Fuel system management during cylinder deactivation operation

Abstract

The invention relates to fuel system management during cylinder deactivation operation. A method for operating an engine fueling system to manage fuel in an accumulator supplying fuel to an engine including a plurality of cylinders includes: monitoring a fuel load in the accumulator; determining that the engine is operating in a cylinder deactivation mode, such as a flash mode, during which one or more fueling events to one or more of the cylinders are skipped; and during the cylinder deactivation mode operation, controlling the supply of fuel from the fuel pump to the accumulator. In an embodiment, controlling the supply of fuel includes: if a monitored fuel load is less than or equal to a first fuel load, causing fuel to be supplied from a fuel pump to an accumulator; and causing fuel not to be supplied from the fuel pump to the accumulator if the monitored fuel load is greater than the first load value. Controlling the supply of fuel may include controlling the supply of fuel during each fuel addition event cycle of each deactivated cylinder.

Description

[0001] This invention is a divisional application of the Chinese invention patent application with application number 202111190663.0, application date October 13, 2021, and invention name “Fuel System Management During Cylinder Deactivation Operation”.

[0002] Related Applications

[0003] This application claims priority to U.S. Provisional Patent Application No. 63 / 092,613, filed on October 16, 2020, the subject matter of which is incorporated herein by reference. Technical Field

[0004] The present disclosure generally relates to a fuel system for an engine operating in a cylinder deactivation mode. Background Art

[0005] Engine systems are generally known. However, there remains a continuing need for improved engine systems. In particular, there is a need for engine systems that provide enhanced efficiency. These types of engine systems that provide enhanced management of noise, vibration and harshness (NVH) would be particularly advantageous. Summary of the invention

[0006] The disclosed embodiments include a fuel addition system that provides efficient operation of an engine system. Noise, vibration, and harshness (NVH) of the engine system can be enhanced by using a fuel addition system.

[0007] Embodiments include a method for operating an engine fuel addition system to manage fuel in an accumulator, wherein the accumulator supplies fuel to an engine including a plurality of cylinders. An example of the method includes: monitoring a fuel load in the accumulator; determining that the engine is operating in a cylinder deactivation mode during which one or more fuel addition events to one or more of the cylinders are skipped; and controlling the supply of fuel from a fuel pump to the accumulator during the cylinder deactivation mode operation by: causing fuel to be supplied from the fuel pump to the accumulator if the monitored fuel load is less than or equal to a first load value; and causing fuel not to be supplied from the fuel pump to the accumulator if the monitored fuel load is greater than the first load value.

[0008] As an example of these embodiments, supplying fuel from the fuel pump to the accumulator may include actuating a valve to supply the fuel from the fuel pump to the accumulator. Not supplying fuel from the fuel pump to the accumulator may include actuating a valve to prevent fuel from being supplied from the fuel pump to the accumulator. Actuating the valve to prevent fuel from being supplied from the fuel pump to the accumulator may include actuating the valve to recirculate fuel from the fuel pump.

[0009] As an example of these embodiments, determining that the engine is operating in a cylinder deactivation mode may include determining that the engine is operating in a spark mode (and optionally a dynamic spark mode). Controlling the supply of fuel may include controlling the supply of fuel during each fuel addition event cycle of each deactivated cylinder.

[0010] In any of these embodiments, the first load value may be a value representing a minimum operating load.

[0011] Examples of these implementations may also include determining that an incremental engine load is requested; and when an incremental engine load is requested, during the cylinder deactivation mode of operation, controlling the supply of fuel from the fuel pump to the accumulator by: supplying fuel from the fuel pump to the accumulator if the monitored fuel load is less than or equal to a second load value, and wherein the second load value is greater than the first load value; and not supplying fuel from the fuel pump to the accumulator if the monitored fuel load is greater than the second load value. The second load value may be a value representing a maximum operating load.

[0012] As an example of these embodiments, monitoring the fuel load in the accumulator may include monitoring a fuel pressure in the accumulator, and the first load value and / or the second load value are pressure values.

[0013] As an example of these implementations, determining that the engine is operating in a cylinder deactivation mode may include receiving a signal indicative of the cylinder deactivation mode operation. Receiving the signal indicative of the cylinder deactivation mode operation may include receiving a signal indicative of respective skip fueling events for respective deactivated cylinders.

[0014] Embodiments also include a method for operating an engine fuel addition system to manage fuel in an accumulator, wherein the accumulator supplies fuel to an engine including a plurality of cylinders. An example of the method includes: monitoring a fuel load in the accumulator; determining that the engine is operating in a cylinder deactivation mode during which one or more fuel addition events to one or more of the cylinders are skipped; determining that an incremental engine load is requested when the engine is operating in the cylinder deactivation mode; and when an incremental engine load is requested during operation in the cylinder deactivation mode, controlling the supply of fuel from a fuel pump to the accumulator by: if the monitored fuel load is less than or equal to a second load value, causing fuel to be supplied from the fuel pump to the accumulator, wherein the second load value is greater than the first load value, the first load value defining an operating load of the accumulator; and if the monitored fuel load is greater than the second load value, causing fuel to not be supplied from the fuel pump to the accumulator.

[0015] As an example of these embodiments, the first load value may define an operational minimum load value of the accumulator. The second load value may be a value representing a maximum operational load.

[0016] As an example of these embodiments, supplying fuel from the fuel pump to the accumulator may include actuating a valve to supply the fuel from the fuel pump to the accumulator. Not supplying fuel from the fuel pump to the accumulator may include actuating a valve to prevent fuel from being supplied from the fuel pump to the accumulator. Actuating the valve to prevent fuel from being supplied from the fuel pump to the accumulator may include actuating the valve to recirculate fuel from the fuel pump.

[0017] As an example of these embodiments, determining that the engine is operating in a cylinder deactivation mode includes: determining that the engine is operating in a spark mode (optionally a dynamic spark mode); and controlling the supply of fuel includes controlling the supply of fuel during each fuel addition event cycle of each deactivated cylinder.

[0018] As an example of these embodiments, monitoring the fuel load in the accumulator may include monitoring a fuel pressure in the accumulator, and the first load value and / or the second load value are pressure values.

[0019] As an example of these embodiments, determining that the engine is operating in a cylinder deactivation mode may include receiving a signal indicative of the cylinder deactivation mode operation; and determining that an incremental engine load is requested may include receiving a signal indicative of an incremental engine load request. Receiving a signal indicative of cylinder deactivation mode operation may include receiving a signal indicative of respective skipped fueling events for respective deactivated cylinders.

[0020] Embodiments include an engine control unit configured to implement any and all of the exemplary methods described above. Embodiments include an engine fuel addition system of the engine control unit described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic diagram of an engine system including a fuel addition system according to an embodiment.

[0022] Figure 2 is a cross-sectional view of a pumping unit of a fuel adding system according to an embodiment.

[0023] Figure 3 is a schematic view of components of an engine control unit (ECU) according to an embodiment.

[0024] Figure 4 is a flowchart of a cylinder deactivation mode accumulator fuel addition control method according to an embodiment. DETAILED DESCRIPTION

[0025] Figure 1 1 is a schematic view of a vehicle engine system 8 including a fuel addition system 10 and an internal combustion engine 12 according to an embodiment. As shown, the fuel addition system 10 includes a fuel pump 14, a common rail fuel accumulator 16, a plurality of fuel injectors 18, and an engine control unit (ECU) 20. The engine 12 includes a plurality of cylinders 22, in which a plurality of pistons 24 reciprocate under the power provided by the combustion of fuel, thereby rotating a crankshaft 26 via a corresponding plurality of connecting rods 28. The fuel pump 14 (shown in this example as having two pumping elements or units 30) receives fuel from a fuel source 31, pressurizes the fuel, and provides the pressurized fuel to the accumulator 16. Each pumping unit 30 includes a metering valve 33 that controls the flow of fuel into and out of the pumping unit. As is well known in the art, the fuel injectors 18 (which are coupled to the accumulator 16 under the control of the ECU 20 and receive fuel from the accumulator 16) deliver fuel (also under the control of the ECU) to the cylinders 22 at specific times during the engine cycle. Operator controls 35 , which may include, for example, a throttle, are coupled to ECU 20 .

[0026] The ECU 20 receives a signal indicative of the amount of fuel or load in the accumulator 16. The illustrated embodiment of the controller 20 monitors pressure measurements from a pressure sensor 36 coupled to the accumulator 16. The pressure measurements are indicative of the pressure of the fuel in the accumulator 16.

[0027] As described in more detail below, the ECU 20 is configured to control the operation of the engine system 8 in one or more cylinder deactivation modes. In connection with the cylinder deactivation control, the ECU 20 controls the operation of the metering valve 33 to manage or optimize the load or pressure of the fuel in the accumulator 16. The parasitic load on the engine 12 can be managed (e.g., increased or decreased) to optimize the operation of the engine system 8. The thermal management of the engine system 8 and / or other components of the vehicle or system incorporating the engine system (such as an exhaust aftertreatment system) can be optimized. Overpressure events in the accumulator 16 can be eliminated or minimized. Undesirable noise, vibration, and harshness (NVH) of the motor system 8 can also be reduced.

[0028] Cylinder deactivation modes and associated control algorithms are well known and disclosed, for example, in U.S. Patent Application Publication No. 2020 / 0218258 to Subramanian et al., the entire disclosure of which is incorporated herein for all purposes. One such cylinder deactivation mode is sometimes referred to as fixed mode deactivation. During a fixed mode deactivation, a specified group of one or more cylinders of the engine are deactivated simultaneously for a period of time when it is necessary to reduce the engine displacement. As long as the cylinder is deactivated, fuel is not delivered to the deactivated cylinder. Another known cylinder deactivation mode that changes the effective displacement of the engine is sometimes referred to as a skip fire deactivation. Skip fire deactivation contemplates skipping fuel addition events and ignition of certain cylinders during selected opportunities. For example, a particular cylinder may be ignited during one engine cycle, may be skipped during the next engine cycle, and may be skipped or ignited during a subsequent engine cycle. Skip fire engine operation can be distinguished from fixed mode deactivation, in which a specified group of cylinders is deactivated substantially simultaneously and remains deactivated as long as the engine remains in the same displacement operating mode. During the skip fire mode operation, the engine control unit can individually control the associated fuel addition events and ignition of each cylinder during each cycle of the cylinder. For example, during the cylinder deactivation mode operation, which is sometimes referred to as dynamic skip mode operation, the fuel addition event and ignition decisions for each cylinder (i.e., whether to skip or fire a particular cylinder during a particular working cycle) are made in real time - typically immediately before the start of the working cycle, and are typically made at individual cylinder fuel addition events and ignition timings based on the individual cylinder fuel addition events and ignition timings. The present disclosure contemplates the use of any known or other conventional cylinder deactivation control mode by the engine system 8.

[0029] Figure 2is a schematic view of a pumping unit 30 and an associated inlet or metering valve 33 according to an embodiment. As shown, the pumping unit 30 includes a housing 38, a tappet 40, and a roller 42. A pumping chamber 52 is in fluid communication with an inlet 53 and an outlet 55. The inlet 53 is configured to be fluidly coupled to the fuel source 31, and the outlet 55 is configured to be fluidly coupled to the common rail fuel accumulator 16. In an embodiment, the fuel pump 14 is a high pressure fuel pump, and the pumping unit 30 can be coupled to the fuel source 31 via a low pressure fuel pump, as is generally known or otherwise conventional and generally disclosed, for example, in U.S. Patent No. 9,157,393 to Fulton et al.

[0030] The metering valve 33 includes a solenoid 35, an actuating rod 37, and a base 39. The base 39 is positioned in the pumping chamber 52 and is configured to reciprocate between an open position and a closed position in relation to the operation of the valve. In response to a valve control signal provided by the ECU 20, the base 39 is actuated and driven between an open position and a closed position by the solenoid 35 via the actuating rod 37. When the base 39 is in the open position, the inlet 53 is in fluid communication with the pumping chamber 52, thereby allowing fuel to flow between the inlet and the pumping chamber. When the base 39 is in the closed position, the inlet 53 is fluidly sealed with the pumping chamber 52, thereby preventing fuel from flowing between the inlet 53 and the pumping chamber 52. The metering valve 33 acts as a recirculation valve, and when the base 39 is actuated to its open position, the fuel is recirculated back to the inlet 53 and toward the fuel source 31. In an embodiment, the valve 33 is a normally open valve, and the base 39 is biased to an open position by a spring 41. Other embodiments include other types of valves, such as a normally closed valve.

[0031] In the illustrated embodiment, the solenoid 35 of the metering valve 33 is shown as being disposed at the upper end of the housing 38. The outlet valve 48 is also disposed in the housing 38, between the pumping chamber 52 and the outlet 55. The housing 38 includes a barrel 50 that defines the pumping chamber 52. A plunger 54 coupled to the tappet 40 reciprocates in the pumping chamber 52, compressing any fuel in the pumping chamber during an upward pumping stroke (when the seat 39 is in the closed position) to be delivered through the outlet valve 48 to the outlet 55, and from the outlet 55 to the accumulator 16. When the seat 39 is in the open position, fuel is delivered to the pumping chamber 52 through the metering valve 33 during the downward filling stroke of the plunger 54.

[0032] The reciprocating motion of the plunger 54 is controlled by a cam shaft 56 (which is connected to Figure 1The camshaft 56 is powered by the rotational movement of the crankshaft 26 (shown in FIG. 1 ) and the downward biasing force of the return spring 58. As the camshaft 56 rotates, an eccentric lobe 60 mounted to the camshaft 56 also rotates. Due to the biasing force of the spring 58, the roller 42 remains in contact with the lobe 60. Therefore, during half a revolution of the camshaft 56, the lobe 60 pushes the roller 42 (and the tappet 40 and the plunger 54) upward, and during the other half a revolution, the spring 58 pushes the roller 42 (and the tappet 40 and the plunger 54) downward into contact with the lobe 60.

[0033] The operation of the metering valve 33 is controlled by the ECU 20, which actuates the valve to an open state and a closed state according to various control methods described below, so that the pumping unit 30 can controllably deliver a certain amount of fuel to the accumulator 16. When the metering valve is in the open state, the ECU 20 actuates the metering valve 33 to place the seat 39 in the open position and prevent fuel from flowing to the accumulator 16 during a pumping event. When the metering valve is actuated to the closed state, the ECU 20 actuates the metering valve 33 to reciprocate the seat 39 between the closed position and the open position and pump fuel to the accumulator 16 during a pumping event.

[0034] Although for the purposes of this example Figure 2 Only one pumping unit 30 is shown, but the second pumping unit and any additional pumping units 30 may be combined with Figure 2 The pumping units described are substantially the same or similar. U.S. Patent Application Publication No. 2019 / 0331053 of Benson discloses an example of a fuel pump 14 that can be used in an embodiment, and the entire disclosure of the Benson publication is incorporated herein in its entirety for all purposes. In an embodiment, the plungers (such as 54) of the two pumping units 30 have the same surface area. The inlets (such as 53) of the two pumping units 30 can be fluidly coupled to each other and / or fluidly coupled to any low-pressure pump system (not shown). Either or both of the metering valves 33 of the two pumping units 30 can be independently actuated by the ECU 20 to its open state and / or closed state to control the fuel pressure in the accumulator 16.

[0035] Figure 3is a schematic view of exemplary functional components of the ECU 20 according to an embodiment. The illustrated embodiment includes a processing system 70, which includes a processing component 72 and a storage component 74 connected by a bus 76. The processing component 72 may include, for example, one or more central processing units (CPUs) 78 that provide processing functions for the fuel addition system 10. The storage component 74 may include a RAM memory 80, a hard disk drive (HDD) and / or a solid state drive (SSD) memory 82, thereby providing information and other data storage functions for the fuel addition system 10. For example, an operating system and other software used by the processing component 72 to implement cylinder deactivation mode control and an associated accumulator fuel pressure optimization method and algorithm of the system 10 as described herein may be stored in the storage component 74. The components of the ECU 20 may be implemented as a programmed microprocessor, an application specific integrated circuit (ASIC), a controller and / or discrete circuit components. Other embodiments of the ECU 20 are implemented using other conventional or other known systems or devices.

[0036] Figure 3 The illustrated embodiment of the ECU 20 also includes an input / output (I / O) port 84 through which the ECU 20 can receive and send information or other data. For example, in an embodiment, the ECU 20 can be coupled to an operator control 35 via the input / output port 84, such as a component that provides information representative of a command such as an operator actuating a throttle of the engine system 8 or an operator selecting a cylinder deactivation mode. A signal representing the pressure in the common rail fuel accumulator 16 or other information provided by the pressure sensor 36 can be coupled to the ECU 20 via the input / output port 84. Control signals generated and provided by the ECU 20 to control actuation of the metering valve 33 and the fuel injector 18 can be coupled via the input / output port 84. The input / output port 84 can also be coupled to other components (not shown) of the engine system 8. For example, in an embodiment, ECU 20 may be connected via input / output port 84 to receive information from and / or provide control signals to a transmission (e.g., to control gear shifting) and / or an exhaust aftertreatment system of an engine system (not shown).

[0037] The common rail fuel accumulator 16 is a reservoir for pressurized fuel that is coupled to each of the fuel injectors 18. In response to control signals from the ECU 20, the fuel injectors 18 deliver fuel from the accumulator 16 to the associated cylinders 22. The pressure within the accumulator 16 is monitored by the ECU 20 based on signals received from the pressure sensor 36. Based on the monitored pressure and a pressure management algorithm associated with the cylinder deactivation mode, the ECU 20 actuates one or more metering valves 33 to maintain the pressure within the accumulator 16 at certain desired or predetermined levels.

[0038] In an embodiment, the ECU 20 may operate the fuel addition system 10 during certain time periods to maintain the fuel pressure within the common rail fuel accumulator 16 at a predetermined first or minimum (MIN) pressure level. The MIN pressure level may, for example, be an operating pressure level sufficient to enable the engine 12 to adequately respond to an expected fuel addition command during typical normal or regular operation of the engine system 8. In an embodiment, the ECU 20 may operate the fuel addition system 10 during certain time periods to maintain the fuel pressure within the accumulator 16 at a second pressure level or a maximum (MAX) pressure level. The MAX pressure level may be a level greater than the MIN level, and in an embodiment is a level that allows the engine 12 to adequately respond to relatively short-term or incremental fuel addition commands that require a greater amount of fuel than those required during normal or regular operation of the engine system 8. For example, in response to an operator command (such as a throttle actuation) that requires a relatively high amount of engine power (such as high acceleration), or in response to other operations of the engine system 8 controlled by the ECU 20 that may benefit from an incremental and greater than normal power output from the engine 12 (such as a gear shift event or an exhaust aftertreatment system actuation), the ECU may operate the fuel addition system 10 to maintain the fuel pressure within the accumulator 16 at a MAX level. In an embodiment, the MAX level is a maximum operating level that is less than the maximum pressure specification or rating of the accumulator 16. Embodiments of the accumulator 16 may also include a high pressure relief valve (such as a check valve (not shown)) to relieve any pressure within the accumulator that may exceed the maximum rated pressure of the accumulator.

[0039] Figure 41 is a schematic diagram of a cylinder deactivation mode accumulator fuel addition control method 100 according to an embodiment, by which the fuel addition system 10 may be operated. The ECU 20 may provide control functionality for the method 100. As shown in step 102, the ECU 20 operates in a normal engine operating mode known in the art. When controlling the engine 12 during normal engine operation at step 102, the ECU 20 monitors or otherwise determines whether operation in a cylinder deactivation mode is commanded (step 104). In the illustrated embodiment, as long as cylinder deactivation mode operation is not determined in step 104, the ECU 20 continues to operate in the normal engine operating mode (step 102). During normal engine operation at step 102, the ECU 20 may control the fuel pump 14 in a conventional manner by, for example, operating the pumping unit 30 with the metering valve 33 in a closed state.

[0040] Figure 4 The ECU 20 is illustrated as determining whether to command or perform engine operation in a spark operation mode at step 104. In an embodiment, for example, at step 104, the ECU 20 may determine that a dynamic spark operation is being commanded or performed. In other embodiments, the ECU 20 may command or determine operation in other cylinder deactivation modes, such as fixed mode cylinder deactivation. The cylinder deactivation mode operation determined at step 104 may have been initiated, for example, by an operator of the engine system 8 using the operator control 35. In other cases, the ECU 20 may command operation in a cylinder deactivation mode based on its control algorithm (e.g., during normal engine operation) and monitored vehicle operating characteristics. As described above, when operating in a cylinder deactivation mode at step 104, the ECU 20 may implement any known or otherwise conventional control algorithm suitable for the operating mode and application. If it is determined at step 104 that the ECU 20 is not operating in a cylinder deactivation mode, the ECU may return to normal engine mode operation such as step 102.

[0041] After determining that the cylinder deactivation mode operation is being performed (step 104), the ECU 20 determines whether the fuel addition event associated with the operation is skipped, as shown in step 106. For example, when the ECU is operating in the dynamic spark mode, the ECU 20 can determine whether the fuel addition event is being skipped based on the firing of each cylinder. In other embodiments, the ECU 20 can determine that a group of fuel addition events are skipped during the fixed mode cylinder deactivation mode operation. If step 106 determines that no fuel addition event is skipped, the ECU 20 can return to normal engine mode operation, such as the operation of step 102.

[0042] pass Figure 4In the illustrated embodiment of the method 100, the ECU 20 is configured to perform a plurality of different deactivation mode accumulator pressure management operations. These accumulator pressure management operations include a first or normal optimized pressure operation 110 and a second or high optimized pressure operation 112. The ECU 20 determines which of the plurality of deactivation mode accumulator pressure management operations to perform based on other monitored or then activated control parameters. Figure 4 In the illustrated embodiment of the method 100, for example, at step 108, the ECU 20 determines whether an incremental engine load is requested during the same time period in which the fuel delivery event is skipped (step 106). Examples of incremental engine load requests that are monitored or otherwise determined are as described above and include throttle commands, gear shift operations, and / or requests to actuate an exhaust aftertreatment system.

[0043] If no incremental engine load request is pending or otherwise determined to be present when the fuel delivery event is skipped (step 108), the ECU 20 operates to perform a conventional optimized pressure operation 110. During the conventional optimized pressure operation 110, the ECU 20 compares the then current pressure within the accumulator 16 (e.g., monitored by the pressure sensor 36) to the above-mentioned MIN pressure level (e.g., minimum operating pressure level) (step 116). If it is determined in step 116 that the fuel pressure within the accumulator 16 is less than or equal to the MIN pressure level, the ECU 20 actuates one or more of the metering valves 33 to a closed state. Then, one or more pumping units 30 with the metering valves 33 in the closed state pump fuel to the accumulator 16, as shown in step 118, and thereby increase the pressure in the accumulator with the goal of maintaining the pressure at the MIN level. In conjunction with the operation of step 118, the ECU 20 can determine whether more than one pumping unit 30 is needed to achieve the desired fuel load in the accumulator 16. If it is determined that more than one pumping unit 30 is required, the ECU 20 may actuate the valves 33 of more than one pumping unit 30 to deliver fuel to the accumulator 16. If operating conditions do not require more than one pumping unit 30 to deliver pressurized fuel to the accumulator 16 to maintain the pressure at the MIN level, the ECU 20 may selectively determine between operating with one or more pumping units 30 based on criteria such as fuel economy, NVH, and pump durability.

[0044] If it is determined in step 116 that the fuel pressure within the accumulator 16 is greater than the MIN pressure level, the ECU 20 actuates one or more of the metering valves 33 to an open state (step 120). As shown in step 122, the operation of one or more pumping units 30 with the metering valves 33 in the open state will cause the fuel to be dumped, recirculated or diverted to a relatively low pressure system (such as the fuel source 31), or not pumped into the accumulator 16, thereby preventing the pressure in the accumulator from increasing in order to maintain the pressure at the MIN level. After executing step 118 or step 122, the ECU 20 may return to normal engine mode operation, such as step 102. The operation of the ECU 20 in the conventional optimized pressure operation 110 may reduce the possibility of an overpressure condition in the accumulator 16, and / or reduce the parasitic pumping work of the fuel pump 14 during the cylinder deactivation mode operation.

[0045] In an embodiment, if an incremental engine load request is pending or otherwise determined to be present when a fuel delivery event is skipped (step 108), the ECU 20 operates to perform a high optimized pressure operation 112. During the high optimized pressure operation 112, the ECU 20 compares the then current pressure within the accumulator 16 (e.g., provided by the pressure sensor 36) to the above-mentioned MAX pressure level (e.g., the maximum operating pressure level) (step 124). If it is determined at step 124 that the fuel pressure within the accumulator 16 is less than or equal to the MAX pressure level, the ECU 20 actuates one or more of the metering valves 33 to a closed state. Then, one or more pumping units 30 having closed-state metering valves 33 pump fuel to the accumulator 16, as shown at step 126, and thereby increase the pressure in the accumulator in order to maintain the pressure at the MAX level. During the high pressure optimized operation step 112, the ECU 20 may use an algorithm of the type described above in connection with the conventional optimized pressure operation 110 to determine the number of pumping units 30 to actuate.

[0046] If it is determined in step 124 that the fuel pressure within the accumulator 16 is greater than the MAX pressure level, the ECU 20 actuates one or more of the metering valves 33 to an open state (step 128). As shown in step 130, operation of one or more pumping units 30 with the metering valves 33 in the open state will cause the fuel to be dumped, recirculated, or diverted to a relatively low pressure system (such as the fuel source 31), or not pumped into the accumulator 16, thereby preventing the pressure in the accumulator from increasing in order to maintain the pressure at the MAX level. After executing step 126 or step 130, the ECU 20 may return to normal engine mode operation, such as step 102. When the system is operating in the cylinder deactivation mode, the operation of the ECU 20 under the high optimized pressure operation 112 may result in an increase in parasitic loads and / or support the ability of the engine 12 to provide the required power for effective and efficient operation of the engine system 8 and related systems.

[0047] The ability of the fuel addition system 10 to provide both normal optimized pressure operation 110 and high optimized pressure operation 112 during cylinder deactivation mode operation of the engine system 8 increases the overall effectiveness of the fuel addition system. Other embodiments of the fuel addition system 10 may operate using either or the other of the normal optimized pressure operation 110 or the high optimized pressure operation 112.

[0048] It should be understood that the above description is intended to be illustrative, rather than restrictive. By reading and understanding the above description, many other embodiments will be apparent to those skilled in the art. For example, it is conceivable that the features described in association with one embodiment may be optionally additionally or alternatively implemented to the features described in association with another embodiment. Therefore, the scope of the present invention should be determined with reference to the appended claims and the full scope of equivalents given by these claims.

Claims

1. A fuel addition system for an engine including a plurality of cylinders, the fuel addition system comprising: a plurality of fuel injectors for providing fuel to the plurality of cylinders; A common rail fuel accumulator connected to the plurality of fuel injectors, the common rail fuel accumulator being configured to provide fuel to the plurality of fuel injectors a high-pressure fuel pump, the high-pressure fuel pump comprising one or more pumping units and a corresponding number of one or more metering valves, each of the one or more pumping units comprising an inlet and an outlet, the outlet being connected to the common rail fuel accumulator, each of the one or more metering valves being electronically controllable to control fuel flow from the outlet of the corresponding one or more pumping units; a low-pressure pump connected between the high-pressure fuel pump and a fuel source, the low-pressure pump providing fuel from the fuel source to the inlet of the one or more pumping units; and an engine control unit configured to control fuel delivery from the common rail fuel accumulator to the plurality of fuel injectors and to control fuel delivery from the plurality of fuel injectors to the plurality of cylinders, the engine control unit further configured to determine a fuel pressure in the common rail fuel accumulator and control the one or more metering valves to manage the fuel pressure in the common rail fuel accumulator in a cylinder deactivation mode during which one or more fuel addition events to one or more of the plurality of cylinders are skipped, wherein the engine control unit is further configured to: determining that there is no incremental engine load request when skipping the one or more fuel addition events, in response to the pressure of the common rail fuel accumulator being less than a minimum operating pressure level, closing the one or more metering valves when skipping the one or more fuel addition events to provide fuel from the one or more pumping units to the common rail fuel accumulator, and in response to the pressure of the common rail fuel accumulator being greater than the minimum operating pressure level, opening the one or more metering valves while skipping the one or more fuel addition events to recirculate, dump or divert fuel from the one or more pumping units instead of supplying fuel to the common rail fuel accumulator; as well as In response to determining that the incremental engine load request is present while skipping one or more fuel addition events, in response to the pressure of the common rail fuel accumulator being less than a maximum operating pressure level but greater than a minimum operating pressure level, closing the one or more metering valves to provide fuel from the one or more pumping units to the common rail fuel accumulator while skipping one or more fuel addition events, and in response to the pressure of the common rail fuel accumulator being greater than the maximum operating pressure level, opening the one or more metering valves to recirculate, dump, or divert fuel from the one or more pumping units while skipping one or more fuel addition events without supplying the common rail fuel accumulator.

2. The fuel addition system according to claim 1, wherein the high-pressure fuel pump includes two pumping units and two metering valves associated with corresponding ones of the two pumping units, each of the two metering valves being electronically controllable by the engine control unit to control fuel flow into and out of the corresponding pumping unit to the common rail fuel accumulator.

3. The fuel addition system according to claim 2, wherein the engine control unit is configured to: determining whether one or both of the two pumping units are required to deliver pressurized fuel to the common rail fuel accumulator; In response to only one of the two pumping units being required, closing the metering valve of the one of the two pumping units to deliver pressurized fuel from the one or both pumping units to the common rail fuel accumulator while the metering valves of the other two pumping units remain open; and In response to two pumping units being needed, two metering valves for the two pumping units are closed to deliver pressurized fuel from the two pumping units. 4 . The fuel addition system of claim 1 , wherein the engine control unit is configured to determine that the engine is operating in the cylinder deactivation mode by determining that the engine is operating in the spark mode. 5 . The fuel addition system of claim 1 , wherein the engine control unit is configured to determine that the engine is operating in the cylinder deactivation mode by receiving a signal indicative of the cylinder deactivation mode operation. 6 . The fuel addition system of claim 5 , wherein the signal represents each skipped fuel addition event for each deactivated cylinder. 7 . The fuel addition system of claim 1 , wherein the engine control unit is configured to determine that the incremental engine load request is present in response to a throttle command while skipping the one or more fuel addition events. 8 . The fuel addition system of claim 1 , wherein the engine control unit is configured to determine that the incremental engine load request is present in response to a gear shift operation while skipping the one or more fuel addition events. 9 . The fuel addition system of claim 1 , wherein the engine control unit is configured to determine that the incremental engine load request exists in response to a request to actuate an exhaust aftertreatment system while skipping the one or more fueling events.

10. The fuel addition system according to claim 1, wherein: Each of the one or more pumping units of the high-pressure fuel pump includes a housing forming a pumping chamber fluidly coupled to the inlet and the outlet; Each of the one or more metering valves comprises: a base located in a pumping chamber of a corresponding pumping unit; solenoid; and an actuating rod actuable by the solenoid in response to a control signal from the engine control unit to move the seat in a reciprocating manner to open and close the metering valve; When the base is in the open position, the inlet is in fluid communication with the pumping chamber; and The inlet is fluidly sealed from the pumping chamber when the base is in the closed position.

11. The fuel addition system of claim 10, wherein the metering valve is normally open and the valve seat is spring biased into the open position.

12. The fuel addition system of claim 10, wherein each of the one or more pumping units comprises: An outlet valve is disposed within the housing between the pumping chamber and the outlet.

13. The fuel addition system of claim 12, wherein each of the one or more pumping units comprises: A plunger is driven by the rotational movement of the camshaft to compress the fuel in the pumping chamber, thereby forcing the fuel through the outlet valve to the common rail fuel accumulator when the valve seat is in the closed position.

14. The fuel addition system of claim 1 further comprising a pressure sensor coupled to the common rail fuel accumulator, the pressure sensor operable to provide a pressure measurement of the fuel in the common rail fuel accumulator to the engine control unit.

15. An engine control unit for a fuel addition system for an engine, the engine comprising a plurality of cylinders, the fuel addition system comprising a plurality of fuel injectors for providing fuel to the plurality of cylinders, a common rail fuel accumulator connected to the plurality of fuel injectors and configured to provide fuel to the plurality of fuel injectors, a high-pressure fuel pump, the high-pressure fuel pump comprising at least one pumping unit and at least one metering valve, the metering valve being electronically controllable to control fuel flow from an outlet and an inlet of the at least one pumping unit, wherein the engine control unit is configured to: controlling fuel delivery from the common rail fuel accumulator to the plurality of fuel injectors; controlling fuel delivery from the plurality of fuel injectors to the plurality of cylinders; determining a pressure of fuel in the common rail fuel accumulator; controlling the at least one metering valve to manage pressure of fuel in the common rail fuel accumulator in a cylinder deactivation mode during which one or more fuel addition events to one or more cylinders of the plurality of cylinders are skipped; determining that an incremental engine load request is absent when skipping the one or more fuel addition events, and in response, in response to a pressure in the common rail fuel accumulator being less than a minimum operating pressure level, closing the at least one metering valve when skipping the one or more fuel addition events to provide fuel from the at least one pumping unit to the common rail fuel accumulator, and in response to a pressure in the common rail fuel accumulator being greater than the minimum operating pressure level, opening the at least one metering valve while skipping the one or more fuel addition events to recirculate, dump, or divert fuel from the at least one pumping unit and not supply it to the common rail fuel accumulator; as well as In response to determining that an incremental engine load request is present when skipping the one or more fuel addition events, in response to the pressure of the common rail fuel accumulator being less than a maximum operating pressure level but greater than the minimum operating pressure level, closing at least one metering valve when skipping one or more fuel addition events to provide fuel from the at least one pumping unit to the common rail fuel accumulator, and in response to the pressure of the common rail fuel accumulator being greater than the maximum operating pressure level, opening at least one metering valve when skipping one or more fuel addition events to recirculate, dump, or divert fuel from the at least one pumping unit without supplying fuel to the common rail fuel accumulator. 16 . The engine control unit of claim 15 , wherein the engine control unit is configured to determine that the engine is operating in the cylinder deactivation mode by determining that the engine is operating in a spark mode. 17 . The engine control unit of claim 15 , wherein the engine control unit is configured to determine that the engine is operating in the cylinder deactivation mode by receiving a signal indicative of the cylinder deactivation mode operation.

18. The engine control unit of claim 17, wherein the signal represents each skipped fuel addition event for each deactivated cylinder.

19. The engine control unit according to claim 15, wherein: The engine control unit is configured to determine that the incremental engine load request exists in response to at least one of a throttle command, a gear shift operation, and a request to actuate an exhaust aftertreatment system during a period of skipping one or more fueling events for one or more of the plurality of cylinders.

20. The engine control unit of claim 15, wherein the engine control unit is configured to close one or both of a first metering valve of a first pumping unit and a second metering valve of a second pumping unit to provide fuel to the common rail fuel accumulator in response to: The common rail fuel accumulator pressure is less than the minimum operating pressure level when there is no incremental engine load request and one or more fueling events are skipped; and When there is an incremental engine load request and one or more fueling events are skipped, the pressure of the common rail fuel accumulator is less than the maximum operating pressure level.

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