JP2004077131A - Fuel concentration detection device for composite fuel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the concentration of each of component fuel of a gasified composite fuel with a simple constitution mountable on a vehicle. <P>SOLUTION: This fuel concentration detection device has a luminescent member 88 as a light source to emitting light with a plurality of wavelength, a reflector 96 to reflect the light emitted from the luminescent member 88 and passing through the gasified composite fuel flowing in the inside of a conduit 82, a spectrograph 98 to divide the light reflected by the reflector 96 and passing through the gasified composite fuel, optical filters 110-114 to respectively pass the light of specific wavelength, photodiodes 90-94 to receive the light passing through the optical filter and to output an electric signal of voltage It corresponding to its strength and an electric circuit 126 to control the photodiodes, and the electric circuit 126 computes the concentration of the composite fuel in accordance with the ratio It/Io of output voltage concerning each of the composite fuel by specifying the output voltage at the time when the concentration is zero as Io. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a gasification composite fuel comprising a plurality of hydrocarbon fuels, and more particularly, to a fuel concentration detection device for a gasification composite fuel.
[0002]
[Prior art]
For example, as described in Japanese Patent No. 2748245, when a composite fuel of a gaseous fuel such as natural gas and a liquid fuel such as butane is used, the composite fuel in a liquid state is taken out from the tank and used. As the volume of the liquid fuel in the tank gradually decreases and the volume of the gaseous composite fuel gradually increases, the gaseous fuel dissolved in the liquid fuel with the increase in the volume of the gaseous composite fuel in the tank increases. The state gradually changes to gas. Therefore, as the removal of the composite fuel in the liquid state progresses, the fuel property (component ratio) of the removed fuel gradually changes.
[0003]
For example, FIG. 12 shows a case where a fuel in a liquid state is taken out from a fuel tank storing a composite fuel composed of 70% methane (gas) and 30% butane (liquid) in a molar ratio, and the internal combustion engine is operated in a steady state. 2 shows the relationship between the pressure in the fuel tank and the molar ratio (%) of butane in the fuel. As shown in FIG. 12, as the liquid fuel is taken out of the tank and used, the amount of methane dissolved in the liquid butane gradually decreases, so that the pressure in the fuel tank becomes about 6 MPa. It can be seen that the ratio of butane gradually increases, and when all the liquid fuel is consumed and only the gas in the fuel tank becomes gas, the molar ratio of butane in the fuel rapidly decreases.
[0004]
Thus, when the fuel properties change, the stoichiometric air-fuel ratio during engine operation also changes.Therefore, in order to operate the internal combustion engine efficiently and reduce exhaust emissions, the It is necessary to change the air-fuel ratio optimally. Therefore, it is necessary to sequentially detect the concentration of the component fuel of the composite fuel and to sequentially control the fuel supply amount to the internal combustion engine according to the detection result.
[0005]
[Problems to be solved by the invention]
However, the above-mentioned patent publication discloses that the fuel properties change as described above even when the composite fuel is taken out and used in a liquid state, and that the fuel supply to the internal combustion engine is sequentially controlled in accordance with the change. No method or apparatus for sequentially detecting the concentration of the component fuel is described, and thus the method and apparatus described in the above-mentioned patent publications have room for improvement in this respect.
[0006]
As one of the hydrocarbon fuel concentration detection devices, Japanese Society of Mechanical Engineers Proceedings No. Pages 135 and 136 of No. 015-1 are a concentration detecting apparatus utilizing an infrared absorption method, wherein one light source for irradiating infrared light of a single wavelength and a hydrocarbon fuel irradiated from the light source are provided. A light receiving means for receiving the light passing therethrough and outputting a signal corresponding to the intensity of the received infrared light, and a calculating means for calculating the concentration of the hydrocarbon fuel based on the signal output from the light receiving means A detection device is described.
[0007]
However, this concentration detection device is a device intended for measurement in a laboratory, and according to this concentration detection device, it is possible to detect the overall concentration of a gasified composite fuel composed of a plurality of hydrocarbon fuels, This concentration detecting device cannot detect the concentration of each component fuel, and cannot be applied to the case where a gasified composite fuel is used as fuel for vehicles such as automobiles.
[0008]
The present invention has been made in view of the above-described problems in the case where a gasified combined fuel composed of a plurality of hydrocarbon fuels is used, and a main object of the present invention is to solve the problem of the components of the gasified combined fuel. By utilizing the light absorption phenomenon for light of a plurality of specific wavelengths according to the light absorption characteristics of the fuel, the concentration of each component fuel of the gasified composite fuel can be detected with a simple configuration that can be mounted on vehicles. is there.
[0009]
[Means for Solving the Problems]
According to the present invention, there is provided a fuel concentration detecting device for a gasified composite fuel comprising a plurality of hydrocarbon fuels, the light source for irradiating light having a plurality of wavelengths. A plurality of light receiving means for receiving light emitted from the light source and passing through the gasified composite fuel, and outputting a signal corresponding to the intensity of the light of the specific wavelength received, and a signal output from the plurality of light receiving means. And a calculating means for calculating the fuel concentration based on the fuel concentration.
[0010]
According to the present invention, in order to effectively achieve the above-mentioned main object, in the configuration of the above-mentioned claim 1, the light irradiated from the light source and passed through the gasified composite fuel is spectrally separated for each light receiving means. It is configured so as to include a spectroscopic unit that performs the above-described operation (the configuration of claim 2).
[0011]
Further, according to the present invention, in order to effectively achieve the above-described main object, in the above-described configuration of claim 1 or 2, each of the light receiving means includes a filter for passing light of a specific wavelength, and a light passing through the filter. And a light-to-electrical conversion element for converting the converted light into an electric signal of a voltage corresponding to the intensity of the light.
[0012]
Further, according to the present invention, in order to effectively achieve the above-described main object, in the above-described claims 1 to 3, the gasified composite fuel is fuel flowing through a fuel passage, and A branch passage is connected and connected at an upstream end and a downstream end, and the fuel concentration detecting device is configured to be provided in the branch passage.
[0013]
According to the present invention, in order to effectively achieve the above-mentioned main object, in the configuration of the above-mentioned claim 4, a gasified composite fuel is heated in the branch passage upstream of the fuel concentration detection device. In this case, a heating means for evaporating the liquid phase is provided.
[0014]
According to the present invention, in order to effectively achieve the above-mentioned main object, in the above-mentioned constitutions of claims 1 to 5, light emitted from the light source passes through the irradiation light transmission window to the branch passage. While passing through the gasified composite fuel flowing through, and receiving light by the light receiving means through a light transmitting window for light receiving, allowing the light transmitting window for irradiation and the light transmitting window for light receiving to pass light. Further, a cover for suppressing the flow of the gasified composite fuel from directly hitting the irradiation light transmitting window and the light receiving light transmitting window is provided (the configuration of claim 6).
[0015]
According to the present invention, in order to effectively achieve the above-described main object, in the above-described claims 4 to 6, the light source and the light-receiving means are arranged on one side of the branch passage, On the other side of the branch passage, a reflecting mirror is provided which reflects light emitted from the light source and passed through the gasified composite fuel to the light receiving means via the gasified composite fuel (claim). Configuration of item 7).
[0016]
Further, according to the present invention, in order to effectively achieve the above-mentioned main object, in the constitution according to any one of claims 1 to 7, the gasified composite fuel comprises methane, propane and butane, and Comprises light receiving means for detecting methane concentration, light receiving means for detecting propane concentration, and light receiving means for detecting butane concentration, wherein the light receiving means for detecting methane concentration receives light having a wavelength of 8.1 ± 0.1 μm; The concentration detecting light receiving means receives light having a wavelength of 8.6 ± 0.1 μm, 9.5 ± 0.2 μm, or 11.1 ± 0.2 μm. It is configured to receive light having a wavelength of 2 ± 0.1 μm, 6.3 ± 0.1 μm, or 10.5 ± 0.5 μm (claim 8).
[0017]
Further, according to the present invention, in order to effectively achieve the above-mentioned main object, in the constitution of claims 1 to 7, the gasified composite fuel comprises methane and propane, and the light receiving means comprises methane. The light receiving means for detecting methane concentration receives light having a wavelength of 8.1 ± 0.1 μm, and the light receiving means for detecting propane concentration comprises 6.6. ± 0.1 μm, 6.9 ± 0.5 μm, 7.2 ± 0.5 μm, 8.6 ± 0.1 μm, 9.5 ± 0.2 μm, any wavelength of 11.1 ± 0.2 μm It is configured to receive light (the configuration of claim 9).
[0018]
Further, according to the present invention, in order to effectively achieve the above-mentioned main object, in the constitutions of claims 1 to 7, the gasified composite fuel comprises methane and butane, and the light receiving means comprises methane. The light receiving means for detecting the concentration of methane receives light having a wavelength of 8.1 ± 0.1 μm, and the light receiving means for detecting butane concentration is 4.2. ± 0.1 μm, 6.3 ± 0.1 μm, 6.6 ± 0.5 μm, 6.9 ± 0.5 μm, 7.2 ± 0.5 μm, 10.5 ± 0.5 μm It is configured to receive light (the configuration of claim 10).
[0019]
Further, according to the present invention, in order to effectively achieve the above-mentioned main object, in the above-described first to tenth aspects, all of the component fuels of the gasification combined fuel are substantially equally absorbed. And a reference light receiving means for receiving a light having a wavelength and outputting a signal corresponding to the intensity of the received light, wherein the calculating means is configured to receive the reference light with respect to an output of the reference light receiving means when the concentration of fuel is zero. The apparatus is configured to correct a fuel concentration calculated based on signals output from the plurality of light receiving units based on a ratio of actual outputs of the units.
[0020]
Function and effect of the present invention
According to the configuration of the first aspect, a light source that irradiates a plurality of wavelengths of light, and a light corresponding to the intensity of the light of a specific wavelength that is received from the light emitted from the light source and passed through the gasified composite fuel is received. Since it has a plurality of light receiving means for outputting and a calculating means for calculating the concentration of the fuel based on signals outputted from the plurality of light receiving means, light of a plurality of wavelengths can be gasified at the same intensity by one light source. The fuel concentration can be passed through the fuel, so that the structure of the fuel concentration detecting device can be simplified as compared with the case where a plurality of light sources corresponding to each fuel component are used, and the gasification composite fuel is constituted. The concentration of the component fuel can be accurately detected.
[0021]
In addition, according to the configuration of the second aspect, since it includes the spectroscopic means for splitting the light radiated from the light source and passing through the gasified composite fuel to each light receiving means, before the light passes through the gasified composite fuel, Compared to the case of the structure that is split, the intensity of the light of a plurality of wavelengths when the light passes through the gasified composite fuel can be made to have the same intensity, thereby achieving the concentration of each component fuel. Can be detected with high accuracy.
[0022]
Further, according to the configuration of the third aspect, each light receiving unit includes a filter that allows light of a specific wavelength to pass therethrough, and a light-to-electric conversion element that converts the light passing through the filter into an electric signal corresponding to the intensity thereof. Therefore, each light receiving means can receive light having a wavelength that accurately corresponds to the light absorption characteristics of the component fuels constituting the gasified composite fuel, thereby enabling the concentration of each component fuel to be detected with high accuracy. it can.
[0023]
Further, according to the configuration of the fourth aspect, the gasified combined fuel is fuel flowing through the fuel passage, and the fuel passage is connected to the branch passage at the upstream end and the downstream end, and the fuel passage is connected to the fuel passage. Since the concentration detecting device is provided in the branch passage, light can be passed through the gasified composite fuel at a flow rate suitable for detecting the concentration of each component fuel with high accuracy, and the configuration of the fuel concentration detecting device It is possible to reduce the possibility that fuel adheres to the parts and the possibility that the concentration detection accuracy is reduced due to this.
[0024]
According to the fifth aspect of the present invention, the heating means for heating the gasified composite fuel to vaporize the liquid phase is provided in the branch passage upstream of the fuel concentration detecting device. It is possible to effectively reduce the risk that the liquid phase component of the fuel adheres to the components and the risk that the concentration detection accuracy is reduced due to the liquid component.
[0025]
According to the configuration of the sixth aspect, the light emitted from the light source passes through the gasified composite fuel flowing to the branch passage through the light transmitting window for irradiation, and is received by the light receiving means through the light transmitting window for light receiving. The light transmission window for irradiation and the light transmission window for light reception allow light to pass therethrough and suppress the flow of the gasified composite fuel from directly hitting the light transmission window for irradiation and the light transmission window for light reception. Since the cover is provided, the flow of the gasified composite fuel impinges on the light transmission window for direct irradiation and the light transmission window for light reception, and the fuel may adhere to those light transmission windows. Can be effectively reduced.
[0026]
According to the configuration of the seventh aspect, the light source and the light receiving means are disposed on one side of the branch passage, and the other side of the branch passage is gasified by light emitted from the light source and passed through the gasified composite fuel. A reflector that reflects light to the light receiving means via the composite fuel is provided, so that the optical path length required for concentration detection can be secured without increasing the cross-sectional area of the branch passage, and generally requires power and control. The light source and the light receiving means can be concentratedly arranged on one side of the branch passage.
[0027]
Further, according to the configuration of claim 8, the gasification composite fuel is composed of methane, propane, and butane, and the light receiving means is composed of light receiving means for detecting methane concentration, light receiving means for detecting propane concentration, and light receiving means for detecting butane concentration. The light receiving means for detecting methane concentration receives light having a wavelength of 8.1 ± 0.1 μm, and the light receiving means for detecting propane concentration detects 8.6 ± 0.1 μm, 9.5 ± 0.2 μm, and 11.1. Light of any wavelength of ± 0.2 μm is received, and the light receiving means for detecting butane concentration is any of 4.2 ± 0.1 μm, 6.3 ± 0.1 μm, and 10.5 ± 0.5 μm. , The concentration of methane, propane, and butane constituting the gasified composite fuel can be detected with high accuracy.
[0028]
Further, according to the configuration of the ninth aspect, the gasified composite fuel is composed of methane and propane, the light receiving means is composed of light receiving means for detecting methane concentration and light receiving means for detecting propane concentration, and the light receiving means for detecting methane concentration is Light having a wavelength of 8.1 ± 0.1 μm is received, and the light receiving means for detecting propane concentration is 6.6 ± 0.1 μm, 6.9 ± 0.5 μm, 7.2 ± 0.5 μm, 8.6 ±. Since it receives light with a wavelength of 0.1 μm, 9.5 ± 0.2 μm, or 11.1 ± 0.2 μm, it is necessary to detect the concentrations of methane and propane in the gasified composite fuel with high accuracy. Can be.
[0029]
Further, according to the configuration of claim 10, the gasified composite fuel is composed of methane and butane, the light receiving means is composed of light receiving means for detecting methane concentration and light receiving means for detecting butane concentration, and the light receiving means for detecting methane concentration is Light of 8.1 ± 0.1 μm wavelength is received, and light receiving means for detecting butane concentration is 4.2 ± 0.1 μm, 6.3 ± 0.1 μm, 6.6 ± 0.5 μm, 6.9 ±. Since it receives light with a wavelength of 0.5 μm, 7.2 ± 0.5 μm, or 10.5 ± 0.5 μm, it is necessary to detect the concentration of methane and butane in the gasified composite fuel with high accuracy Can be.
[0030]
According to the eleventh aspect of the present invention, a reference light receiving means for receiving light having a wavelength which is substantially equally absorbed by all the component fuels of the gasified composite fuel and outputting a signal corresponding to the intensity of the received light. Means is provided, based on the ratio of the actual output of the reference light receiving means to the output of the reference light receiving means when the concentration of fuel is 0, the fuel calculated based on the signals output from the plurality of light receiving means. Since the concentration is corrected, even if the fuel adheres to the components of the fuel concentration detecting device and the intensity of the light reaching the plurality of light receiving means is lower than the standard state, the concentration of each fuel component is detected with high accuracy. In addition, the frequency of maintenance of the fuel concentration detection device and the cost thereof can be reduced.
[0031]
Preferred embodiments of the means for solving the problems
According to a preferred aspect of the present invention, in the configuration of the first aspect, the fuel concentration detecting device is configured to have the same number of light receiving means as the number of component fuels constituting the gasified combined fuel ( Preferred embodiment 1).
[0032]
According to another preferred aspect of the present invention, in the configuration according to the first aspect, the calculating means includes an actual output of each light receiving means with respect to an output of each light receiving means when the concentration of each component fuel is zero. (Preferred mode 2).
[0033]
According to another preferred embodiment of the present invention, in the configuration of the fourth aspect, the branch passage is configured to extend above the fuel passage (preferred embodiment 3).
[0034]
According to another preferred embodiment of the present invention, in the configuration of the above-mentioned claim 4, the fuel concentration detecting device is configured to include a conduit defining a part of the branch passage (preferred embodiment 4).
[0035]
According to another preferred embodiment of the present invention, in the configuration of the above-mentioned claim 5, the heating means is configured to heat the gasified combined fuel to a substantially constant temperature (preferred embodiment 5).
[0036]
According to another preferred embodiment of the present invention, in the configuration of claim 6, the irradiation light transmitting window or the light receiving window is covered with a replaceable light transmitting cover plate. (Preferred embodiment 6).
[0037]
According to another preferred embodiment of the present invention, in the constitution of claim 11, the reference light-receiving means receives light having a wavelength substantially not absorbed by any component fuel of the gasification combined fuel. (Preferred mode 7).
[0038]
According to another preferred embodiment of the present invention, in the constitution of the above-mentioned claim 11, the gasification combined fuel comprises methane, propane and butane, and the reference light receiving means is 2.8 ± 0.1 μm; It is configured to receive light of any wavelength of 5.1 ± 0.3 μm (Preferred mode 8).
[0039]
According to another preferred embodiment of the present invention, in the configuration of the above-mentioned claim 11, the gasification combined fuel is composed of methane and propane, and the reference light receiving means is 2.8 ± 0.1 μm. It is configured to receive light having any wavelength of 1 ± 0.3 μm, 9.1 ± 0.1 μm, and 10.2 ± 0.2 μm (preferred embodiment 9).
[0040]
According to another preferred embodiment of the present invention, in the configuration of the above-mentioned claim 11, the gasification combined fuel comprises methane and butane, and the reference light-receiving means is 2.8 ± 0.1 μm; It is configured to receive light having any wavelength of 1 ± 0.3 μm, 9.3 ± 0.3 μm, and 11.5 ± 0.4 μm (preferred mode 10).
[0041]
According to another preferred aspect of the present invention, in the configuration according to the eleventh aspect, the calculating means includes an actual output of the reference light receiving means with respect to an output of the reference light receiving means when the fuel concentration is zero. Calculate the correction coefficient based on the ratio of each component fuel, calculate the ratio of the actual output of each light receiving means to the output of each light receiving means when the concentration of each component fuel is 0, and calculate the ratio of the output for each component fuel. It is configured so that the concentration of each component fuel is calculated based on the corrected output ratio after correction with a correction coefficient (preferred mode 11).
[0042]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings with reference to some preferred embodiments (hereinafter simply referred to as embodiments).
[0043]
First embodiment
FIG. 1 is a schematic configuration diagram showing a gas-liquid mixed fuel supply control device for an internal combustion engine incorporating a first embodiment of a fuel concentration detection device according to the present invention, and FIG. 2 shows the heat exchanger shown in FIG. FIG. 3 is an enlarged cross-sectional view, FIG. 3 is a schematic configuration diagram showing the fuel concentration detecting device of the first embodiment shown in FIG. 1, and FIG. 4 is a diagram showing the fuel concentration detecting device of the first embodiment shown in FIG. It is an expanded sectional view.
[0044]
In FIG. 1, reference numeral 10 denotes a fuel tank provided with a fuel introduction valve 10A. The fuel tank 10 stores a composite fuel 12 composed of methane, propane and butane in a liquid state at a high pressure of, for example, about 15 MPa. Have been. A liquid fuel take-out conduit 14 for taking out the composite fuel 12 in a liquid state extends into the fuel tank 10, and one end (tip) of the liquid fuel take-out conduit 14 is located at a lower part in the fuel tank 10, and the other end. Is connected to a regulator 18 via a fuel supply valve 16 which is an electromagnetic switching valve.
In the illustrated embodiment, the regulator 18 is integrally fixed to the fuel tank 10 together with the fuel supply valve 16.
[0045]
In the illustrated embodiment, a gas fuel extraction conduit 70 for extracting the gaseous composite fuel 12B extends in addition to the liquid fuel extraction conduit 14 in the fuel tank 10, and one end of the gas fuel extraction conduit 70. The (front end) is located in an upper part in the fuel tank 10, and the other end is connected to a regulator 74 via a fuel supply valve 72 which is an electromagnetic on-off valve. As shown, the regulator 74 is also integrally fixed to the fuel tank 10 together with the fuel supply valve 72.
[0046]
The regulator 18 reduces the pressure of the liquid fuel 12 taken out of the fuel tank 10 to a predetermined pressure and supplies it to one end of a fuel supply conduit 20, and the other end of the fuel supply conduit 20 changes the state of the liquid composite fuel into a gaseous state. Connected to the heat exchanger 22 to be heated. One end of a fuel supply conduit 24 for supplying a composite fuel in a gaseous state is connected to the heat exchanger 22, and the other end of the fuel supply conduit 24 is connected to a fuel delivery device 26. It is connected to an injection device 28. Similarly, the regulator 74 reduces the pressure of the gaseous fuel 12B taken out of the fuel tank 10 to a predetermined pressure and supplies it to one end of a fuel supply conduit 76. The other end of the fuel supply conduit 76 is connected to the heat exchanger 22. I have. A regulator may be provided downstream of the heat exchanger 22 so that the fuel pressure of the gaseous fuel can be adjusted.
[0047]
As is well known, the fuel injection device 28 is provided in the intake pipe 32 of each cylinder of the internal combustion engine 30 so as to inject and supply gaseous composite fuel into the intake pipe 32. The internal combustion engine 30 in the illustrated embodiment is a water-cooled internal combustion engine, and exhaust gas generated by burning fuel in a combustion chamber 34 of the internal combustion engine 30 passes through an exhaust pipe 36 and a muffler (not shown). The exhaust gas is released into the atmosphere, and an exhaust gas purification catalyst 38 is provided in the exhaust pipe 36.
[0048]
As shown in FIG. 2, the heat exchanger 22 has a housing 40 to which fuel supply conduits 20, 24, 76 are connected, and an internal space 40A of the housing 40 connects the fuel supply conduits 20, 24, 76 to each other. Communication is established. In particular, in the illustrated embodiment, a fuel supply conduit 20 for supplying the composite fuel 12 in a liquid state is connected to a lower end of the housing 40 and supplies the composite fuel 12A changed to a gaseous state in an internal space 40A. The fuel supply conduit 24 is connected to the upper end of the housing 40. Therefore, the outlet for discharging the gaseous composite fuel 12A from the heat exchanger 22 is positioned higher than the inlet for introducing the liquid composite fuel 12 to the heat exchanger 22. The fuel supply conduit 76 is connected to the upper portion of the heat exchanger 22 and is always in communication with the fuel supply conduit 24 that supplies the composite fuel in a gaseous state.
[0049]
A cooling water conduit 42 extends into the internal space 40A of the housing 40, and the cooling water conduit 42 in the internal space 40A is provided with a plurality of fins 44. Cooling water 46A whose temperature has been raised from the cooling water circulation system 46 of the internal combustion engine 30 is circulated and supplied to the cooling water conduit 42, whereby the heat exchanger 22 is connected to the high-temperature cooling water flowing through the cooling water conduit 42 and the internal space 40A. The heat exchange is performed between the composite fuel and the composite fuel, and the heat of the cooling water is used to change the state of the composite fuel in a liquid state to a gas state.
[0050]
Although not shown in the drawing, the composite fuel in the liquid state is changed so that the composite fuel in the liquid state is surely changed to the gas state and the composite fuel in the liquid state is not supplied to the fuel injection device 28. The heat exchanger 22 may be provided with, for example, a float on-off valve that shuts off communication between the fuel supply conduit 20 and the internal space 40A when the fuel level 12D becomes higher than a predetermined amount.
[0051]
As shown in FIG. 1, the fuel supply conduit 24 is provided with a fuel concentration detecting device 48 for detecting the concentration of the component fuel in the gaseous composite fuel flowing through the conduit by using an infrared absorption method. A signal indicating the fuel concentration detected by the fuel concentration detecting device 48 is input to the electronic control device 50. Although not shown in detail in the figure, the electronic control device 50 has, for example, a CPU, a ROM, a RAM, and an input / output port device, which are connected to each other by a bidirectional common bus. Includes microcomputer.
[0052]
The fuel delivery device 26 is provided with a fuel temperature sensor 52 and a fuel pressure sensor 54, and signals indicating the fuel temperature Tf and the fuel pressure Pf detected by these sensors are input to the electronic control unit 50. An air-fuel ratio detection sensor 56 is provided in the exhaust pipe 36 upstream of the exhaust gas purification catalyst 38 when viewed from the flow of exhaust gas, and the exhaust pipe 36 downstream of the exhaust gas purification catalyst 38 is₂Sensors 58 are provided, and signals indicating the actual air-fuel ratio Ra and the oxygen concentration Do detected by these sensors are also input to the electronic control unit 50.
[0053]
A signal indicating the cooling water temperature Tc is input to the electronic control unit 50 from a cooling water temperature sensor 60 provided in the cooling water circulation system 46. The throttle opening sensor 62, the engine speed sensor 64, the air flow meter 66, the crank angle sensor 68 Thus, signals indicating the throttle opening θ, the engine speed Ne, the intake air amount Fa, and the crank angle φ are input.
[0054]
As shown in FIG. 3, an upstream end and a downstream end of a branch conduit 80 as a branch passage are connected to the fuel supply conduit 24 as a fuel passage. 80. In the illustrated embodiment, branch conduit 80 extends above fuel supply conduit 24. As shown in FIGS. 3 and 4, the fuel concentration detecting device 48 includes a conduit 82 connected at both ends to a branch conduit 80 and defining a part of the branch passage.
[0055]
As shown in detail in FIG. 4, the fuel concentration detecting device 48 includes one light emitting member 88 as a light source for irradiating light 86 of a plurality of wavelengths, three photodiodes 90 to 94 as light receiving elements, A reflecting mirror 96 for reflecting light radiated from the member 88 and passing through the gasified composite fuel flowing through the conduit 82, and directs the light reflected by the reflecting mirror 96 and passed through the gasified composite fuel to three photodiodes 90 to 94. And a spectroscope 98 for splitting light.
[0056]
The light emitting member 88 and the photodiodes 90 to 94 are fixed to a substrate 100 spaced above the conduit 82, and are housed in the housing 104 together with the substrate 100 and the substrate 102 fixed to the conduit 82. The reflecting mirror 96 is fixed to the conduit 82 on the side opposite to the light emitting member 88 and the photodiodes 90 to 94 with respect to the center of the flow path of the conduit 82.
[0057]
In the illustrated embodiment, the light-emitting member 88 includes an infrared-emitting illuminant, and the light 86 emitted by the light-emitting member 88 passes through the glass plate 106 and enters the conduit 82, and is transmitted to the reflecting mirror 96. Incident. The light reflected by the reflecting mirror 96 enters the spectroscope 98 after passing through the glass plate 108, and the light split by the spectroscope 98 passes through the optical filters 110 to 114, and the corresponding photodiodes 90 to 94 respectively. Incident on.
[0058]
Thus, the glass plate 106 cooperates with the hole provided in the conduit 82 to define the light transmitting window, and the glass plate 108 cooperates with the hole provided in the conduit 82 to define the light transmitting window for light reception. I have decided. The glass plates 106 and 108 are made of a material having a high infrared transmittance such as synthetic sapphire, silicon, and zinc / selenium, and are fixed to the substrate 102, respectively. Sealed by seal 110A.
[0059]
The photodiodes 90 to 94 have the same characteristics as each other, and output an electric signal of a voltage corresponding to the intensity of incident light. Reflecting mirror 96 A metal plate or a ceramic plate having a low coefficient of thermal expansion is plated with chromium, gold, platinum or the like or mirror-polished to increase the light reflectance. The spectroscope 98 is, for example, a combination of three convex lenses, and is fixed to a glass plate 108. The optical filters 110 to 114 are so-called interference filters in which a high-refractive-index layer and a low-refractive-index layer of light are vacuum-deposited on the surface of a glass plate so as to have a thickness of 1/4 of the wavelength, and together with the photodiodes 90 to 94 It is fixed to the substrate 100. The material to be deposited is selected according to the wavelength of light to be transmitted by the optical filters 110 to 114.
[0060]
For example, FIG. 6 shows the relationship between the wavelength of infrared rays and the absorptivity of methane, propane, butane, and water vapor. As can be seen from FIG. 6, the wavelength at which the infrared absorption specific to each component is high, that is, the infrared absorption of the component fuel whose concentration is to be detected is high but the infrared absorption of the other component fuel is low, is adopted. It can be understood that the concentration of each component fuel can be detected while suppressing the influence of other component fuels. In the illustrated embodiment, the transmission wavelength of the methane concentration detection optical filter 110 is set to 8.1 ± 0.1 μm, and the transmission wavelength of the propane concentration detection optical filter 112 is 8.6 ± 0. 1 μm, 9.5 ± 0.2 μm, 11.1 ± 0.2 μm, and the transmission wavelength of the optical filter 114 for detecting butane concentration is 4.2 ± 0.1 μm, 6.3 ± 0. It is set to 1 μm or 10.5 ± 0.5 μm.
[0061]
Covers 116 and 118 are fixed to the lower surface of the substrate 102 corresponding to the glass plates 106 and 108, respectively. The covers 116 and 118 cover the glass plates 106 and 108 so that the gasified combined fuel flowing in the conduit 82 does not directly hit the glass plates 106 and 108, and have holes that allow the passage of light 86. Similarly, a cover 120 is fixed to the inner surface of the conduit 82. The cover 120 has a hole that covers the reflector 96 and allows light 86 to pass therethrough so that the gasified composite fuel flowing in the conduit 82 does not directly hit the reflector 96. A PTC heater 122 for heating the gasified composite fuel flowing in the conduit 82 to a constant temperature of, for example, 30 ° C. is fixed to the inner surface of the conduit 82 on the upstream side of the covers 118 and 120.
[0062]
The supply and control of electric power to the light emitting member 88 are performed by an electric circuit 124 fixed to the upper surface of the substrate 100, and the supply and control of electric power to the photodiodes 90 to 94 are performed by an electric circuit 126 fixed to the upper surface of the substrate 100. The supply and control of power to the PTC heater 122 are performed by an electric circuit 128 fixed on the upper surface of the substrate 102. The electric circuit 126 calculates the concentrations Cm, Cp, and Cb of methane, propane, and butane, which are the component fuels of the gasification combined fuel, based on the outputs from the photodiodes 90 to 94, and outputs signals indicating the concentrations to the electronic control unit 50. Output to
[0063]
For example, if the fuel concentration is 0 [mol / m³], The fuel concentration with respect to the output voltage Io of the photodiodes 90 to 94 is C [mol / m 2].³], The ratio It / Io of the output voltages It of the photodiodes 90 to 94 is determined by the device wavelength determined by the light emitting member 88, the optical filters 110 to 114, and the like, and by the wavelength of light, the temperature and the pressure of the fuel. When the molar absorption coefficient is ε and the optical path length is L, it is represented by the following equation 1.
[0064]
It / Io = A · exp (−ε · CL) Ｃ (1)
FIG. 5 shows the relationship between the output voltage ratio It / Io, the methane concentration Cm, and the stoichiometric air-fuel ratio A / F for methane. The electric circuit 126 stores the maps of FIG. 5 and a similar relationship with respect to methane, propane, and butane, calculates the ratio It / Io of the output voltage, and calculates the concentrations Cm of methane, propane, and butane from each map. , Cp, Cb.
[0065]
When an ignition switch (not shown) is closed, the electronic control unit 50 determines whether the cooling water temperature Tc detected by the cooling water temperature sensor 60 is equal to or lower than a reference value Tco (constant), When the cooling water temperature Tc exceeds the reference value Tco, the fuel supply valve 16 is opened and the fuel supply valve 72 is maintained in the closed state, so that the liquid fuel mixture 12 is transferred from the fuel tank 10 to the heat exchanger 22. Supply.
[0066]
On the other hand, in a situation where the cooling water temperature Tc is equal to or higher than the reference value Tco, and it is difficult for the heat exchanger 22 to properly change the liquid state of the mixed fuel into the gaseous state, the electronic control unit 50 supplies the fuel. By maintaining the valve 16 in the closed state and opening the fuel supply valve 72, the gaseous mixed fuel 12 </ b> B is supplied from the fuel tank 10 to the heat exchanger 22.
[0067]
Even when the internal combustion engine 30 is operated for several minutes even at a low temperature, the cooling water temperature Tc rises and exceeds the reference value Tco. At this stage, the fuel supply valve 16 is opened and the fuel supply valve 72 is closed. As a result, the mixed fuel 12 in a liquid state is supplied from the fuel tank 10 to the heat exchanger 22, and the fuel changed to a gaseous state by the heat exchanger 22 is supplied to the internal combustion engine 30.
[0068]
Further, the electronic control unit 50 calculates the H / C ratio of the composite fuel based on the concentrations Cm, Cp, and Cb of the component fuel detected by the fuel concentration detecting device 48, and theoretically calculates the target air-fuel ratio based on the H / C ratio. The air-fuel ratio Rt is calculated, and the fuel injection period correction coefficient Ka is calculated based on the stoichiometric air-fuel ratio Rt. For example, the first target is calculated based on the basic fuel injection period Tb and the fuel injection period correction coefficient Ka when methane is 100%. The fuel injection period T1 is calculated.
[0069]
The electronic control unit 50 also controls the actual air-fuel ratios Ra and O detected by the air-fuel ratio detection sensor 56.₂The corrected actual air-fuel ratio Raa is calculated based on the oxygen concentration Do detected by the sensor 58 in a manner known in the art, and based on the deviation between the corrected actual air-fuel ratio Raa and the stoichiometric air-fuel ratio Rt. A second target fuel injection period T2 for reducing the deviation is calculated, a final target fuel injection period Tt is calculated based on the target fuel injection periods T1 and T2, and a crank angle φ detected by the crank angle sensor 68 is calculated. Based on the predetermined injection timing and the final target fuel injection period Tt, the fuel injection amount of each fuel injection device 28 is controlled.
[0070]
The control of fuel supply to the internal combustion engine 30 performed by the electronic control unit 50 based on the component fuel concentrations Cm, Cp, and Cb detected by the fuel concentration detection device 48 does not constitute the gist of the present invention. May be performed in any known manner.
[0071]
Next, a routine for calculating the concentration of the component fuel executed by the electric circuit 126 in the first embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 7 is started by closing an ignition switch (not shown), and is repeatedly executed at predetermined time intervals.
[0072]
First, in step 100, the output voltage Itm of the photodiode 90 for detecting methane concentration is read, and in step 150, the output voltage ratio Itm / Io is calculated based on the output voltage Itm. Then, the methane concentration Cm is calculated from the methane concentration calculation map corresponding to FIG. 5 based on the output voltage ratio Itm / Io, and a signal indicating the concentration Cm is output to the electronic control unit 50.
[0073]
At step 250, the output voltage Itp of the propane concentration detecting photodiode 92 is read. At step 300, the output voltage ratio Itp / Io is calculated based on the output voltage Itp. At step 350, The propane concentration Cp is calculated from the propane concentration calculation map corresponding to FIG. 5 based on the output voltage ratio Itp / Io, and a signal indicating the concentration Cp is output to the electronic control unit 50.
[0074]
In step 400, the output voltage Itb of the photodiode 94 for detecting butane concentration is read. In step 450, the output voltage ratio Itb / Io is calculated based on the output voltage Itb. In step 500, The butane concentration Cb is calculated from the butane concentration calculation map corresponding to FIG. 5 based on the output voltage ratio Itb / Io, and a signal indicating the concentration Cb is output to the electronic control unit 50.
[0075]
Thus, according to the illustrated first embodiment, the transmission wavelengths of the optical filters 110 to 114 are set to wavelengths at which the infrared absorptivity specific to each fuel component is high. The output voltages Itm, Itp, Itb of the photodiodes 90 to 94 corresponding to are output, and the output voltage ratios Itm / Io, Itp / Io, Itb / Io are calculated in steps 150, 300, 450, respectively. Since the methane concentration Cm, the propane concentration Cp, and the butane concentration Cb are calculated based on the output voltage ratios at 200, 350, and 500, the concentrations of methane, propane, and butane can be detected with high accuracy. Can be.
[0076]
In particular, according to the illustrated embodiment, the concentrations of methane, propane, and butane, which are the fuel components constituting the gasification combined fuel, are individually calculated. For example, as in the second embodiment described below, As compared with the case where the concentration ratio is calculated, the control of the composite fuel supply amount to the internal combustion engine can be performed easily and accurately.
[0077]
Second embodiment
In this embodiment, the electric circuit 126 calculates the concentrations Cm, Cp, and Cb of methane, propane, and butane based on the ratio of each output voltage, as in the case of the first embodiment, and calculates the methane concentration. And the ratio Cp / Cb of the concentration of butane to the concentration of methane is calculated, and a signal indicating these ratios is output to the electronic control unit 50. The fuel injection period of the fuel injection device 28 is controlled based on / Cm and Cp / Cb.
[0078]
FIG. 8 shows a concentration ratio calculation control routine achieved by the electric circuit 126 in this embodiment. In steps 200, 350, and 500, the methane concentration Cm, the propane concentration Cp, and the butane concentration Cb, respectively. Steps 100 to 500 are executed in the same manner as in the above-described first embodiment, except that a signal indicating is not output to the electronic control device 50.
[0079]
In step 550 executed after step 500, the ratio Cp / Cm of the concentration of propane to the concentration of methane and the ratio Cp / Cb of the concentration of butane to the concentration of methane are calculated, and these ratios are calculated. The indicated signal is output to the electronic control unit 50.
[0080]
Thus, according to the illustrated second embodiment, the ratio Cp / Cm of the concentration of propane to the concentration of methane and the ratio Cp / Cb of the concentration of butane to the concentration of methane are calculated. Even if the intensity of light passing through the gasified composite fuel flowing through the conduit 82 and reaching the photodiodes 90 to 94 is reduced due to the attachment of the fuel component to the surfaces of the gasified composite fuel 106 and 108, The concentration ratio of the component fuel can be accurately detected.
[0081]
Third embodiment
In this embodiment, as shown in FIG. 9, a reference photodiode 130 is provided in addition to the photodiodes 90 to 94, and the spectroscope 98 'is reflected by the reflecting mirror 96 to form a gasification composite. The light passing through the fuel is split into four photodiodes 90 to 94 and 130. An optical filter 132 similar to the optical filters 110 to 114 is provided at a position corresponding to the photodiode 130. The transmission wavelength of the reference optical filter 132 is such that infrared light is hardly absorbed by any of methane, propane, and butane. The wavelength is set to either 2.8 ± 0.1 μm or 5.1 ± 0.3 μm.
[0082]
FIG. 11 shows a concentration ratio calculation control routine achieved by the electric circuit 126 in this embodiment. In step 10, the output voltage Ito of the reference photodiode 130 is read, and step 20 is executed. In step 30, the ratio Ito / Io of the reference output voltage is calculated based on the output voltage Ito. In step 30, the ratio becomes smaller as the ratio is smaller than 1 based on the ratio Ito / Io of the reference output voltage. The correction coefficient Ka is calculated from the map shown in FIG.
[0083]
In this embodiment, the output voltage ratio Itm ′ / Io is calculated as Ka · Itm / Io based on the output voltage Itm and the correction coefficient Ka in step 160, and the output voltage ratio is calculated in step 210. The methane concentration Cm is calculated from the methane concentration calculation map corresponding to FIG. 5 based on Itm '/ Io, and a signal indicating the concentration Cm is output to the electronic control unit 50.
[0084]
Similarly, in step 310, the output voltage ratio Itp '/ Io is calculated as Ka · Itp / Io based on the output voltage Itp and the correction coefficient Ka, and in step 360, based on the output voltage ratio Itp' / Io. The propane concentration Cp is calculated from the propane concentration calculation map corresponding to FIG. 5, and a signal indicating the concentration Cp is output to the electronic control unit 50. In step 460, the output voltage Itb and the correction coefficient Ka are used to calculate the output voltage Itb. The ratio Itb '/ Io is calculated as Ka.Itb / Io. In step 510, the butane concentration Cb is calculated from the butane concentration calculation map corresponding to FIG. 5 based on the output voltage ratio Itb' / Io. A signal indicating Cb is output to electronic control device 50.
[0085]
Thus, according to the third embodiment shown in the figure, in step 20, the ratio Ito / Io of the reference output voltage is calculated for the wavelength at which infrared light is hardly absorbed by any of methane, propane and butane. Then, based on the ratio Ito / Io of the reference output voltage, a correction coefficient Ka is calculated so as to be larger as this ratio is smaller than 1, and the output voltages corrected by the correction coefficient Ka in steps 160, 310 and 460, respectively. The ratios Itm '/ Io, Itp' / Io, Itb '/ Io are calculated in steps 210, 360, and 510 based on the ratios of the output voltages, respectively, based on the methane concentration Cm, propane concentration Cp, and butane concentration. Cb is calculated.
[0086]
In this case, the ratio Ito / Io of the reference output voltage is substantially 1 when no fuel component is attached to the surfaces of the reflecting mirror 96 and the glass plates 106 and 108, for example. In the situation where the fuel component adheres to the surfaces of the glass plates 106 and 108 and the intensity of the light passing through the gasified composite fuel flowing through the conduit 82 and reaching the photodiodes 90 to 94 decreases, the intensity becomes 1 And the smaller the degree of decrease in light intensity, the smaller the value.
[0087]
According to the third embodiment shown in the figure, the correction coefficient Ka is calculated so as to increase as the ratio Ito / Io of the reference output voltage decreases, and the output voltage ratio Itm '/ Io corrected by the correction coefficient Ka, Since the concentration of each component fuel is calculated based on Itp '/ Io and Itb' / Io, the fuel flows through the conduit 82 due to, for example, fuel components adhering to the surfaces of the reflecting mirror 96 and the glass plates 106 and 108. Even in a situation where the intensity of light passing through the gasified composite fuel and reaching the photodiodes 90 to 94 decreases, the concentrations of methane, propane, and butane can be detected with high accuracy. Maintenance frequency and cost can be greatly reduced.
[0088]
In particular, according to each of the illustrated embodiments, since the number of the light emitting members 88 as the light source is one, the structure of the fuel concentration detecting device 48 can be simplified and the cost can be reduced as compared with the case where a plurality of light sources are used. The output of the light emitting member 88 can be easily adjusted. Further, the light 86 emitted from the light emitting member 88 passes through the gasified composite fuel flowing in the conduit 82 and is then separated by the spectroscope 98 toward the photodiodes 90 to 94, so that the optical path length for each fuel component is reliably determined. The same can be set, and the concentration of the fuel component can be detected more accurately than in the case where the spectrometer 98 is not used.
[0089]
According to each of the above-described embodiments, the upstream end and the downstream end of the branch conduit 80 as a branch passage are connected to the fuel supply conduit 24, and the fuel concentration detection device 48 is provided in the branch conduit 80. Therefore, the flow rate of the gasified composite fuel flowing to the branch conduit 80 can be reduced irrespective of the flow rate of the gasified composite fuel flowing to the fuel supply conduit 24, and the fuel concentration detection device 48 controls a part of the branch conduit 80. Since the fuel concentration detecting device 48 can be attached to the branch conduit 80 by connecting the conduit 82 to the branch conduit 80, the fuel concentration detecting device 48 can be easily and efficiently attached. It can be carried out.
[0090]
Further, according to the above-described embodiments, covers 116 and 118 are provided to cover the glass plates 106 and 108 so that the gasified composite fuel flowing in the conduit 82 does not directly hit the glass plates 106 and 108, and the conduit 82 Since the cover 120 that covers the reflecting mirror 96 is provided so that the gasified composite fuel flowing inside does not directly hit the reflecting mirror 96, the fuel may adhere to the surfaces of the reflecting mirror 96 and the glass plates 106 and 108. , And the possibility that the concentration detection accuracy is reduced due to the adhesion of the fuel can be effectively reduced.
[0091]
According to the above-described embodiments, the PTC heater 122 for heating the gasified composite fuel flowing in the conduit 82 to a constant temperature of, for example, 30 ° C. is provided on the inner surface of the conduit 82 upstream of the covers 118 and 120. Therefore, it is possible to effectively reduce the possibility that the concentration detection accuracy is reduced due to the fluctuation of the temperature of the gasified composite fuel due to the influence of the outside air temperature or the like.
[0092]
Further, according to each of the above-described embodiments, the light 86 emitted by the light emitting member 88 passes through the conduit 82 and is reflected by the reflecting mirror 96, and the reflected light passes through the conduit 82 to the spectroscope 98. Since the light enters and is separated, and the separated light enters the corresponding photodiodes 90 to 94 via the optical filters 110 to 114, the flow path cross-sectional area of the conduit 82 is reduced as compared with a case where a reflecting mirror is not used. And the light emitting members 88, the photodiodes 90-94, and the electrical circuits 124, 126 controlling them can be located on the same side of the conduit 82, thereby making the fuel concentration detection device 48 compact. And maintenance can be easily performed.
[0093]
In the above, the present invention has been described in detail with respect to a specific embodiment, but the present invention is not limited to the above embodiment, and various other embodiments are possible within the scope of the present invention. Some will be apparent to those skilled in the art.
[0094]
For example, in each of the above embodiments, the composite fuel 12 is composed of methane, propane, and butane, but the composite fuel may be a combination of other fuels.
In particular, in the above first or second embodiment, when the composite fuel is composed of methane and propane, the transmission wavelength of the optical filter 110 for detecting methane concentration is set to 8.1 ± 0.1 μm. , The transmission wavelength of the optical filter 112 for detecting the concentration of propane is 6.6 ± 0.1 μm, 6.9 ± 0.5 μm, 7.2 ± 0.5 μm, 8.6 ± 0.1 μm, 9.5 ± 0. It is preferable to set the wavelength to any one of 0.2 μm and 11.1 ± 0.2 μm. When the composite fuel is composed of methane and butane, the transmission wavelength of the optical filter 110 for detecting methane concentration is 8 μm. The transmission wavelength of the optical filter 114 for detecting butane concentration is 4.2 ± 0.1 μm, 6.3 ± 0.1 μm, 6.6 ± 0.5 μm, 6.9 ±. Any wave of 0.5μm, 7.2 ± 0.5μm, 10.5 ± 0.5μm It is preferably set to.
[0095]
In the third embodiment, when the composite fuel is composed of methane and propane, the transmission wavelength of the reference optical filter 132 is 2.8 ± 0.1 μm, 5.1 ± 0.3 μm, It is preferably set to 9.1 ± 0.1 μm or 10.2 ± 0.2 μm. When the composite fuel is composed of methane and butane, the transmission wavelength of the reference optical filter 132 is 2 It is preferably set to any one of 0.8 ± 0.1 μm, 5.1 ± 0.3 μm, 9.3 ± 0.3 μm, and 11.5 ± 0.4 μm.
[0096]
In each of the above-described embodiments, the light 86 emitted from the light emitting member 88 passes through the gasified composite fuel flowing through the conduit 82, and is then split by the spectroscope 98 toward the photodiodes 90 to 94. However, the spectrometer 98 may be omitted, and the intensity of light passing through the gasified composite fuel may be modified so as to be detected by the photodiodes 90 to 94.
[0097]
Further, in each of the above embodiments, the fuel concentration detecting device 48 is provided in the branch conduit 80, but the branch conduit 80 may be omitted, and the fuel concentration detecting device 48 may be provided in the fuel supply conduit 24. Also, a heating means such as the PTC heater 122 may be omitted.
[0098]
In the above-described embodiments, the covers 116 and 118 that cover the glass plates 106 and 108 are provided, and the cover 120 that covers the reflecting mirror 96 is provided. However, these covers may be omitted. In addition, a light-transmissive cover plate that covers the reflecting mirror 96 and the glass plates 106 and 108 so that fuel does not adhere thereto is detachably attached, and the cover plate is replaced when the fuel adheres to the surface of the cover plate. May be modified so that the light transmittance can be easily restored.
[0099]
In each of the above embodiments, the light 86 emitted from the light emitting member 88 passes through the conduit 82 and is reflected by the reflecting mirror 96. However, the reflecting mirror is omitted, and the light emitting member is omitted. 88 and photodiodes 90-94 may be located on either side of the passage through which the gasified combined fuel passes.
[0100]
In each of the above embodiments, the gasified composite fuel is the fuel of the internal combustion engine, but the fuel concentration detecting device 48 is applied to the gasified composite fuel composed of a plurality of hydrocarbon fuels other than the fuel of the internal combustion engine. May be done.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a gas-liquid mixed fuel supply control device for an internal combustion engine in which a first embodiment of a fuel concentration detection device according to the present invention is incorporated.
FIG. 2 is an enlarged sectional view showing the heat exchanger shown in FIG.
FIG. 3 is a schematic configuration diagram showing the fuel concentration detection device of the first embodiment shown in FIG.
FIG. 4 is an enlarged sectional view showing the fuel concentration detection device of the first embodiment shown in FIG.
FIG. 5 is a graph showing the relationship between the output voltage ratio It / Io of methane, the methane concentration Cm, and the stoichiometric air-fuel ratio A / F.
FIG. 6 is a graph showing the relationship between infrared wavelength and infrared absorptance for methane, propane, butane, and water vapor.
FIG. 7 is a flowchart illustrating a fuel concentration detection control routine according to the first embodiment.
FIG. 8 is a flowchart illustrating a fuel concentration detection control routine according to the second embodiment.
FIG. 9 is an enlarged sectional view showing a third embodiment of the fuel concentration detection device according to the present invention.
FIG. 10 is a graph showing a relationship between a reference output voltage ratio Ito / Io and a correction coefficient Ka.
FIG. 11 is a flowchart illustrating a fuel concentration detection control routine according to a third embodiment.
FIG. 12 shows a relationship between a change in pressure in the fuel tank and a stoichiometric ratio of butane in the fuel and a stoichiometric air-fuel ratio when a mixed fuel of 70% methane and 30% butane is taken out of the fuel tank in a liquid state. It is a graph.
[Explanation of symbols]
10. Fuel tank
12 ... Gas-liquid mixed fuel
18, 74… Regulator
22 ... Heat exchanger
28 ... Fuel injection device
30 internal combustion engine
48 ... Fuel concentration detector
50 Electronic control unit
80 ... Branch conduit
88 ... Light emitting member
90-94 ... photodiode
96 ... Reflector
98 ... Spectroscope
110-114 ... Optical filter
116-120 ... Cover
122 ... PTC heater
130 ... photodiode for reference
132 Reference optical filter

Claims (11)

In a fuel concentration detection device for a gasified composite fuel composed of a plurality of hydrocarbon fuels, a light source for irradiating light of a plurality of wavelengths, and light received from the light source and passed through the gasified composite fuel is received and received. A gasification composite comprising: a plurality of light receiving means for outputting a signal corresponding to the intensity of light having a specific wavelength; and a calculating means for calculating a fuel concentration based on signals output from the plurality of light receiving means. A fuel concentration detector for fuel. 2. The gas concentration composite fuel concentration detecting device according to claim 1, further comprising a spectroscopic means for splitting light emitted from the light source and passing through the gasified composite fuel to each light receiving means. Each light receiving means includes a filter for passing light of a specific wavelength, and a light-to-electric conversion element for converting the light passing through the filter to an electric signal of a voltage corresponding to the intensity of the light. The fuel concentration detecting device for a gasified composite fuel according to claim 1 or 2. The gasified combined fuel is fuel flowing through a fuel passage, and a branch passage is connected to the fuel passage at upstream and downstream ends. The fuel concentration detection device is provided in the branch passage. The fuel concentration detecting device for a gasified composite fuel according to any one of claims 1 to 3, wherein: 5. The gasification composite fuel according to claim 4, wherein a heating means for heating the gasification composite fuel to vaporize a liquid phase is provided in the branch passage upstream of the fuel concentration detection device. Fuel concentration detector. The light emitted from the light source passes through the gasified composite fuel flowing through the branch passage through the light transmission window for irradiation, and is received by the light receiving means through the light transmission window for light reception. A cover is provided on the light transmitting window and the light transmitting window for light reception to allow light to pass therethrough and suppress the flow of gasified composite fuel from directly hitting the light transmitting window for irradiation and the light transmitting window for light receiving. The fuel concentration detecting device for a gasified composite fuel according to claim 1, wherein: The light source and the light receiving means are arranged on one side of the branch passage, and the other side of the branch passage receives the light irradiated from the light source and passed through the gasified composite fuel through the gasified composite fuel. 7. The fuel concentration detecting device according to claim 4, wherein a reflecting mirror for reflecting the light from the means is provided. The gasified composite fuel is composed of methane, propane, and butane, and the light-receiving means is composed of light-receiving means for detecting methane concentration, light-receiving means for detecting propane concentration, and light-receiving means for detecting butane concentration. Receives light having a wavelength of 8.1 ± 0.1 μm, and the light-receiving means for detecting propane concentration is 8.6 ± 0.1 μm, 9.5 ± 0.2 μm, or 11.1 ± 0.2 μm. And the butane concentration detecting light-receiving means receives light having any wavelength of 4.2 ± 0.1 μm, 6.3 ± 0.1 μm, and 10.5 ± 0.5 μm. The fuel concentration detecting device for a gasified composite fuel according to claim 1, wherein: The gasified composite fuel comprises methane and propane, the light receiving means comprises light receiving means for detecting methane concentration and light receiving means for detecting propane concentration, and the light receiving means for detecting methane concentration has a density of 8.1 ± 0.1 μm. Wavelength light, and the propane concentration detecting light receiving means is 6.6 ± 0.1 μm, 6.9 ± 0.5 μm, 7.2 ± 0.5 μm, 8.6 ± 0.1 μm, 9.5. The fuel concentration detecting device for a gasified composite fuel according to any one of claims 1 to 7, wherein light having a wavelength of any of ± 0.2 µm and 11.1 ± 0.2 µm is received. The gasified composite fuel is composed of methane and butane, the light receiving means is composed of light receiving means for detecting methane concentration and light receiving means for detecting butane concentration, and the light receiving means for detecting methane concentration is 8.1 ± 0.1 μm. The light receiving means for detecting the butane concentration is 4.2 ± 0.1 μm, 6.3 ± 0.1 μm, 6.6 ± 0.5 μm, 6.9 ± 0.5 μm, 7.2. The fuel concentration detecting device for a gasified composite fuel according to any one of claims 1 to 7, wherein light having a wavelength of any of ± 0.5 µm and 10.5 ± 0.5 µm is received. Reference light receiving means for receiving light having a wavelength substantially equivalently absorbed by all the component fuels of the gasified composite fuel and outputting a signal corresponding to the intensity of the received light, and the calculating means includes a fuel concentration Correcting the fuel concentration calculated based on the signals output from the plurality of light receiving means based on the ratio of the actual output of the reference light receiving means to the output of the reference light receiving means when is zero. The fuel concentration detecting device for a gasified composite fuel according to claim 1, wherein:

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