JP2012184755A - Fuel vapor treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel vapor treatment device which is small in size and can effectively send out fuel vapor to an intake passage of an internal combustion engine.SOLUTION: An exhaust gas recirculation pipe 51 is connected to an exhaust pipe 41 of an engine 2 at its one end and connected to an intake pipe 31 at the other end, and makes the exhaust gas of the exhaust passage 42 flow back to the intake passage 34. A fuel vapor pipe 54 is connected to a fuel tank 21 at its one end and connected to the exhaust gas recirculation pipe 51 at the other end, and introduces fuel vapor to an exhaust gas recirculation passage 511 through a fuel vapor passage 541 which is formed inside the fuel vapor pipe. Then, when an EGR valve 521 and a purge valve 551 are valve-opened, the fuel vapor of the fuel vapor passage 541 is sucked to the exhaust gas recirculation passage 511 by negative pressure which is generated by the circulation of the exhaust gas in the exhaust gas recirculation passage 511, and the fuel vapor is introduced to the intake passage 34 by a flow of the exhaust gas of the exhaust gas recirculation passage 511 and sent to the engine 2.

Description

  The present invention relates to a fuel vapor processing apparatus that processes fuel vapor generated in a fuel tank.

  Conventionally, in a fuel vapor processing apparatus, fuel vapor is guided to an intake passage by using a negative pressure generated in the intake passage during operation of the internal combustion engine. However, in recent years, there has been a tendency for the negative pressure generated in the intake passage to be reduced due to an increase in fuel efficiency demands on the internal combustion engine, etc., so that the fuel vapor can be guided to the intake passage using the negative pressure. It has become difficult. Therefore, Patent Document 1 proposes that a part of the intake air compressed by the supercharger is accumulated in an accumulator tank, and fuel vapor is sent to the intake passage using the compressed air in the accumulator tank. .

JP 2008-267186 A

  However, the fuel vapor processing apparatus of Patent Document 1 requires a pressure accumulating tank as a constituent element, which causes a problem that the fuel vapor processing apparatus is increased in size. Further, only compressed air corresponding to the volume of the pressure accumulating tank can be used for delivery of fuel vapor, and there is a problem that usage conditions are limited. Further, the fuel vapor processing apparatus of Patent Document 1 has a problem that it can be applied only to an engine system including a supercharger.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a fuel vapor processing apparatus that is small in size and can effectively send fuel vapor to an intake passage of an internal combustion engine. is there.

  The invention according to claim 1 is a fuel vapor processing apparatus that sends and processes fuel vapor generated in a fuel tank to an internal combustion engine, and includes an exhaust gas recirculation pipe, a fuel vapor pipe, an EGR valve, and a purge valve. Prepare. The exhaust gas recirculation pipe has one end connected to the exhaust pipe of the internal combustion engine and the other end connected to the intake pipe of the internal combustion engine. Then, the exhaust gas recirculation pipe recirculates the exhaust gas in the exhaust pipe of the exhaust pipe to the intake gas passage of the intake pipe via the exhaust gas recirculation path formed inside. The fuel vapor pipe has one end connected to the fuel tank and the other end connected to the exhaust gas recirculation pipe. The fuel vapor pipe guides the fuel vapor to the exhaust gas recirculation passage via the fuel vapor passage formed inside. The EGR valve is provided so that the exhaust gas recirculation passage can be opened and closed. The purge valve is provided so that the fuel vapor passage can be opened and closed. When the EGR valve and the purge valve are open, the fuel vapor processing device sucks the fuel vapor in the fuel vapor passage into the exhaust gas recirculation passage by the negative pressure generated by the exhaust gas flowing through the exhaust gas recirculation passage. The fuel vapor is guided to the intake passage by the flow of exhaust gas in the recirculation passage and is sent to the internal combustion engine.

  Thus, in the present invention, the fuel vapor is sent to the intake passage using the exhaust gas recirculated from the exhaust passage of the internal combustion engine to the intake passage. Moreover, in this invention, the pressure accumulation tank which was essential in the invention of the said patent document 1 becomes unnecessary. Therefore, the enlargement of the fuel vapor processing apparatus can be suppressed. Further, in the present invention, when the internal combustion engine is in operation, the fuel vapor delivery action using the exhaust gas can be obtained. Therefore, as in the invention of Patent Document 1, it is possible to avoid a situation in which the fuel vapor delivery action can be obtained only while compressed air is present in the pressure accumulation tank. Therefore, it is possible to obtain a fuel vapor processing apparatus that is small in size and capable of effectively delivering fuel vapor to the intake passage of the internal combustion engine.

  The invention described in claim 2 further includes an EGR valve actuator, a purge valve actuator, and a control unit. The EGR valve actuator drives the EGR valve to open and close. The purge valve actuator opens and closes the purge valve. The controller adjusts the opening degrees of the EGR valve and the purge valve by controlling the operations of the EGR valve actuator and the purge valve actuator. Further, the control unit adjusts the opening degree of the EGR valve based on the load state of the internal combustion engine. Specifically, when the internal combustion engine is at a low load or a medium load, the EGR valve is opened and the purge valve is opened, whereby the fuel vapor is guided to the intake passage by the exhaust flow in the exhaust recirculation passage and is sent to the internal combustion engine. . Further, when the internal combustion engine is at a high load, the EGR valve is closed and the purge valve is opened, so that the fuel vapor is sucked into the intake passage due to the negative pressure generated by the intake air flowing through the intake passage, and is supplied to the internal combustion engine. Send it out.

  Thus, in the present invention, the operation of the EGR valve actuator and the purge valve actuator is controlled by the control unit based on the load state of the internal combustion engine, so that the fuel vapor can be generated by the exhaust flow in the exhaust recirculation passage or the negative pressure in the intake passage. Is guided to the intake passage and sent to the internal combustion engine. Therefore, fuel vapor can be effectively delivered to the intake passage of the internal combustion engine.

  In the invention according to claim 3, the other end of the fuel vapor pipe is connected to the intake pipe side with respect to the EGR valve in the exhaust gas recirculation pipe. Therefore, in the present invention, even when the EGR valve is closed when the internal combustion engine is at a high load, the fuel vapor in the fuel vapor pipe can be sent to the intake passage via the exhaust gas recirculation pipe.

  The inventions according to claims 4, 5 and 6 specifically show the structure of the connecting portion between the fuel vapor pipe and the exhaust gas recirculation pipe. In the invention described in claim 4, the fuel vapor pipe is provided so that the other end protrudes into the exhaust gas recirculation passage.

  In the invention according to claim 5, the exhaust gas recirculation passage is formed so that the connection area between the fuel vapor pipe and the exhaust gas recirculation pipe has a smaller passage area than other parts. Therefore, in the present invention, the connection part between the fuel vapor pipe and the exhaust gas recirculation pipe is throttled to increase the flow velocity of the connection part and generate a lower pressure at the connection part than the front and rear parts in the flow direction. An effect is obtained. Therefore, when the exhaust gas flows through the exhaust gas recirculation passage, the fuel vapor in the fuel vapor passage can be sucked into the exhaust gas recirculation passage and effectively delivered through the intake passage of the internal combustion engine.

  The invention described in claim 6 further includes an ejector provided at a connection portion between the fuel vapor pipe and the exhaust gas recirculation pipe in the exhaust gas recirculation passage. Therefore, in the present invention, when exhaust flows through the ejector, a venturi effect is obtained in which the flow rate of the throttle portion of the ejector is increased and a lower pressure is generated compared to the front and rear portions of the ejector in the flow direction. Therefore, when the exhaust gas flows through the ejector, the fuel vapor in the fuel vapor passage can be sucked into the exhaust gas recirculation passage and effectively delivered through the intake passage of the internal combustion engine.

Schematic which shows the gasoline engine system of the vehicle to which the fuel vapor processing apparatus by 1st Embodiment of this invention was applied. The flowchart figure which shows the control action of the fuel vapor processing apparatus by 1st Embodiment of this invention. Schematic which shows the gasoline engine system of the vehicle to which the fuel vapor processing apparatus by 2nd Embodiment of this invention was applied. Schematic which shows the gasoline engine system of the vehicle to which the fuel vapor processing apparatus by 3rd Embodiment of this invention was applied.

  Hereinafter, a fuel vapor processing apparatus according to a plurality of embodiments of the present invention will be described with reference to the drawings. Note that, in a plurality of embodiments, substantially the same components are denoted by the same reference numerals, and description thereof is omitted.

(First embodiment)
FIG. 1 shows a part of a gasoline engine system 1 of a vehicle to which a fuel vapor processing apparatus 5 according to a first embodiment of the present invention is applied. The gasoline engine system 1 includes an internal combustion engine (hereinafter referred to as “engine”) 2, a fuel tank 21, an intake system 3, an exhaust system 4, and a fuel vapor processing device 5. The fuel tank 21 contains gasoline used as fuel in the engine 2.

  The engine 2 is a well-known gasoline engine that generates driving force for a vehicle by using gasoline stored in a fuel tank 21 as fuel. The engine 2 puts a mixture of air and gasoline into a cylinder, compresses it with a piston, and ignites and burns it. Then, the force of the piston pushed by the combustion gas expanding in the cylinder is taken out as kinetic energy. This kinetic energy is used as the driving force of the vehicle. An intake system 3 and an exhaust system 4 are connected to the engine 2. The engine 2 has a plurality of cylinders, but only one is shown in FIG. 1 for convenience.

  The intake system 3 includes an intake pipe 31, an air cleaner 32, and a throttle valve device 33. The intake pipe 31 forms an intake passage 34 through which air sucked into the engine 2 flows. The end of the intake pipe 31 opposite to the engine 2 is open to the atmosphere. The air cleaner 32 is provided in the middle of the intake passage 34 and removes foreign matters in the air (intake air) taken into the intake pipe 31 from the atmosphere. The air that has passed through the air cleaner 32 is supplied into each cylinder of the engine 2 via the throttle valve device 33. The throttle valve device 33 is provided between the air cleaner 32 and the engine 2 in the intake passage 34, and adjusts the amount of air taken into the engine 2, that is, the intake amount by opening and closing the intake passage 34.

  The exhaust system 4 has an exhaust pipe 41. The exhaust pipe 41 forms an exhaust passage 42 through which the exhaust discharged from the engine 2 flows. The end of the exhaust pipe 41 opposite to the engine 2 is open to the atmosphere.

In the fuel tank 21, fuel vapor (evaporation) is generated by the vaporization of gasoline.
The fuel vapor processing device 5 sends fuel vapor generated in the fuel tank 21 to the engine 2 via the intake system 3 for processing. The fuel vapor treatment apparatus 5 includes an exhaust gas recirculation pipe 51, an EGR valve apparatus 52, a canister 53, a fuel vapor pipe 54, a purge valve apparatus 55, and an electronic control unit (hereinafter referred to as “ECU”) as a control unit. 56 etc.

  The exhaust gas recirculation pipe 51 has one end connected to the exhaust pipe 41 and the other end connected to the intake pipe 31. The exhaust gas recirculation pipe 51 forms an exhaust gas recirculation passage 511 inside. The exhaust gas recirculation pipe 51 recirculates part of the exhaust gas in the exhaust passage 42 to the intake air passage 34 via the exhaust gas recirculation passage 511.

The EGR valve device 52 adjusts an exhaust amount flowing through the exhaust gas recirculation passage 511 from the exhaust passage 42 side toward the intake passage 34 side, and includes an EGR valve 521 and an EGR valve actuator 522. The EGR valve 521 is provided in the middle of the exhaust gas recirculation passage 511 so that the exhaust gas recirculation passage 511 can be opened and closed. The EGR valve actuator 522 is an electromagnetic actuator and is electrically connected to the ECU 56. The EGR valve actuator 522 operates based on an electrical control signal output from the ECU 56, and drives the EGR valve 521 to open and close.
The exhaust gas recirculation passage 511 and the EGR valve device 52 are also part of components of a well-known EGR (Exhaust Gas Recirculation) device. The EGR device lowers the combustion temperature of the fuel in the engine 2 by returning a part of the exhaust gas in the exhaust passage 42 to the intake passage 34. Thereby, the fuel consumption improvement effect and the nitrogen oxide (NOx) reduction effect in exhaust gas are acquired.

  The canister 53 is provided in the middle of a fuel vapor passage 541 described later, and has an adsorbent 531 and an air passage 532. The adsorbent 531 is, for example, activated carbon, and adsorbs fuel vapor generated in the fuel tank 21. The atmospheric passage 532 has one end connected to the canister 53 and the other end open to the atmosphere. Note that the atmosphere passage 532 may be provided with a valve for controlling the communication state of the canister 53 to the atmosphere.

The fuel vapor pipe 54 has one end connected to the fuel tank 21 and the other end connected to the exhaust gas recirculation pipe 51. The fuel vapor pipe 54 forms a fuel vapor passage 541 on the inner side. The fuel vapor pipe 54 guides the fuel vapor desorbed from the canister 53 to the exhaust gas recirculation passage 511 via the fuel vapor passage 541.
The other end of the fuel vapor pipe 54 is connected to the intake pipe 31 side of the exhaust gas recirculation pipe 51 with respect to the EGR valve 521. The other end of the fuel vapor pipe 54 is provided so as to protrude into the exhaust gas recirculation passage 511. The opening at the other end of the fuel vapor pipe 54 may be anywhere as long as it is located inside the exhaust gas recirculation passage 511, but in this embodiment, for example, it is located near the center of the exhaust gas recirculation passage 511.

  The purge valve device 55 controls the amount of air-fuel mixture including fuel vapor that flows through the fuel vapor passage 541 from the canister 53 side toward the exhaust gas recirculation passage 511, and includes a purge valve 551 and a purge valve actuator 552. ing. The purge valve 551 is provided in the middle of the fuel vapor passage 541 so that the fuel vapor passage 541 can be opened and closed. The purge valve actuator 552 is an electromagnetic actuator and is electrically connected to the ECU 56. The purge valve actuator 552 operates based on an electrical control signal output from the ECU 56, and drives the purge valve 551 to open and close.

  The ECU 56 includes a microcomputer having a CPU, a ROM, a RAM, and the like (not shown). The ECU 56 is electrically connected to an engine speed sensor 561, a cooling water temperature sensor 562, a throttle opening sensor 563, an accelerator opening sensor 564, a tank pressure sensor 565, and an intake pipe pressure sensor 566. Signals output from the sensors 561 to 566 are input. The ECU 56 controls each part of the fuel vapor processing apparatus 5 in accordance with a predetermined control program recorded in the ROM based on these input various signals. Specifically, the ECU 56 controls the opening of each of the EGR valve 521 and the purge valve 551, that is, the EGR valve opening and the purge valve opening, by controlling the operations of the EGR valve actuator 522 and the purge valve actuator 552. .

The engine rotation speed sensor 561 detects the rotation speed of the crankshaft of the engine 2, that is, the engine rotation speed. The engine speed sensor 561 outputs the detected engine speed to the ECU 56 as an electrical signal.
The cooling water temperature sensor 562 is provided in the cooling water passage of the engine block of the engine 2 and detects the temperature of the cooling water flowing through the cooling water passage, that is, the cooling water temperature. The coolant temperature sensor 562 outputs the detected coolant temperature to the ECU 56 as an electrical signal.

The throttle opening sensor 563 is provided in the throttle valve device 33 and detects the opening of the throttle valve device 33, that is, the throttle opening. The throttle opening sensor 563 outputs the detected throttle opening to the ECU 56 as an electrical signal.
The accelerator opening sensor 564 is provided on the rotating shaft of the accelerator pedal 567 and detects the accelerator opening corresponding to the operation amount of the accelerator pedal 567. The accelerator opening sensor 564 outputs the detected accelerator opening to the ECU 56 as an electrical signal.

The tank internal pressure sensor 565 is provided in the fuel tank 21 and detects the pressure in the fuel tank 21, that is, the tank internal pressure. The tank internal pressure sensor 565 outputs the detected tank internal pressure to the ECU 56 as an electrical signal.
The intake pipe pressure sensor 566 detects the pressure in the intake pipe 31, that is, the intake pipe internal pressure. The intake pipe internal pressure sensor 566 outputs the detected intake pipe internal pressure to the ECU 56 as an electric signal.
The ECU 56 and the EGR valve device 52 constitute EGR valve opening degree control means for controlling the EGR valve opening degree. The ECU 56 and the purge valve device 55 constitute purge valve opening control means for controlling the purge valve opening.

When the EGR valve 521 and the purge valve 551 are open, the fuel vapor treatment device 5 causes the fuel vapor in the fuel vapor passage 541 to flow into the exhaust gas recirculation passage 511 due to the negative pressure generated by exhaust gas flowing through the exhaust gas recirculation passage 511 The fuel vapor is sucked and the fuel vapor is guided to the intake passage 34 by the flow of the exhaust gas in the exhaust gas recirculation passage 511 and sent to the engine 2.
Hereinafter, the function of the ECU 56 for performing the delivery of the fuel vapor by the fuel vapor processing apparatus 5 will be described.

  The ECU 56 adjusts the EGR valve opening, for example, between 0 and 20% based on the load state of the engine 2. Specifically, the ECU 56 determines whether or not the condition for exhaust gas recirculation, that is, the EGR execution condition is satisfied, based on the load state of the engine 2. When the EGR execution condition is satisfied, the EGR valve opening is adjusted to open the EGR valve 521. When the EGR execution condition is not satisfied, the EGR valve opening is adjusted to adjust the EGR valve opening. 521 is closed.

Specifically, the ECU 56 estimates whether the engine 2 is in a low load state, a medium load state, or a high load state based on the engine rotation speed, the coolant temperature, the throttle opening degree, and the accelerator opening degree. . In the present embodiment, for example, whether the engine speed is equal to or higher than a predetermined first predetermined value, whether the coolant temperature is equal to or higher than a predetermined second predetermined value, or whether the throttle opening is equal to or higher than a predetermined third predetermined value. Alternatively, when the accelerator opening is equal to or greater than a predetermined fourth predetermined value, it is estimated that the engine 2 is in a high load state, and in other cases, the engine 2 is in a low load state or a medium load state. It is estimated to be. Here, the ECU 56 and the sensors 561 to 564 constitute load state estimation means for estimating the load state of the engine.
When the engine 2 is in the low load state or the medium load state, it is determined that the EGR execution condition is satisfied. Further, when the engine 2 is in a high load state, it is determined that the EGR execution condition is not satisfied. The first predetermined value to the fourth predetermined value are obtained experimentally and stored in advance in the ROM, for example. Here, the ECU 56 functions as an EGR execution determination unit that determines whether a condition for exhaust gas recirculation, that is, an EGR execution condition is satisfied.

  When the ECU 56 estimates that the engine 2 is in the low load state or the medium load state, the EGR is based on the estimated load level of the engine 2 from, for example, a map or an arithmetic expression stored in advance in the ROM. Determine the valve opening. Further, when it is estimated that the engine 2 is in a high load state, the ECU 56 adjusts the EGR valve opening degree to approximately 0 (zero). Here, the ECU 56 functions as an EGR valve opening degree determining means for determining the EGR valve opening degree according to the load state of the engine 2.

The ECU 56 opens the EGR valve 521 when the engine 2 is at a low load or a medium load, and determines whether a condition for purging fuel vapor, that is, an evaporative purge execution condition is satisfied. Specifically, the ECU 56 determines that the evaporation purge execution condition is satisfied, for example, when the tank internal pressure is equal to or higher than a predetermined fifth predetermined value. Further, when the tank internal pressure is smaller than a predetermined fifth predetermined value, it is determined that the evaporation purge execution condition is not satisfied. The fifth predetermined value is obtained experimentally, for example, and stored in advance in the ROM. Here, the ECU 56 functions as an evaporation purge execution determining unit that determines whether or not the evaporation purge execution condition is satisfied.
Then, the ECU 56 opens the purge valve 551 when the evaporation purge execution condition is satisfied. By opening the purge valve 551, the air-fuel mixture in the fuel vapor passage 541 containing fuel vapor is guided to the intake passage 34 by the exhaust gas flow in the exhaust gas recirculation passage 511, and is sent to the engine 2. In other words, the fuel vapor adsorbed by the adsorbent 531 is purged into the intake passage 34 by opening the purge valve 551. Here, the ECU 56 and the purge valve device 55 constitute evaporation purge execution means for performing evaporation purge.

  Prior to the opening of the purge valve 551, the ECU 56 determines the purge valve opening based on the intake pipe internal pressure. Specifically, the ECU 56 determines the purge valve opening based on the intake pipe internal pressure from, for example, a map or an arithmetic expression stored in advance in the ROM. For example, the ECU 56 increases the opening degree of the purge valve as the intake pipe internal pressure increases to the negative side (minus side). Here, the ECU 56 functions as a purge valve opening determining means that determines the purge valve opening according to the intake pipe internal pressure.

  The ECU 56 closes the EGR valve 521 when the engine 2 is at a high load, and determines whether an evaporation purge execution condition is satisfied. When the evaporation purge execution condition is satisfied, the purge valve 551 is opened. By opening the purge valve 551, the air-fuel mixture in the fuel vapor passage 541 is sucked into the intake passage 34 by the negative pressure generated by the intake air flowing through the intake passage 34 and sent to the engine 2. In other words, the fuel vapor adsorbed by the adsorbent 531 is purged into the intake passage 34 by opening the purge valve 551.

  Next, the operation of the ECU 56 will be described with reference to FIG. FIG. 2 shows a processing flow related to the control operation of the fuel vapor processing apparatus 5 by the ECU 56. A series of processes shown in FIG. 2 is started immediately after the engine 2 is started.

In S101, the ECU 56 determines whether or not an EGR execution condition is satisfied. The ECU 56 determines that the EGR execution condition is satisfied when the engine 2 is low load or medium load, and determines that the EGR execution condition is not satisfied when the engine 2 is high load. For example, the ECU 56 determines whether the engine speed is equal to or higher than a predetermined first predetermined value, whether the coolant temperature is equal to or higher than a predetermined second predetermined value, or whether the throttle opening is equal to or higher than a predetermined third predetermined value. When the accelerator opening is equal to or greater than a predetermined fourth predetermined value, it is determined that the engine 2 is in a high load state, and in other cases, it is determined that the engine 2 is in a low load state or a medium load state. To do.
If the EGR execution condition is satisfied (S101: YES), the process proceeds to S102. On the other hand, when the EGR execution condition is not satisfied (S101: NO), the process proceeds to S105.

In S102, the ECU 56 turns on the EGR execution flag.
In S103, the ECU 56 determines the EGR valve opening. Specifically, the ECU 56 determines the EGR valve opening based on the estimated load degree of the engine 2 from, for example, a map or an arithmetic expression stored in advance in the ROM.
In S104, the ECU 56 opens the EGR valve 521 in accordance with the EGR valve opening determined in S103.

In S105, the ECU 56 determines whether or not an evaporation purge execution condition is satisfied. For example, the ECU 56 determines that the evaporation purge execution condition is satisfied when the tank internal pressure is equal to or higher than a predetermined fifth predetermined value. Further, when the tank internal pressure is smaller than a predetermined fifth predetermined value, it is determined that the evaporation purge execution condition is not satisfied.
If the evaporation purge execution condition is satisfied (S105: YES), the process proceeds to S107. On the other hand, when the evaporation purge execution condition is not satisfied (S105: NO), the process proceeds to S125.

  In S106, the ECU 56 determines whether or not the evaporation purge execution condition is satisfied. This criterion is the same as S105. If the evaporation purge execution condition is satisfied (S106: YES), the process proceeds to S107. On the other hand, when the evaporation purge execution condition is not satisfied (S106: NO), the process proceeds to S122.

  In S107, the ECU 56 determines whether or not the EGR execution flag is ON. If the EGR execution flag is ON (S107: YES), the process proceeds to S110. On the other hand, when the EGR execution flag is not ON, that is, when the EGR execution flag is OFF (S107: NO), the process proceeds to S108.

In S108, the ECU 56 determines whether or not an EGR execution condition is satisfied. This criterion is the same as S101. If the EGR execution condition is satisfied (S108: YES), the process proceeds to S109. On the other hand, when the EGR execution condition is not satisfied (S108: NO), the process proceeds to S114.
In S109, the ECU 56 turns on the EGR execution flag.

In S110, the ECU 56 determines the EGR valve opening degree. The determination criteria for the EGR valve opening are the same as in S103.
In S111, the ECU 56 opens the EGR valve 521 in accordance with the EGR valve opening determined in S110.

In S112, the ECU 56 determines the purge valve opening from the EGR valve opening. Specifically, the ECU 56 determines the purge valve opening based on the EGR valve opening from, for example, a map or an arithmetic expression stored in advance in the ROM. For example, the ECU 56 increases the purge valve opening as the EGR valve opening increases.
In S113, the ECU 56 opens the purge valve 551 in accordance with the purge valve opening determined in S112.

In S114, the ECU 56 determines the purge valve opening based on the intake pipe internal pressure. Specifically, the ECU 56 determines the purge valve opening based on the intake pipe internal pressure from, for example, a map or an arithmetic expression stored in advance in the ROM. For example, the ECU 56 increases the opening degree of the purge valve as the intake pipe internal pressure increases to the negative side (minus side).
In S115, the ECU 56 opens the purge valve 551 in accordance with the purge valve opening determined in S114.

  In S116, the ECU 56 determines whether or not the EGR execution flag is ON. If the EGR execution flag is ON (S116: YES), the process proceeds to S117. On the other hand, when the EGR execution flag is not ON, that is, when the EGR execution flag is OFF (S116: NO), the process proceeds to S120.

In S117, the ECU 56 determines whether or not the EGR stop condition is satisfied, that is, whether or not the EGR execution condition is not satisfied. The ECU 56 determines that the EGR stop condition is satisfied when the engine 2 is at a high load, and determines that the EGR stop condition is not satisfied when the engine 2 is at a low load or a medium load.
If the EGR stop condition is satisfied (S117: YES), the process proceeds to S118. On the other hand, when the EGR stop condition is not satisfied (S117: NO), the process proceeds to S120.

In S118, the ECU 56 sets the EGR execution flag to OFF.
In S119, the ECU 56 closes the EGR valve 521.

In S120, the ECU 56 determines whether or not an evaporation purge stop condition is satisfied. For example, the ECU 56 determines that the evaporation purge stop condition is satisfied when the tank internal pressure is smaller than a predetermined fifth predetermined value. Further, when the tank internal pressure is equal to or higher than a predetermined fifth predetermined value, it is determined that the evaporation purge stop condition is not satisfied.
If the evaporation purge stop condition is satisfied (S120: YES), the process proceeds to S121. On the other hand, if the evaporation purge stop condition is not satisfied (S120: NO), the process proceeds to S107.
In S121, the ECU 56 closes the purge valve 551.

  In S122, the ECU 56 determines whether or not the EGR stop condition is satisfied, that is, whether or not the EGR execution condition is not satisfied. This criterion is the same as in S117. If the EGR stop condition is satisfied (S122: YES), the process proceeds to S123. On the other hand, when the EGR stop condition is not satisfied (S122: NO), the process proceeds to S103.

In S123, the ECU 56 sets the EGR execution flag to OFF.
In S124, the ECU 56 closes the EGR valve 521.
In S125, the ECU 56 determines whether or not the engine 2 is stopped based on, for example, an output control signal of the engine 2 or the like. When the engine 2 is stopped (S125: YES), the ECU 56 exits a series of routines shown in FIG. On the other hand, when the engine 2 is not stopped (S125: NO), the process proceeds to S101.

  As described above, in this embodiment, when the EGR valve 521 and the purge valve 551 are open, the fuel vapor in the fuel vapor passage 541 is exhausted by the negative pressure generated by the exhaust gas flowing through the exhaust gas recirculation passage 511. The refrigerant is sucked into the recirculation passage 511, and the fuel vapor is guided to the intake passage 34 by the flow of the exhaust gas in the exhaust recirculation passage 511 and sent to the engine 2. Moreover, in this embodiment, the pressure accumulation tank which was essential in the conventional fuel vapor processing apparatus of the type which sends out fuel vapor using the accumulated compressed air is unnecessary, and the enlargement of the fuel vapor processing apparatus is suppressed. can do. Further, in the present embodiment, when the engine 2 is in operation, the fuel vapor delivery action using the exhaust gas is obtained. Therefore, it is possible to avoid a situation in which the fuel vapor delivery action can be obtained only while compressed air is present in the pressure accumulation tank, as in the conventional fuel vapor processing apparatus. Therefore, it is possible to obtain a fuel vapor processing apparatus 5 that is small in size and can effectively send fuel vapor to the intake passage 34.

  In the present embodiment, the ECU 56 controls the operation of the EGR valve actuator 522 and the purge valve actuator 552 based on the load state of the engine 2, so that the exhaust flow in the exhaust recirculation passage 511 or the negative pressure in the intake passage 34 The fuel vapor is guided to the intake passage 34 and sent to the engine 2. Therefore, the fuel vapor can be effectively delivered to the intake passage 34.

  In the present embodiment, the other end of the fuel vapor pipe 54 is connected to the intake pipe 31 side of the exhaust gas recirculation pipe 51 with respect to the EGR valve 521. Therefore, even when the EGR valve 521 is closed when the engine 2 is at a high load, the fuel vapor in the fuel vapor pipe 54 can be sent to the intake passage 34 via the exhaust gas recirculation pipe 51.

  In the present embodiment, the fuel vapor pipe 54 is provided so that the other end protrudes into the exhaust gas recirculation passage 511. Therefore, when the exhaust gas flows through the exhaust gas recirculation passage 511, the fuel vapor in the fuel vapor passage 541 can be sucked into the exhaust gas recirculation passage 511 and effectively sent out by the intake air passage 34. The opening at the other end of the fuel vapor pipe 54 is located near the center of the exhaust gas recirculation passage 511. For this reason, the opening at the other end of the fuel vapor pipe 54 is located at a portion where the flow velocity is relatively fast in the exhaust gas recirculation passage 511, so that the fuel vapor in the fuel vapor passage 541 is effectively sent out by the exhaust gas recirculation passage 511. be able to.

(Second Embodiment)
The part of the gasoline engine system 1 of the vehicle to which the fuel vapor processing apparatus of the second embodiment of the present invention is applied is shown.

  In the second embodiment, the exhaust gas recirculation pipe 51 has a throttle portion 60 at a connection site with the fuel vapor pipe 54. The throttle portion 60 forms a throttle passage 601 that forms part of the exhaust gas recirculation passage 511. This throttle passage 601 has a portion in which the passage area continuously decreases and a portion in which the passage area continuously increases in the flow direction of the exhaust gas recirculation passage 511 from the exhaust pipe 41 side toward the intake pipe 31 side. ing. The fuel vapor pipe 54 is connected to a portion of the throttle portion 60 having the smallest passage area. As a result, the exhaust gas recirculation passage 511 is formed such that the connection area between the fuel vapor pipe 54 and the exhaust gas recirculation pipe 51 has a smaller passage area than other parts, that is, the front and rear parts of the exhaust gas recirculation path 511 in the flow direction. .

  The configuration of the fuel vapor processing apparatus of this embodiment is the same as that of the first embodiment, except that the shape of the connection portion between the fuel vapor pipe 54 and the exhaust gas recirculation pipe 51 is different. In this embodiment, when the EGR valve 521 and the purge valve 551 are open, the fuel vapor in the fuel vapor passage 541 is sucked into the exhaust recirculation passage 511 by the negative pressure generated by the exhaust gas flowing through the exhaust recirculation passage 511. Then, the fuel vapor is guided to the intake passage 34 by the flow of the exhaust gas in the exhaust gas recirculation passage 511 and sent to the engine 2. Therefore, also in the present embodiment, as in the first embodiment, it is possible to obtain a fuel vapor processing apparatus that is small in size and capable of effectively sending fuel vapor to the intake passage 34.

  Further, in the present embodiment, the exhaust gas recirculation passage 511 is formed such that the connection area between the fuel vapor pipe 54 and the exhaust gas recirculation pipe 51 has a smaller passage area than other areas. Therefore, the connection part between the fuel vapor pipe 54 and the exhaust gas recirculation pipe 51 is narrowed, thereby increasing the flow velocity of the connection part and generating a lower pressure compared to the front and rear parts of the connection part in the flow direction. can get. Therefore, when the exhaust gas flows through the exhaust gas recirculation passage 511, the fuel vapor in the fuel vapor passage 541 can be sucked into the exhaust gas recirculation passage 511 and effectively sent out by the intake air passage 34.

(Third embodiment)
The part of the gasoline engine system 1 of the vehicle to which the fuel vapor processing apparatus of the third embodiment of the present invention is applied is shown.

  In the third embodiment, the exhaust gas recirculation pipe 51 has an ejector 70 at a connection site with the fuel vapor pipe 54. The ejector 70 may be of any known type, but in this embodiment, the first port 701 connected to the exhaust pipe 41 side of the exhaust gas recirculation passage 511 and the exhaust gas recirculation passage 511. The throttle passage 703 includes a second port 702 connected to the intake pipe 31 side. The throttle passage 703 has a portion in which the passage area continuously decreases in the flow direction from the first port 701 to the second port 702 and a portion in which the passage area continuously increases. The other end of the fuel vapor pipe 54 is connected via a third port 705 to a fuel vapor supply chamber 704 formed to protrude outward from a portion of the throttle passage 703 where the passage area continuously increases. .

  The configuration of the fuel vapor processing apparatus of this embodiment is the same as that of the first embodiment except that an ejector 70 is provided at a connection portion between the fuel vapor pipe 54 and the exhaust gas recirculation pipe 51. In this embodiment, when the EGR valve 521 and the purge valve 551 are open, the fuel vapor in the fuel vapor passage 541 is exhausted through the exhaust gas recirculation passage 511 due to the negative pressure generated in the ejector 70 when exhaust flows through the exhaust gas recirculation passage 511. The fuel vapor is guided to the intake passage 34 by the exhaust flow of the exhaust gas recirculation passage 511 and sent to the engine 2. Therefore, according to the present embodiment, as in the first embodiment, the fuel vapor processing device 9 that is small in size and capable of effectively sending fuel vapor to the intake passage 34 can be obtained.

  Further, in the present embodiment, an ejector 70 provided at a connection portion of the exhaust gas recirculation passage 511 with the fuel vapor pipe 54 is further provided. Therefore, when exhaust flows through the ejector 70, a venturi effect is obtained in which the flow velocity of the throttle passage 703 of the ejector 70 is increased and a pressure lower than that of the front and rear portions of the ejector 70 is generated in the throttle passage 703. Therefore, when the exhaust gas flows through the ejector 70, the fuel vapor in the fuel vapor passage 541 can be sucked into the exhaust gas recirculation passage 511 and effectively sent out through the intake passage 34.

(Other embodiments)
In the first embodiment, the other end of the fuel vapor pipe 54 is provided so as to protrude into the exhaust gas recirculation passage 511. In the second embodiment, the exhaust gas recirculation passage 511 is formed so that the connection area between the fuel vapor pipe 54 and the exhaust gas recirculation pipe 51 has a smaller passage area than other areas. Further, in the third embodiment, the exhaust gas recirculation pipe 51 is provided with the ejector 70 at the connection portion with the fuel vapor pipe 54. On the other hand, in another embodiment of the present invention, the other end of the fuel vapor pipe may be provided so as to open to the inner wall surface of the exhaust gas recirculation passage.

  In the above-described embodiment, the other end of the fuel vapor pipe 54 is connected to the intake pipe 31 side of the exhaust gas recirculation pipe 51 with respect to the EGR valve 521. On the other hand, in another embodiment of the present invention, the other end of the fuel vapor pipe may be connected to the exhaust pipe side with respect to the EGR valve in the exhaust gas recirculation pipe.

  In the above-described embodiment, the EGR valve 521 is opened when the engine 2 is at a low load or a medium load, and is closed when the engine 2 is at a high load. In contrast, in another embodiment of the present invention, the EGR valve may be opened when the engine is lightly loaded while being closed when the engine is medium or heavily loaded. Good. Further, in another embodiment of the present invention, the EGR valve may be driven to open and close regardless of the load state of the engine.

  In the above-described embodiment, the ECU 56 estimates the load state of the engine 2 based on the engine rotation speed, the coolant temperature, the throttle opening, and the accelerator opening. On the other hand, in another embodiment of the present invention, the ECU 56 may estimate the load state of the engine based on at least one of the engine speed, the coolant temperature, the throttle opening, and the accelerator opening. The engine load state may be estimated based on other values.

  In the above-described embodiment, the ECU 56 determines whether or not the evaporation purge execution condition is satisfied based on the tank internal pressure. On the other hand, in another embodiment of the present invention, whether or not the evaporation purge execution condition is satisfied may be determined based on a value other than the tank internal pressure. Specifically, for example, whether or not the evaporation purge execution condition is satisfied may be determined based on the fuel vapor amount and fuel vapor concentration in the canister, or the pressure, flow rate, and flow velocity in the fuel vapor passage.

  In the embodiment described above, the canister 53 is provided in the fuel vapor passage 541. On the other hand, in another embodiment of the present invention, no canister may be provided in the fuel vapor passage.

  In the above-described embodiment, the fuel vapor processing apparatus is applied to a gasoline engine system. On the other hand, in other embodiment of this invention, it is good also as being applied to other engine systems, such as a diesel engine system, for example.

  In the above-described embodiment, the fuel vapor processing apparatus is applied to a naturally aspirated gasoline engine system. On the other hand, in another embodiment of the present invention, for example, the present invention may be applied to a supercharged intake type engine system including a supercharger. When the fuel vapor processing device is applied to a supercharged intake type engine system, the exhaust gas recirculation pipe may constitute a part of the low pressure EGR device or the high pressure EGR device.

  Thus, the present invention is not limited to the above-described embodiment, and can be applied to various forms without departing from the gist thereof.

2 ... Engine (internal combustion engine)
DESCRIPTION OF SYMBOLS 5 ... Fuel vapor processing apparatus 21 ... Fuel tank 31 ... Intake pipe 34 ... Intake passage 41 ... Exhaust pipe 42 ... Exhaust passage 51 ... Exhaust recirculation pipe 54 ... Fuel Steam pipe 511 ... exhaust gas recirculation passage 521 ... EGR valve 541 ... fuel vapor passage 551 ... purge valve

Claims (6)

A fuel vapor processing apparatus for sending and processing fuel vapor generated in a fuel tank to an internal combustion engine,
One end is connected to the exhaust pipe of the internal combustion engine, the other end is connected to the intake pipe of the internal combustion engine, and the exhaust pipe exhaust is exhausted through the exhaust gas recirculation passage formed inside. An exhaust gas recirculation pipe that can recirculate to the intake passage of
A fuel vapor pipe having one end connected to the fuel tank, the other end connected to the exhaust gas recirculation pipe, and leading the fuel vapor to the exhaust gas recirculation path via a fuel vapor path formed inside;
An EGR valve provided to open and close the exhaust gas recirculation passage;
A purge valve provided to open and close the fuel vapor passage,
When the EGR valve and the purge valve are open, the fuel vapor in the fuel vapor path is sucked into the exhaust gas recirculation path by the negative pressure generated by the exhaust gas flowing through the exhaust gas recirculation path. A fuel vapor processing apparatus, wherein the fuel vapor is guided to the intake passage by the flow of exhaust in the passage and is sent to the internal combustion engine. An EGR valve actuator for opening and closing the EGR valve;
A purge valve actuator for opening and closing the purge valve;
A controller capable of adjusting the opening degree of each of the EGR valve and the purge valve by controlling the operation of the EGR valve actuator and the purge valve actuator;
The control unit adjusts the opening of the EGR valve based on a load state of the internal combustion engine,
When the internal combustion engine is at low load or medium load, the fuel vapor is led to the intake passage by the flow of exhaust gas in the exhaust gas recirculation passage by opening the EGR valve and opening the purge valve. To
When the internal combustion engine is at a high load, by closing the EGR valve and opening the purge valve, the fuel vapor is sucked into the intake passage by the negative pressure generated by the intake air flowing through the intake passage. The fuel vapor processing apparatus according to claim 1, wherein the fuel vapor processing apparatus delivers the fuel to the internal combustion engine.   3. The fuel vapor processing apparatus according to claim 1, wherein the other end of the fuel vapor pipe is connected to the intake pipe side of the exhaust gas recirculation pipe with respect to the EGR valve.   The fuel vapor processing apparatus according to any one of claims 1 to 3, wherein the fuel vapor pipe is provided so that the other end protrudes into the exhaust gas recirculation passage.   The exhaust gas recirculation passage is formed so that a connection area between the fuel vapor pipe and the exhaust gas recirculation pipe is smaller than other areas. A fuel vapor processing apparatus according to claim 1.   The fuel vapor processing apparatus according to any one of claims 1 to 4, further comprising an ejector provided at a connection portion between the fuel vapor pipe and the exhaust gas recirculation pipe in the exhaust gas recirculation passage.

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