The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 27, 2001
Filed:
Aug. 17, 1999
Tae-Kyun Kim, Seoul, KR;
Hyundai Motor Company, Seoul, KR;
Abstract
A hydraulic control system for 4-speed automatic transmissions in which line pressure, drive pressure, reverse pressure and low pressure are selectively supplied from a manual valve to an underdrive clutch, an overdrive clutch, a low-reverse brake, a reverse clutch, and a second brake to realize four forward speeds and a reverse speed. The hydraulic control system includes an underdrive pressure control valve provided between a drive pressure line and the underdrive clutch, and controlled by a first solenoid valve; an overdrive pressure control valve provided between the drive pressure line and the overdrive clutch, and controlled by a second solenoid valve; a second/low-reverse pressure control valve connected to a line pressure line and controlled by a third solenoid valve; a solenoid switch valve controlled by low pressure, line pressure or drive pressure supplied respectively from a low pressure line, the line pressure line and the drive pressure line, and which supplies hydraulic pressure to the low-reverse brake and the second brake; and a fail-safe valve provided between the solenoid switch valve and the second/low-reverse pressure control valve, and is controlled by operational pressure of the underdrive clutch and overdrive clutch, line pressure, and drive or reverse pressure, the fail-safe valve preventing hydraulic pressure supplied from the second/low-reverse pressure control valve from being simultaneously supplied to the second brake and the low reverse brake. The reverse clutch is directly communicated with the manual valve via a reverse pressure line.