JPH051617A - Intake air amount data input device for electronic control device of internal combustion engine - Google Patents

Abstract

PURPOSE:To input an intake air amount data output from a heat type intake air amount detector for detecting the intake air amount of an internal combustion engine accurately into an electronic control device for controlling the amount of fuel injection, etc., of the engine. CONSTITUTION:When the electronic control device of an internal combustion engine takes in an intake air amount data, an A/D converter 24 makes A/D conversion of a reference voltage taken out by dividing a constant voltage power supply supplied to the level regulating circuit 12 of an intake air amount detector 1, and a correction value calculating means 2 calculates a ratio of a reference voltage set value stored beforehand to a reference value voltage A/D conversion value as a correction value. In addition, the A/D converter 24 makes A/D conversion of the intake air amount detecting signal detected by a detecting circuit 11 and output through a level regulating circuit 12. Then a correction calculation means 3 corrects the intake air amount data A/D- converted by an A/D converter 24 by means of the correction value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air amount data output from a thermal intake air amount detecting device for detecting the intake air amount of an internal combustion engine, and an electronic control device for controlling the fuel injection amount of the engine. The present invention relates to an intake air amount data input device for inputting.

[0002]

2. Description of the Related Art As a device for detecting the amount of intake air in an internal combustion engine, a heat-sensitive resistor (heating resistor) is arranged in the intake passage, and while the resistor is heated, the resistance of the resistor is reduced by the cooling action of the intake air. There is known a thermal type intake air amount detection device that detects a temperature change as a change in the resistance value of the resistor and outputs an electric signal according to the intake air amount.

[0003]

An intake air amount detecting device of this type is connected to an electronic control unit of an internal combustion engine, and its intake amount data is used for fuel injection amount control and ignition timing control performed by the control unit. To be done. The electronic control unit is usually
The intake air amount detection signal from the intake air amount detection device is converted into a digital value through an A / D converter and input to the microcomputer.

However, when the intake air amount detection signal from the intake air amount detection device is converted into a digital value by the A / D converter, the power supply voltage of the intake air amount detection device is supplied from a highly accurate constant voltage circuit. Therefore, the power supply voltage (reference voltage) supplied to the A / D converter of the electronic control unit is easily changed due to temperature changes and the like. Therefore, when the reference voltage of the A / D converter changes, There is a problem that a large error occurs in the intake air amount data that is taken in.

To explain this error in the graph shown in FIG. 6, the curve A in FIG. 6 shows the relationship between the intake air amount and the output voltage Vs of the intake air amount detecting device. Also, the straight line B
Is an accurate power supply voltage Vc that does not fluctuate in the electronic control unit.
The relationship between the output voltage Vs of the intake air amount detection device and the A / D conversion value of the A / D converter when c3 (reference voltage of the A / D converter) is applied, and the straight line C indicates the power supply voltage (A 5 shows the relationship between the output voltage Vs and the A / D conversion value of the A / D converter when the reference voltage of the / D converter fluctuates by 5% and becomes the power supply voltage Vcc2. Further, the curve D shows the relationship between the A / D conversion value of the A / D converter and the intake air amount data after the calculation.

As can be seen from these graphs, A / D
If an accurate reference voltage Vcc3 is applied to the converter,
Accurate intake air amount data DG1 is obtained as shown by the straight line B and the curved line D, but the reference voltage of the A / D converter is the power supply voltage Vc.
When the value fluctuates a lot like c2, the A / D conversion is performed based on this high reference voltage. Therefore, as shown by the straight line C and the curve D, the value HVS2 converted by the A / D converter is HVS2.
Becomes a value smaller than the true value HVS1, and the intake air amount data DG2 calculated from the A / D converted value is calculated smaller than the accurate intake air amount data DG1 and an error occurs.

The present invention has been made to solve the above problems, and can prevent the occurrence of an error in the intake air amount data due to the fluctuation of the power supply voltage of the electronic control unit, that is, the reference voltage of the A / D converter. An object is to provide an intake air amount data input device in an electronic control device for an internal combustion engine.

[0008]

To this end, the intake air amount data input device of the present invention, as shown in the configuration diagram of FIG. 1, has a temperature detecting resistor for detecting temperature and a flow velocity arranged in the intake passage. The detection circuit 11 of the intake air amount detection device 1 is configured by bridge-connecting the flow velocity detection resistor for detection and another resistor, and the intake amount detection signal output from the detection circuit 11 via the level adjustment circuit 12 is transmitted. In an intake air amount data input device for inputting to an electronic control unit of an internal combustion engine, a reference voltage extracted by dividing a constant voltage power source supplied to a level adjusting circuit 12 of an intake air amount detecting device 1 is A / D. The level adjustment circuit 12 is converted and detected by the detection circuit 11.
A for A / D conversion of the intake air amount detection signal output via
/ D converter 24, correction value calculation means 2 for calculating the ratio of the reference voltage set value stored in advance and the reference voltage A / D conversion value as a correction value, and the intake air amount converted by the A / D converter 24 And a correction calculation unit 3 for correcting the A / D conversion value of the signal with the correction value.

[0009]

When the electronic control unit of the internal combustion engine takes in the intake air amount data, the A / D converter 24 first divides the constant voltage power supply supplied to the level adjusting circuit 12 of the intake air amount detecting device 1 and takes out it. The reference voltage is A / D converted, and the correction value calculating means 2 calculates the ratio of the reference voltage setting value and the reference voltage A / D conversion value stored in advance as the correction value. Further, the A / D converter 24 A / D converts the intake air amount detection signal detected by the detection circuit 11 and output via the level adjustment circuit 12. Then, the correction calculation means 3 corrects the A / D conversion value of the intake air amount detection signal converted by the A / D converter 24 with the correction value.

The corrected A / D converted value is calculated from prestored arithmetic expressions or by searching a data map of the converted value and the intake amount to calculate final intake amount data.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a circuit diagram of the thermal type intake air amount detecting device 1 and a block circuit diagram of the intake amount data input device in the electronic control unit of the internal combustion engine.

The intake air amount detecting device 1 comprises a detecting circuit 11, a level adjusting circuit 12, and a reference voltage circuit 16. The detecting circuit 11 includes a flow velocity detecting resistor Rs and a temperature detecting resistor Rt, and a resistor Ra and a resistor Rb. , A bridge circuit in which the resistor Rc is bridge-connected is provided, the middle point of the bridge circuit is connected to the input side of the operational amplifier 13, and the output side of the operational amplifier 13 is connected to the base of the transistor TR that supplies current to the bridge circuit. It

The flow velocity detecting resistor Rs and the temperature detecting resistor Rt of the detecting circuit 11 are fixed as a thin film heating resistor or a heat sensitive resistor on the substrate of the detecting element arranged in the intake cylinder of the internal combustion engine. Therefore, the intake air can be contacted.

The level adjusting circuit 12 has an operational amplifier 15 in which the output side of the detection circuit 11 is connected to the non-inverting input side, and a non-inverting input side in which a constant voltage power supply is connected, and an inverting input of the operational amplifier 15 in which the output side is connected via a resistor. It is configured by the operational amplifier 14 connected to the side, and adjusts the level width of the detection signal of the intake air amount output from the detection circuit 11 to the level width of the signal required by the electronic control unit and outputs it.

Further, the level adjusting circuit 12 is additionally provided with a reference voltage circuit 16 for outputting a stable reference voltage V _R. The reference voltage circuit 16 is configured to divide the power supply voltage Vcc1 of the constant voltage power supply by the resistors R1 and R2 and output a stable reference voltage V _R. The constant voltage circuit is configured with extremely high precision and supplies a stable power supply voltage Vcc1 that hardly changes even when temperature changes or the like.

The electronic control unit 4 includes a CPU 20 and a ROM 2
1. A microcomputer having a RAM 22 as a main part is configured to execute fuel injection amount control and ignition timing control of the internal combustion engine based on program data stored in the ROM 21 in advance. Further, the CPU 20 executes arithmetic processing for calculating intake air amount data as described later.

An A / D converter 24 is connected to the input / output circuit 23 of the microcomputer to input an analog signal such as an intake air amount detection signal. The signal output terminal of the intake air amount detection device 1 is connected to the channel CH1 on the input side of the A / D converter 24 so as to send the intake air amount detection signal Vs.
The output terminal of the reference voltage circuit 16 is connected to H3 so as to send the reference voltage V _R.

In the channel CH2 of the A / D converter 24 of the electronic control unit 4, the above-mentioned reference voltage circuit 1 is provided.
The output voltage of the constant voltage power source different from the constant voltage power source 6 (voltage Vcc1) of 6 is connected by resistors R8 and R9 so as to be input as a reference voltage. This reference voltage is A / D
When the converter 24 inputs another analog signal (for example, a water temperature signal), it is used as a reference signal for comparison.

Next, the processing operation for the electronic control unit 4 to take in the output signal (intake air amount detection signal) Vs of the intake air amount detecting device 1 as intake air amount data will be described with reference to the flowchart of FIG.

When entering this processing, the CPU 20 firstly
In step 100, the reference voltage V _R input from the channel CH3 of the A / D converter 24 is converted into a digital value, and the digital value is converted into the reference voltage A /.
It is stored as the D conversion value HVR.

Next, at step 110, the CPU 20 causes the reference voltage setting value HV previously stored in the memory to be set.
R0 is read, the ratio between the reference voltage setting value HVR0 and the reference voltage A / D conversion value HVR is calculated, and the correction coefficient CC is calculated. This value indicates a deviation (error) of the reference voltage and is used for correcting the A / D conversion value of the output voltage of the intake air amount detection device.

Next, at step 120, the intake air amount detection signal Vs input from the channel CH1 of the A / D converter 24 is converted into a digital value, and the digital value is output from the intake air amount detection value, that is, the intake air amount detecting device. Voltage A / D
It is stored as the converted value HVS.

Next, in step 130, the CPU 20
The corrected A / D converted value HCVS is calculated by multiplying the A / D converted value HVS by the correction coefficient CC.

The CPU 20 then proceeds to step 140.
Then, using this corrected A / D conversion value HCVS,
The final intake air amount data is calculated by searching the data map of the A / D conversion value and the intake air amount from the arithmetic expression stored in advance.

As described above, the intake air amount data of the intake air amount detecting device is converted into A / D by the A / D converter 24 of the electronic control device.
Since it is corrected based on the D-converted reference voltage A / D conversion value HVR on the detection device side, the error at the A / D conversion due to the fluctuation of the constant voltage power supply (voltage Vcc2) of the electronic control device 4 is The reference voltage V _R obtained from the stable constant-voltage power supply on the detector side enables accurate correction.

Further, since the correction coefficient CC is calculated and corrected from the ratio of the A / D converted reference voltage value HVR and the reference voltage setting value HVR0, accurate intake air amount data can be obtained.

FIG. 4 is a graph showing the operation of this embodiment corresponding to FIG. 6 of the prior art. As shown in the graph of FIG. 4, the reference voltage of the A / D converter 24 is an accurate power supply voltage Vcc3. From the power supply voltage Vcc2 to 5% higher, for example, A / D conversion is performed based on this high reference voltage Vcc2, and the slope of the graph changes upward from the straight line B to the straight line C. However, the value HV obtained by A / D converting the output voltage VS of the intake air amount detection device by the A / D converter 24
S is corrected by the correction characteristic straight line E and the true value (HCV
Since S = HVS1), the intake air amount data calculated from the A / D converted value becomes accurate data DG1 with no error.

FIG. 5 shows a circuit diagram of another embodiment. In this embodiment, a circuit for sending the reference voltage V _R to the A / D converter 24 is a circuit for sending an intake air amount detection signal Vs. Have in common. The other circuit configuration is the same as that of the above embodiment.

That is, the operational amplifier 1 of the level adjusting circuit 12
An analog switch 17 is connected to the non-inverting input line 5 of the reference voltage circuit 1 and the output line from the midpoint of the bridge of the detection circuit 11.
The line for extracting the partial pressure of 6 is connected so as to be switched, and the signal line for switching is connected so as to be output from the microcomputer side of the electronic control unit.

When the electronic control unit 4 reads the intake air amount data using this circuit, the following processing is performed instead of step 100 in the above-mentioned flowchart.

That is, first, the analog switch 17 is switched to the reference voltage circuit 16 side, the reference voltage V _R is input to the channel CH1 of the A / D converter 24, and it is A / D converted to the reference voltage A / D. Obtain the converted value HVR. Then, when step 120 is executed, the analog switch 17 is switched to the detection circuit side, and the intake air amount detection signal is input to CH1 of the A / D converter to input A / D.
D conversion is performed to obtain an A / D conversion value HVS. Hereinafter, the intake air amount data is calculated by the same processing as in the above embodiment.

[0033]

As described above, according to the intake air amount data input device in the electronic control device of the present invention, when the electronic control device takes in the intake air amount data, the A / D converter operates as the intake air amount detecting device. The reference voltage extracted by dividing the constant voltage power supply supplied to the level adjustment circuit is
A / D conversion, and A / D conversion of the intake air amount detection signal detected by the detection circuit and output through the level adjustment circuit, and the correction value calculation means stores the reference voltage set value and the reference voltage A / D stored in advance. Since the ratio of the conversion values is calculated as a correction value and the correction calculation means is configured to correct the intake air amount data that has been A / D converted by the correction value, a constant voltage power supply for an electronic control device including an A / D converter. Fluctuates, A / D
When an error occurs during conversion, the intake air amount data is A / D converted according to the reference voltage extracted by dividing the high-precision constant voltage power supply supplied to the level adjustment circuit of the intake air amount detection device. Since the error of is corrected, accurate intake air amount data can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a circuit diagram of an intake air amount detection device and an intake air amount data input device of an electronic control device.

FIG. 3 is a flowchart of an intake air amount calculation process.

FIG. 4 is a graph of the intake air amount and the output voltage of the intake air amount detection signal,
3 is a graph of the A / D converted value and intake air amount data.

FIG. 5 is a circuit diagram of an intake air amount detection device and an intake air amount data input device of an electronic control device according to another embodiment.

FIG. 6 is a graph of a conventional intake air amount and an output voltage of an intake air amount detection signal, and a graph of its A / D conversion value and intake air amount data.

[Explanation of symbols]

 1-intake air amount detection device, 2-correction value calculation means, 3-correction calculation means, 4-electronic control device, 11-detection circuit, 12-level adjustment circuit, 24-A / D converter.

Claims (1)

Claims: 1. An intake air amount detection device in which a temperature detection resistor for temperature detection, a flow velocity detection resistor for flow velocity detection, and another resistor, which are arranged in an intake passage, are bridge-connected. In the intake air amount data input device for inputting the intake air amount detection signal output from the detection circuit via the level adjustment circuit to the electronic control unit of the internal combustion engine, the intake air amount detection device The reference voltage extracted by dividing the constant voltage power supply supplied to the level adjusting circuit is A / D converted, and the intake amount detection signal detected by the detecting circuit and output through the level adjusting circuit is A / D to convert A /
A D converter, a correction value calculating means for calculating a ratio of a reference voltage set value stored in advance and the reference voltage A / D conversion value as a correction value, and A of the intake air amount detection signal converted by the A / D converter. An intake air amount data input device in an electronic control device for an internal combustion engine, comprising: a correction calculation unit that corrects a / D conversion value with the correction value.