JPH11193737A - Fuel control of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the fuel control of the engine aiming at improvement of specific fuel consumption, state of exhaust gas, and drive feeling regardless of the atmospheric pressure. SOLUTION: This fuel control of engine, which electrically controls fuel injection amount in such a way that it increases when accelerating by using the atmospheric pressure, sets an atmospheric pressure correction coefficient only for the acceleration increase (KPACC) in addition to an atmospheric pressure correction coefficient for general (KP) to be used at the normal driving. It controls the fuel injection amount in such a way that it increases at the acceleration of the engine, using the atmospheric pressure correction coefficient only for acceleration increase (KPACC).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control system for an engine, and more particularly to a fuel control system for accelerating an engine.

[0002]

2. Description of the Related 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 is disclosed in, for example, Japanese Patent Publication Nos.
It has been proposed in JP-A-2-31177.

In recent control devices, the atmospheric pressure is detected by an atmospheric pressure sensor, and the data is used to correct the air-fuel ratio. FIG. 6 shows a fuel increase control method at the time of engine acceleration using atmospheric pressure data.

[0004] In the case of a synchronous acceleration-increased injection method in which a fuel injection amount during acceleration is added to a normal injection pulse for starting injection from a reference crank position of the engine for injection, as shown in equation A in FIG. injection basic pulse time (T ₀₎ in the acceleration increase basic pulse time (T a _CC0) the intake air temperature plus, the correction coefficient of the cooling water temperature and atmospheric pressure (K
_A , K _W , K _P ) to calculate the total pulse time (Ti).

On the other hand, regardless of the crank position of the engine, in the case of the asynchronous injection method in which acceleration is increased and fuel is injected at the same time as acceleration is determined, the above-described correction coefficients (T ₀ ) are usually added to the normal injection basic pulse time (T ₀ ). _{K a, K W, K P} ) normal amount corrected pulse time by multiplying the (Tu)
There is calculated (see Equation B-1 in FIG. 6), Furthermore, each correction coefficient at the time of acceleration increase the acceleration increase basic pulse time _{(T ACC0) (K A,} K W, K P) accelerated by crossing of The pulse time (T _ACC ) after the increase correction is calculated (see equation B-2 in FIG. 6). It should be noted that when the pulse time after the normal correction of the asynchronous type is added to the basic pulse time for the increase in acceleration, the total pulse time becomes the same as the total pulse time in the synchronous type increase injection method (T
u + T _ACC = Ti).

[0006]

However, the method for correcting the air-fuel ratio based on the atmospheric pressure using the above-described formula A or the formulas B-1 and B-2 provides a good atmospheric pressure during acceleration of the engine for the following reason. No correction is made.

The reason for this is that, for example, during an acceleration operation for opening the throttle from the closed position to the open position, an amount of intake air proportional to the opening degree (α) of the throttle is immediately supplied to the cylinder. The fuel injected into the intake passage reaches the cylinder later than the intake air.

[0008] Of the fuel injected into the intake passage, the amount of mist that gets into the air flow and reaches the cylinder depends on the fuel injection state, the engine temperature, the amount and temperature of the intake air, the air pressure, and the fuel. Although it depends on various conditions such as the distance from the injection port to the cylinder and the shape of the intake passage, it is generally about one tenth to one half. The remaining fuel adheres to the intake passage and the inner wall surface of the engine to become wall-adhered fuel, and the amount of fuel actually supplied into the cylinder is obtained by adding the wall-adhered fuel to the directly injected fuel. .

At the time of acceleration, the flow rate of the intake air increases and the fuel adhering to the wall is sent into the cylinder. Further, as described above, only a part of the fuel injected in an increased amount determined to be in the accelerated state is directly sent into the cylinder, but once to several times immediately after acceleration, the combustion from the existing wall-adhered fuel is performed. It will be covered by assistance.

The above-described phenomenon is particularly prominent in a crankcase 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 area is large.

Originally, it is desirable to set the amount of fuel supplied to the engine to be lean in consideration of purification of exhaust gas and improvement of fuel consumption rate (fuel consumption). Therefore, the amount of the fuel deposited on the wall is also set so that the fuel efficiency is improved during the normal operation. At high altitudes where the atmospheric pressure is low, the fuel injection amount is reduced by the atmospheric pressure correction in accordance with the decrease in the air density.

In this case, the amount of fuel deposited on the wall surface at high altitudes is naturally smaller than that at low altitudes, and it is likely that it is difficult to make up for the shortage with only the fuel injected in an increased amount during acceleration of the engine. Furthermore, at high altitudes where the air density is low, the combustion pressure also decreases,
Deterioration in driving feeling due to leaning during acceleration is more pronounced than in similar situations in lowlands.

Therefore, at high altitudes where the atmospheric pressure is low, it is necessary to make the ratio of the atmospheric pressure correction amount for the acceleration increase larger than the correction amount for the normal injection amount, but the equations A, B-1 and B-2 in FIG.
In the conventional control method shown in FIG. 2, one atmospheric pressure correction coefficient (K
_P ) corrects both the normal amount and the increased amount, so that the acceleration increased basic pulse time (T _ACC0 ) that is appropriate at low altitudes
Setting the air-fuel ratio becomes lean state at the time of acceleration in high altitude, while the drive feeling is deteriorated, the air-fuel ratio becomes rich state by setting the appropriate become acceleration increase the base pulse time at high altitude (T _ACC0) during acceleration in lowland,
Exhaust gas condition and fuel economy deteriorate.

Further, in an engine provided with an air flow meter of a Karman vortex type, a hot wire type or the like, and a system for directly measuring the intake air flow rate, a change in the intake air amount due to the acceleration operation of the engine can be instantaneously determined. In an engine equipped with an α-N system for estimating the intake air amount from the opening (α) and the engine speed (N), the throttle operation is determined after judging the amount of change in the throttle opening to determine the acceleration operation. The operation of increasing the fuel is delayed until a predetermined change amount is indicated.

[0015] For this reason, the normal amount of injected fuel and the fuel deposited on the wall cover the combustion of the engine until acceleration is determined and the amount of fuel is increased, so that the fuel during the acceleration operation tends to be in a lean state. In particular, at a high altitude where the air density is low, the driving feeling may be significantly deteriorated for the above-mentioned reason.

The present invention has been made in view of the above circumstances, and has as its object to provide a fuel control device for an engine in which the fuel consumption rate, the exhaust gas state, and the driving feeling are improved irrespective of the atmospheric pressure. Aim.

[0017]

According to a first aspect of the present invention, there is provided a fuel control apparatus for an engine, which uses an atmospheric pressure to accelerate a fuel injection during acceleration. In an engine fuel control system for electronically increasing the amount of fuel, a dedicated atmospheric pressure correction coefficient is set for the acceleration increase separately from the general atmospheric pressure correction coefficient used during normal operation. The fuel injection amount is controlled to increase using the correction coefficient.

According to another aspect of the present invention, the engine is a crankcase pressurized two-stroke engine.

Further, in order to solve the above-mentioned problems,
According to a third aspect of the present invention, there is provided an α-N control system for estimating an intake air amount based on an engine rotation signal and a throttle valve opening signal.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a system schematic diagram of a general electronic fuel injection control device (EFI) used in a two-stroke engine.

The two-stroke engine 1 is a common crankcase pressurized water-cooled two-cylinder two-stroke engine.
A crankshaft 3 is rotatably supported in the inside 2. A cylinder 5 is formed in the cylinder block 4, and a piston 6 is slidably inserted in the cylinder 5 in a direction perpendicular to the crankshaft 3. And piston 6
And the crankshaft 3 are connected by a connecting rod 7, and the reciprocating stroke of the piston 6 is
It is to be converted into a rotational motion.

A magnet device 8 is provided at one end of the crankshaft 3. The flywheel magnet 9 is provided with a cylinder, for example, near the periphery of the flywheel magnet 9. An electromagnetic pickup coil 10 for detecting N) is provided. An exciter 11 is arranged inside the flywheel magneto 9.

Further, the magneto device 8 outputs AC power, and also supplies power to devices such as a control unit 12, a fuel injector 13, and a fuel pump 14, which will be described later.

On the other hand, for example, the cylinder block 4 is provided with a cooling water temperature sensor 15 for detecting a cooling water temperature of the engine 1. Further, a combustion chamber 17 is formed at a 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.

An intake passage 20 having a throttle valve 19 is connected to the crank chamber 2. A throttle opening sensor 21 for detecting 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 of the throttle valve 19 from 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. Delivery pipe 2
The fuel pressure in the fuel injector 3 is controlled so that the fuel pressure applied to the fuel injector 13 is always constant.
Is adjusted by

The 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). E
The CU 12 estimates an intake air amount based on, for example, an engine rotation signal (N) sent from the electromagnetic pickup coil 10 and an opening signal (α) of the throttle valve 19 sent from the throttle opening sensor 21. N control system, and further, cooling water temperature data from a cooling water temperature sensor 15 provided on the wall of the cylinder block 4.
Injecting fuel to obtain an optimal air-fuel ratio by using data of the intake air temperature from the air temperature sensor 26 provided at 0 and data of the atmospheric pressure from the atmospheric pressure sensor 27 provided outside the engine 1. Control the time.

Further, the electromagnetic pickup coil 10
The ECU 12 controls the timing for injecting fuel for each cylinder 5 based on the rotation angle signal of the crankshaft 3 sent from the ECU. That is, the fuel injector 13 of each cylinder 5 is controlled so as to inject fuel for a predetermined time at a predetermined time according to a signal from the ECU 12.

In addition to controlling the fuel injection time and timing, the ECU 12 sends an ignition signal to an ignition coil 28 for operating the ignition plug 18 and controls the fuel pump 1
4 is also controlled.

Next, an embodiment of a fuel increase control method at the time of engine acceleration using atmospheric pressure data will be described with reference to FIG.

In the case of the synchronous accelerated increasing injection method in which the fuel injection amount during acceleration is added to the normal injection pulse for starting the injection from the reference crank position of the engine 1 for injection, as shown in equation 1 in FIG. A normal injection basic pulse time (T ₀ ) multiplied by a general atmospheric pressure correction coefficient (K _P ), and an acceleration increase basic pulse time (T _ACC0 ), an acceleration increase dedicated atmospheric pressure correction coefficient (K _PACC ). The total pulse time (Ti) is calculated by multiplying the product of the multiplication by the respective correction coefficients (K _A , K _W ) of the intake air temperature and the cooling water temperature.

On the other hand, regardless of the crank position of the engine 1, in the case of the asynchronous injection method in which acceleration is determined at the same time that acceleration is determined to be accelerated, the above-described correction coefficients are normally added to the normal injection basic pulse time (T ₀ ). (K _A , K _W , K _P ) multiplied by the pulse time after normal correction (Tu)
(See equation 2-1 in FIG. 2). When the acceleration is increased, the correction coefficients (K _A , K _W ) of the intake air temperature and the cooling water temperature and the acceleration are increased during the acceleration increase basic pulse time (T _ACC0 ). The pulse time (T _ACC ) after the acceleration increase is corrected by multiplying by the atmospheric pressure correction coefficient (K _PACC ) dedicated to the increase.
Is calculated (see Equation 2-2 in FIG. 2). It should be noted that the total pulse time of the synchronous acceleration-increase injection method is equal to the total pulse time (Tu + T _ACC = Ti) when the non-synchronized pulse time after normal correction and the acceleration-increase basic pulse time are added.

Next, a second embodiment of a fuel increase control method at the time of engine acceleration using atmospheric pressure data will be described with reference to FIG.

In the case of a synchronous acceleration-increased injection method in which the fuel is increased at the time of acceleration and added to the normal injection pulse for starting injection from the reference crank position of the engine 1 for injection, as shown in Equation 3 in FIG. The normal injection basic pulse time (T ₀ ) multiplied by a general atmospheric pressure correction coefficient (K _P ) and the atmospheric pressure correction acceleration increase basic pulse time (T _ACC1 )
The total pulse time (Ti) is calculated by multiplying the sum of these by the respective correction coefficients (K _A , K _W ) of the intake air temperature and the cooling water temperature.

On the other hand, regardless of the crank position of the engine 1, in the case of the asynchronous injection method in which the acceleration is determined and acceleration is performed at the same time as the accelerated fuel injection, the above correction coefficients are normally added to the normal injection basic pulse time (T ₀ ). (K _A , K _W , K _P ) multiplied by the pulse time after normal correction (Tu)
There is calculated (see equation 4-1 in FIG. 3), also, the correction coefficient at the time of acceleration increase the atmospheric pressure correction acceleration increase basic pulse time (T _ACC1) intake air temperature and the coolant temperature (K _A, K
By multiplying by _{W 2} ), the pulse time (T _ACC ) after the acceleration increment correction is calculated (see equation 4-2 in FIG. 3). The atmospheric pressure correction acceleration increase basic pulse time (T
_ACC1) is obtained by multiplying the acceleration increase basic pulse time _{(T AC C0)} and the accelerating increment only atmospheric pressure correction coefficient _{(K PACC) (T ACC0 ×} K PACC
= T _ACC1 ). When the pulse time after the normal correction of the asynchronous type is added to the basic pulse time for the increase in the acceleration, the total pulse time of the synchronous acceleration and the increase injection method becomes the same (Tu + T).
_ACC = Ti).

FIGS. 4A and 4B are graphs showing the relationship between the acceleration increase basic pulse time (T _ACC0 ) and the engine speed (N), and a general atmospheric pressure correction coefficient (K _P ). And the atmospheric pressure correction coefficient (K
₃ shows a graph showing the relationship between _PACC ) and the atmospheric pressure (P). 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).

As described above, a special atmospheric pressure correction coefficient (K _PACC ) is set for the acceleration increase separately from the general atmospheric pressure correction coefficient (K _P ) used during normal operation. By increasing the fuel injection amount using the atmospheric pressure correction coefficient (K _PACC ), the fuel consumption rate, the exhaust gas state, and the operation fee due to the change in air density caused by factors such as the altitude difference have been conventionally _achieved. The deterioration of the ring is prevented.

[0038]

As described above, according to the engine fuel control apparatus of the present invention, in the engine fuel control apparatus for electronically increasing the fuel injection amount during acceleration using the atmospheric pressure, A dedicated atmospheric pressure correction coefficient for increasing the acceleration is set separately from the general atmospheric pressure correction coefficient used during normal operation, and the fuel injection amount is controlled to be increased using the dedicated atmospheric pressure correction coefficient during the acceleration operation of the engine. Therefore, the fuel consumption rate, the exhaust gas state, and the driving feeling are improved regardless of the atmospheric pressure.

Further, since the engine is a crankcase pressurized two-cycle engine, the above-mentioned effect is further enhanced.

Further, α-N for estimating the intake air amount based on the engine rotation signal and the throttle valve opening signal.
Since the control method 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 for a two-cycle engine.

FIG. 2 is a formula showing a first embodiment of a fuel increase control method during engine acceleration in the engine fuel control device according to the present invention.

FIG. 3 is a formula showing a second embodiment of a fuel increase control method during engine acceleration in the engine fuel control apparatus according to the present invention.

4 (a) and 4 (b) are graphs respectively showing a relationship between an acceleration increase basic pulse time and an engine speed, and a general atmospheric pressure correction coefficient, an atmospheric pressure correction coefficient dedicated to an acceleration increase, and an atmospheric pressure. 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 the engine speed and the atmospheric pressure.

FIG. 6 is a formula showing a conventional fuel increase control method at the time of engine acceleration using atmospheric pressure data.

[Explanation of symbols]

1 Two-cycle engine 12 Electronic fuel control unit (ECU) 15 Coolant temperature sensor 21 Throttle opening sensor 25 Electronic fuel injection control device (EFI) 26 Air temperature sensor 27 Atmospheric pressure sensor K _A Correction coefficient of intake air temperature K _P General atmospheric pressure correction coefficient K _PACC acceleration increment only atmospheric pressure correction coefficient K _W coolant 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 sized use Atmospheric pressure correction acceleration increase basic pulse time Ti Total pulse time Tu Normally corrected pulse time

Claims (3)

[Claims] 1. A fuel control device for an engine that electronically controls the fuel injection amount during acceleration using the atmospheric pressure, wherein acceleration is performed separately from a general atmospheric pressure correction coefficient (K _P ) used during normal operation. Atmospheric pressure correction coefficient (K
_PACC ), and the fuel injection amount is controlled to increase using the dedicated atmospheric pressure correction coefficient (K _PACC ) during the acceleration operation of the engine 1. 2. The engine 1 is a crankcase pressurized type 2
The engine fuel control device according to claim 1, wherein the fuel control device is a cycle engine. 3. The engine according to claim 1, further comprising an α-N control system for estimating an intake air amount based on an engine rotation signal (α) and an opening signal (N) of a throttle valve 19. Fuel control device.