Patent ID: 6962295
Filing Date: 2005-11-08
Classification: F16H,G05D,Y10T

Abstract:
1. A system for controlling the temperature of an oil used in an automatic hydraulic transmission system comprising: an oil/air heat exchanger; a by-pass thermostat assembly connected to the automatic hydraulic transmission system and to the heat exchanger, the by-pass thermostat assembly having a block having an inner housing for receiving a thermostatic valve therein, the block having an oil inlet passage for receiving oil from the transmission, an oil outlet passage for supplying oil to the heat exchanger, an oil inlet passage for oil returning from the heat exchanger and an oil outlet passage leading the oil back to the transmission, the passages being in fluidic communication through the inner housing, the thermostatic valve having a working element or temperature sensor engaged with and partially enveloped in a tubular casing, the thermostatic valve having a guide pin which extends into a hole in an end plug, which closes an end of the inner housing, for centralizing the working element or temperature sensor in the inner housing, the tubular casing forming a piston slidable within the inner housing in response to a temperature of the oil acting on the working element or temperature sensor, the piston having an open end in proximity to the oil outlet passage leading back to the transmission, the piston being biased by a spring disposed between a bottom of the housing and the piston into a position where the piston blocks the oil outlet passage to the heat exchanger, the piston having four holes located in four opposing points of its circumference in a two by two arrangement, the holes being in fluid communication with the piston open end for bypassing oil therethrough, the piston movable between a first position where oil flows from the oil inlet passage from the transmission to the oil outlet passage to the heat exchanger, and a second position where the piston blocks the oil outlet passage to the heat exchanger and oil flows through the boles and open end back to the transmission system.