Fuel vapor leak test system and method comprising successive series of pulse bursts and pressure measurements between bursts
First Claim
1. A leak test system for a motor vehicle fuel system that holds volatile liquid fuel for operating the vehicle, the leak test system comprising:
- a processor for establishing steps of a leak test that comprises an initial pressurization phase followed by a measurement phase;
a pump for forcing air under pressure into vapor containment space of the fuel system during a leak test;
a pump operator that operates the pump in accordance with steps established by the processor to cause the pump to create a superatmospheric pressure in the space during the initial pressurization phase of the leak test, and that, after completion of the initial pressurization phase and regardless of any leakage, causes the pump to perform the measurement phase of the leak test that comprises forcing pulses of air into the space in a succession of pulse bursts, wherein each burst comprises a succession of individual pulses of air in substantially equal numbers of pulses, and each successive burst is delayed from an immediately prior burst by substantially the same amount of time that is substantially longer than the time intervals between individual pulses in each burst whereby each burst and the ensuing delay until the next burst define a substantially constant duty cycle of pump operation that is independent of pressure in the vapor containment space; and
wherein the processor processes data corresponding to a measurement of pressure in the space after the occurrence of at least one of such bursts and as a result of that processing indicates whether leakage from the space is occurring.
1 Assignment
0 Petitions
Accused Products
Abstract
A leak test system and method for a motor vehicle fuel system. A pump forces air under pressure into vapor containment space. The pump operates in accordance with steps established by a processor. The pump creates superatmospheric pressure in the space during an initial charging phase step, and after completion of that step, the pump performs a measurement phase step that forces pulses of air into the space in a succession of pulse bursts. Each burst contains a succession of individual pulses, preferably in equal numbers, and each successive burst is delayed from an immediately prior burst by a time interval substantially longer than the time intervals between individual pulses in each burst, preferably by constant time intervals. The processor processes data corresponding to a measurement of pressure in the space after the occurrence of at least one of such bursts and as a result indicates leakage from the space.
-
Citations
31 Claims
-
1. A leak test system for a motor vehicle fuel system that holds volatile liquid fuel for operating the vehicle, the leak test system comprising:
-
a processor for establishing steps of a leak test that comprises an initial pressurization phase followed by a measurement phase;
a pump for forcing air under pressure into vapor containment space of the fuel system during a leak test;
a pump operator that operates the pump in accordance with steps established by the processor to cause the pump to create a superatmospheric pressure in the space during the initial pressurization phase of the leak test, and that, after completion of the initial pressurization phase and regardless of any leakage, causes the pump to perform the measurement phase of the leak test that comprises forcing pulses of air into the space in a succession of pulse bursts, wherein each burst comprises a succession of individual pulses of air in substantially equal numbers of pulses, and each successive burst is delayed from an immediately prior burst by substantially the same amount of time that is substantially longer than the time intervals between individual pulses in each burst whereby each burst and the ensuing delay until the next burst define a substantially constant duty cycle of pump operation that is independent of pressure in the vapor containment space; and
wherein the processor processes data corresponding to a measurement of pressure in the space after the occurrence of at least one of such bursts and as a result of that processing indicates whether leakage from the space is occurring. - View Dependent Claims (2, 3, 5, 6)
-
-
7. A leak test system for a motor vehicle fuel system that holds volatile liquid fuel for operating the vehicle, the leak test system comprising:
-
a processor for establishing steps of a leak test;
a pump for forcing air under pressure into vapor containment space of the fuel system during a leak test;
a pump operator that operates the pump in accordance with steps established by the processor to cause the pump to create a superatmospheric pressure in the space during an initial step of the leak test, and that, after completion of the initial step, causes the pump to perform a further step that comprises forcing pulses of air into the space in a succession of pulse bursts, wherein each burst comprises a succession of individual pulses of air, and each successive burst is delayed from an immediately prior burst by a time interval substantially longer than the time intervals between individual pulses in each burst; and
wherein the processor processes data corresponding to a measurement of pressure in the space after the occurrence of at least one of such bursts and as a result of that processing indicates leakage from the space, and during the initial step of the leak test, the processor performs a pressure progress test to ascertain if pressure is increasing sufficiently fast in the space to allow a valid leak test to be completed within an amount of time allotted for the leak test, and wherein the pressure progress test comprises the processor processing data corresponding to a measurement of pressure in the space and data defining an intermediate pressure representing a measure of progress in creating suitable superatmospheric pressure in the space that will enable the leak test to be performed within the amount of time allotted for the leak test, and if the latter processing discloses that pressure in the space is not less than the intermediate pressure, the processor allows the leak test to continue. - View Dependent Claims (4, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A leak test method for a motor vehicle fuel system that holds volatile liquid fuel for operating the vehicle, the method comprising:
-
forcing air under pressure into vapor containment space of the fuel system during an initial pressurization phase and a subsequent measurement phase of a leak test in accordance with steps of the method;
wherein during the initial pressurization phase, the forcing of air into the space creates in the space a superatmospheric pressure suitable for performing the leak test; and
after completion of the initial pressurization phase and regardless of any leakage, operating a pump to perform the measurement phase of the leak test that comprises forcing pulses of air into the space in a succession of pulse bursts, wherein each burst comprises a succession of individual pulses of air in substantially equal numbers of pulses, and each successive burst is delayed from an immediately prior burst by substantially the same amount of time that is substantially longer than the time intervals between individual pulses in each burst whereby each burst and the ensuing delay until the next burst define a substantially constant duty cycle of pump operation that is independent of pressure in the vapor containment space; and
processing data corresponding to a measurement of pressure in the space after the occurrence of at least one of such bursts and as a result of that processing, indicating whether leakage from the space is occurring. - View Dependent Claims (16, 17, 18, 19, 20, 21)
-
-
22. A leak test method for a motor vehicle fuel system that holds volatile liquid fuel for operating the vehicle, the method comprising:
-
forcing air under pressure into vapor containment space of the fuel system during a leak test in accordance with steps of the method;
wherein during an initial step of the method, the forcing of air into the space creates in the space a superatmospheric pressure suitable for performing the leak test; and
after completion of the initial step, operating a pump to perform a further step of the method that comprises forcing pulses of air into the space in a succession of pulse bursts, wherein each burst comprises a succession of individual pulses of air, and each successive burst is delayed from an immediately prior burst by a time interval substantially longer than the time intervals between individual pulses in each burst; and
processing data corresponding to a measurement of pressure in the space after the occurrence of at least one of such bursts and indicating leakage from the space as a result of that processing, including the step of performing a pressure progress test during the initial step of the leak test to ascertain if pressure is increasing sufficiently fast in the space to allow a valid leak test to be completed within an amount of time allotted for the leak test, wherein the step of performing a pressure progress test comprises processing data corresponding to a measurement of pressure in the space and data defining an intermediate pressure representing a measure of progress in creating suitable superatmospheric pressure in the space that will enable the leak test to be performed within the amount of time allotted for the leak test, and if the latter processing discloses that pressure in the space is not less than the intermediate pressure, allowing the leak test to continue. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29)
-
-
30. A leak test system for a motor vehicle fuel system that holds volatile liquid fuel for operating the vehicle, the leak test system comprising:
-
a processor for establishing steps of a leak test;
a pump for forcing air under pressure into vapor containment space of the fuel system during a leak test;
a pump operator that operates the pump in accordance with steps established by the processor to cause the pump to create a superatmospheric pressure in the space during an initial step of the leak test, and that, after completion of the initial step and regardless of any leakage, causes the pump to perform a further step that comprises forcing pulses of air into the space in a succession of pulse bursts, wherein each burst comprises a succession of individual pulses of air, and each successive burst is delayed from an immediately prior burst by a time interval substantially longer than the time intervals between individual pulses in each burst;
wherein the processor processes data corresponding to a measurement of pressure in the space after the occurrence of at least one of such bursts and as a result of that processing indicates whether leakage from the space is occurring; and
wherein the processor indicates no leakage from the space when a result of the processing discloses an increase in pressure.
-
-
31. A leak test method for a motor vehicle fuel system that holds volatile liquid fuel for operating the vehicle, the method comprising:
-
forcing air under pressure into vapor containment space of the fuel system during a leak test in accordance with steps of the method;
wherein during an initial step of the method, the forcing of air into the space creates in the space a superatmospheric pressure suitable for performing the leak test; and
after completion of the initial step and regardless of any leakage, operating a pump to perform a further step of the method that comprises forcing pulses of air into the space in a succession of pulse bursts, wherein each burst comprises a succession of individual pulses of air, and each successive burst is delayed from an immediately prior burst by a time interval substantially longer than the time intervals between individual pulses in each burst;
processing data corresponding to a measurement of pressure in the space after the occurrence of at least one of such bursts and as a result of that processing, indicating whether leakage from the space is occurring; and
wherein the step of indicating whether leakage from the space is occurring comprises indicating no leakage from the space when a result of the processing discloses an increase in pressure.
-
Specification