JPH01310166A - Classifying and assembling method for fuel injection valve of multicylinder internal combustion engine - Google Patents

Abstract

PURPOSE:To aim at improving the accuracy of air-fuel ratio control by measuring the fuel flow values of plural fuel injection valves so as to classify them into groups and assembling the fuel injection valves of the same group to a cylinder corresponding to one exhaust density detector. CONSTITUTION:In the fuel injection valve 6 judged as being within the fixed standard in the manufacturing process, the flow characteristics are measured at least in two points, that is, in small flow and large flow, classified into the groups of similar flow characteristics, and the fuel injection valves of the same group are provided with the same identification code. For example, in a six-cylinder engine 1, in case of detecting the density of the exhaust gas out of cylinders 21-23 by means of an O2 sensor 12a and the density of the exhaust gas out of cylinders 24-26 by means of an O sensor 12b, and providing them with air fuel ratio control by means of an ECU 7, the fuel injection valves 61-63 and 64-66 of the cylinders corresponding to the O sensor 12a, 12b respectively are provided with the same identification codes. The accuracy of air-fuel ratio control is thus improved.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a selection set (=
In particular, the present invention relates to a method for selecting and assembling fuel injection valves for an internal combustion engine including a fuel injection control device that controls the air-fuel ratio of the air-fuel mixture supplied to each cylinder in accordance with the oxygen concentration in exhaust gas.

(Prior art) Conventionally, the valve opening time of a fuel injection valve arranged corresponding to each cylinder of a multi-cylinder internal combustion engine is set to a reference valve opening time depending on the engine speed and the absolute pressure in the intake pipe, for example, and the engine exhaust Set by correcting with a correction value according to parameters including the oxygen concentration in the exhaust gas detected by the exhaust gas concentration detector (hereinafter referred to as "02 sensor") installed in the system,
Fuel injection control for a multi-cylinder internal combustion engine that performs feedback control to control the air-fuel ratio of the air-fuel mixture supplied to the engine to the stoichiometric mixture ratio of 14.7, which provides the maximum conversion efficiency of the three-way catalyst disposed in the engine's exhaust system. A device is commonly used (Japanese Patent Application Laid-open No. 116044/1983).

In such a multi-cylinder internal combustion engine, in order to reduce the cost and simplify the control device, one or two 02 sensors are usually installed in the exhaust system, so one 02 sensor is The oxygen concentration in the exhaust gas from two or more cylinders will be detected. By the way, the air-fuel ratio feedback control described in n;
When performing this on a 6-cylinder internal combustion engine equipped with 2 sensors, the output signals from each 02 sensor are processed separately to obtain their respective correction values, and the fuel output to the corresponding 3 cylinders detected by each 02 sensor is calculated. By correcting the injection amount (valve opening time) using each of the above correction values, the air-fuel ratio of the air-fuel mixture is controlled to the stoichiometric mixture ratio with a certain degree of accuracy.

By the way, only fuel injection valves whose flow characteristics are determined to be within a certain standard are used in the fuel injection control device. More specifically, the flow rate characteristics of the injection valve are the actual fuel flow J'kQl (mm'') at a small fuel flow rate (for example, the valve opening time is 2 m5ec) and the actual fuel flow J'kQl (mm'') at the time of a large fuel flow rate (for example, the valve opening time is 24 m5ec) and the fuel flow ff1Q2 (+nm
”), and whether or not the injector is within the above-mentioned constant regulation path is determined by the respective fuel flow ffi Q l.

It is judged based on whether Q2 is within a predetermined tolerance range (±3% at small flow rate, ±2% at high flow rate) suitable for fuel injection control centered on the design target value (median value). (4th
figure).

(Problem to be Solved by the Invention) However, the predetermined tolerance range representing the above-mentioned fixed path is
Since this is a criterion for determining pass/fail in the manufacturing process of fuel injection valves, there are still individual differences between fuel injection valves, even if they are good quality fuel injection valves that meet certain standards. may affect the actual air-fuel ratio control.

That is, when a plurality of fuel injection valves are opened for the same reference valve opening time described above, the amount of fuel injected and supplied to the corresponding cylinder varies depending on the individual differences. Such a difference in fuel amount is originally to the extent that it can be compensated for by correcting the fuel amount using air-fuel ratio feedback control. However, in the fuel injection control device for a multi-cylinder internal combustion engine that detects the oxygen concentration in the exhaust gas from multiple cylinders using one 02 sensor as described above, there is a difference in the amount of fuel in each cylinder,
In other words, it is not possible to individually detect the air-fuel ratio bias for each cylinder, and even if the apparent air-fuel ratio of the mixture determined by the 02 sensor matches the theoretical mixture ratio, the air-fuel ratio is actually There are cases where some cylinders are on the rich side and some cylinders are on the lean side, and in this case, the three-way catalyst cannot sufficiently purify the LrC1Go and NOx components in the exhaust gas across all cylinders. A problem occurs.

(Object of the invention) The present invention has been made in view of the above circumstances, and
In a fuel injection device for a multi-cylinder internal combustion engine in which a sensor detects oxygen concentration in exhaust gas from multiple cylinders, the accuracy of air-fuel ratio control according to the output signal from the 02 sensor is further improved. The purpose of this invention is to provide a method for sorting and assembling fuel injection valves corresponding to common 02 sensors.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a plurality of fuel injection valves that intermittently inject and supply fuel to corresponding cylinders of a multi-cylinder internal combustion engine, and at least two or more fuel injection valves. - an exhaust concentration detector that detects the oxygen concentration in the exhaust gas discharged from the L cylinder; and an exhaust concentration detector that detects the amount of fuel supplied by the fuel injection valve corresponding to the cylinder based on the output signal from the exhaust concentration detector. and a fuel injection control device for controlling an air-fuel ratio of an air-fuel mixture supplied to the cylinders to a target air-fuel ratio. Fuel flow values of a plurality of fuel injection valves within a tolerance range are measured at at least two points, one at a small flow rate and one at a large flow rate, and the fuel injectors are classified into a plurality of groups based on the measured fuel flow values. At the same time, the same identification symbol shall be attached to the fuel injection valves belonging to the same classified group.
A method for selectively assembling fuel injectors for a multi-cylinder internal combustion engine, characterized in that only fuel injectors given the same identification symbol (=1) are assembled into a cylinder corresponding to one exhaust gas concentration detector. is provided.

(Function) A fuel injection valve that was determined to be within a certain standard at the time of manufacture,
Furthermore, since fuel injection valves in the same group are classified into groups with similar flow characteristics and the same identification symbol is given to the fuel injection valves in the same group, it is possible to determine whether the injector is good or not and determine which injector is usable. In addition to securing the number as usual, one 0
Since the cylinders sensed by the two sensors are only equipped with the same identification symbol, the accuracy of air-fuel ratio control is further improved.

Furthermore, when replacing a malfunctioning fuel injector during maintenance or the like, the injector can be easily replaced with an injector that has the same identification symbol, so that highly accurate air-fuel ratio control can continue to be performed.

(Embodiment of the Invention) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing the overall configuration of a fuel injection control device for an internal combustion engine to which the method of selecting and assembling fuel injection valves of the present invention is applied, and 1 in the figure indicates a V-type 6-cylinder internal combustion engine.

0 (I) The first, second and third cylinders 21, 22 and 23 (first cylinder group) are in one bank l^ of the engine l, and the fourth cylinder 115 and the sixth cylinder are in the other bank 18. 2
L 25 and 26 (second cylinder group) are arranged and 0;
The exhaust passage 3^ of the first cylinder group and the exhaust passage 3B of the second cylinder group are formed separately from each other. On the other hand, the intake passage 4 is common to both cylinder groups, and a throttle valve 5 is interposed in the middle of the intake passage 4.

Each intake boat of the first to sixth cylinders 21 to 26 is provided with fuel injection valves 61 to 66, respectively, and the control system for these fuel injection valves 61 to 66 is controlled by the first cylinder group (first to sixth cylinders).
3rd cylinder group 21-23) and 2nd cylinder group (4th-6th cylinder group)
The cylinders 24 to 26) are independently separated. Each of the fuel injection valves 61 to 66 is connected to a fuel injection pump (not shown) and electrically connected to an electronic control unit (hereinafter referred to as ECU) 7 that executes arithmetic processing of data necessary for air-fuel ratio control. The opening/closing operation is performed by a drive signal supplied from the ECU 7.

An absolute pressure sensor (hereinafter referred to as PB sensor) 9 is connected to the intake passage 4 on the downstream side of the throttle valve 5 via a connecting pipe 8, and detects the absolute pressure Pa^ in the intake passage 4. The electrical detection signal output from the PB^ sensor is input to the ECU 7.

An engine rotation speed sensor (hereinafter referred to as Ne sensor) 10 that detects the engine rotation speed Ne and outputs an electrical signal is located around the camshaft or crankshaft of the engine l (both of which are not shown). It is being The Ne sensor 10 outputs a pulse signal every 120 degree rotation of the crankshaft at a predetermined crank angle position, and the pulse signal is sent to the IE CU 7 as an engine rotation speed signal and a top dead center ("17Dc) signal. Man-powered.

The downstream end of the exhaust passage 3^ of the first cylinder group and the second
The downstream ends of the exhaust passages 3B of the cylinder groups merge with each other, and a three-way catalyst 11, which is a catalytic converter device, is interposed at the merged portion, thereby reducing IIC, IIC, and the like in the exhaust gas.
The purification effect of Go and NOx components is awaited. The three-way catalyst 1
．． Two oxygen sensors (hereinafter referred to as 02 sensors) 1 are installed in the exhaust passages 3^ and 3B on the upstream side of 1, respectively, to detect the concentration of oxygen (02) in the exhaust gas and output an electrical signal.
2^, 12B are provided, and these 02 sensors 12
^, The oxygen concentration detection signal output from +2e is
j,tL! ECU7G: Input rail.

The ECU 7 shapes the waveform of the input signal from the various parameter sensors and the engine operating parameter sensor 13 such as an engine temperature sensor, or corrects the voltage level of the input signal to a predetermined level, and then converts the input signal into a corrected analog signal value. an input circuit 7a having functions such as converting the signal into a digital signal 11α, and a central processing circuit (hereinafter referred to as CPU).
71), a storage means 7C for storing calculation results, etc., and an output circuit 7 for supplying drive signals to the fuel injection valves 61 to 66.
It is composed of d, etc.

The ECU 7 inputs the various signals described above and determines the valve opening time TOUT (L) of the fuel injection valves 61 to 63 of the first to third cylinders 21 to 23 of the first cylinder group and the second cylinder group. Fuel injection valves 6 for fourth to sixth cylinders 21 to 26
The valve opening times T OUT (J) of 4 to 66 are calculated using the following equations.

T out (L) = TiX KO, (L)
, +, -(2) Here, Ti is the fuel injection valve 61 to 66
This is a reference valve opening time commonly used for the engine operating conditions, and is calculated according to the engine rotational speed detection signal from the Ne sensor IO and the absolute pressure detection signal from the PB^ sensor 9, which represent the engine operating state. Furthermore, KO2(L) is the air-fuel ratio correction coefficient for the first cylinder group (first to third cylinders 21 to 23), and KO2(R) is for the second cylinder group (fourth to sixth cylinders 21 to 23).
4"-26) side, and these air-fuel ratio correction coefficients KO2 (L) and Koz (R) are the 02"-26) side air-fuel ratio correction coefficients corresponding to each cylinder group during air-fuel ratio feedback control.
They are set according to the oxygen concentrations indicated by the detection signals of the sensors 12^ and 128, respectively.

K1 and K2 are a correction coefficient and a correction variable respectively calculated according to various engine parameter signals, and are set to required values to optimize fuel consumption characteristics, exhaust gas characteristics, etc. according to engine operating conditions. Ru.

By the way, the above-mentioned air-fuel ratio correction coefficients KO2(L) and Koz(
+ is set in the air-fuel ratio feedback region of the engine according to the outputs of the 02 sensors 12^ and 12B shown in Fig. This is multiplied by Ti to correct this, and the resulting valve opening time 'our(t), 'I
According to 'o uy(t), the air-fuel ratio of the air-fuel mixture supplied to each cylinder group of the engine 1 is controlled to the stoichiometric mixture ratio (for example, 14.7) at which the conversion efficiency of the three-way catalyst 11 is maximized. Specifically, 02 sensor I2 in Cr' U7b
The output values (voltage values) representing the oxygen concentration of ^ and 12B are each compared with a predetermined reference value (for example, 0.6 volts). When the output value of the 02 sensor 12^ on the exhaust passage 3^ side changes from the rich side to the lean side or vice versa with respect to the predetermined reference value, the output value of the 02 sensor 12^ on the exhaust passage 3^ side changes from the rich side to the lean side or vice versa.
The first correction value Pi is added or subtracted to the correction coefficient KO2 (L) applied to the injection valves 61 to 63 of the first cylinder group corresponding to As far as possible, the second correction value Δk is added to or subtracted from the correction coefficient KO2(L) every time a predetermined time elapses, for example, every time the TDC signal generates a predetermined number of pulses (one-term control).

On the other hand, when the output value of the 02 sensor 12B on the exhaust passage 3B side changes from the rich side to the lean side or vice versa with respect to the predetermined reference value, the injection 064 of the second cylinder group corresponding to the 02 sensor 12B changes every time the output value changes from the rich side to the lean side or vice versa. The first correction value P i k j
] Il! , S11. (Pfn: l11n), MF
As long as Pl+'fl remains on the lean side or rich side, the second correction value Δk is increased or decreased by the correction coefficient KO2 (1 term control) every time the predetermined time elapses.

As a result, when the detection signal of the 02 sensor 12^ indicates the rich side, the ECU 7 calculates the valve opening time TOLIT( The correction coefficient 1(
The value of 02(L) is decreased to bias the air-fuel ratio of the air-fuel mixture supplied to the first cylinder group toward the lean side. On the contrary 0
When the detection signal of the second sensor 12^ indicates the lean side, the correction coefficient K is adjusted so that the valve opening time 'I'0UT(L) becomes larger.
The value of O2(L) is increased to bias the air-fuel ratio of the mixture toward the rich side.

On the other hand, when the detection signal of the 02 sensor 12B indicates the rich side, the ECU 7 detects the cylinder belonging to the second cylinder group (the fourth
The correction coefficient KO2 is set so that the valve opening time TOIJT(R) of the fuel injection valves 61 to 66 arranged in the cylinders 61 to 6) is reduced.
(R) to bias the air-fuel ratio of the air-fuel mixture supplied to the second cylinder group toward the lean side, and conversely, the 02 sensor 1
When the detection signal of 2B indicates the lean side, the valve opening time Tou
The value of the correction coefficient KO2 (1) is increased so that r(g) becomes larger, and the air-fuel ratio of the air-fuel mixture is biased towards the rich side.

The rE CU 7 is the valve opening time TOUT (L) and 1-OUT (R
) is supplied to the fuel injection valves 61 to 63 and 64 to 66 of the corresponding cylinder groups, respectively, to control the injection time (valve opening time).

Next, a method for selecting and assembling fuel injection valves according to the present invention, which is applied to the fuel injection control device and the like having the above structure, will be explained.

As mentioned above, the fuel injection + ryr control device is assembled ()
At the time of manufacture, a fuel injector that is used in a fuel injection valve is determined to be good or bad depending on whether its flow rate characteristics are within a certain standard (within the diagonal lines in FIG. 4).

However, even after it is determined that the fuel injection valve is a good product, there are still individual differences between fuel injection valves, and the influence of these individual differences on air-fuel ratio control as described above cannot be ignored. Therefore, in the present invention, fuel injection valves determined to be non-defective at the time of manufacture are further classified into a plurality of groups with similar flow characteristics, and the injection valves belonging to the same classification group are given the same identification symbol, and one 02 sensor senses 1
Only injection valves with the same identification symbol are installed in each cylinder group.

Grouping based on the flow rate characteristics of fuel injection valves will be described below.

The flow characteristics of fuel injection valves determined to be non-defective can be roughly classified into four patterns A to D shown in FIG. Tables 1 and 2 show methods for determining the above four patterns.

First, the fuel t' of the injector to be classified is determined by the actual value of the flow rate Q at a small fuel flow rate (valve opening time 2 rnsee) when the internal combustion engine is in an idling operating state. Is it between the median value Q1 at the time of small flow rate, which is the d1 target, and the l limit value (between O and +3%)? (Category ``Y'')
Or between the median value Q+ and the lower limit (0 to -3%
In addition, the actual fuel flow flQ at the time of a large fuel flow rate (opening time 24 m5ec) when the internal combustion engine is in a high-load, high-speed state is is the median value Qw at high flow rate up to the upper limit (0
-+2%) (category upper") or between the median value Qw and the lower limit (0 to -2%) (category lower") (Table 1) ).

Table-1 Table-2 Next, when the classification determined for the small flow rate (2 msec) and high flow rate (24 m5 ec) of the classified injection valve are both "upper" (pattern of solid line A in Figure 2), gives identification symbol A to the injector. - When the force is "up" when the flow rate is small, and "down" when the flow rate is large (pattern indicated by dot-dashed line B in Figure 2)
Identification symbol 13 is used for "lower" when the flow rate is small, "upper" when the flow rate is large (pattern of the two-dot broken line C in Fig. 2), and identification symbol C is used for the small flow rate and large flow rate. When it is below (
In the broken line pattern in Figure 2), identification symbols are given to the respective classified injection valves (Table 2).

Figure 3 shows that among the fuel injection valves classified using the above method, only those with the same identification symbol are installed in the fuel injection control device shown in Figure 1, and the air-fuel ratio is actually adjusted to the stoichiometric mixture ratio. 3 is a graph showing the content of exhaust gas components when feedback control is performed.

The content is expressed in terms of Nox/Co and NOx/IC relationships. The experimental results obtained by the device to which the method of the present invention is applied are plotted (◇), and the fuel injection brake r that meets certain standards at the time of manufacture was not identified and was installed in the fuel injection control device and then Similar plot of exhaust gas components when fuel ratio feedback control is performed (Δ mark)
As shown in FIG. 3, there is a large difference in the variation width. That is, when conventional air-fuel ratio control is performed using an unidentified fuel injector, points (△ marks) representing the content of exhaust gas components are scattered within the range indicated by diagonal lines in Fig. 3; The above A is attached to the cylinder sensed by one 02 sensor.
- When air-fuel ratio control is performed by installing only fuel injectors with the same identification symbol in D, the point (◇ mark) representing the exhaust gas component-containing surface will approximately be surrounded by the solid line in Figure 3. It can be seen that it converges within the range. This is because when air-fuel ratio control is performed by installing only fuel injection valves with the same identification symbol in the cylinders corresponding to the same O2 sensor, the relationship between valve opening time and fuel flow rate is similar. This is because the air-fuel ratio of the air-fuel mixture supplied to the plurality of cylinders sensed by one 02 sensor becomes the road-to-road value, which further improves the accuracy of air-fuel ratio control.

(Effects of the Invention) As detailed above, according to the present invention, a plurality of fuel injection valves intermittently inject and supply fuel to corresponding cylinders of a multi-cylinder internal combustion engine, and a plurality of fuel injection valves that intermittently inject fuel into corresponding cylinders of a multi-cylinder internal combustion engine, and an exhaust concentration detector that detects the oxygen concentration in the exhaust gas;
determining the amount of fuel supplied by the fuel injection valve corresponding to the cylinder based on the output signal from the exhaust gas concentration detector;
A method for selecting and assembling a fuel injection unit for a multi-cylinder internal combustion engine comprising a fuel injection control device for controlling an air-fuel ratio of an air-fuel mixture supplied to the cylinder to a target air-fuel ratio,
The fuel flow values of a plurality of fuel injection valves whose fuel Ft dispersion values are within a predetermined dv capacity difference range are measured at at least two points, one at a small flow rate and one at a large flow rate, and the fuel flow rate values are determined based on the measured fuel flow values. ? ') Classify the injection valves r into multiple groups, and give the same identification symbol to the fuel injection valves a and 1 belonging to the same classified group, and the same identification symbol Since only r is set in the cylinder corresponding to one exhaust concentration detection RN (by 1), the air-fuel ratio of the mixture supplied to the cylinder corresponding to one exhaust concentration detector is
Therefore, the accuracy of the air-fuel ratio control performed based on the output signal of the air concentration detection unit u1 is further improved.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the overall configuration of a multi-gas internal combustion engine to which the fuel injection valve screening method of the present invention is applied, and Figure 2 shows four patterns of flow rate characteristics of the fuel injection valve. The graph, Figure 3 is a graph comparing the exhaust gas component content of an internal combustion engine and the exhaust gas component content of a conventional internal combustion engine, and 4th rgJ represents the criteria for determining good or bad based on the flow rate characteristics of the fuel injection valve. It is a graph. 1... Internal combustion engine, 21 to 26... Cylinder, 3^,
3a...exhaust passage, 61-66...fuel injection valve,
7...Electronic control unit (ECU),]
l... Three-way catalyst, 12^, 12e... Oxygen (02)
sensor. Applicant Honda Motor Co., Ltd.

Claims (1)

[Claims] 1. A plurality of fuel injection valves that intermittently inject and supply fuel to corresponding cylinders of a multi-cylinder internal combustion engine, and an exhaust concentration detector that detects oxygen concentration in exhaust gas discharged from at least two or more cylinders. , a fuel that determines the amount of fuel to be supplied by the fuel injection valve corresponding to the cylinder based on the output signal from the exhaust gas concentration detector, and controls the air-fuel ratio of the air-fuel mixture supplied to the cylinder to a target air-fuel ratio. In a method for selecting and assembling fuel injectors for a multi-cylinder internal combustion engine equipped with an injection control device, the fuel flow values of a plurality of fuel injectors whose fuel flow values are within a predetermined tolerance range are divided into small flow rates and high flow rates. The fuel injectors are classified into a plurality of groups based on the measured fuel flow rate values, and the same identification symbol is given to the fuel injectors belonging to the same classified group to ensure the same identification. 1. A method for selecting and assembling fuel injectors for a multi-cylinder internal combustion engine, characterized in that only fuel injectors given symbols are assembled into cylinders corresponding to one exhaust gas concentration detector.