Patent Publication Number: US-2018030900-A1

Title: Air Turbine Starter with Integrated Motor for Main Engine Cooling

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to an engine system with an air turbine starter and, more particularly, relates to an air turbine starter with an integrated motor for main engine cooling. 
     BACKGROUND 
     An engine, such as a gas turbine engine, will generate heat due to combustion, friction, and/or other causes. This heat may be transferred through the various parts of the engine during operation. In some instances (e.g., after and/or during shutdown of the engine), a heat gradient may develop between different areas of the engine. For example, one or more rotating parts of the engine may cool unevenly after engine shutdown. Ultimately, this may decrease the efficiency of the engine and/or cause other undesireable effects. 
     Accordingly, it is desirable to provide a device that allows the engine to cool substantially evenly and to avoid substantial temperature gradients. It is also desirable that the device be lightweight and compact. Other desirable features and characteristics of the present disclosure will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background. 
     BRIEF SUMMARY 
     In one embodiment, an air turbine starter for a main engine includes a support structure and an airflow passage extending at least partially through the support structure. The air turbine starter also includes a turbine that is supported by the support structure for rotation relative to the support structure. The turbine is configured to be driven in rotation due to air flowing through the airflow passage. The air turbine starter additionally includes a gear train that is operably coupled to the turbine and configured for receiving turbine torque input from the turbine. The plurality of gears includes an integrated input gear. The air turbine starter further includes an output member that is supported by the support structure for rotation relative to the support structure. The output member is operably coupled to the gear train and a main engine input member. The output member is configured to transfer torque from the gear train to the main engine input member. Additionally, the air turbine starter includes a motor system that is supported by the support structure. The motor system includes a motor and a motor output gear. The motor output gear is configured to engage the integrated input gear for selectively delivering motor torque from the motor to the integrated input gear such that the motor torque is transferred to the output member and delivered to the main engine input member. 
     In another embodiment, an engine system includes an engine and an air turbine starter that includes a gear train that is operably coupled to the engine. The gear train includes an input gear. The air turbine starter is configured to receive input air, and the input gear is configured to rotate as a result of the flow of the input air to move at least one part of the engine. The engine system further includes a motor and a motor output gear that is rotated by the motor. The motor and motor output gear are configured to selectively drive and rotate the input gear of the gear train to move the at least one part of the engine. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein: 
         FIG. 1  is an environmental view of an engine system that includes a main engine and an air turbine starter according to exemplary embodiments of the present disclosure; 
         FIG. 2  is a cross-sectional view of the air turbine starter taken along the line  2 - 2  of  FIG. 1 , wherein the air turbine starter includes an integrated motor according to exemplary embodiments of the present disclosure; and 
         FIG. 3  is a cross-sectional view of the integrated motor according to additional embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the present disclosure or the application and uses of the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. In addition, those skilled in the art will appreciate that embodiments of the present disclosure may be practiced in conjunction with any type of device that would benefit from an air turbine starter with an integrated motor for cooling of a main engine. It will also be appreciated that the air turbine starter and the integrated motor described herein is merely exemplary and configured according to the present disclosure. Moreover, the integrated motor may be used with an air turbine starter for a gas turbine engine that is onboard a mobile platform or vehicle (e.g., an aircraft, a bus, motorcycle, train, motor vehicle, marine vessel, rotorcraft and the like). The various teachings of the present disclosure may also be used with an air turbine starter and/or a gas turbine engine associated with a stationary platform. Further, it should be noted that many alternative or additional functional relationships or physical connections may be present in an embodiment of the present disclosure. In addition, while the figures shown herein depict examples with certain arrangements of elements, additional intervening elements, devices, features, or components may be present in an actual embodiment. It should also be understood that the drawings are merely illustrative and may not be drawn to scale unless otherwise noted. 
     As used herein, the term module refers to any hardware, software, firmware, electronic control component, processing logic, and/or processor device, individually or in any combination, including without limitation: application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality. 
     Embodiments of the present disclosure may be described herein in terms of functional and/or logical block components and various processing steps. It should be appreciated that such block components may be realized by any number of hardware, software, and/or firmware components configured to perform the specified functions. For example, an embodiment of the present disclosure may employ various integrated circuit components, e.g., memory elements, digital signal processing elements, logic elements, look-up tables, or the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices. In addition, those skilled in the art will appreciate that embodiments of the present disclosure may be practiced in conjunction with any number of systems, and that the ATS vehicle system described herein is merely one exemplary embodiment of the present disclosure 
     For the sake of brevity, conventional techniques related to signal processing, data transmission, signaling, control, and other functional aspects of the systems (and the individual operating components of the systems) may not be described in detail herein. 
     Referring now specifically to the drawings,  FIG. 1  illustrates an engine system  10  according to exemplary embodiments. The engine system  10  may be mounted to a vehicle  12 , such as an aircraft, in some embodiments. 
     In the illustrated embodiment, the engine system  10  generally includes a main engine  14  and an air turbine starter  110  (ATS). The main engine  14  may be a gas turbine engine in some embodiments. The ATS  110  is used to move one or more parts of the main engine  14 , for example, when starting the main engine  14 . More specifically, operation of the ATS  110  causes movement of one or more parts of the main engine  14  before combustion occurs within the main engine  14 . In some embodiments, the ATS  110  may continue to provide input to the main engine  14  after initial combustion until a shut off signal is sent to the ATS  110 . Then, the main engine  14  drives movement of its parts, without input from the ATS  110 . These and other operations of the engine system  10  will be discussed in detail below. 
     In some embodiments, the main engine  14  includes a support structure  16  that is connected to the vehicle  12  and that supports a plurality of moveable parts  18  therein. The support structure  16  may include various parts that remain static relative to the vehicle  12 , whereas the moveable parts  18  move relative to the support structure  16  and the vehicle  12 . The moveable parts  18  may include one or more rotors, blades, shafts, etc. The moveable parts  18  also include a main engine input member  20  (shown in phantom in  FIG. 1 ). The main engine input member  20  may be an elongate shaft that is rotatable and may be supported by a starter pad on the gearbox of the main engine  14 . The main engine input member  20  connects to (i.e., engages, couples with, etc.) an output member of the ATS  110  as will be explained in detail below. Accordingly, torque output from the ATS  110  may be transferred to the main engine input member  20 . 
     During operation of the ATS  110  (e.g., during startup of the main engine  14 ), air flows via an input tube  111  into the ATS  110 . As will be discussed in detail, this air input rotatably drives one or more parts inside the ATS  110 . Resultant torque from the ATS  110  transfers to the main engine input member  20 , and the torque transfers from the main engine input member  20  to the other moveable parts  18  of the main engine  14  (e.g., the rotors, blades, and shafts of the main engine  14 ). The ATS  110  increases the angular velocity of the moveable parts  18  from a stopped position to a so-called “combustion speed” or “light-off speed”. At this point, combustion occurs in the main engine  14 , thereby further increasing the angular velocity of the moveable parts  18  to a so-called “operational speed” or “cutout speed”. Airflow to the ATS  110  through the ATS input tube  111  ceases the main engine  14  reaches operational or cutout speed, and the main engine  14  operates independently of the ATS  110  until shutdown. Then, at shutdown of the main engine  14 , the moveable parts  18  of the main engine  14  slow down and eventually stop. 
     As will be discussed, the ATS  110  includes components that may be used during shutdown (or any time before the next start of the main engine  14 ) to keep the moveable parts  18  of the main engine  14  moving. This can help the main engine  14  to cool more evenly as compared to main engines of the prior art. 
     Specifically, in some embodiments, the ATS  110  includes an integrated motor system  115  ( FIG. 2 ) used for cooling of the main engine  14 . As will be discussed, torque output from the integrated motor system  115  can transfer through parts of the ATS  110  to the main engine input member  20  to keep the moveable parts  18  of the main engine  14  moving. In some embodiments, the integrated motor system  115  may take advantage of the existing torque path of the ATS  110  (and, in some embodiments, the gear reduction and/or clutch of the ATS  110 ). Accordingly, the integrated motor system  115  can be lightweight, compact, and inexpensive to incorporate into the engine system  10 . 
     Referring now to  FIG. 2 , the ATS  110  will be discussed in detail according to exemplary embodiments of the present disclosure. As shown, the ATS  110  may include a support structure  117 , which attaches to the main engine  14  and/or the vehicle  12 . The support structure  117  may include a first housing assembly  112  and a second housing assembly  113 . The first housing assembly  112  defines a flow path  114  extending from an inlet  116  to an outlet  118  through the support structure  117 . The ATS input tube  111  ( FIG. 1 ) may be fluidly connected to the inlet  116  to supply air thereto. The second housing assembly  113  may include a mounting flange  119  for mounting the ATS  110  to the support structure  16  of the main engine  14  ( FIG. 1 ). 
     Within the ATS  110 , the housing assemblies  112 ,  113  support a turbine section  120 , a gear train  140 , and an overrunning clutch  160 . The first housing assembly  112  substantially houses the turbine section  120  and defines the flow path  114 . The second housing assembly  113  substantially houses the gear train  140  and the overrunning clutch  160 . Specific details of the turbine section  120 , gear train  140 , and overrunning clutch  160  are explained below. 
     The turbine section  120  may include a turbine  122  having a wheel  123  and a rotatable shaft  124  extending therefrom. The turbine  122  is supported (i.e., journaled) by bearings  126   a ,  126   b  for rotation relative to a turbine exhaust housing  127 , which is part of the first housing assembly  112 . A plurality of turbine blades  128  are circumferentially mounted to the wheel  123  and are positioned within the flow path  114 . Upstream of the blades  128  are a plurality of nozzles  129  mounted to the inlet  116  which provide the proper flow angle to the air flow before it flows to the turbine blades  128 . In operation, pressurized air entering through inlet  116  is properly aligned by the nozzles  129  and is then expanded across the blades  128  before exiting through outlet  118 . The blades  128  convert the pressure energy of the air into rotary motion, causing the wheel  123  and the shaft  124  of the turbine  122  to rotate at the same speed as the blades  128 . 
     In some embodiments, the gear train  140  is a compound planetary gear train  140  that is operably coupled to the turbine  122  and configured for receiving turbine torque input from the turbine  122 . More specifically, the gear train  140  includes a sun gear  125 , which is fixed to the shaft  124  for rotation therewith. The gear train  140  also includes a plurality of planetary gears  144 , each supported by a respective shaft  142 . The planetary gears  144  may be enmeshed with the sun gear  125 . The gear train  140  may also include a ring gear  148 , which surrounds and supports the planetary gears  144 . A first inner diameter part  149  of the ring gear  148  enmeshes with the planetary gears  144 . The gear train  140  may also include a hub gear  162 , which is enmeshed with a second inner diameter part  146  of the ring gear  148 . The hub gear  162  may be considered an input side of the overrunning clutch  160 . 
     In operation, torque may transfer through the gear train  140  from the shaft  124  to the clutch  160 . Specifically, the sun gear  125  rotates with the shaft  124 , and torque travels from the sun gear  125 , through the planetary gears  144 , through the ring gear  148 , and to the hub gear  162 . The gear train  140  also provides a predetermined gear ratio or gear reduction. Accordingly, the gear train  140  converts the high speed, low torque output of the turbine section  120  into low speed, high torque input for the clutch  160 . 
     In some embodiments, the clutch  160  is a sprag type clutch, although other clutch mechanisms may be used. The clutch  160  includes the hub gear  162  on its input side and a clutch output member  170  on its output side. The hub gear  162  includes a hollow cylindrical hub portion  163 , which is supported on bearings  164   a ,  164   b . The clutch output member  170  is supported for rotation relative to the support structure  117  and may include a shaft decoupler assembly  190  splined into the inner race of the bearings  164   a ,  164   b . The clutch output member  170  is coupled to the main engine input member  20 . In operation, when the clutch  160  is in its clutched position, the clutch  160  delivers torque from the hub gear  162  to the main engine input member  20 , for example, during startup of the main engine  14 . The clutch  160  also has an unclutched position, preventing torque from transferring back from the main engine input member  20  to the hub gear  162 . This can occur, for example, once combustion begins in the main engine  14  and the main engine input member  20  begins to rotate faster than the hub gear  162 . 
     The ATS  110  also includes the integrated motor system  115 . As will be discussed, the integrated motor system  115  selectively delivers torque to the main engine input member  20 . In some embodiments, the integrated motor system  115  is used after shutdown of the main engine  14 , for example, to provide substantially even cooling of the main engine  14 . 
     The integrated motor system  115  includes a motor  130  with a motor output shaft  132 . In some embodiments, the motor  130  may be an electric motor, such as a two-kilowatt motor able to output approximately 10,000 RPMs. However, it will be appreciated that the motor  130  can be of other types without departing from the scope of the present disclosure. 
     The motor  130  may be received in a motor cavity  138 , which is defined within the second housing assembly  113  of the ATS  110 . The motor output shaft  132  may extend away from the motor  130  and out of the motor cavity  138  such that the motor output shaft  132  extends toward the gear train  140  of the ATS  110 . 
     The motor system  115  also includes a motor output gear  134 , which is driven in rotation by the motor output shaft  132 . In some embodiments, the motor output gear  134  is a spur gear. However, it will be appreciated that the motor output gear  134  may be a helical gear, a bevel gear, or other type of gear without departing from the scope of the present disclosure. The motor output gear  134  engages and meshes with the gear train  140  of the ATS  110  as will be discussed in greater detail below. 
     Additionally, the integrated motor system  115  may include a motor gear train  136 , which is illustrated schematically in  FIG. 2 . The motor gear train  136  of the integrated motor system  115  may include a plurality of gears that are operably connected in series between the motor output shaft  132  and the motor output gear  134 . In some embodiments, the motor gear train  136  may be configured such that the motor output shaft  132  and the motor output gear  134  have substantially parallel axes of rotation. In operation, the motor gear train  136  may provide a predetermined gear reduction between the motor output shaft  132  and the motor output gear  134 . As such, the motor gear train  136  may convert the relatively high speed, low torque output of the motor output shaft  132  to the relatively low speed, high torque rotation of the motor output gear  134 . It will be appreciated that the motor gear train  136  is optional and that, in other embodiments, the motor  130  may directly rotate the motor output gear  134 . Specifically, the motor output gear  134  may be attached to the motor output shaft  132  so that the motor output gear  134  and the motor output shaft  132  rotate at the same speed. 
     The motor output gear  134  may engage the gear train  140  of the ATS  110  such that torque output from the motor  130  is transferred through at least part of the gear train  140  to the main engine input member  20 . In some embodiments, the motor output gear  134  may be engaged to a portion of the ring gear  148  of the gear train  140 . Specifically, in the embodiment of  FIG. 2 , an outer diameter part  152  of the ring gear  148  includes outwardly projecting gear teeth that mesh with opposing gear teeth of the motor output gear  134 . Thus, the outer diameter part  152  of the ring gear  148  may be referred to as an “integrated input gear  150 ” that receives torque input from the integrated motor system  115 . It will be appreciated, however, that another part of the gear train  140  of the ATS  110  may serve as the integrated input gear  150  for receiving torque input from the integrated motor system  115  without departing from the scope of the present disclosure. The ring gear  148  may also be referred to as a “combination gear” in that it both: (1) transfers torque input from the turbine  122  to the main engine input member  20  in some scenarios; and (2) transfers torque input from the integrated motor system  115  to the main engine input member  20  in other scenarios. 
     The integrated motor system  115  may additionally include a motor clutch  154  in some embodiments. The motor clutch  154  may be an overrunning clutch or a sprag clutch in some embodiments. The motor clutch  154  may be supported on the motor output shaft  132  in some embodiments. In additional embodiments, the motor clutch  154  may be supported on the same shaft as the motor output gear  134 . The motor clutch  154  is configured to provide one-way torque transfer from the motor  130  to the ring gear  148 . In other words, the motor clutch  154  can have a clutched position, in which motor torque from the motor  130  causes the motor output gear  134  to rotate the ring gear  148 . However, if the ring gear  148  is rotating faster than the motor output gear  134 , the motor clutch  154  can move to an unclutched position to prevent torque from the ring gear  148  from travelling back toward the motor  130 . 
     Moreover, the integrated motor system  115  may include a frangible member  156 . The frangible member  156  may be referred to as a “shear section.” The frangible member  156  may be incorporated within the motor output shaft  132  in some embodiments. The frangible member  156  may have a predetermined fracture strength. In some embodiments, for example, the frangible member  156  may be a thinned area of the motor output shaft  132  that has a lower fracture strength compared to other areas along the torque path of the motor system  115 . If torque or other force on the frangible member  156  is below the predetermined fracture strength, then the frangible member  156  remains rigid (i.e., the frangible member  156  remains in a first configuration), allowing for torque transfer through the motor system  115 . However, if the force on the frangible member  156  exceeds the predetermined fracture strength, then the frangible member  156  fractures (i.e., the frangible member  156  moves to a second, fractured configuration), preventing torque transfer through the motor system  115 . The predetermined fracture strength can be significantly above (e.g., an order of magnitude above) the forces normally associated with torque transfer between the motor  130  and the gear train  140  of the ATS  110 . Thus, the frangible member  156  may remain rigid during normal operations, and the frangible member  156  may fracture, for example, if the motor  130  jams or otherwise fails. Accordingly, the frangible member  156  may fracture to protect other parts of the motor system  115 . 
     Additionally, in some embodiments, at least part of the integrated motor system  115  may be lubricated by the same lubricant  139  as the gear train  140  of the ATS  110 . (The lubricant  139  is illustrated schematically in  FIG. 2 .) In some embodiments, the motor output gear  134 , the motor gear train  136 , and the motor clutch  154  are disposed in a cavity  192  within the second housing assembly  113 , and the gear train  140  of the ATS  110  is housed within the same cavity  192 . Accordingly, the lubricant  139  may commonly lubricate the motor output gear  134 , the motor gear train  136 , the motor clutch  154 , as well as the ring gear  148  and other parts of the gear train  140 . Furthermore, the integrated motor system  115  may include a seal  141  that substantially seals the motor  130  and/or other parts of the integrated motor system  115  from the lubricant  139 . In some embodiments, the seal  141  may be an O-ring that substantially prevents the lubricant  139  from leaking from the cavity  192  into the motor cavity  138 . 
     Furthermore, the integrated motor system  115  may include a controller  155 . The controller  155  may include a processor, computerized memory, and/or other components of a computerized control system. The controller  155  generates control signals for controlling operation of the motor  130 . The controller  155  may be configured to generate control signals and transmit those signals to the motor  130  for changing the speed of the motor between at least two speeds. In some embodiments, the controller  155  may be configured to turn the motor  130  ON and OFF (i.e., change the speed of the motor  130  from zero RPMs to a positive RPM value). In additional embodiments, the controller  155  may be configured to adjust the speed of the motor output shaft  132  between a plurality of predetermined set speeds (e.g., change the speed of the motor  130  between a first speed, a second speed, a third speed, and an nth-speed, each having different RPM values). 
     Moreover, the controller  155  may automatically control the motor  130  in some embodiments. In other embodiments, the integrated motor system  115  may allow user commands to be supplied to the controller  155  such that the user “manually” turns the motor  130  ON and OFF and/or varies the speed of the motor  130 . In further embodiments, the controller  155  may be configured for automatic control of the motor  130  in some scenarios and manual control of the motor  130  in other scenarios. 
     The integrated motor system  115  may also include a user interface  159 . The user interface  159  may include buttons, switches, a display, a speaker, and/or other instruments. The user interface  159  may be in communication (e.g., via wires and/or through wireless communication) with the controller  155 . With the user interface  159 , a user may supply input to the controller  155 , and the controller  155  may generate and send corresponding control signals to the motor  130 . The controller  155  may also generate and send control signals back to the user interface  159  for outputting information (e.g., via a display or speaker) to inform the user of the status of the integrated motor system  115 . The user interface  159  may be provided in any suitable location, for example, within a cockpit of the vehicle  12 . 
     Also, the integrated motor system  115  may include at least one sensor  157 . The sensor  157  may be configured to observe a condition that necessitates use of the motor system  115 . For example, in some embodiments, the sensor  157  is configured to observe that the main engine  14  has shut down. As a result, the sensor  157  outputs a corresponding signal to the controller  155 , and the controller  155 , in turn, outputs a control signal to the motor  130  to turn ON the motor  130 . 
     Operations of the engine system  10  will now be discussed with reference to  FIGS. 1 and 2 . For purposes of discussion, the following sequence will be described: (1) startup of the main engine  14  using the ATS  110 ; (2) independent operation of the main engine  14 ; and 3) shutdown and cooling of the main engine  14  while using the integrated motor system  115 . It will be appreciated that other operation sequences may be employed that fall within the scope of the present disclosure. 
     To begin startup of the main engine  14 , air is supplied to the ATS  110  via the flow path  114 . This air input pushes the turbine blades  128  to rotate the wheel  123  and shaft  124 . Resultant torque transfers through the gear train  140  of the ATS  110  to the main engine input member  20  to rotate the movable parts  18  of the main engine  14 . In some embodiments, air is continuously supplied to the ATS  110  until the speed of the movable parts  18  reach a predetermined speed. This speed may be referred to as a “combustion speed” or “lightoff speed”. 
     Once the movable parts  18  of the main engine  14  reach combustion speed, fuel may continue to be injected into and combusted within combustion chambers of the main engine  14 . The power of combustion increases the speed of the movable parts  18  to a so-called “operational speed” or “cutout speed” and allows the main engine  14  to operate independent of the ATS  110 . Thus, air supplied to the flow path  114  of the ATS  110  may be cut off. 
     The main engine  14  may be operated independently for a desired time. Then, during shutdown of the main engine  14 , fuel can be cut off to cease combustion in the main engine  14 , causing the movable parts  18  to slow down. At a predetermined time, the integrated motor system  115  may be operated to keep the movable parts  18  rotating at a predetermined speed. Specifically, the controller  155  may turn the motor  130  ON to supply the resultant motor torque to the main engine input member  20 . 
     In some embodiments, the sensor  157  observes a condition indicative of shutdown of the main engine  14 , the sensor  157  sends a corresponding signal to the controller  155 , and the controller  155  in turn sends a control signal to the motor  130  to automatically turn ON the motor  130 . In other embodiments, a user provides input to the controller  155  via the user interface  159 , and the controller  155  in turn sends a control signal to the motor  130  to manually turn ON the motor  130 . 
     Torque generated by the motor  130  transfers to the motor output gear  134 , and then to the ring gear  148 . The ring gear  148  then, in turn, rotates the hub gear  162  of the clutch  160 , and the torque is transferred to the main engine input member  20  for maintaining rotation of the movable parts  18  of the main engine  14 . In some embodiments, the motor  130  may cause the movable parts  18  of the main engine  14  to rotate at a speed that is less than both the operational speed and the combustion speed of the main engine  14 . The motor  130  may operate continuously for a predetermined period of time until the main engine  14  has sufficiently cooled. Then the controller  155  may turn the motor  130  OFF. 
     In additional scenarios, the motor  130  is operated during a startup procedure of the main engine  14 . For example, the controller  155  may turn the motor  130  ON to rotate the movable parts  18  at a speed that is less than both the operational speed and the combustion speed. Then, air may be supplied to the ATS  110  such that the ATS  110  increases the speed of the movable parts  18  to the combustion (i.e., lightoff) speed. Next, the main engine  14  may be operated independent of the ATS  110 . 
     It will be appreciated that the torque path from the motor  130  to the ring gear  148  of the ATS gear train  140  is substantially one-way in the illustrated embodiment. This is because the motor clutch  154  unclutches to prevents torque from travelling back from the ring gear  148  toward the motor  130  (e.g., during startup of the main engine  14 ). 
     Similarly, it will be appreciated that the torque path from the motor  130  to the main engine input member  20  is substantially one-way in the illustrated embodiment. This is because the ATS clutch  160  is disposed along the torque path between the motor  130  and the main engine input member  20 . The ATS clutch  160  is disposed in its clutched position to transfer torque from the motor  130  to the main engine input member  20 . On the other hand, the ATS clutch  160  moves to its unclutched position to prevent torque from travelling back from the main engine input member  20  toward the motor  130  (e.g., during combustion within the main engine  14 ). 
     Thus, the integrated motor system  115  may be used for providing substantially even cooling of the main engine  14 . More specifically, the motor  130  maintains rotation of the movable parts  18  after shutdown such that heat is transferred evenly through the movable parts  18 . As such, the main engine  14  is less likely to be damaged or deformed by temperature gradients. 
     Also, the motor system  115  may rely on at least part of the ATS gear train  140  for providing the predetermined gear reduction to the main engine input member  20 . Likewise, the motor system  115  may rely on the ATS clutch  160  for providing one-way torque transfer to the main engine input member  20 . Accordingly, the motor system  115  may be integrated into the ATS  110  in a compact and, yet, effective manner. 
     Referring now to  FIG. 3 , the integrated motor system  215  is illustrated according to additional embodiments. The embodiment of  FIG. 3  may be substantially similar to the embodiment of  FIG. 2 , except as noted. Components in  FIG. 3  that correspond to those of  FIG. 2  are indicated with corresponding reference numbers, increased by 100. 
     The integrated motor system  215  may include a motor  230 , which rotates and drives a motor output shaft  232 . The motor system  215  may also include a motor output gear  234  and a frangible member  256 , similar to the embodiments discussed above. 
     The motor output gear  234  may be moveable between a first position and a second position. In  FIG. 3 , the first position is shown in phantom, and the second position is shown in solid lines. In the first position, the motor output gear  234  engages the outer diameter part  252  of the ring gear  248  of the ATS gear train  240 . In the second position, the motor output gear  234  is spaced apart from and disengaged from the ring gear  248 . Accordingly, when the motor output gear  234  is in the first position, the motor output gear  234  is able to deliver torque from the motor  230  to the ring gear  248  of the ATS  210  (e.g., during main engine shutdown). On the other hand, when the motor output gear  234  is in the second position, torque is unable to be delivered from the motor  230  to the ring gear  248 . 
     The integrated motor system  215  may also include an actuator  274  that is configured to move the motor output gear  234  between the first and second positions. In some embodiments, the actuator  274  is configured to move the motor output gear  234  substantially linearly between the first and second positions. For example, the actuator  274  may include a solenoid  276  with a shaft  277  and a pivot arm  278 . The pivot arm  278  may include a first end  279  that engages the shaft  277 . The pivot arm  278  may also include a second end  280  that includes at least one abutment member  282 . The pivot arm  278  may be mounted to pivot about a pivot member  289 . The abutment member  282  may engage one or more engagement members  272 , which are included on the output shaft  232  of the motor  230 . 
     The controller  255  may be operably connected to the motor  230  as well as the solenoid  276 . The motor system  215  may also include the sensor  257  and the user interface  259  of the type discussed above. 
     Operation of the integrated motor system  215  will now be discussed according to exemplary embodiments. During startup of the main engine, the motor output gear  234  may be disposed in the second position, disengaged from the ring gear  248 . Accordingly, torque from the ring gear  248  will not transfer to the motor output gear  234  during main engine startup. Also, during combustion and normal operations of the main engine, the motor output gear  234  may remain in the second position, disengaged from the ring gear  248 . However, during shutdown of the main engine, the controller  255  may generate and send a control signal to the actuator  274  to move the motor output gear  234  to the first position to engage the ring gear  248 . Specifically, in the illustrated embodiment, the controller  255  may send a control signal to the solenoid  276 , which retracts the shaft  277  into the solenoid  276 . Movement of the shaft  277  moves the first end  279  of the arm  278  and, thus, pivots the arm  278  about the pivot member  289 . As the arm  278  pivots, the abutment members  282  push the engagement members  272  to ultimately move the output gear  234  linearly toward engagement with the ring gear  248  (i.e., toward the first position). With the output gear  234  in the first position, the motor  230  may be used to deliver torque to the main engine for engine cooling as discussed above. The controller  255  may also send control signals to the solenoid  276  for returning the output gear  234  to the second position so that output gear  234  disengages from the ring gear  248  once the main engine has sufficiently cooled. 
     The integrated motor system  215  of  FIG. 3  may provide substantially even cooling for the main engine, similar to the embodiments of  FIGS. 1 and 2 . Also, the motor system  215  may be compact and, yet, effective for cooling purposes. Additionally, in some embodiments, the motor system  215  may not need a clutch (e.g., motor clutch  154 ) of the type discussed above with respect to  FIG. 2 . Instead, the actuator  276  may be relied upon for preventing torque from being transferred from the ring gear  248  toward the motor  230  (i.e., when the output gear  234  is in the second position). In other embodiments, the integrated motor system  215  may include a clutch (e.g., similar to the clutch  154  discussed above). 
     While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the present disclosure. It is understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the present disclosure as set forth in the appended claims.