JP2013155635A - Fuel tank system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel tank system, in which a solenoid valve can be size-reduced, and a fuel tank can be erliably maintained in a sealed state.SOLUTION: A diaphragm valve 46 is arranged in a vent pipe 36 for communicating a fuel tank 14 with a canister 34. A solenoid valve 68 is arranged in a canister side bypass passage 66 between a back pressure chamber 58 of the diaphragm valve 46 and a canister side vent pipe 36C. A communicating hole of the diaphragm valve 46 can be opened and closed from the side of the canister side vent pipe 36C by a one-way valve 86.

Description

  The present invention relates to a fuel tank system.

  In a fuel tank system that adsorbs and desorbs gas containing evaporated fuel in the fuel tank with the adsorbent of the canister, it is desired to appropriately adjust the flow rate of the gas to the canister.

  For example, Patent Document 1 describes a structure in which an evaporative fuel outflow suppression device is arranged in the middle of an evaporation line that guides fuel vapor inside a fuel tank to a canister. The shutoff valve of the evaporated fuel discharge suppression device is normally closed and is opened according to the pressure difference between the signal line and the canister side.

  However, in the structure described in Patent Document 1, the shutoff valve is opened when the pressure inside the fuel tank is positive and when the pressure is negative, so the fuel tank cannot be sealed.

JP 2000-192868 A

  In view of the above facts, an object of the present invention is to obtain a fuel tank system that can reduce the size of the solenoid valve and can reliably maintain the fuel tank in a sealed state.

  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, a control device for controlling opening and closing of the solenoid valve, and formed in the valve member main body, and positioned closer to the canister than the back pressure chamber A communication hole that allows communication between the canister side vent pipe and the back pressure chamber; and the communication hole is closed from the canister side vent pipe side so that a pressure difference between the back pressure chamber and the canister side vent pipe is reduced. And an on-off valve that opens the communication hole by the pressure difference when the pressure exceeds a preset positive pressure opening pressure.

  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 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. Further, the valve opening pressure of the valve member is reduced.

  The tank internal pressure (positive pressure) of the fuel tank acts on the back pressure chamber. The communication hole formed in the valve member body is normally closed from the side of the canister side vent pipe by an open / close valve, but the positive pressure release with a preset pressure difference between the back pressure chamber and the canister side vent pipe When the pressure exceeds the pressure, the communication hole is opened by the opening / closing valve due to this pressure difference, so that the positive pressure in the back pressure chamber, that is, the tank internal pressure, can be released to the canister side vent pipe (positive pressure release). Since the tank internal pressure is not released by opening the solenoid valve, the valve opening pressure of the solenoid valve does not need to be set low considering the positive pressure release. For this reason, it is possible to prevent the back pressure chamber from being inadvertently opened to the atmosphere, and the state where the fuel tank is sealed can be more reliably maintained.

  According to a second aspect of the present invention, in the first aspect of the present invention, in the state where the solenoid valve is not controlled by the control device, the tank internal pressure of the fuel tank is not more than a preset positive pressure threshold value. The valve opening pressure is such that the on-off valve is closed.

  That is, when the solenoid valve is not controlled (during non-control) and the tank internal pressure of the fuel tank is below the positive pressure threshold, the open / close valve can be kept closed, and the gas in the fuel tank can be inadvertently removed. Can be suppressed. Even when the electromagnetic valve is not controlled (during non-control), the on-off valve is opened when the tank internal pressure of the fuel tank exceeds the positive pressure threshold, so that the tank internal pressure of the fuel tank can be released. .

  In particular, when the solenoid valve is not controlled, the tank internal pressure is not released by opening the solenoid valve. Therefore, it is not necessary to set the valve opening pressure of the solenoid valve low considering the positive pressure release.

  According to a third aspect of the invention, in the first or second aspect of the invention, the fuel tank has a fuel supply state sensor that detects a fuel supply state to the fuel tank, and the fuel supply state sensor detects the fuel supply state. The control device controls the electromagnetic valve so as to open the air release channel.

  When the fuel supply state to the fuel tank is detected by the fuel supply state sensor, the control device controls the electromagnetic valve to open the atmosphere open flow path. Since the back pressure chamber is opened to the atmosphere, the pressure in the back pressure chamber is lower than the pressure in the main chamber, and the valve member opens the vent pipe. That is, when fuel is supplied to the fuel tank, the gas in the fuel tank can be sent to the canister through the vent pipe.

  According to a fourth aspect of the present invention, there is provided a valve member pressing spring for pressing the valve member main body from the back pressure chamber side to the closed position in the first aspect of the present invention. And an on-off valve body that can contact the valve member main body from the canister side vent piping side to close the communication hole, and a one-way valve that presses the on-off valve body against the valve member main body. A pressing spring.

  The valve member body is pressed from the back pressure chamber side by the valve member pressing spring, and is pressed from the canister side vent piping side by the one-way valve pressing spring via the on-off valve body, that is, springs from both sides. Therefore, the behavior of the valve member main body is stabilized.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, in the state where the valve member main body is at least moved to the valve open position, the open / close valve main body is separated from the valve member main body. The moving range is set.

  When the valve member main body is moved to the most open position, the open / close valve main body is separated from the valve member main body. It can suppress adhering to a member main body.

  Since the present invention has the above-described configuration, the fuel that can control the amount of gas flowing from the fuel tank to the canister can be obtained in which the solenoid valve can be downsized and the fuel tank system can be reliably maintained in a sealed state. A tank system is obtained.

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 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 and the solenoid valve opened in the fuel tank system of 1st Embodiment of this invention, and the one-way valve spaced apart from the diaphragm valve. It is sectional drawing which expands partially and shows a state in which the diaphragm valve and the solenoid valve are closed and the one-way valve is separated from the diaphragm valve in the fuel tank system of the first embodiment of the present invention. It is a graph which shows qualitatively the relation between the amount of movement of a diaphragm valve, and a spring load in the fuel tank system of a 1st embodiment of the present invention. 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 comparative example.

  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 20S, and the information is 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 (the direction of the arrow S1) to the valve member main body 54, and is an example of a valve member pressing spring. 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 solenoid valve coil spring 80 is attached to the plunger portion 74. The electromagnetic valve coil spring 80 applies a predetermined spring force to the electromagnetic valve main body 76 in the direction of the arrow S2, so that the electromagnetic valve main body 76 is carelessly removed from the valve seat 78 in a state where it is not controlled by the control device 32. I try not to leave.

  A communication hole 84 that penetrates the valve member main body 54 in the thickness direction is formed in the center of the valve member main body 54. The hole diameter of the communication hole 84 is made smaller than the inner diameter of the canister side vent pipe 36C (portion constituting the valve seat 50). The communication hole 84 allows the gas to communicate between the back pressure chamber 58 and the canister side vent pipe 36C.

  A one-way valve 86, which is an example of the on-off valve of the present invention, is provided in the canister side vent pipe 36C. The one-way valve 86 is a disc-shaped one-way valve main body 88 having a diameter larger than that of the communication hole 84 and urges the one-way valve main body 88 toward the valve member main body 54 (upward in FIG. 2). A compression coil spring 90. A mandrel 92 disposed inside the compression coil spring 90 is extended from the one-way valve main body 86 to suppress the deviation of the one-way valve main body 86. The compression coil spring 90 is an example of a one-way valve pressing spring.

  In the following, for the sake of convenience, the valve member main body 54 in FIG. 2 and the like will be described with the valve opening direction as the upper side and the valve closing direction as the lower side. However, the movement direction of the valve member main body 54 is not limited to this.

  In the normal state, the spring force of the compression coil spring 90 presses the one-way valve main body 88 toward the valve member main body 54 from the canister side vent pipe 36C side, but the valve closing state of the diaphragm valve 46 is maintained. It is said to be about. As shown in FIGS. 3 and 4, the one-way valve 86 opens the communication hole 84 when the valve is open.

  On the other hand, as shown in FIG. 2, the one-way valve 86 closes the communication hole 84 when the valve is closed. In this state, the valve member main body 54 receives a downward load from the compression coil spring 60 and an upward load from the compression coil spring 90. When the pressure difference in the back pressure chamber 58 is larger than the pressure in the canister side vent pipe 36C and the pressure difference becomes larger than a predetermined positive pressure release pressure, the one-way valve body 88 is The spring characteristics of the compression coil springs 60 and 90 are determined so as to be separated from the valve member main body 54 and to be opened.

  The movement amount (upward movement stroke) of the one-way valve main body 88 is set to be shorter than the movement amount of the valve member main body 54. That is, as shown in FIG. 3, the one-way valve main body 88 is in contact with the valve member main body 54 until the valve member main body 54 moves from the valve-closed state to the valve-opened state. The valve main body 88 does not move, and the valve member main body 54 is separated from the one-way valve main body 88 as shown in FIG.

  FIG. 6 qualitatively shows the load (spring load) that the valve member body 54 receives from the compression coil springs 60 and 90 in relation to the upward movement amount of the valve member body 54. In this graph, the dotted line L1 indicates the load of the compression coil spring 90, and the alternate long and short dash line L2 indicates the load from the compression coil spring 60. Therefore, the combined load (synthetic force) of these two compression coil springs 60 and 90 is indicated by a solid line L3. Further, as shown in FIG. 7, the two-dot chain line L4 is provided with only the compression coil spring 100 in the back pressure chamber 58, and provided with the communication hole 84 and the one-way valve 86 (compression coil spring 90). The load on the compression coil spring 100 is shown when it is not. In this embodiment and the comparative example, a downward load is actually applied to the valve member main body 54 from the diaphragm 56, and the one-dot chain line L2 and the two-dot chain line L4 in the graph of FIG. The load is also included for convenience.

  In the comparative example, the characteristic of the compression coil spring 60 is such that the diaphragm valve 46 is maintained in the closed state only by the compression coil spring 60 and is opened with a predetermined differential pressure between the main chamber 52 and the back pressure chamber 58. (Spring constant) has been determined. In the graph of FIG. 6, the spring load is set to be zero when the amount of movement of the valve member main body 54 is zero (actually, a slight downward spring load acts on the valve due to disturbance. It is also possible to adopt a structure that can suppress inadvertent vertical movement of the member main body 54).

  In contrast, in the present embodiment, as described above, the one-way valve main body 88 is in contact with the valve member main body 54 until the valve member main body 54 moves from the closed state to the open state (middle moving amount SM). Therefore, the downward load from the compression coil spring 60 and the upward load from the compression coil spring 90 are received. However, as the amount of movement of the valve member body 54 increases, the downward load from the compression coil spring 60 increases and the upward load from the compression coil spring 60 decreases. After the one-way valve main body 88 is separated from the valve member main body 54 (from the midway movement amount SM to the maximum movement amount FM), only the downward load from the compression coil spring 60 is received. Also in this case, the downward load from the compression coil spring 60 increases as the amount of movement of the valve member body 54 increases.

  In the present embodiment, as indicated by the movement amount range M1 in the graph, a part of the downward load of the compression coil spring 60 is offset by the upward load of the compression coil spring 90. Even if the spring constant of the spring 60 is increased, the resultant force of the compression coil springs 60 and 90 can ensure a magnitude of a force substantially equal to that of the comparative example.

  Then, when the compression coil spring 90 is separated from the one-way valve main body 88 (range of movement amount M2), the upward load from the compression coil spring 90 is not applied, and compared with the compression coil spring 100 of the comparative example. Therefore, the compression coil spring 60 having a large spring constant applies a larger downward load to the valve member main body 54.

  In order to set the movement amount of the one-way valve main body 88 in this way, for example, the compression coil spring 90 has a natural length at a position where the valve member main body 54 is separated from the one-way valve main body 88. The total length of the compression coil spring 90 may be set so that the movement of the one-way valve main body 88 is limited by a stopper or the like in a state where the one-way valve main body 88 has moved to a predetermined length.

  Further, the example shown in the graph of FIG. 6 illustrates a configuration in which the upward load from the compression coil spring 90 does not act on the valve member main body 54 when the total movement amount of the valve member main body 54 is less than half. However, it is sufficient that the valve member main body 54 has a structure in which the upward load from the compression coil spring 90 does not act on the valve member main body 54 in a state where the valve member main body 54 moves to the uppermost position (in the valve opening position direction).

  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. 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. Thereby, the diaphragm valve 46 is closed, and the fuel tank 14 contains the evaporated fuel inside.

The gas is sealed so that the gas does not move to the canister 34. In particular, in the present embodiment, an upward load of the compression coil spring 90 and a downward load of the compression coil spring 60 and the diaphragm 56 are acting on the valve member main body 54, and the diaphragm valve 46 maintains the closed state by the resultant force. It is not opened carelessly.

  In addition, in this embodiment, not only the downward load from the compression coil spring 60 but also the upward load from the compression coil spring 90 is acting on the valve member main body 54, so that the valve opening pressure is maintained at a predetermined value. Is easy and the valve characteristics are stable.

  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, the tank-side bypass passage 62 is provided with a reduced diameter portion 64, and it takes a longer time than the back pressure chamber 58 for the main chamber 52 to have the same pressure as the back pressure chamber 58. That is, the pressure difference is generated between the back pressure chamber 58 and the main chamber 52 (the pressure in the back pressure chamber 58 is lower than that in the main chamber 52). Therefore, the diaphragm valve 46 can be opened with a smaller valve opening pressure as compared with a configuration in which such a pressure difference does not occur between the back pressure chamber 58 and the main chamber 52. Thereby, as shown in FIG. 4, the valve member main body 54 moves to the back pressure chamber 58 side (upper side), and the diaphragm valve 46 is opened.

  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.

  When the diaphragm valve 46 is opened in this manner, the one-way valve body 88 is not moved until the valve member body 54 is moved upward (in the direction away from the valve seat 50) as shown in FIG. It contacts the valve member main body 54. That is, the valve member body moves while being sandwiched between the compression coil springs 60 and 90 from both front and rear sides (up and down) in the movement direction, so that the posture of the valve member body 54 is stabilized.

  In addition, in the present embodiment, since the communication hole 84 is formed at the center of the valve member main body 54, the one-way valve main body 88 that opens and closes the communication hole 84 also contacts at the central portion of the valve member main body 54. For this reason, the posture of the valve member main body 54 is more stable as compared with the configuration in which the one-way valve main body 88 is in contact with the peripheral portion of the valve member main body 54.

  During the upward movement of the valve member main body 54, the one-way valve main body 88 is separated from the valve member main body 54 and is not in contact with the valve member main body 54. Therefore, the valve member main body 54 has a spring force of the compression coil spring 90 ( The upward load) does not work.

  Thus, since the one-way valve main body 88 is separated from the valve member main body 54 (becomes non-contact), the one-way valve main body 88 is difficult to adhere to the valve member main body 54, and the diaphragm valve 46 and the one-way valve 86 Reliability is improved.

  When the lid 20 is closed due to the end of refueling to the fuel tank 14, the control device 32 closes the electromagnetic valve 68. As a result, the tank internal pressure (positive pressure) of the fuel tank 14 acts on both the main chamber 52 and the back pressure chamber 58. The pressure receiving area of the diaphragm valve 46 is wider on the back pressure chamber side than on the main chamber side. Further, a downward load (load in the valve closing direction) is applied to the valve member main body 54 from the compression coil spring 60. For this reason, the valve member main body 54 moves downward, and the diaphragm valve 46 is closed.

  In particular, in this embodiment, as can be seen from the graph of FIG. 6, the compression coil spring 60 having a large spring constant is used as compared with the structure of the comparative example, and the valve is changed from the open state to the closed state. In the initial stage of movement of the member main body 54 (in the range of the movement amount M2 until the one-way valve main body 88 comes into contact), only the downward load of the compression coil spring 60 acts on the valve member main body 54. That is, since a larger downward load acts on the valve member main body 54 than the structure of the comparative example, the responsiveness at the time of valve closing is high (the valve closes in a short time).

  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).

  Further, when the electromagnetic valve 68 is opened, the back pressure chamber 58 is opened to the atmosphere, so that the diaphragm valve 46 may be opened and closed due to a pressure difference between the back pressure chamber 58 and the main chamber 52 (see FIG. 4). The state indicated by the dotted line). Thus, by appropriately opening and closing not only the electromagnetic valve 68 but also the diaphragm valve 46, the pressure in the fuel tank 14 can be appropriately adjusted. In particular, between the valve member main body 54 and the valve seat 50 of the diaphragm valve 46 (between the main chamber 52 and the canister side vent pipe 36C), the opening cross-sectional area as a gas flow path is larger than that of the communication hole 84. Therefore, the amount of gas flowing through this large opening cross-sectional area can be adjusted appropriately.

  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.

  While the vehicle is parked, the electromagnetic valve 68 is not controlled by the control device 32. However, the electromagnetic valve 68 and the diaphragm valve 46 are closed by receiving the spring force of the compression coil spring 60 and the diaphragm 56 as shown in FIG. ing. The state where the fuel tank 14 is sealed is efficiently and reliably maintained, and the evaporated fuel generated in the fuel tank 14 does not move to the canister 34 carelessly.

  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 passes through the back pressure chamber 58 and the one-way valve body 88 of the one-way valve 86. Acts in the opening direction (downward). The electromagnetic valve 68 is not controlled to be opened or closed by the control device 32 during parking, but the one-way valve 86 is opened regardless of the opening / closing control of the electromagnetic valve 68, so that the positive pressure of the fuel tank 14 can be released.

  Thus, in this embodiment, the one-way valve 86 has a function as a valve (positive pressure release valve) for releasing the positive pressure of the fuel tank 14. The function as the positive pressure release valve can be assigned to the electromagnetic valve 68, but in this case, it is difficult to appropriately set the spring characteristics of the electromagnetic valve coil spring 80. On the other hand, in this embodiment, since the spring characteristic of the compression coil spring 90 can be set independently of the electromagnetic valve coil spring 80, the positive pressure of the fuel tank 14 can be reliably released.

  The electromagnetic valve coil spring 80 does not need to function as a positive pressure release valve. In other words, it is not necessary to weaken the spring force in consideration of positive pressure release. For this reason, even when a high positive pressure is applied from the back pressure chamber 58 side, the valve can be prevented from being opened carelessly. As a result, the back pressure chamber 58 can be prevented from being inadvertently released to the atmosphere, and the sealed state of the fuel tank 14 can be more reliably maintained.

  Note that the solenoid valve 68 in the fuel tank system 12 of the present embodiment is controlled to open and close under predetermined conditions during refueling and traveling as described above, and the solenoid valve main body 76 has a valve opening position and a valve closing position. Move between. For this reason, the phenomenon that the electromagnetic valve body 76 is inadvertently fixed to the valve seat 78 is difficult to occur, and the anti-sticking property 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.

  Similarly, as described above, the diaphragm valve 46 in the fuel tank system 12 according to the present embodiment is opened and closed under predetermined conditions 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 becomes negative and 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 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.

  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.

  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 short, the electromagnetic valve 68 only needs to be able to open and close the communication hole 84. For example, the electromagnetic valve 68 may be configured to include an electromagnetic valve main body that approaches or separates from the valve member main body 54 from the canister side vent pipe 36C side. In this configuration, when a positive pressure exceeding the positive pressure threshold value acts on the back pressure chamber 58 from within the fuel tank 14, the electromagnetic valve can be operated as a positive pressure release valve.

  When the electromagnetic valve 68 is provided on the back pressure chamber 58 side as in the above-described embodiment, there is an effect that the ventilation resistance of the canister side vent pipe 36C is smaller than the configuration provided on the canister side vent pipe 36C side. .

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 36 Vent pipe 36T Tank side vent pipe 36C Canister side vent pipe 40 Atmospheric release pipe 46 Diaphragm valve (valve member)
52 Main chamber 54 Valve member body 56 Diaphragm 58 Back pressure chamber 60 Compression coil spring (valve spring for valve member)
62 Tank side bypass passage 66 Canister side bypass passage 68 Solenoid valve 84 Communication hole 86 One-way valve 88 One-way valve body 90 Compression coil spring (pressing spring for one-way valve)

Claims (5)

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 control device for controlling opening and closing of the solenoid valve;
A communication hole that is formed in the valve member main body and that allows communication between the back pressure chamber and the canister side vent pipe located on the canister side with respect to the back pressure chamber;
The communication hole is closed from the side of the canister side vent pipe, and when the pressure difference between the back pressure chamber and the canister side vent pipe becomes larger than a preset positive pressure release pressure, the communication hole is opened by the pressure difference. An opening and closing valve,
Having fuel tank system.   2. The valve opening pressure at which the on-off valve is closed when the internal pressure of the fuel tank is equal to or lower than a preset positive pressure threshold when the electromagnetic valve is not controlled by the control device. The fuel tank system as described in. A fuel supply state sensor for detecting a fuel supply state to the fuel tank,
3. The fuel tank system according to claim 1, wherein when the fuel supply state is detected by the fuel supply state sensor, the control device controls the electromagnetic valve so as to open the atmosphere opening flow path. A valve member pressing spring that presses the valve member body from the back pressure chamber side to the valve closing position;
The on-off valve is
An on-off valve body capable of contacting the valve member body from the side of the canister side vent pipe and closing the communication hole;
A one-way valve pressing spring that presses the on-off valve body against the valve member body;
A fuel tank system according to any one of claims 1 to 3, further comprising:   The fuel tank system according to claim 4, wherein a moving range of the on-off valve main body is set such that the on-off valve main body is separated from the valve member main body at least in a state where the valve member main body is moved to the most open position.

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