JP2010270619A - Evaporated fuel treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely execute a purge process of a canister, without using, for example the negative pressure in an internal combustion engine. <P>SOLUTION: An evaporated fuel treatment device includes an air conditioning system (500) having a refrigerant circulation circuit (500a) circulating refrigerant, a canister (400) adsorbing evaporated fuel produced in a fuel tank (300) storing fuel, refrigerant introduction means (610, 611) introducing refrigerant to the canister from the refrigerant circulation circuit, a refrigerant return means (620) returning the refrigerant introduced to the canister by the refrigerant introduction means together with the evaporated fuel removed from the canister by the introduced refrigerant to the refrigerant circulation circuit as mixture, and fuel recirculation means (630, 640) liquefying the evaporated fuel contained in the mixture returned to the refrigerant circulation circuit by the refrigerant return means and recirculating the same to the fuel tank. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technical field of an evaporative fuel processing apparatus for processing evaporative fuel.

  2. Description of the Related Art As an evaporative fuel processing apparatus for processing evaporative fuel generated in a fuel tank of an internal combustion engine (hereinafter appropriately referred to as “vapor”), an apparatus for connecting a canister containing an adsorbent such as activated carbon to the fuel tank is known. (For example, see Patent Documents 1 to 3). For example, Patent Document 1 discloses a device that reduces the amount of evaporated fuel flowing into a canister by cooling the evaporated fuel generated in the fuel tank with a cooler and liquefying it back to the fuel tank. Patent Document 2 discloses an apparatus for rapidly cooling and liquefying by evaporating rapidly after evaporating fuel derived from a canister is pressurized. Patent Document 3 discloses a device that liquefies evaporated fuel with cold air obtained by an air conditioning system circuit and returns it to the fuel tank again.

  When the canister as described above is used, there is a limit to the adsorption capacity of the adsorbent, and thus a purge process is required to release vapor from the adsorbent before the adsorbent is saturated. The purge process is generally performed by taking the atmosphere into the canister, releasing vapor from the adsorbent, and introducing the purge gas containing the released vapor into the intake system using the negative pressure of the internal combustion engine. .

Japanese Patent Laid-Open No. 6-147029 JP 2002-122047 A Japanese Unexamined Patent Publication No. 63-212756

  In a hybrid vehicle (HV: Hybrid Vehicle) including an internal combustion engine and a motor as drive sources, it is possible to perform EV (Electric Vehicle) travel using only the drive force of the motor, and the start frequency of the internal combustion engine tends to decrease. It is in. In particular, the tendency is remarkable in a hybrid vehicle in which EV traveling can be the main traveling mode, such as a plug-in hybrid vehicle (PHV). For this reason, the hybrid vehicle has a technical problem that it becomes difficult to perform the purge process because the period during which the purge process using the negative pressure of the internal combustion engine as described above can be performed decreases. . Further, even in a vehicle having only an internal combustion engine as a drive source, the negative pressure of the internal combustion engine tends to decrease for the purpose of improving fuel consumption. Therefore, the purge process using the negative pressure of the internal combustion engine as described above is performed. It becomes difficult.

  On the other hand, in the apparatus disclosed in Patent Document 1 or 3 described above, by using a vehicle cooler or an air-conditioning air conditioning system, heat exchange is performed between the refrigerant or cold air and the evaporated fuel, thereby evaporating fuel. Since cooling is performed, the evaporated fuel cannot be sufficiently cooled, and it may be difficult to liquefy the evaporated fuel.

  The present invention has been made in view of, for example, the above-described problems. For example, it is an object of the present invention to provide an evaporative fuel processing apparatus that can reliably perform a canister purge process without using the negative pressure of an internal combustion engine. To do.

  In order to solve the above problems, an evaporative fuel processing apparatus of the present invention has an air conditioner system having a refrigerant circulation circuit that circulates refrigerant, a canister that can adsorb evaporative fuel generated in a fuel tank that stores fuel, and the refrigerant circulation circuit. The refrigerant introduced into the canister from the canister and the refrigerant introduced into the canister by the refrigerant introduction means together with the evaporated fuel desorbed from the canister by the introduced refrigerant as the mixture. Refrigerant return means for returning to the circulation circuit, and fuel recirculation means for liquefying the evaporated fuel contained in the mixture returned to the refrigerant circulation circuit by the refrigerant return means and returning it to the fuel tank.

  The evaporative fuel processing apparatus of the present invention includes, for example, a canister mounted on a vehicle and capable of adsorbing evaporative fuel (that is, vapor) generated in, for example, a fuel tank that stores fuel of an internal combustion engine. The fuel tank and the canister are connected via an evaporative fuel passage, and the vapor flows from the fuel tank into the canister and is adsorbed. The air-conditioning system is an air-conditioning system (that is, an air-conditioning system) that air-conditions a vehicle interior of the vehicle on which the evaporative fuel treatment device is mounted. For example, a refrigerant that circulates a refrigerant such as carbon dioxide (CO2) that is a natural refrigerant. It has a circulation circuit. The refrigerant circuit typically includes a compressor (compressor), a condenser (condenser), an expansion valve, and an evaporator (evaporator) connected to each other via a refrigerant passage.

  In particular, the present invention includes a refrigerant introduction unit and a refrigerant return unit. The refrigerant introduction means is configured to be able to introduce the refrigerant from the refrigerant circulation circuit to the canister, and has, for example, a refrigerant introduction passage that communicates the refrigerant passage of the refrigerant circulation circuit with the canister. The refrigerant return means is configured to be able to return the refrigerant introduced into the canister together with the evaporated fuel desorbed from the canister as a mixture to the refrigerant circulation circuit. For example, the refrigerant return means communicates the canister and the refrigerant passage of the refrigerant circulation circuit. And a refrigerant return passage. Therefore, by introducing the refrigerant into the canister by the refrigerant introduction means, the evaporated fuel adsorbed on the canister (more specifically, the adsorbent included in the canister) can be desorbed from the canister. That is, it is possible to perform a purge process in which the evaporated fuel adsorbed on the canister is desorbed (or released) from the canister by the refrigerant introduced from the refrigerant circulation circuit to the canister by the refrigerant introduction means. The mixture containing the evaporated fuel and the refrigerant desorbed from the canister is returned to the refrigerant circulation circuit by the refrigerant return means.

  Further, in the present invention, there is provided fuel recirculation means that liquefies the evaporated fuel contained in the mixture returned to the refrigerant circulation circuit by the refrigerant return means and returns it to the fuel tank. The fuel recirculation means is provided between, for example, an expansion valve and an evaporator in the refrigerant circulation circuit, and a gas-liquid separator that liquefies and separates the evaporated fuel from the mixture, and an evaporated fuel that is liquefied and separated by the gas-liquid separator And a fuel recovery passage for returning the fuel to the fuel tank. Therefore, the evaporated fuel contained in the mixture returned to the refrigerant circulation circuit and desorbed from the canister by the refrigerant can be reliably recovered as a liquid fuel in the fuel tank. Here, according to the present invention, the evaporated fuel is allowed to flow as a mixture together with the refrigerant in the refrigerant circuit of the air conditioner system, and the evaporated fuel contained in the mixture is liquefied by, for example, a gas-liquid separator. The efficiency of liquefying the evaporated fuel can be improved by performing heat exchange between the refrigerant or cold air of the air conditioner system and the evaporated fuel, as compared with the case where the evaporated fuel is cooled and liquefied. In addition, according to the present invention, there is little or no decrease in the cooling capacity of the air conditioning system.

  As described above, according to the present invention, for example, the canister purge process can be reliably performed using the refrigerant of the air conditioner system without using the negative pressure of the internal combustion engine. The evaporated fuel desorbed from the canister can be liquefied and collected in the fuel tank.

  In one aspect of the evaporated fuel processing apparatus of the present invention, the refrigerant circulation circuit includes a compressor, a condenser, an expansion valve, and an evaporator that are connected to each other via a refrigerant passage, and the fuel recirculation means is in the refrigerant circulation circuit. A gas-liquid separator provided between the expansion valve and the evaporator and configured to liquefy and separate the evaporated fuel from the mixture; and a fuel recovery passage for returning the evaporated fuel separated by the gas-liquid separator to the fuel tank; Have

  According to this aspect, in the refrigerant circulation circuit, the vaporized fuel is liquefied from the mixture by the gas-liquid separator and returned to the fuel tank by the fuel recovery passage in a state where the mixture is at a low temperature and low pressure by the expansion valve. Can do.

  In the refrigerant circulation circuit, the compressor, the condenser, the expansion valve, and the evaporator are connected to each other so that the refrigerant circulates through the compressor, the condenser, the expansion valve, and the evaporator in this order. A compressor (ie, a compressor) compresses a refrigerant (eg, carbon dioxide). The refrigerant becomes a high temperature and high pressure state by being compressed by the compressor. The condenser (that is, the condenser) condenses (that is, liquefies) the refrigerant compressed by the compressor. The refrigerant becomes a low temperature and high pressure state by being condensed by the condenser. The expansion valve decompresses the refrigerant condensed by the condenser by throttle expansion. The refrigerant is in a low temperature and low pressure state by being decompressed by the expansion valve. The evaporator (that is, the evaporator) evaporates (in other words, vaporizes) the refrigerant decompressed by the expansion valve. The refrigerant is brought into a high temperature and low pressure state by being evaporated by the evaporator.

  In the aspect in which the refrigerant circulation circuit described above includes a compressor, a condenser, an expansion valve, and an evaporator, the refrigerant introduction means includes a refrigerant passage located downstream of the evaporator and upstream of the compressor in the refrigerant circulation circuit, and You may have the refrigerant | coolant introduction channel | path which connects a canister.

  In this case, the high-temperature and low-pressure refrigerant after passing through the evaporator can be introduced into the canister by the refrigerant introduction means. Therefore, the evaporated fuel adsorbed on the canister can be desorbed from the canister by the refrigerant in a high temperature and low pressure state. That is, the purge process can be performed with a refrigerant in a high temperature and low pressure state. Therefore, it is possible to suppress a decrease in the temperature of the canister due to the introduction of the refrigerant into the canister, and it is possible to suppress the evaporative fuel from becoming difficult to desorb from the canister. Therefore, the evaporated fuel can be efficiently desorbed from the canister. That is, the efficiency of the purge process can be improved.

  In the aspect in which the fuel recirculation means includes the fuel recovery passage, the fuel recirculation means may further include a return opening / closing valve provided in the fuel recovery passage and capable of opening and closing the fuel recovery passage.

  In this case, for example, when the inside of the fuel tank is under a negative pressure, the return on-off valve is opened, so that the evaporated fuel separated by the gas-liquid separator (that is, liquefied evaporated fuel, that is, fuel) Can be effectively returned to the fuel tank.

  In another aspect of the fuel vapor processing apparatus of the present invention, the temperature of the refrigerant introduced into the canister by the refrigerant introduction means and the temperature of the mixture returned to the refrigerant circulation circuit by the refrigerant recirculation means When the temperature difference detecting means for detecting the difference and the temperature difference detected by the temperature difference detecting means are equal to or smaller than a predetermined reference temperature difference, the introduction of the refrigerant from the refrigerant circulation circuit to the canister is stopped. And a refrigerant introduction control means for controlling the refrigerant introduction means.

  According to this aspect, it is possible to avoid wastefully performing the purge process using the refrigerant of the air conditioner system. Here, when there is little or no temperature difference between the temperature of the refrigerant introduced from the refrigerant circulation circuit to the canister and the temperature of the mixture returned from the canister to the refrigerant circulation circuit, the evaporated fuel is adsorbed on the canister. It is not considered.

  The predetermined reference temperature difference is, for example, estimated that there is little or no evaporated fuel adsorbed on the canister, and the temperature of the refrigerant introduced from the refrigerant circuit to the canister and the canister to the refrigerant circuit. What is necessary is just to determine experimentally, empirically, simulation etc. as an upper limit of the temperature difference with the temperature of the returned mixture.

  In the aspect in which the fuel recirculation means has a return opening / closing valve, the refrigerant return means is provided in the refrigerant return passage for communicating the canister and the refrigerant circulation circuit, and in the refrigerant return passage, and opens and closes the refrigerant return passage. A pressure detecting means for detecting a pressure inside at least one of the fuel tank and the canister, and the fuel tank and the canister by introducing the refrigerant into the fuel tank and the canister. After controlling the refrigerant introducing means, the refrigerant on-off valve, and the return on-off valve so that the canister is in a pressurized state, at least the fuel tank and the canister are based on the pressure detected by the pressure detecting means. An abnormality determination unit that determines whether an abnormality has occurred on one side may be further provided.

  In this case, a system including a canister and a fuel tank can be used as an inspection target system, and an inspection for detecting an abnormality such as perforation can be performed using the refrigerant of the air conditioner system.

  In another aspect of the evaporated fuel processing apparatus of the present invention, the apparatus further comprises an air conditioner control means for starting the air conditioner system in accordance with an estimated value of the adsorption amount of the evaporated fuel adsorbed by the canister.

  According to this aspect, the air conditioner control means has an estimated value of the adsorption amount of the evaporated fuel adsorbed on the canister (that is, the adsorption amount of the evaporated fuel estimated to be adsorbed on the canister), for example, a predetermined reference adsorption. When the purge process is required more than the amount and the air conditioner system is not operating, the air conditioner system is activated (in other words, the air conditioner system is forcibly activated). Therefore, when the purge process is necessary, the purge process using the refrigerant of the air conditioner system can be reliably performed.

  The effect | action and other gain of this invention are clarified from the form for implementing invention demonstrated below.

It is a mimetic diagram of a vehicle provided with an evaporation fuel processing device concerning a 1st embodiment. It is a table | surface which shows the opening / closing state of the action valve for every operation state of a vehicle. It is a flowchart for demonstrating stop control of the purge process based on an entrance / exit temperature difference. It is a flowchart which shows the flow of perforation detection in 1st Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
The evaporated fuel processing apparatus according to the first embodiment will be described with reference to FIGS. 1 to 4.

  First, an overall configuration of a vehicle provided with an evaporated fuel processing apparatus according to the present embodiment will be described with reference to FIG.

  FIG. 1 is a schematic view of a vehicle equipped with an evaporated fuel processing apparatus according to this embodiment.

  In FIG. 1, a vehicle 10 equipped with an evaporated fuel processing apparatus according to the present embodiment includes an engine 200, a fuel tank 300, a canister 400, an air conditioner system 500, and an ECU 100.

  The engine 200 is an internal combustion engine that functions as a drive source of the vehicle 10, and is a gasoline engine that uses gasoline as fuel. The engine 200 burns an air-fuel mixture of fuel and intake air (that is, air guided from the outside) inside the cylinder, and converts the internal piston motion generated according to the explosive force into a rotational motion, thereby converting the vehicle 10. Is configured to be drivable. The engine 200 is not limited to a gasoline engine, and may be a diesel engine using light oil as a fuel or a bi-fuel engine that can use a mixed fuel of alcohol and gasoline.

  The engine 200 is provided with an intake passage 210 for guiding intake air from the outside to the inside of the cylinder. An air cleaner 220 is disposed in the intake passage 210 to purify air sucked from the outside. A throttle valve 212 for adjusting the amount of intake air into the cylinder is disposed on the downstream side (cylinder side) of the air cleaner 220 in the intake passage 210. In the engine 200, the intake air sucked from the outside by the intake passage 210 and the fuel injected from the injector 214 which is a fuel injection device are mixed (that is, an air-fuel mixture is formed), and this air-fuel mixture is combusted. .

  The fuel tank 300 is a fuel tank for storing the fuel of the engine 200. The fuel tank 300 is provided with an inlet pipe 310 that is a pipe for supplying fuel into the fuel tank 300. A fuel cap 312 is detachably attached to the oil filler port 311 of the inlet pipe 310. A check valve 313 that prevents the fuel in the fuel tank 300 from flowing back through the inlet pipe 310 and flowing from the fuel tank 300 toward the fuel filler 311 is provided at the end of the inlet pipe 310 opposite to the fuel filler 311. It has been. A vent line 320 is connected in the vicinity of the oil filler port 311 of the inlet pipe 310. The vent line 320 returns the evaporated fuel (that is, vapor) in the fuel tank 300 to the vicinity of the fuel inlet 311 of the inlet pipe 310 at the time of fueling, and reduces the amount of air entering the fuel tank 300 from the fuel inlet 11. Is provided.

  A fuel pump 330 and a remaining amount sensor 340 are disposed in the fuel tank 300. The fuel pump 330 is a pump device configured to suck up fuel stored in the fuel tank 300. A feed pipe 350 reaching the injector 214 of the engine 200 is connected to the fuel pump 330, and fuel sucked up by the fuel pump 330 is supplied to the injector 214 via the feed pipe 350. The remaining amount sensor 340 is a float type liquid level sensor, and is configured to detect the remaining amount of fuel in the fuel tank 300 by quantifying it. The remaining amount sensor 340 is electrically connected to the ECU 100. The remaining amount of fuel detected by the remaining amount sensor 340 is referred to by the ECU 100 at a constant or indefinite period.

  Connected to the upper portion of the fuel tank 300 is an evaporation line 360 that is an evaporative fuel passage that allows communication between a canister 400 (to be described later) and a fuel liquid level upper space in the fuel tank 300. An ORVR valve (Onboard refueling vapor recovery valve) 371 and a COV (Cut Off Valve) 372 are provided at a connection portion between the evaporation line 360 and the fuel tank 300. The ORVR valve 371 is configured to close when the liquid level rises during refueling, and to block communication between the evaporation line 360 and the fuel tank 300. Further, the ORVR valve 371 is configured to block the communication between the evaporation line 360 and the fuel tank 300 even when the vehicle falls or the like, and the fuel in the fuel tank 300 does not leak to the outside via the evaporation line 360. ing. The COV 372 is arranged in parallel with the ORVR valve 371 and is configured to block communication between the evaporation line 360 and the fuel tank 300 when the liquid level rises further than the ORVR valve 371. The COV 372 maintains its open state even after the ORVR valve 371 is closed when the liquid level rises during refueling. However, the COV 372 is closed when the liquid level reaches the COV 372 due to the fluctuation of the liquid level caused by turning of the vehicle. The communication between the evaporation line 360 and the fuel tank 300 is cut off, and the fuel in the fuel tank 300 is not leaked to the outside through the evaporation line 360.

  A pressure sensor 345 is provided on the upper surface of the fuel tank 300. The pressure sensor 345 is a pressure sensor configured to be able to detect the pressure in the fuel tank 300 (that is, the tank internal pressure). The pressure sensor 345 is electrically connected to the ECU 100. The tank internal pressure detected by the pressure sensor 345 is referred to by the ECU 100 at a constant or indefinite period.

  The evaporation line 360 is provided with a block valve 370. The blocking valve 370 is a valve device configured to be able to open and block the evaporation line 360 by an opening / closing operation. When the blocking valve 370 is in the closed state, the evaporation line 360 is blocked and the communication between the fuel tank 300 and the canister 400 is blocked. The blocking valve 370 is connected to the ECU 100, and its opening / closing operation is controlled by the ECU 100. A refrigerant introduction passage 610 is connected to the canister 400 side of the blocking valve 370 in the evaporation line 360. The refrigerant introduction passage 610 is a tubular member for introducing the refrigerant from the air conditioner system 500 described later to the canister 400. The configuration of the refrigerant introduction passage 610 will be described later.

  The canister 400 is an adsorption device provided with an adsorbent 410 such as activated carbon capable of adsorbing and holding the evaporated fuel (that is, vapor) generated in the fuel tank 300 therein. The canister 400 is connected to three types of pipes, the above-described evaporation line 360, the atmosphere communication pipe 420, and the refrigerant return passage 620.

  The atmosphere communication pipe 420 is a tubular member that communicates with a space outside the vehicle (in other words, the atmosphere) of the vehicle 10, and is connected to the canister 400. The atmosphere communication pipe 420 is provided with an atmosphere valve 421 capable of opening and closing the atmosphere communication pipe 420 by an opening / closing operation. When the atmospheric valve 421 is open, the atmosphere communicates with the canister 400 via the atmospheric communication pipe 420, and when the atmospheric valve 421 is closed, the atmosphere communicates with the canister 400. Communication through the tube 420 is blocked. The atmospheric valve 421 is connected to the ECU 100, and its opening / closing operation is controlled by the ECU 100.

  The refrigerant return passage 620 is a vaporized fuel (that is, vapor) that has been introduced from the air conditioner system 500 into the canister 400 via the refrigerant introduction passage 610 described above and desorbed from the adsorbent 410 of the canister 400 by the introduced refrigerant. ) And a tubular member for returning to the air conditioner system 500 as a mixture. The configuration of the refrigerant return passage 620 will be described later.

  The canister 400 is provided with a pressure sensor 430. The pressure sensor 430 is a pressure sensor configured to be able to detect the pressure in the canister 400. The pressure sensor 430 is electrically connected to the ECU 100. The pressure detected by the pressure sensor 430 is referred to by the ECU 100 at a constant or indefinite period.

  The air-conditioning system 500 is an air-conditioning system that air-conditions the vehicle interior of the vehicle 10, and includes a refrigerant circulation circuit 500a that circulates a refrigerant such as carbon dioxide (CO2) that is a natural refrigerant. The refrigerant circulation circuit 500a includes a compressor 510, a condenser 520, an expansion valve 530, and an evaporator 540 that are connected to each other via a refrigerant passage 590. The compressor 510, the condenser 520, the expansion valve 530, and the evaporator 540 are arranged so that the refrigerant circulates through the compressor 510, the condenser 520, the expansion valve 530, and the evaporator 540 in this order (that is, the refrigerant is the compressor 510, the condenser 520, and the expansion valve 530). , Evaporator 540, compressor 510, condenser 520,... In this order) are connected to each other. In FIG. 1, arrows R1, R2, R3, and R4 indicate the direction in which the refrigerant flows in the refrigerant circuit 500a.

  The compressor 510 is a compressor that compresses a refrigerant, for example, CO2. The refrigerant becomes a high temperature and high pressure state by being compressed by the compressor 510.

  The condenser 520 is a condenser that condenses (that is, liquefies) the refrigerant compressed by the compressor 510. The refrigerant becomes a low temperature and high pressure state by being condensed by the condenser 520.

  The expansion valve 530 is an expansion valve (expansion valve) that decompresses the refrigerant condensed by the condenser 520 by throttle expansion. The refrigerant is reduced in temperature and pressure by being decompressed by the expansion valve 530.

  The evaporator 540 is an evaporator that evaporates (in other words, vaporizes) the refrigerant decompressed by the expansion valve 530. The refrigerant becomes a high temperature and low pressure state by being evaporated by the evaporator 540. The refrigerant brought into a high temperature and low temperature state by the evaporator 540 is guided to the compressor 510 by the refrigerant passage 590 and is compressed again by the compressor 510.

  The ECU 100 is an electronic control unit that includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and is configured to be able to control the entire operation of the vehicle 10. The ECU 100 is configured to be able to control purge processing and perforation detection described later.

  In FIG. 1, the vehicle 10 further includes a refrigerant introduction passage 610, a three-way valve 611, a refrigerant return passage 620, a refrigerant on-off valve 621, a gas-liquid separator 630, a fuel recovery passage 640, and a return on-off valve 641.

  As described above, the refrigerant introduction passage 610 is a tubular member for introducing the refrigerant from the air conditioner system 500 to the canister 400. One end of the refrigerant introduction passage 610 is connected to the refrigerant passage 590 and the three-way valve 611 between the evaporator 540 and the compressor 510 in the refrigerant circulation circuit 500a of the air conditioner system 500 (that is, downstream of the evaporator 540 and upstream of the compressor 510). Connected through. The other end of the refrigerant introduction passage 610 is connected to the canister 400 side with respect to the closing valve 370 in the evaporation line 360 and communicates with the canister 400.

  The three-way valve 611 is provided in the refrigerant passage 590 between the evaporator 540 and the compressor 510 in the refrigerant circulation circuit 500a (that is, downstream of the evaporator 540 and upstream of the compressor 510), and the three-way valve 611 and the evaporator 540 are provided. The three-way valve configured to be able to selectively communicate the refrigerant passage 590 (590a) between the refrigerant passage 590 and the refrigerant introduction passage 610 with the refrigerant passage 590 (590b) between the three-way valve 611 and the condenser 510. It is. In other words, the three-way valve 611 is configured such that the direction in which the refrigerant that has passed through the evaporator 540 flows is a direction toward the compressor 510 (hereinafter referred to as “air conditioner side direction”) and a direction toward the canister 400 (hereinafter referred to as “canister side direction”). The three-way valve is configured so as to be switchable between. The three-way valve 611 is connected to the ECU 100 and its operation is controlled by the ECU 100.

  As described above, the refrigerant return passage 620 includes the refrigerant introduced into the canister 400 from the air conditioner system 500 through the refrigerant introduction passage 610 together with the vapor desorbed from the adsorbent 410 of the canister 400 by the introduced refrigerant. It is a tubular member for returning to the air conditioner system 500 as a mixture. One end of the refrigerant return passage 620 communicates with the canister 400. The other end of the refrigerant return passage 620 communicates with the refrigerant passage 590 (590b) on the compressor 510 side from the three-way valve 611 in the refrigerant circulation circuit 500a of the air conditioner system 500.

  The refrigerant open / close valve 621 is a valve device that is provided in the refrigerant return passage 620 and configured to be able to open and close the refrigerant return passage 620 by an opening / closing operation. When the refrigerant on-off valve 621 is in the open state, the canister 400 and the refrigerant passage 590b communicate with each other via the refrigerant return passage 620, and when the refrigerant on-off valve 621 is in the closed state, the canister 400 and the refrigerant Communication with the passage 590b via the refrigerant return passage 620 is blocked. The refrigerant open / close valve 621 is connected to the ECU 100, and the opening / closing operation thereof is controlled by the ECU 100.

  The gas-liquid separator 630 is provided between the expansion valve 530 and the evaporator 540 in the refrigerant circulation circuit 500a, and is configured to be able to liquefy and separate the vapor from the mixture including the refrigerant and the vapor. It is. In other words, the gas-liquid separator 630 separates the mixture after passing through the expansion valve 530 into refrigerant and fuel (that is, liquefied paper), causes the refrigerant to flow into the evaporator 540 side, and recovers the fuel. This is a gas-liquid separator configured to be able to flow into the passage 640.

  The fuel recovery passage 640 is a tubular member for returning the vapor (that is, fuel) liquefied and separated by the gas-liquid separator 630 to the fuel tank 300. One end of the fuel recovery passage 640 is connected to the gas-liquid separator 630. The other end of the fuel recovery passage 640 is connected to the fuel tank 300 side with respect to the sealing valve 370 in the evaporation line 360 and communicates with the fuel tank 300.

  The return opening / closing valve 641 is a valve device that is provided in the fuel recovery passage 640 and configured to be able to open and close the fuel recovery passage 640 by an opening / closing operation. When the return on-off valve 641 is open, the gas-liquid separator 630 and the fuel tank 300 communicate with each other via the fuel recovery passage 640, and when the return on-off valve 641 is in the closed state, Communication between the liquid separator 630 and the fuel tank 300 through the fuel recovery passage 640 is blocked. The return opening / closing valve 641 is connected to the ECU 100, and its opening / closing operation is controlled by the ECU 100.

  Next, the operation of the fuel vapor processing apparatus according to this embodiment will be described with reference to FIGS. 2 to 4 in addition to FIG.

  First, canister purge processing by the evaporative fuel processing apparatus according to the present embodiment will be described with reference to FIGS. 1 to 3.

  FIG. 2 shows the opening / closing of the blocking valve 370, the atmospheric valve 421, the refrigerant opening / closing valve 621, the three-way valve 611, and the return opening / closing valve 641 (hereinafter collectively referred to as “operating valve” as appropriate) for each operation state of the vehicle 10. It is a table | surface which shows a state.

  In the table shown in FIG. 2, column C1 is described later as one of OBD (On-Board Diagnostics) when the vehicle 10 is in a running state and the air conditioner system 500 is in operation (that is, in an ON state). The open / closed state of each actuating valve when the perforated detection is performed is shown. Column C2 shows the open / closed state of each operating valve when the vehicle 10 is in a traveling state, the air conditioner system 500 is operating, and the perforation detection is not executed. Column C3 shows the open / close state of each operation valve when the vehicle 10 is in a traveling state and the air conditioner system 500 is not operating (ie, in an OFF state). Column C4 shows the open / close state of each operating valve when the vehicle 10 is being refueled. Column C5 shows the open / close state of each operating valve when the vehicle 10 is parked.

  In FIG. 2, when the vehicle 10 is parked as shown in the column C5, the block valve 370 is closed, and the communication between the fuel tank 300 and the canister 400 is blocked. Thereby, the vapor generated in the fuel tank 300 while the vehicle 10 is parked can be enclosed in the fuel tank 300. Thus, the canister 400 can be prevented from adsorbing vapor. When the vehicle 10 is parked, the atmospheric valve 421 and the refrigerant on / off valve 621 are closed, and the three-way valve 611 is set to “air conditioner side” (that is, the refrigerant that has passed through the evaporator 540). The return on-off valve 640 is basically closed when the flow direction is the air conditioner side direction), and is opened when the tank internal pressure is negative.

  On the other hand, as shown in row C4, when the vehicle 10 is being refueled, the blocking valve 370 is opened to reduce the release of vapor to the atmosphere, and the fuel tank 300 and the canister 400 are in communication with each other. To do. Accordingly, the vapor generated in the fuel tank 300 is guided to the canister 400 by the evaporation line 360 and is adsorbed by the adsorbent 410 of the canister 400. When the vehicle 10 is parked, the atmospheric valve 421 is opened, the refrigerant on / off valve 621 is closed, the three-way valve 611 is “air conditioner side”, and the return on / off valve 640 is The valve is closed.

  Here, since the adsorption capacity of the adsorbent 410 of the canister 400 to adsorb vapor is limited, the vapor adsorbed by the adsorbent 410 during refueling of the vehicle 10 is desorbed from the adsorbent 410 as described above. It is necessary to carry out a purge process for discharging.

  Particularly in the present embodiment, as described above, the vehicle 10 includes the refrigerant introduction passage 610, the three-way valve 611, the refrigerant return passage 620, the refrigerant on-off valve 621, the gas-liquid separator 630, the fuel recovery passage 640, and the return on-off valve 641. Thus, the purge process can be reliably performed using the refrigerant of the air conditioner system 500.

  In the present embodiment, the purge process is performed when the vehicle 10 is in a traveling state, the air conditioner system 500 is in operation, and no perforation detection described later is performed. When the purge process is performed (that is, when the vehicle 10 is in a traveling state, the air conditioner system 500 is operating, and no perforation detection is performed), as shown in the column C2 of FIG. The blocking valve 370 is closed, the atmospheric valve 421 is closed, the refrigerant opening / closing valve 621 is opened, and the three-way valve 611 is “canister side” (that is, the refrigerant that has passed through the evaporator 540). The return on / off valve 641 is basically in a closed state and is opened when the tank internal pressure is negative.

  In FIG. 1 and FIG. 2, when each operating valve is in the open / close state for purge processing (that is, the open / close state shown in column C2 in FIG. 2), first, the refrigerant after passing through the evaporator 540 is The canister 400 is introduced by the three-way valve 611 and the refrigerant introduction passage 610. Therefore, the vapor adsorbed on the adsorbent 410 of the canister 400 can be desorbed from the adsorbent 410 by the refrigerant introduced into the canister 400 from the refrigerant circulation circuit 500a (that is, the canister 400 is purged). it can). Next, the mixture of the refrigerant introduced into the canister 400 and the vapor desorbed from the adsorbent 410 by the refrigerant is returned to the refrigerant passage 590b of the refrigerant circulation circuit 500a by the refrigerant return passage 620. Next, the mixture returned to the refrigerant circulation circuit 500a sequentially passes through the compressor 510, the condenser 520, and the expansion valve 530, and then is separated into refrigerant and fuel by the gas-liquid separator 630. The refrigerant separated by the gas / liquid separator 630 flows into the evaporator 540, and the fuel separated by the gas / liquid separator 630 flows into the fuel recovery passage 640. The fuel that has flowed into the fuel recovery passage 640 is temporarily retained in the fuel recovery passage 640 by a return on-off valve 641 that is basically closed, and the return on-off valve 641 opens when the tank internal pressure is negative. The fuel tank 300 is returned to the state.

  Thus, according to the present embodiment, the purge process can be performed using the refrigerant of the air conditioner system 500. Therefore, for example, since the engine 200 is stopped for a long period or a large number of times or because the negative pressure of the engine 200 is low, it is difficult to perform the canister 400 purge process using the negative pressure of the engine 200. Even in this case, the canister 400 can be reliably purged. Furthermore, there is no need to perform fuel correction (for example, correction of the injection amount of fuel injected from the injector 214) associated with the purge process, which is necessary when performing the purge process using the negative pressure of the engine 200. The air-fuel ratio controllability of the engine 200 can be improved. In addition, the vapor desorbed from the canister 400 by the refrigerant contained in the mixture returned to the refrigerant circulation circuit 500a can be reliably recovered in the fuel tank 300 as a liquid fuel.

  In FIG. 1, in the present embodiment, in particular, the refrigerant introduction passage 610 is configured to communicate the refrigerant passage 590 located downstream of the evaporator 540 and upstream of the compressor 510 with the canister 400 in the refrigerant circulation circuit 500a. Has been. Therefore, the high-temperature and low-pressure refrigerant after passing through the evaporator 540 can be introduced into the canister 400 through the refrigerant introduction passage 610. Accordingly, the vapor adsorbed on the canister 400 can be desorbed from the canister 400 by the refrigerant in a high temperature and low pressure state. That is, the purge process can be performed with a refrigerant in a high temperature and low pressure state. Thereby, it is possible to suppress a decrease in the temperature of the canister 400 due to the introduction of the refrigerant into the canister 400, and it is possible to suppress the vapor from becoming difficult to desorb from the canister 400. Therefore, the vapor can be efficiently detached from the canister 400. That is, the efficiency of the purge process can be improved.

  Further, particularly in the present embodiment, the return on / off valve 641 is provided in the fuel recovery passage 640 as described above, and the return on / off valve 641 is opened so that the valve is opened when the tank internal pressure is negative. Controlled by. Therefore, the vapor (ie, fuel) liquefied by the gas-liquid separator 630 can be effectively returned to the fuel tank 300 via the fuel recovery passage 640 and the return opening / closing valve 641.

  In addition, particularly in the present embodiment, the ECU 100 has an estimated value of the amount of adsorption of the vapor adsorbed on the canister 400 (that is, the amount of adsorption of the vapor estimated to be adsorbed on the adsorbent 410 of the canister 400). If the purge amount is greater than the predetermined reference adsorption amount and the air conditioner system 500 is not operating, the air conditioner system 500 is activated (in other words, the air conditioner system 500 is forcibly operated). To be configured). Therefore, when the purge process is necessary, the purge process using the refrigerant of the air conditioner system 500 as described above can be reliably performed. As an aspect for obtaining an estimated value of the adsorption amount adsorbed on the canister 400 (in other words, an estimation aspect for estimating the adsorption amount adsorbed on the canister 400), various known aspects can be adopted. For example, the ECU 100 may obtain an estimated value of the adsorption amount based on the tank internal pressure, the temperature of the fuel in the fuel tank 300, and the valve opening period of the block valve 370, or directly detect the vapor adsorption amount in the canister 400 A detection unit configured to be able to be provided may be provided in the canister 400, and the detection result may be referred to by the ECU 100 as an estimated value of the adsorption amount.

  In FIG. 2, as shown in column C3, when the vehicle 10 is running and the air conditioner system 500 is stopped, the blocking valve 370, the atmospheric valve 421, and the refrigerant on-off valve 621 are closed. The three-way valve 611 is set to “air conditioner side”, the return on-off valve 640 is basically closed, and is opened when the tank internal pressure is negative.

  In FIG. 1, in particular, in the present embodiment, the canister 400 has a refrigerant circulation circuit connected to the temperature of the refrigerant introduced to the canister 400 through the refrigerant introduction passage 610 (hereinafter referred to as “inlet temperature” as appropriate) and the refrigerant return passage 620. A temperature sensor 650 capable of detecting the temperature of the mixture returned to 500a (hereinafter appropriately referred to as “outlet temperature”) is provided. Furthermore, when the temperature difference between the temperature of the refrigerant introduced into the canister 400 and the temperature of the mixture returned to the refrigerant circulation circuit 500a, detected by the temperature sensor 650, is equal to or less than a predetermined reference temperature difference. Then, the three-way valve 611 is controlled so that the introduction of the refrigerant from the refrigerant circulation circuit 500a to the canister 400 is stopped (that is, the three-way valve 611 is set to the “air conditioner side”). That is, the ECU 100 performs stop control of the purge process based on the temperature difference between the inlet temperature and the outlet temperature. Therefore, it is possible to avoid performing the purge process using the refrigerant of the air conditioner system 500 wastefully. Here, when there is little or no temperature difference between the inlet temperature and the outlet temperature, it is considered that no vapor is adsorbed on the canister 400. Hereinafter, the temperature difference between the inlet temperature and the outlet temperature will be appropriately referred to as “entrance / exit temperature difference”. The temperature sensor 650, together with the ECU 100, constitutes an example of “temperature difference detection means” according to the present invention.

  The purge control stop control based on such an inlet / outlet temperature difference will be described with reference to FIG.

  FIG. 3 is a flowchart for explaining the purge control stop control based on the inlet / outlet temperature difference.

  In FIG. 3, first, the ECU 100 determines whether or not there is a request for purge processing (step S110). That is, the ECU 100 determines whether or not the above-described purge process of the canister 400 is being performed.

  When it is determined that there is no request for purge processing (that is, when it is determined that purge processing is not being performed) (step S110: No), for example, whether there is a request for purge processing again after a predetermined time. Is determined by the ECU 100 (step S110).

  On the other hand, when it is determined that there is a request for the purge process (that is, when it is determined that the purge process is being performed) (step S110: Yes), the above-described inlet / outlet temperature difference is measured (step S120). ). That is, the temperature difference between the inlet temperature (ie, the temperature of the refrigerant introduced into the canister 400 by the refrigerant introduction passage 610) and the outlet temperature (ie, the temperature of the mixture returned to the refrigerant circulation circuit 500a by the refrigerant return passage 620). A certain entrance / exit temperature difference is detected by the temperature sensor 650, and the detected entrance / exit temperature difference is referred to by the ECU 100.

  Next, it is determined by the ECU 100 whether or not there is an entrance / exit temperature difference (step S130). That is, the ECU 100 determines whether the entrance / exit temperature difference detected by the temperature sensor 650 is greater than a predetermined reference temperature. Specifically, when the entrance / exit temperature difference detected by temperature sensor 650 is larger than a predetermined reference temperature difference, ECU 100 determines that “there is an entrance / exit temperature difference”, and the entrance / exit temperature detected by temperature sensor 650. When the difference is equal to or less than the predetermined reference temperature difference, the ECU 100 determines that “there is no temperature difference between the entrance and the exit”.

  If it is determined that there is an inlet / outlet temperature difference (step S130: Yes), the purge process is continued (step S140). That is, when there is an inlet / outlet temperature difference, the ECU 100 controls each operating valve so that the purge process is executed (that is, maintains each operating valve in the open / closed state shown in the column C2 in FIG. 2). ).

  When it is determined that there is no difference between the entrance and exit temperature (step S130: No), the purge process is stopped (step S150). That is, when there is no inlet / outlet temperature difference, the ECU 100 controls each operation valve so that the purge process is stopped (for example, the three-way valve 611 is switched from the “canister side” to the “air conditioner side”).

  Thus, since ECU 100 performs purge control stop control based on the inlet / outlet temperature difference, it is possible to avoid performing the purge process using the refrigerant of the air conditioner system 500 in vain.

  Next, hole detection in the present embodiment will be described with reference to FIG. 4 in addition to FIGS.

  The “perforated detection” in the present embodiment is an inspection for determining whether there is an abnormality such as a hole in the inspection target system using the system including the canister 400 and the fuel tank 300 as the inspection target system. This is an inspection for detecting the occurrence of a leak in the inspection target system (that is, an inspection for determining whether or not a hole for generating a leak is formed in the inspection target system).

  Particularly in the present embodiment, the ECU 100 controls each work valve such that the refrigerant of the air conditioner system 500 is introduced into the fuel tank 300 and the canister 400 so that the fuel tank 300 and the canister 400 are in a pressurized state. Based on the pressure detected by the pressure sensor 430, it is possible to determine whether or not an abnormality has occurred in the inspection target system. Therefore, it is possible to perform a perforated inspection using the refrigerant of the air conditioner system 500 using the system including the canister 400 and the fuel tank 300 as the inspection target system.

  FIG. 4 is a flowchart showing a flow of hole detection in the present embodiment.

  In FIG. 4, first, the ECU 100 determines whether or not there is a request for perforation detection (step S210). That is, ECU 100 determines whether or not a predetermined execution condition for performing perforation detection is satisfied.

  If it is determined that there is no perforation detection request (step S210: No), for example, the ECU 100 determines again whether there is a perforation detection request after a predetermined time (step S210).

  On the other hand, if it is determined that there is a request for perforation detection (step S210: Yes), first, the atmosphere valve 421, the refrigerant on-off valve 621, and the return on-off valve 641 are each closed by the ECU 100 (step S210). S220).

  Next, the ECU 100 opens the blocking valve 370 and sets the three-way valve 611 to “canister side” (step S230). Accordingly, the refrigerant passage 590 (590b), the canister 400, and the fuel tank 300 in the refrigerant circulation circuit 500a communicate with each other, and the refrigerant in the refrigerant circulation circuit 500a is introduced into the canister 400 and the fuel tank 300. Here, since the atmospheric valve 421, the refrigerant on-off valve 621, and the return on-off valve 641 are closed, the refrigerant in the refrigerant circulation circuit 500a is introduced into the canister 400 and the fuel tank 300, whereby the canister 400 and The fuel tank 300 is in a pressurized state. Note that column C1 in FIG. 2 shows the open / close state of each operation valve when the refrigerant in the refrigerant circulation circuit 500a is introduced into the canister 400 and the fuel tank 300 in this way during execution of the perforation inspection.

  Next, the three-way valve 611 is set to the “air conditioner side”, and the ECU 100 starts measuring the change in pressure of the inspection target system (step S240). That is, the ECU 100 measures a change in pressure in the inspection target system including the canister 400 and the fuel tank 300 by referring to the pressure detected by the pressure sensor 430 provided in the canister 400 a plurality of times during a predetermined period. .

  Next, the ECU 100 determines whether or not there is a pressure change in the inspection target system (step S250). That is, the ECU 100 determines whether or not the pressure detected by the pressure sensor 430 during the predetermined period has changed more than a predetermined reference change amount. Note that the predetermined reference change amount is experimental as an upper limit value of the pressure change amount in the inspection target system that may occur when the inspection target system is estimated to have little or no abnormality such as perforation. It may be determined by empirical or simulation.

  When it is determined that there is no pressure change in the inspection target system (step S250: No), the ECU 100 determines that the inspection target system is normal (step S300).

  When it is determined that there is a pressure change in the inspection target system (step S250: Yes), the closing valve 370 is closed by the ECU 100 (step S260).

  Next, ECU 100 determines whether or not there is a pressure change in canister 400 (step S270). That is, the ECU 100 determines whether or not the pressure detected by the pressure sensor 430 changes during a predetermined period after the closing valve 370 is closed.

  If there is a pressure change in the canister 400 (step S270: Yes), the ECU 100 determines that an abnormality such as perforation has occurred in the canister 400 (step 280).

  On the other hand, when there is no pressure change in the canister 400 (step S270: No), the ECU 100 determines that an abnormality such as perforation has occurred in the fuel tank 300 (step S290). That is, when there is a pressure change in the inspection target system including the canister 400 and the fuel tank 300 (step S250), the canister 400 side and the fuel tank 300 side from the closing valve 370 of the inspection target system by closing the closing valve 370. If the pressure on the canister 400 side does not change after the communication with the engine is interrupted (step S260) (step S270: No), the ECU 100 changes the pressure on the fuel tank 300 side relative to the block valve 370 in the system to be inspected. Yes, it is determined that an abnormality such as a hole has occurred on the fuel tank 300 side.

  As described above, according to the present embodiment, it is possible to perform the perforated inspection using the refrigerant of the air conditioner system 500 using the system including the canister 400 and the fuel tank 300 as the inspection target system.

  In this embodiment, the measurement of the pressure change of the inspection target system by the ECU 100 has been described based on an example in which the pressure change detected by the pressure sensor 430 provided in the canister 400 is described. The measurement of the pressure change of the system may be performed based on the pressure detected by the pressure sensor 345 provided in the fuel tank 300. In this case, when the ECU 100 determines that there is a pressure change in the system to be inspected, the ECU 100 determines whether there is a pressure change in the fuel tank 300 after the closing valve 370 is closed, and the pressure change is detected. When there is an abnormality such as a hole in the fuel tank 300, it is determined that there is an abnormality such as a hole in the canister 400.

  As described above, according to this embodiment, the canister 400 can be reliably purged using the refrigerant of the air conditioner system 500 without using the negative pressure of the engine 200, for example. The vapor desorbed from the canister 400 by this purge process can be liquefied and collected in the fuel tank 300. In addition, the system including the canister 400 and the fuel tank 300 can be used as an inspection target system, and it is possible to detect a hole using the refrigerant of the air conditioner system 500.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. Is also included in the technical scope of the present invention.

  DESCRIPTION OF SYMBOLS 100 ... ECU, 200 ... Engine, 300 ... Fuel tank, 360 ... Evaporation line, 370 ... Sealing valve, 400 ... Canister, 421 ... Air valve, 500 ... Air conditioner system, 500a ... Refrigerant circulation circuit, 510 ... Compressor, 520 ... Condenser, 530 ... Expansion valve, 540 ... Evaporator, 610 ... Refrigerant introduction passage, 611 ... Three-way valve, 620 ... Refrigerant return passage, 621 ... Refrigerant on / off valve, 630 ... Gas-liquid separator, 640 ... Fuel recovery passage, 641 ... Return on / off valve

Claims (7)

An air conditioner system having a refrigerant circulation circuit for circulating the refrigerant;
A canister capable of adsorbing evaporated fuel generated in a fuel tank for storing fuel;
Refrigerant introduction means capable of introducing the refrigerant from the refrigerant circulation circuit to the canister;
Refrigerant return means for returning the refrigerant introduced into the canister by the refrigerant introduction means together with the evaporated fuel desorbed from the canister by the introduced refrigerant to the refrigerant circulation circuit as a mixture;
An evaporative fuel processing apparatus comprising: fuel recirculation means for liquefying evaporative fuel contained in the mixture returned to the refrigerant circulation circuit by the refrigerant return means and recirculating it to the fuel tank. The refrigerant circuit has a compressor, a condenser, an expansion valve and an evaporator connected to each other via a refrigerant passage,
The fuel recirculation means includes
A gas-liquid separator that is provided between the expansion valve and the evaporator in the refrigerant circulation circuit and liquefies and separates the evaporated fuel from the mixture;
The evaporated fuel processing apparatus according to claim 1, further comprising: a fuel recovery passage that returns the evaporated fuel separated by the gas-liquid separator to the fuel tank.   The evaporated fuel processing according to claim 2, wherein the refrigerant introduction means includes a refrigerant introduction passage that connects the canister with a refrigerant passage that is located downstream of the evaporator and upstream of the compressor in the refrigerant circulation circuit. apparatus.   The evaporative fuel processing device according to claim 2, wherein the fuel return means further includes a return on-off valve provided in the fuel recovery passage and capable of opening and closing the fuel recovery passage. A temperature difference detection means for detecting a temperature difference between the temperature of the refrigerant introduced into the canister by the refrigerant introduction means and the temperature of the mixture returned to the refrigerant circulation circuit by the refrigerant reflux means;
When the temperature difference detected by the temperature difference detection means is equal to or less than a predetermined reference temperature difference, the refrigerant introduction means is controlled so that introduction of the refrigerant from the refrigerant circulation circuit to the canister is stopped. The evaporative fuel processing apparatus according to any one of claims 1 to 4, further comprising: a refrigerant introduction control unit that performs the following. The refrigerant return means includes a refrigerant return passage for communicating the canister and the refrigerant circulation circuit, and a refrigerant opening / closing valve provided in the refrigerant return passage and capable of opening and closing the refrigerant return passage,
Pressure detecting means for detecting a pressure inside at least one of the fuel tank and the canister;
After controlling the refrigerant introduction means, the refrigerant on-off valve, and the return on-off valve so that the fuel tank and the canister are in a pressurized state by introducing the refrigerant into the fuel tank and the canister, The evaporated fuel processing apparatus according to claim 4, further comprising: an abnormality determination unit that determines whether or not an abnormality has occurred in at least one of the fuel tank and the canister based on a pressure detected by a pressure detection unit.   The evaporative fuel processing apparatus according to any one of claims 1 to 6, further comprising an air conditioner control unit that activates the air conditioner system in accordance with an estimated value of an adsorption amount of the evaporative fuel adsorbed to the canister.

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