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
  • B66B9/04—Kinds or types of lifts in, or associated with, buildings or other structures actuated pneumatically or hydraulically

Definitions

• Hydrostatic drive for lifting and lowering and for holding loads, especially for lifts
• the invention relates to a hydrostatic drive for lifting and
• Such a drive is known from AT-PS 385 018, which is intended for lifting and lowering loads over great heights.
• the safety against kinking is to be improved by the fact that the end of the lifting piston protruding into the working cylinder slides sealingly on the guide rod.
• the large diameter of the massive piston which is otherwise necessary due to the buckling safety, is now being replaced by the ring-shaped end face that forms the working surface of the piston.
• the hollow piston because of the annular end face is not acted upon by the pressure medium on the inside.
• the entire lifting force is applied solely by the pressure medium located in the pressure chamber of the working cylinder, acting on the annular end face, which is supplied to the working cylinder with variable pressure during each lifting operation.
• the entire lifting force thus acts over the entire length of the piston.
• the wall thickness of the piston must be dimensioned accordingly.
• One disadvantage is that as the length of the reciprocating piston increases, the working area increases, the flow rate increases and a larger pump is required.
• the invention has for its object to improve a hydrostatic drive of the type mentioned so that the structural dimensions and thus the cost of materials can be reduced with the same good kink resistance. Furthermore, the connected load should be reduced and the working surface of the reciprocating piston should be kept constantly small regardless of its length.
• this object is achieved in that the interior of the reciprocating piston forms a further pressure chamber pressurized with pressure, to which a separate pressure medium source is connected, and that either the pressure medium source connected to the working cylinder has pressure medium with a substantially constant pressure and the pressure medium source connected to the further pressure chamber includes pressure medium a variable pressure, or vice versa.
• the interior of the reciprocating piston forms a further pressure space, a further working surface is created in the piston, the size of which is determined by the inner dimension of the annular end face.
• the total force required to lift the load can be broken down into two sub-forces, in the case of an elevator, for example, into a constant force that serves to lift the mass of the car, for example, and into a variable force that is used to lift the load in each case Car is used.
• the second partial force which acts on the other working surface close to the load inside the reciprocating piston, does not cause the reciprocating piston to buckle.
• the reciprocating piston can therefore be dimensioned for the stress caused by the first-mentioned smaller partial force, which in comparison with the known drive amounts to a reduction in the diameter and / or the wall thickness of the reciprocating piston.
• the material expenditure for the drive is therefore smaller than for the known one, which also reduces the manufacturing costs and requires a smaller pump for the smaller flow rate.
• Another advantage is that longer lengths of the reciprocating piston or slimmer working cylinders can be achieved with the same length of the reciprocating piston with the same working surface. This enables the number of different drive sizes to be kept in stock to be significantly reduced.
• the additional cylinder with the additional piston forming the pressure medium with a substantially constant pressure supplying pressure medium source.
• the additional piston under the influence of the counterweight, presses pressure medium with an essentially constant pressure into the corresponding pressure chamber of the drive, while the feed pump delivers pressure medium with variable pressure into the other pressure chamber of the drive.
• the energy inherent in the downward moving counterweight is used to lift a part of the load.
• a third pressure chamber is formed in the additional cylinder, a third working surface is created, the size of which depends on the size of the annular working surface of the reciprocating piston.
• the drive power can be reduced by up to 50% compared to the drive power for a drive with two feed pumps. By connecting the constant pressure on the pump suction side, the drive power can be reduced again by up to 50%.
• the counterweight is arranged on an additional cylinder which surrounds the working cylinder in a sealing manner, forming a pressurized space, this room being connected to the pressure chamber of the working cylinder and to form the pressurized space of the working cylinder on its outside is gradually reduced in diameter.
• Fig. 1 shows a longitudinal section through a hydrostatic drive with two pressure chambers, each connected to its own pressure medium source, and
• the hydrostatic drive has a hollow reciprocating piston 1, which is closed at its upper end by an end wall 2.
• the lower end 3 of the vertically arranged reciprocating piston 1 is somewhat thickened on its inside and on a guide rod 15 slidably guided, which is fastened with its lower end 16 in a base plate 20 of a working cylinder 10.
• a mechanical seal 4 is embedded in the lower end 3 of the reciprocating piston 1, so that the interior 7 of the reciprocating piston 1 is tightly separated from the inside of the working cylinder 10.
• the upper end 11 of the working cylinder 10 is also thickened on the inside and provided with a mechanical seal 12 which bears on the outside of the reciprocating piston 1. In this way, the reciprocating piston 1 is guided sealingly in the working cylinder 10.
• a bore 21 is provided in the base plate 20 of the working cylinder 10, to the outside of which a pressure medium line 23 is connected, which comes from a pressure medium source 30 which supplies pressure medium with a substantially constant pressure P2.
• the bore 21 opens into the interior of the working cylinder 10, which delimits a pressure chamber 13.
• a further bore 22 is provided in the base plate 20, to the outside of which a pressure medium line 24 is connected, which comes from a second pressure medium source 40 in the form of a feed pump that supplies pressure medium with variable pressure P 1.
• the upper end of the bore 22 opens into an axial channel 17 provided in the guide rod 15, which opens at its upper end 18 into the interior 7 of the reciprocating piston 1.
• the pressure source 30 consists of a feed pump 32 driven by an electric motor 31, which sucks pressure medium from a tank 39 and delivers it via the pressure medium line 23 into the pressure chamber 13 of the working cylinder 10.
• a valve 33 which can be a switching or proportional directional control valve which shuts off the pressure medium flow in the position shown and allows pressure medium to flow through to the pressure chamber 13 in another position.
• an overflow line 35 with an overpressure valve 35 branches off from the line 34 and leads back into the tank 39.
• Feed pump 42 is also driven by an electric motor 41 and draws in pressure medium from a tank 39.
• a valve 43 is arranged in its line 22, which can be a switching or proportional directional valve, which, analogous to valve 33, has two Can take end positions.
• An overflow line 45 with an overpressure valve 46 is also present in the feed pump 42 analogously to the feed pump 32.
• the feed pump 42 delivers pressure medium with a variable pressure Pl into the interior 7 of the reciprocating piston 1.
• a spacer ring 25 is attached as required, which is suspended via flexible tension elements 26, for example wire cables, at the lower end 3 of the reciprocating piston 1.
• a further spacer ring 25 'as required is attached in the same way below the spacer ring 25, which still rests on the base plate 20 in the drawn position of the reciprocating piston.
• the spacer rings 25 and 25 ' serve to prevent the guide rod 15 from buckling. They slide up and down with the reciprocating piston 1, the spacer ring 25 being able to rest on the spacer ring 25 'in the lowest position of the reciprocating piston.
• the reciprocating piston 1 is also distributed over its length with one or more spacer rings 27 as required, which slide on the guide rod 15 when the reciprocating piston moves and serve as protection against buckling of the reciprocating piston.
• the pressure medium with the pressure P2 in the pressure chamber 13 of the working cylinder 10 acts on an annular end surface 5 at the lower end 3 of the lifting piston 1.
• the end surface 5 forms an annular working surface A2, as shown on the right in FIG. 1.
• the interior 7 of the reciprocating piston 1 forms a further pressure chamber, in which the pressure medium of the pressure medium source 40 acts with the variable pressure P1.
• a further work surface 6 is therefore formed on the end wall 2, the size of which is determined by the inner diameter of the work surface A2. It is shown separately in FIG. 1 on the right as a circular area AI.
• a throttle rod 60 is attached, which is coaxial with
• Channel 17 is arranged in the guide rod 15.
• the lower half of the throttle rod 60 is slightly tapered downwards. It forms when the reciprocating piston 1 moves downward whose last movement section of about 1 m in length when immersed in the channel 17 together with a throttle point. This dampens the downward movement of the reciprocating piston.
• a pipe rupture safety valve 68 and 69 are provided, which serve as a throttle in the event of a pressure medium line break 23 and 24.
• the pressure medium with the pressure P2 of essentially constant size continuously generates a constant lifting force on the working surface A2, which is approximately so large that, depending on the need, e.g. corresponds to approximately 90% of the mass of a car of an elevator supported on the upper end of the lifting piston 1.
• This part of the mass is indicated in FIG. 1 by the arrow F2.
• the pressure medium with the variable pressure Pl which acts on the further working surface AI, generates a variable lifting force that the remaining part of the load to be lifted, i.e. corresponds to approximately 10% of the mass of the car, the piston and the people in the car.
• This part of the load is indicated in Fig. 1 by the arrow FI.
• valves 33 and 43 are brought into the blocking position in the pressure medium line 23 and 24, respectively, so that the elevator car stops.
• these valves are opened, and under the influence of the weight forces FI and part of the weight force F2, the pressure medium is returned from the pressure chambers 7 and 13 via the lines 23 and 24 into the tank 39, the two feed pumps 32 and 42 turn along.
• the feed pumps 32 and 42 are switched on in order to reclaim the pressure medium from the pressure chambers 7 and 13 via the lines 23 and 24 into the tank 39.
• these valves are also opened.
• FIG. 2 is the drive consisting of the reciprocating piston 1, the working cylinder 10 and the guide rod 15 constructed in the same way as in FIG. 1.
• a vertical additional cylinder 50 is provided in FIG. 2, in which an additional piston 55 is sealingly guided.
• a counterweight 57 is attached to the additional piston 55; which corresponds to approximately 90% of the mass of the car 62 supported on the reciprocating piston 1.
• the mass is denoted by M.
• the underside of the vertically arranged additional piston 55 forms a third working surface 56, the size of which is shown separately to the left of the additional piston 55 in FIG. 2 and is designated A3.
• In the bottom 53 of the additional cylinder 50 there is a bore 57 which connects to the bore 21 via a pressure medium line 23
• Working cylinder 10 is connected and presses the pressure medium from the pressure space 54 under the working surface 56 into the pressure space 13 of the working cylinder, with the constant pressure P2.
• the feed pump 42 which supplies pressure medium with variable pressure, is in turn connected to the bore 22 via the pressure medium line 24.
• An overflow line 45 branches off between the feed pump 42 and the valve 43, which leads to the tank 39 and which can be seen with the pressure relief valve 47 and a suction valve 46.
• the feed pump 42 is connected to the pressure medium line 23 via a line 64.
• the line 64 contains a valve 63 which corresponds to the valve 43 in its construction.
• An overflow line 65 branches off from the line 64 between the feed pump 42 and the valve 63 and contains a valve 66 and 67 corresponding to the valves 46 and 47 and leads to the tank 39.
• the tank 39 for the pressure medium can be dimensioned much smaller, since a large amount of the pressure medium is absorbed by the additional cylinder 50.
• the drive power can be reduced by up to 50% depending on the size ratio of the third work surface A3 to the annular work surface A2.
• a further reduction in the drive power is achieved in that, in the example according to FIG. 2, the suction side of the feed pump 42 is connected to the pressure medium line 23 via the line 64, so that the feed pump 42 is supplied with pressure medium of constant pressure P2 and only the pressure increase from P2 to Pl must generate.
• the constant pressure-supplying pressure source is integrated with the working cylinder, so that a compact, space-saving design results.
• the working cylinder 10 is reduced in the outer diameter in its upper section 10 "and has a step-shaped transition to the larger outer diameter in the lower section 10" "" .
• the upper reduced section 10 ′′ is surrounded in a sealing manner by an additional cylinder 70, on the outside of which the counterweight 57 ′′ is attached.
• the upper end 71 of the additional cylinder 70 is thickened toward the upper reduced section 10 "of the working cylinder 10 and abuts the upper section 10" of the working cylinder 10 via a mechanical seal 72.
• a mechanical seal 74 is also provided at the lower end 73 of the additional cylinder 70 and bears against the lower thickened section 10 "" of the working cylinder 10.
• Section of the working cylinder 10 a plurality of through holes 76 are provided which connect the pressure chamber 13 of the working cylinder 10 to a pressure chamber 75, the upper end face 77 of which has an annular shape and is limited by the inside diameter of the additional cylinder 70 and the reduced outside diameter of the cylinder section 10 ".
• the same diameters also limit an annular working surface A3 on the right in FIG. 3, which is formed by the thickened upper end of the additional cylinder 70.
• the feed pump 42 is installed in the base plate 20 'of the working cylinder 10. It is connected to the bore 23 with its suction side and to the bore 21 with its pressure side. On the suction side and on the pressure side of the feed pump, a valve 43 or 63 is provided, designed as a switching or proportional valve, arranged to open and close the line in question.
• valves 43 and 63 are opened and the additional cylinder 70 slides downward under the influence of the counterweight 57 "on the working cylinder 10.
• the pressure medium located in the pressure chamber 75 is displaced with the pressure P2 via the holes 76 into the pressure chamber 13 of the working cylinder 10.
• the pressure medium acts on the one hand on the working surface A2 at the lower end 3 of the reciprocating piston 1 and lifts it, on the other hand pressure medium reaches the suction side of the feed pump 42 via the bore 21 and is conveyed by the latter with the pressure Pl into the interior 7 of the reciprocating piston 1.
• This part of the pressure medium acts on the working surface AI and supports the upward movement of the reciprocating piston 1.
• the reciprocating piston 1 presses the pressure medium from the interior 7 via the channel 17 of the guide rod 15 and the feed pump 42 to the interior 13 of the working cylinder 10. This space then becomes the pressure medium is pressed through the holes 76 into the pressure chamber 75, the additional piston 70 being moved up again into the upper position shown in FIG. 3.
• the valves 43 and 63 are in the closed position.
• the embodiment according to FIG. 4 is modified compared to that according to FIG. 3 in that the working cylinder 110 is divided into two sections 110 "and 110""which are axially displaceable relative to one another, the upper section 110" having a shape similar to that of the additional cylinder 70 in Fig. 3.
• the upper cylinder section 110 is also thickened at its upper end 111 and provided with a mechanical seal 112. It slides with this end on the reciprocating piston 1.
• the lower end 111 of the cylinder section 110" is sealed to the fixed lower section 110 ""of the working cylinder 110, for which purpose a mechanical seal 112 is provided in the thickened end 111 of the upper cylinder section 110".
• a pressure chamber 75" is enclosed, which is at the upper end of the end wall 11 "is limited, which forms the annular work surface A3.
• the counterweight 57 "" is in turn attached to the outside of the upper cylinder section 110 ".
• the feed pump 42 is of the same design and is installed in the base plate 20""as in the example according to FIG. 3. Accordingly, the mode of operation is also the same as that of FIG. 3 described, ie when lifting the load presses the upper one
• Cylinder section 110 under the influence of the counterweight 57" "pressure medium with the constant pressure P2 into the pressure chamber 13 of the working cylinder 110, as a result of which the reciprocating piston 1 is raised.
• pressure medium passes from the pressure chamber 13 via the bore 23 to the feed pump 42, which it carries with it supplies the variable pressure Pl into the further pressure chamber 7 of the reciprocating piston 1.
• This pressure medium acts on the further working surface AI and supports the upward movement of the reciprocating piston.
• the pressure medium from the pressure chambers 7 and 13 is limited to that of the upper cylinder section 110 " Pressure chamber 75 "pressed, the pressure medium being first displaced from the pressure chamber 7 via the feed pump 42 into the pressure chamber 13 before it reaches the pressure chamber 75 '.
• the pressure medium can have an essentially constant pressure supplies, a bladder accumulator or a piston accumulator can be used.
• the pressure sources connected to the pressure chambers 7 and 13 can also be interchanged, ie pressure medium with constant pressure is supplied to pressure chamber 7 and pressure medium with variable pressure is supplied to pressure chamber 13.
• the drive described can not only be used for elevators; it can also be used, for example, for carriages that can be moved up and down on machine tools, lifting platforms for cranes, forklift trucks, lifting platforms, active car and truck shock absorbers, etc.
• one, two or more than two spacers 25 and 25 "and 27 can be provided as required, which are then fastened at a corresponding mutual distance in the reciprocating piston 1 or are attached to one another via cables 26.
• the suction line of the feed pump 42 can be connected to the line 34 instead of to the tank 39, as is the case in an analogous manner in the other examples, the counterweight 57 can be attached directly or with ropes to the additional piston or additional cylinder
• the electric motor can be connected to a frequency converter and this to an electronic control card which then supplies control signals to the frequency converter and the valves.
• the valves are provided as switching or proportional directional valves, which also can be controlled with pulse modulated signals. Only one valve can be used for drives be installed in the pressure medium line 23 or 24.
• the filters can be installed in the two pressure medium lines 23 and 24, or only in one pressure medium line 23 or 24.

Landscapes

• Engineering & Computer Science (AREA)
• Automation & Control Theory (AREA)
• Structural Engineering (AREA)
• Actuator (AREA)
• Types And Forms Of Lifts (AREA)
• Forklifts And Lifting Vehicles (AREA)
• Load-Engaging Elements For Cranes (AREA)
• Details Of Reciprocating Pumps (AREA)
• Fluid-Pressure Circuits (AREA)

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• 1997
  • 1997-04-30 CH CH01004/97A patent/CH689211A5/de not_active IP Right Cessation
• 1998
  • 1998-04-28 AT AT98914771T patent/ATE233374T1/de not_active IP Right Cessation
  • 1998-04-28 CN CN98804673A patent/CN1096577C/zh not_active Expired - Fee Related
  • 1998-04-28 DE DE59807321T patent/DE59807321D1/de not_active Expired - Fee Related
  • 1998-04-28 TR TR1999/02647T patent/TR199902647T2/xx unknown
  • 1998-04-28 JP JP54645198A patent/JP2001527497A/ja not_active Ceased
  • 1998-04-28 EP EP98914771A patent/EP0979357B1/fr not_active Expired - Lifetime
  • 1998-04-28 AU AU69169/98A patent/AU6916998A/en not_active Abandoned
  • 1998-04-28 WO PCT/CH1998/000173 patent/WO1998049085A2/fr not_active Ceased
  • 1998-04-28 ES ES98914771T patent/ES2189153T3/es not_active Expired - Lifetime
  • 1998-04-28 PT PT98914771T patent/PT979357E/pt unknown
  • 1998-04-28 BR BR9809430-0A patent/BR9809430A/pt not_active IP Right Cessation
• 1999
  • 1999-10-29 US US09/432,059 patent/US6422349B1/en not_active Expired - Fee Related

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