JP6624085B2 - Engine equipment - Google Patents

Description

  The present invention relates to an engine device, and more particularly, to an engine device including an engine having a purification device that purifies exhaust gas.

  Conventionally, as this type of engine device, there has been proposed an engine device provided with an air-fuel ratio sensor at a subsequent stage of a purifying device for purifying exhaust gas, and controlling a fuel injection amount based on an air-fuel ratio of exhaust gas from the purifying device (for example, Patent Document 1). In this device, when the air-fuel ratio detected by the air-fuel ratio sensor is rich with respect to the stoichiometric air-fuel ratio, the fuel injection amount is corrected to the lean side, and when the air-fuel ratio is lean, the fuel injection amount is corrected to the rich side. Emission deterioration is suppressed.

JP 2014-15921 A

  When the engine is operated with the air-fuel ratio corrected to the rich side, the purifier becomes richer, and when the exhaust gas from the purifier becomes richer, unburned fuel (HC) and carbon monoxide (CO) are discharged from the purifier. Therefore, the air-fuel ratio is corrected to the lean side in order to suppress the deterioration of the emission. When the air-fuel ratio is corrected to the lean side and the engine is operated, the purifier becomes leaner, and when the exhaust gas from the purifier becomes leaner, nitrogen oxides (NOx) are discharged from the purifier. The air-fuel ratio is corrected to the rich side in order to suppress the air-fuel ratio. When the catalyst atmosphere becomes rich, the unburned fuel (HC) and carbon monoxide (CO) in the exhaust gas increase, but the unburned fuel (HC) and carbon monoxide (CO) increase with respect to the degree of richness of the catalyst atmosphere. (Gradient) is relatively gentle. On the other hand, when the catalyst atmosphere becomes lean, the nitrogen oxides (NOx) in the exhaust gas increase. However, the degree of increase (slope) of the nitrogen oxides (NOx) with respect to the degree of leanness of the catalyst atmosphere increases with the slope on the rich side. This is relatively steep. For this reason, by controlling between the stoichiometric air-fuel ratio (stoichiometric) and a little rich, the emission of unburned fuel (HC), carbon monoxide (CO), and nitrogen oxide (NOx) can be favorably suppressed. it can. For this reason, the air-fuel ratio is corrected to a slightly rich side and the engine is operated. When the exhaust gas from the purifying device becomes equal to or more than the threshold value on the slightly-closed side, the air-fuel ratio is corrected to a slightly lean side. It is also considered to correct the air-fuel ratio to a slightly rich side before the exhaust gas from the device reaches a slightly lean threshold. If such air-fuel ratio control is continued, it becomes rich up to the rear of the catalyst, so the number of times that the exhaust gas from the purification device becomes slightly richer or more than a threshold value is counted, and when the count reaches a predetermined value, It has also been considered that the fuel is cut so that the exhaust gas from the purification device is temporarily on the lean side. The count value is reset to 0 when the operation of the engine is stopped. However, in the case of an engine device mounted on a vehicle that performs an idle stop or a hybrid vehicle that performs an intermittent operation of the engine, the count value of the engine is frequently reduced. Since the start and stop are repeated and the count value is reset, the air-fuel ratio of the exhaust gas from the purification device is always on the rich side, and the emission may deteriorate.

  On the other hand, if the temperature of the catalyst in the purifying device increases, the deterioration of the catalyst proceeds. Therefore, it is also proposed to execute a catalyst deterioration suppression control for inhibiting the fuel cut from the necessity of suppressing the deterioration of the catalyst. When the fuel cut is performed such that the exhaust gas from the purification device temporarily becomes lean when the count number obtained by counting the number of times that the exhaust gas from the purification device has exceeded the threshold value on the rich side has reached a predetermined value. When the temperature of the catalyst increases, the catalyst deterioration suppression control may be executed. In this case, since the fuel cut is prohibited, the purification device cannot be once reset to the lean side.

  The main object of the engine device of the present invention is to achieve both suppression of deterioration of emission and suppression of deterioration of a catalyst of a purification device.

  The engine device of the present invention employs the following means to achieve the above-described main object.

The engine device of the present invention
An engine having a purification device for purifying exhaust gas;
An air-fuel ratio sensor that detects an air-fuel ratio at a later stage of the purification device,
A rich correction process for richly correcting the air-fuel ratio until the air-fuel ratio detected by the air-fuel ratio sensor becomes equal to or less than a rich-side threshold; and when the air-fuel ratio detected by the air-fuel ratio sensor becomes equal to or less than the rich-side threshold. And a fuel cut-off process for repeating a lean correction process of lean-correcting the air-fuel ratio over a predetermined period, and a fuel cut-off to suppress catalyst deterioration when the catalyst temperature of the purifier is equal to or higher than a catalyst temperature threshold. A control device for executing catalyst deterioration suppression control for inhibiting
An in-vehicle engine device comprising:
The control device includes:
The air-fuel ratio counter is counted up when the air-fuel ratio detected by the air-fuel ratio sensor is equal to or less than the rich side threshold, and the air-fuel ratio counter is held while the engine is stopped due to intermittent operation. When the integrated value of the intake air amount in a state where the air-fuel ratio detected by the air-fuel ratio sensor is equal to or greater than the lean side threshold value is equal to or greater than a predetermined air amount, a counter process for resetting the air-fuel ratio counter to a value of 0 is performed,
Requesting a fuel cut when the air-fuel ratio counter is equal to or greater than a predetermined count value, and setting a second temperature higher than a first temperature when the air-fuel ratio counter is less than the predetermined count value as the catalyst temperature threshold value;
That is the gist.

  In the engine device of the present invention, the rich correction process of richly correcting the air-fuel ratio until the air-fuel ratio detected by the air-fuel ratio sensor becomes equal to or less than the rich threshold, and the air-fuel ratio detected by the air-fuel ratio sensor becomes equal to or less than the rich threshold. When this happens, the fuel injection control that repeats the lean correction processing for lean-correcting the air-fuel ratio for a predetermined period is executed. As the predetermined period, a period in which oxygen stored in the purification device (oxygen storage amount) becomes equal to or more than a predetermined value after the start of the lean correction can be used. On the other hand, when the catalyst temperature of the purifying device is equal to or higher than the catalyst temperature threshold value, a catalyst deterioration suppression control for prohibiting fuel cut is executed in order to suppress catalyst deterioration. The air-fuel ratio counter is counted up when the air-fuel ratio detected by the air-fuel ratio sensor becomes equal to or less than the rich side threshold, and the air-fuel ratio counter is held while the operation is stopped due to the intermittent operation of the engine. When the integrated value of the intake air amount in the state where the air-fuel ratio detected by the above is equal to or more than the lean side threshold value becomes equal to or more than the predetermined air amount, the air-fuel ratio counter is reset to zero. Then, when the air-fuel ratio counter is equal to or more than the predetermined count value, the fuel cut is requested, and the second temperature higher than the first temperature when the air-fuel ratio counter is less than the predetermined count value is set as the catalyst temperature threshold value. Since the air-fuel ratio counter is held during the intermittent operation of the engine, the air-fuel ratio of the exhaust gas from the purification device is always maintained based on the fact that the air-fuel ratio counter is reset to 0 by the intermittent operation of the engine. On the rich side, it is possible to avoid the disadvantage that the emission deteriorates. Further, when the air-fuel ratio counter becomes equal to or more than a predetermined count value and requests a fuel cut in order to temporarily set the purifier to the lean side, the catalyst temperature threshold is set to a second temperature higher than the normal first temperature. The execution of the catalyst deterioration suppression control (prohibition of fuel cut) is suppressed. For this reason, the execution condition of the fuel cut is easily satisfied, and the opportunity of executing the fuel cut increases. As a result, it is possible to achieve both suppression of deterioration of emission and suppression of deterioration of the catalyst of the purification device. Here, the intermittent operation of the engine includes idle stop.

1 is a configuration diagram schematically illustrating a configuration of a hybrid vehicle 20 equipped with an engine device as an embodiment of the present invention. FIG. 2 is a configuration diagram schematically illustrating configurations of an engine 22 and a fuel supply device 60 as an engine device. 4 is a flowchart illustrating an example of a fuel injection amount correction processing routine executed by an engine ECU 24. FIG. 5 is an explanatory diagram showing an example of a time change of an air-fuel ratio AF2, fuel correction and emission when a fuel injection amount correction processing routine of the embodiment is repeatedly executed. 4 is a flowchart illustrating an example of a catalyst adjustment processing routine executed by an engine ECU 24. 4 is a flowchart illustrating an example of a lean-time integrated air amount calculation processing routine executed by an engine ECU 24. 5 is a flowchart illustrating an example of a rich accumulated air amount calculation processing routine executed by an engine ECU 24. 5 is a flowchart illustrating an example of a counter processing routine executed by the engine ECU 24.

  Next, an embodiment for carrying out the present invention will be described using an embodiment.

  FIG. 1 is a configuration diagram schematically illustrating a configuration of a hybrid vehicle 20 equipped with an engine device as an embodiment of the present invention, and FIG. 2 is a schematic diagram illustrating configurations of an engine 22 and a fuel supply device 60 as an engine device. FIG. As shown in FIG. 1, the hybrid vehicle 20 of the embodiment includes an engine 22, a fuel supply device 60, a planetary gear 30, motors MG1 and MG2, inverters 41 and 42, a battery 50, and a hybrid electronic control unit. (Hereinafter, referred to as “HVECU”) 70.

  The engine 22 is configured as an internal combustion engine that outputs power using fuel such as gasoline or light oil. As shown in FIG. 2, the engine 22 has a port injection valve 125 that injects fuel into an intake port, and an in-cylinder injection valve 126 that injects fuel into a cylinder. Since the engine 22 has the port injection valve 125 and the in-cylinder injection valve 126, it can be operated in any of the port injection mode, the in-cylinder injection mode, and the common injection mode. In the port injection mode, the air cleaned by the air cleaner 122 is sucked in through the throttle valve 124 and the fuel is injected from the port injection valve 125 to mix the air and the fuel. Then, the air-fuel mixture is sucked into the combustion chamber via the intake valve 128, explosively burned by the electric spark of the ignition plug 130, and the reciprocating motion of the piston 132 pushed down by the energy is converted into the rotational motion of the crankshaft 26. . In the in-cylinder injection mode, as in the port injection mode, air is sucked into the combustion chamber, fuel is injected from the in-cylinder injection valve 126 during the intake stroke or after reaching the compression stroke, and explosive combustion is caused by an electric spark generated by the ignition plug 130. Thus, the rotational movement of the crankshaft 26 is obtained. In the common injection mode, when air is sucked into the combustion chamber, fuel is injected from the port injection valve 125 and fuel is injected from the in-cylinder injection valve 126 during the intake stroke and the compression stroke. Thus, the rotational movement of the crankshaft 26 is obtained. These injection modes are switched based on the operating state of the engine 22. Exhaust gas from the combustion chamber is discharged to the outside air via a purifying device 134 having a purifying catalyst (three-way catalyst) for purifying harmful components such as carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx). Is done.

  As shown in FIG. 2, the fuel supply device 60 is configured as a device that supplies fuel to the port injection valve 125 and the in-cylinder injection valve 126 of the engine 22. The fuel supply device 60 includes a fuel tank 61, a feed pump (first pump) 62 that supplies fuel from the fuel tank 61 to a low-pressure side passage (first passage) 63 to which the port injection valve 125 is connected, and a low-pressure side passage. A check valve 64 provided in 63 and a high-pressure side passage (second passage) to which the fuel in the port injection valve 125 side with respect to the check valve 64 in the low-pressure side passage 63 is pressurized and the in-cylinder injection valve 126 is connected. And a high-pressure fuel pump (second pump) 65 that supplies the fuel to the fuel pump 66.

  The feed pump 62 and the check valve 64 are arranged in the fuel tank 61. The feed pump 62 is configured as an electric pump that operates by receiving supply of electric power from the battery 50. The check valve 64 is opened when the fuel pressure (fuel pressure) on the side of the feed pump 62 in the low pressure side passage 63 is higher than the fuel pressure on the side of the port injection valve 125, and the pressure on the side of the feed pump 62 is reduced toward the port injection valve 125. The valve is closed when the fuel pressure is equal to or lower than.

  The high-pressure fuel pump 65 is a pump driven by the power (rotation of the camshaft) from the engine 22 to pressurize the fuel in the low-pressure side passage 63. The high-pressure fuel pump 65 is connected to its suction port and opens and closes when fuel is pressurized, and is connected to its discharge port to prevent backflow of fuel and maintain the fuel pressure in the high-pressure side passage 66. A check valve 65b. When the electromagnetic valve 65a is opened during operation of the engine 22, the high-pressure fuel pump 65 draws in fuel from the feed pump 62, and when the electromagnetic valve 65a is closed, power is supplied from the engine 22. The fuel supplied to the high-pressure side passage 66 is pressurized by intermittently sending the fuel compressed by an unillustrated plunger into the high-pressure side passage 66 via the check valve 65b. When the high-pressure fuel pump 65 is driven, the fuel pressure in the low-pressure passage 63 and the fuel pressure in the high-pressure passage 66 pulsate according to the rotation of the engine 22 (the rotation of the camshaft).

  The operation of the engine 22 and the fuel supply device 60 is controlled by an engine electronic control unit (hereinafter, referred to as “engine ECU”) 24. Although not shown, the engine ECU 24 is configured as a microprocessor centered on a CPU, and includes, in addition to the CPU, a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port. .

  Signals from various sensors necessary for controlling the operation of the engine 22 and controlling the fuel supply device 60 are input to the engine ECU 24 via input ports. The signals input to the engine ECU 24 include, for example, a crank position θcr from a crank position sensor 140 that detects the rotational position of the crankshaft 26 and a coolant temperature Tw from a coolant temperature sensor 142 that detects the temperature of the coolant of the engine 22. Can be mentioned. In addition, a cam position θca from a cam position sensor 144 that detects the rotational position of an intake camshaft that opens and closes the intake valve 128 and an exhaust camshaft that opens and closes the exhaust valve can also be used. Further, a throttle opening TH from a throttle valve position sensor 146 for detecting the position of the throttle valve 124, an intake air amount Qa from an air flow meter 148 attached to the intake pipe, and a temperature sensor 149 attached to the intake pipe. The intake air temperature Ta can also be mentioned. In addition, the air-fuel ratio AF1 from the first air-fuel ratio sensor 135a attached before the exhaust pipe purification device 134, and the air-fuel ratio AF from the second air-fuel ratio sensor 135b attached after the exhaust pipe purification device 134. AF2 and the catalyst temperature Tc from the temperature sensor 135c attached to the purification device 134 can also be mentioned. In the embodiment, the first air-fuel ratio sensor 135a and the second air-fuel ratio sensor 135b use an oxygen concentration sensor and detect a detection signal corresponding to the oxygen concentration in the exhaust gas corresponding to the air-fuel ratio AF1 and AF2. did. The rotation speed Nfp of the feed pump 62 from the rotation speed sensor 62a attached to the feed pump 62 of the fuel supply device 60, and the port injection from the fuel pressure sensor 68 attached near the port injection valve 125 in the low-pressure side passage 63. The fuel pressure Pfp of the fuel supplied to the valve 125 and the fuel pressure Pfd of the fuel supplied to the in-cylinder injection valve 126 from the fuel pressure sensor 69 attached near the in-cylinder injection valve 126 in the high pressure side passage 66 can also be mentioned.

  Various control signals for controlling operation of the engine 22 and controlling the fuel supply device 60 are output from the engine ECU 24 via output ports. The signals output from the engine ECU 24 include, for example, a drive signal to the port injection valve 125, a drive signal to the in-cylinder injection valve 126, a drive signal to the throttle motor 136 for adjusting the position of the throttle valve 124, and an integrated igniter. The control signal to the ignition coil 138 can be exemplified. Further, a drive control signal to the feed pump 62 and a drive control signal to the electromagnetic valve 65a of the high-pressure fuel pump 65 can also be mentioned.

  The engine ECU 24 is connected to the HVECU 70 via a communication port. The engine ECU 24 calculates the rotational speed Ne of the engine 22 based on the crank angle θcr from the crank position sensor 140. Note that the engine device corresponds to the engine 22, the fuel supply device 60, and the engine ECU 24.

  As shown in FIG. 1, the planetary gear 30 is configured as a single pinion type planetary gear mechanism. The rotor of the motor MG1 is connected to the sun gear of the planetary gear 30. A drive shaft 36 connected to drive wheels 39a and 39b via a differential gear 38 is connected to the ring gear of the planetary gear 30. The carrier of the planetary gear 30 is connected to the crankshaft 26 of the engine 22 via a damper 28.

  The motor MG1 is configured as, for example, a synchronous generator motor, and the rotor is connected to the sun gear of the planetary gear 30 as described above. The motor MG2 is configured as, for example, a synchronous generator motor, and has a rotor connected to the drive shaft 36. Inverters 41 and 42 are connected to motors MG1 and MG2 and to battery 50 via power line 54. The motors MG1 and MG2 are rotationally driven by a motor electronic control unit (hereinafter referred to as “motor ECU”) 40 in which a plurality of switching elements (not shown) of the inverters 41 and 42 are switching-controlled.

  Although not shown, the motor ECU 40 is configured as a microprocessor centered on a CPU, and includes, in addition to the CPU, a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port. . The motor ECU 40 receives signals from various sensors necessary for controlling the driving of the motors MG1 and MG2, for example, the rotational positions θm1 from the rotational position detection sensors 43 and 44 for detecting the rotational positions of the rotors of the motors MG1 and MG2. , Θm2, the temperature tm2 of the motor MG2 from the temperature sensor for detecting the temperature of the motor MG2, etc., are input via the input port. From the motor ECU 40, switching control signals to a plurality of switching elements (not shown) of the inverters 41 and 42 are output via output ports. The motor ECU 40 is connected to the HVECU 70 via a communication port. The motor ECU 40 calculates the rotational speeds Nm1 and Nm2 of the motors MG1 and MG2 based on the rotational positions θm1 and θm2 of the rotors of the motors MG1 and MG2 from the rotational position detection sensors 43 and 44.

  The battery 50 is configured as, for example, a lithium ion secondary battery or a nickel hydride secondary battery, and is connected to the inverters 41 and 42 via a power line 54. The battery 50 is managed by a battery electronic control unit (hereinafter, referred to as “battery ECU”) 52.

  Although not shown, the battery ECU 52 is configured as a microprocessor centered on a CPU, and includes, in addition to the CPU, a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port. . Signals from various sensors necessary for managing the battery 50 are input to the battery ECU 52 via input ports. The signals input to the battery ECU 52 include, for example, the battery voltage Vb from the voltage sensor 51a installed between the terminals of the battery 50, the battery current Ib from the current sensor 51b attached to the output terminal of the battery 50, the battery 50 And the battery temperature Tb from the temperature sensor 51c attached to the battery. Battery ECU 52 is connected to HVECU 70 via a communication port. The battery ECU 52 calculates the storage rate SOC based on the integrated value of the battery current Ib from the current sensor 51b. The power storage ratio SOC is a ratio of the capacity of the power that can be discharged from the battery 50 to the total capacity of the battery 50.

  Although not shown, the HVECU 70 is configured as a microprocessor centering on a CPU, and includes, in addition to the CPU, a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port. Signals from various sensors are input to the HVECU 70 via input ports. The signals input to the HVECU 70 include, for example, an ignition signal from an ignition switch 80 and a shift position SP from a shift position sensor 82 that detects an operation position of the shift lever 81. Further, the accelerator opening Acc from an accelerator pedal position sensor 84 that detects the amount of depression of an accelerator pedal 83, the brake pedal position BP from a brake pedal position sensor 86 that detects the amount of depression of a brake pedal 85, and the acceleration from a vehicle speed sensor 88. The vehicle speed V can also be mentioned. As described above, the HVECU 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via the communication port.

  In the hybrid vehicle 20 of the embodiment thus configured, the required driving force of the drive shaft 36 is set based on the accelerator opening Acc and the vehicle speed V, and the required power corresponding to the required driving force is output to the drive shaft 36. Next, the operation of the engine 22 and the motors MG1 and MG2 is controlled. The driving mode in which the engine 22 is driven using the motors MG1 and MG2 includes a motor driving mode in which the operation of the engine 22 is stopped and the vehicle is driven by the power from the motor MG2; And a hybrid traveling mode in which the vehicle travels with power from the motors MG1 and MG2.

  Next, an operation of the engine device mounted on the hybrid vehicle 20 of the embodiment configured as described above, particularly an operation for suppressing deterioration of the emission will be described. The fuel injection control of the engine 22 basically determines the basic fuel injection amount τ0 based on the intake air amount Qa from the air flow meter 148 and the intake air temperature Ta from the temperature sensor 149 so that the stoichiometric air-fuel ratio is obtained. The execution fuel injection amount τ is calculated by multiplying the basic fuel injection amount τ0 by various correction coefficients, and the opening time thereof is set so that the execution fuel injection amount τ is injected from the port injection valve 125 or the in-cylinder injection valve 126. The setting is performed. Then, feedback control is performed based on the air-fuel ratio AF1 detected by the first air-fuel ratio sensor 135a. In the engine device according to the embodiment, when unburned fuel (HC) or carbon monoxide (CO) is discharged from the purification device 134, if the engine 22 is operated with the air-fuel ratio corrected to the lean side, a relatively short time is obtained. The emission of unburned fuel (HC) and carbon monoxide (CO) can be stopped in time, but when nitrogen oxide (NOx) is emitted from the purification device 134, the air-fuel ratio is corrected to a rich side. Even when the engine is operated, nitrogen oxides (NOx) are emitted for a certain period of time. In the embodiment, fuel injection control for suppressing deterioration of emission is executed in consideration of such a phenomenon. FIG. 3 is a flowchart illustrating an example of a fuel injection amount correction processing routine executed by the engine ECU 24 while the engine 22 is operating. This routine is repeatedly executed at predetermined time intervals (for example, every several msec or every several tens msec).

  When the fuel injection amount correction processing routine is executed, the engine ECU 24 first determines whether the fuel for the engine 22 is being cut (step S100), and determines that the fuel is being cut. At this time, the value 0 is set to the lean correction execution flag F (step S150), and the routine ends. The lean correction execution flag F is set by this routine. When the lean correction for correcting the fuel injection amount from the stoichiometric air-fuel ratio to the lean side is performed, the value 1 is set, and the lean correction is performed. When it is not performed (during fuel cut and when rich correction is being executed), the value 0 is set. The reason why the value of the lean correction execution flag F is set to 0 during the fuel cut is that the air is supplied to the purifier 134 during the fuel cut, so that the purifying catalyst of the purifier 134 has a lean atmosphere, and the fuel cut is performed. This is because it is preferable to perform rich correction immediately after the cancellation. In the embodiment, the rich correction means that the fuel injection amount is corrected from the stoichiometric air-fuel ratio to the rich side.

  If it is determined in step S100 that the fuel cut is not being performed, it is determined whether the lean correction execution flag F is 0 (step S110). When it is determined that the lean correction execution flag F is 0, the air-fuel ratio AF2 from the second air-fuel ratio sensor 135b is input (step S120), and whether or not the input air-fuel ratio AF2 is equal to or more than the rich threshold AFref1. Is determined (step S130). The rich threshold value AFref1 is a value slightly smaller than the stoichiometric air-fuel ratio (14.6), and for example, 14.55 or the like can be used. When it is determined that the air-fuel ratio AF2 is equal to or greater than the rich threshold AFref1, rich correction is performed (step S140), a lean correction execution flag F is set to a value of 0 (step S150), and the routine ends. Therefore, the rich correction is continuously performed while the air-fuel ratio AF2 is equal to or larger than the rich threshold value AFref1.

  When it is determined in step S130 that the air-fuel ratio AF2 is less than the rich threshold AFref1, lean correction is performed instead of rich correction (step S170), and a value 1 is set to a lean correction execution flag F (step S180). Then, this routine ends. In this case, the next time this routine is executed, it is determined in step S110 that the lean correction execution flag F is not 0, and after the execution of the lean correction is started, the amount of oxygen stored in the catalyst of the purification device 134 ( It is determined whether or not the oxygen storage amount has reached a predetermined value (step S160). The determination as to whether or not the oxygen storage amount has reached the predetermined value can be made by, for example, multiplying the integrated value of the intake air amount at the time of lean correction by a correction coefficient. The integration of the intake air amount at the time of the lean correction may be based on a lean-time integrated air amount calculation processing routine illustrated in FIG. 6 described later. The lean threshold AFref2 is a value slightly larger than the stoichiometric air-fuel ratio (14.6), and for example, 14.65 or the like can be used. When it is determined that the oxygen storage amount of the catalyst has not reached the predetermined value since the start of the execution of the lean correction, the lean correction is continuously performed (step S170), and the lean correction execution flag F is set to a value of 1 (step S170). (Step S180), this routine ends. On the other hand, when it is determined that the oxygen storage amount of the catalyst has reached a predetermined value after the execution of the lean correction in step S160, the rich correction is performed instead of the lean correction (step S140), and the lean correction execution flag F is set. The value 0 is set (step S150), and this routine ends.

  FIG. 4 is an explanatory diagram showing an example of a time change of the air-fuel ratio AF2, the fuel correction, and the emission when the fuel injection amount correction processing routine of the embodiment is repeatedly executed. By performing the rich correction continuously, lean correction is performed instead of the rich correction at time T1 (time T3) when the air-fuel ratio AF2 crosses the rich side threshold AFref1 and becomes less than the rich side threshold AFref1. At this time, although unburned fuel (HC) and carbon monoxide (CO) may be emitted from the purification device 134, though slightly, the rich side threshold AFref1 is slightly richer than the stoichiometric air-fuel ratio (stoichiometric). For this reason, unburned fuel (HC) and carbon monoxide (CO) are not normally emitted from the purification device 134. FIG. 4 schematically shows a case where the liquid is slightly discharged to make it easy to understand. At time T2 (time T4) when the oxygen storage amount of the catalyst reaches a predetermined value after the execution of the lean correction is started, the rich correction is performed instead of the lean correction. Even if the lean correction is continuously performed over a period between time T1 and time T2, nitrogen oxides (NOx) are discharged from the purifier 134 only when the oxygen storage amount of the catalyst reaches a predetermined value. Never.

  When the above-described fuel injection amount correction processing routine of FIG. 3 is executed, the purification catalyst of the purification device 134 basically has a rich atmosphere. In order to sufficiently exert the function of the purifying device 134 and suppress the deterioration of the emission, it is necessary to periodically perform a fuel cut to make the purifying catalyst of the purifying device 134 lean. On the other hand, in the engine device of the embodiment, the catalyst deterioration suppression control for inhibiting the fuel cut of the engine 22 when the catalyst temperature Tc from the temperature sensor 135c is equal to or higher than the catalyst temperature threshold Tcref in order to suppress the deterioration of the catalyst of the purification device 134. Execute Therefore, it is necessary to adjust the fuel cut for suppressing the deterioration of the emission and the prohibition of the fuel cut for suppressing the catalyst deterioration. FIG. 5 is a flowchart showing an example of a catalyst adjustment processing routine executed by the engine ECU 24 to adjust the prohibition of the fuel cut by adjusting the purification catalyst and the fuel cut for suppressing catalyst deterioration. This routine is repeatedly executed every predetermined time (for example, every several msec or every several tens msec).

  When the catalyst adjustment processing routine is executed, the engine ECU 24 first determines whether or not the air-fuel ratio sensor 135b is in a normal functioning state (step S100). This determination is based on the fact that the signal line from the air-fuel ratio sensor 135b is not broken, the signal from the air-fuel ratio sensor 135b is not fixed to a specific value, and the temperature state is such that the air-fuel ratio sensor 135b can function. Judgment is based on the fact that there is.

  When it is determined in step S100 that the air-fuel ratio sensor 135b is in a normal functioning state, the lean-time integrated air amount Qlean calculation process (step S210), the rich-time integrated air amount Qrich calculation process (step S220), and the counter C Is executed (step S230), when it is determined that the air-fuel ratio sensor 135b is not in a normal functioning state, the lean-time integrated air amount Qlean, the rich-time integrated air amount Qrich, and the counter C are all reset to 0. (Step S240). The lean integrated air amount Qlean is an integrated value of the intake air amount when the air-fuel ratio AF2 from the air-fuel ratio sensor 135b is equal to or greater than the lean threshold AFref2, and is calculated by a lean integrated air amount calculation processing routine illustrated in FIG. Is done. The rich-time integrated air amount Qrich is an integrated value of the intake air amount when the air-fuel ratio AF2 from the air-fuel ratio sensor 135b is smaller than the rich-side threshold value AFref1, and is calculated by a rich-time integrated air amount calculation processing routine illustrated in FIG. Is done. The counter C is the number of times the air-fuel ratio AF2 has become less than the rich side threshold AFref1 during the operation of the engine 22, and is set by a counter processing routine illustrated in FIG. For the sake of simplicity, the description of the catalyst adjustment process will be interrupted, and the calculation process of the lean accumulated air amount Qlean, the rich accumulated air amount Qrich, and the counter process of the counter C will be described with reference to FIGS. explain.

  As shown in the lean-time integrated air amount calculation processing routine illustrated in FIG. 6, the air-fuel ratio AF2 from the air-fuel ratio sensor 135b is input first (step S300), and the engine 22 calculates the lean-time integrated air amount Qlean. It is determined whether or not the fuel is being cut as the operation state (step S310). When it is determined that the fuel is being cut, a value k1 during the fuel cut is set as the correction coefficient k (step S320), and when it is determined that the fuel is not being cut, a value k2 smaller than the value k1 is set as the correction coefficient k. (Step S330). Here, the correction coefficient k reflects the amount of air in the exhaust gas when the fuel is cut and when the fuel is not cut. For example, k1 = 1.0 and k2 = 0.2 can be used. . Subsequently, it is determined whether or not the air-fuel ratio AF2 is smaller than the rich threshold AFref1 (step S340). When it is determined that the air-fuel ratio AF2 is less than the rich side threshold value AFref1, the lean accumulated air amount Qlean is cleared to a value of 0 (step S360), and this routine ends. When it is determined that the air-fuel ratio AF2 is equal to or greater than the rich threshold AFref1, it is determined whether the air-fuel ratio AF is equal to or greater than the lean threshold AFref2 (step S350). When it is determined that the air-fuel ratio AF is equal to or greater than the lean threshold AFref2, a value obtained by multiplying the correction coefficient k by the intake air amount Qa to the lean integrated air amount Qlean at that time is added to obtain a new lean integrated air amount Qlean. (Step S370), this routine ends. On the other hand, when it is determined that the air-fuel ratio AF is less than the lean-side threshold value AFref2, the lean-time integrated air amount Qlean at that time is held (step S380), and this routine ends.

  As shown in the rich-time integrated air amount calculation processing routine illustrated in FIG. 7, the air-fuel ratio AF2 from the air-fuel ratio sensor 135b is first input (step S400) to calculate the rich-time integrated air amount Qrich. It is determined whether or not AF2 is equal to or greater than the lean threshold AFref2 (step S410), and whether or not the lean accumulated air amount Qlean is equal to or greater than the threshold Qref2 (step S420). The threshold value Qref2 is an integrated value of the intake air amount such that the purifying catalyst completely enters the lean atmosphere when the air-fuel ratio AF2 detected at the subsequent stage of the purifying device 134 is equal to or more than the lean-side threshold value AFref2. Can be. When it is determined that the air-fuel ratio AF2 is equal to or greater than the lean threshold AFref2 and the lean accumulated air amount Qlean is greater than or equal to the threshold Qref2, the rich accumulated air amount Qrich is cleared to a value of 0 (step S450). End the routine. When the air-fuel ratio AF2 is less than the lean threshold AFref2 or when the lean accumulated air amount Qlean is less than the threshold Qref2, it is determined whether the air-fuel ratio AF2 is less than the rich threshold AFref1 (step S430). When it is determined that the air-fuel ratio AF2 is less than the rich-side threshold value AFref1, the intake air amount Qa is added to the rich-time integrated air amount Qrich at that time to obtain a new rich-time integrated air amount Qrich (step S460). finish. On the other hand, when it is determined that the air-fuel ratio AF is equal to or larger than the rich side threshold value AFref1, the rich accumulated air amount Qrich at that time is held (step S470), and this routine ends.

  In the counter processing of the counter C, as shown in the counter processing routine illustrated in FIG. 8, first, the air-fuel ratio AF2 from the air-fuel ratio sensor 135b is input (step S500), and the air-fuel ratio AF2 is equal to or greater than the lean threshold AFref2. It is determined whether or not (step S510), and whether or not the lean accumulated air amount Qlean is equal to or larger than the threshold value Qref2 (step S520). When it is determined that the air-fuel ratio AF2 is equal to or greater than the lean threshold AFref2 and the lean accumulated air amount Qlean is equal to or greater than the threshold Qref2, the counter C is cleared to 0 (step S530), and the routine ends. . When the air-fuel ratio AF2 is less than the lean threshold AFref2 or when the lean accumulated air amount Qlean is less than the threshold Qref2, it is determined whether the air-fuel ratio AF2 is less than the rich threshold AFref1 (step S540). It is determined whether the air-fuel ratio AF2 at the time of execution is equal to or greater than the rich threshold AFref1 (step S550) and whether the engine 22 is operating (step S560). These determinations are for determining when the air-fuel ratio AF2 becomes less than the rich side threshold AFref1 during the operation of the engine 22, and the switching from the rich correction to the lean correction is performed by the fuel injection amount correction processing routine of FIG. The time will be determined. When the air-fuel ratio AF2 is less than the rich-side threshold AFref1 and the air-fuel ratio AF2 obtained when this routine was previously executed is equal to or more than the rich-side threshold AFref1 and the engine 22 is operating, the counter C is incremented by one. Then (step S570), this routine ends. On the other hand, when the air-fuel ratio AF2 is equal to or greater than the rich threshold AFref1, when the air-fuel ratio AF2 when this routine was executed last time is less than the rich threshold AFref1, or when the engine 22 is intermittently stopped, the counter at that time is used. C is held (step S580), and this routine ends.

  Return to the description of the catalyst adjustment processing. When the lean accumulated air amount Qlean, the rich accumulated air amount Qrich, and the counter C are calculated in this manner, the catalyst temperature Tc from the temperature sensor 135c is input (step S250), and the counter C is equal to or greater than the threshold value Cref. It is determined whether the amount Qrich is equal to or more than the threshold value Qref1 and whether the catalyst temperature Tc is less than the threshold value Tref (step S260). Here, the threshold value Tref is determined in advance as a temperature of the catalyst at which the fuel cut needs to be prohibited due to the need to suppress the deterioration of the catalyst, and can be determined according to the catalyst. For example, 850 ° C. or 900 ° C. Etc. can be used. When the counter C is equal to or more than the threshold value Cref, the rich accumulated air amount Qrich is equal to or more than the threshold value Qref1, and the catalyst temperature Tc is less than the threshold value Tref, it is determined that the purifying catalyst needs to be once set to the lean atmosphere, A cut is requested (step S270), and a value Tset is set to the catalyst temperature threshold Tcref used for the catalyst deterioration suppression control (step S275), and this routine ends. On the other hand, when the counter C is less than the threshold value Cref, the rich accumulated air amount Qrich is less than the threshold value Qref1, or the catalyst temperature Tc is equal to or more than the threshold value Tref, the request for fuel cut is cleared (step S280), and the catalyst is cleared. The normal value Tbase is set as the catalyst temperature threshold Tcref used for the deterioration suppression control (step S285), and this routine ends. The value Tbase set as the normal catalyst temperature threshold Tcref is the upper limit temperature of the temperature range where the catalyst does not deteriorate or a temperature slightly lower than the upper limit temperature, and can be determined according to the catalyst. C. can be used. The value Tset set to the catalyst temperature threshold value Tcref when requesting the fuel cut is a temperature of the catalyst which must be prohibited from being cut off because of the need to suppress the deterioration of the catalyst, similarly to the threshold value Tref. Or a slightly different temperature can be used, and the temperature is higher than the value Tbase. When a fuel cut is requested, the fuel cut is performed when the fuel cut execution condition is satisfied, the air is supplied to the purification device 134, and the purification catalyst enters a lean atmosphere.

  In the engine device of the embodiment described above, the fuel injection amount is rich-corrected until the air-fuel ratio AF2 from the air-fuel ratio sensor 135b attached downstream of the purification device 134 becomes less than the rich threshold AFref1, and the air-fuel ratio AF2 becomes rich. When the air-fuel ratio AF2 becomes less than the lean threshold AFref2, lean correction is performed to the extent that the air-fuel ratio AF2 does not become more than the lean threshold AFref2 (the oxygen storage amount becomes more than a predetermined value). The fuel injection amount is richly corrected until the time is reached. Thereby, emission of nitrogen oxides (NOx) can be suppressed, and deterioration of emission can be suppressed. The counter C counts the number of times that the air-fuel ratio AF2 has become less than the rich threshold AFref1, and calculates the rich integrated air amount as the integrated value of the intake air amount Qa when the air-fuel ratio AF2 is less than the rich threshold AFref1. Qrich is calculated, and when the counter C is equal to or greater than the threshold value Cref, the rich-time integrated air amount Qrich is equal to or greater than the threshold value Qref1, and the catalyst temperature Tc is less than the threshold value Tref, a fuel cut is requested. When the fuel cut is performed in response to the fuel cut request, the purification catalyst of the purification device 134 temporarily has a lean atmosphere. Thereby, the function of the purification catalyst of the purification device 134 can be sufficiently exhibited, and deterioration of emission can be suppressed. Since the counter C holds the value when the engine 22 is intermittently stopped, the purification catalyst of the purification device 134 is temporarily set to a lean atmosphere as compared with the counter C that resets the value of the counter C to 0 when the operation of the engine 22 is stopped. An opportunity can be obtained, and it is possible to avoid that the air-fuel ratio of the exhaust gas from the purification device 134 is always on the rich side and the emission is deteriorated. Further, when the counter C becomes equal to or more than the threshold value Cref and a fuel cut is requested in order to temporarily make the purifying device 134 a lean atmosphere, the catalyst temperature threshold Tcref is set to a value Tset higher than the normal value Tbase. Execution of suppression control (prohibition of fuel cut) is suppressed. For this reason, the execution condition of the fuel cut is easily satisfied, and the opportunity of executing the fuel cut increases. As a result, both suppression of deterioration of emission and suppression of deterioration of the catalyst of the purification device can be achieved. Since the requirement for the fuel cut requirement is that the rich accumulated air amount Qrich is equal to or larger than the threshold value Qref1, it is possible to suppress excessive fuel cut. As a result, emission deterioration can be suppressed.

  In the engine device of the embodiment, the fuel cut is requested when the counter C is equal to or more than the threshold value Cref, the rich accumulated air amount Qrich is equal to or more than the threshold value Qref1, and the catalyst temperature Tc is less than the threshold value Tref. . However, when the counter C is equal to or larger than the threshold value Cref, the fuel cut may be requested regardless of the rich accumulated air amount Qrich or the catalyst temperature Tc.

  In the engine device of the embodiment, the present invention is applied to the engine 22 including the port injection valve 125 and the in-cylinder injection valve 126. However, the invention is applied to an engine having only the port injection valve or an engine having only the in-cylinder injection valve. May be applied.

  In the engine device of the embodiment, the hybrid vehicle having the engine 22, the two motors MG1, MG2, and the planetary gear 30 is mounted. However, the hybrid device having the engine is mounted on any hybrid vehicle. It may be mounted on a normal vehicle without a motor for running.

  As described above, the embodiments for carrying out the present invention have been described using the embodiments. However, the present invention is not limited to these embodiments at all, and various forms may be used without departing from the gist of the present invention. Of course, it can be implemented.

  INDUSTRIAL APPLICABILITY The present invention is applicable to an engine device manufacturing industry and the like.

  20 hybrid vehicle, 22 engine, 24 engine electronic control unit (engine ECU), 26 crankshaft, 28 damper, 30 planetary gear, 36 drive shaft, 38 differential gear, 39a, 39b drive wheel, 40 motor electronic control unit (motor ECU, 41, 42 inverter, 43, 44 rotational position detection sensor, 50 battery, 51a voltage sensor, 51b current sensor, 51c temperature sensor, 52 battery electronic control unit (battery ECU), 54 power line, 60 fuel supply device , 61 fuel tank, 62 feed pump, 62a speed sensor, 63 low pressure side passage, 64 check valve, 65 high pressure fuel pump, 65a solenoid valve, 65b check valve, 66 high pressure side passage, 68, 69 fuel pressure sensor , 70 hybrid electronic control unit (HVECU), 80 ignition switch, 81 shift lever, 82 shift position sensor, 83 accelerator pedal, 84 accelerator pedal position sensor, 85 brake pedal, 86 brake pedal position sensor, 88 vehicle speed sensor, 122 Air cleaner, 124 throttle valve, 125 port injection valve, 126 in-cylinder injection valve, 128 intake valve, 130 spark plug, 132 piston, 134 purifier, 135a air-fuel ratio sensor, 135b air-fuel ratio sensor, 135c temperature sensor, 136 throttle motor, 138 Ignition coil, 140 Crank position sensor, 142 Water temperature sensor, 144 Cam position sensor, 146 Throttle valve position Sensor, 148 an air flow meter, 149 temperature sensor, MG1, MG2 motor.

Claims (1)

An engine having a purification device for purifying exhaust gas;
An air-fuel ratio sensor that detects an air-fuel ratio at a later stage of the purification device,
A rich correction process for richly correcting the air-fuel ratio until the air-fuel ratio detected by the air-fuel ratio sensor becomes equal to or less than a rich-side threshold; and when the air-fuel ratio detected by the air-fuel ratio sensor becomes equal to or less than the rich-side threshold. And a fuel cut-off process for repeating a lean correction process of lean-correcting the air-fuel ratio over a predetermined period, and a fuel cut-off to suppress catalyst deterioration when the catalyst temperature of the purifier is equal to or higher than a catalyst temperature threshold. A control device for executing catalyst deterioration suppression control for inhibiting
An in-vehicle engine device comprising:
The control device includes:
The air-fuel ratio counter is counted up when the air-fuel ratio detected by the air-fuel ratio sensor is equal to or less than the rich side threshold, and the air-fuel ratio counter is held while the engine is stopped due to intermittent operation. When the integrated value of the intake air amount in a state where the air-fuel ratio detected by the air-fuel ratio sensor is equal to or greater than the lean side threshold value is equal to or greater than a predetermined air amount, a counter process for resetting the air-fuel ratio counter to a value of 0 is performed,
Requesting a fuel cut when the air-fuel ratio counter is equal to or greater than a predetermined count value, and setting a second temperature higher than a first temperature when the air-fuel ratio counter is less than the predetermined count value as the catalyst temperature threshold value;
Engine equipment.

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