Abstract:
A flexible lance drive device has at least one drive motor in a first portion of a housing and a drive axle projecting across a second portion of the housing carrying a cylindrical spline drive roller. A plurality of cylindrical guide rollers on fixed axles span across the second portion of the housing aligned parallel to the spline drive roller. An endless belt wrapped around the at least one spline drive roller and guide rollers has a generally smooth outer surface and a transverse splined inner surface having splines shaped complementary to splines on the spline drive roller. A bias member supports a plurality of follower rollers each aligned vertically above one of the at least one spline drive roller and guide rollers operable to press each follower roller toward one of rollers to frictionally grip a flexible lance hose when sandwiched between the follower rollers and the endless belt.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/332,309, filed May 5, 2016, entitled Endless Belt Flexible Tube Cleaning Lance Drive Apparatus, the content of which is incorporated by reference herein in its entirety. 
     
    
     BACKGROUND OF THE DISCLOSURE 
       [0002]    The present disclosure is directed to high pressure fluid cleaning lance handling systems. In particular, embodiments of the present disclosure are directed to an apparatus for advancing and retracting one or more flexible tube cleaning lances from tubes arranged in an array, such as in a heat exchanger, from a position adjacent a heat exchanger tube sheet. 
         [0003]    A flexible lance drive apparatus typically includes a drive motor coupled via gearing, a chain, or a belt to one or more drive mechanisms. Drive mechanisms can be rollers that are arranged in pairs or sets sandwiching a flexible lance hose therebetween or chain and block assemblies oriented with interlocking top and bottom assemblies. At least one roller of the sets of rollers, or chain and block assemblies may be driven. In order to accommodate different diameter lance hoses, the rollers or chain and block assemblies must be laboriously disassembled and replaced, and it may be necessary to modify the drive motor as well to accommodate the characteristics of a different driven lance hose. Additionally, once a mechanism has been properly configured for a given lance hose size, the distance between opposing drive mechanism roller pairs as the force that a given pair exerts on a lance hose is typically adjusted via a manual mechanical adjustment. 
         [0004]    U.S. Pat. No. 9,070,830, for example, teaches a drive apparatus which requires the lance itself to be bent around a portion of the drive wheel in order to ensure sufficient drive force is transferred to the lance itself, especially in real world environmental application scenarios which are often less than ideal. Furthermore, such drive apparatuses are large, bulky, and thus must be either separately located on a floor near the heat exchanger tube sheet into which the lance or lances are supposed to be guided, as is shown in that publication, or rigidly mounted to a tray spaced from and aligned with the tube sheet. In such cases the tube bundle is typically physically removed from the heat exchanger and placed in an environment with sufficient space to accommodate the tray and drive assembly. 
         [0005]    A lance drive mechanism incorporating a pair of opposing endless belts is disclosed in US Patent Application Publication 2010/0300498. This apparatus includes two opposing, segmented, endless belts above and below a flexible lance. Each of the belts has a V shaped groove in which the lance being driven resides. A pair of opposing platform clamps are used to push the endless belts against the lance(s) in the V shaped grooves of the belt. This generates a substantial drag on the endless belt that must be overcome by the power of the drive motor or motors. 
         [0006]    What is therefore needed is a compact package drive solution that takes up a minimal space, can be mounted directly to an x-y lance positioner, facilitates simplified handling of multiple lances and several different sized flexible lance hoses interchangeably, can operate consistently under a variety of operating conditions, can be optimized for performance remotely, and remains simple to repair, service and modify for a variety of applications. 
       SUMMARY OF THE DISCLOSURE 
       [0007]    A flexible lance drive apparatus or device in accordance with the present disclosure directly addresses such needs. An exemplary embodiment of a flexible lance drive apparatus includes a housing, at least one pneumatic drive motor disposed in a first portion of the housing having a drive axle projecting across a second portion of the housing carrying a cylindrical spline drive roller, a plurality of cylindrical guide rollers on fixed axles spanning across the second portion of the housing aligned parallel to the spline drive roller, a side surface of each guide roller and the at least one spline drive roller being tangent to a common plane between the rollers, and an endless belt wrapped around the at least one spline drive roller and guide rollers. The belt has a generally smooth outer surface and a transverse splined inner surface having splines shaped complementary to splines on the spline drive roller. A bias member supports a plurality of follower rollers each aligned vertically above one of the at least one spline drive roller and guide rollers. The bias member is operable to press each follower roller toward one of the spline drive rollers and guide rollers to frictionally grip a flexible lance hose when sandwiched between the follower rollers and the endless belt. 
         [0008]    An exemplary embodiment of a flexible lance drive apparatus in accordance with the present disclosure includes a generally rectangular housing and a first and a second drive motor disposed side by side and spaced apart in a first portion of the housing. Each drive motor has a drive axle projecting into a second portion of the housing carrying a cylindrical spline drive roller. A plurality of cylindrical guide rollers on fixed axles span across the second portion of the housing between the spline drive rollers and are aligned parallel to the spline rollers. An endless belt having an inner spline side and an outer side is wrapped over the drive rollers and guide rollers. The side surface of each guide roller is tangent to an axis tangent to and extending between the spline rollers. A bias member supporting a plurality of follower rollers is aligned vertically above the spline drive rollers and guide rollers. This bias member is operable to presses each follower roller against a flexible lance hose sandwiched between the follower rollers and the endless belt on the spline rollers as the endless belt is rotated to frictionally propel the lance hose forward and backward through the apparatus. 
         [0009]    Further features, advantages and characteristics of the embodiments of this disclosure will be apparent from reading the following detailed description when taken in conjunction with the drawing figures. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a belt side view of the drive apparatus in accordance with the present disclosure. 
           [0011]      FIG. 2  is a drive motor side view of the drive apparatus in accordance with the present disclosure. 
           [0012]      FIG. 3  is a belt side perspective view of the drive apparatus in accordance with the present disclosure with its side cover removed. 
           [0013]      FIG. 4  is a belt side perspective view as in  FIG. 3  with the upper and lower vertical support plates removed. 
           [0014]      FIG. 5  is a drive motor side perspective view of the drive apparatus shown in  FIGS. 1 and 2  with the housing top plate, bottom plate, and end plates removed and the first vertical support plate shown transparent. 
           [0015]      FIG. 6  is a vertical sectional view taken along the line  6 - 6  through the apparatus shown in  FIG. 1 . 
           [0016]      FIG. 7  is a vertical sectional view taken along the line  7 - 7  through the apparatus shown in  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0017]    An exemplary high pressure cleaning lance hose drive apparatus according to the present disclosure is shown in  FIGS. 1-7 . Referring now to  FIG. 1 , a belt side view of the apparatus  100  is shown with its side cover removed. The apparatus  100  has a rectangular box housing  102  that includes a flat top plate  104 , a bottom plate  106 , front and rear walls  108  and  110 , and two C shaped carry handles  112 , one on each of the front and rear walls  108  and  110 . In  FIGS. 1-7 , sheet side covers (not shown) are removed so that internal components of the apparatus  100  are visible. 
         [0018]    Fastened to the front wall  108  is an exit hose guide manifold  114 . Fastened to the rear wall  110  below the carry handle  112  is a hose entrance guide manifold  116 . Each of these manifolds  114  and  116  includes a set of hose guide collets  118  for guiding one to three flexible lance hoses (not shown) into and out of the housing  102 . Each guide collet set  118  is sized to accommodate a particular lance hose diameter. Hence the collet sets are changeable depending on the lance size to be driven by the apparatus  100 . 
         [0019]    A motor side view of the apparatus  100  is shown in  FIG. 2 . The housing  102  includes an inner vertical support partition wall  120  fastened to the front and rear walls  108  and  110  and the top and bottom plates  104  and  106 . This vertical support partition wall  120  divides the housing into a first portion and a second portion. The first portion houses hose fittings and drive motors. The second portion is a belt cavity  121  through which flexible lance hoses are driven, and is shown at least in  FIGS. 1, 3 and 4 . 
         [0020]    In this exemplary embodiment  100 , the inner vertical support wall  120  carries a pair of pneumatic drive motors  122  and  124  mounted such that their drive shafts  126  and  128  protrude laterally through the support wall  120  into the second portion, or belt cavity, between the inner vertical wall  120  and an outer vertical lower support wall  130 , shown in  FIGS. 1 and 3 . Each of the drive motors  122  and  124  is connected to pneumatic forward feed line  132  and reverse feed line  134  through a feed manifold  136  fastened to the top plate  104 . A clamp pressure feed line fitting  138  also passes through this feed manifold  136  to a hose clamp assembly  144  described below. Each of the drive motors  122  and  124  is preferably a compact radial piston pneumatic motor. However, hydraulic or electric motors could alternatively be used. 
         [0021]    On the belt side view shown in  FIGS. 1 and 3 , the belt cavity  121  is defined between the inner vertical wall  120  and the outer lower support wall  130 . A separate upper outer support wall  140  aligned with the lower outer support wall  130  provides a rigid joint between the front and rear walls  108  and  110  while providing a visible space between the entrance and exit guide manifolds  116  and  114 . This spacing helps an operator thread up to three lances laterally into and through the belt cavity  121  between an endless drive belt  142  and a vertically arranged hose clamp assembly  144 . Each of the support walls  120 ,  130  and  140  is preferable a flat plate of a lightweight material such as aluminum or could be made of a structural polymer with sufficient strength and rigidity to handle the motor operational stresses involved. 
         [0022]    A perspective view of the apparatus  100  with the upper and lower outer vertical support walls  140  and  130  removed is shown in  FIG. 4 . Each of the motor drive shafts  126  and  128  has an axial keyway fitted with a complementary key (not shown) that engages a corresponding keyway in a cylindrical splined drive roller  146 . Thus each drive roller  146  is slipped onto and keyed to the drive shaft so as to rotate with the drive shaft  126  or  128 . Each splined drive roller  146  has its outer cylindrical surface covered with equally spaced splines extending parallel to a central axis of the roller  146 . The distal ends of each of the drive shafts  126  and  128  extends through the lower outer support wall  130  and are primarily laterally supported from plate  120 . Additional lateral support for the distal ends of each of the drive shafts  126  and  128  is provided by the lower outer support wall  130  via cone point set screws engaging a V groove (not shown) in each of the shafts  126  and  128 . 
         [0023]    Each of the drive shafts  126  and  128  may extend fully through the splined drive rollers  146  or the drive motors  122  and  124  may each be fitted with a stub drive shaft which fits into a bearing within the proximal end of each of the splined drive rollers  146 . A separate bearing supported drive shaft  126  or  128  extends out of the distal end of each drive roller  146  and is fastened to the support wall  130  via cone point set screws. In such an alternative, the drive rollers  146  become part of the drive shafts  126  and  128 . 
         [0024]    Spaced between the two splined drive rollers  146  is a set of four cylindrical guide rollers  148  that are supported by the lower outer support wall  130  via a vertical plate  150  and a pair of rectangular vertical spacer blocks  152  that are through bolted to both the lower outer support wall  130  and inner vertical wall  120  through the vertical plate  150  via bolts  154 . This preferred bolting arrangement is shown in the sectional view of  FIG. 7 . While the bolts  154  pass through the vertical plate  150 , their distal ends extend further through, and are threaded into holes  156  through the inner vertical wall  120 . 
         [0025]    Tension on the endless belt  142  is preferably provided by a tensioner roller  158  between the spacer blocks  152  that is supported from the inner vertical plate  150  on an eccentric shaft  160 , and accessed through an opening  162  in the inner vertical wall  120 , shown in  FIG. 2 . Rotation of this eccentric shaft  160  essentially moves the tensioner roller  158  through a slight arc downward or upward to provide more or less tension on the belt  142 . 
         [0026]    To replace the belt  142 , the four bolts  154  are loosened and screws holding the outer lower wall  130  to the front and rear walls  108  and  110  are removed. The cone point set screws engaging a V groove (not shown) in each of the shafts  126  and  128  are then removed. The assembled structure including the vertical plate  150 , spacer blocks  152 , belt  142 , drive rollers  146 , and guide rollers  148  can then be removed as a unit by sliding the drive rollers  146  off of the keyed shafts  126  and  128 . 
         [0027]    In an alternative configuration if the bolts  154  are instead threaded into the plate  150  rather than the wall  120 , and simply guided through holes  156  in wall  120 , the outer lower wall  130 , inner vertical plate  150 , tensioner roller  158  on eccentric shaft  160  and spacer blocks  152  can form a unitary assembly  164  carrying the guide rollers  148  that can be separately removed laterally from the belt cavity as a unit by unfastening the outer lower wall  130  from the front and rear walls  108  and  110  and removing set screws from the drive rollers  146 . When this unitary assembly  164  is removed, only the belt  142  and drive rollers  146  on shafts  126  and  128  remain in the belt cavity. The endless belt  142  may then be slipped easily off of the drive rollers  146  and a new belt  142  installed. 
         [0028]    The assembly  164  including outer lower wall  130 , inner vertical plate  150 , tensioner roller  158  and spacer blocks  152  is then reinstalled between the end walls  108  and  110 . The distal ends of the bolts  154  guide reassembly by registering with holes  156  in the inner vertical wall  120 . The tensioner roller  158  may then be readjusted to provide proper belt tension through the opening  162  through the inner vertical wall  120 . 
         [0029]    Each of the splined drive rollers  146  preferably has equally spaced alternating spline ridges and grooves around its outer surface which are rounded at transition corners so as to facilitate engagement of the complementary shaped lateral spline ridges and grooves in the inner side or surface of the endless belt  142 . Elimination of sharp transitions at both ridge corners and groove corners lengthens belt life while ensuring proper grip between the rollers and the belt. The outer surface portion or cover of the endless belt  142  is preferably flat and smooth to prevent undesirable hose abrasion and degradation and is preferably formed of a suitable friction material such as polyurethane. The inner side portion of the belt  142  is preferably a harder durometer polyurethane material bonded to the outer side cover. For applications with significant hydrocarbons or high lubricity products, grooves machined across the cover at 90° to the direction of belt travel may be utilized for improved traction performance against the flexible lance hose. 
         [0030]    Spaced above the belt  142  in the belt cavity is a lance hose clamp assembly  144  including an idler roller assembly  170 . This exemplary clamp assembly  144  includes a multi-cylinder frame  172  fastened to the top plate  104  of the housing  102 . The multi-cylinder frame  172  carries two or three single acting pneumatic cylinders with pistons  174  that are each connected to a carrier block  176  and connected together via a pair of parallel spaced idler carrier frame rails  178 . A set of six idler rollers  180  is carried by the frame rails  178 , each vertically positioned directly above either one of the drive rollers  142  or one of the guide rollers  148 . Each piston  174  may be spring biased such that without pneumatic pressure, the pistons  174  are all withdrawn or retracted fully into the multi-cylinder frame  172  so as to provide access space between the idler rollers  180  and the drive belt  142  for insertion and removal of flexible lance hoses. 
         [0031]    The idler rollers  180  are best shown in the sectional views through the apparatus  100  shown in  FIGS. 6 and 7 . Each idler roller  180  is a bearing supported cylindrical body, preferably of aluminum, having three spaced annular grooves  182  each preferably sized complementary to the anticipated lance hose size. These annular grooves may be V shaped, semicircular, partial trapezoidal, rectangular, or smooth U shaped so as to provide a guide through the apparatus  100  and keep the flexible lance in desired contact with the endless belt  142  during transit. Preferably the idler rollers  180  are made of aluminum or other lightweight material capable of withstanding bending loads and each groove has a concave arcuate, preferably semicircular cross sectional shape. Each groove may alternatively be a rectangular slot with corners having a radius profile to allow the hoses to have limited lateral movement as they are fed through the apparatus  100 . 
         [0032]    In use, the drive apparatus  100  may be utilized with one, two, or three flexible lances simultaneously. In the case of driving one lance, such a lance would be preferably fed through the center collet and beneath the center groove of the idler rollers  180 . When two lances are to be driven, the inner and outer collets  118  would be used. If three lances are to be driven, one would be fed through each collet and corresponding groove of each idler roller  180 . 
         [0033]    In alternative embodiments, more than three lance drive paths may be provided such as 2, 4 or five. Electrical or hydraulic actuators and motors may be used in place of the pneumatic motors shown and described. Although a toothed or spline endless belt is preferred as described and shown above, alternatively a smooth belt or grooved belt with wider spline spacing could be substituted along with appropriately configured drive rollers. The guide rollers  148  are shown as being smooth cylindrical rollers. They may alternatively be splined rollers similar to the drive rollers  146 . 
         [0034]    The control system for pneumatic air supplied to the drive motors  122  and  124  may also include an autostroke function that senses reductions in air flow to each of the drive motors during forward operation, which are indicative of increased resistance to lance movement, and automatically stops, reverses and reapplies forward direction air pressure to the motors to repetitively stop, withdraw and re-advance the flexible lances in the event obstacles or restrictions are encountered and sensed within tubes being cleaned. 
         [0035]    Many variations may be made to the apparatus  100 . For example, the lower support wall  130  may alternatively be reduced in overall size such that the belt  142  may be easily removed over the support wall  130 . In this case, the entire belt drive assembly will be cantilever supported entirely from the inner support wall  120  via spacer blocks  150  and the motor shafts  126  and  128 . In such an alternative configuration, one or more support blocks (not shown) may be provided on the belt side access door (not shown) to provide added vertical support to the reduced size alternative support wall  130  when the access door is closed as during drive operation. In another variation, where additional traction is desired, a longer space between the drive rollers  146  and an increased number of guide and idler rollers may be provided. In the embodiment  100  shown there are four idler/guide roller sets. For greater traction applications, 5, 6 or 7 idler/guide roller sets may be utilized in such an embodiment along with longer drive belts. 
         [0036]    The single piece top idler rollers  180  may be replaced with a series of three separate grooved idler rollers bearing supported on each of the idler axle shafts to reduce friction and allow relative motion between flex lances which can simplify synchronization of the set of 2 or 3 lances at the fully extended position and at the fully retracted position of the lances. Finally, polymer or composite materials may be substituted in place of metal components in the embodiments shown, as these embodiments are merely exemplary. Therefore, all such changes, alternatives and equivalents in accordance with the features and benefits described herein, are within the scope of the present disclosure. Such changes and alternatives may be introduced without departing from the spirit and broad scope of this disclosure as defined by the claims below and their equivalents.