JP2013167177A - Fuel tank system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly control a flow rate of gas flowing from a fuel tank into a canister while the tank inner pressure of the fuel tank is high.SOLUTION: A diaphragm valve 46 is provided at a vent pipe 36 for making the fuel tank 14 communicate with a canister 34. A canister-side bypass passage 66 is provided between a back pressure chamber 58 of the diaphragm valve 46 and a canister-side vent pipe 36C. A second bypass passage 66 is provided with a solenoid valve 68. The opening/closing control of the solenoid valve 66 is performed based on tank inner pressure detected by a tank inner pressure sensor 30.

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, it is necessary to open the blocking valve when the gas in the fuel tank is released to the canister or the like when the tank internal pressure of the fuel tank becomes high, except during refueling. However, if the blocking valve is opened while the tank internal pressure is high, a gas containing a large amount of evaporated fuel moves to the canister.

JP 2005-104394 A

  In view of the above facts, an object of the present invention is to obtain a fuel tank system capable of appropriately controlling the flow rate of gas flowing from the fuel tank to the canister in a state where the tank internal pressure of the fuel tank is high.

  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 from the fuel tank to the valve member in the vent pipe, and a tank side bypass passage capable of communicating with the back pressure chamber; The canister side bypass pipe that can communicate with the back pressure chamber and the canister side vent pipe from the valve member to the canister in the front pipe, and the canister side bypass path is controlled to open and close. An electromagnetic valve that is operated, a tank internal pressure sensor that detects a tank internal pressure of the fuel tank, and the electromagnetic pressure according to the tank internal pressure when the tank internal pressure detected by the tank internal pressure sensor is higher than a predetermined first threshold value. And a control device that opens the valve by adjusting the opening of the valve.

  In this fuel tank system, the fuel tank and the canister can communicate with each other through a vent pipe. The vent pipe is provided with a bypass path from the tank side bypass passage through the back pressure chamber to the canister 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 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 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 the tank internal pressure is higher than the predetermined first threshold value, the control device opens the electromagnetic valve. Thereby, the gas in the fuel tank flows to the canister via the tank side vent pipe, the tank side bypass pipe, the back pressure chamber, the canister side bypass pipe, and the canister side vent pipe. When opening the electromagnetic valve, the control device adjusts the opening of the electromagnetic valve in accordance with the tank internal pressure. By adjusting the opening degree in this way, it is possible to appropriately adjust the amount of gas flowing from the fuel tank to the canister.

  The adjustment of the “opening” here is, for example, by duty control of the solenoid valve or adjustment of the flow path cross-sectional area of the canister side bypass passage by adjusting the movement amount of the solenoid valve body in the valve opening direction. It can be carried out. These can be used alone or in appropriate combination.

  According to a second aspect of the present invention, in the first aspect of the present invention, when the control device does not satisfy the second threshold when the tank internal pressure is equal to or higher than a second threshold higher than the first threshold. The opening is made smaller.

  When the tank internal pressure is equal to or higher than the second threshold value (in the case of high pressure), the opening degree of the solenoid valve is smaller than in the case where the tank pressure is less than the second threshold value (in the case of low pressure). A large amount of flow can be suppressed in a short time.

  According to a third aspect of the present invention, in the second aspect of the present invention, the opening of the solenoid valve when the tank internal pressure is equal to or greater than the second threshold is a differential pressure between the main chamber and the back pressure chamber. Is set to an opening degree at which the back pressure chamber communicates with the canister so as to be equal to or lower than the valve opening pressure of the valve member.

  When the tank internal pressure is greater than or equal to the second threshold value, the back pressure chamber communicates with the canister by opening the solenoid valve. However, the opening of the solenoid valve is determined by the pressure difference between the main chamber and the back pressure chamber. The opening is set as follows. Since the valve member is not opened, the gas in the fuel tank flows through the tank side vent pipe, tank side bypass pipe, back pressure chamber, canister side bypass pipe, and canister side vent pipe without passing through the valve member. . Thus, by not opening the valve member, it is possible to suppress a large amount of high-pressure gas in the fuel tank from flowing in the canister in a short time.

  According to a fourth aspect of the present invention, in the second aspect of the present invention, the degree of opening of the electromagnetic valve when the tank internal pressure is less than the second threshold is a difference between the main chamber and the back pressure chamber. The opening is set so that the back pressure chamber communicates with the canister so that the pressure is equal to or higher than the valve opening pressure of the valve member.

  When the tank internal pressure is less than the second threshold value, the back pressure chamber communicates with the canister by opening the solenoid valve. However, the opening of the solenoid valve is determined by the differential pressure between the main chamber and the back pressure chamber. The opening is set to be higher than the pressure. Since the valve member is opened, the fuel tank gas flows to the canister via the tank side vent piping, tank side bypass piping, back pressure chamber, canister side bypass piping, and canister side vent piping, as well as tank side vent piping. Then, it flows to the canister through the valve member and the canister side vent pipe. Thus, by opening the valve member, a large amount of high-pressure gas in the fuel tank can be moved to the canister in a short time, and the tank internal pressure can be reduced in a short time.

  Since the present invention is configured as described above, the flow rate of the gas flowing from the fuel tank to the canister can be appropriately controlled with the tank internal pressure of the fuel tank being 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 a flowchart which shows the opening / closing control of the solenoid valve in the fuel tank system of 1st Embodiment of this invention. It is a graph which shows the time change of the pressure of the main chamber and the back pressure chamber in the fuel tank system of a 1st embodiment of the present invention, (A) shows the 1st opening-and-closing control, and (B) shows the 2nd opening-and-closing control, respectively. . FIG. 3 is a partially enlarged cross-sectional view of the fuel tank system according to the first embodiment of the present invention in a state where the tank internal pressure is equal to or higher than a first threshold and the solenoid valve is controlled to be opened and closed. In the fuel tank system of 1st Embodiment of this invention, a tank internal pressure is more than a 1st threshold value, It is sectional drawing shown partially expanded in the state which opened the solenoid valve and the diaphragm valve. 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. It is sectional drawing which expands partially and shows the state which the diaphragm valve and the solenoid valve closed in the fuel tank system of the 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 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 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 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 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.

  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 opens the opening portion of the valve seat 50. 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 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.

  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 of the fuel tank 14 is detected by the tank internal pressure sensor 30 as shown in FIG. Then, in accordance with the flow shown in FIG. 5, control (so-called “pressure release”) for suppressing an excessive increase in the tank internal pressure is performed by opening / closing control of the electromagnetic valve 68 based on the tank internal pressure. In the present embodiment, the opening / closing control of the electromagnetic valve 68 is performed by duty control (control of the time for switching the valve opening position and the valve closing position of the valve member main body 54). The cross-sectional area of the flow path may be adjusted by adjusting the amount of movement in the direction of arrow S2 or in the opposite direction, or by moving (shifting) the solenoid valve main body 76 in the direction orthogonal to the arrow S2. . The “opening” of the solenoid valve 68 is adjusted by combining these alone or appropriately.

  First, in step S102, it is determined whether or not the tank internal pressure is equal to or higher than a preset first threshold value. The first threshold is a threshold set to prevent an excessive increase in tank internal pressure. If it is determined that the tank internal pressure does not exceed the first threshold value, it is not necessary to depressurize the fuel tank 14, so this control ends.

  On the other hand, if it is determined that the tank internal pressure is equal to or higher than the first threshold, it is determined in step S104 whether the tank internal pressure is equal to or higher than the second threshold. The second threshold value is higher than the first threshold value. When the electromagnetic valve 68 is opened in a state where the tank internal pressure is equal to or higher than the second threshold value, the differential pressure between the main chamber 52 and the back pressure chamber 58 is the diaphragm valve 46. This is the pressure value that may exceed the valve opening pressure. Since the tank internal pressure is high, the gas containing the evaporated fuel in the fuel tank 14 opens the diaphragm valve 46, thereby causing the tank side vent pipe 36 </ b> T, the diaphragm valve 46, and the canister side vent pipe 36 </ b> C to pass through. Then, when a large amount flows into the canister 34 in a short time, there is a possibility that the adsorption capacity of the canister 34 may be exceeded.

  Therefore, if it is determined in step S104 that the tank internal pressure is equal to or greater than the second threshold value, the process proceeds to step S106, and the electromagnetic valve 68 is opened for a predetermined time T1 (this time T1 is shorter than time T2 described later). A first opening / closing control is performed in which the valve and the valve closing immediately thereafter are repeated.

  FIG. 6A shows changes over time in the pressures of the main chamber 52 (one-dot chain line L1) and the back pressure chamber 58 (two-dot chain line L2) in the first opening / closing control. By opening the electromagnetic valve 68, the pressure in the main chamber 52 and the back pressure chamber 58 decreases. In particular, the back pressure chamber 58 has a larger pressure drop per unit time than the main chamber 52. However, even if the electromagnetic valve 68 is opened for the time T1, the pressure difference between the main chamber 52 and the back pressure chamber 58 does not reach the valve opening pressure of the diaphragm valve 46. Since the diaphragm valve 46 is not opened and only the solenoid valve 68 is opened, the gas in the fuel tank 14 is supplied with the tank side vent pipe 36T and the tank side bypass as shown by an arrow F1 in FIG. It flows to the canister 34 through the pipe 62, the back pressure chamber 58, the canister side bypass pipe 66, and the canister side vent pipe 36C. Since the diaphragm valve 46 is not opened, a large amount of gas in the fuel tank 14 is prevented from flowing into the canister 34 in a short time.

  If the operation of opening the solenoid valve 68 for a predetermined time T1 and the operation of closing the solenoid valve 68 for a short time immediately after that are repeated a plurality of times, the pressure in the back pressure chamber 58 repeatedly decreases and increases. It gradually decreases at long time intervals.

  When the predetermined time T1 shown in FIG. 6A has elapsed (the electromagnetic valve 68 is repeatedly opened and closed several times during this period), the pressure in the main chamber 52 (substantially equal to the tank internal pressure) is below the first threshold value, In addition, the pressure difference between the main chamber 52 and the back pressure chamber 58 reaches the valve opening pressure of the diaphragm valve 46. As a result, the diaphragm valve 46 is opened. The gas in the fuel tank 14 passes through the diaphragm valve 46 from the tank side vent pipe 36T and the canister side vent pipe 36C as shown by the arrow F2 in FIG. 8 as well as the flow path indicated by the arrow F1. The canister 34 flows.

  That is, in a state where the tank internal pressure is lower than the second threshold, gas can be sent to the canister 34 by the two flow paths F1 and F2 from the fuel tank 14 to the canister 34, and the tank internal pressure can be reduced in a short time. Is possible. Further, it is possible to suppress a large amount of evaporated fuel from flowing into the engine 26, and the driving performance (drivability) of the automobile due to disturbance of the air fuel consumption is not reduced.

  On the other hand, if it is determined in step S104 that the tank internal pressure does not reach the second threshold value, the process proceeds to step S108, and the electromagnetic valve 68 is turned on for a predetermined time T2 (this time T2 is determined in the first opening / closing control). Second opening / closing control is performed to open the valve for a period longer than the valve opening time T1.

  FIG. 6B shows changes in pressure of the main chamber 52 and the back pressure chamber 58 over time in the second opening / closing control. By opening the electromagnetic valve 68 at time T2, the pressure in the back pressure chamber 58 decreases. In the example shown in FIG. 6B, when the electromagnetic valve 68 is opened only once, the pressure difference between the main chamber 52 and the back pressure chamber 58 is opened when the time T2 is reached. Reach pressure. The diaphragm valve 46 is opened. However, when the second opening / closing control is performed, it is assumed that the tank internal pressure has not reached the second threshold value, so that the evaporated fuel in the fuel tank 14 flows into the canister 34. Can be adsorbed by the canister 34. The time T2 may be set so short that the pressure difference between the main chamber 52 and the back pressure chamber 58 does not reach the valve opening pressure of the diaphragm valve 46 by opening the electromagnetic valve 68 only once. . In this case, when the electromagnetic valve 68 is opened for the second time (at least less than the first opening / closing control) at the time T2, the pressure difference between the main chamber 52 and the back pressure chamber 58 is reduced. The valve opening pressure may be reached.

  The gas can be sent to the canister 34 through the two flow paths F1 and F2 from the fuel tank 14 to the canister 34, and the tank internal pressure can be reduced in a short time.

  In the fuel tank system 12 of the present embodiment, the opening and closing of the diaphragm valve 46 is controlled at the time of so-called depressurization when the tank internal pressure exceeds the predetermined first threshold value (in some cases, the canister from the fuel tank 14 can be controlled). The electromagnetic valve 68 for opening the back pressure chamber 58 to the atmosphere at the time of refueling also serves as a member that adjusts the amount of gas flowing to 34. 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.

  During parking of the vehicle, in a normal state, the electromagnetic valve 68 and the diaphragm valve 46 are 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 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 passes through the back pressure chamber 58 and opens the electromagnetic valve body 76 of the electromagnetic valve 68. Acting in the direction opposite to the arrow S2 shown in FIG. 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 exceeds a predetermined threshold (hereinafter referred to as “positive pressure threshold”), the electromagnetic valve body 76 that has received the tank internal pressure (positive pressure) resists the spring force of the compression coil spring 80. It moves in the valve opening direction, and the state is similar to the state 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 exceeds the positive pressure threshold. For this reason, compared with a positive pressure release valve that is opened only when the tank internal pressure 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 property is improved.

  When the tank internal pressure of the fuel tank 14 becomes negative (a state lower than atmospheric pressure) while the vehicle is parked, the tank internal pressure (negative pressure) passes through the back pressure chamber 58 and the valve member main body 54 of the diaphragm valve 46. Acts in the direction to open the valve (the direction opposite to the arrow S1 shown in FIG. 2). When the tank internal pressure becomes lower than a predetermined threshold (hereinafter referred to as “negative pressure threshold”), as shown in FIG. 5, the valve member main body 54 receives the tank internal pressure (negative pressure) from the back pressure chamber 58 side. However, it 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 open position and the valve close position even when the tank internal pressure falls below the negative pressure threshold. For this reason, compared to a negative pressure release valve that is opened only when the tank internal pressure 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 property is improved.

  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 opposite to the direction of the positive pressure from the back pressure chamber 58 as shown in FIG. May be. 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.

  Although the diaphragm valve 46 is mentioned above as a valve member of the present invention, 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.

  In the above description, the first threshold value and the second threshold value are set in advance with respect to the tank internal pressure of the fuel tank 14, and the opening degree of the electromagnetic valve 68 is adjusted at the time of pressure release based on these threshold values. It is only necessary to adjust the flow rate of the gas flowing through the vent pipe 36 so that the gas containing the evaporated fuel in the fuel tank 14 does not flow to the canister 34 in a short time. For example, only the second threshold value may be set, and when the tank internal pressure becomes equal to or higher than the second threshold value, the opening degree of the electromagnetic valve 68 may be adjusted (the opening degree is reduced) to perform “pressure release”.

12 Fuel Tank System 14 Fuel Tank 20S Lid Open / Close Sensor (Oil Supply State Sensor)
30 Tank internal pressure sensor 32 Controller 34 Canister 36C Canister side vent piping 36T Tank side vent piping 40 Atmospheric release piping 46 Diaphragm valve 52 Main chamber 58 Back pressure chamber 62 Tank side bypass passage 66 Canister side bypass passage 68 Solenoid valve

Claims (4)

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 capable of communicating the tank side vent pipe and the back pressure chamber from the fuel tank to the valve member in the vent pipe;
A canister-side bypass passage capable of communicating the canister-side vent pipe and the back pressure chamber from the valve member to the canister in the vent pipe;
An electromagnetic valve provided in the canister side bypass passage and controlled to open and close the canister side bypass passage;
A tank internal pressure sensor for detecting a tank internal pressure of the fuel tank;
A control device that adjusts and opens the solenoid valve according to the tank internal pressure when the tank internal pressure detected by the tank internal pressure sensor is higher than a predetermined first threshold;
Having fuel tank system.   2. The fuel tank system according to claim 1, wherein when the tank internal pressure is equal to or higher than a second threshold value that is higher than the first threshold value, the control device makes the opening degree smaller than when the tank pressure is less than the second threshold value.   When the tank internal pressure is equal to or higher than the second threshold value, the back pressure chamber canister is adjusted so 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. The fuel tank system according to claim 2, wherein the fuel tank system is set to an opening degree that allows communication with the fuel tank.   When the tank internal pressure is less than the second threshold value, the opening of the solenoid valve is adjusted so that the differential pressure between the main chamber and the back pressure chamber is equal to or higher than the valve opening pressure of the valve member. The fuel tank system according to claim 2, wherein the fuel tank system is set to an opening degree that allows communication with the canister.