Exhaust gas purification apparatus

An exhaust gas purification apparatus comprising:

• a catalyst unit provided in an exhaust pipe of an engine;
• adsorption means which carries an adsorbent for adsorbing a harmful component of an exhaust gas, said adsorption means being provided in said exhaust pipe downstream of said catalyst unit;
• a first exhaust gas flow path for forming a flow of said exhaust gas which does not pass through said adsorption means, said first exhaust gas flow path being provided in said exhaust pipe downstream of said catalyst unit;
• recirculation flow pipes for connecting a second flow path of said adsorption means and an upstream side of said catalyst unit;
• flow controlling means provided between said recirculation flow pipes so as to be actuated by pulsations of said exhaust gas, said flow controlling means controlling a flow in said recirculation flow pipes only in one direction from said adsorption means to said catalyst unit;
• exhaust-gas-flow-path change-over means which can selectively change over a course of flowing said exhaust gas between said adsorption means and said first exhaust gas flow path;
• and
• control means for controllably turning said exhaust-gas-flow-path change-over means to a first position where said exhaust gas is made to flow through said adsorption means when an engine is in a cool state and to a second position where said exhaust gas is made to flow through said first exhaust gas flow path when said engine is in a warm state,
• wherein a position of said flow controlling means between said recirculation flow pipes is predetermined so that said flow controlling means is operated by a differential pressure by a phase difference between pulsations of said exhaust gas applied to said flow controlling means from said upstream side of said catalyst unit and applied to said flow-controlling means from said second flow path of said adsorption means.

An exhaust gas purification apparatus comprising:

• a catalyst unit provided in an exhaust pipe of an engine;
• adsorption means which carries an adsorbent for adsorbing a harmful component of an exhaust gas, said adsorption means being provided in said exhaust pipe downstream of said catalyst unit;
• a first exhaust gas flow path for forming a flow of said exhaust gas which does not pass through said adsorption means, said first exhaust gas flow path being provided in said exhaust pipe downstream of said catalyst unit;
• recirculation flow pipes for recirculating said harmful component of said exhaust gas adsorbed by said adsorption means to an upstream side of said catalyst unit;
• exhaust-gas-flow-path change-over means provided downstream of said adsorption means, which means can selectively switch a course of flowing said exhaust gas between a second flow path of said adsorption means and said first exhaust gas flow path;
• rectifying means provided upstream of said adsorption means, which means can rectify a flow of said exhaust gas flowing into said adsorption means to thereby uniformly distribute a flow-in velocity of said exhaust gas;
• and
• control means for controllably turning said exhaust-gas-flow-path change-over means to a first position where said exhaust gas is made to flow through said adsorption means when said engine is in a cool state and to a second position where said exhaust gas is made to flow through said first exhaust gas flow path when said engine is in a warm state.

An exhaust gas purification apparatus comprising:

• a catalyst provided in an exhaust pipe of an internal combustion engine;
• a container provided downstream of said catalyst with an inlet and an outlet for an exhaust gas;
• an adsorbent disposed in said container for adsorbing a harmful component contained in said exhaust gas of said internal combustion engine;
• a lateral flow passage defined in said container and disposed laterally of said adsorbent for passing through said exhaust gas introduced into said container;
• recirculation means for recirculating said harmful component adsorbed by said adsorbent to an upstream side of said catalyst;
• and
• change-over means, disposed in said container, for switching a flow of said exhaust gas introduced into said container to a side of said adsorbent or to a side of said lateral flow passage, wherein said change-over means is set to switch said flow of said exhaust gas so as to cause said exhaust gas to pass through said adsorbent when a temperature of said exhaust gas of said internal combustion engine is lower than a predetermined level and to cause said exhaust gas to pass through said lateral flow passage and not to pass through said adsorbent when said temperature of said exhaust gas of said internal combustion engine is higher than said predetermined level, and said adsorbent is exposed to said exhaust gas passing through said lateral flow passage when said temperature of said exhaust gas of said internal combustion engine is higher than said predetermined level.