Claims:We Claim:
1. A low pressure circuit (10) in a fuel injection system, said low pressure circuit (10) comprising:
an air filter (12);
a supercharger (14) coupled downstream from said air filter (12), said supercharger (14) adapted to receive air supplied from said air filter (12);
an electrical throttle valve (16) coupled downstream from said supercharger (14), said electrical throttle valve (16) adapted to receive air from said supercharger (14) and deliver compressed air to an engine (18); and
a hydrocarbon injector (20) in flow communication downstream from said engine (18), said hydrocarbon injector (20) adapted to deliver pressurized fuel to an exhaust gas flow path (22) of the fuel injection system.

2. The low pressure circuit (10) in the fuel injection system in accordance with Claim 1 further comprising a NOX storage catalyst (24) coupled downstream from said hydrocarbon injector (20), said hydrocarbon injector (20) adapted to cause regeneration of said NOX storage catalyst (24).

3. The low pressure circuit (10) in the fuel injection system in accordance with Claim 2 further comprising a diesel particulate filter (26) coupled downstream from said NOX storage catalyst (24), said hydrocarbon injector (20) adapted to cause regeneration of said diesel particulate filter (26).
, Description:Field of the invention
[0001] This invention relates to a fuel injection system and more particularly to a low pressure circuit in the fuel injection system.

Background of the invention
[0002] IN Patent Application Number 201741009627 describes a low pressure circuit in a fuel injection system. The low pressure circuit comprises a rail and a low pressure pump in flow communication upstream from the rail. The low pressure pump is adapted to supply pressurized fuel to the rail. A hydrocarbon injector is in flow communication downstream from the rail, the rail adapted to supply pressurized fuel to the hydrocarbon injector to facilitate delivering pressurized fuel to an exhaust gas flow path of the fuel injection system.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a schematic diagram of a low pressure circuit in a fuel injection system.

Detailed description of the invention
[0004] Figure 1 illustrates a low pressure circuit 10 in a fuel injection system. The low pressure circuit 10 comprises an air filter 12 and a supercharger 14 coupled downstream from the air filter 12, the supercharger 14 adapted to receive air supplied from the air filter 12. An electrical throttle valve 16 is coupled downstream from the supercharger 14, the electrical throttle valve 16 adapted to receive air from the supercharger 14 and deliver compressed air to an engine 18. A hydrocarbon injector 20 is in flow communication downstream from the engine 18, the hydrocarbon injector 20 adapted to deliver pressurized fuel to an exhaust gas flow path 22 of the fuel injection system.
[0005] The low pressure circuit 10 further comprises an air filter 12. A supercharger 14 is coupled in flow communication with the air filter 12 and delivers pressurized air to an electrical throttle valve 16. The electrical throttle valve 16 is in flow communication with the supercharger 14 and prevents backflow of air to the supercharger 14.
[0006] From the electrical throttle valve 16, the air is expanded and delivered to a fuel injector of the engine via a supply path 17. The air with fuel is combusted in the engine 18 to release exhaust gas to the exhaust gas flow path 22. The products of combustion from the engine 18 is channeled to the exhaust gas flow path 22 and subsequently vented to the atmosphere. A hydrocarbon injector 20 is in flow communication with the exhaust gas flow path 22.
[0007] More specifically, the hydrocarbon injector 20 is in flow communication with the exhaust gas flow path 22 and injects fuel into the exhaust gas flow path 22. Pressurized fuel is supplied from a fuel supply path (not shown) to the hydrocarbon injector 20, from where it is injected into the exhaust gas flow path 22. An engine control unit (not shown) is in electronic communication with the hydrocarbon injector 20 via a control flow path. When it is required to inject fuel from the hydrocarbon injector 20 into the exhaust gas flow path 22, the engine control unit transmits an electronic signal to the hydrocarbon injector 20, thereby regulating the quantity and time duration for which fuel is required to be injected into the exhaust gas flow path 22. The fuel that is injected by the hydrocarbon injector 20 into the exhaust gas flow path 22 reacts with the exhaust gas that is discharged from the engine 18 to produce exhaust gas at an elevated temperature. The exhaust gas at the elevated temperature is channeled to the NOX storage catalytic chamber 24 where it facilitates regeneration of the NOX storage catalytic chamber 24. Therein, the exhaust gas is channeled to the diesel particulate filter 26 for filtering the exhaust gas before venting the exhaust gas out of the fuel injection system.
[0008] A working of the low pressure circuit 10 in the fuel injection system is described as an example. Pressurized fuel is supplied to the hydrocarbon injector 20 via a fuel flow path. When the NOX storage catalyst 24 is required to be regenerated, fuel is delivered from the hydrocarbon injector 20. When it is required to deliver fuel from the hydrocarbon injector 20, the engine control unit transmits an electronic signal to the hydrocarbon injector 20. The electronic signal is a function of the time duration for which fuel is required to be injected by the hydrocarbon injector 20 into the exhaust gas flow path 22. Based on the electronic signal that is received, the hydrocarbon injector 20 opens for a specified time duration, thereby allowing the required quantity of fuel to be injected into the exhaust gas flow path 22. The fuel that is injected by the hydrocarbon injector 20 inside the exhaust gas flow path 22 reacts with the exhaust gas flowing through the exhaust gas flow path 22, thereby generating products of combustion. These products of combustion are at an elevated temperature than the temperature of the exhaust gas flowing through the exhaust gas flow path 22. The elevated temperature of exhaust gas in the NOX storage catalyst 24 that flows through the exhaust gas flow path 22 causes regeneration of the NOX storage catalyst 24. When it is required to stop the injection of fuel into the exhaust gas flow path 22 by the hydrocarbon injector 20 once the NOX storage catalyst 24 is regenerated, the engine control unit disconnects the electronic signal to the hydrocarbon injector 20, thereby stopping the injection of fuel inside the exhaust gas flow path 22.
[0009] The above mentioned process is extremely effective in regeneration of the NOX storage catalyst without the aid of an external heating means such as an electrical heater positioned within the NOX storage catalyst 24. It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with regard to leverage and dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the claims.