JPS62197652A - Injector flow rate compensation device - Google Patents

Abstract

PURPOSE:To enhance accuracy of error compensation of fuel injection rate by obtaining error of injected fuel against a target value, and calculating a compensation value for compensating a flow rate error by learning flow rate errors at three or more representative points of specified fuel injection times. CONSTITUTION:Arranging fuel flow meters 54A-54D in fuel passages from a delivery pipe 34 connected with a fuel pump to respective injectors 22A-22D arranged corresponding to respective cylinders, outputs of the fuel flow meters are inputted together with output signals of other operating condition signals into an ECU 40. The ECU 40, while obtaining fuel injection times according to operating conditions, detects fuel flow rate errors against a target value at the time of fuel injection and learns the detected flow rate errors at three or more representative points of specified fuel injection times to calculate a compensation value for compensating the flow rate errors. Then the fuel injection time, namely the fuel flow rate, is compensated based on the compensation value.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an injector flow rate correction device, and is particularly suitable for use in an electronic fuel injection control device included in a vehicle engine, and is suitable for use in an electronic fuel injection control device installed in a vehicle engine. The present invention relates to an injector flow rate correction device that is included in a fuel injection control device that controls fuel and corrects a flow rate error of the injected fuel.

[Background Art 1] Recently, in order to solve air pollution problems and improve fuel consumption, electronic fuel injection control II devices have been introduced and are installed in passenger car engines. Note that the fuel injection control device has a simultaneous injection system that simultaneously injects fuel from the injectors of each cylinder of the engine. There are the l'J type, the group injection type in which each injector is divided into groups and injected for each group, and the independent injection type in which each injector injects fuel independently. The electronic fuel injection control device generally controls fuel injected from an injector into an intake manifold of an engine so that air intake into the engine has a predetermined air-fuel ratio. At this time, the control of the fuel injected from the injector is controlled by the opening/closing time of a solenoid valve provided within the injector. And, the 02 installed in the exhaust manifold that passes the engine exhaust gas
Based on the sensor signal, the fuel injection Q4ffi is corrected so that the air-fuel mixture has an appropriate air-fuel ratio. [Problems to be Solved by the Invention] However, when the electronic fuel injection control device corrects the fuel injection M as described above, depending on how the 02 sensor is attached to the exhaust manifold,
The detected 02 (oxygen) ton is affected only by the exhaust from a specific cylinder or multiple cylinders, and it is determined that the average air-fuel ratio of the golden cylinder is the stoichiometric air-fuel ratio based only on the information of this specific cylinder. There are cases where this happens. Further, the injector used in the electronic fuel injection control device may have an injected fuel flow rate error of about ±3%, or in some cases ±8%, due to manufacturing tolerances. In addition to errors due to such manufacturing tolerances, since the injector is opened by a solenoid valve, the injector has a flow rate characteristic as shown in FIG. 7 with respect to the injector opening time. This is not shown by the solid line in the figure and is different from the design value, so the part shown by the diagonal line in the figure is the error. Note that this error M differs depending on each injector. If the fuel injection n from the injector varies in this way, the <02 sensor will be strongly influenced by the richness or leanness of a particular cylinder due to the distribution between the cylinders. Then, even if it is determined that the intake air-fuel ratio is the stoichiometric air-fuel ratio based on the detected value of the 02 sensor affected by the exhaust from that particular cylinder, the total air-fuel ratio is actually less than the stoichiometric air-fuel ratio. It may deviate from the fuel ratio. In this case, there is a problem in that the purification performance of, for example, a three-way catalyst provided downstream of the exhaust manifold deteriorates, and the components of the exhaust gas discharged through the catalyst may deteriorate. In order to solve such problems, it is conceivable to detect the error between the fuel flow rate actually injected from the injector and the target fuel flow rate, and perform correction based on the detected error. In such a method, the injection time of the injector is divided into several regions at equal intervals, the error is learned for each region, a correction value is obtained, and the injection time is corrected in one correction shift. There are possible ways. However, if the injection time of the injector is divided into equal intervals, for example, the injection time of 3Qmsec is 1m
In particular, the independent injection type fuel injection control 7+1 features a learning area of at least 30 words even if divided into seconds.
The device further requires a memory whose number of words corresponds to the number of cylinders, which requires a significant amount of memory area, which may limit the use of the memory area for other purposes. Therefore, it is considered impractical to implement the method on an actual engine. Furthermore, as can be understood from Fig. 7, in the section where the injector valve opening time, that is, the fuel injection time is short, even a slight change in the injection time causes a large change in the error, while in the section where the injection time is long. The fluctuation is small even when the injection m changes by about 1 m5ec. Therefore, there is a problem in that learning the injection time by dividing it into equal intervals is not appropriate for learning the actual misplacement of the injector's jet 9Am.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned conventional problems, and it eliminates errors in the amount of fuel (injection) from the injectors of each cylinder without using the memory of a storage device, and improves the air-fuel ratio. It is an object of the present invention to provide an injector diversion correction device that can improve out-of-control conditions.

[Means for Solving the Problems] The present invention is provided in a fuel injection control device that intelligently controls the fuel injected from one or more injectors provided for each cylinder of an engine. An injector flow path correction device for correcting a flow rate error, which includes a fuel waterfall detection means for detecting the flow rate of the injected fuel, and a fuel flow path detection means that detects the flow rate of the injected fuel, and detects the injection flow rate based on the difference between the detected fuel flow peak and the target fuel flow peak at the time of injection. means for detecting a fuel flow rate error; means for calculating a correction value for correcting the flow rate error by learning the detected flow rate error for a specific fuel injection time using three or more representative points; Based on the correction value, the flow rate of fuel injected from the injector is corrected. The above object has been achieved by providing means for. [Operation] In the present invention, one
When correcting the flow rate error of the injected fuel of the fuel injection control device that controls the fuel injected from more than one injector,
The flow rate of the injected fuel is detected, the flow rate error of the injected fuel is detected from the difference between the detected fuel flow peak and the target fuel flow rate at the time of injection, and the detected flow ff! for a specific fuel injection time is detected. For example, as shown in Figure 1 below, the error is learned at three or more representative points for the injector valve opening time, and a correction value for correcting the flow rate error is calculated. Based on the correction value, the flow rate of fuel injected from the injector is corrected. Therefore, it is possible to eliminate errors in the flow rate of the injected fuel without using a large amount of memory in the storage device, and improve the controllability of the air-fuel ratio, so that the overall air-fuel ratio of the engine can be brought closer to, for example, the stoichiometric air-fuel ratio. be able to.

【Example】

Embodiments of the injector flow rate correction device according to the present invention will be described in detail below. In this embodiment, as shown in FIG. 2, injectors 22A to 2 provided in each cylinder are connected from a delivery pipe 34
This is an injector flow rate correction device that corrects a flow rate error of injected fuel in a fuel injection device that injects fuel from 2D. FIG. 3 shows the overall configuration of a fuel jl rAi+10il device in which the injectors 22A to 22D are provided in the manifold of the engine 10. This fuel injection control device is installed in the intake and exhaust systems of the engine 10, as shown in FIG. This intake system includes an air cleaner 12 for removing dish dust from the air sucked into the engine 10, and an air cleaner 12 for removing dust from the air sucked into the engine 10.
an air flow meter 14 that detects the flow rate of air that has passed through the air cleaner 12; a throttle valve 15 that adjusts the flow rate of the suction air (intake air); a throttle body 16 for supporting the engine, a surge tank 18 for removing pulsation during intake, and a surge tank 1
The engine 10 includes an intake valve 20 that controls intake air flowing out from the engine 8 into the cylinder 24 of the engine 10. An intake temperature sensor 38 for detecting the temperature of intake air is provided near the air flow meter 14. Further, the throttle body is provided with a throttle position sensor 42 that detects the opening degree of the throttle valve 15. In the intake manifold 13 near the intake valve 20 person side,
Injectors 22A to 22D shown in FIG. 2 are provided for each fuel. The delivery pipe 34 for distributing fuel to the injectors 22A to 22D includes a fuel tank (fuel tank) to allow the fuel to flow therein.
A fuel pump (not shown) for pressure-feeding fuel inside the fuel tank (not shown) is connected via a pipe. The exhaust side of the engine 10 is provided with an exhaust manifold 28 for flowing exhaust gas into a muffler or the like via an exhaust valve 26.
An O2 sensor 58 is installed to detect oxygen in the exhaust gas. J5, the engine 10 is equipped with a crank angle sensor 6o for detecting its crank angle. Further, detection signals from these sensors are input to a control computer (ECU) 40 that controls the operating state of the engine. Here, the injector 22 is removed from the delivery pipe 34.
As shown in FIGS. 2 and 3, each of the fuel passages A to 22D is equipped with fuel flow meters 54A to 540 that detect the flow of fuel flowing therethrough. Further, a pulsation damper 52 is provided on the fuel inlet side of the delivery vibe 34 for absorbing pulsation present in the fuel sent from the fuel pump. Furthermore, in order to keep the fuel pressure therein constant, the delivery vibe 34 is equipped with a pressure regulator 36 that returns the fuel to the fuel tank when the pressure exceeds a predetermined value. Although not shown, each of the injectors 22A to 22D has a solenoid coil that drives an on-off valve for injecting fuel into the injector by an on-off instruction pulse. Further, although FIG. 2 shows an example of an injector used in a four-cylinder engine, six injectors are required when used in a six-cylinder engine. The installation location of the flowmeters 54A to 54D is not necessarily limited to the fuel passage, but can be installed at each of the injectors 22A to 22D. Further, as the flowmeters 54A to 54D, a gear type type (detects the body flow) or a hot wire type (detects the quality flow) can be used. Note that the measurement accuracy of flowmeters using hot wires can be improved by temperature correction. Next, FIG. 4 shows the internal structure of the EC1J40. As shown in the figure, this EC1J40 includes an A/D converter 62 that converts analog signals from each sensor into digital signals, and an I10 port 6 that controls input and output of control signals.
4, a central processing unit (CPU) 66 that performs calculations based on input signals and outputs control signals, and storage devices 68A and 68B for storing information used by the central processing unit 66.
and a permanent storage device 70 capable of storing programs used in the solid device 66. The storage devices 68A and 68B are freely readable and ♂
A RAM (Random Access Memory) that can be programmed can be used. Moreover, regarding the storage device 68A,
Since the power source is backed up by a battery installed in the vehicle, the information stored therein is not erased even if the ignition switch is turned off. Furthermore, a ROM (read only memory) can be used as the storage device 70. This ROM is a read-only memory whose stored contents are maintained even without power backup. The effects of the embodiment will be explained below. In FIG. 3, the air sucked from the outside into the cylinder 24 of the engine 10 is first cleaned of dust contained therein by the air cleaner 12. As shown in FIG. Air cleaner 12
When the air that has passed through flows into the intake manifold 13, its flow rate is detected by the air meter 14. The air in which the flow has been detected flows into the surge tank 18 after passing through a throttle body 16 equipped with a throttle valve 15 for adjusting the flow. Air flowing out of the surge tank 18 flows into the cylinder of the engine 10 by opening and closing the intake valves 20 of each cylinder. At this time, fuel is injected into the intake air (intake air) from the injector 22 of each cylinder, and the cylinder 24 is filled with a mixture of fuel and air. The filled air-fuel mixture is ignited and exploded in the cylinder 24 to provide driving force to the engine 10, and then passes through the exhaust valve 26 and flows into the exhaust manifold 28. This exhaust manifold 28 is for discharging exhaust gas into the outside air via a muffler or the like. Further, in order to cause the fuel to flow into the injectors 22A to 22D, a fuel pump (not shown) pumps fuel in a fuel tank (not shown). The pressure-fed fuel flows into a delivery vibe 34 for distributing fuel to injectors 22A to 22D provided for each cylinder. The fuel in this delivery vibe 34 is controlled by the pressure regulator 36.
The fuel pressure is maintained so as to be higher than the pressure inside the surge tank 18 by a predetermined pressure. The temperature detected by the intake air temperature sensor 38 provided near the air flow meter 14 is input to the ECU 40 in the same way as the amount of air detected by the air flow meter 14 . Further, the opening degree of the throttle of the throttle body 16 is detected by the throttle position sensor 42 and inputted to the ECU 40. Further, the temperature of the engine cooling water is detected by a water temperature sensor 44. The ignition timing of a spark plug (not shown) is calculated in the ECIJ 40 based on a signal from a crank angle sensor 60 built into the distributor 80, and a signal is output to the spark plug through an ignition coil (not shown). controlled by ' In the electronic fuel injection control device in which the injector 22 is provided in each cylinder as described above, the ECU 40 controls the air flow meter 1 provided in the intake manifold 13.
Based on the signal from 4, the fuel injection time (if the fuel pressure is constant, the fuel injection M is proportional to the injection time) for controlling the amount of fuel injection from the injector 22 is determined. However, due to manufacturing errors and electrical characteristics caused by the solenoid inside the injector, the injector generally has the flow rate characteristics shown by the broken line in FIG. 7 or FIG. 1. This flow rate characteristic is different from the injection gA amount based on the design value shown by the solid line in the figure, and the difference between these values, which is the shaded part in FIG. 7, becomes an error. This error m differs depending on each injector, and it is necessary to take these errors into consideration when determining the fuel injection time. Therefore, as shown in FIG. 1, this error is measured at three or more specific representative points during the injection period of the injector, and a correction value is calculated based on the measured error. This specific representative point usually has a certain minute section, and the error measured in this section is stored in the memory device ff168A as the error of the injection m at the center of that section. When the injection time is outside the injection period at these specific points, interpolation is performed using the error due to the injection period at these specific representative points to obtain a correction value for the error. How to obtain these correction values will be explained below. That is, for example, the measurement point of the error is determined by the TAU o during the injection period of the injector, as shown in FIG.
"TALI t, TAU 2~TALJ 3,・"
, n/2 points from TAtJn-+ to TAUn. The error TAUHOi at each point is the fuel flow meter 54A to 54D.
Calculate using the following equation (1) from the integrated value (■) of the fuel flow rate measured in . TAUH5i-TALI V/α ・・・・・・(1
) However, the subscript i represents the measurement point, and TAtJ is the fuel injection time of the injector. Further, in the case of independent injection, α is the injection amount per unit injection time, and in the case of simultaneous injection, α is (injection m per unit time)*number of cylinders. The error T A tJ HO+ obtained by the equation (1) is stored in the storage device 68A, and the stored value is converted into the following equation (2
) to update. +TAtJHOiday)/2...(2)However, 1ha TAUH
Oi A is the current error value, and TAUHO+day is the previous error value stored in the storage device 68A. For the error TAUHO+ obtained in this way, correction of the injector injection time at injection times other than the specific injection CAI+I1 period measured as described above is as follows: TALI<TAtJ o and TALJ>T
Under conditions other than AUn, the target injection time TAU is calculated by the following equation (3). TAU-TAU+ [(TAUHO;ya1-TAUHO
+ ) * (TAU − (TAU2 i + TAIJ 2Hi + )/2
)] /((TAU2 crowns (ill) +TAUz4 (ill)+ 1)/2-(TALJt
(i+TAtJ 2 sehi i + 1
)/2)+TAUHOt ・-・-・l) Also, when the fuel injection time is in the period of TALI<TAUo and TAU>TAUo, interpolation cannot be performed as in equation (3), so
Periods TALIo-TAL11 and TAL+2~T, respectively
Regarding the error of ALJ3, the following equation (4) shows that the period TALJ
n-3~TAtJn-2 and T A LJ 11-1~T
The error in ALIn is estimated using the following equation (5). TAU-TALJ+ [(TAUHO chant-TALIHO
o ):l: (TAU(TAU o +TAU 1
) / 2 ) ] / ((TAU 2 + TALI
s ) / 2(T A U o + T A U +
) / 2)+TAIJHOo −・”・
...(4) T A tJ = T A tJ + [(
T A IJ HOn /2-TΔUHOtn-+t/
'z) * (TAIJ (TALI n -z+TAUn
-3>/2) ] / ((TAU n +TAL, In-+) / 2-
(TALIn-z+TAUn-3)/2) + T AU HO(n-+zo2-(5
) Next, the control of the injector flow rate correction device according to this embodiment will be explained based on the chart 70 shown in FIG. If the determination result is positive, the process proceeds to step 110, and the fuel injection time TALJ of the injector is calculated.Then, the process proceeds to step 120, and the measurement point is indicated at the index indicating each injection time TALJo-TAIJn. The index i is cleared, and in step 130 it is determined whether the injection time TAtJ is smaller than each injection time TAUk corresponding to the index k.If the determination result is positive, that is, the injection time TAU is T
Step 2 if AUo or below and TAL+2 or below
00, and also when it is determined in the previous step 100 that it is not the injection timing, the process proceeds to step 200, and the error TALJH is calculated using the above equation (4) as the index i-Q.
Calculate Oi. If the determination result in step 130 is negative, step 14
0, the index k is incremented, and the process proceeds to step 150, where it is again determined whether the injection time TAU is smaller than the measurement time TALI k corresponding to the index. If the determination result is positive, the process proceeds to step 200. If the determination result in step 150 is negative, step 160
, the index i is incremented by 1, and in step 170 it is determined whether the index k is greater than n. If the determination result is negative, the process returns to step 140 and the index k is incremented again. If the determination result is positive, the injection time TAtJ of the injector is equal to or greater than the measurement point, so the process proceeds to step 190, and by substituting (n-2)/2 for the index i, the equation (5) is calculated in step 200. A correction calculation of the injection time TAU is performed. Based on the calculated injection time TAU, step 2
At step 10, the injector is instructed to start injection. Then, proceed to step 220. In steps 220 to 260, index 1 is determined in order to update the value of error TAtJHO1. That is, in step 220, indexes i and k are cleared, and in step 2
At step 30, it is determined whether the injection time TAIJ is smaller than the measurement time TAUk, and if the determination result is no, step 2
At step 40, the index k is incremented by 1, and at step 250, the injection time TAtJ is again measured at f! 5IT
It is determined whether or not it is smaller than ALlk, and if the determination result is negative (in step 260, the index kSi is incremented and the process returns to step 230. If the determination result in step 250 is positive, the process proceeds to step 270, and the process described above ( 1)
The error TAUHOi is calculated based on the equation (2), the stored value is updated using the equation (2), and the process ends. In the above embodiment, the amount of fuel gA from each injector 22A to 220 was determined using fuel flowmeters 54A to 54D provided in each injector 22A to 22D as shown in FIG. The installation location of the meter and the measuring method thereof are not limited to this. For example, as shown in FIG. 6, fuel flow meters 54A,
11r from injectors 22A to 22D with 54B
It is possible to detect the flow rate of injected fuel with a simple configuration. Furthermore, in the embodiment described above, since the interpolation method was used to determine the fuel injection amount in sections other than the measurement points, the number of words required for the learning area in the memory of the storage devices 68A and 68B is significantly reduced. In addition, it is possible to improve the measurement accuracy by selecting a learning area that is small for areas where the injection amount is small and appropriately large for areas where the injection amount is large. However, the method for determining the fuel injection amount at points other than the measurement points is (3
), is not limited to interpolation methods such as equation (4),
It is also possible to use other methods. Further, in the above embodiment, measurements were made at n/2 points in the measurement section, but the number of measurement points in the measurement section is not limited to this, and may be at least 3 points or more. In that case, the measurement range of the injector valve opening time, that is, the fuel injection time is usually 1.5 to 2 m near the beginning of opening.
At 5ec, corresponding to low load, τ = 2.5 to 3m
It is desirable to measure at 5 ec and at τ = 5 msec, which corresponds to a medium load. This is the fuel DJ of the injector as shown in Figs. 1 and 7.
This is because the error in m is large where the valve opening time is short.

【Effect of the invention】

As explained above, according to the present invention, the error of Q4tri for fuel from the injector is stored in the memory device to a large fH
It is possible to make accurate corrections without using it. Therefore, J! for fuel from each cylinder's injector! i
It is possible to control the '+' with high precision, improve the controllability of the engine's air-fuel ratio, improve the fuel consumption rate, driving performance, etc., and also improve the performance of the exhaust gas purification device. It shows excellent effects such as being able to do things.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the relationship between the injector valve opening time and the fuel injection rate, for explaining the operation of the embodiment of the injector diversion correction device according to the present invention, and FIG.
FIG. 3 is a piping diagram showing an example of the configuration around the injector of the embodiment described above; FIG. FIG. 4 shows the control computer (EC) in the above embodiment.
FIG. 5 is a block diagram showing the internal configuration of U), and FIG. 5 is a flowchart showing the control procedure of the fuel injection control device, and FIG.
FIG. 7 is a diagram showing an example of the relationship between the valve opening time of the injector and the fuel Q1)). DESCRIPTION OF SYMBOLS 10... Engine, 13... Intake manifold, 14... Air 70-meter, 16... Throttle body, 22.22△~22D... Injector, 28...
Exhaust manifold, 34... Delivery pipe, 36... Pressure regulator, 38... Intake temperature sensor, 40... Control computer (ECU), 54Δ~54
D...Fuel flow meter, 62...△/D converter, 64...110 boat,
66...Central processing unit (CPtJ), 68Δ, 68B
...Storage device (RAM), 70...Storage device (RO
M).

Claims (1)

[Claims] (1) An injector flow rate correction device for correcting a flow rate error of the injected fuel, which is included in a fuel injection control device that controls fuel injected from one or more injectors provided for each cylinder of an engine. A fuel flow rate detection means for detecting the flow rate of the injected fuel; a means for detecting a flow rate error of the injected fuel from a difference between the detected fuel flow rate and the target fuel flow rate at the time of injection; means for calculating a correction value for correcting the flow rate error by learning the detected flow rate error with respect to the injection time using three or more representative points; and a means for calculating a correction value for correcting the flow rate error; An injector flow rate correction device comprising: means for correcting;