Claims:We claim:
1. A controller (102) for a gaseous fuel supply system (100) in a vehicle, said system (100) comprising a supply line (130) with a Shut-Off Valve (SOV) (110) positioned at a first end and a fuel injector (104) at a second end, a pressure regulator (114) is connected upstream of said SOV (110), said controller (102) is adapted to:
open said SOV (110) to allow passage of fuel to said supply line (130);
determine pressure of said fuel in said supply line (130) using a sensor (106), and
operate said SOV (110) in a manner to maintain pressure of said fuel in said supply line (130) within an operable pressure range of said fuel injector (104), if said determined pressure is above a threshold value.

2. The controller (102) as claimed in claim 1, detects a fault in said pressure regulator (114), upon detection of said determined pressure above said threshold value.

3. The controller (102) as claimed in claim 1, operates said SOV (110) based on time values stored in a calibration curve, said time values are determined based on at least one factor comprising a minimum required pressure for operation of the engine, a time taken for increase in pressure as soon as said SOV (110) is opened, a minimum opening/closing time of said SOV (110) and a time taken for decreasing the pressure during the engine operation and a maximum operating pressure of said fuel injector (104).

4. The controller (102) as claimed in claim 1, wherein said fuel is selected from a group comprising Compressed Natural Gas (CNG), Liquefied Petroleum Gas (LPG), bi-fuels and other gaseous fuels.

5. The controller (102) as claimed in claim 1, opens said SOV (110) when an engine of said vehicle is started.

6. A method for controlling a gaseous fuel supply system (100) of a vehicle, said system (100) comprising a supply line (130) with a Shut Off Valve (SOV) (110) positioned at a first end and a fuel injector (104) at a second end, a pressure regulator (114) is connected upstream of said SOV (110), said method comprising the steps of:
opening said SOV (110) to allow fuel passage into a supply line (130);
determining a pressure of said fuel in said supply line (130) using a sensor (106), and
operating closing and opening of said SOV (110) in manner to maintain pressure of said fuel in said supply line (130) within an operable pressure range of said fuel injector (104), if said determined pressure is above a threshold value.

7. The method as claimed in claim 6, further comprises detecting a fault in said pressure regulator (114) upon detecting said determined pressure above said threshold value.

8. The method as claimed in claim 6, wherein said SOV (110) is operated based on time values stored in a calibration curve, said time values are determined based on at least one factor comprising a minimum required pressure for operation of the engine, a time taken for increase in pressure as soon as said SOV (110) is opened, a minimum opening/closing time of said SOV (110), a time taken for decreasing the pressure during the engine operation and a maximum operating pressure for said fuel injector (104).

9. The method as claimed in claim 6, wherein said fuel is selected from a group comprising Compressed Natural Gas (CNG), Liquefied Petroleum Gas (LPG), bi-fuels and other gaseous fuels.

10. The method as claimed in claim 6, wherein opening said SOV (110) is performed when an engine of said vehicle is started.
, 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] The present invention relates to a controller and method for a gaseous fuel supply system of a vehicle.

Background of the invention:
[0002] According to a patent literature, US2014142832, a gaseous fuel system and method for an engine is disclosed. A vehicle method for gaseous fuel loss detection, including for each of a high and low pressure portion of a fuel system including a gaseous fuel, indicating degradation based on a loss of mass from the fuel system, the loss of mass based separately tracking fuel mass in each of the portions based respective temperatures and pressures at a first and second instance following an engine off condition. The method may utilize the respective pressures and temperatures to determine which portions of the fuel system are losing mass and further identify degradation of fuel system valves.

[0003] CNG systems used for automotive applications have electric Shut-OFF Valve (SOV) for safety. This SOV can be used anywhere in the pressure lines and its operation can be controlled by a controller such as Electronic Control Unit (ECU). This SOV will be normally closed when the engine is not running and should be opened only when the engine is running. However to perform the diagnosis, the SOV can be opened for maximum of two seconds before the engine is started and should be closed after that.

[0004] In some systems, the volume of the low pressure rail will be higher than the operating pressure of the CNG injectors. The Pressure-Temperature (PT) sensor will be mounted on the injector rail. Any leakage of the pressure before the SOV will not be identified by the pressure sensor. If a high pressure is accumulated before the SOV and the SOV is opened, all the accumulated pressure will flow in to the injector rail. So whenever this accumulated pressure inside rail is higher than the operating pressure of the CNG injector, the injector will not work and may not start the vehicle. This can also mislead to the faulty injector diagnosis or component failure. This condition can happen whenever the vehicle is parked for a long time and incase the Mechanical Pressure Regulator (MPR) is creating the leakage or in case of MPR failure. The only way to avoid this failure is release the accumulated pressure inside the rail into the environment by opening the rail, which is not practical.

Brief description of the accompanying drawings:
[0005] An embodiment of the disclosure is described with reference to the following accompanying drawing,
[0006] Fig. 1 illustrates a gaseous fuel injection system, according to an embodiment of the present invention, and
[0007] Fig. 2 illustrates a method for operating a Shut-OFF Valve (SOV) in the gaseous fuel injection system, according to the present invention.

Detailed description of the embodiments:
[0008] Fig. 1 illustrates a gaseous fuel injection system, according to an embodiment of the present invention. The system 100 comprises a controller 102 to operate a Shut-OFF Valve (SOV) 110 for a vehicle. The system 100 further comprises a supply line 130 connected between a pressure regulator 114 and a fuel injector 104. The SOV 110 is positioned at a first end of the supply line 130 and the fuel injector 104 is positioned at a second end. The pressure regulator 114 is connected upstream of the SOV 110. The system 100 further comprises a fuel tank 118 storing pressurized gaseous fuel and connected to the pressure regulator 114 through flow control valves. Necessary check valves 120 and 112 are used to control the system pressure at different places. The pressure at upstream side of the pressure regulator 114 is monitored by a pressure sensor 116. A filler connector 122 enables the filing of fuel tank 118 through external sources. A filter 108 is optionally connected in the supply line 130.

[0009] The controller 102 is connected to the sensor 106, the pressure sensor 116, the SOV 110, the fuel injector 104 and the like. The controller 102 is adapted to open the SOV 110 to allow passage of fuel to the supply line 130. The controller 102 then determines pressure of the fuel in the supply line 130 using a sensor 106. The sensor 106 is a pressure sensor. The controller 102 then operates the SOV 110 in a manner to maintain pressure of the fuel in the supply line 130 within an operable pressure range of the fuel injector 104, if the determined pressure is above a threshold value. The operable pressure range implies a minimum pressure and a maximum pressure required for the functioning of the fuel injector 104.

[0010] The SOV 110 is opened when an engine of the vehicle is started. Alternatively, the SOV 110 is opened during diagnosis performed before the engine is started, or right after the engine is shut down.

[0011] In accordance to another embodiment of the present invention, the controller 102 detects a fault in the pressure regulator 114 or any abnormality in the supply line 130, upon detection of the determined pressure above the threshold value. The threshold value is the minimum pressure of the fuel in the supply line 130 which is required for the operation of the fuel injector 104.

[0012] The supply line 130 is a low pressure line of the gaseous fuel supply system 100. The supply line 130 may in the form of a flexible tube or a rail. Further, at least one fuel injector 104 is connected to the second end of the supply line 130. Plurality of fuel injectors 104 are also possible to be used. The line upstream of the pressure regulator 114 connected to the fuel tank 118 is the high pressure line.

[0013] The fuel is selected from a group comprising Compressed Natural Gas (CNG), Liquefied Petroleum Gas (LPG), bifuels and other gaseous fuels.

[0014] An example of working of the present invention is explained. Consider the SOV 110 is closed and there is an internal leakage in the pressure regulator 114. Because of the internal leakage, there is an overpressure in the supply line 130 between the pressure regulator 114 and the SOV 110. The pressure keeps building before the SOV 110 until its maximum volume. Since the sensor 106 is mounted nearer to the supply line 130 after the SOV 110, the increase in pressure before the SOV 110 is not detected. Now, when the SOV 110 is opened, the pressurized fuel accumulated before SOV 110 starts to flow into the supply line 130. If the volume of the supply line 130 is lesser to accommodate the volume of the pressurized fuel, an issue in starting the vehicle rises, since the pressure inside the supply line 130 is higher than the operating pressure of the fuel injector 104. The fuel injector 104 fails to open because of the higher pressure and no fuel is injected and hence the vehicle does not start.

[0015] Now as per the present invention, the SOV 110 is used as a pressure regulator 114. The SOV 110 is electrically operated solenoid valve and is not limited to the same. The controller 102 controls the opening/closing of the SOV 110 by monitoring/determining the pressure read from the sensor 106. An example of controlling the SOV 110 is provided. Whenever the engine is started for the first time, the controller 102 delays the opening of the SOV 110 until the pressure reaches the minimum value and monitors the increase in pressure once the SOV 110 is opened. If the pressure increases more than operating pressure of the fuel injector 104, the controller 102 closes the SOV 110 immediately and waits until it reaches minimum value (Due to the fuel consumption by the engine). This step continues until the pressure becomes steady.

[0016] In accordance to an embodiment of the present invention, the controller 102 operates/regulates the opening and closing of the SOV 110 based on the calibration curves/table stored in a memory element of the controller 102. The calibration curves is selected based on the pressure determined by the sensor 106. The time values of the calibration curves are empirically calibrated/determined based on at least one factor comprising, a minimum required pressure for operation of the engine, a time taken for increase in pressure as soon as the SOV 110 is opened, minimum opening/closing time of the SOV 110, a time taken for decreasing the pressure during the engine operation, a maximum operating pressure for the fuel injector 104, and the like. The calibration curves/table is an array where the data such as time is stored to control the opening/ closing of the SOV 110. The time value is stored based on the behavior/variation of the pressure in the supply line 130, which is further affected by at least one aforementioned factors.

[0017] Example: Suppose when the SOV 110 is opened and if the pressure in the supply line increases to 6 bar (consider 5 bar as threshold value), then the controller 102 immediately closes the SOV 110 due pressure increased over the threshold value. Now assuming (only for explanation purpose), if the engine is running at 3000 RPM, the time taken for reducing the pressure from 6 bar to 3 bar is around 3 seconds, and 2 seconds if the engine is running at 4000 RPM. These values of time are stored in the calibration curves/table. Now, in real time scenario, once the SOV 110 closes at 6 bar, the controller 102 waits up to 3 seconds or 3 bar pressure in supply line 130, whichever occurs first, and then opens the SOV 110 again. The operating pressure range of the fuel injector 104 is assumed to be 5 bar to the 9 bar. The optimal pressure is 5 bar, however the pressure detected in the supply line is 6 bar. Since, the pressure is within the operable pressure range, the fuel injector 104 is operated at 6 bar, and thus pressure reduces as the fuel is injected into the engine. Now, when the pressure again goes below the 5 bar, the SOV 110 is opened and the pressure is maintained in the operable pressure range of the fuel injector 104. Optionally, the pressure is given priority over the time stored in the calibration curve, to control the SOV 110. This example must not be understood in limiting manner.

[0018] Fig. 2 illustrates a method for controlling a gaseous fuel injection system, according to the present invention. The system 100 comprises the supply line 130 with the SOV 110 positioned at the first end and the fuel injector 104 at the second end. The pressure regulator 114 is connected upstream of the SOV 110. The pressure regulator 114 regulates and supplies a low pressure fuel from the fuel tank 118, which stores fuel at high pressure, to the supply line 130. The method comprises the steps of, a step 202 comprising opening the SOV 110 to allow fuel passage into the supply line 130. A step 204 comprises determining the pressure of the fuel in the supply line 130 using the sensor 106. A step 206 comprises operating closing and opening the SOV 110 in manner to maintain pressure of the fuel in the supply line 130 within the operable pressure range of the fuel injector 104, if the determined pressure is above a threshold value. The operable pressure range implies a minimum pressure and a maximum pressure required for the functioning of the fuel injector 104.

[0019] The method further comprises detecting a fault in the pressure regulator 114 or a fault in the supply line 130 upon detecting the determined pressure above the threshold value.

[0020] The opening of the SOV 110 is performed when an engine of the vehicle is started. Further, the method of operating the SOV 110 is performed based on time values calibrated and stored in the calibration curves/table. The time values are calibrated/determined based on at least one factor comprising a minimum required pressure for operation of the engine, a time taken for increase in pressure as soon as the SOV 110 is opened, minimum opening/closing time of the SOV 110, a time taken for decreasing the pressure during the engine operation and a maximum operating pressure for the fuel injector 104.

[0021] The fuel is selected from a group comprising Compressed Natural Gas (CNG), Liquefied Petroleum Gas (LPG), bi-fuels and other gaseous fuels.

[0022] The present invention provides an advanced strategy for the over pressure protection for CNG/LPG automotive system. The invention of over pressure protection by controlling the SOV 110 is applicable to any automotive CNG/LPG system, both Original Equipment (OE) and retrofit where the SOV 110 is used on the low pressure side. It is applicable for both mono-fuel and bi-fuel systems. The present invention enables the vehicle to function normally, but with an indication of fault. Alternatively, the vehicle is run till a specific distance such as to a nearest service station. The present invention enables operation of the fuel injector 104 by regulating the pressure in the low pressure line beside detecting the over pressure.

[0023] 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.