Abstract:
A starter motor has a housing. The housing receives the starter motor and a plurality of locations to receive lubricant. The lubricant supply system shares a lubricant source with a main gas turbine engine to be started by the starter motor. The lubricant supply system has a shutoff valve. The shutoff valve is opened when starter motor is being driven to start a main gas turbine engine. The shutoff valve is generally closed once the main gas turbine engine is started.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This application relates to an air turbine starter for a gas turbine engine having a lubrication system which is shared with the gas turbine engine. 
         [0002]    Aircraft include a plurality of gas turbine engines. As known, a gas turbine engine on an aircraft includes a fan delivering air into a compressor and into a bypass duct. The air is compressed in the compressor and delivered into a combustion section where it is mixed with fuel and ignited. Products of this combustion pass downstream over turbine rotors driving them to rotate. 
         [0003]    The turbine rotors drive shafts which, in turn, drive the fan and compressor. 
         [0004]    Typically it is necessary to begin rotation of the shafts and, hence, the compressor, fan and turbine rotors prior to start-up of the main gas turbine engines on an aircraft. Thus, starter motors are provided for starting the gas turbine engine. One such known starter is an air turbine starter. 
         [0005]    Both the main gas turbine engine and the air turbine starter require lubrication. For a number of reasons, it is desirable to have a single lubricant system providing lubricating fluid to both the main gas turbine engine and the air turbine starter. The air turbine starter is typically only driven at start-up of the main gas turbine engine. Thus during most flight situations, there is no need for lubrication at most locations within the air turbine starter. 
         [0006]    On the other hand, lubrication must be supplied to the gas turbine engine during its operation. 
         [0007]    In the prior art, should there be a failure in the air turbine starter, it is possible that lubricant will be lost from the system, such that there is insufficient lubricant for the main gas turbine engine. 
       SUMMARY OF THE INVENTION 
       [0008]    A starter motor has a housing and a plurality of locations to receive lubricant. A lubricant supply system is shared with a main gas turbine engine to be started by the starter motor. The lubricant supply system has a shutoff valve. The shutoff valve is opened when the air turbine starter is being driven to start the main gas turbine engine. The shutoff valve is generally closed once the main gas turbine engine is started. 
         [0009]    These and other features may be best understood from the following drawings and specification. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  shows an air turbine starter and main gas turbine engine. 
           [0011]      FIG. 2A  shows a first embodiment. 
           [0012]      FIG. 2B  shows the first embodiment in a second position. 
           [0013]      FIG. 3A  shows a second embodiment. 
           [0014]      FIG. 3B  shows the second embodiment in a second position. 
           [0015]      FIG. 4A  shows a third embodiment. 
           [0016]      FIG. 4B  shows the third embodiment in a second position. 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    An aircraft  20  is shown schematically having a main gas turbine engine  22  with a shaft  24 , and gas turbine engine components  26 . As known, the components include a fan, a compressor, a combustor and a turbine. The turbine, compressor and fan all rotate with shaft  24  or, in some instances, also with a second shaft. 
         [0018]    As shown schematically, an air turbine starter  40  is within a housing  41  and includes structure for receiving pressurized air, and driving a shaft  28 . Shaft  28 , in turn, drives the shaft  24  at start-up of the main gas turbine engine  22 . The detail of the air turbine starter  40  may be as known and it is not illustrated in this Figure, other than schematically. A clutch body  30  connects the shaft  28  through a shaft  43  of the air turbine starter  40 , shown schematically. 
         [0019]    An oil pump  54  delivers lubricant through a line  52  into a flow restrictor  50  and into the housing  41 . A lubricant level  32  is shown within the housing  41  and a transfer tube  44  extending through an internal wall  302  of the housing  41 , which separates the housing into housing portions  300  and  301 . Housing portion  300  receives clutch  30  and shaft  28 , and portion  301  receives the air turbine starter  301 . 
         [0020]    In this embodiment, oil downstream of the transfer tube  44  passes through a line  48  and lubricates a number of locations  42 , which may be bearings or seals associated with the air turbine starter  40 . As shown, a shutoff valve  45  is supplied within the transfer tube  44 , in a first embodiment. Oil is also delivered in some manner from the line  46  into a scupper  36 , where it is supplied to output bearings  34  associated with the shaft  28 . 
         [0021]    As known, during startup of the main gas turbine engine  22  the air turbine starter  40  is driven to drive the shaft  28  to, in turn, rotate the shaft  24  and cause the engine  22  to start. Once the engine has started, the air turbine starter  40  is shut down. The clutch  30  will open. However, the shaft  28  is now driven by the shaft  24 . Thus, the lubricant supplied to the bearings  34  is important at all times during operation. 
         [0022]    As shown in  FIG. 2A , the shut off valve  45  may include a restriction  164  delivering oil into the scupper  36  and, hence, the bearings  34  at a location which is upstream from a valve element  60 . The valve element  60  is biased by the force of the lubricant pressure in the supply line  46  against a spring force  63 . As shown in the position of  FIG. 2A , the spring force  63  has biased the valve element  60  away from a valve stop  62 , such that lubricant can flow from the line  46  through the aperture  64  in valve element  60  and into the output line  48 . 
         [0023]    The shut off valve  45  is shown somewhat schematically and any known pressure actuated valve may be utilized. 
         [0024]    As the main engine  22  increases its speed, the pressure of the lubricant on line  46  will also increase. At some point, the pressure on the line  46  will become sufficient to overcome the spring force  63 , and the valve element will be driven against the valve stop  62 , such that aperture  64  is blocked and significant lubricant is no longer delivered to the line  48 . 
         [0025]    Now, should the air turbine starter  40 , fail as described above, the lubricant will not be lost from the system and the main gas turbine engine  22  will still have sufficient lubricant. Also, the bearing  34  will still be provided with lubricant, as the tap line  163  and restriction  164  are at a location upstream of the point where the valve element  60  will be closed. 
         [0026]    While the lubricant leading to the output line  48  is shown to pass through the spring member providing the spring force  63 , it will be understood to a worker of ordinary skill in the art, this is a schematic representation and the valve may deliver the lubricant to downstream locations in another manner. 
         [0027]      FIG. 3A  shows another embodiment shut off valve  150 . The shut off valve is shown schematically to include the stop  62 , valve element  60 , aperture  64 , and the output line  148 , which replaces the output line  48  of  FIG. 1 . There is a restriction  151  on the line  46  upstream of the valve  60 . This embodiment  150  may replace the restrictor  50  of the  FIG. 1  embodiment. 
         [0028]    As shown in the position of  FIG. 3A , the pressure on the line  46  is relatively low and the spring force  63  moves the valve  60  to the open position, such that lubricant may flow through the aperture  64 . 
         [0029]    As shown, a tap  152  from the output line  148  delivers the lubricant back through the restrictor  164  into the scuppers  36 . 
         [0030]    As shown in  FIG. 3B , the main gas turbine engine  22  has now begun operation, such that the pressure on line  46  has become sufficient to overcome spring force  63 . The aperture  64  is now closed. However, the valve  60 / 62  will still have some leakage. Thus, for purposes of this application, the shut-off valves could be said to be generally closed in this position. The leakage across the valve  60 / 62  will pass into the tap line  150 , such that lubricant is still delivered to the scupper  36  during this time of operation. 
         [0031]      FIG. 4A  shows yet another shut-off valve embodiment  250 , again having a valve  62 / 64  and a spring bias  63 . In the position shown in  FIG. 4A , the lubricant can pass freely across the valve element  60 , into output line  78 , and eventually to a downstream output line  248 . A U-pipe  80  is provided between the lines  78  into  48  to gather a leakage lubricant, and deliver it through the restriction  164  back to the scupper  36 . 
         [0032]    As shown in  FIG. 4B , the shut-off valve  250  is now closed. However, there is leakage, and that leakage lubricant will accumulate in the bottom of the U-pipe  80 , such that lubricant will be delivered to the scupper  36 . 
         [0033]    It should be understood the shut-off valve can be located anywhere along the line  46 . The valve can be a separate component, or could be part of a subassembly, for example with the restrictor  50  of  FIG. 1 . While an air turbine starter is disclosed, other starter motors may benefit from these teachings. 
         [0034]    Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.