JP2006291793A - Evaporated fuel treating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To certainly prevent fuel vapor from being released to the atmosphere when determining leakage of an evaporated fuel passage. <P>SOLUTION: This device is provided with a fuel tank 10, a canister 12 connected to the fuel tank 10 and adsorbing evaporated fuel generated in the fuel tank 10, a negative pressure pump 38 connected to the canister 12 and introducing negative pressure to a closed space including the fuel tank 10 through the canister 12, a purge VSV 36 connected to the intake pipe 37 of an internal combustion engine and opened in a predetermined case, so that intake negative pressure of the internal combustion engine is introduced to the canister 12, and a scavenging means sending fuel vapor accumulated in the vicinity of the negative pressure pump 38 to the canister 12 by utilizing intake negative pressure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

    The present invention relates to an evaporated fuel processing apparatus, and is particularly suitable for application to an apparatus for processing evaporated fuel generated in a fuel tank.

  2. Description of the Related Art Conventionally, there is known an evaporative fuel processing apparatus that adsorbs evaporated fuel (fuel vapor) generated in a fuel tank to a canister, thereby preventing the fuel vapor from being released into the atmosphere.

  In such an evaporative fuel processing apparatus, a method of applying pressure to the evaporative fuel path in order to determine leakage in a closed space is known. For example, Japanese Patent Laid-Open No. 2003-42014 describes a method of introducing a negative pressure using a pump into an evaporative fuel path including a fuel tank and determining leakage in a closed space based on pressure information at that time. Yes.

Japanese Patent Laid-Open No. 2003-42014 JP 2004-156492 A JP-A-9-184454 JP 2003-155958 A

  However, in the above conventional technique, when a negative pressure is introduced by a pump when performing leakage determination, a flow from the closed space toward the pump is generated. For this reason, when the fuel vapor is floating in the vicinity of the pump in the closed circuit space, there arises a problem that the fuel vapor is discharged from the pump into the atmosphere.

  The present invention has been made to solve the above-described problems, and it is an object of the present invention to surely prevent the fuel vapor from being released into the atmosphere when performing the leakage determination of the evaporated fuel path. .

  In order to achieve the above object, a first invention is connected to a fuel tank, a canister that is connected to the fuel tank and absorbs evaporated fuel generated in the fuel tank, and is connected to the canister, via the canister. Intake negative pressure introduction that introduces intake negative pressure of the internal combustion engine into the canister by being connected to a pump that introduces negative pressure into the closed space including the fuel tank and an intake pipe of the internal combustion engine and opening in a predetermined case And a scavenging means for sending fuel vapor accumulated in the vicinity of the pump to the canister using the intake negative pressure.

  According to a second invention, in the first invention, a passage connecting the downstream side of the pump and the canister is provided, and the scavenging means operates the pump in a state where the intake negative pressure is introduced into the canister. Thus, the fuel vapor staying in the vicinity of the pump is sent to the canister via the passage.

  According to a third invention, in the first invention, a check valve is provided between the pump and the canister, and blocks a flow of air from the pump toward the canister. The check valve bypasses the check valve. A bypass flow path connecting the canister and the pump; and a shut-off valve provided in the bypass flow path, wherein the scavenging means is configured to shut off the pressure while the pressure due to the intake negative pressure is introduced into the canister. By opening the valve, fuel vapor staying in the vicinity of the pump is sent to the canister via the bypass flow path.

  In a fourth aspect based on the third aspect, the scavenging means closes the pump in a state where pressure due to the negative intake pressure remains in the canister after the intake negative pressure introduction valve is closed. The staying fuel vapor is sent to the canister via the bypass flow path.

  According to the first invention, the fuel vapor accumulated in the vicinity of the pump can be sent to the canister using the intake negative pressure, so that the fuel paper can be reliably discharged from the vicinity of the pump. Therefore, when a negative pressure is introduced into the closed space during the leak determination, it is possible to reliably prevent the fuel vapor from being released into the atmosphere.

  According to the second aspect of the invention, the fuel vapor staying in the vicinity of the pump can be sent to the passage on the downstream side of the pump by operating the pump with the intake negative pressure introduced into the canister. Since the downstream passage of the pump and the canister are connected, the fuel vapor sent to the downstream passage of the pump can be sent to the canister by the intake negative pressure introduced into the canister.

  According to the third aspect of the present invention, the intake negative pressure is introduced into the pump through the bypass flow path by opening the shut-off valve provided in the bypass flow path with the pressure due to the intake negative pressure introduced into the canister. Can do. Therefore, the fuel vapor staying in the vicinity of the pump can be sent to the canister via the bypass channel.

  According to the fourth invention, after the intake negative pressure introducing valve is closed, the fuel vapor staying in the vicinity of the pump is sent to the canister while the pressure due to the intake negative pressure remains in the canister. It is possible to prevent the negative pressure from becoming excessively high. Therefore, it is possible to surely prevent new fuel vapor from being generated from the fuel tank.

  Several embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted. The present invention is not limited to the following embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram for explaining the outline of the evaporated fuel processing apparatus according to each embodiment of the present invention. As shown in FIG. 1, the apparatus of this embodiment includes a fuel tank 10, a canister 12, a pump module 14, and an air filter 16.

  A canister 12 communicates with the fuel tank 10 through a vapor passage 18. A pump module 14 communicates with the canister 12 through a pump passage 20. The canister 12 is filled with activated carbon 22 for adsorbing fuel vapor flowing from the fuel tank 10. The canister 12 is provided with a vapor port 24 connected to the vapor passage 18, a pump side port 26 connected to the pump passage 20, and a purge port 32 communicating with a purge passage 30 described later. As shown in FIG. 1, the vapor port 24, the pump side port 26, and the purge port 32 are provided on the same side with respect to the activated carbon 22. Further, barriers 34 and 35 for restricting the flow of gas and fuel vapor in the activated carbon 22 are provided inside the canister 12.

  The purge passage 30 is a passage communicating with an intake pipe (not shown in FIG. 1) of the internal combustion engine. In the middle of the purge passage 30, a purge VSV 36 for controlling the conduction state is provided.

FIG. 2 is a schematic diagram showing the configuration of the pump module 14. The pump module 14 includes a negative pressure pump 38, a pressure sensor 40, a switching valve (VSV) 42, a switching actuator 44, a reference orifice 46, and a check valve 48. The switching valve 42 has a passage 42a and a passage 42b. The reference orifice 46 is a reference hole (for example, φ0.5 mm) provided for measuring a reference pressure P _REF used for leak determination. The check valve 48 has a function of blocking the gas flow from the negative pressure pump 38 toward the pressure sensor 40.

  The switching valve 42 is driven by energizing the switching actuator 44, and is set to one of the states shown in FIG. 2 (A) and FIG. 2 (B). Here, in the state (VSV-ON) shown in FIG. 2A, the negative pressure pump 38 and the pump-side port 26 of the canister 12 are connected by the passage 42a. In the state shown in FIG. 2B, the air filter 16 and the pump side port 26 are connected by the passage 42b, and a path from the air filter 16 to the negative pressure pump 38 through the reference orifice 46 is formed.

  As shown in FIG. 1, the evaporated fuel processing apparatus of this embodiment includes an ECU (Electronic Control Unit) 50. The ECU 50 is connected to a negative pressure pump 38, a pressure sensor 40, a switching actuator 44, and the like in the pump module 14.

  In the evaporative fuel processing apparatus of the present embodiment configured as described above, a method for determining evaporative fuel path leakage will be described below. In the present embodiment, a negative pressure is applied to the fuel vapor path including the fuel tank 10 and the canister 12 by the pump module 14, and leakage determination is performed based on the pressure detected by the pressure sensor 40. It is preferable to determine whether the fuel vapor path leaks when the internal combustion engine is stopped.

When performing leak determination, first, the reference pressure P _REF is measured. When measuring the reference pressure _PREF , the switching valve 42 is set to the position shown in FIG. 2B (VSV-OFF). When the negative pressure pump 38 is driven in the state shown in FIG. 2B, the air on the check valve 48 side is sucked by the negative pressure pump 38, and the flow of air in the direction indicated by the arrow in FIG. Arise. As a result, the upstream side of the reference orifice 46 provided with the pressure sensor 40 has a negative pressure. In this state, the pressure is measured by the pressure sensor 40 to detect the reference pressure P _REF corresponding to the φ 0.5 mm reference orifice 46. can do.

Next, in order to introduce a negative pressure into the evaporated fuel path including the fuel tank 10 and the canister 12, the purge VSV 36 is closed, and the switching valve 42 is set to the position shown in FIG. 2A (VSV-ON). When the negative pressure pump 38 is driven in this state, the air in the canister 12 is sucked by the negative pressure pump 38, and an air flow in the direction indicated by the arrow in FIG. As a result, a negative pressure is introduced into the evaporated fuel path including the fuel tank 10 and the canister 12. And the pressure P _{actual value} at this time is _measured with the pressure sensor 40.

FIG. 3 is a schematic diagram showing the relationship between the transition of the _{actual measurement value} of the pressure P detected by the pressure sensor 40 and the reference pressure P _REF when a negative pressure is introduced into the fuel vapor path including the fuel tank 10 and the canister 12. It is. As shown in FIG. 3, when the negative pressure pump 38 is operated to apply a negative pressure to the fuel vapor path including the fuel tank 10 and the canister 12, the _{actual measurement value} of the pressure P decreases and a certain time has passed. Then settle down to a steady state. The _{actual value} of the pressure P is compared with the reference pressure _PREF after having settled to a steady state. In FIG. 3, P _REF and P _{actually measured values} are both negative values.

As shown by a solid line in FIG. 3, when the _{actual measurement value} of the pressure P is higher than the reference pressure P _REF, a leak hole whose pressure in the evaporated fuel path is equivalent to φ0.5 mm even though a negative pressure is applied. It can be determined that the pressure is higher than the pressure in the case where the pressure is generated. Therefore, in this case, it can be determined that a leak hole larger than φ0.5 is formed in the evaporated fuel path.

On the other hand, as shown by the dashed line in FIG. 3, when the pressure P _{measured value} is lower than the reference pressure P _REF is lower than the pressure when the pressure in the fuel vapor passage occurs leaking hole of the corresponding φ0.5mm It can be judged that it is in a state. Therefore, in this case, it can be determined that the leak hole in the evaporated fuel path is smaller than φ0.5.

As described above, according to the evaporated fuel processing apparatus of the present embodiment, it is determined whether or not there is a leak hole in the evaporated fuel path based on the result of comparing the pressure P _{actual measurement value} with the reference pressure _PREF. Can do.

  FIG. 4 is a schematic diagram showing a state in which the fuel vapor adsorbed on the canister 12 is purged to the intake pipe 37 of the internal combustion engine. As shown in FIG. 4, when purging the fuel vapor, the switching valve 42 is set to the position shown in FIG. 2B (VSV-OFF), and the pump side port 26 goes to the atmosphere (air filter 16 side). Opened. In this state, when the purge VSV 36 is opened during operation of the internal combustion engine, the intake negative pressure in the intake pipe 37 is guided into the purge passage 30, and the intake negative pressure reaches the purge port 32 of the canister 12. As a result, an air flow from the air filter 16 toward the pump side port 26 and the purge port 32 is generated as indicated by an arrow in FIG. When such an air flow occurs, desorption occurs in the fuel vapor adsorbed on the activated carbon 22. Accordingly, by appropriately opening the purge VSV 36 during operation of the internal combustion engine, the fuel vapor adsorbed on the canister 12 can be appropriately purged by the internal combustion engine.

  In the system described above, when a negative pressure is introduced into the evaporated fuel path for leak determination, the gas in the evaporated fuel path including the fuel tank 10 is released from the air filter 16 to the atmosphere. At this time, if the fuel vapor is floating in the path through which the negative pressure is introduced, the fuel vapor may be released into the atmosphere. In particular, when the fuel vapor is floating in the pump module 14 and the pump passage 20, the fuel vapor may be released into the atmosphere by introducing a negative pressure. Further, when the adsorption state of the fuel vapor in the canister 12 is saturated, a part of the fuel vapor adsorbed by the introduction of the negative pressure may deviate, and the fuel vapor may be released into the atmosphere.

  Therefore, in the present embodiment, as described in FIG. 4, when purging the fuel vapor during the operation of the internal combustion engine, the negative pressure pump 38 is operated to float in or near the negative pressure pump 38. The fuel vapor is sent to the canister 12 side using the intake negative pressure to scavenge the pump module 14 and the vicinity thereof.

  FIG. 5 is a schematic diagram showing a state in which the inside of the pump module 14 and the vicinity thereof are scavenged using the intake negative pressure. As shown in FIG. 5, when scavenging using intake negative pressure, the switching valve 42 is set to the state shown in FIG. 2B (VSV-OFF) as in FIG. During operation, the purge VSV 36 is opened.

  As a result, similarly to the case of FIG. 4, the negative pressure of the intake pipe 37 is introduced into the pump module 14 via the canister 12. When scavenging in the pump module 14 is performed, the negative pressure pump 38 is operated in this state. As a result, an air flow from the reference orifice 46 to the negative pressure pump 38 through the check valve 48 is generated as indicated by an arrow in FIG. The air flowing into the negative pressure pump 38 is sent to the canister 14 side through the passage 42b of the switching valve (VSV) 42 by the negative pressure of the intake pipe 37.

  As a result, the fuel vapor floating in or near the negative pressure pump 38 or in the passage connecting the negative pressure pump 38 and the air filter 16 can be sent to the canister 14 side. The module can be scavenged. Therefore, it is possible to prevent the fuel vapor floating in the vicinity of the negative pressure pump 38 from being released into the atmosphere when a negative pressure is introduced into the evaporated fuel path at the time of leak detection.

  The fuel vapor sent to the canister 12 is adsorbed by the activated carbon 22 in the vicinity of the pump side port 26. As will be described later, by purging the fuel vapor to the intake pipe 37 before operating the negative pressure pump 38 for scavenging, the fuel vapor adsorbed on the activated carbon 22 in the vicinity of the pump-side port 26 can be removed. it can. Therefore, when scavenging is performed by operating the negative pressure pump 38, the fuel vapor sent to the canister 12 can be reliably adsorbed to the activated carbon 22 in the vicinity of the pump-side port 26. The fuel vapor adsorbed on the activated carbon 22 by scavenging is then purged to the intake pipe 37 by purging with the method of FIG.

  As will be described later, when the negative pressure of the intake pipe 37 is low and the absolute value of the intake negative pressure introduced into the pump module 14 exceeds a predetermined threshold value, the negative pressure necessary for scavenging is required. Since the drive amount of the pressure pump 38 increases, scavenging by the method shown in FIG. 5 is preferably performed when the absolute value of the intake negative pressure is not more than a predetermined threshold value.

  FIG. 6 is a schematic diagram showing the fuel vapor floating state and adsorption state around the canister 12. Here, FIG. 6A shows a state before the negative pressure is introduced into the evaporated fuel path. As shown in FIG. 6A, the fuel vapor generated in the fuel tank 10 is adsorbed by the activated carbon 22 of the canister 12. A part of the fuel vapor flows from the canister 12 toward the pump module 14 and floats in the pump module 14 or in the vicinity of the pump passage 20.

  FIG. 6B shows a state in which the inside of the pump module 14 is scavenged from the state shown in FIG. 6A by using the negative pressure of the intake pipe 37 by the method described in FIG. As shown in FIG. 6B, when the negative pressure of the intake pipe 37 is introduced into the pump module 14, an air flow from the pump module 14 side toward the canister 12 occurs, and the negative pressure pump 38 is operated in this state. Fuel vapor floating in the pump module 14 or in the vicinity of the pump passage 20 is adsorbed by the activated carbon 22 of the canister 12.

  In the state of FIG. 6 (B), the fuel vapor hardly floats in the pump module 14 or in the vicinity of the pump passage 20 due to scavenging. Even when a negative pressure is introduced into the evaporated fuel path including the fuel vapor, it is possible to prevent the fuel vapor from being released from the air filter 16 into the atmosphere.

  FIG. 6 (C) shows a case where a negative pressure is introduced into the evaporated fuel path for the leak judgment without scavenging the inside of the pump module 14 by the method of FIG. 5 from the state shown in FIG. 6 (A). Yes. As described above, when the leak determination is performed without scavenging the pump module 14, the fuel vapor floating in the vicinity of the module 14 or the pump passage 20 passes through the air filter 16 by the operation of the negative pressure pump 38. And released into the atmosphere. Further, the operation of the negative pressure pump 38 may cause the fuel vapor adsorbed on the activated carbon 22 in the vicinity of the pump side port 26 to desorb and flow to the pump module 14 side, and the fuel vapor may be discharged into the atmosphere. Is done.

  Therefore, according to the present embodiment, the fuel vapor floating in the pump module 14 is sent to the canister 12 by using the intake negative pressure during the operation of the internal combustion engine, so that the fuel vapor is atmospheric when the leak is detected. It is possible to reliably suppress the release into the inside.

  Next, a processing procedure in the system of the evaporated fuel processing apparatus of this embodiment will be described based on the flowchart of FIG. The process of FIG. 7 is performed every predetermined time. First, in step S1, the purge VSV 36 is opened during operation of the internal combustion engine, and the fuel vapor adsorbed on the canister 12 is purged. In the next step S2, it is determined whether or not the amount of gas (purge amount) that has flowed through the purge VSV 36 during purging is equal to or greater than a predetermined amount (here, A liter). If the purge amount is greater than or equal to A liter, the process proceeds to step S3. On the other hand, when the purge amount is less than A liter, the process proceeds to step S9, and when the negative pressure pump 38 is operating, the operation is stopped.

  In step S2, if the purge amount is less than A liter, the fuel vapor purge amount from the canister 12 to the intake pipe 37 becomes insufficient. In this case, when scavenging is performed by the method of FIG. 5, the fuel vapor adsorbed on the activated carbon 22 in the vicinity of the pump-side port 26 is not completely desorbed, so the fuel sent to the canister 12 during scavenging. It is assumed that the vapor is not reliably adsorbed to the canister 12. If the purge amount is A liter or more, the fuel vapor adsorbed on the activated carbon 22 in the vicinity of the pump side port 26 is reliably purged to the intake pipe 37. Therefore, when scavenging by the method of FIG. The fuel vapor scavenged from the vicinity of the negative pressure pump 38 can be adsorbed to the activated carbon 22 in the vicinity of the pump-side port 26. If the purge amount is A liter or more, the fuel vapor accumulated in the passage connecting the air filter 16 and the negative pressure pump 38 can be sent to the canister 12 side in advance, and the negative pressure pump 38 is operated during scavenging. In this case, it is possible to reliably prevent the fuel vapor from being released into the atmosphere through the air filter 16.

  In step S3, the state of the X pump scavenging flag is detected. Here, the X pump scavenging flag is a flag for determining whether or not the driving of the negative pressure pump 38 is completed when scavenging is performed by the method of FIG. 5, and the driving of the negative pressure pump 38 is completed. If the X pump scavenging flag is set to 1, the X pump scavenging flag is set to 0 if the driving of the negative pressure pump 38 is not completed. The initial value of the X pump scavenging flag is set to zero.

  When the X pump scavenging flag = 0 in step S3, the process proceeds to step S4, and the negative pressure pump 38 is operated. In the next step S5, it is determined whether or not the instantaneous purge flow rate is less than B (liters / minute). If the instantaneous purge flow rate is less than B (liters / minute), the process proceeds to step S6. On the other hand, when the instantaneous purge flow rate is B (liters / minute) or more, the process proceeds to step S9 and the operation of the negative pressure pump 38 is stopped.

  As shown in FIG. 5, when the negative pressure pump 38 is operated for scavenging, a flow is generated that opposes the direction of the flow due to the intake negative pressure toward the pump side port 26, and is directed from the reference orifice 46 toward the negative pressure pump 38. Air flows. At this time, if the absolute value of the negative pressure in the intake pipe 37 is large and the flow rate per unit time (instantaneous purge flow rate) flowing through the purge VSV 36 and flowing into the intake pipe 37 is B (liter / minute) or more, the reference orifice The drive amount of the negative pressure pump 38 for generating the air flow from 46 to the negative pressure pump 38 becomes excessively large, and scavenging is insufficient with the normal drive amount. Therefore, in the process of FIG. 5, only when the instantaneous purge flow rate is less than B (liters / minute), scavenging is performed by operating the negative pressure pump 38, and when the instantaneous purge flow rate is B (liters / minute) or more. The operation of the negative pressure pump 30 is stopped so that scavenging is not performed. Thereby, the drive amount of the negative pressure pump 38 when performing scavenging can be minimized.

  In the next step S6, it is determined whether or not the cumulative driving time of the negative pressure pump 38 during scavenging has passed C hours. Here, time C indicates the time during which the fuel vapor in the pump module 14 is completely scavenged. When C time has not passed, it progresses to step S7, the operation | movement of the negative pressure pump 38 is continued, and scavenging is performed continuously. On the other hand, when C time has passed, it progresses to step S8, X pump scavenging flag = 1 is set, and the operation | movement of the negative pressure pump 38 is stopped by the following step S9. After steps S7 and S9, the process ends (RETURN).

  According to the process of FIG. 7, by operating the negative pressure pump 38 while purging the fuel vapor to the intake pipe 37, the fuel vapor staying in and near the negative pressure pump 38 is removed from the canister. 12 can be sent, and the inside of the pump module 14 can be scavenged.

  As described above, according to the first embodiment, during the operation of the internal combustion engine, when the fuel vapor adsorbed on the canister 12 is purged to the intake pipe 37 using the intake negative pressure, the negative pressure in the pump module 14 is reduced. Since the pressure pump 38 is operated, the fuel vapor staying in and near the negative pressure pump 38 can be scavenged and sent to the canister 12 side by the intake negative pressure. Therefore, it is possible to reliably prevent the fuel vapor from being released into the atmosphere by introducing a negative pressure into the evaporated fuel path when detecting a leak.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. In the second embodiment, the configuration of the pump module 14 is different from that of the first embodiment. FIG. 8 is a schematic diagram showing a system configuration of the second embodiment.

  As shown in FIG. 8, in the second embodiment, a bypass passage 47 that bypasses the check valve 48 of the pump module 14 is provided, and the pump scavenging VSV 49 is provided in the bypass passage 47. At the normal time and at the time of leakage determination, the pump scavenging VSV 49 is closed (OFF state), and the flow from the negative pressure pump 38 to the switching valve 42 is blocked by the function of the check valve 48. When the pump scavenging gas VSV 49 is opened, air can flow from the negative pressure pump 38 toward the switching valve 42 via the bypass channel 47. Other configurations of the second embodiment are the same as those of the first embodiment.

  Also in the second embodiment, the fuel vapor accumulated in the pump module 14 and in the vicinity thereof is scavenged using the intake negative pressure. Hereinafter, a method for scavenging the inside of the pump module 14 and the vicinity thereof will be described with reference to FIGS. 8 and 9.

  When performing scavenging, first, as shown in FIG. 8, the switching valve 42 is set to the state shown in FIG. 2B (VSV-OFF), and the purge VSV 36 is opened during operation of the internal combustion engine. As a result, as described with reference to FIG. 4, the fuel vapor adsorbed on the canister 12 is purged to the intake pipe 37.

  After purging by opening the purge VSV 36 for a predetermined time, the purge VSV 36 is closed. Even after the purge VSV 36 is closed, the intake negative pressure remains in the closed space including the inside of the canister 12.

  After the purge VSV 36 is closed, the switching valve 42 is set to the state shown in FIG. 2A (VSV-ON) as shown in FIG. 9, and the pump scavenging VSV 49 is opened. As a result, the negative intake pressure remaining in the canister 12 causes a flow from the negative pressure pump 38 to the canister 12 through the bypass passage 47 and the passage 42 a or the reference orifice 46.

  When such an air flow occurs, the fuel vapor remaining in or near the negative pressure pump 38 is sent to the canister 12 side. Therefore, the inside of the pump module 14 can be scavenged at or near the negative pressure pump 38. As a result, when a negative pressure is introduced into the evaporated fuel path at the time of leak detection, it is possible to prevent the fuel vapor floating near the negative pressure pump 38 from being released into the atmosphere.

  Further, in the second embodiment, since the scavenging is performed after the purge VSV 36 is closed, it is possible to avoid an excessive increase in the absolute value of the negative pressure in the evaporated fuel path including the canister 12 due to the pressure loss of the negative pressure pump 38. . Thereby, it can suppress that fuel vapor newly generate | occur | produces in the fuel tank 10 by an excessive negative pressure.

  Next, a processing procedure in the system of the evaporated fuel processing apparatus of the second embodiment will be described based on the flowchart of FIG. The process of FIG. 10 is performed every predetermined time. First, in step S11, it is determined whether the switching valve is set to the state shown in FIG. 2B during operation of the internal combustion engine (VSV-OFF), and the purge VSV 36 is opened and the purge is started. . If the purge has started, the process proceeds to step S12. On the other hand, if the purge has not started, the process proceeds to step S17. In step S17, a process of stopping scavenging is performed as will be described later.

  In step S12, it is determined whether the purge is finished and the purge VSV 36 is closed. When the purge VSV 36 is closed, the process proceeds to step S13, and when the purge VSV 36 is not closed, the process proceeds to step S17.

  In step S13, it is determined whether or not a purge of D hours or more has been performed until the purge VSV 36 is closed in step S12. Here, the D time is a time for generating a sufficient negative pressure necessary for scavenging in the closed space including the canister 12 by the purge. When purging for D hours or longer is performed, the negative pressure necessary for scavenging is generated in the closed space including the canister 12, and thus the process proceeds to step S14. On the other hand, if the purge for D hours or more has not been performed, that is, if the purge time is less than D hours, the process proceeds to step S17.

  In step S14, the state of the switching valve 42 is changed to the state shown in FIG. 2A (VSV-ON), the pump scavenging VSV 49 is opened, and the intake negative pressure remaining in the canister 12 causes the negative pressure pump 38 to Alternatively, the fuel vapor remaining in the vicinity thereof is sent to the canister 12 side.

  In the next step S15, it is determined whether or not the time during which scavenging is performed by opening the pump scavenging VSV 49 is within E time. Here, the E time indicates the time during which the fuel vapor in the pump module 14 is completely scavenged. If the scavenging time is within E hours, the process proceeds to step S16. In this case, since the scavenging time is insufficient, in step S16, the switching valve 42 is set to the state shown in FIG. 2A (VSV-ON) and the scavenging is continued with the pump scavenging VSV 49 opened. Do.

  On the other hand, if the time for scavenging exceeds the E time, the process proceeds to step S17. In this case, since scavenging is sufficiently performed, in step S17, the switching valve 42 is set to the state shown in FIG. 2B (VSV-OFF), the pump scavenging VSV 49 is closed, and scavenging is stopped. . After steps S16 and S17, the process ends (RETURN).

  According to the processing of FIG. 10, when a sufficient negative pressure necessary for scavenging is generated in the closed space including the canister 12, the switching valve 42 is set to the state shown in FIG. VSV-OFF) and opening the pump scavenging VSV 49 allows the pump module 14 to be scavenged.

  In the state shown in FIG. 9, when scavenging is performed by opening the pump scavenging VSV 49, the negative pressure of the intake pipe 37 may be introduced to the canister 12 side with the purge VSV 36 opened. However, in this case, since the intake negative pressure is introduced into the fuel tank 10 to newly generate fuel vapor in the fuel tank 10, the purge VSV 36 is closed to suppress the generation of excess fuel vapor. It is preferable to perform scavenging.

  As described above, according to the second embodiment, since the pump scavenging VSV 49 is provided in the pump module 14, the state of the switching valve 42 is set to the state shown in FIG. 2A and the pump scavenging VSV 49 is opened. Thus, it becomes possible to introduce a negative pressure in the vicinity of the negative pressure pump 38. As a result, the fuel vapor staying in and near the negative pressure pump 38 can be scavenged and sent to the canister 12 side by the intake negative pressure. Therefore, it is possible to reliably prevent the fuel vapor from being released into the atmosphere by introducing a negative pressure into the evaporated fuel path when detecting a leak.

  In each of the above-described embodiments, in the system for determining the leak of the evaporated fuel path, negative pressure is introduced into the closed space of the evaporated fuel path including the fuel tank 10, but the present invention is a system for determining the leak. It is also possible to apply to other systems. For example, the negative pressure pump 38 is operated to prevent the fuel vapor from filling the closed space of the evaporated fuel path including the fuel tank 10 when the vehicle equipped with the evaporated fuel processing apparatus of the present embodiment stops. Thus, by introducing a negative pressure into the closed space, it can be applied to various systems such as a system for adsorbing fuel vapor in the closed space to the canister 12. Even in this case, according to each of the above-described embodiments, it is possible to reliably prevent the fuel vapor from being released into the atmosphere.

It is a figure for demonstrating the outline | summary of the evaporative fuel processing apparatus which concerns on each embodiment of this invention. It is a schematic diagram which shows the structure of a pump module. FIG. 6 is a schematic diagram showing a relationship between a transition of an _{actual measurement value} of pressure P detected by a pressure sensor and a reference pressure _PREF when a negative pressure is introduced into an evaporative fuel path including a fuel tank and a canister. It is a schematic diagram which shows a mode that the fuel vapor adsorbed by the canister is purged to the intake pipe. It is a schematic diagram which shows the state which is scavenging in the pump module and its vicinity using an intake negative pressure. It is a schematic diagram which shows the floating state and adsorption state of the fuel vapor in the periphery of a canister. 3 is a flowchart illustrating a processing procedure in the system according to the first embodiment. FIG. 3 is a schematic diagram showing a system configuration of a second embodiment. In Embodiment 2, it is a schematic diagram which shows the method of scavenging the inside of the pump module 14, and its vicinity. 10 is a flowchart illustrating a processing procedure in the system according to the second embodiment.

Explanation of symbols

10 Fuel tank 12 Canister 36 Purge VSV
37 Intake pipe 38 Negative pressure pump 47 Bypass flow path 48 Check valve 49 Pump scavenging VSV

Claims (4)

A fuel tank,
A canister connected to the fuel tank and adsorbing the evaporated fuel generated in the fuel tank;
A pump connected to the canister and for introducing a negative pressure into a closed space including the fuel tank via the canister;
An intake negative pressure introduction valve that is connected to the intake pipe of the internal combustion engine and opens in a predetermined case to introduce the intake negative pressure of the internal combustion engine into the canister;
Scavenging means for sending fuel vapor accumulated in the vicinity of the pump to the canister using the negative intake pressure;
An evaporative fuel processing apparatus comprising: A passage connecting the downstream side of the pump and the canister;
The scavenging means operates the pump in a state where the intake negative pressure is introduced into the canister, thereby sending fuel vapor staying in the vicinity of the pump to the canister via the passage. The evaporative fuel processing apparatus according to claim 1. A check valve provided between the pump and the canister, for blocking air flow from the pump toward the canister;
A bypass flow path that bypasses the check valve and connects the canister and the pump;
A shut-off valve provided in the bypass flow path,
The scavenging means opens the shutoff valve in a state where the pressure due to the intake negative pressure is introduced to the canister, thereby sending fuel vapor staying in the vicinity of the pump to the canister via the bypass flow path. The evaporated fuel processing apparatus according to claim 1.   After the intake negative pressure introduction valve is closed, the scavenging means passes a fuel vapor staying in the vicinity of the pump in a state where pressure due to the intake negative pressure remains in the canister via the bypass flow path. The evaporative fuel processing device according to claim 3, wherein the evaporative fuel processing device is sent to the canister.

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