CA2794117C - Method and system for detecting and diagnosing a gaseous fuel leak in a dual fuel internal combustion engine system - Google Patents
Method and system for detecting and diagnosing a gaseous fuel leak in a dual fuel internal combustion engine system Download PDFInfo
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- CA2794117C CA2794117C CA2794117A CA2794117A CA2794117C CA 2794117 C CA2794117 C CA 2794117C CA 2794117 A CA2794117 A CA 2794117A CA 2794117 A CA2794117 A CA 2794117A CA 2794117 C CA2794117 C CA 2794117C
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/08—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed simultaneously using pluralities of fuels
- F02D19/10—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed simultaneously using pluralities of fuels peculiar to compression-ignition engines in which the main fuel is gaseous
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/0623—Failure diagnosis or prevention; Safety measures; Testing
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D41/0027—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures the fuel being gaseous
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/22—Safety or indicating devices for abnormal conditions
- F02D41/221—Safety or indicating devices for abnormal conditions relating to the failure of actuators or electrically driven elements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M43/00—Fuel-injection apparatus operating simultaneously on two or more fuels, or on a liquid fuel and another liquid, e.g. the other liquid being an anti-knock additive
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B2201/00—Fuels
- F02B2201/06—Dual fuel applications
- F02B2201/064—Liquid and gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/22—Safety or indicating devices for abnormal conditions
- F02D2041/224—Diagnosis of the fuel system
- F02D2041/225—Leakage detection
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/06—Fuel or fuel supply system parameters
- F02D2200/0602—Fuel pressure
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/30—Use of alternative fuels, e.g. biofuels
Abstract
A method for detecting and diagnosing a gaseous fuel leak in a dual fuel internal combustion engine system comprises producing a fault signal indicating that there is a leak of gaseous fuel into liquid fuel when an amount of gaseous fuel is detected in the liquid fuel return line through which liquid fuel is returned from the fuel injector to the fuel supply. The method can further comprise diagnosing a failure of the fuel injector or of at least one of the system components which regulate the gaseous fuel and the liquid fuel supply pressures by evaluating if an amount of gaseous fuel has been detected in the liquid fuel return line and calculating the pressure differential between the liquid fuel rail pressure and the gaseous fuel rail pressure.
Description
METHOD AND SYSTEM FOR DETECTING AND DIAGNOSING A GASEOUS
FUEL LEAK IN A DUAL FUEL INTERNAL COMBUSTION ENGINE SYSTEM
Technical Field [0001 ] The present invention relates to a method and a system for detecting and diagnosing a leak of gaseous fuel into liquid fuel in a dual fuel internal combustion engine system. This involves detecting an amount of gaseous fuel in the liquid fuel return line.
Background of the Invention
FUEL LEAK IN A DUAL FUEL INTERNAL COMBUSTION ENGINE SYSTEM
Technical Field [0001 ] The present invention relates to a method and a system for detecting and diagnosing a leak of gaseous fuel into liquid fuel in a dual fuel internal combustion engine system. This involves detecting an amount of gaseous fuel in the liquid fuel return line.
Background of the Invention
[0002] Because of its ready availability, low cost, and potential for reducing particulate emissions, natural gas has proven to be a good substitute for replacing diesel fuel for fuelling internal combustion engines. Since the auto-ignition temperature of natural gas and other gaseous fuels is substantially greater than that of diesel, some gaseous fuelled engines use a small amount of pilot fuel, such as diesel, to ignite the main fuel.
[0003] Some gaseous fuelled engines of this type can use a dual fuel injector injecting both a liquid pilot fuel and a gaseous main fuel. Such engines are "dual fuel" engines which are defined here to mean engines that can be fuelled with two different fuels at the same time. In preferred embodiments, the two fuels are independently and separately injected into the combustion chamber, such that ignition of the gaseous fuel is assisted by the pilot fuel. Such a dual fuel injector is disclosed in the Applicant's co-owned U.S. Patent No. 6,073,862 (the `862 patent) which illustrates a hydraulically actuated dual fuel injector which comprises two concentric needle valves for injecting controlled quantities of a main gaseous fuel and a pilot liquid fuel into the combustion chamber of an internal combustion engine. The injector comprises liquid seals which surround the gaseous fuel needle valve and prevent the leakage of gaseous fuel into the actuating hydraulic fluid around the gaseous fuel needle valve. The hydraulic fluid can be the same as the pilot liquid fuel, for example diesel fuel. The pressure in the gaseous fuel common rail which supplies gaseous fuel to the injector is maintained at a pressure which is slightly less than the pressure in the pilot fuel common rail which supplies pilot liquid fuel to the injector to prevent leakage of gaseous fuel past the liquid seals into the pilot fuel or into the hydraulic fluid.
[0004] From U.S. Patent No. 6,298,833 (the '833 patent), which is also co-owned by the Applicant, it is known to dynamically control sealing-fluid pressure and implicitly pilot fuel pressure to ensure that the gaseous fuel pressure is slightly less than pilot fuel pressure for all engine operating conditions. A pressure-balancing system, comprising for example a dome-loaded regulator helps to maintain a positive pressure differential between the sealing fluid (the pilot fuel) and the gaseous fuel to prevent leakage of the gaseous fuel into the pilot fuel throughout the operating range of engine speeds and loads.
[0005] In systems employing a dome-loaded regulator such as those described in the `833 patent, the pressure differential between the diesel fuel rail pressure and the gaseous fuel rail pressure is generally monitored by measuring the pressures in the diesel fuel common rail and in the gaseous fuel common rail, downstream of the dome-loaded regulator. A negative pressure differential between the diesel fuel supply pressure and the gaseous fuel supply pressure can indicate gaseous fuel leaking into the liquid fuel cavities and passages or into the hydraulic fluid when the liquid fuel is also used as hydraulic fluid. The measured pressures are transmitted to a controller and if, during engine's operation, the calculated pressure differential between the diesel fuel rail pressure and the gaseous fuel rail pressure is negative for a prolonged period of time, the engine is generally switched to operate only on diesel (the run-on-diesel (ROD) mode).
[0006] Intrusion of the gaseous fuel into the liquid fuel can affect the performance of the hydraulic system or can form a combustible mixture in the liquid fuel drain lines.
[0007] Known methods measuring the pressure differential between the diesel fuel supply pressure and the gaseous fuel supply pressure cannot reliably detect the gaseous fuel leakage into liquid fuel. Unit to unit variations and system aging can influence the accuracy of the sensors placed in the pilot fuel and gaseous fuel rails. Furthermore, if there is leakage of gaseous fuel into the liquid fuel, the methods used in the past cannot accurately diagnose if such leakage is caused by a fault in the pressure balancing system or in the dual fuel injector.
[0008] While the problem of monitoring the pressure differential between the gaseous fuel rail pressure and the pilot fuel rail pressure has been addressed in the past, there is still a need for a more accurate method of detecting and diagnosing a gaseous fuel leak in a dual fuel internal combustion engine system.
Summary
Summary
[0009] A method is disclosed for detecting and diagnosing a leak of gaseous fuel into liquid fuel in a dual fuel internal combustion engine system comprising a fuel injector for separately injecting gaseous fuel and liquid fuel into a combustion chamber. The method comprises detecting an amount of gaseous fuel in a liquid fuel return line through which liquid fuel is returned from the fuel injector to a liquid fuel supply, and producing a first fault signal ("Gaseous Fuel Leak to Drain") indicating that gaseous fuel has leaked into the liquid fuel return line when said amount of gaseous fuel is detected in the liquid fuel return line.
[0010] For further diagnosing the gaseous fuel leak to detect if it caused by a fault in the fuel injector or in the pressure regulating components, the method can comprise measuring a liquid fuel rail pressure and a gaseous fuel rail pressure downstream of any system components which regulate the liquid fuel rail pressure and the gaseous fuel rail pressure to respective pressure target values, calculating a pressure differential between the liquid fuel rail pressure and the gaseous fuel rail pressure by subtracting the measured gaseous fuel rail pressure from the measured liquid fuel rail pressure, and comparing the calculated pressure differential to a predetermined range of a nominal pressure differential. The liquid fuel rail pressure is the pressure at which liquid fuel is supplied to the fuel injector and the gaseous fuel rail pressure is the pressure at which gaseous fuel is supplied to the fuel injector.
[0011 ] If the first fault signal is produced and the calculated pressure differential is within or higher than the predetermined range , the method further comprises producing an injector fault signal indicating a failure of the fuel injector.
[0012] If the first fault signal is produced and the calculated pressure differential is lower than the predetermined range, the method further comprises producing a bias fault signal indicating a failure of at least one of the system components which regulate the fuel rail pressures. Because the calculated pressure differential is lower than the predetermined range the bias fault signal is recorded as "Bias out of range low" or "BOL".
[0013] If the first fault signal is not produced and the calculated pressure differential is lower or higher than said predetermined range, the method further comprises producing a bias fault signal indicating a failure of at least one of the system components which regulate the fuel rail pressures. The bias fault signal is recorded as "Bias out of range low" (BOL) or "Bias out of range high" (BOH) when the calculated pressure differential is lower or respectively higher than the predetermined range.
[0014] In preferred embodiments, the presence of gaseous fuel is detected by measuring the pressure in the liquid fuel return line, comparing the value of the measured pressure in the liquid fuel return line to a predetermined nominal pressure, and producing the first fault signal indicating the gaseous fuel leak when the measured pressure in the liquid fuel return line is higher than the predetermined nominal pressure.
[0015] In other embodiments, the presence of gaseous fuel is detected by a gaseous fuel detector placed in the liquid fuel return line between the fuel injector and the liquid fuel supply or in the liquid fuel supply.
[0016] In the present method, the predetermined range of the nominal pressure differential can be constant during engine operation or it can be a function of the engine's speed and/or torque.
[0017] The step of detecting the amount of gaseous fuel in the liquid fuel return line is done by continuous monitoring. In preferred embodiments of the present method, during the engine's transient operation the pressure differential is not calculated to avoid any inaccurate pressure measurements or, in alternate embodiments, the pressure differential is calculated based on the filtered values of the liquid fuel rail pressure and the gaseous fuel rail pressure.
[0018] Preferably, any of said fault signals are generated after a condition that triggers the respective fault signal is recorded for a predetermined period of time.
[0019] A system is disclosed for detecting and diagnosing a leak of gaseous fuel into liquid fuel in a fuel system for a dual fuel internal combustion engine comprising a fuel injector for separately injecting gaseous fuel and liquid fuel into a combustion chamber. The system for detecting and diagnosing said leak comprises a detection system for detecting the presence of gaseous fuel in a liquid return line through which liquid fuel is returned from said fuel injector to a liquid fuel supply and a controller which receives a signal from the detection system and is programmed to generate a first fault signal indicating that gaseous fuel has leaked to the liquid fuel return line based on the received signal.
[0020] In preferred embodiments, the detection system comprises a first pressure sensor for measuring the pressure in the liquid fuel return line which transmits a signal indicative of the measured liquid fuel return line pressure to the controller, and the controller is programmed to compare the received signal to a stored predetermined nominal pressure for the liquid fuel return line and generate the first fault signal indicating that gaseous fuel has leaked to the liquid fuel return line based on the results of this comparison.
[0021 ] Alternatively, the detection system can comprise a pressure switch which makes electrical contact when the pressure in said liquid fuel return line is higher than a stored predetermined nominal pressure for the liquid fuel return line and sends a signal to the controller and the controller is programmed to generate the first fault signal indicating that gaseous fuel has leaked to the liquid fuel return line based on the signal received from the pressure switch.
[0022] In yet another embodiment, the detection system can comprise a gaseous fuel detector placed in the liquid fuel return line or in the liquid fuel supply which supplies liquid fuel to the fuel injector, and the gaseous fuel detector sends a signal to the controller when it detects an amount of gaseous fuel. The controller is programmed to generate the first fault signal indicating that gaseous fuel has leaked to the liquid fuel return line based on said signal received from the gaseous fuel detector.
[0023] The detection system can also comprise a second pressure sensor for measuring a gaseous fuel rail pressure downstream of a system component which regulates the gaseous fuel rail pressure, the second pressure sensor being configured to send a signal indicative of said measured pressure to the controller;
and a third pressure sensor for measuring a liquid fuel rail pressure downstream of a system component which regulates the liquid fuel rail pressure, the third pressure sensor being configured to send a signal indicative of the measured pressure to the controller. The controller is programmed to calculate a pressure differential based on received signals from the second and third pressure sensor by subtracting the measured gaseous fuel rail pressure from the measured liquid fuel rail pressure and comparing the calculated pressure differential to a predetermined range of a nominal pressure differential. The controller generates a bias fault signal indicating a failure of at least one of said system components which regulate the gaseous fuel or liquid fuel rail pressures or an injector fault signal indicating the failure of the fuel injector based on the results of this comparison, thereby diagnosing the causes of the gaseous fuel leak.
[0024] The controller is programmed to generate the bias fault signal ("Bias out of range low" or "BOL") indicating a failure of at least one of said system components which regulate the gaseous fuel or liquid fuel rail pressure when the first fault signal indicating a gaseous fuel leak is produced and the calculated pressure differential is lower than the predetermined range of the nominal pressure differential.
[0025] The controller is programmed to generate an injector fault signal indicating the failure of the fuel injector when the first fault signal indicating a gaseous fuel leak is produced and the calculated pressure differential is within or higher than the predetermined range of the nominal pressure differential.
[0026] The controller is programmed to generate a bias fault signal, "Bias out of range low" (BOL) or "Bias out of range high" (BOH) indicating a failure of at least one of said system components which regulate the gaseous fuel or liquid fuel rail pressure when the first fault signal indicating a gaseous fuel leak is not produced and the calculated pressure differential is lower or, respectively higher the predetermined range of the nominal pressure differential.
[0027] A dual fuel internal combustion engine system is disclosed which comprises an engine fuelled with gaseous fuel and liquid fuel, the system further comprising:
a. a gaseous fuel supply and a liquid fuel supply;
b. a fuel injector for separately injecting gaseous fuel and liquid fuel in a combustion chamber, the fuel injector being fluidly connected to the gaseous fuel supply and the liquid fuel supply through a gaseous fuel supply line and, respectively a liquid fuel supply line, each of said fuel supply lines being provided with a component for regulating the pressure in the respective supply line;
c. a liquid fuel return line fluidly connecting a drain outlet of the fuel injector to the liquid fuel supply line; and d. a detection system for detecting the presence of gaseous fuel in the liquid return line; and e. a controller which receives a signal from the detection system and is capable of generating a first fault signal indicating that there is a gaseous fuel leak to the liquid fuel return line based on said signal.
Brief Description of the Drawings [0028] The drawings illustrate specific preferred embodiments of the invention, but should not be considered as restricting the spirit or scope of the invention in any way.
[0029] Figure 1 is a schematic view of a fuel system for a dual fuel internal combustion engine according to one embodiment of the present invention.
[0030] Figure 2 is a schematic view of a fuel system for a dual fuel internal combustion engine according to a second embodiment of the present invention.
[0031] Figure 3 is a chart illustrating liquid fuel and gaseous fuel rail pressures and bias versus engine torque for the internal combustion engine of Figure 1 operating at one engine speed.
[0032] Figure 4 is a chart illustrating the variation of the liquid fuel and gaseous fuel rail pressures over time, during transient and steady pressure conditions.
[0033] Figure 5 is a chart illustrating the variation of the liquid fuel return line pressure and the variation of the liquid fuel and gaseous fuel rail pressures over time.
[0034] Figure 6 is a diagram illustrating the steps of the present method of detecting and diagnosing a gaseous fuel leak in the fuel injector of a gaseous fuelled engine system.
Detailed Description of the Preferred Embodiments [0035] Referring to FIG. 1, there is shown a schematic view of fuel system 100 for supplying a pilot fuel and a gaseous fuel to a dual fuel internal combustion engine (not illustrated). Fuel system 100 comprises dual fuel injector 102 which allows the separate and independent injection of a gaseous fuel and of a pilot fuel into the combustion chamber of the internal combustion engine. The gaseous fuel is the main fuel for combustion in the engine. In the present disclosure the gaseous fuel is preferably natural gas, but can be other types of gaseous fuels such as methane, propane, butane, hydrogen, and blends of such fuels that can combust when ignited by a pilot fuel. The pilot fuel is a liquid fuel, for example diesel, but can be other types of liquid fuel that are more easily ignitable when injected inside a combustion chamber. The liquid fuel used as pilot fuel for the ignition of the gaseous fuel can also be the hydraulic fluid used for activating the fuel injector and/or the liquid used for the liquid seals which prevent the leakage of gaseous fuel into the hydraulic fluid.
[0036] Fuel system 100 comprises a liquid fuel supply 104 and a gaseous fuel supply 106. Liquid fuel supply 104 can be a liquid fuel tank, which supplies liquid fuel through supply line 108 to liquid fuel pumping apparatus 110. Gaseous fuel supply 106 can be an accumulator which accumulates gaseous fuel from an upstream supply line 112, as illustrated in the present embodiment, or it can be a gas cylinder storing compressed natural gas (CNG). In the present embodiment, the illustrated upstream supply line 112 can be a commercial or residential gas line, or a feed pipe from a supply of liquefied gaseous fuel such as liquefied natural gas (LNG). Gaseous fuel supply 106 supplies gaseous fuel to pressure regulator 114 through line 116. From pressure regulator 114 gaseous fuel is supplied through rail 118 to fuel injector 102.
[0037] Liquid fuel pumping apparatus 110 pressurizes the liquid fuel to a pressure suitable for injection and supplies it through rail 120 to fuel injector 102.
In the present embodiment, pumping apparatus 110 is a liquid fuel pump. Liquid fuel rail 120 is fluidly connected to regulator 114 through line 122. The liquid fuel pressure in rail 120 is substantially equal to the liquid fuel pressure in line 122.
[0038] Although only one fuel injector is shown in FIG. 1, it is understood that in most embodiments this fuel injector is one of a plurality of fuel injectors, each associated with a respective combustion chamber, and in such embodiments liquid fuel rail 120 and gaseous fuel rail 118 are known as the common fuel rails that supply liquid fuel and respectively gaseous fuel to all the fuel injectors.
[0039] Pressure regulator 114 is responsive to liquid fuel pressure in line 122 to regulate gaseous fuel pressure in rail 118 below liquid fuel pressure in line and rail 120. Regulator 114 operates as described in more detail in the afore-mentioned `833 patent. In the present embodiment, regulator 114 is illustrated as a dome-loaded regulator, known to those familiar with this technology.
Pressure regulator 114 maintains a pressure differential between liquid fuel pressure in rail 120 and gaseous fuel in rail 118 to prevent gaseous fuel from leaking past the liquid seals into the liquid fuel as described in the aforementioned `862 and `833 patents. Because of the construction of pressure regulator 114, the pressure differential between liquid fuel rail pressure (LFP) and gaseous fuel rail pressure (GFP) is maintained constant as illustrated in FIG. 3 which represents the liquid fuel and gaseous fuel supply pressures and the pressure differential between them (bias) versus engine torque. In other embodiments, pressure regulator 114 can be replaced by a variable pressure regulator as further described in relation with the embodiment illustrated in FIG. 2.
[0040] Fuel system 100 further comprises a liquid fuel pressure sensor 124 which monitors the pressure in the liquid fuel rail 120 and a gaseous fuel pressure sensor 126 which monitors the pressure in the gaseous fuel rail 118. The pressures measured by sensors 124 and 126 are communicated to electronic controller 130. Electronic controller 130 can be a standalone computer for controlling the fuel system or it can be the engine control unit (ECU) for the engine. Electronic controller 130 commands pumping apparatus 110 responsive to the signals received from pressure sensors 124 and 126. The gaseous fuel pressure (GFP) and the liquid fuel pressure (LFP) are preferably measured when the pressures in respective fuel rails 118 and 120 have stabilized, for example at
[0011 ] If the first fault signal is produced and the calculated pressure differential is within or higher than the predetermined range , the method further comprises producing an injector fault signal indicating a failure of the fuel injector.
[0012] If the first fault signal is produced and the calculated pressure differential is lower than the predetermined range, the method further comprises producing a bias fault signal indicating a failure of at least one of the system components which regulate the fuel rail pressures. Because the calculated pressure differential is lower than the predetermined range the bias fault signal is recorded as "Bias out of range low" or "BOL".
[0013] If the first fault signal is not produced and the calculated pressure differential is lower or higher than said predetermined range, the method further comprises producing a bias fault signal indicating a failure of at least one of the system components which regulate the fuel rail pressures. The bias fault signal is recorded as "Bias out of range low" (BOL) or "Bias out of range high" (BOH) when the calculated pressure differential is lower or respectively higher than the predetermined range.
[0014] In preferred embodiments, the presence of gaseous fuel is detected by measuring the pressure in the liquid fuel return line, comparing the value of the measured pressure in the liquid fuel return line to a predetermined nominal pressure, and producing the first fault signal indicating the gaseous fuel leak when the measured pressure in the liquid fuel return line is higher than the predetermined nominal pressure.
[0015] In other embodiments, the presence of gaseous fuel is detected by a gaseous fuel detector placed in the liquid fuel return line between the fuel injector and the liquid fuel supply or in the liquid fuel supply.
[0016] In the present method, the predetermined range of the nominal pressure differential can be constant during engine operation or it can be a function of the engine's speed and/or torque.
[0017] The step of detecting the amount of gaseous fuel in the liquid fuel return line is done by continuous monitoring. In preferred embodiments of the present method, during the engine's transient operation the pressure differential is not calculated to avoid any inaccurate pressure measurements or, in alternate embodiments, the pressure differential is calculated based on the filtered values of the liquid fuel rail pressure and the gaseous fuel rail pressure.
[0018] Preferably, any of said fault signals are generated after a condition that triggers the respective fault signal is recorded for a predetermined period of time.
[0019] A system is disclosed for detecting and diagnosing a leak of gaseous fuel into liquid fuel in a fuel system for a dual fuel internal combustion engine comprising a fuel injector for separately injecting gaseous fuel and liquid fuel into a combustion chamber. The system for detecting and diagnosing said leak comprises a detection system for detecting the presence of gaseous fuel in a liquid return line through which liquid fuel is returned from said fuel injector to a liquid fuel supply and a controller which receives a signal from the detection system and is programmed to generate a first fault signal indicating that gaseous fuel has leaked to the liquid fuel return line based on the received signal.
[0020] In preferred embodiments, the detection system comprises a first pressure sensor for measuring the pressure in the liquid fuel return line which transmits a signal indicative of the measured liquid fuel return line pressure to the controller, and the controller is programmed to compare the received signal to a stored predetermined nominal pressure for the liquid fuel return line and generate the first fault signal indicating that gaseous fuel has leaked to the liquid fuel return line based on the results of this comparison.
[0021 ] Alternatively, the detection system can comprise a pressure switch which makes electrical contact when the pressure in said liquid fuel return line is higher than a stored predetermined nominal pressure for the liquid fuel return line and sends a signal to the controller and the controller is programmed to generate the first fault signal indicating that gaseous fuel has leaked to the liquid fuel return line based on the signal received from the pressure switch.
[0022] In yet another embodiment, the detection system can comprise a gaseous fuel detector placed in the liquid fuel return line or in the liquid fuel supply which supplies liquid fuel to the fuel injector, and the gaseous fuel detector sends a signal to the controller when it detects an amount of gaseous fuel. The controller is programmed to generate the first fault signal indicating that gaseous fuel has leaked to the liquid fuel return line based on said signal received from the gaseous fuel detector.
[0023] The detection system can also comprise a second pressure sensor for measuring a gaseous fuel rail pressure downstream of a system component which regulates the gaseous fuel rail pressure, the second pressure sensor being configured to send a signal indicative of said measured pressure to the controller;
and a third pressure sensor for measuring a liquid fuel rail pressure downstream of a system component which regulates the liquid fuel rail pressure, the third pressure sensor being configured to send a signal indicative of the measured pressure to the controller. The controller is programmed to calculate a pressure differential based on received signals from the second and third pressure sensor by subtracting the measured gaseous fuel rail pressure from the measured liquid fuel rail pressure and comparing the calculated pressure differential to a predetermined range of a nominal pressure differential. The controller generates a bias fault signal indicating a failure of at least one of said system components which regulate the gaseous fuel or liquid fuel rail pressures or an injector fault signal indicating the failure of the fuel injector based on the results of this comparison, thereby diagnosing the causes of the gaseous fuel leak.
[0024] The controller is programmed to generate the bias fault signal ("Bias out of range low" or "BOL") indicating a failure of at least one of said system components which regulate the gaseous fuel or liquid fuel rail pressure when the first fault signal indicating a gaseous fuel leak is produced and the calculated pressure differential is lower than the predetermined range of the nominal pressure differential.
[0025] The controller is programmed to generate an injector fault signal indicating the failure of the fuel injector when the first fault signal indicating a gaseous fuel leak is produced and the calculated pressure differential is within or higher than the predetermined range of the nominal pressure differential.
[0026] The controller is programmed to generate a bias fault signal, "Bias out of range low" (BOL) or "Bias out of range high" (BOH) indicating a failure of at least one of said system components which regulate the gaseous fuel or liquid fuel rail pressure when the first fault signal indicating a gaseous fuel leak is not produced and the calculated pressure differential is lower or, respectively higher the predetermined range of the nominal pressure differential.
[0027] A dual fuel internal combustion engine system is disclosed which comprises an engine fuelled with gaseous fuel and liquid fuel, the system further comprising:
a. a gaseous fuel supply and a liquid fuel supply;
b. a fuel injector for separately injecting gaseous fuel and liquid fuel in a combustion chamber, the fuel injector being fluidly connected to the gaseous fuel supply and the liquid fuel supply through a gaseous fuel supply line and, respectively a liquid fuel supply line, each of said fuel supply lines being provided with a component for regulating the pressure in the respective supply line;
c. a liquid fuel return line fluidly connecting a drain outlet of the fuel injector to the liquid fuel supply line; and d. a detection system for detecting the presence of gaseous fuel in the liquid return line; and e. a controller which receives a signal from the detection system and is capable of generating a first fault signal indicating that there is a gaseous fuel leak to the liquid fuel return line based on said signal.
Brief Description of the Drawings [0028] The drawings illustrate specific preferred embodiments of the invention, but should not be considered as restricting the spirit or scope of the invention in any way.
[0029] Figure 1 is a schematic view of a fuel system for a dual fuel internal combustion engine according to one embodiment of the present invention.
[0030] Figure 2 is a schematic view of a fuel system for a dual fuel internal combustion engine according to a second embodiment of the present invention.
[0031] Figure 3 is a chart illustrating liquid fuel and gaseous fuel rail pressures and bias versus engine torque for the internal combustion engine of Figure 1 operating at one engine speed.
[0032] Figure 4 is a chart illustrating the variation of the liquid fuel and gaseous fuel rail pressures over time, during transient and steady pressure conditions.
[0033] Figure 5 is a chart illustrating the variation of the liquid fuel return line pressure and the variation of the liquid fuel and gaseous fuel rail pressures over time.
[0034] Figure 6 is a diagram illustrating the steps of the present method of detecting and diagnosing a gaseous fuel leak in the fuel injector of a gaseous fuelled engine system.
Detailed Description of the Preferred Embodiments [0035] Referring to FIG. 1, there is shown a schematic view of fuel system 100 for supplying a pilot fuel and a gaseous fuel to a dual fuel internal combustion engine (not illustrated). Fuel system 100 comprises dual fuel injector 102 which allows the separate and independent injection of a gaseous fuel and of a pilot fuel into the combustion chamber of the internal combustion engine. The gaseous fuel is the main fuel for combustion in the engine. In the present disclosure the gaseous fuel is preferably natural gas, but can be other types of gaseous fuels such as methane, propane, butane, hydrogen, and blends of such fuels that can combust when ignited by a pilot fuel. The pilot fuel is a liquid fuel, for example diesel, but can be other types of liquid fuel that are more easily ignitable when injected inside a combustion chamber. The liquid fuel used as pilot fuel for the ignition of the gaseous fuel can also be the hydraulic fluid used for activating the fuel injector and/or the liquid used for the liquid seals which prevent the leakage of gaseous fuel into the hydraulic fluid.
[0036] Fuel system 100 comprises a liquid fuel supply 104 and a gaseous fuel supply 106. Liquid fuel supply 104 can be a liquid fuel tank, which supplies liquid fuel through supply line 108 to liquid fuel pumping apparatus 110. Gaseous fuel supply 106 can be an accumulator which accumulates gaseous fuel from an upstream supply line 112, as illustrated in the present embodiment, or it can be a gas cylinder storing compressed natural gas (CNG). In the present embodiment, the illustrated upstream supply line 112 can be a commercial or residential gas line, or a feed pipe from a supply of liquefied gaseous fuel such as liquefied natural gas (LNG). Gaseous fuel supply 106 supplies gaseous fuel to pressure regulator 114 through line 116. From pressure regulator 114 gaseous fuel is supplied through rail 118 to fuel injector 102.
[0037] Liquid fuel pumping apparatus 110 pressurizes the liquid fuel to a pressure suitable for injection and supplies it through rail 120 to fuel injector 102.
In the present embodiment, pumping apparatus 110 is a liquid fuel pump. Liquid fuel rail 120 is fluidly connected to regulator 114 through line 122. The liquid fuel pressure in rail 120 is substantially equal to the liquid fuel pressure in line 122.
[0038] Although only one fuel injector is shown in FIG. 1, it is understood that in most embodiments this fuel injector is one of a plurality of fuel injectors, each associated with a respective combustion chamber, and in such embodiments liquid fuel rail 120 and gaseous fuel rail 118 are known as the common fuel rails that supply liquid fuel and respectively gaseous fuel to all the fuel injectors.
[0039] Pressure regulator 114 is responsive to liquid fuel pressure in line 122 to regulate gaseous fuel pressure in rail 118 below liquid fuel pressure in line and rail 120. Regulator 114 operates as described in more detail in the afore-mentioned `833 patent. In the present embodiment, regulator 114 is illustrated as a dome-loaded regulator, known to those familiar with this technology.
Pressure regulator 114 maintains a pressure differential between liquid fuel pressure in rail 120 and gaseous fuel in rail 118 to prevent gaseous fuel from leaking past the liquid seals into the liquid fuel as described in the aforementioned `862 and `833 patents. Because of the construction of pressure regulator 114, the pressure differential between liquid fuel rail pressure (LFP) and gaseous fuel rail pressure (GFP) is maintained constant as illustrated in FIG. 3 which represents the liquid fuel and gaseous fuel supply pressures and the pressure differential between them (bias) versus engine torque. In other embodiments, pressure regulator 114 can be replaced by a variable pressure regulator as further described in relation with the embodiment illustrated in FIG. 2.
[0040] Fuel system 100 further comprises a liquid fuel pressure sensor 124 which monitors the pressure in the liquid fuel rail 120 and a gaseous fuel pressure sensor 126 which monitors the pressure in the gaseous fuel rail 118. The pressures measured by sensors 124 and 126 are communicated to electronic controller 130. Electronic controller 130 can be a standalone computer for controlling the fuel system or it can be the engine control unit (ECU) for the engine. Electronic controller 130 commands pumping apparatus 110 responsive to the signals received from pressure sensors 124 and 126. The gaseous fuel pressure (GFP) and the liquid fuel pressure (LFP) are preferably measured when the pressures in respective fuel rails 118 and 120 have stabilized, for example at
-11-a time T1 as illustrated in FIG. 4. Transient pressure conditions which are present in respective fuel rails 118 and 120 when liquid fuel pressure and/or gaseous fuel pressure are being changed from one pressure to another according to engine demand can generate inaccurate readings of pressure sensors 124 and 126. For example, liquid fuel pressure LFP can change at a different rate than gaseous fuel pressure GFP during transients, which can result in inaccurate pressure differential readings. The controller preferably uses pressure measurements that are taken when the engine speed and torque have stabilized or filters the pressure measurements taken during transients.
[0041 ] Fuel system 100 further comprises a liquid fuel return line 132 through which liquid fuel is returned from fuel injector 102 to liquid fuel supply 104. The pressure in liquid fuel return line 132 is continuously monitored by pressure sensor 134. The measurements of pressure sensor 134 on the liquid fuel return line are communicated to controller 130.
[0042] Another embodiment of the present fuel system is illustrated in FIG. 2.
Fuel system 200 supplies liquid fuel and gaseous fuel to dual fuel injector which is associated to a combustion chamber of an internal combustion engine (not illustrated). Similar to the fuel system illustrated in FIG. 1, dual fuel injector 102 allows the separate and independent injection of a gaseous fuel and of a pilot fuel into the combustion chamber of the internal combustion engine. The pilot fuel is a liquid fuel and the same liquid fuel can also be used as the hydraulic fluid used for activating the fuel injector and/or as the fluid for the liquid seals in the fuel injector. The fuel system illustrated in FIG. 2 is similar to the fuel system illustrated in FIG. 1 and therefore only the differences are discussed here.
[0043] Pressure regulator 214 is a variable pressure regulator that is controlled by controller 230 to regulate the gaseous fuel pressure in gaseous fuel rail 118.
Regulator 214 can be a variable pressure regulator or any other pressure regulating valve that controls the pressure in gaseous fuel rail 118 according to at
[0041 ] Fuel system 100 further comprises a liquid fuel return line 132 through which liquid fuel is returned from fuel injector 102 to liquid fuel supply 104. The pressure in liquid fuel return line 132 is continuously monitored by pressure sensor 134. The measurements of pressure sensor 134 on the liquid fuel return line are communicated to controller 130.
[0042] Another embodiment of the present fuel system is illustrated in FIG. 2.
Fuel system 200 supplies liquid fuel and gaseous fuel to dual fuel injector which is associated to a combustion chamber of an internal combustion engine (not illustrated). Similar to the fuel system illustrated in FIG. 1, dual fuel injector 102 allows the separate and independent injection of a gaseous fuel and of a pilot fuel into the combustion chamber of the internal combustion engine. The pilot fuel is a liquid fuel and the same liquid fuel can also be used as the hydraulic fluid used for activating the fuel injector and/or as the fluid for the liquid seals in the fuel injector. The fuel system illustrated in FIG. 2 is similar to the fuel system illustrated in FIG. 1 and therefore only the differences are discussed here.
[0043] Pressure regulator 214 is a variable pressure regulator that is controlled by controller 230 to regulate the gaseous fuel pressure in gaseous fuel rail 118.
Regulator 214 can be a variable pressure regulator or any other pressure regulating valve that controls the pressure in gaseous fuel rail 118 according to at
-12-least one of the engine's operating parameters, for example engine speed or load. Pressure regulator 214 is not directly responsive to the pressure in liquid fuel rail 120. Controller 230 monitors the pressure signals from pressure sensors 124 and 126 and commands liquid fuel pumping apparatus 110 and pressure regulator 214 to maintain a target pressure differential between liquid fuel pressure in rail 120 and gaseous fuel pressure in rail 118 within a predetermined range of tolerance. The pressure differential between the liquid fuel pressure and the gaseous fuel pressure is selected to prevent gaseous fuel from leaking past the liquid seals into the liquid fuel as described in the aforementioned `862 and `833 patents. In this embodiment, the pressure differential is not constant and can be optimized for each engine operating condition, for example by reducing the pressure differential at idle and lower load conditions and progressively increasing the pressure differential at higher load conditions. The embodiment illustrated in FIG. 2 has the advantage of independently controlling the liquid fuel pressure and the gaseous fuel pressure such that an optimum pressure differential is maintained during transients when the liquid fuel pressure (LFP) and the gaseous fuel pressure (GFP) fluctuate as illustrated in FIG. 4.
[0044] In Fig. 2 electronic controller 230 can be a standalone computer for controlling the fuel system or it can be the engine control unit (ECU) for the engine.
[0045] In both embodiments illustrated in Figures 1 and 2 liquid fuel rail pressure and gaseous fuel rail pressure are measured by pressure sensor 124 and, respectively 126, and the pressure in liquid fuel return line 132 is continuously monitored by pressure sensor 134. Signals from pressure sensors 124, 126 and 134 are communicated to controller 130 and respectively 230 which record the pressure variation in the respective fuel lines. An example of such a map that can be recorded by controller 130 or 230 is illustrated in FIG. 5.
[0046] The pressure differential between liquid fuel pressure (LFP) in rail 120 and gaseous fuel pressure (GFP) in rail 118 is preferably maintained positive,
[0044] In Fig. 2 electronic controller 230 can be a standalone computer for controlling the fuel system or it can be the engine control unit (ECU) for the engine.
[0045] In both embodiments illustrated in Figures 1 and 2 liquid fuel rail pressure and gaseous fuel rail pressure are measured by pressure sensor 124 and, respectively 126, and the pressure in liquid fuel return line 132 is continuously monitored by pressure sensor 134. Signals from pressure sensors 124, 126 and 134 are communicated to controller 130 and respectively 230 which record the pressure variation in the respective fuel lines. An example of such a map that can be recorded by controller 130 or 230 is illustrated in FIG. 5.
[0046] The pressure differential between liquid fuel pressure (LFP) in rail 120 and gaseous fuel pressure (GFP) in rail 118 is preferably maintained positive,
-13-meaning that the liquid fuel pressure is preferably higher than the gaseous fuel pressure to prevent any gaseous fuel leakage in the fuel injector. If at a time T2, during the engine operation, gaseous fuel pressure GFP becomes higher than liquid fuel pressure LFP and such negative pressure differential is maintained over a period of time, gaseous fuel may leak into liquid fuel within fuel injector 102 and further into liquid fuel return line. Pressure sensor 134 will therefore record at a time T3, after time T2, an increase in liquid fuel return pressure (LFRP) thereby indicating that there is gaseous fuel leak into the liquid fuel return line 132. If gaseous fuel pressure GFP drops at a time T4 and becomes lower than liquid fuel pressure LFP, the condition of positive pressure differential is re-established and pressure sensor 134 will indicate at a delayed time T5 a drop in liquid fuel return pressure LFRP. Pressure sensor 134 can be located in liquid fuel return line 132 anywhere between dual fuel injector 102 and liquid fuel supply 104. The time delay in recording a pressure increase or a pressure drop in liquid fuel return line 132 will be shorter if pressure sensor 134 is located closer to fuel injector 102.
[0047] In an alternative embodiment, the detection system for detecting a leak of gaseous fuel into the liquid fuel return line comprises a pressure switch instead of pressure sensor 134 and the pressure switch establishes electrical contact when the pressure in liquid fuel return line 132 exceeds a predetermined nominal value and communicates this information to the controller without recording a pressure trace as illustrated in FIG. 5.
[0048] Furthermore, in other embodiments, the detection system for detecting a leak of gaseous fuel into the liquid fuel return line can comprise a gaseous fuel detector instead of pressure sensor 134 and the gaseous fuel detector can be placed in the liquid fuel return line 132 between fuel injector 102 and liquid fuel supply 104 or directly within liquid fuel supply 104. Controller 130 or 230 receives a signal from the gaseous fuel detector indicating if an amount of gaseous fuel has been detected in the liquid fuel return line 132 and generates a fault signal indicating a gaseous fuel leak into the liquid fuel return line.
[0047] In an alternative embodiment, the detection system for detecting a leak of gaseous fuel into the liquid fuel return line comprises a pressure switch instead of pressure sensor 134 and the pressure switch establishes electrical contact when the pressure in liquid fuel return line 132 exceeds a predetermined nominal value and communicates this information to the controller without recording a pressure trace as illustrated in FIG. 5.
[0048] Furthermore, in other embodiments, the detection system for detecting a leak of gaseous fuel into the liquid fuel return line can comprise a gaseous fuel detector instead of pressure sensor 134 and the gaseous fuel detector can be placed in the liquid fuel return line 132 between fuel injector 102 and liquid fuel supply 104 or directly within liquid fuel supply 104. Controller 130 or 230 receives a signal from the gaseous fuel detector indicating if an amount of gaseous fuel has been detected in the liquid fuel return line 132 and generates a fault signal indicating a gaseous fuel leak into the liquid fuel return line.
-14-[0049] The diagram of FIG. 6 illustrates the steps of the present method which is performed within controller 130 illustrated in FIG. 1 for detecting and diagnosing a gaseous fuel leak in a dual fuel internal combustion engine system. The same method can be applied to the fuel system illustrated in FIG. 2 and the steps of the method will then be executed in the memory of controller 230.
[0050] Pressure sensor 134 measures the pressure (LFRPm) in liquid fuel return line 132 and sends a signal indicative of the LFRPm pressure to controller 130.
Controller 130 compares measured liquid fuel return pressure LFRPm to a predetermined nominal pressure LFRPc stored in the controller's memory and it produces a fault signal indicating that there is a gaseous fuel leak into the liquid fuel return line ("Gaseous Fuel Leak to Drain") if measured liquid fuel return pressure LFRPm is higher than predetermined liquid fuel return pressure LFRPC.
This means there is a gaseous fuel leak in the fuel injector and that gaseous fuel has leaked into the liquid fuel return line. Controller 130 can be programmed such that the measured liquid fuel return pressure has to be higher than the predetermined liquid fuel return pressure by a predetermined threshold before it generates the fault signal indicating a gaseous fuel leak to the liquid fuel return line. In engine systems designed to be less tolerant to gaseous fuel - liquid fuel mixtures controller 130 or 230 can be programmed to generate a fault signal immediately after pressure sensor 134 detects a pressure increase in the liquid fuel return line over a predetermined value.
[0051] In alternative embodiments, if a pressure switch is used instead of a pressure sensor and if the measured pressure in the liquid fuel return line LFRPm is higher than the predetermined nominal pressure LFRPc the switch sends an electrical signal to the controller which outputs a fault signal indicating that there is a gaseous fuel leak to drain. Similarly, if a gaseous fuel detector is used instead of the pressure sensor in the liquid fuel return line, the controller receives a signal from the gaseous fuel detector that an amount of gaseous fuel is detected in the liquid fuel return line and outputs a fault signal indicating the gaseous fuel leak to drain.
[0050] Pressure sensor 134 measures the pressure (LFRPm) in liquid fuel return line 132 and sends a signal indicative of the LFRPm pressure to controller 130.
Controller 130 compares measured liquid fuel return pressure LFRPm to a predetermined nominal pressure LFRPc stored in the controller's memory and it produces a fault signal indicating that there is a gaseous fuel leak into the liquid fuel return line ("Gaseous Fuel Leak to Drain") if measured liquid fuel return pressure LFRPm is higher than predetermined liquid fuel return pressure LFRPC.
This means there is a gaseous fuel leak in the fuel injector and that gaseous fuel has leaked into the liquid fuel return line. Controller 130 can be programmed such that the measured liquid fuel return pressure has to be higher than the predetermined liquid fuel return pressure by a predetermined threshold before it generates the fault signal indicating a gaseous fuel leak to the liquid fuel return line. In engine systems designed to be less tolerant to gaseous fuel - liquid fuel mixtures controller 130 or 230 can be programmed to generate a fault signal immediately after pressure sensor 134 detects a pressure increase in the liquid fuel return line over a predetermined value.
[0051] In alternative embodiments, if a pressure switch is used instead of a pressure sensor and if the measured pressure in the liquid fuel return line LFRPm is higher than the predetermined nominal pressure LFRPc the switch sends an electrical signal to the controller which outputs a fault signal indicating that there is a gaseous fuel leak to drain. Similarly, if a gaseous fuel detector is used instead of the pressure sensor in the liquid fuel return line, the controller receives a signal from the gaseous fuel detector that an amount of gaseous fuel is detected in the liquid fuel return line and outputs a fault signal indicating the gaseous fuel leak to drain.
-15-[0052] In parallel to the measurements of pressure sensor 134, pressure sensors 124 and 126 measure the pressure (LFP) in liquid fuel rail 120 and respectively the pressure (GFP) in gaseous fuel rail 118 and send signals indicative of the measured pressures to controller 130 which calculates the pressure differential between the measured liquid fuel rail pressure and gaseous fuel rail pressure and records it as bias B. The pressure in fuel rails 118 and 120 are measured downstream of any system components that regulate the pressure in the rails to their respective target values. The calculated pressure differential (bias B) is compared to a predetermined range of the nominal pressure differential which comprises values between a predetermined minimum (Bmin) and a predetermined maximum (Bmax).
[0053] The controller can then further correlate between the comparisons of the liquid fuel return pressure and of the calculated pressure differential to their respective predetermined nominal values or range of values and can produce additional fault signals diagnosing an existing gaseous fuel leak to drain as explained below.
[0054] If measured liquid fuel return pressure LFRPm is higher than predetermined nominal pressure LFRPc (LFRPm > LFRPc) and calculated pressure differential B is within the predetermined range of the nominal pressure differential (Bmin < B < Bmax) or is higher than a maximum value of the predetermined range of a nominal pressure differential (B > Bmax) the controller produces an additional fault signal indicating a failure of the fuel injector.
This means that the system components regulating the pressure in the fuel rails (e.g.
pressure regulator 114 or 214 and pumping apparatus 110) work within the prescribed parameters, but that fuel injector 102 is defective which causes a gaseous fuel leak to the liquid fuel.
[0055] If measured liquid fuel return pressure LFRPm is higher than a calibrated nominal pressure LFRPc (LFRPm > LFRPc) and calculated pressure differential B
is lower than the minimum value of the predetermined range of a nominal
[0053] The controller can then further correlate between the comparisons of the liquid fuel return pressure and of the calculated pressure differential to their respective predetermined nominal values or range of values and can produce additional fault signals diagnosing an existing gaseous fuel leak to drain as explained below.
[0054] If measured liquid fuel return pressure LFRPm is higher than predetermined nominal pressure LFRPc (LFRPm > LFRPc) and calculated pressure differential B is within the predetermined range of the nominal pressure differential (Bmin < B < Bmax) or is higher than a maximum value of the predetermined range of a nominal pressure differential (B > Bmax) the controller produces an additional fault signal indicating a failure of the fuel injector.
This means that the system components regulating the pressure in the fuel rails (e.g.
pressure regulator 114 or 214 and pumping apparatus 110) work within the prescribed parameters, but that fuel injector 102 is defective which causes a gaseous fuel leak to the liquid fuel.
[0055] If measured liquid fuel return pressure LFRPm is higher than a calibrated nominal pressure LFRPc (LFRPm > LFRPc) and calculated pressure differential B
is lower than the minimum value of the predetermined range of a nominal
-16-pressure differential Bmin (B < Bmin) the controller produces an additional signal indicating that at least one of the system components which regulate the fuel pressure in the fuel rails, for example pumping apparatus 110 or regulator 114 or 214) has failed. This means that a smaller pressure differential than predetermined has caused gaseous fuel to leak to liquid fuel drain and the fault is recorded as "Bias out of range low" (BOL).
[0056] If the measured liquid fuel return pressure LFRPm is within the predetermined limits, more specifically if it is equal to or smaller than the predetermined nominal pressure LFRP, , (LFRPm = or < LFRP,.) and if the calculated pressure differential B is outside of the predetermined range for the pressure differential, more specifically if it is higher or lower than a maximum value or respectively a minimum value of this predetermined range (B < Bmin or B
> Bmax) the controller produces an additional fault signal indicating a failure of at least one of the system components which regulate the pressure in fuel rails and 120. The fault signal is recorded as "Bias out of range high" (BOH) if the pressure differential is higher than apredetermined maximum value and the fault signal is recorded as "Bias out of range low" (BOL) if the pressure differential is lower than a predetermined minimum value. This means that gaseous fuel is not leaking into the liquid fuel return line, but because the calculated pressure differential between the pressure in liquid fuel rail 120 and the pressure in gaseous fuel rail 118 is out of range at least one the system components regulating the pressure in the fuel rails is not working properly.
[0057] In alternative embodiments, the above steps can also be implemented when detecting a gaseous fuel leak using a pressure switch or a gaseous fuel detector instead of comparing the measured liquid fuel return pressure to a predetermined nominal pressure.
[0058] In the present method if the calculated pressure differential B is outside of the predetermined range for the pressure differential, more specifically if it is higher or lower than a maximum value or respectively a minimum value of this
[0056] If the measured liquid fuel return pressure LFRPm is within the predetermined limits, more specifically if it is equal to or smaller than the predetermined nominal pressure LFRP, , (LFRPm = or < LFRP,.) and if the calculated pressure differential B is outside of the predetermined range for the pressure differential, more specifically if it is higher or lower than a maximum value or respectively a minimum value of this predetermined range (B < Bmin or B
> Bmax) the controller produces an additional fault signal indicating a failure of at least one of the system components which regulate the pressure in fuel rails and 120. The fault signal is recorded as "Bias out of range high" (BOH) if the pressure differential is higher than apredetermined maximum value and the fault signal is recorded as "Bias out of range low" (BOL) if the pressure differential is lower than a predetermined minimum value. This means that gaseous fuel is not leaking into the liquid fuel return line, but because the calculated pressure differential between the pressure in liquid fuel rail 120 and the pressure in gaseous fuel rail 118 is out of range at least one the system components regulating the pressure in the fuel rails is not working properly.
[0057] In alternative embodiments, the above steps can also be implemented when detecting a gaseous fuel leak using a pressure switch or a gaseous fuel detector instead of comparing the measured liquid fuel return pressure to a predetermined nominal pressure.
[0058] In the present method if the calculated pressure differential B is outside of the predetermined range for the pressure differential, more specifically if it is higher or lower than a maximum value or respectively a minimum value of this
-17-predetermined range (B < Bmin or B > Bmax) the controller produces an additional fault signal indicating a failure of at least one of the system components which regulate the pressure in fuel rails or, depending on the measured pressure in the fuel return line, a failure of the fuel injector The controller can be programmed to generate this additional fault signal right away after the calculated pressure differential B is greater than Bmax or smaller than Bmin, or it can generate this additional fault signal at a predetermined time after this condition is detected.
Alternatively, the calculated pressure differential B has to be greater than Bmax or smaller than Bmin by a predetermined threshold before the controller generates a fault signal. The predetermined threshold for generating a fault signal indicating a failure of the injector can be different than the threshold for generating a fault signal indicating a failure of at least one of the system components which regulate the pressure in fuel rails.
[0059] The described method relies on the measurements received from pressure sensors 124, 126 and 134. If the system detects an alarm indicating that any of these sensors stopped working properly the controller aborts the entire method.
[0060] At a predetermined time after controller 130 generates a fault signal indicating that there is a gaseous fuel leak in the liquid fuel return line the engine is switched to the run-on-diesel operation mode whereby the engine is fuelled only with liquid fuel. The predetermined time after which the engine is switched to the run-on-diesel mode depends on the engine system design, especially its other existing safety features addressing the hazard posed by a gaseous fuel/liquid fuel mixture present in the fuel injector, in the liquid fuel return line or in the liquid fuel supply.
[0061 ] The controller in the fuel system described here can be programmed such that it generates a fault signal after a predetermined period of time after the condition which triggers such a fault signal is detected. For example, controller 130 or 230 will generate a fault signal indicating that there is a gaseous fuel leak
Alternatively, the calculated pressure differential B has to be greater than Bmax or smaller than Bmin by a predetermined threshold before the controller generates a fault signal. The predetermined threshold for generating a fault signal indicating a failure of the injector can be different than the threshold for generating a fault signal indicating a failure of at least one of the system components which regulate the pressure in fuel rails.
[0059] The described method relies on the measurements received from pressure sensors 124, 126 and 134. If the system detects an alarm indicating that any of these sensors stopped working properly the controller aborts the entire method.
[0060] At a predetermined time after controller 130 generates a fault signal indicating that there is a gaseous fuel leak in the liquid fuel return line the engine is switched to the run-on-diesel operation mode whereby the engine is fuelled only with liquid fuel. The predetermined time after which the engine is switched to the run-on-diesel mode depends on the engine system design, especially its other existing safety features addressing the hazard posed by a gaseous fuel/liquid fuel mixture present in the fuel injector, in the liquid fuel return line or in the liquid fuel supply.
[0061 ] The controller in the fuel system described here can be programmed such that it generates a fault signal after a predetermined period of time after the condition which triggers such a fault signal is detected. For example, controller 130 or 230 will generate a fault signal indicating that there is a gaseous fuel leak
-18-to the liquid fuel return line at a predetermined period of time after detecting that the pressure signal sent by pressure sensor 134 is higher than a predetermined liquid fuel return line pressure. The delay time for generating a gaseous fuel leak fault signal depends on the engine system's tolerance to gaseous fuel/liquid fuel mixtures. Similarly controller 130 or 230 will generate an additional fault signal indicating a failure of at least one of the system components which regulate the pressure in fuel rails (e.g. BOL, BOH) at a predetermined period of time after the condition which triggers this fault signal is detected.
[0062] The predetermined nominal pressure in the liquid fuel return line and the predetermined range of the nominal pressure differential between liquid fuel rail pressure and gaseous fuel rail pressure are stored in the memory of the controller. The predetermined nominal pressure in the liquid fuel return line is generally a constant value for a particular engine system, determined by testing.
The predetermined range of the nominal pressure differential (bias B) can be constant, for example for an engine fuel system illustrated in FIG. 1 or it can be variable, for example for an engine fuel system illustrated in FIG. 2. When bias B
is variable, the memory of controller 130 can comprise a two-dimensional look-up table which correlates the values of bias B with the engine speed and torque, for example.
[0063] The preferred method has the advantage that it can detect a gaseous fuel leak to the liquid fuel return line and at the same time it can identify the cause of the failure mode as either a defective pressure regulating system component or a defective fuel injector.
[0064] While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood, that the invention is not limited thereto since modifications can be made by those skilled in the art without departing from the scope of the present disclosure, particularly in light of the foregoing teachings.
[0062] The predetermined nominal pressure in the liquid fuel return line and the predetermined range of the nominal pressure differential between liquid fuel rail pressure and gaseous fuel rail pressure are stored in the memory of the controller. The predetermined nominal pressure in the liquid fuel return line is generally a constant value for a particular engine system, determined by testing.
The predetermined range of the nominal pressure differential (bias B) can be constant, for example for an engine fuel system illustrated in FIG. 1 or it can be variable, for example for an engine fuel system illustrated in FIG. 2. When bias B
is variable, the memory of controller 130 can comprise a two-dimensional look-up table which correlates the values of bias B with the engine speed and torque, for example.
[0063] The preferred method has the advantage that it can detect a gaseous fuel leak to the liquid fuel return line and at the same time it can identify the cause of the failure mode as either a defective pressure regulating system component or a defective fuel injector.
[0064] While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood, that the invention is not limited thereto since modifications can be made by those skilled in the art without departing from the scope of the present disclosure, particularly in light of the foregoing teachings.
Claims (21)
1. A method of detecting and diagnosing a leak of gaseous fuel into liquid fuel in a dual fuel internal combustion engine system comprising a fuel injector for separately injecting gaseous fuel and liquid fuel into a combustion chamber, said method comprising a. detecting an amount of gaseous fuel in a liquid fuel return line through which liquid fuel is returned from said fuel injector to a liquid fuel supply; and b. producing a first fault signal indicating that gaseous fuel has leaked into said liquid fuel return line when said amount of gaseous fuel is detected in said liquid fuel return line.
2. The method of claim 1 further comprising:
a. measuring a liquid fuel rail pressure and a gaseous fuel rail pressure downstream of any system components which regulate said liquid fuel rail pressure and said gaseous fuel rail pressure to respective pressure target values;
b. calculating a pressure differential between said liquid fuel rail pressure and said gaseous fuel rail pressure by subtracting said measured gaseous fuel rail pressure from said measured liquid fuel rail pressure; and c. comparing said calculated pressure differential to a predetermined range of a nominal pressure differential.
a. measuring a liquid fuel rail pressure and a gaseous fuel rail pressure downstream of any system components which regulate said liquid fuel rail pressure and said gaseous fuel rail pressure to respective pressure target values;
b. calculating a pressure differential between said liquid fuel rail pressure and said gaseous fuel rail pressure by subtracting said measured gaseous fuel rail pressure from said measured liquid fuel rail pressure; and c. comparing said calculated pressure differential to a predetermined range of a nominal pressure differential.
3. The method of claim 2 wherein if said first fault signal is produced and said calculated pressure differential is within or higher than said predetermined range, producing an injector fault signal indicating a failure of said fuel injector.
4. The method of claim 2 wherein if said first fault signal is produced and said calculated pressure differential is lower than said predetermined range, producing a bias fault signal indicating a failure of at least one of said system components which regulate said fuel rail pressures.
5. The method of claim 2 wherein if said first fault signal is not produced and said calculated pressure differential is lower or higher than said predetermined range, producing a bias fault signal indicating a failure of at least one of said system components which regulate said fuel rail pressures.
6. The method of claim 1 wherein said amount of gaseous fuel is detected by:
a. measuring the pressure in said liquid fuel return line;
b. comparing said value of said measured pressure in said liquid fuel return line to a predetermined nominal pressure; and c. producing said first fault signal indicating said gaseous fuel leak when said measured pressure in said liquid fuel return line is higher than said predetermined nominal pressure.
a. measuring the pressure in said liquid fuel return line;
b. comparing said value of said measured pressure in said liquid fuel return line to a predetermined nominal pressure; and c. producing said first fault signal indicating said gaseous fuel leak when said measured pressure in said liquid fuel return line is higher than said predetermined nominal pressure.
7. The method of claim 1 wherein said presence of gaseous fuel is detected by a gaseous fuel detector placed in said liquid fuel return line between said fuel injector and said liquid fuel supply or in said liquid fuel supply.
8. The method of claim 2 wherein said predetermined range of said nominal pressure differential is constant during said engine operation.
9. The method of claim 2 wherein said predetermined range of said nominal pressure differential is a function of said engine's speed, said engine torque and/or another engine parameter.
10. The method of claim 1 wherein said step of detecting said amount of gaseous fuel in said liquid fuel return line is done by continuous monitoring.
11. The method of any one of claims 2 to 5 wherein during said engine's transient operation said pressure differential is not calculated or is calculated based on filtered values of said liquid fuel rail pressure and said gaseous fuel rail pressure..
12. The method of any one of claims 1 to 11 wherein any of said fault signals are generated after a condition that triggers said respective fault signal is recorded for a predetermined period of time.
13.A system for detecting and diagnosing a leak of gaseous fuel into liquid fuel in a fuel system for a dual fuel internal combustion engine comprising a fuel injector for separately injecting gaseous fuel and liquid fuel into a combustion chamber, said system for detecting and diagnosing said gaseous fuel leak comprising;
a. a detection system for detecting the presence of gaseous fuel in a liquid return line through which liquid fuel is returned from said fuel injector to a liquid fuel supply; and b. a controller which receives a signal from said detection system and is programmed to generate a first fault signal indicating that said gaseous fuel has leaked to said liquid fuel return line based on said signal.
a. a detection system for detecting the presence of gaseous fuel in a liquid return line through which liquid fuel is returned from said fuel injector to a liquid fuel supply; and b. a controller which receives a signal from said detection system and is programmed to generate a first fault signal indicating that said gaseous fuel has leaked to said liquid fuel return line based on said signal.
14. The system of claim 13 wherein said detection system further comprises a first pressure sensor for measuring the pressure in said liquid fuel return line which transmits a signal indicative of said measured liquid fuel return line pressure to said controller, and wherein said controller is programmed to compare said received signal to a stored predetermined nominal pressure for said liquid fuel return line and generate said first fault signal based on said comparison.
15. The system of claim 13 wherein said detection system further comprises a pressure switch which makes electrical contact when said pressure in said liquid fuel return line is higher than a stored predetermined nominal pressure for said liquid fuel return line and sends a signal to said controller and wherein said controller is programmed to generate said first fault signal based on said signal received from said pressure switch.
16. The system of claim 13 wherein said detection system further comprises a gaseous fuel detector placed in said liquid fuel return line or in a liquid fuel supply which supplies liquid fuel to said fuel injector which sends a signal to said controller when it detects an amount of gaseous fuel and wherein said controller is programmed to generate said first fault signal based on said signal received from said gaseous fuel detector.
17. The system of any one of claims 13 to 16 further comprising:
a. a second pressure sensor for measuring a gaseous fuel rail pressure downstream of a system component which regulates said gaseous fuel rail pressure, said second pressure sensor being configured to send a signal indicative of said measured pressure to said controller;
and b. a third pressure sensor for measuring a liquid fuel rail pressure downstream of a system component which regulates said liquid fuel rail pressure, said third pressure sensor being configured to send a signal indicative of said measured pressure to said controller, wherein said controller is programmed to calculate a pressure differential based on received signals from said second and third pressure sensor by subtracting said measured gaseous fuel rail pressure from said measured liquid fuel rail pressure and comparing said calculated pressure differential to a predetermined range of a nominal pressure differential and wherein said controller is programmed to generate a bias fault signal indicating a failure of at least one of said system components which regulate the gaseous fuel or liquid fuel rail pressures or an injector fault signal indicating failure of said fuel injector based on said comparison.
a. a second pressure sensor for measuring a gaseous fuel rail pressure downstream of a system component which regulates said gaseous fuel rail pressure, said second pressure sensor being configured to send a signal indicative of said measured pressure to said controller;
and b. a third pressure sensor for measuring a liquid fuel rail pressure downstream of a system component which regulates said liquid fuel rail pressure, said third pressure sensor being configured to send a signal indicative of said measured pressure to said controller, wherein said controller is programmed to calculate a pressure differential based on received signals from said second and third pressure sensor by subtracting said measured gaseous fuel rail pressure from said measured liquid fuel rail pressure and comparing said calculated pressure differential to a predetermined range of a nominal pressure differential and wherein said controller is programmed to generate a bias fault signal indicating a failure of at least one of said system components which regulate the gaseous fuel or liquid fuel rail pressures or an injector fault signal indicating failure of said fuel injector based on said comparison.
18. The system of claim 17 wherein said controller is programmed to generate said bias fault signal indicating said failure of at least one of said system components which regulate the gaseous fuel or liquid fuel rail pressure when said first fault signal is produced and said calculated pressure differential is lower than said predetermined range of said nominal pressure differential.
19. The system of claim 17 wherein said controller is programmed to generate said injector fault signal indicating said failure of said fuel injector when said first fault signal is produced and said calculated pressure differential is within or higher than said predetermined range of said nominal pressure differential.
20. The system of claim 17 wherein said controller is programmed to generate said bias fault signal indicating a failure of at least one of said system components which regulate the gaseous fuel or liquid fuel rail pressure when said first fault signal is not produced and said calculated pressure differential is lower or higher said predetermined range of said nominal pressure differential.
21.A fuel system for dual fuel internal combustion engine fuelled with gaseous fuel and liquid fuel, said fuel system comprising:
a. a gaseous fuel supply and a liquid fuel supply;
b. a fuel injector for separately injecting said gaseous fuel and said liquid fuel in a combustion chamber, said fuel injector being fluidly connected to said gaseous fuel supply and said liquid fuel supply through a gaseous fuel supply line and, respectively a liquid fuel supply line, each of said fuel supply lines being provided with a component for regulating the pressure in said respective supply line;
c. a liquid fuel return line fluidly connecting a drain outlet of said fuel injector to said liquid fuel supply line; and d. a detection system for detecting the presence of gaseous fuel in said liquid return line; and e. a controller which receives a signal from said detection system and is capable of generating a first fault signal indicating that there is a gaseous fuel leak to said liquid fuel return line based on said signal.
a. a gaseous fuel supply and a liquid fuel supply;
b. a fuel injector for separately injecting said gaseous fuel and said liquid fuel in a combustion chamber, said fuel injector being fluidly connected to said gaseous fuel supply and said liquid fuel supply through a gaseous fuel supply line and, respectively a liquid fuel supply line, each of said fuel supply lines being provided with a component for regulating the pressure in said respective supply line;
c. a liquid fuel return line fluidly connecting a drain outlet of said fuel injector to said liquid fuel supply line; and d. a detection system for detecting the presence of gaseous fuel in said liquid return line; and e. a controller which receives a signal from said detection system and is capable of generating a first fault signal indicating that there is a gaseous fuel leak to said liquid fuel return line based on said signal.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2794117A CA2794117C (en) | 2012-10-31 | 2012-10-31 | Method and system for detecting and diagnosing a gaseous fuel leak in a dual fuel internal combustion engine system |
| PCT/CA2013/050756 WO2014066995A1 (en) | 2012-10-31 | 2013-10-08 | Method and system for detecting and diagnosing a gaseous fuel leak in a dual fuel internal combustion engine system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2794117A CA2794117C (en) | 2012-10-31 | 2012-10-31 | Method and system for detecting and diagnosing a gaseous fuel leak in a dual fuel internal combustion engine system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2794117A1 CA2794117A1 (en) | 2013-01-10 |
| CA2794117C true CA2794117C (en) | 2013-11-12 |
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| Application Number | Title | Priority Date | Filing Date |
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| CA2794117A Active CA2794117C (en) | 2012-10-31 | 2012-10-31 | Method and system for detecting and diagnosing a gaseous fuel leak in a dual fuel internal combustion engine system |
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| Country | Link |
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| CA (1) | CA2794117C (en) |
| WO (1) | WO2014066995A1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2809539C (en) | 2013-03-15 | 2014-05-13 | Westport Power Inc. | Preventing fuel regulation failure |
| US10519877B2 (en) | 2016-11-18 | 2019-12-31 | Caterpillar Inc. | Mitigation of intermittent cylinder misfire on dual fuel engines |
| IT201800009743A1 (en) * | 2018-10-24 | 2020-04-24 | Landi Renzo Spa | DEVICE FOR REGULATING THE PRESSURE OF A GASEOUS FUEL AND DUAL FUEL SUPPLY SYSTEM WITH DIRECT INJECTION |
| DE102019203424A1 (en) * | 2019-03-13 | 2020-09-17 | Robert Bosch Gmbh | Method for operating a fuel system, control unit and fuel system |
| CN111765020B (en) * | 2020-07-08 | 2021-11-19 | 潍柴动力股份有限公司 | Gas rail pressure adjusting method and system |
| CN114992020B (en) * | 2022-05-10 | 2024-03-19 | 潍柴动力股份有限公司 | Method and device for determining fuel rail pressure of HPDI engine and controller of vehicle |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| DE19521791A1 (en) * | 1995-06-15 | 1996-12-19 | Daimler Benz Ag | Method for detecting malfunctions in a fuel injection system of an internal combustion engine |
| US7392792B2 (en) * | 2006-08-21 | 2008-07-01 | Caterpillar Inc. | System for dynamically detecting fuel leakage |
| US20090139488A1 (en) * | 2007-11-30 | 2009-06-04 | Caterpillar Inc. | Diagnostic system for high pressure fuel system |
| US8635985B2 (en) * | 2008-01-07 | 2014-01-28 | Mcalister Technologies, Llc | Integrated fuel injectors and igniters and associated methods of use and manufacture |
| US9140161B2 (en) * | 2010-06-07 | 2015-09-22 | Alset Ip S A R.L. | Bi-fuel engine with variable air fuel ratio |
| JP5394330B2 (en) * | 2010-06-17 | 2014-01-22 | 愛三工業株式会社 | Evaporative fuel treatment device leak diagnosis device |
-
2012
- 2012-10-31 CA CA2794117A patent/CA2794117C/en active Active
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| Publication number | Publication date |
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| WO2014066995A1 (en) | 2014-05-08 |
| CA2794117A1 (en) | 2013-01-10 |
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