JP2008164474A - Particulate matter measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten measuring time by a filter combustion method. <P>SOLUTION: A particulate matter measuring apparatus is provided with: a heating furnace R; a connecting piping 10 extending from the heating furnace R; and a filter holding chamber 9 connected to a tip of the connecting piping 10. A heating gas guided to the heating furnace R and heated to a high temperature is passed through the connecting piping 10 to flow in the filter holding chamber 9 and sprayed to a collecting filter F held in its inside to vaporize or burn particulate matter in engine exhaust gases collected in the collecting filter F. A gas outlet part 75 of the heating furnace R is provided with such a shape that its inner diameter is gradually reduced toward its tip and that the inner diameter of the tip is smaller than the inner diameter of the connecting piping. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a particulate matter measuring apparatus that measures the mass, components, and the like of particulate matter contained in engine exhaust gas.

  Conventionally, a filter is one of the well-known mass measuring methods for particulate matter (also referred to as PM: Particulate Matters, also referred to as PM in this specification), which is one of exhaust materials from an engine. There is a mass method. The filter mass method is a method of collecting a PM by arranging a filter on a flow path of engine exhaust gas, and weighing the mass of the collected PM. In a PM in which a specific standard substance does not substantially exist, Since the mass can be directly measured, it is known that the reliability and accuracy of measurement can be expected.

More recently, a mass measurement method called a filter combustion method has been developed, in which the PM collected by a filter is burned and the gas concentration is analyzed to calculate the mass of the original PM. This filter combustion method has a high correlation with the measurement by the filter mass method, and can measure even a minute amount of PM exceeding the limit of weighing by the filter mass method, and also stabilizes the filter moisture content. Since it is unnecessary, there is an advantage that the measurement can be performed in a relatively short time without trouble.
JP 2006-153896 A

  However, even this filter combustion method requires a plurality of processes of collecting PM with a filter, heating it, analyzing the gas generated there, and cooling the filter, so that the total The time required for the measurement takes about 30 seconds to several minutes in the case of one filter. The present invention has been made in view of such problems, and it is possible to ultimately perform continuous measurement by combining filter collection and a combustion method and reducing the measurement time by the filter combustion method at that time. This is the main desired task.

  That is, the particulate matter measuring device according to the present invention includes a heating furnace, a connection pipe extending from the heating furnace, and a filter holding chamber connected to the tip of the connection pipe, and is guided to the heating furnace. The heated heating gas passes through the connecting pipe, flows into the filter holding chamber, is blown to the collection filter held inside, and is collected in the engine exhaust gas collected by the collection filter. The gas outlet portion of the heating furnace has a shape in which the inner diameter gradually decreases toward the tip, and the tip inner diameter is smaller than the inner diameter of the connection pipe. It is an eggplant.

  In addition, the heating furnace according to the present invention heats the filter by blowing the high-temperature gas to the filter in the filter holding chamber connected through the connection pipe while heating the gas passing through the inside. Then, the gas outlet part is characterized in that the inner diameter gradually decreases toward the tip, and the tip inner diameter is smaller than the inner diameter of the connection pipe.

  If it is such, the gas for a heating which came out of the heating furnace will advance as a thin flux, and will hardly contact the inner surface of a connection piping in the middle until it is sprayed on a filter. And between the inner surface of the connection pipe and the flux, the fluid is stagnant.

  Therefore, even when the temperature of the connecting pipe is kept low, the heating gas is combined with the heat insulating effect by the stagnant fluid, and the temperature heated in the heating furnace is almost not taken away by the connecting pipe. The filter is reached while keeping it. As a result, it is possible to raise the temperature of the filter very quickly as compared with the conventional case, to promote the vaporization or combustion of PM, and to shorten the measurement time.

  In order to efficiently transfer heat to the heating gas, a heat storage member that forms a plurality of conglomerates or integrates a plurality of conglomerate members is disposed in the internal flow path of the heating furnace. Is preferred.

  In a configuration in which exhaust gas is guided to the filter holding chamber and particulate matter is collected by the filter, measurement errors may occur if the PM trapping concentration is greatly affected by heat from the heating furnace. In order to avoid such a phenomenon as much as possible, it is desirable that the heating gas is blown against the filter from the direction opposite to the exhaust gas passage direction.

  According to the present invention having such a configuration, in the filter combustion method, the vaporization / combustion time of the particulate matter can be significantly shortened, so that the total measurement time can be shortened.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  <First Embodiment>

As shown in FIG. 1, the particulate matter measuring apparatus 100 is arranged such that a heated gas, that is, N ₂ gas and O ₂ gas, is separated from the PM collected by the filter F in this order. The mass of CO ₂ and NO ₂ contained in the gas that has been sprayed and vaporized / combusted is measured by an analysis unit such as NDIR (not shown in FIG. 1). The mass of SOF, sulfate, and soot constituting PM can be calculated from the CO ₂ amount and SO ₂ amount at this time.

  In FIG. 1, the symbol R is a heating furnace that passes the heating gas and raises the temperature thereof. As shown in the figure, the heating furnace R has a pipe line 71 forming an internal flow path, a heater 72 wound around the pipe 71, and a heat insulating material 73 provided around the heater 72. And a plurality of heat-resistant ceramic balls (for example, SiC spheres) 74 which are heat storage members disposed in the pipe 71. Then, by heating the pipe 71 and the ceramic ball 74 to a predetermined temperature by the heater 72, the heating gas passing through the heating furnace R is given heat from the pipe 71 and the ceramic ball 74, and the temperature thereof is increased. Rises.

  Reference numeral 9 denotes a filter holding chamber that holds a filter (also referred to as a collection filter) F. The filter F is a thin plate formed of, for example, quartz that does not change even at high temperatures. The filter F is disposed in the filter holding chamber 9 so that its surface is orthogonal to the flow direction of the heating gas.

  Reference numeral 10 denotes a connecting pipe that connects the filter holding chamber 9 and the heating furnace R, and has a straight cylindrical shape with a constant inner diameter. Note that it is not preferable to raise the temperature of the connection pipe 10 because it is connected to the filter holding chamber 9. This is because a measurement error may occur if the temperature of the filter F rises at a time other than the time of analysis and vaporization of PM occurs.

  With the above-described configuration, the high-temperature gas that has exited from the gas lead-out portion 75 of the heating furnace R flows into the filter holding chamber 9 through the connection pipe 10 and is blown to the filter F inside.

  Thus, in this embodiment, the gas outlet 75 of the heating furnace R has a hollow conical shape that narrows toward the tip. More specifically, the inner diameter of the gas outlet 75 is gradually reduced toward the tip, and the tip inner diameter is configured to be smaller than the inner diameter of the connection pipe 10. Note that the tip of the gas outlet 75 is configured to be at least on the inner side or the same surface as the heat insulating material 73 or the heater 72. This is to prevent the gas outlet 75 from protruding outside and being cooled. The ceramic ball 74 is configured such that a part of the ceramic ball 74 is accommodated in the gas lead-out portion 75 and disposed near the tip thereof.

  If this is the case, the heating gas emitted from the heating furnace R travels as a thin flux on the central axis C of the connecting pipe 10 as shown in FIG. It is sprayed and spreads over the entire surface of the collection filter F. In the middle of this, the inner surface of the connection pipe 10 is hardly contacted, and a slightly peeled gas remains between the inner surface of the connection pipe 10 and the flux, and a state close to a vacuum is obtained. This is a result confirmed by simulation.

  Therefore, even if the temperature of the connecting pipe 10 is kept low, the heating gas is heated by the heating furnace R without being deprived of heat by the connecting pipe 10 due to the heat insulating effect of the vacuum space. In this way, it is sprayed to the collection filter F, and the temperature of the collection filter F can be increased much faster (twice or more) than before, and the vaporization or combustion of PM can be promoted. In addition, since the PM vaporization or combustion time can be shortened, the gas analysis time can be shortened.

  In addition, since the temperature of the connection pipe 10 may be kept low, the heat influence on the filter holding chamber 9 and the filter F connected to the connection pipe 10 can be reduced in the PM concentration, and vaporization in the PM concentration. Measurement accuracy can be assured.

  Second Embodiment

  The particulate matter measuring device 100 according to the first embodiment has only described the configuration centered on the heating furnace and the filter holding unit, but this second example of the overall configuration including this configuration is also described in this second example. This will be described in the embodiment. In the following reference numerals, the same reference numerals are given to the members corresponding to the first embodiment. However, in the second embodiment, the heating furnace and the filter are used in a plurality, respectively. Is changed from R to R1, R2, and R3, and the filter is changed from F to F1, F2, and F3.

  As shown in FIG. 2, the particulate matter measuring device 100 according to the second embodiment measures the mass of PM contained in the exhaust gas of the engine 200 that is an internal combustion engine, and the exhaust pipe of the engine 200. A part of the exhaust gas that is connected to the engine 201 and is discharged from the engine 200 during operation is introduced directly or diluted by the dilution unit 300.

  More specifically, the internal structure of the particulate matter measuring device 100 will be described. As shown in FIG. 3, the particulate matter measuring device 100 is an introduction port into which exhaust gas from the engine 200 in the operating state is introduced. PI1, collection passages L11, L12, and L13 branched from the introduction port PI1, and collection filters F1, F2, and F3 for collecting PM provided in the branched passages L11, L12, and L13, respectively. And the filters F1, F2, and F3 in the order of the collection state in which the exhaust gas passes, the heating state in which the collected PM is heated to vaporize or burn, and the cooling state in which it is cooled. A state transition mechanism 6 that shifts by shifting, and an analysis unit 3 that communicates with the filter in the heated state and analyzes gas generated by vaporization or combustion of PM.

  The collection filters F1, F2, and F3 are made of a material having high heat resistance such as quartz that does not change itself or generate gas even when PM is burned.

  Next, the in-device fluid circuit configuration including the passage channels L11, L12, L13 and the like for generating the collection state, the heating state, and the cooling state will be described.

  First, a collection state generation circuit necessary for creating a collection state will be described. This circuit includes the exhaust gas introduction port PI1, passage passages L11, L12, L13 branched from the exhaust gas introduction port PI1, and collection filters F1, F2, F3 in the passage passages L11, L12, L13. The first open / close valves V11, V12, and V13 are provided downstream of each. Further, the passage passages L11, L12, and L13 merge to form one integrated passage L downstream of the valves V11, V12, and V13, and the integrated passage L is connected to the exhaust port PO. On the integrated flow path L, a constant flow rate device 4 for flowing a constant flow rate Qall such as a Venturi tube and a suction pump 5 such as a Roots blower are provided and located at an exhaust port PO.

  In such a configuration, by opening any one valve V11 (V12, V13) and closing the other valves V12, V13 ((V11, V13), (V11, V12)), the opened valve V11 is opened. The exhaust gas flows only into the passage channel L11 (L12, L13) provided with (V12, V13), and the corresponding collection filter F1 (F2, F3) is in the collection state.

  The heating state generation circuit necessary for creating the heating state is divided into an inflow port PI2 into which the heated heating gas flows in, and three branches in the middle of the extension from the inflow port PI2, and each passage flow path L11, L12. Gas flow paths L21, L22, L23 connected to the downstream of the collection filters F1, F2, F3 of L13 and upstream of the first on-off valves V11, V12, V13, and the respective heating gases Heating furnaces R1, R2, R3 provided on the flow paths L21, L22, L23, and second opening / closing valves V21, V22 provided on the front side of the heating furnaces R1, R2, R3, that is, on the inflow port PI2 side, V23. Further, a heating gas flow rate control means 11 is provided on the heating gas flow path L2 before branching, and the heating gas flow rate Q1 is controlled to be constant.

  In such a configuration, when only one of the second on-off valves V21 (V22, V23) is opened, the heating gas heated through the heating furnace R1 (R2, R3) becomes the corresponding passage flow path L11. (L12, L13) flows into the collection filter F1 (F2, F3) from the downstream side in terms of the flow direction of the exhaust gas. Then, the PM collected therein is vaporized or burned. The gas generated at this time travels along the passage flow path L11 (L12, L13) together with the heating gas in the direction opposite to the flow direction of the exhaust gas, and a part of the passage flow path L11 (L12, L13). Through the analysis gas flow path L41 (L42, L43) that branches from the middle of the gas, the gas is introduced to the analysis unit 3 that performs gas analysis. The rest further travels through the passage flow path L11 (L12, L13) in the direction opposite to the flow direction of the exhaust gas, and merges with the exhaust gas at the branching point where the passage flow paths L11, L12, L13 branch into three. It flows into the passage channel L12 (L13, L11).

Since the fourth open / close valves V41, V42, and V43 are provided on the gas analysis channels L41, L42, and L43 branched from the passage channels L11, L12, and L13, the corresponding valves V41 (V42) are provided. , V43) only, and the generated gas needs to be introduced into the analysis unit 3. In addition, the gas analysis flow path is integrated into one, and the analysis gas flow rate control device 4 that controls the dryer 2, the analysis unit 3, and the flow rate Qm of the analysis gas on the integrated gas analysis flow path L 4. Are arranged in this order. The analysis unit 3 uses, for example, NDIR and calculates the mass (or concentration) of PM from the mass of CO ₂ and SO ₂ obtained by measuring the generated gas.

  A cooling state generation circuit for creating a cooling state includes a gas inflow port PI2 into which a cooling gas in a room temperature state is introduced, and three branches in the middle of the extension from the inflow port PI2, and each passage flow path L11, L12, Cooling gas flow paths L31, L32, L33 connected downstream of the collection filters F1, F2, F3 of L13 and upstream of the first on-off valves V11, V12, V13, and the respective cooling gas flows It consists of 3rd opening-and-closing valves V31, V32, and V33 provided in paths L31, L32, and L33, respectively. A cooling gas flow rate control means 12 is provided on the cooling gas flow path L3 before branching. This cooling gas flow rate control means 12 controls the flow rate Q2 of the cooling gas so that the inflow flow rate Qin of the exhaust gas becomes constant even if the flow rate Qall of the venturi 4 slightly varies.

  In such a configuration, when only one of the third open / close valves V31 (V32, V33) is opened, the cooling gas flows into the corresponding passage flow paths L11 (L12, L13), and the collection filter F1 (F2). F3) is blown from the downstream side in the direction of the exhaust gas flow. The cooling gas that has cooled the collection filter F1 (F2, F3) in this way further travels through the passage passage L11 (L12, L13) in the direction opposite to the flow direction of the exhaust gas, and the passage passage L11. , L12 and L13 join the exhaust gas and flow into the other passages L12 (L13 and L11).

  The flow rate control means 13 controls the Q3 so that the total flow rate, that is, the value of Qall-Q3 is constant even if the flow rate Qall of the venturi 4 slightly fluctuates due to temperature and absolute pressure ( The total flow rate Qall of the gas flowing into the constant flow meter 4 is Qin + Q1 + Q2 + Q3-Qm. If Qall-Q3 is kept constant, Q1 and Qm are constant, so Q2 is controlled as described above. To control Qin).

  As is apparent from the configuration of the heating state generation circuit and the cooling state generation circuit described above, in this embodiment, the heating gas passages L21, L22, L23 and the cooling gas passages L31, L32, L33 The inflow port PI2, which is the starting end portion of each, is made common, so that a common gas can be used as the heating gas and the cooling gas. Then, the flow path branches from the middle, and the gas flowing through the heating gas flow paths L21, L22, and L23 is heated to heating gas in the heating furnaces R1, R2, and R3, and becomes the heating gas, and the cooling gas flow paths L31, L32, What flows through L33 is configured to be the cooling gas as it is. The heating gas flow path and the cooling gas flow path may be provided separately and different gases may be used.

  As shown in FIG. 3, the state transition mechanism 6 is a dedicated or general-purpose computer composed of, for example, a CPU, a memory, an input / output channel, etc., and the CPU operates according to a program stored in the memory. A control signal is output to control opening / closing of the valves V11 to V43 in the fluid circuit.

  FIG. 4 is a timing chart of the opening / closing control of the specific valves V11 to V43, and FIGS.

  First, as shown in FIG. 5, when the first filter F1 is in the collection state, the second filter F2 is in the heating state and the third filter F3 is in the cooling state. By the next state transition, the first filter F1 is in the heating state, the second filter F2 is in the cooling state, and the third filter F3 is in the collecting state (see FIG. 6). Further, by the next state transition, the first filter F1 is in the cooling state, the second filter F2 is in the collecting state, and the third filter F3 is in the heating state (see FIG. 7). Then repeat this cycle.

  Therefore, when attention is paid to each filter F1 (F2, F3), the state transitions in the order of the collection state, the heating state, and the cooling state. On the other hand, the state phases of the filters F1, F2, and F3 are shifted from each other. In particular, when one filter finishes the collection state, the next filter is in the collection state with no free time.

  Therefore, with such a configuration, one of the filters F1 (F2, F3) is always in a collecting state, PM is not collected, and the three filters F1, F2, F3 Since the heating state, that is, the gas analysis state, is continued one after another, the measurement interval can be substantially shortened to 1/3 as compared with the conventional case of analyzing with one filter. Further, as described in the first embodiment, since the gas combustion time can be shortened by the characteristic configuration of the heating furnaces R1 to R3, the effect of further shortening the measurement time is also superimposed, and the time resolution is dramatically improved. Can be improved.

  Furthermore, with the fluid circuit having these three filters as a basic configuration, a plurality of fluid circuits are provided in parallel, and the phase in each fluid circuit is shifted, so that the sampling time is 1 / 6 (in the case of two fluid circuits), 1/9 (in the case of three fluid circuits)... Can be further shortened.

  In addition, since the filter combustion method is basically used, accuracy and reliability can be ensured in the mass measurement of PM, and the attachment / detachment of the filter, stabilization of the water content, or stabilization of the water content, as in the balance method. Since no large-scale equipment is required to make it easier, it can be mounted on a vehicle.

  When the present apparatus 100 is mounted on a vehicle, as described above, the time resolution of measurement can be greatly improved as compared with the conventional case. Therefore, PM emission in a situation where the engine 200 is dynamically operated, such as actual driving on the road. The time change of the quantity can be grasped in a state close to continuous measurement, which can contribute to the dynamic analysis of the engine 200 that could not be achieved in the past and the performance improvement thereby.

  The present invention is not limited to the above embodiment. For example, the fluid circuit configuration can be changed as appropriate, and the filter holding chamber holding the filter may be heated without using a heating furnace. As the state transition mechanism, not only a computer but also other electric control devices such as a sequencer may be used.

  In addition, the present invention can be variously modified without departing from the spirit of the present invention.

1 is a schematic longitudinal sectional view of a particulate matter measuring device according to a first embodiment of the present invention. The schematic diagram which shows the whole measurement system containing the particulate-material measuring apparatus in 2nd Embodiment of this invention. The fluid circuit diagram which shows the whole particulate matter measuring device in the embodiment. The timing chart which shows the valve opening / closing timing in the same embodiment. The fluid circuit diagram which shows each state of the particulate matter measuring device in the embodiment. The fluid circuit diagram which shows each state of the particulate matter measuring device in the embodiment. The fluid circuit diagram which shows each state of the particulate matter measuring device in the embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Particulate matter measuring device 200 ... Engine 200
3 ... analyzer 6 ... state transition mechanisms L11, L12, L13 ... passing passages L2, L21, L22, L23 ... heating gas passages L3, L31, L32, L33 ... cooling Gas flow paths F1, F2, F3 ... collection filters R1, R2, R3 ... heating furnace

Claims (4)

A heating furnace, a connecting pipe extending from the heating furnace, and a filter holding chamber connected to the tip of the connecting pipe are provided, and the heating gas that has been heated to the heating furnace passes through the connecting pipe. Then, it flows into the filter holding chamber, and is blown to the collection filter held therein, so that the particulate matter in the engine exhaust gas collected by the collection filter is vaporized or burned. And
The particulate matter measuring device in which the gas outlet portion of the heating furnace has a shape in which the inner diameter gradually decreases toward the tip, and the tip inner diameter is smaller than the inner diameter of the connection pipe.   The particulate matter measuring device according to claim 1, wherein a heat storage member that forms a plurality of agglomerates or integrates a plurality of agglomerates in an integrated manner is disposed in the internal flow path of the heating furnace.   The exhaust gas is guided to the filter holding chamber, and the particulate matter is collected by the filter. The heating gas is directed to the filter from a direction opposite to the exhaust gas passage direction. The particulate matter measuring device according to claim 1, wherein the particulate matter measuring device is configured to be sprayed. The temperature of the gas passing through the inside is increased, and the filter is heated by blowing the increased temperature gas to the filter in the filter holding chamber connected through the connection pipe,
A heating furnace in which the gas outlet portion has a shape in which the inner diameter gradually decreases toward the tip, and the tip inner diameter is smaller than the inner diameter of the connection pipe.