US Patent 7487634 Exhaust gas control apparatus

An exhaust gas control apparatus that includes a pressure difference sensor that detects the difference in pressure between the upstream side and the downstream side of a particulate filter (DPNR catalyst), which captures particulate matter that is present in exhaust gas. In the exhaust gas control apparatus, the pipes that introduce the pressure to the pressure difference sensor include an upstream pipe that introduces the pressure on the upstream side of the particulate filter to the pressure difference sensor. The upstream pipe includes an expanded pipe portion, which has an inner diameter greater than that of the portion of the upstream pipe near the pressure difference sensor, near the particulate filter. With this configuration, the deposition of particulate matter, soot, soluble organic fractions, and the like in the upstream pipe is suppressed, which minimizes clogging of the upstream pipe.