Claims:We Claim:
1. A method of controlling fuel injection quantity in a fuel injection system, said fuel injection system comprising a low pressure circuit comprising at least a fuel tank, a fuel filter and a density sensor, and a high pressure circuit comprising at least a high pressure pump and a fuel injector, said method comprising:
receiving (100), by a control unit density of fuel from said density sensor;

determining (102), by said control unit an actual energizing time for said fuel injector;

comparing (104), by said control unit from a data map a theoretical energizing time corresponding to said density of fuel;

comparing (106), by said control unit said theoretical energizing time with said actual energizing time; and

correcting (108), by said control unit said actual energizing time to match said theoretical energizing time.

2. The method of claim 1, wherein said density sensor is located in the high pressure circuit of said fuel injection system.
, 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 the field of fuel injection system.

Background of the invention
[0002]In a fuel injection system, fuel injection quantity from the fuel injector is important for the engine to develop rated power and to meet emission requirements. Fuel injection from the fuel injector is controlled by the energizing. The energizing time has to be precise for optimum performance of the engine. Energizing time defines the time period for which the fuel injector is kept open. Energizing time is affected by density of fuel. Depending upon the density of fuel the energizing time may vary and this may affect the engine from developing rated power.

[0003]Prior art patent application US4252097 discloses an apparatus and method for supplying a predetermined volume of liquid fuel to a cylinder of a diesel engine is provided. A storage tank stores a column of the liquid fuel in a storage area. A position sensor transmits an analog signal proportional to the height of the fuel in the tank. A pressure transducer disposed at the bottom of the storage area transmits an analog signal corresponding to the static fluid pressure at the bottom of the storage area. A temperature transducer disposed along a fuel rail transmits an analog temperature signal to an electronic fuel injection computer. The computer converts the analog height signal, the analog temperature signal and the analog pressure signal into digital values and mathematically divides the resulting digital values of height and pressure to obtain a digital value for the fuel density. A programmed ROM of the computer produces an output binary signal representative of a predetermined viscosity based on the instantaneous values of the temperature and the density of the fuel over a range of values of the density and the temperature. The ROM generates a three-dimensional surface representing values of viscosity based upon the temperature and the density. The output binary signal of the ROM is used by the computer through a diesel output control to control a metering solenoid of a fuel injector which injects fuel into a cylinder of the engine.

Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[0005] FIG. 1 illustrates a method of controlling fuel injection quantity in a fuel injection system.
Detailed description of the embodiments
[0006] FIG. 1 illustrates a method of controlling fuel injection quantity in a fuel injection system. The fuel injection system comprises a low pressure circuit comprising at least a fuel tank, a fuel filter and a density sensor, and a high pressure circuit comprising at least a high pressure pump and a fuel injector. The method comprises receiving (100), by a control unit density of fuel from the density sensor. An actual energizing time of the fuel injector is determined 102 by the control unit. The control unit compares 104 from a data map a theoretical energizing time corresponding to the density of fuel, the theoretical energizing time is then compared 106 with the actual energizing time. The actual energizing time is corrected 108 by the control unit with the theoretical energizing time. In an embodiment the density sensor may be located in the high pressure circuit of the fuel injection system.

[0007]The working of the above mentioned method will be explained in further detail. The above mentioned method makes use of density of fuel as an input and then changes the energizing time of the fuel injector so that the energizing time is according to the density of fuel. The density of fuel is received 100 by the control unit from the density sensor. The density sensor may be located in the low pressure circuit of the fuel injection system. The low pressure circuit is a part of fuel injection system from the fuel tank to the high pressure pump. The density thus received is then used as a reference for arriving at the energizing time. The density of fuel is in the range 0.82 to 0.835 Kg/L. For the purpose of better understanding let us consider that the density of fuel as received by the density sensor to be 0.83 kg/L. For this density of fuel it assumed that the theoretical energizing time to be X1 seconds. The control unit now determines 102 the actual energizing time. It is assumed that the actual energizing time to be X2 seconds. Now, the value of X3 seconds is compared with X2 seconds. If there is a variation between the values of X3 and X2 seconds then this implies that correction in the energizing time needs to be employed to maintain rated power of the engine. The difference between the theoretical and the actual energizing time is because of mixing of fuels with different densities, change in the quality of fuel, fuels mixing with impurities. The actual energizing time is corrected 108 by the control unit to match with the theoretical energizing time. This ensures that the energizing time is as prescribed for a fuel for a particular density (in this case 0.83 kg/l).

[0008]By the use of the above mentioned it is now possible to have correction in energizing time of the fuel injector by taking into account density of fuel. This is required as the fuel quantity changes from one filling station to another and hence the fuel density also changes. With this the energizing time can be optimized for a particular fuel density thus achieving the rated engine power.

[0009] ‘Adapted’ or ‘arranged’, in the context of the instant disclosure, refers to the technical capability or the technical capacity of a component, in relation to which the term ‘adapted’ or ‘arranged’ is used, to carry out or executed a specified action or actions, upon the requirement of the specified action or actions to be carried out or executed. Moreover, the usage of the term ‘adapted’ or ‘arranged’ here, is in reference with the normal technical capability or technical capacity of the component, imparted by the design or the structure or the composition of the component, and not in reference with any special or extraneous capability or capacity, beyond the scope of the normal technical capability or technical capacity. Therefore there is a need to address this problem.

[0010]It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention in terms of the type of fuel injection system. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.