JP2009299625A - Fuel type estimation device for internal combustion engine and control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily estimate a mixing ratio of first liquid fuel and second liquid fuel in an internal combustion engine using mixed liquid fuel mixed with the first liquid fuel and the second liquid fuel. <P>SOLUTION: An upstream side intake air temperature sensor 42 detects an intake air temperature Tiu at an upstream side of an injector 22. A downstream side intake air temperature sensor 44 detects an intake air temperature Tid at a downstream side of the injector 22. A mixing ratio estimation part 52 estimates a mixing ratio of gasoline and alcohol fuel in the mixed liquid fuel based on the intake air temperature Tiu detected by the upstream side intake air temperature sensor 42 and the intake air temperature Tid detected by the downstream side intake air temperature sensor 44. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel type estimation device for an internal combustion engine and a control device for the internal combustion engine, and in particular, in an internal combustion engine that uses a mixed liquid fuel obtained by mixing a first liquid fuel and a second liquid fuel having different latent heats of evaporation. The present invention relates to a fuel type estimation device for an internal combustion engine that estimates a mixing ratio of a liquid fuel and a second liquid fuel, and a control device for an internal combustion engine including the same.

  In recent years, in an internal combustion engine, it has been proposed to use a mixed liquid fuel obtained by mixing a hydrocarbon-based fuel such as gasoline with other types of fuel such as alcohols. When such a mixed liquid fuel is used, the mixing ratio of each fuel component in the mixed liquid fuel is not always constant, and a mixed liquid fuel different from the assumed mixing ratio may be used. It is done. For example, when using a mixed liquid fuel of gasoline and alcohol, if the mixing ratio of alcohol in the mixed liquid fuel is lower than the expected mixing ratio, knocking occurs due to the lower octane number of the entire mixed liquid fuel. It becomes easy to do. In addition, when the mixing ratio of the alcohols in the mixed liquid fuel changes from the assumed mixing ratio, the stoichiometric air-fuel ratio of the entire mixed liquid fuel changes from the assumed stoichiometric air-fuel ratio. There are cases in which the air-fuel ratio falls outside the effective purifying range. Therefore, when mixed liquid fuel is used, it is desirable that the mixing ratio of each fuel component in the mixed liquid fuel can be estimated.

  As techniques for identifying liquid fuel, those disclosed in Patent Documents 1 and 2 below are disclosed. In Patent Document 1, an identification sensor unit arranged facing a flow path of a liquid to be measured (liquid fuel) belonging to a hydrocarbon liquid or an alcohol liquid is an indirectly heated type including a heating element and a temperature sensing element. A liquid type detection unit and a liquid temperature detection unit that detects the temperature of the liquid to be measured are included. Furthermore, a single pulse voltage is applied to the heating element of the indirectly heated liquid type detection unit to generate heat, and the temperature sensing element and the liquid temperature detection unit of the indirectly heated liquid type detection unit are included. An identification calculation unit that identifies the liquid to be measured based on the output of the liquid type detection circuit is provided. The discriminating operation unit is a liquid type-corresponding first voltage value corresponding to a difference between the initial temperature of the temperature sensing element and the first temperature after the first pulse application from the start of the single pulse application when the heating element generates heat. And the second voltage value corresponding to the liquid type corresponding to the difference between the initial temperature of the temperature sensor and the second temperature at the second time longer than the first time from the start of the single pulse application, Identify. In Patent Document 1, there is a correlation between the first voltage value corresponding to the liquid type and the thermal conductivity of the liquid to be measured, and a correlation between the second voltage value corresponding to the liquid type and the kinematic viscosity of the liquid to be measured is used. Thus, the liquid to be measured is identified.

  Further, in Patent Document 2, light is incident on a prism from a light emitting element, total reflection is performed on a prism surface that is in contact with liquid fuel, and the total reflected light is received by a light receiving element. To detect. At that time, when the refractive index of the liquid fuel changes, the total reflection angle changes, and thus the total reflected light amount changes. That is, when the concentration of liquid fuel, for example, the mixing ratio of gasoline and methanol changes, the refractive index changes, so the concentration of methanol is estimated by detecting the total amount of reflected light.

JP 2005-214856 A Japanese Patent Laid-Open No. 4-194730

  In order to identify liquid fuel in Patent Documents 1 and 2, it is necessary to separately provide a dedicated device for identifying liquid fuel in the fuel path from the fuel tank to the internal combustion engine. For this reason, the configuration for identifying liquid fuel is complicated, and it is difficult to easily identify liquid fuel.

  An object of the present invention is to easily estimate a mixing ratio of a first liquid fuel and a second liquid fuel in an internal combustion engine using a mixed liquid fuel obtained by mixing a first liquid fuel and a second liquid fuel. .

  The internal combustion engine fuel type estimation apparatus and internal combustion engine control apparatus according to the present invention employ the following means in order to achieve the above-described object.

  A fuel type estimation device for an internal combustion engine according to the present invention is an internal combustion engine in which a mixed liquid fuel obtained by mixing a first liquid fuel and a second liquid fuel having different latent heats of vaporization is injected from a fuel injection device into an intake passage. A fuel type estimation device for an internal combustion engine that estimates a mixing ratio of fuel and second liquid fuel, an upstream intake temperature acquisition unit that acquires an intake air temperature upstream of the fuel injection device, and a downstream side of the fuel injection device The first liquid is based on a comparison result between the downstream intake temperature acquisition unit that acquires the intake air temperature at the intake air and the intake air temperature acquired by the upstream intake temperature acquisition unit and the intake air temperature acquired by the downstream intake temperature acquisition unit. The gist is to include a mixing ratio estimation unit that estimates a mixing ratio of the fuel and the second liquid fuel.

  The fuel type estimation apparatus for an internal combustion engine according to the present invention is an internal combustion engine that injects a mixed liquid fuel, which is a mixture of a first liquid fuel and a second liquid fuel having different latent heats of vaporization, from a fuel injection device to an intake passage. A fuel type estimation device for an internal combustion engine that estimates a mixing ratio of one liquid fuel and a second liquid fuel, an upstream side wall temperature acquisition unit that acquires an intake passage wall temperature upstream of the fuel injection device, and a fuel injection device The downstream side wall temperature acquisition unit that acquires the intake passage wall temperature on the further downstream side, and the comparison result between the intake passage wall temperature acquired by the upstream side wall temperature acquisition unit and the intake passage wall temperature acquired by the downstream side wall temperature acquisition unit The gist of the present invention is to include a mixing ratio estimation unit that estimates a mixing ratio of the first liquid fuel and the second liquid fuel.

  The fuel type estimation apparatus for an internal combustion engine according to the present invention is an internal combustion engine that injects a mixed liquid fuel, which is a mixture of a first liquid fuel and a second liquid fuel having different latent heats of vaporization, from a fuel injection device to an intake passage. A fuel type estimation device for an internal combustion engine that estimates a mixing ratio of one liquid fuel and a second liquid fuel, a downstream intake temperature acquisition unit that acquires an intake temperature downstream from the fuel injection device, and a downstream intake temperature And a mixing ratio estimation unit that estimates a mixing ratio of the first liquid fuel and the second liquid fuel based on a change in intake air temperature before and after the start of injection of the mixed liquid fuel acquired by the acquisition unit. And

  The fuel type estimation apparatus for an internal combustion engine according to the present invention is an internal combustion engine that injects a mixed liquid fuel, which is a mixture of a first liquid fuel and a second liquid fuel having different latent heats of vaporization, from a fuel injection device to an intake passage. A fuel type estimation device for an internal combustion engine that estimates a mixing ratio of one liquid fuel and a second liquid fuel, a downstream side wall temperature acquisition unit that acquires an intake passage wall temperature downstream of the fuel injection device, and a downstream side wall temperature A mixing ratio estimation unit that estimates a mixing ratio of the first liquid fuel and the second liquid fuel based on a change in the temperature of the intake passage wall before and after the start of injection of the mixed liquid fuel acquired by the acquisition unit. Is the gist.

  Further, the fuel type estimation device for an internal combustion engine according to the present invention provides a mixed liquid fuel obtained by mixing the first liquid fuel and the second liquid fuel having different latent heats of vaporization from the fuel injection device to the intake passage or in the intake stroke. A fuel type estimation device for an internal combustion engine that estimates a mixing ratio of a first liquid fuel and a second liquid fuel in an internal combustion engine that injects into the engine, a throttle opening acquisition unit that acquires a throttle opening, and intake air intake A first liquid fuel and a second liquid fuel based on the intake air amount acquisition unit that acquires the amount, the throttle opening acquired by the throttle opening acquisition unit, and the intake air intake amount acquired by the intake air amount acquisition unit; And a mixing ratio estimation unit that estimates the mixing ratio.

  In one aspect of the present invention, it is preferable that the first liquid fuel is a hydrocarbon fuel and the second liquid fuel is an alcohol fuel.

  An internal combustion engine control apparatus according to the present invention is an internal combustion engine control apparatus including the internal combustion engine fuel type estimation apparatus according to the present invention, wherein the first liquid fuel and the second liquid fuel estimated by the mixture ratio estimation unit The gist is to control one or more of the air-fuel ratio and the ignition timing based on the mixing ratio with the liquid fuel.

  According to the present invention, in the internal combustion engine using the mixed liquid fuel obtained by mixing the first liquid fuel and the second liquid fuel, a device dedicated to the mixing ratio of the first liquid fuel and the second liquid fuel is separately provided. And can be estimated easily.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

“Embodiment 1”
FIG. 1 is a diagram illustrating a schematic configuration of a control device including a fuel type estimation device for an internal combustion engine according to Embodiment 1 of the present invention, together with an internal combustion engine 10 that is a control target. The internal combustion engine 10 uses, as a fuel, a mixed liquid fuel obtained by mixing a first liquid fuel and a second liquid fuel having different latent heats of evaporation. Specific examples of the first liquid fuel include hydrocarbon fuels such as gasoline, and specific examples of the second liquid fuel include evaporative latent heat of gasoline, such as methanol, ethanol, and butanol. Mention can be made of large alcoholic fuels.

  In the fuel tank 12, a mixed liquid fuel obtained by mixing gasoline (hydrocarbon fuel) and alcohol fuel (for example, ethanol) is stored. The mixed liquid fuel stored in the fuel tank 12 is supplied to an injector (fuel injection device) 22 by a pump. An injector 22 facing the intake passage 20 (inside the intake pipe) injects the mixed liquid fuel supplied from the fuel tank 12 into the intake passage 20. Here, the mixed liquid fuel is injected toward the downstream side of the intake passage 20. The mixed liquid fuel injected from the injector 22 evaporates upon receiving heat from the surrounding gas and the intake pipe wall, and is introduced into the cylinder 11 together with air during the intake stroke. The internal combustion engine 10 generates power by burning a mixture of mixed fuel (gasoline and alcohol fuel) and air in the cylinder 11 by spark discharge of the spark plug 18. The exhaust gas after combustion is discharged from the cylinder 11 to the exhaust passage 21 (in the exhaust pipe) in the exhaust stroke, and is purified by the exhaust catalyst 30 provided as an exhaust purification device. The exhaust gas after combustion contains nitrogen oxides (NOx) and the like, and the nitrogen oxides and the like in the exhaust gas are purified by the exhaust catalyst 30.

  Since ethanol (alcohol-based fuel) has a higher octane number than gasoline, the higher the proportion of ethanol contained in the mixed liquid fuel, the higher the octane number of the entire mixed liquid fuel, and the higher the knock resistance. However, in the case of using a mixed liquid fuel in which ethanol is mixed with gasoline, the mixing ratio of gasoline and ethanol in the mixed liquid fuel supplied into the fuel tank 12 is not always constant, and the assumed mixing A mixed liquid fuel having a different ratio may be supplied into the fuel tank 12. Further, the mixing ratio of the mixed liquid fuel injected from the injector 22 may change due to separation of the fuel components of the mixed liquid fuel supplied into the fuel tank 12. For example, if the mixing ratio of ethanol in the mixed liquid fuel injected from the injector 22 is lower than the assumed mixing ratio, knocking is likely to occur because the octane number of the entire mixed liquid fuel becomes low. Further, when the mixing ratio of ethanol in the mixed liquid fuel injected from the injector 22 changes from the assumed mixing ratio, the stoichiometric air-fuel ratio of the entire mixed liquid fuel changes from the assumed stoichiometric air-fuel ratio. In some cases, the fuel ratio falls outside the air-fuel ratio range that can be effectively purified by the exhaust catalyst 30. Therefore, in the present embodiment, the mixing ratio of gasoline and ethanol in the mixed liquid fuel injected from the injector 22 is estimated. Then, based on the estimated mixture ratio, one or more of the ignition timing of the air-fuel mixture by the spark plug 18 and the air-fuel ratio of the air-fuel mixture is controlled. Hereinafter, a configuration example for that purpose will be described.

  The upstream intake air temperature sensor 42 is provided facing the upstream side of the injector 22 in the intake passage 20, and the intake air temperature upstream of the injector 22 (fuel injection position) (hereinafter referred to as upstream intake air temperature). Tiu is detected. In the example shown in FIG. 1, the upstream side intake temperature sensor 42 is provided facing the position downstream of the throttle valve 17 in the intake passage 20, and the upstream side intake temperature Tiu is set at a position downstream of the throttle valve 17. To detect. The downstream-side intake air temperature sensor 44 is attached so as to face a position downstream of the injector 22 in the intake passage 20, and the intake air temperature downstream of the injector 22 (fuel injection position) (hereinafter referred to as downstream intake air temperature). Tid is detected. The engine speed sensor 46 detects the rotational speed (engine speed) Ne of the internal combustion engine 10. The throttle opening sensor 48 detects the opening (throttle opening) A of the throttle valve 17. The electronic control unit (ECU) 40 is configured as a microprocessor centered on a CPU, and includes a ROM that stores a processing program, a RAM that temporarily stores data, and an input / output port. A signal indicating the upstream intake temperature Tiu detected by the upstream intake temperature sensor 42, a signal indicating the downstream intake temperature Tid detected by the downstream intake temperature sensor 44, and an engine speed detected by the engine speed sensor 46 A signal indicating Ne and a signal indicating the throttle opening A detected by the throttle opening sensor 48 are input to the electronic control unit 40.

  The electronic control unit 40 can be configured to include a mixture ratio estimation unit 52, an ignition timing control unit 54, and an air-fuel ratio control unit 56, for example, as shown in the functional block in FIG. The mixing ratio estimation unit 52 performs injection from the injector 22 based on the comparison result between the upstream intake temperature Tiu acquired by the upstream intake temperature sensor 42 and the downstream intake temperature Tid acquired by the downstream intake temperature sensor 44. The mixing ratio of gasoline (first liquid fuel) and alcohol-based fuel (second liquid fuel) in the mixed liquid fuel thus obtained is estimated. The ignition timing control unit 54 controls the ignition timing of the air-fuel mixture by the spark plug 18 based on the mixture ratio of gasoline and alcohol fuel estimated by the mixture ratio estimation unit 52. The air-fuel ratio control unit 56 controls the injection amount of the mixed liquid fuel from the injector 22 based on the mixture ratio of gasoline and alcohol fuel estimated by the mixture ratio estimation unit 52, so that the air-fuel ratio of the mixture is increased. To control.

  Since the mixed liquid fuel injected from the injector 22 into the intake passage 20 is evaporated by receiving ambient gas and heat from the intake pipe wall, the intake air temperature on the downstream side of the injector 22 decreases with the evaporation of the fuel. Therefore, as shown in FIG. 2, the upstream intake temperature Tiu detected by the upstream intake temperature sensor 42 is hardly affected by the evaporation of the fuel and hardly changes before and after the fuel is injected into the intake passage 20. On the other hand, the downstream side intake temperature Tid detected by the downstream side intake temperature sensor 44 decreases as the fuel injected into the intake passage 20 evaporates. Further, as the latent heat of vaporization of the fuel injected into the intake passage 20 increases, the amount of decrease in the downstream intake air temperature Tid before and after the fuel is injected increases, and the upstream intake air temperature Tiu and the downstream intake air after the fuel injection starts. The temperature difference Tiu−Tid with the temperature Tid increases.

  Alcohol fuels such as methanol and ethanol have a greater latent heat of vaporization than gasoline. For this reason, the higher the mixing ratio of the alcohol-based fuel in the mixed liquid fuel injected into the intake passage 20, the lower the downstream intake temperature Tid before and after the fuel is injected, and the upstream intake air after the start of fuel injection. The temperature difference Tiu−Tid between the temperature Tiu and the downstream intake air temperature Tid increases. Therefore, the mixing ratio estimation unit 52 calculates the mixing ratio of gasoline and alcohol-based fuel in the mixed liquid fuel based on the temperature difference Tiu−Tid between the upstream intake temperature Tiu and the downstream intake temperature Tid after the start of fuel injection. Can be estimated. As the temperature difference Tiu−Tid here, for example, a temperature difference between the upstream intake air temperature Tiu and the downstream intake air temperature Tid after a predetermined time τ has elapsed from the start of fuel injection can be used. It is also possible to use the temperature difference when the temperature difference between the upstream intake temperature Tiu and the downstream intake temperature Tid is maximized later (the downstream intake temperature Tid is the lowest). The table below shows a comparison of the latent heat of vaporization (kJ / kg) of isooctane, which is a typical component in gasoline, and methanol, ethanol, and butanol, which are typical alcohols. FIG. 3 shows an example in which the relationship of the temperature difference Tiu-Tid at τ after the start of fuel injection with respect to the mixing ratio of ethanol in the mixed liquid fuel of gasoline and ethanol is shown. As shown in FIG. 3, it can be seen that the temperature difference Tiu-Tid increases as the mixing ratio of ethanol increases.

  When estimating the mixing ratio of gasoline and alcohol fuel in the mixed liquid fuel, for example, as shown in FIG. 3, the relationship between the mixing ratio of alcohol fuel and the temperature difference Tiu-Tid after the start of fuel injection is expressed. A characteristic map is created in advance by experiments, calculations, and the like, and stored in the mixture ratio characteristic storage unit 58 (storage device) in the electronic control unit 40. The mixing ratio estimation unit 52 calculates the mixing ratio of the alcohol-based fuel corresponding to the given temperature difference Tiu-Tid in the characteristic map stored in the mixing-ratio characteristic storage unit 58, so that the gasoline and the alcohol-based fuel are calculated. And estimate the mixing ratio.

  However, the temperature difference Tiu−Tid is also affected by the engine speed Ne, the engine load (throttle opening) A, and the upstream intake air temperature Tiu. Therefore, the characteristic map showing the relationship between the mixing ratio of the alcohol-based fuel and the temperature difference Tiu-Tid after the start of fuel injection is based on each engine speed Ne, engine load (throttle opening) A, and upstream intake temperature Tiu (or A mixture ratio characteristic created for each engine speed Ne, engine load (throttle opening) A, and upstream intake air temperature Tiu (or any one of them). It is preferable to store in the storage unit 58. Then, the mixture ratio estimation unit 52 displays a characteristic map corresponding to the given engine speed Ne, engine load (throttle opening) A, and upstream intake air temperature Tiu (or any one or more of them) as a mixture ratio characteristic. It is preferable to read out from the storage unit 58 and calculate the alcohol fuel mixing ratio corresponding to the temperature difference Tiu-Tid in the read characteristic map. In this way, the mixture ratio estimation unit 52, in addition to the temperature difference Tiu−Tid after the start of fuel injection, the engine speed Ne, the engine load (throttle opening) A, and the upstream intake air temperature Tiu (or any one of them). It is preferable to estimate the mixing ratio of gasoline and alcohol-based fuel based on one or more).

  As described above, since the mixing ratio of gasoline and alcohol-based fuel in the mixed liquid fuel supplied into the fuel tank 12 is not necessarily constant, the mixing ratio of gasoline and alcohol-based fuel is, for example, the ratio to the fuel tank 12. It becomes easy to change before and after refueling. Therefore, it is preferable that the mixing ratio estimation unit 52 estimate the mixing ratio of gasoline and alcohol-based fuel in the mixed liquid fuel immediately after the internal combustion engine 10 is started after the mixed liquid fuel is supplied into the fuel tank 12. . At this time, whether or not the mixed liquid fuel has been supplied into the fuel tank 12 is determined based on a detection value of a sensor attached to the fuel tank 12 for detecting the remaining amount of fuel in the fuel tank 12, for example. can do. However, since the mixing ratio of the mixed liquid fuel injected from the injector 22 may change due to separation of the fuel components of the mixed liquid fuel supplied into the fuel tank 12, the mixing ratio estimation unit 52 It is also preferable to estimate the mixing ratio of the mixed liquid fuel every predetermined time.

  After the mixture ratio is estimated by the mixture ratio estimation unit 52, the ignition timing control unit 54 controls the ignition timing of the air-fuel mixture by the spark plug 18 based on the estimated mixture ratio. As mentioned above, since alcohol-based fuels such as ethanol have a higher octane number than gasoline, if the mixing ratio of alcohol-based fuel in the mixed liquid fuel is low, knocking is likely to occur due to the lower octane number of the entire mixed liquid fuel. Become. Therefore, it is preferable that the ignition timing control unit 54 retards the ignition timing of the air-fuel mixture by the spark plug 18 with respect to the decrease in the mixing ratio of the alcohol-based fuel estimated by the mixing ratio estimation unit 52. This can prevent knocking. Further, the ignition timing control unit 54 determines the ignition timing when the mixing ratio of the alcohol-based fuel estimated by the mixing ratio estimation unit 52 is lower than a predetermined ratio (than when the estimated mixing ratio is a predetermined ratio). And the ignition timing is advanced when the mixing ratio of the alcohol-based fuel estimated by the mixing ratio estimation unit 52 is higher than a predetermined ratio (than when the estimated mixing ratio is a predetermined ratio). You can also

  Further, after the mixture ratio is estimated by the mixture ratio estimation unit 52, the air-fuel ratio control unit 56 controls the air-fuel ratio of the air-fuel mixture based on the estimated mixture ratio. As described above, when the mixing ratio of the alcohol-based fuel in the mixed liquid fuel changes from the assumed mixing ratio, the theoretical air-fuel ratio of the entire mixed liquid fuel changes from the assumed theoretical air-fuel ratio. May deviate from the air-fuel ratio range that can be effectively purified by the exhaust catalyst 30. Therefore, it is preferable that the air-fuel ratio control unit 56 lowers the air-fuel ratio of the air-fuel mixture with respect to the increase in the alcohol-based fuel mixture ratio estimated by the mixture ratio estimation unit 52. As a result, it is possible to prevent the air-fuel ratio of the air-fuel mixture from deviating from the air-fuel ratio range that can be effectively purified by the exhaust catalyst 30. In addition, the air-fuel ratio control unit 56, when the mixing ratio of the alcohol-based fuel estimated by the mixing ratio estimation unit 52 is lower than a predetermined ratio (than when the estimated mixing ratio is a predetermined ratio). When the mixture ratio of the alcohol-based fuel estimated by the mixture ratio estimation unit 52 is higher than a predetermined ratio, the air-fuel mixture is empty (than when the estimated mixture ratio is a predetermined ratio). The fuel ratio can also be lowered. The air-fuel ratio control unit 56 may increase the fuel injection amount from the injector 22 when lowering the air-fuel ratio, or may decrease the opening of the throttle valve 17 in the case of an electric throttle. Good. Similarly, when increasing the air-fuel ratio, the fuel injection amount from the injector 22 may be decreased, or in the case of an electric throttle, the opening of the throttle valve 17 may be increased.

  In the present embodiment described above, the mixture ratio between gasoline and alcohol-based fuel in the mixed liquid fuel is estimated based on the temperature difference Tiu-Tid between the upstream intake air temperature Tiu and the downstream intake air temperature Tid after the start of fuel injection. is doing. In that case, since the mixing ratio of the mixed liquid fuel is estimated using an intake air temperature sensor normally provided in the internal combustion engine 10, the mixing ratio of the mixed liquid fuel is separately determined using a dedicated device or a special sensor. It can be estimated easily without providing. Further, knocking can be prevented by controlling the ignition timing based on the estimated mixing ratio of the mixed liquid fuel. Further, by controlling the air-fuel ratio of the mixture based on the estimated mixture ratio of the mixed liquid fuel, it is possible to prevent the air-fuel ratio of the mixture from deviating from the air-fuel ratio range that can be effectively purified by the exhaust catalyst 30. .

  As described above, the higher the mixing ratio of the alcohol-based fuel in the mixed liquid fuel injected into the intake passage 20, the greater the decrease in the downstream intake temperature Tid before and after the fuel is injected. Therefore, in the present embodiment, the mixture ratio estimation unit 52 changes the downstream intake temperature Tid before and after the start of the injection of the mixed liquid fuel, which is acquired by the downstream intake temperature sensor 44 instead of the temperature difference Tiu−Tid. Based on ΔTid, the mixing ratio of gasoline and alcohol fuel in the mixed liquid fuel can also be estimated. As the amount of change ΔTid of the downstream intake temperature here, for example, a temperature difference between the downstream intake temperature immediately before the start of fuel injection and the downstream intake temperature after a predetermined time τ has elapsed since the start of fuel injection may be used. It is also possible to use the difference between the downstream intake temperature immediately before the start of fuel injection and the minimum value of the downstream intake temperature after the start of fuel injection. When estimating the mixing ratio of the mixed liquid fuel, a characteristic map representing the relationship between the mixing ratio of the alcohol-based fuel and the amount of change ΔTid in the downstream side intake air temperature before and after the start of fuel injection is prepared in advance by experiments or calculations. Then, it is stored in the mixing ratio characteristic storage unit 58 in the electronic control unit 40. The mixing ratio estimation unit 52 calculates the mixing ratio of alcohol-based fuel corresponding to the given downstream side intake air temperature change amount ΔTid in the characteristic map stored in the mixing ratio characteristic storage unit 58. Further, the characteristic map showing the relationship between the mixing ratio of the alcohol-based fuel and the change amount ΔTid of the downstream side intake air temperature before and after the start of fuel injection shows each engine speed Ne, the engine load (throttle opening) A, and the upstream side intake air temperature. It is preferable to store them in the mixing ratio characteristic storage unit 58 in association with Tiu (or any one or more of them). Then, the mixture ratio estimation unit 52 displays a characteristic map corresponding to the given engine speed Ne, engine load (throttle opening) A, and upstream intake air temperature Tiu (or any one or more of them) as a mixture ratio characteristic. It is preferable to read out from the storage unit 58 and calculate the alcohol-based fuel mixing ratio corresponding to the given downstream side intake air temperature change amount ΔTid in the read characteristic map. When the mixing ratio of the mixed liquid fuel is estimated based on the change amount ΔTid of the downstream intake temperature before and after the start of the mixed liquid fuel injection, the upstream intake temperature sensor 42 can be omitted.

“Embodiment 2”
FIG. 4 is a diagram illustrating a schematic configuration of a control device including a fuel type estimation device for an internal combustion engine according to the second embodiment of the present invention. In the following description of the second embodiment, the same or corresponding components as those of the first embodiment are denoted by the same reference numerals, and the description of the components that are not described is the same as that of the first embodiment.

  In the present embodiment, an upstream side wall temperature sensor 62 and a downstream side wall temperature sensor 64 are attached instead of the upstream side intake temperature sensor 42 and the downstream side intake temperature sensor 44 as compared with the first embodiment. The upstream side wall temperature sensor 62 detects an intake passage wall temperature (hereinafter referred to as an upstream side wall temperature) Twu upstream of the injector 22 (fuel injection position). The downstream side wall temperature sensor 64 detects an intake passage wall temperature (hereinafter referred to as a downstream side wall temperature) Twd on the downstream side of the injector 22 (fuel injection position). Here, in order to improve the responsiveness of wall temperature detection, it is possible to make the portion of the intake passage wall where the wall temperatures Twu and Twd are measured have a thin film structure. It is also possible to use a resin material for the portion of the intake passage wall for measuring the wall temperatures Twu and Twd. A signal indicating the upstream side wall temperature Twu detected by the upstream side wall temperature sensor 62 and a signal indicating the downstream side wall temperature Twd detected by the downstream side wall temperature sensor 64 are input to the electronic control unit 40. The mixing ratio estimator 52 is a liquid mixture ejected from the injector 22 based on a comparison result between the upstream side wall temperature Twu acquired by the upstream side wall temperature sensor 62 and the downstream side wall temperature Twd acquired by the downstream side wall temperature sensor 64. The mixing ratio of gasoline (first liquid fuel) and alcohol fuel (second liquid fuel) in the fuel is estimated.

  The mixed liquid fuel injected from the injector 22 into the intake passage 20 evaporates in response to ambient gas and heat from the intake pipe wall, so that the intake passage wall temperature on the downstream side of the injector 22 decreases as the fuel evaporates. . Therefore, as shown in FIG. 2, the upstream side wall temperature Twu detected by the upstream side wall temperature sensor 62 is hardly affected by the evaporation of the fuel and hardly changes before and after the fuel is injected into the intake passage 20. Thus, the downstream side wall temperature Twd detected by the downstream side wall temperature sensor 64 decreases as the fuel injected into the intake passage 20 evaporates. Furthermore, as the mixing ratio of the alcohol-based fuel in the mixed liquid fuel injected into the intake passage 20 is higher and the latent heat of vaporization of the fuel is larger, the decrease in the downstream side wall temperature Twd before and after the fuel is injected becomes larger, and the fuel injection starts. The temperature difference Twu−Twd between the upstream side wall temperature Twu and the downstream side wall temperature Twd later increases. Therefore, the mixing ratio estimation unit 52 estimates the mixing ratio of gasoline and alcohol-based fuel in the mixed liquid fuel based on the temperature difference Twu-Twd between the upstream side wall temperature Twu and the downstream side wall temperature Twd after the start of fuel injection. be able to. As for the temperature difference Twu-Twd here, for example, the temperature difference between the upstream side wall temperature Twu and the downstream side wall temperature Twd after a lapse of a predetermined time τ from the start of fuel injection can be used. It is also possible to use the temperature difference when the temperature difference between the sidewall temperature Twu and the downstream sidewall temperature Twd becomes maximum (the downstream sidewall temperature Twd becomes the lowest). It should be noted that the measurement position of the downstream side wall temperature Twd by the downstream side wall temperature sensor 64 is more effective when the position where the fuel injected from the injector 22 collides is selected.

  When estimating the mixing ratio of the mixed liquid fuel, a characteristic map representing the relationship between the mixing ratio of the alcohol-based fuel and the temperature difference Twu-Twd before and after the start of fuel injection is created in advance by experiments, calculations, etc., and electronic control is performed. This is stored in the mixing ratio characteristic storage unit 58 in the apparatus 40. The mixing ratio estimation unit 52 calculates the mixing ratio of the alcohol-based fuel corresponding to the given temperature difference Twu−Twd in the characteristic map stored in the mixing ratio characteristic storage unit 58. Further, the characteristic map showing the relationship between the mixing ratio of the alcohol-based fuel and the temperature difference Twu-Twd before and after the start of fuel injection includes each engine speed Ne, engine load (throttle opening) A, and upstream intake air temperature Tiu (or It is preferable to store them in the mixing ratio characteristic storage unit 58 in association with one or more of them. Then, the mixture ratio estimation unit 52 displays a characteristic map corresponding to the given engine speed Ne, engine load (throttle opening) A, and upstream intake air temperature Tiu (or any one or more of them) as a mixture ratio characteristic. It is preferable to read out from the storage unit 58 and to calculate the alcohol-based fuel mixture ratio corresponding to the given temperature difference Twu-Twd in the read characteristic map.

  Also in the present embodiment described above, as in the first embodiment, the mixing ratio of gasoline and alcohol fuel in the mixed liquid fuel can be easily estimated without separately providing a dedicated device or a special sensor.

  Also in the present embodiment, the mixture ratio estimation unit 52 uses the change amount ΔTwd of the downstream side wall temperature Twd before and after the start of the injection of the mixed liquid fuel acquired by the downstream side wall temperature sensor 64 instead of the temperature difference Twu−Twd. Based on this, it is possible to estimate the mixing ratio of gasoline and alcohol fuel in the mixed liquid fuel. As the amount of change ΔTwd of the downstream sidewall temperature here, for example, a temperature difference between the downstream sidewall temperature immediately before the start of fuel injection and the downstream sidewall temperature after a predetermined time τ has elapsed from the start of fuel injection can be used. A difference between the downstream side wall temperature just before the start of fuel injection and the minimum value of the downstream side wall temperature after the start of fuel injection can also be used. When estimating the mixing ratio of the mixed liquid fuel, a characteristic map representing the relationship between the mixing ratio of the alcohol-based fuel and the amount of change ΔTwd in the downstream side wall temperature before and after the start of fuel injection is created in advance by experiment, calculation, etc. This is stored in the mixing ratio characteristic storage unit 58 in the electronic control unit 40. The mixing ratio estimation unit 52 calculates the mixing ratio of the alcohol-based fuel corresponding to the given amount of change ΔTwd of the downstream side wall temperature in the characteristic map stored in the mixing ratio characteristic storage unit 58. Further, the characteristic map showing the relationship between the mixing ratio of alcohol-based fuel and the amount of change ΔTwd of the downstream side wall temperature before and after the start of fuel injection shows each engine speed Ne, engine load (throttle opening) A, and upstream intake temperature Tiu. (Or any one or more of them) is preferably stored in the mixing ratio characteristic storage unit 58 in association with each other. Then, the mixture ratio estimation unit 52 displays a characteristic map corresponding to the given engine speed Ne, engine load (throttle opening) A, and upstream intake air temperature Tiu (or any one or more of them) as a mixture ratio characteristic. It is preferable to read out from the storage unit 58 and calculate the alcohol-based fuel mixing ratio corresponding to the given downstream side wall temperature change ΔTwd in the read characteristic map. When the mixing ratio of the mixed liquid fuel is estimated based on the change amount ΔTwd of the downstream side wall temperature before and after the start of the injection of the mixed liquid fuel, the upstream side wall temperature sensor 62 can be omitted.

“Embodiment 3”
FIG. 5 is a diagram illustrating a schematic configuration of a control device including a fuel type estimation device for an internal combustion engine according to Embodiment 3 of the present invention, together with the internal combustion engine 10 that is a control target. In the following description of the third embodiment, the same or corresponding components as those of the first and second embodiments are denoted by the same reference numerals, and the description of the components that are not described is the same as that of the first and second embodiments.

  In the present embodiment, the downstream intake air temperature sensor 44 is omitted as compared with the first embodiment, and an intake air amount sensor (intake intake air amount sensor) that detects an intake air amount (intake intake air amount) IA of the internal combustion engine 10. 66 is attached. In the example shown in FIG. 5, the intake air amount sensor 66 is provided at a position upstream of the injector 22 and the throttle valve 17 in the intake passage 20 and is suctioned at a position upstream of the injector 22 and the throttle valve 17. The air amount IA is detected. Further, as in the first embodiment, an upstream side intake air temperature sensor 42, an engine speed sensor 46, and a throttle opening sensor 48 are attached. A signal indicating the intake air amount IA detected by the intake air amount sensor 66, a signal indicating the upstream intake air temperature Tiu detected by the upstream intake air temperature sensor 42, and the engine speed Ne detected by the engine speed sensor 46 are used. A signal indicating the throttle opening A detected by the throttle opening sensor 48 is input to the electronic control unit 40. Based on the throttle opening A acquired by the throttle opening sensor 48 and the intake air amount IA acquired by the intake air amount sensor 66, the mixture ratio estimation unit 52 is a gasoline in the mixed liquid fuel injected from the injector 22. A mixing ratio between the (first liquid fuel) and the alcohol fuel (second liquid fuel) is estimated.

  Even in the case of the same intake passage pressure, when the intake gas temperature or the in-cylinder gas temperature in the intake stroke decreases, the charging efficiency increases and the intake air amount IA increases. That is, even at the same throttle opening A, the intake air amount IA increases as the mixing ratio of the alcohol-based fuel in the mixed liquid fuel increases and the latent heat of vaporization increases. Therefore, the mixture ratio estimation unit 52 can estimate the mixture ratio of gasoline and alcohol fuel in the mixed liquid fuel based on the relationship between the throttle opening A and the intake air amount IA. FIG. 6 shows an example in which the relationship between the throttle opening A and the intake air amount IA is calculated while changing the mixing ratio of ethanol in the mixed liquid fuel of gasoline and ethanol. As shown in FIG. 6, it can be seen that the intake air amount IA for the same throttle opening A increases as the mixing ratio of ethanol increases.

  When estimating the mixing ratio of the mixed liquid fuel, for example, as shown in FIG. 6, a characteristic map showing the relationship of the mixing ratio of the alcohol-based fuel to the throttle opening A and the intake air amount IA is obtained in advance by experiments or calculations. It is created and stored in the mixing ratio characteristic storage unit 58 in the electronic control unit 40. The mixing ratio estimation unit 52 calculates the mixing ratio of alcohol-based fuel corresponding to the given throttle opening A and intake air amount IA in the characteristic map stored in the mixing ratio characteristic storage unit 58, thereby Estimate the mixing ratio of alcohol fuel with alcohol.

  However, the relationship of the mixing ratio of the alcohol fuel to the throttle opening A and the intake air amount IA is also affected by the engine speed Ne and the upstream intake temperature Tiu. Therefore, a characteristic map showing the relationship of the mixing ratio of the alcohol-based fuel to the throttle opening A and the intake air amount IA is created for each engine speed Ne and upstream intake air temperature Tiu (or any one or more of them). The engine speed Ne and the upstream intake air temperature Tiu (or any one or more of them) are preferably stored in the mixing ratio characteristic storage unit 58. Then, the mixture ratio estimation unit 52 reads out the characteristic map corresponding to the given engine speed Ne and the upstream side intake air temperature Tiu (or any one or more of them) from the mixture ratio characteristic storage unit 58, and this read out. In the characteristic map, it is preferable to calculate the mixing ratio of the alcohol-based fuel corresponding to the given throttle opening A and intake air amount IA. As described above, the mixing ratio estimation unit 52 determines the gasoline and the fuel based on the engine speed Ne and the upstream intake temperature Tiu (or any one or more of them) in addition to the throttle opening A and the intake air amount IA. It is preferable to estimate the mixing ratio with the alcohol-based fuel.

  In the present embodiment described above, the mixing ratio of gasoline and alcohol fuel in the mixed liquid fuel is estimated based on the throttle opening A and the intake air amount IA. At that time, since the mixing ratio of the mixed liquid fuel is estimated by using the throttle opening sensor 48 and the intake air amount sensor 66 normally provided in the internal combustion engine 10, the mixing ratio of the mixed liquid fuel is dedicated. It is possible to easily estimate without providing a separate device or special sensor.

  In the above description of the third embodiment, the case where the mixed liquid fuel is injected into the intake passage 20 has been described. However, in the present embodiment, the internal combustion engine 10 may be a direct injection internal combustion engine that directly injects the mixed liquid fuel from the injector into the cylinder 11 during the intake stroke. Even in this case, the mixture ratio estimation unit 52 uses gasoline (first liquid fuel) and alcohol-based fuel (first liquid fuel) in the mixed liquid fuel injected into the cylinder 11 based on the throttle opening A and the intake air amount IA. 2 liquid fuel) can be estimated.

  In the above description of the first to third embodiments, a mixed liquid fuel obtained by mixing gasoline and alcohol fuel is used as a mixed liquid fuel obtained by mixing the first liquid fuel and the second liquid fuel having different latent heats of evaporation. The case where the mixing ratio of gasoline and alcohol fuel in the mixed liquid fuel is estimated has been described. However, in Embodiments 1 to 3, it is also possible to use liquid fuels other than gasoline and alcohol-based fuels as the first liquid fuel and the second liquid fuel having different latent heats of evaporation. For example, oxygen-containing fuels other than alcohol fuels can be used, and furans can also be used. In the first to third embodiments, the latent heat of vaporization of the two types of liquid fuels only needs to be different.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, and it can implement with a various form in the range which does not deviate from the summary of this invention. Of course.

It is a figure which shows schematic structure of the control apparatus provided with the fuel kind estimation apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention with the internal combustion engine which is a control object. It is a figure explaining the time change of the upstream intake temperature Tiu and the downstream intake temperature Tid (or the upstream side wall temperature Twu and the downstream side wall temperature Twd). It is a figure which shows the example which calculated the relationship of the temperature difference Tiu-Tid in (tau) after the fuel injection start with respect to the mixing ratio of ethanol. It is a figure which shows schematic structure of a control apparatus provided with the fuel seed | species estimation apparatus of the internal combustion engine which concerns on Embodiment 2 of this invention. It is a figure which shows schematic structure of the control apparatus provided with the fuel seed | species estimation apparatus of the internal combustion engine which concerns on Embodiment 3 of this invention with the internal combustion engine which is a control object. It is a figure which shows the example which calculated the relationship between the throttle opening A and the intake air amount IA, changing the mixing ratio of ethanol.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Internal combustion engine, 11 Cylinder, 12 Fuel tank, 17 Throttle valve, 18 Spark plug, 20 Intake passage, 21 Exhaust passage, 22 Injector, 30 Exhaust catalyst, 40 Electronic control unit, 42 Upstream intake temperature sensor, 44 Downstream intake Temperature sensor, 46 Engine speed sensor, 48 Throttle opening sensor, 52 Mixing ratio estimation unit, 54 Ignition timing control unit, 56 Air-fuel ratio control unit, 58 Mixing ratio characteristic storage unit, 62 Upstream side wall temperature sensor, 64 Downstream side wall temperature Sensor, 66 Intake air amount sensor.

Claims (7)

In an internal combustion engine that injects a mixed liquid fuel obtained by mixing a first liquid fuel and a second liquid fuel having different latent heats of evaporation from a fuel injection device into an intake passage, a mixing ratio of the first liquid fuel and the second liquid fuel is estimated. A fuel type estimation device for an internal combustion engine,
An upstream intake air temperature acquisition unit for acquiring intake air temperature upstream of the fuel injection device;
A downstream side intake air temperature acquisition unit for acquiring an intake air temperature downstream of the fuel injection device;
Mixing for estimating the mixing ratio of the first liquid fuel and the second liquid fuel based on the comparison result between the intake air temperature acquired by the upstream intake air temperature acquisition unit and the intake air temperature acquired by the downstream intake air temperature acquisition unit A ratio estimator;
A fuel type estimation device for an internal combustion engine, comprising: In an internal combustion engine that injects a mixed liquid fuel obtained by mixing a first liquid fuel and a second liquid fuel having different latent heats of vaporization from a fuel injection device into an intake passage, a mixing ratio of the first liquid fuel and the second liquid fuel is estimated. A fuel type estimation device for an internal combustion engine,
An upstream side wall temperature acquisition unit for acquiring an intake passage wall temperature upstream of the fuel injection device;
A downstream side wall temperature acquisition unit for acquiring an intake passage wall temperature on the downstream side of the fuel injection device;
Based on the comparison result between the intake passage wall temperature acquired by the upstream side wall temperature acquisition unit and the intake passage wall temperature acquired by the downstream side wall temperature acquisition unit, the mixing ratio of the first liquid fuel and the second liquid fuel is estimated. A mixing ratio estimation unit,
A fuel type estimation device for an internal combustion engine, comprising: In an internal combustion engine that injects a mixed liquid fuel obtained by mixing a first liquid fuel and a second liquid fuel having different latent heats of vaporization from a fuel injection device into an intake passage, a mixing ratio of the first liquid fuel and the second liquid fuel is estimated. A fuel type estimation device for an internal combustion engine,
A downstream side intake air temperature acquisition unit for acquiring an intake air temperature downstream of the fuel injection device;
A mixing ratio estimation unit that estimates a mixing ratio of the first liquid fuel and the second liquid fuel based on a change in the intake air temperature before and after the start of the injection of the mixed liquid fuel acquired by the downstream side intake temperature acquisition unit;
A fuel type estimation device for an internal combustion engine, comprising: In an internal combustion engine that injects a mixed liquid fuel obtained by mixing a first liquid fuel and a second liquid fuel having different latent heats of vaporization from a fuel injection device into an intake passage, a mixing ratio of the first liquid fuel and the second liquid fuel is estimated. A fuel type estimation device for an internal combustion engine,
A downstream side wall temperature acquisition unit for acquiring an intake passage wall temperature on the downstream side of the fuel injection device;
A mixing ratio estimation unit that estimates the mixing ratio of the first liquid fuel and the second liquid fuel based on the change in the intake passage wall temperature before and after the start of injection of the mixed liquid fuel, acquired by the downstream side wall temperature acquisition unit;
A fuel type estimation device for an internal combustion engine. In an internal combustion engine that injects a mixed liquid fuel obtained by mixing a first liquid fuel and a second liquid fuel having different latent heats of evaporation from a fuel injection device into an intake passage or into a cylinder during an intake stroke, A fuel type estimation device for an internal combustion engine that estimates a mixing ratio with liquid fuel,
A throttle opening acquisition unit for acquiring the throttle opening;
An intake air intake amount acquisition unit for acquiring the intake air intake amount;
A mixture ratio estimation unit that estimates a mixture ratio of the first liquid fuel and the second liquid fuel based on the throttle opening acquired by the throttle opening acquisition unit and the intake air intake amount acquired by the intake air intake amount acquisition unit When,
A fuel type estimation device for an internal combustion engine, comprising: A fuel type estimation device for an internal combustion engine according to any one of claims 1 to 5,
A fuel type estimation device for an internal combustion engine, wherein the first liquid fuel is a hydrocarbon fuel and the second liquid fuel is an alcohol fuel. An internal combustion engine control device comprising the internal combustion engine fuel type estimation device according to any one of claims 1 to 6,
A control device for an internal combustion engine that controls at least one of an air-fuel ratio and an ignition timing based on a mixing ratio of a first liquid fuel and a second liquid fuel estimated by a mixing ratio estimation unit.

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