| JP55046109 | GAS ANALYZER IN OIL FOR OIL FILLED ELECTRIC UNIT |
| JP03173410 | LC COMPOSITE PART |
| JP06176967 | LAMINATED LC FILTER PARTS |
Claims
1. Lifting hook assembly for the movement and positioning of hollow electric components, especially toroid transformers having a hollow central core, comprising a lifting element provided with a hook arranged along or near to the axis of the center of gravity of said component, and said lifting assembly being firmly fixed to said component, characterized by a lifting element extending substantially in vertical direction, and said hook arranged at the upper end of said lifting element and defining a downwardly facing hook opening; at least one positioning sleeve having a substantially vertical axis and arranged at the lower section of said lifting element and fixed thereto, said positioning sleeve having a hollow central core, and said lifting element and said positioning sleeve extending through said hollow central core of said component and being connected to said hollow central part.
2. The lifting hook assembly as claimed in claim 1, wherein said lifting element comprises a pair of parallel arms bent from a plate in U form connected with each other by a cross member at the bottom, with said described hooks being provided on the upper ends of both of said arms, said cross member defining a pair of bores each receiving and abutting the lower end section of a respective positioning sleeve.
3. The lifting hook assembly as claimed in claim 2, further comprising a lower plate arranged below said cross member and fixed thereto, respective bores are provided in said lower plate just below said bores of said cross member, and said lower end sections of said positioning sleeves being inserted into said bores.
4. The lifting hook assembly as claimed in claim 3, wherein said lower plate has a size and shape which closes the opening of said hollow central core from below to form a cavity in said hollow central core, and said cavity being filled by a solidified molded resin insert, said resin filling said cavity to a predetermined height leaving open said hook.
5. The lifting hook assembly as claimed in claim 4, further comprising a separate counter piece comprising a pair of hooks with upwardly facing hook openings, that can be brought into engagement with said hooks, and has a hook height being smaller than the free space between the upper end of said resin and said hook.
6. The lifting hook assembly as claimed in claim 1, wherein said component is a toroid transformer, and said hollow central part is filled with a resin mold securely connecting said assembly with said transformer. |
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Lifting hook assembly for hollow electric components, especially toroid transformers
Field of the invention
The invention relates to a lifting hook assembly for the movement and positioning of hollow electric components, especially toroid transformers having a hollow central core, comprising a lifting element provided with a hook arranged along or near to the axis of gravity of the transformer, and to which the lifting assembly is firmly fixed.
Background of the invention
The maximum weight of components and machine parts that can be moved by single human effort generally is prescribed by governmental standards or local safety regulations. Parts having greater weight than permitted by these standards and regulations can be installed, assembled, disassembled or removed exclusively by use of lifting devices. These lifting devices can be connected to the parts by means of specially designed eyes, lugs or hooks. For lifting hollow parts, several lugs or hooks must be fixed to the parts, since along the line of the part's center of gravity there is no appropriate place for the fixing of such elements. When the lifting points are placed outside the line of the center of gravity, the part may assume a tilted or unstable position during the lifting operation. Such unstable lifting may cause swaying and result in difficulty correctly positioning of the part. For lifting components that do not have any load-bearing outer surface, specially designed lifting devices are required that must meet a number of requirements, including: providing the required degree of safety, not damage neighboring sensitive components, being capable of quick and accurate placement, and, following the placement of the component, being capable of easy disengagement and removal.
US patent 4,649,640 describes how an electrical transformer with a sensitive surface can be lifted. The transformer is designed to be placed in a standing position, and lugs are fixed at the upper part of its iron core by means of bands or bars, with molded resin surrounding the cross bars holding the lugs, thereby increasing the load- carrying ability lifting device.
This known lifting system cannot be used if the entire iron core is surrounded by copper windings, as the surface of the winding is sensitive to mechanical impacts and is therefore inappropriate for affixing holding the lugs. In the case of toroid transformers, where the entire outside surface consists of the winding, a further difficulty arises from the fact that along the line of the toroid' s center of gravity there is a hollow interior without any stable point to which lugs can be affixed. Similarly, this difficulty appears with all components or parts that have either a cylindrical form or a hollow interior.
Another difficulty associated with the use of lugs in this type of application lies in fact that it does not provide a solution for fixing and positioning the component or part in the equipment into which the components must be inserted. Therefore, the lifting, fixing and positioning tasks are not linked. Lifting of the component is required when it must be installed in electrical equipment or removed therefrom. If the component is large or heavy and cannot be held by hand, or if in the equipment there is no free space for the holding the component by hand, owing to the presence of other components, then both the insertion and removal of the component is difficult and this operation may jeopardize the neighboring parts or other components.
Object of the invention
The object of the invention is to provide a lifting hook assembly which uses a single lifting element placed in, or in close proximity to, the line of the center of gravity of the part to be lifted, thereby enabling the safe lifting and positioning of large and heavy component parts having a hollow design.
Summary of the invention
For attaining this objective, a lifting hook assembly has been provided for the movement and positioning of hollow electric components, especially toroid transformers that have a hollow central core, wherein the assembly comprises a lifting element provided with a hook arranged along or near the line of the center of gravity of the transformer, and the lifting assembly is firmly fixed thereto. According to the invention, the assembly comprises: a lifting element extending substantially in a vertical direction, the hook is arranged at the upper end of the lifting element and
defines a downwardly opening hook; additionally, there is at least one positioning sleeve having a substantially vertical axis arranged within the lower area of the lifting element and connected thereto, such that the positioning sleeve protrudes through the central hollow opening, sufficiently to connect them to the hollow central core of the component.
In the present application the term: "hook" is understood in a general sense, it is an element which can be brought into temporary engagement with an other lifting element. The term "hook" covers therefore a lug, eye or bore that can be engaged with a lifting element of any lifting device, or it can be a shaped profile that can be used for lifting the assembly in engagement with a fitting counterpart.
A preferable embodiment the lifting element comprises a pair of parallel arms bent from a plate in U form, connected with each other by a cross member at the bottom, the hooks are provided on the respective upper ends of the arms, and the cross member defines a pair of bores each receiving and abutting the lower end section of an associated positioning sleeve.
In the aforementioned embodiment it is preferable that the hook assembly comprise a lower plate arranged below the cross member and attached thereto, and respective bores are provided in the lower plate just below the bores the cross member, with the lower end sections of the positioning sleeves inserted in the bores.
The fixing of the assembly can be easily realized if the lower plate has a size and shape which closes the opening of the hollow central part of the component from below to form a cavity in this hollow central part, such that the cavity can be filled by a solidified resin supplied in a previously molded state, such that the resin fills the cavity to a predetermined height that leaves exposed the upper ends of the arms containing the hooks.
The use of the lifting assembly requires employing a separate counter piece that has a pair of hooks with upwardly facing hook openings, which can be engaged with the hooks of the lifting assembly, and the counter piece has a hook height which is smaller than the free space between the upper end of the resin and the hook.
In the most frequently used applications, the component is a toroid transformer, with its hollow central part filled with a molded resin connected securely to the the transformer assembly.
Short description of the drawings
The invention will now be described in connection with preferable embodiments thereof, wherein reference will be made to the accompanying drawings. In the drawing:
Fig. 1 shows the lifting hook assembly in the component partly in section;
Fig. 2 shows separately the lifting hook assembly;
Fig. 3 shows the counter piece of the hooks;
Fig. 4 shows the elevation view of a positioning sleeve; Fig. 5 is the elevation sectional view of the positioning sleeve;
Fig 6 is the enlarged sectional view of one end of the positioning sleeve;
Fig. 7 is the enlarged sectional view of the other end of the positioning sleeve;
Fig. 8 shows the exploded view of the parts of the lifting assembly; and
Fig. 9 shows the perspective view of the lifting hook assembly fixed in a toroid transformer
Detailed description of the preferred embodiments
Fig. 1 shows the design of the lifting hook assembly with the associated const- ructional elements. The assembly comprises lifting hook 11 and positioning sleeves 13 required both for the fixing and accurate placement of the lifting hook 11, and they are all arranged and fixed in the hollow interior of a large and heavy component 12 preferably a toroid transformer, wherein the task includes positioning, placement and removal of the component 12 in a piece of equipment (not shown). The permanent connection between the assembly and the component 12 is solved preferably by using a mold 15 e.g. a plastic resin. A lower plate 14 is used to prevent outflow of the mold 15. The insert plate 14 belongs to the hook assembly and is placed from below under the toroid transformer.
Fig. 2 shows the different parts of the lifting hook assembly, while Fig. 3 shows a counter-piece that can be brought into engagement with the hook and used as a lifting element. It is noted that the reference numerals of the parts and elements used in the respective figures follow the number of the figure on which they are shown, therefore identical elements may have reference numerals differing from each other only in their
first digit. The parts of the lifting hook assembly are shown in Fig. 2 in a position just preceding the application of the mold. The lower plate 24 has bores that receive the two positioning sleeves 23, which are also led through the lower bores of the lifting hook 21, whereby during the application of the mold and later during use the sleeves 23 5 position and hold the lifting hook 21. The upper ends of the positioning sleeves 23 are lower than the upper hook part 25 of the lifting hook 21, and this height difference allows the hooked upper part 25 to extend out of the solidified mold. For the insertion of the counter piece 35 shown in Fig. 3 the shoulder 36 of the counter piece 35 should have sufficient space above the upper plane of the mold and of the positioning sleeves
10 23 to be moved into engagement with the hook 25 from below. The counter piece 35 has a bore 37 for the insertion of a lifting means (not shown) by which, following the engagement of the hook 25 with the counter piece 35, the component can be inserted or removed quickly. After the shoulder 36 has engaged the hook 25, it can be disengaged only by a downward displacement (which may never occur when the counter piece
15 holds the lifting hook), therefore the insertion and removal of the component can be made in a secure way without the danger of any accidental disengagement.
Fig. 4 shows the elevation view of the positioning sleeve, Fig. 5 shows its sectional view along the section plane A-A, while Figs. 6 and 7 show respective enlarged details B and E of the ends of the positioning sleeves. For providing a correct
20 engagement with the mold the outer surface of the positioning sleeves 41 define grooves 42, whereby a form-fitting engagement is provided between the positioning sleeves and the mold in a simple and inexpensive way. Such a secure connection is required, because -as can be observed also in Fig. 1 - the lifting hook 21 transfers the lifting force that counter-acts the load constituted by the weight of the component 12
25 through the positioning sleeves 13 and its own lower end part to the mold, and the mold transmits this force to the inner wall of the component, preferably also in a form-fitting manner. The sectional view of Fig. 5 shows the hollow design of the positioning sleeve. Fig. 6 shows that the upper end of the positioning sleeve defines a hollow cylindrical cavity 51 with an axis falling in the extension of the axis of a hollow central bore 52
30 made in the sleeve. The cavity 51 is made to receive the head of a fixing bolt (not shown), while the bore 52 positions and receives the bolt so that the bolt can be easily connected following the insertion of the component into its place. The other end of the sleeve 41 shown in the enlarged view of Fig. 7 also comprises a deep cavity 53 and a
mouth opening 54 with axes falling in the extension of the axis of the bore 52, and they are used to position the sleeve 41 to a female member with a threaded bore (not shown) fixed in the support plate of the chassis. The common axis of the bore 52, the cavities 51, 53 and the opening 54 enable the easy introduction of the threaded fixing bolt in the positioning sleeve and the engagement thereof with the female member.
Fig. 8 shows the exploded view of the lifting hook assembly. The positioning sleeves 82 and the lower plate 81 sandwich the lower connecting part 85 of the hook element 83. The shoulders of the lower ends of both positioning sleeves 82 are supported by the lower plate 81, and the lower cylindrical ends below the shoulders (that define the mouth opening 54 of Fig. 7) are fitted in the respective bores made in the lower plate 81. For securely connecting the hook element 83 and the lower plate 81, a threaded fixing bolt 84 is provided that can be screwed in a threaded bore made in the lower plate 81. Such a fixing is provided before the molding step is performed, and this is very significant, because the lower plate 81 prevents the liquid mold from escaping from the closed space provided between the hook assembly and the cavity of the component.
Fig. 9 shows the perspective view of the lifting hook assembly when being fixed by a mold in the hollow interior of a toroid transformer 91. It is characteristic of the toroid transformer 91 to have an inner opening with a cross section that gradually decreases from the bottom in upward direction till reaching the central plane, from where the cross section starts to increase. The lifting hook 92 is molded in this inner opening in such a way that the inner space is closed from below by the lower plate (24 in Fig. 2) that abuts the lower surface of the toroid transformer. The mold fills therefore both regions of the inner opening below and above the central plane. By such a design the solidified mold can transfer the axial forces acting in any direction on the lifting hook 92 and on the positioning sleeves to the large toroid-shaped inner surface of the transformer. Owing to the form-fitting connection there is no need for using additional connecting or fixing elements between the mold and the transformer, whereby the transformer can be inserted and fixed in an easy and inexpensive way. An advantage of such a fixing lies in that the forces act in the central axis of the transformer, wherein the forces are mostly constituted by the weight of the transformer, and this ensures additional safety during insertion and removal, as unwanted torques will not occur. If the toroid transformer is used in the interior of a piece of equipment, and for the sake of
maximum space utilization there is no free space around the transformer, the present invention can provide a safe and secure insertion and removal of the toroid transformer without endangering or damaging the components positioned close to the transformer. When the toroid transformer has to be inserted in the equipment, it is supposed that respective threaded bolts or threaded nuts extend out from the base plate of the equipment in locations that correspond to the required placement of the positioning sleeves, and when the toroid transformer is suspended by the hook assembly and placed above its intended position, the hook assembly is lowered and the aforementioned bolts or nuts that extend out from the base plate are guided into their positions by the wider hollow end sections of the positioning sleeves and the assembly can be fully lowered. In this position the bolts or nuts can be fixed to the base plate of the equipment by respective threaded counter parts inserted through the upper opening of the positioning sleeves. The disassembly and removal takes place in reverse order, first the screws are disengaged, then the lifting counterpart must be brought into engagement with the hook, then the assembly can be lifted easily without endangering the neighboring components.
Although the present invention can be used primarily and most preferably for the insertion, fixing and removal of toroid transformers, it can be used in a similar way for the placement and removal of any similar large and heavy component, such as other types of transformers or smaller hollow equipment parts, therefore the invention cannot be limited to use in toroid transformers only.