Internal-combustion engines – Engine speed regulator – Open loop condition responsive
Reexamination Certificate
1999-08-05
2001-08-21
Solis, Erick (Department: 3747)
Internal-combustion engines
Engine speed regulator
Open loop condition responsive
C123S399000
Reexamination Certificate
active
06276331
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an internal combustion engine equipped with an electronic controlled throttle system for operating a throttle valve equipped in an intake system of the engine to be opened and closed by an actuator to a target position, and more specifically, to a fail-safe control technique in an engine comprising two accelerator position sensors and two throttle position sensors or comprising at least two throttle position sensors, wherein said fail-safe control is performed in case one sensor out of said two sensors fails to operate.
(2) Related Art of the Invention
Conventionally, an electronic controlled throttle system is known where the opening (position) of the throttle valve is electronically controlled based on the accelerator position (step-in quantity of the accelerator pedal) and the engine rotation speed and the like, so as to gain a target air quantity (Japanese Unexamined Patent Publication No. 7-180570).
Of such known electronic controlled throttle systems, the ones that are not equipped with a limp-home structure for mechanically linking the throttle valve by means of the accelerator operation through a wire and the like (full electronic controlled throttle system) are applied, for example, with the following system in case the drive system fails to operate. The system includes two accelerator position sensors and two throttle position sensors, and as for the accelerator position or opening, the smaller value of the two detection values is selected (so as to prevent excessive output), and as for the throttle valve position or opening, the value detected by the main throttle position sensor is used, wherein in some cases, the greater value of the two detection values is selected (the greater value is selected and the value is corrected to a smaller value by a feedback control, thereby preventing excessive output).
According to the fail-safe method in such full electronic controlled throttle system, when one of the two sensors fails to operate (hereinafter called single failure) and the control is switched to utilize only the value detected by the remaining working single sensor, the promptness of failure detection provided by equipping double sensors is lost. Therefore, when the remaining working sensor also breaks down, the change in engine output will become large for a period of time until the failure is judged to have occurred. For safety, such trouble must be prevented.
The present invention is aimed at solving such problem of the conventional system mentioned above. The object of the present invention is to enable the vehicle to travel at the minimum speed necessary (limp-home) while preventing the excessive increase of the engine output, when single failure occurs to either of the two accelerator position sensors or the two throttle position sensors.
Further object of the present invention is to prevent the excessive increase of the engine output by limiting either the absolute value and/or the increase rate of the output.
Another object of the present invention is to enable the vehicle to travel at a speed corresponding to need while preventing the excessive increase of the engine output, when single failure occurs to one of the two throttle position sensors.
Another object of the present invention is to prevent the excessive increase of the engine output more securely during single failure of the throttle position sensor.
Further object of the present invention is to prevent the stalling of the vehicle caused by unnecessary decrease of the engine output during single failure of the throttle position sensor.
SUMMARY OF THE INVENTION
In order to realize the above objects, a first fail-safe control method of an internal combustion engine with an electronic controlled throttle system according to the present invention comprises the steps of:
setting a target position of a throttle valve equipped in an intake system of the engine according to engine operating conditions including an accelerator position detected by one accelerator position sensor selected from two accelerator position sensors equipped to the engine;
operating the throttle valve to open and close by an actuator, so that the position of the throttle valve detected by one throttle position sensor selected from two throttle position sensors equipped to the engine reaches the target position; and
providing a limit to the increase in accelerator opening for the output characteristics of the selected accelerator position sensor, when one sensor out of the two accelerator position sensors or the two throttle position sensors fails to operate.
Further, a first fail-safe control apparatus of an internal combustion engine with an electronic controlled throttle system according to the present invention comprises:
two accelerator position sensors for detecting an accelerator position;
a target position setting device for setting a target position of a throttle valve equipped in an intake system of the engine according to engine operating conditions including the accelerator position detected by a selected one accelerator position sensor out of the two accelerator position sensors;
two throttle position sensors for detecting a position of the throttle valve;
a throttle valve driving device for opening and closing said throttle valve by an actuator, so that the position of the throttle valve detected by one throttle position sensor selected from the two throttle position sensors reaches the target position; and
an output characteristics limiting device for providing a limit to the increase in accelerator opening for the output characteristics of the selected accelerator position sensor, when one sensor out of the two accelerator position sensors or the two throttle position sensors fails to operate.
According to the first fail-safe control method or apparatus of an internal combustion engine with an electronic controlled throttle system of the present invention, when one sensor out of the two accelerator position sensors or the two throttle position sensors fails to operate, the detection value of the remaining sensor is utilized. When doing so, a limit to the increase in accelerator opening is provided for the output characteristics of the selected accelerator position sensor, so the increase in the throttle opening controlled based on the limited output characteristics will also be limited, thereby enabling the vehicle to travel at the minimum speed necessary (limp-home) while preventing the excessive increase in the engine output.
Further, the limit to the increase in accelerator opening may include a function to limit the absolute value of the accelerator position by an upper limit value.
This enables the absolute value of the accelerator position to be limited by an upper limit value, which limits the upper limit of the throttle position, and a limp-home control may be performed where the increase in the absolute speed is restrained.
Even further, the limit to the increase in accelerator opening may include a function to limit the increase change rate of the accelerator position by an upper limit change rate.
This enables the increase change rate of the accelerator position to be limited by an upper limit change rate, whereby the increase change rate of the throttle position is limited, and a limp-home control may be performed where rapid acceleration is restrained.
Even further, the limit to the increase in accelerator opening may include a function to limit the absolute value of the accelerator position by an upper limit value and a function to limit the increase change rate of the accelerator position by an upper limit change rate, and the smaller value between the accelerator position being limited by the upper limit value and the accelerator position being limited by the upper limit change rate may be selected.
Accordingly, by selecting through the output characteristics limiting device the smaller value out of the accelerator position limited of its absolute value by an upper limit value, and the accelerator position limit
Iriyama Masahiro
Machida Kenichi
Nozaki Mikio
McDermott & Will & Emery
Solis Erick
Unisia Jecs Corporation
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