JP2012036769A - Leak detection method in fuel supply system, and leak diagnosis device in the fuel supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a leak detection method for a fuel supply system that detects a leak state in a fuel supply system of an internal combustion engine with high accuracy without depending on a pressure sensor and can perform an accurate diagnose, and to provide a leak detection method in a fuel supply system.SOLUTION: The leak detection method seals a fuel tank to be an airtight state by a seal valve (S108). The leak detection method detects a deformation quantity in a profile of the fuel tanks as a deformation quantity ΔSGL between an initial fuel liquid level SGLini and a fuel liquid surface level SGLa after a predetermined time DTa passes by using a fuel sender gauge (S106, S110-S114). The leak detection method performs the leak determination (S116-S120) by the liquid surface change quantity ΔSGL. Since the leak determination is based on differences in the inside and outside of the profile, a pressure relationship between the inside and the outside is properly reflected, and an accurate leak diagnosis can be performed without using the pressure sensor.

Description

  The present invention relates to a leak detection method and a leak diagnosis apparatus in a fuel supply system of an internal combustion engine.

  In various internal combustion engines such as those for driving a vehicle, fuel from a fuel tank is supplied into intake air or into a combustion chamber. Furthermore, in such a fuel tank, in order to prevent the fuel vapor generated inside from being released into the atmosphere, the fuel vapor is collected by a canister, and the fuel collected in the intake air is released during operation of the internal combustion engine. (Purge).

  In such a fuel tank or a mechanism such as a canister connected thereto, if fuel vapor leaks due to a failure of a hole or a valve, the fuel vapor is unnecessarily released into and out of the internal combustion engine. As a result, the internal combustion engine may be drivable and environmental problems may occur.

Therefore, it is necessary to detect such a leak at an early stage and take countermeasures. For this reason, techniques for detecting the leak have been proposed (see, for example, Patent Documents 1 to 4).
In Patent Document 1, a fuel tank and a canister connected to the fuel tank through a charge passage are sealed in an airtight state, the sealed portion is pressurized by a pressurizing device, and a leak is detected based on the pressure change. An error has been detected.

In Patent Document 2, the inside of a variable capacity fuel tank is pressurized by an air pump, and a leak state is detected from the change in the internal pressure.
In Patent Document 3, the inside of the system is depressurized by an air pump in a state where the evaporation purge system including the fuel tank and the canister is closed, and a leak state is detected from the degree of the negative pressure. Here, since the degree of the negative pressure is affected by the deformation of the fuel tank, a leak determination value for determining the negative pressure state is set in consideration of the degree of deformation of the fuel tank.

  In Patent Document 4, when the internal combustion engine is stopped, the evaporation purge system including the fuel tank and the canister is sealed, and then, if the internal pressure exceeds the determination value within a predetermined time, it is determined that there is no leak, and if it does not exceed, the leak is determined. ing. However, when the internal pressure suddenly changes, it is assumed that the volume of the resin fuel tank is suddenly changed, and the leak determination is stopped to avoid the influence of the pressure change due to the deformation of the fuel tank.

JP-A-6-346801 (pages 4-6, FIGS. 1, 2, 9) JP 2007-113405 A (Page 3, FIG. 2) JP2009-293615A (pages 4-6, FIGS. 1 and 2) JP 2003-83176 A (6th and 7th pages, FIGS. 1, 5 and 7)

  In Patent Documents 1 to 3, leak determination is performed based on a pressure change in the evaporation purge system by positively pressurizing or depressurizing the sealed evaporation purge system with an air pump. In Patent Document 4, leak determination is performed based on a pressure change in an evaporation purge system that is sealed when the internal combustion engine is stopped, without performing positive pressurization or pressure reduction. In this way, both techniques detect leaks based on pressure changes in the evaporation purge system.

  In this way, when the internal pressure of the evaporation purge system is detected by the pressure sensor and the leak is detected by the change in the value, the deformation of the fuel tank is affected as described in Patent Documents 3 and 4. For this reason, as described in Patent Document 4, it may be difficult to detect leakage due to pressure.

  Moreover, the pressure detection by the pressure sensor only detects the internal pressure of the fuel tank as it is. However, this internal pressure value does not always reflect the leak state between the closed system and the outside. That is, the internal pressure of the fuel tank or its change may not be due to the absence of a leak, but may be due to the internal pressure being influenced by the external pressure due to the leak. Alternatively, the internal pressure of the fuel tank or its change may not be due to leakage, but may simply be due to a change in vapor pressure due to condensation or evaporation in the closed system.

  It is an object of the present invention to provide a fuel supply system leak detection method and a fuel supply system leak diagnosis device capable of detecting a leak state in a fuel supply system of an internal combustion engine with high accuracy without using a pressure sensor and executing an accurate leak diagnosis. To do.

In the following, means for achieving the above-mentioned purpose, and its operation and effect are described.
According to a first aspect of the present invention, there is provided a fuel supply system leak detection method in which a compartment set in a fuel supply system of an internal combustion engine is sealed in an airtight state, and the leakage of the compartment is determined based on deformation of an outer shell constituting the sealed compartment. It is characterized by detecting a state.

  If there is no leak in the compartment in the fuel supply system that is sealed in an airtight state, the outer shell is subjected to a force on the outer side or the inner side due to the pressure difference between the inner side and the outer side, and the outer shell is deformed according to the pressure difference. Produce.

Therefore, when such deformation is detected in the outline, it can be detected that there is no leak.
Since the deformation of the outer shell is not based only on the pressure inside the outer shell but based on the pressure difference between the inner and outer shells, the relationship between the inner and outer pressures is compared with the conventional technique that detects only the pressure inside the outer shell. Therefore, the leak state can be detected with high accuracy.

  The fuel supply system leak detection method according to claim 2, wherein the fuel supply system leak detection method according to claim 1 detects deformation of the outer shell after a predetermined time has elapsed since the compartment was sealed in an airtight state. The leak state of the section is detected based on the detection result.

  In this way, when the compartment is sealed in an airtight state and the deformation of the outer shell is detected after the predetermined time has elapsed, there is a sufficient pressure difference between the inner and outer shells if there is no leak due to the fuel vapor pressure in the compartment or its change. It is likely that it has occurred. Therefore, the leak state can be detected with higher accuracy by detecting the deformation of the outer shell after the passage of a predetermined time.

  The fuel supply system leak detection method according to claim 3, wherein the blockage that makes the compartment airtight is directly or indirectly external to the compartment. It is performed by closing a valve provided in a path connected to

  When the leak state is not detected, the valve is opened to allow the fuel supply system to function. When the leak state is detected, the valve is closed to block the compartment in an airtight state, thereby detecting the leak state. It becomes.

  According to a fourth aspect of the present invention, there is provided a fuel supply system leak detection method in which a section set in a fuel supply system of an internal combustion engine is brought into a pressurized or depressurized state, and the section A leak state is detected.

  Each of the inventions described in claims 1 to 3 can detect a leak state irrespective of the presence / absence of pressurization / decompression treatment by means such as an air pump. It is possible to detect the leak state of the section based on the deformation of the outer shell in this state, and it is possible to reliably detect the leak state with high accuracy as described above.

  The fuel supply system leak detection method according to claim 5 is the fuel supply system leak detection method according to claim 4, wherein the decompression state of the compartment is performed by introducing an intake negative pressure of an internal combustion engine into the compartment. It is characterized by being.

  The positive pressure reduction state can be realized by introducing the intake negative pressure of the internal combustion engine into the compartment. As a result, a positive depressurized state can be easily realized without providing a mechanism such as an air pump.

  The fuel supply system leak detection method according to claim 6, wherein the outer shell is deformed by a deformation amount larger than a predetermined deformation amount according to any one of claims 1 to 5. In addition, it is determined that there is no leakage because the outer shell is deformed.

  In particular, a predetermined amount of deformation may be provided in consideration of various errors, and no leak may occur when the amount of deformation of the outer shell is larger than the predetermined amount of deformation. This makes it possible to detect leaks more reliably.

  The fuel supply system leak detection method according to claim 7, wherein the compartment is a compartment including a fuel tank. .

  Since the section sealed in an airtight state includes the fuel tank in this way, the outer shell of the fuel tank can be used as an outer shell for detecting deformation. Since the outer area of the fuel tank is larger in area than other parts of the fuel supply system, the pressure difference between the inside and outside is amplified and appears in the deformation amount, so that the leakage state of the compartment can be detected with higher accuracy.

  The fuel supply system leak detection method according to claim 8, wherein the compartment is a compartment including a fuel tank and a canister. Features.

  Since the section sealed in an airtight state is a section including the fuel tank and the canister, the fuel tank and the canister are included based on the deformation of the outer shape of the fuel tank that is manifested by an amplification of the pressure difference between the inside and the outside. About a partition, a leak state can be detected with higher accuracy.

  The fuel supply system leak detection method according to claim 9 is the fuel supply system leak detection method according to claim 7 or 8, wherein the fuel supply system leak detection method according to a pressure difference between the inside and outside of the fuel tank within the outer shell of the fuel tank. It is characterized in that a deformation amount in a portion that is easily deformed is detected, and a leak state of the section is detected based on the deformation amount.

  In a fuel tank, there are a portion that is highly rigid and difficult to deform and a portion that is low rigid and easily deformed due to differences in shape and material. Therefore, when the deformation of the outer shell of the compartment is based on the deformation of the outer shell of the fuel tank, it is possible to detect the deformation amount in the portion that is easily deformed according to the pressure difference between the inner and outer fuel tanks. This makes it possible to detect the leakage state of the partition with higher accuracy.

  The fuel supply system leak detection method according to claim 10, wherein at least a lower outer shell of the fuel tank is an inside / outside of the fuel tank according to any one of claims 7 to 9. The amount of deformation of the lower outer shell is detected based on the amount of change in the liquid level of the fuel stored in the fuel tank.

  When the outer shell on the lower side of the fuel tank is deformed, the fuel in the fuel tank is pushed up or pushed down, and the liquid level changes even if the amount of fuel stored in the fuel tank is constant.

  Therefore, when the outer shell on the lower side of the fuel tank is a portion that is easily deformed according to the pressure difference between the inner and outer sides of the fuel tank, the lower side based on the change in the liquid level of the fuel stored in the fuel tank. It is possible to detect the deformation amount of the outer shell.

  Thus, the means for detecting the liquid level can measure the amount of deformation of the outer shell of the fuel tank, so that it is possible to detect a leak with a conventional fuel meter without providing any special means. . Therefore, it can contribute to weight reduction and cost reduction.

  The fuel supply system leak detection method according to claim 11, wherein the fuel supply system leak detection method according to any one of claims 7 to 9, wherein the portion is easily deformed according to a pressure difference between the inside and outside of the fuel tank. The amount of deformation of the outline is detected based on the amount of change in the distance between the fuel tank and the configuration other than the fuel tank.

The deformation amount of the fuel tank outer shell may be detected based on the amount of change in the distance between the portion that is easily deformed in the fuel tank and the configuration other than the fuel tank.
The fuel supply system leak detection method according to claim 12, wherein the fuel supply system leak detection method according to any one of claims 7 to 9 is easily deformed in accordance with a pressure difference between the inside and outside of the fuel tank. The amount of deformation of the outline is detected on the basis of the amount of change in distortion.

When the outer shell of the fuel tank is deformed, distortion corresponding to the deformation is generated in the outer shell of the fuel tank. Accordingly, the amount of deformation of the outline may be detected based on the amount of change in distortion.
In the fuel supply system leak detection method according to claim 13, in the fuel supply system leak detection method according to any one of claims 1-4 and 6-12, the detection of the leak state is performed by stopping the internal combustion engine. It is characterized by being executed inside.

  In particular, during operation of the internal combustion engine, there is a risk that the vibration will be a disturbance for detecting the amount of deformation transmitted to the outline of the fuel supply system. Therefore, by detecting the leak state described above while the internal combustion engine is stopped, the leak state of the compartment can be detected with higher accuracy.

  In the fuel supply system leak detection method according to claim 14, in the fuel supply system leak detection method according to claim 13, the length of the operation period of the internal combustion engine or the magnitude of the integrated rotational speed immediately before the internal combustion engine is stopped. Accordingly, the detection timing of the leak state while the internal combustion engine is stopped is adjusted.

  The pressure difference between the outside and the outside of the fuel supply system tends to increase especially when the temperature of the internal combustion engine is stopped. The temperature of the fuel supply system depends on the length of the operation period of the internal combustion engine immediately before the internal combustion engine stops or the magnitude of the integrated rotational speed. Therefore, by adjusting the detection timing of the leak state during the stop of the internal combustion engine according to the length of the operation period of the internal combustion engine or the accumulated rotational speed immediately before the stop of the internal combustion engine, an appropriate leak state detection timing can be obtained. It is done.

This makes it possible to detect the leak state as early as possible while ensuring the detection accuracy.
The fuel supply system leak detection method according to claim 15 is the fuel supply system leak detection method according to claim 13, wherein the internal combustion engine is for driving a vehicle and the length of the vehicle travel period immediately before the stop of the internal combustion engine or The detection timing of the leak state while the internal combustion engine is stopped is adjusted according to the length of the travel distance.

  The pressure difference between the outside and the outside of the fuel supply system tends to increase especially when the temperature of the internal combustion engine is stopped. When the internal combustion engine is for driving a vehicle, the temperature of the fuel supply system depends on the length of the vehicle travel period or the travel distance immediately before the internal combustion engine stops. Therefore, by adjusting the leak state detection timing while the internal combustion engine is stopped according to the length of the vehicle travel period or the travel distance immediately before the internal combustion engine is stopped, an appropriate leak state detection timing can be obtained.

This makes it possible to detect the leak state as early as possible while ensuring the detection accuracy.
The fuel supply system leak diagnosis apparatus according to claim 16, wherein the fuel supply system leak diagnosis apparatus is a leak diagnosis apparatus for a fuel supply system of an internal combustion engine, wherein a block set in the fuel supply system of the internal combustion engine is sealed in an airtight state; Deformation amount detecting means for detecting the deformation amount of the outline constituting the compartment, and after the compartment is sealed in an airtight state by the sealing means, based on the deformation amount of the outline detected by the deformation amount detection means. Leak determination means for determining whether or not there is a leak in the section is provided.

  If there is no leak in the section sealed in an airtight state by the sealing means, the outer shell acts on the outer side or the inner side due to the pressure difference between the inner side and the outer side, and the outer shell is deformed according to the pressure difference. .

Therefore, it is possible to determine the presence or absence of leakage in the section based on the deformation amount of the outline detected by the deformation amount detection means after the blockade by the blocking means.
The deformation amount of the outline detected by the deformation amount detecting means is not based only on the pressure inside the outline but based on the pressure difference between the inside and outside of the outline. From this, it is possible to obtain data reflecting the internal / external pressure relationship as compared with the prior art that detects only the pressure inside the outer shell. Therefore, since the leak state detection becomes highly accurate, the leak determination means can accurately determine whether there is a leak.

  The fuel supply system leak diagnosis apparatus according to claim 17, wherein the leak determination means is a predetermined time after the section is sealed in an airtight state by the sealing means. After the elapse of time, the presence / absence of leakage of the section is determined based on the deformation amount of the outline detected by the deformation amount detecting means.

  In this manner, the leak determination means determines whether or not there is a leak based on the outer deformation amount detected by the deformation amount detection means after a predetermined time has elapsed after the block is sealed in an airtight state by the sealing means. In the case where the amount of deformation of the outer shell is detected after a predetermined time after blocking the compartment, there is a high possibility that a pressure difference is sufficiently generated inside and outside the outer shell due to the fuel vapor pressure in the compartment or its change if there is no leak. Therefore, the leak determination means can more accurately determine whether there is a leak or not based on the amount of deformation of the outer shell after a predetermined period of time has elapsed.

  The fuel supply system leak diagnosis device according to claim 18, wherein the blockade means is connected to a path directly or indirectly connected to the outside from the section. The valve is provided.

  Such a valve can be used as the sealing means. Therefore, the leak determination means opens the valve when it does not determine the presence or absence of a leak to function the fuel supply system, and when it determines the presence or absence of leak, closes the valve to make the compartment airtight and the deformation amount detection means Whether or not there is a leak can be determined based on the deformation amount detected in step.

  The fuel supply system leak diagnosis apparatus according to claim 19, wherein the fuel supply system leak diagnosis apparatus is a leak diagnosis apparatus for a fuel supply system of an internal combustion engine, and introduces a positive pressure or a negative pressure into a section set in the fuel supply system of the internal combustion engine. A path, sealing means for sealing the section in an airtight state except for the pressure introduction path, deformation amount detection means for detecting a deformation amount of an outer shell constituting the section, and from the pressure introduction path to the section After the introduction of the positive pressure or the negative pressure and the blocking means by the blocking means, the presence or absence of leakage in the section is determined based on the deformation amount of the outline detected by the deformation amount detecting means. And a leak determination means.

  In each of the inventions described in claims 16 to 18, it is possible to determine the presence or absence of a leak regardless of the presence or absence of pressurization / decompression processing by means such as an air pump. Sometimes, the inside of the compartment may be actively pressurized or depressurized using the pressure introduction path.

As a result, as described above, it is possible to surely determine whether or not there is a leak.
The fuel supply system leak diagnosis apparatus according to claim 20, wherein the introduction of the negative pressure from the pressure introduction path to the compartment is an intake negative pressure of an internal combustion engine. It is the introduction of.

  The positive pressure reduction state can be realized by introducing the intake negative pressure of the internal combustion engine into the compartment from the pressure introduction path. As a result, a positive depressurized state can be easily realized without providing a mechanism such as an air pump.

  The fuel supply system leak diagnosis apparatus according to claim 21, wherein the leak determination means is configured so that a deformation amount of the outer shell is a predetermined deformation amount. If larger, it is determined that there is no leak.

  The leak determination means may provide a predetermined deformation amount in consideration of various errors, and may determine that there is no leak when the deformation amount of the outline detected by the deformation amount detection means is larger than the predetermined deformation amount. . This makes it possible to more reliably determine whether there is a leak.

  23. The fuel supply system leak diagnosis apparatus according to claim 22, wherein the section is a section including a fuel tank. .

  Since the section sealed in an airtight state includes the fuel tank in this manner, the outer shape of the fuel tank can be used as an outer shape for the deformation amount detecting means to detect the deformation amount. Since the outer area of the fuel tank is larger in area than other parts of the fuel supply system, the pressure difference between the inside and outside is amplified and appears in the deformation amount. From this, it is possible to determine the presence or absence of a leak in a partition with higher accuracy.

  In the fuel supply system leak diagnosis apparatus according to claim 23, in the fuel supply system leak diagnosis apparatus according to any one of claims 16 to 21, the section is a section including a fuel tank and a canister. Features.

  Since the section sealed in an airtight state is a section including a fuel tank and a canister, the fuel tank and the canister It is possible to determine the presence or absence of a leak with higher accuracy for a section including

  25. The fuel supply system leak diagnosis apparatus according to claim 24, wherein the deformation amount detecting means is provided within the outer shell of the fuel tank. It is characterized in that the amount of deformation at a portion that is easily deformed is detected according to the pressure difference between the inside and outside.

  In a fuel tank, there are a portion that is highly rigid and difficult to deform and a portion that is low rigid and easily deformed due to differences in shape and material. Therefore, when the deformation amount detection means detects the deformation amount of the outer shell of the fuel tank, the deformation amount may be detected in a portion that is easily deformed according to the pressure difference between the inside and the outside of the fuel tank. As a result, it is possible to determine the presence / absence of a leak in the partition with higher accuracy.

  26. The fuel supply system leak diagnosis apparatus according to claim 25, wherein the fuel tank has at least a lower outer shell inside and outside the fuel tank according to any one of claims 22 to 24. The deformation amount detecting means determines the deformation amount of the lower outer shell based on the amount of change in the liquid level of the fuel stored in the fuel tank. It is characterized by detecting.

  When the outer shell of the fuel tank, in particular, is deformed, the fuel in the fuel tank is pushed up or pushed down, and the liquid level changes even if the amount of fuel stored in the fuel tank is constant.

  Therefore, when the outer shell on the lower side of the fuel tank is a portion that is easily deformed in accordance with the pressure difference between the inside and the outside of the fuel tank, the deformation amount detecting means detects the level of the fuel stored in the fuel tank. Based on the change amount, the deformation amount of the lower outline can be detected.

  Therefore, the fuel meter that detects the fuel level can measure the amount of deformation of the outer shell of the fuel tank, so that the conventional fuel meter can be used without providing a new mechanism for detecting the amount of deformation. It can also be used as deformation amount detection means. For this reason, it can contribute to weight reduction and cost reduction.

  In the fuel supply system leak diagnosis apparatus according to claim 26, in the fuel supply system leak diagnosis apparatus according to claim 25, the fuel tank includes a portion that is easily deformed according to a pressure difference between the inside and the outside, and a portion that is difficult to deform. A center position of the easily deformable portion is spaced apart from the undeformable portion, and the deformation amount detecting means for measuring a fuel level in the fuel tank includes the undeformable portion. It is arranged.

  In particular, when the deformation amount detecting means measures the liquid level, the deformation amount detecting means is arranged in a portion that is difficult to deform according to the pressure difference between the inside and outside of the fuel tank, thereby changing the liquid level. Can be measured accurately.

  Further, in the fuel tank, since the center position of the easily deformable portion is separated from the hardly deformable portion, the deformation amount due to the internal / external pressure difference can be sufficiently generated. As a result, the liquid level can be sufficiently changed, and the presence / absence of leakage can be accurately determined.

  In the fuel supply system leak diagnostic apparatus according to Claim 27, in the fuel supply system leak diagnostic apparatus according to any one of Claims 22 to 24, the deformation amount detecting means determines the deformation amount of the outer shell. It is detected as a change amount of an interval between a portion that is easily deformed according to a pressure difference between the inside and outside of the fuel tank and a configuration other than the fuel tank.

The deformation amount detecting means may detect based on a change amount of an interval between the easily deformable portion and a configuration other than the fuel tank.
29. The fuel supply system leak diagnostic apparatus according to claim 28, wherein the deformation amount detection means uses the deformation amount of the outer shell as the deformation amount of the outer shell. It is characterized by detecting the amount of change in strain at a portion that is easily deformed according to the pressure difference between the inside and outside of the fuel tank.

  When the outer shell of the fuel tank is deformed, distortion corresponding to the amount of deformation is generated in the outer shell of the fuel tank. Therefore, the deformation amount detecting means may detect the amount of change in distortion as a physical quantity representing the amount of deformation of the outline.

  30. The fuel supply system leak diagnosis apparatus according to claim 29, wherein the leak determination means determines whether or not there is a leak. Is executed while the internal combustion engine is stopped.

  By determining whether there is a leak while the internal combustion engine is stopped, it is possible to make a determination in a state where the fuel supply system is extremely stable, including that there is no disturbance such as internal combustion engine operation vibration. Therefore, it is possible to determine the presence or absence of leak with higher accuracy.

  30. The fuel supply system leak diagnostic apparatus according to claim 30, wherein the leak determination means is the length or integration of the operating period of the internal combustion engine immediately before the internal combustion engine is stopped. The magnitude of the rotational speed is measured, and the determination timing of the presence or absence of the leak while the internal combustion engine is stopped is adjusted according to the measurement result.

  The pressure difference between the outside and the outside of the fuel supply system tends to increase especially when the temperature of the internal combustion engine is stopped. The temperature of the fuel supply system depends on the length of the operation period of the internal combustion engine immediately before the internal combustion engine stops or the magnitude of the integrated rotational speed.

  From this, the leak determination means measures the length of the operation period of the internal combustion engine or the magnitude of the integrated rotational speed immediately before the stop of the internal combustion engine. The timing for determining whether or not there is a leak while the internal combustion engine is stopped is adjusted in accordance with the length of the operation period of the internal combustion engine or the magnitude of the integrated rotational speed.

This makes it possible to determine the presence or absence of a leak as early as possible while ensuring the determination accuracy.
The fuel supply system leak diagnostic device according to claim 31 is the fuel supply system leak diagnostic device according to claim 29, wherein the internal combustion engine is for driving a vehicle, and the leak determination means is a vehicle immediately before the stop of the internal combustion engine. The length of the traveling period or the length of the traveling distance is measured, and the determination timing of the presence or absence of the leak while the internal combustion engine is stopped is adjusted according to the measurement result.

  The pressure difference between the outside and the outside of the fuel supply system tends to increase especially when the temperature of the internal combustion engine is stopped. When the internal combustion engine is for driving a vehicle, the temperature of the fuel supply system depends on the length of the vehicle travel period or the travel distance immediately before the internal combustion engine stops.

  From this, the leak determination means measures the length of the vehicle traveling period or the length of the traveling distance immediately before the stop of the internal combustion engine. The timing for determining whether or not there is a leak while the internal combustion engine is stopped is adjusted according to the length of the vehicle travel period or the length of the travel distance.

  This makes it possible to determine the presence or absence of a leak as early as possible while ensuring the determination accuracy.

1 is a schematic configuration diagram of a fuel supply system and a control system of an internal combustion engine according to a first embodiment. 4 is a flowchart of a fuel tank leak diagnosis process executed by the ECU according to the first embodiment. 4 is a timing chart showing an example of control by fuel tank leak diagnosis processing according to the first embodiment. 4 is a flowchart of canister leak diagnosis processing executed by the ECU according to the first embodiment. 4 is a timing chart illustrating an example of control by canister leak diagnosis processing according to the first embodiment. 7 is a flowchart showing a part of a fuel tank leak diagnosis process executed by an ECU according to the second embodiment. 7 is a flowchart showing a part of a fuel tank leak diagnosis process executed by an ECU according to a third embodiment. 10 is a flowchart of canister leak diagnosis processing executed by the ECU according to the fourth embodiment. 9 is a timing chart illustrating an example of control by canister leak diagnosis processing according to the fourth embodiment. (A), (b) In the fifth embodiment, the length of the operation period immediately before the stop of the internal combustion engine, the magnitude of the integrated rotational speed immediately before the stop of the internal combustion engine, and the length of the vehicle travel period immediately before the stop of the internal combustion engine Or the graph showing the predetermined time DTa set according to the length of the vehicle travel distance just before a stop of an internal combustion engine. (A), (b) In Embodiment 6, the length of the operation period immediately before the stop of the internal combustion engine, the magnitude of the integrated rotational speed immediately before the stop of the internal combustion engine, the length of the vehicle travel period immediately before the stop of the internal combustion engine Or a graph representing a predetermined number of times Y set according to the length of the vehicle travel distance immediately before the stop of the internal combustion engine. (A)-(c) Structure explanatory drawing for detecting the deformation | transformation amount of a fuel tank outer shell in Embodiment 7. FIG. 10 is a flowchart of fuel tank leak diagnosis processing executed by an ECU according to the eighth embodiment. (A), (b) Structure explanatory drawing of other embodiment which detects the deformation | transformation amount of the part which made part of the outline of a fuel tank low rigidity.

[Embodiment 1]
FIG. 1 is a schematic configuration diagram of a fuel supply system 4 and a control system of an internal combustion engine 2 to which the above-described invention is applied. The internal combustion engine 2 is a gasoline engine and is mounted on the vehicle for driving the vehicle, and its rotational output is transmitted to the drive wheels of the vehicle via a transmission.

  A fuel injection valve 8 is disposed at the intake port 6 in each cylinder of the internal combustion engine 2. The fuel stored in the fuel tank 10 is pumped to the fuel injection valve 8 by the fuel pump module 12. By fuel injection control, fuel is injected from the fuel injection valve 8 during intake at a predetermined timing, and is sucked into each cylinder and burned. As a result, the internal combustion engine 2 is driven.

A fuel sender gauge 14 for detecting the fuel level SGL in the fuel tank 10 by the float 14a is provided in the fuel tank 10.
The fuel is introduced into the fuel tank 10 during refueling from the fuel inlet pipe 16. A fuel supply port 16b to which a cap 16a is attached is provided at the tip of the fuel inlet pipe 16, and fuel is introduced into the fuel tank 10 from the fuel supply port 16b.

  A circulation pipe 16c connects the fuel supply port 16b and the upper space 10a of the fuel tank 10. A fuel inlet box 16d is formed around the fuel filler opening 16b, and a fuel lid 16e that opens the fuel inlet box 16d when fueling is provided on the front surface of the fuel inlet box 16d.

  The canister 18 includes an adsorbent such as activated carbon that adsorbs fuel therein. The canister 18 is connected to the upper space 10 a of the fuel tank 10 by a discharge passage 20. Fuel vapor is discharged from the upper space 10a of the fuel tank 10 to the canister 18 side through the discharge passage 20.

A blocking valve unit 22 is formed in the middle of the discharge passage 20. The blocking valve unit 22 includes a blocking valve 22a and a relief valve 22b.
The blocking valve 22a is an electromagnetic valve that can be switched between a valve open state and a valve closed state. When the blocking valve 22a is opened, the fuel vapor on the fuel tank 10 side can be discharged to the canister 18 side through the discharge passage 20. When the blocking valve 22a is closed (that is, the fuel tank 10 is closed), it is impossible to discharge the fuel vapor in the fuel tank 10 to the canister 18 via the discharge passage 20.

  That is, even if the fuel tank 10 is indirectly connected to the outside through another path connected to the canister 18, the upper space 10 a of the fuel tank 10 is in an airtight state if the blocking valve 22 a is closed. Will be blocked.

  The relief valve 22b is opened when the difference between the pressure in the discharge passage 20 on the fuel tank 10 side and the pressure in the discharge passage 20 on the canister 18 side is excessive with the block valve unit 22 interposed therebetween.

  Note that an ORVR (On-Board Referencing Vapor Recovery) valve 24 and a rollover valve 26 are provided in the opening of the fuel tank 10 in the discharge passage 20. The ORVR valve 24 opens when the pressure in the fuel tank 10 rises due to a rise in the fuel level accompanying refueling, and the fuel vapor in the fuel tank 10 is sent to the canister 18 side via the discharge passage 20. This suppresses the release of fuel vapor from the fuel inlet pipe 16 and the circulation pipe 16c into the atmosphere during refueling. The rollover valve 26 is closed when the vehicle is largely inclined to prevent liquid fuel from leaking outside.

  The fuel vapor in the fuel tank 10 is generated when the sealing valve unit 22 is in an open state (normally, the sealing valve 22a is open) and at least one of the ORVR valve 24 and the rollover valve 26 is open. It is discharged to the canister 18 side through the discharge passage 20. As a result, the fuel vapor in the fuel tank 10 is adsorbed by the adsorbent in the canister 18.

  Connected to the canister 18 is an air introduction passage 28 communicating with the fuel inlet box 16d. The air introduction passage 28 is provided with an air filter 28a on the way. Further, in the atmosphere introduction passage 28, a CCV (canister atmosphere port closed valve) is switched at a position closer to the canister 18 than the air filter 28a between the cutoff state (valve closed state) and the communication state (valve open state). ) 30 is provided.

  Further, the canister 18 is connected to the intake passage 36 at a position downstream of the throttle valve 34 by the purge passage 32. In the middle of the purge passage 32, a purge control valve 38 is disposed as an electromagnetic valve that can be switched between a valve open state and a valve closed state.

  When the purge control valve 38 is opened, the fuel vapor separated from the adsorbent of the canister 18 can be released into the intake air flowing through the intake passage 36 via the purge passage 32. As a result, the intake air including the purge fuel flowing into the surge tank 40 from the intake passage 36 is distributed to the intake port 6 of each cylinder and burned together with the fuel from the fuel injection valve 8 in the combustion chamber of each cylinder. Become.

  If both the CCV 30 and the purge control valve 38 are closed and the block valve 22a is opened, the fuel supply system 4 may block the compartment including the fuel tank 10 and the canister 18 in an airtight state. It becomes possible. Further, when the CCV 30, the purge control valve 38, and the blocking valve 22a are all closed, the canister 18 can be sealed in an airtight state in the fuel supply system 4 of the internal combustion engine 2.

The CCV 30 is provided with a canister internal pressure sensor 42 for detecting the pressure (canister internal pressure CP) on the canister 18 side.
In the intake passage 36, an air flow meter 46 is provided between the air filter 44 and the throttle valve 34 to detect the intake air amount GA (g / sec) supplied to the internal combustion engine 2.

  In addition, an accelerator opening sensor 48 provided on an accelerator pedal operated by a driver of the vehicle to detect the accelerator opening ACCP, an engine speed sensor 50 for detecting the rotational speed NE of the crankshaft of the internal combustion engine 2, an ignition switch ( IGSW) 52 and other sensors / switches are provided to output signals. Examples of other signals include cooling water temperature, intake air temperature, and vehicle speed.

  Detection signals from the fuel sender gauge 14, the canister internal pressure sensor 42, the air flow meter 46, the accelerator opening sensor 48, the engine speed sensor 50, the IGSW 52, etc. 54).

  Then, based on such signal data and data stored in advance, the ECU 54 executes arithmetic processing to control the mechanisms such as the blocking valve 22a, the CCV 30, the throttle valve 34, and the purge control valve 38. Further, when an abnormality is found by a diagnostic process described later, a process of notifying the driver by lighting a warning lamp 56 on the dashboard is also executed.

  Next, fuel tank leak diagnosis processing and canister leak diagnosis processing in the fuel supply system 4 executed by the ECU 54 will be described. The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

The fuel tank leak diagnosis process is shown in the flowchart of FIG. This process is a process executed at regular intervals when the IGSW 52 is switched off (the internal combustion engine 2 is stopped).
When the IGSW 52 is turned off and the fuel tank leak diagnosis process (FIG. 2) is executed, it is first determined whether or not the fuel tank leak diagnosis execution condition is satisfied (S102).

The fuel tank leak diagnosis execution condition is, for example, the following condition.
1. The rotation of the internal combustion engine 2 is stopped (engine speed NE = 0 rpm).
2. The internal combustion engine 2 has been operated for a predetermined time or more immediately before the operation of the internal combustion engine 2 is stopped.

3. Not refueling.
4). The vehicle speed is 0 km / h.
If any one of these conditions is not satisfied, the fuel tank leak diagnosis execution condition is not satisfied, and if all are satisfied, it is determined that the fuel tank leak diagnosis execution condition is satisfied.

In addition to the conditions 1 to 4, for example, an appropriate range of the cooling water temperature and an appropriate range of the intake air temperature may be added.
If the fuel tank leak diagnosis execution condition is not satisfied (NO in S102), the process is temporarily exited. Thereafter, unless the fuel tank leak diagnosis execution condition is satisfied, the fuel tank leak diagnosis process (FIG. 2) does not perform a substantial process.

  If the fuel tank leak diagnosis execution condition is satisfied (YES in S102), it is next determined whether or not this is the first process when the current fuel tank leak diagnosis execution condition is satisfied (S104).

  If it is the first (YES in S104), the fuel level SGL in the fuel tank 10 currently detected by the fuel sender gauge 14 is read into the memory in the ECU 54 as the initial fuel level SGLini (S106). .

Next, the blocking valve 22a is closed, and the fuel tank 10 is blocked (S108).
Then, it is determined whether or not the elapsed time after the fuel tank 10 has been sealed is equal to or longer than the predetermined time DTa (S110). As the predetermined time DTa, for example, a time in the range of 30 to 60 minutes is set.

In the initial stage, since the elapsed time after the blockade <the predetermined time DTa (NO in S110), the present process is temporarily exited.
If the fuel tank leak diagnosis execution condition is established after the next control cycle, it is determined as YES in step S102, but since it is not the first (NO in S104), the elapsed time immediately after the blockade It is determined whether or not the predetermined time DTa or longer (S110). As long as the elapsed time after the blockade <the predetermined time DTa (NO in S110), the state of exiting the present process continues as it is.

  When the fuel tank leak diagnosis execution condition has been established and the elapsed time after the blockade is equal to or longer than the predetermined time DTa (YES in S110), the fuel liquid in the fuel tank 10 detected by the fuel sender gauge 14 is then detected. The surface level SGL is read into the memory as the fuel liquid surface level SGLa after the predetermined time DTa has elapsed (S112).

  Then, as shown in Expression 1, the liquid level change amount ΔSGL is calculated as an absolute value of the difference between the fuel liquid level SGLa and the initial fuel liquid level SGLini after the predetermined time DTa has elapsed (S114).

[Formula 1] ΔSGL ← | SGLa−SGLini |
Here, since the internal combustion engine 2 has been operated for a predetermined time or more immediately before the operation is stopped, immediately before the operation of the internal combustion engine 2 is stopped, the fuel temperature in the fuel tank 10 including the fuel is higher than the outside air temperature. The fuel tank 10 has risen more than about, and high-pressure fuel vapor corresponding to the fuel temperature was generated in the upper space 10a of the fuel tank 10. In such a fuel vapor pressure state, during operation of the internal combustion engine 2, at least the blocking valve unit 22 and the CCV 30 are open, so the pressure in the upper space 10a of the fuel tank 10 is substantially the same as the external pressure. It was.

  Thus, during operation of the internal combustion engine 2, there is almost no pressure difference due to atmospheric pressure inside and outside the outer shells 10 b and 10 c of the fuel tank 10. There is only a pressure difference corresponding to the weight of the fuel 10d in the lower shell 10b.

  When the fuel tank 10 dissipates heat by stopping the operation of the internal combustion engine 2 and the fuel temperature approaches the outside air temperature, the fuel vapor pressure in the upper space 10a decreases. If the fuel tank 10 is blocked by the fuel tank leak diagnosis process (FIG. 2) when the fuel vapor pressure is reduced, the inside of the fuel tank 10 becomes lower than the outside air pressure and is in a negative pressure state. Therefore, the pressure from the outside toward the inside increases in the outer shells 10b and 10c by the amount of the negative pressure.

  Therefore, the outer shells 10b and 10c are deformed inside the fuel tank 10, respectively. That is, as shown by a broken line in FIG. 1, the lower outline 10b is deformed to warp upward, and the top outline 10c is deformed to warp downward. In addition, since the shape of the fuel tank 10 is likely to cause vertical deformation due to external force at the center position of the outer shells 10b and 10c, compared to the edge of the outer shells 10b and 10c where the fuel sender gauge 14 is disposed, The amount of deformation in the vertical direction increases as the center position is farther from the edge.

  In particular, the lower outer shell 10b is deformed upward to reduce the volume of the storage portion for the fuel 10d. For this reason, the storage amount itself of the fuel 10d in the fuel tank 10 is not changed, but the liquid level slightly rises to push up the float 14a. As described above, the fuel sender gauge 14 is disposed at the edge of the outer shell 10b and is disposed at a position where the fuel sender gauge 14 hardly deforms. Therefore, the rise of the float 14a is detected by the fuel sender gauge 14, and the fuel liquid in the fuel tank 10 is detected. A change in the surface level SGL is detected.

The change in the fuel liquid level SGL is the liquid level change amount ΔSGL obtained by the equation 1.
However, as described above, the negative pressure is generated including the fuel inlet pipe 16 connected to the fuel tank 10, the circulation pipe 16 c, the blocking valve unit 22, and the discharge passage 20 between the blocking valve unit 22 and the fuel tank 10. In this case, there is no leak hole or valve closing failure on the fuel tank 10 side.

  If there is a leak on the side of the fuel tank 10, even if the fuel vapor pressure in the upper space 10a is lowered and a transition is made to a negative pressure state, outside air enters due to the leak and does not reach a sufficiently negative pressure state.

For this reason, at the time of leak abnormality, the liquid level change amount ΔSGL obtained by the equation 1 does not become a sufficiently large value.
Accordingly, it is next determined whether or not the liquid level change amount ΔSGL obtained in step S114 is equal to or larger than the predetermined liquid level change amount Asgl (S116).

  If the liquid level change amount ΔSGL ≧ the predetermined liquid level change amount Asgl (YES in S116), the fuel tank normal determination is made assuming that the upper space 10a of the fuel tank 10 is sufficiently negative (S118).

  However, if the liquid level change amount ΔSGL <the predetermined liquid level change amount Asgl (NO in S116), it is determined that the upper space 10a of the fuel tank 10 is not sufficiently negative and the fuel tank abnormality is determined (S120).

  If any of the determinations (S118, S120) is made, the current fuel tank leak diagnosis process is stopped (S122). Therefore, after that, when the internal combustion engine 2 is operated again and then the IGSW 52 is turned off, the fuel tank leak diagnosis process (FIG. 2) as described above is executed.

  When fuel tank abnormality determination (S120) is made in the fuel tank leak diagnosis process (FIG. 2), a warning lamp 56 on the dashboard is turned on to notify the driver, and a process such as entering the retreat driving mode is separately performed. Done.

FIG. 3 is a timing chart showing an example of control by the fuel tank leak diagnosis process (FIG. 2).
When the IGSW 52 is turned off at timing t0, the ECU 54 starts the fuel tank leak diagnosis process (FIG. 2). When the fuel tank leak diagnosis execution condition described above is satisfied at this start timing, the blocking valve 22a is closed, and the inside of the fuel tank 10 is sealed in an airtight state.

  Thereafter, the tank internal pressure gradually decreases as the fuel vapor pressure decreases as the fuel temperature in the fuel tank 10 decreases as shown by the solid line. Since the fuel tank 10 is in an airtight state, the tank internal pressure becomes lower than the external air pressure.

  Therefore, as shown by the broken line in FIG. 1, the outer shell 10b on the lower side of the fuel tank 10 is deformed so as to warp upward due to the differential pressure between the external air pressure and the tank internal pressure. As a result, the float 14a of the fuel sender gauge 14 rises, and the fuel level SGL detected by the fuel sender gauge 14 gradually increases as the deformation amount of the outer shell 10b increases.

Then, at the timing t1 when the predetermined time DTa has elapsed from the timing t0, the fuel liquid level SGL = SGLa1 is reached.
At this timing t1, the liquid level change amount ΔSGL is calculated as shown in Equation 1 above. If the liquid level change amount ΔSGL ≧ the predetermined liquid level change amount Asgl (YES in S116), it is determined that the fuel tank 10 in the fuel supply system 4 has been kept airtight in the fuel supply system 4, and the fuel tank normality is determined ( S118).

  Consider a case in which the tank internal pressure hardly changes and the outer shell 10b on the lower side of the fuel tank 10 hardly deforms as shown by a one-dot chain line in spite of the closed state of the blocking valve 22a. In this case, at the timing t1 when the predetermined time DTa has elapsed from the timing t0, the fuel liquid level SGL = SGLa2, and hardly changes from the initial fuel liquid level SGLini.

  Therefore, the liquid level change amount ΔSGL <the predetermined liquid level change amount Asgl (NO in S116), and it is determined that there is a leak and the airtight state of the fuel tank 10 is not maintained (S120).

  Next, a canister leak diagnosis process executed by the ECU 54 during operation of the internal combustion engine 2 is shown in the flowchart of FIG. This process is a process executed at regular time intervals when the internal combustion engine 2 is operated.

When the canister leak diagnosis process (FIG. 4) is started, it is first determined whether or not a canister leak diagnosis execution condition is satisfied (S202).
The canister leak diagnosis execution condition is, for example, the following condition.

1. The internal combustion engine 2 is idling and the engine speed NE is stable within a predetermined range.
2. The vehicle speed is 0 km / h.
3. No fuel tank abnormality determination has been made in the fuel tank leak diagnosis process (FIG. 2).

If any one of these conditions is not satisfied, the canister leak diagnosis execution condition is not satisfied, and if all are satisfied, it is determined that the canister leak diagnosis execution condition is satisfied.
In addition to the above conditions 1 to 3, for example, an appropriate range of the cooling water temperature and an appropriate range of the intake air temperature may be added.

  Here, if the canister leak diagnosis execution condition is not satisfied (NO in S202), the present process is temporarily exited. Thereafter, unless the canister leak diagnosis execution condition is satisfied, the canister leak diagnosis process (FIG. 4) does not perform a substantial process.

  If the canister leak diagnosis execution condition is satisfied (YES in S202), it is next determined whether or not the first process is performed when the current canister leak diagnosis execution condition is satisfied (S204).

If it is first (YES in S204), the blocking valve 22a and the CCV 30 are closed, and the canister 18 is shut off from the fuel tank 10 side and the atmosphere side (S206).
Next, the purge control valve 38 is opened for a short time (for example, within 1 min) and then closed (S208). If the purge control valve 38 has already been opened, the purge control valve 38 is closed after the valve opening state is maintained for a short time.

  As a result, the interior of the canister 18 is temporarily connected to the intake passage 36 on the downstream side of the throttle valve 34 with the atmosphere side and the fuel tank 10 side blocked.

  At this timing, since the internal combustion engine 2 is in the idling stable state, the intake passage 36 downstream of the intake air from the throttle valve 34 is sufficiently negative with respect to the external air pressure. Therefore, in the canister 18, gas is sucked from the intake passage 36 side, that is, negative pressure is introduced in a state where no gas is introduced from the discharge passage 20 or the air introduction passage 28. Since the purge control valve 38 is closed after the inside of the canister 18 is in the negative pressure state in this way, the inside of the canister 18 is maintained in the negative pressure state.

  In this state, the canister internal pressure CP, which is the pressure in the canister 18 detected by the canister internal pressure sensor 42, is read into the memory in the ECU 54 as the initial canister internal pressure CPini (S210).

  Then, it is determined whether or not the elapsed time after the inside of the canister 18 is in a negative pressure state is equal to or longer than the predetermined time DTb (S212). As this predetermined time DTb, a time in the range of several minutes, for example, 2 to 6 min is set.

Initially, since elapsed time <predetermined time DTb (NO in S212), the present process is temporarily exited.
If the canister leak diagnosis execution condition has been established after the next control cycle, it is determined YES in step S202, but since it is not the first (NO in S204), is the elapsed time immediately greater than or equal to the predetermined time DTb? It is determined whether or not (S212). As long as the elapsed time after the blockade <the predetermined time DTb (NO in S212), the state of exiting the present process once continues.

  If the elapsed time becomes equal to or longer than the predetermined time DTb in the state where the canister leak diagnosis execution condition has been satisfied (YES in S212), the canister internal pressure CP detected by the canister internal pressure sensor 42 is set to a value after the predetermined time DTb has elapsed. The canister internal pressure CPa is read into the memory (S214).

  Then, the canister internal pressure change amount ΔCP is calculated as a value obtained by subtracting the initial canister internal pressure CPini from the canister internal pressure CPa after the lapse of the predetermined time DTb as shown in Expression 2 (S216).

[Formula 2] ΔCP ← CPa − CPini
If there is no leak on the canister 18 side, the canister internal pressure CP should hardly change from the initial canister internal pressure CPini even after the predetermined time DTb has elapsed. However, if there is a leak, the gas has entered and should have risen to some extent from the initial canister internal pressure CPini.

Therefore, it is determined whether or not the canister internal pressure change amount ΔCP obtained by the equation 2 is equal to or smaller than the predetermined canister internal pressure change amount Acp (S218).
If canister internal pressure change amount ΔCP ≦ predetermined canister internal pressure change amount Acp (YES in S218), it is determined that the negative pressure state in canister 18 is sufficiently maintained, that is, there is no leak, and canister normality is determined ( S220).

  However, if the canister internal pressure change amount ΔCP> predetermined canister internal pressure change amount Acp (NO in S218), it is determined that the negative pressure state in the canister 18 is not sufficiently maintained, that is, a leak exists, and a canister abnormality determination is made. (S222).

  If any of the determinations (S220, S222) is made, the current canister leak diagnosis process is stopped (S224). Therefore, after that, when the canister leak diagnosis execution condition is newly established, the canister leak diagnosis process (FIG. 4) as described above is executed.

When the canister abnormality determination (S222) is made, processing such as turning on the warning lamp 56 on the dashboard to notify the driver and entering the retreat travel mode is separately performed.
FIG. 5 is a timing chart showing an example of control by canister leak diagnosis processing (FIG. 4).

  At timing t10, the canister leak diagnosis execution condition is established, and the blocking valve 22a and the CCV 30 are closed. At this timing, since the purge control valve 38 is still open, the canister internal pressure CP decreases as shown by the solid line. Then, the purge control valve 38 is closed at a timing t11 after a short time.

  By such a temporary introduction of negative pressure into the canister 18, the canister internal pressure CP is lowered and maintained as it is. At timing t11, the canister internal pressure CPini1 detected by the canister internal pressure sensor 42 is stored.

The canister internal pressure CPa1 detected by the canister internal pressure sensor 42 at the timing t12 after the predetermined time DTb has elapsed is stored.
Then, the canister internal pressure change amount ΔCP (= CPa1−CPini1) is calculated as shown in the equation (2).

  In the solid line, since there is no leak in the canister 18, the intake negative pressure introduced from the intake passage 36 side is sufficiently maintained for the predetermined time DTb. Therefore, canister internal pressure change amount ΔCP ≦ predetermined canister internal pressure change amount Acp is satisfied (YES in S218), and canister normality determination is made (S220).

  When there is a leak in the canister 18, when a negative pressure is introduced from the intake passage 36 side, the inside of the canister 18 temporarily decreases to the canister internal pressure CPini 2 (t 10 to t 11) as indicated by a one-dot chain line. However, although the purge control valve 38 is closed at the timing t11, the canister internal pressure CP subsequently increases due to leakage.

The canister internal pressure CPa2 detected by the canister internal pressure sensor 42 is stored at timing t12 after the predetermined time DTb has elapsed.
Then, the canister internal pressure change amount ΔCP (= CPa2−CPini2) is calculated as shown in the equation (2).

  If there is a leak, as indicated by the alternate long and short dash line, the canister internal pressure CPa2 is sufficiently high after the predetermined time DTb has elapsed, and the canister internal pressure change amount ΔCP> the predetermined canister internal pressure change amount Acp (NO in S218). Therefore, a canister abnormality determination is made (S222).

  In the above-described configuration, the relationship with the claims corresponds to the ECU 54 as a fuel supply system leak diagnosis device. Of the control executed by the ECU 54, the fuel tank leak diagnosis process (FIG. 2) corresponds to a process as a fuel supply system leak detection method.

  The sealing valve 22a corresponds to the sealing means, and the fuel sender gauge 14 corresponds to the deformation amount detecting means. Steps S104 to S120 of the fuel tank leak diagnosis process (FIG. 2) correspond to the process as the leak determination means.

According to the first embodiment described above, the following effects can be obtained.
(1) When a pressure difference is generated between the inside and the outside of the compartment in the fuel supply system 4, which is sealed in an airtight state by the sealing valve 22a, here, the force to the outside or the inside acts. Thus, the outer shells 10b and 10c are deformed according to the pressure difference. In particular, the lower outer shell 10b, which has a flat plate shape with a large area compared to other portions, has low rigidity due to its shape, and thus is likely to be greatly deformed.

  For this reason, in the fuel tank leak diagnosis process (FIG. 2), the fuel tank 10 is sealed in an airtight state by the sealing valve 22a, and then the deformation amount of the outer shell 10b is determined by the fuel sender gauge 14 as the amount of change in the fuel liquid level SGL. By detecting, the leak determination in the fuel tank 10 is executed.

  Such leak detection based on the deformation amount of the outer shell 10b is not based only on the pressure inside the outer shell 10b but based on the pressure difference between the outer and inner portions of the outer shell 10b. From this, compared with the prior art which detects only the pressure inside the outer shell 10b, in the present embodiment, the detection result appropriately reflects the internal / external pressure relationship. Therefore, the leak detection becomes highly accurate, and the fuel tank leak diagnosis process (FIG. 2) enables accurate leak determination.

  (2) The amount of deformation of the outer shell 10b is detected by the fuel sender gauge 14 after a predetermined time DTa has elapsed, particularly after the fuel tank 10 has been sealed. Thus, by allowing the DTa to elapse for a predetermined time after the blockage, the fuel vapor pressure can be sufficiently lowered, and a reliable leak determination can be performed.

  (3) In the leak determination, it is determined whether or not the predetermined liquid level change amount Asgl or more. That is, when the deformation amount of the outer shell 10b is larger than the predetermined deformation amount, it is determined that there is no leak and the fuel tank is normal. From this, it is possible to determine whether the fuel tank is normal in a sufficiently reliable deformation amount state.

  (4) The outer shells 10 b and 10 c of the fuel tank 10 are larger in area than the other parts in the fuel supply system 4. For this reason, the pressure difference between the inside and outside of the section for determining the leak is amplified and appears in the deformation amount. Therefore, even if the amount of deformation of the outer shell 10b of the fuel tank 10 is detected, it is possible to determine the leak of the compartment including the fuel tank 10 with high accuracy.

In particular, the lower outer shell 10b is a portion that is easily deformed due to the internal / external pressure difference even within the outer shell of the fuel tank 10 as described above, so that the leakage of the compartment can be determined with higher accuracy.
(5) Since the deformation amount of the lower outer shell 10b appears in the fuel liquid level SGL, the outer deformation amount of the fuel tank 10 can be easily detected by the fuel sender gauge 14 provided in the fuel tank 10. That is, a conventional fuel meter can also be used as the deformation amount detecting means.

Therefore, it is not necessary to provide a new mechanism for detecting the amount of deformation of the outer shell of the fuel tank 10, which can contribute to reducing the weight and cost of the vehicle.
In particular, the fuel sender gauge 14 is arranged at a portion (high-rigidity portion) that is difficult to deform and is separated from the center position of the lower outer shell 10b, which is an easily deformable portion, here, an edge of the lower outer shell 10b. Thus, even if the lower shell 10b is deformed, the position of the fuel sender gauge 14 is sufficiently maintained, and the change in the fuel liquid level SGL can be accurately measured.

  (6) The start of execution of the fuel tank leak diagnosis process (FIG. 2) is when the operation of the internal combustion engine 2 is stopped. Accordingly, the leak determination can be performed in a state where the fuel supply system 4 is extremely stable without any disturbance such as the drive vibration of the internal combustion engine 2, so that a more accurate leak determination can be performed.

  (7) The fuel tank leak diagnosis process (FIG. 2) described above does not reduce the pressure in the fuel tank 10 by a pump or the like. Therefore, an expensive device such as a pump module for leak detection is unnecessary. This will not increase costs and increase vehicle weight. In addition, since it is not necessary to detect the abnormality of the pump module itself, the leak diagnosis process itself is simplified, and the processing load on the ECU 54 can be reduced.

  (8) For the canister 18, a canister leak diagnosis process (FIG. 4) using the canister internal pressure sensor 42 is executed. In the canister leak diagnosis process (FIG. 4), the intake passage 36 is operated during operation of the internal combustion engine 2. The leak is judged by introducing the intake negative pressure generated in the engine.

Therefore, the leak diagnosis process for the canister 18 does not require an expensive device such as a pump module, and can easily perform a leak diagnosis with a simple configuration.
[Embodiment 2]
In the present embodiment, steps S116 to S122 in the fuel tank leak diagnosis process shown in FIG. 2 are performed as shown in FIG. Other configurations are the same as those in the first embodiment. Therefore, for the same configuration, the configuration of the first embodiment is referred to.

The fuel tank leak diagnosis process will be described with reference to FIGS.
Steps S102 to S116 are as described in the first embodiment. When the liquid level change amount ΔSGL is calculated by the equation 1 in step S114, it is determined whether or not the liquid level change amount ΔSGL is equal to or larger than a predetermined liquid level change amount Asgl (S116).

  If ΔSGL ≧ Asgl (YES in S116), it is determined that the fuel tank is normal (S118) as in the first embodiment, and the fuel tank leak diagnosis process is stopped (S122).

  If ΔSGL <Asgl (NO in S116), it is determined whether or not the liquid level change amount ΔSGL is equal to or smaller than a predetermined liquid level change amount Lsgl (S117). The predetermined liquid level change amount Lsgl is a value smaller than the predetermined liquid level change amount Asgl, and is a value for determining whether the deformation amount of the outer shell 10b is small or not deformed.

  Here, if ΔSGL> Lsgl (NO in S117), the fuel tank leak diagnosis process is stopped without determining whether the fuel tank is normal or abnormal in the fuel tank (S122).

If ΔSGL ≦ Lsgl (YES in S117), a fuel tank abnormality determination is made (S120), and the fuel tank leak diagnosis process is stopped (S122).
In other words, in the present embodiment, in the state of Asgl>ΔSGL> Lsgl, the fuel tank leak diagnosis process ends without performing a leak diagnosis finally. Therefore, the diagnosis is maintained as data that cannot be diagnosed, and it is determined again whether or not the fuel tank 10 is in the leak state when the next fuel tank leak diagnosis execution condition is satisfied.

In the above-described configuration, the relationship with the claims corresponds to steps S104 to S120 of the fuel tank leak diagnosis processing (FIGS. 2 and 6) as processing as the leak determination means.
According to the second embodiment described above, the following effects can be obtained.

  (1) If it is not possible to make a clear determination, it is determined that the fuel tank 10 is in a leak state again when the next fuel tank leak diagnosis execution condition is satisfied because the diagnosis is impossible. This makes it possible to more accurately determine whether there is a leak. Except for this, the same effects as in the first embodiment are produced.

[Embodiment 3]
In the present embodiment, steps S116 to S122 in the fuel tank leak diagnosis process shown in FIG. 2 are performed as shown in FIG. Other configurations are the same as those in the first embodiment. Therefore, for the same configuration, the configuration of the first embodiment is referred to.

The fuel tank leak diagnosis process will be described with reference to FIGS. Steps S102 to S116 are as described in the first embodiment.
When the liquid level change amount ΔSGL is calculated in step S114, it is determined whether or not the liquid level change amount ΔSGL is equal to or larger than a predetermined liquid level change amount Asgl (S116).

  If ΔSGL ≧ Asgl (YES in S116), it is determined that the fuel tank is normal (S118) as in the first embodiment, and the fuel tank leak diagnosis process is stopped (S122).

  If ΔSGL <Asgl (NO in S116), the elapsed time count after the blockade is canceled (S317). That is, the elapsed time count value after the blockage is returned to 0 and counting is started. Therefore, the determination in step S110 shown in FIG. 2 is again determined as the elapsed time after the blockade <the predetermined time DTa.

Then, it is determined whether or not the number of cancellations is equal to or greater than the predetermined number Y (S318). As the predetermined number Y, for example, 2 to 10 times is set.
If it is the first elapsed time count cancellation, the number of cancellations is one (NO in S318), so the process is temporarily exited.

  In the next control cycle, if the fuel tank leak diagnosis execution condition is continuously satisfied (YES in S102), it is not the first (NO in S104), and then the elapsed time after the blockade is predetermined in step S110. It is determined whether or not the time is DTa or more. Since the elapsed time count value after the block has just been cleared as described above (NO in S110), the present process is temporarily exited. Thereafter, the state determined as NO in step S110 continues until the elapsed time count again reaches the predetermined time DTa or more.

  When the elapsed time count ≧ the predetermined time DTa is satisfied again (YES in S110), the fuel liquid level SGLa at this timing is read (S112), and the liquid level change amount ΔSGL is calculated by Equation 1 (S114).

  Then, it is determined whether or not the liquid level change amount ΔSGL is equal to or larger than a predetermined liquid level change amount Asgl (S116). If ΔSGL ≧ Asgl is satisfied this time (YES in S116), it is determined that the fuel tank is normal (S118), and the fuel tank leak diagnosis process is stopped (S122).

  If ΔSGL <Asgl again this time (NO in S116), as described above, the elapsed time count after the blockade is canceled (S317), and it is determined whether or not the number of cancellations is equal to or greater than the predetermined number Y (S318). .

  If cancel count <predetermined count Y (NO in S318), the process waits again until the elapsed time count becomes equal to or greater than the predetermined time DTa as described above. If the elapsed time count is equal to or greater than the predetermined time DTa (YES in S110), the fuel liquid level SGLa at that timing is read (S112), and the liquid level change amount ΔSGL according to the equation 1 is calculated (S114). It is determined whether or not the surface change amount ΔSGL ≧ the predetermined liquid surface change amount Asgl (S116).

If ΔSGL ≧ Asgl is satisfied this time (YES in S116), it is determined that the fuel tank is normal (S118), and the fuel tank leak diagnosis process is stopped (S122).
If ΔSGL <Asgl also this time (NO in S116), the elapsed time count after the blockade is canceled as described above (S317), and it is determined whether or not the cancel count is equal to or greater than the predetermined count Y (S318). ).

  If the number of cancellations is equal to or greater than the predetermined number of times Y (YES in S318), the fuel tank is sufficiently fueled even if a period of “predetermined number of times Y × predetermined time DTa” elapses after the fuel tank leak diagnosis execution condition is satisfied. That is, no deformation of 10 occurred. Therefore, it is determined that there is a leak, a fuel tank abnormality determination is made (S120), and the fuel tank leak diagnosis process is stopped (S122).

  When the fuel tank abnormality determination (S120) is made in this way, the warning lamp 56 on the dashboard is turned on to notify the driver, and processing such as entering the retreat travel mode is separately performed.

  In the above-described configuration, the relationship with the claims corresponds to the processing as the leakage determination means in steps S104 to S120, S317, and S318 of the fuel tank leak diagnosis processing (FIGS. 2 and 7).

According to the third embodiment described above, the following effects can be obtained.
(1) In a state where the value of the liquid level change amount ΔSGL representing the deformation amount of the outer shell 10b of the fuel tank 10 cannot be clearly determined, it is possible to accurately determine whether or not there is a leak by waiting again for a predetermined time DTa. Moreover, if the value of the liquid level change amount ΔSGL is equal to or greater than the predetermined liquid level change amount Asgl, the leak diagnosis can be completed as soon as possible by immediately determining that there is no leak. Except for this, the same effects as in the first embodiment are produced.

[Embodiment 4]
In the present embodiment, the canister leak diagnosis process of FIG. 8 is executed at regular intervals during the operation of the internal combustion engine 2 instead of the canister leak diagnosis process (FIG. 4). Since the canister leak diagnosis process of FIG. 8 does not use the canister internal pressure sensor 42, the canister internal pressure sensor 42 does not exist in FIG. Other configurations are the same as those of the first embodiment. Therefore, for the same configuration, the configuration of the first embodiment is referred to.

The canister leak diagnosis process (FIG. 8) will be described. When the process is started, it is first determined whether or not a canister leak diagnosis execution condition is satisfied (S402).
The canister leak diagnosis execution condition is as described in step S202 of FIG. 4. If one of these conditions is not satisfied, the canister leak diagnosis execution condition is not satisfied, and if all of the conditions are satisfied, the canister leak diagnosis execution condition is satisfied. It is determined that the leak diagnosis execution condition is satisfied.

  If the canister leak diagnosis execution condition is not satisfied (NO in S402), the present process is temporarily exited. Thereafter, unless the canister leak diagnosis execution condition is satisfied, the canister leak diagnosis process (FIG. 8) does not perform a substantial process.

  If the canister leak diagnosis execution condition is satisfied (YES in S402), it is next determined whether or not this is the first process when the present canister leak diagnosis execution condition is satisfied (S404).

  If it is the first (YES in S404), the fuel level SGL in the fuel tank 10 currently detected by the fuel sender gauge 14 is read into the memory in the ECU 54 as the initial fuel level SGLini (S406). .

  Then, the CCV 30 is closed (S408), and the blocking valve 22a and the purge control valve 38 are opened (S410). As a result, the introduction of air into the fuel supply system 4 is blocked, and only negative pressure is introduced from the intake passage 36.

  It is determined whether or not the elapsed time is equal to or longer than the predetermined time DTc in this negative pressure introduction state (S412). As this predetermined time DTc, a time in the range of several minutes, for example, 2 to 6 min is set.

In the initial stage, since elapsed time <DTc (NO in S412), the present process is temporarily exited.
If the canister leak diagnosis execution condition has been established after the next control cycle, it is determined as YES in step S402, but since it is not the first (NO in S404), is the elapsed time immediately greater than or equal to the predetermined time DTc? It is determined whether or not (S412). As long as the elapsed time after the introduction of the negative pressure is less than DTc (NO in S412), the state of exiting this process continues as it is.

  If the elapsed time becomes equal to or longer than the predetermined time DTc while the canister leak diagnosis execution condition is satisfied (YES in S412), the fuel liquid level SGL detected by the fuel sender gauge 14 at this timing is set to the predetermined time DTc. The subsequent fuel liquid level SGLc is read into the memory (S414).

  Then, the liquid level change amount ΔSGLc is calculated as a value obtained by subtracting the initial fuel liquid level SGLini from the fuel liquid level SGLc after the predetermined time DTc has elapsed as shown in Expression 3 (S416).

[Formula 3] ΔSGLc ← SGLc − SGLini
At the time of executing this canister leak diagnosis process (FIG. 8), it is already diagnosed that there is no leak on the fuel tank 10 side by the fuel tank leak diagnosis process (FIG. 2). Therefore, if there is no leak on the canister 18 side during the execution of the canister leak diagnosis process (FIG. 8), the canister internal pressure and the fuel tank internal pressure linked thereto are introduced by the negative pressure from the intake passage 36 after the lapse of the predetermined time DTc. There should be some pressure drop. However, if there is a leak in the canister 18, the pressure drop hardly occurs.

Accordingly, it is next determined whether or not the liquid level change amount ΔSGLc obtained by the equation 3 is equal to or larger than the predetermined liquid level change amount Csgl (S418).
If the liquid level change amount ΔSGLc ≧ the predetermined liquid level change amount Csgl (YES in S418), it is determined that the inside of the fuel tank 10 and the canister 18 are sufficiently negative pressure (S420).

  However, if the liquid level change amount ΔSGLc <the predetermined liquid level change amount Csgl (NO in S418), it is determined that the inside of the fuel tank 10 and the canister 18 has not been sufficiently negatively pressured, and a canister abnormality determination is made (S422).

  If any of the determinations (S420, S422) is made, the process is stopped (S424). Therefore, after that, when the canister leak diagnosis execution condition is newly established again, the canister leak diagnosis process (FIG. 8) as described above is executed.

When the canister abnormality determination (S422) is made, processing such as turning on the dashboard warning lamp 56 to notify the driver and entering into the retreat travel mode is separately performed.
FIG. 9 is a timing chart showing an example of control by canister leak diagnosis processing (FIG. 8).

  At timing t20, the canister leak diagnosis execution condition is established, and the initial fuel liquid level SGLini is read from the fuel sender gauge 14. The CCV 30 is closed while the blocking valve 22a and the purge control valve 38 are open. Therefore, by introducing the intake negative pressure, the canister internal pressure and the fuel tank internal pressure decrease as indicated by the solid line.

  Then, at the timing t21 after the elapse of the predetermined time DTc, the fuel liquid level SGLc1 detected by the fuel sender gauge 14 is read, and the liquid level change amount ΔSGLc is calculated as shown in the above equation 3.

  In the solid line, since there is no leak in the canister 18, the inside of the canister 18 and the fuel tank 10 is sufficiently made negative by the intake negative pressure introduced from the intake passage 36 side. Therefore, the liquid level change amount ΔSGLc ≧ the predetermined liquid level change amount Csgl is satisfied (YES in S418), and the canister normality determination is made (S420).

When there is a leak in the canister 18, the internal pressure is not sufficiently reduced as indicated by the alternate long and short dash line even if the intake negative pressure is introduced from the intake passage 36 side.
Then, at the timing t21 after the lapse of the predetermined time DTc, the fuel liquid level SGLc2 detected by the fuel sender gauge 14 is read, and based on this value, the liquid level change amount ΔSGLc is calculated as shown in the equation 3. Is done.

  If there is a leak, the fuel liquid level SGLc2 after the predetermined time DTc elapses as indicated by the alternate long and short dash line, the liquid level change amount ΔSGLc <the predetermined liquid level change amount Csgl (NO in S418). Therefore, a canister abnormality determination is made (S422).

  In the configuration described above, the relationship with the claims is that the purge passage 32 is the pressure introduction passage, the CCV 30 is the sealing means, and the fuel sender gauge 14 is the deformation amount detection means, in addition to the correspondence described in the first embodiment. Further, steps S404 to S422 of the canister leak diagnosis process (FIG. 8) correspond to the process as the leak determination means.

According to the fourth embodiment described above, the following effects can be obtained.
(1) The effects (1) to (7) of the first embodiment are produced.
(2) For the canister 18, leak determination is performed by introducing intake negative pressure generated in the intake passage 36 during operation of the internal combustion engine 2 by canister leak diagnosis processing (FIG. 8).

  Moreover, unlike the canister leak diagnosis process (FIG. 4) described in the first embodiment, the canister internal pressure sensor 42 is not used. Similar to the fuel tank leak diagnosis process (FIG. 2), the leak is detected by the liquid level change amount ΔSGLc detected by the fuel sender gauge 14, that is, the deformation amount of the fuel tank 10.

  For this reason, the effects of (1) to (5) and (7) described in the first embodiment can also be produced in the leak diagnosis of the canister 18 by the canister leak diagnosis process (FIG. 8).

[Embodiment 5]
In the first, second, and fourth embodiments, the predetermined time DTa used in FIG. 2 and its modification (FIG. 6) is the length of the operation period immediately before the stop of the internal combustion engine 2 as shown in FIG. You may adjust according to the magnitude | size of the integrated rotation speed immediately before the stop of the internal combustion engine 2. FIG.

  Further, here, since the internal combustion engine 2 is for driving the vehicle, the predetermined time DTa is set to the length of the vehicle travel period immediately before the stop of the internal combustion engine 2 or immediately before the stop of the internal combustion engine 2 as shown in FIG. You may adjust according to the length of vehicle travel distance.

  In the fuel supply system 4, the pressure difference between the outside and the outside of the compartment sealed in an airtight state as described above tends to increase especially when the temperature of the internal combustion engine 2 is stopped, particularly as the temperature decreases. The temperature of the fuel supply system 4 when the internal combustion engine 2 is stopped depends on the length of the operation period of the internal combustion engine 2 immediately before the stop of the internal combustion engine 2 or the magnitude of the integrated rotational speed.

  When the internal combustion engine 2 is mounted on a vehicle for driving the vehicle, the temperature of the fuel supply system 4 when the internal combustion engine 2 is stopped is the length of the vehicle traveling period immediately before the internal combustion engine 2 is stopped. Or depending on the length of the vehicle mileage.

  Therefore, as shown in FIGS. 10A and 10B, the predetermined time DTa is set according to the length of the operation period immediately before the internal combustion engine 2 is stopped or the accumulated rotational speed immediately before the internal combustion engine 2 is stopped, or Adjustment is made according to the length of the vehicle traveling period or the length of the vehicle traveling distance immediately before the stop of the internal combustion engine 2.

  Specifically, as the value of the length of the driving period, the total number of revolutions, the length of the vehicle traveling period, or the length of the vehicle traveling distance increases, the predetermined time DTa is decreased to detect leaks at an early stage. is doing.

By adjusting the leak detection timing in this way, it is possible to make a leak diagnosis as early as possible while ensuring the leak detection accuracy.
[Embodiment 6]
The predetermined number of times Y in FIG. 7 of the third embodiment is set to the length of the operation period immediately before the stop of the internal combustion engine 2 or the integrated rotation immediately before the stop of the internal combustion engine 2 as shown in FIGS. You may adjust according to the magnitude | size of a number, or according to the length of the vehicle travel period, or the length of the vehicle travel distance immediately before the internal combustion engine 2 stops.

Specifically, the predetermined number of times Y is reduced as the value of the length of the driving period, the accumulated rotational speed, the length of the vehicle traveling period, or the length of the vehicle traveling distance increases.
By adjusting the leak detection timing in this way, it is possible to make a leak diagnosis as early as possible while ensuring the leak detection accuracy.

[Embodiment 7]
In each of the embodiments described above, the deformation amount in the outer shell 10b on the lower side of the fuel tank 10 is detected as the fuel liquid level SGL by the fuel sender gauge 14 as shown in FIG.

  In addition to this, as shown in FIG. 12 (a), a contact type displacement sensor 60 such as a contact switch is not used in the fuel sender gauge 14, but a configuration other than the fuel tank 10, for example, an underfloor panel 62 of the vehicle body. The amount of deformation of the outer shell 10c of the fuel tank 10 may be detected by providing the contact 60a with the outer shell 10c of the fuel tank 10.

  In a situation where the pressure in the upper space 10a of the fuel tank 10 decreases and the pressure difference between the inside and outside of the outer shell 10c increases, the switch is turned off (or turned on) when the outer shell 10c is separated from the contact 60a, and the amount of deformation is sufficient. Is generated in the outer shell 10c, and it can be determined that there is no leak.

  On the other hand, even when the pressure in the upper space 10a should decrease, if the outer shell 10c does not leave the contact 60a and the switch remains on (or off), a sufficient amount of deformation occurs in the outer shell 10c. It can be determined that there is a leak.

The contact of the displacement sensor 60 may not be brought into contact with the outer shell 10c at the top of the fuel tank 10, but may be brought into contact with the lower outer shell 10b.
As shown in FIG. 12B, a non-contact type displacement sensor 64 may be disposed on the under floor panel 62 of the vehicle body to detect deformation of the outer shell 10c. For example, infrared rays, laser light, or ultrasonic waves are radiated from the displacement sensor 64 to the outer shell 10c, and a change in the distance between the non-contact type displacement sensor 64 and the outer shell 10c is measured based on the reception timing of the reflected light or reflected sound. The deformation amount 10c may be detected.

Note that the non-contact type displacement sensor 64 may be disposed facing the lower side of the fuel tank 10 to detect the deformation amount of the lower shell 10b.
As shown in FIG. 12C, the deformation amount of the outer shell 10c of the fuel tank 10 is detected by affixing the strain gauge 66 on the outer side of the outer shell 10c and detecting the strain generated corresponding to the deformation of the outer shell 10c. You may do it.

The strain gauge 66 may be attached to the outside of the lower shell 10b of the fuel tank 10 to detect the deformation amount of the lower shell 10b.
[Embodiment 8]
A fuel tank leak diagnosis process shown in FIG. 13 may be executed instead of the fuel tank leak diagnosis process (FIG. 2) of the first embodiment or in addition to the fuel tank leak diagnosis process (FIG. 2). Other configurations are the same as those in the first embodiment. Therefore, for the same configuration, the configuration of the first embodiment is referred to.

  The fuel tank leak diagnosis process (FIG. 13) will be described. This process determines whether or not there is a leak according to a change in the outside air temperature while the internal combustion engine 2 is stopped, and is a process that is executed at regular intervals when the IGSW 52 is switched off.

When this process is started, it is first determined whether or not the fuel tank leak diagnosis execution condition in this process is satisfied (S502).
The fuel tank leak diagnosis execution condition is, for example, the following condition.

1. The rotation of the internal combustion engine 2 is stopped (engine speed NE = 0 rpm).
2. Not refueling.
3. The vehicle speed is 0 km / h.

4). Whether the stop state of the internal combustion engine 2 continues for a predetermined time (a period in which the fuel temperature is made equal to the outside air temperature: for example, 5 hours).
If any one of these conditions is not satisfied, the fuel tank leak diagnosis execution condition is not satisfied, and if all are satisfied, it is determined that the fuel tank leak diagnosis execution condition is satisfied.

  If the fuel tank leak diagnosis execution condition is not satisfied (NO in S502), the present process is temporarily exited. Thereafter, unless the fuel tank leak diagnosis execution condition is satisfied, the fuel tank leak diagnosis process (FIG. 13) does not perform substantial processing.

  If the fuel tank leak diagnosis execution condition is satisfied (YES in S502), it is next determined whether or not this is the first process when the current fuel tank leak diagnosis execution condition is satisfied (S504).

If it is the first time (YES in S504), the blocking valve 22a is closed (S506). If the blocking valve 22a is already closed, that state is maintained.
Then, the fuel level SGL in the fuel tank 10 currently detected by the fuel sender gauge 14 is read into the memory in the ECU 54 as the initial fuel level SGLini (S508).

  Then, it is determined whether or not the outside air temperature has changed by a predetermined temperature range since the present fuel tank leak diagnosis execution condition is satisfied (S510). The outside air temperature is based on the intake air temperature signal read by the ECU 54. The predetermined temperature range is set such that the fuel vapor pressure changes to some extent and affects the fuel liquid level SGL in the fuel tank 10.

If the outside air temperature has not changed by the predetermined temperature range (NO in S510), the present process is temporarily exited.
After the next control cycle, if the fuel tank leak diagnosis execution condition has been established, it is determined YES in step S502, but since it is not the first (NO in S504), the outside air temperature immediately becomes the predetermined temperature. It is determined whether or not the width has changed (S510). As long as the outside air temperature does not change by a predetermined temperature range (NO in S510), the state of exiting the present process continues as it is.

  If the outside air temperature changes by a predetermined temperature range with the fuel tank leak diagnosis execution condition being established (YES in S510), the fuel level level SGL in the fuel tank 10 detected by the fuel sender gauge 14 is then set. Then, the fuel liquid level SGLt after the change in the predetermined temperature range is read into the memory (S512).

  Then, the liquid level change amount ΔSGLt is calculated as an absolute value of the difference between the fuel liquid level SGLt and the initial fuel liquid level SGLini after the predetermined temperature range change as shown in Expression 4 (S514).

[Formula 4] ΔSGLt ← || SGLt − SGLini |
Here, when the fuel tank leak diagnosis execution condition is satisfied, a sufficient time has elapsed since the internal combustion engine 2 was stopped, and the fuel temperature in the fuel tank 10 is made equal to the outside air temperature. In the airtight fuel tank 10 in this state, the fuel temperature changes in conjunction with the subsequent change in the outside air temperature, and the vapor pressure changes corresponding to the fuel temperature change.

  Therefore, for example, if the outside air temperature rises by a predetermined temperature range, the fuel tank internal pressure is increased corresponding to the predetermined temperature range, and if the outside air temperature falls by a predetermined temperature range, the fuel tank internal pressure is decreased corresponding to the predetermined temperature range.

  This high pressure or low pressure causes the outer shell 10b of the fuel tank 10 to be deformed, and changes the fuel level SGL detected by the fuel sender gauge 14. When the pressure is increased, the outer shell 10b warps outward, so that the lower volume of the fuel tank 10 increases and the fuel liquid level SGL decreases. On the contrary, when the pressure is reduced, the outer shell 10b warps inward, so that the lower volume of the fuel tank 10 decreases and the fuel liquid level SGL increases.

The change in the fuel liquid level SGL is the liquid level change amount ΔSGLt obtained by the equation 4.
However, as described above, the change in the internal pressure of the fuel tank occurs because the configuration on the fuel tank 10 side (the configuration in which the fuel tank 10 and the fuel tank 10 are sealed in an airtight state), a hole that causes a leak, a poor valve closing, etc. This is the case when there is no.

  If there is a leak in the configuration on the fuel tank 10 side, even if the upper space 10a attempts to increase or decrease pressure due to the change in fuel vapor pressure, gas flows to the outside through the hole or defective valve closing portion. The fuel tank internal pressure does not change sufficiently.

  For this reason, if there is no leak, the liquid level change amount ΔSGLt obtained by the equation 4 is a sufficiently large value, but if there is a leak, the liquid level change amount ΔSGLt is not a sufficiently large value.

Therefore, it is determined whether or not the liquid level change amount ΔSGLt obtained by the equation 4 is equal to or larger than the predetermined liquid level change amount Tsgl (S516).
If the liquid level change amount ΔSGLt ≧ the predetermined liquid level change amount Tsgl (YES in S516), it is determined that the pressure change corresponding to the change in the outside air temperature has occurred in the fuel tank 10, and the fuel tank normality determination is made (S518). .

  However, if the liquid level change amount ΔSGLt <the predetermined liquid level change amount Tsgl (NO in S516), it is determined that the fuel tank 10 has not sufficiently changed the pressure in accordance with the change in the outside air temperature, and the fuel tank abnormality determination is made. (S520).

  If any of the determinations (S518, S520) is made, the process is stopped (S522). Therefore, thereafter, the fuel tank leak diagnosis process (FIG. 13) as described above is executed again at the timing when the internal combustion engine 2 is stopped after the internal combustion engine 2 is operated.

  Note that when the fuel tank abnormality determination (S520) is made, a process such as turning on the dashboard warning lamp 56 to notify the driver and entering into the retreat travel mode is the same as in the first embodiment. It is.

According to the eighth embodiment described above, the following effects can be obtained.
(1) In addition to the effects associated with the configuration corresponding to the first embodiment, by executing the fuel tank leak diagnosis process (FIG. 13), it is possible to increase the chances of performing accurate leak diagnosis, and the leak abnormality Can be detected quickly.

[Other embodiments]
-In the structure of this invention, an air pump is not essential. Therefore, in each of the above-described embodiments, an example is shown in which the leak diagnosis of the fuel supply system 4 including the fuel tank 10 and the canister 18 is executed without using an air pump. However, a positive pressure or a negative pressure is introduced into the airtight fuel supply system 4 using an air pump, and the fuel supply system 4 is pressurized or depressurized. You may make a leak diagnosis.

  Providing the air pump in this way makes it possible to perform leak diagnosis by reducing or pressurizing the inside of the fuel supply system 4 regardless of whether the internal combustion engine 2 is stopped or driven, thereby increasing the chance of leak diagnosis.

  When detecting the deformation of the outer shells 10b and 10c of the fuel tank 10 as in the seventh embodiment, the deformation measurement site may be made of a configuration or material that can be easily deformed positively by the internal / external pressure difference.

  For example, as shown in FIG. 14A, a bellows-like high stretchable part 70 may be formed in a part of the outer shell 10c, and the position of the tip part 70a may be detected by the displacement sensor 72. Depending on the internal / external pressure difference of the outer shell 10c, the high expansion / contraction portion 70 is deformed by expansion / contraction to a greater extent than the outer shell 10c itself, so that the internal / external pressure difference appears as an up-down position of the distal end portion 70a. Thus, the internal / external pressure relationship can be detected with high accuracy, and a more accurate leak determination can be performed.

  Instead of the bellows-like high expansion / contraction part 70, as shown in FIG. 14B, a part of the material of the outer shell 10c may be easily deformable member (resin member) 80. The easily deformable member 80 is deformed more greatly than the main body itself of the outer shell 10c according to the inner / outer pressure difference of the outer shell 10c, and the inner / outer pressure difference is enlarged. Accordingly, the internal and external pressure relations can be detected with high accuracy by the displacement sensor 82 as shown in the figure, and a more accurate leak determination can be performed. It should be noted that a strain gauge may be directly attached to the easily deformable member 80 to detect the strain caused by the deformation. In this case as well, the strain appears to be amplified more than the main body of the outer shell 10c itself. It can be detected with high accuracy, and more accurate leak determination is possible.

  Further, the position where the sensor for measuring the fuel level SGL such as the fuel sender gauge 14 is arranged may be positively increased in rigidity. That is, a configuration or material that is difficult to be deformed depending on the internal / external pressure difference may be used. This enables more accurate leak diagnosis.

  DESCRIPTION OF SYMBOLS 2 ... Internal combustion engine, 4 ... Fuel supply system, 6 ... Intake port, 8 ... Fuel injection valve, 10 ... Fuel tank, 10a ... Upper space, 10b, 10c ... Outer shell, 10d ... Fuel, 12 ... Fuel pump module, 14 ... Fuel sender gauge, 14a ... float, 16 ... fuel inlet pipe, 16a ... cap, 16b ... fuel filler port, 16c ... circulation pipe, 16d ... fuel inlet box, 16e ... fuel lid, 18 ... canister, 20 ... discharge passage, 22 ... blockade Valve unit, 22a ... Sealing valve, 22b ... Relief valve, 24 ... ORVR valve, 26 ... Rollover valve, 28 ... Air introduction passage, 28a ... Air filter, 30 ... CCV, 32 ... Purge passage, 34 ... Throttle valve, 36 ... Intake passage, 38 ... Purge control valve, 40 ... Sir Tank, 42 ... Canister internal pressure sensor, 44 ... Air filter, 46 ... Air flow meter, 48 ... Accelerator opening sensor, 50 ... Engine speed sensor, 52 ... Ignition switch (IGSW), 54 ... ECU, 56 ... Dashboard warning Lamp: 60 ... Displacement sensor, 60a ... Contact, 62 ... Underfloor panel, 64 ... Displacement sensor, 66 ... Strain gauge, 70 ... Highly stretchable part, 70a ... Tip part, 72 ... Displacement sensor, 80 ... Easily deformable member, 82: Displacement sensor.

Claims (31)

Leakage detection of a fuel supply system characterized in that a section set in a fuel supply system of an internal combustion engine is sealed in an airtight state, and a leakage state of the section is detected based on deformation of an outer shell constituting the sealed section Method. 2. The fuel supply system leak detection method according to claim 1, wherein a deformation of the outer shell is detected after a predetermined time has elapsed after the compartment is sealed in an airtight state, and the leak state of the compartment is detected based on the detection result. A fuel supply system leak detection method comprising: 3. The fuel supply system leak detection method according to claim 1 or 2, wherein the blockage for bringing the compartment into an airtight state is performed by closing a valve provided in a path directly or indirectly connected to the outside from the compartment. A fuel supply system leak detection method. A fuel supply system leak characterized in that a compartment set in a fuel supply system of an internal combustion engine is in a pressurized or depressurized state, and a leak state of the compartment is detected based on deformation of an outer shell constituting the compartment in the pressure state Detection method. 5. The fuel supply system leak detection method according to claim 4, wherein the decompression state of the compartment is performed by introducing an intake negative pressure of an internal combustion engine into the compartment. 6. The fuel supply system leak detection method according to claim 1, wherein the deformation of the outer shell is determined to have no leak when the outer shell is deformed when the deformation amount is larger than a predetermined deformation amount. 7. A fuel supply system leak detection method. The fuel supply system leak detection method according to any one of claims 1 to 6, wherein the section is a section including a fuel tank. 7. The fuel supply system leak detection method according to claim 1, wherein the section is a section including a fuel tank and a canister. 9. The fuel supply system leak detection method according to claim 7 or 8, wherein a deformation amount is detected in a portion that is easily deformed in accordance with a pressure difference between the inside and the outside of the fuel tank within the outside of the fuel tank. A fuel supply system leak detection method, comprising: detecting a leak state of the section based on a quantity. The fuel supply system leak detection method according to any one of claims 7 to 9, wherein at least a lower outline of the fuel tank is a portion that is easily deformed according to a pressure difference between the inside and outside of the fuel tank. A fuel supply system leak detection method, comprising: detecting a deformation amount of a lower shell based on a change amount of a liquid level of a fuel stored in the fuel tank. 10. The fuel supply system leak detection method according to claim 7, wherein a change in an interval between a portion that is easily deformed according to a pressure difference between the inside and outside of the fuel tank and a configuration other than the fuel tank. A fuel supply system leak detection method, comprising: detecting a deformation amount of the outer shell based on an amount. The fuel supply system leak detection method according to any one of claims 7 to 9, wherein the deformation amount of the outer shell is based on a strain change amount in a portion that is easily deformed according to a pressure difference between the inside and the outside of the fuel tank. The fuel supply system leak detection method characterized by detecting. The fuel supply system leak detection method according to any one of claims 1 to 4 and 6 to 12, wherein the detection of the leak state is performed while the internal combustion engine is stopped. Method. 15. The fuel supply system leak detection method according to claim 13, wherein the detection timing of the leak state during the stop of the internal combustion engine according to the length of the operation period of the internal combustion engine immediately before the stop of the internal combustion engine or the magnitude of the integrated rotational speed. The fuel supply system leak detection method characterized by adjusting the fuel consumption. 14. The fuel supply system leak detection method according to claim 13, wherein the internal combustion engine is for driving a vehicle, and the internal combustion engine is stopped according to a length of a vehicle travel period or a travel distance immediately before the stop of the internal combustion engine. A fuel supply system leak detection method comprising adjusting a detection timing of a leak state in the fuel supply system. A leak diagnosis apparatus for a fuel supply system of an internal combustion engine,
Sealing means for sealing a section set in the fuel supply system of the internal combustion engine in an airtight state;
Deformation amount detecting means for detecting the deformation amount of the outer shell constituting the section;
Leak determination means for determining the presence or absence of leakage in the compartment based on the deformation amount of the outer shell detected by the deformation amount detection means after the compartment is sealed in an airtight state by the sealing means;
A fuel supply system leak diagnosis apparatus comprising: 17. The fuel supply system leak diagnostic device according to claim 16, wherein the leak determination means is detected by the deformation amount detection means after a predetermined time has elapsed after the blockade means has sealed the compartment in an airtight state. A fuel supply system leak diagnostic apparatus, wherein the presence or absence of a leak in the section is determined based on a deformation amount of the outer shell. 18. The fuel supply system leak diagnosis apparatus according to claim 16, wherein the sealing means is a valve provided in a path directly or indirectly connected to the outside from the section. Leak diagnostic device. A leak diagnosis apparatus for a fuel supply system of an internal combustion engine,
A pressure introduction path for introducing positive pressure or negative pressure into a section set in the fuel supply system of the internal combustion engine;
Sealing means for sealing the compartment in an airtight state except for the pressure introduction path;
Deformation amount detecting means for detecting the deformation amount of the outer shell constituting the section;
Based on the deformation amount of the outer shell detected by the deformation amount detection means after performing the introduction of positive pressure or negative pressure to the compartment from the pressure introduction path and the blockage of the compartment by the sealing means. Leak determination means for determining whether there is a leak in the section;
A fuel supply system leak diagnosis apparatus comprising: 20. The fuel supply system leak diagnosis apparatus according to claim 19, wherein the introduction of the negative pressure from the pressure introduction path to the section is introduction of an intake negative pressure of the internal combustion engine. apparatus. 21. The fuel supply system leak diagnosis apparatus according to claim 16, wherein the leak determination unit determines that there is no leak when a deformation amount of the outer shell is larger than a predetermined deformation amount. Fuel supply system leak diagnosis device. The fuel supply system leak diagnosis apparatus according to any one of claims 16 to 21, wherein the section is a section including a fuel tank. The fuel supply system leak diagnosis apparatus according to any one of claims 16 to 21, wherein the section includes a fuel tank and a canister. 24. The fuel supply system leak diagnosis apparatus according to claim 22, wherein the deformation amount detection means is a deformation amount in a portion that is easily deformed in accordance with a pressure difference between the inside and outside of the fuel tank within the outer surface of the fuel tank. A fuel supply system leak diagnosis device characterized by 25. The fuel supply system leak diagnosis device according to claim 22, wherein at least a lower outer shell of the fuel tank is a portion that is easily deformed according to a pressure difference between the inside and the outside of the fuel tank. The deformation amount detecting means detects the deformation amount of the lower outer shell based on the amount of change in the liquid level of the fuel stored in the fuel tank. . 26. The fuel supply system leak diagnosis apparatus according to claim 25, wherein the fuel tank includes a portion that is easily deformed according to an internal and external pressure difference and a portion that is not easily deformed, and a center position of the easily deformable portion is the deformation. The fuel supply system leak diagnosis characterized in that the deformation amount detecting means for measuring the liquid level of the fuel in the fuel tank is arranged in the hardly deformable part. apparatus. 25. The fuel supply system leak diagnosis device according to claim 22, wherein the deformation amount detecting means is a portion that easily deforms the deformation amount of the outer shell according to a pressure difference between the inside and outside of the fuel tank. And a fuel supply system leak diagnosis apparatus, wherein the change amount is detected as a change amount of an interval between the fuel tank and a configuration other than the fuel tank. 25. The fuel supply system leak diagnostic apparatus according to claim 22, wherein the deformation amount detecting means is a portion that is easily deformed according to a pressure difference between the inside and outside of the fuel tank as the amount of deformation of the outer shell. A fuel supply system leak diagnostic apparatus characterized by detecting a change in distortion in the fuel. 30. The fuel supply system leak diagnosis apparatus according to claim 16, wherein the leak determination means executes the determination of the presence or absence of the leak while the internal combustion engine is stopped. A fuel supply system leak diagnosis device. 30. The fuel supply system leak diagnosis apparatus according to claim 29, wherein the leak determination means measures the length of the operation period of the internal combustion engine or the magnitude of the integrated rotational speed immediately before the stop of the internal combustion engine, and according to the measurement result. Then, the fuel supply system leak diagnosis apparatus characterized by adjusting the determination timing of the presence or absence of the leak while the internal combustion engine is stopped. 30. The fuel supply system leak diagnostic apparatus according to claim 29, wherein the internal combustion engine is for driving a vehicle, and the leak determination means measures a length of a vehicle travel period or a travel distance immediately before the stop of the internal combustion engine. A fuel supply system leak diagnosis apparatus that adjusts the determination timing of the presence or absence of the leak while the internal combustion engine is stopped according to the measurement result.

Images