Method and apparatus for reducing hydrocarbon emissions for an internal combustion engine

Claim 1

A method for reducing hydrocarbon emissions during a cold-starting phase of an internal combustion engine with an exhaust system including an exhaust conduit for discharging the exhaust gas from said engine and a first catalytic converter arranged in the exhaust system close to the engine and an adsorber with a sorbent which adsorbs hydrocarbons below a desorption temperature and desorbs them above the desorption temperature, arranged downstream of said first catalytic converter in a bypass conduit to said exhaust conduit, said exhaust system having a second catalytic converter arranged in said exhaust conduit downstream of said bypass conduit and means for controlling the exhaust gas flow through said bypass conduit and said exhaust conduit, the steps comprising, below an operating temperature of said first catalytic converter and below the desorption temperature of said adsorber, conducting the exhaust gas through said bypass conduit and said adsorber, below the operation temperature of said first catalytic converter and above the desorption temperature of said adsorber, closing the bypass conduit, above the operation temperature of said first catalytic converter and above the desorption temperature of said adsorber passing at least part of the exhaust gas through the bypass conduit and the adsorber for the desorption of the hydrocarbons, and closing said bypass conduit when the operating temperature of said first catalytic converter has been reached, at least until the operating temperature of said second catalytic converter has been reached.

Claim 2

A method for reducing hydrocarbon emissions during a cold-starting phase of an internal combustion engine with an exhaust system including an exhaust conduit for discharging the exhaust gas from said engine and a first catalytic converter arranged in the exhaust system close to the engine and an adsorber with a sorbent which adsorbs hydrocarbons below a desorption temperature and desorbs them above the desorption temperature, arranged downstream of said first catalytic converter in a bypass conduit to said exhaust conduit, said exhaust system having a second catalytic converter arranged in said exhaust conduit downstream of said bypass conduit and means for controlling the exhaust gas flow through said bypass conduit and said exhaust conduit, the steps comprising, below an operating temperature of said first catalytic converter and below the desorption temperature of said adsorber, conducting the exhaust gas through said bypass conduit and said adsorber, below the operation temperature of said first catalytic converter and above the desorption temperature of said adsorber, closing the bypass conduit, above the operation temperature of said first catalytic converter and above the desorption temperature of said adsorber passing at least part of the exhaust gas through the bypass conduit and the adsorber for the desorption of the hydrocarbons, and closing said bypass conduit when the operating temperature of said first catalytic converter has been reached, at least until the operating temperature of said second catalytic converter has been reached.

Claim 6

An apparatus for reducing hydrogen emissions from an internal combustion engine having an exhaust conduit, a bypass conduit for bypassing a portion of said exhaust conduit, an adsorber arranged in said bypass conduit, said adsorber including an adsorbent capable of adsorbing hydrocarbons below a desorption temperature thereof and of desorbing hydrocarbons above said desorption temperature, means for controlling exhaust gas flow selectively through the bypassed portion of said exhaust conduit or through said bypass conduit and the adsorber arranged therein, a first catalytic converter arranged in said exhaust conduit close to said engine, a second catalytic converter arranged in said exhaust conduit downstream of said bypass conduit, and means for cooling said exhaust gas on its path from said first catalytic converter to said adsorber, said exhaust gas conduit being insulated between said engine and said first catalytic converter to avoid exhaust gas heat losses before the exhaust gas reaches said first catalytic converter, said means for controlling the exhaust gas flow being adapted to conduct said exhaust gas through said bypass conduit as long as said first catalytic converter has not reached operating temperature for removing hydrocarbons from the exhaust gas of said engine in said adsorber.

Claim 7

An apparatus for reducing hydrogen emissions from an internal combustion engine having an exhaust conduit, a bypass conduit for bypassing a portion of said exhaust conduit, an adsorber arranged in said bypass conduit, said adsorber including an adsorbent capable of adsorbing hydrocarbons below a desorption temperature thereof and of desorbing hydrocarbons above said desorption temperature, means for controlling exhaust gas flow selectively through the bypassed portion of said exhaust conduit or through said bypass conduit and the adsorber arranged therein, a first catalytic converter arranged in said exhaust conduit close to said engine, a second catalytic converter arranged in said exhaust conduit downstream of said bypass conduit, and means for cooling said exhaust gas on its path from said first catalytic converter to said adsorber, said exhaust gas conduit being insulated between said engine and said first catalytic converter to avoid exhaust gas heat losses before the exhaust gas reaches said first catalytic converter, said means for controlling the exhaust gas flow being adapted to conduct said exhaust gas through said bypass conduit as long as said first catalytic converter has not reached operating temperature for removing hydrocarbons from the exhaust gas of said engine in said adsorber.