JP3106823B2 - Evaporative fuel processor for engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In order to prevent fuel vaporized from a fuel tank from being released into the atmosphere, fuel vapor is adsorbed on an activated carbon canister, and this is purged into an intake pipe together with fresh air under predetermined operating conditions. There is one that burns in the inside (see JP-A-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; , The purge correction amount K is given in the second term on the right side of the equation for giving the fuel injection pulse width Ti given to the injector.
PG is introduced, and the amount of fuel injected from the injector is controlled so that the exhaust air-fuel ratio matches the stoichiometric air-fuel ratio even during the purge.

[0004] The purge correction amount KPG has a value other than 0 during feedback correction of the air-fuel ratio and during purge. If α is less than 1.0 and the output of the O ₂ sensor indicates a rich side when this condition is satisfied, the air-fuel ratio becomes rich by the amount of the purge gas (that is, the fuel concentration of the purge gas is high). ), And the purge correction amount KPG
Is increased by a predetermined value to decrease and correct the fuel injection pulse width of the first term. Conversely, when α exceeds the predetermined value and the O ₂ sensor output is on the lean side, the purge correction amount K
The fuel injection pulse width of the first term is increased by reducing PG by a predetermined amount.

[0005]

By the way, after the engine is started, it is better to enter the air-fuel ratio feedback correction as soon as possible, so that the exhaust performance is improved. Therefore, when the cooling water temperature Tw becomes a predetermined value (for example, 25 ° C. or less), the cooling water becomes empty. Fuel ratio feedback correction may be started.

[0006] This exhaust by instead of waiting for the O ₂ sensor is activated by being heated, but, made possible by to early activation of the O ₂ sensor at the same time a heater heating the starting.

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

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

On the other hand, there is a lean burn engine which sets the target air-fuel ratio to a value leaner than the stoichiometric air-fuel ratio under lean conditions in order to improve fuel efficiency, and operates at the lean-side target air-fuel ratio. Also 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 the improvement in combustion, thereby further improving the 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 increase.

However, in the above-described apparatus, there is no mention of low water temperature, lean burn engine, and EGR control during feedback correction of the air-fuel ratio.

Accordingly, an object of the present invention is to promote the warming-up of the catalyst and to improve the fuel efficiency and the exhaust performance by effectively utilizing the highly volatile purge gas.

[0012]

According to a first aspect of the present invention, as shown in FIG. 1, a basic ignition timing ADV according to an operation condition signal is provided.
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 sensor 42 is activated early by using the heating means 43 at the time of starting. Means for converting the air-fuel ratio to a stoichiometric air-fuel ratio from the time of low water temperature before the completion of warm-up of the catalyst based on the sensor output, and a fuel adsorbed to the canister. A purge valve 46 that opens and closes a passage for introducing air into the intake pipe together with fresh air in accordance with a drive signal, and whether the purge condition is a low water temperature during the air-fuel ratio feedback correction and before the completion of warm-up of the catalyst. Means 47 for determining whether or not the purge valve 46 is opened under purge conditions based on the result of the determination; Means 49 for judging whether or not the engine is at a low water temperature before the completion of the exhaust gas, and, based on the result of the judgment, the basic ignition timing ADV0 is retarded and the ignition timing ADV And a means 51 for outputting an ignition signal to an ignition device 52 such that a spark is emitted at the ignition timing ADV.

As shown in FIG. 25, the second invention comprises a means 41 for calculating a basic ignition timing ADV0 according to an operation condition signal, a sensor 42 for detecting an oxygen concentration in exhaust gas,
A means (for example, a heater) 4 for heating the sensor 42
3 and the sensor 4 at startup using this heating means 43.
Means 44 for activating the air-fuel ratio 2 at an early stage, and means 61 for calculating the air-fuel ratio feedback correction coefficient α such that the air-fuel ratio matches the stoichiometric air-fuel ratio from the time of low water temperature before the completion of the warm-up of the catalyst based on the sensor output. Means 62 for calculating the fuel injection amount by correcting the basic injection amount Tp according to the operation condition signal with the feedback correction coefficient α, a device 63 for supplying the fuel of this injection amount, and a canister. A purge valve 64 for adjusting a flow rate of a passage for introducing the adsorbed fuel into the intake pipe together with fresh air in accordance with a drive signal, and a low water temperature during the air-fuel ratio feedback correction and before the completion of warm-up of the catalyst is set as a purge condition. Means 47 for determining whether or not the purge condition is satisfied, and means 65 for calculating the purge valve opening PV from the fuel concentration A in the purge gas under the purge condition based on the determination result. , Means 66 for outputting a drive signal corresponding to the purge valve opening PV in 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 air-fuel ratio feedback correction coefficient α and the purge valve opening are being determined based on the determination result during the purge and the air-fuel ratio feedback correction. A means 68 for calculating the fuel concentration A in the purge gas based on the PV, and a means 69 for judging whether or not the purge is being performed, the air-fuel ratio feedback correction is being performed, and the temperature of the catalyst is at a low water temperature before completion of warm-up. The fuel of the purge gas is purged based on the fuel concentration A in the purge gas and the air-fuel ratio feedback correction coefficient α at the time of low water temperature before the completion of the warm-up of the catalyst during the purging and the air-fuel ratio feedback correction based on the determination result. a means 70 for calculating the ratio R _EVAP, large enough which increases according to the fuel ratio R _EVAP this purge gas Means 71 for calculating the retardation correction amount ΔADV, means 72 for calculating the ignition timing ADV by retarding the basic ignition timing ADV0 with the retardation correction amount ΔADV, and sparking at the ignition timing ADV. Means 51 for outputting an ignition signal to the ignition device 52 as described above.

In a third aspect based on the second aspect, the purge valve opening is increased and corrected at a low water temperature before the completion of the warm-up of the catalyst.

According to a fourth aspect of the present invention, as shown in FIG. 26, a lean target air-fuel ratio basic value Tfbya0 under a lean condition.
81 in accordance with an operation condition signal, a purge valve 46 for opening and closing a passage for introducing fuel adsorbed in the canister into the intake pipe together with fresh air in response to a drive signal,
A means for determining whether or not the lean condition is a purge condition, and a means for opening the purge valve under the purge condition based on the determination result.
Means 83 for determining whether the purging is being performed and the lean condition is satisfied, and correcting the target air-fuel ratio Tfbya to the lean side by correcting the basic value Tfbya0 of the target air-fuel ratio to the lean side under the purging and the lean condition based on the determination result. Means 8 for calculating
4, the means 85 for calculating a fuel injection amount in the lean conditions the basic injection amount Tp in accordance with the operating condition signal at the target air-fuel ratio Tfbya is corrected, the device 63 for supply feeding the fuel of the injection amount Was provided.

According to a fifth aspect of the present invention, as shown in FIG. 27, a sensor 42 for detecting the oxygen concentration in the exhaust gas, and based on the sensor output, the exhaust air-fuel ratio becomes stoichiometric under non-lean conditions and air-fuel ratio feedback conditions. Means 91 for calculating an air-fuel ratio feedback correction coefficient α so as to match the fuel ratio, a purge valve 64 for adjusting the flow rate of a passage for introducing fuel adsorbed by the canister into the intake pipe together with fresh air in accordance with a drive signal, and a lean valve. Means 81 for calculating basic value Tfbya0 of the target air-fuel ratio on the lean side according to the operating condition signal under the condition
Means 92 for determining whether the lean condition is a first purge condition and a low load condition after completion of warm-up of the engine during the air-fuel ratio feedback correction as a second purge condition to determine whether these purge conditions are satisfied; A means 65 for calculating the purge valve opening PV from the fuel concentration A in the purge gas under the purge conditions based on the determination result, and the purge valve opening P
Means 66 for outputting a drive signal corresponding to V to the purge valve 64; means 93 for determining whether the purge is being performed under the second purge condition, the non-lean condition is being performed, and the air-fuel ratio feedback correction is being performed, From this determination result, the fuel concentration in the purge gas is determined based on the air-fuel ratio feedback correction coefficient α and the purge valve opening PV during the purge under the second purge condition, during the non-lean condition, and during the air-fuel ratio feedback correction. A calculating means 94; means 95 for determining whether the purging is being performed under the first purge condition and whether or not the lean condition is satisfied; Under the conditions, the fuel ratio R _{E of the} purge gas is determined based on the fuel concentration A in the purge gas and the basic value Tfby0 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 correcting the basic value Tfbya0 of the target air-fuel ratio to the lean side with the air-fuel ratio correction amount ΔTfbya to obtain the target air-fuel ratio Tfbya.
means 98 for calculating fbya, and the target air-fuel ratio T during purging under the first purge condition and under the lean condition.
fbya, and under the non-lean condition and the air-fuel ratio feedback condition, the air-fuel ratio feedback correction coefficient α
In correcting the basic injection amount in accordance with each operating condition signal and means 99 for calculating a fuel injection amount, the fuel of the injection amount
It provided a device 63 for test sheet.

[0017] A sixth invention is as shown in FIG. 28, E
A means 112 for calculating a basic EGR valve opening degree V _EGR 0 according to the operating condition signal under the GR condition, a sensor 42 for detecting the oxygen concentration in the exhaust gas, and based on the sensor output, the exhaust air-fuel ratio and the stoichiometric air-fuel ratio A means 91 for calculating an air-fuel ratio feedback correction coefficient α so as to match, and a basic injection amount T corresponding to an operation condition signal using the feedback correction coefficient α.
a means 62 for calculating a fuel injection amount by correcting the p, a device 63 for supply supplying a fuel of the injection amount, the flow rate of the passage for introduction into the intake pipe together with fresh air and fuel adsorbed to a canister to a drive signal A purge valve 64 that is adjusted accordingly; a means 121 for determining whether or not the purge condition is set during the EGR and the air-fuel ratio feedback correction; and a fuel concentration A in the purge gas under the purge condition based on the determination result. A means 65 for calculating the purge valve opening PV; a means 66 for outputting a drive signal corresponding to the purge valve opening PV to the purge valve 64;
Means 122 for judging whether or not the engine is in the GR state, and based on the air-fuel ratio feedback correction coefficient α and the purge valve opening PV during the purge, the air-fuel ratio feedback correction and the EGR based on the judgment result, Means 123 for calculating the fuel concentration A in the purge gas during the purge and the air-fuel ratio feedback correction and during the EGR based on the fuel concentration A in the purge gas and the air-fuel ratio feedback correction coefficient α. a means 124 for calculating the R _EVAP, a means 125 for calculating a larger opening correction amount [Delta] V _EGR this much larger response to fuel ratio R _EVAP this purge gas, the basic EGR valve opening in the opening correction amount [Delta] V _EGR V _EGR 0
The a means 126 for calculating the increase correction to the EGR valve opening degree V _EGR, provided with means 116 for outputting a signal corresponding to the EGR valve opening V _EGR to the EGR valve 111.

[0018]

Since the purge gas has high volatility, 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 are improved. Therefore, the air-fuel ratio is corrected by the air-fuel ratio feedback correction. Even in a state where it is kept constant, the surge limit expands in the direction of retarding the ignition timing.

By utilizing this characteristic, if the ignition timing is corrected at a low water temperature during the purging and before the completion of the warm-up of the catalyst in the first invention, the exhaust performance is improved by an increase in the exhaust temperature. And no surge occurs.

In the second 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 the air-fuel ratio feedback correction. The fuel concentration A in the purge gas and the air-fuel ratio feedback correction coefficient α at the time of low water temperature during the feedback correction and before the completion of the warm-up of the catalyst.
Based on preparative fuel ratio R _EVAP purge gas is calculated, the retard correction amount ΔADV be large enough which increases according to the fuel ratio R _EVAP the purge gas is calculated,
When the basic ignition timing ADV0 is retarded by the retardation correction amount ΔADV, the retardation correction amount ΔADV is provided without excess or deficiency even if the fuel concentration A in the purge gas is different, in addition to the operation of the first invention. Can be

In the third invention, when the purge valve opening is increased and corrected at the time of low water temperature before the completion of warming up of the catalyst, the amount of retard correction of the ignition timing is further increased, thereby adding to the effect of the second invention. As a result, the warm-up of the catalyst is further promoted.

According to the fourth aspect of the present invention, when the purge gas is introduced under a lean condition, and the target air-fuel ratio is corrected to the lean side during the purge, the fuel efficiency is improved and a surge is generated by the improvement in combustion due to the introduction of the purge gas. Nor.

According to a fifth aspect of the present invention, the lean condition is defined as a first purge condition, and the air-fuel ratio feedback correction is performed under a low load after the completion of warm-up of the engine as a second purge condition. During the medium and non-lean conditions and during 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 during the purge under the first purge condition and the lean condition. 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
, The air-fuel ratio correction amount Δ that becomes smaller as this becomes larger
Tfbya is calculated, and the air-fuel ratio correction amount ΔTfbya
When the basic value Tfbya0 of the target air-fuel ratio is corrected to the lean side, even if the fuel concentration A in the purge gas is different, the air-fuel ratio correction amount ΔTfbya is provided without excess or deficiency in addition to the operation of the fourth invention.

In the sixth 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, the air-fuel ratio feedback correction and the EGR, and 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 which increases as the ratio increases according to the fuel ratio R _{EVAP of the} purge gas is calculated. The basic EGR valve opening V _EGR 0 is increased by the degree correction amount ΔV _EGR .

Here, the fuel ratio of the purge gas depends on the engine.
Fuel amount (fuel amount in purge gas and fuel supply
Fuel in the purge gas against the sum of the amount of fuel from the feeder)
The amount of fuel in the purge gas
Is calculated according to the fuel concentration A in the purge gas
Even if the amount of fuel from the fuel supply device is the same
If the fuel concentration A in the purge gas is different, the fuel of the purge gas
The ratio R _EVAP changes, which _{results in} the opening of the EGR valve
The correction amount ΔV _EGR is different, and the fuel amount in the purge gas is
Even under the same conditions, depending on the operating conditions,
The fuel ratio R _{EVAP of the} purge gas changes if the amount of fuel
As a result, the EGR valve opening correction amount ΔV _EGR becomes
Will be different.

As described above, the fuel concentration A in the purge gas and the fuel concentration A
Purge gas that varies depending on the amount of fuel from the fuel supply unit
EGR valve opening correction amount ΔV according to the fuel ratio
_{Once EGR} is calculated, improve combustion by introducing purge gas.
The EGR rate increases by the amount, and the combustion temperature decreases, resulting in NO
The x emission amount is reduced, and even if the fuel concentration A in the purge gas or the fuel amount from the fuel supply device is different, the opening correction amount ΔV _EGR is given without excess or deficiency.

[0027]

In FIG. 2, air sucked from an air cleaner 3 is temporarily stored in a collector portion 2a having a fixed volume, and flows into each cylinder through a branch pipe. An injector 4 is provided at an intake port 2b of each cylinder, and fuel is intermittently injected from the injector 4 in synchronization with engine rotation. The 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 injection amount increases as the injection time from the injector 4 increases, and the injection amount decreases as the injection time decreases. 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 certain 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 with the intake air flow rate becomes a constant value, the same air-fuel ratio can be obtained even when the operating conditions are different. When fuel injection is intermittently performed once for one revolution of the engine, the basic injection pulse width Tp is calculated from the intake air flow rate Qa at that time and the engine speed Ne for the amount of air sucked in one revolution. = (Qa / Ne) × K # (2) where K # is determined by an equation of 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.

The exhaust pipe 5 contains 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 the three harmful components simultaneously only when the exhaust air-fuel ratio is in a narrow range around the stoichiometric air-fuel ratio. In order to keep the air-fuel ratio in this range, the control unit 11 performs feedback correction of 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, immediately after the start of the engine, the air-fuel ratio feedback correction is not performed, and the drivability is prioritized by improving the combustion state by the water temperature increase correction and the post-start increase correction.

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 The invalid pulse width. Α = 1 from the start of the engine until immediately after
From 00%, Ti = Tp × (1 + Ktw + Kas) + Ts where Ktw; water temperature increase correction coefficient Kas; post-start increase correction coefficient, and when the air-fuel ratio feedback condition is satisfied, the fuel injection pulse is expressed by Ti = Tp × α + Ts The width Ti is calculated.

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

In the control unit 11, a reference signal Ref for the crank angle is output from the crank angle sensor 12.
(For example, a signal that rises at 66 ° before the compression top dead center) and a 1 ° signal for each unit angle are input. To ignite at, for example, 30 ° before the compression top dead center, the reference signal Ref is received. At the same time, the 1 ゜ signal is counted 36 (= 66−30) times, and then 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 on the activated carbon in the canister 23. Reference numeral 24 denotes a check valve for preventing 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.
6, a normally closed purge valve 27 driven by a step motor is provided.

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

The reason why the normally closed diaphragm actuator 28 is provided in series with the purge valve 27 is to provide fail-safe operation when the purge valve 27 fails. When the purge valve 27 is opened due to a failure, a purge gas (a mixed gas of evaporative fuel separated from the activated carbon and fresh air) is introduced even during warm-up or the like, and the mixture becomes excessively rich. Become. Therefore, under the non-purge condition, the normally closed diaphragm actuator 28 causes the passage 2 to pass.
By shutting off 6, the purge gas is prevented from being introduced into the intake pipe 2 under conditions other than the purge conditions.

It is to be noted that the purge cut valve 2 is provided under the purge condition.
9 are simultaneously opened, and the suction negative pressure downstream of the throttle valve 25 is
Through the diaphragm actuator 28, the diaphragm is pulled against the return spring by this negative pressure, and the passage 26 is opened.

The O ₂ sensor 7 has a heater (heating means). The control unit 11 does not wait for the O ₂ sensor 7 to be heated and activated by exhaustion. By activating the O ₂ sensor 7 at an early stage, feedback correction of the air-fuel ratio is started from a low water temperature where the cooling water temperature Tw is 25 ° C. or less. At the start of the feedback correction, the water temperature increase correction and the post-start increase correction are ended.

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

In order to cope with this, the control unit 11 improves the combustion state at the time of low water temperature by introducing the purge gas with the low water temperature as a purge condition during the air-fuel ratio feedback correction by using the purge gas having high volatility.
By delaying the ignition timing by the amount corresponding to the combustion improvement, the exhaust gas temperature is raised to promote the warm-up of the catalyst.

The sensors required for such control are the same as those required for normal air-fuel ratio control and ignition timing control, and include an air flow meter 13 for outputting an output according to the intake air flow rate, and detection of a 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 flowchart showing the control of the purge valve 27 and the purge cut valve 29, FIG. 7 is a flowchart showing the calculation of the fuel concentration in the purge gas, and FIG. 9 is a flowchart showing the calculation of the ignition timing, which are performed at a constant cycle (for example, 100 msec). The processing is performed in the order of 3 → FIG. 7 → FIG.

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 FIGS. 3, 7, and 9.

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

The purge conditions are as follows: <1> At low load after completion of engine warm-up. <2> During air-fuel ratio feedback correction and cooling water temperature is 60
This is one of the cases when the water temperature is lower than ℃. <1> is the same as the conventional one. Unlike the conventional case, the reason why <2> is added is to improve the combustion state by introducing a highly volatile purge gas under these conditions.

When the purge condition is satisfied, the fuel concentration A in the purge gas (to be described later with reference to FIG. 7) is read from the memory in step 4 and the basic purge valve opening degree is determined based on the fuel concentration A with reference to the table shown in FIG. Find PV0. As shown in FIG. 4, the characteristic of the basic purge valve opening PV0 is made substantially inversely proportional in order to make the flow rate of the fuel passing through the purge valve 27 substantially constant even if the fuel concentration in the purge gas is different. .

In steps 5 and 6, the cooling water temperature Tw is calculated from FIG.
Is calculated with reference to a table having the following contents, and the purge valve opening PV is calculated by the following equation in order to increase and correct the basic purge valve opening PV0 by the following equation: PV = PV0 × Kpv (4).

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

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

Since the above-mentioned purge valve opening PV is required in FIG.
Store V in memory.

In FIG. 7, it is determined whether or not the purging is being performed in steps 11 and 12 and whether or not the air-fuel ratio feedback correction is being performed. Calculate the fuel concentration inside.

The conditions for stopping the air-fuel ratio feedback correction are, for example, at the time of starting, at a high load, and when the O ₂ sensor is abnormal. The reason for estimating the fuel concentration in the purge gas on the condition that the air-fuel ratio feedback correction is being performed is that the air-fuel ratio feedback correction coefficient α changes under this condition (when the fuel concentration in the purge gas is higher than the stoichiometric air-fuel mixture). Changes to the side where α becomes smaller than 100%, and conversely, to the side where α becomes larger than 100% when the mixture is thinner than the stoichiometric air-fuel ratio), the change in α corresponds to the purge gas fuel concentration. Because you do.

Therefore, in step 13, the difference Δα [%] between the air-fuel ratio feedback correction coefficient α [%] during purge and the average value of α (α100%) during non-purge is calculated as follows: Δα = α−100 5) It is calculated by the following equation. The value of Δα is 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, the fuel concentration in the purge gas can be estimated without performing the air-fuel ratio feedback correction.

In steps 14 and 15, the air flow rate Q _EVAP in the purge gas [kg / kg] is referred from the purge valve opening PV stored in the memory with reference to the table containing FIG.
h], and using the air flow rate Q _EVAP in the purge gas and the above difference Δα and the intake air flow rate Qa [kg / h], the fuel concentration A [absolute 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 the control is performed so that the air-fuel ratio matches the stoichiometric air-fuel ratio (14.7), the fuel flow rate during the purge and the air flow rate during the purge are expressed by (fuel flow rate during the purge) / (purge rate). Medium air flow rate) = 1 / 14.7 (8)

Here, the fuel flow rate during purge and the air flow rate during purge are: fuel flow rate during purge = fuel flow rate in purge gas + fuel flow rate from injector = Q _EVAP × A + Qa × (1 / 14.7) × (Δα + 100) / 100 (9) Air flow during purge = air flow in purge gas + air flow through air flow meter = Q _EVAP + Qa (10) _Therefore , when these are substituted into the expression (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 Equation (6) above is obtained A.

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 determined from this and the engine speed Ne by referring to the map shown in FIG. . The basic ignition timing ADV0 is a value matched during non-purge, and is the same as the conventional one.

At steps 23, 24 and 25, the following conditions are satisfied: <3> Purging is being performed; <4> Air-fuel ratio feedback correction is being performed; and <5> Cooling water temperature Tw is a low temperature of 60 ° C. or less. If any of the conditions is not satisfied, the routine proceeds to steps 26 and 27, where the basic ignition timing ADV0 is directly entered into a variable ADV representing the ignition timing given to the power transistor, and this is stored in the output register. Forward.

When all of 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 calculated by the following equation: Ginj = Qa × (1 / 14.7) × α (12), and the air flow rate Q in the purge gas. _{Using EVAP} and the fuel concentration A, the fuel flow rate G _EVAP in the purge gas is calculated by the following equation: G _EVAP = Q _EVAP × A (13)
The calculating formula of _{R EVAP = G EVAP / (Ginj} + G EVAP) ... (14) EVAP.

In steps 31 and 32, the fuel ratio R
_The retardation correction amount ΔADV is obtained from the EVAP with reference to the table having the contents shown in FIG. 11, and a value obtained by subtracting the retardation correction amount ΔADV from the basic ignition timing ADV0 is entered in the variable ADV. Since the ignition timing indicates a value before the compression top dead center, the basic ignition timing A
By subtracting the correction amount ΔADV from DV0, the ignition advance value can be retarded.

Here, the operation of this example will be described.

Although gasoline as a fuel is a mixture of a very large number of hydrocarbon molecules, what is adsorbed on the canister 23 is methane or ethane, which has a small number of carbon atoms, and is easily vaporized. Nature,
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. Therefore, 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 by air-fuel ratio feedback correction (indicated by stoichiometry in the figure), and as the fuel flow rate in the purge gas increases (the fuel concentration increases), the surge limit increases in the retard direction of the ignition timing. . That is, when the purge gas is being introduced, even if the ignition timing is retarded from the time when the purge gas is not purged, a surge does not occur and the operability does not deteriorate.

Using this characteristic, in this example, if the purge gas is introduced into the intake pipe at the time of feedback correction of the air-fuel ratio and at a low water temperature of 25 to 60 ° C., and the ignition timing is corrected from the non-purge state, the ignition timing is retarded. The exhaust temperature is raised by the amount of retarding the ignition timing from the time of non-purge while maintaining good operability, so that activation of the catalyst can be promoted (exhaust performance can be improved).

Further, the fuel concentration A in the purge gas is obtained based on the air-fuel ratio feedback correction coefficient α and the purge valve opening A during the purge and the air-fuel ratio feedback correction.
The fuel ratio R _EVAP of the purge gas is obtained 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 not more than 0 ° C.
_Since the retardation correction amount ΔADV of the ignition timing is increased as EVAP becomes higher, the retardation correction amount ΔADV can be provided without excess or shortage even if the fuel concentration A in the purge gas is different. As shown in FIG. 13, the exhaust gas temperature can be increased according to the purge gas fuel ratio R _EVAP .

Further, at the time of low water temperature immediately after the start of the catalyst 6 when the activity of the catalyst 6 becomes insufficient, the opening of the purge valve is increased and a large amount of highly volatile purge gas is supplied so that the ignition timing retard correction amount ΔADV Can be further increased, whereby the warm-up of the catalyst can be further promoted.

On the other hand, in order to improve the drivability, the air-fuel ratio feedback correction is stopped immediately after the cold start and immediately thereafter, and the fuel amount is increased to supply an air-fuel mixture richer than the stoichiometric air-fuel ratio. Improving combustion by introducing highly volatile purge gas from the start to immediately after, improving operability and reducing HC at the catalyst inlet, and reducing the amount of fuel by the amount of purge gas introduced By doing so, fuel efficiency is also improved. However,
Since the O ₂ sensor does not output a normal output from the time of the cold start when the air-fuel ratio feedback correction is stopped until immediately thereafter, instead of the O ₂ sensor when introducing the purge gas also from the time of the cold start to immediately thereafter. It goes without saying that the fuel ratio of the purge gas must be calculated using the wide area air-fuel ratio sensor.

Next, 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 target air-fuel ratio.
In the operating range where the output is insufficient (non-lean condition),
In a lean burn engine that performs feedback correction of the air-fuel ratio with the stoichiometric air-fuel ratio as the target 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 economy. On the other hand, as shown in FIG. 12, the expansion of the surge region due to the highly volatile purge gas also occurs in the air-fuel ratio. Even if the ignition timing is the same, the surge region expands to the lean side during the purge. By correcting the air-fuel ratio to the lean side, no surge occurs.

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. 15 corresponding to FIG. 9 and showing the calculation of the fuel injection pulse width Ti given to FIG.

First, the purge conditions in this example are different from those in the previous embodiment. In the case of either <6> 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 described later, the fuel concentration A is calculated and stored during the purging, the non-lean condition, and the air-fuel ratio feedback correction in the case of <6>, and <7> The fuel concentration A is read out and used under the purge condition and under the lean condition in the case of (1). In the case of <6>, the fuel concentration is calculated because the difference Δα cannot be calculated unless the air-fuel ratio feedback correction is being performed because of the configuration using the O ₂ sensor.

In FIG. 14, steps 41, 42, 4
In step 3, it is determined whether the following conditions are satisfied: <8> purging, <9> non-lean conditions, and <10> air-fuel ratio feedback correction is being performed. Then, the fuel concentration A in the purge gas is calculated in the same manner 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 purging is being performed and whether a lean condition is satisfied. The lean condition is, for example, that the cooling water temperature Tw is 80 ° C.
This is when all the conditions that the throttle valve opening from the throttle sensor is equal to or less than a predetermined value and that the vehicle speed change is equal to or less than a predetermined value are satisfied.

If the engine is being purged and the engine is in the lean condition, the target fuel-air ratio map value Tfbya0 in the lean condition is determined in step 54 from the engine speed Ne and the basic injection pulse width Tp with reference to the lean map shown in FIG. Ask.

When the value of the target fuel-air ratio map value Tfbya0 is 1.0, it corresponds to the stoichiometric air-fuel ratio. As shown in FIG. 16, when the value is smaller than 1.0, the air-fuel ratio on the lean side is obtained. . In addition, the 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. , Fuel-air ratio.

[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 correction amount ΔTfbya by the value of the target fuel-air ratio map value Tfbya0 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 reduce the target fuel-air ratio by multiplying the map value Tfbya by the correction amount ΔTfbya (correcting 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 following 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) are the same values as in the previous embodiment.

As described above, by introducing the purge gas under the lean condition and correcting the target air-fuel ratio under the lean condition to the lean side, the fuel efficiency can be further improved without generating a surge.

During the air-fuel ratio feedback correction, the fuel concentration A in the purge gas is reduced during the purge at a low load (second purge condition) after the completion of the warm-up of the engine (non-lean condition and the air-fuel ratio feedback correction). During the purging under the lean condition (first purge condition) and under the lean condition, 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, fuel efficiency can be improved in accordance with 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 that recirculates inactive exhaust gas to the intake pipe in order to suppress the generation of the exhaust gas. This device is
EGR passage 10 communicating intake pipe 101 and exhaust pipe 102
3. EGR for adjusting the gas flow rate in the passage 103
The valve 104 includes a negative pressure control valve 105 for adjusting a control negative pressure to the EGR valve 104.

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 introduces air into the constant negative pressure. And a solenoid valve 105b for generating a control negative pressure to the EGR valve 104, and the flow rate of the EGR valve is turned off to the solenoid valve 105b.
Since the duty ratio is determined substantially in proportion to the duty (the ratio of the valve closing time in a constant cycle) (the larger the OFF duty, the larger the EGR flow rate), the OFF duty is adopted as a control value for the solenoid valve 105b.

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

The third embodiment is an application example of the present invention for such EGR control. When a purge gas is introduced during EGR, the combustion state is improved.
The R rate can be increased, and the combustion temperature can be reduced accordingly, and the NOx emission can be reduced.

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

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

Referring to FIGS. 20 and 21, it is checked in step 71 whether or not the EGR condition is satisfied. Conditions for cutting the EGR are as follows: when the engine is started, when the engine is idling, when the engine is decelerated, and when the coolant temperature is within a predetermined range (for example, 60 ° C.
0 ° C. or less), and other operating conditions are EG
This is the R condition.

When the EGR condition is satisfied, the routine proceeds to step 72, where the basic injection pulse width Tp and the engine speed Ne are used as shown in FIG.
The basic EGR valve opening V _EGR 0 is obtained with reference to a map containing 2 as a reference.

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

In steps 81 and 82 in FIG. 20, an opening correction amount ΔV _EGR is obtained from the fuel ratio R _EVAP with reference to the table 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 _VEGR .

In FIG. 23, the reason why the value of the opening correction amount ΔV _EGR is reduced in a region where the fuel ratio R _EVAP is small with two gradients of the characteristic is to provide a dead zone.
If the fuel ratio R _EVAP does not increase to some extent, the opening correction amount ΔV _EGR is not increased.

[0096] The EGR valve opening V _EGR in step 83 and 84 with reference to the table that the content of Figure 24 was converted to the OFF duty D _OFF of the solenoid valve 105b, and transfers it to the output register.

As described above, in this example, the purge gas is introduced as a purge condition during the EGR and during the air-fuel ratio feedback correction, and the EGR valve opening is increased and corrected during the purge and during the EGR condition and the air-fuel ratio feedback correction. In addition, the EGR rate can be increased by an amount corresponding to the improvement of the combustion state by the introduction of the purge gas, whereby the combustion temperature is lowered and the NOx emission can be reduced.

During the purge, the EGR, and the air-fuel ratio feedback correction, the air-fuel ratio feedback correction coefficient α
And the fuel concentration A in the purge gas on the basis of the purge valve opening PV, further obtains a fuel ratio R _EVAP purge gas based on the fuel concentration A and the air-fuel ratio feedback correction coefficient alpha, depending on the fuel ratio R _EVAP Since the opening degree correction amount ΔV _EGR is obtained and the basic EGR valve opening degree V _EGR 0 is corrected by this, the opening degree correction amount ΔV _EGR can be provided without excess or shortage even if the fuel concentration A in the purge gas is different.

In the third embodiment, the EGR valve opening is set as the control amount, but the EGR rate may be set as the control amount.

[0100]

According to the first aspect of the present invention, 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 the heating means are used. Means for early activation of the sensor at the time of start-up, and 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 the time of low water temperature before the completion of catalyst warm-up. A purge valve that opens and closes a passage for introducing the fuel adsorbed in the canister into the intake pipe together with fresh air according to a drive signal, and a purge condition during the air-fuel ratio feedback correction and at a low water temperature before the completion of the warm-up 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 judging whether or not it is at the time of low water temperature, means for calculating the ignition timing by retarding the basic ignition timing at the low water temperature during purging and before the completion of the warm-up of the catalyst from the judgment result, A means for outputting an ignition signal to the igniter so that the sparks fly at this ignition timing is provided, so that the exhaust performance is increased by an amount corresponding to the increase in the exhaust temperature with the ignition timing retard correction without generating a surge. Can be improved.

According to a second aspect of the present invention, there is provided 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 start-up operation using the heating means. A means for activating the sensor at an early stage, and a means for calculating an air-fuel ratio feedback correction coefficient such that the air-fuel ratio matches the stoichiometric air-fuel ratio from the time of low water temperature before the completion of the warm-up of the catalyst based on the sensor output. means for calculating a fuel injection amount of the basic injection amount in accordance with the operating condition signal with the feedback correction coefficient correcting the, the device for supply supplying a fuel of the injection amount, together with fresh air and fuel adsorbed to a canister intake A purge valve for adjusting the flow rate of the passage introduced into the pipe in accordance with the drive signal, and a purge condition during the low fuel temperature during the air-fuel ratio feedback correction and before the completion of warm-up of the catalyst. Means for determining whether a 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 determining whether the air-fuel ratio feedback correction coefficient and the purge valve opening degree are being purged and the air-fuel ratio feedback correction is being performed based on the determination result. Means for calculating the fuel concentration in the purge gas based on the above, means for judging whether the purge is being performed, the air-fuel ratio feedback correction is being performed, and whether or not the catalyst is at a low water temperature before the completion of warm-up of the catalyst. At the time of low water temperature during purging and during the air-fuel ratio feedback correction and before completion of warm-up of the catalyst Means for calculating a fuel ratio of the purge gas based fuel concentration in the purge gas to said air-fuel ratio feedback correction coefficient,
Means for calculating a retardation correction amount which increases in accordance with the fuel ratio of the purge gas, and means 72 for calculating the ignition timing by retarding the basic ignition timing with the retardation correction amount; Means for outputting an ignition signal to the ignition device so that the sparks fly. Therefore, in addition to the effect of the first invention, even if the fuel concentration in the purge gas is different, the amount of retard correction can be adjusted without excess or deficiency. Can be given.

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

The fourth aspect of the present invention provides a means for calculating a basic value of a target air-fuel ratio on the lean side under a lean condition in accordance with an operation condition signal, and a passage for introducing fuel adsorbed by the canister into the intake pipe together with fresh air. A purge valve that opens and closes in response to a drive signal, a unit that determines whether or not the purge condition is the lean condition, a unit that opens the purge valve under the purge condition based on the determination result, Means for determining whether or not 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 during purging and under the lean condition based on the determination result, and means for calculating a fuel injection amount in the lean condition by correcting the basic injection amount in accordance with the operating condition signal, since there is provided an apparatus and to supply feed fuel of the injection amount 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 provides a sensor for detecting the oxygen concentration in exhaust gas, and an air-fuel ratio feedback based on the sensor output so that the exhaust air-fuel ratio matches the stoichiometric air-fuel ratio under non-lean conditions and air-fuel ratio feedback conditions. Means for calculating a correction coefficient, a purge valve for adjusting a flow rate of a passage for introducing the fuel adsorbed in the canister into the intake pipe together with fresh air according to a drive signal, and a basic value of a target air-fuel ratio on the lean side under lean conditions. Means for calculating in accordance with an operating condition signal; these purge conditions being the first purge condition, the lean condition being a first purge condition, and the second purge condition being a low load condition after completion of warm-up of the engine during air-fuel ratio feedback correction. Means for determining whether the purge valve is open from the fuel concentration in the purge gas under purge conditions based on the determination result. Means for outputting a drive signal corresponding to the opening degree of the purge valve 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, The fuel concentration in the purge gas is calculated based on the air-fuel ratio feedback correction coefficient and the purge valve opening during the purge under the second purge condition, during the non-lean condition, and during the air-fuel ratio feedback correction from the determination result. Means for determining whether the purge condition is being satisfied during the purging under the first purge condition and whether the condition is 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; 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 the air-fuel ratio correction amount; During the purging under the first purge condition and the lean condition, the basic injection amount corresponding to the operating condition signal is corrected by the target air-fuel ratio at the target air-fuel ratio and under the non-lean condition and the air-fuel ratio feedback condition by the air-fuel ratio feedback correction coefficient. and means for calculating a fuel injection amount, since there is provided an apparatus and to supply feed fuel of the injection amount, in addition to the effect of the fourth invention, even when the fuel concentration in the purge gas differs, the air-fuel ratio correction The amount can be given without excess or shortage.

According to a sixth aspect of the present invention, there is provided means for calculating a basic EGR valve opening degree according to an operating condition signal under EGR conditions, a sensor for detecting an oxygen concentration in exhaust gas, and an exhaust air-fuel ratio based on the sensor output. Means for calculating an air-fuel ratio feedback correction coefficient so as to match the stoichiometric air-fuel ratio; means for correcting the basic injection amount corresponding to the operating condition signal with the feedback correction coefficient to calculate the fuel injection amount; a device for supply supplying a fuel, purge the purge valve for adjusting in response to the drive signal the flow rate of the passage for introduction into the intake pipe together with fresh air and fuel adsorbed in the canister, a and in the air-fuel ratio feedback correction in the EGR condition Means for determining whether or not the purge condition is satisfied, and the purge valve opening degree is determined from the fuel concentration in the purge gas under the purge condition based on the determination result. Means for calculating, means for outputting a drive signal corresponding to the opening degree of the purge valve to the purge valve, means for judging whether the purging is being performed, the air-fuel ratio feedback correction is being performed, and the EGR is being performed. Means for calculating a fuel concentration in the purge gas based on the air-fuel ratio feedback correction coefficient and the purge valve opening during the purge and the air-fuel ratio feedback correction and during the EGR; and the air-fuel ratio feedback correction during the purge. 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 the EGR, and an opening correction amount that increases as the fuel ratio of the purge gas increases according to the fuel ratio. Means for calculating, and the basic EGR valve Means for calculating an EGR valve opening the opening increasing correction to, since a signal corresponding to the EGR valve opening is provided and means for outputting to the EGR valve, partial combustion improvement by introduction of purge gas
NOx emissions by increasing the EGR rate and lowering the combustion temperature
Fuel concentration in the purge gas and fuel supply
Thus, even if the fuel amount differs, the opening correction amount can be given without excess or deficiency.

[Brief description of the drawings]

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

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

FIG. 3 is a flowchart 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 ratio 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 flowchart for explaining calculation of a fuel concentration A;

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

FIG. 9 is a flowchart for explaining calculation of an ignition timing ADV.

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

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

FIG. 12 is a characteristic diagram showing a surge limit at the time of purge and at the time of non-purge.

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

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

FIG. 15 is a flowchart for explaining calculation of a fuel injection pulse width Ti according to 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 illustrates OF applied to a solenoid valve 105b according to a third embodiment.
9 is a flowchart for explaining calculation of an F duty D _OFF .

FIG. 21 is a diagram showing an example of OF applied to a solenoid valve 105b according to the third embodiment.
9 is a flowchart for explaining calculation of an F duty D _OFF .

FIG. 22 is a characteristic diagram of a basic EGR valve opening _VEGR .

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 _VEGR .

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

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

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

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

[Explanation of symbols]

Reference Signs List 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 means 70 Fuel split Calculation means 71 Delay angle correction amount calculation means 72 Ignition timing calculation means 81 Basic value calculation means 82 Purge condition judgment means 83 Judgment 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 Determination means 93 determination means 94 fuel concentration calculation means 95 determination 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 calculating means 116 Valve opening signal output means 121 Purge condition determining means 122 Determining means 123 Fuel concentration calculating means 124 Fuel ratio calculating means 125 Opening correction amount calculating means 126 EGR valve opening calculating means

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁷ Identification code FI F02D 43/00 301 F02D 43/00 301E 301M 301N F02M 25/07 550 F02M 25/07 550R F02P 5/15 F02P 5/15 BE (58) Field surveyed (Int.Cl. ⁷ , DB name) F02M 25/08 301 F02D 41/02 301 F02D 41/14 310 F02D 43/00 301 F02M 25/07 550 F02P 5/15

Claims (6)

(57) [Claims] 1. A means for calculating a basic ignition timing according to an operation condition signal; a sensor for detecting an oxygen concentration in exhaust gas; a means for heating the sensor; Means for early activation; means for performing air-fuel ratio feedback correction so that the air-fuel ratio matches the stoichiometric air-fuel ratio from the time of low water temperature before the completion of catalyst warm-up based on the sensor output; and A purge valve that opens and closes a passage for introducing fuel into the intake pipe together with fresh air according to a drive signal; and whether the purge condition is a purge condition when the air-fuel ratio feedback correction is being performed and the low water temperature before the completion of warming up of the catalyst is performed. Means for determining whether or not the purge valve is opened under purge conditions based on the result of the determination; and Means for determining whether or not there is, based on the result of the determination, means for delay-correcting the basic ignition timing at low water temperature before purging of the catalyst and before completion of warm-up of the catalyst to calculate the ignition timing; Means for outputting an ignition signal to the igniter so as to fly. 2. A means for calculating a basic ignition timing according to an operation condition signal; a sensor for detecting an oxygen concentration in exhaust gas; a means for heating the sensor; Means for early activation; 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 the time of low water temperature before the completion of catalyst warm-up; means for calculating a correction to the fuel injection amount basic injection quantity in accordance with the operating condition signal in a device for supply feeding the fuel of the injection amount, is introduced into the intake pipe together with fresh air and fuel adsorbed to a canister A purge valve for adjusting a flow rate of the passage according to a drive signal; and Means for judging whether or not the condition is satisfied, means for calculating the purge valve opening from the fuel concentration in the purge gas under purge conditions based on the judgment result, and means for outputting a drive signal corresponding to the purge valve opening to the purge valve Means for determining whether the purging is being performed and the air-fuel ratio feedback correction is being performed; and, based on the result of the determination, determining whether the air-fuel ratio feedback correction coefficient and the purge valve opening degree are being purged and the air-fuel ratio feedback correction is being performed. A means for calculating a fuel concentration in the purge gas based on the result; a means for determining whether the purge is being performed, the air-fuel ratio feedback correction is being performed, and whether or not the catalyst is at a low water temperature before completion of warm-up of the catalyst; During the purge and during the air-fuel ratio feedback correction and at a low water temperature before the completion of the warm-up of the catalyst, A means for calculating a fuel ratio of the purge gas based on the fuel concentration in the purge gas and the air-fuel ratio feedback correction coefficient; a means for calculating a retard correction amount that increases in accordance with the fuel ratio of the purge gas and increases as the fuel ratio increases; An engine provided with means for delay-correcting the basic ignition timing by an angle correction amount to calculate an ignition timing, and means for outputting an ignition signal to an ignition device so that a spark jumps at the ignition timing. Evaporative fuel processing equipment. 3. The evaporative fuel treatment system for an engine according to claim 2, wherein the purge valve opening is increased and corrected at a low water temperature before the completion of warming up of the catalyst. 4. A means for calculating a basic value of a lean target air-fuel ratio under a lean condition in accordance with an operation condition signal, and a passage for introducing fuel adsorbed by a canister into a suction pipe together with fresh air according to a drive signal. A purge valve that opens and closes, a means for determining whether or not the purge condition is the lean condition, a means for opening the purge valve under the purge condition based on a result of the determination, and whether the purging is being performed and the lean condition is satisfied. Means for judging whether the target air-fuel ratio is corrected to a lean side during purging and under the lean condition based on the judgment result, and calculating a target air-fuel ratio. It is means for calculating a fuel injection amount of the basic injection amount in accordance with the correction to the lean condition, characterized by providing a device and to supply feed fuel of the injection amount Evaporative fuel treatment system for engines. 5. A sensor for detecting an oxygen concentration in 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 stoichiometric air-fuel ratio under non-lean conditions and air-fuel ratio feedback conditions. A purge valve that adjusts the flow rate of the passage that introduces the fuel adsorbed by the canister into the intake pipe together with fresh air according to the drive signal, and a basic value of the target air-fuel ratio on the lean side under the lean condition as an operation condition signal. Means for calculating the lean condition as a first purge condition, and determining whether the lean condition is a purge condition during air-fuel ratio feedback correction and as a second purge condition during a low load after completion of engine warm-up. Means for calculating the degree of opening of the purge valve from the fuel concentration in the purge gas under purge conditions based on the determination result. Means for outputting a drive signal corresponding 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 is being performed, and the air-fuel ratio feedback correction is being performed; Means for calculating a fuel concentration in the purge gas based on the air-fuel ratio feedback correction coefficient and the purge valve opening during the purging under the second purge condition, the non-lean condition, and the air-fuel ratio feedback correction based on the result. Means for judging whether the purging is being performed under the first purge condition and whether the fuel is in the lean condition. The fuel contained in the purge gas is being purged under the first purging condition and being in the lean condition based on the judgment result. Means for calculating the fuel ratio of the purge gas based on the concentration and the basic value of the target air-fuel ratio; Means for calculating an air-fuel ratio correction amount which becomes smaller as the ratio becomes larger in accordance with the ratio; means for calculating a target air-fuel ratio by correcting the basic value of the target air-fuel ratio to the lean side with the air-fuel ratio correction amount; During the purging under the purge condition and the lean condition, the basic injection amount corresponding to the operating condition signal is corrected by the target air-fuel ratio and the air-fuel ratio feedback correction coefficient under the non-lean condition and the air-fuel ratio feedback condition. means for calculating a fuel injection amount, fuel vapor treatment system for an engine, characterized in that a device and to supply feed fuel of the injection amount. 6. A basic E according to an operation condition signal under an EGR condition.
Means for calculating a GR valve opening degree, a sensor for detecting oxygen concentration in exhaust gas, means for calculating an air-fuel ratio feedback correction coefficient based on the sensor output so that the exhaust air-fuel ratio matches the stoichiometric air-fuel ratio, means for calculating a fuel injection amount of the basic injection amount in accordance with the operating condition signal with the feedback correction coefficient correcting the, the device for supply supplying a fuel of the injection amount, together with fresh air and fuel adsorbed to a canister intake A purge valve for adjusting a flow rate of a passage introduced into the pipe in accordance with a drive signal; a means for determining whether or not the EGR and the air-fuel ratio feedback correction are performed under a purge condition; Means for calculating the purge valve opening from the fuel concentration in the purge gas under the conditions; Means for outputting to a purge valve; means for judging whether the purging is being performed and the air-fuel ratio feedback correction is being performed and the EGR is being performed; Means for calculating the fuel concentration in the purge gas based on the fuel ratio feedback correction coefficient and the purge valve opening; and A means for calculating a fuel ratio of the purge gas based on the feedback correction coefficient; a means for calculating an opening correction amount which becomes larger as the fuel ratio of the purge gas increases, and opening the basic EGR valve with the opening correction amount Means for calculating the EGR valve opening by increasing the degree of increase, Means for outputting a signal corresponding to the opening degree of the EGR valve to the EGR valve.