Secondary air supply device and method for internal combustion engine

Abstract

A secondary air supply device for an internal combustion engine includes an air pump that can be actuated while the internal combustion engine is stopped. An air passage connects the air pump and an exhaust passage of the internal combustion engine and an air supply control section controls the air pump so as to switch the air pump from a stopped state to an actuation state a predetermined time after the internal combustion engine is stopped. The secondary air supply device utilizes an air supply system including the air pump and the air passage to supply air to the exhaust passage.

1 . A secondary air supply device for an internal combustion engine, comprising:
 an air pump that can be actuated while the internal combustion engine is stopped;   an air passage that connects the air pump and an exhaust passage of the internal combustion engine, wherein the secondary air supply device utilizes an air supply system including the air pump and the air passage to supply air to the exhaust passage; and   an air supply control section that controls the air pump so as to switch the air pump from a stopped state to an actuation state a predetermined time after the internal combustion engine is stopped.   
   
   
       2 . The secondary air supply device according to  claim 1 , wherein condensed water is produced in the air supply system during at least a portion of the predetermined time. 
   
   
       3 . The secondary air supply device according to  claim 1 , further comprising:
 a temperature acquisition section that acquires at least one temperature associated with cooling of the air supply system; and   a time setting section that sets the predetermined time based on the at least one temperature acquired by the temperature acquisition section.   
   
   
       4 . The secondary air supply device according to  claim 3 , wherein the temperature acquisition section acquires, as the temperature associated with the cooling, at least one of a passage wall temperature of the air passage or an ambient temperature. 
   
   
       5 . The secondary air supply device according to  claim 4 , wherein the temperature acquisition section acquires a passage wall temperature, and wherein the passage wall temperature is estimated based on at least one of a load of the internal combustion engine or a rotational speed of the internal combustion engine. 
   
   
       6 . The secondary air supply device according to  claim 4 , wherein the at least one temperature is estimated based on stored data relating to the secondary air supply device. 
   
   
       7 . The secondary air supply device according to  claim 2 , further comprising:
 a drain section that can drain condensed water collected in the air pump; and   a drain control section that controls the drain section such that the condensed water collected in the air pump can be drained before the air supply control section switches the air pump from the stopped state to the actuation state.   
   
   
       8 . The secondary air supply device according to  claim 7 , further comprising:
 a valve that opens and closes the air passage, wherein   the drain control section individually controls the valve and the air pump so as to actuate the air pump with the air passage closed by the valve.   
   
   
       9 . A secondary air supply device according to  claim 1 , wherein the predetermined time is variable, and wherein the air supply control section determines the predetermined time based upon at least one condition relating to an operating condition of the internal combustion engine or the air supply system. 
   
   
       10 . A secondary air supply device according to  claim 1 , wherein the predetermined time is variable, and wherein the air supply control section determines the predetermined time based upon at least one of a temperature of the air passage or an ambient temperature. 
   
   
       11 . A secondary air supply device according to  claim 1 , further comprising a valve that opens and closes the air passage, and wherein the air supply control section opens the valve at the same time as or after the air pump is switched to the activation state. 
   
   
       12 . A control method for a secondary air supply device for an internal combustion engine that utilizes an air supply system to supply air to an exhaust passage of the internal combustion engine, the air supply system including an air pump that can be actuated while the internal combustion engine is stopped, and an air passage that connects the air pump and the exhaust passage, the control method comprising:
 determining whether a predetermined time has elapsed after the internal combustion engine is stopped; and   after the predetermined time, controlling the air pump to switch the air pump from a stopped state to an actuation state.   
   
   
       13 . The control method according to  claim 12 , wherein
 the air pump is switched to the actuation state after opening a drain valve to drain condensed water collected in the air pump and closing the drain valve.   
   
   
       14 . A secondary air supply device for an internal combustion engine, comprising:
 an air pump that can be actuated while the internal combustion engine is stopped;   an air passage that connects the air pump and an exhaust passage of the internal combustion engine, the secondary air supply device utilizing an air supply system including the air pump and the air passage to supply air to the exhaust passage; and   an air supply control means for controlling the air pump so as to switch the air pump from a stopped state to an actuation state a predetermined time after the internal combustion engine is stopped.   
   
   
       15 . A secondary air supply device for an internal combustion engine, comprising:
 an air pump that can be actuated while the internal combustion engine is stopped;   an air passage that connects the air pump and an exhaust passage of the internal combustion engine, the secondary air supply device utilizing an air supply system including the air pump and the air passage to supply air to the exhaust passage; and   an air supply control section that controls the air pump so as to switch the air pump from a stopped state to an actuation state after a condition relating to production of condensed water in the air supply system is satisfied after the internal combustion engine is stopped.   
   
   
       16 . The secondary air supply device according to  claim 15 , further comprising:
 a temperature acquisition section that acquires at least one temperature associated with cooling of the air supply system, and   wherein the condition relating to production of condensed water is based on the acquired at least one temperature.   
   
   
       17 . The secondary air supply device according to  claim 16 , wherein
 the temperature acquisition section acquires as the temperature associated with the cooling at least one of a passage wall temperature of the air passage or an ambient temperature.   
   
   
       18 . The secondary air supply device according to  claim 16 , wherein the condition relating to production of condensed water is satisfied when the at least one acquired temperature is lower than a predetermined temperature. 
   
   
       19 . The secondary air supply device according to  claim 16 , wherein the condition relating to production of condensed water is satisfied when a predetermined time has elapsed after the internal combustion engine is stopped, and wherein the predetermined time is variable and is determined by the air supply control section based on the acquired at least one temperature. 
   
   
       20 . The secondary air supply device according to  claim 15 , further comprising:
 a drain section that can drain condensed water collected in the air pump; and   a drain control section that controls the drain section such that the condensed water collected in the air pump can be drained before the air supply control section switches the air pump from the stopped state to the actuation state.   
   
   
       21 . The secondary air supply device according to  claim 20 , further comprising:
 a valve that opens and closes the air passage, wherein   the drain control section individually controls the valve and the air pump so as to actuate the air pump with the air passage closed by the valve.   
   
   
       22 . A secondary air supply device according to  claim 15 , further comprising a valve that opens and closes the air passage, and wherein the air supply control section opens the valve at the same time as or after the air pump is switched to the activation state. 
   
   
       23 . A secondary air supply device according to  claim 15 , wherein the condition relating to production of condensed water is based on at least one of a temperature of the air passage or an ambient temperature.