Noise-reducing and retrofittable encasing device for a hoist

Abstract

Noise-reducing and retrofittable enclosing device for a hoist, in particular a chain hoist, with a housing enclosing a drive, gear and brake unit as well as a sprocket for a load chain, characterized in that the device comprises a removable shell that substantially completely encloses the drive, gear and brake unit as well as the sprocket, wherein the shell has a multi-layered or structurally complex, sound-insulating and sound-absorbing structure, and wherein the shell has at least a first closable opening for the load chain and a second opening for a suspension device, and wherein the first opening is provided with a flexible sealing device designed to dynamically conform to the contour of the passing load chain in order to minimize sound emission while allowing the passage of the load chain.

Description

1. Title of the invention

[0001] Noise-reducing and retrofittable encasing device for a hoist 2. Description 2.1. Technical area

[0002] The invention relates to the technical field of noise reduction technology for lifting equipment. It relates in particular to devices for the acoustic encapsulation of manually or power-operated chain hoists, pulleys, and similar lifting devices. Furthermore, the invention relates to accessories for such lifting equipment that enable or facilitate their use in noise-sensitive environments. 2.2. State of the art

[0003] Lifting equipment such as spur gear chain hoists or pulley blocks are widely used in industrial, commercial, and rescue applications. A significant disadvantage of these devices is their high noise emissions during operation. The rolling of the metallic load chain over the sprocket, the friction in the chain guides, and the mechanical noises from the gearbox and especially the load brake (e.g., the clicking of a pawl) generate sound pressure levels typically ranging from 85 dB(A) to 90 dB(A). This noise level is not only potentially harmful to the operator's health but also precludes the use of such lifting equipment in many noise-sensitive environments. These include hospitals, nursing homes, veterinary clinics, as well as nighttime rescue operations and work in residential areas.

[0004] The prior art discloses various approaches to noise reduction in chain hoists, which, however, differ fundamentally from the present invention. These approaches can be divided into four main categories: Category 1: Internal mechanical noise reduction

[0005] Several solutions aim to reduce noise generation through internal design modifications of the hoist. For example, German patent application DE 41 11 520 A1 describes a chain hoist with two load chains and offset chain sprockets to reduce vibrations induced by mechanical smoothness. German patent application DE 103 14 724 A1 proposes an electronically controlled damper to compensate for the polygon effect at the sprocket, thereby minimizing chain vibrations. Furthermore, German patent application DE 10 2014 101 654 A1 discloses the use of a slip clutch in the drive train to absorb torsional vibrations. These measures focus on reducing vibrations and mechanical irregularities at the source. While they can achieve some noise reduction, they do not address all noise emissions, particularly the loud rattling of the chain in the guides or the harsh engagement of the brake.Furthermore, these solutions are integral components of the hoist design and cannot be retrofitted to the millions of standard chain hoists already in use. They do not offer a solution to the problem of making existing equipment quieter. Category 2: Alternative lifting technologies

[0006] Another approach is to replace the noisy lifting element, the chain. German patent DE 10 2010 047 704 A1 proposes using a toothed belt instead of a round steel chain. While this results in quieter operation, it represents a fundamentally different technology. It is not an improvement on a chain hoist, but rather its replacement with a different lifting principle. Therefore, this solution is not an alternative for users who rely on the robustness and specific advantages of a chain hoist, and it does not solve the problem of dampening the noise of an existing chain hoist. Category 3: General acoustic enclosures and barriers

[0007] The principle of encapsulating a noise source with a soundproof enclosure is well-known. Mobile noise barriers, sound-absorbing ceilings and curtains, as well as complete enclosures for stationary machinery, exist. Enclosures are also known for other equipment such as winches, as described, for example, in US 11,767,201 B2, where a winch enclosure surrounds a winch. The crucial technical challenge with a chain hoist, which is not addressed by these general solutions, is the need to pass moving parts—namely the load chain and the hand chain—through the enclosure while it is in operation. A chain hoist has a continuous chain path with an incoming and an outgoing run of the load chain, the position of which can change relative to the enclosure. A simple opening in an enclosure would act as an acoustic short circuit and negate the soundproofing effect.The existing enclosures do not offer a solution to the problem of effectively sealing such a dynamic feedthrough from an acoustic perspective without impairing the function of the hoist. The specific geometry and operation of a chain hoist thus pose particular requirements that cannot be met by generic enclosures. Category 4: Additive manufacturing for acoustic and structural applications

[0008] Additive manufacturing (AM), commonly known as 3D printing, has established itself as a powerful tool for producing complex geometries. In the field of acoustics, AM is known to be used to create so-called acoustic metamaterials. These are artificially structured materials whose acoustic properties depend not primarily on their chemical composition, but on their precisely designed internal structure. Such structures, for example in the form of labyrinths, cellular grids, or resonators, can manipulate sound waves in ways that are not possible with homogeneous materials, such as selectively absorbing or blocking sound in specific frequency ranges. Furthermore, the use of fiber-reinforced plastics in 3D printing is known to produce components with high strength and low weight, whose mechanical properties are comparable to those of aluminum.Furthermore, computer-aided topology optimization methods are used to optimize the material distribution within a component so that it achieves maximum performance for a specific task, such as sound insulation or heat dissipation, with minimal material usage. Finally, AM enables the production of components with integrated, conformal cooling channels that follow complex internal contours to optimize heat dissipation.

[0009] Although these technologies and methods are known individually in the prior art, no prior art discloses a solution that combines and applies these principles to provide a retrofittable, fully enclosing, and acoustically effective sheathing device for a chain hoist. In particular, the synthetic integration of lightweight construction through fiber-reinforced materials, targeted sound absorption through metamaterial structures, optimized passive cooling through conformal channels, and the solution to the sealing problem of the chain feedthroughs in a single, additively manufactured component represents a novel and inventive solution. A person skilled in the art of hoist construction would not readily combine insights from academic research on metamaterials, lightweight construction in the aerospace industry, and tool cooling to solve the specific noise problem of a standard chain hoist.

[0010] In summary, it can be stated that the state of the art does not reveal a solution that provides a retrofittable, acoustically effective enclosing device for a chain hoist that essentially completely encloses the hoist, solves the specific problem of sealing the chain feedthroughs, and simultaneously utilizes advanced manufacturing methods for the simultaneous optimization of acoustics, weight, and thermal management. 2.3. Object of the invention

[0011] Based on the disadvantages of the prior art, the present invention aims to create a device for noise reduction for lifting equipment such as chain hoists, which simultaneously fulfills the following, partly conflicting requirements: • It is designed to drastically reduce the operating noise level of the hoist, enabling its use in noise-sensitive environments. • It should be designed as an easy-to-use, robust and cost-effective accessory that can be retrofitted to a wide variety of existing lifting equipment without any structural changes to the lifting equipment itself (retrofit capability). • The full functionality, operability and, in particular, the safety-relevant load-bearing capacity of the lifting equipment must be maintained without restriction. • It must effectively solve the technical problem of sound emission at the necessary feedthrough openings for the load and hand chains. • It should achieve maximum sound reduction across a wide frequency spectrum with minimal weight and construction volume. • It should reliably dissipate the heat generated during operation by the encapsulated hoisting device in order to ensure safe continuous operation, whereby the necessary openings must not compromise the acoustic encapsulation. • It should enable cost-efficient, on-demand production of custom-fit variants for a wide variety of lifting equipment models. 2.4. Description of the invention and advantageous embodiments

[0012] To solve this problem, a noise-reducing and retrofittable encasing device for a lifting device is proposed according to the features of the claims. Advantageous embodiments of the invention are the subject of the dependent claims. 2.4.1. General description of the invention

[0013] The device according to the invention is designed as a removable casing that essentially completely encloses and acoustically encapsulates the main noise sources of a hoist – namely, the drive, transmission, and brake units, as well as the sprocket. In the assembled state, the upper suspension element of the chain hoist (e.g., the lifting hook) protrudes through an upper opening of the device, while the load chain with the load hook enters and exits through a lower opening. The hand chain for operating the hoist is also guided through a separate, sealed opening.

[0014] A key feature of the invention is the multi-layered or structurally complex design of the casing, which is based on the fundamental principles of acoustics: sound insulation (blocking sound through mass and stiffness) and sound absorption (conversion of sound energy into heat through porous or resonant structures). This design ensures a highly effective reduction of both airborne noise penetrating to the outside and structure-borne noise generated by vibrations of the hoist housing. Another essential feature is the specific design of the necessary openings for the load chain. In particular, the opening for the load chain is equipped with a special, flexible sealing device. This sealing device is designed to fit snugly against the chain links to minimize the open cross-section and thus sound emission, while simultaneously ensuring the smooth passage of the chain.

[0015] The invention is described in detail below in three preferred embodiments, which represent a technological advance from a flexible basic solution to a highly integrated, additively manufactured functional structure. 2.4.2. Design 1: Flexible fabric cover

[0016] In a first embodiment, the sheathing device is designed as a flexible cover that encloses the lifting device, similar to a precisely fitting coat or bag. This design is characterized by its low weight, flexibility, and ease of storage. It fits the lifting device snugly and is secured by circumferential tension straps with clamp buckles and by large hook-and-loop fasteners, which allow for easy opening and closing of the cover. • Material structure: The structure of the fabric covering is multi-layered in order to achieve optimal acoustic effect according to the mass-spring-mass principle or the principle of combined insulation and absorption. • Outer layer: The outer skin consists of a mechanically robust, weather- and UV-resistant, and flame-retardant technical fabric, such as PVC-coated polyester or ballistic nylon. This material provides protection against external influences and serves as the first sound-reflecting layer. • Middle layer (mass layer): A layer of a heavy, flexible material, preferably a mass-loaded vinyl (MLV) mat, is embedded in or bonded to the outer skin. This layer has a high density at a low thickness (e.g., 5 kg / m²). 2 ) and is crucial for blocking airborne noise (high sound insulation, STC value >25). • Inner layer (absorption layer): The inner layer facing the hoist consists of a thick, open-cell acoustic foam, e.g., polyether or melamine resin foam. This layer absorbs the sound generated and reflected inside the shell, prevents resonances, and converts the sound energy into heat. Through direct contact with the hoist housing, it also dampens structure-borne vibrations. To protect against contamination from oil or dust, the foam can be covered with a thin, acoustically transparent film. • Fastening system: The flexible cover is attached to the hoist using wide, industrial-grade hook and loop fasteners and / or adjustable tension straps with buckles. These fasteners are crucial for functionality: They allow for quick assembly and disassembly and ensure that the cover fits snugly and vibration-free against the hoist. Industrial-grade hook and loop fasteners offer high shear strength and are insensitive to vibrations, unlike simple zippers, which can themselves become a source of noise. 2.4.3. Design 2: Dimensionally stable shell housing

[0017] In an alternative, particularly high-performance embodiment, the casing consists of a dimensionally stable, two-part shell housing that is placed around the hoist and sealed according to the clamshell principle. This variant offers very high sound insulation and additional mechanical protection. The housing consists of two essentially symmetrical half-shells which, when joined, completely enclose the hoist. • Material composition: • Outer shells: The two half-shells are made of a hard, impact-resistant material, such as glass fiber reinforced plastic (GFRP), deep-drawn ABS plastic, or aluminum. This hard outer shell reflects the incident sound very effectively. • Interior lining: The inner surfaces of the shells are lined with a two-stage insulation system. A thin layer of viscoelastic damping material is applied directly to the hard outer shell. This forms a so-called "constrained layer damping" system with the hard outer shell, which extremely effectively converts structure-borne noise and resonance vibrations of the shell itself into heat. A thick layer of open-cell acoustic foam is then applied over this to absorb airborne noise inside. • Locking system: The two halves are connected using vibration-resistant quick-release fasteners that generate a high and defined clamping force or preload. Quarter-turn quick-release fasteners (e.g., from the brands Camloc or Southco) or adjustable toggle clamps are particularly suitable for this purpose. 27These fasteners connect the flanges of the two shell halves and, through their mechanics, create a defined preload that ensures a tight and gap-free connection. They guarantee that the two shell halves will not separate or rattle against each other under the vibrations of the hoist operation, thus ensuring the acoustic integrity of the capsule. 2.4.4. Embodiment 3: Additively manufactured, topology-optimized shell housing with integrated functional structures

[0018] This most advanced embodiment utilizes the design freedom of additive manufacturing (AM) to create a monolithic, multifunctional casing produced in a single manufacturing process, integrating acoustic, thermal, and structural functions that would be impossible or extremely difficult to achieve using conventional methods. • Manufacturing process and material: The housing is manufactured as a single piece or as a two-shell construction using additive manufacturing processes such as Fused Filament Fabrication (FFF) or Selective Laser Sintering (SLS). High-strength, fiber-reinforced polymers are primarily used as materials, such as polyamide with short or continuous carbon fibers (PA-CF) or glass fibers (PA-GF). These materials offer stiffness and strength comparable to aluminum, but at a significantly lower weight. This minimizes the additional load on the lifting equipment and facilitates handling. The use of such materials is ideal for housings and load-bearing covers. • Integrated acoustic metamaterial structure: Instead of a simple foam lining, the cavity between the outer wall of the housing and the hoist is filled with a complex, computer-generated grid structure. This is printed directly onto the outer wall. This structure is designed as an acoustic metamaterial. Through the precise design of the cell geometry (e.g., as a gyroid, Kelvin cell, or labyrinth structure), the rib and wall thicknesses, and the porosity, sound absorption can be specifically optimized for the dominant frequency ranges of the hoist (e.g., the high-frequency clicking of the brake, the mid-frequency gearbox noise). This principle of sound wave scattering and dissipation in a complex, resonant structure enables higher absorption performance with less material compared to solid foam. • Integrated, topology-optimized heat dissipation: The air inlet and outlet openings required for cooling the hoist are not simple holes, but rather an integral part of the housing structure. Topology optimization algorithms generate winding, labyrinthine channels within the housing wall or the metamaterial structure. These conformal cooling channels follow the contours of the heat sources (motor, gearbox) and are designed to provide maximum surface area for heat transfer to the flowing air. Simultaneously, the sound path through these channels is so long and convoluted that the sound waves are effectively dampened by multiple reflections and absorption at the encapsulated, porous channel walls. This resolves the conflict between necessary cooling and maximum acoustic encapsulation. • Multi-material printing for integrated seals and damping: In a particularly advantageous embodiment, the housing is manufactured using a multi-material 3D printing process. This allows the rigid, fiber-reinforced structure of the housing (e.g., made of PA-CF) and the flexible, abrasion-resistant sealing lips for the chain guide (e.g., made of a thermoplastic elastomer such as TPU) to be produced as a seamlessly joined component in a single printing process. This eliminates joints that could represent potential sound bridges. Furthermore, targeted viscoelastic, damping material zones (e.g., using materials such as Damping ToughRubber™) can be integrated directly into the structure to absorb vibrations from the hoist directly at the contact surface. • Adaptability and on-demand manufacturing: A key advantage of this approach is the ability to produce a perfectly fitting enclosure for each specific hoist model without tooling costs. By simply modifying the 3D CAD model, the geometry can be precisely adapted to the contours of the respective hoist, minimizing voids and maximizing acoustic efficiency. This enables economical on-demand manufacturing even for small production runs or niche models. 2.4.5. Detailed features and technical specifications • A. Sealing of the feedthrough openings: Solving the core problem of acoustic leakage at the chain feedthroughs is a crucial feature of the invention. The sealing device at the opening for the load chain is preferably designed as an arrangement of overlapping, flexible, and abrasion-resistant sealing lips made of elastomers (e.g., polyurethane or silicone). This sealing device consists of several layers of flexible sealing lips that, due to their elasticity and shape, conform to the contour of the passing chain links and dynamically close the gap. Alternatively or in combination, a brush seal with dense, flexible bristles can be used, which minimizes the free cross-section but does not impede the movement of the chain. This design constitutes an acoustic "siphon" that prevents the direct escape of sound waves. • B. Heat dissipation system: An encapsulated lifting device, in particular an electrically operated one, generates heat during operation, which must be dissipated to prevent overheating. The device according to the invention therefore integrates a heat dissipation system. • Passive heat dissipation: In the preferred embodiment, heat dissipation occurs passively. For this purpose, ventilation openings are provided in the casing or housing, designed as acoustic labyrinths or deflection silencers. In this design, the airflow is guided through a coiled channel lined with sound-absorbing material. While the air can circulate freely (natural convection), the sound waves propagating in a straight line are reflected and absorbed at the deflections, so that hardly any sound escapes to the outside. In the rigid embodiment (2 and 3), external cooling fins can also be molded on to increase the heat-dissipating surface area and improve convection. • Active heat dissipation (optional configuration): For applications with high thermal loads, the system can be supplemented by installing very quiet, slow-running fans (so-called "silent fans") in the soundproofed ventilation openings. These fans force airflow and significantly increase cooling performance without themselves generating any significant noise. 2.4.6. Comparative overview of the embodiments

[0019] The following table summarizes the essential characteristics of the described embodiments and illustrates the technological progress. feature Version 1: Flexible cover Version 2: Dimensionally stable shell Version 3: Additively manufactured functional structure Manufacturing process Clothing manufacturing, sewing GRP lamination, thermoforming Additive manufacturing (FFF, SLS) Material (Exterior / Structure) PVC fabric, MLV GRP, aluminum, ABS Fiber-reinforced polymer (PA-CF / GF) Acoustic principle Mass-spring-mass Mass,ConstrainedLayer Damping Mass, metamaterial resonance / scattering Internal insulation open-cell foam Viscoelastic layer + foam Integrated cellular metamaterial structure Heat dissipation Limited, passive openings Passive labyrinth openings, cooling fins Integrated, topology-optimized cooling channels Weight Small amount High Very low (relative to the strength) Adaptability Universal, but not a perfect fit Model-specific (high tooling costs) Model-specific (no tooling costs) Estimated insulation (DpA) 15-25 dB 25-40 dB > 35 dB (frequency-selectively optimized) Manufacturing complexity Small amount Medium High (digital), low (manual) 2.5. Areas of application

[0020] The sheathing device according to the invention opens up new fields of application for chain hoists where their use was previously not possible or desirable due to noise pollution. These include in particular: • Rescue services and disaster relief: Particularly in large animal rescues using mobile tripod systems, the quiet operation of the lifting device protects the injured or frightened animal and prevents further stress. During nighttime operations by the fire department or THW (Federal Agency for Technical Relief), noise pollution for residents is minimized. • Medicine and veterinary medicine: In hospitals or veterinary clinics, heavy medical equipment or sedated large animals can be lifted without disturbing the clinic's operations or the rest of the patients or animals. • Commercial indoor areas: Maintenance or installation work in office buildings, museums, schools or theatres can be carried out during normal operating or opening hours, as the noise is reduced to a non-critical level. • Event technology: Even with electric chain hoists in stage construction, the operating noise during rehearsals or performances can be minimized, which is particularly advantageous in quiet scenes. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 41 11 520 A1

[0005] DE 103 14 724 A1

[0005] DE 10 2014 101 654 A1

[0005] DE 10 2010 047 704 A1

[0006] US 11,767,201 B2

[0007]

Claims

[1] Noise-reducing and retrofittable enclosing device for a lifting device, in particular a chain hoist, comprising a housing enclosing a drive, gear and brake unit and a sprocket for a load chain, characterized by that the device comprises a removable shell substantially completely enclosing the drive, transmission and brake unit as well as the sprocket, wherein the shell has a multi-layered or structurally complex sound-insulating and sound-absorbing structure, and wherein the shell has at least a first closable passage opening for the load chain and a second passage opening for a suspension means, and wherein the first passage opening is provided with a flexible sealing device designed to dynamically conform to the contour of the passing load chain in order to minimize sound emission while allowing the passage of the load chain. [2] A one- or multi-part housing for a hoist manufactured using an additive manufacturing process to reduce noise emissions, characterized by , that the housing has an outer, load-bearing shell structure and an inner, cellular structure, wherein the shell structure and the cellular structure are integrally designed as a single component or as joined, complementary components, and wherein the cellular structure is configured as an acoustic metamaterial to dissipate sound energy through resonance and / or scattering. [3] Device according to claim 1, characterized by that the casing is designed as a dimensionally stable housing consisting of at least two half-shells, which is detachably connected by means of vibration-resistant quick-release fasteners. [4] Device according to claim 1, characterized bythat the cover is designed as a flexible fabric cover which can be fixed to the lifting device by means of hook and loop fasteners and / or tension straps. [5] Device according to claim 1 or housing according to claim 2, characterized by , that the structure has an outer, heavy and / or stiff sound-reflecting layer and an inner, porous or cellular sound-absorbing structure. [6] Housing according to claim 2, characterized by that it is made from a fiber-reinforced polymer, in particular a carbon fiber or glass fiber reinforced polyamide. [7] Housing according to claim 2 or 6, characterized by that the cellular structure is formed as a gyroid, honeycomb or labyrinthine grid. [8] Device according to any one of the preceding claims, characterized bythat the casing or housing is provided with at least one ventilation opening designed as an acoustic labyrinth or deflection silencer to allow passive heat dissipation while simultaneously attenuating sound. [9] Housing according to claim 2, 6 or 7, characterized by , that within the shell structure or the cellular structure, conformal cooling channels designed by means of topology optimization are integrated, which connect the ventilation openings. [10] Device or housing according to any one of the preceding claims, characterized by that the sealing device is designed as an arrangement of overlapping, elastic sealing lips or as a brush seal. [11] Housing according to one of claims 2, 6, 7 or 9, characterized by that the sealing device is integrally connected to the shell structure by means of a multi-material additive manufacturing process using an elastomeric material. [12] Device according to claim 3, characterized by that the quick-release fasteners are designed as quarter-turn fasteners or toggle clamps, which create a defined preload between the half-shells. [13] Device according to claim 3, characterized by that the inner surfaces of the half-shells are coated with a viscoelastic material to dampen structure-borne sound vibrations.