JP3740975B2 - Fuel heating control method for fuel adhesion on working wall - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine of a vehicle such as an automobile, and more particularly to operation control of a heater for heating the fuel.
[0002]
[Prior art]
In the engine for the above-mentioned use, it has been performed for a long time to provide an electric heater in a fuel injection valve for injecting fuel and to heat and inject the fuel by heating the fuel injection valve with the heater. Various inventions have also been proposed in which the heating of fuel by such a heater is controlled based on the atmosphere, the temperature state of the engine, or the combustion state of the fuel. An example of such an invention is disclosed in Japanese Patent Application Laid-Open No. 11-148441.
[0003]
In order to improve the startability of the engine by heating the fuel heater, these conventional proposals are not limited to the heating mode depending on the atmosphere, the engine temperature state, or the fuel combustion state. This invention relates to whether or not
[0004]
[Problems to be solved by the invention]
However, such a fuel heating heater has another effect in addition to the improvement of the startability of the engine. That is to improve the exhaust properties when starting the engine.
[0005]
The present invention pays attention to the aspect of improving the exhaust property at the time of starting the engine in the heater for heating the fuel of the engine. From this viewpoint, it is an object to improve the operation control of the heater.
[0006]
[Means for Solving the Problems]
In a way to control the operation of the heater that heats the engine fuel,
Estimates the amount of fuel that adheres to the operation wall of the engine,
Operating the heater when the estimated amount of fuel adhering to the operating wall is equal to or greater than a predetermined threshold ;
The present invention proposes a method in which the operation of the heater is stopped when the amount of fuel on the operating wall surface becomes equal to or less than a predetermined threshold value . Here, the operating wall surface of the engine refers to a wall surface involved in the action of converting the thermal energy of the fuel into mechanical energy called motive power, such as the inner wall surface of the intake port and the inner wall surface of the combustion chamber.
[0007]
In the fuel heating heater operation control method, the estimation of the amount of fuel attached to the operation wall surface may be performed based on at least the fuel injection amount, the engine speed, and the intake pipe pressure.
[0008]
Alternatively, in the above-described fuel heating heater operation control method, the estimation of the amount of fuel attached to the operation wall surface may be performed based on at least the fuel injection amount and the air-fuel ratio of the engine exhaust.
[0009]
[Action and effect of the invention]
As described above, the fuel heating heater of the engine has an aspect that the exhaust property at the time of starting the engine can be improved in addition to improving the startability of the engine. This is because when the engine is cold started and the engine wall surface is cold, fuel mist droplets injected from the fuel injectors tend to adhere to the wall surface. Therefore, fuel supply with a richer air-fuel ratio is required, and as a result, the amount of unburned fuel such as HC in the engine exhaust increases. This is to reduce the amount of fuel adhering to the working wall, eliminate the need for air-fuel ratio enrichment, and prevent the discharge of unburned fuel. In this case, if it does not matter whether the amount of electric power consumed for the operation of the heater is large or small, in order to exert the effect of the fuel heating heater greatly in such a situation, the energization to the heater started at the start of the engine is However, it may be continued until a moderate warm-up state is reached and no fuel adheres to the working wall, but the power consumption of such a fuel heating heater is insignificant.
[0010]
In this respect, after starting energization of the heater at the start of the engine as described above, the amount of fuel adhering to the operating wall surface of the engine is estimated, and the operating wall adhering fuel amount is equal to or greater than a predetermined threshold value. If the operation is limited so that the heater is activated, that is, the operation of the heater is stopped when the amount of fuel adhering to the working wall falls below a predetermined threshold value, the unburned due to fuel adhering to the working wall The operation of the heater for heating the fuel from the aspect of eliminating the minute discharge can be performed most efficiently with the minimum power consumption. From this point of view, the suppression of power consumption by controlling the operation of the heater for heating the fuel is not only limited to the conventional battery, but particularly in the hybrid vehicle, which will become increasingly important in the future to save fuel resources and protect the environment. It is important for equipment performance maintenance.
[0011]
The amount of fuel adhering to the engine operating wall is first governed by the fuel injection amount, and further increases as the engine speed increases and increases as the intake pipe pressure increases. Therefore, in the above configuration, if the estimation of the fuel amount attached to the engine working wall surface is made based on at least the fuel injection amount, the engine speed, and the intake pipe pressure, the fuel amount attaching to the working wall surface is estimated with high accuracy. By controlling the operation of the heater based on this, the operation purpose of the heater to eliminate the adhesion of fuel to the operation wall surface can be effectively achieved with a minimum power consumption.
[0012]
Alternatively, since the degree of fuel adhering to the working wall surface at the time of engine cold start when the heater is operated can be estimated from the air-fuel ratio of the engine exhaust, the fuel adhering to the working wall surface in the above-described configuration. The estimation of the amount can be performed with high accuracy even based on at least the fuel injection amount and the air-fuel ratio of the engine exhaust, and even with this method, the operation purpose of the heater, which eliminates the adhesion of fuel to the working wall surface, is minimized. Effectively achieved with power consumption.
[0013]
In any case, it is much earlier than the warm-up time of the engine, which is usually judged by the temperature of the engine cooling water, so that the unburned exhaust in the engine exhaust due to the fuel adhering to the engine working wall surface is settled. In this way, turning off the fuel heating heater when the fuel no longer adheres to the working wall surface is effective for suppressing the discharge of unburned fuel into the atmosphere at the time of engine cold start without reducing its effect. In addition, power consumption is reduced by keeping the heater on until the engine warms up.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 attached herewith is a schematic diagram showing a main part of an engine for carrying out the method of the present invention and a device around it. In the figure, reference numeral 1 denotes a cylinder portion of an engine, and an intake port 5 and an exhaust port 6 which are opened and closed by an intake valve 3 and an exhaust valve 4 respectively open in a combustion chamber 2 formed in the upper portion thereof. ing. A fuel injection valve 7 is provided in the intake port 5 so as to inject fuel toward the opening of the port. A throttle valve 9 is provided in the middle of the intake passage 8 leading to the intake port. An exhaust passage 10 is connected to the exhaust port 6, and a catalytic converter 11 incorporating an exhaust purification catalyst such as a three-way catalyst is further connected to the exhaust port 6. Reference numeral 12 denotes a spark plug.
[0015]
The fuel injection valve 7 is provided with a heater 13 that surrounds the fuel injection valve 7 and can heat the injected fuel. The heating of the fuel according to the present invention is not limited to the heating of the fuel at the portion of the fuel injection valve. The intake passage 8 is provided with an intake pipe pressure sensor 14 for detecting the intake pipe pressure. The exhaust passage 10 is provided with an air-fuel ratio sensor 15 that can detect whether the engine is operating at a stoichiometric air-fuel ratio or higher or a stoichiometric air-fuel ratio or lower by detecting residual oxygen in the exhaust gas. ing.
[0016]
The fuel injection supply by the fuel injection valve 7, the intake throttling by the throttle valve 9, the fuel ignition by the spark plug 12, and the heating of the fuel injection valve by the heater 13 are respectively performed by the electric vehicle operation control device 16 equipped with a computer. Control is performed via a valve drive circuit 17, a throttle valve drive circuit 18, a spark plug drive circuit 19, and a heater drive circuit 20. The electric vehicle operation control device 16 includes a key switch SW1 (not shown in the drawing) for a signal related to on / off, a starter switch SW2 for a signal related to on / off of the starter, a signal indicating the depression amount Dp from the accelerator pedal, vehicle speed. A signal indicating the vehicle speed Sv is supplied from the sensor, a signal indicating the engine speed Ne is supplied from the engine speed sensor, and a signal indicating the engine coolant temperature Te is supplied from the engine coolant temperature sensor. In addition, the intake pipe pressure sensor 14 A signal indicating the intake pipe pressure and a signal indicating the air-fuel ratio of the engine operation are supplied from the air-fuel ratio sensor 15.
[0017]
When an engine having such a configuration is started by a signal from the switches SW1 and SW2, the electric vehicle operation control device 16 sends a signal related to the accelerator pedal depression amount Dp from the accelerator pedal, an engine speed Ne from the engine speed sensor. And the additional fuel to be added to the basic fuel injection amount in accordance with the engine speed Ne and the engine coolant temperature Te. The injection amount is calculated, and the fuel injection valve drive circuit 17, the throttle valve drive circuit 18, and the spark plug drive circuit 19 are operated based on these calculation results to control the start-up to the complete explosion of the engine and the subsequent output. .
[0018]
At the same time, the electric vehicle operation control device 16 determines whether or not the engine start is a cold start based on the engine coolant temperature Te, that is, whether or not the heater 13 needs to be operated here. If it is determined, a command is issued to the heater drive circuit 20 to operate the heater 13. When the heater is operated, the electric vehicle operation control device 16 continues based on at least the fuel injection amount by the sum of the basic fuel injection amount and the additional fuel injection amount, the engine speed, and the intake pipe pressure. Or an engine such as the inner wall surface of the intake port or the inner wall surface of the combustion chamber of the injected fuel based on at least the fuel injection amount obtained by adding the basic fuel injection amount and the additional fuel injection amount and the air-fuel ratio of the engine exhaust. The amount of fuel estimated to adhere to the working wall is estimated and calculated. The estimated calculation of the amount of fuel attached to the working wall uses at least the fuel injection amount, the engine speed and the intake pipe pressure, or at least the fuel injection amount and the air / fuel ratio of the engine exhaust as variable parameters, respectively. An appropriate map for deriving the amount of fuel is created in advance based on experiments, and is incorporated into a ROM in the computer section of the electric vehicle operation control device 16 to achieve this at each moment during engine start operation.
[0019]
Thus, the operation of the heater 13 is monitored while monitoring the amount of fuel adhering to the working wall obtained at each instant by the above estimation calculation, and this adhering amount is lowered to a value that allows the discharge of unburned fuel into the engine exhaust. And the process is continued until a predetermined threshold value estimated in advance is reached. When the adhesion amount falls below the threshold value, the electric vehicle operation control device 16 issues a command to the heater drive circuit 20 to stop the operation of the heater 13.
[0020]
The stopping of the heater based on the monitoring of the amount of fuel attached to the working wall occurs considerably ahead of the conventional concept of achieving the engine warm-up based on the engine coolant temperature, but the amount of fuel attached to the working wall is estimated. In such an engine (that is, an engine of a vehicle equipped with the electric vehicle operation control device 16), the electric vehicle operation control device 16 is already driven by the fuel injection valve by air-fuel ratio feedback control based on the output signal of the air-fuel ratio sensor 15. Since the circuit 17 is operated and proper control of fuel supply is started, if the fuel adheres substantially to the operation wall, the unburned fuel is no longer discharged by the correct control of the air-fuel ratio. . In addition, the heater block according to the present invention precedes the conventional engine warm-up concept based on the engine coolant temperature. The cylinder block and cylinder head constituting the combustion chamber and intake port of the engine are And a water jacket that circulates cooling water through them, and the wall surface temperature that is functionally meaningful by the heat capacity due to this wall thickness and the temperature difference across it. There is a circumstance that a large time delay occurs between the temperature of the cooling water flowing in the water jacket. The present invention eliminates such time delay, thereby reducing power consumption by the heater without reducing the effect of fuel heating by the heater.
[0021]
While the invention has been described in detail with reference to an embodiment thereof, it will be apparent to those skilled in the art that various modifications may be made to the embodiment without departing from the scope of the invention.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a main part of an engine for carrying out the method of the present invention and a device around the engine.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine cylinder head part 2 ... Combustion chamber 3 ... Intake valve 4 ... Exhaust valve 5 ... Intake port 6 ... Exhaust port 7 ... Fuel injection valve 8 ... Intake passage 9 ... Throttle valve 10 ... Exhaust passage 11 ... Catalytic converter 12 ... Spark plug 13 ... Heater 14 ... Intake pipe pressure sensor 15 ... Air-fuel ratio sensor 16 ... Electric vehicle operation control device 17 ... Fuel injection valve drive circuit 18 ... Throttle valve drive circuit 19 ... Spark plug drive circuit 20 ... Heater drive circuit

Claims (3)

In a way to control the operation of the heater that heats the engine fuel,
Estimates the amount of fuel that adheres to the operation wall of the engine,
Operating the heater when the estimated amount of fuel adhering to the operating wall is equal to or greater than a predetermined threshold;
The method is characterized in that the operation of the heater is stopped regardless of the engine cooling water temperature when the amount of fuel attached to the working wall surface falls below a predetermined threshold value.   The method according to claim 1, wherein the estimation of the amount of fuel attached to the working wall is performed based on at least a fuel injection amount, an engine speed, and an intake pipe pressure.   The method according to claim 1, wherein the estimation of the amount of fuel attached to the working wall is performed based on at least a fuel injection amount and an air-fuel ratio of engine exhaust.

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