Leakage determination system for evaporative fuel processing system

• US 6,761,058 B2
• Filed: 06/06/2001
• Issued: 07/13/2004
• Est. Priority Date: 06/08/2000
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Yamaguchi, Takashi, Isobe, Takashi
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Garber, Charles D.
• Application Number:
  US09/874,036
• Publication Number:
  US 20010049958A1
• Time in Patent Office: 1,133 Days
• Field of Search: 73/40, 73/405.R, 73/497, 73/481, 123/520, 702/51
• US Class Current: 73/40.50R
• 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

There is provided a leakage determination system for an evaporative fuel processing system, which, even when pressure within the evaporative fuel processing system is temporarily increased e.g. due to an increase in the amount of generation of evaporative fuel in a fuel tank, is capable of performing an accurate leakage determination by eliminating the influence of the temporary rise in the pressure within the evaporative fuel processing system on the leakage determination. A pressure sensor detects pressure within the evaporative fuel processing system. Negative pressure is introduced from the intake system into the evaporative fuel processing system, whereby the pressure within the evaporative fuel processing system is reduced until the detected pressure becomes equal to a predetermined negative pressure. After the pressure reduction, the negative pressure is introduced from the intake system into the evaporative fuel processing system under predetermined conditions. Whether or not there is a leak in the evaporative fuel processing system is determined based on a state of the pressure within the evaporative fuel processing system, which has been detected during the introduction of the negative pressure from the intake system.

Claims

1. A leakage determination system for an evaporative fuel processing system that causes a canister to absorb evaporative fuel generated from a fuel tank and supplies the evaporative fuel absorbed in the canister to an intake system of an internal combustion engine,

the leakage determination system comprising:

pressure detection means for detecting pressure within the evaporative fuel processing system;

primary pressure reduction means for primarily reducing the pressure within the evaporative fuel processing system until the detected pressure becomes equal to a predetermined negative pressure, by introducing negative pressure from the intake system;

secondary pressure reduction means for secondarily reducing the pressure within the evaporative fuel processing system by introducing the negative pressure from the intake system successively after the primary pressure reduction by said primary pressure reduction means under predetermined conditions; and

leakage determination means for determining that there is a leak in the evaporative fuel processing system when a variation amount of the detected pressure detected during the secondary pressure reduction by said secondary pressure reduction is higher than a predetermined leakage reference value.

2. A leakage determination system according to claim 1, wherein said secondary pressure reduction means introduces the negative pressure from the intake system at a predetermined constant negative pressure introduction flow rate.

3. A leakage determination method for an evaporative fuel processing system that causes a canister to absorb evaporative fuel generated from a fuel tank and supplies the evaporative fuel absorbed in the canister to an intake system of an internal combustion engine,

the leakage determination method comprising:

a pressure detection step of detecting pressure within the evaporative fuel processing system;

a primary pressure reduction step of primarily reducing the pressure within the evaporative fuel processing system until the detected pressure becomes equal to a predetermined negative pressure, by introducing negative pressure from the intake system;

a secondary pressure reduction step of secondarily reducing the pressure within the evaporative fuel processing system by introducing the negative pressure from the intake system successively after the primary pressure reduction at the primary pressure reduction step under predetermined conditions; and

a leakage determination step of determining that there is a leak in the evaporative fuel processing system when a variation amount of the detected pressure detected during the secondary pressure reduction is higher than a predetermined leakage reference value.

4. A leakage determination method according to claim 3, wherein at said secondary pressure reduction step, the negative pressure from the intake system is introduced at a predetermined constant negative pressure introduction flow rate.