Exhaust gas analyzing device, gas supply method, and exhaust gas sampling device

A method of supplying a gas to an exhaust gas analyzing device including a sampling channel through which an exhaust gas from an internal combustion engine flows, an analyzer that is connected to the sampling channel and analyzes particulate matter in the exhaust gas, a diluter provided upstream of the analyzer in the sampling channel, a recirculation channel that branches from a branch point set downstream of the diluter in the sampling channel, is connected to the diluter, and directs part of the exhaust gas flowing through the sampling channel toward the analyzer from downstream to upstream of the sampling channel, and a pump that is provided in the recirculation channel to move the part of the exhaust gas flowing through the sampling channel from downstream to upstream of the sampling channel by returning the part of the exhaust gas from the branch point to the diluter through the recirculation channel, the method comprising:

• connecting an additional channel through which a calibration gas or a purge gas flows to the recirculation channel or the sampling channel, and
• guiding the calibration gas or the purge gas to the sampling channel by opening an opening and closing mechanism provided in the additional channel, wherein an additional flow rate as a flow rate of the calibration gas or the purge gas introduced from the additional channel into the recirculation channel or the sampling channel is larger than an analysis gas flow rate as a flow rate of a gas introduced into the analyze, and wherein the recirculation channel is provided with a first filter that captures the particulate matter.

An exhaust gas analyzing device comprising:

• a sampling channel through which an exhaust gas from an internal combustion engine flows;
• an analyzer that is connected to the sampling channel and analyzes particulate matter in the exhaust gas;
• a diluter provided upstream of the analyzer in the sampling channel;
• a recirculation channel that branches from a branch point set between the analyzer and the diluter in the sampling channel, joins the diluter, and directs part of the exhaust gas flowing through the sampling channel from downstream to upstream of the sampling channel;
• a pump that is provided in the recirculation channel to move the part of the exhaust gas flowing through the sampling channel toward the analyzer from downstream to upstream of the sampling channel by returning the part of the exhaust gas from the branch point to the diluter through the recirculation channel;
• an additional channel that is connected to the recirculation channel or the sampling channel and through which a calibration gas or a purge gas flows;
• and
• an opening and closing mechanism provided in the additional channel, wherein an additional flow rate as a flow rate of the calibration gas or the purge gas introduced from the additional channel into the recirculation channel is larger than an analysis gas flow rate as a flow rate of a gas introduced into the analyzer, and wherein the recirculation channel is provided with a first filter that captures the particulate matter.