JP2010071198A - Device and method for diagnosing failure of in-tank canister system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a failure diagnosis for an in-tank canister system having a simple structure, short measurement time, and high reliability; and a method thereof. <P>SOLUTION: The failure diagnosis device for the in-tank canister system includes an atmospheric air shut-off means 16 capable of shutting off an atmospheric air introduction passage 20, a positive pressure generating means 14 applying positive pressure and negative pressure in a canister 10, an evaporated fuel introduction passage opening/closing means 23 opening and closing an evaporated fuel introduction passage according to positive pressure and negative pressure in the canister 10, and a pressure detection means 15 detecting pressure in the canister. The failure diagnosis device for the in-tank canister system is provided with a failure diagnosis means of a canister and the fuel tank diagnosing occurrence of a failure in the canister 10 and the fuel tank 1 when the evaporated fuel introduction passage is opened by pressure measured by a pressure detection means, and it is determined if a failure occurs on the canister when the evaporated fuel introduction passage is closed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an in-tank canister system in which a canister is formed in a fuel tank for an automobile or the like, each of the fuel tank and the canister being perforated or cracked, leakage of evaporated fuel, etc. (hereinafter referred to as failure). The present invention relates to a failure diagnosis apparatus and failure diagnosis method for an in-tank canister system.

  Conventionally, a canister is attached to the fuel system in order to prevent the evaporated fuel generated in the fuel tank from being released into the atmosphere (see, for example, Patent Document 1). The canister temporarily holds the evaporated fuel generated in the fuel tank in the canister, and introduces (purges) the evaporated fuel into the intake system using the negative pressure of the intake system of the engine.

  When a failure occurs in the fuel tank or canister, the evaporated fuel leaks from the failure location into the atmosphere, so it is important to detect the failure of the fuel tank or canister at an early stage. Therefore, as a failure diagnosis method, first, the fuel tank and the canister are shut off from the atmosphere, and the negative pressure in the intake system of the engine is used to make the inside of the fuel tank and the canister negative. When the inside reaches a predetermined negative pressure, the suction of the fuel tank and the canister is stopped, and the fuel tank and the canister are sealed. Then, the change in pressure inside the fuel tank and the canister is measured.

  If there is no failure in the fuel tank and canister, the pressure inside the fuel tank and canister changes little or increases little by little, but if there is a failure in the fuel tank and canister, the pressure inside the fuel tank and canister The pressure quickly becomes atmospheric pressure. For this reason, failure diagnosis can be performed based on changes in pressure inside the fuel tank and the canister.

  On the other hand, in order to reduce the weight and cost of the vehicle by reducing the piping and joint parts connecting the fuel tank and the canister, and to prevent the evaporative fuel from leaking out of the piping and the joint part, the canister is installed in the fuel tank. (See, for example, Patent Documents 2 and 3).

  In this case, even if the failure diagnosis is performed with the negative pressure inside the fuel tank, the canister exists inside the fuel tank, so that the pressure change inside the fuel tank occurs regardless of whether or not the canister has failed. Even if the tank failure can be diagnosed, the canister failure diagnosis cannot be performed.

  Therefore, in Patent Document 2, a three-way switching valve is used to communicate the canister with the atmospheric pressure, and after the canister and the fuel tank are shut off, only the inside of the fuel tank is set to a negative pressure and the change in pressure is measured. If the pressure immediately becomes atmospheric pressure after the negative pressure, the fuel tank or canister is diagnosed as having a failure.

  Next, the canister is shut off from the atmosphere and communicated between the canister and the fuel tank, and then the fuel tank and the canister are brought to a negative pressure. After the purge passage is shut off, if the pressure inside the fuel tank immediately becomes atmospheric pressure, it is diagnosed that the fuel tank is faulty. If there is little change in the pressure inside the fuel tank, the canister is faulty. Diagnose it.

In the case of Patent Document 3, as shown in FIG. 11, the switching valve 116 provided in the evaporation pipe 112 is opened, the inside of the canister 111 in the fuel tank 103 and the inside of the fuel tank 103 are communicated, and the air introduction pipe The negative pressure pump 117 provided at 113 is driven to reduce the pressure in the fuel tank 103, and the presence or absence of a failure in the fuel tank 103 is diagnosed by detecting the amount of pressure drop. Thereafter, the switching valve 116 is closed, the communication between the fuel tank 103 and the canister 111 is closed, the negative pressure pump 117 is driven to lower the pressure in the canister 111, and a change in pressure is detected to detect the canister 111. This is to diagnose the presence or absence of failure.
JP 2005-299560 A JP 2001-115915 A JP 2006-037783 A

In the case of Patent Document 2, a three-way switching lunch box is necessary, and the structure becomes complicated. In addition, when the fuel tank has failed, there is a problem that it cannot be diagnosed whether the canister has failed.
In the case of Patent Document 3, the switching valve 116 and the shutoff valve for the air introduction pipe 113 are required in the fuel tank 103. When a failure of the canister 111 is detected, the inside of the canister 111 is set to a negative pressure, It took a very long time to measure the pressure change in order to detect the leak charge.
Therefore, it is an object of the present invention to provide a failure diagnosis apparatus and method for a tank canister system that has a simple structure, a short measurement time, and high reliability.

The present invention according to claim 1 for solving the above problems includes a canister disposed in the fuel tank, an evaporative fuel introduction passage for introducing evaporative fuel generated in the fuel tank into the canister, and an atmosphere in the canister. In an in-tank canister system failure diagnosis device comprising an air introduction passage for introducing gas and a purge passage for introducing evaporated fuel in the canister into an intake system of an internal combustion engine,
An air blocking means capable of blocking the air introduction passage;
A positive / negative pressure generating means capable of applying a positive pressure and a negative pressure in the canister; an evaporative fuel introduction passage opening / closing means for opening / closing the evaporative fuel introduction path according to the positive pressure and the negative pressure in the canister;
Pressure detecting means for detecting the pressure in the canister,
Diagnose whether the canister and the fuel tank have failed by the pressure measured by the pressure detection means when the evaporative fuel introduction passage is open, or if the canister has a failure when the evaporative fuel introduction passage is closed A failure diagnosis device for an in-tank canister system comprising a canister for diagnosis and a failure diagnosis means for a fuel tank.

  In the first aspect of the present invention, the canister is sealed by blocking the atmosphere introduction passage by the atmosphere blocking means capable of blocking the atmosphere introduction passage for introducing the atmosphere to the canister, and the positive or negative pressure is generated in the canister by the positive / negative pressure generating means. Negative pressure can be applied. The evaporative fuel introduction passage opening and closing means for opening and closing the evaporative fuel introduction passage according to the positive pressure or the negative pressure in the canister opens and closes the evaporative fuel introduction passage for introducing the evaporative fuel generated in the fuel tank into the canister. can do.

Therefore, when the evaporative fuel introduction passage is open, the positive / negative pressure generating means applies a positive or negative pressure to both the canister and the fuel tank in the same manner, and the pressure measured by the pressure detecting means attached to the canister By measuring the above, it is possible to diagnose whether or not a failure has occurred in the canister and the fuel tank by the canister and fuel tank failure diagnosis means.
In this case, if the inside of the canister is made negative or positive with the positive / negative pressure generating means, the evaporative fuel introduction passage is closed, so that the negative or positive pressure is applied only to the canister and attached to the canister. By measuring the pressure measured by the detected pressure detecting means, it is possible to diagnose whether the canister has a failure by the failure diagnosing means.
Thus, the evaporative fuel introduction passage opening / closing means can be operated by setting the canister to positive pressure or negative pressure by the positive / negative pressure generating means, and the evaporative fuel introduction passage can be opened / closed. Tank and canister failures can be easily diagnosed.

According to the present invention of claim 2, when the evaporative fuel introduction passage opening / closing means has two chambers, one chamber communicates with the evaporative fuel introduction passage, the other chamber communicates with the canister, and the inside of the canister has a negative pressure. When the evaporative fuel introduction passage is opened and the inside of the canister is at a positive pressure, the evaporative fuel introduction passage is closed,
The pressure detection means measures the pressure in the canister and the fuel tank when the evaporative fuel introduction passage is open, and measures the pressure in the canister when the evaporative fuel introduction passage is closed. It is a failure diagnosis device of an in-tank canister system that transmits to a diagnosis means.

In the present invention of claim 2, when the evaporative fuel introduction passage opening / closing means has two chambers, one chamber communicates with the evaporative fuel introduction passage, the other chamber communicates with the canister, and the inside of the canister has a negative pressure. When the evaporative fuel introduction passage is opened and the inside of the canister is at a positive pressure, the evaporative fuel introduction passage is closed. For this reason, the vaporized fuel introduction passage can be opened and the negative pressure can be similarly applied to both the canister and the fuel tank only by setting the inside of the canister to a negative pressure with a positive / negative pressure pump.
By measuring the pressure measured by the pressure detecting means attached to the canister and sending the pressure value to the failure diagnosing means, it is possible to diagnose whether a failure has occurred in the canister and the fuel tank.

  Next, when the inside of the canister is brought to a positive pressure by the positive / negative pressure generating means, the vaporized fuel introduction passage is closed, and only the inside of the canister can be made a positive pressure. Then, by measuring the pressure measured by the pressure detecting means attached to the canister and sending the pressure value to the failure diagnosing means, it is possible to diagnose whether or not the canister has failed.

According to the third aspect of the present invention, when the evaporative fuel introduction passage opening / closing means has two chambers, one chamber communicates with the evaporative fuel introduction passage, the other chamber communicates with the atmosphere, and the canister has a positive pressure. When the evaporative fuel introduction passage is opened and the inside of the canister is under negative pressure, the evaporative fuel introduction passage is closed.
The pressure detection means measures the pressure in the canister and the fuel tank when the evaporative fuel introduction passage is open, and measures the pressure in the canister when the evaporative fuel introduction passage is closed. It is a failure diagnosis device of an in-tank canister system that transmits to a diagnosis means.

According to the third aspect of the present invention, the evaporative fuel introduction passage opening / closing means has two chambers, one chamber communicates with the evaporative fuel introduction passage, the other chamber communicates with the atmosphere, and the inside of the canister is at a positive pressure. The evaporative fuel introduction passage is opened, and the evaporative fuel introduction passage is closed when the inside of the canister has a negative pressure. For this reason, the vaporized fuel introduction passage can be opened and the positive pressure can be similarly applied to both the canister and the fuel tank only by setting the inside of the canister to a positive pressure with the positive and negative pressure pumps.
By measuring the pressure measured by the pressure detection means attached to the canister, it is possible to diagnose whether or not a failure has occurred in the canister and the fuel tank by sending the pressure value to the failure diagnosis means.

  Next, when the inside of the canister is made negative pressure by the positive / negative pressure generating means, the vaporized fuel introduction passage is closed, and only the inside of the canister can be made negative pressure. Then, by measuring the pressure measured by the pressure detecting means attached to the canister and sending the pressure value to the failure diagnosing means, it is possible to diagnose whether or not the canister has failed.

  According to a fourth aspect of the present invention, there is provided a failure diagnosis apparatus for an in-tank canister system, wherein the evaporative fuel introduction passage opening / closing means opens and closes the evaporative fuel introduction passage by a diaphragm.

  In the present invention of claim 4, the evaporative fuel introduction passage opening / closing means opens and closes the evaporative fuel introduction passage by the diaphragm, so that the evaporative fuel introduction passage can be opened and closed only by switching the positive / negative pressure of the canister by the positive / negative pressure pump. In addition, a complicated mechanism such as a solenoid valve is not required, and it is simple, light, and cost can be reduced.

  The present invention of claim 5 is a failure diagnosis apparatus for an in-tank canister system in which the pressure detecting means has reference means before detecting the pressure in the canister.

  In the present invention of claim 5, since the pressure detection means has the reference means before detecting the pressure in the canister, the failure diagnosis device can refer to the reference data and make an accurate diagnosis.

  According to the sixth aspect of the present invention, the reference means includes a pressure detection means and a positive / negative pressure generator connected by a pressure detection pipe, and one end of the pressure detection pipe is closed by the atmospheric shut-off means so that the pressure detection pipe is positively or negatively pressurized. Thus, the in-tank canister system failure diagnosis device is configured to measure the pressure by taking in and out the air in the pressure detection tube from the orifice formed in the pressure detection tube.

  In the present invention of claim 6, the pressure detecting means and the positive / negative pressure generating device are connected by the pressure detecting pipe, the one end of the pressure detecting pipe is closed by the atmospheric shut-off means, and the pressure detecting pipe is made positive pressure or negative pressure. Because the pressure is measured by taking in and out the air in the pressure detection tube from the orifice formed in the pressure detection tube, the reference data can be easily obtained with a simple device, and the diameter of the orifice can be changed. Thus, the diagnostic criteria can be set easily.

The present invention of claim 7 includes a canister disposed in the fuel tank, an evaporative fuel introduction passage for introducing evaporative fuel generated in the fuel tank into the canister, an air introduction passage for introducing air into the canister, In the in-tank canister system failure diagnosis method having a purge passage for introducing the evaporated fuel in the canister into the intake system of the internal combustion engine,
Block the air introduction passage with air blocking means,
A positive or negative pressure is applied to the canister by a positive / negative pressure generator,
The evaporative fuel introduction passage opening and closing means opens and closes the evaporative fuel introduction passage according to the positive pressure and negative pressure in the canister,
When the evaporative fuel introduction passage is open, both the pressure in the canister and the fuel tank are detected by the pressure detection means, and the failure diagnosis means diagnoses whether the canister and the fuel tank have failed due to the pressure. This is a failure diagnosis method for an in-tank canister system in which the pressure inside the canister is detected by pressure detection means when the introduction passage is closed, and the failure diagnosis means diagnoses whether the canister has failed due to the pressure.

  According to the seventh aspect of the present invention, the canister is sealed by blocking the air introduction passage by the air blocking means capable of blocking the air introduction passage for introducing air into the canister, and the positive or negative pressure is generated in the canister by the positive / negative pressure generating means. Negative pressure can be applied. And by making positive pressure or negative pressure in the canister, the evaporative fuel introduction passage can be opened and closed by the evaporative fuel introduction passage opening / closing means, and the operation is simple.

When the evaporative fuel introduction passage is open, positive or negative pressure is applied to both the canister and the fuel tank by the positive / negative pressure generating means, and the pressure measured by the pressure detecting means attached to the canister is measured. Thus, it is possible to diagnose whether a failure has occurred in the canister and the fuel tank by the failure diagnosis means.
In this case, if the inside of the canister is made negative or positive with the positive / negative pressure generating means, the evaporative fuel introduction passage is closed, so that the negative or positive pressure is applied only to the canister and attached to the canister. It is possible to diagnose whether or not the canister has a failure by measuring the pressure measured by the pressure detection means and sending the pressure value to the failure diagnosis means.
In this way, the evaporative fuel introduction passage can be opened and closed by setting the canister to a positive or negative pressure by the positive / negative pressure generating means, and the failure of the fuel tank and the canister can be easily diagnosed.

In the present invention of claim 8, the inside of the canister is made negative by the positive / negative pressure generator,
The evaporative fuel introduction passage opening / closing means configured to have two chambers, one chamber communicating with the evaporative fuel introduction passage, and the other chamber communicating with the canister, allows the evaporative fuel introduction passage to be opened by the negative pressure in the canister. Open,
After making the inside of the canister and the fuel tank negative with the positive / negative pressure generator, the pressure detection means measures the pressure in the canister and the fuel tank at the same time, sends the pressure to the failure detection means, and the canister and the fuel tank fail. Diagnose if it occurs,
A positive / negative pressure generator creates positive pressure inside the canister,
The evaporative fuel introduction passage opening / closing means closes the evaporative fuel introduction passage by the positive pressure in the canister,
This is a failure diagnosis method for an in-tank canister system provided with failure detection means for diagnosing whether a failure has occurred in the canister by sending the pressure of the canister measured by the pressure detection means to the failure detection means.

In the present invention of claim 8, when the evaporative fuel introduction passage opening / closing means has two chambers, one chamber communicates with the evaporative fuel introduction passage, the other chamber communicates with the canister, and the inside of the canister has a negative pressure. When the evaporative fuel introduction passage is opened and the inside of the canister is at a positive pressure, the evaporative fuel introduction passage is closed. For this reason, the vaporized fuel introduction passage can be opened and the negative pressure can be similarly applied to both the canister and the fuel tank only by setting the inside of the canister to a negative pressure with a positive / negative pressure pump.
By measuring the pressure measured by the pressure detection means attached to the canister and sending the pressure value to the failure diagnosis means, it is possible to diagnose whether a failure has occurred in the canister and the fuel tank.

  Next, when the inside of the canister is brought to a positive pressure by the positive / negative pressure generating means, the vaporized fuel introduction passage is closed, and only the inside of the canister can be made a positive pressure. Then, by measuring the pressure measured by the pressure detection means attached to the canister and sending the pressure value to the failure diagnosis means, it is possible to diagnose whether or not the canister has a failure.

In the present invention of claim 9, the inside of the canister is made positive by the positive / negative pressure generator,
The evaporative fuel introduction passage opening / closing means configured to have two chambers, one chamber communicating with the evaporative fuel introduction passage, and the other chamber communicating with the canister, has the evaporative fuel introduction passage opened by the positive pressure in the canister. Open,
After the positive and negative pressure generators make the canister and the fuel tank positive, the pressure detection means simultaneously measures the pressure in the canister and the fuel tank, sends the pressure to the failure detection means, and the canister and the fuel tank Diagnose if it occurs,
The inside of the canister is made negative by a positive / negative pressure generator,
The evaporative fuel introduction passage opening / closing means closes the evaporative fuel introduction passage by the negative pressure in the canister,
This is a failure diagnosis method for an in-tank canister system provided with failure detection means for diagnosing whether a failure has occurred in the canister by sending the pressure of the canister measured by the pressure detection means to the failure detection means.

In the present invention of claim 9, the evaporative fuel introduction passage opening / closing means has two chambers, one chamber communicates with the evaporative fuel introduction passage, the other chamber communicates with the atmosphere, and when the inside of the canister is at a positive pressure When the evaporative fuel introduction passage is opened and the inside of the canister has a negative pressure, the evaporative fuel introduction passage is closed. For this reason, the vaporized fuel introduction passage can be opened and the positive pressure can be similarly applied to both the canister and the fuel tank only by setting the inside of the canister to a positive pressure with the positive and negative pressure pumps.
By measuring the pressure measured by the pressure detection means attached to the canister and sending the pressure value to the failure diagnosis means, it is possible to diagnose whether a failure has occurred in the canister and the fuel tank.

  Next, when the inside of the canister is made negative pressure by the positive / negative pressure generating means, the vaporized fuel introduction passage is closed, and only the inside of the canister can be made negative pressure. Then, by measuring the pressure measured by the pressure detection means attached to the canister and sending the pressure value to the failure diagnosis means, it is possible to diagnose whether or not the canister has a failure.

  The present invention according to claim 10 is a failure diagnosis method for an in-tank canister system in which the evaporative fuel introduction passage opening / closing means opens and closes the evaporative fuel introduction passage by operating a diaphragm by a positive pressure or a negative pressure of the canister.

  In the present invention of claim 10, the evaporative fuel introduction passage opening / closing means opens and closes the evaporative fuel introduction passage by the diaphragm, so that the evaporative fuel introduction passage can be opened and closed only by switching the positive / negative pressure by the positive / negative pressure pump, A complicated mechanism such as a solenoid valve is not required, and it is simple and light, and the cost can be reduced.

  The present invention of claim 11 is a failure diagnosis method for an in-tank canister system in which a change in pressure is detected by a reference means before the pressure in the canister is detected, and the failure detection means detects a failure based on the result of the pressure in the reference means. It is.

  In the present invention of claim 11, since the pressure detection means has the reference means before detecting the pressure in the canister, the failure diagnosis apparatus can refer to the reference data and can make an accurate diagnosis.

  According to the twelfth aspect of the present invention, the reference means includes a pressure detection means and a positive / negative pressure generator connected by a pressure detection pipe, and one end of the pressure detection pipe is closed by the atmospheric shut-off means so that the pressure detection pipe is positively or negatively pressured. Thus, there is provided a fault diagnosis method for an in-tank canister system formed to measure pressure by taking air in and out of the pressure detection tube through an orifice formed in the pressure detection tube.

  In the present invention of claim 12, the reference means includes a pressure detection means and a positive / negative pressure generator connected by a pressure detection pipe, the one end of the pressure detection pipe is closed by the atmospheric shut-off means, and the inside of the pressure detection pipe is made positive pressure or negative pressure. Because the pressure is measured by taking in and out the air in the pressure detection tube from the orifice formed in the pressure detection tube, the reference data can be easily obtained with a simple device, and the diameter of the orifice can be changed. Thus, the diagnostic criteria can be set easily.

Diagnose whether a failure has occurred in the canister and the fuel tank by applying positive or negative pressure to both the canister and the fuel tank in the same way with the positive and negative pressure generating means and measuring the pressure measured by the pressure detecting means. Can do.
Furthermore, since the evaporated fuel introduction passage is closed when the pressure is negative or positive, the canister malfunctions by applying a negative or positive pressure only to the inside of the canister and measuring the pressure measured by the pressure detection means. It can be diagnosed if it occurs.
In this way, the evaporative fuel introduction passage can be opened and closed by setting the canister to a positive or negative pressure by the positive / negative pressure generating means, and the failure of the fuel tank and the canister can be easily diagnosed.

  An in-tank canister system failure diagnosis apparatus and method according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the fuel tank 1 according to the first embodiment of the present invention, and FIG. 2 is a graph showing changes in pressure in the fuel tank 1 and the canister 10 for failure diagnosis.

  FIG. 3 is a partially enlarged cross-sectional view of the upper portion of the canister 10, and FIG. 4 is a partially enlarged cross-sectional view of a portion of the evaporated fuel introduction passage that connects the fuel tank 1 and the canister 10. FIG. 5 is a flowchart showing a determination procedure for failure diagnosis, and FIG. 6 is a view showing operating states of the solenoid valve, the positive / negative pressure pump, and the pressure sensor during running, refueling, and failure diagnosis.

  FIG. 7 is a cross-sectional view of the fuel tank 1 according to the second embodiment of the present invention, and FIG. 8 is a graph showing changes in pressure in the fuel tank 1 and the canister 10 for failure diagnosis. FIG. 9 is a flowchart showing a determination procedure for failure diagnosis, and FIG. 6 is a diagram showing operating states of the solenoid valve, the positive / negative pressure pump, and the pressure sensor during traveling, refueling, and failure diagnosis.

In the first embodiment of the present invention, as shown in FIG. 1, the fuel tank 1 is an in-tank canister system in which a canister 10 is integrally formed.
The fuel tank 1 is provided with a fuel pump 2 on the inner bottom surface, and the fuel in the fuel tank 1 is sent to the injector 32 via the fuel delivery pipe 3 and blown into the intake manifold 33 to drive the engine.

A reinforcing column 4 can be attached inside the fuel tank 1 in order to increase the strength in the vertical direction. An inspection hole for inspecting the fuel pump 2 and the like is formed in the upper wall of the fuel tank 1 and is closed by a cap 5.
Further, a fuel supply pipe 7 and a breather pipe 8 for injecting fuel from the fuel supply port 6 to the fuel tank 1 are attached.

The canister 10 is integrally formed inside the upper wall of the fuel tank 1. The upper and lower portions of the fuel tank 1 are separately formed of synthetic resin by injection molding, and after the fuel pump 2 and the canister 10 are incorporated therein, the upper and lower portions are integrally joined.
As the upper wall constituting the canister outer wall 11 of the canister 10, the upper wall of the fuel tank 1 is commonly used, and the side wall constituting the canister outer wall 11 is integrally extended from the upper wall. The bottom wall constituting the canister outer wall 11 is separately attached to the side wall by adhesion or welding so as to be airtight.

  Inside the canister 10, two canister inner walls 12 and 13 are formed at intervals so as to divide the inner chamber of the canister 10. The canister 10 is filled with activated carbon or the like that adsorbs evaporated fuel. A gap is formed between the bottom ends of the two canister inner walls 12 and 13 so that the evaporated fuel can flow between the bottom walls of the canister 10.

As shown in FIG. 3, an air introduction portion 20 is provided on the outer surface of the outer wall of the fuel tank 1 that is divided by the canister inner wall 12. A filter 21 is attached to the inlet of the atmosphere introduction unit 20 and can remove dust in the atmosphere.
A positive / negative pressure pump 14, a pressure sensor 15, and a solenoid valve 16 are attached to the outer surface of the canister 10 (also used as the outer wall of the fuel tank 1) inside the air introduction unit 20.

  The positive / negative pressure pump 14 and the pressure sensor 15 pass through the outer wall of the canister 10 and are connected to a pressure detection pipe 17 provided inside the canister 10. A pressure detection tube opening 17 a that opens upward is formed at the tip of the pressure detection tube 17, and an orifice 18 is formed at the bottom of the tip of the pressure detection tube 17. The orifice 18 is a through hole corresponding to a diameter of 0.5 mm in the present embodiment.

  The electromagnetic valve 16 is attached to the opening 11a formed in the canister outer wall 11 with a gap. The solenoid valve 16 has a drive shaft extending inside the canister 10, and a large-diameter seal 19 a and a small-diameter seal 19 b are attached to the drive shaft. The large-diameter seal 19a can be driven upward by the electromagnetic valve 16 to close the opening 11a, and the small-diameter seal 19b can be driven downward to close the pressure detection tube opening 17a.

  As shown in FIG. 1, the positive / negative pressure pump 14, the pressure sensor 15, and the electromagnetic valve 16 are connected to a controller 40, which is an example of failure diagnosis means, by electric wires, and the positive / negative pressure pump 14 and the electromagnetic valve 16 are driven by the controller 40. The pressure value of the pressure sensor 15 is sent to the controller 40. The positive / negative pressure pump 14 is an example of positive / negative pressure generating means, the pressure sensor 15 is an example of pressure detecting means, and the solenoid valve 16 is an example of an air blocking means.

As shown in FIGS. 1 and 3, a diaphragm communication pipe 22 is attached from the outer surface of the canister outer wall 11 divided by the canister inner wall 12, and is connected to a diaphragm valve mechanism 23 described later.
A purge pipe 34 is attached from the outer surface of the canister outer wall 11 between the canister inner wall 12 and the canister inner wall 13. As shown in FIG. 1, the purge pipe 34 as an example of the purge passage is connected to the intake pipe 30.

As shown in FIG. 4, a diaphragm valve mechanism 23, which is an example of an evaporative fuel introduction passage opening / closing means, is attached to the boundary between the canister 10 and the fuel tank 1. The diaphragm valve mechanism 23 is divided into a diaphragm upper chamber 23e and a diaphragm lower chamber 23f which are two upper and lower chambers by a diaphragm 23a.
The diaphragm communication chamber 22 is connected to the diaphragm upper chamber 23e, and the diaphragm upper chamber 23e and the inside of the canister 10 are communicated with each other. Further, a spring 23b is attached inside the diaphragm upper chamber 23e, and presses the diaphragm 23a downward.

The diaphragm lower chamber 23f is attached with a canister communication pipe 23c, which is a pipe communicating with the canister 10, and its tip is opened and closed by the diaphragm 23a.
A canister outer wall 11 is integrally joined to an outer wall of the diaphragm lower chamber 23 f and is in contact with both the canister 10 and the fuel tank 1. The canister communication pipe 23 c has an outlet provided on the canister 10 side with respect to the canister outer wall 11. The canister outer wall 11 is provided with a check valve 24 through which gas can flow from the canister 10 toward the fuel tank 1 when the canister 10 reaches a predetermined pressure.

A tank communication hole 23d is formed on the fuel tank 1 side of the outer wall of the diaphragm lower chamber 23f.
As shown in FIG. 4, a cutoff valve 25 (or a full tank detection valve) is formed continuously with the tank communication hole 23d. The cut-off valve 25 includes a cut-off valve vent chamber 25d that is continuous with the tank communication hole 23d, and a cut-off valve float chamber 25e that houses the cut-off valve float 25a. A cut-off valve vent hole 25b is formed in the boundary wall between the cut-off valve vent chamber 25d and the cut-off valve float chamber 25e.

  A cut-off valve communication hole 25c is formed in the bottom wall of the cut-off valve float chamber 25e. The cut-off valve float 25a in the cut-off valve float chamber 25e rises and closes the cut-off valve vent 25b when the fuel level in the fuel tank 1 rises, and the fuel enters the canister 10 To prevent.

  The cut-off valve communication hole 25c, the cut-off valve float chamber 25e, the cut-off valve vent hole 25b, the cut-off valve vent chamber 25d, the tank communication hole 23d, the diaphragm lower chamber 23f, and the canister communication pipe 23c constitute an evaporated fuel introduction passage. In this order, the evaporated fuel in the fuel tank 1 passes through the canister 10. And the air which is adsorbed by the activated carbon in the canister 10 and does not contain the evaporated fuel is released to the outside. When the engine is started and air is sucked from the intake pipe 30 through the purge pipe 34, the evaporated fuel adsorbed on the activated carbon in the canister 10 is sent to the engine together with the air from the intake pipe 30.

Next, a diagnosis method for the in-tank canister system will be described.
As shown in FIG. 2, first, negative pressure reference measurement is performed. By the negative pressure reference measurement, the controller 40 can refer to the reference data in a failure diagnosis method described later, and an accurate diagnosis can be made.

In the reference measurement, the solenoid valve 16 is first operated by the controller 40, the pressure detection tube opening 17a of the pressure detection tube 17 is closed by the small diameter seal 19b, and the opening 11a is opened by the large diameter seal 19a to communicate with the atmosphere introduction unit 20. . Then, the controller 40 operates the positive / negative pressure pump 14 to make the pressure detection pipe 17 have a negative pressure. Then, the pressure value of the pressure detection pipe 17 is measured for the negative pressure generated by the difference between the gas flowing in from the orifice 18 and the gas discharged by the positive / negative pressure pump 14 in a state where the positive / negative pressure pump 14 is operated. This pressure value is sent to the controller 40, and the controller 40 looks at this pressure value to check whether the system is operating normally. This is stage A in FIG. This process is “negative pressure reference measurement” shown in the flowchart of FIG.
6 is a reference item portion of the tank body shown in the table of FIG. Here, the solenoid valve is OPEN means that the large-diameter seal 19a is open and the small-diameter seal 19b is closed.

Next, the fuel tank 1 and the canister 10 are inspected.
The electromagnetic valve 16 is operated by the controller 40, the opening 11a of the canister outer wall 11 is closed by the large-diameter seal 19a, and the canister 10 is sealed. The purge pipe 34 is also closed. Then, the controller 40 operates the positive / negative pressure pump 14 to make the inside of the canister 10 have a negative pressure. Then, the negative pressure in the canister 10 is transmitted to the diaphragm upper chamber 23e of the diaphragm valve mechanism 23 by the diaphragm communication pipe 22, the diaphragm 23a rises, the tip of the canister communication pipe 23c opens, and the above-mentioned evaporative fuel introduction passage is opened. It opens, communicates with the fuel tank 1, and the fuel tank 1 also has a negative pressure. This is the initial stage of B shown in FIG. 2, and is the part of the item of the tank body in the table of FIG.

  Next, when the positive / negative pressure pump 14 is continuously operated, the pressure in the fuel tank 1 and the canister 10 continues to decrease as shown in FIG. Then, the pressure is measured by the pressure sensor 15 which is a pressure detecting means attached to the canister 10, and the pressure value is sent to the controller 40. This is the stage after B shown in FIG. At this time, as shown by the solid line in FIG. 2, if there is no failure in the fuel tank 1 and the canister 10, a pressure lower than the pressure value obtained by the reference measurement can be reached. When the pressure drops and becomes constant (C shown in FIG. 2), the controller 40 determines that there is no failure if the pressure is lower than the pressure obtained by the reference measurement.

  On the other hand, when there is a failure in the fuel tank 1 or the canister 10, even if the positive / negative pressure pump 14 continues to be operated, air flows in from the failure point, and the fuel tank 1 and the canister 10, as indicated by the dotted line in FIG. The pressure of the canister 10 does not decrease, and the pressure value of the pressure sensor 15 remains higher than the pressure value obtained by the reference measurement. The pressure value is sent to the controller 40 and compared with the pressure value obtained by the reference measurement to diagnose a failure.

Next, the canister 10 is inspected.
In the inspection of the canister 10, as shown in FIG. 2, first, a positive pressure reference measurement is performed. With the positive pressure reference measurement, reference data can be referred to in a failure diagnosis method described later, and an accurate diagnosis can be made.

  In the reference measurement, similarly to the above, the solenoid valve 16 is operated by the controller 40, and the pressure detection tube opening 17a of the pressure detection tube 17 is closed by the small diameter seal 19b. Then, the controller 40 operates the positive / negative pressure pump 14 to make the pressure detection pipe 17 have a positive pressure. Then, the pressure value of the pressure detection tube 17 is measured for the positive pressure generated by the difference between the gas flowing out from the orifice 18 and the gas blown in by the positive / negative pressure pump 14 in a state where the positive / negative pressure pump 14 is operated. This pressure value is sent to the controller 40 to check whether the system is operating normally. This is stage D in FIG. This process is “positive pressure reference measurement” shown in the flowchart of FIG. 5 and is a reference item of the canister in the table of FIG.

  Next, the solenoid valve 16 is operated by the controller 40, the opening 11a of the canister outer wall 11 is closed by the large diameter seal 19a, and the canister 10 is sealed. The close of the electromagnetic valve 16 in the OBD detection of the canister 10 in FIG. 6 indicates that the opening 11a of the canister outer wall 11 is closed by the large-diameter seal 19a. The purge pipe 34 is also closed. Then, the controller 40 operates the positive / negative pressure pump 14 to make the inside of the canister 10 have a positive pressure.

  Then, the positive pressure in the canister 10 is transmitted to the diaphragm upper chamber 23e of the diaphragm valve mechanism 23 by the diaphragm communication pipe 22, and the diaphragm 23a is lowered to close the tip of the canister communication pipe 23c. As a result, the fuel vapor introduction passage is closed, the communication with the fuel tank 1 is lost, and only the inside of the canister 10 becomes positive pressure. This is the initial stage of E shown in FIG.

  Next, when the positive / negative pressure pump 14 is continuously operated, the pressure in the canister 10 continues to rise as shown in FIG. Then, the pressure is measured by the pressure sensor 15 which is a pressure detecting means attached to the canister 10, and the pressure value is sent to the controller 40. This is the stage after E shown in FIG. At this time, as shown by the solid line in FIG. 2, if the canister 10 has no failure, the controller 40 determines that the pressure is higher than the pressure value obtained by the reference measurement.

On the other hand, if there is a failure in the canister 10, even if the positive / negative pressure pump 14 is continuously operated, air flows out from the failure location, and the pressure of the canister 10 does not increase as indicated by the dotted line shown in FIG. Since the pressure is lower than the pressure value obtained by the reference measurement, the controller 40 determines that the failure has occurred.
Thus, the failure diagnosis of the fuel tank 1 and the canister 10 can be performed with a simple device by sequentially applying the negative pressure and the positive pressure by the positive / negative pressure pump 14.

  Next, a second embodiment will be described based on FIGS. The second embodiment differs from the first embodiment in the mounting position of the diaphragm communication pipe 22 and the way of applying positive pressure and negative pressure to the fuel tank 1 and the canister 10 is different. The description of similar parts is omitted.

The two canister inner walls 12, 13 of the inner chamber of the canister 10 are the same as those in the first embodiment.
As shown in FIG. 7, an air introduction part 20 is provided on the outer surface of the outer wall of the fuel tank 1 that is delimited by the inner wall 12 of the canister. A filter 21 is attached to the inlet of the atmosphere introduction unit 20 and can remove dust in the atmosphere.

A positive / negative pressure pump 14, a pressure sensor 15, and a solenoid valve 16 are attached to the outer surface of the canister 10 (also used as the outer wall of the fuel tank 1) inside the air introduction unit 20.
The positive / negative pressure pump 14 and the pressure sensor 15 are the same as those in the first embodiment in the pressure detection pipe 17 and the orifice 18.

As shown in FIG. 7, a diaphragm communication pipe 22 is attached from the atmosphere introduction unit 20 and is connected to a diaphragm valve mechanism 23 described later.
A diaphragm valve mechanism 23 is attached to the boundary between the canister 10 and the fuel tank 1. The diaphragm valve mechanism 23 is vertically divided into a diaphragm upper chamber 23e and a diaphragm lower chamber 23f by a diaphragm 23a.
The diaphragm upper chamber 23e is connected to the above-described diaphragm communication tube 22, and the diaphragm upper chamber 23e and the air introduction unit 20 communicate with each other, and the pressure thereof is the same as the atmospheric pressure. Further, a spring 23b is attached inside the diaphragm upper chamber 23e, and presses the diaphragm 23a downward.

The diaphragm lower chamber 23f is attached with a canister communication pipe 23c, which is a pipe communicating with the canister 10, and its tip is opened and closed by the diaphragm 23a.
The configuration of the diaphragm lower chamber 23f and the configuration of the cutoff valve 25 are the same as those in the first embodiment.

Next, a diagnosis method for the in-tank canister system will be described.
As shown in FIG. 8, first, a positive pressure reference measurement is performed. With the positive pressure reference measurement, reference data can be referred to in a failure diagnosis method described later, and an accurate diagnosis can be made.

  In the reference measurement, first, the solenoid valve 16 is operated by the controller 40, the pressure detection pipe opening 17a of the pressure detection pipe 17 is closed by the small diameter seal 19b, and the opening 11a of the canister 10 is opened by the large diameter seal 19a. The unit 20 communicates with the unit 20. Then, the controller 40 operates the positive / negative pressure pump 14 to make the pressure detection pipe 17 have a positive pressure. Then, the pressure value of the pressure detection pipe 17 is measured for the positive pressure generated by the difference between the gas flowing out from the orifice 18 and the gas blown in by the positive / negative pressure pump 14 with the positive / negative pressure pump 14 being operated. This pressure value is sent to the controller 40 to check whether the system is operating normally. This is stage A in FIG. This process is the positive pressure reference measurement shown in the flowchart of FIG. 9, and is a reference item of the tank body in the table of FIG.

Next, the fuel tank 1 and the canister 10 are inspected.
The electromagnetic valve 16 is operated by the controller 40, the opening 11a of the canister outer wall 11 is closed by the large-diameter seal 19a, and the canister 10 is sealed. The purge pipe 34 is also closed. Then, the controller 40 operates the positive / negative pressure pump 14 to make the inside of the canister 10 have a positive pressure. Then, the positive pressure in the canister 10 is transmitted to the diaphragm lower chamber 23f of the diaphragm valve mechanism 23 by the canister communication pipe 23c, the diaphragm 23a rises, the tip of the canister communication pipe 23c opens, and the above-mentioned evaporated fuel introduction passage is opened. It opens, communicates with the fuel tank 1, and the fuel tank 1 also has a positive pressure. This is the first stage of B shown in FIG.

  Next, when the positive / negative pressure pump 14 is continuously operated, the pressure in the fuel tank 1 and the canister 10 continues to increase as shown in FIG. Then, a change in pressure is measured by the pressure sensor 15 which is a pressure detecting means attached to the canister 10 and sent to the controller 40. This is the stage after B shown in FIG. At this time, as shown by the solid line in FIG. 8, if there is no failure in the fuel tank 1 and the canister 10, a pressure lower than the pressure value obtained by the reference measurement can be reached. When the pressure rises and becomes constant (C shown in FIG. 8), if the pressure is larger than the pressure obtained by the reference measurement by the controller 40, it is determined that there is no failure.

  On the other hand, when there is a failure in the fuel tank 1 or the canister 10, even if the positive / negative pressure pump 14 is continuously operated, the air flows out from the failure portion, and the fuel tank 1 and the canister 10 as indicated by the dotted line in FIG. Since the pressure of the canister 10 does not decrease and remains at a pressure lower than the pressure value obtained by the reference measurement, the controller 40 determines that a failure has occurred.

Next, the canister 10 is inspected.
In the inspection of the canister 10, first, as shown in FIG. 8, negative pressure reference measurement is performed. By the negative pressure reference measurement, reference data can be referred to in a failure diagnosis method described later, and an accurate diagnosis can be made.

  In the reference measurement, similarly to the above, the electromagnetic valve 16 is operated, and the pressure detection tube opening 17a of the pressure detection tube 17 is closed by the small diameter seal 19b. And the inside of the pressure detection pipe | tube 17 is made into a negative pressure with the positive / negative pressure pump 14. FIG. Then, the pressure value of the pressure detection pipe 17 is measured for the negative pressure generated by the difference between the gas flowing in from the orifice 18 and the gas discharged by the positive / negative pressure pump 14 in a state where the positive / negative pressure pump 14 is operated. This pressure value is sent to the controller 40 to check whether the system is operating normally. This is stage D in FIG. This process is the negative pressure reference measurement shown in the flowchart of FIG. 9, and is a reference item of the canister in the table of FIG.

  Next, the solenoid valve 16 is operated by the controller 40, the opening 11a of the canister outer wall 11 is closed by the large diameter seal 19a, and the canister 10 is sealed. The close of the electromagnetic valve 16 in the OBD detection of the canister 10 in FIG. 10 indicates that the opening 11a of the canister outer wall 11 is closed by the large-diameter seal 19a. The purge pipe 34 is also closed.

  Then, the positive / negative pressure pump 14 is operated to make the inside of the canister 10 have a negative pressure. Then, the negative pressure in the canister 10 is transmitted to the diaphragm lower chamber 23f of the diaphragm valve mechanism 23 by the canister communication pipe 23c, and the diaphragm upper chamber 23e is at atmospheric pressure via the diaphragm communication pipe 22 and the air introduction part 20. 23a descends and the tip of the canister communication pipe 23c is closed. As a result, the fuel vapor introduction passage is closed, communication with the fuel tank 1 is lost, and only the inside of the canister 10 becomes negative pressure. This is the initial stage of E shown in FIG.

  Next, when the positive / negative pressure pump 14 is continuously operated, the pressure in the canister 10 continues to decrease as shown in FIG. Then, the pressure is measured by a pressure sensor 15 which is a pressure detecting means attached to the canister 10. This is the stage after E shown in FIG. At this time, as shown by the solid line in FIG. 8, if there is no failure in the canister 10, a pressure lower than the pressure value obtained by the reference measurement can be reached, and the controller 40 determines that it is normal.

  On the other hand, if there is a failure in the canister 10, even if the positive / negative pressure pump 14 is continuously operated, air flows out from the failure location, and the pressure of the canister 10 does not increase as indicated by the dotted line shown in FIG. Since the pressure is lower than the pressure value obtained by the reference measurement, the controller 40 determines that the failure has occurred.

  Thus, failure diagnosis of the fuel tank 1 and the canister 10 can be performed with a simple device by sequentially applying positive pressure and negative pressure by the positive / negative pressure pump 14. When the pressure drops and becomes constant (F shown in FIG. 8), if the pressure is smaller than the pressure obtained by the reference measurement by the controller 40, it is determined that there is no failure.

It is sectional drawing of the fuel tank of the 1st Embodiment of this invention. It is a graph which shows the change of the internal pressure of a fuel tank and a canister in the failure diagnosis of the 1st implementation of the present invention. It is an expanded sectional view of the canister part of the fuel tank of a 1st embodiment of the present invention. It is an expanded sectional view of a diaphragm valve mechanism and a cut-off valve part of a fuel tank of a 1st embodiment of the present invention. It is a flowchart of the failure diagnosis of the 1st Embodiment of this invention. It is an operation | movement table | surface of the fuel tank components of the 1st Embodiment of this invention. It is sectional drawing of the fuel tank of the 2nd Embodiment of this invention. It is a graph which shows the change of the internal pressure of a fuel tank and a canister in the failure diagnosis of the 2nd implementation of this invention. It is a flowchart of the failure diagnosis of the 2nd Embodiment of this invention. It is an operation | movement table | surface of the fuel tank components of the 2nd Embodiment of this invention. It is sectional drawing of the conventional fuel tank.

Explanation of symbols

1 Fuel tank 10 In-tank canister 14 Positive / negative pressure pump (positive / negative pressure generating means)
15 Pressure sensor (pressure detection means)
16 Solenoid valve (atmosphere blocking means)
17 Pressure detection pipe 18 Orifice 20 Atmospheric introduction part 22 Diaphragm communication pipe 23 Diaphragm valve mechanism (evaporated fuel introduction passage opening / closing means)
23c Canister communication pipe 25 Cut-off valve 34 Purge pipe (purge passage)
40 Controller (Failure diagnosis means)

Claims (12)

A canister disposed in the fuel tank; an evaporative fuel introduction passage for introducing evaporative fuel generated in the fuel tank into the canister; an air introduction passage for introducing air into the canister; In an in-tank canister system failure diagnosis device having a purge passage for introducing evaporated fuel into an intake system of an internal combustion engine,
An air blocking means capable of blocking the air introduction passage;
Positive and negative pressure generating means capable of applying a positive pressure and a negative pressure in the canister;
The evaporative fuel introduction passage opening and closing means for opening and closing the evaporative fuel introduction passage according to positive pressure and negative pressure in the canister;
Pressure detecting means for detecting the pressure in the canister,
Based on the pressure measured by the pressure detecting means, when the evaporative fuel introduction passage is open, it is diagnosed whether the canister and the fuel tank are faulty. When the evaporative fuel introduction passage is closed, the canister A failure diagnosis device for an in-tank canister system comprising the canister for diagnosing whether a failure has occurred and a fuel tank failure diagnosis means. The evaporative fuel introduction passage opening / closing means has two chambers, one chamber communicates with the evaporative fuel introduction passage, the other chamber communicates with the canister, and the evaporative fuel introduction when the inside of the canister is at a negative pressure When the passage is open and the inside of the canister is at a positive pressure, the fuel vapor introduction passage is closed,
The pressure detecting means measures the pressure in the canister and the fuel tank when the evaporated fuel introduction passage is open, and measures the pressure in the canister when the evaporated fuel introduction passage is closed. The failure diagnosis device for an in-tank canister system according to claim 1, wherein the pressure is transmitted to the failure diagnosis means. The evaporative fuel introduction passage opening / closing means has two chambers, one chamber communicating with the evaporative fuel introduction passage, the other chamber communicating with the atmosphere, and the evaporative fuel introduction passage when the inside of the canister is at a positive pressure. Is opened, and when the inside of the canister has a negative pressure, the evaporative fuel introduction passage is closed,
The pressure detecting means measures the pressure in the canister and the fuel tank when the evaporated fuel introduction passage is open, and measures the pressure in the canister when the evaporated fuel introduction passage is closed. The failure diagnosis device for an in-tank canister system according to claim 1, wherein the pressure is transmitted to the failure diagnosis means.   4. The failure diagnosis apparatus for an in-tank canister system according to any one of claims 1 to 3, wherein the evaporative fuel introduction passage opening / closing means opens and closes the evaporative fuel introduction passage by a diaphragm.   5. The in-tank canister system failure diagnosis device according to claim 1, wherein the pressure detection unit includes a reference unit before detecting the pressure in the canister. 6.   In the reference means, the pressure detection means and the positive / negative pressure generator are connected by a pressure detection pipe, one end of the pressure detection pipe is closed by the atmospheric shut-off means, and the inside of the pressure detection pipe is set to a positive pressure or a negative pressure, 6. The failure diagnosis apparatus for an in-tank canister system according to claim 5, wherein the fault diagnosis apparatus is configured to measure pressure by taking air in and out of the pressure detection pipe through an orifice formed in the pressure detection pipe. A canister disposed in the fuel tank; an evaporative fuel introduction passage for introducing evaporative fuel generated in the fuel tank into the canister; an air introduction passage for introducing air into the canister; In an in-tank canister system failure diagnosis method having a purge passage for introducing evaporated fuel into an intake system of an internal combustion engine,
Block the air introduction passage with air blocking means,
A positive or negative pressure is applied to the canister by the positive / negative pressure generator,
The evaporative fuel introduction passage opening / closing means opens and closes the evaporative fuel introduction passage according to the positive pressure and the negative pressure in the canister,
When the evaporative fuel introduction passage is open, the pressure detection means detects the pressure in both the canister and the fuel tank, and the failure diagnosis means diagnoses whether the canister and the fuel tank have failed due to the pressure, A failure diagnosis method for an in-tank canister system, wherein when the evaporative fuel introduction passage is closed, pressure inside the canister is detected by pressure detection means, and the failure diagnosis means diagnoses whether the canister has failed due to pressure. The inside of the canister is made negative by the positive / negative pressure generator,
The evaporative fuel introduction passage opening / closing means configured to have two chambers, one chamber communicating with the evaporative fuel introduction passage, and the other chamber communicating with the canister, is formed by the negative pressure in the canister. Open the evaporative fuel introduction passage,
After making the inside of the canister and the fuel tank negative by the positive / negative pressure generating device, the pressure detecting means simultaneously measures the pressure in the canister and the fuel tank, and sends the pressure to the failure detecting means. Diagnose if the fuel tank has failed,
The inside of the canister is made positive by the positive / negative pressure generator,
The evaporative fuel introduction passage opening / closing means closes the evaporative fuel introduction passage by the positive pressure in the canister,
8. The failure diagnosis method for an in-tank canister system according to claim 7, further comprising failure detection means for diagnosing whether or not a failure has occurred in the canister by sending the pressure of the canister measured by the pressure detection means to the failure detection means. The inside of the canister is made positive by the positive / negative pressure generator,
The evaporative fuel introduction passage opening / closing means configured to have two chambers, one chamber communicating with the evaporative fuel introduction passage, and the other chamber communicating with the canister, is formed by the positive pressure in the canister. Open the evaporative fuel introduction passage,
After making the inside of the canister and the fuel tank positive by the positive / negative pressure generating device, the pressure detecting means simultaneously measures the pressure in the canister and the fuel tank, and sends the pressure to the failure detecting means. Diagnose if the fuel tank has failed,
The inside of the canister is made negative by the positive / negative pressure generator,
The evaporative fuel introduction passage opening / closing means closes the evaporative fuel introduction passage by the negative pressure in the canister,
8. The failure diagnosis method for an in-tank canister system according to claim 7, further comprising failure detection means for diagnosing whether or not a failure has occurred in the canister by sending the pressure of the canister measured by the pressure detection means to the failure detection means.   The in-tank canister according to any one of claims 7 to 9, wherein the evaporative fuel introduction passage opening / closing means opens and closes the evaporative fuel introduction passage by operating a diaphragm by a positive pressure or a negative pressure of the canister. System failure diagnosis method.   11. The method according to claim 7, wherein the pressure of the canister is detected by reference means before detecting the pressure in the canister, and the failure detection means detects a failure based on the result of the pressure of the reference means. The fault diagnosis method for the in-tank canister system described in 1.   In the reference means, the pressure detection means and the positive / negative pressure generator are connected by a pressure detection pipe, one end of the pressure detection pipe is closed by the atmospheric shut-off means, and the inside of the pressure detection pipe is set to a positive pressure or a negative pressure, The fault diagnosis method for an in-tank canister system according to claim 11, wherein pressure is measured by taking air in and out of the pressure detection pipe through an orifice formed in the pressure detection pipe.

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