JP2014058940A - Evaporated fuel processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve both improvement in oil supply property and improvement in sealing property in closing of a diaphragm valve.SOLUTION: An evaporated fuel processing device 30 includes a canister 32 capable of adsorbing and desorbing vapor produced in a fuel tank 10 of a vehicle; a vapor passage 34 communicating the fuel tank 10 and the canister 32 to each other; a diaphragm valve 42 opening and closing the vapor passage 34; a back pressure introduction passage 58 introducing tank internal pressure of the fuel tank 10 into a back pressure chamber 47 of the diaphragm valve 42; a relief passage 60 communicating the back pressure chamber 47 of the diaphragm valve 42 to the canister 32; a three-way valve 56 selectively opening and closing the back pressure introduction passage 58 and the relief passage 60; and an ECU 22 controlling passage switching of the three-way valve 56.

Description

  The present invention relates to a fuel vapor processing apparatus mounted mainly on a vehicle such as an automobile.

  This type of evaporated fuel processing apparatus includes a canister that can adsorb and desorb evaporated fuel generated in a fuel tank, a vapor passage that communicates the fuel tank and the canister, and a diaphragm valve that opens and closes the vapor passage ( (For example, refer to Patent Document 1).

JP-A-11-208293

According to the conventional evaporative fuel processing device, the diaphragm valve is opened by the tank internal pressure of the fuel tank, so it is difficult to achieve both improvement in oil supply and improvement in sealing performance when the diaphragm valve is closed. Met. That is, if the valve opening pressure of the diaphragm valve is lowered in order to improve the oil supply performance, the sealing performance when the diaphragm valve is closed is lowered. In this case, the tank internal pressure tends to leak to the canister. Conversely, if the valve opening pressure of the diaphragm valve is increased in order to improve the sealing performance when the diaphragm valve is closed, the pressure loss at the time of refueling, so-called pressure loss increases, and the refueling performance decreases.
The problem to be solved by the present invention is to achieve both the improvement of the oil supply performance and the improvement of the sealing performance when the diaphragm valve is closed.

The above problem can be solved by the present invention.
The first invention includes a canister that can adsorb and desorb vapor generated in a fuel tank of a vehicle, a vapor passage that communicates the fuel tank and the canister, a diaphragm valve that opens and closes the vapor passage, A back pressure introduction passage for introducing the tank internal pressure of the fuel tank into the back pressure chamber of the diaphragm valve, a relief passage communicating the back pressure chamber of the diaphragm valve with the canister, the back pressure introduction passage and the relief passage. Passage switching means for selectively opening and closing; and control means for controlling passage switching of the passage switching means. According to this configuration, when the passage switching means closes the back pressure introduction passage and opens the relief passage under the control of the control means, the back pressure chamber of the diaphragm valve is opened to the canister via the relief passage. Thereby, since the tank internal pressure does not act on the back pressure chamber of the diaphragm valve via the back pressure introduction passage, the valve opening pressure of the diaphragm valve becomes low. In this state, the diaphragm valve is quickly opened by the tank internal pressure of the fuel tank, so that the vapor in the fuel tank flows into the canister through the vapor passage and is adsorbed. Thereby, the pressure loss at the time of oil supply can be reduced, and oil supply property can be improved. Further, when the passage switching means opens the back pressure introduction passage and closes the relief passage under the control of the control means, the tank internal pressure acts on the back pressure chamber of the diaphragm valve via the back pressure introduction passage, so that the diaphragm valve The valve opening pressure increases. For this reason, the sealing performance when the diaphragm valve is closed can be improved. Therefore, it is possible to achieve both the improvement of the oil supply performance and the improvement of the sealing performance when the diaphragm valve is closed.

  According to a second invention, in the first invention, there is provided a lid state detection means for detecting an open state or an opening operation of the fuel lid of the vehicle, and the control means is an open state or an open state of the fuel lid by the lid state detection means. When an operation is detected, the passage switching means is controlled to close the back pressure introduction passage and open the relief passage. According to this configuration, when the open state or opening operation of the fuel lid is detected by the lid state detection means prior to refueling, the passage switching means closes the back pressure introduction passage and opens the relief passage by the control of the control means. The valve opening pressure of the diaphragm valve becomes low. For this reason, the diaphragm valve is opened at a low valve opening pressure due to the tank internal pressure higher than the valve opening pressure. Thereby, the tank internal pressure can be relieved to the canister via the vapor passage, and the tank internal pressure can be reduced (so-called pressure release). At the same time, the vapor in the fuel tank flows into the canister through the vapor passage and is adsorbed. As a result, the tank internal pressure is reduced to atmospheric pressure or substantially atmospheric pressure. Therefore, when the fuel cap is opened (when the fuel filler opening is opened), it is possible to prevent a vapor leakage so-called puffing phenomenon that vapor in the fuel tank is discharged from the fuel filler opening to the atmosphere. Further, at the time of refueling, the diaphragm valve is opened at a low valve opening pressure by the refueling pressure, so that the vapor in the fuel tank flows into the canister through the vapor passage and is adsorbed (recovered). Therefore, the so-called ORVR (Onboard Refueling Vapor Recovery) function can be exhibited. The lid state detection means may detect an open state (including a half-open state) of the fuel lid, or may detect an opening operation of the fuel lid. Further, the detection of the opening operation of the fuel lid corresponds to a lid switch for unlocking the electric lid opener, a switch or sensor for detecting the state of the opener lever of the manual lid opener, and the like.

  According to a third aspect of the present invention, in the first or second aspect of the invention, there is provided a full tank detection unit that detects a full tank state, and the control unit is configured to detect when the full tank state is detected by the full tank detection unit. The passage switching means is controlled to open the back pressure introduction passage and close the relief passage. According to this configuration, when a full tank state is detected by the full tank detecting means, the passage switching means opens the back pressure introduction passage and closes the relief passage under the control of the control means, so that the valve opening pressure of the diaphragm valve is increased. Therefore, the sealing performance when the diaphragm valve is closed is improved. As a result, the tank internal pressure does not leak to the canister and the fuel level in the inlet pipe does not decrease after the refueling operation of the fuel gun automatically stops as the tank is full. For this reason, even if the refueler pulls the lever of the refueling gun again, additional refueling cannot be performed. Therefore, supercharging can be prevented.

  In a fourth invention according to any one of the first to third inventions, the passage switching means is a three-way valve. According to this configuration, the back pressure introduction passage and the relief passage can be selectively opened and closed by the three-way valve as the passage switching means. Therefore, for example, the configuration can be simplified as compared with the case where two-way valves are individually arranged in the back pressure introduction passage and the relief passage.

  According to a fifth invention, in any one of the first to fourth inventions, a bypass passage that bypasses the pressure regulating chamber of the diaphragm valve is provided in the vapor passage, and a tank internal pressure of the fuel tank is provided in the bypass passage. A positive pressure valve that opens when the fuel pressure rises above a predetermined positive pressure and a negative pressure valve that opens when the tank internal pressure of the fuel tank drops below a predetermined negative pressure are provided in parallel. According to this configuration, when the valve opening pressure of the diaphragm valve is high, when the tank internal pressure rises above a predetermined pressure, the positive pressure valve is opened, so that the tank internal pressure is relieved to the canister side. Further, when the tank internal pressure falls below a predetermined negative pressure, the negative pressure valve is opened, and the air of the canister (including vapor) is introduced into the fuel tank. Thereby, deformation of the fuel tank can be prevented.

It is a block diagram which shows the evaporative fuel processing apparatus concerning Embodiment 1. FIG. It is sectional drawing which shows a diaphragm valve. It is explanatory drawing which shows the state of the three-way valve just before the start of oil supply. It is explanatory drawing which shows the state during refueling. It is explanatory drawing which shows the state at the time of a full tank. It is sectional drawing which shows the diaphragm valve concerning Embodiment 2. FIG. It is a block diagram which shows the evaporative fuel processing apparatus concerning Embodiment 3. It is a block diagram which shows the evaporative fuel processing apparatus concerning Embodiment 4.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

[Embodiment 1]
Embodiment 1 will be described. In this embodiment, the evaporative fuel processing apparatus mounted in vehicles, such as a motor vehicle, is illustrated. FIG. 1 is a configuration diagram showing an evaporative fuel processing apparatus. For convenience of explanation, the configuration relating to the fuel tank will be described, and then the evaporated fuel processing apparatus will be described.
As shown in FIG. 1, the fuel tank 10 of the vehicle has an inlet pipe 12. A fuel cap 14 is provided at the fuel filler opening 13 of the inlet pipe 12 so as to be openable and closable, that is, removable. One end portion (upper end portion) of the breather pipe 16 is connected in the vicinity of the fuel filler opening 13 of the inlet pipe 12. The other end portion (lower end portion) of the breather pipe 16 is opened to the gas layer portion of the fuel tank 10. At the time of refueling, smooth refueling is possible by returning the vapor in the fuel tank 10 to the inlet pipe 12 via the breather pipe 16. The other end of the breather pipe 16 is disposed at the same or substantially the same height as the fuel level Fa when the tank is full. Further, the fuel level other than when the tank is full is indicated by the symbol F. The fuel filler 13 is arranged in a fuel inlet box (not shown) provided in the vehicle body of the vehicle.

  A fuel lid 18 is provided in the fuel inlet box so as to be rotatable, that is, openable and closable via a hinge mechanism (not shown). The fuel inlet box is provided with an electric lid opener 20 as a lock mechanism for the fuel lid 18. The lid opener 20 unlocks the fuel lid 18 when a lid opening signal is output from an electronic control unit (hereinafter referred to as “ECU”) 22. The lid switch 24 as an operation switch for opening the fuel lid 18 outputs a signal for releasing the lock of the fuel lid 18 to the ECU 22. Further, the lid opener 20 unlocks the fuel lid 18 so that the fuel lid 18 can be opened (see the two-dot chain line 18 in FIG. 1). The refueling person can refuel by opening the fuel lid 18 and then opening the fuel cap 14. Moreover, the fuel lid 18 is locked in a closed state by the lid opener 20 by being closed by a manual operation by a fuel supplier. The lid switch 24 corresponds to “lid state detecting means” in this specification.

  The fuel tank 10 is provided with a tank internal pressure sensor 26. The tank internal pressure sensor 26 detects the tank internal pressure as a relative pressure with respect to the atmospheric pressure, and generates an output corresponding to the detected value. A tank internal pressure detection signal detected by the tank internal pressure sensor 26 is output to the ECU 22. The tank internal pressure sensor 26 corresponds to “tank internal pressure detecting means” in this specification.

  A fuel gauge 28 is provided in the fuel tank 10. The fuel gauge 28 is a float type liquid level position detection sensor and detects the amount of fuel in the fuel tank 10. A detection signal of the fuel amount (including a full tank) detected by the fuel gauge 28 is output to the ECU 22. The fuel gauge 28 corresponds to “full tank detecting means” in this specification.

  Next, an evaporative fuel processing device 30 that processes vapor (evaporated fuel) generated in the fuel tank 10 will be described. The fuel vapor processing apparatus 30 includes a canister 32 that can adsorb and desorb vapor. The canister 32 communicates with the fuel tank 10 (specifically, the air layer portion) via a vapor passage 34. The canister 32 is connected to an intake passage (not shown) of an internal combustion engine so-called engine via a purge passage 36. The canister 32 is opened to the atmosphere via the atmosphere port 38. A purge valve 40 is provided in the purge passage 36. The purge valve 40 is subjected to open / close control, so-called purge control, by the ECU 22. The canister 32 is filled with an adsorbent (not shown) such as activated carbon capable of adsorbing and desorbing vapor.

  The vapor generated in the fuel tank 10 flows into the canister 32 through the vapor passage 34 and is adsorbed by the canister 32 (specifically, an adsorbent). Further, when the purge valve 40 is opened by purge control by the ECU 22 during the operation of the engine, air (outside air) is supplied from the atmospheric port 38 to the canister 32 as the intake negative pressure of the engine is introduced into the canister 32. be introduced. Thereby, the vapor desorbed from the canister 32 (specifically, the adsorbent) is purged to the intake passage of the engine via the purge passage 36. A cut-off valve 41 that opens and closes by fuel buoyancy is provided at the inlet of the vapor passage 34 that opens into the fuel tank 10. The cut-off valve 41 is normally maintained in an open state, and prevents the fuel in the fuel tank 10 from flowing out into the vapor passage 34 by closing when the vehicle rolls over. The cut-off valve 41 is disposed at a position higher than the fuel level Fa when the tank is full.

The vapor passage 34 is divided into a tank side passage portion 34a and a canister side passage portion 34b. A diaphragm valve 42 is provided between the tank side passage portion 34a and the canister side passage portion 34b. FIG. 2 is a sectional view showing the diaphragm valve.
As shown in FIG. 2, the diaphragm valve 42 includes a valve case 44 and a diaphragm 45 provided in the valve case 44. The diaphragm 45 is made of a rubber-like elastic body and has flexibility. The inside of the valve case 44 is divided into two chambers, that is, a pressure regulating chamber 46 and a back pressure chamber 47 by the diaphragm 45. Two connection ports 44 a and 44 b are formed in the lower portion of the valve case 44. One connection port 44 a communicates with the inlet side of the pressure regulating chamber 46 and is connected to the tank side passage portion 34 a of the vapor passage 34. The other connection port 44 b communicates with the outlet side of the pressure regulating chamber 46 and is connected to the canister side passage portion 34 b of the vapor passage 34. Further, one back pressure introduction port 44 c communicating with the back pressure chamber 47 is formed in the upper part of the valve case 44. Note that both connection ports 44 a and 44 b of the diaphragm valve 42 communicating with the vapor passage 34 form a part of the vapor passage 34.

  A valve seat 50 is formed at the upstream opening end of the canister side passage 34b. A valve portion 52 that can be seated on and separated from the valve seat 50 is provided at the center of the diaphragm 45. In the back pressure chamber 47, a spring 54 made of, for example, a coil spring is interposed between the valve case 44 and the diaphragm 45. The spring 54 biases the valve portion 52 of the diaphragm 45 in the direction in which the valve portion 52 is seated on the valve seat 50, that is, in the valve closing direction. The diaphragm valve 42 opens when the pressure difference between the tank internal pressure of the fuel tank 10 and the canister 32 of the canister 32 exceeds a predetermined value (see a two-dot chain line 52 in FIG. 2), and the diaphragm valve 42 opens. The tank internal pressure can flow into the canister 32.

  As shown in FIG. 1, the first connection port of the three-way valve 56 is connected to the back pressure introduction port 44 c of the diaphragm valve 42. A back pressure introduction passage 58 is branched from the middle of the tank side passage portion 34a of the vapor passage 34. The back pressure introduction passage 58 is connected to the second connection port of the three-way valve 56. A relief passage 60 is connected to the third connection port of the three-way valve 56. The relief passage 60 is joined to the vapor passage 34 in the middle of the canister side passage portion 34b. The three-way valve 56 is an electromagnetic switching valve and is controlled to be switched by the ECU 22. The three-way valve 56 selectively opens and closes the back pressure introduction passage 58 and the relief passage 60 to the back pressure chamber 47 of the diaphragm valve 42 by opening and closing the back pressure introduction passage 58 and the relief passage 60. The three-way valve 56 corresponds to “passage switching means” in this specification. The ECU 22 corresponds to “control means” in this specification.

Next, the operation of the evaporated fuel processing device 30 will be described.
(1) During parking In principle, the diaphragm valve 42 is kept closed while the vehicle is parked. That is, under the control of the ECU 22, the three-way valve 56 opens the back pressure introduction passage 58 and closes the relief passage 60 (see FIG. 1). In this state, the tank internal pressure acts on the back pressure chamber 47 of the diaphragm valve 42 via the back pressure introduction passage 58, thereby increasing the valve opening pressure of the diaphragm valve 42. The valve opening pressure at this time is the total pressure of the urging force of the spring 54 and the tank internal pressure. For this reason, the diaphragm valve 42 is maintained in a closed state (blocked state) by a high valve opening pressure. Therefore, vapor does not flow out to the canister 32 unless the tank internal pressure exceeds the high valve opening pressure of the diaphragm valve 42. Thus, by maintaining the sealed state of the fuel tank 10, the generation of vapor in the fuel tank 10 can be suppressed. It is possible to relieve the tank internal pressure at the abnormal pressure to the canister 32 by setting the high valve opening pressure of the diaphragm valve 42 in accordance with the minimum value of the tank internal pressure at the abnormal pressure.

(2) Immediately before the start of refueling When the lid switch 24 is operated by a refueling person while the vehicle is stopped, the three-way valve 56 closes the back pressure introduction passage 58 and opens the relief passage 60 under the control of the ECU 22 ( (See FIG. 3). As a result, the tank internal pressure does not act on the back pressure chamber 47 of the diaphragm valve 42 via the back pressure introduction passage 58, so the valve opening pressure of the diaphragm valve 42 is lowered. The valve opening pressure at this time is only the pressure due to the urging force of the spring 54. For this reason, the diaphragm valve 42 is opened by the tank internal pressure higher than the valve opening pressure. Thereby, the tank internal pressure can be relieved to the canister 32 via the vapor passage 34, and the tank internal pressure can be reduced (so-called pressure release). At the same time, the vapor in the fuel tank 10 flows into the canister 32 via the vapor passage 34 and is adsorbed. As a result, the tank internal pressure is reduced to atmospheric pressure or substantially atmospheric pressure. The tank internal pressure introduced into the back pressure chamber 47 before the switching of the three-way valve 56 is relieved to the canister 32 through the relief passage 60 and the canister side passage portion 34 b of the vapor passage 34 by the switching of the three-way valve 56. The Thereby, the back pressure chamber 47 becomes atmospheric pressure or substantially atmospheric pressure.

  Further, the ECU 22 outputs a signal for unlocking the fuel lid 18 to the lid opener 20 when it is determined that the tank internal pressure has decreased to atmospheric pressure or substantially atmospheric pressure based on the detection signal from the tank internal pressure sensor 26. In response to the signal, the lid opener 20 unlocks the fuel lid 18. As a result, the fuel lid 18 can be opened after the tank internal pressure reaches a value close to atmospheric pressure. When the lock of the fuel lid 18 is released, the fuel lid 18 is opened (see the two-dot chain line 18 in FIG. 3). Subsequently, the fuel cap 14 is opened by the fuel supplier (see the two-dot chain line 14 in FIG. 3). At this time, the tank internal pressure has already been reduced (reduced pressure) to near atmospheric pressure. For this reason, even if the fuel cap 14 is opened, it is possible to prevent a vapor leak, that is, a so-called “pafloss” phenomenon that vapor is discharged from the fuel filler port 13 to the atmosphere.

  The ECU 22 outputs a signal for releasing the lock to the lid opener 20 based on a detection signal from the tank internal pressure sensor 26, and the tank internal pressure becomes atmospheric pressure or substantially atmospheric pressure after the lid switch 24 is operated. A signal for releasing the lock may be output to the lid opener 20 after the time required for the operation has elapsed. Further, the ECU 22 may output a signal for releasing the lock to the lid opener 20 by operating the lid switch 24. In this case, the fuel supplier may open the fuel cap 14 after the fuel lid 18 has been opened and after the time required for the tank internal pressure to become atmospheric pressure or substantially atmospheric pressure has elapsed.

(3) During refueling The ECU 22 opens the relief passage 60, that is, a diaphragm valve, from the start of refueling by the refueling gun 64 to the end of refueling (specifically, until the fuel lid 18 is closed). The valve opening pressure of 42 is kept low (see FIG. 4). In this state, the refueling person inserts the refueling gun 64 into the refueling port 13 and pulls the lever 65 of the refueling gun 64 to start refueling. When refueling is started, the diaphragm valve 42 is opened at a low valve opening pressure due to the refueling pressure. For this reason, the pressure loss at the time of refueling can be reduced and oil supply property can be improved. Further, the vapor in the fuel tank 10 can be adsorbed (recovered) to the canister 32 via the vapor passage 34. Thereby, an ORVR function (a function of collecting vapor during refueling) can be exhibited.
(4) When the tank is full When the ECU 22 determines that the fuel tank has reached the full tank based on the detection signal of the fuel level F in the fuel tank 10 from the fuel gauge 28 (the liquid level Fa when the tank is full), the control of the ECU 22 As a result, the three-way valve 56 opens the back pressure introduction passage 58 and closes the relief passage 60 (see FIG. 5). As a result, the vapor passage 34 is blocked while the valve opening pressure of the diaphragm valve 42 is high, as in the normal state. Along with this, the refueling operation is automatically stopped by the automatic stop function of the refueling gun 64. Further, when the vapor passage 34 is shut off while the opening pressure of the diaphragm valve 42 is high, the tank internal pressure does not leak to the canister 32 after the fuel gun 64 is automatically stopped, and the fuel in the inlet pipe 12 The liquid level does not drop. For this reason, even if the refueler pulls the lever 65 of the refueling gun 64 again, additional refueling cannot be performed. Therefore, supercharging can be prevented. Further, after refueling, the refueling person pulls out the refueling gun 64 from the refueling port 13, closes the refueling port 13 with the fuel cap 14, and then closes the fuel lid 18 to complete refueling.

(5) During operation of the engine During operation of the engine, in principle, the diaphragm valve 42 is maintained in a closed state (see FIG. 1), as in the case of parking. Purge control (purge valve 40 opening / closing control) for purging vapor adsorbed on the canister 32 is executed when a predetermined purge condition is satisfied during operation of the engine. As a result, the vapor in the canister 32 is discharged into the intake passage (not shown) of the engine together with the air sucked into the canister 32 from the atmospheric port 38 due to the negative intake air pressure of the engine, so-called purge. Further, during the purge, the internal pressure of the tank can be maintained at atmospheric pressure or substantially atmospheric pressure by appropriately closing the back pressure introduction passage 58 and opening the relief passage 60 by the three-way valve 56 under the control of the ECU 22.

  According to the evaporative fuel processing device 30, when the three-way valve 56 closes the back pressure introduction passage 58 and opens the relief passage 60 under the control of the ECU 22, the back pressure chamber 47 of the diaphragm valve 42 passes through the relief passage 60 and the canister 32. Open to the side (see FIG. 4). As a result, the tank internal pressure does not act on the back pressure chamber 47 of the diaphragm valve 42 via the back pressure introduction passage 58, so the valve opening pressure of the diaphragm valve 42 is lowered. In this state, the diaphragm valve 42 is quickly opened by the tank internal pressure of the fuel tank 10, so that the vapor in the fuel tank 10 flows into the canister 32 via the vapor passage 34 and is adsorbed. Thereby, the pressure loss at the time of oil supply can be reduced, and oil supply property can be improved. When the three-way valve 56 opens the back pressure introduction passage 58 and closes the relief passage 60 under the control of the ECU 22, the tank internal pressure acts on the back pressure chamber 47 of the diaphragm valve 42 via the back pressure introduction passage 58. The valve opening pressure of the diaphragm valve 42 is increased (see FIG. 1). For this reason, the sealing performance when the diaphragm valve 42 is closed can be improved. Therefore, it is possible to achieve both the improvement of the oil supply performance and the improvement of the sealing performance when the diaphragm valve 42 is closed.

  Prior to refueling, when the opening operation of the fuel lid 18 is detected by the lid switch 24, the three-way valve 56 closes the back pressure introduction passage 58 and opens the relief passage 60 under the control of the ECU 22, whereby the diaphragm valve 42 is opened. The valve opening pressure is lowered (see FIG. 3). For this reason, the diaphragm valve 42 is opened at a low valve opening pressure due to the tank internal pressure higher than the valve opening pressure. Thereby, the tank internal pressure can be relieved to the canister 32 via the vapor passage 34, and the tank internal pressure can be reduced (so-called pressure release). At the same time, the vapor in the fuel tank 10 flows into the canister 32 via the vapor passage 34 and is adsorbed. As a result, the tank internal pressure is reduced to atmospheric pressure or substantially atmospheric pressure. Therefore, when the fuel cap 14 is opened (when the fuel filler port 13 is opened), vapor leakage, that is, so-called puffing phenomenon, in which the vapor in the fuel tank 10 is discharged from the fuel filler port 13 to the atmosphere can be prevented. Further, at the time of refueling (see FIG. 4), the diaphragm valve 42 is opened at a low valve opening pressure by the refueling pressure, so that the vapor in the fuel tank 10 flows into the canister 32 through the vapor passage 34. Adsorbed (recovered). Therefore, the vapor recovery function at the time of refueling, the so-called ORVR function can be exhibited.

  When the fuel gauge 28 detects a full state, the three-way valve 56 opens the back pressure introduction passage 58 and closes the relief passage 60 under the control of the ECU 22, thereby increasing the valve opening pressure of the diaphragm valve 42 ( (See FIG. 5). For this reason, the sealing performance when the diaphragm valve 42 is closed is improved. Thereby, after the refueling operation of the refueling gun 64 is automatically stopped as the tank is full, the tank internal pressure does not leak to the canister 32, and the fuel level in the inlet pipe 12 does not decrease. For this reason, even if the refueler pulls the lever 65 of the refueling gun 64 again, additional refueling cannot be performed. Therefore, supercharging can be prevented.

  Further, the back pressure introduction passage 58 and the relief passage 60 can be selectively opened and closed by the three-way valve 56 as passage switching means. Therefore, for example, the configuration can be simplified as compared with the case where two-way valves are individually arranged in the back pressure introduction passage 58 and the relief passage 60.

[Embodiment 2]
A second embodiment will be described. Since the subsequent embodiments are modifications to the first embodiment, the changed portions will be described, and redundant descriptions will be omitted. FIG. 6 is a sectional view showing the diaphragm valve.
In the present embodiment, as shown in FIG. 6, a bypass passage 70 that bypasses the pressure regulating chamber 46 is formed in the valve case 44 of the diaphragm valve 42 in the first embodiment. A positive pressure side port 71 and a negative pressure side port 72 are formed in the bypass passage 70 in parallel. A positive pressure valve 74 is incorporated in the positive pressure side port 71. The positive pressure valve 74 is urged in the valve closing direction by a spring 75. The positive pressure valve 74 is a check valve that is normally closed and opened when the tank internal pressure exceeds a predetermined value. A negative pressure valve 76 is incorporated in the negative pressure side port 72. The negative pressure valve 76 is urged in the valve closing direction by a spring 77. The negative pressure valve 76 is a check valve that is normally closed and opened when the tank internal pressure becomes a predetermined value or less.

  According to this embodiment, when the valve opening pressure of the diaphragm valve 42 is high (for example, during parking), when the tank internal pressure rises above a predetermined pressure, the positive pressure valve 74 is opened, so that the tank internal pressure is reduced. Relief to the canister 32 side. Note that the valve opening pressure of the positive pressure valve 74 is lower than the high valve opening pressure of the diaphragm valve 42. Further, when the tank internal pressure falls below a predetermined negative pressure, the negative pressure valve 76 is opened so that the air (including vapor) of the canister 32 is introduced into the fuel tank 10. Thereby, deformation of the fuel tank 10 can be prevented. Further, the tank internal pressure can be maintained within a predetermined pressure range by the set pressures of the positive pressure valve 74 and the negative pressure valve 76. In the present embodiment, the diaphragm valve 42 in which the positive pressure valve 74 and the negative pressure valve 76 are modularized is illustrated, but each may be provided independently, or a plurality of them may be modularized. Further, the positive pressure valve 74 or the negative pressure valve 76 may be omitted.

[Embodiment 3]
A third embodiment will be described. This embodiment is a modification of the first embodiment. FIG. 7 is a block diagram showing the fuel vapor processing apparatus.
In this embodiment, as shown in FIG. 7, instead of the three-way valve 56 in the first embodiment, a first two-way valve 80 is provided in the back pressure introduction passage 58 and a second two-way is provided in the relief passage 60. A valve 82 is provided. Both the two-way valves 80 and 82 are electromagnetic on-off valves, and are opened and closed by the ECU 22 in a reciprocal manner. Therefore, according to this embodiment, the back pressure introduction passage 58 and the relief passage 60 can be reciprocally opened and closed. The two two-way valves 80 and 82 constitute “passage switching means” in the present specification.

[Embodiment 4]
A fourth embodiment will be described. This embodiment is a modification of the first embodiment. FIG. 8 is a cross-sectional view showing the evaporated fuel processing apparatus.
In this embodiment, as shown in FIG. 8, the lid switch 24 and the lid opener 20 in the first embodiment (see FIG. 1) are omitted, and a lid opening / closing sensor 90 for detecting the open state of the fuel lid 18 is provided. is there. A detection signal of the lid opening / closing sensor 90 is output to the ECU 22. Further, the ECU 22 determines the open / close state of the fuel lid 18 based on a detection signal from the lid open / close sensor 90. In this case, the fuel supplier may open the fuel cap 14 after the fuel lid 18 has been opened and after the time required for the tank internal pressure to become atmospheric pressure or substantially atmospheric pressure has elapsed. The lid opening / closing sensor 90 corresponds to “lid state detecting means” in this specification.

  The present invention is not limited to the above-described embodiment, and modifications can be made without departing from the gist of the present invention.

10 ... Fuel tank 22 ... ECU (control means)
24. Lid switch (lid state detecting means)
26 ... Tank internal pressure sensor (tank internal pressure detecting means)
28 ... Fuel gauge (full tank detection means)
32 ... Canister 34 ... Vapor passage 42 ... Diaphragm valve 46 ... Pressure regulating chamber 47 ... Back pressure chamber 56 ... Three-way valve (passage switching means)
58 ... Back pressure introduction passage 60 ... Relief passage 30 ... Evaporative fuel processing device 70 ... Bypass passage 74 ... Positive pressure valve 76 ... Negative pressure valve 80, 82 ... Two-way valve (passage switching means)
90 ... Lid opening / closing sensor (lid state detecting means)

Claims (5)

A canister capable of adsorbing and desorbing vapor generated in a fuel tank of a vehicle;
A vapor passage communicating the fuel tank and the canister;
A diaphragm valve for opening and closing the vapor passage;
A back pressure introduction passage for introducing a tank internal pressure of the fuel tank into a back pressure chamber of the diaphragm valve;
A relief passage communicating the back pressure chamber of the diaphragm valve with the canister;
Passage switching means for selectively opening and closing the back pressure introduction passage and the relief passage;
And a control means for controlling the passage switching of the passage switching means. It is an evaporative fuel processing apparatus of Claim 1, Comprising:
A lid state detecting means for detecting an open state or an opening operation of the fuel lid of the vehicle;
The control means controls the passage switching means to close the back pressure introduction passage and open the relief passage when the open state or opening operation of the fuel lid is detected by the lid state detection means. An evaporative fuel processing apparatus. The evaporative fuel processing apparatus according to claim 1 or 2,
A full tank detecting means for detecting a full tank condition;
The control means controls the passage switching means to open the back pressure introduction passage and close the relief passage when the full-tank state is detected by the full-tank detection means. Fuel processor. It is an evaporative fuel processing apparatus as described in any one of Claims 1-3,
The fuel vapor processing apparatus, wherein the passage switching means is a three-way valve. It is an evaporative fuel processing apparatus as described in any one of Claims 1-4, Comprising:
A bypass passage is provided in the vapor passage to bypass the pressure regulating chamber of the diaphragm valve,
In the bypass passage, a positive pressure valve that opens when the tank internal pressure of the fuel tank rises above a predetermined positive pressure and a negative pressure valve that opens when the tank internal pressure of the fuel tank drops below a predetermined negative pressure are arranged in parallel. The evaporative fuel processing apparatus characterized by providing.

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