Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
2002-07-29
2004-05-11
Beaulieu, Yonel (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S051000, C701S055000, C701S056000
Reexamination Certificate
active
06735509
ABSTRACT:
This application is based on Japanese Patent Application Nos. 2001-232349 filed on Jul. 31, 2001, the contents of which are incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to an apparatus for controlling a drive system for an automotive vehicle, which drive system includes a drive power source and an automatic transmission. More particularly, the invention is concerned with improvements of an apparatus arranged to feedback-control an engaging force of a frictional coupling device which is released to effect a shift-down action of the automatic transmission, concurrently with an engaging action of another frictional coupling device, during an operation of a manually operable vehicle accelerating member to drive the vehicle.
2. Discussion of Related Art
In an automotive vehicle, there is widely used an automotive transmission having a plurality of forward drive positions which have respective different speed ratios and which are selectively established by respective combinations of engaging and releasing actions of a plurality of frictional coupling devices. An automatic transmission of this type is automatically shifted up and down on the basis of suitably selected parameters such as an operating amount of an accelerator pedal and a running speed of the vehicle, and according to a predetermined relationship between a running condition of the vehicle defined by the selected parameters and the operating position to which the automatic transmission should be shifted. The predetermined relationship may be represented by a stored shift-boundary data map, as indicated in the graph of
FIG. 6
by way of example. It will be understood from shift-down boundary lines indicated by broken lines in
FIG. 6
that the automatic transmission is shifted down to increase the sped ratio when the vehicle running speed V is lowered or when an opening angle &thgr;
TH
of a throttle valve (corresponding to the operating amount of the accelerator pedal) is increased. The speed ratio is a ratio of an input speed to an output speed of the automatic transmission. Some of the forward drive positions are established by concurrent engaging and releasing actions of respective two frictional coupling devices, namely, an engaging action of a first frictional coupling device and a releasing action of a second frictional coupling device, which take place concurrently with each other. When the automatic transmission is shifted by such concurrent engaging and releasing actions of the two frictional coupling devices, there may arise abnormal shifting behaviors of the frictional coupling devices, which cause a racing of a drive power source such as an engine, and a so-called “tie-up” behavior which causes a delayed shifting action of the automatic transmission to the selected forward drive position. The racing of the drive power source takes place when the first frictional coupling device to be released is prematurely brought to a substantially released state while the second frictional coupling device to be engaged is still in a substantially fully released state. On the other hand, the tie-up behavior takes place when the second frictional coupling device is prematurely brought to a substantially engaged state while the first frictional coupling device is still in a substantially fully engaged state. Therefore, the concurrent engaging and releasing actions of the two frictional coupling devices must be intricately controlled. JP-A-8-145157 discloses an example of controlling concurrent engaging and releasing actions of the two frictional coupling devices to effect a shift-up action of the automatic transmission to reduce the speed ratio, such that the engaging force of the second frictional coupling device to be engaged is controlled in a feedback fashion, and such that the engaging force at which the feedback control is initiated is updated by a learning compensation technique.
In a control apparatus disclosed in the above-identified publication, however, the first frictional coupling device to be released is not controlled is instantaneously released without controlling its engaging force in the process of the releasing action. This control apparatus suffers from a racing of the drive power source, which takes place when the releasing action of the first frictional coupling device and the engaging action of the second coupling device are effected to effect a shift-down action of the automatic transmission to increase the speed ratio, in response to an abrupt or rapid increase of a vehicle-operator's required vehicle drive force to drive the vehicle. The required vehicle drive force may be represented by the operating amount of the accelerator pedal, and may reflect the operator's desire to accelerate the vehicle. It is also noted that such a shift-down action of the automatic transmission in response to an abrupt increase of the operator's required vehicle drive force is generally required to be completed in a relatively short time, in order to meet the operator's desire to accelerate the vehicle. In this respect, it would be difficult to accurately feedback-control the engaging force of the first frictional coupling device in the process of its releasing action, due to a low control response of the engaging force.
SUMMARY OF THE INVENTION
The present invention was made in the light of the background art discussed above. It is therefore an object of the present invention to provide an apparatus for controlling a vehicle drive system including an automatic transmission, which apparatus prevents or minimizes a racing of a drive power source or any other drawback which may be caused by abnormal shifting behaviors of two frictional coupling devices in the process of respective concurrent engaging and releasing actions thereof to effect a shift-down action of the automatic transmission during an operation of a vehicle accelerating member to drive the vehicle.
The object indicated above may be achieved according to one aspect of this invention, which provides an apparatus for controlling a drive system of an automotive vehicle including a manually operable vehicle accelerating member, a drive power source, and an automatic transmission having a plurality of forward drive positions which have respective different speed ratios and which are selectively established by respective combinations of engaging and releasing actions of a plurality of frictional coupling devices, the apparatus comprising feedback control means operable upon a shift-down action of the automatic transmission which is effected by concurrent releasing and engaging actions of respective first and second frictional coupling devices of the plurality of frictional coupling devices, during an operation of the vehicle accelerating member to drive the automotive vehicle with the drive power source, the feedback control means feedback-controlling an engaging force of the first frictional coupling device, the apparatus being characterized by further comprising: shifting-abnormality detecting means for detecting one of a racing of the drive power source and a tie-up behavior of the first and second frictional coupling devices during the shift-down action of the automatic transmission; and learning compensation means operable upon detection of the above-indicated one of the racing and the tie-up behavior by the shifting-abnormality detecting means, for effecting learning compensation of an initial value of the engaging force of the first frictional coupling device at which a feedback control of the engaging force by the feedback control means is initiated.
The vehicle drive system control apparatus according to the first aspect of this invention describe above is arranged to feedback-control the engaging force of the first frictional coupling device which is released to effect the shift-down action during an operation of the manually operable vehicle accelerating member to drive the vehicle, and is further arranged to change the initial value of the engaging
Ayabe Atsushi
Kimura Hiromichi
Nakamura Mitsuhiro
Ogasawara Hideaki
Sakamoto Naoyuki
Beaulieu Yonel
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Toyota Jidosha & Kabushiki Kaisha
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