Claims:We Claim:
1. A method for detecting clogging in a filter of a pressure control valve in a common rail, said common rail located upstream to an engine, and comprising at least:
a pressure sensor,
said method comprising:
detecting (100) by said pressure sensor the pressure of fuel in said common rail;

comparing (102) by a control unit, said detected pressure with a target pressure for a given value of current supplied to said common rail;

detecting (104) whether a deviation between said detected pressure and said target pressure exceeds a threshold value; and

displaying (106) said deviation on a display device of a vehicle upon the deviation exceeding said threshold value.
2. The method of claim 1, further comprising alerting a user of a vehicle when said deviation exceeds said threshold value.
, Description:Field of the invention
[0001] This invention relates to the field of common rail in a fuel injection system.

Background of the invention
[0002] A common rail in a fuel injection system stores fuel under pressure before the fuel is delivered to the injectors. The common rail comprises a pressure control valve and a pressure sensor. The pressure control valve (PCV) has a filter crimped to it. The function of this filter is to purify some of the impurities present in the fuel that is stored in the rail. The pressure inside the rail is controlled by supplying and varying the magnitude of current supplied. For a particular value of pressure to be maintained, the corresponding value of current is stored in what is called as a data map in the electronic control unit (ECU).The presence of impurities in fuel will lead to clogging of pressure control valve, and hence the pressure detected by the pressure sensor will not be accurate. For example, for a current of 900mA if the corresponding pressure to be maintained is 800bar as per the data map, then in case the PCV is clogged for currently supply of 900mA there might be a deviation in the pressure achieved in the common rail. If the deviation between the actual pressure and the achieved pressure is more, then it may lead to problems like improper injection of fuel into the engine cylinders.

Brief description of the accompanying drawing
[0003] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

[0004] FIG. 1 illustrates method for detecting clogging in a filter of a pressure control valve in a common rail.

Detailed description of the embodiments
[0005] FIG. 1 illustrates method for detecting clogging in a filter of a pressure control valve in a common rail. The common rail is located upstream to an engine and comprises at least a pressure sensor. The method comprises detecting (100) the pressure of fuel in said common rail by the pressure sensor, comparing (102) by a control unit, the detected pressure with target pressure for a given value of current supplied to the common rail, detecting (104) whether a deviation between the detected pressure and said target pressure exceeds a threshold value and displaying (106) the deviation on a display device of a vehicle upon the deviation exceeding the threshold value. The deviation, in this context, refers to a difference between the detected pressure and said target pressure.

[0006] During working, the common rail receives fuel from the high pressure pump, this fuel is stored in the common rail under pressure before it is released to the cylinder via the injector. Current is supplied to the rail for controlling the pressure. The magnitude of current depends upon the pressure at which fuel needs to be delivered from the rail and into the injector. The pressure control valve that is present in the common rail is electronically controlled and regulates the pressure in the rail. In case, the pressure of fuel in the rail exceeds beyond a certain value, then the pressure control valve is actuated, and then the PCV opens a backflow path for the fuel to flow from the rail into the fuel tank. It is observed that, the particulates present in the fuel cause filter of the pressure control valve to clog. This leads to malfunction of the pressure control valve (PCV). In the proposed method, a control unit monitors the pressure in the common rail for a particular value of current supplied. The magnitude of pressure that is detected by the pressure sensor is compared with a target pressure for a given value of current supplied to the common rail. The control unit then detects whether the deviation between the detected pressure and the target pressure exceeds a threshold value. This deviation upon exceeding a threshold value, is then displayed on a display device. The display may be in be in the form of reading, a lamp, or an indicator. A user of the vehicle is thus alerted about clogging of filter in the PCV, and hence corrective actions can be taken to prevent PCV malfunction and thereby boosting engine performance. In case the user does not take corrective action, then an alert in the form an audio alarm may also be given. Also, an alert may be sent to the nearest service station and the defect can be logged in a database for that particular vehicle. With this the issue of clogging of filter in PCV can be displayed to the user of the vehicle and also an alert can be used in case the user does take suitable precautions to rectify the filter in the PCV.

[0007] With the proposed method, PCV seat wear due to particulates can be avoided. Also, with the proposed method there is possibility of early detection of clogged filter of PCV thereby obviating deterioration of engine performance.

[0008] 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 design of number of connectors used in the fuel distributor block. 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.