JP2017067003A - Evaporation fuel treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an evaporation fuel treatment device capable of preventing the HAKA of an evaporation fuel when pressure in a fuel tank is lowered, without enlarging a canister.SOLUTION: An evaporation fuel treatment device is equipped with a pressure sensor 27 which detects pressure in a fuel tank 5; an airtight valve 29 provided between the fuel tank 5 and a purge passage; a canister 7 for absorbing an evaporation fuel, which is equipped with an atmosphere opening valve 25 introducing air into the canister 7; a pressurizing pump 9 connected to a downstream side of the canister 7; and a purge valve 11 provided on a downstream side of the pressurizing pump 9 on the purge passage. When pressure detected by the pressure sensor 27 becomes a predetermined value or more, during the operation of an engine, the purge valve 11 and the atmosphere opening valve 25 are opened, and the pressurizing pump 9 is actuated. Then, the airtight valve 29 is opened.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an evaporated fuel processing apparatus, and more particularly to an evaporated fuel processing apparatus applied to a closed tank system.

  2. Description of the Related Art Conventionally, there is known an evaporative fuel processing apparatus applied to a closed tank system including a canister for accumulating evaporative fuel generated when fuel is supplied to a fuel tank.

  In the closed tank system, a purge passage different from the fuel supply system to the engine is provided between the fuel tank and the engine intake pipe on the upstream side of the engine, and the evaporated fuel generated in the fuel tank at the time of fueling is temporarily Accumulate in the canister on the purge passage. Then, at a predetermined purge timing, a negative pressure is generated in the canister by operating a pump provided between the canister and the engine intake pipe on the purge passage, whereby the evaporation accumulated in the canister Fuel is supplied to the engine intake pipe. In the sealed tank system, the sealed valve provided between the fuel tank and the purge passage is closed so that the evaporated fuel in the fuel tank does not flow into the engine intake pipe except during the purge timing and refueling. As an evaporative fuel processing apparatus in such a closed tank system, the apparatus described in Patent Document 1 is known.

JP 2013-194602 A

  Generally, in a closed tank system, since the closed valve between the fuel tank and the purge passage is closed except during refueling, for example, the fuel is partially vaporized due to temperature rise in the fuel tank, and the fuel tank The internal pressure may increase. Therefore, in order to suppress an increase in the pressure in the fuel tank, it is necessary to reduce the pressure in the fuel tank at regular intervals. In this case, it is conceivable that when the pressure in the fuel tank becomes equal to or higher than a certain value, the sealing valve is successively opened to release the evaporated fuel in the fuel tank from the fuel tank.

  However, if the sealing valve is simply opened and closed according to the pressure in the fuel tank, a large amount of the evaporated fuel in the fuel tank may be adsorbed by the adsorbent in the canister such as activated carbon. As a result, a large amount of evaporated fuel is adsorbed by the adsorbent in the canister. When the evaporated fuel remaining in the purge passage is adsorbed by the canister, when the canister originally wants to adsorb the evaporated fuel, the canister's adsorbable capacity becomes insufficient, and the evaporated fuel breaks through the canister. There was a problem that. In order to solve this problem, it is necessary to increase the size of the canister and increase the capacity of adsorption.

  Therefore, the present invention has been made to solve the above-described problems, and can prevent breakthrough of evaporated fuel when reducing the pressure in the fuel tank without increasing the size of the canister. An object of the present invention is to provide a fuel vapor processing apparatus.

  In order to solve the above problems, the present invention provides a purge passage extending from a fuel tank toward an engine intake pipe, a tank internal pressure sensor for detecting a pressure in the fuel tank, and a gap between the fuel tank and the purge passage. A canister for receiving evaporative fuel from a fuel tank and adsorbing the evaporative fuel, the canister being provided on the purge passage on the downstream side of the seal valve, and having air in the canister A canister having an atmosphere release valve for introducing the pressure, a pressure pump connected to the downstream side of the canister on the purge passage, and a downstream side of the pressure pump on the purge passage. An evaporative fuel processing apparatus comprising a purge valve, wherein the pressure detected by the tank internal pressure sensor is equal to or greater than a predetermined value. When Tsu, during engine operation, the purge valve, and then the air release valve in the open state, and the actuates the pressurizing pump, then, is characterized in that, to open the closed valve.

  According to the present invention configured as described above, when the pressure detected by the tank internal pressure sensor becomes equal to or higher than a predetermined value during engine operation, the purge valve and the air release valve are opened, and the pressure pump Can be activated. Thereby, a negative pressure is generated on the downstream side of the pressurizing pump, and an airflow is generated from the air release valve through the canister to the pressurizing pump. Then, after the air flow is generated, the hermetic valve is opened to generate an air flow from the fuel tank to the pressure pump through the canister. The evaporated fuel in the fuel tank is sucked from the fuel tank and flows toward the canister. When the evaporated fuel enters the canister, the evaporated fuel flows from the canister toward the pressurization pump by the airflow flowing from the atmosphere release valve toward the pressurization pump. At this time, the evaporated fuel that has entered the canister is immediately discharged from the canister without contacting the adsorbent of the canister. Therefore, when the pressure in the fuel tank is reduced, the evaporated fuel does not come into contact with the adsorbent in the canister, and the evaporated fuel is not adsorbed by the adsorbent. Thus, when the pressure in the fuel tank is lowered, the evaporated fuel can be prevented from contacting the adsorbent, and the amount of evaporated fuel accumulated in the canister can be prevented from increasing.

  In the present invention, preferably, a flow sensor for measuring an air flow rate in the purge passage after the pressurization pump is started is provided between the air introduction port and the pressurization pump, and is measured by the flow rate sensor. The sealed valve is opened when the measured value is equal to or greater than a predetermined value.

  According to the present invention configured as described above, after starting the pressurizing pump, after a sufficient air flow is generated, the sealing valve is opened, the evaporated fuel in the fuel tank is sucked from the fuel tank, and passed through the canister. It can flow toward the downstream side of the purge passage. Thereby, it is possible to prevent the evaporated fuel from coming into contact with the adsorbent of the canister more reliably.

  In the present invention, preferably, the purge valve and the air release valve are opened, the pressurizing pump is operated, and then the sealing valve is opened when the engine is started.

  Further, in the present invention, preferably, the control for opening the purge valve and the atmospheric release valve and operating the pressurizing pump and then opening the sealing valve does not perform the purge control of the canister. Sometimes do.

  As described above, according to the present invention, when the pressure in the fuel tank is reduced without increasing the size of the canister, breakthrough of the evaporated fuel can be prevented.

It is a block diagram which shows the evaporative fuel processing apparatus by embodiment of this invention. It is a flowchart which shows operation | movement of the evaporative fuel processing apparatus by embodiment of this invention.

  Hereinafter, an evaporated fuel processing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a fuel vapor processing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the evaporated fuel processing apparatus is configured to supply evaporated fuel generated in a fuel tank 5 to an engine intake pipe 3 connected to the engine 1. The evaporative fuel processing device includes a purge passage extending from the fuel tank 5 toward the engine intake pipe 3. On the purge passage, a canister 7, a pressurizing pump 9, and a purge valve 11 are provided from the upstream side. In this specification, “upstream side” and “downstream side” are defined based on the direction in which the evaporated fuel flows in the purge passage unless otherwise specified. The fuel tank 5 side in the purge passage extending from the fuel tank 5 as a starting point is referred to as “downstream side”, and the engine intake pipe 3 side in the purge passage terminating at the engine intake pipe 3 is referred to.

  The canister 7 is connected to the fuel tank 5 and adsorbs and accumulates the evaporated fuel flowing from the fuel tank 5. The canister 7 includes a first cylindrical container 7a and a second cylindrical body 7b that accommodate an adsorbent such as activated carbon, and is arranged at one end of the first cylindrical container 7a and the second cylindrical container 7b. The part is connected so that gas can go back and forth between the first cylindrical container 7a and the second cylindrical container 7b. The other end portion of the first cylindrical container 7a receives the evaporated fuel from the fuel tank 5, and allows the evaporated fuel accumulated in the canister 7 to flow toward the downstream side. The other end of the second cylindrical container 7 b is connected to a fresh air supply pipe 13 for supplying fresh air to the canister 7.

  Further, the side of the canister that is connected to the fresh air supply pipe 13 of the first cylindrical container 7a and the side that receives and discharges the evaporated fuel of the second cylindrical container 7b are not filled with the adsorbent. A space is formed. When the pressure in the fuel tank 5 is lowered as will be described later, the airflow flowing from the fuel tank 5 into the second cylindrical container 7b passes through the space where the adsorbent does not exist and passes through the purge passage. It flows toward the downstream side.

  The pressure pump 9 has an inlet connected to the canister 7 and an outlet connected to the purge valve 11. The pressure pump 9 generates a negative pressure on the upstream side of the pressure pump 9 in the purge passage under the control of the ECU 15 during the purge to supply the evaporated fuel to the engine intake pipe 3. A positive pressure is generated downstream. Thereby, the evaporated fuel adsorbed in the canister 7 is sucked and can flow toward the downstream side of the canister 7.

  The purge valve 11 is provided immediately upstream of the engine intake pipe 3 and adjusts the supply amount of the evaporated fuel that has passed through the purge passage to the engine intake pipe 3. The opening and closing of the purge valve 11 is controlled by the ECU 15. When the purge valve 11 is open, the canister 7, the pressurizing pump 9, and the engine intake pipe 3 are connected, and when the purge valve 11 is closed, The connection between the canister 7 and the pressurizing pump 9 and the engine intake pipe 3 is cut off.

  Between the fuel tank 5 and the first cylindrical container 7a of the canister 7, there is provided an evaporated fuel supply pipe 17 for supplying the evaporated fuel generated in the fuel tank 5 into the first cylindrical container 7a. . The evaporated fuel supplied from the evaporated fuel supply pipe 17 to the first cylindrical container 7 a is adsorbed by the adsorbent in the canister 7 and accumulated in the canister 7. In addition, an accumulated fuel supply pipe 19 that supplies evaporated fuel accumulated in the canister 7 to the pressurizing pump 9 is provided between the canister 7 and the pressurizing pump 9. Further, the second cylindrical container 7 b is provided with a fresh air supply pipe 13 for supplying fresh air from the outside to the canister 7. A fresh air supply valve 25 that is controlled to be opened and closed by the ECU 15 is provided at the outside air inlet of the fresh air supply pipe 13.

  A pressure sensor 27 for measuring the pressure in the fuel tank 5 is provided in the fuel tank 5. The output of the pressure sensor 27 is supplied to the ECU 15, whereby the ECU 15 detects the pressure in the fuel tank 5.

  Further, a sealing valve 29 is provided between the fuel tank 5 and the evaporated fuel supply pipe 17. The sealed valve 29 is opened and closed under the control of the ECU 15. When the sealed valve 29 is open, the evaporated fuel in the fuel tank 5 flows into the canister 7 through the evaporated fuel supply pipe 17. On the other hand, when the sealing valve 29 is closed, the fuel tank 5 is sealed, and the evaporated fuel in the fuel tank 5 does not flow toward the downstream side but remains in the fuel tank 5.

  Next, the operation of the evaporated fuel processing apparatus will be described in detail.

  In the closed tank system, the evaporated fuel in the fuel tank 5 is supplied to the canister 7 only when refueling. During refueling, for example, when the refueling port is opened, the ECU 15 opens the sealing valve 29, thereby bringing the fuel tank 5 and the canister 7 into communication. At this time, the purge valve 11 is in a closed state, and the pressurizing pump 9 is stopped. When refueling is started, the evaporated fuel is supplied to the canister 7 through the sealing valve 29 and the evaporated fuel supply pipe 17 and accumulated. When refueling is completed and the refueling port is closed, the sealing valve 29 is closed and the fuel tank 5 is sealed.

  When the amount of evaporated fuel accumulated in the canister 7 becomes equal to or greater than a predetermined value, the evaporated fuel processing apparatus purges the evaporated fuel. For example, in a predetermined engine operating state, when the accumulated amount of evaporated fuel in the canister 7 exceeds a certain value, the ECU 15 opens the purge valve 11 and the air release valve 25 and operates the pressurizing pump 9. At this time, the sealing valve 29 is closed. As a result, a negative pressure is generated on the downstream side of the pressurizing pump 9, and the outside air flows into the fresh air introduction pipe 13 through the atmosphere release valve 25. And the outside air flows from the fresh air introduction pipe 13 into the first cylindrical container 7a of the canister, flows from one end of the first cylindrical container 7a to one end of the second cylindrical container 7b, and then The accumulated fuel supply pipe 19 flows. The evaporated fuel accumulated in the canister 7 is supplied to the downstream side along the flow of the outside air, and is supplied to the engine 1 through the engine supply pipe 3. Thereby, the evaporated fuel accumulated in the canister 7 can be supplied to the engine 1.

  Next, an operation for reducing the pressure in the fuel tank 5 will be described. As described above, since the sealing valve 29 is closed except during refueling, the inside of the fuel tank 5 is sealed except during refueling. Therefore, when the fuel in the fuel tank 5 is vaporized, the pressure in the fuel tank 5 increases. Therefore, it is necessary to reduce the pressure in the fuel tank 5 at a predetermined timing, for example, before refueling, so that evaporated fuel is not released from the refueling port when the refueling port is opened.

  FIG. 2 is a flowchart showing an operation when the pressure in the fuel tank is reduced. As shown in FIG. 2, when reducing the pressure in the fuel tank 5, the ECU 15 determines in step S1 whether the pressure in the fuel tank 5 detected by the pressure sensor 27 is equal to or higher than a predetermined value. With this process, it can be determined whether the pressure in the fuel tank 5 needs to be reduced.

  Next, the ECU 15 determines whether or not a purge process is being executed in step S2. If the purge process is not being executed, the ECU 15 drives the pressure pump 9 in step S3. Thereafter, in step S4, the ECU 15 performs valve control, and opens the purge valve 11 and the atmosphere release valve 25 while maintaining the closed valve 29 in the closed state. Thereby, as shown by the arrow A in FIG. 1, an air flow is generated from the atmosphere release valve 25 toward the engine intake pipe 3. In addition, you may perform the process of step S3 and the process of step S4, changing order.

  Next, the ECU 15 opens the sealing valve 29 in step S5. When the sealing valve 29 is opened, the evaporated fuel in the fuel tank 5 is supplied with evaporated fuel by the negative pressure generated by the pressurizing pump 9 and the negative pressure generated by the air flow from the atmosphere release valve 25 to the engine supply pipe 3. It flows toward the second cylindrical container 7b of the canister 7 through the pipe 17. Since the air flow from the first cylindrical container 7a toward the accumulated fuel supply pipe 19 is generated in the second cylindrical container 7b, when the evaporated fuel enters the second cylindrical container 7b, the evaporated fuel is As indicated by the arrow B in FIG. 1, it does not flow to the atmosphere release valve 25 side from the inlet from the evaporated fuel supply pipe 17 to the second cylindrical container 7b, and passes only through the space where no adsorbent exists and immediately It is discharged from the second cylindrical container 7 b toward the accumulated fuel supply pipe 19. The evaporated fuel is supplied to the engine intake pipe 3 through the purge valve 11. Then, for example, after a predetermined time has elapsed since the start of step S5, or after the internal pressure of the fuel tank 5 has sufficiently decreased, the ECU 15 stops the pressurizing pump 9 in step S6, and the purge valve 11 and the sealing valve 29. Is closed, and the series of processes is completed.

  When the operation for reducing the pressure in the fuel tank 5 is performed, the evaporated fuel is supplied toward the engine 1. Therefore, this operation needs to be performed when the engine 1 is driven. The operation of reducing the pressure in the fuel tank 5 is detected, for example, when the pressure in the fuel tank 5 detected by the pressure sensor 27 becomes a predetermined value or more, when starting the engine 1, or by the pressure sensor 27. This can be done when the engine 1 is started immediately after the indicated pressure has reached a predetermined value or more.

  As described above, according to the fuel vapor supply apparatus according to the embodiment of the present invention, when the pressure in the fuel tank 5 detected by the pressure sensor 27 exceeds a predetermined value, the purge valve 11 and the atmospheric valve 25 are set. It is possible to open the valve and operate the pressure pump 9. Thereby, a negative pressure is generated on the downstream side of the pressurizing pump 9, and an airflow is generated from the air inlet of the canister 7 through the canister 7 toward the pressurizing pump 9. Then, after the air flow is generated, the hermetic valve 29 is opened to generate an air flow from the fuel tank 5 to the pressurizing pump 9 through the canister 7. The evaporated fuel in the fuel tank 5 is sucked from the fuel tank 5 and flows toward the canister 7. When the evaporated fuel enters the canister 7, the evaporated fuel flows from the canister 7 toward the pressurizing pump 9 due to the airflow flowing from the air introduction port toward the pressurizing pump 9. At this time, the evaporated fuel entering the canister 7 is immediately discharged from the canister 7 without contacting the adsorbent of the canister 7. Therefore, when the pressure in the fuel tank 5 is reduced, the evaporated fuel does not come into contact with the adsorbent in the canister 5. Thereby, when the pressure in the fuel tank 5 is reduced, the canister 7 can be prevented from being deteriorated. In addition, when the pressure in the fuel tank 5 is reduced, the amount of evaporated fuel accumulated in the canister 7 can be prevented from increasing by preventing the evaporated fuel from contacting the adsorbent.

  In the above-described embodiment, in the operation of lowering the pressure in the fuel tank 5, after the air flow from the atmosphere release valve 25 toward the engine intake pipe 3 is generated, the ECU 15 opens the sealing valve 29. It was. However, as a timing for opening the sealing valve 29, for example, a flow rate sensor is provided in the accumulated fuel supply pipe 19 on the upstream side of the pressurizing pump 9, and a sufficient flow velocity is obtained in the accumulated fuel supply pipe 19 by the flow rate sensor. After detecting this, the sealing valve 29 may be opened. Thereby, it is possible to prevent the evaporated fuel from contacting the adsorbent of the canister 7 more reliably.

5 Fuel tank 7 Canister 9 Pressure pump 11 Purge valve 15 ECU
25 Air release valve 27 Pressure sensor 29 Sealed valve

Claims (5)

A purge passage extending from the fuel tank toward the engine intake pipe;
A tank internal pressure sensor for detecting the pressure in the fuel tank;
A sealing valve provided between the fuel tank and the purge passage;
A canister for receiving evaporated fuel from a fuel tank and adsorbing evaporated fuel, provided on the downstream side of the sealed valve on the purge passage, and an atmospheric release valve for introducing air into the canister A canister comprising:
A pressurizing pump connected to the downstream side of the canister on the purge passage;
An evaporative fuel processing apparatus comprising: a purge valve provided on a downstream side of the pressurizing pump on the purge passage;
When the pressure detected by the tank internal pressure sensor becomes equal to or higher than a predetermined value, the purge valve and the atmosphere release valve are opened during engine operation and the pressurizing pump is operated, and then the sealing valve Evaporative fuel processing device, characterized by opening.   A flow sensor is provided between the air inlet and the pressurizing pump to measure the air flow rate in the purge passage after the pressurization pump is started, and the value measured by the flow sensor is a predetermined value or more. The evaporative fuel processing device according to claim 1, wherein the sealed valve is opened when it becomes.   3. The evaporated fuel processing according to claim 1, wherein the purge valve and the atmosphere release valve are opened, and the pressurizing pump is operated, and then the sealing valve is opened when the engine is started. apparatus.   The control for opening the purge valve and the atmosphere release valve and operating the pressurizing pump and then opening the sealing valve is performed when purge control of the canister is not performed. The evaporative fuel processing apparatus according to 2. An evaporative fuel supply unit that connects the canister and the fuel tank on the purge passage;
An accumulated fuel supply unit that connects the canister and the purge valve on the purge passage;
A fresh air supply unit that connects the canister and the atmosphere release valve;
The canister is filled with an adsorbent that adsorbs evaporated fuel at one end to which the fresh air supply unit is connected, and at the other end to which the evaporated fuel supply unit and the stored fuel supply unit are connected. A space where the adsorbent is not present is formed,
The evaporated fuel received from the fuel tank flows through the space where the adsorbent is not present to the accumulated fuel supply unit.
The evaporative fuel processing apparatus of any one of Claims 1 thru | or 4.

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