CN106568813A - Method for detecting sulfur components - Google Patents

Abstract

The present invention relates to a method for detecting sulfur components. The content of the sulfur component contained in the fuel is appropriately detected even when the air-fuel ratio of the exhaust gas is changed in the detection of the sulfur component. The sulfur component detection device (1) includes an electrochemical cell (51) including a solid electrolyte layer (11), an electrode (41), and a second electrode (42) having an oxide ion conductivity, a diffusion rate control layer (16) and the measured gas chamber (30). The electrode is arranged in the gas chamber to be measured, and the second electrode is disposed so as to be exposed to the atmosphere. When the content of the sulfur component contained in the fuel is detected, a voltage equal to or higher than the decomposition start voltage of SOx is applied to the electrochemical cell for a predetermined period of time, and then the inter-electrode current is obtained while applying a voltage equal to or higher than the decomposition start voltage of water. Sulfur components are detected based on the current among the electrodes The content of the sulfur component in the second region is lower than the value in the second region when the current between the obtained electrodes is the value in the first region when the sulfur component is detected in the fuel.

Description

Sulfur component detection method

Technical field

The present invention relates to detect the sulfur component detection method of the content of the sulfur composition contained in fuel.

Background technology

In for the fuel of internal combustion engine, it is particularly in Fossil fuel and contains micro sulfur (S) composition.So contain in fuel Some sulfur compositions cause deterioration of the component parts in the gas extraction system of internal combustion engine etc..In addition, if continually suppressed by The control of the deterioration of the component parts that sulfur composition causes, the control that the component parts of deterioration regenerate is made, then cause fuel efficiency Be deteriorated etc..Therefore, in order to variation of fuel efficiency etc. is suppressed in Min., while by the degradation inhibiting of component parts most Little limit, expects the content for correctly detecting the sulfur composition in fuel.

If containing sulfur composition in the fuel used in internal combustion engine, in the waste gas discharged from combustor oxysulfide is contained (SOx).In addition, the content of the sulfur composition in fuel is higher, the SOx concentration contained in waste gas is higher.If it is possible to just Really detect the SOx concentration contained in waste gas, it becomes possible to correctly detect the content of the sulfur composition in fuel.

Therefore, it is proposed to the waste gas sensing detected to the concentration of the oxygen-containing gas composition of the SOx that contains in waste gas etc. Device (referring for example to patent documentation 1).The Abgassensor is useless with being imported into via diffusion rate key-course (law of diffusion speed layer) The tested gas compartment of gas, the first electrochemical cell and the second electrochemical cell.It is electric constituting first in the first electrochemical cell Apply relatively low voltage between the electrode of chemical cell, as a result, the oxygen pump (oxygen for passing through the first electrochemical cell Pumping) act on, the oxygen in tested gas room is removed, and the SOx in tested gas room is not decomposed.On the other hand, Apply higher voltage between the electrode of the second electrochemical cell of composition in two electrochemical cells, thus, by the first electrochemistry Battery except in the waste gas after deoxygenating the SOx that contains be decomposed.Additionally, the oxide ion produced by the decomposition of the SOx passes through The oxygen pump effect of the second electrochemical cell is discharged from tested gas compartment, is flowed with the discharge of the oxide ion by detection Decomposition electric current, detect SOx concentration.

Prior art literature

Patent documentation

Patent documentation 1：Japanese Unexamined Patent Publication 11-190721 publication

The content of the invention

Invent problem to be solved

But, the concentration of the SOx contained in waste gas is very low, therefore, detected by Abgassensor as described above Decompose electric current also very little.Accordingly, it is difficult to correctly detect the decomposition electric current of SOx by Abgassensor as described above.Additionally, Contain water in the offgas, decomposition electric current is also produced by the decomposition of water.In the decomposition electric current produced by the decomposition of water and SOx, It is difficult to only detect the decomposition electric current produced by the decomposition of SOx, is thus also difficult to correctly detect the decomposition electric current of SOx.

In this regard, inventors herein have recognized that, the decomposition of water and SOx is applied in the electrochemical cell acted on oxygen pump Generable voltage is so that the electric current that decomposes when water and SOx decompose changes according to the SOx concentration contained in waste gas.The phenomenon is produced Raw concrete principle is not necessarily clear, but thinks to be produced based on following such mechanism.

That is, if applying decomposition voltage between the electrode of electrochemical cell, the water contained in tested gas and SOx are in electricity It is decomposed on extremely.The decomposition product (for example, sulfur, sulphur compound) for so being produced by the decomposition of SOx adsorbs on electrode, its knot Really, the surface area on the electrode of the decomposition that can aid in water is reduced.If the concentration of the SOx contained in tested gas is high, The decomposition product adsorbed on electrode becomes many, as a result, in electricity when being applied with decomposition voltage between the electrode of electrochemical cell The decomposition electric current of the water of interpolar flowing diminishes.If conversely, the concentration of the SOx contained in tested gas is low, inhaled on electrode Attached decomposition product tails off, as a result, flow between electrode when being applied with decomposition voltage between the electrode of electrochemical cell The decomposition electric current of water becomes big.So, the size of the decomposition electric current of the water for flowing between electrode is according to the SOx contained in tested gas Concentration and change.

Therefore, if using phenomenon as described above, can be based on when decomposition voltage is applied with to electrochemical cell Water decompose electric current to detect waste gas in the SOx concentration that contains.Furthermore it is possible to be based on the concentration of the SOx contained in waste gas to examine Survey the content of the sulfur composition contained in fuel.

But, even if the content of the sulfur composition in fuel is certain, the SOx concentration in waste gas also not necessarily, for example due to The air-fuel ratio of waste gas changes and changes.Therefore, during the decomposition voltage of SOx is applied between the electrode of electrochemical cell, i.e., During the decomposition product for making SOx adsorbs on electrode, if the air-fuel ratio change of waste gas, can not be based on detection SOx concentration precision detects well the content of the sulfur composition in fuel.Therefore, in order to precision detect well sulfur in fuel into The content divided, it is desirable to applying the whole period of the decomposition voltage of SOx to detect SOx concentration, the air-fuel ratio of waste gas is tieed up Hold as certain.But, in the operating of the internal combustion engine of reality, the air-fuel ratio of waste gas is tieed up in a period of being difficult to some extent sometimes Hold as certain.

Therefore, in view of above-mentioned problem, even if it is an object of the present invention to provide in the detection of sulfur composition waste gas air-fuel Than the sulfur component detection method for changing the content that also can suitably detect the sulfur composition contained in fuel.

Means for solving the problems

The present invention is completed to solve above-mentioned problem, and its main points is as described below.

(1) sulfur component detection method, it is the content that the sulfur composition contained in fuel is detected by sulfur component detection apparatus Sulfur component detection method, the sulfur component detection apparatus possess the first electrochemical cell, diffusion rate key-course and tested gas Room, first electrochemical cell possesses the solid electrolyte layer with oxide ion conductive, in the solid electrolyte layer The first electrode configured on one side and the second electrode configured on the another side of above-mentioned solid electrolyte layer, the diffusion speed Rate key-course carries out the diffusion rate control of the tested gas for passing through, and the tested gas compartment is by above-mentioned solid electrolyte layer and above-mentioned Diffusion rate key-course divides to be formed, and above-mentioned first electrode is configured in above-mentioned tested gas room, while electric by above-mentioned second Pole to be exposed to air in the way of configure；The sulfur component detection method includes：Above-mentioned first electrode and above-mentioned second electrode it Between be continuously applied the decomposition of oxysulfide and start first voltage more than voltage until the value of accumulative parameter becomes more than setting Operation, then apply above-mentioned first voltage operation, between above-mentioned first electrode and above-mentioned second electrode apply water point Solution starts second voltage more than voltage, while it is related to obtain the electric current related to the electric electrode current flowed between these electrodes The work of the content of the sulfur composition in the operation of the value of parameter, and the value detection fuel based on the electric current relevant parameter of above-mentioned acquirement Sequence；Above-mentioned accumulative parameter is that the value of the accumulative parameter becomes the integrated flow of oxysulfide more big, in waste gas and becomes more Parameter；It is first area in the value of the electric current relevant parameter of above-mentioned acquirement in the operation of the sulfur composition in above-mentioned detection fuel During interior value, it is judged to that with the value of the parameter of above-mentioned acquirement be in the Zone Full i.e. second area beyond above-mentioned first area Compare during value, the content of the sulfur composition in fuel is low.

(2) the sulfur component detection method described in above-mentioned (1), wherein, the size of above-mentioned first voltage and above-mentioned second voltage It is equal in magnitude.

(3) the sulfur component detection method described in above-mentioned (1) or (2), wherein, above-mentioned electric current relevant parameter is above-mentioned first The electric current flowed between electrode and above-mentioned second electrode, above-mentioned first area is region more than predetermined reference current, And above-mentioned second area is less than the region of above-mentioned predetermined reference current.

(4) the sulfur component detection method described in above-mentioned (1) or (2), wherein, above-mentioned sulfur component detection apparatus are also equipped with second Electrochemical cell, second electrochemical cell possesses the solid electrolyte layer with oxide ion conductive, in solid electricity The 3rd electrode configured on the one side of solution matter layer and the 4th electrode configured on the another side of above-mentioned solid electrolyte layer, By above-mentioned three-electrode configuration in above-mentioned tested gas room, at the same by above-mentioned 4th electrode to be exposed to air in the way of match somebody with somebody Put；Constitute above-mentioned first electrode and above-mentioned 3rd electrode so that between above-mentioned first electrode and above-mentioned second electrode and When being applied with above-mentioned first voltage between above-mentioned 3rd electrode and above-mentioned 4th electrode, the oxysulfide in above-mentioned first electrode Decomposition rate becomes faster than the decomposition rate of the oxysulfide on above-mentioned 3rd electrode；Above-mentioned electric current relevant parameter is above-mentioned Between one electrode and above-mentioned second electrode flow electric electrode current and between above-mentioned 3rd electrode and above-mentioned 4th electrode flow The difference of dynamic electric electrode current, above-mentioned first area is predetermined reference value area below, while above-mentioned second area It is more than the region of above-mentioned predetermined reference value.

Invention effect

According to the present invention, there is provided even if the air-fuel ratio change of waste gas in the detection of sulfur composition also can suitably detect combustion The sulfur component detection method of the content of the sulfur composition contained in material.

Description of the drawings

Fig. 1 is the schematic cross sectional view of the composition for illustrating the sulfur component detection apparatus according to first embodiment.

Fig. 2 is the interelectrode applied voltage for illustrating the first electrochemical cell and the electric electrode current flowed between the electrode Relation figure.

Fig. 3 be electric electrode current when illustrating that applied voltage is 1.0V size and tested gas in the sulfur dioxide that contains Concentration relation figure.

Fig. 4 is to push away the time for illustrating electric electrode current when being continuously applied the applied voltage of 1.1V to the first electrochemical cell The figure of shifting.

Fig. 5 is the flow chart of that illustrates the sulfur composition detection process that ECU is performed.

Fig. 6 is the schematic cross sectional view of the composition for illustrating the sulfur component detection apparatus according to second embodiment.

The explanation of reference

1st, 2 sulfur component detection apparatus

10 element portions

11 first solid electrolyte layers

12 second solid electrolyte layers

16 diffusion rate key-courses

41 first electrodes

42 second electrodes

43 the 3rd electrodes

44 the 4th electrodes

45 the 5th electrodes

46 the 6th electrodes

51 first electrochemical cells

52 second electrochemical cells

53 the 3rd electrochemical cells

60 first circuits

70 tertiary circuits

80 electronic control units (ECU)

90 second circuits

Specific embodiment

Hereinafter, embodiments of the present invention are described in detail referring to the drawings.Should illustrate, in the following description, Identical reference is given to same element.

＜ first embodiments ＞

First, with reference to Fig. 1 to having used the sulfur composition of sulfur component detection apparatus 1 according to the first embodiment of the invention Detection method illustrate.The sulfur component detection apparatus 1 of present embodiment are configured at into the exhaustor (not shown) of internal combustion engine, Carry out the detection (hereinafter also referred to as " detection of sulfur composition ") of the content of sulfur composition in fuel.

Composition ＞ of ＜ sulfur component detection apparatus

As shown in figure 1, possessing the unit with two electrochemical cells according to the sulfur component detection apparatus 1 of first embodiment The tertiary circuit 70 and electricity of first circuit 60 and the connection of another electrochemical cell of part portion 10 and an electrochemical cell connection Sub-control unit (ECU) 80.

As shown in figure 1, element portion 10 constitutes multiple layer stackups, specifically, possess the first solid electrolyte layer 11, Two solid electrolyte layers 12, diffusion rate key-course 16, first are not through layer 21, second are not through layer the 22, the 3rd and are not through layer 23rd, the 4th it is not through layer the 24, the 5th and is not through layer the 25, the 6th being not through layer 26.

Solid electrolyte layer 11,12 is the thin plate with oxide ion conductive.Solid electrolyte layer 11,12 is by example Such as in ZrO₂(zirconium oxide), HfO₂、ThO₂、Bi₂O₃CaO, MgO, Y are assigned with₂O₃、Yb₂O₃Deng the sintered body as stabilizer Formed.In addition, diffusion rate key-course 16 is the thin plate with gas-premeable.Diffusion rate key-course 16 is by for example aoxidizing The porous sintered body of the thermostability inorganic substances such as aluminum, magnesium oxide, Silicon stone matter, spinelle, mullite is formed.It is not through layer 21～26 For the thin plate of gas impermeability, for example, formed as salic layer is wrapped.

Each layer in element portion 10 is not through layer 21, second is not through layer the 22, the 3rd not from the beginning of below Fig. 1 with first Transmission layer 23, the first solid electrolyte layer 11, diffusion rate key-course 16 and the 4th are not through layer 24, the second solid electrolyte layer 12nd, the 5th it is not through the order stacking that layer 25 and the 6th is not through layer 26.

It is impermeable using the first solid electrolyte layer 11, the second solid electrolyte layer 12, diffusion rate key-course 16 and the 4th Cross the division of layer 24 and form tested gas compartment 30.Constitute tested gas compartment 30 so that sulfur component detection apparatus 1 are being configured at into aerofluxuss The waste gas (tested gas) of internal combustion engine is flowed in tested gas compartment 30 via diffusion rate key-course 16 during pipe.That is, by sulfur composition Detection means 1 is configured at exhaustor in the way of diffusion rate key-course 16 is exposed to waste gas, as a result, the Jing of tested gas compartment 30 Connected with exhaust channel by diffusion rate key-course 16.It is explained, as long as tested gas compartment 30 is by the first solid electrolyte The 11, second solid electrolyte layer 12 of layer and diffusion rate key-course 16 are divided and formed, then can be constituted in any form.

In addition, be not through layer 22 and the 3rd using the first solid electrolyte layer 11, second to be not through layer 23 and divide to form the One atmospheric air chamber 31.As shown in Figure 1, the first atmospheric air chamber 31 is configured at into tested gas compartment 30 across the first solid electrolyte layer 11 Opposition side.Make atmosphere opening of first atmospheric air chamber 31 to the outside of exhaustor.Therefore, atmospheric gases flow into the first atmospheric air chamber 31. It is explained, as long as the first atmospheric air chamber 31 is divided by the first solid electrolyte layer 11 being formed, then can constitutes in any form.

Additionally, be not through layer 25 and the 6th using the second solid electrolyte layer 12, the 5th to be not through layer 26 and divide to form the Two atmospheric air chambers 32.As shown in Figure 1, the second atmospheric air chamber 32 is configured at into tested gas compartment 30 across the second solid electrolyte layer 12 Opposition side.Make atmosphere opening of second atmospheric air chamber 32 to the outside of exhaustor.Therefore, atmospheric gases also flow into the second atmospheric air chamber 32.Be explained, as long as the second atmospheric air chamber 32 is divided at least in part by the second solid electrolyte layer 12 being formed, then can with appoint What form is constituted.

Additionally, element portion 10 possesses first electrode 41, second electrode 42, the 5th electrode 45 and the 6th electrode 46.By first Electrode 41 is configured on the surface of the side of tested gas compartment 30 of the first solid electrolyte layer 11.Therefore, expose first electrode 41 Gas in tested gas compartment 30.On the other hand, second electrode 42 is configured in the first big of the first solid electrolyte layer 11 On the surface of the side of air chamber 31.Therefore, the gas (air) that second electrode 42 is exposed in the first atmospheric air chamber 31 is made.By first electrode 41 and second electrode 42 configured with clamping the first solid electrolyte layer 11 and mutually opposing mode.First electrode 41, first is consolidated Body dielectric substrate 11 and second electrode 42 constitute the first electrochemical cell 51.

5th electrode 45 is configured on the surface of the side of tested gas compartment 30 of the second solid electrolyte layer 12.Therefore, make 5th electrode 45 is exposed to the gas in tested gas compartment 30.On the other hand, the 6th electrode 46 is configured at into the second solid electrolytic On the surface of the side of the second atmospheric air chamber 32 of matter layer 12.Therefore, the gas for making the 6th electrode 46 be exposed in the second atmospheric air chamber 32 is (big Gas).5th electrode 45 is configured with the 6th electrode 46 with clamping the second solid electrolyte layer 12 and mutually opposing mode.5th Electrode 45, the second solid electrolyte layer 12 and the 6th electrode 46 constitute the 3rd electrochemical cell 53.

5th electrode 45 is more closely configured at into diffusion rate control in tested gas compartment 30 compared with first electrode 41 16 side of layer.Therefore, via diffusion rate key-course 16 tested gas in tested gas compartment 30 is flowed into first in the 5th electrode 45 Surrounding circulates, and then, circulates around first electrode 41.

In the present embodiment, the material of first electrode 41 is constituted comprising the platinum families such as platinum (Pt), rhodium (Rh) and palladium (Pd) unit Element or their alloy are used as main component.Preferably, first electrode 41 be comprising in platinum (Pt), rhodium (Rh) and palladium (Pd) extremely Porous cermet electrode of few one as main component.But, the material for constituting first electrode 41 is not necessarily limited to above-mentioned material Material, as long as can will be tested in tested gas compartment 30 when applying the voltage for specifying between first electrode 41 and second electrode 42 The water contained in gas and SOx reduction decompositions, it is possible to be any material.

In addition, in the present embodiment, second electrode 42 is the porous metalloceramic comprising platinum (Pt) as main component Electrode.But, the material for constituting second electrode 42 is not necessarily limited to above-mentioned material, as long as first electrode 41 and second electrode 42 it Between apply specify voltage when oxide ion can be made to move between first electrode 41 and second electrode 42, it is possible to be appoint What material.

On the other hand, the 5th electrode 45 and the 6th electrode 46 are the porous metalloceramic comprising platinum (Pt) as main component Electrode.But, the material for constituting the 5th electrode 45 is not necessarily limited to above-mentioned material, as long as the 5th electrode 45 and the 6th electrode 46 it Between apply the hydrogen reduction contained in the tested gas in tested gas compartment 30 can be decomposed during the voltage for specifying, it is possible to be times What material.Additionally, the material for constituting the 6th electrode 46 nor be it necessarily limited to above-mentioned material, as long as in the 5th electrode 45 and the 6th electrode Apply during the voltage for specifying oxide ion can be made to move between the 5th electrode 45 and the 6th electrode 46 between 46, it is possible to It is any material.

It is explained, in the above-described embodiment, the 3rd electrochemical cell 53 is included and constitutes the first electrochemical cell 51 Different the second solid electrolyte layer 12 of the first solid electrolyte layer 11 and constitute.But, the first solid electrolyte layer and Two solid electrolyte layers can be same solid electrolyte layer.That is, first solid electrolyte layer 11 of Fig. 1 can be solid as second Body dielectric substrate function, thus the 3rd electrochemical cell 53 can comprising the first solid electrolyte layer 11 and constitute.At this In the case of, the 6th electrode 46 is configured on the surface of the side of the first atmospheric air chamber 31 of the first solid electrolyte layer 11, it is electric by the 5th Pole 45 is configured on the surface of the side of tested gas compartment 30 of the first solid electrolyte layer 11.

Further, element portion 10 possesses heater (electric heater) 55.In the present embodiment, as shown in figure 1, by heater 55 are configured in first is not through layer 21 and second and is not through between layer 22.Heater 55 is for example, comprising platinum (Pt) and ceramic (example Such as aluminium oxide) ceramic-metallic thin plate, for the heater generated heat by energization.Heater 55 can be electrochemical by first Learn the electrochemical cell 53 of battery 51 and the 3rd to be heated to more than active temperature.

As shown in figure 1, the first circuit 60 possesses the first power supply 61 and the first galvanometer 62.First power supply 61 and first is electric Flowmeter 62 is connected to electronic control unit (ECU) 80.First power supply 61 becomes to be above first electrode with the current potential of second electrode 42 The mode of 41 current potential applied voltage between first electrode 41 and second electrode 42.The voltage applied by the first power supply 61 it is big It is little by ECU80 controls.

On the other hand, the first galvanometer 62 detects the electric current flowed between first electrode 41 and second electrode 42 (also Be, the electric current of flowing in the first solid electrolyte layer 11) i.e. the size of electricity electrode current.Obtained using the first galvanometer 62 The detected value of electric electrode current is transfused to ECU80.

In addition, as shown in figure 1, tertiary circuit 70 possesses the 3rd power supply 71 and the 3rd galvanometer 72.By the He of the 3rd power supply 71 3rd galvanometer 72 is connected to ECU80.3rd power supply 71 becomes to be above the current potential of the 5th electrode 45 with the current potential of the 6th electrode 46 Mode between the 5th electrode 45 and the 6th electrode 46 applied voltage.The size of the voltage applied by the 3rd power supply 71 by ECU80 is controlled.

On the other hand, the 3rd galvanometer 72 detects the electric current flowed between the 5th electrode 45 and the 6th electrode 46 (also Be, the electric current of flowing in the second solid electrolyte layer 12) i.e. the size of electricity electrode current.Obtained using the 3rd galvanometer 72 The detected value of electric electrode current is transfused to ECU80.

ECU80 is the ROM and interim storage data for possessing the program that CPU, the storage CPU for performing operation is performed etc. The digital computer of RAM etc..ECU is connected to into the various executive components (Fuelinjection nozzle, choke valve etc.) of internal combustion engine, this is controlled The action of a little executive components.

ECU80 can be controlled by the first power supply 61 in first electrode 41 and second electrode 42 by controlling the first power supply 61 Between apply the first applied voltage.In addition, ECU80 can be controlled by the 3rd power supply 71 the by controlling the 3rd power supply 71 The second applied voltage applied between five electrodes 45 and the 6th electrode 46.Therefore, ECU80, the first power supply 61 and the 3rd power supply 71 As can apply between electrode between first electrode 41 and second electrode 42 and between the 5th electrode 45 and the 6th electrode 46 Voltage simultaneously controls the voltage bringing device function of these inter-electrode voltages.

In addition, flowing between first electrode 41 and second electrode 42 to ECU80 inputs and by what the first galvanometer 62 was detected The corresponding signal of size of dynamic electric electrode current.Therefore, ECU80 and the first galvanometer 62 as detection in the He of first electrode 41 The test section function of the electric electrode current flowed between second electrode 42.Additionally, being input into and being detected by the 3rd galvanometer 72 The electrode current flowed between the 5th electrode 45 and the 6th electrode 46 the corresponding signal of size.Therefore, ECU80 and the 3rd The test section function of the electric electrode current that galvanometer 72 flows as detection between the 5th electrode 45 and the 6th electrode 46.

＜ basic sulfur composition detection principle ＞

Then, the Cleaning Principle of the SOx using the sulfur component detection apparatus according to present embodiment is illustrated.

When the Cleaning Principle to SOx is illustrated, first, the pole to the oxygen in the element portion 10 that constitutes as described above Properties of flow of rationing the power supply is illustrated.In the element portion 10 for constituting as described above, if the electrode of the side of tested gas compartment 30 made For negative electrode, using the electrode of atmospheric gases room side as anode and between these electrodes applied voltage, then contain in tested gas Oxygen is reduced decomposition and becomes oxide ion.The oxide ion via electrochemical cell 51,53 solid electrolyte layer 11, 12 and be transmitted to anode-side and become oxygen, in being discharged to air.Hereinafter, by such Jing from from cathode side to anode-side The movement of the oxygen produced by the conduction of the oxide ion of solid electrolyte layer is referred to as " oxygen pump effect ".

By the conduction of the oxide ion with the effect of such oxygen pump, electric electrode current is constituting electrochemical cell 51st, flow between 53 electrode.Become higher in the applied voltage for constituting applying between the electrode of each electrochemical cell 51,53, the electricity Electrode current becomes bigger.This is that, because applied voltage becomes higher, the conductive quantity of oxide ion just becomes more.

But, if making applied voltage raise at leisure and becoming more than certain certain value, electric electrode current will not become It is maintained at certain value greatly again.Such characteristic is referred to as into the carrying current characteristic of oxygen, the carrying current for producing oxygen is special The voltage regime of property is referred to as the carrying current region of oxygen.The carrying current characteristic of such oxygen is generated as follows：As voltage is applied Plus and the conduction velocity of the oxide ion of conduction can exceed via diffusion rate key-course 16 in solid electrolyte layer 11,12 And the boot speed of the oxygen being imported in tested gas compartment 30.That is, because the reduction decomposition of the oxygen on negative electrode is reacted to diffusion Rate control state and produce.

Therefore, between the electrode in the voltage being applied with the carrying current region of oxygen above-mentioned electrochemical cell 51,53 Concentration of the electric current (carrying current) corresponding to the oxygen contained in tested gas.By so using the carrying current characteristic of oxygen, energy Enough detect the concentration of the oxygen contained in tested gas, and the air-fuel ratio based on the Concentration Testing waste gas.

But, above-mentioned such oxygen pump effect is not the effect manifested in the oxygen for only containing in tested gas.In molecule In the gas that can manifest oxygen pump effect is there is also in the gas containing oxygen atom.As such gas, SOx and water can be enumerated (H₂O).Therefore, by apply between the first electrode 41 and second electrode 42 of the first electrochemical cell 51 SOx and water point Solution starts voltage more than voltage, and the water and SOx contained in tested gas is decomposed.The oxidation produced by the decomposition of SOx and water Thing ion is acted on by oxygen pump, and from first electrode 41 second electrode 42 is transmitted to, and is accompanied with it, and electric electrode current is in these electricity Interpolar flows.

But, the concentration of the SOx contained in waste gas is very low, and the electric electrode current produced because of the decomposition of SOx is also very It is little.Especially, in the offgas electric electrode current is produced because of the decomposition of water containing substantial amounts of water.Accordingly, it is difficult to precision is well Distinguish and detect the electric electrode current produced because of the decomposition of SOx.

On the other hand, if applying SOx's between the first electrode 41 and second electrode 42 of the first electrochemical cell 51 Decompose the first voltage for starting regulation more than voltage, then as described above, the SOx contained in tested gas is decomposed.Its knot Really, the decomposition product (such as sulfur and sulphur compound) of SOx adsorbs in the first electrode 41 as negative electrode.If such Absorption quantitative change of the decomposition product of SOx in first electrode 41 is more, then it is assumed that correspondingly the surface of first electrode 41 is decomposed Product is covered, and is accompanied with it, and the area that can aid in the first electrode 41 of the decomposition of water reduces.Therefore, if so In the state of the area reduction of the first electrode 41 that can aid in the decomposition of water, between first electrode 41 and second electrode 42 The decomposition for applying water starts the second voltage of regulation more than voltage, the then electric electrode current for flowing between these electrodes 41,42 Reduce.That is, the SOx concentration contained in tested gas becomes higher, in the absorption of the decomposition product on the surface of first electrode 41 Amount becomes more, as a result, the electric electrode current when decomposition for being applied with water starts second voltage more than voltage reduces.Cause This, can based on be applied with water decomposition start voltage more than second voltage when electric electrode current to detect tested gas in The concentration of the SOx for containing.

Here, the decomposition of water starts the decomposition of voltage and SOx, and to start voltage different because of condition determination etc., condition determination and Decomposing the relation of beginning voltage not necessarily can illustrate.But, although the decomposition that water can be observed starts voltage because of condition determination Deng and change, but for about 0.6V～about 0.8V.Additionally, it is same degree that the decomposition of SOx start voltage to start voltage with the decomposition of water, Or it is more lower slightly than its.Decomposition accordingly, as water starts voltage of the second voltage more than voltage for 0.6V～more than 0.8V.Together Sample ground, the first voltage that the decomposition as SOx starts more than voltage is also the voltage of 0.6V～more than 08V.It is explained, first Voltage can also be set to voltage more than the decomposition beginning voltage of water.In addition, first voltage can be equal with second voltage Voltage.

On the other hand, if making the applied voltage between first electrode 41 and second electrode 42 rise from 0.6V, with it Concomitantly, the decomposition rate increase of the water in first electrode 41.Therefore, along with the rising of applied voltage, in first electrode 41 The electric electrode current flowed and second electrode 42 between also increases.But, if between first electrode 41 and second electrode 42 Applied voltage becomes the voltage more than lower voltage limit in the carrying current region of water, then in first electrode 41 decomposable water point Solution speed exceedes the boot speed of the water being imported into via diffusion rate key-course 16 in tested gas compartment 30.That is, the limit of water Current characteristics manifests.In this case, between first electrode 41 and second electrode 42 flow electric electrode current according to The concentration of water and change, it is difficult to detect the SOx concentration contained in tested gas well based on current precision between electrode.In addition, In the case where applied voltage is too high, it is possible to cause the decomposition of the first solid electrolyte layer 11, in this case, it is also difficult to base Current precision detects well the concentration of the SOx contained in tested gas between electrode.

Therefore, in the present embodiment, even if starting electricity in the decomposition for applying above-mentioned water to the first electrochemical cell 51 When the decomposition of pressure or SOx starts voltage more than voltage, also the voltage is set to ration the power supply under the carrying current region less than water The voltage of pressure.Although the lower voltage limit that the carrying current region of water can be observed slightly has and change because of condition determination etc., it is for about 2.0V.Therefore, in the present embodiment, above-mentioned first voltage and second voltage are all the voltage less than 2.0V.

Applied voltage is specifically explained with the relation of electric electrode current.Fig. 2 is illustrated in the first electrochemical cell The schematic diagram of the relation of applied voltage and electric electrode current when making applied voltage slowly increase (boost and scan) in 51.In diagram Example in, used the SO contained in tested gas₂The concentration of (i.e. SOx) it is different 4 kinds (0ppm, 100ppm, 300ppm and 500ppm) tested gas.Additionally, contain in the tested gas of the first electrode (negative electrode) 41 of the first electrochemical cell 51 of arrival The concentration of oxygen by being configured at the 3rd electrochemical cell 53 of the upstream side of the first electrochemical cell 51, in all tested gases All it is maintained certain (substantially 0ppm).

First, solid line L1 represents the SO contained in tested gas₂Concentration be 0ppm when applied voltage and electrode between electricity The relation of stream.As shown in Figure 2, it is less than about in the region of 0.6V in applied voltage, electric electrode current substantially 0.This is due to such as Aftermentioned, the oxygen contained in the tested gas in tested gas compartment 30 is removed by the 3rd electrochemical cell 53.On the other hand, such as Into for about more than 0.6V, then along with the increase of applied voltage, electric electrode current starts increase to fruit applied voltage.Electricity between the electrode The increase of stream is attributed to the decomposition for having started the water in first electrode 41.

Secondly, dotted line L2 represents the SO contained in tested gas₂Concentration be 100ppm when applied voltage and electrode between The relation of electric current.In this case, it is less than about in the region of 0.6V in applied voltage, it is same with the situation of solid line L1, between electrode Electric current also substantially 0.On the other hand, when applied voltage is for about more than 0.6V, electric electrode current flows because of the decomposition of water.But That compared with solid line L1, now the electric electrode current of (dotted line L2) is little, in addition, compared with solid line L1, electric electrode current relative to The increment rate (slope in Fig. 2) of applied voltage is also little.

Further, chain-dotted line L3 and double dot dash line L4 represent the SO contained in tested gas₂Concentration be 300ppm and The relation of applied voltage and electric electrode current during 500ppm.In these cases, the region of 0.6V is less than about in applied voltage In, electric electrode current also substantially 0 same with the situation of solid line L1 and dotted line L2.On the other hand, it is for about 0.6V in applied voltage During the above, electric electrode current flows because of the decomposition of water.But, the SO contained in tested gas₂Concentration it is higher, between electrode electricity Stream is less, in addition, the SO contained in tested gas₂Concentration it is higher, electric electrode current relative to applied voltage increment rate (figure Slope in 2) it is also less.

So, example as shown in Figure 2 will also realize that, applied voltage be SOx and the decomposition of water start voltage i.e. about 0.6V with The size of electric electrode current when upper is according to the SO contained in tested gas₂The concentration of (i.e. SOx) and change.For example, if phase For the SO contained in tested gas₂Concentration draw line L1 when applied voltage in the coordinate diagram shown in Fig. 2 is 1.0V The size of the electrode current in～L4, then obtained the coordinate diagram shown in Fig. 3.

From the figure 3, it may be seen that electric electrode current when being applied with the voltage of regulation (being 1.0V in the example shown in Fig. 3) is big It is little according to the SO contained in tested gas₂The concentration of (i.e. SOx) and change.Therefore, as described above, can be based on and be applied with water Electric electrode current when starting assigned voltage more than voltage with the decomposition of SOx is detecting the concentration of SOx.

<Problem points>

But, if for containing sulfur composition in the fuel of internal combustion engine, in the waste gas discharged from the combustor of internal combustion engine Containing SOx.And, the content of the sulfur composition in fuel is higher, and the concentration of the SOx contained in waste gas is also higher.Therefore, as described above Like that, by detecting the concentration of SOx based on electric electrode current using sulfur component detection apparatus 1, fuel can substantially be detected In sulfur composition content.

But, if detecting the concentration of SOx by method as described above, the concentration of SOx is not only because of the sulfur in fuel The content of composition and change, and change because of the air-fuel ratio of waste gas.Especially, in the air-fuel ratio and chemically correct fuel of waste gas In the case of being in a ratio of dilute air-fuel ratio, the degree of " dilute " of the air-fuel ratio of waste gas becomes higher (air-fuel ratio becomes bigger), then fire Expect to become lower to the ratio of air.Therefore, in this case, even if the content of the sulfur composition contained in fuel is certain, It is that the degree of " dilute " of the air-fuel ratio of waste gas becomes higher, then the SOx concentration in waste gas becomes lower.

Therefore, detect the content of the sulfur composition in fuel well for precision, need using sulfur component detection apparatus 1 SOx whole detection during the air-fuel ratio of waste gas is maintained into certain.That is, in sulfur component detection apparatus 1, need to the One electrochemical cell 51 be applied with first voltage it is whole during the air-fuel ratio of waste gas is maintained into certain.But, even if assuming The control of fuel injection amount etc. is carried out so that the air-fuel ratio of waste gas is maintained into certain mode, in internal combustion engine, along with starting The change of machine load, engine revolution, the air-fuel ratio of waste gas also can change.Therefore, in the operating of actual internal combustion engine, it is difficult to The air-fuel ratio of waste gas is maintained into certain in the whole period of certain degree.Accordingly, it is difficult to the sulfur in high precision test fuel into The content divided.

The Cleaning Principle ＞ of ＜ sulfur compositions

But, the concentration of the SOx contained in the concentration of the SOx for containing in the offgas, i.e. tested gas be, for example, 0ppm～ In the case of number ppm or so, even if the decomposition that SOx is chronically continuously applied to the first electrochemical cell 51 starts more than voltage The first voltage of regulation, the decomposition product of SOx also hardly adsorbs in first electrode 41.If as a result, to first Electrochemical cell 51 is chronically continuously applied after first voltage, to the first electrochemical cell 51 apply water decomposition start voltage with On second voltage carry out electric current between detecting electrode, then electric electrode current becomes larger value.

On the other hand, the concentration of the SOx for containing in the offgas be it is more than the concentration of certain degree in the case of, if to first Electrochemical cell 51 is chronically continuously applied first voltage, as a result first electrode 41 will be decomposed product covering.As a result, If after chronically first voltage is continuously applied to the first electrochemical cell 51, applying second to the first electrochemical cell 51 electric Press to detect the electric electrode current of the first electrochemical cell 51, then electric electrode current becomes less value.

Fig. 4 is the time for illustrating the electric electrode current when applied voltage of 1.1V is continuously applied to the first electrochemical cell 51 The figure of passage.Same with Fig. 2, solid line L1, dotted line L2 and chain-dotted line L3 represent respectively the SO contained in tested gas₂Concentration be The time passage of electric electrode current when 0ppm, 100ppm and 300ppm.In the example shown in Figure 4, in moment t₁Made in the past Applied voltage is less than 0.6V, and in moment t₁After, make applied voltage become 1.1V.

As shown in figure 4, the SO contained in tested gas₂Concentration be 0ppm in the case of (solid line L1), i.e. in fuel In sulfur composition content be 0 in the case of, if in moment t₁Voltage (the SOx of 1.1V is applied to the first electrochemical cell 51 Decomposition start more than voltage and the decomposition of water starts more than voltage), then the electric electrode current urgency in the first electrochemical cell 51 Increase severely big.This is due in moment t₁Later in the decomposition of the enterprising water-filling of first electrode 41.Thereafter, electric electrode current hardly subtracts It is little and converge certain value.This is because the decomposition product of SOx does not adsorb in first electrode 41.

The SO contained in tested gas₂Concentration be 100ppm in the case of (dotted line L2), the sulfur i.e. in fuel into In the case that the content divided is moderate, if in moment t₁The voltage of 1.1V is applied to the first electrochemical cell 51, then the Electric electrode current in one electrochemical cell 51 is increased dramatically.Thereafter, because the decomposition product of SOx adsorbs in first electrode 41 On, therefore electric electrode current slowly reduces, and finally converges certain value.Value of the value for now restraining less than solid line L1 convergences. This is that the decomposition product of the SOx due to adsorbing is covered in first electrode 41, finally can not be adsorbed again in first electrode 41 Decomposition product (adsorption saturation of the decomposition product in first electrode 41).

The SO contained in tested gas₂Concentration be 300ppm in the case of (chain-dotted line L3), the sulfur i.e. in fuel In the case of the content height of composition, if in moment t₁The voltage of 1.1V is applied to the first electrochemical cell 51, then first is electrochemical The electric electrode current learned in battery 51 is increased dramatically.Thereafter, because the decomposition product absorption of SOx is in first electrode 41, because This electric electrode current slowly reduces, and finally converges certain value.In this case, the SO for containing in tested gas₂Concentration Height, therefore adsorption rate of the decomposition product in first electrode 41 is fast, the thus reduction of the electric electrode current in chain-dotted line L3 Speed is faster than the reduction speed of the electric electrode current in dotted line L2.In addition, the value that the value of chain-dotted line L3 convergences restrains with dotted line L2 It is equal.Even if this is the SO due to containing in tested gas₂Concentration be 300ppm in the case of, be also with its concentration The situation of 100ppm is same, and the decomposition product of SOx is covered in first electrode 41, and final decomposition product is in first electrode 41 On adsorption saturation.

Even if the air-fuel ratio change of such tendency waste gas is also not substantially changed.The content of the sulfur composition in fuel is non- In the case of often low, if the decomposition that SOx is chronically continuously applied to the first electrochemical cell 51 starts regulation more than voltage First voltage, even if then changing in the air-fuel ratio of during this period waste gas, the decomposition product of SOx also hardly adsorbs electric first On pole 41.As a result, in this case, even if the air-fuel ratio of waste gas changes in the applying of first voltage, water is applied with thereafter Decomposition start voltage more than second voltage when electric electrode current also converge to the value same with the solid line L1 of Fig. 4.

On the other hand, in the case that the content of the sulfur composition in fuel is more than moderate, if electrochemical to first Learn battery 51 and be chronically continuously applied first voltage, even if then changing in the air-fuel ratio of waste gas during this period, the decomposition product of SOx Still adsorb in large quantities in first electrode 41.As a result, finally, adsorption saturation of the decomposition product in first electrode 41. Therefore, in this case, even if the air-fuel ratio of waste gas changes in the applying of first voltage, when being applied with second voltage thereafter Electric electrode current also converges to the value same with the dotted line L2 of Fig. 4 and chain-dotted line L3.

＜ sulfur composition detection processes ＞

Therefore, in the present embodiment, the detection process of sulfur composition are carried out by following such order.First, exist Apply SOx between the first electrode 41 and second electrode 42 of the first electrochemical cell 51 decompose more than beginning voltage first is electric Pressure (the moment t of Fig. 4₁).Then, it is continuously applied first between two electrodes 41,42 during the persistent period △ t of regulation electric Pressure.Thus, if the content of the sulfur composition in fuel is for more than moderate, the decomposition product of SOx in a large number absorption the On one electrode 41.On the other hand, if the content of the sulfur composition in fuel is very low, the decomposition product of SOx does not almost have Absorption is in first electrode 41.

Then, in (the moment t from the beginning of the applying of first voltage₁) elapsed time become the persistent period △ t of regulation Moment t above₂, between the first electrode 41 and second electrode 42 of the first electrochemical cell 51 apply water decomposition start electricity The second voltage of the pressure above.Now, if the content of the sulfur composition in fuel is few, the decomposition product of SOx is in first electrode Adsorbance on 41 is few, therefore electric electrode current when being applied with second voltage becomes predetermined more than reference current It. Therefore, in the case that the electric electrode current when second voltage is applied with is predetermined more than reference current It, it is judged to The content of the sulfur composition in fuel is below the reference level of regulation.

If conversely, the content of the sulfur composition in fuel is high, electric electrode current when being applied with second voltage becomes and is less than Predetermined reference current It.Therefore, the electric electrode current when second voltage is applied with is less than predetermined benchmark electricity In the case of stream It, the content of the sulfur composition being judged in fuel is more than reference level.

Here, the galvanic areas of more than reference current It are set to into first area, by the Current Zone less than reference current It Domain is set to second area.Therefore, second area can be referred to as the whole galvanic areas beyond first area.In this embodiment party In formula, when the electric electrode current when second voltage is applied with to the first electrochemical cell 51 is the value in first area, judge On the basis of the content of the sulfur composition in fuel below content.On the other hand, to be applied with second to the first electrochemical cell 51 electric When electric electrode current during pressure is the value in second area, the content for judging the sulfur composition in fuel is higher than reference level.Therefore, In the present embodiment, the size of the electric electrode current when second voltage is applied be first area in value when, judge with For value in second area when compare, the content of the sulfur composition in fuel is low.

It is unrelated with the air-fuel ratio of waste gas by the content of the sulfur composition in so detection fuel, can detect in fuel Whether the content of sulfur composition is less than reference level.Especially, the content of sulfur composition in fuel can be distinguished for it is considerably less when with When the content of the sulfur composition in fuel is more than moderate.

Here, as described above, first voltage is preferably set to the voltage equal with second voltage.In this case, will be from Moment t₁To moment t₂Applied voltage and moment t₂Later applied voltage is set to equal voltage.So, by electric by first Pressure is set to equal voltage with second voltage, it is not necessary in moment t₂The switching of voltage is carried out, therefore, it is possible to make applied voltage Control is simple.In addition, when SOx and water is decomposed, applying than disassembling beginning voltage (0.6V～0.8V) height voltage to a certain degree The decomposition of SOx and water can be promoted.Thus, for example, first voltage and second voltage are 1.1V.

But, first voltage and second voltage are not necessarily required to as equal voltage.Therefore, second voltage can be higher than the One voltage.Start voltage less than the decomposition of water because the decomposition for thinking SOx as described above starts voltage, therefore, it is possible to be used for The first voltage for decomposing SOx and applying is set to relatively low voltage.As a result, the electricity associated with the detection of sulfur composition can be suppressed Power is consumed, and can suppress the variation of fuel efficiency.Conversely, first voltage can also be higher than second voltage.In this case, can Promote the decomposition of SOx in the applying of first voltage.

It is explained, in the above-described embodiment, in the first electrochemical cell 51 during the persistent period △ t of regulation Electrode between apply first voltage.Persistent period △ t are set as into the time as following：Sulfur composition in fuel contains When measuring as more than setting, if applying first voltage to the first electrochemical cell 51 during persistent period △ t, divide Adsorption saturation of the solution product in first electrode 41.Therefore, in other words, persistent period △ t is set as follows：In combustion When the content of the sulfur composition in material is more than setting, the SOx during persistent period △ t in the waste gas of exhaust circulation pipe Integrated flow become a certain amount of.

In addition, in the above-described embodiment, in the electricity of the first electrochemical cell 51 during the persistent period △ t of regulation Interpolar applies first voltage.But, with regard between the electrode in the first electrochemical cell 51 apply first voltage during for, if Value for parameter becomes the integrated flow of the SOx in bigger, waste gas and just becomes more such parameters (hereinafter referred to as " accumulative ginseng Number "), then can be based on the other parameters beyond the time and determine.Accordingly, as such accumulative parameter, in addition to " time ", It is contemplated that " being inhaled into the aggregate-value of the inhaled air volume of the combustor of internal combustion engine ", " Fuelinjection nozzle from internal combustion engine is to burning Aggregate-value of the fuel feed of room supply " etc..

And, in the detection process of sulfur composition, between the electrode of the first electrochemical cell 51 apply first voltage until The value of accumulative parameter becomes more than setting.Setting now is set as into value as following：When the sulfur composition in fuel Content when being more than setting, if first voltage is being continuously applied to the first electrochemical cell 51 until the value of accumulative parameter Become the setting, then adsorption saturation of the decomposition product in first electrode 41.

＜ pump units ＞

In first electrochemical cell 51, as described above, between first electrode 41 and second electrode 42, apply SOx point Thus solution starts first voltage more than voltage decomposes the SOx in first electrode 41, while being started by applying the decomposition of water Second voltage more than voltage, the detection electric electrode current associated with the decomposition of the water in first electrode 41.But, reach Containing in the case of aerobic in the tested gas of the first electrochemical cell 51, there is the decomposition (ion of oxygen in first electrode 41 Change), while resulting oxide ion is flowed to second electrode 42 from first electrode 41.So, if the decomposition phase with oxygen With electric current flowing is decomposed between first electrode 41 and second electrode 42, then can not correctly detect SOx's based on electric electrode current Concentration.

Here, as described above, if applying the voltage in the carrying current region of oxygen to the 3rd electrochemical cell 53, The conduction velocity of the oxide ion for applying to be conducted by the 3rd electrochemical cell 53 along with voltage is become faster than via expansion Scattered rate control layer 16 and the boot speed of oxygen that is imported in tested gas compartment 30.Therefore, if by the carrying current area of oxygen Voltage in domain puts on the 3rd electrochemical cell 53, then can will flow into tested gas compartment 30 via diffusion rate key-course 16 The oxygen almost all contained in interior tested gas is removed.

Therefore, in the present embodiment, following operation is taken：Pair more closely configure compared with the first electrochemical cell 51 The 3rd electrochemical cell 53 in the side of diffusion rate key-course 16 applies the voltage in the carrying current region of oxygen.The limit electricity of oxygen Even if stream region is applied voltage is risen to more than it, the lower voltage limit (such as 0.1V) that electric electrode current also hardly changes Region above.Additionally, the decomposition being set to the applied voltage of the 3rd electrochemical cell 53 less than SOx and water is started into voltage The voltage of (about 0.6V).If so applied voltage of the setting to the 3rd electrochemical cell 53, will can contain in tested gas Some oxygen solutions, are removed via the second solid electrolyte layer 12.Further, since the applying electricity to the 3rd electrochemical cell 53 Pressure starts voltage less than the decomposition of SOx and water, therefore on the 5th electrode 45 of the 3rd electrochemical cell 53, do not occur water and The decomposition of SOx.Therefore, the 3rd electrochemical cell 53 is not discharged in water and SOx as discharging oxygen from tested gas compartment 30 Pump unit function.

<Concrete control>

The concrete control for carrying out the detection process of above-mentioned sulfur composition is illustrated with reference to Fig. 5.Fig. 5 is to illustrate ECU80 The flow chart of of the detection process of the sulfur composition of execution.It is explained, in the present embodiment, to the 3rd electrochemical cell 53 applied voltage is for example typically set to 0.4V.

First, as shown in step sil, ECU80 judges whether the testing conditions of sulfur composition are set up.Specifically, (or open after ignition switch or by last time fuel filler after), the detection process of sulfur composition are complete after the startup of such as internal combustion engine Into in the case of, being judged to the testing conditions of sulfur composition is false.That is, as long as the content of the sulfur composition in fuel does not carry out fuel Oil supply just do not change.Therefore, if once the detection of sulfur composition is completed, avoid the need for so continually carrying out the inspection of sulfur composition Survey is processed.Therefore, in the case that the detection process in sulfur composition are completed, being judged to the testing conditions of sulfur composition is false.

In step s 11, in the case of being judged to that SOx testing conditions are invalid, into step S12.In step S12 In, ECU80 makes to become 0.30V to the applied voltage of the first electrochemical cell 51.So, if made to the first electrochemical cell 51 Applied voltage be that less than 0.45V, then oxide ion is moved via the solid electrolyte layer 11 of the first electrochemical cell 51, is made Become the slightly superfluous state of oxygen in the first electrode 41 for obtaining the first electrochemical cell 51.As a result, in the decomposition product of SOx In the case of adsorbing in first electrode 41, depart from decomposition product.

On the other hand, in step s 11, in the case where the testing conditions for being judged to sulfur composition are set up, into step S13.In step s 13, ECU80 makes to become the applied voltage of the first electrochemical cell 51 1.1V (first voltage).Therefore, root According to the SOx concentration contained in tested gas, the decomposition product of SOx adsorbs at leisure in first electrode 41.

Then, in step S14, ECU80 judges to make the applied voltage to the first electrochemical cell 51 as the Jing after 1.1V Cross whether the time is more than the persistent period △ t for specifying.The elapsed time is being judged as the situation less than the persistent period △ t of regulation Under, return to step S11.On the other hand, in step S14, judge to make the applied voltage to the first electrochemical cell 51 as In the case that elapsed time after 1.1V is more than the persistent period △ t of regulation, into step S15.It is explained, in Fig. 5 institutes In the example for showing, after the elapsed time is judged in step S14 as more than the persistent period △ t of regulation, will be electrochemical to first The applied voltage for learning battery 51 maintains 1.1V (second voltage).

In step S15, ECU80 obtains the electric electrode current of the first electrochemical cell 51.Then, in step s 16, ECU80 judge the electric electrode current that obtains in step S15 whether on the basis of more than electric current It.Judging electric electrode current as base In the case of quasi- more than electric current It, into step S17.In step S17, ECU80 judges that the content of the sulfur composition in fuel is low In reference level, thereafter program is into step S19.On the other hand, electric current It on the basis of electric electrode current is judged in step s 16 In the case of below, into step S18.In step S18, ECU80 judges that the content of the sulfur composition in fuel contains higher than benchmark Amount, thereafter, program enters step S19.In step S19, ECU80 makes to become the applied voltage of the first electrochemical cell 51 0.30V, control program terminates.

It is explained, the detection process illustrated in Fig. 5 show and for first voltage and second voltage to be set to 1.1V's Situation.Assume, in the case where first voltage and second voltage are set to into different voltages, in step s 13 to apply on the first battery While making alive is set as first voltage, after more than the persistent period △ t for specifying is judged in step S14, by first Battery applied voltage is set as second voltage.

＜ second embodiments ＞

Then, with reference to Fig. 6 for the sulfur composition using sulfur component detection apparatus 2 second embodiment of the invention Detection method illustrate.Fig. 6 (A) is the same with Fig. 1 schematic of the sulfur component detection apparatus according to present embodiment Profile.Fig. 6 (B) is showing for the sulfur component detection apparatus according to present embodiment seen along the line A-A shown in Fig. 6 (A) Meaning property profile.Hereinafter, with regard to the sulfur component detection apparatus 2 according to second embodiment, main pair with according to the first embodiment party The part that the sulfur component detection apparatus 1 of formula are different illustrates.

Composition ＞ of ＜ sulfur component detection apparatus

As shown in Fig. 6 (B), it is also equipped with the first electrochemical cell according to the sulfur component detection apparatus 2 of second embodiment 51 vicinity and the second electrochemical cell 52 for setting.From Fig. 6 (A) and Fig. 6 (B), by the second electrochemical cell 52 with first Electrochemical cell 51 is configured side by side so as to which the distance away from the electrochemical cell 53 of diffusion rate key-course 16 and the 3rd is electric with first Chemical cell 51 is equal.

Specifically, in the present embodiment, element portion 10 also has the 3rd electrode 43 and the 4th electrode 44.It is electric by the 3rd Pole 43 is configured on the surface of the side of tested gas compartment 30 of the first solid electrolyte layer 11.Therefore, it is exposed to the 3rd electrode 43 Gas in tested gas compartment 30.On the other hand, the 4th electrode 44 is configured into the first air in the first solid electrolyte layer 11 On the surface of the side of room 31.Therefore, the gas (air) that the 4th electrode 44 is exposed in the first atmospheric air chamber 31 is made.By the 3rd electrode 43 Configured with clamping the first solid electrolyte layer 11 and mutually opposing mode with the 4th electrode 44.3rd electrode 43, the first solid Dielectric substrate 11 and the 4th electrode 44 constitute the second electrochemical cell 52.Therefore, it is the 3rd electrode 43 is arranged side by side with first electrode 41 Ground configuration so as to which the distance away from the electrochemical cell 53 of diffusion rate key-course 16 and the 3rd is equal with first electrode 41.

In the present embodiment, the material of the 3rd electrode 43 is constituted comprising platinum (Pt), golden (Au), lead (Pb), silver-colored (Ag) etc. Metallic element or their alloy are used as main component.Preferably, the 3rd electrode 43 be comprising platinum (Pt), golden (Au), lead (Pb), The porous cermet electrode of at least one of silver-colored (Ag) as main component.In addition, the 4th electrode 44 is comprising platinum (Pt) As the porous cermet electrode of main component.It is explained, the material for constituting the 3rd electrode 43 is not necessarily limited to above-mentioned material Material, as long as even if equal with applied voltage, the mode that the decomposition rate of SOx is reduced compared with first electrode 41 constitutes electrode, just It can be any material.Especially, in the present embodiment, the material for constituting the 3rd electrode 43 is preferably SOx in the 3rd electrode The speed being decomposed on 43 essentially become 0 as material.In addition, constitute the 4th electrode 44 material be not necessarily limited to it is above-mentioned Material, as long as oxide ion can be made when the voltage of regulation is applied between first electrode 41 and second electrode 42 first Move between electrode 41 and second electrode 42, it is possible to be any material.

Possesses second circuit 90 according to the sulfur component detection apparatus of second embodiment.Second circuit 90 possesses second source 91 and second galvanometer 92.The galvanometer 92 of second source 91 and second is connected to into ECU80.Second source 91 is in the 3rd electrode 43 And the 4th applied voltage between electrode 44 so that the current potential of the 4th electrode 44 becomes to be above the current potential of the 3rd electrode 43.By second The size of the voltage that power supply 91 applies is by ECU80 controls.

On the other hand, the second galvanometer 92 detects the electric current flowed between the 3rd electrode 43 and the 4th electrode 44 (also Be, the electric current of flowing in the first solid electrolyte layer 11) i.e. the size of electricity electrode current.To be obtained using the second galvanometer 92 Electric electrode current detected value input ECU80.

ECU80 can be controlled by second source 91 in the 3rd electrode 43 and the 4th electrode 44 by controlling second source 91 Between apply the 3rd applied voltage.Therefore, ECU80 and second source 91 are used as can be in the 3rd electrode 43 and the 4th electrode 44 Between apply inter-electrode voltage and control the voltage bringing device function of the inter-electrode voltage.In addition, to ECU80 input by It is corresponding with the size of the electric electrode current flowed between the 3rd electrode 43 and the 4th electrode 44 that second galvanometer 92 is detected Signal.Therefore, the electricity that ECU80 and the second galvanometer 92 flow as detection and between the 3rd electrode 43 and the 4th electrode 44 The test section function of the value of the related electric current relevant parameter of stream.

＜ Cleaning Principle ＞

As described above, in the second electrochemical cell 52, even if applying to apply with the identical of the first electrochemical cell 51 Voltage, the speed that the SOx contained in tested gas is decomposed is also very slow compared with the first electrochemical cell 51.Specifically, The speed that SOx is decomposed on the 3rd electrode 43 is very slow compared with the speed that SOx is decomposed in first electrode 41, substantially For 0.Therefore, it is also the suction on the 3rd electrode 43 that the decomposition product of the SOx for containing in tested gas is adsorbed in the speed of electrode Attached speed is slower than the adsorption rate in first electrode 41.Specifically, the decomposition product of SOx on the 3rd electrode 43 substantially Without absorption.Therefore, compared with the active reduction speed of the decomposition to water in first electrode 41, on the 3rd electrode 43 The decomposition to water active reduction speed it is slow.Specifically, the activity of the decomposition to water on the 3rd electrode 43 is basic On do not reduce.As a result, the electric electrode current in the second electrochemical cell 52 is not affected by the decomposition for being attributed to SOx.Cause This, compared with the electric electrode current in the first electrochemical cell 51, the electric electrode current in the second electrochemical cell 52 is big, tested The concentration of the SOx contained in gas is higher, and difference between currents are bigger between these electrodes.

Therefore, the sulfur component detection apparatus 2 of present embodiment are calculated the first of the first electrochemical cell 51 by ECU80 Electric electrode current when being applied with assigned voltage between electrode 41 and second electrode 42 with the 3rd of the second electrochemical cell 52 The difference of electric electrode current when being applied with same assigned voltage between the electrode 44 of electrode 43 and the 4th, and examined based on the difference Survey the sulfur composition contained in fuel.By the electric electrode current and the second electrochemical cell that so obtain the first electrochemical cell 51 When difference between currents are come the concentration for detecting SOx between 52 electrode, the shadow of the concentration change of the water contained in tested gas can be mitigated Ring.

It is explained, in the example shown in Fig. 6, the second electrochemical cell 52 and the first electrochemical cell 51 have first Solid electrolyte layer 11.But, the second electrochemical cell 52 can possess the first solid electricity for constituting the first electrochemical cell 51 Solid electrolyte layer beyond solution matter layer 11.

In addition, in the above-described embodiment, by the applied voltage of the first electrochemical cell 51 and to the second electrochemistry electricity The applied voltage in pond 52 is set to same voltage.But, as long as the applied voltage of the second electrochemical cell 52 is applied between electrode Added-time can by the water decomposition contained in tested gas and less than water carrying current region lower limit voltage, it is also possible to It is the voltages different from the applied voltage to the first electrochemical cell 51.

＜ sulfur composition detection processes ＞

According to the Cleaning Principle of sulfur composition as described above, in the present embodiment, sulfur composition is carried out in the following manner Detection process.

Additionally, in the present embodiment, in the sulfur composition contained in detecting fuel, ECU80 is to the first electrochemical cell 51 and the second electrochemical cell 52 apply first voltage.Then, to two electrochemical cells during the persistent period △ t of regulation 51st, 52 it is continuously applied first voltage.Thus, in the case that the content of the sulfur composition in fuel is more than moderate, SOx's Decomposition product adsorbs in large quantities in first electrode 41.On the other hand, even if in this case, the decomposition product of SOx exists Also do not adsorb on 3rd electrode 43.

Then, it is right if the elapsed time started from the applying of first voltage becomes more than the persistent period △ t of regulation First electrochemical cell 51 and the second electrochemical cell 52 apply second voltage.Now, if the content of the sulfur composition in fuel Few, then the decomposition product of SOx is few in the adsorbance of first electrode 41, thus the electric electrode current of the first electrochemical cell 51 with The difference of the electric electrode current t of the second electrochemical cell 52 becomes below predetermined reference value.Therefore, it is being applied with second The difference of electric electrode current during voltage be below predetermined reference value in the case of, judge that the sulfur composition in fuel contains Measure below the reference level for regulation.

Conversely, if the content of the sulfur composition in fuel were high, the difference of electric electrode current when being applied with second voltage Go above predetermined reference value.Therefore, the difference of the electric electrode current when second voltage is applied with is more than in advance really In the case of fixed reference value, the content for judging the sulfur composition in fuel is more than reference level.

Here, the distinct regions of the electric electrode current below reference value are set to into first area, the electricity of reference value is will be greater than The distinct regions of electrode current are set to second area.Therefore, second area can be referred to as the whole Current Zone beyond first area Domain.In the present embodiment, the difference of the electric electrode current when second voltage is applied with to the first electrochemical cell 51 is the During value in one region, judge on the basis of the content of sulfur composition in fuel below content.On the other hand, to the first electrochemistry When electric electrode current when battery 51 is applied with second voltage is the value in second area, the content of the sulfur composition in fuel is judged Higher than reference level.Therefore, in the present embodiment, the difference of the electric electrode current when second voltage is applied with is the firstth area During value in domain, when being judged to the value in for second area compared with, the content of the sulfur composition in fuel is low.

Should illustrate, in the above-described first embodiment, based on the first electrode 41 in the first electrochemical cell 51 and The content of the sulfur composition between the electrode flowed between two electrodes 42 in current detecting fuel.In addition, in above-mentioned second embodiment In, based on the electric electrode current flowed between the first electrode 41 and second electrode 42 of the first electrochemical cell 51 and second Sulfur during the difference of the electric electrode current of flowing is to detect fuel between 3rd electrode 43 of electrochemical cell 52 and the 4th electrode 44 The content of composition.Therefore, in these embodiments, it may be said that based on the first electrode 41 in the first electrochemical cell 51 and The SOx contained during the related electric current relevant parameter of the electric electrode current of flowing is to detect tested gas between second electrode 42.

In addition, as the electric current relevant parameter, these electric electrode currents, the difference of electric electrode current not only can be used, And can also use according to electric electrode current, its difference and the voltage, the resistance value that change.

Claims (4)

1. sulfur component detection method, its be by sulfur component detection apparatus detect the sulfur composition contained in fuel content sulfur into Point detection method, the sulfur component detection apparatus possess the first electrochemical cell, diffusion rate key-course and tested gas compartment, and this One electrochemical cell possesses the solid electrolyte layer with oxide ion conductive, on the one side of the solid electrolyte layer The first electrode of configuration and the second electrode configured on the another side of the solid electrolyte layer, the diffusion rate key-course The diffusion rate control of the tested gas for carrying out passing through, the tested gas compartment is by the solid electrolyte layer and the diffusion rate Key-course divides to be formed；The first electrode is configured in the tested gas room, while by the second electrode exposing Configure in the mode of air；The sulfur component detection method includes：

First for being continuously applied between the first electrode and the second electrode more than the decomposition beginning voltage of oxysulfide Voltage becomes operation more than setting up to the value of accumulative parameter,

Then the operation of the first voltage is applied, applying water disassembles between the first electrode and the second electrode Second voltage more than beginning voltage, while obtaining the electric current relevant parameter related to the electric electrode current flowed between these electrodes Value operation, and

The operation of the content of the sulfur composition in value detection fuel based on the electric current relevant parameter of the acquirement,

The accumulative parameter is that the value of the accumulative parameter becomes the integrated flow of oxysulfide more big, in waste gas and becomes more Parameter,

It is in first area in the value of the electric current relevant parameter of the acquirement in the operation of the sulfur composition in the detection fuel Value when, be judged to that with the value of the parameter of the acquirement be value in the Zone Full i.e. second area beyond the first area When compare, the content of the sulfur composition in fuel is low.

2. the sulfur component detection method described in claim 1, wherein, the size of the first voltage is big with the second voltage It is little equal.

3. the sulfur component detection method described in claim 1 or 2, wherein, the electric current relevant parameter is in the first electrode The electric current flowed and the second electrode between, the first area is region more than predetermined reference current, and institute It is less than the region of the predetermined reference current to state second area.

4. the sulfur component detection method described in claim 1 or 2, wherein, it is electrochemical that the sulfur component detection apparatus are also equipped with second Battery is learned, second electrochemical cell possesses the solid electrolyte layer with oxide ion conductive, in the solid electrolyte The 3rd electrode configured on the one side of layer and the 4th electrode configured on the another side of the solid electrolyte layer；By institute Three-electrode configuration is stated in the tested gas room, at the same by the 4th electrode to be exposed to air in the way of configure,

Constitute the first electrode and the 3rd electrode so that between the first electrode and the second electrode and When being applied with the first voltage between the 3rd electrode and the 4th electrode, the oxysulfide in the first electrode Decomposition rate becomes faster than the decomposition rate of the oxysulfide on the 3rd electrode,

The electric current relevant parameter be between the first electrode and the second electrode flow electric electrode current with institute The difference of the electric electrode current flowed between the 3rd electrode and the 4th electrode is stated, the first area is predetermined benchmark Value area below, while the second area is more than the region of the predetermined reference value.