Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
1997-12-17
2001-01-30
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S070000, C701S200000, C701S096000, C701S053000, C701S095000, C180S179000, C180S170000
Reexamination Certificate
active
06182000
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
This invention is directed to a control device for an automatic transmission, which has plural and non-continuous gear stages, is controlled based on the information regarding the road condition of the route that the vehicle follows. This information is output by a route information detection device.
2. Related Art
Generally, the gear stage of an automatic transmission for a vehicle is automatically controlled by the driving condition of the vehicle, which is detected by various sensors. Although if sensors are used to detect the vehicle driving condition, they can only detect the change of the vehicle driving condition when the vehicle encounters an actual change in road conditions. So, if sensors are used, the driving force is changed by shifting the gear stages after detection of an actual change in the driving condition, which sometimes reduces the drivability and performance of the vehicle. Recently, it has become possible for a route information detection system, for example, a navigation system, to detect in advance information regarding the road condition, on which the vehicle travels, and this information is used to control shifting of the gear stages of an automatic transmission before the road conditions actually change. An example of a vehicle control system is disclosed in Japanese Patent Laid Open Publication No. HEI 7-306998.
In the above mentioned patent, the vehicle control system has a digital map, which stores information on a road map, navigation system, which calculates location of the vehicle on the map, a wheel sensor, which detects the vehicle speed, a predict system, which predicts the route that the vehicle will follow, a driving skills determining system, which determine the driver's skills, an appropriate speed calculating system, which calculates an appropriate speed for the driver based on his driving skills, a comparison system, which compares the calculated appropriate speed and the actual running speed, a vehicle acceleration calculation system that calculates the acceleration that the vehicle should take to make the vehicle travel at said appropriate speed by taking into account the information from the comparison system, continuously variable transmission (CVT), and a transmission control system, which controls a speed ratio of the CVT based on the calculated vehicle acceleration. The above mentioned system takes the following steps when the vehicle road conditions where require deceleration, for example, to enable to go through a curve safely. First of all, the vehicle control system judges whether the driver will be able to through the curve smoothly through the curve at the present speed, the appropriate speed for going smoothly through the curve is calculated. Second of all, the speed plan is determined to decrease the vehicle speed from the present speed to the appropriate speed for going through the curve, and the target speed is determined. Taking into consideration the driver's skills, the vehicle deceleration is calculated to make the present vehicle speed the target speed. The maximum of this deceleration is set so the driver may not feel the deceleration. Consequently, without making the passengers uncomfortable, the vehicle decreases its speed to the appropriate speed for going through the curve before the vehicle reaches the curve, thereby enabling the vehicle to go smoothly through the curve.
Regarding the automatically controlled transmission, in addition to the continuously variable transmission (CVT), there is so a called automatic transmission which has plural and non continuous gear stages, consisting of the gear mechanisms and frictional engagement units. The gear stages are non continuous gear ratios, the gear stages are set by engaging one frictional engagement unit and disengaging another frictional engagement unit. When the gear stage of the automatic transmission changed, the frictional engagement units will engage or disengage, which causes shift shock during a shift change.
A vehicle, that has an automatic transmission, with non continuous gear stages, to go through a curve smoothly, should be controlled by decreasing its speed before the curve. It is also desirable to avoid changing the speed ratio during the curve. Although for a vehicle that has an automatic transmission, if the gear stage is changed from a higher stage to a lower stage to decrease the vehicle speed, it is possible that more than one shift changing will continuously occur, and consequently the shift shock of the gear shift changing will occur as well. That's why if the above mentioned invention is applied the same to a vehicle that has automatic transmission, it is impossible to prevent the occurrence of the shock of the speed changing.
SUMMARY OF THE INVENTION
One object of the present invention is to provide an automatic transmission control system that is able to decrease the number of gear stage shifts as much as possible, when the vehicle, goes through a curve. A control system built according to the present invention is described in the following. The traveling distance to zero the vehicle is determined if the vehicle decreases its speed from the present speed by the predetermined decreasing speed. The number of corners, which are regarded as the places where it is necessary to decrease speed, are detected in the determined traveling distance. The vehicle target speed Vt is calculated for each corner. Vt is set for maintaining proper behavior of the vehicle, stability of operation, and good drivability if the vehicle rounds the corner. The required vehicle speed Vi at the present position of the vehicle calculated to decrease present vehicle speed V to the vehicle target speed Vt for the specific corner. Vi is calculated on the basis of the distance between the present position of the vehicle and each corner. The target deceleration from the present speed V to the required vehicle speed Vi of the specific corner is lager than the threshold value, the specific corner is regarded as the target corner It, and it is counted as the target corner It. The target corner needs the automatic transmission
2
to shift down.
In the invention, if there is more than one corner where vehicle is not able to decreases its speed to the vehicle target speed Vt at a rate less than the target deceleration; and the distance from the present position to the immediate corner is less than the threshold value; and the present vehicle speed V is more than the vehicle target speed Vt; and the vehicle is on the straight road; it is regarded that there is little possibility to accelerate before entering the target corner, the deceleration of the vehicle or the shift down makes little influence against the behavior of the vehicle, stability of the vehicle, and the drivability, then more than one gear stage will be executed.
According to the invention, when the corner is detected on the road ahead of the present position by the navigation system, the gear stage is shifted down only if the deceleration from the present vehicle speed to the required vehicle speed Vi is more than the threshold value. The shifting down of the gear stage is aimed towards getting engine brake effect easily. So it is possible that when the criteria are satisfied, the automatic transmission is controlled in order to get engine brake effect.
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Iwatsuki Kunihiro
Ohta Takashi
Cuchlinski Jr. William A.
Hernandez Olga
Kenyon & Kenyon
Toyota Jidosha & Kabushiki Kaisha
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