JP6435984B2 - Control device for internal combustion engine - Google Patents

Description

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

  Determine whether the combustion state of an engine that can use CNG and gasoline as fuel is normal or abnormal based on the air-fuel ratio feedback amount before and after fuel switching, and identify the abnormal part of the engine from both determination results Has been proposed (see, for example, Patent Document 1).

International Publication No. 2014/136387 JP 2013-224649 A

  In a stand that fills a vehicle with gas fuel such as CNG, compressor oil (hereinafter simply referred to as oil) may be mixed into the gas fuel tank in the vehicle because the gas fuel is pressurized with a compressor. Therefore, in an engine that can use gas fuel and gasoline as fuel, the oil mixed in the gas fuel may flow into the injector, causing the injector to become clogged.

  Accordingly, an object of the present invention is to provide an internal combustion engine control device capable of suppressing clogging of a fuel injection valve for gas fuel in an internal combustion engine provided with a fuel injection valve for gasoline and a fuel injection valve for gas fuel. It is in.

In order to solve the above problems, a control device for an internal combustion engine comprising the fuel injection valve for gasoline and the fuel injection valve for gas fuel and an air-fuel ratio sensor disposed in an exhaust system according to the present invention is provided. The difference between the target air-fuel ratio and the actual air-fuel ratio detected by the air-fuel ratio sensor when gas fuel is supplied without supplying gasoline to the engine exceeds the first specified value, and gas fuel is supplied to the internal combustion engine Detecting means for detecting that the difference between the target air-fuel ratio and the actual air-fuel ratio detected by the air-fuel ratio sensor when gasoline is supplied without exceeding a second specified value; and When it is detected that the state has been detected, warning means for issuing a warning that oil has been mixed into the gas fuel; and after the detection of the state has been detected by the detection means , supply the gas fuel. Without scorpion In gasoline during operation is a case that supplies, when the gasoline supply to the internal combustion engine is stopped during the rotation of the crankshaft of the internal combustion engine, by idle striking the gas fuel for the fuel injection valve Scavenging means for scavenging the fuel injection valve for gas fuel.

  According to the present invention, since the fuel injection valve for gas fuel is idled, clogging of the fuel injection valve for gas fuel can be suppressed. Further, according to the present invention, it is possible to notify the user that oil has been mixed into the gas fuel.

FIG. 1 is a schematic configuration diagram of an internal combustion engine system to which a control device for an internal combustion engine according to a first embodiment of the present invention is applied. FIG. 2A is a flowchart of an oil mixing detection process performed by the ECU as the control device for the internal combustion engine according to the first embodiment. FIG. 2B is a flowchart of an oil mixture handling process performed by the ECU as the control device for the internal combustion engine according to the first embodiment. FIG. 3 is an explanatory diagram of the contents of the oil mixture detection process and the oil mixture handling process performed by the ECU as the control device for the internal combustion engine according to the first embodiment. FIG. 4 is a flowchart of an oil contamination detection process performed by the ECU as the control device for the internal combustion engine according to the second embodiment. FIG. 5 is an explanatory diagram of the contents of the oil mixture detection process and the oil mixture handling process performed by the ECU as the control device for the internal combustion engine according to the second embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

<< First Embodiment >>
FIG. 1 shows a schematic configuration of an internal combustion engine system to which an internal combustion engine control apparatus according to a first embodiment of the present invention is applied.

  First, the configuration of the internal combustion engine system shown in FIG. 1 will be described. This internal combustion engine system is a system mounted on a vehicle. As shown, the internal combustion engine system includes an internal combustion engine 10, a gasoline tank 20, a CNG tank 30, an ECU (Electronic Control Unit) 40 as a control device for the internal combustion engine according to the first embodiment, and the like.

  The internal combustion engine 10 is a four-cylinder internal combustion engine in which a spark plug 11 is attached to each cylinder. Each intake port 10a of the internal combustion engine 10 is provided with a gasoline injector 25 for injecting the gasoline in the gasoline tank 20 sent by the feed pump 21 into the intake port 10a.

  Each intake port 10 a of the internal combustion engine 10 is connected to an intake passage 15 via an intake manifold (hereinafter also referred to as intake manifold) 13. In the intake passage 15, an air cleaner 41, an air amount sensor 51, and a throttle valve 42 are arranged in this order from the upstream side.

  A temperature sensor 52 for detecting the temperature of the intake manifold 13 and a pressure sensor 53 for detecting the pressure in the intake manifold 13 are attached to the intake manifold 13. Each branch pipe 13a of the intake manifold 13 is provided with a CNG injector 35 that injects CNG from the CNG tank 30 toward the intake port 10a.

  Each CNG injector 35 is connected to the CNG tank 30 via a CNG delivery 32 and a gas pipe 31. A regulator 33 for adjusting the pressure of CNG supplied to the CNG delivery 32 is disposed in the middle of the gas pipe 31. The regulator 33 includes a CNG cutoff valve for blocking the supply of CNG to the CNG delivery 32 side, and an oil filter for removing oil from the CNG passing through the regulator 33.

  A pressure sensor 54 and a temperature sensor 55 for measuring the pressure and temperature of the CNG in the gas pipe 31 are provided on the upstream side (CNG tank 30 side) of the gas pipe 31 from the regulator 13, respectively. .

An exhaust passage 18 is connected to each exhaust port (not shown) of the internal combustion engine 10 via an exhaust manifold (hereinafter also referred to as an exhaust manifold) 17. An air-fuel ratio sensor 56 for detecting an air-fuel ratio (A / F) is provided in the collector portion 17 a of the exhaust manifold 17. A catalyst 44 for purifying the exhaust gas of the internal combustion engine 10 is provided in the middle of the exhaust passage 18.

The ECU 40 is a unit that integrally controls each part (injectors 25, 26, etc.) of the internal combustion engine system based on signals from the sensors 51 to 56, the accelerator opening sensor 58, and the like. The ECU 40 is composed of a CPU (Central Processing Unit), a ROM (Read Only Memory; in this embodiment, a flash ROM), a RAM (Random Access Memory), and the like. Firmware) is stored. The ECU 40 is also electrically connected to an engine warning light 46, an oil overflow warning light 47 and the like provided on an instrument panel of a vehicle on which the internal combustion engine system is mounted. 47 are also controlled.

  Hereinafter, the function of the ECU 40 will be specifically described.

  The ECU 40 is basically a unit that performs air-fuel ratio feedback control in which the air-fuel ratio detected by the air-fuel ratio sensor 56 (hereinafter also referred to as an actual air-fuel ratio) is set as a target air-fuel ratio while switching fuel depending on the situation. It is. The “situation” indicates whether the warm-up is completed, whether the user (driver) desires gasoline operation, and whether the required load is a load capable of CNG operation (low / medium load). This is the situation.

  However, the ECU 40 is configured (programmed) to repeat the oil mixture detection process of the procedure shown in FIG. 2A during CNG operation.

  The ECU 40 that has started the execution of the oil mixture detection process first detects the fluctuation width ΔAF of the air-fuel ratio sensor 56 in a steady state, as shown (step S101). Note that the steady state is a period (time period) in which the amount of time change of the target air-fuel ratio is equal to or less than a predetermined change amount threshold. The fluctuation width ΔAF of the air-fuel ratio sensor 56 is the fluctuation width of the output of the air-fuel ratio sensor 56 (a value indicating the actual air-fuel ratio).

  Thereafter, the ECU 40 determines whether or not the detected fluctuation width ΔAF exceeds the first specified value (step S102). Here, the first specified value is that when the fluctuation width ΔAF is larger than that value, the oil flows into the CNG injector 35, and as a result, the oil is supplied into the cylinder (or the air-fuel ratio sensor 56). And / or a value that is set in advance (for example, 1.0) so that it can be determined that some failure has occurred in the ECU 40.

  As already described, the ECU 40 is a unit that performs air-fuel ratio feedback control in which the actual air-fuel ratio is the target air-fuel ratio. Therefore, the air-fuel ratio with the larger value that defines the fluctuation width ΔAF is normally substantially equal to the target air-fuel ratio. Therefore, whether or not the difference between the target air-fuel ratio and the actual air-fuel ratio detected by the air-fuel ratio sensor 56 when the CNG is supplied without supplying gasoline to the internal combustion engine 10 exceeds the first specified value in the determination of the above contents. It will be possible to judge whether or not.

  When the shake width ΔAF does not exceed the first specified value (step S102; NO), the ECU 40 ends the oil mixture detection process.

  On the other hand, if the swing width ΔAF exceeds the first specified value (step S102; YES), the ECU 40 starts the oil mixing handling process of the procedure shown in FIG. S110) is performed. That is, in this step S110, the ECU 40 performs a process for changing the fuel supplied to the internal combustion engine 10 from CNG to gasoline.

  Although not shown in the flowchart (FIG. 2A), the ECU 40 satisfies the condition for switching to gasoline operation different from “ΔAF> first specified value” during execution of the oil mixture detection process described above. If it is performed (when the user requests gasoline operation, when the required load becomes high load, etc.), the oil mixture detection process is terminated and the gasoline operation of the internal combustion engine 10 is started.

  In step S110, the ECU 40 also performs a process of waiting for the elapse of a predetermined time. Here, the predetermined time is a predetermined time as a time required for the fluctuation width ΔAF to be stabilized after the fuel is switched from CNG to gasoline.

  Then, the ECU 40 waiting for the elapse of the predetermined time ends the process of step S110 and detects the fluctuation width ΔAF of the air-fuel ratio sensor 56 in the steady state (step S111).

  Next, the ECU 40 determines whether or not the detected fluctuation width ΔAF exceeds the second specified value (step S112). Here, the second specified value is a value set in advance so that it can be determined that some failure has occurred in the air-fuel ratio sensor 56 and / or the ECU 40 when the fluctuation width ΔAF is larger than that value. . The second specified value may be the same value as the first specified value described above.

  When the deflection width ΔAF exceeds the second specified value (step S112; YES), the ECU 40 turns on the engine warning lamp 46 (step S113), and then ends the oil mixture handling process.

  That is, when the swing range ΔAF during CNG operation exceeds the first specified value (FIG. 2A: step S102; YES), and the swing range ΔAF during gasoline operation exceeds the second specified value (FIG. 2B: step) S112; YES), it can be determined that some failure has occurred in the air-fuel ratio sensor 56 and / or the ECU 40. Therefore, in this case, the engine warning lamp 46 is turned on to notify the user (driver) that repair is necessary.

  Hereinafter, the control content of the ECU 40 when the deflection width ΔAF is equal to or smaller than the second specified value (step S112; NO) will be described with reference to FIG.

  When the swing width ΔAF is equal to or smaller than the second specified value (step S112; NO), the ECU 40 performs a process of turning on the oil overflow warning lamp 47 and a process of prohibiting the CNG operation in step S114. Further, in step S114, the ECU 40 also performs a process of closing the CNG cutoff valve of the regulator 33 in order to enable the CNG injector to be idled in step S115 described later.

  That is, as schematically shown in FIG. 3A, the amplitude ΔAF during CNG operation exceeds the first specified value, and the amplitude ΔAF after switching to gasoline operation is less than the second specified value. In some cases, it can be determined that the oil filter of the regulator 33 overflows and the oil flows into the CNG injector 35. Therefore, by turning on the oil overflow warning lamp 46, as shown in FIG. 3B, the user is informed that oil has entered the CNG (the oil has overflowed from the oil filter, the oil in the oil filter Is issued). Further, it is not preferable that the CNG operation is performed in a state where the oil cannot be removed by the oil filter. Therefore, a process for prohibiting CNG operation (a process for storing that CNG operation is prohibited) is also performed.

The ECU 40 that has finished the process of step S114 (FIG. 2B), when the gasoline supply to the internal combustion engine 10 is stopped during the rotation of the crankshaft of the internal combustion engine 10 in step S115 (in FIG. At time “), the CNG injector 35 is scavenged by blanking the CNG injector 35.

  Specifically, in step S115, the ECU 40 waits (monitors) that fuel cut is started by another process being executed. When the fuel cut is started, the ECU 40 performs CNG only for a time (for example, a time corresponding to 5 cycles) set in advance as a time during which the dead volume from the CNG cutoff valve of the regulator 33 to each CNG injector 35 can be blown out. The injector 35 is idled (see FIGS. 3B and 3C).

  Then, the ECU 40 that has completed the above-described idle shot ends the process of step S115 and the oil mixture handling process (the process of FIG. 2B).

  As described above, when the ECU 40 supplies CNG without supplying gasoline to the internal combustion engine 10, the ΔAF exceeds the first specified value, and when gasoline is supplied without supplying CNG to the internal combustion engine 10. When it is detected that ΔAF has not exceeded the second specified value (step S102; YES, S112; NO), a warning that oil has mixed into CNG is issued (step S114). In addition, when the gasoline supply to the internal combustion engine 10 is subsequently stopped while the crankshaft of the internal combustion engine 10 is rotating, the ECU 40 idles the CNG injector 35 (step S115), thereby causing the CNG injector 35 to To scavenge.

  Therefore, according to the ECU 40, the clogging of the CNG injector 35 can be suppressed, and the user can be notified that oil has mixed into the CNG.

<< Second Embodiment >>
Hereinafter, the ECU 40 as the control device for the internal combustion engine according to the second embodiment of the present invention is used as the control device for the internal combustion engine according to the first embodiment using the same reference numerals as those used in the description of the first embodiment. A description will be given centering on differences from the ECU 40. Hereinafter, the ECU 40 as the control device for the internal combustion engine according to the first and second embodiments will be referred to as a first ECU 2 and a second ECU 40, respectively.

  The second ECU 40 replaces the oil mixture detection process (FIG. 2A; hereinafter also referred to as the first oil mixture detection process) with the oil mixture detection process (hereinafter, the second oil mixture detection process) shown in FIG. This is a unit obtained by modifying the first ECU 40 so as to execute.

  The process of step S201 of the second oil mixture detection process is the same as the process of step S101 of the first oil mixture detection process (FIG. 2A).

  In the subsequent step S202, the number of times “ΔAF> first specified value” per unit time (for example, 3000 cycles) is not a threshold value, but whether or not “ΔAF> first specified value” is satisfied. It is determined whether (for example, 10) is exceeded.

  Then, when the number of times “ΔAF> first specified value” per unit time does not exceed the threshold value (step S202; NO), the second ECU 40 ends the second oil mixture detection process. In addition, when the number of times “ΔAF> first specified value” per unit time exceeds the threshold value (step S202; YES), the second ECU 40 performs the oil mixing response process (the same content as described above) Perform FIG. 2B).

In the first oil mixture detection process for determining whether or not the oil flows into the CNG injector 35 based on whether or not “ΔAF> first specified value” is satisfied, the output of the air-fuel ratio sensor 56 is temporarily set. It is conceivable that an erroneous determination is made when a large noise appears in On the other hand, if it is determined whether or not the oil flows into the CNG injector 35 based on whether or not the number of times “ΔAF> first specified value” per unit time exceeds the threshold, FIG. It is possible to determine that oil has mixed into CNG only when the situation shown in FIG. Therefore, according to the second ECU 40, it is possible to notify the user that oil has been mixed into the CNG with almost no erroneous determination.

<Deformation>
The above-described technique can perform various modifications. For example, the ECU 40 according to each embodiment may be modified into a unit that performs the same determination as described above when switching from gasoline operation to CNG operation. Further, the oil mixture handling process (FIG. 2B) may be modified to a process of notifying the user by voice that oil has been mixed. In addition, the internal combustion engine 10 controlled by the ECU 40 includes an internal combustion engine in which the attachment positions of the injectors 25 and 35 are different from those described above, an internal combustion engine in which no oil filter is provided in the CNG supply system, and a non-CNG gas fuel ( For example, it may be an internal combustion engine in which hydrogen is used, a ship internal combustion engine, or the like.

DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine 10a ... Intake port 11 ... Spark plug 13 ... Intake manifold 13a ... Branch pipe 15 ... Intake passage 17 ... Exhaust manifold 17a ... Collector part 18.・ ・ Exhaust passage 20 ... Gasoline tank 21 ... Feed pump 25 ... Injector for gasoline 30 ... CNG tank 31 ... Gas piping 32 ... Delivery for CNG 33 ... Regulator 35 ...・ Injector for CNG 40 ... ECU
41 ... Air cleaner 42 ... Throttle valve 44 ... Catalyst 46 ... Engine warning light 47 ... Oil overflow warning light 51 ... Air volume sensor 52,55 ... Temperature sensor 53,54 ..Pressure sensor 56 ... Air-fuel ratio sensor 58 ... Accelerator opening sensor

Claims (1)

In a control device for an internal combustion engine comprising a fuel injection valve for gasoline and a fuel injection valve for gas fuel, and an air-fuel ratio sensor disposed in an exhaust system,
The difference between the target air-fuel ratio and the actual air-fuel ratio detected by the air-fuel ratio sensor when gas fuel is supplied without supplying gasoline to the internal combustion engine exceeds a first specified value, and gas is supplied to the internal combustion engine. Detecting means for detecting that the difference between the target air-fuel ratio and the actual air-fuel ratio detected by the air-fuel ratio sensor when gasoline is supplied without supplying fuel does not exceed a second specified value;
Warning means for issuing a warning that oil has mixed into the gas fuel when the detection means detects that the state has been reached;
The gasoline supply to the internal combustion engine is a crank of the internal combustion engine during gasoline operation, in which gasoline is supplied without supplying gas fuel after the detection means detects that the state has been reached. Scavenging means for scavenging the fuel injection valve for gas fuel by blanking the fuel injection valve for gas fuel when stopped during rotation of the shaft;
An internal combustion engine control device comprising:

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