Leak check apparatus for fuel vapor purge system

• US 20020139173A1
• Filed: 04/03/2002
• Published: 10/03/2002
• Est. Priority Date: 04/03/2001
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kano, Masao, Koyama, Nobuhiko
• Granted Patent: US 6,604,407 B2
• Time in Patent Office: Days
• US Class Current: 73/49.7
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation

Abstract

A fuel vapor purge system has a canister and a pump on a purge line arranged between the canister to the intake passage. The system further has a sub-canister on a branch passage of the purge line. The pump is driven when the engine is stopped, and reduces an inside pressure of the system. The vapor discharged from the pump is adsorbed in the sub-canister, therefore, no vapor is emitted to the atmosphere. The controller checks a leak by monitoring the inside pressure after the inside pressure is reduced. It is possible to improve an accuracy of the leak detection since a leak check is executed when the engine is stopped.

Claims

1. A leak check apparatus for a fuel vapor purge system having a fuel tank, a main canister for adsorbing fuel vapor in the fuel tank and a purge passage for purging the adsorbed vapor to an intake passage of an engine, the apparatus comprising:

at least one valve which defines a closed space including the fuel tank, the main canister and at least a part of the purge passage;

a pump which discharges gaseous component in the closed space for reducing an inside pressure of the closed space;

a sub canister disposed in series to the pump which adsorb the vapor in the gaseous component discharged by the pump; and

a sensor which outputs a signal indicative of a leak on the closed space.

2. The leak check apparatus according to claim 1, further comprising a controller that includes:

means for controlling the valve to provides the closed space;

means for controlling the pump to reduce the inside pressure to a predetermined pressure; and

means for detecting the leak based on the signal detected by the sensor.

3. The leak check apparatus according to claim 2, wherein the main canister has a first end and a second end separated by an adsorbent, and wherein the sub canister has a first end and a second end separated by an adsorbent, and wherein

the purge passage includes:

a gas line that communicates the first end of the main canister and the fuel tank;

a purge line that communicates the first end of the main canister and the intake passage of the engine;

an intake line that communicates the second end of the main canister and the atmosphere;

a sub purge line that communicates the first end of the sub canister and the intake passage of the engine;

a leak check line that communicates the second end of the sub canister and the purge line; and

a sub intake line that communicates the second end of the sub canister and the atmosphere, and wherein

the valve includes;

a canister valve disposed on the intake line;

a purge valve disposed on the purge line;

a sub purge valve disposed on the sub purge line;

a sub canister valve disposed on the sub intake line; and

a leak check valve disposed on the leak check line, and

wherein the pump and the purge valve are disposed in the purge line in series and wherein the leak check line is connected to between the pump and the purge valve, and wherein

the means for controlling the valve includes;

first means for controlling the valves before reducing the inside pressure, so as to close the purge valve, open the sub purge valve, open the leak check valve, close the sub canister valve and close the canister valve; and

second means for controlling the valves after reducing the inside pressure, so as to close the purge valve, close the sub purge valve, open the leak check valve, close the sub canister valve and close the canister valve, and wherein

the means for detecting the leak detects the leak after the second means closes the sub purge valve.

4. The leak check apparatus according to claim 3, wherein the controller further comprises:

means for purging the sub canister when the engine is running, by closing the purge valve, opening the sub purge valve, closing the leak check valve, and opening the sub canister valve; and

means for purging the main canister when the engine is running, by opening the purge valve, closing the sub purge valve, and opening the canister valve.

5. The leak check apparatus according to claim 3, wherein the sensor is a pressure sensor disposed on the closed space to detect the inside pressure, and wherein the means for detecting the leak detects the leak based on a characteristic of a pressure variation detected by the pressure sensor such as a pressure variation in a predetermined time or duration until the inside pressure reaches to a predetermined pressure.

6. The leak check apparatus according to claim 1, wherein the pump discharges the gaseous component in the closed space when the engine is stopped.

7. A leak check apparatus for a fuel vapor purge system having a fuel tank, a canister for adsorbing fuel vapor in the fuel tank and a purge passage for purging the adsorbed vapor to an intake passage of an engine, the apparatus comprising:

at least one valve which defines a closed space including the fuel tank, the main canister and at least a part of the purge passage, and connects at least the remaining part of the purge passage to the intake passage of the engine;

a pump which pressurizes the closed space when the engine is stopped;

a first sensor which outputs a signal indicative of a leak on the closed space; and

a second sensor disposed on the engine which outputs a signal indicative of a leak on the remaining part of the purge passage when the engine is running.

8. The leak check apparatus according to claim 7, further comprising a controller that includes:

first valve controlling means for controlling the valve to define the closed space when the engine is stopped;

pump controlling means for controlling the pump to pressurize the inside pressure to a predetermined pressure when the engine is stopped; and

first detecting means for detecting the leak on the closed space based on the signal detected by the first sensor when the engine is stopped;

second valve controlling means for controlling the valve to connect at least the remaining part or the purge passage to the intake passage of the engine when the engine is running; and

second detecting means for detecting the leak on the remaining part of the purge passage when the engine is running.

9. The leak check apparatus according to claim 8, wherein the canister has a first end and a second end separated by an adsorbent, and wherein the purge passage includes:

an gas line that communicates the first end of the canister and the fuel tank;

a purge line in which the pump is disposed that communicates the first end of the canister and the intake passage of the engine;

an intake line that communicates the second end of the canister and the atmosphere;

a suction line that communicates the intake passage of the engine and the purge line on a suction side of the pump; and

a pressurizing line that communicates the second end of the canister and the purge line on a discharge side of the pump, and wherein

the valve includes;

a canister valve disposed on the intake line;

a purge valve disposed on the purge line on the discharge side of the pump;

a first three port valve disposed on a connecting point between the purge line and the suction line; and

a second three port valve disposed on a connecting point between the purge line and the pressuring line, and wherein

the first valve controlling means for controlling the valve includes;

preparation means for controlling the valves before pressurizing the inside pressure, so as to close the canister valve, connect the suction line and the suction side of the pump by the first three port valve, and connect the pressuring line and the discharge side of the pump by the second three port valve; and

holding means for controlling the valves after pressurizing the inside pressure, so as to close the canister valve, disconnect the suction line from the purge line by the first three port valve, and connect the pressuring line and the discharge side of the pump by the second three port valve, and wherein

the second valve controlling means for controlling the valve controls the valves so as to open the purge valve, connect the suction line and the suction side of the pump by the first three port valve, and disconnect the pressuring line from the purge line by the second three port valve.

10. The leak check apparatus according to claim 9, wherein the controller further comprises:

means for purging the canister when the engine is running, by opening the purge valve, opening the canister valve, driving the first and second three port valves so as to communicate the purge line to the intake passage of the engine.

11. The leak check apparatus according to claim 9, wherein the sensor is a pressure sensor disposed on the closed space to detect the inside pressure, and wherein the first detecting means for detecting the leak on the closed space detects the leak based on a characteristic of a pressure variation detected by the pressure sensor such as a pressure variation in a predetermined time or duration until the inside pressure reaches to a predetermined pressure.

12. The leak check apparatus according to claim 8, wherein the second sensor is an oxygen sensor disposed in an exhaust passage of the engine and detects an oxygen amount in exhaust gas, and wherein the second detecting means for detecting the leak on the remaining part of the purge passage detects the leak when the second sensor detects an excessive oxygen amount.

13. The leak check apparatus according to claim 7, further comprising means for controlling the valve to release the inside pressure in the closed space through the canister after a leak check procedure is completed.