System and processes for storing an additive and injecting it into the exhaust gases of an engine

Abstract

System for storing an additive solution and injecting it into the exhaust gases of an internal combustion engine, the system comprising a tank for storing the additive and a rotary pump, a metering valve and an injector which are separate devices, this system making it possible to meter and inject the additive solution into the exhaust gases as is, without diluting it with a gas. In this system, the pump outlet pressure is regulated by adjusting the rotational speed of the pump. Process using such a system.

1 . A system for storing an additive solution and injecting it into the exhaust gases of an internal combustion engine, said system comprising a tank for storing the additive and a rotary pump, a metering valve and an injector which are separate devices, this system making it possible to meter and inject the additive solution into the exhaust gases as it is, without diluting it with a gas, wherein the pump outlet pressure is regulated by adjusting the rotational speed of the pump. 
   
   
       2 . The system according to  claim 1 , wherein the pump discharges an excess of additive solution (i.e. a higher flow than that of the injector), and wherein the system comprises a return line equipped with a pressure-limiting device that enables the excess of solution to be returned to the tank. 
   
   
       3 . The system according to  claim 2 , wherein the pressure-limiting device is a restrictor which may be combined with a non-return valve. 
   
   
       4 . The system according to  claim 2 , wherein the pressure-limiting device is a calibrated spring or diaphragm valve. 
   
   
       5 . The system according to  claim 2 , wherein the pressure-limiting device is located downstream of the metering valve, in a line that enables the flow of additive not consumed by this valve to be returned to the tank. 
   
   
       6 . The system according to  claim 2 , wherein the pressure-limiting device is located downstream of the injector, in a line that enables the flow of additive not consumed by this injector to be returned to the tank. 
   
   
       7 . The system according to  claim 6 , comprises comprising a by-pass line that enables the flow of additive not consumed by the injector to be brought back upstream of the metering valve instead of to the tank when the temperature of the additive in the tank exceeds a threshold value. 
   
   
       8 . The system according to  claim 6 , comprising a purge valve with a gas inlet upstream of the pump. 
   
   
       9 . The system according to any one of the preceding claims  claim 1 , comprising a filter located between the tank and the pump. 
   
   
       10 . The system according to  claim 2 , wherein the pump, the pressure-limiting device and the metering valve are integrated into a flange which is connected to the injector via an injection line. 
   
   
       11 . A process for storing an additive solution and injecting it into an exhaust pipe of an internal combustion engine, said process consisting in conveying the solution stored in a tank to an injector using a rotary pump and a metering valve, injector, pump and metering valve being separate devices, and in injecting this solution into the exhaust pipe as is, without diluting it with a gas, the pump outlet pressure being regulated by adjusting its rotational speed. 
   
   
       12 . The process according to  claim 11 , wherein the pump discharges an excess of additive solution (i.e. a higher flow than that of the injector), and wherein this excess is returned to the tank via a return line equipped with a pressure-limiting device. 
   
   
       13 . The process according to  claim 11 , wherein the metering valve is opened for an adjustable duration and frequency, and wherein the amount of additive solution is metered by adjusting this duration and this frequency electronically.