CN101097209A - Limiting current type oxygen sensor and method of sensing and measuring oxygen concentrations using the same - Google Patents
Limiting current type oxygen sensor and method of sensing and measuring oxygen concentrations using the same Download PDFInfo
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Abstract
A limiting current type oxygen sensor comprises an ion conductor, a pair of electrodes, a gas diffusion mechanism for supplying a diffusion-rate-determined gas, and a heater for heating the ion conductor. The gas diffusion mechanism includes a gas diffusion bore and an internal space communicating with the gas diffusion bore. In a first embodiment, the gas diffusion mechanism is configured such that the thickness (lin) of the internal space is formed equal to or larger than the bore diameter (S1) of the gas diffusion bore. This makes it possible to dominate diffusion-rate-determinateness in the gas diffusion bore and minimize the influence of diffusion-rate-determinateness in the internal space, thereby sensing the limiting current value accurately. In a second embodiment, the gas diffusion mechanism is configured such that an oxygen concentration gradient within the internal space satisfies the following expression: 1/I lim = (1/4FDC o2 ){(l/S) + (l in /S in )} which is based on a relationship between the Faraday constant (F); a diffusion coefficient (D); an oxygen concentration (C o2 ); a bore area (S) of the gas diffusion bore; a bore length (1) in the axial direction of the gas diffusion bore; a distance (l in ) in the internal space between the first elextrode and the inner surface opposed thereto; an effective cross section (S in ) of the internal space; and an output current value (I lim ).
Description
The present invention requires the right of priority of the Japanese patent application submitted on June 27th, 2006 2006-176882 number and 2006-176883 number, and the content of these patents is incorporated this paper by reference into.
Technical field
The present invention relates to be used for sensing and measure the limit-current type oxygen sensor of oxygen concentration and with the method for this lambda sensor sensing and measurement oxygen concentration.
Background technology
As is generally known, limit-current type oxygen sensor can use by for example using yttria (Y
2O
3) the stable zirconia (zirconia of stabilized with yttrium oxide: the YSZ) ion conductor of solid electrolyte formation of adjuvant.Figure 10 is the synoptic diagram of the conventional limit-current type oxygen sensor structure of explanation.As shown in figure 10, general conventional limit-current type oxygen sensor 100 comprises that the anode electrode 102 of the ion conductor 101 of solid electrolyte, the porosint that forms and cathode electrode 103 are to apply leap monitoring voltage therebetween on the ion conductor both sides.Form gas diffuser in the lid 106 that links to each other with ion conductor, it has gas diffusion hole 104,105 and inner space 106a, is provided to an electrode 103 rate of diffusion is limited gas.
Provide well heater 107 in the outside of lid 106, ion conductor 101 is set in hundreds of degrees centigrade monitor temperature.Well heater 107 links to each other with lead 108.Form described gas diffusion hole 104 by lid 106 towards electrode 103, and form described gas diffusion hole 105 along electrode 103 surfaces by lid.Widely used limit-current type oxygen sensor is not comprise one of gas diffusion hole 105,106, for example, is not included in the type of the gas diffusion hole 105 that wherein forms.
The monitoring voltage of the feasible leap electrode 102,103 that applies of the structure of limit-current type oxygen sensor 100 can make the output current and the voltage that flow in ion conductor 101 proportional when low-voltage.Another feature of limit-current type oxygen sensor 100 is that output current is saturated when monitoring voltage raises.Output current in the saturation region is called the restriction electric current.The restriction current's intensity has certain relation with oxygen concentration.Therefore, by the limiting current value that obtains according to monitoring voltage, limit-current type oxygen sensor 100 can sensing and the concentration of measuring oxygen.
The electric current that flows in the ion conductor 101 of limit-current type oxygen sensor 100 is based on the migration of oxonium ion, and has the current value that depends on voltage and temperature.Therefore, limit-current type oxygen sensor 100 is set in about 400～500 ℃ monitor temperature and by driven.Usually, by on the lid 106 of limit-current type oxygen sensor 100 or sensor body part, well heater 107 being provided and, setting monitor temperature to its energising.
Such limit-current type oxygen sensor 100 drives by the method that applies the monitoring voltage of crossing over electrode 102,103, and under many circumstances, well heater 107 is switched on always and (for example, seen patent documentation 1: Jap.P. 3373741).In order to improve at sensing and output current value when measuring than low oxygen concentration, so the limit-current type oxygen sensor 100 of the routine of structure provides gas diffuser, and described gas diffuser not only comprises gas diffusion hole 104 but also comprises the gas diffusion hole 105 that forms by lid 106.
In the limit-current type oxygen sensor 100 with the gas diffuser that is configured to comprise the gas diffusion hole 104,105 that bore portion for example forms by lid 106, the structure gas diffuser satisfies the condition of expression (1) to measure the concentration of oxygen:
[expression formula 1]
Be hole area (S), gas stagnation pressure (P), gas law constant (R), temperature (T), the hole length (L) of bore portion, the partial pressure of oxygen (P of Faraday constant (F), coefficient of diffusion (D), bore portion
O2) and output current value (IL) between relation.
In this limit-current type oxygen sensor, gas diffuser can be configured to make electrode and and its interior surface opposing between distance in the inner space, promptly inner space 106a is in the aperture of the thickness of gas diffusion hole 104 on axially less than gas diffusion hole 104.Under this condition, output current value shows following feature as shown in figure 11.Accompanying drawing 11 is the figure of voltage (V)-electric current (I) feature in the limit-current type oxygen sensor of this class routine of expression.As shown in Figure 11, if the thickness of inner space is less than the aperture of gas diffusion hole in the gas diffuser of limit-current type oxygen sensor, the relation between bias voltage (Vs) and the output current (Is) has the feature shown in the solid line 111 in the sensor so.Just, if the thickness of inner space is less, the oxygen molecule that diffuses into the inner space by gas diffusion hole also is the rate of diffusion restriction in the inner space before arriving the cathode electrode end.Therefore, the flat region 112 on the solid line 111 shows bigger vertical bank feature (not being steady state value).Therefore, in the limit-current type oxygen sensor of routine, have this feature according to the limiting current value of monitoring voltage, and based on this value sensing with measure the concentration of oxygen.So the limit-current type oxygen sensor with inner space of less thickness has the feature that concerns the flat region that medium dip is bigger at voltage-to-current.Therefore, the fluctuation of monitoring voltage, fluctuating or variation destroy the accuracy of sensing limiting current value, and the feasible exact value that is difficult to obtain limiting electric current.
In the limit-current type oxygen sensor 100 of above-mentioned routine, except gas diffusion hole 104, sensing and measurement also need to form new gas diffusion hole 105 by lid 106 than low oxygen concentration.This needs the procedure of processing of greater number in the process of producing limit-current type oxygen sensor 100, and makes sensor construction itself complicated, thereby causes increasing production cost.
In addition, in limit-current type oxygen sensor 100, the surface (electrode surface) of the electrode 103 on the ion conductor 101 forms new gas diffusion hole 105 by lid.Therefore, compare, depend on machining precision, be easy to cause the bigger variation of production precision with being not included in the type that wherein forms gas diffusion hole 105.Therefore cause the variation of slant characteristic, and the measuring accuracy instability.
In addition, aperture that can enlargement gas diffusion hole 104, rather than as the limit-current type oxygen sensor of the routine in above-mentioned patent documentation 1, described in gas diffusion hole 105, and can not provide gas diffusion hole 105.In this sensor, oxygen concentration be 1% or lower restriction Current Zone in, the limiting current value may not satisfy the condition of above-mentioned expression formula (1).Therefore, accurate sensing and measure oxygen concentration.
Summary of the invention
The present invention has considered these problems, and purpose provides the limit-current type oxygen sensor that can improve sensing limiting current value degree of accuracy.Another object of the present invention provides limit-current type oxygen sensor, itself in addition can be accurately under lower oxygen concentration and sensing and measure oxygen concentration admirably, and it is easy to make, and prevents the variation of above-mentioned slant characteristic, and reduces cost.The present invention also provides the method for using described limit-current type oxygen sensor sensing and measuring oxygen concentration.
One embodiment of the invention provide a kind of limit-current type oxygen sensor, comprise the ion conductor that is made of solid electrolyte; The porous electrode that is arranged on the ion conductor is right, is used for applying betwixt electric field; Be configured to rate of diffusion is limited the gas diffuser on surface that gas is provided to an electrode of electrode pair; With the well heater that is configured to heat described ion conductor, wherein said gas diffuser comprises the inner space that contacts with the surface of an electrode of described electrode pair and forms to be communicated with the gas diffusion hole of inner space and sensor outside, wherein form gas diffuser make electrode and and its interior surface opposing between distance in the inner space more than or equal to the aperture of gas diffusion hole.Gas diffuser can comprise a plurality of described gas diffusion holes and the inner space that communicates with described a plurality of gas diffusion holes, wherein form gas diffuser and make the distance in the inner space be equal to or greater than all diameter sums of described a plurality of gas diffusion holes, or be equal to or greater than the value of calculating by the effective cross section of described a plurality of gas diffusion holes.
In another embodiment of the invention, a kind of limit-current type oxygen sensor is provided, comprise the ion conductor that constitutes by solid electrolyte; The porous electrode that is arranged on the ion conductor is right, is used for applying betwixt electric field; Be configured to rate of diffusion is limited the gas diffuser on surface that gas is provided to an electrode of electrode pair; With the well heater that is configured to heat described ion conductor, wherein said gas diffuser comprises the inner space that contacts with the surface of an electrode of described electrode pair, with the gas diffusion hole that forms with connection inner space and sensor outside, wherein construct described gas diffuser and make the oxygen concentration gradient in the inner space satisfy following expression:
1/I
lim＝(1/4FDC
o2){(l/S)+(l
in/S
in)}
This expression formula is based on Faraday constant (F), coefficient of diffusion (D), oxygen concentration (C
O2), in the hole length (l) on axially of the hole area (S) of gas diffusion hole, gas diffusion hole, inner space electrode and and its interior surface opposing between distance (l
In), the effective cross section (S of inner space
In) and output current value (I
Lim) between relation.Can form gas diffuser make electrode in the inner space and and its interior surface opposing between distance more than or equal to the aperture of gas diffusion hole.Can construct gas diffuser and make that the hole area (S) of gas diffusion hole and the ratio (S/l) of hole length (l) are 50～250 μ m.
The present invention also provides a kind of operating limit current oxygen sensors sensing and measures the method for oxygen concentration, described sensor comprises the ion conductor that is made of solid electrolyte, be arranged on porous electrode on the ion conductor to apply electric field betwixt, structure is to limit rate of diffusion the gas diffuser on surface that gas is provided to an electrode of electrode pair, with the well heater that is configured to heat described ion conductor, described method is included in the inner space that formation contacts with the surface of an electrode of electrode pair in the gas diffuser and forms the gas diffusion hole that is communicated with inner space and sensor outside; By calculating the condition that the oxygen concentration gradient that makes in the inner space satisfies expression, come sensing and measure oxygen concentration:
1/I
lim＝(1/4FDC
o2){(l/S)+(l
in/S
in)}
Described expression formula is based on Faraday constant (F), coefficient of diffusion (D), oxygen concentration (C
O2), in the hole length (l) on axially of the hole area (S) of described gas diffusion hole, gas diffusion hole, described inner space electrode and and its interior surface opposing between distance (l
In), the effective cross section (S of described inner space
In) and output current value (I
Lim) between relation.
According to one embodiment of the invention, gas diffuser comprises that the inner space that contacts with an electrode of electrode pair and formation are so that the gas diffusion hole of inner space and sensor external communications.Form gas diffuser make electrode in the inner space and and its interior surface opposing between distance more than or equal to the aperture of gas diffusion hole.Therefore, the restrictive influence of rate of diffusion in the inner space of its energy minimization sensor, and the accurate limiting current value of sensing.
According to another embodiment of the invention, gas diffuser comprises that the inner space that contacts with an electrode of electrode pair and formation are so that the gas diffusion hole of inner space and sensor external communications.The structure gas diffuser makes the oxygen concentration gradient in the inner space satisfy a certain expression formula.Therefore, compare with the conventional sensors that provides a plurality of gas diffusion holes, the processing of gas diffusion hole is easier.In addition, based on the concentration gradient that satisfies a certain expression formula condition, sensing and measure oxygen concentration accurately.This can in addition 1% or lower than under the low oxygen concentration, sensing and measure oxygen concentration accurately and admirably, and be easy to produce prevents the variation of precision machining characteristic, and reduces production costs.
Description of drawings
Fig. 1 is the synoptic diagram that shows according to the limit-current type oxygen sensor structure of first embodiment of the invention.
Fig. 2 is the stereographic map of the limit-current type oxygen sensor seen from the arrow A direction among Fig. 1.
Fig. 3 is the stereographic map of the limit-current type oxygen sensor seen from the arrow B direction among Fig. 1.
Fig. 4 is the figure that shows voltage (V)-electric current (I) feature of limit-current type oxygen sensor.
Fig. 5 is presented under the atmosphere of certain oxygen concentration, has the figure of voltage (V)-electric current (I) feature of the limit-current type oxygen sensor of different-thickness inner space in gas diffuser.
Fig. 6 is that expression is according to the figure that concerns between the hole area of gas diffusion hole in the limit-current type oxygen sensor of second embodiment of the invention and hole length and the output current.
Fig. 7 is the figure that concerns between the hole area of gas diffusion hole and hole length and the output current in the expression limit-current type oxygen sensor.
Fig. 8 is the figure that shows voltage (V)-electric current (I) feature of limit-current type oxygen sensor.
Fig. 9 is the figure that shows the gas concentration feature of limit-current type oxygen sensor.
Figure 10 is the synoptic diagram that shows the structure of conventional limit-current type oxygen sensor.
Figure 11 is the figure that shows voltage (V)-electric current (I) feature of conventional limit-current type oxygen sensor.
Embodiment
Hereinafter with reference to the limit-current type oxygen sensor of description of drawings according to first embodiment of the present invention and second embodiment.
[first embodiment]
Shown in Fig. 1～3, limit-current type oxygen sensor 10 according to first embodiment of the invention comprises the ion conductor 11 that is made of solid electrolyte, electrode 12a, the 12b of electrode pair, setting is with the lid 13 of an electrode 12a among coated electrode 12a, the 12b and be configured to heat the well heater 17 of ion conductor 11.Electrode 12a, 12b are made of porosint, and it is arranged on and is used for applying betwixt electric field on the ion conductor 11.
Therefore, in limit-current type oxygen sensor 10, electrode 12a contacts with inner space 15, and electrode 12b contacts with outside atmosphere.In lid 13 and a side opposed outer surface that be used for being connected, provide well heater 17 so that ion conductor 11 is heated to for example about 400～500 ℃ monitor temperature with ion conductor 11.
As shown in Figure 1, the gas diffusion hole 14 by lid 13 forms in the gas diffuser 16 makes it have certain aperture (S1) and certain axial hole length (l).Form the inner space 15 in the gas diffuser 16, make its gas diffusion hole 14 axially on have certain thickness (lin) (specifically, the distance between the inwall of the surface of electrode 12a and the lid 13 relative) with described surface.In the first embodiment, gas diffuser 16 is configured to make the thickness (lin) of inner space 15 to be equal to or greater than the aperture (S1) of gas diffusion hole 14.Lid 13 can comprise a plurality of gas diffusion holes 14 that are formed at wherein.In this case, the thickness (lin) of the inner space 15 of formation is equal to or greater than all diameter sums of described a plurality of gas diffusion hole 14 or is equal to or greater than by the precalculated value in the effective cross section of described a plurality of gas diffusion holes 14.
Electrode 12a, 12b link to each other with lead 18a, 18b respectively. Lead 18a, 18b are drawn out to the outside, and link to each other to apply monitoring voltage with power supply 30.Power supply 30 is connected with reometer 31, and is in parallel with voltage table 32.In addition, well heater 17 links to each other with lead 19.Lead 19 links to each other with heater power source 33.During use, well heater 17 is powered by heater power source 33 always, and is set in for example about 400 ℃ monitor temperature.
In the limit-current type oxygen sensor 10 of so constructing, heater power source 33 supply electric energy are to well heater 17, and well heater 17 resistance eradiation heats are itself to be heated to monitor temperature with limit-current type oxygen sensor 10.Simultaneously, power supply 30 applies certain monitoring voltage (V) of crossing over electrode 12a, 12b.When applying monitoring voltage, the contained oxygen molecules of gas that exist in the inner space 15 in the gas diffuser 16 that is centered on by ion conductor 11 and lid 13 are accepted electronics by electrode 12a and are become oxonium ion and enter in the ion conductor 11.Oxonium ion moves by the oxygen ion hole in the ion conductor 11, and upwards passes through ion conductor 11 on the thickness direction of the ion conductor shown in Fig. 1 11.The oxonium ion of migration arrives electrode 12b, discharges electronics there and becomes oxygen molecule once more and be discharged in the outside atmosphere.The migration of oxygen molecule causes that the electric current (A) of crossing over electrode 12a and 12b flows.
According to the migration of oxygen molecule, the inner space 15 in the limit-current type oxygen sensor 10 is in negative pressure, and gas flows into wherein from outside atmosphere by gas diffusion hole 14.Be limited in the amount of inflow gas in this case by gas diffusion hole 14.Therefore, in electric current (I)-voltage (V) feature of limit-current type oxygen sensor 10, even when crossing over monitoring voltage that electrode 12a, 12b apply and improve, can this limiting current value of sensing and can not cause the variation of electric current.
Forming limit-current type oxygen sensor 10 makes the thickness (lin) of inner space 15 in the gas diffuser 16 be equal to or greater than the aperture (S1) of gas diffusion hole 14.Therefore, it has the restrictive influence of rate of diffusion in the energy minimization inner space 15 and the restrictive structure of rate of diffusion of pilot-gas diffusion hole 14.
Fig. 4 is the figure that shows voltage (V)-electric current (I) feature in the limit-current type oxygen sensor.As shown in Figure 4, the relation between bias voltage of limit-current type oxygen sensor 10 (Vs) and the output current (Is) has the feature shown in the solid line 41.Just, when the thickness (lin) of inner space 15 in the gas diffuser 16 was equal to or greater than the aperture (S1) of gas diffusion hole 14, the inclination of flat region 42 reached zero or approaching as much as possible zero in the solid line 41.Therefore, in limit-current type oxygen sensor 10, even have external disturbance for example monitoring voltage fluctuation, fluctuating or when changing, output current value in platform area 42 or limiting current value show as constant value.Therefore, can improve the degree of accuracy of sensing limiting current value.The inventor carries out following experiment for the relation between the aperture (S1) of the thickness (lin) of inner space 15 in the gas diffuser 16 and gas diffusion hole 14.
Fig. 5 is presented under the atmosphere of certain oxygen concentration, has the figure of voltage (V)-electric current (I) feature of the limit-current type oxygen sensor of different-thickness inner space in gas diffuser.As shown in Figure 5, solid line 51 is represented when the thickness (lin) of inner space 15 is equal to or greater than the aperture (S1) of gas diffusion hole 14, the feature between bias voltage (Vs) and the output current (Is).Dotted line 52 expression is when the thickness (lin) of inner space 15 during less than the aperture (S1) of gas diffusion hole 14, the feature between bias voltage (Vs) and the output current (Is).Dot-and-dash line 53 expression is when the thickness (lin) of inner space 15 during much smaller than the aperture (S1) of gas diffusion hole 14, the feature between bias voltage (Vs) and the output current (Is).
Therefore, in limit-current type oxygen sensor 10, the thickness (lin) of the inner space 15 of formation is equal to or greater than the aperture (S1) of gas diffusion hole 14, with structure gas diffuser 16.In this case, sensing limiting current value and improve the degree of accuracy of sensing accurately.Like this equally when providing a plurality of this gas diffusion hole 14.In this case, the thickness (lin) of the inner space 15 of formation can be equal to or greater than all diameters (S1) sum of a plurality of gas diffusion holes 14 or be equal to or greater than by the precalculated value in the effective cross section of a plurality of gas diffusion holes 14.
As described above, according to first embodiment of the present invention, the gas diffuser 16 in limit-current type oxygen sensor 10 comprises by lid 13 towards the gas diffusion hole 14 of electrode 12a formation and the inner space 15 that is communicated with gas diffusion hole 14.The thickness (lin) of the inner space 15 that forms is equal to or greater than the aperture (S1) of gas diffusion hole 14.Therefore, the restrictive influence of rate of diffusion in the inner space 15 of its energy minimization limit-current type oxygen sensor 10, and the accurate limiting current value of sensing.
[second embodiment]
Following description relates to according to the limit-current type oxygen sensor of second embodiment of the invention and uses its sensing and the method for measurement oxygen concentration.Limit-current type oxygen sensor according to second embodiment has and the almost similar structure of the sensor of first embodiment, and with reference to describing with the relevant Fig. 1 of first embodiment.As limit-current type oxygen sensor 10 according to first embodiment, limit-current type oxygen sensor according to second embodiment comprises the ion conductor 11 that is made of solid electrolyte, electrode 12a, the 12b of electrode pair are provided with the lid 13 of an electrode 12a among coated electrode 12a, the 12b and are configured to heat the well heater 17 of ion conductor 11.Electrode 12a, 12b are made of porosint, and it is arranged on the ion conductor 11 to apply electric field betwixt.By the cylindrical bottom centre with bottom of lid 13, on the direction of its thickness, form single gas diffusion hole 14.Lid 13 makes gas only can be fed to electrode 12a by gas diffusion hole 14 to be connected to ion conductor 11 with the mode that closely contacts in the face of the side as the electrode 12a of cathode electrode.Face formation inner space 15 between the side of electrode 12a at lid 13 and ion conductor 11.As first embodiment, inner space 15 and gas diffusion hole 14 constitute gas diffuser 16, and it limits rate of diffusion to gas and is provided to electrode 12a.
As shown in Figure 1, the gas diffusion hole 14 by lid 13 forms in the gas diffuser 16 makes it have certain aperture (S1) and certain axial hole length (l).Form inner space 15 in the gas diffuser 16 make its gas diffusion hole 14 axially on have certain thickness (lin) (specifically, the distance between the inwall of the surface of electrode 12a and the lid 13 relative) with described surface.In second embodiment, structure gas diffuser 16 makes the oxygen concentration gradient in the inner space 15 satisfy the condition of the particular expression formula of describing later.Although Gou Zao gas diffuser 16 makes the aperture (S1) of the thickness (lin) of inner space 15 greater than gas diffusion hole 14 here, second embodiment is not limited to this structure.
If the shape of gas diffusion hole 14, the sensor temperature when measuring and atmosphere pressures etc. are constant, the limiting current value of so this limit-current type oxygen sensor 10 depends on the concentration of oxygen in the atmosphere.Therefore, the inventor has analyzed suitable oxygen concentration gradient based on the relation between limiting current value and the oxygen concentration, and is applied to gas diffuser 16.Therefore, make limit-current type oxygen sensor 10 in addition under lower oxygen concentration also sensing and measure oxygen concentration admirably.
Fig. 6 and 7 represents the hole area of gas diffusion hole in the limit-current type oxygen sensor and the relation between hole length and the output current respectively.At first, as mentioned above the inventor in limit-current type oxygen sensor 10 by being formed centrally single gas diffusion hole 14 in lid 13 bottoms.Then in the varying environment that has different hole area (S) and hole length (l) with gas diffusion hole 14, the output current of measuring its extreme current value or sensor (IL).The result confirms can set up between the hole area (S) of gas diffusion hole 14 and ratio (back is called " S/l ") between the hole length (l) and the restriction electric current (IL) relation as shown in Figure 6.In this case, can obtain the represented feature of dotted line 61 and solid line 62.The feature that the theoretical value that is to use regular-expression recited above (1) to calculate that dotted line 61 shows is represented, and solid line 62 demonstrations is the feature of actual measurement value representation.
As shown in Figure 6, find the increase along with S/l value, the limiting current value (IL) that shows based on the solid line 62 of actual measured value is less than the theoretical value of dotted line 61 demonstrations of using regular-expression (1) to calculate.For example, find when the S/l value is in about 50～250 mu m ranges, show linear relationship between S/l value and the restriction electric current (IL).According to this fact hypothesis: for example 1% or lower low oxygen concentration under, not only in the gas diffusion hole 14 of gas diffuser 16 but also in inner space 15, have concentration gradient.Then, analyze approximate equation to calculate the condition of the following expression formula (2) that satisfies the oxygen concentration gradient that is applied to gas diffuser 16.If in about 50～250 mu m ranges the time, also can providing, the S/l value surpasses single gas diffusion hole 14.
At Faraday constant (F), coefficient of diffusion (D), oxygen concentration (C
O2), the hole area (S) of gas diffusion hole, the axial hole length (l) of gas diffusion hole, the thickness (l of inner space
In), the effective cross section (S of inner space
In) and output current value (I
Lim) when having following the relation, the inventor is applied to limit-current type oxygen sensor 10 with oxygen concentration gradient,
[expression formula 2]
Thereby the relation between the inverse (1/IL) of ratio of hole length of the gas diffusion hole that obtains 14 (l) and hole area (S) (back is called " l/S ") and limiting current value is shown in solid line among Fig. 7 71.As a result, for example when S/l recited above is equal to or less than 50 μ m, can the expression formula (1) of routine is applied to gas diffuser 16 with sensing and measurement oxygen concentration, although because limiting current value (IL) is so too little this is unpractiaca.
Output current value (I
Lim) be equal to limiting current value (IL).Set the effective cross section (S of inner space 15 based on following hypothesis
In): oxygen molecule stream spread from gas diffusion hole 14 towards electrode 12a with trapezoidal form in the inner space 15, and half xsect of pact that passes through the xsect of using gases diffusion hole 14 and inner space 15 is as index.
The S/l of the gas diffusion hole 14 of gas diffuser 16 is in the limit-current type oxygen sensor 10 of 150 μ m therein, for example, estimates the feature of monitoring voltage (Vs)-output current (Is) in the oxygen of 1000ppm.In this case, can obtain result shown in solid line among Fig. 8 81,82.Solid line 81 expressions are as the result of regular-expression (1) when being applied to gas diffuser 16.
When the oxygen concentration gradient by above-mentioned expression formula (2) definition is applied to gas diffuser 16 in this mode, the output current value that the output current value that is shown by solid line 82 shows less than solid line 81.When using the oxygen concentration gradient that limits by expression formula (2), can obtain representing the flat region 83 of restriction electric current definitely.As shown in Figure 9, when the oxygen concentration gradient of expression formulas (2) is used in the inner space in the gas diffuser 16 at limit-current type oxygen sensor 10 15, can obtain gas concentration shown in solid line 91 and the linear relationship feature between the output current.
Therefore, for example in addition 1% or lower low oxygen concentration under, can be accurately and sensing and measure the concentration of oxygen admirably according to the limit-current type oxygen sensor 10 of second embodiment of the invention.When the gas diffusion hole in the gas diffuser 16 14 when being single, also can realize easy production in the production stage according to the limit-current type oxygen sensor 10 of second embodiment of the invention, restrain the variation of precision machining feature, and reduce production costs.
As mentioned above, according to second embodiment of the present invention, the gas diffuser 16 of limit-current type oxygen sensor 10 comprises by lid 13 towards the gas diffusion hole 14 of electrode 12a formation and the inner space 15 that is communicated with gas diffusion hole 14.The structure gas diffuser makes the oxygen concentration gradient in inner space 15 satisfy the above-mentioned expression formula (2) as certain condition.In addition, the thickness (lin) of the inner space 15 that for example forms is greater than the aperture (Sl) of gas diffusion hole 14.Therefore, based on the oxygen concentration gradient that satisfies described certain condition, more easily the processing gas diffusion hole 14, and sensing and measure oxygen concentration accurately.This make it can in addition 1% or lower than sensing and measure the concentration of oxygen accurately and admirably under the low oxygen concentration, and be easy to produce, prevent the variation of precision machining feature, and reduce production costs.
Claims (13)
1. limit-current type oxygen sensor comprises:
The ion conductor that constitutes by solid electrolyte;
The porous electrode that comprises first electrode and second electrode is right, and wherein said ion conductor places between described first electrode and second electrode, and described porous electrode applies electric field to being suitable between described first electrode and second electrode;
Be configured to rate of diffusion is limited the gas diffuser that gas is provided to the surface of described first electrode; With
Configuration is used to heat the well heater of described ion conductor;
Wherein said gas diffuser comprises the inner space that contacts with the surface of first electrode and is formed for being communicated with the gas diffusion hole of inner space and gas diffuser space outerpace, wherein said gas diffuser form make first electrode in the described inner space and and its interior surface opposing between distance more than or equal to the aperture of described gas diffusion hole.
2. limit-current type oxygen sensor as claimed in claim 1, wherein said gas diffuser comprises a plurality of gas diffusion holes and the inner space that is communicated with described a plurality of gas diffusion holes, and wherein said gas diffuser forms all diameter sums that the distance that makes in the inner space is equal to or greater than described a plurality of gas diffusion holes.
3. limit-current type oxygen sensor comprises:
The ion conductor that constitutes by solid electrolyte;
The porous electrode that comprises first electrode and second electrode is right, and wherein said ion conductor places between described first electrode and second electrode, and described porous electrode applies electric field to being suitable between described first electrode and second electrode;
Be configured to rate of diffusion is limited the gas diffuser that gas is provided to the surface of described first electrode; With
Configuration is used to heat the well heater of described ion conductor,
Wherein said gas diffuser comprises the inner space that contacts with the surface of first electrode and is formed for being communicated with the gas diffusion hole of described inner space and gas diffuser space outerpace that wherein said gas diffuser is constructed so that the oxygen concentration gradient in the inner space satisfies following expression formula:
1/I
lim＝(1/4FDC
o2){(l/S)+(l
in/S
in)}
Described expression formula is based on Faraday constant (F), coefficient of diffusion (D), oxygen concentration (C
O2), in the axial hole length (l) of the hole area (S) of gas diffusion hole, gas diffusion hole, inner space first electrode and and its interior surface opposing between distance (l
In), the effective cross section (S of inner space
In) and output current value (I
Lim) between relation.
4. limit-current type oxygen sensor as claimed in claim 3, wherein said gas diffuser form make first electrode in the inner space and and its interior surface opposing between distance more than or equal to the aperture of gas diffusion hole.
5. limit-current type oxygen sensor as claimed in claim 3, wherein said gas diffuser are constructed so that the hole area (S) of described gas diffusion hole and the ratio (S/l) of hole length (l) are 50～250 μ m.
6. limit-current type oxygen sensor as claimed in claim 4, wherein said gas diffuser are constructed so that the hole area (S) of described gas diffusion hole and the ratio (S/l) of hole length (l) are 50～250 μ m.
7. an operating limit current oxygen sensors sensing and measure the method for oxygen concentration, described sensor comprises the ion conductor that is made of solid electrolyte, the porous electrode that comprises first electrode and second electrode is right, be configured to be suitable for rate of diffusion is limited the gas diffuser that gas is provided to the surface of described first electrode, with the well heater that is configured to heat described ion conductor, wherein said ion conductor places between described first electrode and second electrode, and described porous electrode applies electric field to being suitable between described first electrode and second electrode, described method comprises:
In gas diffuser, form the inner space that contacts with the surface of described first electrode, and form gas diffusion hole to be communicated with the space outerpace of described inner space and described gas diffuser; With
By calculating the condition that the oxygen concentration gradient that makes in the described inner space satisfies following expression, come sensing and measure the concentration of oxygen:
1/I
lim＝(1/4FDC
o2){(l/S)+(l
in/S
in)}
Described expression formula is based on Faraday constant (F), coefficient of diffusion (D), oxygen concentration (C
O2), in the axial hole length (l) of the hole area (S) of gas diffusion hole, gas diffusion hole, inner space first electrode and and its interior surface opposing between distance (l
In), the effective cross section (S of inner space
In) and output current value (I
Lim) between relation.
8. method as claimed in claim 7, wherein form inner space in the described gas diffuser make win electrode and and its interior surface opposing between distance more than or equal to the aperture of described gas diffusion hole.
9. limit-current type oxygen sensor as claimed in claim 1, in the wherein said inner space first electrode and and its interior surface opposing between distance greater than the aperture of described gas diffusion hole.
10. limit-current type oxygen sensor as claimed in claim 1, wherein said gas diffuser comprises a plurality of gas diffusion holes and the inner space that is communicated with described a plurality of gas diffusion holes, and wherein said gas diffuser forms the distance that makes in the described inner space and is equal to or greater than the value of being calculated by the effective cross section of described a plurality of gas diffusion holes.
11. limit-current type oxygen sensor as claimed in claim 3, wherein said gas diffuser form make first electrode in the described inner space and and its interior surface opposing between distance greater than the aperture of described gas diffusion hole.
12. limit-current type oxygen sensor as claimed in claim 11, wherein said gas diffuser are constructed so that the hole area (S) of described gas diffusion hole and the ratio (S/l) of hole length (l) are 50～250 μ m.
13. method as claimed in claim 7, the inner space in the wherein said gas diffuser form make win electrode and and its interior surface opposing between distance greater than the aperture of described gas diffusion hole.
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| JP2006176883 | 2006-06-27 | ||
| JP2006176882 | 2006-06-27 | ||
| JP2006176882A JP2008008665A (en) | 2006-06-27 | 2006-06-27 | Limiting current type oxygen sensor |
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| CN (1) | CN101097209A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102798655A (en) * | 2012-08-16 | 2012-11-28 | 宁波大学 | Small pore diffusion barrier limiting current type oxygen sensor and its manufacturing method |
| CN103543190A (en) * | 2013-09-18 | 2014-01-29 | 宁波大学 | High-temperature hygrograph and measurement method thereof |
| CN104237338A (en) * | 2014-09-28 | 2014-12-24 | 武汉科技大学 | Method for detecting limited current of oxygen sensor |
| CN110462104A (en) * | 2017-04-10 | 2019-11-15 | 三井金属矿业株式会社 | Solid electrolyte integrated device, the manufacturing method of solid electrolyte integrated device and solid electrolyte device |
| CN111659917A (en) * | 2019-03-06 | 2020-09-15 | 复凌科技（上海）有限公司 | Method for detecting hole on module shell |
| CN114646683A (en) * | 2020-12-18 | 2022-06-21 | 江苏惟哲新材料有限公司 | Ceramic humidity sensor |
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| JPS5272286A (en) * | 1975-12-12 | 1977-06-16 | Toyoda Chuo Kenkyusho Kk | Oxygen concentration analyzer |
| JPS6091251A (en) * | 1983-10-26 | 1985-05-22 | Hitachi Ltd | Air-fuel ratio sensor |
| JPS6093342A (en) * | 1983-10-27 | 1985-05-25 | Toyota Motor Corp | Method for regulating output of element for detecting oxygen concentration |
| JPS62145161A (en) * | 1985-12-19 | 1987-06-29 | Sanyo Electric Co Ltd | Oxygen sensor |
| JPS62263458A (en) * | 1986-05-09 | 1987-11-16 | Matsushita Electric Ind Co Ltd | Oxygen sensor element |
| JPH07111414B2 (en) * | 1989-11-25 | 1995-11-29 | 富士電機株式会社 | Oxygen sensor |
| JPH10185862A (en) * | 1996-12-20 | 1998-07-14 | Fujikura Ltd | Oxygen sensor |
| JP2000131271A (en) * | 1998-10-26 | 2000-05-12 | Hitachi Chem Co Ltd | Limiting current type oxygen sensor |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102798655A (en) * | 2012-08-16 | 2012-11-28 | 宁波大学 | Small pore diffusion barrier limiting current type oxygen sensor and its manufacturing method |
| CN103543190A (en) * | 2013-09-18 | 2014-01-29 | 宁波大学 | High-temperature hygrograph and measurement method thereof |
| CN104237338A (en) * | 2014-09-28 | 2014-12-24 | 武汉科技大学 | Method for detecting limited current of oxygen sensor |
| CN110462104A (en) * | 2017-04-10 | 2019-11-15 | 三井金属矿业株式会社 | Solid electrolyte integrated device, the manufacturing method of solid electrolyte integrated device and solid electrolyte device |
| CN110462104B (en) * | 2017-04-10 | 2021-08-13 | 三井金属矿业株式会社 | Solid electrolyte integrated device, method for manufacturing solid electrolyte integrated device, and solid electrolyte device |
| US11569528B2 (en) | 2017-04-10 | 2023-01-31 | Mitsui Mining & Smelting Co., Ltd. | Solid electrolyte integrated device, method of manufacturing solid electrolyte integrated device, and solid electrolyte element |
| CN111659917A (en) * | 2019-03-06 | 2020-09-15 | 复凌科技（上海）有限公司 | Method for detecting hole on module shell |
| CN114646683A (en) * | 2020-12-18 | 2022-06-21 | 江苏惟哲新材料有限公司 | Ceramic humidity sensor |
| CN114646683B (en) * | 2020-12-18 | 2024-04-23 | 江苏惟哲新材料有限公司 | Ceramic humidity sensor |
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| JP2008008665A (en) | 2008-01-17 |
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