JPH01271641A - Device for controlling fuel of engine - Google Patents

Abstract

PURPOSE:To prevent the generation of over-rich at a cold time by providing a fuel feeding quantity restricting means for restricting the maximum value of a fuel feeding quantity which is set by a final fuel feeding quantity setting means to a lower value as an engine temperature is lower, when the engine temperature is lower than a defined value. CONSTITUTION:At a cold time when an engine temperature A is below a set temperature, a cold-time quantity increasing correcting quantity is set B and, thereby a basic fuel feeding quantity F based on an engine operating condition E is corrected and further, other quantity increasing correction such as accelerating correction, etc. is performed. Thus set final fuel feeding quantity C at the cold time is restricted for its maximum value by a fuel feeding quantity restricting means D to prevent overfeeding due to the duplication of various corrections. This maximum value is restricted to the lower value as the temperature is lower, thereby preventing over-rich at the cold time.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an engine fuel control device.

(Prior art) In so-called electronically controlled fuel injection devices, which control the amount of fuel injection by opening and closing an electromagnetic valve type fuel injector installed in the intake passage of the engine using an electronic control circuit, the engine speed and intake The basic fuel injection amount is set based on the air amount, and water temperature correction, feedback correction, etc. are added to this. Further, when the engine is cold, a warm-up amount is increased to ensure combustibility, and when the engine is accelerated, an acceleration amount is increased. Also, increase the amount at startup and increase the amount after starting.

Various corrections are made to the fuel injection amount depending on the operating conditions, such as increasing the output during high load, and further, correction amounts such as battery voltage correction are added to set the final fuel injection amount.

Then, an injection signal having a pulse width corresponding to this final fuel injection amount is output, and the injector is driven by the injection signal.

By the way, in a fuel control system for this type of engine, as described in, for example, Japanese Patent Application Laid-Open No. 106033/1983, when the engine is cold, the warm-up increase is usually increased as the engine temperature is lower. However, when the engine is cold, the post-start amount and acceleration increase are also increased, and in addition to these increase values, output increase correction is also performed at high loads, so when suddenly accelerating immediately after a cold start, etc. These weight increase corrections tend to overlap and result in over-richness, and as a result,
Inconveniences such as engine rev failure are likely to occur.

Conventionally, as described in JP-A-58-28552, for example, the maximum value of the fuel injection amount is set, and when the engine temperature is low, the maximum value is kept constant regardless of the engine speed. It is known that when the engine temperature is high, the engine speed is reduced as the engine speed increases, thereby preventing over-richness at high temperatures and making it possible to perform sufficient fuel increase correction at low temperatures.

However, with this technology, at low temperatures when the fuel injection amount increases, the maximum value of the fuel injection amount is set to a constant value that allows a sufficient increase in fuel as described above, so the maximum value is the limit value of the fuel injection amount. The problem is that it becomes almost ineffective.

(Object of the Invention) The present invention has been made in view of the above-mentioned problems, and aims to increase the amount of fuel during cold conditions in order to obtain combustion stability during cold conditions, while at the same time preventing the overlap with the increase in acceleration, etc. The purpose is to prevent the occurrence of overrichness.

(Structure of the Invention) The present invention relates to the technical idea of preventing over-richness caused by duplication of various fuel increase corrections during cold conditions by limiting the final fuel supply amount.
Its configuration is as shown in FIG. That is, the engine fuel control device according to the present invention includes an operating state detecting means for detecting the operating state of the engine, and a basic fuel supply amount setting means for setting the basic fuel supply amount based on the output of the operating state detecting means. , an engine temperature detection means for detecting the engine temperature, a cold time increase correction amount setting means for setting an increase correction amount for the fuel supply amount when the detected engine temperature is below a set temperature, and various other correction amounts. A final fuel supply amount is set based on the set basic fuel supply amount, cold time increase correction amount, and various other correction amounts, and a final fuel supply amount is set corresponding to the fuel supply amount. a final fuel supply amount setting means for outputting a control signal to a fuel supply device of the engine; and a maximum value of the fuel supply amount set by the final fuel supply amount setting means when the engine temperature is lower than a predetermined value as the engine temperature becomes lower. The present invention is characterized by comprising fuel supply amount limiting means for limiting the amount to a low value.

(Function) When the engine temperature is cold and is below the set temperature, a cold time increase correction amount is set, which corrects the basic fuel supply amount based on the engine operating condition, and also performs other corrections such as acceleration correction. An increase in the amount is corrected. The maximum value of the final fuel supply amount during the cold period set in this way is limited by the fuel supply amount limiting means so that it does not become excessive due to duplication of various corrections. This maximum value is limited to a lower value as the engine temperature decreases, so overriching is prevented when the engine is cold.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is an overall view of one embodiment of the present invention.

In this embodiment, an injector 4 for injecting fuel is arranged in an intake passage 3 communicating with a combustion chamber 2 of an engine 1 in close proximity to the engine body.

Further, a throttle valve 6 is provided upstream of the surge tank portion 5 of the intake passage 3, and an air flow meter 7 is provided upstream of the throttle valve 6 to detect the amount of intake air. An air cleaner 8 is attached to the upstream end of the intake passage 3. An intake air temperature sensor 9 is provided at a position immediately downstream of the air cleaner 8, and a throttle sensor IO is attached to the throttle valve 6. In addition, a crank angle sensor 12 is provided on the camshaft 11 of each engine, and a water temperature sensor that detects the temperature of engine cooling water is provided on the water jacket 14 of the cylinder block 13. 5 is provided.

Output signal of crank angle sensor 12, air flow meter 7
In addition to the intake air amount signal from the intake air temperature sensor 9. Throttle sensor 10. Each output signal of the water temperature sensor 15 is input to a control unit 16. In the control unit 16, first, the engine speed is determined from the output of the crank angle sensor 12, and the basic fuel injection amount (injection pulse width) is set based on this engine speed and intake air amount. The basic fuel injection amount is determined by multiplying the intake air amount divided by the engine rotation by a constant. Then, water temperature correction and the like are added to this basic fuel injection amount, and furthermore, a warm-up increase is performed when the engine is cold. Also, increase the amount at startup and increase the amount after starting.

Increase corrections such as acceleration increase and output increase are performed according to operating conditions, and when the engine is cold, these increases are made larger. In this manner, various corrections are made to calculate the final injection pulse width, but this injection pulse width is guarded when the engine is cold. In other words, the water temperature corresponding to the engine temperature is detected and the water temperature is the set temperature (60°C).
When the fuel injection amount is lower, the upper limit of the fuel injection amount is regulated by a guard value depending on the engine speed. FIG. 3 is a graph showing the guard value (during injection pulse) set according to the engine speed. In the low rotation range, the intake air flow rate is slow, so there is a lot of fuel adhering to the walls, making it difficult to supply fuel to the combustion chamber. Therefore, the guard value is increased on the low rotation side to ensure a sufficient amount of fuel supply.

The control unit 16 also calculates the ignition timing depending on the operating state. Then, an ignition signal is output to the ignition device 17.

FIG. 4 is a flowchart for executing the injection control of this embodiment.

It starts and first reads various signals such as engine speed, intake air amount, and water temperature.

Then, the basic injection pulse width t is calculated from the engine speed and intake air amount, and then various corrections such as warm-up correction and acceleration correction are performed, and the final injection pulse width t1 is calculated by adding battery voltage correction. do.

Next, it is determined whether the engine water temperature is lower than 60°C, and if it is lower than 60°C, the injection pulse width t is maintained as it is.
Perform fuel injection with L.

Further, if the water temperature is lower than 60° C., the guard value j i +ma□ is determined from the engine rotation speed table corresponding to FIG. 3.

Then, it is checked whether t + h' t 1ma□ calculated earlier is larger, and if ti is larger than t t +++ax, injection is performed with the calculated injection pulse width ti.

Further, if t□ is larger than t twaax, injection is performed using the guard value t t+++az at that time as the final injection pulse width.

Note that the present invention is not limited to the fuel injection type engine as in the above embodiment, but can also be applied to engines equipped with various other fuel supply devices such as an electronically controlled carburetor. be.

(Effects of the Invention) Since the present invention is configured as described above, the cold time increase and acceleration can be performed while ensuring the cold time increase for obtaining combustion stability during cold time, especially during cold acceleration. It is possible to reliably prevent over-richness caused by repeated fuel increase corrections such as fuel increase and output increase.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of the present invention, FIG. 2 is an overall diagram of an embodiment of the present invention, FIG. 3 is a control characteristic diagram of the embodiment, and FIG. 4 is a flowchart for executing control of the embodiment. It is. 1: Engine, 4: Injector, 7: Air flow meter, 12: Crank angle sensor, 15: Water temperature sensor, 16
:control unit. Agent Patent Attorney Jun Shinfuji - Figure 1, Figure 2, Figure 3↑, 1! M1 Engine speed Figure 4

Claims (1)

[Claims] (1) Operating state detection means for detecting the operating state of the engine, basic fuel supply amount setting means for setting the basic fuel supply amount based on the output of the operating state detection means, and engine temperature detection means for detecting the temperature of the engine. means, cold time increase correction amount setting means for setting an increase correction amount for the fuel supply amount when the detected engine temperature is below a set temperature, and various correction amount setting means for setting various other correction amounts; The final fuel supply amount is set based on the set basic fuel supply amount, cold time increase correction amount, and other various correction amounts, and a control signal corresponding to the fuel supply amount is output to the engine fuel supply device. and a fuel supply amount limiting means that limits the maximum value of the fuel supply amount set by the final fuel supply amount setting means when the engine temperature is lower than a predetermined value to a lower value as the engine temperature is lower. An engine fuel control device comprising: