Leak detection system for sealed beam headlamp units

Claim 2

A leak detection system for a sealed beam headlamp unit having a gas fill including helium, said leak detection system comprising: a device operative to detect helium; a test chamber adapted to receive said unit; means for evacuating said test chamber to thereby draw said gas fill including helium through any unit leakage paths into said chamber; means for injecting a carrier gas into said test chamber after evacuating the latter, said gas admixing with any gas fill that has leaked from the unit; first checking means operably connected to said test chamber for indicating if the pressure in said chamber is above a first predetermined value indicative of a high rate of leakage; a cold trap operative to condense the carrier gas and the gas fill other than helium; means fluidly connecting said test chamber with said cold trap if the pressure in said test chamber as indicated by said first checking means is below said first predetermined value; second checking means operatively connected to said cold trap for indicating when the pressure thereat is above a second predetermined value indicative of a high rate of leakage but lower than said first predetermined value; means fluidly connecting said cold trap with said device if the pressure at said cold trap as indicated by said second checking means is below said second predetermined value whereby said first and second checks prevent excessive ingestion of helium at the device.

Claim 3

A leak detection system for a sealed beam headlamp unit including a volume of tracer gas, said leak detection system comprising: a device operative to detect said tracer gas; a test chamber adapted to receive said unit; a fluid line fluidly connected between the test chamber and said device; condensing means in said fluid line for condensing gases having a boiling point higher than the tracer gas; means for evacuating said test chamber for drawing said tracer gas through any unit leakage paths into said chamber; a source of a carrier gas having a boiling point higher than tracer gas; means for injecting the carrier into said test chamber after evacuating the latter for admixing with any tracer gas that has leaked from the unit; checking means operably connected to said fluid line for indicating if said pressure in said chamber is above a predetermined value indicative of a high rate of leakage; valve means in said fluid line for fluidly connecting said test chamber with said device only if the pressure in said test chamber as indicated by said checking means is below said predetermined value.

Claim 4

A leak detection system for a sealed beam headlamp unit including a volume of tracer gas, said leak detection system comprising: a device operative to detect said tracer gas; a test chamber adapted to receive said unit; a fluid line fluidly connected between the test chamber and said device; condensing means in said fluid line for condensing gases having a boiling point higher than the tracer gas; means for evacuating said test chamber for drawing said tracer gas through any unit leakage paths into said chamber; a source of a carrier gas having a boiling point higher than tracer gas; means for injecting the carrier into said test chamber after evacuating the latter for admixing with any tracer gas that has leaked from the unit; checking means operably connected to said fluid line for indicating if said pressure in said chamber is above a predetermined value indicative of a high rate of leakage; valve means in said fluid line for fluidly connecting said test chamber with said device only if the pressure in said test chamber as indicated by said checking means is below said predetermined value.

Claim 5

A leak detection system for a sealed beam headlamp unit having a gas fill including helium, said leak detection system comprising: a cold trap operative to condense carbon dioxide; a mass spectrometer operative to detect helium in excess of a calibrated amount; a test chamber adapted to receive said unit, said chamber having an interior cavity closely conforming to said unit; a vacuum line serially fluidly connecting the cavity, the cold trap and the mass spectrometer; a source of helium; means for delivering a calibrated leakage of helium from said source to said cavity; a vacuum pump for evacuating said cavity to thereby draw said gas fill including helium into said cavity through any leakage paths in the unit; a source of carbon dioxide; valve means for injecting a metered volume of carbon dioxide into said cavity after the latter is evacuated for admixing with any gas fill that has leaked from the unit and said calibrated leakage of helium; a first vacuum gauge operably connected to said cavity for indicating if said pressure therein is above a first predetermined value indicative of a high rate of leakage; a first valve in said vacuum line prior to the cold trap, said first valve being operative to connect the cavity with said cold trap if the pressure in said cavity as indicated by said first vacuum gauge is below said first predetermined value; a second vacuum gauge operatively connected to said cold trap, said second vacuum gauge indicating when the pressure thereat is above a second predetermined value indicative of a high rate of leakage but lower than said first predetermined value; a second valve in said vacuum line prior to the mass spectrometer for connecting the cold trap with the mass spectrometer if the pressure at said cold trap as indicated by said second vacuum gauge is below said second predetermined value whereby said first and second gauges and valves cooperate to prevent the mass spectrometer from being fluidly exposed to excessive helium from high rate leaking units.

Claim 6

A leak detection system for a sealed beam headlamp unit having a gas fill including helium, said leak detection system comprising: a cold trap operative to condense carbon dioxide; a mass spectrometer operative to detect helium in excess of a calibrated amount; a test chamber adapted to receive said unit, said chamber having an interior cavity closely conforming to said unit; a vacuum line serially fluidly connecting the cavity, the cold trap and the mass spectrometer; a source of helium; means for delivering a calibrated leakage of helium from said source to said cavity; a vacuum pump for evacuating said cavity to thereby draw said gas fill including helium into said cavity through any leakage paths in the unit; a source of carbon dioxide; valve means for injecting a metered volume of carbon dioxide into said cavity after the latter is evacuated for admixing with any gas fill that has leaked from the unit and said calibrated leakage of helium; a first vacuum gauge operably connected to said cavity for indicating if said pressure therein is above a first predetermined value indicative of a high rate of leakage; a first valve in said vacuum line prior to the cold trap, said first valve being operative to connect the cavity with said cold trap if the pressure in said cavity as indicated by said first vacuum gauge is below said first predetermined value; a second vacuum gauge operatively connected to said cold trap, said second vacuum gauge indicating when the pressure thereat is above a second predetermined value indicative of a high rate of leakage but lower than said first predetermined value; a second valve in said vacuum line prior to the mass spectrometer for connecting the cold trap with the mass spectrometer if the pressure at said cold trap as indicated by said second vacuum gauge is below said second predetermined value whereby said first and second gauges and valves cooperate to prevent the mass spectrometer from being fluidly exposed to excessive helium from high rate leaking units.