Exhaust gas purification apparatus and exhaust gas purification method

Abstract

An exhaust gas purification apparatus which is installed in a flow channel of an exhaust gas discharged from an engine, includes: a first purification device that purifies one component contained in the gas; a heating device that heats the purification device to a predetermined temperature in a period from before the engine is started to a first point in time that is after the engine is started; control device that controls an air-fuel ratio of the gas so as to obtain a air-fuel ratio suitable for purifying the one component in a period from the time when the engine is started to a point in time that is on or after a time at which the purification device is heated to the predetermined temperature; and an adsorption device that communicates with the downstream of the first purification device and adsorbs another component contained in the gas.

1 . An exhaust gas purification apparatus installed in an exhaust pipe serving as a flow channel of an exhaust gas discharged from an engine, comprising:
 a first purification device that purifies at least one component from among a plurality of components contained in the exhaust gas;   a heating device that heats the first purification device to a predetermined temperature in at least part of a period from before the engine is started to a first point in time that is after the engine is started;   an air-fuel ratio control device that controls an air-fuel ratio of the exhaust gas so as to obtain a first air-fuel ratio suitable for the first purification device to purify the one component in at least part of a period from the time when the engine is started to a second point in time that is on or after a time at which the first purification device is heated to the predetermined temperature; and   an adsorption device that communicates with the exhaust pipe and at least partially adsorbs another component from among the plurality of components.   
   
   
       2 . The exhaust gas purification apparatus according to  claim 1 , wherein the air-fuel ratio control device controls an air-fuel ratio of the exhaust gas so as to obtain a first air-fuel ratio suitable for purifying one component from among the plurality of components in a period from the time when the first purification device is heated to an activation temperature thereof to the second point in time. 
   
   
       3 . The exhaust gas purification apparatus according to  claim 1 , further comprising an air-fuel detection device that detects an air-fuel ratio of the exhaust gas flowing in the exhaust pipe, wherein the air-fuel ratio control device feedback-controls the air-fuel ratio of the exhaust gas based at least on the detected air-fuel ratio. 
   
   
       4 . The exhaust gas purification apparatus according to  claim 3 , wherein
 the second point in time is a point in time at which activation of the air-fuel ratio detection device is started, and   the air-fuel ratio control device feedback-controls the air-fuel ratio within an active period of the air-fuel ratio detection device that starts at the second point in time.   
   
   
       5 . The exhaust gas purification apparatus according to  claim 1 , further comprising a desorption state specifying device that specifies a desorption state of the other component from the adsorption device, wherein the second point in time is established according to the specified desorption state of the other component. 
   
   
       6 . The exhaust gas purification apparatus according to  claim 1 , further comprising a second purification device that purifies another component adsorbed by the adsorption device. 
   
   
       7 . The exhaust gas purification apparatus according to  claim 1 , wherein the adsorption device communicates with the exhaust pipe downstream of the first purification device. 
   
   
       8 . The exhaust gas purification apparatus according to  claim 7 , wherein the first purification device also functions as the second purification device and comprises a restricting device that restricts the release of the exhaust gas from the exhaust pipe downstream of the first purification device and the adsorption device in the exhaust pipe, and a recirculation device that desorbs the adsorbed other component and recirculates the other component via a recirculation channel to a zone upstream of the first purification device, while the release of the exhaust gas is restricted by the restricting device. 
   
   
       9 . The exhaust gas purification apparatus according to  claim 8 , further comprising a supply device that supplies secondary air to the first purification device via the recirculation channel. 
   
   
       10 . The exhaust gas purification apparatus according to  claim 9 , further comprising a desorption state specifying device that specifies a desorption state of the other component from the adsorption device, wherein the supply device supplies the secondary air according to the specified desorption state of the other component. 
   
   
       11 . The exhaust gas purification apparatus according to  claim 9 , further comprising an OSC state specifying device that specifies an OSC state of the first purification device that also functions as the second purification device, wherein the supply device supplies the secondary air according to the specified OSC state. 
   
   
       12 . The exhaust gas purification apparatus according to  claim 9 , further comprising an internal pressure specifying device that specifies a pressure inside the exhaust pipe in a state in which the release of the exhaust gas is restricted by the restriction device, wherein the supply device regulates the supplied amount of the secondary air according to the specified internal pressure. 
   
   
       13 . The exhaust gas purification apparatus according to  claim 9 , wherein the heating device heats the first purification device according to the amount of the secondary air supplied by the supply device. 
   
   
       14 . The exhaust gas purification apparatus according to  claim 6 , wherein the second purification device purifies the other component in a period during which the engine is stopped. 
   
   
       15 . The exhaust gas purification apparatus according to  claim 1 , wherein the first point in time is a point in time at which the exhaust gas is practically not discharged from the engine. 
   
   
       16 . The exhaust gas purification apparatus according to  claim 1 , wherein the one component is nitrogen oxide, and
 the first air-fuel ratio is an air-fuel ratio on a rich side from a theoretical air-fuel ratio of the engine.   
   
   
       17 . An exhaust gas purification apparatus installed in an exhaust pipe serving as a flow channel of an exhaust gas discharged from an engine, comprising:
 first purification means for purifying at least one component from among a plurality of components contained in the exhaust gas;   heating means for heating the first purification means to a predetermined temperature in at least part of a period from before the engine is started to a first point in time that is after the engine is started;   air-fuel ratio control means for controlling an air-fuel ratio of the exhaust gas so as to obtain a first air-fuel ratio suitable for the first purification means to purify the one component in at least part of a period from the time when the engine is started to a second point in time that is on or after a time at which the first purification means is heated to the predetermined temperature; and   adsorption means for communicating with the exhaust pipe downstream of the first purification means and at least partially adsorbing another component from among the plurality of components.   
   
   
       18 . An exhaust gas purification method for a purification device that purifies at least one component from among a plurality of components contained in an exhaust gas discharged from an engine, comprising:
 heating the purification device to a predetermined temperature in at least part of a period from before the engine is started to a first point in time that is after the engine is started;   controlling an air-fuel ratio of the exhaust gas so as to obtain a first air-fuel ratio suitable for purifying the one component in at least part of a period from the time when the engine is started to a second point in time that is on or after a time at which the purification device is heated to the predetermined temperature; and   at least partially adsorbing another component from among the plurality of components.