Claims:We Claim

1. A method for assessing a useful life of a fuel injector, the fuel injector coupled downstream from a common rail, a rail pressure sensor in flow communication with the common rail and the fuel injector, an engine control unit in electronic communication with the rail pressure sensor and adapted to receive an electronic signal from the rail pressure sensor, said method comprising:
sensing 10 a pressure variation of fuel in the common rail by means of the rail pressure sensor;
transmitting 20 the pressure variation of fuel in the common rail by the rail pressure sensor to the engine control unit;
comparing 30 the transmitted pressure variation of fuel in the common rail with a threshold pressure variation of fuel by the engine control unit;
transmitting 40 an error signal by the engine control unit to a user based on the comparison of the transmitted pressure variation of fuel in the common rail with the threshold pressure variation of fuel, thereby indicating an end of a useful life of the fuel injector.

2. The method for assessing a useful life of a fuel injector in accordance with Claim 1 wherein comparing 30 the transmitted pressure variation of fuel in the common rail with the threshold pressure variation of fuel by the engine control unit further comprises determining 50 a deviation in the transmitted pressure variation of fuel in the common rail with the threshold pressure variation of fuel.

3. The method for assessing a useful life of a fuel injector in accordance with Claim 2 wherein the deviation in the transmitted pressure variation of fuel in the common rail with the threshold pressure variation of fuel above a predetermined value is indicative of an end of a useful life of the fuel injector.

, Description:Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001] This invention relates to a method for assessing a useful life of a fuel injector by means of a rail pressure sensor.

Background of the invention
[0002] US Patent Number 5492099 A describes an apparatus and method for sensing a failure of an hydraulically-actuated electronically-controlled fuel injector in an internal combustion engine. An electronic controller senses the pressure of the hydraulic actuator fluid prior to injection and samples the pressure throughout a subsequent injection cycle. If the samples show an oscillation in the pressure of the hydraulic actuator fluid, then the injector has fired. Otherwise, the injector has failed.

Brief description of the accompanying drawing
[0003] Figure 1 illustrates a block diagram of a method for assessing a useful life of a fuel injector in one embodiment of the invention.

Detailed description of the embodiments
[0004] Figure 1 illustrates a method for assessing a useful life of a fuel injector, the fuel injector coupled downstream from a common rail, a rail pressure sensor in flow communication with the common rail and the fuel injector, an engine control unit in electronic communication with the rail pressure sensor and adapted to receive an electronic signal from the rail pressure sensor. The method comprises sensing 10 a pressure variation of fuel in the common rail by means of the rail pressure sensor, and transmitting 20 the pressure variation of fuel in the common rail by the rail pressure sensor to the engine control unit. The method further comprises comparing 30 the transmitted pressure variation of fuel in the common rail with a threshold pressure variation of fuel by the engine control unit, and transmitting 40 an error signal by the engine control unit to a user based on the comparison of the transmitted pressure variation of fuel in the common rail with the threshold pressure variation of fuel, thereby indicating an end of a useful life of the fuel injector.

[0005] The method for assessing a useful life of a fuel injector comprises a fuel injector that is defined downstream from a common rail. More specifically, the fuel injector is in flow communication downstream from the common rail and receives pressurized fuel that is delivered from the common rail. A rail pressure sensor is in flow communication with the common rail and senses the pressure variation of the fuel that is stored in the common rail. An engine control unit is in electronic communication with the rail pressure sensor and receives the electronic signal that is transmitted from the rail pressure sensor, that is indicative of the pressure variation of the fuel that is stored in the common rail. When the electronic signal that is indicative of the pressure variation of the fuel that is stored in the common rail is transmitted from the rail pressure sensor to the engine control unit exceeds a threshold pressure variation of fuel that is pre-programmed in the ECU, an error signal is transmitted by the engine control unit to a user, thereby notifying the user of an end of a useful life of the fuel injector. More specifically, when the fuel injector is functioning normally, the rail pressure sensor transmits a first electronic signal to the engine control unit that is the threshold pressure variation of the fuel that is stored in the common rail. When the fuel injector is faulty or when its useful life has expired, the rail pressure sensor transmits a second electronic signal to the engine control unit that is indicative of the pressure variation of the fuel that is stored in the common rail. If the pressure variation of the fuel that is stored in the common rail deviates from the threshold pressure variation of fuel that is pre-programmed in the ECU, the fuel injector is determined to be faulty by the engine control unit. Therefore, the deviation between the first electronic signal and the second electronic signal by the rail pressure sensor notifies to the user the end of the useful life of the fuel injector.

[0006] The method comprises sensing 10 a pressure variation of fuel in the common rail by means of the rail pressure sensor. Therein, the pressure variation of fuel in the common rail is transmitted 20 as an electronic signal by the rail pressure sensor to the engine control unit. Therefore, the engine control unit determines the pressure variation of fuel in the common rail from the received electronic signal. The method further comprises comparing 30 the transmitted pressure variation of fuel in the common rail with a threshold pressure variation of fuel that is pre-programmed and stored in the engine control unit by a user. In the exemplary embodiment, the engine control unit compares the transmitted pressure variation of the fuel that is in the common rail with the pre-programmed threshold pressure variation of the fuel that is pre-programmed and stored in the engine control unit. On comparing the transmitted pressure variation of fuel in the common rail with the pre-programmed threshold pressure variation of fuel within the engine control unit, a deviation of the transmitted pressure of fuel in the common rail with the threshold pressure variation of fuel within the engine control unit is determined.

[0007] Therein, an error signal is transmitted by the engine control unit to a user based on the comparison of the transmitted pressure variation of fuel in the common rail with the threshold pre-programmed pressure variation of fuel. More specifically, when the deviation of the transmitted pressure variation of fuel in the common rail with the threshold pressure variation of fuel is greater than a predetermined value, it is indicative of an end of a useful life of the fuel injector. Therein, an error signal is transmitted by the engine control unit to a user, thereby notifying the user of the end of the useful life of the fuel injector. The error signal may be displayed in the form of an error message on the instrument cluster in the dashboard of the vehicle. The advantage of the invention is that a user can determine the end of the useful life of the fuel injector merely by determining the pressure variation of the fuel in the common rail. Therefore, no transducer is required to be installed in the fuel injector to assess that the fuel injector is not functioning normally.

[0008] 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 dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the scope of the claims.