Thermal by-pass valve with pressure relief capability

Abstract

A by-pass valve for a heat exchanger circuit that includes a cooler (12) has a chamber (48) and ports for flow of fluid into and out of this chamber. A thermally sensitive actuator (64) is mounted in the chamber and can extend or retract in dependence on its body temperature as influenced by temperature of the fluid. A by-pass valve seat (154) is arranged in a valve housing along with a by-pass valve member (62) movable by the actuator into or out of engagement with the seat. A relief valve is mounted in the chamber and has a relief valve member (210) movable between closed and open positionsin order to close or open pressure relief ports. This relief valve member is biased towards the closed position. Excessive pressure build up in an end section of the chamber causes the relief valve member to move to its open position.

Description

technical field

[0001] The invention relates to a bypass valve for a heat exchanger circuit in which there is a cooler or cooler unit for a heat exchange fluid. Background technique

[0002] For example in the automotive industry, heat exchangers are used to cool or heat certain fluids such as engine oil or transmission fluid or oil. For example, in the case of transmission fluid, a heat exchanger called a cooler is used to cool the transmission fluid. The heat exchanger is usually located remote from the transmission and under normal operating conditions receives hot transmission oil from the transmission through a supply line, cools it and sends it back to the transmission through a return line. However, when the transmission is cool, such as at start-up, the transmission oil or fluid is very viscous, if at all, and does not flow easily through the heat exchanger. In this case, the transmission may starve of oil and cause damage or erratic performance. Cumulative damage...

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