Shutdown buffer for a lifting device, in particular chain hoist, and lifting device herewith

Abstract

A shut-down buffer for a lifting device, in particular a chain hoist, includes two opposing end surfaces and at least two mutually spaced web elements extending between the end surfaces. The shut-down buffer is defined by the end surfaces, between which a through-opening for passage of a load-bearing element of the lifting device extends through the shut-down buffer.

Claims

1. A lifting device comprising: a drive device; a shut-down device for the drive device; and a shut-down buffer for actuating the drive device, the shut-down buffer comprising: first and second opposing end surfaces, between which a through-opening for passage of a load-bearing element of the lifting device extends through the shut-down buffer along a central axis thereof; and at least two mutually spaced web elements extending from and directly coupling the first end surface to the second end surface; wherein the web elements are configured to resiliently buckle in compression when the shut-down buffer is loaded in the direction of its central axis; and wherein the shut-down buffer is disposed on an upper side of a holding part for a load hook of the lifting device and facing a pulling direction of the lifting device.

2. The lifting device as claimed in claim 1, wherein each web element comprises a respective pair of main surfaces, wherein the web elements extend with their respective main surfaces aligned radially in relation to the central axis of the shut-down buffer, the central axis extending within the through-opening and wherein the web elements extend parallel to the central axis and laterally offset therefrom.

3. The lifting device as claimed in claim 2, wherein each respective web element is connected with its main surface to at least one of the end surfaces via an attachment region that forms a flexing point.

4. The shut-down buffer as claimed in claim 3, wherein said flexing points are configured such that in an unloaded state said main surfaces are laterally offset from said attachment regions.

5. The lifting device as claimed in claim 4, wherein each of the end surfaces is formed by a disc-shaped end part that defines a respective opening with a cross-section that corresponds to a geometry of the load-bearing element of the lifting device.

6. The lifting device as claimed in claim 5, wherein the shut-down buffer, including the end parts and the web elements, is formed as one piece.

7. The shut-down buffer as claimed in claim 5, wherein the shut-down buffer is partially open between the end parts and the web elements and radially inwardly to the through-opening.

8. The lifting device as claimed in claim 1, wherein at least the web elements are made from an elastic material.

9. The lifting device of claim 1, wherein the web elements are substantially planar in an unloaded state and assume an arcuate shape when the shut-down buffer is loaded in the direction of its central axis.

10. The lifting device of claim 1, wherein the holding part is a part of a lower block of the lifting device.

11. The lifting device as claimed in claim 1, wherein the shut-down buffer delivers an actuating force to the shut-down device.

12. The lifting device as claimed in claim 11, wherein the shut-down buffer is disposed between the holding part and a housing of the lifting device in such a way that contact between the holding part and the housing is avoided upon actuation of the shut-down device when the load hook is in an upper end position.

13. The shut-down buffer as claimed in claim 1, wherein each respective web element comprises a flexing point proximate each of said first and second opposing end surfaces, and a main surface disposed between said flexing points, and wherein said flexing points couple to said first and second opposing end surfaces at attachment regions and are shaped so that in an unloaded state said main surfaces are laterally offset from said attachment regions.

14. The shut-down buffer as claimed in claim 13, wherein each of said attachment regions is thinner than said main surface and comprises an arcuate shape in the unloaded state, and wherein said main surfaces are substantially planar in the unloaded state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1 and 2 each show a schematic view of a lifting device, formed by way of example as a chain hoist, with a shut-down buffer;

(2) FIGS. 2-5 show schematic views of the shut-down buffer in an unloaded and undeformed state;

(3) FIG. 6 shows a schematic view of the shut-down buffer in a loaded and deformed state; and

(4) FIG. 7 shows a schematic view of portions of a lifting device including two shut-down buffers arranged in parallel.

DESCRIPTION OF PREFERRED EMBODIMENTS

(5) FIG. 1 shows a lifting device formed as a chain hoist 1 for lifting and lowering loads. The chain hoist 1 essentially comprises a housing 1b for receiving a motorised drive unit with a preferably electric drive motor, a transmission and an output shaft on which a chain wheel is mounted in particular for conjoint rotation therewith and can rotate jointly with the output shaft. The chain wheel can be connected to the output shaft, e.g. by means of toothing. Furthermore, the chain hoist 1 comprises a load-bearing means or element in the form of a chain 1a for the indirect pick-up of the load to be moved. The chain wheel and the chain 1a are in form-fitting engagement with each other. By means of the form-fitting arrangement a lifting force resulting from the drive-side torque transmitted by the transmission is introduced into the chain 1a. The chain 1a is connected at one of its ends, which can be raised and lowered and is on the load side as seen from the chain wheel, to a freely suspended load picking-up means in the form of a load hook 2. The other chain end can be fastened to the housing 1b and, together with an unloaded part of the chain 1a, be located in a container-like chain store 1c fastened to the housing 1b, which chain store receives and releases the chain 1a via an opening depending on the direction of rotation of the chain wheel. Furthermore, a guide can be provided in the region of the chain wheel in order to prevent catching or jamming of the chain 1a or of individual chain links between the chain wheel and chain store 1c.

(6) FIG. 1 also shows a holding part 3 on which the load hook 2 is rotatably mounted and fastened. A shut-down buffer 4 is disposed on an upper side of the holding part 3 opposite the load hook 2 and facing the housing 1b, which shut-down buffer lies on the upper side of the holding part 3 and has the chain 1a passed through its through-opening 4d (see FIG. 3) to the holding part 3. By means of the shut-down buffer 4 a shut-down device for the drive motor of the chain hoist 1 is actuated, the at least one end switch 5 of which (see FIG. 2) is disposed on the lower side of the chain hoist 1 or the housing 1b thereof and/or at the exit of the chain store 1c. The shut-down buffer 4 is formed as one piece and produced from an elastic material, preferably a synthetic material such as e.g. polyurethane.

(7) In the illustrated exemplified embodiment of the single-strand chain hoist 1, the chain 1a passed through the through-opening 4d of the shut-down buffer 4 is fastened to the holding part 3 with its free end which can be raised and lowered. Load forces induced by a load are passed from the load hook 2 to the holding part 3 and from there to the chain 1a. Therefore, the shut-down buffer 4 has no load-bearing function. Instead, it serves only to balance out the after-running movement and shut-down of the drive motor. Furthermore, the shut-down buffer 4 is disposed by this arrangement between the holding part 3 and a housing 1b of the chain hoist 1 so that contact between the holding part 3 and the housing 1b is avoided upon actuation of the shut-down device when the load hook 2 is in the upper end position.

(8) Although the illustrated embodiment of FIGS. 1 and 2 depicts the use of the shut-down buffer 4 disposed on an upper side of the holding part 3, above the load hook 2 and on the loaded part of the chain 1a, it will be appreciated that the shut-down buffer 4 may be attached at the unloaded part of the chain 1a, instead of (or in addition to) the shut-down buffer 4 on the loaded part of the chain 1a. This other shut-down buffer would be typically contained in the chain store 1c except to the extent that once a maximum amount of chain 1a has been payed out, with the load hook 2 in the lower end position, the other shut-down buffer is drawn up to the housing 1b where it contacts another end switch located at or near the housing 1b where the chain store 1c is attached. Thus, the shut-down buffer 4 can be used along the “dead” (unloaded) end of the chain 1a, or along the loaded end of the chain 1a above the load hook 2, or two shut-down buffers 4 provided such that one shut-down buffer is at each end region of the chain to trigger separate upper and lower end switches at each desired end of chain travel.

(9) Moreover, it will be appreciated that certain advantages may be achieved by arranging two or more shut-down buffers 4 in series, such as shown in FIG. 7 in which two shut-down buffers 4 are arranged in close proximity to each other, above a holding part 3′. In FIG. 7 the chain 1a is omitted from the space between the upper and lower shut-down buffers 4 and from between the lower shut-down buffer and the holding part 3′. By arranging two or more shut-down buffers 4 in series, additional after-running movement of the chain 1a is possible with lower risk of damage to the shut-down buffers 4 due to over-compression thereof. The use of two or more shut-down buffers 4 in series may also permit for deceleration of a load at the loaded end of the chain over a greater vertical distance, thus reducing peak deceleration of the load once the uppermost shut-down buffer contacts the end switch 5.

(10) In FIGS. 1 and 2, the load hook 2 is raised, but has not yet reached the upper end position and so the shut-down buffer 4 also does not yet lie with its end surface 4a (see FIG. 3), which faces the end switch 5, against said end switch and thus is also still in its unloaded and undeformed state.

(11) FIGS. 3 to 5 also show different views of the shut-down buffer 4 in its unloaded and undeformed state. FIG. 3 shows a perspective view and FIGS. 4 and 5 show side views of the shut-down buffer 4.

(12) FIG. 3 shows in particular that the shut-down buffer 4 is defined by two opposing and, in particular, planar end surfaces 4a, 4b, which are oriented at a right angle to the central axis of the shut-down buffer 4, between which extends the through-opening 4d for passage of a load-bearing means of the lifting device such as e.g. the chain 1a. Furthermore, four mutually spaced web elements 4c extend between the end surfaces 4a, 4b and are disposed in particular around the through-opening 4d uniformly spaced apart from each other. Accordingly, the respective neighbouring web elements 4c or their rectangular main surfaces 4f, which are planar in the illustrated unloaded state, are disposed at a right angle to each other and extend in each case radially and at a right angle to the end surfaces 4a, 4b in a notional plane which contains or encloses the central axis—lying centrally within the through opening 4d—of the shut-down buffer 4. The main surfaces 4f extend in parallel and spaced apart from the central axis, whereby, with their radial extent they define the through-opening 4d in the direction of the central axis.

(13) The end surfaces 4a, 4b of the shut-down buffer 4 are each formed by a planar end part 6, 7 with a circular periphery. The end parts 6, 7 are connected to each other and spaced apart from each other by the web elements 4c. Furthermore, the web elements 4c are connected with their main surfaces 4f to both ends parts 6, 7 via a respective attachment region 4e which in each case forms a desired flexing point. For this purpose, the attachment region 4e engages with the respective end part 6 and 7 in parallel with respect to the main surface 4f or the plane of extension thereof and therefore in a laterally offset manner. The attachments—which are laterally offset accordingly—of each web element 4c are each oriented to the same side of the main surface 4f. By means of the offset attachment of the web elements 4c—this attachment being achieved by means of the attachment regions 4e which extend through a quarter circle—the intentional lateral bulging or buckling of the respective web element 4c opposite to the direction of the offset and therefore to the opposite side of the main surface 4f is facilitated (see FIG. 6).

(14) Also illustrated is a first opening 6a through which a load-bearing means or element, such as the chain 1a in the present case, can enter the through-opening 4d and be passed therethrough in order then to be able to exit the shut-down buffer 4 through a second opening 7a opposite to the first opening 6a. The openings 6a and 7a are defined by the two end parts 6 and 7 of the shut-down buffer 4 or the associated end surfaces 4a and 4b of the shut-down buffer 4 and each have a cross-section which corresponds to the geometry of the load-bearing means or element of the lifting device. In the exemplified embodiment of the lifting device as the chain hoist 1, a cruciform cross-section corresponding to the geometry of the chain 1a is produced. By means of this embodiment of the openings 6a, 7a, the shut-down buffer 4 can also serve for chain guidance and disentanglement.

(15) The view of the shut-down buffer in FIG. 4 differs from that in FIG. 5 by an orientation of the shut-down buffer 4 turned by 45° with respect to the central axis. FIG. 4 shows that the shut-down buffer 4 is open between the illustrated end parts 6, 7 and web elements 4c as far as the through-opening 4d. In FIG. 5 the through-opening 4d is partially concealed by a web element 4c, the main surface 4f of which extends radially away from the central axis and extends perpendicularly to the plane of the drawing. In both FIG. 4 and also FIG. 5 the attachment regions 4e can be seen extending as a quarter of a circle, by which extension the lateral offset of the attachment of the web elements 4c to the end parts 6, 7 is achieved. In the illustrated orientation—which is vertical in terms of its central axis—of the shut-down buffer 4 and of the main surfaces 4f of its web elements 4c, the lateral offset corresponds in each case to a horizontal offset.

(16) FIG. 6 shows the shut-down buffer 4 schematically in the loaded and deformed state which results from the above-mentioned after-running movement when the load hook 2 reaches an end position and the shut-down device is actuated as a result. The shut-down buffer 4 is compressed in the axial direction, i.e. along the central axis of the shut-down buffer 4 by corresponding spring travel with respect to the undeformed state. The end parts 6 and 7 and associated end surfaces 4a, 4b have thereby moved towards each other by the effected spring travel. The effected spring travel results from the fact that the axial loading causes the web elements 4c to bulge in each case opposite to the direction of the lateral offset.

(17) The difference in height thereby produced in the axial direction between the undeformed and the deformed state corresponds to the effected after-running travel of the holding part 3 and of the load hook 2 which these carry out after actuation of the shut-down device by contact of the shut-down buffer 4 against an associated end switch and thereby effected shut-down of the drive motor, until they finally come to a standstill. The end switch can be e.g. the end switch 5 illustrated in FIG. 2 on the underside of the housing 1b.

(18) Changes and modifications in the specifically described embodiments may be carried out without departing from the principles of the present invention, which is intended to be limited only by the scope of the appended claims, as interpreted according to the principles of patent law including the doctrine of equivalents.