JPH0696996B2 - Fuel injection control device for internal combustion engine for vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine for a vehicle, which corrects the fuel injection amount during high load operation in accordance with the altitude of a vehicle running road.

<Prior Art> As a conventional device of this type, there is one previously proposed by the present applicant (Japanese Patent Application No. 58-195837).

This is ON during high load operation with throttle valve opening above a certain level.
Is provided with a throttle valve switch, and the pulse width of the injection pulse output to the electromagnetic fuel injection valve during the high load operation
Te is calculated as Te = Kf · T _P to increase and correct the fuel injection amount.

Here, Kf represents the fuel increase rate, which can be switched between high altitude operation and low altitude operation by a sensor that detects atmospheric pressure (for example, an atmospheric pressure sensor using a thin film semiconductor). In the former case, it is smaller than in the latter case. Is set.

Further, the fuel amount increase correction is performed only when a predetermined time T _D has elapsed after the throttle valve switch is turned on, that is, the high load condition is reached, and the fuel amount increase correction in the transient high load state is avoided.

FIG. 1 shows a flow chart of the operation of this product.

However, in such a fuel injection control device, the determination of the high load state in which the fuel increase is required is made in one step, and the fuel increase rate Kf and the delay time T _D are simultaneously switched between the lowland and the highland. Therefore, even under operating conditions where the throttle valve is fully opened on an uphill uphill to overtake, the fuel increase correction is performed after the delay time T _D, and an appropriate output and mixture ratio can be quickly obtained. However, the output may be insufficient, which may be dangerous in practice.

<Problems to be Solved by the Invention> The present invention has been made in view of the above-mentioned problems, and in an operating condition in which a rapid increase in output is required, the above-mentioned problems are solved by immediately performing the fuel increase correction. It is an object of the present invention to provide a fuel injection control device for an internal combustion engine for a vehicle which has been solved.

<Means for Solving Problems> Therefore, according to the present invention, as shown in FIG. 2, a means for detecting the atmospheric pressure to determine the altitude of the vehicle traveling path, and an engine state for a low level high load state. A means for separately detecting in two stages, a high level high load state close to full load, a means for measuring the duration after detecting the low level high load state, and a low level high load state Means for increasing the fuel injection amount after the delay time is set to increase with the increase in altitude with an increase rate set so as to decrease with the increase in altitude. When a high level high load state is detected, a means for correcting the fuel injection amount by an increase rate set so as to become smaller according to an increase in altitude immediately after the detection is provided.

<Operation> With such a configuration, by increasing the delay time of the fuel amount increase correction at a high load at a low level at a high altitude, the fuel increase amount at the time of a gear change or a slow acceleration due to an increase in the accelerator pedal depression amount at a high altitude is stopped or Fuel economy with small control
Exhaust properties can be prevented from deteriorating, and on the other hand, by reducing the delay time in lowlands, it is possible to avoid the fuel increase correction in a momentary low-level high-load state while ensuring the output performance required for lowland traveling. .

Further, at the time of high level and high load, it can be judged that it is a high output requirement condition such as overtaking, and regardless of the lowland or the highland, the fuel increase correction can be immediately performed to obtain the high output.

Also, in lowlands, increasing the fuel increase rate at high load makes it possible to sufficiently increase the output and enhance the acceleration performance, prevent combustion gas temperature rise, and prevent combustion chamber, piston, exhaust gas in the high load region. The durability of parts exposed to high-temperature combustion gas such as valves and exhaust manifolds can be improved, while the atmosphere is diluted in high altitudes, so the mass of air taken into the combustion chamber is small and the combustion gas temperature is low. Since it is low compared to the lowland, the fuel increase rate for lowering the combustion gas temperature is small compared to the lowland. Can be kept small.

Also, in highlands, the frequency of continuous long uphill conditions is much higher than in lowlands, and in that case, even if the delay time of fuel increase correction is long, it is not possible to cope with it, but decrease the fuel increase rate in high altitudes. Thus, it is possible to dramatically improve the fuel economy and the exhaust property when traveling on the slope.

<Example> Hereinafter, an example of the present invention is described based on a drawing.

In FIG. 3 showing the configuration of one embodiment, fuel is supplied to the engine 1 by injection from an electromagnetic fuel injector 2 mounted on an intake port portion. Reference numeral 3 is a control unit using a microcomputer, which uses an intake air flow rate Q measured by an air flow meter 4, an ignition signal from an ignition coil 5, an exhaust oxygen concentration signal detected by an O ₂ sensor 6, and a pressure sensor 7. An atmospheric pressure signal detected, a signal from the throttle switch 9 or the like which is turned on at the time of high load operation in which the opening of the throttle valve 8 is opened to a certain degree (for example, 70 °) or more is input, and the operation detected by these input signals The fuel injection amount Te is set according to the state, and an injection pulse having a pulse width corresponding to the Te is output to the fuel injector 2 to control the fuel injection amount.
Reference numeral 10 denotes a pressure regulator, which adjusts the pressure difference between the intake pipe negative pressure and the fuel pressure of the fuel injector 2 to be constant, so that the amount of fuel proportional to the valve opening time of the fuel injector 2 is supplied. It 11 is an air cleaner.

FIG. 4 shows a control block diagram of the control unit 3. The basic pulse width setting means 31 determines the basic pulse width T _P of the injection pulse based on the intake air flow rate Q and the engine speed N obtained from the ignition signal. Set as T _P = k × Q / N.

The air-fuel ratio feedback correction coefficient setting means 32 determines the air-fuel ratio λ depending on the oxygen concentration in the exhaust gas detected by the O ₂ sensor 6.
Is set to a constant value (for example, 1), an air-fuel ratio feedback correction coefficient α for controlling the fuel injection amount is set in an operating region in which the air-fuel ratio feedback control is performed. Further, the value of α is fixed in an operating region where the air-fuel ratio feedback control is not performed, such as during high load operation in which the throttle switch 9 is ON.

The high load detecting means 33 has a low level high load state in which the basic pulse width T _P is equal to or more than a set value, while the throttle switch 9 is OFF, and a full load at which the throttle switch 9 is ON or a high level close thereto. The high-load state is detected in two stages.

The atmospheric pressure correction amount setting means 34, in accordance with the atmospheric pressure detected by the pressure sensor 7, carries out the fuel amount increase correction control under the high load condition of the low level and the high level, and the fuel increase rate Kf.
And the delay time T _D for the fuel increase correction at low level and high load.

The timer 35 measures the duration of the low level high load state determined by the high load detecting means 33.

The ejection pulse width setting means 36 is the basic pulse width setting means.
31, the signal width from the air-fuel ratio feedback correction coefficient setting means 32, the high load detection means 33, the atmospheric pressure correction amount setting means 34 and the timer 35, and the pulse width of the injection pulse finally output based on these signals. Set Te. The injection pulse output means 37 outputs an injection pulse having the pulse width Te set by the injection pulse width setting means 36 to the fuel injector 2.

Next, a series of operations of this embodiment will be described based on the flowchart shown in FIG.

The intake air flow rate Q and the engine speed N are read at S1, and the basic pulse width T _P required per engine revolution is T _P = k · Q / N at S2.
(K is a proportional constant, and T _P is set to be approximately the theoretical mixing ratio).

In S3, it is determined whether or not FLAGP set in S7 or S9 is 1. If YES, the process proceeds to S4 to set the reference atmospheric pressure Po for comparison to Po = Pc + ΔP, and if NO, to S5. Go to Po
After setting = Pc, proceed to S6.

At S6, the detected atmospheric pressure P is compared with the reference atmospheric pressure Po,
Under highland driving conditions where it is determined that P <Po, S7
FLAGP is set to 1, and the fuel increase rate Kf when the low and high level high load conditions described later in S8 are detected and the fuel increase correction delay time T _D when the low level high load condition is detected are the values for high altitude Set to T _H and K _H.

Also, in lowland operation when P ≧ Po in S6, FL in S9
AGP is set to 0, and the fuel injection rate Kf and the delay time T _D are similarly set to low-level values K _L (> K _H ) and T _L (<T _H ) in S10.

Incidentally, the reason why ΔP is added in S4 when setting Kf and _TL by the above atmospheric pressure determination is to provide hysteresis as shown in FIG. 6 and prevent hunting.

After setting Kf and T _P in this way, the process proceeds to S11, and it is determined whether or not the throttle switch 9 is ON.

If the determination in S11 is NO, the process proceeds to S12, and it is determined whether or not the FLAGT set in S16 or S18 is 1, and if the determination is YES, the process proceeds to S13 and the pulse width T for comparison of the basic pulses. _F to T _F
= T _C −ΔT, and if NO, the process proceeds to S14, sets T _F = T _C, and then proceeds to S15. Here, ΔT is subtracted in S13,
This is to prevent hunting of the correction constant K setting, which will be described later, by providing hysteresis as shown in FIG.

In S15, it is determined whether the pulse width T _{P of the} basic pulse representing the load exceeds the reference pulse width T _F. In the low / medium load condition where this judgment is NO (normal air-fuel ratio feedback control is carried out), the program proceeds to S16 and FLAGT is set to 0, and then S1
The correction constant K and K = 1.0 in 7, the pulse width Te of the ejection pulse is calculated as Te = T _P · K in S23, the pulse width T in S24
The injection pulse having e is output to the fuel injector 2. In this case, the normal air-fuel ratio is controlled without performing the fuel increase correction according to the altitude condition.

If the determination in S15 is YES, the load exceeds the first level set by T _P = T _F , but the throttle valve opening is close to the full load. It was done. In this case, proceed to S18 and set FLAGT to 1, then S1
Proceed to step 9 to set the delay time T _D set in S8 or S10 after the detection of such a low level high load condition.
It is determined whether or not the above. When the judgment of S19 is NO,
That is, until the delay time T _D has elapsed, proceed to S20 and K =
After setting to 1.0, the routine proceeds to S23 and S24, and the normal air-fuel ratio control is continued without starting the fuel increase correction.

When the determination in S19 is YES, that is, when the delay time T _D elapses after the first high load state is detected, the process proceeds to S21, sets the correction constant K to K = Kf, and then proceeds to S23 and S24.

In this case, under high altitude conditions, the delay time T _D uses the value T _H set in S8, and T _H is a relatively large value of about 1.0 to 5.0 seconds. In a high load state for a long time, the fuel amount is not increased, deterioration of fuel efficiency can be suppressed, and the exhaust composition can be maintained excellent.

Also, the fuel increase rate K _H set in S8 is also used as the correction constant K, and this K _H is a relatively small value of about 1.01 to 1.20 corresponding to the small atmospheric density, so the mixture It is possible to prevent deterioration of fuel efficiency and exhaust composition from this viewpoint as well. Especially in the highlands, there is a high frequency of continuous long uphill conditions, and a steady high load condition continues.In that case, it is not possible to deal with this by increasing the delay time of the fuel increase correction, but in the highlands, By reducing the amount of increase, the fuel efficiency and exhaust properties during the uphill traveling can be dramatically improved.

On the other hand, under lowland conditions, T _D and Kf are the values set in S10.
T _L and K _L are used, T _L has a relatively small value of about 0.5 seconds or less, and Kf has a relatively large value of about 1.10 to 1.50 seconds, which improves the drivability in lowlands and improves the power performance. Can be maintained.

Next, when the determination in S11 is YES, that is, when the second high load state in which the throttle valve opening is close to full opening is detected, the process proceeds to S22, and after K = Kf, the process proceeds to S23 and S24. Immediately, the fuel increase correction is performed.

In this way, during high load operation close to full load where rapid output increase is required, the fuel amount increase correction is immediately performed and the output can be increased rapidly.

Further, the correction of the fuel amount increase at the high level and high load is also corrected at a small rate in the highland, so that the fuel consumption and the exhaust property can be prevented from deteriorating without the mixture ratio becoming too rich.

In addition, the fuel amount increase correction in the high load region is performed by lowering the combustion gas temperature in order to secure the durability of the parts exposed to the high temperature combustion gas such as the combustion chamber, the piston, the exhaust valve, and the exhaust manifold, in addition to the output increase. However, since the atmosphere is diluted in high altitudes, the mass of air taken into the combustion chamber is small and the combustion gas temperature is lower than in lowlands, so the fuel increase rate for lowering the combustion gas temperature is A small rate is required compared to lowlands, and for that reason, in the highlands, the fuel increase rate is set small so as to suppress the deterioration of fuel economy and exhaust properties.

By the way, when detecting from a low level close to medium load to a high load state close to full load as shown in Fig. 1 in one step, the density of the atmosphere is low and the engine output is insufficient at high altitudes. Therefore, the depression amount of the accelerator pedal becomes larger than that in the case of lowland. For this reason, even if the fuel increase correction is not necessary, such as when performing slow acceleration while driving in urban areas, a large amount of HC and CO will be generated if the fuel increase correction is performed by determining the high load state, In order to prevent this, the start of the correction is delayed for several seconds under all conditions for performing the fuel increase correction. However, in this case, even if a rapid output increase is required during mountainous traveling or sudden acceleration operation, the start of the increase correction is delayed for several seconds, which causes a defect such as acceleration failure. In this respect, the present invention requires a low level high load condition (a power valve operating range of a normal carburetor specification, that is, about -100 mmHg at a suction negative pressure) that does not require a rapid output increase and a rapid output increase. The above problem can be solved by detecting the high-level high-load state near the full load in two stages, and detecting the high-level high-load state without the delay time and immediately performing the fuel increase correction.

Further, since the discrimination of the level of the high load state is performed by detecting the throttle valve opening, the responsiveness of the detection at the time of acceleration is excellent as compared with the case of performing the load required related to the intake air amount, The acceleration performance can be improved as much as possible.

<Effects of the Invention> As described above, according to the present invention, the high load state is detected by distinguishing between the low level and the high level according to the throttle opening, and the low level high load state is detected. In this case, the fuel amount increase correction is started with a greater delay in higher altitudes, so that even under high altitude conditions where the accelerator pedal depression amount increases, the fuel amount increase correction is not performed during gear changes or during slow acceleration operation, or the correction time is minimized. While maintaining good fuel economy and exhaust composition as much as possible, when an output close to full throttle is required, such as when overtaking or climbing a steep slope, fuel increase correction is immediately performed to obtain good drivability. Is.

Also, by setting the fuel increase rate to a small value in highlands, the amount of increase for lowering the combustion gas temperature is reduced to maintain good durability of parts exposed to the high temperature around the combustion chamber, while improving fuel economy and exhaust gas. The deterioration of the property can be prevented, and further, the fuel increase rate can be suppressed to be low during frequent uphill traveling in a steady high load state, so that the deterioration of the fuel consumption and the exhaust property can be dramatically improved.

[Brief description of drawings]

FIG. 1 is a flow chart showing a control process of a fuel injection amount control device previously proposed by the applicant of the present application, FIG. 2 is a block diagram showing a configuration of the present invention, and FIG. 3 is an entire embodiment of the present invention. FIG. 4 is a block diagram showing the configuration, FIG. 4 is a control block diagram of the above-mentioned embodiment, FIG. 5 is a flowchart showing a control process of the above-mentioned embodiment, and FIG. 6 is a graph showing a hysteresis characteristic of altitude determination in the above-mentioned embodiment. FIG. 7 is a graph showing the hysteresis characteristic of the correction constant K in the above embodiment. 1 ... Engine, 2 ... Fuel injector, 3 ... Control unit, 4 ... Air flow meter, 5 ... Ignition coil, 7 ... Pressure sensor, 9 ... Throttle switch, 31 ... Basic pulse width setting means, 33 ... High load detection means, 34 ... Atmospheric pressure correction amount setting means, 35 ... Timer, 36 ...
... Injection pulse width setting means, 37 ... Injection pulse output means

Claims (1)

[Claims] 1. A fuel injection amount of an internal combustion engine for a vehicle, which sets a fuel injection amount on the basis of a load and a rotational speed of the engine and corrects the fuel injection amount in a high load operation in accordance with an altitude of a vehicle running road. In the control device, a means for detecting the atmospheric pressure to determine the altitude of the vehicle running path, and an engine state are detected by distinguishing between two stages of a low level high load state and a high level high load state close to full load. Means for measuring the duration after detecting the low-level high-load state, and for a delay time set so that the low-level high-load state increases in accordance with an increase in altitude, A means for increasing the fuel injection amount after the delay time has elapsed by an increase rate set so as to decrease in accordance with an increase in altitude, and a fuel injection amount immediately after the detection when a high level high load state is detected. Increase of Depending set to be smaller by a means for increasing correction by increasing rate, the fuel injection control apparatus for an internal combustion engine for a vehicle, characterized in that which is configured by providing the.