Abstract:
A test fixture for testing directional pilot valves as used in connection with turbine engine thrust reversers, and an associated method of use. In a particular embodiment, the test fixture has a base and at least one support mounted to the base to support the directional pilot valve. At least one fastener permits attachment of the directional pilot valve to the support. An adjustable actuator is also mounted to the base and is capable of stroking the directional pilot valve to simulate valve positions that may be encountered in operation of the valve. The adjustable actuator is also capable of maintaining a force, as set by a technician, against the directional pilot valve.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates generally to pilot valves for use in aircraft or gas turbine engine applications, and in particular to an apparatus and related method for testing aircraft pilot valves that can be used in connection with turbine engine thrust reversers.  
         BACKGROUND OF THE INVENTION  
         [0002]    Directional air flow pilot valves may serve a variety of useful purposes in connection with a gas turbine aircraft turbine engine, such as to control the engaging and disengaging of an aircraft engine&#39;s thrust reverser. In general, aircraft turbine engine thrust is directed towards the rear of the plane. Upon landing, in an effort to diminish lift as well as slow the aircraft, the direction of thrust may partially be reversed with the use of a thrust reverser. The developer of the present inventions, Honeywell International, Inc., has for years successfully designed, developed, and manufactured turbine engines that have directional pilot valves used in connection with thrust reversers.  
           [0003]    Aircraft air flow pilot valves are generally known and reliable devices used in the operation of aircraft control systems. Directional air flow pilot valves are valves that permit air flow in a specific direction. One type, known as a directional pilot valve (DPV), has a sealing rod assembly, which is moved along the longitudinal axis of the DPV in and out of the valve housing assembly. Actuated movement of the sealing rod assembly is commonly referred to as stroking. The outer limit of movement is commonly known as maximum stroke length. Generally speaking, the flow rate of air through the DPV will change as the stroke of the valve is increased or decreased, because the valve is opened and/or closed by the linear motion of the sealing rod.  
           [0004]    Proper calibration of the DPV helps to ensure proper operation of the thrust reverser. As initially manufactured, a DPV will operate to control passage of air through the valve assembly at a known rate. Over time, due to internal wear, debris and foreign matter which may enter the valve unintentionally, and other factors, the flow rate of the directional valve may significantly change. Such a change in flow rate may result in the operation of the DPV outside of the desired calibration range. However, as flight control systems are redundant, conventional gas turbine engines and thrust reversers are operationally safe and reliable despite the foregoing variations in calibration of a DPV.  
           [0005]    In operation, a DPV may have two general forces acting upon it—the first is a constant physical load force applied against the opening of the valve and the second is an air pressure force applied in a direction opposite to the physical load force. To test a DPV for proper calibration, it is desirable to therefore apply forces in an opposing manner to simulate the valve&#39;s operational response. To calibrate the valve, these forces are applied in a known and controlled fashion while the stroke of the valve is varied. In general, such a calibration test can measure the effective air pressure and leakage when the DPV is in a seated position, as in closed, and the volume of air flow when the DPV is in an open position.  
           [0006]    At present, a technician performing a calibration measurement test upon a DPV attempts to physically hold, apply force and measure pressure and flow rate—a physically demanding and complex process that may result in inaccurate measurement. If a DPV cannot be properly calibrated, the entire DPV is replaced with a new valve or remanufactured to original specifications to ensure proper operation.  
           [0007]    The replacement with a new valve is wasteful of resources and costly. The one alternative is to remanufacture the valve. However, remanufacturing is a complex process involving specialized tooling, training and a time-consuming assembly and test processes. With either replacement or remanufacture, the flow rate calibration is based upon the design specification and not the actual flow rates of the given valve. Thus, even with new replacement or remanufacture there is a possibility of a calibration that is inaccurate to some degree  
           [0008]    Hence, there is a need for an improved DPV calibration system with improved characteristics to overcome one or more of the drawbacks identified above. The present invention satisfies one or more of these needs.  
         SUMMARY OF THE INVENTION  
         [0009]    This invention provides an improved apparatus and related method for testing aircraft directional pilot valves used in connection with thrust reversers.  
           [0010]    In particular, and by way of example only, one embodiment of the present invention provides a test fixture assembly for testing a general aviation directional pilot valve having a housing assembly, an inlet, and an opposing actuating sealing rod assembly. The test fixture assembly provides a supporting means for supporting the housing assembly and an attaching means for attaching the housing assembly to the supporting means. Also provided is an actuating means for actuating the sealing rod assembly within the supported housing assembly. In addition, the test fixture provides a binding means for binding the actuating means so that the sealing rod assembly is held at a specific point of actuation.  
           [0011]    Moreover, according to an embodiment thereof, the invention may provide a test fixture assembly for testing a general aviation directional pilot valve having a housing assembly, an inlet, and an opposing actuating sealing rod assembly. The test fixture assembly provides a base and at least one support mounted to the base to support the housing assembly. Further, the test fixture assembly provides at least one fastener to secure the housing assembly to the support and an adjustable actuator mounted to the base. The actuator sized to engage the sealing rod assembly to longitudinally move the sealing rod assembly and hold it in at least one calibration location.  
           [0012]    In yet another embodiment, the invention may provide a method of testing a general aviation directional pilot valve having a housing assembly, an inlet, and an opposing actuating seating rod assembly using a test fixture. The test fixture provides a base, a support, and an adjustable actuator. The method of testing involves attaching the directional pilot valve housing assembly to the test fixture and applying an initial load force to the sealing rod assembly to move it to an initial position to initialize the sealing rod assembly. The actuator is then adjusted to hold the sealing rod assembly in the initial position. Air pressure is supplied to the directional pilot valve inlet and a measurement taken of the air flow through the directional pilot valve with the sealing rod at the initial position. The actuator is then adjusted to move the sealing rod to a second position and measuring the air flow through the directional pilot valve with the sealing rod at the second position is taken.  
           [0013]    These and other objects, features and advantages of the preferred apparatus and method will become apparent from the following detailed description, taken in conjunction with the accompanying drawings which illustrate, by way of example the principles of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1A is a perspective view of the directional pilot valve test fixture according to the present invention;  
         [0015]    [0015]FIG. 1B is a perspective view of the directional pilot valve test fixture of FIG. 1;  
         [0016]    [0016]FIG. 2A is a plan view of the directional pilot valve being initialized on the test fixture of FIG. 1;  
         [0017]    [0017]FIG. 2B is a plan view of the initialized pilot valve on the test fixture of FIG. 1 being tested in the initial position;  
         [0018]    [0018]FIG. 3A is a plan view of the directional pilot valve being adjusted on the test fixture of FIG. 1 to permit further testing; and  
         [0019]    [0019]FIG. 3B is a plan view of the directional pilot valve being tested in a second position on the test fixture of FIG. 1. 
     
    
     DETAILED DESCRIPTION  
       [0020]    Before proceeding with the detailed description, it is to be appreciated that the present invention is not limited to use or application with a specific type of directional pilot valve (DPV). Thus, although the present invention is, for the convenience of explanation, depicted and described with respect to one type of a DPV as may be used in connection with a turbine engine thrust reverser, this invention may be applied to other types and styles of DPVs used in other turbine engine applications.  
         [0021]    Turning now to the description and with reference to FIG. 1A, a DPV test fixture  100  is shown as one embodiment of the invention. The test fixture  100  has a base  102 , a support  104 , an adjustable actuator  106 , and an aligner  108 . The support  104  further provides threaded screw sockets  110  which serve to attach and secure the housing of a DPV to the test support at substantially the proper elevation for alignment with the adjustable actuator  106 .  
         [0022]    In at least one embodiment, the adjustable actuator  106  may be a threaded rod  118  mounted to a grip  120 . As shown, the longitudinal axis  122  of threaded rod  118  is substantially parallel to the longitudinal axis  124  of the base  102 . Threaded rod  118  passes through mated threaded hole  126  in plate  128 . As shown, plate  128  is substantially perpendicular and transverse to base  102 . Threaded rod  118  may also be hollow with openings  130  and  132  at either end (see FIGS. 1A and 1B), such that a shaft or other tooling implement may be passed through threaded rod  118 .  
         [0023]    Grip  120  may be sized and shaped to be easily grasped and rotated by a technician. More specifically, as grip  120  is rotated by a technician, the rotation of grip  120  is directly imparted to threaded rod  118 . It is to be understood and appreciated that rotation, represented by arrows  134 , of grip  120  imparts lateral motion, represented by arrows  136 , to threaded rod  118  towards or away from support  104 .  
         [0024]    In at least one embodiment, threaded rod  118  and grip  120  may be fabricated from a unitary block of metal. Under appropriate circumstances, other methods of coupling may be employed such as glue, welding, press fitting, threaded fitting, or set screws.  
         [0025]    The threads of rod  118  and the threads of mated threaded hole  126  may be sufficiently fine and snug to each other such that threaded rod  118  will remain at a fixed position when the technician ceases rotation of grip  120 . In addition, in at least one embodiment, force along the longitudinal axis  122  of threaded rod  118  does not impart a rotation of rod  118  through the threads of hole  126 . More specifically, rod  118  may support a load force without spontaneous rotation. In at least one embodiment, the threads of rod  118  and hole  126  are substantially about ½″-13 thread.  
         [0026]    Under appropriate circumstances threaded rod  118  may directly contact the distal end of a DPV undergoing testing. However, as shown in FIG. 1B, use of adapter  138  may be employed to improve alignment with, and application of force to, the DPV undergoing testing.  
         [0027]    In at least one embodiment, adapter  138  is substantially sized to receive the distal end a DPV undergoing testing, see FIGS. 2 through 3. In addition, adapter  138  may incorporate a swivel bearing such that it is free to rotate about longitudinal axis  122 . More specifically, adapter  138  may remain aligned in a specific orientation independent of the rotation of threaded rod  118 . Use of a swiveling adapter  138  may help insure that the force applied to the DPV during testing is free of rotational torsion force born by the rotation of threaded rod  118 . Under appropriate circumstances, the technician may have a selection of adapters to accommodate different DPVs.  
         [0028]    Fine alignment adjustment of the DPV to the actuator, if required, may be achieved with the use of aligner  108 . More specifically, in at least one embodiment aligner  108  is a threaded rod  112  extending perpendicularly from a mated threaded socket  116  in base  102 , see FIG. 1A. Rotation of threaded rod  112 , represented by arrows  140  will raise or lower rod  112 , as represented by arrows  142 , relative to base  102 . A lock-nut  114  may be employed to further secure threaded rod  112  at a desired height. Under appropriate circumstances, other means of height adjustment may be employed.  
         [0029]    As shown, support  104  is a solid block with threaded screw sockets  110 . In at lest one embodiment, the coupling of support  104  to base  102  is accomplished with bolts installed from the underside of base  102 . In addition, the coupling of plate  128  to base  102  is accomplished with bolts installed from the underside of base  102 . Under appropriate circumstances, alternative coupling or joining means, such as welding, may be employed. In addition, support  104  may be composed of independent members, and or adjustable in its location upon base  102  so as to accommodate aviation DPVs of different sizes. Further, under appropriate circumstances, a portion of base  102  may be formed, such as by bending, to rise at substantially a right angle to the remaining portion of base  102 . Such formed portion may be drilled and threaded with hole  126  so as to substantially assume the role of plate  128 .  
         [0030]    In at least one embodiment, test fixture  100  may provide securing holes  144  permitting test fixture  100  to be secured to a work surface by pins, screws, bolts, or other similar device.  
         [0031]    Having described the above physical embodiment of a DPV test fixture  100 , another embodiment relating to the method of employing test fixture  100  to test an aviation DPV will now be described with reference to FIGS. 2A, 2B,  3 A and  3 B. It will be appreciated that the described method need not be performed in the order in which it is herein described, but that this description is merely exemplary of one method of using the test fixture  100  in accordance with the present invention.  
         [0032]    During routine aircraft maintenance, a thrust reverser DPV  281  may be made available for calibration testing. A typical thrust reverser DPV  281  is understood and appreciated to have a housing assembly  283 , an inlet  285  and opposite thereto an actuating sealing rod assembly  287 .  
         [0033]    In general, technician may commence the calibration testing procedure by attaching the DPV  281  to test fixture  100 . More specifically, housing assembly  283  is attached to support  104 . If elevational alignment adjustment of DPV  281  is required, the technician may adjust aligner  108 . Typically, the DPV&#39;s employed with turbine engine thrust reversers are substantially standardized. In light of such standardization, after an initial setting, aligner  108  may not require further adjustment in repeated testing applications.  
         [0034]    As shown in FIG. 2A, the technician applies an initial load force, represented by arrow  200 , to the sealing rod assembly  287 . In at least one embodiment, the initial load force  200  is applied with the use of a force gage  202 . Force gage  202  is understood and appreciated to have a force applying shaft  204  and a force indicator, such as dial indicator  206 . More specifically, force gage  202  may be a Chatillon force gage, commonly known and available in the industry. The technician may determine the appropriate initial load force by referencing the design specifications for DPV  281 .  
         [0035]    To apply the initial load force  200 , the technician may slide force shaft  204  through threaded rod  118  such that force shaft contacts the distal end  289  of sealing rod assembly  287 . The application of initial load force  200  seats sealing rod assembly  287 . More specifically, the initial load force  200  initializes DPV  281  to a closed position in accordance with initial design specifications. The technician may observe the precise initial load force  200  applied by viewing dial indicator  206 . In at least one embodiment, the initial load force  200  may be substantially about 20.0 pounds per square inch. In at least one embodiment, the initial load force  200  may be substantially about 30.0 pounds per square inch.  
         [0036]    Under appropriate circumstances, the technician may observe the force required to initiate actuation of the sealing rod assembly  287  toward the seated position. In at least one embodiment, the measured force to initiate actuation is between about 3.0 to 5.0 pounds per square inch.  
         [0037]    With a specific initial load force  200  applied and maintained, as reported by dial indicator  206 , the technician may rotate grip  120  as represented by arrow  208 . Such rotation is understood and appreciated to drive threaded rod  118  and adapter  138  towards the distal end  289  of sealing rod assembly  287 , represented by arrow  210 . The technician continues adjusting actuator  106  until adapter  138  engages the distal end  289  of sealing rod assembly  287 , and holds it at the initialized position  212 . As the sealing rod assembly  287  is held by actuator  106 , the force gage  202  may be removed.  
         [0038]    An initial dimension measurement  214  may be taken from the base  291  of DPV  281  to initial position  212 , and compared to design specifications. In at least one embodiment, the desired initial dimension measurement  214  may be substantially about 4.144 to 4.150 inch. In at least one embodiment, the desired initial measurement  214  may be substantially about 4.744 to 4.750 inch. Should initial dimension measurement  214  of DPV  281  fall outside of the design specification, the technician may note DPV  281  as having failed. Failed valves may be rebuilt and/or reworked as may be deemed appropriate.  
         [0039]    An air supply hose  220  with pressure gage  222  and flow gage  224  is connected to air inlet  285 . Under appropriate circumstances the pressure and flow rate gages may be a combined unit or apparatus. More specifically, the technician may employ the use of an industry standard air flow measuring system, such as the Daniel&#39;s Flow Measuring System.  
         [0040]    With respect to FIG. 2A, to perform a leakage calibration test, the technician supplies pressurized air, represented by arrows  226 , through supply hose  220  to the initialized DPV  281 . A substantially precise reading of the air pressure supplied may be to displayed as pressure  230  by pressure gage  222 . In at least one embodiment, the air pressure supplied to inlet  285  is about 49 to 51 pounds per square inch.  
         [0041]    As the initial force load applied by the technician is maintained by actuator  106  as adjusted in FIG. 2A, the technician need not be concerned with maintaining the initial load force as the pressurized air  226  is applied. More specifically, as test fixture  100  holds DPV  281  in a substantially fixed position relative to actuator  106 , the addition of air pressure does not substantially affect the initial position  212 . In addition, the initial load force  200  applied by the technician is understood to remain unchanged with the force of air pressure through DPV  281  being directly additive. As such, the present invention eliminates the possibility of the technician unintentionally increasing or decreasing the initial load force as may be experienced in the prior art system of hand held testing.  
         [0042]    Air flow through DPV  281 , commonly known as leakage, represented by dotted arrows  228  may occur from vent  293 . A substantially precise reading of the air flow rate of leakage  228  may be displayed as flow rate  232  by flow gage  224 . In at least one embodiment, the air flow rate of leakage  228  is less than about 0.036 pounds per minute. Should the air flow rate of leakage  228  exceed design specifications, the technician may note DPV  281  as having failed.  
         [0043]    Testing of the stroke and flow rate of DPV  281 , may best be appreciated with respect to FIGS. 3A and 3B. The technician adjusts actuator  106  to open DPV  281 . More specifically, the technician may rotate grip  120 , represented by arrow  300 . Such rotation is understood and appreciated to drive threaded rod  118  and adapter  138  away from support  104 , represented by lateral motion arrow  302 . In at least one embodiment the lateral motion  302  away from support  104  actuates the sealing rod assembly  287  away from the initial seated position. Under appropriate circumstances, air pressure within DPV  281  may provide an assisting force in actuating the sealing rod assembly  287  as adapter  138  recedes.  
         [0044]    The technician adjusts actuator  106  to stroke sealing rod assembly  287  to a second position  304 . The technician may use measurement tool  306  to be substantially precise in determining when the distal end  289  of sealing rod assembly  287  has been adjusted second position  304 , as measured from the base  291  of DPV  281 . The second position  304  may determined by manufacturing specifications.  
         [0045]    In at least one embodiment, the difference  308  between the initial position  212  and second position  304  is between about 0.34 to 0.38 inch. If DPV  281  can not be actuated to the second position, the technician may note DPV as failing the stroke test.  
         [0046]    To perform the flow test, the technician may adjust the air pressure provided to inlet  285  to a second air pressure, represented by arrows  310 , and reported as pressure  312  on pressure gage  222  (see FIG. 3B). In at least one embodiment, the second air pressure may be substantially about 19 to 21 pounds per square inch as reported by pressure gage  222 .  
         [0047]    Air flow through DPV  281 , represented by arrows  314  may occur from vent  293 . As described above, test fixture  100  substantially maintains the position of DPV  281  relative to actuator  106 , without substantial regard to the presence or absence of air pressure within DPV  281 . A substantially precise reading of the air flow  314  may be displayed as flow rate  316  by flow gage  224 . In at least one embodiment, the flow rate  316  is at least 2.6 pounds pre minute. Should the air flow rate  316  not meet or exceed design specifications for minimum flow rate, the technician may note DPV  281  as having failed.  
         [0048]    As test fixture  100  provides a technician with the ability to specifically identify a failing DPV  281 , refurbishment of failing DPV  281  may be appropriately considered and evaluated against the cost of manufacturing a new valve. In addition, test fixture  100  provides a technician with the ability to insure that new a DPV  281  is indeed fabricated to proper design specifications, and correct manufacturing errors prior to installation in turbine engine thrust reversers. It should be appreciated that the valves and dimensions described above will vary according to the particular DPV tested in test fixture  100 .  
         [0049]    The adjustable features of the test fixture  100  may permit the testing of different DPV&#39;s without requiring separate and distinct test fixtures. Such adjustability to accommodate different DPV&#39;s is desirable for it improves technician speed and efficiency when testing different DPV&#39;s as retrieval of an additional test fixture from inventory is unnecessary. In addition, the adjustability to accommodate other DPV&#39;s reduces the volume of specialized test fixtures which might be held in inventory and reduces costs incurred in obtaining and/or manufacturing multiple specialized test fixtures,  
         [0050]    While the invention has been described with reference to the preferred embodiment, it will be understood by those skilled in the art that various alterations, changes and improvements may be made and equivalents may be substituted for the elements thereof and steps thereof without departing from the scope of the present invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from the essential scope thereof Such alterations, changes, modifications, and improvements, though not expressly described above, are nevertheless intended and implied to be within the scope and spirit of the invention. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.