Patent Publication Number: US-8985079-B2

Title: Method and system for controlling a pneumatic starter

Description:
TECHNICAL FIELD 
     The present disclosure relates generally to a method and system for starting a machine, and more particularly, to a method and system for controlling a pneumatic starter of a machine. 
     BACKGROUND 
     Machines such as haul trucks, loaders, dozers, motor graders, and other types of heavy machinery have an engine for powering the machine. The engine may be a diesel engine, a gasoline engine, a natural gas engine, or any other type of engine known in the art. The engine may produce torque to power the machine, and likewise may require torque to start the engine. 
     The torque required to start the engine may be generated with a starter. For example, U.S. Pat. No. 4,494,499 (the &#39;499 patent) issued to Stein describes a diesel engine provided with a pneumatic starter that is powered with a pulsed delivery of pressurized gaseous fluid for a limited period of time. When powered, the pneumatic starter engages a pinion gear with a ring gear forming an outer peripheral part of a flywheel. The flywheel is fixed in driving relation to a crankshaft of the engine to provide the required torque to start the engine. The pneumatic starter of the &#39;499 patent may provide some help starting the engine, but it may be less than optimal. 
     The system of the present disclosure is directed toward solving one or more of the problems of the prior art. 
     SUMMARY 
     In one aspect, the present disclosure is directed to a system for controlling a starter for starting a power source. The system includes an air starter relay valve fluidly connected between an air tank and the starter. The air starter relay valve is configured to control an amount of air supplied to the starter from the air tank. The system also includes a control device connected to the air starter relay valve and configured to control the air starter relay valve. The system further includes a fuel valve interlock fluidly connected to a source of fuel via a fuel line. The fuel valve interlock is configured to open based on a pressure in the fuel line and configured to send a signal to the control device for controlling the air starter relay valve when the fuel valve interlock is opened. 
     In another aspect, the present disclosure is directed to a machine including a power source, an air tank, and a starter operatively connected to the power source and configured to receive air from the air tank to start the power source. The machine also includes an air starter relay valve fluidly connected between the air tank and the starter. The air starter relay valve is configured to control the supply of air to the starter from the air tank. The machine also includes a control device connected to the air starter relay valve and configured to control the air starter relay valve. The machine further includes a fuel pump configured to supply fuel to the power source and a fuel valve interlock fluidly connected to the fuel pump via a fuel line. The fuel valve interlock is configured to open based on a pressure in the fuel line, and configured to direct air from the air tank to the control device to control the air starter relay valve when the fuel valve interlock is opened. 
     In another aspect, the present disclosure is directed to a method for controlling a starter for starting a power source. The method includes directing a flow of air from an air tank to a fuel valve interlock and directing the flow of air from the fuel valve interlock to a control device based on a fuel pressure from a source of pressurized fuel. The method also includes directing a pilot signal from the control device to an air starter relay valve in response to receiving the flow of air from the fuel valve interlock. The method further includes opening the air starter relay valve in response to the pilot signal to supply air from the air tank to the starter via the air starter relay valve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a machine, according to an embodiment; and 
         FIG. 2  is a schematic illustration of a starting control system for the machine, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. 
       FIG. 1  illustrates an embodiment of a machine  10 . The machine  10  may have multiple systems and components that cooperate to accomplish a task. The machine  10  may embody a fixed or mobile machine that performs some type of operation associated with an industry such as mining, construction, farming, transportation, or another industry known in the art. For example, the machine  10  may be an earth moving machine such as an excavator, a wheel loader, a front shovel, a bulldozer, a backhoe, a telehandler, a motor grader, a dump truck, or any other earth moving machine. 
     The machine  10  may have a power system  12 , and the power system  12  may include an engine  14  having a flywheel  16 . The engine  14  may be, for example, a diesel engine, a gasoline engine, a gaseous fuel-powered engine, or any other type of combustion engine known in the art. The flywheel  16  may be connected to the engine  14 . For example, the flywheel  16  may be connected to a crankshaft  18  of the engine  14 , or in any other manner known in the art. The flywheel  16  may be any type of device for storing and releasing rotational energy to dampen transient loads placed on or exerted by the engine  14 . For example, the flywheel  16  may be a fixed inertia flywheel, a variable inertia flywheel, an electric flywheel, or any other flywheel known in the art. In addition, the flywheel  16  may include multiple rotating masses. It is also contemplated that the flywheel  16  may be absent from the engine  14  and that another device for storing and releasing rotational inertia may be provided. 
     The power system  12  may also include a starter  20  that may be connected to the engine  14  by engaging a pinion gear  22  with external gear teeth (not shown) of the flywheel  16 . The starter  20  may also be connected to engine  14  in other ways. For example, the starter  20  may engage the pinion gear  22  with a gear (not shown) fixed to the crankshaft  18 , a ring gear (not shown) on the flywheel  16 , or in any other way known in the art. The starter  20  may also directly engage the device for storing and releasing rotational inertia in the system where the flywheel  16  is absent. The starter  20  may be any device for applying torque sufficient to rotate the crankshaft  18  causing one or more pistons (not shown) to reciprocate within one or more cylinders (not shown) of the engine  14 , such as a pneumatic starter. 
     The machine  10  may also include an operator station or cab  30  situated for manual control of the power system  12  and other systems and components. The operator cab  30  may include devices that receive input from an operator indicative of desired machine maneuvering, e.g., starting the engine  14 . Specifically, the operator cab  30  may include one or more operator interface devices (e.g., a joystick, a steering wheel, pedals, buttons, etc.) that are located proximate an operator seat. The operator interface devices in the operator cab  30  may include one or more start buttons  32  ( FIG. 2 ) to initiate starting of the engine  14  as will be described below. In the embodiment shown, the machine  10  includes two start buttons, e.g., for a two-handed start by the operator. Alternatively, the machine  10  may include a single start button, more than two start buttons, or other types of input devices to indicate a start. 
     The machine  10  may include a pneumatic starting control system  40  for controlling the start of the engine  14 . For example, the starting control system  40  may be in fluid communication with components of the machine  10  (e.g., the engine  14 ) and the starter  20  to supply compressed air to the starter  20  to start the engine  14 . For example, the compressed air may be supplied to spin a turbine (not shown) that may rotate the pinion gear  22  ( FIG. 1 ) that is engaged with the flywheel  16 . The starting control system  40  may control when to initiate the start of the engine  14  (e.g., when to supply the compressed air to the starter  20 ), and may delay or prevent the start of the engine  14 . 
     As illustrated in  FIG. 2 , the starting control system  40  may be provided for a pneumatic starting arrangement and may include a pneumatic circuit or system having a plurality of components that cooperate to selectively direct pressurized air or other fluid to the starter  20  to initiate starting of the engine  14 . For example, in the embodiment shown in  FIG. 2 , the starting control system  40  may include an air tank  42  and an air starter relay valve  44 . 
     The air tank  42  may include a source of compressed air, such as, for example, an air reservoir. After starting the engine  14 , the engine  14  may drive a compressor (not shown) to recharge the air tank  42 . Although only a single tank  42  is shown, it is also contemplated that the starting control system  40  may be in fluid communication with multiple, separate air tanks. 
     The air starter relay valve  44  may be actuated into open and close positions. In the open position, compressed air is supplied from the air tank  42  to the starter  20 . The air starter relay valve  44  may be actuated in response to a command signal or pilot signal (e.g., an air signal) from a control device. In the embodiment of  FIG. 2 , the control device includes an interval delay valve  50  or other control valve. Alternatively, the pilot signal may be an electrical signal or other fluid signal. The interval delay valve  50  may be configured to send the pilot signal to the air starter relay valve  44  to actuate the air starter relay valve  44  to allow air to be supplied from the air tank  42  to the starter  20  to start the engine  14 . 
     The interval delay valve  50  may control whether to deliver the pilot signal to the air starter relay valve based on one or more signals (e.g., an air signal) received from one or more other valves in the starting control system  40 , including a park brake interlock  60 , a shifter or transmission interlock  70 , a fuel valve interlock  80 , and one or more start valves  90  connected to the start button(s)  32  described above. For example, in the embodiment of  FIG. 2 , the interval delay valve  50  may receive a flow of air or air signal from the air tank  42  when the two start buttons  32 , the park brake interlock  60 , the transmission interlock  70 , and the fuel valve interlock  80  are in their open positions. Although the park brake interlock  60 , the transmission interlock  70 , and the start valves  90  are shown in  FIG. 2  as including push buttons, it is understood that push buttons may be omitted. The park brake interlock  60 , the transmission interlock  70 , and the start valves  90  may be actuated in response to inputs from other types of components. 
     The park brake interlock  60  may be actuated into an open position so that the park brake interlock  60  may allow air to be fluidly communicated from the air tank  42  to the transmission interlock  70 . The park brake interlock  60  is configured to be actuated when a park brake (not shown) of the machine  10  is set, e.g., when a mechanical detent (not shown) of a linkage of the park brake contacts the park brake interlock  60 . 
     The transmission interlock  70  may also be actuated into an open position so that the transmission interlock  70  may allow air to be fluidly communicated from the air tank  42  (via the park brake interlock  60  when it is also in the open position) to the fuel valve interlock  80 . The transmission interlock  70  is configured to be actuated when a transmission (not shown) of the machine  10  is in neutral position, e.g., when a mechanical detent (not shown) of a linkage of the transmission contacts the transmission interlock  70 . 
     The fuel valve interlock  80  may also be actuated into an open position so that the fuel valve interlock  80  may allow air to be fluidly communicated from the air tank  42  (via the park brake interlock  60  and the transmission interlock  70  when they are both also in open positions) to the start valves  90 . The fuel valve interlock  80  is configured to be actuated when a fuel pressure is above a threshold. In the embodiment of  FIG. 2 , the fuel valve interlock  80  is configured to be actuated when a fuel pressure received via a fuel line  82  from a fuel pump  84  or other source of pressurized fuel is above a threshold. The threshold may depend on the application, e.g., the type and size of the engine  14 . For example, the fuel pump  84  may be a hand pump that may draw fuel from a fuel tank (not shown) in order to supply pressurized fuel to the engine  14  for starting. 
     The start valves  90  may also be actuated into open positions so that the start valves  90  may allow air to be fluidly communicated from the air tank  42  (via the park brake interlock  60 , the transmission interlock  70 , and the fuel valve interlock  80  when they are all in open positions) to the interval delay valve  50 . The start valves  90  are configured to be actuated when the operator has pressed the start buttons  32 , as described above, to indicate a desire to start the engine  14 . 
     The interval delay valve  50  is configured to send the pilot signal to the air starter relay valve  44  as described above when the flow of air is fluidly communicated from the start valves  90  to the interval delay valve  50 . Alternatively, the interval delay valve  50  may delay the delivery of the pilot signal to the air starter relay valve  44  to ensure that a period of time separates consecutive openings of the air starter relay valve  44 . For example, the interval delay valve  50  may be configured to determine when the start button(s)  32  were pressed (or when the start valve(s)  90  were opened) previous to the most recent pressing of the start button(s)  32  (or the most recent opening of the start valve(s)  90 ). If the time difference is less than a certain time period, e.g., approximately one second up to approximately thirty seconds (e.g., approximately six seconds), then the interval delay valve  50  may delay sending the pilot signal to the air starter relay valve  44  until the time period has been completed, or after a different time delay. In addition, the interval delay valve  50  may also be configured to provide other limits to the actuation of the air starter relay valve  44 , e.g., by limiting the amount of time that the air starter relay valve  44  is opened. 
     INDUSTRIAL APPLICABILITY 
     The disclosed control system and method may have particular applicability with machines having a pneumatic starting arrangement. The disclosed control system and method may control when to start the engine  14  to ensure that adequate fuel pressure and air pressure are provided during the start. Operation of the machine  10  will now be described. 
     An operator located within the operator cab  30  may command the start of the engine  14  by way of an interface device, e.g., by pressing the start buttons  32  simultaneously with the operator&#39;s two hands. Signals generated by the start buttons  32  may be provided to actuate the start valves  90  to move to open positions. If the transmission is in neutral, the park brake is set, and the fuel pressure from the fuel pump  84  is above the threshold, then the park brake interlock  60 , the transmission interlock  70 , and the fuel valve interlock  80  may also be in open positions. When the park brake interlock  60 , the transmission interlock  70 , the fuel valve interlock  80 , and the start valves  90  are all in open positions, a flow of air may be directed from the air tank  42  to the interval delay valve  50  to serve as an air signal indicating an engine start command. The park brake interlock  60  and the transmission interlock  70  may ensure that the engine  14  does not start until the park brake is set and the transmission is in neutral. 
     The air tank  42  includes a limited amount of compressed air, which limits the number of possible start attempts for the engine  14 . The starting control system  40  prevents the waste of compressed air from the air tank  42  by providing the fuel valve interlock  80  that allows air to be directed to the interval delay valve  50  only if the fuel pressure is above the threshold that corresponds to a fuel pressure that is determined to be sufficient to permit the engine  14  to start. The fuel valve interlock  80  may ensure that there is sufficient fuel pressure to start the engine  14  before allowing air to be supplied from the air tank  42  to the starter  20  to start the engine  14  and therefore may help to prevent wasting air from the air tank  42  on unsuccessful start attempts. Since there may be no limit to the amount of time or number of times that the start buttons  32  may be pressed, the fuel valve interlock  80  may prevent air from being depleted from the air tank  42  before being able to provide the required torque to start the engine  14 . 
     When the interval delay valve  50  receives the flow of air from the air tank  42 , the interval delay valve  50  may delay sending the pilot signal to the air starter relay valve  44 . For example, the interval delay valve  50  may ensure that a time delay of at least approximately one second to thirty seconds separates each start attempt (e.g., between each time the air starter relay valve  44  is opened). Thus, the interval delay valve  50  may also serve to prevent the operator from depleting air unnecessarily from being released from the air tank  42  to the starter  18  and may ensure that the engine  14  may have enough time to coast to stop after the previous start attempt. As a result, damage to the starter  20 , the pinion gear  22 , and/or the flywheel  16  may be reduced by helping to avoid engaging the pinion gear  22  with the flywheel  16  while the crankshaft  18  is still rotating. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed method and system. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed method and system. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.