JPS61201855A - Electronic control fuel injecting device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To enoughly ensure an operation region in which preference is given an output even on a highland, by a method wherein mixing ratio correcting factors, respectively referred from setting means for lowlands and highlands, are compared with each other, and a fuel increase amount is corrected by means of the higher correcting factor. CONSTITUTION:In a control unit 13, a fundamental injection quantity is computed from an intake air flow rate and the rotation speed of an engine obtained by means of signals from a heat rays type flow meter 5 and a crank angle sensor 7. Based on the fundamental injection quantity a nd the rotation speed of an engine, a mixing ratio correcting factor for lowlands is referred frm a three-dimentional map stored in a memory. Based on the opening of a throttle valve and the rotation speed of an engine by means of a signal from a throttle sensor 6, a mixing ratio correcting factor for highlands is referred from a three- dimentional map stored in a memory. The two mixing ratio correcting factors are compared with each other, and the higher correcting factor and various increase correcting factors are added to determine an overall correcting factor.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and in particular, measures to improve output characteristics at high altitudes in a device that uses a hot wire flow meter for detecting intake air flow rate. Regarding.

<Prior Art> In an internal combustion engine equipped with an electronically controlled fuel injection device, the injection amount T1 is determined by the following equation.

T+ = TpX COE F xα+T.

Here, T is the basic injection amount, T p ” K X Q / N. K is a constant, Q is the intake flow rate, and N is the engine speed. =
1 + Kyw + KAS+ KAl+, KMl. Here, KtW is the water temperature increase correction coefficient I, KAS is the start and post-start increase correction coefficient r, and KAI is after idling.
・Increase correction coefficient, ll is the mixture ratio correction coefficient. α
Is the air-fuel ratio feedback system described later? This is an air-fuel ratio feedback correction coefficient for III (λ control). T is a voltage correction amount, which is used to correct changes in injection characteristics due to fluctuations in battery voltage.

During normal steady operation, feedback control of the air-fuel ratio is performed. This involves installing an O2 sensor in the exhaust system to detect the actual air-fuel ratio, determining whether the air-fuel ratio is richer or leaner than the stoichiometric air-fuel ratio based on the slice level, and controlling the fuel injection amount to maintain the stoichiometric air-fuel ratio. Therefore, the aforementioned air-fuel ratio feedback correction coefficient α is determined, and by changing this α, the stoichiometric air-fuel ratio is maintained.

In addition, during high-load operation such as acceleration, the air-fuel ratio feedback control is stopped by fixing it to α-1, and the mixture ratio correction coefficient is set to a large value to increase the fuel injection amount to improve output. (Patent application 160492/1982)
(see issue).

By the way, in recent years, as a flow meter for the intake flow rate Q, a hot wire resistor made of platinum or the like is disposed in the intake passage, and the hot wire resistance is adjusted to keep the resistance value of the hot wire resistance constant, which tends to change due to changes in the intake flow rate. There is a hot-wire flow meter that controls the value of the current flowing into the bridge circuit and detects the intake flow rate corresponding to this current value (Utility Application 1983-
(See No. 022418).

If such a hot wire flowmeter is used, the intake air flow rate can be detected by mass, so there is an advantage that a fuel amount corresponding to the true oxygen amount can be supplied and good air-fuel ratio control can be performed.

<Problems to be Solved by the Invention> Conventionally, in such an electronically controlled fuel injection device, an operating range (i.e. KMR>0) in which fuel increase correction is performed using the mixture ratio correction coefficient KHN and a mixture ratio correction coefficient in the operating range Basic injection using the KMR value as the load condition! ! kTI
- is set as a three-dimensional map corresponding to the engine rotational speed N, and fuel increase correction is performed based on the KMI retrieved from the map.

However, since the map is set based on a lowland, a hot wire type flow meter detects the intake air flow rate by mass as described above, which causes problems as described below.

In other words, when the air density decreases at high altitudes, the intake flow rate ('!) Q relative to the amount of depression of the accelerator pedal becomes smaller than at low altitudes, so the ratio of air-fuel ratio feedback control to the entire driving range increases. On the other hand, the basic injection amount T depends on the intake air flow rate Q.

Based on this, the operating range such as acceleration that requires fuel increase correction is relatively reduced. Particularly at extremely high altitudes, only air-fuel ratio feedback control is performed in almost all driving ranges, and this can result in a delay in acceleration due to fuel increase, or in extreme cases, it may not be possible to make fuel increase correction at all during acceleration, and when overtaking. poses a safety problem.

The present invention has been made in view of the above-mentioned circumstances, and uses an electronically controlled fuel injection system using a hot-wire flowmeter to ensure high-precision air-fuel ratio control at low altitudes as in conventional systems, while also providing fuel increase correction at high altitudes. The purpose is to ensure a sufficient operating range where output is given priority.

Therefore, as shown in FIG. Basic injection ffi of fuel injected from the fuel injection valve E provided in the intake passage B based on the Q signal and the engine rotation speed N signal from the engine rotation speed detection means
Electronic control of an internal combustion engine, comprising a basic injection amount setting means F for setting Tr, and an injection amount increase correction means G for increasing the fuel injection amount by multiplying the basic injection amount T by a mixture ratio correction coefficient. In the fuel injection system, an operating region in which fuel increase correction is performed in lowlands based on the basic injection amount TP and engine rotational speed N as engine load conditions, and a lowland mixture in which a mixture ratio correction coefficient KMRLO value in the operating region is set. A ratio correction coefficient setting means H, a means J for detecting the opening degree θ of the throttle valve I installed in the intake passage B, and a high altitude A high-altitude mixture ratio correction coefficient setting means for setting a value of □ and 1 for the fuel increase correction coefficient in the operating region and the mixture ratio correction coefficient in the operating region, a low-altitude mixture ratio correction coefficient setting means H and a high-altitude mixing Ratio correction coefficient setting means K
The configuration is provided with means for comparing the mixture ratio correction coefficients respectively searched from and selecting the larger mixture ratio correction coefficient.

This configuration is possible because the basic injection amount TP relative to the throttle valve opening θ increases relatively in lowlands where the air density is large, so the lowland mixture ratio correction coefficient is set using TP as a load condition. Mixing ratio correction coefficient for high altitude K MRll
The K MAL becomes larger and is used to perform highly accurate air-fuel ratio control based on the mass intake flow rate as in the past.

Conversely, at high altitudes, the basic injection amount relative to the throttle valve opening θ decreases due to a decrease in air density, so the high altitude mixture ratio correction coefficient K is set with θ as the load condition. Since H is larger than the lowland mixture ratio correction coefficient K MRL, □ and l are used, thereby ensuring fuel increase correction in driving ranges where high output is required, improving acceleration performance, etc. improves.

<Example> The present invention will be explained in detail below.

In FIG. 2 showing one embodiment, an intake passage-2 of an internal combustion engine 1 includes a fuel injection valve 3. A hot wire flow meter 5 is provided in the throttle chamber upstream of the throttle valve 4°. The spindle of the throttle valve 4 has
A throttle sensor 6 is provided to detect the opening degree θ of the throttle valve 4. Further, a crank angle sensor 7 is provided near the crankshaft of the engine 1 to detect the engine rotation speed, a water temperature sensor 8 is provided in the water jacket portion to detect the cooling water temperature, and an exhaust passage 9 is provided with a water temperature sensor 8 for detecting the cooling water temperature. An 02 sensor 10 is provided for detecting the oxygen concentration.

Signals from these various sensors, signals from the start switch 11, and voltage signals from the buffer battery 12 are input to a control unit 13 containing a microcomputer.

Based on these input signals, the control unit 13 outputs a drive pulse large signal having a pulse width corresponding to the fuel injection amount set according to the program shown in FIG. 3 to the drive circuit 14 to drive the fuel injection valve 3. Controls fuel injection amount.

Next, the flowchart shown in FIG. 3 will be explained.

At Sl, the basic injection amount TP (= K
x Q/N). This i-function corresponds to the basic injection amount setting means.

At S2, water temperature sensor 8. The start switch 11° adjusts the water temperature increase correction coefficient based on the signal from the idle contact of the throttle sensor 6; 8. Starting and post-starting increase correction coefficient K A
S r Set ^1 to the post-idle increase correction coefficient.

In S3, □1 is searched for the lowland mixture ratio correction coefficient from the three-dimensional map stored in the memory based on the basic injection amount T calculated in Sl and the engine rotational speed N. The map stored in the memory and its search function constitute lowland mixing ratio correction coefficient setting means.

In S4, the high-altitude mixture ratio correction coefficient is set by □1 from the three-dimensional map stored in the memory based on the throttle valve opening θ according to the signal from the throttle sensor 6 and the engine rotational speed N.
Search for 1. In this case, the map and its search function constitute high altitude mixing ratio correction coefficient setting means.

Here, regarding K MIIL and K MIN, KMIIL >01 Ks in a predetermined high output region, respectively.
*n > O, and the higher the load within this operating range, the larger the value of KMIIL, K□11 becomes. In other operating ranges, KMIIL = 0,
KMI□=O, and no mixing ratio correction is performed.

In lowlands, as shown in Figure 4, □1〉
The operating range in which it is 0 is wider than the operating range in which it is >0, and for the same operating conditions within this operating range, KM, IL>K□, but at high altitudes, Due to the decrease in air density, TP for θ is lower than in lowlands, so as shown in Figure 5, the operating region where □, l>0 becomes wider than the operating region where KMIIL > 0, and K for the same operating conditions within the operating range
It is set so that MRII>K14RL.

In S5, S3. S4. Compare □ and □9 found in Select as KHm.

Further, in the case of □ and <KMRH in the comparison in S5, the process proceeds to S7 and selects the same K MIH (□ as the mixture ratio correction coefficient).

That is, 55. S6. The function of S7 constitutes a mixture ratio correction coefficient selection means.

In S8, the various increase correction coefficients obtained in S2 and S6 or S7 are added to obtain a total correction coefficient C0EF.

In S9, it is determined whether the operating range is where air-fuel ratio feedback control (λ control) is performed. This occurs when the water temperature is below a predetermined temperature, when the fuel is cut, when the air-fuel ratio continues in a rich or lean state for a predetermined period of time, during cranking and early startup, and when the KMR determined in S6 or S7 is high.

It is determined that the air-fuel ratio feedback control should be stopped when the value becomes a positive value used during high load, and in this case, the process proceeds to SIO and is fixed at the air-fuel ratio feedback correction coefficient α-1.

In operating ranges other than the above, it is determined that air-fuel ratio feedback control should be performed, and the process proceeds to 511.

At step 311, the output from the OX sensor 10 and the slice level are compared, and the air-fuel ratio feedback correction coefficient α is set by proportional-integral control.

At 512, a voltage correction numerator is set based on the battery voltage from battery 12.

At 513, the injection amount T is calculated according to the following equation.

T I = T P X COE F X α + T.

In S14, a drive pulse signal corresponding to the injection amount T1 is output to the drive circuit 14 at a timing synchronized with engine rotation.

Here, the functions 88 to S14 constitute a fuel injection amount correction means.

In this way, in lowlands, the mixture ratio correction coefficient KMII is set using T, which is obtained based on the mass intake flow rate from the hot-wire flowmeter 5 as the engine load condition, as in the past, so highly accurate air-fuel ratio control is possible. can be done.

On the other hand, at high altitudes, the mixture ratio correction coefficient KNII is set using the throttle valve opening θ as the engine load condition for the reason mentioned above. Fuel increase correction can be performed and good drivability can be obtained.

Furthermore, since the mixture ratio correction coefficient KMR for lowlands and highlands can be automatically switched only by software without using an air density sensor (intake pressure sensor) or the like, it is extremely advantageous in terms of cost.

Furthermore, when going from a lowland to a highland, the area where KMIIL>0 and the area where KMRll>0 gradually approach and switch smoothly, so there is no discomfort and the driving feeling is excellent.

<Effects of the Invention> As explained above, according to the present invention, it is possible to achieve an operation range in which fuel increase correction is performed with priority given to output even at high altitudes where air density decreases while ensuring highly accurate air-fuel ratio control at low altitudes. This ensures good drivability even when overtaking or pitching, and the switching can be done automatically using only software, which is advantageous in terms of cost. It has various advantages such as excellent driving feeling.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration 1 function of the present invention, FIG. 2 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 3 is a flowchart showing the control process of the above embodiment, and FIG. FIG. 5 is a diagram showing the setting state of the mixture ratio correction coefficient in the lowland area of the same embodiment as above, and FIG. 5 is a diagram showing the setting state of the mixture ratio correction coefficient in the highland area of the same embodiment. 1... Internal combustion engine 2... Intake passage 3... Fuel injection valve 4... Throttle valve 5... Hot wire flow meter 6... Throttle sensor 7... Crank angle sensor 13... Control unit 14...
・Driving patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima Figure 2 Figure 3 Part 1 Figure 3 Part 2

Claims (1)

[Claims] A hot-wire type that controls the current value to the hot-wire resistor in order to keep the resistance value of the hot-wire resistor installed in the engine's intake passage constant against changes in intake flow rate, and detects the intake flow rate corresponding to this current value. Fuel is injected from a fuel injection valve provided in an intake passage based on the intake flow rate detected by the hot-wire flowmeter and the engine rotation speed detected by the engine rotation speed detection means. and means for increasing the fuel injection amount by multiplying the basic injection amount by a mixture ratio correction coefficient in a predetermined high-output operation region conditioned on engine load and engine rotation speed. In an electronically controlled fuel injection system for an internal combustion engine, an operating range in which fuel increase correction is performed at low altitudes and a mixture ratio correction coefficient value in the operating range are set based on the basic injection amount and engine rotational speed as engine load conditions. means for setting a mixture ratio correction coefficient for low altitudes; means for detecting the opening degree of a throttle valve installed in the intake passage; and means for increasing the amount of fuel at high altitudes based on the throttle valve opening degree and engine speed as engine load conditions. The mixture retrieved from the high-altitude mixture ratio correction coefficient setting means for setting the operation region to be corrected and the mixture ratio correction coefficient value in the operation region, the low-altitude mixture ratio correction coefficient setting means, and the high-altitude mixture ratio correction coefficient setting means, respectively. 1. An electronically controlled fuel injection system for an internal combustion engine, comprising means for comparing ratio correction coefficients and selecting a larger mixture ratio correction coefficient.