JPH0370859A - Fuel flow controller of alcohol engine - Google Patents

Abstract

PURPOSE:To normally obtain proper fuel flow in response to fuel alcohol concentration without using a large fuel pump by setting required fuel flow of fuel pumps communicated with a fuel tank based on calculated alcohol concentration by an alcohol concentration calculation means. CONSTITUTION:Fuel alcohol concentration is calculated by an output signal of an alcohol concentration sensor 13. Required flow of fuel pumps 14a, 14b which is communicated with a fuel tank is set by a pump flow set means 42 based on alcohol concentration. Required maximum fuel flow which varies by fuel alcohol concentration is normally and properly obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel flow control device for an alcohol engine that variably sets the fuel flow 8 of a fuel pump depending on the alcohol content of the fuel.

[Prior art and problems to be solved by the invention] In recent years, fuel cell systems that can be operated on either gasoline fuel, alcohol fuel, or a mixed fuel of gasoline and alcohol have been developed.
F V (Flexible Fuel Vehicle
An alcohol engine has been developed for

This alcohol engine for FFV, for example,
As disclosed in Japanese Patent No. 8-28557, the alcohol concentration of the fuel is detected by an alcohol fuel sensor, and the fuel injection 1) Jffi is corrected based on this alcohol concentration to maintain the stoichiometric air-fuel ratio. .

However, the stoichiometric air-fuel ratio when using alcohol (fuel with an alcohol concentration of 100%) is approximately 1/2 of that when using gasoline (alcohol concentration: 0%),
The higher the alcohol concentration of the fuel, the lower the stoichiometric air-fuel ratio. Therefore, in the alcohol engine for FFV, under the same engine operating conditions as a conventional gasoline engine, when the alcohol concentration of the fuel is 100% (gasoline 0%), the alcohol concentration is 0% (gasoline 100%).
), the fuel injection amount is approximately twice as much as in the case of 2), and correspondingly, the capacity of the fuel pump that supplies fuel to the injector (the amount of oil delivered by the fuel pump, the fuel flow rate) is approximately 2 Must be doubled.

Generally, the amount of oil fed by the fuel pump in a normal gasoline engine, that is, the required maximum fuel flow rate, is set with some margin relative to the maximum fuel injection capacity of the engine.

In an FFV alcohol engine, if the required maximum fuel flow rate of the fuel pump is set based on 100% alcohol fuel, even if 100% gasoline fuel is used,
The engine will be supplied with fuel several times the maximum flow rate that it actually requires, and the minimum fuel consumption area (gasoline 10
In the case of 0% idle operation), excessive supply occurs and the fuel return A is very large, which not only reduces energy loss but is also unfavorable from the viewpoint of noise control.

On the other hand, in the alcohol engine for FFV, if the required maximum fuel flow rate of the fuel pump is kept the same as that of the normal gasoline engine mentioned above, the maximum fuel consumption area (
When the alcohol content is high (for example, when the engine is operated at high speed and under high load with 100% alcohol), the fuel pressure may decrease due to insufficient supply of oil from the fuel pump, and the necessary fuel injection rate may not be obtained.

In addition, many of the fuel pumps currently on the market are designed to match the oil flow rate of gasoline engines, and are large enough to supply the maximum oil flow rate (fuel flow rate) required during high-speed rotation and high-load operation with 100% alcohol. Few pumps are commercially available, and even if such a large fuel pump were to be adopted, there would still be problems with bill mounting.

[Object of the Invention] The present invention has been made in view of the above circumstances, and it is possible to reduce energy loss and achieve low noise, and also to avoid insufficient fuel diversion without using a large fuel pump.
It is an object of the present invention to provide a fuel flow control device for an alcohol engine that can always obtain an optimal fuel flow rate depending on the alcohol concentration of the fuel and that allows easy installation of a fuel pump.

[Means for Solving the Problems] In order to achieve the above object, the fuel flow control device for an alcohol engine according to the present invention includes an alcohol concentration calculation means for calculating the alcohol concentration of the fuel based on an output signal of an alcohol concentration sensor; The apparatus further includes pump flow rate setting means for setting the required fuel flow rate of a plurality of fuel pumps communicating with the fuel tank based on the alcohol concentration calculated by the alcohol concentration calculation means.

[Function] In the above configuration, the alcohol concentration of the fuel is determined based on the output signal of the alcohol concentration sensor, and based on this alcohol concentration, the necessary discharge of the plurality of fuel pumps communicating with the fuel tank is set, and the alcohol concentration of the fuel is determined. Always optimally secure the required maximum fuel flow rate, which varies depending on the concentration.

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

The drawings show one embodiment of the invention, and FIG. 1 shows a fuel flow 11i.
1. Functional block diagram of the I11 control device, Figure 2 is a schematic diagram of the engine control system, Figure 3 is an explanatory diagram showing the relationship between the required maximum fuel flow rate for alcohol concentration and the required fuel flow Q of the fuel pump, and Figure 4. The figure is a flowchart showing the fuel meteor control procedure.

(Structure) In FIG. 2, reference numeral 1 is an alcohol engine for FFV, and the figure shows a horizontally opposed engine.

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

Further, an intake air & 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 f.
7i! An a-sensor 9a and an idle switch 9b for detecting a fully open throttle valve are connected.

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 with its tip exposed to the combustion chamber is attached to the throat 2 of the cylinder for each cylinder.
It is being

Further, reference numeral 13 denotes a fuel tank, which is set to have a relatively large capacity in consideration of the fuel consumption when the alcohol level is high. In addition, due to the increased capacity, the fuel tank 13
A saddle-shaped relief part 13a for overhanging a propeller shaft, rear differential, etc. is formed at the center of the bottom of the fuel tank 13.
It is divided into left and right parts at a.

This fuel tank 13 stores alcohol-only fuel, gasoline-only fuel, or a mixed fuel of alcohol and 3-soline, that is, fuel with an alcohol content that changes depending on the user's circumstances at the time of refueling. ing.

Further, the left and right bottom volume portions 13b, 1 of the fuel tank 13 are
3c are connected to fuel pumps 14a and 14b of the same size, respectively.

The fuel pumps 14a and 14b each have the same capacity as a fuel pump in a normal gasoline engine. Furthermore, the fuel passages 19a communicating with the discharge sides of the respective fuel pumps 14a, 14b are joined in the middle and then communicated with the respective injectors 10. Roughly speaking, an alcohol concentration sensor 15 is interposed slightly downstream of the merged portion of the fuel passages 19a.

Further, one end of a fuel return passage 19b is communicated with the fuel passage 19a immediately upstream of the injector, and the other end of this fuel passage 19b is inserted into the upper part of the tank from above the fuel tank 13, and its discharge port 19c , 19c are branched into two parts, and are respectively faced above the bottom volume parts 13b and 13c.

On the other hand, an operating chamber 16a of the pressure regulator 16 is interposed in the fuel return passage 19b, and a pressure regulating chamber 16c is partitioned from this operating chamber 16a via a diaphragm 16b.
The above intake manifold 3 as shown by the dotted chain line in the figure.
is communicated with.

The pressure regulator 16 keeps the pressure difference between the fuel pressure of the injector 10 and the pressure inside the intake manifold 3 constant, and the fluctuation in the pressure inside the intake manifold 3 causes the fuel injection from the injector 10 to be controlled. Q・I: Control so that i'r does not fluctuate.

Further, a crank rotor 21 is pivotally attached to the crankshaft 1b of the engine 1, and a crank angle sensor 22 consisting of an electromagnetic pickup or the like for detecting the crank angle and engine rotational speed is provided on the outer periphery thereof.

Furthermore, a water drying sensor 25 is installed in a cooling water passage (not shown) that is similar to the riser formed in the intake manifold 3. ! I am being treated.

Further, an 02 sensor 27 is provided at a gathering portion of the exhaust pipes 26 communicating with the exhaust boat 2b of the cylinder head 2. Note that the number 28 is the 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
tJ (central processing unit) 32, ROM33, RAM
34. The I10 interfaces 35 are connected to each other via a path line 36, and the input ports of the I10 interfaces 35 are connected to the respective sensors 8.9 and 8.9.
a, 15.22.25°27, and an idle switch 9b are connected.

Further, the spark plug 17 is connected to the output port of the I10 interface 35 via an igniter 29, and the injector 10. Further, fuel pumps 14a and 14b are respectively connected.

The ROM 33 stores control programs and fixed data. The RAM 34 stores the output signals of the respective sensors after data processing and the data processed by the CPtJ 32.

Furthermore, in accordance with the control program stored in the ROM 33, the CPtJ32 calculates the fuel injection amount, ignition timing, required fuel flow rate by the fuel pump, etc. according to the alcohol concentration of the fuel, based on various data stored in the RAM 34. do.

(Functional Structure of Control Device) As shown in FIG. ing.

The alcohol concentration calculation means 41 reads the output signal of the alcohol concentration sensor 15 and calculates the alcohol concentration A of the fuel.

The pump flow rate setting means 42 sets the required fuel flow rate for the fuel pumps 14a and 14b, that is, the pump rotation speed Np, as a function of the alcohol concentration A calculated by the alcohol 81 degree calculation means 41 (Np - f (A)).
.

As mentioned above, as the alcohol concentration A increases, the stoichiometric air-fuel ratio decreases, and it is necessary to increase the fuel injection amount.
Correspondingly, the required maximum fuel flow rate, which is set based on the maximum fuel injection amount at a certain alcohol concentration A, also increases.

Since the fuel pumps 14a and 14b have the same capacity Φ, the fuel flow rate (
The required maximum fuel flow rate) is twice the flow rate discharged from each fuel pump 14a (14b). Therefore, the required fuel flow rate (pump rotation speed) by each fuel pump 14a, 14b corresponding to the above required maximum flow rate is 1 of the above required maximum flow rate.
/2.

According to experiments, the relationship between the alcohol concentration and the required maximum fuel flow rate increases as the alcohol concentration A of the fuel increases, and the required maximum fuel flow rate changes linearly as shown by the solid line in Figure 3. Therefore, the fuel pumps 14a, 1
The required fuel flow rate of fuel pump 4b also changes linearly as shown by the broken line in FIG. 3, and therefore, the pump rotational speed Np of fuel pumps 14a and 14b can be determined as a function of the alcohol concentration.

The pump rotational speed Np corresponding to the required fuel flow rate of the fuel pumps 14a, 14b may be set by searching a map determined in advance through experiments using the alcohol concentration A as a parameter.

The fuel pump drive means 43 outputs a drive signal corresponding to the pump rotation speed Np set by the pump flow rate setting means 42 to the fuel pumps 14a, 14b.

When the fuel pumps 14a, 14b are driven by a DC motor, the fuel pump driving means 43 outputs a voltage corresponding to the pump rotation speed Np set by the pump flow rate setting means 42.

Further, when the fuel pump 14 is driven by an AC motor, the fuel pump driving means 43 outputs a frequency corresponding to the pump rotation speed Nl).

(Control Operation) Next, the fuel flow rate control procedure by the control device 31 is performed in a fourth manner.
The explanation will be given according to the flowchart shown in the figure.

The program shown in FIG. 4 is an interrupt program that is executed every predetermined time or every predetermined cycle from when the power of the control device 31 is turned on until it is turned off (from engine start to engine stop). be.

First, in step 5101, the alcohol concentration sensor 15
Read the output signal and calculate the alcohol concentration of the fuel.
Proceed to step 5102.

In step 5102, the fuel pump 14a is calculated based on the alcohol concentration A calculated in step 5101.

The required fuel flow rate of the fuel pump 14b, that is, the pump rotation speed Np is set and output to the fuel pumps 14a and 14b (Np
=chi (eight)). Then, the pump rotational speed Np of the fuel pumps 14a, 14b is held until the next fuel flow control program is executed.

As a result, the fuel pump 14. a, by 14b,
The fuel stored in the fuel tank 13 (alcohol only, gasoline only, or mixed fuel of alcohol and gasoline) is stored in the right bottom volume part 13c of the fuel tank 13.
, 13d, and each of the fuel pumps 14a, 14
The required maximum fuel flow rate is supplied to the fuel passage 19a by the required fuel flow corresponding to the alcohol concentration A discharged from the fuel passage 19a.

Then, the fuel pressure is controlled by the pressure regulator 16 to a constant differential pressure with the intake manifold internal pressure, and the fuel is injected from the injector 10 at a predetermined timing, and excess fuel passes through the fuel return passage 19b to the upper part of the fuel tank 13. The fuel is returned into the fuel tank 13 through the two facing ill outlets 19c, 19c.

Therefore, the above required maximum fuel flow rate is determined by the two fuel pumps 14.
．． Since it is controlled by a and 14b, the alcohol concentration can be changed from ○% to alcohol v! without using a special large fuel pump. The required maximum fuel flow rate, which changes depending on the alcohol concentration, can always be optimally ensured until the A degree reaches 100%. Therefore, fuel supply is always maintained in an optimal state, energy loss is avoided, and noise reduction is achieved.

Furthermore, by using two fuel pumps 14a, 14b, each fuel pump 14a, 14b can be made smaller;
This makes it easier to trap ants. Furthermore, since the fuel is sucked in from both the bottom volumes 13b and 13c, which are divided into the left and right sides of the fuel tank 13, no fuel remains in one of the volumes 13b and 13c, and the fuel can be used effectively until the end. I can do it.

Further, the discharge port 19 branched into two branches of the fuel return passage 19b
G and 19c face above the bottom volume portions 13b and 13C, so even if the fuel volume in the fuel tank 13 decreases, the bottom volume portions 13b and 13c
The fuel can be returned almost evenly to the bottom volume portion 13b or 13c, and the fuel can be prevented from shifting to one side of the bottom volume portion 13b or 13c, and air can be prevented from being sucked in from the fuel pump 14a1 or 14b.

Note that the present invention is not limited to the above-mentioned embodiment, and for example, three or more fuel pumps may be arranged in parallel.

[Effects of the Invention] As described above, according to the present invention, the alcohol CJ level brightening means for calculating the alcohol concentration of fuel based on the output signal of the alcohol concentration sensor;
Since the pump is equipped with pump flow rate setting means for setting the required fuel flow rate of a plurality of fuel pumps connected to the fuel tank based on the alcohol concentration calculated by the m degree calculation means, energy loss is reduced and noise is reduced. At the same time, it is possible to always obtain the optimal fuel amount corresponding to the alcohol concentration without using a large fuel pump and without causing a fuel shortage, and the capacity of each fuel pump can be made smaller. It has excellent effects such as easy installation.

[Brief explanation of drawings]

The drawings show an embodiment of the invention, and FIG. 1 shows the fuel flow f2i
iii. A functional block diagram of the IJ control device. Figure 2 is a schematic diagram of the engine control system. Figure 3 is an explanatory diagram showing the relationship between the required maximum fuel flow rate and the required fuel flow rate for the alcohol concentration. Figure 4 is It is a flowchart which shows a fuel flow+4i control procedure. 14a, 14b...Fuel pump, 15...Alcohol concentration sensor, 41...Alcohol depth detection means, 4
2...Pump flow rate setting means, A...Alcohol concentration.

Claims (1)

[Scope of Claims] Alcohol concentration calculation means for calculating the alcohol concentration of the fuel based on the output signal of the alcohol concentration sensor; and a plurality of fuels connected to the fuel tank based on the alcohol concentration calculated by the alcohol concentration calculation means. 1. A fuel flow rate control device for an alcohol engine, comprising pump flow rate setting means for setting a required fuel flow rate of the pump.