JPH0233447A - Engine fuel injection control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to fuel injection control for automobile gasoline engines, and in particular to multi-point fuel injection that detects engine misfire and stops fuel supply to misfiring cylinders. This relates to a control device.

[Conventional technology]

In automobile gasoline engines, various methods have been used to purify exhaust gas. Among these, multi-point fuel injection devices are being widely used as one of the most effective means of fuel systems. This device has better fuel distribution characteristics to each cylinder of a multi-cylinder engine than a carburetor or single point injection, and because there is less fuel adhering to the walls of the intake pipe due to its structure, it provides good exhaust gas performance and responsiveness. It will be done. These satisfactory performances are achieved when the engine's fuel supply system, ignition system, and engine body are all normal, but if one or more cylinders misfires due to some abnormality, so-called raw gas is released and exhaust gas is generated. becomes significantly worse and the catalytic converter overheats. In particular, if only one cylinder misfires, it is difficult for the driver to notice because there is no major problem in driving due to the output obtained from the other normal cylinders. , the catalyst may overheat and be damaged.

In order to solve the above-mentioned problems, a method of detecting a misfire and stopping the fuel supply to the relevant cylinder is proposed, for example, in Japanese Patent Application Laid-Open No.
This is proposed in Japanese Patent No. 23876. Such conventional operation will be explained using the configuration diagram of FIG. 1 and the flowchart of FIG. 2.

Figure 2 shows the configuration of a multi-point fuel injection system, where l is the engine, 2 is the intake pipe, 3 is the throttle valve,
4 is an air flow sensor for detecting the amount of intake air; 5
Numerals a to 5d are fuel injection valves installed in the intake pipes 2a to 2d of each cylinder and driven by electric pulses, 6a to 6d are cylinder pressure sensors that detect the cylinder pressure of the engine 1, and 7 is a crank angle of the engine l. A rotation sensor that generates pulses, 8 an exhaust pipe, 9 a water temperature sensor for detecting cooling water temperature, 1
0 is the air flow sensor 4 and rotation sensor 71. Fuel injection valves 5a to 5a which calculate the required amount of fuel from operating parameters such as the water temperature sensor 9 and are energized in synchronization with engine rotation.
5d and the cylinder pressure sensor 6a.
A control device processes the signal waveforms of 6d to 6d to determine whether there is a misfire in each cylinder, and 11 is a catalyst device that purifies the exhaust gas. Since there is no known example of the operation of the fuel injection control configured as described above, it will be omitted here, and the control device IO is also a micro combinator which is conventionally widely used and consists of a memory, a calculation section, etc. Since it is composed of an input/output circuit, the explanation of its mechanism will be omitted, and the operation procedure will be explained with reference to the flowchart of FIG. 3.

After starting, first, in step 100, the signals of the air flow sensor 4, rotation sensor 7, and water temperature sensor 9 are read, and in step 101, the fuel injection valves 5a to 5 are adjusted based on this information.
5d drive pulse width is calculated. This pulse width is basically approximately proportional to the value obtained by dividing the intake air amount by the engine speed, and the error of the air flow sensor 4 and fuel injection valves 5a to 5d is determined by using the deviation from the median value of the feedback correction amount. The fuel injection valves 5a to 5d that perform the correction inject fuel proportional to the drive pulse width into the intake pipes 2a to 2d of the respective cylinders at every predetermined cycle.
After the air-fuel mixture is combusted in each cylinder, in step 102, the signal waveforms of the cylinder pressure sensors 6a to 6d installed in each cylinder are sequentially read in synchronization with the rotation pulse obtained from the rotation sensor 7.

As shown in Fig. 4, this signal waveform usually has a crank angle of T.
In the vicinity of DC, the pressure increase due to combustion becomes large as shown by the solid line in the figure, but when the relevant cylinder misfires due to some trouble, that is, combustion does not take place, it shows a low value as shown by the broken line. 61-23876)
As shown in , it is possible to detect whether or not each cylinder is misfiring by comparing the in-cylinder pressure at two points before and after TDC, or by comparing the peak value of the in-cylinder pressure. This determination is made in step 103.

Factors that can cause cylinder misfires include malfunctions in ignition system devices (not shown here) such as the ignition coil, igniter, high-voltage cord, and spark plugs, poor contact in the connectors that connect these devices, and dirt on the spark plugs. , failure of the circuit parts 101a to 10]d that drive the fuel injection valves,
There may be combustion failure due to water leaking into the cylinder.

Piezoelectric types and pressure sensors can be used as cylinder pressure sensors, and other methods (vibration,
Misfires can also be detected by using combustion light, etc.).

When a misfire is detected, the drive of the fuel injection valve of the relevant cylinder is stopped in step 104, and discharge of raw gas is prevented.

[Intelligence B that the invention attempts to solve] By the way, factors that cause cylinder misfires include factors that constantly cause misfires such as the failure of the ignition system device mentioned above, as well as factors that cause fuel vaporization to worsen. Under certain operating conditions, misfires may occur temporarily under certain operating conditions, such as misfires that occur due to fuel adhering to the spark plug, or misfires that occur when the fuel becomes hot and bubbles form in the fuel passage, reducing the amount of fuel supplied. There are several factors that can cause misfires. Conventional fuel injection control devices stop the fuel supply even when such a temporary misfire is detected, so there is a problem in that the subsequent driving performance deteriorates significantly.

This invention was made to solve the above-mentioned problems. It detects misfires only when misfires occur constantly, stops the fuel supply to the misfiring cylinders, and prevents the discharge of raw gas and the catalyst. The object of the present invention is to obtain a fuel injection control device that prevents overheating.

[Means to solve the problem]

The engine fuel injection control device according to the present invention includes fuel injection valves in the intake pipes of each cylinder of a multi-cylinder engine, and calculates the required amount of fuel based on operating conditions such as engine load 3 rotation speed and cooling water temperature. In the multi-point fuel injection control device in which each of the fuel injection valves is controlled by an independent drive circuit, there is provided a misfire detection means for detecting the presence or absence of a misfire in each cylinder; is equipped with injection stopping means for stopping the operation of the fuel injector of the cylinder concerned, and operating state detecting means for detecting that the engine is in an operating state in which a misfire may occur even though the engine is normal. When the detection means detects an operating condition in which a misfire may occur, the misfire detection means is prohibited from detecting a misfire.

[For production]

In this invention, when a misfire occurs in a cylinder, the fuel supply to the cylinder is stopped, and the engine is operated in an operating state where a misfire may occur temporarily even though the engine is normal, that is, when the engine is starting or when the engine is starting. Misfire detection can be prohibited within a predetermined period of time, when the coolant temperature is below a predetermined value, or when the coolant temperature is above a predetermined value.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. Here, the difference between the fuel injection control device according to the present invention and conventional devices is that the operating procedure of the microcomputer of the control device 10 has been changed to the flowchart shown in FIG.
The other configurations and operations are the same as those of the conventional example, so their explanation will be omitted.

In the flowchart of FIG. 1, steps 100-
104 is the same as in the conventional example shown in FIG. In step 105, it is determined whether the rotation speed is less than 50° rpm. If the rotation speed is less than 500 rpm, it is determined that the engine is starting, and in step 106, the timer is set to 30.
, and execute steps 102 to 104 (return to step 100. If it is determined in step 105 that the rotation speed is 50 rpm or more, it is determined in step 107 whether or not the timing is every 1 sec. ,1
If the timing is not every sec, the process advances to step 109.

If the timing is every 1 sec, the process advances to step 10B, and if the timer value is not O, the timer value is subtracted by 1, and if the timer value is 0, nothing is done.

As a result, the value of the timer takes a value greater than O for 30 seconds after the rotation speed reaches 5QQrpm, and becomes O thereafter. In step 109, it is determined whether the timer value is 0 or not. If it is not 0, the process returns to step 100 without executing steps 1102 to 104. If the timer value is O, it is determined in steps 110 and 111 whether the cooling water temperature is less than 0°C or greater than 95°C, and if it is less than 0°C or greater than 95°C, step 102 is performed. The process returns to step 100 without executing steps 104 to 104.

In the above embodiment, it is determined that the engine is starting based on the rotation speed being less than 50 Qrpa, but it is determined that the engine is starting based on the fact that the switch of the starting motor (not shown) is turned on. You may.

〔Effect of the invention〕

As explained above, according to the present invention, when the engine is started, where fuel is poorly vaporized and fuel tends to adhere to the spark plug, and within a predetermined time after starting, and when the cooling water temperature is below a predetermined value, the fuel becomes hotter. This detects operating conditions in which misfires are likely to occur even though the engine is normal, such as when the cooling water temperature exceeds a predetermined value due to the generation of bubbles in the fuel passage, reducing the amount of fuel supplied. Since the system does not detect misfires, - Temporary misfires do not stop the fuel supply and deteriorate subsequent driving performance, and they do not occur constantly like ignition system device failures. As for misfires, it is possible to detect them as before, and this allows the fuel to be stopped to prevent raw gas from being discharged and the catalyst from overheating.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing a control procedure in an engine fuel injection control device according to an embodiment of the present invention, FIG. 2 is a configuration diagram of the fuel injection control device, and FIG. 3 is a flowchart of a conventional fuel control procedure. FIG. 4 is a characteristic diagram of the cylinder pressure sensor. 1... Engine, 2... Intake pipe, 5a to 5d...
Fuel injection valve, 6a to 6d...Cylinder pressure sensor, 9...
Water temperature sensor, 10...control device. Agent Masuo Oiwa 3rd (voluntary)

Claims (1)

[Claims] The intake pipe of each cylinder of a multi-cylinder engine is equipped with a fuel injection valve, and the required amount of fuel is calculated based on operating conditions such as engine load, rotation speed, and cooling water temperature, and each fuel injection valve is operated by an independent drive circuit. The multi-point fuel injection control device is configured to include a misfire detection means for detecting the presence or absence of a misfire in each cylinder, and a misfire detection means for stopping the operation of the fuel injection valve of the cylinder after the detection means detects a misfire. The engine includes injection stopping means and an operating state detecting means for detecting that the engine is in an operating state in which a misfire may occur even though the engine is normal, and the operating state detecting means detects an operating state in which a misfire may occur. 1. A fuel injection control device for an engine, characterized in that, when this occurs, misfire detection by the misfire detection means is prohibited.