JP2678756B2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and more particularly to the output timing of a drive pulse signal to a fuel injection valve provided for each cylinder in the engine operating state. The present invention relates to an electronically controlled fuel injection device configured to be switched according to the above. <Prior Art> Conventionally, as a system in which a fuel injection valve is provided for each cylinder of an engine to inject and supply fuel, for example, sequential injection (sequential injection) described in JP-A-57-8328 is disclosed. There is a method. This sequential injection system is one in which fuel is injected and supplied from a fuel injection valve in time with the intake stroke of each cylinder, and it is possible to supply each cylinder with a mixture of fuel and air. The advantages are that there is little variation in combustion between cylinders, and torque fluctuations are small. By the way, when the fuel is injected by the sequential injection method at the time of starting the engine, the injection is started after the cylinder discrimination is completed and the startability deteriorates. ,
There is a system in which fuel is supplied by an all-cylinder simultaneous injection system in which fuel is simultaneously injected and supplied from fuel injection valves of all cylinders, and after the start is completed, the all-cylinder simultaneous injection system is switched to a sequential injection system. <Problems to be Solved by the Invention> By the way, when switching from the simultaneous injection method to all cylinders to the sequential injection method as described above, in order to avoid over-riching of the air-fuel ratio at the time of transition to the sequential injection method. In the case of a four-cylinder internal combustion engine, for example, in the case of a four-cylinder internal combustion engine, it is determined that the engine should be switched to sequential injection after the fuel injected at the end of simultaneous injection of all cylinders is sucked into each cylinder. Sequential injection was started after rotating twice. As a result, although the air-fuel ratio can be prevented from becoming over-rich, there is a problem that cylinders in which the air-fuel ratio becomes over lean are generated.
As in the case of No. -148034, by performing group injection when switching the injection method, it is possible to solve the above problems. However, in order to satisfactorily suppress the air-fuel ratio fluctuations of all the cylinders, a large number of cylinder groups (corresponding to which intake stroke of the cylinders the simultaneous injection is synchronized with) are switched according to the switching timing from the all-cylinder simultaneous injection method. It is necessary to perform group injection by properly using four types of cylinders (four types). That is, depending on which cylinder has the same timing as the intake stroke at the end of the simultaneous injection of all cylinders, for example, a cylinder in which the intake stroke reaches the intake stroke by the start of sequential injection after two revolutions in four cylinders and the air-fuel ratio becomes over lean And determine
It is necessary to perform group injection for such a group of cylinders (4 types of 4 cylinders), which results in the use of a large number of cylinder groups, resulting in an increase in memory capacity and computation time. The problem occurs. The present invention has been made in view of the above problems, configured to perform group injection at the time of switching from the all-cylinder simultaneous injection method to the sequential injection method, and reduce the type of cylinder group in the group injection, An object of the present invention is to provide an electronically controlled fuel injection device that can suppress fluctuations in the air-fuel ratio. <Means for Solving Problems> Therefore, in the present invention, as shown in FIG. 1, the fuel injection amount is set according to the engine operating state, and the driving of the pulse width corresponding to the set fuel injection amount is performed. An electronic engine of an internal combustion engine configured to output a pulse signal to a fuel injection valve provided for each cylinder of the engine at a predetermined timing in synchronization with engine rotation to drive the fuel injection valve and inject fuel to the engine. In a controlled fuel injection device, all-cylinder simultaneous injection control means for simultaneously outputting the drive pulse signal to all the fuel injection valves of all cylinders, and sequential injection for outputting the drive pulse signal at the respective timings of the intake strokes of the respective cylinders. A control means, a group injection control means for outputting the drive pulse signal for each predetermined cylinder group, and a sequential injection control means for all cylinders Injection control means detects a predetermined switching operation state and outputs a switching request signal, and the all-cylinder simultaneous injection control means drives when the switching operation state detection means outputs the switching request signal. Until the simultaneous injection of all cylinders is performed at the timing synchronized with the intake stroke of the specific cylinder among the plurality of cylinders with the intake stroke synchronized with the output timing of the pulse signal, the operation of the all-cylinder simultaneous injection control means is continued, and thereafter. An injection switching control unit that causes the group injection control unit to output a drive pulse signal to a predetermined cylinder group corresponding to the specific cylinder, and then switches to the sequential injection control unit is provided. <Operation> According to the electronically controlled fuel injection device having such a configuration, the switching operation state from the fuel injection control by the all-cylinder simultaneous injection control means to the sequential injection control means is detected by the switching operation state detection means, and the switching request signal is output. However, all cylinders simultaneous injection is continued until all cylinders simultaneous injection is performed at the timing synchronized with the intake stroke of the specific cylinder,
When the simultaneous injection of all cylinders is performed at a timing synchronized with the intake stroke of the specific cylinder, group injection is performed on a predetermined cylinder group corresponding to the specific cylinder, and then the sequential injection is switched to. That is, even if the switching operation state detecting means detects the switching operation state to the sequential injection control means, it does not always immediately shift to the group injection, but the timing of simultaneous injection of all cylinders when the switching operation state is detected is preset. When it matches the optimum timing of group injection to the specified cylinder group (the timing at which the air-fuel ratio over lean of each cylinder can be avoided), it immediately shifts to group injection, but it becomes over lean by fuel injection to a predetermined cylinder group. When it is not possible to avoid the above, the simultaneous injection of all cylinders is continued to match the optimum injection timing for the predetermined cylinder group. Therefore, it is not necessary to preset a cylinder group that can handle all of the injection timings in all-cylinder simultaneous injection, and with a smaller number of types than this cylinder group, avoiding over leaning of the air-fuel ratio at the time of sequential injection transition. It is possible. <Example> An example of the present invention will be described below with reference to the drawings. In FIG. 2, the 4-cylinder internal combustion engine 1 has an air cleaner.
Air is sucked through the intake duct 3, the throttle chamber 4, the intake manifold 5, and the intake valve 6. The throttle chamber 4 is provided with a throttle valve 7 interlocked with an accelerator pedal (not shown), and controls the intake air flow rate Q. The intake manifold 5 (or intake port) is provided with a fuel injection valve 8 for each cylinder. This fuel injection valve 8
Is an electromagnetic fuel injection valve that energizes the solenoid to open the valve and deactivates the valve to close the valve. The solenoid is energized by the drive pulse signal from the control unit 9 to open the valve, and the pressure is fed from a fuel pump (not shown). The fuel regulated to a predetermined pressure by the pressure regulator is supplied to the engine 1
To be injected. The control unit 9 receives output signals from various sensors, performs arithmetic processing as will be described later by a built-in microcomputer, determines a fuel injection amount (injection time) Ti and an injection timing (injection method), and drives pulses according to these. A signal is output to the fuel injection valve 8. That is, in this embodiment, the control unit 9
Serves also as the sequential injection control means, the group injection control means, the all-cylinder simultaneous injection control means, and the injection switching control means. As the various sensors, a hot-wire type air flow meter 10 is provided in the intake duct 3, and the intake air flow rate Q
The signal corresponding to is output. Further, a crank angle sensor 11 is built in a distributor (not shown) and outputs a reference signal for each 90 ° crank angle and a cylinder discrimination signal for each 180 ° (a cylinder number is indicated by the number of pulses). . Here, the rotation speed N of the engine 1 can be detected by measuring the cycle of the reference signal. Further, a potentiometer type throttle sensor 12 is provided on the throttle valve 7 and outputs a signal according to the opening α of the throttle valve 7. Further, a water temperature sensor 13 is provided in the water jacket of the engine 1 to cool the cooling water temperature.
Output the signal according to Tw. Further, the control unit 9 uses the ignition key switch 15 as the operating power source and the voltage of the battery 14 for detecting the power source voltage VB.
Is applied via the starter switch 16
OFF signal is input. In the present embodiment, the engine operating state for calculating the fuel injection amount Ti is the intake air flow rate Q, the engine speed N, the throttle valve opening α, the cooling water temperature Tw and the battery voltage detected by the above-mentioned sensors. VB is equivalent. Next, the fuel injection control by the microcomputer in the control unit 9 will be described according to the injection control method switching routine and the fuel injection amount setting routine shown in the flowcharts of FIGS. 3 and 4. The injection control system switching routine shown in the flow chart of FIG. 3 is executed every time the crank angle sensor 11 outputs the reference signal twice (every 180 °), and the step (denoted as S in the figure, The same applies hereinafter) 1,
It is determined whether or not the current engine operating state is an operating state in which simultaneous injection of all cylinders is required. The engine operating state in which simultaneous injection of all cylinders is required is, for example, a starter switch.
16 is ON and the starter motor is in an engine starting state, in which case the starter switch 16 corresponds to the switching operation state detecting means, and the starter switch 16 is ON.
→ OFF switching corresponds to the switching request signal for simultaneous injection from all cylinders to sequential injection. When it is determined in step 1 that all cylinders simultaneous injection is required (for example, when the starter switch 16 is ON), the process proceeds to step 2 and the engine 1 has made one revolution from the previous all cylinders simultaneous injection. If it is determined that one revolution has been performed, the routine proceeds to step 3 where the drive pulse signals are simultaneously output to the fuel injection valves 8 of all cylinders (all four cylinders) to perform fuel injection. Here, the pulse width of the drive pulse signal corresponds to the fuel injection amount Ti set in the flowchart of FIG. On the other hand, in step 2, the engine 1 from the previous simultaneous injection of all cylinders
If it is determined that the engine has not made one revolution, the routine is terminated and fuel injection is not performed. That is, when simultaneous injection is required for all cylinders, each revolution of the engine 1 (36
Fuel injection is performed simultaneously for all cylinders every 0 ° rotation. Further, when it is determined in step 1 that all cylinders simultaneous injection is not required (for example, the starter switch 16 is turned off).
If so), the routine proceeds to step 4, where it is determined whether group injection has been executed after the simultaneous injection of all cylinders has been stopped. In the present embodiment, the simultaneous injection from all cylinders is performed once and then the group injection is performed, and then the sequential injection is performed. Therefore, if it is determined that the group injection is being performed, the process proceeds to step 12 to perform the sequential injection. Inject. The sequential injection is set in the flowchart of FIG. 4 so that the cylinder in the intake stroke at that time is determined based on the cylinder determination signal from the crank angle sensor 11 and the fuel injection is ended when the intake valve 6 is opened. A drive pulse signal having a pulse width corresponding to the fuel injection amount Ti is output to the fuel injection valve 8 of the cylinder. On the other hand, when it is determined in step 4 that the group injection is not executed, that is, the operation state where the simultaneous injection of all cylinders is not required but the sequential injection control is to be performed, the group injection is still executed. If not, the routine proceeds to step 5, where the injection timing in simultaneous injection for all cylinders is determined. Since the all-cylinder simultaneous injection is performed based on the reference signal from the crank angle sensor 11, even if the injection is performed every one rotation of the engine 1, the injection timing is as shown in FIG.
When synchronized with the intake stroke of the 1st and 2nd cylinders (#
There are two types (pattern I or pattern II), i.e., in the case of synchronizing with the cylinder discrimination signal of the 1st cylinder and the # 2 cylinder) and in the case of synchronizing with the intake stroke of the # 3 cylinder and the # 4 cylinder. If it is determined in step 5 that the simultaneous injection timings of all cylinders are in synchronization with the intake strokes of the # 1 cylinder and # 2 cylinder (pattern I in FIG. 5), the process proceeds to step 6 and the current (recent) Whether the cylinder discrimination signal corresponds to # 1 cylinder or # 2 cylinder (intake stroke timing of # 2 cylinder or # 1 cylinder), or # 3 cylinder or # 4
It is determined whether it corresponds to a cylinder. Here, the cylinder discrimination signal this time is # 3 cylinder or # 4.
When it corresponds to a cylinder, it means that the timing is 180 ° earlier than the injection timing of all-cylinder simultaneous injection. Therefore, this routine is ended and fuel injection is not performed. That is, in this embodiment, the group injection is performed after 360 ° rotation (one rotation) from the end of the simultaneous injection of all cylinders, and the sequential injection is started after further 360 ° rotation (one rotation). Therefore, when it is determined in step 6 that the cylinder discrimination signal this time corresponds to the # 3 cylinder or the # 4 cylinder, the cylinder discrimination signal is the # 1 cylinder or 360 ° when all cylinders are simultaneously injected. Since it should correspond to the # 2 cylinder, fuel injection is not performed when the cylinder discrimination signal this time corresponds to the # 3 cylinder or the # 4 cylinder. If it is determined in step 6 that the cylinder discrimination signal this time corresponds to the # 1 cylinder or # 2 cylinder,
Since it is the state that 360 ° rotation (1 rotation) from all cylinders simultaneous injection, proceed to step 7 and the cylinder discrimination signal this time is # 1.
It is determined whether the cylinder corresponds to the cylinder or the # 2 cylinder. Here, when it is determined that the cylinder discrimination signal of this time corresponds to the # 1 cylinder (intake stroke timing of the # 2 cylinder as the specific cylinder), the process proceeds to step 3 and all cylinders are simultaneously injected as in the previous time. To perform. In this embodiment, the timing of simultaneous injection in all cylinders is # 1 cylinder or #
When synchronized with the intake stroke of the two cylinders, it is desired to perform group injection for the # 1 cylinder and the # 3 cylinder as shown in the pattern (I) of FIG. 5, but the cylinder discrimination signal this time is # 1.
If the group injection is executed for the # 1 cylinder and the # 3 cylinder when it corresponds to the cylinder, the air-fuel ratio of the # 1 cylinder and the # 3 cylinder becomes overrich. In order to avoid this, it is necessary to inject the # 2 cylinder and the # 4 cylinder as a group, but in this case, it is necessary to prepare four types of cylinder groups including the case of the pattern (II). For this reason, in the present embodiment, the group injection is performed on the # 1 cylinder and the # 3 cylinder to continue simultaneous injection for all cylinders until the air-fuel ratio of each cylinder can be controlled well. When it is determined in step 7 that the cylinder discrimination signal this time is equivalent to the # 1 cylinder, the process proceeds to step 3 and when the simultaneous injection of all cylinders is executed, the cylinder discrimination signal after one rotation from this simultaneous injection of all cylinders is equivalent to the # 2 cylinder. Therefore, the group injection timing is such that the air-fuel ratio can be optimally controlled by executing the group injection for the # 1 cylinder and the # 3 cylinder by continuing the simultaneous injection of all cylinders only once. is there. On the other hand, when it is determined in step 7 that the cylinder discrimination signal this time is equivalent to the # 2 cylinder, the process proceeds to step 8 without continuing the all-cylinder simultaneous injection control, and for the # 1 cylinder and the # 3 cylinder, Group injection,
It is possible to prevent the air-fuel ratios of the # 1 cylinder and the # 3 cylinder from becoming over lean. On the other hand, in step 5, the timing of simultaneous injection in all cylinders is #
When it is determined that the intake strokes of the 3rd cylinder and the # 4 cylinder are synchronized (synchronized with the # 3 cylinder and the # 4 cylinder of the cylinder discrimination signal), the synchronization of the # 1 cylinder or the # 2 cylinder described above is performed. Similar to the case of injection, the group injection timing is when the cylinder discrimination signal corresponds to # 3 cylinder or # 4 cylinder, but in this case, group injection is desired to be performed only on # 2 cylinder and # 3 cylinder. If the group injection is executed only when the cylinder discrimination signal corresponding to four cylinders is output, and if the group injection is performed for # 2 cylinder and # 3 cylinder when the cylinder discrimination signal corresponding to # 3 cylinder is output, the air-fuel ratio becomes Since the fuel is overrich, the routine proceeds to step 3 and the simultaneous injection for all cylinders is continued (steps 9 to 10). In this way, when transitioning from simultaneous injection to all cylinders to sequential injection, group injection is performed so that over leaning of the air-fuel ratio of each cylinder can be avoided. 2 types (# 1and
Only in # 3, # 2 and # 3), all cylinders simultaneous injection is continued until it becomes possible to avoid over leaning of the air-fuel ratio by group injection by some cylinder group. Therefore, originally, in order to avoid making the air-fuel ratio lean of each cylinder when switching the injection method,
Although it is necessary to selectively use different types of cylinder groups, in the present embodiment, only two types of cylinder groups are required as described above, and it is possible to save the memory capacity and shorten the calculation time. FIG. 4 is a fuel injection amount setting routine in which the fuel injection amount Ti corresponding to all cylinders simultaneous injection, group injection and sequential injection is set. In step 21, information on the engine operating state detected by each sensor is input. In step 22, the basic fuel injection amount Tp (= K × Q / N; K is a constant) is calculated based on the intake air flow rate Q and the engine rotation speed N. In step 23, the coolant temperature Tw that represents the engine temperature
Also, various correction factors COEF are set by the throttle valve opening α, which indicates acceleration / deceleration operation and idle operation of the engine 1. In step 24, the effective injection amount Te (= Tp × COEF) is calculated by the basic fuel injection amount Tp calculated in step 22 and the various correction coefficients COEF set in step 23. In step 25, the voltage correction amount Ts is set by the voltage VB of the battery 14. This voltage correction component Ts is the battery voltage
This is for correcting the change in the effective valve opening time of the fuel injection valve 8 due to the change in VB. In step 26, it is determined whether the current injection method is sequential injection, simultaneous injection in all cylinders or group injection, and if it is sequential injection, Ti =
The fuel injection amount Ti is set as 2Te + Ts. On the other hand, when all-cylinder simultaneous injection or group injection is used, Ti = Te +
The fuel injection amount Ti is set as Ts. In the case of simultaneous injection in all cylinders, the injected fuel for two injections is sucked into one cylinder in the intake stroke, so as described above, half the effective injection amount Te used in sequential injection is used. Also in the group injection, the fuel injection amount Ti = Te + Ts at the time of simultaneous injection of all cylinders is used to avoid the lean air-fuel ratio before the sequential injection is started. Although the four-cylinder internal combustion engine has been described in the present embodiment, even if the internal combustion engine has a larger number of cylinders than four cylinders, the lean air-fuel ratio at the time of switching the injection system can be similarly avoided, and It is clear that the number of cylinder groups can be reduced. <Effects of the Invention> As described above, according to the present invention, by performing group injection when switching from simultaneous injection to all cylinders to sequential injection, the air-fuel ratio of each cylinder can be satisfactorily controlled and the optimum cylinder group can be optimized. Since the simultaneous injection of all cylinders is continued until the injection timing comes, it is possible to reduce the number of cylinder groups in the group injection, and it is possible to save the memory capacity and shorten the calculation time. is there.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a functional block diagram showing a configuration of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the present invention, and FIG. 3 is an injection control system switching routine in the same embodiment. 4 is a flowchart showing a fuel injection amount setting routine in the above embodiment, and FIG. 5 is a time chart for explaining the timing of switching the injection method in the above embodiment. 1 ... Engine, 8 ... Fuel injection valve, 9 ... Control unit, 10 ... Air flow meter, 11 ... Crank angle sensor, 12 ... Throttle sensor, 13 ... Water temperature sensor, 14
…… Battery, 16 …… Starter switch

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Seiichi Otani               Gunma Prefecture Isesaki City Kasukawa Town 1671-1 Japan               Electronic Equipment Co., Ltd.                (56) References JP-A-60-1349 (JP, A)                 JP-A-59-18248 (JP, A)                 JP-A-60-237138 (JP, A)                 JP 57-8328 (JP, A)                 JP 60-116841 (JP, A)                 JP 63-314351 (JP, A)

Claims (1)

(57) [Claims] A fuel injection amount is set according to the engine operating state, and a drive pulse signal having a pulse width corresponding to the set fuel injection amount is given to a fuel injection valve provided for each cylinder of the engine at a predetermined timing synchronized with the engine rotation. In an electronically controlled fuel injection device for an internal combustion engine configured to drive the fuel injection valve to inject fuel into the engine by supplying the drive pulse signal to all the fuel injection valves of all cylinders at the same time. Cylinder simultaneous injection control means, sequential injection control means for outputting the drive pulse signal in time with the intake stroke of each cylinder, and group injection control means for outputting the drive pulse signal for each predetermined cylinder group And a predetermined switching operation state from the all-cylinder simultaneous injection control means to the sequential injection control means is detected, and a switching request signal is output. Of the plurality of cylinders whose intake stroke is synchronized with the output timing of the drive pulse signal by the all-cylinder simultaneous injection control means when a switching request signal is output from the switching operation state detection means. Until all cylinders simultaneous injection is performed at a timing synchronized with the intake stroke of the specific cylinder, the operation of the all cylinders simultaneous injection control means is continued, and thereafter, a predetermined cylinder group corresponding to the specific cylinders. To the group injection control means, and further after that, injection switching control means for switching to the sequential injection control means, and an electronically controlled fuel injection device for an internal combustion engine.