Defect diagnosing apparatus of evaporation purge system
First Claim
1. A defect diagnosing apparatus for diagnosing a defect of an evaporation purge system based on a pressure change in the evaporation purge system, said evaporation purge system having:
- a fuel tank;
a canister;
a vapor passage connecting said fuel tank and said canister; and
a purge passage connecting said canister to a suction passage connected to a combustion chamber of an engine, said apparatus comprising;
a pressure sensor connected to said evaporation purge system;
a control unit for diagnosing defect of said evaporation purge system, based on a difference between atmospheric pressure and in-system pressure of said evaporation purge system, both of atmospheric pressure and in-system pressure being detected by said pressure sensor; and
a passage switching means for switching between a plurality of passages communicating said pressure sensor to either one of said fuel tank, said canister, and the atmosphere.
1 Assignment
0 Petitions
Accused Products
Abstract
Three-way VSV switches a passage in communication with pressure sensor either to the atmosphere or to three-way VSV. The three-way VSV is provided in bypass passage connecting fuel tank with canister to switch the path to the fuel tank side or to the canister side with respect to tank internal-pressure control valve. As properly switching the three-way VSVs, the pressure sensor can detect both the pressure in the evaporation purge system and the atmospheric pressure. Upon diagnosis of defect a difference is calculated between the in-system pressure and the atmospheric pressure detected, which cancels out the dispersion or the like upon production of the pressure sensor, thus enabling to detect an accurate pressure change.
48 Citations
4 Claims
-
1. A defect diagnosing apparatus for diagnosing a defect of an evaporation purge system based on a pressure change in the evaporation purge system, said evaporation purge system having:
- a fuel tank;
a canister;
a vapor passage connecting said fuel tank and said canister; and
a purge passage connecting said canister to a suction passage connected to a combustion chamber of an engine, said apparatus comprising;a pressure sensor connected to said evaporation purge system; a control unit for diagnosing defect of said evaporation purge system, based on a difference between atmospheric pressure and in-system pressure of said evaporation purge system, both of atmospheric pressure and in-system pressure being detected by said pressure sensor; and
a passage switching means for switching between a plurality of passages communicating said pressure sensor to either one of said fuel tank, said canister, and the atmosphere. - View Dependent Claims (2)
- a fuel tank;
-
3. A defect diagnosing apparatus for diagnosing a defect of an evaporation purge system based on a pressure change in the evaporation purge system, said evaporation purge system having:
- a fuel tank;
a canister;
a vapor passage connecting said fuel tank and said canister; and
a purge passage connecting said canister to a suction passage connected to a combustion chamber of an engine, said apparatus comprising;a pressure sensor connected to said evaporation purge system; a control unit for diagnosing defect of said evaporation purge system, based on a difference between atmospheric pressure and in-system pressure of said evaporation purge system, both of atmospheric pressure and in-system pressure being detected by said pressure sensor; and
a purge control valve, disposed in said purge passage for opening or closing said purge passage, wherein said control unit further controls said purge control valve so as to cause said purge control valve to open and to cause said pressure sensor to be communicated via said suction passage to the external atmosphere when said engine has stopped.
- a fuel tank;
-
4. A defect diagnosing apparatus for diagnosing a defect of an evaporation purge system based on a pressure change in the evaporation purge system, said evaporation purge system having:
- a fuel tank;
a canister;
a vapor passage connecting said fuel tank and said canister; and
a purge passage connecting said canister to a suction passage connected to a combustion chamber of an engine, said apparatus comprising;a pressure sensor connected to said evaporation purge system; a control unit for diagnosing defect of said evaporation purge system, based on a difference between atmospheric pressure and in-system pressure of said evaporation purge system, both of atmospheric pressure and in-system pressure being detected by said pressure sensor; and
a valve, said valve forcing said canister to be opened to the atmosphere when said pressure sensor is connected to the atmosphere.
- a fuel tank;
Specification