JPH05149223A - Start control method of ffv engine and device thereof - Google Patents

Abstract

PURPOSE:To improve startability by heating fuel according to alcohol concentra tion effectively, and supplying it to an engine without installing a heating means such as a heater to an inlet passage of the engine. CONSTITUTION:If starting possibility judging temperature where alcohol concentration is set to be served as a parameter is compared with coolant temperature, and it is judged that it is impossible to start the engine, a heater relay is turned ON to start current supply to a PTC heater 34, the first change-over solenoid valve 32 and the second change-over solenoid valve 38 are energized to shut down a main fuel tank 26 and a sub-fuel tank 28 and switch the section behind a pressure regulator 29 to the second fuel return passage 40 side. A fuel heating completion judging value COUNT SET is set according to coolant temperature TW. In the case of a counted value COUNT > COUNT SET, the second fuel pump relay is turned ON to operate the second fuel pump, and heated fuel in a sub-fuel tank is pressure-fed to circulate fuel. It is thus possible to crank the engine and inject the heated fuel from an injector.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a start control method and a start control device for an FFV engine, which heats fuel supplied to the engine to improve startability.

[0002]

2. Description of the Related Art In recent years, due to deterioration of fuel conditions and demand for exhaust gas cleaning, a system that can simultaneously use alcohol as an alternative fuel in addition to conventional gasoline has been put into practical use. In such a vehicle (Flexible Fuel Vehicle, hereinafter referred to as “FFV”), it is possible to drive not only with gasoline but also with a mixed fuel of alcohol and gasoline, or only with alcohol. The alcohol concentration (content rate) of the fuel used varies from 0% (gasoline only) to 100% (alcohol only) depending on the user's circumstances when refueling.

In general, alcohol fuel is less likely to be vaporized at a low temperature and has a large latent heat of vaporization, as compared with gasoline fuel.
It has characteristics such as a high flash point, and when the alcohol concentration changes, the latent heat of vaporization, specific heat, startable temperature, stoichiometric air-fuel ratio, etc. will change and the starting conditions will change, especially at low temperatures. Therefore, there arises a problem that the startability is deteriorated.

In order to deal with this, there has been conventionally known a technique of promoting vaporization of fuel by a heating means such as a heater and a heating element to improve startability at a low temperature. For example, Japanese Utility Model Laid-Open No. 58-12669. The publication discloses an alcohol engine starting device for guiding a part of fuel to an alcohol reforming catalyst heated by a heater and supplying the reformed gas to a combustion chamber when the engine is cold.

Further, the applicant of the present invention has previously disclosed in Japanese Patent Laid-Open No. 3-70.
In Japanese Patent Publication No. 852, it is determined whether or not the engine can be started based on the alcohol concentration of the fuel and the engine temperature. When it is determined that the engine cannot be started, the required heat generation amount of the heating means is determined based on the alcohol concentration and the engine temperature. It proposes a technology that calculates appropriately and promotes vaporization of fuel without wasting energy to improve startability.

[0006]

However, in order to promote the vaporization of the fuel, heating means such as a heater must be provided in the intake passage of the engine, and the vaporization efficiency of the fuel, the heater efficiency, etc. must be taken into consideration. Then, it cannot be said that it is necessarily effective in improving startability.

Further, when the alcohol concentration of the fuel is low, no heating means such as a heater is required, which causes an increase in intake resistance.

The present invention has been made in view of the above circumstances, and is an FFV capable of improving the startability by efficiently heating the fuel according to the alcohol concentration and supplying the fuel to the engine.
An object of the present invention is to provide a starting control method and a starting control device for a commercial engine.

[0009]

FFV according to the first invention
A method for controlling the start-up of an engine for a vehicle is based on the alcohol concentration of the fuel and the engine temperature, a procedure for determining whether the engine can be started without heating the fuel, and a procedure for determining whether the engine can be started. When it is determined that it cannot be started with
The first fuel source and return destination is the main fuel tank
From the fuel circulation system to the second fuel circulation system, which is the fuel delivery source and the return destination of the sub fuel tank connected to the main fuel tank, and the procedure of determining whether or not the engine can be started. When it is determined that the sub-fuel tank cannot be started, a procedure for heating the fuel in the sub-fuel tank by a heating means, and a procedure for setting a discrimination value for determining whether or not the heating of the fuel in the sub-fuel tank is completed , A procedure for determining whether or not the heating of the fuel in the sub-fuel tank by the heating means is completed based on the determination value set in the procedure for setting the determination value, and whether or not the heating of the fuel is completed. When it is determined that the heating is completed in the procedure for determining whether or not it is determined, the procedure for supplying the fuel from the second fuel circulation system to the engine is provided.

In the FFV engine start control method according to the second aspect of the invention, in the first aspect of the invention, the discriminant value in the procedure for setting the discriminant value is set as the heating time of the heating means based on the cooling water temperature. It is characterized by

In the FFV engine starting control method according to the third invention, in the first invention, the discriminant value in the procedure for setting the discriminant value is set as a fuel temperature based on the alcohol concentration of the fuel and the cooling water temperature. It is characterized by setting.

A FFV engine start control method according to a fourth aspect of the present invention is the first aspect of the present invention, wherein the heating means in the heating procedure is an electric heater, and the discriminant value in the procedure for setting the discriminant value is the electric heater. Is set as a predetermined current consumption value.

In a FFV engine starting control method according to a fifth aspect of the invention, in the switching procedure of the first aspect of the invention, the main fuel tank is shut off from the sub fuel tank, and a fuel return passage is provided on the main fuel tank side. Is switched to the sub fuel tank side, the first fuel supply system is switched to the second fuel supply system.

According to a sixth aspect of the present invention, there is provided an FFV engine starting control device, wherein a first fuel circulation system having a main fuel tank as a fuel source and a fuel return destination, and a sub fuel tank connected to the main fuel tank are used as fuel sources. A switching means capable of selectively switching between a delivery source and a second fuel circulation system as a return destination, and a part of the fuel circulated by the first fuel circulation system or the second fuel circulation system in the engine. And a heating means for heating the fuel in the sub fuel tank.

According to a seventh aspect of the present invention, there is provided an FFV engine starting control device, wherein the switching means of the sixth aspect is provided with a first switching valve provided between the main fuel tank and the sub fuel tank, and a fuel return valve. It is characterized in that it is composed of a second switching valve provided in the passage.

In the FFV engine start control device according to the eighth aspect of the present invention, the fuel supply means according to the sixth aspect of the invention is configured such that a part of the fuel in the fuel pipe is introduced from the side of the main body facing the fuel pipe. It is characterized by being configured by a side flow type injector that takes in and injects.

A FFV engine start control device according to a ninth aspect of the invention is characterized in that the heating means of the sixth aspect is an electric heater for directly heating the fuel in the sub fuel tank.

[0018]

In the FFV engine start control method according to the first aspect of the present invention, it is determined whether or not the engine can be started without heating the fuel, based on the alcohol concentration of the fuel and the engine temperature. When it is determined that it is impossible, the first fuel circulation system is switched to the second fuel circulation system and the fuel in the sub fuel tank is heated by the heating means. Then, a determination value for determining completion of heating is set, and if it is determined that heating of the fuel in the sub fuel tank is completed based on this determination value, fuel is supplied from the second fuel circulation system to the engine.

In the FFV engine starting control method according to the second invention, in the first invention, the heating time of the heating means based on the cooling water temperature is set as a determination value, and completion of heating of the fuel in the sub fuel tank is set. Determine.

In the FFV engine starting control method according to the third invention, in the first invention, the fuel temperature based on the alcohol concentration of the fuel and the cooling water temperature is set as the determination value, and the fuel in the sub fuel tank is controlled. Determine the completion of heating.

In the FFV engine starting control method according to the fourth aspect of the present invention, in the first aspect of the present invention, the heating means is an electric heater, and a predetermined current consumption value of the electric heater is set as a discriminant value, and the sub-fuel tank inside The completion of heating the fuel is determined.

In the FFV engine start control method according to the fifth aspect of the present invention, in the first aspect of the present invention, the main fuel tank is shut off from the sub fuel tank, and a fuel return passage is provided from the main fuel tank side to the sub fuel tank. The fuel in the sub fuel tank heated to the second
Is supplied to the engine from the fuel circulation system.

In the FFV engine start control device according to the sixth aspect of the present invention, the fuel in the sub fuel tank is heated, and the main fuel tank is used as a fuel delivery source and a return destination from the first fuel circulation system to the sub fuel tank. It is possible to supply the heated fuel to the engine by switching to the second fuel circulation system, which serves as a fuel delivery source and a return destination.

In the FFV engine starting control device according to the seventh invention, in the sixth invention, the first switching valve provided between the main fuel tank and the sub fuel tank,
With the second switching valve provided in the fuel return passage, the first
And the second fuel circulation system is selectively switched.

In the FFV engine start control device according to the eighth aspect of the invention, in the sixth aspect of the invention, a part of the fuel in the fuel pipe is injected into the engine by the side flow type injector.

In the FFV engine start control device according to the ninth aspect, in the sixth aspect, the electric heater directly heats the fuel in the sub fuel tank.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 11 relate to a first embodiment of the present invention. FIG. 1 is a flowchart 1 showing a starting control procedure, FIG. 2 is a flowchart 2 showing a starting control procedure, and FIG. 3 is a starting control procedure. 3 and 4 of the flowchart shown are a flowchart of a timer routine, FIG. 5 is a flowchart showing a control procedure of a starter motor, FIG. 6 is a flowchart showing a fuel injection control procedure, FIG. 7 is a schematic diagram of an engine control system,
8 is a circuit configuration diagram of an engine control system, FIG. 9 is a cross-sectional view of a side flow type injector, FIG. 10 is an explanatory diagram showing a startable region and a non-startable region, and FIG. 11 is an explanatory diagram of a startable determination water temperature map. is there.

(Structure of engine control system) In FIG.
Reference numeral 1 is an FFV engine (a horizontally opposed four-cylinder engine in the figure), and a cylinder head 2 of the engine 1 has an intake port 2a and an exhaust port 2b. An intake manifold 3 is connected to the intake port 2a, and a throttle passage 5 is connected to an upstream side of the intake manifold 3 via an air chamber 4.
An air cleaner 7 is attached to the upstream side of the throttle passage 5 via an intake pipe 6, and the air cleaner 7 is in communication with an air intake chamber 8 which is an intake port for intake air.

On the other hand, an exhaust pipe 10 is connected to the exhaust port 2b via an exhaust manifold 9, and a catalytic converter 11 is inserted in the exhaust pipe 10 and connected to a muffler 12. A throttle valve 5a is provided in the throttle passage 5, and an intercooler 13 is provided in the intake pipe 6 immediately upstream of the throttle passage 5,
Further, a resonator chamber 14 is provided downstream of the air cleaner 7 in the intake pipe 6.

Further, an idle speed control valve (IS) is provided in a bypass passage 15 which connects the resonator chamber 14 and the intake manifold 3 and bypasses the upstream side and the downstream side of the throttle valve 5a.
CV) 16 is interposed. Furthermore, this ISCV1
A check valve 17 which is opened immediately downstream of the intake valve 6 when the intake pressure is negative is closed while the intake valve is supercharged by a turbocharger 18 to be described later and closed when the intake pressure becomes positive.

Further, reference numeral 18 is a turbocharger, and the turbine wheel 18 of this turbocharger 18 is shown.
a is a turbine housing 18 in which the exhaust pipe 10 is interposed.
A compressor housing 18e, which is housed in b, and has a compressor wheel 18d, which is connected to the turbine wheel 18a via a turbine shaft 18c, on the downstream side of the resonator chamber 14 of the intake pipe 6.
It is stored in.

A wastegate valve 19 is provided at the inlet of the turbine housing 18b, and a wastegate valve actuating actuator 20 is connected to the wastegate valve 19. This wastegate valve actuating actuator 20 is partitioned into two chambers by a diaphragm, one of which forms a pressure chamber communicating with the wastegate valve controlling duty solenoid valve 21, and the other of which forms the wastegate valve 19 in the closing direction. It forms a spring chamber that houses the spring that biases it.

The waste solenoid valve controlling duty solenoid valve 21 includes the resonator chamber 1
4 and the intake manifold 3 are provided in a passage communicating with each other, and the pressure on the side of the resonator chamber 14 and the intake manifold are determined according to the duty ratio of a control signal output from a control unit (ECU) 51 described later. The pressure on the side 3 is regulated and supplied to the pressure chamber of the waste gate valve actuating actuator 20, and the exhaust gas relief by the waste gate valve 19 is controlled to control the supercharging pressure by the turbocharger 18. Is becoming

An absolute pressure sensor 22 is attached to the intake manifold 3, and an injector 23 as a fuel supply unit faces the upstream side of each intake port 2a of each cylinder of the intake manifold 3. Further, an ignition plug 24 whose tip is exposed to the combustion chamber is attached to each cylinder of the cylinder head 2, and an igniter 25 is connected to the ignition plug 24.

On the other hand, a small-capacity sub fuel tank 28 for cold start is connected to a main fuel tank 26 for storing fuel for normal traveling via a first fuel passage 27. From the tank 28, the injector 2
A second fuel passage 30 extending from 3 to the pressure regulator 29 is extended.

As shown in FIG. 9, the second fuel passage 30
The injector 23 installed in the second fuel passage 30 is a side flow chart type injector.
Since a part of the fuel in the second fuel passage 30 is taken in from the side of the main body exposed to the inside of the pipe, the fuel circulated by the first and second fuel circulation systems described later is introduced into the injector. It is supplied and can always inject new fuel.

In the main fuel tank 26, only alcohol, mixed fuel of alcohol and gasoline, or only gasoline having different alcohol concentration M (%) is stored depending on the circumstances of refueling by the user. In addition, it has an in-tank type first fuel pump 31 for sending fuel under pressure to the first fuel passage 27.

In the first fuel passage 27, an electromagnetic wave 2
A first switching solenoid valve 32, which is a one-way valve, is interposed. The first switching solenoid valve 32 opens the first fuel passage 27 in a non-energized state, and opens the first fuel passage 27 when energized. 27 is to be closed.

The sub-fuel tank 28 has a fuel temperature sensor 33 attached to its side surface and a PTC pill (Positive Temperature Coefficient Pill) on its bottom surface.
A PTC heater 34 as a heating means including the above is attached, and the PTC heater 34 directly heats the fuel in the sub fuel tank 28.

A second fuel pump 35, a fuel filter 36, an alcohol concentration sensor 37, and the injector 23 are sequentially provided in the second fuel passage 30 from the side of the sub fuel tank 28. 2 Fuel passage 30
Part of the fuel pumped through the injector 23
And is supplied to the engine, and excess fuel is returned from the pressure regulator 29 through a second switching solenoid valve 38 which is an electromagnetic three-way valve.

The second switching solenoid valve 38 includes:
A first fuel return passage 39 connected to the main fuel tank 26 and a second fuel return passage 40 connected to the sub fuel tank 28 are connected to each other, and in a non-energized state, to the pressure regulator 29. When the first fuel return passage 39 is communicated with and energized, the pressure regulator 29 and the second fuel return passage 40 are communicated with each other.

The pressure regulator 29 is
This is a well-known diaphragm type regulator, which controls the return amount of fuel such that the pressure of the intake manifold 3 is introduced and the differential pressure between the pressure of the intake manifold 3 and the fuel pressure becomes constant.

The first switching solenoid valve 32 and the second switching solenoid valve 38 are energized or de-energized according to the start judgment result by the start-up control procedure described later, and are normally operated as the first fuel circulation system. Of the fuel circulation system and a path of the fuel circulation system as the second fuel circulation system when it is determined that the engine cannot be started.

That is, the path of the fuel circulation system in normal time is
When the first switching solenoid valve 32 and the second switching solenoid valve 38 are both non-energized, the main fuel tank 26, the sub fuel tank 28, the second fuel passage 30 and the pressure regulator 29 are connected. The fuel is returned to the main fuel tank 26 through the first fuel return passage 39.

On the other hand, the route of the fuel circulation system when the engine cannot be started is
With the first switching solenoid valve 32 and the second switching solenoid valve 38 both being energized, the main fuel tank 26 is separated from the sub fuel tank 28, and the fuel in the sub fuel tank 28 becomes the second fuel. It is a path that passes through the fuel passage 30 and returns from the pressure regulator 29 to the sub fuel tank 28 through the second fuel return passage 40.

Further, the alcohol concentration sensor 37 is
For example, it is a sensor that is composed of a pair of electrodes provided in the second fuel passage 30 and that detects the alcohol concentration by detecting a current change based on the electrical conductivity that changes depending on the alcohol concentration of the fuel. Alternatively, a resistance detection type, a capacitance type, an optical type sensor, or the like may be used.

An intake air amount sensor (a hot wire type intake air amount sensor in the figure) 41 is provided immediately downstream of the air cleaner 7 of the intake pipe 6, and the throttle valve 5a is provided with a throttle opening degree. The sensor 42 is arranged in series. Further, a knock sensor 43 is attached to the cylinder block 1a of the engine 1, and a cooling water temperature sensor 45 is exposed to a cooling water passage 44 communicating between the left and right banks of the cylinder block 1a, so that the exhaust manifold of the exhaust pipe 10 is exposed. O2 in the 9 gathering section
The sensor 46 is exposed.

A crank rotor 47 is rotatably mounted on a crank shaft 1b supported by the cylinder block 1a, and a crank angle sensor 48 including an electromagnetic pickup is provided on the outer periphery of the crank rotor 47. Further, a cam rotor 49 connected to the camshaft 1c of the engine 1 is provided with a cam angle sensor 50 for discriminating a cylinder composed of an electromagnetic pickup or the like. still,
The crank angle sensor 48 and the cam angle sensor 50
Is not limited to a magnetic sensor such as an electromagnetic pickup, but may be an optical sensor.

(Circuit Configuration of Engine Control System) In FIG. 8, reference numeral 51 is a control unit (ECU) composed of a microcomputer and the like, and a CPU 52, a ROM 53, and an RA.
The M54 and the I / O interface 55 are connected to each other via a bus line 56, and a constant voltage circuit 57 supplies a predetermined stabilizing voltage to each unit.

The constant voltage circuit 57 includes an ECU relay 58.
The relay coil of the ECU relay 58 is connected to the battery 59 via an ignition switch 60.

A starter motor 63 is connected to the battery 59 via relay contacts of a starter switch 61 and a starter motor relay 62, and a bottom surface of the sub fuel tank 28 via a relay contact of a heater relay 64 and a current sensor 65. The PTC heater 34 is connected, and further, the first fuel pump 31 and the second fuel pump 35 are connected via the relay contacts of the first fuel pump relay 66 and the second fuel pump relay 67, respectively.

The I / O interface 55 is also provided.
Of the absolute pressure sensor 22, the fuel temperature sensor 33, the alcohol concentration sensor 37, the intake air amount sensor 4
1, the throttle opening sensor 42, the knock sensor 43, the cooling water temperature sensor 45, the O2 sensor 46, the crank angle sensor 48, the cam angle sensor 50, the current sensor 65, and the starter switch 61 are connected, and the battery 59 is connected. Connected and battery voltage is monitored.

On the other hand, the I / O interface 55
The igniter 25 is connected to the output port of the ISCV 16, the wastegate valve controlling duty solenoid valve 21, the injector 23, the first switching solenoid valve 32, and the second switching valve via the drive circuit 68.
A switching solenoid valve 38, coils of each relay (starter motor relay 62, heater relay 64, first fuel pump relay 66, second fuel pump relay 67), and an ECS lamp 69 including an LED as a heater heating display means are provided. It is connected.

The ROM 53 stores control programs and fixed data such as various maps.
Further, the RAM 54 stores data after processing output signals of the sensors and switches and the CPU 52.
The data processed by the above is stored.

In the CPU 52, according to the control program stored in the ROM 53, when the ignition switch 60 is turned on at the time of engine start, a start determination is made, and the PTC heater 34 is energized / de-energized according to the judgment result. Is controlled, and the fuel circulation system is switched by the first switching solenoid valve 32 and the second switching solenoid valve 38, and the start-up control is executed.

(Start-up control procedure) The flowcharts of FIGS. 1 to 3 are programs for start-up control that start when the ECU 51 is turned on. First, in step S101, initialization is performed to start the starter motor relay 62,
Each of the heater relay 64, the first fuel pump relay 66, and the second fuel pump relay 67 is turned off, and each flag and count value are cleared.

Next, in step S102, the starter motor energization prohibition flag FLAG1 is set (FLAG
1 ← 1) When energization to the starter motor 63 is prohibited, in step S103, the startable determination temperature map MPTW is referenced with the alcohol concentration M from the alcohol concentration sensor 37 as a parameter with interpolation calculation to determine the startable determination temperature TSE.
Set T.

Next, in step S104, the cooling water temperature sensor 4
From 5, read the cooling water temperature TW as the engine temperature,
The cooling water temperature TW is compared with the startable judgment temperature TSET set in step S103 to make a start judgment.

That is, as shown in FIG. 10, the temperature condition region of the alcohol concentration M that can be started without heating the fuel and the temperature condition region that cannot be started as it is are specified by experiments, and the ROM 53 is used. From the startable determination temperature map MPTW (see FIG. 11) consisting of a series of addresses, the startable determination temperature T is set using the alcohol concentration M as a parameter.
Set SET. Then, this startable determination temperature TSET
By comparing the cooling water temperature TW with the cooling water temperature TW, it is determined whether the engine can be started.

As the engine temperature at the time of determining whether the engine can be started, a fuel temperature or the like may be adopted instead of the cooling water temperature TW from the cooling water temperature sensor 45.

As a result, in the step S104, TW> T
If it is set, it is determined that the engine can be started, the process proceeds to step S105, the heater relay 64 is turned off, and steps S106 and S10 are performed.
7, the first switching solenoid valve 32, the second
With the switching solenoid valve 38 de-energized, the first fuel passage 2 from the main fuel tank 26 to the sub fuel tank 28
7 is opened to form a normal fuel circulation system path that connects the pressure regulator 29 to the first fuel return passage 39 side.

Then, in steps S108 and S109, the first fuel pump relay 66 and the second fuel pump relay 67 are turned on, and in step S110, the starter motor energization prohibition flag F.
LAG1 is cleared (FLAG1 ← 0) to permit energization of the starter motor 63, and the program ends.

That is, normally, the main fuel tank 2
The fuel of No. 6 is pumped to the sub fuel tank 28 by the first fuel pump 31, the fuel is pumped to the second fuel passage 30 by the second fuel pump 35, and the pressure is regulated by the pressure regulator 29. The return from the pressure regulator 29 The injector 23 injects a part of the fuel in the fuel circulation system that returns the fuel to the main fuel tank 26 via the first fuel return passage 39.

The starter motor energization prohibition flag F
LAG1 is referred to by a starter motor control procedure described later. When the starter motor 63 is driven and the engine is cranked, the fuel of the fuel injection amount Ti set in the fuel injection control procedure described later is injected from the injector 23. It

On the other hand, in step S104, TW≤TSET
In the case of, it is determined that the engine cannot be started, the process branches to step S111, the heater relay 64 is turned on to start the energization of the PTC heater 34, and the ECS lamp 69 is turned on to notify the energization of the heater.

Next, in step S112, the timer operation flag FLAGTIMER is set (FLAGTIMER ←
1), the count value COUNT counted up by the timer routine of FIG. 4 which is interrupted at predetermined time intervals
Start counting.

The timer routine of FIG. 4 will now be described. This timer routine checks the value of the timer operation flag FLAGTIMER in step S201 to check FLAGTI.
When MER = 1, the process proceeds to step S202 and the count value CO
Count up UNT (COUNT ← COUNT
+1) When the routine is exited and FLAGTIMER = 0, the process branches to step S203 to clear the count value COUNT (COUNT ← 0) and exit the routine.

Next, in steps S113 and S114, the first switching solenoid valve 32 and the second switching solenoid valve 38
Is energized to close the first fuel passage 27 to shut off the main fuel tank 26 and the sub fuel tank 28, and
The fuel passage after the pressure regulator 29 is switched to the side of the second fuel return passage 40 to form a fuel circulation system passage at the time when the start failure is determined, and the routine proceeds to step S115.

In step S115, the fuel heating completion determination value COUNTSET for determining the heating completion when heating the fuel in the sub fuel tank 28 by the PTC heater 34 is set based on the cooling water temperature TW by map search or the like. .. This fuel heating completion determination value COUNTSET becomes larger as the cooling water temperature TW is lower, as shown in step S115. Also, the fuel heating completion determination value COUNT
SET is set to a smaller value as the heater capacity is larger, and is set to a larger value as the capacity of the sub fuel tank 28 is larger.

In order to simplify the control, the fuel heating completion determination value COUNTSET may be a preset unique value.

When the fuel heating completion determination value COUNTSET is set in step S115, the process proceeds to step S116, where the count value COUNT is the set fuel heating completion determination value C.
It is determined whether OUNTSET has been reached, and COUNT <C
If it is OUNTSET, the loop is repeated in step S116.

Thereafter, in step S116, COUNT
When ≥COUNTSET, the loop is exited and step S117
Then, the timer operation flag FLAGTIMER is cleared (FLAGTIMER ← 0), the second fuel pump relay 67 is turned on to operate the second fuel pump 35, and the heated fuel in the sub-fuel tank 28 is removed. The sub fuel tank 2 is pumped again from the pressure regulator 29.
Returning to 8, the fuel is circulated by the fuel circulation system when it is determined that the engine cannot be started.

Then, in step S119, the starter motor energization prohibition flag FLAG1 is cleared (FLAG1 ←
0) When the energization of the starter motor 63 is permitted and the engine is cranked, the fuel of the fuel injection amount Ti set in the fuel injection control procedure described later is injected from the injector 23, and the engine is initially detonated.

After that, in step S120, it is determined whether or not the engine speed NE has reached the complete explosion speed NESET (for example, 400 rpm). When NE≤NESET, the engine has not completed a complete explosion. Repeated explosion determination, NE ＞
When it becomes NESET, the process proceeds to step S121, the heater relay 64 is turned off to complete the heating by the PTC heater 34, and the ECS lamp 69 is turned off.

Next, the steps S121 to S122
Go to and turn on the first fuel pump relay 66, and step
In S123 and S124, the first switching solenoid valve 32 and the second switching solenoid valve 38 are de-energized to switch to the normal fuel circulation system described above, and the program ends.

That is, it is judged from the alcohol concentration and the cooling water temperature whether or not the fuel can be started without heating the fuel, and the fuel circulation system is switched at the cold start when it is judged that the fuel cannot be started. Since the fuel in the sub-fuel tank 28 having a small capacity is heated to a temperature at which it can be started by the PTC heater 34 and is supplied to the engine without using the fuel having a low temperature therein, the fuel is heated efficiently and reliably. The engine can be started.

Moreover, since the fuel is injected from the side flow type injector 23, the phase separation of the fuel occurs inside the injector like the top flow type injector in which the fuel is supplied only to the injector nozzle from above. There is no risk that low-temperature fuel will be injected without being replaced with the heated fuel, and the heated fuel can be immediately supplied to the engine to enable a quick start.

(Starter motor control procedure and fuel injection control procedure) On the other hand, as shown in FIG.
The program of the starter motor control procedure shown in FIG. 6 and the program of the fuel injection control procedure shown in FIG.

In the interrupt routine of the starter motor control procedure, first, in step S301, the starter switch 61 is turned off.
When it is determined that the starter switch 61 is ON, the process proceeds to step S302, the value of the starter motor energization prohibition flag FLAG1 is checked, and it is determined whether the energization of the starter motor 63 is permitted. ..

If FLAG1 = 0 in step S302, that is, if energization to the starter motor 63 is permitted, the process proceeds from step S302 to step S303 to turn on the starter motor relay 62 to turn on the starter motor 63.
To drive the engine to crank the engine and exit the routine.

On the other hand, when the starter switch 61 is OFF in step S301, or when FLAG1 = 1 in step S302 and the energization of the starter motor 63 is prohibited, each step branches to step S304. And turn off the starter motor relay 62.
Then, the starter motor 63 is stopped and the routine is exited.

In the interrupt routine of the fuel injection control procedure, at step S401, the engine speed NE is "
It is determined whether or not 0 ", that is, whether or not the engine is rotating. If NE ≠ 0, step S4
The routine proceeds from 01 to step S402 to call the fuel injection amount calculation routine, calculate the fuel injection amount Ti, set the fuel injection amount Ti in step S403, and exit the routine.
= 0 and the engine is stopped, step S401
To S404, the fuel injection amount Ti is set to "0" (Ti ← 0) and the routine is exited.

[Second Embodiment] FIGS. 12 and 13 relate to a second embodiment of the present invention. FIG. 12 is a flow chart showing a part of a control procedure at the time of start, and FIG. 13 is an explanatory view of a startable fuel temperature map. Is. In the second embodiment, the heating completion judgment when heating the fuel in the sub fuel tank 28 by the PTC heater 34 is set based on the alcohol concentration M and the cooling water temperature TW in comparison with the first embodiment. The judgment value is used for the judgment.

That is, in the flowchart of the control procedure at the time of start of the first embodiment, as a result of comparing the cooling water temperature TW with the startable determination temperature TSET in step S104 of FIG.
If TW ≦ TSET and it is determined that the engine cannot be started, steps S104 to S151 of the flowchart shown in FIG.
Branch to.

In step S151, the heater relay 64 is turned on.
When the PTC heater 34 is turned on and the energization of the PTC heater 34 is started, the step
In S152 and S153, the first switching solenoid valve 32 and the second switching solenoid valve 38 are energized to form the above-described fuel circulation system path at the time of the start failure determination, and the process proceeds to step S154.

In step S154, based on the alcohol concentration M and the cooling water temperature TW, the startable fuel temperature TFSET as the heating completion determination value is set by referring to the startable fuel temperature map MPTF shown in FIG. 13 with interpolation calculation. Step S155
Go to. This startable fuel temperature TFSET is the cooling water temperature TW
Is higher, and the higher the alcohol concentration M is, the higher the value is stored in the startable fuel temperature map MPTF.

In step S155, the fuel temperature TF in the sub fuel tank 28 detected by the fuel temperature sensor 33 is detected.
And the startable fuel temperature TFS set in step S154.
When TF <TFSET is compared with ET, the comparison is repeated in step S155 after waiting for the fuel temperature TF to rise by the PTC heater 34. When TF ≥TFSET, it is determined that the fuel heating is completed and the process proceeds to step S156. The second fuel pump relay 67 is turned on to operate the second fuel pump 35, and the heated fuel is pressure-fed.

The following steps S157 to S162 are the same as steps S119 to S124 of the above-described first embodiment. After the completion of the engine complete explosion, the normal fuel circulation system is switched to, and the program ends.

The other control procedures are the same as in the first embodiment, and similarly, the fuel can be efficiently heated and supplied to the engine, and the startability can be improved.

[Third Embodiment] FIGS. 14 and 15 relate to a third embodiment of the present invention. FIG. 14 is a flow chart showing a part of a starting control procedure, and FIG. 15 is a characteristic diagram of a PTC heater.

The third embodiment differs from the above-described first embodiment in determining whether heating is completed when the fuel in the sub fuel tank 28 is heated by the PTC heater 34 based on the current consumption characteristics of the PTC heater 34. The determination is made based on the set discriminant value, and the process of step S1550 is performed instead of steps S154 and S155 of the starting control procedure of the second embodiment.

That is, in steps S152 and S153, the first switching solenoid valve 32 and the second switching solenoid valve 3
8 is energized to switch to the fuel circulation system when it is determined that the engine cannot be started, the process proceeds from step S153 to step S1550, and the consumption current I of the PTC heater 34 detected by the current sensor 65 is detected.
And the discriminant value ISET are compared.

PTC heater 3 comprising a PTC thermistor
As shown by the alternate long and short dash line in FIG. 15, No. 4 has the characteristic that when the temperature rises and reaches the Curie point after energization, the resistance value sharply rises and the consumption current I decreases. When only is heated and is not vaporized, the current consumption I is saturated at a predetermined value and becomes constant as shown by the solid line in the figure.

Therefore, it is possible to judge the completion of heating of the fuel by using the current value ISET before the consumed current I reaches the saturation as a judgment value. When I> ISET in step S1550,
It is determined that heating is completed and the process proceeds to step S156 described above.
After this step S156, similar processing is performed.

It goes without saying that the same effects as those of the above-described embodiments can be obtained in this embodiment as well.

[0096]

As described above, according to the present invention, the fuel is efficiently heated and supplied to the engine according to the alcohol concentration of the fuel, so that the engine can be reliably started and the startability is improved. An excellent effect such as being able to be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a flow chart showing a start-up control procedure according to the first embodiment of the present invention.

FIG. 2 is a flowchart showing a start-up control procedure according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a control procedure at the time of starting 3 according to the first embodiment of the present invention.

FIG. 4 is a flowchart of a timer routine according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing a control procedure of the starter motor according to the first embodiment of the present invention.

FIG. 6 is a flowchart showing a fuel injection control procedure according to the first embodiment of the present invention.

FIG. 7 is a schematic diagram of an engine control system according to the first embodiment of the present invention.

FIG. 8 is a circuit configuration diagram of an engine control system according to the first embodiment of the present invention.

FIG. 9 is a sectional view of a side flow type injector according to the first embodiment of the present invention.

FIG. 10 is an explanatory view showing a startable region and a non-startable region according to the first embodiment of the present invention.

FIG. 11 is an explanatory diagram of a startable determination water temperature map according to the first embodiment of the present invention.

FIG. 12 is a flowchart showing a part of a starting control procedure according to the second embodiment of the present invention.

FIG. 13 is an explanatory diagram of a startable fuel temperature map according to the second embodiment of the present invention.

FIG. 14 is a flowchart showing a part of a starting control procedure according to the third embodiment of the present invention.

FIG. 15 is a characteristic diagram of a PTC heater according to the third embodiment of the present invention.

[Explanation of symbols]

 23 Side flow type injector 26 Main fuel tank 28 Sub fuel tank 34 PTC heater COUNTSET Fuel heating completion judgment value M Alcohol concentration TW Cooling water temperature I Current consumption

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location F02D 45/00 364 K 8109-3G F02M 31/12 311 E 8923-3G F02N 11/08 G 9149- 3G

Claims (9)

[Claims] 1. A non-startable procedure based on the alcohol concentration of the fuel and the engine temperature, a procedure for determining whether the engine can be started without heating the fuel, and a procedure for determining whether the engine can be started. When it is determined that the first fuel circulation system uses the main fuel tank as a fuel delivery source and a return destination, the second fuel uses a sub fuel tank connected to the main fuel tank as a fuel delivery source and a return destination. A procedure of switching to a circulation system; a procedure of heating the fuel in the sub fuel tank by a heating means when it is determined that the engine cannot be started in the procedure of determining whether or not the engine can be started; and a fuel in the sub fuel tank. Based on the discriminant value set in the procedure for setting the discriminant value for determining whether or not the heating is completed, and the procedure for setting the discriminant value,
When it is determined that the heating is completed in the procedure for determining whether the heating of the fuel in the sub-fuel tank by the heating means is completed and the procedure for determining whether the heating of the fuel is completed, the second And a procedure for supplying fuel from the fuel circulation system to the engine.
FV engine starting control method. 2. The FFV according to claim 1, wherein the discriminant value in the procedure for setting the discriminant value is set as a heating time of the heating means based on a cooling water temperature.
Engine start control method. 3. The start control of an FFV engine according to claim 1, wherein the discriminant value in the procedure for setting the discriminant value is set as a fuel temperature based on an alcohol concentration of fuel and a cooling water temperature. Method. 4. The heating means in the heating procedure is an electric heater, and the discriminant value in the procedure for setting the discriminant value is set as a predetermined current consumption value of the electric heater. FFV engine start control method. 5. The first fuel is shut off from the sub fuel tank and the fuel return passage is switched from the main fuel tank side to the sub fuel tank side in the switching procedure. 2. The start control method for an FFV engine according to claim 1, wherein a supply system is switched to the second fuel supply system. 6. A first fuel circulation system having a main fuel tank as a fuel delivery source and a return destination, and a second fuel circulation system having a sub fuel tank connected to the main fuel tank as a fuel delivery source and a return destination. Switching means capable of selectively switching the system, fuel supply means for supplying a part of fuel circulated by the first fuel circulation system or the second fuel circulation system to the engine, the sub fuel tank A starting control device for an FFV engine, comprising: a heating unit for heating the fuel inside. 7. The switching means comprises a first switching valve provided between the main fuel tank and the sub fuel tank, and a second switching valve provided in a fuel return passage. The starting control device for an FFV engine according to claim 6. 8. The fuel supply means is constituted by a side flow type injector for injecting a part of the fuel in the fuel pipe into the interior from a side of the main body facing the fuel pipe and injecting the fuel. The FFV according to claim 6.
Engine start control device. 9. The starting control device for an FFV engine according to claim 6, wherein the heating means is an electric heater that directly heats the fuel in the sub fuel tank.