JPH0361642A - Fuel injection controller for alcohol engine - Google Patents

Abstract

PURPOSE:To improve the operation performance by carrying out the selection to an intake group injector or inside-cylinder injector on the basis of the results of the judgement of a throttle fully opening region judging means, engine low revolution speed region judging means and a high alcohol concentration judging means. CONSTITUTION:When a judging means 52 judges the throttle opening degree outside the fully opening region, or a judging means 53 judges the number of revolution of an engine outside the low revolution speed region, or a judging means 54 judges the low or intermediate alcohol concentration, an injector selecting condition judging means 55 selects an injector selecting driving means 60 through a selector means 56, and injection is carried out from an injector 10 installed onto an intake manifold. While, if it is judged that the throttle opening degree is in the fully opening region, and the engine revolution speed is in a low revolution speed region, and the alcohol concentration which is detected by an alcohol concentration sensor 15 is a high alcohol concentration, an injector selecting driving means 61 for the inside-cylinder injection is selected, and injection is carried out from an injector 17 for the inside-cylinder injection. Thus, the air-fuel ratio can be controlled properly.

Description

[Detailed Description of the Invention] [Industrial Application Field J] The present invention provides fuel injection during low-speed rotation and high-load operation between an injector installed in the intake system and an injector installed in the cylinder according to the alcohol concentration of the fuel. The present invention relates to a fuel injection control device for an alcohol engine that switches to one side.

[Prior art and problems to be solved by the invention] In recent years, fuel vehicles that can be operated using only gasoline, only alcohol, or a mixture of gasoline and alcohol have been developed.
F V (Flexible Fuel Vchic
An alcohol engine has been developed for

Praise the alcohol in the fuel of the alcohol engine above! 1
(Content rate) is 0% due to user circumstances when refueling.
(gasoline only) to 100% (alcohol only), and the stoichiometric air-fuel ratio varies depending on the alcohol concentration in the fuel.
As disclosed in the publication, it is necessary to appropriately set the air-fuel ratio and ignition timing variably according to the alcohol concentration in the fuel.

Additionally, in the past, fuel injection timing was generally set to be completed within the intake pipe and before the start of intake in order to promote vaporization and stabilize combustion; Since the volumetric expansion coefficient of fuel is approximately three times that of gasoline, the decrease in volumetric efficiency due to fuel vaporization increases as the alcohol concentration in the fuel increases. If alcohol is directly injected into the intake pipe before the intake stroke regardless of the concentration, 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 exhaust emissions.

Particularly, in a low-speed rotation, high-load operation region 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 significantly, and the above-mentioned problems become conspicuous.

Therefore, for example, as in the fuel injection control device disclosed in Japanese Patent Application Laid-Open No. 61-160551, by setting the injection timing of the fuel injected from the injection nozzle provided on the intake boat to the latter half of the intake stroke, alcohol can be vaporized. Techniques for suppressing this and preventing a decrease in volumetric efficiency are generally known.

However, the intake inertia during low-speed rotation and high-load operation is small, and even if fuel is injected in the latter half of the intake stroke, thermal expansion due to vaporization is likely to occur in the intake boat while the fuel is passing through and in the cylinder before the intake valve closes. , it is not possible to completely suppress the decrease in volumetric efficiency.

[Object of the Invention] The present invention has been made in view of the above circumstances, and even in low-speed rotation and high-load operation, the volumetric efficiency does not decrease.
The air-fuel ratio can be controlled appropriately, improving driving performance,
An object of the present invention is to provide a fuel injection control device for an alcohol engine that can 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 includes a throttle fully open region determining means for determining a fully open throttle region based on an output signal of a throttle opening sensor; An engine rotation speed calculation means for calculating the engine rotation speed based on the output signal of the angle sensor; and an engine low rotation speed range determination means for determining the engine low speed rotation speed range based on the engine rotation speed calculated by the engine rotation speed calculation means. , high alcohol concentration determining means for determining high alcohol concentration based on the output signal of the alcohol concentration sensor, the fully open throttle region determining means, the low engine speed range determining means, and the high alcohol concentration determining means based on the determination results. , an injector switching condition determining means for determining a switching condition for operating either the injector provided in the intake system or the in-cylinder injector provided in the cylinder, and based on the determination result of the injector switching condition determining means, The injector is provided with a switching means for driving one of the injector and the in-cylinder injector.

[Function] In the above configuration, first, it is determined whether or not the throttle is in the fully open region based on the output signal of the throttle opening sensor.

Furthermore, the engine speed is decreased based on the output signal of the crank angle sensor, and it is determined whether the engine speed is in a low speed range.

Furthermore, it is determined whether the alcohol concentration is high based on the output signal of the alcohol concentration sensor.

If it is determined that the throttle opening is outside the full open range, the engine speed is outside the low speed range, or the alcohol concentration is low or medium, the driving conditions for operating the injector installed in the intake system are established. It is determined that In addition, when it is determined that the throttle opening is in the full open range, the engine speed is in the low speed range, and the alcohol concentration is high, the switching conditions for operating the in-cylinder injector installed in the cylinder are set. It is determined that it has been established.

Then, based on the above discrimination result, the above injector and
One of the in-cylinder injectors is switched and driven.

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

The drawings show one embodiment of the present invention, and FIG. 1 is a functional block diagram of a fuel injection control device, and FIG. 2 is a fuel injection! l) 1 i!
Schematic diagram of the illI Ill system. Figure 3 is a front view of the crank rotor and crank angle sensor. Figure 4 is a front view of the cam rotor and cam angle sensor. Figure 5 is a time chart of fuel injection timing. Figure 6 is a fuel injection timing chart. FIG. 7, a flowchart showing the injection control device, is a correlation diagram between alcohol concentration and alcohol content correction coefficient.

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

Further, an intake air amount sensor (a hot wire air flow meter in the figure) 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 connected to a throttle valve 5a provided in the throttle chamber 5. An opening sensor 9a and an idle switch 9b for detecting all throttle valves are connected.

Further, an injector 10 is disposed immediately upstream of each intake boat 2a of each cylinder of the intake manifold 3. Furthermore, for each cylinder of the cylinder head 2,
An in-cylinder injector 17 is attached whose tip is exposed to the combustion chamber.

Further, the injector 10 and the in-cylinder injector 17 are communicated with a fuel tank 13 via a fuel passage 19, and a fuel pump 14 and an alcohol concentration sensor 15 are interposed in this fuel passage 19 from the fuel tank 13 side. There is.

The fuel tank 13 stores only alcohol, a mixed fuel of alcohol and gasoline, or only gasoline, that is, fuel whose alcohol concentration changes depending on the user's refueling situation.

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 in opposition to the crankshaft 1b. A cam rotor 23 is pivotally attached to a camshaft IC that rotates 172 times with respect to 1b, 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 21c are formed on the outer periphery of the crank rotor 21. As shown in FIG. These protrusions 21a, 21b, 21c are located before the compression top dead center of each cylinder (
BTDC) θ1. θ2. It is formed at the position θ3,
The protrusion 21a indicates the reference crank angle for setting the ignition timing.

The angular velocity ω is calculated from the passage between 21b & i, and the protrusion 21c is the reference crank when setting the fixed fuel injection start crank angles θ^Nl and θAN2 of the injector 10 or the in-cylinder injector 17. Show the corner.

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 located after the compression top dead center of the #3.94 cylinder (
ATDC) 04, and the protrusion 23b is composed of three protrusions, the first of which is formed at the position θ5 after compression top dead center (ATDC) of the #1 cylinder, and the protrusion 23C is composed 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°, θ2−65°, 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, θ4 (protrusion 23a
> is detected, 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 θ6
The crank pulse after detecting the cam pulse of the (protrusion 23c) indicates the crank angle of the #4 cylinder, and
When a cam pulse of θ4 (protrusion 23a) is detected after the cam pulse of θ6, it can be determined that the crank pulse detected thereafter 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 in question).

Furthermore, a cooling water temperature sensor 2 is installed in a cooling water passage (not shown) forming a riser formed in the intake manifold 3.
5 is coming.

Furthermore, an 02 sensor 27 is placed facing the exhaust pipe 26 communicating with the exhaust boat 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 pass line 36, and each sensor 22, 24 .
8, 9a, 25, 27, 15, and the idle switch 9b are connected to the output port of the I10 interface 35, and the injector 10, in-cylinder injector 17, and fuel pump 14 are connected via the drive circuit 38.
are connected to each other.

In the above ROM33! ! 1tI11 programs and the like are stored.

Further, the RAM 34 stores the output signals of the respective sensors after data processing and the data subjected to att calculation processing by the CPtJ 32.

Roughly speaking, the CPU 32 calculates the pulse width and the like for driving the injector 10 based on various data stored in the RAM 34 in accordance with the control program stored in the ROM 33.

(Functional configuration of fuel injection control means) As shown in FIG. Shut-off means 44, intake air ff1R output means 45, basic fuel injection amount setting means 46, various increase correction coefficient setting means 47
, air-fuel ratio feedback correction coefficient setting means 48, alcohol S degree calculation means 49, alcohol content correction coefficient setting means 50, fuel injection ffi setting means 51, throttle fully open region determining means 52, engine low speed rotation speed region determining means 53,
High alcohol concentration determination means 54, injector switching condition determination means 55, switching means 56, fuel injection start crank angle selection means 57, fuel injection start timing determination means 58, timer means 59, injector selection drive means 60, for direct injection It is composed of an injector selection drive means 61.

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 pulses detected by the cam angle sensor 24 on the protrusions 23a 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 calculates θ1 (protrusion 21a) and θ2 (protrusion 2) determined by the crank pulse discriminating means 42.
1b), and calculates the angular velocity ω from the elapsed time t and the included angle of (θ1-θ2).
Based on the angular velocity ω calculated by the angular velocity calculation unit 43, the engine rotational speed calculation unit 45 calculates the intake air IQ from the output signal of the intake air amount sensor 8.

The basic fuel injection amount setting means 46 sets the basic fuel injection amount Tp based on the engine rotation speed N calculated by the engine rotation speed calculation means 44 and the intake air flaQ calculated by the intake air amount calculation means 45.

That is, the above basic fuel injection m'rp is expressed by the following formula, Tp-K
xQ/N K: Calculated using a constant or set by map search using engine speed N and intake air fiQ as parameters. In the illustrated embodiment, the basic fuel injection amount Tp is set by calculation.

Here, the basic fuel injection t141Tp is assumed to be at 100% gasoline (alcohol concentration 0%).

The various increase correction coefficient setting means 47 reads the throttle opening (θ) signal from the throttle opening sensor 9a, the 0N10FF signal from the idle switch 9b, and the cooling water temperature (TV) signal from the cooling water temperature sensor 25, and performs acceleration/deceleration correction and full throttle adjustment. Various increase correction coefficients C0FF 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 48, 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 49 reads the output signal of the alcohol 81 degree sensor 15 and calculates the alcohol concentration A of the fuel to be supplied to the injector 101 or the in-cylinder injector 17.

The alcohol fractionation positive coefficient setting means 49 sets the alcohol fractionation positive coefficient KAL corresponding to the alcohol 1aA calculated by the alcohol concentration calculation means 48.

The alcohol fraction correction coefficient KAL is used to correct the stoichiometric air-fuel ratio due to a difference in alcohol concentration.

That is, the stoichiometric air-fuel ratio for 100% gasoline (A-0%) is 14.9, as an example, and the stoichiometric air-fuel ratio for 100% alcohol (methanol) (A = 100%) is 6.45 (in the case of ethanol, 9.01),
The higher the alcohol concentration, the lower the stoichiometric air-fuel ratio.
Under the same engine operating conditions, it is necessary to increase the fuel injection amount.

Therefore, in this embodiment, the basic fuel injection amount Tp is set to the alcohol concentration A-0% (Ganlin 100%) as described above.
Since it is set as , the above alcohol fractionation positive coefficient K
AL is alcohol IIfmA as shown in FIG.
-0% (100% gasoline), KAL=1.
0, the alcohol concentration increases continuously as the alcohol concentration A increases (in the case of methanol, when A-100%, K A
L-14,9/6.45 #2.31, in the case of ethanol, A-100% K AL-14,9/9.01
#1.66).

Therefore, the alcohol fractionation positive coefficient KAL can be determined as a function of the alcohol concentration (KAL-
Chi (A)〉.

Note that the alcohol fractionation positive coefficient KAL may be set from a map using the alcohol concentration A as a parameter.

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

The fuel injection amount setting means 51 sets the basic fuel injection Q'1ffiT[) set by the basic fuel injection amount setting means 46 as follows.
Various increase correction coefficients C0FF set by the various increase correction coefficient setting means 47, and alcohol fraction correction coefficient K set by the alcohol fraction correction coefficient setting means 50''c.
The air-fuel ratio is corrected by AL, and the fuel injection amount Ti is set by feedback correction by the air-fuel ratio feedback correction coefficient α set by the air-fuel ratio feedback correction coefficient setting means 4B (Ti −Tp xCOEFxαxKA
L).

The throttle fully open region determining means 52 compares the throttle opening θ detected by the throttle opening sensor 9a with a preset reference throttle opening θS for determining the fully open region, and if θ>θS, the throttle is fully open. It is determined that

The engine low speed range discrimination means 53 uses the engine speed N calculated by the engine speed calculation means 44 and the preset reference engine speed Ns for low speed range discrimination.
(For example, compare 1000 to 1500 rpm+u, and if N≦Ns, it is determined that the rotation speed is in the low speed region.

High alcohol i! The degree determination means 54 uses the alcohol concentration A calculated by the alcohol concentration calculation means 49 and the preset high alcohol degree determination standard 11 degrees As.
(for example, 30%), and if A≧As,
It is determined that the alcohol concentration is high.

The injector switching condition determining means 55 determines whether the injector 1
0 and the in-cylinder injector 17 are to be operated.

However, the throttle fully open region discriminating means 52 distinguishes the throttle fully open region (θ〉O8), the engine low speed rotation speed region discriminating means 53゛C determines the engine low speed rotation speed region (N≦NS), and high alcohol. Concentration determination means 5
If it is determined in step 4 that the alcohol concentration is high (A≧As>), it is determined that the in-cylinder injector drive condition is satisfied; otherwise (θ≦05..N>NS, or A<As
'), it is determined that the injector drive condition on the intake system side is satisfied.

The switching means 56 outputs an operation signal to one of the injector selection drive means 60 and the in-cylinder injection injector selection drive means 61 based on the determination result by the injector drive condition determination means 55, and outputs a stop signal to the other (i). In addition, fuel injection start crank angle +i selection means 57
Outputs a hein injector selection signal.

The fuel injection start crank angle selection means 57 selects one of the exhaust stroke fixed fuel injection start crank angle OANl and the fixed fuel injection start crank angle θAN2 after intake valve closing, based on the injector selection signal from the switching means 56.

The above-mentioned exhaust stroke fuel injection start crank angle 0AN1 indicates the injection start crank angle of the injector 10, and as shown in Fig. 5, it is determined and set in advance through experiments etc. so that the fuel injection is completed before the intake valve opens. has been done.

In addition, the fixed fuel injection start crank angle θAN2 after the intake valve is closed indicates the injection start crank angle of the in-cylinder injector 17, and as shown in FIG. 5, as a reference for the crank angle O3 during the combustion stroke, The angle is set to start fuel injection at the beginning of the compression stroke after the intake valve closes.

The fuel monitoring start timing determining means 58 determines the fuel injection [t
Fuel injection II is determined from the exhaust stroke fixed fuel injection start crank angle θANI selected by the first crank angle selection means 57, or from the fixed fuel injection start crank angle θAN2 after the intake valve is closed and the angular velocity ω calculated by the angular velocity calculation means 43.
I start time (time) T1NG1 or T1NG
2 (T INGI-θAN1/ω, or T 1NG2-θ to N2/ω).

Then, in the immediate means 59, at the start of the fuel injection, I'll
+11IT at the start of fuel injection calculated by the tI output means 58
lNG1,.

Alternatively, T1NG2 is set, and timing is started using the crank pulse that detects O3 (protrusion 21C) determined by the crank pulse determining means 42 as a trigger.

In the injector selection driving means 60, the switching means 56
When an operation signal is output from the timer means 59, the injector 10 of the corresponding cylinder determined by the cylinder determination means 41 receives a trigger pulse indicating the end of time measurement from the timer means 59;
Fuel injection %J set by the fuel injection 1ffi setting means 51
A drive pulse corresponding to ffiTi is output.

When the in-cylinder injector selection driving means 61 receives an operation signal from the switching means 56, the cylinder discriminating means 41 receives a trigger pulse indicating the end of time 51 from the timer means 59. The fuel injection amount setting means 51 is applied to the in-cylinder injector 17 of the identified cylinder.
A drive pulse corresponding to the fuel injection 04fdTi set in is output.

(Work 11) Next, the control procedure of the fuel injection control means 31a having the above configuration will be explained according to the flowchart shown in FIG.

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 cam pulse interruption, and in step 5104,
θ1. Calculate the angular velocity ω from the elapsed time between detecting the crank pulse of θ2 (ω=d(θ1-02)/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 bond sensor 8 is read and the intake air ff1Q is calculated, and in step 5
In step 107, the engine rotation speed N calculated in step 5105 above, and the intake air □Q calculated in step 8106 above.
Set basic fuel injection ff1Tp based on (TI)
-to-Q/N K: constant).

Next, in step 8108, the cooling water tu is determined based on the output signals of the cooling water temperature sensor 25 and the throttle opening sensor 9a.
TW, throttle opening θ, and idle switch output are read, and in step 5109, the above step 81 is read.
Based on the information read in step 08, various additional 61-minute correction coefficients C0FF related to cooling water temperature correction, acceleration/deceleration correction, full-throttle increase correction, ground distance correction after idling, etc. are set.

Thereafter, in step 5110, the air-fuel ratio feedback correction coefficient α is set based on the output signal of the 02 sensor 27. Also, in step 5111, alcohol concentration sensor 1
In step 5112, the alcohol content correction coefficient KA is calculated based on the alcohol concentration A calculated in step 5111.
Set L.

Then, in step 5113, the basic fuel injection faTl) set in step 3107, described in step 51
Based on the various increase correction coefficients COF set in step 09, the air-fuel ratio feedback correction coefficient α set in step 5110, and the alcohol correction coefficient KAL set in step 5112, the fuel injection rate Ti is calculated from the following equation.

Ti −Tp xCOEFxαx) (^ [Next, in step 5114, the throttle opening θ read in step 3108 above is compared with a preset standard throttle opening θS for determining the full open area, and if θ>θS, It is determined that the throttle is fully open, and the process proceeds to step 5115, where θ≦θ
In the case of S, it is determined that the throttle is outside the fully open area and the process proceeds to step 5.
117 Heji Jump Zuru.

Then, when the process proceeds to step 5115, the above step 51
Compare the engine rotation speed N calculated in step 05 with the preset standard throttle opening degree NS for determining the low speed rotation speed range.
> In the case of NS, it is determined that it is outside the low speed rotation range and the process proceeds to step 51.
If N≦NS, it is determined that the rotation speed is in the low speed range and the process advances to step 8116.

In step 3116, the alcohol concentration A calculated in step 5111 is compared with a preset standard concentration As for determining high alcohol concentration, and if A < As, the alcohol concentration of the fuel is determined to be low or medium. Step 5
The process proceeds to step 117, and if A≧As, it is determined that the alcohol concentration is high and the process proceeds to step 8118.

Proceeding to step 5117, the exhaust stroke fixed fuel injection start crank angle θAN1, that is, the normal injection timing is selected.

Then, in step 5119, the exhaust stroke fixed fuel injection start crank angle θAN selected in step 5117 is determined.
From I and the angular velocity ω calculated in step 5104 above,
The fuel injection start timing TlNG1 of the injector 10 is calculated (T INGI-θANI /ω).

Thereafter, in step 5120, the fuel injection start timing T[NG1 calculated in step 5119 is set in a timer, and in step 5121, the timer is driven using the crank pulse detected as 03 as a trigger signal.

Then, in step 5122, when the timer driven in step 5121 reaches the fuel injection start timing T1NG1, the injector 10 of the corresponding cylinder is
A drive pulse corresponding to the fuel injection ff1Ti set in step 113 is output.

On the other hand, in step 5114, it is determined that the throttle is in the fully open region (θ>θS), and in step 5115, it is determined that the engine is in the low speed rotation speed region (N≦Ns), and in step 81
When it is determined in step 16 that the alcohol concentration is high (A≧As) and the process proceeds to step 8118, a fixed fuel injection start crank angle θAN2 is selected after the intake valve is closed, and step 5123
The fixed fuel injection start crank angle θ^N2 after intake valve closing selected in step 3118 above and step 51 above.
The fuel injection start timing TlNG2 of the in-cylinder injector 17 is calculated from the angular velocity ω calculated in step 04 (Tr
NG2-θ^N2/ω).

Thereafter, in step 5124, the fuel injection start timing T1NG2 calculated in step 5123 is set in a timer, and in step 5125, the timer is driven using the crank pulse detected as 03 as a trigger signal.

Then, in step 5126, when the timer driven in step 5125 reaches the fuel injection start timing T1NG2, a drive pulse corresponding to the fuel injection maximum Ti set in step 5113 is applied to the in-cylinder injector 17 of the corresponding cylinder. Output.

As a result of the above, as shown in Fig. 5, when the engine operating state is in the fully open throttle region and low speed region, and the fuel has a high alcohol concentration, in-cylinder injection occurs at the beginning of the compression stroke after the intake valve closes. Since the fuel is injected from the fuel injector 17, volumetric efficiency is good, the air-fuel ratio can be optimized, and driving performance and exhaust emissions can be improved.

On the other hand, in operating ranges and alcohol concentrations other than those mentioned above, 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 the illustrated embodiment, time control type fuel injection control is shown, but the present invention can also be applied to angle control type fuel injection control.

[Effects of the Invention] As described above, according to the present invention, there is provided a fully open throttle fl range discriminating means for discriminating a fully open throttle range based on an output signal of a throttle opening sensor, and an engine detecting means based on an output signal of a crank angle sensor. [11 engine rotation speed calculation means for calculating the engine rotation speed, engine low speed rotation speed range determination means for determining the engine low speed rotation speed range based on the engine rotation speed calculated by the engine rotation speed calculation means, and the output of the alcohol concentration sensor. Based on the determination results of the high alcohol m degree determination means for determining high alcohol concentration based on the signal, the throttle all W4 range determination means, the engine low speed range determination means, and the high alcohol concentration determination means, the intake system an injector switching condition determining means for determining switching conditions for operating either the provided injector or the in-cylinder injector provided in the cylinder; and based on the determination result of the injector switching condition determining means, Since it is equipped with a switching means for driving one side of the in-cylinder injector, it is possible to prevent a decrease in volumetric efficiency during low-speed rotation and high-load operation under high alcohol concentration, and to maintain an appropriate air-fuel ratio. It is possible to control and obtain proper combustion,
It has excellent effects such as improved driving performance and improved exhaust emissions.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, with FIG. 1 (a functional block diagram of the fuel injection control system), FIG. 2 (a schematic diagram of the fuel injection control system), and FIG. Front view, Figure 4 is a front view of the cam rotor and cam angle sensor,
Figure 5 shows time charts 1 to 6 of fuel injection timing.
The figure is a flowchart showing the fuel injection control procedure, and FIG. 7 is a correlation diagram between alcohol concentration and alcohol content correction coefficient. 9a... Throttle opening sensor, 10... Indicator I
15... Alcohol concentration sensor, 17... In-cylinder injector, 22... Crank angle sensor,
44...Engine speed calculation means, 52...Throttle fully open region discrimination means, 53...Engine low speed rotation speed region discrimination means, 54...High alcohol concentration discrimination means・5
5...Injector switching condition determination means, 56°...Switching means, A...Alcohol concentration, N...Engine speed. Figure 3 Figure 7

Claims (1)

[Scope of Claims] Throttle fully open range determining means for determining a fully open throttle range based on an output signal of a throttle opening sensor; engine speed calculating means for calculating an engine speed based on an output signal of a crank angle sensor; A low engine speed range determining means for determining a low engine speed range based on the engine speed calculated by the engine speed calculating means; and a high alcohol concentration determining means for determining a high alcohol concentration based on an output signal of an alcohol concentration sensor. , an injector provided in the intake system based on the determination results of the fully open throttle region determination means, the engine low speed range determination means, and the high alcohol concentration determination means;
an injector switching condition determining means for determining a switching condition for operating the in-cylinder injector provided in the cylinder; 1. A fuel injection control device for an alcohol engine, comprising switching means for driving one of the two.