Patent ID: 7617700

Claim:
A heat exchanger comprising: an inlet header with associated inlet port for receiving fluid having a variable temperature; an outlet header having an internal wall and an outlet port for discharging fluid at a controlled temperature; a plurality of heat exchange tubes having upstream ends fluidly connected to the inlet header and downstream ends fluidly connected to the outlet header, whereby fluid can flow from the inlet port, into the inlet header, through each tube where heat is transferred, thereby cooling the fluid, before flowing into the outlet header, and out of the outlet port; a thermally actuated valve assembly in the outlet header, spanning the downstream ends of a plurality the tubes adjacent the outlet port, and having a valve body selectively movable between (i) one position permitting flow of fluid from some of the tubes adjacent the outlet port through the outlet header to the outlet port while blocking flow of fluid from all other tubes through the outlet header to the outlet port and (ii) another position permitting flow of fluid from all of the tubes through the outlet header to the outlet port, wherein the valve assembly is rigidly attached to the discharge port and extends into without attachment to the internal wall of the outlet header wherein the valve assembly further comprises an upper section having an upper, perforated sidewall spanning the downstream ends of said plurality of tubes adjacent the outlet port, a lower section having a lower, perforated sidewall spanning the downstream ends of at least one of said other tubes, an imperforate circumferential exterior wall intermediate the upper and lower sidewalls, confronting the interior wall of the outlet header, an internal annular shoulder defining a valve seat within the exterior wall, a thermally responsive wax actuator situated longitudinally within the valve assembly and exposed to fluid discharged from said adjacent tubes into the outlet header through the perforated wall of the upper section of the valve assembly, said actuator having a housing including an annular external shoulder confronting the valve seat, whereby (i) at a first temperature of the fluid entering the header from said plurality of adjacent tubes in the header the external shoulder on the housing fluidly seals against the valve seat such that fluid from the tubes adjacent the outlet port flows through the upper section to the outlet port while flow of fluid from tubes below the valve seat is substantially blocked by the seated valve and the confrontation of said wall with the conduit and (ii) at a higher temperature the wax expands, thereby lifting the housing shoulder off the valve seat to permit fluid flow from tubes below the valve seat to the upper section of the valve assembly and through the outlet header to the outlet port.