US3790814A - Electrical lowering apparatus - Google Patents

Electrical lowering apparatus Download PDF

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Publication number
US3790814A
US3790814A US3790814DA US3790814A US 3790814 A US3790814 A US 3790814A US 3790814D A US3790814D A US 3790814DA US 3790814 A US3790814 A US 3790814A
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United States
Prior art keywords
electrical
moving
switch
brake
braking
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Expired - Lifetime
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English (en)
Inventor
H Pfaff
W Bowser
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PFAFF AND KENDALL
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PFAFF AND KENDALL
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C13/00—Other constructional features or details
    • B66C13/18—Control systems or devices
    • B66C13/22—Control systems or devices for electric drives
    • B66C13/23—Circuits for controlling the lowering of the load

Definitions

  • ABSTRACT 1 An electrical lowering apparatus, for lowering and elevating a mounted fixture, which is provided with braking means which secure the brake by coupling the brake directly to the moving means to prevent brake bypass in the event of mechanical or electrical failure and which engage the brake for the initial distance of lowering and for the final distance of elevating by correlating the tripping of the brake limit switch to movement of the moving means to cushion the separation and connection operations, which is further provided with electrical operating means which control the driving means by independently generating the control signal for the power circuit to prevent extraneous electrical interference and which control the braking means by separately operating the brake solenoid and the motor in the power circuit to prevent motorgenerated current interference, and which is further provided with overriding means which bypass the driving means by enabling coupling of a shaped portion of the
  • PATENTEU FEB 74 SHEET 3 OF 5 PATENTEU 51974 sumunfs PATENTEDFEB 51914 3,790,814
  • the moving means could not be operated if the driving means were disabled by a mechanical or electrical failure.
  • FIG. 1 is a front, partly broken, elevational view of an electrical lowering apparatus, pursuant to the invention
  • FIG. 2 is a side, partly broken, elevational view thereof, taken at line 2-2 of FIG. 1;
  • FIG. 3 is a side, partly broken elevational view thereof, taken at line 3-3 of FIG. 1;
  • FIG. 4 is a schematic view of the motor power circuit
  • FIG. 5 is a schematic view of the signal circuit.
  • the electrical lowering apparatus 11 (FIGS. 1-3) for example, comprises a housing 12, driving means 13, moving means 14, braking means 15, electrical operating means 16 (FIGS. 3-5), and overriding means 17. v
  • the housing 12 (FIG.' 1) for example, comprises an upper portion 20, which may be secured to any desired or convenient anchoring means such as a ceiling, beam, or other support, or suspended by a pipe or other means from such support, a housing frame 21, a housing cover 22 which may be secured about the housing frame 21 and which, in the preferred embodiment, is secured at the upper portion thereof to prevent tampering with the apparatus and a lowering plate 23, to
  • fixture or other object to be elevated may be mounted or secured by any desired or convenient means.
  • Driving means 13 for example, FIGS. 2 and 3, comprises a motor 30 which is mounted to the housing frame 21, and which, in the preferred embodiment, is a permanent magnet brush-type DC motor, and which is connected to line current through a power transformer 31,and a motor drive shaft 32 which extends through the motor 30.
  • a motor 30 which is mounted to the housing frame 21, and which, in the preferred embodiment, is a permanent magnet brush-type DC motor, and which is connected to line current through a power transformer 31,and a motor drive shaft 32 which extends through the motor 30.
  • Moving means 14 for example (FIGS. 1 and 2), comprises a driver sprocket 40 which is keyed to the motor drive shaft 32, a worm shaft 41 which is rotatably journalled in the housing frame 21, a driven sprocket 42 which is keyed to the worm shaft 41, and a chain 43 which is entrained about the driver sprocket 40 and the driven sprocket 42 and which couples the worm shaft 41 to the motor drive shaft 32, a worm 44 which is mounted on the worm shaft-41, a worm gear shaft 45 which is rotatably journalled in the housing frame 21, a worm gear 46 which meshes with the worm 44 and which is positioned on worm gear shaft 45 in common with tape storage drums 47,47 which are positioned on both ends'of the worm gear shaft 45, and a pair of tapes 48,48, which are wound at one end thereof on the tape storage drums 47, 47', pass over the idler guide rollers 49, 49 (FIG.
  • tape connector clamps 50,50 which include upper tapered portions 51,51.
  • Each of the tape connector clamps 50,50 is connected at the other end thereof to the lowering plate 23 by connectors 52,52, and the mounted fixture (not shown) is secured to the apparatus by a connector (not shown) which is coupled through aperture 53 in the lowering plate 23.
  • the braking means 15 comprises, for example, a solenoid 60 which is mounted to the housing frame 21, a magnetic plunger 61 which extends through the solenoid 60 and which is movable thereby, a linkage rod 62 which is connected to the magnetic plunger 61 and which moves therewith, a bearing plate 63 which extends about the linkage rod 62 at a point along the length thereof, a brake spring 64 which operates in conjunction with linkage rod 62 through connectors 65,65 and which bears against the bearing plate 63 at one end thereof for biasing of the linkage rod 62 thereby, a brake retractor 66 which extends about and is mounted to the linkage rod 62 at one end thereof and which extends around the worm shaft 41 and pivots to act against a brake shoe 67 including a face portion which preferably comprises cork or other similar material which provides a relatively high coefficient of friction, wet or dry, which is located on the worm shaft 41 between the brake shoe 67 and the driven sprocket 42.
  • the solenoid 60 is electrically connected to a brake limit switch 68, which is interposed in the path of movement of tape 48 and tape connector clamp 50 including upper tapered portion 51 thereof, switch 68, comprising a casing 69, a switch (not shown) which in the preferred embodiment is a normally closed switch positioned inside the casing 69, a lever arm 70 one end of which is connected to the switch in the casing 69, and a roller 71 which is connected to the other end of lever arm 70.
  • the mounted fixture (not shown) is connected by wiring through the connector (not shown) in the aperture 53 to a barrier terminal block (not shown) to a'plurality of fixture contact switches 73,73, (FIG.
  • the fixture limit switches 72, 72 are interposed in the path of movement of tape 48 and tape connector clamp 50 including upper tapered portion 51 thereof, and comprise casings 74, 74', switches (not shown) which in the preferred embodiment are normally open switches posi-' tioned inside the casings 74, 74, lever arms 75, 75', one end of each of which is connected to the switches in the casings 74,74, and rollers 76,76 each of which is connected to the other end oflever arms 75, 75'.
  • the fixture contact switches 73, 74', 73", 73” each include a movable contact button 77 which is mounted in the lowering plate 23, and which is mounted in the housing frame 12.
  • the electrical operating means 16 (FIGS. 4 and for example, comprises a power circuit 80, and a signal circuit 81.
  • the power circuit 80 is physically located in the housing 12 and comprises, for example, (FIG. 4), a rectifier circuit 82 which is connected to the power transformer 31 and to the motor 30, and a firing circuit 83.
  • the rectifier circuit 82 comprises a pair of siliconcontrolled rectifiers 84, 84, and a pair of triacs 85,85, in series with a pair of diodes-86,86 which cause the triacs to perform as a pair of silicon-controlled rectifiers to permit one common reference point for the firing of all four of the rectifier circuit control elements.
  • the firing circuit 83 comprises steering diodes 87, 87', 87 87", dropping resistors 88,88',88", and a filter network 89 which includes resistor 90 and capacitor 91.
  • the power circuit 80 is connected to a line current supply (not shown) at a control panel at floor level (not shown) through two wires (not shown) which are connected from terminals in the control panel to corresponding terminals in the power circuit in the housing 12.
  • the signal circuit 81 is physically located in the control panel at floor level (not shown), and comprises, for example, a signal transformer 92, an on-off switch 93 connected to the signal transformer 92, a rectifier circuit 94, and an updown switch 95 which is connected to the rectifier circuit 94 and to terminals B,B.
  • the rectifier circuit-94 comprises a full wave bridge rectifier which includes a first pair of opposing diodes 96,96, and a second pair of opposing diodes 97,97, each of which conducts on alternate half cycles, a ca-' pacitor 98 which filters the AC full wave source to give the required DC level, and a resistor 99 which bleeds the capacitor 98 when the apparatus is turned off.
  • the signal circuit 81 is connected to the line current supply (not shown) in the control panel at floor level (not shown), and is connected to the terminals A,A' in the housing 12, to which the solenoid 60 and the brake limit switch 68 are connected in series, through two wires (not shown) which are connected to the terminals B,B in the control panel.
  • the overriding means 17 (FIG. 2), for example, comprises a shaped portion 100 of the moving means 14, which, in the preferred embodiment comprises a pinned hex-nut shaped portion on the upper end of the worm shaft 41, and an access cap 101 which is seated on the housing portion 20 and which covers the shaped portion 100.
  • the operator actuates the on-off switch 93 to on, whereupon idling line current is conducted from the supply (not shown) through the signal transformer circuit 82 in the power circuit 80.
  • the operator then actuates the up-down switch 95 to down, whereupon operating current is conducted from the rectifier circuit'94 in the signal circuit 81 through the down connections of the updown switch 93 to the terminals B',B, through the connecting wires (not shown) to the terminals A,A in the housing 12, where the signal comprises a negative DC signal at point A with respect to point A which triggers the firing circuit 83 to fire the triacs 85,85 and the diodes 86,86 by the negative DC voltage applied to their gate terminals, whereupon operating current is conducted from the rectifier circuit 82 through the motor 30 -in a direction which produces clockwise rotation of the motor drive shaft 32, which in turn produces corresponding rotation of the driver sprocket 40, the chain 43, the driven sprocket 42, the
  • the travel which the'solenoid 60 imparts to the magnetic plunger 61 is transmitted through the linkage rod 62 and the connector 65 to compress the brake spring 64 and release the loading thereof, to release the brake shoe 67 from its biased position against the face of the driven sprocket 42, to thereby release the braking means from engagement with the moving means 14.
  • the initial lowering movement against the action of the brake absorbs the effects of the separating forces and reduces the hazard of rapid separation damage to the mounted fixture and to the electrical lowering apparatus.
  • the operator activates the on-off switch 93 to on," whereupon idling line current is conducted from the supply (not shown) through the'signal transformer 92 and the rectifier circuit 94 in the signal circuit 81,
  • the signal comprises a positive DC signal at point A with respect to point A which triggers the firing circuit 83 to fire the I silicon-controlled rectifiers 84,84 by the positive DC voltage applied to their gate terminals, whereupon operating current is conducted from the rectifier circuit 82 through the motor 30 in a direction which produces counterclockwise rotation of the motor drive shaft 32, which in turn produces corresponding rotation of the driver sprocket 40, the chain 43, the driven sprocket 42, the worm shaft 41, the worm 44, the worm gear 46, and the worm gear shaft 45, which in turn causes clockwise rotation of the tape storage drums 47,47 to re wind the tapes 48,48, and elevate the tape connector clamps 50,50, the lowering plate 23, and the mounted fixture, until the tapes 48,48 rewind to the point where the roller 71 on the lever arm moves along the outer surface of upper
  • the travel which the loading of the brake spring 64 imparts to the magnetic plunger 61 is transmitted through the linkage rod 62 and the brake retractor 66, to push the brake shoe 67 into a biased position against the face of the driven sprocket 42, to thereby engage the braking means 15 with the moving means 14.
  • the final movement against the action of the brake shoe 67 absorbs the torque of the rotor 'in the motor 30 and reduces the hazard of impact shock damage to the mounted fixture and t0 the electrical lowering apparatus.
  • the fixture contact switches 73,73, 73", 73" are connected prior to the tripping of the fixture limit switches 72,72 which occurs after further rewinding of the tapes 48,48 when the rollers 76,76 on'the lever arms 75,75 move along the outer surface of the upper tapered portion 51 and the tape connector clamp 50, whereupon the lever arms 75,75 are biased to positions distant from the switches in the casings 74, 74 which trips the switches, the fixture limit switches 72,72 are tripped closed.”
  • the completing of circuit continuity through the fixture contact switches 73,73, 73", 73 prior to the tripping of the fixture limit switches 72,72 eliminates the hazard of arcing during the elevating operation.
  • the access cap 101 is removed from the upper portionv 20 of the housing 12, and suitable means such as a right angle drive are connected to the shaped portion and are operated to drive the worm shaft 41, the worm 44, the
  • the roller 71 which is operatively connected to the lever arm 70 and biased thereby, follows the contours of the outer surface of the tape connector clamp 50 including upper tapered portion 51 thereof, upon lowering or elevating of the mounted fixture, and generates corresponding biasing of the pilot pin 70 to a position adjacent to the switch in the casing 69 for the initial distance of lowering and for the final distance of elevating, whereby the brake limit switch 68 is tripped open during movement of the roller 71 for such distances, whereupon the solenoid 60 is open-circuited and deenergized to release the magnetic plunger 61 and the linkage rod 62 connected thereto, and the brake shoe 67 is biased against the driver sprocket 41 by the loading in the brake spring 64, transmitted through the connector 65, the linkage rod 62 and the brake retractor 66, so that such movement progresses against the operation of the braking means 15, to thereby absorb the stress and strain forces generated on lowering the oper ating elements and to cushion the motor rotor torque forces generated on elevating the operating elements
  • the brake shoe 67 is positioned on the worm shaft 41 in common with the driven sprocket 42 on which the brake shoe67 acts to couple the braking means directly to the moving means 14, so that if the chain 43, which connects the driver sprocket 40 to the driven sprocket 42, breaks or disengages, or if the motor 30 shuts down, or if there is an electrical failure in the apparatus, the mounted fixture will not drop, because it is secured in position by the continued engagement of the braking means 15 with the moving means 14.
  • the signal circuit 81 generates an independant control signal by converting line current from the supply to operating current for firing the rectifier circuit 82 through the signal transformer 92, the rectifier circuit 94, the directional wiring of the up-down switch 95 and the connecting wires to the terminals A,A' and to the firing circuit 83 in the housing 12, which controls the firing of the rectifier circuit 82 to direct the movement of current through the motor 30 to provide controlled rotation of the motor drive shaft 32 thereby, to thereby prevent extraneous RF signals in the vicinity of the apparatus, generated by motors or other electrical devices, from interfering with the operation of the apparatus by causing uncontrolled firing of the control elements in the rectifier circuit 82 to conduct current through the motor and rotate the motor drive shaft thereby.
  • the signal circuit 81 controls the solenoid 60 and the motor 30 separately, by connection of the solenoid 60 in series with the brake limit switch 68 to terminals A,A in the housing 12, to thereby prevent counter EMF current, generated by the motor 30 during the lowering operation by gravitational force acting on the moving means 14 and the driving means 15 to cause the motor drive shaft 32 to rotate after the power is turned off, from interfering with the opencircuiting of the solenoid 60 which is necessary for brake actuation, by conducting motor-generated current therethrough.
  • the two wires which connect the signal circuit 81 to the power circuit 80, the two wires which connect the signal circuit 81 to the terminals A,A in the housing 12, are the only wire connections required from the control panel at floor level to the elevated housing 12 to control each electrical lowering apparatus 11.
  • the low voltage signal circuit 81 enables the use of wires which are not enclosed in conduit for connections from the control panel to the housing, thereby greatly increasing the utility of the apparatus and the efficiency and safety of installation thereof.
  • the shaped portion is accessibly positioned on the upper end of the worm shaft 41 beneath the removable access cap 101 to enable an'external drive to be coupled through engagement therewith to drive the moving means 14 to elevate or lower the mounted fixture, to thereby enable moving means 14 operation if there is a mechanical or electrical failure in the driving means 13.
  • Apparatus for lowering and elevating a fixture comprising:
  • iii. means, at said position, for braking said moving means
  • v. means traversing said positions and interconnecting the driving and moving means, and, for safety, braking said moving means even when disconnected from the driving means.
  • switch operating means on the moving means electrical switch means mounted in the housing in'the path of movement of the moving means,-for engagement therewith, and connected to the braking means, said braking means including electrical means for retarding the braking means during such times as the switch operating means engages the switch means, whereby said brake means will continue to be operative, for safety, in relation to the moving means, notwithstanding any interruption of connection of the driving and moving means.
  • second switch operating means on the moving means second electrical switch means mounted in the housing in the path of movement of the moving means, and of the second switch operating means, electrical fixture .contact switches on the lowering plate, and connected to the second electrical switch means, whereby said electrical fixture contact switches will be disconnected from said second electrical switch means when said second switch operating means so engages said second electrical switch means.
  • electrical fixture means on said plate comprising fixed contact buttons therein and movable contact buttons positioned in said plate movably in relation to the fixed contact buttons and adapted to engage said fixed contact buttons to close the circuit to any fixtures on the plate connected to said fixed contact buttons on movement of the plate into closing contact with the housing.
  • said braking means including means engageable with the driving means, and electrical means for retarding the braking means, on actuation of said electrical means, electrical switch engaging means on the moving means and movable therewith, and electrical switch means in the housing in the path of movement of the moving means and electrically connected to said electrical means, to actuate the electrical means, for retarding the braking means from engagement with the driving means when said electrical switch means is so engaged on said movement of the moving means.
  • said means for so retarding the braking means comprising solenoid means.
  • means electrically operating the braking means and the driving means comprising a current supply, means for electrically powering the driving means, which are connected to the current supply, and means for electrically controlling the braking means and the driving means, which are connected to.
  • the electrical controlling means comprising first means for switching the current supply, a first voltage transformer, which is connected to the first switching means and which isoperable upon'closing of the first switching means, first means for rectifying the current, which are connected to the first voltage transformer and which are operable upon closing of the first switching means to rectify the current to comprise an operating current, second means for switching the operating current, which are connected to the first rectifying means, and means for connecting the second switching means to the braking means and to the electrical powering means, to enable the operating current to be conducted therethrough upon closing of the second switching means in one direction or in the other direction, the power supplying means comprising a second voltage transformer, which is connected to the first switching means and which is operable upon closing of the first switching means, second means for rectifying the current, which are connected to the second voltage transformer and which are operable upon closing of the first switching means to rectify the current to comprise an operating current, and means for firing the second rectifying means and the electrical controlling means, and which are operable upon the closing of the second switching means and the
  • the braking means comprising a brake member positioned on and engageable with the moving means, and means for controlling the brake member, operable in conjunction with the moving means, such that, upon actuation thereof by the moving means, the brake member is engaged with the moving means
  • said brake controlling means comprising a switch, mounted to the housing in the path of the moving means, and operable in conjunction with the moving means, means for actuating the brake member, connected to the switch
  • the brake actuating means comprising a solenoid, mounted to the housing and connected to the switch and to the electrical controlling means, said solenoid including an extending plunger, linkage means connected to the plunger, a brake spring, connected to and operating to bias the linkage means, and a brake retractor, connected to the linkage means, and mounted adjacent the braking means.
  • the moving means comprises a worm shaft rotatably journalled in the housing, first means for connecting the worm shaft to the moving member, and second means for connecting the worm shaft to the driving means
  • the first connecting means comprising a first gear mounted on the worm shaft, a gear shaft rotatably journalled in the housing, a second gear mounted on the gear shaft and meshing with the first gear, and means for coupling the second gear to the moving member
  • the second connecting means comprising a driven member mounted to the worm shaft and positioned adjacent the brake member for engagement therewith, and a coupling member, connected to the driven member and the driving means to couple the movements thereof.
  • overriding driving means comprising a shaped portion on the upper end of the worm shaft, whereby an external drive may be coupled through engagement therewith to drive the moving means to elevate or lower the mounted fixture, to thereby enable moving means operation if there is a mechanical or electrical failure in the driving means.
  • An electrical lowering apparatus as set forth in claim 8, in which the switch is connected to the actuating means and the electrical controlling means, a lever arm connected to the switch at one end thereof and a roller connected to the other end of the lever arm and biased by the lever arm into the path of the moving means, for contact therewith, to actuate theswitch.
  • the coupling means comprising a pair of tape drums mounted to the worm gear shaft, a pair of tapes, each wound, at one end thereof, on a tape storage drum, and a pair of tape connector clamps, connected to the other ends of the tapes.
  • means for electrically operating the fixture comprising a current supply, means for connecting the current supply to the fixture, and first means for switching the current to the fixture connecting means, operable in conjunction with the moving means, such that upon actuation thereof by the moving means, the current is conducted to operate the fixture, the first switching means comprising a normally open switch connected to the connecting means, a lever arm connected to the switch at one end thereof, and a roller connected to the other end of the lever arm and biased by the lever arm into the path of the moving means for contact therewith to actuate the switch.

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  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Mechanical Engineering (AREA)
  • Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
  • Control And Safety Of Cranes (AREA)
US3790814D 1972-06-06 1972-06-06 Electrical lowering apparatus Expired - Lifetime US3790814A (en)

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US26030372A 1972-06-06 1972-06-06

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US3790814D Expired - Lifetime US3790814A (en) 1972-06-06 1972-06-06 Electrical lowering apparatus

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JP (1) JPS4931044A (cs)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5568970A (en) * 1994-07-18 1996-10-29 Prineppi; Frank J. Apparatus for moving an ornament and drive means therefor
US20050253125A1 (en) * 2004-04-27 2005-11-17 National-Oilwell, L.P. Electric winch

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3610584A (en) * 1969-01-21 1971-10-05 Pfaff & Kendall Lowering device mechanism

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3610584A (en) * 1969-01-21 1971-10-05 Pfaff & Kendall Lowering device mechanism

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5568970A (en) * 1994-07-18 1996-10-29 Prineppi; Frank J. Apparatus for moving an ornament and drive means therefor
US20050253125A1 (en) * 2004-04-27 2005-11-17 National-Oilwell, L.P. Electric winch
US7185881B2 (en) * 2004-04-27 2007-03-06 National-Oilwell, L.P. Electric winch

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JPS4931044A (cs) 1974-03-20

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