Abstract: A system and method for detecting leakage from a evaporative emission space of an automotive vehicle fuel system. A reciprocating pump is operated in a pressurizing mode to build pressure in the space toward a nominal test pressure. The pressurizing mode involves operating the pump in a repeating cycle wherein the pump operates alternately in an accelerated pumping mode and a natural frequency pumping mode. During the pressurizing mode, a characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the space is measured. The number of times the cycle repeats is counted and compared to a predefined reference.

Abstract: A method of operating a fuel tank isolation valve and a canister vent valve. The fuel tank isolation valve has a first port, a second port, an electric actuator, and a valve body. The first port is in fluid communication with a fuel vapor collection canister. The second port is in fluid communication with a fuel tank. The electric actuator moves the valve body to control fluid communication between the first and second ports. And the canister vent valve controls ambient fluid flow with respect to the fuel vapor collection canister.

Abstract: A device for controlling fluid flow between an evaporative emission space of a fuel tank and a fuel vapor collection canister that includes a housing, a valve, a seal, an electric actuator, an electric transducer, and an electrical connector. The housing includes a first port, a second port, and a fluid flow path that extends between the first and second ports. The first port is adapted for receiving fluid flow from the evaporative emission space and is at a first pressure level. The second port is adapted for supplying fluid flow to the fuel vapor collection canister and is at a second pressure level. The valve is movable along an axis with respect to the housing between a first configuration, a second configuration, and an intermediate configuration between the first and second configurations. The first configuration permits substantially unrestricted fluid flow between the first and second ports. The second configuration prevents fluid flow between the first and second ports.

Abstract: A system and method for controlling evaporative emissions of a volatile fuel. The system preferably has a fuel vapor collection canister, a purge valve, an isolation valve, and a fuel tank. The fuel vapor collection canister includes a supply port and a discharge port. The purge valve includes an inlet port and an outlet port. The inlet port of the purge valve is in fluid communication with the discharge port of the fuel vapor collection canister. The isolation valve includes a housing, a valve body, and a seal. The housing has a first port in fluid communication with the supply port of the fuel vapor collection canister, a second port, and a fuel vapor flow path that extends between the first and second ports. The valve body is movable with respect to the housing along an axis between a first configuration and a second configuration.

Abstract: A method of operating a fuel tank isolation valve. The fuel tank isolation valve has a first port, a second port, an electric actuator, and a valve body. The first port is in fluid communication with a fuel vapor collection canister. The second port is in fluid communication with a fuel tank. And the electric actuator moves the valve body to control fluid communication between the first and second ports. The method includes supplying a first electric signal to the electric actuator such that the valve body permits substantially unrestricted fuel vapor flow between the first and second ports, supplying a second electric signal to the electric actuator such that the valve body substantially prevents fuel vapor flow between the first and second ports, and supplying a third electric signal to the electric actuator such that the valve body provides restricted fuel vapor flow between the first and second ports.

Abstract: A valve structure that includes a housing, a valve element, and a seal. The housing includes a first communication path between a first port at a first pressure level and a second port at a second pressure level. The valve element is movable with respect to the housing between a first position, a second position, and an intermediate position between the first and second positions. The first position permits substantially unrestricted fluid flow between the first and second ports. The second position substantially prevents fluid flow between the first and second ports. The seal is located at an interface between the housing and the valve element. The seal deforms in response to a differential between the first and second pressure levels such that at the intermediate position, there is restricted fluid flow between the first and second ports.

Abstract: A valve structure that includes a housing, a valve, and an actuator. The housing includes a first portion, a second portion, and an intermediate portion. The first portion extends along a first axis from a first port, the second portion extends along a second axis from a second port, and the intermediate portion connects the first and second portions. The first and second portions partially define a fluid communication path between the first and second configurations. The valve is movable with respect to the housing between first and second configurations. The first configuration permits substantially unrestricted fluid flow between the first and second ports. The second configuration substantially prevents fluid flow between the first and second ports. The actuator displaces the valve from the first configuration to the second configuration. The actuator partially defines the fluid communication path between the first and second ports.

Abstract: A system and method for controlling evaporative emissions of a volatile fuel. The system preferably has a fuel vapor collection canister, a purge valve, an isolation valve, a fuel tank, and a vent valve. The fuel vapor collection canister includes a supply port and a discharge port. The purge valve includes an inlet port and an outlet port. The inlet port of the purge valve is in fluid communication with the discharge port of the fuel vapor collection canister. The isolation valve includes a housing, a valve body, and a seal. The housing has a first port in fluid communication with the supply port of the fuel vapor collection canister, a second port, and a fuel vapor flow path that extends between the first and second ports. The valve body is movable with respect to the housing along an axis between a first configuration and a second configuration.

Abstract: In a purge mode, a purge flow path extends from atmosphere through the vent valve, through the evaporative emission space, and through the purge valve to the engine intake system. In a pre-conditioning phase of a leak verification mode, a pre-conditioning flow path extends from atmosphere through the vent valve and the purge valve to the engine intake system without passing through the evaporative emission space. In a test phase of the leak verification mode, a test path extends from the evaporative emission space through the dirty air port, through the canister medium, through the clean air port, and through the purge valve to the engine intake system.

Abstract: An on-board evaporative emission leak detection system and method that detects leakage from an evaporative emission space of a fuel system of an automotive vehicle. A test includes an initialization, or stabilization, phase during which a differential between pressure in the evaporative emission space and atmospheric pressure is created, and then varied, over time, within a range of differential pressures suitable for performing a leak detection test. This varying of pressure differential alternately increases the created pressure differential above a nominal pressure differential and decreases the created pressure differential below the nominal pressure differential. The leak detection test is then performed.

Abstract: A system and method for detecting leakage from a evaporative emission space of an automotive vehicle fuel system. A reciprocating pump is operated in a pressurizing mode to build pressure in the space toward a nominal test pressure. The pressurizing mode involves operating the pump in a repeating cycle wherein the pump operates alternately in an accelerated pumping mode and a natural frequency pumping mode. During the pressurizing mode, a characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the space is measured. The number of times the cycle repeats is counted and compared to a predefined reference.

Abstract: A leak detection system for detecting leakage from a portion of a vapor confinement space which is upstream of an inlet of a canister purge valve relative to an engine. During a test, an electric-motor-operated air pump pumps atmospheric air through a flowpath providing communication between the pump and the vapor confinement space. A flowmeter has a thermistor in the flowpath. The thermistor has a predetermined temperature vs. electric current characteristic that enables it to provide a signal correlated to flow of air through the flowpath. An electric circuit supplies and measures the electric current drawn by the thermistor to create a signal representative of the pumped airflow. The test is conducted in accordance with an algorithm that pre-heats the thermistor to a stable state before the pump is turned on. The pump is then turned on to create a predefined superatmospheric target pressure in the vapor confinement space.

Abstract: A system and method for detecting leakage from a evaporative emission space of an automotive vehicle fuel system. A reciprocating pump is operated in a pressurizing mode to build pressure in the space toward a nominal test pressure. The pressurizing mode involves operating the pump in a repeating cycle wherein the pump operates alternately in an accelerated pumping mode and a natural frequency pumping mode. During the pressurizing mode, a characteristic of successive occurrences of the natural frequency pumping mode indicative of pressure in the space is measured. The number of times the cycle repeats is counted and compared to a predefined reference.

Abstract: An on-board evaporative emission leak detection system and method that detects leakage from an evaporative emission space of a fuel system of an automotive vehicle. A test includes an initialization, or stabilization, phase during which a differential between pressure in the evaporative emission space and atmospheric pressure is created, and then varied, over time, within a range of differential pressures suitable for performing a leak detection test. This varying of pressure differential alternately increases the created pressure differential above a nominal pressure differential and decreases the created pressure differential below the nominal pressure differential. The leak detection test is then performed.

Abstract: A system and method for indicating leakage from a contained volume for holding volatile liquid, such as from an evaporative emission space of an automotive vehicle fuel system. A reciprocating pump operates to build pressure in the space toward a nominal test pressure. As the pressure is building toward nominal test pressure, but before nominal test pressure is achieved, measurements of substantially the amount of time required for the pump to execute a defined downstroke are repeatedly taken. These measurements may be referred to as pulse durations, and they are processed by an algorithm to detect when the rate of change in pulse duration changes from positive to negative, thereby defining the inflection point of a logistic curve. Subsequent measurements are taken and processed to predict a value at which substantially the pulse duration will ultimately stabilize. The predicted value is processed to indicate any leakage.

Abstract: A vapor collection canister vent valve contains both an electric pressure sensor for measuring evaporative emission space pressure during a diagnostic test and an electric actuator for operating the vent valve closed during a diagnostic test. Use of the valve in an evaporative emission control system reduces the number of connections, both electrical and fluid, that are required to install the valve in a system. The remote location of the pressure sensor damps the effect of pressure transients, such as those due to tank fuel slosh, on the sensor.

Abstract: An on-board evaporative emission leak detection system and method that detects leakage from an evaporative emission space of a fuel system of an automotive vehicle. A test includes an initialization, or stabilization, phase during which a differential between pressure in the evaporative emission space and atmospheric pressure is created, and then varied, over time, within a range of differential pressures suitable for performing a leak detection test. A leak size measurement is then obtained using an algorithm.

Abstract: A module for an on-board evaporative emission leak detection system that detects leakage from an evaporative emission space of a fuel system of an automotive vehicle. A housing provides an inlet port, an outlet port, and a flow path between the inlet port and the outlet port. An electric-motor-operated impeller pump causes flow in one direction along the flow path when in a pumping mode of operation. The pump is open to flow in both the one direction and an opposite direction when in a non-pumping mode. A solenoid-operated valve is disposed in the flow path to block flow through the flow path when in a blocking mode and to pass flow through the flow path when in a passing mode. A pressure switch is exposed to the flow path at the outlet port. A lead frame assembly provides respective electric circuit connections to the motor, solenoid, and pressure switch.

Abstract: A vapor collection canister vent valve contains both an electric pressure sensor for measuring evaporative emission space pressure during a diagnostic test and an electric actuator for operating the vent valve closed during a diagnostic test. Use of the valve in an evaporative emission control system reduces the number of connections, both electrical and fluid, that are required to install the valve in a system. The remote location of the pressure sensor damps the effect of pressure transients, such as those due to tank fuel slosh, on the sensor.