JPH0440539B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides a fuel injection control circuit that determines a basic fuel injection amount based on various operating conditions of an internal combustion engine, and a fuel injection control circuit for detecting the opening degree of a throttle valve. The present invention relates to a method for detecting an abnormality in a throttle sensor in an internal combustion engine having a throttle sensor, and particularly for detecting an abnormality in a throttle sensor in an internal combustion engine that corrects the amount of fuel injection based on the output of the throttle sensor. Regarding the method.

[Prior art] With the electronic control of internal combustion engines in recent years, the amount of fuel injection has come to be calculated by the fuel injection control circuit based on the amount of intake air and the rotational speed of the internal combustion engine. Calculated basic fuel injection amount
Tp has come to be corrected by the output of the throttle sensor.

FIG. 1 shows an example of the flow of signals from the accelerator pedal to the fuel injection valve in such an internal combustion engine. Thick arrows indicate mechanical displacement transfer, thin solid arrows indicate electrical signal transmission, and dashed arrows indicate mechanical displacement detection means. As shown in this figure, when the control of the internal combustion engine becomes highly dependent on electrical signals, the control of the internal combustion engine becomes impaired due to electrical failures such as disconnections, short circuits, etc. Therefore, it has become necessary to establish a method for reliably detecting electrical failures.

Among the electric signals shown in FIG. 1, a method for detecting an abnormality when a failure occurs in the accelerator pedal position detection device is disclosed in Japanese Patent Laid-Open No. 57-26232. According to this document, when the accelerator pedal reaches the fully open or fully closed position, a fully open/closed detection device detects this, and at this time, the output signal of the accelerator pedal position detection device has a value outside a predetermined range. In this case, it is determined that the position detection device is abnormal. If the position detection device fails, the throttle valve will not move as intended by the driver.

However, even if the accelerator pedal position detection device functions normally and the throttle valve is set to the desired opening, if there is an abnormality in the throttle sensor, fuel injection control may be affected. It will be. This is because the fuel injection amount is corrected based on the output signal of the throttle sensor.

[Object of the Invention] An object of the present invention is to provide a method for effectively detecting an abnormality in a throttle sensor without providing a special device to an internal combustion engine.

[Structure of the Invention] In order to achieve the above object, the following abnormality detection method of the present invention is provided.

In an internal combustion engine having a fuel injection control circuit for calculating a basic fuel injection amount based on an intake condition such as an intake air amount of the internal combustion engine and a rotation speed, and a throttle sensor for detecting an opening degree of a throttle valve. , a step of calculating a basic fuel injection amount based on the intake state and rotation speed; a step of reading the output signal of the throttle sensor; and a step of calculating the intake state according to the value of the output signal when the throttle sensor is operating normally. setting a basic injection amount upper limit value that exceeds the maximum value of the basic fuel injection amount that can be calculated based on setting a lower limit value of the basic fuel injection amount that is lower than the minimum value of the basic fuel injection amount that can be calculated based on the basic fuel injection amount and the rotational speed; It is determined that the throttle sensor is abnormal when the injection amount exceeds the basic fuel injection amount upper limit value corresponding to the value of the output signal or falls below the basic fuel injection amount lower limit value. A method for detecting an abnormality in a throttle sensor of an internal combustion engine, including steps.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a configuration diagram of an internal combustion engine for carrying out an embodiment of the throttle sensor abnormality detection method of the present invention. In FIG. 2, reference numeral 1 denotes a known four-stroke spark ignition internal combustion engine mounted on an automobile, in which combustion air is supplied to a combustion chamber through an air cleaner 2, an intake pipe 3, a throttle valve 4, etc. 20 is a fuel injection control circuit for opening the electromagnetic fuel injection valve 5 and supplying fuel to each cylinder. The exhaust gas after combustion is released into the atmosphere through the exhaust manifold 6, exhaust pipe 7, etc.
The intake pipe 3 includes a potentiometer-type intake air amount sensor 8 that detects the air flow rate (hereinafter referred to as intake air amount) taken into the internal combustion engine 1 and generates an analog voltage of a magnitude corresponding to this intake air amount. A thermistor type intake air temperature sensor 9 is provided which detects the intake air temperature and generates an analog voltage having a magnitude corresponding to the intake air temperature. The internal combustion engine 1 also includes a thermistor-type coolant temperature sensor 10 that detects the coolant temperature and generates an analog voltage of a magnitude corresponding to the coolant temperature.
Also provided is a rotational speed sensor 11 that detects the rotational speed of the crankshaft of the internal combustion engine 1 and generates a pulse signal with a frequency corresponding to the rotational speed. As this rotational speed sensor 11, for example, an ignition coil of an ignition device may be used, and an ignition pulse signal from a primary terminal of the ignition coil may be used as a rotational speed signal. Further, the throttle valve 4 is provided with a throttle sensor 12 that detects the opening degree of the throttle valve. The fuel injection control circuit 20 controls the opening time of the electromagnetic fuel injection valve 5 by calculating the fuel injection amount based on the signals from the sensors 8, 9, 10, 11, and 12. , the fuel injection amount is adjusted.

FIG. 3 is a flowchart of an embodiment of the throttle sensor abnormality detection method of the present invention. In FIG. 3, steps 101 and 102 are filled with functions.
Although the settings for F ₁ (V) and F ₂ (V) are listed,
These functions are used to determine whether the throttle sensor is abnormal, and the details will first be explained using FIG. 4.

FIG. 4 shows the output voltage V of the throttle sensor 12.
This is a diagram schematically showing the relationship between the basic fuel injection amount Tp and the basic fuel injection amount Tp calculated by the fuel injection control circuit 20.
The throttle sensor 12 detects the opening degree of the throttle valve 4, and also detects the basic fuel injection amount.
Tp is calculated mainly based on the intake air amount and rotational speed, and these intake air amount and rotational speed change depending on the opening degree of the throttle valve 4, so the throttle sensor 12 is normal. As long as the throttle sensor 12 is functioning properly, a certain correspondence exists between the output voltage V of the throttle sensor 12 and the basic fuel injection amount Tp. Specific output voltage of throttle sensor 12
The value of the basic fuel injection amount Tp varies within a certain range with respect to Va, but it is possible to determine the basic fuel injection amount under all possible operating conditions based on the intake air amount and engine speed. Tp value (maximum value)
It is possible to set an upper limit that exceeds .
Similarly, a lower limit value below the possible value (minimum value) of the basic fuel injection amount Tp can also be set based on the intake air amount and the engine rotational speed. If the above upper and lower limit values are set throughout the output voltages Vs and Vo of the throttle sensor corresponding to the fully closed and fully open states of the throttle valve 4, the function F ₁ ( V) and the function F ₂ that defines the lower limit value
(V) is obtained. Therefore, throttle sensor 1
When the basic fuel injection amount Tp is between the upper limit value F ₁ (Va) and the lower limit value F ₂ (Va) for a specific output voltage Va of 2, the throttle sensor 12 is determined to be normal. , otherwise Tp is F ₁ (Va)
or when Tp is smaller than F ₂ (Va), it can be determined that the throttle sensor 12 is abnormal.

It is assumed that when the throttle sensor 12 is normal, the basic fuel injection amount Tp has become a value corresponding to the position of point A with respect to the output voltage Va of the throttle sensor 12. At this time, for example, if a failure occurs in the throttle sensor 12 and the output voltage of the throttle sensor drops to the voltage Vs corresponding to the fully closed state of the throttle valve, point A in FIG.
It will move to a point. This is because the throttle valve itself actually maintains a predetermined opening degree, so the operating condition of the internal combustion engine hardly changes, and the value of the basic fuel injection amount Tp does not change.
Since point B is in the area where it is determined that the throttle sensor is abnormal, the abnormality of the throttle sensor will be displayed according to the flowchart of FIG.

Next, returning to FIG. 3, to explain the method of the present invention, first, in steps 101 and 102, an upper limit function F ₁ (V) and a lower limit function F ₂ (V) are set.
These functions can be determined once the internal combustion engine is determined, and the functions determined in advance through experiments for the same type of internal combustion engine can be stored in the fuel injection control circuit 20. Next, in step 103, the fuel injection control circuit 2
Calculate the basic fuel injection amount Tp. Step 10
In step 4, the output voltage Va of the throttle sensor 12 is read, and in steps 105 and 106, the basic fuel injection amount upper limit value F ₁ (Va) and the same lower limit value F ₂ for Va are determined.
Calculate (Va). In step 107, Tp is
Determine whether it is between F ₁ (Va) and F ₂ (Va),
If YES, it is determined in step 108 that the throttle sensor is normal; if NO, in step 109, it is determined that the throttle sensor is abnormal. If it is determined that the throttle sensor is abnormal, the abnormality is displayed in step 110.
Step 11 to continue the anomaly detection cycle
Return to step 103 from step 1 and enter the new Tp and Va.
Based on this, the determination of whether the throttle sensor is abnormal will continue.

Steps 101 and 102 are the fuel injection circuit 2.
This corresponds to storing the functions F ₁ (V) and F ₂ (V) in advance in Steps 103 to 109.
Step 110 is to turn on the throttle sensor abnormality indicator lamp based on the signal from fuel injection control circuit 20, and step 111 is to perform calculation processing within the fuel injection control circuit 20. , for example, an abnormality detection activation switch.
It is carried out by ON-OFF. If this abnormality detection activation switch is linked with the key switch of the automobile, abnormality detection of the throttle sensor will be automatically carried out while the internal combustion engine is operating.

FIG. 5 is a flowchart showing another embodiment of the method of the present invention. In this embodiment, the throttle sensor abnormality is detected only when the output voltage V of the throttle sensor 12 reaches the voltage Vo corresponding to the throttle valve fully open state or the voltage Vs corresponding to the throttle valve fully closed state. It is being implemented. Generally, when a throttle sensor malfunctions due to a disconnection or short circuit, its output voltage is Vs
Therefore, it is efficient to detect an abnormality in the throttle sensor only when Vs or Vo is displayed.

In FIG. 5, first steps 201 and 20
2, the basic fuel injection amount upper limit value F ₁ (Vs) in the throttle valve fully closed state and the basic fuel injection amount lower limit value F ₂ (Vo) in the throttle valve fully open state are set. When the throttle valve is fully closed, the basic fuel injection amount Tp does not exceed F ₁ (Vs), and when the throttle valve is fully open, the basic fuel injection amount Tp does not fall below F ₂ (Vo). Next, in step 203, the output voltage V of the throttle sensor is
Determine whether it is equal to Vs. If V is equal to Vs, the process continues to step 205, and if V is not equal to Vs, it is further determined in step 204 whether V is equal to Vo. If V is not equal to either Vs or Vo, it is determined in step 207 that the throttle sensor is normal. On the other hand, when V is equal to Vs, the basic fuel injection amount Tp is determined in step 205.
It is determined whether or not exceeds F ₁ (Vs), and if it does, it is determined in step 208 that the throttle sensor is abnormal. Similarly, when V is equal to Vo,
In step 206, the basic fuel injection amount Tp is set to F ₂ (Vo)
If it is, it is determined in step 208 that the throttle sensor is abnormal. Abnormal display in step 209 and step 21
The continuation of the abnormality detection of 0 is the same as the case shown in FIG.

In the method shown in FIG. 5, compared to the case of FIG. 3, when V is equal to Vs, the determination as to whether Tp is less than F ₂ (Vs) is omitted. The reason is,
The minimum value of the basic fuel injection amount that is possible when the throttle valve is fully closed is the minimum value that can be calculated by the fuel injection control circuit 20, and F ₂ (Vs) is set below this minimum value. Since Tp is F ₂
This is because it will never fall below (Vs). For the same reason, Tp never exceeds F ₁ (Vo) when V is equal to Vo, and the determination of whether Tp exceeds F ₁ (Vo) is also omitted.

[Effects of the Invention] Since the method of the present invention determines whether there is an abnormality in the throttle sensor based on the basic fuel injection amount calculated by the fuel injection control circuit, the method can be used effectively without the need for a special abnormality detection device. Throttle sensor abnormalities can be detected.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the flow of signals from the accelerator pedal to the fuel injection valve of an internal combustion engine to which the method of the present invention can be applied, and FIG. 2 is a diagram showing the flow of signals from an internal combustion engine to which the method of the present invention can be applied. 3 is a flowchart showing an embodiment of the method of the present invention, and FIG. 4 is a combination of the basic fuel injection amount calculated by the fuel injection control circuit and the output voltage of the throttle sensor. FIG. 5, which is a diagram showing the abnormality determination area of the throttle sensor, is a flowchart showing another embodiment of the method of the present invention. 1... Internal combustion engine, 4... Throttle valve, 1
2... Throttle sensor, 20... Fuel injection control circuit, Tp... Basic fuel injection amount, V... Throttle sensor output voltage, F ₁ (V)... Basic fuel injection amount upper limit value function, F ₂ (V)...Basic fuel injection amount lower limit value function.

Claims (1)

[Scope of Claims] 1. A fuel injection control circuit for calculating the basic fuel injection amount based on the intake state such as the intake air amount of the internal combustion engine and the rotation speed, and a throttle sensor for detecting the throttle valve opening degree. an internal combustion engine having the following steps: calculating a basic fuel injection amount based on the intake state and rotational speed; reading the output signal of the throttle sensor; and determining the output signal of the throttle sensor during normal operation. setting a basic fuel injection amount upper limit value that exceeds a maximum value of the basic fuel injection amount that can be calculated based on the intake state and rotational speed in accordance with the intake state and the rotational speed; and when the throttle sensor is in normal operation, the output signal setting a basic fuel injection amount lower limit value below a minimum value of the basic fuel injection amount that can be calculated based on the intake state and rotational speed in accordance with the value of the fuel injection amount while the internal combustion engine is operating; When the basic fuel injection amount calculated by the control circuit exceeds the basic fuel injection amount upper limit value corresponding to the value of the output signal or falls below the basic fuel injection amount lower limit value, the A method for detecting an abnormality in a throttle sensor of an internal combustion engine, including the step of determining that the throttle sensor is abnormal.