JP6534864B2 - Engine control device - Google Patents

Description

  The present invention relates to a control device for an engine, and more particularly to a control device for an engine that prohibits the execution of a fuel cut when the exhaust purification catalyst is at a high temperature.

  Conventionally, in fuel injection control of an engine, in order to improve a fuel consumption rate (fuel consumption), for example, when the depression of an accelerator pedal is released and the engine speed is equal to or more than a predetermined speed (for example, during deceleration) A fuel cut is performed to temporarily stop fuel injection to the engine.

  By the way, if fuel cut is performed in a state where the exhaust gas purification catalyst (hereinafter, also simply referred to as "catalyst") for purifying exhaust gas discharged from the engine is at high temperature, lean exhaust gas (oxygen) flows into the catalyst And the catalyst may be deteriorated. Therefore, it has been proposed to prohibit the fuel cut depending on the temperature of the catalyst. However, if fuel cut is prohibited at the time of deceleration (that is, if fuel injection is continued), deceleration by the engine brake can not be provided, so the deceleration of the vehicle decreases and a feeling of free running is generated. May cause discomfort.

  In order to solve such problems, Patent Document 1 discloses a technique for preventing the deterioration of the feeling of deceleration of the vehicle when prohibiting the fuel cut at the time of deceleration in order to prevent the deterioration of the catalyst under high temperature lean atmosphere. (A fuel cut control device for an internal combustion engine) is disclosed. More specifically, in the technique of Patent Document 1, when prohibiting fuel cut at the time of deceleration from the viewpoint of preventing catalyst deterioration, downshifting of the automatic transmission is performed. That is, in this technology, the engine load is increased and the deceleration of the vehicle is increased by switching the shift position of the automatic transmission to a smaller shift position (shifting down).

JP 10-280990 A

  By the way, when the shift stage of the automatic transmission is switched to a smaller shift stage (downshifted) at the time of deceleration, the engine rotational speed is increased accordingly, thereby increasing the engine friction. The intake air amount increases, and the fuel injection amount also increases accordingly. As a result, the engine output increases, and there is a possibility that the deterioration preventing effect of the feeling of deceleration may be reduced. In addition, the fuel consumption rate (fuel consumption) may be deteriorated.

  The present invention has been made to solve the above problems, and is an engine control device that prohibits the execution of fuel cut when the exhaust purification catalyst is at a high temperature, and the execution of the fuel cut is prohibited. It is an object of the present invention to provide an engine control device capable of effectively preventing the deterioration of the feeling of deceleration (feeling of free running) without deteriorating the fuel efficiency.

  The engine control device according to the present invention cleans the exhaust gas discharged from the engine and the fuel injection control means that executes the fuel cut to stop the fuel injection to the engine when the predetermined fuel injection stop condition is satisfied. A catalyst temperature acquisition unit that acquires the temperature of the exhaust purification catalyst, and a fuel cut that prohibits execution of fuel cut by the fuel injection control unit when the temperature of the exhaust purification catalyst acquired by the catalyst temperature acquisition unit is higher than a predetermined temperature Fuel cut is performed when execution of fuel cut is prohibited by the prohibiting means, the exhaust gas recirculation device that recirculates part of the exhaust gas discharged from the engine to the intake system of the engine, and the fuel cut prohibiting means Requests to change the gear ratio of the automatic transmission that converts and outputs the driving force of the engine to the low side than when it is being When the fuel cut is prohibited by the step and the fuel cut prohibiting means, the amount of exhaust gas to be recirculated to the engine intake system is increased more than when the fuel cut is performed. And a reflux amount control means for driving the circulation device.

  According to the engine control device according to the present invention, when the temperature of the exhaust purification catalyst becomes higher than the predetermined temperature and fuel cut is prohibited, the transmission gear ratio of the automatic transmission is changed to the low side. Therefore, the engine rotational speed is increased, and the engine friction is increased. Thus, the deceleration of the vehicle can be increased. On the other hand, when fuel cut is prohibited, the amount of exhaust gas recirculated to the engine intake system is increased. Therefore, even if the engine speed is increased, the increase in fresh air drawn into the engine is suppressed, and the increase in fuel injection amount is suppressed. Thus, an increase in engine output can be suppressed. As a result, when the fuel cut is prohibited from the viewpoint of preventing the deterioration of the exhaust purification catalyst, it is possible to effectively prevent the deterioration of the feeling of deceleration (the feeling of idling) without deteriorating the fuel consumption. Become.

  In the engine control device according to the present invention, when the execution of the fuel cut is prohibited, the amount of intake air at the minimum engine rotational speed that can be operated in the state where the execution of the fuel cut is prohibited. It is preferable to increase the amount of exhaust gas recirculation based on the deviation of the amount of intake air at the target engine rotational speed that is set higher than the minimum engine rotational speed.

  In this case, when execution of fuel cut is prohibited, the amount of exhaust gas recirculated to the intake system of the engine based on the deviation between the amount of intake air at the minimum engine speed and the amount of intake air at the target engine speed. The amount is increased. Therefore, even if the engine speed has increased to the target speed, the amount of fresh air taken into the engine is maintained at the same amount as the amount of intake air at the minimum engine speed, and an increase in the fuel injection amount is suppressed. Ru. Therefore, an increase in engine output can be appropriately suppressed.

  In the engine control device according to the present invention, when the fuel cut is prohibited, the shift request means is higher in rotational speed than the minimum engine speed that can be operated in the state in which the fuel cut is prohibited. It is preferable to request that the transmission gear ratio of the automatic transmission be changed to the low side based on the target engine rotational speed set to.

  In this case, when the execution of the fuel cut is prohibited, the transmission gear ratio of the automatic transmission is changed to the low side based on the target engine rotation speed set higher than the minimum engine rotation speed. Therefore, the engine speed can be increased to the target engine speed.

  The engine control device according to the present invention includes throttle valve control means for adjusting the amount of air taken into the engine according to the amount of operation of the accelerator pedal, and the throttle valve control means prohibits execution of fuel cut. The throttle valve opening is adjusted so that the amount of fresh air that is the same as the amount of intake air at the minimum engine speed is inhaled, and the fuel injection control means prohibits the fuel cut from being performed. Preferably, the injector is controlled to inject the same amount of fuel as the fuel injection amount at the minimum engine speed.

  In this way, execution of fuel cut is prohibited, and when the engine speed is increased, the amount of fresh air taken into the engine is adjusted to be the same as the amount of intake air at the lowest engine speed. The fuel injection amount is controlled to be the same as the fuel injection amount at the minimum engine speed. Therefore, when the engine speed increases, it is possible to prevent an increase in engine output.

  In the engine control device according to the present invention, it is preferable that the catalyst temperature acquisition means estimate the temperature of the exhaust purification catalyst based on the engine speed, the engine load, the air-fuel ratio, and the ignition timing.

  In this way, the temperature of the exhaust gas purification catalyst can be estimated accurately without using a dedicated temperature sensor.

  According to the present invention, when fuel cut is prohibited from the viewpoint of preventing the deterioration of the exhaust purification catalyst, it is possible to effectively prevent the deterioration of the feeling of deceleration (the feeling of idling) without deteriorating the fuel consumption. It becomes.

It is a figure showing the control device of the engine concerning an embodiment, and the composition of the engine to which the control device is applied. It is a flow chart which shows a processing procedure of fuel cut prohibition processing (air run feeling reduction processing) by a control device of an engine concerning an embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals are used for the same or corresponding parts. Further, in the respective drawings, the same elements are denoted by the same reference numerals, and duplicate explanations will be omitted.

  First, the configuration of an engine control device 1 according to the embodiment will be described using FIG. 1. FIG. 1 is a diagram showing a control device 1 of an engine, and a configuration of an engine 10 and a continuously variable transmission 81 (power unit) to which the control device 1 is applied.

  The engine 10 is, for example, a horizontally opposed four-cylinder gasoline engine. The engine 10 is an in-cylinder injection type engine that directly injects fuel into a cylinder (in a cylinder). In the engine 10, the air taken in from the air cleaner 16 is throttled by an electronically controlled throttle valve (hereinafter simply referred to as “throttle valve”) 13 provided in the intake pipe 15, passes through the intake manifold 11, and passes through to the engine 10. It is sucked into each of the formed cylinders. Here, the amount of air drawn from the air cleaner 16 is detected by an air flow meter 14 disposed between the air cleaner 16 and the throttle valve 13. Further, a vacuum sensor 30 for detecting the pressure in the intake manifold 11 (intake manifold pressure) is disposed inside the collector portion (surge tank) constituting the intake manifold 11. Further, a throttle opening degree sensor 31 for detecting the opening degree of the throttle valve 13 is disposed in the throttle valve 13.

  In the cylinder head, an intake port 22 and an exhaust port 23 are formed for each cylinder (only one bank is shown in FIG. 1). Each of the intake port 22 and the exhaust port 23 is provided with an intake valve 24 and an exhaust valve 25 for opening and closing the intake port 22 and the exhaust port 23. The intake cam pulley and the intake camshaft are relatively rotated between the intake camshaft and the intake cam pulley that drive the intake valve 24 to continuously change the rotational phase (displacement angle) of the intake camshaft with respect to the crankshaft 10a. A variable valve timing mechanism 26 is provided to advance and retard the valve timing (opening and closing timing) of the intake valve 24. The variable valve timing mechanism 26 variably sets the open / close timing of the intake valve 24 according to the engine operating state.

  Similarly, between the exhaust camshaft and the exhaust cam pulley, the exhaust cam pulley and the exhaust camshaft are relatively rotated to continuously change the rotational phase (displacement angle) of the exhaust camshaft relative to the crankshaft 10a. A variable valve timing mechanism 27 for advancing and retarding the valve timing (opening and closing timing) of the exhaust valve 25 is disposed. The variable valve timing mechanism 27 variably sets the open / close timing of the exhaust valve 25 according to the engine operating state.

  Each cylinder of the engine 10 is provided with an injector 12 for injecting fuel into the cylinder. The injector 12 directly injects the fuel pressurized by a high pressure fuel pump (not shown) into the combustion chamber of each cylinder.

  Further, an ignition plug 17 for igniting the air-fuel mixture and an igniter built-in coil 21 for applying a high voltage to the ignition plug 17 are attached to the cylinder head of each cylinder. In each cylinder of the engine 10, a mixture of intake air and fuel injected by the injector 12 is ignited by the spark plug 17 and burns. Exhaust gas after combustion is exhausted through the exhaust pipe 18.

Attached to the exhaust pipe 18 is an air-fuel ratio sensor 19A that outputs a signal corresponding to the oxygen concentration in the exhaust gas. As the air-fuel ratio sensor 19A, a linear air-fuel ratio sensor (LAF sensor) capable of linearly detecting the exhaust air-fuel ratio is used. As the air-fuel ratio sensor 19A, an O ₂ sensor that detects the exhaust air-fuel ratio on / off may be used.

Further, an exhaust purification catalyst (CAT) 20 is disposed downstream of the air-fuel ratio sensor 19A. The exhaust purification catalyst 20 is a three-way catalyst, which simultaneously oxidizes hydrocarbon (HC) and carbon monoxide (CO) in the exhaust gas and reduces nitrogen oxides (NOx), thereby reducing harmful gas components in the exhaust gas. Is purified to harmless carbon dioxide (CO ₂ ), water vapor (H ₂ O) and nitrogen (N ₂ ). Downstream of the exhaust purification catalyst 20, the exhaust gas air-fuel ratio on - are provided off-detectable to the rear (after CAT) O ₂ sensor 19B.

  An exhaust gas recirculation device (hereinafter referred to as “EGR (Exhaust Gas Recirculation)”) which recirculates (recirculates) a part of the exhaust gas discharged from the engine 10 to the intake manifold 11 (intake system) of the engine 10 into the exhaust pipe 18 The device 40) is provided. The EGR device 40 has an EGR pipe 41 communicating the exhaust pipe 18 of the engine 10 with the intake manifold 11, and an EGR valve 42 interposed on the EGR pipe 41 to adjust the exhaust gas recirculation amount (EGR amount). ing.

  The opening degree of the EGR valve 42 is controlled (duty control) by an electronic control unit 50 described later. That is, the electronic control unit 50 controls the amount of recirculation (recirculation amount) of the exhaust gas by adjusting the opening / closing amount of the EGR valve 42 in accordance with the operating state of the engine 10. In addition to the negative pressure type, the EGR valve 42 may be of a type driven by a stepping motor or the like.

In addition to the air flow meter 14, the LAF sensor 19A, the O ₂ sensor 19B, the vacuum sensor 30, and the throttle opening degree sensor 31 described above, a cam angle sensor 32 for performing cylinder discrimination of the engine 10 near the camshaft of the engine 10. It is attached. Further, in the vicinity of the crankshaft 10 a of the engine 10, a crank angle sensor 33 for detecting the rotational position of the crankshaft 10 a is attached. Here, at the end of the crankshaft 10a, for example, a timing rotor 33a having 34 teeth projections with two missing teeth formed at intervals of 10 ° is attached, and the crank angle sensor 33 is of the timing rotor 33a. By detecting the presence or absence of the protrusion, the rotational position of the crankshaft 10a is detected. As the cam angle sensor 32 and the crank angle sensor 33, for example, an electromagnetic pickup type is used.

  These sensors are connected to an electronic control unit (hereinafter referred to as "ECU") 50. Further, the ECU 50 includes a water temperature sensor 34 for detecting the temperature of the cooling water of the engine 10, an oil temperature sensor 35 for detecting the temperature of the lubricating oil, and an accelerator pedal opening degree for detecting the depression amount of the accelerator pedal, that is, the opening degree of the accelerator pedal. Various sensors such as a sensor 36 and a vehicle speed sensor 37 for detecting the speed of the vehicle are also connected.

  The ECU 50 is a microprocessor for performing calculations, a ROM for storing programs for causing the microprocessor to execute each process, a RAM for storing various data such as calculation results, a backup RAM for storing the stored contents by a battery, And an input / output I / F. The ECU 50 further includes an injector driver for driving the injector 12, an output circuit for outputting an ignition signal, a driver for driving the EGR valve 42, and a motor driver for driving the electric motor 13a for opening and closing the electronically controlled throttle valve 13. ing.

  In the ECU 50, the cylinder is determined from the output of the cam angle sensor 32, and the rotational angular velocity and the engine rotational speed are obtained from the output of the crank angle sensor 33. Further, in the ECU 50, based on the detection signals inputted from the various sensors described above, various items such as intake air amount, intake pipe negative pressure, accelerator pedal opening degree, air-fuel ratio of air-fuel mixture, water temperature and oil temperature of the engine 10 Information is acquired. Then, the ECU 50 comprehensively controls the engine 10 by controlling various devices such as the fuel injection amount and the ignition timing, the EGR valve 42, and the throttle valve 13 based on the acquired various information.

  In particular, when prohibiting the fuel cut from the viewpoint of preventing the deterioration of the exhaust purification catalyst 20, the ECU 50 has a function to effectively prevent the deterioration of the feeling of deceleration (the feeling of free running) without deteriorating the fuel consumption. doing. Therefore, the ECU 50 functionally includes a fuel injection control unit 51, a catalyst temperature acquisition unit 52, a fuel cut prohibition unit 53, a shift request unit 54, a reflux amount control unit 55, and a throttle valve control unit 56. In the ECU 50, the program stored in the ROM is executed by the microprocessor, whereby the fuel injection control unit 51, the catalyst temperature acquisition unit 52, the fuel cut prohibition unit 53, the shift request unit 54, the reflux amount control unit 55, and Each function of the throttle valve control unit 56 is realized.

  The fuel injection control unit 51 stops the driving of the injector 12 and stops the fuel supply to the engine 10 (hereinafter referred to as "fuel cut") when a predetermined fuel injection stop condition is satisfied, such as during deceleration. That is, the fuel injection control unit 51 functions as a fuel injection control unit described in the claims. More specifically, fuel injection control unit 51, for example, when the following fuel cut start condition (hereinafter, also simply referred to as "fuel cut condition") is satisfied, that is, the accelerator pedal is fully closed, the engine A fuel cut is performed when the rotation speed Ne 1000 1000 (rpm) and the vehicle speed v 10 10 (km / h).

  Here, although the predetermined fuel cut condition described above is satisfied, the fuel injection control unit 51 prohibits the execution of the fuel cut when the execution of the fuel cut is prohibited by the fuel cut prohibition unit 53 described later. The injector 12 is controlled to inject the same amount of fuel as the fuel injection amount at the minimum engine speed Nmin that can be operated in the above state.

  When the fuel cut condition is not satisfied during the fuel cut, the fuel injection control unit 51 interrupts the fuel cut and restarts the fuel injection by the injector 12 (returns from the fuel cut).

  The catalyst temperature acquisition unit 52 acquires the temperature of the exhaust purification catalyst 20 that purifies the exhaust gas discharged from the engine 10. That is, the catalyst temperature acquisition unit 52 functions as a catalyst temperature acquisition unit described in the claims. More specifically, the catalyst temperature acquisition unit 52 estimates the temperature of the exhaust purification catalyst 20 based on, for example, the engine speed, the engine load, the air-fuel ratio of the mixture, and the ignition timing.

  More specifically, a map (catalyst temperature estimation map) defining in advance the relationship between the engine speed, the engine load, the air-fuel ratio of the mixture, and the ignition timing and the temperature of the exhaust purification catalyst 20 is previously stored in the ROM of the ECU 50 The temperature of the exhaust purification catalyst 20 can be estimated by searching the catalyst temperature estimation map using the stored engine rotational speed, engine load, air-fuel ratio, and ignition timing. Further, instead of the map, the temperature of the exhaust purification catalyst 20 may be estimated by calculation using an arithmetic expression having the engine speed, the engine load, the air fuel ratio, and the ignition timing as parameters. The temperature of the exhaust purification catalyst 20 estimated by the catalyst temperature acquisition unit 52 is output to the fuel cut prohibition unit 53.

  If the temperature of the exhaust purification catalyst 20 estimated (acquired) by the catalyst temperature acquisition unit 52 is higher than a predetermined temperature Tfc (for example, 600 to 700 ° C.), the fuel cut prohibition unit 53 causes the exhaust purification catalyst 20 to deteriorate. In order to prevent this, execution of fuel cut by the fuel injection control unit 51 is prohibited. That is, the fuel cut prohibition unit 53 functions as a fuel cut prohibition unit described in the claims. The information indicating that the fuel cut is prohibited by the fuel cut prohibition unit 53 is output to the fuel injection control unit 51, the shift request unit 54, the return amount control unit 55, and the throttle valve control unit 56. .

  The shift request unit 54 converts and outputs 10 driving forces of the engine, for example, when the fuel cut inhibiting unit 53 prohibits the fuel cut from being executed, than when the fuel cut is executed. The transmission ratio of the continuously variable transmission (corresponding to the automatic transmission described in the claims) 81 is required to be changed to the low side. That is, the shift request unit 54 functions as shift request means described in the claims.

  More specifically, when the fuel cut is prohibited, the shift request unit 54 sets the rotation speed higher than the minimum engine speed Nmin that can be operated in a state where the fuel cut is prohibited. Request to change the gear ratio of continuously variable transmission 81 to the low side based on the target engine rotation speed (for example, about 1000 rpm) (that is, the actual engine rotation speed matches the target engine rotation speed) Do. At this time, the shift request unit 54 sends request information to the TCU 80 (transmission control unit) that controls the transmission ratio of the continuously variable transmission 81 via the CAN 100. Note that the TCU 80 receives the shift request from the shift request unit 54 and changes the gear ratio of the continuously variable transmission 81 to the low side.

  When the fuel cut inhibiting unit 53 prohibits the fuel cut from being performed, the reflux amount control unit 55 sets the amount of exhaust gas to be recirculated to the intake manifold 11 of the engine 10 more than when the fuel cut is being executed. The EGR valve 42 is driven to increase. That is, the reflux amount control unit 55 functions as a reflux amount control unit described in the claims.

  More specifically, when the execution of the fuel cut is prohibited, the return flow control unit 55 sets the intake air amount at the minimum engine speed Nmin that can be operated in the state where the execution of the fuel cut is prohibited; The amount of fresh air taken into the engine 10 does not change based on the deviation from the amount of intake air at a target engine rotational speed (for example, about 1000 rpm) set higher than the minimum engine rotational speed Nmin As such, the EGR valve 42 is driven to increase the amount of exhaust gas recirculation.

  The throttle valve control unit 56 adjusts the amount of intake air of the engine 10 by driving the electric motor 13 a to adjust the opening degree of the throttle valve 13. During normal operation, for example, the throttle valve control unit 56 obtains a target throttle opening degree from the accelerator opening degree (the depression amount of the accelerator pedal) detected by the accelerator opening degree sensor 36, and the target throttle opening degree and the actual opening degree. Drive the electric motor 13a so as to match. More specifically, the ROM of the ECU 50 stores a throttle opening map that defines the relationship between the accelerator opening and the throttle opening, and this throttle opening map is searched based on the accelerator opening. As a result, the target value of the throttle opening is set.

  On the other hand, when the fuel cut prohibiting portion 53 prohibits the fuel cut from being performed by the fuel cut prohibiting portion 53, the throttle valve control portion 56 causes the throttle valve to draw in the same amount of fresh air as the intake air amount at the minimum engine speed Nmin. Adjust the opening of 13. That is, the throttle valve control unit 56 functions as a throttle valve control unit described in the claims.

  Next, the operation of the engine control device 1 will be described with reference to FIG. FIG. 2 is a flowchart showing a processing procedure of a fuel cut prohibition process (a feeling of runaway reduction processing) by the control device 1 of the engine. The present process is repeatedly performed mainly at the ECU 50 at predetermined timing.

  First, in step S100, it is determined whether a fuel cut condition is satisfied. The fuel cut conditions are as described above, and thus the detailed description is omitted here. Here, when the fuel cut condition is satisfied, the process proceeds to step S102. On the other hand, when the fuel cut condition is not satisfied, the process is temporarily left out.

  In step S102, the temperature Tcat of the exhaust purification catalyst 20 is estimated (acquired). The method of estimating the temperature Tcat of the exhaust purification catalyst 20 is as described above, and thus the detailed description is omitted here. Subsequently, in step S104, it is determined whether the estimated temperature Tcat of the exhaust purification catalyst 20 estimated in step S102 is higher than a predetermined temperature Tfc (for example, 600 to 700 ° C.). Here, when the estimated temperature Tcat of the exhaust purification catalyst 20 is higher than the predetermined temperature Tfc, the process proceeds to step S108. On the other hand, when the estimated temperature Tcat of the exhaust purification catalyst 20 is lower than or equal to the predetermined temperature Tfc, the process proceeds to step S106.

  In step S106, the driving of the injector 12 is stopped, and the fuel injection by the injector 12 is stopped (that is, the fuel cut is performed). After that, the process is temporarily left.

  On the other hand, in step S108, execution of fuel cut is prohibited in order to prevent deterioration of the exhaust purification catalyst 20. Then, in step S110, the transmission gear ratio of the continuously variable transmission 81 such that the actual engine speed coincides with a target engine speed (for example, about 1000 rpm) set to a higher speed side than the minimum engine speed Nmin. A shift request is output to the TCU 80 so as to change the to the low side. As a result, the transmission ratio of the continuously variable transmission 81 is shifted to the low side, and the engine speed is increased to the target speed (for example, increased by about 100 to 200 rpm).

  Subsequently, in step S112, based on the deviation between the intake air amount at the minimum engine speed Nmin and the intake air amount at the target engine speed (ie, the amount of fresh air taken into the engine 10 does not change And the EGR valve 42 is driven to increase the amount of exhaust gas recirculation. At this time, the opening degree of the throttle valve 13 is adjusted so that the same amount of fresh air as the amount of intake air at the minimum engine speed Nmin is drawn. After that, the process is temporarily left.

  As described above in detail, according to the present embodiment, when the temperature of the exhaust purification catalyst 20 becomes higher than the predetermined temperature Tfc and fuel cut is prohibited, the transmission ratio of the continuously variable transmission 81 is low. Change to the side. Therefore, the engine rotational speed is increased, and the engine friction is increased. Thus, the deceleration of the vehicle can be increased. On the other hand, when the fuel cut is prohibited, the amount of exhaust gas returned to the intake manifold 11 of the engine 10 is increased. Therefore, even if the engine rotational speed is increased, the increase of the fresh air drawn into the engine 10 is suppressed, and the increase of the fuel injection amount is suppressed. Thus, an increase in engine output can be suppressed. As a result, when the fuel cut is prohibited from the viewpoint of preventing the deterioration of the exhaust purification catalyst 20, it is possible to effectively prevent the deterioration of the feeling of deceleration (the feeling of free running) without deteriorating the fuel consumption. It becomes.

  At this time, according to the present embodiment, when execution of fuel cut is prohibited, the engine 10 is selected based on the deviation between the intake air amount at the minimum engine speed Nmin and the intake air amount at the target engine speed. The amount of exhaust gas recirculated to the intake manifold 11 is increased. Therefore, even if the engine speed has increased to the target speed, the amount of fresh air taken into the engine 10 is maintained at the same amount as the amount of intake air at the minimum engine speed Nmin, and the fuel injection amount increases. Be suppressed. Therefore, an increase in engine output can be appropriately suppressed.

  Further, according to the present embodiment, when the fuel cut is prohibited, the gear ratio of the continuously variable transmission 81 is low based on the target engine rotation speed set higher than the minimum engine rotation speed. Change to the side. Therefore, the engine speed can be increased to the target engine speed.

  In particular, according to the present embodiment, when the fuel cut is prohibited and the engine speed is increased, the amount of fresh air taken into the engine 10 is the same as the amount of intake air at the minimum engine speed Nmin. Thus, the throttle valve 13 is controlled, and the injector 12 is controlled such that the fuel injection amount is the same as the fuel injection amount at the minimum engine speed Nmin. Therefore, when the engine speed increases, an increase in engine output can be appropriately prevented.

  According to the present embodiment, the temperature of the exhaust purification catalyst 20 is estimated based on the engine speed, the engine load, the air-fuel ratio, and the ignition timing. Therefore, the temperature of the exhaust purification catalyst 20 can be accurately estimated without using a dedicated temperature sensor.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, in the above embodiment, the temperature of the exhaust purification catalyst 20 is estimated based on the engine speed, the engine load, the air-fuel ratio, and the ignition timing. However, for example, a temperature sensor such as a thermocouple is used to The temperature may be measured (detected).

  In the above embodiment, the present invention is applied to a cylinder injection type engine as an example, but the present invention can also be applied to a port injection type engine or the like. Furthermore, the present invention is not limited to horizontally opposed engines, and can be applied to, for example, engines such as in-line engines and V-type engines.

  In the above embodiment, the present invention is applied to a chain-type continuously variable transmission (CVT), but instead of the chain-type continuously variable transmission, for example, a belt-type continuously variable transmission or a toroidal stepless continuously variable transmission It can be applied to a transmission etc. Moreover, it may replace with a continuously variable transmission (CVT) and may apply to a stepped automatic transmission (AT).

DESCRIPTION OF SYMBOLS 1 Engine control system 10 Engine 11 Intake manifold 12 Injector 13 Electronic control type throttle valve 14 Air flow meter 17 Spark plug 19 Air-fuel ratio sensor (LAF sensor)
31 Throttle Opening Sensor 32 Cam Angle Sensor 33 Crank Angle Sensor 40 EGR Device 42 EGR Valve 50 ECU
Reference Signs List 51 fuel injection control unit 52 catalyst temperature acquisition unit 53 fuel cut prohibition unit 54 shift request unit 55 reflux amount control unit 56 throttle valve control unit 80 TCU
81 Continuously variable transmission

Claims (5)

Fuel injection control means for executing a fuel cut to stop fuel injection to the engine when a predetermined fuel injection stop condition is satisfied;
Catalyst temperature acquisition means for acquiring the temperature of an exhaust purification catalyst that purifies exhaust gas discharged from the engine;
Fuel cut inhibiting means for inhibiting execution of fuel cut by the fuel injection control means when the temperature of the exhaust gas purification catalyst acquired by the catalyst temperature acquisition means is higher than a predetermined temperature;
An exhaust gas recirculation device for recirculating a part of exhaust gas discharged from the engine to an intake system of the engine;
When the execution of fuel cut is prohibited by the fuel cut prohibiting means, the gear ratio of the automatic transmission that converts and outputs the driving force of the engine to the low side than when the fuel cut is performed Shift request means for requesting to change;
When the execution of the fuel cut is prohibited by the fuel cut prohibiting means, the exhaust gas is re-generated so as to increase the amount of exhaust gas to be recirculated to the intake system of the engine than when the fuel cut is performed. An engine control device comprising: a reflux amount control means for driving a circulation device.   When the execution of the fuel cut is prohibited, the reflux amount control means is configured to have an intake air amount at a minimum engine speed that can be operated in a state where the fuel cut is prohibited and a lower engine speed than the minimum engine speed. The engine control device according to claim 1, wherein the amount of exhaust gas recirculation is increased based on the deviation from the amount of intake air at a target engine rotational speed set on the high rotation side.   When the fuel cut is prohibited, the shift request means sets a target engine speed that is set higher than the minimum engine speed that can be operated in a state where the fuel cut is prohibited. The engine control device according to claim 1 or 2, wherein a change gear ratio of the automatic transmission is changed to a low side based on the change. Throttle valve control means for adjusting the amount of air taken into the engine according to the amount of operation of the accelerator pedal;
The throttle valve control means adjusts the throttle valve opening so that the same amount of fresh air as the amount of intake air at the minimum engine speed is drawn when execution of fuel cut is prohibited.
The fuel injection control means controls the injector so that the same amount of fuel as the fuel injection amount at the minimum engine speed is injected when execution of fuel cut is prohibited. The engine control device according to 2 or 3 .   The said catalyst temperature acquisition means estimates the temperature of the said exhaust gas purification catalyst based on an engine speed, an engine load, an air fuel ratio, and ignition timing, The any one of the Claims 1-4 characterized by the above-mentioned. Engine control device.

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