JP3781882B2 - Engine fuel control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine fuel control device, and more particularly to a fuel control device at the time of engine acceleration.
[0002]
[Prior art]
Conventionally, a fuel increase control method for correcting an air-fuel ratio at the time of acceleration of an engine equipped with an electronic fuel injection control device has been proposed in, for example, Japanese Patent Publication Nos. 54-27491 and 62-31177.
[0003]
In recent control apparatuses, atmospheric pressure is detected by an atmospheric pressure sensor, and the air-fuel ratio is corrected using the detected data. FIG. 6 shows a fuel increase control method during engine acceleration using atmospheric pressure data.
[0004]
In the case of the synchronous acceleration increase injection method in which the fuel increase amount at the time of acceleration is added to the normal injection pulse that starts injection from the reference crank position of the engine for injection, as shown in the equation A in FIG. By _{multiplying the} time (T ₀ ) by the acceleration increase basic pulse time (T _ACC0 ) and the correction factors (K _A , K _W , K _P ) for the intake air temperature, cooling water temperature, and atmospheric pressure, The pulse time (Ti) is calculated.
[0005]
On the other hand, regardless of the crank position of the engine, when the asynchronous injection method simultaneously accelerating fuel increment injection and it is determined that the acceleration, normal normal injection basic pulse time (T ₀₎ to the above correction coefficient (K _A, By multiplying (K _W , K _P ), the pulse time after normal correction (Tu) is calculated (see equation B-1 in FIG. 6), and at the time of acceleration increase, the acceleration increase basic pulse time (T _ACC0 ) is _calculated . By multiplying each of the correction coefficients (K _A , K _W , K _P ), a pulse time after correction for acceleration increase (T _ACC ) is calculated (see equation B-2 in FIG. 6). Note that the sum of the asynchronous post-correction pulse time and the acceleration boost basic pulse time is the same as the total pulse time of the synchronous acceleration boost injection method (Tu + T _ACC = Ti).
[0006]
[Problems to be solved by the invention]
However, in the method for correcting the air-fuel ratio based on the atmospheric pressure using the above-described formula A or formulas B-1 and B-2, good atmospheric pressure correction is not performed during engine acceleration for the reasons described below.
[0007]
The reason for this is that, for example, during an acceleration operation that opens the throttle from the closed position to the open position, intake air in an amount proportional to the throttle opening (α) is immediately supplied into the cylinder, but at the same time, the intake passage The fuel injected into the cylinder reaches the cylinder after the intake air.
[0008]
Of the fuel injected into the intake passage, the amount that reaches the cylinder in the form of a mist and reaches the cylinder is the fuel injection state, engine temperature, intake air amount and temperature, air pressure, and fuel injection port Although it depends on various conditions such as the distance from the cylinder to the cylinder and the shape of the intake passage, it is approximately one-half to one-half. The remaining fuel adheres to the intake passage and the inner wall surface of the engine to become a wall-attached fuel, and the amount of fuel actually supplied into the cylinder is added to the fuel directly injected with the wall-attached fuel. .
[0009]
At the time of acceleration, the flow rate of the intake air is increased and the wall-attached fuel is sent into the cylinder. In addition, as described above, only a part of the fuel that has been determined to be in an accelerated state and injected in an increased amount is directly fed into the cylinder, but one to several combustions immediately after acceleration are generated from the existing wall-attached fuel. It will be covered by assistance.
[0010]
The phenomenon described above is particularly noticeable in the case of a crank chamber pressurized two-cycle engine in which the distance from the injection port provided in the intake passage to the cylinder is long and the wall surface area is large.
[0011]
Originally, it is desirable to set the amount of fuel supplied to the engine to be thin in consideration of purification of exhaust gas and improvement of fuel consumption rate (fuel consumption). Therefore, the amount of fuel attached to the wall surface is also set so that fuel efficiency is improved during normal operation. In high altitudes where the atmospheric pressure is low, the fuel injection amount is corrected to decrease by atmospheric pressure correction in accordance with the decrease in air density.
[0012]
In this case, the amount of fuel adhering to the wall surface at high altitude is naturally less than that at low altitude, and it is difficult to make up for the shortage with only the fuel injected in an increased amount when the engine is accelerated. Furthermore, since the combustion pressure also decreases at high altitudes where the air density is low, the deterioration of driving feeling accompanying leaning at the time of acceleration appears more conspicuously than under similar conditions in low altitudes.
[0013]
Therefore, in the high altitude where the atmospheric pressure is low, it is necessary to make the ratio of the atmospheric pressure correction amount corresponding to the acceleration increase amount larger than the correction amount of the normal injection amount, which is shown by equations A, B-1 and B-2 in FIG. In the conventional control method, both the normal amount and the increase amount are corrected by one atmospheric pressure correction coefficient (K _P ). _{Therefore, if the} acceleration increase basic pulse time (T _ACC0 ) appropriate in the lowland is set, the high altitude While the air-fuel ratio becomes lean during acceleration and the driving feeling deteriorates, if the acceleration increase basic pulse time (T _ACC0 ) appropriate for high altitude is set, the air-fuel ratio becomes rich during acceleration in low altitude, and the exhaust gas state and Fuel consumption deteriorates.
[0014]
Furthermore, in an engine equipped with a Karman vortex type or hot wire type air flow meter and a system for directly measuring the intake air flow rate, the change in intake air amount due to the acceleration operation of the engine can be determined instantaneously, but the throttle opening ( In an engine equipped with an α-N system that estimates the intake air amount from α) and the engine speed (N), the throttle operation changes to a predetermined value in order to determine the acceleration operation after determining the amount of change in the throttle opening. The fuel increase operation is delayed until the amount is indicated.
[0015]
For this reason, the engine is burned by the normal amount of injected fuel and wall-attached fuel until acceleration is determined and fuel is increased, so the fuel during acceleration operation tends to be in a lean state, especially air. In high altitude areas where the density is low, there is a risk of significant deterioration in driving feeling for the reasons described above.
[0016]
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an engine fuel control device that improves the fuel consumption rate, the exhaust gas state, and the operation feeling regardless of the atmospheric pressure. .
[0017]
[Means for Solving the Problems]
In order to solve the above-described problem, an engine fuel control apparatus according to the present invention is an engine fuel control system that electronically increases the fuel injection amount during acceleration based on atmospheric pressure information . In the fuel control device, in addition to the general atmospheric pressure correction coefficient used during normal operation, the general atmospheric pressure is adjusted so that the increase correction is performed in a region where the atmospheric pressure is low than when the general atmospheric pressure correction coefficient is used. Set a dedicated atmospheric pressure correction coefficient for the acceleration increase that changes more slowly than the change amount of the correction coefficient with respect to the atmospheric pressure, and increase the fuel injection amount using the dedicated atmospheric pressure correction coefficient for the acceleration increase during the acceleration operation of the engine It is comprised so that it may do.
[0018]
In order to solve the above-described problem, as described in claim 2, the engine is a crank chamber pressurized two-cycle engine.
[0019]
Further, in order to solve the above-mentioned problem, as described in claim 3, an α-N control system for estimating the intake air amount based on the engine rotation signal and the throttle valve opening signal is provided. It is.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a system schematic diagram of a general electronic fuel injection control apparatus (EFI) used in a two-cycle engine.
[0022]
The two-cycle engine 1 is a general crank chamber pressurization type water-cooled two-cylinder two-cycle engine, and a crankshaft 3 is rotatably supported in the two-cycle engine 1. A cylinder 5 is formed in the cylinder block 4, and a piston 6 is inserted into the cylinder block 4 so as to be slidable in a direction perpendicular to the crankshaft 3. The piston 6 and the crankshaft 3 are connected by a connecting rod 7 so that the reciprocating stroke of the piston 6 is converted into the rotational motion of the crankshaft 3.
[0023]
A magnet device 8 is provided at one end of the crankshaft 3, and a cylinder is discriminated near the periphery of the flywheel magneto 9, for example, and the rotation angle of the crankshaft 3 and its rotation speed, that is, the rotation speed (N) of the engine 1 is determined. An electromagnetic pickup coil 10 to be detected is installed. An exciter 11 is arranged inside the flywheel magneto 9.
[0024]
Further, the magnet device 8 outputs AC power and also supplies power to various devices such as a control unit 12, a fuel injector 13, and a fuel pump 14 described later.
[0025]
On the other hand, for example, the cylinder block 4 is provided with a coolant temperature sensor 15 that detects the coolant temperature of the engine 1. A combustion chamber 17 is formed at the joint between the cylinder head 16 and the cylinder block 4, and a spark plug 18 is attached to the center of the combustion chamber 17 from the outside.
[0026]
An intake passage 20 having a throttle valve 19 is connected to the crank chamber 2. A throttle opening sensor 21 that detects the opening (α) of the throttle valve 19 is provided, for example, outside the intake passage 20. Further, a fuel injector 13 is attached to the intake passage 20 downstream from the throttle valve 19 from the outside. Then, the fuel in the fuel tank 22 is pumped up by the fuel pump 14 and guided to the fuel injector 13 through the delivery pipe 23. The fuel pressure in the delivery pipe 23 is adjusted by the pressure regulator 24 so that the fuel pressure applied to the fuel injector 13 is always constant.
[0027]
Fuel injection by the fuel injector 13 is electronically controlled by the EFI 25 described above. The EFI 25 includes an electronic fuel control unit 12 (hereinafter abbreviated as ECU). The ECU 12 estimates the intake air amount based on, for example, the engine rotation signal (N) sent from the electromagnetic pickup coil 10 and the opening signal (α) of the throttle valve 19 sent from the throttle opening sensor 21. The cooling water temperature data from the cooling water temperature sensor 15 provided on the wall of the cylinder block 4, the intake air temperature data from the air temperature sensor 26 provided in the intake passage 20, and the outside of the engine 1 The fuel injection time is controlled using the atmospheric pressure data from the atmospheric pressure sensor 27 arranged at the position so as to obtain an optimum air-fuel ratio.
[0028]
Furthermore, the ECU 12 controls the timing of injecting fuel for each cylinder 5 based on the rotation angle signal of the crankshaft 3 sent from the electromagnetic pickup coil 10. That is, the fuel injector 13 of each cylinder 5 is controlled to inject fuel for a predetermined time at a time determined according to a signal from the ECU 12.
[0029]
In addition to controlling the fuel injection time and timing, the ECU 12 also sends an ignition signal to the ignition coil 28 that operates the spark plug 18 and controls the operation of the fuel pump 14.
[0030]
Next, FIG. 2 illustrates an embodiment of a fuel increase control method during engine acceleration using atmospheric pressure data.
[0031]
In the case of the synchronous acceleration increase injection method in which the fuel increase amount at the time of acceleration is added to the normal injection pulse that starts injection from the reference crank position of the engine 1 and the injection is performed, as shown in Equation 1 of FIG. Multiply pulse time (T ₀ ) by general atmospheric pressure correction coefficient (K _P ) and multiply acceleration basic pulse time (T _ACC0 ) by acceleration increase dedicated atmospheric pressure correction coefficient (K _PACC ) The total pulse time (Ti) is calculated by multiplying the sum of the above and the correction coefficients (K _A , K _W ) of the intake air temperature and the cooling water temperature.
[0032]
On the other hand, regardless of the crank position of the engine 1, the case of asynchronous injection method simultaneously accelerating fuel increment injection and it is determined that the acceleration, normal normal injection basic pulse time (T ₀₎ to the above correction coefficient (K _A , K _W , K _P ) to calculate the normal corrected pulse time (Tu) (see Equation 2-1 in FIG. 2), and during acceleration increase, the acceleration increase basic pulse time (T _ACC0 ) _Is multiplied by the correction factor (K _A , K _W ) for the intake air temperature and the cooling water temperature and the atmospheric pressure correction factor (K _PACC ) for acceleration increase, and the pulse time after correction for acceleration increase (T _ACC ) is calculated (See Equation 2-2 in FIG. 2). Note that the sum of the asynchronous post-correction pulse time and the acceleration boost basic pulse time is the same as the total pulse time of the synchronous acceleration boost injection method (Tu + T _ACC = Ti).
[0033]
Next, a second embodiment of the fuel increase control method during engine acceleration using atmospheric pressure data will be described with reference to FIG.
[0034]
In the case of the synchronous acceleration increase injection method in which the fuel increase amount at the time of acceleration is added to the normal injection pulse that starts the injection from the reference crank position of the engine 1 and the injection is performed, as shown in Equation 3 in FIG. The intake air temperature and cooling water temperature combined with the product of the pulse time (T ₀ ) multiplied by the general atmospheric pressure correction factor (K _P ) and the atmospheric pressure correction acceleration increase basic pulse time (T _ACC1 ) The total pulse time (Ti) is calculated by multiplying the correction coefficients (K _A , K _W ).
[0035]
On the other hand, regardless of the crank position of the engine 1, the case of asynchronous injection method simultaneously accelerating fuel increment injection and it is determined that the acceleration, normal normal injection basic pulse time (T ₀₎ to the above correction coefficient (K _A , K _W , K _P ) to calculate the normal corrected pulse time (Tu) (see Equation 4-1 in FIG. 3), and at the time of acceleration increase, the atmospheric pressure correction acceleration increase basic pulse time ( By multiplying T _ACC1 ) by the correction coefficients (K _A , K _W ) of the intake air temperature and the cooling water temperature, the pulse time after correction for acceleration increase (T _ACC ) is calculated (formula 4-2 in FIG. 3). reference). Incidentally, the atmospheric pressure correction acceleration increase basic pulse time _{(T ACC1)} is obtained by multiplying the acceleration increase basic pulse time _{(T ACC0)} and the acceleration increment only atmospheric pressure correction coefficient _{(K PACC) (T ACC0 ×} K _PACC = _{T ACC1).} Further, when the asynchronous normal pulse time after correction and the acceleration boost basic pulse time are added, the total pulse time of the synchronous acceleration boost injection method is the same (Tu + T _ACC = Ti).
[0036]
4 (a) and 4 (b) are graphs showing the relationship between the acceleration increase basic pulse time (T _ACC0 ) and the engine speed (N), a general atmospheric pressure correction coefficient (K _P ), and acceleration increase. The graph which shows the relationship between a minute exclusive atmospheric pressure correction coefficient ( _KPACC ) and atmospheric pressure (P) is shown. Also shows a three-dimensional map for determining from the atmospheric pressure correction acceleration increase basic pulse time in FIG. 5 and (T A _{CC0 1)} the engine speed (N) and the atmospheric pressure (P).
[0037]
As described above, an acceleration increase dedicated atmospheric pressure correction coefficient (K _PACC ) is set separately from the general atmospheric pressure correction coefficient (K _P ) used during normal operation, and this dedicated atmospheric pressure correction is performed during engine 1 acceleration operation. By using the coefficient (K _PACC ) to increase the fuel injection amount, the fuel consumption rate, exhaust gas condition and operating feeling deteriorated due to changes in air density caused by factors such as conventional altitude differences. Is prevented.
[0038]
【The invention's effect】
As described above, according to the engine fuel control apparatus of the present invention, the engine fuel control apparatus that electronically increases the fuel injection amount during acceleration based on atmospheric pressure information is used during normal operation. Aside from the general atmospheric pressure correction coefficient, the general atmospheric pressure correction coefficient is slower than the amount of change with respect to the atmospheric pressure so that the increase correction is performed in the low atmospheric pressure region than when the general atmospheric pressure correction coefficient is used. to set the acceleration increment only atmospheric pressure correction coefficient which varies, because that is configured to increase control of the fuel injection quantity by using the acceleration increment only atmospheric pressure correction coefficient at the time of acceleration operation of the engine, regardless of the atmospheric pressure Therefore, the fuel consumption rate, the exhaust gas state and the driving feeling are improved.
[0039]
Further, since the engine is a crank chamber pressurization type two-cycle engine, the above effect is further enhanced.
[0040]
Further, since the α-N control method for estimating the intake air amount based on the engine rotation signal and the throttle valve opening signal is provided, the above effect is further enhanced.
[Brief description of the drawings]
FIG. 1 is a system schematic diagram of a general electronic fuel injection control device used in a two-cycle engine.
FIG. 2 is a formula showing a first embodiment of a fuel increase control method during engine acceleration of the engine fuel control apparatus according to the present invention.
FIG. 3 is a formula showing a second embodiment of the fuel increase control method during engine acceleration of the engine fuel control apparatus according to the present invention.
FIGS. 4A and 4B are a graph showing the relationship between the acceleration increase basic pulse time and the engine speed, a general atmospheric pressure correction coefficient, an acceleration increase dedicated atmospheric pressure correction coefficient, and atmospheric pressure, respectively. The graph which shows the relationship.
FIG. 5 is a three-dimensional map for obtaining an atmospheric pressure correction acceleration increase basic pulse time from an engine speed and atmospheric pressure.
FIG. 6 is a formula showing a method for controlling fuel increase during acceleration of an engine using conventional atmospheric pressure data.
[Explanation of symbols]
1 2-cycle engine 12 Electronic fuel control unit (ECU)
15 Cooling water temperature sensor 21 Throttle opening sensor 25 Electronic fuel injection control device (EFI)
26 Air temperature sensor 27 Atmospheric pressure sensor K _{A Intake} air temperature correction coefficient K _P General-purpose atmospheric pressure correction coefficient K _PACC acceleration increment dedicated atmospheric pressure correction coefficient K _W Cooling water temperature correction coefficient T ₀ Normal injection basic pulse time T _ACC acceleration increment correction after the pulse time _{T ACC0} acceleration increase basic pulse time _{T ACC1} atmospheric pressure correction acceleration increase basic pulse time Ti total pulse time Tu normal amount corrected pulse time

Claims (3)

In an engine fuel control device that electronically increases the amount of fuel injected during acceleration based on atmospheric pressure information, the above-mentioned general-purpose large pressure is applied in a low-pressure region separately from the general atmospheric pressure correction coefficient used during normal operation. Set a dedicated atmospheric pressure correction coefficient for acceleration increase that changes more slowly than the amount of change in the general atmospheric pressure correction coefficient relative to the atmospheric pressure so that the increase correction is greater than when using the atmospheric pressure correction coefficient. A fuel control apparatus for an engine, characterized in that the fuel injection amount is controlled to be increased using the atmospheric pressure correction coefficient dedicated to the acceleration increase amount during operation. The engine fuel control device according to claim 1, wherein the engine 1 is a crank chamber pressurized two-cycle engine. The engine fuel control device according to claim 1 or 2, further comprising an α-N control method for estimating an intake air amount based on an engine rotation signal (α) and an opening signal (N) of the throttle valve 19.

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