Patent Application
20080087112
The miniature air gap inspection crawler 1 illustrated in a simplified form and in perspective in
The tracks 10 may include a flexible material and extend around the outside of the drive modules 2, 3 and 4 as shown. The inner sides of the tracks 10 may have teeth that engage teeth on the surface of the drive wheels and the idler wheels of the drive modules. The center drive module 2 and its track 10 are wider than the side drive modules 3 and 4 and their tracks 10. The wider center drive module track prevents the wide track 10 from dropping into a stator slot.
A drive module construction, with reference to the center drive module 2, includes a base plate 11 and side plates 22 secured to the base plate by bolts 30. Other attachment means may be used as one skilled in the art would appreciate. The base plate 11 includes a pocket, beneath 12, and a bore 13 for receiving the drive motor module 12, the motor 14, the drive shaft 15 and the bearing 16. The drive shaft 15 may be a unitary element or may include a shaft coupled to the motor output shaft in a conventional manner. A drive gear of a bevel gear assembly 17 is secured at the end of the drive shaft 15 in a driving relation to a bevel gear of the gear assembly 17 secured on the drive wheel shaft 19. The shaft 19 is mounted at its ends in a number of bearings 20 secured in forward side plates 23 that are integral extensions of the side plates 22. The two drive wheels 18 are mounted on the shaft 19 with the bevel gear assembly 17 in between. The drive wheels contain teeth on the circumferential surface for engaging the teeth on the underside of the track 10. At the rearward end of the drive module 2, an idler wheel 25 is supported on a shaft 26 held in a number of bearings 27 mounted in a number of slidable bearing blocks 28. The bearing blocks 28 are held in slots in a number of rear side plates 24 that are integral with the side plates 22. An adjustment screw 29 is used for sliding a bearing block 28 forwardly or rearwardly to provide for adjusting the location of the idler wheel 25 with respect to the base plate 11 and thus the tension on the track 10. An idler wheel 25 has a toothed surface as illustrated.
The side drive modules 3 and 4 are similar in construction to that of the center drive module 2 but differ in that they are not as wide and have only partial interior side plates, a plate 34 at the forward end and a plate 35 at the rearward end. In addition, the side drive modules 3 and 4 have pivot shafts 33 secured to the base plate 11 and side plates 32, and providing a pivot support for the pneumatic ram 6. The side plates 32 may include a single plate as shown. The idler wheel 25 is also adjustable by means of a number of screws 29 to provide for adjusting the tension on the track 10.
The two side drive modules 3 and 4 are secured at the interior side to the main yoke 8. In particular, the base plate 11 is secured to a yoke arm 37 by a bolt 38 and a forward side plate 34 is secured to the main yoke 8 by another bolt 38. A number of screws 36 in the main yoke 8 are for securing the inspection module yoke 60, illustrated in
The pneumatic rams 6 and the link arms 7 are assembled between the center drive module 2 and the side drive modules 3 and 4 in a manner that permits the center drive module 2 to be raised with respect to the side drive modules 3 and 4. Each link arm 7 includes a pin flange 45 and a clamping plate 46. The link arms 7, of the configuration illustrated, are secured to the center drive module side plates 22 by means of screws 50 in a manner that allows a link arm to pivot on the screw. At the forward end of the link arms 7, clamp plates and clamping bolts 43 clamp the link arms to the cross shaft 9. The ends of the cross shaft 9 are disposed in bores of yoke arms 37 in a manner that permits the cross shaft 9 to rotate. Clamping the link arms 7 to the cross shaft 9 ensures that the center drive module 2 is kept from becoming skewed while being raised to the elevated position. A piston rod 47 of the pneumatic ram 6 is connected to the link pin 44 of the link arm 7 by a coupling 48. A link pin 44 is secured between the link arm 7 and the pin flange 45.
The inspection module 5, as shown in
The pneumatic rams 6 are of the spring return type and are operated by air supplied through pneumatic lines (not shown) attached to an air inlet port 49 shown in
Each of the motors 14 in the drive modules is a reversible servo motor individually controlled at a computer control console. The motors have the capability of driving the crawler at speeds of up to about 30 inches per minute. The speed of each motor 14 is controlled through a motion control program at the computer console.
To ensure accurate tracking in an axial run where the crawler 1 travels in the axial direction along the air gap of a generator, the crawler 1 is expanded and the center drive module 2 is in contact with the stator core and is driven at the same speed and in the opposite rotational direction to the side drive modules 3 and 4. When the crawler 1 is running in a circumferential direction, the crawler 1 is expanded and the center drive module 2 is in contact with the stator core and is driven slightly faster and in the opposite rotational direction to the side drive modules 3 and 4 in contact with the field in order to compensate for the greater diameter of the stator core. In order to turn the crawler 1, the speed between the left and the right side drive modules 3 and 4 is varied by driving the two modules at the same speed but in opposite directions that causes the crawler 1 to pivot about the contact point of the center core-contacting module. While the field side drive module tracks 10 are turning in opposite directions to turn the expanded crawler 10, the center core-contacting module track 10 can be oscillated forward and backward to reduce friction in making the turn.
As clearly illustrated in
The camera 56 may be a high resolution, ⅓ inch, color CCD forward view camera with a field of view of approximately 50 degrees and a fixed focus for straight ahead viewing. The camera 56 is used both for navigating the crawler 1 through an air gap and making inspections. The camera 59 is a side view camera with the prism 58 that rotates 360 degrees and is primarily used for detailed inspection of the stator core, generator field and retaining ring faces. The camera 59 has a remotely controlled power focus and, in the preferred embodiment, is a high resolution, ⅓ inch, color CCD camera with a field of view of approximately 30 degrees. Rotation of the prism 58 and the focus of the camera 59 are by remote control of the motors 57 and 70, respectively, at the computer control console.
Prior to performing an inspection, the crawler 1 is compressed to its collapsed position as illustrated by the solid lines in
An umbilical, which includes electrical cables, pneumatic lines and a tether line, is attached to the crawler. The electrical lines are connected to a computerized motion control system for control of the crawler 1 as one skilled in the art of motion control understands.
The crawler 1 in its collapsed position is inserted in a generator air gap at the 12 o'clock position and driven in a largely axial direction to a desired location, using the view from camera 56 as a navigation aid. Upon reaching a desired location in the air gap, the crawler 1 is expanded by supplying air through the attached air lines to the pneumatic rams 6. The spring return pneumatic rams 6 are of the same construction as the ram 64. The computer motion control system is used by an inspector to drive the crawler 1 to the necessary inspection points while the supply of air to the pneumatic ram 64 through an attached air line can be controlled to achieve a desired tilt of the inspection module 5.
The crawler 1 is normally retrieved from the generator air gap by driving it out. However, in the event of a motor failure, power failure or other situation that causes the crawler 1 to become immobile, the crawler 1 can easily be retrieved manually. Air pressure to the spring return pneumatic rams 6 is released and after the crawler 1 collapses to its collapsed position it is pulled out by the tether line.
The miniature air gap inspection crawler 1 permits inspection of the generator field and stator core with minimal disassembly of the generator, single ended entry into the generator and no rotation of the generator field. The views provided by the cameras allow a trained inspector to determine easily the maintenance procedures that need to be instituted and can be used to provide a history of the generator.
A further embodiment, a crawler 100, is shown in
The crawler 100 also may have the cameras 56, 59 or similar types of camera modules positioned thereon. The cameras may be any conventional type of video device. Other types of monitoring or detection devices also may be mounted onto the crawler 100.
In use, the crawler 100 may be positioned within the radial air gap for introduction to the field as is described above. The crawler 100 thus has full access to all areas of the field. The crawler 100 can be maneuvered in any desired pattern so as to provide ultrasonic and other types of inspections. Alternatively, the crawler 100 may be maneuvered directly to an area of suspected damage.
It should be apparent that the foregoing relates only to the preferred embodiments of the present invention and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.
