Exhaust gas analyzer

An apparatus with an exhaust gas analyzer wherein a soot measuring system that can measure soot in exhaust gas is connected with an exhaust gas line through which a part or all of the exhaust gas discharged from an internal combustion engine flows, the improvement comprising:

• the soot measuring system including a diluter having a sample introducing port connected with (i) a standard gas line through which standard gas whose hydrocarbon concentration is known and which is supplied from a standard gas source flows and (ii) the exhaust gas line, and which can be switched so as to selectively dilute either one of the exhaust gas and the standard gas with diluent gas which is compressed to be introduced to an internal main path and extrudes it, a dilution ratio adjusting device that can adjust the dilution ratio of the diluter, and a soot detector that detects soot in the exhaust gas or the standard gas diluted by the diluter;
• the diluter being so arranged that a narrow part whose flow path diameter is narrowed and a diffusible part whose flow path diameter is extended are serially arranged on the internal main path through which the diluent gas passes so as to form a negative-pressure area that is negative-pressured because the diluent gas is accelerated, and the diluter sucks the exhaust gas through a communicating path communicating with the negative-pressure area, mixes the exhaust gas with the diluent gas and then extrudes it;
• and
• the dilution ratio adjusting device changes a flow amount of the diluent gas introduced into the diluter within a range where a flow amount of the exhaust gas sucked by the diluter is kept generally constant by a predetermined operation from outside.