Apparatus for detecting malfunction in evaporated fuel purge system
First Claim
1. An apparatus for detecting a malfunction in an evaporated fuel purge system, said evaporated fuel purge system including a canister for absorbing fuel vapor fed from a fuel tank to the canister via a vapor passage, a purge passage for connecting the canister to an intake passage of an engine, and a purge control valve provided in the purge passage, said purge control valve being opened when the engine is operating under a predetermined operating condition, whereby fuel vapor is fed from the canister to the intake passage via the purge passage, said apparatus comprising:
- first means for subjecting said system to a negative pressure in the intake passage by opening the purge control valve thereby connecting the canister to the intake passage via the purge passage, and for subsequently closing the purge control valve to maintain said negative pressure in said system for a predetermined time period by disconnecting the purge passage from the intake passage and disconnecting the canister from the atmosphere during the predetermined time period,pressure sensing means for sensing a pressure in said system independently of the operation of said first means; and
discrimination means for detecting whether or not a malfunction has occurred in said system, in response to a difference between pressures sensed by said pressure sensing means respectively at a beginning of said predetermined time period and at an end thereof.
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Accused Products
Abstract
An apparatus for detecting a malfunction in an evaporated fuel purge system, includes a diagnosis control valve provided in an air inlet passage connecting an air inlet of a canister to the atmosphere, a pressure sensor provided at an intermediate portion of a vapor passage between a fuel tank and a purge control valve for sensing a pressure in the vapor passage, and a control part for controlling opening and closing operations of both the purge control valve and the diagnosis control valve. In this apparatus, the purge control valve is opened and the diagnosis control valve is closed by the control part under a predetermined operating condition of an engine, the purge control valve being closed after the vapor passage is subjected to a negative pressure in an intake passage of the engine, the negative pressure being maintained during a predetermined time period, the apparatus thus detecting whether or not a malfunction has occurred in the system, in response to a difference between pressures sensed by the pressure sensor respectively at a beginning of the predetermined time period and at an end thereof.
54 Citations
8 Claims
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1. An apparatus for detecting a malfunction in an evaporated fuel purge system, said evaporated fuel purge system including a canister for absorbing fuel vapor fed from a fuel tank to the canister via a vapor passage, a purge passage for connecting the canister to an intake passage of an engine, and a purge control valve provided in the purge passage, said purge control valve being opened when the engine is operating under a predetermined operating condition, whereby fuel vapor is fed from the canister to the intake passage via the purge passage, said apparatus comprising:
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first means for subjecting said system to a negative pressure in the intake passage by opening the purge control valve thereby connecting the canister to the intake passage via the purge passage, and for subsequently closing the purge control valve to maintain said negative pressure in said system for a predetermined time period by disconnecting the purge passage from the intake passage and disconnecting the canister from the atmosphere during the predetermined time period, pressure sensing means for sensing a pressure in said system independently of the operation of said first means; and discrimination means for detecting whether or not a malfunction has occurred in said system, in response to a difference between pressures sensed by said pressure sensing means respectively at a beginning of said predetermined time period and at an end thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification