JP2008095564A - Evaporated fuel treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To selectively execute purge assist and failure diagnosis of leakage by using a purge pump for diagnosis and purge assist. <P>SOLUTION: The apparatus causes a vapor to be purged via a purge line from a canister 21 to an intake passage 2, and changes a flow passage of discharge air from a purge pump 35 to an atmosphere port 25 of the canister 21 by a changeover valve 36 for purpose of purge assist as required, to operate the purge pump 35. On the other hand, in order to block a vapor passage including the canister 21 from an atmosphere line 32 to the purge line 29, the atmosphere line 32 is closed by the changeover valve 36, and the purge line 29 is closed by a purge control valve 30. Then, a pressure is applied by the purge pump 35 to the blocked vapor passage, and subsequently change in pressure is computed based on detected value of a pressure sensor 44, thus leakage failure in the blocked vapor passage is determined from the change in pressure. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an evaporative combustion processing apparatus in which evaporative fuel generated in a fuel tank attached to an internal combustion engine is purged and processed in an intake passage of the internal combustion engine without being diffused into the atmosphere.

  Conventionally, as one of devices mounted on a vehicle, evaporated fuel (vapor) generated in a fuel tank is collected by a canister and purged into an intake passage of an internal combustion engine without being diffused to the atmosphere. There is known an evaporative fuel processing apparatus. This device collects vapor generated in the fuel tank by adsorbing it to the adsorbent inside the canister when the vehicle is stopped or fueled. The fuel component (hydrocarbon (HC), etc.) in the collected vapor is purged into the intake passage using the intake negative pressure generated in the intake passage during the operation of the internal combustion engine. To be processed.

  As this type of technology, Patent Document 1 below describes an example of a fuel vapor processing apparatus. This apparatus is provided with a purge pump, which supplies air to the canister to forcibly remove the vapor from the canister and purge the separated vapor into the intake passage. That is, the purge of the vapor from the canister to the intake passage is assisted by using the purge pump.

JP 2002-332921 A

  However, in the evaporated fuel processing apparatus described in Patent Document 1, the purge pump is provided only for purge assist, and the occupied space of the pump itself is not small. On the other hand, some evaporative fuel processing apparatuses include a failure diagnosis device for self-diagnosis of a leakage failure. Here, it is conceivable to provide an air pump for diagnosing leakage failure and to apply pressure to the inside of the canister or the like. However, in the evaporative fuel processing apparatus described in Patent Document 1, since the purge pump is exclusively used for purge assist, it cannot be used as it is as an air pump for leak failure diagnosis. For this reason, a dedicated air pump has to be provided separately for leak failure diagnosis.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an evaporative fuel processing apparatus that can selectively perform purge assist and leakage failure diagnosis by using a purge pump. It is in.

  In order to achieve the above object, the invention according to claim 1 adsorbs a fuel tank for storing fuel, an atmospheric passage provided for bleeding the fuel tank, and evaporated fuel generated in the fuel tank. A canister provided between the fuel tank and the air passage, a purge pump provided between the canister and the air passage, and an air flow path between the canister, the purge pump and the air passage. A flow path switching means; a purge passage for purging the evaporated fuel adsorbed by the canister into the intake passage of the internal combustion engine; a purge control valve provided in the purge passage for controlling the purge flow rate of the evaporated fuel; and the canister The purge control valve is controlled to purge the evaporated fuel from the intake passage to the intake passage through the purge passage, and the flow path switching means is used to assist the purge if necessary. In order to block the evaporated fuel flow path including the canister from the atmosphere path to the purge path, in the evaporated fuel processing apparatus having a process control means for operating the purge pump and switching the air flow path from the storage pump to the canister, Closure control means for closing the atmospheric passage by the flow path switching means and closing the purge passage by the purge control valve, a pressure sensor for detecting the pressure in the closed evaporated fuel flow path, and the closed evaporated fuel flow path After operating the purge pump to apply pressure to the evaporative fuel flow path, the pressure change is calculated based on the detection result of the pressure sensor, and the leakage failure in the evaporative fuel flow path is determined based on the pressure change. The purpose is to provide a failure determination means for performing.

  According to the configuration of the invention, the evaporated fuel generated in the fuel tank is adsorbed by the canister provided between the fuel tank and the atmospheric passage. The adsorbed evaporated fuel is purged from the canister to the intake passage via the purge passage under the action of the intake negative pressure generated in the intake passage by the processing control means opening the purge control valve during operation of the internal combustion engine. . Further, when the generation of the intake negative pressure becomes insufficient, the processing control means switches the air flow path from the purge pump to the canister by the flow path switching means as necessary, and operates the purge pump. Accordingly, pressure is applied to the canister by the purge pump, and the purge of the evaporated fuel from the canister is assisted. In order to purge the evaporated fuel adsorbed on the canister in this way, a purge control valve and a flow path switching means are used, and a purge pump is used as necessary. On the other hand, in order to diagnose the leakage failure of the apparatus, the blockage control means closes the atmospheric passage by the flow path switching means and closes the purge passage by the purge control valve, so that the evaporated fuel flow including the canister from the atmospheric passage to the purge passage is included. The road is blocked. Thereafter, the failure determination unit operates the purge pump to apply pressure to the blocked evaporated fuel flow path. The failure determination unit calculates a pressure change based on the detection result of the pressure sensor, and based on the pressure change. Judgment of leakage failure in the evaporative fuel flow path is performed.

  In order to achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the process control means executes control for assisting purge during operation of the internal combustion engine, and the failure determination means. The purpose of this is to execute a leakage failure determination when the internal combustion engine is stopped.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 1, purge assist using the purge pump is executed by the process control means during operation of the internal combustion engine in which intake negative pressure is generated in the intake passage. The On the other hand, the diagnosis of leakage failure using the purge pump is executed by the failure determination means when the internal combustion engine with less vibration is stopped.

  In order to achieve the above object, according to a third aspect of the present invention, in the second aspect of the present invention, the purge pump has both a function of a positive pressure pump and a function of a negative pressure pump. The purge pump functions as a positive pressure pump in order to assist, and the failure determination means has the purpose of causing the purge pump to function as a negative pressure pump in order to determine leakage failure.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 2, the processing control means causes the purge pump to function as a positive pressure pump, whereby a positive pressure is applied to the canister and the purge is assisted. When the failure determination means causes the purge pump to function as a negative pressure pump, a negative pressure is applied to the closed evaporated fuel flow path, and a leakage failure is determined.

  In order to achieve the above object, according to a fourth aspect of the present invention, in the second aspect of the present invention, the purge pump has both a function of a positive pressure pump and a function of a negative pressure pump. The purge pump functions as a positive pressure pump in order to assist, and the failure determination means has the purpose of causing the purge pump to function as a positive pressure pump in order to determine leakage failure.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 2, the processing control means causes the purge pump to function as a positive pressure pump, whereby a positive pressure is applied to the canister and the purge is assisted. The failure determination means causes the purge pump to function as a positive pressure pump, so that a positive pressure is applied to the closed evaporated fuel flow path and a leakage failure is determined.

  In order to achieve the above object, according to a fifth aspect of the present invention, in the second aspect of the present invention, the purge pump has both a function of a positive pressure pump and a function of a negative pressure pump. In order to assist, the purge pump functions as a positive pressure pump, and the failure determination means has the purpose of causing the purge pump to function as a positive pressure pump and a negative pressure pump in order to determine a leakage failure.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 2, the processing control means causes the purge pump to function as a positive pressure pump, whereby a positive pressure is applied to the canister and the purge is assisted. The failure determination means causes the purge pump to function as a positive pressure pump and a negative pressure pump, so that a positive pressure and a negative pressure are applied to the closed evaporated fuel flow path, and a leakage failure is determined.

  In order to achieve the above object, according to a sixth aspect of the present invention, in the invention according to any of the third to fifth aspects, the purge pump includes an operating blade and a motor that rotates the operating blade. The processing control means and the failure determination means are intended to selectively function the purge pump as a positive pressure pump or a negative pressure pump by selectively changing the rotation direction of the motor of the purge pump.

  According to the configuration of the above invention, in addition to the operation of the invention according to any one of claims 3 to 5, the function of the purge pump can be set to a positive pressure only by selectively changing the rotation direction of the motor constituting the purge pump. Changed between pump and negative pressure pump.

  In order to achieve the above object, according to a seventh aspect of the present invention, in the invention according to any one of the first to sixth aspects, the canister has an atmospheric port communicating with the atmospheric passage, and the purge pump is connected to the atmospheric port. The purpose is to be provided correspondingly.

  According to the configuration of the invention, in addition to the operation of the invention according to any one of claims 1 to 6, since the purge pump is provided corresponding to the atmospheric port of the canister, the purge pump is used to assist the purge. By functioning as a positive pressure pump, the atmosphere is pushed into the canister with positive pressure.

  In order to achieve the above object, according to an eighth aspect of the present invention, in the invention according to any one of the first to sixth aspects, the canister includes a purge port communicating with the purge passage, and the purge pump is connected to the purge port. The purpose is to be provided correspondingly.

  According to the configuration of the invention, in addition to the action of the invention according to any one of claims 1 to 6, the purge pump is provided corresponding to the purge port of the canister. By functioning as a negative pressure pump, the evaporated fuel is sucked out of the canister by negative pressure and pushed into the intake passage.

  In order to achieve the above object, according to a ninth aspect of the present invention, in the invention according to any one of the first to sixth aspects, the canister includes an evaporative fuel port communicating with the fuel tank, and the purge pump includes the evaporative fuel. The purpose is to be provided corresponding to the port.

  According to the configuration of the invention, in addition to the operation of the invention according to any one of claims 1 to 6, since the purge pump is provided corresponding to the evaporated fuel port of the canister, the purge is performed in order to assist the purge. By causing the pump to function as a positive pressure pump, the atmosphere is pushed into the canister with positive pressure.

  In order to achieve the above object, according to a tenth aspect of the present invention, in the seventh aspect of the invention, the purge passage is provided on the downstream side of the plurality of branch passages so as to communicate with the intake passage. The purge control valve is provided in each of the plurality of branch paths.

  According to the configuration of the above invention, in addition to the action of the invention of claim 7, since the purge passage is branched into a plurality of branch paths, the flow rate of the evaporated fuel to be purged is increased by the number of branch paths. In addition, since a purge control valve is provided in each branch path, the flow rate of the evaporated fuel to be purged can be increased or decreased by controlling the purge control valve as necessary.

  In order to achieve the above object, according to an eleventh aspect of the present invention, in the tenth aspect of the present invention, a throttle valve is provided in the intake passage, and the purge passage branches into two branch passages downstream thereof. One of the branch passages is provided in communication with the intake passage on the upstream side of the throttle valve, and the other branch passage is provided in communication with the intake passage on the downstream side of the throttle valve. .

  According to the configuration of the above invention, in addition to the operation of the invention of claim 10, one of the two branched paths communicates with the intake passage upstream of the throttle valve, and the other branched path is the throttle. Since it communicates with the intake passage on the downstream side of the valve, the evaporated fuel is distributed over a wide range of the intake passage.

  In order to achieve the above object, according to a twelfth aspect of the present invention, in the eighth aspect of the invention, the purge passage is provided on the downstream side of the plurality of branch passages so as to communicate with the intake passage. The purge control valve is provided in each of the plurality of branch paths.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 8, since the purge passage is branched into a plurality of branch passages, the flow rate of the evaporated fuel to be purged is increased by the number of branch passages. In addition, since a purge control valve is provided in each branch path, the flow rate of the evaporated fuel to be purged can be increased or decreased by controlling the purge control valve as necessary.

  In order to achieve the above object, according to a thirteenth aspect of the present invention, in the thirteenth aspect of the present invention, a throttle valve is provided in the intake passage, and the purge passage branches into two branch passages downstream thereof. One of the branch passages is provided in communication with the intake passage on the upstream side of the throttle valve, and the other branch passage is provided in communication with the intake passage on the downstream side of the throttle valve. .

  According to the configuration of the above invention, in addition to the operation of the invention according to claim 12, one of the two branched branches communicates with the intake passage on the upstream side of the throttle valve, and the other branched path is the throttle. Since it communicates with the intake passage on the downstream side of the valve, the evaporated fuel is purged into the intake passage with good distribution.

  In order to achieve the above object, according to a fourteenth aspect of the present invention, in the invention according to the ninth aspect, the purge passage is provided on the downstream side of the plurality of branch passages so as to communicate with the intake passage. The purge control valve is provided in each of the plurality of branch paths.

  According to the configuration of the above invention, in addition to the action of the invention according to claim 9, since the purge passage is branched into a plurality of branch passages, the flow rate of the evaporated fuel to be purged is increased by the number of branch passages. In addition, since a purge control valve is provided in each branch path, the flow rate of the evaporated fuel to be purged can be increased or decreased by controlling the purge control valve as necessary.

  In order to achieve the above object, according to a fifteenth aspect of the present invention, in the thirteenth aspect of the present invention, a throttle valve is provided in the intake passage, and the purge passage branches into two branch passages downstream thereof. One of the branch passages is provided in communication with the intake passage on the upstream side of the throttle valve, and the other branch passage is provided in communication with the intake passage on the downstream side of the throttle valve. .

  According to the configuration of the invention described above, in addition to the operation of the invention described in claim 14, one of the two branched passages communicates with the intake passage on the upstream side of the throttle valve, and the other branched passage is the throttle. Since it communicates with the intake passage on the downstream side of the valve, the evaporated fuel is purged into the intake passage with good distribution.

  In order to achieve the above object, according to a sixteenth aspect of the present invention, in the invention according to any one of the first to sixth aspects, at least the purge pump and the flow path switching means are provided in the fuel tank. The purpose.

  According to the configuration of the above invention, in addition to the operation of the invention according to any one of claims 1 to 6, at least the purge pump and the flow path switching means are provided in the fuel tank, so that the mounting space is omitted accordingly. Is done.

  According to the first aspect of the present invention, the purge assist and the leakage failure diagnosis can be selectively performed by using the purge pump together, and the fuel vapor processing apparatus can be downsized.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, since purge assist and leakage fault diagnosis are performed at different times, these processes are performed using one purge pump. In addition, the accuracy of leakage failure diagnosis can be improved by the amount that there is no adverse effect of vibration.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 2, purge assist by applying positive pressure and leakage failure diagnosis by applying negative pressure can be performed by one purge pump. .

  According to the invention described in claim 4, in addition to the effect of the invention described in claim 2, purge assist by applying positive pressure and leakage failure diagnosis by applying positive pressure can be performed by one purge pump. .

  According to the invention described in claim 5, in addition to the effect of the invention described in claim 2, purge assist by applying positive pressure and leakage failure diagnosis by applying positive and negative pressure are performed by one purge pump. be able to.

  According to the invention described in claim 6, in addition to the effects of the invention described in any one of claims 3 to 5, the function of the positive pressure pump and the function of the negative pressure pump by a single purge pump with a relatively simple configuration. Can be obtained.

  According to the invention described in claim 7, in addition to the effect of the invention described in any one of claims 1 to 6, the vapor adsorbed by the canister can be pushed out from the canister, and the vapor adsorption capacity of the canister is set to the initial state. Can be restored to a state close to.

  According to the invention described in claim 8, in addition to the effect of the invention described in any one of claims 1 to 6, the responsiveness of the purge assist can be improved.

  According to the invention described in claim 9, in addition to the effect of the invention described in any one of claims 1 to 6, the vapor adsorbed by the canister can be pushed out from the canister, and the vapor adsorption capacity of the canister is set to the initial state. Can be restored to a state close to.

  According to the invention described in claim 10, in addition to the effect of the invention described in claim 7, the purged vapor flow rate can be adjusted over a wide range from a small flow rate to a large flow rate.

  According to the eleventh aspect of the invention, in addition to the effect of the tenth aspect of the invention, the vapor can be efficiently purged into the intake passage, and the vapor is removed until the intake pressure in the intake passage becomes close to atmospheric pressure. Purge can be performed, and the flow rate of the vapor to be purged can be easily controlled.

  According to the invention described in claim 12, in addition to the effect of the invention described in claim 8, the purged vapor flow rate can be adjusted over a wide range from a small flow rate to a large flow rate.

  According to the invention described in claim 13, in addition to the effect of the invention described in claim 12, the vapor can be efficiently purged into the intake passage, and the vapor is removed until the intake pressure in the intake passage becomes close to the atmospheric pressure. Purge can be performed, and the flow rate of the vapor to be purged can be easily controlled.

  According to the invention described in claim 14, in addition to the effect of the invention described in claim 9, the purged vapor flow rate can be adjusted over a wide range from a small flow rate to a large flow rate.

  According to the invention of the fifteenth aspect, in addition to the effect of the invention of the fourteenth aspect, the vapor can be efficiently purged into the intake passage, and the vapor is removed until the intake pressure in the intake passage becomes close to the atmospheric pressure. Purge can be performed, and the flow rate of the vapor to be purged can be easily controlled.

  According to the invention described in claim 16, in addition to the effect of the invention described in any one of claims 1 to 6, the purge pump and the flow path switching means can be protected in the fuel tank. The noise caused by the operation sound can be suppressed.

[First Embodiment]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment that embodies an evaporative fuel processing apparatus of the present invention will be described in detail below with reference to the drawings.

  FIG. 1 shows a schematic configuration diagram of an engine system and a fuel vapor processing apparatus mounted on an automobile. An engine 1 serving as an internal combustion engine constituting the engine system includes an intake passage 2 that sucks outside air and an exhaust passage 3 that discharges exhaust gas. The engine 1 is provided with injectors 4 corresponding to a plurality of combustion chambers (not shown). The engine system further includes a fuel tank 5 that stores fuel. The fuel tank 5 is provided with a fuel supply pipe 7 including a fuel filler 6. Fuel is supplied to the fuel tank 5 by opening the fuel filler 6 and injecting fuel into the fuel pipe 7. A fuel pump 8 is built in the fuel tank 5. The fuel discharged from the fuel tank 5 by the fuel pump 8 is supplied to each injector 4 through the fuel line 9. The supplied fuel is injected into the intake passage 2 when each injector 4 is operated. Air that has been purified through the air cleaner 10 is introduced into the intake passage 2. A mixture of the air and the injected fuel is introduced into each combustion chamber. The introduced air-fuel mixture explodes and burns when an ignition device (not shown) operates in each combustion chamber. The exhaust gas after combustion is discharged to the outside through the exhaust passage 3.

  The intake passage 2 is provided with a throttle valve 11 that is opened and closed to adjust the intake air amount. The throttle valve 11 is provided with a throttle sensor 41 for detecting its opening degree (throttle opening degree) TA. The intake passage 2 is provided with an intake pressure sensor 42 for detecting the intake pressure PM. The engine 1 is provided with a rotation speed sensor 43 for detecting the rotation speed (engine rotation speed) NE. The throttle sensor 41, the intake pressure sensor 42, and the rotation speed sensor 43 correspond to an operation state detection unit for detecting the operation state of the engine 1.

  An evaporative fuel processing device is mounted on an automobile. This apparatus is for collecting and processing the evaporated fuel (vapor) generated in the fuel tank 5 without diffusing (releasing) it into the atmosphere. This apparatus includes a canister 21 for adsorbing vapor generated in the fuel tank 5, and an adsorbent 22 made of activated carbon is built in the canister 21 to adsorb the vapor.

  The canister 21 includes an evaporated fuel port (vapor port) 23 for introducing vapor generated in the fuel tank 5, a purge port 24 for purging the vapor collected in the canister 21, and the interior of the canister 21. And an atmosphere port 25 for introducing the atmosphere into the atmosphere. A vapor line 26 extending from the fuel tank 5 communicates with the vapor port 23 via a vapor control valve 27. A float valve 28 is provided at the inlet of the vapor line 26 in the fuel tank 5. A purge line 29 as a purge passage extending from the purge port 24 communicates with the intake passage 2 downstream from the throttle valve 11. A purge control valve 30 is provided in the middle of the purge line 29. The purge line 29 is for purging the vapor adsorbed by the canister 21 to the intake passage 2. The opening degree of the purge control valve 30 is controlled in order to control the purge flow rate of the vapor in the purge line 29. An atmospheric line 32 as an atmospheric passage extending from the atmospheric port 25 through the pump assembly 31 has its tip opened to the atmosphere. An air filter 33 is provided in the middle of the atmospheric line 32.

  The vapor control valve 27 controls the vapor led from the fuel tank 5 to the canister 21 and is constituted by a diaphragm type check valve that operates under pressure. The vapor control valve 27 is opened and closed by operating a diaphragm based on a differential pressure between the pressure in the vapor line 26 and the fuel tank 5 (tank side internal pressure) and the pressure in the canister 21 (canister side internal force). I speak. That is, the vapor control valve 27 is opened when the internal pressure on the canister side is almost the same as the atmospheric pressure and the internal pressure is smaller than the internal pressure on the tank side, so that the vapor flow from the fuel tank 5 to the canister 21 is allowed. The On the other hand, the vapor control valve 27 is opened when the internal pressure on the canister side becomes larger than the internal pressure on the tank side, so that the gas flow from the canister 21 to the fuel tank 5 is allowed.

  The canister 21 adsorbs and collects the vapor introduced inside through the vapor line 26 and the vapor port 23 by the adsorbent 22, and collects only the gas containing no fuel components (hydrocarbon (HC), etc.) in the vapor into the atmospheric port 25. Then, the air is discharged into the atmosphere through the air line 30 and the air filter 31 through the pump assembly 31. Further, during operation of the engine 1, intake negative pressure generated in the intake passage 2 acts on the purge line 29. At this time, by opening the purge control valve 30, the vapor adsorbed by the canister 21 is purged to the intake passage 2 through the purge line 29. The purge control valve 30 is composed of an electromagnetic valve, and its opening degree is duty-controlled in order to control the purge flow rate.

  The pump assembly 31 includes a purge pump 35, a three-way switching valve 36 corresponding to a flow path switching means, a pressure sensor 44, and a relief valve 37, and these components 35 to 37, 44 are modularized. . The purge pump 35 is provided between the canister 21 and the atmospheric line 32 in order to apply pressure to the canister 21 through the atmospheric port 25. The purge pump 35 is composed of a vane pump and includes a working blade and a motor that rotates the working blade. The purge pump 35 is provided for the purpose of assisting purge from the canister 21 and is configured to discharge a large amount of air. In this embodiment, for purge assist, for example, the operation is performed with a load of about 60 to 120 (L / min). The purge pump 35 may be a Wesco type pump. The three-way switching valve 36 is provided to switch the air flow path between the atmospheric air port 25 of the canister 21, the pump flow path 38 communicating with the discharge port of the purge pump 35, and the atmospheric air line 32, and is configured by an electromagnetic valve. The That is, the three-way switching valve 36 is switched so that the pump flow path 38 is shut off and the atmospheric port 25 and the atmospheric line 32 are communicated, and the atmospheric line 32 is blocked, and the atmospheric port 25 and the pump flow path are connected. 38 to be communicated with each other. A bypass passage 39 is provided between the atmosphere line 32 on the atmosphere side of the three-way switching valve 35 and the pump flow path 38. The relief valve 37 is provided in the bypass passage 39, restricts the flow of air from the atmospheric line 32 to the pump flow path 38, and allows the air flow in the opposite direction. The pressure sensor 44 is provided so as to detect the pressure in the pump flow path 38.

  In this embodiment, the driver's seat of the automobile is provided with a notification lamp 20 for notifying the driver or the like that an abnormality such as a leakage failure has occurred in the evaporated fuel processing device.

  In this embodiment, an electronic control unit (ECU) 50 is provided to control the fuel vapor processing apparatus. The various sensors 41 to 44 described above are connected to the ECU 50. Similarly, the injector 4, the fuel pump 8, the notification lamp 20, the purge control valve 30, the purge pump 35, and the three-way switching valve 36 are connected to the ECU 50, respectively. In this embodiment, in order to control the purge flow rate of the vapor from the canister 21 according to the operating state of the engine 1, the ECU 50 controls the purge control valve 30 based on the detection signals of the various sensors 41 to 43, and if necessary Thus, the purge pump 35 and the three-way switching valve 36 are controlled. On the other hand, in this embodiment, the ECU 50 controls the purge pump 35 and the three-way switching valve 36 based on the detection signals of the various sensors 41 to 43 in order to diagnose the leakage failure of the evaporated fuel processing apparatus, and the pressure sensor 44 Based on the detection result, a leakage failure is determined and the notification lamp 20 is controlled.

  As is well known, the ECU 50 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), a backup RAM, an external input circuit, an external output circuit, and the like. Various control programs and predetermined data are stored in advance in the ROM. The calculation result of the CPU is temporarily stored in the RAM. Data stored in advance is stored in the backup RAM. The CPU executes various controls based on detection signals from the various sensors 41 to 44 input via the input circuit. The ECU 50 corresponds to the processing control means, the blockage control means, and the failure determination means in the present invention.

  Next, the contents of the purge control executed by the ECU 50 will be described. FIG. 2 is a flowchart showing the purge control program.

  First, in step 100, the ECU 50 determines whether or not the engine 1 is in operation. The ECU 50 makes this determination based on the detection signal of the rotation speed sensor 43 and the like. If this determination is affirmative, the ECU 50 proceeds to step 110.

  In step 110, the ECU 50 determines whether a predetermined purge condition for executing the purge is satisfied. Here, the purge condition may be, for example, an operating state in which an intake negative pressure necessary for purging is generated in the intake passage 2 downstream from the throttle valve 11. If this determination is affirmative, the ECU 50 proceeds to step 120.

  In step 120, the ECU 50 executes a purge process. In this embodiment, the ECU 50 opens the purge control valve 30 and controls the three-way switching valve 36 to a predetermined switching state. Here, as shown in FIG. 4B, the three-way switching valve 36 is switched so as to shut off the pump flow path 38 and allow the atmospheric port 25 and the atmospheric line 32 to communicate with each other. As shown in FIG. 4A, the switching state of the three-way switching valve 36 during the purge process is the same as the switching state when the engine 1 is stopped and when the vehicle is parked or when fuel is supplied to the fuel tank 5. It is. The purge control valve 30 may simply be fully opened, or the opening degree may be controlled according to the operating state of the engine 1.

  Next, in step 130, the ECU 50 determines whether or not purge assist is started. Here, the purge assist can be started, for example, when the intake passage 2 downstream of the throttle valve 11 is in an operating state in which the intake negative pressure necessary for purging is unlikely to occur. If this determination is negative, the ECU 50 repeats the processing from step 110. On the other hand, if this determination is affirmative, the ECU 50 proceeds to step 140.

  In step 140, the ECU 50 executes a purge assist process. In this embodiment, the ECU 50 operates the purge pump 35 with a load of 60 to 120 (L / min) and controls the three-way switching valve 36 to a predetermined switching state. Here, as shown in FIG. 4 (c), the purge pump 35 is operated normally (motor is rotated forward), and the three-way switching valve 36 shuts off the atmospheric line 32 and is connected to the atmospheric port 25 and the pump flow. It is switched so as to communicate with the road 38. Thus, a positive pressure is applied to the canister 21 by the purge pump 35, and vapor purge from the canister 21 to the intake passage 2 is assisted. Here, the rotational speed of the motor of the purge pump 35 may be controlled in order to control the positive pressure applied to the canister 2 for purge assist.

  Thereafter, in step 150, the ECU 50 determines whether or not purge assist is finished. For example, the purge assist is terminated when the intake passage 2 downstream of the throttle valve 11 returns to an operation state in which the intake negative pressure necessary for purging is sufficiently generated. When this determination is negative, the ECU 50 repeats the processing from step 140. On the other hand, if this determination is affirmative, the ECU 50 ends the purge assist process in step 160 and returns the process to step 110. That is, the ECU 50 stops the purge pump 35 and returns the three-way switching valve 36 to the switching state shown in FIG.

  Next, the contents of leakage failure diagnosis control executed by the ECU 50 will be described. FIG. 3 is a flowchart showing the leakage failure diagnosis control program.

  First, in step 200, the ECU 50 determines whether or not the engine 1 is stopped. The ECU 50 makes this determination based on the detection signal of the rotation speed sensor 43 and the like. If this determination is affirmative, the ECU 50 proceeds to step 210.

  In step 210, the ECU 50 determines whether a predetermined failure diagnosis condition for executing the leakage failure diagnosis is satisfied. Here, as the failure diagnosis condition, for example,. If this determination is affirmative, the ECU 50 proceeds to step 220.

  In step 220, the ECU 50 executes a vapor flow path closing process. In this embodiment, the ECU 50 closes the purge control valve 30 and controls the three-way switching valve 36 to a predetermined switching state. Here, as shown in FIG. 4D, the three-way switching valve 36 is switched so as to shut off the atmospheric line 32 and to communicate the atmospheric port 25 and the pump flow path 38. As a result, the evaporated fuel flow path (vapor flow path) including the canister 21 from the atmospheric line 32 to the purge line 29 is blocked t. As shown in FIG. 4C, the switching state of the three-way switching valve 36 at the time of the vapor flow path closing process is the same as the switching state during purge assist.

  Thereafter, in step 230, the ECU 50 turns on the purge pump 35. In this embodiment, as shown in FIG. 4D, the ECU 50 reversely operates the purge pump 35 (reverses the motor). As a result, a negative pressure is applied to the blocked vapor flow path (closed space) by the purge pump 35. Here, the purge pump 35 is operated with a load of about 1 (L / min), for example. That is, in this embodiment, the function of the purge pump 35 is changed between the positive pressure pump and the negative pressure pump only by selectively changing the rotation direction of the motor constituting the purge pump 35.

  Next, in step 240, the ECU 50 reads the pressure detected by the pressure sensor 44, and in step 250, determines whether or not the read detected pressure has reached a predetermined value. That is, it is determined whether or not the internal pressure of the closed vapor channel has reached a predetermined negative pressure value. When this determination result is negative, the ECU 50 repeats the processing from step 230. On the other hand, if the determination result is affirmative, the ECU 50 proceeds to step 260.

  In step 260, the ECU 50 determines whether or not a predetermined time has elapsed since the detected pressure reached a predetermined value. If the determination result is affirmative, the ECU 50 proceeds to step 270.

  In step 270, the ECU 50 reads the pressure detected by the pressure sensor 44. In step 280, the ECU 50 calculates a pressure difference between the read value of the detected pressure and the predetermined value used as a reference in step 250. This pressure difference represents the presence or absence of a leakage failure in the vapor channel. Leakage failure means that holes or the like that cause vapor leakage exist in the vapor flow path.

  Thereafter, in step 290, the ECU 50 determines whether or not the calculated pressure difference is greater than or equal to a predetermined value. A diagnostic method for diagnosing the pressure change in the closed vapor flow path is called an “internal pressure monitoring method”. If this determination result is negative, assuming that there is no leakage failure in the vapor flow path, in step 300, the ECU 50 executes normality determination processing, and then ends the subsequent processing. As normality determination processing, the ECU 50 can include processing such as turning off the notification lamp 20 and storing a normal code indicating that there is no leakage failure in the backup RAM.

  On the other hand, if the determination result in step 290 is affirmative, it is assumed that there is a leakage failure in the vapor flow path, and in step 310, the ECU 50 executes an abnormality determination process and temporarily terminates the subsequent processes. As the abnormality determination process, the ECU 50 can include a process of turning on or blinking the notification lamp 20 and storing an abnormality code indicating that there is a leakage failure in the backup RAM.

  According to the evaporative fuel processing apparatus of this embodiment described above, the vapor generated in the fuel tank 5 is adsorbed by the canister 21 provided between the fuel tank 5 and the atmospheric line 32. The adsorbed vapor is purged from the canister 21 to the intake passage 2 through the purge line 29 under the action of the intake negative pressure generated in the intake passage 2 when the ECU 50 opens the purge control valve 30 during operation of the engine 1. Is done. The vapor purge flow rate in the purge line 29 is adjusted by the ECU 50 controlling the opening degree of the purge control valve 29. Further, in this embodiment, when the generation of the intake negative pressure in the intake passage 2 becomes insufficient, the ECU 50 causes the three-way switching valve 36 to connect the air flow path from the purge pump 35 to the canister 21 as necessary. Switch to the atmospheric port 25 and operate the purge pump 35. Thereby, a positive pressure is applied to the canister 21 by the purge pump 35, and the purge of vapor from the canister 21 is assisted. In order to purge the vapor adsorbed on the canister 21 in this way, the purge control valve 30 and the three-way switching valve 36 are used, and the purge pump 35 is used as necessary. Here, the three-way switching valve 36 is switched in order to introduce the atmosphere necessary for purging from the atmospheric line 32 to the canister 21.

  On the other hand, in order to diagnose a leakage failure in the fuel vapor processing apparatus, the ECU 50 closes the atmospheric line 32 with the three-way switching valve 36 and closes the purge line 29 with the purge control valve 30, so that the purge line 29 is changed from the atmospheric line 32. The space of the vapor channel including the canister 21 is closed. Thereafter, the ECU 50 reversely operates the purge pump 35 to apply a negative pressure to the closed vapor passage space, and the ECU 50 calculates a pressure difference that is a pressure change within a predetermined time based on the detection result of the pressure sensor 44. Then, the leakage failure in the vapor passage space is determined based on the pressure difference. Therefore, in order to diagnose a leakage failure in the fuel vapor processing apparatus, the purge control valve 30, the three-way switching valve 36, and the purge pump 35 that are used for purge or purge assist are also used. For this reason, the purge assist and leak failure diagnosis can be selectively performed by using one purge pump 35 as a whole, and the evaporated fuel processing device can be reduced in size by not providing a dedicated air pump for leak failure diagnosis. Can be planned.

  In this embodiment, assist for purge using the purge pump 35 is executed by the ECU 50 during operation of the engine 1 in which intake negative pressure is generated in the intake passage 2. On the other hand, the leakage failure diagnosis using the purge pump 35 is executed by the ECU 50 when the engine 1 with less vibration is stopped. Accordingly, since the purge assist and the leakage fault diagnosis are performed at different times, each process can be performed by using one purge pump 35, and the diagnosis accuracy of the leakage fault is improved by the amount of no adverse influence of vibration. Can be made.

  In this embodiment, the ECU 50 causes the purge pump 35 to function as a positive pressure pump, whereby a positive pressure is applied to the canister 21 to assist the purge. On the other hand, when the ECU 50 causes the purge pump 35 to function as a negative pressure pump, a negative pressure is applied to the closed vapor flow path, and a leakage failure is determined. For this reason, purge assist by applying positive pressure and diagnosis of leakage failure by applying negative pressure can be performed by one purge pump 35. In addition, in this embodiment, since the purge pump 35 that can discharge a large flow rate air dedicated to purge assist is used, it is possible to discharge a small flow rate air necessary for leakage failure diagnosis. For this reason, unlike the case where an air pump dedicated to leakage failure diagnosis is used for purge assist, a large flow rate air necessary and sufficient for purge assist can be supplied to the canister 21.

  In this embodiment, the function of the purge pump 35 is changed between the positive pressure pump and the negative pressure pump only by selectively changing the rotation direction of the motor constituting the purge pump 35. For this reason, the function of a positive pressure pump and the function of a negative pressure pump can be acquired by one purge pump 35 with a comparatively simple structure.

  In this embodiment, although the purge pump 35 is included, the pump assembly 31 is provided corresponding to the atmospheric port 25 of the canister 21, so that the purge pump 35 functions as a positive pressure pump in order to assist the purge. Is pushed into the canister 21 with positive pressure. For this reason, the vapor adsorbed by the adsorbent 22 of the canister 21 can be pushed out of the canister 21 with the purge assist, and the vapor adsorption capacity of the canister 21 can be restored to a state close to the initial state.

[Second Embodiment]
Next, a second embodiment in which the fuel vapor processing apparatus of the present invention is embodied will be described in detail with reference to the drawings.

  In addition, in this 2nd Embodiment and each embodiment demonstrated below, about the same structure as 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted and it demonstrates centering on a different point below.

  This embodiment differs from the first embodiment in the configuration and method related to leakage fault diagnosis. As shown in FIGS. 5A to 5E, in this embodiment, a bypass passage 51 is provided between the atmospheric port 25 of the canister 21 and the relief valve 37, and an orifice hole of φ0.5 is provided in the passage 51. 52 is provided. In this embodiment, a “reference method” is employed as a leakage failure diagnosis method, and the bypass passage 51 and the orifice hole 52 are used to detect a “reference pressure” to be described later. The orifice hole 52 assumes a leakage failure due to a hole of φ0.5.

  In this embodiment, as shown in FIGS. 5A to 5C in comparison with FIGS. 4A to 4C, “parking, refueling”, “purge”, and “purge assist”. The switching state of the three-way switching valve 36 is the same as that of the first embodiment. In this embodiment, the switching of the three-way switching valve 36 is different from that of the first embodiment in leak failure diagnosis.

  In the “reference method”, first, as shown in FIG. 5 (d), the three-way switching valve 36 is held in a neutral position, thereby blocking the pump flow path 38, the atmospheric port 25, and the atmospheric line 32 from each other. To do. In this state, the purge pump 35 is reversely operated to apply a negative pressure to the bypass passages 39 and 51. At this time, the pressure detected by the pressure sensor 44 is detected as a reference pressure assuming a leakage failure due to the orifice hole 52.

  Thereafter, as shown in FIG. 5E, the three-way switching valve 36 is switched so that the atmospheric line 32 is shut off and the atmospheric port 25 and the pump flow path 38 are communicated. Thereby, the vapor flow path including the canister 21 from the atmospheric line 32 to the purge line 29 is closed. In this state, the purge pump 35 is operated in reverse. As a result, a negative pressure is applied to the blocked vapor flow path (closed space) by the purge pump 35. Then, the presence or absence of a leakage failure is determined by comparing the pressure detected by the pressure sensor 44 with the reference pressure described above. Here, when the pressure detected by the pressure sensor 44 approximates the reference pressure, it can be determined that a leak failure has occurred in the vapor flow path, such as a hole that causes vapor leakage.

  Therefore, in this embodiment, the same operational effects as in the first embodiment can be obtained except for the difference in the leakage failure diagnosis method.

[Third Embodiment]
Next, a third embodiment that embodies the fuel vapor processing apparatus of the present invention will be described in detail with reference to the drawings.

  FIG. 6 is a schematic configuration diagram showing the engine system of this embodiment. In this embodiment, the purge line 29 is provided on the downstream side of the plurality of branch passages 29a and 29b so as to communicate with the intake passage 2, and the purge control valve 30A is provided in each of the plurality of branch passages 29a and 29b. , 30B is different from the first and second embodiments in configuration. More specifically, the purge line 29 branches into two parts, a first branch path 29a and a second branch path 29b, on the downstream side, and one of the first branch paths 29a is on the downstream side of the throttle valve 11. The other second branch passage 29 b is provided in communication with the intake passage 2 on the upstream side of the throttle valve 11. The first branch path 29a is provided with a first purge control valve 30A, and the second branch path 29b is provided with a second purge control valve 30B. The ECU 50 controls the purge control valves 30A and 30B. In this embodiment, the second purge control valve 30B can flow a larger amount of vapor than the first purge control valve 30A. For example, the maximum flow rate of the second purge control valve 30B can be set to about 6 times the maximum flow rate of the first purge control valve 30A.

  The purge control of this embodiment is different from the contents of the first embodiment in the following points. The contents of the purge control program of this embodiment will be described with reference to the flowchart shown in FIG.

  That is, also in this embodiment, the ECU 50 basically executes processing equivalent to steps 100 to 160 in FIG. However, in this embodiment, in step 120, the ECU 50 controls to open only the first purge control valve 30A in order to execute the purge process. At this time, the second purge control valve 30B is in a closed state. That is, when a moderate intake negative pressure is generated on the downstream side of the throttle valve 11, only the first purge control valve 30A is controlled, and the intake negative pressure is effectively used to moderate the vapor of the canister 21. Purge.

  In this embodiment, in step 140, the ECU 50 operates the purge pump 35 and controls the three-way switching valve 36 to the switching state as shown in FIG. 4C in order to execute the purge assist process. To do. In addition, the ECU 50 controls the opening of both the first purge control valve 30A and the second purge control valve 30B. Thus, a positive pressure is applied to the canister 21 by the purge pump 35, and vapor purge from the canister 21 to the intake passage 2 is assisted. Here, since the first and second purge control valves 30A and 30B are opened, the vapor pushed out of the canister 21 is purged to the intake passage 2 through both the first and second branch passages 29a and 29b. As a result, a large flow rate of vapor can be quickly purged into the intake passage 2.

  In this embodiment, in step 160, the ECU 50 stops the purge pump 35 and returns the three-way switching valve 36 to the switching state shown in FIG. The purge control valve 30B is closed.

  Therefore, according to the evaporated fuel processing apparatus of this embodiment, since the purge line 29 is branched into the plurality of branch paths 29a and 29b, the vapor flow rate to be purged is increased by the number of the branch paths 29a and 29b. Become. Further, since the purge control valves 30A and 30B are provided in the respective branch paths 29a and 29b, the flow rate of vapor to be purged can be increased or decreased by controlling the purge control valves 30A and 30B as necessary. Become. Therefore, the purged vapor flow rate can be adjusted over a wide range from a small flow rate to a large flow rate.

  In this embodiment, the first branch passage 29a communicates with the intake passage 2 on the downstream side of the throttle valve 11, and the second branch passage 29b communicates with the intake passage 2 on the upstream side of the throttle valve 11. Vapor is distributed over a wide area of the intake passage 2. For this reason, the vapor can be efficiently purged into the intake passage 2. In particular, in this embodiment, since the intake passage 2 can be purged upstream of the throttle valve 11 through the second branch passage 29b, the vapor can be purged until the intake pressure in the intake passage 2 is close to atmospheric pressure. It is possible to easily control the purged vapor flow rate. Other functions and effects are basically the same as those of the first embodiment.

[Fourth Embodiment]
Next, a fourth embodiment that embodies the evaporated fuel processing apparatus of the present invention will be described in detail with reference to the drawings.

  FIG. 7 shows a schematic configuration diagram of the engine system of this embodiment. This embodiment differs from the first embodiment in the configuration and arrangement of the pump assembly 61. That is, in this embodiment, the purge pump 35 is included, but the pump assembly 61 is provided in the middle of the purge line 29 corresponding to the purge port 24 of the canister 21.

  The pump assembly 61 of this embodiment includes a purge pump 35, three three-way switching valves 62, 63, 64, a pressure sensor 44, a relief valve 37, and one on-off valve 65. 37, 44, 62 to 65 are modularized. The three three-way switching valves 62 to 64 and the one on-off valve 65 correspond to the flow path switching means of the present invention. The purge pump 35 is provided between the canister 21 and the atmospheric line 32 in order to apply pressure to the canister 21 through the purge line 29 and the purge port 24. That is, the purge pump 35 is provided in the pump flow path 66 located in the middle of the purge line 29. A first three-way switching valve 62 and a second three-way switching valve 63 are provided on the upstream side and the downstream side of the purge pump 35 in the pump channel 66. A pressure sensor 44 is provided between the first three-way switching valve 62 and the purge pump 35 in order to detect the pressure in the pump flow path 66. The first and second ports of the first and second three-way switching valves 62 and 63 communicate with the pump flow path 66, respectively. The third port of the first three-way switching valve 62 communicates with the first port of the third three-way switching valve 64. The third port of the second three-way switching valve 63 communicates with the second port of the third three-way switching valve 64 and the vicinity of the atmospheric port 25 (the atmospheric line 32) of the canister 21 via the pipe 67a. The third port of the third three-way switching valve 64 communicates with the vicinity of the atmospheric port 25 (the atmospheric line 32) of the canister 21 through the pipe 67b. The pump passage 66 is provided with first and second bypass passages 68 a and 68 b between the upstream side of the first three-way switching valve 62 and the downstream side of the second three-way switching valve 63. Among these, the relief valve 37 is provided in the first bypass passage 68a, and the open / close valve 65 is provided in the second bypass passage 68b. The relief valve 37 allows the backflow of air in the first bypass passage 68a. The components 35, 37, 44, 62 to 65 are electrically connected to the ECU 50, and the purge pump 35, the three-way switching valves 62 to 64, and the on-off valve 65 are controlled by the ECU 50. Yes.

  Next, control of each of 35, 37, 44, 62 to 65 constituting the pump assembly 61 will be described with reference to FIGS. FIGS. 8A to 8D are similar to FIGS. 4A to 4D related to the “internal pressure monitoring method” already described. In this embodiment, at the time of “parking and refueling”, as shown in FIG. 8A, the three-way switching valves 62 to 64 are switched, the on-off valve 65 is closed, and the purge pump 35 is stopped. Yes. Thereby, the flow of air from the atmospheric port 25 of the canister 21 to the atmospheric line 32 is allowed.

  Further, during “purge”, as shown in FIG. 8B, the three-way switching valves 62 to 64 are switched, the on-off valve 65 is opened, and the purge pump 35 is stopped. Thereby, the flow of the atmosphere from the atmosphere line 32 to the atmosphere port 25 of the canister 21 is allowed, and the purge of vapor from the purge port 24 of the canister 21 to the intake passage 2 is allowed.

  Further, during “purge assist”, as shown in FIG. 8C, the three-way switching valves 62 to 64 are switched, the open / close valve 65 is closed, and the purge pump 35 operates normally. As a result, atmospheric flow from the atmospheric line 32 to the atmospheric port 25 of the canister 21 is allowed, and vapor purge from the purge port 24 of the canister 21 to the intake passage 2 via the purge pump 35 is allowed. At this time, negative pressure by the purge pump 35 is applied to the canister 21, and the vapor adsorbed on the canister 21 is sucked into the purge line 29, discharged from the purge pump 35, and purged to the intake passage 2.

  Furthermore, during “leakage failure diagnosis”, as shown in FIG. 8D, the three-way switching valves 62 to 64 are switched, the on-off valve 65 is closed, and the purge pump 35 operates normally. As a result, a negative pressure is applied to the blocked vapor flow path by the purge pump 35, and thereafter, a pressure change (pressure difference) in the vapor flow path is calculated by the ECU J50, and whether there is a leakage failure based on the calculation result. Determined.

  Therefore, in this embodiment as well, it is possible to perform the normal vapor purge, the vapor purge assist, and the leakage failure diagnosis by the “internal pressure monitoring method” as described above, and the same effects as the first embodiment can be obtained. Obtainable. In addition, in this embodiment, the pump assembly 61 is provided in the middle of the purge line 29 corresponding to the purge port 24 of the canister 21, and the purge pump 35 functions as a negative pressure pump during the purge assist. Thus, the vapor is sucked out of the canister 21 by negative pressure and pushed into the intake passage 2, so that the purge assist response can be improved.

[Fifth Embodiment]
Next, a fifth embodiment that embodies the evaporated fuel processing apparatus of the present invention will be described in detail with reference to the drawings.

  This embodiment differs from the fourth embodiment in the configuration and method relating to leakage fault diagnosis. As shown in FIGS. 9A to 9E, in this embodiment, a bypass passage 69 is provided between the atmospheric port 25 of the canister 21 and the first and third three-way switching valves 62 and 64. An orifice hole 70 having a diameter of 0.5 is provided in the passage 69. In this embodiment, the “reference method” is adopted as a leakage failure diagnosis method, and the bypass passage 69 and the orifice hole 70 are used to detect “reference pressure” described later. The orifice hole 70 assumes a leakage failure due to a hole of φ0.5.

  In this embodiment, as can be seen by comparing FIGS. 9A to 9C with FIGS. 8A to 8C, “parking, refueling”, “purge”, and “purge assist”. The switching state of each of the three-way switching valves 62 to 64 and the opening / closing state of the opening / closing valve 65 are the same as those of the fourth embodiment. In this embodiment, the switching of the three-way switching valves 62 to 64 and the opening / closing of the opening / closing valve 65 are different from those of the fourth embodiment in leak diagnosis.

  In the “reference method”, first, as shown in FIG. 9 (d), the three-way switching valves 62 to 64 are switched, and the purge pump 35 is operated with the on-off valve 65 closed, whereby the bypass passage 69 is opened. Give negative pressure. At this time, the pressure detected by the pressure sensor 44 is detected as a reference pressure assuming a leakage failure due to the orifice hole 70.

  Thereafter, as shown in FIG. 9 (e), the three-way switching valves 62 to 64 are switched and the opening / closing valve 65 is closed to close the vapor flow path including the canister 21 from the atmospheric line 32 to the purge line 29. By operating the purge pump 35 in this state, a negative pressure is applied by the purge pump 35 to the closed vapor flow path (closed space). At this time, the pressure detected by the pressure sensor 44 is compared with the above-described reference pressure to determine whether there is a leakage failure.

  Therefore, in this embodiment, the same operational effects as in the fourth embodiment can be obtained except for the difference in the leakage failure diagnosis method.

[Sixth Embodiment]
Next, a sixth embodiment in which the fuel vapor processing apparatus of the present invention is embodied will be described in detail with reference to the drawings.

  FIG. 10 is a schematic configuration diagram showing the engine system of this embodiment. In this embodiment, the purge line 29 is provided on the downstream side of the plurality of branch passages 29a and 29b so as to communicate with the intake passage 2, and the purge control valve 30A is provided in each of the plurality of branch passages 29a and 29b. , 30B is different from the fourth and fifth embodiments in that it is provided. More specifically, the purge line 29 branches into two parts, a first branch path 29a and a second branch path 29b, on the downstream side, and one of the first branch paths 29a is on the downstream side of the throttle valve 11. The other second branch passage 29 b is provided in communication with the intake passage 2 on the upstream side of the throttle valve 11. The first branch path 29a is provided with a first purge control valve 30A, and the second branch path 29b is provided with a second purge control valve 30B. The ECU 50 controls the purge control valves 30A and 30B. In this embodiment, the second purge control valve 30B can flow a larger amount of vapor than the first purge control valve 30A. For example, the maximum flow rate of the second purge control valve 30B can be set to about 6 times the maximum flow rate of the first purge control valve 30A.

  The difference in the contents of purge control between this embodiment and the fourth embodiment is the same as the difference between the first embodiment and the third embodiment described in the third embodiment. Omitted. Therefore, also in this embodiment, it is possible to obtain the same effects as described in the third embodiment.

[Seventh Embodiment]
Next, a seventh embodiment that embodies the fuel vapor processing apparatus of the present invention will be described in detail with reference to the drawings.

  FIG. 11 is a schematic configuration diagram showing the engine system of this embodiment. This embodiment is different from the first and fourth embodiments in the configuration and arrangement of the pump assembly 71. That is, in this embodiment, the purge pump 35 is included, but the pump assembly 71 is provided in the vapor line 26 and the atmospheric line 32 corresponding to the vapor port 23 and the atmospheric port 25 of the canister 21.

  The pump assembly 71 of this embodiment includes a purge pump 35, three three-way switching valves 72, 73, 74, a pressure sensor 44, a relief valve 37, and one on-off valve 75. 37, 44, 72 to 75 are modularized. The three three-way switching valves 72 to 74 and the one on-off valve 75 correspond to the flow path switching means of the present invention. The purge pump 35 is provided between the canister 21 and the atmospheric line 32 in order to apply pressure to the canister 21 through the vapor line 26, the vapor control valve 27 and the vapor port 23. That is, in the middle of the vapor line 26, the first and second three-way switching valves 72 and 73 are provided in series, and the on-off valve 75 is provided therebetween. The third three-way switching valve 74 is provided in the middle of the atmospheric line 32. The first and second ports of the first and second three-way switching valves 72 and 73 communicate with the vapor line 26, respectively. A third port of the first three-way switching valve 72 communicates with the atmospheric line 32 via a pipe 76a. The third port of the second three-way switching valve 73 communicates with the atmospheric line 32 via the pump flow path 77. The purge pump 35 is provided in the middle of the pump flow path 77. The first and second ports of the third three-way switching valve 74 communicate with the atmospheric line 32, respectively. The third port of the third three-way switching valve 74 communicates with the pump flow path 77 and the atmospheric line 32 through a bifurcated pipe 76b. The pressure sensor 44 is provided so as to detect the pressure of the pipe 76b. The relief valve 37 is provided in a pipe 76 c that communicates between the pump flow path 77 on the discharge side of the purge pump 35 and the atmosphere line 32. The relief valve 37 allows the air flow from the pump flow path 77 to the atmospheric line 32 and blocks the reverse flow. The parts 35, 37, 44, 72 to 75 described above are electrically connected to the ECU 50, and the purge pump 35, the three-way switching valves 72 to 74, and the on-off valve 75 are controlled by the ECU 50. Yes.

  Next, the control of each of 35, 37, 44, 72 to 75 constituting the above-described pump assembly 71 will be described with reference to FIGS. FIGS. 12A to 12D are similar to FIGS. 4A to 4D related to the “internal pressure monitoring method” already described. In this embodiment, at the time of “parking and refueling”, as shown in FIG. 12A, the three-way switching valves 72 to 74 are switched, the on-off valve 75 is opened, and the purge pump 35 is stopped. Yes. Thereby, the flow of air from the atmospheric port 25 of the canister 21 to the atmospheric line 32 is allowed, and the flow of vapor from the fuel tank 5 to the vapor port 23 of the canister 21 through the vapor line 26 is allowed.

  Further, during “purge”, as shown in FIG. 12B, the three-way switching valves 72 to 74 are switched, the on-off valve 75 is closed, and the purge pump 35 is stopped. Thereby, the flow of the atmosphere from the atmosphere line 32 to the atmosphere port 25 of the canister 21 is allowed, and the purge of vapor from the purge port 24 of the canister 21 to the intake passage 2 is allowed.

  Further, during “purge assist”, as shown in FIG. 12C, the three-way switching valves 72 to 74 are switched, the on-off valve 75 is closed, and the purge pump 35 operates normally. As a result, atmospheric flow from the atmospheric line 32 to the atmospheric port 25 of the canister 21 via the pump flow path 77 is allowed, and vapor purge from the purge port 24 of the canister 21 to the intake passage 2 through the purge line 29 is allowed. Is done. At this time, positive pressure from the purge pump 35 is applied to the canister 21, and the vapor adsorbed on the canister 21 is pushed out to the purge line 29 and is forcibly purged into the intake passage 2.

  Furthermore, during “leakage failure diagnosis”, as shown in FIG. 12D, the three-way switching valves 72 to 74 are switched, the on-off valve 75 is opened, and the purge pump 35 is reversely operated. As a result, a negative pressure is applied to the blocked vapor flow path by the purge pump 35, and thereafter, a pressure change (pressure difference) in the vapor flow path is calculated by the ECU J50, and whether there is a leakage failure based on the calculation result. Determined.

  Therefore, in this embodiment as well, it is possible to perform the normal vapor purge, the vapor purge assist, and the leakage failure diagnosis by the “internal pressure monitoring method” as described above, and the same effects as the first embodiment can be obtained. Obtainable. In addition, in this embodiment, the pump assembly 71 is provided in the middle of the vapor line 26 corresponding to the vapor port 23 of the canister 21, and the purge pump 35 functions as a positive pressure pump during purge assist. The atmosphere is pushed into the canister 21 with positive pressure. For this reason, the vapor adsorbed by the canister 21 can be pushed out from the canister 21 to the intake passage 2 by positive pressure, and the vapor adsorption capacity of the canister 21 can be restored to a state close to the initial state.

[Eighth Embodiment]
Next, an eighth embodiment that embodies the fuel vapor processing apparatus of the present invention will be described in detail with reference to the drawings.

  This embodiment differs from the seventh embodiment in the configuration and method relating to leakage fault diagnosis. As shown in FIGS. 13A to 13E, in this embodiment, a bypass passage 79 is provided between the pipe 76b provided with the pressure sensor 44 and the atmospheric line 32, and φ0.5 is provided in the passage 79. Orifice hole 80 is provided. In this embodiment, a “reference method” is adopted as a leakage failure diagnosis method, and the bypass passage 79 and the orifice hole 80 are used to detect a “reference pressure” to be described later. The orifice hole 80 assumes a leakage failure due to a hole of φ0.5.

  In this embodiment, as can be seen by comparing FIGS. 13A to 13C with FIGS. 12A to 12C, “parking, refueling”, “purge”, and “purge assist”. The switching states of the three-way switching valves 72 to 74 and the opening / closing state of the opening / closing valve 75 are the same as those of the seventh embodiment. In this embodiment, when diagnosing leakage failure, the switching of the three-way switching valves 72 to 74 and the opening / closing of the on-off valve 75 are different from those of the seventh embodiment.

  In the “reference method”, first, as shown in FIG. 13D, the three-way switching valves 72 to 74 are switched, and the purge pump 35 is reversely operated with the on-off valve 75 closed, thereby bypassing the bypass passage 79. Apply negative pressure to At this time, the pressure detected by the pressure sensor 44 is detected as a reference pressure assuming a leakage failure due to the orifice hole 80.

  Thereafter, as shown in FIG. 13 (e), the three-way switching valves 72 to 74 are switched and the on-off valve 75 is opened to close the vapor flow path including the canister 21 from the atmospheric line 32 to the purge line 29. In this state, the purge pump 35 is reversely operated to apply a negative pressure to the blocked vapor passage (closed space) by the purge pump 35. At this time, the pressure detected by the pressure sensor 44 is compared with the above-described reference pressure to determine whether there is a leakage failure.

  Therefore, in this embodiment, the same operational effects as those of the seventh embodiment can be obtained except for the difference in the leakage failure diagnosis method.

[Ninth Embodiment]
Next, a ninth embodiment embodying the fuel vapor processing apparatus of the present invention will be described in detail with reference to the drawings.

  FIG. 14 is a schematic configuration diagram showing the engine system of this embodiment. The structural difference concerning the purge line 29 between the ninth embodiment and the seventh embodiment is the same as the structural difference between the fourth embodiment and the sixth embodiment.

  The difference in the contents of purge control between this embodiment and the seventh embodiment is the same as the difference between the first embodiment and the third embodiment described in the third embodiment. Omitted. Therefore, also in this embodiment, it is possible to obtain the same effects as described in the third embodiment.

  The present invention is not limited to the above-described embodiments, and can be implemented as follows without departing from the spirit of the invention.

  (1) In the first embodiment, the purge pump 35 having the functions of a positive pressure pump and a negative pressure pump functions as a positive pressure pump for purge assist, and functions as a negative pressure pump for leak failure diagnosis. It was configured to make it. On the other hand, as the first case, depending on the difference in the arrangement of the purge pump provided corresponding to the atmospheric port, vapor port or purge port of the canister and the difference in the configuration of the flow path switching means for switching the air flow path A purge pump having both a positive pressure pump and a negative pressure pump function as a positive pressure pump for purge assist, function as a positive pressure pump for leakage failure diagnosis, It may be configured to function as a positive pressure pump for assisting and to function as a positive pressure pump and a negative pressure pump for leakage failure diagnosis. In the first case, purge assist by applying positive pressure and diagnosis of leakage failure by applying positive pressure can be performed by one purge pump. In the second case, purge assist by applying a positive pressure and leakage failure diagnosis by applying a positive pressure and a negative pressure can be performed by a single purge pump.

  (2) In the seventh to ninth embodiments, the pump assembly 71 including the purge pump 35, the three three-way switching valves 72, 73, 74, the pressure sensor 44, the relief valve 37, and the one on-off valve 75 is provided as a fuel tank. Therefore, it is conceivable that the pump assembly 71 is provided integrally with the fuel tank 5. Therefore, when the pump assembly is provided in the fuel tank, or when the pump assembly is not employed, at least flow switching means such as a purge pump and a switching valve may be provided in the fuel tank. In these cases, at least the purge pump and the flow path switching means can be provided relatively easily in the fuel tank, and the mounting space is omitted accordingly. For this reason, the purge pump and the flow path switching means can be protected in the fuel tank, and noise caused by the operating noise of the purge pump or the like can be suppressed.

  (3) In the third, sixth and ninth embodiments, the purge line 29 is branched into two branch paths 29a and 29b, and purge control valves 30A and 30B are provided in the branch paths 29a and 29b, respectively. The purge line may be branched into three or more branch paths, and a purge control valve may be provided in each branch path.

The schematic block diagram which shows an engine system and a fuel vapor processing apparatus. The flowchart which shows a purge control program. The flowchart which shows a leakage failure diagnostic control program. (A)-(d) is explanatory drawing which shows operation | movement of a pump assembly component. (A)-(e) is explanatory drawing which shows operation | movement of a pump assembly component. The schematic block diagram which shows an engine system and a fuel vapor processing apparatus. The schematic block diagram which shows an engine system and a fuel vapor processing apparatus. (A)-(d) is explanatory drawing which shows operation | movement of a pump assembly component. (A)-(e) is explanatory drawing which shows operation | movement of a pump assembly component. The schematic block diagram which shows an engine system and a fuel vapor processing apparatus. The schematic block diagram which shows an engine system and a fuel vapor processing apparatus. (A)-(d) is explanatory drawing which shows operation | movement of a pump assembly component. (A)-(e) is explanatory drawing which shows operation | movement of a pump assembly component. The schematic block diagram which shows an engine system and a fuel vapor processing apparatus.

Explanation of symbols

1 engine (internal combustion engine)
2 Intake passage 5 Fuel tank 11 Throttle valve 21 Canister 23 Vapor port (evaporated fuel port)
24 Purge port 25 Air port 29 Purge line (purge passage)
29a First branch path 29b Second branch path 30 Purge control valve 30A First purge control valve 30B Second purge control valve 32 Atmospheric line (atmospheric path)
35 Purge pump 36 Three-way switching valve (flow path switching means)
44 pressure sensor 50 ECU (processing control means, blockage control means, failure determination means)
62 First three-way switching valve (flow path switching means)
63 Second three-way switching valve (flow path switching means)
64 Third three-way switching valve (flow path switching means)
65 On-off valve (flow path switching means)
72 First three-way switching valve (flow path switching means)
73 Second three-way switching valve (flow path switching means)
74 Third three-way switching valve (flow path switching means)
75 On-off valve (channel switching means)

Claims (16)

A fuel tank for storing fuel;
An atmospheric passage provided for venting the fuel tank;
A canister provided between the fuel tank and the atmospheric passage for adsorbing the evaporated fuel generated in the fuel tank;
A purge pump provided between the canister and the atmospheric passage;
A flow path switching means for switching an air flow path between the canister, the purge pump, and the atmospheric passage;
A purge passage for purging the evaporated fuel adsorbed by the canister to the intake passage of the internal combustion engine;
A purge control valve provided in the purge passage for controlling the purge flow rate of the evaporated fuel;
The purge control valve is controlled to purge the evaporated fuel from the canister to the intake passage via the purge passage, and from the purge pump by the flow path switching means to assist the purge as necessary. In the evaporative fuel processing apparatus provided with processing control means for switching the air flow path to the canister and operating the purge pump,
In order to block the evaporated fuel flow path including the canister from the atmospheric path to the purge path, a closing control means for closing the atmospheric path by the flow path switching means and closing the purge path by the purge control valve;
A pressure sensor for detecting a pressure in the closed evaporated fuel flow path;
The purge pump is operated to apply pressure to the closed evaporated fuel flow path, and after applying pressure to the evaporated fuel flow path, a pressure change is calculated based on a detection result of the pressure sensor, and the pressure change And a failure determining means for determining a leakage failure in the evaporated fuel flow path based on the above. The processing control means performs control for assisting the purge during operation of the internal combustion engine, and the failure determination means executes a leakage failure determination when the internal combustion engine is stopped. The evaporative fuel processing apparatus according to 1. The purge pump has a function of a positive pressure pump and a function of a negative pressure pump, the processing control means causes the purge pump to function as the positive pressure pump in order to assist the purge, and the failure determination means includes: The evaporative fuel processing apparatus according to claim 2, wherein the purge pump functions as the negative pressure pump in order to determine the leakage failure. The purge pump has a function of a positive pressure pump and a function of a negative pressure pump, the processing control means causes the purge pump to function as the positive pressure pump in order to assist the purge, and the failure determination means includes: The evaporative fuel processing apparatus according to claim 2, wherein the purge pump functions as the positive pressure pump in order to determine the leakage failure. The purge pump has a function of a positive pressure pump and a function of a negative pressure pump, the processing control means causes the purge pump to function as the positive pressure pump in order to assist the purge, and the failure determination means includes: 3. The evaporative fuel processing apparatus according to claim 2, wherein the purge pump functions as the positive pressure pump and the negative pressure pump in order to determine the leakage failure. The purge pump includes an operation blade and a motor that rotates the operation blade, and the processing control unit and the failure determination unit selectively change the rotation direction of the motor of the purge pump to selectively perform the purge. 6. The evaporative fuel processing apparatus according to claim 3, wherein a pump selectively functions as the positive pressure pump or the negative pressure pump. The evaporated fuel processing apparatus according to any one of claims 1 to 6, wherein the canister includes an atmospheric port communicating with the atmospheric passage, and the purge pump is provided corresponding to the atmospheric port. The evaporated fuel processing apparatus according to claim 1, wherein the canister includes a purge port that communicates with the purge passage, and the purge pump is provided corresponding to the purge port. The evaporated fuel processing apparatus according to claim 1, wherein the canister includes an evaporated fuel port communicating with the fuel tank, and the purge pump is provided corresponding to the evaporated fuel port. . The purge passage is branched into a plurality of branch passages on the downstream side of the purge passage and communicated with the intake passage, and a purge control valve is provided in each of the plurality of branch passages. The evaporative fuel processing apparatus of description. A throttle valve is provided in the intake passage, and the purge passage is branched into two branch passages on the downstream side, and one branch passage is provided in communication with the intake passage on the upstream side of the throttle valve. 11. The evaporative fuel processing apparatus according to claim 10, wherein the other branch path is provided in communication with the intake passage on the downstream side of the throttle valve. 9. The purge passage is branched into a plurality of branch passages on the downstream side thereof, is provided in communication with the intake passage, and a purge control valve is provided in each of the plurality of branch passages. The evaporative fuel processing apparatus of description. A throttle valve is provided in the intake passage, and the purge passage is branched into two branch passages on the downstream side, and one branch passage is provided in communication with the intake passage on the upstream side of the throttle valve. The evaporated fuel processing apparatus according to claim 12, wherein the other branch passage is provided in communication with the intake passage on the downstream side of the throttle valve. 2. The purge passage according to claim 1, wherein the purge passage is branched into a plurality of branch passages downstream from the purge passage and communicated with the intake passage, and the purge control valve is provided in each of the plurality of branch passages. The evaporative fuel processing apparatus of Claim 9. A throttle valve is provided in the intake passage, and the purge passage is branched into two branch passages on the downstream side, and one branch passage is provided in communication with the intake passage on the upstream side of the throttle valve. 15. The evaporative fuel processing apparatus according to claim 14, wherein the other branch passage is provided in communication with the intake passage on the downstream side of the throttle valve. The evaporated fuel processing apparatus according to claim 1, wherein at least the purge pump and the flow path switching unit are provided in the fuel tank.

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