JPH03100342A - Fuel injection control device for alcohol engine - Google Patents

Abstract

PURPOSE:To prevent deterioration of volumetric efficiency by setting fuel injection timing, such that the higher is the alcohol concentration of fuel the more the timing is delayed, when an engine low speed and a throttle fully-opened region are decided. CONSTITUTION:In a fuel injection period setting means 54, various corrections are added in a setting means 51 to a basic fuel injection amount calculated by an engine speed N and a suction air amount Q in a setting means 46, and a fuel injection amount further a fuel injection period is set. On the other hand, in a fuel injection timing setting means 55, being based on the engine speed and a throttle opening discriminated by a discriminating means 52, fuel injection end timing is variably set in a calculating means 55b through a setting means 55a, further fuel injection start timing is variably set in a calculating means 55c from the fuel injection period. Here in the case of a low engine speed and a throttle fully-opened region, the fuel injection start timing is set in a manner wherein the higher is the concentration of alcohol the more the start timing is delayed. Thus by suppressing vaporization, volumetric efficiency can be prevented from deteriorating.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a system for varying fuel pressure and fuel injection timing based on the alcohol concentration of the fuel when the engine operating state is in the low engine speed and fully open throttle region. , relates to a fuel injection control device for an alcohol engine that prevents a decrease in volumetric efficiency.

[Problems to be solved by conventional technology and inventions] In recent years, due to worsening fuel conditions and demands for exhaust purification, systems that can simultaneously use alcohol as an alternative fuel in addition to conventional gasoline have been put into practical use. Vehicles such as cars equipped with this system (Flexible F
(hereinafter referred to as rFFVJ)
In addition to gasoline, it is now possible to run on a mixture of alcohol and gasoline, or on alcohol alone.

The engine of this FFV is, for example, JP-A-58-285
As disclosed in Publication No. 57, the alcohol concentration in the mixed fuel of alcohol and gasoline is detected by an alcohol sensor, and the fuel injection amount is corrected based on this alcohol concentration and controlled to maintain the stoichiometric air-fuel ratio. There is.

Additionally, in the past, fuel injection timing was generally set to complete within the intake pipe and before the start of intake in order to promote vaporization and stabilize combustion; The volumetric expansion coefficient of gasoline is approximately three times that of gasoline, and as the alcohol concentration in the fuel increases, the volumetric efficiency decreases due to fuel vaporization. If the fuel is injected into the intake pipe, air-fuel ratio control cannot be performed properly due to a decrease in volumetric efficiency due to vaporization, resulting in a problem of decreased driving performance and worsening of exhaust emissions.

Particularly, in the low engine speed and fully open throttle operation range where the amount of fuel injected is large and the fuel remains for a sufficient time for vaporization in the intake pipe, the volumetric efficiency is significantly reduced, and the above-mentioned problems become conspicuous.

[Object of the Invention] The present invention has been made in view of the above circumstances, and is capable of appropriately controlling the air-fuel ratio without reducing the volumetric efficiency even when the engine operating state is at low engine speed and the throttle is fully open. The present invention aims to provide a fuel injection control device for an alcohol engine that can improve driving performance and 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 an engine rotation speed calculation means for calculating an engine rotation speed based on an output signal of a flank angle sensor; an engine operating state determining means for determining the engine operating state based on the engine speed calculated by the engine speed calculating means and the throttle opening data; If it is determined that the throttle is fully open, the fuel alcohol mf! a fuel pressure adjusting means that sets a higher fuel pressure as the alcohol concentration is higher based on I, and changes a pressure discrimination value of a variable fuel pressure regulator in accordance with the fuel pressure set value; and an operating state parameter detecting means. a fuel injection amount setting means for setting a fuel injection amount based on a detection signal of the engine; and when the engine operation determining means determines that the engine is in a low rotational speed and throttle fully open region, the fuel pressure setting value set by the fuel pressure adjusting means; Fuel injection set by the above fuel injection amount setting means! l) When the fuel injection period setting means for setting the fuel injection period of the injector based on J et al. , and fuel injection timing setting means for delaying and setting the fuel injection timing.

[Operation 1] With the above configuration, the engine rotation speed calculation means calculates the engine rotation speed based on the output signal of the flank angle sensor, and the engine operation state determination means determines the engine operation state based on the engine rotation speed and throttle opening data. is determined.

When the engine operating state determining means determines that the engine operating state is in a low engine speed and fully open throttle region, the fuel pressure adjusting means sets a higher fuel pressure as the alcohol concentration of the fuel is higher. The pressure control value of the variable fuel pressure regulator is changed in accordance with the value.

Furthermore, if the fuel injection Ql setting means sets the fuel injection amount based on the detection signal of the operating state parameter detecting means, and the engine operating state determining means determines that the engine is in a low rotational speed and the throttle is in the fully open region, the fuel injection period is set. The means sets the fuel injection period of the injector based on the fuel pressure setting value and the fuel injection amount, and the fuel injection timing setting means sets the fuel injection timing to be delayed as the alcohol concentration of the fuel is higher. .

Therefore, if the engine operating state is low engine speed,
] In the case of full throttle range, the higher the alcohol concentration of the fuel, the higher the fuel pressure, which shortens the fuel injection period, and delays the fuel injection timing, which reduces the fuel vaporization time and prevents a decrease in volumetric efficiency. be done.

Examples of the invention] Hereinafter, the present invention will be described 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 control device, FIG. 2 is a schematic diagram of a fuel injection control system, and FIG. 3 is a schematic diagram of a fuel injection control system.
The figure is a front view of the crank rotor and crank angle sensor.
The figure is a front view of the cam rotor and cam angle sensor, Figure 5 is a time chart of fuel injection timing, Figure 6 (a) is an explanatory diagram without showing the fuel pressure settings for alcohol concentration, and Figure 6 (b) is a front view of the cam rotor and cam angle sensor.
) is a conceptual diagram of the fuel pressure map, FIG. 7 is a conceptual diagram of the fuel injection period map, FIG. 8 is a conceptual diagram of the fuel injection end crank angle map, FIG. 9 is a flowchart showing the fuel injection timing setting procedure, and FIG. 11 is a flowchart showing the fuel injection interrupt process, and FIG. 11 is a flowchart showing the fuel pressure control procedure.

(Configuration) In FIG. 2, reference numeral 1 is an alcohol engine for FFV, and the figure shows a 4-cylinder horizontally opposed engine. An intake manifold 3 is connected to an intake boat 2a formed in the cylinder head 2 of this alcohol engine 1.
A throttle chamber 5 is communicated upstream of the intake manifold 3 via an air chamber 4, and an air cleaner 7 is attached to the upstream side of the throttle chamber 5 via an intake pipe 6.

Further, an intake air amount sensor (a hot wire air meter 70 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 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.

Further, an injector 10 is disposed immediately upstream of each intake boat 2a of each cylinder of the intake manifold 3. Furthermore, a spark plug 17 is attached to each cylinder to the cylinder head 2, the tip of which is exposed to the combustion chamber.

Further, the injector 10 is communicated with a fuel tank 12 via a fuel supply path 11, and the fuel tank 12
In the fuel tank, fuels with different alcohol concentrations A (%) are stored depending on the user's refueling situation, such as alcohol only, a mixed fuel of alcohol and gasoline, or only gasoline.

A fuel pump 13 and an alcohol concentration sensor 14 are interposed in the fuel supply passage 11 from the fuel tank 12 side, and a variable fuel pressure regulator 18 is further interposed in the return passage 16.

The variable fuel pressure regulator 18 includes, for example, a regulator body 19 and an electric actuator 20 fixed to the regulator body 19. The fuel chamber 1 of the regulator body 19 communicates with the return passage 16.
The downstream side of 9a is connected to the fuel tank 12, and the valve 1
The fuel chamber 1 is connected by a diaphragm 19b having a diameter 9e.
A pressure regulating chamber 19c separated from 9a is communicated with the intake manifold 3. And the above injector 1
The pressure difference between the zero fuel pressure (fuel pressure) and the pressure inside the intake manifold 3 is kept constant, and the fuel injection amount from the injector 10 is controlled so as not to fluctuate due to fluctuations in the pressure inside the intake manifold 3.

Further, in the variable fuel pressure regulator 18, a receiving portion 20b of a spring 19d that biases the diaphragm 19b is fixed to the tip of the plunger 1/20a of the electric actuator 20.
0, for example, by controlling the voltage, the plunger 20a
is displaced and the diaphragm 19b by the spring 19d
By changing the biasing force to the valve 19e, the amount of fuel leaked by the valve 19e, that is, the amount of fuel returned, is varied, thereby making it possible to vary the fuel pressure.

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 pivotally attached to a camshaft 1C that rotates by 1/2 relative to the camshaft 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 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 transit time between the protrusions 21b and the protrusion 21c reduces the reference crank angle when setting the fixed ignition timing and the fuel injection end 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 θ4 after the compression top dead center (ATDC) 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°, θ2−65″, θ
3=10"θ4=20' θ5=5゜θ6=20
For example, when the cam angle sensor 24 detects a cam pulse of θ5 (protrusion 23b), the crank angle sensor 24
It can be determined that the crank pulse detected at step 2 is a signal indicating the crank angle of the #3 cylinder.

Also, after the cam pulse of θ5, θ4 (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 θ6
The crank pulse after detecting the cam pulse of (protrusion 23G) 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 standard crank angle (θ1) of the corresponding cylinder.

Further, a cold fJI water temperature sensor 25 is provided facing a cooling water passage (not shown) through a riser formed in the intake manifold 3.

Further, an 02t7 sensor 27 faces the exhaust pipe 26 that communicates with the exhaust bows i to 2b of the cylinder head 2.

Note that the reference numeral 28 is a catalyst inverter.

(Circuit configuration of control device) On the other hand, reference numeral 31 is a control device, which includes a CPU (central processing unit @) 32, ROM 33, RA
The M34 and the I10 interface chair 35 are connected to the U via the pass line 36, and the alcohol concentration sensor 14 and each sensor 8 constituting the driving state parameter detection means 31b are connected to the input port of the I10 interface 35. .9a, 22.24, 25, 27 and the idle switch 9b are connected, and the above I10
The spark plug 17 is connected to the output boat of the interface 35 via an igniter 29, and the injector 10, fuel pump 13, and electric actuator 20 of the fuelable pressure regulator 18 are connected via a drive circuit 38. each connected.

The ROM 33 stores control programs and fixed data. As for the fixed data, it is J! fuel injection period map MPTPW, fuel injection end crank angle map MPθ^N1 fuel pressure map MPPF.

There is also fixed injection end crank angle melon (θAN) data.

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

Further, the CPU 32 calculates the pulse width 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 control device) As shown in FIG. 1, the functions related to fuel injection control of the control system @31 include cylinder discrimination means 41, crank pulse discrimination means 42, angular velocity calculation means 43, engine rotation speed calculation. means 44, intake air amount calculation 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 concentration calculation means 49, alcohol content correction coefficient setting means 50, Fuel injection amount setting means 51, engine operating state determining means 52
, fuel pressure adjustment means 53, fuel injection period setting means 54, fuel injection timing setting means 55, and injector selection/driving means 56.

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 uses the θ1 (protrusion 21a) and 02 (protrusion 2) determined by the crank pulse discriminating means 42.
1b) is measured, and the angular angle ω is calculated from this elapsed time t and the angle of (θ1-02) ((,)=d(θ1-02). 02))
.

t The engine rotation speed calculation 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 calculation means 45 calculates the intake air GtQ from the output signal of the intake air amount sensor 8.

The basic fuel injection amount setting means 46 calculates H(T= KxQ/N.

K: the reciprocal of a constant based on the stoichiometric air-fuel ratio, the number of cylinders, etc.) or by a map search using the engine speed N and intake air amount Q as parameters to set the basic fuel injection ωTP.

In this case, the above basic fuel injection Di M T p has a fuel aluminium content A of 0% (gasoline 100%).
).

The various incremental e 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 ('l) signal from the cooling water temperature sensor 25, and performs acceleration/deceleration correction. , various increase correction coefficients c related to full open ground correction, post-idle increase correction, cold U1 water temperature correction, etc.

Set EF.

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 calculation means 49 reads the output signal of the alcohol concentration sensor 14 and calculates the alcohol concentration of the fuel to be supplied to the injector 10.

The alcohol content correction coefficient setting means 5o sets an alcohol content correction coefficient KAL corresponding to the alcohol degree S calculated by the alcohol concentration calculation means 49.

The above alcohol content correction coefficient KAL is the alcohol concentration A
This is to correct the stoichiometric air-fuel ratio due to the difference in . That is, the stoichiometric air-fuel ratio in 100% gasoline (alcohol concentration 0%) is - for example, 14.9, and the stoichiometric air-fuel ratio in alcohol (methanol > 100%) is 6.45.
(9.01 in the case of ethanol), and as the alcohol concentration increases, the stoichiometric air-fuel ratio decreases, and under the same engine operating conditions, it is necessary to increase the fuel injection amount.

Therefore, in this embodiment, since the basic fuel injection lTp is set as alcohol concentration A=O% (gasoline 100%) as described above, the above alcohol content correction coefficient is
[is alcohol concentration A1 = 0% (gasoline 100%)
In the case of ^ = 1.0, the alcohol concentration increases continuously as the alcohol concentration A increases. It is determined from the function to 11 degrees alcohol (K^[=chi(^)), and the deviation in the stoichiometric air-fuel ratio due to the alcohol concentration A is corrected by this alcohol content correction coefficient.

In this case, the alcohol content correction coefficient ^[ is, for example, if the stoichiometric air-fuel ratio in the case of 100% gasoline is 14.9, and the stoichiometric air-fuel ratio in the case of 100% alcohol (methanol) is 6.45, KAL= 2.3 (KAL = 1.7' for ethanol), and under the same operating conditions, the fuel injection amount for 100% alcohol is approximately twice the fuel injection Q% for 100% gasoline. becomes.

Note that the alcohol content correction coefficient KAL may be set from a map using the alcohol concentration Δ as a parameter.

The fuel injection period setting means 51 adjusts the basic fuel injection fijTp set by the basic fuel injection amount setting means 46 to the various increase correction coefficients C0EF set by the various increase correction coefficient setting means 47 and the alcohol content. The air-fuel ratio is corrected by the alcohol content correction coefficient set by the correction coefficient setting means 50, 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 48, and the fuel injection amount Ti is (Ti = Tp XC0EFXαXKAL).

The engine operating state determination means 52 uses the engine rotation speed N calculated by the engine rotation speed locking means 44 and the preset reference engine rotation speed Ns for determining the low speed rotation speed region.
(for example, 1000 to 1500 rpm), and also compares the throttle opening θ detected by the throttle opening sensor 9a with a preset throttle opening θ3 for determining the full open range, and determines that NSN 3 N and θ>θS In this case, it is determined that the engine is at low speed and the throttle is fully open.
N>NS.

Alternatively, in the case of θ≦θS, it is determined that the engine speed is outside the low-speed engine speed and throttle fully open range.

The fuel pressure adjusting means 53 includes a fuel pressure setting means 53a, a fuel pressure map MPPF, and an actuator driving means 53b.In the fuel pressure setting means 53a, when the engine operating state determining means 52 determines that the engine operating speed is low and the throttle is out of the fully open range, A reference position signal is output to the actuator drive means 53b.

On the other hand, when the engine operating state determining means 52 determines that the engine is in a low rotational speed and the throttle is fully open, the alcohol concentration A expressed by the alcohol 1Ii 1 degree calculating means 49 is determined from the fuel pressure map MPPF using the expressed alcohol concentration as a parameter. Search for the fuel pressure setting 1jj PF, and reduce the fuel pressure setting value PFO previously stored at a predetermined address in the RAM 34 from this fuel pressure setting value P to obtain the pressure control value ΔP. ΔPF = PF - PFO). This pressure control ill (ilJΔP" is outputted to the actuator drive means 53b, and the fuel pressure set value PF is outputted to the fuel injection period setting means 54.

The pressure control value ΔPF is a control amount that drives the plunger 20a of the actuator 20 in the variable fuel pressure regulator by a protrusion amount ρ from the current position, and when the plunger 20a of the actuator 20 is displaced,
The compression of the spring 19d changes. As a result, the position of the valve 19e changes, the valve leakage, that is, the fuel return from the return passage 16 changes, and as shown in FIG.
The fuel pressure is varied from the fuel pressure at 100% gasoline to the maximum fuel pressure at alcohol concentration A=100% (0% gasoline).

Generally, the amount of fuel injected from a nozzle such as the injector 10 is proportional to the 1/2 power of the fuel pressure, so if the opening time of the injector 10 is kept constant, the amount of fuel injection Ti is
To double it, just quadruple the fuel pressure. In reality, the fuel pressure map MPPF calculates the alcohol concentration A as shown in FIG. A fuel pressure set value PF determined through experiments or the like is stored as a parameter.

Fuel injection 11) 1 period setting means 54 sets the fuel injection 61 when the engine operating state determining means 52 determines that the engine speed is low and the throttle is out of the fully open range and the plunger 20a of the actuator 1-20 is at the reference position. Means 5
The fuel injection period TP- is set from the fuel injection amount Ti set in step 1, TPW=Ti/ING, [NG: fuel injection amount per injector elastic valve opening time], and the engine operating state determining means 52 determines that the engine is rotating at low speed. If it is determined that the throttle is in the fully open region, a fuel injection period map MFTP- is created using the fuel injection ftTi set by the fuel injection setting means 51 and the fuel pressure set value PF set by the fuel pressure setting means 53a''c as parameters. Search and set the fuel injection period TP.

As shown in FIG. 7, the fuel injection period map M P TPt4 stores the fuel injection period TIQI determined from the characteristics of the injector 10 at the address of a grid whose parameters are the fuel pressure set value pF and the fuel injection amount T1. This fuel injection period TP- is the period during which the engine 1 injects the fuel 1tTi at the fuel pressure regulated to the fuel pressure set value PF.
It is stored as data of the valve opening time of 0, that is, the fuel injection pulse width.

The fuel injection timing setting means 55 includes a fuel injection end crank angle setting means 55a, a fuel injection end crank angle map MPθAN, a fuel injection end time calculation means 55b1, a fuel injection tJ4 start time 11Il calculation means 55C, and a timer means 55d. End crank angle setting means 5
5a, the engine operating state determining means 52 determines that the engine is at low speed and the throttle is fully open Ijiii! If it is determined that it is outside, the fixed injection end crank angle (θAN) data stored in the ROM 33 is read out. Further, when it is determined that the engine operating state determining means 52'c is in the low engine rotation speed and fully open throttle region, the fuel injection end crank angle map MPθ^ is calculated using the alcohol concentration A calculated by the alcohol concentration calculating means 49 as a parameter.
The fuel injection end crank angle θAN is set from N.

The above fuel injection end crank angle map MPθAI4 is
As shown in FIG. 8, the fuel injection crank angle OAH is stored in an address with the alcohol concentration Δ as a parameter, and this fuel injection end cranking angle θAN indicates that the alcohol concentration A is A=0% (gasoline 100%). ), the crank angle is set at which fuel injection ends during the intake stroke @ (before the intake valve opens), and the alcohol concentration A is A = 100%.
(100% alcohol), the crank angle is set to end fuel injection just before the end of the intake stroke, and as the alcohol concentration A increases from 0% to 100%, the crank angle is set to a retarded value (100% alcohol). (See Figure 6).

The fuel injection end timing n output means 55b calculates the fuel injection end crank angle θAN set by the fuel injection end crank angle setting means 55a, or the fixed injection end crank angle θA14, and the angular velocity ω calculated by the angular velocity calculation means 43. Calculate the fuel injection end time TEND from (
TE140=θAN/ω).

The fuel injection start time calculation means 55G calculates the fuel injection end time T calculated by the fuel injection end time calculation means 55b.
Fuel injection is performed by subtracting the fuel injection period TPW set by the fuel injection period setting means 54 from END! :) +1 at the start of l
Calculate 1TING (TING=TEN[)-TPW
).

The timer means 55d calculates the fuel injection start time T1. calculated by the fuel injection start time calculation means 55c. NG is set and θ3 determined by the crank pulse determining means 42.
Timing is started using the crank pulse detected by the protrusion 21C as a trigger.

In the injector selection/driving means 56, upon receiving the trigger pulse indicating the end of time measurement from the above-mentioned timer means 55dd,
A drive signal having a pulse width of the fuel injection period TP- set by the fuel injection period setting means 54 is output to the injector 10 of the cylinder determined by the cylinder determination means 41.

(Operation) Next, the operation of the embodiment with the above configuration will be explained based on L4 with reference to the flowcharts of FIGS. 9 to 11.

(Fuel injection timing setting) In the interrupt routine for setting the fuel injection timing shown in FIG. 9, first, in step 5101, the crank angle sensor 22
, read the crank pulse and cam pulse from the cam angle sensor 24, respectively, and proceed to step 5102 to select the cylinder #i (4 in the embodiment) where the fuel injection timing should be set next.
Since it is a cylinder, i=1 to 4) is determined.

For example, as described above, when the 04 cam pulse is detected after the 06 cam pulse, the crank pulse θ1 detected after that indicates the crank angle of the #1 cylinder,
At this time, the next cylinder to set the fuel injection timing is #
4 (see the time chart in FIG. 5).

Thereafter, in step 5103, a crank pulse is determined from the interruption of the cam pulse, and in step 5104, θ
1. The angular velocity ω is calculated from the time during which the crank pulse of θ2 is detected (ω=d(θ1−θ2)/dt).

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

Then, in step 5toer, the output signal of the intake air sensor 8 is read and intake air ff1Q is calculated, and step 51
07, the engine rotation speed N1 calculated in step $105 above, the intake air calculated in step 8106 above...Q1
．． : Based on this, set the basic fuel injection amount To when the alcohol concentration is -0% (Tp = -Q/NK; the reciprocal of a constant based on the stoichiometric air-fuel ratio, number of cylinders, etc.).

Next, in step 8108, the coolant mTW, throttle opening θ, and idle switch output are read, and in step 5109, based on the information read in step 8108, coolant temperature correction, acceleration/deceleration correction, full-open amount increase correction, and post-idle amount increase are performed. Various increase correction coefficients C0FF related to correction etc.
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, with switch 5111, alcohol concentration sensor 1
The alcohol concentration A is determined based on the output signal of step 4, and in step 5112, an alcohol content correction coefficient KAL is set based on the alcohol concentration A calculated in step 5111.

Then, in step 5113, the basic fuel angle injection LfaTp set in step 5107,
Based on the various increase correction coefficients CO set in step 09, the air-fuel ratio feedback correction coefficient α set in step 5110r, and the alcohol correction coefficient KALl set in step 5112, the fuel injection fikTi is calculated from the following equation.

Ti = ToxcOEFxaxKAL Next, in step 5114, the preset standard throttle opening degree θS for determining the open area is read from the ROM 33 h+, and compared with the throttle opening degree θ read in step 8108,
If θ>O3, it is determined that the throttle is fully open and the process proceeds to step 5115. If 0≦θS, it is determined that the throttle is outside the fully open area and the process jumps to step 8116.

In step 5115, the preset reference engine speed NS for determining the low speed Φλ number range is read from the ROM 33, and the engine speed N calculated in step 5105 is read out from the ROM 33.
If N>NS, it is determined that the engine speed is outside the low speed rotation speed range and the process proceeds to step 5116, and if NSNs, it is determined that the engine speed is within the low speed speed range and the process proceeds to step 3120.
Proceed to.

In steps 5114 and 3115, the engine operating state is determined to be low engine speed and out of the throttle range, and when the process proceeds to step 8116, the engine operating state identification flag FLAG is cleared (FLAG←φ), and the process proceeds to step 5117. .

In step 5117, the fixed injection end crank angle θAn is read from a predetermined address in the ROM 33, and in step 81
At step 18, the fixed fuel injection DJ end crank angle θAN is divided by the angular velocity ω calculated at step 5104 above to calculate the fuel injection end time T END (TEND = θ
AN/ω), proceed to step 5119 and perform step 5 above.
The fuel injection period TP- is set based on the fuel injection tJ4ffiT+ set in step 113 (TPW=Ti/ING
), proceed to step 5125.

On the other hand, if it is determined in steps 5114 and 5115 that the engine operating condition is in the low engine speed and fully open throttle region, the process proceeds to step 5120, and the engine operating condition identification flag FALG is set.FALG←1)
, proceed to step 5121.

In step 5121, a fuel pressure map MP is created using the alcohol m degree calculated in step 5111 as a parameter.
PF is searched to set the fuel pressure set value pF, and further, in step 5122, the fuel injection end crank angle map MPθAN is searched using the alcohol concentration A as a parameter to set the fuel injection end crank angle θAN.

Then, in step 5123, the fuel injection end flank angle 0^N set in step 5122 is divided by the angular velocity ω calculated in step 5104 to calculate the fuel injection end time TEND (TEND=θAN/ω), and step Proceed to 5124.

Proceeding to step 5124, the fuel injection period map MPTPW is searched using the fuel injection ωTi calculated in step 5113 and the fuel pressure set value PF set in step 5121 as parameters, and the fuel injection period TP- for the injector 10 is set. , proceed to step 5125.

In step 5125, the fuel injection period TPW set in step 5119 is subtracted from the fuel injection end time TEND calculated in step 3118, or the fuel injection end time calculated in step 5123 is calculated.
The fuel injection start timing ING is calculated by subtracting the fuel injection period T set in step 5124 from T[ND (TING = TEND - TP).

And step 3126'C-1 above step 512
6-C Set the calculated fuel injection start timing T ING to the timer #i (1-1 to 4 since there are 4 cylinders in this example) corresponding to the cylinder #i determined in step 5102 above, and execute the routine. finish.

In addition, here, the higher the alcohol 111 degrees A of the fuel at low engine speed and fully open throttle region,
At the start of fuel injection based on θ3 pulse! If 1TING becomes long and only one timer is used, 191TING at the start of fuel injection in adjacent combustion cylinders overlaps and cannot be handled. Therefore, a plurality of timers are used depending on the number of cylinders i. For example, if it is determined in step 5102 that the cylinder to which the fuel injection timing should be set next is cylinder #4, the corresponding timer #4 is set to In step 5125, the fuel injection start timing t) determined is set.

(Fuel injection) Fig. 10 shows θ3 (BTDCloo in the example)
) is a routine showing a fuel injection interrupt process activated by a crank pulse that detects
1, the timer #i set in the above-mentioned interrupt routine for setting the fuel injection timing is triggered by the first 03 pulse after the fuel injection start timing T ING is set in the timer #i, and starts measuring time.

Then, when the fuel injection start timing T ING is reached, in step 5202, a drive signal having a pulse width of the fuel injection period TPW set in the above-mentioned fuel injection timing setting interrupt routine is output to the injector 10 of the corresponding cylinder #I. and fuel is injected.

(Fuel Pressure iI Control) On the other hand, the fuel pressure control routine shown in FIG.
1, read the engine operating state identification flag FLAG,
It is determined whether the engine operating state is in the low engine speed and fully open throttle region.

When FLAG=φ, that is, the engine low speed rotation speed,
When the throttle is outside the fully open range, the process advances to step 5302, and the plunger 20a of the actuator 20 is set to the reference position (ρ-〇).

In addition, if FLAG=1 in step 5301 above, that is, when the engine speed is low and the thrower 1 to thrower open region, the process proceeds to step 5303, and RΔM34
The previously stored fuel pressure setting PFO is read from a predetermined address, and the process advances to step 5304.

In step 5304, the fuel pressure map MPPF is searched using the alcohol concentration A of the fuel as a parameter, and a fuel pressure set value PF is set.

Next, the process proceeds to step 3305, and the step 530 described above is performed.
The previous fuel pressure setting value PEO read in step 3 and step 5 above
At step 304, a pressure control value ΔPF is calculated from the fuel pressure set value PF set this time (ΔPF=PF−PFO).

Then, in step 8306, the actuator 20 is driven by the plunger protrusion amount 1 corresponding to the pressure control value ΔPF calculated in step 3305 to regulate the fuel pressure to a predetermined fuel pressure, and in step 5307, the fuel pressure is stored at a predetermined address in the RAM 34. Previous fuel pressure setting value PFO
is updated with the current fuel pressure set value PF.

Note that when the routine is performed for the first time, the plunger 20a of the actuator 20 is set to II? Initialize set to position (ρ=O).

As a result, the engine operating state changes to low engine speed,
In the case of a fully open throttle region, the higher the alcohol concentration of the fuel, the higher the fuel pressure control value PF is set based on the fuel pressure map MPPF.
8, the protrusion amount 1 of the plunger 20a of the actuator 20 increases, pushing up the spring 19d, and the fuel pressure control region based on the differential pressure response of the diaphragm 19b is offset by the protrusion amount 1, and as a result, the injector 10
The fuel pressure applied to will increase.

As shown in FIG. 5, when the engine operating state is in the low engine speed and fully open throttle region, the higher the alcohol concentration A of the fuel, the shorter the fuel injection period TPW is by increasing the fuel pressure PF. By delaying the fuel injection timing without changing the fuel injection amount per cycle, the fuel vaporization time is reduced and the volumetric efficiency is improved.

Also, depending on the alcohol concentration A, the fuel injection period TPW,
Since the fuel pressure PF and fuel injection timing are varied, combustion is optimized.

On the other hand, in the operating range outside the low engine speed and fully open throttle range, the fuel injection period TP14 and fuel pressure P are the same as before.
F. Since the fuel is injected at the correct timing, vaporization is promoted and combustion is stabilized.

Although the illustrated embodiment shows fuel injection control using a time control method, fuel injection control using an angle control method is also possible. The present invention can also be applied to error control.

Moreover, the actuator 20 may be a stepping motor.

Furthermore, in this embodiment, the basic fuel injection ff1TP is set as 100% gasoline, and this is set as 100% gasoline.
Although correction is made using the alcohol content correction coefficient KAL in response to 1 degree, the invention is not limited to this, for example,
When setting the basic fuel injection ff1Tl), correction may be made for the alcohol WaA of the fuel, or the basic fuel injection ff1Tp is set as the alcohol concentration Δ-100% and this is corrected for the alcohol II IU A. You can do it like this.

In this embodiment, the fuel injection start timing TING is set using four timers corresponding to each cylinder of the four-cylinder engine. For example, if the fuel cylinder order is #
In the case of #1→#3→#2→#4, different timers may be used for adjacent cylinders, and #1. For #2 cylinder, the first timer, #3. #2 for cylinder #4
The timer may be used to set the fuel injection start timing T [NG, and the present invention is not limited to four-cylinder engines.

Furthermore, in this embodiment, throttle opening data based on the output signal of the throttle opening sensor is used when determining the full throttle opening.
Basic fuel injection υ or fuel injection +14 as melon data
It is also possible to use a full-throttle switch to determine whether the throttle is fully open.
You may also do so.

[Effects of the Invention] As described above, according to the present invention, when the engine operating state is in the low engine speed and fully open throttle region,
Since the fuel injection timing, fuel injection period, and fuel pressure are variably set according to the alcohol concentration of the fuel,
It is possible to suppress the vaporization of alcohol fuel and shorten the vaporization time when the engine is running at low speed and the throttle is fully open.

As a result, it is possible to prevent a decrease in volumetric efficiency at low engine speeds and when the throttle is fully open, and it is possible to properly control the air-fuel ratio, as well as to obtain appropriate combustion, improving driving performance and providing a pleasant atmosphere. Excellent effects such as being able to improve the J mission can be achieved.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a functional block diagram of a control device, FIG. 2 is a schematic diagram of a fuel injection control system, and FIG. 3 is a schematic diagram of a fuel injection control system.
The figure is a front view of the crank rotor and crank angle sensor.
The figure is a front view of the cam rotor and cam angle sensor, Figure 5 is a time chart of fuel injection timing, Figure 6 (a) is an explanatory diagram showing the fuel pressure setting with respect to alcohol temperature, and Figure 6 (b) is a front view of the cam rotor and cam angle sensor.
) is a conceptual diagram of the fuel pressure map, FIG. 7 is a conceptual diagram of the fuel injection period map, FIG. 8 is a conceptual diagram of the fuel injection end crank angle map, FIG. 9 is a flowchart showing the fuel injection timing setting procedure, and FIG. 11 is a flowchart showing the fuel injection interrupt process, and FIG. 11 is a flowchart showing the fuel pressure control procedure. 9a... Throttle opening sensor, 10... Injector, 14... Alcohol concentration sensor, 18... Variable fuel pressure regulator, 22... Crank angle sensor, 31b... Operating state parameter detection means, 44...
- Engine rotation speed calculation means, 51...Fuel injection amount setting means, 52...Engine operating state determination means, 53...
-Fuel pressure adjustment means, 54...Fuel injection period setting means, 5
5...Fuel injection timing setting means, A...Al depth level, PF...Fuel pressure setting value, ΔPF...Pressure control value, TEND...Fuel injection end timing, Ti.
...Fuel injection start, T ING...Fuel injection start timing,
TP14...Fuel injection period.

Claims (1)

[Claims] Engine speed calculation means for calculating the engine speed based on the output signal of the flank angle sensor, and engine operation based on the engine speed calculated by the engine speed calculation means and throttle opening data. an engine operating state determining means for determining the state; and when the engine operating state determining means determines that the engine operating state is in the low engine speed and throttle full range, based on the alcohol concentration of the fuel, the higher the alcohol concentration, the higher the alcohol concentration; , a fuel pressure adjustment means for setting a high fuel pressure and changing a pressure discrimination value of a variable fuel pressure regulator in accordance with the fuel pressure setting value; and a fuel pressure adjustment means for setting a fuel injection amount based on a detection signal of the operating condition parameter detection means. When the injection amount setting means and the engine operation determining means determine that the engine is in a low rotational speed and the throttle is in the fully open region, the fuel pressure setting value set by the fuel pressure adjusting means and the fuel injection amount set by the fuel injection amount setting means are determined. a fuel injection period setting means for setting a fuel injection period of the injector based on the engine operating state determination means;
1. A fuel injection control device for an alcohol engine, comprising: a fuel injection timing setting means that delays the fuel injection timing as the alcohol concentration of the fuel increases when it is determined that the throttle is in a fully open region.