| 摘要 |
An EGR system has two vacuum modulation valves, one responsive to venturi vacuum and "EGR" pressure (which prevails just upstream of the EGR flow control valve) and the other responsive to venturi vacuum and induction vacuum. The first valve predominately dilutes the vacuum operating the EGR flow control valve during heavy load operation while the second valve predominately dilutes said vacuum during light load and/or high speed operation. With this combination, excessive EGR is avoided during said light load and high speed operations, respectively.
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