JPH06167239A - Method and apparatus for obtaining quantity of fuel supplied to internal combustion engine - Google Patents

Abstract

PURPOSE: To compensate for manufacturing variations, changes or drifts due to operation time so as to determine the correct fuel quantity by detecting at least another signal indicating fuel quantity when one signal indicating fuel quantity is determined on the basis of the signals relative to injection period, and producing an average value of these signals. CONSTITUTION: Fuel is supplied from a fuel pump 110 to an internal combustion engine 100. The fuel quantity is determined on the basis of a drive signal of an actuator 120, produced by a control device 130. The control device 130 inputs at least the respective detected signals from a sensor 150, including the engine speed and fuel temperature, and the detected signals from sensors 160, 164, 168 with respect to the fuel pump 110 and the internal combustion engine 100. An average value thereof is produced in a circuit 134 on the basis of the detected signals. The fuel quantity is calculated in a circuit 136 and the drive signal of the actuator 120 is calculated in a circuit 132. The fuel quantity signal calculated in the circuit 136 is also inputted to another control device 140.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for determining the fuel quantity supplied to an internal combustion engine, and more particularly to an internal combustion engine in which a first signal indicative of the fuel quantity is determined on the basis of a signal relating to an injection period. The invention relates to a method and a device for determining the amount of fuel supplied to an engine, in particular a self-ignition internal combustion engine.

[0002]

2. Description of the Related Art Such a method and apparatus is a DE-OS
It is known from 3032381 (US-A 4762107). The publication describes a control device for a self-ignition type internal combustion engine that includes an injection nozzle and a needle valve that moves inside the injection nozzle. A sensor detects the position or movement amount of this needle valve and generates a corresponding detection signal. The processing circuit obtains the injection period signal indicating the fuel injection period to the internal combustion engine based on the detection signal, and the fuel amount can be obtained from the injection period signal. This fuel quantity is used as a load signal when setting the injection start and / or the exhaust gas recirculation rate in relation to the operating parameters.

[0003]

Due to fluctuations or variations, this signal will no longer accurately reflect the amount of fuel actually injected. Such an inaccurate fuel quantity results in an inaccurate control of the exhaust gas recirculation rate or the injection start, resulting in an increase in exhaust gas emission.

DE-OS 3118425 (US-A44
A device for detecting the amount of fuel supplied from 26981) to the combustion chamber of a diesel engine is known. This device has a pressure sensor for detecting the pressure in the pump unit and a circuit device for determining the fuel amount based on the signal of the pressure sensor.

Due to fluctuations or variations in the nozzle opening pressure or closing pressure of the injection valve, the accuracy of the fuel amount becomes inaccurate in this device as well. In particular, a drift phenomenon appears in the fuel metering device, and the relationship between the detected signal and the actually injected fuel amount changes as the internal combustion engine runs.

DE-OS 3011595 (US-A44
26980), a device for compensating for such a drift phenomenon is known. This device compensates for the relationship between the signal concerning the position of the control rod and the fuel quantity. However, this device cannot compensate for variations between individual pump manufactures. This device is also unsuitable for a solenoid valve-controlled fuel metering device. Because there is no control rod.

In the solenoid valve control device, the solenoid valve closing period is used as the fuel amount.

The object of the present invention is to provide a method and a device for determining the quantity of fuel supplied to an internal combustion engine, which makes it possible to determine the quantity of fuel very accurately without drifting.

[0009]

According to the invention, the object is to determine a first signal indicative of the fuel quantity on the basis of a signal relating to the injection period and to detect at least one other signal indicative of the fuel quantity. The first to determine a fuel quantity signal
Is solved by the configuration in which the average value of the signal of and the other signal is formed.

[0010]

With this structure, it is possible to form a fuel amount without drift.

Preferred embodiments and variants of the invention are described in the dependent claims.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings.

Fuel is supplied to the internal combustion engine 100 from a fuel pump 110 through a fuel pipe. The amount of fuel supplied to the internal combustion engine 100 is determined by the actuator 120 based on the drive signal Ti. The drive signal Ti is generated by the controller 130. Controller 130 processes the signals of various sensors 150. These sensors 150
Supplies at least the speed signal as well as the fuel temperature signal. Further, the control device 130 includes sensors 160, 164, 1
The output signal from 68 is provided.

The output signals of these sensors are input to the average value forming circuit 134, and then input to the fuel amount calculation circuit 136. This fuel quantity calculation circuit further processes the output signal from the sensor 150. The drive signal Ti is calculated by the drive circuit 132 based on the sensor signal. The output signal of the fuel amount calculation circuit 136 is input to another control device 140.

The other control device 140 adjusts, for example, the exhaust gas recirculation rate, the injection start or the maximum allowable injection fuel amount, and the like.

The sensors 160, 164, 168 generate a signal from which the fuel quantity injected is calculated. For distributed and in-line pumps, the sensor 160 is a sensor that produces a signal RW relating to the position of the control slider (rack) or control rod. This signal is usually called the control slider movement amount or the control rod movement amount. This signal is used by a positioning controller (actuator) to adjust the control rod or control slider to a set position. A first signal QRW representing the fuel quantity is obtained on the basis of this signal corresponding to the position of the control rod or control slider.

Further, a sensor 164 for detecting the pressure in the pump unit space is provided. The period during which the pressure in the unit space becomes equal to or higher than the threshold value is usually called the pressure duration ED of the unit space. This pressure continuation period ED also becomes a value representing the amount of fuel actually injected. This pressure duration E
A second signal QED indicating the fuel quantity is obtained on the basis of D and possibly other operating parameters and constants. Pressure duration ED of sensor and unit space and second signal QED
Corresponding signal processing for obtaining
3118425 (US-A 4426981).

The sensor 168 is a sensor for detecting the actual start of injection and the actual end of injection. This sensor detects the opening period of the injection valve. The opening period is also called a normal injection period SD. A third amount of fuel that is represented by this injection period SD and other operating parameters and constants
Signal QSD is obtained. The corresponding signal processing for determining the sensor and the injection period SD and the third signal QSD is:
For example, DE-OS3032381 (US-A47621)
07).

The sensors described above are usually provided in row and distributed injection pumps. In the case of a solenoid valve controlled pump, there is no control rod or control slider, and instead a solenoid valve is provided. The start and end of injection are controlled by this solenoid valve. Normally, this solenoid valve is driven so that the injection start is fixed when the solenoid valve is closed and the injection end is fixed when the solenoid valve is opened. Solenoid valve closing period MD based on the exact moment when the solenoid valve opens and closes
Is obtained. This signal for the solenoid valve closing period MD is replaced by the signal RW. A fourth signal QMD indicating the fuel amount is obtained based on the electromagnetic valve closing period MD.

Methods and devices are known for determining the fuel quantity based on the opening and closing times of the solenoid valve. In one method, a sensor is provided to detect movement of the solenoid valve needle. Furthermore, there is a method of detecting the exact opening and closing times of the solenoid valve based on the current flowing through the solenoid valve or the voltage applied to the solenoid valve.

The signals produced by these sensors, which represent the fuel quantity, are of limited accuracy. If the fuel amount thus obtained is used to control another amount, the error during control becomes noticeable.

The exhaust gas recirculation rate is usually adjusted according to the amount of fuel injected. Inaccurate fuel quantities likewise result in inaccurate exhaust gas recirculation and increased exhaust gas emissions. In addition, the fuel quantity is needed to set the start of injection as well as to determine the maximum allowable fuel quantity. Therefore, it is necessary to obtain this signal with the highest possible accuracy.

The relationship between the output signals of various sensors and the amount of fuel actually injected changes as the operating time of the fuel metering device elapses. This phenomenon is usually called drift. This inaccuracy or drift is due to the variation or variability of the position of the delivery plunger relative to the control slider or control rod. Further, the nozzle opening pressure or closing pressure of the injection valve changes.

According to the present invention, it has been revealed that various drift characteristics appear in various signals indicating the fuel amount. Various fuel amounts from each sensor are affected differently by changes in the nozzle opening pressure. When the control slider movement amount RW, the control rod movement amount RW, the unit space pressure ED or the electromagnetic valve drive time MD is constant, the fuel amount QK increases when the nozzle opening (closing) pressure decreases. When the injection period SD is constant, the fuel amount QK decreases when the nozzle opening (closing) pressure decreases.

Therefore, in the present invention, the average value of at least two signals is processed instead of one signal. An average value forming circuit forms an average value from at least two signals obtained from the sensors 160, 164, 168. Preferably, the average value is formed from the third signal QSD obtained from the injection period SD as well as the other signals. In a simple embodiment, the arithmetic mean is formed according to the following equation: QK = (QSD + QMD) / 2 QK = (QSD + QRW) / 2 QK = (QSD + QED) / 2.

In a particularly preferred embodiment, a weighted average value is formed. In this case, the fuel amount QK is obtained, for example, according to the formula QK = (A * QSD + B * QMD) / 2. A and B are constants chosen such that A + B = 2. In another embodiment of the invention, 3
Computing the average value from one or more signals is performed.

With the signal indicative of the fuel quantity, the error of the individual signals can be compensated by forming an average value from at least two signals having different drift characteristics. The averaged signal is more accurate than the individual signals, in which case the accuracy gain is usually greater than that obtained for averaging.

[0028]

As described above, according to the present invention, it is possible to obtain an accurate fuel amount signal that compensates for variations in manufacturing or fluctuations or drifts due to the passage of operating time.

[Brief description of drawings]

FIG. 1 is a block diagram schematically showing a configuration of the present invention.

[Explanation of symbols]

 100 Internal Combustion Engine 110 Fuel Pump 120 Actuator 130, 140 Control Circuit 150, 160, 164, 168 Sensor

Claims (8)

[Claims] 1. A method for determining a fuel amount (QK) supplied to an internal combustion engine, in particular a self-ignition type internal combustion engine, wherein a first signal (QSD) indicating the fuel amount is a signal relating to an injection period (SD). At least one other signal indicative of the fuel quantity is detected, and the first signal (QSD) and the other signals (QRW, QED, QMD) to determine the fuel quantity signal (QK). A method for determining the amount of fuel supplied to an internal combustion engine, characterized in that an average value of 2. Method according to claim 1, characterized in that the average value is formed from the average value of two signals representative of the fuel quantity. 3. The method of claim 1, wherein the average value is formed from the average value of three signals indicative of fuel quantity. 4. The other signal (QRW) is a control slider movement amount or a control rod movement amount (R).
Method according to any one of claims 1 to 3, characterized in that it is set according to W). 5. The method according to claim 1, wherein the further signal (QED) is set on the basis of the pressure duration (ED) of the pump unit space. 6. The method according to claim 1, wherein the further signal (QMD) is set on the basis of a solenoid valve closing period (MD). 7. The method according to claim 1, wherein a weighted average value is formed. 8. A fuel quantity (QK) supplied to an internal combustion engine, in particular a self-ignition type internal combustion engine, comprising means for determining a first signal (QSD) indicative of the fuel quantity based on a signal relating to the injection period (SD). Means for detecting at least one other signal indicative of fuel quantity, said first signal (QSD) and other signals (QRW, QED, QMD) for determining a fuel quantity signal (QK) A device for determining the amount of fuel supplied to the internal combustion engine, comprising: