JP2007192061A - Control device and operation method for internal combustion engine - Google Patents

Abstract

To provide a control device and an operation method for an internal combustion engine capable of sufficiently purifying exhaust gas even when the operation state of the internal combustion engine shifts from an idle state to an acceleration state.
When an operation state shifts from a fuel cut state (step ST1) to an idle state (step ST2), an idling rich control for controlling the air-fuel ratio to a rich side is performed (step ST3), and an idling rich control is performed. Is calculated (step ST4), and if the integrated intake air amount S is greater than or equal to the predetermined air amount S1 (step ST5), the oxygen concentration V is acquired (step ST6) and acquired. When the oxygen concentration V exceeds the target oxygen concentration V1 (step ST7), the fuel supplied to the internal combustion engine is increased, and the increased fuel is supplied to the internal combustion engine (step ST8).
[Selection] Figure 2

Description

  The present invention relates to a control device and an operation method for an internal combustion engine, and more particularly to a control device and an operation method for an internal combustion engine that control an air-fuel ratio to a rich side when the operation state shifts from a fuel cut state to an idle state. .

  An internal combustion engine includes an exhaust gas purification catalyst (three-way catalyst) for purifying harmful substances contained in exhaust gas, such as nitride oxide (NOx), carbon monoxide (CO), and hydrocarbon (HC), in an exhaust path. It has been. When the operation state of the internal combustion engine is in a fuel cut state, only the oxygen passes through the exhaust gas purification catalyst, resulting in excessive oxygen. Further, when the operating state of the internal combustion engine is in the fuel cut state, the catalyst bed temperature of the exhaust gas purification catalyst is lowered because the temperature of the exhaust gas passing through the exhaust gas purification catalyst is low. Therefore, immediately after the operating state of the internal combustion engine shifts from the fuel cut state to the idle state, the purification ability of the exhaust gas purification catalyst decreases due to these.

Therefore, as shown in Patent Document 1, some conventional internal combustion engines perform idling rich control in which the air-fuel ratio is controlled to the rich side in order to eliminate excess oxygen and raise the catalyst bed temperature. The idling rich control by this conventional internal combustion engine is performed by, for example, supplying a certain amount of fuel to the internal combustion engine until the oxygen concentration detected by an O ₂ sensor arranged downstream of the exhaust gas purification catalyst becomes equal to or lower than the target oxygen concentration. Supply.

Japanese Patent Laid-Open No. 2005-69188

  FIGS. 5A and 5B are diagrams illustrating a state of a conventional exhaust gas purification catalyst. As shown in FIG. 5A, the exhaust gas purification catalyst 100 immediately before the start of the idling rich control is in a state where the catalyst bed temperature is low from the upstream side to the downstream side, and the entire catalyst lean state is excessive in oxygen. As shown in FIG. 5B, the exhaust gas purification catalyst 100 during the idling rich control is a catalyst on the exhaust side that passes through the exhaust gas purification catalyst 100 from the upstream side due to the rich side, that is, the fuel contained in the exhaust gas. The bed temperature rises, and the catalyst rich state with excessive fuel starts from the upstream side. That is, the exhaust gas purification catalyst 100 during the idling rich control has the upstream catalyst bed temperature higher than the downstream side, and the upstream purification capacity becomes lower than the downstream purification capacity.

Here, the oxygen concentration of the exhaust gas that has passed through the exhaust gas purification catalyst 100 exceeds the target oxygen concentration if the downstream side of the exhaust gas purification catalyst 100 during the idling rich control is in the catalyst lean state. Therefore, the O ₂ sensor 110 disposed on the downstream side of the exhaust gas purification catalyst 100 has an oxygen concentration exceeding the target oxygen concentration even when most of the O ₂ sensor 110 except for the downstream side of the exhaust gas purification catalyst 100 is in a catalyst rich state. Is detected. As a result, the control device for the internal combustion engine does not end the idling rich control even if most of the interior of the exhaust gas purification catalyst 100 is in the catalyst rich state, and supplies the above-mentioned constant amount of fuel to the internal combustion engine. To maintain.

  When the operation state of the internal combustion engine shifts from the idle state to the acceleration state during the idling rich control, the fuel supplied to the internal combustion engine increases. Accordingly, the exhaust gas containing a large amount of fuel passes through the exhaust gas purification catalyst 100. Here, during the idling rich control, as described above, the portion of the exhaust gas purification catalyst 100 that is in the catalyst lean state is only on the downstream side where the catalyst bed temperature is low, and thus the exhaust gas purification catalyst 100 as a whole is purified. Ability is reduced. Therefore, if the operating state of the internal combustion engine shifts from the idle state to the acceleration state during the idling rich control, it may be difficult to purify HC by the exhaust gas purification catalyst 100.

  The present invention has been made in view of the above, and a control device and an operation method for an internal combustion engine capable of sufficiently purifying exhaust gas even when the operation state of the internal combustion engine shifts from an idle state to an acceleration state. The purpose is to provide.

  In order to solve the above-described problems and achieve the object, according to the present invention, an internal combustion engine that performs rich control during idling that controls the air-fuel ratio to the rich side when the operating state shifts from the fuel cut state to the idle state. In the control device, an intake air amount integrating means for integrating the intake air amount from the start of the rich control at idle time, an oxygen concentration acquiring means for acquiring the oxygen concentration of the exhaust gas on the downstream side of the exhaust gas purification catalyst, Fuel supply control means for controlling the supply of fuel to the internal combustion engine, wherein the fuel supply control means is configured so that, during the idling rich control, the integrated cumulative intake air amount is greater than or equal to a predetermined air amount, and The fuel to be supplied is increased when the obtained oxygen concentration exceeds the target oxygen concentration.

  In the control apparatus for an internal combustion engine according to the present invention, the fuel supply amount control means maintains the increase in the supplied fuel until the acquired oxygen concentration is equal to or lower than a target oxygen concentration. And

  Further, in the present invention, when the operating state shifts from the fuel cut state to the idle state, an internal combustion engine that performs rich control during idling that controls the downstream side air-fuel ratio of the exhaust gas on the downstream side of the exhaust gas purification catalyst to the rich side In the operating method, the procedure for calculating the intake air amount from the start of the idling rich control, the procedure for obtaining the downstream air-fuel ratio, the integrated integrated intake air amount is not less than a predetermined air amount, and A step of increasing fuel supplied to the internal combustion engine when the acquired downstream air-fuel ratio is on the lean side; and a step of supplying the increased fuel to the internal combustion engine. .

  According to these inventions, when the operating state shifts from the fuel cut state to the idle state, the control device for the internal combustion engine has the integrated cumulative intake air amount equal to or greater than the predetermined air amount, that is, most of the exhaust gas purification catalyst. When the operating state of the internal combustion engine shifts from the idle state to the acceleration state, it becomes impossible to sufficiently purify HC, and if the acquired oxygen concentration exceeds the target oxygen concentration, The fuel supplied to the engine is increased, and the oxygen concentration acquired early is set below the target oxygen concentration. When the acquired oxygen concentration falls below the target oxygen concentration, the control device for the internal combustion engine ends the idle rich control, starts feedback control based on the acquired oxygen concentration and the target oxygen concentration, and supplies it to the internal combustion engine. Reduce the amount of fuel used from a certain amount. Therefore, the exhaust gas purifying catalyst is in a catalyst lean state with excess oxygen on the upstream side while the catalyst bed temperature is increased from the upstream side. As a result, the exhaust gas purification catalyst can recover the reduced purification capability by ending the rich control at idling early, and even if the operating state of the internal combustion engine shifts from the idle state to the acceleration state, the exhaust gas purification catalyst The gas can be sufficiently purified.

  In the control apparatus for an internal combustion engine according to the present invention, the predetermined air amount is reduced as the catalyst bed temperature of the exhaust gas purification catalyst is lower.

  Here, when the catalyst bed temperature is low, the purification capability of the exhaust gas purification catalyst decreases. In other words, when the exhaust gas purification catalyst has a low catalyst bed temperature and most of the exhaust gas purification catalyst is in a catalyst rich state, it becomes more difficult to sufficiently purify HC. However, according to the present invention, the lower the catalyst bed temperature of the exhaust gas purification catalyst, the smaller the predetermined air amount, that is, the smaller the portion of the exhaust gas purification catalyst that becomes catalyst rich. Therefore, the control device for the internal combustion engine can finish the idling rich control at an early stage before the exhaust gas purification catalyst cannot sufficiently purify HC. As a result, the exhaust gas purification catalyst can reliably purify the exhaust gas even when the operating state of the internal combustion engine shifts from the idle state to the acceleration state.

  Since the control device and the operation method for the internal combustion engine according to the present invention finish the idling rich control early and recover the reduced purification ability, even if the operation state of the internal combustion engine shifts from the idle state to the acceleration state, Exhaust gas can be sufficiently purified.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the following Example. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  FIG. 1 is a diagram showing a configuration example of an internal combustion engine according to an embodiment of the present invention. As shown in the figure, an internal combustion engine 1 according to this embodiment includes a fuel supply device 2, an internal combustion engine body 3 including a plurality of cylinders 30a to 30d (in this embodiment, in-line four cylinders), an internal combustion engine, and the like. An intake path 5 connected to the engine body 3, an exhaust path 6 connected to the internal combustion engine body 3, and an ECU (Engine Control Unit) 7 that is a control device that controls the operation of the internal combustion engine 1. Yes.

  The fuel supply device 2 supplies the fuel stored in the fuel tank 22, such as gasoline, to the internal combustion engine 1. The fuel supply device 2 includes a fuel injection valve 21, a fuel tank 22, a low-pressure fuel pump 23, and a fuel supply pipe.

  The fuel injection valve 21 is provided for each of the cylinders 30a to 30d of the internal combustion engine body 3, and for example, injects fuel pressurized by the low pressure fuel pump 23 into the intake port 37 of each of the cylinders 30a to 30d. It is. The ECU 7 performs control of the fuel injection amount of the fuel injection valve 21, that is, the fuel supply amount of the fuel supplied to the internal combustion engine 1 and the injection timing, that is, fuel injection control.

  The internal combustion engine body 3 includes a cylinder block 31, a cylinder head 32 fixed to the cylinder block 31, a piston 33 and a connecting rod 34 provided for each of the cylinders 30a to 30d, a crankshaft 35, and each of the cylinders 30a to 30d. The ignition plug 36 and the valve device 4 are provided. Here, in each of the cylinders 30 a to 30 d of the internal combustion engine body 3, a combustion chamber A is formed by the piston 33, the cylinder block 31, and the cylinder head 32 of each of the cylinders 30 a to 30 d. In the cylinder head 32, an intake port 37 and an exhaust port 38 are formed for each of the cylinders 30a to 30d, and are connected to the intake path 5 and the exhaust path 6, respectively. The piston 33 is rotatably supported by a connecting rod 34, and the connecting rod 34 is rotatably supported by a crankshaft 35. In other words, the crankshaft 35 rotates as the piston 33 reciprocates in the cylinder block 31 as the mixed gas of the intake air and fuel in the combustion chamber A burns.

  The spark plug 36 is provided for each of the cylinders 30a to 30d, and is ignited by an ignition signal from the ECU 7 to ignite the mixed gas in the combustion chamber A of each cylinder 30a to 30d. Control such as the ignition timing of the spark plug 36, that is, ignition control is performed by the ECU 7. Reference numeral 39 denotes a crank angle sensor that detects a crank angle (CA) that is an angle of the crankshaft 35 and outputs the detected crank angle (CA) to the ECU 7. The ECU 7 determines the engine speed of the direct injection internal combustion engine 1-1 and the cylinders 30a to 30d from the crank angle detected by the crank angle sensor 39.

  The valve device 4 opens and closes the intake valve 41 and the exhaust valve 42. The valve device 4 includes an intake valve 41 and an exhaust valve 42 provided for each of the cylinders 30a to 30d, an intake camshaft 43, an exhaust camshaft 44, and an intake valve timing mechanism 45. The intake valve 41 is disposed between the intake port 37 and the combustion chamber A, and is opened and closed as the intake camshaft 43 rotates. The exhaust valve 42 is disposed between the exhaust port 38 and the combustion chamber A, and is opened and closed as the exhaust camshaft 44 rotates. The intake camshaft 43 and the exhaust camshaft 44 are connected to a crankshaft 35 through a timing chain, and rotate in conjunction with the rotation of the crankshaft 35.

  The intake valve timing mechanism 45 is disposed between the intake camshaft 43 and the crankshaft 35. The intake valve timing mechanism 45 is a continuously variable valve timing mechanism that continuously changes the phase of the intake camshaft 43. Further, the valve device 4 is provided with an intake cam position sensor 46, which detects the rotational position of the intake cam shaft 43 and outputs it to the ECU 7. The valve device 4 adjusts the opening / closing timing of the intake valve 41 by the intake valve timing mechanism 45. However, the present invention is not limited to this. For example, an exhaust valve timing mechanism for adjusting the opening / closing timing of the exhaust valve 42 is provided. You may prepare.

  The intake path 5 takes in air from the outside and introduces the introduced air into the combustion chamber A of each cylinder 30 a to 30 d of the internal combustion engine body 3. The intake path 5 includes an air cleaner 51, an air flow meter 52, a throttle valve 53, and an intake path 54 that communicates from the air cleaner 51 to the intake ports 37 of the cylinders 30a to 30d. The air from which the dust has been removed by the air cleaner 51 is introduced into the combustion chambers A of the cylinders 30a to 30d via the intake passage 54 and the intake port 37. The air flow meter 52 detects the amount of intake air introduced into each cylinder 30a to 30d, that is, sucked air, and outputs it to the ECU 7. The throttle valve 53 is driven by an actuator 53a such as a stepping motor, and adjusts the amount of intake air taken into the combustion chamber A of each cylinder 30a-d. The control of the opening degree of the throttle valve 53, that is, the throttle valve opening degree control is performed by the ECU 7.

The exhaust path 6 includes a purification catalyst 61, a silencer (not shown), an exhaust passage 62 communicating from the exhaust port 38 of each cylinder 30a to 30d to the silencer via the exhaust gas purification catalyst 61, and an A / F. The sensor 63 and the O ₂ sensor 64 are configured. The exhaust gas purification catalyst 61 purifies harmful substances such as nitrided oxide (NOx), carbon monoxide (CO), and hydrocarbon (HC) contained in the exhaust gas introduced through the exhaust passage 62. . The exhaust gas from which the harmful substances have been purified is exhausted from the exhaust gas purification catalyst 61 to the outside through an exhaust passage and a silencer (not shown).

  The A / F sensor 63 is disposed upstream of the exhaust gas purification catalyst 61 in the exhaust passage 62. The A / F sensor 63 detects the exhaust gas air-fuel ratio of the exhaust gas before being introduced into the exhaust gas purification catalyst 61 out of the exhaust gas exhausted from each combustion chamber A to the exhaust path 6, and outputs it to the ECU 7. To do. The air-fuel ratio detected by the A / F sensor 63 is used to control the air-fuel ratio of the mixed gas composed of intake air and fuel.

The O ₂ sensor 64 is disposed on the downstream side of the exhaust gas purification catalyst 61 in the exhaust passage 62. The O ₂ sensor 64 detects the oxygen concentration of the exhaust gas that has passed through the exhaust gas purification catalyst 61 out of the exhaust gas exhausted from each combustion chamber A to the exhaust path 6 and outputs it to the ECU 7. The oxygen concentration detected by the O ₂ sensor 64 is mainly used to control the state of the exhaust gas purification catalyst 61, for example, the oxygen storage amount.

The ECU 7 operates the internal combustion engine 1 by controlling the operation of the internal combustion engine 1. The ECU 7 receives various input signals from sensors attached to various parts of the vehicle on which the internal combustion engine 1 is mounted. Specifically, the crank angle detected by the crank angle sensor 39 attached to the crankshaft 35, the intake air amount detected by the air flow meter 52, the accelerator opening detected by the accelerator pedal sensor 8, the A / F sensor The upstream air-fuel ratio detected by 63, the oxygen concentration detected by the O ₂ sensor 64, the temperature of cooling water for cooling the internal combustion engine, and the like.

  The ECU 7 outputs various output signals based on these input signals and various maps such as a fuel injection amount map based on the intake air amount and the accelerator opening stored in the storage unit 73. Specifically, these are output signals such as an injection signal for performing fuel injection control of the fuel injection valve 21, an ignition signal for performing ignition control of the spark plug 36, and a throttle valve opening signal for controlling the throttle valve opening of the throttle valve 53. .

  The ECU 7 includes an input / output unit (I / O) 71 that inputs and outputs the input signal and output signal, a processing unit 72, and a storage unit 73 that stores various maps such as a fuel injection amount map. Has been. The processing unit 72 includes a memory and a CPU (Central Processing Unit). The processing unit 72 includes at least an intake air amount integration unit 74 that is an intake air amount integration unit, an oxygen concentration acquisition unit 75 that is an oxygen concentration acquisition unit, and a fuel injection control unit 76 that is a fuel supply control unit. And a memory and a CPU (Central Processing Unit). The processing unit 72 may realize the operation method of the internal combustion engine 1 by loading a program based on the operation method of the internal combustion engine 1 into a memory and executing the program. The storage unit 73 is a non-volatile memory such as a flash memory, a non-volatile memory such as a ROM (Read Only Memory) that can only be read, or a volatile that can be read and written such as a RAM (Random Access Memory). The memory can be configured by a combination of these, or a combination thereof.

  Next, a method for operating the internal combustion engine 1 according to the embodiment will be described. FIG. 2 is a diagram illustrating an operation flow of the operation method of the internal combustion engine according to the embodiment. FIG. 3 is a diagram showing an operating state of the internal combustion engine. FIG. 4 is a view showing a state of the exhaust gas purification catalyst. First, as shown in FIG. 2, the processing unit 72 of the ECU 7 determines whether or not the operating state of the internal combustion engine 1 is a fuel cut state (step ST1). Here, the fuel cut state refers to a state in which fuel injection by the fuel injection valve 21 is stopped. As shown in FIG. 3, this fuel cut state occurs when, for example, the accelerator pedal is released and the accelerator opening decreases or becomes zero. In this fuel cut state, as shown in the figure, the fuel cut flag changes from OFF to ON. In the fuel cut state, the vehicle on which the internal combustion engine 1 according to the normal embodiment is mounted decelerates and stops. In addition, the process part 72 repeats said step ST1 until the driving | running state of the internal combustion engine 1 will be in a fuel cut state.

  Next, as illustrated in FIG. 2, when the processing unit 72 of the ECU 7 determines that the operating state of the internal combustion engine 1 is a fuel cut state, the processing unit 72 determines whether or not the operating state of the internal combustion engine 1 has become an idle state. (Step ST2). That is, the processing unit 72 determines whether or not the operating state of the internal combustion engine 1 has shifted from the fuel cut state to the idle state. Here, the idle state refers to a state in which the internal combustion engine 1 is maintained at a low speed (for example, about 400 to 800 rpm). As shown in FIG. 3, this idle state is generated when the accelerator pedal is released, the accelerator opening becomes 0, and the vehicle equipped with the internal combustion engine 1 according to the first embodiment stops. is there. In this idle state, as shown in the figure, the idle flag changes from OFF to ON. Note that the fuel cut flag is switched from ON to OFF before the idle flag is switched from OFF to ON. Moreover, the process part 72 repeats said step ST1, ST2 until the driving | running state of the internal combustion engine 1 transfers to an idle state from an idle fuel cut state.

  Next, as shown in FIG. 2, when the processing unit 72 determines that the operating state of the internal combustion engine 1 has become an idle state, the fuel injection control unit 76 of the processing unit 72 starts rich control during idling (step ST3). ). Here, the fuel injection control unit 76 starts the idling rich control in the fuel injection control. That is, when the engine enters the idle state, the fuel injection valve 21 starts fuel injection with the fuel injection amount Q = Q1, and starts supplying fuel to the internal combustion engine 1. The fuel injection amount Q1 is determined based on the detected intake air amount so that the air-fuel ratio is richer than the stoichiometric air-fuel ratio.

  Next, the intake air amount integration unit 74 of the processing unit 72 starts the integration of the intake air amount from the start of the idling rich control by the fuel injection control unit 76 (step ST4). Here, the intake air amount integration unit 74 acquires the intake air amount detected by the air flow meter 52 and output to the ECU 7, and sequentially integrates it.

  Next, the intake air amount integration unit 74 of the processing unit 72 determines whether or not the integrated intake air amount S is equal to or greater than a predetermined air amount S1 (step ST5). Here, the predetermined air amount S1 means that the HC is sufficiently purified when the exhaust gas purification catalyst 61 is mostly in the catalyst rich state and the operating state of the internal combustion engine 1 shifts from the idle state to the acceleration state. This is the cumulative intake air volume that cannot be achieved. Therefore, the intake air amount calculation unit 74 determines whether or not the exhaust gas purification catalyst 61 has been unable to sufficiently purify HC during the idling rich control. The intake air amount integration unit 74 continues to integrate the acquired intake air amount until the integrated intake air amount S becomes equal to or greater than the predetermined air amount S1 (step ST4).

  Next, the oxygen concentration acquisition unit 75 of the processing unit 72 acquires the oxygen concentration V (step ST6). Here, the oxygen concentration V of the exhaust gas that has passed through the exhaust gas purification catalyst 61 detected by the oxygen concentration acquisition unit 74 is acquired.

  Next, the oxygen concentration acquisition unit 75 of the processing unit 72 determines whether or not the acquired oxygen concentration V exceeds the target oxygen concentration V1, that is, whether or not V> V1 (step ST7). Here, the target oxygen concentration V1 is, for example, 0. This is because, when the exhaust gas purification catalyst 61 has a sufficient purification capability for the exhaust gas, oxygen contained in the exhaust gas is all used in the exhaust gas purification catalyst 61 when purifying the exhaust gas. It is.

  Next, the fuel injection control unit 76 of the processing unit 72 causes the oxygen concentration V acquired by the oxygen concentration acquisition unit 75 to exceed the target oxygen concentration V1, that is, the exhaust gas on the downstream side of the exhaust gas purification catalyst 61 contains oxygen. If it is determined, the fuel supplied to the internal combustion engine 1 is increased (step ST8). Here, the fuel injection control unit 76 injects into the internal combustion engine 1 by the fuel injection valve 21 from T2 when the oxygen concentration V exceeds the target oxygen concentration V1 and the integrated intake air amount S is equal to or greater than the predetermined air amount S1. The fuel injection amount Q is increased from Q1 to Q2 (Q2> Q1), the fuel injection of the increased fuel injection amount Q2 is started, and the fuel is supplied to the internal combustion engine 1. Then, the fuel injection control unit 76 determines that the oxygen concentration V acquired by the oxygen concentration acquisition unit 75 is equal to or less than the target oxygen concentration V1, that is, the exhaust gas downstream of the exhaust gas purification catalyst 61 does not contain oxygen. Until this is done, fuel injection of the fuel injection amount Q2 is maintained, and the increased fuel supply to the internal combustion engine 1 is maintained.

  As a result, as shown in FIG. 3, when the integrated intake air amount S is equal to or greater than the predetermined air amount S1 and the oxygen concentration V exceeds the target oxygen concentration V1, the fuel supplied to the internal combustion engine 1 is increased. When this is done (B in the figure), the oxygen concentration V of the exhaust gas on the downstream side of the exhaust gas purification catalyst 61 is reduced to the target oxygen concentration V1 earlier than in the conventional case (C in the same figure). be able to. That is, when the fuel supplied to the internal combustion engine 1 is increased, the idling rich control can be completed earlier than in the conventional case where the fuel is not increased.

  Next, when it is determined that the oxygen concentration V acquired by the oxygen concentration acquiring unit 75 is equal to or lower than the target oxygen concentration V1, the fuel injection control unit 76 of the processing unit 72 ends the idling rich control (step ST9). ). Then, the fuel injection control unit 76 ends the idling rich control, and starts feedback control based on the acquired oxygen concentration V and the target oxygen concentration V1. That is, the fuel injection control unit 76 reduces the fuel injection amount Q from the fuel injection amount Q2 to the fuel injection amount Q3 smaller than the fuel supply amount Q1 from T3 when the idling rich control is finished, Supply. Thereafter, the fuel injection control unit 76 performs feedback control, that is, normal idle control, for the fuel supplied to the internal combustion engine 1 so that the acquired oxygen concentration V becomes the target oxygen concentration V1.

  Immediately after the fuel injection control unit 76 of the processing unit 72 completes the idling rich control and shifts to the normal idle control, as shown in FIG. 4, the exhaust gas purification catalyst 61 has a catalyst bed temperature rising from the upstream side. In this state, the upstream side becomes a catalyst lean state with excessive oxygen. The exhaust gas purifying catalyst 61 in such a state can recover the purification ability because the downstream side catalyst bed temperature is low and the downstream side becomes higher than the purification ability in the catalyst lean state where the oxygen is excessive. In other words, the reduced purification ability can be recovered early by ending the rich control at idle early.

  From the above, in the control apparatus for an internal combustion engine according to the present invention, as shown in FIG. 3, the idling rich control can be completed earlier than the conventional control apparatus for an internal combustion engine. When the operating state shifts from the idle state to the accelerated state, the normal idle control can be shifted at T4. Therefore, in the internal combustion engine 1 according to the present invention, since the exhaust gas purification catalyst 61 can sufficiently purify HC, the amount of HC contained in the exhaust gas that has passed through the exhaust gas purification catalyst 61 is reduced to that of the conventional internal combustion engine (same as the above). Compared with FIG. E), it can be sufficiently purified (FIG. D). Thereby, even if the operation state of the internal combustion engine 1 shifts from the idle state to the acceleration state, the exhaust gas can be sufficiently purified.

  The exhaust gas purification catalyst 61 has a purification capacity that varies depending on the catalyst bed temperature. For example, the purification capacity of the exhaust gas purification catalyst 61 decreases when the catalyst bed temperature is low. In other words, when the idling rich control is performed in a state where the catalyst bed temperature of the exhaust gas purification catalyst 61 is low and most of the exhaust gas purification catalyst 61 is in the catalyst rich state, it becomes more difficult to sufficiently purify HC. There is a fear. Therefore, in the above embodiment, the predetermined air amount may be decreased as the catalyst bed temperature of the exhaust gas purification catalyst 61 is lower. Specifically, the intake air amount integrating unit 74 of the processing unit 72 acquires the coolant temperature that affects the catalyst bed temperature, and is low if the catalyst bed temperature predicted from the acquired water temperature is low. As a result, the predetermined air amount may be reduced.

  As described above, in the control apparatus for an internal combustion engine according to the present invention, the portion of the exhaust gas purification catalyst 61 that is in the catalyst rich state by decreasing the predetermined air amount as the catalyst bed temperature of the exhaust gas purification catalyst is lower. Reduce. Therefore, before the exhaust gas purification catalyst 61 can sufficiently purify the HC, the idling rich control can be finished early. As a result, the exhaust gas purification catalyst 61 can reliably purify the exhaust gas even when the operating state of the internal combustion engine 1 shifts from the idle state to the acceleration state.

  The catalyst bed temperature of the exhaust gas purification catalyst 61 may be obtained directly from the catalyst bed temperature of the exhaust gas purification catalyst 61. Further, the catalyst bed temperature may be predicted by acquiring the intake air temperature of the intake air amount that affects the catalyst bed temperature instead of the coolant temperature.

  As described above, the control device and the operation method for the internal combustion engine according to the present invention are useful when performing the rich control during idling, and in particular, even if the operation state of the internal combustion engine shifts from the idle state to the acceleration state, Suitable for fully purifying exhaust gas.

It is a figure which shows the structural example of the internal combustion engine concerning the Example of this invention. It is a figure which shows the operation | movement flow of the operating method of the internal combustion engine concerning an Example. It is a figure which shows the driving | running state of an internal combustion engine. It is a figure which shows the state of an exhaust-gas purification catalyst. It is a figure which shows the state of the conventional exhaust gas purification catalyst. It is a figure which shows the state of the conventional exhaust gas purification catalyst.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Fuel supply apparatus 21 Fuel injection valve 22 Fuel tank 23 Low pressure fuel pump 3 Internal combustion engine main body 30a-d Cylinder 31 Cylinder block 32 Cylinder head 33 Piston 34 Connecting rod 35 Crankshaft 36 Spark plug 37 Intake port 38 Exhaust port 39 Crank Angle sensor 4 Valve device 41 Intake valve 42 Exhaust valve 43 Intake cam shaft 44 Exhaust cam shaft 45 Intake valve timing mechanism 46 Intake cam position sensor 5 Intake path 51 Air cleaner 52 Air flow meter 53 Throttle valve 6 Exhaust path 61 Exhaust gas purification catalyst 62 Exhaust Passage 63 A / F sensor 64 O ₂ sensor 7 ECU
71 Input / output unit 72 Processing unit 73 Storage unit 74 Intake air amount integration unit (intake air amount integration means)
75 Oxygen concentration acquisition unit (oxygen concentration acquisition means)
76 Fuel injection control unit (fuel supply control means)
8 Accelerator pedal sensor

Claims (4)

In the control device for an internal combustion engine that performs rich control during idling that controls the air-fuel ratio to the rich side when the operating state shifts from the fuel cut state to the idle state,
Intake air amount integration means for integrating the intake air amount from the start of the idling rich control;
Oxygen concentration acquisition means for acquiring the oxygen concentration of the exhaust gas on the downstream side of the exhaust gas purification catalyst;
Fuel supply control means for controlling the supply of fuel to the internal combustion engine;
With
The fuel supply control means supplies the fuel to be supplied when the integrated cumulative intake air amount is equal to or greater than a predetermined air amount and the acquired oxygen concentration exceeds a target oxygen concentration during the idling rich control. A control device for an internal combustion engine characterized by increasing.   2. The control device for an internal combustion engine according to claim 1, wherein the predetermined air amount is decreased as the catalyst bed temperature of the exhaust gas purification catalyst is lower.   3. The control of the internal combustion engine according to claim 1, wherein the fuel supply amount control means maintains the increase of the supplied fuel until the acquired oxygen concentration becomes equal to or lower than a target oxygen concentration. apparatus. In the operation method of the internal combustion engine that performs rich control at idling that controls the air-fuel ratio to the rich side when the operation state shifts from the fuel cut state to the idle state,
A procedure for calculating an intake air amount from the start of the idling rich control;
Obtaining the oxygen concentration;
A procedure for increasing the amount of fuel supplied to the internal combustion engine when the integrated cumulative intake air amount is equal to or greater than a predetermined air amount and the acquired oxygen concentration exceeds a target oxygen concentration;
Supplying the increased fuel to the internal combustion engine;
A method for operating an internal combustion engine comprising:

Images