Exhaust heat recovery device

Abstract

An exhaust heat recovery device provided in an exhaust system of an engine etc., having a heat exchanger for performing heat exchange between exhaust gas and a medium, a bypass route through which the exhaust gas bypasses the heat exchanger, and a valve body for opening and closing the bypass route, wherein wiring and piping are reduced to make the device advantageous in cost. The exhaust heat recovery device has a valve body that, when the flow rate of the exhaust gas is equal to or higher than a predetermined value, opens the bypass route from a closed state against urging force of an urging body. The exhaust heat recovery device also has a temperature-activated actuator that opens the valve body when the temperature of the medium is equal to or higher than a predetermined value. The construction causes the valve body to be opened when at least either of the flow rate of the exhaust gas and the temperature of the medium is equal to or higher than the predetermined value.

1 . An exhaust heat recovery device provided in an exhaust system of an internal combustion engine or the like and comprising a heat exchanger for performing heat exchange between exhaust gas and a medium, a bypass route through which the exhaust gas bypasses the heat exchanger, and a valve body for opening and closing the bypass route,
 wherein said exhaust heat recovery device further comprises a valve body that operates to open said bypass route from a closed state against urging force of an urging member when a flow rate of the exhaust gas is equal to or higher than a predetermined value, and a temperature-activated actuator that causes said valve body to open when the temperature of said medium is equal to or higher than a predetermined value, whereby said valve body operates to open when at least one of the flow rate of the exhaust gas and the temperature of the medium is equal to or higher than the corresponding predetermined value.   
   
   
       2 . The exhaust heat recovery device according to  claim 1 , further comprising a crank mechanism that causes said valve body to open by an expanding movement of said temperature-activated actuator which expands and contracts according to the temperature of said medium, and a floating mechanism that couples the contracting movement of said temperature-activated actuator and the closing movement of said valve body in an floating state. 
   
   
       3 . The exhaust heat recovery device according to  claim 1 , wherein said temperature-activated actuator is a thermoelement which expands and contracts by an incorporated wax. 
   
   
       4 . The exhaust heat recovery device according to  claim 2 , wherein said temperature-activated actuator is a thermoelement which expands and contracts by an incorporated wax.