Abstract: A heat exchanger tube is constituted by a flat tube body 14 shaped like a plurality of cylindrical tubes arranged mutually proximally in a plane and connected together at mutually proximate portions of the tubes as communicating portions 13. Cylindrical portions 15 corresponding to the cylindrical tubes of the flat tube body 14 have inner peripheries formed with swirling-flow-forming protrusions 16 directed along spiral trajectories coaxial with central axes O of the cylindrical portions 15 so that the respective cylindrical portions 15 may have individual swirling flows of the exhaust gas 10.

Abstract: A heat exchanger tube is constituted by a flat tube body 14 shaped like a plurality of cylindrical tubes arranged mutually proximally in a plane and connected together at mutually proximate portions of the tubes as communicating portions 13. Cylindrical portions 15 corresponding to the cylindrical tubes of the flat tube body 14 have inner peripheries formed with swirling-flow-forming protrusions 16 directed along spiral trajectories coaxial with central axes O of the cylindrical portions 15 so that the respective cylindrical portions 15 may have individual swirling flows of the exhaust gas 10.

Abstract: An exhaust gas recirculation (EGR) cooler includes a plurality of tubes and a shell enclosing the tubes. During use, cooling water is supplied to and discharged from the shell, and exhaust gas is guided from a diesel engine into the tubes to be heat exchanged with the cooling water. An inner periphery of each of the tubes is formed with three streaks of spiral protrusions running without crossing and with phases peripherally shifted to each other. A pitch P ratio of each of the spiral protrusions to an inner diameter of each of the tubes is 2.0-4.0, and a ridge height H ratio of each of the spiral protrusions to the inner diameter of each of the tubes is 0.1-0.2.

Abstract: An EGR cooler including tubes and a shell enclosing the tubes. Cooling water is supplied into and discharged from the shell. Exhaust gas is guided from a diesel engine into the tubes for thermal exchange of the exhaust gas with the cooling water. A bypass flow path for guiding the cooling water is constituted within the shell so as to prevent stagnation of the cooling water in the shell.

Abstract: An EGR cooler is provided which is satisfactorily applicable to a diesel engine with no substantial lowering in performance. With respect to the EGR cooler which is provided with tubes 3 and a shell 1 enclosing the tubes 3, cooling water 9 being supplied to and discharged from the shell 1, exhaust gas 10 being guided from a diesel engine into the tubes 3 to be heat exchanged with the cooling water 9, an inner periphery of each of the tubes 3 is formed with three streaks of spiral protrusions 12, 13 and 14 running without crossing and with phases peripherally shifted to each other, a pitch P ratio (P/D) of each of the spiral protrusions 12, 13 and 14 to an inner diameter D of each of the tubes 3 being 2.0-4.0, a ridge height H ratio (H/D) of each of the spiral protrusions 12, 13 and 14 to the inner diameter D of each of the tubes 3 being 0.1-0.2.

Abstract: Provided is an EGR cooler which can solve the problem of the vibrated tubes without causing thermal deformation due to stagnation of the coolant water, without complexity of piping in the coolant water system and without increase in pressure loss. The EGR cooler comprises tubes 3 and a shell surrounding the tubes 3, the coolant water being supplied and discharged to and from the shell 1 and being passed through the respective tubes 3 so as to make heat exchange of the exhaust gas with the coolant water. In the shell 1, an intermediate support plate 13 with a plurality of through-holes 14 is arranged and mutually adjacent ones of the tubes 3 are grouped for penetratingly fixture to the through-hole 14. A coolant water passage 15 is ensured between the tubes 3 grouped and penetratingly fixed to the same through-hole 14 of the intermediate support plate 13 for free communication between the tubes 3.

Abstract: Coolant water is prevented from stagnating with no restriction to a mounted posture of an EGR cooler to a vehicle. The EGR cooler has tubes 3 and a shell 1 surrounding the tubes 3, coolant water 9 being fed into and discharged from the shell 1, exhaust gas being passed through the tubes 3 for heat exchange of the exhaust gas with the coolant water 9. An annular coolant-water supply chamber 11 is fitted over the shell 1 near an axial end of the shell 1. A coolant-water inlet pipe 4 is connected to a periphery of the supply chamber 11. Communicating holes 12 are formed at a plurality of peripheral positions sequentially along a portion of the shell 1 surrounded by the supply chamber 11 such that the holes have gradually reduced diameters as they are apart from the connection of the shell with the inlet pipe 4, so that the coolant water 9 may be introduced into the shell 1 substantially evenly through the communicating holes 12.

Abstract: An EGR cooler has tubes and a shell for enclosing the tubes. Cooling water is supplied into and discharged from the shell and exhaust gas from a diesel engine is guided into each of the tubes so as to conduct heat exchange of the exhaust gas with the cooling water. An inner periphery of each of the tubes is formed with spiral protrusions each having an inclination angle in a range of 26°–50° to a plane perpendicular to an axis of the tube.

Abstract: An EGR cooler including tubes and a shell enclosing the tubes. Cooling water is supplied into and discharged from the shell. Exhaust gas is guided from a diesel engine into the tubes for thermal exchange of the exhaust gas with the cooling water. A bypass flow path for guiding the cooling water is constituted within the shell so as to prevent stagnation of the cooling water in the shell.

Abstract: A profile of the casing 20 is formed into a circular pipe shape, and the two gas coolers 10a, 10b are integrated into one body so that the longitudinal directions of the respective gas coolers can be substantially parallel with each other. Due to the above structure, it is possible to make the coolant flow smoothly in the casing 20 and stagnation of the coolant seldom occurs. Accordingly, as boiling of the coolant can be suppressed, it is possible to prevent the heat transfer coefficient from being remarkably deteriorated. Further, it is possible to suppress the generation of cracks, in the tubes 11, which are caused by heat stress.

Abstract: An EGR cooler has tubes (3) and a shell (1) for enclosing the tubes (3). Cooling water (9) is supplied into and discharged from the shell (1) and exhaust gas (10) from a diesel engine is guided into each of the tubes (3) so as to conduct heat exchange of the exhaust gas (10) with the cooling water (9). An inner periphery of each of the tubes (3) is formed with spiral protrusions (12, 13) each having an inclination angle (?) in a range of 26°-50° to a plane perpendicular to an axis (x) of the tube (3).

Abstract: An EGR cooler including a flat box shell having an inlet for introducing cooling water and an outlet for discharging the cooling water, plates positioned at axial open ends of the shell to close the axial open ends thereof, hoods positioned at sides of the plates away from the shell to enclose end faces of the plates, tubes extending within the shell and having ends penetrating through the plates, the tubes for passing exhaust gas from one hood to the other for thermal exchange with the cooling water, guide plates curved away from the axial extension of the shell toward longer sides of the end face of the shell and provided in the hood on an inlet side of the exhaust gas, a bar positioned between the guide plates and extending in a direction of shorter sides of the end face of the shell for dividing a stream of the exhaust gas.