JP2010106689A - Photocatalyst fuel reforming system of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocatalyst fuel reforming system of an internal combustion engine that can reform fuel responsively depending on an operating state and supply fuel with an octane value suitable for the operating state, and that can therefore control ignition time and be suitably used, for example, for an internal combustion engine using HCCI gasoline. <P>SOLUTION: A photocatalyst fuel reforming system 1 of an internal combustion engine includes an internal combustion engine 2, a fuel tank 3 for supplying fuel to the internal combustion engine 2, a light source 6 for emitting light, and a photocatalyst 7 provided to a flow path 4 for the fuel supplied from the fuel tank 3 to the internal combustion engine 2. The photocatalyst fuel reforming system 1 further includes light control means for changing a wavelength range and/or quantity of light emitted from the light source 6, and the light control means changes the wavelength range and/or quantity of the light emitted from the light source 6 based on the operating state of the internal combustion engine 2, so that the photocatalyst 7 absorbs at least a part of the light emitted from the light source to improve the octane value of the fuel. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photocatalyst fuel reforming system that reforms fuel using a photocatalyst and supplies a fuel having an octane number suitable for the operating state. In particular, the present invention relates to a photocatalytic fuel reforming system for an internal combustion engine that can control the octane number of the fuel by a fast reaction according to the operating state and can be suitably used for an internal combustion engine that performs premixed compression ignition combustion.

An internal combustion engine (Homogeneous Charge Compression Ignition, hereinafter referred to as “HCCI gasoline internal combustion engine”, which is also referred to as “HCCI gasoline internal combustion engine”) that performs premixed compression ignition combustion has low NOx and CO ₂ emissions and excellent exhaust gas. Both performance and high thermal efficiency can be achieved, achieving near ideal combustion.

  However, in the HCCI gasoline internal combustion engine, fuel is injected in an intake stroke or a compression stroke to form a premixed gas, and is ignited and burned by compression, so that the fuel is injected relatively early. For this reason, if the combustion speed of the premixed gas becomes excessive at high load or the like, pre-ignition (a phenomenon in which the mixture begins to explode during the compression stroke) may occur, and vibration may occur. As described above, the HCCI gasoline internal combustion engine has a problem in that ignition and combustion are difficult to control and the operation range is limited.

In order to control the ignition timing, many control systems such as control of intake air temperature, introduction of an internal EGR (exhaust gas recirculation) device, control of a variable compression device have been tried (Non-Patent Document 1).
Koichi Hatamura, “Possibility and Challenges of HCCI (Premixed Compression Ignition) Gasoline Engine”. Automobile Engineering Society Proceedings 20054172, VOL. 36, no. 2, (2005).

By the way, in recent years, it is known that the ignition delay of various fuels correlates to some extent with the octane number of the fuel, and it has been reported that the ignition delay tends to increase as the octane number of the fuel increases ( Non-patent document 2).
Tanaka Shigeyuki et al., "Chemical reaction kinetic study on HCCI combustion characteristics of normal heptane / isooctane mixed fuel mixture using reduced scheme (1st report)-Examination based on zero-dimensional model", Proceedings of the Society of Automotive Engineers of Japan 20004255, Vol. 35, no. 2, (2004).

  According to the said nonpatent literature 2, it has shown that there is a possibility that the ignition timing can be controlled by using a plurality of fuels having different octane numbers.

As a system that uses a plurality of fuels having different octane numbers, a system including a first fuel supply unit that supplies high octane number fuel into a combustion chamber of an internal combustion engine and a second fuel supply unit that supplies low octane number fuel is proposed. (Patent Document 1).
JP 2004-197660 A

Also, a system has been proposed that includes a fuel separation unit that separates into a plurality of types of fuels having different compositions, and selects or mixes any one of the plurality of types of fuel to supply desired combustion to the internal combustion engine. (Patent Document 2).
JP 2007-231761 A

Furthermore, a system has been proposed in which fuel is reformed using a catalytic reaction, and reformed gas and high-octane fuel are selectively used according to operating conditions (Patent Document 3). In addition, the fuel is separated and fractionated into a low-octane fuel and a high-octane fuel, and reforming is performed to increase the octane number of the low-octane fuel using a catalytic reaction. Has been proposed (Patent Document 4).
JP 2000-291499 A JP 2000-329013 A

  The catalytic reaction described in Patent Document 3 or 4 generally means a thermal catalytic reaction using thermal energy. In recent years, a photocatalytic reaction with a cleaner image using light energy such as sunlight has attracted attention, and research on the photocatalyst has been actively conducted.

When the photocatalyst absorbs light having a band gap energy or higher, electrons in the valence band are excited to the conduction band to generate holes. It is believed that active species such as hydroxy radicals and superoxide anions are generated by the movement of holes and electrons to the catalyst surface.
These active species have a very high oxidizing power and can easily oxidize and decompose organic substances. In recent years, utilizing a photocatalytic reaction, air purification, water purification, antifouling and antifogging using a photocatalyst have been put into practical use (Non-patent Document 3).
Akira Fujishima, “Ceramics”, 39, 2004, No. 1 7

Since the photocatalyst undergoes a photocatalytic reaction by the above mechanism due to light absorption, it is possible to use light energy such as sunlight with a clean image.
Thus, unlike conventional catalysts, the photocatalyst has a feature that it is not necessary to supply heat energy or the like.
However, the photocatalyst has a disadvantage that a sufficient reaction rate is not obtained. The reason for this is that light utilization efficiency is low.

At present, titanium oxide is most widely used as a photocatalyst from the viewpoint of price and chemical stability. However, titanium oxide has a high band gap of 3.2 eV and can absorb only ultraviolet light.
This ultraviolet light is only about 3% in sunlight, and in fluorescent lamps used indoors, ultraviolet light is converted into visible light by a fluorescent substance. It is hardly contained in the light that is emitted. In addition, in a vehicle such as an automobile, glass that cuts ultraviolet rays is often used, so that only visible light can be used, and ultraviolet rays are difficult to use.
Thus, when titanium oxide is used as a photocatalyst, the actual situation is that light energy higher than the band gap energy for exciting titanium oxide is not obtained.

On the other hand, visible light is contained in about 50% of sunlight, and visible light can be used indoors or in a vehicle. Therefore, a substance having a band gap excited by visible light is used as a photocatalyst. If available, the photocatalytic reaction can be used at a higher reaction rate.
Therefore, reduction of the band gap energy has been studied so that a new absorption band appears in the visible light region.

Since the energy of the conduction band and the valence band is governed by the orbit of oxygen, any orbit may be controlled in order to reduce the band gap energy.
However, it is known that when the metal side orbit is controlled, the photocatalytic activity is reduced because recombination centers of electrons and holes are generated.
Therefore, it is necessary to control the orbit after substituting with an element whose valence band energy is higher than oxygen.

Since the valence electron of the nitrogen atom has higher energy than the valence electron of the oxygen atom, the band gap energy can be reduced and visible light may be used.
For example, titanium oxide doped with nitrogen by NOx treatment or ammonia treatment (see, for example, Non-Patent Document 4) and oxynitride materials (see, for example, Patent Document 5 and Patent Document 6) have been proposed.
Shinri Sato, “What is a photocatalyst?”, Kodansha, 2004 JP 2002-066333 A JP 2004-230306 A

On the other hand, various researches and developments have been made to improve the catalytic activity itself.
For example, in order to increase the amount of adsorption of the reactants on the catalyst surface, a porous material and a photocatalyst are combined, and in order to reach the catalyst surface without deactivating the electrons and holes generated by photoexcitation, Or the powder is pulverized (see, for example, Patent Document 7). Further, in order to promote charge separation, a metal is supported (for example, see Patent Document 8).

Application research and development of photocatalysts is also thriving, and many examples of applying photocatalysts have been reported in addition to organic matter decomposition such as hydrogen generation by water splitting and dirt removal.
As such an application example, a hydrophilic mesh sheet having a photocatalyst-containing layer is installed in a greenhouse, water is allowed to flow down to the hydrophilic mesh sheet to evaporate, and the ambient temperature and humidity are controlled by heat of vaporization and vaporized water vapor. A method of adjusting is proposed (Patent Document 9).
JP 2005-013132 A

Moreover, the photocatalyst is applied not to organic matter decomposition but to organic matter synthesis. When photocatalyst is reacted using (S) -lysine (L-lysine), which is an optically active substance, as a raw material, pipecolic acid, which is a kind of cyclic amino acid, is produced. Although pipecolic acid is a raw material for pharmaceuticals, it is almost impossible to obtain it from natural products. Therefore, pipecolic acid (optically active substance) can be artificially synthesized by photocatalytic reaction (Non-patent Document 5).
Otani, “A book that understands how photocatalysts work”, Technical Review, 2003

A method of applying a photocatalyst has also been proposed in order to improve the desulfurization efficiency of fuel (Patent Document 10). In addition, there has been proposed a fuel tank in which a photocatalyst is disposed in a tank for storing fuel and the fuel in the tank is reformed by this photocatalyst (Patent Documents 11 and 12).
Japanese Patent No. 3723841 Japanese Patent Laid-Open No. 10-176615 JP 2006-307791 A

  Although there are many examples of applying catalytic reactions to fuel reforming, for example, thermal catalytic reactions progress by catalytic energy due to thermal energy. It is difficult to quality. Even when the photocatalyst is used as described above, the photocatalytic reaction proceeds in the fuel tank, so that it is difficult to reform the fuel with a fast reaction according to the operation state.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to reform a fuel by a fast reaction according to an operating state, and to provide an octane fuel suitable for the operating state. Therefore, it is possible to control the ignition timing, and for example, to provide a photocatalytic fuel reforming system for an internal combustion engine that can be suitably used for an HCCI (premixed compression ignition type) gasoline internal combustion engine. .

  As a result of intensive studies to achieve the above object, the present inventors provided a light source for irradiating light and a photocatalyst disposed in a fuel flow path supplied from a fuel tank to a combustion chamber of an internal combustion engine, It has been found that the above object can be achieved by providing light control means for changing the wavelength region and / or the amount of light emitted from the light source.

  That is, the present invention relates to an internal combustion engine, a fuel tank for supplying fuel to the internal combustion engine, a light source for irradiating light, and a photocatalyst provided in a flow passage of fuel supplied from the fuel tank to the internal combustion engine. A photocatalytic fuel reforming system for an internal combustion engine comprising: a light control means for changing a wavelength region and / or a light quantity of light emitted from the light source, wherein the light control means is an operating state of the internal combustion engine. Accordingly, the wavelength region and / or the amount of light emitted from the light source is changed so that the photocatalyst absorbs at least a part of the light emitted from the light source and improves the octane number of the fuel.

According to the present invention, the reactivity of the photocatalyst can be improved by providing the light control means for changing the wavelength region and / or the amount of light emitted from the light source in accordance with the operating state of the internal combustion engine. The reforming of the fuel can be performed so that the octane number suitable for the operating state can be obtained by a fast reaction corresponding to the operating state that changes every moment.
Thus, according to the present invention, since the fuel whose octane number is controlled according to the operating state can be supplied to the internal combustion engine, it is possible to control the ignition timing of the internal combustion engine, and it is difficult to control ignition and combustion. It can be suitably used for an HCCI gasoline internal combustion engine in which the operating range is limited.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present specification, “%” such as yield represents a mass percentage unless otherwise specified.

  FIG. 1 is a system configuration diagram showing an HCCI gasoline internal combustion engine (hereinafter referred to as “engine 2”) to which the photocatalytic fuel reforming system for an internal combustion engine of the present invention is applied.

  The photocatalytic fuel reforming system 1 includes an engine 2 and a fuel tank 3 for supplying fuel to the engine 2.

A photocatalyst reforming section 5 is provided in the flow passage 4 for supplying fuel from the fuel tank 3 to the engine 2. The photocatalyst reforming section 5 is provided with a light source 6 that emits light and a photocatalyst 7 at a site that can absorb at least part of the light emitted from the light source 6.
In addition, light emitted from the light source 5 is transmitted through at least a part of the side wall of the flow passage 4 constituting the photocatalyst reforming section 5, and the photocatalyst 7 can absorb at least a part of the transmitted light. As described above, the light transmissive substrate 8 is arranged.

  Detection signals from various sensors (not shown) are input to the control unit (hereinafter referred to as “ECU”) 10 of the engine 2 in order to control the engine 2. The various sensors include an engine rotation sensor that detects the engine rotation speed Ne, an accelerator opening sensor that detects an accelerator opening (required load) APO, and the operation state parameter based on the results detected by these sensors. (Operation status signal) is monitored.

Further, the ECU 10 outputs a signal to the light source 6 based on the operation state signal of the engine 2, so that the photocatalyst 7 is activated by the light emitted from the light source 6 to improve the octane number of the fuel. The wavelength region and / or the amount of light irradiated to the photocatalyst 7 are changed.
As described later, the light source 6 can selectively change a wavelength region of light emitted from the light source by using a plurality of light sources 6 that emit light having different wavelength regions, and is supplied to the light source. It is preferable to use one that can change the amount of light emitted from the light source 6 by changing the current or voltage.

Next, the photocatalyst will be described.
The photocatalyst 7 is only required to be disposed at a position capable of absorbing light emitted from the light source 6, and may be suspended in the fuel flowing through the flow passage 4, or the piping constituting the fuel flow passage 4. It may be fixed to the inner wall.
As long as the photocatalyst 7 is a part capable of absorbing the light emitted from the light source 6, the photocatalyst 7 is a part of the fuel tank 3 that is a part of the fuel flow passage 4 supplied from the fuel tank 3 into the combustion chamber of the engine 2. It may be fixed to an inner wall including the bottom surface.

  The photocatalyst 7 absorbs light irradiated from the light source 6 and is excited to release active species, whereby a low octane number substance (for example, n-hexane) in the fuel is converted into a high octane number substance (for example, 2-methylpentane). , Methylcyclopentane, cyclohexane, etc.).

The photocatalyst 7 is preferably provided with a plurality of types of photocatalysts having different band gap energies.
A plurality of types of photocatalysts having different band gap energies may be disposed one by one at different locations, or a mixture of a plurality of types of photocatalysts at a predetermined ratio (for example, equal amount) may be disposed at the same location. .

When a plurality of types of photocatalysts having different band gap energies are provided, the octane number of the fuel can be controlled by changing the wavelength region of the irradiated light.
A photocatalyst having a relatively wide band gap absorbs light on the short wavelength side and converts a substance having a low octane number in the fuel into a substance having a high octane number. On the other hand, a photocatalyst having a relatively narrow band gap also absorbs light on a longer wavelength side and converts a substance having a low octane number in the fuel into a substance having a high octane number.

  That is, when a photocatalyst with a relatively narrow band gap and a photocatalyst with a relatively wide band gap are provided, only the photocatalyst with a narrow band gap is activated when light on the long wavelength side is irradiated. On the other hand, when the light on the short wavelength side is irradiated, both the photocatalyst having a wide band gap and the photocatalyst having a narrow band gap are activated.

  Thus, by changing the wavelength region of the light irradiated to the photocatalyst, the reactivity of the photocatalyst can be controlled, and the octane number of the fuel reformed by the activated photocatalyst can be controlled.

When the octane number of the fuel is controlled by the photocatalytic reforming unit 5 and a fuel having an octane number suitable for the operating state is supplied to the engine 2, the ignition delay period changes, and the ignition timing can be controlled.
For example, when the high-octane fuel whose octane number has been improved in the photocatalytic reforming unit 5 is supplied to the engine 2 in the high-load operation state, the ignition delay period becomes long, and pre-ignition in the HCCI gasoline internal combustion engine is caused. By avoiding the ignition timing, the ignition timing can be controlled.

The photocatalyst 7 is at least selected from the group consisting of titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), tantalum oxide (Ta ₂ O ₃ ), niobium oxide (Nb ₂ O ₃ ), and cerium oxide (CeO ₂ ). One type is preferable.

For example, the band gap energy of TiO ₂ is 3.2 eV, the band gap energy of ZrO ₂ is 5.0 eV, and the band gap energy of Nb ₂ O ₃ is 3.0 eV. The wavelength of light having an energy of 3.0 eV is 413 nm, and the wavelength of light having an energy of 5.0 eV is 248 nm.
When two types of photocatalysts of TiO ₂ and ZrO ₂ are provided, when irradiating light having a longer wavelength of 413 nm or more, only TiO ₂ is activated, and when irradiating light having a shorter wavelength of 248 nm or less, TiO ₂ And ZrO ₂ are both activated.

FIG. 2 is a graph showing the relationship between the fuel conversion rate (octane number) and wavelength when two types of photocatalysts (ZrO ₂ ; 5.0 eV, TiO ₂ ; 3.2 eV) having different band gaps are provided. .
As shown in FIG. 2, for example, when light having a long wavelength side of 413 nm or more is irradiated, only TiO _{2 having} a relatively large band gap absorbs light having a long wavelength side, and a substance having a low octane number in the fuel. Is converted to a substance with a high octane number.
On the other hand, for example, when light with a short wavelength of 248 nm or more is irradiated, ZrO ₂ with a small band gap and TiO ₂ with a large band gap are activated by absorbing light with a short wavelength, and the conversion rate of fuel is increased. Increases the octane number.

Next, control of the photocatalytic reforming system according to one embodiment (first embodiment) of the present invention will be described.
FIG. 3 is a flowchart showing the processing operation of the photocatalytic fuel reforming system of the engine 2 according to the first embodiment of the present invention.
In FIG. 3, in S1, after ignition is performed in the combustion chamber of the engine 2 by an ignition device (not shown), the operation is performed based on the engine speed, request load signal, etc. input from various sensors (not shown). Read state.
In S2, it is determined whether or not the torque of the engine 2 has reached a predetermined value Nm1 based on the value read in S1.
When Nm1 is reached, the process proceeds to S3 photocatalytic reforming control. If Nm1 has not been reached, it is determined again whether the torque of the engine 2 has reached Nm1 to a predetermined value.

In S3, photocatalytic reforming control is performed.
In the photocatalyst reforming control performed in S3, the degree of activation of the photocatalyst is changed by changing the wavelength region and / or the amount of light emitted from the light source by the light control unit according to the operating state of the engine 2. Change the conversion rate of the fuel from low octane number to high octane number.

  When the ECU 10 determines that the high load operation is performed based on the values read by the engine rotation sensor and the accelerator opening sensor, the ECU 10 outputs a signal to the light source 6, and the wavelength region of the light emitted from the light source 6 and / or Change the amount of light to increase the degree of activation of the photocatalyst and improve the octane number of the fuel.

In S4, the ECU 10 detects the in-cylinder pressure based on signals indicating the operating characteristics of the intake valve and the exhaust valve of the engine 2, and determines whether or not the in-cylinder pressure has reached a predetermined value P1. Further, the ECU 10 determines whether or not the engine speed has reached a predetermined value r1 based on an engine speed detection signal or the like input from various sensors (not shown).
When the in-cylinder pressure does not reach P1, or when the engine rotor does not reach r1, the photocatalytic reforming control is repeated.
When the in-cylinder pressure has reached P1 and the engine speed has reached r1, this control is terminated.

FIG. 4 is a graph showing the relationship between the engine speed and torque (load) and the wavelength of light applied to the photocatalyst, where the horizontal axis indicates the engine speed and the vertical axis indicates the torque.
A photocatalyst having a band gap of about 3.2 eV cannot absorb visible light on the long wavelength side of 413 nm or more, and can absorb only ultraviolet light on the short wavelength side. In a high load operation state with a large torque, a high octane number fuel is required.
As shown in FIG. 4, in order to reform to a high octane fuel required in a high-load operation state, it is necessary to irradiate a lot of light on the short wavelength side where the photocatalyst is activated.

Next, a photocatalytic reforming system according to an embodiment (second to eighth embodiments) of the present invention will be described.
FIG. 5 is a schematic diagram showing the configuration of the photocatalytic reforming unit 5 in the second embodiment of the present invention.
As shown in FIG. 5, in this example, the photocatalytic reforming unit 5 irradiates a light source 6 </ b> A that emits light on a long wavelength (for example, 410 to 420 nm) side and light on a short wavelength (for example, 245 to 250 nm) side. A light source 6B is provided. As the photocatalyst 7, both a photocatalyst having a narrow band gap and a photocatalyst having a wide band gap are provided.

  Based on signals input from various sensors, the ECU selectively selects the light source 6B that emits light on the short wavelength side, for example, in the case of a high load and high speed operation state, according to the operation state of the engine. A signal for lighting is output, and the light source 6B is turned on.

  When light is irradiated from the light source 6B, the photocatalyst 7 is activated to convert a substance having a low octane number in the fuel into a substance having a high octane number. When short-wavelength light is irradiated from the light source 6B, both the photocatalyst with a narrow band gap and the photocatalyst with a wide bandgap that absorb this short-wavelength light are activated, and the conversion rate to a substance with a high octane number increases. The octane number of the fuel is improved.

  When high octane number fuel is supplied from the photocatalytic reforming unit 5 to the engine 2 in a high load operation state, the ignition delay period becomes longer, avoiding problems such as premature ignition in the HCCI gasoline internal combustion engine, and the ignition timing Can be controlled.

  On the other hand, in the low-load, low-speed operation state, the ECU is less likely to supply high-octane fuel, and therefore outputs a signal for selectively lighting the light source 6A that emits light on the long wavelength side. The light source A is turned on.

  When long wavelength light is irradiated from the light source 6A, only a photocatalyst with a narrow band gap that absorbs this long wavelength light is activated, and a photocatalyst with a wide band gap that does not absorb this long wavelength light is not activated, The conversion rate of the fuel decreases, and the octane number of the fuel increases slightly.

  In low-load operation conditions, the premixed gas combustion rate is unlikely to be excessive and premature ignition is unlikely to occur, so there is little need to change the ignition delay period and even if fuel with a relatively low octane number is supplied The ignition timing can be easily controlled.

FIG. 6 is a schematic diagram showing the configuration of the photocatalytic reforming unit 5 in the third embodiment of the present invention.
As shown in FIG. 6, in this example, the light source 6 provided in the photocatalytic reforming unit 5 transmits light in a specific wavelength region and cuts off light in other wavelength regions (optical filter). 9 is provided. As the photocatalyst 7, both a photocatalyst having a narrow band gap and a photocatalyst having a wide band gap are provided.

  Based on the signals input from the various sensors, the ECU emits light on the short wavelength side (for example, the wavelength region is 250 nm or less) in the operating state of a high load and high speed rotation according to the operating state of the engine. A signal for selectively lighting the light source 6 provided with the transmission cutoff filter 9 is output, and the light source 6 is turned on.

The photocatalyst 7 is irradiated only with light having a short wavelength (for example, a wavelength region of 250 nm or less) that has passed through the cutoff filter 9.
When light on the short wavelength side is irradiated from the light source 6 through the cut-off filter 9, both the photocatalyst with a narrow band gap and the photocatalyst with a wide band gap that absorb this short wavelength light are activated, and the octane number is high. The conversion rate to the substance is increased, and the octane number of the fuel is improved.

  On the other hand, in the low-load, low-speed operation state, the ECU needs to supply high-octane fuel, so the light on the short wavelength side (for example, the wavelength region is 250 nm or less) is cut and the long wavelength side is cut. A signal for selectively lighting the light source 6 provided with the cutoff filter 9 that transmits light (for example, the wavelength region exceeds 250 nm) is output, and the light source 6 is turned on.

The photocatalyst 7 is irradiated only with light on the long wavelength side (for example, the wavelength region is about 251 to 450 nm) that has passed through the cutoff filter 9.
When light of a long wavelength side is irradiated from the light source 6 through the cut-off filter 9, only a catalyst having a narrow band gap that absorbs light of this long wavelength is activated, and a catalyst having a wide band gap is not activated. The conversion rate of the fuel is reduced, and the octane number of the fuel is slightly increased.

  If it is possible to change the wavelength range of light irradiated from the light source to the photocatalyst by the light control means, the conversion rate of the fuel can be controlled by the photocatalytic reaction, and the octane number of the fuel can be controlled. According to the photocatalyst fuel reforming system of this example, the fuel whose octane number is controlled can be supplied with a fast reaction according to the operating state of the engine, and the ignition timing can be controlled.

FIG. 7 is a schematic diagram showing the configuration of the photocatalytic reforming unit 5 in the fourth embodiment of the present invention.
As shown in FIG. 7, in this example, a plurality of light sources 6 are provided in the photocatalytic reforming unit 5, and a current (A) is supplied from a power source 11 to each light source 6 and a voltage (V) is applied.

  The ECU outputs a signal for increasing the current value and / or the voltage value according to the operating state of the engine, for example, in the case of an operating state of high load and high speed rotation, and increases the amount of light emitted from the light source 6.

FIG. 8 is a graph showing the relationship between the fuel conversion rate (octane number) of the photocatalyst and the amount of light (mW / cm ² ) emitted from the light source 6.
As shown in FIG. 8, the greater the amount of light, the more the photocatalyst is activated and the higher the fuel conversion rate.

  Therefore, in a high-load operation state, when the amount of light emitted from the light source 6 is controlled to be large, the photocatalyst is activated, the fuel conversion rate (octane number) is increased, and the high-octane fuel is engineered. To be supplied. The ignition delay period is extended by the high-octane fuel supply, and the ignition timing can be controlled while avoiding problems such as pre-ignition in the HCCI gasoline internal combustion engine.

  On the other hand, in the low-load, low-speed operation state, the need for supplying high-octane fuel is low, so the ECU outputs a signal for increasing the current value and / or voltage value and is emitted from the light source 6. Reduce the amount of light

  As shown in FIG. 8, when the amount of light decreases, the fuel conversion rate decreases. In the low-load operation state, the premixed gas combustion rate is unlikely to be excessive and premature ignition is unlikely to occur, so there is little need to lengthen the ignition delay period and even if fuel with a relatively low octane number is supplied The ignition timing can be easily controlled.

  The second embodiment or the third embodiment is combined with the fourth embodiment to change the wavelength region and the amount of light emitted from the light source, thereby controlling the fuel conversion rate (octane number) by the photocatalyst. The ignition timing may be controlled. For example, light sources that irradiate light in different wavelength regions may be selectively turned on (second embodiment), and the current value and / or voltage value of each light source may be changed (fourth embodiment). Further, for example, a light source provided with a cut-off filter that transmits light in different wavelength regions is selectively turned on (third embodiment), and the current value and / or voltage value of each light source is selectively changed. (4th Embodiment).

FIG. 9 is a schematic view showing the configuration of the photocatalytic reforming unit 5 in the fifth embodiment of the present invention.
As shown in FIG. 9, in this example, a plurality of light sources 6 are provided in the photocatalyst reforming unit 5, and each light source 6 is dimmed with different transmittances that absorb a part of the light emitted from the light source 6 ( Neutral Density (ND) filters 12A and 12B are provided. In this example, among the plurality of light sources 6, half of the light sources are provided with a neutral density filter 12A having a high transmittance, and the other half of the light sources are provided with a neutral density filter 12B having a low transmittance.

  Based on signals input from various sensors, the ECU selectively turns on the light source provided with the neutral density filter 12A having a high transmittance, for example, in the case of a high load operating state, according to the operating state of the engine. A signal is output and the light source 6 is turned on.

  The photocatalyst 7 is irradiated with light having a high photon number and a large amount of light from the light source 6 through a neutral density filter 12A having a high transmittance. The photocatalyst 7 is activated by absorbing this light having a large amount of light, and the fuel is reformed to improve the octane number of the fuel. When high-octane fuel is supplied from the photocatalytic reforming unit 5 to the HCCI gasoline internal combustion engine, the ignition delay period becomes longer, and the ignition timing can be controlled.

  On the other hand, in the low-load, low-speed operation state, the ECU is less likely to supply high-octane fuel, so a signal for selectively lighting the light source provided with the light-reducing filter 12B with low transmittance is provided. The light source 6 is turned on.

The photocatalyst 7 is irradiated with light having a low photon number and a small amount of light from the light source 6 through a neutral density filter 12B having a low transmittance. The photocatalyst 7 is activated by absorbing light with a small amount of light, the conversion rate to a substance having a low octane number is lowered, and the octane number of the fuel is slightly increased.
In the low-load operation state, the combustion speed of the premixed gas is unlikely to be excessive and pre-ignition is unlikely to occur, so that the ignition timing can be easily controlled even when fuel having a relatively low octane number is supplied.

  The second embodiment or the third embodiment is combined with the fifth embodiment to change the wavelength region and the amount of light emitted from the light source, thereby controlling the fuel conversion rate (octane number) by the photocatalyst. The ignition timing may be controlled. For example, a light-reducing filter (fifth embodiment) having a different transmittance may be provided in a light source (second embodiment) that irradiates light in different wavelength regions, and each light source may be selectively turned on. In addition, for example, each of the plurality of light sources is provided with a cut-off filter (third embodiment) that transmits light in different wavelength regions and a neutral density filter (fifth embodiment) having different transmittances. You may make it light selectively.

In the photocatalyst reforming unit 5 shown in FIG. 1 according to the first embodiment of the present invention, the light source 6 may be used as a heating device for heating the photocatalyst 7.
By supplying heat energy generated from the light source 6 to the photocatalyst 7, when the light for activating the photocatalyst 7 is irradiated, the reactivity of the photocatalyst 7 is greatly improved, and it responds quickly to the signal output from the ECU 10. Thus, the octane number of the fuel can be improved.

FIG. 10 is a configuration diagram showing an outline of the photocatalytic reforming unit 5 in the sixth embodiment of the present invention.
As shown in FIG. 10, the photocatalyst reforming unit 5 of this example is provided with a light source 13 that emits infrared rays as a heat transfer device for transferring heat to the photocatalyst 7.
By supplying thermal energy to the photocatalyst 7 from the light source 13 that emits infrared rays, the reactivity of the photocatalyst 7 can be greatly improved when the photocatalyst 7 is activated by absorbing light in a specific wavelength region. The octane number of the fuel can be improved by a fast reaction according to the operating state of the engine 2.

FIG. 11 is a configuration diagram showing an outline of the photocatalytic reforming unit 5 in the seventh embodiment of the present invention.
As shown in FIG. 11, the photocatalyst reforming unit 5 of this example is provided with a heat transfer pipe 14 that uses exhaust heat exhausted from the engine 2 as a heat transfer device for transferring heat to the photocatalyst 7. Yes.
By supplying the heat energy of the exhaust heat to the photocatalyst 7 through the heat transfer pipe 14, the reactivity of the photocatalyst 7 can be greatly improved when the photocatalyst 7 is activated, depending on the operating state of the engine 2. The fast reaction can improve the octane number of the fuel.

FIG. 12 is a configuration diagram showing an outline of the photocatalytic reforming unit 5 in the eighth embodiment of the present invention.
As shown in FIG. 12, the photocatalyst reforming unit 5 of this example is provided with a heater 15 as a heat transfer device for transferring heat to the photocatalyst 7. The heater 15 is disposed so that heat can be transferred to the photocatalyst 7 disposed on the inner wall of the flow passage 4.
By supplying the heat energy of exhaust heat to the photocatalyst 7 through the heater 15, the reactivity of the photocatalyst 7 can be greatly improved when the photocatalyst 7 is activated, and fast according to the operating state of the engine 2. The reaction can improve the octane number of the fuel.

FIG. 13 is a system configuration diagram showing a photocatalytic fuel reforming system for an internal combustion engine according to the ninth embodiment of the present invention.
As shown in FIG. 13, the photocatalytic fuel reforming system 1 of this example is provided with a storage tank 16 that stores fuel whose octane number is improved by the photocatalytic reforming unit 5.
By storing the fuel whose octane number is improved in the storage tank 16 in advance, for example, in a high-load operation state, a high amount of high-octane fuel can be supplied from the storage tank 16 to the engine 2.
As described above, if a large amount of high octane fuel stored after being reformed in advance can be supplied to the engine 2 in accordance with the operating state, the responsiveness is improved, and the ignition timing immediately corresponding to the operating state is improved. Control becomes possible.

The first to ninth embodiments may be selected and used in combination.
For example, the reactivity of the photocatalyst 7 is greatly improved by providing the photocatalyst reforming unit 5 according to the first to fifth embodiments with the heating device shown in any of the sixth to ninth, so that the operating state of the engine 2 is improved. It is possible to improve the octane number of the fuel with a fast reaction according to the above.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

Example 1
As a photocatalyst, commercially available titanium oxide (P-25, TiO ₂ ; band gap energy 3.0 eV), niobium oxide (Nb ₂ O ₃ : band gap energy 3.4 eV), tantalum oxide (Ta ₂ O ₃ : band gap energy) 4.0 g) and 0.2 g of zirconium oxide (ZrO ₂ : band gap energy 5.0 eV) (0.02 g of titanium oxide (P-25)) were used.
N-hexane was used as the fuel to be reformed.
Each photocatalyst and 1.5 mL of n-hexane were charged into a beaker and stirred using a stirrer to obtain a suspension in which the photocatalyst was suspended in n-hexane.
The reaction vessel containing the suspension was irradiated with light having a changed wavelength region from a visible light (360 to 400 nm) region to a short wavelength region of 350 nm using an ultrahigh pressure Hg lamp as a light source. The irradiation time was 5 hours.
As described above, when the photocatalyst was irradiated with light having a changed wavelength region, the activated photocatalyst was titanium oxide and niobium oxide.
Further, when the photocatalyst was irradiated with light having a changed wavelength region as described above, a part of n-hexane in the fuel was converted (isomerized) into methylpentane, methylcyclopentane, and cyclohexane. The conversion rate (octane number) of the fuel (n-hexane) was calculated by the following measuring method. The margin for improving the octane number of the fuel in Example 1 was about 6.

[Measurement method of octane number]
The amount of the product contained in the fuel was measured by GC-FID (Gas chromatograph-Flame ionization detector) and GC-MS (Gas chromatograph-Mass spectrometer).
As a result of the measurement, methylpentane, methylcyclopentane, and cyclohexane were detected in the fuel, and it was confirmed that isomerization, cyclization, and partial oxidation occurred although n-hexane was a minimal amount.
Although the octane number of n-hexane is as low as 24.8, the octane number of 2-methylpentane obtained by isomerization is 73.4, the octane number of cyclohexane is 83.0, and the octane number of methylcyclopentane is 91.3. And high.
Table 1 shows the conversion rates (yield:%) of 2-methylpentane, cyclohexane and methylcyclopentane obtained by isomerizing n-hexane with each catalyst. Based on Table 1 and the octane number, the allowance for increasing the octane number in each example and comparative example was calculated.

(Example 2)
Light was irradiated in the same manner as in Example 1 except that the wavelength region was changed from the visible light (360 to 400 nm) region to a short wavelength region of 300 nm.
As described above, when the photocatalyst was irradiated with light having a changed wavelength region, the activated photocatalyst was titanium oxide, niobium oxide, and tantalum oxide.
The margin for improving the octane number of the fuel of Example 2 was about 8.

(Example 3)
Light was irradiated in the same manner as in Example 1 except that the wavelength region was changed from the visible light (360 to 400 nm) region to a short wavelength region of 230 nm.
As described above, when the photocatalyst was irradiated with light having a changed wavelength region, the activated photocatalyst was titanium oxide, niobium oxide, tantalum oxide, and zirconium oxide.
The margin for improving the octane number of the fuel of Example 3 was about 12.

(Comparative example)
The light was irradiated in the same manner as in Example 1 except that the wavelength region was 400 nm and the wavelength region was not changed.
As described above, when the photocatalyst was irradiated with light in a certain wavelength region (400 nm), the activated photocatalyst was only titanium oxide.
The margin for improving the octane number of the fuel of the comparative example was about 4.

FIG. 14 is a graph showing the relationship between the wavelength range of irradiated light and the allowance for increasing the octane number by the photocatalyst in Examples 1 to 3 and Comparative Example.
As shown in FIG. 14, when the photocatalyst performs control to change the wavelength region of the light emitted from the light source so as to absorb at least part of the light emitted from the light source and improve the octane number of the fuel, The octane number of the fuel has been improved.
From this result, the reactivity of the photocatalyst is improved according to the operation state changing every moment by providing the light control means for changing the wavelength region of the light emitted from the light source according to the operation state of the internal combustion engine. It was confirmed that the octane number of the fuel could be controlled and the ignition timing could be controlled.

1 is a system configuration diagram showing a photocatalytic fuel reforming system for an internal combustion engine in a first embodiment. Two kinds of photocatalytic conversion of fuel obtained when a _(ZrO 2, TiO ₂₎ (octane number) is a graph showing the relationship between the wavelength. It is a flowchart which shows the processing operation of the photocatalyst fuel reforming system of the internal combustion engine of 1st Embodiment. It is a graph which shows the relationship between an engine speed and torque (load), and the wavelength of the light irradiated to a photocatalyst. It is a block diagram which shows schematically the photocatalyst modification part in 2nd Embodiment. It is a block diagram which shows schematically the photocatalyst modification part in 3rd Embodiment. It is a block diagram which shows schematically the photocatalyst modification part in 4th Embodiment. It is a graph which shows the relationship between the conversion rate (octane number) of the fuel by a photocatalyst, and light quantity (mW / cm < ² >). It is a block diagram which shows schematically the photocatalyst modification part in 5th Embodiment. It is a block diagram which shows schematically the photocatalyst modification part in 6th Embodiment. It is a block diagram which shows schematically the photocatalyst modification part in 7th Embodiment. It is a block diagram which shows schematically the photocatalyst modification part in 8th Embodiment. It is a system block diagram which shows the photocatalyst fuel reforming system of the internal combustion engine in 9th Embodiment. It is a graph which shows the relationship of the wavelength range of the irradiated light in Examples 1-3 and a comparative example, and the improvement margin of the octane number by a photocatalyst.

Explanation of symbols

1 Photocatalytic fuel reforming system for internal combustion engine 2 HCCI gasoline internal combustion engine (engine)
DESCRIPTION OF SYMBOLS 3 Fuel tank 4 Flow path 5 Photocatalyst fuel reforming part 6 Light source 6A, 6B Light source 7 Photocatalyst 8 Light transmissive substrate 9 Cut-off filter 10 ECU
DESCRIPTION OF SYMBOLS 11 Power supply 12A, 12B Neutral density filter 13 Light source which irradiates infrared rays 14 Heat transfer piping 15 Heater 16 Storage tank

Claims (13)

An internal combustion engine comprising: an internal combustion engine; a fuel tank for supplying fuel to the internal combustion engine; a light source for irradiating light; and a photocatalyst provided in a flow path of fuel supplied from the fuel tank to the internal combustion engine. A photocatalytic fuel reforming system,
A light control means for changing the wavelength region and / or the amount of light emitted from the light source;
The light control means is configured to reduce the light emitted from the light source so that the photocatalyst absorbs at least part of the light emitted from the light source and improves the octane number of the fuel according to the operating state of the internal combustion engine. A photocatalytic fuel reforming system for an internal combustion engine characterized by changing a wavelength region and / or a light quantity.   2. The photocatalytic fuel reforming system for an internal combustion engine according to claim 1, wherein the internal combustion engine is an internal combustion engine that performs premixed compression ignition combustion.   The photocatalyst fuel reforming system according to claim 1 or 2, wherein a plurality of types of photocatalysts having different band gap energies are provided. Provide multiple light sources that emit light in different wavelength regions,
The said light control means changes the wavelength range of the light irradiated from the said light source selectively using these light sources according to the driving | running state of the said internal combustion engine. 4. The photocatalytic fuel reforming system for an internal combustion engine according to any one of 3 above. A light source having an optical filter that transmits light in a specific wavelength region, and a light source not having the optical filter,
The light control means selectively uses a light source having the optical filter or a light source not having the optical filter according to an operating state of the internal combustion engine, and sets a wavelength region of light emitted from the light source. The photocatalytic fuel reforming system for an internal combustion engine according to any one of claims 1 to 3, wherein the system is changed.   The said light control means changes the electric current value supplied to the said light source, and / or the voltage value of the voltage applied to the said light source, and increases / decreases a light quantity, The one of Claims 1-5 characterized by the above-mentioned. A photocatalytic fuel reforming system for an internal combustion engine according to one item.   6. A plurality of neutral density filters with different transmittances are provided, and the light control means selectively uses the neutral density filters with different transmittances to increase or decrease the amount of light. The photocatalytic fuel reforming system according to one of the items.   The photocatalyst fuel reforming system according to any one of claims 1 to 7, further comprising a heat transfer device that transfers heat to the photocatalyst.   The photocatalyst fuel reforming system according to claim 8, wherein the heat transfer device is a light source that irradiates the photocatalyst with infrared rays.   9. The photocatalyst fuel modification according to claim 8, wherein the heat transfer device is a piping device for supplying heat energy, wherein the heat transfer device is a piping device for transmitting exhaust heat discharged from the internal combustion engine. Quality system.   9. The photocatalytic fuel reforming system according to claim 8, wherein the heat transfer device is a heating device that heats the photocatalyst.   The photocatalyst is at least one selected from the group consisting of titanium oxide, zirconium oxide, tantalum oxide, niobium oxide, and cerium oxide, according to any one of claims 1 to 11, Photocatalytic fuel reforming system.   The photocatalyst fuel reforming system according to any one of claims 1 to 12, further comprising a storage tank for storing fuel whose octane number is improved by a photocatalyst.

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