JPH0219626A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To make it possible to constantly obtain optimum fuel increase regardless of operating conditions where an engine runs by changing an exhaut-system protective fuel increasing range, depending on atmospheric pressure. CONSTITUTION:In a control circuit 10, a pressure sensor 3 detects atmospheric pressure and intake-pipe pressure, and the detected intake-pipe pressure is corrected by the atmospheric pressure. When a range in which fuel increasing is required is decided based on the corrected intake-pipe pressure, and the range is decided to be the fuel increasing range, the fuel injection quantity is increased. Even if the atmospheric pressure fluctuates, the fuel increasing range is thus properly determined, depending on the intake-pipe pressure.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fuel injection control device for an internal combustion engine, and more particularly to a fuel injection control device for an internal combustion engine that increases the amount of fuel in response to the intake pipe pressure of the engine. .

[Conventional technology]

Conventionally, the fuel injection amount is determined from the intake air pressure (intake pipe pressure) in the intake pipe of an internal combustion engine and the engine speed.
- In the J system, in order to protect the catalyst and exhaust system parts installed in the exhaust gas passage of the engine from high-temperature exhaust gas, when increasing the amount of fuel when the engine is accelerating or under high load, first,
Based on the intake pipe pressure PM and the engine speed NB, it is determined whether or not the fuel amount is in an increase region, and the fuel amount is increased only when the fuel amount is in the increase region (see Japanese Patent Laid-Open No. 59-203834).

[Problem to be solved by the invention]

However, conventional fuel injection control devices for internal combustion engines are
Even in a flat area where no increase in fuel is required, if the atmospheric pressure decreases and the volumetric efficiency of intake air increases, the exhaust temperature will rise, making it difficult to increase the amount of fuel even though it is necessary. If this is not done, there is a risk that the catalyst may deteriorate or the lifespan of exhaust system parts may be shortened, resulting in deterioration of vehicle reliability and problems such as deterioration of emissions due to changes in exhaust system parts over time. On the other hand, when the atmospheric pressure rises, the amount may be increased in a region where it is unnecessary, and in this case there is a problem that fuel efficiency deteriorates.

An object of the present invention is to solve the problems of the conventional fuel injection control device for an internal combustion engine that increases the amount of fuel, and to provide a fuel injection system for an internal combustion engine that always increases the optimal amount of fuel no matter what operating state the engine is in. The purpose is to provide a control device.

[Means to solve the problem]

The configuration of a fuel injection control device for an internal combustion engine according to the present invention that achieves the above object is shown in FIG.

The fuel injection control device for an internal combustion engine according to the present invention includes an atmospheric pressure detection means for detecting atmospheric pressure, an intake pipe pressure detection means for detecting the intake pipe pressure of the internal combustion engine, and an intake pipe pressure correction means. corrects the intake pipe pressure by atmospheric pressure. The increase area determination means determines an area in which an increase in fuel is required based on at least the corrected intake pipe pressure, and the fuel increase means performs fuel injection when the increase area is determined to be an increase area by the increase area determination means. Increase the amount.

[For production]

In the fuel injection control device for an internal combustion engine of the present invention, atmospheric pressure and intake pipe pressure are first detected, and the detected intake pipe pressure is corrected by the atmospheric pressure. Then, a region where an increase in the amount of fuel is required is determined based on the corrected intake pipe pressure, and when it is determined that the amount of fuel is in the increase region, the fuel injection amount is increased.

Therefore, even if the atmospheric pressure changes, the increase range according to the intake pipe pressure will be appropriate.

〔Example〕

Embodiments of the present invention will be described in detail below using the drawings.

FIG. 2 schematically shows an electronically controlled fuel injection type internal combustion engine 1 equipped with an embodiment of the fuel injection control device for an internal combustion engine according to the present invention.

In this figure, reference numeral 12 is a throttle valve that adjusts the amount of intake air taken into the combustion chamber of the engine in conjunction with an accelerator pedal (not shown). This throttle valve 12 is closed during idling operation, and its opening degree increases as the engine load increases. The throttle valve 12 has a built-in potentiometer 13, which outputs a voltage proportional to the opening degree of the throttle valve 12.
An idle switch 14 is provided for detecting full closure. The potentiometer 13 is connected to A/
The idle switch 14 is connected to the D converter 101 , and the idle switch 14 is connected to the human output (Ilo) interface 102 .

In addition, a pressure sensor 3 is provided in a surge tank 21 provided downstream of the throttle valve 12 to detect the intake pressure in the intake pipe.
is provided. For example, a semiconductor sensor using a silicon thin film that generates a potential difference due to strain proportional to pressure is used as the pressure sensor 3, and a pressure signal is extracted as a potential difference proportional to absolute pressure. This pressure signal is supplied to an A/D converter 101 with a built-in multiplexer of a control circuit 10, which will be described later.

A fuel injection valve 7 is provided for each cylinder, and when energized, the valve opens and supplies pressurized fuel from a fuel supply system (not shown) to the intake port.

Crank angle sensors 5 and 6 are connected to the distributor 4, and the crank angle sensor 6 outputs one reference position detection pulse every 30 degrees of crank angle (30 degrees CA), and detects the crank angle. Sensor 5 is detected every time the IJ computer shaft makes one revolution, that is, every two revolutions of the engine (7
every 20°C'A) at the reference position (e.g. top dead center of a specific cylinder)
It outputs one pulse to determine the cylinder of the engine.

Pulse signals from these crank angle sensors 5 and 6 are supplied to an input/output interface 102 of a control circuit 10, and the output of the crank angle sensor 6 is supplied to an interrupt terminal of a CPU 103.

In addition, in the cooling water passage W of the cylinder block of engine 1,
A water temperature sensor 11 is provided that detects the temperature of the cooling water and generates an analog voltage proportional to the engine water temperature THW.

The signal from this water temperature sensor 11 is also sent to the A/D of the control circuit 10.
It is supplied to converter 101.

Furthermore, the exhaust passage 8 generates an electric signal according to the concentration of oxygen components in the exhaust gas. A sensor 9 is provided.

The output of this zero sensor 9 is supplied to the input/output interface 102 via a buffer circuit 109 and a comparison circuit 110 of the control circuit 10.

The control circuit IO is configured using, for example, a micro combinator, and includes the aforementioned A/D converter 101, input/output interface 102, CPU 103, buffer circuit 109,
In addition to the comparison circuit 110, ROM 104 and RAM 105
, a backup RA Mill, a bus 112 connecting these, etc. are provided.In addition, in the control circuit 10, a down counter 106, a flip-flop 10
7 and a drive circuit 108 are for controlling the fuel injection valve 7. That is, when the fuel injection amount TAU is calculated, the fuel injection amount TA[I is preset in the down counter 106 and the flip-flop 107 is also set. As a result, the drive circuit 108
starts energizing. On the other hand, when the down counter 106 counts the clock signal (not shown) and the carrier voltage terminal reaches the '1'' level, the flip-flop 107 is reset and the drive circuit 108 controls the fuel injection valve 7. In other words, the above-mentioned fuel injection amount TAU
The fuel injector 7 is energized and therefore the fuel injection ITA
An amount of fuel corresponding to U is sent into the combustion chamber of the engine body 1. Note that the interrupt generation of the CPU 103 is caused by the A/D
These include when the converter 101 completes A/D conversion, when the input/output interface 102 receives a pulse signal from the crank angle sensor 6, and so on.

In addition to this, the control circuit 10 includes a vehicle speed sensor 17 provided on a speedometer cable from the transmission 16.
Detection signals are sent from etc. In addition, the control circuit 10
An ignition signal is outputted to the igniter built in the distributor 4, thereby controlling the energization of the spark plug 15, but since these are not directly related to the present invention, their explanation will be omitted.

The detection signal of the intake air amount data of the pressure sensor 3 and the cooling water temperature data THW are converted into binary signals by an A/D conversion routine executed at predetermined time intervals, and are stored in the RAM each time.
The data is updated and stored in a predetermined area of 105.

Next, the control circuit 1 in the engine 1 configured as described above
The operation of 0 will be explained using the flowcharts of FIGS. 3 and 5.

FIG. 3 shows an atmospheric pressure detection routine, which is executed at a predetermined A/D conversion period, for example, every 4 ms. Step 301
Then, the engine speed Nu and the opening degree TA of the throttle valve 12 are read from the RAM 105. Then, in step 302, the air intake throttle valve opening α at the engine speed NB is
is calculated using a map as shown in FIG. 4 stored in ROM2O3.

This air intake throttle opening degree α will be explained. Second
In the illustrated embodiment, since the engine is not provided with an atmospheric pressure sensor, the atmospheric pressure is taken in using the detected value of the pressure sensor 3 provided downstream of the throttle valve 12 in the intake passage 2. However, when the opening degree of the throttle valve 12 is small, the downstream side of the throttle valve 12 becomes negative pressure and does not indicate atmospheric pressure, so in the embodiment shown in FIG. 2, the opening degree of the throttle valve 12 exceeds a certain value, Atmospheric pressure cannot be detected until the difference with atmospheric pressure becomes smaller. The opening degree of the throttle valve 12 at which the difference between the detected value of the pressure sensor 3 and the atmospheric pressure becomes minute is α here, and the value of α changes as the engine speed Nε increases, as shown in FIG. It gets bigger.

In addition, regarding the measurement of this atmospheric pressure, an atmospheric pressure sensor may be provided separately for detection.

In step 303, it is determined whether the throttle opening TA is equal to or greater than the above-mentioned atmospheric intake throttle valve opening α, and when TA≧α, that is, when the throttle valve opening TA exceeds the opening that can take in atmospheric pressure. The process proceeds to step 304, and when the value does not exceed TA, that is, when TA<α, the process proceeds to step 305.

At step 304, the time CTA after the throttle valve opening TA exceeds the opening at which atmospheric pressure can be taken in is counted, and at the subsequent step 306, it is determined whether this time CTA is greater than or equal to a predetermined value β. These two steps are performed because even if the throttle valve opening TA exceeds the opening that can take in atmospheric pressure, the pressure downstream of the throttle valve 12 does not stabilize immediately. Valve opening T
This is done after the opening degree of A is greater than or equal to the opening that allows atmospheric pressure to be taken in for a predetermined period of time. Therefore, when the result in step 303 is NO, the value of this time CTA is cleared in step 305.

If YES in step 306, that is, after a predetermined period of time has elapsed since the throttle valve opening TA exceeded the opening at which atmospheric pressure can be taken in, the process proceeds to step 307, where the latest value stored in RAM M2O3 as the atmospheric pressure value PA is The detected value PMS of the pressure sensor 3 is adopted, and RA is used as the intake pressure value PM.
The previous detected value PMO of the pressure sensor 3 stored in M2O3 is adopted and this routine is ended.

On the other hand, when the throttle valve opening TA is not at an opening that allows atmospheric pressure to be taken in (No in step 303), and when the predetermined time has not yet elapsed since the throttle valve opening T^ exceeded the opening that allows atmospheric pressure to be taken in. Step 30
6), the process proceeds to step 308.

In this step 308, RAM1 is set as the atmospheric pressure value PA.
Adopting the previous atmospheric pressure value PAO stored in 05,
The latest detection value PMS of the pressure sensor 3 stored in the RAM 105 is adopted as the intake pressure value PM, and this routine ends.

Next, the fuel injection amount calculation routine shown in FIG. 5 will be explained. In step 501, intake pipe pressure PM and engine speed N
Load B. Next, in step 502, the intake pipe pressure PM read in is corrected by atmospheric pressure. This correction is performed using the following formula.

PM=PM+ (760-PA) Xa However, for PA in this equation, the value determined in the atmospheric pressure detection routine of FIG. 3 is used, and a is a constant.

In step 503, the basic injection amount TPBSB and the volumetric efficiency correction value TPStlB are calculated using the intake pipe pressure PM corrected in step 502, but this calculation is
This is done using the map stored in M104. This map is, for example, as shown in FIGS. 6 and 7.

In step 504, it is determined whether or not the product of the engine speed Nε and the intake pipe pressure PM corrected in step 502 is greater than or equal to a predetermined value, that is, whether or not the fuel amount needs to be increased. If this is the case (NE - PM≧L), the process proceeds to step 505, where the exhaust system protection increase value FOTP is calculated using the following equation.

FOTP = NE x PM x r
+ 1 However, T is a constant. On the other hand, NB-PM<
When L, the amount is not increased, and in this case, step 50 is performed.
Proceeding to step 6, the value of the exhaust system protection increase value FOTP is set to 1.0.

Then, in the next step 507, the exhaust system protection increase value FO
1 for fuel increase values other than TP For example, a fuel increase value K such as increase due to cooling water temperature during warm-up, increase during acceleration, etc. is calculated,
Finally, in step 508, the fuel injection amount TAU is calculated using the following equation.

TAU = (TPBSB+TPStlB)
P x K x m where m is a constant.

As described above, in the fuel injection control device for an internal combustion engine according to the present invention, the exhaust system protection increase range is changed depending on the atmospheric pressure, so that an optimal exhaust system protection increase range can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, the exhaust system protection increase range is changed according to the atmospheric pressure, so changes in the volumetric efficiency of the intake air amount can be reflected in the fuel increase value, and the increase is not possible. The amount is not increased in areas where it is necessary, but it is increased appropriately in areas where it is necessary, so the temperature of the exhaust system and catalyst is maintained at an appropriate level, improving vehicle reliability and reducing emissions after aging. This has the effect of improving performance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a fuel injection control device for an internal combustion engine according to the present invention, FIG. 2 is an overall configuration diagram of an electronically controlled fuel injection internal combustion engine showing the configuration of an embodiment of the present invention, and FIG. Flowchart showing the atmospheric pressure detection procedure of the control circuit in FIG. 2, FIG. 4 showing the atmospheric pressure intake throttle opening characteristic diagram, and FIG. 5 a flowchart showing the procedure of fuel injection amount calculation in the control circuit of FIG. FIG. 6 is an intake pipe pressure car basic injection quantity characteristic diagram, and FIG. 7 is a diagram showing a volumetric efficiency map. 1... Internal combustion engine, 2... Intake passage, 3...
・Pressure sensor, 4...distribution 5, 6...
crank angle sensor, 7... fuel injection valve, 10... control circuit, 12...
... Throttle valve, 13... Potentiometer. Pyuta,

Claims (1)

[Scope of Claims] Atmospheric pressure detection means for detecting atmospheric pressure, intake pipe pressure detection means for detecting intake pipe pressure of an internal combustion engine, intake pipe pressure correction means for correcting intake pipe pressure by atmospheric pressure, and at least an increase region determination means for determining a region in which an increase in fuel is required based on the corrected intake pipe pressure; and when the increase region determination means determines that the increase region is present;
A fuel injection control device for an internal combustion engine, comprising: fuel increasing means for increasing the amount of fuel to be injected.