JPH0326842A - Fuel injector for engine - Google Patents

Abstract

PURPOSE:To secure the superior starting performance by calculating the engine stop period on the basis of a plurality of temperature values having different temperature lowering characteristics which represent the temperature state of the engine and correcting the fuel injection quantity on restart on the basis of the engine stop period. CONSTITUTION:A fuel injection quantity calculating means 2 calculates the fuel injection quantity on the basis of the engine operation state which is detected by a detecting means 1. On the restart of the engine, a plurality of engine temperature detecting means 3 detect the temperature of the respective parts which represent the temperature state of the engine, and the values are compared with a plurality of detection temperature values memorized at the engine stop time point, and a calculating means 4 calculates the engine stop time. The correction quantity for the fuel injection quantity on restart is calculated by a correcting means 5 on the basis of the detected engine stop period, and the fuel injection quantity calculated by the calculating means 2 is corrected. Thus, the large disturbance of the mixing ratio which is actually inhaled into a cylinder on the start or immediately after start is prevented, and the superior starting performance can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to fuel injection amount control during restart in an engine fuel injection device.

(Japanese technology and its am) Automobile engines are equipped with electromagnetic fuel injection valves,
Fuel consumption according to driving conditions through electronic control! N shootings are being carried out.

Generally, in a gasoline engine, the fuel injection valve is installed facing into the intake pipe, so when the engine is started cold, a large amount of fuel adheres to the intake pipe and becomes a wall flow, resulting in the high air-fuel ratio required at startup. There was a tendency that it was not possible to obtain Therefore, the device disclosed in Ir Utility Model Publication No. 57-8326, for example, responds to the input of the main key of the engine by
A predetermined amount of fuel is injected, thereby sufficiently increasing the amount of fuel at startup and supplying a high air-fuel ratio at startup.

However, if the engine is restarted shortly after stopping, fuel adhering to the inner wall of the intake pipe remains when the engine is stopped, and the amount of fuel added at startup becomes excessive, resulting in poor starting performance. Another problem was that the operating stability immediately after startup deteriorated. The present invention has focused on these problems, and aims to provide a device that controls the amount of fuel injection at the time of starting by controlling the flow rate of fuel that has been deposited on the wall before starting.

(Measures Pi for Solving the Problems) In order to achieve the above object, the present invention, as shown in FIG. In the fuel injection device for an engine, the engine fuel injection device includes a means 2 for calculating a fuel injection amount, a means 3 for detecting the temperature of each part representative of the temperature state of the engine, and a plurality of detected temperature values stored in advance at the time the engine is stopped. and,
The engine stop period is calculated based on comparison with the detected temperature value at the next start. and means 5 for correcting the fuel injection amount at the time of restart based on the calculated engine stop period.

(Function) Figure 3 shows the drop characteristics of the cooling water temperature Tw (solid line) and the oil temperature To (dashed line) after the engine is stopped.
As shown by diagonal lines in the figure, changes with a predetermined characteristic depending on the engine stop period.

The present invention calculates the engine stop period based on the difference in the drop characteristics of the cooling water temperature Tw and the oil temperature 'ro, for example, and estimates the fuel wall flow rate before the engine start based on this calculated value, and then calculates the fuel wall flow rate at the time of restart. Correct the injection amount.

This avoids a large disturbance in the mixture ratio that is actually generously drawn in during and immediately after starting, and prevents deterioration in startability such as fogging of the ignition plug. (Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 2 shows a system diagram of an air-fuel ratio control device for an automobile engine. In the same figure, 11 is an air amount sensor;
12 is a crank angle sensor; 13 is a water temperature sensor that detects the cooling water temperature provided on the intake pipe's jacket;
Reference numeral 15 is an oil temperature sensor for detecting lubricating oil temperature, and reference numeral 14 is an 02 sensor for detecting the air-fuel ratio. The control unit 20 receives signals from these sensors and controls the amount of fuel from the fuel injection valve 19 to increase or decrease.

In the control unit 20, a pulse I [ T
i is basically calculated as T i = K X Q/N However, K is a constant, Q is the amount of intake air, N is the engine speed, KT is the increase in amount due to warming and is determined as a function of the water temperature TIl, and KAS is the increase in amount after startup and is determined as a function of the cooling water temperature Tll.
It is determined according to I and the elapsed time after starting, Kt is a correction coefficient that reflects the fuel wall flow rate before starting the present invention, and Ts
is the invalid pulse width based on battery voltage.

Figure 3 shows the drop characteristics of the coolant temperature Tw (solid line) and the oil temperature To (broken #I) when the engine is stopped from a warm-up state where the coolant temperature is 80°C. Based on the differences in specific heat and heat radiation paths, ΔT''To-Tw changes according to predetermined characteristics according to the time elapsed from the time the engine is stopped and the outside air temperature, as shown by diagonal lines in the figure.

Based on the difference in the drop characteristics of the cooling water temperature Tw and the oil temperature To mentioned above, what happens after the engine stops? 4 hours (and the outside temperature Ta, the following recent formula is in place)9 However, T
wb is the cooling water temperature at the point when the engine stops, and Tab is if'A M! at the point when the engine stops. Oil temperature, K. K2 is a constant. t=(Twb-Tw)/K1(Tw-TaL・
l2 )t=(Toh-T(+>/K2(To-TaL
(3) In this embodiment, the elapsed time L and the outside air temperature Ta from the time the engine stopped are calculated based on the above equations (2) and (3), and the fuel wall flow rate before the engine starts is calculated from these calculated values. Estimate and correct fuel injection amount at restart. Note that it is also possible to actually measure the outside air temperature Ta.

For this purpose, the control unit. ,}201. t. Fourth
As shown in the figure, if it is determined in step 21 that the key inch that stops the engine operation is turned OFF, in step 22 the water temperature sensor 13, the oil temperature sensor 15
Based on each detected value, the cooling water temperature Twb and the lubricating oil temperature Tab at the time the engine is stopped are respectively stored in the memory. At the time of restart, fuel injection control is performed according to the routine shown in Figure IIIJ5.

First, in step 23, the cooling water temperature Tw and lubricating oil temperature To at the time of starting are read, and in step 24, each detected value Tw, To. Based on T wb, T ab (
The engine stop period E is calculated using equations (2) and (3).

Next, in step 25, the correction coefficient K is calculated based on this calculated value.
For example, L is subjected to Noreck amplification from a table as shown in FIG. Then, the process proceeds to step 261, where Ti during the fuel injection pulse is calculated using equation (1), and a fuel injection signal reflecting the fuel wall flow rate before startup is output to the fuel injection valve 19.

Figure 7 shows the correction coefficient κ^ after startup used in equation (1.)
In the table example of the initial value of S, it decreases according to the cooling water temperature Tw, and as shown in FIG.
′ decreases according to ′. In this way, by calculating the engine stop period t at the time of starting based on the cooling water temperature T and the lubricating oil temperature TO, and looking up the corrected loss Kt according to this stop period t, the suction pipe is adjusted before starting. It is possible to correct the injection pulse width Ti by reflecting the fuel wall flow rate adhering to the fuel wall. This avoids a large disturbance in the mixture ratio that is actually drawn in at the time of starting and immediately after starting, and prevents deterioration of starting performance such as ignition plug clenching. Also, Figure 9 shows I]3l8! after the start of cooling of Kojijin. This is an experimental result in which the cooling water temperature Tw and the lubricating oil temperature TO were measured to increase during operation. It is also possible to determine how far the situation has progressed and reflect it in the fuel injection amount or ignition timing at the next restart.

(Effects of the Invention) As described above, according to the present invention, in an engine fuel injection device, means for calculating an engine stop period based on a plurality of temperature values representing the temperature state of the engine and having different temperature drop characteristics; Since it is equipped with means for correcting the fuel injection amount at the time of restart based on this calculated value, the fuel injection amount at the time of restart is corrected by estimating the flow rate of the fuel wall adhering to the intake pipe before the engine starts. Therefore, it is possible to avoid a large disturbance in the mixture ratio that is actually easily inhaled at the time of starting and immediately after starting, and to ensure good starting performance.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to claims of the present invention, Fig. 2 is a system diagram of a control system applied to the present invention in an embodiment, Fig. 3 is a drop characteristic diagram of cooling water temperature and lubricating oil temperature, Fig. 4, Q'S5
The figures are seven flowcharts for calculating the fuel injection amount, and FIGS. 6, 7, and 8 are tables and maps of correction coefficients, respectively. FIG. 9 is a diagram showing the rise characteristics of cooling water temperature and lubricating oil temperature. DESCRIPTION OF SYMBOLS 1... Engine operating state detection means, 2... Fuel injection amount detection means, 3... Plural engine temperature detection means, 4
. . . Engine stop period calculation means; 5. Fuel injection amount correction means. Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] Means for detecting the temperature of each part representative of the temperature state of the engine in an engine fuel injection device comprising means for detecting the operating state of the engine and means for calculating the amount of fuel injected into the engine according to the detected value. means for calculating an engine stop period based on a comparison between a plurality of detected temperature values stored in advance at the time of engine stop and a detected temperature value at the next start; and a means for calculating an engine stop period based on the calculated engine stop period. 1. A fuel injection device for an engine, comprising means for correcting a fuel injection amount at the time of starting.