JPH1182189A - Fuel supply system for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress exhaust of unburnt HC at the time of low temperature start-up of an engine. SOLUTION: A main injector 11 for injecting and supplying fuel in a fuel tank 13 to an engine body 1, and a sub-injector 12 for injecting and supplying fuel in a liquefied fuel recovery container 16 to the engine body 1, are disposed at an intake port of an engine. A canister 26 is connected to the fuel tank 13 through a first evaporation passage 24, and the liquefied fuel recovery container 16 is disposed at an intermediate part of the evaporation passage 24. The liquefied fuel recover container 16 stores evaporated fuel discharged from the fuel tank 13 and liquefied in the first evaporation plassage 24. This stored fuel contains components having low boiling points and easily vaporized, at a large rate compared with fuel in the fuel tank 13. In the low temperature start-up state of the engine and at the time of the fuel quantity in the liquiefied fuel recovery contained 16 exceeding the specified level, the ECU 40 injects to supply liquefied fuel stored in the container 16, to the engine from the sub- injector 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for an engine, and more particularly to a fuel supply device for an engine, in which fuel vapor generated in a fuel tank is once adsorbed by a canister, and the fuel vapor adsorbed by the canister is discharged to an engine intake system. The present invention relates to a fuel supply device for an engine that is designed to burn in the engine.

[0002]

2. Description of the Related Art Conventionally, a gasoline engine for an automobile is provided with an evaporative fuel discharge mechanism for temporarily adsorbing evaporative fuel (evaporative gas) generated in a fuel tank to a canister and discharging the adsorbed evaporative fuel to an engine intake system. ing.
In such a case, when fuel evaporates in the fuel tank due to an increase in outside air temperature or the like when the engine is stopped or operating, the tank internal pressure increases and the fuel vapor is discharged toward the canister. Then, the evaporated fuel adsorbed by the canister is released into the engine intake system by opening and closing a purge valve provided in the middle of the purge pipe, and is provided to the engine for combustion together with the fuel injected by the injector.

[0003]

The conventional fuel supply system has the following problems. In other words, particularly during a cold start of the engine, the fuel injected by the injector tends to adhere to the low-temperature cylinder wall during the intake stroke immediately before combustion, and the deposited fuel becomes unburned HC together with the exhaust gas during the exhaust stroke. Emitted from the engine. In addition, since the temperature of the catalyst has not risen to the activation temperature immediately after the start of the engine, unburned HC may be discharged to the atmosphere without being purified.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an engine fuel supply device capable of suppressing the emission of unburned HC at the time of low temperature starting of the engine. To provide.

[0005]

According to the first aspect of the present invention, the liquefied fuel recovery container is provided with a fuel vapor liquefied in a communication passage connecting the fuel tank and the canister, of the fuel vapor discharged from the fuel tank. To store. The fuel amount detecting means detects a fuel amount in the liquefied fuel recovery container. The first fuel supply means supplies the fuel in the fuel tank to the engine mainly during normal operation. Further, the second fuel supply means is provided when the detected amount of fuel in the liquefied fuel recovery container exceeds a predetermined level under a low-temperature start state of the engine and
The liquefied fuel stored in the container is supplied to the engine.

[0006] In short, the fuel stored in the liquefied fuel recovery container is obtained by liquefying and recovering the fuel once evaporated in the fuel tank, and has a lower boiling point than the fuel in the fuel tank and is easily vaporized. The ratio is large. Therefore, when the fuel is supplied using this fuel, the amount of fuel adhering to the cylinder wall surface (cylinder wet amount) is reduced because the component having a high boiling point and adhering to the cylinder wall surface without vaporization is small. In other words, the emission of unburned HC in the exhaust stroke can be significantly reduced as compared with the existing device. As a result, the object of the present invention, such as suppressing the emission of unburned HC at the time of starting the engine at a low temperature, is achieved.

The invention of claim 1 can be embodied as follows. That is, in the invention described in claim 2, the first
The fuel supply means drives the main injector to inject and supply the fuel in the fuel tank to the engine, and the second fuel supply means drives the sub-injector to supply the liquefied fuel in the liquefied fuel recovery container to the engine. Injection is to be supplied. In this case, by properly using the main injector and the sub-injector, the fuel in the liquefied fuel recovery container can be suitably injected and supplied to the engine.

According to the third aspect of the invention, while adjusting the fuel supply amount by the first fuel supply means and the fuel supply amount by the second fuel supply means at a predetermined ratio,
The two fuel supply means are used in combination. In this case, as described in claim 4, the ratio between the amount of fuel supplied by the first fuel supply unit and the amount of fuel supplied by the second fuel supply unit is determined in the detected liquefied fuel recovery container. It may be determined according to the fuel amount.

According to the third and fourth aspects of the present invention, even if the amount of fuel in the liquefied fuel recovery container is relatively small, the fuel can be effectively used without hindering the operation of the engine. In such a case, even when the amount of fuel used from the liquefied fuel recovery container is small, only the fuel in the fuel tank is supplied to the engine (when the entire supply amount is the fuel in the tank).
The effect of reducing the cylinder wet amount can be obtained as compared to

[0010] In the invention described in claim 5, the second fuel supply means supplies the liquefied fuel in the liquefied fuel recovery container to the engine until the activation of the catalytic converter is determined. In other words, it takes about 30 seconds for the cold catalytic converter to be activated and exhibit the original purifying function of the catalyst. Until that time, the fuel in the liquefied fuel recovery container is injected. After the activation of the catalyst, even if unburned HC due to cylinder wet is discharged from the engine, the unburned HC is purified by the catalyst, so that air pollution can be reduced without using the fuel in the liquefied fuel recovery container. I will not invite you.

[0011] In the invention described in claim 6, the liquefied fuel recovery container is provided at a position as close as possible to the canister. In this case, a passage (pipe) connecting the fuel tank and the liquefied fuel recovery container becomes longer, and liquefaction of the evaporated fuel is promoted by heat exchange in the passage. Therefore, the fuel can be efficiently recovered in the liquefied fuel recovery container.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a fuel injection system for a gasoline engine will be described below with reference to the drawings.

The fuel injection system for an engine according to the present embodiment is provided with an evaporative fuel release mechanism for temporarily adsorbing the evaporative fuel generated in the fuel tank to the canister and discharging the evaporative fuel adsorbed to the canister to the engine intake system. . The fuel released to the engine intake system is burned in the engine combustion chamber together with the fuel injected by the injector. In addition, the system includes a liquefied fuel recovery container between the fuel tank and the canister for liquefying and recovering the evaporated fuel generated in the fuel tank. In such a case, the fuel in the fuel tank is injected and supplied to the engine using the existing main injector, while the liquefied fuel in the liquefied fuel recovery container is injected and supplied to the engine using the newly installed sub-injector.
Each of these injectors is driven by an electronic control unit (hereinafter referred to as E).
CU). In particular, when the engine is started at a low temperature, the sub-injector is driven to supply the fuel in the liquefied fuel recovery container to the engine, thereby improving the exhaust emission at the time of starting the engine. Hereinafter, the detailed configuration will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an outline of a fuel injection system according to the present embodiment. In FIG.
An intake pipe 2 and an exhaust pipe 3 are connected to the engine body 1. The intake pipe 2 is provided with a throttle valve 4 linked to an accelerator pedal (not shown). Engine body 1
A piston 6 which reciprocates in the vertical direction in the figure is disposed in the cylinder 5, and the piston 6 is connected to a crankshaft (not shown) via a connecting rod 7. A combustion chamber 8 is formed above the piston 6, and the combustion chamber 8
The intake pipe 2 through an intake valve 9 and an exhaust valve 10;
And the exhaust pipe 3.

A main injector 11 for injecting and supplying the fuel in the fuel tank 13 to the engine main body 1 (combustion chamber 8) is disposed at an intake port of the intake pipe 2. Liquefied fuel recovery container 1
A sub-injector 12 for injecting and supplying the fuel in the engine 6 to the engine body 1 (combustion chamber 8) is provided. After the fuel in the fuel tank 13 is pumped up by the fuel pump 14 and adjusted in pressure by the pressure regulator 15,
It is supplied to the main injector 11. The fuel in the liquefied fuel recovery container 16 is supplied to a pressure regulator 19 via a fuel pipe 18 by a fuel pump 17. Then, after the pressure is adjusted by the pressure regulator 19, the pressure is supplied to the sub-injector 12. Here, a check valve 20 for preventing a backflow of fuel from the fuel pipe 18 into the liquefied fuel recovery container 16 is provided at an end of the fuel pipe 18 on the pump side.

The exhaust pipe 3 is provided with a three-way catalyst 21 for purifying CO (carbon monoxide), HC (hydrocarbon), and NOx (nitrogen oxide) in the exhaust gas. Further, the three-way catalyst 21 is provided with a catalyst temperature sensor 22 for detecting a catalyst temperature. An output signal of the catalyst temperature sensor 22 is appropriately taken into the ECU 40, and the degree of catalyst activation is determined from the output signal.

Next, the configuration of the evaporated fuel release mechanism will be described. A canister 26 is connected to the fuel tank 13 via a first evaporation passage 24 and a second evaporation passage 25. Activated carbon as an adsorbent is stored in the canister 26, and evaporated fuel (evaporative gas) generated in the fuel tank 13 during operation and stop of the engine is adsorbed by the canister 26 as needed. The connection between the first evaporation passage 24 and the canister 26 includes a fuel tank 13.
A tank internal pressure adjusting valve 27 for adjusting the internal pressure (tank internal pressure) and preventing damage to the tank 13 is provided. The canister 26 is provided with an atmosphere port 26a for introducing outside air.

A fuel tank 13 is provided in the second evaporation passage 25.
A fuel supply valve 28 that allows only the passage of the evaporated fuel toward the canister 26 is provided. This refueling valve 28 is
When fuel is supplied to the fuel tank 13, the valve is opened by the evaporated fuel pushed out from the inside of the tank 13. In this case, when the fuel supply valve 28 is opened, the evaporated fuel is adsorbed to the canister 26 through the second evaporation passage 25, thereby preventing the leak of the evaporated fuel from the fuel tank 13 to the outside.

The fuel supply valve 28 may be an electromagnetically driven normally closed fuel supply valve. Specifically, when the tank cap 13a is opened, a refueling switch (not shown)
Is turned ON, and the refueling valve 28 is opened according to the ON signal. Thereby, the inside of the fuel tank 13 and the canister 26 are communicated with each other, and the fuel vapor is removed from the canister 26.
Is adsorbed.

One end of a purge passage 29 is connected to the canister 26, and the other end of the purge passage 29 is connected near the throttle valve 4 in the intake pipe 2. In this case, the evaporated fuel supplied from the canister 26 is discharged through the purge passage 29 to the collecting portion of the intake pipe 2 (the upstream portion of the intake manifold (not shown)). An electromagnetically driven purge valve 30 is disposed in the purge passage 29. The purge valve 30 is opened according to the operating state of the engine, and the purge flow rate is adjusted according to the degree of opening. That is, when the purge valve 30 is opened and the canister 26 and the intake pipe 2 communicate with each other via the purge passage 29, fresh air in the atmosphere is introduced into the canister 26 via the atmosphere port 26a.
At this time, the inside of the canister 26 is ventilated with fresh air, and the adsorbed fuel of the canister 26 is sent into the intake pipe 2 in accordance therewith, whereby the adsorption function of the canister 26 is restored.

Here, the liquefied fuel recovery container 16 is provided in the middle of the first evaporation passage 24. The liquefied fuel recovery container 16 collects and stores liquefied fuel in the first evaporative passage 24 out of the evaporated fuel generated in the fuel tank 13, and has a suction valve 31 and a discharge valve 3 at its upper part.
2 are provided.

The suction valve 31 has a role of opening the valve by its weight when a fixed amount of liquefied fuel is stored in the upper space of the liquefied fuel recovery container 16 and recovering the fuel in the container 16. Further, the discharge valve 32 is provided in the container 1 in order to minimize evaporation of the fuel in the liquefied fuel recovery container 16 and adsorption to the canister 26.
It has a role of maintaining the pressure in the container 6 and relieves steam when the pressure rises to near the pressure resistance of the container 16. FIG.
FIG. 3 is a cross-sectional view illustrating a configuration of the suction valve 31. As shown in the figure, the suction valve 31 has an elastically deformable umbrella valve 33 made of rubber, and when the periphery of the umbrella portion 33a is in contact with the container wall W, the suction valve 31 is closed. Will be retained. On the other hand, when the umbrella portion 33a is elastically deformed by the weight of the liquefied fuel as shown by the two-dot chain line in FIG. 3, the suction valve 31 is opened. On the other hand, since the discharge valve 32 has substantially the same configuration as the suction valve 31 except that the umbrella valve is turned upside down, the description thereof is omitted.

The liquefied fuel recovery container 16 is provided with a level gauge 34 for detecting the remaining amount of fuel in the liquefied fuel recovery container 16, and the output signal of the level gauge 34 is appropriately controlled by the ECU.
It is taken into 40.

The liquefied fuel recovery container 16 is preferably mounted at a position as far as possible from the fuel tank 13 and near the canister. This is to secure a section sufficient for the evaporated fuel to be liquefied by heat exchange in the first evaporation passage 24. However, when the entire length of the first evaporative passage 24 is shortened, such as when the fuel tank 13 and the canister 26 are both disposed at the rear of the vehicle, the inside of the first evaporative passage 24 (the fuel tank 13
For example, a configuration that promotes the liquefaction of the evaporated fuel may be added, for example, by providing a cooling device between the fuel cell and the liquefied fuel recovery container 16).

The ECU 40 includes a well-known input signal processing circuit,
It comprises an arithmetic circuit, an output signal processing circuit (drive circuit), a power supply circuit, and the like. Its main operation is to determine the fuel injection amount at each time according to the engine operating state, The “main injection” and the “sub-injection” by driving the sub-injector 12 are selectively performed.

Here, in the “main injection” by the main injector 11, the fuel in the fuel tank 13 is injected and supplied to the engine body 1, whereas the sub-injector 1
In “sub-injection” by 2, the fuel in the liquefied fuel recovery container 16 is injected and supplied to the engine body 1. Hereinafter, main differences between the main injection and the sub injection will be described with reference to FIG.

FIG. 3 schematically shows the fuel composition in the fuel tank 13 and the fuel composition in the liquefied fuel recovery container 16. In the drawing, C4, C5, C6... Represent the carbon number, and it is generally known that the fuel having a higher carbon number has a higher boiling point and is more likely to adhere to a cylinder wall or the like at the time of fuel injection, that is, to become wet easily. . According to the figure, it is understood that the fuel stored in the liquefied fuel recovery container 16 has a very small proportion of the high-boiling components that are apt to be wet, which means that the fuel in the liquefied fuel recovery container 16 also has a vaporization characteristic. It is an excellent fuel. In other words, according to the sub-injection, the cylinder wet amount can be reduced as compared with the main injection, the wall temperature of the cylinder 5 is low, and the discharge amount of unburned HC can be reduced even when the engine is started at a low temperature.

Next, the operation of the fuel injection system configured as described above will be described with reference to the flowcharts of FIGS. In the present embodiment, (1) fuel injection by main injection, (2) fuel injection by sub-injection,
(3) fuel injection using both main injection and sub-injection,
In the case of the above (1), only the main injector 11 is driven. In the case of (2), only the sub-injector 12 is driven, and in the case of (3), the main injector 1 is driven.
1 and the sub-injector 12 are simultaneously driven.

FIG. 4 shows a sub-injection routine for controlling the fuel injection by the sub-injector 12, and this routine is executed by the ECU 40 when the ignition key (IG key) is turned on when the engine is started. FIG. 5 shows a main injection routine for controlling the fuel injection by the main injector 11, and the routine is performed every combustion of each cylinder (in this embodiment, 180 ° CA
Each time).

When the IG key is turned on, both the fuel pump 14 on the fuel tank 13 and the fuel pump 17 on the liquefied fuel recovery container 16 are turned on. When the IG is turned on, the routine shown in FIG. 4 is started. First, the ECU 40 determines in step 101 the catalyst temperature Tcat detected by the catalyst temperature sensor 22 and the residual amount in the container detected by the level gauge 34 in the liquefied fuel recovery container 16. The quantity Q is read.

Next, the ECU 40 determines whether or not the catalyst temperature Tcat read in step 102 is lower than a predetermined catalyst activation temperature Tk. If Tcat ≧ Tk (NO in step 102), the ECU 40 determines that sub-injection is unnecessary, for example, when the engine is restarted at a high temperature, and proceeds to step 109. Step 109
Then, the ECU 40 clears the sub-injection flag Fs indicating that the sub-injection is to be performed to “0” and sets the main injection flag Fm that indicates that the main injection is to be performed to “1”. Thereafter, the ECU 40 turns off the fuel pump 17 on the liquefied fuel recovery container 16 side (sub side) in step 110, and ends this routine.

If Tcat <Tk (step 1
If 02 is YES), the ECU 40 proceeds to step 103 and determines the level of the read remaining amount Q in the container. Then, according to the determination result (remaining amount Q in the container), one of the following processings is selected:-Execute only the sub-injection,-Use both the sub-injection and the main injection,-Do not execute the sub-injection I do. Specifically, when the capacity of the fuel pipe 18 between the liquefied fuel recovery container 16 and the sub-injector 12 is set to “pipe capacity Qf”: If Q ≧ 2 × Qf, only the sub-injection is performed. Proceeding to step 104, if Qf ≦ Q <2 × Qf, use sub-injection and main injection together and proceed to step 106; if Q <Qf, do not execute sub-injection (only main injection Is performed), and the process proceeds to step 109.

If Q ≧ 2 × Qf and the routine proceeds to step 104, the ECU 40 sets the sub-injection flag Fs to “1”.
Then, the main injection flag Fm is set to "0". Also,
The ECU 40 injects and supplies the entire fuel injection amount at that time from the sub-injector 12 to the engine main body 1 in the subsequent step 105. Actually, the fuel injection is performed by driving the sub-injector 12 at a predetermined injection timing. At this time, the amount of fuel injected into the engine body 1 is determined by the engine speed and engine load (for example, intake pressure, etc.) at that time, and if air-fuel ratio control is performed, stoichiometric control is performed. To do. Thereafter, if the step 102 is YES (Tcat <Tk) and Q ≧ 2 × Q
As long as the state of f is continued, the ECU 40 performs steps 101 to
The processing is repeatedly executed in the order of 103 → 104 → 105 → 101.

If Qf ≦ Q <2 × Qf and the routine proceeds to step 106, the ECU 40 sets both the sub-injection flag Fs and the main injection flag Fm to “1”.
In the following step 107, the ECU 40 determines the ratio (%) of the sub-injection in the total injection amount according to the relationship in FIG. According to the characteristics of the solid line in FIG. 6, the remaining amount Q in the container is “Qfｆ2
In the range of “× Qf”, the ratio of the sub-injection is determined according to the Q value at each time. After that, the ECU 40 injects and supplies an injection amount corresponding to the ratio of the sub-injection determined in step 108 from the sub-injector 12 to the engine body 1. Thereafter, step 102 is YES (Tcat <T
k) and as long as Qf ≦ Q <2 × Qf,
The CU 40 performs steps 101 to 103 → 106 → 107
The processing is repeatedly executed in the order of → 108 → 101.

Further, if Q <Qf and step 109
The ECU 40 determines that the amount of fuel that can be supplied does not remain in the liquefied fuel recovery container 16. And
The ECU 40 operates the sub-injection flag Fs to “0” and the main injection flag to “1” (step 10).
9) Stop the sub fuel pump 17 (step 11).
0), and then this routine ends.

On the other hand, when the routine of FIG. 5 starts,
First, in step 201, the ECU 40 determines the state of the main injection flag Fm. Further, the ECU 40 determines the state of the sub-injection flag Fs in step 202. Fm =
If the value is 0, the entire injection amount is supplied from the sub-injector 12 (step 105 in FIG. 4). Therefore, E
The CU 40 once ends this routine as it is.

When Fm = 1 and Fs = 1, a part of the total injection amount is supplied from the sub-injector 12 (step 108 in FIG. 4). Therefore, the ECU 4
If the value is 0, the process proceeds to step 203, where the ratio (%) of the main injection in the total injection amount is determined according to the relationship shown in FIG. At this time,
The proportion of the main injection in the total injection amount is determined according to the remaining amount Q in the container at each time based on the characteristics of the two-dot chain line in FIG. Thereafter, the ECU 40 injects and supplies an injection amount corresponding to the ratio of the main injection determined in step 204 from the main injector 11 to the engine body 1.

When Fm = 1 and Fs = 0, the sub-injection is not performed. Therefore, the ECU 40 proceeds to step 205 and injects and supplies all of the fuel injection amount at that time from the main injector 11 to the engine body 1.
Thereafter, fuel injection into the engine body 1 is performed only by the main injector 11.

In this embodiment, steps 204 and 205 in FIG. 5 correspond to first fuel supply means described in the claims, and steps 105 and 108 in FIG. 4 correspond to second fuel supply means. I do. Step 102 in FIG. 4 corresponds to a catalyst activation determination unit.

According to the embodiment described above, the following effects can be obtained. (A) In the present embodiment, a liquefied fuel recovery container 16 for storing the evaporated fuel discharged from the fuel tank 13 and liquefied in the first evaporation passage 24 is provided. When the fuel amount in the fuel tank 16 exceeds a predetermined level, the liquefied fuel stored in the container 16 is injected and supplied to the engine.

In short, the fuel stored in the liquefied fuel recovery container 16 is obtained by liquefying and recovering the fuel once evaporated in the fuel tank 13, and has a lower boiling point than the fuel in the fuel tank 13. The proportion of components that are easily converted is large. Therefore, when fuel is supplied using this fuel, a component that adheres to the cylinder wall without vaporizing (a component having a high boiling point)
, The amount of fuel adhering to the cylinder wall surface (cylinder wet amount) is reduced. In other words, the emission of unburned HC in the exhaust stroke can be significantly reduced as compared with the existing device. As a result, the object of the present invention, such as suppressing the emission of unburned HC at the time of starting the engine at a low temperature, is achieved.

(B) The main injection by the main injector 11 and the sub-injection by the sub-injector 12 are selectively used, and the main injection and the sub-injection are adjusted while adjusting the ratio of the main injection and the ratio of the sub-injection. We decided to use them together. At this time, the ratio of each injection is determined according to the amount of fuel in the liquefied fuel recovery container 16 (remaining amount Q in the container). In this case, the fuel in the liquefied fuel recovery container 16 can be suitably injected and supplied to the engine. Further, even if the amount of fuel in the liquefied fuel recovery container 16 is relatively small,
The fuel can be used effectively without interfering with the operation of the engine. That is, even if the amount of fuel used from the liquefied fuel recovery container 16 is small, the cylinder wet amount is reduced as compared with the case where only the fuel in the fuel tank 13 is supplied to the engine (the entire supply amount is the fuel in the tank). The effect of is obtained.

(C) The degree of activation of the three-way catalyst 21 is determined from the catalyst temperature Tcat, and the sub-injection is performed during the period until the activation of the catalyst. In other words, it takes about 30 seconds for the three-way catalyst 21 in the cold state to be activated and exhibit the original purifying function, and the sub-injection is continued until then. After the activation of the catalyst 21, even if unburned HC due to cylinder wet is discharged from the engine, the unburned HC is purified by the catalyst 21, so that the fuel in the liquefied fuel recovery container 16 does not need to be used. It does not cause air pollution.

(D) The liquefied fuel recovery container 16 is arranged as close as possible to the canister 26. In this case, the first evaporation passage 24 connecting the fuel tank 13 and the liquefied fuel recovery container 16 becomes long, and heat exchange in the passage 24 promotes liquefaction of the evaporated fuel. Therefore, fuel can be efficiently recovered in the liquefied fuel recovery container 16.

(E) In the conventional system without the liquefied fuel recovery container 16, the liquefied fuel in the evaporative passage is also flushed with the rise of the internal pressure of the fuel tank, and the canister 26
Was to be adsorbed. In contrast, in the system of the present embodiment, the liquefied fuel vapor
Since it is stored just before 6, the amount of steam flowing into the canister 26 is reduced. This also has the advantage that the canister 26 can be reduced in size.

(F) As a conventional technique for reducing HC,
For example, it has been considered to accelerate the activation of the catalyst at the time of starting the engine. However, even if the activation of the catalyst is accelerated, the problem of HC emission still remains during the activation. On the other hand, in the present embodiment, HC reduction can be realized without waiting for activation of the catalyst.

The embodiment of the present invention can be realized in the following modes other than the above. In the above-described embodiment, in the sub-injection routine of FIG. 4 described above, whether or not sub-injection is to be performed is determined based on the pipe capacity Qf (capacity of the fuel pipe 18). The execution conditions of the sub-injection may be appropriately changed according to the conditions.

In the above embodiment, the liquefied fuel recovery container 1
6, (1) fuel injection by main injection, (2) fuel injection by sub-injection,
(3) fuel injection using both main injection and sub-injection,
Although the above three processes are selectively executed, this configuration may be changed. For example, the fuel injection of (1) and (2) is switched, and the fuel injection of (3) is not performed. In such an embodiment, the object of the present invention can be achieved. In such a case, processing such as determining the injection ratio based on the relationship in FIG. 6 can be omitted.

In the above embodiment, the catalyst temperature sensor 22
Has been used to determine whether or not sub-injection is necessary (step 102 in FIG. 4), but this configuration is changed. For example, the catalyst temperature (the degree of activation of the catalyst) is estimated based on the engine water temperature, the elapsed time from the start of the engine, and the like, and the necessity of sub-injection is determined based on the estimation result. Also, the activation time of the catalyst when the engine is started at a low temperature (time during which exhaust gas can be purified)
Is estimated, and the sub-injection is performed within a period until the activation time elapses. In this case, using the relationship shown in FIG.
The catalyst activation time may be estimated based on the engine water temperature when the IG is on.

The present invention is applied to a so-called direct injection type engine. In this case, an injector provided on the engine cylinder head is used as a “main injector”.
In such a case, if a cold start injector is provided in the intake port, the injector is used as a “sub-injector”.

Instead of the sub-injector, a carburetor provided near the throttle of the intake pipe is used. That is, fuel supply is performed by the carburetor instead of “sub-injection”. The carburetor may be mechanical or electronically controlled.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an outline of a fuel injection system for an engine according to an embodiment of the invention.

FIG. 2 is a sectional view showing a configuration of a suction valve provided in a liquefied fuel recovery container.

FIG. 3 is a diagram showing a difference between a fuel composition in a fuel tank and a fuel composition in a liquefied fuel recovery container.

FIG. 4 is a flowchart showing a sub injection routine.

FIG. 5 is a flowchart showing a main injection routine.

FIG. 6 is a graph for setting a ratio of a sub-injection and a ratio of a main injection in the total injection amount.

FIG. 7 is a graph for estimating a catalyst activation time according to an engine water temperature.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine main body, 2 ... Intake pipe, 11 ... Main injector, 12 ... Sub-injector, 13 ... Fuel tank, 1
6: liquefied fuel recovery container, 21: three-way catalyst, 22: catalyst temperature sensor, 24: first evaporation passage, 26: canister
34... A level gauge constituting fuel amount detecting means, 40.
An ECU (electronic control device) that constitutes the first fuel supply means, the second fuel supply means, and the catalyst activation determination means.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 69/04 F02M 69/04 W (72) Inventor Hitoshi Maeda 1-1-1 Showa-cho, Kariya-shi, Aichi Pref.

Claims (6)

[Claims] 1. A fuel supply device for an engine, wherein evaporated fuel generated in a fuel tank is once adsorbed to a canister, and the evaporated fuel adsorbed on the canister is discharged to an engine intake system and burned by the engine. A liquefied fuel recovery container that is provided in the middle of a communication passage between the fuel tank and the canister and stores the evaporated fuel discharged from the fuel tank and liquefied in the communication passage; and a fuel amount for detecting a fuel amount in the liquefied fuel recovery container. Detecting means; first fuel supply means for supplying the fuel in the fuel tank to the engine; and when the detected amount of fuel in the liquefied fuel recovery container exceeds a predetermined level under a low temperature starting state of the engine. And a second fuel supply means for supplying liquefied fuel stored in the container to the engine. 2. A fuel supply device for an engine having a main injector and a sub-injector, wherein the first fuel supply means drives the main injector to inject and supply fuel in a fuel tank to the engine. 2. The engine fuel supply device according to claim 1, wherein the second fuel supply means drives the sub-injector to inject and supply liquefied fuel in the liquefied fuel recovery container to the engine. 3. The two fuel supply means are used together while adjusting the fuel supply amount by the first fuel supply means and the fuel supply amount by the second fuel supply means at a predetermined ratio. The fuel supply device for an engine according to claim 1 or 2. 4. The fuel supply device for an engine according to claim 3, wherein a ratio between a supply amount of fuel by the first fuel supply unit and a supply amount of fuel by the second fuel supply unit is set to be the same. A fuel supply device for an engine that determines a fuel amount in the liquefied fuel recovery container according to the detected fuel amount. 5. A catalytic converter for purifying exhaust gas of an engine, and a catalyst activation determining unit for determining activation of the catalytic converter, wherein the second fuel supply unit is configured to activate the catalytic converter. The fuel supply device for an engine according to any one of claims 1 to 4, wherein the liquefied fuel in the liquefied fuel recovery container is supplied to the engine during a period until the determination is made. 6. The fuel supply device for an engine according to claim 1, wherein the liquefied fuel recovery container is disposed as close as possible to the canister.