JP2016089791A - Fuel tank system and fuel tank system anomaly detection method - Google Patents

Abstract

An object of the present invention is to detect clogging of a cross-sectional area reducing portion provided in a tank side bypass passage between a back pressure chamber of a diaphragm valve and a communication pipe on a fuel tank side.
After a pressure is applied to a fuel tank by a pump, a change in the tank internal pressure in a state in which the pump is stopped and an electromagnetic valve is opened is detected, thereby reducing a cross-sectional area reducing portion (orifice portion 64). ) Is detected.
[Selection] Figure 1

Description

  The present invention relates to a fuel tank system and a fuel tank system abnormality detection method.

  A canister side bypass passage is provided between the back pressure chamber of the diaphragm valve installed in the communication pipe between the fuel tank and the canister and the communication pipe on the canister side, and the opening / closing control of the solenoid valve of the canister side bypass passage is based on the tank internal pressure. There is a fuel tank system to perform.

JP2013-144492A

  In the fuel tank system described above, an orifice (cross-sectional area decreasing part) may be provided in the tank side bypass passage between the back pressure chamber of the diaphragm valve and the communication pipe on the fuel tank side. It is desirable to be able to do this.

  In consideration of the above-mentioned fact, the present invention provides a fuel tank system and a fuel tank system capable of detecting clogging of a cross-sectional area reducing portion provided in a tank side bypass passage between a back pressure chamber of a diaphragm valve and a communication pipe on the fuel tank side It is an object to obtain an abnormality detection method.

  In a first aspect of the present invention, a fuel tank that contains fuel, a canister that adsorbs and desorbs evaporated fuel generated in the fuel tank with an adsorbent and has an air communication port, the fuel tank, and the canister A vent pipe communicating with the main tank, a main chamber in which the pressure of the fuel tank acts in the vent pipe, and a back pressure chamber on the opposite side of the main chamber with a diaphragm interposed therebetween, A valve member that opens when the pressure in the main chamber increases and the diaphragm moves, and a tank-side bypass passage that communicates the vent piping from the fuel tank to the main chamber and the back pressure chamber. A canister-side bypass passage communicating the vent pipe from the main chamber to the canister and the back pressure chamber, and a channel cross-sectional area of the tank-side bypass passage A cross-sectional area reducing portion to be reduced, a pump provided at the atmosphere communication port of the canister to apply atmospheric pressure from the canister to the fuel tank through the back pressure chamber, and a tank internal pressure sensor for detecting the tank internal pressure of the fuel tank And a detection member that detects clogging of the cross-sectional area reduction portion due to a change in the tank internal pressure detected by the tank internal pressure sensor from a state in which the air pressure is applied to the fuel tank by the pump.

  In this fuel tank system, the fuel tank and the canister can communicate with each other through a vent pipe.

  Furthermore, this fuel tank system has a tank-side bypass passage and a canister-side bypass passage, and a bypass passage is formed in the vent pipe from the tank-side bypass passage to the canister-side bypass passage through the back pressure chamber. . When the valve member is in the closed state, the vent pipe is closed so as not to communicate.

  The flow path cross-sectional area of the tank side bypass passage is reduced by the cross-sectional area reducing portion. Therefore, it is difficult for the gas to move from the back pressure chamber to the main chamber as compared with the configuration in which the cross-sectional area reducing portion is not provided. That is, it is possible to more reliably maintain a state in which the atmospheric pressure in the back pressure chamber is lower than the atmospheric pressure in the main chamber. When the pressure difference between the back pressure chamber and the main chamber exceeds the valve opening pressure of the valve member, the diaphragm moves to the valve opening position and communicates with the vent pipe.

  The fuel tank system has a detection member. The detection member detects a change in the tank internal pressure from a state in which an air pressure is applied to the fuel tank by a pump. That is, in the state where the cross-sectional area reduced portion is clogged, gas does not easily pass through the cross-sectional area reduced portion compared to the state where the clogged portion is not clogged, so the time change of the tank internal pressure is small. In this way, it is possible to detect clogging of the reduced cross-sectional area from the change time of the tank internal pressure.

  In a 2nd aspect, it has an electromagnetic valve controlled to open and close the said canister side bypass channel in a 1st aspect.

  By closing the solenoid valve provided in the canister-side bypass passage, even if evaporated fuel in the fuel tank flows into the tank-side vent piping, tank-side bypass passage, and back pressure chamber, it moves to the canister. It can be sealed so that it does not.

  When the evaporated fuel in the fuel tank is sent to the canister, the electromagnetic valve is opened. As a result, the canister-side bypass passage is opened, so that the back pressure chamber is opened to the atmosphere. On the other hand, since the tank internal pressure (positive pressure) acts on the main chamber, the pressure in the main chamber becomes relatively higher than the pressure in the back pressure chamber, and the valve member is easy to open. Since the back pressure chamber is opened to the atmosphere in this way, the force required for the operation of the valve member for opening the vent pipe is small compared to the configuration in which the back pressure chamber is not opened to the atmosphere. The pressure is reduced.

  According to a third aspect, in the first or second aspect, a change in the canister internal pressure detected by the canister internal pressure sensor from the state in which the detection member applies the atmospheric pressure to the canister and the fuel tank, and the tank The clogging of the reduced cross-sectional area is detected by comparing changes in internal pressure.

  Since the change in the canister internal pressure is compared with the change in the tank internal pressure, the clogging of the cross-sectional area reduction portion can be appropriately detected as a case where the change in the tank internal pressure is smaller than the change in the canister internal pressure.

  In a fourth aspect, in any one of the first to third aspects, the pump is a negative pressure pump.

  A negative pressure is applied to the canister and the fuel tank using a negative pressure pump. As this negative pressure pump, for example, if a negative pressure pump provided for detecting perforation of a canister or a fuel tank is used, it is unnecessary to add a new negative pressure pump.

  In a fifth aspect, a fuel tank that contains fuel, an evaporative fuel generated in the fuel tank is adsorbed and desorbed by an adsorbent, and a canister having an air communication port is communicated with the fuel tank and the canister A vent pipe, a main chamber in which the pressure of the fuel tank acts in the vent pipe, and a back pressure chamber on the opposite side of the main chamber with a diaphragm interposed therebetween, are divided with respect to the pressure of the back pressure chamber. A valve member that opens when the pressure increases and the diaphragm moves, and that connects the vent pipe; a tank-side bypass passage that connects the vent pipe from the fuel tank to the main chamber and the back pressure chamber; and A canister-side bypass passage that communicates the vent pipe from the main chamber to the canister and the back pressure chamber, and the canister-side bypass passage is opened and closed. An electromagnetic valve, a cross-sectional area reducing portion for locally reducing the cross-sectional area of the tank-side bypass passage, and the fuel tank from the canister through the back pressure chamber provided in the atmosphere communication port of the canister For a fuel tank system having a pump for applying atmospheric pressure to the tank and a tank internal pressure sensor for detecting the tank internal pressure of the fuel tank, after applying pressure to the fuel tank by the pump, the pump is stopped and the pump is stopped. In a state where the canister, the back pressure chamber, and the fuel tank are opened to the atmosphere from the atmosphere communication port, the presence or absence of clogging of the cross-sectional area reducing portion is detected from a change in the tank internal pressure.

  In the fuel tank system according to the fifth aspect, the fuel tank and the canister can communicate with each other through a vent pipe.

  Furthermore, this fuel tank system has a tank-side bypass passage and a canister-side bypass passage, and a bypass passage is formed in the vent pipe from the tank-side bypass passage to the canister-side bypass passage through the back pressure chamber. . When the valve member is in the closed state, the vent pipe is closed so as not to communicate.

  The flow path cross-sectional area of the tank side bypass passage is reduced by the cross-sectional area reducing portion. Therefore, it is difficult for the gas to move from the back pressure chamber to the main chamber as compared with the configuration in which the cross-sectional area reducing portion is not provided. That is, it is possible to more reliably maintain a state in which the atmospheric pressure in the back pressure chamber is lower than the atmospheric pressure in the main chamber. When the pressure difference between the back pressure chamber and the main chamber exceeds the valve opening pressure of the valve member, the diaphragm moves to the valve opening position and communicates with the vent pipe.

  In this fuel tank system abnormality detection method, after applying pressure to the fuel tank by the pump, the pump is stopped and the canister, the back pressure chamber and the fuel tank are opened to the atmosphere from the atmosphere communication port. In the state where the cross-sectional area reduction portion is clogged, gas does not easily pass through the cross-sectional area reduction portion as compared to the state where clogging does not occur, so the time change of the tank internal pressure is small. In this way, it is possible to detect clogging of the reduced cross-sectional area from the change time of the tank internal pressure.

  According to a sixth aspect, in the fifth aspect, the fuel tank system includes a canister internal pressure sensor for detecting a canister internal pressure of the canister, and the clogging of the cross-sectional area reduction portion is detected with respect to the canister and the fuel tank. This is detected by comparing the change in the canister internal pressure from the state where the atmospheric pressure is applied and the change in the tank internal pressure.

  Since the change in the canister internal pressure is compared with the change in the tank internal pressure, clogging of the cross-sectional area reduction portion can be appropriately detected as a case where the change in the tank internal pressure is smaller than the change in the canister internal pressure.

  Since the present invention is configured as described above, it is possible to detect clogging of the cross-sectional area reducing portion provided in the tank side bypass passage between the back pressure chamber of the diaphragm valve and the communication pipe on the fuel tank side.

FIG. 1 is a configuration diagram showing the fuel tank system of the first embodiment. FIG. 2 is a partially enlarged cross-sectional view of the fuel tank system of the first embodiment with the diaphragm valve and the solenoid valve closed. FIG. 3 is a partially enlarged cross-sectional view of the fuel tank system of the first embodiment with the diaphragm valve closed and the solenoid valve closed. FIG. 4 is a partially enlarged cross-sectional view of the fuel tank system of the first embodiment with the diaphragm valve and the solenoid valve opened. FIG. 5 is a flowchart of the fuel tank system abnormality detection method of the first embodiment. 6A and 6B are graphs qualitatively showing changes in the canister internal pressure and FIG. 6B in the tank internal pressure in the fuel tank system abnormality detection method of the first embodiment. 7A and 7B are graphs qualitatively showing changes in the canister internal pressure and FIG. 7B in the tank internal pressure in the fuel tank system abnormality detection method of the first embodiment. FIG. 8 is a graph qualitatively showing changes in the canister internal pressure and (B) in the tank internal pressure in the fuel tank system abnormality detection method of the first embodiment. 9A and 9B are graphs qualitatively showing changes in the canister internal pressure and FIG. 9B in the tank internal pressure in the fuel tank system abnormality detection method of the first embodiment. FIG. 10 is a graph qualitatively showing changes in canister internal pressure and (B) tank internal pressure in the fuel tank system abnormality detection method of the first embodiment. FIG. 11 is a graph qualitatively showing changes in the canister internal pressure and (B) in the tank internal pressure in the fuel tank system abnormality detection method of the first embodiment. FIG. 12 is a graph qualitatively showing changes in the canister internal pressure and (B) in the tank internal pressure in the fuel tank system abnormality detection method of the first embodiment. FIG. 13 is a graph qualitatively showing changes in the canister internal pressure and (B) in the tank internal pressure in the fuel tank system abnormality detection method of the first embodiment. 14A and 14B are graphs qualitatively showing changes in the canister internal pressure and FIG. 14B in the tank internal pressure in the fuel tank system abnormality detection method of the first embodiment. FIG. 15 is a partially enlarged cross-sectional view of the fuel tank system according to the second embodiment with the diaphragm valve and the solenoid valve closed.

  FIG. 1 shows a fuel tank system 12 of the first embodiment. The fuel tank system 12 includes a fuel tank 14 that can store fuel therein.

  A lower portion of an oil supply pipe 82 is connected to the fuel tank 14. The upper end of the oil supply pipe 82 is an oil supply port 16. The refueling person can insert a refueling gun into the refueling port 16 to refuel the fuel tank 14. Except when refueling, the refueling port 16 is closed with a cap 18 for a refueling port, for example.

  The body panel of the automobile is provided with a lid 20 that covers the filler port 16 and the filler port cap 18 from the outside of the vehicle body. The lid 20 is rotated in the direction of arrow R <b> 1 by the control device 32 by operating the lid opener switch 22. In the state where the lid 20 is rotated in the direction of the arrow R1 as described above, the fuel filler cap 18 can be detached from the fuel filler 16 and a fuel gun can be inserted into the fuel filler 16.

  The open / closed state of the lid 20 is detected by the lid open / close sensor 20 </ b> S and sent to the control device 32. In the present embodiment, the state where the lid 20 is opened is regarded as the “fuel supply state to the fuel tank”. As the oil supply state sensor, a sensor for detecting the attachment / detachment state of the oil supply port cap 18 may be used instead of the lid opening / closing sensor 20S.

  A notification device 86 is connected to the control device 32. The notification device 86 notifies, for example, when an abnormality is detected by performing a fuel tank system abnormality detection method described later. As a notification method, for example, notification by a visually recognizable member such as a display or a lamp or a member that notifies by voice may be used. The notification device 86 is provided, for example, in the passenger compartment.

  A fuel pump 24 is provided in the fuel tank 14. The fuel pump 24 and the engine 26 are connected by a fuel supply pipe 28. By driving the fuel pump 24, the fuel in the fuel tank 14 can be sent to the engine 26 through the fuel supply pipe 28.

  The fuel tank 14 is provided with a tank internal pressure sensor 30. The tank internal pressure sensor 30 detects the tank internal pressure of the fuel tank 14 and sends the information to the control device 32.

  The fuel tank system 12 is provided with a canister 34. Inside the canister 34, an adsorbent (activated carbon or the like) capable of adsorbing evaporated fuel is accommodated. The canister 34 and the upper part of the fuel tank 14 are connected by a vent pipe 36. The evaporated fuel generated in the fuel tank 14 is sent to the canister 34 through the vent pipe 36.

  Connected to the canister 34 are a purge pipe 38 that communicates with the engine 26 and an air release pipe 40 that opens the canister 34 to the atmosphere. The negative pressure of the engine 26 can be applied to the canister 34 when the engine 26 is driven. By applying the negative pressure to the canister 34, the evaporated fuel adsorbed by the adsorbent in the canister 34 can be desorbed and sent to the engine 26. At this time, the atmosphere is introduced into the canister 34 through the atmosphere opening pipe 40.

  The canister 34 is provided with a canister internal pressure sensor 84. The canister internal pressure sensor 84 detects the canister internal pressure of the canister 34 and sends the information to the control device 32.

  The air release pipe 40 is provided with a negative pressure pump 42. The negative pressure pump 42 is controlled by the control device 32. The negative pressure pump 42 is used when diagnosing a failure or the like of the fuel tank system 12 by applying a predetermined pressure to the fuel tank system 12 through the canister 34.

  A full tank regulating valve 44 is attached to one end of the vent pipe 36 (the end in the fuel tank 14). When the fuel level in the fuel tank 14 is less than or equal to a predetermined full level, the full tank regulating valve 44 is opened and the evaporated fuel in the fuel tank 14 can be sent to the canister 34. When the fuel liquid level in the fuel tank 14 exceeds a predetermined liquid level (full tank liquid level), the full tank regulating valve 44 is closed. Thereby, the evaporated fuel in the fuel tank 14 does not flow to the canister 34. In this state, when fuel is further supplied into the fuel tank 14, the fuel ascends the fuel supply pipe 82 and reaches the fuel supply gun. When the auto-stop function of the refueling gun is activated, refueling is stopped.

  A diaphragm valve 46 is provided at an intermediate portion of the vent pipe 36 (a portion between the fuel tank 14 and the canister 34). The diaphragm valve 46 is an example of the valve member of the present invention. Hereinafter, the vent pipe 36 on the fuel tank side from the diaphragm valve 46 is referred to as a tank side vent pipe 36T, and the vent pipe 36 on the canister 34 side from the diaphragm valve 46 is referred to as a canister side vent pipe 36C.

  As shown in detail in FIG. 2, the diaphragm valve 46 has a valve housing 48 in which the other end side of the tank side vent pipe 36 </ b> T is expanded in a flat cylindrical shape. Inside the valve housing 48, one end side of the canister side vent pipe 36 </ b> C is accommodated so as to be coaxial with the valve housing 48, and a valve seat 50 is configured. A portion between the valve seat 50 and the valve housing 48 is a main chamber 52. As can be seen from FIG. 1, the main chamber 52 communicates with the inside of the fuel tank 14 through the tank side vent pipe 36T.

  The opening at the upper end of the valve seat 50 can be closed by the valve member main body 54 of the diaphragm 56. The outer peripheral portion of the diaphragm 56 is fixed to the inner peripheral surface of the valve housing 48. The space above the diaphragm 56 in FIG. 2 is a back pressure chamber 58. Therefore, the main chamber 52 and the back pressure chamber 58 are partitioned by the diaphragm 56.

  As for the area (pressure receiving area) where the diaphragm 56 (including the valve member main body 54) receives pressure, the pressure receiving area on the back pressure chamber 58 side is larger in cross-sectional area of the valve seat 50 than the pressure receiving area on the main chamber 52 side. It ’s getting wider by the minute.

  A compression coil spring 60 is accommodated in the back pressure chamber 58. The compression coil spring 60 applies a predetermined spring force to the diaphragm 56 in the direction toward the valve seat 50 (arrow S1 direction). Further, the outer edge portion of the diaphragm 56 applies a predetermined spring force in the direction of the arrow S <b> 1 to the valve member main body 54. Thereby, the valve member main body 54 is urged in a direction to close the opening portion of the valve seat 50. For example, when the internal pressure of the main chamber 52 and the internal pressure of the back pressure chamber 58 are approximately the same, the valve member main body 54 is in close contact with the opening portion of the valve seat 50. As a result, the diaphragm valve 46 is closed, and movement of gas in the vent pipe 36 is prevented.

  On the other hand, for example, when the back pressure chamber 58 becomes a predetermined negative pressure or higher than the main chamber 52 (in which the internal pressure is low), the valve member main body 54 moves against the spring force of the compression coil spring 60 and the diaphragm 56. It moves to the pressure chamber 58 side, and the opening part of the valve seat 50 is opened. Thereby, the diaphragm valve 46 is opened, and gas can be moved in the vent pipe 36.

  A tank-side bypass passage 62 is provided between the tank-side vent pipe 36T and the back pressure chamber 58. Gas can move between the fuel tank 14 and the back pressure chamber 58 through the tank side bypass passage 62.

  The tank side bypass passage 62 is provided with an orifice 64 having a locally reduced inner diameter. The orifice 64 provides a predetermined resistance to gas movement between the fuel tank 14 and the back pressure chamber 58. The orifice 64 is an example of the cross-sectional area reducing portion of the present invention.

  As described above, as a means for generating a predetermined resistance to gas movement between the fuel tank 14 and the back pressure chamber 58, an orifice 64 (a structure in which the tank-side bypass passage 62 is locally reduced in diameter) is used. It is not limited. For example, the inner diameter of the tank-side bypass passage 62 may be reduced as a whole to cause a predetermined resistance to gas movement. Furthermore, the tank-side bypass passage 62 may be bent at a predetermined position (may be bent or curved) to cause a predetermined resistance to gas movement.

  A canister-side bypass passage 66 is provided between the canister-side vent pipe 36 </ b> C and the back pressure chamber 58. An electromagnetic valve 68 is provided at an intermediate portion of the canister side bypass passage 66.

  The solenoid valve 68 has a solenoid valve housing 70. In the electromagnetic valve housing 70, a coil portion 72 that is energized and controlled by the control device 32, a plunger portion 74 that moves in the arrow S2 direction and the opposite direction in response to a driving force from the coil portion 72, and a plunger portion A disc-shaped solenoid valve main body 76 provided at the tip of 74 is provided. Further, a part (intermediate part) of the canister-side bypass passage 66 passes through the electromagnetic valve housing 70.

  The electromagnetic valve body 76 closes the canister-side bypass passage 66 in a state where the solenoid valve body 76 is in contact with a valve seat 78 provided in the canister-side bypass passage 66. On the other hand, as shown in FIG. 3, when the solenoid valve body 76 is separated from the valve seat 78, the gas can move through the canister-side bypass passage 66.

  A compression coil spring 80 is attached to the plunger portion 74. The compression coil spring 80 applies a predetermined spring force to the electromagnetic valve main body 76 in the direction of the arrow S2 so that the electromagnetic valve main body 76 is not inadvertently separated from the valve seat 78. However, when the positive pressure applied from the back pressure chamber 58 becomes equal to or greater than a predetermined value, the compression coil spring 80 moves so that the solenoid valve body 76 moves in the direction opposite to the arrow S1 without energizing the coil portion 72. The spring force is set to a predetermined value.

  Next, the operation of the fuel tank system 12 of this embodiment will be described.

  In the fuel tank system 12 of the present embodiment, in a normal state, that is, in a state where the fuel tank 14 is not refueled (the vehicle may be traveling or parked), as shown in FIG. The solenoid valve body 76 of the solenoid valve 68 is closed. The valve member main body 54 of the diaphragm valve 46 is also closed. That is, the fuel tank 14 is in a sealed state so that the evaporated fuel inside does not move to the canister 34. For this reason, the tank internal pressure of the fuel tank 14 acts on both the main chamber 52 and the back pressure chamber 58 of the diaphragm valve 46. The diaphragm valve 46 is maintained in a closed state by the spring force of the compression coil spring 60 and the diaphragm 56 and is not opened carelessly.

  When the lid opener switch 22 is operated at the time of fuel supply, the control device opens the lid 20. Further, the control device 32 opens the electromagnetic valve 68 as shown in FIG. As a result, the back pressure chamber 58 of the diaphragm valve 46 is opened to the atmosphere from the atmosphere opening pipe 40 through the canister 34, the canister side vent pipe 36 </ b> C, and the canister side bypass passage 66. That is, the pressure in the back pressure chamber 58 decreases and approaches atmospheric pressure.

  On the other hand, the main chamber 52 is also opened to the atmosphere from the back pressure chamber 58 through the tank side bypass passage 62 and the tank side vent pipe 36T. However, it takes a longer time than the back pressure chamber 58 for the main chamber 52 to have the same pressure as the back pressure chamber 58. That is, the pressure difference is generated between the back pressure chamber 58 and the main chamber 52 (the pressure in the back pressure chamber 58 is lower than that in the main chamber 52). Therefore, the diaphragm valve 46 can be opened with a smaller valve opening pressure as compared with a configuration in which such a pressure difference does not occur between the back pressure chamber 58 and the main chamber 52. Thereby, as shown in FIG. 4, the valve member main body 54 moves to the back pressure chamber 58 side (upper side), and the diaphragm valve 46 is opened.

  In the first embodiment, the valve member main body 54 of the diaphragm valve 46 can be increased in size, whereas the electromagnetic valve main body 76 of the electromagnetic valve 68 does not need to exhibit the action of opening and closing the vent pipe 36 (valve seat 50). Can be downsized. Since the area of the electromagnetic valve body 76 that receives the tank internal pressure of the fuel tank 14 is also reduced, the pressing load (load in the direction of arrow S2 in FIG. 2) necessary for closing the electromagnetic valve 68 can be reduced. As a result, the electromagnetic valve 68 can be reduced in size and power consumption, and the fuel tank system 12 having low cost and excellent fuel efficiency can be obtained.

  Before refueling, the diaphragm valve 46 is opened, so that the tank internal pressure of the fuel tank 14 is reduced. In the present embodiment, by reducing the ventilation resistance of the vent pipe 36, the time required for lowering the tank internal pressure is shortened, and refueling in a shorter time becomes possible.

  When the vehicle is running, as shown in FIG. 1, when the tank internal pressure detected by the tank internal pressure sensor 30 does not exceed a predetermined value, the control device 32 closes the electromagnetic valve 68 as shown in FIG. doing. Since the diaphragm valve 46 is also closed, the fuel tank 14 is sealed. The evaporated fuel generated in the fuel tank 14 does not move to the canister 34.

  When the tank internal pressure exceeds a predetermined value, the control device 32 opens the electromagnetic valve 68 (the same state as in FIG. 3). The evaporated fuel can move from the tank side vent pipe 36T to the canister 34 through the tank side bypass passage 62, the back pressure chamber 58, the canister side bypass passage 66, and the canister side vent pipe 36C. Then, by appropriately opening and closing the electromagnetic valve 68, it is possible to control the flow rate of the evaporated fuel flowing through the vent pipe 36 and the tank internal pressure.

  Even when the vehicle is parked, the solenoid valve 68 and the diaphragm valve 46 are normally closed, and the evaporated fuel in the fuel tank 14 does not move to the canister 34.

  Next, an abnormality detection method in the fuel tank system 12 of the first embodiment will be described. This abnormality detection includes two types of perforation detection, “canister perforation” and “fuel tank perforation”, and detection of orifice clogging. Actually, in the detection of “canister perforation”, a path from the engine 26 (strictly, a purge valve that opens and closes in response to the purge of the canister 34) to the electromagnetic valve 68 and the diaphragm valve 46 through the canister 34. Detect perforations. In the detection of “perforation of the fuel tank”, perforation of the path from the electromagnetic valve 68 and the diaphragm valve 46 to the fuel tank 14 and the fuel supply pipe 82 is detected.

  As shown in FIG. 5, in this abnormality detection flow, first, in step S102, the electromagnetic valve 68 is opened and the negative pressure pump 42 is stopped. As a result, the atmosphere is introduced into the canister 34, the back pressure chamber 58 and the fuel tank 14. The canister internal pressure is in a state close to atmospheric pressure as shown by a one-dot chain line CP in FIG. Similarly, the tank internal pressure is also close to the atmospheric pressure as shown by a two-dot chain line TP in FIG.

  Next, in step S104, the electromagnetic valve 68 is closed and the negative pressure pump 42 is driven. At this time, if the electromagnetic valve 68 is securely closed, the negative pressure acts on the canister 34 but does not act on the fuel tank 14. That is, the canister internal pressure gradually decreases as shown by a one-dot chain line CP in FIG. 7A, whereas the tank internal pressure does not change as shown by a two-dot chain line TP in FIG. 7B (close to atmospheric pressure). State).

  In step S106, it is determined whether or not the canister internal pressure has decreased. As a determination criterion, a negative pressure reference value (a specific value indicated by a broken line DP) is set, and determination can be made based on whether or not the reference value is lower.

  As shown by a one-dot chain line CP in FIG. 8A, when it is determined that the canister internal pressure has not decreased, it is considered that the canister 34 is perforated. The control device 32 proceeds to step S122, and the notification device 86 notifies the perforation of the canister 34. At this time, as indicated by a two-dot chain line TP in FIG. 8B, the tank internal pressure does not change and is maintained in a state close to the atmospheric pressure.

  If the control device 32 determines in step S106 that the canister internal pressure has decreased (see the one-dot chain line CP in FIG. 9A), the control device 32 proceeds to step S108. And the control apparatus 32 judges whether the tank internal pressure fell. That is, when the control device 32 performs the valve closing control (transmission of an electric signal for instructing the valve closing) in Step S104, the tank internal pressure is decreased (see FIG. 9B). It is considered that the negative pressure of the negative pressure pump 42 acts on the fuel tank 14 (see the dotted line TP). And as the cause, it is thought that the diaphragm valve 46 or the electromagnetic valve 68 is stuck in the opened state. Then, the control apparatus 32 transfers to step S124, and notifies that the diaphragm valve 46 or the electromagnetic valve 68 is stuck in the open state (open sticking) by the notifying device 86.

  If the control device 32 determines in step S108 that the tank internal pressure has not decreased, the control device 32 proceeds to step S110, opens the electromagnetic valve 68, and stops the negative pressure pump 42. Since the atmosphere is introduced into the canister 34, the back pressure chamber 58, and the fuel tank 14, the internal pressure of the canister 34 and the fuel tank 14 becomes atmospheric pressure (or a state close to atmospheric pressure) again.

  In step S112, the control device 32 opens the electromagnetic valve 68 and drives the negative pressure pump 42. Then, in step S114, control device 32 determines whether or not the canister internal pressure has decreased. That is, in step S106, it is determined that the canister internal pressure has not been reduced and the canister 34 has not been perforated. Therefore, if there is no perforation in the fuel tank 14, FIG. 10 (A) and FIG. As shown in FIG. 10B, both the canister internal pressure and the tank internal pressure decrease.

  When the control device 32 determines in step S114 that the internal pressure of the canister does not decrease (maintains a state close to the atmospheric pressure) as indicated by a one-dot chain line CP in FIG. 11A, the fuel tank 14 It seems that there is a hole in the hole. Therefore, in this case, the control device 32 proceeds to step S126 and notifies the perforation of the fuel tank 14 by the notification device 86. In this state, as indicated by a two-dot chain line TP in FIG. 11B, the tank internal pressure does not decrease (maintains a state close to atmospheric pressure).

  If the control device 32 determines in step S114 that the canister internal pressure has decreased as indicated by the alternate long and short dash line CT in FIG. 12A, then in step S116, whether or not the tank internal pressure is atmospheric pressure. Judging. Here, it is assumed that the tank internal pressure is atmospheric pressure as indicated by a two-dot chain line TP in FIG. 12B, although it is determined in step S114 that the fuel tank 14 is not perforated. It is close to the state. In this case, it is considered that the electromagnetic valve 68 is fixed in a closed state, and the negative pressure of the negative pressure pump 42 does not act on the fuel tank 14. Therefore, in this case, the control device 32 causes the control device 32 to proceed to step S128 and notifies the notification device 86 that the electromagnetic valve 68 is fixed in the closed state (closed fixation).

  Here, it is assumed that the orifice 64 is clogged. In this case, when the negative pressure of the negative pressure pump 42 acts on the back pressure chamber 58 by opening the electromagnetic valve 68, the diaphragm valve 46 is temporarily opened. However, when the main chamber 52 also becomes negative pressure due to the opening of the diaphragm valve 46, the diaphragm valve 46 is closed. When the diaphragm valve 46 is repeatedly opened and closed in this manner, as a result, a sufficient amount of gas flows through the vent pipe 36 in a certain amount of time, so that the tank internal pressure becomes negative. That is, since it is determined in step S116 that the tank internal pressure is not atmospheric pressure, if this flow is finished as it is, clogging of the orifice 64 cannot be detected.

  Therefore, in the present embodiment, when it is determined in step S116 that the tank internal pressure is negative as shown in FIG. 12B, the control device 32 proceeds to step S118 and opens the electromagnetic valve 68. At the same time, the negative pressure pump 42 is stopped. As a result, as indicated by a one-dot chain line CP in FIG. 13A, the internal pressure of the canister rises in a short time and becomes close to atmospheric pressure.

  If the orifice 64 is not clogged, the fuel tank 14 is also opened to the atmosphere. Therefore, as shown by a two-dot chain line TP in FIG. 13B, the tank internal pressure rises in a short time, similar to the canister internal pressure. Conceivable.

  In step S120, the control device 32 determines whether or not the increase rate of the tank internal pressure is slow. As indicated by a two-dot chain line TP in FIG. 14B, when the rate of increase of the tank internal pressure is slow, it is considered that the orifice 64 is clogged. Therefore, the control device 32 proceeds to step S130, and the orifice 64 Is notified by the notification device 86. On the other hand, if it is determined in step S120 that the increase rate of the tank internal pressure is fast, the control device 32 ends this flow.

  Note that the criterion for determining the rate of increase of the tank internal pressure in step S120 is not particularly limited. For example, as shown in FIG. 14 (A), it can be considered that the increase speed of the canister internal pressure is fast. Therefore, when the increase speed of the tank internal pressure is slower than the canister internal pressure, the process may proceed to step S130.

  Alternatively, the increase rate of the tank internal pressure when the orifice 64 is not clogged may be measured in advance, and a threshold value for the increase rate of the tank internal pressure may be set based on this measurement speed. For example, FIG. A broken line DL shown in FIG. 4 is a threshold value of the rising speed of the tank internal pressure determined in this way. Then, when the rate of increase of the tank internal pressure is slower than this threshold (the gradient of the tank internal pressure TP is gentle in FIG. 14B), the configuration may be shifted to step S130.

  As can be seen from the above description, when the control device 32 does not perform steps S118 and S120, even if the orifice 64 is clogged, this clogging cannot be detected. In the tank abnormality detection method of this embodiment, the presence or absence of clogging of the orifice 64 can be detected by executing step S118 and performing the determination in step S120.

  Next, a second embodiment will be described. In the second embodiment, elements, members, and the like that are the same as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. The overall configuration of the fuel tank system of the second embodiment is also the same as that of the fuel tank system of the first embodiment, and is not shown.

  In the second embodiment, as shown in FIG. 15, a relief hole 90 is formed in the partition wall between the canister side vent pipe 36C and the main chamber 52 (or the tank side vent pipe 36T). A positive pressure relief valve 92 for opening and closing the relief hole 90 is provided in the canister side vent pipe 36C.

  The positive pressure relief valve 92 includes a relief valve body 94 that opens and closes the relief hole 90 and a spring 96 that biases the relief valve body 94 to the closed position. Even if the tank internal pressure of the fuel tank 14 is positive, if the pressure is below a predetermined value, the relief valve body 94 is in the closed position and the relief hole 90 is closed by the biasing force of the spring 96. However, when the tank internal pressure exceeds a predetermined value, the relief valve main body 94 moves to the open position against the biasing force of the spring 96. Thereby, since the gas in the fuel tank 14 flows from the main chamber 52 (or the tank side vent pipe 36T) to the canister side vent pipe 36C, it is suppressed that the tank internal pressure rises excessively.

  Also in the second embodiment, the abnormality of the fuel tank system can be detected by the same abnormality detection method as in the first embodiment. In particular, the negative pressure may act on a part or all of the path from the canister 34 to the fuel tank 14 by driving the negative pressure pump 42. However, the valve opening pressure of the positive pressure relief valve 92 is set so that the positive pressure relief valve 92 is not opened carelessly by this negative pressure.

  As a pump used for detecting an abnormality in the fuel tank system, a negative pressure pump is exemplified above, but a positive pressure pump may be used, for example. When using a negative pressure pump, as can be seen from the above description, even when detecting holes in the canister or fuel tank, it is possible to efficiently detect these holes by applying negative pressure to the canister or fuel tank. . In other words, it is possible to detect the clogging of the orifice 64 by effectively using the negative pressure pump used for detecting the perforation of the canister or the fuel tank, and it is not necessary to add a new pump.

  In the above, the fuel tank system 12 including the electromagnetic valve 68 has been illustrated. However, in order to detect clogging of the orifice 64, a fuel tank system without the electromagnetic valve 68 may be used. That is, if a negative pressure is applied to the fuel tank 14 by driving the negative pressure pump 42 and then the negative pressure pump 42 is stopped, the clogging of the orifice 64 can be detected from the change in the tank internal pressure.

  When the electromagnetic valve 68 is provided in the canister-side bypass passage 66, the movement of the evaporated fuel in the fuel tank 14 to the canister 34 can be suppressed by closing the canister-side bypass passage 66. The back pressure chamber 58 can be opened to the atmosphere by opening the electromagnetic valve 68.

DESCRIPTION OF SYMBOLS 12 Fuel tank system 14 Fuel tank 24 Fuel pump 26 Engine 30 Tank internal pressure sensor 32 Control apparatus (detection member)
34 Canister 36 Vent Piping 36C Canister Side Vent Piping 36T Tank Side Vent Piping 38 Purge Piping 40 Atmospheric Release Piping 42 Negative Pressure Pump (Pump)
46 Diaphragm valve 52 Main chamber 54 Valve member body 56 Diaphragm 58 Back pressure chamber 62 Tank side bypass passage 64 Orifice 66 Canister side bypass passage 68 Solenoid valve 84 Canister internal pressure sensor

Claims (6)

A fuel tank containing fuel;
Adsorbing and desorbing the evaporated fuel generated in the fuel tank with an adsorbent, and a canister having an air communication port;
A vent pipe communicating the fuel tank and the canister;
The vent pipe is divided into a main chamber on which the pressure of the fuel tank acts and a back pressure chamber on the opposite side of the main chamber with a diaphragm interposed therebetween, and the pressure of the main chamber is higher than the pressure of the back pressure chamber. A valve member that opens when the diaphragm moves and communicates the vent pipe;
A tank side bypass passage communicating the vent pipe from the fuel tank to the main chamber and the back pressure chamber;
A canister-side bypass passage communicating the vent pipe and the back pressure chamber from the main chamber to the canister;
A cross-sectional area decreasing portion for reducing the cross-sectional area of the tank-side bypass passage;
A pump that is provided at the atmosphere communication port of the canister and applies atmospheric pressure to the fuel tank from the canister via the back pressure chamber;
A tank internal pressure sensor for detecting a tank internal pressure of the fuel tank;
A detection member that detects clogging of the cross-sectional area reduction portion due to a change in the tank internal pressure detected by the tank internal pressure sensor from a state in which the air pressure is applied to the fuel tank by the pump;
Having fuel tank system.   The fuel tank system according to claim 1, further comprising an electromagnetic valve controlled to open and close the canister-side bypass passage. A canister internal pressure sensor for detecting the canister internal pressure of the canister;
By comparing the change in the canister internal pressure detected by the canister internal pressure sensor with the change in the tank internal pressure from the state in which the detection member applies the atmospheric pressure to the canister and the fuel tank, the cross-sectional area reducing portion is clogged. The fuel tank system according to claim 1 or 2, wherein the fuel tank system is detected.   The fuel tank system according to any one of claims 1 to 3, wherein the pump is a negative pressure pump. A fuel tank containing fuel;
Adsorbing and desorbing the evaporated fuel generated in the fuel tank with an adsorbent, and a canister having an air communication port;
A vent pipe communicating the fuel tank and the canister;
The vent pipe is divided into a main chamber on which the pressure of the fuel tank acts and a back pressure chamber on the opposite side of the main chamber with a diaphragm interposed therebetween, and the pressure of the main chamber is higher than the pressure of the back pressure chamber. A valve member that opens when the diaphragm moves and communicates the vent pipe;
A tank side bypass passage communicating the vent pipe from the fuel tank to the main chamber and the back pressure chamber;
A canister-side bypass passage communicating the vent pipe and the back pressure chamber from the main chamber to the canister;
A solenoid valve controlled to open and close the canister-side bypass passage;
A cross-sectional area reducing portion for locally reducing the flow path cross-sectional area of the tank-side bypass passage;
A pump that is provided at the atmosphere communication port of the canister and applies atmospheric pressure to the fuel tank from the canister via the back pressure chamber;
A tank internal pressure sensor for detecting a tank internal pressure of the fuel tank;
For fuel tank systems with
After the pressure is applied to the fuel tank by the pump, the pump is stopped and the canister, the back pressure chamber and the fuel tank are opened to the atmosphere from the atmosphere communication port, and the disconnection from the change in the tank internal pressure is performed. A fuel tank system abnormality detection method for detecting the presence or absence of clogging in an area reduction part. The fuel tank system has a canister internal pressure sensor for detecting the canister internal pressure of the canister;
6. The fuel tank system abnormality detection according to claim 5, wherein clogging of the cross-sectional area reduction portion is detected by comparing a change in canister internal pressure and a change in tank internal pressure from a state in which the atmospheric pressure is applied to the canister and the fuel tank. Method.