Abstract:
Methods and systems for maintaining a machine using an in-situ vehicle (IV) is provided. The IV may be used with a machine that includes a work-piece and an interference body positioned proximate a surface of the work-piece such that a relatively small gap extends between the work-piece and the interference body. The method includes transporting the IV from external to the machine into the gap, positioning the IV in the gap such that at least a portion of the IV circumscribes a work area of the work-piece, locking the IV between the work-piece and the interference body, and manipulating a tool coupled to the IV from external to the machine, the tool configured to transfer a component between the work-piece and a storage cassette on the IV.

Description:
BACKGROUND 
     This invention relates generally to rotatable machines and more particularly, to methods and systems for in-situ balancing of rotors of rotatable machines. 
     During the lifetime of a rotating machine, periodic balancing of the rotating member is performed. During operation of a mechanical machine such as a fan or turbine, wear or damage may induce a vibration in the machine. For an electrical machine such as a generator or motor an increase in vibration may be due to copper shorts. Additionally, repair to a rotor such as a rewind or machining may also alter the center of gravity of the rotor resulting in an increase in vibration. To reduce the vibration of the operating machine, an imbalance is quantified and canceling weights are generally attached, removed, or moved on the rotor to counter the imbalance. Typically the rotor is removed from the machine and delivered to a specialized shop with a balance pit or bunker to be balanced. Such maintenance is labor intensive and must generally be scheduled with the balance shop well in advance of the balance procedure. The logistics of transporting a large relatively delicate component also affects the cost and timeliness of an outage when the rotor is to be maintained. Additionally, the process of transporting the rotor carries inherent risks to the health and physical safety of the rotor. 
     SUMMARY 
     In one embodiment, a method of maintaining a machine using an in-situ vehicle (IV) includes transporting the IV from external to the machine into the gap, positioning the IV in the gap such that at least a portion of the IV circumscribes a work area of the work-piece, locking the IV between the work-piece and the interference body, and manipulating a tool coupled to the IV from external to the machine, the tool configured to transfer a component between the work-piece and a storage cassette on the IV. The IV may be used with a machine that includes a work-piece and an interference body positioned proximate a surface of the work-piece such that a relatively small gap extends between the work-piece and the interference body. 
     In another embodiment, an in-situ vehicle (IV) system for maintaining a machine includes a vehicle body positionable in the machine from external to the machine, a positioner coupled to the vehicle body and configured to position a storage cassette in x and y directions with respect to the vehicle body, and an insertion and removal tool storable within the vehicle body and extendable to a working position away from the vehicle body, the tool is configured to engage a component in the machine to couple and decouple the component from the machine. 
     In yet another embodiment, an in-situ vehicle (IV) system for balancing an electrical machine includes a vehicle body sized to traverse a gap between a rotor of the machine and a stator of the machine, a control panel coupled to the vehicle through an umbilical, a manipulator coupled to the vehicle body and configured to permit the vehicle body to be moved within the machine from external of the machine, and a shaft coupled to a tool onboard the vehicle wherein the shaft is configured to receive torsional input from a user to operate the tool. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective end view of a rotatable machine in accordance with an exemplary embodiment of the present invention; 
         FIG. 2  is a perspective view of an exemplary in-situ balance weight maintenance vehicle in accordance with an embodiment of the present invention; 
         FIG. 3  is a plan view of the vehicle shown in  FIG. 2 ; 
         FIG. 4  is an enlarged side elevation view of a portion of the vehicle with a weight maintenance tool extended to a working position; 
         FIG. 5  is another enlarged side elevation view of a portion of vehicle with the weight maintenance tool extended in an intermediate position between a storage position and the working position 
         FIG. 6  is an enlarged plan view of a portion of the vehicle looking radially outward from a surface; 
         FIG. 7  is a perspective view from below of head tool in accordance with an exemplary embodiment of the present invention; 
         FIG. 8  is an enlarged partially cut-away view of a gearbox body in accordance with an embodiment of the present invention; 
         FIG. 9  an enlarged partially cut-away side elevation view of the gearbox body in accordance with an embodiment of the present invention; 
         FIG. 10  is an enlarged plan view of a portion of the vehicle including a storage cassette; 
         FIG. 11  is a side elevation view of the cassette; and 
         FIG. 12  is a schematic block diagram of a control panel that may be used with the in-situ vehicle in accordance with an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description illustrates the disclosure by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the disclosure, describes several embodiments, adaptations, variations, alternatives, and uses of the disclosure, including what is presently believed to be the best mode of carrying out the disclosure. The disclosure is described as applied to a preferred embodiment, namely, a process of maintaining the internal components of a machine while the machine is substantially fully assembled or only partially disassembled. However, it is contemplated that this disclosure has general application to maintaining and inspecting various types of industrial and commercial devices having positions and components that may be difficult to access without significant disassembly. 
       FIG. 1  is a perspective end view of a rotatable machine  100  in accordance with an exemplary embodiment of the present invention. In the exemplary embodiment, rotatable machine  100  includes a stationary stator body  102  surrounding a core  104  interposed with a plurality of slots  106  for carrying stator windings about core  104 . End turns  108  may be used to join adjacent windings and/or join windings into electrical poles. Core  104  includes a radially inner circumferential surface  110  that defines a bore  112  therethrough. A rotor  114  is concentrically disposed within bore  112  and is rotatable about a longitudinal axis  116  extending into  FIG. 1 . Rotor  114  includes a coupling configured to permit a shaft  120  to be coupled to a prime mover (not shown) or exciter. Rotor  114  also includes a radially outer surface  122 . A gap  124  is defined between surface  110  and surface  122  that permits a flow of cooling gas, for example, air or hydrogen during operation. A plurality of baffles  126  may be positioned within gap  124  to direct gas flow into predetermined areas of gap  124  to facilitate cooling. In the exemplary embodiment, baffles  126  extend radially inwardly from stator body  102  into gap  124 . Rotor  114  also includes a plurality of inwardly radially directed holes  128  that are circumferentially spaced about surface  122  and extend into rotor  114  a distance  130 . Holes  128  are generally positioned about a full length (not shown in  FIG. 1 ) of rotor  114 . Holes  128  may be threaded or otherwise configured to receive one or more balance weights. End covers, a bearing, bearing lubricating system piping and/or field brush rigging which may be positioned proximate the end of generator  100  are not shown for clarity, however would be in place during the in-situ inspection described in more detail below. 
       FIG. 2  is a perspective view of an exemplary in-situ vehicle (IV)  200  in accordance with an embodiment of the present invention.  FIG. 3  is a plan view of vehicle  200  shown in  FIG. 2 . Vehicle  200  is configured to be slid into gap  124  and guided by an operator external to machine  100  into a position proximate one of holes  128 . In the exemplary embodiment, vehicle  200  is configured to be slid into machine  100  on a vertically upward side of rotor  114 . To this end, a hole  128  that contains weights that are to be removed or that to which weights will be added is positioned in a vertically upward position by rotating rotor  114  until the desired hole  128  is in the vertically upward position. Vehicle  200  includes a body  202  including a head member  204  and foot member  206  and a pair of channels  208  extending therebetween. A head-endlocking device  210  is coupled to head member  204  and a substantially similar foot-end locking device  212  is coupled to foot member  206 . Each locking device  210  and  212  includes a locking finger  214  and a locking actuator  216 . In the exemplary embodiment, locking actuator  216  is a pneumatic piston actuator, however a motor/leadscrew, an inflatable bladder, and other devices configured to lock vehicle  200  into a substantially fixed position between surface  110  and surface  122  are contemplated. A manipulator rod  218  is coupled to a distal end of head end locking device  210 . Manipulator rod  218  permits an operator external to machine  100  to manipulate vehicle  200  into position over the desired hole  128 . In an alternative embodiment, an electrical or pneumatic driven motor is coupled to a crawler assembly that is configured to transport vehicle  200  into position over desired hole  128 . 
     A positioning frame  220  is positionable in an X-direction and a Y-direction with respect to body  202 . Positioning frame  220  is slidable in each of the X-direction and Y-direction on respective sets of rails extending between head member  204  and foot member  206 , and extending between channels  208 , respectively. Specifically, positioning frame  220  is slidable in the X-direction along rails  222  extending between head member  204  and foot member  206  and in the Y-direction along rails  224  extending between channels  208 . Positioning frame  220  is driven in the X-direction by a first leadscrew assembly  226  and in the Y-direction by a second leadscrew assembly  228 . Positioning frame  220  includes a weight cassette  229  configured to store balance weights that are not currently being used, to receive weights that are being removed from desired hole  128 , and to hold weights that are being inserted into desired holes  128 . 
     Vehicle  200  also includes a weight maintenance tool  230  that is movable in a Z-direction from a storage position within body  202  to a working position radially displaced outwardly from desired hole  128 . A first video camera  232  is coupled to head member  204  with its field of view directed axially toward foot end and tilted radially inwardly towards the work area beneath tool  230  when in the working position. A second video camera  234  is coupled to tool  230  and its field of view is directed radially inwardly towards the work area. 
     Vehicle  200  is supplied with air for the pneumatic cylinders, electrical power for the leadscrew assembly motors and cameras, and video control and video signal pathways via an umbilical  236 . 
       FIG. 4  is an enlarged side elevation view of a portion of vehicle  200  with weight maintenance tool  230  extended to a working position.  FIG. 5  is another enlarged side elevation view of a portion of vehicle  200  with weight maintenance tool  230  extended in an intermediate position between a storage position and the working position. In the exemplary embodiment, tool  230  includes a power transmission device such as a gearbox body  402  movably coupled to positioning frame  220  through a plurality of pivotable linkages  404 . Gearbox body  402  is movable through an actuator assembly  406  operably coupled to positioning frame  220 . In the exemplary embodiment, actuator assembly  406  includes a pivot motor  408  and a pivot leadscrew  410 . Gearbox body  402  includes a radially inwardly directed tool head  412  that is retractable into gearbox body  402  in a storage or transport position  414  and extendable to a working position  416  (shown in broken lines  FIG. 4 ). Tool head  412  may include a plurality of different tools that are interchangeable and provide different capabilities for maintaining the balance weights of machine  100  or other components within machine  100  that are not easily accessible from external to machine  100 . In the exemplary embodiment, tool head  412  includes a flat head screwdriver head tool. In other embodiments, tool head  412  may include but is not limited to a hex head tool, a socket wrench tool, an adhesive or insulator application tool, and a cutting tool. In the exemplary embodiment, the flat head screwdriver head tool is powered by an operator manually through a rotatable shaft  418  having a grip end (not shown in  FIG. 4 ) distally located external to machine  100  and an opposing attachment end rotatably coupled to gearbox body  402 . Rotation of shaft  418  rotates tool head  412  such that balance weights that include threaded engagement portions may be threaded and unthreaded from threaded hole  128 . 
       FIG. 6  is an enlarged plan view of a portion of vehicle  200  looking radially outward from surface  122 .  FIG. 7  is a perspective view from below of head tool  412  in accordance with an exemplary embodiment of the present invention. In the exemplary embodiment, cassette  229  includes a rectangular body that is positionable with respect to tool head  412  to align one of a plurality of weight storage locations  602  with tool head  412 . During operation, for example, to remove a weight from hole  128 , head tool  412 , an empty weight storage location  602 , and hole  128  are aligned using positioning frame  220 . Camera  234  (shown in  FIG. 5 ) is used to display live video of the relative positions of head tool  412 , empty weight storage location  602  and hole  128 . Head tool  412  is extended to engage the weight in hole  128 . The operator applies a rotational force to shaft  418  using the grip end. The rotational force is transmitted through gearbox  402  to the head of the weight, which backs the weight out of hole  128 . The weight is sufficiently long to span the distance between surface  122  and cassette  229  such that before the threads on the weight completely disengage from hole  128  the threads have begun engagement of the threads in empty storage location  602  so that the weight is always thread-captured by the hole  128  or a storage location  602 . Such capture prevents the weight from falling into machine  100 , from where it would have to be retrieved. 
       FIG. 8  is an enlarged partially cut-away view of gearbox body  402  in accordance with an embodiment of the present invention. In the exemplary embodiment, gearbox body  402  includes a gear assembly  802  coupled in rotational engagement between shaft  418  and tool head  412  (not in view in  FIG. 8 ). In the exemplary embodiment, gear assembly  802  includes a pinion gear  804  coupled to an attachment end  806  of shaft  418 . Pinion gear  804  meshes with a bull gear  808  that is coupled to tool head  412 . As pinion gear  804  rotates bull gear  808  and tool head  412  are driven to rotate correspondingly. Because of the direct mechanical linkage between the threaded weight and the grip end  810  being manipulated by the user, the user receives feedback on the engagement of the threads of the weight with the threads of hole  128  by feel, thus minimizing the risk of cross threading. 
       FIG. 9  is an enlarged partially cut-away side elevation view of gearbox body  402  in accordance with an embodiment of the present invention. In the exemplary embodiment, tool head  412  includes a flat head screwdriver head tool  902  and is extended to a working position. In the exemplary embodiment, tool head is biased to the working position using for example, but not limited to a spring, pneumatic pressure inside tool head  412 , or gravity. Tool head  412  is retractable using a cable that is manually operated from external to machine  100 , a spring, and a vacuum pressure inside tool head  412 . In various embodiments, tool head  412  is mechanically latched in the fully extended, the fully retracted, or intermediate positions. 
       FIG. 10  is an enlarged plan view of a portion of vehicle  200  including cassette  229 .  FIG. 11  is a side elevation view of cassette  229 . In the exemplary embodiment, cassette  229  includes four storage locations  602 . In an alternative embodiment, any number of storage locations may be used. Also in the exemplary embodiment, each storage location  602  includes a threaded inner surface  1002  sized to engage a balance weight  1004 . Balance weight  1004  is threaded complementarily to threaded surface  1002 . 
       FIG. 12  is a schematic block diagram of a control panel  1202  that may be used with in-situ vehicle  200  in accordance with an exemplary embodiment of the present invention. In the exemplary embodiment, control panel  1202  includes a plurality of controls for operating in-situ vehicle  200 . Control panel  1202  includes a control  1204  for engaging locking fingers  214 , a control  1206  for moving positioning frame  220  along an X-direction, a control  1208  for moving positioning frame  220  along an Y-direction. Control panel  1202  includes a control  1212  for extending and retracting gearbox body  402  and a control  1214  for extending and/or retracting tool head  412 . Control panel  1202  further includes a camera control portion  1216  for adjusting video cameras  232  and  234  and a video monitor  1218 . Camera control portion  1216  may include but is not limited to a camera zoom, focus, tilt, and an illumination control. The controls may comprise electrical switches, rheostats, and valves for controlling pneumatically operated actuators. Umbilical  236  includes signal conduits such as but not limited to wires, fiber optics, and tubing that extend between control panel  1202  and vehicle  200 . Umbilical  236  is configured to transmit data from the vehicle body. In some embodiments, some of the signals are carried wirelessly between control panel  1202  and vehicle  200 . Pneumatic and electrical sources  1220  and  1222 , respectively, are coupled to control panel  1202  to power the components described above. 
     While embodiments of the disclosure have been described in terms of various specific embodiments, it will be recognized that the embodiments of the disclosure can be practiced with modification within the spirit and scope of the claims.