JPS61201854A - Control device for injection timing of internal-combustion engine - Google Patents

Abstract

PURPOSE:To enable injection of fuel at an optimum fuel injection timing responding to an operating condition, by a method wherein a fuel injection timing is set through selection of a fuel injection time setting value computing condition responding to plural operating conditions. CONSTITUTION:Map, calculating a fuel injection timing responding to each case of various operating conditions of a 4-cylinder engine 1, e.g., a lean feedback control range, a power range, an open range, is stored to the interior of an ECU 10 and an ROM 10b. With the nnumber of revolutions of an engine, detected by a rotary angle sensor AS1, and a pressure in a suction pipe, measured by a sensor PS1 for a pressure in a suction pipe, forming a variable, a fuel injection tiing is represented by means of a crank angle from a top dead center. Map corresponding to a given condition responding to each operationg condition is selected, and based on the map, the fuel injection timing is calculated from the number of revolutions of an engine and the pressure in the suction pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to a fuel injection timing control device for an internal combustion engine, and particularly to a fuel injection timing control device for an internal combustion engine that controls the air-fuel ratio by changing the air-fuel ratio according to various operating conditions. Regarding a control device.

[Prior Art 1] Conventionally, an independent injection method has been adopted in which fuel injection is performed by opening and closing a fuel injection valve for each cylinder in accordance with the intake stroke of each cylinder of an internal combustion engine. In this type of system, fuel injection is performed in each cylinder in accordance with the intake stroke, so it not only provides excellent operational performance such as transient characteristics of the internal combustion engine, but also enables combustion control at a so-called lean air-fuel ratio. It had the advantage of being possible.

Regarding the so-called lean burn control type internal combustion engine as described above, a fuel injection timing control device for the internal combustion engine has been proposed that reduces harmful components of exhaust gas and improves drivability.

In the lean burn control method described above, when the fuel injection timing is set to the advance side of the crank angle after top dead center, the harmful component NOx in the exhaust gas is reduced. On the other hand, in order to suppress torque fluctuations of the internal combustion engine to below a predetermined value, it is necessary to set the fuel injection timing to the crank angle retard side after top dead center. For this reason, Moe! -4 Injection brightness has a certain range due to the relationship between the above characteristics.

[Problems to be Solved by the Invention] Incidentally, in an internal combustion engine using a system that controls the air-fuel ratio, such as the lean burn control system described above, fuel injection timing is an important factor regarding the performance of the internal combustion engine. In internal combustion engines using the lean burn control system as described above, the fuel injection timing is generally set to be optimal for the lean burn range (lean feedback control state), so it is not possible to maintain a state where a large load is constantly applied, the so-called "lean feedback control state". power range, or the state where air-fuel ratio feedback control is not performed when the oxygen concentration sensor is not activated, the so-called open range, and the operating state such as when the engine is warmed up or when the vehicle is accelerating. When the internal combustion engine is operated in a state other than the lean burn range, the fuel injection timing may not be at the optimum value, which may lead to a decrease in drivability and fuel efficiency.

[Means for Solving the Problems] Means for solving the above problems will be explained based on FIG. 1. FIG. 1 is a block diagram showing the basic concept of the present invention. As shown in FIG. 1, the present invention provides a fuel injection timing control device for an internal combustion engine that independently injects fuel to the cylinders of the internal combustion engine a so as to switch the air-fuel ratio according to the operating state of the internal combustion engine a. The operating state detecting means detects the operating state including the load and rotational speed of the internal combustion engine a, and detects the load, the rotational speed, and the fuel injection timing of the internal combustion engine a, each corresponding to a plurality of operating conditions of the internal combustion engine a. The fuel injection timing is determined from the calculation condition storage means C based on the detection results obtained from the calculation condition storage means C having the fuel injection timing set value calculation conditions that define the relationship between the fuel injection timing setting value and the operation state detection means. A selection means d for selecting a set value calculation condition and a load and rotational speed of the internal combustion engine a determined by the operating state detection means 11 using the fuel injection timing set value calculation condition selected by the selection means d. a fuel injection timing setting means e for setting the fuel injection timing based on the fuel injection timing; and a control means f for independently injecting fuel for each cylinder of the internal combustion engine according to the fuel injection timing obtained from the fuel injection timing setting means e. The gist of the present invention is a fuel injection timing control device for an internal combustion engine.

Here, the operating state detection means is, for example, the internal combustion engine a.
In addition to the load and rotation speed, the system detects the intake air temperature, cooling water temperature, throttle valve opening, exhaust temperature, and oxygen concentration in the exhaust gas.

Further, the fuel injection timing setting value calculation condition may be, for example, a two-dimensional map expressing the fuel injection timing setting value using the load and rotation speed of the internal combustion engine a as both coordinate axes, and the fuel injection timing setting The value calculation condition may be, for example, a calculation formula that expresses the fuel injection timing setting value using the load and rotational speed of the internal combustion engine a as variables.

[Effect] Next, the operation of the present invention will be explained based on FIG.

While the internal combustion engine a is in operation, the operating state detection means detects the load, rotation speed, and operating state of the internal combustion engine a.

Then, the selection means d selects one fuel injection timing setting value calculation condition from the calculation condition storage means C based on the detection result of the driving state detection means.

Next, the fuel injection timing setting means e sets the fuel injection timing based on the fuel injection timing setting value calculation condition selected by the selection means d, using the detection result of the driving state detection means.

Roughly, the control means f performs fuel injection according to the fuel injection timing set by the fuel injection timing setting means e.

The technical problems of the present invention are solved as described above.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail based on the drawings.

FIG. 2 is a system configuration diagram of a four-cylinder engine equipped with the fuel injection timing control device for an internal combustion engine according to the present invention.

In the figure, 1 is a four-cylinder engine, 1a is the cylinder of one cylinder, 1b is the piston of the cylinder, 1G is the spark plug, 1d is the intake pipe, 1e is the surge tank that absorbs the pulsation of intake air, and SVl is the throttle valve, 1f
is an air cleaner, 1Q is an exhaust manifold, IG is an igniter that outputs the high voltage necessary for ignition, and 1h is a crankshaft (not shown) that connects and transfers the high voltage generated by the above igniter ■G to each cylinder's spark plug 1C. Each represents a distributor that distributes and supplies.

ATSl is an intake air temperature sensor installed in the air cleaner 1f and detects the temperature of the intake air sent to the four-cylinder engine 1; WTSl is a water temperature sensor installed in the cooling system of the four-cylinder engine 1 that detects the cooling water temperature; 5PS1 is a throttle position sensor that detects the opening degree of the throttle valve SVI in conjunction with the throttle valve SV1 and outputs a signal, and PSl is the intake pipe internal pressure pm of the intake pipe 1d.
LMS is an oxygen concentration sensor (lean mixture sensor) that is installed in exhaust manifold 1q and outputs the residual oxygen concentration in exhaust gas as an analog signal, and ETSL is also installed in exhaust manifold 1.
1 and 2 respectively represent exhaust temperature sensors that are provided in g and detect the temperature of exhaust gas.

In addition, the ASI is installed inside the distributor 1h, and the camshaft of the distributor 1h is connected to the ASI.
C31 is a rotation angle sensor that also serves as a rotation speed sensor that outputs a rotation angle signal every 24 rotations, that is, every integer multiple of the crank angle O0 to 30', and C31 is the same as the distributor 1 described above.
h, and for each point of the camshaft of the distributor 1[), that is, 2 of the crankshaft (not shown).
a cylinder discrimination sensor that outputs a reference signal once at each rotation point; and 10, an electronic control device (hereinafter simply E
It's called CU. ).

Next, the configuration of the ECLJ 10 is shown in FIG.

10a is a central processing unit (hereinafter simply referred to as CPU) that inputs and calculates the data output from each of the above-mentioned sensors according to a control program and performs processing for controlling the operation of various devices; Read-only memory (hereinafter simply referred to as ROM) in which data is stored, 10C
10d is a random access memory (hereinafter simply referred to as RAM) in which data input to the ECUIO and data necessary for arithmetic control are temporarily read/written; Backup random access memory (hereinafter simply referred to as backup RAM) backed up by a battery to hold data necessary for control of the 10k, 10Ω, 10
m110n, 10D, and 10q are buffers for the output signals of the intake pipe pressure sensor PS1, throttle position sensor 5PSI, water temperature sensor WTS1, intake temperature sensor ATSI, exhaust temperature sensor ETS1, and oxygen concentration sensor (lean mixture sensor) LMS, respectively, and 10j is the above A multiplexer that selectively outputs the output signal of each sensor to the CPU 10a, 10i an A/D converter that converts an analog signal into a digital signal, and 10r a waveform of each output signal of the cylinder discrimination sensor C81 and the rotation angle sensor AS1. 10e represents a shaping circuit for shaping, and 10e is a shaping circuit 10r.

Or buffer 10k, 10Q, 10m, 10n, 1
0p, 10Q,? Each sensor signal is sent to the CPU 10a via the Lunaplexer 10j1 and the A/D converter 101, and the multiplexers 10j and A from the CPU 10a are
It represents an input/output port that outputs a control signal to the /D converter 101.

And 10S and 10t connect to CP via output port 10f.
Each of the diagrams represents a drive circuit that applies a drive current to the fuel injection valve INJ and igniter IG in response to a control signal from tJloa. In addition, 10Q is a path line for control signals and data, and 10h is a ROM including CPtJloa.
10b, RAM 10c, etc. at predetermined intervals. The output boat 10f is equipped with a counter for setting the fuel injection amount (fuel injection time).
When the fuel injection start process is performed by PLJloa,
Only for the time corresponding to the value set in the above counter in advance,
It is possible to control the opening of the fuel injection valve INJ.

Next, FIG. 4 shows the processing executed by the ECU 10.
This will be explained using flowcharts shown in FIGS. 5 and 6. Note that the three-digit number in parentheses represents the step number of each process.

FIG. 4 shows the main control program for the four-cylinder engine 1 executed by the ECU 10, FIG. 5 shows the first interrupt program for setting fuel injection timing, and FIG. 6 shows the second interrupt program for performing fuel injection. . Note that each of the above-mentioned processes is repeatedly executed at predetermined time intervals.

Next, details of the main control program shown in FIG. 4 will be explained.

First, it is determined whether this process is the first process after starting the ECU 10 (100). If this processing is the first processing, initialization processing is performed (102>. In other words,
Memory clear, flag reset, and timer reset are performed. After the initialization process (102> or this process is 2)
If it is the first time or later, the process advances to step 104. Here, the rotational speed Ne of the four-cylinder engine 1 is measured by the rotation angle sensor ASI, and the intake pipe pressure Pm is measured by the intake pipe pressure sensor P.
From S1, a process is performed in which the intake air temperature Ta is detected by the intake air temperature sensor ATS1 (104).

Here, the engine rotation speed Ne is the interval of the signal transmitted by the rotation angle sensor AS1 every 30 degrees of the crank angle.
c and is calculated from its reciprocal. Next, the process proceeds to step 106, in which the intake air amount is calculated from the intake pipe internal pressure Pm and the intake air temperature Ta detected in the step 104, and the intake air amount is divided by the engine rotational speed Ne to calculate the intake air amount per cylinder. The basic fuel injection time τp is calculated by calculating the fuel injection value. Next, the process proceeds to step 108, in which R
The basic advance angle of the ignition timing is read out from the map stored in the OM 10b, and the basic ignition timing θp is calculated. Next, the air-fuel ratio feedback signal @LS is detected by the oxygen concentration sensor (lean mixture sensor) LMS, the water temperature TW is detected by the water temperature sensor WTS1, the throttle position Sp is detected by the throttle position sensor 5PSI, and the exhaust temperature Te is detected by the exhaust temperature sensor ETS1. (1)
10). Next, the air-fuel ratio feedback correction coefficient, warm-up increase coefficient, acceleration increase coefficient, high load increase coefficient, etc. are calculated from the air-fuel ratio feedback signal LS, water temperature TW, and throttle position Sp detected in step 110, and the fuel The injection tolerance correction term C is calculated (112). Next, an ignition timing correction term K is calculated by calculating a warm-up correction value, a high temperature correction value, etc. from the water ITw and exhaust gas ITe detected in step 110 (114>). The fuel injection time τO is calculated based on the basic fuel injection time τp obtained in step 112 and the fuel injection correction term C obtained in step 112 (116).Next, the basic ignition timing θp obtained in step 108 and the fuel injection correction term C obtained in step 112 are calculated (116). Ignition timing θ0 is calculated based on the ignition timing correction term obtained in (1
18).

Next, the process proceeds to step 120, where it is determined whether or not there is an ignition cylinder based on the outputs of the cylinder discrimination sensor C81 and the rotation angle sensor ASI. If this condition is met, the process proceeds to step 122, where the ECLIIO outputs a control signal from the output boat 10f based on the ignition timing θO calculated in step 118, and energizes the igniter IG using the drive circuit 10t. Ignition is performed by controlling the drive.

On the other hand, if the condition at step 120 is not met, this process ends. Thereafter, the above process is repeated.

Next, the details of the first interrupt program for setting the fuel injection timing will be explained based on FIG.

First, cylinder discrimination sensor C81 and rotation angle sensor AS1
It is determined from the output whether or not a crank angle of 180' has been detected (200>. If this condition is not met, this process ends and the process returns to the main control program described above. On the other hand, if the above condition is met) If so, the process proceeds to step 202. Here, whether or not the operating state of the four-cylinder engine 1 is under lean feedback control is detected based on the state of the lean feedback flag FLEB (202). Flag FLEB is 4
After starting the cylinder engine 1, it is set according to a predetermined program procedure. If this condition is met, the process proceeds to step 204, where a lean fuel injection timing map is selected, and then the process proceeds to step 212. Here, the lean fuel injection timing map, as shown in FIG.
The fuel injection timing in the lean feedback control region is expressed by the crank angle from top dead center using mmHCl1 as each variable.
b is stored internally. Furthermore, if the conditions in step 202 above are not met, the process proceeds to step 206.

Here, whether or not the operating state of the four-cylinder engine 1 is increasing power is detected based on the state of the power increase flag FPOW (206). Here, the power increase flag FPOW is set after being detected from the throttle position Sp or the intake pipe internal pressure pm. If this condition is met, proceed to step 210;
After selecting the power range fuel injection timing map, step 2
Proceed to step 12. Here, the power range fuel injection timing map is, as shown in FIG.
, mco and intake pipe pressure Pm [mmHg] are used as variables, and the fuel injection timing during power increase is expressed as a crank angle from top dead center.
This is stored inside the OM10b. In addition, if the conditions in step 206 above are not met, step 2
Proceed to 08.

Here, after selecting the open range fuel injection timing map, the process proceeds to step 212. Here, the open range fuel injection timing map, as shown in FIG.
The fuel injection timing in the open area is expressed by the crank angle from top dead center, with l as each variable,
This is stored in advance inside the ROM 10b of ECLJlo.

Next, the process proceeds to step 212, where the engine rotation speed Ne is detected. The process then proceeds to step 214, where the intake pipe internal pressure Pm is detected. Then, the process proceeds to step 216, and based on any one of the maps selected in steps 204, 208, and 210, the fuel injection timing corresponding to the engine rotational speed Ne and intake pipe pressure Pm detected in steps 212 and 214 is determined. This process is terminated by locking out Tinj and returning to the main control program. Note that the first interrupt program is repeatedly executed from now on as appropriate.

Next, the second interrupt program for performing fuel injection will be explained in detail based on FIG.

This program is activated without delay by a signal from the rotation angle sensor AS1 generated every 30 degrees of crank angle, and is executed by interrupting the above-mentioned main control program.

First, it is determined whether there is a cylinder that has reached top dead center at the beginning of intake at the crank angle at which the interruption occurred (300).
. This can be known from the output signal of the cylinder discrimination sensor C81 and the output signal of the rotation angle sensor AS1.
Every 0', one of the cylinders will undergo an intake stroke in which fuel injection should be performed. If the conditions in step 300 are not met, this process is terminated and the process returns to the main control program. On the other hand, if the above conditions are met, the fuel injection timer T1 counts up (3
02>. Next, the first one above! Read out the fuel injection timing T inj @ set by the IJ-included program and stored in a predetermined area of RAM10C, and set the fuel injection timing T in
It is determined whether or not time j has elapsed by comparison with the fuel injection timer T1 (304). Here, the fuel injection timing Tinj is expressed by the crank angle from the top dead center, but this value is converted into the time from the top dead center according to the rotation speed Ne of the four-cylinder engine 1, and the fuel injection timing Timer T1
It is compared with. If the amount of time that satisfies the conditions in step 304 has elapsed, the process proceeds to step 306. Here, a control signal is output to the output port 10f to start fuel injection. Based on this, in accordance with the fuel injection time τO that has already been set in the counter in the output port 10f by the main control program, the output port 10 A control signal is output from f,
The drive circuit 10S energizes the fuel injection valve INJ to drive and control the fuel injection valve INJ to open it. Next, the process proceeds to step 30B, where the fuel injection timer T1 is reset, this process is ended, and the process returns to the main control program again. Thereafter, the second interrupt program is executed at appropriate times.

In this embodiment, the internal combustion engine a includes a four-cylinder engine 1, an operating state detection means, or an intake pipe pressure sensor PS1.
and rotation angle sensor AS1 and throttle position sensor 5
PS1, water temperature sensor WTS1, intake temperature sensor ATS1, exhaust temperature sensor ETS1, oxygen concentration sensor (lean mixture sensor) LMS and ECLllo, numbing condition storage means C is stored in ROM 10b of ECUlo, and selection means d is executed by ECUlo. Processing (202, 204°2
06.208, 210>, the fuel injection timing setting means e sends the control means f to the process 216 executed by the ECUIO.
correspond to the processes (300, 302, 304, 306, 308) executed by the fuel injection valves INJ and ECUlo, respectively.

In this embodiment, there are maps for calculating the fuel injection timing according to various operating states of the four-cylinder engine 1, that is, lean feedback control range, power range, and open range, and the corresponding maps are selected. Then, based on the map, the engine speed Ne and the intake pipe pressure Pm are determined.
Since the fuel injection timing T inj@ is calculated, it is possible to set the optimum fuel injection timing according to various driving conditions.

Further, as described above, since fuel injection is performed at the optimal fuel injection timing according to various driving conditions, it is possible to improve drivability and fuel efficiency in each driving condition.

Although this embodiment has been described with respect to a four-cylinder engine 1 using a lean burn control method, the effects of the present invention can also be applied to an engine other than a lean burn method in which the air-fuel ratio changes depending on the operating state. It is something that occurs.

Furthermore, in this embodiment, a two-dimensional map with the engine rotational speed Ne of the four-cylinder engine 1 and the intake pipe internal pressure Pm as both coordinate axes was adopted as a means for setting the fuel injection timing.
For example, if the engine speed Ne and the intake pipe pressure pm are set to 2
The effects of the present invention can also be obtained even if an arithmetic expression for calculating the fuel injection timing is used as a variable.

Generally speaking, in this embodiment, the intake pipe internal pressure was used to detect the load of the four-cylinder engine 1, but other means may also be used as long as they represent the amount of intake air per intake stroke. The invention is effective.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention. .

[Effects of the Invention] As detailed above, according to the present invention, fuel injection timing setting value calculation conditions corresponding to a plurality of operating conditions are selected in accordance with the operating conditions to set the fuel injection timing. , it becomes possible to perform fuel injection at the optimal fuel injection timing according to various operating conditions.

Moreover, along with the above effects, it is possible to improve the operating performance and fuel efficiency of the internal combustion engine under various operating conditions.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the basic concept of the present invention, Fig. 2 is a system block diagram showing an embodiment of the present invention, and Fig. 3 explains the electronic control unit (ECU) used in the embodiment of the present invention. 4 is a flowchart showing the main control program executed by the ECU, and FIG. 5 is a block diagram showing the main control program executed by the ECU.
FIG. 6 is a flowchart showing the first interrupt program executed by the ECU, FIG. 7 is a flowchart showing the second interrupt program executed by the ECU, and FIG. 7 is a flowchart showing the second interrupt program executed by the ECU. Figure 8 is a graph showing a map for calculating the fuel injection timing in the power range from the load and rotation speed of the internal combustion engine, and Figure 9 is a graph showing the map for calculating the fuel injection timing in the power range from the load and rotation speed of the internal combustion engine. It is a graph showing a map for calculating fuel injection timing in an open area. a... Internal combustion engine b... Operating state detection means C... Calculation condition storage means d... Selection means e... Fuel injection timing setting means f... Control means 1... Four-cylinder engine 10...Electronic control unit (ECU) INJ...Fuel injection valve PSl...Intake pipe pressure sensor WTSI...Water temperature sensor 5PS1...Throttle position sensor AS1...
・Rotation angle sensor ATSl...Intake temperature sensor ETSI...Exhaust temperature sensor LMS...Oxygen concentration sensor (lean mixture sensor)

Claims (1)

[Scope of Claims] 1. A fuel injection timing control device for an internal combustion engine that injects and supplies fuel independently to each cylinder of the internal combustion engine so as to switch the air-fuel ratio according to the operating state of the internal combustion engine, which controls the load and rotation of the internal combustion engine. and a fuel injection system that defines a relationship among the load, rotational speed, and fuel injection timing of the internal combustion engine, each corresponding to a plurality of operating conditions of the internal combustion engine. a calculation condition storage means having a timing setting value calculation condition; a selection means for selecting a fuel injection timing setting value calculation condition from the calculation condition storage means based on the detection result obtained from the operating state detection means; a fuel injection timing setting means for setting a fuel injection timing based on the load and rotational speed of the internal combustion engine obtained from the operating state detection means using the selected fuel injection timing setting value calculation condition; A fuel injection timing control device for an internal combustion engine, comprising: control means for independently injecting fuel into each cylinder of the internal combustion engine according to the fuel injection timing obtained from the timing setting means. 2. Claim 1, wherein the operating state detection means detects intake air temperature, cooling water temperature, throttle valve opening, exhaust temperature, and oxygen concentration in exhaust gas in addition to the load and rotation speed of the internal combustion engine. The fuel injection timing control device for the internal combustion engine described above. 3. The internal combustion engine according to claim 1 or 2, wherein the fuel injection timing setting value calculation condition is a two-dimensional map representing the fuel injection timing setting value with the load and rotation speed of the internal combustion engine as both coordinate axes. Engine fuel injection timing control device. 4. The internal combustion engine according to claim 1 or 2, wherein the fuel injection timing setting value calculation means is an arithmetic expression that expresses the fuel injection timing setting value using the load and rotation speed of the internal combustion engine as variables. Fuel injection timing control device.