Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Transmission control
Reexamination Certificate
2000-10-23
2002-04-16
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Transmission control
C701S058000, C701S060000, C477S163000, C477S154000
Reexamination Certificate
active
06374170
ABSTRACT:
TECHNICAL FIELD
This invention relates to an automatic transmission shift control utilizing adaptive correction of calibrated shift parameters, and more particularly to a method of applying adaptive corrections for a given shift to the shift parameters of one or more related shifts.
BACKGROUND OF THE INVENTION
In general, a motor vehicle automatic transmission includes a number of gear elements and selectively engageable friction elements (referred to herein as clutches) that are controlled to selectively establish reverse or forward speed ratios between the transmission input and output shafts. Shifting from a currently established speed ratio to new speed ratio involves, in most cases, disengaging a clutch (off-going clutch) associated with the current speed ratio and engaging a clutch (on-coming clutch) associated with the new speed ratio.
Although transmission shift control algorithms utilize a variety of control strategies, most of them rely on a number of calibrated parameters for initiating clutch engagement and disengagement in the course of a shift. These parameters may pertain directly to physical characteristics of the transmission (fill volume of a clutch, for example), or to clutch pressure levels (on-coming or off-going) at specified points of the shift sequence. Although a shift can be calibrated in this manner to produce excellent shift quality under varying speed and load conditions in a new transmission, it is impractical to individually calibrate the control parameters for every transmission in a mass production environment. Moreover, it is known that the characteristics of any transmission vary somewhat with age and wear, producing a gradual degradation in shift quality if the parameters are not correspondingly adjusted. For these reasons, adaptive control strategies have been developed for automatically adjusting the calibrated parameters during operation of the transmission to achieve and maintain consistent high quality shifting in any given transmission. In general, this involves monitoring various transmission parameters during a shift to detect specified shift quality aberrations (such as engine flaring or clutch tie-up), and correcting one or more of the calibrated parameters upon completion of the shift so that the shift quality will be improved in the next shift of the same type. Thus, each shift type (1-2 upshift, for example) has its own set of calibrated parameters, and such parameters are subject to adaptive correction each time that shift occurs. Exemplary controls of this type are described in the U.S. Pat. Nos. 4,653,350 to Downs et al., and 5,072,390 to Lentz et al., both of which are assigned to the assignee of the present invention.
Adaptive correction strategies can become somewhat more complicated when the transmission controls are configured to provide different shift modes (Normal/Performance, or Normal/Towing, for example) since certain types of shifts may not occur until the transmission has been in service for a long time. This situation is addressed in the U.S. Pat. No. 5,151,858 to Milunas et al., also assigned to the assignee of the present invention, in the context of a control configured to selectively provide either Normal and Performance shift modes. Mode-specific adaptive correction tables are provided for each type of shift, with the Normal mode table being adjusted based only on Normal mode shifting, and the Performance mode table being adjusted based only on Performance mode shifting. In this scheme, Normal mode shifts utilize the Normal mode correction table, while Performance mode shifts utilize both the Normal mode correction table and the Performance mode correction table. This not only allows the Performance mode shift parameters to be adaptively adjusted based on a Normal mode shift of the same type, but also preserves a difference between Normal and Performance mode shifting.
The control described in the preceding paragraph may be regarded as a cross-adaptive control because adaptive corrections learned in the course of one type of shift (X-Y Normal mode shift) are utilized to adaptively correct corresponding parameters for different, but related, type of shift (X-Y Performance mode shift). However, the cross-adaptive learning described by Milunas et al. is relatively limited, and fails to recognize that the adaptive parameters for different types of shifts converge on respective optimum values at different rates, and that cross-adaptive controls that are appropriate when the transmission is relatively new may not be appropriate after the vehicle has been in service for some time. Accordingly, what is needed is a cross-adaptive control that maximizes the sharing of adaptive correction among related types of shifts, without negatively impacting shift quality as the adaptively corrected parameters converge on respective optimum values.
SUMMARY OF THE INVENTION
The present invention is directed to an improved cross-adaptive control method for automatic shift transmissions in which an initial methodology for sharing adaptive corrections is automatically modified as the adapted parameters for various related types of shifts converge on respective optimum values. Individual shift types in a grouping or sub-grouping of related shifts are initially categorized to indicate the degree of cross-adaptive correction sharing. When shift parameter convergence for a given shift occurs, that shift is re-categorized, thereby modifying the initial cross-adaptive methodology to restrict further cross-adaptive correction. Additionally, an adaptive parameter for a given shift type may be re-categorized to permit further cross-adaptive correction if the shift has not been performed for a prolonged period and the corresponding parameter of a related shift has been adjusted by at least a predetermined amount since the last cross-adaptive correction occurred. In this way, the cross-adaptive methodology automatically evolves to suit individual transmission operating characteristics and conditions, and effectively prevents a situation where adaptive corrections developed for one shift degrade the shift quality of a related shift.
In a preferred mechanization, a non-volatile data array is used to efficiently store shift grouping, categorization and convergence data for each shift type subject to cross-adaptive control. This reduces the complexity of the cross-adaptive control software and facilitates factory calibration and subsequent dealer resetting if required.
REFERENCES:
patent: 4070927 (1978-01-01), Polak
patent: 4653350 (1987-03-01), Downs et al.
patent: 5072390 (1991-12-01), Lentz et al.
patent: 5089963 (1992-02-01), Takahashi
patent: 5099428 (1992-03-01), Takahashi
patent: 5151858 (1992-09-01), Milunas et al.
patent: 5601506 (1997-02-01), Long et al.
patent: 5758303 (1998-05-01), Sugiyama et al.
patent: 5812957 (1998-09-01), Lizuka
Hubbard Gregory A
Kresse John P
Runde Jeffrey Kurt
Cuchlinski Jr. William A.
General Motors Corporation
Hodges Leslie C.
Marc-Coleman Marthe Y.
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