Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
2000-05-12
2001-10-30
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C701S055000, C477S042000, C477S097000
Reexamination Certificate
active
06311118
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a vehicle speed control system, more particularly to a vehicle speed control system equipped with a cruise controller and a CVT (Continuously Variable Transmission).
2. Description of the Related Art
Japanese Laid-open Patent Application No. Hei 10 (1998)-29448 teaches a cruise controller for a vehicle equipped with a CVT. This cruise controller has a followup operation to follow up another vehicle running ahead of the subject vehicle. In this prior art system, when the followup operation is in progress, the ratio (speed ratio) of the CVT is controlled at a fixed ratio and it is determined whether required torque is available. If the required torque is not available, the air/fuel ratio to be supplied to the engine is enriched, thereby reducing the engine speed fluctuation and preventing wandering of the engine speed from happening.
Vehicles equipped with a CVT can act quickly in response to the change of throttle opening operated by the vehicle operator, thereby enhancing the acceleration performance. However, this is disadvantageous when the vehicle conducts cruise control which requires no rapid acceleration. Specifically, when the vehicle under cruise control travels on a road whose grade varies, if the throttle actuator operates to open the throttle valve temporarily so as to maintain a desired vehicle speed, the CVT controller responds too quickly, thereby resulting in the engine speed changing and sometimes making the vehicle operator feel uneasy.
This will be explained with reference to FIG.
9
. Assume that the gradient of the road (on which the vehicle climbs) changes as illustrated in the figure by solid line. As the vehicle advances the upsloping road, the vehicle speed drops and as a result, the cruise controller operates the throttle actuator to open the throttle valve so as to raise the vehicle speed toward a desired speed. Parallel to this, the CVT controller controls the ratio (speed ratio) of the CVT to the low side.
As the vehicle speed approaches the desired speed, the cruise controller returns the throttle valve to the closing direction and in response thereto, the CVT controller controls the ratio in the high side to a value, which deviates in the low side by an amount &agr;, for example. However, the CVT controller responds to the throttle actuator operation to open the throttle valve so as to correct the vehicle speed drop, it will further control the ratio to the low side by an additional amount &bgr;, for example. In the upslope change illustrated, it suffices if the ratio is controlled only by the amount &agr;. The unnecessary amount &bgr; will raise the engine speed, making the vehicle operator feel uneasy.
Although the earlier prior art mentioned above teaches cruise controller for vehicles equipped with a CVT, it does not go beyond simple measures such as fixing the speed ratio when the followup operation is in progress and is therefore incapable of offering a solution to the issues discussed above.
SUMMARY OF THE INVENTION
An object of this invention is to eliminate the drawbacks of the prior art by providing a vehicle speed control system that, when applied to a vehicle equipped with a CVT connected to the vehicle engine for transmitting the engine output torque while continuously varying the speed ratio of the CVT, can reduce the engine speed fluctuation when cruise control is effected so as to control the vehicle speed toward a desired speed in response to the instruction to cruise control inputted by the vehicle operator, thereby preventing the vehicle operator to feel uneasy.
For realizing this object, the present invention provides a system for controlling a speed of a vehicle having a continuously variable transmission which transmits output torque generated by an internal combustion engine mounted on the vehicle to drive wheels of the vehicle, and a cruise controller which controls the speed of the vehicle to a desired speed in response to an instruction to cruise control inputted by a vehicle operator, comprising: operating condition detecting means for detecting operating conditions of the engine and the vehicle including at least an opening of a throttle valve and the speed of the vehicle; throttle opening smoothing means for smoothing the detected opening of the throttle valve; and shift controlling means for controlling a speed ratio of the continuously variable transmission based at least on the detected opening of the throttle valve and the detected speed of the vehicle; wherein the shift controlling means controlling the speed ratio of the continuously variable transmission based at least on the smoothed opening of the throttle valve and the detected speed of the vehicle, when the instruction to cruise control is inputted.
REFERENCES:
patent: 4933859 (1990-06-01), Tsuyama et al.
patent: 4936403 (1990-06-01), Morimoto
patent: 4967357 (1990-10-01), Mimura et al.
patent: 5317937 (1994-06-01), Yoshizawa et al.
patent: 5611748 (1997-03-01), Kashiwabara
patent: 6066070 (2000-05-01), Ito et al.
patent: 5-71625 (1993-03-01), None
patent: 9-207616 (1997-08-01), None
patent: 10-29448 (1998-02-01), None
Ito Akira
Kotani Hideaki
Sato Hiroshi
Sen Naoto
Arent Fox Kintner & Plotkin & Kahn, PLLC
Honda Giken Kogyo Kabushiki Kaisha
Zanelli Michael J.
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