JP2008082329A - Fuel injection control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device of an internal combustion engine capable of using multiple kinds of fuel for stably optimizing control of fuel supply in response to mixing rate of multiple fuels shortening engine starting time and capable of preventing the covering of a plug. <P>SOLUTION: An ECU 10 with a ROM 23 stores multiple reference fuel injection quantity maps corresponding to mixture concentrations of the multiple kinds of fuels. A control program of the CPU 21 stores which of the multiple reference fuel injection quantity map is used out of the maps in an EEP-ROM 24, performs starting control of an engine using the reference fuel injection quantity map which is used immediately before stopping previous time at the time of initiating the starting based on the stored maps and, at the same time, performs the starting control by gradually increasing the fuel injection quantity until the starting of an engine is finished. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel injection control device for an internal combustion engine that controls fuel supply to the internal combustion engine. In particular, the present invention relates to a fuel injection control device for a multi-fuel internal combustion engine that can be used by mixing a plurality of types of fuel.

  There is an internal combustion engine (engine) that operates by combustion of various fuels such as ethanol mixed with gasoline other than gasoline. In such an internal combustion engine, control for operating the internal combustion engine at an air-fuel ratio corresponding to the mixing ratio of various fuels is required.

For example, as a conventional technique related to a multifuel internal combustion engine, Patent Literature 1 describes a method for correcting a fuel injection time in a fuel injection device of a multifuel engine (formula (1) on page 3).
In Patent Document 2, the amount of fuel at start-up is gradually changed, the time during which the start of the internal combustion engine is detected is measured, and the type of fuel used (heavy fuel or light fuel) ) Is described (claim 1, paragraph 0005, and paragraph 0007).
JP 63-5131 A JP-A-5-65838

However, the above prior art has the following problems.
In general, refueling is performed when the engine is stopped. However, in a multi-fuel engine, when refueling, the amount of fuel to be refilled can be arbitrarily determined by the replenisher. ing. Therefore, the newly supplied fuel is mixed with the fuel remaining in the fuel tank in the tank, and the mixing ratio cannot be easily detected. Although it is technically possible to detect the mixing ratio by providing a fuel type sensor in a fuel tank or a fuel supply pipe to an internal combustion engine, the cost becomes very high.

  Although the technique described in Patent Document 1 corrects the fuel injection time, the basic injection time (Ti) determined from the engine speed (Ne) and the intake pipe absolute pressure (Pba) is constant. Therefore, depending on the type of fuel replenished by the driver and the mixing ratio, the plug may be worn (i.e., too much fuel is supplied, so that unburned gas that does not burn by ignition of the plug will adhere to the plug electrode. There is a problem that it becomes difficult to discharge.

  Moreover, although the technique described in Patent Document 2 can discriminate the fuel, there is a problem that it takes too much time to gradually change the fuel amount when starting the engine. Furthermore, in the technique described in Patent Document 2, although the fuel supply amount setting means is switched between heavy fuel and light fuel (described in paragraph 0006), engine operation by mixing various fuels is performed. Is not taken into account, and there is a problem that the engine cannot be stabilized after starting.

  The present invention has been made on the basis of the above-mentioned problem recognition, and performs stable optimum fuel injection (supply) control according to the mixing ratio of various fuels, shortens the starting time, and further plugs. It is an object of the present invention to provide a fuel injection control device for a multi-fuel internal combustion engine that can prevent fogging.

  In order to solve the above problems, the present invention has a start completion detecting means for detecting a start state of the internal combustion engine, and after the start completion is detected by the start completion detecting means, the fuel is determined according to the state of the internal combustion engine. In a fuel injection control device for an internal combustion engine for multi-fuel which determines an injection amount, a reference fuel injection amount map is stored, the start control of the internal combustion engine is performed using the reference fuel injection amount map, and the internal combustion engine is started. The fuel injection control device for an internal combustion engine for multi-fuels is characterized in that start control of the internal combustion engine is performed by gradually increasing the fuel injection amount until is completed.

The present invention further includes start completion detecting means (for example, step Sb13 in the embodiment) for detecting the start state of the internal combustion engine (for example, the engine 1 in the embodiment), and the start completion is performed by the start completion detecting means. In the fuel injection control device (for example, the ECU 10 in the embodiment) of the multifuel internal combustion engine that determines the fuel injection amount according to the state of the internal combustion engine, a plurality of fuels corresponding to the mixed concentration of the multifuel are detected. A reference fuel injection amount map is stored (for example, a reference fuel injection amount map stored in the ROM 23 in the embodiment), and which one of the plurality of reference fuel injection amount maps is used is stored. Based on this memory, the start control of the internal combustion engine is performed using the reference fuel injection amount map that was used immediately before the previous stop when starting. Utotomoni, gradually increasing the fuel injection quantity until the starting of the internal combustion engine is completed and starts control, it is a fuel injection control apparatus for a multi-fuel internal combustion engine according to claim.
As a result, by storing the reference fuel injection amount map used during normal operation, starting control is performed using the reference fuel injection amount map corresponding to the fuel mixture ratio before starting when restarting. Can be performed.

Further, according to the present invention, in the above-described invention, the fuel injection amount is increased when the fuel injection is not completed even though the fuel is injected a predetermined number of times with the reference fuel injection amount map used at the start of the start of cranking. It is characterized by that.
As a result, when the engine is not started due to cranking, the fuel injection amount can be gradually increased every time a certain number of injections is reached.

Further, according to the present invention, in the above-described invention, the fuel injection amount is increased when the start is not completed despite cranking by fuel injection for a predetermined time using the reference fuel injection amount map used at the start of the start. It is characterized by that.
As a result, when the engine is not started due to cranking, the fuel injection amount can be gradually increased every time a certain injection time elapses.

In the present invention described above, the reference fuel injection amount map may include three or more appropriate numbers (for example, 22%, 50%, 100%) of Pb corresponding to the mixing ratio of ethanol and gasoline. / Ne map.
This makes it possible to stably perform start-up control and control during normal operation by selecting an appropriate Pb / Ne map without adjusting the Pb / Ne map according to all the mixture ratios. Become.

Further, according to the present invention, in the above-described invention, an oxygen concentration sensor (for example, the O2 sensor 15 in the embodiment) that generates an output corresponding to the oxygen concentration in the exhaust gas is provided in an exhaust system of an internal combustion engine, and the oxygen The ethanol mixing ratio in the fuel is estimated from the output of the concentration sensor.
Thereby, it becomes possible to select and use one of the plurality of reference fuel injection amount maps based on the estimation result of the ethanol mixture ratio.

The present invention further includes start completion detection means for detecting the start state of the internal combustion engine, and after the start completion is detected by the start completion detection means, the fuel injection amount is determined according to the state of the internal combustion engine. In a fuel injection control device for an internal combustion engine for fuel, a plurality of reference fuel injection amount maps corresponding to a mixture concentration of various fuels are stored, and an internal combustion engine is used by using a reference fuel injection amount map having the smallest fuel injection amount at the start of startup. An internal combustion engine for multi-fuel, characterized by performing engine start control and switching to a reference fuel injection amount map with a larger fuel injection amount depending on the start state until the start of the internal combustion engine is completed A fuel injection control device for an engine.
Thereby, at the time of starting, it becomes possible to perform the starting control by gradually increasing the fuel injection amount from the state where the fuel injection amount is the smallest.

  Further, according to the present invention, in the above-described fuel injection control device, the fuel injection amount is gradually increased rather than the increment of the fuel injection amount at every initial predetermined time or every predetermined number of times when the fuel injection amount is gradually increased. The starting control is performed so that the increment of the fuel injection amount increases every predetermined time or every predetermined number of times.

  In the fuel injection control device, the present invention performs start control so that the increment of the fuel injection amount every predetermined time or every predetermined number of times when the fuel injection amount is gradually increased follows an exponential function. Features.

The present invention stores a plurality of reference fuel injection amount maps corresponding to the mixture concentration of various fuels, stores which map of the plurality of reference fuel injection amount maps is used, and stores the stored map. Based on the above, the start control of the internal combustion engine is performed using the reference fuel injection amount map used immediately before the stop at the start of the start, and the start control is performed by gradually increasing the fuel injection amount until the start of the internal combustion engine is completed. It was set as the structure which performs.
As a result, regardless of how much fuel is replenished during stoppage, the fuel pipe can be controlled by starting control using the reference fuel injection amount map used during normal operation before restarting. Since the fuel having the mixing ratio in the normal operation before the restart remains, the internal combustion engine can be started at an appropriate air-fuel ratio at the mixing ratio.

Further, according to the present invention, the fuel injection amount is increased when the reference fuel injection amount map used at the start of the start does not complete even though the fuel is injected a predetermined number of times and cranked.
As a result, the fuel injection amount can be gradually increased every time a certain number of injections is reached, so that the fuel mixture ratio in the fuel tank can be estimated while avoiding plug fogging. It is possible to start the internal combustion engine at a high air-fuel ratio.

Further, according to the present invention, the fuel injection amount is increased when the reference fuel injection amount map used at the start of the start does not complete even though the fuel is injected for a predetermined time and cranked.
As a result, the fuel injection amount can be gradually increased every time a certain injection time elapses, so that the fuel mixture ratio in the fuel tank can be estimated while avoiding the fogging of the plug. It becomes possible to start the internal combustion engine at an appropriate air-fuel ratio.

In the present invention, an oxygen concentration sensor that generates an output corresponding to the oxygen concentration in the exhaust gas is provided in the exhaust system of the internal combustion engine, and the ethanol mixing ratio in the fuel is estimated from the output of the oxygen concentration sensor.
As a result, any one of the plurality of reference fuel injection amount maps can be selected and used based on the estimation result of the ethanol mixture ratio, so that the internal combustion engine can be operated at an appropriate air-fuel ratio according to the ethanol mixture ratio. It becomes possible to drive.

Further, the present invention stores a plurality of reference fuel injection amount maps corresponding to the mixed concentrations of various fuels, and controls the start-up of the internal combustion engine using the reference fuel injection amount map with the smallest fuel injection amount at the start of starting. In addition, the start control is performed by switching to the reference fuel injection amount map having a larger fuel injection amount according to the start state until the start of the internal combustion engine is completed.
As a result, at the time of starting, since the starting control is performed by gradually increasing the fuel injection amount from the state where the fuel injection amount is the smallest, the fuel mixture ratio in the fuel tank can be estimated, and the plug fogging can be estimated. This makes it possible to start the internal combustion engine at an appropriate air-fuel ratio.

In the present invention, the starting control is performed such that the increment of the fuel injection amount in the latter period is larger than the increment of the fuel injection amount at every initial predetermined time or every predetermined number of times when the fuel injection amount is gradually increased. The configuration. Further, as one aspect thereof, the start control is performed such that the increment of the fuel injection amount every predetermined time or every predetermined number of times increases exponentially.
As a result, the amount of fuel does not increase too much in the early stage of the start where plug fogging is likely to occur, and the necessary fuel is replenished in the later stage of the start. In particular, when the temperature that greatly affects the vaporization of alcohol, such as the outside air temperature, fuel temperature, engine temperature, and cooling water temperature, is low, the startability is reduced due to the plug cover even if the reaching increase time to the upper limit concentration is shortened. Can be prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is an overall configuration diagram of an internal combustion engine and a control device for the internal combustion engine according to the first embodiment. The engine 1 is operated, for example, by burning various fuels in which ethanol and gasoline are mixed. An air cleaner 3 for purifying intake air is provided on the upstream side of the intake pipe 2 of the engine 1. The inflow amount of intake air is adjusted by a throttle valve 4 disposed inside the intake pipe 2. A three-way catalyst 8 is provided on the downstream side of the exhaust pipe 7 of the engine 1 to purify components such as HC, CO, and NOx in the exhaust gas. The injector 5 is connected to a control device, that is, an ECU (Electronic Control Unit) 10, and based on an injection control signal including an injection time from the ECU 10, various amounts of various fuels proportional to the injection time are put into the intake pipe 2. Spray.

  A throttle opening sensor (hereinafter referred to as TH sensor) 11 is connected to the throttle valve 4, measures the opening of the throttle valve 4, and inputs it to the ECU 10. An intake pipe absolute pressure sensor (hereinafter referred to as a PBA sensor) 12 measures an intake pipe absolute pressure (PBA) inside the intake pipe 2 and inputs the measured intake pipe absolute pressure to the ECU 10. An intake air temperature sensor (hereinafter referred to as a TA sensor) 16 measures the intake air temperature (TA) inside the intake pipe 2 and inputs the measured intake air temperature to the ECU. A water temperature sensor (hereinafter referred to as a TW sensor) 13 measures the cooling water temperature of the engine 1 and inputs the measured cooling water temperature (TW) to the ECU 10. A crank angle sensor (hereinafter referred to as a CRK sensor) 14 measures a crank angle (CRK) indicating a crank position of the engine 1 and inputs the measured crank angle to the ECU 10. The oxygen concentration sensor (hereinafter referred to as O2 sensor) 15 measures the oxygen concentration of the exhaust gas in the exhaust pipe 7 and inputs the measured oxygen concentration to the ECU 15.

FIG. 2 is a block diagram showing an internal configuration of the ECU 10. The ECU 10 includes a CPU (Central Processing Unit) 21, a RAM (Random Access Memory) 22, a ROM (Read Only Memory) 23, and an EEP-ROM (Electronically Erasable and Programmable Read Only Memory) 24. They are connected to each other by an internal bus.
The CPU 21 is connected to the TH sensor 11, the PBA sensor 12, the TA sensor 16, the TW sensor 13, the CRK sensor 14, and the O2 sensor 15 via an I / O (Input Output) bus, and measured by each sensor. Measurement information is input from each sensor. The CPU 21 is connected to the injector 5 via the I / O bus. By inputting an injection control signal to the injector 5, an amount of various fuels corresponding to the injection time included in the injection control signal is input to the injector 5. To spray.

  The RAM 22 is a storage device that is used as an operation area of a control program that operates in the CPU 21 and erases information stored therein when power supply is stopped. The ROM 23 stores in advance a control program that operates on the CPU 21 and control information for controlling the engine 1, such as a Pb / Ne map, a Ne / TH map, a correction coefficient table, and start control information. Even if the supply is stopped, the information is stored in the storage device without being erased. The EEP-ROM 24 is a storage device that stores information without being erased even if information is written and erased by the CPU 21 during operation of the CPU 21 and power supply is stopped.

(Principle of engine control)
Next, the principle of control of the engine 1 by the ECU 10 will be described. The engine 1 operates in a suitable state when the air-fuel ratio, which is the ratio between the air flowing in through the intake pipe 2 and the fuel injected from the injector 5, becomes an appropriate value. Here, the air-fuel ratio is represented by a value obtained by dividing the air amount by the fuel amount. The ECU 10 calculates an appropriate amount of injected fuel in order to operate the engine 1 in an optimal state under various conditions, and performs control to cause the injector 5 to inject the calculated amount of injected fuel. As a method of calculating the injected fuel amount by the ECU 10, different methods are employed at the time of starting the engine 1 and during normal operation due to the difference in the required injected fuel amount. The normal operation means a state in which the engine 1 is in a self-propelled operation regardless of a starter or the like.

(Calculation of injected fuel amount at start-up)
The start injection time (TICR) for injecting fuel into the injector 5 at the start is a value uniquely determined by the coolant temperature (TW) of the engine 1 if there is only one type of fuel. Specifically, a start injection table as shown in FIG. 3 showing the correspondence between the water temperature (TW) and the start injection time (TICR) in a graph is stored in advance in the ROM 23, and the start injection table is referred to at the time of start. The start injection time is obtained from the water temperature (TW) measured by the TW sensor 13, and the injector 5 is controlled to inject during the obtained start injection time. Note that the correspondence relationship between TW and TICR of the start injection table is calculated based on experimental results and the like in advance.

(Calculation of injected fuel during normal operation)
During normal operation, the intake air amount under various conditions is obtained by referring to a Pb / Ne map or Ne / TH map obtained in advance based on experimental results and the like. A basic fuel injection time (TIM) is calculated based on the determined target air-fuel ratio. FIG. 4A is a diagram showing an example of a Pb / Ne map, and FIG. 4B is a diagram showing an example of a Ne / TH map.

  The Pb / Ne map is a map used in an intake oxygen amount estimation method called a speed density method employed during low-load operation such as idling, and the intake pipe absolute pressure (PBA) and engine speed ( Ne) is obtained based on Ne). As shown in FIG. 4A, a certain correlation is not established between Pb and Ne, and the intake air amount is specified as an iso-air amount diagram.

  The Ne / TH map is a map used in an intake oxygen amount estimation method called a throttle speed method that is employed during high-load operation, and the engine rotation speed (Ne) and throttle opening (TH) are determined based on the map. The amount of intake air is determined based on the above. As shown in FIG. 4 (b), the Ne / TH map also does not have a certain correlation between Ne and TH, as in the Pb / Ne map, and the intake air amount is specified as an iso air amount diagram. Will be.

Once the basic fuel injection time (TIM) is calculated based on the intake air amount obtained from the Pb / Ne map or Ne / TH map, the correction based on the difference in environmental conditions between the experimental state and the actual operating state of the engine 1 is then performed. Need to do. FIG. 5 is a diagram showing an example of a correction coefficient table for obtaining an intake air temperature correction coefficient (KTA) corresponding to the intake air temperature (TA) obtained from the TA sensor 16 that measures the intake air temperature. As other correction coefficients, there are correction coefficients based on measured values obtained from the TH sensor 11, TW sensor 13, CRK sensor 14, and O2 sensor 15, and specifically, an increase correction coefficient after starting (KAST), There are correction coefficients such as a water temperature correction coefficient (KTW), an acceleration correction coefficient (TACC), an asynchronous correction coefficient (OPINJ), and an ignition timing coefficient.
A correction coefficient table exists for each of these correction coefficients, and a fuel injection time (Tout) for actually injecting fuel into the injector 5 is calculated based on the basic fuel injection time (TIM) and the plurality of correction coefficients. Is done.

(Engine control for various fuels)
As shown in Patent Document 1 described above, since ethanol contains oxygen atoms O in its composition, the amount of oxygen required for combustion per unit volume is less than that required when gasoline is burned. Therefore, when using a variety of fuels in which ethanol and gasoline are mixed, the stoichiometric air-fuel ratio is smaller than when using only gasoline fuel. Therefore, in order to operate the engine 1 in an optimum state, it is necessary to set a Pb / Ne map, a Ne / TH map, and various correction coefficient tables for each mixing ratio of ethanol and gasoline. By the way, even if the map or table for operating the engine 1 in an optimal state when ethanol is at a certain concentration is applied at another concentration within a certain range, the appropriate map or table at the other concentration is appropriate. It is known from experimental results that it is possible to perform the same level of control as in the case of providing Therefore, in the present embodiment, concentration ranges as shown in FIG. 6 are set, and ethanol 22% (E22), ethanol 50% (E50), and ethanol 80% (E80) are used as the reference concentrations of ethanol in the respective ranges. In addition, four types of ethanol 100% (E100) are determined in advance, and a Pb / Ne map, a Ne / TH map, and various correction coefficient tables are generated for each ethanol concentration. The reference concentration may be any number as long as it is three or more, and may be appropriately assigned to any concentration from 0% to 100%. Each map and table are set so as to have overlapping ranges as shown in FIG.

  As for the start injection time, even if the water temperature is constant (TW) as shown in FIG. 7 (a), the optimal injection time varies depending on the ethanol concentration. In addition, it is necessary to set an injection time that allows maximum injection when the ethanol concentration is at the upper limit while preventing excessive fuel injection when the ethanol concentration is at the lower limit. Therefore, also in the case of the starting injection time, a concentration range as shown in FIG. 7B is set, and ethanol 22% (E22), ethanol 50% (E50), ethanol 80% (E80), ethanol 100% Four start injection tables are stored in the ROM 23 in advance using (E100) as a reference concentration. Further, the start injection table includes a start injection time increase width Δti as a predetermined constant, the number N of repetitions indicating the number of times that the injection time is increased by the increase range when the injection is performed, The upper limit value Tmax of the injection time is associated. These constant values are also stored in the ROM 23 in advance. Hereinafter, the start injection table and information including these constants will be referred to as start injection information.

As shown in FIG. 8, the ROM 23 stores a Pb / Ne map, Ne / TH map, various correction coefficient tables, and start injection information generated for each ethanol reference concentration as a set of maps (hereinafter referred to as a reference fuel injection amount). As a map). The reference fuel injection amount map is called a map set. As a result, it is possible to control the engine 1 in all ethanol concentration ranges using four sets of reference fuel injection amount maps. Further, by using four sets of reference fuel injection amount maps, the ethanol content that can be continuously changed from 0% to 100% is represented by the reference concentration values of the four types of ethanol, so that the reference fuel having an appropriate reference concentration Since less correction from the injection amount map is required, the operation state can be stabilized.
It becomes. In the following description, the reference fuel injection amount map for each reference concentration is referred to as an E22% map, an E50% map, an E80% map, and an E100% map, respectively.

  Next, switching of the E22% map, E50% map, E80% map, and E100% map in the control program of the CPU 21 will be described. As shown in FIG. 9, the map switching by the control program of the CPU 21 is performed by the required injection amount magnification KO2 or KO2 calculated by the control program of the CPU 21 from the signal (VO2) indicating the oxygen concentration of the exhaust gas detected by the O2 sensor 15. This is done by referring to the average learning value (KO2REF). The required injection amount magnification KO2 indicates a large value when the concentration of oxygen in the exhaust gas is high, and indicates a small value when the concentration of oxygen in the exhaust gas is low. Therefore, when KO2 or KO2REF is a large value, it means that the fuel injection amount from the injector 5 is small (lean state), and further, the engine 1 is operated with a small fuel injection amount. Therefore, it is determined that the ethanol concentration is high, and processing for switching to a map having a high ethanol concentration is performed. On the other hand, when KO2 or KO2REF is a small value, it means that the fuel injection amount from the injector 5 is large (rich state), and further, the engine 1 is operated with a large fuel injection amount. Therefore, it is determined that the ethanol concentration is low, and processing for switching to a map with a low ethanol concentration is performed.

FIG. 10 is a flowchart showing the reference fuel injection amount map switching process by the control program of the CPU 21 during normal operation. The reference fuel injection amount map switching process according to the flowchart is repeatedly called and executed during the control process during normal operation.
First, the engine speed (Ne) is calculated based on the measured value obtained from the CRK sensor 14, and the calculated engine speed (Ne) and the throttle opening (TH) obtained from the TH sensor 11 are shown in FIG. It is determined whether it exists in the KO2REF calculation area shown in FIG. If it is outside the KO2REF calculation area, the process is terminated without switching the reference fuel injection amount map. If it is within the KO2REF calculation region, the coolant temperature (TW) and the intake air temperature (TA) are measured from the TW sensor 13 and the TA sensor 16, and the engine 1 is in a warm-up state, that is, in a normal operation state. It is determined whether or not there is (step Sa2). If it is determined that the warm-up state has not been reached, the process is terminated without switching the reference fuel injection amount map. If it is determined that the engine is warmed up, KO2REF is updated, that is, KO2REF is calculated based on the KO2 value obtained from the oxygen concentration newly measured by the O2 sensor 15 to calculate KO2REF. As a new KO2REF, Update is performed (step Sa3).

  Next, it is determined whether or not the updated KO2REF is within the threshold range of the current ethanol reference concentration (step Sa4). Here, the threshold values for the reference density are upper and lower threshold values set for each reference density shown in FIG. The threshold is adjusted and set so that the maps overlap. For example, as shown in FIG. 12, in the case of an E20% map, the lower limit threshold is 0 and the upper limit threshold is 1.1. In the case of the E50% map, the lower limit threshold is 0.85, and the upper limit threshold is 1.08. In the case of the E80% map, the lower limit threshold is 0.85, and the upper limit threshold is 1.1. In the case of the E100% map, only the lower limit threshold is set, and the value is 0.80. For example, if the current reference density is E50% and KO2REF is between 0.85 and 1.08, it is determined that the threshold value is within the range, and the map is not switched. On the other hand, when KO2REF is less than 0.85, switching to the E22% map is performed (step Sa5). When KO2REF is a value exceeding 1.08, switching to the E80% map is performed (step Sa5).

  When the map switching process shown in FIG. 10 is performed again after switching to the E80% map, since the map is switched to the E80 map, the oxygen concentration measured by the O2 sensor 15 changes, so KO2 also changes. . For example, when KO2REF is calculated as 1.0 by average learning based on KO2, the state is stable in the E80% map state.

  Since the map corresponding to the reference concentration of ethanol is selected by the reference fuel injection amount map switching processing described with reference to FIGS. 10 to 12 above, when the ethanol concentration changes during normal operation. Even if it exists, it becomes possible to drive the engine 1 in an optimal state. Further, since the change in the ethanol concentration is detected based on the oxygen concentration detected from the O2 sensor 15, it is not necessary to provide an ethanol concentration sensor in the fuel tank, and the cost can be reduced. .

  In the reference fuel injection amount map switching process described with reference to FIG. 10, the process based on KO2REF is described. However, KO2 calculated based on the oxygen concentration measured by the O2 sensor 15 is used instead of KO2REF. 10 may be applied to the above.

  Next, referring to FIG. 13 and FIG. 14, when the ethanol concentration during operation is detected during normal operation and the operation is performed again after the engine 1 is stopped, the ethanol detected during operation is detected. Start control for starting the engine with reference to the concentration will be described.

  In FIG. 13, first, during normal operation, the control program of the CPU 21 calculates the ethanol concentration from the oxygen concentration measured by the O2 sensor 15, performs average learning on the calculated ethanol concentration, and calculates the ethanol concentration learning value. (Step Sb1).

  Next, the reference fuel injection amount map described above is used as a setting set in which the reference concentration is obtained from the ethanol concentration range shown in FIG. 6 and the calculated ethanol concentration learning value and stored in the EEP-ROM 24 from the obtained reference concentration. One of an E22% map, an E50% map, an E80% map, and an E100% map is selected (step Sb2). Then, the selected setting set and reference density are stored in the EEP-ROM 24 (step Sb3). Thereafter, the main SW (switch) is turned off, and the power supply from the battery to the ECU 10 is stopped (step Sb4). At this time, the information stored in the RAM 22 is deleted, but the information stored in the ROM 23 and the information stored in the EEP-ROM 24 are retained.

  Next, when the main SW is turned on, power supply from the battery to the ECU 10 is started, and the control program of the CPU 21 is activated, the control program reads the setting set from the EEP-ROM 24 (step Sb5). The control program reads the start injection information from the read setting set, and starts based on the start injection table included in the read start injection information and the coolant temperature of the engine 1 measured by the TW sensor 13. TICR, which is the initial value of the injection time, is obtained. Further, the increase width Δti, the number of repetitions N, and the start injection time upper limit value Tmax included in the start injection information are read from the start injection information and set in the control program. At this time, the variable of the starting injection number n is reset to 0 (step Sb6).

Next, the control program determines whether or not cranking is being performed (step Sb7). If cranking is not being performed, the determination is continued until cranking is started. If it is determined that cranking is being performed, a value obtained by adding 1 to the current start injection number n is substituted for the start injection number n. In the first time, 1 is substituted into the number of start injections n (step Sb8).
Next, the control program determines whether or not the start injection time TICR is less than the start injection time upper limit value Tmax (step Sb9). When the start injection time TICR is less than the start injection time upper limit value Tmax (step Sb9: Yes), the control program then determines whether the start injection number n is equal to the repetition number N (step Sb10). When the control program determines that the start injection number n is equal to the repetition number N (step Sb10: Yes), the value obtained by adding the increase width Δti to the current TICR is substituted for TICR (step Sb11), and the start injection number n Is reset to 0 (step Sb12). Next, the control program is based on whether or not the current engine speed (Ne) calculated based on the measured value of the CRK sensor 14 exceeds a threshold value (A) indicating the speed that serves as a reference for starting determination. It is then determined whether or not the start has been completed (step Sb13). When the control program determines that the current engine speed (Ne) exceeds the threshold (A) and the start has been completed (step Sb13: Yes), the normal operation is started, so the injection control is performed. While performing injection control during normal operation, that is, the processing shown in FIG. 10 (step Sb14), the processing from step Sb1 to step Sb3 is repeated until the main SW is turned off. On the other hand, when the current engine speed (Ne) is equal to or less than the threshold (A) and it is determined that the engine is being started (step Sb13: No), the process returns to step Sb7 to continue the start control. In Step Sb9, when it is determined that the start injection time TICR is not less than the injection time upper limit value Tmax, that is, when the start injection time TICR is equal to or greater than Tmax (Step Sb9: No), the start injection number n is repeated. If it is determined that the number of times N is not equal, that is, if the number of start injections n has not reached the number of repetitions (step Sb10: No), the completion of start in step Sb13 is determined while maintaining the current start injection time TICR. Do.

  FIG. 14 is a diagram showing a change in the start injection time TICR when the number of repetitions N is set to 4 in the process of FIG. 13, and every time four injections are performed, TICR increases step by step by Δti, and cumulative start When the injection time reaches Tmax, cranking is continued with TICR maintained. At this time, the minimum value at which TICR changes is the minimum required injection amount (lower limit concentration required injection amount) at the reference ethanol concentration set in the setting set, and the maximum value is the maximum required injection at the ethanol concentration. Δti and the number of repetitions N are determined in advance so that the amount (the upper limit concentration required injection amount) is reached.

  Even if ethanol or gasoline is replenished at the time of stop by the processing of FIG. 13, the main SW is stopped because the mixing ratio of the fuel remaining in the fuel pipe is the state before replenishment. By performing start control using the reference fuel injection amount map corresponding to the reference concentration of ethanol at the time of the previous normal operation, quick start control in an appropriate state while avoiding plug fogging in the engine 1 is performed. It becomes possible. Further, in the process of FIG. 13, every time the number of start injections n reaches the number of repetitions N, the TICR is increased by the amount of increase Δti, so that the fuel injection time is reduced until the start of the engine 1 is completed. The starting control can be performed by gradually increasing, that is, by gradually increasing the fuel injection amount injected from the injector 5.

  In the process of FIG. 13, it is described that any one of the E22% map, E50% map, E80% map, and E100% map is stored in the EEP-ROM 24. However, only the ethanol concentration learning value or the reference concentration is stored in the EEP-ROM. You may make it memorize | store in ROM24 and read the reference fuel injection amount map corresponding from ROM23 based on the value read from EEP-ROM24 at the next starting.

  Further, in the process of FIG. 13, every time the start injection number n reaches the repetition number N, the TICR is increased by the increase width Δti, but the present invention is not limited to this embodiment, and the injection is performed. The TICR may be increased by the increase amount Δti every time the performed time exceeds a certain time.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the start control of the engine 1, in the first embodiment, the ethanol concentration detected during operation is detected in the normal operation, and the ethanol detected during operation when the operation is performed again after the engine 1 is stopped. Start control is performed to start the engine with reference to the concentration. On the other hand, in the second embodiment, the reference concentration of ethanol is the minimum, that is, the reference fuel injection amount map is switched in order from the E22% map to perform the start control. In the second embodiment, in the start control information, the increase width Δti of the start injection time for each ethanol concentration, the number of repetitions N, and the upper limit value Tmax for the start injection time correspond to the reference fuel injection amount map for each reference concentration. It is assumed that they are attached and stored in advance.

  FIG. 15 is a flowchart showing a processing procedure of start control according to the second embodiment. First, when the main SW is turned on, power supply from the battery to the ECU 10 is started, and the control program of the CPU 21 is activated, the control program sets a minimum reference concentration, that is, an ethanol reference concentration of 22% in the variable E. (Step Sc1). Here, setting the ethanol concentration of 22% means that the start injection time input to the injector 5 is set as the shortest time as shown in FIG. 7 (a), that is, ethanol injected from the injector 5 and The fuel injection amount of the mixed fuel of gasoline is set to the minimum state. Next, the control program reads the reference fuel injection amount map from the ROM 23 according to the set reference concentration value. First, the E22% map is read (step Sc2). Next, the control program reads the start control information from the E22% map, and the start injection time based on the start injection table included in the read start injection information and the coolant temperature of the engine 1 measured by the TW sensor 13. TICR, which is the initial value of, is obtained. Further, the increase width Δti, the number of repetitions N, and the starting injection time upper limit value Tmax associated with the E22% map are read out and set in the control program. At this time, the variable of the starting injection number n is reset to 0 (step Sc3).

  Next, the control program of the CPU 21 determines whether or not cranking is in progress (step Sc4). If cranking is not being performed, the determination is continued until cranking is started. If it is determined that cranking is being performed, a value obtained by adding 1 to the current start injection number n is substituted for the start injection number n. In the first time, 1 is substituted for the number of start injections n (step Sc5). Next, the control program determines whether or not the start injection time TICR is less than the start injection time upper limit value Tmax (step Sc6). If the start injection time TICR is less than the start injection time upper limit value Tmax (step Sc6: Yes), the control program then determines whether the start injection number n is equal to the number of repetitions N (step Sc7). When the control program determines that the starting injection number n is equal to the repetition number N (step Sc7: Yes), the value obtained by adding the increase width Δti to the current TICR is substituted into TICR (step Sc8), and the starting injection number n Is reset to 0 (step Sc9). Next, the control program is based on whether or not the current engine speed (Ne) calculated based on the measured value of the CRK sensor 14 exceeds a threshold value (A) indicating the speed that serves as a reference for starting determination. It is then determined whether or not the start has been completed (step Sc10). When the control program determines that the current engine speed (Ne) exceeds the threshold value (A) and the start is completed (step Sc10: Yes), the normal operation is started, so the injection control is performed. The injection control during normal operation, that is, the processing shown in FIG. 10 is performed (step Sc11). On the other hand, when it is determined that the current engine speed (Ne) is equal to or less than the threshold value (A) and the engine is being started (step Sc10: No), the process returns to step Sc4 to continue the start control. Further, when it is determined that the start injection number n is not equal to the repetition number N, that is, when the start injection number n has not reached the repetition number (step Sc7: No), the current start injection time TICR is maintained, In step Sc10, the start completion is determined.

  On the other hand, if it is determined in step Sc6 that the start injection time TICR is not less than the start injection time upper limit value Tmax, that is, if the start injection time TICR is equal to or greater than Tmax (step Sc6: No), the control program changes the variable E , It is determined whether or not the next reference density exists (step Sc12). When the next reference concentration does not exist, that is, when the current reference concentration is 100% ethanol, the reference fuel injection amount map does not exist any more, so the E100% map is maintained and the start completion determination process in step Sc10 is performed. move on. On the other hand, when it is determined that the next reference concentration exists with reference to the variable E (step Sc12: Yes), the next reference concentration is set to the variable E (step Sc13), and the engine 1 starts the processing after step Sc2. Repeat until

  By the processing of the second embodiment, the start control can be performed by switching from the reference fuel injection amount map having the smallest reference concentration of ethanol to the reference fuel injection amount map having the higher reference concentration in order. By switching the reference fuel injection amount map, the fuel injection time is switched from a state where the fuel injection time is short until the start of the engine 1 is completed to a state where a longer fuel injection time is set according to the starting situation. This means that starting control is started from the state where the fuel injection amount of the mixed fuel of ethanol and gasoline is the smallest, and the state is switched to a state where the fuel injection amount is larger depending on the starting state until the starting of the engine 1 is completed. The start control can be performed. As a result, it is possible to perform start control in an appropriate state while avoiding plug fogging in the engine 1.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the third embodiment, the engine start control is performed so that the increase width of the start injection time is not constant and the increase width is gradually increased. By performing the control of gradually increasing the amount of increase in the starting injection time, the amount of increase in the fuel injection amount is gradually increased accordingly. The best mode for performing such start control is a mode in which the start injection time is exponentially increased.

  FIG. 16 is a graph showing a temporal change in the start injection time TICR in the present embodiment. In this figure, the horizontal axis is the time from when the main switch is turned “ON” and cranking is started, and the unit is seconds (sec). The vertical axis represents the start injection time TICR, and the unit is milliseconds (msec). In this figure, the cooling water temperature (TW) measured by the TW sensor 13 is minus 10 degrees Celsius, zero degrees Celsius, 10 degrees Celsius, 15 degrees Celsius, 25 degrees Celsius, 40 degrees Celsius, and 89 degrees Celsius, respectively. Shows the regrettable change in the starting injection time TICR. As shown in the figure, the start injection time TICR increases with the passage of time regardless of the coolant temperature TW. Further, in any case of the coolant temperature TW, the amount of increase in the start injection time TICR (the difference in the start injection time TICR between adjacent plot points) increases with the passage of time. Further, as will be described later, in this figure, control is performed such that the starting injection time increases exponentially. In the control method of the present embodiment, the upper limit Tmax of the start injection time is set (however, Tmax is outside the range of the graph shown in the figure).

In the present embodiment, the start injection time TICR is expressed by the following equation. That is,
TICR = TICRm−Δbase + Δbase × AF ⁽ⁿ⁻¹⁾
It is. Here, TICRm is the initial start injection time, Δbase is the injection time coefficient, AF is the increase coefficient, and n is the number of increases (initially n = 1). Regarding the initial start injection time TICRm, the injection time coefficient Δbase, and the increase coefficient AF, set values for each cooling water temperature (TW) are set and stored in the ROM 23. The increase coefficient AF is set to an appropriate value larger than 1. And the increase ΔTICR of the injection time from the previous time is obtained from the above equation,
ΔTICR
= Δbase × (AF ⁽ⁿ⁻¹⁾ −AF ⁽ⁿ⁻²⁾ )
= Δbase × AF ⁽ⁿ⁻²⁾ × (AF−1)
It is. That is, the increase width of the injection time and the increase width of the fuel injection amount are gradually increased. In addition, these increases are increasing exponentially. That is, in the present embodiment, the start control is performed so that the increment of the fuel injection amount at every predetermined time or every predetermined number of times to gradually increase the fuel injection amount increases and changes exponentially (following the exponential function). Yes. By using such an increase ΔTICR, there is also an advantage that the control procedure can be simplified.

FIG. 17 is a flowchart showing a processing procedure of start control according to the present embodiment. First, when the main SW is turned on, power supply from the battery to the ECU 10 is started, and the control program of the CPU 21 is activated, the processing procedure of this flowchart is started.
The control program reads a reference fuel injection amount map from the ROM 23 according to the set reference concentration value (step Sd1).

  Next, the control program sets start injection information based on the value included in the read reference fuel injection amount map and the coolant temperature of the engine 1 measured by the TW sensor 13 (step Sd2). Here, the initial start injection time TICRm, the start injection time upper limit value Tmax, the injection time coefficient Δbase, and the increase coefficient AF are set as start injection information. In the following, the initial value of the variable α used for calculating the starting injection time TICR is set to Δbase (step Sd3).

Next, the control program determines whether or not cranking is being performed (step Sd4). If cranking is not in progress, the process returns to step Sd4, and the determination is continued until cranking is started. If it is determined that cranking is in progress, the process proceeds to the next step Sd5.
Next, the control program calculates the start injection time TICR using the initial start injection time TICRm, the injection time coefficient ΔBASE, and the value of the variable α (step Sd5). Here, it is assumed that TICR = TICRm−Δbase + α. In the process of the first step Sd5 of the loop in this flowchart, since the value of the variable α is Δbase, TICR = TICRm.

Next, the control program determines whether or not the calculated start injection time TICR is less than the start injection time upper limit value Tmax (step Sd6). When the start injection time TICR is less than the start injection time upper limit value Tmax (step Sd6: YES), the value of α × AF is substituted into the variable α using the value of the increase coefficient AF (step Sd7), and otherwise In the case of (Step Sd6: NO), the process proceeds directly to Step Sd8.
Next, the control program is based on whether or not the current engine speed (Ne) calculated based on the measured value of the CRK sensor 14 exceeds a threshold value (A) indicating the speed that serves as a reference for starting determination. It is then determined whether or not startup has been completed (step Sd8). When the control program determines that the current engine speed (Ne) exceeds the threshold (A) and the start is complete (step Sd8: Yes), the normal operation is started, so the injection control is performed. The injection control during normal operation, that is, the processing shown in FIG. 10 is performed (step Sd9). On the other hand, if the current engine speed (Ne) is equal to or less than the threshold (A) and it is determined that the engine is being started (step Sd8: No), the process returns to step Sd4 to continue the start control.

  When the control is performed such that the increment of the starting injection amount is constant every one time or every N times (repetition times), in order to increase a large amount within a short time, the one time increment is increased. There is a need. However, in the case of a fuel composition with a small injection amount requirement, there is a possibility that the fuel will be excessive with one increase and the plug may be fogged. In other words, a trade-off between increasing the increase over a short period of time to reduce plug fogging and increasing the increase over a short period of time, or increasing the increment to increase plugging in a short period of time. Are in a relationship.

However, according to the control method of the present embodiment, a large amount can be increased in a short time while preventing the plug from being fogged, and a smooth engine start can be realized. In other words, as explained with reference to the figure above, by gradually increasing the starting injection amount increment for each injection, the starting injection amount increase is not linear but exponential. It becomes. The starting injection amount is controlled by appropriately setting two parameters, an injection time coefficient Δbase and an increase coefficient AF. Then, these parameters are set so that the initial increment after the engine SW is turned on becomes smaller and the later increment becomes larger. Thereby, the initial stage in which the fuel injection amount is gradually increased (the initial period is, for example, a relatively left region in the graph of FIG. 16, for example, a region from 0.0 second to 2.0 seconds on the horizontal axis of the graph). ) For a predetermined time (the predetermined time is, for example, a predetermined width of the horizontal axis in the graph of FIG. 16) or a predetermined number of times (the predetermined number of times is, for example, the start injection time TICR in the horizontal axis direction of the graph of FIG. 16) The latter period (later period) in which the fuel injection amount is gradually increased rather than the increment of the fuel injection amount for each calculation count (for example, the relatively right region in the graph of FIG. 16). The starting control is performed so that the increment of the fuel injection amount increases every predetermined time or every predetermined number of times (region larger than 2.0 seconds). In this way, in order to make the later increment larger than the initial increment, for example, unless the fuel injection amount reaches the upper limit value, control is performed so that the increment is larger than the previous increment every time.
For this purpose, in addition to using an exponential function, for example,
TICR = TICRm + Δbase × (n−1) ² , or TICR = TICRm + Δbase × (n−1) ³ , or TICR = TICRm + Δbase × (n−1) ⁴
For example, a power function of n times may be used.
As a result, a large increase can be obtained in a short time while preventing plug fogging, and a reliable engine start can be performed.

  In this embodiment, the start injection information is set according to the coolant temperature (step Sd2 in FIG. 17), but as a modification, the water temperature, the engine oil temperature, the intake air temperature, the atmospheric pressure, the fuel Means for measuring temperature, fuel composition, and the like may be provided, and control may be performed so that the increment of the injection amount gradually increases based on one or more of these measurement results. Further, the upper limit of the required injection amount is set based on one or more kinds of measurement results such as the water temperature, the engine oil temperature, the intake air temperature, the atmospheric pressure, the fuel temperature, and the fuel composition.

  In the present embodiment, the reference injection amount map that does not depend on the fuel mixture ratio is used. Thus, even if the reference injection amount map does not depend on the fuel mixture ratio, the engine can be started in a relatively short time because the above-described control gradually increases the injection amount. . Of course, as performed in the above-described embodiment, a plurality of reference fuel injection amount maps corresponding to the mixed concentration of various fuels may be stored and appropriately selected and used. Further, it is memorized which map is used from among a plurality of reference fuel injection amount maps, and based on the storage, the reference fuel injection amount map used immediately before the previous stop is used at the start of the start. It may be.

  According to the third embodiment, good startability can be ensured while reducing the time required for engine start, regardless of the change in the fuel mixture ratio. In addition, the plug can be prevented from being fogged. In addition, by setting parameters, it is possible to easily set an injection amount increase pattern that meets the requirements.

  The Pb / Ne map described above is described as information indicating the relationship between PBA, Ne, and the intake air amount. However, the basic fuel injection time (TIM) is calculated based on the intake air amount and the target air-fuel ratio, You may make it comprise as a three-dimensional map which showed the relationship between the calculated basic fuel injection time (TIM), PBA, and Ne. Similarly, the Ne / TH map may be configured as a three-dimensional map showing the basic fuel injection time (TIM) and the relationship between Ne and Th.

  In the above embodiment, the control process is performed based on the coolant temperature (TW) of the engine 1, but instead of the coolant temperature, the oil temperature of the engine oil of the engine 1, the cylinder, The correction may be performed based on the output of the head temperature sensor or the like.

  In addition, the entire function of the ECU 10 in the above-described embodiment or a part of the function is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system. It may be realized by executing. Here, the “computer system” includes an OS and hardware such as peripheral devices.

  The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. It is also possible to include those that hold a program for a certain time, such as a volatile memory inside a computer system serving as a server or client in that case. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

1 is an overall configuration diagram of an internal combustion engine and a control device for an internal combustion engine according to a first embodiment of the present invention. It is the figure which showed the internal structure of ECU by 1st Embodiment of this invention, and the connection relationship with a sensor and an injector. It is the figure which showed the starting injection table by 1st Embodiment of this invention. It is the figure which showed the Pb / Ne map and Ne / TH map by 1st Embodiment of this invention. It is the figure which showed the correction coefficient table for calculating | requiring the intake air temperature correction coefficient by 1st Embodiment of this invention. It is the figure which showed the ethanol concentration range by 1st Embodiment of this invention. It is the figure which showed the density | concentration range of the ethanol in the starting injection table by 1st Embodiment of this invention, and starting control. It is the figure which showed the reference | standard fuel injection amount map by 1st Embodiment of this invention. It is a conceptual diagram of the switching process of the reference | standard fuel injection amount map by 1st Embodiment of this invention. It is the flowchart which showed the map switching process at the time of normal driving | operation by 1st Embodiment of this invention. It is the figure which showed the KO2REF calculation area | region referred in the map switching process at the time of normal driving | operation by 1st Embodiment of this invention. It is the figure which showed the threshold value of KO2REF referred in the map switching process at the time of normal driving | operation by 1st Embodiment of this invention. It is the flowchart which showed the process of the start control by 1st Embodiment of this invention. It is the flowchart which showed the change of TICR by the process of start control by 1st Embodiment of this invention. It is the flowchart which showed the process of the start control by 2nd Embodiment of this invention. It is the graph which showed the time change of the starting injection time TICR by 3rd Embodiment of this invention. It is the flowchart which showed the process sequence of the start control by 3rd Embodiment of this invention.

Explanation of symbols

  1 Engine (Internal Combustion Engine) 10 ECU (Fuel Injection Control Device) 15 O2 Sensor (Oxygen Concentration Sensor) Steps Sb13, Sc10, Sd8 Start Completion Detection Unit

Claims (9)

A fuel for an internal combustion engine for multi-fuel, having start completion detection means for detecting a start state of the internal combustion engine, and determining a fuel injection amount according to the state of the internal combustion engine after the start completion detection is detected by the start completion detection means; In the injection control device,
Remember the reference fuel injection amount map,
Start control of the internal combustion engine using the reference fuel injection amount map, and start control of the internal combustion engine by gradually increasing the fuel injection amount until the start of the internal combustion engine is completed.
A fuel injection control device for an internal combustion engine for multiple fuels. A plurality of reference fuel injection amount maps corresponding to the mixed concentrations of various fuels are stored,
Storing which of the plurality of reference fuel injection amount maps is used;
Based on the memory, the start control of the internal combustion engine is performed using the reference fuel injection amount map used immediately before the previous stop when starting.
The fuel injection control device according to claim 1. 3. The fuel injection amount is increased when the fuel injection amount is not completed even though the fuel is injected a predetermined number of times in the reference fuel injection amount map used at the start of cranking and cranking is performed. Fuel injection control device. 3. The fuel injection amount is increased when the fuel injection amount is not completed even though the fuel is injected for a predetermined time and cranked in the reference fuel injection amount map used at the start of the start. 4. Fuel injection control device. The fuel injection control device according to claim 2, wherein the reference fuel injection amount map includes three or more types of Pb / Ne maps corresponding to a mixing ratio of ethanol and gasoline. An oxygen concentration sensor that generates an output corresponding to the oxygen concentration in the exhaust gas is provided in the exhaust system of the internal combustion engine,
The fuel injection control device according to claim 2, wherein an ethanol mixing ratio in the fuel is estimated based on an output of the oxygen concentration sensor. A fuel for an internal combustion engine for multi-fuel, having start completion detection means for detecting a start state of the internal combustion engine, and determining a fuel injection amount according to the state of the internal combustion engine after the start completion detection is detected by the start completion detection means; In the injection control device,
A plurality of reference fuel injection amount maps corresponding to the mixed concentrations of various fuels are stored,
At the start of start, the reference fuel injection amount map with the smallest fuel injection amount is used to start control of the internal combustion engine, and the reference fuel injection amount having a larger fuel injection amount depending on the start situation until the start of the internal combustion engine is completed Switch to the map and perform start control,
A fuel injection control device for an internal combustion engine for multiple fuels. Fuel injection every predetermined time or every predetermined number of times when the fuel injection amount is gradually increased rather than the increment of the fuel injection amount every predetermined time or every predetermined number when gradually increasing the fuel injection amount Start control so that the increment of quantity becomes large,
The fuel injection control device according to claim 1. Start control is performed so that the increment of the fuel injection amount at every predetermined time or every predetermined number of times when the fuel injection amount is gradually increased increases exponentially.
The fuel injection control device according to claim 8.

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