Patent ID: 6012550
Filing Date: 2000-01-11
Classification: F16H,G05D

Abstract:
In an automatic transmission which has an automatic transmission fluid (ATF) cooler and an oil tank, a bypass device for automatic transmission fluid comprising:a valve housing comprising,a first port adapted for receiving ATF (automatic transmission fluid) for said automatic transmission,a second port adapted for discharging the ATF from the valve housing into said ATF cooler,a third port adapted for receiving the ATF from the ATF cooler, anda fourth port adapted for discharging the ATF from the valve housing into said oil tank of the transmission;a valve spool movably received in said valve housing, the valve spool comprising an internal passage and a bypass passage, the valve spool adapted for selectively allowing the first and second ports to communicate together and simultaneously allowing the third and fourth ports to communicate together via the internal passage or allowing the first and fourth ports to communicate together via the bypass passage;a thermal expansion bar provided at one end of said valve spool and adapted for axially moving the valve spool in either direction in accordance with the ATF temperature; anda spring provided in the valve housing at a position opposite to said thermal expansion bar and adapted for biasing the valve spool.