JP4855811B2 - Fine particle amount detection system - Google Patents

Description

  The present invention relates to a fine particle amount detection system. More specifically, the present invention relates to a fine particle amount detection system that detects the amount of fine particles deposited on a filter that collects fine particles in a gas.

  As a means for collecting fine particles in the gas and purifying the gas, filtration by a filter is typical. In these particulate collection filters, the clogging of the filter progresses as the particulates accumulate, and the filter performance deteriorates. Therefore, the filter itself is replaced or deposited before the amount of particulates reaches the filter usage limit. Regeneration treatment is necessary to remove the fine particles. In order to determine the timing of this replacement or regeneration process, it is necessary to predict the amount of particulate accumulation, and the amount of particulate accumulation is detected based on the differential pressure before and after the filter, the exhaust flow rate, the air-fuel ratio, and the like (for example, Patent Document 1). And Patent Document 2).

  In Patent Document 1, when the accelerator opening change rate is small and the exhaust gas flow rate is large, the amount of accumulated particulates is detected from the differential pressure between the inlet and outlet of the particulate collection filter and the exhaust gas flow rate. A technique for estimating the amount of particulate emission from the amount and the rotational speed of the engine is disclosed.

Patent Document 2 discloses a method for estimating a deposition amount of fine particles in which an air-fuel ratio of exhaust gas is detected and a generation amount of fine particles contained in the exhaust gas is calculated based on the air-fuel ratio.
JP 2004-19529 A JP 2006-2672 A

  However, in the method of detecting the differential pressure between the exhaust pressure before and after the filter, the pressure loss of the filter is often not uniquely determined with respect to the amount of accumulated particulate matter. Also, for example, in a wall flow type ceramic filter (DPF: Diesel particulate filter) that collects particulate matter (PM) of diesel engine, after collecting particulates at low temperature, When the temperature of the coated catalyst is temporarily raised to the activation temperature, the fine particles deposited in the pores are removed by oxidation, and the pressure loss is greatly reduced due to the slight disappearance of fine particles in the pores. However, it was difficult and difficult to adjust the playback system.

  Also, in the method of calculating the amount of particulate generation from the air-fuel ratio of the exhaust gas and integrating the amount to estimate the amount of particulate deposition, the amount of particulate particulate is estimated as all the particulate generation amount accumulates on the filter. There has been a risk that the frequency of regeneration processing will increase and the fuel efficiency will decrease.

  The present invention has been made in view of the above-described problems, and it is possible to detect the amount of particulates deposited on the filter by a simpler method, and to detect the amount of particulates so that it is possible to easily determine the timing of replacement and regeneration processing of the filter. Provide a system.

  The present invention provides the following fine particle amount detection system.

[1] A particulate collection filter (hereinafter also referred to as “DPF”) having one or more electrodes on the outer surface or inside, a coil connected in series to the electrodes, and a deposit on the particulate collection filter Detection means for detecting the amount of the fine particles by measuring a resonance frequency of a circuit including the fine particle collection filter and the coil, or by measuring an oscillation frequency, and the fine particles detected by the detection means A fine particle amount detection system (hereinafter, also referred to as “first invention”) having first output means for outputting the amount.

[ 2 ] Including at least three of the engine speed, fuel injection amount, fuel injection timing, exhaust gas temperature, exhaust oxygen concentration, intake air flow rate, exhaust throttle opening, EGR valve opening, and travel distance of the internal combustion engine First prediction means for predicting the amount of the particulates deposited on the particulate collection filter based on information and a certain parameter, the amount of particulates detected by the detection means, and the prediction predicted by the first prediction means The particulate quantity detection system according to [1 ], further comprising means for changing the parameter or the fuel injection quantity based on the particulate quantity.

[ 3 ] The fine particles according to [ 2], further including means for outputting a signal when a difference between the fine particle amount detected by the detection means and the fine particle amount predicted by the first prediction means exceeds a predetermined amount. Quantity detection system.

[ 4 ] Second detection means for predicting the amount of the particulates deposited on the particulate collection filter from information including the differential pressure at the inlet / outlet of the particulate collection filter , the flow rate and temperature of the exhaust gas, and detected by the detection means The fine particle amount detection system according to [1 ], further including means for outputting a signal when a difference between the fine particle amount and the fine particle amount predicted by the second prediction unit exceeds a predetermined amount.

[ 5 ] The fine particle amount detection system according to [1 ], wherein the detection unit uses impedance at two or more frequencies.

[ 6 ] The fine particle amount detection system according to any one of [1] to [ 5 ], wherein the fine particle amount detected by the detection unit is corrected based on a temperature of the fine particle collection filter .

[ 7 ] The fine particle amount detection system according to [ 6 ], wherein the fine particle amount detected by the detection unit is corrected when the temperature exceeds 300 ° C.

[8] particulate amount detecting system according to [6] or [7] wherein the temperature does not use the particulate amount detected by said detecting means when less than 100 ° C., or is corrected to zero.

[9] The particulate temperature of the trapping filter is below 300 ° C. 100 ° C. or higher, the microparticles according to any one of [1] to [5], wherein the particulate amount detected by said detection means is used without correction Quantity detection system.

  According to the fine particle amount detection system of the present invention, the amount of fine particles deposited on the filter can be detected by a simpler method than before, and it is possible to easily determine the time for replacement or regeneration processing of the filter.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a fine particle amount detection system of the present invention will be described in detail with reference to the drawings. However, the present invention is not construed as being limited thereto, and unless it departs from the scope of the present invention. However, various changes, modifications, and improvements can be added based on the knowledge of those skilled in the art.

  FIG. 1 is a schematic diagram showing an example of an embodiment of a fine particle amount detection system 100 (first invention) according to the present invention. In this example, electrodes 2 and 2 are installed at two locations on the outer surface of the DPF 1, and the coil 3 is connected in series between the electrodes 2 and 2. The detecting means 7 measures the impedance of the circuit including the DPF 1 and the coil 3 and detects the amount of fine particles in the DPF 1 from the measured value. The amount of fine particles is output as a signal from the first output means 8. The output signal is used, for example, as a regeneration process start signal for the DPF 1. At this time, the areas of the two electrodes may be equal or different, and the area ratio may be freely designed between 0.01 and 1, for example.

  In the present fine particle amount detection system 100, the capacitance in the DPF 1 can be detected by measuring the impedance of the circuit including the DPF 1 and the coil 3. Since the electrostatic capacitance changes corresponding to the amount of fine particles, the amount of fine particles can be calculated from the impedance by obtaining the relationship between the amount of fine particles and impedance in advance.

  In the present embodiment, the impedance of the circuit including the DPF 1 and the coil 3 suddenly becomes 0 under the resonance condition Lω = 1 / Cω (L: inductance, C: capacitance, ω: 2πf (f: frequency)). As the distance approaches, the change in impedance with respect to the change in the amount of deposited fine particles becomes sharper, and the amount of deposited fine particles can be detected with higher accuracy. The inductance value of the coil 3 may be set so as to satisfy the resonance condition at the target fine particle deposition amount. That is, the variable coil 3 whose inductance can be adjusted is used as the coil 3, and the value of the inductance is controlled in advance so that the impedance suddenly approaches 0 when the amount of fine particles deposited reaches a predetermined amount. .

  Next, an example of another embodiment of the present invention will be described. In this example, the resonance frequency of the circuit including the DPF 1 and the coil 3 is measured by the detection means 7 in FIG. 1, and the amount of fine particles in the DPF 1 is detected from the value. The amount of fine particles is output as a signal from the first output means 8. The output signal is used, for example, as a DPF 1 replacement or regeneration process start signal.

  In the present embodiment, the present particulate quantity detection system 100 can detect the capacitance in the DPF 1 by measuring the resonance frequency of the circuit including the DPF 1 and the coil 3. Since the capacitance changes corresponding to the amount of fine particles, the amount of fine particles can be calculated from the resonance frequency by obtaining in advance the relationship between the amount of fine particles and the resonance frequency.

In this embodiment, the impedance of the circuit including the DPF 1 and the coil 3 suddenly approaches 0 under the resonance condition Lω = 1 / Cω, and the resonance frequency at this time is approximately ω = (1 / LC) ^{1. / 2} . If the inductance value of the coil 3 is controlled in advance and set so as to satisfy the resonance condition at the target fine particle deposition amount and fixed, the electrostatic capacity C of the DPF 1 changes due to the fine particle deposition. The frequency ω also changes. By measuring the resonance frequency ω, the amount of deposited fine particles can be detected. Alternatively, by forming an oscillation circuit with a circuit including the DPF 1 and the coil 3 and measuring the oscillation frequency with a frequency counter or the like, the capacitance C may be calculated to detect the amount of deposited fine particles.

  FIG. 2 is a schematic diagram showing an example of an embodiment of the fine particle amount detection system 200 (second invention) of the present invention. In this example, electrodes 2 and 2 are installed at two locations on the outer peripheral surface of the DPF 1, and the coil 3 is connected in series between the electrodes 2 and 2. The detecting means 7 measures the impedance of the circuit including the DPF 1 and the coil 3 and detects the amount of fine particles in the DPF 1 from the measured value. When the amount of fine particles exceeds a predetermined amount set in advance, the second output means 9 outputs a signal for starting the regeneration of the DPF 1. The reproducing means 10 receives the signal and starts reproducing the DPF 1.

  In the present embodiment, the amount of fine particles can be calculated by measuring the impedance of a circuit including the DPF 1 and the coil 3 as in the case of the first invention described above. The regeneration of the DPF 1 is performed, for example, by injecting fuel during the exhaust stroke and / or by injecting the fuel with a fuel injection device installed in the exhaust pipe, so that unburned fuel is introduced into the DPF 1 and / or the DPF 1 upstream of the exhaust pipe. It is supplied to the installed oxidation catalyst and burns there. The particulates are oxidized and burned by the combustion heat of the fuel and removed from the DPF 1. It is also possible to regenerate the DPF 1 by raising the exhaust gas temperature with a fuel burner, an electric heater or the like installed in the exhaust pipe and oxidizing and burning the fine particles with the heat. It goes without saying that the signal for starting the regeneration of the DPF 1 output from the second output means 9 can also be used as a regeneration start signal for other regeneration methods.

  Next, an example of another embodiment of the present invention will be described. In this example, the resonance frequency of the circuit including the DPF 1 and the coil 3 is measured by the detection means 7 in FIG. 2, and the amount of fine particles in the DPF 1 is detected from the value. When the amount of fine particles exceeds a predetermined amount set in advance, the second output means 9 outputs a signal for starting the regeneration of the DPF 1. The reproducing means 10 receives the signal and starts reproducing the DPF 1.

  In the present embodiment, the amount of fine particles can be calculated by measuring the resonance frequency of the circuit including the DPF 1 and the variable coil 3 as in the case of the other embodiment of the first invention described above. .

In the first invention and the second invention, it is also possible to adjust resonance conditions by connecting capacitance, DC resistance, etc. in series or in parallel in the circuit in addition to such inductance.
Further, in the fine particle amount detection system 100 and / or 200 of the present invention, it is of course possible to install the electrodes 2 and 2 inside the DPF 1, for example, parallel plates at the radial center of the DPF 1 as shown in FIG. It is also possible to embed the electrodes 2 and 2 in a shape, or to embed the electrodes 2 and 2 in the shape of a parallel plate near the radially outer periphery of the DPF 1 as shown in FIG.

  FIG. 5 is a schematic diagram showing an example of an embodiment of the fine particle amount detection system 100 (first invention) in which the DPF 1 is the DPF unit 20 in the fine particle amount detection system 100 of FIG. Except that the DPF 1 is replaced with the DPF unit 20, the present embodiment is the same as the fine particle amount detection system 100 of FIG.

  An example of an embodiment of the DPF unit 20 will be described with reference to a schematic diagram shown in FIG. In this example, a wall flow type DPF 1 in which end faces of a honeycomb structure in which a plurality of cells serving as gas flow paths are defined by porous partition walls is alternately plugged in a staggered pattern is used as the filter body. The DPF 1 has a structure in which the DPF 1 is held in the cylindrical metal tube 5 through a cylindrical mat 6 that surrounds the outer periphery of the DPF 1. A cylindrical electrode 4 is embedded in the vicinity of the center of the cross section of the DPF 1, and the impedance between the electrode 4 and the metal tube 5 is measured.

  In this DPF unit 20, the basic principle of detecting the amount of collected fine particles is the same as that of the aforementioned DPF 1, but the DPF 1 is generally held in a state of being held inside the metal tube 5 via the mat 6. In many cases, the DPF unit 20 of the present invention uses the metal tube 5 as one electrode, and measures the impedance between the metal tube 5 and the electrode 4 provided on the filter 1. An impedance measurement circuit is configured. In other words, in the first invention, the DPF 1 includes the metal tube 5 outside thereof, and the metal tube 5 corresponds to an electrode.

  In the DPF unit 20, fine particles are deposited on the DPF 1 by measuring the impedance of a circuit including the electrode 4 installed in the DPF 1, the metal tube 5, and the coil 3 connected in series therebetween. It is possible to detect a change in capacitance between the electrode 4 and the metal tube 5 due to the above. Since the electrostatic capacitance between the electrode 4 and the metal tube 5 changes corresponding to the amount of fine particles in the DPF 1, the amount of fine particles deposited on the DPF 1 can be measured from the impedance measurement data. Specifically, the relationship between the mass of the deposited fine particles and the impedance is graphed in advance based on the actual measurement value, and by measuring the impedance, the amount of the fine particles deposited on the DPF 1 at the time of measurement is calculated. Can be measured.

  As another embodiment, a change in capacitance between the electrode 4 and the metal tube 5 can be detected. Since the electrostatic capacitance between the electrode 4 and the metal tube 5 changes corresponding to the amount of fine particles in the DPF 1, the amount of fine particles deposited on the DPF 1 can be measured from the measurement data of the resonance frequency. Specifically, the relationship between the mass of the deposited fine particles and the resonance frequency is graphed in advance based on the actual measurement value, etc., and by measuring the resonance frequency, the accumulated amount of the fine particles at the time of measurement is determined. Can be measured.

FIG. 6 is a schematic diagram showing an example of an embodiment of the fine particle amount detection system 200 (second invention) in which the DPF 1 is the DPF unit 20 in the fine particle amount detection system 200 of FIG. 2 is the same as the particle amount detection system 200 of FIG.
Also in the DPF 1 of FIG. 6, in the second invention, a metal tube 5 is provided outside, and the metal tube 5 corresponds to an electrode.

  In the DPF unit 20, it is preferable to provide the electrode provided in the vicinity of the center of the cross section of the DPF 1. For example, as shown in FIG. 7, a cylindrical electrode 4 is embedded inside the DPF 1 along the partition walls of the honeycomb structure. 8, the plate-like electrode 4 is embedded in the DPF 1 along the partition walls of the honeycomb structure, or a part of the plugging portion near the center of the end face is made of a conductive material as shown in FIG. It is also possible to form the electrode 4 by filling it.

  As a material of the mat 6 surrounding the outer peripheral portion of the DPF 1, a material in which fibers mainly composed of ceramics such as alumina and silica are formed into a mat shape can be suitably used. Furthermore, when the mat is made of a wire mesh made of a conductive material such as stainless steel instead of a non-conductive material such as ceramic, the mat also constitutes a part of the electrode. Moreover, as a material of the metal pipe body 5, a ferritic stainless steel etc. can be used conveniently.

  The form of DPF 1 is not particularly limited, but a wall flow type or a porous ceramic foam as exemplified in the above embodiment can be suitably used. The material of the filter is not particularly limited, but one or more ceramics selected from the group consisting of silicon carbide, cordierite, alumina titanate, sialon, mullite, silicon nitride, zirconium phosphate, zirconia, titania, alumina, and silica. Or what consists of the material which has a sintered metal as a main component is suitable.

  In the DPF 1 or the DPF unit 20 of the first invention and the second invention, the frequency of the alternating current when the resonance frequency is measured may be any frequency, but is preferably 1 kHz to 10 MHz. If the frequency is less than 1 kHz, the ratio of the direct current resistance component to the impedance increases, so the relative change rate of the resonance frequency due to the change in capacitance decreases, and the detection accuracy of the amount of deposited particulates decreases. On the other hand, if it exceeds 10 MHz, the amount of noise-like inductance (inductance generated outside the coil 3) included in the entire measurement system including the signal extraction line from the DPF 1 may be excessive, and measurement accuracy may be reduced. Needless to say, when the signal extraction line can be shortened, the frequency may be lower or higher (for example, 50 MHz).

In the first and second aspects of the invention, the engine speed, fuel injection amount, fuel injection timing, exhaust gas temperature, exhaust oxygen concentration, intake air flow rate, exhaust throttle opening, EGR valve opening, and travel distance of the internal combustion engine It is preferable to have first predicting means for predicting the amount of fine particles deposited in the DPF 1 based on information including at least three of them and parameters determined for the information. Then, by feeding back the detected amount of fine particles detected by the detecting means 7 to the first predicting means, the difference between the amount of fine particles predicted by the first predicting means and the amount of fine particles detected by the detecting means 7 or its change amount. Therefore, it is preferable to change the parameter for calculating the prediction amount by the first prediction means. Thereby, for example, the regeneration timing of the DPF 1 can be adjusted with higher accuracy.
Alternatively, it is preferable to change the control signal to the fuel injection system. As a result, an operation for reducing the amount of fine particles deposited on the DPF 1 becomes possible.
The exhaust gas temperature may be any of the inlet and outlet temperatures of the exhaust gas to the DPF 1, but the temperature of the DPF 1 inlet having a higher relationship with the fuel injection amount, that is, the combustion temperature is more preferable.

  If the difference between the amount of fine particles predicted by the first predicting means and the amount of fine particles detected by the detecting means 7 exceeds a predetermined amount, a failure of the DPF 1 or the engine is considered. For example, the difference between the amount of fine particles detected by the detection means 7 at a certain time and the amount of fine particles detected by the detection means 7 after a certain time from the certain time is predicted by the first prediction means. When the amount of fine particles deposited on the DPF 1 in a certain time is very small, it is considered that the DPF 1 is damaged. Therefore, in such a case, it is preferable to have means for outputting a signal such as an alarm signal for notifying the driver.

In the first invention and the second invention, there is provided a second predicting means for predicting the amount of fine particles deposited on the DPF 1 from information including the differential pressure between the exhaust gas inlet and outlet to the DPF 1 and the flow rate and temperature of the exhaust gas. When the difference from the detected amount of fine particles detected by the detecting means 7 exceeds a predetermined amount, it is preferable to have means for outputting a signal.
In such a case, for example, the end face inside the DPF 1 may be blocked by fine particles. Therefore, when it is determined that the end face is closed, it may be used as a signal for starting immediate regeneration or used as an alarm signal for notifying the driver. Used as a signal for storage for later analysis.
Even when the pressure difference between the exhaust gas inlet and the outlet of the DPF 1 is the same, the amount of fine particles deposited on the DPF 1 differs depending on the flow rate and temperature of the exhaust gas (the differential pressure increases as the flow rate increases), so the second predicting means , The amount of deposited fine particles on the DPF 1 is predicted from information including the flow rate and temperature of the exhaust gas.

  In the first invention and the second invention, in calculating the amount of fine particles detected by the detection means 7, it is preferable that the detection means 7 uses impedance at two or more frequencies. It is possible to pass a current having two or more frequencies to one electrode set provided in the DPF 1 or to pass a current having one or two or more frequencies to two or more electrode sets. Thus, the accuracy can be improved by calculating the detected particle amount based on the impedances at a plurality of frequencies. At this time, if two or more frequencies are different by a factor of 2 or more, more preferably 10 or 10 times between the lowest frequency and the highest frequency, the accuracy of measurement is further improved. To do.

  FIG. 13 is a graph showing changes in impedance with temperature. Although the impedance change is small until the temperature of the DPF 1 reaches 230 ° C., the impedance gradually decreases as the temperature further increases, and rapidly decreases when the temperature exceeds 300 ° C. Therefore, in the fine particle amount detection systems 100 and 200, it is preferable that the fine particle amount detected by the detecting means 7 is corrected according to the change in impedance. That is, it is preferable to have a correction unit that corrects the amount of fine particles detected by the detection unit 7 based on the temperature of the DPF 1. This temperature (DPF temperature) may be the DPF inlet temperature of the exhaust gas, or the average of the inlet temperature and the outlet temperature. Any temperature representative of DPF1 may be used.

FIG. 15 is a graph showing changes in impedance due to humidity. The impedance of the DPF 1 decreases as the humidity increases, and decreases significantly when the ratio exceeds 80% (relative humidity). For this reason, in the fine particle amount detection systems 100 and 200 according to the first and second inventions, it is preferable that the fine particle amount detected by the detecting means 7 is corrected according to the change in impedance. That is, it is preferable to have a correction unit that corrects the amount of fine particles detected by the detection unit 7 based on humidity.
For this reason, as one aspect, it is preferable to perform correction so that the amount of fine particles detected at a temperature of less than 100 ° C. at which impedance changes due to relative humidity is not used or zero. If the detected amount of fine particles is zero, for example, when the car has just started running, the second output means will give an error signal to start the regeneration process even though the amount of fine particles actually deposited is small. It is possible to avoid starting the reproduction process by outputting.

Furthermore, as another embodiment of the first invention and the second invention, when the temperature of the DPF 1 is 100 ° C. or higher and 300 ° C. or lower, it is not necessary to correct the amount of fine particles detected by the detecting means 7.
As a result, the amount of fine particles detected by the detection means in the temperature range of 100 ° C. or more and 300 ° C. or less, in which the change in impedance due to temperature and humidity is not large, can be used, for example, the regeneration timing of DPF 1 can be adjusted with higher accuracy .

Further, in order to prevent the amount of fine particles detected at temperatures below 100 ° C. and above 300 ° C. from being used, when the temperature of the DPF 1 is less than 100 ° C. or exceeds 300 ° C., the detecting means 7 The amount of detected fine particles can be set to zero, and correction can be made not to be performed at 100 ° C. or more and 300 ° C. or less.
Depending on the operating conditions of the internal combustion engine or the like in which the particulate quantity detection systems 100 and 200 of the present invention are used, a temperature range that is not preferably corrected is preferably 120 ° C. or higher and 230 ° C. or lower with less influence of impedance change due to temperature and humidity. It can also be.

  The particulate matter detection systems 100 and 200 according to the first and second inventions can be widely used for purifying gas containing particulates, and the use thereof is not limited, but the internal combustion engine such as a diesel engine or a gasoline engine is used. It can be particularly suitably used as the particulate quantity detection system 100, 200 deposited on the DPF 1 for collecting particulates in the exhaust. Further, the DPF 1 may be loaded with a catalyst component such as Pt (platinum) for the purpose of promoting the oxidation removal of the fine particles during the regeneration process.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

Example 1
Add 15 to 25% by mass of graphite as a pore-forming agent and 5 to 15% by mass of synthetic resin such as PET, PMA, and phenolic resin as a pore-forming material, and then add a predetermined amount of methylcellulose and a surfactant. Then, water was added to this and kneaded to make a clay. Next, this clay is vacuum degassed, extruded into a honeycomb structure, dried by microwave drying and hot air drying, and then fired at a maximum temperature of 1400 to 1435 ° C. ) Was manufactured.

  In order to make this honeycomb structure into a wall flow type filter, the end portions of the cells were alternately plugged in a staggered manner on both end faces of the honeycomb structure. Furthermore, Pt was supported, and a wall flow structure filter having a diameter of 144 mm and a length of 152 mm was obtained. By applying and baking silver (Ag) paste at two locations on the outer surface of the filter, electrodes 2 and 2 are formed as shown in FIG. 1, and the inductance of the coil 3 is adjusted to be zero and adjusted. A circuit for measuring the impedance between the electrodes 2 and 2 was constructed.

  Flowing diesel engine exhaust gas containing particulate matter through this filter and measuring the impedance between the electrodes 2 and 2 while depositing the particulate on the filter, the mass of the deposited particulate and the measured impedance The relationship is as shown in FIG. 10, and it was confirmed that the amount of deposited fine particles can be measured from the impedance value. The current frequency was 10 MHz.

  Next, using the filter manufactured above, the inductance value of the coil 3 was adjusted in advance so as to satisfy the resonance condition Lω = 1 / Cω when the deposited amount of fine particles was 5 g / liter (L). After the particulates in the filter were once completely oxidized and removed with an electric furnace, the exhaust gas of the diesel engine containing the particulates was passed through the filter, and the impedance between the electrodes was measured while the particulates were deposited on the filter. The relationship between the amount of deposited fine particles and the impedance is as shown in FIG. 11. When the amount of deposited fine particles reached 5 g / L, the impedance suddenly approached zero. From this result, it was possible to measure the amount of deposited fine particles in the DPF 1 by measuring impedance.

(Example 2)
As shown in FIG. 12, the logarithmic values of the relationship between the frequency and impedance at room temperature of the filter manufactured by the method of Example 1 are approximately inversely proportional.
As shown in FIG. 13, the relationship between the temperature of the filter and the impedance was small when the temperature of the filter was 300 ° C., but decreased sharply when the temperature exceeded 400 ° C. It can be seen that it is preferable to perform correction by temperature under conditions exceeding 300 ° C.

(Example 3)
FIG. 14 shows the relationship between frequency and impedance under different humidity, and FIG. 15 shows the relationship between humidity and impedance at room temperature. From FIG. 15, the impedance rapidly decreased when the humidity was 70% or more at a frequency of 10 MHz or less. This shows that it is preferable to perform correction based on humidity.

  The present invention can be suitably used as a particulate amount detection system used for collecting and purifying particulates in exhaust gas from internal combustion engines such as diesel engines and gasoline engines.

It is a schematic diagram which shows an example of embodiment of the fine particle amount detection system which concerns on this invention (1st invention). It is a schematic diagram which shows an example of embodiment of the fine particle amount detection system which concerns on this invention (2nd invention). In the particulate quantity detection system according to the present invention, it is a schematic diagram showing an example of electrode arrangement inside the DPF. FIG. 6 is a schematic diagram showing another example of electrode arrangement inside the DPF in the fine particle amount detection system according to the present invention. It is a schematic diagram which shows an example of embodiment of the fine particle amount detection system which concerns on this invention (1st invention). It is a schematic diagram which shows an example of embodiment of the fine particle amount detection system which concerns on this invention (2nd invention). It is a schematic diagram which shows an example of the form of the electrode of the DPF unit which concerns on this invention. It is a schematic diagram which shows the other example of the form of the electrode of the DPF unit which concerns on this invention. It is a schematic diagram which shows the further another example of the form of the electrode of the DPF unit which concerns on this invention. In Example 1, it is a graph which shows the relationship between the mass of the deposited fine particle, and impedance. In Example 1, it is a graph which shows the relationship between the mass of the deposited fine particle, and impedance. In Example 2, it is a graph which shows the relationship between a frequency and an impedance. In Example 2, it is a graph which shows the relationship between temperature and the change of an impedance. In Example 3, it is a graph which shows the relationship between a frequency and an impedance. In Example 3, it is a graph which shows the relationship between humidity and an impedance.

Explanation of symbols

1: particulate collection filter (DPF), 2: electrode, 3: coil, 4: electrode, 5: metal tube, 6: mat, 7: detection means, 8: first output means, 9: second output means 10: regeneration means, 20: particulate collection filter unit (DPF unit), 100, 200: particulate quantity detection system.

Claims (9)

A particulate collection filter comprising one or more electrodes on the outer surface or inside;
A coil connected in series to the electrode;
Detection means for detecting the amount of fine particles deposited on the fine particle collection filter by measuring a resonance frequency of a circuit including the fine particle collection filter and the coil, or by measuring an oscillation frequency ;
A fine particle amount detection system comprising: a first output unit that outputs the fine particle amount detected by the detection unit. Information including at least three or more of the engine speed, fuel injection amount, fuel injection timing, exhaust gas temperature, exhaust oxygen concentration, intake air flow rate, exhaust throttle opening, EGR valve opening, and travel distance of the internal combustion engine is constant. First prediction means for predicting the amount of the particulates deposited on the particulate collection filter based on the parameters of
According to claim 1 and a means for changing the control signal to the parameter or the fuel injection system based on said quantity of particulate which is predicted by the quantity of particulate and the first prediction means detected by said detecting means Fine particle amount detection system. The fine particle amount detection system according to claim 2 , further comprising means for outputting a signal when a difference between the fine particle amount detected by the detection unit and the fine particle amount predicted by the first prediction unit exceeds a predetermined amount. Second prediction means for predicting the amount of the particulates deposited on the particulate collection filter from information including the differential pressure at the entrance and exit of the particulate collection filter and the flow rate and temperature of the exhaust gas;
2. The particulate quantity detection system according to claim 1, further comprising means for outputting a signal when a difference between the particulate quantity detected by the detection means and the particulate quantity predicted by the second prediction means exceeds a predetermined amount. . The fine particle amount detection system according to claim 1, wherein the detection unit uses impedance at two or more frequencies. Particulate amount detecting system according to any one of claims 1 to 5, wherein the particulate amount is corrected based on the temperature of the particulate collection filter detected by said detecting means. The fine particle amount detection system according to claim 6 , wherein when the temperature exceeds 300 ° C., the fine particle amount detected by the detection unit is corrected. 8. The fine particle amount detection system according to claim 6 , wherein the fine particle amount detected by the detection means when the temperature is lower than 100 ° C. is not used or is corrected to zero. The particulate temperature of the trapping filter is below 300 ° C. 100 ° C. or higher, the amount of particulates detection system according to any one of claims 1 to 5, wherein the particulate amount detected by said detection means is used without correction.

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