JP5849713B2 - Fuel tank system - Google Patents

Description

  The present invention relates to a fuel tank system.

  Patent Document 1 describes an evaporative fuel discharge suppression device in which an electromagnetic block valve (open / close valve) is disposed on an evaporation line from a fuel tank to a canister. In the configuration described in this document, a closed fuel tank system can be configured by completely closing the evaporation line by a blocking valve.

  In the fuel tank system having the above-described structure, when the negative pressure pump is driven, negative pressure may be applied to the fuel tank via the canister and the blocking valve to detect the perforation of the fuel tank.

  In such a fuel tank system, it is desired to suppress a gas containing a large amount of evaporated fuel from flowing into the canister in a short time when the perforation detection is performed in a state where the tank internal pressure of the fuel tank is high. .

JP 2005-104394 A

  In view of the above facts, the present invention provides a fuel tank system capable of suppressing a gas containing a large amount of evaporated fuel from flowing into a canister in a short time when perforation detection is performed in a state where the tank internal pressure of the fuel tank is high. It is a problem to obtain.

According to the first aspect of the present invention, a fuel tank that can accommodate fuel therein, a canister that adsorbs and desorbs evaporated fuel generated in the fuel tank with an adsorbent, and the interior of the canister is opened to the atmosphere. A vent pipe for communicating the fuel tank and the canister with each other, a vent pipe for sending evaporated fuel in the fuel tank to the canister, and a tank internal pressure of the fuel tank acting on the vent pipe The main chamber is divided into a back pressure chamber on the opposite side of the main chamber with the valve member body interposed therebetween, and the valve opens when the pressure of the main chamber becomes higher than the pressure of the back pressure chamber and the valve member body moves. A valve member capable of communicating with the vent pipe, a tank-side bypass passage for guiding the tank internal pressure of the fuel tank to the back pressure chamber, and for opening the back pressure chamber to the atmosphere via the canister An air release channel, an electromagnetic valve capable of opening and closing the atmosphere release channel, and a negative pressure capable of applying a negative pressure in the fuel tank from the atmosphere release tube side than the valve member through the vent pipe A pump, a tank internal pressure sensor for detecting the tank internal pressure of the fuel tank, a back pressure chamber pressure sensor for detecting the pressure of the back pressure chamber , and driving of the negative pressure pump for detecting perforation of the fuel tank. and control, have a, a control unit for control and the opening and closing of the electromagnetic valve based on the tank internal pressure detected by the tank internal pressure sensor, said control device, said negative for perforated sensing When the tank internal pressure exceeds a preset positive pressure threshold during driving of the pressure pump, the pressure difference between the tank internal pressure and the back pressure chamber internal pressure is controlled by opening and closing the solenoid valve. Is the valve member When the pressure in the main chamber does not become so high that the valve member opens with respect to the pressure in the back pressure chamber so that the pressure in the tank is less than the valve opening pressure, and the tank internal pressure is less than or equal to a preset positive pressure threshold Keeps the solenoid valve open .

  In this fuel tank system, the fuel tank and the canister can communicate with each other by a vent pipe, but the tank internal pressure of the fuel tank is guided to the back pressure chamber by the tank side bypass passage. The vent pipe is blocked by the valve member so as not to communicate, and the solenoid valve provided in the canister-side bypass passage is closed so that the evaporated fuel in the fuel tank can be sealed so as not to move to the canister. .

When a large amount of evaporated fuel in the fuel tank is sent to the canister, when the control device opens the electromagnetic valve, the air release passage is opened, and 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 is relatively higher than the pressure in the back pressure chamber. Compared with the configuration in which the back pressure chamber is not opened to the atmosphere, the force required for the operation of the valve member for opening the vent pipe is small. The valve opening pressure of the valve member is reduced.

  The tank internal pressure of the fuel tank is detected by a tank internal pressure sensor. When detecting a hole in the fuel tank, the control device introduces a negative pressure into the fuel tank by driving the negative pressure pump. By detecting the tank internal pressure of the fuel tank at this time with a tank internal pressure sensor, it is possible to detect a hole in the fuel tank. This perforation detection is performed not only on the fuel tank but also on piping connected to the fuel tank (hereinafter referred to as “fuel tank system”), and is simply referred to as “perforation detection”. Sometimes it means perforation detection for the fuel tank system.

In addition, when the tank internal pressure exceeds the positive pressure threshold, the control device ensures that the differential pressure between the main chamber and the back pressure chamber is equal to or lower than the valve opening pressure of the valve member while the negative pressure pump is being driven. Open / close control of solenoid valve. The valve member is not opened, and the gas in the fuel tank is removed from the fuel tank when the solenoid valve is open. The tank side vent pipe, the tank side bypass passage, the back pressure chamber, the air release channel, and the canister side Since it moves to the canister via the vent pipe, it does not flow into the canister in large quantities.

When the tank internal pressure is equal to or lower than the positive pressure threshold, the control device opens the electromagnetic valve while the negative pressure pump is being driven . As a result, the back pressure chamber is opened to the atmosphere and the valve member is opened, so that the gas in the fuel tank not only passes through the solenoid valve but also passes through the valve member and the canister side vent pipe from the tank side vent pipe. Even in the path, it flows into the canister. Therefore, a desired negative pressure can be introduced into the fuel tank in a short time.

According to a second aspect of the present invention, in the first aspect of the present invention, while the negative pressure is introduced into the fuel tank by driving the negative pressure pump, the internal pressure of the tank falls below a preset perforation determination threshold. The controller determines that the fuel tank is not perforated.

  That is, if there is a hole in the fuel tank system, even if negative pressure is introduced into the fuel tank system by driving the negative pressure pump, the air flows from the hole, so the pressure drop in the fuel tank system is less than expected. . Using this, when the tank internal pressure falls below a preset perforation determination threshold, it can be determined that there is no perforation in the fuel tank system.

According to a third aspect of the present invention, in the first or second aspect of the present invention, when the negative pressure pump is driven and the tank internal pressure does not decrease, the control device causes the electromagnetic valve to malfunction. It is determined that

  That is, if the solenoid valve is opened, the pressure of the fuel tank is reduced by driving the negative pressure pump. On the other hand, if the tank pressure does not decrease even when the negative pressure pump is driven, it is considered that the solenoid valve is not opened. In this way, the control device can determine that the solenoid valve is malfunctioning.

  Since the present invention is configured as described above, it is possible to suppress a gas containing a large amount of evaporated fuel from flowing into the canister in a short time when the perforation detection is performed in a state where the tank internal pressure of the fuel tank is high.

1 is a schematic diagram illustrating an overall configuration of a fuel tank system according to a first embodiment of the present invention. FIG. 3 is a partially enlarged cross-sectional view of the fuel tank system according to the first embodiment of the present invention with a diaphragm valve and a solenoid valve closed. It is sectional drawing which expands partially and shows a state with the diaphragm valve closed and the solenoid valve opened in the fuel tank system of 1st Embodiment of this invention. It is sectional drawing shown in the state which the diaphragm valve and the solenoid valve opened in the fuel tank system of 1st Embodiment of this invention. It is sectional drawing which expands partially and shows the state which the diaphragm valve opened in the fuel tank system of 1st Embodiment of this invention, and the solenoid valve closed. FIG. 3 is a partially enlarged cross-sectional view showing a state where a solenoid valve is opened and a diaphragm valve is closed when a hole is detected in the fuel tank system of the first embodiment of the present invention. It is sectional drawing which expands partially and shows a state with the solenoid valve and the diaphragm valve opening at the time of perforation detection in the fuel tank system of 1st Embodiment of this invention. It is a graph which shows qualitatively the relation between the valve opening time of the solenoid valve in the fuel tank system of a 1st embodiment of the present invention, and the pressure difference of a main room and a back pressure room. It is a graph which shows qualitatively the relationship between the elapsed time at the time of perforation detection, and the tank internal pressure in the fuel tank system of a 1st embodiment of the present invention. It is a flowchart which shows control of the perforation detection in the fuel tank system of 1st Embodiment of this invention. It is sectional drawing which expands partially and shows in a state where the diaphragm valve and the solenoid valve closed in the fuel tank system of the 1st modification of 1st Embodiment of this invention. It is sectional drawing which expands partially and shows a state with the diaphragm valve and the solenoid valve closed in the fuel tank system of the 2nd modification of 1st Embodiment of this invention.

  FIG. 1 shows a fuel tank system 12 according to a first embodiment of the present invention. 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, and an oil supply gun can be inserted into the oil supply port 16 to supply oil to 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 in which the lid 20 is opened is regarded as the “fuel supply state to the fuel tank”, and the lid opening / closing sensor 20S is an example of a fuel supply state sensor. 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 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 gas containing 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. When the engine 26 is driven, the evaporated fuel adsorbed by the adsorbent in the canister 34 can be desorbed and sent to the engine 26 by applying the negative pressure of the engine 26. At this time, the atmosphere is introduced into the canister 34 through the atmosphere opening pipe 40.

  The air release pipe 40 is provided with a diagnostic pump 42. The driving of the diagnostic pump 42 is controlled by the control device 32. The diagnostic 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 from the canister 34 through the vent pipe 36. In particular, in the present embodiment, a negative pressure is applied to the fuel tank 14 and a closed system (fuel tank system) including piping connected to the fuel tank 14 so that a hole is formed in the fuel tank system as will be described later. It is set as the structure which can be detected, and is an example of the negative pressure pump which concerns on this invention.

  The position of the diagnostic pump 42 (negative pressure pump) is not limited to the atmosphere opening pipe 40, and a negative pressure is introduced into the fuel tank 14 through the vent pipe 36 from the atmosphere opening pipe 40 side rather than the diaphragm valve 46. I can do it. For example, it may be provided in the canister side vent pipe 36 </ b> C between the diaphragm valve 46 and 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 below a predetermined full level, the full tank regulating valve 44 is opened, and the gas containing 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 gas 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 with respect to the diaphragm valve 46 is referred to as a tank side vent pipe 36T and the vent pipe 36 on the canister 34 side with respect to the diaphragm valve 46 is referred to as a canister side vent pipe 36C. The tank side bypass passage 36 </ b> T has a function of guiding the tank internal pressure of the fuel tank to the back pressure chamber 58.

  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 can communicate 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. The periphery of the valve member main body 54 is fixed to the inner peripheral surface of the valve housing 48 by a diaphragm 56. The space above the valve member main body 54 and 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.

  The area (pressure receiving area) where the valve member main body 54 and the diaphragm 56 receive pressure is such that the pressure receiving area on the back pressure chamber 58 side is equal to the cross sectional area of the valve seat 50 than the pressure receiving area on the main chamber 52 side. It is getting wider.

  A compression coil spring 60 is accommodated in the back pressure chamber 58. The compression coil spring 60 applies a predetermined spring force in the direction toward the valve seat 50 (arrow S1 direction) to the valve member main body 54. Further, the diaphragm 56 also applies a predetermined spring force in the direction of the arrow S1 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. As a result, 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 a reduced diameter portion 64 having a locally reduced inner diameter. Due to the reduced diameter portion 64, a predetermined resistance is generated in the movement of the gas between the fuel tank 14 and the back pressure chamber 58.

  As described above, the means for causing the gas between the fuel tank 14 and the back pressure chamber 58 to generate a predetermined resistance is not limited to a structure in which the tank-side bypass passage 62 is locally reduced in diameter. 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 that is controlled to be opened and closed by the control device 32 is provided in 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. In the present embodiment, the direction in which the solenoid valve main body 76 moves away from the valve seat 78, that is, the moving direction of the solenoid valve main body 76 when opening the canister-side bypass passage 66 is a direction in which positive pressure from the back pressure chamber 58 is received. The direction of the solenoid valve main body 76 is set so as to match.

  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 body 76 in the direction of the arrow S2, so that the electromagnetic valve body 76 is inadvertently separated from the valve seat 78 when not controlled by the control device 32. I am trying not to.

  The canister side bypass passage 66 is provided with a back pressure chamber pressure sensor 84 at a portion between the back pressure chamber 58 and the electromagnetic valve 68. The back pressure chamber pressure sensor 84 detects the pressure (internal pressure) PV in the back pressure chamber 58 and sends the information to the control device 32. The control device 32 can calculate a pressure difference ΔP (ΔP = PT−PV) between the tank internal pressure PT and the pressure PV of the back pressure chamber 58.

  When the solenoid valve 68 is opened, the back pressure chamber 58 is opened to the atmosphere, and a pressure difference ΔP is generated between the main chamber 52 (the tank internal pressure of the fuel tank 14 acts as a positive pressure) and the back pressure chamber 58. . In the fuel tank system 12 of the present embodiment, the opening / closing of the diaphragm valve 46 can be controlled according to the valve opening time of the electromagnetic valve 68. For example, as shown in FIG. 8, when the opening time of the electromagnetic valve 68 is up to a predetermined time T1, the pressure difference ΔP does not reach the opening pressure P3 of the diaphragm valve 46, so that the diaphragm valve 46 is not opened. On the other hand, when the valve opening time of the electromagnetic valve 68 exceeds the predetermined time T1, the pressure difference ΔP exceeds the valve opening pressure P3, so that the diaphragm valve 46 is opened.

  The fuel tank system 12 has a notification device 98. The notification device 98 displays predetermined information in accordance with a signal from the control device 32 and notifies the occupant, the refueling worker, and the like. This notification includes visual (display or lamp display) and auditory (audio).

  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. 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 during fuel supply, the control device 32 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, in the present embodiment, the tank-side bypass flow path 62 is provided with the reduced diameter portion 64, and a predetermined resistance is generated in the movement of gas between the main chamber 52 and the back pressure chamber 58. Takes a longer time than the back pressure chamber 58 to reach 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.

  Here, in order to open the diaphragm valve 46 with a small valve opening pressure, it is conceivable to downsize the valve member main body 54. However, since the valve member main body 54 is a member that closes the valve seat 50, when the valve member main body 54 is downsized, it is necessary to reduce the inner diameter of the valve seat 50, that is, a part of the canister side vent pipe 36C. . Therefore, it is desirable to increase the diameter of the valve seat 50 from the viewpoint of securing the flow rate of the vent pipe 36 when the diaphragm valve 46 is opened. Along with this, the valve member main body 54 also becomes large, but even the valve member main body 54 thus enlarged can be opened with a small valve opening pressure.

  In the present embodiment, the valve member main body 54 of the diaphragm valve 46 can be enlarged as described above, whereas the electromagnetic valve main body 76 of the electromagnetic valve 68 needs to exhibit an action of opening and closing the vent pipe 36 (the valve seat 50). Since it is sufficient that the canister side bypass passage 66 can be opened and closed, the size can be reduced. 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.

  In particular, in this embodiment, the valve opening direction of the solenoid valve body 76 of the solenoid valve 68 coincides with the direction in which positive pressure acts on the solenoid valve body 76 from the back pressure chamber 58 (as indicated by the arrow S2 in FIG. 2). Opposite direction). For this reason, the driving force from the coil part 72 for moving the solenoid valve main body 76 in the valve opening direction can be reduced, and power saving can be further measured.

  In the present embodiment, as described above, even if the inner diameter of the valve seat 50 is increased, the valve opening pressure of the diaphragm valve 46, that is, the force required for the operation of the valve member main body 54 can be reduced. By increasing the inner diameter of the valve seat 50, that is, the vent pipe 36, the ventilation resistance of the vent pipe 36 can be reduced. As a result, the evaporated fuel generated in the fuel tank 14 during refueling easily flows to the canister 34 through the vent pipe 36, and the fuel tank system 12 that facilitates refueling is obtained.

  Further, 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.

  While the vehicle is running, the tank internal pressure PT of the fuel tank 14 is detected by the tank internal pressure sensor 30 as shown in FIG. When the tank internal pressure PT does not exceed a predetermined value set in advance, the control device 32 closes the electromagnetic valve 68 as shown in FIG. 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 PT exceeds a predetermined value, the control device 32 controls opening / closing of the electromagnetic valve 68. When the solenoid valve 68 is opened (the same state as shown in FIG. 3), the tank side vent pipe 36T, the tank side bypass passage 62, the back pressure chamber 58, the canister side bypass passage 66, the canister side vent pipe 36C. Then, the evaporated fuel can move to the canister 34.

  By appropriately controlling the opening and closing of the electromagnetic valve 68, the flow rate of the evaporated fuel flowing through the vent pipe 36 and the tank internal pressure PT can be controlled. In this case, the opening / closing control of the electromagnetic valve 68 may be performed by adjusting the movement amount of the electromagnetic valve body 76 in the arrow S2 direction or in the opposite direction to adjust the cross-sectional area of the flow path. Moreover, you may perform by duty control (control of the time which switches the valve-opening position and valve-closing position of the valve member main body 54).

  The evaporated fuel discharged from the fuel tank 14 through the vent pipe 36 in this way may be adsorbed by the adsorbent of the canister 34. However, when the engine 26 is driven, it further passes through the purge pipe 38. It may be sent to the engine 26 and burned by the engine 26.

  Moreover, in the fuel tank system 12 of the present embodiment, the member for adjusting the flow rate in the vent pipe 36 when the tank internal pressure PT exceeds a predetermined value is used to open the back pressure chamber 58 to the atmosphere during refueling. The electromagnetic valve 68 is also used. Therefore, compared with the structure which provided the member which show | plays these effect | actions separately, while being able to comprise at low cost, it becomes lightweight.

  Even while the vehicle is parked, the electromagnetic valve 68 and the diaphragm valve 46 are normally closed, so that 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 PT of the fuel tank 14 becomes a positive pressure (a state higher than the atmospheric pressure) while the vehicle is parked, the tank internal pressure PT opens the electromagnetic valve body 76 of the electromagnetic valve 68 through the back pressure chamber 58. Acting in the direction (the direction opposite to the arrow S2 shown in FIG. 2). During parking, the electromagnetic valve 68 is not controlled to be opened and closed by the control device 32. However, when the tank internal pressure PT exceeds a predetermined threshold (hereinafter referred to as “positive pressure threshold”), the electromagnetic valve body 76 that has received the tank internal pressure PT (positive pressure) resists the spring force of the compression coil spring 80. Then, the valve moves in the valve opening direction and is in the same state as that shown in FIG. That is, the solenoid valve 68 operates as a positive pressure release valve that releases the positive pressure of the fuel tank 14, and it is not necessary to newly provide the positive pressure release valve. Therefore, compared with the structure which provided the positive pressure release valve separately, while being able to comprise at low cost, it becomes lightweight.

  Moreover, the solenoid valve 68 in the fuel tank system 12 of the present embodiment is controlled to open and close under predetermined conditions even during refueling and traveling as described above. In other words, the electromagnetic valve main body 76 moves between the valve opening position and the valve closing position even when the tank internal pressure PT exceeds the positive pressure threshold. For this reason, compared with a positive pressure release valve that is opened only when the tank internal pressure PT exceeds the positive pressure threshold, a phenomenon in which the electromagnetic valve body 76 is inadvertently fixed to the valve seat 78 is less likely to occur. Fixing resistance is improved.

  When the tank internal pressure PT of the fuel tank 14 becomes negative (a state lower than atmospheric pressure) while the vehicle is parked, the tank internal pressure PT (negative pressure) passes through the back pressure chamber 58 and is a valve member of the diaphragm valve 46. It acts in the direction of opening the main body 54 (the direction opposite to the arrow S1 shown in FIG. 2). When the tank internal pressure PT becomes lower than a predetermined threshold (hereinafter referred to as “negative pressure threshold”), as shown in FIG. 5, the valve member that receives the tank internal pressure PT (negative pressure) from the back pressure chamber 58 side. The main body 54 moves in the valve opening direction against the spring force of the compression coil spring 60 and the diaphragm 56. That is, the diaphragm valve 46 operates as a negative pressure release valve that releases the negative pressure of the fuel tank 14, and it is not necessary to newly provide the negative pressure release valve. Therefore, compared with the structure which provided the negative pressure release valve separately, while being able to comprise at low cost, it becomes lightweight.

  Moreover, as described above, the diaphragm valve 46 in the fuel tank system 12 of the present embodiment is opened and closed under a predetermined condition even during refueling. In other words, the valve member main body 54 moves between the valve opening position and the valve closing position even when the tank internal pressure PT falls below the negative pressure threshold. For this reason, compared with a negative pressure release valve that is opened only when the tank internal pressure PT falls below the negative pressure threshold, a phenomenon in which the valve member main body 54 is inadvertently fixed to the valve seat 50 is less likely to occur. Fixing resistance is improved.

  Further, in the fuel tank system 12 of the present embodiment, it is possible to detect the perforation of the fuel tank 14 (strictly, the fuel tank system) by the control device 32 according to the flow shown in FIG.

  In other words, when performing perforation detection, first, in step S102, the control device 32 drives the diagnostic pump 42.

  Next, in step S104, the control device 32 determines whether or not the tank internal pressure PT of the fuel tank 14 exceeds a predetermined specified positive pressure P1 (positive pressure threshold). That is, when the electromagnetic valve 68 is opened for a time equal to or longer than the time T1 shown in FIG. 8, the diaphragm valve 46 is opened. Therefore, when the tank internal pressure PT exceeds a predetermined specified positive pressure P1, There is a possibility that a large amount of gas containing the evaporated fuel in the fuel tank 14 flows into the canister 34 in a short time. Therefore, when the tank internal pressure PT exceeds the specified positive pressure P1, the control device 32 repeats the opening / closing control of the electromagnetic valve 68 at a predetermined time interval in step S106. ), And the pressure difference ΔP does not exceed the valve opening pressure P3 of the diaphragm valve 46. When the solenoid valve 68 is controlled to open and close in this manner, the gas in the fuel tank 14 gradually moves to the canister 34, and the tank internal pressure PT decreases with time as shown by the thick line L1 in FIG. However, the diaphragm valve 46 is not opened as shown in FIG. 6, and the closed state is maintained.

  On the other hand, when it is determined in step S104 that the tank internal pressure PT is equal to or lower than the predetermined specified positive pressure P1, the control device 32 proceeds to step S108 and switches the electromagnetic valve 68 (not on / off control). Open the valve. When the valve opening time of the electromagnetic valve 68 exceeds the predetermined time T1 shown in FIG. 8, the pressure difference ΔP between the main chamber 52 and the back pressure chamber 58 exceeds the valve opening pressure P3 of the diaphragm valve 46. As shown, the diaphragm valve 46 is opened, and a large amount of gas in the fuel tank 14 moves to the canister 34 in a short time. That is, as shown by the thick line L2 in FIG. 9, the tank internal pressure PT decreases with time.

  Here, as can be seen from FIG. 9, the thick line L2 is steeper than the thick line L1 (the amount of pressure drop per unit time is larger), and the solenoid valve 68 is controlled to open and close. In comparison, when the electromagnetic valve 68 is opened, the pressure in the fuel tank 14 decreases earlier. However, since the tank internal pressure PT is lower than the specified positive pressure P1, a phenomenon (so-called “blow-off”) that is not adsorbed by the adsorbent in the canister 34 and is released to the atmosphere is suppressed.

  Note that whether the solenoid valve 68 is opened or closed in step S106 or whether the solenoid valve 68 is opened in step S108, the fuel tank 14 is opened as indicated by the thick lines L1 and L2 in FIG. The tank internal pressure PT decreases. However, the tank internal pressure PT decreases in this way when the solenoid valve 68 operates normally. When the solenoid valve 68 is not opened due to an abnormality of the solenoid valve 68 (including opening for a predetermined time in the opening / closing control). As shown by a two-dot chain line L3 in FIG. 9, the tank internal pressure PT of the fuel tank 14 does not decrease.

  Therefore, in step S110, the control device 32 determines whether or not the tank internal pressure PT has decreased due to the driving of the diagnostic pump 42. When it is determined that the tank internal pressure PT has decreased (the solenoid valve 68 is not abnormal), in step S112, the control device 32 determines whether or not the tank internal pressure PT has decreased below the specified negative pressure P2. to decide. The specified negative pressure P2 is a threshold value that enables perforation detection to the fuel tank system when the tank internal pressure PT is equal to or lower than the specified negative pressure P2. The specified negative pressure P2 is lower than the atmospheric pressure P0 (the fuel tank 14 has a negative pressure).

  If it is determined that the tank internal pressure PT is not less than or equal to the specified negative pressure P2, the process returns to step S104 (the diagnostic pump 42 is continuously driven).

  If it is determined that the tank internal pressure PT is equal to or less than the specified negative pressure P2, the control device 32 performs perforation detection in step S114. In this perforated detection, it is determined whether or not the tank internal pressure PT is lower than the perforated determination pressure P5 based on the time when the specific tank internal pressure PT reaches the reference pressure P4.

  That is, when there is no perforation in the fuel tank system, as indicated by thick lines L4 and L6 in FIG. 9, the tank internal pressure PT continues to decrease and is lower than the perforation determination pressure P5 (perforation determination threshold). Become. On the other hand, when the fuel tank system is perforated, as indicated by alternate long and short dash lines L5 and L7 in FIG. 9, the tank internal pressure PT is reduced, but it is lower than the perforated determination pressure P5. It is thought that it should not be. In step S114, the control device 32 thus determines whether or not the fuel tank system is perforated. If no perforation has occurred, in step S116, the notifying device 98 notifies “no perforation” and the perforation. If this occurs, in step S118, “there is a hole” is notified. Finally, in step S120, the driving of the diagnostic pump 42 is stopped.

  When it is determined in step S112 that the tank internal pressure PT has not decreased, the process proceeds to step S122, and the notification device 98 notifies the abnormality of the electromagnetic valve 68. In step S120, the driving of the diagnostic pump 42 is stopped.

  As can be seen from the above description, in the fuel tank system 12 of the present embodiment, when the negative pressure is introduced into the fuel tank 14 in the detection of perforation of the fuel tank system, the tank internal pressure PT is equal to or higher than a predetermined specified positive pressure P1. In this case, the solenoid valve 68 is controlled to open and close, and the diaphragm valve 46 is not opened, so that a large amount of gas (including vaporized fuel) is prevented from moving from the fuel tank 14 to the canister 34 in a short time. ing. Therefore, it is possible to suppress a phenomenon (so-called “blow-off”) in which the evaporated fuel is not adsorbed by the adsorbent in the canister 34 and is released to the atmosphere.

  When the tank internal pressure PT does not exceed the predetermined positive pressure P1, the diaphragm valve 46 is also opened by opening the electromagnetic valve 68. For this reason, compared with the case where the tank internal pressure PT is the specified positive pressure P1, the negative pressure can be introduced into the fuel tank 14 in a short time, and the load on the diagnostic pump 42 is reduced. As a result, the power consumption of the diagnostic pump 42 is reduced, and the life of the negative pressure pump can be extended.

  Further, in the fuel tank system 12 of the present embodiment, when the diagnostic pump 42 is driven, it is determined whether or not the tank internal pressure PT has decreased, thereby determining the failure of the electromagnetic valve 68. The reliability as the fuel tank system 12 is also increased.

  In the above description, the method of driving the diagnostic pump 42 at the time of detecting the perforation is described. For example, even when the diagnostic pump 42 is not driven at the initial stage of detecting the perforation, the solenoid valve 68 is opened. Alternatively, by opening / closing control, the back pressure chamber 58 is opened to the atmosphere, and the pressure PV decreases. In order to actually detect perforation, it is necessary to drive the diagnostic pump 42 in order to introduce negative pressure into the fuel tank system. However, it is not possible to drive the diagnostic pump 42 from the beginning of perforation detection. Not required. For example, the determination in step S104 in the flow shown in FIG. 10, the electromagnetic valve opening / closing control in step S106, and the electromagnetic valve opening in step S108 are performed before the diagnostic pump 42 is driven (not the tank of the fuel tank 14). It is also possible to carry out with the internal pressure PT being positive.

  In the above description, the solenoid valve body 76 of the solenoid valve 68 has a valve opening direction that coincides with the direction in which positive pressure acts from the back pressure chamber 58. However, the valve opening direction of the electromagnetic valve main body 76 is not limited to this, and the valve opening direction of the electromagnetic valve main body 76 is the direction in which positive pressure is applied from the back pressure chamber 58, as shown in FIG. It may be the opposite. In this configuration, the driving force from the coil portion 72 for maintaining the solenoid valve main body 76 in the valve closing position can be small.

  Moreover, you may apply the structure of the solenoid valve 68 shown as a 2nd modification in FIG. In this configuration, a communication hole 96 that penetrates the valve member main body 54 in the thickness direction and allows the back pressure chamber 58 and the canister side vent pipe 36 </ b> C to communicate with each other is formed in the center of the valve member main body 54. The solenoid valve 68 is arranged so that the solenoid valve body 76 opens and closes the communication hole 96 on the back pressure chamber 58 side of the valve member body 54.

  In the second modification, a positive pressure release valve 86 is provided in the canister-side bypass pipe 36C that communicates the back pressure chamber 58 and the canister-side vent pipe 36C. The positive pressure release valve 86 is provided with an annular valve seat 88 in which the inner diameter of the canister-side bypass passage 66 is locally reduced. The positive pressure release valve main body 92 is positively pressurized by a compression coil spring 94. It is urged in a direction (arrow S2 direction) for closing the opening hole 90. When positive pressure equal to or greater than a predetermined positive pressure threshold acts from the back pressure chamber 58 side, the positive pressure release hole 90 is opened against the spring force of the compression coil spring 94.

  In the above example, the diameter-reduced portion 64 is provided in the tank-side bypass passage 62 to increase the flow resistance of the tank-side bypass passage 62 so that the differential pressure can be reliably maintained between the main chamber 52 and the back pressure chamber 58. ing. However, even if the flow path resistance of the tank-side bypass passage 62 is not increased, when the electromagnetic valve 68 is opened to bring the back pressure chamber 58 close to atmospheric pressure, the back pressure chamber 58 and the main chamber 52 It is possible to create a pressure difference between them. When the tank side bypass passage 62 is provided with a differential pressure maintaining means such as the reduced diameter portion 64, a pressure difference occurs between the back pressure chamber 58 and the main chamber 52 (the pressure in the back pressure chamber 58 is the pressure in the main chamber 52). Can be maintained more reliably. When the above-described reduced diameter portion 64 is used, it is possible to easily adjust the flow path resistance by appropriately setting the inner diameter and length of the reduced diameter portion 64 with a simple structure.

  As the valve member of the present invention, the diaphragm valve 46 is mentioned above, but the valve member is not limited to the diaphragm valve 46. For example, the configuration may be such that the diaphragm 56 is eliminated and the valve member main body 54 is increased in diameter so that the outer periphery thereof is in contact with the inner periphery of the valve housing 48. In this configuration, the valve member main body 54 alone separates the main chamber 52 and the back pressure chamber 58, and the vent pipe 36 is closed by contacting the valve seat 50, and the vent is separated from the valve seat 50. The position where the pipe 36 is opened is moved.

DESCRIPTION OF SYMBOLS 12 Fuel tank system 14 Fuel tank 26 Engine 30 Tank internal pressure sensor 32 Control apparatus 34 Canister 36 Vent piping 40 Atmospheric open piping (atmospheric open flow path)
42 Diagnosis pump (negative pressure pump)
46 Diaphragm valve (valve member)
52 Main chamber 54 Valve member body 58 Back pressure chamber 62 Tank-side bypass passage 66 Canister-side bypass passage (atmosphere release passage)
68 Solenoid valve

Claims (3)

A fuel tank capable of containing fuel, and
A canister that adsorbs and desorbs evaporated fuel generated in the fuel tank with an adsorbent;
An air release pipe for opening the inside of the canister to the atmosphere;
A vent pipe for communicating the fuel tank and the canister to send the evaporated fuel in the fuel tank to the canister;
The vent pipe is divided into a main chamber provided so that a tank internal pressure of the fuel tank acts, and a back pressure chamber on the opposite side of the main chamber with the valve member body interposed therebetween, with respect to the pressure of the back pressure chamber A valve member that opens when the pressure in the main chamber increases and the valve member body moves to allow the vent pipe to communicate;
A tank-side bypass passage for guiding the tank internal pressure of the fuel tank to the back pressure chamber;
An air release channel for opening the back pressure chamber to the atmosphere via the canister;
A solenoid valve capable of opening and closing the air release channel;
A negative pressure pump capable of acting a negative pressure in the fuel tank from the atmosphere opening pipe side than the valve member through the vent pipe;
A tank internal pressure sensor for detecting a tank internal pressure of the fuel tank;
A back pressure chamber pressure sensor for detecting the pressure of the back pressure chamber;
A control device for controlling the driving of the negative pressure pump and for controlling the opening and closing of the solenoid valve based on the tank internal pressure detected by the tank internal pressure sensor for detecting perforation of the fuel tank;
I have a,
While the control device is driving the negative pressure pump for perforation detection,
When the tank internal pressure exceeds a preset positive pressure threshold, the pressure difference between the tank internal pressure and the internal pressure of the back pressure chamber is controlled by opening and closing the solenoid valve. So that the pressure in the main chamber does not become so high that the valve member opens, with respect to the pressure in the back pressure chamber.
When the tank internal pressure is less than or equal to a preset positive pressure threshold, the solenoid valve is left open.
Fuel tank system. When the negative pressure is introduced into the fuel tank by driving the negative pressure pump and the tank internal pressure falls below a preset perforation determination threshold value, the control device indicates that the fuel tank is not perforated. The fuel tank system according to claim 1 for determination. 3. The fuel tank system according to claim 1 , wherein when the negative pressure pump is driven and the tank internal pressure does not decrease, the control device determines that the electromagnetic valve has failed.

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