JPH0486365A - Fuel feed device for alcohol engine - Google Patents

Abstract

PURPOSE:To promptly uniform alcohol concentration by opening and closing an opening and closing valve for connecting the discharge side of a fuel pump to a fuel tank side on the basis of the change ratio per determined time of the alcohol concentration of a fuel and a necessary fuel flow rate to an engine side and driving the fuel pump. CONSTITUTION:In a fuel feed device for alcohol engine A, the discharge side of a fuel pump B is connected to an engine A side, and connected to a fuel tank D side through an opening and closing valve C. In the above constitution, the alcohol concentration of a fuel is calculated by an alcohol concentration calculating means M1. The change ratio per determined time of the calculated alcohol concentration is calculated by an alcohol concentration change ratio calculating means M2. Further, on the basis of the calculated alcohol concentration change ratio and a necessary fuel flow rate to the engine A side, the opening and closing valve C is opened and closed, and the pump B is driven, whereby the fuel feed quantity to the engine A side and the return flow rate to the fuel tank D side are controlled by a fuel flow rate control means M3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel supply device for an alcohol engine that makes the alcohol concentration of fuel uniform.

[Conventional technology] In recent years, due to worsening fuel conditions and demands for exhaust purification,
Systems that can use alcohol as a proxy fuel in addition to conventional gasoline are being put into practical use, such as:
Japanese Patent Laid-Open No. 61-65066 discloses that a fuel pump is provided in each of two passages leading to fuel with a low alcohol content and a fuel with a high alcohol content, and a switching valve is provided in the passage for fuel with a high alcohol content. By switching the switching valve, fuel with high alcohol content and fuel with low alcohol content are mixed and supplied to the engine during steady driving, and only fuel with low alcohol content is supplied to the engine during startup and acceleration. The technology has been disclosed.

In addition, systems have been developed that can run on not only gasoline, but also a mixture of alcohol and gasoline, and even alcohol alone.
icle (hereinafter referred to as TFFVJ), the alcohol concentration (content rate) of the fuel varies from 0% (gasoline only) to 1. It is possible to drive without any problem even if the fuel changes between 0% (alcohol only).

In general, alcohol fuel can basically be used without major changes to conventional gasoline engines by changing the air-fuel ratio, ignition timing, etc. However, since the stoichiometric air-fuel ratio is approximately half that of gasoline fuel, the above In Fri'V, the alcohol concentration of the fuel is usually detected by an alcohol concentration sensor installed in the fuel supply path to the engine, and the alcohol concentration is determined based on the output from this alcohol concentration sensor. The fuel injection amount, point, and ignition timing are optimized.

[Problems to be Solved by the Invention] However, for example, if only one of gasoline or alcohol is supplied during refueling, or if gasoline and alcohol are separated in the fuel tank at low temperatures, The alcohol concentration of the fuel in the fuel supply path changes drastically, and the fuel injection amount and ignition timing based on the alcohol concentration detected by the alcohol concentration sensor become inappropriate, resulting in deterioration of engine startability.

Furthermore, since there is a temporal and spatial lag between the installation position of the alcohol concentration sensor and the position where fuel is actually supplied to the engine from the injector, etc., A difference occurs between the alcohol concentration of the fuel and the alcohol concentration of the fuel actually supplied to the engine, resulting in poor controllability.

[Object of the Invention] The present invention has been made in view of the above circumstances, and even when the alcohol concentration distribution in the fuel tank is greatly different, the alcohol concentration of the fuel is quickly uniformized and supplied to the engine, and the controllability is improved. It is an object of the present invention to provide a fuel supply device for an alcohol engine that can improve the fuel consumption of an alcohol engine.

[Means for Solving the Problems] In order to achieve the above object, a fuel supply device for an alcohol engine according to the present invention connects the discharge side of a fuel pump to the engine side and also connects to the fuel tank side via an on-off valve. In a fuel supply system for an alcohol engine, as shown in FIG. The alcohol concentration change rate calculation means M2 calculates the alcohol concentration change rate, and the on-off valve is opened and closed based on the alcohol concentration change rate calculated by the alcohol concentration change rate calculation means M2 and the required fuel flow rate to the engine side, and the fuel pump is operated. The fuel flow rate control means M3 is driven to control the amount of fuel supplied to the engine side and the return flow rate to the fuel tank side.

1 Effect] In the alcohol engine fuel supply system having the above configuration, the alcohol concentration calculating means M1 calculates the fuel no.
The alcohol concentration is calculated, and the rate of change of this alcohol concentration per predetermined time is calculated by the alcohol concentration change rate calculation means M2.

Then, the fuel flow rate control means M3 opens and closes an on-off valve connected to the discharge side of the fuel pump and drives the fuel pump based on the alcohol concentration change rate and the required fuel flow rate to the engine side. The amount of fuel supplied from the pump to the engine side and the amount of fuel supplied from the fuel pump to the fuel tank fltl in accordance with the opening and closing of the on-off valve.
The flow rate of litter returning to I is controlled.

[Embodiments of the invention] Hereinafter, the present invention will be described in detail with reference to the drawings.

Figure 2 and the following diagrams show one embodiment of the present invention. Figure 2 is a schematic diagram of an engine control system, Figure 3 is a flowchart showing a fuel pump control procedure, and Figure 4 is an explanatory diagram showing a driving range of the fuel pump. , FIG. 5 is an explanatory diagram showing the switching area by the electromagnetic valve.

(Configuration of Engine Control System) In FIG. 2, the symbol ] is an engine for an FFV, and the figure shows a horizontally opposed four-cylinder engine. An intake manifold 3 is communicated with intake bows 1 to 22) formed in a cylinder bed 2 of the engine 1, and a throttle chamber 5 is communicated with the intake manifold 3 via an air chamber 4.

An air cleaner 7 is connected to the second stream side of the thrower 1 and the swing jumper 5-4 via an intake pipe 6, and an intake air amount sensor (not shown in the figure) is located directly downstream of the air cleaner 7 in the intake pipe 6.・Wire type air flow meter) 8 is installed.

Further, a throttle valve 5a is interposed in the slot chamber 5 of the slot 1, and a throttle opening sensor 9a and an idle switch 9b for detecting a fully open throttle valve are connected to the throttle valve 5a.

In addition, the combustion chamber 1 of each cylinder of the intake manifold 3
An injector 10 is disposed immediately upstream of each intake bow 1 to 2a communicating with the combustion chamber 1-a, and an ignition plug 1-1 is provided for each cylinder of the cylinder head 2, the tip of which is exposed to the combustion chamber 1-a. is being taken away.

Further, reference numeral 12 is a fuel tank, and this fuel tank 1
2 stores fuels with different alcohol concentrations A (%) depending on the user's refueling situation, such as alcohol only, a mixed fuel of alcohol and gasoline, or only gasoline.

The suction side of the first fuel pump 13 and the suction side of the second fuel pump 14 connected in parallel are connected to the fuel tank] 2, and the discharge side of the first fuel pump 13 is connected to the fuel supply path 15a. The discharge side of the second fuel pump 14 is connected to an on-off valve such as a solenoid valve 26.

The E solenoid valve 26 is a three-boat solenoid valve, in which the first boat is connected to the discharge side of the second fuel pump 1.4, and the second boat is connected to the discharge side of the second fuel pump 1.4.
The bows 1 to 1 communicate with the fuel supply passage 1.5a.

Further, the solenoid valve 26 is connected to the bypass passage 15b through which the third boat communicates with the fuel tank 12, and the first solenoid valve 26 is in a de-energized state. The boat and the second boats 1 to 1 communicate with each other, and the discharge side of the second fuel pump 14 is connected to the fuel supply path 1 to 5.
a, and in the energized state, the first. Boat and third ball
The discharge side of the second fuel pump 14 communicates with the bypass passage 151 and is cut off from the fuel supply passage 15a.

Note that the first and second fuel pumps 1.3.14 are driven by a DC motor.

The fuel supply path 15a is provided with a fuel filter 16, an alcohol concentration sensor 7, and an injector 10.
The injector 10 is connected to a pressure regulator 8, and the fuel regulated by the pressure regulator 8 is injected from the injector 10, and the return fuel is injected from the injector 10. The fuel is returned from the pressure regulator 8 to the fuel tank 12.

A crank rotor 19 is attached to the crankshaft 1b of the engine 1, and the crank rotor 19 has an electromagnetic pickup on the outer periphery that detects a protrusion (or slit 1-) corresponding to a predetermined crank angle. A sensor 20 is provided oppositely.

Further, a cooling water temperature sensor 21 faces a cooling water passage (not shown) forming a riser formed in the intake manifold 3, and an 02 sensor 23 is placed in an exhaust pipe 22 communicating with the exhaust boat 2b of the cylinder head 2. It is coming. In addition, the code|symbol 24 is a catalytic converter.

(Circuit of control device) On the other hand, reference numeral 30 is a control device (ECU) consisting of a microcomputer, etc., and the CI of this ECU3O) U3
1, ROM 32, R, AM 33, and I10 interface 34 are connected to each other via a pass line 35, and a predetermined stabilized voltage is supplied from a constant voltage circuit 36.

The ECU 3O includes an alcohol concentration calculation means for calculating the alcohol concentration of the fuel, an alcohol concentration change rate calculation means for calculating the rate of change per predetermined time of the alcohol concentration calculated by the alcohol concentration calculation means, and the alcohol] - Based on the alcohol concentration change rate calculated by the concentration change rate calculation means and the required fuel flow rate to the engine side, open and close the on-off valve and drive the fuel pump to increase the amount of fuel supplied to the engine side and the fuel pump. Fuel supply control functions such as fuel meteor control means for controlling the return flow rate to the tank side are realized, and other control functions such as fuel injection control and ignition timing control are also realized.

The constant voltage circuit 36 is connected to a battery 38 via a relay contact of an ECU relay 37.
7 relay coils are connected to the battery 38 via three ignition switches.

In addition, the input ports 1 to 1 of the I10 interface 34 are
For each of the above sensors 8, 9a, 1.7, 20°21.2
B and the idle switch 9b are connected, and the relay contact of the ECU relay 37 is connected to monitor the battery voltage, and the igniter 25 is connected to the output port of the interface 34 (10). At the same time, the injector 10 via the drive circuit 40,
1st. Second fuel pump 13, 1.4 and solenoid valve 26
is connected.

In addition, the ROM 32 stores a control program and fixed data for control, and also includes the following:
Stores the output signals of the sensors and switches after data processing and the data processed by the CPU 31.

According to the control program stored in the ROM 32, the CPU 3 calculates the alcohol concentration of the fuel in the fuel supply path 15a at predetermined time intervals based on the signal from the alcohol concentration sensor 17, and calculates the fuel injection amount according to the alcohol concentration. , ignition timing, etc., and outputs a drive pulse width signal for the injector 10, an ignition signal for the spark plug 11, etc.

Then, the CPU 31 sets the required fuel flow rate of the fuel supply system for the fuel injection amount, calculates the alcohol concentration change rate from the alcohol concentration value at each predetermined time, and turns on the solenoid valve 26.

At the same time as turning OFF, the first. The drive range of the second fuel pump 13]4 is switched.

(Operation) Next, the operation of the embodiment with the above configuration will be explained according to flowchart I in FIG.

The program not shown in flowchart 1 is an interrupt routine that is activated at predetermined time intervals.
In step 101, the alcohol concentration AN[Δ is calculated based on the signal from the alcohol concentration sensor 17, and in step 5102
The fuel injection amount Ti is not read from the RAM 33.

This fuel injection amount Ti is set in the main routine in the ECU 3O, and at the time of startup, it is set by a map search using the cooling water temperature TW and alcohol concentration A as parameters, and after complete combustion, the air-fuel ratio is determined based on the alcohol concentration A. Alcohol content correction coefficient KA1. , various increase correction coefficients CO related to cooling water temperature increase correction, acceleration/deceleration increase correction, etc., and correct the basic fuel injection amount Tp by the air-fuel ratio feedback correction coefficient α based on the output signal of the 02 sensor 23, It is set by adding the voltage correction pulse width TS that interpolates the invalid injection time to the power supply voltage of the injector 10 (Ti←'rp to XK8XCOEFX α+TS).

Next, proceed to step 5103 and proceed to ``binary step 510
Function f whose parameter is the fuel injection amount Ti read out in step 2.
Set the required fuel flow rate F of the fuel supply system by FL
4-f(Ti)), this required fuel flow @, F l- is compared in step 5104 with a set value F LSET.

When FL≧Fl-3ET in the above step 5104, the process proceeds from the above step 5104 to step 5105,
The state in which the electromagnetic valve 26 is de-energized and the second fuel pump 14 is connected to the injector 10 side, that is, the discharge side of the second fuel pump 14 is communicated with the injector 10 side via the fuel supply path 15a, and the process proceeds to step 5112. move on.

In step 5112, the first . Second fuel pump 1314
is driven at the same time to ensure the required fuel flow rate F1- set in step 8103 above, and the process proceeds to step 5113 where R
Previous alcohol concentration AOL stored in AM33
D is the alcohol concentration A NE calculated using this routine.
Update by W (AOLD 4-ANEW) L, exit the routine.

That is, as shown in FIG. 5, when the required fuel flow rate PL is large, the discharge side of the second fuel pump 14 is connected to the injector side, and as shown in FIG.
By simultaneously driving the second fuel pump 1314, the required fuel flow rate FL is ensured.

On the other hand, if T'l<FLS[T in step 5104, step 5104 to step 8106
Proceed to the previous routine's alcohol concentration A O
LD is read from the RAM 33, and in step 5107, this previous alcohol concentration A OLD and this time step 51
Calculate the alcohol concentration change rate dA/di per execution cycle time of this interrupt routine based on the alcohol concentration ANIEW newly calculated in step 01.
t +-d (ANEW-AOLD)/d t, )
, proceed to step 8108.

In step 5108, the absolute value of the rate of change in alcohol concentration dA/dt calculated in step 5107 and the set value S are determined.
ET, l d A / d t 1> SE
When T, the electromagnetic valve 26 is energized in step 5109 to connect the second fuel pump 14 to the fuel tank line 2 side, that is, the discharge side of the second fuel pump 14 is supplied with fuel via the bypass passage 151). The communication is made to the tank 12, and the process proceeds to step 5112 described above. They also drive the second fuel pumps 13,14.

That is, when the alcohol and gasoline in the fuel tank 12 are in a separated state at low temperatures, or
When the alcohol concentration A in the fuel tank 12 is low (high) and only alcohol (gasoline only) is refilled, the alcohol concentration A of the fuel in the fuel supply path 15a fluctuates greatly, and the alcohol concentration A changes over time. The color becomes darker or lighter.

Therefore, when the absolute value of the rate of change in alcohol concentration per predetermined time, 1 dA/dtl, exceeds the set value of 5 IET,
It can be determined that the alcohol concentration distribution of the fuel in the fuel tank 12 differs greatly depending on the location, and at this time, as shown in FIG. The second fuel pumps 13, 1.4 are simultaneously driven, and the discharge side of the second fuel pump 1-4 is connected to the fuel tank 2 side, as shown in FIG.

As a result, from the first fuel pump 13 to the injector 1-
While supplying the required fuel flow rate F to the 0 side, the fuel in the fuel tank 12 is rapidly circulated by the second fuel pump], /] via the bypass passage 15[), and the fuel in the fuel tank 2 is rapidly circulated through the bypass passage 15[). The alcohol concentration distribution can be immediately made uniform, and furthermore, the alcohol concentration A between the position of the injector which actually supplies fuel to the engine] 0 and the installation position of the alcohol concentration sensor 17 is Spatial deviation can be eliminated and controllability can be improved.

On the other hand, in binary step 5108 ldA/dtl≦SE
When T, it is determined that the alcohol concentration distribution of the fuel in the fuel tank 12 is approximately equal, and step 810 is performed.
8 to step 5110, the solenoid valve 26 is de-energized and the second fuel pump 14 is connected to the injector 10, and in step 5111 only the first fuel pump 13 is driven to return to the normal operating state. do.

Then, from step 5111 to step 5 described above,
The process advances to step 113, where the previous alcohol concentration AOLD stored in the RAM 33 is updated with the alcohol concentration A NEW calculated in the current routine (AOI-D←ANE), and the routine exits.

(Other Embodiments) FIG. 6 is a schematic diagram of an engine control system showing another embodiment of the present invention. In this embodiment, the second fuel pump 1
4, only a large-capacity first fuel pump 1-3 is used, and the discharge side of this first fuel pump 3 is connected to the fuel supply path 15a.
It is connected to the bypass passage 15b, and a throttle 27 and a solenoid valve 28 are interposed in the bypass passage 15b.

The solenoid valve 28 is a two-way valve that only opens and closes the bypass passage 15b, and when the solenoid valve 28 is de-energized and the discharge side of the first fuel pump 13 is cut off from the fuel oil tank 12 side. When the first fuel pump 13 alone supplies the required flow rate F1-, and the electromagnetic valve 28 is energized to connect the discharge side of the first fuel pump 13 to the fuel tank 12 side, the bypass passage], 5 b. The return flow rate that returns to the fuel tank 12 via the throttle 2
7, and the flow rate flowing to the injector]0 side is ensured.

In this embodiment, steps 5111 and 3112 of the program shown in FIG. Even if the alcohol concentration distribution varies greatly from place to place, the alcohol concentration distribution can be immediately made uniform.

Note that the present invention is not limited to the embodiments, and for example, the drive motors of the first fuel pump 13 and the second fuel pump 14 may be AC motors, and the pump rotation speed (pump discharge amount) may be varied by frequency control. Also good.

[Effects of the Invention] As explained above, according to the present invention, the discharge side of the fuel pump is moved to the fuel tank side based on the rate of change in the alcohol concentration of the fuel per predetermined time and the required fuel flow rate to the engine side. The fuel pump is driven as the connected on-off valve opens and closes, and the amount of fuel supplied from this fuel pump to the engine side and the amount of fuel returned from the fuel pump to the fuel tank side as the on-off valve opens and closes. The turn flow rate is controlled.

Therefore, even during a transient period when the alcohol concentration of the fuel changes, the return fuel to the fuel tank can promote fuel mixing and quickly equalize the alcohol concentration, and the fuel supply amount and ignition can be adjusted based on this alcohol concentration. By keeping the timing etc. optimal, excellent effects can be achieved, such as improving controllability, improving engine startability, and improving driving feeling.

[Brief explanation of drawings]

Fig. 1 shows the basic construction of the present invention, but does not show the crane/correspondence diagram, Figs. 2 to 5 show an embodiment of the present invention, Fig. 2 is a schematic diagram of the engine control system, and Fig. 3 Flowcharts 1 to 4 showing the fuel pump control procedure, FIG. 4 is an explanatory diagram showing the drive area of the fuel pump, FIG. 5 is an explanatory diagram showing the switching area by the electromagnetic valve, and FIG. 6 is another embodiment of the present invention. FIG. 2 is a schematic diagram of an engine control system. Ml...Alcohol concentration calculation means M2...Alcohol concentration change rate calculation means M3...Fuel flow rate control means-' Also known as Kutozennai-kai late memorial wall

Claims (1)

[Claims] Connecting the discharge side of the fuel pump to the engine side,
A fuel supply system for an alcohol engine connected to a fuel tank side via an on-off valve includes an alcohol concentration calculation means for calculating the alcohol concentration of the fuel, and a rate of change per predetermined time in the alcohol concentration calculated by the alcohol concentration calculation means. an alcohol concentration change rate calculation means, which opens and closes the on-off valve and drives the fuel pump based on the alcohol concentration change rate calculated by the alcohol concentration change rate calculation means and the required fuel flow rate to the engine side; A fuel supply device for an alcohol engine, comprising: a fuel flow rate control means for controlling the amount of fuel supplied to the engine side and the return flow rate to the fuel tank side.