Fuel vapor handling apparatus and diagnostic apparatus thereof

• US 6,695,895 B2
• Filed: 04/12/2002
• Issued: 02/24/2004
• Est. Priority Date: 05/02/2001
• Status: Expired due to Fees

• Current Assignee: Nippon Soken, Inc., Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Nippon Soken, Inc., Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Itakura, Hideaki, Yoshioka, Mamoru, Kawano, Takanobu, Takeyama, Masaki, Kato, Naoya, Hyodo, Yoshihiko
• Primary Examiner(s): LAWRENCE JR, FRANK M
• Application Number:
  US10/120,558
• Publication Number:
  US 20020162457A1
• Time in Patent Office: 683 Days
• Field of Search: 961/09, 961/11, 961/12, 961/13, 961/14, 961/15, 961/16, 961/46, 961/47, 553/853, 123/518, 123/519, 123/520, 123/521
• US Class Current: 96/111
• CPC Class Codes: B01D 53/0454 Controlling adsorption controlling temperature swing adsorption B01D53/0462, controlling pressure swing adsorption B01D53/047
• CPC Class Codes: F02M 2025/0881 with means to heat or cool the canister
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 25/0818 having means for pressurising the evaporative emission space
• CPC Class Codes: F02M 25/0872 Details of the fuel vapour pipes or conduits
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation

Abstract

A fuel vapor handling apparatus supplies a purging air to a canister by using a purge pump and purges fuel desorbed from the canister into an intake pipe. A controller intermittently operates the purge so that the canister internal temperature recovers from a reduced level caused by the latent heat of vaporization of fuel during an operating period of the purge pump. Therefore, desorption of fuel from the canister during an operating period is facilitated. Since the actual operating time of the purge pump is reduced, the life of a motor that is a power unit of the purge pump becomes longer.

Claims

1. A fuel vapor handling apparatus comprising:

a canister that includes a container that contains an adsorbent that adsorbs a fuel vapor from a fuel tank, the container having an atmospheric port that is open to an atmospheric pressure, a fuel vapor introducing port for connection to the fuel tank, and a purge port for connection to an intake pipe of an internal combustion engine;

a purge pump coupled to the canister to supply air into the canister via the atmospheric port so as to purge a fuel desorbed from the adsorbent into the intake pipe via the purge port; and

a controller that controls the purge pump to intermittently operate during a purge operation.

2. The fuel vapor handling apparatus according to claim 1, further comprising a heater coupled to the canister to heat an interior of the canister.

3. The fuel vapor handling apparatus according to claim 1, wherein the controller controls a purge valve that changes between a first state to connect the canister and the intake pipe and a second state to disconnect the canister and the intake pipe, and wherein the controller causes the purge pump and the purge valve to intermittently operate with a timing such that opening of the purge valve is delayed by a predetermined time from a timing at which the purge pump turns on.

4. The fuel vapor handling apparatus according to claim 1, wherein the controller controls a purge valve that changes between a first state to connect the canister and the intake pipe and a second state to disconnect the canister and the intake pipe, and wherein the controller causes the purge pump and the purge valve to intermittently operate with a timing such that the purge valve closes and the purge pump turns off substantially synchronously.

5. The fuel vapor handling apparatus according to claim 3, wherein the controller causes the purge valve to close and the purge pump to turn substantially synchronously.

6. The fuel vapor handling apparatus according to claim 1, wherein the controller determines a number of on/off repetitions of the purge pump so that a cumulative amount of actual operating duration of the purge pump during an intermittent operation increases as an instructed purge amount increases.

7. The fuel vapor handling apparatus according to claim 1, further comprising a fuel vapor concentration sensor that is provided within a passage extending from the purge port to the intake pipe and that detects a concentration of the fuel vapor in the passage,

wherein the controller stops operating the purge pump if the concentration of the fuel vapor reaches a pre-set purge completing concentration.

8. The fuel vapor handling apparatus according to claim 1, further comprising:

a fuel vapor concentration sensor that is provided within a passage extending from the purge port to the intake pipe and that detects a concentration of the fuel vapor in the passage; and

wherein the controller adjusts an amount of flow of a purge fuel toward the intake pipe, and computes an amount of purged fuel based on the amount of flow of the purge fuel and a result of detection by the fuel vapor concentration sensor, to determine the amount of flow of the purge fuel so that the amount of purged fuel becomes within a pre-set range.

9. The fuel vapor handling apparatus according to claim 8, further comprising a heater that heats an interior of the canister,

wherein the controller controls the heater and the purge pump, so as to start operating the heater if the amount of purged fuel is not brought into the pre-set range by an operation of the purge pump while the heater is in a non-operation state.

10. The fuel vapor handling apparatus according to claim 8, further comprising a remaining fuel sensor that detects an amount of fuel remaining in the fuel tank,

wherein the controller stops operating the heater if the detected amount of fuel remaining becomes less than a pre-set lower limit amount.

11. The fuel vapor handling apparatus according to claim 10, wherein the controller stops operating the heater if the concentration of the fuel vapor becomes lower than a pre-set lower limit concentration.

12. The fuel vapor handling apparatus according to claim 8, further comprising a tank internal pressure sensor that detects an internal pressure of the fuel tank,

wherein the controller stops operating the heater if the internal pressure of the fuel tank becomes lower than a pre-set lower limit pressure.

18. A diagnostic apparatus for detecting an operation abnormality of the fuel vapor handling apparatus of claim 1, comprising:

a purge valve between the canister and the intake pipe;

a pressure sensor in communication with a closed space defined by the canister and a fuel tank; and

wherein the controller performs a diagnostic operation by;

controlling the purge valve to close and thereby disconnect communication between the canister and the intake pipe;

using the pressure sensor to detect a pressure in the closed space formed upon the disconnection from the intake pipe caused by the purge valve, the closed space including the canister and the fuel tank;

pressurizing the closed space by operating the purge pump while the purge valve is closed; and

determining an operation state of the purge pump based on an increasing rate of the pressure detected by the pressure sensor.

19. The diagnostic apparatus according to claim 18, wherein the controller compares the pressure detected by the pressure sensor with a target pressure, and compares a time of operation of the purge pump during a closed state of the purge valve with a pre-set upper limit time, and wherein the controller determines that the purge pump has an operation abnormality if the time of operation of the purge pump becomes longer than the upper limit time while the detected pressure is below the target pressure.

13. A fuel vapor handling apparatus comprising:

a canister that includes a container that contains an adsorbent that adsorbs a fuel vapor from a fuel tank, the container having an atmospheric port that is open to an atmospheric pressure, a fuel vapor introducing port for connection to the fuel tank, and a purge port for connection to an intake pipe of an internal combustion engine;

a purge pump coupled to the canister to supply air into the canister via the atmospheric port so as to purge a fuel desorbed from the adsorbent into the intake pipe via the purge port;

a metering valve that is adapted to variably change a degree of opening of the atmospheric port; and

a controller that controls the metering valve to adjust the degree of opening of atmospheric port.

14. A fuel vapor handling apparatus comprising:

a canister that includes a container that contains an adsorbent that adsorbs a fuel vapor from a fuel tank, the container having an atmospheric port that is open to an atmospheric pressure, a fuel vapor introducing port for connection to the fuel tank, and a purge port for connection to an intake pipe of an internal combustion engine;

a purge pump coupled to the canister to supply air into the canister via the atmospheric port so as to purge a fuel desorbed from the adsorbent into the intake pipe via the purge port;

a heater that heats an interior of the canister; and

a controller that controls the purge pump and the heater, to operate the heater before starting operating the purge pump.

15. A fuel vapor handling apparatus comprising:

a canister that includes a container that contains an adsorbent that adsorbs a fuel vapor from a fuel tank, the container having an atmospheric port that is open to an atmospheric pressure, a fuel vapor introducing port for connection to the fuel tank, and a purge port for connection to an intake pipe of an internal combustion engine;

a purge pump coupled to the canister to supply air into the canister via the atmospheric port so as to purge a fuel desorbed from the adsorbent into the intake pipe via the purge port;

a refueling detecting sensor that detects whether the fuel tank has been refueled; and

a controller that controls the purge pump, so that the purge pump operates when refueling is performed.

16. A fuel vapor handling apparatus comprising:

a canister that includes a container that contains an adsorbent that adsorbs a fuel vapor from a fuel tank, the container having an atmospheric port that is open to an atmospheric pressure, a fuel vapor introducing port for connection to the fuel tank, and a purge port for connection to an intake pipe of an internal combustion engine;

a purge pump coupled to the canister to supply air into the canister via the atmospheric port so as to purge a fuel desorbed from the adsorbent into the intake pipe via the purge port;

a fuel vapor concentration sensor that is provided within a passage extending from the purge port to the intake pipe, and that detects a concentration of the fuel vapor in the passage; and

a controller that controls the purge pump, so that the purge pump operates if the concentration of the fuel vapor exceeds a pre-set purge staffing concentration.

17. A fuel vapor handling apparatus comprising:

a canister that includes a container that contains an adsorbent that adsorbs a fuel vapor from a fuel tank, the container having an atmospheric port that is open to an atmospheric pressure, a fuel vapor introducing port for connection to the fuel tank, and a purge port for connection to an intake pipe of an internal combustion engine;

a purge pump coupled to the canister to supply air into the canister via the atmospheric port so as to purge a fuel desorbed from the adsorbent into the intake pipe via the purge port;

a fuel vapor concentration sensor that is provided within a passage extending from the purge port to the intake pipe and that detects a concentration of the fuel vapor in the passage; and

a controller that controls the purge pump, wherein the controller computes an amount of purged fuel based on an amount of flow of a purge and a result of detection by the fuel vapor concentration sensor, and is set so that the purge pump operates if the concentration of the fuel vapor exceeds a pre-set purge starting concentration.

20. A canister purge system comprising:

a canister that adsorbs a fuel vapor from a fuel tank of an internal combustion engine;

a vapor passage that connects a space formed above a fuel liquid surface in the fuel tank to the canister;

a purge passage that connects the canister and an engine intake passage;

an atmospheric port that places the canister and an atmosphere in communication with each other;

a purge pump coupled to the canister to supply a gas from the intake passage to the canister via the purge passage, the purge pump being operable independently of an operation of the engine; and

a purge pump controller that supplies the fuel vapor remaining in the engine intake passage into the canister by operating the purge pump after the engine stops.

21. The canister purge system according to claim 20, wherein:

the purge pump is a reversible pump, and the purge pump controller operates the purge pump in a forward direction so as to supply the fuel vapor from the canister to the engine intake passage via the purge passage during an operation of the engine, and the purge pump controller operates the purge pump in the reverse direction to supply the fuel vapor remaining in the engine intake passage into the canister after the engine stops.

22. The canister purge system according to claim 20, wherein the purge pump is disposed in the purge passage.

23. The canister purge system according to claim 20, wherein the purge pump is connected to the atmospheric port of the canister.

24. The canister purge system according to claim 20, wherein the purge pump controller suspends an operation of the purge pump if an engine temperature after the engine stops is not greater than a predetermined temperature.

25. The canister purge system according to claim 20, wherein the purge pump controller continues operating the purge pump in the reverse direction for a predetermined time after the engine stops, and then stops operating the purge pump, and wherein the purge pump controller deduces the predetermined time as an engine temperature after the engine stops increases.

26. The canister purge system according to claim 20, wherein the purge pump controller starts operating the purge pump after a predetermined delay time elapses following a stoppage of the engine, and the purge pump controller sets the predetermined delay time based on an engine temperature occurring when the engine stops.

27. The canister purge system according to claim 20, wherein if after a stoppage of the engine, the engine temperature rises above an engine temperature occurring at the stoppage of the engine, the purge pump controller operates the purge pump in accordance with the engine temperature rise.

28. The canister purge system according to claim 21, further comprising a diagnostic apparatus which, after a stoppage of the engine, causes the purge pump to operate in the reverse direction by using the purge pump controller, and thereby adjusts an internal pressure of a purge system that includes the purge passage, the canister and the fuel tank, to a value that provides a pressure difference relative to an atmospheric pressure, and which, after the internal pressure is adjusted, closes the purge system, and determines whether the purge system has a leak based on a change that occurs in the internal pressure of the purge system after the purge system is closed.