FUEL VAPOR PROCESSING SYSTEMS

• US 20120145133A1
• Filed: 12/13/2011
• Published: 06/14/2012
• Est. Priority Date: 12/14/2010
• Status: Active Grant

• Current Assignee: Aisan Kogyo Kabushiki Kaisha, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Aisan Kogyo Kabushiki Kaisha, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: TAKAMATSU, Hiroshi
• Granted Patent: US 9,181,906 B2
• Time in Patent Office: Days
• US Class Current: 123/520
• CPC Class Codes: F02D 2200/0602 Fuel pressure
• CPC Class Codes: F02D 41/0032 Controlling the purging of the canister as a function of the engine operating conditions
• CPC Class Codes: F02D 41/0045 Estimating, calculating or determining the purging rate, amount, flow or concentration
• CPC Class Codes: F02M 25/0836 Arrangement of valves controlling the admission of fuel vapour to an engine, e.g. valve being disposed between fuel tank or absorption canister and intake manifold
• CPC Class Codes: F02M 25/089 Layout of the fuel vapour installation

Abstract

A fuel vapor processing system includes a canister, a tank passage communicating between the canister and the fuel tank, and a purge passage communicating between the canister and the intake air passage. Fuel vapor adsorbed by the canister can be desorbed and purged into the intake air passage via the purge passage due to a negative pressure produced in the intake air passage. A desorption promoting device can promote desorption of fuel vapor from the canister. A control unit controls the desorption device, so that the desorption promoting device promotes desorption of fuel vapor from the canister during desorption through the purge passage due to the negative pressure.

Claims

1. A fuel vapor processing system for processing fuel vapor produced in a fuel tank storing fuel that is supplied to an internal combustion engine having an intake air passage, comprising:

a canister capable of adsorbing fuel vapor;

a tank passage communicating between the canister and the fuel tank;

a purge passage communicating between the canister and the intake air passage of the internal combustion engine;

an atmospheric passage communicating between the canister and the atmosphere;

a purge control valve provided in the purge passage;

a control unit configured to control the purge control valve;

wherein fuel vapor produced within the fuel tank is introduced into the canister via the tank passage, so that the fuel vapor is adsorbed by the canister;

wherein when the purge control valve is opened by the control unit during running of the internal combustion engine, air is drawn into the canister via the atmospheric passage due to a negative pressure produced within the intake air passage of the internal combustion engine, so that fuel vapor is desorbed from the canister by the flow of the drawn air and is purged into the intake air passage via the purge passage;

an electromagnetic valve provided in the tank passage and capable of opening and closing the tank passage; and

a desorption promoting device capable of promoting desorption of fuel vapor from the canister;

wherein the control unit is configured to further control the electromagnetic valve and the desorption promoting device such that, during opening of the purge control valve, the desorption promoting device operates to promote desorption of fuel vapor from the canister before the electromagnetic valve is opened.

2. The fuel vapor processing system as in claim 1, further comprising a tank internal pressure detector configured to detect a tank internal pressure within the fuel tank, wherein the control unit is configured such that the desorption promoting device is operated when the tank internal pressure is equal to or higher than a predetermined value.

3. The fuel vapor processing system as in claim 2, further comprising a purge concentration detector configured to detect concentration of fuel vapor contained in a purge gas that is purged from the canister into the intake air passage via the purge passage,

wherein the control unit is further configured such that the desorption promoting device is operated in the case that the fuel vapor concentration detected by the concentration detector is equal to or higher than a predetermined value and that the tank internal pressure detected by the tank internal pressure detector is equal to or higher than a predetermined value.

4. The fuel vapor processing system as in claim 1, wherein the control unit is further configured such that the electromagnetic valve is closed after the desorption promoting device is operated to promote desorption of fuel vapor from the canister.

5. The fuel vapor processing system as in claim 1, wherein the desorption promoting device comprises a decompression device capable of reducing the pressure within the canister.

6. The fuel vapor processing system as in claim 5, wherein the decompression device comprises an electromagnetic valve provided in the atmospheric passage and capable of switching flow rate of air flowing through the atmospheric passage from a first flow rate to a second flow rate smaller than the first flow rate.

7. The fuel vapor processing system as in claim 1, wherein the desorption promoting device comprises a heating device configured to heat inside of the canister.

8. A fuel vapor processing system for processing fuel vapor produced in a fuel tank storing fuel that is supplied to an internal combustion engine having an intake air passage, comprising:

a canister capable of adsorbing fuel vapor;

a tank passage communicating between the canister and the fuel tank;

a purge passage communicating between the canister and the intake air passage of the internal combustion engine;

an atmospheric passage communicating between the canister and the atmosphere;

a purge control valve provided in the purge passage;

a control unit configured to control the purge control valve;

wherein fuel vapor produced within the fuel tank is introduced into the canister via the tank passage, so that the fuel vapor is adsorbed by the canister;

wherein when the purge control valve is opened under the control of the control unit during running of the internal combustion engine, air is drawn into the canister via the atmospheric passage due to a negative pressure produced in the air intake passage of the internal combustion engine, so that fuel vapor is desorbed from the canister by the flow of the drawn air and is purged into the intake air passage via the purge passage;

a first electromagnetic valve provided in the tank passage and configured to open and close the tank passage; and

a second electromagnetic valve provided in the atmospheric passage and configured to switch flow rate of air flowing through the atmospheric passage between a first flow rate and a second flow rate smaller than the first flow rate; and

wherein the control unit is configured to further control the first and second electromagnetic valves such that the first electromagnetic valve is operated during the time when the purge control valve is opened and the second electromagnetic valve is switched to the side of the second flow rate.

9. The fuel vapor processing system as in claim 8, wherein the control unit is configured to further control the first and second electromagnetic valves such that:

the second electromagnetic valve is switched to the side of the first flow rate and the first electromagnetic valve is opened during refueling to the fuel tank; and

the second electromagnetic valve is switched to the side of the second flow rate during non-refueling to the fuel tank.

10. A fuel vapor processing system for processing fuel vapor produced in a fuel tank storing fuel to be supplied to an internal combustion engine having an intake air passage, comprising:

a canister capable of adsorbing fuel vapor;

a tank passage communicating between the canister and the fuel tank, so that fuel vapor produced in the fuel tank can flow into the canister via the tank passage;

a purge passage communicating between the canister and the intake air passage, so that fuel vapor adsorbed by the canister can be desorbed from the canister and purged into the intake air passage due to a negative pressure produced in the intake air passage;

a desorption promoting device configured to promote desorption of fuel vapor from the canister; and

a control unit configured to control the desorption device, so that the desorption promoting device promotes desorption of fuel vapor from the canister during desorption through the purge passage due to the negative pressure.

11. The fuel vapor processing system as in claim 10, wherein the desorption promoting device comprises a heating device configured to heat inside of the canister.

12. The fuel vapor processing system as in claim 10, further comprising an atmospheric passage communicating between the canister and the atmosphere, so that air can flow into the canister via the atmospheric passage, wherein the desorption promoting device comprises a valve disposed in the atmospheric passage and configured to regulate flow of air flowing through the atmospheric passage under the control of the control unit.

13. The vapor processing system as in claim 10, further comprising:

a first valve provided in the tank passage and configured to open and close the tank passage under the control of the control unit;

a second valve provided in the purge passage and configured to open and close the purge passage under the control of the control unit;

wherein the control unit controls the desorption promoting device, the first valve and the second valve such that during the period when the second valve opens the purge passage, the desorption promoting device promotes desorption of fuel vapor before the first valve opens the tank passage.