JP2005282502A - Evaporated fuel treating device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce accumulation of evaporated fuel in a canister by using recovery capacity to the maximum when evaporated fuel in fueling can be recovered by a fueling machine side. <P>SOLUTION: This evaporated fuel handling device for an internal combustion engine is constructed to determine whether a fueling machine used for fueling is a specific fueling machine fueling while recovering evaporated fuel in a fuel tank at a time of fueling to the fuel tank. As a result of determination, if the fueling machine is not the specific fueling machine, collection of evaporated fuel by the canister is permitted. On the other hand, if it is determined that the fueling machine is the specific fueling machine, collection of evaporated fuel by the canister is prohibited and evaporated fuel in the fuel tank is wholly collected by the specific fueling machine. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an evaporative fuel processing apparatus for an internal combustion engine, and more particularly, to a control technique for an evaporative fuel processing apparatus corresponding to an oil supply facility for collecting evaporative fuel at the time of refueling on the facility side.

  Refueling the vehicle is performed by opening a refueling lid provided on the side surface of the vehicle, opening a refueling port, inserting a refueling gun of a refueling facility, and injecting fuel into a fuel tank. At this time, evaporated fuel is generated in the fuel tank by vaporizing the fuel. Evaporated fuel is harmful and we want to minimize its release to the atmosphere. For this reason, conventionally, various methods for preventing the release of evaporated fuel into the atmosphere have been proposed.

  One is to mount a system (ORVR system) for preventing the evaporative fuel from being released into the atmosphere. The technique disclosed in Patent Document 1 is one of them. In the technique of Patent Document 1, when a fuel supply switch is pushed by the user during refueling, first, the evaporated fuel in the fuel tank is sucked by the compressor and collected in the canister, and the pressure in the fuel tank decreases to below atmospheric pressure. After that, the refueling lid is opened. After the fueling lid is opened, when the pressure in the fuel tank exceeds the atmospheric pressure, the compressor is operated again.

In addition to the method of mounting the ORVR system on the vehicle as described above, a method of providing the fuel supply facility with a function of collecting evaporated fuel has been proposed. For example, Patent Document 2 describes that a suction duct is attached to a fuel gun, and evaporated fuel generated during fueling is sucked and collected by the suction duct.
JP-A-8-121279 JP-A-8-253039

  In a vehicle equipped with the ORVR system, the evaporated fuel collected in the canister at the time of refueling is processed until the next refueling. The evaporated fuel collected in the canister is purged from the canister by applying a negative pressure in the intake passage to the canister during operation of the internal combustion engine, and is combusted in the internal combustion engine.

  However, in a vehicle such as a hybrid vehicle where the frequency of stopping the internal combustion engine is high, there is little opportunity for purging the evaporated fuel from the canister. If there is little opportunity for purging, the amount of evaporated fuel will eventually exceed the capacity of the canister, and the possibility of being released into the atmosphere as evaporation is increased. On the other hand, if the purge amount per time is increased in order to sufficiently purge the evaporated fuel from the canister, the exhaust emission may be deteriorated. Further, if the operating time of the internal combustion engine is lengthened for purging the evaporated fuel, the fuel consumption, which is an advantage of the hybrid vehicle, is reduced. Here, a hybrid vehicle is taken as an example, but the same applies to general vehicles that want to reduce the amount of fuel vapor accumulated in the canister as much as possible. This is because when a large amount of evaporated fuel is accumulated, there is a high possibility that it will eventually exceed the capacity of the canister and be released into the atmosphere as evaporation.

  If the fuel supply facility has an evaporative fuel recovery function, it is possible to recover the evaporated fuel on the fuel supply facility side. Therefore, even if the vehicle does not have an ORVR system, it is possible to prevent the evaporative fuel from being released into the atmosphere during refueling. be able to. In a vehicle equipped with an ORVR system, it is considered that the amount of evaporated fuel accumulated in the canister can be reduced because the evaporated fuel is collected on the fuel supply facility side. However, a vehicle equipped with a conventional ORVR system may or may not have an evaporative fuel recovery function on the refueling facility side, but the evaporative fuel is always recovered by operating the ORVR system during refueling. For this reason, even when the fuel supply facility collects the evaporated fuel, the canister collects the evaporated fuel, which increases the amount of evaporated fuel stored in the canister.

  The present invention has been made to solve the above-described problems. When evaporative fuel at the time of refueling can be recovered on the refueling facility side, the evaporative fuel can be supplied to the canister by making the best use of its recovery capability. It is an object of the present invention to provide an evaporative fuel processing apparatus for an internal combustion engine that can reduce accumulation.

In order to achieve the above object, a first invention is an evaporated fuel processing apparatus for an internal combustion engine,
A fuel tank for storing fuel;
A canister connected to the fuel tank;
Determination means for determining whether or not the fueling facility used for fueling is a specific fueling facility that performs fueling while recovering the evaporated fuel in the fuel tank when fueling the fuel tank;
When the determination means determines that the fuel supply facility is not the specific fuel supply facility, the evaporated fuel in the fuel tank is collected in the canister, and the determination means determines that the fuel supply facility is the specific fuel supply facility. Control means for prohibiting the collection of evaporated fuel by the canister when
It is characterized by having.

  In a second aspect based on the first aspect, when the pressure in the fuel tank becomes equal to or higher than a predetermined value during refueling by the specific refueling facility, the control means prohibits collection of evaporated fuel by the canister. It is characterized by that.

  According to a third invention, in the first invention, the determining means determines that the fueling facility is the specific fueling facility when the pressure in the fuel tank becomes a predetermined value or less during fueling. Yes.

In a fourth aspect based on the first aspect, the determination means is provided in the vicinity of a fuel filler port of the fuel tank, and an evaporative fuel suction duct provided in the specific fueling facility is attached to the fuel filler port. Including detection means for detecting,
The determination means determines that the fuel supply facility is the specific fuel supply facility when the detection means detects the attachment of the suction duct to the fuel supply port during fueling.

According to a fifth invention, in the first invention, control constant determining means for determining a control constant of the internal combustion engine based on an accumulated amount of evaporated fuel in the canister;
A collection amount calculating means for calculating a collection amount of the evaporated fuel of the canister at the time of refueling from the refueling amount and updating the accumulated amount;
When the determination means determines that the fuel supply facility is the specific fuel supply facility, the collection amount calculation means supplies more oil than when the determination means determines that the fuel supply facility is not the specific fuel supply facility. The conversion ratio of the amount of evaporated fuel to the amount is set to be small.

  According to the first aspect of the present invention, the vaporized fuel can be accumulated in the canister by making maximum use of the vaporized fuel recovery capability of the fueling facility while always preventing the vaporized fuel from being released into the atmosphere regardless of the type of fueling facility. Can be reduced.

  Depending on the relationship between the fuel flow rate at the time of refueling and the evaporative fuel recovery speed by the specific refueling facility, there is a possibility that the outflow of gas from the fuel tank will worsen and the fuel will be difficult to enter. According to the second invention, even when fuel is supplied by a specific fueling facility, if the pressure in the fuel tank becomes high, evaporative fuel collection by the canister is lifted. can do.

  Moreover, even if it is a specific refueling facility, it is possible that the evaporated fuel cannot be recovered due to a failure. However, according to the third aspect, when the pressure in the fuel tank does not decrease, the evaporated fuel is collected by the canister. The evaporated fuel is prevented from being released to the atmosphere. Further, according to the third aspect of the invention, there is an advantage that if there is only a pressure sensor in the fuel tank, the specific fueling facility can be easily determined from the detection signal.

  Further, even if the specific fueling facility is used, when the suction duct for the evaporated fuel is not accurately attached to the fuel filler port, there is a high possibility that the evaporated fuel at the time of fueling cannot be recovered. According to the fourth invention, since the evaporated fuel is collected by the canister when the evaporated fuel suction duct is not accurately attached to the fuel filler port, the evaporated fuel is prevented from being released to the atmosphere. The

  Some control constants of the internal combustion engine are determined on the basis of the accumulated amount of evaporated fuel in the canister, such as a target purge rate. Since such a control constant affects the fuel consumption and exhaust emission of the internal combustion engine, it is desirable that the accumulated amount of evaporated fuel in the canister, which is the basis for the determination, be accurately estimated. According to the fifth aspect of the present invention, the accumulation amount of the evaporated fuel can be accurately estimated by changing the setting of the conversion ratio of the collected amount with respect to the refueling amount according to the type of the refueling facility. It becomes possible to determine the control constant of the internal combustion engine based on the quantity.

Embodiment 1 FIG.
Hereinafter, the first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

[Description of device configuration]
FIG. 1A is a diagram for explaining the overall configuration of an internal combustion engine in which the evaporated fuel processing apparatus according to the first embodiment of the present invention is incorporated. As shown in FIG. 1A, the internal combustion engine includes a fuel tank 10. The fuel tank 10 is provided with a tank internal pressure sensor 12 for measuring the tank internal pressure Pt. The tank internal pressure sensor 12 is a sensor that detects a tank internal pressure Pt as a relative pressure with respect to the atmospheric pressure and generates an output corresponding to the detected value. A liquid level sensor 14 for detecting the liquid level of the fuel is disposed inside the fuel tank 10.

  A vapor passage 20 is connected to the fuel tank 10 via ROV (Roll Over Valve) 16 and 18. The vapor passage 20 includes a blocking valve unit 24 in the middle thereof, and communicates with the canister 26 at the end thereof. The block valve unit 24 includes a block valve 28 and a relief valve 30. The block valve 28 is a normally closed electromagnetic valve that closes in a non-energized state and opens when a drive signal is supplied from the outside. The relief valve 30 includes a forward relief valve that opens when the pressure on the fuel tank 10 side is sufficiently higher than the pressure on the canister 26 side, and a reverse relief valve that opens in the opposite case. This is a mechanical two-way check valve.

  The canister 26 includes a purge hole 32. A purge passage 34 communicates with the purge hole 32. The purge passage 34 is provided with a purge valve (VSV: Vacuum Switching Valve) 36 in the middle thereof, and communicates with an intake passage 38 of the internal combustion engine at an end thereof. An air filter 40, an air flow meter 42, a throttle valve 44, and the like are provided in the intake passage 38 of the internal combustion engine. The purge passage 34 communicates with the intake passage 38 downstream of the throttle valve 44.

  The inside of the canister 26 is filled with activated carbon. The evaporated fuel flowing in through the vapor passage 20 is adsorbed by the activated carbon. The canister 26 also has an air hole 50. An atmospheric passage 54 communicates with the atmospheric hole 50 via a negative pressure pump module 52. The air passage 54 includes an air filter 56 in the middle thereof. The end of the atmospheric passage 54 is open to the atmosphere in the vicinity of the fuel filler port 58 of the fuel tank 10.

  The internal combustion engine is provided with an ECU (Electronic Control Unit) 60 as a control device for comprehensively controlling the operation of the entire internal combustion engine. A lid switch 62 and a lid opener 64 are connected to the ECU 60 together with the tank internal pressure sensor 12, the sealing valve 28, or the negative pressure pump module 52 described above. The ECU 60 has a built-in soak timer for counting the elapsed time while the vehicle is parked. The lid opener 64 is connected to a lid manual opening / closing device 66 by a wire.

  The lid opener 64 is a lock mechanism for an oil supply lid (vehicle body lid) 68 that covers the oil supply port 58, and when the permission signal for permitting the opening of the oil supply lid 68 is supplied from the ECU 60, or to the lid manual opening / closing device 66. On the other hand, when a predetermined opening operation is performed, the lock of the fuel supply lid 68 is released. When the lock of the fuel supply lid 68 is released and the fuel supply lid 68 is opened, the user can remove the tank cap 59 from the fuel supply port 58 and supply fuel to the fuel tank 10. The lid switch 62 connected to the ECU 60 is a switch for sending a request signal for requesting the ECU 60 to open the fuel supply lid 68.

  FIG. 1B is an enlarged view for explaining details of the negative pressure pump module 52 shown in FIG. The negative pressure pump module 52 includes a canister-side passage 70 that communicates with the atmosphere hole 50 of the canister 26 and an atmosphere-side passage 72 that communicates with the atmosphere. A pump passage 78 including a pump 74 and a check valve 76 communicates with the atmosphere side passage 72. The negative pressure pump module 52 also includes a switching valve 80 and a bypass passage 82. The switching valve 80 communicates the canister-side passage 70 with the atmosphere-side passage 72 in a non-energized state (OFF state), and the canister-side passage 70 is connected to the pump passage in a state where an external drive signal is supplied (ON state). 78. The bypass passage 82 is a passage that connects the canister-side passage 70 and the pump passage 78, and includes a 0.5 mm diameter reference orifice 84 in the middle thereof. The negative pressure pump module 52 further incorporates a pump module pressure sensor 86. The pump module pressure sensor 86 can detect the pressure inside the pump passage 78 on the switching valve 80 side of the check valve 76.

[Description of operation]
Next, the operation of the evaporated fuel processing apparatus according to this embodiment will be described.
(1) During parking In principle, the fuel vapor processing apparatus according to the present embodiment maintains the closing valve 28 in a closed state while the vehicle is parked. When the blocking valve 28 is closed, the fuel tank 10 is cut off from the canister 26 as long as the relief valve 30 is closed. Therefore, in the internal combustion engine according to the present embodiment, the evaporated fuel is not newly adsorbed by the canister 26 while the vehicle is parked unless the tank internal pressure Pt exceeds the positive valve opening pressure of the relief valve 30. Further, as long as the tank internal pressure Pt does not fall below the reverse valve opening pressure of the relief valve 30, air is not sucked into the fuel tank 10 while the vehicle is parked.

(2) During traveling When the vehicle is traveling, control for purging the evaporated fuel adsorbed by the canister 26 is executed when a predetermined purge condition is satisfied. Specifically, in this control, the purge valve 36 is appropriately duty-driven while the switching valve 80 is turned OFF and the atmospheric hole of the canister 26 is opened to the atmosphere. When the purge valve 36 is driven with a duty, the intake negative pressure of the internal combustion engine 10 is guided to the purge hole 32 of the canister 26. As a result, the evaporated fuel in the canister 26 is discharged into the intake passage 38 together with the air sucked from the air hole 50.

  Further, during the traveling of the vehicle, the block valve 28 is opened so that the tank internal pressure Pt is maintained in the vicinity of the atmospheric pressure for the purpose of shortening the pressure release time before refueling. However, the valve opening is performed only during the purge of the evaporated fuel, that is, only when the intake negative pressure is introduced into the purge hole 32 of the canister 26. Under the situation where the intake negative pressure is guided to the purge hole 32, the evaporated fuel that flows into the canister 26 from the fuel tank 10 flows out of the purge hole 32 without entering deeply into the canister 26, and is then discharged into the intake passage 38. The Therefore, a large amount of evaporated fuel is not newly adsorbed by the canister 26 while the vehicle is running.

(3) At the time of refueling The operation at the time of refueling of the evaporative fuel processing apparatus according to the present embodiment will be described with reference to the flowchart of FIG. As described below, the opening / closing control of the blocking valve 28 is executed during refueling, and the control routine of the opening / closing control of the closing valve 28 executed by the ECU 60 is shown in the flowchart of FIG. The ECU 60 executes the routine shown in FIG. 2 at a predetermined cycle.

  In the routine shown in FIG. 2, first, it is determined whether or not there is a refueling request from the user (step 100). When the user operates the lid switch 62, a request signal for requesting the ECU 60 to open the fuel supply lid 68 is supplied from the lid switch 6. The ECU 60 receives the request signal and determines that there has been a refueling request from the user.

  When there is a refueling request from the user, the ECU 60 supplies a drive signal to the closing valve 28 to open the closing valve 28 (step 102). At this time, if the tank internal pressure Pt is higher than the atmospheric pressure, the closed valve 28 is opened and the evaporated fuel is released from the fuel tank 10 at the same time. As a result, the tank internal pressure Pt is reduced to near atmospheric pressure. The evaporated fuel discharged from the fuel tank 10 flows into the canister 26 and is adsorbed by the activated carbon inside. In step 104, it is determined whether or not the tank internal pressure Pt has been reduced. In step 104, the current tank internal pressure Pt is compared with a predetermined pressure reduction completion determination value, and if the tank internal pressure Pt is equal to or lower than the pressure reduction completion determination value, it is determined that pressure reduction has been completed.

  When the pressure reduction of the tank internal pressure Pt is completed, the valve opening control of the oil supply lid 68 is executed next. ECU 60 issues a permission signal to permit opening of refueling lid 68 to lid opener 64. In response to the permission signal, the lid opener 64 unlocks the fuel supply lid 68 and opens the fuel supply lid 68 (step 106).

  When the fuel supply lid 68 is opened, the tank cap 59 is then opened by the user, and then fuel supply from the fuel supply facility is started. Since the tank internal pressure Pt is reduced to near atmospheric pressure before the tank cap 59 is opened by the processing in steps 102 and 104, the evaporated fuel is released from the fuel filler port 58 to the atmosphere as the tank cap 59 is opened. There is nothing.

  After the start of refueling, the ECU 60 determines whether or not the refueling facility used for refueling is a refueling facility (hereinafter referred to as a specific refueling facility) that refuels while collecting the evaporated fuel in the fuel tank 10 (step 108). . The specific fueling facility is provided with a suction duct in the fueling gun, and simultaneously with the fueling of the fuel tank 10 by the fueling gun, the evaporated fuel in the fuel tank 10 is sucked and collected by the suction duct. Whether or not the fueling facility is the specific fueling facility can be determined from a change in the tank internal pressure Pt during fueling. At the time of refueling, the tank cap 59 is removed from the refueling port 58 so that the fuel tank 10 communicates with the atmosphere, and the tank internal pressure Pt of the fuel tank 10 becomes atmospheric pressure. However, when the fuel supply facility is the specific fuel supply facility, the tank internal pressure Pt of the fuel tank 10 becomes negative by sucking the evaporated fuel inside by the suction duct. Therefore, by detecting the tank internal pressure Pt at the time of refueling with the tank internal pressure sensor 12, it can be easily determined whether or not the refueling facility is the specific refueling facility.

  If the result of determination in step 108 is that the fueling facility is determined to be the specific fueling facility, the blockade valve 28 is closed (step 110). By closing the blocking valve 28, the communication between the fuel tank 10 and the canister 26 is blocked, and the adsorption of the evaporated fuel by the canister 26 is prohibited. Evaporated fuel generated in the fuel tank at the time of refueling is recovered by a specific refueling facility, thereby preventing release to the atmosphere.

  On the other hand, as a result of the determination in step 108, when it is determined that the fueling facility is a normal fueling facility, that is, a fueling facility having no evaporative fuel recovery function, the block valve 28 is maintained in the open state (step). 112). By opening the shut-off valve 28, the gas in the fuel tank 10 can flow out to the canister 26 through the vapor passage 20, and as a result, good oil supply is ensured. At this time, the evaporated fuel flowing out from the fuel tank 10 is adsorbed by the canister 26, so that the evaporated fuel is not released to the atmosphere.

  In step 114, it is determined whether or not refueling is completed. The end of refueling can be determined from the closing of the refueling lid 68 detected by a sensor (not shown). The blockade valve 28 is maintained in a state corresponding to the determination result of step 108 until the end of refueling, and is closed upon receiving the determination of the end of refueling (step 116).

  According to the routine described above, when the fueling facility is the specific fueling facility, the recovery capability of the evaporated fuel is utilized to the maximum to prevent the evaporated fuel from being released into the atmosphere and to the canister 26. The accumulation of evaporated fuel can be reduced. In addition, when the fuel supply facility is not a specific fuel supply facility, the evaporated fuel is collected by the canister 26, so that even in this case, the evaporated fuel can be prevented from being released into the atmosphere.

  In addition, even if it is a specific fueling facility, it is possible that evaporative fuel cannot be recovered due to a failure. However, according to the method for determining the specific fueling facility from the tank internal pressure Pt as described above, even if it is a specific fueling facility, When the tank internal pressure Pt does not decrease, it is not determined as the specific fuel supply facility. For this reason, the evaporative fuel is collected by the canister 26, and the evaporative fuel is prevented from being released to the atmosphere due to the failure of the specific fuel supply facility.

  In the above-described embodiment, the “determination means” of the first invention is realized by the execution of the process of step 108 by the ECU 60, and the “determination means” of the first invention is realized by the execution of the processes of steps 110 and 112 by the ECU 60. "Control means" is realized.

Embodiment 2.
Hereinafter, the second embodiment of the present invention will be described with reference to FIG.
The evaporated fuel processing apparatus of the present embodiment can be realized by causing the ECU 60 to execute the routine of FIG. 3 instead of the routine of FIG. 2 in the first embodiment.

  In the first embodiment described above, when the fueling facility is the specific fueling facility, the blocking valve 28 is closed. The fuel supply property to the fuel tank 10 at this time is ensured by evaporating the fuel in the fuel tank 10 by the specific fuel supply facility. However, the fuel flow rate at the time of fuel supply and the recovery rate of the fuel evaporated by the specific fuel supply facility Depending on the relationship, there is a possibility that the gas escape from the fuel tank 10 becomes worse and the fuel is difficult to enter. Therefore, in the apparatus according to the present embodiment, the following opening / closing control of the blocking valve 28 is executed at the time of refueling in order to ensure a good refueling property regardless of the type of refueling equipment.

  The flowchart of FIG. 3 shows a control routine for opening / closing control of the blocking valve 28 executed by the ECU 60 in the present embodiment. In the control routine of FIG. 3, the processing from step 200 to step 212 is the same as the processing from step 100 to step 112 in the control routine of FIG. Further, the processing of step 218 and step 220 has the same contents as the processing of step 114 and step 116 in the control routine of FIG. Here, the processing of step 214 and step 216 newly added in the present embodiment will be described.

  The process of step 214 is executed when it is determined in step 208 that the fueling facility is the specific fueling facility, and the blockade valve 28 is closed in response to the determination result. When the evaporative fuel recovery capability by the specific fuel supply facility is lower than the fuel flow rate at the time of fuel supply, the gas escape from the fuel tank 10 becomes worse and the fuel becomes difficult to enter. In step 214, it is determined whether or not the gas has escaped from the fuel tank 10. As a specific method, it is determined whether or not the tank internal pressure Pt of the fuel tank 10 is equal to or higher than a predetermined value.

  As a result of the determination in step 214, when the tank internal pressure Pt does not exceed the predetermined value, it is determined that the gas has been satisfactorily released from the fuel tank 10, and the block valve 28 is maintained in the closed state as it is.

  On the other hand, as a result of the determination in step 214, when the tank internal pressure Pt becomes equal to or higher than a predetermined value, it is determined that the outflow of gas from the fuel tank 10 has deteriorated, and similarly to the case where the fueling facility is not the specific fueling facility. The blocking valve 28 is opened (step 216). By opening the shut-off valve 28, the gas in the fuel tank 10 can flow out to the canister 26 through the vapor passage 20, and as a result, good oil supply performance is ensured.

  According to the routine described above, even when fuel is supplied by the specific fueling facility, if the tank internal pressure Pt of the fuel tank 10 increases, the collection of the evaporated fuel by the canister 26 is lifted. It is possible to improve the oil supply property.

  In the above embodiment, the function of the “control means” according to the second aspect of the present invention is realized by the execution of the processes of steps 214 and 216 by the ECU 60.

Embodiment 3.
Hereinafter, Embodiment 3 of the present invention will be described with reference to FIGS.
The evaporative fuel processing apparatus of the present embodiment can be realized by causing the ECU 60 to further execute the routines of FIGS. 4, 5, and 7 in the first or second embodiment.

  Some control constants of the internal combustion engine are determined based on the accumulated amount of evaporated fuel in the canister 26, such as a target purge rate. Since such a control constant affects the fuel consumption and exhaust emission of the internal combustion engine, it is desirable that the accumulated amount of evaporated fuel in the canister 26 which is the basis for the determination is accurately estimated. As described in the explanation of the operation of the apparatus according to the first embodiment, the apparatus of the present embodiment is configured such that the canister 26 collects only the evaporated fuel only at the time of refueling, and is accumulated in the canister 26. The evaporated fuel is purged during traveling. For this reason, it is possible to accurately estimate the accumulated amount by obtaining the amount of evaporated fuel collected during refueling and the amount of evaporated fuel purged during traveling. In the apparatus of the present embodiment, the amount of fuel vapor accumulated in the canister 26 is calculated according to the routines shown in FIGS.

  The flowcharts of FIGS. 4 and 5 show the routines for calculating the fuel vapor accumulation amount executed by the ECU 60 in the present embodiment. The calculation routine of FIG. 4 is a routine (subroutine) that is executed after refueling is completed. In this calculation routine, the accumulated amount of evaporated fuel immediately after refueling is calculated. First, in step 300, it is determined whether it is immediately after the end of refueling. The end of refueling can be determined from the closing of the refueling lid 68. The ECU 60 determines that the condition of step 300 is satisfied when a signal indicating the closing of the fuel supply lid 68 is input from a sensor (not shown), and executes the processing after step 302.

  In step 302, it is determined whether or not the fueling facility used for fueling is a specific fueling facility. For this determination, the determination result of Step 108 (Embodiment 1) or Step 208 (Embodiment 2) according to the opening / closing control routine of the blocking valve 28 executed at the time of refueling is used. The result of this determination is reflected in the calculation of the trapped amount of evaporated fuel.

  The collection amount of the evaporated fuel can be calculated based on the amount of fuel supplied to the fuel tank 10. The canister 26 collects the evaporated fuel flowing out from the fuel tank 10 through the vapor passage 20, but the amount of evaporated fuel flowing out of the fuel tank 10 is equal to the amount of fuel supplied to the fuel tank 10. Since the empty space in the fuel tank 10 is filled with the saturated vapor of fuel, the evaporated fuel having the same volume as the supplied fuel is pushed out. Therefore, if the ratio of the evaporated fuel flowing out to the canister 26 in the evaporated fuel pushed out of the fuel tank 10 by refueling is known, the amount of evaporated fuel collected can be determined from the amount of fuel supplied.

  When the fueling facility used for fueling is a normal fueling facility that is not a specific fueling facility, the evaporative fuel pushed out of the fuel tank 10 by the fueling flows out to the canister 26 by opening the block valve 28, and the canister 26. Therefore, the amount of evaporated fuel collected in this case is equal to the amount of fuel supplied. In this case, the ECU 60 sets the conversion ratio k1 of the collected amount of evaporated fuel to the amount of fuel supplied to 1 (step 304).

  On the other hand, when the refueling facility used for refueling is the specific refueling facility, the blocking valve 28 is basically closed as described in the first and second embodiments. While the sealing valve 28 is closed, the evaporated fuel is not collected by the canister 26. However, until the oil supply facility is determined as the specific oil supply facility and the blockade valve 28 is closed (Embodiments 1 and 2), and after the blockage valve 28 is opened again due to the increase in the tank internal pressure Pt (the implementation) In the form 2), a part of the evaporated fuel flows out to the canister 26 and is collected in the canister 26. In any case, when the fuel supply facility is the specific fuel supply facility, the evaporated fuel collected in the canister 26 becomes a part of the evaporated fuel flowing out of the fuel tank 10 with the fuel supply. Since it is difficult to detect the evaporated fuel that has actually flown into the canister 26, the ECU 60 substitutes the converted amount of the evaporated fuel for the collected amount of the evaporated fuel as in the case where the fueling facility is a normal fueling facility. . However, since a part of the evaporated fuel flows out to the canister 26, the amount of evaporated fuel collected by the canister 26 is smaller than the amount of fuel supplied. For this reason, when the fueling facility is the specific fueling facility, the ECU 60 sets the conversion ratio k1 of the collected amount of evaporated fuel with respect to the fueling amount to a value a (a <1) smaller than 1 (step 306). In addition, a may be a fixed value (for example, 0.5), and may be determined according to the opening time of the blocking valve 28 with respect to the refueling time.

  In step 308, the amount of evaporated fuel collected by the canister 26 (the amount collected during refueling) is calculated using the conversion ratio k 1 set in step 304 or step 304. Specifically, a value obtained by multiplying the amount of oil supplied by the conversion ratio k1 is the amount of oil collected. The fuel supply amount is calculated from the fuel level position detected by the level sensor 14 in the fuel tank 10.

  The collection amount at the time of refueling calculated in step 308 is added to the accumulated amount of evaporated fuel before refueling (accumulated amount before refueling), and the accumulated amount of evaporated fuel after refueling is newly calculated (step 310). The accumulated amount of evaporated fuel is stored in the memory of the ECU 60 and is updated each time a calculation routine of FIG. 4 or a calculation routine of FIG. 5 described later is executed. In step 310, the latest accumulated amount stored in the memory is read as the accumulated amount before refueling.

  The accumulated amount of evaporated fuel after refueling calculated by the calculation routine of FIG. 4 is reflected in the calculation routine (main routine) of FIG. The calculation routine of FIG. 5 is a routine that is executed at a predetermined cycle while the ECU 60 is activated. First, in step 400, the latest accumulation amount stored in the memory is read as the previous accumulation amount. When refueling is performed, the accumulated amount after refueling calculated in the calculation routine of FIG. 4 is read as the previous accumulated amount, and when refueling is not performed, it is calculated by the previous execution of this routine. The accumulated amount after refueling is read as the previous accumulated amount.

  Subsequently, in step 402, the purge amount from the previous execution of this routine is read. The purge amount can be obtained from the drive amount (opening degree) of the purge valve 36 and the negative pressure of the intake pipe. The purge amount is obtained every time purge control is performed, and the integrated value is stored in the memory of the ECU 36. The integrated value of the purge amount is cleared after execution of this routine, and in step 402, the latest value before clearing is read.

  In step 404, the current evaporated fuel accumulation amount is calculated from the previous accumulation amount read in step 400 and the previous purge amount read in step 402. In an apparatus that collects evaporated fuel in the canister 26 only during refueling as in the apparatus of the present embodiment, the accumulated amount of evaporated fuel in the canister 26 during traveling is uniquely determined from the purge amount. FIG. 6 is a map showing the desorption characteristics of the evaporated fuel from the canister. According to this map, if the previous accumulated amount and the purge amount from the previous execution are known, the accumulated amount of evaporated fuel at the present time is uniquely determined. The ECU 60 calculates the current accumulation amount based on the map shown in FIG.

  In the apparatus of the present embodiment, the control constant of the internal combustion engine is set based on the accumulated amount of evaporated fuel in the canister 26 calculated by the calculation routine of FIG. Hereinafter, a method for setting the target purge rate will be described as an example.

  The flowchart of FIG. 7 shows a calculation routine for calculating the purge reduction coefficient for setting the target purge rate. In the calculation routine of FIG. 7, first, in step 500, it is determined whether or not the accumulated amount of evaporated fuel in the canister 26 is equal to or less than a predetermined value. If the accumulated amount exceeds the predetermined value, the purge reduction coefficient k2 is set to 1 (step 506). The purge reduction coefficient k2 is a coefficient by which the base value of the target purge rate is multiplied. The smaller the purge reduction coefficient k2, the smaller the target purge rate is set. In this case, since the purge reduction coefficient k2 is 1, the target purge rate is set according to the base value. The base value of the target purge rate is determined based on parameters other than the accumulated amount of evaporated fuel, such as the operating state of the internal combustion engine.

  If the accumulated amount is less than or equal to the predetermined value as a result of the determination in step 500, purge control target correction is permitted (step 502), and the purge reduction coefficient k2 is set to a value b (b <1) corresponding to the accumulated amount. (Step 504). FIG. 8 is a map for determining the purge reduction coefficient k2 from the accumulated amount of evaporated fuel in the canister 26. As shown in this map, when the accumulation amount is less than or equal to a predetermined value, the purge reduction coefficient k2 is set to be small in proportion to the accumulation amount. It should be noted that the canister 26 has an accumulated amount of evaporated fuel (heel amount) that has a small influence on the evaporation emission. When the accumulated amount is equal to or less than this heel amount, the purge reduction coefficient k2 is set to the minimum value. In FIG. 8, the minimum value of the purge reduction coefficient k2 is 0. However, the minimum value may be set to a value larger than 0 so that purge is always executed even if the accumulation amount is equal to or less than the heel amount.

  The graph of FIG. 9 is a diagram specifically showing an example in which the purge reduction coefficient k2 is reflected on the target purge rate. FIG. 9 shows an example of setting the target purge rate with respect to the elapsed time from the start of the internal combustion engine. First, the base value of the target purge rate will be described. At the time of warm-up immediately after start-up, vapor concentration learning (concentration learning of evaporated fuel supplied to the internal combustion engine by purge control) is not yet completed during A / F learning. Therefore, the base value is set small. Eventually, the base value is raised as the vapor concentration learning progresses, and after the vapor concentration learning is completed, the base value is set to the maximum value.

  The target purge rate is calculated by multiplying the base value set as described above by the purge reduction coefficient k2. The target purge rate is set lower than the base value over the entire area by the correction by the purge reduction coefficient k2, and as a result, the purge amount is reduced. If the accumulated amount of evaporated fuel in the canister 26 is originally small, even if the purge amount is reduced in this way, the evaporation is not deteriorated. Furthermore, in hybrid vehicles and idling stop vehicles (vehicles equipped with an eco-run system) in which the internal combustion engine stops during operation of the vehicle, it is not necessary to move the internal combustion engine only for purge control of the canister 26, so that practical fuel consumption is improved. Can be made. Moreover, since introduction of purge gas into the internal combustion engine is a disturbance that causes deterioration of exhaust emission, reducing the purge amount is also advantageous from the viewpoint of exhaust emission.

Others.
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and modifications can be made without departing from the spirit of the present invention. For example, the following modifications may be made.

  In the above embodiment, it is determined whether or not the fueling facility used for fueling is the specific fueling facility from the change in the tank internal pressure Pt during fueling, but the determination means for the specific fueling facility is limited to this. It is not a thing. FIG. 10A and FIG. 10B are schematic views showing modified examples of the determining means. Here, a duct detection sensor 100 is provided in the vicinity of the fuel filler port 58 of the fuel tank 10. Refueling is performed by removing the tank cap 59 from the refueling port 58 and inserting the nozzle of the refueling gun into the refueling port 58. If the refueling facility is a specific refueling facility, suction is performed to cover the refueling port 58. A duct is installed. The duct detection sensor 100 is installed so as to detect the attachment of the suction duct. In this case, when the duct detection sensor 100 detects the attachment of the suction duct, the ECU 60 determines that the fueling facility is the specific fueling facility.

  Even in the case of the specific fueling facility, when the suction duct is not correctly attached to the fueling port 58, there is a possibility that the evaporated fuel at the time of fueling cannot be recovered. When the duct detection sensor 100 is used, it is not determined that the oil supply facility is the specific oil supply facility unless the suction duct is accurately attached to the oil supply port 58. Therefore, the control of the closing valve 28 similar to that of the normal oil supply facility is performed. Done. As a result, the evaporative fuel is collected by the canister 26, and the evaporative fuel is prevented from being released to the atmosphere due to poor mounting of the suction duct.

It is a figure for demonstrating the structure of the internal combustion engine in which the fuel vapor processing apparatus concerning Embodiment 1 of this invention was integrated. It is a figure for demonstrating the detailed structure of the negative pressure pump module shown in FIG. 1 (A). It is a flowchart which shows the control routine of the blocking valve performed by ECU at the time of refueling in Embodiment 1 of this invention. It is a flowchart which shows the control routine of the blocking valve performed by ECU at the time of refueling in Embodiment 2 of this invention. It is a flowchart which shows the calculation routine of the fuel vapor accumulation amount performed by ECU after refueling in Embodiment 3 of this invention. It is a flowchart which shows the main calculation routine of the fuel vapor accumulation amount performed by ECU in Embodiment 3 of this invention. It is a map which shows the detachment | desorption characteristic of the evaporative fuel from a canister. It is a flowchart which shows the calculation routine of the purge reduction coefficient performed by ECU in Embodiment 3 of this invention. 6 is a map for determining a purge reduction coefficient from the accumulated amount of evaporated fuel in a canister. It is a graph which shows the example of reflection to the target purge rate of a purge reduction coefficient. It is the schematic which shows the other structural example of the determination means which determines specific oil supply equipment. It is AA sectional drawing of FIG. 10 (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel tank 12 Tank internal pressure sensor 20 Vapor passage 26 Canister 28 Sealing valve 36 Purge valve 58 Refueling port 59 Tank cap 60 ECU (Electronic Control Unit)
68 Refueling lid 100 Duct detection sensor Pt Tank internal pressure

Claims (5)

An evaporative fuel processing apparatus for an internal combustion engine,
A fuel tank for storing fuel;
A canister connected to the fuel tank;
Determining means for determining whether or not the fueling facility used for fueling is a specific fueling facility that performs fueling while collecting the evaporated fuel in the fuel tank when fueling the fuel tank;
When the determination means determines that the fuel supply facility is not the specific fuel supply facility, the evaporated fuel in the fuel tank is collected in the canister, and the determination means determines that the fuel supply facility is the specific fuel supply facility. Control means for prohibiting the collection of evaporated fuel by the canister,
An evaporative fuel processing apparatus for an internal combustion engine, comprising:   2. The internal combustion engine according to claim 1, wherein when the pressure in the fuel tank becomes equal to or higher than a predetermined value during refueling by the specific refueling facility, the control means prohibits the collection of evaporated fuel by the canister. Evaporative fuel processing equipment.   2. The evaporative fuel processing for an internal combustion engine according to claim 1, wherein the determining means determines that the fueling facility is the specific fueling facility when the pressure in the fuel tank becomes a predetermined value or less during fueling. apparatus. The determination unit includes a detection unit that is provided in the vicinity of a fuel filler port of the fuel tank and detects attachment of the suction duct for evaporated fuel provided in the specific fueling facility to the fuel filler port,
2. The internal combustion engine according to claim 1, wherein the determination unit determines that the fuel supply facility is the specific fuel supply facility when the detection unit detects attachment of the suction duct to the fuel supply port during fueling. Evaporative fuel processing equipment for engines. Control constant determining means for determining a control constant of the internal combustion engine based on an accumulated amount of evaporated fuel in the canister;
A collection amount calculating means for calculating a collection amount of the evaporated fuel of the canister at the time of refueling from the refueling amount and updating the accumulated amount;
When the determination means determines that the fuel supply facility is the specific fuel supply facility, the collection amount calculation means supplies more oil than when the determination means determines that the fuel supply facility is not the specific fuel supply facility. 2. The evaporative fuel processing apparatus for an internal combustion engine according to claim 1, wherein the conversion ratio of the collected amount of evaporative fuel to the amount is set small.

Images