Chain drive assembly and lifting mechanism with double chain wheel

Abstract

A lifting device with an electric or pneumatic motor and two link chains has two sprockets (R11, R12) arranged side by side on a shaft (d) driven by the motor. Each sprocket serves to guide a section of a link chain with alternating horizontal (L) and vertical (T) links, namely with pockets for receiving horizontal links and with a circumferential groove for receiving vertical links. The sprockets (R11, R12) are arranged in a rotationally fixed position relative to each other at the same angular orientation, in which the angular pockets of the two sprockets are offset from each other by only a distance parallel to the shaft, but are not rotated relative to each other.

Description

[0001] The invention relates to a hoist with a doubled chain wheel, in which more than one link chain is used as a support means. In particular, the invention relates to a chain drive arrangement with a chain drive on a chain drive shaft that is drivable by a motor, wherein at least two link chain strands can be guided via the chain drive, as well as to a hoist device in which such a hoist device is connected to a motor directly or via a gear. The invention further relates to a hoist system that includes a hoist device and link chain strands guided via the chain drive of the hoist device, and a stop device that can be attached to the ends of the link chain strands.

[0002] In lifting devices (this term encompasses chain drive arrangements, lifting device equipment, and systems) of the type under consideration here, link chains—in particular industrial round steel chains or profile steel chains—are used as load-bearing means for lifting and / or moving loads. The chain links of a chain strand are guided over a sprocket (also referred to as a chain sprocket), with the links of the chain strand being oriented alternately in a vertical and horizontal position on the outer surface of the sprocket. Advantageously, the chain drive comprises two sprockets arranged side by side on a shaft of the chain drive, with each of the sprockets being designed to guide a respective section of a link chain strand with alternating horizontal and vertical links, namely with pockets for accommodating horizontal links and with a circumferential groove for accommodating vertical links.

[0003] For lifting gear and sling devices, the load-bearing capacity and safety against chain breakage are naturally of particular importance. If, for example, the load-bearing capacity of motor- or manually operated hoists needs to be doubled, the chain drive arrangement in the hoist with a single chain strand can be converted to a two-strand version of the link chain based on the pulley principle, e.g., with a deflection pulley for deflecting the chain. Multiple strands can also be designed to triple or multiply the load-bearing capacity. The disadvantage of this is that the chain must also be guided over deflection pulleys when under full load. With a two-strand chain drive arrangement, this leads to a tripling of the loaded chain deflections on the involved sprockets in each lifting cycle (once on the drive sprocket and twice on the deflection sprocket).This leads to a significant reduction in the service life of the chain, which is practically cut in three. Likewise, the lifting speed of multi-strand chain drive arrangements is reduced inversely to the number of strands. The inventors recognized the often considerable space required by the sprockets as a further disadvantage.

[0004] To remedy these disadvantages, the invention proposes that, in a chain drive arrangement, the chain drive has two or more sprockets arranged side by side in a rotationally fixed manner on a shaft of the chain drive, with the two sprockets arranged at the same angular position relative to each other. In this same angular position, the angled pockets of the two sprockets are offset from each other by only a distance parallel to the shaft.

[0005] This inventive solution offers several advantages. By using a double (or multiple) sprocket and a correspondingly multiplied chain, the load of the lifting mechanism can be doubled or multiplied (without additional chain deflections per chain), and the negative impact on chain service life is avoided. The invention also enables the use of chains with smaller chain links and sprockets with smaller diameters. The possibility of using a smaller-sized chain (with the same load capacity per chain) is also advantageous in terms of chain service life. Smaller chain dimensions offer advantages over larger chains in terms of wear life, as they improve the ratio of chain surface area to chain volume.

[0006] In a chain drive with a doubled sprocket, the diameter of the chain used can be reduced by a factor of √2 (equivalent to two chains with half the load capacity) while maintaining the same total load capacity. This also reduces the required chain pitch and the size of the sprocket by the same factor. Thus, with the same load capacity, the double chain drive can be reduced in diameter by a factor of 1 / √2 = 0.71 compared to a chain drive with a single chain.

[0007] By reducing the chain wheel size, the drive torque required in the associated lifting device can also be reduced by this factor. This means that the chain drives in the lifting device can be made smaller overall. Consequently, a lower drive torque is required, and thus the weight of the double-chain drive can be reduced compared to a single-chain drive for the same load. The linear dimensions of the chain drive are thus reduced by approximately 11% (according to the cube root of 0.71). The weight and size savings of the chain drive and the lifting device as a whole also result in considerable savings in terms of costs and materials.

[0008] A further advantage is increased safety against chain failure, especially chain breakage, by using two or more parallel chains. Should one chain fail (break), the load will not fall; the other chain can still carry the load—for example, if designed with a 4x safety factor.

[0009] In an advantageous development of the invention, the hoist device is also equipped with a motor that is connected to the chain drive shaft directly or via a gear. This offers particular advantages, especially for compact, machine-operated hoists used in lifting systems such as cranes. For these hoists and the systems in which they are installed, not only is the more compact design advantageous, but also that other components such as the gearbox or braking device (safety brake) can be designed smaller, since, with a constant load capacity, the dimensioning of a single chain strand can be taken into account (instead of the design of the chain hoist as a whole). Thus, the dimensioning of the motor, as well as any associated gearbox and / or braking device, can correspond to the size of an individual link chain strand.This applies in particular if the motor is electrically or pneumatically operated.

[0010] In particular, replacing the (single) sprocket with a double sprocket allows the chain size (size of the chain links) and the sprocket to be smaller while maintaining the same load capacity of the compact hoist. The smaller diameter of the sprocket results in lower torques. This subsequently enables smaller dimensions for the brake (safety brake), the motor gearbox, and ultimately also the motor (with the same power but higher speed). Furthermore, a smaller housing can be provided, resulting in overall weight savings. Overall, the invention leads to considerable cost savings, especially for motor-driven hoists.

[0011] Conveniently, the sprockets can be arranged directly next to each other on the shaft and preferably constructed as a single piece, and / or the sprockets can be spaced apart from each other on the shaft. A particularly advantageous configuration is a chain drive with two sprockets. These can be mirror-symmetrical to each other.

[0012] To improve the guidance of the chains over the sprockets, a housing is advantageous that surrounds the sprockets and limits the radial movement of the chain links on the sprockets. It can be advantageous if the housing has two grooves on the inside, side by side, in which the stationary links of the link chain strands running on the sprockets are guided.

[0013] The aforementioned advantages also arise in particular for a lifting device system which, in addition to a lifting device of the type mentioned above, is provided with link chain strands guided via the chain drive of the lifting device and with a lifting device attached to the ends thereof, which has two adjacently arranged connection points for one end link of each link chain strand and, on a side facing away from the link chain strands, a connecting part for a load, wherein the connection points are arranged at the same height with respect to a load direction (i.e. parallel to the direction of travel of the link chain strands). Advantageously, the connecting part can comprise a load hook. This can be mounted on the lifting device so as to be rotatable about an axis parallel to the load direction.

[0014] The invention, including further details and advantages, is explained in more detail below with reference to several exemplary embodiments illustrated in the drawings, all of which are merely exemplary and not limiting of the invention. The drawings schematically show: Fig. 1 shows a lifting system with an electric motor according to a first embodiment of the invention in a side view ( Fig. 1a ) and a front view ( Fig. 1b ); Fig. 2 a hoist system with a conventional single chain wheel; Fig. 3 a perspective view of a chain drive system with a double chain wheel and a stop device, which is used in the hoist of the Fig. 1 can be used; Fig. 4 the double chain wheel of the Fig. 3 in a front view ( Fig. 4a ), a longitudinal section view ( Fig. 4b ) and a sectional view of a sprocket along the center plane ( Fig. 4b ); Fig. 5the chain drive system of the Fig. 3in a supervision ( Fig. 5a ), a front view ( Fig. 5b ) and a side view ( Fig. 5c ); Fig. 6the chain drive of the Fig. 4 together with a housing surrounding the sprockets, in a front view ( Fig. 6a ), in a longitudinal section view (Fig. 6d) and in a section view along the center plane of one of the sprockets ( Fig. 6c ); and Fig. 7 shows a lifting system with a pneumatic motor according to a further embodiment of the invention in a side view ( Fig. 7a ) and a front view ( Fig. 7b ).

[0015] For reasons of clarity, identical elements are provided with the same reference numerals in the figures. The reference numerals in the claims are intended solely for clarity and in no way represent a limitation to the respective embodiments. The drawings show exemplary embodiments in which - without this being construed as limiting the invention - a load is carried against the force of gravity, and thus the load direction b (see Fig. 1 and 3) corresponds to the vertical; however, it is obvious that in other applications the load direction can also be oriented differently, such as when transporting a load along a track, in which case the load direction usually corresponds to the direction of travel. Generally speaking, the chains used as load-bearing devices in the chain hoist run essentially symmetrically along the load direction when under load. Terms such as "upper area," "lower," or "underside" are to be understood in this sense, namely in relation to an orientation according to a vertically conceived load direction.

[0016] The exemplary embodiments presented below relate to chain drives designed for round steel chains, in which the individual chain links are rotated 90° relative to each other around the direction of the chain. The chains can also be chain links of other shapes, such as profile steel chains, and the person skilled in the art can readily make the appropriate adaptations to the sprockets and chain drive systems according to the invention for chains of these types. The chains are generally made of steel, such as case-hardened steel, but tempered steel can also be advantageously used.

[0017] If a link chain is guided over a sprocket of a chain drive according to the invention, the individual chain links are alternately vertical T and horizontal L (see e.g. Fig. 3 and 4a) on the respective sprocket and thus guided. The terms "vertical" and "horizontal" have the meaning already commonly used in the prior art: A vertical chain link T is a chain link that is supported by (only) one leg. The eye of a chain link standing on the sprocket is oriented essentially parallel to the sprocket's axis of rotation. On a sprocket, this leg of the vertical chain link is often located in a circumferential groove of the sprocket, which determines the position of the chain link. A horizontal chain link L is a chain link whose two legs rest next to each other. The eye of a horizontal chain link on the sprocket is oriented essentially radially with respect to the sprocket's axis of rotation. The sprockets considered here generally have chain pockets, each of which accommodates a horizontal chain link.

[0018] In Fig. 11 shows a lifting system 10 according to a first embodiment of the invention. The lifting system includes a chain drive system with a double chain 11 and a double sprocket 12 according to the invention, as discussed in detail below, as well as an electrically driven motor 13, which, via a gear 14, drives the shaft 15 for driving the chain drive system 11, i.e., the shaft on which the double sprocket of the chain drive system 11 is arranged. A connecting cable 19 serves to supply electricity to the electric motor 13.

[0019] The motor 13, the gearbox 14, and the upper part of the chain drive system 11 (in particular, the double chain wheel 12) are housed in a housing 16, which is open at the bottom, at least in the area of ​​the chain drive. The housing 16 can be held and positioned at its upper side, for example, by means of a mounting hook 17 permanently mounted thereon on a support or crane boom (not shown). The lifting system 10, and in particular the operation of the electric motor 13, are controlled and monitored in a conventional manner, e.g., via a manual control unit 18.

[0020] Fig. 3 is a perspective view of an embodiment of a chain drive system K, which is used in particular as a chain drive system 11 in the system of Fig. 1The chain drive system K contains a chain drive in the form of a double chain wheel D1 together with two chain strands S11, S12 of a chain hoist guided on it, at the ends of which a stop device A1 is also attached. As shown in Fig. 3 The two chain strands S11, S12 are each guided around one of the two chain wheels R11, R12 of the double chain wheel D1, with the individual chain links being held and guided alternately in a vertical position T and in a horizontal position L on the respective chain wheel R11, R12.

[0021] In Fig. 2 For comparison, a lifting system 20 of a conventional type with a single chain 21 and a chain wheel 22 is shown. Since in this case the load to be lifted is held and moved by a single chain, the chain 21 is dimensioned accordingly; the dimensioning of the motor 23 and gearbox 24 follow the dimensioning of the chain 21. In contrast, the two chains 11 of the lifting system 10 of the Fig. 1 can be designed smaller, since the load to be lifted is distributed across two chain strands. This also allows for a smaller design of the gearbox 14 and possibly also of the motor 13. This results in an overall smaller and more economical design of the lifting mechanism system 10, with less space required – smaller housing 16 – and a lower weight of the lifting mechanism compared to previous lifting mechanisms. Furthermore, the multiple chain design results in increased safety against chain strand breakage due to the redundancy of the chain strands.

[0022] For example, a chain drive with a double sprocket could have a technical design as shown in Table 1 compared to a conventional chain drive with a single sprocket: Table 1 Simple chain drive (state of the art) Chain drive with double sprocket Chain size dxt [mm] 10 x 30 7,1 x 21,3 Chain load capacity [kg] 2000 1000 Sprocket size, pitch circle, z=5 [mm] 97,1 68,9 Drive torque on the chain drive [%] * 100 71 Weight saving of the chain drive system [%] * 0 29 Size savings (linear dimension) [%] * 0 11,0 *) compared to the simple chain drive (column 2 / Fig. 2 )

[0023] Fig. 4 shows further details of the sprockets of the chain drive (double sprocket D1) of the Fig. 3 without inserted chain links. Fig. 4a a front view, Fig. 4b shows a longitudinal section view along a section plane through the rotation axis d of the chain drive, and Fig. 4c shows a sectional view of a sprocket R11 along the median plane m1 (viewing direction along the rotation axis d); this corresponds entirely to a sectional view of the other sprocket R12 along the median plane m2.

[0024] In Fig. 5 The chain drive system K is shown in three further views ( Fig. 5a-5c ), namely in a top view ( Fig. 5a ; View along the load direction b), a front view ( Fig. 5b ) and a side view ( Fig. 5c ; Viewing direction parallel to the rotation axis d of the chain wheel). Fig. 3 to 5The chain drive is shown without the housing so that the chain wheel and the chain strands guided in it are more clearly visible; the housing E1 is optional and is described below using the Fig. 6 explained.

[0025] Referring to Fig. 4a-4c Each of the sprockets R11 and R12 is designed as a so-called pocket sprocket. It therefore has pockets H that are adapted to the oval link shape and provide a substantially flat support surface (pocket bottom) for each horizontal chain link L (see Fig. 5a). In the longitudinal center of the pockets, recesses can also be formed if necessary, which serve to accommodate any welding bead (not shown) around a leg of the chain link, so that a horizontal chain link L can lie flat on the support surface of the pocket H even if such a welding bead is present. The pockets of the chain wheel are delimited from one another by webs G, each web being divided by a groove F for receiving the vertical links T in the center plane m1, m2 of the chain wheel R11, R12, so that a web G is divided into two teeth Z (to the left and right of the center plane m1 and m2 respectively).In the present embodiment, the sprocket has a pentagonal shape in side view (number of pockets z=5), with five pockets H and, accordingly, five webs G that delimit these pockets; however, it is clear that a sprocket can easily have a larger or smaller number z of pockets and webs. The webs G have convex flanks that, at their "inner" edge (i.e., closest to the rotation axis d), merge directly into the flat contact surfaces of the pockets H, preferably with a pronounced transition edge.In the preferably flat bottom of the grooves F for the upright links T, an additional recess can be cut out between the teeth Z, which serves the same purpose as the above-mentioned recess in the pocket bottom, namely to accommodate any welding bead (not shown) of the upright link T, so that the flat outer side of its inner leg can rest or support itself flat on the groove bottom. The support of the upright links T on the groove bottom of the groove F is of great importance for the function of the chain drive or wheel, since the horizontal links L in turn support themselves on the upright links T during the pivoting process, which makes it easier for the horizontal chain links to pivot onto the respective pocket bottoms in the correct position.Due to this design of the sprocket, both the horizontal links L and the vertical links T are supported flatly, namely the horizontal links L with a large part of their side surfaces on the support surface of the pockets and the vertical links T with the outer surface of the inner leg on the groove bottom.

[0026] In the double chain wheel D1, the two chain wheels R11, R12 are connected to one another coaxially and rotationally fixedly. According to the invention, the chain wheels are arranged to one another without any relative angular offset, i.e. the chain pockets of one chain wheel R11 are located directly next to the chain pockets of the other chain wheel R12, as viewed along the axis of rotation d. This can also be applied equivalently to the webs G, i.e. the webs G of one chain wheel R11 are located directly next to the webs G of the other chain wheel R12, as viewed along the axis of rotation d. According to another point of view, the two chain wheels R11, R12 can also be viewed as being symmetrical to one another about the center plane m0. The two chain wheels are, for example, designed as a single piece in the double chain wheel D1; alternatively, they can be designed as separate components R11 and R12, which are connected to one another in a rotationally fixed manner in a suitable manner, e.g.by means of connecting pins or by welding.

[0027] Referring again to Fig. 1-3 The load (not shown) to be carried by the hoist is connected to the ends of the two chains S11, S12 by means of a sling device A1, each of which has a connection point for the chain strands, these connection points being arranged at the same height along the load direction. The sling device A1 comprises a sling component C1 with a load hook B1. The sling component C1 is formed by a sleeve-shaped body with connection points C11, C12 provided in its "upper" area. Using these connection points C11, C12, which are provided inside the body, the respective end links of the chain strands are inserted and fastened, for example, with a bolt (not shown).

[0028] The load hook B1 is mounted in the "underside" of the body of the stop component C1, preferably rotatable about an axis parallel to the load direction b. In one variant, however, the load hook B1 can be non-rotatably attached to the body of the stop component C1.

[0029] In general, the stop device has, on the side opposite the connecting part, two (or possibly more) connection points arranged next to one another for one end link of each link chain, wherein these connection points are preferably arranged at the same height as seen in the load direction.

[0030] Fig. 6 shows an example of a lifting mechanism arrangement W2 in which the double chain wheel D1 is rotatably mounted in a chain drive housing E1 (the components for holding the housing are shown in Fig. 6 omitted for clarity). Fig. 6a a front view; Fig. 6bshows a longitudinal sectional view along a "horizontal" section plane 6-6 through the rotation axis d of the double chain wheel D1; and Fig. 6c shows a sectional view along the center plane m1 of the sprocket R11. The housing E1 surrounds the sprockets R11, R12 and limits the radial movement of the link chains on the sprockets. The double sprocket D1 is concentrically mounted in the housing E1 by the shaft (which runs along the rotation axis d) and its holders (not shown), so that the wheel D1 can rotate in the housing E1 without touching it and is simultaneously rotatably held therein. As can be seen particularly in the sectional view of the Fig. 6bAs can be seen, the housing has two grooves F1, F2 on the inside, side by side, in which stationary links of the link chains running on the sprockets are guided. An inner part J2, also referred to as a scraper, can also be provided, which closes off the chain drive on the output side and can also guide the chain sections as they enter the chain drive and, in particular, as they detach ("strip") the chains from the sprockets and exit the chain drive. The housing E1 and the inner part J2 are held, for example, in the motor housing.

[0031] A further exemplary embodiment of the invention is shown in Fig. 7, which represents a pneumatically operated lifting system 70. This lifting system 70 also includes a chain drive system with a double chain 11 and a double chain wheel 12 according to the invention, but a motor 73 driven by compressed air, which is controlled and monitored, for example, by a manual control unit 78 and is pneumatically supplied via a compressed air line 79. The pneumatic embodiment is characterized by additional space and weight savings of the motor 73 and gear 74, so that the housing 76 is also even more compact. Otherwise, this embodiment corresponds to the one described above with reference to the Fig. 1 and 3-6 explained embodiment.

[0032] Naturally, those skilled in the art will be able to modify the invention in light of the illustrated embodiments and the description and adapt it to given requirements. The technical structure of the invention is therefore not limited to the illustrated embodiments; rather, the invention extends to the entire scope of protection resulting from the following claims.

Claims

1. Chain drive arrangement with a chain drive (D1) on a chain drive shaft which can be driven by a motor, wherein at least two link chain strands (S11, S12) can be guided via the chain drive, wherein the chain drive has at least two sprockets (R11, R12; R61, R62) which are arranged next to one another on a shaft of the chain drive, and each of which is designed to guide a section of a link chain strand with alternating horizontal (L) and vertical (T) links, namely with pockets (H) for receiving horizontal links and with a circumferential groove (F) for receiving vertical links, wherein the two sprockets (R11, R12; R61, R62) are arranged in a rotationally fixed manner to one another in the same angular position, in which the angular pockets of the two sprockets are offset from one another by only a distance parallel to the shaft.

2. Chain drive arrangement according to claim 1, characterized in thatthe chain wheels (R11, R12) are arranged directly next to one another on the shaft and are preferably made in one piece.

3. Chain drive arrangement according to claim 1, characterized in that the sprockets (R61, R62) are spaced apart from each other on the shaft.

4. Chain drive arrangement according to one of the preceding claims, characterized in that the chain drive has two sprockets that are mirror-symmetrical to each other.

5. Chain drive arrangement according to one of the preceding claims, characterized by a housing (E1) which surrounds the sprockets and limits the movement space of the chain links on the sprockets in the radial direction.

6. Chain drive arrangement according to claim 5, wherein the housing has two grooves (F1, F2) next to one another on the inside, in which stationary links of the link chain strands running on the sprockets are guided.

7. Lifting device with a chain drive arrangement according to one of the preceding claims and a motor which is connected directly or by gear to the chain drive shaft, wherein the motor is electrically or pneumatically operated.

8. Lifting device according to claim 7, wherein the dimensioning of the motor and, if applicable, an associated gear and / or an associated braking device corresponds to the size of a single link chain strand.

9. Lifting system, comprising a lifting device according to claim 7 and link chain strands (S11, S12) guided via the chain drive of the lifting device and a stop device which has connection points (C11, C12) arranged next to one another for one end link of each link chain strand for fastening ends of said link chain strands (S11, S12) and a connecting part (B1) for a load on a side facing away from the link chain strands, wherein the connection points are arranged at the same height with respect to a load direction.

10. Lifting system according to claim 9, wherein the connecting part comprises a load hook which is preferably mounted on the stop device so as to be rotatable about an axis parallel to the load direction (b).

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