JPS61108839A - Fuel injection control device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To improve fuel consumption as well as to suppress discharging amount of HC component in exhaust gas in speed reduction running by having the arithmetic value of fuel injection amount corrected when it is judged that reduction ratio of engine load is over a predetermined value. CONSTITUTION:An arithmetic means 5 is provided for calculating a fuel injection amount based on an output of various running condition detecting means including a pressure sensor 3 detecting intake air pipe pressure PM positioned downstream from a throttle valve 2. And a detecting means 6 for sensing a reduction ratio (that is, reduction ratio of load) from a throttle valve opening detected by a throttle sensor 4 is provided, and a judging means 7 is made to judge if the reduction ratio is over the predetermined value or not. And if the reduction ratio is over the predetermined value, the fuel injection amount calculated by a correcting means 8 is made to be corrected. The judging means 7 is provided with a timer means 7a and a judging means 7b, and correction arithmetic operation of the fuel injection amount is made in a predetermined time from the start of reduction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fuel injection control device for an electronically controlled fuel injection type internal combustion engine.

2. Description of the Related Art There is an electronically controlled fuel injection internal combustion engine that calculates a fuel injection amount according to intake pipe pressure. In this type of internal combustion engine, when the amount of fuel calculated from the intake pipe pressure is injected during transient conditions of the engine, especially during deceleration operation, the amount of fuel supplied to the engine may be larger than required due to fuel adhering to the inner wall of the intake pipe. However, the air-fuel ratio shifts to a richer value, and more harmful components are emitted in the exhaust gas, and fuel is wasted and the fuel consumption rate worsens. In order to prevent this, a technology has been proposed that detects the intake pipe pressure, which is a parameter representing the engine load, and adjusts the fuel supply amount by reducing the calculated value according to the detected pressure change rate ( For example, see Japanese Patent Application No. 56-125990).

Problems to be Solved by the Invention In the prior art described above, only a small amount of fuel is reduced during deceleration where the pressure change is small, so the effect of the low emission range cannot be expected to be that great. In order to obtain an effect with a small pressure change, it is necessary to control the pressure so that a large weight loss can be obtained even with a small pressure change. Even if there is a change, there is a possibility that the weight reduction will be carried out, resulting in deterioration of drivability.

Means for Solving the Problems In FIG. 1, reference numeral 1 denotes an intake pipe of an internal combustion engine, which is provided with a throttle valve. A pressure sensor 3 is arranged downstream of the throttle valve, and a throttle sensor 4 (another type of sensor may be used as long as it can detect the load condition of the engine) is connected to the throttle valve 2. The fuel injection control device includes a means 5 for calculating the original fuel injection amount according to engine operating conditions including the intake pipe pressure downstream of the throttle valve 2, and a means 5 for detecting the reduction rate of the throttle valve opening (i.e., the reduction rate of the load). means 6 for determining whether the detected reduction rate of the throttle valve opening is greater than or equal to a predetermined value; and means 7 for determining whether the reduction rate of the detected throttle valve opening is greater than or equal to a predetermined value; The present invention comprises a means 8 for correcting the calculated value of the fuel injection amount calculated by the above, and a means 9 for injecting the corrected amount of fuel.

The determining means 7 is comprised of a timer means 7m for detecting the time since the start of reduction in the throttle valve opening, a determining means 7b for determining whether the rate of decrease in the throttle valve opening is greater than or equal to a predetermined value, and 7c. B. For a predetermined period of time after the throttle valve opening starts decreasing, the fuel injection amount is corrected according to the engine operating conditions, and after the predetermined period of time has elapsed, the calculated fuel injection amount is directly set as the fuel injection amount.

At the time of weight reduction set by the timer means 7a
The time can be changed depending on the operating conditions.

The effective injection amount calculation means 5 calculates the fuel injection amount based on engine operating condition signals such as intake pipe pressure PM, engine speed Ne, air-fuel ratio Ox, and water temperature.

The throttle opening reduction rate detection means 6 calculates the rate of change in the opening reduction direction of the throttle valve 2 based on the signal from the throttle sensor 4. The comparison means 7b determines whether the rate of decrease in the throttle valve opening (i.e., the rate of decrease in the load) is larger than a predetermined value, and when it is determined to be large, the injection amount correction means 8 corrects the fuel injection amount calculation value. is executed. When the rate of change is smaller than a predetermined value, the modification means does not perform modification.

Further, the timer means 7a measures the time from the start of deceleration 14,
Only when it is within a predetermined time, a drive signal is sent to 7c to correct the injection amount. When the time set by the timer means 7c has elapsed, the reduction correction of the fuel injection amount is canceled even during deceleration.

In FIG. 2 of the embodiment, 20 is a cylinder block, 22 is a piston, 24 is a cylinder head, 26 is an intake valve, 28 is an exhaust valve, 30 is a combustion chamber, 32 is a spark plug, 34 is a fuel injection valve, and 36 is an intake valve. 38 is a surge tank, 40II'i throttle valve, 42 is an exhaust manifold, and 44fi distributor. Since these are well-known components of an electronically controlled fuel injection internal combustion engine, a detailed explanation of the connection relationship will be omitted. In the figure, the fuel injection valve 24 is installed near the intake valve 24 of each cylinder so as to open into the intake passage, but the idea of the present invention is not limited to this type of arrangement of the fuel injection valve. It is equally applicable to systems with only one fuel injector installed upstream of 40.

46 is an electronic control circuit that controls the operation of the fuel injection valve 34 based on operating condition signals from sensors that detect various operating conditions of the engine. In this embodiment, the control circuit 46
is configured as a microcomputer system. The control circuit 34 is a microprocessing unit (MPU).
) 48, memory (random access memory (RA)
(M), a read-only memory (ROM) 50, an input port 52, and an output port 54, which are interconnected by a path 5 and are used for exchanging instructions and data. will be held. The input port 52 receives signals from each operating condition sensor (described later) manually, and is connected to the MPU.
48 calculates the fuel injection amount according to a program stored in the memory 50, which will be described later.

A fuel injection signal as a result of the calculation is applied from the output boat 54 to the fuel injection valve 34, and fuel injection control is performed. Reference numeral 57 denotes a free run counter, which is used for timing control of fuel injection and ignition timing as is well known, but in this embodiment, it is also used as a timer for detecting the elapsed time from the start of deceleration.

As an operating condition sensor, the surge tank 38 downstream of the throttle valve 40 is connected to a pressure sensor 60 via a pressure takeoff passage 58 . The sensor is of a so-called semiconductor type, and obtains an analog signal corresponding to the intake valve pressure PM downstream of the throttle valve 40.

The throttle sensor 62 can be configured as a potentiometer connected to the valve shaft of the throttle valve 40, and can obtain an analog signal corresponding to the opening degree TAIC of the throttle valve 40. An intake air temperature sensor 63 is provided upstream of the throttle valve 40, and the sensors 63 and 64 are configured as, for example, thermistors, and can obtain signals corresponding to the intake air temperature and the engine cooling water temperature TBIIIV.

An air-fuel ratio sensor 66 is provided in the exhaust manifold 42.

Air fuel ratio sensor 66 is O! It is a sensor or lean sensor, etc., and generates an analog signal according to the air-fuel ratio Ox.

The input port 52 also connects these sensors 58°, 60.
62, 63, 64 and 66 analog signals to MPU
It has a built-in analog-to-digital converter that converts the command from 48 into a digital signal. The above analog sensors (in addition to the above) T) The beater 44 is provided with two crank angle sensors 68 and 70. The crank angle sensors 68 and 70 are configured as Hall elements that face the magnet pieces 72 and 74 fixed to the distribution shaft 44m of the distributor 44. The first crank angle sensor is, for example, 360°, which is one rotation of the distribution shaft 44a.
A signal G is generated for each CA and used as a reference/9th pulse signal. On the other hand, the second crank angle sensor 70 is connected to the second crank angle sensor 7 at every predetermined crank angle (for example, every 30'CA).
Means for calculating the rotation speed from the A4 pulse signal from 0 (either hardware or software is fine)
Equipped with: Non-volatile area of memory 50, i.e. ROM
A program for calculating the fuel injection amount and driving the fuel injection valve 34 based on the signal from the sensor and the data in the memory is stored in the . The contents of this program will be explained below using a flowchart. FIG. 3 shows a flag setting routine that indicates whether or not to reduce the fuel injection amount during deceleration. This routine is a time interrupt routine that is executed at regular time intervals (for example, 10 msec). When an interrupt start signal is applied to the MPU 4H, this routine begins execution from step 100. In step 102, the MPU 48 stores the current opening degree data of the throttle valve 40 detected by the throttle sensor 40 in the TAn area of the RAM. In step 104, this current throttle valve opening T
The throttle valve opening change rate JTAn is obtained by subtracting the throttle valve opening TAn-1 obtained when this routine was executed last time from An. Next, the process proceeds to step 108, where it is determined whether the throttle valve opening change rate ΔTAn -1 obtained when this routine was executed last time is smaller than a predetermined negative value, for example -3''. No result. means that the last time this routine was executed, there was no deceleration or one rotation.Next, the process advances to step 110, where it is determined whether the current throttle valve opening change rate is smaller than 13'.Yes. The result of the determination is 0, which indicates the start time t1 of the throttle valve opening decrease in the throttle valve opening change curve n in FIG. As is well known, the free run counter 57 is a counter whose count value shown in FIG. Setting of F is executed.As will be described later, when this flag F is "11", the fuel injection amount is reduced and corrected during deceleration, and when it is "0#", the reduction correction is not performed even during deceleration. In step 116, the throttle valve opening change rate ΔT obtained during execution of this routine, that is, in step 104 is
An is replaced with ΔTAn-1 as the previous change rate.

If the determination in step 108 is YES, it indicates that deceleration occurred when this routine was executed last time. Proceeding to step 118, the rate of change of the throttle valve opening is set to a predetermined positive value;
For example, it is determined whether the angle is 3° or more.

If the determination result is No, it is determined that the deceleration operation continues (at least the transition to acceleration operation has not yet occurred). In this case, the process advances to 120 and the value of the free run counter 57 is stored in aX. In step 121, the time T from the start of deceleration during which deceleration reduction is to be performed is calculated.

As shown in FIG. 7, the ROM stores the set value of the deceleration reduction time T with respect to the intake pipe pressure (or throttle valve opening) K, which is a representative load value. This time T is set to be longer as the intake pipe pressure is lower (closer to no-load), that is, to be slightly longer than the time from the start of deceleration to when the air-fuel mixture becomes rich. The MPU 48 performs a two-dimensional interpolation calculation for the time T corresponding to the actually measured intake pipe pressure. Incidentally, instead of calculating the deceleration reduction time T using a map as described above, a similar result can be obtained by using a constant deceleration reduction time T (for example, 1 second).

At step 122, the number n of clock pulses that overlaps with the aforementioned set time T from the start of deceleration at which the fuel injection amount is reduced is calculated. At step 123, it is determined whether C2 minus C1 is greater than a predetermined deceleration reduction conversion predetermined clock pulse number n. That is, the value of the free run counter 57 is as shown in FIG.
As shown in a), C2-CIFi monotonically increases and indicates the elapsed time from the deceleration start time tl. A No result in step 123 means that the set time T has not elapsed, and the process proceeds to 114, where the deceleration reduction execution flag F is set. Therefore, the fuel injection amount is decelerated and reduced by a fuel injection routine to be described later.

12 at time t2, which is T seconds after deceleration start time t1.
The determination in step 3 is switched to Yes, the program flows to step 126, and the deceleration reduction execution flag F is reset (see Fig. 5 (cl)). In this case, the reduction in the fuel injection amount is stopped as described later. .

When the throttle valve opening change changes to 3 degrees or more before the set time T seconds elapses from the start of deceleration operation to acceleration operation (the change in the opening degree of the throttle valve 40 in this case is shown in Fig. 5 (
(represented as the dashed line m in b)).

At step 118, the answer is Yes), and the process goes to step 126, where the flag F is reset (see the broken line in FIG. 5(c)). In this case as well, the reduction in the fuel injection amount is stopped.

A No determination result in step 110 means that the reduction rate of the throttle valve opening is not smaller than 36 both when this routine was executed last time and this time, that is, the non-deceleration state continues. In this case, the program proceeds to step 126,
The weight loss execution flag F is reset.

FIG. 4 shows the fuel injection interrupt routine. - In the case of simultaneous injection, 360° from the first crank angle sensor 68
It is activated by CA signal G, and in the case of individual cylinder injection, the first
It is activated by detecting a predetermined crank angle position of each cylinder using the G signal from the crank angle sensor and the Ne signal from the second crank angle sensor 70. 200 indicates the start of such an interrupt routine, and in step 202 the MPU
48 executes calculation processing of the fuel injection amount TAU based on various information about engine operating conditions such as intake pipe pressure PM, engine rotation aNe, 2-fuel ratio Ox, water temperature THw, intake air electric current T)fA, and throttle valve opening TA. be done. This calculation process itself is well known and is not a feature of the present invention, so a detailed explanation will be omitted. In step 204, it is determined whether the deceleration reduction time flag F obtained as a result of executing the routine shown in FIG. 3 is 1 or not.

When F is 1, it is determined that the time range is T seconds from the start of continuous deceleration shown in FIG. In this case, the process branches to Yes, and in step 206, a map calculation is performed on the deceleration correction coefficient according to the intake pipe pressure PM. In other words, the deceleration correction coefficient Kl' [as shown in Figure 6, a set value is determined in advance according to the intake pipe pressure, and such a set value is stored in the ROM.
is stored in. The MPU 48 uses a well-known two-dimensional interpolation method to calculate a deceleration reduction correction coefficient corresponding to the actual measured value of the intake pipe pressure at that time. The value of the correction coefficient is 1.0 when the intake pipe pressure is high (close to atmospheric pressure), in other words, when the throttle valve 400 opening is large, no reduction correction is performed, and as the intake pipe pressure decreases, the value becomes 1.0. That is, the throttle valve opening is set smaller as it approaches the idle opening, and the button is designed to ensure sufficient deceleration correction.

If it is determined in step 204 that F is not 1, that is, the vehicle is not in deceleration operation, the process proceeds to step 208, and the deceleration reduction correction coefficient is fixed at 1.0. Therefore, deceleration reduction is not performed.

In step 210, the product obtained by multiplying the fuel injection amount TAU calculated in step 202 by the deceleration reduction correction coefficient K obtained in step 206 is replaced with the fuel injection amount TAU. As a result, when there is deceleration correction, (K(1,0)
The calculated value of the fuel injection amount becomes smaller than the value calculated in 202 by that amount. In the next step 212, fuel injection processing is executed. That is, as is well known, in this step 212, the fuel injection base distance corresponding to the fuel injection amount TAU (deceleration correction flow) is calculated, and the value obtained by adding the free run counter value at that time to this calculation time is calculated on the conveyor (not shown). is set in the register, and at the same time, the injection operation of the fuel injection valve 34 is started, and when the set value of the conveyor register and the value of the free run counter match, that is, when the amount of fuel calculated in 210 is injected, the fuel injection valve 34 is stopped and
Injection ends.

Effects of the Invention According to the present invention, deceleration reduction is executed when the rate of decrease in load represented by the rate of decrease in the opening of the throttle valve is equal to or greater than a predetermined value. Therefore, even if the deceleration reduction is performed during steady operation where the rate of load reduction is small and the pressure change is small, a sufficient amount of deceleration reduction can be performed if it is determined that deceleration is occurring.

Therefore, the amount of harmful components, especially KHC components, in the exhaust gas during deceleration driving can be suppressed without sacrificing the driving performance during steady driving, and the fuel consumption rate can be improved. .

In the embodiment, the rate of change in load is determined based on the change in opening of the throttle valve, but it is also within the scope of the present invention to detect the rate of change in load based on other factors, such as the rate of change in intake pipe pressure. .

Further, although the embodiment uses a free run counter to measure the time from the start of deceleration, it is of course possible to use an independent software or hardware counter.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of the present invention. FIG. 2 is a configuration diagram of an embodiment of the present invention. FIGS. 3 and 4 are flowcharts showing programs for realizing the control of the present invention. FIG. 5 is a diagram showing an operation timing chart of the present invention. FIG. 6 is a graph showing the setting value of the deceleration reduction correction coefficient with respect to the intake pipe pressure. Figure 7 shows the reduction time T from the start of deceleration relative to the intake pipe pressure.
The figure which shows the setting value of. 34... Fuel injection valve, 40... Throttle valve, 46
...Control circuit, 60...Pressure sensor, 62...
throttle sensor.

Claims (1)

[Claims] 1. Means for calculating the fuel injection amount according to the engine operating conditions including the intake pipe pressure downstream of the throttle valve; Means for detecting the rate of decrease in the engine load; means for determining whether or not the reduction rate is greater than or equal to a predetermined value; and in response to a signal from the determination means, when the load reduction rate is greater than or equal to the predetermined value, the calculated value of the fuel injection amount calculated by the injection amount calculation means is corrected. 1. A fuel injection control system for an internal combustion engine, comprising means for injecting a modified amount of fuel; and means for injecting a modified amount of fuel. 2. The determining means includes a timer means for detecting the time since the start of load reduction, a means for determining whether the rate of load reduction is greater than or equal to a predetermined value, and a gate, and the engine is stopped for a predetermined time from the start of load reduction. 2. The fuel injection control device according to claim 1, wherein the fuel injection amount is corrected according to operating conditions, and after a predetermined period of time has elapsed, the calculated fuel injection amount is directly set as the fuel injection amount. 3. The fuel injection control device according to claim 2, wherein the predetermined time is determined according to engine operating conditions.