JP2016053341A - Exhaust emission control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device capable of restricting the reaction residual quantity of particulate matters(PM) in a case of oxidation of the PM captured by a filter body by applying heat treatment using electromagnetic waves.SOLUTION: An exhaust emission control device of an embodiment comprises: a filter body capturing particulate matters contained in exhaust gas; an electrically conductive outer container for accommodating the filter body; an electromagnetic wave generation part for generating electromagnetic waves with variable frequency; and a frequency control part for variably controlling the frequency of the electromagnetic waves generated in the electromagnetic wave generation part within a predetermined bandwidth, in which the exhaust emission control device is configured such that the particulate matters adhered to the filter body are heated directly or indirectly by irradiating the filter body with the electromagnetic waves. The frequency control part has a function of time varying the propagation mode of the electromagnetic waves generated in the interior of the outer container in the filter body so as to straddle the frequency for generating a single mode and the frequency for generating a multiple mode.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an exhaust emission control device.

  For example, exhaust gas discharged from an internal combustion engine such as a diesel engine, a thermal power plant, an oil boiler, or the like contains particulate matter (PM: particulate matter) mainly composed of carbon particles. Since PM is an environmental pollutant, for example, exhaust gas discharged from an internal combustion engine is discharged to the outside air through an exhaust purification device to which a trap filter is applied as a filter body for capturing PM. A trap filter used in an exhaust purification device is generally made of porous ceramics having excellent heat resistance, and such a trap filter is called a DPF (diesel particulate filter). .

  When the amount of PM collected by the DPF exceeds the allowable value, clogging occurs, the exhaust gas pressure increases, and the fuel consumption of the internal combustion engine deteriorates. For this reason, it is necessary to recover the PM collection capability by performing regeneration processing (processing for recovering the PM collection capability) on the DPF at an appropriate time. As a regeneration process, a process is known in which PM adhering to the DPF is heated to an oxidation reaction temperature (for example, 600 ° C. or more) and burned by injecting extra fuel to the DPF to remove the PM. . However, in such an oxidation reaction process, the fuel and PM are mixed and combusted, so that the temperature may increase excessively, and the DPF may be damaged, so that replacement may be necessary. In addition, when fuel is injected, the wall of the exhaust pipe other than the DPF is also heated, so that the use of extra fuel increases energy loss.

  In order to prevent such a problem, for example, as disclosed in Patent Documents 1 to 3, heating the filter by irradiating electromagnetic waves instead of fuel injection makes it easier to control the temperature of the DPF and efficiently heat the filter. Is possible.

  However, when radiating electromagnetic waves into the exhaust pipe in which the DPF is accommodated, the electric field strength is lower in the vicinity of the grounded pipe wall than in the central part of the exhaust pipe, so the temperature in the vicinity of the pipe wall is relatively low. . Furthermore, since the porous ceramic has a low thermal conductivity, a high temperature region and a low temperature region are generated inside the DPF. As a result, there is a problem that PM trapped particularly in the low temperature region of the DPF is not burned off and the regeneration process is not performed well.

  The reason for this is that, in the case of a method called single mode (fundamental mode) where the frequency is the lowest when electromagnetic waves propagate in the exhaust pipe, the electric field strength or magnetic field strength in the vicinity of the pipe wall is low, so the temperature here This is because it becomes low. The single mode is, for example, a TE10 mode in a square tube or a TE11 mode in a circular tube. Since the high temperature portion where the electric field strength is high and the temperature is high does not occur in the vicinity of the pipe wall of the exhaust pipe, the temperature in the vicinity of the pipe wall is low.

  Further, as described in Patent Documents 1 and 2, when a DPF is heated using a cavity resonator, a standing wave is generated, so that a low temperature region is similarly generated in the traveling direction. Since the electromagnetic wave is reflected by the reflector and forms a standing wave, the position of the high temperature portion does not move. For this reason, a low temperature part also arises with respect to the traveling direction. As a countermeasure against this, it is mentioned as an example that the position of the standing wave is moved by moving the reflector as in Patent Document 1, but since PM combustion is performed in a high temperature region of 600 ° C. or higher, There is a problem that it is difficult to operate the movable wall smoothly while maintaining durability.

Japanese Patent No. 5163695 Japanese Patent Application No. 2006-140063 Japanese Patent No. 5282727

  The embodiment provides an exhaust emission control device that can suppress the remaining amount of PM when applying heat treatment using electromagnetic waves to particulate matter (PM) collected in a filter body to oxidize the particulate matter (PM). Objective.

  An exhaust emission control device according to an embodiment includes a filter main body that captures particulate matter contained in exhaust gas, a conductive outer container that accommodates the filter main body, an electromagnetic wave generator that generates an electromagnetic wave having a variable frequency, A frequency control unit that variably controls the frequency of the electromagnetic wave generated in the electromagnetic wave generator within a predetermined band, and the electromagnetic wave is applied to the filter body, thereby directly or indirectly An exhaust emission control device configured to heat the particulate matter adhering to a filter body. The frequency control unit has a function of changing a propagation mode of the electromagnetic wave generated inside the outer container with time so as to cross a frequency for generating a single mode and a frequency for generating a multimode in the filter body. .

It is a conceptual diagram which shows the exhaust gas purification system containing the exhaust gas purification apparatus which concerns on this embodiment. It is a figure which shows an example of the specific structure of the exhaust gas purification apparatus which concerns on this embodiment applied to the exhaust gas purification system of FIG. It is a figure which shows another example of the specific structure of the exhaust gas purification apparatus which concerns on this embodiment applied to the exhaust gas purification system of FIG. It is a perspective view which shows typically the principal part of the exhaust gas purification apparatus shown in FIG. 2, Comprising: It is a figure which shows the structure at the time of using a circular cylinder. It is a perspective view which shows typically the principal part of the exhaust gas purification apparatus shown in FIG. 2, Comprising: It is a figure which shows the structure at the time of using a square cylinder. It is principal part sectional drawing of PM deposition process part of the exhaust gas purification apparatus which concerns on this embodiment. FIG. 2 is an explanatory diagram of single-mode and multi-mode frequencies, where FIG. 1A is an explanatory diagram of single-mode frequencies, and FIG. 1B is an explanatory diagram of multi-mode frequencies. It is the figure which showed the example of the time-dependent change of switching between each mode of a frequency variable control part. It is the figure which showed the other example of the time-dependent change of switching between each mode of a frequency variable control part. It is the figure which showed an example of the operation | movement algorithm of a frequency variable control part, Comprising: The example controlled so that the frequency of electromagnetic waves changes with the frequency pattern shown in FIG. It is the figure which showed another example of the operation | movement algorithm of a frequency variable control part, Comprising: The example controlled to change the frequency of electromagnetic waves with the frequency pattern shown in FIG. 8 is shown. It is a figure which shows typically the intensity distribution of the electromagnetic wave inside a filter main body at the time of irradiating the electromagnetic wave of a single mode oscillation frequency with respect to the filter main body of the exhaust gas purification apparatus shown in FIG. FIG. 3 is a diagram schematically showing the intensity distribution of electromagnetic waves inside the filter body when the filter body of the exhaust gas purification apparatus shown in FIG. 2 is irradiated with electromagnetic waves having a multimode oscillation frequency. It is a figure in the case where electromagnetic waves propagate in a single mode and electromagnetic waves propagate in a multimode inside the filter body. FIG. 3 is a diagram schematically showing the intensity distribution of electromagnetic waves inside the filter body when the filter body of the exhaust gas purification apparatus shown in FIG. 2 is irradiated with electromagnetic waves having a multimode oscillation frequency. It is a figure in the case where electromagnetic waves propagate in multimode and electromagnetic waves propagate in multimode inside the filter body. It is a figure which shows typically the intensity distribution of the electromagnetic wave inside a filter main body at the time of irradiating the electromagnetic wave of a single mode oscillation frequency with respect to the filter main body of the exhaust gas purification apparatus shown in FIG. FIG. 4 is a diagram schematically showing the electromagnetic wave intensity distribution inside the filter body when the filter body of the exhaust gas purification apparatus shown in FIG. 3 is irradiated with electromagnetic waves having a multimode oscillation frequency. It is a figure in the case where electromagnetic waves propagate in a single mode and electromagnetic waves propagate in a multimode inside the filter body. FIG. 4 is a diagram schematically showing the electromagnetic wave intensity distribution inside the filter body when the filter body of the exhaust gas purification apparatus shown in FIG. 3 is irradiated with electromagnetic waves having a multimode oscillation frequency. It is a figure in the case where electromagnetic waves propagate in multimode and electromagnetic waves propagate in multimode inside the filter body. It is a figure which shows an example of the specific structure of the exhaust gas purification apparatus which concerns on the 1st modification of this embodiment. It is the figure which showed an example of the operation algorithm of the frequency variable control part in the exhaust gas purification apparatus which concerns on the 1st modification of this embodiment, Comprising: The example controlled so that the frequency of electromagnetic waves changes with the frequency pattern shown in FIG. Indicates. It is a figure which shows an example of the specific structure of the exhaust gas purification apparatus which concerns on the 2nd modification of this embodiment. It is a figure which shows an example of a structure of the electromagnetic wave generator applied to the exhaust gas purification apparatus shown in FIG.

  FIG. 1 is a conceptual diagram showing an exhaust purification system including an exhaust purification device according to the present embodiment. As shown in FIG. 1, in the exhaust purification system according to this embodiment, exhaust gas 2 discharged from an internal combustion engine 1 such as a diesel engine is guided to an exhaust purification device 10. The exhaust emission control devices 10, 10 ′, 30, and 40 arrange PM (particulate matter) mainly composed of carbon particles as the particulate matter contained in the exhaust gas 2 in the particulate matter (PM) deposition processing unit 11. The exhaust gas 2 captured by using the filter main body 12 and from which PM has been removed is discharged to the outside air. In such exhaust purification apparatuses 10, 10 ′, 30, 40, PM trapped by the filter body 12 is heated and removed by the electromagnetic wave 14 generated from the electromagnetic wave generator 13, and thus the filter body 12 Playback processing is executed. Hereinafter, the exhaust emission control devices 10, 10 ′, 30, and 40 applied to such a system will be described in detail with reference to the drawings.

  FIG. 2 is a diagram showing an example of a specific configuration of the exhaust purification apparatus 10 according to the present embodiment applied to the above-described exhaust purification system. In FIG. 2, reference numeral 15a denotes a quartz plate that allows the electromagnetic wave 14 to pass therethrough and blocks the exhaust gas 2, and 16a denotes a conductor wall having a hole that blocks the electromagnetic wave and allows the exhaust gas to pass therethrough. As a result, the electromagnetic wave 14 and the exhaust gas 2 flow toward the filter body 12 through the cylindrical body 17 that is the same exhaust pipe. PM is collected and oxidized by the filter body 12, and the purified exhaust gas 2 is output to the opposite side of the cylindrical body 17. On the output side, the exhaust gas 2 and the electromagnetic wave 14 are separated by the perforated conductor wall 16b and the quartz plate 15b similar to the input side, and the electromagnetic wave 14 attenuated after passing through the filter body 12 is absorbed by the terminator 18.

A temperature sensor 21 may be disposed near the filter body 12. The temperature of the filter body 12 is measured and transmitted to the electromagnetic wave generator 13. The configuration of the temperature sensor 21 is generally a direct measurement such as a thermistor or a thermocouple, but may be an indirect measurement using an infrared detector or the like. (This includes not only measuring the temperature of the filter body directly but also measuring the ambient temperature or PM temperature.)
FIG. 3 is a diagram showing an example of another specific configuration of the exhaust purification device 10 ′ according to the present embodiment applied to the above-described exhaust purification system. A perforated conductor wall 16b is provided on the output side of the cylindrical body 17 '. A cavity resonator 19 is formed between the perforated conductor walls 16a and 16b, and a standing wave is generated in the cavity resonator 19 when the electromagnetic wave 14 is input thereto. Such a configuration may be used.

  In FIG. 3, the temperature sensor 21 is also arranged, but the temperature sensor 21 is not necessarily required.

  4 and 5 are perspective views schematically showing main parts of the exhaust emission control device 10 shown in FIG. The cylinder 17 of the exhaust emission control device 10 may be a circular cylinder 17c as shown in FIG. 4, or may be a square cylinder 17s as shown in FIG. In the case of the circular cylinder 17c, for example, a TE11 wave propagates in the cylinder 17c as a single mode, and in the case of the square cylinder 17s, a TE10 wave propagates in the cylinder 17s as a single mode. The filter 12 is generally circular or square in accordance with the cross section in the cylinders 17c and 17s, but does not necessarily match the cross-sectional shape of the cylinder, and even if there is a square filter in the circular cylinder. And vice versa, the action of the electromagnetic wave 14 is the same.

  3 is not shown in the perspective view of the main part of the exhaust purification apparatus 10 ′ shown in FIG. 3, but has the same configuration as that shown in FIG. Indicates.

  FIG. 6 is a cross-sectional view of the main part of the PM deposition processing unit 11 of the exhaust gas purification apparatus 10 shown in FIG. The PM deposition processing unit 11 includes a cylindrical body 17 serving as a flow path for the exhaust gas 2, a filter main body 12 disposed inside the cylindrical body 17, and an electromagnetic wave generator 13.

  The cylindrical body 17 is a conductive outer container made of metal having a cylindrical tube shape whose both ends are open ends and whose inner diameter is constant regardless of location. The cylindrical body 17 only needs to have a structure capable of discharging the exhaust gas 2 flowing in from the inflow end portion which is one opening end from the discharge end portion which is the other opening end. It may be made of a rectangular tube-shaped metal. Further, the inner diameter R of the cylindrical body 17 may be different for each place.

  Inside the cylindrical body 17 is disposed a filter body 12 that captures, for example, PM (particulate matter) mainly composed of carbon particles as a particulate matter contained in the exhaust gas 2. The filter body 12 is disposed so as to separate the internal space Vin on the inflow end portion side and the internal space Vout on the discharge end portion side of the tubular body 17 by filling a partial region inside the tubular body 17. .

  The filter body 12 is a trap filter formed of a porous body having a plurality of exhaust passages partitioned by partition walls, and is, for example, a DPF (diesel particulate filter). Examples of the porous body include silicon carbide (SiC) and cordierite which are porous ceramics.

  Next, the electromagnetic wave generator 13 generates an electromagnetic wave 14 (for example, a microwave) in a desired frequency band, and propagates the generated electromagnetic wave 14 from the entire inflow end portion of the cylindrical body 17 to the inside of the cylindrical body 17. The filter body 12 is irradiated. Thus, the filter main body 12 is heated by being irradiated with the electromagnetic wave 14.

  The electromagnetic wave generator 13 is connected to a frequency variable control unit 20 that variably controls the frequency of the generated electromagnetic wave 14. The frequency variable control unit 20 continuously changes the frequency of the electromagnetic wave 14 generated from the electromagnetic wave generator 13 within a predetermined frequency band including a boundary frequency between the single mode oscillation frequency and the multimode oscillation frequency.

  As shown in FIG. 4, when the cylindrical body 17 is a circular cylindrical body 17c, the single mode is a TE11 wave, and as shown in FIG. 5, when the cylindrical body 17 is a rectangular cylindrical body 17s, Single mode is TE10 wave. The single mode has the lowest cutoff frequency, and the multi mode has a higher cutoff frequency. When the filter main body 12 is in the cylinders 17c and 17s, the material of the filter main body 12 generally shows a value higher than the relative dielectric constant in vacuum. In comparison, the cut-off frequency is generally low even if the cylinders have the same size.

  FIG. 7 is an explanatory diagram of single-mode and multi-mode frequencies. FIG. 4A is an explanatory diagram of a single-mode frequency, and FIG. 4B is an explanatory diagram of a multi-mode frequency. In FIG. 7A, f1 indicates a single mode frequency, and in FIG. 7B, f2 indicates a multimode frequency. Moreover, in both figures, fb shows the frequency used as a boundary. As is apparent from FIG. 7, f1, f2, and fb always have a relationship of f1 <fb <f2, and fb corresponds to a multimode cutoff frequency.

  FIG. 8 and FIG. 9 are diagrams showing examples of changes over time of switching between the modes of the frequency variable control unit 20. As shown in FIG. 8, the frequency f1 is oscillated until the elapsed time t1, and the frequency f2 is oscillated from the elapsed time t1 to (t1 + t2). These f1 and f2 correspond to f1 and f2 in FIG. 7, respectively.

  As shown in FIG. 9, the change in frequency may be continuous instead of intermittent. In addition, the frequency is not limited to a uniform frequency increase / decrease, but includes a case where the frequency changes randomly or changes intermittently or discontinuously.

  FIG. 10 is a diagram illustrating an example of an operation algorithm of the frequency variable control unit 20. The operation algorithm shown in FIG. 10 is an example when the temperature sensor 21 is not used. For example, an example of control with a frequency pattern as shown in FIG. 8 is shown.

  After the operation is started, the frequency f1 is selected (S101), and the frequency is set (S102). Next, an output instruction is given to the electromagnetic wave generator 13 to turn on the output (S103), and a timer (not explicitly shown in FIG. 2) is started (S104). Thereby, the electromagnetic wave 14 is sent to the filter main body 12 and heating is started.

  After the filter body 12 is continuously heated to the timer T1 (S105), the electromagnetic wave generator 13 is instructed to turn off the output (S106), the frequency f2 is selected (S107), and the frequency is set again (S108). Next, an output instruction is given to the electromagnetic wave generator 13 to turn on the output (S109). After heating the filter main body 12 until the timer T2 (S110), an instruction to turn off the output is given to the electromagnetic wave generator 13 (S111). An end notification is made (S112) and an end process is performed.

  Furthermore, another modification will be described with reference to FIG. FIG. 11 is a diagram illustrating an example of an operation algorithm using the temperature sensor 21.

  After the operation starts, the operation from the selection of the frequency f1 (S201) to the start of the timer (S204) (S201 to S204) is performed in the same manner as S101 to S104 in FIG.

  Using the temperature sensor 21 (FIGS. 2 and 3), the temperature of the filter body 12 (including not only the filter directly, but also the case where the ambient temperature or PM temperature is measured) is measured, and the temperature obtained by the measurement is It is determined whether or not a specified temperature (for example, PM combustion start temperature) has been reached within the startup limit time (S205 and S206), and the temperature of the filter body 12 does not reach the specified temperature within the startup limit time (S206). Yes), it is determined that the system is abnormal, and system abnormality processing is performed. In other words, the output OFF is instructed to the electromagnetic wave generator 13 (S207), and an alarm is notified (S208).

If the temperature has risen normally (Yes in S205), the timer is reset (S209) and heating is continued until the specified time T1, but the temperature rises excessively in the filter body 12 and temperature runaway occurs. When the critical temperature limit H _Limit is exceeded (Yes in S210), system abnormality processing is immediately performed (S207 and S208).

  When the timer T1 can be normally continued (Yes in S211), the output from the electromagnetic wave generator 13 is turned off and the timer is reset (S212). The frequency is changed to f2 and the time is read as T2. (S213) The same process is performed again.

  If this is completed normally, an end notification is made (S214), and normal end processing is performed. Thereby, it is possible to realize a more effective filter regeneration process by changing the frequency.

  As described above, the frequency variable control unit 20 changes the frequency of the electromagnetic wave 14 generated from the electromagnetic wave generator 13 over time within a predetermined frequency band including the boundary frequency fb between the single mode oscillation frequency and the multimode oscillation frequency. Change.

  When the frequency of the electromagnetic wave 14 generated from the electromagnetic wave generator 13 is changed with time in the frequency band, the electromagnetic wave 14 having a single mode oscillation frequency is irradiated to the filter body 12 in a certain time zone, and in another certain time zone. The filter body 12 is irradiated with an electromagnetic wave 14 having a multimode oscillation frequency. As a result, the intensity distribution of the electromagnetic wave 14 inside the filter main body 12 can be significantly changed over time. In the following, this point will be described in more detail by taking the configuration of FIG. 2 as an example. As described so far, the cut-off frequency of each mode differs between the place where the filter main body 12 is present and the place where the filter main body 12 is not present. Therefore, the following description is based on the mode of the filter main body 12 portion.

  FIG. 12 is a diagram schematically showing the intensity distribution of the electromagnetic wave 14 inside the filter body 12 when the electromagnetic wave 14 having a single mode oscillation frequency is irradiated on the filter body 12. FIGS. 13 and 14 are diagrams schematically showing the intensity distribution of the electromagnetic wave 14 inside the filter body 12 when the electromagnetic wave 14 having the multimode oscillation frequency is irradiated onto the filter body 12. FIG. 13 shows a case where the electromagnetic wave 14 propagates in a single mode outside the filter body 12, and FIG. 14 shows that the electromagnetic wave 14 is also outside the filter body 12 compared to FIG. This shows the case of propagation in multimode.

  When the filter body 12 is irradiated with the electromagnetic wave 14 having a single mode oscillation frequency, the region Ss where the intensity of the electromagnetic wave 14 is strong is periodically in the direction along the axis of the cylindrical body 17 as shown in FIG. Distributed. Since this region Ss moves to the output side over time, the central portion of the filter body 12 becomes hot, but the region near the cylindrical body 17 always has a low intensity of the electromagnetic wave 14 and remains at a low temperature. is there.

  However, when the filter body 12 is irradiated with the electromagnetic wave 14 having the multimode oscillation frequency, the region Sm where the intensity of the electromagnetic wave is strong is in a direction perpendicular to the axis of the cylindrical body 17 as shown in FIG. However, it will be distributed periodically and will change significantly compared with the intensity distribution of the electromagnetic wave 14 shown in FIG. For this reason, a region where the intensity of the electromagnetic wave 14 is increased is also generated in the vicinity of the cylindrical body 17, resulting in a high temperature. On the other hand, a low temperature region is also generated at the center of the filter body 12, but since the temperature has already reached a high temperature in the single mode, there is no problem even if the temperature is low in the multi mode.

  FIG. 15 is a diagram schematically showing the intensity distribution of the electromagnetic wave 14 inside the filter body 12 corresponding to FIG. 3 when the filter body 12 is irradiated with the electromagnetic wave 14 having a single mode oscillation frequency. FIGS. 16 and 17 are diagrams schematically showing the intensity distribution of the electromagnetic wave 14 inside the filter body 12 corresponding to FIG. 3 when the filter body 12 is irradiated with the electromagnetic wave 14 having the multimode oscillation frequency. FIG. 16 shows a case where the electromagnetic wave 14 propagates in a single mode outside the filter body 12, and FIG. 17 shows that the electromagnetic wave 14 is also outside the filter body 12 compared to FIG. This shows the case of propagation in multimode.

  When the filter body 12 is irradiated with the electromagnetic wave 14 having a single mode oscillation frequency, as shown in FIG. 15, the region Ss where the intensity of the electromagnetic wave 14 is strong is periodic with respect to the direction along the axis of the cylindrical body 17 ′. However, in FIG. 15, the electromagnetic wave 14 is reflected by the conductor wall 16 b and a standing wave is generated, so that the position of Ss does not change when the frequency is not changed with time. For this reason, the intensity | strength of the electromagnetic waves 14 is low and the low temperature part arises also in the direction of the axis | shaft of cylinder 17 '. If the frequency of the electromagnetic wave 14 is changed within the range of the single mode oscillation frequency, the region Ss where the intensity of the electromagnetic wave 14 is strong changes the interval with respect to the direction along the axis of the cylindrical body 17 ′. The distribution changes in the axial direction, and the portion that was low temperature also changes to high temperature. However, the intensity of the electromagnetic wave 14 remains low in the vicinity of the cylindrical body 17 'as compared with the central portion, so that a low temperature portion remains.

  However, when the filter body 12 is irradiated with the electromagnetic wave 14 having the multimode oscillation frequency, as shown in FIG. 16 or FIG. 17, the region Sm where the intensity of the electromagnetic wave 14 is strong is a direction perpendicular to the axis of the cylindrical body 17 ′. In contrast, the intensity distribution of the electromagnetic wave 14 shown in FIG. 15 changes significantly. For this reason, a region where the intensity of the electromagnetic wave 14 is increased is also generated in the vicinity of the cylindrical body 17 ′, resulting in a high temperature. On the other hand, a low temperature region is also generated at the center of the filter body 12, but since the temperature has already reached a high temperature in the single mode, there is no problem even if the temperature is low in the multi mode.

  As described above, when the filter body 12 is irradiated with the electromagnetic wave 14 having the single-mode oscillation frequency and when the filter body 12 is irradiated with the electromagnetic wave 14 having the multi-mode oscillation frequency, the intensity distribution of the electromagnetic wave 14 inside the filter body 12. Is significantly different. Therefore, when the frequency of the electromagnetic wave 14 generated from the electromagnetic wave generator 13 is changed with time in a predetermined frequency band including the boundary frequency fb between the single mode oscillation frequency and the multimode oscillation frequency, the electromagnetic wave in the filter body 12 is changed. The intensity distribution of 14 also changes significantly with time. As a result, the temperature at each position in the filter body 12 is made uniform by changing the frequency in a short time, and the occurrence of a temperature difference is suppressed. Alternatively, even if the frequency is not changed frequently, only the high temperature part is reacted, and then the frequency is changed and the remaining part is heated to suppress the total remaining reaction amount. effective.

  The PM captured by the filter body 12 is burned and removed by irradiating the filter body 12 with the electromagnetic wave 14 and heating the filter body 12, and thus the regeneration process is performed on the filter body 12. .

  The operations and effects of the present embodiment described above are not particularly limited in the frequency range, but the frequency resources are actually limited, and there are various legal and technical restrictions in practice. Not too long. Hereinafter, in consideration of this, a method of using a frequency for further enhancing the effect will be described with reference to FIG. 7 again.

  As described in the above embodiment, the center frequency of the single mode frequency f1 and the multimode frequency f2 is (f1 + f2) / 2, and the bandwidth is (f2−f1). Since the frequency fb serving as the boundary between the single mode and the multimode only needs to be between f1 and f2, the narrower the distance between f2 and f1, the narrower the frequency used by the exhaust gas purification devices 10, 10 'becomes. Use efficiency goes up. In general, “bandwidth” ÷ “center frequency” is called a specific band, but when considering a frequency of 30 GHz or less suitable for heating, this is approximately 10% from the effective use of frequency and the frequency allocation width for each purpose. The following is desirable.

  Furthermore, in the case of assuming a use such as a portable type or an in-vehicle device, it is necessary to operate in a frequency band of 902 MHz to 928 MHz, 2400 MHz to 2500 MHz, and 5725 MHz to 5875 MHz, which is called an ISM band (Industry, Science and Medical). It is more practical due to the ease of licensing and the like.

  In addition, since it is not necessary that the frequency between f1 and f2 is continuous, for example, even when the operation is performed at two points of 2400 MHz and 2500 MHz, or at three points of 920 MHz, 2450 MHz, and 5800 MHz, etc. The operation is equivalent.

  As a modification of the embodiment, a mode in which a function of controlling the output or phase of the electromagnetic wave 14 irradiated to the filter body 12 by monitoring the intensity of the electromagnetic wave 14 emitted to the filter body 12 will be described below. To do.

<First Modification>
FIG. 18 is a diagram illustrating an example of a configuration of an exhaust purification device 30 according to a first modification of the embodiment. The exhaust purification device 30 shown in FIG. 17 has a configuration in which a bidirectional coupler 31, a phase control unit 32, and a determination unit 33 are further added to the configuration of the exhaust purification device 10 shown in FIG.

  The phase control unit 32 includes a stub 34 and a driving motor 35. The phase control unit 32 controls the phase by inserting a rod (stub 34) such as a metal or a dielectric into the cylindrical body 17. Match between the impedance on the side and the impedance on the signal source side.

  From the bidirectional coupler 31 as a power monitor, the monitor value of the traveling / reflected power is measured. From the temperature sensor 21, the temperature of the filter body 12 (direct measurement by the temperature sensor 21 or indirect measurement such as infrared detection) Monitor).

  The measured value is sent to the determination unit 33, and an instruction signal is transmitted from the determination unit 33 to each unit so that the temperature of the filter main body 12 becomes appropriate. For example, the instruction signal transmits a frequency instruction to the frequency variable control unit 20, an output instruction to the electromagnetic wave generator 13, and a movement amount instruction of the stub 34 to the phase control unit 32.

  The frequency variable control unit 20, the electromagnetic wave generator 13, and the phase control unit 32 perform appropriate control based on the received signal, and control so as to appropriately heat the temperature of the filter body 12.

  FIG. 19 is an algorithm example showing the control of the exhaust purification device 30 shown in FIG. For example, an example of control with a frequency pattern as shown in FIG. 8 is shown.

  After the operation is started, the frequency f1 is selected (S301), instructed, and the frequency is set by the frequency variable control unit 20 (S302). Next, an output instruction is given to the electromagnetic wave generator 13 to turn on the output (S303), and a timer (not explicitly shown in FIG. 17) is started (S304). As a result, the electromagnetic wave 14 is sent to the filter main body 12 to start heating, but the power consumed on the filter main body 12 side is calculated from the ratio of transmission / reflected power monitored by the bidirectional coupler 31 as a power monitor. Calculate (S305). Here, when the power consumption is small (No in S306), it is determined that the matching condition is not satisfied and the power is not effectively transmitted to the filter body 12, and therefore, the position control of the stub 34 is performed. 32 (S307), the position of the stub 34 is controlled so that the power consumption is increased, and the electromagnetic wave generator 13 is instructed to increase the output.

  When the power consumption is equal to or higher than the specified value (Yes in S306), the temperature of the filter main body 12 (including not only the filter directly but also the case of measuring the ambient temperature or the temperature of PM) is within the specified time limit (for example, the ambient temperature or PM temperature). , The combustion start temperature of PM) is reached (S308 and S309), and if the temperature of the filter body 12 does not reach the specified temperature within the startup limit time (Yes in S309), it is determined that the system is abnormal. System error handling. That is, the output OFF is instructed to the electromagnetic wave generator 13 (S310), and an alarm is notified (S311).

If the temperature has risen normally (Yes in S308), the timer is reset (S312), and heating is continued until the specified time T1. When the critical temperature limit H _Limit is exceeded (Yes in S313), system abnormality processing is immediately performed (S310 and S311).

  If the timer T1 can be continued normally (Yes in S314), the output from the electromagnetic wave generator 13 is turned off and the timer is reset (S315). The frequency is changed to f2 and the time is read as T2. (S316) The same process is performed again.

  If this is completed normally, an end notification is made (S317), and normal end processing is performed. Thereby, it is possible to realize a more effective filter regeneration process by changing the frequency.

<Second Modification>
FIG. 20 is a diagram illustrating an example of a configuration of an exhaust purification device 40 according to a second modification of the embodiment. FIG. 21 is a diagram showing an example of the configuration of an electromagnetic wave generator 41 applied to the exhaust gas purification device 40 shown in FIG. This exhaust purification device 40 is an example in which the output / phase control function shown in the first modification is incorporated in the electromagnetic wave generator 41.

  In the exhaust emission control device 40 shown in FIG. 20, the phase control unit is built in the electromagnetic wave generator as shown in FIG. That is, the electromagnetic wave generator 41 shown in FIG. 20 includes a variable frequency signal source 42, a phase shifter 43, a variable attenuator 44, a solid-state amplifier 45, and a coaxial waveguide converter 46.

  In the same operation as the algorithm shown in FIG. 19, instead of the instruction signal to the phase control unit, an output / phase instruction signal is transmitted from the determination unit 33 to the electromagnetic wave generator 41. Inside the electromagnetic wave generator 41 (FIG. 21), the variable frequency signal source 42 determines the oscillation frequency according to the frequency instruction, performs phase control by the phase shifter 43, and output control by the variable attenuator 44. The solid-state amplifier 45 amplifies the oscillated electromagnetic wave 14 and is guided to the coaxial waveguide converter 46, and the electromagnetic wave 14 is radiated into the space in the cylindrical body 17 by the coaxial waveguide converter 46 and is applied to the filter body 12. It is transmitted toward.

  Even with such a configuration, more effective filter regeneration processing can be realized by appropriately controlling the output and phase.

  When the output / phase support function is not included in the electromagnetic wave generator, the configuration of the electromagnetic wave generator is a configuration in which the phase shifter 43 and the variable attenuator 44 are omitted from the configuration shown in FIG.

  According to the exhaust emission control devices 10, 10 ′, 30, and 40 according to the embodiments described above, the variable frequency control that variably controls the frequency of the electromagnetic wave 14 generated from the devices 13 and 41 to the electromagnetic wave generation devices 13 and 41. The unit 20 is connected. Then, the frequency variable control unit 20 changes the frequency of the electromagnetic wave 14 applied to the filter main body 12 over time within a predetermined frequency band including the boundary frequency f between the single mode oscillation frequency and the multimode oscillation frequency. Therefore, the intensity distribution of the electromagnetic wave 14 in the filter main body 12 can be significantly changed over time. As a result, the occurrence of a temperature difference at each position in the filter body 12 can be suppressed, and the regeneration process of the filter body 12 is performed satisfactorily.

  Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Exhaust gas 10, 10 ', 30, 40 ... Exhaust gas purification device 11 ... Particulate matter (PM) deposition process part 12 ... Filter body 13, 41 ... Electromagnetic wave generator 14 ... electromagnetic waves 15a, 15b ... quartz plates 16a, 16b ... conductor walls 17, 17c, 17s, 17 '... cylindrical body 18 ... terminator 19 ... cavity resonator 20 ... Frequency variable control unit 21 ... Temperature sensor 31 ... Bidirectional coupler 32, 42 ... Phase control unit 33 ... Judgment unit 34 ... Stub 35 ... Drive motor 42 ... Variable frequency signal source 43 ... Phase shifter 44 ... Variable attenuator 45 ... Solid-state amplifier 46 ... Coaxial waveguide converter

Claims (10)

A filter body for capturing particulate matter contained in the exhaust gas;
A conductive outer container containing the filter body;
An electromagnetic wave generator for generating an electromagnetic wave having a variable frequency;
A frequency control unit that variably controls the frequency of the electromagnetic wave generated in the electromagnetic wave generator within a predetermined band;
Comprising
An exhaust emission control device configured to heat the particulate matter directly or indirectly attached to the filter body by irradiating the filter body with the electromagnetic wave,
The frequency control unit has a function of changing a propagation mode of the electromagnetic wave generated inside the outer container with time so as to cross a frequency for generating a single mode and a frequency for generating a multimode in the filter body. An exhaust purification device characterized by that.   2. The reflector according to claim 1, wherein a reflection plate that reflects the electromagnetic wave is provided on at least a side of the outer container from which the exhaust gas is discharged, and constitutes a cavity resonator in the outer container. The exhaust emission control device described.   3. The exhaust according to claim 1, further comprising a function of measuring a temperature of the filter main body, and a function of controlling irradiation of the electromagnetic wave generated from the electromagnetic wave generation device according to the temperature of the filter main body. Purification equipment.   The exhaust emission control device according to any one of claims 1 to 3, wherein the frequency of the electromagnetic wave generated in the electromagnetic wave generation device is such that the ratio of the center frequency and the bandwidth of the band to be changed is within 10%. .   5. The exhaust emission control device according to claim 4, wherein a center frequency of the band to be changed is not less than 902 MHz and not more than 928 MHz.   5. The exhaust emission control device according to claim 4, wherein a center frequency of the band to be changed is 2400 MHz to 2500 MHz.   The exhaust emission control device according to claim 4, wherein a center frequency of the band to be changed is 5725 MHz or more and 5875 MHz or less.   A band with a center frequency of 902 MHz to 928 MHz and a bandwidth of 26 MHz or less, or a center frequency of 2400 MHz to 2500 MHz and a bandwidth of 100 MHz or less, or a center frequency of 5725 MHz to 5875 MHz. The exhaust emission control device according to claim 4, wherein the exhaust purification device has a width of 150 megahertz or less. The function of controlling the output or phase of the electromagnetic wave radiated to the filter body, the function of detecting the intensity of the electromagnetic wave radiated to the filter body, and the electromagnetic wave radiated to the filter body according to the intensity value of the electromagnetic wave A determination unit that indicates the output or phase of
The exhaust gas purification according to any one of claims 1 to 8, which has a function of controlling an output or a phase of the electromagnetic wave so that electric power absorbed by the filter body is maximized for each of the single mode and the multi-mode states. apparatus.   The exhaust emission control device according to claim 9, wherein a part or all of the function of controlling the output or the phase is provided in the electromagnetic wave generator.

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