JPH07166976A - Evaporative fuel treatment system of engine - Google Patents

Abstract

PURPOSE:To accelerate warm-up of a catalyst by making effective use of a highly volatile purge gas. CONSTITUTION:An activation means 44 activates an oxygen concentration sensor 42 at early stages using a heating means 43 at start-up, and a correction means 45 performs feedback compensation of an air-fuel ratio according to an output of the sensor 42 so that the air-fuel ratio coincides with a stoichiometric air-fuel ratio when water temperature is low before warm-up of a catalyst is complete. A valve opening means 48 opens a purge valve 46 when the judgment result of a judgment means 47 indicates a purging condition. When the judgment result of the judgment means 49 indicates that purging is under way and water temperature is low before warm-up of the catalyst is complete, a calculation means 50 retards a fundamental ignition timing ADV0 according to an operating condition signal, thereby calculating an ignition timing ADV.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine fuel vapor treatment system.

[0002]

2. Description of the Related Art In order to prevent the fuel vaporized from a fuel tank from being released to the atmosphere, a fuel vapor is adsorbed on an activated carbon canister, which is purged into an intake pipe together with fresh air under a predetermined operating condition. Some are burned inside (see Japanese Patent Laid-Open No. 4-94444).

In this case, Ti = Tp × α × K-KPG (1) where Tp: basic injection pulse width α: air-fuel ratio feedback correction coefficient K: constant KPG: purge correction amount , The purge correction amount K in the second term on the right side of the equation that gives the fuel injection pulse width Ti given to the injector.
By introducing PG, the amount of fuel injected from the injector is controlled so that the exhaust air-fuel ratio matches the theoretical air-fuel ratio even during purging.

The purge correction amount KPG has a value other than 0 during the air-fuel ratio feedback correction and during the purge. When this condition is satisfied, when α is less than 1.0 and the O ₂ sensor output indicates the rich side, the air-fuel ratio becomes rich due to the purge gas (that is, the fuel concentration of the purge gas is high. ), The purge correction amount KPG
Is increased by a predetermined value to correct the fuel injection pulse width of the first term by decreasing. On the contrary, when α exceeds the predetermined value and the O ₂ sensor output is on the lean side, the purge correction amount K
The PG is decreased by a predetermined amount to increase the fuel injection pulse width of the first term.

[0005]

By the way, since the exhaust performance becomes better when the feedback correction of the air-fuel ratio is started as soon as possible after the engine is started, the cooling water temperature Tw is kept at a predetermined value (for example, 25 ° C. or less) when the temperature is low. The fuel ratio feedback correction may be started.

This is made possible by activating the O ₂ sensor early by heating the heater at the same time as starting, rather than waiting for the O ₂ sensor to be heated and activated by the exhaust gas.

However, it cannot be said that the catalyst is activated in the low water temperature state of 25 to 60 ° C. immediately after the start of the feedback correction of the air-fuel ratio, and the ability of the catalyst cannot be fully brought out.

In this case, when the above purge gas is introduced, the combustion state at low water temperature is improved by the purge gas having high volatility, and the exhaust temperature rises if the ignition timing is retarded by this combustion improvement. Therefore, warming up of the catalyst can be promoted.

On the other hand, there is a lean burn engine in which the target air-fuel ratio is set to a value leaner than the stoichiometric air-fuel ratio under lean conditions in order to improve fuel efficiency, and the engine is operated at this lean side target air-fuel ratio. Even in this lean burn engine, if the purge gas is introduced under lean conditions, the target air-fuel ratio can be set to the lean side by the amount of improvement in combustion, thereby further improving fuel efficiency. Similarly, when the purge gas is introduced into the EGR, the EGR rate can be increased and NOx can be reduced by the increased amount.

However, the above-mentioned device does not touch upon low water temperature during lean-back correction of the air-fuel ratio, lean burn engine, and EGR control.

Therefore, an object of the present invention is to promote the warm-up of the catalyst and improve the fuel consumption and the exhaust performance by effectively utilizing the purge gas having high volatility.

[0012]

The first invention, as shown in FIG. 1, is a basic ignition timing ADV corresponding to an operating condition signal.
A means 41 for calculating 0, a sensor 42 for detecting the oxygen concentration in the exhaust gas, a means (for example, a heater) 43 for heating the sensor 42, and the heating means 43 are used to activate the sensor 42 at an early stage. Means 44 for changing the air-fuel ratio to a stoichiometric air-fuel ratio based on the sensor output so that the air-fuel ratio matches the stoichiometric air-fuel ratio from a low water temperature before the catalyst is warmed up, and the fuel adsorbed in the canister. Purge valve 46 that opens and closes a passage for introducing the air into the intake pipe together with fresh air according to a drive signal and whether the purge condition is the low water temperature during the air-fuel ratio feedback correction and before the completion of warming up of the catalyst. Means 47 for determining whether the purge valve 46 is opened under the purge condition based on the determination result, Means 49 for determining whether or not the low water temperature is before the air completion, and based on the result of the determination, the basic ignition timing ADV0 is retarded to correct the ignition timing ADV during the purging and the low water temperature before the completion of the warming up of the catalyst. And a means 51 for outputting an ignition signal to the ignition device 52 so that a spark will fly at this ignition timing ADV.

As shown in FIG. 25, the second aspect of the present invention includes means 41 for calculating the basic ignition timing ADV0 according to the operating condition signal, and a sensor 42 for detecting the oxygen concentration in the exhaust gas.
Means (for example, a heater) 4 for heating the sensor 42
3 and the sensor 4 at the time of starting using this heating means 43.
Means 44 for activating 2 early, and means 61 for calculating the air-fuel ratio feedback correction coefficient α based on the sensor output so that the air-fuel ratio matches the theoretical air-fuel ratio from the low water temperature before the completion of warming up of the catalyst. , Means 62 for calculating the fuel injection amount by correcting the basic injection amount Tp according to the operating condition signal with this feedback correction coefficient α, a device 63 for supplying this injection amount of fuel to the intake pipe, and adsorbing it to the canister. The purge valve 64 for adjusting the flow rate of the passage for introducing the fuel to the intake pipe together with the fresh air according to the drive signal, and the purge condition under the low water temperature during the air-fuel ratio feedback correction and before the completion of the warming up of the catalyst. Means 47 for judging whether or not the condition is satisfied, and means for calculating the purge valve opening PV from the fuel concentration A in the purge gas under the purge condition based on the result of the judgment. 65 and the purge valve opening PV
Means 66 for outputting a drive signal according to the above to the purge valve 64, means 67 for determining whether the purge is being performed and the air-fuel ratio feedback correction is being performed, and the purge result is being determined and the air-fuel ratio feedback correction is being performed. Means 68 for calculating the fuel concentration A in the purge gas on the basis of the air-fuel ratio feedback correction coefficient α and the purge valve opening PV, and the completion of warming up of the catalyst during purging and during the air-fuel ratio feedback correction. A means 69 for determining whether or not the previous low water temperature is present, and a fuel concentration A in the purge gas at the time of low water temperature before purging and during the air-fuel ratio feedback correction and before completion of warming up of the catalyst based on the result of this determination. a means 70 for calculating a fuel ratio R _EVAP purge gas based on said air-fuel ratio feedback correction coefficient alpha, this Retard correction amount ΔADV be large enough which increases according to the fuel ratio R _EVAP purge gas
And a means 72 for calculating the ignition timing ADV by retarding the basic ignition timing ADV0 with the retard correction amount ΔADV, and an ignition device 52 for igniting a spark at the ignition timing ADV. And a means 51 for outputting a signal.

A third aspect of the invention is the fuel cell system according to the second aspect of the invention, in which the purge valve opening amount is increased and corrected at a low water temperature before the completion of warming up of the catalyst.

As shown in FIG. 26, the fourth aspect of the present invention is the basic value Tfbya0 of the lean side target air-fuel ratio under lean conditions.
And a purge valve 46 that opens and closes a passage for introducing the fuel adsorbed in the canister into the intake pipe together with the fresh air according to the driving signal.
Means 82 for determining whether or not the lean condition is the purge condition by using the lean condition as the purge condition, and means 48 for opening the purge valve 46 under the purge condition based on the result of the determination.
And a means 83 for determining whether or not the purge is in the lean condition, and based on the determination result, the target air-fuel ratio Tfbya is corrected by correcting the basic value Tfbya0 of the target air-fuel ratio to the lean side in the purge and the lean condition. Calculation means 8
4, means 85 for calculating the fuel injection amount under the lean condition by correcting the basic injection amount Tp according to the operating condition signal with the target air-fuel ratio Tfbya, and a device for supplying the fuel of this injection amount to the intake pipe. 63 and 63 are provided.

As shown in FIG. 27, the fifth aspect of the present invention is based on a sensor 42 for detecting the oxygen concentration in the exhaust gas, and based on the output of this sensor, the exhaust air-fuel ratio is the theoretical air-fuel ratio under the non-lean condition and the air-fuel ratio feedback condition. A means 91 for calculating the air-fuel ratio feedback correction coefficient α so as to match the fuel ratio, a purge valve 64 for adjusting the flow rate of the passage for introducing the fuel adsorbed in the canister together with the fresh air into the intake pipe, and the lean valve 64. Means 81 for calculating the basic value Tfbya0 of the lean side target air-fuel ratio in accordance with the operating condition signal under the conditions
And a means 92 for determining whether the lean condition is the first purge condition, and the low load after the completion of warming up of the engine during the air-fuel ratio feedback correction is the second purge condition as the second purge condition. From this determination result, means 65 for calculating the opening PV of the purge valve from the fuel concentration A in the purge gas under the purge condition, and the purge valve opening P
Means 66 for outputting a drive signal according to V to the purge valve 64; means 93 for determining whether or not purging under the second purge condition, the non-lean condition, and the air-fuel ratio feedback correction are being performed. From this determination result, the fuel concentration in the purge gas is based on the air-fuel ratio feedback correction coefficient α and the purge valve opening PV during the purge under the second purge condition, the non-lean condition and the air-fuel ratio feedback correction. A means 94 for calculating A, a means 95 for determining whether the purge is under the first purge condition and the lean condition, and a purge result under the first purge condition and the lean condition based on the determination result. Under the conditions, the fuel ratio R _{E of the} purge gas is based on the fuel concentration A in the purge gas and the basic value Tfbya0 of the target air-fuel ratio. A means 96 for calculating a _VAP, means for calculating the air-fuel ratio correction amount ΔTfbya this becomes more larger decreases according to the fuel ratio R _EVAP this purge gas 97
And the target air-fuel ratio T by correcting the basic value Tfbya0 of the target air-fuel ratio to the lean side by the air-fuel ratio correction amount ΔTfbya.
fbya calculation means 98, and the target air-fuel ratio T during purging under the first purge condition and under the lean condition.
fbya, the non-lean condition and the air-fuel ratio feedback condition, the air-fuel ratio feedback correction coefficient α
A means 99 for calculating the fuel injection amount by correcting the basic injection amount corresponding to the operating condition signal, and a device 63 for supplying the fuel of this injection amount to the intake pipe are provided.

The sixth invention, as shown in FIG. 28, is an EGR valve 111 whose opening changes according to a drive signal.
And means 112 for calculating the basic EGR valve opening degree V _EGR 0 according to the operating condition signal under the EGR condition, and a passage for introducing the fuel adsorbed in the canister with the fresh air into the intake pipe according to the drive signal. A purge valve 46, a means 113 for determining whether or not this is the purge condition with the inside of the EGR as a purge condition, a means 48 for opening the purge valve 46 under the purge condition based on the determination result, and a state of purging and during the EGR. A means 114 for determining whether or not, and based on the result of this determination, the basic EGR valve opening degree V _EGR 0 is increased and corrected during purging and during EGR.
Means 115 for calculating the GR valve opening degree V _EGR , and E
Means 116 for outputting a signal corresponding to the GR valve opening degree V _EGR to the EGR valve 111 is provided.

The seventh invention is, as shown in FIG. 29, E
Means 112 for calculating the basic EGR valve opening degree V _EGR 0 according to the operating condition signal under the GR condition, the sensor 42 for detecting the oxygen concentration in the exhaust gas, and the exhaust air-fuel ratio as the theoretical air-fuel ratio based on the sensor output. Means 91 for calculating the air-fuel ratio feedback correction coefficient α so that they coincide with each other, and the basic injection amount T corresponding to the operating condition signal with this feedback correction coefficient α
A means 62 for correcting p to calculate a fuel injection amount, a device 63 for supplying the injection amount of fuel to the intake pipe, and a flow rate of a passage for introducing the fuel adsorbed in the canister with fresh air into the intake pipe. Purge valve 64 that adjusts according to the signal
And means 121 for determining whether or not the purge condition is the purge condition while the EGR is being performed and the air-fuel ratio feedback correction is being performed, and based on the determination result, from the fuel concentration A in the purge gas to the purge valve opening PV under the purge condition.
And means 6 for outputting a drive signal corresponding to the purge valve opening PV to the purge valve 64.
6 and means 122 for determining whether the purge is being performed, the air-fuel ratio feedback correction is being performed, and the EGR is being performed.
And a means 12 for calculating the fuel concentration A in the purge gas based on the air-fuel ratio feedback correction coefficient α and the purge valve opening PV during purging, during the air-fuel ratio feedback correction and during the EGR based on the determination result.
3 and means 124 for calculating the fuel ratio R _{EVAP of the} purge gas based on the fuel concentration A in the purge gas and the air-fuel ratio feedback correction coefficient α during the purge, during the air-fuel ratio feedback correction and during the EGR, A means 12 for calculating an opening correction amount ΔV _EGR that increases according to the fuel ratio R _{EVAP of the} purge gas.
5, a means 126 for calculating the EGR valve opening degree V _EGR the basic EGR valve opening V _EGR 0 in this opening correction amount [Delta] V _EGR increasing correction to the signal corresponding to the EGR valve opening V _EGR Means 11 for outputting to the EGR valve 111
6 and 6 are provided.

[0019]

Since the purge gas is highly volatile, if the purge gas is mixed into the intake pipe in addition to the fuel from the fuel supply device, the combustion characteristics in the combustion chamber will be improved. Even if it is kept constant, the surge limit expands in the retard direction of the ignition timing.

By utilizing this characteristic, when the ignition timing is retarded at the low water temperature during the purging and before the completion of the catalyst warm-up in the first aspect of the invention, the exhaust performance is improved as much as the exhaust temperature rises. In addition, no surge occurs.

In the second aspect of the invention, the fuel concentration A in the purge gas is calculated based on the air-fuel ratio feedback correction coefficient α and the purge valve opening PV during the purge and during the air-fuel ratio feedback correction. The fuel concentration A in the purge gas and the air-fuel ratio feedback correction coefficient α during the feedback correction and the low water temperature before the completion of the warming up of the catalyst
The fuel ratio R _{EVAP of the} purge gas is calculated based on the above, and the retard correction amount ΔADV that increases as the fuel ratio R _{EVAP of the} purge gas increases is calculated.
When the basic ignition timing ADV0 is retarded by this retard correction amount ΔADV, in addition to the effect of the first aspect of the invention, the retard correction amount ΔADV is given without excess or deficiency even if the fuel concentration A in the purge gas is different. To be

In the third invention, when the purge valve opening amount is increased and corrected at a low water temperature before the catalyst has been warmed up, the ignition timing retard correction amount is further increased, and in addition to the function of the second invention. The catalyst warm-up is further promoted.

According to the fourth aspect of the present invention, when the purge gas is introduced under lean conditions and the target air-fuel ratio is corrected to the lean side during this purge, fuel consumption is improved and surge occurs due to the combustion improvement due to introduction of the purge gas. Nor.

In the fifth aspect of the present invention, the lean condition is the first purge condition, and the second purge condition is a low load after completion of warm-up of the engine during air-fuel ratio feedback correction, and the purge is performed under the second purge condition. During the medium and non-lean conditions and the air-fuel ratio feedback correction, the fuel concentration A in the purge gas is calculated based on the air-fuel ratio feedback correction coefficient α and the purge valve opening PV, and the purge condition under the first purge condition and the lean condition are satisfied. basic value of the fuel concentration a and the target air-fuel ratio in the purge gas on the basis of the Tfbya0 fuel ratio R _EVAP purge gas is calculated, the fuel ratio R _EVAP this purge gas
A / F ratio correction amount Δ
Tfbya is calculated, and this air-fuel ratio correction amount ΔTfbya is calculated.
When the basic value Tfbya0 of the target air-fuel ratio is corrected to the lean side, the air-fuel ratio correction amount ΔTfbya is given just enough even if the fuel concentration A in the purge gas is different, in addition to the effect of the fourth invention.

In the sixth invention, when the purge gas is introduced into the EGR and the EGR valve opening is increased during the purge,
Since the EGR rate increases as much as the combustion improvement due to the introduction of the purge gas, the combustion temperature decreases and the NOx emission amount decreases.

In the seventh aspect of the invention, the fuel concentration A in the purge gas is calculated based on the air-fuel ratio feedback correction coefficient α and the purge valve opening PV during purging, air-fuel ratio feedback correction and EGR. The fuel ratio R _{EVAP of the} purge gas is calculated based on the fuel concentration A and the air-fuel ratio feedback correction coefficient α, and the opening correction amount ΔV _EGR that increases as the fuel ratio R _{EVAP of the} purge gas increases is calculated. When in degrees correction amount [Delta] V _EGR basic EGR valve opening V _EGR 0 is corrected to increase, in addition to the effect of the sixth invention, the opening correction amount [Delta] V _EGR also fuel concentration a in the purge gas is different over- Given without any shortage. Three

[0027]

In FIG. 2, the air sucked from the air cleaner 3 is temporarily stored in a collector portion 2a having a constant volume and then flows into each cylinder through a branch pipe. An injector 4 is provided at the intake port 2b of each cylinder, and fuel is intermittently injected from the injector 4 in synchronization with the engine rotation. The air-fuel mixture formed from the injected fuel and air is compressed by the piston in the combustion chamber and burns with the help of sparks emitted from the spark plug.

The longer the injection time from the injector 4, the larger the injection amount, and the shorter the injection time, the smaller the injection amount. The richness of the air-fuel mixture, that is, the air-fuel ratio, shifts to the rich side when the fuel injection amount for a fixed amount of intake air increases, and shifts to the lean side when the fuel injection amount decreases. Therefore, if the control unit 11 determines the basic fuel injection flow rate so that the ratio to the intake air flow rate becomes a constant value, the same air-fuel ratio can be obtained even under different operating conditions. When the fuel is intermittently injected once per one revolution of the engine, the basic injection pulse width Tp is calculated from the intake air flow rate Qa and the engine speed Ne at that time with respect to the amount of air sucked in one revolution by Tp. = (Qa / Ne) × K # (2) where K # is a constant that determines the basic air-fuel ratio. Usually, the air-fuel ratio determined by this Tp is near the stoichiometric air-fuel ratio.

In the exhaust pipe 5, CO discharged from the combustion chamber,
A catalyst (three-way catalyst) 6 for treating three harmful components such as HC and NOx is provided. The catalyst 6 can efficiently treat harmful three components simultaneously only when the exhaust air-fuel ratio is in a narrow range centered on the stoichiometric air-fuel ratio. In order to keep the air-fuel ratio within this range, the control unit 11 feedback-corrects the fuel injection amount from the injector 4 based on the output of the O ₂ sensor 7 provided upstream of the catalyst 6.

However, from the start of the engine to immediately after that, the air-fuel ratio feedback correction is not performed, but the combustion state is improved by the water temperature increase correction and the post-start increase correction to give priority to the drivability.

The general formula of the fuel injection pulse width Ti given to the injector 4 is as follows: Ti = Tp × CO × α + Ts (3) where CO; 1 and the sum of various correction coefficients α; air-fuel ratio feedback correction coefficient Ts ; Invalid pulse width. From the start of the engine to immediately after that, α = 1
From 00%, Ti = Tp × (1 + Ktw + Kas) + Ts where Ktw: water temperature increase correction coefficient Kas: post-starting increase correction coefficient, and when the air-fuel ratio feedback condition is satisfied, the fuel injection pulse is Ti = Tp × α + Ts The width Ti is calculated.

The actuator for ignition timing control is a power transistor 8 for turning on and off the primary current of the ignition coil. When the power transistor 8 is turned on by a signal from the control unit 11, the primary current flows and when it is turned off. The primary current is cut off and sparks fly. Therefore, the ignition timing is the timing at which the power transistor 8 is turned off.

In the control unit 11, the crank angle sensor 12 outputs the crank angle reference signal Ref.
(For example, a signal that rises at 66 ° before compression top dead center) and a 1 ° signal for each unit angle are input, and in order to ignite at 30 ° before compression top dead center, the reference signal Ref is received. At the same time, after counting the 1 ° signal 36 (= 66-30) times, the power transistor 8 is turned off.

On the other hand, the fuel evaporated in the fuel tank 21 is guided to the canister 23 through the passage 22 while the engine is stopped, and is adsorbed by the activated carbon in the canister 23. Reference numeral 24 is a check valve that prevents a backflow from the canister 23 to the fuel tank 21.

The canister 23 communicates with the intake pipe 2 downstream of the intake throttle valve 25 via a passage 26, and the passage 2
6, a normally closed purge valve 27 driven by a step motor is provided.

When the purge valve 27 is opened in response to the signal from the control unit 11, fresh air is introduced from the fresh air introduction passage 23a provided in the lower portion of the canister 23 due to the suction negative pressure developing downstream of the intake throttle valve 25. It is led into 23. The vaporized fuel separated from the activated carbon by this fresh air is purged into the intake pipe 2 together with the fresh air and burned in the combustion chamber.

The reason why the normally closed diaphragm actuator 28 is provided in series with the purge valve 27 is for fail-safe in case of failure of the purge valve 27. When the purge valve 27 is opened due to a failure, the purge gas (a mixed gas of the vaporized fuel separated from the activated carbon and the fresh air) is introduced even during warm-up, so that the air-fuel mixture becomes rich. Become. Therefore, under the non-purging condition, the normally closed diaphragm actuator 28 causes the passage 2 to pass through.
By shutting off 6, the purge gas is prevented from being introduced into the intake pipe 2 except under the purge condition.

It should be noted that the purge cut valve 2 is operated under the purge condition.
9 are opened simultaneously, and the suction negative pressure downstream of the throttle valve 25 is passed through the passage 30.
When it is guided to (the negative pressure operating chamber of) the diaphragm actuator 28 via, the diaphragm is pulled against the return spring by this negative pressure, and the passage 26 is opened.

By the way, the above-mentioned O ₂ sensor 7 is provided with a heater (heating means), and the control unit 11 does not wait for the O ₂ sensor 7 to be heated and activated by the exhaust gas. By activating the O ₂ sensor 7 early, the feedback correction of the air-fuel ratio is started from the time when the cooling water temperature Tw is as low as 25 ° C. or lower. At the start of the feedback correction, the water temperature increase correction and the after-start increase correction are completed.

However, it cannot be said that the catalyst 7 is activated in the low water temperature state of 25 to 60 ° C. immediately after the start of the air-fuel ratio feedback correction, and the ability of the catalyst 7 cannot be fully brought out.

In order to deal with this, the control unit 11 introduces a purge gas under a low water temperature purge condition during air-fuel ratio feedback correction to improve the combustion state at a low water temperature by the purge gas having high volatility,
By retarding the ignition timing by the amount of this combustion improvement, the exhaust temperature is raised and the catalyst warm-up is promoted.

The sensor required for such control is the same as the sensor required for normal air-fuel ratio control and ignition timing control, and detects the air flow meter 13 that outputs according to the intake air flow rate and the cooling water temperature Tw. The signal from the sensor 14 is input to the control unit 11 including a microcomputer together with the signals from the crank angle sensor 12 and the O ₂ sensor 7.

FIG. 3 is a flow chart showing the control of the purge valve 27 and the purge cut valve 29, FIG. 7 is a flow chart showing the calculation of the fuel concentration in the purge gas, and FIG. 9 is a flow chart showing the calculation of the ignition timing. These are shown at regular intervals (for example, 100 msec). 3 → FIG. 7 → FIG. 9 are executed in this order.

First, in FIG. 3, in step 1, the cooling water temperature Tw, the engine speed Ne, and the intake air flow rate Qa are read. These values are read at once for use in any of FIG. 3, FIG. 7, and FIG.

In step 2, it is checked whether the purge condition is satisfied. If it is not the purge condition, the process proceeds to step 3 and the purge cut valve 29 is closed.

Purge conditions are as follows: <1> Low load after engine warm-up is complete <2> Air-fuel ratio feedback correction and cooling water temperature 60
It is either case when the water temperature is below ℃. <1> is the same as the conventional one.
Unlike the conventional method, <2> is added in order to improve the combustion state by introducing a highly volatile purge gas under this condition.

Under the purging conditions, the fuel concentration A (described later in FIG. 7) A in the purge gas is read from the memory in step 4, and the basic purge valve opening is read from this fuel concentration A by referring to the table having the content of FIG. Calculate PV0. As shown in FIG. 4, the reason why the characteristic of the basic purge valve opening PV0 is made substantially inversely proportional is that the fuel flow rate passing through the purge valve 27 is made substantially constant even if the fuel concentration in the purge gas is different. .

In steps 5 and 6, the cooling water temperature Tw is used as shown in FIG.
The opening correction rate Kpv is obtained by referring to the table having the contents of the table, and the purge valve opening PV is calculated by the equation PV = PV0 × Kpv (4) in order to increase and correct the basic purge valve opening PV0.

As shown in FIG. 5, the opening degree correction rate Kpv is 100% or more at approximately 60 ° C. or less. 60 ° C
The reason why the purge valve opening amount is increased and corrected at the low water temperature below is to supply a large amount of highly volatile purge gas at the low water temperature immediately after starting when the activity of the catalyst 6 becomes insufficient.
This is to improve the combustion state.

In steps 7 and 8, the purge valve opening PV
6 to the table having the contents of FIG. 6, the number of steps STE given to the step motor for driving the purge valve
P is calculated and output to the output register,
In step 9, the purge cut valve 29 is opened.

Since the above-mentioned purge valve opening PV is necessary in FIG. 7, the purge valve opening P is determined in step 10.
Store V in memory.

In FIG. 7, it is checked whether purging is being performed in steps 11 and 12 and whether air-fuel ratio feedback correction is being performed. If purging is being performed and air-fuel ratio feedback correction is being performed, the process proceeds to step 13 and thereafter. Calculate the fuel concentration inside.

The conditions for stopping the air-fuel ratio feedback correction are at the time of starting, at the time of high load, when the O ₂ sensor is abnormal, and the like, and the conditions other than these conditions are the air-fuel ratio feedback conditions. The fuel concentration in the purge gas is estimated under the condition that the air-fuel ratio feedback correction is being performed, because the air-fuel ratio feedback correction coefficient α changes under this condition (when the fuel concentration in the purge gas is richer than the stoichiometric air-fuel mixture). Changes to the side where α becomes smaller than 100%, and conversely changes to the side where α becomes larger than 100% when the mixture is thinner than the stoichiometric air-fuel ratio), and the amount of change in α corresponds to the purge gas fuel concentration. Because it does.

Therefore, in step 13, the difference Δα [%] between the air-fuel ratio feedback correction coefficient α [%] during purging and the average value of α during non-purging (≈100%) is Δα = α-100 ... ( It is calculated by the formula of 5). The value of Δα becomes Δα <0 when the purge gas is richer than the stoichiometric air-fuel mixture, and Δα when the purge gas is thinner than the stoichiometric air-fuel mixture.
> 0.

When a wide range air-fuel ratio sensor is used instead of the O ₂ sensor, it is possible to estimate the fuel concentration in the purge gas even if the air-fuel ratio feedback correction is not being performed.

In steps 14 and 15, referring to the table having the contents shown in FIG. 8 from the purge valve opening PV stored in the memory, the air flow rate Q _EVAP [kg / kg] in the purge gas.
h] is obtained, and using the air flow rate Q _EVAP in the purge gas, the above difference Δα, and the intake air flow rate Qa [kg / h], the fuel concentration A [unknown number] in the purge gas is A = (1/14. 7) × (1- (Qa / Q _EVAP ) × Δα / 100) (6)

In step 16, the fuel concentration A and the air flow rate Q _EVAP in the purge gas are stored in the memory.

The above equation (6) can be derived as follows. The fuel concentration A in the purge gas _{A≡G EVAP / Q EVAP ... (7} ) however, G _EVAP; fuel flow rate Q _EVAP in the purge gas; when defined in formula of the air flow in the purge gas, also in the air-fuel ratio feedback correction exhaust Since control is performed so that the air-fuel ratio matches the theoretical air-fuel ratio (assumed to be 14.7), the fuel flow rate during purge and the air flow rate during purge are (fuel flow rate during purge) / (purge rate) The air flow rate inside) = 1 / 14.7 (8) must be satisfied.

Here, the fuel flow rate during purging and the air flow rate during purging are the fuel flow rate during purging = the fuel flow rate in the purge gas + the fuel flow rate from the injector = Q _EVAP x A + Qa x (1 / 14.7) x (Δα + 100) / 100 (9) Air flow rate during purging = Air flow rate in purge gas + Air flow meter passing air flow rate = Q _EVAP + Qa (10) _Therefore , if these are substituted into the equation (8), {Q _EVAP × A + Qa × (1 / 14.7) × (Δα + 100) / 100} / (Q _EVAP + Qa) = 1 / 14.7 (11)

When the equation (11) is arranged for the fuel concentration A, A = (1 / 14.7) × {1 + Qa / Q _EVAP− (Qa / Q _EVAP ) × (Δα + 100) / 100} = (1/14. 7) × (1− (Qa / Q _EVAP ) × Δα / 100), and the above equation (6) is obtained.

In FIG. 9, in steps 21 and 22, the basic injection pulse width (engine load equivalent amount) Tp is read, and the basic ignition timing ADV0 is obtained from this and the engine speed Ne by referring to the map having the content of FIG. . The basic ignition timing ADV0 is a value matched during non-purging and is the same as the conventional one.

In steps 23, 24 and 25, the following conditions <3> purging is in progress, <4> air-fuel ratio feedback correction is in progress, <5> cooling water temperature Tw is at a low temperature of 60 ° C. or less. If either condition is not satisfied, the routine proceeds to steps 26 and 27, where the basic ignition timing ADV0 is directly input to the variable ADV representing the ignition timing to be given to the power transistor, and this is stored in the output register. Forward.

When all the above three conditions <3> to <5> are satisfied, the process proceeds to steps 28 to 32.

In steps 28 and 29, the intake air flow rate Q
a and the air-fuel ratio feedback correction coefficient α during the purge, the fuel flow rate Ginj from the injector 4 is expressed by the following equation: Ginj = Qa × (1 / 14.7) × α (12), and the air flow rate Q in the purge gas is Q. _{Using EVAP} and fuel concentration A, the fuel flow rate G _EVAP in the purge gas is calculated by the equation G _EVAP = Q _EVAP × A (13), and in step 30, the fuel ratio R of the purge gas is R.
The calculating formula of _{R EVAP = G EVAP / (Ginj} + G EVAP) ... (14) EVAP.

In steps 31 and 32, this fuel ratio R
_The retard correction amount ΔADV is obtained from EVAP by referring to the table having the contents shown in FIG. 11, and the value obtained by subtracting the retard correction amount ΔADV from the basic ignition timing ADV0 is put into the variable ADV. Since the ignition timing represents the value before the compression top dead center, the basic ignition timing A
The ignition advance value can be retarded by subtracting the correction amount ΔADV from DV0.

The operation of this example will now be described. Gasoline as a fuel is a mixture of a very large number of hydrocarbon molecules, but since the components adsorbed on the canister 23 are volatile components such as methane and ethane having a small carbon number, the purge gas is highly volatile. When the gaseous purge gas is mixed into the intake pipe 2 in addition to the liquid fuel from the injector 4, the combustion characteristics in the combustion chamber are improved, so that when the air-fuel ratio is constant as shown in FIG. (When the exhaust air-fuel ratio is maintained at the stoichiometric air-fuel ratio (shown as stoichiometric in the figure) by air-fuel ratio feedback correction), the surge limit expands in the retard direction of the ignition timing as the fuel flow rate in the purge gas increases (fuel concentration increases) To do. That is, while the purge gas is being introduced, even if the ignition timing is retarded as compared with the non-purging time, a surge does not occur and the drivability is not deteriorated.

Utilizing this characteristic, in this example, the purge gas is introduced into the intake pipe during the feedback correction of the air-fuel ratio and at the low water temperature such as 25 to 60 ° C., and the ignition timing is retarded compared to the non-purging time. While maintaining good operability, the exhaust gas temperature rises by the amount by which the ignition timing is retarded compared to the non-purge time, and activation of the catalyst can be promoted (exhaust performance can be improved).

Further, the fuel concentration A in the purge gas is calculated based on the air-fuel ratio feedback correction coefficient α and the purge valve opening A during purging and air-fuel ratio feedback correction, and during purging and air-fuel ratio feedback correction 60
The fuel ratio R _EVAP of the purge gas is _calculated based on the fuel concentration A in the purge gas and the air-fuel ratio feedback correction coefficient α at a low water temperature of ℃ or less, and the fuel ratio R of this purge gas is R.
_Since the retard correction amount ΔADV of the ignition timing is increased as EVAP increases, the retard correction amount ΔADV can be provided without excess or deficiency even if the fuel concentration A in the purge gas is different. As shown in FIG. 13, the exhaust gas temperature can be raised according to the purge gas fuel ratio R _EVAP .

Further, at the time of low water temperature immediately after the start when the activity of the catalyst 6 becomes insufficient, the purge valve opening amount is increased and corrected, and a large amount of purge gas having high volatility is supplied, whereby the ignition timing retard correction amount ΔADV. Can be further increased, and thus warming up of the catalyst can be further promoted.

On the other hand, in order to improve the operability, the air-fuel ratio feedback correction is stopped from immediately after the cold start, and the fuel amount is increased to supply the air-fuel mixture richer than the stoichiometric air-fuel ratio. By introducing a highly volatile purge gas to improve combustion even from the time of startup to immediately afterward, the operability is further improved and the HC at the catalyst inlet can be reduced, and the amount of fuel is reduced by the amount of introduced purge gas. By doing so, fuel economy is also improved. However,
Since the O ₂ sensor does not output normally from the cold start when the air-fuel ratio feedback correction is stopped to immediately after that, when introducing the purge gas from the cold start to immediately after that, instead of the O ₂ sensor, It goes without saying that the fuel ratio of the purge gas must be calculated using the wide range air-fuel ratio sensor.

Next, in order to improve fuel economy, the target air-fuel ratio is set to a value leaner than the stoichiometric air-fuel ratio under lean conditions, and the engine is operated with this lean side target air-fuel ratio.
In the driving range (non-lean condition) where the output is insufficient,
In a lean burn engine that uses the stoichiometric air-fuel ratio as the target air-fuel ratio to perform feedback correction of the air-fuel ratio, by introducing purge gas under lean conditions, the target air-fuel ratio can be made leaner by the amount of combustion improvement, This further improves fuel efficiency. On the other hand, as shown in FIG. 12 described above, the expansion of the surge region due to the highly volatile purge gas also occurs with respect to the air-fuel ratio, and even if the ignition timing is the same, the surge region expands to the lean side during purging, so the target during purging By correcting the air-fuel ratio to the lean side, surge does not occur.

This is realized by the flow charts of FIGS. 14 and 15 of the second embodiment. The flow chart of FIG. 14 showing the calculation of the fuel concentration in the purge gas is shown in FIG. 7 of the previous embodiment and by the injector. The flow chart of FIG. 15 showing the calculation of the fuel injection pulse width Ti given to No. 4 corresponds to FIG.

First, the purge condition in this example is different from that of the previous embodiment. <6> At the time of low load after completion of warm-up of the engine during air-fuel ratio feedback correction <7> Lean condition is there.

In this example, as will be described later, the fuel concentration A is calculated and stored during the purge in the case of <6>, the non-lean condition and the air-fuel ratio feedback correction, and <7>. In this case, the fuel concentration A is read and used under the lean condition during purging. The reason for calculating the fuel concentration in the case of <6> is that the difference Δα cannot be calculated unless the air-fuel ratio feedback correction is being performed because the O ₂ sensor is used.

In FIG. 14, steps 41, 42, 4
In 3, the following conditions <8> purging, <9> non-lean condition, <10> air-fuel ratio feedback correction in progress are checked. Then, the fuel concentration A in the purge gas is calculated as in the previous embodiment, and the fuel concentration A and the air flow rate Q _EVAP in the purge gas are stored in the memory.

In FIG. 15, in steps 52 and 53, it is checked whether or not purging is in progress and whether or not lean conditions are satisfied. The lean condition is, for example, a cooling water temperature Tw of 80 ° C.
That is, all the conditions that the throttle valve opening from the throttle sensor is less than or equal to a predetermined value and that the vehicle speed change is less than or equal to a predetermined value are satisfied.

If purging and lean conditions are set, in step 54, the target fuel-air ratio map value Tfbya0 under lean conditions is referenced from the engine speed Ne and the basic injection pulse width Tp with reference to the lean map having the contents of FIG. Ask.

When the value of the target fuel-air ratio map value Tfbya0 is 1.0, it corresponds to the theoretical air-fuel ratio, and as shown in FIG. 16, when it is smaller than 1.0, it becomes the lean-side air-fuel ratio. . In addition, fuel control is performed aiming at the target air-fuel ratio,
Considering that the supplied fuel amount is finally obtained from the detected value of the air flow rate, the relationship of air flow rate × fuel-air ratio = supplied fuel amount holds, so the fuel-air ratio is easier to handle than the air-fuel ratio. , The fuel-air ratio is used.

[0079] At step 55, 56, 57, as in the previous embodiment calculates the fuel ratio R _EVAP purge gas,
In step 58 and 59 from the fuel ratio R _EVAP by referring to the table for 17 contents fuel-air ratio correction amount ΔTfby
a, and a value obtained by multiplying the target fuel-air ratio map value Tfbya0 by the correction amount ΔTfbya is used as the target fuel-air ratio Tfby.
a.

As shown in FIG. 17, the correction amount ΔTfby
a is a value of 100% or less, and is corrected to the side that reduces the target fuel-air ratio by multiplying the map value Tfbya0 by the correction amount ΔTfbya (correction of the target air-fuel ratio to the lean side).
It does.

In steps 60 and 61, the fuel injection pulse width Ti given to the injector is calculated by the equation Ti = Tp × Tfbya + Ts (21) and this value is transferred to the output register.

The basic injection pulse width Tp and the invalid pulse width Ts in the equation (21) have the same values as in the previous embodiment.

In this way, by introducing the purge gas under the lean condition and correcting the target air-fuel ratio under the lean condition to the lean side, it is possible to further improve the fuel consumption without causing a surge.

Further, during the air-fuel ratio feedback correction, the fuel concentration A in the purge gas during purging under a low load (second purge condition) after completion of warming up of the engine (second purge condition) and during the air-fuel ratio feedback correction is controlled. Calculated and stored, and during the purging under the lean condition (first purge condition) and under the lean condition, from the fuel concentration A to the purge gas fuel ratio R
The _EVAP, since seeking further fuel-air ratio correction amount DerutaTfbya from the purge gas fuel ratio R _EVAP, also fuel concentration A in the purge gas is different, it is possible to provide just enough fuel-air ratio correction amount DerutaTfbya. As a result, as shown in FIG. 18, the fuel consumption can be improved according to the purge gas fuel ratio R _EVAP .

FIG. 19 shows NOx which is a harmful component in exhaust gas.
This is a so-called EGR device in which an inert exhaust gas is recirculated to the intake pipe in order to suppress the generation of. This device
EGR passage 10 that connects the intake pipe 101 and the exhaust pipe 102
3. EGR for adjusting the gas flow rate in this passage 103
The valve 104 and the EGR valve 104 are composed of a negative pressure control valve 105 for adjusting a control negative pressure.

The negative pressure control valve 105 guides the intake pipe negative pressure downstream of the intake throttle valve through the passage 105c to generate a constant negative pressure and a constant pressure valve 105a to introduce the atmosphere into the negative pressure. And a solenoid valve 105b that creates a control negative pressure to the EGR valve 104, and the EGR valve flow rate is OFF to the solenoid valve 105b.
The OFF duty is adopted as a control value for the solenoid valve 105b, because it is determined almost in proportion to the duty (closed valve closing time ratio of a constant cycle) (the EGR flow rate increases as the OFF duty increases).

In this EGR device, the EGR is performed under the EGR condition.
The maximum temperature during combustion is lowered by opening a valve and mixing a certain amount of exhaust gas (EGR gas) into the intake air. The target value of the EGR rate (ratio between EGR gas amount and fresh air amount) is the engine. However, the control unit 11 controls the target EGR according to the operating conditions.
The OFF duty to the solenoid valve 105b is controlled so that it becomes the ratio.

The third embodiment is an example of application of the present invention to such EGR control. When the purge gas is introduced into the EGR, the combustion state is improved.
The R rate can be increased, and the combustion temperature can be lowered correspondingly, and the NOx emission amount can be reduced.

The purging conditions of this example are as follows: <11> During low load after engine warm-up is complete <12> During EGR and air-fuel ratio feedback correction, during purging during <12> and E
The fuel concentration A in the purge gas is calculated during the GR and during the air-fuel ratio feedback correction, and the EGR valve opening degree is corrected using this fuel concentration A.

The flow charts of FIGS. 20 and 21 correspond to the combination of FIGS. 7 and 9 of the first embodiment.

20 and 21, it is checked in step 71 whether the EGR condition is satisfied. Conditions for cutting the EGR are as follows: engine start, idling, deceleration, and cooling water temperature within a predetermined range (for example, 60 ° C. or higher and 10 ° C. or higher).
0 ° C or less), the operating conditions other than these are EG
R condition.

When the EGR condition is met, the routine proceeds to step 72, where the basic injection pulse width Tp and the engine speed Ne are shown in FIG.
The basic EGR valve opening degree V _EGR 0 is obtained by referring to the map having the contents of 2.

At steps 73 and 74, it is determined whether the air-fuel ratio feedback correction is being performed or is being purged. If the purge is being performed and the air-fuel ratio feedback is being corrected, the process proceeds to steps 75 to 80 in FIG. Similarly to the above, the fuel ratio R _{EVAP of the} purge gas is obtained.

In steps 81 and 82 of FIG. 20, the opening correction amount ΔV _EGR is obtained from the fuel ratio R _EVAP by referring to the table having the contents shown in FIG. 23, and this correction amount ΔV _EGR is used as the basic EGR valve opening V. _The value added to _EGR 0 is determined as the EGR valve opening V _EGR .

In FIG. 23, the reason why the opening correction amount ΔV _EGR is made small in the region where the fuel ratio R _EVAP is small is to set the dead zone by setting the gradient of the characteristic in two stages.
The opening correction amount ΔV _EGR is not increased unless the fuel ratio R _EVAP is increased to some extent.

At steps 83 and 84, the EGR valve opening degree V _EGR is converted into the OFF duty D _OFF to the solenoid valve 105b by referring to the table having the contents shown in FIG. 24, and this is transferred to the output register.

As described above, in this example, the purge gas is introduced under the EGR condition and the air-fuel ratio feedback correction condition as the purge condition, and the EGR valve opening amount is increased during the purging condition, the EGR condition condition and the air-fuel ratio feedback correction condition. The EGR rate can be increased by an amount corresponding to the improvement of the combustion state due to the introduction of the purge gas, which lowers the combustion temperature and reduces the NOx emission amount.

Further, the air-fuel ratio feedback correction coefficient α during purging, EGR, and air-fuel ratio feedback correction
And the purge valve opening PV and the fuel concentration A in the purge gas, and further the fuel ratio R _{EVAP of the} purge gas is _calculated based on the fuel concentration A and the air-fuel ratio feedback correction coefficient α, and according to the fuel ratio R _EVAP. Since the opening correction amount ΔV _EGR is obtained and the basic EGR valve opening V _EGR 0 is corrected by this, the opening correction amount ΔV _EGR can be given without excess or deficiency even if the fuel concentration A in the purge gas differs.

In the third embodiment, the EGR valve opening is used as the controlled variable, but the EGR rate may be used as the controlled variable.

[0100]

According to the first aspect of the present invention, the means for calculating the basic ignition timing according to the operating condition signal, the sensor for detecting the oxygen concentration in the exhaust gas, the means for heating the sensor, and the heating means are used. And means for activating the sensor early at the time of starting, and means for performing feedback correction of the air-fuel ratio based on the sensor output so that the air-fuel ratio matches the theoretical air-fuel ratio from the low water temperature before the completion of warming up of the catalyst. , A purge valve that opens and closes a passage that introduces the fuel adsorbed in the canister into the intake pipe together with fresh air according to a drive signal, and a purge condition is when the air-fuel ratio feedback correction is being performed and the temperature of the water is low before completion of warming of the catalyst. Means for determining whether or not the purge condition is satisfied, means for opening the purge valve under the purge condition based on the determination result, and completion of warm-up of the catalyst during purging Means for determining whether the low water temperature is low, and means for calculating the ignition timing by retarding the basic ignition timing at the low water temperature during purging and before completion of warming up of the catalyst from this determination result, Since a means for outputting an ignition signal to the ignition device is provided so that the sparks fly at this ignition timing, the exhaust performance is improved by the amount by which the exhaust temperature rises with the ignition timing retard correction without causing a surge. Can be improved.

A second aspect of the invention is to use a means for calculating the basic ignition timing according to the operating condition signal, a sensor for detecting the oxygen concentration in the exhaust gas, a means for heating this sensor, and a starting means using this heating means. Sometimes means for activating the sensor early, means for calculating the air-fuel ratio feedback correction coefficient so that the air-fuel ratio matches the theoretical air-fuel ratio from the low water temperature before the warming-up of the catalyst based on the sensor output, A means for calculating the fuel injection amount by correcting the basic injection amount according to the operating condition signal with this feedback correction coefficient, a device for supplying this injection amount of fuel to the intake pipe, and a fuel for adsorbing fuel on the canister. A purge valve that adjusts the flow rate of the passage introduced into the intake pipe in accordance with a drive signal, and a purge condition at the time of low water temperature during the air-fuel ratio feedback correction and before the completion of warming up of the catalyst Means for determining whether or not the purge condition is satisfied, a means for calculating the purge valve opening degree from the fuel concentration in the purge gas under the purge condition based on the determination result, and a drive signal corresponding to the purge valve opening degree for the purge valve. And a means for determining whether the air-fuel ratio feedback correction is being performed, and the air-fuel ratio feedback correction coefficient and the purge valve during purging and during the air-fuel ratio feedback correction. A means for calculating the fuel concentration in the purge gas based on the opening degree; a means for determining whether or not during the purge and during the air-fuel ratio feedback correction and at a low water temperature before the completion of warming up of the catalyst, Based on this determination result, the purge is being performed, the air-fuel ratio feedback correction is being performed, and A means for calculating the fuel ratio of the purge gas based on the fuel concentration in the purge gas and the air-fuel ratio feedback correction coefficient at the time of water temperature; and a means for calculating a retard correction amount that increases according to the fuel ratio of the purge gas. Since the means 72 for calculating the ignition timing by correcting the basic ignition timing with the retard correction amount and the means for outputting the ignition signal to the ignition device so that the sparks fly at the ignition timing are provided, First
In addition to the effect of the invention described above, even if the fuel concentration in the purge gas is different, the retard correction amount can be provided without excess or deficiency.

In the third aspect of the invention, in the second aspect of the invention, the purge valve opening degree is increased and corrected at a low water temperature before the completion of warming up of the catalyst. Therefore, in addition to the effect of the second aspect of the invention, the catalyst warm-up is further enhanced. Can be promoted.

A fourth aspect of the present invention provides a means for calculating the basic value of the lean side target air-fuel ratio in a lean condition according to an operating condition signal, and a passage for introducing the fuel adsorbed in the canister together with fresh air into the intake pipe. A purge valve that opens and closes according to a drive signal, a means for determining whether or not this lean condition is the lean condition as the purge condition, a means for opening the purge valve under the purge condition based on the result of this determination, a purge condition and a lean condition. Means for determining whether the condition is satisfied, means for calculating the target air-fuel ratio by correcting the basic value of the target air-fuel ratio to the lean side under purging and the lean condition from the result of this determination, and the target air-fuel ratio A means for calculating the fuel injection amount under the lean condition by correcting the basic injection amount according to the operating condition signal and a device for supplying the fuel of this injection amount to the intake pipe are provided. Because, without causing a surge, it is possible to improve the amount corresponding fuel economy improving combustion by the introduction of purge gas.

A fifth aspect of the present invention is based on a sensor for detecting the oxygen concentration in the exhaust gas, and based on the sensor output, the air-fuel ratio feedback control is performed so that the exhaust air-fuel ratio matches the theoretical air-fuel ratio under the non-lean condition and the air-fuel ratio feedback condition. A means for calculating the correction coefficient, a purge valve that adjusts the flow rate of the passage that introduces the fuel adsorbed in the canister with the fresh air into the intake pipe, and the basic value of the lean side target air-fuel ratio under lean conditions. The lean condition is the first purge condition, and the lean condition after the engine is warmed up during the air-fuel ratio feedback correction is the second purge condition. Means for determining whether or not, and a means for calculating the opening of the purge valve from the fuel concentration in the purge gas under the purge condition based on the determination result, A means for outputting a drive signal according to the opening degree of the purge valve to the purge valve, and means for determining whether the purge is being performed under the second purge condition, the non-lean condition and the air-fuel ratio feedback correction are being performed. From the determination result, the fuel concentration in the purge gas is calculated based on the air-fuel ratio feedback correction coefficient and the purge valve opening during purging under the second purge condition, the non-lean condition, and during the air-fuel ratio feedback correction. Means for determining whether the purge is under the first purge condition and the lean condition, and based on the determination result, whether the purge gas is under the purge condition under the first purge condition and the purge gas under the lean condition. Means for calculating the fuel ratio of the purge gas based on the fuel concentration and the basic value of the target air-fuel ratio, and the purge gas Means for calculating an air-fuel ratio correction amount that becomes smaller as the fuel ratio increases, and means for calculating a target air-fuel ratio by correcting the basic value of the target air-fuel ratio to the lean side with this air-fuel ratio correction amount, During purging under the first purge condition and the lean condition, the target air-fuel ratio is corrected under this target air-fuel ratio, and under the non-lean condition and the air-fuel ratio feedback condition under the air-fuel ratio feedback correction coefficient, the basic injection amount is corrected in accordance with the operating condition signal. Since the means for calculating the fuel injection amount and the device for supplying this injection amount of fuel to the intake pipe are provided, in addition to the effect of the fourth invention, even if the fuel concentration in the purge gas differs, The fuel ratio correction amount can be given without excess or deficiency.

A sixth aspect of the present invention is an EGR valve whose opening changes according to a drive signal, a means for calculating a basic EGR valve opening according to an operating condition signal under EGR conditions, and a fuel adsorbed in a canister. And a purge valve that opens and closes the passage that introduces the air into the intake pipe with fresh air,
Means for determining whether or not the purge condition is the EGR state as the purge condition, means for opening the purge valve under the purge condition based on the determination result, and means for determining whether the purge is being performed and the EGR is being performed. From this determination result, the basic EGR during purging and during the EGR is performed.
A means for calculating the EGR valve opening by increasing and correcting the valve opening, and a signal corresponding to the EGR valve opening
Since the means for outputting to the R valve is provided, the EGR rate is increased by the amount of the improvement in combustion due to the introduction of the purge gas, so the combustion temperature is lowered, and thereby the NOx emission amount can be reduced.

In a seventh aspect of the invention, means for calculating the basic EGR valve opening degree according to the operating condition signal under EGR conditions, a sensor for detecting the oxygen concentration in the exhaust gas, and the exhaust air-fuel ratio based on the sensor output are used. Means for calculating the air-fuel ratio feedback correction coefficient so as to match the theoretical air-fuel ratio, means for calculating the fuel injection amount by correcting the basic injection amount according to the operating condition signal with this feedback correction coefficient, and this injection amount A device for supplying fuel to the intake pipe, a purge valve for adjusting a flow rate of a passage for introducing the fuel adsorbed in the canister together with fresh air into the intake pipe, and the EGR.
Means for determining whether or not the purge condition is the middle and the air-fuel ratio feedback correction is being performed,
Based on this determination result, means for calculating the purge valve opening from the fuel concentration in the purge gas under the purge condition, means for outputting a drive signal corresponding to the purge valve opening to the purge valve, during purging and during the air-fuel ratio feedback correction And means for determining whether or not the EGR is being performed, and based on the result of the determination, during the purge, during the air-fuel ratio feedback correction, and during the EGR, during the purge gas based on the air-fuel ratio feedback correction coefficient and the purge valve opening degree. Means for calculating the fuel concentration of the EG, and during the purging, the air-fuel ratio feedback correction, and the EG
Means for calculating the fuel ratio of the purge gas based on the fuel concentration in the purge gas and the air-fuel ratio feedback correction coefficient during R, and means for calculating the opening correction amount that increases according to the fuel ratio of the purge gas. And means for calculating the EGR valve opening by increasing and correcting the basic EGR valve opening with this opening correction amount, and E
Since means for outputting a signal according to the GR valve opening to the EGR valve is provided, in addition to the effect of the sixth invention,
Even if the fuel concentration in the purge gas is different, it is possible to give the opening correction amount without excess or deficiency.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the first invention.

FIG. 2 is a control system diagram of an embodiment.

FIG. 3 is a flow chart for explaining control of a purge valve and a purge cut valve.

FIG. 4 is a characteristic diagram of a basic purge valve opening PV0.

FIG. 5 is a characteristic diagram of an opening correction rate Kpv.

FIG. 6 shows the number of steps ST with respect to the purge valve opening PV
It is a characteristic view of EP.

FIG. 7 is a flow chart for explaining calculation of a fuel concentration A.

FIG. 8 is a characteristic diagram of an air flow rate Q _{EVAP in} purge gas with respect to a purge valve opening PV.

FIG. 9 is a flow chart for explaining calculation of ignition timing ADV.

FIG. 10 is a characteristic diagram of a basic ignition timing ADV0.

FIG. 11 is a characteristic diagram of a retard correction amount ΔADV.

FIG. 12 is a characteristic diagram showing surge limits during purging and non-purging.

FIG. 13 is a characteristic diagram of an ignition timing ADV and an exhaust temperature with respect to a purge gas fuel ratio R _EVAP .

FIG. 14 is a flowchart for explaining calculation of a fuel concentration A of the second embodiment.

FIG. 15 is a flowchart for explaining calculation of a fuel injection pulse width Ti in the second embodiment.

FIG. 16 is a characteristic diagram of a target fuel-air ratio map value Tfbya0.

FIG. 17 is a characteristic diagram of a fuel-air ratio correction amount ΔTfbya.

[18] target air-fuel ratio Tfbya for purge fuel ratio R _EVAP of the second embodiment, the air-fuel ratio, which are the characteristic diagram of fuel efficiency cost.

FIG. 19 is a flowchart for explaining calculation of a target fuel-air ratio Tfbya.

[18] target air-fuel for the purge fuel ratio R _EVAP ratio Tfbya _EVAP, the air-fuel ratio, which are the characteristic diagram of fuel efficiency cost.

FIG. 19 is a control system diagram of an EGR control device according to a third embodiment.

FIG. 20: OF to the solenoid valve 105b of the third embodiment
6 is a flowchart for explaining calculation of F duty D _OFF .

FIG. 21: OF to the solenoid valve 105b of the third embodiment
6 is a flowchart for explaining calculation of F duty D _OFF .

FIG. 22 is a characteristic diagram of a basic EGR valve opening degree V _EGR .

FIG. 23 is a characteristic diagram of an opening correction amount ΔV _EGR .

FIG. 24 is a characteristic diagram of the OFF duty D _OFF with respect to the EGR valve opening degree V _EGR .

FIG. 25 is a diagram corresponding to the claim of the second invention.

FIG. 26 is a diagram corresponding to the claim of the fourth invention.

FIG. 27 is a diagram corresponding to the claim of the fifth invention.

FIG. 28 is a diagram corresponding to the claim of the sixth invention.

FIG. 29 is a diagram corresponding to the claim of the seventh invention.

[Explanation of symbols]

4 injector (fuel supply device) 6 catalyst 7 O ₂ sensor (oxygen concentration sensor) 8 power transistor 11 control unit 12 crank angle sensor 13 air flow meter 14 water temperature sensor 23 canister 27 purge valve 41 basic ignition timing calculation means 42 oxygen concentration sensor 43 heating Means 44 Early activation means 45 Air-fuel ratio feedback correction means 46 Purge valve 47 Purge condition judgment means 48 Valve opening means 49 Judgment means 50 Ignition timing calculation means 51 Ignition signal output means 52 Ignition device 61 Air-fuel ratio feedback correction coefficient calculation means 62 Fuel injection Quantity calculation means 63 Fuel supply device 64 Purge valve 65 Purge valve opening calculation means 66 Valve opening signal output means 67 Judgment means 68 Fuel concentration calculation means 69 Judgment means 70 Fuel allocation Calculation means 71 Delay angle correction amount calculation means 72 Ignition timing calculation means 81 Basic value calculation means 82 Purge condition determination means 83 Determination means 84 Target air-fuel ratio calculation means 85 Fuel injection amount calculation means 91 Air-fuel ratio feedback correction coefficient calculation means 92 Purge conditions Judgment means 93 Judgment means 94 Fuel concentration calculation means 95 Judgment means 96 Fuel ratio calculation means 97 Air-fuel ratio correction amount calculation means 98 Target air-fuel ratio calculation means 99 Fuel injection amount calculation means 104 EGR valve 105b Solenoid valve 111 EGR valve 112 Basic EGR valve Opening degree calculation means 113 Purging condition determination means 114 Determination means 115 EGR valve opening degree calculation means 116 Valve opening degree signal output means 121 Purge condition determination means 122 Determination means 123 Fuel concentration calculation means 124 Fuel ratio calculation means 125 Opening correction amount calculation Means 126 EGR valve opening calculation means

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[Procedure amendment]

[Submission date] June 7, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a diagram corresponding to a claim of the first invention.

FIG. 2 is a control system diagram of an embodiment.

FIG. 3 is a flow chart for explaining control of a purge valve and a purge cut valve.

FIG. 4 is a characteristic diagram of a basic purge valve opening PV0.

FIG. 5 is a characteristic diagram of an opening correction rate Kpv.

FIG. 6 shows the number of steps ST with respect to the purge valve opening PV
It is a characteristic view of EP.

FIG. 7 is a flow chart for explaining calculation of a fuel concentration A.

FIG. 8 is a characteristic diagram of an air flow rate Q _{EVAP in} purge gas with respect to a purge valve opening PV.

FIG. 9 is a flow chart for explaining calculation of ignition timing ADV.

FIG. 10 is a characteristic diagram of a basic ignition timing ADV0.

FIG. 11 is a characteristic diagram of a retard correction amount ΔADV.

FIG. 12 is a characteristic diagram showing surge limits during purging and non-purging.

FIG. 13 is a characteristic diagram of an ignition timing ADV and an exhaust temperature with respect to a purge gas fuel ratio R _EVAP .

FIG. 14 is a flowchart for explaining calculation of a fuel concentration A of the second embodiment.

FIG. 15 is a flowchart for explaining calculation of a fuel injection pulse width Ti in the second embodiment.

FIG. 16 is a characteristic diagram of a target fuel-air ratio map value Tfbya0.

FIG. 17 is a characteristic diagram of a fuel-air ratio correction amount ΔTfbya.

[18] target air-fuel for the purge fuel ratio R _EVAP ratio Tfbya _EVAP, the air-fuel ratio, which are the characteristic diagram of fuel efficiency cost.

FIG. 19 is a control system diagram of an EGR control device according to a third embodiment.

FIG. 20: OF to the solenoid valve 105b of the third embodiment
6 is a flowchart for explaining calculation of F duty D _OFF .

FIG. 21: OF to the solenoid valve 105b of the third embodiment
6 is a flowchart for explaining calculation of F duty D _OFF .

FIG. 22 is a characteristic diagram of a basic EGR valve opening degree V _EGR .

FIG. 23 is a characteristic diagram of an opening correction amount ΔV _EGR .

FIG. 24 is a characteristic diagram of the OFF duty D _OFF with respect to the EGR valve opening degree V _EGR .

FIG. 25 is a diagram corresponding to the claim of the second invention.

FIG. 26 is a diagram corresponding to the claim of the fourth invention.

FIG. 27 is a diagram corresponding to the claim of the fifth invention.

FIG. 28 is a diagram corresponding to the claim of the sixth invention.

FIG. 29 is a diagram corresponding to the claim of the seventh invention.

[Explanation of symbols] 4 injector (fuel supply device) 6 catalyst 7 O ₂ sensor (oxygen concentration sensor) 8 power transistor 11 control unit 12 crank angle sensor 13 air flow meter 14 water temperature sensor 23 canister 27 purge valve 41 basic ignition timing calculation means 42 Oxygen concentration sensor 43 Heating means 44 Early activation means 45 Air-fuel ratio feedback correction means 46 Purge valve 47 Purge condition determination means 48 Valve opening means 49 Determination means 50 Ignition timing calculation means 51 Ignition signal output means 52 Ignition device 61 Air-fuel ratio feedback correction coefficient Calculation means 62 Fuel injection amount calculation means 63 Fuel supply device 64 Purge valve 65 Purge valve opening calculation means 66 Valve opening signal output means 67 Judgment means 68 Fuel concentration calculation means 69 Judgment hand Step 70 Fuel ratio calculation means 71 Delay angle correction amount calculation means 72 Ignition timing calculation means 81 Basic value calculation means 82 Purge condition determination means 83 Determination means 84 Target air-fuel ratio calculation means 85 Fuel injection amount calculation means 91 Air-fuel ratio feedback correction coefficient calculation Means 92 Purge condition judging means 93 Judging means 94 Fuel concentration calculating means 95 Judging means 96 Fuel ratio calculating means 97 Air-fuel ratio correction amount calculating means 98 Target air-fuel ratio calculating means 99 Fuel injection amount calculating means 104 EGR valve 105b Solenoid valve 111 EGR valve 112 Basic EGR Valve Opening Calculating Means 113 Purge Condition Determining Means 114 Determining Means 115 EGR Valve Opening Calculating Means 116 Valve Opening Signal Outputting Means 121 Purge Condition Determining Means 122 Determining Means 123 Fuel Concentration Calculating Means 124 Fuel Ratio Calculating Means 12 Opening correction amount calculating means 126 EGR valve opening calculation means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02D 41/14 P 43/00 301 B E M N F02M 25/07 550 R F02P 5/15

Claims (7)

[Claims] 1. A means for calculating a basic ignition timing according to an operating condition signal, a sensor for detecting an oxygen concentration in exhaust gas, a means for heating the sensor, and a heating means for using the sensor to start the sensor. A means for activating early, a means for performing feedback correction of the air-fuel ratio based on the sensor output so that the air-fuel ratio matches the stoichiometric air-fuel ratio from a low water temperature before the completion of warming up of the catalyst, and adsorbed on the canister. A purge valve that opens and closes a passage for introducing the fuel into the intake pipe together with fresh air according to a drive signal, and whether the purge condition is the low water temperature during the air-fuel ratio feedback correction and before the completion of warming up of the catalyst. A means for determining whether or not, and a means for opening the purge valve under purge conditions based on the determination result, and a low water temperature during purging and before completion of warming up of the catalyst A means for determining whether or not there is, a means for calculating the ignition timing by retarding the basic ignition timing at the time of low water temperature during purging and before completion of warming up of the catalyst from this determination result, and a spark at this ignition timing And a means for outputting an ignition signal to the ignition device so as to fly the fuel vapor processing apparatus for an engine. 2. A means for calculating a basic ignition timing according to an operating condition signal, a sensor for detecting an oxygen concentration in exhaust gas, a means for heating this sensor, and a heating means for controlling the sensor at the time of starting. Means for activating early, means for calculating an air-fuel ratio feedback correction coefficient based on the sensor output so that the air-fuel ratio matches the stoichiometric air-fuel ratio from a low water temperature before warming up of the catalyst, and this feedback correction coefficient Means for calculating the fuel injection amount by correcting the basic injection amount according to the operating condition signal, a device for supplying this injection amount of fuel to the intake pipe, and the fuel adsorbed in the canister to the intake pipe together with fresh air. A purge valve that adjusts the flow rate of the introduced passage according to the drive signal, and a low water temperature during the air-fuel ratio feedback correction and before the completion of warming up of the catalyst are set as purge conditions. Means for determining whether the purge condition is satisfied, means for calculating the purge valve opening from the fuel concentration in the purge gas under the purge condition based on the determination result, and a drive signal corresponding to the purge valve opening is output to the purge valve. Means for determining whether the purge is being performed and the air-fuel ratio feedback correction is being performed, and the determination result indicates that the air-fuel ratio feedback correction coefficient and the purge valve opening degree are being set during the purge and the air-fuel ratio feedback correction. Means for calculating the fuel concentration in the purge gas based on the above, and means for determining whether or not the purge is being performed, the air-fuel ratio feedback correction is being performed, and the low water temperature before completion of warming up of the catalyst, Low water temperature during purging and during air-fuel ratio feedback correction and before completion of warming up of the catalyst A means for calculating the fuel ratio of the purge gas based on the fuel concentration in the purge gas and the air-fuel ratio feedback correction coefficient, and a means for calculating a retard correction amount that increases as the fuel ratio of the purge gas increases. And a means for calculating the ignition timing by retarding the basic ignition timing with this retardation correction amount, and a means for outputting an ignition signal to the ignition device so that a spark will fly at this ignition timing. Evaporative fuel treatment device for engine. 3. The evaporated fuel processing apparatus for an engine according to claim 2, wherein the purge valve opening amount is increased and corrected at a low water temperature before the catalyst is warmed up. 4. A means for calculating a basic value of a target air-fuel ratio on the lean side in a lean condition according to an operating condition signal, and a passage for introducing fuel adsorbed in a canister with fresh air into an intake pipe in accordance with a drive signal. A purge valve that is opened and closed by the above, a means for determining whether or not this lean condition is the lean condition as the purge condition, a means for opening the purge valve under the purge condition based on the result of this determination, and whether or not the purge condition is under the lean condition. Means for determining whether or not, based on this determination result, means for calculating the target air-fuel ratio by correcting the basic value of the target air-fuel ratio to the lean side under the lean condition under the lean condition, and the operating condition signal at this target air-fuel ratio A means for calculating the fuel injection amount under the lean condition by correcting the corresponding basic injection amount and a device for supplying the fuel of this injection amount to the intake pipe are provided. Characteristic engine evaporated fuel processing device. 5. A sensor for detecting the oxygen concentration in the exhaust gas, and an air-fuel ratio feedback correction coefficient is calculated based on the sensor output so that the exhaust air-fuel ratio matches the theoretical air-fuel ratio under a non-lean condition and an air-fuel ratio feedback condition. Means, a purge valve that adjusts the flow rate of the passage that introduces the fuel adsorbed in the canister with the fresh air into the intake pipe, and the basic value of the lean side target air-fuel ratio under lean conditions as the operating condition signal. And the lean condition is a first purge condition, and a low load after completion of warm-up of the engine is being used as a second purge condition during air-fuel ratio feedback correction to determine whether these purge conditions are satisfied. Means for calculating the opening of the purge valve from the fuel concentration in the purge gas under the purge condition based on the determination result, and the purge valve Means for outputting a drive signal according to the opening to the purge valve; means for determining whether the purge is being performed under the second purge condition, the non-lean condition, and the air-fuel ratio feedback correction is being performed; From the result, means for calculating the fuel concentration in the purge gas based on the air-fuel ratio feedback correction coefficient and the purge valve opening during the purge under the second purge condition, the non-lean condition and the air-fuel ratio feedback correction And a means for determining whether the purge is under the first purge condition and is under the lean condition, and the fuel in the purge gas under the first purge condition and under the lean condition is determined from the result of the determination. Means for calculating the fuel ratio of the purge gas based on the concentration and the basic value of the target air-fuel ratio; The means for calculating an air-fuel ratio correction amount that decreases as the value increases, and means for calculating the target air-fuel ratio by correcting the basic value of the target air-fuel ratio to the lean side with this air-fuel ratio correction amount; During the purging under the purging condition and the lean condition, the basic injection amount is corrected according to the operating condition signal with the target air-fuel ratio and under the non-lean condition and the air-fuel ratio feedback condition with the air-fuel ratio feedback correction coefficient. An evaporated fuel processing apparatus for an engine, comprising: a unit for calculating a fuel injection amount; and a device for supplying the injection amount of fuel to an intake pipe. 6. An EG whose opening changes according to a drive signal.
An R valve, a means for calculating a basic EGR valve opening degree according to an operating condition signal under EGR conditions, and a purge valve for opening and closing a passage for introducing the fuel adsorbed in the canister with fresh air into the intake pipe according to the drive signal. , Means for determining whether or not this purge condition is the purge condition with the inside of the EGR, means for opening the purge valve under the purge condition based on the determination result, and means for determining whether the purge is being performed and the EGR is being performed And a means for calculating the EGR valve opening by increasing and correcting the basic EGR valve opening during purging and during the EGR based on this determination result, and outputting a signal corresponding to the EGR valve opening to the EGR valve. And an evaporative fuel treatment system for an engine. 7. A basic E according to an operating condition signal under an EGR condition.
Means for calculating the GR valve opening, a sensor for detecting the oxygen concentration in the exhaust gas, and means for calculating an air-fuel ratio feedback correction coefficient based on the sensor output so that the exhaust air-fuel ratio matches the theoretical air-fuel ratio, A means for calculating the fuel injection amount by correcting the basic injection amount according to the operating condition signal with this feedback correction coefficient, a device for supplying the fuel of this injection amount to the intake pipe, and a fuel for adsorbing fuel on the canister A purge valve that adjusts the flow rate of the passage introduced into the intake pipe in accordance with the drive signal, a means for determining whether or not this purge condition is the purge condition during the EGR and during the air-fuel ratio feedback correction, and the determination result Means for calculating the purge valve opening from the fuel concentration in the purge gas under the purge condition, and a drive according to the purge valve opening Signal to the purge valve, a means for determining whether the purge is being performed, the air-fuel ratio feedback correction is being performed, and the EGR is being performed, and a purge result, the air-fuel ratio feedback correction is being performed, and the EGR is being performed based on the determination result. Means for calculating the fuel concentration in the purge gas based on the air-fuel ratio feedback correction coefficient and the purge valve opening degree; and a fuel concentration in the purge gas during the purge, the air-fuel ratio feedback correction, and the EGR. Means for calculating the fuel ratio of the purge gas based on the air-fuel ratio feedback correction coefficient, means for calculating an opening correction amount that increases in accordance with the fuel ratio of the purge gas, and the basic opening correction amount A procedure for calculating the EGR valve opening by correcting the EGR valve opening by increasing the amount. If, evaporated fuel treatment device for an engine, characterized in that a means for outputting a signal corresponding to the EGR valve opening in the EGR valve.