Abstract:
A lift system comprising an elongated rack and a roller pinion drive system. A preferred version has two parallel rack with plurality of rungs extending horizontally between the racks to form a ladder. A plurality of spaced apart mounting brackets are configured for affixing the ladder vertically to a stationary member, the stationary member not forming part of the invention. In this version, a drive unit retained within a carriage is mounted in proximity to the racks. The drive unit interacts with the racks to move the carriage upwardly and downwardly along the racks. A speed limiter is also disclosed that can be retained within the carriage below the drive unit and mounted in proximity to one of the racks. The speed limiter interacts with the rack to produce a breaking action if the drive unit fails, preventing the carriage to drop down quickly. Single rack and inclined rack versions are disclosed as alternatives.

Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    This invention relates generally to a lifting apparatus and specifically to a rack and roller pinion lift system. 
         [0003]    2. Prior Art 
         [0004]    Certain elevators apply a drive mechanism based on a rack and gear system, also referred to as rack and gear elevators. A motor mounted an elevator car drives a gear the teeth of which engage a wave crest type toothed rack (see  FIGS. 15-16 ) secured to a wall of an elevator shaft. Drawbacks of wave crest rack and gear elevators include noise generated when the gear teeth move along the rack and relatively poor ride comfort. For these reasons, rack and gear elevators are typically used in areas when noise and ride comfort are not critical such as the building industry or other industrial applications. For example, a dual rack and gear drive and an integral I-beam rail and rack system can be used in outdoor broadcast towers. 
         [0005]    Despite these drawbacks, a rack and gear elevator does not need a drive machine located in an overhead space or a machine room and does not need the expensive redundant pulleys and cables needed to assure backup safety typical of building elevators. However, a strong rack is needed, thus reducing cost savings. Further, a rack and gear elevator does not require a counterweight traveling along the elevator shaft and thus allows a smaller shaft or more passenger space in a given elevator shaft, but uses a large expensive gear and has to have a motor on the elevator carriage that may generate noise passengers would not like. Also the gear and rack engagement is adjacent the elevator and can generate additional noise passengers might not tolerate well in a typical office building. Such noise might accentuate any claustrophobia or other fears many people have of elevators. Rack and gear elevators, thus are not currently typically found in office buildings despite the clear advantage that they require less space than, for example, conventional traction elevators. For these reasons, rack and gear elevators are conventionally not considered suitable for non-industrial uses. I hope to change all that through improvements to both the rack and the gear using some out-of-the-box thinking. 
         [0006]    An first, preferred, exemplary embodiment provides a lift system comprising two elongated racks. A plurality of rungs extend horizontally between the racks to form a ladder with the racks parallel to each other, something that allows easier climbing and a ready attachment for safety equipment. A plurality of vertically spaced apart mounting brackets are provided for affixing the ladder vertically to a stationary object such as a wall, tower, pole or even tree A drive unit retained within a carriage is mounted in proximity to the racks. The drive unit interacts with the racks to move the carriage upwardly and downwardly along the racks. A speed limiter is retained within the carriage below the drive unit and mounted in proximity to one of the racks. The speed limiter interacts with the rack to produce a slow descent if the drive unit fails, preventing the carriage from dropping down too quickly for safety. Roller pinions are provided to smooth the action and minimize friction and provide mechanical advantage for easy operation with minimal power requirements. In an alternative exemplary embodiment, a single rack is used and the rack is inclined rather than completely vertical, so the system can be commercially embodied in a stairway chair lift. Other examples are also noted. 
         [0007]    The invention will be better understood by reference to the drawing and detailed description of exemplary embodiments. 
     
    
     
       DRAWINGS 
         [0008]    The drawing includes  16  illustrative figures in order to satisfy best mode, enablement and written description requirements, and two alternative embodiments are shown as examples. 
           [0009]    In this exemplary drawing: 
           [0010]      FIG. 1  is a right, upper front perspective view of a first exemplary rack and roller pinion lift system  100 ; 
           [0011]      FIG. 2  is a right side elevational view in partial cross section of system  100 ; 
           [0012]      FIG. 3  is a top view of system  100  with platform  122  removed; 
           [0013]      FIG. 4  is a front view of system  100  with carriage  101  removed to better show drive unit  200  and speed limiter  201 , 
           [0014]      FIG. 5  is a left upper rear perspective view of speed limiter  201 ; 
           [0015]      FIG. 6  is a lower left front perspective view of drive unit  200 ; 
           [0016]      FIG. 7  is a right side elevational view of pinion roller  205  and drive rack  103 ; 
           [0017]      FIG. 8  is a right side elevational view to show how roller  205  adapts to misalignment of upper rack  801  to lower rack  802 ; 
           [0018]      FIG. 9  is a left perspective view of rack  103 ; 
           [0019]      FIG. 10  is a right side elevational view of rack  103 ; 
           [0020]      FIG. 11  is a perspective view of an exemplary stairway chair lift  1100  with a single rack and roller pinion lift system  1101 ; 
           [0021]      FIG. 12  is a right side diagrammatic cross sectional view of a carriage  1102  of lift system  1101 ; 
           [0022]      FIG. 13  is a PRIOR ART right side elevational view of a roller pinion  1301  and rack  1302  for purposes of comparison with  FIG. 7 ; 
           [0023]      FIG. 14  is a PRIOR ART right side elevational view of roller  1301  and misaligned upper rack  1400  for purposes of comparison with  FIG. 8 ; 
           [0024]      FIG. 15  is a PRIOR ART left front perspective view of rack  1302  for purposes of comparison with  FIG. 9 ; and 
           [0025]      FIG. 16  is a PRIOR ART right side elevational view of rack  1302  for purposes of comparison with  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    First Exemplary Embodiment 
         [0027]      FIG. 1  is a right, upper front perspective view of a first exemplary rack and roller pinion lift system  100 . System  100  can be used for a deer stand or elevator or cargo lift or other vertical lifting applications. System  100  comprises a carriage  101 , a left rack  102 , and a right rack  103 . Carriage  101  consists of a rectangular boxlike housing  118  of a height  119  at least twice its width  120  or depth  121  with a right wall  115 , a front wall  116 , a left wall  117  (not shown but similar to right wall  115 ), an upper platform  122  and a floor  123 . In a passenger elevator, it will be understood that platform  122  would be the floor of the passenger compartment and floor  123  would be a subfloor spaced below to provide room for housing  118 . A right guide rail  104  is attached to a projects laterally outward from rack  103  and a left guide rail  105  projects laterally leftward and outward from rack  102 . A rung  106 , a rung  107 , a rung  108 , a rung  109  and several rungs (not shown) extend horizontally between rack  102  and rack  103  to form a ladder  110 . An upper mounting bracket  111  a lower mounting bracket  112  are provided to mount ladder  110  to a vertical surface such as a tree or wall (not shown). A right mounting hub  113  and left mounting hub  301  (see  FIG. 3 ) are provided for mounting a drive shaft  114  to carriage  101 . 
         [0028]      FIG. 2  is a right side elevational view in partial cross section of system  100 . Right wall  115  of carriage  101  is removed to better show a drive unit  200  and a speed limiter  201 . Drive unit  200  comprises a motor  202 , a gearbox or transmission  203 , horizontal drive shaft  114 , and a right roller pinion  205 . Speed limiter  201  comprises a roller pinion  206 , hydraulic pump  408  (see  FIG. 4 ) a restriction tube  208 , a first connector  207  and a second connector  210 . Tube  208  has a fluid flow constrictor  209 . Motor  202  has an electrical connector  410  (see  FIG. 4 ) for attachment to a source of electric power such as a battery (not shown). A guide roller  211  is disposed within rail  104 , and optionally also a guide roller  212 , a guide roller  213  and a guide roller  214  to assure engagement of pinion  205  and pinion  206  with rack  103 . 
         [0029]      FIG. 3  is a top view of system  100  with platform  122  removed to better show right roller pinion  205  and a left roller pinion  302 . A third roller pinion  206  (see  FIG. 2 ) is below pinion  205 . A mounting plate  306  is provided for attaching a hydraulic pump  408  (see  FIG. 4 ) to wall  115 . Roller pinion  302  comprises parallel vertical spaced right disc  303  and left disc  304  connected by a plurality of short rollers  305  Note that  FIGS. 2-5  show roller pinion  205  with twelve rollers  305  and  FIGS. 7 and 8  shows roller pinion  205  with only nine rollers  305 . The number of rollers  305  is explained below with reference to  FIGS. 7 and 8  below and is a significant departure from PRIOR ART roller pinion systems to reduce cost and power requirements for lift systems. A guide roller  211  is also disposed within rail  105 . 
         [0030]      FIG. 4  is a front view of system  100  with carriage  101  removed to better show drive unit  200  and speed limiter  201 . Tube  208  is attached to bottom cap  401  of motor  202  by a bracket  400 , A vertical mounting plate  403 , attached to transmission  203 , allows transmission  203  to be bolted to front wall  116 , whit butts (not shown) passing through notches  404 - 407  of plate  403 . Roller pinion  206  is attached to wall  115  by a hub  402 . Motor  202  contains an electrical connector  410  and speed limiter  201  contains an hydraulic pump  408 . 
         [0031]      FIG. 5  is a left upper rear perspective view of speed limiter  201 , to better show pump  408 , connector  210 , constrictor  209 , tube  208 , attachment band  504 , connector  505 , rollers  506 - 508 , right plate  509 , left plate  510  and shaft  511  retained to hub  402 . 
         [0032]      FIG. 6  is a lower left front perspective view of drive unit  200 ; 
         [0033]      FIG. 9  is a left perspective view of a small portion of rack  103  to better show rounded tooth  700  and horizontal flat upper surface  701 . Tooth  712  is similar with horizontal flat upper surface  715 . Likewise, tooth  702  has a horizontal flat upper surface  703 . Flat surface  703  provides better support for pinion roller  705  (see  FIG. 7 ) and less tendency for roller  705  to urge cage roller  205  outwardly off of rack  103  than prior art “wave crest” type racks such as rack  1302 . 
         [0034]      FIG. 10  is a right side elevational profile view of a portion of rack  103  to show the force balance on roller  705 . Just as surface  701  is horizontal, so is surface  715 . When roller  705  is in place resting on surface  715 , all the force it exerts on rack  103  is essentially downward in the direction of arrow  1000  and there is essentially no outward force  1001  of inward force  1002  except such as might be applied by right roller  205  (not shown) in which roller  705  is captured as previously described. This is in stark contrast to the prior art wave crest rack  1302 , which as seen in  FIG. 16  necessarily always applies an outward force in the direction of arrow  1600  tending to pull roller  1601  out of engagement. This is quite important when one realizes that roller  1601  will normally be free rotating. Added lateral restraints are needed and usually extra safety mechanisms for such a “wave crest” system. That makes for noisy clattering operation and tends to put added pressure on tip  1602 , which is pointed and not nearly as strong as the rounded design of tooth  700 . So, to fight that, multiple teeth are usually engaged (as seen in  FIG. 13 .) Engagement of multiple teeth (two, tooth  1303  and tooth  1304  are shown engaged in  FIG. 13  even though more might be needed) is used in prior art “wave crest” designs to spread the force to multiple tips (i.e. tip  1305  and  1306  rather than just tip  1305 ), since some play is required to account for minor misalignments, which play accentuates the tip breakage problem with the prior art systems. So, “wave crest” design makes for more failure due to breakage of teeth, which in turn requires a much thicker (horizontally) tooth such as seen by comparing  FIG. 15  and  FIG. 9 . When considering that a building elevator might require a pair of racks the full height of the building, this is no minor consideration. Racks are not cheap, but optimization can reduce that cost as I have done. Since tooth  700  is much more substantial in the vertical direction, strength is enhanced and tip breakage is much, much less likely so the rack can be quite thin. This is particularly true where the application is in the form of a dual rack ladder with rungs holding the racks in position. The ladder also gives a ready means of ascent for rescue and repair purposes. In short, system  100  is optimized for vertical applications and thus is a major breakthrough and advance in the art that should allow the advantages of roller pinion drive without the drawbacks. This is because rack  1302  is a “wave crest” type rack designed for horizontal not vertical orientations. In a horizontal orientation (envision  FIG. 16  rotated clockwise 90 degrees), all the weight of on roller  1601  would be applied toward the right in  FIG. 16 , thus forcing roller  1601  into engagement with rack  1302 . But when rack  1302 , designed for horizontal use, is rotated vertical it is dysfunctional for roller pinions. Now, if instead of roller  1601  a gear (not shown) with teeth matching the teeth of rack  1302 , the tendency remains. 
         [0035]    Operation of First Exemplary Embodiment 
         [0036]      FIG. 7  is a right side elevational view of roller pinion  205  and drive rack  103 . To show operation rack  103  contains a rounded tooth  700  with horizontal upper surface  701 , rounded tooth  702  with horizontal upper surface  703 , while load bearing roller  705  on surface  703  in recess  710 , exiting roller  706  rises from surface  704  exiting recess  709 , and entering roller  707  contacts tooth  712  at point  713  and rolls easily into recess  711  to continue process by supporting load as roller  705  exits recess  710  and roller  708  contacts tooth  700  and rolls onto surface  701  of recess  714 . One roller bears the weight so that the other rollers can easily enter and leave under less weight. 
         [0037]      FIG. 8  is a right side elevational view to show how roller  205  adapts to misalignment of upper rack  801  to lower rack  802 . As with  FIG. 7  described is tooth  804 , upper surface  805 , upper surface  806 , upper surface  807 , entrance point  808  for roller  811  into recess  815  while roller  812  on surface  806  is in misaligned recess  816 , as roller  810  leaves surface  809 , with roller  813  next up and set to enter recess  814  to rest on surface  805   
         [0038]      FIG. 13  is a PRIOR ART right side elevational view of a wave crest type similar to that shown in US Patent No. roller pinion system  1300 . Roller pinion  1301  and rack  1302  are shown for purposes of comparison with  FIG. 7 . Note large disc size with multiple rollers contact and load always on a slope. System  1300  is designed for horizontal application, not vertical. In contrast we provide a transverse surface with a rounded tooth so we have a much smaller roller pinion  205 , fewer rollers, much stronger rollers, much stronger teeth, more rounded teeth, so rack  103  can be thinner. 
         [0039]      FIG. 14  is a PRIOR ART right side elevational view of roller pinion  1301 , misaligned rack  1400  and rack  1401  for purposes of comparison with  FIG. 8 . Note pressure on thin tips of sharp teeth leading to breakage of tips and inability to climb. 
         [0040]      FIG. 15  is a left front perspective view of rack  1302  for purposes of comparison with  FIG. 9 , Rack  1302  has to be much thicker to handle load due to thin wave crests. 
         [0041]      FIG. 16  is a right side elevational view of rack  1302  for purposes of comparison with  FIG. 10   
         [0042]    Alternative Embodiment 
         [0043]      FIG. 11  and  FIG. 12  show an alternate embodiment as exemplary of a single inclined system  1101 . With system  1101  a single rack, single drive roller and a non-vertical system oriented at an incline for a stairway chair lift application is seen as within the scope of the invention. The system retains much of the advantage of the vertical system due to the rack configuration. 
         [0044]      FIG. 11  is a perspective view of an exemplary stairway chair lift  1100 , with a single rack and roller pinion lift system  1101  having a carriage  1102 . 
         [0045]      FIG. 12  is a right side diagrammatic cross sectional view of carriage  1102  of lift system  1100  having a housing  1200  covering and roller pinion  1201 . System  1100  comprises a rack  1203  with an upper surface  1207  and a lower surface  1208  mounted by a bracket  1210  to a stairway  1209 . An upper front guide roller  1202 , an upper rear guide roller  1205 , a lower front guide roller  1204  and a lower rear guide roller  1206  are provided. 
         [0046]    Conclusion, Considerations, and Coverage 
         [0047]    Accordingly the reader will see that, according to the invention, I have provided a lift system that does not require as much power as convention lift systems, whether vertical or inclined or horizontal and allows reduced rack thickness due to racks with relatively flat upper surfaces and much larger teeth, This also allows reduced roller pinion size and allows better handling of misalignments, For example it has been found that a standard 18 V rechargeable power drill can operate a deer stand using this system. 
         [0048]    While the above description contains many specifics, these are not limitations on the scope of the invention, but rather exemplifications of the various embodiments thereof. Many other embodiments are possible within the teachings of the invention. For example,  FIG. 1  could be easily adapted to elevator applications using either single or dual or multiple racks, funiculars of any size or weight or width, stairway chair lifts, vertical or inclined boat launchers or lifts, vertical of inclined cargo lifts, exterior building lifts, construction elevators and lifts, window washing lifts, all with reduced power requirements. 
         [0049]    Thus coverage in the claims below should be determined by the claims and their legal equivalents, and not limited to the examples given.