System and method for resetting pressure relief valve of common rail fuel system

Abstract

According to one aspect of the present disclosure, a method of controlling a common rail fuel system of an engine system is provided. The common rail fuel system includes a fuel pump, a fuel rail, a plurality of fuel injectors, and a pressure responsive relief valve fluidly coupled with the fuel rail. The method includes identifying a pressure condition of the fuel rail indicating that the pressure responsive relief valve is in open and closed conditions based on detecting an increase and decrease in rail pressure for a threshold period of time. The method further includes terminating flow from the fuel pump to unlock and close the pressure responsive relief valve when the common rail fuel system is operating.

Description

Technical Field

[0001] The present invention relates generally to common rail fuel systems and, more particularly, to systems and methods for resetting a pressure relief valve of a common rail fuel system. Background Art

[0002] A common rail fuel system for an internal combustion engine may have a high-pressure fuel pump that provides fuel to the fuel rail at a specific pressure. The fuel system may also include a pressure relief valve for releasing undesirable high pressure in the common rail. These pressure relief valves may have a high-pressure trigger point that locks the valve open and a low-pressure reset point that unlocks the valve to a closed position. The high-pressure trigger point corresponds to a pressure higher than any normal operating pressure of the common rail. In some cases, after the pressure relief valve is triggered, the fuel pump may continue to pressurize the fuel to the common rail to keep the rail pressure above the low-pressure reset point required to unlock and close the pressure relief valve. Therefore, the pressure relief valve may remain open, and the fuel system may attempt to compensate for the open valve. This may occur, for example, when the fuel system control and monitoring system misdiagnoses the system state as experiencing a low-pressure event rather than a high-pressure event due to an unidentified lock opening of the pressure relief valve. This incorrect diagnosis of the rail state may therefore result in harmful and prolonged opening of the pressure relief valve, operating the engine at a lower rail pressure than required, and / or fuel pump inefficiency.

[0003] U.S. Patent No. 9,347,409 (“the '409 patent”) describes a method for controlling and regulating an internal combustion engine having a common rail fuel system including a passive pressure relief valve for discharging fuel from a rail into a fuel tank. The '409 patent describes that in a first stage of operation, when a rail pressure, proceeding from a steady-state rail pressure, exceeds a first threshold, the passive pressure relief valve is set to open. Subsequently, the pressure may drop below a second threshold and the relief valve may close. The first threshold represents a pressure level higher than the steady-state rail pressure and the second threshold represents a pressure level lower than the first threshold. During a time between exceeding the first threshold and falling below the second threshold, the open pressure relief valve is monitored. However, the '409 patent does not specifically relate to a system for identifying a misdiagnosed high pressure event in a fuel system.

[0004] The systems and methods of the present invention solve one or more of the above problems and / or other problems in the art. However, the scope of the present invention is defined by the appended claims, rather than by the ability to solve any specific problem. Summary of the invention

[0005] According to one aspect of the present invention, a method for controlling a common rail fuel system of an engine system is provided. The common rail fuel system includes a fuel pump, a fuel rail, a plurality of fuel injectors, and a pressure responsive release valve fluidly coupled to the fuel rail. The method includes identifying a pressure state of the fuel rail indicating that the pressure responsive release valve is in an open and locked state, the identification being based on detecting an increase and decrease in rail pressure within a threshold time period. The method also includes terminating flow from the fuel pump to unlock and close the pressure responsive release valve when the common rail fuel system is operating.

[0006] According to another aspect of the present invention, a common rail fuel system of an engine system includes a fuel pump, a fuel rail, a plurality of fuel injectors, a pressure responsive release valve fluidly coupled to the fuel rail, and a controller. The controller is configured to identify a pressure state of the fuel rail indicating that the pressure responsive release valve is in an open and locked state, the identification being based on detecting an increase and decrease in rail pressure within a threshold time period. The controller is also configured to terminate flow from the fuel pump to unlock and close the pressure release valve when the common rail fuel system is in operation.

[0007] According to another aspect of the present invention, a method of controlling a common rail fuel system of an engine system is provided. The common rail fuel system includes a fuel pump, a fuel rail, a plurality of fuel injectors, and a pressure responsive release valve fluidly coupled to the fuel rail. The method includes identifying a pressure state of the fuel rail indicating that the pressure responsive release valve is in an open and a closed state. The identification is based on detecting an increase and a decrease in rail pressure within a threshold time period, and the identification is initiated by detecting that the rail pressure decreases by a threshold amount within the threshold time period. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and, together with the description, serve to explain the principles of the disclosed embodiments.

[0009] Figure 1 is a system schematic diagram of a common rail fuel system of an internal combustion engine system according to aspects of the present invention.

[0010] Figure 2 yes Figure 1 Schematic diagram of various aspects of the control system of a common rail fuel system.

[0011] Figure 3 Provides descriptions for detecting and resetting Figure 1 A flow chart of an exemplary method for a pressure relief valve of a common rail fuel system.

[0012] Figure 4 It is a depiction Figure 1 A diagram of the operational aspects of the system. DETAILED DESCRIPTION

[0013] Both the foregoing general description and the following detailed description are exemplary and illustrative only and do not limit the claimed features. As used herein, the terms "comprises," "comprising," "has," "having," "includes," "including," or other variations thereof are intended to encompass a non-exclusive inclusion such that a process, method, article, or apparatus comprising a list of elements includes not only those elements but may also include other elements not expressly listed or inherent to such process, method, article, or apparatus. In the present invention, relative terms (e.g., "about," "substantially," and "approximately," etc.) are used to indicate possible variations of ±10% in the stated values ​​unless otherwise stated.

[0014] Figure 1 An internal combustion engine system is shown that includes a common rail fuel system 100. The common rail fuel system 100 may include a fuel tank or sump 102, a fuel pump 104, a common rail fuel 106, a pressure relief (or pressure limiting) valve 108, a rail pressure sensor 110, a plurality of fuel injectors 112, and a fuel rail control system 200 that includes an electronic controller 201. The common rail fuel system 100 may provide fuel to the internal combustion engine system, which in turn may drive a crankshaft to provide torque to one or more external systems (not shown).

[0015] The fuel pump 104 may be any type of fuel pump, such as an inlet metering fuel pump having a controllable inlet valve 105, for providing fuel at a desired pressure to the fuel rail 106. The common fuel rail 106 may be a plenum in the form of a pipe that is directly fluidly coupled to each fuel injector 112 for providing pressurized fuel to the fuel injectors 112. The rail pressure sensor 110 may be of conventional design for sensing fuel pressure within the common fuel rail 106 and providing the sensed pressure to the electronic controller 201. As will be described below with reference to Figure 2 Described in more detail, the electronic controller 201 may send and receive signals to and from the fuel pump 104 , the rail pressure sensor 110 , and the fuel injectors 112 , as well as other components of the engine system, to control the fuel pressure in the fuel rail 106 to a desired pressure based on, for example, desired power, regulation of engine emissions, etc.

[0016] The pressure relief valve 108 may be a pressure responsive relief valve that is directly fluidly connected to the common fuel rail 106 and may include, for example, a mechanical trigger system including, for example, a spring loaded valve and a latching element configured to open and remain open (or latched) in response to the rail pressure in the fuel rail 106 reaching a pressure threshold corresponding to an overpressure condition in the common fuel rail 106. The overpressure condition corresponds to a rail pressure that may be damaging. In the open and latched states of the pressure relief valve 108, the fuel fluid in the fuel rail 106 is connected to the low pressure passage 116, which connects the common fuel rail 106 to the fuel tank or sump 102, thereby reducing the pressure in the common fuel rail 106. Once opened and latched, the pressure relief valve 108 is designed to remain latched open until the pressure in the common fuel rail 106 is reduced to a valve reset pressure. In one example, the pressure relief valve may open and latch at a rail pressure of approximately 270 MPa, and may be closed (i.e., reset) at a rail pressure of approximately 60 MPa.

[0017] Now refer to Figure 2 , describing the fuel rail control system 200 in more detail. The fuel rail control system 200 includes a controller 201 that is communicatively coupled to or otherwise includes one or more modules or systems for performing one or more functions of the engine system and the common rail fuel system 100. The fuel rail control system 200 may include an input 210 in the form of data, signals, etc. and an output 220 in the form of data, signals, etc. For example, the controller 201 may be communicatively coupled to the rail pressure sensor 110 and may receive rail pressure data 212 therefrom. The controller 201 may be communicatively coupled to the fuel pump 104 and may receive fuel pump status data 214 regarding the operating state of the fuel pump 104. The controller 201 may be communicatively coupled to one or more of the plurality of fuel injectors 112 and may receive injector status data 216. The controller 201 may include a memory 202 and various modules, such as a pump control module 204, a derating control module 206, and a pressure monitoring module 208. In some embodiments, the controller 201 may include an accumulative sum counter 207 that provides a running count of consecutive values, and a high-speed buffer 209 that stores data for the controller 201, both of which will be discussed in more detail. The controller 201 may generate outputs including a pump control signal 222 that controls one or more functions of the fuel pump 104 and an injector control signal 224 that controls one or more functions of the one or more fuel injectors 112.

[0018] The controller 201 may include a single processor or multiple processors configured to receive input, display output, and generate commands to control the operation of components of the engine system including the common rail fuel system 100. The controller 201 may include or be associated with a memory, an auxiliary storage device, such as a processor of a central processing unit, a network interface, or any other device for performing tasks consistent with the present invention. The memory or auxiliary storage device included or associated with the controller 201 may store data and software to allow the controller 201 to perform its functions, including the following with respect to the method 300 ( Figure 3 ) describes the functionality and Figure 4 The functionality of system 100 is described.

[0019] Industrial Applicability

[0020] The disclosed aspects of the common rail fuel system 100 of the present invention may be used, for example, to control pressure within the fuel rail 106. For example, the disclosed system may determine, via the fuel rail control system 200, whether the mechanically operated high pressure relief valve 108 has been opened and closed due to high pressure conditions in the common rail 106, and modify the operation of the common rail fuel system 100 based on the determination.

[0021] Reference Figure 3 , a method 300 of operating an internal combustion engine system including a common rail fuel system 100 is shown. The described method begins by operating the engine and the common rail fuel system 100 within a normal operating range, such as operating the engine with a common rail pressure within a desired operating range (step 302). In particular, the normal or desired operating range of the common rail fuel system 100 may include, for example, a rail pressure between a lower limit of 50 MPa and an upper limit of 230 MPa.

[0022] As the engine and common rail fuel system 100 operate, the control system 200 may sense system parameters, such as input 210 ( Figure 2 ). Specifically, the control system 200 may monitor the rail pressure data 212 from the rail pressure sensor 110 and store it in, for example, the high-speed buffer 209 (step 304), which will be explained in more detail below. The control system 200 may also monitor and sense or receive other parameters during operation of the common rail fuel system 100, such as additional inputs 210 including fuel pump status data 214 and fuel injector status data 216. This additional data may be stored in the memory 202 and / or other modules of the controller 201, and thus may be used to control one or more functions of the common rail fuel system 100.

[0023] The control system 200 may monitor the rail pressure data 212 for an unexpected, sudden rail pressure drop. For example, the control system 200 may be configured to detect when the rail pressure exceeds a rate of change threshold stored in the control system 200. Such a rate of change corresponding to an unexpected, sudden rail pressure drop may be, for example, a rail pressure drop of greater than 100 MPa in less than 1 second. However, this drop level is merely exemplary, and other pressure drops or drop rates may be used as an indication of an unexpected, sudden rail pressure drop, such as a threshold corresponding to a difference between an expected rail pressure and a measured rail pressure for a threshold amount of time. When the control system 200 detects such an unexpected, sudden rail pressure drop, the control system initiates a derating of the engine (step 306), and accordingly sends the fuel pump and fuel injector control signals 222, 224 based on the derating.

[0024] This detected, unexpected and sudden rail pressure drop (step 306) can be caused by either of two different conditions or events. The first potential cause includes the rail pressure exceeding the pressure threshold of the high pressure relief valve 108, thereby opening and closing the pressure relief valve 108 to release the high rail pressure. The opening and closing of the pressure relief valve 108 will open the fuel rail 106 to exhaust and thus suddenly reduce the pressure in the fuel rail 106. This first cause is referred to as a high pressure event in this article. The second potential cause of the detected, unexpected and sudden rail pressure drop includes one or more other system failures, including a leak in the fuel rail 106 or a failure of the fuel pump 104. This second cause is referred to as a low pressure rail event. The method 300 described herein can be used to help diagnose the cause of the sudden rail pressure drop in the common rail fuel system 100 - whether the cause is a high pressure rail event or a low pressure rail event. Correctly diagnosing a low pressure rail event (e.g., a system leak) versus a high pressure rail event with an open and latched high pressure relief valve 108 may mean the difference between (a) complete shutdown of the engine system or highly derated engine operation (in the case of a leak) and (b) continued engine operation at a less derated engine operation upon resetting of the open and latched pressure relief valve 108. Thus, such a diagnosis may increase system operational capabilities.

[0025] After detecting a sudden rail pressure drop and initiating engine derating (step 306), the control system 200 may check the previous rail pressure (before the sudden rail pressure drop was detected) stored in the high-speed buffer 209 (step 308) to diagnose the cause of the sudden rail pressure drop. Specifically, the control system 200 may check the previous rail pressure to determine whether the pressure in the rail 106 increased immediately before the sudden rail pressure drop was detected (step 310). Such a pressure increase may be identified, for example, by a rail pressure that is equal to or above a threshold rail pressure for triggering the pressure relief valve 108 - a rail pressure corresponding to an overpressure condition in the common fuel rail 106 (e.g., 270 MPa or greater). It should be understood that the identified pressure increase immediately prior to the detected sudden rail pressure drop may alternatively correspond to a positive change in rail pressure (e.g., 5 MPa, 10 MPa, 20 MPa, etc.) immediately prior to the sudden rail pressure drop. As will be described in conjunction with Figure 4 As shown, in some cases, this pressure increase may only last for a short time, such as a fraction of a second, before the pressure relief valve 108 opens and latches, resulting in a sudden rail pressure drop.

[0026] Therefore, the control system 200 identifies the pressure state of the fuel rail 106 indicating that the pressure relief valve 108 is in the open and closed states, the identification is based on detecting the increase and decrease of the rail pressure within the threshold time period (steps 306, 310), and the identification is initiated by detecting that the rail pressure decreases by a threshold amount within the threshold time period (step 306), and then detecting the increase of the rail pressure based on the rail pressure data in the buffer. However, the increase of the rail pressure occurs before the decrease of the rail pressure, such as Figure 4 As shown below.

[0027] If the control system 200 checks the previous rail pressure (step 306) and determines that the rail pressure did not increase immediately before the detected sudden rail pressure drop (step 310-no), the control system 200 will diagnose the system as having a low pressure rail event (step 312), which is caused by, for example, a system leak, a fuel pump failure, or other failure. In response to this determination, the control system 200 continues the initiated engine de-rating (step 306) to a determined de-rating level corresponding to the low pressure rail event (step 314). For example, the de-rating level may include a complete engine shutdown or de-rating or limp home operation sufficient to prevent damage to system components during operation of the system in an impaired state. Such a limp home de-rating may, for example, be greater than a 50% de-rating, such as a 60% de-rating.

[0028] However, if checking the rail pressure in the high speed buffer 209 at step 310 indicates that the rail pressure did rise above the opening and closing pressures of the pressure relief valve 108 before the rail pressure decreased (step 310-yes), the system will identify the rail pressure decrease as a high pressure event, corresponding to a high pressure fault condition, at step 316. As provided in steps 318-324, further analysis of this fault condition will be required to determine how to further control the common rail fuel system 100.

[0029] After determining that the reduction in rail pressure is based on a high pressure event (step 316), at step 318, the system monitors the rail pressure to determine whether the rail pressure remains within a pressure relief valve regulation region ("PRV regulation region"). The PRV regulation region corresponds to a rail pressure range having a lower limit greater than the reset pressure of the pressure relief valve 108 (e.g., 60 MPa) and an upper limit less than the opening and closing pressures of the pressure relief valve 108 (e.g., 270 MPa). For example, the common rail fuel system 100 may attempt to correct a lower than desired rail pressure (based on an unidentified opening and closing of the pressure relief valve 108). In this case, the rail pressure may be approximately 90 MPa, greater than the pressure relief valve reset pressure of approximately 60 MPa, and less than the opening and closing pressures of approximately 270 MPa. The controller 201 may check the rail pressure for a period of time (e.g., 1 second, 5 seconds, 10 seconds, etc.) via the pressure monitoring module 208 to determine whether the rail pressure remains within the PRV regulation region. Maintaining the fuel rail 106 pressure within the PRV regulation region indicates that the system is attempting to maintain the desired rail pressure but has not yet recognized that the pressure relief valve 108 is open and latched.

[0030] When a high pressure rail event has been identified (step 316), and the rail pressure is not within the PRV regulation zone (step 318-No), the operation of the common rail fuel system 100 is considered to be faulty, such that an engine shutdown or other engine reduction or de-rating is required (step 326). The inability of the common rail fuel system 100 to maintain a pressure within the PRV regulation zone may indicate a system fault that is not diagnosable using only the system described herein. For example, a constant fuel rail pressure below the PRV regulation zone may indicate a leak in the fuel rail supply line, a failure of the high pressure fuel pump, or other system fault. A constant fuel rail pressure above the PRV regulation zone may indicate a pressure sensor failure or other system fault.

[0031] If the common rail fuel system 100 is operating in the PRV regulation region (step 314-yes), the system may temporarily interrupt or terminate flow from the fuel pump 104 (e.g., for less than one second, or approximately 100 milliseconds) at step 320. Such interruption of the fuel pump 104 may be achieved, for example, by terminating the pumping / output of fuel from the fuel pump 104, such as by sending a command 222 to the fuel pump 104 to stop or limit the flow of fuel entering the pump via the inlet metering valve 105, or by terminating power to the pump 104. When the common rail fuel system is otherwise operating, a reduction in the output of the fuel pump 104 occurs, and the pressure within the fuel rail 106 may be reduced to below the reset pressure of the pressure relief valve 108 (approximately 60 MPa), thereby allowing the pressure relief valve 108 to close and allowing the common rail fuel system 100 to restore integrity and operate at the desired rail pressure. Termination of pump flow may be controlled by, for example, the pump control module 204, which may receive fuel pump status data 214 (e.g., fuel pump is in an on / off state, etc.) from the fuel pump 104 or the state of the fuel pump inlet metering valve 105 (e.g., fuel pump inlet metering valve open / closed, etc.). Once flow from the fuel pump 104 is terminated, the common rail fuel system 100 may continue to operate to inject fuel from the common rail 106 to the cylinders (not shown) through the fuel injectors 112. As flow from the fuel pump 104 is terminated and the fuel injectors 112 provide fuel to the cylinders (not shown), the pressure in the common rail may decrease rapidly, thereby allowing the high pressure relief valve 108 to be opened and closed. When the relief valve 108 is closed or reset, fuel no longer flows from the common rail 106 to the sump 102 through the relief valve 108. With the pressure relief valve 108 in the closed state, fuel flow from the fuel pump may be resumed at step 322 (eg, the fuel pump 104 may be re-energized, or the pump inlet metering valve 105 may be reopened, etc.).

[0032] After the high pressure relief valve 108 has been closed / reset, the engine and common rail fuel system 100 may continue to be at a partially derated level, such as a determined derated level corresponding to the high pressure rail event level (step 324). The high pressure rail event level derated level may be a system operating level at a partially derated level, which may allow system operation at a level sufficient for some engine operations, but may allow further system diagnostics or may prevent subsequent or further damage to the engine. In some embodiments, the partially derated state associated with a high pressure rail event may be a higher operating state than a fully derated state, such as a derated level triggered by the identification of a low pressure rail event. However, even if interrupting the pump supply successfully closes the pressure relief valve 108 and returns the rail pressure to a desired level or close to a desired level, the system may continue to operate in a partially derated state until a full diagnostic or system state can be determined. For example, the high pressure rail event derated may operate the engine at a 40% derated, which may correspond to approximately 80% of the engine capacity, until diagnostics can be performed. As described above, the derated engine operating state is higher than the engine derate associated with the identification of the low pressure rail event (step 312), which can be, for example, a 60% derate or greater derate. The lower derate associated with the high pressure rail event can allow greater operational versatility than the low pressure rail event. In addition, in one aspect, the continued operation of the machine at the lower derate associated with the high pressure rail event can be variable, and if no further sudden decrease in rail pressure is detected, the derate can be reduced.

[0033] Reference Figure 4 , an example of the operation of the common rail fuel system 100 is shown in a graph 400. The graph 400 includes a plurality of graphs along the x-axis which represents the time course (in seconds) when a high pressure fault, opening and latching, and closing or resetting of the high pressure relief valve 108 occurs. Figure 4 On the y-axis are actual or measured rail pressure values ​​402 and desired rail pressure values ​​410 of the common rail 106 , engine speed 404 , a torque limit 406 of the engine system, and a de-rating percentage state 408 of the engine system.

[0034] As time progresses along the x-axis, the engine system 100 operates in a steady state condition, where the common rail pressure (as measured by the common rail pressure sensor 110) is in a steady state condition until just after 10 seconds, when the high pressure condition (at point 402a) trips the high pressure relief valve 108 and the relief valve 108 opens and remains latched open. Upon opening and latching the high pressure relief valve 108, the fuel pressure immediately drops to a lower pressure steady state condition (at point 402b). In this steady state low pressure condition, the volume of fuel escaping the fuel rail through the pressure relief valve 108 is compensated by the volume of fuel provided to the fuel rail 108 from the fuel pump 104. As described above, the steady state rail pressure 402b may be approximately 90 MPa and greater than the pressure relief valve reset pressure of approximately 60 MPa within the PRV regulation region, and less than the opening and latching pressures of approximately 270 MPa.

[0035] At point 402c, the pressure in the fuel rail has been monitored long enough to be considered steady state, and the use of the cumulative sum counter has determined that the rail pressure has been within the PRV regulation region long enough that the low rail pressure condition can be determined as a high pressure rail event requiring interruption of the fuel supply from the fuel pump 104. At point 402c, flow from the fuel pump 104 is briefly interrupted (e.g., less than 1 second), as shown by the drop in actual fuel pressure 402 at approximately 15 seconds on the graph.

[0036] Once flow from the fuel pump 104 to the common rail 106 is interrupted while the engine system continues to operate, the pressure in the common fuel rail drops rapidly as fuel from the fuel injectors 112 continues to flow to the engine cylinders (not shown). For example, it may take only one or two cycles of the engine system 100 for the fuel to drop below the reset pressure to close the pressure relief valve 108. Flow from the fuel pump 104 through the fuel injectors 112 to the cylinders may then be resumed (point 402d).

[0037] Once the rail pressure has dropped below the reset or closing pressure of the pressure relief valve 108 and the pressure relief valve is unlocked to close, flow from the pump can be restored. Figure 4 As shown, once pump flow is restarted, the pressure in the common rail 106 rises rapidly. The rise in pressure to the desired pressure (at point 402e) indicates a successful reset of the high pressure relief valve, and indicates that the integrity of the common rail system, at least with respect to the relief valve 108, is intact. The desired rail pressure determined as a result of the high pressure state after determining the low pressure in the fuel rail may be a lower desired pressure than the desired pressure before determining the low pressure state. This is because the system may be operating in a derated state as described above. The actual pressure in the common rail 106 eventually stabilizes to the desired pressure (e.g., derated pressure) and the steady state state (at point 402f).

[0038] The operation of the system 100 in the derated state after the pressure transient is described with reference to the graph of the torque limit 406 and the derated state 408. Operation in the derated state may refer to the step of the system 100 limiting the engine output upon detecting the sudden rail pressure reduction detected at point 402b in order to avoid operation of the system that may have one or more undiagnosed system faults (e.g., a slow, difficult to detect leak that may be exacerbated by operation of the system in a fully rated state, which is normal operation of the machine until and at its full normal operating capacity, etc.). More specifically, once the initial low pressure state is detected at point 402b, the derate control module 208 may begin to derate the engine and may continue to derate the engine to a high derated state (e.g., a 60% derate corresponding to a low pressure rail event). At the same time, the engine system torque limit 406 is reduced. Reducing the power of the engine system helps regulate the pressure in the fuel rail 106, which at least at point 402b may be considered to have a fuel leak or other fault in the system. However, in the depicted embodiment, the pressure relief valve 108 is reset at point 402d, which allows the pressure in the common rail to return to the desired rail pressure, albeit at a derated level of the desired rail pressure. With the pressure relief valve 108 closed and the rail pressure returning to the desired rail pressure at the derated level, the engine system 100 may operate at a lower derated (e.g., 40% derated as a result of a high pressure rail event), as indicated by the flat portions of the graphs of the torque limit 406 and derated state 408, respectively, after point 402d. This reduced operating capacity may be desirable so that the engine system 100 is not operating at full capacity when conditions that reduce the pressure in the common rail may exist (e.g., in the event that there are two simultaneous faults in the system, one producing a high pressure condition that trips the high pressure relief valve, and one involving, for example, a slow fuel leak).

[0039] The present invention provides a system for identifying or diagnosing the operation of a common rail fuel system 100 having an open and latched pressure relief valve 108 and customizing engine derating based on the common rail fuel system 100. In addition, the present invention avoids prolonged operation of the pressure relief valve 108 in an open and latched state that could damage the valve. Still further, the disclosed system avoids a complete engine system shutdown to reset the pressure relief valve 108.

[0040] It is obvious to those skilled in the art that various modifications and variations may be made to the disclosed system without departing from the scope of the present invention. Other embodiments of the system will be apparent to those skilled in the art by consideration of the specification and practice of the methods disclosed herein. The specification and examples are intended to be considered exemplary only, with the true scope of the present invention being indicated by the appended claims and their equivalents.

Claims

1. A method of controlling a common rail fuel system of an engine system, the common rail fuel system having a fuel pump, a fuel rail, a plurality of fuel injectors, and a pressure responsive release valve fluidly coupled to the fuel rail, the method comprising: identifying a pressure state of the fuel rail indicative of an open and a latched state of the pressure responsive relief valve, the identification being based on detecting an increase and a decrease in rail pressure within a threshold time period; as well as When the common rail fuel system is operating, flow from the fuel pump is terminated to unlatch and close the pressure responsive relief valve. 2 . The method of claim 1 , wherein said identifying is initiated by detecting a rail pressure decrease by a threshold amount within a threshold time period. 3 . The method of claim 2 , wherein the detection of the increase in rail pressure is based on rail pressure data in a buffer. 4 . The method of claim 3 , wherein the increase in rail pressure occurs before the decrease in rail pressure. 5 . The method of claim 4 , further comprising sensing rail pressure between valve opening and valve reset pressures of the pressure responsive relief valve prior to terminating flow from the fuel pump.

6. The method of claim 5, wherein the valve opening pressure is about 270 MPa and the valve reset pressure is about 60 MPa. 7 . The method of claim 5 , further comprising resuming the supply of fuel from the fuel pump less than one second after terminating flow. 8 . The method of claim 6 , further comprising de-rating the engine system based on identification of a fuel rail pressure condition indicative of a pressure responsive relief valve being in an open and latched state. 9 . The method of claim 8 , further comprising injecting fuel with the plurality of fuel injectors while terminating fuel flow from the fuel pump.

10. A common rail fuel system for an engine system, comprising: Fuel pump, Fuel rail, Multiple fuel injectors, a pressure responsive relief valve fluidly coupled to the fuel rail, and A controller configured to: identifying a pressure state of the fuel rail indicative of the pressure responsive relief valve being in open and latched states, the identification being based on detecting increases and decreases in rail pressure within a threshold time period, and Flow from the fuel pump is terminated while the common rail fuel system is operating to unlatch and close the pressure relief valve.

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