HYDRAULIC CONTROL SYSTEM FOR AN AUTOMATIC TRANSMISSION HAVING DEFAULT GEARS APPLIED THROUGH A CLUTCH HYDRAULIC EXHAUST CIRCUIT

摘要

A hydraulic control system for a transmission is provided. The hydraulic control system provides one or more default gears during a default condition when the transmission loses electronic control. The hydraulic control system includes a default enable valve, a default select valve, and a plurality of clutch regulation valves. The default enable valve and the default select valve feed hydraulic fluid through exhaust circuits to a set number of the clutch regulation valves during a default condition in order to provide a default gear ratio

主权项

1. A hydraulic control system for a transmission of a motor vehicle, the hydraulic control system comprising:
a pressure regulation subsystem in fluid communication with a pump for providing pressurized hydraulic fluid; a default control subsystem in fluid communication with the pressure regulation subsystem; a clutch selectively engaged upon receipt of a fluid signal; and a clutch regulation valve assembly having an exhaust port in fluid communication with the default control subsystem, an input port in communication with the pressure regulation subsystem, and a clutch feed port in fluid communication with the clutch, wherein the clutch regulation valve assembly selectively allows fluid communication between the input port and the clutch feed port and the exhaust port and the clutch feed port; and wherein the clutch is selectively engaged in a normal mode of operation by a fluid signal from the input port and the clutch is selectively engaged in default mode of operation by a fluid signal from the exhaust port.