JP2003161188A - Method for operating by lean operation internal combustion engine operated by otto principle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for operating by lean operation an internal combustion engine operated by the OTTO principle in which sufficient negative pressure is securely supplied in an intake pipe in order to amplify a braking device, without causing additional fuel consumption or providing a supplementary sensor for monitoring the negative pressure in the intake pipe. <P>SOLUTION: The method for operating by lean operation an internal combustion engine operated by the OTTO principle includes the step of measuring the rotational speed of the internal combustion engine; the step of measuring the position of an accelerator pedal; the step of detecting operation of a brake pedal; and the step of operating the internal combustion engine when the rotational speed of the engine is beyond the idling range, when the accelerator pedal is at a neutral position, and when the brake pedal is operated, at a theoretical air fuel ratio or under such a condition that coasting is intercepted or a throttle valve is closed to the minimum required value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating an internal combustion engine that operates according to the Otto principle in lean operation.

[0002]

BACKGROUND OF THE INVENTION In motor vehicles, internal combustion engines operating according to the Otto principle generally have a theoretical air / fuel mixture (λ =
It is operated in 1). In this operating method, the amount of air taken in by the combustion chamber is controlled by the throttle valve in the intake pipe. Therefore, in most operating conditions of this internal combustion engine, a high negative pressure is applied to the intake pipe.

In order to improve efficiency, internal combustion engines which operate according to the Otto principle are known to operate in the partial load range, so-called lean operation (λ> 1). In this operating method, the throttle valve loss in the intake pipe is
It is significantly smaller than in the usual Otto principle. This effect improves the efficiency of the internal combustion engine along with other effects, especially in partial load operation.

Independently of the operating mode of the internal combustion engine, braking force amplification takes place in modern vehicles, in which case the necessary auxiliary energy is obtained from the negative pressure in the intake pipe of the internal combustion engine. As described above, since a sufficient negative pressure is not applied to the intake pipe during lean operation, it is not possible to guarantee reliable braking force amplification in this operating state.
In order to ensure sufficient braking force amplification, operate the internal combustion engine of a vehicle that runs lean according to the Otto principle so that the internal combustion engine is driven in theoretical operation whenever braking force amplification is required. Is known.
As a result, a desired negative pressure is formed in the intake pipe. For this reason, in the past, an expensive sensor had to be provided in order to control the negative pressure in the intake pipe.

[0005]

Sufficient in the intake pipe to amplify the brake system without producing additional fuel consumption and without providing an additional sensor for monitoring the negative pressure in the intake pipe. It is an object of the present invention to provide a method of operating an internal combustion engine that operates according to the Otto principle in lean operation, which reliably supplies a negative pressure.

[0006]

According to the present invention, the rotational speed of an internal combustion engine is measured, the accelerator pedal position is measured, the operation of a brake pedal is detected, and the rotational speed of the internal combustion engine is idling. When above range, when the accelerator pedal is in the neutral position and when the brake pedal is operated, the throttle valve is closed to the minimum required value, or the internal combustion engine shuts off at stoichiometry or coasting. It is solved by a method of operating an internal combustion engine which operates according to the Otto principle in a lean operation.

By using the method according to the invention,
It is possible to ensure that sufficient negative pressure is present in the intake pipe of the internal combustion engine whenever the brake is actuated, and thus when brake amplification is required.
Furthermore, in modern internal combustion engines, the measurement of the rotational speed of the internal combustion engine is performed anyway, so that the method according to the invention does not require additional switches or sensors. The same applies to the device for measuring the accelerator pedal position and the device for detecting the operation of the brake pedal. These devices are in any case present in conventional motor vehicles.

According to the present invention, the need to assist the braking force is detected and the throttle valve of the internal combustion engine is detected by combining the measured state of the internal combustion engine or its rotational speed and accelerator pedal position with the operation of the brake pedal. Is operated such that theoretical operation is performed, and as a result, a sufficiently large negative pressure is applied to the intake pipe. The throttle effect of the throttle valve in the intake pipe increases the engine braking effect of the internal combustion engine, which effectively works for deceleration of the vehicle.

In one embodiment of the method according to the invention:
The theoretical mode of operation of an internal combustion engine may be designed to be monitored by measuring and validating the air mass flow drawn by the internal combustion engine. This monitoring improves the reliability of the method according to the invention and can be done at no additional cost by the proper use of any existing equipment, eg air mass flow sensors.

In another supplementary aspect of the method according to the invention, the internal combustion engine is operated in a lean mode after the brake pedal has been operated, which reduces the fuel consumption rate of the internal combustion engine.

The fuel consumption rate of the internal combustion engine can be further reduced when the internal combustion engine is operated in a lean operation after the rotational speed limit for coasting shutoff of the internal combustion engine is exceeded.

In order to increase the certainty of the method according to the invention, the actuation of the brake pedal may furthermore be designed to be detected by two redundant switches. Other advantages and advantageous embodiments of the invention are apparent from the drawings and the description below.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a flow chart of an embodiment of a method for operating a lean internal combustion engine operating according to the invention according to the invention.

In order to amplify the braking system of a motor vehicle,
In an automobile having an Otto engine, a negative pressure is usually formed in the intake pipe of the internal combustion engine. In an internal combustion engine that operates on the Otto principle, so-called lean operation (λ>
In 1), since a sufficiently large negative pressure is not applied to the intake pipe, reliable braking amplification by this negative pressure is not sufficiently possible in this operating system. In theoretical operation of an internal combustion engine (λ = 1), the throttle valve in the intake pipe is
In the air flow passage, the internal combustion engine is swirled to such an extent that only a relatively small amount of air can be taken in. As a result, the pressure behind the throttle valve in the intake pipe drops significantly. In some internal combustion engines, pressure drops below 0.8 bar may be measured in the intake pipe when the throttle valve is closed. Here, in order to make this negative pressure available whenever the vehicle is to be braked, the invention measures the rotational speed of the internal combustion engine, the accelerator pedal position, and the brake pedal Whether or not it is operated is detected.

When the rotational speed of the internal combustion engine is above the idling range, the accelerator pedal is in the neutral position, and the brake pedal is operated, there is a situation in which the vehicle must be braked, and thus the intake pipe Brake operation can be assisted by negative pressure as desired. Therefore, according to the method of the present invention, when these three conditions are present, the throttle device is closed to the minimum required value, or the internal combustion engine is operated at stoichiometry or with coasting shut off, which causes The desired negative pressure is created. As a result, brake amplification is available and yet available whenever the driver of the vehicle desires to decelerate the vehicle. A valve control of a gas exchange valve with a variable valve lift may be used as the throttle device.

When one or more of the above three conditions are not met, the driver of the vehicle does not want to decelerate the vehicle, so no braking force assistance is required. Therefore, the internal combustion engine can be continuously operated in lean operation.

As an alternative, the method according to the invention can also be monitored by additionally measuring the air mass flow drawn by the internal combustion engine and performing a plausibility check. As a result, it is possible to detect the error function of the sensor, actuator or control device of the internal combustion engine, and switch to a so-called emergency operation program.

Since the method according to the invention can be superposed on the known method of an internal combustion engine operating according to the Otto principle, the known operating method of the internal combustion engine itself operating according to the Otto principle remains unchanged. It can be used as it is and can be improved by the method of the present invention.

[Brief description of drawings]

1 is a flow chart of an embodiment of a method for operating a lean internal combustion engine operating according to the Otto principle according to the invention.

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Claims (9)

[Claims] 1. A step of measuring a rotation speed of an internal combustion engine, a step of measuring an accelerator pedal position, a step of detecting an operation of a brake pedal, and a step of detecting a rotation speed of the internal combustion engine when the rotation speed of the internal combustion engine is above an idling range. Operating the internal combustion engine when the accelerator pedal is in the neutral position and when the brake pedal is operated, at stoichiometric air-fuel ratio, or by shutting off coasting, or the throttle valve is closed to the minimum required value; A method for operating a lean internal combustion engine that operates according to the Otto principle. 2. The method according to claim 1, characterized in that the theoretical operating mode of the internal combustion engine is monitored by measuring and validating the mass air flow drawn by the internal combustion engine. 3. The method according to claim 1, wherein the internal combustion engine is operated in a lean operation after the operation of the brake pedal is finished. 4. The method as claimed in claim 1, wherein the internal combustion engine is operated in a lean mode after the rotational speed limit for coasting interruption has been exceeded. 5. The method according to claim 1, wherein the actuation of the brake pedal is detected by two redundant switches. 6. A microprocessor, which is suitable for carrying out the method according to claim 1. 7. A computer suitable for carrying out the method according to claim 1.
program. 8. The computer program according to claim 7, which is stored in a storage medium. 9. A control device for an internal combustion engine operating according to the Otto principle, which is suitable for carrying out the method according to claim 1.