| 摘要 |
An i.c. engine EGR system is described having a controller (12,FIG.1) for coordinating exhaust gas recirculation (EGR) flow through and around a plurality EGR coolers differently depending on operating conditions. The EGR coolers may be in series (210,212, figs.2,3A-D) or in parallel (410.412, figs.4, 5A-D). The controller is operable to control the opening and closing of various valves so as to vary the flow between the EGR coolers and associated bypasses. By appropriate control of the EGR flow through a plurality of coolers and at least one bypass it is possible to maintain cooler output above fouling limits and also maintain intake manifold temperature at an appropriate level for combustion. |
