JPH0443850A - Fuel supply device of alcohol engine - Google Patents

Abstract

PURPOSE:To enhance controllability of an alcohol engine by setting the respective drive regions of first and second fuel pumps according to the calculated rate of change of alcohol density and the required amount of fuel flow for an engine. CONSTITUTION:At the fuel supply device of an alcohol engine the alcohol density of fuel is calculated by an alcohol density calculating means Ml and the rate of change of the alcohol density per unit time is calculated by a calculating means M2 for the rate of change of the alcohol density. A fuel pump drive region setting means M3 sets the respective drive regions of first and second fuel pumps according to this rate of change of the alcohol density and the required amount of fuel flow for an engine, both of the pumps being connected in parallel to a fuel tank; and the first and second fuel tanks are selectively driven at their respective drive regions or driven simultaneously.

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 an alternative fuel in addition to conventional gasoline are being put into practical use; for example,
Japanese Patent Application 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 valve, fuel with a high alcohol content and fuel with a low alcohol content are mixed and supplied to the engine during steady driving, and only fuel with a 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.
cle, hereinafter referred to as rFFVJ), there is no problem even if the alcohol concentration (content rate) of the fuel changes between 0% (gasoline only) and 100% (alcohol only) depending on the user's circumstances when refueling. It is now possible to run.

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 FFV, usually
The alcohol concentration of the fuel is detected by an alcohol concentration sensor installed in the fuel supply path to the engine, and the optimal fuel injection amount and ignition timing are determined based on the output from the alcohol concentration sensor.

[Problem H to be solved by the invention] However, for example, when refueling only one of gasoline or alcohol is supplied, or when 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 location of the alcohol concentration sensor and the location where fuel is actually supplied to the engine from the injector, etc., the fuel detected by the alcohol concentration sensor A difference occurs between the alcohol concentration and the alcohol concentration of the fuel actually supplied to the engine, resulting in poor controllability.

[Purpose 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 a first fuel pump and a second fuel pump in parallel to a fuel tank, and supplies these fuels. In a fuel supply device for an alcohol engine, the fuel from the pump is pressure-regulated by a pressure regulator and supplied to the engine, and the return fuel from the pressure regulator is returned to the fuel tank to circulate the fuel,
As shown in FIG. 1, alcohol concentration calculation means M1 calculates the alcohol concentration of fuel, and alcohol concentration change rate calculation means M2 calculates the rate of change per predetermined time of the alcohol concentration calculated by the alcohol concentration calculation means M1.
and a fuel pump that sets a drive range for the first fuel pump and the second fuel pump based on the alcohol concentration change rate calculated by the alcohol concentration change rate calculation means M2 and the required fuel flow rate for the engine. The driving area setting means M3 is also provided.

[Operation] In the alcohol engine fuel supply device according to the above-mentioned ellipse configuration, the alcohol concentration of the fuel is calculated by the alcohol concentration calculation means M1, and the rate of change of this alcohol concentration per predetermined time is calculated by the alcohol concentration change rate calculation means M2. be done.

Based on this alcohol concentration change rate and the required fuel flow 1 for the engine, the drive range of the first fuel pump and the second fuel pump connected in parallel to the fuel tank is determined by the fuel pump drive range setting means M3. In each drive region, the first fuel pump and the second fuel pump are switched and driven, or the first fuel pump and the second fuel pump are driven simultaneously. .

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

2 and 3 show a first embodiment of the present invention, FIG. 2 is a schematic diagram of an engine control system, and FIG. 3 is a flowchart showing a fuel pump control procedure.

(Configuration of engine control system) In Fig. 2, reference numeral 1 is an alcohol engine for FFV, and the figure shows a horizontally opposed four-cylinder engine. A manifold 3 is communicated with the intake manifold 3, and a throttle chamber 5 is communicated with the intake manifold 3 via an air chamber 4.

An air cleaner 7 is attached to the upstream side of the throttle chamber 5 via an intake pipe 6, and an intake air amount sensor (a hot wire air flow meter in the figure) 8 is installed directly downstream of the air cleaner 7 in the intake pipe 6. equipped.

Also, a throttle valve 5 is provided in the throttle chamber 5.
A is inserted into the throttle valve 5a, and a throttle opening sensor 9a and an idle switch 9b for detecting fully closed 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 boat 2a communicating with the combustion chamber 1a, and a spark plug 11 is attached to each cylinder of the cylinder head 2, the tip of which is exposed to the combustion chamber 1a. .

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 fuel tank 12 is connected to the suction side of the first fuel pump 13 and the suction side of the second fuel pump 14, which are connected in parallel. Second fuel pump 13.1
The respective discharge sides of 4 are joined together and communicated with a fuel supply path 15.

In addition, the above 1. The second fuel pumps 13, 14 are driven by DC motors.

The fuel supply path 15 is connected to the injector 10 through which a fuel filter 16 and an alcohol concentration sensor 17 are interposed.Furthermore, the injector 10 is connected to a pressure regulator 18, and the pressure is regulated by the pressure regulator 18. The returned fuel is injected from the injector 10, and the return fuel is returned to the fuel tank 12 from the pressure regulator 18.

The first fuel pump 13 has a capacity that alone can cover the required fuel flow for the amount of fuel required by the engine when the alcohol concentration A of the fuel is 100% (alcohol only). 14 is driven together with the first fuel pump 13, and is set to have a capacity that allows the fuel in the fuel tank 12 to be rapidly agitated by the return fuel from the pressure regulator 18.

Further, a crank rotor 19 is attached to the crankshaft 1b of the engine 1, and a crank angle sensor 20 is provided on the outer periphery of the crank rotor 19, such as an electromagnetic pickup that detects a protrusion (or slit) corresponding to a predetermined crank angle. are set up opposite each other.

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 configuration of control device) On the other hand, reference numeral 30 is a control device (ECU) consisting of a microcomputer, etc., and the CPU of this ECtJ30:
31- ROM32, RAM33. The I10 interfaces 34 are connected to each other via a pass line 35, and a predetermined stabilized voltage is supplied from a constant voltage circuit 136.

and an alcohol concentration calculation means that calculates the alcohol concentration of the fuel according to 1 ECtJ30, an alcohol concentration rental rate calculation means that calculates the rate of change per predetermined time of the alcohol concentration calculated by the alcohol concentration calculation means;
and fuel pump drive range setting for setting drive ranges for the first fuel pump and the second fuel pump based on the alcohol concentration change rate calculated by the alcohol concentration change rate calculation means and the required fuel flow rate for the engine. Fuel supply control functions such as means are realized, and other control functions such as fuel injection control, ignition timing control, etc. are 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.

Further, the input ports of the I10 interface 34 include the sensors 8, 9a, 17, 20°21, 23.
The idle switch 9b is connected, and the relay contact of the ECU relay 37 is connected to monitor the battery voltage, and the I10 interface 3 is connected.
An igniter 25 is connected to the output boat No. 4, and the injector 10 and the first output boat are connected via a drive circuit 40.
A second fuel pump 13.14 is connected.

Further, the ROM 32 stores control programs and fixed data for control, and the RAM 3B stores output signals of the sensors and switches after data processing and data processed by the CPU 31. Stored.

The CPU 31 calculates the alcohol concentration of the fuel in the fuel supply path 15 at predetermined time intervals based on the signal from the alcohol concentration sensor 17 according to the control program stored in the ROM 32, and controls the fuel injection control according to the alcohol concentration. It calculates the spark timing, etc., and outputs a drive pulse width signal for the injector 10, an ignition signal for the spark plug 1, etc.

Further, the CPU 31 calculates the rate of change in alcohol concentration from the value of alcohol concentration at each predetermined time, and compares this rate of change in alcohol concentration with a preset value l-. The driving range of the second fuel pumps 13 and 14 is set.

(Operation) Next, the operation of the embodiment with the above configuration will be explained according to the flowchart of FIG. 3.

The program shown in this flowchart is an interrupt routine that is activated at predetermined time intervals.
At step 01, the alcohol concentration A NEW is calculated based on the signal from the alcohol concentration sensor 17, and the alcohol concentration A OLD from the previous routine is stored in the RAM 3.
Read from 3.

Next, the process proceeds to step 5102, where the alcohol concentration change rate dA/d per execution cycle time of this interrupt routine is determined from the alcohol concentration AOLD in the previous routine and the alcohol concentration AXE- newly calculated this time.
Calculate t: dA/dt 4-ci<AIIE corpse-AO
LD)/d t ), the process proceeds to step 5103.

In step 5103, the absolute value of the rate of change in alcohol concentration dA/dt calculated in step 5102 and the set value S are determined.
ET, and when l dA/d t I > SET, the process advances to step 51011 and the first. They also drive the second fuel pumps 13,14.

That is, when the alcohol and gasoline in the fuel tank 12 are separated at low temperatures, or
When the alcohol concentration A of 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 15
The alcohol content fluctuates widely, with the alcohol content becoming thicker or thinner over time.

Therefore, when the absolute value 1 dA/dtl of the rate of change in alcohol concentration per predetermined time exceeds the set value SET, it can be determined that the alcohol concentration distribution of the fuel in the fuel tank 12 differs greatly depending on the location. 1. The second fuel pumps 13 and 14 are driven at the same time to increase the amount of fuel pumped from the pumps compared to the amount of fuel pumped under normal operating conditions, thereby maximizing the amount of fuel returned from the pressure regulator 18 and increasing the amount of fuel pumped in the fuel tank 12. By rapidly circulating the fuel, the alcohol concentration distribution of the fuel in the fuel tank 12 can be immediately made uniform.

In addition, this also allows for a temporal change in alcohol concentration A between the position of the injector lO that actually supplies fuel to the engine and the installation position of the alcohol concentration sensor 17.
Spatial deviations can be eliminated and controllability can be improved.

On the other hand, in step 5103 above, l dA/dt l≦S
At the time of ET, it is determined that the alcohol concentration distribution of the fuel in the fuel tank 12 is approximately equal, and step 51 is performed.
03 to step 5105, the first fuel pump 13
drive only to bring it into normal operating condition.

Then, step 5104 or step 510
5 to step 8106, where the previous alcohol concentration AOLD stored in the RAM 33 is updated with the alcohol concentration ANE- calculated in the current routine (AO
LD-ANElI) and exit the routine.

(Second Embodiment) FIGS. 4 and 5 show a second embodiment of the present invention. FIG. 4 is a flowchart showing a fuel pump control procedure, and FIG. 5 is an explanatory diagram showing a driving range of the fuel pump. be.

The second embodiment aims to reduce power consumption by driving the pump, and is different from the first embodiment described above by using the first fuel cylinder 1.
13, the capacity of the second fuel pump 14 is increased accordingly, and the capacity of the second fuel pump 14 is increased accordingly. By simultaneously driving the second fuel pumps 13 and 14, the necessary maximum fuel flow rate can be ensured when the fuel is only alcohol, and the fuel in the fuel tank 12 can be rapidly stirred by the return fuel from the pressure regulator 18. This is to ensure the flow rate.

In the interrupt routine of the fuel pump control procedure every predetermined time shown in FIG. AXE- and set alcohol concentration A S
Compare with ET.

In the above step 5202, when ANEW > ASET, that is, when the alcohol concentration AWE- is high and the required fuel flow rate is large, the process proceeds from the above step 5202 to step 5207, where both the first and second fuel pumps 13 and 14 are set to the driving state. Exit the routine, AXE-≦A
When SET, the process proceeds from step 5202 to step 5203, where the alcohol concentration A 01D in the previous routine is read out from the RAM 33, and step 520
4, the alcohol concentration AOL in the previous routine
From D and the newly calculated alcohol concentration A NEW, calculate the alcohol concentration change rate dA/dt per execution cycle time of this interrupt routine (dA/d
t-d (ANEW-AOLD)/dt).

Next, proceed to step 5205, and proceed to step 5204 described above.
The absolute value of the rate of change in alcohol concentration dA/dt calculated in dA/dt is compared with the set value SET, and when ldA/dt is SET, the process branches to step 5207 described above and both the first and second fuel pumps 13 and 14 are connected. Drive state, dA/dtl≦
At the time of SET, it is determined that the alcohol concentration distribution of the fuel in the fuel tank 12 is approximately equal, and step 5 is performed.
Proceeding from step 205 to step 3206, the first fuel pump 1
3 to reduce power consumption.

Then, step 8206 or step 520
Proceeding from step 7 to step 8208, the previous alcohol concentration A OLD stored in RAM 3B is updated with the alcohol concentration A NEW (A
OLD-ANEW) and exit the routine.

That is, as shown in FIG. 5, when the alcohol concentration A of the fuel is low and the alcohol concentration change rate dA/dtl (absolute value) is small, only the first fuel pump 13 is driven to ensure the required maximum fuel flow rate. At the same time, when the alcohol concentration A of the fuel is high or when the alcohol concentration change rate 1 dA/dt l (absolute value) is large, the first. The second fuel pumps 13, 14 are driven simultaneously to ensure the required maximum fuel flow rate and to rapidly circulate the fuel in the fuel tank 12.

(Third Embodiment) Fig. 6 and Fig. 7 show a third embodiment of the present invention, Fig. 6 is a flowchart showing the fuel pump 1 control procedure, and Fig. 7 is an explanatory diagram showing the driving range of the fuel pump. It is.

This third embodiment aims to further reduce power consumption than the above-mentioned second embodiment, and in the interrupt routine shown in FIG. 6 at predetermined time intervals, the alcohol concentration ANE- is calculated in step 5301, In step 5302, a basic fuel injection amount Tp is set based on the engine speed N and the intake air amount Q (Tp←KxQ/N; K is a constant).

Next, the process proceeds to step 5303, where the feedback correction coefficient α is based on the output voltage from the 02 sensor 23, and various increase correction coefficients are based on the output signals from the cooling water temperature sensor 21, throttle opening sensor 9a, idle switch 9b, etc. Based on C0FF and the alcohol division positive coefficient KAL based on the signal from the alcohol concentration sensor 17, the basic fuel injection amount Tp set in step 5302 is determined.
At the same time, the voltage correction pulse width TS for interpolating the invalid injection time of the injector 10 is added to set the final fuel injection amount Ti, and the process proceeds to step 5304.

In step 5304, based on the fuel injection amount Ti set in step 5303, the required fuel flow rate F[F L −f (Ti)) for the engine is calculated from a function f(Ti) using this fuel injection 31r* as a parameter.
, and is compared with a set value F LSET (capacity of the first fuel pump 13) in step 5305.

Note that the required fuel flow rate PL may be set by map search using the fuel injection amount Ti as a parameter.

In step 5305 above, when FL>FLSET,
Proceed to step 5310 and proceed to the first step. The second fuel pumps 13 and 14 are simultaneously driven, and when F[≦F LSET,
Proceeding from step 5305 to step 3306, the alcohol concentration AOLD in the previous routine is RA
M33 is read, and in step 5307, the alcohol concentration change rate d per execution cycle time of this interrupt routine is calculated from the alcohol concentration AOLD in the previous routine and the alcohol concentration ANEW newly calculated this time.
Calculate A/dt (dA/dt←d (ANEW −
AOLD)/d t').

Then, the process proceeds from step 5307 to step 8308, where the absolute value of this rate of change in alcohol concentration dA/dt is compared with the set value SET, and l dA/dt l > SET
In this case, the process branches to step 5310 described above. Second
Both the fuel pumps 13 and 14 are activated in step 53.
On the other hand, when ldA/dtl≦SET, the process proceeds from step 3308 to step 5309, where only the first fuel pump 13 is driven, and the process proceeds to step 53.
11/\Proceed.

Then, in step 5311, the previous alcohol concentration AOLD stored in the RAM 33 is updated (AO
LD=ANEW) I, exit the routine.

That is, in this third embodiment, as shown in FIG. 7, the required fuel flow rate F[ for the engine is determined based on the fuel injection amount Ti, and the first. Since the drive range of the second fuel pump 1314 is set, the drive range of the second fuel pump 1314 is set depending on the engine operating state. The drive of the second fuel pumps 13, 14 is switched, and power consumption can be further reduced compared to the second embodiment.

(Fourth Embodiment) Figures 8 to 10 show a fourth embodiment of the present invention, in which Figure 8 is a schematic diagram of the engine control system, Figure 9 is a flowchart showing the fuel pump control procedure, and Figure 10 is a flowchart showing the fuel pump control procedure. FIG. 2 is an explanatory diagram showing a driving region of a fuel bonder.

In the fourth embodiment, the configuration of the ECU 3O is slightly different from the first embodiment described above, and as shown in FIG. Connect the 1st and 2nd fuel pumps 13.
The pump output amount is varied by controlling the drive voltage of 14.

That is, in the interrupt routine shown in FIG. 9 at predetermined time intervals, the alcohol concentration sensor 17 is
The alcohol concentration ANE- is calculated based on the signal from the previous routine.
Read OLD from RAM3B.

Next, the process proceeds to step 5402, where the alcohol concentration change rate dA/d per execution cycle time of this interrupt routine is determined from the alcohol concentration AOLD in the previous routine and the alcohol concentration AXE- newly calculated this time.
Calculate t: dA/dt←d(ANEW -AOLD)
/d t ), the process proceeds to step 5403.

In step 5403, the absolute value of the rate of change in alcohol concentration dA/dt calculated in step 5402 and the set value S are determined.
ET, and when ldA/dtl≦SET, the process advances to step 5404 and the engine speed N and intake air amount Q are compared.
Set the basic fuel injection amount Tp based on Tp4-K.
XQ/N; K is a constant), the process advances to step 5405.

Proceeding to step 5405, a feedback correction coefficient α based on the output voltage from the 02 sensor 23 and various increase correction coefficients COF F based on output signals from the cooling water temperature sensor 21, throttle opening sensor 9a, idle switch 9b, etc. and the alcohol content correction coefficient KAL based on the signal from the alcohol concentration sensor 17,
Basic fuel injection amount TI set in step 5404 above)
In step 84
Proceed to 06.

In step 8406, based on the fuel injection amount Ti set in step 5405, the required fuel flow rate FL is calculated from a function f (Ti) with this fuel injection amount T as a parameter. Fuel flow rate FL and set value F that is the maximum discharge amount of the first fuel pump 13
LSET is compared in step 5407.

Note that the required fuel flow rate F[ is a value obtained by adding a predetermined value as a margin to the amount of fuel required by the engine.

In the above step 5407, when FL≦F LSET, the process proceeds to step 8408 and sets the first fuel pump drive voltage E1 based on the required fuel flow rate FL calculated in the above step 3406 (El←f(FL)). When only the first fuel pump 13 is driven and FL>FLSET, the process proceeds from step 5407 to step 5409, and the first fuel pump drive voltage E1 is set so that the first fuel pump 13 has the maximum discharge amount (El -f(FLSET
)), the second fuel pump driving voltage E2 is set to supply the insufficient fuel flow rate (F L -FLSET) for the above required fuel flow rate F[E2←f(FLSET).
-FLSET)), the first fuel pump 13 and the second fuel pump 14 are driven simultaneously.

On the other hand, in step 5403 above, l dA/dt l>
At the time of SET, the process proceeds from step 5403 to step 5410, and the first fuel pump drive voltage E1 is set so that the first fuel pump 13 reaches the maximum discharge i (E
1-f (FLSET2)), the second fuel pump drive voltage E2 should be set so that the second fuel pump 14 has the maximum discharge amount (E2-f (FLSET2)).
, the fuel flow rate from the first and second fuel pumps 13, 14 is maximized to rapidly circulate the fuel in the fuel tank 12 to equalize the alcohol concentration A of the fuel.

That is, as shown in FIG. 10, when the alcohol concentration change rate (absolute value) is small, the first.
The pump discharge amount is varied by setting the second fuel pump drive voltages E1 and E2, and when the alcohol concentration change rate (absolute value) is large, the first fuel pump drive voltage E1 and E2 are set. The first fuel pump 13,14 has a maximum discharge i. Second fuel pump drive voltage El, E
2, it is possible to prevent waste of power when driving the pump and minimize power consumption.

Then, when the process proceeds from step 5408, 5409, 5410 to step 5411, the previous alcohol concentration AOLD stored in the RAM 33 is updated by the alcohol concentration AXE- calculated in the current routine (AOL
D4-ANEW) and exit the routine.

It should be noted that the present invention is not limited to the embodiments, but includes, for example, the first embodiment. The drive motor of the second fuel pump 13.14 is an AC motor, and the pump rotation speed (pump discharge J
t) may be varied.

[Effects of the Invention] As explained above, according to the present invention, based on the rate of change in the alcohol concentration of the fuel per predetermined time and the required fuel flow rate of the fuel supply system, the first In order to optimally set the driving range between the fuel pump and the second fuel pump, even if the alcohol concentration distribution in the fuel tank is greatly different, the fuel in the fuel tank can be rapidly pumped by the return fuel from the pressure regulator to the fuel tank. The alcohol concentration of the fuel can be quickly uniformized and supplied to the engine.

Therefore, it is possible to promote fuel mixing during transient changes in the alcohol concentration of the fuel, to equalize the alcohol concentration, and to maintain optimal fuel supply amount, ignition timing, etc. based on this alcohol concentration, improving controllability and engine starting. It has excellent effects such as improving performance and driving feeling.

[Brief explanation of drawings]

Figure 1 is a claim correspondence diagram showing the basic configuration of the present invention, Figure 2 is a claim correspondence diagram showing the basic configuration of the present invention.
3 shows a first embodiment of the present invention, FIG. 2 is a schematic diagram of an engine control system, FIG. 3 is a flowchart showing a fuel pump control procedure, and FIGS. Second
Embodiment 4 is a flowchart showing a fuel pump control procedure, FIG. 5 is an explanatory diagram showing a driving range of the fuel pump, and FIGS. 6 and 7 show a third embodiment of the present invention. Figure 6 is a flowchart showing the fuel pump control procedure;
The figures are explanatory diagrams showing the driving range of the fuel pump, Figures 8 to 1.
Fig. 0 shows a fourth embodiment of the present invention, Fig. 8 is a schematic diagram of engine startability, Fig. 9 is a flowchart showing the fuel pump control procedure, and Fig. 10 is an explanatory diagram showing the driving range of the fuel pump. be. Ml...Alcohol concentration calculation means M2...Alcohol concentration change rate calculation means M3...Fuel pump drive area setting means Fig. 3 Fig. 4 Fig. 5 PL = f mountain) \ Fig. 6 dA/dt ≦ When SET

Claims (1)

[Scope of Claims] A first fuel pump and a second fuel pump are connected in parallel to a fuel tank, and the pressure of fuel from these fuel pumps is regulated by a pressure regulator and supplied to the engine, and the pressure regulator In a fuel supply device for an alcohol engine that returns fuel from a fuel tank to a fuel tank and circulates the fuel, the alcohol concentration calculation means calculates the alcohol concentration of the fuel, and the alcohol concentration calculation means calculates the alcohol concentration calculated by the alcohol concentration calculation means per predetermined time. alcohol concentration change rate calculation means for calculating the rate of change; and alcohol concentration change rate calculation means for calculating the alcohol concentration change rate calculation means, based on the alcohol concentration change rate calculated by the alcohol concentration change rate calculation means and the required fuel flow rate for the engine, the first fuel pump and the second fuel 1. A fuel supply device for an alcohol engine, comprising fuel pump drive range setting means for setting a drive range for a pump.