JP2002349305A - Electronic controller for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic controller for an internal combustion engine capable of improving the startability at the low temperature in the internal combustion engine in which two kinds of fuels including the gas fuel are used. SOLUTION: An electronic control unit 30 judges whether or not the fuel supplied during a stop is a gas fuel when the internal combustion engine starts after its stop. When judging the supplied fuel during a stop to be a gas fuel, a fuel injection valve 4 effects opening and closing operation with a valve for fuel supply closed. A fuel pressure in the fuel injection valve 4 is emitted until becoming a predetermined value or less to scavenge in the fuel injection valve 4. When the fuel pressure in the fuel injection valve 4 drops to the predetermined value or less by this scavenging operation, the valve for the fuel supply is opened and the fuel (for instance, gasoline) for the start is supplied to the fuel injection valve 4 to start the internal combustion engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Electronic control unit for an internal combustion engine using different types of fuels,
In particular, the present invention relates to an electronic control unit that uses gas fuel to improve startability after an internal combustion engine is stopped.

[0002]

2. Description of the Related Art Conventionally, an internal combustion engine using gasoline or ethanol as a first fuel and a gas fuel such as LPG or CNG as a second fuel has been proposed in consideration of fuel economy. It is known from, for example, JP-A-502472. An internal combustion engine using two types of fuels of this type selectively supplies two types of fuel to a set of fuel injection valves and injects the two types of fuel per unit weight or unit volume. Because the combustion energy is different, the first fuel or the second fuel arbitrarily selected, or both fuels alternately, the injection timing and the fuel injection amount are appropriately controlled, and supplied into the cylinder, The engine is operated.

[0003]

However, for example, in an internal combustion engine using gasoline as the first fuel and gaseous fuel as the second fuel, when starting the engine, gasoline as the first fuel having good ignitability is usually used. Although it is supplied to the injection valve, when starting at low temperature in a cold region or the like, if the conditions are poor, there is a problem that the starting takes a long time and the cranking time becomes longer.

That is, the internal combustion engine is operated by selectively supplying two types of fuel to a set of fuel injection valves and injecting the fuel into a cylinder at an appropriate injection timing. When the engine is stopped at the time of supply to the fuel injection valve, gas fuel remains in the fuel injection valve. After that, if the engine is cranked by turning the starter in a cold low temperature state, the gas fuel in the fuel injection valve is injected into the cylinder without vaporizing because the gas fuel has a low temperature and is difficult to vaporize. As a result, the inside of the cylinder is further subcooled, resulting in deterioration of fuel atomization. As described above, when the gaseous fuel is used as the second fuel, there is a problem that the ignitability at the time of low-temperature start is poor, and it takes time to start the engine.

[0005] The present invention has been made in view of the above points, and in an internal combustion engine using two types of fuels including gaseous fuel, an electronic control unit for an internal combustion engine capable of improving the startability at low temperatures. The purpose is to provide.

[0006]

In order to achieve the above object, an electronic control unit for an internal combustion engine according to the present invention selectively supplies two types of fuels including gaseous fuel to a set of fuel injection valves. In an electronic control unit for an internal combustion engine that injects fuel, a fuel storage unit that stores a type of fuel that has been supplied to the fuel injection valve when the internal combustion engine stops, and when the internal combustion engine starts after the stop, Fuel determining means for determining whether or not the supplied fuel is gaseous fuel, and when the internal combustion engine is started, the fuel determining means is based on the storage content of the fuel storage means, and the gas fuel is supplied at the time of the stop. If determined, in a state where the fuel supply valve is closed, the fuel injection valve is opened and closed, scavenging means for purging the fuel injection valve by discharging the fuel pressure in the fuel injection valve to a predetermined value or less, With scavenging means When the fuel pressure in the fuel injection valve falls below a predetermined value due to the operation, the fuel supply valve is opened, and the fuel for starting is supplied to the fuel injection valve to start the internal combustion engine. And

Here, a fuel changeover switch for selecting and determining the fuel to be used from two types of fuels can be provided. In addition, gas fuel and gasoline are used as two types of fuel, and gasoline is always supplied to the fuel injection valve at the time of starting, so that good startability in a cold state can be secured.

[0008]

In the electronic control device for an internal combustion engine having the above-described structure, when the internal combustion engine stops, the type of fuel supplied to the fuel injection valve is stored in the fuel storage means. When the internal combustion engine is started after stopping, the fuel determining means determines whether or not the fuel supplied at the time of stopping is gas fuel based on the contents stored in the fuel storing means. At this time, if the fuel determining means determines that gaseous fuel was being supplied at the time of the stop, the scavenging means opens and closes the fuel injection valve with the fuel supply valve closed, and sets the fuel pressure in the fuel injection valve. Until the value becomes equal to or less than a predetermined value to scavenge the inside of the fuel injection valve. Then, the fuel pressure in the fuel injection valve is reduced to a predetermined value or less by the operation of the scavenging means, and when the scavenging is completed, the fuel supply valve is opened,
A starting fuel (for example, gasoline) is supplied to the fuel injection valve to start the internal combustion engine.

As described above, when the internal combustion engine is stopped while using gaseous fuel, the gaseous fuel remains in the fuel injector, but when the engine is started next time, the gaseous fuel remaining in the fuel injector remains. Since the internal combustion engine is started by supplying the starting fuel (for example, gasoline) to the fuel injection valve after starting the scavenging operation, when starting the engine at a low temperature in a cold region, it is difficult to vaporize the gas at a low temperature. The fuel is not injected from the fuel injection valve, and gasoline is immediately injected from the fuel injection valve at the time of cranking, so that the cold start of the internal combustion engine can be performed reliably and quickly.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a fuel injection control device for an internal combustion engine to which the present invention is applied, and FIG. 2 is an enlarged view of a main part of the device. Reference numeral 1 denotes an engine main body, an intake manifold 2 and an exhaust manifold 3 are connected to its cylinder head, and a fuel injection valve 4 is provided for each cylinder in the intake manifold 2.

A first delivery pipe 5 for sending gasoline as a first fuel and a second delivery pipe 6 for sending gaseous fuel as a second fuel are connected to the fuel injection valve 4. Valve 8 is provided, and the second delivery pipe 6 is provided with a gas fuel valve 9. Further, a fuel pressure sensor 7 is provided above the fuel injection valve 4 to detect a residual fuel pressure in the injection valve.

An upstream side of the intake manifold 2 of the engine body 1 is connected to an intake pipe 11 via a surge tank 10, and an air cleaner 13 is provided upstream of the intake pipe 11. Throttle valve 12
Is provided. An intake pressure sensor 21 for detecting the intake pipe pressure is attached to the surge tank 10. On the other hand, the exhaust manifold 3 is provided with an O ₂ sensor 14 for detecting the residual oxygen concentration in the exhaust, and a three-way catalyst 15 is provided in an exhaust pipe connected to the exhaust manifold 3 to detect the temperature thereof. A temperature sensor 16 is provided.

The first delivery pipe 5 is connected to a gas tank 17 via a gasoline pump 19, and the second delivery pipe 6 is connected to a gas fuel tank 18 via a gas fuel pump 20. The gasoline tank 17 is filled with gasoline as the first fuel, and the gas fuel tank 1
8 is filled with a gas fuel such as LPG and CNG as a second fuel. The gasoline pump 19 may be installed inside or outside the gasoline tank 17, and the gas fuel pump 20 may be installed inside or outside the gas fuel tank 18.

Reference numeral 30 denotes an electronic control unit which mainly performs fuel injection control of the internal combustion engine.
The main part is a microcomputer including a CPU, a ROM, a RAM, an input / output circuit, and the like. Based on program data stored in the ROM in advance, a fuel injection control process or a fuel in the fuel injection valve 4 at the time of starting is performed. (E.g., discharging fuel).

In the fuel injection control, for example, a basic injection amount (time) is calculated from the detected and calculated intake air amount and the engine speed, and the basic injection amount is corrected for the intake air temperature based on the detected intake air temperature, and the detected cooling is detected. The fuel injection amount (time) is calculated by performing a warm-up increase correction based on the water temperature, an air-fuel ratio feedback correction for bringing the air-fuel ratio detected by the O ₂ sensor 14 close to a theoretical value, and the like. Then, based on the calculated fuel injection amount, the fuel injection valve 4 of each cylinder is controlled to open and close at a predetermined injection timing.

The input / output circuits of the electronic control unit 30 include:
As output system, the fuel injection valve 4, gasoline valve 8, the gas fuel valve 9, the gasoline pump 19, is connected to a gas fuel pump 20, as an input system, a fuel pressure sensor 7, O ₂ sensor 14, the temperature sensor 16, the intake pressure sensor 21, and the fuel switch 22 are connected.

The fuel changeover switch 22 is a manual switch used when the user switches and sets the fuel to be used arbitrarily. For example, when the fuel changeover switch 22 is changed and set to the second fuel side, a gas switch is used. The fuel valve 9 is opened, the gasoline valve 8 is closed, and gas fuel is sent from the gas fuel tank 18 to the fuel injection valve 4 through the pump 20. On the other hand, when the fuel switch 22 is switched and set to the first fuel side, the gasoline valve 8 is opened, the gas fuel valve 9 is closed, and gasoline is sent from the gasoline tank 17 to the fuel injection valve 4 through the pump 19. Can be

The fuel switch 22 is provided with a structure for mechanically storing the switched state or a function for electrically storing the switched state. Further, information on the fuel (first fuel or second fuel) switched and set by the fuel switch 22 can be stored in a memory in the electronic control unit 30.

Next, a scavenging operation in the fuel injection valve 4 performed when the internal combustion engine is started will be described with reference to flowcharts of FIGS. In this internal combustion engine, the user can arbitrarily select the fuel to be used by the fuel switch 22. For example, when the fuel switch 22 is switched and set to the second fuel side, the gas fuel valve 9 Is opened, the gasoline valve 8 is closed, and gaseous fuel is sent from the gaseous fuel tank 18 to the fuel injection valve 4 through the pump 20.

The electronic control unit 30 calculates a fuel injection amount (time) based on data such as an intake air amount, an engine speed, and a temperature sensor detected by various sensors.
Based on the fuel injection amount (time), the fuel injection valve 4 is controlled to open and close at a predetermined time, the fuel sent to the fuel injection valve 4 is injected into the cylinder, and the operation of the engine is controlled.

When the ignition switch is turned off, the internal combustion engine is once stopped, and then the engine is started again, processing as shown in FIGS. 3 and 4 is executed. That is, step 1
When the ignition switch is turned on to start the engine at 00, next, at step 110, it is determined whether or not the supplied fuel at the time of the previous stop was the gaseous fuel of the second fuel by the switching information of the fuel switch 22. Determined by If the fuel switch 22 is currently switched to or set to the second fuel when the engine is stopped, it is determined that the gaseous fuel of the second fuel was being used when the engine was stopped.

On the other hand, if the fuel switch 22 has been switched to the first fuel at present or when the engine is stopped, it is determined that gasoline as the first fuel has been used at the previous stop, and the fuel injection is performed. The process proceeds to step 160 without performing the scavenging process of the residual fuel in the valve 4.

In step 120, the gasoline valve 8 and the gas fuel valve 9 are closed.
At 30, the residual fuel in the fuel injection valve 4 is scavenged (the fuel is discharged). Specifically, as shown in FIG. 4, first, at step 132, the fuel injection valve 4 is opened and closed several times, and the gas fuel remaining inside is discharged through the nozzle of the fuel injection valve 4. Next, at step 134, based on the detection data from the fuel pressure sensor 7 for detecting the residual fuel pressure in the fuel injection valve 4, the residual fuel pressure becomes 0.3M.
It is determined whether it has become equal to or less than pa. This step 13
In step 4, the opening / closing operation of the fuel injection valve 4 in step 132 is repeated until the residual fuel pressure becomes 0.3 Mpa or less,
If the gaseous fuel is sufficiently discharged and becomes 0.3 Mpa or less, the process proceeds to step 136, and the opening / closing operation of the fuel injection valve 4 is stopped.

When the scavenging process of the residual fuel in the fuel injection valve 4 is completed, the driving of the gasoline pump 19 is controlled in step 140 in FIG.
At 0, the gasoline valve 8 is opened and closed, and the routine proceeds to step 160, where the starter is driven to perform the cranking operation of the engine and the calculated fuel injection amount (time).
, The fuel injection valve 4 is controlled to open at a predetermined timing, an ignition plug is ignited at a predetermined ignition timing, and gasoline injected into the cylinder is ignited to start the engine.

After the engine is started, if the fuel switch 22 is switched to gas fuel, the gasoline pump 19 is stopped to drive the gas fuel pump 20, and the gasoline valve 8 is closed to close the gas fuel. Open the fuel valve 9 to supply gaseous fuel to the fuel injection valve 4;
Operate the engine with gas fuel.

As described above, when the engine is stopped while using the gaseous fuel as the second fuel, the gaseous fuel remains in the fuel injection valve 4, but when the engine is started next time, the gaseous fuel remains in the fuel injection valve 4. The remaining gas fuel is discharged by the scavenging operation of the fuel injection valve 4. Then, in this state, the gasoline for starting is supplied to the fuel injection valve 4 to start the engine. Therefore, when the engine is started at a low temperature in a cold region or the like, the gas fuel remaining inside the fuel injection valve 4 is reduced. It is not discharged. Therefore, gas fuel that is difficult to vaporize at low temperatures is not injected, and gasoline is immediately injected from the fuel injection valve at the time of cranking, so that the engine can be started reliably and quickly.

In the above embodiment, the fuel switch 22 is provided so that the user can selectively switch and set the first fuel or the second fuel. Automatically and alternately, or basically supply the first fuel continuously, and automatically switch to the second fuel and supply it to the fuel injection valve only when a specific operating condition is satisfied. You can also. In addition, ethanol or the like can be used as the first fuel in addition to gasoline.

[0028]

As described above, according to the electronic control apparatus for an internal combustion engine of the present invention, when the internal combustion engine is stopped while using gas fuel, the gas fuel remains in the fuel injection valve. When starting the engine, the gas fuel remaining in the fuel injection valve is discharged by the scavenging operation, and thereafter, the starting fuel (for example, gasoline) is supplied to the fuel injection valve to start the internal combustion engine. When starting the engine at low temperature in the ground, gas fuel that is difficult to vaporize at low temperature is not injected from the fuel injection valve, and gasoline is immediately injected from the fuel injection valve at the time of cranking, and when the internal combustion engine is cold, The starting can be performed reliably and quickly.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an electronic control unit for an internal combustion engine showing an embodiment of the present invention.

FIG. 2 is an enlarged configuration diagram of a main part of the apparatus.

FIG. 3 is a flowchart showing an operation process at the time of starting the engine.

FIG. 4 is a flowchart showing a scavenging operation of a fuel injection valve.

[Explanation of symbols]

 4-fuel injection valve 7-fuel pressure sensor 8-gasoline valve 9-gas fuel valve 22-fuel changeover switch 30-electronic control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 21/02 301 F02M 21/02 301C 301L 301R F02N 17/08 F02N 17/08 H F term (Reference) 3G084 AA05 BA09 BA13 BA14 BA15 BA28 CA01 DA09 EA04 EB06 EC01 FA02 FA07 FA11 FA14 FA20 FA33 FA36 3G092 AA08 AB12 BB01 BB06 BB08 DE01S EA11 EA12 EA29 FA21 FA31 GA01 HA01Z HA05Z HB03Z HB05Z HE01Z HE08Z0101 PE08Z PF16Z

Claims (3)

[Claims] An electronic control unit for an internal combustion engine that selectively supplies two types of fuels including gaseous fuel to a set of fuel injection valves and injects the fuel. Fuel storage means for storing the type of fuel supplied; fuel determination means for determining whether fuel supplied at the time of stopping the internal combustion engine is gaseous fuel when the internal combustion engine is started after stopping; and starting the internal combustion engine. When the fuel determining means determines that the gas fuel has been supplied at the time of the stop based on the stored contents of the fuel storing means, the fuel injection valve is opened and closed with the fuel supply valve closed. Scavenging means for discharging the fuel pressure in the fuel injection valve to a predetermined value or less and scavenging the inside of the fuel injection valve, wherein the operation of the scavenging means reduces the fuel pressure in the fuel injection valve to a predetermined value or less. When it drops to Fee opening the valve for supplying the electronic control apparatus for an internal combustion engine by supplying the fuel for starting the fuel injection valve, characterized by being configured so as to start the internal combustion engine. 2. The electronic control unit for an internal combustion engine according to claim 1, further comprising a fuel changeover switch for selecting and determining a fuel to be used from two types of fuels. 3. The electronic control unit for an internal combustion engine according to claim 1, wherein gas fuel and gasoline are used as the two types of fuel, and gasoline is always supplied to the fuel injection valve and injected at the time of starting.