Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed:
[0001] Field of the invention:
The invention is related to a device for detecting a fault in a main circuit and a method thereof.
[0002] Background of the invention:
The ECU (Electronics Control Unit) is used to control the engine/ transmission / Brake loads in the vehicle. The ECU reads all the necessary operating data required for controlling and regulating the engine/ transmission / Brake loads using sensors, switches as well as data from the bus systems. Based on the type of sensor used, it will be either a 3 pin (Supply, Signal and return) or 2 pin (Signal and return). During a normal operation, the ECU is supplied from battery through main relay or directly from battery. The battery voltage is in turn converted to different supply voltages (Ex:5V) using the voltage regulator. This is supplied externally to the sensor. The return (ground) line from the sensor is given to the ECU pin which is connected to the common ground plane of the ECU. Any Short circuit at the ground Pin can cause huge current to flow through the pin. This may lead to corresponding failures like a damage of the ECU ground pin, wiring harness and connectors or to the functionalities in the ECU cannot be guaranteed and may lead to undesired operating conditions like sudden stop, unintended acceleration etc.

[0003] Brief description of the accompanying drawings:
An embodiment of the disclosure is described with reference to the following accompanying drawing,
[0004] Figures 1(a), 1(b) illustrates a device for detecting a fault in a main circuit according to one embodiment of the invention; and
[0005] Figure 2 illustrates a flow chart of a method for detecting a fault in a main circuit according to the present invention.
Detailed description of the embodiments:
[0006] Figures 1(a), 1(b) illustrates a device for detecting a fault in a main circuit in accordance with1 the present invention. The main circuit 12 comprising at least one sensing element 14 connected to a control unit 16. The device 10 comprises a sub circuit 18 connected to each of the at least one sensing element 18 and a common switch 20 connected to the at least one sensing element 18 via corresponding the sub circuit 18. The control unit 16 detects the fault in the at least one sensing element 18 upon sensing a flow of a high current via the corresponding sub circuit 18.
[0007] Further the construction of the main circuit and the device and their components are explained in detail. According to one embodiment of the invention, the main circuit 12 is used in a vehicle. However, the application of the main circuit 12 is not limited to the vehicle but can be any other product where the sensing elements 14 are connected and controlled via the control unit 16. The control unit 16 is chosen from a group of control units comprising a microcontroller, a microprocessor, a digital circuit, an integrated chip, an application specific chip and the like. The sensing element 14 mentioned in the present application is any type of sensing element that is used to detect at least one parameter of the vehicle, wherein one such parameter can be engine speed, vehicle speed, gear ratio, current, voltage and the like. Multiple sensing elements 14 are connected to the control unit 16 for monitoring a smooth operation of the vehicle.
[0008] The device comprising the sub circuit 18 and the common switch 20 is connected to the sensing element 14 and the control unit 16 set present in the main circuit 12. According to one embodiment of the invention, the device 10 is made as an integral part of the main circuit 12. According to one embodiment of the invention, the device 10 is connected externally to the main circuit 12. Each of the sub circuit 18 is connected between the sensing element 14 and the common switch 20. The sub circuit 18 comprises a resistor 22 and a diode 24. Each of the sensing element 14 have a corresponding sub circuit 18.
[0009] The connections from each of the sub circuit 18 is connected to the common switch 20. The common switch 20 is chosen from a group of common switches comprising an integrated gate bipolar transistor (IGBT), a MOSFET and the like. According to one embodiment of the invention, the fault is battery to the ground fault. However, the fault can be any other type of the fault that is known to a person skilled in the art.
 
[0010] Figure 2 illustrates a flow chart of a method for detecting a fault in a main circuit according to the present invention. The main circuit 12 comprises a control unit 16 connected to at least one sensing element 14. In step S1, a sub circuit 18 to each of the sensing element 14 present in the main circuit 12 is connected. In step S2, each of the sub circuit 18 corresponding to the sensing element 14 is connected to a common switch 20. In step S3, the common switch 20 is opened upon flow of a high current when the fault in the main circuit 12 is occurred. In step S4, the flow of the high current via at least one the sub circuit is detected when the common switch is opened and when the fault is occurred.
[0011] The method is explained in detail. The sensing elements 14 present in the main circuit 12 will be in an active state detecting multiple parameters of the vehicle. The control unit 16 is adapted to control at least one operation of the sensing elements 14 present in the main circuit 12. During a fault (for instance, a battery to ground fault) in any one of the sensing elements 14, a high current will flow into the ground through the common switch 20, thus opening the common switch 20. With the flow of the high current via the common switch 20, the state of the common switch 20 changes from the close state to open state as shown in the figure 1(a). The arrow in the diagram indicates the flow of high current.
[0012] When the common switch 20 is opened due to the flow of the high current, the current will get divert to another path. The high current then flows through the resistor 22 of the sub circuit to the ground. The resistor 22 of the sub circuit 18 will be related to that sensing element 14 where the fault is occurred. The control unit 16 upon sensing the flow of the high current in the sub circuit 18, detects the faulty/malfunctioning sensing element 14 in the main circuit 12 as shown in the figure 1(b). The arrow in the diagram indicates the flow of high current.
[0013] With the above device 10 and the method, the fault in the main circuit 12 can be easily identified. The malfunctioning of the sensing element 14 can be identified for the replacement or repair for a smooth operation of the vehicle. Replacement of the main circuit is not required as the sensing element 14 is sufficient to be replaced. With a smaller number of components, the fault can be identified and thus providing a low-cost solution.

[0014] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. 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.
, Claims:We claim: -
1. A device (10) for detecting a fault in a main circuit (12), said main circuit (12) comprising at least one sensing element (14) connected to a control unit (16);
characterized in that:
said device (10) comprising:
- a sub circuit (18) connected to each of said at least one sensing element (14);
- a common switch (20) connected to said at least one sensing element (14) via corresponding said sub circuit (18);
said control unit (16) detects said fault in said at least one sensing element (14) upon sensing a flow of a high current via said corresponding said sub circuit (18).
2. The device (10) as claimed in claim 1, wherein said sub circuit (18) is connected between said at least one sensing element (14) and said common switch (20).
3. The device (10) as claimed in claim 3, wherein said sub circuit (18) comprises a resistor (22) and a diode (24) connected to said common switch (20).
4. The device (10) as claimed in claim 1, wherein said fault is a battery to ground short circuit fault.
5. The device (10) as claimed in claim 1, wherein said high current flows via said resistor (22) to a ground of said sub circuit (18) when said common switch (20) is in an open position and when said fault has been occurred.
6. The device (10) as claimed in claim 1, wherein said device (10) is made as an integral part of said main circuit (12).
7. A method of detecting a fault in a main circuit (12), said main circuit (12) comprising at least one sensing element (14) connected to a control unit (16);
said method comprising:
- connecting a sub circuit (18) to each of said sensing element (14) present in said main circuit (12);
- connecting each of said sub circuit (18) corresponding to said sensing element (14) to a common switch (20);
- opening of said common switch (20) upon flow of a high current when said fault in said main circuit (12) is occurred;
- detecting said flow of said high current via at least one said sub circuit (18) when said common switch (20) is opened and when said fault is occurred.