Failure diagnostic system for fuel vapor processing apparatus

• US 20050022588A1
• Filed: 07/26/2004
• Published: 02/03/2005
• Est. Priority Date: 07/31/2003
• Status: Active Grant

• Current Assignee: Aisan Kogyo Kabushiki Kaisha
• Original Assignee: Aisan Kogyo Kabushiki Kaisha
• Inventors: Hayakawa, Masamitsu, Hayakawa, Masaharu
• Granted Patent: US 7,036,359 B2
• Time in Patent Office: Days
• US Class Current: 73/114.410
• CPC Class Codes: B60K 2015/03514 with vapor recovery means
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system

Abstract

In a failure diagnostic system for a fuel vapor processing apparatus, a processing flow path comprising a vapor line, a canister and a purge line is closed with a vapor control valve and a purge control valve. The interior of the processing flow path is reduced in pressure or pressurized by rotating an air pump of a pump module in a forward or reverse direction. An electronic control unit (ECU) closes the vapor control valve and the purge control valve to close the processing flow path after stop of the engine and, when the fuel temperature detected by a temperature sensor is lower than a predetermined value, reduces the internal pressure of the processing flow path through an air pump, then checks air-tightness of the interior of the processing flow path based on behavior of a vapor pressure detected by a pressure sensor. The ECU closes the processing flow path and, when the fuel temperature detected is not lower than the predetermined value, pressurizes the interior of the processing flow path through the air pump, then checks air-tightness of the processing flow path based on behavior of a vapor pressure subsequently detected.

Claims

1. A failure diagnostic system for a fuel vapor processing apparatus which is disposed correspondingly to an engine mounted on a vehicle and wherein fuel vapor generated in a fuel tank is trapped by a canister and the trapped fuel vapor is purged to an intake passage in the engine,

wherein the fuel vapor processing apparatus comprises a processing flow path extending from the fuel tank to the intake passage and including the canister;

and

the failure diagnostic system comprises;

closure means for closing the processing flow path;

pressurizing means for pressurizing the interior of the processing flow path;

pressure reducing means for reducing the internal pressure of the processing flow path;

pressure detecting means for detecting an internal pressure of the processing flow path;

temperature detecting means for detecting an atmosphere temperature of the fuel tank;

first diagnostic means which, after stop of the engine, controls the closure means to close the processing flow path and which, when the atmosphere temperature detected by the temperature detecting means is lower than a predetermined value, controls the pressure reducing means to reduce the internal pressure of the processing flow path and checks air-tightness of the processing flow path based on behavior of the pressure detected by the pressure detecting means after the pressure reduction; and

second diagnostic means which, after stop of the engine, controls the closure means to close the processing flow path and which, when the atmosphere temperature detected by the temperature detecting means is higher than a predetermined value, controls the pressurizing means to pressurize the interior of the processing flow path and checks the air-tightness of the processing flow path based on behavior of the pressure detected by the pressure detecting means after the pressurization.

2. The failure diagnostic system according to claim 1, wherein

the pressurizing means and the pressure reducing means are constituted by a single air pump,

the first diagnostic means reduces the internal pressure of the processing flow path by rotating the air pump forward to suck in air, and

the second diagnostic means pressurizes the interior of the processing flow path by rotating air pump reversely to discharge air.

3. The failure diagnostic system according to claim 1, further comprising:

warning means for informing occurrence of an air-tightness failure when the first or the second diagnostic means determines that the processing flow path involves the failure in air-tightness; and

a memory for storing the presence of the failure.

4. The failure diagnostic system according to claim 1, wherein

the fuel vapor processing apparatus further comprises a purge assisting control means which, when the fuel vapor trapped by the canister is purged to the intake passage, controls the pressurizing means to pressurize the interior of the canister and thereby assist the purging.

5. The failure diagnostic system according to claim 2, wherein the fuel vapor processing apparatus further comprises a purge assisting control means which, when the fuel vapor trapped by the canister is purged to the intake passage, controls the air pump to pressurize the interior of the canister and thereby assist the purging.

6. A failure diagnostic system for a fuel vapor processing apparatus which is disposed correspondingly to an engine mounted on a vehicle and wherein fuel vapor generated in a fuel tank is trapped by a canister through a vapor line and the trapped fuel vapor is purged to an intake passage in the engine through a purge line,

wherein the fuel vapor processing apparatus comprises a processing flow path extending from the fuel tank to the intake passage and including the vapor line, the canister and the purge line;

the failure diagnostic system comprises;

a vapor control valve disposed in the vapor line for closing the processing flow path and a purge control valve disposed in the purge line;

a single air pump for selectively pressurizing the interior of the processing flow path or reducing the internal pressure of the processing flow path;

a pressure sensor for detecting an internal pressure of the processing flow path;

a temperature sensor for detecting an atmosphere temperature of the fuel tank; and

an electronic control unit for checking air-tightness of the processing flow path; and

the electronic control unit, after stop of the engine, controls the vapor control valve and the purge control valve to close the processing flow path and, when the atmosphere temperature detected by the temperature sensor is lower than a predetermined value, causes the air pump to rotate forward to suck in air, thereby reducing the internal pressure of the processing flow path, and checks air-tightness of the processing flow path based on behavior of the pressure detected by the pressure sensor after the pressure reduction, and

the electronic control unit, after stop of the engine, controls the vapor control valve and the purge control valve to close the processing flow path and, when the atmosphere temperature detected by the temperature sensor is not lower than the predetermined value, causes the air pump to rotate reversely to discharge air, thereby pressurizing the interior of the processing flow path, and checks air-tightness of the processing flow path based on behavior of the pressure detected by the pressure sensor after the pressurization.

7. The failure diagnostic system according to claim 6, further comprising:

warning means for informing the occurrence of an air-tightness failure when the electronic control unit determines that the processing flow path involves the failure in air-tightness; and

a memory for storing the presence of the failure.

8. The failure diagnostic system according to claim 6, wherein

the fuel vapor processing apparatus further comprises a purge assisting control means which, when the fuel vapor trapped by the canister is purged to the intake passage, controls the air pump to pressurize the interior of the canister and thereby assist the purging.

9. A canister included in a fuel vapor processing apparatus for processing fuel vapor generated in a fuel tank and incorporating, in a casing, an adsorbent for adsorbing the fuel vapor,

wherein the canister comprises a diagnosing function part for the fuel vapor processing apparatus, the diagnosing function part being integrally mounted nearly centrally of the casing.

10. The canister according to claim 9, wherein the diagnosing function part is a pump module for changing the internal pressure of the casing.

11. The canister according to claim 10, wherein

the casing is in the shape of a generally U-shaped cylindrical body having a first end portion through which the fuel vapor is introduced in and discharged out of the canister and a second end portion which is able to communicate with atmosphere, and

the casing includes a valley portion positioned nearly centrally, and the pump module is mounted in the valley portion.

12. The canister according to claim 11, wherein

an insertion hole is formed in the bottom of the valley portion, and an engaging portion to be inserted and engaged into the insertion hole is formed in a lower end of the pump module.

13. The canister according to claim 10, wherein

the pump module comprises a pump, a check valve disposed on an air inlet side of the pump, and a solenoid valve disposed on an air outlet side of the pump.

14. The canister according to claim 11, wherein

the pump module comprises a pump, a check valve disposed on an air inlet side of the pump, and a solenoid valve disposed on an air outlet side of the pump.

15. A pump module connected to a fuel vapor processing apparatus which is disposed correspondingly to an engine mounted on a vehicle and wherein fuel vapor generated in a fuel tank is trapped by a canister and a fuel component contained in the trapped fuel vapor is purged to an intake passage in the engine, the pump module being used for reducing the internal pressure of the fuel vapor processing apparatus and for diagnosing a failure of the fuel vapor processing apparatus based on behavior of the pressure detected at this time,

wherein the pump module comprises:

a vacuum pump for developing a negative pressure in the fuel vapor processing apparatus;

a connection port connected to the fuel vapor processing apparatus;

an air port including a first end and a second end, the first end being opened to the atmosphere;

an orifice passage including a first end and a second end, the first end being connected to the connection port, the second end being connected to the vacuum pump, with an orifice being provided in an intermediate position of the orifice passage to calculate a reference value in failure diagnosis;

a pressure detecting means for detecting an internal pressure of the fuel vapor processing apparatus and that of the orifice passage; and

a change-over valve for changing from a state of communication to a cut-off state or vice versa between the connection port and the air port; and

the orifice is disposed in a vertex direction in a mounted state of the pump module on the vehicle and is located at a higher position than an opening/closing portion of the change-over valve.

16. The pump module according to claim 15, further comprising a case and wherein

the change-over valve comprises an actuator and a valve body, the orifice is disposed between the actuator and the valve body in the change-over valve, and

the change-over valve can be mounted in the case while being rotated about an extension line extending in a movable direction of the valve body.

17. The pump module according to claim 15, further comprising a case, the case having a plurality of mounting holes for mounting the pump module to the vehicle, and wherein

the change-over valve comprises an actuator and a valve body,

the orifice is disposed between the actuator and the valve body in the change-over valve, and

at the time of mounting the pump module in the vehicle by utilizing the plural mounting holes, the change-over valve can be mounted in the case while being rotated about an extension line extending in a movable direction of the valve body, thereby disposing the orifice in the vertex direction and at a higher position than the opening/closing portion of the change-over valve.

18. A failure diagnostic system for a fuel vapor processing apparatus, using the pump module according to claim 15.

19. A failure diagnostic system for a fuel vapor processing apparatus, using the pump module according to claim 16.

20. A pump module connected to a fuel vapor processing apparatus which is disposed correspondingly to an engine mounted on a vehicle and wherein fuel vapor generated in a fuel tank is trapped by a canister and a fuel component contained in the trapped fuel vapor is purged to an intake passage in the engine, the pump module being used for reducing the internal pressure of the fuel vapor processing apparatus and for diagnosing a failure of the fuel vapor processing apparatus based on behavior of the pressure detected at this time,

the pump module comprising:

a case;

a vacuum pump installed in the case to develop a negative pressure in the fuel vapor processing apparatus;

a connection port formed in the case and connected to the fuel vapor processing apparatus;

an air port formed in the case and including a first end and a second end, the first end being opened to the atmosphere;

an orifice passage formed in the case and having a first end and a second end, the first end being connected to the connection port, the second end being connected to the vacuum pump, with an orifice being provided in an intermediate position of the orifice passage to calculate a reference value in diagnosis; and

a change-over valve for changing from a state of communication to a cut-off state or vice versa between the connection port and the air port,

the change-over valve being mounted in the case while being rotated about an extension line extending in a movable direction of a valve body of the change-over valve, thereby disposing the orifice in a vertex direction and at a higher position than an opening/closing portion of the change-over valve.