Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B66—HOISTING; LIFTING; HAULING
  • B66B—ELEVATORS; ESCALATORS OR MOVING WALKWAYS
  • B66B9/00—Kinds or types of lifts in, or associated with, buildings or other structures
  • B66B9/02—Kinds or types of lifts in, or associated with, buildings or other structures actuated mechanically otherwise than by rope or cable
  • B66B9/025—Kinds or types of lifts in, or associated with, buildings or other structures actuated mechanically otherwise than by rope or cable by screw-nut drives
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16H—GEARING
  • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
  • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
  • F16H25/20—Screw mechanisms
  • F16H25/24—Elements essential to such mechanisms, e.g. screws, nuts
  • F16H25/2454—Brakes; Rotational locks

Definitions

• Elevator machinery including friction brake.
• the present invention relates to machinery for a screw drive elevator, comprising a preferably trapezoidal threaded screw and, mounted thereon, a nut provided with a corresponding thread as well as a drive device, said nut bearing a payload and said drive device having a first gear and at least one drive means connecting the first gear to a second gear, which is mounted on the shaft of a drive motor, by means of which the nut or the screw is rotatable depending on the regulation of the motor and depending on a friction brake.
• the screw is, as a rule, made of steel, while the nut is usually made of bronze.
• Under the nut there is a so-called fall-stop nut as extra insurance, so that the load cannot fall down when the nut has become too worn.
• the fall-stop nut has driver ele ⁇ ments engaging cooperating means on the elevator nut, so that the fall-stop nut follows the movement of the elevator nut.
• the eleva ⁇ tor nut is rotatably mounted via a ball bearing in a housing, which is a mounting for a drive motor and supports the eleva ⁇ tor car and the payload.
• the housing with the drive motor and the elevator car are prevented from rotating by means of rails mounted in the elevator shaft, said rails guiding the car by means of guides fixed to the housing or elevator car.
• the elevator if there is a power failure, must not be a b le to f all, out of control, to the bottom of the elevator shaft, and therefore the screw and nut in a conventional screw drive elevator have a relatively small lead angle, as a rule no greater than about 6°, so that the screw and nut will b e self-braking relative to each other when axially loaded. At greater lead angles, this effect ceases. With such a small lead angle, the efficiency of the device is correspondingly low, at most about 30%, requiring unnecessarily large amounts of energy, high rpm of the elevator nut and slow movement of the elevator machinery in both directions.
• the elevator will stop in its current position and can only be returned to an entering or exit position by supplying energy manually or by means of an auxiliary unit, via a special emergency operating device.
• the elevator machinery according to the invention has, how ⁇ ever, a relatively large lead angle, 20-40 , and thus lacks the self-braking effect between the screw and the nut.
• This lead angle achieves, with an optimization of mate ⁇ rial selection and cooperation between the components of the machinery, at least a doubling of the efficiency. Since the elevator machinery no longer spontaneously stops at the posi ⁇ tion in question when the power supply to the nut is stopped, a special braking device is required which ensures that the elevator machinery will be reliably locked to the screw any time the elevator stops for entry or exit. Furthermore, the ⁇ machinery must be locked automatically at the current posi ⁇ tion when there is a power failure, for example.
• the braking device With the aid of the braking device, it is possible to reliably lower the elevator car, without supplying extra power, to the next floor, so-called emergency lowering.
• This emergency lowering should be able to be controlled from the elevator car.
• the purpose of the invention is therefore to provide an ele ⁇ vator machinery of the type described by way of introduction, which makes it possible, while maintaining or improving the margin of safety, to achieve at least a doubling of the effi- ciency, at the same time as the life of the elevator nut is substantially increased.
• the friction brake comprises first and second brake means, at least one frictional surface and has a disengaging device, that at least one of the brake means is non-rotatably connected to either the screw or the nut, and that the con ⁇ tact pressure necessary for the braking effect on the braking means is generated by the load acting on the elevator machi ⁇ nery.
• the braking means are displaceable relative to each other against the effect of the load by means of the dis ⁇ engaging device, between two limit positions along the cen- terline of the screw, said limit positions defining a rest position and a work position for the machinery.
• a preferred embodiment of the invention is characterized in that the nut is rotatably suspended in a housing connected to the drive device, said drive device having a first gear surrounding and non-rotatably fixed to the nut, that the first gear is a nut gear and the second gear is a drive gear, and that the first brake means is formed of the nut housing and the second brake means is formed of the nut gear.
• the load in the rest position is borne by the screw via the housing, a friction fitting, the nut gear and the nut.
• the disengaging device is activated whereby the nut gear is unloaded and a thrust bearing is loaded instead. The load is thereby borne by the screw via the housing, the disengaging device, a bearing sleeve, the thrust bearing and the nut.
• One advantageous further development and improvement of the invention is characterized in that the friction brake com- prises an annular lateral surface of the nut gear facing the housing, and an opposing annular end surface of the housing. Between these surfaces there is a wear layer and both the surfaces and the wear layer surround the screw concentrical ⁇ ly.
• the disengag ⁇ ing device is preferably hydraulically operated and comprises two telescoping annular elements disposed about the center axis of the screw: an annular cylinder and an annular piston enclosing between them an annular chamber which communicates with a hydraulic pump which is operated in response to con ⁇ trol signals from a control unit.
• the coaxial alignment of the nut and the monitoring of the load and operating states is provided according to this embodiment by virtue of the fact that the nut is separated from the bearing and the second brake means, which is made in one piece with the nut gear which rests, via an angle compen ⁇ sator, on the nut, that the nut gear is non-rotatably joined to the nut and that the angle compensator is thereby capable of taking up angular deviations between the nut and the nut gear, whereby the nut can run in coaxial alignment on the screw.
• the nut has at least one driver pin for torque transmitting engagement about the center axis and via the drive housing, with the nut gear which is disposed diametrically surrounding the bearing.
• the angle compensator is made of an annular cylinder and an annular piston enclosing between them a fluid which evenly distributes the contact pressure between the cylinder and the piston even when there is angular misalignment therebetween.
• the nut housing has a cylinder, and the housing and the first brake means are made as two components axially displaceable relative to each other and which are non-rotatably joined to each other.
• the brake means comprises a load sensor coupled between the brake means and the housing, the load sensor having at least one sensor element with an essentially linear characteristic curve and/or at least one sensor of on/off type.
• the load sensor has an annular chamber and an annular piston, and a fluid enclosed between the chamber and the piston which is in communication with at least one sensor element.
• Each load sensor element and pulse sensor element, as well as each additional sensor element sends signals to the control unit depending on what signals can be registered for the current load and the current operating state of the elevator machinery by the control unit, thus making possible monitor- ing and positioning of the elevator machinery by correspond ⁇ ing operation of the nut, in response to the signals received from the sensor elements.
• An additional embodiment of the invention is possible, by making the friction brake electronically instead of hydrau- lically disengageable.
• the disengaging device and the thrust bearing are combined in a bearing clutch comprising two annular magnet elements, an electromagnet and a permanent magnet.
• the bearing clutch acts as an electromagnetic clutch, whereby the need for a special thrust bearing is eliminated.
• Figure 1 shows a partially sectioned side view of a preferred embodiment of the elevator machinery with hydraulic disengaging device
• Figure 2 shows a detailed view of a possible belt monitoring means
• Figure 3 shows a block circuit diagram of the control system for the elevator machinery
• Figure 4 shows a similar view to Figure 1 of a variant of the elevator machinery with an electronic disengaging device and an electromechanical thrust bearing
• Figure 5 shows a similar view to Figure 1 of a particularly simple, mechanically operated variation
• Figure 6 shows, in section, a rotational speed regulator in ⁇ cluded in the machinery according to Figure 5
• Figure 7 is a schematic diagram showing the function of the mechanical operating system according to Figures 5 and 6
• Figure 8 shows a partially sectioned side view of an improved and developed embodiment of the elevator machinery with an angle-compensated lifting nut and a load indicator.
• the eleva ⁇ tor machinery 2 comprises a screw 4 non-rotatably mounted in an elevator shaft (not shown) and having a center axis 5 and a steep lead angle (20-30 ) and a nut 6 with a corresponding lead angle, mounted on the threads of the screw.
• the nut is rotatably mounted in a housing 8 provided with a first brake means 7, preferably by means of a two-row angular contact bearing 9.
• the outer ring of the bearing is pressed into a bearing sleeve 12.
• the inner ring of the bearing is pressed onto the outer lateral surface of the nut and is in axial contact with an annular flange on a key 10 for a nut drive gear 14 of a second brake means 13.
• the bearing transmits axial forces acting from the elevator car and payload on the housing 8 to the nut 6 as well as taking up radial forces on the nut via a drive means fixed in the housing.
• the nut drive gear 14 cooperates with a drive device 16 comprising a transmission and a three-phase motor 20 controlled via a control unit 18 comprising a frequency converter.
• a drive device 16 comprising a transmission and a three-phase motor 20 controlled via a control unit 18 comprising a frequency converter.
• the transmission comprises suitably, in addition to the nut ⁇ drive gear 14, a drive gear 22 and drive means 24.
• Preferred transmission embodiments comprise a cogged belt transmission with drive gears in the form of cogged pulleys 14 and 22, and a drive means preferably comprising two parallel cogged transmission belts 24a,24b.
• the friction layer is suitably fixed to the flat housing end surface 32 facing the pulley.
• the opposite flat side 34 of the pulley is brought into contact with the fric ⁇ tion layer under the influence of gravity or, when horison- tally mounted, with the aid of a biasing spring (not shown) .
• the friction brake is hydraulically disengageable by activa ⁇ tion of the disengaging device via a hydraulic pump 36, which is controlled, together with the drive device by the common control unit.
• the disengaging device comprises an annular cylinder 38 and an annular piston 40, which are arranged in telescoping relation to each other. Between the cylinder and the piston there is enclosed an annular chamber 42, which communicates via a feeder channel 41 with the hydraulic pump.
• the annular chamber is sealed by conventional O-ring seals 43 disposed in the mutually telescoping cylindrical surface of the cylinder and the piston.
• a fall-stop nut 44 is disposed on the screw 4 beneath the elevator nut 6, said nut 44 following unloaded the movement of the nut 6 on the screw.
• the fall-stop nut is in this case disposed at a predetermined distance from the elevator nut, said distance corresponding to the maximum gap which can arise due to wear between the screw and the nut, before the elevator nut rests on the fall-stop nut.
• the fall-stop nut is driven along with the rotational movement of the elevator nut by means of at least one pin 46, which is fixed in the fall- stop nut and is insertable, parallel to the center axis 5 into a corresponding driver recess 48 in the elevator nut.
• the axial depth of the recess is adapted to the distance between the nuts.
• a dust protector sleeve 50 is mounted on ⁇ the fall-stop nut 44 and overlappingly covers the joint between the nuts, and has a flange 51.
• the control unit 18 re ⁇ ceives data values A on the operating state of the machinery via sensor elements 52 which are known per ⁇ e, and which can be mechanical, hydraulic, electrical, inductive, electro ⁇ mechanical or electro-optical.
• sensor elements 52 which are known per ⁇ e, and which can be mechanical, hydraulic, electrical, inductive, electro ⁇ mechanical or electro-optical.
• sensor elements 52 which are known per ⁇ e, and which can be mechanical, hydraulic, electrical, inductive, electro ⁇ mechanical or electro-optical.
• sensor elements 52 which are known per ⁇ e, and which can be mechanical, hydraulic, electrical, inductive, electro ⁇ mechanical or electro-optical.
• sensor elements 52 which are known per ⁇ e, and which can be mechanical, hydraulic, electrical, inductive, electro ⁇ mechanical or electro-optical.
• a pulse sensor 58 sees to it that the rpm of the nut does not exceed a predetermined value.
• Sensed values A are processed by the control unit 18 and are compared with predetermined values stored therein concerning e.g.
• Control signals B are then sent to the drive device 16 and the dis- engaging device 28. It is also possible, in response to these signals, to selectively control the drive device 16 and the disengaging device 28 in conjunction with each other by means of the control unit 18. This means that the electric motor can be started immediately prior to the activation of the disengaging device. The motor will thus provide a certain amount of torque while the friction brake 30 is still engaged and vice versa, to provide a gentle start and stop.
• FIG. 4 A further embodiment of the elevator machinery is revealed in Figure 4 and is in principle constructed in the same manner as that described above.
• the disengaging device 28' is in this case electromechanically instead of hydraulically operated.
• the device 28' is in the form of a bearing clutch 60, comprising two annular magnetic elements 62,64 arranged concentrically about the screw axis 5' and which in the rest position of the machinery are in contact with each other.
• One element is an electromagnet 62 , which is enclosed in an annular core 66 and has an annular coil 68.
• the magnet 62 has concentrically arranged, radially separated annular poles, e.g. a south pole 70 and a north pole 72.
• the poles face the other magnetic element, which is a permanent magnet 64.
• the poles 70,72 upon activation and depending on the polarisa ⁇ tion of the energizing current, are, relative to the center axis 5', an inner south pole 70 and an outer north pole 72.
• the permanent magnet 64 has radially separated permanently magnetized poles, a south pole 74 and a north pole 76, oppo ⁇ site the poles of the electromagnet 62.
• the south poles 70 and 74 and the north poles 72 and 76 repel each other, which causes the electromagnet to be lifted from the permanent magnet and, analogously to the annular cylinder shown in Figure 1, if there is a sufficiently strong activating cur ⁇ rent, the housing 8' will be lifted together with the equip ⁇ ment including the pay load mounted thereon.
• an air gap is formed between the magnets 62 and 64 , which permits the permanent magnet 64, which is fixedly joined to the elevator nut 6', to rotate together with the nut, via the drive device 16' with very low friction (the magnetic field) relative to the electromagnet 62 and the housing 8'.
• the magnets 62 and 64 thus constitute in this case an electromagnetic thrust bearing 9' .
• the annular portions of the magnets lie in contact with each other in the rest position, extend radially forming a right angle to the center axis of the screw.
• the contact surface between the portions is a frictional surface 25', which thus also forms a right angle to the screw axis. It is, however, advantageous if these portions are made so that the angle of the frictional surface to the screw axis is not a right angle and thus forms a truncated cone which can be turned upside down. This provides an advantageous self- centering effect in the magnetic bearing.
• the housing 8" of the elevator machinery together with a drive device 16", a mechanically operated disengaging device 28" and a friction brake 30" are fixed in the elevator shaft.
• a particularly simple and inex ⁇ pensive, vertically oriented elevator machinery, without any sophisticated control system, is achieved by means of the mechanical disengaging device for emergency lowering by virtue of the fact that the concave cone cooperates with a one-way clutch in the form of a free wheel 78.
• the elevator is operated upwards by means of the motor with the one-way clutch unblocked, while the operation downwards is done through gravity with a locked clutch (arrow A) .
• the main components of the disengaging device are a lever 80, a gimb- led pressure plate 82 and a thrust bearing 84.
• the dimension ⁇ ing and con-struction of the lever provides a mechanical advantage between the free end of the lever and its end acting against the pressure plate of about 60:1.
• a echanic- ally regulated centrifugal brake 86 ensures that the speed of lowering will not exceed a predetermined value.
• the centri ⁇ fugal brake 86 includes three brake shoes 88, each being pivotally mounted at one end with an individual pivot pin 90.
• Each brake shoe has a heel 92 which is suitably coated with a conventional friction layer. The heel is located circumferen- tially farther from the free end of the brake shoe than from the pivoted end.
• the disengaging device is easily actuated, e.g.
• a line 94 fixed to the free end of the lever which, as needed, e.g. when desending or during a power failure, is tensioned by lateral loading via one or more rotatable pulleys 96 travelling with the elevator car.
• Two pulleys are fixed to the elevator car, while one of the pulleys is movable relative to the others by means of an operating lever 98, to achieve the desired lateral load on the line.
• the operating force required on the handle 101 of the lever in order to, in this manner, unload the frictional surface between the cones, acts parallel to the force of gravity and is, as a rule, less than 10 N at a total load of 400 kg.
• the position of the operating lever shown with solid lines in Figure 7 is in its rest position in which the lever is held, for example by means of a spring arrangement (not shown) .
• a switch 103 is activated closing the circuit to the electric motor.
• the elevator has reached its desired position, the operating lever is released and it returns to its rest position, the switch breaks the circuit and the elevator stops.
• the eleva ⁇ tor is kept in this position by means of the free wheel and the brake means, which lock the rotation of the screw for descending, relative to the anchoring points in the elevator shaft.
• an upper limit switch 105 It is located at the uppermost portion of the elevator shaft and breaks the cur ⁇ rent circuit when the elevator car or a contact means mounted on the same strikes the corresponding means on the limit switch.
• the operating lever 98 When descending, the operating lever 98 is depressed from its rest position to the position shown with dashed lines in Figure 7, and the line 94 is tensioned by means of the pulleys 96. The line forces the free end of the lever 80 downwards. and its other end lifts, via the pressure plate 82 and the thrust bearing 84, the screw 4" with total load so far that the cone 7" lifts from the cone 13".
• the screw is then free to rotate due to the force of gravity in the nut and the elevator descends as long as the operating lever is kept in the position shown with dashed lines.
• the rate of descent is controlled by the centrifugal brake 86.
• the elevator stops since the screw with load again rests on the frictional surface 25" between the brake means and the rota- tion of the screw for descent is blocked by the free wheel 78.
• a dampening piston 107 is arranged at the bottom of the shaft and facilitates a gentle braking from the maximum descent rate permitted by the centrifugal brake, and standing still.
• the lower end of the screw is conical and is guided with a certain amount of play in a guide sleeve 109 provided with a brake cone and anchored in the bottom of the elevator shaft. If, despite the high safety requirements fulfilled by the elevator machinery described above, the screw should come loose above the elevator nut, the conical end of the screw will lie in contact with the brake cone in the guide sleeve 109, thus preventing uncontrolled rotation of the screw.
• the elevator machinery 302, ac ⁇ cording to an improved and developed embodiment shown in Figure 8 has a nut 306 mounted on a screw 304.
• the nut is, however, separated from the first brake means 307, the "nut housing” 308 and the angle contact bearing 309, as well as from the second brake means 313 and the nut gear 314.
• the nut is so located on the screw that the rest of the moving compo ⁇ nents of the machinery rest on the nut via an angle compensa- tor 315 mounted between the nut 306 and the gear 314, said compensator resting on the nut against a radial flange, which has three radially extending driver pins 316 evenly distri ⁇ ubbed about the periphery.
• the gear 314 has a driver housing 317 solidly joined to the same and having a cavity which cooperates with the driver pins 316 on the nut 306.
• the gear 314 is axially displaceable but non-rotatably connected to the nut.
• An annular piston 321 is sealingly fitted in the annular cylinder 319 by means of O-rings, and the chamber enclosed between cylinder and piston is filled with a fluid.
• the underside of the gear 314 is in contact with the annular piston 321, thus taking up angular deviations of up to 5 between the gear 314 and the nut 306, by the annular piston 321 "floating" on the enclosed volume of fluid and evenly distributing the contact pressure even if there are angular deviations.
• the nut gear 314 is mounted surrounding the bearing 309 which is pressed with its inner ring on the lower end of a tubular piston 323, which has at its upper end a piston flange 325 which is sealingly fitted by means of O-rings in a cylinder 327 in the housing 308, said cylinder serving as a pneumatic cylinder.
• the housing 308 has at its lower portion axially disposed pins (not shown here) which engage in corresponding holes in the annular cylinder (the brake means) 307.
• the brake means is thereby axially displaceable but non-rotatably connected to the housing 308.
• the axial displaceability is limited by the length of stroke of the piston 325.
• first brake means 307 which, in the rest position shown, is in contact with the second brake means 313, there is an annular chamber 329 in which an annular piston 331 is sea ⁇ lingly fitted by means of O-rings.
• the annular piston 331 is in contact on its top side with a shoulder on the underside of the housing 308 near the pin and the underside of said piston rests on a volume of fluid enclosed in the annular chamber 329.
• the first brake means 307 with the annular chamber 329 and the annular piston 331 thus form a load sensor 333.
• the annular chamber is connected via a conduit with a load sensor element 352, which converts the hydraulic pressure generated by the load in the annular chamber 329 into an output signal which is directed proportionally to the load.
• a load sensor element 352 of on/off-type is used sending signals at predetermined loads.
• the previously described protection against excess rotational speed can also be used for sensing the rotational direction of the nut 306 and its rotational position relative to the screw 304 by two pulse transducers 358 mounted in a known manner so that the pulses, which are sent synchronously with the rotation of the nut, are phased relative to each other.
• This provides a monitoring of both the rotational direction and the position as well as the rpm of the nut, and position ⁇ ing is made possible by corresponding turning of the nut in response to signals from the sensor elements.
• a signal is obtained which prevents con ⁇ tinued operation if the threads of the nut 306 should be worn out.
• the sensor elements 352, 354 and 358 are, as previously, connected to a control unit 318, and can provide, in each position of the elevator machinery, information on the cur ⁇ rent load and whether the contact pressure between the brake means is within the predetermined values, so that the braking effect is always assured.
• Automatic monitoring of the load sensor 333 is possible by programming the control unit 318 to register that the load sensor element 352 indicates a signal exceeding a certain value, e.g. 250 kg, if the empty weight of the elevator car including machinery is 300 kg or is less than another value, e.g.
• the control unit stops the operation. Excess load is indicated and starting is prevented if the elevator is loaded so much that a certain predetermined value is ex ⁇ ceeded.
• the load sensor 333 is dimensioned so that the brak ⁇ ing capacity is retained but stops continued operation if the indication should cease, due to leakage or wear. Wear should, however, not occur since the braking means in normal opera- tion is only actuated when the nut is stationary.
• the pulse transducers 358 were used for position and direction determination, they have as well, as was previously mentioned, a rpm monitoring function. If the drive system for some reason should fail in some way, so that the elevator will descend at too high a speed, it will be stopped when the rpm of the elevator nut 306 exceeds a predetermined value.
• the embodiment described above has a number of advantages over the previously described embodiments. Uneven loading of the nut is eliminated and bearing and other stresses are reduced. A more even operation is achieved which, i.a., reduces the risk of vibrations and noise. The efficiency is improved by correct contact in the thread flanks, which in turn means less wear on the nut threads. The unit is quite compact, is easy to install, and inexpensive to manufacture and is virtually service-free.
• a security-increasing effect is achieved by virtue of the fact that the screw is enclosed along its entire length below the nut in the channel formed between the elevator shaft and the elevator car. In the channel, the space for horizontal movement of the screw is limited, and therefore the screw can not buckle if a portion of the screw below the nut should be subjected to a compressive load.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Automation & Control Theory (AREA)
• Structural Engineering (AREA)
• Types And Forms Of Lifts (AREA)

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Cited By (7)

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Citations (4)

• 1992
  • 1992-12-18 SE SE9203827A patent/SE500708C2/sv not_active IP Right Cessation
• 1993
  • 1993-12-20 EP EP94903215A patent/EP0675848B1/en not_active Expired - Lifetime
  • 1993-12-20 WO PCT/SE1993/001091 patent/WO1994014695A1/en active IP Right Grant
  • 1993-12-20 DE DE69306413T patent/DE69306413T2/de not_active Expired - Fee Related

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