JP2021042741A - Control device of internal combustion engine - Google Patents

Abstract

To provide a control device of an internal combustion engine capable of improving estimation accuracy of an adsorption quantity of evaporated fuel in a canister.SOLUTION: In an internal combustion engine including a state detection sensor for detecting a prescribed state quantity which varies in accordance with ventilation resistance of a canister, and an operation state sensor for detecting an operation state of the internal combustion engine, a control device of this invention calculates a reference state quantity which is a state quantity when an adsorption quantity of evaporated fuel in the canister is a prescribed quantity on the basis of the operation state of the internal combustion engine detected by the operation state sensor, calculates an estimated value of the adsorption quantity of the evaporated fuel in the canister on the basis of the comparison between the reference state quantity and the state quantity detected by the state detection sensor, and controls the internal combustion engine on the basis of the estimated value.SELECTED DRAWING: Figure 3

Description

The present invention relates to a control device for an internal combustion engine, and more particularly to a technique for estimating an adsorption amount of evaporated fuel in a canister.

The evaporative fuel processing apparatus disclosed in Patent Document 1 includes a canister that collects evaporative fuel generated in a fuel tank that stores fuel supplied to an internal combustion engine, and a purge that connects the canister and the intake system of the engine. A passage, a purge control valve provided in the purge passage and controlling the flow rate of the purge gas flowing through the purge passage, a purge gas flow control means for controlling the opening degree of the purge control valve, and an evaporative fuel concentration in the purge gas. It is provided with an estimated evaporative fuel concentration estimation means and a fuel amount correction means for correcting the amount of fuel supplied to the engine as the estimated evaporative fuel concentration increases.

Japanese Unexamined Patent Publication No. 2018-066351

By the way, the larger the amount of adsorbed fuel evaporated in the canister, in other words, the higher the concentration of adsorbed gas in the canister, the larger the ventilation resistance (pressure loss) of the canister. But the purge flow rate will be different.
Therefore, the ventilation resistance of the canister causes an error in the estimation of the evaporated fuel concentration, and the control of the internal combustion engine based on the estimated concentration value may deteriorate the operability and the exhaust property of the internal combustion engine.

The present invention has been made in view of the conventional circumstances, and an object of the present invention is to provide a control device for an internal combustion engine capable of improving the estimation accuracy of the adsorption amount of evaporated fuel in a canister.

According to the present invention, in one embodiment of the internal combustion engine, the internal combustion engine includes a state detection sensor that detects a predetermined state amount that changes depending on the ventilation resistance of the canister, and an operating state sensor that detects the operating state of the internal combustion engine. The reference state amount, which is the state amount when the adsorption amount of the evaporated fuel in the canister is a predetermined amount, is obtained based on the operating state of the internal combustion engine detected by the operating state sensor, and the reference state amount and the state are obtained. Based on the comparison with the state amount detected by the detection sensor, an estimated value of the adsorption amount of the evaporated fuel in the canister is obtained, and the internal combustion engine is controlled based on the estimated value.

According to the above invention, it is possible to improve the estimation accuracy of the adsorption amount of the evaporated fuel in the canister.

It is a system block diagram of an internal combustion engine. It is a time chart which shows the correlation between the adsorption amount CAA of the evaporated fuel in a canister, and the pressure PAR in the open pipe to the atmosphere of a canister. It is a flowchart which shows the procedure of the estimation process of the adsorption amount CAA. It is a diagram which shows the map for obtaining the basic value PARB of a pressure PAR. It is a diagram which shows the correlation of the pressure PAR, the purge flow rate, and the adsorption amount CAA. It is a diagram which shows the correlation of the 1st correction coefficient PC1 for correcting the difference ΔP, the engine rotation speed, and the intake air amount. It is a diagram which shows the correlation of the 2nd correction coefficient PC2 for correcting a difference ΔP, and the opening degree of a purge control valve. It is a diagram which shows the correlation of the difference ΔPA and the adsorption amount CAA. It is a flowchart which shows the procedure of the update process of the adsorption amount CAA. It is a time chart which shows the correlation between the intake pipe pressure and the update process of the suction amount CAA. It is a flowchart which shows the procedure of determining the clogging occurrence of a filter. It is a time chart which shows the difference of the pressure transition depending on the presence or absence of the clogging of the filter.

Hereinafter, embodiments of the internal combustion engine control device according to the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an aspect of an internal combustion engine including an evaporative fuel processing device.
The internal combustion engine 1 shown in FIG. 1 is a V-type internal combustion engine provided with a turbocharger 2 as a supercharger and an evaporative fuel processing device 3, and is mounted as a power source in a vehicle (not shown).

The intake pipe 4 of the internal combustion engine 1 is provided with the compressor 2a of the turbocharger 2, the intercooler 5, and the throttle valve 6 in this order from the upstream.
The turbocharger 2 is composed of a compressor 2a and a turbine 2b. By rotating the turbine 2b by the exhaust gas flowing through the exhaust pipe 21, the compressor 2a provided coaxially with the turbine 2b is rotated, and the compressor 2a is the intake pipe 4 The intake air flowing through the turbine is compressed (supercharged) and supplied to the internal combustion engine 1.

The intercooler 5 cools the supercharged air which is the intake air compressed (supercharged) by the compressor 2a.
The throttle valve 6 adjusts the amount of intake air sucked into the internal combustion engine 1 by adjusting the opening area of the intake pipe 4.

The evaporative fuel processing device 3 is a device that collects the evaporative fuel generated in the fuel tank 7 in the canister 8 and then purges the evaporative fuel from the canister 8 to the intake pipe 4 of the internal combustion engine 1.
The canister 8 is a device in which the case is filled with an adsorbent such as activated carbon capable of adsorbing and desorbing evaporative fuel.

The canister 8 and the fuel tank 7 are communicated with each other via the evaporative fuel pipe 9, and the evaporative fuel generated in the fuel tank 7 reaches the canister 8 through the evaporative fuel pipe 9 and is adsorbed by the adsorbent of the canister 8. ..
Further, the canister 8 is open to the atmosphere through the atmosphere opening pipe 10.
A filter 10a for filtering and introducing air is arranged at the atmospheric opening end of the atmospheric opening pipe 10, and an orifice 10b for adjusting the flow rate is provided in the atmospheric opening pipe 10 downstream of the filter 10a.

Further, the canister 8 is connected to the intake pipe 4 downstream of the throttle valve 6 via the first purge pipe 11.
The purge control valve 12 and the first check valve 13 are provided in the first purge pipe 11 in this order from the canister 8.

The purge control valve 12 is a solenoid valve whose opening degree is controlled by an electric signal output from the control device 14, and the flow rate of purge gas from the canister 8 is controlled according to the opening degree of the purge control valve 12.
The first check valve 13 is a mechanical valve that opens and closes according to the front-rear differential pressure, and the intake pipe pressure IP, which is the pressure in the intake pipe 4 downstream of the throttle valve 6, becomes a negative pressure and the suction force is applied to the valve body. Opens when the action is applied.

Further, a reflux pipe 15 for communicating the intake pipe 4 downstream of the compressor 2a and the intake pipe 4 upstream of the compressor 2a is provided.
A nozzle portion 15a is provided in the middle of the recirculation pipe 15, and the recirculation pipe 15 downstream of the nozzle portion 15a and the first purge pipe 11 between the purge control valve 12 and the first check valve 13 are second. It is communicated via the purge pipe 16.

The inner diameter of the nozzle portion 15a gradually narrows toward the upstream of the compressor 2a, and accelerates the supercharged air flowing from the intake pipe 4 downstream of the compressor 2a to the intake pipe 4 upstream of the compressor 2a.
Then, a negative pressure is generated in the second purge pipe 16 by the high-speed air flow injected from the nozzle portion 15a, and the air in the second purge pipe 16 is drawn into the supercharged air flow by the negative pressure to supercharge. The air and the air in the second purge pipe 16 are discharged to the intake pipe 4 upstream of the compressor 2a.

That is, the ejector 17 is configured by the nozzle portion 15a and the second purge pipe 16 communicating with the downstream of the nozzle portion 15a, and the evaporated fuel is purged from the canister 8 by the negative pressure generated by the ejector 17.
A second check valve 18 is provided in the middle of the second purge pipe 16.
Like the first check valve 13, the second check valve 18 is a mechanical valve that opens and closes according to the front-rear differential pressure. The pressure generated by the ejector 17 becomes a negative pressure, and a suction force is applied to the valve body. When it acts, it opens.

Then, the evaporated fuel adsorbed on the adsorbent of the canister 8 is desorbed from the adsorbent together with the air introduced into the canister 8 via the open air pipe 10 by the negative pressure of the intake pipe or the negative pressure generated by the ejector 17. Then, it is purged to the intake pipe 4 via the first purge pipe 11 or the second purge pipe 16.
That is, when the first check valve 13 is opened, the evaporated fuel adsorbed on the adsorbent of the canister 8 is purged into the intake pipe 4 downstream of the throttle valve 6 via the first purge pipe 11.
On the other hand, when the second check valve 18 is opened, the evaporated fuel adsorbed on the adsorbent of the canister 8 is purged into the intake pipe 4 upstream of the compressor 2a via the second purge pipe 16.

Here, the intake pipe pressure IP, which is the pressure in the intake pipe 4 downstream of the throttle valve 6, rises according to the increase in the load of the internal combustion engine 1 and switches from the negative pressure to the positive pressure. Further, the ejector 17 generates a larger negative pressure as the load (supercharging pressure) of the internal combustion engine 1 increases.
In the evaporated fuel treatment device 3, when the suction force acting on the first check valve 13 is larger than the suction force acting on the second check valve 18, in other words, the intake pipe pressure IP is the generated pressure of the ejector 17. When it is lower than, the first check valve 13 opens and the second check valve 18 closes.

On the other hand, when the suction force acting on the second check valve 18 is larger than the suction force acting on the first check valve 13, in other words, when the generated pressure of the ejector 17 is lower than the intake pipe pressure IP. The first check valve 13 closes and the second check valve 18 opens.
Therefore, in the evaporative fuel processing device 3, the evaporated fuel is purged through the first purge pipe 11 according to the increase in the load (intake pipe pressure IP) of the internal combustion engine 1 via the second purge pipe 16. It switches to the state where the evaporated fuel is purged.

The fuel injection device 19 is a device that injects fuel into the intake port of each cylinder of the internal combustion engine 1, and the fuel injection amount and fuel injection are performed according to the fuel injection pulse signal (air-fuel ratio control signal) output by the control device 14. Timing is controlled.
The internal combustion engine 1 may include, as a fuel injection device 19, a device that directly injects fuel into the combustion chamber of the internal combustion engine 1.

The control device 14 is an electronic control device mainly composed of a microcomputer equipped with a CPU, ROM, RAM, etc., performs calculations based on input information, and obtains the results of the calculations in the purge control valve 12 and the fuel injection device 19. Output to.
The control device 14 acquires signals output by various sensors (operating state sensors) that detect the operating conditions of the internal combustion engine 1, controls the opening degree of the purge control valve 12, and fuel injection by the fuel injection device 19. Outputs a signal that controls the amount.

As various sensors, an intake pipe pressure sensor 22 that detects the intake pipe pressure IP that is the pressure in the intake pipe 4 downstream of the throttle valve 6, and an air flow that detects the intake air amount QA of the internal combustion engine 1 in the intake pipe 4 upstream of the compressor 2a. The sensor 23, the intake air temperature sensor 24 that detects the intake temperature IAT of the internal combustion engine 1, and the exhaust pipe 21 between the turbine 2b and the catalyst converter 25 are arranged, and the air-fuel ratio AFR of the internal combustion engine 1 is based on the oxygen concentration in the exhaust. The internal combustion engine 1 is provided with an operating state sensor for detecting the operating state of the internal combustion engine 1, such as an air-fuel ratio sensor 26 for detecting the air-fuel ratio sensor 26 and a rotating speed sensor 29 for detecting the rotational speed NE of the internal combustion engine 1.
Further, a pressure sensor 27 for detecting the pressure PAR in the atmosphere opening pipe 10 is arranged between the orifice 10b and the canister 8.

Here, the control device 14 obtains an estimated value of the adsorption amount of the evaporated fuel in the canister 8, and based on the obtained estimated value, determines the opening degree of the purge control valve 12 and / or the fuel injection amount by the fuel injection device 19. Control to control the operation of the internal combustion engine 1.
Hereinafter, the process of estimating the adsorption amount by the control device 14 will be described.
The control device 14 opens the purge control valve 12 to purge the evaporated fuel from the canister 8, and the pressure PAR in the atmosphere opening pipe 10 detected by the pressure sensor 27 (in other words, upstream of the canister 8). Based on the comparison between the pressure in the pipe) and the basic value PARB of the pressure PAR, the adsorption amount CAA of the evaporated fuel in the canister 8 is estimated.

The pressure PAR detected by the pressure sensor 27 is the pressure of the inflow air of the canister 8, and is a state quantity that correlates with the flow rate of the air introduced into the canister 8, and changes depending on the ventilation resistance of the canister 8.
The pressure sensor 27 corresponds to a state detection sensor that detects a predetermined state amount that changes depending on the ventilation resistance of the canister 8.

In the present embodiment, the air flow rate introduced into the canister 8 is replaced with the pressure for measurement, but instead of the pressure sensor 27, the flow meter 28 is arranged in the atmospheric opening pipe 10 between the orifice 10b and the canister 8. Can be done.
Further, the basic value PARB is a value obtained in advance as a pressure PAR when the adsorption amount CAA of the evaporated fuel in the canister 8 is a predetermined amount (for example, the minimum amount or the maximum amount) and stored in the memory of the control device 14. It corresponds to the reference state quantity.

FIG. 2 is a time chart showing how the adsorption amount CAA and the pressure PAR of the evaporated fuel in the canister 8 change after the start of purging the evaporated fuel.
Note that FIG. 2 shows changes in the suction amount CAA and the pressure PAR when the operating state (engine rotation speed and engine load) of the internal combustion engine 1 is constant and the purge control valve 12 is opened to a constant opening degree. ..

When the purge control valve 12 is switched from the closed state to the open state and the purge is started, if the adsorption amount CAA of the evaporated fuel in the canister 8 is large, the pressure sensor 27 detects it because the ventilation resistance of the canister 8 is large. The pressure PAR to be applied becomes a value close to the atmospheric pressure.
After that, as the suction amount CAA gradually decreases due to the continuation of purging, the ventilation resistance of the canister 8 decreases, and the pressure PAR detected by the pressure sensor 27 gradually decreases.

Then, when the adsorption amount CAA of the evaporated fuel in the canister 8 reaches the minimum amount (in other words, an empty state), the pressure PAR detected by the pressure sensor 27 corresponds to the ventilation resistance when the adsorption amount CAA is the minimum amount. Will be held at the value.
That is, the difference ΔP between the pressure PAR actually detected by the pressure sensor 27 and the pressure PAR when the adsorption amount CAA is the minimum amount correlates with the adsorption amount CAA of the evaporated fuel in the canister 8, and the larger the difference ΔP, the more. , The amount of adsorbed fuel adsorbed by the canister 8 CAA is large.

Therefore, the control device 14 stores the pressure PAR when the suction amount CAA is the minimum amount in the memory as the basic value PARB, and obtains the difference ΔP between the basic value PARB on the memory and the pressure PAR detected by the pressure sensor 27. , The adsorption amount CAA is estimated based on the difference ΔP.
The basic value PARB is not limited to the pressure PAR when the adsorption amount CAA of the vaporized fuel in the canister 8 is the minimum amount, and for example, the adsorption amount CAA of the vaporized fuel in the canister 8 is the maximum amount (saturation amount). The pressure can be PAR.

When the basic value PARB is the pressure PAR when the adsorption amount CAA of the evaporated fuel in the canister 8 is the maximum amount, the larger the difference ΔP between the pressure PAR detected by the pressure sensor 27 and the basic value PARB, the more evaporation in the canister 8. The amount of fuel adsorbed CAA is small.
Further, the basic value PARB can be set to the pressure PAR when the adsorption amount CAA of the evaporated fuel in the canister 8 is a predetermined ratio (for example, 10%) of the maximum amount.

FIG. 3 is a flowchart showing a procedure of the adsorption amount CAA estimation process performed by the control device 14.
The control device 14 executes the routine shown in FIG. 3 by interrupt processing at predetermined time intervals.

In step S1001, the control device 14 obtains the basic value PARB based on the operating state of the internal combustion engine 1 detected by the operating state sensors such as the airflow sensor 23 and the rotation speed sensor 29.
Here, the basic value PARB is a pressure PAR when the adsorption amount CAA of the evaporated fuel in the canister 8 is the minimum amount and the opening degree of the purge control valve 12 is a predetermined opening degree, and is an internal combustion engine by an experiment or a simulation. It is a value obtained in advance for each operating condition of 1.

FIG. 4 shows a map that stores the basic value PARB according to the operating conditions of the internal combustion engine 1.
The control device 14 is a map in which the data of the basic value PARB is input in advance for each lattice divided into a plurality of data by the combination of the data of the rotation speed NE of the internal combustion engine 1 and the data of the intake air amount QA representing the engine load. It has a basic value map.

Since the pressure PAR when the adsorption amount CAA of the evaporated fuel in the canister 8 is the minimum amount changes according to the engine speed NE and the engine load, the basic value map is based on the engine speed NE and the engine load. Store the basic value PARB.
Here, the basic value PARB is set to a higher value when the engine rotation speed NE is low and the intake air amount QA is large.

Then, in step S1001, the control device 14 searches the basic value map for the basic value PARB stored corresponding to the current engine rotation speed NE and the intake air amount QA.
The control device 14 can calculate the basic value PARB based on a function having the engine rotation speed NE and the intake air amount QA (engine load) as variables.

FIG. 5 shows the correlation between the purge flow rate, the pressure PAR, and the adsorption amount CAA.
FIG. 5 shows that the purge flow rate decreases as the adsorption amount CAA increases, and increases as the adsorption amount CAA decreases, and the pressure PAR increases as the purge flow rate decreases.

Therefore, the control device 14 sets the pressure PAR at the purge flow rate when the adsorption amount CAA of the evaporated fuel in the canister 8 is a predetermined amount as the basic value PARB, and as shown in FIG. 4, according to the operating conditions of the internal combustion engine 1. To obtain the basic value PARB.
The control device 14 uses the intake air amount QA data as the engine operating condition used for calculating the basic value PARB, but the intake pipe pressure IP data can be used instead of the intake air amount QA data.

The control device 14 acquires the information on the opening degree of the purge control valve 12 in step S1002, and acquires the information on the atmospheric pressure in step S1003.
The control device 14 can acquire the output of the pressure sensor 27 in the closed state of the purge control valve 12 as a value equivalent to atmospheric pressure.

In step S1004, the control device 14 obtains the pressure PAR in the atmospheric release pipe 10 based on the output of the pressure sensor 27.
Further, in the next step S1005, the control device 14 normalizes the pressure PAR data obtained in step S1004 to the pressure based on the atmospheric pressure obtained in step S1003.

Then, in step S1006, the control device 14 obtains the difference ΔP (ΔP = | PARB-PAR |) between the basic value PARB obtained in step S1001 and the pressure PAR normalized in step S1005.
Next, in step S1007, the control device 14 obtains a first correction coefficient PC1 which is a correction value for correcting the difference ΔP according to the operating state of the internal combustion engine 1.

FIG. 6 shows a map that stores the first correction coefficient PC1 according to the engine rotation speed NE and the intake air amount QA.
In the map of FIG. 6, the first correction coefficient PC1 is set to a higher value when the engine rotation speed NE is low and the intake air amount QA is large, and the difference ΔP is set to a low engine rotation speed NE due to the first correction coefficient PC1. When the intake air amount QA is large, the engine speed NE is corrected to a larger value than when the intake air amount QA is small.
By correcting the difference ΔP by the first correction coefficient PC1, the adsorption amount CAA can be accurately estimated from the difference ΔP even if the operating state (engine rotation speed and engine load) of the internal combustion engine 1 is different.

In the next step S1008, the control device 14 obtains a second correction coefficient PC2 which is a correction value for correcting the difference ΔP according to the opening degree of the purge control valve 12.
FIG. 7 shows the correlation between the opening degree of the purge control valve 12 and the second correction coefficient PC2.

For example, when the opening degree of the purge control valve 12 is fully open (maximum control opening), the control device 14 sets the second correction coefficient PC2 to 1.0, and the opening degree of the purge control valve 12 is fully opened (100). %), The second correction coefficient PC2 is gradually changed to a higher value.
That is, since the difference ΔP with respect to the suction amount CAA changes depending on the opening degree of the purge control valve 12, the difference ΔP is corrected by the second correction coefficient PC2, and even if the opening degree of the purge control valve 12 is different, the difference ΔP is used. The adsorption amount CAA can be estimated accurately.

Then, the control device 14 proceeds to step S1009, and the difference ΔP obtained in step S1006 is set to the opening degree of the first correction coefficient PC1 obtained in step S1007 based on the engine operating conditions and the purge control valve 12 in step S1008. It is corrected by the second correction coefficient PC2 obtained based on the above, and the correction result is set to the difference ΔPA (ΔPA = ΔP × PC1 × PC2) for finally obtaining the adsorption amount CAA.
Next, in step S1010, the control device 14 calculates the adsorption amount CAA from the corrected difference ΔPA. In other words, the control device 14 converts the data of the difference ΔPA into the data of the adsorption amount CAA in step S1010.

FIG. 8 is a diagram showing the correlation between the difference ΔPA and the adsorption amount CAA, that is, the conversion characteristics of the table for converting the data of the difference ΔPA into the adsorption amount CAA.
Since the control device 14 uses the pressure PAR when the adsorption amount CAA of the evaporated fuel in the canister 8 is the minimum amount as the basic value PARB, the larger the difference ΔPA, the larger the adsorption amount CAA is calculated.

By estimating the adsorption amount CAA according to the flowchart of FIG. 3, the control device 14 can suppress the occurrence of an estimation error of the adsorption amount CAA due to the ventilation resistance of the canister 8 and can estimate the adsorption amount CAA with high accuracy.
Then, the control device 14 improves the operability and exhaust properties of the internal combustion engine 1 by controlling the opening degree of the purge control valve 12 and / or the fuel injection amount by the fuel injection device 19 based on the estimated adsorption amount CAA. it can.

By the way, in the estimation process of the adsorption amount CAA according to the difference ΔPA, when the intake pipe pressure IP (or the pressure generated by the ejector 17) is high and the force for sucking the purge air into the intake pipe 4 becomes weak, the purge flow rate decreases and the difference ΔP also becomes small. Therefore, the estimation accuracy of the adsorption amount CAA is lowered.
In order to suppress the influence of such a decrease in estimation accuracy, the control device 14 limits the update process of the adsorption amount CAA used for controlling the opening degree of the purge control valve 12 and / or the fuel injection amount by the fuel injection device 19.

FIG. 9 is a flowchart showing a procedure for updating the adsorption amount CAA.
The control device 14 executes the routine shown in FIG. 9 by interrupt processing at predetermined time intervals.
First, in step S1201, the control device 14 estimates the adsorption amount CAA (evaporated fuel concentration in the canister 8) according to the procedure shown in the flowchart of FIG.

Next, the control device 14 proceeds to step S1202 and determines whether or not the deviation between the previous value and the latest value (current value) of the estimation result of the adsorption amount CAA is equal to or less than a predetermined value.
In other words, in step S1202, the control device 14 determines whether or not the amount of change in the estimation result of the adsorption amount CAA per predetermined time is equal to or less than the predetermined value.

If the deviation between the previous value and the latest value of the estimation result of the adsorption amount CAA exceeds a predetermined value, there is a possibility that an estimation error has occurred in the latest value, so the control device 14 is used for controlling the internal combustion engine 1. By terminating this routine as it is without updating the adsorption amount CAA, the update of the adsorption amount CAA used for controlling the internal combustion engine 1 is stopped and held at the previous value.
That is, the predetermined value to be compared with the change amount of the estimation result of the adsorption amount CAA per predetermined time is a value that does not exceed in the decrease change of the adsorption amount CAA in the normal purge state.

On the other hand, when the deviation between the previous value and the latest value of the estimation result of the adsorption amount CAA is not more than a predetermined value, the control device 14 proceeds to step S1203, and whether or not the intake pipe pressure IP is not more than the first predetermined value IP1. To judge.
The first predetermined value IP1 is for determining whether or not the estimation accuracy of the adsorption amount CAA is such that the latest estimation result cannot be reflected in the adsorption amount CAA used for controlling the internal combustion engine 1. Is the threshold of.

When the intake pipe pressure IP is higher than the first predetermined value IP1, the force for sucking purge air into the intake pipe 4 is weak, and the estimation accuracy of the adsorption amount CAA based on the difference ΔPA may be significantly lowered.
Therefore, the control device 14 stops updating the adsorption amount CAA used for controlling the internal combustion engine 1 by terminating this routine as it is without updating the adsorption amount CAA used for controlling the internal combustion engine 1.

On the other hand, when the intake pipe pressure IP is equal to or less than the first predetermined value IP1, the control device 14 proceeds to step S1204 and determines whether or not the intake pipe pressure IP is equal to or less than the second predetermined value IP2.
Here, the second predetermined value IP2 is a pressure lower than the first predetermined value IP1, and when the intake pipe pressure IP is equal to or less than the second predetermined value IP2, the control device 14 estimates the adsorption amount CAA based on the difference ΔPA. It shows that the pressure condition can be performed with sufficient accuracy.

Therefore, when the intake pipe pressure IP is equal to or less than the second predetermined value IP2, the control device 14 proceeds to step S1205, and normally updates the adsorption amount CAA used for controlling the internal combustion engine 1 based on the result estimated in step S1201 this time. To do.
On the other hand, when the intake pipe pressure IP is higher than the second predetermined value IP2, that is, when the intake pipe pressure IP is equal to or less than the first predetermined value IP1 and the intake pipe pressure IP is higher than the second predetermined value IP2, the control device 14 Goes to step S1206.

The state where the intake pipe pressure IP is equal to or less than the first predetermined value IP1 and the intake pipe pressure IP is higher than the second predetermined value IP2 is a condition in which the estimation result of the adsorption amount CAA can be obtained with sufficient accuracy, but it is used for control. It is a condition that is expected to obtain an estimation accuracy that can be reflected to some extent.
Therefore, in step S1206, the control device 14 performs a process of updating the adsorption amount CAA used for controlling the internal combustion engine 1 based on the result estimated in step S1201 of this time, but the estimated value associated with the update is compared with step S1205. The amount of change (update amount) of is limited to a small amount.

That is, the control device 14 limits the updated value to be closer to the previous value in step S1206 than in the case of updating in step S1205.
As a result, it is suppressed that the adsorption amount CAA used for controlling the internal combustion engine 1 is normally updated based on the estimation result having an error when the intake pipe pressure IP exceeds a predetermined pressure, and the internal combustion engine 1 is prevented from being normally updated due to the estimation error. It is possible to prevent deterioration of the drivability and exhaust properties of the engine.

The control device 14 can perform the update process in step S1206 by using a low-pass filter process, a weighted average calculation, or the like.
Further, the control device 14 can select either stop of update or normal update without limiting the update amount, and further, a plurality of limits of the update amount are set according to the intake pipe pressure IP. You can switch to stages.

FIG. 10 is a time chart showing the correlation between the adsorption amount CAA and the intake pipe pressure IP when the update process shown in the flowchart of FIG. 9 is performed.
Although the intake pipe pressure IP changes upward from time t0 to time t1 in FIG. 10, it is equal to or less than the second predetermined value IP2. Therefore, the control device 14 is used for controlling the internal combustion engine 1 based on the latest estimation result. The adsorption amount CAA is updated normally.

On the other hand, between the time t1 and the time t2, the intake pipe pressure IP becomes higher than the second predetermined value IP2 and equal to or less than the first predetermined value IP1, and the control device 14 of the internal combustion engine 1 is based on the latest estimation result. The suction amount CAA used for control is updated, but the amount of change (update amount) of the estimated value due to the update is limited smaller than when the intake pipe pressure IP is the second predetermined value IP2 or less.
Further, when the intake pipe pressure IP increases and the intake pipe pressure IP exceeds the first predetermined value IP1 between the time t2 and the time t3, the control device 14 stops updating the adsorption amount CAA used for controlling the internal combustion engine 1. Then, the suction amount CAA used for controlling the internal combustion engine 1 is maintained at the previous value.

By the way, the control device 14 is based on the data of the difference ΔPA calculated for estimating the adsorption amount CAA, and the presence or absence of clogging of the atmospheric opening pipe 10 (clogging of the filter 10a, etc.), which is an abnormality in the atmospheric introduction path of the canister 8. Can be determined.
FIG. 11 is a flowchart showing a procedure for determining clogging of the atmosphere opening pipe 10 by the control device 14.
The control device 14 executes the routine shown in FIG. 11 by interrupt processing at predetermined time intervals.

In step S1401, the control device 14 acquires the data of the difference ΔPA obtained according to the procedure shown in the flowchart of FIG.
Next, in step S1402, the control device 14 determines whether or not the difference ΔPA is equal to or greater than the predetermined value ΔPA1.

Here, when the difference ΔPA is a predetermined value ΔPA1 or more, the flow rate of the air introduced into the canister 8 is small, the adsorption amount CAA of the evaporated fuel in the canister 8 is large, or the atmosphere open pipe 10 is used. It is assumed that clogging (clogging of the filter 10a) has occurred.
When the difference ΔPA is equal to or greater than the predetermined value ΔPA1, the control device 14 proceeds to step S1403, and when the difference ΔPA is less than the predetermined value ΔPA1, the control device 14 terminates this routine as it is and determines that the air opening pipe 10 is clogged. do not do.

In step S1403, the control device 14 determines whether or not the intake pipe pressure IP is equal to or lower than the predetermined pressure THP.
The state where the intake pipe pressure IP is equal to or lower than the predetermined pressure THP indicates that the force for sucking the purge air into the intake pipe 4 is sufficiently high and the purging of the evaporated fuel from the canister 8 proceeds.

The control device 14 proceeds to step S1404 when the intake pipe pressure IP is equal to or lower than the predetermined pressure THP and the condition for the purging to proceed is satisfied.
On the other hand, when the intake pipe pressure IP is higher than the predetermined pressure THP and the purging does not proceed, the control device 14 terminates this routine as it is and does not determine the occurrence of clogging of the atmospheric opening pipe 10.

In step S1404, the control device 14 determines whether or not the opening POD of the purge control valve 12 is equal to or greater than the predetermined opening THO.
The state in which the opening POD of the purge control valve 12 is equal to or greater than the predetermined opening THO indicates that the purging flow rate is large and the purging of the evaporated fuel from the canister 8 is proceeding.

The control device 14 proceeds to step S1405 when the opening POD of the purge control valve 12 is equal to or larger than the predetermined opening THO and the condition for the purging to proceed is satisfied.
On the other hand, when the opening POD of the purge control valve 12 is smaller than the predetermined opening THO and the purging does not proceed, the control device 14 terminates this routine as it is and does not determine the occurrence of clogging of the atmospheric opening pipe 10.

In step S1405, the control device 14 opens the purge control valve 12 after switching the purge control valve 12 from the closed state to the open state, that is, the elapsed time T from starting the purging of the evaporated fuel from the canister 8. It is determined whether or not the time held in the is equal to or longer than the predetermined time THT.
When the elapsed time T is THT or more for a predetermined time, the canister 8 evaporates under the condition that the intake pipe pressure IP is the predetermined pressure THP or less and the opening POD of the purge control valve 12 is the predetermined opening THO or more. The fuel adsorption amount CAA is less than the predetermined amount, in other words, the difference ΔPA is estimated to be less than the predetermined value ΔPA1.

Here, the control device 14 determines in step S1402 that the difference ΔPA is equal to or greater than the predetermined value ΔPA1, and then proceeds to step S1405 through steps S1403 and S1404.
Therefore, when the control device 14 determines in step S1405 that the elapsed time T is equal to or greater than the predetermined time THT, the difference ΔPA is less than the predetermined value ΔPA1 (in other words, the adsorption amount CAA is less than the predetermined amount). Even though the presumed condition is satisfied, the difference ΔPA is actually maintained in a state of a predetermined value ΔPA1 or more (in other words, a state in which the adsorption amount CAA is a predetermined amount or more).

That is, in the state where the elapsed time T is determined to be equal to or longer than the predetermined time THT in step S1405, the purging progress is slower than the normal state (in other words, the decrease change of the adsorption amount CAA is slower than the reference). Abnormal state).
Then, the abnormality of the purging process occurs when the air flow rate introduced into the canister 8 becomes smaller than that in the normal state due to the clogging of the air opening pipe 10 (clogging of the filter 10a).

Therefore, when the control device 14 determines in step S1405 that the elapsed time T is equal to or longer than the predetermined time THT, the control device 14 proceeds to step S1406, determines the occurrence of clogging of the atmospheric opening pipe 10, and performs an abnormal time process based on the determination result. To do.
Here, the control device 14 performs a process of storing the result of the clogging determination as a diagnosis history in a memory as an abnormal time process when the occurrence of the clogging of the air release pipe 10 is determined, and an abnormality occurs in the driver of the vehicle (open to the atmosphere). A process for warning the occurrence of clogging of the pipe 10 and an abnormality in the evaporated fuel treatment device 3), a process for correcting the opening degree of the purge control valve 12, and the like are performed.

On the other hand, if the control device 14 determines in step S1405 that the elapsed time T is less than the predetermined time THT, the control device 14 terminates this routine as it is, and does not determine the occurrence of clogging of the atmosphere opening pipe 10.
In this way, the control device 14 determines whether or not the air opening tube 10 is clogged based on the data of the difference ΔPA calculated for estimating the adsorption amount CAA. Then, the control device 14 can promote the elimination of the abnormal state or suppress the influence of the occurrence of the abnormal state by performing the abnormal state processing when it is determined that the air opening pipe 10 is clogged.

FIG. 12 is a time chart showing a change in the pressure PAR in the atmosphere opening pipe 10 when the atmosphere opening pipe 10 is clogged (the filter 10a is clogged).
In FIG. 12, the change in the pressure PAR shown by the dotted line shows the characteristic in the normal state where the filter 10a is not clogged, and the change in the pressure PAR shown by the solid line is an abnormality in which the filter 10a is clogged. Shows the characteristics of time.
The change in the pressure PAR shown in FIG. 12 is a characteristic under the condition that the intake pipe pressure IP is the predetermined pressure THP or less and the opening POD of the purge control valve 12 is the predetermined opening THO or more.

Here, in the normal state where the filter 10a is not clogged, the difference ΔPA is less than the predetermined value ΔPA1 when the elapsed time T reaches the predetermined time THT (time t1).
On the other hand, when the filter 10a is clogged and abnormal, the flow rate of the air introduced into the canister 8 is reduced, so that the pressure PAR is maintained at a high value and the elapsed time T reaches the predetermined time THT ( Even at time t1), the difference ΔPA becomes equal to or greater than the predetermined value ΔPA1.
Therefore, the control device 14 can determine whether or not the filter 10a is clogged based on whether or not the difference ΔPA is maintained at the predetermined value ΔPA1 or more when the elapsed time T is the predetermined time THT or more.

The technical ideas described in the above embodiments can be used in combination as appropriate as long as there is no contradiction.
In addition, although the contents of the present invention have been specifically described with reference to preferred embodiments, it is obvious that those skilled in the art can adopt various modifications based on the basic technical idea and teaching of the present invention. Is.

For example, even when the internal combustion engine 1 is a naturally aspirated engine without a supercharger, it is clear that the adsorption amount CAA can be estimated as described above.
Further, the control device 14 can correct the data of the difference ΔP according to the fuel temperature, the remaining amount of fuel in the fuel tank 7, and the like.

1 ... Internal engine, 3 ... Evaporated fuel processing device, 4 ... Intake pipe, 6 ... Throttle valve, 7 ... Fuel tank, 8 ... Canister, 10 ... Open air pipe, 10a ... Filter, 10b ... orifice, 11 ... First purge Piping, 12 ... Purge control valve, 14 ... Control device, 16 ... Second purge piping, 17 ... Ejector, 19 ... Fuel injection device, 23 ... Airflow sensor (operating state sensor), 27 ... Pressure sensor (state detection sensor), 29 ... Rotation speed sensor (operating state sensor)

Claims (6)

A canister that adsorbs the evaporated fuel generated in the fuel tank,
A purge pipe that connects the canister and the intake pipe of the internal combustion engine and introduces purge gas from the canister into the intake pipe.
A purge control valve provided in the purge pipe and controlling the flow rate of purge gas from the canister,
A state detection sensor that detects a predetermined amount of state that changes depending on the ventilation resistance of the canister, and
An operating state sensor that detects the operating state of the internal combustion engine, and
It is a control device applied to an internal combustion engine equipped with
The reference state amount, which is the state amount when the adsorption amount of the evaporated fuel in the canister is a predetermined amount, is obtained based on the operating state of the internal combustion engine detected by the operating state sensor.
Based on the comparison between the reference state amount and the state amount detected by the state detection sensor, an estimated value of the adsorption amount of the evaporated fuel in the canister was obtained.
Control the internal combustion engine based on the estimated value.
Internal combustion engine control device. The predetermined state quantity detected by the state detection sensor is the pressure or flow rate of the inflow air to the canister.
The control device for an internal combustion engine according to claim 1. When the pressure of the intake pipe to which the purge pipe is connected exceeds a predetermined pressure, the update amount of the estimated value is limited to a small amount.
The control device for an internal combustion engine according to claim 1 or 2. The predetermined amount is the minimum or maximum amount of adsorption of evaporated fuel in the canister.
The control device for an internal combustion engine according to any one of claims 1 to 3. The difference between the reference state quantity and the state quantity detected by the state detection sensor is obtained.
The difference is corrected based on the operating state of the internal combustion engine and the opening degree of the purge control valve.
The estimated value is obtained based on the corrected difference.
The control device for an internal combustion engine according to any one of claims 1 to 4. When the decrease change of the estimated value is slower than the reference, the occurrence of an abnormality in the atmosphere introduction path of the canister is determined.
The control device for an internal combustion engine according to any one of claims 1 to 5.

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