| 摘要 |
<P>PROBLEM TO BE SOLVED: To minimally maintain the deposit of soot by removing the soot in all heat transfer pipes of a multi-pipe type EGR gas cooling device by a comparatively simple means, and to maintain a large heat exchange amount and a state of the initial low flow-pass resistance of EGR gas. <P>SOLUTION: The multi-pipe type EGR gas cooling device is characterized in that EGR piping at least at one side of an EGR gas flow-in side, or at an EGR gas flow-out side of the multi-pipe type EGR gas cooling device is divided into two systems, there is arranged an on-off valve for on/off-controlling each system, and the switch valve can form a first state that all EGR gas flow amounts are made to flow to all the heat transfer pipes, a second state that all the amounts of the EGR gas flows are made to flow to an almost half of heat transfer pipe groups, and a third state that all the amounts of the EGR gas flows are made to flow to the heat transfer pipe groups to which all the amounts of the EGR gas flows have not made to flow in the second state. <P>COPYRIGHT: (C)2012,JPO&INPIT |
