Interrelated power delivery controls – including engine control – Transmission control – Engine controlled by transmission
Patent
1997-02-13
1999-07-13
Wright, Dirk
Interrelated power delivery controls, including engine control
Transmission control
Engine controlled by transmission
477158, 477174, 477906, 477125, 701 59, F16H 6100
Patent
active
059218851
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a control system for an automatic transmission of a vehicle, and more particularly to a control system including pressure modulating valve to modulate hydraulic pressure acting on frictional engagement means such as a clutch and a brake.
BACKGROUND ART
As is well-known in the art, when shifting of an automatic transmission for a vehicle is executed, in order to prevent a delay in the shift and a shift shock, it is necessary to control hydraulic pressure supplied to the frictional engagement means such as a clutch and a brake. Therefore, control systems have been developed which are so constructed that the engaging pressure acting on one of the two frictional engagement means required to switch between engaged and released states is directly controlled by means of a pressure modulating valve.
For instance, in an automatic transmission equipped with a gear train wherein one brake is engaged in the forward second gear stage and the brake is released with another brake engaged in up-shifting to the forward third gear stage, gear shifting between these gear stages becomes so-called clutch-to-clutch shift. It is sometimes necessitated to control the hydraulic pressure for one of the two brake (for example a brake to set the forward second speed gear stage for instance) by means of a pressure control valve adjustable in pressure modulating level.
Although a signal pressure for setting the pressure modulating level of the pressure control valve could be applied by a linear solenoid valve specially devised for the control valve, inconvenience of large-sized control system will be caused due to increased number of solenoid valves in such a structure.
In order to overcome the above-mentioned inconvenience, application of a conventional linear solenoid valve as a measure for changing the pressure modulating level of the above-mentioned control valve can be considered. In this case, since the linear solenoid valve is to be operated for setting a pressure modulating level of the above-mentioned control valve when required while being operated for its primary purpose on the other hand, the linear solenoid valve is necessarily so constructed as to switch its output pressure (signal pressure) between primary control object and the control valve, making it general to use a switching valve; wherein, in addition, the conventional linear solenoid valve can be used both for its primary purposes and as the switching valve.
In addition, it can be considered to take measures against pressure modulation failure; for example, to apply the line pressure provided through a shifting valve directly to the brake in a case of a failure where adjustment of braking pressure for the second gear stage by means of the control valve is impossible, thereby making the setting of the second gear stage sure.
When the control system is composed as mentioned above, smooth clutch-to-clutch shifting can be accomplished without requiring increased number of the valves in particular. However, in a case where the signal pressure is not supplied to the control valve due to a failure occurred in the aforementioned switching valve, the line pressure is directly applied to the brake in setting the second gear stage; thereby regulation of hydraulic pressure applied to the brake for the second speed gear stage cannot be performed, resulting in possibility of increased shift shock.
In addition, in case of the gear shifting from the third gear stage to the second gear stage which is so-called clutch-to-clutch shift for example, if the line pressure is applied to the brake for the second gear stage during this gear shifting, there occurs a so-called tie-up condition, wherein two brakes have unexpectedly torque capacity; causing an excessive braking torque in addition to aggravated shift shock and thereby possibilities of deterioration in durability of the friction material of the brake means due to its wear.
The primary object of the present invention is to provide a control system for automatic transmissions capable o
REFERENCES:
patent: 4393732 (1983-07-01), Suzuki et al.
patent: 4718311 (1988-01-01), Hayakawa et al.
patent: 4785689 (1988-11-01), Iwatsuki et al.
patent: 4827806 (1989-05-01), Long et al.
patent: 4982624 (1991-01-01), Takada et al.
patent: 5083481 (1992-01-01), Smith et al.
patent: 5103692 (1992-04-01), Shimanaka et al.
patent: 5109734 (1992-05-01), Fujiwara
patent: 5133231 (1992-07-01), Goto et al.
patent: 5291804 (1994-03-01), Kashihara et al.
patent: 5293789 (1994-03-01), Goto et al.
patent: 5363724 (1994-11-01), Asahara et al.
patent: 5403248 (1995-04-01), Ando et al.
patent: 5433124 (1995-07-01), Person
patent: 5472389 (1995-12-01), Ando et al.
patent: 5496228 (1996-03-01), Takata et al.
patent: 5501645 (1996-03-01), Taniguchi et al.
patent: 5505673 (1996-04-01), Tsukamoto et al.
patent: 5527233 (1996-06-01), Tabata et al.
patent: 5613921 (1997-03-01), Sugiyama et al.
patent: 5665027 (1997-09-01), Oba et al.
patent: 5669849 (1997-09-01), Tabata et al.
patent: 5682792 (1997-11-01), Liesener et al.
Hojo Yasuo
Hukatsu Akira
Miyata Hideki
Tabata Atsushi
Aisin AW Kabushiki Kaisha
Kwon Peter T.
Toyota Jidosha & Kabushiki Kaisha
Wright Dirk
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