摘要:
A diagnostic method and system includes a control valve configured to control an amount of air drawn into an evaporative emissions (EVAP) system through an air filter and a vapor canister, and a pressure sensor configured to measure pressure in the EVAP system. The system also includes a controller configured to detect an engine idle-to-off transition and, in response to detecting the engine idle-to-off transition: receive a first pressure from the pressure sensor, fully open a purge valve connected between the vapor canister and an intake port of an engine, fully close the control valve, monitor one or more second pressures received from the pressure sensor, and detect a malfunction of the EVAP system based on the first pressure, at least one of the one or more second pressures, and a diagnostic threshold.
摘要:
An evaporative emissions (EVAP) control system for a vehicle includes a purge pump configured to pump fuel vapor to an engine of the vehicle via a vapor line and a purge valve. The system includes a hydrocarbon (HC) sensor disposed in the vapor line and configured to measure an amount of HC in the fuel vapor pumped by the purge pump to the engine via the vapor line. A controller is configured to: detect an imminent cold start of the engine and, in response to the detecting, perform the cold start of the engine by controlling at least one of the purge pump and the purge valve, based on the measured amount of HC, to deliver a desired amount of fuel vapor to the engine, which decreases HC emissions by the engine.
摘要:
A method is provided for detecting a very small leak in an evaporative emission control system of an automotive vehicle. The method includes sealing the evaporative emission control system at a key-off event and monitoring a vacuum switch coupled to the evaporative emission control system for a closing event due to a natural vacuum created in the evaporative emission control system as it cools. If the closing event is not detected, the method determines if a leak detection timer has exceeded a predetermined threshold value. If the timer has exceeded the predetermined threshold value, the method sets a fault code indicating that the very small leak has been detected. Preferably, the leak detection timer includes a first time value corresponding to an amount of time the automotive vehicle has been operating since a previous small leak detection test was conducted and a second time value corresponding to an amount of time the automotive vehicle has been inoperative since a previous small leak detection test was conducted. The first time value includes a series of individual trip times of the automotive vehicle while the second time value includes a series of individual inoperative session times of the automotive vehicle.
摘要:
A method of pinched line detection for an evaporative emission control system to determine if a pinched line is present within the system includes the steps of pulsing a leak detection pump at a predetermined rate and determining if a last pump period is less than a predetermined possible pinched line period limit. The method also includes the steps of concluding a possible pinched line if the last pump period is not less than the possible pinched line period limit and concluding that there is not a possible pinched line if the last pump period is greater than or equal to the possible pinched line period limit.
摘要:
A leak detection assembly for an evaporative emission control system in an automotive vehicle including a fuel tank, a canister for collecting volatile fuel vapors from the fuel tank, a purge valve disposed between the canister and an intake manifold of an engine operative to allow flow of the fuel vapors from the canister to the intake manifold, a vacuum actuated pump in communication with the canister, and a vent control valve operative to selectively allow and prevent communication between the canister and an atmospheric vent of the vacuum actuated pump, the leak detection assembly including a three-port solenoid fluidly connected to the intake manifold and a second atmospheric vent, and a vacuum line fluidly connecting the three-port solenoid to the vent control valve, the three-port solenoid selectively communicating with the intake manifold to allow a vacuum in the vacuum line during a first operating mode to close the vent control valve and selectively communicating with the second atmospheric vent during a second operating mode to open the vent control valve.
摘要:
A diagnostic method and system includes a control valve configured to control an amount of air drawn into an evaporative emissions (EVAP) system through an air filter and a vapor canister, and a pressure sensor configured to measure pressure in the EVAP system. The system also includes a controller configured to detect an engine idle-to-off transition and, in response to detecting the engine idle-to-off transition: receive a first pressure from the pressure sensor, fully open a purge valve connected between the vapor canister and an intake port of an engine, fully close the control valve, monitor one or more second pressures received from the pressure sensor, and detect a malfunction of the EVAP system based on the first pressure, at least one of the one or more second pressures, and a diagnostic threshold.
摘要:
An evaporative emissions (EVAP) control system for a vehicle includes a purge pump configured to pump fuel vapor trapped in a vapor canister to an engine of the vehicle via a vapor line when engine vacuum is less than an appropriate level for delivering fuel vapor to the engine, the fuel vapor resulting from evaporation of a liquid fuel stored in a fuel tank of the engine. The EVAP control system includes a hydrocarbon (HC) sensor disposed in the vapor line and configured to measure an amount of HC in the fuel vapor pumped by the purge pump to the engine via the vapor line. The EVAP control system also includes a controller configured to, based on the measured amount of HC, control at least one of the purge pump and a purge valve to deliver a desired amount of fuel vapor to the engine.
摘要:
A boost purge ejector tee arrangement for a fuel vapor emissions system can include a boost purge ejector tee having a body that can define a first inlet port, a second inlet port and an outlet port. The first inlet port and the outlet port can be fluidly coupled along a first flow path. The body can define a second flow path from the second inlet port that can intersect the first flow path upstream of the outlet port. A nozzle can be positioned in the first flow path such that an outlet of the nozzle can be proximate the intersection of the second flow path with the first flow path. The boost purge ejector tee can be integrated into an air box that can be associated with an engine such that the outlet port exits into an inside of the air box.
摘要:
A method is provided for cleansing a seal of a device used for sealing an evaporative emission control system of an automotive vehicle. The method starts by determining if a request to close the device has been made. If the request to close the device has been made, the method cycles the device a plurality of times to press and lift the seal off of a seat repeatedly. The method also determines if the seal is closed after the cycling step. If the seal is not closed after the cycling step, the method closes the seal. Preferably, the cycling step includes cycling the device at a pre-selected duty cycle, frequency and cycle count. The duty cycle, frequency, and cycle count correspond to calibration tables prepared for the particular device employed to insure that the seal strikes its seat about three times before sealing.
摘要:
A loose or missing fuel cap detection method for an evaporative emission control system of an automotive vehicle detects a loose or missing fuel cap based in part on whether fuel level changed. The method determines whether the fuel level changed, which is indicative of a refueling event. The method then determines if one or more leaks are present. If the fuel level changed and one or more leaks are present, the method determines that the fuel cap is loose or missing.