JP2010007630A - Fuel injection control device and fuel injection control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device capable of inhibiting the fluctuation of a combustion state occurring accompanied by the purge of evaporated gas for an internal combustion engine making a plurality of kinds of fuel having different properties changed over and injected. <P>SOLUTION: This device is applied to an engine 1 which makes gasoline (first fuel) and hydrogen fuel (second fuel) changed over and injected, and is provided with a canister 40 (evaporated gas treatment device) adsorbing the fuel vapor (evaporated gas) of gasoline and purging it to an intake air passage 2a. The device is provided with second injection quantity calculation means S305, S306-S316 calculating target injection quantities (second injection quantities) of hydrogen fuel based on an engine load state, and a second control means (ECU30) controlling the operation of a hydrogen injector 21 based on a target injection quantity of hydrogen fuel. The second injection quantity calculation means S306-S316 in the execution of purge calculate target injection quantities of hydrogen fuel based on quantities of purged fuel vapor and the target air-fuel ratio (properties) of both the fuel in addition to engine load state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection control device and a fuel injection control system applied to an internal combustion engine that switches and injects a liquid first fuel for combustion and a second fuel having different properties from the first fuel.

  Conventionally, in Patent Document 1 and the like, an internal combustion engine in which a second fuel (for example, hydrogen gas) is stored in a tank separately from a first fuel (for example, gasoline) to be used for combustion, and both the fuels are switched and injected. It is disclosed.

In addition, since hydrogen gas is stored in a tank in a gas state while gasoline is stored in a liquid state, there is a concern that the stored gasoline evaporates and is released into the atmosphere. For such concerns, Patent Document 2 and the like disclose an evaporative gas processing apparatus that adsorbs an evaporative gas of gasoline and purges it into an intake passage.
JP 2001-193511 A JP 2003-148258 A

  However, in the case where the evaporative gas treatment device is mounted on the internal combustion engine that switches and injects both fuels as described above, if the gasoline evaporative gas is purged during the hydrogen gas injection, the gasoline evaporative gas and the hydrogen gas having different properties are mixed. The present inventors have found that there is a problem that the combustion state fluctuates greatly due to simultaneous combustion.

  The present invention has been made to solve the above-mentioned problems, and its object is to apply to an internal combustion engine that switches and injects a plurality of fuels having different properties, and changes in combustion states caused by evaporative gas purging. An object of the present invention is to provide a fuel injection control device and a fuel injection control system that suppress the above.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

In invention of Claim 1,
An internal combustion engine for switching and injecting a liquid first fuel to be used for combustion and a second fuel having different properties from the first fuel, wherein the first fuel evaporative gas is adsorbed and purged into an intake passage In a fuel injection control device applied to an internal combustion engine equipped with a gas processing device,
A second injection amount calculating means for calculating a second injection amount which is an injection amount of the second fuel based on at least a load state of the internal combustion engine; and a second injector for injecting the second fuel based on the second injection amount. Second control means for controlling the operation of
In addition to the load state, the second injection amount calculation means when performing the purge includes a purge amount of purged evaporation gas (hereinafter referred to as purge evaporation gas), the properties of the first fuel, and the first The second injection amount is calculated based on the properties of two fuels.

  According to this, compared with the case where the second injection amount is simply calculated based on the purge amount, the second injection amount is calculated based on the properties of both fuels in addition to the purge amount. Even when both fuels having different properties are combusted simultaneously by purging the fuel evaporative gas, it is possible to easily calculate the second injection amount so as to suppress fluctuations in the combustion state. Therefore, according to the present invention that controls the operation of the second injector based on the second injection amount calculated in this way, it is possible to easily suppress fluctuations in the combustion state caused by the purge of the evaporated gas.

In invention of Claim 2,
Means for calculating a purge evaporation gas use air amount, which is an air amount used when the purge evaporation gas burns at the target air-fuel ratio;
Means for subtracting the purge evaporative gas use air amount from a total intake air amount flowing into the combustion chamber from the intake passage to calculate a second fuel use air amount that is an air amount supplied to the second fuel; ,
Means for calculating, as the second injection amount, an injection amount of the second fuel necessary for the second fuel use air amount when the second fuel burns at the target air-fuel ratio;
It is characterized by having.

  According to this, since the purge evaporation gas use air amount is calculated based on the target air-fuel ratio (property) of the purge evaporation gas, the second fuel use air amount is obtained by subtracting the purge evaporation gas use air amount from the total intake air amount. It can be calculated accurately. Then, the injection amount of the second fuel necessary for the second fuel use air amount accurately calculated in this way is calculated based on the target air-fuel ratio (property) of the second fuel. The second injection amount that can be suppressed can be calculated with high accuracy. A specific example of each target air-fuel ratio is a theoretical air-fuel ratio.

  According to a third aspect of the present invention, the amount of air flowing in from the upstream side of the portion where the purge is performed in the intake passage and the amount of mixed air mixed into the intake passage together with the purge evaporated gas are added. Then, the total intake air amount is calculated.

  According to this, the total intake air amount used for calculating the second injection amount is calculated in consideration of the amount of mixed air mixed into the intake passage together with the purge evaporated gas, so that the total intake air amount can be accurately calculated. As a result, the calculation accuracy of the second injection amount can be further improved.

  The invention according to claim 4 is characterized in that the second control means performs open-loop control of the operation of the second injector based on the second injection amount calculated by the second injection amount calculation means.

  According to this, since the operation of the second injector is open-loop controlled based on the purge amount and the second injection amount calculated based on the properties of both fuels, the operation of the second injector is feedback-controlled based on the oxygen concentration in the exhaust gas. Compared to the case, the injection amount of the second fuel can be changed immediately as the purge starts. Therefore, even when the evaporative gas processing apparatus operates to purge the adsorbed evaporative gas at once in a short time, the response is made so that the injection amount of the second fuel is immediately changed according to the execution of the purge. Enough to secure.

  In addition to the means for performing the open loop control, a means for feedback controlling the operation of the second injector based on the oxygen concentration in the exhaust gas may be provided.

  In a fifth aspect of the present invention, there is a remaining determination means for determining whether or not a tank storage amount of the first fuel remains over a predetermined amount, and a first injection state in which the first fuel is injected from the first injector; Switching control means for switching between a second injection state in which the second fuel is injected from the second injector, and when the remaining determination means determines that a predetermined amount or more remains, the purge is performed. When executed, the switching control means switches to the first injection state.

  According to this, when the first fuel remains in a predetermined amount or more, the purge is switched to the first injection state when the purge is executed, so that it is possible to avoid a situation where both fuels having different properties are burned simultaneously. If the purge evaporative gas and the injected fuel are the same fuel (that is, the first fuel), it is possible to calculate the injection amount of the first fuel so as to suppress the fluctuation of the combustion state caused by the purge of the evaporative gas. Can be realized easily. Therefore, it is possible to easily suppress fluctuations in the combustion state caused by purging. In addition, in this case, the calculation by the second injection amount calculator such as calculating the second injection amount based on the purge amount and the properties of the two fuels can be eliminated, so that the calculation processing load can be reduced.

  If the first fuel does not remain over a predetermined amount, the second injector cannot be switched to the first injection state, but the second injector is operated based on the second injection amount calculated by the second injection amount calculation means. Since it controls, the fluctuation | variation of a combustion state can be suppressed as mentioned above.

In invention of Claim 6,
An internal combustion engine for switching and injecting a liquid first fuel to be used for combustion and a second fuel having different properties from the liquid fuel, wherein the evaporated gas adsorbs the evaporated gas of the first fuel and purges it into the intake passage In a fuel injection control device applied to an internal combustion engine provided with a processing device,
And a switching control unit that switches between a first injection state in which the first fuel is injected from the first injector and a second injection state in which the second fuel is injected from the second injector, and the switching control unit executes the purge When performing, it switches to the said 1st injection state, It is characterized by the above-mentioned.

  According to this, since it switches to the 1st injection state at the time of purge execution, the situation where both fuels with different properties are burned simultaneously can be avoided. If the purge evaporative gas and the injected fuel are the same fuel (that is, the first fuel), it is possible to calculate the injection amount of the first fuel so as to suppress the fluctuation of the combustion state caused by the purge of the evaporative gas. Can be realized easily. Therefore, it is possible to easily suppress fluctuations in the combustion state caused by purging.

  According to a seventh aspect of the present invention, there is provided an operation switch that is operated by a driver of the internal combustion engine and outputs a command signal that instructs the switching control means to switch between the first injection state and the second injection state. The switching control means forcibly switches to the first injection state regardless of the command content by the command signal when the purge is executed.

  According to this, it is possible to avoid the situation in which both fuels having different properties are burned at the same time regardless of the operation contents by the driver, and thus the above-described combustion state fluctuation suppressing effect can be suitably exhibited. In carrying out the invention described in claim 6 or claim 6, contrary to the invention described in claim 7, the two injection states are given priority to the operation content of the driver over the switching control by the switching control means. You may make it switch.

  The invention according to claim 8 includes the fuel injection control device, at least one of a first injector that injects a first fuel, a second injector that injects the second fuel, and the evaporative gas treatment device. A fuel injection control system characterized by the above. According to this fuel injection control system, the above-described various effects can be similarly exhibited.

  Hereinafter, embodiments in which a fuel injection control device according to the present invention is applied to an internal combustion engine that functions as a travel drive source mounted on a vehicle will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the same reference numerals is used.

(First embodiment)
FIG. 1 is a diagram mainly showing a fuel supply system of an engine 1 (internal combustion engine). The engine 1 performs injection by switching between liquid fuel (first fuel) and gaseous fuel (second fuel) for combustion. It has a function to make it. In this embodiment, gasoline is adopted as the liquid fuel, and hydrogen is adopted as the gaseous fuel. A vehicle equipped with the engine 1 is equipped with a gasoline tank 10 for storing gasoline in a liquid state and a hydrogen tank 20 for storing hydrogen in a compressed gas state.

  The gasoline stored in the gasoline tank 10 is boosted by a pump (not shown) and supplied to the gasoline injector 11 (first injector). The gasoline injector 11 is configured to open and close a nozzle hole for injecting gasoline by a needle valve (not shown), and by controlling the opening and closing operation of the needle valve by an electronic control unit (hereinafter referred to as ECU 30). Control of gasoline injection and injection stop. The hydrogen stored in the hydrogen tank 20 is supplied to a hydrogen injector 21 (second injector), and the ECU 30 controls the injection and stoppage of hydrogen in the same manner as the gasoline injector 11.

  The hydrogen injector 21 is arranged to inject gasoline directly into the combustion chamber 1 a of the engine 1. On the other hand, the gasoline injector 11 is attached to an intake pipe 2 that introduces intake air into the combustion chamber 1a, and is arranged to inject gasoline into the intake passage 2a inside the intake pipe 2.

  Evaporated gas (hereinafter referred to as fuel vapor) evaporated in the gasoline tank 10 is processed by the canister 40 (evaporated gas processing device) so as not to be released into the atmosphere. The canister 40 includes an adsorbent 41 (for example, activated carbon) that adsorbs fuel vapor, and a case 42 that accommodates the adsorbent 41 therein.

  The case 42 includes a vapor introduction pipe 43 that communicates with the gasoline tank 10 and introduces fuel vapor in the gasoline tank 10 into the case 42, an air introduction pipe 44 that introduces air into the case 42, and a canister 40. A purge pipe 45 for introducing and purging the adsorbed fuel vapor into the intake pipe 2 is provided. A purge control valve 46 for opening and closing the purge passage 45a is attached to the purge pipe 45. The opening / closing operation of the purge control valve 46 is controlled by the ECU 30 (duty control in this embodiment).

  The fuel vapor generated in the gasoline tank 10 is fed into the case 42 through the vapor introduction pipe 43 and is adsorbed by the adsorbent 41. When the purge control valve 46 is opened, the air introduced from the atmosphere introduction pipe 44 passes through the adsorbent 41 and flows into the surge tank 2b from the purge passage 45a due to the negative pressure in the surge tank 2b. When the atmosphere flows in this way, the fuel vapor adsorbed on the adsorbent 41 is desorbed from the adsorbent 41 and flows into the surge tank portion 2b from the purge passage 45a together with the air introduced from the atmosphere introduction pipe 44. That is, air containing fuel vapor (hereinafter referred to as “purge gas”) is released and introduced (purged) from the canister 40 to the intake passage 2a. Hereinafter, the air contained in the purge gas is referred to as “purge air”, and the fuel vapor contained in the purge gas is referred to as “purge fuel vapor”.

  The purge control valve 46 is duty-controlled by the ECU 30 so that the purge rate (purge gas flow rate / (purge gas flow rate + intake air amount Ga detected by the airflow sensor 32)) becomes a target value. This target value is variably set according to the operating state of the engine 1, and for example, is set so that the purge rate is 10% during idling operation. Further, the purge control valve 46 is controlled so as to execute the purge when all the purge execution conditions (1) to (3) exemplified below are satisfied. (1) The warm-up operation of the engine 1 has been completed. (2) The air-fuel ratio feedback control described later is executed. (3) An accelerator operation is performed.

  Next, various input signals input to the ECU 30 will be described.

  A gasoline running state (first injection state) in which fuel is injected from the gasoline injector 11 and the engine 1 is driven by gasoline, and a hydrogen running state (first injection state) in which fuel is injected from the hydrogen injector 21 and the engine 1 is driven by hydrogen. When the vehicle occupant manually operates the hydrogen operation changeover switch 31 (operation switch) provided in the vehicle interior to switch between the two injection states), the hydrogen operation changeover switch 31 is set in any traveling state according to the operation. A command signal for switching is output to the ECU 30. Then, the ECU 30 switches and controls which of the injectors 11 and 21 is to inject fuel based on a command signal from the hydrogen operation changeover switch 31.

  The intake pipe 2 is provided with a throttle valve 3 for controlling the intake amount, and an airflow sensor 32 for detecting a mass flow rate of intake air (intake amount Ga) is provided upstream of the throttle valve 3 in the intake pipe 2. Is attached. An intake pressure sensor 33 for detecting the pressure in the surge tank 2b (intake pipe pressure Pm) is attached to the downstream side of the throttle valve 3 in the intake pipe 2. The exhaust pipe 4 is provided with an air-fuel ratio sensor 34 that detects the oxygen concentration in the exhaust gas and outputs a signal corresponding to the air-fuel ratio. Detection signals from these sensors 32, 33 and 34 are output to the ECU 30.

  Further, the ECU 30 receives a detection signal from a crank angle sensor 35 that detects the rotation angle of the output shaft (crank shaft) of the engine 1, and based on this detection signal, determines the rotation speed of the crank shaft (engine rotation speed Ne). The ECU 30 can calculate. Further, a purge concentration sensor 36 for detecting the concentration of the evaporated fuel purged from the canister 40 to the intake passage 2a (purge concentration Pc) is attached to the purge pipe 45. The ECU 30 can calculate the flow rate of the evaporated gas (purge evaporated gas) purged from the canister 40 based on detection signals from the purge concentration sensor 36 and the intake pressure sensor 33 (the calculation procedure will be described in detail later).

  The ECU 30 controls the operating state of the engine 1 based on these various detection signals, the accelerator operation amount of the occupant, and the like. Specifically, based on the load required for the engine 1 (for example, intake air amount Ga), the engine speed Ne, and the like, the target opening of the throttle valve 3, the target injection amount of fuel injected from the injectors 11 and 21, and the ignition device 5 To calculate the target ignition timing. Then, the operations of the throttle valve 3, the injectors 11 and 21, the ignition device 5 and the like are controlled so that these target values are obtained.

  The operation of the injectors 11 and 21 is feedback controlled (air / fuel ratio feedback control) based on the value of the air / fuel ratio sensor 34. For example, when the theoretical air-fuel ratio is the target air-fuel ratio, the above-described target injection amount is corrected so that the actual air-fuel ratio calculated based on the detection value of the air-fuel ratio sensor 34 approaches the theoretical air-fuel ratio (FIG. 7). (See step S405). The theoretical air fuel ratio of gasoline is 14.7, whereas the theoretical air fuel ratio of hydrogen is 34.

  By the way, if the fuel vapor is purged during the hydrogen running state in which fuel is injected from the hydrogen injector 21, the fuel injected from the hydrogen injector 21 is hydrogen, while the fuel vapor is gasoline. Two types of fuels having different properties are combusted simultaneously. Then, there is a concern that the combustion state fluctuates greatly. The fluctuation in the combustion state causes a deterioration in the drivability of the vehicle due to an increase in the crankshaft rotation fluctuation, and it becomes difficult to bring the actual air-fuel ratio closer to the target air-fuel ratio, leading to a deterioration in exhaust emission.

  In this embodiment, the target injection amount for the hydrogen injector 21 is corrected based on the inflow amount of purge fuel vapor, the inflow amount of purge air, and the properties of both fuels in this embodiment. In this case, the fluctuation of the combustion state is suppressed. In addition, when purging in the gasoline running state, the target injection amount for the gasoline injector 11 is corrected based on the inflow amount of purge fuel vapor, the inflow amount of purge air, and the properties of the gasoline, thereby suppressing fluctuations in the combustion state. I am trying.

  Next, a processing procedure for performing such correction will be described below with reference to FIGS.

  FIG. 2 is a flowchart showing the correction processing procedure (main routine) executed by the microcomputer included in the ECU 30. This processing is started every time a predetermined period starts after the ignition switch is turned on. It is repeatedly executed at every predetermined crank angle. In the present embodiment, the predetermined period is set as a calculation period (for example, 4 msec) of a CPU included in the microcomputer.

  First, in step S100, it is determined whether or not the currently used fuel is hydrogen and is in a hydrogen running state (hydrogen fuel use determination process). In the subroutine of Step S100 (see FIG. 3), first, in Step S101, it is determined whether or not the hydrogen operation changeover switch 31 is turned on. If the result of this determination is that it is turned on, the hydrogen fuel use judgment flag xhf is set to 1 (S102), and if it is not turned on, the hydrogen fuel use judgment flag xhf is reset to 0 (S103). Terminate the process.

  Next, in step S200 of FIG. 2, it is determined whether purge is being executed in the current operating state (purge execution determination processing). In the subroutine of step S200 (see FIG. 4), first, in step S201, the purge control valve 46 is opened to perform purge based on whether the duty signal to the purge control valve 46 is zero or not. It is determined whether or not. If the result of this determination is that purge execution is in progress, the purge execution flag xprg is set to 1 (S202), and if purge execution is not in progress, the purge execution flag xprg is reset to 0 (S203) and the processing of this subroutine is terminated. To do.

  Next, in step S250 (switching control means) in FIG. 2, it is determined whether or not the hydrogen fuel use determination flag xhf is set to 1. If it is determined that xhf = 1, the mode is switched to the hydrogen running state. In step S300, a correction amount for correcting the target injection amount of hydrogen fuel is calculated (hydrogen fuel correction amount calculation process). In the subsequent step S400, the final target injection amount to be finally injected from the hydrogen injector 21 is determined. Calculate (final hydrogen fuel amount calculation processing).

  On the other hand, when it is determined that xhf = 0, the mode is switched to the gasoline running state. Then, in step S500, a correction amount for correcting the target injection amount of gasoline is calculated (gasoline correction amount calculation process). In the subsequent step S600, a final target injection amount to be finally injected from the gasoline injector 11 is calculated. (Final gasoline amount calculation process).

  Next, the subroutine contents of the hydrogen fuel correction amount calculation process (S300) will be described with reference to FIG.

  First, in step S301, the value of the engine rotational speed Ne calculated based on the detection signal from the crank angle sensor 35 is read. In the subsequent step S302, the intake air amount Ga calculated based on the detection signal from the airflow sensor 32 is read. In the subsequent step S303, the intake pipe pressure Pm calculated based on the detection signal from the intake pressure sensor 33 is read.

  Next, in step S304, based on whether the purge execution flag xprg is set to 1, it is determined whether purge is being executed. If it is determined that purge is not being executed (xprg = 0), the value of the hydrogen fuel correction amount Fh is set to zero in step S305 (second injection amount calculation means when purge is not executed). When it is determined that purge is being executed (xprg = 1), the value of the hydrogen fuel correction amount Fh is calculated in steps S306 to S316 (second injection amount calculation means during purge execution) described below.

  In step S306, the purge concentration Pc calculated based on the detection signal from the purge concentration sensor 36 is read. In subsequent step S307, a pressure difference ΔP between the atmospheric pressure Pa detected by an atmospheric pressure sensor (not shown) and the intake pipe pressure Pm read in step S303 is calculated (ΔP = Pa−Pm).

  In subsequent step S308, based on the pressure difference ΔP calculated in step S307, it is assumed that the opening degree of the purge control valve 46 is fully open (that is, the duty ratio is 100%) (hereinafter referred to as purge gas flow rate Pg100). Calculated). Specifically, FIG. 6A is a map for specifying the relationship between the purge gas flow rate Pg100 and the pressure difference ΔP, and is stored in advance in a memory or the like provided in the ECU 30. In step S308, the purge gas flow rate Pg100 is calculated by reading the value of the purge gas flow rate Pg100 corresponding to the pressure difference ΔP from this map.

  In the subsequent step S309, the purge gas flow rate Pg corresponding to the actual opening of the purge control valve 46 is calculated based on the purge gas flow rate Pg100 calculated in step S308 and the duty ratio of the purge control valve 46. If the pressure difference ΔP is constant, the purge gas flow rate Pg is proportional to the duty ratio Duty (see FIG. 6B). Accordingly, in step S309, the purge gas flow rate Pg (volume flow rate) is calculated by multiplying the purge gas flow rate Pg100 when the purge control valve 46 is fully opened by Duty / 100 (Pg = Pg100 × Duty / 100).

  In the subsequent step S310, the purge fuel vapor amount Pv (volume flow rate) is calculated based on the purge gas flow rate Pg calculated in step S309 and the purge concentration Pc read in step S306 (Pv = Pg × Pc / 100).

  In the subsequent step S311, the purge air vapor amount PK (volume flow rate) is calculated by subtracting the purge fuel vapor amount Pv calculated in step S310 from the purge gas flow rate Pg calculated in step S309 (Pk = Pg−Pv). .

  In the subsequent step S312, the purge fuel vapor equivalent air amount Pkv (mass flow rate), which is the amount of air used when the purge fuel vapor burns at its theoretical air-fuel ratio (air: gasoline = 14.7: 1), Calculation is made based on the purge fuel vapor amount Pv calculated in S310, the gasoline density ρgas, and the theoretical air-fuel ratio of gasoline. Here, the amount of air consumed by the purge fuel vapor (purge fuel) is obtained by multiplying the fuel vapor amount Pv by the gasoline density ρgas and converting it to the mass flow rate, and multiplying this by the theoretical air fuel ratio (14.7) of gasoline. Vapor equivalent air amount Pkv) is calculated (Pkv = Pv × ρgas × 14.7). The air amount Pkv corresponds to the “purge evaporative gas use air amount” described in the claims.

  In the subsequent step S313, the purge air amount PK calculated in step S311 is multiplied by the air density ρair to convert it into a mass flow rate, and the intake air amount Ga read in step S302 is added to this, so that the intake passage 2a The total amount of intake air flowing into the combustion chamber 1a is calculated. Further, by subtracting the purge fuel vapor equivalent air amount Pkv from the total intake air amount calculated in this way, the amount of air supplied to the hydrogen fuel injected from the hydrogen injector 21, that is, the hydrogen fuel should be combusted. An air amount Tt (mass flow rate) is calculated (Tt = Ga + Pk × ρair−Pkv). The air amount Tt corresponds to the “second fuel use air amount” recited in the claims.

  In subsequent step S314, based on the hydrogen fuel calculated in step S313, the amount of air Tt to be burned, the theoretical air-fuel ratio of hydrogen fuel (air: hydrogen fuel = 34: 1), and the engine speed Ne, The amount of hydrogen fuel Th (the amount injected in one combustion stroke of the combustion cycle) is calculated (Th = Tt / 34 / (Ne / 60)).

  In subsequent step S315, based on the engine speed Ne and the engine load (here, the intake air amount Ga), the optimum value (required injection amount) of the hydrogen fuel injection amount in the state where the purge is not executed is set as the base hydrogen fuel amount Thb. calculate. Specifically, FIG. 6C is a map for specifying the relationship between the engine rotational speed Ne, the intake air amount Ga, and the base hydrogen fuel amount Thb, and is stored in advance in a memory or the like provided in the ECU 30. . In step S315, the base hydrogen fuel amount Thb is calculated by reading the base hydrogen fuel amount Thb corresponding to the engine rotational speed Ne and the intake air amount Ga read in steps S301 and S302 from this map. .

  In the subsequent step S316, the difference between the base hydrogen fuel amount Th at the time of purging calculated in step S314 and the base hydrogen fuel amount Thb at the time of non-purging calculated in step S315 is taken to obtain the hydrogen fuel at the time of purging. A correction amount Fh is calculated (Fh = Th−Thb). After calculating the hydrogen fuel correction amount Fh as described above, this subroutine is terminated.

  Next, the contents of the subroutine of the final hydrogen fuel amount calculation process (S400) will be described with reference to FIG.

  First, in step S401, as in step S315, the base hydrogen fuel amount Thb when purge is not executed is read from the map of FIG. 6C. In subsequent step S402, the hydrogen fuel correction amount Fh at the time of purge execution calculated in step S316 of FIG. 5 is read. In step S403, various correction terms such as a water temperature correction value Fthw for correcting the hydrogen fuel amount according to the engine coolant temperature and an intake air temperature correction value Ftha for correcting the hydrogen fuel amount according to the intake air temperature are illustrated. Not read from the map. In subsequent step S404, the total Ftotal of the various correction terms read in steps S402 and S403 is calculated (Ftotal = Fthw + Ftha +... + Fh).

  In the subsequent step S405, a deviation between the actual air-fuel ratio calculated based on the detection signal from the air-fuel ratio sensor 34 and the target air-fuel ratio is calculated, and feedback correction for correcting the hydrogen fuel amount so that this deviation approaches zero. The coefficient faf is calculated.

  In the subsequent step S406, the total Ftotal of the correction term calculated in step S404 is added to the base hydrogen fuel amount Thb read in step S401 when the purge is not executed, and the feedback correction coefficient faf calculated in step S405 is added to this added value. To calculate the final hydrogen fuel amount Tf (Tf = (Thb + Ftotal) × faf). After calculating the final hydrogen fuel amount Tf as described above, this subroutine is terminated.

  Then, the final hydrogen fuel amount Tf calculated in step S400 is set as the target injection amount, and the operation of the hydrogen injector 21 is controlled so that the injection amount of the hydrogen fuel injected from the hydrogen injector 21 becomes the target injection amount.

  Here, correcting the base hydrogen fuel amount Thb with the feedback correction coefficient faf in steps S405 and S406 of FIG. 7 can be said to feedback control the operation of the hydrogen injector 21 based on the actual air-fuel ratio. On the other hand, the hydrogen fuel correction amount Fh is calculated in steps S306 to S316 in FIG. 5 and the base hydrogen fuel amount Thb is calculated in steps S402, S404, and S406 to correct with the hydrogen fuel correction amount Fh. It can be said that the operation of the hydrogen injector 21 is open-loop controlled based on the theoretical air-fuel ratio, the pressure difference ΔP between the atmospheric pressure Pa and the intake pipe pressure Pm, the purge concentration Pc, and the like.

  Next, the subroutine contents of the gasoline correction amount calculation process (S500) will be described with reference to FIG.

  This subroutine basically has the same processing contents as the subroutine of FIG. 5, but differs from the processing of FIG. 5 in that the gasoline correction amount can be calculated without considering the theoretical air-fuel ratio of hydrogen fuel.

  First, in steps S501, S502, and S503, the engine speed Ne, the intake air amount Ga, and the intake pipe pressure Pm are read. Next, if it is determined in step S504 that the purge is not being executed (xprg = 0), the gasoline correction amount Fhg is set to zero in step S505, and if it is determined that the purge is being executed (xprg = 1), the gasoline correction amount Fhg is calculated in steps S506 to S516 described below.

  In the subsequent step S506, the purge concentration Pc is read, and in step S507, a pressure difference ΔP between the atmospheric pressure Pa and the intake pipe pressure Pm is calculated (ΔP = Pa−Pm). In the subsequent step S508, the purge gas flow rate Pg100 is calculated based on the pressure difference ΔP. In the subsequent step S509, the purge gas flow rate Pg corresponding to the actual opening degree of the purge control valve 46 is calculated based on the purge gas flow rate Pg100 and the duty ratio of the purge control valve 46 (Pg = Pg100 × Duty / 100).

  In the subsequent step S510, a purge fuel vapor amount Pv (volume flow rate) is calculated based on the purge gas flow rate Pg and the purge concentration Pc (Pv = Pg × Pc / 100). In the subsequent step S511, the purge air amount PK (volume flow rate) is calculated by subtracting the purge fuel vapor amount Pv from the purge gas flow rate Pg (Pk = Pg−Pv). In the subsequent step S512, the purge fuel vapor equivalent air amount Pkv (mass flow rate) is calculated based on the purge fuel vapor amount Pv, the gasoline density ρgas and the gasoline theoretical air-fuel ratio (Pkv = Pv × ρgas × 14.7).

  In the subsequent step S513, the purge air amount PK is multiplied by the air density ρair to convert it to a mass flow rate, and the intake air amount Ga is added to this to calculate the total intake air amount flowing into the combustion chamber 1a from the intake passage 2a. . Further, by subtracting the purge fuel vapor equivalent air amount Pkv from the total intake air amount calculated in this way, the amount of air supplied to the gasoline injected from the gasoline injector 11, that is, the amount of air to be combusted with gasoline. Ttg (mass flow rate) is calculated (Ttg = Ga + Pk × ρair−Pkv).

  In subsequent step S514, based on the gasoline calculated in step S513, the air amount Ttg to be burned, the theoretical air fuel ratio (14.7) of the gasoline, and the engine rotational speed Ne, the base gasoline amount Thg at the time of purging (the combustion cycle of the combustion cycle). The amount to be injected in one combustion stroke) is calculated (Thg = Ttg / 14.7 / (Ne / 60)).

  In the subsequent step S515, the optimum value (required injection amount) of the gasoline injection amount in the state where the purge is not executed is calculated as the base gasoline amount Thbg based on the engine speed Ne and the engine load (here, the intake air amount Ga). . In the subsequent step S516, the difference between the base gasoline amount Thg at the time of purge execution calculated in step S514 and the base gasoline amount Thbg at the time of non-purge execution calculated in step S515 is taken to obtain the gasoline correction amount Fhg at the time of purge execution. Is calculated (Fhg = Thg−Thbg). After calculating the gasoline correction amount Fhg as described above, this subroutine is terminated.

  The contents of the subroutine of the final gasoline amount calculation process (S600) are the same as the final hydrogen fuel amount calculation process (S400) shown in FIG. Then, the final gasoline fuel amount Tfg calculated in step S600 is set as the target injection amount, and the operation of the gasoline injector 11 is controlled so that the gasoline injection amount injected from the gasoline injector 11 becomes the target injection amount. The ECU 30 during such control corresponds to the second control means described in the claims.

  As described above, according to the present embodiment in which the above control is performed, the purge fuel vapor (purge vaporized gas) is burned at the stoichiometric air-fuel ratio (14.7) when purging is performed in the hydrogen running state. The amount of air Pkv (the amount of purge evaporative gas used) is calculated (S312). In addition, the amount of air Pkv used for the purge fuel vapor is subtracted from the total amount of intake air flowing into the combustion chamber 1a from the intake passage 2a to calculate the amount of air Tt (second fuel usage air amount) to be burned with hydrogen fuel. (S313). Then, when the hydrogen fuel burns at the stoichiometric air-fuel ratio, the base hydrogen fuel amount Th required for the hydrogen fuel and the air amount Tt to be burned is calculated (S314), and the hydrogen is based on the base hydrogen fuel amount Th The target injection amount of the hydrogen fuel injected from the injector 21 is corrected.

  Therefore, it is easy to calculate the target injection amount of hydrogen fuel so as to suppress fluctuations in the combustion state even when purging the fuel vapor and burning both gasoline and hydrogen fuel at the same time in the hydrogen running state it can. Therefore, according to the present embodiment in which the operation of the hydrogen injector 21 is controlled based on the target injection amount calculated in this way, fluctuations in the combustion state caused by the purge of the fuel vapor can be easily suppressed. For this reason, it is possible to suppress an increase in crankshaft rotation fluctuation and suppress a deterioration in vehicle drivability, and to suppress an actual air-fuel ratio from deviating from the target air-fuel ratio, thereby suppressing an exhaust emission deterioration.

(Second Embodiment)
In the first embodiment, when the vehicle occupant turns on the hydrogen operation changeover switch 31, the hydrogen driving state is switched in step S250 (switching control means). On the other hand, in the present embodiment shown in FIG. 9, even when the vehicle occupant is turning on the hydrogen operation changeover switch 31 (S250: YES), in the subsequent step S260 (remaining determination means), the gasoline tank If it is determined that the condition that the remaining amount of gasoline stored in 10 is equal to or greater than a preset threshold value (S260: YES), the mode is forcibly switched to the gasoline running state. The subroutines in steps S100, S200, S250, S300, S400, S500, and S600 are the same as those in the first embodiment.

  According to the present embodiment, it is possible to avoid a situation in which both fuels having different properties are burned at the same time regardless of the operation content of the hydrogen operation changeover switch 31 by the driver. It is possible to easily correct the gasoline target injection amount.

  Note that the threshold th in step S260 may be set to zero or a minute amount. When the minute amount is set, both fuels having different properties are combusted simultaneously. In this case, the hydrogen fuel target injection amount is based on the base hydrogen fuel amount Th as in the first embodiment. Is corrected, the fluctuation of the combustion state can be easily suppressed.

  Incidentally, in carrying out the first embodiment, the remaining amount of hydrogen stored in the hydrogen tank 20 and the gasoline tank when switching between the hydrogen running state and the gasoline running state in step S250 (switching control means) in FIG. Based on the remaining amount of gasoline stored in 10, a restriction may be provided so as not to switch to the use of fuel with a small remaining amount.

(Third embodiment)
In the present embodiment shown in FIG. 10, even if the vehicle occupant is turning on the hydrogen operation changeover switch 31 (S250: YES), if it is determined in step S255 that purging is being performed, the gasoline Forcibly switch to driving state. The subroutines at steps S100, S200, S250, S400, S500, and S600 are the same as those in the first embodiment.

  According to the present embodiment, it is possible to avoid a situation in which both fuels having different properties are burned at the same time regardless of the operation content of the hydrogen operation changeover switch 31 by the driver. It is possible to easily correct the gasoline target injection amount.

  Incidentally, in carrying out this embodiment, in step S250 (switching control means) in FIG. 10, when switching between the hydrogen running state and the gasoline running state, the remaining amount of hydrogen stored in the hydrogen tank 20 and the gasoline tank 10 are changed. Based on the remaining amount of gasoline stored, a restriction may be provided so as not to switch to the use of fuel with a small remaining amount.

(Other embodiments)
The present invention is not limited to the description of the above-described embodiments, and the characteristic configurations of the respective embodiments may be arbitrarily combined. In addition, each of the above embodiments may be modified as follows.

  In the third embodiment, the hydrogen running state and the gasoline running state are switched with priority given to whether or not the purge operation is performed over the operation content of the hydrogen operation switching switch 31. The operation content of the switch 31 may be prioritized and the hydrogen running state and the gasoline running state may be switched.

  In the above embodiment, the purge gas is purged from the canister 40 to the intake passage 2a using the negative pressure (pressure difference ΔP) in the intake passage 2a. Purge gas may be purged into the intake passage 2a using other negative pressure such as exhaust from the suction pump.

The figure which shows the fuel supply system of an engine to which the fuel-injection control apparatus concerning 1st Embodiment of this invention is applied. The flowchart which shows the switching control procedure of the hydrogen running state and gasoline running state performed by ECU of FIG. The subroutine concerning step S100 of FIG. The subroutine concerning step S200 of FIG. The subroutine concerning step S300 of FIG. 6 is a map used in the process of FIG. The subroutine concerning step S400 of FIG. The subroutine concerning step S500 of FIG. In 2nd Embodiment of this invention, the flowchart which shows the switching control procedure of a hydrogen driving state and a gasoline driving state. In 3rd Embodiment of this invention, the flowchart which shows the switching control procedure of a hydrogen driving state and a gasoline driving state.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 11 ... Gasoline injector (1st injector), 21 ... Hydrogen injector (2nd injector), 30 ... ECU (2nd control means, fuel-injection control apparatus), 31 ... Hydrogen operation switching Switch (operation switch), 40... Canister (evaporative gas processing device), S 250... Switching control means, S 260... (Remaining judgment means), S 305 ... second injection amount calculation means when purge is not executed, S 306 to S 316. Second injection amount calculation means at the time.

Claims (8)

An internal combustion engine for switching and injecting a liquid first fuel to be used for combustion and a second fuel having different properties from the first fuel, wherein the first fuel evaporative gas is adsorbed and purged into an intake passage In a fuel injection control device applied to an internal combustion engine equipped with a gas processing device,
Second injection amount calculation means for calculating a second injection amount that is an injection amount of the second fuel based on at least a load state of the internal combustion engine;
Second control means for controlling the operation of a second injector for injecting the second fuel based on the second injection amount;
With
The second injection amount calculation means for executing the purge is based on the purge amount of the evaporated gas to be purged, the properties of the first fuel, and the properties of the second fuel in addition to the load state. A fuel injection control device that calculates two injection amounts. The second injection amount calculation means at the time of purge execution is
The target air-fuel ratio of the first fuel is used as the property of the first fuel, the target air-fuel ratio of the second fuel is used as the property of the second fuel, and
Means for calculating a purge evaporation gas use air amount, which is an air amount used when the purge evaporation gas burns at the target air-fuel ratio;
Means for subtracting the purge evaporative gas use air amount from a total intake air amount flowing into the combustion chamber from the intake passage to calculate a second fuel use air amount that is an air amount supplied to the second fuel; ,
Means for calculating, as the second injection amount, an injection amount of the second fuel necessary for the second fuel use air amount when the second fuel burns at the target air-fuel ratio;
The fuel injection control device according to claim 1, comprising: The second injection amount calculation means at the time of purge execution is
The total intake air amount is calculated by adding the air amount flowing in from the upstream side of the purge passage in the intake passage and the mixed air amount mixed into the intake passage together with the purge evaporative gas. The fuel injection control device according to claim 2, wherein:   The said 2nd control means carries out open loop control of the action | operation of a said 2nd injector based on the said 2nd injection amount calculated by the said 2nd injection amount calculation means, The any one of Claims 1-3 characterized by the above-mentioned. The fuel-injection control apparatus as described in one. A remaining determination means for determining whether or not the tank storage amount of the first fuel remains above a predetermined amount;
Switching control means for switching between a first injection state in which the first fuel is injected from the first injector and a second injection state in which the second fuel is injected from the second injector;
With
The switching control means switches to the first injection state when the purge is executed when it is determined by the remaining determination means that a predetermined amount or more remains. The fuel-injection control apparatus as described in any one. An internal combustion engine for switching and injecting a liquid first fuel to be used for combustion and a second fuel having different properties from the liquid fuel, wherein the evaporated gas adsorbs the evaporated gas of the first fuel and purges it into the intake passage In a fuel injection control device applied to an internal combustion engine provided with a processing device,
Switching control means for switching between a first injection state in which the first fuel is injected from the first injector and a second injection state in which the second fuel is injected from the second injector;
The fuel injection control device, wherein the switching control means switches to the first injection state when the purge is executed. An operation switch that is operated by a driver of the internal combustion engine and outputs a command signal to the switching control means for instructing whether to switch to the first injection state or the second injection state;
7. The fuel injection control device according to claim 5, wherein when the purge is executed, the switching control unit forcibly switches to the first injection state regardless of a command content by the command signal. 8. A fuel injection control device according to any one of claims 1 to 7,
At least one of a first injector for injecting the first fuel, a second injector for injecting the second fuel, and the evaporative gas treatment device;
A fuel injection control system comprising:

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