JPH03117664A - Fuel injection controller of alcohol engine - Google Patents

Abstract

PURPOSE:To secure proper combustion by selecting an injector for a single point of an intake manifold collection part under a condition where throttle opening is less than a standard value, and selecting an injector for a multiple point of every cylinder under a condition where it is more than the standard value. CONSTITUTION:In a controller 31, when opening of a throttle valve 5a detected by a sensor 9a is less than a comparison standard value of throttle opening set according to alcohol concentration of fuel detected by a sensor 14, an injector 10a for a single point provided at an intake manifold collection part 4 is selected and injected. When it is more than the standard value, a multiple point injector 10b... provided at an intake port 3 of every cylinder is selected. When it is judged to be an engine low speed range as well as a throttle full open range, a starting time of fuel injection is delayed if alcohol concentration is high, and fuel is injected. Air-fuel ratio is properly controlled, and operability and exhaust emission are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field] The present invention relates to a fuel injection control device for an alcohol engine that variably sets the fuel injection timing during low speed rotation and high load operation of the engine depending on the alcohol concentration of the fuel.

[Prior art and problems to be solved by the invention] In recent years, F F V (Nexible Fue Vehicles), which can be operated using only gasoline, only alcohol, or a mixture of gasoline and alcohol, have been developed.
) has been developed.

The alcohol concentration (content rate) in the fuel of the above alcohol engine varies between 0% (gasoline only) and 100% (alcohol only) depending on the user's circumstances when refueling, and also depends on the alcohol concentration in the fuel. Since the stoichiometric air-fuel ratio is different, it is necessary to appropriately set the air-fuel ratio and ignition timing variably according to the alcohol concentration in the fuel, as disclosed in, for example, Japanese Patent Application Laid-Open No. 56-66424.

Incidentally, since the volumetric expansion rate of alcohol when vaporized is about three times that of gasoline, the lower the volumetric efficiency due to fuel vaporization increases as the alcohol concentration in the fuel increases.

Conventionally, the fuel injection timing is generally set in the intake pipe in order to promote vaporization and stabilize combustion, and to complete at the start of intake music. If the fuel injection m is uniquely injected into the intake pipe before the intake stroke regardless of the alcohol concentration of the fuel, the higher the alcohol concentration, the lower the volumetric efficiency due to vaporization, making it impossible to properly control the air-fuel ratio. , there are problems that lead to deterioration of driving performance and deterioration of lively emissions.

Particularly, in low engine speed and high load operating regions where the amount of fuel injected is large and the injected fuel remains for a sufficient time to vaporize in the intake pipe, the volumetric efficiency decreases rapidly and the above-mentioned problems become conspicuous.

Furthermore, in the above-mentioned alcohol engine, in order to maintain the air-fuel ratio at the stoichiometric air-fuel ratio, for example,
As disclosed in the above publication, the fuel injection amount must be increased in response to an increase in the alcohol concentration in the fuel, and the injector used in a normal fuel injection system lacks capacity.

In other words, the stoichiometric air-fuel ratio when alcohol is used as fuel is approximately 1/2 of that when Ganrin is used as fuel,
Under the same operating conditions, the injector capacity should be approximately 2
Must be doubled. Therefore, a special injector must be used to ensure the required fuel injection amount.
There is a problem that this will lead to an increase in costs.

[Object of the Invention] The present invention has been made in view of the above circumstances, and it satisfies the required fuel injection amount that increases depending on the alcohol concentration, and also achieves volumetric efficiency even when the engine is running at low speed and under high load. It is an object of the present invention to provide a fuel injection control device for an alcohol engine that can appropriately control the air-fuel ratio without lowering the air-fuel ratio, improve driving performance, and improve exhaust emissions.

[Means for Solving the Problems] In order to achieve the above object, a fuel injection control device for an alcohol engine according to the present invention has a throttle opening comparison standard that sets a throttle opening comparison reference value according to the alcohol concentration of the fuel. The value setting means compares the throttle opening degree ln1 degrees from the throttle opening degree sensor with the throttle opening comparison reference value set by the throttle opening comparison reference value setting means, and determines that the throttle opening is the throttle opening comparison reference value. If the throttle opening is smaller than the throttle opening comparison reference value, the single-point injector installed at the intake manifold gathering part is selected to inject fuel, while if the throttle opening is equal to or greater than the throttle opening comparison reference value, the single-point injector installed at the intake manifold assembly is selected, and the fuel is injected at the intake port of each cylinder. an injector selection means for selecting a multi-point injector provided and injecting fuel; and when the multi-point injector is selected by the injector selection means, a fully open throttle range is set based on the throttle opening degree from the throttle g11c sensor. a fully open throttle region determining means for determining a fully open throttle region; and a low engine speed range determining means for determining a low engine speed range based on a preset reference engine speed when the multi-point injector is selected by the injector selection means; , when the throttle fully open region discriminating means determines that the throttle is fully open, and the engine low speed region discriminating means determines that the engine is in the low engine speed region, the higher the alcohol concentration t'S of the fuel, the more the multi-point This is combined with fuel injection start timing setting means for delaying and setting the start timing of fuel injection from the injector.

[Function] In the above configuration, first, a reference value for comparison between throttles is set according to the alcohol concentration of the fuel, and then the throttle opening from the throttle opening sensor is compared with the reference value for comparison of throttle opening. However, if the throttle opening is smaller than the throttle opening comparison reference value, the single point injector installed in the intake manifold assembly is selected and fuel is injected.

On the other hand, if the throttle opening is equal to or higher than the throttle opening comparison reference value, the multi-point injector installed in the intake port of each cylinder is selected, and based on the output signal of the throttle opening sensor, the throttle opening is determined to be in the fully open range. It is also determined whether the engine is in a low speed rotation range based on the engine rotation speed.

Then, when it is determined that the throttle is in the fully open region and that the engine is in the low speed rotation region, the higher the alcohol concentration of the fuel, the later the fuel injection start timing is set, and the multi-point injector is Inject fuel.

[Embodiments of the invention] Hereinafter, the present invention will be described in detail based on the drawings.

The drawings show an embodiment of the present invention, in which Fig. 1 is a functional block diagram of the control device, Fig. 2 is a schematic diagram of the control system, Fig. 3 is a front view of the crank rotor and crank angle sensor, and Fig. 4 is a front view of the crank rotor and crank angle sensor. A front view of the cam rotor and cam angle hinge, Fig. 5 is a time chart of fuel injection timing, Fig. 6 is an explanatory diagram showing the relationship between alcohol concentration and fuel injection start timing, and Fig. 7 (a) shows the alcohol S degree and FIG. 7(b) is an explanatory diagram showing the relationship between fuel injection systems. FIG. 7(b) is an explanatory diagram showing fuel injection switching when the throttle opening is constant. FIG. 8 is a correlation diagram between alcohol concentration and alcohol content correction coefficient. The figure is a flowchart showing a fuel injection control procedure.

(Configuration) Reference numeral 1 in the figure is an alcohol engine for FFV, and the figure shows a 4-cylinder horizontally opposed engine.

An intake manifold 3 is communicated with an intake port 2a formed in a cylinder head 2 of this engine 1, and a throttle chamber 5 is communicated upstream of this intake manifold 3 via an air chamber 4. An air cleaner 7 is attached via the intake pipe 6.

Further, an intake air m sensor (in the figure, a hot wire air flow meter) 8 is interposed immediately downstream of the air cleaner 7 in the intake pipe 6, and a throttle valve 5a provided in the throttle chamber 5 is provided. A throttle opening sensor 9a and an idle switch 9b for detecting a fully open throttle valve are connected to the throttle opening sensor 9a.

Furthermore, a single-point injector (hereinafter referred to as "SP injector") 10a is installed downstream of the throttle valve 5a of the intake manifold 3 collecting section, and is installed directly upstream of each intake port 2a of each cylinder of the intake manifold 3. On the side, a multi-point injector (hereinafter referred to as "rMP injector") 10b
Further, a spark plug 17 is attached to each cylinder of the cylinder head 2, the tip of which is exposed to the combustion chamber.

The above SP injector 10a and MP injector 10b
The fuel injection switching tool is different from the above MP injector 1.
The total maximum injection amount of the four 0b injectors is set larger than the maximum injection m of one SP injector 10a, and fuel injection is performed in single point injection by one SP injector 10a and multipoint injection by four MP injectors 10b. The method can be switched.

Further, the SP injector 10a and the MP injector 10b are communicated with a fuel tank 12 via a fuel passage 11, and this fuel tank 12 contains only alcohol, a mixed fuel of alcohol and gasoline, or
Only gasoline is stored, that is, fuel whose alcohol concentration changes depending on the user's refueling circumstances.

A fuel pump 13 and an alcohol concentration sensor 4 are interposed in the fuel passage 11 from the fuel tank 12 side, and the fuel passage 11 also communicates with a fuel chamber 18a of a pressure regulator 18 via a return passage 16. The downstream side of this combustion chamber 18a is communicated with the fuel tank 12.

Further, as shown by the dotted chain line in the figure, the pressure regulating chamber 18b of the pressure regulator 18 communicates with the intake manifold 3, and the pressure regulator 1
8, the differential pressure between the fuel pressure JJ in the fuel passage 11 and the pressure in the intake manifold 3 is kept constant, and the variation in the pressure in the intake manifold 3 causes the SP injector 10a and the MP injector 10 to
The fuel injection from b is controlled so as not to fluctuate.

Further, a crank rotor 21 is pivotally attached to the crankshaft 1b of the engine body 1, and a crank angle sensor 22 consisting of an electromagnetic pickup or the like for detecting the crank angle is provided on the outer periphery of the rotor 21. A cam rotor 23 is pivoted on a cam shaft 1C that rotates by 1/2 relative to the cam shaft 1C, and a cam angle sensor 24 is provided on the outer periphery of the cam rotor 23.

As shown in FIG. 3, projections 21a, 21b, and 2IC are formed on the outer periphery of the crank rotor 21. These protrusions 21a, 21b, 21c are located before the compression top dead center of each cylinder (
BTDC) θ1. It is formed at the position of θ2.03,
The protrusion 21a indicates the reference crank angle for setting the ignition timing.

The angular velocity ω is determined from the time taken to pass between 21b and 21C, and the projection 21C indicates the reference crank angle when setting the fixed ignition timing and the fuel injection start crank angle θAN.

Further, as shown in FIG. 4, cylinder discrimination protrusions 23a, 23b, and 23C are formed on the outer periphery of the cam rotor 23. The protrusion 23a is #3. It is formed at the position after the compression top dead center (ATDC>04) of the #4 cylinder, and the protrusion 23b
consists of three protrusions, the first of which is formed at the position θ5 after compression top dead center (ATDC) of the #1 cylinder, and furthermore, the protrusion 23c consists of two protrusions, the first of which is formed at a position θ6 after compression top dead center (ATDC) of #2 cylinder.

In addition, in the example shown in the figure, θ1=97° 02=65° θ
3=10", θ4-20°, θ5-5' θ6-20°, and as shown in FIG. It can be determined that the crank pulse detected by the crank angle sensor 22 is a signal indicating the crank angle of the #3 cylinder.

Also, after the cam pulse of θ5, 04 (protrusion 23a
), it can be determined that the subsequent crank pulse detected by the crank angle sensor 22 indicates the crank angle of the #2 cylinder. Similarly 66
The crank pulse after detecting the cam pulse of (protrusion 23C) indicates the crank angle of the #4 cylinder, and
When the 04 (protrusion 23a) cam pulse is detected after the θ6 cam pulse, it can be determined that the subsequently detected crank pulse indicates the crank angle of the #1 cylinder.

Further, after the cam pulse is detected by the cam angle sensor 24, it can be determined that the crank pulse detected by the crank angle sensor 22 indicates the reference crank angle (θ1) of the cylinder.

Further, a cold fJ water temperature sensor 25 faces a live cooling water passage (not shown) formed in the intake manifold 3.

Further, an 02 sensor 27 faces an exhaust pipe 26 that communicates with the exhaust port 2b of the cylinder head 2. In addition, the code|symbol 28 is a catalytic converter.

(Circuit configuration of control device) On the other hand, reference numeral 31 is a control device, and the cp of this control device 31 is
u <Central processing unit) 32, ROM33, RAM3
4, and an I10 interface 35 are connected to each other via a path line 36, and each sensor 8, 9a, 1 is connected to an input port of this I10 interface 35.
4.22, 24.25.27, and the idle switch 9b are connected, and the spark plug 17 is connected to the output port of the I10 interface 35 via the igniter 29. via SP injector 10a SMP injector 10
b1 fuel pumps 13 are respectively connected.

The ROM 33 stores a control program and fixed data, and the fixed data includes a fuel injection start crank angle map MPθAN, which will be described later.

Further, the RAM 34 stores the output signals of the respective sensors after data processing and the data processed by the CPU 32.

Further, the CPU 32 calculates the pulse width for driving the SP injector 10a or the MP injector 10b based on the various data stored in the RΔM 34 according to the control program stored in the ROM 33.

(Functional Configuration of Control Device) As shown in FIG. 1, the functions of the control device 31 related to fuel injection control include cylinder discrimination means 41, crank pulse discrimination means 42, angular velocity calculation means 43, and engine rotation speed calculation means 44. , intake air amount calculation means 45, various increase correction coefficient setting means 46, air-fuel ratio feedback correction coefficient setting means 47, alcohol concentration calculation means 48, alcohol content correction coefficient setting means 49, throttle opening comparison reference value setting means 50, Injector selection means 51, fuel adhesion coefficient setting means 52, evaporation time constant setting means 53, target air-fuel ratio setting means 54, fuel injection amount calculation means 55, SP fuel injection pulse width setting means 56, SP injector driving means 57, basic fuel Injection pulse width setting means 58, MP fuel injection pulse width setting means 59, fully open throttle region determining means 60, engine low speed region determining means 61, fuel injection start timing setting means 62, timer means 63, MP injector selection driving means 64 It consists of

The cylinder determining means 41 determines which cylinder's crank angle the crank pulse subsequently detected by the crank angle sensor 22 indicates, based on the cam pulse detected by the cam angle sensor 24 on the protrusions 238 to 23C of the cam rotor 23. Discern.

In the crank pulse discrimination means 42, the cam angle sensor 2
After the cam pulse output from the crank angle sensor 22, it is determined which of the protrusions 21a to 21c corresponds to the crank pulse output from the crank angle sensor 22.

The angular velocity calculating means 43 uses the θ1 (protrusion 21a) and 02 (protrusion 2) determined by the crank pulse discriminating means 42.
1b) is measured, and the angular velocity ω is calculated from the elapsed time t and the angle between (01-θ2) (ω-d(θ1-θ2)/dt).

The engine rotation speed calculating means 44 calculates the engine rotation speed N based on the angular velocity ω calculated by the angular velocity calculation means 43 (N-60ω/2π).

The intake air amount calculating means 45 calculates the intake air ff1Q from the output signal of the intake air m sensor 8.

The various increase correction coefficient setting means 46 reads the throttle opening (0) signal from the throttle opening sensor 9a, the 0N10FF signal from the idle switch 9b, and the cooling water temperature (Tw) signal from the cooling water temperature sensor 25, and performs acceleration/deceleration correction and full opening. Various increase correction coefficients C0EF related to increase correction, post-idle increase correction, cooling water temperature correction, etc. are set.

In the air-fuel ratio feedback correction coefficient setting means 47, 02
The output voltage of the sensor 27 is read, the output voltage of the 02 sensor 27 is compared with a preset slice level, and the air-fuel ratio feedback correction coefficient α is set by proportional-integral control.

Note that when the 02 sensor 27 is inactive, the air-fuel ratio feedback correction coefficient α is fixed at α-1, 0, and the air-fuel ratio feedback control is stopped.

The alcohol concentration calculating means 48 reads the output signal of the alcohol concentration sensor 14 and calculates alcohol 1llfA of the fuel to be supplied to the SP injector 10a and the MP injector 10b.

The alcohol content correction coefficient setting means 49 sets an alcohol content correction coefficient KAL corresponding to the alcohol concentration A calculated by the alcohol concentration calculation means 48.

The above alcohol content correction coefficient KAL is alcohol 1 [A
This is to correct the stoichiometric air-fuel ratio due to the difference in .

In other words, the stoichiometric air-fuel ratio for 100% gasoline (A-0%) is, for example, 14.9, and the stoichiometric air-fuel ratio for 100% alcohol (methanol) (△=100%) is 6°45 (in the case of ethanol, 9.01),
The higher the alcohol concentration A, the lower the stoichiometric air-fuel ratio,
Under the same engine operating conditions, it is necessary to increase the fuel injection amount.

In this example, as described later, alcohol concentration A=O%
(100% gasoline) is set based on the fuel injection a, so the above alcohol correction coefficient KAL
As shown in Fig. 8, when alcohol concentration A = O% (100% gasoline), K AL = 1.0,
As the alcohol concentration A increases, it increases continuously (in the case of methanol, when A-100%, 8L = 14.
9/6.45-2.31, for ethanol, A=10
When it is 0%, ^L-14,9/901=1.66).

Therefore, the above alcohol content correction coefficient KAL can be obtained as a function of alcohol concentration A (K^[=f(
^)).

Furthermore, it is set in advance whether methanol or ethanol is to be used as the alcohol, and a function formula or map for setting the alcohol content correction coefficient KAL is stored in the ROM 33 in advance. It is something to keep.

In the throttle opening comparison reference value setting means 50, the fuel injection amount increases according to the alcohol concentration A, as shown in FIG.
As shown in a), from single point injection by SP injector 10a to MP injector 1
In order to switch the fuel injection method to the multi-point injector 0b, the signal from the injector selection means 51 is read and it is determined whether the SP injector 10a or the MP injector 10b is currently selected. It is determined and a throttle 1721 degree comparison reference value θK is set.

When the above SP injector is selected, the throttle opening comparison reference value θK is set as a function o (
A) (−(NA) for θ), and if the above MP injector 10b is selected, the above function Q (A)
is shifted by an offset value AO (e.g., equivalent to 2.3 bits if the minimum resolution for alcohol concentration A is 1 pit) to a region where alcohol concentration A is small, and the throttle opening comparison reference value θK is set ( −g to θ
(^-AO)).

As a result, as shown in FIG. 7(b), hysteresis occurs when switching between the SP injector 10a and the MP injector 10b, and a rapid vaporization state of fuel occurs when switching between single-point injection and multi-point injection. This prevents fluctuations in engine speed and engine hunting.

The throttle opening comparison reference value θ may be set from a map using the alcohol concentration A as a parameter.

The injector selection means 51 compares the throttle opening θ detected by the throttle opening sensor 9a with the throttle opening comparison reference value θ set by the throttle opening comparison reference value setting means 50, and determines the difference between θ and θ. In this case, a calculation execution signal is output to the fuel injection calculation means 55, the SP fuel injection pulse width setting means 56, and the basic fuel injection pulse width setting means 58, the MP fuel injection pulse width setting means 59, and the throttle fully open region determining means. 601 A calculation stop signal is output to the engine low speed rotation speed range determining means 61 and the fuel injection start timing setting means 62, and the SP injector 10a is selected to execute fuel injection control by single point injection.

On the other hand, when the throttle opening degree θ is θ≧θ, the injector selection means 51 outputs a calculation stop signal to the fuel injection amount calculation means 55 and the SP fuel injection pulse width setting means 56,
Basic fuel injection pulse width setting means 58, MP fuel injection pulse width setting means 59, throttle fully open region determining means 601
An arithmetic execution signal is output to the engine low speed rotation speed range determining means 61 and the fuel injection start timing setting means 62, and the MP injector 10b is selected for fuel injection control using multi-point injection.

The fuel adhesion coefficient setting means 52 uses the throttle opening θ from the throttle opening sensor 9a and the cooling water temperature sensor 25.
Based on the cold rJ1 water UT- from Set coefficient X.

That is, the larger the throttle opening θ and the lower the cooling water temperature, the more liquid film m of fuel adheres to the inner wall of the intake manifold 3, and the amount of fuel actually taken into the engine decreases accordingly. , the fuel adhesion coefficient X is set to be large, and the smaller the throttle opening θ is and the higher the cooling water temperature is, the smaller the fuel adhesion coefficient X is set to be.

The evaporation time constant setting means 53 uses the engine speed N1, the intake air amount Q1, and the cooling water HaT- as parameters,
The evaporation time constant τ when the fuel adhering to the inner wall of the intake manifold 3 evaporates is set.

In other words, the lower the cooling water temperature T-, the more fuel adheres to the inner wall of the intake manifold 3, and the longer it takes for the adhered fuel to evaporate during fuel injection control when the intake air amount is large in the low engine speed range. Therefore, the above evaporation time constant τ is set large, and when the cooling water 11T- is high and the intake air amount is small in the engine high speed range (fuel injection tA is small), the above evaporation time constant τ is set small. do,
Correction is made to the fuel actually drawn into the engine.

In the target air-fuel ratio setting means 54, the cooling water temperature sensor 25
The target air-fuel ratio A/F is set based on the cooling water Ill signal from. This target air-fuel ratio A/F is set to the rich side when the cooling water temperature T during engine warm-up is low;
After - becomes equal to or greater than a predetermined value and warm-up is completed, the air-fuel ratio is set to the stoichiometric air-fuel ratio.

The fuel injection amount calculation means 55 sets the target air-fuel ratio for the basic fuel injection 1 based on the intake air IQ calculated by the intake air amount calculation means 45 based on the calculation execution signal 2) from the injector selection means 51. The air-fuel ratio is corrected by the various increase correction coefficients COF F set by the various increase correction coefficient setting means 46 so as to reach the target air-fuel ratio ^/F set by the means 54, and the fuel adhesion coefficient setting means 5
By using the fuel adhesion coefficient Single point injection fuel injection at %)
Gf @calculate (Gf −f (Q.

C0EF, ^/F, X, τ).

The SP fuel injection pulse width setting means 56 uses the calculation execution signal from the injector selection means 51 to convert the fuel injection 1tGf calculated by the fuel injection amount calculation means 55 to the alcohol content set by the alcohol content correction coefficient setting means 49. The air-fuel ratio is corrected by the correction coefficient KAL, and the air-fuel ratio is feedback-corrected by the air-fuel ratio feedback correction coefficient α set by the air-fuel ratio feedback correction coefficient setting means 47, and the engine 1 is Set the SP fuel injection pulse width TiS corresponding to the actual fuel injection amount per revolution. Tis −K sPx a x
G fXKAL/N), SP injector drive means 57
A drive pulse signal corresponding to the SP fuel injection pulse width TiS is output to the SP injector 10a at a predetermined timing.

The basic fuel injection pulse width setting means 58' uses the calculation execution signal from the injector selection means 51 to determine the engine rotation speed N calculated by the engine rotation speed calculation means 44.
and the intake air I calculated by the intake air amount calculation means 45.
Based on Q, Ganlin 100% (alcohol concentration 0%)
) is set as the basic fuel injection pulse width Tp of the MP injector 10b.

That is, the above basic fuel injection pulse width Tp is calculated by the following formula, Tp = KHPXQ/N KHP: stoichiometric air-fuel ratio, M, P The injection fJJ amount characteristics of the injector 10b, the number of cylinders, etc. are calculated by the reciprocal of a constant, or, It is set by a map search using the engine speed N and intake air amount Q as parameters. In the illustrated embodiment, the basic fuel injection pulse width Tp@ is set by calculation.

The MP fuel injection pulse width setting means 59 uses the calculation execution signal from the injector selection means 51 to convert the basic fuel injection pulse width Tp set by the basic fuel injection pulse width setting means 58 to the various increase correction coefficient setting means. 46
The air-fuel ratio is corrected using the various increment ω correction coefficients C0FF set in and the alcohol correction coefficient KAL set by the alcohol correction coefficient setting means 49, and the air-fuel ratio is corrected by the Feedback correction is performed using the fuel ratio feedback correction coefficient α, and the MP fuel injection pulse width TiH corresponding to the actual fuel injection interval for the MP injector 10b is set (T
iH=TpxcOEFxαxKAL).

The throttle opening range determination means 60 compares the throttle opening degree 0 detected by the throttle opening sensor 9a with a preset reference throttle opening degree θS for determining the full open range, based on the calculation execution signal from the injector selection means 51. However, if θ>O3, it is determined that the throttle is fully open.

The engine low-speed rotation speed range determination means 61 uses the calculation execution signal from the injector selection means 51 to determine the engine rotation speed N calculated by the engine rotation speed calculation means 44 and a preset reference engine rotation speed, that is, low-speed rotation. Reference engine speed Ns for number range discrimination (for example, 1
000 to 1500 rpi), and if N≦NS, it is determined that the rotation speed is in the low speed region.

The fuel injection start time setting means 62 includes a fuel injection start crank angle search means 62a1 and a fuel injection start time calculation means 62.
b1 and fuel injection start crank angle map MPθAN
Based on the calculation execution signal from the injector selection means 51, the fuel injection start crank angle retrieval means 62a selects the throttle fully open range determination means 60.
Based on the determination result of the engine low speed range determination means 61, the fuel injection start crank angle θA is determined according to the alcohol concentration A calculated by the alcohol concentration calculation means 48.
N, or the above fuel injection start crank angle θ
Set ^N to a preset fixed fuel injection start crank angle.

That is, when the throttle fully open region determining means 60 determines that the throttle is fully open, and the low engine speed region determining means 61 determines that the engine is in the low engine speed region, the alcohol calculated by the alcohol m degree calculating means 48 The fuel injection start crank angle map MPθAN is searched using IIUA as a parameter, and the fuel injection start crank angle θ^N is set.

As shown in FIG. 6, in each region of the fuel injection start crank angle map MPθAH, as the alcohol concentration A shifts from 0% to 100%, the start of fuel injection is delayed from the exhaust stroke to the intake stroke. The set fuel injection start crank angle θ^N is stored.

Note that the fuel injection start crank angle θAN is O3(
This is the crank angle with the projection 21c) as the reference (zero point).

On the other hand, if the throttle fully open region determining means 60 determines that the throttle is outside the wide open region, or if the low engine speed region determining means 61 determines that the engine is outside the low engine speed region, the fuel injection starting crank The angle θAN is set to a preset fixed fuel injection start crank angle. Note that this fixed fuel injection start crank angle is set at a position sufficient for fuel injection to end before the start of the intake stroke.

The fuel injection start time calculation means 62b calculates the fuel injection start time (time) TING from the fuel injection start crank angle θAN set by the fuel injection start crank angle search means 62a and the angular velocity ω calculated by the angular velocity calculation means 43. (TING=θAN/ω).

In the timer means 63, the fuel injection start timing calculation means 6
The fuel injection start timing (time) T ING descended at step 2b is set, and timing is started using the crank pulse detected at 03 (protrusion 21C) determined by the crank pulse discriminating means 42 as a trigger.

The MP injector selection drive means 64 receives a trigger pulse indicating the end of time measurement from the timer means 63, and instructs the MP fuel injection pulse width setting means 59 to the MP injector 10b of the corresponding cylinder determined by the cylinder determination means 41.
A drive pulse signal having the MP fuel injection pulse width Ti set in is output.

(Operation) Next, the fuel injection control procedure of the control device 31 will be explained according to the flowchart of FIG. 9.

First, in step 5101, crank pulses and cam pulses based on the output signals of the crank angle sensor 22 and cam angle sensor 24 are read, and in step 5102, cylinder discrimination is performed from the cam pulses.

Thereafter, in step 5103, a crank pulse is determined from the interruption of the cam pulse, and in step 5104, θ
The angular velocity ω is calculated from the time between detecting the 1st and 02nd crank pulses (ω=d(θ1-θ2)/dt).

Next, in step 5105, the engine rotation speed N is calculated from the angular velocity ω calculated in step 5104 (N
= (60/2π)×ω).

After that, in step 8106, the output signal of the intake air 11 sensor 8 is read to calculate the intake air iIQ, and in step 5107, the cooling water temperature Tw based on the output signal of the cooling water temperature sensor 25 and the throttle opening sensor 9a, the throttle The opening degree θ and the idle switch output are read, and the process proceeds to step 3108.

In step 8108, various increment m correction coefficients C0FF related to cooling water temperature correction, acceleration/deceleration correction, full-throttle increase correction, post-idle increase correction, etc. are set based on the information read in step 5107.

Thereafter, in step 5109, the air-fuel ratio feedback correction coefficient α is set based on the output signal of the 02 sensor 27. Further, in step 5110, alcohol concentration sensor 1
The alcohol concentration A is calculated based on the output signal of step 4, and in step 5111, the alcohol content correction coefficient is set to ^[ based on the alcohol concentration calculated in step 5110.

Then, in step 5112, it is determined whether the flag FLAG is 0, that is, whether the SP injector 10a or the MP injector 10b is currently selected, and the flag FLAG=0,
That is, if it is determined that the SP injector 10a is currently selected, the process proceeds from step 5112 to step 5113, where the throttle opening comparison reference value θK is determined as the function g(^) of the alcohol concentration A calculated in step 5110. Set from (θ=a(A)) Step 5
Proceed to 115.

On the other hand, in step 5112, the flag FLAG+0
1, that is, if it is determined that the MP injector 10b is currently selected, the process proceeds from step 5112 to step 5114, and the function Q to the alcohol concentration is determined.
Shift (A) by the offset value AO to set the throttle opening comparison reference value θK. θK = g (
A-AO)), proceed to step 5115.

In step 5115, the throttle opening degree θ read in the above step 5107 is compared with the throttle opening comparison reference value θ set in the above step 5113 or the above step 5114, and the throttle opening degree θ is In this case, it is determined that the area is a single point injection area by the SP injector 10a, and step 8116 is performed.
Proceed to.

In step 5116, a target air-fuel ratio ^/F is set based on the cooling water temperature TW, and in step 5117, based on the throttle opening θ and the cooling water temperature TI4, the fuel adhering from the SP indicator 10a to the inner wall of the intake manifold 3 is determined. Set the fuel adhesion coefficient X for

Next, in step 8118, the evaporation time constant τ of the fuel adhering to the inner wall of the intake manifold 3 is set based on the intake air ff1Q, the cooling water temperature TW, and the engine speed N, and the process proceeds to step 5119.

Then, proceed to step 5119, and proceed to step 5110 described above.
Intake air ff1Q calculated in step 6, step 8108 above
Based on the various increase correction coefficients COF F set in step 5117, the fuel adhesion coefficient x 1 set in step 5117, and the evaporation time constant τ set in step 8118, the target air-fuel ratio A/ So, calculate the fuel injection amount Gf for single point injection at 100% gasoline (alcohol concentration 0%) <Gf −f (Q, C0EF, A/F).

X, τ).

Next, in step 5120, the fuel injection mG" calculated in step 5119 is corrected using the alcohol content correction coefficient KAL set in step 5111, and the air-fuel ratio is corrected using the air-fuel ratio feedback correction coefficient α set in step 5109. The SP fuel injection pulse 2 King TiS should be set according to the actual fuel injection amount per engine revolution using the injector coefficient KSP determined by the injection amount characteristics of the SP injector 10a through feedback correction. N) Stainless steel 7S121t' SP fuel injection pulse 2 King TiS drive pulse signal is sent to the SP injector 10a at a predetermined timing.
Output to.

Then, the process advances to step 5122, and since the SP injector 10a is currently selected, the flag FLAG
Clear (FLAG=O) and exit the program.

On the other hand, in step 5115, the throttle opening θ is
In the case of ≧θ, it is determined that the area is a multi-point injection injection area by the MP injector 10b, and the process proceeds from step 5115 to step 5123, and the process proceeds to step 5123.
Engine rotation speed N calculated in step 105 and step 81 above
Set the basic fuel injection pulse width Tp for the MP injector 10b based on the intake air MQ calculated in step 06. (reciprocal of a constant), the process proceeds to step 5124.

Then, in step 5124, the above step 5123
The basic fuel injection pulse width Tp set in Step 8 above
Based on the various increase correction coefficients C0FF set in step 108, the air-fuel ratio feedback correction coefficient α set in step 5109, and the alcohol content correction coefficient set in step 5111, the actual fuel injection amount for the MP injector 10b is determined. Corresponding MP fuel injection pulse width T
Set iH (Ti14=Tl)XCOEFXαxK
AL).

Next, in step 5125, the throttle opening degree θ read in step 5107 is compared with a preset standard throttle opening degree θS for determining the fully open region, and if θ>O3, it is determined that the throttle is in the fully open region, and step The process proceeds to step 5126, and if θ≦θS, it is determined that the throttle is outside the fully open range, and the process proceeds to step 5127.

Then, when the process proceeds to step 8126, the above step 51
Compare the engine rotation speed N calculated in step 05 with the preset standard engine rotation speed NS for determining the low speed rotation speed range, and
>Ns, it is determined that it is in the middle or high speed range and step 5
If N≦NS, it is determined that the rotational speed is in the low rotation speed range, and the process proceeds to step 8128.

Proceeding to step 5127, the fuel injection start crank angle θAN is set to a fixed fuel injection start crank angle, that is, the normal injection timing.

On the other hand, in steps 8125 and 3126, it is determined that the throttle is in the fully open range and in the low speed range, and step 81
In step 28, the fuel injection start crank angle map MPθAN is searched using the alcohol concentration A calculated in step 5110 as a parameter, and the fuel injection start crank angle θAN is set.

Next, in step 5129, the fuel injection start timing T ING is calculated from the fuel injection start crank angle θAN set in the above step 5127 or the above step 5128 and the angular velocity ω calculated in the above step 5104 (TING=θAN/ω). .

Thereafter, in step 5130, the timer is set to the fuel injection start timing T ING calculated in step 5129, and in step 3131, the timer is driven using the crank pulse for detecting θ3 as a trigger signal.

Then, in step 5132, when the timer driven in step 5131 reaches the fuel injection start timing T ING, a drive pulse signal corresponding to the MP fuel injection pulse width TiM set in step 5124 is sent to the MP injector 10b of the corresponding cylinder. Output and proceed to step 5133 to set the flag FLAG (FLAG-1) to indicate that the MP injector 10b is selected.
L. Exit the program.

In this way, the fuel injection amount that increases according to the alcohol 11 degrees A is controlled by the SP injector 1 depending on the throttle opening θ.
υ control is performed by switching between single point injection by 0a and multipoint injection by MP injector 10b, and in a region where the fuel injection amount is relatively small, single point injection by SP injector 10a promotes fuel vaporization and stabilizes combustion. .

Furthermore, in the multi-point injection by the MP injector 10b, as shown in FIG. The higher the alcohol a [A, the higher the fuel injection start timing T ING set during the exhaust stroke based on the normal fixed fuel injection start crank angle. Since the vaporization of is suppressed and the vaporization time is shortened, the volumetric efficiency is improved. Furthermore, since the injection timing is varied according to the alcohol concentration A, combustion is optimized.

On the other hand, in operating ranges other than low speed rotation and high load, the injection timing is the same as in the past, that is, the fuel is injected before the start of the intake stroke, so vaporization is promoted and combustion is stabilized.

In addition, FIG. 10 shows a flowchart in the case where the fuel injection timing in the operating range other than the engine low speed rotation and high load in multi-point injection by the MP injector 10b is fixed at the fuel injection end timing.

This flowchart is different from the flowchart shown in FIG. 9 only in sections ■ to ■, in which it is determined in step 5125 that the throttle is outside the fully open range (θ≦θS), or that it is determined in step 3126 that it is outside the low speed range. (N>NS'), the program proceeds to step 5201 to read out the preset fixed injection end crank angle θ^HE, and in step 5202, the fuel injection end time T END is set to the fixed injection end crank angle read out in step 5201 above. It is calculated from θAWE and the angular velocity ω calculated in step 5104 (TEND=θANE/ω).

Here, the fixed injection end crank angle θ^HE is a crank angle with 03 (protrusion 21C) as the reference (zero point), as shown in FIG.

Further, in step 5203, the fuel injection period Tpw is changed from the MP fuel injection pulse width TiH set in step 5124.
Set.

Then, in step 5204, the fuel injection end period TEND calculated in step 5202 and the step 5
The fuel injection start timing T ING is calculated from the fuel injection period Tpw calculated in step 203 (TING - TEND -
Tpw).

Then, the process proceeds to step 3130, and the step 520 described above
Set the timer to the fuel injection start timing T ING calculated in step 4.

Although the illustrated embodiment shows a time control type fuel injection control, the present invention can also be applied to an angle control type fuel injection control.

[Effects of the Invention] As described above, according to the present invention, the throttle opening comparison reference value setting means sets the throttle opening comparison reference value according to the alcohol concentration of the fuel, and the throttle opening comparison reference value is set according to the alcohol concentration of the fuel. Compare 1f11 degrees with the throttle opening comparison reference value, and if the throttle opening is smaller than the throttle opening comparison reference value, select the single point injector installed at the intake manifold gathering part and inject fuel. On the other hand, if the throttle opening is equal to or greater than the throttle opening comparison reference value, the multi-point injector installed in the intake port of each cylinder is selected to inject fuel, so the fuel is injected according to the alcohol concentration of the fuel. The increasing required injection amount can be satisfied without using a special injector.

Further, when the multi-point injector is selected, a fully open throttle area is determined based on the throttle opening from the throttle 171 degree sensor, and
The low engine speed range is determined based on a preset standard engine speed, and if it is determined that the throttle is fully open and the engine is in the low speed range, the higher the alcohol concentration of the fuel, the higher the amount of water from the multi-point injector. Since the fuel injection start timing is set later, vaporization of alcohol fuel during low-speed rotation and high-load operation is suppressed, and
Vaporization time can be shortened.

As a result, it is possible to prevent a decrease in volumetric efficiency during engine low-speed rotation and high-load operation, to appropriately control the air-fuel ratio, and to obtain appropriate combustion, which improves operating performance and reduces exhaust emissions. It has excellent effects such as being able to make improvements.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a functional block diagram of the control device, FIG. 2 is a schematic diagram of the control system, FIG. 3 is a front view of the crank rotor and crank angle sensor, and FIG. 4 is a front view of the cam angle sensor and the cam angle sensor, Figure 5 is a time chart of fuel injection timing, Figure 6 is an explanatory diagram showing the relationship between alcohol concentration and fuel injection start timing, and Figure 7 (a) is the alcohol concentration. Explanatory diagram showing the relationship between and fuel injection method, seventh
Figure (b) is an explanatory diagram showing fuel injection switching when the throttle opening is constant; Figure 8 is a correlation diagram between alcohol concentration and alcohol content correction coefficient; Figure 9 is a flowchart showing the fuel injection control procedure; 11 and 11 show other embodiments, FIG. 10 is a flowchart showing a fuel injection control procedure, and FIG. 11 is a time note of fuel injection timing. 9a... Throttle opening sensor 10a... Single point injector 10b.
...Multi-point injector 22...Crank angle sensor 44...Engine speed calculation means 50...Throttle opening comparison standard value setting means 51...
- Injector selection means 60...Throttle full open range discrimination means 61...Engine low speed rotation speed range discrimination means 62...Fuel injection start timing setting means θ...Throttle opening OK...Throttle opening comparison standard Value A...Alcohol concentration N...Engine speed T ING...Fuel injection start timing

Claims (1)

[Scope of Claims] Throttle opening comparison reference value setting means for setting a throttle opening comparison reference value according to the alcohol concentration of fuel, and throttle opening comparison reference value setting between the throttle opening from a throttle opening sensor and the throttle opening comparison reference value. When the throttle opening is smaller than the throttle opening comparison reference value set by the means, the single point injector installed in the intake manifold assembly is selected and fuel is injected. On the other hand, if the throttle opening is greater than the throttle opening comparison reference value,
an injector selection means for selecting a multi-point injector disposed in an intake port of each cylinder and injecting fuel; a fully open throttle region determining means for determining a fully open throttle region based on the opening degree; and when the multi-point injector is selected by the injector selection means, determining a low engine speed region based on a preset reference engine speed. If the engine low speed rotation speed range determining means determines that the throttle is in the full throttle range and the engine low speed rotation speed range determining means determines that the engine is in the low engine speed range, the alcohol concentration of the fuel is high. A fuel injection control device for an alcohol engine, comprising: fuel injection start timing setting means for delaying and setting the fuel injection start timing from the multi-point injector.