Air-pollution preventive arrangement

Abstract

An air-pollution preventive arrangement for use with an internal combustion engine for motor vehicles, adapted to reduce the concentrations of noxious compounds such as unburned hydrocarbons and carbonmonoxides contained in the engine exhaust gases. The arrangement comprises a thermal reactor for primarily re-combusting the exhaust gases and a catalytic converter for secondarily recombusting the exhaust gases passed from the thermal reactor so as to oxidize the residual unburned compounds. An air injection unit supplies additional air which is admixed, in a limited proportion, to the exhaust gases entering the thermal reactor to aid in the primary re-combustion of the exhaust gases therein. The noxious unconsumed hydrocarbons and carbon-monoxides are thus converted into innocuous compounds at efficiencies which are far higher than those attained where the thermal reactor or the catalytic converter is employed independently. Such additional air may also be admixed to the exhaust gases entering the catalytic converter which is located downstream of the thermal reactor, whereby the re-combustion efficiencies of the reactor and converter are maintained at high levels throughout varying driving conditions of the motor vehicle. The arrangement may also comprise a second catalytic converter which is adapted to reduce nitrogen oxides in the exhaust gases.

What is claimed is: 
     
       1. An air pollution preventive arrangement for use with an engine for a motor vehicle having an exhaust system through which exhaust gases emitted from the engine are discharged, comprising: a thermal reactor mounted on said exhaust system and located posterior to exhaust ports of said exhaust system for primarily re-combusting unconsumed hydrocarbons and carbon monoxides contained in said exhaust gases;   at least one catalytic converter mounted on said .[.exhuast.]. .Iadd.exhaust .Iaddend.system and located posterior to said thermal reactor for secondarily re-combusting the exhaust gases passed from said thermal reactor.   means for supplying additional air to said .[.exhuast.]. .Iadd.exhaust .Iaddend.system anterior to said thermal reactor and to said exhaust system anterior to said catalytic converter, comprising: a pneumatic pump;   a first passage leading from said pneumatic pump to said exhaust system anterior to said thermal reactor; and   a second passage leading from said pneumatic pump to said exhaust system anterior to said catalytic converter; and     means for controlling the amounts of said additional air to be supplied to said thermal reactor and said catalytic converter, respectively, comprising: a one-way check valve mounted on said first passage for preventing a reverse flow of the exhaust gases from said exhaust system upstream of said thermal reactor,   a device including a valve means mounted on and normally closing said second passsage, said valve means being caused to open said second passage when actuated; and   a combination of detector and switch means which is responsive to deceleration conditions of the motor vehicle for closing said valve means when said conditions are detected thereby.     
     
     
       2. An air preventive arrangement according to claim 1, in which said valve means comprises: a solenoid valve having a spring loaded armature and valve member, and in which said combination of detector and switch means comprises:   a normally closed switch connected to said solenoid valve to excite the solenoid valve when closed and   a detector for detecting said conditions for opening said switch when said conditions are detected thereby.   
     
     
       3. An air pollution preventive arrangement according to claim 2, in which said detector comprises: a diaphragm device having a spring loaded diaphragm member subjected to suctions drawn from an intake manifold of the engine and mechanically connected to said switch, said diaphragm member being biased by a spring action to a position in which said switch is closed and moved against said spring action to a position in which said switch is open when said suctions reach a predetermined level.   
     
     
       4. An air pollution preventive arrangement according to claim 2, in which said detector comprises: a mechanical linkage interconnecting said switch and a throttle valve of a carburetor of the engine, said linkage being normally held in a position to close said switch and moved to a position to open said switch when said throttle valve opening degree is less than a predetermined level.   
     
     
       5. An air-pollution preventive arrangement according to claim 2, in which said at least one catalytic converter includes a second catalytic converter mounted on said exhaust system and located intermediate between said thermal reactor and the first named catalytic converter, said second converter having mounted therein a catalyzer for deoxidizing nitrogen oxides contained in the exhaust gases passed from said thermal reactor.