Planetary gear transmission systems or components – Fluid drive or control of planetary gearing – Fluid controlled mechanical clutch or brake
Reexamination Certificate
2001-02-08
2002-08-06
Wright, Dirk (Department: 3681)
Planetary gear transmission systems or components
Fluid drive or control of planetary gearing
Fluid controlled mechanical clutch or brake
C475S128000
Reexamination Certificate
active
06428440
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus for and a method of controlling an automatic transmission, especially an automatic transmission constituted to carry out a gear change by replacing friction engagement elements.
RELATED ART OF THE INVENTION
There has been known a conventional automatic transmission constituted to control the engagement and release of friction engagement elements by the oil pressure and to carry out a gear change by making friction engagement element replacement in which an engaging control and a releasing control of two different friction engagement elements are conducted at the same time (refer to Japanese Unexamined Patent Publication 9-133205).
When a gear change is carried out by replacing friction engagement elements, as described above, if a releasing control is made too earlier than an engaging control, it generates a racing of engine rotation. On the contrary, if the releasing control is made more slowly than the engaging control, it generates a drive torque drag. Therefore, the friction engagement elements must be replaced while restricting the racing of engine rotation or the generation of drive torque drag.
Accordingly, there has been conducted a control wherein an input shaft torque of a speed change mechanism is estimated, and the sharing burden of the torque transmission is gradually transferred from a release side friction engagement element to an engage side friction engagement element, while the torque capacity capable of transmitting the input shaft torque being shared by the release side friction engagement element and the engage side friction engagement element.
However, due to variations in friction engagement elements and aging thereof, as well as, an estimation error of the input shaft torque, an optimal control of a transmission torque capacity cannot be performed. As a result, there have been cases in that the racing of engine rotation and a torque drag may become large.
SUMMARY OF THE INVENTION
The present invention has been achieved in view of the forgoing problems, and has an object of providing an apparatus for and a method of controlling an automatic transmission capable of restricting a racing of engine rotation and a drive torque drag, regardless of variations in friction engagement elements, aging thereof or an estimation error of input shaft torque.
In order to achieve the above object, the present invention is constituted so that at least one of a transmission torque capacity of an engage side friction engagement element and a transmission torque capacity of a release side friction engagement element at a torque phase is corrected based upon the torque phase state.
According to this constitution, a racing of engine rotation or a drive torque drag is detected based upon the torque phase state and at least one of the transmission torque capacity at the engage side and the transmission torque capacity at the release side is corrected so that the racing of engine rotation or the drive torque drag is restricted.
Here, the constitution may be such that the torque phase time may be detected as the torque phase state.
The torque phase time is the time elapsed from a start of replacing friction engagement torque until completion thereof. As the torque phase time is longer, the racing of engine rotation or the drive torque drag is judged to be greater.
Further, the constitution may be such that, as the torque phase state, a change quantity of input shaft rotation speed of the transmission at the torque phase is detected and also a peak value or an integration value of the change quantity is detected.
According to this constitution, as the change quantity of input shaft rotation speed becomes greater, the racing of engine rotation or the drive torque drag is judged to be greater.
The change quantity of input shaft rotation speed may be calculated as a deviation between a reference input shaft rotation speed calculated based upon a gear ratio prior to gear change and an output shaft rotation speed of transmission, and the aforesaid input shaft rotation speed.
According to this constitution, the input shaft rotation speed corresponding to the gear ratio prior to gear change is obtained as the reference input shaft rotation speed, based upon the gear ratio prior to gear change and the output shaft rotation speed of a speed change mechanism. A deviation of an actual input shaft rotation speed to the reference input shaft rotation speed is calculated as a change quantity of the input shaft rotation speed at the torque phase.
Further, more specifically, the constitution may be such that the transmission capacity of friction engagement element is determined based upon an input shaft torque of the speed change mechanism, a critical torque ratio and a tolerance range that is changed corresponding to a time elapse. A change characteristic of the tolerance range may be changed corresponding to the torque phase state.
According to this constitution, a minimum transmission torque capacity (a critical transmission torque capacity) at that time is obtained based on the input shaft torque and the critical torque ratio and a tolerance range component to the critical transmission torque capacity is set by the tolerance range. By changing the tolerance range with time, the engage side transmission torque capacity is gradually increased from a value smaller than the critical transmission torque capacity while the release side transmission torque capacity is gradually reduced from a value greater than the critical transmission torque capacity, so as to change the torque from the release side to the engage side.
By off-setting the tolerance range corresponding to the torque phase state, the transmission torque capacity of the friction engagement element may be changed and further, a correction of transmission torque capacity with the change of tolerance range may be limited to the engage side friction engagement element.
The other objects and features of the present invention will become understood from the following description with reference to the accompanying drawings.
REFERENCES:
patent: 5123302 (1992-06-01), Brown et al.
patent: 5865708 (1999-02-01), Nishio et al.
patent: 6128565 (2000-10-01), Tsutsui et al.
patent: 6267708 (2001-07-01), Sato et al.
patent: 09133205 (1997-05-01), None
Tanaka Yoshikazu
Yuasa Hiroyuki
Sughrue & Mion, PLLC
Unisia Jecs Corporation
Wright Dirk
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