Exhaust heat recovery system

Abstract

An exhaust heat recovery system 25 provided with a plurality of heat pipes 60, 61 provided with heat recovery parts 60 a, 61 a and heat exchange parts 60 b, 61 b . The heat pipes recover heat from exhaust gas exhausted from an internal combustion engine at the heat recovery parts and transfer this recovered heat to an object to be heated at the heat exchange parts. The heat recovery part 60 a of the first heat pipe 60 recovers heat from the exhaust gas at an exhaust purification catalyst 20 ′ provided in an engine exhaust passage or its upstream side. The heat recovery part 61 b of the second heat pipe 61 recovers heat from the exhaust gas at the downstream side of the exhaust purification catalyst. Due to this, there is provided an exhaust heat recovery system which can recover at least a fixed amount of exhaust heat at all times while maintaining a warm-up performance of the exhaust purification catalyst.

1 . An exhaust heat recovery system provided with a plurality of heat transport devices each provided with a heat recovery part and a heat exchange part, each heat transport device recovering heat at the heat recovery part from exhaust gas exhausted from an internal combustion engine and transferring this recovered heat to an object to be heated at the heat exchange part, wherein
 the heat recovery part of a first heat transport device recovers heat from an exhaust purification catalyst provided in an engine exhaust passage or an upstream side of the same, while the heat recovery part of a second heat transport device recovers heat from the exhaust gas at a downstream side of said exhaust purification catalyst.   
   
   
       2 . An exhaust heat recovery system as set forth in  claim 1 , wherein the heat transport capacities of said plurality of heat transport devices differ for each heat transport device. 
   
   
       3 . An exhaust heat recovery system as set forth in  claim 2 , wherein said first heat transport device has a heat capacity smaller than a heat capacity of the second heat transport device. 
   
   
       4 . An exhaust heat recovery system as set forth in  claim 3 , wherein said heat transport devices are heat pipes, and the amount of the heat medium in the heat pipe differs between the first heat transport device and second heat transport device. 
   
   
       5 . An exhaust heat recovery system as set forth in  claim 1 , wherein said heat exchange parts heat the fluid to be heated. 
   
   
       6 . An exhaust heat recovery system as set forth in  claim 5 , wherein the flow rate of the fluid to be heated flowing in the heat exchange parts is controlled in accordance with the temperature of the exhaust gas exhausted from said internal combustion engine. 
   
   
       7 . An exhaust heat recovery system as set forth in  claim 5 , wherein said heat transport devices are heat pipes and, when the temperature of said second heat transport device is lower than a reference temperature, the flow rate of the fluid to be heated flowing through the heat exchange part of said second heat transport device is made zero. 
   
   
       8 . An exhaust heat recovery system as set forth in  claim 5 , wherein the system is further provided with a route for the fluid to be heated passing through the heat exchange part of said first heat transport device and the heat exchange part of said second heat transport device and a flow regulator valve provided in a channel between the heat exchange part of said first heat transport device and the heat exchange part of said second heat transport device, and said flow regulator valve regulates the flow rate of the fluid to be heated passing through the heat exchange part of said second heat transport device in the fluid to be heated passing through the heat exchange part of said first heat transport device.