JP2003343365A - Fuel supply system of internal combustion engine and failure diagnostic device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent unburnt HC resulting from the adhesion of fuel to the wall surfaces of cylinders or the like from emanating into the atmosphere during cold start. <P>SOLUTION: Fuel supply is effected by a main injector 31 which injects fuel collected in a fuel tank 4 and a sub-injector 32 which injects the vaporized fuel in the fuel tank 4. The vaporized fuel is continually and stably generated by generating air bubbles using an air bubble generating means 56 immersed in the fuel collected in the fuel tank 4. During a warming process or the like, the fuel supply by the sub-injector 32 which supplies the vaporized fuel containing large amounts of low-boiling-point components is selected to control the adhesion of the fuel. <P>COPYRIGHT: (C)2004,JPO

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 internal combustion engine and a failure diagnosis system therefor, and more particularly to reducing unburned HC.

[0002]

2. Description of the Related Art An internal combustion engine such as a gasoline engine is provided with a fuel supply means which is constructed so that the liquid phase fuel stored in a fuel tank is pumped up by a fuel pump when the engine is in operation and the supply and the stop of the fuel can be switched. A fuel supply device for supplying fuel for a predetermined time is provided, and the fuel from the fuel supply means is provided for combustion in the combustion chamber. The fuel supply means is composed of an injector that injects and supplies fuel from the injection hole at the tip of the nozzle, and atomizes the fuel to improve combustion efficiency and reduce incomplete combustion. Some unburned H
Although unburned components such as C are discharged to the exhaust system together with the exhaust gas in the exhaust stroke, the exhaust system is provided with a catalyst for purifying the unburned components.

[0003]

However, when the internal combustion engine is started, particularly when the internal combustion engine is cold, the fuel injected by the injector is likely to adhere to the low temperature inside wall surface of the cylinder during the intake stroke immediately before combustion. The unburned HC discharged to the exhaust system tends to increase. Immediately after starting the internal combustion engine, and particularly immediately after starting during cold, the catalyst of the exhaust system does not rise to the activation temperature, and in that case, not only the supplied fuel does not contribute to combustion, Unburned HC may be discharged into the atmosphere without being purified.

The present invention has been made in view of the above circumstances.
An object of the present invention is to provide a fuel supply device for an internal combustion engine and a failure diagnosis device therefor capable of reducing unburned HC.

[0005]

According to a first aspect of the present invention, there is provided a fuel tank configured to store fuel, and a fuel supply configured to be switchable between supply and stop of fuel used for combustion in a combustion chamber during engine operation. A fuel supply device for an internal combustion engine, comprising: first fuel supply means for injecting and supplying the stored fuel pumped up from a fuel tank, and fuel supply means for injecting and supplying evaporated fuel in the fuel tank. 2 fuel supply means, which is immersed in the stored fuel in the fuel tank to generate bubbles, and the evaporated fuel in the fuel tank is sent to the second fuel supply means. Fuel supply cutoff for switching between boosting pump and each of the first fuel supply means and the second fuel supply means depending on the engine operating state whether to permit or prohibit fuel supply. A configuration that includes the example means.

By generating bubbles, saturated vapor of fuel diffuses into a space above the liquid level of the stored fuel in the fuel tank. That is, the evaporated fuel is stably generated in the fuel tank. Evaporated fuel contains a large amount of fuel components having a relatively low boiling point. Therefore, by allowing the fuel supply by the second fuel supply means for supplying the evaporated fuel in the fuel tank to, for example, the warm-up process immediately after the start, the adhesion of fuel is suitable even if the cylinder wall surface is low in temperature. Can be prevented. Thereby, unburned HC can be reduced.

According to a second aspect of the invention, in the configuration of the first aspect of the invention, the second fuel supply means is configured to inject and supply the evaporated fuel to the intake port of each cylinder.

By utilizing the advantage of multi-point injection, it is possible to reduce the variation in fuel injection among cylinders, and it is also excellent in responsiveness.

According to a third aspect of the present invention, in the structure of the first aspect of the invention, the second fuel supply means is a fuel vapor in a surge tank provided in an intake pipe through which intake air to the combustion chamber flows. Is configured to be injected and supplied.

Although the fuel supply by the second fuel supply means is a single-point injection, as described above, it is difficult for fuel to adhere, and even if it is a single-point injection, the discharge of unburned HC is suppressed and the cleanliness of exhaust gas is improved. Is improved.

According to a fourth aspect of the invention, in the structure of the first aspect of the invention, the second fuel supply means is the first fuel cell.
It is arranged adjacent to the fuel supply means and the fuel is injected and supplied to substantially the same position.

With any of the fuel supply means, the fuel is injected at substantially the same position so that the mixture formation and the like are not biased between the two fuel supply means.

According to a fifth aspect of the invention, in the structure of the first to fourth aspects of the invention, the fuel supply switching means is adapted to supply one of the fuel supplied by the first and second fuel supply means. Set to allow selectively.

The internal combustion engine normally holds the evaporated fuel generated in the fuel tank temporarily on the adsorbent in the canister,
Such evaporated fuel is used for combustion in the combustion chamber together with normal injection fuel during engine operation. When the fuel supply amount is corrected by the feedback control of the air-fuel ratio, the feedback control may not be properly performed especially in the transient state, and the exhaust emission may be deteriorated.
In the present invention, since the fuel is supplied once by only one of the first and second fuel supply means, the feedback control of the air-fuel ratio is properly performed.

According to a sixth aspect of the invention, in the configuration of the fifth aspect of the invention, the fuel supply time is corrected once by the fuel supply means by the feedback control of the air-fuel ratio of the combustion chamber, and the fuel supply is switched. When the fuel supply time by the second fuel supply means is an upper limit value set in advance and the air-fuel ratio is lean, the means is
The fuel supply by the first fuel supply means is prohibited and the fuel supply by the first fuel supply means is permitted.

The reason why the air-fuel ratio becomes lean despite the fact that the fuel supply time for one time is long is that the evaporated fuel is not sufficiently sent out from the fuel tank. At this time, therefore, the stored fuel is pumped up. By switching to the fuel supply by the first fuel supply means to be used, the shortage of the fuel supply amount can be avoided.

Further, if the fuel supply by the second fuel supply means cannot be covered due to an increase in the throttle opening, etc.,
Since the fuel supply is automatically switched to the fuel supply by the first fuel supply means, the fuel supply can be switched smoothly.

According to a seventh aspect of the invention, in the structure of the first to sixth aspects of the invention, the fuel supply switching means is set so as to allow the fuel supply by the second fuel supply means during the warm-up process. To do.

Even in the warm-up process in which the temperature of the cylinder wall surface is lower than that during steady operation and fuel is particularly likely to adhere, the generation of unburned HC is suppressed and the cleanliness of exhaust gas can be improved.

According to an eighth aspect of the invention, in the configuration of the fifth or sixth aspect of the invention, the internal combustion engine is a direct injection type configuration in which the first and second fuel supply means directly supply the injected fuel into the combustion chamber. The fuel supply switching means allows the fuel supply by the second fuel supply means during stratified charge combustion and during homogeneous combustion in the warm-up process, and allows the fuel supply by the first fuel supply means during homogeneous combustion after the warm-up process. Set to allow supply.

In the fuel supply by the second fuel supply means, fuel containing a large amount of low boiling point components is supplied, so that stratified charge combustion in which combustion is difficult to stabilize can be realized even in the warm-up process.

According to a ninth aspect of the invention, in the structure of the first to eighth aspects of the invention, the bubble generating means is constituted by an air discharging means having an outlet for discharging the supplied air into the fuel.

As compared with the method of sloshing and heating the stored fuel, it is possible to generate a stable and sufficient amount of bubbles easily.

According to a tenth aspect of the invention, in the configuration of the ninth aspect of the invention, a fuel remaining amount detecting means for detecting the remaining amount of the fuel stored in the fuel tank is provided, and the fuel supply switching means is provided. When the remaining fuel amount is equal to or less than the lower limit threshold value, the fuel supply by the second fuel supply means is prohibited.

When the liquid level of the stored fuel is so low that the air discharging means is not immersed in the stored fuel in the fuel tank at the height of the discharge port, bubbles are not properly generated. If the lower limit threshold value is set in consideration of the liquid surface position, it is possible to know the lack of fuel supply capacity to the second fuel supply means.

According to an eleventh aspect of the invention, in the structure of the ninth or tenth aspect of the invention, the evaporated fuel generated in the fuel tank is temporarily held by the adsorbent in the canister, and the combustion chamber is operated during engine operation. A pipe that is configured to be used for combustion in the air, and that has a pipe through which air taken in from the outside and delivered to the air discharge means flows through the canister to reach the air discharge means. Use as a road.

The fuel adsorbed on the adsorbent in the canister is
The air used for generating the bubbles can be desorbed and used for fuel supply by the second fuel supply means. Moreover, even if the intake negative pressure is small, sufficient air circulates in the canister due to the action of the booster pump, and good purging can be performed. It is excellent in cost-effectiveness because there is no need to install a dedicated pipe or a pump for purging.

According to a twelfth aspect of the present invention, in the configuration of the eleventh aspect of the present invention, the pipeline is provided with an air pump for pumping air flowing through the pipeline.

The air delivery capacity can be improved.

According to a thirteenth aspect of the present invention, in the structure of the eleventh to twelfth aspects of the invention, a fuel adsorption amount detecting means for detecting the amount of adsorption of fuel in the adsorbent in the canister is provided, and the fuel supply is performed. Switching means,
When the adsorbed amount is small, the fuel supply by the second fuel supply means is prohibited.

The fuel is supplied by the second fuel supply means only when the air supplied to the air discharge means contains a sufficient amount of evaporated fuel from the canister. Therefore, the evaporated fuel newly generated by the generation of air bubbles is generated. Is relatively small.
Therefore, the flow rate of the air supplied to the air discharging means can be reduced correspondingly, and the structure does not become large.

According to a fourteenth aspect of the present invention, in the configuration of the thirteenth aspect of the present invention, the pipe line is provided with an air pump for pressure-feeding the air flowing through the pipe line, and
The fuel adsorption amount detection means is constituted by a tank internal pressure detection means for detecting the internal pressure of the fuel tank, and it is understood that the faster the rising speed of the fuel tank internal pressure during the operation of the air pump, the smaller the fuel adsorption amount. To do.

When air is supplied to the canister, air and
The evaporated fuel desorbed by the air is discharged.
When the adsorbent has a large amount of adsorbed fuel, the flow rate of the air-fuel mixture of air and the evaporated fuel desorbed by the air tends to be smaller than when the adsorbed amount is small even under the same environmental conditions. Since the degree of increase in the internal pressure of the fuel tank depends on the volume of the taken-in air-fuel mixture, that is, the flow rate, it can be determined that the higher the increasing rate of the internal pressure of the fuel tank, the smaller the amount of adsorbed fuel. Since the fuel adsorption amount is known only by adding the pressure sensor, it is easy to implement.

According to a fifteenth aspect of the invention, in the structure of the eleventh to fourteenth aspects of the invention, the fuel supply switching means is adapted to supply one of the fuels supplied by the first and second fuel supply means. Setting to allow selectively, and to allow fuel supply by the second fuel supply means after a preset reference time has elapsed since the fuel supply by the first fuel supply means was allowed To do.

Even when the fuel supply by the first fuel supply means is allowed, the evaporated fuel is naturally generated in the fuel tank and is sent to the canister. Therefore, the second fuel is generated every time the reference time elapses. By switching to the fuel supply by the fuel supply means, the newly generated evaporated fuel is appropriately eliminated, and the absolute amount of evaporated fuel in the canister itself can be reduced when the engine is stopped.

According to the sixteenth aspect of the present invention, in the structure of the twelfth to fifteenth aspects of the invention, the tank internal pressure detecting means for detecting the internal pressure of the fuel tank and the tank internal pressure are set to a preset reference pressure. And an air pump control means for controlling the air pump.

The evaporated fuel in the fuel tank is saturated vapor, and the fuel supply amount to the second fuel supply means can be stabilized by keeping the fuel tank internal pressure constant.

According to a seventeenth aspect of the invention, in the configuration of the sixteenth aspect of the invention, an opening / closing valve for closing the pipe line is provided upstream of the canister, and the air pump control means is opened / closed together with the air pump. A control means for controlling the valve is set, and the air pump is stopped and the on-off valve is closed when the tank internal pressure reaches the reference pressure.

In the stopped state of the air pump, the hermeticity of the space extending from the canister to the fuel tank to the second fuel supply means can be improved. As a result, the operating time of the air pump can be reduced, energy consumption can be reduced, and the air pump can be used for a long life.

In the eighteenth aspect of the invention, in the configuration of the seventeenth aspect of the invention, the air pump control means is set to open the on-off valve when the engine is stopped.

It is possible to prevent the air containing the evaporated fuel from being jetted from the fuel filler port of the fuel tank.

Since the second fuel supply means side and the fuel tank side are separated at the booster pump position, a certain amount of evaporated fuel is held in the piping for flowing evaporated fuel to the second fuel supply means. It Therefore, it is possible to avoid a fuel supply shortage when the fuel supply by the second fuel supply means is permitted by restarting.

According to a nineteenth aspect of the invention, in the configuration of the seventeenth aspect of the invention, when the engine of the air pump control means is stopped, the on-off valve is closed, and the oil supply port is opened when refueling. Prior to the above, the on-off valve is set to open.

At the time of refueling, the on-off valve is opened in advance to release the pressurized state in the fuel tank, so that the fuel can be prevented from being diffused from the refueling port together with the pressurized air. When refueling is not performed, the pressurized state in the fuel tank is maintained, and the energy required to pressurize to a predetermined pressure at the next start can be suppressed.

According to a twentieth aspect of the invention, there is provided a failure diagnosis device for a fuel supply system for an internal combustion engine according to the twelfth to nineteenth aspects.
An on-off valve that closes the pipeline on the upstream side of the canister, a tank internal pressure detection unit that detects the internal pressure of the fuel tank, and an air pump that operates with the on-off valve closed to add the fuel tank interior. Pressurize, the greater the rate of decrease of the fuel tank internal pressure after stopping the air pump,
The fuel cell, the canister, and the leak determining means for determining that the area of the evaporative leak hole connecting the second fuel supply means is large are provided.

If there is a leak hole in the evaporation system, the pressure drop from the pressurized state becomes faster, so the extent of the leak hole can be known from the pressure drop rate. Since it is not necessary to additionally provide a means for pressurizing the inside of the fuel tank for failure diagnosis, the cost can be reduced accordingly. Particularly, when the fuel supply device has the structure of claims 14 and 16, the tank internal pressure detection means and the opening / closing valve are common, which is particularly cost-effective.

According to a twenty-first aspect of the invention, there is provided a failure diagnosis device configuration of a fuel supply system for an internal combustion engine according to the twelfth to nineteenth aspects of the invention, wherein a drive power detecting means for detecting drive power of the air pump and the drive power are provided. It is configured to include a characteristic deterioration determination unit that recognizes that the larger it is, the lower the characteristic of the air discharging unit.

For example, if clogging occurs in the discharge port of the air discharging means, the load of the air pump increases and the driving power increases. Therefore, the degree of clogging can be known from the magnitude of the driving power. It is possible to know the characteristic deterioration of the air discharging means without directly detecting the bubble generation state at the discharge port. Moreover, it is easy because it is sufficient to check the driving power.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows the configuration of an internal combustion engine according to a first embodiment to which the present invention is applied. This embodiment is applied to, for example, an automobile engine. In a cylinder 101 formed in a cylinder block 11 of a main body (hereinafter, appropriately referred to as an engine main body) 10 of an internal combustion engine, a piston 13 that reciprocates in the vertical direction in the drawing is arranged, and the piston 13 includes a connecting rod 14. It is connected to a crank shaft (not shown) via the. A cylinder head 12 is attached to the cylinder block 11 from above to close the cylinder 101 at its upper end, and the piston 13
A combustion chamber 102 is formed above. The combustion chamber 102 communicates with the intake port 15 when the intake valve 17 is open, and communicates with the exhaust port 16 when the exhaust valve 18 is open. The intake port 15 communicates with an intake pipe 21, and the exhaust port 16 communicates with an exhaust pipe (not shown). The intake pipe 21 is provided with a throttle valve 22 downstream of the air cleaner 23 and upstream of the surge tank 24, which works in conjunction with an accelerator pedal (not shown) to adjust the intake amount.

The fuel supply system for supplying the fuel that forms the air-fuel mixture with the intake air flowing through the intake pipe 21 will be described. A main injector 31, which is a first fuel supply means for injecting fuel from the tip, is provided in the intake port 15 so as to penetrate the cylinder head 12 and faces the intake port 15, and during the valve opening period. Fuel can be supplied to the intake port 15. The main injector 31 is connected to the fuel pump 35 in the fuel tank 4 via the first fuel line 33. The fuel pump 35 pumps up the stored fuel in the fuel tank 4 and pumps it to the main injector 31 via the first fuel line 33.

A sub-injector 32, which is a second fuel supply means for injecting fuel from the tip, is provided in the vicinity of the main injector 31 so as to penetrate the cylinder head 12 and faces the intake port 15 and opens. During the valve period
Fuel can be supplied to the intake port 15. The sub-injector 32 is attached so as to inject fuel toward the same position as the main injector 31. The sub-injector 32 constitutes a part of the evaporated fuel processing device, and the fuel is supplied from the sub-injector 32 using the function of the evaporated fuel processing device.

The evaporated fuel processing device will be described. The fuel tank 4 is connected to the sub-injector 32 by a second fuel line 34 whose one end is open on the inner surface of the ceiling thereof. The sub-injector 3 is installed in the second fuel line 34.
A booster pump 36 for pumping fuel to the fuel tank 2 is provided. The booster pump 36 may be provided for each cylinder, or may be common to all the cylinders.

The second fuel line 34 is branched in the middle to form an evaporation line 53, which is connected to the canister 51 filled with the adsorbent 52 with one end wall 511 thereof. The connection end of the evaporation line 53 with the canister 51 is open to the inner surface of the canister end wall 511. An internal pressure valve 54 is provided in the middle of the evaporation line 53. Internal pressure valve 5
Reference numeral 4 denotes a check valve whose forward direction is from the fuel tank 4 toward the canister 51. When fuel is evaporated in the fuel tank 4, the pressure in the fuel tank 4 (hereinafter, appropriately,
The internal pressure valve 54 opens due to the increase in the fuel tank internal pressure),
The evaporated fuel moves into the canister 51. Canister 5
Within 1, the evaporated fuel is temporarily adsorbed by the adsorbent 52.

On the inner surface of the canister end wall 511, one end of the purge line 55 is opened in addition to the evaporation line 53. The other end of the purge line 55 penetrates the ceiling of the fuel tank 4 and extends to the bottom of the fuel tank 4.

A perforated plate 56, which is an air discharging means, is installed at the bottom of the fuel tank 4 and is normally immersed in the stored fuel in the fuel tank 4. As shown in FIG. 2, the perforated plate 56 is a flat rectangular parallelepiped container body with a hollow inside, and a large number of small-diameter through holes are opened in the entire ceiling surface 561 and is a discharge port. It is provided as a bubble ejection hole 562. Further, on the side surface of the perforated plate 56, a through hole communicating with each bubble ejection hole 562 through the hollow portion 563 is opened, and serves as a steam introduction port 564. The perforated plate 56 is connected to the purge line 55, which is a pipe line, at the steam introduction port 564. Therefore, the perforated plate 56 is always in communication with the canister 51 via the purge line 55. As will be described later in detail, the perforated plate 56 is a means for generating bubbles, and when air is delivered from the canister 51, bubbles are ejected from the bubble ejection holes 562 into the stored fuel.

The atmosphere line 57 is connected to the other end wall 512 of the canister 51, and one end of the atmosphere line 57 is open to the inner surface of the end wall 512. Atmosphere line 5
The other end of 7 is open to the atmosphere. An air pump 58 and a canister closed valve (hereinafter referred to as CCV) 59 which is an opening / closing valve are provided in the middle of the atmosphere line 57 from the canister 51 side. The CCV 59 is a two-way valve that closes the atmosphere line 57 at its installation position, and the air pump 58 can send atmospheric pressure into the canister 51 with the CCV 59 being “open”. A drive circuit (not shown) of the air pump 58 is composed of a constant voltage circuit, and drives the air pump 58 at a constant voltage.

The main injector 31, the fuel pump 35, the sub-injector 32, the booster pump 36, the air pump 58, and the CCV 59 are each controlled by an electronic control unit (ECU) 61 which controls each part of the internal combustion engine. The ECU 61 has a basic configuration for a general internal combustion engine, and is adapted to give a predetermined injection timing, a fuel injection amount, etc. according to the depression amount of the accelerator pedal and the like.
Here, feedback control of the air-fuel ratio in the combustion chamber 102 is performed by learning control, and the length of the valve opening period of the injectors 31, 32 that regulates the fuel injection amount is corrected.

The operating conditions used for the control in the ECU 61 are given by various sensors. As a sensor for inputting a detection signal to the ECU 61, a catalyst temperature sensor 62 for detecting the temperature of a catalyst provided in the exhaust pipe, An engine water temperature sensor 63 for detecting the temperature of the cooling water, and a fuel remaining amount sensor 6 for detecting the remaining amount of fuel stored in the fuel tank 4.
4. An air-fuel ratio sensor 65 for detecting the air-fuel ratio in the combustion chamber 102 based on the O2 concentration of exhaust gas is provided. Also,
The fuel tank 4 is provided with a fuel tank internal pressure sensor 66 that detects the internal pressure of the fuel tank. A drive current sensor 67, which is drive power detection means for detecting the drive current of the air pump 58, is provided.

Further, a warning light 68 is provided on the instrument panel in the vehicle compartment to indicate when an abnormality occurs in the internal combustion engine. The warning light 68 is turned on by being driven by the ECU 61.

Next, the operation of the internal combustion engine will be described with reference to the flowchart of FIG. This shows the control contents in the ECU 61 as the fuel supply switching means and the pump control means. When the IG switch is turned on,
Fuel supply by the sub-injector 32 is allowed (step S100). When the fuel supply by the sub-injector 32 is permitted, the fuel supply by the main injector 31 is prohibited. Further, as will be described later, when the fuel supply by the main injector 31 is permitted, the fuel supply by the sub-injector 32 is prohibited. In this way, one of the fuel supply by the main injector 31 and the fuel supply by the sub-injector 32 is selectively allowed. At this time, the valve opening period and the like are calculated according to the injection characteristics of the injectors 31, 32 that are allowed.

When the fuel supply by the sub-injector 32 is allowed, the air pump 58 is operated and
CCV59 also opens. As a result, air is pumped to the canister 51 by the air pump 58, and the canister 5
The fuel is desorbed from the first adsorbent 52 and is delivered to the booster pump 36 through the porous plate 56 and the fuel tank 4. Further, although the internal pressure of the fuel tank rises, when the internal pressure of the fuel tank reaches a preset reference pressure, the driving of the air pump 58 is stopped and the CCV 59 is closed. At a predetermined fuel injection timing, the sub-injector 32 opens to supply fuel. At this time, a predetermined injection pressure is given by the operation of the boost pump 36.

The fuel injection timing and the injection amount are calculated by the ECU 61 according to the operating conditions as described above, and the injection amount is given as the length of the valve opening period of the sub-injector 32.

Since the fuel tank internal pressure is lowered by the fuel supply, the CCV 59 is opened again and the air pump 58 is operated to raise the fuel tank internal pressure to the reference pressure.
Repeat this.

The following steps S101 to S105 are a procedure for reviewing the setting that allows fuel supply by the sub-injector 32. In step S101, the catalyst temperature Tcat detected by the catalyst temperature sensor 62, the engine water temperature Tw detected by the engine water temperature sensor 63, and the fuel remaining amount Q detected by the fuel remaining amount sensor 64 are read.

Steps S102 and S103 are procedures for determining whether or not the warm-up process is in progress. In step S102,
The catalyst temperature Tcat read in step S101 is compared with a preset catalyst activation temperature Tk, and the catalyst temperature Tcat is compared.
Is below the catalyst activation temperature Tk. If an affirmative decision is made, the operation proceeds to step S103, and if a negative decision is made, it is considered that the warm-up process has been exited and the operation proceeds to step S105.

In step S103, the engine water temperature Tw
Is compared with a preset warm-up completion temperature Th to determine whether the engine water temperature Tw is lower than the warm-up completion temperature Th. If an affirmative decision is made, the operation proceeds to step S105, and if a negative decision is made, it is assumed that the warm-up process has been exited and step S1.
Go to 05.

In step S104, the remaining fuel amount Q is compared with a preset lower limit threshold value Qmin to determine whether the remaining fuel amount Q is equal to or more than the lower limit threshold value Qmin. Here, the lower limit threshold value Qmin is a state in which the perforated plate 56 is completely immersed in the fuel, that is, the liquid level of the stored fuel is the upper surface 56 of the perforated plate 56 where the bubble jet port 562 opens.
The fuel quantity is set to a value slightly higher than 1. If an affirmative decision is made in step S104, the operation proceeds to step S106, in which the fuel supply by the sub-injector 32 is maintained as allowed. When a negative determination is made in step S104, it is determined that bubbles cannot be generated and the process proceeds to step S105.

In step S105, a canister adsorption amount determination process is executed. This is done as follows. As described above, when the fuel injection by the sub-injector 32 is allowed, the air pump 58 repeats the operating state and the stopped state. At this time, the air pump 58 starts operating and then returns to the reference pressure. The required time until it is measured is calculated, and the adsorption amount of the evaporated fuel adsorbed by the adsorbent 52 of the canister 51 is calculated based on the required time and the remaining fuel amount Q. This takes advantage of the fact that if the adsorbed amount of the evaporated fuel decreases, the rate of pressure increase increases and the required time decreases as described above. The reason why the remaining fuel amount Q is taken into consideration is that if the remaining fuel amount Q is small, the pressurized volume in the fuel tank 4 increases and the required time also increases. Therefore, for each remaining fuel amount Q within the predetermined range, the relationship between the required time and the adsorbed amount is calculated, and this is calculated as EC.
It is stored as a map or the like in the ROM of U61, and the adsorption amount is obtained based on the map.

This adsorption amount is compared with a preset lower limit threshold value to determine whether or not the adsorption amount is larger than the lower limit threshold value. If an affirmative determination is made, it is determined that fuel remains in the canister 51, and the process proceeds to step S106.
This is because the residual fuel in the canister 51 is discharged in the form of fuel injection from the sub-injector 32.

When the determination in step S105 is negative, the process proceeds to step S108, and the fuel supply by the main injector 31 is allowed as will be described later. First, the fuel supply by the sub-injector 32 is maintained while being allowed. The case where it is performed will be described.

The fuel supplied to the booster pump 36 comes from the fuel tank 4. As described above, the air pump 58 is operated to send the air from the canister 51 to the fuel tank 4, and the evaporated fuel desorbed from the adsorbent 52 is sent to the fuel tank 4 together with the air. The evaporated fuel and air are ejected as bubbles from the bubble ejection holes 562 of the perforated plate 56 immersed in the liquid fuel, and are discharged to a space above the liquid surface of the stored fuel. At this time, the evaporated fuel has a saturated vapor pressure that depends on the temperature of the fuel. That is, the saturated vapor is delivered from the second fuel line 34 to the booster pump 36. Then, the evaporated fuel contains a large amount of components having a relatively low boiling point among the fuel components. This makes it difficult for the fuel injected into the intake port 15 to adhere to the wall surface of the intake port 15 and the wall surface of the cylinder 101.

As described above, it is determined that the fuel supply by the sub-injector 32 is maintained while being allowed to be maintained during the warm-up process (steps S102 and S103), and the remaining fuel amount Q is equal to or higher than the lower limit threshold value Qmin. Is. The perforated plate 56 is provided at the bottom of the fuel tank 4, and in most cases, the refueling is performed before it extremely decreases. Therefore, in the warm-up process, the perforated plate 56 was immersed in the stored fuel. In this state, the fuel is supplied by the sub-injector 32, so that the fuel adhesion can be suppressed even when the wall surface of the cylinder 101 or the like is warming up at a low temperature.

If the remaining amount of fuel Q is not sufficient and the porous plate 56 is not immersed, the vaporized fuel having a low boiling point cannot be supplied in this manner, but the amount of fuel adsorbed in the canister 51 does not increase. If sufficient (step S10
5) Fuel supply by the sub-injector 32 is allowed,
Fuel adhesion can be suppressed.

Next, a case will be described in which the adsorbed fuel in the canister 51 is small and a negative determination is made in step S105. In this case, in step S108 the air pump 58
Is fixed to the inoperative state, and step S109 is performed.
CCV59 is fixed in the open state.

Then, in the subsequent step S110, the fuel supply by the sub-injector 32 is prohibited, and the fuel supply by the main injector 31 is allowed instead. As a result, at a predetermined injection timing, the main injector 31 opens the valve to inject fuel. Here, it goes without saying that the injection amount calculated from the accelerator opening degree or the like is calculated so as to be suitable for the main injector 31.

In step S111, it is determined whether the allowable fuel supply is switched from the fuel supply by the sub-injector 32 to the fuel supply by the main injector 31 (step S110) and the elapsed time t has reached a predetermined time t0. judge. If a negative decision is made, step S11.
Returning to 0, the allowance of fuel supply by the main injector 31 is maintained.

When the elapsed time t, that is, the time during which the fuel supply by the main injector 31 is allowed reaches the reference time t0, and the affirmative decision is made in step S111, the operation proceeds to step S106, in which the main injector 3
Instead of the fuel supply by 1, the fuel supply by the sub-injector 32 is allowed as described above. That is, the adsorbed fuel in the canister 51 is small, and the main injector 31
Even when the fuel supply by the sub-injector 32 is permitted, the fuel supply by the sub-injector 32 is permitted when the reference time t0 elapses. This brings about the following effects. Even after all the adsorbed fuel in the canister 51 has been exhausted, the fuel vaporizes in the fuel tank 4 and flows into the canister 51 to be adsorbed by the adsorbent 52. If this exceeds the adsorption capacity of the adsorbent 52, it will cause the leakage of evaporated fuel. Each time the reference time t0 elapses, the sub-injector 32 once
By allowing the fuel supply by the above, the adsorbed fuel can be appropriately discharged.

Therefore, as the predetermined time t0, the fuel adsorption amount at a certain elapsed time is measured in advance, and a reference time t0 is set in which there is a certain amount of adsorbed fuel and the adsorption amount does not exceed the adsorption capacity of the adsorbent 52. . EC is the reference time t0
It is stored in the ROM of U61. The certain elapsed time depends on the capacity of the fuel tank 4 and can be roughly estimated.

When the canister 51 has adsorbed fuel, the CCV 59 is fixed to the open state after the air pump 58 is fixed to the stopped state (step S).
108, S109), the CCV 59 may be closed. As a result, from the fuel tank 4 to the canister 51
The internal space leading to is closed and the internal pressure of the fuel tank is maintained,
Sub-injector 3 through steps S110 and S111
When the fuel supply by 2 is allowed (step S10
6) It is unnecessary to increase the fuel tank internal pressure to the reference pressure, the number of times the air pump 58 is driven is reduced, and it is possible to reduce energy consumption and improve the life of the air pump 58.

Step S107 following step S106
The following procedure will be described. In the fuel supply by the sub-injector 32, the injection amount is corrected by feedback control of the air-fuel ratio based on the air-fuel ratio detected by the air-fuel ratio sensor 65, but if the concentration of the evaporated fuel becomes low, the injection period becomes long. In step S107, it is determined whether the injection amount is a preset maximum injection amount and the detected air-fuel ratio is lean. If a negative decision is made, the operation proceeds to step S112 to decide whether or not the IG is off.

When the determination in step S112 is negative, the process returns to step S100, and the procedure after step S100 is executed.

If the determination in step S107 is affirmative, it means that there is no room for returning to the stoichiometric side even if the injection amount is increased, and the process proceeds to step S110 to allow the fuel supply by the main injector 31. This is the case when the supply of evaporated fuel is insufficient during the warm-up process, or when the vehicle actually starts running and the intake amount increases due to an increase in the accelerator opening.

Then, the IG is turned off, and the step S1 is executed.
If the determination in step S12 is affirmative, the air pump 58 is fixed in the stopped state in step S113, and step S113 is performed.
At 114, the CCV 59 is fixed in a valve open state. Accordingly, it is possible to prevent the pressurized air in the fuel tank 4 from being jetted from the fuel filler port 41 together with a part of the evaporated fuel during fueling.

The second fuel line 34 has a range from the booster pump 36 to the sub-injector 32 to some extent.
Since the airtightness is ensured, a sufficient amount of fuel can be immediately supplied from the sub-injector 32 at the time of restart.

As described above, in the present internal combustion engine, the fuel supply by the sub-injector 32 is basically prioritized during engine warm-up. In the fuel supply by the sub-injector 32, since the fuel contains a large amount of low-boiling point components, it is possible to preferably prevent fuel adhesion even when the wall surface of the cylinder 101 and the like are low in temperature during the warm-up process, particularly during cold start. It is possible to preferably prevent the unburned HC from being discharged in the exhaust stroke. Further, as a result, it is not necessary to increase the fuel injection amount by the amount that the adhered fuel does not contribute to combustion in the related art, which is not necessary, and the fuel efficiency can be improved. Further, one fuel injection is performed by the main injector 31.
Alternatively, the air-fuel ratio control can be properly performed even in the transient state by performing only one of the sub-injectors 32.

As long as the evaporated fuel can be supplied to the sub-injector 32, the fuel supply by the sub-injector 32 is executed (step S106). Whether or not (steps S102 and S103) and the result of the feedback control of the air-fuel ratio (step S107) are determined, the fuel injection by the main injector 31 is automatically switched to the main mode at an appropriate time. At this time, cylinder 1
01 Wall surface temperature is rising, fuel adhesion itself is reduced, and even if unburned HC is discharged to the exhaust system, it is purified because the catalyst is sufficiently activated and is diffused into the atmosphere. Can be prevented.

Further, since the fuel supply by the sub-injector 32 is performed by the driving force of the booster pump 36 and the air pump 58 regardless of the intake negative pressure, there is no shortage of air for purging the adsorbed fuel of the adsorbent 52. .

Further, since the sub-injectors 32 are provided in a one-to-one correspondence with each cylinder, there is no variation among the cylinders and the responsiveness is excellent.

Further, the air pump 58 is operated so that the fuel tank internal pressure detected by the fuel tank internal pressure sensor 66 becomes constant, and saturated fuel vapor is stored in the fuel tank 4, so that the fuel supply by the sub-injector 32 is performed. Can be performed stably.

It should be noted that when the engine is stopped (step S11
2) The CCV 59 is opened (step S11)
In 4), the valve may be closed. In this case, since the inside of the evaporation system is maintained in a pressurized state, the amount of electric power required to pressurize the fuel tank 4 to the reference pressure by the air pump 58 at the time of restart is small, and energy consumption can be suppressed. . In this case, at the time of refueling, in order to prevent the pressurized air in the fuel tank 4 from being jetted from the fuel refueling port 41 together with the evaporated fuel at the time of refueling, prior to opening the refueling port 41. , CCV59 should be opened. This is, for example, provided with a switch for detecting the open / closed state of the refueling door of the vehicle body provided at the refueling port 41 position, and when it is detected that the door is opened, CCV5
The ECU 61 may be set so that the valve 9 is opened.

Further, the ECU 61 uses the tank internal pressure sensor 6
6, a drive current sensor 67, a warning light 68, and a failure diagnosis device for an internal combustion engine, in particular, an evaporated fuel processing device portion, are executed by the ECU 61 which is a leak determination means and a characteristic deterioration determination means in FIGS. 2 shows a failure diagnosis flow.
What is diagnosed in FIG. 4 is whether or not there is a risk of evaporative fuel leakage, and what is diagnosed in FIG. 5 is clogging of the bubble discharge holes 562 of the porous plate 56.

The failure diagnosis flow is executed after a fixed time has elapsed since the engine was stopped. Immediately after the engine is stopped, the inside of the fuel tank 4 that constitutes the evaporated fuel processing device may be unstable, so failure diagnosis can be avoided to avoid erroneous determination.
Diagnosis of leakage of evaporated fuel will be described. The evaporative system, which is a combination of the fuel tank 4, the canister 51, and the lines 34, 53, 55 connecting these, forms one space in the inner space in which the evaporated fuel can diffuse when the engine is stopped. The leakage of evaporated fuel from the inner space to the outside of the evaporation system is diagnosed as follows. Step S2
At 00, the air pump 58 is driven to pressurize the inside of the evaporation system. Then, in step S201, the fuel tank internal pressure is detected by the fuel tank internal pressure sensor 66, and it is determined whether or not the fuel tank internal pressure has reached a preset pressure P1. Of course, the set pressure P1 is set to a pressure value higher than the atmospheric pressure.

When the determination in step S201 is negative, the process returns to step S200 and the air pump 58 continues to pressurize the evaporation system.

When the affirmative judgment is made in step S201, the CCV 59 is closed in step S202, and the air pump 58 is turned off in step S203. At this time, the evaporative system is a closed space unless there is a leak hole as a failure.

If there is a leak hole as a failure, gas leaks from the leak hole, and the fuel tank internal pressure P rapidly decreases. In step S204 following step S203, the fuel tank internal pressure P is compared with the set pressure P2, and the fuel tank internal pressure P is set to the set pressure P.
Determine if higher than 2. The determination time is after the air pump 58 is turned off (step S203) and a predetermined time set in advance has elapsed. Therefore, if the fuel tank internal pressure P is higher than the set pressure P2 when the predetermined time has elapsed, the rate of decrease of the fuel tank internal pressure P is slow, and if it is low, the rate of decrease of the fuel tank internal pressure P is fast.

When the determination in step S204 is affirmative, in step S205, it is determined that there is a leak hole in any of the evaporative systems, the warning light 68 is turned on to display the abnormality, and the driver is informed. To do. When a negative determination is made in step S204, it is recognized as normal in step S206.
It should be noted that the larger the area of the leak hole, the faster the rate of decrease of the fuel tank internal pressure P becomes, and therefore the set pressure P2 is set to the lower limit value at which it can be determined to be normal. Here, the fuel tank internal pressure P
Since the rate of decrease of the pressure depends on the volume of the evaporative pressure space, it is preferable to make it variable according to the remaining fuel amount that defines the volume of the evaporative pressure space.

As described above, the air pump 58 and the tank internal pressure sensor 66 are also used for pressurization in the evaporative system at the time of leakage diagnosis, so that the cost increase due to the leakage diagnosis function can be suppressed. it can.

Next, the bubble ejection holes 56 of the perforated plate 56.
The diagnosis of the second clogging will be described. In step S300, the fuel tank internal pressure detected by the fuel tank internal pressure sensor 66 is taken in, and the air pump 58 is operated in step S301.

The driving power of the air pump 58 increases as the load increases. When the air pump 58 is driven at a constant drive voltage as described above, the drive current changes according to the load. Here, the load increases as the pressure on the discharge side of the air pump 58, that is, the higher the internal pressure of the fuel tank, but the bubble ejection holes 562 of the perforated plate 56 are clogged with foreign matter or the like, and the flow resistance here changes. Also changes, and the drive current increases as the clogging increases.

In step S302, the drive current I of the air pump 58 detected by the current sensor 67 is compared with a preset current I0, and the drive current I is determined to be the predetermined current I0.
Is greater than. If an affirmative decision is made, in step S303, the warning lamp 68 is lit to indicate that the bubble ejection hole 562 is clogged, and an abnormality is displayed to notify the driver. When a negative determination is made in step S302, it is recognized as normal in step S304. The warning light 68 for clogging the perforated plate 56 is different from the one for evaporative leakage.

Since the drive current I increases as the bubble ejection hole 562 is clogged, the predetermined current I0 is set to an upper limit value that can be determined to be normal. The relationship between the internal pressure of the fuel tank and the drive current I is calculated by using a new porous plate 56.
It is better to obtain the above through experiments in advance.

Air pump 58, tank internal pressure sensor 66
Is used also for diagnosing the clogging of the bubble ejection holes 562 of the porous plate 56, it is possible to suppress the cost increase due to the addition of the clogging diagnostic function.

By providing the CCV 59, it is possible to reduce the energy consumption by intermittently operating the air pump 58 and to check the evaporative system for leaks. However, the invention is not limited to this, and the sub-injector is not limited thereto. While the fuel supply by 32 is allowed, the air pump 58 may be operated at all times.

(Second Embodiment) FIG. 6 shows an internal combustion engine according to a second embodiment of the present invention. The internal combustion engine is the first
The fuel supply position by the sub-injector is changed in the configuration of the embodiment, and the parts that operate substantially the same as those in the first embodiment are denoted by the same reference numerals and the description focuses on the differences from the first embodiment. To do. In this internal combustion engine, the sub-injector is common to all the cylinders, and is attached to the surge tank 24 so as to penetrate the tank wall and inject fuel into the surge tank 24.

The ECU 61A is basically the same as that of the first embodiment, and executes the control according to the control flow of FIGS. The difference is that the fuel supply by the sub-injector 32 is a single point injection. Conventionally, due to the method of single-point injection, there is fuel that remains in the intake pipe 21 and the intake port 15 before being sucked into the combustion chamber 102. Although it has a defect that it easily adheres to the inner wall surface of 21, the application of the present invention can eliminate such a defect.

(Third Embodiment) FIG. 7 shows an internal combustion engine according to a third embodiment of the present invention. The present internal combustion engine is the one in which the present invention is applied to a direct injection engine, and parts that perform substantially the same operations as those of the first embodiment will be denoted by the same reference numerals, and the description will focus on the differences from the first embodiment. To do. In the present internal combustion engine, a main injector 31 and a sub-injector 32 are attached so that their tip ends project into the combustion chamber 102. Fuel is supplied to the main injector 31 by a first fuel pump 35a stored in the fuel tank 4 and a second fuel pump 35b that pumps the delivered fuel at a position immediately upstream of the main injector 31, Increasing injection pressure.

The ECU 61B is basically the same as that of the first embodiment, and executes the control according to the control flow of FIGS. The difference is that, when fuel is supplied, stratified combustion and homogeneous combustion are selected based on the engine operating state.

Here, fuel supply by the sub-injector 32 is permitted during stratified combustion and homogeneous combustion in the warm-up process, and fuel supply by the main injector 31 is permitted during homogeneous combustion after the warm-up process.

In the fuel supply by the sub-injector 32, fuel containing a large amount of low boiling point components is supplied, so stratified charge combustion in which combustion is difficult to stabilize can be realized even in the warm-up process, and fuel consumption and exhaust emission can be reduced. .

(Fourth Embodiment) FIG. 8 shows an internal combustion engine according to a fourth embodiment of the present invention. The internal combustion engine is the first
In the configuration of the embodiment, the configuration of the fuel supply by the sub-injector is changed, and the parts that operate substantially the same as those of the first embodiment are designated by the same reference numerals and the differences from the first embodiment are mainly focused. Explained. The internal combustion engine does not include an air pump that pressurizes the inside of the fuel tank 4 so that the internal pressure of the fuel tank becomes a predetermined pressure.

The ECU 61C is basically the same as that of the first embodiment, and executes the control according to the control flow of FIGS. The difference is that the air pump is not operated so that the internal pressure of the fuel tank becomes a predetermined pressure. Canister 5
The adsorbed fuel in 1 is supplied through the porous plate 56 and the fuel tank 4 by the operation of the booster pump 36. Therefore, the internal pressure of the fuel tank does not exceed the atmospheric pressure.

Since the air pump is omitted, the structure can be simplified.

Further, the specific embodiment of the present invention is arbitrary as long as it does not violate the gist of the present invention in addition to the above-mentioned respective embodiments. For example, the air-fuel ratio control is made good by selectively allowing only one of the main injector 31 and the sub-injector 32, but both may be allowed at the same time. Even in this case, it is desirable that only the fuel supply by the sub-injector 32 is allowed in the warm-up process in which fuel adhesion is likely to occur, but it is not excluded that the fuel supply by the main injector 31 is allowed. Since fuel is supplied by the sub-injector 32, fuel adhesion can be suppressed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first internal combustion engine to which a fuel supply device and a failure diagnosis device of the present invention are applied.

2A is a plan view of a component of the internal combustion engine, and FIG. 2B is a sectional view taken along line IIB-IIB.

FIG. 3 is a first flowchart showing a control content executed by an ECU that controls each part of the internal combustion engine.

FIG. 4 is a second flowchart showing the control contents executed by an ECU that controls each part of the internal combustion engine.

FIG. 5 is a third flowchart showing the control contents executed by an ECU that controls each part of the internal combustion engine.

FIG. 6 is a configuration diagram of a second internal combustion engine to which the fuel supply device and the failure diagnosis device of the present invention are applied.

FIG. 7 is a configuration diagram of a third internal combustion engine to which the fuel supply device and the failure diagnosis device of the present invention are applied.

FIG. 8 is a configuration diagram of a fourth internal combustion engine to which the fuel supply device and the failure diagnosis device of the present invention are applied.

[Explanation of symbols]

10 Engine Body 11 Cylinder Block 12 Cylinder Head 13 Piston 14 Connecting Rod 15 Intake Port 16 Exhaust Port 17 Intake Valve 18 Exhaust Valve 101 Cylinder 102 Combustion Chamber 21 Intake Pipe 22 Throttle Valve 23 Air Cleaner 24 Surge Tank 31 Main Injector (First Fuel Supply Means) 32 sub-injector (second fuel supply means) 33 first fuel line 34 second fuel lines 35, 35a, 35b fuel pump 36 booster pump 4 fuel tank 41 fuel filler 51 canister 52 adsorbent 53 evaporation line 54 Pressure valve 55 Purge line (pipe line) 56 Perforated plate (bubble generation means, air discharge means) 561 Upper surface 562 Bubble discharge hole (discharge port) 57 Atmosphere line (pipe line) 58 Air pump 59 CCV (open / close valve) 61, 61A, 1B, 61C ECU (fuel supply switching means, air pump control means, leak determination means, characteristic deterioration determination means) 62 catalyst temperature sensor 63 engine water temperature sensor 64 fuel level sensor (fuel level detection means) 65 air-fuel ratio sensor 66 fuel tank Internal pressure sensor (fuel adsorption amount detection means) 67 Drive current sensor (drive power detection means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 25/08 F02M 25/08 301L 301S 301U 37/00 311 37/00 311H (72) Inventor Takano Kono 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Incorporated Japan Auto Parts Research Institute, Inc. (72) Inventor Naoya Kato 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi In-house Japan Auto Parts Research Institute (72) Nobuhiko Koyama 1-1-1, Showa-cho, Kariya city, Aichi Stock company DENSO F-term (reference) 3G044 AA05 BA06 BA22 CA02 CA03 CA04 DA02 DA07 DA09 EA03 EA08 EA12 EA32 EA40 EA49 EA55 FA04 FA09 FA13 FA16 FA23 FA24 FA27 FA30 FA39 FA40 GA02 GA04 GA08 GA04 GA08 GA08 GA08 GA08 GA09 GA10 GA11 GA16 GA22 GA24 GA27

Claims (21)

[Claims] 1. A fuel supply device for an internal combustion engine, comprising: a fuel tank for storing fuel; and a fuel supply means configured to be switchable between supply and stop of fuel used for combustion in a combustion chamber during engine operation. The fuel supply means comprises first fuel supply means for injecting and supplying the stored fuel pumped up from the fuel tank, and second fuel supply means for injecting and supplying the evaporated fuel in the fuel tank, and Bubble generating means for generating bubbles by being immersed in the stored fuel in the fuel tank, a booster pump for delivering evaporated fuel in the fuel tank to the second fuel supply means, the first fuel supply means, and For each of the second fuel supply means, whether to allow or prohibit the fuel supply,
A fuel supply device for an internal combustion engine, comprising: a fuel supply switching unit that switches in accordance with an engine operating state. 2. The fuel supply apparatus for an internal combustion engine according to claim 1, wherein the second fuel supply means injects and supplies evaporated fuel to an intake port of each cylinder. 3. The fuel supply device for an internal combustion engine according to claim 1, wherein the second fuel supply means injects evaporated fuel into a surge tank provided in an intake pipe through which intake air to the combustion chamber flows. Fuel supply device for internal combustion engine. 4. The fuel supply device for an internal combustion engine according to claim 1, wherein the second fuel supply means is arranged adjacent to the first fuel supply means, and the fuel is injected and supplied to substantially the same position. Fuel supply device for internal combustion engine. 5. The fuel supply device for an internal combustion engine according to claim 1, wherein the fuel supply switching means is configured to supply one of the fuel supplied by the first and second fuel supply means. A fuel supply device for an internal combustion engine set to allow selectively. 6. The fuel supply device for an internal combustion engine according to claim 5, wherein the fuel supply time is corrected once by the fuel supply means by feedback control of the air-fuel ratio of the combustion chamber. , The one-time fuel supply time by the second fuel supply means is a preset upper limit value,
Further, when the air-fuel ratio is lean, the fuel supply device for the internal combustion engine is set so that the fuel supply by the second fuel supply means is prohibited and the fuel supply by the first fuel supply means is allowed. 7. The fuel supply device for an internal combustion engine according to claim 1, wherein the fuel supply switching means is set to allow fuel supply by the second fuel supply means during a warm-up process. Supply device for internal combustion engine. 8. The fuel supply device for an internal combustion engine according to claim 5, wherein the internal combustion engine is the first or second fuel supply device.
Is a direct injection type structure for directly supplying the injected fuel into the combustion chamber, and the fuel supply switching means controls the fuel supply by the second fuel supply means at the time of stratified combustion and at the time of homogeneous combustion in the warm-up process A fuel supply device for an internal combustion engine, which is set to allow the fuel supply by the first fuel supply means at the time of homogeneous combustion after the warm-up process. 9. A fuel supply system for an internal combustion engine according to any one of claims 1 to 8, wherein the bubble generating means is constituted by an air discharge means having a discharge port for discharging supplied air into fuel. Fuel supply system. 10. The fuel supply device for an internal combustion engine according to claim 9, further comprising a fuel remaining amount detecting means for detecting a remaining amount of the fuel stored in the fuel tank, the fuel supply switching means comprising: A fuel supply device for an internal combustion engine, wherein the fuel supply by the second fuel supply means is prohibited when the remaining amount becomes equal to or less than the lower limit threshold. 11. The fuel supply system for an internal combustion engine according to claim 9, wherein the evaporated fuel generated in the fuel tank is temporarily held by an adsorbent in a canister, and the combustion chamber is operated during engine operation. A pipe that is configured to be used for combustion in the air, and that has a pipe through which the air taken in from the outside and sent to the air discharge means flows through the canister to reach the air discharge means. Fuel supply system for internal combustion engine. 12. The fuel supply system for an internal combustion engine according to claim 11, wherein the pipeline is provided with an air pump for pressure-feeding air flowing through the pipeline. 13. The fuel supply system for an internal combustion engine according to claim 11 or 12, further comprising a fuel adsorption amount detection means for detecting the amount of adsorption of fuel in the adsorbent in the canister. A fuel supply device for an internal combustion engine, wherein the switching means is set to prohibit the fuel supply by the second fuel supply means when the adsorption amount is small. 14. The fuel supply system for an internal combustion engine according to claim 13, wherein the pipeline is provided with an air pump for pressure-feeding the air flowing through the pipeline, and the fuel adsorption amount detection means is provided with A fuel supply device for an internal combustion engine, comprising a tank internal pressure detection means for detecting the internal pressure of a fuel tank, and determining that the fuel adsorption amount is smaller as the rising speed of the fuel tank internal pressure during operation of the air pump is faster. 15. The fuel supply device for an internal combustion engine according to claim 11, wherein the fuel supply switching means is adapted to supply one of the fuel supplied by the first and second fuel supply means. To allow selectively,
Further, when a preset reference time elapses after the fuel supply by the first fuel supply unit is allowed, the second
A fuel supply device for an internal combustion engine, which is set to allow fuel supply by the fuel supply means. 16. A fuel supply system for an internal combustion engine according to claim 12, wherein the tank internal pressure detecting means for detecting an internal pressure of the fuel tank and the tank internal pressure are set to a preset reference pressure. A fuel supply device for an internal combustion engine, comprising: an air pump control means for controlling an air pump. 17. The fuel supply system for an internal combustion engine according to claim 16, further comprising an opening / closing valve that closes the conduit on the upstream side of the canister, the air pump control means including the opening / closing valve together with the air pump. A fuel supply device for an internal combustion engine, which is a control unit for controlling, and is configured to stop the air pump and close the on-off valve when the tank internal pressure reaches the reference pressure. 18. The fuel supply system for an internal combustion engine according to claim 17, wherein the air pump control means is set to open the open / close valve when the engine is stopped. 19. The fuel supply system for an internal combustion engine according to claim 17, wherein when the air pump control means stops the engine, the on-off valve is closed, and at the time of refueling, prior to opening the refueling port. A fuel supply device for an internal combustion engine configured to open the on-off valve. 20. A failure diagnosis device for a fuel supply device for an internal combustion engine according to claim 12, wherein an on-off valve closing the pipe line upstream of the canister, and an internal pressure of the fuel tank. Tank pressure detecting means for detecting the fuel pressure in the fuel tank by operating the air pump in a state where the on-off valve is closed. A failure diagnosing device for a fuel supply device for an internal combustion engine, comprising: a tank, the canister, and leak determining means for determining that the area of an evaporative leak hole connecting the second fuel supplying means is large. 21. A failure diagnostic device for a fuel supply system for an internal combustion engine according to claim 12, further comprising: drive power detection means for detecting drive power of the air pump; A failure diagnosis device for a fuel supply device for an internal combustion engine, comprising: a characteristic deterioration determination means that is determined to be a characteristic deterioration of the discharge means.