CA2200203A1 - Sensor for measuring gas concentrations - Google Patents
Sensor for measuring gas concentrationsInfo
- Publication number
- CA2200203A1 CA2200203A1 CA 2200203 CA2200203A CA2200203A1 CA 2200203 A1 CA2200203 A1 CA 2200203A1 CA 2200203 CA2200203 CA 2200203 CA 2200203 A CA2200203 A CA 2200203A CA 2200203 A1 CA2200203 A1 CA 2200203A1
- Authority
- CA
- Canada
- Prior art keywords
- sensor
- small tube
- casing
- contact
- gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/406—Cells and probes with solid electrolytes
- G01N27/407—Cells and probes with solid electrolytes for investigating or analysing gases
- G01N27/4078—Means for sealing the sensor element in a housing
Abstract
The invention relates to a sensor for measuring gas concentrations in a gas mixture, with a tube closed at one end, along the outside of which is fitted an electric sensor contact and the open end of which is fitted in a housing, where the space along the tube between it and the housing is gastightly sealed. In order to ensure a reliable seal between the gas to be measured and the reference gas, even at high operating temperatures, and at the same time to provide several sensor funtions with high contact reliability, there are a gastight seal running peripherally between the housing and the tube at the open end of the tube forming a cold end and at least one electric sensor contact electrically insulated from the housing on the outside of the tube, and the at least one sensor contact opens into the open end of the tube and is connected to an electric line.
Description
~ 2200 203 Hanau, this September 19, 1995 SSR/Ku/kl/pO526_l.sam Patent Application Heraeus Electro-Nite international N.V.
Sensor for Measuring Gas Concentrations This invention relates to a sensor for measuring gas concentrations in a gaseous mixture including a small tube closed on one sidè on the outside of which an electrical sensor contact is arranged alongside the small tube and the end of which, opposite to the closed end is accommodated in a casing, an interspace surrounding the small tube between the casing and the small tube being sealed in gas-tight manner.
Such a gas sensor is known from US-A-3960693. A small tube including a layer acting catalytically is closed at the end pointing towards the gas to be measured and is open at its other end. It is formed thicker at this open end and is fastened in a casing. This casing is screwed into an opening of the wall of the chamber con~ining the gas to be measured, for example in internal combustion engines. The inside of the small tube communicates with the surrounding atmosphere, i.e. the reference gas. A gap is sealed off within the casing between the casing and the small tube so that the two different gases are separated from each other. The seal is made of a metal ring like the ones usually used for example with spark plugs. Gas measurements of this kind are usually carried out at high temperatures (from approximately 150~C, in the case o~ internal combustion engines from approximately 500~C upwards). The casing which is made of metal for reasons of required temperature resistance is accordingly connected conductively to the small tube, that is to say to the sensor contact. This means that the casing is integrated in the measuring circuit; the sensor is a so-called monosensor. As the seal is in a region of the sensor array which during the measurement of a combustion gas is considerably heated up, the different expansion coefficients of the casing and small tube may result in leakage and thus in measuring inaccuracies as the seal cannot compensate reliably for the different expansions. The electrical connection of the sensor contact is also m~int~ined in this hot region and can therefore only be realized with good reliability at considerable e~pense, because the contact materials tend to oxidise at high operating temperatures. The hot contact of the seal with the small tube, which may usually be made of a solid electrolyte, furthermore causes a parasitic voltage, the magnitude of which varies strongly with time because the slow o~idation or reduction of the seal cannot be controlled. This causes a considerable ~~ ~200 203 deterioration of the drift of the sensor characteristics. A similar sensor is also known from EP-A-O 520 528.
slightly different arrangement is known as a galvanic solid electrolyte celI from US-A-3399233. In this case as well, the measuring circuit is integrated into the metal casing. A gas seal is not necessary in this case, as the measurement is performed between two liquids.
A gas sensor of a different kind is known from EP-A-O 398 579. In this case a plane sensor element is provided inside a cylindrical metal casing, a ceramics powder for fixing and sealing being provided between the sensor and the casing. Leakages can occur in this case as well on heating, due to the differences in geometries between the sensor element and the casing and due to the different expansion coefficients of the materials. Especially the sealing in relation to the gas chamber to be measured is problematic. Apart from that, the sensor element can be easily damaged by vibrations occurring during operation.
Proceeding from the above described prior art the invention is based on the object to provide a sensor according to the generic type which ensures reliable sealing between the gas to be measured and the reference gas even at high operating temperatures and with which several sensor contacts, which are electrically insulated from the casing, can be realized simultaneously and where no parasitic voltages occur which impair the drift characteristics .
According to the invention the object for a sensor according to the generic clause of claim 1 is attained in that a gas-tight seal surrounding the casing and small tube is provided between them at the end which is opposite to the closed end and which presents a cold end of the small tube or a cold region, in that on the outside of the srnall tube at least one electrical sensor contact is pro~ided electrically insulated from the casing and in that the at least one sensor contact ends by leading into the closed end of the small tube opposite to the sealed end and is connected to an electrical conductor. The cold end or the cold region of the small tube is that region which is provided outside the chamber with the gas to be measured and which is removed far enough from the chamber with the gas to be measured so that it, at the most, heats up only slightly, so that the preferably used seal of electrically insulating, elastic material is not damaged and retains its elasticity. The actually required distance can be ~l~t~nined easily by a few tests and/or measurements. The connection of the sensor contacts to onward leading electrical wiring likewise takes place in such a cold region; here, the occurrence of oxidation at the contacts due to high temperature is avoided. In this case, different expansion coefficients of the materials used practically play ~ 2200 203 no role, especially in the case of elastic seals practically no thermal stresses occur so that a high sealing effect can be attained. Furthermore, parasitic and electrochemical voltages developing in the contact region between conventional metallic seals, located in the hot region, and the solid electrolyte (the small tube) can be avoided by using electrically insulating seals in the cold region. It was furthermore found that vibrations, as occur when operating motor vehicle engines or their exhaust systems are not transmitted to the sensor so that a high freedom of interference of the sensor is achieved. Conveniently, the electrical wiring can be welded or soldered to the sensor contacts and/or be pressed onto the sensor contact or contacts by means of an elastic ring. In this manner reliable contact formation is readily ~tt~in~ble.
Advantageously, a plurality of sensor contacts are provided on the outside of the small tube"~f which one or more sensor contacts may be used as heating contacts. This avoids the use of a separate heating element which in the known apparatus is pushed into a small tube. Efficiency and reaction rate of the heater are increased by this.
Conveniently, at least one electrical contact can be provided on the inside of the small tube.
In an advantageous embodiment of the invention the small tube is made of cylindrical configuration and can therefore be produced very easily. It may furthermore be advantageous to provide an electrically insulating layer on the small tube between the casing and the sensor contacts. It is furthermore possible that at least part of the outside of the small tube includes a solid electrolyte material which is electrically connected to at least one sensor contact. It is also possible to form the entire small tube of a solid electrolyte material. It is possible as well that at least part of the outside of the small tube is made of a material the electrical resistance of which depends on the gas concentration. It is collvenient in order to effectively cool the cold region that cooling ribs are arranged on the outside of the casing.
The invention will be described in detail with reference to a drawing.
The drawing shows in:
Figure 1 the small tube of the sensor with sensor contacts Figure 2 a cross section through the sensor Figure 3 the schematic representation of the sensor ~ ' 2200 203 Figure 4 another cross section through the sensor Figure S the set up of some assembly elements.
Figure 1 shows the small tube 1 of the sensor. The small tube 1 is of cylindrical configuration and closed at its one end. It is made of an electrically insulating material, for example aluminium oxide or of a solid electrolyte material, for example zirconium dioxide.
It may also be made of another material which is electrically insulated on its outside. Gas sensors 2 are provided as active elements on the outside of the small tube 1. Furthermore, an electrical heater 3 is applied onto the small tube 1. Onto these electrical sensor contacts, that is to say the gas sensors 2 and the heater 3, a thin, electrically insulating layer 4 which is, however, gas-permeable and which avoids cont~min~tion of the gas sensors 2, e.g. by exhaust constituents, has been applied. The electrical sensor contacts 2, 3 which are arranged alongside the small tube 1 end at the open side of the small tube 1, leading into so-called outer electrodes 5, by way of which the small tube 1 is electrically contacted. At the face of the open end of the small tube 1 a contact ring 6 is provided, which serves for contact formation with an electrical contact 7 provided inside of the small tube 1. This electrical contact 7 is necessary in case the gas sensor 2 is an electrochemical sensor acting with a reference gas. In this case, the reference gas is inside the small tube 1 and corresponds for example to the surrounding air. The small tube 1 is accommodated in a casing 8 as shown in figure 2. The casing 8, at its tip which holds the closed end of the small tube 1, has gas apertures 9 through which the gas to be measured reaches the gas sensors 2. In the region of the closed end of the small tube 1, the casing 8 has a nut 10 with a male thread 11, by means of which the sensor can be screwed into the wall of the chamber holding the gas to be measured. In the context of internal combustion engines this chamber may for example be part of the exhaust system (for example of motor cars). A
seal 12 may furthermore be provided at the nut 10.
The small tube 1, by way of its closed end face, abuts against the corresponding end of the casing 8 and is pressed to this end by a spring 13. The small tube 1 is spaced from the wall of the casing 8 so that the electrical sensor contacts (gas sensors 2 and heater 3) have no electrical contact with the casing 8. An O-ring 14 made of an elastic and heat-resistant plastic, for example Teflon or Viton, is provided to serve as the gas seal. This O-ring serves as a seal of the gas chamber with the gas to be measured against the atmosphere surrounding the casing 8 so that for example the surrounding air will remain separated from the exhaust fumes of an engine. The O-ring 14 furtherrnore stabilises the position of the small tube 1 within the casing 8 and secures the electrical insulation of the small tube 1 and of the sensor contacts 2, 3 of the casing 8. The O-ring 14 furthermore avoids that ~ . . -~ 2 2 0 0 2 0 3 vibrations from the casing 8 are transmitted to the small tube 1 and it compensates for the different expansion coefficients between the small tube 1 and the casing 8 so that even when heated up slightly thermal tensions cannot occur. A further O-ring 15 establishes contact of the outer electrodes 5 with the connecting leads 16. The O-ring 15 is also made of an elastic and heat-resistant plastic. The connecting leads 16 are reliably pressed onto the outer electrodes 5 by means of the O-ring 15 so that a reliable contact is ensured. It is also possible to weld the connecting leads 16 to the outer electrodes 5 or to bring a plug equipped with connecting leads 16 put on the small tube 1 into contact with the outer electrode 5.
The O-ring 15 is pressed against the O-ring 14 by the crimping piece 17 so that the small tube 1 is securely kept inside the casing 8 by it due to the additionally created tension. The pressure member 17 is pressed against the O-rings 14, 15 by means of the nut 18 via the washer 19 (of a heat-resistant plastic), the O-ring 14 being pressed against a stop face of the casing 8. The nut 18 serves to seal the inside of the casing 8, the connecting Ieads 16 as well as the connecting lead 20 are passed through this nut. The connecting leads 16, 20 are centred by the washer 19 and led through the pressure member 17 into the inside of the casing. After assembly the connecting lead 20 has electrical contact with the spring 13 which bears electrically conductive against the contact ring 6 so that the connecting lead 20 contacts the electrical contact 7 within the small tube 1. This arrangement of pressure member 17, nut 18 and washer 20 is shown enlarged and from different views in figure 5.
The use of plastic seals as O-rings 14, 15 with the resulting above described advantages is possible in an area of the casing 8 which does not heat up sigmficantly even at the operating temperature of the sensors, i.e., it only heats up so much that the plastic seals do not lose their elasticity. This region is, depending on the temperature of the gas to be measured, at least ap~lo~ ately 2 cm, especially approximately 4 cm to 6 cm distant from the seal 12 which seals off the chamber of the gas to be measured. The O-rings 14, 15 are usually fitted in a region in which the temperature is only so high that the materials of the O-rings 14, 15 can be used permanently. In order to increase the cooling effect cooling ribs 21 are arranged on the outside of the casing 8. In this manner it may be possible to decrease the distance between the rings 14, 15 and the closed end of the small tube 1. The number and shape of the cooling ribs 21 as well as the length of the casing 8 can be selected depending on the operating temperature of the gas to be measured to ensure that the so-called cold end of the small tube 1 at which the O-rings 14, 15 are fitted heats up only slightly, only to a point at which the O-rings 14, 15 are not damaged and do not lose their function.
~ ~ 2200 203 The arrangement of the cooling ribs is also shown in figures 3 and 4, figure 4 showing a longitudinal section through the sensor differing slightly from that of figure 2.
The sensor according to the invention has a ver,v simple and thus cost-effective design; it has a low interference susceptibility combined with a capability to accommodate a plurality of sensors in one casing and is thus safe in handling.
Sensor for Measuring Gas Concentrations This invention relates to a sensor for measuring gas concentrations in a gaseous mixture including a small tube closed on one sidè on the outside of which an electrical sensor contact is arranged alongside the small tube and the end of which, opposite to the closed end is accommodated in a casing, an interspace surrounding the small tube between the casing and the small tube being sealed in gas-tight manner.
Such a gas sensor is known from US-A-3960693. A small tube including a layer acting catalytically is closed at the end pointing towards the gas to be measured and is open at its other end. It is formed thicker at this open end and is fastened in a casing. This casing is screwed into an opening of the wall of the chamber con~ining the gas to be measured, for example in internal combustion engines. The inside of the small tube communicates with the surrounding atmosphere, i.e. the reference gas. A gap is sealed off within the casing between the casing and the small tube so that the two different gases are separated from each other. The seal is made of a metal ring like the ones usually used for example with spark plugs. Gas measurements of this kind are usually carried out at high temperatures (from approximately 150~C, in the case o~ internal combustion engines from approximately 500~C upwards). The casing which is made of metal for reasons of required temperature resistance is accordingly connected conductively to the small tube, that is to say to the sensor contact. This means that the casing is integrated in the measuring circuit; the sensor is a so-called monosensor. As the seal is in a region of the sensor array which during the measurement of a combustion gas is considerably heated up, the different expansion coefficients of the casing and small tube may result in leakage and thus in measuring inaccuracies as the seal cannot compensate reliably for the different expansions. The electrical connection of the sensor contact is also m~int~ined in this hot region and can therefore only be realized with good reliability at considerable e~pense, because the contact materials tend to oxidise at high operating temperatures. The hot contact of the seal with the small tube, which may usually be made of a solid electrolyte, furthermore causes a parasitic voltage, the magnitude of which varies strongly with time because the slow o~idation or reduction of the seal cannot be controlled. This causes a considerable ~~ ~200 203 deterioration of the drift of the sensor characteristics. A similar sensor is also known from EP-A-O 520 528.
slightly different arrangement is known as a galvanic solid electrolyte celI from US-A-3399233. In this case as well, the measuring circuit is integrated into the metal casing. A gas seal is not necessary in this case, as the measurement is performed between two liquids.
A gas sensor of a different kind is known from EP-A-O 398 579. In this case a plane sensor element is provided inside a cylindrical metal casing, a ceramics powder for fixing and sealing being provided between the sensor and the casing. Leakages can occur in this case as well on heating, due to the differences in geometries between the sensor element and the casing and due to the different expansion coefficients of the materials. Especially the sealing in relation to the gas chamber to be measured is problematic. Apart from that, the sensor element can be easily damaged by vibrations occurring during operation.
Proceeding from the above described prior art the invention is based on the object to provide a sensor according to the generic type which ensures reliable sealing between the gas to be measured and the reference gas even at high operating temperatures and with which several sensor contacts, which are electrically insulated from the casing, can be realized simultaneously and where no parasitic voltages occur which impair the drift characteristics .
According to the invention the object for a sensor according to the generic clause of claim 1 is attained in that a gas-tight seal surrounding the casing and small tube is provided between them at the end which is opposite to the closed end and which presents a cold end of the small tube or a cold region, in that on the outside of the srnall tube at least one electrical sensor contact is pro~ided electrically insulated from the casing and in that the at least one sensor contact ends by leading into the closed end of the small tube opposite to the sealed end and is connected to an electrical conductor. The cold end or the cold region of the small tube is that region which is provided outside the chamber with the gas to be measured and which is removed far enough from the chamber with the gas to be measured so that it, at the most, heats up only slightly, so that the preferably used seal of electrically insulating, elastic material is not damaged and retains its elasticity. The actually required distance can be ~l~t~nined easily by a few tests and/or measurements. The connection of the sensor contacts to onward leading electrical wiring likewise takes place in such a cold region; here, the occurrence of oxidation at the contacts due to high temperature is avoided. In this case, different expansion coefficients of the materials used practically play ~ 2200 203 no role, especially in the case of elastic seals practically no thermal stresses occur so that a high sealing effect can be attained. Furthermore, parasitic and electrochemical voltages developing in the contact region between conventional metallic seals, located in the hot region, and the solid electrolyte (the small tube) can be avoided by using electrically insulating seals in the cold region. It was furthermore found that vibrations, as occur when operating motor vehicle engines or their exhaust systems are not transmitted to the sensor so that a high freedom of interference of the sensor is achieved. Conveniently, the electrical wiring can be welded or soldered to the sensor contacts and/or be pressed onto the sensor contact or contacts by means of an elastic ring. In this manner reliable contact formation is readily ~tt~in~ble.
Advantageously, a plurality of sensor contacts are provided on the outside of the small tube"~f which one or more sensor contacts may be used as heating contacts. This avoids the use of a separate heating element which in the known apparatus is pushed into a small tube. Efficiency and reaction rate of the heater are increased by this.
Conveniently, at least one electrical contact can be provided on the inside of the small tube.
In an advantageous embodiment of the invention the small tube is made of cylindrical configuration and can therefore be produced very easily. It may furthermore be advantageous to provide an electrically insulating layer on the small tube between the casing and the sensor contacts. It is furthermore possible that at least part of the outside of the small tube includes a solid electrolyte material which is electrically connected to at least one sensor contact. It is also possible to form the entire small tube of a solid electrolyte material. It is possible as well that at least part of the outside of the small tube is made of a material the electrical resistance of which depends on the gas concentration. It is collvenient in order to effectively cool the cold region that cooling ribs are arranged on the outside of the casing.
The invention will be described in detail with reference to a drawing.
The drawing shows in:
Figure 1 the small tube of the sensor with sensor contacts Figure 2 a cross section through the sensor Figure 3 the schematic representation of the sensor ~ ' 2200 203 Figure 4 another cross section through the sensor Figure S the set up of some assembly elements.
Figure 1 shows the small tube 1 of the sensor. The small tube 1 is of cylindrical configuration and closed at its one end. It is made of an electrically insulating material, for example aluminium oxide or of a solid electrolyte material, for example zirconium dioxide.
It may also be made of another material which is electrically insulated on its outside. Gas sensors 2 are provided as active elements on the outside of the small tube 1. Furthermore, an electrical heater 3 is applied onto the small tube 1. Onto these electrical sensor contacts, that is to say the gas sensors 2 and the heater 3, a thin, electrically insulating layer 4 which is, however, gas-permeable and which avoids cont~min~tion of the gas sensors 2, e.g. by exhaust constituents, has been applied. The electrical sensor contacts 2, 3 which are arranged alongside the small tube 1 end at the open side of the small tube 1, leading into so-called outer electrodes 5, by way of which the small tube 1 is electrically contacted. At the face of the open end of the small tube 1 a contact ring 6 is provided, which serves for contact formation with an electrical contact 7 provided inside of the small tube 1. This electrical contact 7 is necessary in case the gas sensor 2 is an electrochemical sensor acting with a reference gas. In this case, the reference gas is inside the small tube 1 and corresponds for example to the surrounding air. The small tube 1 is accommodated in a casing 8 as shown in figure 2. The casing 8, at its tip which holds the closed end of the small tube 1, has gas apertures 9 through which the gas to be measured reaches the gas sensors 2. In the region of the closed end of the small tube 1, the casing 8 has a nut 10 with a male thread 11, by means of which the sensor can be screwed into the wall of the chamber holding the gas to be measured. In the context of internal combustion engines this chamber may for example be part of the exhaust system (for example of motor cars). A
seal 12 may furthermore be provided at the nut 10.
The small tube 1, by way of its closed end face, abuts against the corresponding end of the casing 8 and is pressed to this end by a spring 13. The small tube 1 is spaced from the wall of the casing 8 so that the electrical sensor contacts (gas sensors 2 and heater 3) have no electrical contact with the casing 8. An O-ring 14 made of an elastic and heat-resistant plastic, for example Teflon or Viton, is provided to serve as the gas seal. This O-ring serves as a seal of the gas chamber with the gas to be measured against the atmosphere surrounding the casing 8 so that for example the surrounding air will remain separated from the exhaust fumes of an engine. The O-ring 14 furtherrnore stabilises the position of the small tube 1 within the casing 8 and secures the electrical insulation of the small tube 1 and of the sensor contacts 2, 3 of the casing 8. The O-ring 14 furthermore avoids that ~ . . -~ 2 2 0 0 2 0 3 vibrations from the casing 8 are transmitted to the small tube 1 and it compensates for the different expansion coefficients between the small tube 1 and the casing 8 so that even when heated up slightly thermal tensions cannot occur. A further O-ring 15 establishes contact of the outer electrodes 5 with the connecting leads 16. The O-ring 15 is also made of an elastic and heat-resistant plastic. The connecting leads 16 are reliably pressed onto the outer electrodes 5 by means of the O-ring 15 so that a reliable contact is ensured. It is also possible to weld the connecting leads 16 to the outer electrodes 5 or to bring a plug equipped with connecting leads 16 put on the small tube 1 into contact with the outer electrode 5.
The O-ring 15 is pressed against the O-ring 14 by the crimping piece 17 so that the small tube 1 is securely kept inside the casing 8 by it due to the additionally created tension. The pressure member 17 is pressed against the O-rings 14, 15 by means of the nut 18 via the washer 19 (of a heat-resistant plastic), the O-ring 14 being pressed against a stop face of the casing 8. The nut 18 serves to seal the inside of the casing 8, the connecting Ieads 16 as well as the connecting lead 20 are passed through this nut. The connecting leads 16, 20 are centred by the washer 19 and led through the pressure member 17 into the inside of the casing. After assembly the connecting lead 20 has electrical contact with the spring 13 which bears electrically conductive against the contact ring 6 so that the connecting lead 20 contacts the electrical contact 7 within the small tube 1. This arrangement of pressure member 17, nut 18 and washer 20 is shown enlarged and from different views in figure 5.
The use of plastic seals as O-rings 14, 15 with the resulting above described advantages is possible in an area of the casing 8 which does not heat up sigmficantly even at the operating temperature of the sensors, i.e., it only heats up so much that the plastic seals do not lose their elasticity. This region is, depending on the temperature of the gas to be measured, at least ap~lo~ ately 2 cm, especially approximately 4 cm to 6 cm distant from the seal 12 which seals off the chamber of the gas to be measured. The O-rings 14, 15 are usually fitted in a region in which the temperature is only so high that the materials of the O-rings 14, 15 can be used permanently. In order to increase the cooling effect cooling ribs 21 are arranged on the outside of the casing 8. In this manner it may be possible to decrease the distance between the rings 14, 15 and the closed end of the small tube 1. The number and shape of the cooling ribs 21 as well as the length of the casing 8 can be selected depending on the operating temperature of the gas to be measured to ensure that the so-called cold end of the small tube 1 at which the O-rings 14, 15 are fitted heats up only slightly, only to a point at which the O-rings 14, 15 are not damaged and do not lose their function.
~ ~ 2200 203 The arrangement of the cooling ribs is also shown in figures 3 and 4, figure 4 showing a longitudinal section through the sensor differing slightly from that of figure 2.
The sensor according to the invention has a ver,v simple and thus cost-effective design; it has a low interference susceptibility combined with a capability to accommodate a plurality of sensors in one casing and is thus safe in handling.
Claims (11)
1. A sensor for measuring gas concentrations in a gaseous mixture including a small tube closed on one side on the outside of which an electrical sensor is arranged alongside the small tube and the end of which, opposite to the closed end is accommodated in a casing, an interspace surrounding the small tube between the casing and the small tube being sealed in gas-tight manner, characterized in that a surrounding gas-tight seal (14) between the casing (8) and the small tube (1) is made of an electrically insulating elastic material is provided at the end opposite to the closed end, which represents a cold end of the small tube (1), in that at least one electrical sensor contact (2,3) is provided electrically insulated from the casing (8) on the outside of the small tube (1) and in that the at least one sensor contact (2, 3) ends by leading into the end opposite the closed end of the small tube (1) and is connected to an electrical conductor (16).
2. A sensor according to claim 1, characterized in that the electrical conductor (16) is pressed onto the sensor contact (2, 3) by means of an elastic ring (15).
3. A sensor according to claim 1, characterized in that the electrical conductor (16) is welded to the sensor contact (2,3).
4. A sensor according to any one of claims 1 to 3, characterized in that a plurality of sensor contacts (2, 3) are arranged on the outer surface of the small tube (1), at least one sensor contact being adapted as a heating contact (3).
5. A sensor according to any one of claims 1 to 4, characterized in that at least one electrical contact (7) is arranged on the inside of the small tube (1).
6. A sensor according to any one of claims 1 to 5, characterized in that the small tube (1) is cylinder-shaped.
7. A sensor according to any one of claims 1 to 6, characterized in that an electrically insulating layer (4) is provided on the small tube (1) between the casing (8) and the sensor contacts (2, 3).
8. A sensor according to any one of claims 1 to 7, characterized in that at least part of the outer surface of the small tube (1) includes a solid electrolyte material which is connected to at least one sensor contact (2).
9. A sensor according to any one of claims 1 to 7, characterized in that the entire small tube (1) is made of a solid electrolyte material which is connected to at least one sensor contact (2).
10. A sensor according to any one of claims 1 to 7, characterized in that at least part of the outer surface of the small tube (1) includes a material the electrical resistance of which depends on the gas concentration.
11. A sensor according to any one of claims 1 to 10, characterized in that cooling ribs (21) are provided on the outside of the casing (8).
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19525942 | 1995-07-18 | ||
| DE19534918.0 | 1995-09-20 | ||
| DE19525942.4 | 1995-09-20 | ||
| DE19534918A DE19534918C2 (en) | 1995-07-18 | 1995-09-20 | Sensor for measuring gas concentrations |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2200203A1 true CA2200203A1 (en) | 1997-02-06 |
Family
ID=26016868
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2200203 Abandoned CA2200203A1 (en) | 1995-07-18 | 1996-06-28 | Sensor for measuring gas concentrations |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0781410A1 (en) |
| JP (1) | JPH10506473A (en) |
| CN (1) | CN1158164A (en) |
| AU (1) | AU708240B2 (en) |
| BR (1) | BR9606523A (en) |
| CA (1) | CA2200203A1 (en) |
| TR (1) | TR199700198T1 (en) |
| WO (1) | WO1997004306A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4192823B2 (en) * | 2003-06-06 | 2008-12-10 | 株式会社デンソー | Gas sensor |
| CA2626239C (en) * | 2005-10-19 | 2014-09-09 | Jtl Australia Pty Ltd | A slip type pipe joint |
| DE102011082260A1 (en) * | 2011-09-07 | 2013-05-08 | Robert Bosch Gmbh | Sensor for determining at least one property of a sample gas in a sample gas chamber |
| EA032158B1 (en) * | 2014-12-15 | 2019-04-30 | Открытое Акционерное Общество "Акмэ-Инжиниринг" | Sensor for sensing hydrogen in liquid and gaseous media |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4230930A (en) * | 1979-01-25 | 1980-10-28 | Ford Motor Company | Laser welding method for electrical wire connection to a terminal pin of an exhaust gas sensor |
| FR2492981A1 (en) * | 1980-07-22 | 1982-04-30 | Socapex | GAS ANALYSIS PROBE |
| DE4312506A1 (en) * | 1993-04-16 | 1994-10-20 | Bosch Gmbh Robert | Electrochemical oxygen sensor |
| DE4318789A1 (en) * | 1993-06-05 | 1994-12-08 | Bosch Gmbh Robert | Seal for a sensor element of a gas sensor |
| DE4342731B4 (en) * | 1993-07-27 | 2004-09-09 | Robert Bosch Gmbh | Electrochemical sensor with a potential-free sensor element and method for its production |
| GB2294330B (en) * | 1993-07-27 | 1997-08-06 | Bosch Gmbh Robert | Electrochemical measuring probe with a sensor element arranged in a floating manner, and process for its manufacture |
-
1996
- 1996-06-28 BR BR9606523A patent/BR9606523A/en unknown
- 1996-06-28 JP JP9506218A patent/JPH10506473A/en not_active Withdrawn
- 1996-06-28 CA CA 2200203 patent/CA2200203A1/en not_active Abandoned
- 1996-06-28 WO PCT/EP1996/002835 patent/WO1997004306A1/en not_active Application Discontinuation
- 1996-06-28 AU AU63059/96A patent/AU708240B2/en not_active Ceased
- 1996-06-28 CN CN 96190747 patent/CN1158164A/en active Pending
- 1996-06-28 EP EP96922042A patent/EP0781410A1/en not_active Withdrawn
- 1996-06-28 TR TR97/00198T patent/TR199700198T1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| AU708240B2 (en) | 1999-07-29 |
| TR199700198T1 (en) | 1997-08-21 |
| BR9606523A (en) | 1997-12-23 |
| AU6305996A (en) | 1997-02-18 |
| EP0781410A1 (en) | 1997-07-02 |
| WO1997004306A1 (en) | 1997-02-06 |
| MX9702015A (en) | 1997-11-29 |
| CN1158164A (en) | 1997-08-27 |
| JPH10506473A (en) | 1998-06-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |