WO1998008074A1 - Selective gas sensor - Google Patents
Selective gas sensor Download PDFInfo
- Publication number
- WO1998008074A1 WO1998008074A1 PCT/US1997/008567 US9708567W WO9808074A1 WO 1998008074 A1 WO1998008074 A1 WO 1998008074A1 US 9708567 W US9708567 W US 9708567W WO 9808074 A1 WO9808074 A1 WO 9808074A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- sensing element
- oxygen
- gas
- pump
- gas sensor
- Prior art date
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- 239000007789 gas Substances 0.000 claims abstract description 132
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 60
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 60
- 239000001301 oxygen Substances 0.000 claims abstract description 60
- 230000004907 flux Effects 0.000 claims abstract description 5
- 239000000919 ceramic Substances 0.000 claims description 10
- 239000012212 insulator Substances 0.000 claims description 6
- 238000005259 measurement Methods 0.000 claims 7
- 229930195733 hydrocarbon Natural products 0.000 abstract description 20
- 150000002430 hydrocarbons Chemical class 0.000 abstract description 15
- 238000009792 diffusion process Methods 0.000 abstract description 13
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Natural products C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 abstract description 13
- 150000001875 compounds Chemical class 0.000 abstract description 9
- -1 methane hydrocarbons Chemical class 0.000 abstract description 8
- 239000004215 Carbon black (E152) Substances 0.000 abstract description 7
- 230000001105 regulatory effect Effects 0.000 abstract description 2
- 239000012528 membrane Substances 0.000 description 22
- 238000012546 transfer Methods 0.000 description 17
- 229910052751 metal Inorganic materials 0.000 description 15
- 239000002184 metal Substances 0.000 description 15
- 230000003197 catalytic effect Effects 0.000 description 10
- 238000001514 detection method Methods 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 238000013461 design Methods 0.000 description 7
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 7
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 6
- 229910002091 carbon monoxide Inorganic materials 0.000 description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
- 229910052710 silicon Inorganic materials 0.000 description 5
- 239000010703 silicon Substances 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 229910001220 stainless steel Inorganic materials 0.000 description 4
- 239000010935 stainless steel Substances 0.000 description 4
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 239000003344 environmental pollutant Substances 0.000 description 3
- 238000009413 insulation Methods 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 229910052697 platinum Inorganic materials 0.000 description 3
- 231100000719 pollutant Toxicity 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 2
- 239000003570 air Substances 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910010293 ceramic material Inorganic materials 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000037361 pathway Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910052581 Si3N4 Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- MCMNRKCIXSYSNV-UHFFFAOYSA-N ZrO2 Inorganic materials O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 125000000217 alkyl group Chemical group 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000013626 chemical specie Substances 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000004035 construction material Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 239000012777 electrically insulating material Substances 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000013529 heat transfer fluid Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 239000004848 polyfunctional curative Substances 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000005368 silicate glass Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 1
- 229910001887 tin oxide Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910001928 zirconium oxide Inorganic materials 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
- G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
- G01N33/0047—Organic compounds
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/20—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity
- G01N25/22—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on combustion or catalytic oxidation, e.g. of components of gas mixtures
- G01N25/28—Investigating or analyzing materials by the use of thermal means by investigating the development of heat, i.e. calorimetry, e.g. by measuring specific heat, by measuring thermal conductivity on combustion or catalytic oxidation, e.g. of components of gas mixtures the rise in temperature of the gases resulting from combustion being measured directly
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0011—Sample conditioning
- G01N33/0016—Sample conditioning by regulating a physical variable, e.g. pressure or temperature
Definitions
- This invention relates, in general, to gas component sensors, and more particularly, to gas sensors containing a sensing element showing temperature dependent selectivity for various components of a high temperature gas stream.
- Sensors for the detection of particular compounds present in a high temperature gas stream find numerous applications in many different mechanical systems. For example, detection of certain compounds in a high temperature gas stream is important in industrial emission monitoring for detection of gas pollutants, such as sulfur dioxide (S ⁇ 2), in residential heating systems for detection of carbon monoxide (CO), and in automobile exhaust systems for various compounds including hydrocarbons. In automotive applications, gas sensors can be placed at various locations in an exhaust system.
- gas pollutants such as sulfur dioxide (S ⁇ 2)
- CO carbon monoxide
- gas sensors can be placed at various locations in an exhaust system.
- Exhaust gas from an internal combustion engine typically contains hydrogen (H2), carbon monoxide (CO), methane (CH4), carbon dioxide (CO2), nitric oxide (NO), water (H2O), and non-methane hydrocarbons (C n H m ), where n is an integer larger than 1 and m is an integer whose value depends upon the kind of hydrocarbon compound, for example, alkane, alkene, alkyl, or aryl.
- Important environmental pollution concerns dictate that the emission of hydrocarbons be minimized.
- sensors can be placed before and after the catalytic converter to monitor the performance of the converter.
- the emission of hydrocarbons can be controlled, in part, by an engine exhaust control system that receives a feedback signal from an exhaust sensor capable of selectively detecting the presence of hydrocarbons in the engine exhaust.
- a gas sensor For proper operation, a gas sensor must be built to operate within the high temperature and corrosive environment of a gas stream emerging from one of the mechanical systems described above.
- the sensor must contain a sensing element capable of selectively detecting the presence of a particular compound.
- a sensing element capable of selectively detecting the presence of a particular compound.
- hydrocarbons having a molecular weight greater than methane.
- sensing elements include calorimetric sensors having a catalyst coating, semiconductor metal oxide based sensors, mixed-potential electrochemical sensors, or amperometric electrochemical sensors.
- the gas sensing elements disclosed in the prior art typically exhibit higher selectivity to detection of non-methane hydrocarbons within specific temperature ranges.
- the sensing element performs best in a specific temperature range, the temperature of the gas stream into which the sensor is submerged often varies over time.
- automobile engine operation is dynamic and the exhaust gas temperature varies from ambient temperature at engine start-up to more than 1000°C during periods of high power operation.
- the temperature of the exhaust gas within the exhaust system changes with distance from the engine.
- the temperature range of maximum non-methane hydrocarbon sensitivity is below the temperature of the automobile exhaust gas stream during normal engine operation after warm-up, yet above ambient temperatures.
- calorimetric sensors require an oxygen source for the catalytic oxidation of the hydrocarbons on a sensitive region of the sensing element.
- oxygen supply systems used in catalytic gas sensors operate at a temperature that exceeds the temperature range of maximum hydrocarbon selectivity for the sensor.
- the best performance of the sensing element is obtained at a temperature that is below both the operating temperature of the electrochemical oxygen pump and the steady-state temperature of the exhaust gas stream.
- Efficient operation of a selective gas sensor requires that the sensor housing be designed to maintain the sensing element at its optimum operating temperature. Accordingly, a need existed for an improved sensor design that maintains optimum operating efficiency of a selective sensing element.
- FIG. 1 is a schematic block diagram of a selective gas sensor having independent temperature control zones arranged in accordance with the invention
- FIG. 2 is an exploded assembly view of a selective gas sensor arranged in accordance with one embodiment of the invention
- FIG. 3 is an inverted perspective view of a heat pipe assembled in accordance with one embodiment of the invention.
- FIG. 4 is a cross-section of the selective gas sensor shown in FIG.
- the present invention is for a selective gas sensor capable of detecting the presence of a particular component in a high temperature gas stream.
- the selective gas sensor is configured to maintain separate regions of the sensor at different temperatures, and to maintain temperature gradients within the sensor.
- a calorimetric sensing element is employed to determine the presence of non-methane hydrocarbons by sensing the heat given off when hydrocarbons are oxidized on the sensor.
- the selective gas sensor described herein effectively accommodates the conflicting operating temperatures of the oxygen pump and the sensing element, while both are immersed in a high temperature gas stream.
- the selective gas sensor of the invention can be employed in other applications, such as the detection of CO in a building heating system, S ⁇ 2 emissions from a coal fired power plant, and the like.
- FIG. 1 Shown in FIG. 1 is a schematic block diagram illustrating the regions of thermal management within a selective gas sensor 10 of the invention.
- the sensor is immersed in a high temperature gas stream 12.
- gas stream 12 is an engine exhaust emerging from an internal combustion engine.
- Gas stream 12 passes through selective sensor 10 at a temperature typically ranging from ambient air temperature at engine start to 1150°C at high power output.
- the exhaust temperature is usually between 500°C and 800°C.
- the gas sensor temperature would eventually become equal to the temperature of the gas stream, or some other temperature between that of the gas stream and the oxygen pump.
- selective gas sensor 10 employs at least five distinct thermal management zones.
- a high temperature oxygen generation system 14 is separated from a sensing element 16 by an oxygen diffusion region 15 and a medial temperature control zone 20.
- Sensing element 16 is further temperature controlled by an external temperature control zone 22.
- the thermal regions identified in FIG. 1 function to maintain the temperature of sensing element 16 at its most effective operating temperature. For example, at a temperature below about 400 to 600°C, sensing element 16 exhibits maximum sensing selectivity to hydrocarbons having a molecular weight exceeding that of methane. Meanwhile, the electrochemical oxygen pump used in high temperature oxygen generation system 14 most effectively operates at a temperature of about 800°C. Accordingly, the thermal management regions function to maintain a large temperature gradient while selective sensor 10 is immersed in a gas stream having an average temperature intermediate to that of the electrochemical oxygen pump and the hydrocarbon sensing element.
- medial temperature control zone 20 primarily functions to provide sensing element 16 with a small, representative sample of the high temperature gas stream entering selective sensor 10. By limiting the quantity of gas impinging on sensing element 16, less heat is available to be transferred from the gas to the sensing element.
- external temperature control zone 22 functions to conductively cool sensing element 16.
- the temperature control zones provide thermal management of both the gas stream impinging upon the sensing element and the temperature of the sensing element itself.
- Oxygen diffusion region 15 provides both an oxygen diffusion pathway and thermal insulation between the electrochemical oxygen pump and the sensing element.
- FIG. 2 illustrates an assembly view of a selective sensor 10 arranged in accordance with one embodiment of the invention.
- a sensing element 16 is mounted on a heat transfer surface 24 of a thermally conductive heat pipe 26.
- heat pipe 26 is constructed of a material having a large heat capacity to minimize and dampen temperature fluctuation of the gases in second chamber 64 and of sensing element 16.
- heat pipe 26 can be material having a high thermal conductivity, such as copper, stainless steel, and the like.
- heat pipe 26 can be constructed of an electrically insulating material, such as alumina.
- heat pipe 26 encloses a plurality of ceramic rods 28 that provide conduits for electrical wires 30.
- Sensing element 16 is a silicon micromachined sensor having sensing components integrated together on a silicon chip. Sensing element 16 is preferably a calorimetric catalytic sensor. This type of catalytic gas sensor typically employs a differential calorimeter. Each individual member includes a heater element and a thermometer element overlying a thin-film area. The thin-film area is formed by depositing a layer of silicon dioxide or silicon nitride on a silicon substrate, then etching away a portion of the silicon substrate to expose the underside of the deposited thin-film. A catalyst material, such as platinum (Pt), palladium (Pd), gold (Au), and the like, is deposited onto the temperature measurement element to catalyze an oxidation reaction.
- Pt platinum
- Pd palladium
- Au gold
- sensing element 16 can be a Taguchi-type gas sensor employing a metal oxide, such as tin oxide (Sn ⁇ 2).
- a semiconductor metal oxide base sensor is disclosed in, for example, U.S. Patent 4,033,169.
- An electrochemical oxygen pump 32 and pump housing 34 are positioned over a gas-permeable membrane 36.
- a mechanical support frame 38 encloses electrochemical oxygen pump 32, pump housing 34, and gas permeable membrane 36.
- a thermal insulator ring 40 fits over mechanical support frame 38 and provides thermal insulation between mechanical support frame 38 and a threaded metal housing 42. Threaded metal housing 42 couples with a support tube 44 to enclose the sensor elements and to strengthen the housing assembly.
- support tube 44 is constructed a material having low thermal conductance, such as from stainless steel, in order to suppress heat flow from threaded metal housing 42 into heat pipe 26.
- heat pipe 26 can be optionally fitted with a plurality of disks 46.
- Disks 46 are orthogonally connected to heat pipe 26 and are thermally coupled to the heat pipe such that an expanded heat transfer surface is provided.
- FIG. 3 An inverted perspective view of heat pipe 26 and related components is shown in FIG. 3.
- a bottom plate 48 is attached to the most distal heat transfer disk and surrounds the bottom surface 50 of heat pipe 26.
- the terminal ends of electrical wires 30, carried by ceramic rods 28, are exposed at bottom surface 50.
- Electrical wires 30 can be coupled to external electronic circuitry (not shown) by making electrical connections at bottom surface 50.
- thermally conductive bodies can be utilized to perform a heat transfer function.
- FIGs. 2 and 3 provides a description of one embodiment of a thermally conductive body
- heat pipe 26 can be a fully functional heat exchanger employing a heat transfer fluid mechanically pumped through the heat pipe, or an electric cooling system, or the like.
- heat pipe 26 can be constructed of materials having lower thermal conductivity, such as alumina, silicate glass, and the like.
- the outer wall of heat pipe 26 can be textured, or bifurcated, to expand the surface area of the heat pipe.
- FIG. 4 A cross-sectional view of the assembly illustrated in FIG. 2 taken along section line 4-4 and mechanically attached to a metal wall is shown in FIG. 4.
- Threaded metal housing 42 engages a threaded boss 52 inserted into a metal wall 54.
- Metal housing 42 contains a plurality of gas ports 56 through which gas stream 12 can flow.
- mechanical support frame 38 contains gas ports 58 that cooperate with gas ports 56 and oxygen pump support 34 to provide a passage for the flow of gas stream 12 past membrane 36 and oxygen pump 32.
- Membrane 36 spans an interior cavity 60 within support frame
- membrane 36 is preferably a thermally insulating, gas-permeable member through which a selected component of gas stream 12 can diffuse.
- membrane 36 can be a porous ceramic plate, or a ceramic sheet having perforations in the sheet allowing for the flow of gas stream 12 through the perforations.
- membrane 36 regulates the flux of the constituents of gas stream 12 to the surface of sensing element 16.
- membrane 36 can be a porous polymer material.
- Oxygen pump 32 has an upper electrode 67 exposed to gas stream 12 and a lower electrode 68 facing an oxygen storage chamber 70 housed within pump support 34.
- a heating element 33 overlies upper electrode 67 and is separated from the upper electrode by an insulating portion of pump housing 34. Heating element 33 resistively heats oxygen pump 32 by passing electrical current through a convoluted pattern of platinum leads overlying the pump housing.
- oxygen pump 32 extracts oxygen atoms by the electro-dissociation of oxygen containing compounds within gas stream 12. The oxygen obtained from the oxygen containing compounds is conducted to lower surface 68 where oxygen is released into oxygen storage chamber 70.
- Oxygen storage chamber 70 provides a reservoir of oxygen available to supply large amounts of oxygen to second chamber 64 for a brief period of time, while simultaneously collecting oxygen produced by the slow, steady-state operation of oxygen pump 32.
- a diffusion conduit 72 provides a pathway for the diffusion of oxygen from oxygen storage chamber 70 to second chamber 64.
- oxygen pump 32 is a conventional electrochemical pump including an oxygen-ion conducting solid electrolyte sandwiched between two platinum electrodes.
- the electrolyte is a zirconia compound, such as yttria-doped zirconium oxide (Y, Z1O2).
- Oxygen pumped from gas stream 12 to oxygen storage chamber 70 can diffuse through diffusion conduit 72 to second chamber 64.
- diffusion conduit 72 is filled with a porous material to suppress the backflow of gas components from gas stream 12.
- pump support 34 also provides thermal insulation between the high temperature oxygen pump and the lower temperature gas within second chamber 64.
- pump support 34 is a solid ceramic material resistant to the diffusion of gas species.
- Oxygen diffused to second chamber .64 through conduit 72 mixes with the selected gas diffusing through membrane 36 into second chamber 64 and oxidizes the gaseous compound at the surface of sensing element 16.
- the corrosion of electrical wires 30, shown in FIG. 2, by the oxidative environment within second chamber 64 is prevented by covering electrical wires 30 and the bonding pads of sensing element 16 (not shown) with a protective material 74.
- the operation of the embodiment illustrated in FIG. 4 in relation to the gas dynamics of gas stream 12 and the thermal management zones illustrated in FIG. 1 will now be described.
- the proper function of selective gas sensor 10 requires that the sensor housing be designed such that a small, representative mass of a selected gas be brought in contact with sensing element 16 at a high flow rate.
- Rapid movement of gas through the passages and chambers of gas sensor 10 is important to minimize repsonse time required for changes in component concentrations within gas stream 12 to be reflected in the gas volume in the vacinity of sensing element 16.
- rapid gas flow is important to minimize the amount of heat transfer that occurs between the gas and the sensor components.
- heat conduction from high temperature components, such as electrochemical oxygen pump 32 must be minimized.
- the component arrangement illustrated in FIG. 4 represents one method for providing the proper mass transfer and heat transfer characteristics necessary for the highly selective detection of a selected gas, such as non-methane hydrocarbons within gas stream 12.
- high temperature oxygen generation system 14 is represented by oxygen pump 32.
- Oxygen diffusion region 15 is represented by pump support 34.
- Medial temperature control zone 20 is represented by mechanical support frame 38, and by gas- permeable membrane 36.
- external temperature control zone 22 is represented by heat pipe 26 and thermal insulator ring 40.
- the maintenance of the separate thermal control zones illustrated in FIG. 1 requires careful selection of construction materials for the various components of selective sensor 10. For example, thermal conduction of threaded metal housing 42 should be minimized, however this element must provide adequate mechanical strength to protect the internal components of selective gas sensor 10 and provide a mounting support for attachment of the gas sensor to a metal wall, such as an automobile exhaust pipe.
- threaded metal housing 42 is constructed from high strength steel.
- Mechanical support frame 38 must provide mechanical support and protection for the oxygen pumping and diffusion systems and protect sensing element 16 from contamination by corrosive components within gas stream 12.
- mechanical support frame 38 is a ceramic element.
- support frame 38 has been illustrated with gas ports 58 for the flow of selected gas into cavity 60, mechanical support frame 38 can also be a porous ceramic material through which selected gases can diffuse into cavity 60.
- Thermal insulator ring 40 must minimize the heat flow from threaded metal housing 42 and provide a gas impermeable barrier to prevent the leakage of gas stream 12 outward from metal wall 54 and along heat pipe 26. Insulator ring 40 is held in place by a circumferential groove 43 in housing 42. Preferably, thermal insulator ring 40 is a ceramic ring coated with a surface hardener. Gas permeable membrane 36 functions as a mass transport barrier that limits the flux of selected gases entering second chamber 64 and contacting sensing element 16. In order to maintain a stable relationship between the gas flux entering second chamber 64 and the concentration of selected gas in gas stream 12, membrane 36 is fabricated to withstand high temperature and corrosive gases. Preferably, membrane 36 is constructed from porous ceramic or stainless steel frit.
- the temperature of the membrane is stabilized to minimize temperature-dependent gas diffusivity through the membrane. Temperature stability is provided by maintaining good thermal contact to heat pipe 26 through mechanical support frame 38, and by maximizing the thermal mass of the membrane. Additionally, the temperature of membrane 36 may be controlled by a heater (not shown) either embedded in or placed in proximity to the membrane.
- the volume of second chamber 64 can be minimized or eliminated entirely when it is desirable to reduce the time required for sensing element 16 to respond to concentration changes in gas stream 12.
- the distance between sensing element 16 and membrane 36 can be increased when it is desirable to reduce the heat transfer from membrane 36 to sensing element 16.
- sensing element 16 is in solid thermal contact with heat transfer surface 24.
- sensing element 16 is attached to heat transfer surface 24 with a thermally conductive adhesive (not shown).
- Support tube 44 is preferably thin-walled stainless steel to minimize its thermal conductance in order to suppress heat flow from metal housing 42 to the most proximal disc 46. Additionally, tube 44 encloses a volume 70 in an annular space between the tube wall and heat pipe 26. Volume 70 can be filled with air or another thermally insulative material to suppress heat flow from tube 44 onto heat pipe 26.
- sensing element 16 can be configured for the detection of CO and metal wall 54 can be a furnace exhaust gas duct.
- sensing element 16 can be configured to detect S ⁇ 2 or another gas pollutant commonly found in industrial emissions.
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- Pathology (AREA)
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Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97925660A EP0859951A4 (en) | 1996-08-14 | 1997-05-21 | Selective gas sensor |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/696,550 US5689059A (en) | 1996-08-14 | 1996-08-14 | Selective gas sensor |
US08/696,550 | 1996-08-14 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998008074A1 true WO1998008074A1 (en) | 1998-02-26 |
Family
ID=24797526
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1997/008567 WO1998008074A1 (en) | 1996-08-14 | 1997-05-21 | Selective gas sensor |
Country Status (3)
Country | Link |
---|---|
US (1) | US5689059A (en) |
EP (1) | EP0859951A4 (en) |
WO (1) | WO1998008074A1 (en) |
Families Citing this family (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6242263B1 (en) | 1996-12-20 | 2001-06-05 | Corning Incorporated | Automotive hydrocarbon sensor |
US6015533A (en) * | 1997-11-14 | 2000-01-18 | Motorola Inc. | Sensor housing for a calorimetric gas sensor |
US6071476A (en) * | 1997-11-14 | 2000-06-06 | Motorola, Inc. | Exhaust gas sensor |
DE19830709C2 (en) * | 1998-07-09 | 2002-10-31 | Daimler Chrysler Ag | Measuring transducer for the detection of hydrocarbons in gases |
US6344173B1 (en) | 1998-12-07 | 2002-02-05 | Corning Incorporated | Automotive hydrocarbon sensor |
GB9920170D0 (en) * | 1999-08-25 | 1999-10-27 | Univ Portsmouth | A passive sampling device |
WO2001020314A1 (en) * | 1999-09-10 | 2001-03-22 | Heraeus Electro-Nite International N.V. | Gas sensor for determining reducing gases in a gas mixture |
JP2002005868A (en) * | 2000-06-16 | 2002-01-09 | Yamatake Corp | Detector |
US6691553B2 (en) * | 2000-08-29 | 2004-02-17 | Delphi Technologies, Inc. | Gas sensor protective shield |
US6579030B2 (en) | 2001-05-15 | 2003-06-17 | Arvinmeritor, Inc. | Sensor mount assembly |
US6719950B2 (en) | 2001-11-14 | 2004-04-13 | Robert Bosch Corporation | Miniaturized exhaust gas sensor |
DE10302738B4 (en) * | 2003-01-23 | 2016-12-15 | Vaillant Gmbh | Exhaust gas sensor device |
US20040231441A1 (en) * | 2003-05-23 | 2004-11-25 | Ceradex Corporation | Structure for oxygen sensor of vehicles |
US7611612B2 (en) | 2005-07-14 | 2009-11-03 | Ceramatec, Inc. | Multilayer ceramic NOx gas sensor device |
JP5179545B2 (en) * | 2010-07-06 | 2013-04-10 | 日本特殊陶業株式会社 | Gas sensor |
DE102011011631B4 (en) * | 2011-02-17 | 2014-10-16 | Continental Automotive Gmbh | Tank device for storing a liquid pollutant-reducing medium |
DE102011012682A1 (en) * | 2011-03-01 | 2012-09-06 | Hella Kgaa Hueck & Co. | Gas sensor, especially for automotive applications |
US10197519B2 (en) * | 2013-03-15 | 2019-02-05 | H2Scan Corporation | Gas sensing systems and methods |
DE102014111506A1 (en) | 2014-08-12 | 2016-02-18 | Analytik Jena Ag | Analyzer for determining a measure dependent on the concentration of one or more ingredients of a sample |
JP7123837B2 (en) * | 2019-03-15 | 2022-08-23 | 日本特殊陶業株式会社 | gas sensor |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5505837A (en) * | 1993-04-10 | 1996-04-09 | Robert Bosch Gmbh | Sensor arrangement for determining gas components and/or gas concentrations of gas mixtures |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3607084A (en) * | 1968-12-02 | 1971-09-21 | Sun Electric Corp | Combustible gas measurement |
JPS5119592A (en) * | 1974-08-09 | 1976-02-16 | Nissan Motor | Gasunodo kenshutsuki |
US3906721A (en) * | 1974-08-22 | 1975-09-23 | Gen Motors Corp | Thermoelectric exhaust gas sensor |
US4244918A (en) * | 1975-12-23 | 1981-01-13 | Nippon Soken, Inc. | Gas component detection apparatus |
JPS56141541A (en) * | 1980-04-07 | 1981-11-05 | Yamatake Honeywell Co Ltd | Calorific value measuring device |
JPS56141546A (en) * | 1980-04-07 | 1981-11-05 | Yamatake Honeywell Co Ltd | Calorific value measuring device |
JPH0810211B2 (en) * | 1986-09-05 | 1996-01-31 | 日本碍子株式会社 | Gas sensor and manufacturing method thereof |
JP2636883B2 (en) * | 1988-04-30 | 1997-07-30 | 日本碍子株式会社 | NOx concentration measuring device |
JP2876793B2 (en) * | 1991-02-04 | 1999-03-31 | トヨタ自動車株式会社 | Semiconductor type hydrocarbon sensor |
US5250169A (en) * | 1991-06-07 | 1993-10-05 | Ford Motor Company | Apparatus for sensing hydrocarbons and carbon monoxide |
DE4311849C2 (en) * | 1992-12-23 | 2003-04-24 | Bosch Gmbh Robert | Sensor for determining gas components and / or gas concentrations in gas mixtures |
DE4324659C1 (en) * | 1993-07-22 | 1995-04-06 | Siemens Ag | Sensor with a sensor element arranged in a housing |
-
1996
- 1996-08-14 US US08/696,550 patent/US5689059A/en not_active Expired - Fee Related
-
1997
- 1997-05-21 EP EP97925660A patent/EP0859951A4/en not_active Withdrawn
- 1997-05-21 WO PCT/US1997/008567 patent/WO1998008074A1/en not_active Application Discontinuation
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5505837A (en) * | 1993-04-10 | 1996-04-09 | Robert Bosch Gmbh | Sensor arrangement for determining gas components and/or gas concentrations of gas mixtures |
Also Published As
Publication number | Publication date |
---|---|
EP0859951A1 (en) | 1998-08-26 |
EP0859951A4 (en) | 2000-12-27 |
US5689059A (en) | 1997-11-18 |
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