Interrelated power delivery controls – including engine control – Transmission control – Engine controlled by transmission
Reexamination Certificate
2000-12-08
2002-08-06
Wright, Dirk (Department: 3681)
Interrelated power delivery controls, including engine control
Transmission control
Engine controlled by transmission
C477S106000, C701S053000
Reexamination Certificate
active
06428448
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a constant-speed running controller for vehicle equipped with an engine.
2. Description of the Related Art
Recently, it has become known to provide a vehicle equipped with an electronic throttle controller referred to as DBW (drive by wire) for electrically controlling the opening of a throttle valve without mechanically associating the opening of the throttle valve with an accelerator pedal operation. In the electronic throttle controller, a target opening is set for the throttle valve based on vehicle driving conditions, such as the amount of accelerator pedal operation, and the throttle valve is electrically controlled through an actuator to provide the target opening.
A vehicle equipped with the electronic throttle controller has the throttle opening characteristic stored as a data table indicative of a throttle opening for the amount of accelerator pedal operation. Also, the throttle opening characteristics are provided individually for respective operating conditions such as an acceleration to select a throttle opening characteristic in accordance with actually detected operating conditions for use in controlling the throttle.
When a vehicle equipped with such an electronic throttle controller has a constant-speed running controller for operating the vehicle at a constant speed, the throttle valve opening is controlled in accordance with a change in running load such as a slope to maintain the constant-speed running or operation even if the accelerator pedal is not actuated during the constant-speed running control. Also, when the driver's intention for acceleration is detected from actuation of accelerator pedal during the constant-speed running control, a temporary transition to an accelerating operation is made.
As the control for constant-speed running, it is known that there are apparatuses which employ a method of controlling the opening of a throttle valve in accordance with the vehicle speed or a method of controlling the transmission stage (including a lock-up clutch) of an automatic transmission together with the opening of a throttle valve. Also, Laid-open Japanese Patent Application No. 10-306871 discloses a constant-speed running controller which calculates a pseudo-acceleration opening in accordance with a difference between an actual vehicle speed and a target speed to control the opening of a throttle valve in accordance with the pseudo-acceleration opening in a constant-speed running mode.
FIG. 1
shows an example of changes in vehicle speed, running load, throttle valve opening, amount of accelerator pedal operation, and transmission stage of an automatic transmission in the constant-speed running mode, when using a constant-speed running controller for controlling the throttle valve opening in accordance with the vehicle speed. In
FIG. 1
, when the running load increases due to a slope in a constant-speed running mode, the vehicle speed decreases from a target speed (broken line), and the throttle valve opening is controlled to increase from a target opening. This causes the speed to increase back to the target speed. Conversely, when the running load decreases, the vehicle speed increases from the target speed, and the throttle valve opening is controlled to decrease from the target opening in response thereto. This causes the speed to decrease back to the target speed. The transmission stage of the automatic transmission is maintained, for example, at a fourth speed. When the accelerator pedal is depressed by the driver for acceleration at a time T in the constant-speed running mode, if the amount of accelerator pedal depression (accelerating pedal opening) exceeds the target opening of the throttle valve opening, the throttle valve opening is controlled to increase from the target opening in response to the operation of the accelerator pedal before proceeding to an accelerating operation.
However, in the conventional constant-speed running controller, since the actual opening of the throttle valve does not change until the accelerating pedal operation exceeds the target opening of the throttle valve opening even if the accelerator pedal is depressed by the driver for acceleration at the time T in the constant-speed running mode, a so-called dead zone occurs, resulting in a problem that good drivability is not provided.
FIG. 2
shows an example of changes in vehicle speed, running load, throttle valve opening, amount of accelerator pedal operation, and transmission stage of an automatic transmission in the constant-speed running mode, when using a constant-speed running controller for controlling the transmission stage of an automatic transmission together with the throttle valve opening. In
FIG. 2
, when the running load increases due to a slope in the constant-speed running mode, the vehicle speed decreases from a target speed (broken line), and the throttle valve opening is controlled to increase from a target opening in response thereto. The automatic transmission is also shifted down due to the increased throttle valve opening. This causes the speed to increase back to the target speed. Conversely, when the running load decreases, the running speed increases from the target speed, the throttle valve opening is controlled to decrease from the target opening in response thereto, and the automatic transmission is shifted up due to the decreased throttle valve opening. This causes the speed to decrease back to the target speed. When the accelerator pedal is operated by the driver for acceleration at a time T in the constant-speed running mode, the throttle valve opening is immediately controlled to increase from the target opening during the constant speed running in accordance with the amount of accelerator pedal operation to proceed to an accelerating operation.
The constant-speed running controller shown in
FIG. 2
can immediately proceed to the accelerating operation even if the accelerator pedal is operated for acceleration in the constant-speed running mode. However, since the target opening of the throttle valve is set higher than a throttle valve opening corresponding to the degree of accelerator pedal operation of zero, the transmission stage of the automatic transmission shifts down to cause shift hunting from a fourth speed to a second speed as shown in FIG.
2
. Otherwise, the lock-up of the automatic transmission turns off in an unexpected situation, causing another problem of vehicle shock.
FIG. 3
shows an example of changes in vehicle speed, running load during a constant-speed running mode period (in a period in which a cruise switch is on), throttle valve opening, accelerator pedal operation, pseudo-throttle valve opening, and transmission stage of an automatic transmission when using a constant-speed running controller shown in the above-mentioned Laid-open Japanese Patent Application No. 10-306871.
Since the constant speed running controller calculates a pseudo-acceleration opening in accordance with a difference between an actual vehicle speed and a target speed to control the throttle valve opening in accordance with the pseudo-acceleration opening in the constant-speed running mode, as described above, there is a problem that the throttle valve opening is discontinuous immediately after starting or ending the constant-speed running mode so as to cause an unexpected shift-up or shift-down of the automatic transmission. There is also another problem that since the throttle valve opening is eventually controlled in accordance with the difference in vehicle speed, even if the running load increases due to a slope in the constant-speed running mode, the automatic transmission has a delayed downshift, causing the vehicle speed to substantially decrease from the target vehicle speed.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a constant-speed running controller for a vehicle which is capable of improving the follow-up characteristic to a target vehicle speed and the drivability for operation of t
Konno Kazuyuki
Nakauchi Norio
Saito Yoshiharu
Shimada Takamichi
Arent Fox Kintner & Plotkin & Kahn, PLLC
Lewis Tisha D.
Wright Dirk
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