JP7580889B2 - Control device for internal combustion engine - Google Patents

Description

The present invention relates to a control device that controls the operation of an internal combustion engine mounted on a vehicle, etc.

Internal combustion engines have traditionally been equipped with a fuel vapor emission suppression device that captures fuel vapor that has evaporated in the fuel tank (see, for example, the following patent document). A common fuel vapor emission suppression device is called a charcoal canister, and captures the generated fuel vapor by adsorbing it in a canister filled with activated charcoal, and then sends the fuel vapor to the intake passage of the internal combustion engine at the appropriate time to mix it with the intake air and combust it in the cylinder.

The canister is connected to a recovery passage for recovering fuel vapor in the fuel tank, an atmosphere introduction passage open to the atmosphere, and a purge gas passage that connects the canister to the intake passage of the internal combustion engine downstream of the throttle valve. In the process of purging the fuel vapor adsorbed in the canister, a control valve provided on the purge gas passage is opened, and the intake negative pressure generated downstream of the throttle valve is used to draw in outside air into the canister while drawing the fuel vapor into the intake passage.

JP 2019-044669 A

When performing canister purging, it is desirable to estimate (or learn) the concentration of fuel components contained in the purge gas flowing into the intake passage through the purge gas flow passage, and adjust the opening of the control valve accordingly, thereby increasing or decreasing the flow rate of the purge gas.

However, it is not always possible to accurately estimate the concentration of purge gas. Immediately after starting the internal combustion engine, the estimation error can be large, which can cause significant disruptions to the air-fuel ratio of the mixture that fills the cylinders. Deviations in the air-fuel ratio can lead to fluctuations in engine torque (and even vibrations in the vehicle body) due to instability in the combustion of the mixture, and can also be a factor in increased emissions of harmful substances.

Setting the opening of the control valve small and limiting the flow rate of purge gas released into the intake passage can suppress the disturbance of the air-fuel ratio caused by the purging process. However, this creates a tradeoff in that the fuel vapor stored in the canister cannot be purged quickly.

The present invention was developed with the above points in mind, and its intended purpose is to suppress disturbances in the air-fuel ratio of the mixture while enabling rapid purging when a large amount of fuel vapor remains in the canister.

In the present invention, an internal combustion engine equipped with a fuel evaporative emission control device is controlled, the device comprising: a connecting passage connected to a fuel tank, a canister that captures fuel vapor generated in the fuel tank and flowing through the connecting passage, an inlet passage connected to the canister and capable of introducing air, a purge gas flow passage that connects the canister to an intake passage connected to a cylinder of the internal combustion engine and releases purge gas containing the fuel vapor captured in the canister into the intake passage, and a control valve that opens and closes the purge gas flow passage. After the internal combustion engine is started, the control valve is opened to an opening smaller than the maximum opening in order to release the purge gas into the intake passage, the concentration of fuel components in the purge gas flowing through the purge gas flow passage is estimated, and when the cumulative flow rate of the purge gas that has flowed through the purge gas flow passage exceeds a predetermined amount and the concentration of the fuel components in the purge gas exceeds a threshold value and is rich , the opening of the control valve when the control valve is subsequently opened is made larger than when this is not the case.

The present invention makes it possible to quickly purge a large amount of fuel vapor remaining in the canister while suppressing disturbances in the air-fuel ratio of the mixture.

1 is a diagram showing a schematic configuration of a vehicle internal combustion engine and a control device according to an embodiment of the present invention; FIG. 4 is a timing chart showing the contents of air-fuel ratio feedback control with reference to the output signal of an air-fuel ratio sensor upstream of the catalyst. FIG. 13 is a diagram illustrating the relationship between the correction amount FACF and the delay times TDR and TDL. FIG. 4 is a timing chart showing the contents of air-fuel ratio feedback control with reference to the output signal of an air-fuel ratio sensor downstream of the catalyst. 2 is a flowchart showing an example of a procedure of a process executed by the control device for the internal combustion engine according to a program of the embodiment; 2 is a timing chart showing a control process performed by the internal combustion engine control device according to the embodiment;

One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an overview of an internal combustion engine for a vehicle in this embodiment. The internal combustion engine in this embodiment is a spark-ignition four-stroke gasoline engine, and is equipped with multiple cylinders 1 (one of which is shown in FIG. 1). An injector 11 for injecting fuel is provided near the intake port of each cylinder 1. In addition, an ignition plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The ignition plug 12 generates a spark discharge between a center electrode and a ground electrode when an induced voltage generated by an ignition coil is applied to the ignition plug 12.

The intake passage 3 leads to the intake port of each cylinder 1, and distributes air taken in from the outside toward each cylinder 1, supplying it to the cylinder 1. An air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from upstream on the intake passage 3.

The internal combustion engine is equipped with a fuel vapor emission control device 6. The fuel vapor emission control device 6 captures the fuel vapor that has evaporated in the fuel tank 7 by adsorbing it in a charcoal canister 61 filled with activated charcoal, and then sends the fuel vapor to the intake passage 3 at the appropriate time to mix it with the intake air and combust it in the cylinder 1.

The fuel tank 7 and the canister 61 are connected via a connection passage 62. Fuel vapor generated in the fuel tank 7 flows into the canister 61 through the connection passage 62. The canister 61 and the intake passage 3 (particularly the surge tank 33, the intake manifold 34, or the intake port) are connected via a purge gas passage 63. The fuel vapor captured by the canister 61 flows into the intake passage 3 through the purge gas passage 63. In addition, the canister 61 is provided with an air introduction passage 64 that is open to the atmosphere.

On the purge gas flow passage 63, there is a purge VSV (Vacuum Switching Valve) 65, which is a control valve that opens and closes the flow passage 63. While the VSV 65 is open, the canister 61 and the intake passage 3 are connected via the purge gas flow passage 63. Then, the negative intake pressure generated downstream of the throttle valve 32 in the intake passage 3 draws the fuel vapor in the canister 61 into the intake passage 3. At this time, air, i.e., outside air, is taken into the canister 61 through the inlet passage 64.

The exhaust passage 4 starts from the exhaust port of each cylinder 1, and circulates the combustion gas generated by burning fuel in each cylinder 1 and leads it to the outside. An exhaust manifold 42 and a three-way catalyst 41 for purifying the exhaust are arranged in the exhaust passage 4. The catalyst 41 induces an oxidation/reduction reaction of harmful substances such as HC, CO, and _NOx to render them harmless.

Air-fuel ratio sensors 43 and 44 for detecting the air-fuel ratio of the gas flowing through the exhaust passage 4 are installed upstream and downstream of the catalyst 41 in the exhaust passage 4. The air-fuel ratio sensors 43 and 44 may be linear A/F sensors having output characteristics proportional to the air-fuel ratio of the exhaust gas, or _O2 sensors having output characteristics nonlinear with respect to the air-fuel ratio of the exhaust gas. In this embodiment, a linear A/F sensor is assumed as the air-fuel ratio sensor 43 upstream of the catalyst 41, and an _O2 sensor is assumed as the air-fuel ratio sensor 44 downstream of the catalyst 41. The output voltage f of the linear A/F sensor 43 becomes higher as the air-fuel ratio of the gas flowing into the catalyst 41 becomes leaner. On the other hand, the output voltage g of the _O2 sensor 44 becomes lower as the air-fuel ratio of the gas flowing out of the catalyst 41 becomes leaner. In particular, in a certain range near the stoichiometric air-fuel ratio, the rate of change of output with respect to the air-fuel ratio shows a large and steep gradient, and in a region where the air-fuel ratio is leaner than that, the rate of change of output asymptotically approaches a lower saturation value, and in a region where the air-fuel ratio is richer than that, the rate of change of output asymptotically approaches a higher saturation value, forming a so-called Z-characteristic curve. Incidentally, a further catalyst (not shown) for purifying exhaust gas may be provided downstream of the catalyst 41 and the air-fuel ratio sensor 44 in the exhaust passage 4.

The exhaust gas recirculation device 2 includes an external EGR passage 21 that connects the exhaust passage 4 and the intake passage 3, an EGR cooler 22 provided on the EGR passage 21, and an EGR valve 23 that opens and closes the EGR passage 21 to control the flow rate of EGR gas flowing through the EGR passage 21. The inlet of the EGR passage 21 is connected to a location downstream of the catalyst 41 in the exhaust passage 4. The outlet of the EGR passage 21 is connected to a location downstream of the throttle valve 32 in the intake passage 3 (in particular, the surge tank 33 or the intake manifold 34).

The ECU (Electronic Control Unit) 0, which is the control device for the internal combustion engine in this embodiment, is a microcomputer system having a processor, memory, an input interface, an output interface, etc. The ECU 0 may be configured by connecting multiple ECUs or controllers so that they can communicate with each other via an electric communication line such as a CAN (Controller Area Network).

The input interface of the ECU0 includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from a crank angle sensor that detects the rotation angle of the crankshaft of the internal combustion engine and the engine speed, an accelerator opening signal c output from a sensor that detects the amount of depression of the accelerator pedal by the driver or the opening of the throttle valve 32 as the accelerator opening (in other words, the engine torque or engine load rate required for the internal combustion engine), and a signal downstream of the throttle valve 32 in the intake passage 3 (particularly, The following signals are input: intake air temperature/intake pressure signal d output from a temperature/pressure sensor that detects the intake air temperature and intake pressure in the intake tank 33 or intake manifold 34; a cooling water temperature signal e output from a water temperature sensor that detects the cooling water temperature of the internal combustion engine; an air-fuel ratio signal f output from an air-fuel ratio sensor 43 that detects the air-fuel ratio of the exhaust gas upstream of the catalyst 41 in the exhaust passage 4; an air-fuel ratio signal g output from an air-fuel ratio sensor 44 that detects the air-fuel ratio of the exhaust gas downstream of the catalyst 41; and an atmospheric pressure signal h output from an atmospheric pressure sensor that detects the atmospheric pressure.

The output interface of ECU0 outputs an ignition signal i to the igniter 13 of the spark plug 12, a fuel injection signal j to the injector 11, an opening operation signal k to the throttle valve 32, an opening operation signal l to the EGR valve 23, an opening operation signal n to the VSV 65, etc.

The processor of ECU0 interprets and executes programs stored in memory in advance, and calculates operating parameters to control the operation of the internal combustion engine. ECU0 acquires various pieces of information a, b, c, d, e, f, g, and h necessary for controlling the operation of the internal combustion engine via the input interface, and determines the engine speed and estimates the amount of air (fresh air) drawn into cylinder 1. Then, based on the engine speed and intake air amount, etc., it determines various operating parameters such as the required fuel injection amount, fuel injection timing (including the number of fuel injections per combustion), fuel injection pressure, required EGR rate (or EGR gas amount), ignition timing (including the number of spark ignitions per combustion), etc. ECU0 applies various control signals i, j, k, l, and n corresponding to the operating parameters via the output interface.

When determining the amount of fuel injected from the injector 11, the ECU 0 first calculates the amount of air taken into the cylinder 1, and then determines the basic amount of fuel injection TP that is proportional to the amount of intake air (so that an air-fuel ratio equal to or close to the theoretical air-fuel ratio can be achieved depending on the amount of intake air). The amount of intake air is estimated based on the current engine speed and intake pressure (in the surge tank 33 or intake manifold 34), etc. The estimated value of the amount of intake air may be corrected according to the current intake temperature, atmospheric pressure, etc. This method of estimating the amount of intake air is well known.

Next, this basic injection amount TP is corrected by a feedback correction coefficient FAF corresponding to the deviation between the air-fuel ratio of the gas flowing into the catalyst 41 and its target value, and various correction coefficients K determined according to environmental conditions and the like. The feedback correction coefficients FAF and K are each a positive number that increases or decreases around 1. Furthermore, the final fuel injection time T, i.e., the time for which the injector 11 is opened, is calculated taking into account the invalid injection time TAUV during which no fuel is injected even when the injector 11 is opened. The fuel injection time T is calculated as follows:
T=TP×FAF×K+TAUV
The ECU 0 inputs a signal j to the injector 11 for the fuel injection time T, and opens the valve of the injector 11 to inject fuel.

The air-fuel ratio feedback control converges the air-fuel ratio of the mixture filled in the cylinder 1, and therefore the air-fuel ratio of the exhaust gas discharged from the cylinder 1 and led to the catalyst 41, to a desired target air-fuel ratio, thereby maximizing the purification efficiency of harmful substances in the catalyst 41. The air-fuel ratio feedback correction coefficient FAF is determined based on the output signal f of the air-fuel ratio sensor 43 upstream of the catalyst 41. As shown in FIG. 2, the ECU 0 compares the output voltage f of the air-fuel ratio sensor 43, which detects the air-fuel ratio of the gas upstream of the catalyst 41, with a judgment voltage value corresponding to the target air-fuel ratio, and judges it to be lean if it is higher than the judgment voltage value, and rich if it is lower than the judgment voltage value. Then, the ECU 0 increases or decreases the feedback correction coefficient FAF based on the judgment result of the air-fuel ratio of the gas upstream of the catalyst 41.

Specifically, when the result of the determination of the air-fuel ratio of the gas upstream of the catalyst 41 reverses from lean to rich (after the delay time TDR described below has elapsed), the feedback correction coefficient FAF is decreased by the skip value RSM. In addition, while the air-fuel ratio is determined to be rich, the feedback correction coefficient FAF is gradually decreased by the lean integral value KIM per calculation cycle (control cycle). The period of the calculation cycle is equal to the period in which each cylinder 1 of the internal combustion engine reaches a new cycle (a series of intake stroke-compression stroke-expansion stroke-exhaust stroke). It is also possible to increase the absolute value of the lean integral value KIM as the absolute value of the difference or ratio between the determination voltage value and the output voltage value f of the air-fuel ratio sensor 43 increases.

On the other hand, when the result of the determination of the air-fuel ratio of the gas upstream of the catalyst 41 reverses from rich to lean (after the delay time TDL described below has elapsed), the feedback correction coefficient FAF is increased by the skip value RSP. In addition, while the air-fuel ratio is determined to be lean, the feedback correction coefficient FAF is gradually increased by the rich integral value KIP per calculation cycle. Note that it is also possible to increase the absolute value of the rich integral value KIP as the absolute value of the difference or ratio between the output voltage value f of the air-fuel ratio sensor 43 and the determination voltage value increases.

When the feedback correction coefficient FAF, which is multiplied by the basic injection amount TP, decreases, the amount of fuel injected by the injector 11 is reduced, and the air-fuel ratio of the mixture becomes leaner. When the feedback correction coefficient FAF increases, the amount of fuel injected by the injector 11 is increased, and the air-fuel ratio of the mixture becomes richer.

However, when the output voltage f of the air-fuel ratio sensor 43 fluctuates so as to cross the judgment voltage value, the judgment result of the air-fuel ratio of the gas upstream of the catalyst 41 is not immediately reversed, but rather the judgment result is reversed after the delay times TDL and TDR have elapsed. That is, when the output voltage f of the air-fuel ratio sensor 43 switches from rich to lean (below the judgment voltage value), it is determined that the air-fuel ratio has reversed from rich to lean after the lean judgment delay time TDL has elapsed. Also, when the output voltage f of the air-fuel ratio sensor 43 switches from lean to rich (above the judgment voltage value), it is determined that the air-fuel ratio has reversed from lean to rich after the rich judgment delay time TDR has elapsed.

The lean judgment delay time TDL and rich judgment delay time TDR are provided to prevent chattering, which occurs when noise is mixed into the output signal f of the air-fuel ratio sensor 43 and the lean/rich air-fuel ratio judgment result is inverted multiple times in a short period of time, causing the fuel injection amount to fluctuate and increase or decrease.

The delay times TDL and TDR increase and decrease depending on the correction amount FACF. FIG. 3 illustrates the relationship between the correction amount FACF and the delay times TDL and TDR. In FIG. 3, the lean judgment delay time TDL is shown by a dashed line, and the rich judgment delay time TDR is shown by a solid line. As the correction amount FACF increases, the lean judgment delay time TDL is shortened and the rich judgment delay time TDR is extended. This delays the time when the feedback correction coefficient FAF changes from an increase to a decrease, and accelerates the time when it changes from a decrease to an increase. As a result, the fuel injection amount increases on average, and the target air-fuel ratio of the gas flowing into the catalyst 41, which should be converged by air-fuel ratio feedback control, shifts to the rich side.

Conversely, the smaller the correction amount FACF, the longer the lean judgment delay time TDL and the shorter the rich judgment delay time TDR. This makes it faster for the feedback correction coefficient FAF to change from increasing to decreasing, and slows down the change from decreasing to increasing. As a result, the fuel injection amount decreases on average, and the target air-fuel ratio of the gas flowing into the catalyst 41 shifts to the lean side.

During air-fuel ratio feedback control, ECU0 also calculates the above-mentioned correction amount FACF. As shown in FIG. 4, when calculating the correction amount FACF, ECU0 compares the output voltage g of the air-fuel ratio sensor 44 that detects the air-fuel ratio of the gas downstream of the catalyst 41 with a judgment voltage value corresponding to the theoretical air-fuel ratio or a target air-fuel ratio in the vicinity thereof, and judges the air-fuel ratio to be rich if it is higher than the judgment voltage value, and lean if it is lower than the judgment voltage value. This judgment voltage value does not necessarily match the judgment voltage value compared with the output signal f of the air-fuel ratio sensor 43. Then, ECU0 increases or decreases the correction amount FACF based on the judgment result of the air-fuel ratio of the gas downstream of the catalyst 41.

Specifically, while the air-fuel ratio of the gas downstream of the catalyst 41 is judged to be rich, the correction amount FACF is gradually decreased by the lean integral value FACFKIM per calculation cycle, while while the air-fuel ratio is judged to be lean, the correction amount FACF is gradually increased by the rich integral value FACFKIP per calculation cycle. The absolute value of the lean integral value FACFKIM may be increased as the absolute value of the difference or ratio between the judgment voltage value and the output voltage value g of the air-fuel ratio sensor 44 increases, and the absolute value of the rich integral value FACFKIP may be increased as the absolute value of the difference or ratio between the output voltage g of the air-fuel ratio sensor 44 and the judgment voltage value increases. As already mentioned, when the correction amount FACF decreases, the target air-fuel ratio of the gas flowing into the catalyst 41 moves toward lean, and when the correction amount FACF increases, the target air-fuel ratio of the gas flowing into the catalyst 41 moves toward rich.

While the internal combustion engine is stopped, fuel vapor that has evaporated in the fuel tank 7 is collected in the canister 61 of the fuel vapor emission control device 6. After the internal combustion engine is started (particularly during a cold start), the VSV 65 is opened and the fuel vapor is released into the intake passage 3 of the internal combustion engine via the purge gas passage 63.

As shown in FIG. 5, after starting the stopped internal combustion engine (particularly, cold start) (step S1), ECU0 opens the VSV 65 at an appropriate time to purge the fuel vapor that has accumulated in the canister 61 while the internal combustion engine was stopped (step S2).

The opening degree of the VSV 65 in the purge process is determined according to the pressure difference between the atmospheric pressure and the intake pressure (in the surge tank 33 or intake manifold 34) and the target flow rate of the purge gas. The target flow rate of the purge gas is the amount of intake air flowing through the intake passage 3 toward the cylinder 1 multiplied by the gradual purge rate, which is the proportion of the purge gas in the intake air. The gradual purge rate is a value calculated internally by the ECU 0, and as shown in FIG. 6, it gradually increases during the period when the VSV 65 is open and the purge process is performed, and becomes 0 when the VSV 65 is closed and the purge process is not performed. Map data that specifies the relationship between the pressure difference obtained by subtracting the intake pressure from the atmospheric pressure, the target flow rate of the purge gas, and the opening degree of the VSV 65 is stored in advance in the memory of the ECU 0. When performing the purge process, ECU0 searches the map using the current differential pressure and target flow rate as keys, determines the opening degree of VSV65 that should be realized, and operates VSV65 to that opening degree.

When the VSV 65 is opened, purge gas containing fuel vapor flows into the intake passage 3. Depending on the concentration of the fuel vapor, there is a possibility that the air-fuel ratio of the mixture filled into the cylinder 1 may be disturbed. Therefore, in this embodiment, the ECU 0 estimates the concentration of fuel components in the purge gas flowing through the purge gas passage 63 when the VSV 65 is open (step S3).

The concentration of fuel contained in the purge gas can be estimated, for example, based on the correction coefficient FAF that corrects the fuel injection amount TP by air-fuel ratio feedback control. When fuel is injected at an injection amount TP proportional to the amount of air taken into cylinder 1, if the VSV 65 is opened and the air-fuel ratio of the gas flowing through the exhaust passage 4 becomes richer than the target air-fuel ratio, the fuel components in the purge gas that has flowed into the intake passage 3 are considered to be rich. The concentration can be estimated to be higher as the feedback correction coefficient FAF decreases. Conversely, if the air-fuel ratio of the gas flowing through the exhaust passage 4 becomes leaner than the target air-fuel ratio, the fuel components in the purge gas that has flowed into the intake passage 3 are considered to be lean. The concentration can be estimated to be lower as the feedback correction coefficient FAF increases.

Incidentally, the amount of fuel injected from the injector 11 can also be adjusted to increase or decrease depending on the concentration of the fuel components estimated in step S3. If the concentration of the fuel components in the purge gas is high, the correction coefficient K is decreased accordingly, and the fuel injection amount T is corrected to decrease. If the concentration of the fuel components in the purge gas is low, the correction coefficient K is increased accordingly, and the fuel injection amount T is corrected to increase.

In addition, ECU0 counts the cumulative amount (or time integral) of the flow rate of purge gas discharged into the intake passage 3 through the purge gas passage 63 after the internal combustion engine is started (step S4). The flow rate of purge gas per unit time can be estimated based on the opening degree of the VSV 65 at that time. The flow rate of purge gas increases as the opening degree of the VSV 65 increases. Needless to say, when the VSV 65 is closed, the flow rate of purge gas is zero.

Then, ECU0, when it is determined that the cumulative flow rate of the purge gas flowing through the purge gas passage 63 since the start of the internal combustion engine exceeds a predetermined amount (step S5) and that the estimated concentration of the fuel components in the purge gas exceeds a threshold value (step S6), opens the VSV 65 to a larger degree when performing the purging process of the canister 61 thereafter than when these conditions are not met (step S7), thereby further increasing the flow rate of the purge gas flowing through the purge gas passage 63.

The satisfaction of the condition in step S5 indicates that a certain amount of time has passed since the internal combustion engine was started, and the accuracy of the estimation of the concentration of the purge gas has improved. If the concentration of the purge gas exceeds the threshold value and is rich, it means that it is necessary to purge the fuel vapor in the canister 61 as quickly as possible, and therefore the opening of the VSV 65 is further increased in the subsequent purge process.

6 shows an example of the canister purge control by the ECU 0 of this embodiment. In FIG. 6, time _t0 is the start time of the internal combustion engine. Time _t1 to time _t2 and time _t3 to time _t7 correspond to periods during which the VSV 65 is opened to perform the purge process of the canister 61.

Time _t4 in Fig. 6 is the time when the concentration of fuel components in the purge gas estimated by the ECU 0 exceeds a threshold value. Time _t5 is the time when the cumulative flow rate of the purge gas since the start of the internal combustion engine counted by the ECU 0 is thought to exceed a predetermined amount. After both conditions of steps S5 and S6 are satisfied, the ECU 0 of this embodiment sets the increase amount per unit time of the gradually changing purge rate to be larger than before. As a result, the target flow rate of the purge gas increases, and the opening degree of the VSV 65 determined according to the target flow rate becomes larger. This is shown by the change in the opening degree of the VSV 65 after time _t6 .

In this embodiment, the fuel vapor emission suppression device 6 includes a connection passage 62 connected to the fuel tank 7, a canister 61 that captures fuel vapor generated in the fuel tank 7 and flows through the connection passage 62, an inlet passage 64 that is connected to the canister 61 and can introduce air, a purge gas flow passage 63 that connects the canister 61 to the intake passage 3 of the internal combustion engine and releases the fuel vapor captured in the canister 61 into the intake passage 3 connected to the cylinder 1 of the internal combustion engine, and a control valve 65 that opens and closes the purge gas flow passage 63. After starting the internal combustion engine, the control valve 65 is opened to a smaller degree than the maximum opening degree to release the purge gas into the intake passage 3, the concentration of the fuel components in the purge gas flowing through the purge gas flow passage 63 is estimated, and when the cumulative flow rate of the purge gas flowing through the purge gas flow passage 63 exceeds a predetermined amount and the concentration of the fuel components in the purge gas exceeds a threshold value, the control device 0 for the internal combustion engine is configured to operate the control valve 65 to a larger opening degree when opening the control valve 65 thereafter, compared to when this is not the case.

According to this embodiment, the opening of the control valve 65 is somewhat reduced immediately after the internal combustion engine is started, to prevent a large amount of purge gas from flowing into the intake passage 3 and significantly disrupting the air-fuel ratio of the mixture. After a certain amount of time has passed since the internal combustion engine was started, and the concentration of the fuel components in the purge gas can be accurately estimated, if the concentration of the purge gas is high, the opening of the control valve 65 is further increased (sometimes fully opened), and the flow rate of the purge gas is increased, causing the vapor of the fuel components captured in the canister 61 to be released early.

The fuel vapor released from the canister 61 into the intake passage 3 is burned in the cylinder 1. This allows the amount of fuel injection to be reduced accordingly, which is expected to improve practical fuel economy.

The present invention is not limited to the embodiment described above. The specific configuration of each part and the processing procedure can be modified in various ways without departing from the spirit of the present invention.

The present invention can be applied to the control of internal combustion engines installed in vehicles, etc.

0...Control unit (ECU)
REFERENCE SIGNS LIST 1 cylinder 11 injector 3 intake passage 32 throttle valve 4 exhaust passage 41 catalyst 6 evaporative emission control device 61 canister 62 connection passage 63 purge gas passage 64 introduction passage 65 control valve (purge VSV)
7...Fuel tank b...Crank angle signal c...Accelerator opening signal f, g...Air-fuel ratio signal h...Atmospheric pressure signal j...Fuel injection signal k...Throttle valve opening operation signal n...Control valve opening operation signal

Claims (1)

The control device controls an internal combustion engine equipped with a fuel evaporative emission control device, the control device comprising: a connection passage connected to a fuel tank; a canister for capturing fuel vapor generated in the fuel tank and flowing through the connection passage; an introduction passage connected to the canister and capable of introducing air; a purge gas flow passage that communicates the canister with an intake passage connected to a cylinder of the internal combustion engine and releases purge gas containing the fuel vapor captured in the canister into the intake passage; and a control valve for opening and closing the purge gas flow passage,
A control device for an internal combustion engine that, after starting an internal combustion engine, opens a control valve to an opening smaller than the maximum opening in order to release purge gas into an intake passage, estimates the concentration of fuel components in the purge gas flowing through a purge gas flow path, and, if the integrated flow rate of the purge gas that has flowed through the purge gas flow path exceeds a predetermined amount and the concentration of the fuel components in the purge gas exceeds a threshold value and is thus rich , increases the opening of the control valve when the control valve is subsequently opened, compared to cases where this is not the case.

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