Field of the invention:
[0001] The present invention relates to a controller to detect leakage in a gaseous fuel supply system for an engine of a vehicle. The present invention more particularly relates to determining leakage upon failure of a pressure sensor or in the system without the pressure sensor in a fuel rail.
Background of the invention:
[0002] According to a patent literature US2014142832, a gaseous fuel system and method for an engine is disclosed. The patent further discloses a method for gaseous fuel loss detection, including for each of a high and low pressure portion of a fuel system including a gaseous fuel. The method indicates degradation based on a loss of mass from the fuel system, the loss of mass based on separately tracking fuel mass in each of the portions based on 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] The state of the art Compressed Natural Gas (CNG) systems used for automotive applications comprises a pressure and temperature sensor mounted on the fuel rail / module or on the low pressure side of the system along with a pressure sensor at high pressure line, thereby increasing the cost and maintenance. [0004] Hence, there is a need for a system to detect leakage in fuel supply system in cost effective manner. Further, there is a need for a system to detect a leakage in fuel rail/ low pressure line without a pressure sensor. Still further, there is a need for a system to detect leakage in case of a failure of a pressure sensor in fuel supply system.
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 block diagram of a gaseous fuel supply system of a
vehicle, according to an embodiment of the present invention, and

[0007] Fig. 2 illustrates a flow diagram of a method for detecting leakage in a gaseous fuel supply system of a vehicle, according to the present invention.
Detailed description of the embodiments
[0008] Fig. 1 illustrates a block diagram of a gaseous fuel supply system of a vehicle, according to an embodiment of the present invention. The system 100 comprises a fuel tank 102, a high pressure line 104 which connects the fuel tank 102 to a pressure regulator 108. A high pressure sensor 106 is provided/mounted inside the high pressure line 104. A low pressure line 114 connects the pressure regulator 108 to a fuel rail 118. The fuel rail 118 is connected with at least one fuel injector 120. The low pressure line 114 may or may not be provided with a low pressure sensor 116, hence shown in dashed format.
[0009] The system 100 further comprises a controller 110 which is adapted to control/operate the pressure regulator 108 and at least one fuel injector 120. The controller 110 is further adapted to detect leakage in the gaseous fuel supply system 100 for an engine of the vehicle. The controller 110 checks to ensure or validates no leakage in high pressure line 104 during start of the engine. The controller 110 then opens the pressure regulator 108 to supply fuel to the low pressure line 114 from the high pressure line 104, in other words, the controller 110 regulates fuel flow. The controller 110 determines pressure variation or pressure value in the high pressure line 104 after opening the pressure regulator 108. The controller 110 then compares the pressure variation with a threshold variation or threshold value to detect a leakage in the low pressure line 114.
[0010] The controller 110 receives input signals from various sensors and gives output through the Input/ Output (I/O) interface 112. The controller 110 and its components are not explained as it is obvious for a person skilled in the art. [0011] The pressure variation in the presence of a leakage is already stored as a map in a memory element of the controller 110. Also, the pressure variation for various/different pressures of tank or the high pressure line 104 is mapped. When there is a leakage in the low pressure line 114, the controller 110 looks the map of the pressure variation and compares with a threshold variation. If the threshold

variation is reached, the controller 110 detects a leakage in the low pressure line
114.
[0012] In accordance to an embodiment of the present invention, the controller
110 detects the leakage in the gaseous fuel supply system 100, where there is no
low pressure sensor 116 and/or there is no temperature sensor, mounted in the low
pressure line 114.
[0013] In accordance to an embodiment of the present invention, the controller
110 detects the leakage of the gaseous fuel supply system 100, where the low
pressure sensor 116 is provided for the low pressure line 114. The controller 110
detects the leakage when the low pressure sensor 116 in the low pressure line 114
fails or gets abnormal. Further, the controller 110 detects the leakage even when the
low pressure sensor 116 in the low pressure line 114 is normal, as a double check
or cross check.
[0014] The controller 110 detects the leakage in the low pressure line 114 using
the high pressure sensor 106 mounted in the high pressure line 104 or in the fuel
tank 102. There is no low pressure sensor 116 in the low pressure line 114.
[0015] In accordance to another embodiment of the present invention, the
controller 110 further comprises a temperature correction map stored in the memory
element to adapt the pressure variation based on the current atmospheric
temperature. The vehicle already comprises a temperature sensor or one is included
in the system 100.
[0016] The gaseous fuel is selected from a group comprising a Compressed
Natural Gas (CNG), Liquefied Natural Gas (LNG) and the like.
[0017] An example scenario is described and the same must not be understood
in a limiting sense. In case of overnight leakage in the low pressure line 114 due to
internal leakage in pressure regulator 108, without a low pressure sensor 116 and/or
a temperature sensor, it is difficult to detect the leakage. To identify the overnight
leakage in the low pressure line 114 or the fuel rail 118, before starting the vehicle,
the controller 110 performs./executes below steps: once the ignition of the vehicle
is turned ON, the controller 110 closes both shut OFF valves of the fuel tank 102
and the pressure regulator 108. The controller 110 record the pressure value of the

fuel tank 102 in the memory element. The controller 110 opens the shut OFF value of the pressure regulator 108. If there is an overnight leakage in the low pressure line 114, the pressure in the fuel tank 102 or the high pressure line 104 decreases by a certain value. The controller 110 compares the same or the pattern of pressure variation and identifies the overnight leakage. The same is indicated to the passenger/ driver of the vehicle.
[0018] Fig. 2 illustrates a flow diagram of a method for detecting leakage in a gaseous fuel supply system of a vehicle, according to the present invention. The method for detecting leakage in the gaseous fuel supply/delivery system 100 of the
' vehicle comprises, a step 202 comprising confirming/validating no leakage in high pressure line 104 upon starting of the engine by the controller 110. A step 204 comprises opening pressure regulator 108 to supply fuel to the low pressure line 114, when there is no leakage in the high pressure line 104. A next step 206 comprises determining variation in the pressure in the high pressure line 104 after the pressure regulator 108 is open. A step 208 comprises comparing the pressure variation/value with a threshold variation/value to detect a leakage in the low pressure line 114.
[0019] The method is applied for the system 100 where there is no low pressure sensor 116 in the low pressure line 114.
' [0020] The method is applied when there is a failure of the low pressure sensor 116 in the low pressure line 114 of the fuel supply system 100. Alternatively, the method is performed even though the low pressure sensor 116 in the low pressure line 114 is functioning normally to double check.
[0021] The method further comprises correcting the pressure variation based on current atmospheric temperature by using a correction map stored in a memory element of the controller 110.
[0022] The controller 110 and the method is provided to detect the overnight leakage in the low pressure line 114 or rail for the system 100 without the low pressure sensor 116 and the temperature in the low pressure line 114. The present
' invention is applicable to any automotive CNG system 100, both from Original Equipment Manufacturers (OEM) and retrofit vehicles with or without the low

pressure sensor 116 in the low pressure line 114. For system 100 with low pressure sensor 116, the controller 110 and the method is used as a backup or secondary method (to check plausibility of primary method and in case of failure of the low pressure sensor 116) to identify low pressure leakage. It is applicable for mono-fuel and bi-fuel system 100, i.e. one gaseous fuel and other liquid fuel such as petrol, diesel, etc. The present invention provides a cost efficient detection in case of no low pressure sensor 116.
[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.

We claim:
1. A controller (110) to detect leakage in a gaseous fuel supply system (100)
for an engine of a vehicle, said system (100) comprising a fuel tank (102),
a high pressure line (104) connected from said fuel tank (102) to a pressure
regulator (108), a high pressure sensor (106) mounted in said high pressure
line (104), a low pressure line (114) connected from said pressure regulator
(108) to at least one fuel injector (120), said controller (110) controls said
pressure regulator (108) and said at least one fuel injector (120),
characterized in that:
said controller (110) further adapted to:
validate no leakage in said high pressure line (104) during start of
said engine;
operate said pressure regulator (108) to supply fuel to said low
pressure line (114);
determine pressure variation in said high pressure line (104) after
operating said pressure regulator (108), and
compare said pressure variation with a threshold variation to detect
a leakage in said low pressure line (114).
2. The controller (110) as claimed in claim 1 is retrofit to vehicles with gaseous fuel supply system (100).
3. The controller (110) as claimed in claim 1, wherein said system (100) comprises a low pressure sensor (116) in said low pressure line (114).
4. The controller (110) as claimed in claim 1, wherein said leakage is detected upon failure of a low pressure sensor (116) in said low pressure line (114).
5. The controller (110) as claimed in claim 1, further corrects said pressure variation based on a current atmospheric temperature by using a temperature correction map stored in a memory element.

6. The controller (110) as claimed in claim 1, wherein said gaseous fuel is selected from a group comprising a Compressed Natural Gas (CNG), Liquefied Natural Gas (LNG) and the like.
7. A method for detecting leakage in a gaseous fuel supply system (100) of a vehicle, said method comprising the steps of:
validating no leakage in a high pressure line (104) upon starting of
an engine by a controller (110);
operating a pressure regulator (108) to supply fuel to a low pressure
line (114), when there is no leakage in said high pressure line (104);
determining variation in pressure in said high pressure line (104)
after opening said pressure regulator (108), and
comparing said pressure variation with a threshold variation to
detect a leakage in said low pressure line (114).
8. The method as claimed in claim 7 is applied when there is a failure of a low pressure sensor (116) in said low pressure line (114) of said fuel supply system (100).
9. The method as claimed in claim 7 is applied for a gaseous fuel supply system (100) without a low pressure sensor (116) in said low pressure line (114).
10. The method as claimed in claim 7, further corrects said pressure variation based on current atmospheric temperature by using a correction map stored in a memory element of said controller (110).