JP2020180578A - Control device of evaporation fuel treatment device - Google Patents

Abstract

To provide a control device of an evaporation fuel treatment device which can control a purge control valve corresponding to a fuel adsorption amount of a canister during the execution of a purge.SOLUTION: This control device acquires information related to a fuel adsorption amount (ventilation resistance) of a canister by comparing a signal related to the pressure of an intake passage of an internal combustion engine in a valve-opening state of a purge control valve, or a signal related to atmospheric pressure, and a signal related to the pressure of an atmospheric air introduction passage of the canister, corrects a concentration estimation value of evaporation fuel based on an air-fuel ratio correction value on the basis of the fuel adsorption amount of the canister, and controls an opening of the purge control valve on the basis of the corrected concentration estimation value.SELECTED DRAWING: Figure 3

Description

The present invention relates to a control device for an evaporative fuel processing device that adsorbs evaporative fuel in a fuel tank to a canister.

Patent Document 1 has a canister in which the fuel evaporated in the fuel tank is introduced, and in an evaporative fuel processing mechanism that purges the evaporative fuel adsorbed in the canister into the intake passage of the internal combustion engine, the canister from the start of the vehicle. The ventilation resistance of the canister is detected based on the pressure change when the pressure in the fuel tank is changed by the pump until the evaporated fuel adsorbed on the fuel is purged into the intake passage, and based on the detected ventilation resistance. It is disclosed to estimate the fuel adsorption amount of the canister.

Japanese Unexamined Patent Publication No. 2005-139955

By the way, utilizing the unique relationship between the ventilation resistance of the canister and the amount of fuel adsorbed in the canister, the ventilation resistance of the canister is detected based on the pressure change when the pressure in the fuel tank is changed by the pump. When estimating the fuel adsorption amount of the canister based on the detected ventilation resistance, it is difficult to obtain the ventilation resistance (fuel adsorption amount) that changes depending on the execution of purging.

Here, when the fuel concentration of the purge gas is estimated and the opening degree of the purge control valve is controlled by using the air-fuel ratio feedback control during the purge, the suction negative pressure is reduced and the amount of fuel purged from the canister (purge). When the amount of fuel) decreases, the opening of the purge control valve increases.
When the suction negative pressure suddenly increases from the state where the opening of the purge control valve is large, the purge fuel amount suddenly increases and the air-fuel ratio is enriched, and the larger the ventilation resistance (fuel adsorption amount) of the canister, the more. There is a problem that the decrease in the amount of purge fuel becomes large as the suction negative pressure decreases, and the air-fuel ratio fluctuation becomes large when the suction negative pressure increases relatively.

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 evaporative fuel treatment device capable of controlling a purge control valve according to a fuel adsorption amount of a canister during execution of a purge. There is.

Therefore, the control device of the evaporative fuel treatment device according to the present invention has, as one aspect, a signal regarding the pressure or atmospheric pressure of the intake passage of the internal combustion engine and the atmosphere introduction passage of the canister with the purge control valve open. Based on the signal related to the pressure of, the information on the fuel adsorption amount in the canister is obtained, and the command signal of the opening degree of the purge control valve is obtained based on the information on the fuel adsorption amount.

According to the above invention, the purge control valve can be controlled according to the fuel adsorption amount of the canister during the purge execution, and the air-fuel ratio fluctuation of the internal combustion engine due to the purge can be suppressed.

It is a system block diagram which shows one aspect of the internal combustion engine which includes the evaporative fuel processing apparatus. It is a block diagram of the leak diagnosis module of the evaporative fuel processing apparatus. It is a functional block diagram of the control device of the evaporative fuel processing device. It is a flowchart which shows the procedure of the correction processing of the fuel injection amount by a control device. It is a flowchart which shows the procedure of opening degree control of a purge control valve by a control device. It is a diagram which shows the correlation between the differential pressure between the intake pipe pressure and the atmospheric opening pressure of a canister, and the amount of evaporated fuel adsorbed by a canister. It is a diagram which shows the correlation between the differential pressure between the atmospheric pressure and the atmospheric opening pressure of a canister, and the adsorption amount of evaporative fuel of a canister. It is a time chart which shows the change of the engine load, the air-fuel ratio, etc. when the purge control based on the comparison between the intake pipe pressure or the atmospheric pressure and the pressure of the atmosphere introduction passage of the canister is not performed. It is a time chart which shows the change of the engine load, the air-fuel ratio, etc. when the purge control based on the comparison between the intake pipe pressure or the atmospheric pressure and the pressure of the atmosphere introduction passage of the canister is performed.

Embodiments of the present invention will be described below.
FIG. 1 is a configuration diagram showing an aspect of an internal combustion engine 10 and an evaporative fuel processing device 50 mounted on a vehicle.
The internal combustion engine 10 has a cylinder block 11, a cylinder head 12, a piston 13, and a piston rod 14 that slidably supports the piston 13 in the cylinder block 11, and has a crown surface of the cylinder head 12 and the piston 13. A combustion chamber 15 is formed between the and.

The cylinder head 12 has an intake port 16 and an exhaust port 17.
One end of the intake port 16 opens into the combustion chamber 15, and the opening is opened and closed by an intake valve 19 that reciprocates in response to the rotation of the intake camshaft 18.
One end of the exhaust port 17 opens into the combustion chamber 15, and the opening is opened and closed by an exhaust valve 21 that reciprocates in response to the rotation of the exhaust camshaft 20.

The other end of the intake port 16 communicates with the intake collector 22, and one end of the intake duct 23 communicates with the intake collector 22. The other end of the intake duct 23 is open to the atmosphere.
The air cleaner 24, the compressor 25 of the supercharger, and the throttle valve 26 are arranged in this order from the upstream side in the intake duct 23.

The cylinder head 12 is provided with a fuel injection valve 27 (fuel injection device) for each cylinder, and the fuel injection valve 27 injects fuel directly into the combustion chamber 15.
The fuel injected into the combustion chamber 15 is ignited and burned by a spark plug (not shown), the piston 13 is pressed by this combustion pressure, the piston 13 reciprocates, and the crankshaft (not shown) rotates by the crank mechanism. To do.

The fuel tank 30 stores the fuel of the internal combustion engine 10, and the fuel pump 31 provided in the fuel tank 30 pumps the fuel in the fuel tank 30 to the fuel injection valve 27.
The internal combustion engine 10 has an evaporated fuel processing device 50 for suppressing leakage of evaporated fuel (evaporator) generated in the fuel tank 30.

The evaporative fuel processing device 50 includes a canister 51 that adsorbs evaporative fuel, an evaporative fuel passage 52 that connects the canister 51 and the fuel tank 30, an air introduction passage 53 that introduces air into the canister 51, a canister 51, and an internal combustion engine. It has a purge passage 54 that communicates with the intake passages (intake collector 22 and intake duct 23) of 10 and a purge control valve 55 provided in the purge passage 54.
The canister 51 is filled with activated carbon, and when the evaporated fuel generated in the fuel tank 30 flows in through the evaporated fuel passage 52, the evaporated fuel is adsorbed on the activated carbon inside.

When the purge passage 54 becomes negative pressure, the outside air (atmosphere) is sucked into the canister 51 from the atmosphere introduction passage 53, passes through the inside of the canister 51, and flows into the purge passage 54.
At this time, the evaporated fuel adsorbed on the activated carbon of the canister 51 is desorbed, and the desorbed evaporated fuel is guided to the purge passage 54 together with the outside air and merges with the intake air in the intake passage (intake collector 22 and intake duct 23). It flows into the combustion chamber 15 and is burned in the combustion chamber 15.

At the atmosphere opening 53a of the air introduction passage 53, a filter 53b for filtering the air sucked by the canister 51 is provided.
The purge passage 54 extending from the canister 51 branches into a first purge passage 54a and a second purge passage 54b.

The purge control valve 55 is, for example, a solenoid valve whose opening degree is adjusted by PWM control. The purge control valve 55 is provided on the upstream side of the branch portion between the first purge passage 54a and the second purge passage 54b, in other words, in the purge passage 54 between the branch portion of the purge passage 54 and the canister 51.
The first purge passage 54a communicates with the intake collector 22, in other words, the intake passage downstream of the throttle valve 26.

The second purge passage 54b communicates with the intake duct 23 between the air cleaner 24 and the compressor 25 of the turbocharger, in other words, the intake passage upstream of the throttle valve 26 via the ejector device 56.
One end of the second purge passage 54b and the return passage 57 is connected to the ejector device 56.

The other end of the recirculation passage 57 is connected to an intake duct 23 between the compressor 25 and the throttle valve 26, and the recirculation passage 57 guides the air compressed by the compressor 25 to the ejector device 56.
The ejector device 56 generates a negative pressure in the second purge passage 54b by the compressed air introduced through the return passage 57.

That is, in the supercharged state by the compressor 25, the pressure on the downstream side of the compressor 25 becomes high, and the evaporated fuel cannot be sucked from the canister 51 in the first purge passage 54a. Therefore, the negative pressure generated by the ejector device 56 causes the second purge passage 54b. Aspirate the evaporated fuel from.
Further, the air introduction passage 53 is provided with a leak diagnosis module 60 for diagnosing the presence or absence of a leak in the evaporated fuel treatment device 50.

As shown in FIG. 2, the leak diagnosis module 60 includes an electromagnetic switching valve 61, a bypass flow path 62, a vacuum pump 63, and a pressure sensor 64.
The switching valve 61 is a valve device for switching the path of the atmosphere introduction passage 53. In the off state shown in FIG. 2, the canister 51 and the atmosphere opening port 53a communicate with each other without passing through the vacuum pump 63, and in the on state, the vacuum pump The canister 51 and the atmosphere opening 53a are communicated with each other via 63.

The bypass flow path 62 is provided so as to bypass the path switched by the switching valve 61, and the bypass flow path 62 includes an orifice 62a.
The pressure sensor 64 is provided in the bypass flow path 62 between the vacuum pump 63 and the orifice 62a, and detects the pressure in the bypass flow path 62, in other words, the pressure PAO of the atmosphere opening 53a.

The control device 70 is an electronic control device having a built-in microcomputer 71. The microcomputer 71 includes an MPU (Microprocessor Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), performs an operation based on the input information, and outputs the calculated result.
Here, the control device 70 (microcomputer 71) controls the opening degree of the purge control valve 55, in other words, the evacuation purge control, and also uses the leak diagnosis module 60 to perform leak diagnosis of the evaporated fuel treatment device 50. Further, the fuel injection amount is controlled by the fuel injection valve 27.
It should be noted that the system can be a system in which the evaporative purge control, the leak diagnosis of the evaporated fuel treatment device 50, and the control of the fuel injection amount by the fuel injection valve 27 are shared by a plurality of electronic control devices.

A plurality of sensors for detecting the operating state of the internal combustion engine 10 are provided for various controls by the control device 70.
As a sensor for detecting the operating state of the internal combustion engine 10, a flow rate sensor 81 that outputs a signal corresponding to the intake air flow rate QA of the internal combustion engine 10 and a signal corresponding to the pressure PB (pressure of the intake passage) in the intake collector 22 are output. The air-fuel ratio sensor 82 that outputs a signal according to the air-fuel ratio AF of the internal combustion engine 10 based on the oxygen concentration in the exhaust upstream of the catalytic converter 28, and the air-fuel ratio sensor 83 that outputs a signal according to the rotation speed NE of the internal combustion engine 10. A rotation speed sensor 84 that outputs a signal, a water temperature sensor 85 that outputs a signal corresponding to the temperature TW of the cooling water of the internal combustion engine 10, an atmospheric pressure sensor 86 that outputs a signal corresponding to the atmospheric pressure AP around the internal combustion engine 10, etc. Is provided.

The following outlines one aspect of leak diagnosis performed by the control device 70 using the leak diagnosis module 60.
The control device 70 closes the purge control valve 55 and turns on the switching valve 61 while the internal combustion engine 10 is stopped, and then operates the vacuum pump 63 to release the air in the atmosphere introduction passage 53 to the atmosphere. The pressure is reduced in the path upstream of the purge control valve 55 (on the canister 51 side).

Here, if there is a leak in the path upstream of the purge control valve 55, air flows into the path from the leak portion, so that the pressure drop due to the drive of the vacuum pump 63 becomes smaller than in the case where there is no leak.
Therefore, the control device 70 detects the pressure change in the vaporized fuel processing path driven by the vacuum pump 63 based on the signal of the pressure sensor 64, diagnoses the presence or absence of a leak based on the detected pressure change, and saves the diagnosis result. At the same time, when the occurrence of a leak is diagnosed, an abnormality processing such as an alarm is executed.

The control device 70 calculates the basic fuel injection amount based on the intake air flow rate QA and the rotation speed NE in controlling the fuel injection amount by the fuel injection valve 27.
Further, the control device 70 calculates the air-fuel ratio feedback correction value (air-fuel ratio correction value) so that the air-fuel ratio detected by the air-fuel ratio sensor 83 approaches the target air-fuel ratio.

Further, the control device 70 supplies the evaporated fuel desorbed from the canister 51 by opening the purge control valve 55 to the intake passage of the internal combustion engine 10 in a state of supplying the evaporated fuel to the intake passage of the internal combustion engine 10 (purge state). The amount of evaporated fuel to be produced is obtained, and the purge fuel correction value is calculated based on the obtained amount of evaporated fuel.
Then, the control device 70 corrects the basic fuel injection amount with an air fuel ratio feedback correction value, a purge fuel correction value, or the like to obtain the final fuel injection amount, and a fuel injection command signal (fuel injection) based on the obtained fuel injection amount. The pulse signal) is output to the fuel injection valve 27.

Further, when the control device 70 opens the purge control valve 55 to desorb the evaporated fuel from the canister 51, the control device 70 sets the opening degree of the purge control valve 55 to the air-fuel ratio feedback correction value and the evaporated fuel in the canister 51. It is set based on the estimated value of the concentration, and a command signal corresponding to the set opening degree is output to the purge control valve 55.
FIG. 3 is a functional block diagram schematically showing the opening degree control of the purge control valve 55 and the correction control of the fuel injection amount in the purged state, which are carried out by the control device 70.

The block 101 measures the air-fuel ratio of the internal combustion engine 10 based on the detection signal of the air-fuel ratio sensor 83, and the block 102 is an air-fuel ratio feedback correction value (air-fuel ratio) for correcting the fuel injection amount based on the measured value of the air-fuel ratio. (Correction value) is calculated.
The block 103 calculates the evaporated fuel concentration deviation (evaporative concentration deviation) from the air-fuel ratio feedback correction value (mean value) and the control purge rate calculated in the block 104.

The evaporative fuel concentration deviation calculated in block 103 is given to the block 200 for estimating the evaporative fuel concentration in the canister 51.
Further, the block 104 obtains a control purge rate for obtaining the drive duty of the purge control valve 55 based on the evaporative fuel concentration in the canister 51 calculated by the block 200.

The block 105 obtains the intake air amount of the internal combustion engine 10 based on the detection signal of the flow rate sensor 81, and gives the information of the obtained intake air amount to the block 106.
The block 106 calculates the purge flow rate (flow rate of purge gas per unit time) based on the intake air amount and the control purge rate.

The block 107 calculates the deviation between the atmospheric pressure AP and the intake pipe pressure PB as the suction negative pressure of the evaporated fuel.
The block 108 obtains the control duty from the control purge rate.

The block 109 obtained the invalid component duty based on the deviation between the atmospheric pressure AP and the intake pipe pressure PB (intake negative pressure of the evaporated fuel) and the power supply voltage (battery voltage) of the purge control valve 55, and obtained it in the block 108. The addition result of the control duty and the invalid component duty is set as the final control duty.
The block 110 outputs a command signal for PWM control of energization of the purge control valve 55 based on the final control duty set in step S109, and sets the opening degree of the purge control valve 55 to the opening degree according to the control duty. Control.

On the other hand, the block 111 determines the fuel injection amount from the fuel injection valve 27 based on the control purge rate calculated in the block 104 and the estimated value of the evaporated fuel concentration in the intake passage obtained in the block 200 (block 205). The fuel correction amount to be reduced according to the amount of evaporated fuel supplied to the intake passage by the purge control is calculated.
Then, the block 112 changes the fuel injection amount by the fuel injection valve 27 based on the fuel correction amount calculated by the block 111 to suppress the change in the air-fuel ratio due to the purge.

Next, the arithmetic processing function in the block 200 will be outlined.
The block 201 measures the pressure PAO of the atmosphere introduction passage 53 that introduces the atmosphere into the canister 51 based on the detection signal of the pressure sensor 64 (the signal related to the pressure of the atmosphere introduction passage 53).

The block 202 measures the atmospheric pressure AP based on the detection signal (signal related to the atmospheric pressure) of the atmospheric pressure sensor 86.
The block 203 measures the intake pipe pressure PB based on the detection signal (signal related to the pressure of the intake passage) of the intake pipe pressure sensor 82.

The block 204 compares the intake pipe pressure PB or the atmospheric pressure AP with the pressure PAO of the atmosphere introduction passage 53 in the purge state in which the purge control valve 55 is opened and the evaporated fuel is desorbed from the canister 51. , Information on the ventilation resistance of the canister 51 is obtained, and the correction value of the adsorption amount of the evaporated fuel in the canister 51 is calculated based on the obtained information on the ventilation resistance.

The differential pressure between the intake pipe pressure PB or the atmospheric pressure AP and the pressure PAO of the atmosphere introduction passage 53 changes depending on the ventilation resistance of the canister 51, and the ventilation resistance of the canister 51 increases as the amount of evaporated fuel adsorbed increases. ..
That is, the block 204 estimates the amount of evaporative fuel adsorbed by the canister 51 by comparing the intake pipe pressure PB or the atmospheric pressure AP with the pressure PAO of the atmosphere introduction passage 53.

The block 205 integrates the value obtained by multiplying the evaporative fuel concentration deviation calculated in the block 103 by the gain to obtain the evaporative fuel concentration estimated value, and gives the information regarding the obtained concentration estimated value to the blocks 111 and 206.
The block 206 obtains the evaporative fuel concentration in the canister 51 based on the information on the correction value of the evaporated fuel adsorption amount obtained in the block 204 and the information on the estimated concentration obtained in the block 205, and obtains the information on the evaporated fuel concentration. Is output to the block 104.

In this way, the control device 70 obtains the concentration of the evaporated fuel based on the air-fuel ratio feedback correction value, and corrects the fuel injection amount (fuel supply amount) based on the obtained concentration of the evaporated fuel.
Further, the control device 70 compares the intake pipe pressure PB or the atmospheric pressure AP with the pressure PAO of the atmosphere introduction passage 53 to determine the amount of fuel vapor adsorbed by the canister 51 (in other words, the ventilation resistance of the canister 51). ), And the control purge rate (opening of the purge control valve 55) is changed based on the estimated adsorption amount (ventilation resistance) of the evaporated fuel.

FIG. 4 is a flowchart showing a processing procedure of the fuel injection amount correction function in the functional block diagram of FIG.
The control device 70 detects the actual air-fuel ratio of the internal combustion engine 10 from the output of the air-fuel ratio sensor 83 in step S501, and corrects the fuel injection amount so that the actual air-fuel ratio approaches the target air-fuel ratio in step S502. Calculate the air-fuel ratio feedback correction value of.

Then, the control device 70 obtains the average value of the air-fuel ratio feedback correction value in step S503, and calculates the EVAPO concentration deviation from the average value of the air-fuel ratio feedback correction value and the control purge rate in step S504.
Further, in step S505, the control device 70 integrates the evaporative concentration deviation to obtain an estimated value of the concentration of the evaporated fuel in the intake passage.

Next, in step S506, the control device 70 calculates a correction value for correcting the fuel injection amount of the fuel injection valve 27 based on the estimated concentration value of the evaporated fuel in the intake passage and the control purge rate. ..
Then, in step S507, the control device 70 outputs to the fuel injection valve 27 a command signal according to the estimated value of the concentration of the evaporated fuel in the intake passage and the fuel injection amount corrected based on the control purge rate, and fuels the fuel. The injection valve 27 causes the internal combustion engine 10 to inject.

FIG. 5 is a flowchart showing a processing procedure of the opening degree control function of the purge control valve 55 in the functional block diagram of FIG.
In step S601, the control device 70 detects the actual air-fuel ratio of the internal combustion engine 10 from the output of the air-fuel ratio sensor 83, and in step S602, corrects the fuel injection amount so that the actual air-fuel ratio approaches the target air-fuel ratio. Calculate the air-fuel ratio feedback correction value of.

Then, the control device 70 obtains the average value of the air-fuel ratio feedback correction value in step S603, and calculates the EVAPO concentration deviation from the average value of the air-fuel ratio feedback correction value and the control purge rate in step S604.
Further, in step S605, the control device 70 integrates the evaporation concentration deviation to obtain the estimated concentration value EEC of the evaporated fuel in the intake passage.

Further, the control device 70 acquires the detection signal of the atmospheric pressure sensor 86 in step S606, and obtains the atmospheric pressure AP based on the acquired detection signal.
In the next step S607, the control device 70 acquires the detection signal of the intake pipe pressure sensor 82, and obtains the intake pipe pressure PB based on the acquired detection signal.

In the next step S608, the control device 70 acquires the detection signal of the pressure sensor 64, and obtains the pressure PAO of the atmosphere introduction passage 53 of the canister 51 based on the acquired detection signal.
Then, in step S609, the control device 70 has a differential pressure ΔP1 (ΔP1 = PB-PAO) between the intake pipe pressure PB and the pressure PAO of the atmosphere introduction passage 53 in the purged state, or the atmospheric pressure AP and the atmosphere introduction passage 53. The differential pressure ΔP2 (ΔP2 = AP-PAO) from the pressure PAO of the above is obtained, and in the next step S610, the correction value KEC for correcting the concentration estimated value EEC is calculated based on the differential pressure ΔP1 or the differential pressure ΔP2.

FIG. 6 is a diagram showing the correlation between the differential pressure ΔP1 and the adsorption amount of the evaporated fuel in the canister 51.
The larger the differential pressure ΔP1, the larger the ventilation resistance of the canister 51, and the larger the adsorption amount of the evaporated fuel, the larger the ventilation resistance of the canister 51. That is, the larger the amount of evaporated fuel adsorbed by the canister 51, the larger the differential pressure ΔP1.

Therefore, the control device 70 estimates that the larger the differential pressure ΔP1 is, the larger the adsorption amount of the evaporated fuel in the canister 51 is, and the larger the adsorption amount of the evaporated fuel, the higher the concentration estimated value EEC is corrected to a higher concentration value. The correction value KEC is set so that the concentration estimation value EEC is corrected to a lower concentration value as the adsorption amount of the evaporated fuel is smaller.

FIG. 7 is a diagram showing the correlation between the differential pressure ΔP2 and the adsorption amount of the evaporated fuel in the canister 51.
The smaller the differential pressure ΔP2, the larger the ventilation resistance of the canister 51, and the larger the adsorption amount of the evaporated fuel, the larger the ventilation resistance of the canister 51. That is, the larger the amount of evaporated fuel adsorbed by the canister 51, the smaller the differential pressure ΔP2.

Therefore, the control device 70 estimates that the smaller the differential pressure ΔP2, the larger the adsorption amount of the vaporized fuel in the canister 51, and the larger the adsorption amount of the evaporated fuel, the higher the concentration estimated value EEC is corrected to a higher concentration value. The correction value KEC is set so that the concentration estimation value EEC is corrected to a lower concentration value as the adsorption amount of the evaporated fuel is smaller.
Since the pressure PAO of the atmosphere introduction passage 53 is lower than the atmospheric pressure, the atmosphere (air, outside air) flows into the atmosphere introduction passage 53, and the air flowing into the atmosphere introduction passage 53 passes through the canister 51. ..

Here, if the amount of evaporated fuel adsorbed by the canister 51 is large and the ventilation resistance of the canister 51 is large, the differential pressure ΔP2 becomes small, and the amount of air flowing into the atmosphere introduction passage 53 decreases.
Therefore, it can be estimated that the smaller the differential pressure ΔP2 of the control device 70, the larger the adsorption amount of the evaporated fuel in the canister 51 and the larger the ventilation resistance of the canister 51.

When the control device 70 obtains the correction value KEC in step S610, it proceeds to step S611, corrects the concentration estimated value EEC obtained in step S605 with the correction value KEC, and corrects the concentration estimated value of the evaporated fuel in the canister 51. Find the ECCC.
Here, in the control device 70, even if the estimated concentration value EEC of the evaporated fuel in the intake passage is the same, the larger the adsorption amount of the evaporated fuel in the canister 51 and the larger the ventilation resistance of the canister 51, the greater the evaporation fuel in the canister 51. The concentration estimate of ECCC will be estimated higher.

In the next step S612, the control device 70 calculates the control purge rate, which is the ratio of the purge flow rate to the intake air flow rate of the internal combustion engine 10, based on the concentration estimated value ECCC.
Next, in step S613, the control device 70 acquires the detection signal of the flow rate sensor 81, and obtains the intake air flow rate QA based on the acquired detection signal.

Then, in step S614, the control device 70 estimates the purge flow rate based on the control purge rate and the intake air flow rate QA.
Further, in step S615, the control device 70 obtains the suction negative pressure (suction negative pressure = atmospheric pressure AP-atmospheric pressure AP-intake pipe pressure PB) acting on the canister 51 based on the intake pipe pressure PB and the atmospheric pressure AP.

In step S616, the control device 70 obtains the control duty of the purge control valve 55 for realizing the control purge rate based on the suction negative pressure acting on the canister 51 and the estimated value of the purge flow rate.
Next, the control device 70 proceeds to step S617, outputs a command signal for PWM control of energization of the purge control valve 55 based on the control duty obtained in step S616, and opens the purge control valve 55 according to the control duty. Drive every time.

Here, the control device 70 corrects the concentration estimated value EEC higher and changes the control purge rate smaller as the differential pressure ΔP1 is larger and the adsorption amount of the vaporized fuel in the canister 51 is estimated to be larger. The larger the differential pressure between the pressure PAO of the air introduction passage of the canister 51 and the intake pipe pressure PB, the smaller the opening degree of the purge control valve 55 is changed.
On the other hand, the control device 70 corrects the concentration estimated value EEC higher and changes the control purge rate smaller as the differential pressure ΔP2 is smaller and the adsorption amount of the vaporized fuel in the canister 51 is estimated to be larger. The smaller the differential pressure between the pressure PAO of the air introduction passage of the canister 51 and the atmospheric pressure AP, the smaller the opening degree of the purge control valve 55 is changed.

Hereinafter, the operation and effect of the purge control by the control device 70, specifically, the correction processing of the concentration estimated value EEC based on the differential pressure ΔP1 or the differential pressure ΔP2 will be described.
FIG. 8 shows a case where the control device 70 does not perform the correction processing of the concentration estimated value EEC based on the differential pressure ΔP1 or the differential pressure ΔP2, in other words, the case where the purge control according to the amount of adsorbed fuel of the canister 51 is not performed. It is a time chart exemplifying changes in air-fuel ratio, concentration estimated value, control duty, engine rotation speed, etc. due to changes in engine load.

When the suction negative pressure of the internal combustion engine 10 decreases as the engine load increases at time t11 in FIG. 8, when the amount of evaporated fuel adsorbed by the canister 51 is large and the ventilation resistance of the canister 51 is large, the combustion chamber of the internal combustion engine 10 There will be more reduction in the evaporative fuel flowing into 15.
Since the air-fuel ratio becomes lean when the amount of fuel vapor flowing into the combustion chamber 15 decreases, the control device 70 reduces the amount of reduction correction of the fuel injection amount by the fuel injection valve 27, and changes the concentration estimated value EEC to a low value. The opening degree of the purge control valve 55 will be increased.

When the suction negative pressure of the internal combustion engine 10 increases as the engine load decreases at time t12 from this state, the opening degree of the purge control valve 55 is increased, so that a large amount of evaporated fuel flows into the combustion chamber 15. The air-fuel ratio becomes overrich, and unstable combustion causes rotational fluctuations.
That is, when the control device 70 does not perform the correction processing of the concentration estimated value EEC based on the differential pressure ΔP1 or the differential pressure ΔP2, the opening degree of the purge control valve 55 is set to the opening degree corresponding to the adsorption amount of the evaporated fuel in the canister 51. It cannot be controlled, and it is difficult to prevent a large amount of evaporated fuel from flowing into the combustion chamber 15 and overriching the air-fuel ratio due to fluctuations in the engine load.

On the other hand, FIG. 9 shows changes in the air-fuel ratio, concentration estimated value, control duty, engine rotation speed, etc. due to changes in the engine load when the correction process of the concentration estimated value EEC based on the differential pressure ΔP1 or the differential pressure ΔP2 is performed. It is a time chart exemplifying.
The control device 70 sequentially obtains the differential pressure ΔP1 or the differential pressure ΔP2 in the purged state, and sets the correction value KEC according to the adsorption amount of the evaporated fuel in the canister 51.

Then, when the amount of the evaporated fuel adsorbed by the canister 51 is large, in other words, when the ventilation resistance of the canister 51 is large, the control device 70 corrects the concentration estimated value EEC to be larger, so that the evaporated fuel in the canister 51 When the suction amount is large, the opening degree of the purge control valve 55 is changed to be smaller than when the suction amount is small.
Therefore, in the example of FIG. 9, even if the suction negative pressure decreases at time t21 and the amount of evaporated fuel purged from the canister 51 decreases, when the amount of evaporated fuel adsorbed by the canister 51 is large, it is compared with when it is small. The increase in the opening degree of the purge control valve 55 is suppressed.

Therefore, when the suction negative pressure increases at time t22, even if the amount of evaporated fuel adsorbed by the canister 51 is large, the amount of evaporated fuel flowing into the combustion chamber 15 rapidly increases and the air-fuel ratio becomes overrich. Is suppressed, and the occurrence of rotation fluctuations due to overriching of the air-fuel ratio is suppressed.
That is, the control device 70 corrects the concentration estimated value EEC based on the differential pressure ΔP1 or the differential pressure ΔP2, so that the opening degree of the purge control valve 55 is changed according to the adsorption amount of the evaporated fuel in the canister 51. It is possible to suppress fluctuations in the air-fuel ratio due to changes in the engine load (intake negative pressure of evaporated fuel).

The technical ideas described in the above embodiments can be used in combination as appropriate as long as there is no contradiction.
Moreover, although the content of the present invention has 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, the internal combustion engine 10 may be a naturally aspirated engine without a supercharger, and in the naturally aspirated engine, the second purge passage 54b, the ejector device 56, and the reflux passage 57 are omitted.
Further, the vaporized fuel processing device 50 may be provided with a pressure sensor for detecting the pressure PAO of the atmosphere introduction passage 53 without providing the leak diagnosis module 60.

Further, when the control device 70 obtains the differential pressure ΔP1 between the intake pipe pressure PB and the pressure PAO of the atmosphere introduction passage 53, the atmospheric pressure sensor 86 can be omitted, and the atmospheric pressure AP and the pressure PAO of the atmosphere introduction passage 53 can be omitted. When obtaining the differential pressure ΔP2 of, the intake pipe pressure sensor 82 can be omitted.
Further, the control device 70 obtains a ratio or a ratio instead of obtaining a differential pressure as a comparison process between the intake pipe pressure PB or the atmospheric pressure AP and the pressure PAO of the atmosphere introduction passage 53, and purge control is performed based on the obtained ratio or ratio. The opening degree of the valve 55 can be controlled.

Further, in the purged state in which the purge control valve 55 is opened, the control device 70 compares the intake pipe pressure PB or the atmospheric pressure AP with the pressure PAO of the atmosphere introduction passage 53 to obtain the ventilation resistance (evaporation) of the canister 51. When the pressure in the fuel tank 30 is changed by the pump, as disclosed in Japanese Patent Application Laid-Open No. 2005-139955, in the purge stopped state in which the fuel adsorption amount) is detected and the purge control valve 55 is closed. The ventilation resistance of the canister 51 can be detected based on the pressure change.

Further, the control device 70 estimates the ventilation resistance (adsorption amount of evaporated fuel) of the canister 51 by comparing the intake pipe pressure PB and the pressure PAO of the atmosphere introduction passage 53, and also estimates the atmospheric pressure AP and the atmosphere introduction passage 53. The ventilation resistance (adsorption amount of evaporated fuel) of the canister 51 is estimated by comparing with the pressure PAO, and based on these two estimation results, the ventilation resistance (adsorption amount of vaporized fuel) used for controlling the opening degree of the purge control valve 55 ) Can be obtained.

10 ... Internal combustion engine, 22 ... Intake collector, 23 ... Intake duct, 30 ... Fuel tank, 50 ... Evaporated fuel processing device, 51 ... Canister, 52 ... Evaporated fuel passage, 53 ... Atmospheric introduction passage, 54 ... Purge passage, 55 ... Purge control valve, 60 ... leak diagnosis module, 64 ... pressure sensor, 70 ... control device, 71 ... microcomputer, 82 ... intake pipe pressure sensor, 83 ... air-fuel ratio sensor, 86 ... atmospheric pressure sensor

Claims (4)

A canister that adsorbs evaporative fuel and
An evaporative fuel passage that connects the canister and the fuel tank of the internal combustion engine,
An atmosphere introduction passage that introduces the atmosphere into the canister,
A purge passage that communicates the canister and the intake passage of the internal combustion engine,
A purge control valve provided in the purge passage and
A control device applied to the evaporative fuel processing device having the above.
Obtain a signal regarding the pressure of the air introduction passage and
Obtaining a signal related to the pressure of the intake passage or a signal related to the atmospheric pressure,
With the purge control valve open, information on the amount of fuel adsorbed in the canister is obtained based on the signal regarding the pressure of the intake passage or the signal regarding the atmospheric pressure and the signal regarding the pressure of the atmosphere introduction passage.
A command signal for the opening degree of the purge control valve is obtained based on the information regarding the fuel adsorption amount.
Output the command signal,
Control device for evaporative fuel processing equipment. Obtaining a signal related to the air-fuel ratio correction value obtained based on the air-fuel ratio detection signal of the internal combustion engine,
A command signal for the opening degree of the purge control valve is obtained based on the signal regarding the air-fuel ratio correction value and the information regarding the fuel adsorption amount.
The control device for the evaporated fuel treatment device according to claim 1. The larger the difference between the pressure in the air introduction passage and the pressure in the intake passage, the smaller the opening degree of the purge control valve is changed.
The control device for the evaporative fuel processing device according to claim 1 or 2. The smaller the difference pressure between the pressure in the atmosphere introduction passage and the atmospheric pressure, the smaller the opening degree of the purge control valve is changed.
The control device for the evaporative fuel processing device according to claim 1 or 2.