JPH0147613B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronically controlled fuel injection device that stops fuel injection when an internal combustion engine (hereinafter referred to as engine) that drives a vehicle decelerates, and in particular, relates to an electronically controlled fuel injection device that stops fuel injection when an internal combustion engine (hereinafter referred to as engine) that drives a vehicle decelerates, and in particular, The present invention relates to a device for preventing the deterioration of the drive feeling of a vehicle that occurs until then.

In the conventional configuration of the above device, a throttle sensor installed in the engine's throttle valve detects whether or not the opening of the throttle valve is below a set value. ) and the engine rotational speed is a predetermined value _N1 or higher, fuel injection to the engine is stopped, and when the throttle valve is opened to a predetermined opening or more (the idle switch is This is done when the idle switch is turned off) or when the engine rotational speed drops to a predetermined rotational speed _N1 or less while the idle switch is kept at a predetermined opening or lower (the idle switch is on).

Among the recovery conditions mentioned above, there are two ways to recover fuel supply when the engine speed drops below _N1 with the idle switch on: (i) Immediately applying a pulse width using normal calculations; (ii) ) Japanese Patent Application Publication No. 1973-
As disclosed in Publication No. 55237, when the fuel supply is restored, a pulse width that is smaller than the pulse width of the drive pulse of the fuel injection solenoid valve (hereinafter simply referred to as pulse width) based on normal calculation is applied, and the pulse width is reduced over time. There are two methods for performing so-called weight loss control at the time of fuel supply restoration, in which the weight loss value is gradually reduced and returned to the normal pulse width calculation value.

The method (i) for restoring fuel supply has the following drawbacks. That is, since normal fuel is injected immediately after the fuel injection stop is canceled, normal combustion suddenly occurs and the engine torque rapidly increases, resulting in poor drive feeling. This phenomenon is noticeable when the engine speed is low, and in order to prevent deterioration of the drive feeling, the set value of the fuel supply stop (cut) rotation speed _N1 must be set high, which reduces fuel consumption and harmful emissions. The great advantages of reducing the amount of gas released and reducing the heat load on the catalyst are diminished.

Method (ii) above is a measure taken in view of the shortcomings in (i), and is intended to improve the drive feeling during normal deceleration driving with the clutch in the on state, but it does not change the driving method or fuel supply. Cut rotation speed
Depending on the predetermined value of N ₁ , the effect may not be sufficient. According to the results of investigating the conditions at this time, when the engine resumes combustion after the fuel supply to it has been cut off, the load condition and rotational speed of the engine are often in an unstable state of fluctuation. Therefore, if we calculate the drive pulse width of the fuel injection solenoid valve by performing calculations based on such fluctuating load conditions and rotational speeds, the calculated value at that time will also vary, so Furthermore, in order to perform the reduction control when returning to fuel supply as described above, in which a reduced pulse width is given and then the reduced amount is gradually decreased over time to return to the normal pulse width calculation value, a predetermined control is performed. If the above-mentioned non-variable correction factor is multiplied, the resulting pulse width will still vary, and the engine air-fuel ratio (and therefore the engine output torque) will vary significantly, causing the vehicle to It was found that vibrations occurred in the front and rear directions, worsening the drive feeling.

From the above investigation results, it was found that it is desirable to satisfy the following two requirements when recovering from a cut in fuel supply.

(1) When returning, the air-fuel ratio is gradually returned to the normal calculated pulse width from a lean state, that is, a state where the pulse width is small.

(2) However, at this point, the normal calculation pulse width may fluctuate greatly, so in order to avoid being affected by this, instead of reducing the normal calculation pulse width by a specified amount, It is desirable to perform control using a pulse width that is programmed separately from the calculation pulse width.

In order to meet the above requirements, the present invention provides a preprogrammed magnitude independent of the engine load condition and rotational speed for the electric pulse for driving the electromagnetic fuel injection valve upon recovery from a cut in the fuel supply. Provided is an electronically controlled fuel injection device configured to provide a pulse width for a predetermined period and then return to a pulse width determined based on the load condition and rotational speed of an engine, thereby improving drive feeling. The purpose is to

The inventor of the present application previously disclosed in Japanese Patent Application No. 1982-21264 that the driving force transmission clutch is connected (turned on) when the fuel supply is cut off after detecting engine deceleration. However, in the embodiment of the present invention described below, the control method described above is a device;
An embodiment in which the present invention is combined with an improved device for controlling normal deceleration when the clutch is on will be described.

FIG. 1 shows the overall configuration of an apparatus according to an embodiment of the present invention. In FIG. 1, an engine 1 is a known four-cycle spark ignition engine mounted on an automobile, and intakes combustion air through an air cleaner 2, an intake pipe 3, and a throttle valve 4. The output of the control circuit 20 causes the electromagnetic fuel injection valve 5 to open and supply fuel to each cylinder. The exhaust gas after combustion is released into the atmosphere through the exhaust manifold 6, exhaust pipe 7, etc. Engine 1 is in intake pipe 3
A potentiometer-type intake air amount sensor 8 is installed that detects the amount of intake air taken into the engine and outputs an analog voltage corresponding to the amount of intake air. Also installed is a thermistor-type intake temperature sensor 9 that detects the temperature of intake air and outputs an analog voltage according to the intake air temperature. The engine 1 is also equipped with a thermistor-type water temperature sensor 10 that detects the coolant temperature and outputs an analog voltage according to the coolant temperature. It detects the speed and outputs a pulse signal with a frequency corresponding to the rotation speed. For example, an ignition coil of an ignition device may be used as the rotation speed sensor 11, and an ignition pulse signal from a primary terminal of the ignition coil may be used as the rotation speed signal. The throttle valve is also provided with an idle switch 12 that detects that the throttle opening is below a predetermined value. The control circuit 20 is a circuit that calculates the fuel injection amount based on the detection signals of the sensors 8 to 12, and adjusts the fuel injection amount by controlling the opening time of the electromagnetic fuel injection valve 5.

The control circuit 20 will be explained with reference to FIG.
100 is a microprocessor (CPU) that calculates the fuel injection amount. Reference numeral 101 denotes a rotation number counter that counts the engine rotation number based on a signal from the rotation speed (rotation number) sensor 11. Further, this rotation number counter 101 sends an interrupt command signal to the interrupt control section 102 in synchronization with the engine rotation. When the interrupt control unit 102 receives this signal, it interrupts the CPU 100 via the common bus 150.
Outputs an interrupt signal for. Digital input port 103 transmits digital signals such as a starter signal from starter switch 13 for turning on and off a starter (not shown) to CPU 100. The analog input port 104 consists of an analog multiplexer and an A-D converter, and has the function of converting each signal from the intake air amount sensor 8, the intake air temperature sensor 9, and the cooling water temperature sensor 10 from A to D and sequentially reading it into the CPU 100. . Each of these units 101,
The output information of 102, 103, and 104 is transmitted to the CPU 100 through the common bus 150. 10
5 is a power supply circuit, which is connected to the battery 14 through a key switch 15. 106 is a random access memory (RAM) that can be read and written. A read-only memory (ROM) 107 stores programs and various constants. Reference numeral 108 is a fuel injection time control counter including a register, which is composed of a down counter, and transmits a digital signal representing the opening time of the electromagnetic fuel injection valve 5 calculated by the CPU 100, that is, the fuel injection amount, to the actual electromagnetic fuel injection valve 5. is converted into a pulse signal with a pulse time width that gives the valve opening time.
Reference numeral 109 denotes a power boosting section that drives the electromagnetic fuel injection valve 5. 110 measures the elapsed time with a timer.
The information is transmitted to the CPU 100. Rotation number counter 101
measures the rotational speed of the engine by counting the rotation of the engine once per engine rotation based on the output of the rotational speed sensor 11, and supplies an interrupt command signal to the interrupt control section 102 at the end of the measurement. The interrupt control unit 102 generates an interrupt signal in response to the signal, and causes the CPU 100 to execute an interrupt processing routine for calculating the fuel injection amount.

FIG. 3 shows a schematic flowchart showing the arithmetic processing procedure of the CPU 100. Hereinafter, the functions of the CPU 100 will be explained with reference to this flowchart, and the operation of the entire configuration will also be explained. When the key switch 15 and starter switch 13 shown in FIG. 2 are turned on and the engine 1 is started, the first
The arithmetic processing of the main routine is started at the start of step 1000, initialization processing is executed at step 1001, and a digital value corresponding to the cooling water temperature signal from the analog input port 104 is read at step 1002. In step 1003, a fuel correction amount _K1 is calculated from the result, and the result is stored in the RAM 106. When step 1003 is completed, the step
Return to 1002. Usually, CPU100 is as shown in Figure 3.
The main routine processes 1002 to 1003 are repeatedly executed according to the control program. Interrupt control unit 1
When the interrupt signal from 02 is input, CPU10
0 immediately interrupts the main routine even if it is in progress and moves to the interrupt processing routine starting at step 1010.

In step 1011 of the interrupt processing routine, a signal representing the engine rotation speed N from the rotation number counter 101 is taken in, and then in step 1012, a signal representing the intake air amount Q is taken in from the analog input port 104. Next, in step 1013, the basic fuel injection amount (that is, the basic injection time width t of the electromagnetic fuel injection valve 5) determined from the engine speed N and the intake air amount Q is calculated. The calculation formula is t=F
×Q/N (F is a constant). Next, in step 1014, the fuel injection correction amount obtained in the main routine is
_K1 is read from the RAM 106 and a correction calculation is performed for the fuel injection amount (injection time width) obtained in step 1013. The program then proceeds to step 1015, fuel supply cut control, and then returns to the main routine via step 1016.

Next, in explaining the fuel supply cut control in step 1015, which is a feature of the present invention, a method for detecting the operating state of the engine by determining whether the deceleration during deceleration of the engine is equal to or higher than a predetermined deceleration will be described. explain.

FIG. 4 shows the course of changes in engine rotational speed when the engine decelerates. When the engine decelerates from the fuel supply cut state and the engine rotation speed N reaches the predetermined fuel supply cut rotation speed N ₁ , the fuel supply is restored, but the basic injection pulse width output immediately before the engine rotation speed drops below N ₁ (Step 1013
The engine rotation speed at the point synchronized with output) 301 is set as _No , and the pulse width 302 one position before
If the engine rotation speed synchronized with is N _o-1 , then
Deceleration (decreased rotational speed) when fuel supply is restored (△
N _o ) is expressed as N _o-1 − N _o . In the figure, the shaded area A indicates the range in which the engine rotational speed decreases during deceleration driving when the clutch is on, and the shaded area B shows the range in which the engine rotational speed decreases during racing or during deceleration driving when the clutch is off. This deceleration (△
However, when △N _c is the set deceleration (decreased rotational speed) set to correspond to the boundary line C approximately in the middle between the two, △ _{N o is} greater than or equal to △N _c By determining whether or not the engine is racing, it is possible to detect whether the engine is racing or decelerating when the clutch is off, or whether the engine is decelerating when the clutch is on. Based on this idea, regarding the flowchart in Figure 5 which actually shows step 1015 in Figure 3 in detail,
The function of step 1015 will be explained.

Step 1015 starts from fuel supply cut control inlet step 1015' in FIG. Set on the counter. If the idle switch 12 is on, the process proceeds to step 602, where it is determined whether the engine rotational speed is equal to or higher than the set fuel supply cut rotational speed _N1.If this is the case, the process passes through step 608 and proceeds to step 1016, so that fuel injection is performed. will be stopped. Also, if the fuel supply cut rotation speed is less than the set fuel supply cut rotation speed, proceed to step 603.
It is determined whether or not the occurrence of the basic fuel injection pulse obtained in step 1013 is within a set period after the return of fuel supply. It is determined each time whether the cumulative value of the elapsed rotation speed (elapsed rotation speed) is within a set value, and if it is within that period, the process proceeds to step 604, and the deceleration of the engine during the fuel supply return period for each rotation is determined. do. As a result of the determination, if the deceleration is △N _o set deceleration △N _c , it is determined that the vehicle is racing (including during deceleration driving when the clutch is off), and the process proceeds to step 605, where the amount of fuel is increased at the same time as the fuel supply is restored. In order to prevent engine stall, if △N _o < △N _c , it is determined that the vehicle is running at normal deceleration when the clutch is on, and the process proceeds to step 606 to perform the aforementioned reduction control when the fuel supply is restored. This can prevent the drive feeling from deteriorating when the fuel is restored. If it is within the set period after the fuel supply is restored and the clutch is turned off, the determination result in step 604 is △N _o △N _c
Therefore, it is possible to stop reducing the amount upon return and switch to increasing upon returning, thereby preventing engine stall. As a result of the determination in step 603, if a preset period has elapsed since the time when fuel supply was restored, the process proceeds to step 607, where it is determined whether or not the amount of fuel is being reduced at the time of recovery. If the weight is not being reduced upon return, proceed to step 608.

Next, the steps in FIG. 5, which are the features of the present invention,
The flowchart of FIG. 6 showing the details of the operation of the reduction control when the fuel supply is restored in step 606 will be explained. In FIG. 6, t _c is the fuel injection pulse width during return reduction control, and t _iot is the pulse width (initial value) of the first fuel injection pulse. Also t
is the pulse width of the fuel injection pulse applied to the solenoid valve.

Figure 6 shows 1 of the above-mentioned reduction control when returning fuel supply.
An example is shown, and in step 6061, it is determined whether or not this is the first fuel injection pulse of the return reduction control. If it is the first pulse, in step 6062, a preset reduction pulse width _tiot is given as the value of the pulse width _tc . Next, the process proceeds to step 6065, where the fuel injection pulse width calculated up to step 1014 is ignored and t _c is set as the fuel injection pulse t. In addition, if it is determined in step 6061 that it is not the first fuel injection pulse, step
In step 6063, it is determined whether the cumulative value of the engine's elapsed rotational speed (or the number of basic fuel injection pulses generated) after the return of fuel supply has reached the set value, and if the cumulative value does not reach the set value, step 6064 is performed. at t _c
A constant increment width Δt _c of pulse width increase is added to the pulse width. Thereafter, through steps 6065 and 608, the increased pulse width is set in the counter. Furthermore, if it is determined in step 6063 that the cumulative value of the elapsed rotational speed of the engine after the return of fuel supply is greater than or equal to the set value, no increase or decrease is performed and step 6063 is performed.
At step 608, the pulse width calculated in step 1014 of FIG. 3 is set as t (or another specific set pulse width _td as t) in a counter. If we look at the aspect of this control with respect to the fuel injection pulse width signal applied to the electromagnetic fuel injection valve ₅ when the fuel supply is restored as shown in _FIG . As shown, at the same time as the fuel supply is restored, the pulse width t (Fig. 7c) is determined by normal calculation.
Give a pulse width t+△t that is increased from △N _o
In the case of <△N _c , as shown in Fig. 7b, at the same time as the fuel supply is restored, a preprogrammed initial pulse width smaller than the pulse width t calculated by normal calculation is set.
First give t _iot as t _c ←t _iot , then gradually increase the normal pulse width t as t _c ←t _c +△t _c for each injection.
This shows the mode of control to restore the original state.

In addition, changes to the above embodiment can be obtained by changing the content of the determination in step 6063 in FIG. For example, the steps in Figure 3
It is possible to control whether or not to increase the pulse width by determining whether t _c has become larger than the pulse width t (or other specific set pulse width t _d ) of the normal calculation in 1014. , It is also possible to control so that when t _c becomes equal to t (or t _d ), Δt _c =0 is maintained for a certain period thereafter. Furthermore, by making Δt _c variable and making it a function of the engine rotational speed after the fuel supply is restored, it is possible to respond to various changes in the pulse width when the fuel supply is restored. It is also possible to perform control so that Δt _c =0 is maintained for a certain period of time when the rotational speed becomes equal to the set rotational speed. Furthermore, it is of course possible to apply this control regardless of the deceleration of the engine. However, in general, the reduction calculation process at the time of fuel supply restoration shown in FIG. 6 is stopped when t _c becomes equal to the normal calculation pulse width t, and then steps 1013 and 1014 in FIG. It is preferable to shift to control of the fuel injection amount using the normal calculation pulses shown in FIG. 1 from the viewpoint of vehicle driving feeling and air-fuel ratio control.

According to the present invention, when returning after fuel supply is cut off, a pulse width of a pre-programmed magnitude, which is unrelated to the engine load condition and rotational speed, is applied for a predetermined period to the electric pulse for driving the electromagnetic fuel injection valve. The result is an electronically controlled fuel injector that is adapted to return to a pulse width determined based on engine load conditions and rotational speed, thereby increasing the basic pulse width by a set amount over the prior art basic pulse width. Compared to methods that provide reduced pulse width,
The excellent effect of being able to guarantee a stable and comfortable drive feeling at all times is obtained.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a specific configuration of the control circuit shown in FIG. 1. Figure 3 shows the second
2 is a schematic flowchart showing the execution contents of the microprocessor shown in the figure. FIG. 4 is a characteristic diagram illustrating a method of detecting the operating state from the deceleration of the engine. FIG. 5 is a detailed flowchart of the fuel supply stop control step in the flowchart of FIG. 3. FIG. 6 is a detailed flowchart of step 606 of FIG. Figure 7 shows
2 is a time chart showing a pulse signal applied to an electromagnetic injection valve, which serves to explain the operation of the device according to the embodiment of the present invention. (Explanation of symbols) 1...engine, 2...air cleaner, 3...intake pipe, 4...throttle valve, 5...electromagnetic fuel injection valve, 6...exhaust manifold, 7...exhaust pipe, 8 ...Intake air amount sensor, 9
...Intake temperature sensor, 10...Water temperature sensor, 11...
...Rotational speed sensor, 12...Idle switch,
13... Starter switch, 15... Key switch, 20... Control circuit, 100... CPU, 10
6...Random access memory, 107...Read-only memory.

Claims (1)

[Scope of Claims] 1. Electromagnetic fuel that supplies fuel to an internal combustion engine for driving a vehicle by electric pulses having a pulse width determined by an electronic control device based on the load state and rotational speed of the internal combustion engine. In an electronically controlled fuel injection device that is supplied by an injection valve and stops applying the electric pulse when the internal combustion engine is decelerating, when the application of the electric pulse is resumed from the stopped state, the pulse width of the electric pulse is: a pulse width determined based on the load condition and the rotational speed of the internal combustion engine after applying a pulse width of a preprogrammed magnitude independent of the load condition and the rotational speed of the internal combustion engine for a predetermined period; An electronically controlled fuel injection device characterized by returning to 2. The electronically controlled fuel injection device according to claim 1, wherein the preprogrammed pulse width gradually increases from a small value until it reaches a predetermined value. 3. The fuel injection device according to claim 2, wherein the predetermined value is a pulse width determined based on the load state and the rotational speed of the internal combustion engine. 4. The electronically controlled fuel injection device according to claim 2 or 3, wherein the magnitude of the pulse width is maintained at the predetermined value for a predetermined period after reaching the predetermined value.