JPH02535B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling fuel increase in an electronically controlled internal combustion engine during and after starting.

[Conventional technology and its problems]

As is well known, in an electronically controlled internal combustion engine that uses a microcomputer etc. to adjust the opening time of the fuel injection valve (hereinafter simply referred to as the injection valve), it is necessary to increase the amount of fuel when starting the engine to maintain the engine's performance. A method of starting is adopted.

Conventionally, as a starting method of this type, a method is known in which the amount of fuel is increased while the starter switch is turned on. In this type of engine, as shown in FIG. 2, a starting flag is set to "1" while the starter switch is on, and while this flag is set to "1",
The opening time of the injection valve was set relatively long to increase the amount of fuel at startup. However, as shown in Figure 2, the starting flag is still set to "1" even after the engine speed has risen above the reference speed, which indicates that the engine has started successfully. The fuel consumption continues to increase, and as a result, fuel efficiency inevitably decreases. In addition, if the engine speed drops below the minimum reference speed that is a guideline for engine stall for some reason after starting (the starting flag is reset to "0"), at this point the starting increase is If this is not done, the engine speed may not increase and the engine may stall.

In order to solve the above-mentioned problems, various methods have been proposed for controlling the increase in fuel at the time of starting and for a certain period of time after starting. For example, a method for keeping the fuel injection amount constant when the engine speed drops below a predetermined set value after startup (Japanese Patent Application Laid-Open No. 147238/1983)
It has been known. In addition, a high level of fuel is increased at the time of startup, and the increase is gradually reduced after startup.If the engine speed drops below a certain standard after startup, the engine speed is There is a known method for increasing this (Japanese Unexamined Patent Publication No. 57-46031). These methods have the advantage of improving the startability of the engine, suppressing unnecessary increases in fuel consumption after starting, and saving fuel, as well as taking measures to prevent the engine speed from decreasing after starting. has.

However, if the engine speed decreases further, for example below 100 rpm, the engine will enter a transient state where the engine stalls, that is, it will transition from a complete explosion state to a state accompanied by a misfire, and the torque of self-powered rotation will be greatly reduced. Therefore, it is difficult to increase the engine speed by suppressing the degree of reduction in the fuel increase described above.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to start an engine smoothly, save fuel, and prevent engine stall.

[Means to solve the problem]

That is, the gist of the present invention is, as illustrated in the basic configuration diagram of FIG. and an electronic control circuit that receives detection signals from engine sensors including these various sensors and controls the opening and closing of the injection valves, and the starter switch detects that the engine is starting. (P1-YES), execute fuel increase processing to increase the fuel injection amount for starting (P5)
At the same time, it is determined that the engine speed has increased to a predetermined reference speed or higher based on the rotation speed signal from the rotation speed sensor (P2-YES);
Stop the fuel increase process for the above startup (P3)
In the fuel increase control method for an electronically controlled internal combustion engine, when the starter switch detects that the engine has started (P1-NO), the engine speed is
Determines that the rotation speed has fallen below a predetermined minimum reference rotation speed that is lower than the above reference rotation speed (P4-YES)
A fuel increase control method for an electronically controlled internal combustion engine is characterized in that the above-mentioned fuel increase process for starting is executed again (P5) to increase the fuel injection amount.

〔Example〕

This will be explained below with reference to the drawings.

FIG. 1 shows an example of an internal combustion engine system to which the present invention is applied.

In FIG. 1, 1 to 5 represent engine sensors. 1 is a rotation sensor, and the rotation sensor 1 is
For example, a rotation speed sensor is built into a distributor and generates a rotation speed signal in synchronization with the rotation of the engine's crankshaft, and the ignition of a reference cylinder among multiple cylinders such as a 4-cylinder engine or a 6-cylinder engine. and a cylinder discrimination sensor that detects the crank angle position corresponding to the timing. 2 is a starter switch, and the switch 2 detects when the starter switch is on, that is, when the engine is started. 3 is a digital sensor group other than the starter switch 2, and the digital sensor group 3 includes, for example, an O ₂ sensor that detects the residual oxygen concentration in the exhaust system, an air conditioner switch that detects whether the air conditioner is on or off, and the like. Reference numeral 4 denotes a cooling water temperature sensor, which is attached to, for example, a cylinder block and detects the cooling water temperature of the engine. Reference numeral 5 denotes a group of analog sensors other than the cooling water temperature sensor 4, and the analog sensor group 5 includes an air flow meter attached to the air supply system to detect the amount of intake air, an intake temperature sensor to detect the intake air temperature, and the like.

6 represents an electronic control circuit 6. The control circuit 6
, 7 is a microprocessor unit, that is, an MPU, and the MPU 7 controls the injection valves, which will be described later, based on various detection signals from the engine sensors 1 to 5, according to an engine control program written in advance in the ROM 8, which will be described later. Calculates valve opening time, etc. 8 is read-on memory, or ROM;
The ROM 8 stores engine control programs and the like in advance. Reference numeral 9 denotes a random access memory, or RAM, into which various data are temporarily written or read. A timer 10 generates a clock signal when starting timer interrupt processing, which will be described later. Reference numeral 11 denotes an interrupt input port to which the rotation speed signal from the rotation sensor 1 and the cylinder discrimination sensor signal are input as interrupt signals;
Outputs an interrupt command signal to MPU7. 12 is an input port into which a starter signal from the starter switch 2 and digital signals from other digital sensor group 3 are input; 13 is a cooling water temperature sensor 4;
The analog input port 13 is an analog input port into which the cooling water temperature signal from the
These analog signals are selectively converted into digital signals and output by a channel select signal from the MPU 7. 14 is a counter, which is set with numerical data corresponding to the opening time of the injection valve calculated by the MPU 7, and counts down the set numerical data in synchronization with the clock signal from the timer 10; For example, it continues to output a high level signal while counting down, and when the count ends, it inverts and outputs a low level signal. 15 is a power amplifying section, and the power amplifying section 15 performs power amplifying processing while the output signal of the counter 14 is at a high level, and selectively opens the electromagnetic injection valves 16-1 to 16-n. Outputs a command signal. 16-1 to 16-n represent electromagnetic injection valves installed in one-to-one correspondence with, for example, n cylinders. Further, CB represents a common bus for transferring data between the MPU 7 and other control circuit components 8 to 14.

FIG. 4 shows a first embodiment of the invention.

This first embodiment is executed by, for example, a 4 msec timer interrupt process. In this timer interrupt processing, immediately after the starter switch 2 is turned on, the engine speed is less than a predetermined reference speed, for example, 500 rpm, so the determination result in step 100 is "NO", and then step 101 is performed. is executed, and the determination result of step 101 is "YES" because it is immediately after the starter switch 2 is turned on, and then step 102 is executed.
is executed and the startup flag, that is, the STA flag, is "1"
is set to Here, the engine speed mentioned above is
In the MPU 7, the reference rotation speed is calculated based on the rotation speed signal from the rotation sensor 1, and the reference rotation speed is set as a guideline for determining whether the engine has been started satisfactorily. The determination (step 101) is made based on the start signal from the starter switch 2. The starting flag, or STA flag, is
This serves as an index for determining whether or not to execute a starting-time increase process for increasing the fuel injection amount for starting, which is separately executed in the electronic control circuit 6. Therefore, immediately after the starter switch 2 is turned on, the above-mentioned starting amount increase process is executed.
The opening time of the injection valves 16-1 to 16-n is set relatively long.

After that, when the engine speed increases and becomes equal to or higher than the reference speed, for example, 500 rpm, the determination result in step 100 becomes "YES", and a new step 103 is performed.
is executed, and the STA flag is reset to "0". Therefore, the above-mentioned start-up increase process is then stopped.

If the engine speed becomes equal to or higher than the reference speed while the starter switch 2 is in the ON state, the starting flag, ie, the STA flag, is reset and the starting fuel increase process is stopped. Therefore, fuel is saved while starting is performed well.

Thereafter, the route consisting of step 100 and step 103 is always selected until the starter switch 2 is turned off and the engine speed decreases for some reason and becomes less than the reference speed, for example, 500 rpm. After that, when the engine speed becomes less than the reference speed, the judgment result of step 100 becomes "NO" and the judgment result of step 101 becomes "NO", so the process of step 104 is newly executed and the start flag, that is, the STA flag is It is determined whether or not is "1". At this point
Step 1 since the STA flag is “0”
The determination result in step 04 is "NO", and the process of step 105 is then newly executed to determine whether or not the engine speed is below a minimum reference speed, for example 100 rpm, which is a guideline for engine stall. At this point, since the engine speed has not yet reached 100 rpm, the determination result at step 105 is "NO", and the process at step 103 is then executed. Therefore, until the engine speed decreases below the minimum reference speed, for example, 100 rpm, the series of processes of step 100, step 101, step 104, step 105, and step 103 are performed as follows.
Alternatively, the processes of step 100 and step 103 are executed.

After that, the engine speed is set to the minimum reference speed, e.g.
When the rpm is below 100 rpm, the judgment result in step 105 becomes "YES", step 102 is executed again, and the starting flag, that is, the STA flag, becomes "1".
is set to Therefore, the above-mentioned startup fuel increase process is restarted, the engine speed increases as shown in FIG. 3, and the engine stall does not occur.

FIG. 5 shows a flowchart representing a second embodiment of the invention.

In this second embodiment as well, a predetermined timer interrupt process, for example, a 4 msec timer interrupt process, is performed as in the first embodiment.

This second embodiment is different from the first embodiment as a predetermined reference rotation speed and a minimum reference rotation speed, respectively.
Whereas 500rpm and 100rpm were previously set as fixed, the reference rotational speed and minimum reference rotational speed can be changed in accordance with the cooling water temperature measured by the cooling water temperature sensor 4. For example, as the cooling water temperature rises, Therefore, the reference rotation speed and the minimum reference rotation speed are each made to have a downward tendency. The process of setting these reference rotational speeds is performed in the process of step 200. And other steps 20
Each of the processes from step 1 to step 206 corresponds to step 100 to step 10 of the first embodiment, respectively.
This is the same as each process in 5.

〔Effect of the invention〕

As described in detail above, the fuel increase control method for an electronically controlled internal combustion engine of the present invention includes a rotation speed sensor that detects the rotation speed of the internal combustion engine, a starter switch that detects that the engine is starting, and a starter switch that detects that the engine is starting. It is executed by an electronically controlled internal combustion engine that has an electronic control circuit that receives detection signals from engine sensors including various sensors and controls the opening and closing of the injection valves, and starts when the starter switch detects that the engine is starting. When it is determined that the engine speed has increased to a predetermined reference speed or higher based on the rotational speed signal from the rotational speed sensor, the engine starts the engine. In the fuel increase control method for an electronically controlled internal combustion engine, which stops the fuel increase process for an electronically controlled internal combustion engine, when the starter switch detects that the engine has started, the engine speed is set to a predetermined minimum speed lower than the reference speed. When it is determined that the engine speed has fallen below the reference engine speed, the fuel injection amount is increased by executing the fuel increase process for starting again.

Therefore, according to the present invention, as described above in each of the first and second embodiments, a minimum reference rotation speed that is a guideline for engine stall is set, and after starting,
When the engine speed falls below the minimum reference speed,
By restarting the fuel increase process for starting, engine stall can be sufficiently prevented.

In addition, it is possible to save fuel while starting the engine well.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of an internal combustion engine system to which the present invention is applied, FIG. 2 is an explanatory diagram for explaining a conventional fuel increase control method, and FIG. 3 is a diagram illustrating a conventional fuel increase control method. 4 is a flowchart showing the timer interrupt processing of the first embodiment, FIG. 5 is a flowchart showing the timer interrupt processing of the second embodiment, and FIG. 6 is an illustration of the present invention. It is a basic configuration diagram. 1... Rotation sensor including a rotation speed sensor, 2...
...Starter switch, 4...Cooling water temperature sensor, 6
...Electronic control circuit, 16-1 to 16-n...Injection valve.

Claims (1)

[Claims] 1. A rotation speed sensor that detects the rotation speed of the internal combustion engine, a starter switch that detects that the engine is starting, and an injection valve that receives detection signals from engine sensors including these various sensors. Executed in an electronically controlled internal combustion engine having an electronic control circuit that controls opening and closing, when the starter switch detects that the engine is starting, executes a fuel increase process that increases the amount of fuel injection for starting. At the same time, when it is determined that the engine speed has increased to a predetermined reference speed or higher based on the rotational speed signal from the rotational speed sensor, the fuel for the electronically controlled internal combustion engine stops the fuel increase process for starting. In the increase control method, when the starter switch detects that the engine has been started, if it is determined that the engine speed has fallen below a predetermined minimum reference speed that is lower than the reference speed, the engine starts again. 1. A fuel increase control method for an electronically controlled internal combustion engine, characterized in that the fuel injection amount is increased by executing a fuel increase process for the purpose of the invention.