JP4236556B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection control device for an internal combustion engine that controls an operating state with a fuel injection amount corresponding to a load condition of the internal combustion engine.

  2. Description of the Related Art Conventionally, it is known to obtain an amount of fuel injection based on an engine speed of an internal combustion engine and a change in intake pressure and control the internal combustion engine. As a prior art document related to such a fuel injection control device for an internal combustion engine, one disclosed in Japanese Patent Laid-Open No. 10-280995 is known.

This technique shows a technique for reducing exhaust emissions and improving drivability by accurately calculating the fuel injection amount of each cylinder of a two-cylinder internal combustion engine using an output signal from one intake pressure sensor. Yes.
JP-A-10-280995 (pages 2 to 3)

  In the foregoing, when calculating the fuel injection amount to be supplied to the internal combustion engine, the engine rotational speed and the differential pressure between the atmospheric pressure and the intake bottom pressure are used as parameters. By the way, the inventors have noted that there is still a region where exhaust emission increases or drivability decreases when the throttle opening of the throttle valve is closed. According to experiments and research, the inventors have found that the intake bottom pressure that appears in the vicinity of the end of the intake stroke of the internal combustion engine hardly changes even though the intake air amount has changed in this region. As a result, it has been found that there is a problem that the air-fuel ratio becomes lean and exhaust emission increases and drivability decreases. It was also found that in this region, the intake pressure change in the compression stroke or the expansion (explosion) stroke immediately after the intake bottom pressure changes more remarkably.

  Therefore, the present invention has been made to solve such a problem, and the engine rotational speed and the intake pressure are determined from the engine rotational speed and the intake pressure in all regions having different load conditions including the region where the throttle opening of the throttle valve of the internal combustion engine is closed. It is an object of the present invention to provide a fuel injection control device for an internal combustion engine that can accurately calculate the fuel injection amount to be supplied to the internal combustion engine and can realize exhaust emission reduction and drivability improvement.

According to the fuel injection control device for an internal combustion engine according to claim 1, the engine rotation speed is detected by the engine rotation speed detection means, and the intake pressure in the intake passage downstream of the throttle valve is detected by the intake pressure detection means. In accordance with the load condition of the internal combustion engine, the engine rotational speed stored in the first map storage means and the intake bottom pressure that is the lowest intake pressure in each combustion cycle of the internal combustion engine by the intake bottom pressure calculation means are parameters. Within a predetermined period including at least a compression stroke or an expansion (explosion) stroke in each combustion cycle of the internal combustion engine by the engine rotation speed and the intake average pressure calculation means stored in the first map and the second map storage means The second map using the intake average pressure that is the averaged intake pressure as a parameter is switched, and the operation of the internal combustion engine is performed according to the obtained fuel injection amount. State is controlled. Thus, when calculating the fuel injection amount supplied to the internal combustion engine, the first map corresponding to the medium and high load region of the internal combustion engine and the second map corresponding to the low load region of the internal combustion engine are switched. Therefore, the fuel injection amount to be supplied to the internal combustion engine is accurately calculated from the engine speed and the intake pressure so as to suit all areas where the load conditions of the internal combustion engine are different, thereby reducing exhaust emission and improving drivability. .
Further, in this engine control means , as the load condition of the internal combustion engine, the second map is used when the intake bottom pressure is below a predetermined value, and the first map is used when the intake bottom pressure exceeds the predetermined value, and the fuel injection amount is calculated. Thus, the fuel injection amount supplied to the internal combustion engine is accurately calculated from the engine rotation speed and the intake pressure so as to be adapted to all regions where the load conditions of the internal combustion engine are different.

According to the fuel injection control device for an internal combustion engine according to claim 2, the engine rotation speed is detected by the engine rotation speed detection means, and the intake pressure in the intake passage on the downstream side of the throttle valve is detected by the intake pressure detection means. In accordance with the load condition of the internal combustion engine, the engine rotational speed stored in the first map storage means and the intake bottom pressure that is the lowest intake pressure in each combustion cycle of the internal combustion engine by the intake bottom pressure calculation means are parameters. Within a predetermined period including at least a compression stroke or an expansion (explosion) stroke in each combustion cycle of the internal combustion engine by the engine rotation speed and the intake average pressure calculation means stored in the first map and the second map storage means The second map using the intake average pressure that is the averaged intake pressure as a parameter is switched, and the operation of the internal combustion engine is performed according to the obtained fuel injection amount. State is controlled. Thus, when calculating the fuel injection amount supplied to the internal combustion engine, the first map corresponding to the medium and high load region of the internal combustion engine and the second map corresponding to the low load region of the internal combustion engine are switched. Therefore, the fuel injection amount to be supplied to the internal combustion engine is accurately calculated from the engine speed and the intake pressure so as to suit all areas where the load conditions of the internal combustion engine are different, thereby reducing exhaust emission and improving drivability. .
Further, in this engine control means , as the load condition of the internal combustion engine, the second map is used when the intake average pressure is not more than a predetermined value, and the first map is used when the intake pressure exceeds the predetermined value, and the fuel injection amount is calculated. Thus, the fuel injection amount supplied to the internal combustion engine is accurately calculated from the engine rotation speed and the intake pressure so as to be adapted to all regions where the load conditions of the internal combustion engine are different.

According to the fuel injection control device for an internal combustion engine of claim 3, the engine rotation speed is detected by the engine rotation speed detection means, and the intake pressure in the intake passage on the downstream side of the throttle valve is detected by the intake pressure detection means. In accordance with the load condition of the internal combustion engine, the engine rotational speed stored in the first map storage means and the intake bottom pressure that is the lowest intake pressure in each combustion cycle of the internal combustion engine by the intake bottom pressure calculation means are parameters. Within a predetermined period including at least a compression stroke or an expansion (explosion) stroke in each combustion cycle of the internal combustion engine by the engine rotation speed and the intake average pressure calculation means stored in the first map and the second map storage means The second map using the intake average pressure that is the averaged intake pressure as a parameter is switched, and the operation of the internal combustion engine is performed according to the obtained fuel injection amount. State is controlled. Thus, when calculating the fuel injection amount supplied to the internal combustion engine, the first map corresponding to the medium and high load region of the internal combustion engine and the second map corresponding to the low load region of the internal combustion engine are switched. Therefore, the fuel injection amount to be supplied to the internal combustion engine is accurately calculated from the engine speed and the intake pressure so as to suit all areas where the load conditions of the internal combustion engine are different, thereby reducing exhaust emission and improving drivability. .
Further, in this engine control means , the second map is used when the throttle opening degree of the throttle valve detected by the throttle opening degree detection means as a load condition of the internal combustion engine is equal to or smaller than a predetermined value, and the first map is used when it exceeds a predetermined value. And the fuel injection amount is calculated. Thus, the fuel injection amount supplied to the internal combustion engine is accurately calculated from the engine rotation speed and the intake pressure so as to be adapted to all regions where the load conditions of the internal combustion engine are different.

According to the fuel injection control device for an internal combustion engine of claim 4, the engine speed is detected by the engine speed detecting means, and the intake pressure in the intake passage on the downstream side of the throttle valve is detected by the intake pressure detecting means. In accordance with the load condition of the internal combustion engine, the engine rotational speed stored in the first map storage means and the intake bottom pressure that is the lowest intake pressure in each combustion cycle of the internal combustion engine by the intake bottom pressure calculation means are parameters. Within a predetermined period including at least a compression stroke or an expansion (explosion) stroke in each combustion cycle of the internal combustion engine by the engine rotation speed and the intake average pressure calculation means stored in the first map and the second map storage means The second map using the intake average pressure that is the averaged intake pressure as a parameter is switched, and the operation of the internal combustion engine is performed according to the obtained fuel injection amount. State is controlled. Thus, when calculating the fuel injection amount supplied to the internal combustion engine, the first map corresponding to the medium and high load region of the internal combustion engine and the second map corresponding to the low load region of the internal combustion engine are switched. Therefore, the fuel injection amount to be supplied to the internal combustion engine is accurately calculated from the engine speed and the intake pressure so as to suit all areas where the load conditions of the internal combustion engine are different, thereby reducing exhaust emission and improving drivability. .
Further, in this engine control means , as a load condition of the internal combustion engine, when the idle detection means detects that the throttle valve is in the vicinity of the fully closed state, the second map, and when it is detected that the throttle valve is not in the vicinity of the fully closed state, the second map. 1 is used to calculate the fuel injection amount. Thus, the fuel injection amount supplied to the internal combustion engine is accurately calculated from the engine rotation speed and the intake pressure so as to be adapted to all regions where the load conditions of the internal combustion engine are different.

In the fuel injection control device for an internal combustion engine according to claim 5, the internal combustion engine is a single cylinder or a multi-cylinder composed of independent intake air. In the multi-cylinder internal combustion engine composed of these single cylinders or independent intakes, the intake pressure fluctuation easily appears in each combustion cycle, and the intake bottom pressure and the intake average pressure are accurately calculated.

  Hereinafter, the best mode for carrying out the present invention will be described based on examples.

  FIG. 1 is a schematic configuration diagram showing an internal combustion engine and its peripheral devices to which a fuel injection control device for an internal combustion engine according to an embodiment of the present invention is applied.

In FIG. 1, reference numeral 1 denotes an internal combustion engine (single cylinder engine) composed of one cylinder, and air from an air cleaner 3 is introduced into an intake passage 2 of the internal combustion engine 1. A throttle valve 11 that is opened and closed in conjunction with an operation of an accelerator pedal (not shown) as a driver (driver) request is disposed in the middle of the intake passage 2. By opening and closing the throttle valve 11, the intake air amount to the intake passage 2 is adjusted. Simultaneously with the intake air amount, fuel pressure via a pressure-regulation data is pumped by the fuel pump from a fuel tank (not shown) tone, it is disposed in the intake passage 2 in the vicinity of the intake port 4 of the internal combustion engine 1 The fuel is injected from an injector (fuel injection valve) 5. Then, an air-fuel mixture composed of a predetermined fuel injection amount and intake air amount is sucked into the combustion chamber 7 via the intake valve 6.

  A throttle opening sensor 21 for detecting a throttle opening degree TA corresponding to an accelerator pedal depression amount or the like is disposed in the throttle valve 11 in the intake passage 2. The throttle opening sensor 21 incorporates an idle SW (switch) (not shown) that detects that the throttle valve 11 is in the vicinity of full closure. An intake pressure sensor 22 that detects the intake pressure PM in the intake passage 2 is disposed on the downstream side of the throttle valve 11. The internal combustion engine 1 is provided with a water temperature sensor 23 for detecting the cooling water temperature THW. Further, a crank angle sensor 24 for detecting a crank angle [° CA (Crank Angle)] accompanying the rotation is disposed on the crankshaft 13 of the internal combustion engine 1. Based on the crank angle detected by the crank angle sensor 24, the engine speed NE of the internal combustion engine 1 is calculated.

  A spark plug 14 is disposed toward the combustion chamber 7 of the internal combustion engine 1. The ignition plug 14 has a high voltage from an ignition coil / igniter 15 based on an ignition command signal output from an ECU (Electronic Control Unit) 30 described later in synchronization with a crank angle detected by a crank angle sensor 24. A voltage is applied, and ignition combustion is performed on the air-fuel mixture in the combustion chamber 7. In this way, the air-fuel mixture in the combustion chamber 7 is combusted (expanded) to obtain driving force, and the exhaust gas after combustion is led out from the exhaust manifold to the exhaust passage 9 via the exhaust valve 8 and discharged to the outside. The

  The ECU 30 includes a CPU 31 as a central processing unit that executes various known arithmetic processes, a ROM 32 that stores control programs and control maps, a RAM 33 that stores various data, a B / U (backup) RAM 34, an input / output circuit 35, It is configured as a logical operation circuit composed of a bus line 36 etc. for connecting them. The ECU 30 receives the throttle opening TA from the throttle opening sensor 21, the intake pressure PM from the intake pressure sensor 22, the cooling water temperature THW from the water temperature sensor 23, the engine speed NE from the crank angle sensor 24, and the like. ing. Based on the output signals from the ECU 30 based on these various sensor information, the injector 5 related to the fuel injection timing and the fuel injection amount, the spark plug 14 related to the ignition timing, the ignition coil / igniter 15 and the like are appropriately controlled.

  Next, referring to FIG. 4 based on the flowchart of FIG. 2 showing the processing procedure of the intake bottom pressure PMB calculation in the CPU 31 in the ECU 30 used in the fuel injection control device of the internal combustion engine according to one embodiment of the present invention. I will explain. Here, FIG. 4 is a time chart showing transition states of various sensor signals and various control amounts corresponding to the processing of FIG. 2 and FIG. 3 described later. Further, the intake, compression, expansion (explosion), and exhaust strokes shown in FIG. 4 are detected based on a cam angle signal from a cam angle sensor (not shown) and a crank angle signal from a crank angle sensor 24. The symbol position indicates a compression TDC (Top Dead Center) in the cylinder of the internal combustion engine 1. The intake bottom pressure calculation routine is repeatedly executed by the CPU 31 every predetermined time.

  In FIG. 2, first, in step S101, the current intake pressure PM is read. Next, the routine proceeds to step S102, where it is determined whether or not the crank angle signal counter NNUM is a predetermined value α (for example, “7” representing the end position of the expansion (explosion) stroke shown in FIG. 4). In the crank angle signal counter NNUM, for example, a reference detected by a crank angle sensor 24 disposed on the crankshaft 13 of the internal combustion engine 1 in response to generation of a cam angle signal from a cam angle sensor (not shown). For one combustion cycle of 720 [° CA (Crank Angle)] consisting of 4 cycles (intake stroke-> compression stroke-> expansion (explosion) stroke-> exhaust stroke) with the crank angle position set to "0 (zero)" This is a value representing each crank angle position “0” to “23” that is incremented by “+1” every 30 [° CA] when the crank angle signal is input. When “23” is exceeded, it is cleared to “0”. Count-up processing is repeatedly executed.

  When the determination condition of step S102 is satisfied, that is, when the crank angle signal counter NNUM is a predetermined value α (time t0, time t2 shown in FIG. 4), the process proceeds to step S103, and the intake bottom pressure PMB is preset. Initially set to a predetermined maximum value. On the other hand, when the determination condition of step S102 is not satisfied, that is, when the crank angle signal counter NNUM is other than the predetermined value α, step S103 is skipped.

  Next, the routine proceeds to step S104, where it is determined whether the intake bottom pressure PMB exceeds the current intake pressure PM. When the determination condition in step S104 is satisfied, that is, when the intake bottom pressure PMB exceeds the current intake pressure PM, the process proceeds to step S105, the intake bottom pressure PMB is updated to the current intake pressure PM, and this routine is terminated.

  On the other hand, when the determination condition of step S104 is not satisfied, that is, when the intake bottom pressure PMB is small below the current intake pressure PM, the current intake pressure PM cannot be the intake bottom pressure PMB, so step S105 is skipped, This routine ends.

  As shown in FIG. 4, the intake pressure PM in the system in which the internal combustion engine 1 detects the intake pressure in a single cylinder engine (including a multi-cylinder engine) as in the present embodiment becomes a negative pressure in the intake stroke, After the intake stroke is completed, the air gradually rises in the atmospheric pressure direction by the air flowing into the intake passage 2 from the gap of the throttle valve 11. Therefore, the intake bottom pressure PMB is successively updated by the above-described intake bottom pressure calculation routine, and the intake bottom pressure PMB at time t1 shown in FIG. 4 is changed to the intake bottom pressure PMB in the current one combustion cycle (720 [° CA]). It is detected as [kPa: kilopascals].

  Next, referring to FIG. 4 based on the flowchart of FIG. 3 showing the processing procedure of the intake average pressure PMAV calculation in the CPU 31 in the ECU 30 used in the fuel injection control device of the internal combustion engine according to one embodiment of the present invention. I will explain. The intake average pressure calculation routine is repeatedly executed by the CPU 31 every predetermined time within a predetermined period including at least a compression stroke and an expansion (explosion) stroke in each combustion cycle of the internal combustion engine 1.

  In FIG. 3, first, in step S201, it is determined whether or not the crank angle signal counter NNUM is equal to or greater than a predetermined value β (for example, “19” representing the start position of the compression stroke shown in FIG. 4). When the determination condition of step S201 is not satisfied, that is, when the crank angle signal counter NNUM is smaller than the predetermined value β, the process proceeds to step S202, and the intake pressure integration counter C is cleared to “0”. Next, the routine proceeds to step S203, where the intake pressure integrated value PMSM is cleared to “0”, and this routine ends.

  On the other hand, when the determination condition of step S201 is satisfied, that is, when the crank angle signal counter NNUM is larger than the predetermined value β, the process proceeds to step S204, where the crank angle signal counter NNUM is set to the predetermined value γ (for example, expansion (explosion shown in FIG. 4). It is determined whether it is less than “7” representing the end position of the stroke). When the determination condition of step S204 is satisfied, that is, when the crank angle signal counter NNUM is in the range from the predetermined value β to the predetermined value γ, the process proceeds to step S205, and this time is detected as the previous intake pressure integrated value PMSMO. The intake pressure PM is added to calculate the intake pressure integrated value PMSM.

  As described above, the crank angle signal counter NNUM in the present embodiment is set to a crank angle range in the intake stroke and the compression stroke in the range from the predetermined value β to the predetermined value γ, and one combustion cycle of the internal combustion engine 1 is set. Each time corresponds to a predetermined period including at least a compression stroke and an expansion (explosion) stroke. Next, the routine proceeds to step S206, where the intake pressure integration counter C is incremented by "+1", and this routine ends.

  On the other hand, if the determination condition in step S204 is not satisfied, that is, if the crank angle signal counter NNUM is greater than or equal to the predetermined value γ, the process proceeds to step S207, and the intake pressure integrated value PMSM calculated in step S205 is the integrated counter in step S206. The intake air average pressure PMAV is calculated by dividing by C, and this routine is terminated.

  Next, a description will be given based on the flowchart of FIG. 5 showing the processing procedure of the basic fuel injection amount TP calculation in the CPU 31 in the ECU 30 used in the fuel injection control device of the internal combustion engine according to one embodiment of the present invention. The basic fuel injection amount calculation routine is repeatedly executed by the CPU 31 at every predetermined timing of one combustion cycle.

  In FIG. 5, the engine speed NE is read in step S301. Next, the routine proceeds to step S302, where the intake bottom pressure PMB calculated in FIG. 2 is read. Next, the routine proceeds to step S303, where the intake average pressure PMAV calculated in FIG. 3 is read. Next, the process proceeds to step S304, and it is determined whether the intake bottom pressure PMB read in step S302 is equal to or less than a predetermined value δ. When the determination condition of step S304 is satisfied, that is, when the intake bottom pressure PMB is as small as the predetermined value δ or less and the operating state of the internal combustion engine 1 is assumed to be in the vicinity of the idle rotation speed, the routine proceeds to step S305. In step S305, the basic fuel injection amount TP is calculated from the engine rotational speed NE read in step S301 and the intake average pressure PMAV read in step S303 using a map stored in advance in the ROM 32, and this routine is executed. Exit.

  On the other hand, when the determination condition of step S304 is not satisfied, that is, when the intake bottom pressure PMB is larger than the predetermined value δ and it is assumed that the operating state of the internal combustion engine 1 is not near the idle rotation speed, the routine proceeds to step S306. In step S306, the basic fuel injection amount TP is calculated from the engine speed NE read in step S301 and the intake bottom pressure PMB read in step S302 using a map stored in advance in the ROM 32, and this routine is executed. Exit. It should be noted that various corrections are performed on the basic fuel injection amount TP calculated in this routine as is well known, and the final fuel injection amount TAU supplied from the injector 5 to the internal combustion engine 1 is set.

  As described above, the fuel injection control device for the internal combustion engine according to this embodiment includes the crank angle sensor 24 as the engine rotation speed detecting means for detecting the engine rotation speed NE of the internal combustion engine 1 and the downstream of the throttle valve 11 of the internal combustion engine 1. An intake pressure sensor 22 as an intake pressure detection means for detecting the intake pressure PM in the intake passage 2 on the side, and a CPU 31 in the ECU 30 that calculates the minimum intake pressure for each combustion cycle of the internal combustion engine 1 as the intake bottom pressure PMB. In the ECU 30 which calculates the intake bottom pressure calculating means to be achieved and the intake pressure averaged over a predetermined period including at least the compression stroke or the expansion (explosion) stroke in each combustion cycle of the internal combustion engine 1 as the intake average pressure PMAV. The intake average pressure calculating means achieved by the CPU 31, the engine speed NE and the intake bottom pressure PMB are used as parameters. A ROM 32 in the ECU 30 serving as a first map storage means for storing a first map for calculating a basic fuel injection amount TP to be supplied to the internal combustion engine 1, an engine rotational speed NE and an intake average pressure PMAV as parameters, and an internal combustion engine ROM 32 in the ECU 30 as a second map storage means for storing a second map for calculating the basic fuel injection amount TP to be supplied to 1, and the first map and the second map according to the load condition of the internal combustion engine 1 Engine control means achieved by the CPU 31 in the ECU 30 for controlling the operating state of the internal combustion engine 1 with the final fuel injection amount TAU obtained by performing various corrections on the basic fuel injection amount TP obtained at that time. To do. The internal combustion engine 1 is a single cylinder.

  That is, when the basic fuel injection amount TP supplied to the internal combustion engine 1 is calculated, the first map using the engine speed NE and the intake bottom pressure PMB as parameters, the engine speed NE and the intake average pressure PMAV as parameters. By switching to the second map, the final fuel injection amount TAU supplied to the internal combustion engine 1 from the engine rotational speed NE and the intake pressure PM is accurately calculated so as to suit all areas where the load conditions of the internal combustion engine 1 are different. It is possible to reduce exhaust emissions and improve drivability. Note that if the internal combustion engine 1 is a single cylinder, the intake pressure fluctuation easily appears in each combustion cycle, and the intake bottom pressure PMB and the intake average pressure PMAV can be accurately calculated.

  Further, the engine control means achieved by the CPU 31 in the ECU 30 of the fuel injection control device for the internal combustion engine of the present embodiment is stored in the ROM 32 as the load condition of the internal combustion engine 1 when the intake bottom pressure PMB is not more than a predetermined value δ. When the intake bottom pressure PMB exceeds a predetermined value δ, the basic fuel injection amount TP is calculated using the first map stored in the ROM 32.

  That is, in the low load region of the internal combustion engine 1 where the intake bottom pressure PMB is equal to or less than the predetermined value δ, the second map using the engine speed NE and the intake average pressure PMAV as parameters is used. In the middle and high load region of the internal combustion engine 1 where the pressure PMB exceeds the predetermined value δ, the first map using the engine speed NE and the intake bottom pressure PMB as parameters is used, and the basic fuel injection supplied to the internal combustion engine 1 is used. A quantity TP is calculated. As a result, the final fuel injection amount TAU supplied to the internal combustion engine 1 can be accurately calculated from the engine rotational speed NE and the intake pressure PM so as to be adapted to all regions where the load conditions of the internal combustion engine 1 are different, thereby reducing exhaust emissions and driving performance. Improvements can be realized.

  Next, FIG. 6 is a flowchart showing a first modified example of the processing procedure of the basic fuel injection amount TP calculation in the CPU 31 in the ECU 30 used in the fuel injection control device for the internal combustion engine according to the embodiment of the present invention. This will be explained based on. The basic fuel injection amount calculation routine is repeatedly executed by the CPU 31 at every predetermined timing of one combustion cycle.

  In FIG. 6, the engine speed NE is read in step S401. Next, the routine proceeds to step S402, where the intake bottom pressure PMB calculated in FIG. 2 is read. Next, the routine proceeds to step S403, where the intake average pressure PMAV calculated in FIG. 3 is read. Next, the process proceeds to step S404, and it is determined whether the intake average pressure PMAV read in step S403 is equal to or less than a predetermined value ε. If the determination condition in step S404 is satisfied, that is, if the intake average pressure PMAV is as small as a predetermined value ε or less and the operating state of the internal combustion engine 1 is assumed to be in the vicinity of the idle rotation speed, the routine proceeds to step S405. In step S405, the basic fuel injection amount TP is calculated from the engine rotational speed NE read in step S401 and the intake average pressure PMAV read in step S403 using a map stored in advance in the ROM 32, and this routine is executed. Exit.

  On the other hand, when the determination condition of step S404 is not satisfied, that is, when the intake average pressure PMAV is larger than the predetermined value ε and it is assumed that the operating state of the internal combustion engine 1 is not in the vicinity of the idle rotation speed, the routine proceeds to step S406. In step S406, the basic fuel injection amount TP is calculated from the engine rotational speed NE read in step S401 and the intake bottom pressure PMB read in step S402 using a map stored in advance in the ROM 32, and this routine is executed. Exit. It should be noted that various corrections are performed on the basic fuel injection amount TP calculated in this routine as is well known, and the final fuel injection amount TAU supplied from the injector 5 to the internal combustion engine 1 is set.

  As described above, the engine control means achieved by the CPU 31 in the ECU 30 of the fuel injection control device for the internal combustion engine of the present modification is as follows. The basic fuel injection amount TP is calculated using the first map stored in the ROM 32 when the intake average pressure PMAV exceeds the predetermined value ε.

  That is, in the low load region of the internal combustion engine 1 where the average intake air pressure PMAV is equal to or less than the predetermined value ε, the second map using the engine speed NE and the average intake air pressure PMAV as parameters is used. In the middle and high load region of the internal combustion engine 1 where the pressure PMAV exceeds the predetermined value ε, the first map using the engine speed NE and the intake bottom pressure PMB as parameters is used, and the basic fuel injection supplied to the internal combustion engine 1 is used. A quantity TP is calculated. As a result, the final fuel injection amount TAU supplied to the internal combustion engine 1 can be accurately calculated from the engine rotational speed NE and the intake pressure PM so as to be adapted to all the regions where the load conditions of the internal combustion engine 1 are different, thereby reducing exhaust emission and drivability. Improvements can be realized.

  Next, a flowchart of FIG. 7 showing a second modification of the processing procedure of the basic fuel injection amount TP calculation in the CPU 31 in the ECU 30 used in the fuel injection control device of the internal combustion engine according to one embodiment of the present invention is shown. This will be explained based on. The basic fuel injection amount calculation routine is repeatedly executed by the CPU 31 at every predetermined timing of one combustion cycle.

  In FIG. 7, the engine speed NE is read in step S501. Next, the routine proceeds to step S502, where the throttle opening degree TA is read. Next, the routine proceeds to step S503, where the intake bottom pressure PMB calculated in FIG. 2 is read. Next, the routine proceeds to step S504, where the intake average pressure PMAV calculated in FIG. 3 is read. Next, the process proceeds to step S505, and it is determined whether the throttle opening degree TA read in step S502 is equal to or smaller than a predetermined value ζ. When the determination condition of step S505 is satisfied, that is, when the throttle opening degree TA is as small as the predetermined value ζ or less and the operation state of the internal combustion engine 1 is assumed to be in the vicinity of the idle rotation speed, the process proceeds to step S506. In step S506, the basic fuel injection amount TP is calculated from the engine speed NE read in step S501 and the intake average pressure PMAV read in step S504 using a map stored in advance in the ROM 32, and this routine is executed. Exit.

  On the other hand, when the determination condition of step S505 is not satisfied, that is, when the throttle opening degree TA is larger than the predetermined value ζ and it is assumed that the operating state of the internal combustion engine 1 is not near the idle rotation speed, the process proceeds to step S507. In step S507, the basic fuel injection amount TP is calculated from the engine speed NE read in step S501 and the intake bottom pressure PMB read in step S503 using a map stored in advance in the ROM 32, and this routine is executed. Exit. It should be noted that various corrections are performed on the basic fuel injection amount TP calculated in this routine as is well known, and the final fuel injection amount TAU supplied from the injector 5 to the internal combustion engine 1 is set.

  As described above, the fuel injection control device for the internal combustion engine of the present modification includes the throttle opening degree sensor 21 as the throttle opening degree detecting means for detecting the throttle opening degree TA of the throttle valve 11, and the CPU 31 in the ECU 30 The engine control means to be achieved uses the second map stored in the ROM 32 when the throttle opening TA is equal to or less than the predetermined value ζ as the load condition of the internal combustion engine 1, and the throttle opening TA exceeds the predetermined value ζ. Sometimes, the basic fuel injection amount TP is calculated using the first map stored in the ROM 32.

  That is, in the low load region of the internal combustion engine 1 where the throttle opening degree TA is equal to or less than the predetermined value ζ, the second map using the engine speed NE and the intake average pressure PMAV as parameters is used. In a medium and high load region where the degree TA exceeds a predetermined value ζ, the first map using the engine speed NE and the intake bottom pressure PMB as parameters is used, and the basic fuel injection supplied to the internal combustion engine 1 is used. A quantity TP is calculated. As a result, the final fuel injection amount TAU supplied to the internal combustion engine 1 can be accurately calculated from the engine rotational speed NE and the intake pressure PM so as to be adapted to all the regions where the load conditions of the internal combustion engine 1 are different, thereby reducing exhaust emission and drivability. Improvements can be realized.

  Next, a flowchart of FIG. 8 showing a third modification of the processing procedure of the basic fuel injection amount TP calculation in the CPU 31 in the ECU 30 used in the fuel injection control device of the internal combustion engine according to one embodiment of the present invention is shown. This will be explained based on. The basic fuel injection amount calculation routine is repeatedly executed by the CPU 31 at every predetermined timing of one combustion cycle.

  In FIG. 8, the engine speed NE is read in step S601. Next, the routine proceeds to step S602, where the intake bottom pressure PMB calculated in FIG. 2 is read. Next, the routine proceeds to step S603, where the intake average pressure PMAV calculated in FIG. 3 is read. Next, the process proceeds to step S604, where it is determined whether the idle SW is “ON”. When the determination condition in step S604 is satisfied, that is, when the idle SW is “ON” and the operation state of the internal combustion engine 1 is assumed to be at the idle rotation speed, the process proceeds to step S605. In step S605, the basic fuel injection amount TP is calculated from the engine speed NE read in step S601 and the intake average pressure PMAV read in step S603 using a map stored in advance in the ROM 32, and this routine is executed. Exit.

  On the other hand, when the determination condition of step S604 is not satisfied, that is, when the idle SW is “OFF (off)” and the operation state of the internal combustion engine 1 is not in the vicinity of the idle rotation speed, the process proceeds to step S606. In step S606, the basic fuel injection amount TP is calculated from the engine speed NE read in step S601 and the intake bottom pressure PMB read in step S602 using a map stored in advance in the ROM 32, and this routine is executed. Exit. It should be noted that various corrections are performed on the basic fuel injection amount TP calculated in this routine as is well known, and the final fuel injection amount TAU supplied from the injector 5 to the internal combustion engine 1 is set.

  As described above, the fuel injection control device for the internal combustion engine of the present modification includes the idle SW (not shown) as idle detection means for detecting the vicinity of the fully closed throttle valve 11, and is achieved by the CPU 31 in the ECU 30. When the engine control means detects that the idle SW is "ON" as the load condition of the internal combustion engine 1 and the throttle valve 11 is in the vicinity of the fully closed state, the engine control means uses the second map stored in the ROM 32 to Is “OFF”, and when it is detected that the throttle valve 11 is not in the vicinity of full closure, the basic fuel injection amount TP is calculated using the first map stored in the ROM 32.

  That is, in the low load region of the internal combustion engine 1 where the idle SW is “ON”, the second map using the engine speed NE and the intake average pressure PMAV as parameters is used, and the idle SW is set to “OFF”. In the middle and high load region of the internal combustion engine 1, the first map using the engine speed NE and the intake bottom pressure PMB as parameters is used, and the basic fuel injection amount TP supplied to the internal combustion engine 1 is calculated. The As a result, the final fuel injection amount TAU supplied to the internal combustion engine 1 can be accurately calculated from the engine rotational speed NE and the intake pressure PM so as to be adapted to all regions where the load conditions of the internal combustion engine 1 are different, thereby reducing exhaust emissions and driving performance. Improvements can be realized.

  By the way, in the above-described embodiments and modifications, the case where the internal combustion engine is a single-cylinder engine has been described. However, the present invention is not limited to this, and each cylinder includes a plurality of cylinders. In the case of an independent intake multi-cylinder engine that supplies the intake air amount independently, the same action and effect can be expected.

  Further, in the above-described embodiments and modifications, the intake bottom pressure PMB is calculated based on the intake pressure PM at every predetermined time. However, the present invention is not limited to this, and the crank angle sensor is not limited thereto. 24 may be calculated for each input of the crank angle signal from 24, or may be calculated by providing a peak hold circuit in the ECU 30.

FIG. 1 is a schematic configuration diagram showing an internal combustion engine to which a fuel injection control device for an internal combustion engine according to an example of an embodiment of the present invention is applied and its peripheral devices. FIG. 2 is a flowchart showing the processing procedure of the intake bottom pressure calculation in the CPU in the ECU used in the fuel injection control device for the internal combustion engine according to an example of the embodiment of the present invention. FIG. 3 is a flowchart showing a processing procedure for calculating the average intake air pressure in the CPU in the ECU used in the fuel injection control device for an internal combustion engine according to an example of the embodiment of the present invention. FIG. 4 is a time chart showing transition states of various sensor signals and various control amounts corresponding to the processes of FIGS. FIG. 5 is a flowchart showing a basic fuel injection amount calculation processing procedure in the CPU in the ECU used in the fuel injection control device for an internal combustion engine according to an embodiment of the present invention. FIG. 6 is a flowchart showing a first modification of the processing procedure of basic fuel injection amount calculation in the CPU in the ECU used in the fuel injection control device for an internal combustion engine according to an embodiment of the present invention. is there. FIG. 7 is a flowchart showing a second modification of the processing procedure of basic fuel injection amount calculation in the CPU in the ECU used in the fuel injection control device for an internal combustion engine according to an embodiment of the present invention. is there. FIG. 8 is a flowchart showing a third modification of the processing procedure of basic fuel injection amount calculation in the CPU in the ECU used in the fuel injection control device for an internal combustion engine according to an embodiment of the present invention. is there.

Explanation of symbols

1 Internal combustion engine 2 Intake passage 5 Injector (fuel injection valve)
11 Throttle valve 21 Throttle opening sensor 22 Intake pressure sensor 24 Crank angle sensor 30 ECU (electronic control unit)

Claims (5)

Engine rotation speed detection means for detecting the engine rotation speed of the internal combustion engine;
An intake pressure detecting means for detecting an intake pressure in an intake passage downstream of the throttle valve of the internal combustion engine;
An intake bottom pressure calculating means for calculating a minimum intake pressure for each combustion cycle of the internal combustion engine as an intake bottom pressure;
An intake air average pressure calculating means for calculating an intake air pressure averaged within a predetermined period including at least a compression stroke or an expansion (explosion) stroke in each combustion cycle of the internal combustion engine as an intake air average pressure;
First map storage means for storing a first map for calculating a fuel injection amount to be supplied to the internal combustion engine using the engine rotation speed and the intake bottom pressure as parameters;
Second map storage means for storing a second map for calculating a fuel injection amount to be supplied to the internal combustion engine, using the engine rotation speed and the intake average pressure as parameters;
Engine control means for switching the first map and the second map according to the load condition of the internal combustion engine, and controlling the operating state of the internal combustion engine with the fuel injection amount obtained at that time ,
The engine control means uses the second map when the intake bottom pressure is a predetermined value or less as a load condition of the internal combustion engine, and uses the first map when the intake bottom pressure exceeds a predetermined value. A fuel injection control device for an internal combustion engine, which calculates a fuel injection amount . Engine rotation speed detection means for detecting the engine rotation speed of the internal combustion engine;
An intake pressure detecting means for detecting an intake pressure in an intake passage downstream of the throttle valve of the internal combustion engine;
An intake bottom pressure calculating means for calculating a minimum intake pressure for each combustion cycle of the internal combustion engine as an intake bottom pressure;
An intake air average pressure calculating means for calculating an intake air pressure averaged within a predetermined period including at least a compression stroke or an expansion (explosion) stroke in each combustion cycle of the internal combustion engine as an intake air average pressure;
First map storage means for storing a first map for calculating a fuel injection amount to be supplied to the internal combustion engine using the engine rotation speed and the intake bottom pressure as parameters;
Second map storage means for storing a second map for calculating a fuel injection amount to be supplied to the internal combustion engine, using the engine rotation speed and the intake average pressure as parameters;
Engine control means for switching the first map and the second map according to the load condition of the internal combustion engine, and controlling the operating state of the internal combustion engine with the fuel injection amount obtained at that time,
The engine control means uses the second map as the load condition of the internal combustion engine when the intake average pressure is a predetermined value or less, and uses the first map when the intake average pressure exceeds a predetermined value. A fuel injection control device for an internal combustion engine, which calculates a fuel injection amount. Engine rotation speed detection means for detecting the engine rotation speed of the internal combustion engine;
An intake pressure detecting means for detecting an intake pressure in an intake passage downstream of the throttle valve of the internal combustion engine;
An intake bottom pressure calculating means for calculating a minimum intake pressure for each combustion cycle of the internal combustion engine as an intake bottom pressure;
An intake air average pressure calculating means for calculating an intake air pressure averaged within a predetermined period including at least a compression stroke or an expansion (explosion) stroke in each combustion cycle of the internal combustion engine as an intake air average pressure;
First map storage means for storing a first map for calculating a fuel injection amount to be supplied to the internal combustion engine using the engine rotation speed and the intake bottom pressure as parameters;
Second map storage means for storing a second map for calculating a fuel injection amount to be supplied to the internal combustion engine, using the engine rotation speed and the intake average pressure as parameters;
Engine control means for switching between the first map and the second map according to a load condition of the internal combustion engine, and controlling an operating state of the internal combustion engine with the fuel injection amount obtained at that time;
Comprising throttle opening detection means for detecting the throttle opening of the throttle valve;
The engine control means uses the second map as a load condition of the internal combustion engine when the throttle opening is equal to or smaller than a predetermined value, and uses the first map when the throttle opening exceeds a predetermined value. A fuel injection control device for an internal combustion engine, which calculates a fuel injection amount. Engine rotation speed detection means for detecting the engine rotation speed of the internal combustion engine;
An intake pressure detecting means for detecting an intake pressure in an intake passage downstream of the throttle valve of the internal combustion engine;
An intake bottom pressure calculating means for calculating a minimum intake pressure for each combustion cycle of the internal combustion engine as an intake bottom pressure;
An intake air average pressure calculating means for calculating an intake air pressure averaged within a predetermined period including at least a compression stroke or an expansion (explosion) stroke in each combustion cycle of the internal combustion engine as an intake air average pressure;
First map storage means for storing a first map for calculating a fuel injection amount to be supplied to the internal combustion engine using the engine rotation speed and the intake bottom pressure as parameters;
Second map storage means for storing a second map for calculating a fuel injection amount to be supplied to the internal combustion engine, using the engine rotation speed and the intake average pressure as parameters;
Engine control means for switching between the first map and the second map according to a load condition of the internal combustion engine, and controlling an operating state of the internal combustion engine with the fuel injection amount obtained at that time;
Comprising idle detection means for detecting the vicinity of the throttle valve fully closed;
The engine control means uses the second map when the idle detection means detects that the throttle valve is in the vicinity of the fully closed state as a load condition of the internal combustion engine, and the idle detection means fully sets the throttle valve to the throttle valve. A fuel injection control device for an internal combustion engine, characterized in that the fuel injection amount is calculated using the first map when it is detected that it is not close. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4 , wherein the internal combustion engine is a single cylinder or a multi-cylinder composed of independent intake air.

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