Claims:We claim:

1. A control unit (130) to determine status of a manual Shut-off valve (SOV) (104) in a gaseous fuel supply system (100) of a vehicle, said system (100) comprises a tank (102) storing said gaseous fuel, said tank (102) in connection with a High Pressure (HP) line (110) through said manual SOV (104), an electronic SOV (106) and a pressure sensor (114), said HP line (110) connected to a Low Pressure (LP) line (120) through a pressure regulator (116), and said LP line (120) connected to a fuel injection unit (134), said control unit (130) adapted to
measure a current pressure of said HP line (110) during ignition ON condition of said vehicle;
compare said current pressure with a previous pressure accessible from a memory element (132) of said control unit (130);
monitor a decrease of said current pressure in said HP line (110) upon start of said engine, based on a result of said comparison, and
determine a status of said manual SOV (104) when said current pressure decreases below an expected pressure.

2. The control unit (130) as claimed in claim 1, wherein said previous pressure is pressure of said HP line (110) measured at an end of a previous drive cycle of said vehicle.

3. The control unit (130) as claimed in claim 1, wherein said expected pressure is selected based on said current pressure of said HP line (110).

4. The control unit (130) as claimed in claim 1, wherein said control unit (130) determines said status of said manual SOV (104) in a closed position when an actual rate of decrease of pressure decreases below a threshold rate, and consequently provides a signal to alert a driver for opening said manual SOV (104).

5. The control unit (130) as claimed in claim 1, wherein said control unit (130) provides a signal to alert a driver for opening said manual SOV (104).

6. A method for determining a status of a manual Shut-Off Valve (SOV) (104) in a gaseous fuel supply system (100) of a vehicle, said system (100) comprises a tank (102) storing said gaseous fuel, said tank (102) in connection with a High Pressure (HP) line (110) through said manual SOV (104), an electronic SOV (106) and a pressure sensor (114), said HP line (110) connected to a Low Pressure (LP) line (120) through a pressure regulator (116), and said LP line (120) connected to a fuel injection unit (134), said method comprising the steps of:
measuring a current pressure of said HP line (110) during ignition ON condition of said vehicle;
comparing said current pressure with a previous pressure, said previous pressure accessible from a memory element (132) of said control unit (130);
monitoring a decrease of said current pressure in said HP line (110) upon start of said engine, based on a result of said comparison, and
determining a status of said manual SOV (104) when said current pressure decreases below an expected pressure.

7. The method as claimed in claim 6, wherein said previous pressure is pressure of said HP line (110) measured during at an end of a previous drive cycle of said vehicle.

8. The method as claimed in claim 6, wherein said current pressure is measured before start of an engine of said vehicle.

9. The method as claimed in claim 6, wherein said expected pressure is selected based on said current pressure of said HP line (110).

10. The method as claimed in claim 6, comprises determining said manual SOV (104) in a closed position, and consequently providing a signal to alert a driver for opening said manual SOV (104).
, 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/ control unit and method to detect status of a manual Shut-OFF Valve (SOV) in a gaseous fuel supply system of a vehicle.

Background of the invention:
[0002] The state of the art CNG systems used for automotive applications have manual SOV or just valve for safety. The manual SOV does not have any electrical control from the control unit such as Engine Control Unit (ECU) and is directly operable by a driver. The manual SOV is used for safety purpose and is also used to close or open the high pressure flow which is stored in a tank storing the gaseous fuel.

[0003] In any gaseous fuel supply system, the manual SOV is mounted on the tank and then the High Pressure (HP) sensor which senses the pressure in the HP line. In case the driver has parked the vehicle overnight or for longer duration, as a safety precaution guidelines are given to close the manual SOV. So in case there are any fire accidents, the hazard caused will be minimum. However, if the driver forgets to open the manual SOV and starts the vehicle, only the pressure in the HP line is detected by the HP sensor, since the manual SOV is closed which restricts flow of pressurized fuel. Once the vehicle is started, the pressure in the HP line is used, and consequently the pressure in the HP line starts reducing drastically. The drastic reduction in high pressure is wrongly detected as leakage in the tank or the HP line. In a mono-fuel vehicle, this scenario leads to closing of the electronic SOVs and also the vehicle is restricted from starting until the vehicle is taken to service center for diagnosis and repair. In a Bi-fuel vehicle, the switch over to gaseous fuel is disabled until the leakage error is corrected. This causes unnecessary issues to the end user or the driver.

[0004] According to a patent US9745902 discloses a vehicle control apparatus and vehicle control method. If the pressure in a supply passage drops at a speed greater than a first determination speed in a state in which a first mode for supplying gas fuel to an internal combustion engine is selected, a control apparatus inhibits selection of the first mode. Then, the control apparatus switches from the first mode to a second mode, in energy other than gas fuel is used. In this state, if the pressure in the supply passage drops at a speed greater than a second determination speed, the control apparatus maintains the state in which the second mode is selected. If the pressure in the supply passage drops at a speed lower than the second determination speed, the control apparatus cancels the inhibition of selection of the first mode when it is detected that a manual on-off valve is opened.

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 supply system of a vehicle, according to an embodiment of the present invention, and
[0007] Fig. 2 illustrates a method for determining status of a manual SOV in a gaseous fuel supply system, according to an embodiment of the present invention.

Detailed description of the embodiments:
[0008] Fig. 1 illustrates a gaseous fuel supply system of a vehicle, according to an embodiment of the present invention. A control unit 130 to determine a status of the manual Shut-Off Valve (SOV) 104 in a gaseous fuel supply system 100 of a vehicle is provided. The system 100 comprises a tank 102 storing the gaseous fuel. The tank 102 is in connection with a High Pressure (HP) line 110 through the manual SOV 104, a first electronic SOV 106 and a pressure sensor 114. The HP line 110 connected to a Low Pressure (LP) line 120 through a pressure regulator 116, and the LP line 120 connected to a fuel injection unit 134. The system 100 further comprises a first check valve 112 positioned in the path of a filler connector 108. The filler connector 108 enables refilling of the tank 102 when empty. A second check valve 118 is provided in the LP line 120, through which the excess gaseous fuel is released to the atmosphere to maintain the pressure. The LP line 120 comprises an optional electronic SOV 122. The LP line 120 also comprises a filter 124 to prevent any impurities to flow towards the fuel injection unit 134. The fuel injection unit 134 is either a single injector or a common rail system or a fuel distributor block. The LP line 120 is also fit with other pressure sensor 126 and a temperature sensor 128 in connection with the control unit 130. The control unit 130 controls the fuel injection, and the control of the electronic SOVs 106 and 122.

[0009] In the system 100, the control unit 130 is adapted to measure a current pressure of the HP line 110 during ignition ON condition of the vehicle. The control unit 130 compares the current pressure with a previous pressure. The previous pressure is accessible from a memory element 132 of the control unit 130. The previous pressure is a pressure of the HP line 110 measured at an end of a previous drive cycle of the vehicle. Based on the result of the comparison, the control unit 130 monitors a decrease of the current pressure in the HP line 110 upon start of the engine for a time period. The control unit 130 determines a status of the manual SOV 104 when the current pressure decreases below an expected pressure. The status of the manual SOV 104 is detected to be closed, if the current pressure is below the expected pressure, whereas the status of the manual SOV 104 is detected to be open when the current pressure as per the expected pressure. Alternatively, an actual rate of decrease/reduction of the current pressure in the HP line 110 is compared against a threshold rate of decrease, to detect the state of the manual SOV 104.

[0010] . The previous drive cycle corresponds to the condition where the vehicle is shutting down after the driver has switched OFF the ignition. When the vehicle is shut down or switched OFF by the driver, the control unit 130 records/stores the pressure detected in the HP line 110 in the memory element 132.

[0011] The current pressure is the pressure, measured before start of the engine of the vehicle in a new drive cycle. More specifically, before the fuel is combusted inside the engine in the new drive cycle.

[0012] The comparison of the current pressure with the previous pressure is performed by the control unit 130 to check for leakage in the HP line 110. If the current pressure is same as the previous pressure or within a tolerance/threshold limit, then no leakage is detected. However, if current pressure is lesser than the previous pressure or outside the threshold limit, then the leakage is detected and the safety measure is initiated such as closing the electronic SOV 106 and 122 or other actions as known in the art.

[0013] After the comparison, the control unit 130 ascertains that there is no leakage in the HP line 110 and controls the supply of the fuel to the engine. Based on the result of the comparison, the control unit 130 monitors a reduction or decrease of the current pressure, via the signal received from the pressure sensor 114, in the HP line 110 upon start of the engine. Now, considering the manual SOV 104 is in closed position, the pressure detected in the HP line 110 by the control unit 130 starts decreasing as and when the fuel is combusted in the engine. Thus, the control unit 130 determines the status of the manual SOV 104 to be in closed position, when the current pressure decreases below the expected pressure. The expected pressure is selected based on the current pressure of the HP line 110. The expected pressure is either stored in the memory element 132 or is derived in real time.

[0014] According to the present invention, instead of detecting the condition of reduction of the current pressure as leakage, the control unit 130 is adapted to diagnose the reduction of the current pressure as false leakage based on the result of the comparison, and thereby eliminates the possibility of leakage in the HP line 110. With this information, the control unit 130 determines the manual SOV 104 to be in closed position, and consequently provides a signal to alert a driver for opening the manual SOV 104.

[0015] According to another embodiment, instead of using the expected pressure as parameter to detect status, the control unit 130 uses threshold rate of decrease of the current pressure to detect status of the manual SOV 104. The control unit 130 determines the actual rate of decrease of the current pressure in the HP line 110 upon start of the engine by using the pressure sensor 114. Considering the manual SOV 104 is in closed position, the pressure detected in the HP line 110 by the control unit 130 starts decreasing. The control unit 130 then detects a leakage based on deviation of the actual rate from a threshold rate. The threshold rate is selected based on the current pressure of the HP line 110. The threshold rate is stored in a data map or table inside the memory element 132 of the control unit 130. The control unit 130 determines the status of the manual SOV 104 to be in closed position, when the actual rate is below the threshold rate. Thus, instead of detecting the condition of reduction of the actual rate as leakage, the control unit 130 is adapted to diagnose the leakage condition as false leakage, thereby eliminates incorrect leakage detection in the HP line 110. With this information, the control unit 130 determines the manual SOV 104 to be in closed position, and consequently provides a signal to alert the driver for opening the manual SOV 104.

[0016] According to another embodiment of the present invention, a control unit 130 to diagnose fault leakage condition in the gaseous fuel supply system 100 of the vehicle is provided. The system 100 comprises the tank 102, storing the gaseous fuel, in connection with the High Pressure (HP) line 110 through the manual SOV 104, the first electronic SOV 106 and the pressure sensor 114. The HP line 110 connected to the Low Pressure (LP) line 120 through the pressure regulator 116, and the LP line 120 connected to the fuel injection unit 134. The control unit 130 adapted to measure the current pressure of the HP line 110 during ignition ON condition of the vehicle. The control unit 130 compares the current pressure with the previous pressure. The previous pressure is accessible from the memory element 132 of the control unit 130. Based on the result of the comparison, the control unit 130 monitors a decrease of the current pressure in the HP line 110 upon start of the engine for a time period. The control unit 130 determines a status of the manual SOV 104 when the current pressure decreases below the expected pressure. The control unit 130 then determines the closed position of the manual SOV 104 as the reason for the actual rate of decrease of the pressure instead of the leakage. The control unit 130 subsequently alerts the driver through suitable notification means to open the manual SOV 104. Alternatively, instead of comparing the current pressure with the expected pressure, the actual rate of decrease of the current pressure, i.e. actual rate, is compared against the threshold rate of decrease.

[0017] An example is now described to provide more clarity on working of the present invention. If the manual SOV 104 is closed and the driver starts the vehicle, the fuel in the tank 102 remains intact, whereas the fuel remaining in the HP line 110 is used up. The pressure sensor 114 gives reading for the pressure in the HP line 110 which is used for all leakage detection in the HP line 110. Now since the manual SOV 104 is closed, the actual rate of pressure reduction in the HP line 110 starts decreases drastically and the control unit 130 wrongly identifies this actual rate as leakage. In the conventional system 100, the control unit 130 triggers all the valves to shut-OFF and eventually the engine shuts down even though there is no leakage. The driver is also unable to start the engine until this error is removed by visiting a service station. However, with the present invention, the control unit 130 is now configured to avoid false leakage condition. The control unit 130 identifies the status of the manual SOV 104 to be in closed position and eliminates the fault detection of the HP line 110.

[0018] The control unit 130 is configured or adapted in the following manner. The pressure of the HP line 110 is monitored all the time even during post drive. So, at the end of every post drive the control unit 130 makes a copy of the pressure in the HP line 110 or the pressure of the tank 102 and stores in the memory element 132 such as Non Volatile Random Access Memory (NVRAM). During next ignition ON, such as T15 ON, the control unit 130 compares the current pressure of the HP line 110 or the tank 102 with the previous pressure stored in the memory element 132. If the current pressure is less than threshold value/limit, then the control unit 130 detects a leakage in the HP line 110 and takes the safety measure such as disables the vehicle start. If the pressure is within the threshold value/limit, then the control unit 130 detects no leak in the HP line 110 and keeps the vehicle in ON condition. The control unit 130 is configured to validate the leakage status of the HP line 110 once the engine is started. If the manual SOV 104 is closed, then the pressure in the HP line 110 starts decreasing drastically as soon as the engine is started. The drastic reduction in the pressure is only because there is a leakage in HP line 110. But since the control unit 130 already checked that there is no leakage in the HP line 110, then the only possible reason for this pressure reduction is the manual SOV 104 is in closed position. The control unit 130 alerts the driver to open the manual SOV 104 and nullifies the detection of leakage.

[0019] Fig. 2 illustrates a method for determining status of a manual SOV in a gaseous fuel supply system, according to an embodiment of the present invention. The system 100 comprises the tank 102, storing the gaseous fuel, the tank 102 in connection with the HP line 110 through the manual SOV 104, the electronic SOV 106 and the pressure sensor 114, the HP line 110 connected to the LP line 120 through the pressure regulator 116, and the LP line 120 connected to the fuel injection unit 134. The method comprising the steps of, a step 202 comprising measuring the current pressure of the HP line 110 during ignition ON condition of the vehicle. For example: as soon as T15 ignition position is ON, the pressure in the HP line 110 is measured and recorded in the memory element 132. A step 204 comprises, comparing the current pressure with a previous pressure. The previous pressure accessible from the memory element 132 of the control unit 130 of the vehicle. The previous pressure is pressure of the HP line 110 measured during at the end of the previous drive cycle of the vehicle. The current pressure is measured before start of the engine of the vehicle. The step 204 directs to step 210, if the current pressure is less than a threshold value/limit. The step 210 comprises detecting the leakage in HP line 110. The control unit 130 stores detection of leakage in the HP line 110 in the memory element 132. However, if the current pressure is within the threshold value/ limit, then the control unit 130 proceeds to next step 206. The step 206 comprises monitoring a decrease of the current pressure in the HP line 110 upon start of the engine for a time period, based on the result of the comparison. A next step 208 comprises determining the status of the manual SOV 104 when the current pressure decreases below the expected pressure in the time period. The status of the manual SOV 104 is determined to be closed, and the leakage in HP line 110 is discarded.

[0020] In an alternative method, the step 206 comprises measuring the actual rate of decrease of the current pressure in the HP line 110 upon start of the engine. The step 208 comprises determining the status of the manual SOV 104, when the actual rate deviates from the threshold rate in the HP line 110. The threshold rate being stored in the memory element 132 of the control unit 130.

[0021] The expected pressure is selected based on the current pressure of the HP line 110. The method further comprises a step 212 comprising determining the manual SOV 104 in the closed position, and consequently providing the signal to alert the driver for opening the manual SOV 104.

[0022] Similarly, a method for diagnosing a false leakage condition in the gaseous fuel supply system 100 is provided. The system 100 comprises the tank 102, storing the gaseous fuel, in connection with the HP line 110 through the manual SOV 104, the electronic SOV 106 and the pressure sensor 114. The HP line 110 connected to the LP line 120 through the pressure regulator 116, and the LP line 120 connected to the fuel injection unit 134. The method comprising the steps of, a step comprising measuring the current pressure of the HP line 110 during ignition ON condition of the vehicle. A next step comprises, comparing the current pressure with the previous pressure. The previous pressure accessible from the memory element 132 of the control unit 130 of the vehicle. A next step comprises monitoring the decrease in the current pressure of the HP line 110 within a time period, based on the result of the comparison. A next step comprises determining the status of the manual SOV 104 when the current pressure is below the expected pressure. Alternatively, actual rate of decrease of the current pressure is compared with a threshold rate for detection of the status of the manual SOV 104.

[0023] The gaseous fuel in the gaseous fuel supply system 100 is any one selected from a group comprising a Compressed Natural Gas (CNG), Liquefied Petroleum Gas (LPG) and the like. An example of the vehicle is a three-wheeler such as an auto rickshaw, a four-wheeler such as a car, and not limited thereto.

[0024] According to an embodiment of the present invention, the vehicle is not stalled as in the conventional system 100, where the driver has to mandatorily take the vehicle to a service station for diagnosis and repair. Instead, now the driver is provided an option to open the manual SOV 104 to continue driving. The present invention provides a method to detect the status of the manual SOV 104 and to avoid the misdetection of the leakage. The present invention identifies the status of the manual SOV 104 and is applicable to any automotive CNG/LPG system 100. The control unit 130 and the method are adaptable for both the direct manufacturer such Original Equipment Manufacturer (OEM) or as a retrofit solution where the manual SOV 104 is used. It is applicable for both mono-fuel and bi-fuel systems. The present invention is realizable at very less cost, leading to reduced overall cost of the vehicle.

[0025] 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