JPS6329038A - Electronically controlled fuel injection system for internal combustion engine - Google Patents

Abstract

PURPOSE:To make a good suction air flow rate corresponding to a variation in suction temperature correctable, by having a retrieving suction air flow rate corrected by the suction air flow retrieved according to throttle valve opening and engine speed and the correction factor set by the suction temperature. CONSTITUTION:In this system, there is provided with a retrieving device D which retrieves the suction air flow stored in a suction air flow memory device C on the basis of each output signal out of a throttle valve opening detecting device A and an engine speed detecting device B. And, also there is provided with a setting device F which sets a correction factor of the suction air flow according to the suction air flow retrieved hereat and suction temperature by a suction temperature detecting device E. And, with this correction factor, the suction air flow is corrected by a correcting device G, and on the basis of the suction air flow after being corrected, a fuel injection quantity is set by a fuel injection quantity setting device H. According to this set fuel injection quantity, a fuel injection valve J is constituted so as to be driven and controlled by a drive controlling device I.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and more specifically, a fuel injection amount is set based on detected values of throttle valve opening and engine rotation speed. The present invention relates to an electronically controlled fuel injection device.

<Prior Art> As a conventional device of this type, there is one shown in FIG. 4, for example (see Japanese Patent Application No. 61-008127, etc.).

A throttle valve opening sensor 4 for detecting the opening degree α of a throttle valve 3 interposed in the intake passage 2 of the internal combustion engine 1, and a rotation speed sensor 5 such as a crank angle sensor for detecting the engine rotation speed N are provided. , the detection signals from these sensors 4 and 5 are input to the control unit 6. The ROM of the microcomputer built in the control unit 6 stores the intake air flow rate Q corresponding to each of a plurality of operating regions divided using the throttle valve opening α and the engine speed N as parameters. Data is stored, and based on the detected values of throttle valve opening α and engine rotational speed N, data on the intake air flow rate Q in the corresponding operating region is searched from the data.

Then, the retrieved intake air flow rate Q and rotational speed sensor 5
The basic fuel injection amount 'rp (-KxQ/N; is a constant) is calculated based on the engine rotational speed N detected by Air-fuel ratio feedback correction coefficient β
After calculating the correction numerator s based on the buffer voltage, the final fuel injection amount Tt (=TpxCOEFxβ+Ts
) is calculated.

When the fuel injection amount Ti is set, this fuel injection amount 7'i
An injection pulse signal having a pulse width corresponding to 1 is output to the fuel injection valve 7 to inject and supply a predetermined amount of fuel to the engine.

(Problems to be Solved by the Invention) By the way, when the intake air flow rate Q is searched and determined based on the detected values of the throttle valve opening α and the engine speed N, the intake air temperature Even if the air density changes as a result, if α and N are the same, the intake air flow rate Q used to calculate the basic fuel injection amount Tp will remain the same, so the desired air-fuel ratio will not change due to changes in the intake air temperature. Therefore, in the past, an intake air temperature sensor was provided to detect the intake air temperature, and the intake air flow rate retrieved according to the intake air temperature was corrected.

However, so-called single point injection, in which the fuel injection valve is installed upstream of the throttle valve,
In the system, the fuel vaporizes when the fuel spray passes around the throttle valve, and at this time, the latent heat of vaporization is taken away from the surroundings to change the intake air temperature, so the intake air flow rate is corrected according to the intake air temperature as described above. When attempting to do so, it is necessary to arrange the intake air temperature sensor as close to the throttle valve as possible, which poses a problem in that the layout of parts is restricted.

The present invention has been made in view of the above-mentioned problems, and in a device in which a fuel injection valve is disposed upstream of a throttle valve, the present invention secures flexibility in the location of the intake air temperature sensor, and
An object of the present invention is to provide an electronically controlled fuel injection device that can satisfactorily correct the intake air flow rate based on the intake air temperature.

Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. A controlled fuel injection device,
A throttle valve opening detection means for detecting the opening of the throttle valve, an engine rotation speed detection means for detecting the rotation speed of the engine, and a throttle valve opening detection means for detecting the rotation speed of the engine, corresponding to each operating region in which the throttle valve opening and the engine rotation speed are used as parameters. An intake air flow rate storage means storing the intake air flow rate, and an intake air flow rate storing means for retrieving the intake air flow rate stored in the storage means based on the detected values of the throttle valve opening and the engine rotation speed respectively detected by the detection means. An air flow rate search means, an intake air temperature detection means for detecting the intake air temperature of the engine, and an intake air flow rate detected by the intake air flow rate search means and the intake air temperature detected by the intake air temperature detection means. an intake air flow rate correction coefficient setting means for setting a correction coefficient; an intake air flow rate correction means for correcting the retrieved intake air flow rate with the correction coefficient set by the intake air flow rate correction coefficient setting means; An electronic control system for an internal combustion engine comprising: a fuel injection amount setting means for setting a fuel injection amount based on an intake air flow rate; and a drive control means for driving and controlling the fuel injection valve according to the fuel injection amount set by the fuel injection amount setting means. A controlled fuel injection system was configured.

According to this configuration, the intake air flow rate used for calculating the fuel injection amount is obtained by correcting the searched intake air flow rate using a correction coefficient set based on the searched intake air flow rate and intake air temperature.

The intake air temperature change when fuel spray passes through the throttle valve is approximately determined by the amount of air passing through the throttle valve, so the intake air flow rate is determined based on the detected values of the throttle valve opening and engine rotation speed. A correction coefficient for approximating the actual value to the actual value is determined and stored in advance from the relationship between the search value of the intake air flow rate and the detected intake air temperature through experiments.

Therefore, without providing an intake air temperature detection means near the throttle valve, it is possible to indirectly know the intake air temperature that changes after passing through the throttle valve, and to correct the intake air flow rate in accordance with the intake air temperature.

<Example> An embodiment of the present invention will be described below based on the drawings.

FIG. 2 shows an outline of the system of this embodiment. Note that the same elements as in the conventional example are given the same reference numerals.

A throttle valve opening sensor 4 is attached to the throttle valve 3 installed in the intake passage 2 of the internal combustion engine 1 as a throttle valve opening detection means for detecting its opening α. A rotation speed sensor 5 such as a crank angle sensor is provided as an engine rotation speed detection means for detecting N. Further, an intake air temperature sensor 8 as an intake air temperature detection means for detecting the intake air temperature TA is provided near the upstream side of the nozzle of the fuel injection valve 7 disposed upstream of the throttle valve 3, and these sensors 4, 5 The detection signal from .8 is input to the control unit 6.

The ROM of the microcomputer built in the control unit 6 stores the intake air flow rate Q corresponding to each of a plurality of operating regions divided using the throttle valve opening α and the engine speed N as parameters. In addition, 'rA is stored as an intake air flow rate correction coefficient in accordance with the intake air flow rate Q and the intake air temperature TA.

In the intake air flow rate correction coefficient? A is for approximating the retrieved intake air flow rate Q to the actual value according to changes in the intake air temperature TA, that is, changes in air density, but in this embodiment, it is relatively far from the throttle valve 3. By providing the intake air temperature sensor 8 near the fuel injection valve 7, the above-mentioned search intake air flow rate Q and intake air temperature T can be obtained.
The search is made from a three-dimensional map with A.

That is, when the fuel injected from the fuel injection valve 7 passes through the throttle valve 3, it vaporizes and takes away the latent heat of vaporization, so a change in intake air temperature occurs around the throttle valve 3. If the intake air temperature sensor 8 cannot be installed near the throttle valve 3, and the intake air temperature sensor 8 is installed at a relatively far position upstream from the throttle valve 3 as in this embodiment, the sensor can be placed in the vicinity of the throttle valve 3.
Changes in intake air temperature in the vicinity cannot be detected, and the temperature of intake air actually drawn into the engine 1 cannot be accurately detected.

However, since the intake air temperature change when passing the throttle valve 3 is approximately determined by the intake air flow rate Q passing through the throttle valve 3, the intake air temperature TA on the upstream side of the throttle valve 3 detected by the intake air temperature sensor 8 and the intake air temperature TA detected by the intake air temperature sensor 8 The intake air flow rate correction coefficient KTA is set based on the relationship with the air flow rate Q. Here, the intake air flow rate Q used to search for the intake air flow rate correction coefficient KtA is searched based on the detected values of the throttle valve opening α and the engine rotational speed N, and is determined based on the change in the intake air temperature TA. Although this value does not correspond and is not an actual value, it is used as a guide to know the trend of intake air temperature change, and it is searched based on the relationship between this searched intake air flow rate Q and the detected intake air temperature TA through experiments in advance. A correction coefficient KfA for approximating the intake air flow rate Q to the actual value is determined in advance.

Next, the operation of the electronically controlled fuel injection system having such a configuration will be briefly explained based on the flowchart shown in FIG.

In step 1 (rSJ in the figure, and the same applies hereinafter), the throttle valve opening α1 detected by each sensor 4, 5.8, engine rotational speed N, and intake air temperature TA are input.

In step 2, data on the intake air flow rate Q is retrieved based on the throttle valve opening α and the engine rotational speed N input in step 1.

In step 3, the intake air flow rate correction coefficient KTA set as described above is searched from the intake air flow rate Q obtained as a result of this search and the intake air temperature TA input in step 1.

In step 4, the intake air flow rate Q found in step 2 is
The intake air flow rate correction coefficient 1' (t
By multiplying by t+, the intake air flow rate Q used for setting the basic fuel injection amount 'rp is set (Q-QXKTA). The intake air flow rate Q as a result of this correction is approximated to the actual intake air flow rate Q in response to the change in air density due to the intake air temperature TA, so the basic fuel injection amount can be determined using this intake air flow rate Q. By setting Tp, a desired air-fuel ratio can be obtained.

In step 5, the basic fuel injection amount 'rp is set based on the intake air flow rate Q corrected for the intake air temperature in step 4 (Tp-KXQ/N; K is a constant).In step 6, the engine cooling water temperature, etc. After calculating the various correction coefficients C0EF according to the engine operating state, the air-fuel ratio feedback correction coefficient β, and the correction numerator s based on the buffer battery voltage, the final fuel injection amount Ti (-TpXCOEFXβ+Ts) is calculated.

When the fuel injection 11Ti is set in this way, the control unit 6 outputs an injection pulse signal with a pulse width corresponding to the fuel injection amount Ti to the fuel injection valve 7, thereby injecting and supplying a predetermined amount of fuel to the engine.

As described above, in this embodiment, the control unit 6
are an intake air flow rate storage means, an intake air flow rate retrieval means 2, an intake air flow rate correction means, an intake air flow rate correction coefficient setting means,
This corresponds to fuel injection amount setting means and drive control means.

<Effects of the Invention> As explained above, according to the present invention, a desired air-fuel ratio can be achieved by properly correcting the intake air flow rate in response to changes in the intake air temperature without disposing the intake air temperature detection means near the throttle valve. It has the effect of being able to obtain

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the invention, Fig. 2 is a system diagram showing an embodiment of the invention, Fig. 3 is a flow chart showing fuel injection amount calculation in the above embodiment, and Fig. 4 is a conventional electronically controlled fuel injection system. FIG. 2 is a system diagram showing the device. 1... Engine 2... Intake passage 3... Throttle valve 4... Throttle valve opening sensor 5...
・Rotation speed sensor 6...Control unit 7
... Fuel injection valve 8 ... Intake air temperature sensor Patent applicant Japan Electronics Co., Ltd. Representative Patent attorney Fujio Sasashima Figure 2 Figure 3

Claims (1)

[Claims] An electronically controlled fuel injection device for an internal combustion engine, in which a fuel injection valve is disposed upstream of a throttle valve installed in an intake passage of the engine, and a throttle valve opening detection means for detecting the opening of the throttle valve. , an engine rotation speed detection means for detecting the engine rotation speed, an intake air flow rate storage means for storing an intake air flow rate corresponding to each operating region using the throttle valve opening degree and the engine rotation speed as parameters, and a throttle valve. An intake air flow rate search means for searching the intake air flow rate based on detected values of the opening degree and the engine rotational speed, an intake air temperature detection means for detecting the intake air temperature of the engine, and the searched intake air flow rate and the detected intake air flow rate. an intake air flow rate correction coefficient setting means for setting a correction coefficient for the intake air flow rate according to the temperature; an intake air flow rate correction means for correcting the retrieved intake air flow rate by the correction coefficient; and based on the corrected intake air flow rate. An electronically controlled fuel injection device for an internal combustion engine, comprising: a fuel injection amount setting means for setting a fuel injection amount; and a drive control means for driving and controlling the fuel injection valve according to the set fuel injection amount.