JP4872840B2 - Sulfur component detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a sulfur component in an exhaust gas over a long period. <P>SOLUTION: A metal or a metallic compound 50, capturing a sulfur component in an exhaust gas is disposed in a flow path of an exhaust gas. When the sulfur component amount captured by the metal or the metallic compound 50 is increased with passage of time, physical properties of the metal or the metallic compound 50, changed according to the increase of the amount of captured sulfur component are measured for detecting the sulfur component in the gas from the measured physical properties. A regeneration control is executed for eliminating the captured sulfur component at the time the amount of the sulfur component captured by the metal or metallic compound 50 exceeds a predetermined amount. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a sulfur component detection apparatus.

Conventionally, an SO _x concentration sensor for detecting the SO _x concentration in exhaust gas is known. These known SO _x concentration sensors usually use a solid electrolyte, and measure the electromotive force generated when SO _x changes to sulfate ions to detect the SO _x concentration in the exhaust gas (for example, patents). Reference 1).
JP 2004-239706 A

However, the conventional sulfur component detection apparatus using such an SO _x concentration sensor operates only under high temperature, and the apparatus becomes large, especially when the SO _x concentration is low, the SO _x concentration cannot be detected. There's a problem. The SO in the conventional as _x concentration sensor has only been directed eye to detect SO _x concentration instantaneously, thus as long as it attempts to detect the SO _x concentration instantaneously various problems as mentioned above Inevitable.

Therefore, the present inventor changed his mind and turned not to detect the instantaneous SO _x concentration but to detect the integrated amount of SO _x discharged over a long period of time. It has been found that when the idea is changed in this way, the SO _x amount in the exhaust gas can be easily detected although it is the integrated amount of SO _x discharged over a long period of time.

Incidentally, it is possible to most appropriately apply the present invention when detecting the long integration amount of the SO _x amount discharged over a period is required. Even when the instantaneous SO _x concentration cannot be detected, it is sufficient if the average value of the SO _x concentration in a certain period or the average value of the discharged SO _x amount in a certain period is sufficient. The present invention can be applied.

According to the present invention, in the sulfur component detection device for detecting the sulfur component contained in the exhaust gas, the SOx sensor is provided , and the detection unit of the SOx sensor is arranged in the exhaust gas flow passage, and the detection of the SOx sensor is performed. In the section, a metal or a metal compound whose electric resistance and heat capacity change as the amount of the sulfur component trapped in the exhaust gas is increased and the amount of the trapped sulfur component is increased, and either of the electric resistance and heat capacity of the metal or metal compound is arranged. It has means for detecting the amount of sulfur component trapped in the metal or metal compound from the measured electrical resistance or heat capacity by measuring either one, the amount of sulfur component detected is a predetermined amount When exceeded, increase the temperature of the metal or metal compound, or increase the temperature of the metal or metal compound and enrich the air-fuel ratio of the exhaust gas. By doing so, the sulfur component trapped by the metal or metal compound is removed.

  The sulfur component in the exhaust gas can be easily detected over a long period of time.

FIG. 1 shows an overall view of a compression ignition type internal combustion engine.
Referring to FIG. 1, 1 is an engine body, 2 is a combustion chamber of each cylinder, 3 is an electronically controlled fuel injection valve for injecting fuel into each combustion chamber 2, 4 is an intake manifold, and 5 is an exhaust manifold. Respectively. The intake manifold 4 is connected to the outlet of the compressor 7 a of the exhaust turbocharger 7 through the intake duct 6, and the inlet of the compressor 7 a is connected to the air cleaner 8. A throttle valve 9 driven by a step motor is arranged in the intake duct 6, and a cooling device 10 for cooling intake air flowing in the intake duct 6 is arranged around the intake duct 6. In the embodiment shown in FIG. 1, the engine cooling water is guided into the cooling device 10 and the intake air is cooled by the engine cooling water.

On the other hand, the exhaust manifold 5 is connected to the inlet of the exhaust turbine 7 b of the exhaust turbocharger 7, and the outlet of the exhaust turbine 7 b is connected to the inlet of the SO _x trap catalyst 11. Further, the outlet of the SO _x trap catalyst 11 is connected to the NO _x storage catalyst 12. As shown in FIG. 1, an SO _x sensor 13 for detecting a sulfur component contained in the exhaust gas, that is, SO _x , is disposed downstream of the SO _x trap catalyst 11. A fuel addition valve 14 for adding fuel to the exhaust gas is disposed in the exhaust manifold 5.

  The exhaust manifold 5 and the intake manifold 4 are connected to each other via an exhaust gas recirculation (hereinafter referred to as EGR) passage 15, and an electronically controlled EGR control valve 16 is disposed in the EGR passage 15. A cooling device 17 for cooling the EGR gas flowing in the EGR passage 15 is disposed around the EGR passage 15. In the embodiment shown in FIG. 1, the engine cooling water is guided into the cooling device 17, and the EGR gas is cooled by the engine cooling water. On the other hand, each fuel injection valve 3 is connected to a common rail 19 through a fuel supply pipe 18. Fuel is supplied into the common rail 19 from an electronically controlled variable discharge amount fuel pump 20, and the fuel supplied into the common rail 19 is supplied to the fuel injection valve 3 via each fuel supply pipe 18.

The electronic control unit 30 is composed of a digital computer, and is connected to each other by a bidirectional bus 31. A ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a CPU (Microprocessor) 34, an input port 35 and an output port 36. It comprises. As shown in FIG. 1, a load sensor 41 that generates an output voltage proportional to the depression amount L of the accelerator pedal 40 is connected to the accelerator pedal 40, and the output voltage of the load sensor 41 passes through a corresponding AD converter 37. Input to the input port 35. Further, the input port 35 is connected to a crank angle sensor 42 that generates an output pulse every time the crankshaft rotates, for example, 15 °. On the other hand, the output port 36 of the fuel injection valve 3 via a corresponding drive circuit 38, the step motor for driving the throttle valve 9 is connected to the fuel addition valve 14, EGR control valve 16 and the fuel pump 20.

First, the NO _x storage catalyst 12 shown in FIG. 1 will be described. This NO _x storage catalyst 12 absorbs NO _x when the air-fuel ratio of the exhaust gas is lean, and the air-fuel ratio of the exhaust gas is the stoichiometric air-fuel ratio or rich. Then, it has a function of releasing absorbed NO _x . In the compression ignition type internal combustion engine, the air-fuel ratio of the exhaust gas is lean, and therefore NO _x normally contained in the exhaust gas is stored in the NO _x storage catalyst 12.

However Thus becomes saturated is _the NO _x storage capacity of the NO _x storage catalyst 12 during the combustion of the fuel under a lean air-fuel ratio is continued, the NO _x by _the NO _x storage catalyst 12 and thus It can no longer be absorbed. Therefore, in the embodiment shown in FIG. 1, before the storage capacity of the NO _x storage catalyst 12 is saturated, for example, the fuel is injected into the combustion chamber 2 during the exhaust stroke, or the fuel is supplied from the fuel addition valve 14 into the exhaust gas. temporarily rich air-fuel ratio of the exhaust gas by the addition of, thereby so that to release NO _x from _the NO _x storage catalyst 12.

However, the exhaust gas contains SO _x, namely SO _2, the SO ₂ When this SO ₂ flows into the _the NO _x storage catalyst 12 is occluded in _the NO _x storage catalyst 12. In this case, NO _x amount _the NO _x storage catalyst 12 when the amount of occluded SO _x increases may occlude gradually decreases. Therefore, in the embodiment shown in Figure 1 captured SO _x contained in the exhaust gas by this _the SO _x trapping catalyst 11 to place _the SO _x trapping catalyst 11 upstream of _the NO _x storage catalyst 12, whereby _the NO _x storage The inflow of SO _x into the catalyst 12 is suppressed.

By the way, when the integrated value of the SO _x amount stored in the NO _x storage catalyst 12 affects the NO _x purification action, it is necessary to detect the integrated value of the stored SO _x amount. However, in practice, it is difficult to obtain the integrated value of the occluded SO _x amount. Therefore, in the present invention, the integrated value of the sulfur component in the exhaust gas that represents the integrated value of the stored SO _x amount is detected by the SO _x sensor 13. Next, the method for detecting a sulfur component according to the present invention will be described.

FIG. 2 shows the principle of detection of sulfur components according to the present invention. In the present invention, a metal or a metal compound capable of capturing a sulfur component in the exhaust gas is disposed in the exhaust gas flow passage, and in the embodiment shown in FIG. 1, a metal or a metal compound capable of capturing SO _x in the exhaust gas is disposed. The This metal or metal compound is schematically indicated by reference numeral 50 in FIG. The metal or metal compound 50 shown in FIG. 2A is made of a metal or metal compound that does not contain sulfur. In an embodiment according to the present invention, the metal or metal compound 50 comprises an alkali metal, an alkaline earth metal, a rare earth metal, a noble metal or a compound of these metals.

Next, a method for detecting a sulfur component will be described by taking as an example the case where barium Ba, which is one of the alkaline earth metals, or a compound thereof is used as the metal or metal compound 50.
Barium Ba is barium oxide BaO in the atmosphere. When this barium oxide BaO is placed in the exhaust gas, it is immediately changed to barium carbonate BaCO ₃ by CO or CO ₂ contained in the exhaust gas. Further, the barium carbonate BaCO ₃ is changed to barium nitrate Ba (NO ₃ ) ₂ by NO _x contained in the exhaust gas.

That is, when barium Ba is used, the metal or metal compound 50 shown in FIG. 2A is barium oxide BaO, barium carbonate BaCO _3, or barium nitrate Ba (NO ₃ ) ₂ , and this metal or metal When the compound 50 is placed in the exhaust gas, it becomes barium nitrate Ba (NO ₃ ) ₂ . Generally expressed, the metal or metal compound 50 shown in FIG. 2A is made of oxide, carbonate, or nitrate, and when this metal or metal compound 50 is placed in exhaust gas, it becomes nitrate. .

On the other hand, small but a Sulfur component compared to CO and HC and NO _x in the exhaust gas, that is, contains SO _x, this SO _x is trapped in the metal or metal compound 50 FIG 2 (A) The metal compound 51 containing sulfur is changed as shown in FIG. When barium Ba is used, the sulfur-containing metal compound 51 is barium sulfate BaSO ₄ . Therefore, when the metal or the metal compound 50 is placed in the exhaust gas, as shown in FIG. 2B, a part of the metal compound 50 made of barium nitrate Ba (NO ₃ ) _{2 is} barium nitrate Ba (NO ₃ ) ₂ changes to barium sulfate BaSO ₄ . Generally speaking, a part of nitrate is changed to sulfate. In this case, the ratio of the sulfate in the metal compound 51 increases as time elapses, that is, as the amount of the trapped sulfur component increases.

  On the other hand, FIG. 2C shows a case where the metal or metal compound 50 is made of a noble metal or a compound thereof. As this noble metal, palladium Pd, rhodium Rh or platinum Pt can be used, and FIG. 2C shows a case where palladium Pd is used as an example. In this case, when the sulfur component is captured, the metal oxide PdO changes to sulfide PdS.

  When nitrate is changed to sulfate, or metal oxide is changed to sulfide, the physical properties change. Therefore, it is possible to estimate the amount of captured sulfur component, that is, the amount of sulfur component in the gas, from the change of physical property. it can. Therefore, in the present invention, the physical property of the metal compound 51 is measured when the metal or the metal compound 50 not containing sulfur is changed to the metal compound 51 containing sulfur with the passage of time, and the sulfur component in the gas is measured from the measured physical property. To detect.

  In other words, in the present invention, in other words, when the amount of the sulfur component trapped by the metal or the metal compound 50 increases with time, the metal or the metal that changes as the amount of the trapped sulfur component increases. By measuring the physical properties of the metal compound 50, the sulfur component in the exhaust gas is detected from the measured physical properties.

  Next, a physical property to be measured and a typical detection method corresponding to the physical property to be measured will be described with reference to FIGS. 3 to 6 will be described by taking as an example the case where nitrate is changed to sulfate as shown in FIG. 2B.

FIG. 3 shows a case where the measured physical property is an electrical physical property and the measured electrical physical property is an electrical resistance.
FIG. 3A shows the relationship between the trapped amount W of sulfur S and the electrical resistance value R. As shown in FIG. 3A, the electrical resistance value R increases as the trapped amount W of sulfur S increases, that is, as the amount of change from nitrate to sulfate increases. Therefore, the trapped amount W of sulfur S, that is, the integrated value of the SO _x amount in the exhaust gas can be obtained from the electric resistance value R.

FIG. 3B shows a detection unit of the SO _x sensor 13 shown in FIG. As shown in FIG. 3B, the detection portion of the SO _x sensor 13 disposed in the exhaust gas flow path includes a detection metal compound piece 53 supported by a pair of terminals 52 and a pair of terminals 54. A supported reference metal compound piece 55 is provided. Further, a temperature sensor 56 is disposed in the detection part of the SO _x sensor 13. The detection metal compound piece 53 is formed from an oxide, carbonate, or nitrate, and the reference metal compound piece 55 is formed from a sulfate. When the exhaust gas flows, the reference metal compound piece 55 does not change, but when the detection metal compound piece 53 is not nitrate, it changes to nitrate, and then the nitrate gradually changes to sulfate due to SO _x contained in the exhaust gas. To do. Thus, the electrical resistance value R of the metal compound piece 53 for detection gradually increases.

  The electrical resistance value R of the metal compound piece for detection 53 increases as the ambient temperature increases. Therefore, a reference metal compound piece 55 is provided in order to eliminate the influence of such a temperature change on the electric resistance value R. For example, a Wheatstone bridge as shown in FIG. 3C is used for detection. The amount of sulfur S trapped is determined from the difference between the electrical resistance value of the metal compound piece 53 and the electrical resistance value of the reference metal compound piece 55. When the Wheatstone bridge as shown in FIG. 3C is used, the voltage V appearing in the voltmeter 57 decreases as the amount of collected sulfur S increases as shown in FIG.

4 to 6 show cases where the measured physical properties are thermal properties and the measured thermal properties are heat capacity and thermal conductivity.
As shown in FIG. 4A, the heat capacity of the metal compound piece decreases as the trapped amount W of sulfur S increases. Therefore, as shown in FIG. 4B, when the temperature around the metal compound piece rises, the increase rate of the center temperature of the metal compound piece increases as the trapped amount W of sulfur S increases.

FIG. 5A shows the detection unit of the SO _x sensor 13. In the example shown in FIG. 5A, a detection thermistor element 59 having a pair of lead wires 58 and a reference thermistor element 62 having a pair of lead wires 61 are provided. Further, in this example, the periphery of the detection thermistor element 59 is surrounded by the detection metal compound 60, and the periphery of the reference thermistor element 62 is surrounded by the reference metal compound 63.

  In this example, the heat capacity of the detection metal compound 60 is estimated from the responsiveness of the change in resistance value of the detection thermistor element 59 when the temperature around the detection metal compound 60 changes, and the temperature around the reference metal compound 63 is The heat capacity of the reference metal compound 63 is estimated from the responsiveness of the change in the resistance value of the reference thermistor element 62 when changed, and the trapped amount W of sulfur S is obtained from the difference between these heat capacities.

  More specifically, the difference between the resistance value of the detection thermistor element 59 and the resistance value of the reference thermistor element 62 is obtained in the form of voltage using a Wheatstone bridge as shown in FIG. . In this case, the voltage V of the voltmeter 64 showing the difference in resistance value decreases as the sulfur S captured by the detection metal compound 60 increases as shown in FIG. Further, the temperature of the metal compound for detection 63 is detected from the voltage of the voltmeter 65.

  On the other hand, in the example shown in FIG. 6, heaters 66 and 67 for heating the detection metal compound 60 and the reference metal compound 63 are provided. In this example, the temperatures of the detection metal compound 60 and the reference metal compound 63 can be increased by causing the heaters 66 and 67 to generate heat.

Now, the detection metal compounds 53 and 60 do not continue to capture sulfur permanently, and when the sulfur capturing ability is saturated, sulfur cannot be captured any more. Accordingly then the capturing capacity of sulfur is saturated not E detects the amount of SO _x in the exhaust gas. Therefore, in the present invention, as shown in FIG. 7, regeneration control for removing the sulfur component captured when the amount W of sulfur component captured by the detection metal compounds 53, 60 exceeds a predetermined amount. Like to do.

  This reproduction control is performed as follows, for example. That is, the detection metal compounds 53 and 60 release sulfur components when the air-fuel ratio of the exhaust gas is approximately 1300 ° C. or higher when the sulfate is thermally decomposed under lean conditions, and the air-fuel ratio of the exhaust gas is rich. Then, it has a property of releasing a sulfur component at about 600 ° C. or higher.

  Therefore, when it should be regenerated, for example, the temperature of the detection metal compounds 53 and 60 is increased to a sulfur release temperature at which the sulfur component captured under the rich air-fuel ratio of the exhaust gas can be released, that is, 600 ° C. or higher. In this state, regeneration control is performed by making the air-fuel ratio of the exhaust gas rich. Alternatively, regeneration control is performed by raising the temperature of the detection metal compounds 53 and 60 to a sulfur release temperature at which the sulfur component captured under the lean air-fuel ratio of the exhaust gas can be released, that is, 1300 ° C. or higher. .

In this case, using the SO _x sensor with heater shown in FIG. 6 as SO _x sensor 13, a heater 66 and 67 when the temperature of the metal compound for detection 53, 60 reaches a temperature slightly lower than the sulfur release temperature The temperature of the detection metal compounds 53 and 60 can be raised to the sulfur release temperature by generating heat, whereby the detection metal compounds 53 and 60 can be regenerated.

Next, conditions for starting reproduction control will be described.
As described above, the detection metal compounds 53 and 60 change from oxide, carbonate, or nitrate to sulfate with the passage of time. Accordingly, in the example according to the present invention, as shown in FIG. 8A, the difference ΔF between the physical property value FX when the metal compound is made of sulfate and the measured physical property value F of the metal compound is less than the allowable value. Sometimes playback control is performed. More specifically, regeneration control is performed when the difference ΔF between the physical property value FX of the reference metal compounds 55 and 63 and the physical property value F of the detection metal compounds 53 and 60 falls below an allowable value.

  Further, the amount of the sulfur component captured by the detection metal compounds 53 and 60 can be estimated from the operating state of the engine. Accordingly, in another embodiment according to the present invention, as shown in FIG. 8B, the difference ΔW between the sulfur component trapping amount WX estimated from the engine operating state and the sulfur component trapping amount W determined from the measured physical properties. Regeneration control is performed when becomes greater than the allowable value.

Next, a method for estimating the amount of trapped sulfur components will be described with reference to FIGS. 9 and 10.
Sulfur is contained in the fuel in a certain proportion, and therefore the amount of sulfur component discharged from the engine is proportional to the fuel injection amount. The fuel injection amount is a function of the required torque and the engine speed, and therefore the amount of sulfur component discharged from the engine is also a function of the required torque and the engine speed. In the embodiment according to the present invention, the amount SOXA of the sulfur component discharged from the engine per unit time is stored in advance in the ROM 32 as a function of the required torque TQ and the engine speed N in the form of a map as shown in FIG. Has been.

  In addition, the lubricating oil contains sulfur at a certain ratio, and the amount of lubricating oil combusted in the combustion chamber 2, that is, the amount of sulfur component discharged from the engine is also a function of the required torque and the engine speed. Become. In the embodiment according to the present invention, the amount SOXB of the sulfur component contained in the lubricating oil and discharged from the engine per unit time as a function of the required torque TQ and the engine speed N is shown in a map as shown in FIG. The accumulated amount ΣSOX of the sulfur component discharged from the engine is calculated by accumulating the sum of these sulfur component amounts SOXA and SOXB.

FIG. 10 shows a routine for estimating the amount of sulfur trapped by the detection metal compounds 53 and 60. This routine is executed by interruption every predetermined time.
Referring to FIG. 10, first, at step 70, the amounts of sulfur components SOXA and SOXB discharged from the engine per unit time are read from FIGS. 9 (A) and 9 (B). Next, at step 71, the sum of these SOXA and SOXB is added to the sulfur component amount ΣSOX. On the other hand, the integrated amount of the sulfur component captured by the detection metal compounds 53 and 60 is proportional to the integrated amount ΣSOX of the sulfur component discharged from the engine. Accordingly, in step 72, the cumulative amount WX of the sulfur component trapped in the detection metal compounds 53, 60 is estimated by multiplying the cumulative amount ΣSOX of the sulfur component discharged from the engine by the proportional constant C.

  FIG. 11 shows a first embodiment of the reproduction control. In this embodiment, first, at step 80, it is determined whether or not a condition to be reproduced is satisfied. That is, whether or not the difference ΔF in the physical property values shown in FIG. 8 (A) is less than the allowable value, or whether the difference ΔW in the sulfur component capture amount shown in FIG. 8 (B) is greater than or equal to the allowable value. Is determined. When playback is to be performed, the process proceeds to step 81 where playback processing is performed.

12 and 13 show another embodiment of the reproduction control.
In this embodiment, the temperature T of the detection metal compounds 53 and 60 is detected, and when the temperature T of the metal compounds 53 and 60 becomes higher than the sulfur release temperature TS, the difference ΔF in physical properties shown in FIG. 8A. 8 or more than the allowable value, or even if the difference ΔW in the sulfur component capture amount shown in FIG. 8B is less than or equal to the allowable value, the amount W of the sulfur component captured by the metal compounds 53 and 60 Reproduction control is performed if the value exceeds a predetermined fixed amount WS.

That is, in this embodiment, as shown in the regeneration control routine of FIG. 13, first, in step 90, the sulfur component of the detection metal compound 53, 60 calculated from the physical property value of the detection metal compound 53, 60 is captured. It is determined whether or not the amount W is larger than a fixed value WS shown in FIG. Detector temperature of trapped amount W is SO _x sensor 13 proceeds to step 91 when more than a certain value WS, i.e. the temperature T is determined whether or not higher than the sulfur release temperature TS of the metal compound for detection 53, 60 Is done. When T> TS, the routine proceeds to step 92 where regeneration processing of the metal compounds for detection 53, 60 is performed.

It is a figure which shows a compression ignition type internal combustion engine. It is a figure for demonstrating the detection principle of a sulfur component. It is a figure for demonstrating the detection method of a sulfur component. It is a figure for demonstrating the detection method of a sulfur component. It is a figure for demonstrating the detection method of a sulfur component. It is a figure for demonstrating the detection method of a sulfur component. It is a figure which shows the timing of reproduction | regeneration control. It is a figure for demonstrating the start conditions of reproduction | regeneration control. It is a figure which shows the map of the quantity of the sulfur component discharged | emitted from an engine. It is a flowchart for estimating the capture amount of a sulfur component. It is a flowchart for performing reproduction | regeneration control. It is a figure which shows the timing of reproduction | regeneration control. It is a flowchart for performing reproduction | regeneration control.

Explanation of symbols

13 SO _x sensor 53 Metal compound piece for detection 55 Metal compound piece for reference

Claims (7)

In a sulfur component detection device for detecting a sulfur component contained in exhaust gas, an SOx sensor is provided and a detection part of the SOx sensor is disposed in an exhaust gas flow passage, and the exhaust gas is disposed in the detection part of the SOx sensor. A metal or metal compound whose electric resistance and heat capacity change as the amount of the sulfur component trapped and the amount of the trapped sulfur component increases is placed, and either the electric resistance or heat capacity of the metal or metal compound is measured. Means for detecting the amount of sulfur component captured by the metal or metal compound from the measured electric resistance or heat capacity, and the amount of the detected sulfur component exceeds a predetermined amount Sometimes the temperature of the metal or metal compound is raised or the temperature of the metal or metal compound is raised and the air-fuel ratio of the exhaust gas is made rich. The sulfur component detection apparatus by which the sulfur component trapped by the metal or metal compound is removed . The metal compound changes from oxide or carbonate or nitrate to sulfate over time, and the difference between the electrical resistance when the metal compound is made of sulfate and the measured electrical resistance of the metal compound , Alternatively, the amount of sulfur component captured by the metal compound when the difference between the heat capacity when the metal compound is made of sulfate and the measured heat capacity of the metal compound is less than an allowable value is a predetermined amount. The sulfur component detection device according to claim 1, which is determined to have exceeded. The amount of sulfur component captured by the metal or metal compound is estimated from the engine operating state, and the estimated amount of sulfur component captured and the amount of sulfur component captured determined from the measured electrical resistance or heat capacity . The sulfur component detection device according to claim 1, wherein when the difference is greater than or equal to an allowable value, it is determined that the amount of the sulfur component captured by the metal compound exceeds a predetermined amount. The temperature of the metal or metal compound, the air-fuel ratio of the exhaust gas with raised to the sulfur release temperature capable of releasing the sulfur component that captured under rich the metal or by the air-fuel ratio of the exhaust gas rich The sulfur component detection apparatus according to claim 1, wherein the sulfur component captured by the metal compound is removed . The sulfur component captured by the metal or metal compound is removed by raising the temperature of the metal or metal compound to a sulfur release temperature at which the sulfur component captured under the lean air-fuel ratio of the exhaust gas can be released. The sulfur component detection apparatus according to claim 1. The metal compound for detection which changes into a sulfate when the metal compound captures sulfur and the reference metal compound made of sulfate, and the measured electrical resistance of the metal compound for detection and the measured reference metal compound 2. The sulfur according to claim 1 , wherein the sulfur component in the exhaust gas is detected from the difference between the electrical resistance of the gas and the difference between the measured heat capacity of the detection metal compound and the measured heat capacity of the reference metal compound. Component detection device. The sulfur component detection device according to claim 1 , wherein the metal or metal compound is an alkali metal, an alkaline earth metal, a rare earth metal, a noble metal, or a compound of these metals .

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