Abstract:
A apparatus includes an arm, a housing having a chamber, a vane rotatably movable within the chamber and an engaging member. The engaging member is slidingly coupled to the arm. The engaging member is selectively positionable in an engaged and a disengaged position with the vane such that the arm rotates in response to rotation of the vane when the engaging member is in the engaged position.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates generally to powered positioning devices and, more particularly, to a powered pivot unit for moving or positioning industrial tooling. 
     Pivot units are commonly used in industrial applications for positioning tooling or work pieces during forming and machining operations. The previously known devices include a pneumatically or hydraulically actuated linear piston cylinder which causes one or more arms to move through a desired range of rotational motion to position the tool or work piece. These devices are often large clamps equipped with a toggle mechanism to achieve the rotational motion of the tool mount. Unfortunately, the toggle mechanism exhibits a torque per rotation angle curve which is not linear. Because the tooling or components to be rotated may weight 100 pounds or more and are often mounted 48 inches from the pivot point, existing pivot units may be unable to lift the tool. 
     Many conventional pivot units use a linear fluid cylinder coupled to the linkage to provide the lifting force. The conventional pivot units have cylinders separately attached to a body. The stroke of the fluid cylinder is directly proportional to the amount of rotation available at the tool mounting end. In an attempt to conserve the amount of actuating fluid required, existing manufacturers provide families of power pivot units equipped with a variety of differently sized cylinders. Long cylinders are used if large rotation angles are desired. Large diameter cylinders are used to lift heavy loads. Therefore, an undesirably large number of assemblies must be maintained in inventory to provide manufacturing flexibility. The use of elongated fluid cylinders also creates a relatively large and unwieldly pivot unit assembly which requires extra space in the end use manufacturing plant. Also, service of the linkage or toggle mechanism requires that the tool holding portion be disassembled. 
     In accordance with the teachings of the present invention, a preferred embodiment of a powered pivot unit includes a rotary actuator which provides a generally constant torque output over the entire operating range of pivot angles. In another aspect of the present invention, the rotary actuator includes a rotary vane which is positioned on an opposite side of the pivot point relative to the rotating arm assembly. This effectively counter-balances the tooling to reduce the torque required to lift or position the tool. A further aspect of the present invention provides 105 degrees of available rotation from a single rotary actuator. Because the powered pivot unit of the present invention utilizes a rotary vane within an arcuate chamber, less pressurized fluid is required to obtain the full 105 degrees of rotation when compared to linear fluid cylinders. 
     Yet another aspect of the present invention includes integral stops, shocks and switch assemblies which are adjustable in generally 15 degree increments throughout the full 105 degree range of rotation. In still another aspect of the present invention, a lock is provided at each 15 degree position to maintain the position of the tool when service is required. 
     Yet another aspect of the present invention is directed to ease of serviceability. Specifically, the actuator assembly may be replaced as a cartridge without disturbing the tool-to-arm assembly interface nor the pivot unit-to-bench interface. Therefore, the time to service the powered pivot unit of the present invention is minimized. 
     Furthermore, another aspect of the present invention employs a rotary actuator coupled to the rotating arm assembly through a pair of hub assemblies having drive keys which are mounted on a pair of jack screws. To disengage the drive keys from the rotary actuator, the jack screws are simply rotated in place. Advantageously, the jack screws and drive keys do not become separated from the hub assembly during the disengagement process. This simplified service method assures that these components do not become lost or contaminated by the surrounding environment. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the present invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a powered pivot unit constructed in accordance with the teachings of the present invention; 
     FIG. 2 is an exploded perspective view of the powered pivot unit of the present invention; 
     FIG. 3 is an exploded perspective view of an actuator assembly of the powered pivot unit of the present invention; 
     FIG. 4 is a cross-sectional side view of the actuator assembly constructed in accordance with the teachings of the present invention; 
     FIG. 5 is a cross-sectional view, taken along line  5 — 5  shown in FIG. 4, of the actuator assembly of the present invention; 
     FIG. 6 is an exploded perspective view of a hub assembly of the powered pivot unit constructed in accordance with the teachings of the present invention; 
     FIG. 7 is a cross-sectional side view, taken along line  7 — 7  shown in FIG. 6, of the hub assembly of the present invention; 
     FIG. 8 is a cross-sectional top view, taken along line  8 — 8  shown in FIG. 2, of the powered pivot unit of the present invention; 
     FIG. 9 is an exploded perspective view of an exemplary shock assembly of the powered pivot unit of the present invention; 
     FIG. 10 is a graph depicting lifting capacity per pivot rotation; and 
     FIG. 11 is a graph depicting lifting capacity per distance from the axis of rotation of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1 and 2 show the preferred embodiment of a powered pivot unit  20  constructed in accordance with the teachings of the present invention. Pivot unit  20  includes a frame assembly  22 , an arm assembly or positioning bracket  24 , an actuator assembly  26  and two hub assemblies  28 . Actuator assembly  26  is rigidly coupled to frame assembly  22  via a first pin  30  and a second pin  32 . Arm assembly  24  is drivingly interconnected to actuator assembly  26  via hub assemblies  28 . In FIG. 1, arm assembly  24  is shown in a fully upright first position abutting a first shock assembly  36 . Based on the position of a second shock assembly  38 , arm assembly  24  may rotate about an axis  40  to a second position shown in phantom. The full stroke of actuator assembly  26  is substantially equivalent to 105 degrees of rotation. Frame assembly  22  includes a plurality of keyways  42  for receipt of the shock assemblies. In this manner, a range of arm rotation less than 105 degrees may be defined. Keyways  42  are positioned in 15 degree increments from each other. 
     An additional functional advantage of using powered pivot unit  20  includes versatile mounting. Specifically, frame assembly  22  includes a first mounting surface  44  and a second mounting surface  46  for coupling powered pivot unit  20  to a factory floor, a stantion, a workbench or the like. An exemplary bench  48  is shown as a suitable mounting structure in FIG.  2 . In similar fashion, arm assembly  24  includes a first tool mounting surface  50  and a second tool mounting surface  52  for mounting an exemplary tool  53 . First tool mounting surface is positioned substantially orthogonally to second tool mounting surface  52  to provide increased utility of powered pivot unit  20 . 
     Frame assembly  22  functions to provide a robust support for actuator assembly  26  and arm assembly  24 . Frame assembly  22  includes a first frame plate  54 , a second frame plate  56 , a first mounting plate  58  and a second mounting plate  60 . First mounting plate  58  is substantially identical to second mounting plate  60 . Accordingly, only first mounting plate  58  will be described in greater detail. First mounting plate  58  includes a first recess  64  and a second recess  66  for capturing a portion of first frame plate  54  and second frame plate  56  respectively. A plurality of fasteners  68  secure the frame plates to first mounting plate  58  in a predetermined, offset, and substantially parallel relationship. First mounting plate  58  also includes a plurality of apertures  70  for receipt of fasteners (not shown) for coupling first mounting plate  58  to bench  48 . Second mounting plate  60  also interconnects first frame plate  54  and second frame plate  56 . Second mounting plate  60  is preferably orthogonally positioned relative to first mounting plate  58  to provide a user a choice between first mounting surface  44  or second mounting surface  46 . 
     Because second frame plate  56  is substantially similar to first frame plate  54 , only second frame plate  56  will be described in detail. Second frame plate  56  includes a first pin aperture  72  and a second pin aperture  74  extending therethrough for receipt of first and second pins  30  and  32 , respectively. First pin aperture  72  includes a detent  76  for receipt of a keeper  78  coupled to one end of first pin  30 . A pair of fasteners  80  couple keeper  78  and first pin  30  to second mounting plate  60 . A detent  82  is positioned adjacent second pin aperture to function in the same manner as detent  76 . A keeper  84  is coupled to one end of second pin  32  and positioned within detent  82 . Fasteners  86  couple keeper  84  and second pin  32  to second frame plate  56 . 
     Second frame plate  56  also includes a generally cylindrical counter-bore  88  communicating with a co-axial through bore  90  of a smaller diameter. Counter bore  88  receives and aligns a deep groove ball bearing assembly  91 . A set of three threaded apertures  92  is positioned about each keyway  42  to facilitate mounting of first shock assembly  36  and second shock assembly  38  to second frame plate  56 . First shock assembly  36  may be positioned in any one of four keyways  42  positioned near the top of second frame plate  56 . Second shock assembly  38  may be positioned in one of seven lower keyways  42  for limiting the rotation of arm assembly  24 . The mounting plates and frame plates are preferably constructed from 6061-T651 Aluminum. 
     With reference to FIGS. 3-5, actuator assembly  26  includes a body  94 , a first cover plate  96 , a second cover plate  98 , a vane  100  and a pair of rotary bearings  102 . Body  94  is a generally plate-like structure having an arcuately-shaped bore  104  extending therethrough. A chamber  106  is formed once first cover plate  96  and second cover plate  98  are coupled to body  94  thereby enclosing bore  104 . Body  94  includes an inlet port  108  and an outlet port  110  communicating with chamber  106 . Inlet port  108  and outlet port  110  each include an orifice  112  consisting of a relatively small diameter passageway adjacent chamber  106 . Orifice  112  serves to reduce the volume flow rate of pressurized fluid entering the chamber and minimize possibly high internal impact loads. 
     Body  94 , first cover plate  96  and second cover plate  98  each include a first pin aperture  114  and a second pin aperture  116 . At assembly, actuator assembly  26  is displaced between first frame plate  54  and second frame plate  56 . First pin  30  is inserted through apertures  72  and first pin aperture  114  to couple actuator assembly  26  to frame assembly  22 . Similarly, second pin  32  is inserted through second pin apertures  74  and  116 . Each of the first and second pins extend into first frame plate  54  as well. 
     Vane  100  includes a wiper arm  118  having a generally cylindrical first end  120  and an elongated, substantially rectangular, second end  122 . An opposed pair of co-axially aligned trunions  124  outwardly protrude from wiper arm  118  along axis  40 . Each of trunions  124  includes an outer face  126  having a keyway  128  and a pair of threaded apertures  130  formed therein. Wiper arm  118  includes a pair of grooves  132  continuously extending about the periphery of wiper arm  118 . A pair of seals  134  are disposed within grooves  132 . Each of seals  134  sealingly engage body  94 , first cover plate  96 , second cover plate  98  and vane  100  to prevent pressurized fluid from passing thereby. 
     Rotary bearings  102  are positioned within bearing apertures  136  extending through each of first and second cover plates  96  and  98 , respectively. A pair of elastomeric o-rings  138  are positioned between an inner-race  140  of rotary bearings  102  and trunions  124  of vane  100 . Each rotary bearing  102  is coupled to its respective cover plate by four fasteners  142 . Body  94 , first cover plate  96  and second c over plate  98  are interconnected by a plurality of threaded fasteners  144  and correspondingly internally threaded nuts  146 . 
     Each of hub assemblies  28  are substantially identical to one another. Accordingly, only one hub assembly will be described. With reference to FIGS. 6 and 7, hub assembly  28  includes a hub  148 , a key  150 , a key retraction rod  152 , roll pins  154 , screws  156  and retaining rings  158 . 
     Hub  148  includes an inner cylindrical journal  160 , an adjacent, slightly larger, cylindrical journal  162  and a generally cylindrical flange  164 . Hub  148  also includes a central internally threaded aperture  166  communicating with a substantially rectangular slot  168 . As best shown in FIG. 7, rectangular slot  168  is sized to accept key  150  while aperture  166  is sized to threadingly engage the outer diameter of key retraction rod  152 . 
     Key retraction rod  152  is a substantially cylindrically-shaped member having a first externally threaded end  170  and a stepped second end  172  having a reduced diameter. Second end  172  includes an annular groove  174 . First end  170  includes a hexagonally-shaped receptacle  176 . To construct hub assembly  28 , second end  172  of key retraction rod  152  is inserted within a blind aperture  178  of key  150 . Roll pins  154  are transversely inserted through apertures  180  to axially retain key retraction rod  152 . It should be appreciated that roll pins  154  are positioned to allow key retraction rod  152  to rotate within blind aperture  178 . The external thread of key retraction rod  152  is engaged with internally threaded aperture  1 . 66 . Key retraction rod  152  in combination with key  150  effectively defines a jack screw wherein rotation of key retraction rod  152  axially displaces key  150  within slot  168 . 
     Hub  148  also includes a pair of bores  182  having coaxial counter bores  184 . Each of counter bores  184  include a ring groove for receipt of retaining rings  158 . Counter bores  184  are of sufficient length to allow screws  156  to fully retract within bores  182  before contacting retaining rings  158 . By using this manner of assembly, the sub-components of hub assembly  28  are captured within portions of  148  and will not be lost during service. 
     As shown in FIG. 2, arm assembly  24  includes a pair of rotator arms  186 , a pair of tool mounting plates  188  and a pair of lock-out pin assemblies  190 . Each of rotator arms  186  and tooling mounting plates  188  are substantially flat plates constructed from 6061-T651 Aluminum. Each rotator arm includes a first seat  192  and a second seat  194  having a plurality of threaded apertures  196  formed therein. Each tool mounting plate  188  includes slots (not shown) for receipt of first and second. seats  192  and  194 , respectively. Once the seats are disposed within the slots, threaded fasteners  198  rigidly couple tool mounting plates  188  to rotator arms  186 . Each rotator arm  186  includes an aperture to receive lock-out pin assembly  190 . Lock-out pin assembly  190  includes a housing  200  and a lock-out pin  202 . Lock-out pin  202  is selectively disposable within one of lock-out pin receptacles  62 . Once lock-out pin  202  is disposed within one of the receptacles, arm assembly  24  is fixed relative to frame assembly  22  thereby allowing service to powered pivot unit  20  without reliance upon pressurized fluid within actuator assembly  26 . 
     Reference should now be made to FIGS. 2 and 8 wherein each rotator arm  186  includes an aperture  204  sized to cooperate with journal  162  of hub  148 . Each rotator arm  186  also includes a plurality of threaded apertures  206  for receipt of fasteners  208 . A plurality of pins  210  are slidingly disposed within apertures  212  to accurately align arm assembly  24  to hub assembly  28 . Deep groove ball bearings  91  rotatably connect assembly  24  with frame assembly  22 . Each ball bearing  91  is disposed within a counter bore  88 . A washer  214  is positioned between each bearing  91  and rotator arm  186 . FIG. 8 depicts key  150  in the engaged position disposed within keyway  128  of vane  100 . As such, actuator  26  is drivingly coupled to positioning bracket  24 . An additional driving interconnection exists between screws  156  and vane  100 . 
     Actuator assembly  26  may also be drivingly disconnected from hub assembly  28 . It should be appreciated that slot  168  is of sufficient depth to allow key  150  to be fully retracted within slot  168 . A stop face  216  of key  150  contacts a bottom face  218  of slot  168  when key  150  is fully retracted. Therefore, key  150  is in a disengaged position clear of keyway  128  once stop face  216  engages bottom face  218 . Screws  156  may be rotated out of threaded engagement with vane  100  to completely disengage actuator assembly  26  from positioning bracket  24 . 
     With reference to FIG. 9, first shock assembly  36  will be described in detail. It should be appreciated that first shock assembly  36  is substantially identical to second shock assembly  38 . Accordingly, only first shock assembly  36  will be described in detail. First shock assembly  36  includes a shock mount  220 , a shock absorber  222 , a crowned stop block  224 , and a proximity switch  226 . A set of three threaded fasteners  228  cooperate with shock mount  220  and threaded apertures  92  of second frame plate  56  to couple first shock assembly  36  to frame assembly  22 . Shock absorber  222  includes a shock housing  230  having a piston  232  slidingly positioned therein. Shock housing  230  has a externally threaded portion engaged with an internally threaded aperture  234 . Crowned stop block  224  is preferably constructed from a hardened ASC020 material. Both proximity switch  226  and crowned stop block  224  are coupled to shock mount  220  using standard fastening techniques. 
     Referring to FIG. 2, a pair of flat stop blocks  236  are shown coupled to an edge of rotator arm  186 . Each of flat stop blocks  236  are positioned to engage crowned stop blocks  224  at the desired rotational stroke limit. One such stroke limit position is depicted in FIG. 1 where crowned stop block  224  of the first shock assembly  36  engages flat stop block  236  mounted at the upper end of rotator arm  186 . A pair of contact bolts  238  are also mounted to the edge of rotator arm  186 . Each of contact bolts  238  are positioned to engage piston  232  at a point in time before flat stop block  236  engages crowned stop block  224 . Therefore, shock or impact type loading between the hardened stop blocks is avoided by assuring that shock absorber  222  dissipates most of the energy of rotation. A pair of sensor pins  240  are positioned adjacent flat stop block  236  and mounted to rotator arm  186 . Sensor pins  240  are positioned to rotate within sensing proximity of proximity switch  226  once flat stop block  236  engages crowned stop block  224 . 
     During operation, first shock assembly  36  may be positioned in any one of the four upper most keyways  42  to limit the rotation of arm assembly  24  in a clockwise direction. Similarly, second shock assembly  38  may be positioned in any one of the seven lower keyway positions to limit the rotation of arm assembly  24  in a counter-clockwise direction. No additional effort is required to separately relocate proximity switches or shock absorbers when an angular rotation change is desired. It should also be appreciated that first frame plate  54  also includes a plurality of like keyways (not shown) to assist the user in the manufacturing environment by allowing the stops and proximity switches to be mounted on the opposite side of frame assembly  22 . In similar fashion, flat stop block  236 , contact bolt  238  and sensor pin  240  may be mounted to either or both rotator arms  186 . 
     Powered pivot unit assembly and actuator assembly removal will now be described. Frame assembly  22  and arm assembly  24  may be separately constructed. Specifically, first frame plate  54  and second frame plate  56  are coupled to first mounting plate  58  and second mounting plate  60  to form frame assembly  22 . Similarly, two rotator arms  186  are coupled to two tool mounting plates  188  to form arm assembly or positioning bracket  24 . 
     To continue in modular unit assembly fashion, actuator assembly  26  may be separately constructed by placing vane  100  within body  94  and coupling the first and second cover plates  96  and  98 , respectively to body  94 . Rotary bearings  102  are positioned over trunions  124  and coupled to the respective cover plate. At this time, either actuator assembly  26  or arm assembly  24  may be coupled to frame assembly  22 . For example, to interconnect actuator assembly  26  to frame assembly  22 , actuator assembly  26  is positioned between first frame plate  54  and second frame plate  56  to align first pin aperture  114  With first pin aperture  72 . Second pin aperture  116  of actuator assembly  26  is aligned with second pin aperture  74  of the first and second frame plates. First pin  30  and second pin  32  are disposed within the respective pin apertures to couple actuator assembly  26  to frame assembly  22 . Keeper  78  is coupled to second mounting plate  60  to maintain the correct axial position of first pin  30 . Similarly, keeper  84  is coupled to second frame plate  56  to maintain the axial position of second pin.  32 . Ball bearings  91  are disposed within counter bores  88 . Arm assembly  24  is placed into position to align aperture  204  along axis of rotation  40 . Washer  214  is positioned between each of rotator arms  186  and their respective frame plate while hub assemblies  28  are axially inserted along axis  40 . Inner cylindrical journal  160  engages an inner race  242  of bearing  91  as journal  162  engages aperture  204  of rotator arm  186 . 
     It should be appreciated that if key  150  is in the extended position as shown in the figures, hub assembly  28  must be rotated until key  150  aligns with and engages keyway  128  of vane  100  before hub assembly  128  may be fully seated. Hub assembly  28  is fully seated when flange  164  abuts rotator arm  186 . Screws  156  axially retain hub assembly  28  to vane  100 . Pins  210  and threaded fasteners  208  couple hub assembly  28  to arm assembly  24 . The peripheral hardware such as first shock assembly  36 , second shock assembly  38 , lock-out pin assemblies  190 , flat stop block  236 , contact bolt  238  and sensor pins  240  may be assembled at their respective locations at any time. It is noteworthy that once hub assembly  28  interconnects the aforementioned components, pressurized fluid entering inlet port  108  or outlet port  110  will cause arm assembly  24  to rotate about axis  40 . 
     One powered pivot unit  20  has been assembled and placed into use, actuator assembly  26  may be replaced by following the procedural steps described hereinafter. Exemplary tool  53  need not be removed from arm assembly  24 . Additionally, frame assembly  22  need not be disconnected from exemplary bench  48 . To temporarily fix arm assembly  24  to frame assembly  22 , lock-out pin  202  is engaged within the nearest receptacle  62 . An external tool such as an allen wrench (not shown) is disposed within threaded aperture  166  to engage receptacle  176  of key retraction rod  152 . Counter-clockwise rotation of key retraction rod  152  causes key  152  to axially move toward flange  164 . Preferably, key retraction rod  152  is rotated until stop face  216  of key  150  abuts bottom face  218  of slot  168 . This procedure is to be repeated for both hub assemblies  28 . Screws  156  are rotated to threadingly disengage them from vane  100 . Keepers  78  and  84  are next disconnected from second frame plate  56 . Finally, first and second pins  30  and  32  are removed from their apertures. Actuator assembly  26  may now be removed. The aforementioned procedural steps may be performed in reverse order when installing a repaired or replacement actuator assembly. 
     In operation, powered pivot unit  20  accepts a pressurized fluid, preferably air, at both inlet port  108  and outlet port  110 . A pressure differential is generated by a suitable power source such as an air compressor (not shown) across inlet port  108  and outlet port  110 . Accordingly, vane  100  responds by rotating toward the low pressure port. It is anticipated that a generally flat, constant torque output (negating the effect of inertial and gravitational forces) will be generated by the powered pivot unit of the present invention. With reference to FIG. 10, the force generated at a given distance from axis of rotation  40  will be substantially constant for each rotational position of vane  100 . As such, the lifting capacity will be linearly related to the distance from axis  40  as depicted in FIG.  11 . Vane  100  will continue to rotate until arm assembly  24  contacts the first shock assembly or the second shock assembly depending on the direction of rotation. The rotational direction of vane  100  may be reversed by simply pressurizing the opposite port. 
     While a preferred embodiment of the present invention has been disclosed herein, other aspects fall within the scope of the present invention. For example, other actuator to positioning bracket coupling mechanisms may be employed which use additional links or fasteners to drivingly interconnect the vane to the positioning bracket. Moreover, the removable actuator features may apply to clamps, grippers and part locators. The external disengagement tool may alternately be a screwdriver and may even be attached to the powered pivot unit. Other switch positioning angles and the total rotational angular range may be varied. While various materials have been disclosed, other materials may be employed. 
     The foregoing discussion discloses and describes merely exemplary embodiments of the present invention. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings a n d claims, that various changes, modifications and variations may be made therein without department from the spirit and scope of the invention as defined in the following claims.