JP3044719B2 - Throttle valve control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method of controlling a throttle valve in an internal combustion engine in which opening and closing of a throttle valve is controlled by an actuator. It is intended.

<Prior Art> An internal combustion engine (engine) obtains an output using thermal energy obtained by burning a mixture of air and fuel. In this engine, the amount of air is adjusted by changing the opening of the throttle valve by the driver's accelerator operation, and the amount of fuel is controlled so as to achieve the air-fuel ratio set for this amount of air. Output.

The opening and closing of the throttle valve is controlled in conjunction with the amount of depression of the accelerator pedal (accelerator opening). Throttle valves are driven by various methods, but the method of opening and closing the throttle valve (DBW: Drive By Wire) by using an actuator to electrically open and close the throttle valve is often adopted. It has become to.

In the DBW method, the actuator is an ECU (Electronic Con
trol unit). Accelerator opening information is detected by an accelerator position sensor, and the detected value is input to the ECU. The ECU calculates the opening degree and the opening speed of the throttle valve based on the information of the engine condition and the detection value of the accelerator position sensor, and outputs a drive command to the actuator to open the throttle valve in a predetermined state. Thus, the throttle valve can be opened and closed in conjunction with the accelerator opening without mechanically connecting the accelerator pedal and the throttle valve.

By the way, gasoline is generally used as a fuel for an engine of an automobile, but recently, fuel containing alcohol has been used due to concerns about supply of crude oil.
Vehicles that use fuel containing alcohol (FFV: Flexible Fu
The elvehicle engine can be operated using gasoline, methanol, or any mixture of these fuels.

In recent years, the opening and closing of FFV engine throttle valves has been
This is being done in a system.

<Problems to be Solved by the Invention> Since the compression ratio of the engine is mechanically designed to be constant, the output of the engine increases as the FFV engine uses a fuel with a higher mixing ratio of alcohol (methanol) with a high octane number. I do. For this reason, when the driver operates the accelerator at the same accelerator opening speed, there is a difference in the time to reach the predetermined vehicle speed between when the amount of methanol is large in the fuel and when the amount of gazoline is large, and depending on the mixing ratio of methanol in the fuel. Driving sensations such as acceleration were different.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of controlling a throttle valve that can maintain a constant acceleration state with respect to an accelerator opening speed regardless of the type of fuel.

<Means for Solving the Problems> The throttle valve control method of the present invention for achieving the above object is a method for controlling an opening speed of a throttle valve by an actuator in conjunction with an accelerator opening speed. Using heterogeneous fuel in which fuel is mixed, detecting the depression speed of an accelerator pedal and the mixing ratio of the heterogeneous fuel, controlling the actuator according to the mixing ratio of the heterogeneous fuel supplied to an engine, The opening speed of the throttle valve is adjusted so that the engine output with respect to the depression speed of the accelerator pedal is kept constant irrespective of the change in the mixing ratio.

<Effect> By controlling the actuator in accordance with the mixing ratio of the heterogeneous mixed fuel and adjusting the opening speed of the throttle valve so as to keep the engine output constant with respect to the accelerator pedal depressing speed regardless of the change in the mixing ratio, the heterogeneous mixed fuel is controlled. The difference in the output generation state (difference in output change characteristic) at the same accelerator opening speed when the mixing ratio of the output changes is eliminated.

<Embodiment> FIG. 1 shows a cross section of an essential part of an engine for implementing a throttle valve control method according to an embodiment of the present invention.

A cylinder head 3 is attached to a cylinder block 2 provided with a piston 1. The cylinder head 3 is provided with an intake port 5 and an exhaust port 6 that communicate with a combustion chamber 4. An intake pipe 7 and an exhaust pipe 8 are provided in the cylinder head 3, and the intake pipe 7 and the exhaust pipe 8 are respectively connected to the intake port 5.
And the exhaust port 6.

The cylinder head 3 is provided with an intake valve 9 for opening and closing the intake port 5 and an exhaust valve 10 for opening and closing the exhaust port 6. The cylinder head 3 is provided with an ignition plug 11 facing the combustion chamber 4. The intake pipe 7 is provided with an injector 12 for supplying fuel into the intake pipe 7. As the fuel, a heterogeneous fuel in which different types of fuel are mixed, that is, gasoline and alcohol are mixed is used. A supply path 13 for sending a heterogeneous mixed fuel (fuel) from a fuel source to the injector 12 is provided with a mixing ratio sensor 14 for detecting a mixing ratio (mixing ratio) of gasoline and alcohol in the fuel.

A valve body 15 is connected to the intake pipe 7, and a throttle valve 16 is provided on the valve body 15 so as to be openable and closable.
The throttle valve 16 is driven to open and close by a throttle motor 17 (throttle opening). On the other hand, the accelerator pedal 18 is provided with an accelerator pedal sensor 19, and the accelerator pedal sensor 19 detects the amount of depression of the accelerator pedal 18 (accelerator opening degree θ).

In FIG. 1, reference numeral 20 denotes an ECU. The ECU 20 receives the values detected by the mixture ratio sensor 14 and the accelerator pedal sensor 19,
Then, an operation command is output to the ignition plug 11, the injector 12, and the throttle motor 17. The ECU 20 calculates the accelerator opening speed (dθ / dt: t is time) based on the value detected by the accelerator pedal sensor 19.

In the engine having the above configuration, the throttle motor 17 is driven in conjunction with the depression of the accelerator pedal 18, and the throttle valve 16 is opened according to the accelerator opening θ. The intake air according to the opening degree of the throttle valve 16 is mixed with the fuel injected by the injector 12 to form an air-fuel mixture, and the air-fuel mixture flows into the combustion chamber 4 from the intake pipe 7 and the intake port 5. The air-fuel mixture is compressed and expanded (exploded) in the combustion chamber 4 and then discharged from the exhaust port 6 to the exhaust pipe 8. This engine is operated by gasoline, alcohol (methanol) and a mixed fuel thereof.

A control method of the throttle valve 16 will be described with reference to FIGS.

FIG. 2 shows the throttle opening speed (d
/ dt) and the accelerator opening speed (dθ / dt). The unit of each opening speed is rad / sec.

In the figure, the solid line shows the state of gasoline 100%, the one-dot chain line shows the state of methanol 100%, and the two-dot chain line shows the state of gasoline 50% -methanol 50%. When the accelerator opening speed is the same, compared to the throttle opening speed when gasoline is 100%,
The opening speed of the throttle valve 16 when methanol is 100% is set to be slow, and the difference increases as the accelerator opening increases. Also, 50% gasoline,
In the case of 50% methanol, the opening speed of the throttle valve 16 is set at an intermediate value.

FIG. 3 shows the relationship between the throttle opening and the time t, and FIG. 4 shows the relationship between the vehicle speed and the time t at the same time as in FIG.

As shown in FIG. 4, when the throttle valve 16 is fully opened, when the gasoline is 100%, the torque changes as shown by the solid line in the figure, and when the alcohol is 100%, the torque changes as shown by the dashed line in the figure. The operation of the pedal 18 causes a difference in the rising state of the vehicle speed. Therefore, by changing the opening speed of the throttle valve 16 with respect to the accelerator opening speed in accordance with the fuel as shown in FIG. 2, if the mixing ratio of methanol in the fuel increases, the opening speed of the throttle valve 16 becomes slower than in the case of gasoline. (Shown by a dotted line in FIG. 3). This allows
As shown by the dotted line in FIG. 4, even when the mixing ratio of methanol increases, the rising state of the vehicle speed is substantially the same as when gasoline is used as fuel.

The mixing ratio sensor 14 detects the mixing ratio of fuel (the ratio of gasoline and methanol), and the detected value is input to the ECU 20. The accelerator opening θ is input to the ECU 20, the opening speed of the throttle valve 16 is calculated according to the accelerator opening speed and the fuel condition, and the throttle motor 17 is operated so that the throttle valve 16 is driven to open at a predetermined opening speed. A command is output from the ECU 20.

The control situation by the ECU 20 will be described based on the flowchart shown in FIG.

Detection value of accelerator pedal sensor 19 (accelerator opening θ)
Is input to the ECU 20, and the accelerator opening speed dθ / dt is read based on the accelerator opening θ. In addition, mixing ratio sensor 1
The detected value of 4 is input to the ECU 20, and the state of the fuel is read. The opening speed dθ / dt of the throttle valve 16 is determined by the map shown in FIG. 2 based on the fuel condition (mixing ratio of methanol) and the accelerator opening speed dθ / dt. An operation command is output to the throttle motor 17 so that the throttle valve 16 is driven to open at the determined opening speed dθ / dt, and the throttle valve 16 is driven to open at a suitably low speed according to the mixing ratio of methanol in the fuel. Is done.

In other words, the throttle motor 17 as an actuator is controlled in accordance with the mixing ratio of the heterogeneous mixed fuel supplied to the engine, and the throttle valve 16 is controlled so as to keep the engine output constant with respect to the depression speed of the accelerator pedal 18 regardless of the change in the mixing ratio. The opening speed is adjusted.

As a result, the opening speed d of the throttle valve 16 increases as the mixing ratio of methanol increases depending on the fuel condition.
By decreasing / dt, the rise in vehicle speed when using methanol, which achieves high output, can be made substantially the same as when gasoline is used as fuel.

According to the control method of the throttle valve 16 described above, since the throttle opening speed of the throttle valve 16 when using methanol as fuel is made slower than the opening speed of the throttle valve 16 when using gasoline as fuel, high output The rising state of vehicle speed when methanol is used as fuel can be made substantially the same as the state when gasoline is used as fuel.
For this reason, it is possible to eliminate the difference between the state of output generation at the same accelerator opening when using methanol as fuel and when using gasoline as fuel.

In the above-described method of controlling the throttle valve, the opening speed of the throttle valve when using alcohol, which achieves a high output, is made slower than the opening speed of the throttle valve when using gasoline as fuel. The output generation time is delayed when the engine is turned on, so it is possible to eliminate the difference in the engine output generation state at the same accelerator opening speed when using alcohol as fuel and when using gasoline as fuel. Regardless, the acceleration state with respect to the accelerator opening speed can be kept constant (the output change characteristic can be kept substantially constant).

<Effect of the Invention> The depression speed of the accelerator pedal is detected regardless of the change in the mixture ratio by detecting the depression speed of the accelerator pedal and the mixture ratio of the heterogeneous fuel mixture, and controlling the actuator in accordance with the mixture ratio of the heterogeneous mixture fuel supplied to the engine. The opening speed of the throttle valve is adjusted so as to keep the engine output constant with respect to the engine speed, so that the engine output change characteristics at the same accelerator opening speed when the mixing ratio of the heterogeneous fuel mixture changes are kept almost constant. Can be. As a result, it is possible to eliminate the difference in the state of output generation with respect to the accelerator pedal depressing speed due to the difference in fuel, eliminate the acceleration shock associated with engine output changes, and obtain a constant operation feeling regardless of the fuel mixing ratio. A high-value engine can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part of an engine for implementing a method of controlling a throttle valve according to one embodiment of the present invention, FIG. 2 is a graph showing a relationship between an opening speed of a throttle valve and an accelerator opening speed, and FIG. FIG. 4 is a graph showing the relationship between the throttle opening and time, FIG. 4 is a graph showing the relationship between vehicle speed and time, and FIG. 5 is a control flowchart by the ECU. In the drawing, 4 is a combustion chamber, 7 is an intake pipe, 9 is an intake valve, 12 is an injector, 14 is a mixing ratio sensor, 16 is a throttle valve, 17 is a throttle motor, 18 is an accelerator pedal, 19 is an accelerator pedal sensor, 20 Is an ECU.

Claims (1)

(57) [Claims] In an internal combustion engine in which an opening speed of a throttle valve is controlled by an actuator in conjunction with an opening speed of an accelerator, different types of mixed fuels in which different types of fuels are mixed are used, and the accelerator pedal depression speed and Detecting the mixing ratio of the heterogeneous fuel mixture and controlling the actuator in accordance with the mixing ratio of the heterogeneous fuel mixture supplied to the engine to keep the engine output constant with respect to the accelerator pedal depression speed regardless of the change in the mixing ratio. A method for controlling a throttle valve, comprising adjusting an opening speed of the throttle valve so as to maintain the opening speed.