JPS61201856A - Fuel feed amount control device - Google Patents

Abstract

PURPOSE:To provide a fuel feed amount control device, having high precision at a low cost, by a method wherein signals from a hot wire sensor adapted to detect an intake air flow rate are inputted at intervals of a specified time. CONSTITUTION:In a control circuit 30, signals qa from a hot wire sensor 18 are inputted periodically at intervals of a specified time independently of engine rotation. An integration value, obtained through integration of the aboves throughout a period T of an ignition signal, is divided by the number of times which the signal qa is inputted during the period T to determines a value Qa. The calculated value Qa produces an average means of the output signal qa from the hot wire sensor 18 during the period T serving as an average period to represent a correct intake air amount. This enables an intake air flow rate to be a always measured without using a crank angle sensor independently of the number of revo- lutions of an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to a control device for an internal combustion engine such as an automobile gasoline engine, and particularly relates to a control device for an internal combustion engine such as an automobile gasoline engine. The present invention relates to a fuel supply amount control device for an internal combustion engine that detects air amount and controls fuel injection amount.

[Background of the invention]

As exhaust gas regulations become stricter, electronic fuel control systems, which allow easy air-fuel ratio control, are increasingly being used in automobile gasoline engines.

This system uses an injector (fuel injection valve) and controls the injector using an electrical signal, thereby ensuring that a predetermined amount of fuel is supplied accurately. , Japanese Patent Publication No. 55-1
What is disclosed in Publication No. 34721 will be described below.

In FIG. 2, this figure shows the fuel system of engine 1 in a comprehensive manner, and intake air is supplied to air cleaner 2. Throttle chamber 4. Intake pipe6. and is supplied into the cylinder 8. The gas burned in cylinder 8 is
It passes through the exhaust pipe 0 from the cylinder 8 and is discharged into the atmosphere.

The throttle chamber 4 is provided with an injector 12 for injecting fuel.
The fuel injected from the throttle chamber 4 is atomized in the air passage of the throttle chamber 4 and mixed with intake air to form a mixture, and when the intake valve 14 is opened.

It is supplied to the combustion chamber of cylinder 8.

A throttle valve 16 is provided near the outlet of the injector 12, and this throttle valve 1G is mechanically interlocked with an accelerator pedal and driven by a driver of a car or the like.

Upstream of the throttle valve 16 of the throttle chamber 4, there is an intake air flow rate sensor consisting of an electric heating element (hot wire);
A so-called hot wire sensor 18 is provided, and an electrical signal qa representing the amount of intake air is taken out.

The injector 12 is constantly supplied with fuel pressurized by a fuel pump 22 from a fuel tank 20.
When the control circuit 30 applies the injection signal Ti to the injector 12, fuel is injected from the injector 12 into the intake pipe 6. In addition, the water temperature sensor 24
The 02 sensor 26 functions to detect the cooling water temperature of the engine 1 and generate a temperature signal TV, and the 02 sensor 26 functions to measure the 02 concentration in exhaust gas and generates an electric signal λ.

Incidentally, in such a control device, the above-mentioned injection signal T i is usually calculated as follows.

T i = T p - k z + 'r.

Here, 'l'P: Engine load = k l ・Q a
-Tkl: Constant TO: Compensation determined by the injector Qa: Intake air flow rate T=1/N N: Engine speed Therefore, in such an electronic fuel control method.

It is necessary to constantly and continuously measure the intake air flow rate Qa of the engine, and for this reason, a hot wire sensor 18 for measuring the intake air flow rate is provided as in the control device shown in FIG.

However, while such hot wire sensors generally have fairly good responsiveness, the engine intake air flow rate is typically accompanied by significant pulsations.

As a result, as mentioned above, when trying to measure the intake air flow rate of an engine using a hot wire sensor, the electrical signal qa from this sensor is accompanied by quite large pulsations, as shown in Figure 3. Therefore, it is necessary to average this signal q& to obtain the intake air amount Qa.

Therefore, in the past, a so-called crank angle sensor was installed on the engine crankshaft, and a signal qa from the sensor was acquired at each predetermined rotation angle during one rotation of the engine, and the signal qa was averaged over a plurality of predetermined rotation angles to calculate the intake air. Flow rate Q
A method was used to obtain a. Regarding the signal processing of such a hot wire sensor, see 1, for example, Japanese Unexamined Patent Publication No. 5
This is disclosed in Japanese Patent No. 6-92330 and the like.

However, this conventional method requires a crank angle sensor, which increases costs, and when the engine speed increases, the signal acquisition interval from the hot wire sensor becomes too short, making it difficult for signal processing to keep up with the process. On the other hand, in a region where the engine speed is low, the signal acquisition interval becomes too long, and pulsation is likely to be picked up, resulting in a decrease in accuracy.

[Purpose of the invention]

It is an object of the present invention to eliminate the drawbacks of the prior art described above, to measure the intake air flow rate with a hot wire sensor without using a crank angle sensor, and with high precision regardless of the engine speed, and to achieve low cost and high precision measurement. An object of the present invention is to provide a control device that enables fuel supply amount control.

[Summary of the invention]

In order to achieve this object, one aspect of the present invention is that a signal from a hot wire sensor for detecting the intake air flow rate is taken in at regular time intervals.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fuel supply amount control device according to the present invention will be described in detail below with reference to illustrated embodiments.

Note that one embodiment of the present invention has a second hardware configuration.
It is the same as the conventional example explained in the figure, but the microcontroller (
The only difference is the signal processing for determining the intake air flow rate QQ based on the signal qa of the hot wire sensor 18 by the control circuit 30 including a microcomputer.
This point will be emphasized in the explanation.

FIG. 1 is a time chart showing the operation of one embodiment of the present invention, in which the ignition signal shown in FIG. 1(a) is cursed in synchronization with the rotation of the engine, while the The signal qa from the hot wire sensor 18 representing the quantity is taken periodically every predetermined period of time 5, for example, 2.5 msec, regardless of one revolution of the engine. Find the integrated value Σq integrated over T,
This integrated value Σqte is divided by the number n of times the signal qa is taken in during the period T to obtain the intake air flow rate Qa.

4 and 5 are flowcharts explaining the operation in one embodiment of the present invention. The process in FIG. 4 is periodically executed every 2.5 msec by a timer interrupt, and the process in FIG. It is to be executed in synchronization with the rotation of the engine by the ignition signal. First, when the process shown in FIG.
Step 1111m) is hot wire sensor 18
Capture the electrical signal qa which is the output of
In step 2, it is successively integrated into the previous integrated value Σ9 to obtain a new integrated value Σq, and in the final step 83, 1 is added to the count number n.

On the other hand, in the process shown in FIG. 5, the SIO first divides the integrated value Σq by the count number n to calculate the intake air flow rate Qa, and the primary Sll clears the integrated value Σq and the counted value n. Next, in S12, the period of the ignition signal] is measured, and based on the period 'r obtained from this and the intake air flow rate Qa obtained in step 310, the next processing in S13 and 314 is performed to calculate the period that should be given to the injector 12. The injection time T1 is calculated, thereby creating the fuel injection pulse shown in FIG. 1(c).

Here, looking at the integrated value Σq, it is cleared in Sll every time an ignition signal appears in the process shown in Figure 5, but at the same time, the signal 9a is integrated by 81.52 every 2.5 m1/J) in the process shown in Figure 4. Therefore, the integrated value Σq, which becomes the dividend in the SIO process of FIG. 5, is the 11th! l
As shown in (a>, (b'')).

Hot wire sensor 1 for every /1lXlfT of ignition signal
This is the value obtained by integrating the output signals qa of 8.

Also, regarding the count number n, it should be cleared in Sll every time the process shown in FIG. 5 is started.

It is incremented in S3 every time the process shown in FIG. In the process of FIG. 5, the divisor n is 310.

Therefore, the value Qa calculated at 810 in the process of FIG.
is the average value of the output signal ITa of the hot wire sensor 18 with the period wJT shown in FIG. 3 as the averaging period, and represents the correct intake air flow rate. Incidentally, the circle marked on the curve representing the signal qa in FIG. 3 represents the point at which this signal qn is taken in.

According to this embodiment, IL does not use the information representing the engine rotation angle to take in the No. 1 signal from the hot wire sensor, so there is no need for a crank angle sensor, and this signal is always taken in. Since this is done at fixed time intervals, there is no risk that the processing will not be able to keep up even if the engine speed becomes high.On the other hand, even when the engine speed is low, the measured intake air amount The injection time Ti can always be calculated accurately without the risk of pulsation occurring in Q(l).

Note that the above explanation deals with the case where a thermal linear intake air flow sensor is used as an intake air flow sensor (also referred to as an air flow meter), which may cause pulsation in the detection signal in response to engine intake pulsation. Although described above, the present invention is not limited to this.

It goes without saying that the same effect can be expected by applying any type of intake air flow rate sensor that generally has good response characteristics.

〔Effect of the invention〕

As explained above, according to the present invention, signal processing is performed at predetermined regular intervals when it is necessary to obtain the intake air method by averaging the detection signals, thereby eliminating the drawbacks of the prior art. , provides a low-cost fuel supply amount control device that does not require a crank angle sensor, can always accurately measure the intake air flow rate regardless of the engine speed, and can control the fuel supply amount with high precision. can do.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the operation of an embodiment of the fuel supply amount control device according to the present invention, and FIG. 2 is an illustration of the electronic fuel supply side #
A block diagram showing an example of the II device, and FIGS. 3 and 4 are flowcharts showing the operation of an embodiment of the present invention, respectively. 1... Engine, 12... Injector (fuel injection valve), 18... Hot wire sensor. Figure 1 T → (0) Taku, Noko No. 115 Figure 2 n

Claims (1)

[Claims] 1. In a fuel supply amount control device for a fuel injection type internal combustion engine that is equipped with a thermal linear intake air amount sensor and controls the fuel supply amount according to the amount of intake air, the output signal of the thermal linear intake air amount sensor is controlled at a predetermined constant level. A means for acquiring and integrating the values at time intervals and a means for averaging the accumulated values by the number of times of acquisition are provided, and the averaged value is configured to obtain a signal representing the intake air amount. A fuel supply amount control device characterized by: