JP2007224815A - Fuel reforming method, fuel reforming device and nitrogen oxide treatment device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel reforming method forming reformed fuel having high NOx reduction efficiency, a fuel reforming device enabling the fuel reforming method, and a nitrogen oxide treatment device reducing NOx by using reformed fuel produced by the fuel reforming device. <P>SOLUTION: The nitrogen oxide treatment system detects a NOx quantity contained in exhaust gas by an NOx sensor 69 from exhaust gas flowing in a channel 63 and estimates a component of NOx from the state of a diesel engine 60. Then, the fuel reforming device 10 irradiates gas oil in a storage vessel 15 with an ultrasonic wave of a first frequency belonging to a frequency range of 200kHz to 400kHz or an ultrasonic wave of a second frequency belonging to a frequency range of 600kHz to 800kHz to produce reformed fuel suitable for the reduction of the estimated NOx. Moreover, an adjustment valve 41 of a fuel injection mechanism 40 is opened and reformed fuel produce by the fuel reforming device 10 is injected according to the detected NOx quantity. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel reforming method for reforming fuel, a fuel reforming apparatus using the fuel reforming method, and a nitrogen oxide processing apparatus for reducing nitrogen oxide using a reducing agent obtained by the fuel reforming apparatus. About.

  In recent years, NOx selection that reduces NOx contained in exhaust gas by injecting a reducing agent (hereinafter referred to as NOx reducing agent) that reduces nitrogen oxides (hereinafter referred to as NOx) into exhaust gas discharged from an internal combustion engine. A nitrogen oxide processing apparatus using a reduction method (hereinafter referred to as HC-SCR) is known (see, for example, Patent Document 1).

In HC-SCR, generally, light oil or a reformed fuel obtained by reforming light oil is used as a NOx reducing agent.
In addition, since light oil contains many linear hydrocarbons with a large carbon number, when light oil is reformed, various hydrocarbons are generated from those having a large carbon number to those having a small carbon number.

  Here, FIG. 6 (A) shows the influence of the carbon number and molecular bond of hydrocarbons on the reduction of NOx, and FIG. 6 (B) shows that the carbon number of linear hydrocarbons is NOx. It shows the effect on reduction.

As shown in FIG. 6 (A), straight chain hydrocarbons have a higher NOx reduction rate compared to the case where NOx is reduced using general light oil, and are suitable as a reducing agent used in HC-SCR. ing. However, as shown in FIG. 6 (B), (C ₄ order of C ₁₎ number is less linear hydrocarbons carbon has a low NOx reducing rate at a temperature of the exhaust gas discharged from an internal combustion engine It is unsuitable as a reducing agent used in HC-SCR.

That is, as a NOx reducing agent used in HC-SCR, it is known that C ₈ to C ₁₂ hydrocarbons are suitable among linear hydrocarbons (see, for example, Non-Patent Document 1).
In addition, as one method of generating this hydrocarbon, cavitation is generated by the gas dissolved in the fuel by irradiating the fuel (light oil, etc.) for the internal combustion engine with ultrasonic waves, thereby reforming the components of the fuel. (The final product is a reformed fuel containing hydrocarbons).
JP-A-5-237336 Takahashi, Tatsumi, “Development of hydrocarbon reduction type NOx catalyst for diesel engine”, Preprint of Academic Lecture, Japan Society for Automotive Engineers, No. 29-04, p. 5-8

  However, in the conventional reforming method, various hydrocarbons are generated from those having a large number of carbon atoms to those having a small number, and there is a problem that the reduction efficiency is low even if NOx is reduced using this reformed fuel. there were.

  Therefore, the present invention uses a fuel reforming method for generating reformed fuel with good NOx reduction efficiency, a fuel reforming device for realizing the fuel reforming method, and a reformed fuel generated by the fuel reforming device. It aims at providing the nitrogen oxide processing apparatus which reduces NOx.

  In order to achieve the above object, the fuel reforming method of the present invention irradiates light oil with ultrasonic waves having a frequency belonging to an irradiation frequency band consisting of 200 kHz to 400 kHz or 600 kHz to 800 kHz, and converts the light oil into reformed fuel. It is a quality.

According to the research conducted by the inventors of the present invention, there is a high correlation between the frequency of ultrasonic waves irradiated to light oil and the concentration of C ₁₀ to C ₁₂ hydrocarbons generated when the ultrasonic waves are irradiated. It has been found that there is a relationship, and the fuel reforming method of the present invention is based on that knowledge.

That is, as shown in FIG. 7, the inventors of the present invention have C ₁₀ , C ₁₁ hydrocarbons at frequencies of 200 kHz to 400 kHz, and C ₁₀ , C ₁₁ , C ₁₂ at frequencies of 600 kHz to 800 kHz. The knowledge that many hydrocarbons are produced was obtained.

For this reason, according to the fuel reforming method of the present invention, when irradiated with ultrasonic waves having a frequency belonging to the irradiation frequency band of 200 kHz to 400 kHz, the reformed fuel contains more C ₁₀ and C ₁₁ hydrocarbons than light oil. When it is irradiated with ultrasonic waves having a frequency belonging to an irradiation frequency band consisting of 600 kHz to 800 kHz, it becomes a reformed fuel containing more C ₁₀ , C ₁₁ , and C ₁₂ hydrocarbons than light oil. It can be modified.

  That is, according to the fuel reforming method of the present invention, it is possible to reform from light oil to a reformed fuel in which hydrocarbons suitable as a reducing agent for nitrogen oxides are increased. For this reason, the reformed fuel containing many hydrocarbons suitable as a reducing agent of nitrogen oxides can be obtained.

Further, in the fuel reforming method of the present invention, it is desirable to mix bubbles before or during irradiation with ultrasonic waves in the bubble mixing process.
According to the fuel reforming method of the present invention, bubbles that become the core of cavitation are mixed, so that cavitation is easily generated, and the time required for generating reformed fuel suitable as a reducing agent can be shortened.

  In the fuel reformer of the present invention, the fuel storage means stores light oil, and the ultrasonic irradiation means uses light oil stored in the fuel storage means in a frequency belonging to an irradiation frequency band consisting of 200 kHz to 400 kHz or 600 kHz to 800 kHz. The ultrasonic wave is irradiated.

  That is, the fuel reforming apparatus of the present invention is an apparatus for realizing the above-described fuel reforming method of the present invention. For this reason, according to the fuel reformer of the present invention, light oil can be reformed into a reformed fuel containing a large amount of hydrocarbons suitable as a reducing agent for nitrogen oxides.

  Further, the ultrasonic irradiation means in the fuel reformer of the present invention is such that at least the vibration means having a vibration surface that generates the ultrasonic waves receives the signal generated by the signal generation means and vibrates to generate ultrasonic waves. It may be configured to occur.

  Furthermore, the fuel reformer of the present invention is provided with a reflection member having a reflection surface for reflecting ultrasonic waves in the fuel storage means, facing the vibration surface of the vibration means, and the wavelength of the ultrasonic wave from the vibration surface. The reflecting surface may be disposed at a position separated by an integer multiple of.

  According to the fuel reforming apparatus of the present invention configured as described above, since the standing oil can be irradiated to the light oil in the fuel storage means, the reformed fuel containing a large amount of hydrocarbons suitable as a reducing agent from the light oil. Can be efficiently modified.

In the fuel reformer of the present invention, it is desirable that the bubble mixing means mix bubbles into the light oil stored in the fuel storage means.
That is, the fuel reforming apparatus of the present invention is an apparatus for realizing the above-described fuel reforming method (claim 2). For this reason, according to the fuel reforming apparatus of the present invention, it is possible to shorten the time required for generating reformed fuel suitable as a reducing agent.

By the way, as an energy source required when C ₈ to C ₁₂ hydrocarbons suitable as a reducing agent are produced from linear hydrocarbons having a large number of carbon atoms contained in light oil, an aradical reaction generated by cavitation is used as an energy source. (Oxygen radical reaction) is considered.

  For this reason, it is desirable that the air bubbles mixed in the light oil by the air bubble mixing means are composed of a gas containing oxygen atoms that generate an aradical reaction when receiving ultrasonic waves emitted from the ultrasonic wave irradiation means.

  Further, in the nitrogen oxide treatment apparatus of the present invention, the reformed fuel injection means is reformed by the fuel reformer of the present invention in a conduit through which exhaust gas containing at least nitrogen oxide and exhausted from the internal combustion engine flows. The reformed fuel is ejected. A mixed gas of reformed fuel and exhaust gas is then disposed on the conduit and passes through a catalyst that promotes the reduction of nitrogen oxides.

  That is, the nitrogen oxide processing apparatus of the present invention is a nitrogen oxide processing apparatus that performs reduction of nitrogen oxides using the reformed fuel that is reformed by the fuel reforming apparatus of the present invention described above. For this reason, according to the nitrogen oxide processing apparatus of this invention, the nitrogen oxide contained in exhaust gas can be reduced efficiently.

  Further, in the nitrogen oxide treatment apparatus of the present invention, the nitrogen oxide detection means detects the amount or component of nitrogen oxide contained in the exhaust gas, and the reformed fuel deriving means determines the detection result of the nitrogen oxide detection means. Based on this, the reformed fuel information related to the amount or component of the reformed fuel necessary for the reduction of nitrogen oxides is derived, and the control means converts the reformed fuel information corresponding to the reformed fuel information derived by the reformed fuel deriving means. Reform control for controlling the fuel reformer so as to reform, or jet for controlling the reformed fuel ejection means so as to eject the reformed fuel corresponding to the reformed fuel information derived by the reformed fuel deriving means It is desirable that at least one of the controls is configured to be executed.

  According to the nitrogen oxide treatment apparatus of the present invention configured as described above, the amount of reformed fuel reformed by the fuel reformer according to the amount and components of nitrogen oxide contained in the exhaust gas. Alternatively, the amount of the reformed fuel or the component of the reformed fuel ejected by the reformed fuel ejection means or the component is changed to that required for the reduction, so that the nitrogen oxides in the exhaust gas can be reliably reduced.

  Further, when the state of the internal combustion engine changes, the nitrogen oxide component and amount contained in the exhaust gas discharged from the internal combustion engine change. For example, when the combustion temperature in the internal combustion engine rises, the amount of nitrogen monoxide and nitrogen dioxide contained in the exhaust gas increases.

  Therefore, in the nitrogen oxide treatment apparatus of the present invention, the internal combustion engine detection means detects the state of the internal combustion engine, and the estimation means determines the amount of nitrogen oxide contained in the exhaust gas based on the detection result of the internal combustion engine detection means. Alternatively, it is desirable to estimate the components and use the estimation result as the detection result of the nitrogen oxide detection means.

  That is, according to the nitrogen oxide treatment apparatus of the present invention, the amount estimated based on the state of the internal combustion engine or the component nitrogen oxide is reformed into the optimum amount or component reformed fuel. Since reforming control (or jetting control) is executed, nitrogen oxides in the exhaust gas can be reliably reduced regardless of the state of the internal combustion engine.

  In the nitrogen oxide treatment apparatus of the present invention, the state of the internal combustion engine is detected by detecting the rotational speed of the internal combustion engine, the temperature of the exhaust gas, the flow rate of the exhaust gas, and the temperature of the air supplied to the internal combustion engine. Also good.

  Further, when the reduction efficiency of nitrogen oxides in the catalyst decreases, the amount of nitrogen oxides remaining in the exhaust gas discharged to the outside of the nitrogen oxide treatment apparatus increases. That is, for example, even when the same amount of reformed fuel is ejected as before the reduction efficiency is reduced, the reduction efficiency is reduced, so that the nitrogen oxides are not reduced and discharged outside the nitrogen oxide treatment apparatus. The

  For this reason, in the nitrogen oxide treatment apparatus of the present invention, the reduction efficiency calculation means calculates the reduction efficiency when the nitrogen oxide is reduced based on the catalyst temperature detected by the catalyst temperature detection means, and derives the reformed fuel. Preferably, the means derives the reformed fuel information based on the reduction efficiency calculated by the reduction efficiency calculation means.

  That is, according to the nitrogen oxide treatment apparatus of the present invention, reforming control for reforming to reformed fuel necessary for reducing nitrogen oxide under the reduction efficiency calculated from the temperature of the catalyst (or Therefore, nitrogen oxides in the exhaust gas can be reliably reduced regardless of the reduction efficiency.

  By the way, when the fuel reformer reforms from light oil to reformed fuel, the component ratio of the reformed reformed fuel is different when the state of the light oil is different even if the frequency of the ultrasonic wave irradiated to the light oil is the same. It is not always constant. That is, depending on the state of the light oil, reformed fuel that is inappropriate as a reducing agent is generated.

  Therefore, in the nitrogen oxide treatment apparatus of the present invention, the reforming efficiency calculating means reforms the fuel reformer from light oil based on the state of the supplied light oil supplied to the fuel reformer detected by the light oil condition detecting means. It is desirable that the reforming efficiency when reforming into fuel is calculated, and the reformed fuel deriving unit derives the reformed fuel information based on the reforming efficiency calculated by the reforming efficiency calculating unit.

  In other words, according to the nitrogen oxide treatment apparatus of the present invention, the reforming for reforming the reformed fuel into the reformed fuel in an amount or component necessary for reducing the nitrogen oxide under the reforming efficiency calculated from the state of the light oil. Since the quality control is executed, nitrogen oxides contained in the exhaust gas can be reliably reduced regardless of the state of the light oil.

And in the nitrogen oxide processing apparatus of this invention, you may detect the state of light oil by detecting any one among the temperature of supply light oil, and the component ratio of supply light oil.
In the nitrogen oxide treatment apparatus of the present invention, the catalyst preferably contains silver and is supported on an alumina carrier.

  According to the nitrogen oxide treatment apparatus of the present invention configured as described above, since the catalyst containing silver and supported on the alumina carrier further promotes the action of the reducing agent, the nitrogen oxide in the exhaust gas is efficiently removed. Can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<About device configuration>
FIG. 1 is an explanatory diagram showing a schematic configuration around a nitrogen oxide treatment system mounted on a vehicle, and FIG. 2 is an explanatory diagram showing a configuration around an internal combustion engine (that is, a diesel engine).

  As shown in FIG. 2, a vehicle using light oil as a fuel includes a fuel supply system that supplies light oil stored in a fuel tank 62 to a diesel engine 60 via a fuel pump 61, and nitrogen exhausted from the diesel engine 60. And an exhaust system that exhausts exhaust gas containing oxide (hereinafter referred to as NOx) to the outside of the vehicle by flowing in the conduit 63.

  As shown in FIG. 1, the nitrogen oxide treatment system includes a fuel reformer 10 that reforms light oil supplied from a fuel tank 62 via a fuel pump 61 into reformed fuel, and a conduit 63. A fuel injection mechanism 40 for injecting the reformed fuel reformed by the fuel reformer 10 into the flowing exhaust gas, a catalyst unit 64 for promoting the function of the reformed fuel (that is, the reducing agent), and the fuel reformer ECU 65 for controlling the component ratio of the reformed fuel reformed at 10 and the amount of reformed fuel ejected from the fuel ejection mechanism 40.

  Further, the nitrogen oxide treatment system is disposed in a fuel tank 62 and a NOx sensor 69 that detects the amount of NOx contained in the unit flow rate of the exhaust gas before flowing through the conduit 63 and before the reformed fuel is ejected. A gas oil temperature sensor 71 for detecting the temperature of light oil, an intake gas flow rate sensor 72 for detecting the amount of air supplied to the diesel engine 60, an intake gas temperature sensor 73 for detecting the temperature of air supplied to the diesel engine 60, An exhaust gas temperature sensor 74 that detects the temperature of exhaust gas discharged from the diesel engine 60, a catalyst temperature sensor 77 that detects the temperature of the catalyst unit 64, and an accelerator opening sensor 75 that detects the amount of depression of the accelerator 67 shown in FIG. , A sensor comprising a crank angle sensor 76 for detecting the crank angle of the diesel engine 60 Group 70 is provided.

  Further, the catalyst unit 64 shown in FIG. 1 is configured such that a catalyst containing silver and reducing NOx is accommodated in an alumina carrier, and is configured to form a part of the conduit 63. A catalyst temperature control device 31 for controlling the temperature of the catalyst is disposed in the vicinity of the catalyst unit 64.

  The fuel ejection mechanism 40 has a valve mechanism for adjusting the amount of reformed fuel, and includes an adjustment valve 41 controlled by the ECU 65 and a nozzle that ejects the amount of reformed fuel adjusted by the adjustment valve 41. And the like. As the fuel ejection mechanism 40, a known injector or the like that ejects fuel into a cylinder of an engine may be used.

That is, in this nitrogen oxide treatment system, the exhaust gas discharged from the diesel engine 60 to the outside of the vehicle using the conduit 63 is on the route of the NOx amount and components contained in the exhaust gas by the NOx sensor 69 and the like. Is detected. When the adjustment valve 41 of the fuel ejection mechanism 40 is opened, the reformed fuel is ejected from the fuel ejection mechanism 40. The reformed fuel ejected from the fuel ejection mechanism 40 is mixed with the exhaust gas, and the mixed gas flows through the conduit 63 and passes through the catalyst unit 64. When the mixed gas passes through the catalyst unit 64, the function of the reformed fuel (that is, the function as a reducing agent) is promoted, so that the reduction of NOx contained in the exhaust gas proceeds and NOx is reduced. Exhaust gas into the atmosphere.
<About fuel reformer>
The fuel reformer 10 includes a bubble generator 11 that mixes bubbles into light oil supplied from the fuel tank 62, a storage container 15 that stores light oil mixed with bubbles by the bubble generator 11, and a storage container 15 that stores the fuel oil. And an ultrasonic generator 20 for irradiating the light oil with ultrasonic waves.

  First, the bubble generating device 11 is configured around a well-known micro bubble generating device, and light oil with air in the atmosphere (that is, a gas containing oxygen) as bubbles (the bubble diameter in this embodiment is about 1 to 100 μm). It is to be mixed in.

  In addition, the ultrasonic generator 20 includes a vibrator 21 that generates ultrasonic waves when the vibration surface vibrates, and an amplifier 25 that amplifies a drive signal output from the ECU 65 and transmits the amplified drive signal to the vibrator 21. .

  The vibrator 21 is a member mainly composed of a piezoelectric element that expands and contracts by application of a voltage, and is arranged such that a vibration surface that generates ultrasonic waves irradiates the inside of the storage container 15 with ultrasonic waves. ing. Since the shape of the vibrator 21 mainly composed of the piezoelectric element is deformed by a deformation amount corresponding to the magnitude of the applied voltage, when a drive signal whose voltage magnitude changes periodically is applied, Vibrates and generates ultrasonic waves.

  The storage container 15 is formed with a strength that can withstand cavitation that occurs when light oil stored in the storage container 15 is irradiated with ultrasonic waves from the vibrator 21. The storage container 15 includes a reflection member (not shown) having a reflection surface that reflects the ultrasonic waves generated by the vibrator 21 inside the light oil.

  In this fuel reformer 10, the bubble generator 11 mixes air in the atmosphere as bubbles into the light oil supplied from the fuel tank 62 via the fuel pump 61, and the light oil mixed with the bubbles is contained in the storage container 15. Store in. Further, the vibrator 21 that receives the drive signal output from the ECU 65 vibrates to generate ultrasonic waves, and irradiates the light oil in the storage container 15 with ultrasonic waves.

  The light oil irradiated with ultrasonic waves is a hydrocarbon suitable as a reducing agent (that is, a NOx reducing agent) by causing cavitation of gas dissolved in the light oil and bubbles mixed in the bubble generating device 11. Reformed into a reformed fuel containing

Here, FIG. 3 is a block diagram showing a control system of the nitrogen oxide treatment system.
The ECU 65 is configured around a well-known microcomputer including a CPU, a ROM, and a RAM. The ECU 65 has a component ratio of reformed fuel reformed by the fuel reformer 10 and an amount of reformed fuel ejected by the fuel ejection mechanism 40. Is executed, and a drive signal having a frequency determined in the fuel reforming ejection process is output to the amplifier 25 (that is, the fuel reformer 10). That is, the ECU 65 executes a process such as a fuel reforming ejection process based on the detection result of the sensor group 70, and causes the fuel reforming apparatus 10 and the fuel ejection mechanism 40 to reduce NOx contained in the exhaust gas. It is something to control.

  Next, a drive signal output from the ECU 65 and input to the vibrator 21 is shown in FIG. As shown in the figure, the drive signal is a high-frequency continuous wave and has a frequency determined by a fuel reforming ejection process described later.

  When such a drive signal is input to the vibrator 21 via the amplifier 25, the vibrator 21 vibrates at the same frequency as the frequency of the drive signal, and an ultrasonic wave having the same frequency as the frequency of the drive signal is generated.

  And, as the frequency of the drive signal, a first frequency (350 kHz in this embodiment) belonging to the frequency band from 200 kHz to 400 kHz, and a second frequency (700 kHz in this embodiment) belonging to the frequency band from 600 kHz to 800 kHz, Is used.

The distance between the vibrating surface of the vibrator 21 and the reflecting surface of the reflecting member is set to be an integral multiple of the wavelength of the first frequency ultrasonic wave. That is, in this embodiment, since the second frequency is an integer multiple of the first frequency, the distance is set to the second frequency by setting the distance between the vibration surface and the reflection surface according to the first frequency having a small frequency. It is intended to satisfy an integer multiple of the wavelength in the ultrasonic wave of the frequency.
<About fuel reforming treatment>
Next, the fuel reforming ejection process executed by the ECU 65 will be described using the flowchart shown in FIG.

  In the ROM of the ECU 65, the reformed fuel having the optimum component as the reducing agent is generated by the fuel reformer 10 according to the amount and the component of NOx based on the result obtained through experiments and the like. In the fuel reformer 10, detection results such as the amount of NOx, the exhaust gas temperature, the intake gas temperature, the temperature of the catalyst unit 64, and the like so that an optimal amount of reformed fuel as an agent is ejected from the fuel ejection mechanism 40. A drive signal table is stored in which the frequency of the irradiated ultrasonic wave and the opening amount of the adjustment valve 41 of the fuel ejection mechanism 40 are associated with each other.

  This drive signal table shows the amount of NOx and the fuel injection mechanism 40 so that the amount of reformed fuel injected from the fuel injection mechanism 40 increases when the amount of NOx contained in the exhaust gas increases. It has an item in which the opening amount of the regulating valve 41 is associated.

  Further, the drive signal table indicates that the amount of reformed fuel ejected from the fuel ejection mechanism 40 is increased when the reduction efficiency (that is, the function of the catalyst) of the catalyst unit 64 decreases. There is an item in which the temperature of the catalyst unit 64, which is an index for determining the reduction efficiency, and the opening amount of the adjustment valve 41 of the fuel ejection mechanism 40 are associated with each other.

Further, in a general diesel engine, the NOx component (that is, the ratio of nitrogen monoxide, nitrogen dioxide, etc.) contained in the exhaust gas varies depending on the state of the diesel engine. In such a case, the component ratio of the reformed fuel used for the reduction (that is, the ratio of C ₁₀ to C ₁₂ hydrocarbons suitable as a reducing agent) differs depending on the NO x component. Therefore, it needs to be reformed into a reformed fuel suitable for reduction. For this reason, the drive signal table includes the exhaust gas temperature, which is an index for determining the NOx component, so that reformed fuel suitable for reduction is generated according to the NOx component contained in the exhaust gas. There are items in which the intake gas temperature, the amount of air supplied to the diesel engine, and the like are associated with the frequency of the ultrasonic wave irradiated by the fuel reformer 10.

Further, the drive signal table indicates that the reforming component component ratio is suitable for use as a NOx reducing agent when the reforming efficiency when reforming from light oil to reformed fuel is reduced in the fuel reformer 10. The fuel reformer 10 has a fuel oil temperature, an outside air temperature, etc., which are indicators for judging reforming efficiency, so that the fuel is maintained (that is, the amount of C ₁₀ to C ₁₂ hydrocarbons generated is maintained). It has an item that correlates the frequency of the ultrasonic wave to be irradiated.

  This fuel reforming ejection process is executed when the diesel engine 60 is started. When the fuel reforming injection process is executed, first, in S210, the accelerator opening detected by the accelerator opening sensor 75 and the crank angle detected by the crank angle sensor 76 (that is, the engine speed). To get.

  In S220, the engine load is calculated based on the accelerator opening and the crank angle acquired in S210, and the flow rate of exhaust gas discharged from the diesel engine 60 is calculated based on the calculated engine load.

  In S230, the temperature of the light oil detected by the light oil temperature sensor 71, the air flow detected by the intake gas flow sensor 72, the temperature of the air detected by the intake gas temperature sensor 73, and the exhaust gas temperature sensor 74 are detected. The temperature of the exhaust gas to be detected and the temperature of the catalyst unit 64 detected by the catalyst temperature sensor 77 are acquired.

  Subsequently, in S240, the amount of NOx detected by the NOx sensor 69 is acquired, and the amount of NOx contained in the exhaust gas is calculated based on the acquired amount of NOx and the flow rate of the exhaust gas calculated in S220. To do.

  In S250, based on the detection results such as the temperature of the light oil, the flow rate of air, the temperature of the air, the temperature of the exhaust gas, etc. acquired in S230, a super signal corresponding to the detection result is stored in the drive signal table stored in the ROM. Reads the frequency of the sound wave. That is, in S250, the frequency of the ultrasonic wave irradiated by the fuel reformer 10 is determined (that is, either 350 kHz or 700 kHz is selected in this embodiment).

  Subsequently, in S260, based on the detection result such as the amount of NOx contained in the exhaust gas calculated in S240 and the temperature of the catalyst unit 64 acquired in S230, the detection result is obtained from the drive signal table stored in the ROM. The opening amount of the regulating valve 41 corresponding to is read. That is, in S260, the amount of reformed fuel ejected from the fuel ejection mechanism 40 is determined.

In S270, the drive signal having the frequency determined in S250 is output to the fuel reformer 10.
Further, in S270, in addition to the drive signal, an opening signal for opening the regulating valve 41 is output in order to eject the amount of reformed fuel ejected by the fuel ejection mechanism 40 determined in S260 into the exhaust gas. For this reason, the regulating valve 41 that has received the opening signal opens the valve mechanism and injects the reformed fuel into the exhaust gas flowing through the exhaust gas conduit.

  The timing at which the fuel ejection mechanism 40 ejects the reformed fuel is controlled so as to be synchronized with the exhaust timing of the diesel engine 60 detected by the crank angle sensor 76, and the same amount as the reformed fuel to be ejected. The fuel pump 61 is controlled so that the light oil is supplied to the fuel reformer 10.

Then, after outputting the drive signal and the release signal in S270, the process returns to S210.
That is, in the fuel reforming injection process, as long as the diesel engine 60 is operating, the steps from S210 to S270 are repeatedly executed.

<Effect of the embodiment>
As described above, according to the fuel reformer 10 of the present embodiment, the first frequency belonging to the frequency band from 200 kHz to 400 kHz or the ultrasonic wave having the second frequency belonging to the frequency band from 600 kHz to 800 kHz is irradiated. Therefore, the reformed fuel containing a large amount of C ₁₀ to C ₁₂ hydrocarbons suitable as a reducing agent can be efficiently produced. For this reason, according to the nitrogen oxide treatment system of the present embodiment that reduces NOx using the reformed fuel generated by the fuel reformer 10, NOx contained in the exhaust gas can be efficiently reduced. As a result, according to the nitrogen oxide treatment system of the present embodiment, NOx contained in the exhaust gas discharged outside the vehicle can be reduced.

  Further, the fuel reformer 10 is configured to select the frequency of the ultrasonic wave applied to the light oil from the first frequency or the second frequency. For this reason, according to the nitrogen oxide treatment system of the present embodiment, the component of the reformed fuel generated by the fuel reformer 10 can be controlled in accordance with the amount of NOx in the exhaust gas and the component of NOx. . Further, according to the nitrogen oxide treatment system of the present embodiment, the amount of reformed fuel injected from the fuel injection mechanism 40 can be controlled in accordance with the amount of NOx in the exhaust gas and the NOx component. As a result, according to the nitrogen oxide treatment system of the present embodiment, NOx in the exhaust gas can be reliably reduced.

  Further, in the fuel reformer 10, the bubble generating device is configured to mix bubbles into the light oil. For this reason, according to the fuel reformer 10, since cavitation is likely to occur during the irradiation of ultrasonic waves, the time required for generating the reformed fuel can be shortened. Furthermore, according to the fuel reformer 10, since the mixed bubbles contain oxygen atoms that cause an aradical reaction by cavitation, reforming can be promoted and reformed fuel can be generated efficiently.

  Further, in the fuel reformer 10, the second frequency is set to an integral multiple of the first frequency, and the distance between the vibration surface of the vibrator 21 and the reflection surface of the reflecting member is the wavelength of the first frequency ultrasonic wave. It is set to be an integer multiple of. For this reason, according to the fuel reformer 10, regardless of the first frequency or the second frequency, a standing wave is generated between the vibration surface and the reflection surface, so that the ultrasonic vibration is efficiently converted to light oil. Can communicate.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it is possible to implement in various aspects.

  For example, in the present embodiment, the drive signal output from the ECU 65 is a high-frequency sine wave as shown in FIG. 4, but is not limited thereto, and may be a high-frequency rectangular wave. That is, the drive signal may be any signal that vibrates the vibrator 21 and generates an ultrasonic wave having a frequency belonging to a frequency band of 200 kHz to 400 kHz or 600 kHz to 800 kHz.

  Moreover, although the reflective member which reflects an ultrasonic wave was provided in the fuel reformer 10 in this embodiment, the reflective member may be omitted, and the side wall of the storage container 15 may be used as a reflective surface.

  In the present embodiment, the vibrator 21 of the fuel reformer 10 is configured with a piezoelectric element as the center, but is not limited thereto. That is, any device that vibrates in accordance with a signal output from the ECU 65 and generates ultrasonic waves may be used.

  Furthermore, the fuel reforming apparatus 10 in the present embodiment is not limited to that used by being mounted on a vehicle. In other words, any fuel oil may be used as long as it is supplied with light oil and irradiates ultrasonic waves to generate reformed fuel. However, when the fuel reformer 10 is used outside the vehicle, it is desirable that a signal output unit for outputting a drive signal for driving the vibrator 21 is provided in the fuel reformer.

  In addition, the gas taken in by the bubble generation device 11 to generate bubbles is not limited to air in the atmosphere. For example, the bubble generating device 11 may include a tank that stores gas (oxygen, ozone, or the like) and a gas supply device, and the bubbles may be mixed into light oil using the gas supplied from the tank. In this case, by storing oxygen and ozone in the tank, these gases can be mixed into the light oil as bubbles.

  In addition, although one fuel reformer is provided in the nitrogen oxide treatment system in the present embodiment, a plurality of fuel reformers may be provided. In this case, by making the frequency of the ultrasonic wave irradiated by each fuel reformer different, the component ratio of hydrocarbons in the reformed fuel to be generated can be controlled more reliably. Therefore, according to the nitrogen oxide treatment system configured to have a plurality of fuel reformers, NOx in the exhaust gas is reduced by using the reformed fuel reformed by these fuel reformers. It can reduce more reliably.

  Furthermore, in the nitrogen oxide treatment system according to the present embodiment, the reformed fuel is injected into the exhaust gas flowing in the conduit 63 from the fuel injection mechanism 40, but is not limited thereto. For example, the fuel injection mechanism 40 is provided in the diesel engine 60, and the exhaust gas before being discharged from the diesel engine 60 (in general, the state where the combustion stroke is completed, that is, the exhaust gas remaining in the cylinder before the exhaust stroke) Alternatively, the reformed fuel may be ejected.

  In addition, the driving signal table of the nitrogen oxide treatment system in the present embodiment includes the detection result of the amount of NOx, the exhaust gas temperature, the intake gas temperature, the catalyst unit temperature, etc., the frequency of ultrasonic irradiation, and the reformed fuel injection The quantity is associated with, but is not limited to this. For example, the drive signal conditions are associated with detection results such as NOx amount, exhaust gas temperature, intake gas temperature, catalyst unit temperature, diesel oil temperature, etc., ultrasonic irradiation time, ultrasonic sound pressure or duty ratio, etc. It may be the one given.

  In other words, the drive signal table reduces NOx so that almost all NOx contained in the exhaust gas is reduced (that is, NOx in the exhaust gas discharged to the outside of the vehicle is equal to or less than a predetermined value specified in advance). The detection results such as the amount of exhaust gas, the temperature of exhaust gas, the temperature of the catalyst, etc. are associated with the control target such as the reformed fuel injection amount, the reformed fuel component ratio, and the amount of reformed fuel produced. Anything is fine.

  Furthermore, the drive signal table may not be represented as a table. That is, it may be expressed by an equation that associates the detection result such as the amount of NOx with the frequency irradiated with ultrasonic waves and the injection amount of reformed fuel.

It is explanatory drawing which shows schematic structure of a nitrogen oxide processing apparatus and its periphery. It is explanatory drawing which shows schematic structure of a diesel engine periphery. It is a block diagram which shows the control system of a nitrogen oxide processing system. It is explanatory drawing which shows the drive signal which ECU outputs. It is a flowchart of the reforming injection process which produces | generates and injects reformed fuel. It is a graph which shows that hydrocarbon is suitable as a reducing agent of NOx. The experimental results showing the relationship between the C ₁₀ is generated and the concentration of hydrocarbon C ₁₂ when irradiated with the ultrasonic waves and the ultrasonic frequency is applied to the diesel fuel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Fuel reformer 11 ... Bubble generator 15 ... Storage container 20 ... Ultrasonic generator 21 ... Vibrator 25 ... Amplifier 40 ... Fuel injection mechanism 41 ... Adjustment valve 42 ... Injection mechanism 60 ... Diesel engine 61 ... Fuel pump 62 ... Fuel tank 63 ... Conduit 64 ... Catalyst unit 69 ... NOx sensor 70 ... Sensor group 71 ... Light oil temperature sensor 72 ... Intake gas flow rate sensor 73 ... Intake gas temperature sensor 74 ... Exhaust gas temperature sensor 75 ... Accelerator opening sensor 76 ... Crank Angle sensor 77 ... Catalyst temperature sensor

Claims (15)

A fuel reforming method in which light oil is irradiated with ultrasonic waves to reform the light oil into a reformed fuel,
The fuel reforming method according to claim 1, wherein the frequency of the ultrasonic wave irradiated to the light oil belongs to an irradiation frequency band consisting of 200 kHz to 400 kHz or 600 kHz to 800 kHz.   2. The fuel reforming method according to claim 1, further comprising a bubble mixing process in which bubbles are mixed into the light oil before or during irradiation with the ultrasonic wave. Fuel storage means for storing light oil;
Ultrasonic irradiation means for irradiating light oil stored in the fuel storage means with ultrasonic waves having a frequency belonging to an irradiation frequency band consisting of 200 kHz to 400 kHz or 600 kHz to 800 kHz;
A fuel reformer characterized by comprising: The ultrasonic irradiation means includes
Receiving a signal and vibrating to generate ultrasonic waves, and at least a vibrating means having a vibrating surface for generating the ultrasonic waves;
Signal generating means for generating a signal such that the vibrating means vibrates;
The fuel reformer according to claim 3, further comprising: A reflective member having a reflective surface for reflecting ultrasonic waves is provided in the fuel storage means,
5. The fuel according to claim 4, wherein the reflection surface is disposed at a position facing the vibration surface of the vibration means and separated from the vibration surface by a distance that is an integral multiple of the wavelength of the ultrasonic wave. Reformer.   The fuel reformer according to any one of claims 3 to 5, further comprising bubble mixing means for mixing bubbles in the light oil stored in the fuel storage means.   The bubbles mixed in the light oil by the bubble mixing means are composed of a gas containing oxygen atoms that generate an aradical reaction by receiving at least ultrasonic waves irradiated from the ultrasonic irradiation means. The fuel reformer according to claim 6. A fuel reformer according to any one of claims 3 to 7,
Reformed fuel injection means for injecting reformed fuel reformed by the fuel reformer into a conduit through which exhaust gas containing at least nitrogen oxides and exhausted from the internal combustion engine flows;
A catalyst that is disposed on the conduit through which a mixed gas of the reformed fuel ejected by the reformed fuel ejection means and the exhaust gas passes, and that promotes reduction of the nitrogen oxides;
A nitrogen oxide processing apparatus comprising: Nitrogen oxide detecting means for detecting the amount or component of the nitrogen oxide contained in the exhaust gas;
Reformed fuel deriving means for deriving reformed fuel information related to the amount or component of the reformed fuel necessary for the reduction of nitrogen oxides based on the detection result of the nitrogen oxide detecting means;
Reform control for controlling the fuel reformer so that the fuel reformer reforms the reformed fuel corresponding to the reformed fuel information derived by the reformed fuel deriving means, or the reformed fuel deriving Control means for executing at least one of ejection control for controlling the reformed fuel injection means so that the reformed fuel injection means ejects reformed fuel corresponding to the reformed fuel information derived by the means When,
The nitrogen oxide processing apparatus according to claim 8, comprising: An internal combustion engine detection means for detecting the state of the internal combustion engine;
The nitrogen oxide detection means estimates the amount or component of nitrogen oxide contained in the exhaust gas based on the detection result of the internal combustion engine detection means, and estimates the estimation result as the detection result of the nitrogen oxide detection means The nitrogen oxide processing apparatus according to claim 9, comprising means.   The internal combustion engine detection means detects at least one of a rotational speed of the internal combustion engine, a temperature of the exhaust gas, a flow rate of the exhaust gas, and a temperature of air supplied to the internal combustion engine. The nitrogen oxide processing apparatus according to claim 10. The nitrogen oxide detecting means includes
Catalyst temperature detection means for detecting the temperature of the catalyst;
Reduction efficiency calculation means for calculating the reduction efficiency when nitrogen oxides are reduced based on the detection result of the catalyst temperature detection means;
With
12. The nitrogen oxide according to claim 9, wherein the reformed fuel deriving unit derives the reformed fuel information based on the reduction efficiency calculated by the reduction efficiency calculating unit. Processing equipment. The nitrogen oxide detecting means includes
A light oil state detection means for detecting a state of the supplied light oil supplied to the fuel reformer;
Reforming efficiency calculating means for calculating reforming efficiency when the fuel reformer reforms from light oil to reformed fuel based on the detection result of the light oil state detecting means;
With
13. The nitrogen according to claim 9, wherein the reformed fuel deriving unit derives the reformed fuel information based on the reforming efficiency calculated by the reforming efficiency calculating unit. Oxide processing equipment.   The nitrogen oxide processing apparatus according to claim 13, wherein the light oil state detection means detects at least one of a temperature of the supplied light oil and a component ratio of the supplied light oil.   15. The nitrogen oxide treatment apparatus according to claim 8, wherein the catalyst is a substance containing at least silver and is supported on an alumina carrier.