Hydraulic control device for automatic transmission

Details Hydraulic control device for automatic transmission Hydraulic control device for automatic transmission

2005-03-01

2005-03-01

Lorence, Richard M. (Department: 3681)

Planetary gear transmission systems or components

Fluid drive or control of planetary gearing

Fluid controlled mechanical clutch or brake

C475S128000, C475S116000, C475S119000, C477S908000, C477S158000

Reexamination Certificate

active

06860830

ABSTRACT:
There is provided a hydraulic control device for an automatic transmission, which is comprised of an engagement state determining section and a protection control section. If the engagement state determining section determines that each clutch, which is supplied with a line pressure via a regulating valve having a spool and has an oil pressure switch disposed in an oil channel, is held in an engaged state when gears are not changed, the protection control section sets a command pressure for the regulating valve to a protective oil pressure lower than the line pressure. This brings the regulating valve into a pressure-regulating state to cause lands of the spool to form apertures that reduce hydraulic vibration applied to the line pressure. This inhibits an oil pressure beyond an acceptable value from being applied to the oil pressure switch, and therefore improves the durability of the oil pressure switch.

REFERENCES:
patent: 5938563 (1999-08-01), Nishio et al.
patent: 6332855 (2001-12-01), Murasugi
patent: 6350214 (2002-02-01), Murasugi
patent: 6478707 (2002-11-01), Jang
patent: 6537170 (2003-03-01), Murasugi et al.
patent: 6540635 (2003-04-01), Sano
patent: 6565474 (2003-05-01), Futamura et al.

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