. Therefore, a wider range of deposits can be removed during one cleaning process compared to a case where fuel injection is performed a plurality of times at a constant pressure during one cleaning process.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the cleaning process, the extent to which the fuel pressure Pf is increased may be appropriately set according to the characteristics of the fuel injection valve 27 and the like. Further, the magnitude of the amplitude of the fuel pressure Pf during the execution of the cleaning process may be appropriately set according to the characteristics of the fuel injection valve 27 and the like.

Although the example in which the length of the fluctuation cycle Tc of the fuel pressure Pf in the cleaning process is set to “2 seconds” is shown, the length of the fluctuation cycle Tc may be set as appropriate in accordance with the characteristics of the fuel injection valve 27 and the like.
・ The duration of the cleaning process can be changed as appropriate. Although an example in which “6 seconds” corresponding to three times the fluctuation cycle Tc is set is shown, it is not always necessary to set the duration of the cleaning process in accordance with the length of the fluctuation cycle Tc. It may be set to “5 seconds”. Further, the duration of the cleaning process may be set according to conditions such as the number of times of fuel injection from each fuel injection valve 27 reaches a predetermined number.

  -The execution conditions of the cleaning process can be changed as appropriate. For example, the cleaning process is not limited to during high-load operation. However, since it is necessary to perform fuel injection in a state where the fuel pressure Pf is increased in the cleaning process, from the viewpoint of smooth transition to the cleaning process and control of energization to the fuel injection valve 27, the fuel pressure Pf is originally It is preferable to execute the cleaning process at the time of high load operation which becomes high. Moreover, you may make it perform a cleaning process irrespective of the length of the travel distance from the last cleaning process.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 11 ... Fuel tank, 12 ... Feed pump, 13 ... Low pressure fuel passage, 14 ... High pressure fuel pump, 15 ... Filter, 16 ... Pressure regulator, 17 ... Cylinder, 18 ... Plunger, 19 ... Pressure chamber, DESCRIPTION OF SYMBOLS 20 ... Cam, 21 ... Cam shaft, 22 ... Pulsation damper, 23 ... Electromagnetic spill valve, 24 ... Check valve, 25 ... High pressure fuel passage, 26 ... High pressure fuel piping, 27 ... Fuel injection valve, 28 ... Fuel pressure sensor, 29 DESCRIPTION OF SYMBOLS ... Relief valve, 30 ... Drain passage, 31 ... Electronic control unit, 32 ... Crank angle sensor, 33 ... Air flow meter, 34 ... Accelerator position sensor, 35 ... Pressure control part, 36 ... Injection valve control part, 37 ... Vehicle speed sensor.

Claims (1)

An injection valve controller for controlling a fuel injection valve of the internal combustion engine;
A pressure control unit for controlling the pressure of the fuel supplied to the fuel injection valve,
In a state where the pressure of the fuel supplied to the fuel injection valve by the pressure control unit is increased to a predetermined pressure or more, the injection valve control unit injects fuel from the fuel injection valve, thereby leading the tip of the fuel injection valve A control device for an internal combustion engine that executes a cleaning process to remove deposits accumulated in
In the state where the pressure of the fuel supplied to the fuel injection valve by the pressure control unit is periodically changed within a range not lower than the predetermined pressure, the injection valve control unit injects fuel from the fuel injection valve a plurality of times. A control device for an internal combustion engine that executes the cleaning process.

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