JP2760175B2 - Evaporative fuel treatment system for internal combustion engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporative fuel processing apparatus for an internal combustion engine, and more particularly to a communication path for directly communicating a fuel tank with an intake pipe of an internal combustion engine (engine) to convey evaporative fuel to a combustion chamber. The present invention relates to an evaporative fuel processing apparatus for burning fuel.

[0002]

2. Description of the Related Art Conventionally, a purge passage is provided as a communication passage that directly communicates from a fuel tank of a vehicle to an intake pipe of an engine.
2. Description of the Related Art There is an evaporative fuel processing device that directly sends evaporative fuel (vapor) generated in a fuel tank to an intake pipe and burns the vapor in a combustion chamber. Further, there is known an evaporative fuel processing apparatus having a means for detecting a vapor generation amount and a subtraction means for reducing an original fuel injection amount by a fuel injection valve based on the detected vapor generation amount (for example, Japanese Patent Application Laid-Open No. H10-163873). Sho 62-135625
No.). The evaporative fuel processing apparatus disclosed in this publication focuses on the correlation between the amount of vapor generated from the fuel tank and the engine cooling water temperature, intake air temperature, and fuel temperature. Alternatively, a vapor generation amount is detected from the fuel temperature, and a start-time correction coefficient for reducing and correcting the original fuel injection amount when the engine is started is calculated from the vapor generation amount. In particular, when the engine is started, the vapor fills the intake pipe and the air-fuel ratio is extremely rich, so that the startability of the engine is deteriorated.
The processing device disclosed above is configured to optimally control the fuel injection amount at the time of engine start by the start-time correction coefficient, so that the air-fuel ratio at the time of engine start can be optimally controlled. Startability can be improved.

[0003]

In the above-mentioned conventional evaporative fuel processing apparatus, the correction at the time of starting simply corrects the fuel injection amount from the amount of vapor detected from the coolant temperature, the intake air temperature or the fuel temperature. The coefficient is calculated. Generally, the vapor generated from a fuel tank is composed of a mixture of pure gasoline vapor generated from gasoline and air drawn into the tank. Although the gasoline vapor of this vapor makes the air-fuel ratio in the intake pipe rich, the air in the vapor acts to make the air-fuel ratio lean. Therefore, the increase or decrease of the air in the vapor has an opposite effect to the decrease correction for decreasing the original fuel injection amount of the fuel injection valve based on the amount of the vapor generated. That is, the air in the vapor acts in a direction to increase and correct the fuel injection amount. Therefore, the correction coefficient at the start in the conventional evaporative fuel processing apparatus that does not consider the amount of air in the vapor is inaccurate.

Further, the evaporative fuel processing apparatus of the above example mainly corrects the fuel injection amount at the time of starting the engine as described above, and changes in the various temperatures during normal operation of the engine and generation of vapor during normal operation. Since the amount of space in the fuel tank, which is one of the factors for increasing or decreasing the amount, is not taken into account, accurate correction of the fuel injection amount cannot be performed during normal operation of the engine.

Accordingly, the present invention has been made in view of the above problems, and provides a means for calculating the amount of gasoline vapor and the amount of air in vapor so that the fuel injection amount can be accurately corrected for the amount of vapor generated, and It is an object of the present invention to provide an evaporative fuel treatment system for an internal combustion engine that can optimally control the air-fuel ratio of the engine even in all operating states.

[0006]

FIG. 1 is a block diagram showing the principle of the present invention for achieving the above object. As shown in the figure, the present invention has a communication passage 14 for directly communicating a fuel tank 11 and an intake pipe 13 of an internal combustion engine 12 and detects a fuel evaporation amount of the evaporated fuel evaporated from the fuel tank 11. Evaporative fuel for an internal combustion engine having an amount detecting means 15 and a fuel correction amount calculating means 17 for correcting the fuel injection amount from a fuel injection valve 16 based on the fuel evaporation amount detected by the fuel evaporation amount detecting means 15 In the processing apparatus, the fuel tank 1
A gasoline vapor amount detecting means 18 for detecting a pure gasoline vapor amount of the evaporated fuel evaporating from 1, a fuel evaporating amount detected by the fuel evaporating amount detecting means 15, and a detection by the gasoline vapor amount detecting means 18. Air amount calculating means 19 for calculating the amount of air in the evaporated fuel from the obtained gasoline vapor amount, and the fuel correction amount calculating means 17 is provided with the gasoline vapor amount in the evaporated fuel and The fuel injection valve 16
This is a configuration for correcting the fuel injection amount from the engine.

[0007]

According to the present invention, the gasoline vapor amount detecting means 18 and the air amount calculating means 19 are provided to obtain the gasoline vapor amount and the air amount of the fuel vapor generated from the fuel tank 11 respectively. Then, when the distribution between the gasoline vapor amount and the air amount in the evaporated fuel is richer than the stoichiometric air-fuel ratio,
When the fuel correction calculating means 17 decreases the fuel injection amount from the fuel injection valve 16 and conversely, when the distribution between the gasoline vapor amount and the air amount of the evaporated fuel is leaner than the stoichiometric air-fuel ratio, The fuel injection amount from the fuel injection valve 16 is increased. Therefore, even if the distribution of the gasoline vapor amount and the air amount in the evaporated fuel changes in the operating state of the internal combustion engine,
Accordingly, the fuel injection amount from the fuel injection valve 16 can be accurately corrected.

[0008]

FIG. 2 shows a system configuration diagram of an embodiment of the present invention. This embodiment is an example in which the present invention is applied to a four-cylinder four-cycle spark ignition type internal combustion engine (engine) as the internal combustion engine 12 shown in FIG. 1, and is controlled by a microcomputer 21 and an engine control computer (ECU) 22, which will be described later.

In FIG. 2, reference numeral 23 denotes a fuel tank (corresponding to the fuel tank 11). The fuel tank 23 has a fuel temperature sensor 24 for measuring a fuel temperature, and a remaining fuel amount in the fuel tank 23. Is installed. Fuel temperature sensor 24,
The signals from the fuel remaining amount sensor 25 are output to the microcomputer 21.

Reference numeral 41 denotes an intake pipe of the engine 40 (corresponding to the intake pipe 13), and an air cleaner (not shown) is provided at an opposite end of the combustion chamber 40a. In the intake pipe 41, from the upstream side where the air cleaner is provided,
An air flow meter 42, a throttle valve 43, a surge tank 44, and a fuel injection valve 45 are provided. The air flow meter 42 detects the amount of air taken into the intake pipe 41,
This detection signal is output to the microcomputer 21. A fuel circulation line 47 is provided between the fuel injection valve 45 and the fuel tank 23, and the fuel in the fuel tank 23 is constantly circulated by the fuel circulation pump 46. The fuel injection valve 45 injects a fixed amount of fuel into the intake pipe 41 only during a time instructed by an injection command from the ECU 22. Therefore, the time during which fuel injection is performed in the fuel injection valve 45 directly corresponds to the fuel injection amount.

[0011] Evaporated fuel (vapor) from the fuel tank 23
The line 26 includes a canister line 26 b that passes through the tank pressure control valve 27 to the canister 30, and a vacuum switching valve (VSV) from the fuel tank 23.
And a direct line 26a (corresponding to the communication path 14) which leads to an engine 40 (corresponding to the internal combustion engine 12) via an electromagnetic valve 31 referred to as the internal combustion engine 12.

The canister 30 is filled with an adsorbent such as activated carbon, and an air inlet 30a is provided below the adsorbent. A purge line 33 is provided from the canister 30 to communicate with the engine 40 via another solenoid valve 32. The tank internal pressure control valve 27 prevents the vapor from flowing from the fuel tank 23 toward the canister 30 during engine operation by setting the opening pressure higher than the atmospheric pressure. The solenoid valve 31 has its valve opening adjusted by a control signal from the microcomputer 21 as will be described later.
Adjust the vapor flow rate to 1.

The direct line 26a through which the vapor from the fuel tank 23 is conveyed, and the purge line 3
3 is connected to the surge tank 44 in the present embodiment, but the connection portion may be any portion on the intake pipe 41.

As is well known, the vapor generated in the fuel tank 23 while the engine is stopped is discharged to the canister line 26b.
And is adsorbed by the activated carbon in the canister 30 to prevent release to the atmosphere. Then, at the time of idling operation immediately after the start of the engine, air is introduced from the atmosphere introduction port 30a of the canister 30 using the negative pressure in the surge tank 44 (the electromagnetic valve 32 is in an open state). The fuel adsorbed on the activated carbon is released. And
This fuel is drawn into the intake pipe 41 through the purge line 33 and is burned in the combustion chamber 40a.

During continuous operation of the engine 40, the temperature of the fuel rises by circulating through the fuel circulation line 47 through the fuel injection valve 45 where the temperature of the fuel becomes high. The vapor generated as the fuel temperature rises is reduced by the surge valve 4 when the solenoid valve 31 is opened appropriately.
Utilizing the negative pressure in 4, the air is sucked into the intake pipe 41 through the direct line 26a and burned as described above.

The microcomputer 21 for controlling the operation of each section having the above-described configuration has a hardware configuration as shown in FIG. 2, the same components as those in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted.

In FIG. 3, a microcomputer 21
Denotes a central processing unit (CPU) 50, a read-only memory (ROM) 51 storing a processing program, and a random access memory (RA) used as a work area.
M) 52, a backup RAM 53 that retains data even after the engine is stopped, an input interface circuit 54, an A / D converter 56 with a multiplexer, an output interface circuit 55, etc., which are interconnected via a bus 57. Have been.

The A / D converter 56 is a fuel temperature sensor 2
4, a fuel remaining amount detection signal from the fuel remaining amount sensor 25, an intake air amount detecting signal from the air flow meter 42, etc. are sequentially switched through the input interface circuit 54 and periodically taken in.
The digital data is converted and sequentially transmitted to the bus 57. The output interface circuit 55 receives the signal processed by the CPU 50 via a bus 57 and outputs the signal to the solenoid valve 31 and the ECU.
22 to control them. The ECU 22 controls the fuel injection time of the fuel injection valve 45 and the solenoid valve 32 based on the input signal. In the idle state after the engine is started, the solenoid valve 32 controls the valve opening degree substantially proportional to the intake air amount of the engine 40. The control of the fuel injection time of the fuel injection valve 45 will be described later in detail.

FIG. 4 shows the microcomputer 2 having the above configuration.
FIG. 2 is a block diagram showing the configuration of the processing content in FIG.

The configuration of the processing contents by the microcomputer 21 includes a solenoid valve flow rate calculating device 60 (corresponding to the fuel evaporation amount detecting means 15), a solenoid valve driving circuit 70, and a fuel correction amount calculating device 80 (the gasoline vapor amount). Detecting means 18,
(Corresponding to the air amount calculating means 19 and the fuel correction amount calculating means 17). The amount of vapor generation is estimated by the solenoid valve flow rate calculation device 60, and the opening degree of the electromagnetic valve 31 corresponding to the amount of vapor generation is determined. The determined valve opening is transmitted to the solenoid valve drive circuit 70, and the solenoid valve 31 is opened such that the flow rate at the solenoid valve 31 becomes the target flow rate at which the generated vapor flows without excess or deficiency. On the other hand, the fuel correction amount calculating device 80 calculates the amount of excess fuel sucked into the intake pipe 41 by the vapor from the flow rate at the solenoid valve 31 as described later in detail, and calculates the fuel injection valve calculated by the ECU 22. 45
Correction of the original fuel injection time.

The CPU 50 in the microcomputer 21 having the above-described structure, according to the program stored in the ROM 51, has the above-described fuel evaporation amount detecting means 15, gasoline vapor amount detecting means 18, air amount calculating means 19, and fuel correction amount calculating means. 17 is realized.

First, the processing for calculating the target flow rate of the solenoid valve 31 for realizing the fuel evaporation amount detecting means 15 will be described with reference to the flowchart shown in FIG. The target flow rate is obtained by estimating the amount of vapor containing gasoline vapor accompanying the temperature rise in the fuel tank 23, and setting this generated amount as the target flow rate. In this manner, all the vapor generated from the fuel tank 23 can be sucked into the engine 40, and conversely, new vapor is prevented from being generated from the fuel tank 23 due to the negative pressure of the intake pipe 41. it can.

FIG. 5 shows a flowchart of a solenoid valve flow rate calculation routine for realizing the fuel evaporation amount detecting means 15. When the routine 100 shown in FIG. 3 is started by interruption every period Δtc seconds, first, the current fuel temperature Tn is processed by a signal from the fuel temperature sensor 24 and held.
It is read from M52 (step 101). Next, ROM
The vapor generation amount TQn at the fuel temperature Tn read in step 101 is calculated by interpolation from the vapor generation amount map 200 shown in FIG. 9 stored in advance in step 51 (step 102). This map 200 shows the fuel temperature T
The relationship between a fuel volume per unit volume of the fuel tank 23 and a cumulative vapor generation amount TQ from −20 ° C. per liter to a fuel temperature T ° C., which will be described later, is obtained by an experiment. Therefore, the unit of the vapor generation amount TQn is (liter /
Liters).

Next, the fuel temperature T at the time of execution of the previous routine
A vapor generation amount QL generated when the fuel temperature rises from ₀ to the current fuel temperature Tn is determined. This vapor generation amount Q
L is the difference between the previous vapor generation amount TQ ₀ stored in the previous routine and the current vapor generation amount TQn, that is,
It can be calculated by QL = TQn-TQ ₀ (step 103).

Next, by subtracting the fuel remaining amount Vs obtained from the fuel remaining amount sensor 25 from the tank capacity Vt,
The current tank space volume Va is calculated (see FIG. 2, step 104). Vapor generation amount obtained in step 103 QL is a vapor generation amount per tank space volume Va1 liters when the fuel temperature increases from T ₀ to Tn.
Therefore, the target flow rate Q per unit time (1 sec) at the time of execution of the current routine is obtained from QL × Va / Δtc.
t (liter / sec) can be obtained (step 1)
05).

Next, for the time of next execution of the routine, replaces the vapor generation amount TQn at current fuel temperature Tn in TQ ₀ (step 106). Then, the new TQ ₀ and the target flow rate Qt obtained in step 105 are newly added to RA.
This routine is stored in M52 (step 107).
00 is ended (step 108).

The map 20 referred to in step 102
0, as described above, the fuel temperature T and the tank space volume V
a Fuel temperature per liter -20 ° C to fuel temperature T ° C
Although the relationship with the accumulated vapor generation amount TQ up to this is stored, it may be calculated by the following equation (1) instead.

[0028]

(Equation 1)

R: gas constant Pa: pressure of fuel tank (≒ atmospheric pressure) Pg (T): gasoline vapor pressure at fuel temperature T (° K) Gasoline vapor pressure is an approximate expression by the following equation (2) Ask by

[0030]

(Equation 2)

Here, Tb: boiling point (55 ° C.) Tc: fuel temperature (° C.) FIG. 6 shows a routine for determining the opening of the solenoid valve 31. This routine 110 is similar to the routine 100 in FIG.
This is executed every Δtd seconds in the electromagnetic valve flow rate calculation device 60 shown by. First, the intake air amount Qsn (liter / rev)
Is read from the RAM 52 in which the signal from the air flow meter 42 is processed and held (step 11).
1). Next, using the intake air amount Qs as a variable in advance, the solenoid valve 3
The maximum flow rate Qn of the solenoid valve 31 with respect to the intake air amount Qsn read in step 111 is obtained from the map 210 shown in FIG. 10 which stores the flow rate Q (maximum flow rate) of the solenoid valve 31 when the valve 1 is fully opened ( Step 11
2). Originally, in order to improve the accuracy, the pressure difference between the upstream and downstream of the solenoid valve 31 should be used as a variable. However, the pressure in the intake pipe 41 is represented by the intake air amount obtained from the air flow meter 42, and the fuel tank 23 Since the value on the side is close to the atmospheric pressure, there is no practical problem even if the maximum flow rate of the solenoid valve 31 is obtained by substituting the intake air amount as a variable. Therefore, in this embodiment, the map 210 shown in FIG. 10 is used.

Next, the valve opening α of the solenoid valve 31 is determined based on the ratio between the maximum flow rate Qn obtained in step 112 and the target flow rate Qt obtained in the routine 100 (step 1).
13), terminates this routine 110 (step 11)
4). Then, the opening α is output to the solenoid valve driving circuit 70 shown in FIG. 4, and the valve opening of the solenoid valve 31 is set to the desired opening α. The valve opening α is actually controlled by the pulse width of the pulse signal. That is, the opening time (corresponding to the pulse width) of the solenoid valve 31 that repeats opening and closing by a pulse signal.
Is increased or decreased to change the valve opening. By doing so, the accuracy of the flow rate corresponding to the valve opening of the solenoid valve 31 is improved.

Next, the gasoline vapor amount detecting means 18,
The estimation logic of the fuel correction amount in the fuel correction amount calculation device 80 that realizes the air amount calculation means 19 and the fuel correction amount calculation means 17 will be described with reference to the flowchart shown in FIG.

The concept of the fuel correction is to estimate the amount of pure gasoline vapor and the amount of air contained in the vapor from the fuel tank 23, respectively, and to determine the ratio thereof, that is, the mixture ratio on the richer side than the stoichiometric air-fuel ratio. In some cases, reduce the fuel injection amount,
Conversely, when the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, the fuel injection amount is increased.

FIG. 7 shows a flowchart of a fuel correction amount calculation routine executed in the fuel correction amount calculation device 80. The routine 120 has the same cycle Δ as the routine 100.
Processing is performed in tc seconds. First, the current fuel temperature Tn
Is read from the RAM 52 as in the routine 100 (step 121). Next, a gasoline vapor generation amount Qtn at the fuel temperature Tn read in step 121 is calculated by interpolation from a gasoline vapor generation amount map 220 shown in FIG. 11 stored in the ROM 51 in advance (step 122). The map 220 is obtained by an experiment to determine the relationship between the fuel temperature T and the integrated gasoline vapor generation amount Qt from the fuel temperature of −20 ° C. per 1 liter of the tank space Va to the fuel temperature T ° C.

Next, the fuel temperature T at the time of execution of the previous routine
_The gasoline vapor generation amount Qgv generated when the fuel temperature rises from ₀ to the current fuel temperature Tn is determined. The gasoline vapor emissions Qgv the difference between routines 100 similarly to the previous gasoline vapor emissions Qt ₀ stored at the time of the previous execution of the routine, the current gasoline vapor emissions Qtn, i.e., Qgv = Qtn-Qt ₀ Can be calculated (step 123).

The gasoline vapor emissions Qgv obtained in step 123 is a gasoline vapor emission per tank space volume Va1 liters when the fuel temperature increases from T ₀ to Tn. Accordingly, the gasoline vapor generation amount Qg (liter / sec) per unit time (1 sec) at the time of execution of the current routine can be obtained from Qgv × Va / Δtc (step 124). As described above, in the steps up to this point, the gasoline vapor generation amount Qg in the vapor generated by the same method as the routine 100 described above.
And the gasoline vapor amount detecting means 18 is realized.

Next, by subtracting the gasoline vapor generation amount Qg from the vapor generation amount Qt per unit time obtained in the routine 100, the air generation amount Qa (liter / sec) per unit time in the vapor is obtained. (Step 125). Therefore, the air amount calculation means 19 is realized by this step 125. Next, the fuel injection amount conversion values Tg and Ta are obtained by multiplying the gasoline vapor generation amount Qg and the air generation amount Qa by the coefficients Kg and Kp, respectively (step 126). The coefficient Kg is a conversion constant for converting the amount of gasoline vapor expressed in liters into a substantial fuel injection amount (fuel injection time) corresponding to this gasoline amount, and the coefficient Kp is generated air. This is a conversion constant for converting the amount into a fuel injection amount (fuel injection time) that is a stoichiometric air-fuel ratio.

Next, the same value Tg is calculated from the fuel injection amount conversion value Ta.
Is subtracted to calculate an injection amount (injection time) correction value ΔTp (step 127). Here, when the relationship of Ta> Tg, that is, ΔTp is positive, it indicates that the mixture ratio of gasoline vapor and air in the vapor generation amount Qt is leaner than the stoichiometric air-fuel ratio. <Tg relationship, ie ΔT
When p becomes negative, it indicates that the mixture ratio of gasoline vapor and air in the vapor generation amount Qt is richer than the stoichiometric air-fuel ratio. When Ta = Tg, the vapor has just reached the stoichiometric air-fuel ratio, and ΔTp = 0.

As described above, the above steps 126 and 127 are performed.
Thus, the injection amount (injection time) correction value ΔTp can be obtained, and the fuel correction amount calculating means 17 is realized.

Next, for the next execution of the routine, the gasoline vapor generation amount Qtn at the current fuel temperature Tn is set to Qt.
_Replace with ₀ (step 128). And the new Q
t ₀ and the injection amount correction value ΔTp obtained in step 127 are newly stored in the RAM 52 (step 129), and the routine 120 is terminated (step 130).

As described above, the fuel correction amount calculation routine 12
0, the air generation amount Qa is calculated from the vapor generation amount Qt and the gasoline vapor generation amount Qg, and an injection amount correction value ΔTp for correcting the mixture ratio of gasoline vapor and air in the vapor to the stoichiometric air-fuel ratio is obtained. Can be.

The map 220 in step 122 includes:
As described above, the fuel temperature T and the tank space volume Va1
The relationship between the accumulated gasoline vapor generation amount Qt from the fuel temperature of −20 ° C. per liter to the fuel temperature T ° C. is stored. Alternatively, the relationship may be calculated by the following equation (3).

[0044]

(Equation 3)

[0045] However, Pa: pressure in the fuel tank (≒ atmospheric pressure) Pg (Tn): gasoline vapor pressure when the fuel temperature Tn (° K) QL: between fuel temperature Tn～T ₀ obtained by the formula (1) The accumulated vapor generation amount per liter of tank space volume Va is sent to the engine control computer (ECU) 22 in the injection amount correction value ΔTp obtained in the above step 127. FIG. 8 shows an injection amount calculation routine 1 processed in the ECU 22.
40 shows a flowchart of 40.

In FIG. 8, the air flow meter 42
Is multiplied by the conversion coefficient Kp used in step 126 of the fuel correction amount calculation routine 120 to obtain the basic injection amount T by the fuel injection valve 45.
Calculate p (step 141). This basic injection amount Tp
Is a fuel injection amount for setting the stoichiometric air-fuel ratio with respect to the intake air amount Qs when there is no vapor suction into the intake pipe 41.

Then, the basic injection amount Tp is corrected by adding the injection amount correction value ΔTp obtained in the routine 120 to the basic injection amount Tp obtained in the above step 141, so that the fuel injection valve 45 actually outputs the correction value. The fuel injection amount Tp 'to be injected is obtained (step 142), and this routine 140
Is ended (step 143).

Since a pulse signal (drive signal) having a pulse width of the fuel injection amount Tp 'is supplied to the fuel injection valve 45, the actual fuel injection amount (fuel injection time) Tp' is Lean side of the stoichiometric air-fuel ratio (Δ
When Tp is positive, the basic injection amount (basic injection time) Tp is increased, and when it is rich (ΔTp is negative), the basic injection amount (basic injection time) Tp is controlled to an optimal state so as to decrease. .

As described above, according to this embodiment, the gasoline vapor amount detecting means 18, the air amount calculating means 19, and the fuel correcting amount calculating means 17 are executed by the fuel correction amount calculation routine 120.
Is realized, and the injection amount correction value ΔTp for correcting the mixture ratio of gasoline vapor and air in the vapor to the stoichiometric air-fuel ratio can be obtained. Accordingly, in a configuration in which vapor is directly drawn into the intake pipe 41 from the fuel tank 23 and burned, even if the distribution of the gasoline vapor amount and the air amount in the vapor generated from the fuel tank 23 changes, the injection amount correction is performed. The fuel injection amount by the fuel injection valve is appropriately increased or decreased by the value ΔTp, so that the air-fuel ratio of the engine can be optimally controlled in all operating states of the engine.

Further, high temperature gasoline vapor during normal operation of the engine contains a large amount of high boiling point components in gasoline, causing deterioration of the canister 30. However, as in the present embodiment, by performing the optimal air-fuel ratio control so that the vapor does not pass through the canister 30 during the normal operation of the engine, deterioration of the canister 30 can be prevented.

It should be noted that the present invention is not limited to the above embodiment, and the direct line 26 from the fuel tank 23 is
A configuration in which a flow rate sensor is simply provided on a to directly detect the amount of vapor generated, and the amount of gasoline vapor generated is experimentally obtained from the fuel temperature as in the above embodiment, and the amount of air in the vapor is obtained from the difference between the two. Alternatively, the flow rate sensor for detecting the amount of generated vapor and the concentration sensor for detecting the gasoline concentration in the vapor are provided, and the gasoline vapor amount and the air amount in the vapor are obtained based on the signals of the two. It may be. In these cases, it is needless to say that the same effects as those of the above embodiment can be obtained.

[0052]

As described above, according to the present invention, the gasoline vapor amount detecting means and the air amount calculating means respectively obtain the gasoline vapor amount and the air amount of the generated amount of the evaporated fuel, and Even when the fuel is sucked into the intake pipe, the fuel correction calculation means controls the fuel injection amount from the fuel injection valve to obtain the stoichiometric air-fuel ratio. Even if the distribution between the fuel and the air amount changes, the fuel injection amount from the fuel injection valve can be accurately corrected in accordance with the change. Therefore, the air-fuel ratio of the internal combustion engine can be optimally controlled even in all operating states of the internal combustion engine.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a system configuration diagram of an embodiment of the present invention.

FIG. 3 is a diagram illustrating a hardware configuration of the microcomputer illustrated in FIG. 2;

FIG. 4 is a block diagram showing a configuration of processing contents in a microcomputer 21 shown in FIG.

FIG. 5 is a flowchart illustrating a solenoid valve flow rate calculation routine.

FIG. 6 is a flowchart showing an electromagnetic valve opening calculation routine.

FIG. 7 is a flowchart illustrating a fuel correction amount calculation routine.

FIG. 8 is a flowchart illustrating an injection amount calculation routine.

FIG. 9 is a diagram showing a map of a relationship between a fuel temperature and a vapor generation amount per liter of tank space amount.

FIG. 10 is a diagram showing a map of a relationship between an intake air amount and a maximum flow rate when the electromagnetic valve is fully opened.

FIG. 11 is a diagram showing a map of a relationship between a fuel temperature and an amount of gasoline vapor generated per liter of tank space.

[Explanation of symbols]

 11, 23 Fuel tank 12, 40 Internal combustion engine (engine) 13, 41 Intake pipe 14 Communication path 15 Fuel evaporation amount detecting means 16, 45 Fuel injection valve 17 Fuel correction amount calculating means 18 Gasoline vapor amount detecting means 19 Air amount calculating means 21 Microcomputer 22 Engine Control Computer (ECU) 24 Fuel Temperature Sensor 25 Fuel Remaining Sensor 31, 32 Solenoid Valve 42 Air Flow Meter

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tohru Kisokoro 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-4-76239 (JP, A) JP-A-63- 186955 (JP, A) JP-A-59-46338 (JP, A) JP-A-5-52139 (JP, A) JP-A-5-33733 (JP, A) JP-A-62-135625 (JP, A) JP-A 1-148043 (JP, U) JP-A 1-148767 (JP, U) (58) Fields studied (Int. Cl. ⁶ , DB name) F02D 41/00-41/40 F02M 25/08 301

Claims (1)

(57) [Claims] 1. A fuel evaporation amount detecting means having a communication path for directly communicating a fuel tank with an intake pipe of an internal combustion engine, and detecting an evaporation amount of evaporated fuel evaporating from the fuel tank. A fuel correction amount calculating means for correcting the fuel injection amount from the fuel injection valve based on the fuel evaporation amount detected by the means. A gasoline vapor amount detecting means for detecting a pure gasoline vapor amount, a fuel evaporating amount detected by the fuel evaporating amount detecting means, and a gasoline vapor amount detected by the gasoline vapor amount detecting means. Air amount calculating means for calculating the air amount of the fuel gas, and the fuel correction amount calculating means comprises the gasoline vapor amount and the air amount of the evaporated fuel. A fuel injection amount from the fuel injection valve is corrected by the distribution of the fuel injection valve.