Evaporative emission leak detection system
First Claim
1. In an engine-powered automotive vehicle evaporative emission control system comprising an evaporative emission space for containing volatile fuel vapors, and a leak detection system for detecting leakage from the evaporative emission space, the improvement in said leak detection system which comprises:
- a prime mover for pumping gaseous fluid with respect to the evaporative emission space;
a selectively operable valve assembly which operates to a first condition for allowing the prime mover to pump gaseous fluid with respect to the evaporative emission space, which operates to a second condition for closing the evaporative emission space upon attainment of an initial test pressure within the evaporative emission space that differs sufficiently from atmospheric pressure to allow a leak in the evaporative emission space to be detected, and which operates to a third condition different from its first and second conditions;
a control, including a pressure-responsive electric device, for controlling operation of the prime mover and the valve assembly;
wherein the pressure-responsive electric device is disposed to provide an electric signal related to pressure in the evaporative emission space;
wherein the pressure-responsive electric device allows the valve assembly to assume its first condition while the prime mover is operated to pressurize the evaporative emission space to an initial test pressure at the beginning of a test;
wherein a signal from the pressure-responsive device causes the valve assembly to assume its second condition upon attainment of the initial test pressure; and
wherein a signal from the pressure-responsive device causes the valve assembly to assume its third condition when the initial test pressure has changed by a pre-defined amount due to a leak in the evaporative emission space.
1 Assignment
0 Petitions
Accused Products
Abstract
An on-board diagnostic system for an evaporative emission control system of an internal combustion engine powered vehicle employs a leak detection module that is fluid connected in a vent passage for the evaporative emission space. The leak detection module contains an electric motor driven impeller, a solenoid operated valve assembly that is selectively operable to three positions, and a pressure-responsive switch whose switching characteristic possesses hysteresis corresponding to an upper regulating limit and a lower regulating limit. The valve assembly operates to allow the prime mover to pump gaseous fluid with respect to the evaporative emission space to attain a test pressure in the evaporative emission space corresponding to the upper regulating limit, to close the evaporative emission space and prevent the prime mover from pumping gaseous fluid with respect to the evaporative emission space upon initially attaining the upper regulating limit test pressure within the evaporative emission space, and which allows the prime mover to pump gaseous fluid with respect to the evaporative emission space at a pre-defined volumetric flow rate to rebuild pressure in the evaporative emission space to the upper regulating limit when the pressure has changed to the lower regulating limit due to a leak in the evaporative emission space.
-
Citations
27 Claims
-
1. In an engine-powered automotive vehicle evaporative emission control system comprising an evaporative emission space for containing volatile fuel vapors, and a leak detection system for detecting leakage from the evaporative emission space, the improvement in said leak detection system which comprises:
-
a prime mover for pumping gaseous fluid with respect to the evaporative emission space; a selectively operable valve assembly which operates to a first condition for allowing the prime mover to pump gaseous fluid with respect to the evaporative emission space, which operates to a second condition for closing the evaporative emission space upon attainment of an initial test pressure within the evaporative emission space that differs sufficiently from atmospheric pressure to allow a leak in the evaporative emission space to be detected, and which operates to a third condition different from its first and second conditions; a control, including a pressure-responsive electric device, for controlling operation of the prime mover and the valve assembly; wherein the pressure-responsive electric device is disposed to provide an electric signal related to pressure in the evaporative emission space; wherein the pressure-responsive electric device allows the valve assembly to assume its first condition while the prime mover is operated to pressurize the evaporative emission space to an initial test pressure at the beginning of a test; wherein a signal from the pressure-responsive device causes the valve assembly to assume its second condition upon attainment of the initial test pressure; and wherein a signal from the pressure-responsive device causes the valve assembly to assume its third condition when the initial test pressure has changed by a pre-defined amount due to a leak in the evaporative emission space. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. In an engine-powered automotive vehicle evaporative emission control system comprising an evaporative emission space for containing volatile fuel vapors, and a leak detection system for detecting leakage from the evaporative emission space, the improvement in said leak detection system which comprises:
-
a prime mover for pumping gaseous fluid with respect to the evaporative emission space; a selectively operable valve assembly which is in series flow relationship with the prime mover and operates to allow the prime mover to pump gaseous fluid through the valve assembly with the respect to the evaporative emission space, to close the evaporative emission space and prevent the prime mover from pumping gaseous fluid with respect to the evaporative emission space upon attainment of an initial test pressure within the evaporative emission space that differs sufficiently from atmospheric pressure to allow a leak in the evaporative emission space to be detected, and which allows the prime mover to pump gaseous fluid through the valve assembly with respect to the evaporative emission space at a pre-defined volumetric flow rate to rebuild pressure in the evaporative emission space to the initial test pressure when the pressure has changed from the initial test pressure by a pre-defined amount due to a leak in the evaporative emission space. - View Dependent Claims (19, 20, 21)
-
-
22. 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, the module comprising:
-
a housing having an inlet port, an outlet port, and a flow path extending between the inlet port and the outlet port; the housing containing a selectively operable pump disposed in the flow path and capable of causing flow in one direction along the flow path when in a pumping mode of operation;
the pump being open to flow in both the one direction and an opposite direction when in a non-pumping mode;the housing containing a selectively operable valve 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; and the housing containing a sensor exposed to the flow path. - View Dependent Claims (23, 24, 25)
-
-
26. 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, the module comprising:
-
a housing having an inlet port, an outlet port, and a flow path between the inlet port and the outlet port; a selectively operable pump assembly that is disposed in the flow path; a selectively operable valve assembly that is disposed in the flow path; each of the pump assembly and the valve assembly comprising a respective electric device for operating the respective assembly, the housing comprising plural receptacles disposed side-by-side and having spaced apart parallel axes, the electric device for the pump assembly being disposed coaxially in a first of the receptacles and the electric device for the valve assembly being disposed coaxially in a second of the receptacles; and the housing comprising plural housing parts that are in assembly relationship to cooperatively define the first and second receptacles and enclose the pump and valve assemblies within the housing.
-
-
27. 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, the assembly comprising:
-
a housing having an inlet port, an outlet port, and a flow path between the inlet port and the outlet port; a selectively operable pump assembly that is disposed in the flow path; a selectively operable valve assembly that is disposed is the flow path; each of the pump assembly and the valve assembly comprising a respective electric device for operating the respective assembly, the housing comprising plural receptacles having spaced apart parallel axes, the electric device for the pump assembly being disposed coaxially in a second of the receptacles and the electric device for the valve assembly being disposed coaxially in a second of the receptacles; and the housing comprising plural housing parts that are in assembly relationship to cooperatively define the first and second receptacle and enclose the pump and valve assemblies within the housing, the housing comprising a third receptacle, and including a sensor disposed within the third receptacle and fluid-communication to the flow path.
-
Specification