Patent Publication Number: US-11022050-B2

Title: Automatic engine brake control systems and methods

Description:
RELATED APPLICATIONS 
     The present disclosure is related to and claims priority to U.S. Provisional Application No. 62/595,984, entitled “AUTOMATIC ENGINE BRAKE CONTROL SYSTEMS AND METHODS,” filed on Dec. 7, 2017, the entire disclosure of which is hereby expressly incorporated herein by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure generally relates to vehicle control systems for brake control devices, and more specifically to engine brake activation systems for performing automatic activation of a variable engine brake. 
     BACKGROUND OF THE DISCLOSURE 
     A conventional braking system and method for large vehicles, such as tractor trailer vehicles, is assisted by devices known as engine brakes or engine compression brakes. For example, an engine brake system utilizes an energy required to compress air into cylinders of an engine to brake the vehicle. A drag put on a drive line by the engine when placed in a compression braking mode can operate to slow the vehicle more rapidly, when used in conjunction with disc or drum brakes of the vehicle. 
     During over-speed conditions of the vehicle, an automated engine brake system can be activated to decelerate the vehicle. Conventional engine braking methods prevent excessive wear on friction brakes and reduce the risk of overheating the friction brakes by avoiding direct contacts between brake pads and corresponding rotors. Further, fuel injection engines typically cease to supply fuel into the engine while engine braking, known as deceleration fuel cut-off. However, such fuel cut-off does not protect the engine from the over-speed conditions at certain events, such as while traveling on a downhill grade path. Down gear-shifting performed during engine braking further increases an engine speed and can cause damage to other engine components. 
     Accordingly, it is desirable to develop a control system that improves operational limits of automatic engine brake systems and prevents engine damage cause by over-speed conditions. 
     SUMMARY OF THE DISCLOSURE 
     In one embodiment, the present disclosure provides a system for controlling operation of an engine brake system of an engine in a vehicle. The system includes a controller including an over-speed condition detection unit and an operation mode transition unit. The over-speed condition detection unit is configured to detect an over-speed condition based on a current engine speed and a fuel cut limit speed, the fuel cut limit speed being a predetermined engine speed at which fuel supplied to the engine is suspended. The operation mode transition unit is configured to control the operation of the engine brake system by transitioning the controller between a plurality of brake operation modes based on at least one transition parameter. 
     In one example, the system further includes a vehicle condition monitoring unit configured to monitor an operational state of the vehicle while the controller is activated. 
     In another example, the over-speed condition detection unit determines that the over-speed condition is satisfied when the current engine speed is greater than the fuel cut limit speed, and that the over-speed condition is not satisfied when the current engine speed is less than or equal to the fuel cut limit speed. In a variation, the over-speed condition detection unit is configured to detect the over-speed condition based on an activation state of the engine brake system. 
     In yet another example, the at least one transition parameter includes a first flag representing a first condition indicating whether the over-speed condition is satisfied. In a variation, the at least one transition parameter includes a second flag representing a second condition indicating whether the engine brake system is manually activated. In a further variation, the at least one transition parameter includes a third flag representing a third condition indicating whether the current engine speed is increasing in real time. In another variation, the at least one transition parameter includes a fourth flag indicating whether the current engine speed is decreasing in real time. In yet another variation, the at least one transition parameter includes a fifth flag indicating whether the engine brake system is currently active. In still another variation, the at least one transition parameter includes a sixth flag indicating whether a timer is expired. 
     In another embodiment, a system is provided for controlling operation of an engine brake system of an engine in a vehicle, using at least one processor. The system includes an initialization unit configured to generate an initialization signal based on a determination of whether the engine satisfies a minimum operation condition. Further, the system includes an over-speed condition detection unit configured to be initiated based on the initialization signal and to detect an over-speed condition based on a current engine speed and a fuel cut limit speed, the fuel cut limit speed being a predetermined engine speed at which fuel supplied to the engine is suspended, and an operation mode transition unit configured to control the operation of the engine brake system by transitioning the at least one processor between a plurality of brake operation modes based on a transition parameter. 
     In one example, the over-speed condition detection unit determines that the over-speed condition is satisfied when the current engine speed is greater than the fuel cut limit speed, and that the over-speed condition is not satisfied when the current engine speed is less than or equal to the fuel cut limit speed. 
     In another example, the plurality of brake operation modes includes at least two of: a normal engine operation mode, a hold mode, an engine brake activation mode, an engine brake deactivation mode, and a throttle operation mode. 
     In yet another example, the transition parameter includes at least one of: a first flag representing a first condition indicating whether the over-speed condition is satisfied; a second flag representing a second condition indicating whether the engine brake system is manually activated; a third flag representing a third condition indicating whether the current engine speed is increasing in real time; a fourth flag indicating whether the current engine speed is decreasing in real time; a fifth flag indicating whether the engine brake system is currently active; and a sixth flag indicating whether a timer is expired. 
     In yet another embodiment, a method of controlling operation of an engine brake system of an engine in a vehicle is provided. The method includes receiving, using at least one processor, a signal representative of a current engine speed from an engine speed sensor; detecting, using the at least one processor, an over-speed condition based on the current engine speed and a fuel cut limit speed, the fuel cut limit speed being a predetermined engine speed at which fuel supplied to the engine is suspended; and controlling, using the at least one processor, the operation of the engine brake system by transitioning the at least one processor between a plurality of brake operation modes based on a transition parameter. 
     In one example, the method further includes displaying data related to the operation of the engine brake system on a display device in real-time. 
     In another example, the method further includes determining that the over-speed condition is satisfied when the current engine speed is greater than the fuel cut limit speed, and that the over-speed condition is not satisfied when the current engine speed is less than or equal to the fuel cut limit speed. 
     In yet another example, the method further includes detecting the over-speed condition based on a current vehicle speed. 
     In still another example, the method further includes including, in the transition parameter, at least one of: a first flag representing a first condition indicating whether the over-speed condition is satisfied; a second flag representing a second condition indicating whether the engine brake system is manually activated; a third flag representing a third condition indicating whether the current engine speed is increasing in real time; a fourth flag indicating whether the current engine speed is decreasing in real time; a fifth flag indicating whether the engine brake system is currently active; and a sixth flag indicating whether a timer is expired. 
     In still yet another example, the method further includes detecting a change in a road grade on which the vehicle is traveling and pre-emptively activating the engine brake system in anticipation of the change in the road grade. While multiple embodiments are disclosed, still other embodiments of the present disclosure will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the present disclosure. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features of this disclosure and the manner of obtaining them will become more apparent and the disclosure itself will be better understood by reference to the following description of embodiments of the present disclosure taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a schematic illustration of an exemplary internal combustion engine system having an engine brake control unit in accordance with embodiments of the present disclosure; 
         FIG. 2  is a functional block diagram of the engine brake control unit of  FIG. 1  featuring related units and components in accordance with embodiments of the present disclosure; and 
         FIG. 3  is a flowchart illustrating one example of a method of performing an automatic engine brake control operation of a vehicle in accordance with embodiments of the present disclosure. 
     
    
    
     While the present disclosure is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the present disclosure to the particular embodiments described. On the contrary, the present disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims. 
     DETAILED DESCRIPTION OF EMBODIMENTS 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the present disclosure is practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present disclosure, and it is to be understood that other embodiments can be utilized and that structural changes can be made without departing from the scope of the present disclosure. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims and their equivalents. 
       FIG. 1  shows an exemplary internal combustion engine system  10  of a vehicle including an engine  12 , a fueling system  14  including a fuel mixer  16  to mix air with fuel and/or with a recirculated air/fuel mixture. In this example, engine  12  is a fuel engine operated by liquid fuel, such as gasoline, compressed natural gas (CNG), liquefied natural gas (LNG), or the like. Other suitable types of engines using gaseous fuels, such as liquefied hydrogen, propane, or other pressurized fuels, are also contemplated to suit different applications. In one embodiment, such as in a gasoline engine, the fuel is directly injected into cylinders  32  or port fuel injected into intake manifold  30 . In another embodiment, the air/fuel mixture is supplied to a fuel metering assembly or throttle  18 , or back to fuel mixer system  16  for mixing with fresh air and fuel in accordance with a signal provided by a controller  20 . 
     As used herein, “gas charge” refers to gases supplied to fuel metering assembly  18 . In this example, fueling system  14  includes a fuel control unit  22  configured to control an amount of fuel supplied from a fuel tank  24  to fuel mixer  16 . A fuel tank pressure sensor  26  monitors a pressure level inside fuel tank  24 , and reports a pressure reading to an engine control unit (ECU)  28 . Engine  12  includes intake manifold  30  receiving the gas charge from fuel metering assembly  18 , cylinders  32  to combust the gas charge, and exhaust manifold  34  receiving combustion gases from cylinders  32  and supplying the combusted gases to a charging subsystem as desired. In one embodiment, fuel metering assembly  18  includes a fuel shut-off valve, a pressure compensating by-pass valve, and the like. In this example, an intake throttle valve  36  is disposed at an entrance of intake manifold  30  to regulate an amount of fuel or air entering engine  12 . However, other configurations of intake throttle valve  36 , such as placing intake throttle valve  36  in a throttle body or a carburetor, are also contemplated to suit different applications, such as Port Fuel Injection (PFI) and Direct Injection (DI) fuel injectors. Variable open and closed positions of intake throttle valve  36  are controlled by ECU  28 . 
     Controller  20  includes ECU  28  operable to produce control signals on any one or more of signal paths  40  to control the operation of one or more corresponding suitably positioned engine components, such as fueling system  14 . One or more engine systems related the engine load, such as engine torque or horsepower, and other engine parameters, such as an engine speed or revolution per minute (RPM), are also controlled by ECU  28  for regulating operation of engine system  10 . ECU  28  is in communication with a controller area network (CAN) or other serial bus systems for communicating with various components and sensors on engine  12  and/or within the vehicle. 
     ECU  28  includes an engine brake control unit  42  configured to control operation of an engine brake system  44 . In one embodiment, engine brake system  44  includes a cylinder selector  46  and an engine brake relay  48 . For example, when engine brake relay  48  is energized cylinder selector  46  is activated for initiating compression braking of cylinders  32 . A variety of input signals are supplied to digital and analog inputs of ECU  28 , which inputs correspond to operating conditions of the vehicle. For example, a switch  50  is operatively coupled to a brake pedal  52  via linkage  54 , and ECU  28  is notified of the activation of brake pedal  52  via signal paths  40 . In embodiments, engine brake system  44  is activated automatically by engine brake control unit  42 , or manually by an activation device  56 , such as a button depressible by a user. Conversely, deactivation of engine brake system  44  is achieved automatically by engine brake control unit  42 , or manually by activation device  56 . Other suitable methods are also contemplated, such as depressing brake pedal  52  for deactivating engine brake system  44 . In another example, brake pedal  52  can be used to deactivate or activate the compression brake depending on vehicle operating conditions. 
       FIG. 2  shows an exemplary engine brake control unit  42  featuring its sub-units in accordance with embodiments of the present disclosure. In this example, engine brake control unit  42  includes an initialization unit  202 , an over-speed condition detection unit  204 , an operation mode transition unit  206 , a vehicle condition monitoring unit  208 , and a display unit  210 . Initialization unit  202  receives signals from sensors  212 , such as an engine speed sensor  213 , via hardware input/output (HWIO) devices  214 . In one example, HWIO devices  214  include an interface control unit  216  and hardware interfaces/drivers  218 . Interface control unit  216  provides an interface between the units  202 - 210 , and hardware interfaces/drivers  218 . Hardware interfaces/drivers  218  control operation of, for example, a camshaft phaser position sensor, a pressure sensor, engine speed sensor  213 , and other engine system components. Other engine system components include ignition coils, spark plugs, throttle valves, solenoids, etc. Hardware interface/drivers  218  also receive sensor signals, which are communicated to the control unit  42 . Memory  220  is operatively coupled to HWIO devices  214  to store and retrieve operational data and parameters. Memory  220  can be part of ECU  28  or separate from ECU  28 . 
     As an example only, interface control unit  216  is communicably coupled to controller  20 , and provides commands to controller  20  corresponding to a desired position of one or more valves, provides commands to controller  20  wherein at least one of the commands causes controller  20  to modify at least one of: an operational parameter of engine  12  and a mode of operation of engine  12 , and receives one or more parameter signals corresponding to an operational parameter of engine  12 . Although sub-units  202 - 210  are shown separately for illustration purposes, any combinations of sub-units are also contemplated to suit different applications. 
     In this example, sensors  212  include fuel tank pressure sensor  26  and engine speed sensor  213 , but other suitable sensors, such as an intake air temperature sensor or a vehicle speed sensor, are contemplated to suit different applications. Initialization unit  202  generates an initialization signal based on the signals from sensors  212  and determines whether to enable over-speed condition detection unit  204  by verifying that various initialization conditions are met. For example, the initialization conditions include ensuring that engine  12  satisfies a minimum operation condition, e.g., engine  12  is operable at a predetermined engine speed for a predetermined time period. When the initialization conditions are met, initialization unit  202  generates and transmits the initialization signal to over-speed condition detection unit  204 . 
     During engine operation, over-speed condition detection unit  204  is configured to detect an over-speed condition based on at least one of: a current engine speed of the vehicle and a fuel cut limit speed. In one example, the fuel cut limit speed can be set at 3800 RPM. For example, as the engine speed increases, engine brake control unit  42  can selectively stop fueling and activate engine brake system  44  at 3800 RPM. However, as the engine speed decreases, engine brake control unit  42  can turn off engine brake system  44  and fuel back on at 3600 RPM to provide a hysteresis margin from the 3800 RPM limit. 
     In another embodiment, over-speed condition detection unit  204  is configured to detect the over-speed condition based on a current vehicle speed. In one example, when the current engine speed is greater than the fuel cut limit speed, the over-speed condition is detected. The fuel cut limit speed refers to a predetermined engine speed at which the fuel supplied to engine  12  is suspended or cut off, e.g., by the fuel shut-off valve of fuel metering assembly  18 . In another example, the over-speed condition is detected based on an activation state of engine brake system  44 . For example, when engine brake system  44  is activated by depressing activation device  56 , the over-speed condition is detected. In one embodiment, over-speed condition detection unit  204  is configured to determine a current location of the vehicle and detect a change in a road grade on which the vehicle is traveling. For example, when a downhill grade is detected by over-speed condition detection unit  204 , engine brake system  44  can be automatically and pre-emptively activated by engine brake control unit  42  in anticipation of the upcoming downhill grade on the road. 
     Operation mode transition unit  206  is configured to perform a control operation on engine  12  by transitioning engine brake control unit  42  between a plurality of brake operation modes based on a transition parameter. Detailed descriptions of the transition parameter are provided below in paragraphs related to  FIG. 3 . In one embodiment, the plurality of brake operation modes include a normal engine operation mode that refers to a condition in which engine  12  is operated without activating engine brake system  44 . For example, while the over-speed condition is undetected, engine brake control unit  42  is in the normal engine operation mode. However, the plurality of brake operation modes includes other types of modes. For example, operation mode transition unit  206  transitions engine brake control unit  42  from the normal engine operation mode to a hold mode when the over-speed condition is detected. During the hold mode, engine brake system  44  remains deactivated to avoid actuating compressing brake system  44  prematurely. Detailed transitioning steps regarding the plurality of brake operation modes are described below in paragraphs related to  FIG. 3 . 
     Vehicle condition monitoring unit  208  is configured to monitor an operational state of the vehicle while engine brake control unit  42  is activated. In one embodiment, vehicle condition monitoring unit  208  monitors an engine speed of the vehicle for a predetermined time period using a timer  222 . For example, when the engine speed is less than the fuel cut limit speed before timer  222  expires, vehicle condition monitoring unit  208  instructs engine brake control unit  42  to transition to the normal engine operation mode because activation of engine brake system  44  is unnecessary. However, when the engine speed is greater than the fuel cut limit speed after timer  222  expires, vehicle condition monitoring unit  208  instructs engine brake control unit  42  to transition to one of the plurality of brake operation modes. 
     Display unit  210  is configured to display data related to the operation of engine  12 . In one example, display unit  210  receives and outputs data generated by engine brake control unit  42  for display, e.g., on a display device  224 . For example, the data related to the engine brake operation is presented on a screen or printed on a paper for viewing in real-time. For example, a smart display system is used to display textual or graphical illustrations representing one or more of the plurality of brake operation modes. In some embodiments, a user is notified by an alert or warning message, for example, using an audible or illuminating device available in the vehicle. Other suitable presentation methods are contemplated to suit the application. As described above, it is advantageous that engine brake control unit  42  provides control logic that selectively controls an engine speed, reduces a time period in which engine  12  is operated above the fuel cut limit speed, reduces engine components damage, and executes automatic engine protection features. 
       FIG. 3  shows an exemplary method  300  of performing automatic engine brake operation of a vehicle in accordance with embodiments of the present disclosure. It will be described with reference to  FIGS. 1 and 2 . However, any suitable structure can be employed. Although sub-blocks  302 - 316  are illustrated, other suitable sub-blocks can be employed to suit different applications. It should be understood that the blocks within the method can be modified and executed in a different order or sequence without altering the principles of the present disclosure. 
     In  FIG. 3 , a six-bit register stored in memory  220  is used as a transition parameter for indicating an operational state of the vehicle. In embodiments, vehicle condition monitoring unit  208  detects any change in the operational state of the vehicle that causes a modification of the transition parameter. In this example, a first bit of the transition parameter is a first flag representing a first condition (i.e., the over-speed condition) indicating whether a current engine speed (e.g., RPM) is greater than a fuel cut limit speed. A second bit of the transition parameter is a second flag representing a second condition indicating whether engine brake system  44  is manually activated, e.g., using activation device  56 . A third bit of the transition parameter is a third flag representing a third condition indicating whether a current engine speed is increasing in real time. For example, an engine speed rate is a positive number. 
     A fourth bit of the transition parameter is a fourth flag representing a fourth condition indicating whether a current engine speed is decreasing in real time. For example, the engine speed rate is a negative number. A fifth bit of the transition parameter is a fifth flag representing a fifth condition indicating whether engine brake system  44  is currently active. In one example, engine brake system  44  is activated after the hold mode when the current engine speed is greater than the fuel cut limit speed. In another example, engine brake system  44  is activated when activation device  56  is manually depressed bypassing the hold mode. A sixth bit of the transition parameter is a sixth flag representing a sixth condition indicating whether timer  222  is expired. Although the six-bit register having six flags are shown, a single transition parameter representative of one or more flags is also contemplated to suit different applications. 
     Each flag includes a first value of “1,” a second value of “0,” and a third value of “X,” wherein the first value indicates “YES,” the second value indicates “NO,” and the third value indicates “DON&#39;T CARE.” For example, when the sixth flag is “1,” timer  222  is expired, when the sixth flag is “0,” timer  222  is still running, and when the sixth flag is “X,” the value of sixth flag is irrelevant to operation of engine brake control unit  42 . 
     In  FIG. 3 , the method starts automatically at block  302  when engine  12  is started and remains operational during operation of engine  12 . In operation, at block  304 , initialization unit  202  receives signals from sensors  212 , such as engine speed sensor  213 , via HWIO devices  214 , and transmits the signals to over-speed condition detection unit  204  for determining whether an over-speed condition is satisfied. At block  304 , when the current engine speed is greater than the fuel cut limit speed, and engine brake system  44  is activated (e.g., transition parameter=“1XXX0X”), control proceeds to block  306 . In another example, when activation device  56  is depressed even though the current engine speed is less than or equal to the fuel cut limit speed or engine brake system  44  is inactivated (e.g., transition parameter=“01XX0X”), control proceeds to block  308 . 
     At block  306 , engine brake control unit  42  transitions to the hold mode. However, when the current engine speed is less than or equal to the fuel cut limit speed during the predetermined time period measured by timer  222 , and engine brake system  44  is not manually activated and is not currently activated (e.g., transition parameter=“00XX0X”), control proceeds to block  304  bypassing the hold mode. In one example, if the engine speed reduces below the fuel cut limit speed before timer  222  expires, engine  12  returns to the normal engine operation mode. In certain cases, however, such as during transient events (e.g., gearshift events on a steep downhill grade road), if timer  222  expires and the engine speed is not reduced, engine brake system  44  is automatically activated. When activation device  56  is depressed and engine brake system  44  is inactive (e.g., transition parameter=“X1XX0X”), control proceeds to block  308 . Also, when the over-speed condition is satisfied after timer  222  is expired, and engine brake system  44  is inactive (e.g., transition parameter=“1XXX01”), control proceeds to block  308 . At block  308 , engine brake control unit  42  transitions to an engine brake activation mode, and automatically activates engine brake system  44 . However, before the activation of engine brake system  44  is completed, when the over-speed condition is no longer satisfied and engine brake system  44  is not yet activated (e.g., transition parameter=“00XX1X”), control proceeds to block  310 . When the over-speed condition is still satisfied and engine brake system  44  is currently active (e.g., transition parameter=“1XXX1X”), then control proceeds to block  312 . Although the over-speed condition is not satisfied, when activation device  56  is depressed and engine brake system  44  is active (e.g., transition parameter=“01XX1X”), control proceeds to block  312 . 
     At block  310 , engine brake control unit  42  transitions to an engine brake deactivation mode, and automatically deactivates engine brake system  44 . However, during the brake deactivation mode, when the over-speed condition is satisfied again and engine brake system  44  is inactive (e.g., transition parameter=“1XXX0X”), control returns to block  306 . Also, even if the over-speed condition is not satisfied, when activation device  56  is depressed and engine brake system  44  is inactive (e.g., transition parameter=“01XX0X”), control returns to block  306 . When the over-speed condition is not satisfied and engine brake system  44  is not manually activated (e.g., transition parameter=“00XX0X”), control returns to block  304 . 
     At block  312 , engine brake control unit  42  transitions to a throttle operation mode, and maintains a current throttle position of intake throttle valve  36  for a predetermined time period. Engine brake control unit  42  is configured to control operation of throttle  18  and intake throttle valve  36  based on the transition parameter. In this example, throttle  18  and intake throttle valve  36  are used to control engine brake system  44 . In one example, during the throttle operation mode, when the over-speed condition is not satisfied, but engine brake system  44  is manually activated and the current engine speed is increasing (e.g., due to a downhill grade; and transition parameter=“01101X”), control proceeds to block  314 . Also, when the over-speed condition persists during the throttle operation mode, and the current engine speed is increasing and engine brake system  44  is currently active (e.g., transition parameter=“1X101X”), control proceeds to block  314 . 
     In another example, during the throttle operation mode, when the over-speed condition is not satisfied, but engine brake system  44  is manually activated and the current engine speed is decreasing (e.g., due to an uphill grade; and transition parameter=“01011X”), control proceeds to block  316 . Also, when the over-speed condition persists during the throttle operation mode, and the current engine speed is decreasing and engine brake system  44  is currently active (e.g., transition parameter=“1X011X”), control proceeds to block  316 . However, at block  312 , when the over-speed condition is not satisfied and engine brake system  44  is not manually activated (e.g., transition parameter=“00XX1X”), control proceeds to block  310 . 
     At block  314 , intake throttle valve  36  is variably opened to increase an intake air amount into engine  12  for generating a greater amount of braking torque. When the current engine speed is at a constant speed (e.g., neither increasing nor decreasing at a predetermined rate for a predetermined time period) and engine brake system  44  is active (e.g., transition parameter=“XX001X”), control proceeds from block  314  to block  312 . Conversely, at block  316 , intake throttle valve  36  is variably closed to decrease the intake air amount into engine  12  for generating a lesser amount of braking torque. In one example, while the vehicle is traveling downhill, coasting of the vehicle can be achieved by decreasing an intake fuel amount for facilitating fuel economy. In another example, during the engine brake activation mode, engine  12  may not be fueling, then the braking torque can be reduced by reducing an air flow through engine  12 . When the current engine speed is at the constant speed and engine brake system  44  is active (e.g., transition parameter=“XX001X”), control proceeds from block  316  to block  312 . 
     Embodiments of the present disclosure are described above by way of example only, with reference to the accompanying drawings. Further, the previous description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. As used herein, the term “unit” refers to, be part of, or include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor or microprocessor (shared, dedicated, or group) and/or memory (shared, dedicated, or group) that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. Thus, while this disclosure includes particular examples and arrangements of the units, the scope of the present system should not be so limited since other modifications will become apparent to the skilled practitioner. 
     Furthermore, while the above description describes hardware in the form of a processor executing code, hardware in the form of a state machine, or dedicated logic capable of producing the same effect, other structures are also contemplated. Although the sub-units  202 - 210  are illustrated as children units subordinate of the parent unit  42 , each sub-unit can be operated as a separate unit from ECU  28 , and other suitable combinations of sub-units are contemplated to suit different applications. Also, although the units  202 - 210  are illustratively depicted as separate units, the functions and capabilities of each unit can be implemented, combined, and used in conjunction with/into any unit or any combination of units to suit different applications. 
     In further embodiments, although engine  12  is illustrated as a gaseous fuel engine operated by liquid fuel, the present disclosure, such as engine brake control unit  42 , can be applied to any internal combustion engines using fossil fuels like natural gas or petroleum products such as gasoline, diesel fuel, fuel oil, or the like. Moreover, other renewable fuels, such as biodiesel for compression ignition engines and bioethanol or methanol for spark ignition engines can utilize the present disclosure. It is also contemplated that the present disclosure is similarly applicable to battery electric vehicles (BEVs) operated by an electric vehicle battery or traction battery. Other suitable types of electric vehicles, such as hybrid vehicles, can utilize the present disclosure. Further, any vehicle having a reciprocating engine can utilize the present disclosure. Any secondary or rechargeable battery operated vehicles can also implement the present disclosure for the engine brake operation. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. For example, it is contemplated that features described in association with one embodiment are optionally employed in addition or as an alternative to features described in associate with another embodiment. The scope of the present disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.