JPS62157260A - Fuel feed device - Google Patents

Abstract

PURPOSE:To improve follow-up performance of air-fuel ratio when loads change rapidly in a spark-ignition engine by estimating a throttle valve opening ratio when loads change rapidly and by reading out a basic injection pulse width from a map using the estimated value. CONSTITUTION:When engine revolutions learned from a revolution sensor 21 and throttle opening ratios are changing, a fuel feed control device 1 obtains change rates of the said quantities calculated in a CPU and a period of time from the time the information is read in to the time of an intake stroke. Using such results, opening ratios of the throttle valve 19 during the intake stroke are estimated, and using the estimates a basic injection pulse width is read out from a map stored in a ROM 8 and others to drive an injector 23 via a counter timer 4 and a driver 5. Thus, it is possible to maintain air-fuel ratios with good follow-up performance and high accuracy when loads change rapidly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fuel supply system, and particularly to a fuel supply system for a spark-ignition internal combustion engine.

[Technical Background of the Invention] It is well known that in a spark ignition internal combustion engine, it is necessary to follow sudden changes in load and supply the necessary fuel R in just the right amount. For this purpose, the fuel supply (6) must be controlled according to the engine rotation speed. Many of the recent fuel supply hot water controls use computers, and one method is to prepare a map in advance that uses engine rotation speed and throttle valve opening as parameters, and then There is a method of collecting information, reading the information from the map, and performing optimal fuel injection control. Another method employs a map using engine speed and intake pipe pressure as parameters. Figure 5 shows θ in a method (hereinafter referred to as speed/throttle method) that uses a map using engine rotation rlINc and throttle valve opening θ as parameters.
FIG. 2 is a diagram showing a -Ne map, and the conventional method will be explained using this diagram.

That is, the engine speed read at time [Ne
, if the throttle valve opening at that time is θC, then the fifth
From the map in the figure, Ne at that time.

It can be seen that the pulse width corresponding to θC is τ. However, in the case of the normal method, to save memory, τ6
The pulse widths τ11, τ12, τ21, τ22 of the predetermined reference points surrounding 6 in the above are not stored.
τ6 is obtained by performing interpolation calculation using .

Also, there are two methods for calculating the fuel injection amount: one is synchronous with the engine speed, and the other is asynchronous. Here, we will use the synchronous method as an example, and we will explain the process from the start of calculation to the start of the next calculation. The explanation will focus on one cylinder.

FIG. 6 is a diagram showing the relationship between each stroke of a four-cycle engine and calculation of fuel injection timing.

First, the calculation is started at a predetermined timing, that is, at the bottom dead center of the start of exhaust in this embodiment, the engine rotational speed Nc and the throttle valve opening degree θ are read, and the calculation is executed. The time it takes to complete the calculation is about 11118 in this example. Next, the system waits until the injection timing based on the calculation result is reached, and performs fuel injection when the predetermined timing arrives. The injected fuel evaporates in the intake pipe, is sucked into the cylinder, undergoes compression and expansion strokes, and is exhausted, but the calculation starts again at the bottom dead center of the exhaust. .

The fuel injection timing is calculated according to each cycle above,
And these calculation cycles are repeated.

[Problems in the Background Art] The conventional q method described above calculates the injection timing based on the engine speed Ne and the throttle valve opening θ read after the start of the calculation.
, θ are not handled due to changes in Ne and θ that occur after the time when θ are read. This is exactly the same in conventional methods of taking in other engine parameters.

That is, it is difficult to assemble the A/F while the throttle is suddenly closed or the Ne is suddenly changing. To deal with this, various correction means have been proposed, but these acceleration/deceleration correction means require complicated control, and it is actually difficult to satisfy all of the various complicated conditions. be.

[Object of the Invention] The present invention was made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a fuel supply device that has excellent A/F followability during sudden changes in load and has a simple correction means. There is.

[Summary of the Invention] In the present invention, when the engine rotation kN e and the throttle valve opening θ are changing, the rate of change and the time from the information reading time to the intake stroke are determined, and the results are further analyzed. The throttle valve opening degree during the suction stroke is estimated using the above-described method, and the estimated value is used to read out the basic injection pulse width from the map.

[Basic Idea of the Invention] In the present invention, the Ne and θ parameters once read at the start of calculation are changed due to changes in Ne and θ that occur between the reading time and the suction stroke. This study focuses on the fact that the parameters used in the calculations do not correspond. Figure 3 shows θ read in at the start of calculation.
6 shows how it changes thereafter in relation to each stroke of the engine.

In other words, this figure shows that if you find the rate of change of the throttle valve opening θ6 read by smell at time t, you can understand the subsequent changes, and the actual effective θ change in the intake stroke is θ. This shows that (θ 〉〉θ,)tACT tACT .

FIG. 4 is a detailed diagram showing the calculation basis. In Fig. 4, the data read last time is θn-+, the data read this time is θn, and the time from the read time 1° of the previous data to the read time C1 of the current data is 6 times, and the data read this time is The time from time t to intake stroke tz (for convenience, the center of the intake stroke) is assumed to be 6°C, and these Δt, ΔK, θr
L-1, the actual value θ from θn. It attempts to estimate ACT. The relationship in this case is shown in FIG. 4, and the following equation can be derived from the proportional relationship equation.

Here, in the engine rotation synchronization calculation method, ΔT is proportional to the engine rotation period, and if Δ[ can be regarded as approximately the center of the intake stroke, it is also proportional to the engine rotation period. Therefore, the above formula is θ = θru 10 (θn −θ躬)
...(2) nACT Note that in the fixed period calculation method of the engine rotation synchronization calculation method, there is a relationship such that ΔT=COnSt, Δincreases the engine rotation period. Since the engine rotation period is normally determined by a counter timer in order to obtain Ne, this data can be used.

[Embodiments of the invention] Examples will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a fuel supply device according to the present invention. In FIG. 1, 1 is the main body of the fuel supply system, which consists of an A/D converter 2, an arithmetic processing section 3, a counter timer 4, an injection valve driver 5, a RAM 6, a reset timer 7, a ROHF 3, and a stabilized power supply 9. There is.

Further, 10 is a battery.

Only the main parts of the internal combustion chamber are shown; the cylinder block 12
, a piston 13, a fuel chamber 14, an intake valve 15, an exhaust valve 16, an intake pipe 17, an exhaust pipe 18, a throttle valve 19, and an intake valve drive cam 20, 21 is a rotation speed detection sensor, 22 is a temperature sensor, 23 is an injector, and 24 is a throttle valve opening sensor.

The operation of the fuel supply system having the above configuration will be described next.

First, the opening of the throttle valve 19 and the engine temperature from the temperature sensor 22 are taken into the F/D converter 2 via the throttle valve opening sensor 24, where they are converted into digital data and subjected to arithmetic processing. The information is input to section 3.

Further, the engine rotation speed is also taken into the arithmetic processing unit 3 via the rotation speed detection sensor 21 .

On the other hand, the input/output data to be processed is stored in the RAH 6, and based on this data, the calculation processing unit 3 performs calculation processing according to a predetermined program (access) stored in advance in the ROH 8. .

Further, the reset timer 7 sets the timing of the ringing process (in this case, every 3 ms), and these σ calculation results drive the injection valve driver 5 via the counter timer 4, and the injector 23 injects fuel. .

FIG. 2 is a flowchart for explaining the processing contents of the arithmetic processing section.

In FIG. 2, step 21 is a process of reading the engine speed Ne, and further, step 22 is a process of reading the throttle valve opening degree θ.

Step 23 is a process of calculating the time t until the intake stroke using the read engine speed Nc.

In this case, the time up to the intake stroke will be assumed to be the center of the intake stroke, and the calculation will be explained as a rotation synchronous calculation method. Step 24 is a process for dealing with a sudden change in load after each data is read, and θ is calculated. The calculation formula in this case is, as mentioned above, θ −θ
n+(θ−θrt−1)ACT×at= This is an estimated calculation that takes into account the time Δt until the intake stroke.

θ is determined by this ringing, and in step 25, the corrected pulse width is read out using the ACT value and the engine rotational speed Ne, and further in step 26, this pulse width is output. Step 27 is the read current θ
This is a process of storing n, and it is updated sequentially each time it is read.

The series of processes described above are repeated, for example, every 3 ms by a reset timer.

In short, the counter timer 4 receives θ calculated at approximately constant intervals from the calculation processing unit 3, and when the trigger signal from the rotation speed detection sensor 21 is input,
A corrected electric pulse is output to the injection valve driver 5, and the injector 23 is driven according to this pulse width.

In the above embodiment, 1. The calculation of the measured value θ is performed using the difference between the throttle valve opening θn read at the moment and the previously read value θt1. However, it is not limited to this,
If the noise accompanying the data cannot be ignored, the data may be compared with data from a predetermined number of times before, and when the difference is greater than a certain value, the above-mentioned estimation calculation may be performed. In addition, this calculation can be performed not only by the difference, but also by a method such as using a ratio, and the estimation calculation can be applied only to either the acceleration direction or the deceleration direction. Of course it's a cylinder.

Although the above embodiment has been described as a fuel supply device, the present invention can also be applied to an electronically controlled carburetor or the like that collects information intermittently and controls the fuel supply amount for the next intake stroke.

However, the present invention cannot deal with sudden changes in load that occur during Δt.

After all, in the previous data reading stage, θn−θ
tt-1=O, therefore, the correction amount θ to n is C
This is because the T calculation cannot be performed. To prevent this, the reading period may be shortened, and the calculation method may be asynchronous and short-period calculation.

[Effects of the Invention] As explained above, according to the present invention, the parameters once read are used to correct the changes in the parameters that occur after the reading time, so that the following effects can be achieved. I can do it.

■Since fuel corresponding to the amount of intake air during sudden changes in load can be immediately injected and supplied, the air-fuel ratio formula /F can be maintained with high accuracy.

■Even if there is an intake delay due to fuel adhering to the intake passage, air-fuel ratio correction only needs to take into account the intake delay.
Since there is no need to take data reading delays into account, calculations are simplified.

(2) It is particularly effective in a system in which data is read and calculated at a period lII which is shorter than the engine rotation period (particularly a substantially constant period asynchronous to the engine rotation).

■A method with a small intake delay in which fuel is injected near the intake valve or into a high temperature area is particularly effective.

■Regarding data reading, the speed throttle method is highly effective as it requires less use of mechanically or computationally filtered data.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an embodiment of the fuel supply device according to the present invention, Fig. 2 is a flowchart explaining the processing contents of the calculation processing section, and Fig. 3 shows how the throttle valve opening degree read at the start of the calculation is Figure 4 is a detailed diagram showing the basics of total σ, and Figure 5 is a map showing the relationship between engine speed and throttle valve opening. The diagram shown above, Figure 6, is 4
FIG. 3 is a diagram showing the relationship between each stroke of a cycle engine and calculation of fuel injection timing. U...Fuel supply system body 2...To 10 Converter 3...Arithmetic processing unit 4...Power Kunta timer 5...Injection valve driver 6...RAM7...Reset timer 8... ROM9...Stabilized power supply
10...Battery 11...Internal combustion engine
12...Cylinder block 13...Piston
14...Fuel chamber 15...Intake valve
16...Exhaust valve 17...Intake pipe 1
8...Exhaust pipe 19...Throttle valve 20...
・Intake valve drive cam 21...Rotation speed detection sensor 22・
...Temperature sensor 23...Injector

Claims (3)

[Claims] (1) In a fuel supply system for a spark ignition internal combustion engine that stores information related to the operating state of the internal combustion engine in a map and determines the fuel supply amount by reading out corresponding information from the map according to the operating state, the following means is provided: A fuel supply device comprising: [1] Means for storing information related to the operating state of the engine; [2] First arithmetic means for comparing and calculating the stored information and newly collected information; [3] By the first arithmetic means. Based on the comparison result, the time interval at which the two compared pieces of information were collected, and the time interval from the collection time of the newly collected information to the intake stroke of the engine, the information at the time of the arrival of the intake stroke is calculated. a second calculation means for performing a guess calculation; [4] a means for reading information corresponding to between basic injections from the map based on the guess calculation information; (2) The fuel supply system according to claim 1, wherein the information taken in as the operating state of the engine is the engine rotational speed and the throttle valve opening. (3) The information calculated by the estimation calculation means is an amount corresponding to a pulse time width to be applied to an electrically operated fuel injection valve.
Fuel supply device as described in section.