Shock reducing element

Abstract

Shock reducing element (1) with two end-face receptacles (2), comprising: - meandering folding structures (11, 12, 13, 14) which extend side by side in a longitudinal direction (L) between the end-face images (2), - wherein the folding structures (11, 12, 13, 14) each have several longitudinal lever arms (3, 4) and several transverse lever arms (5), - wherein the folding structures (11, 12, 13, 14) each have several flexible joint areas (6) via which the longitudinal lever arms (3, 4) and the transverse lever arms (5) are connected to each other, - wherein bridge-forming elements (9) are designed between the folding structures (11, 12, 13, 14) and - wherein each bridge-forming element (9) connects two longitudinal lever arms (3, 4) of two adjacent folding structures (11, 12, 13, 14).

Description

[0001] State of the art: DE 10 2019 206 934 A1, DE 10 2020 201 772 A1, EP 2 607 553 A1 WO 2007 / 105 195 A1

[0002] Summary: The invention relates to a device for defined impact energy absorption through elastic, elastic-plastic, and fully plastic deformation based on the unfolding principle for logistics systems and alternative applications under tensile stress. Multicellular folding structures with flexible plastic hinges are incorporated into a band-shaped metal strip, which unfolds upon impact due to tensile stress. Instead of the band-shaped strip, tubular and profile-shaped initial dimensions with a corresponding folding structure can also be used.

[0003] In order to ensure that such a device offers a predetermined and uniform deformation force curve during loading to achieve a desired and high energy absorption, the invention proposes to design the folding structures with the flexible plastic joints accordingly through the geometry of the folding structure so that a targeted elastic, elastic-plastic and fully plastic deformation for impact energy absorption can be achieved.

[0004] The elastic deformation components generate an approximately linear increase in force and the subsequent elastic-plastic and fully plastic deformation produces a force plateau corresponding to the desired buffer characteristic. DescriptionState of the art

[0005] Energy-absorbing systems are known, for example, from the documents DE 10 2019 206 934 A1, DE 10 2020 201 772 A1, EP 2 607 553 A1 and WO 2007 / 105 195 A1.

[0006] WO 2007 / 105 195 A1: Energy Absorbing Element for Wall Openings and Methods of use therefor - Connecting elements of components in the event of an explosion in the construction sector

[0007] EP 2 607 553 A1: Device and method for energy dissipation - Application to rope structures

[0008] DE 10 2019 206 934 A1: Crash box for a motor vehicle - Compressive stress

[0009] DE 10 2020 201 772 A1: Crash box for a motor vehicle - Compressive stress

[0010] To improve performance in logistics systems, operating speed and acceleration are constantly being increased. This significantly increases the load on system components, especially in emergency situations such as emergency braking or buffer surges.

[0011] Logistics facilities must be equipped to safely bring a storage and retrieval machine to a standstill at the end of its travel path with a maximum permissible deceleration, such as a buffer or other equivalent device to absorb the energy from the travel movement. With regard to end-of-movement limitations, conveyor systems such as storage and retrieval machines or smaller conveyor and crane systems must always be designed in such a way that a buffer impact can occur in every conceivable operating situation without causing damage to the machine or other components. In extreme cases, damage to systems and equipment can otherwise occur, resulting in high costs due to repairs and the associated loss of production. It is therefore necessary to provide sufficiently dimensioned and performance-appropriate impact reduction elements at the limits that can absorb the kinetic energy at defined forces.

[0012] The following requirements for the structures of impact reduction elements must be taken into account: • the amount of energy to be absorbed according to the load levels, • the permissible local deformations, • the minimum and maximum force levels and force fluctuations and the • permissible deceleration values.

[0013] In the case of a single, possibly recurring impact, the goal is to reduce displacement, force, or deceleration by converting the impact energy (kinetic energy) of an impacting mass into heat and, in many cases, also into deformation energy and potential energy. Buffers of various design principles are available for this purpose, equipped with springs of various types and characteristics, hydraulic or pneumatic shock absorbers, or frictional sliding pairs. This objective can be achieved by: • elastic deformation, • plastic deformation, • hydraulic flow resistance by throttling liquids or gases, • Friction between solid bodies.

[0014] The design of impact reduction elements, also known as buffers, depends essentially on the desired shape of the characteristic curve. The characteristic curves are presented as force-displacement diagrams or deceleration-displacement diagrams. A prerequisite for optimal design and appropriate adaptation of the characteristic curves to the desired shape is precise knowledge of all the data important for determining the impact energy. To select a suitable buffer system for the specific application, the functional requirements must be known. The most well-known and most frequently used buffers, which predominantly operate under compressive loads, are: • Rubber buffers, • Cellulose buffer, • Elastomer buffer, • Spring buffer, • Hydraulic buffer.

[0015] Alternative applications for specific energy absorbers, known as crash boxes, exist for passenger cars and other applications: • in commercial vehicles, e.g. as underrun protection for trucks, • for the driver and front passenger seat to reduce occupant acceleration in rear-end collisions, • on tanks and mine clearance vehicles, • for structural components in aircraft and helicopters, • in seats in vehicles at risk of explosion, • for railway carriages, • and ships.

[0016] Crash boxes are designed to absorb energy from accidents and also operate under compressive loads. Crash boxes are often made of steel, aluminum alloys, or carbon fiber composites. Additionally, crash boxes can be constructed unfilled or filled, e.g., with aluminum or plastic foams. Crash boxes can generally be differentiated according to the type of energy conversion, the material used, the filling, and the characteristic manufacturing processes. The following mechanisms for energy conversion in thin-walled structures under axial load are known in the literature: • Folding, • free inversion, • forced inversion, • Rejuvenation, • Widening, • Cut.

[0017] The dominant mechanism for crash boxes is folding under compressive stress. However, it is known that the robustness of axially loaded compression tubes is not always guaranteed, as even small changes in impact angle cause the folding to transition from a symmetrical shape to a bi- or triangular fold. These folds are characterized by unstable and oscillating force curves, which exhibit a force peak at the beginning of the folding. Task and disclosure of the invention

[0018] The invention with the features of claim 1 is based on the fact that the shock-reducing element, also referred to as a buffer, with the defined folding structures only performs the desired function under tensile stress – analogous to a tension damper. The following explanations refer to a metallic strip into which the folding structures with the corresponding folding mechanisms are incorporated. Tube-like profiles or other forms of semi-finished products can also be designed analogously as shock-reducing elements. The folding structures can be produced, for example, by laser or water jet cutting or punching. Preferred or advantageous embodiments of the invention emerge from the dependent claims, the following description, and the accompanying figures.

[0019] The geometric design of the folded structures allows for the desired buffer force curve to be set. The desired buffer force curve can be adjusted by adjusting the number of folds, the angles between the lever arms, the dimensions of the lever arms, and the geometric variation of the material width for the lever-arm-like folded structures and the flexible joint areas, which act similarly to plastic hinges. The elastic, elastic-plastic, and fully plastic material behavior of the folded structures under tensile loads are dominant factors in setting the required deformation-force curve of the impact reduction element.

[0020] The elastic deformation components produce an approximately linear increase in force and the subsequent elastic-plastic and fully plastic deformation produces a force plateau corresponding to the desired buffer force characteristic.

[0021] These so-called multicellular folding structures can be designed as closed and / or open to adjust the characteristic curve. Another design parameter is the interconnection of these multicellular folding structures through the number of bridging elements.

[0022] Additional scaling parameters for varying the force level and progression are the elastic-plastic material behavior of the metallic material used and in particular the material thickness of the metal strip.

[0023] In contrast to the hydraulic shock reduction elements used, the invention offers the following advantages: Cost advantages due to significantly lower manufacturing costs, freedom from maintenance, easier assembly and disassembly due to smaller dimensions and weight advantages, independence from the temperature and humidity in the working environment, insensitivity to contamination in the working area, worldwide availability and manufacturability due to classic manufacturing processes, exclusively metallic system without the need for additional damping media.

[0024] From the present disclosure, further application examples are obvious to the expert in which the shock reduction element described according to the invention can be used advantageously.

[0025] The features, advantages, and effects of the invention will become apparent from the following description of an embodiment of the invention. In the following: Fig. 1 shows an embodiment of the shock reduction element in plan view. Fig. Figure 2 shows an average load situation of the shock reduction element in plan view. Fig. 3 shows a large load situation of the shock reduction element in plan view.

[0026] Corresponding or identical parts are provided with the same reference numerals in the figures.

[0027] Fig. Figure 1 shows a schematic top view of the shock reduction element (1). It is attached via a front-end mounting hole (2). The desired profile of the buffer characteristic curve can be adjusted by varying the number of folds, the angles between the lever arms (3), the dimensions of the lever arms (4), and the geometric variation of the material width (5) for the lever-arm-like folding structures and the flexible joint areas (6), which act similarly to plastic hinges. The multicellular folding structures can be designed closed (7) and / or open (8) to adjust the characteristic curve. A further design parameter is the linking of these multicellular folding structures through the number of bridge-forming elements (9).

[0028] Fig. Figure 2 shows a medium load situation of the shock reduction element in plan view and the resulting deformation and thus the principle of the multicellular folding structure.

[0029] Fig. Figure 3 shows a high load situation of the shock reduction element in plan view and the resulting deformation and thus the principle of the multicellular folding structure. List of reference symbols 1 shock reduction element 2 mounting holes 3 Angle between the lever arms 4 Dimensions of the lever arms 5 Material width 6 Flexural joint 7 closed folding structure 8 open folding structure 9 bridging element

Claims

[1] Shock reducing element (1) with two end-face receptacles (2), comprising: - meander-shaped folding structures (11, 12, 13, 14) which extend next to one another in a longitudinal direction (L) between the end-side receptacles (2), - wherein the folding structures (11, 12, 13, 14) each have a plurality of longitudinal lever arms (3, 4) and a plurality of transverse lever arms (5), - wherein the folding structures (11, 12, 13, 14) each have a plurality of flexible joint regions (6) via which the longitudinal lever arms (3, 4) and the transverse lever arms (5) are connected to one another, - wherein bridge-forming elements (9) are formed between the folding structures (11, 12, 13, 14) and - wherein each bridge-forming element (9) connects two longitudinal lever arms (3, 4) of two folding structures (11, 12, 13, 14) extending side by side. [2] Shock reducing element (1) according to claim 1, wherein longitudinal lever arms (3, 4) of a folding structure (11, 12, 13, 14) extend parallel to longitudinal lever arms (3, 4) of another folding structure (11, 12, 13, 14) in an unloaded state (S1) of the shock reducing element (1). [3] Shock reduction element (1) according to one of the preceding claims, wherein the bridge-forming elements (9) extend in a transverse direction (Q) in an unloaded state (S1) of the shock reduction element (1), wherein the transverse direction (Q) extends orthogonally to the longitudinal direction (L). [4] Shock reduction element (1) according to one of the preceding claims, wherein a longitudinal lever arm (3, 4) and a transverse lever arm (5) are formed on a flexible joint region (6). [5] Shock reduction element (1) according to claim 4, wherein a transverse lever arm (5) with two flexible joint regions (6) formed thereon each forms a Z-shape or substantially a Z-shape and wherein directly adjacent to at least one Z-shape a transverse lever arm (5) with two flexible joint regions (6) formed thereon each forms an S-shape or substantially an S-shape. [6] Shock reduction element (1) according to one of the preceding claims, wherein each folding structure (11, 12, 13, 14, 15) in an unloaded state (S1) of the shock reduction element (1) has a first row of longitudinal lever arms (3) and a second row of longitudinal lever arms (4), wherein the longitudinal lever arms (3) of the first row and the longitudinal lever arms (4) of the second row each extend parallel to one another in the unloaded state (S1), wherein the longitudinal lever arms (3) of the first row are spaced from one another in the longitudinal direction (L) by gaps (8), wherein a length of a gap (8) is in each case smaller than a length of a longitudinal lever arm (3), and wherein the longitudinal lever arms (4) of the second row are each spaced from one another in the longitudinal direction (L) by gaps (8), wherein a length of a gap (8) is in each case smaller than a length of a longitudinal lever arm (4) is. [7] Shock reducing element (1) according to one of the preceding claims, wherein the longitudinal lever arms (3, 4) and the transverse lever arms (5) each extend straight. [8] Shock reducing element (1) according to one of the preceding claims, wherein the shock reducing element (1) is designed in one piece and / or monolithic. [9] Shock reduction system (1) comprising a plurality of shock reduction elements (1) according to one of the preceding claims, wherein the shock reduction elements (1) are in mechanical operative connection with one another.

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