Metal air spring corrugated pipe

Abstract

The invention relates to a retractable air spring bellows (100) with an outer metal bellows hose (111) and an inner metal bellows hose (112), which are coupled by a connecting sleeve (120). In order to stabilize the movement, guide elements (161, 162) are provided, which limit the deviation of the movement of the inner and / or outer metal corrugated hose (111, 112) from the axial direction (X). The guide element may, for example, comprise spacer elements (161, 162) arranged between the connecting sleeve (120) on the one hand and the outer or inner metal corrugated hose on the other hand.

Description

Technical Field

[0001] This invention relates to a retractable air spring bellows with metal components. Background Technology

[0002] A retractable air spring bellows is known from document US11401994B2, which comprises two metal bellows telescopically arranged between each other. A problem with this arrangement is that instability can occur during the movement of the metal bellows, potentially impairing function and leading to damage.

[0003] Furthermore, an air spring bellows housed in an outer casing is known from document CN1178171A. Further embodiments of the air spring bellows are described in documents DE811893B, DE102011053131A1, DE102010037162B4, and DE102008001297A1. Summary of the Invention

[0004] In this context, the object of the present invention is to provide a retractable air spring bellows with metal components, which has improved operating characteristics and enhanced long-term stability.

[0005] This objective is achieved by an air spring bellows having the features of claim 1. Advantageous designs are contained in the dependent claims.

[0006] The air spring bellows according to the present invention comprises (at least) the following components: - At least one first metal corrugated hose, which, based on its arrangement, is hereinafter referred to as the "outer metal corrugated hose".

[0007] - At least one second corrugated metal hose, which is arranged at least partially coaxially within the inner cavity of the outer corrugated metal hose, such that it overlaps the outer corrugated metal hose axially in the overlapping area and forms a retractable assembly. Based on its arrangement, the second corrugated metal hose is hereinafter referred to as the "inner corrugated metal hose".

[0008] - A connecting element, which will be referred to hereafter as a "connecting sleeve" without limiting its versatility, wherein the connecting sleeve extends between the outer and inner corrugated metal hoses in the aforementioned overlapping area and connects the two corrugated metal hoses to each other.

[0009] The air spring bellows is characterized by having a guiding element that limits the movement and axial deviation of the outer and / or inner metal bellows hoses.

[0010] The deviation limited by the guiding element can be particularly lateral or torsional in terms of axial direction. Here, the limitation of deviation can also include (almost) complete prevention of such deviation. The axial direction corresponds to the spring direction of the air spring bellows and is usually predetermined by the configuration of the metal bellows (as its axis of symmetry or central axis). Limiting motion deviation improves the operating characteristics of the air spring bellows and prevents damage.

[0011] Within the scope of this application, a “metal corrugated hose” (or “corrugated pipe”) should generally be understood as a tubular hose of metal, whose geometry is distinguished from a simple cylinder by the presence of at least one radially inwardly pointing and circumferentially extending constriction. Typically, such a constriction is not locally restricted but extends around the hose axis at its periphery. Constrictions may be not only annularly closed but also spirally encircling.

[0012] For functional use as an air spring bellows, the inner and outer metal bellows hoses and connecting sleeves are typically implemented and airtightly connected to each other. However, the scope of this invention also includes other applications of the device referred to as an "air spring bellows" that may not require a sealed, low-occlusion interior, thus in which case the components or their connections do not need to be airtight.

[0013] Furthermore, more than two metal bellows can be provided, which can be connected in series or combined in parallel with each other in a telescopic arrangement. In particular, there can be multiple pairs of outer and inner metal bellows, which are interconnected via associated connecting sleeves. In this way, the ratio between the minimum and maximum lengths of the air spring bellows can be structurally set approximately arbitrarily.

[0014] The connecting sleeve is preferably connected to the upper axial end of the outer corrugated metal hose and the upper and lower axial ends of the inner corrugated metal hose (wherein the terms "upper" and "lower" are relative or valid in the corresponding orientation of the air spring bellows). Because the overlapping area between the inner and outer corrugated metal hoses typically extends between these two ends, the connecting sleeve covers the entire overlapping area in this case. At the maximum possible compression of the air spring bellows, the inner and outer corrugated metal hoses are completely juxtaposed, meaning the overlapping area extends along the entire axial length of the air spring bellows.

[0015] The guide element can be designed and arranged in different ways, and it can consist of one or more parts. According to a preferred embodiment, the guide element is at least partially (preferably completely) arranged within the outer corrugated metal hose and / or the inner corrugated metal hose. This protects it from harmful environmental influences such as contamination and corrosion, which contributes to the service life of the air spring bellows.

[0016] According to another preferred design, the guiding element includes a linear guide in the axial direction. In other words, lateral deviation in this direction is (completely or partially) limited. Additionally or alternatively, torsional movement (rotation) about the axial direction can also be limited by the linear guide. A linear guide without torsional limitation is produced, for example, by two concentric and telescoping tubes with circular cross-sections inserted into each other. When the tubes have non-circular cross-sections, the linear guide further limits torsional movement.

[0017] In another embodiment, the guide element is connected to the outer or inner side of the outer and / or inner corrugated metal hose. In this way, force can be applied directly to that side, thus limiting lateral movement, for example. The guide element can be specifically connected or fixedly coupled to a defined position on the outer or inner side, allowing it to move axially with that position. The guide element can, for example, be a body that is shaped to fit the corrugated metal hose, for example, by engaging it into a recess in the corrugated metal hose. Details of such a shaped-fit connection can be found, for example, in patent DE102010037162B4.

[0018] Furthermore, the guide element is preferably slidable along a sliding surface when the air spring bellows is compressed or stretched axially. The sliding surface can then be a guide groove, which achieves the desired motion restriction. Additionally, the contact between the guide element and the guide groove reduces frictional work, which has a positive impact on the damping characteristics of the air bellows.

[0019] Especially when there is sliding contact between the guide element, connecting sleeve, outer corrugated metal hose and / or inner corrugated metal hose, the corresponding contact surfaces may advantageously have a coating that reduces friction and / or wear. This coating may preferably comprise or constitute at least one of the following materials: high-quality steel, steel, zinc, zinc phosphate, aluminum alloy, copper, titanium, tantalum, nickel-based alloy, graphite, aramid (e.g., Kevlar®), brass, bronze, (hexagonal) boron nitride, and / or molybdenum disulfide.

[0020] According to another preferred embodiment, the guide element may be arranged between the connecting sleeve on one side and the outer and / or inner corrugated metal hose on the other side. In this case, the guide element allows force transmission between at least one of the connecting sleeve and the corrugated hose without creating direct contact between these components. This particularly reduces lateral bending movement of the corrugated hose without creating abrasive or damped direct contact.

[0021] According to another design of the invention, the air spring bellows has a limiting element for limiting the maximum extension of the air spring bellows. Here, the limiting element can extend particularly within the interior of the internal metal bellows hose. It can be implemented, for example, by a rope, chain, etc., extending between the foot and head points of the air spring bellows. The limiting element prevents excessive extension of the air spring bellows, which could potentially damage it.

[0022] In another improvement of the invention, at least one end of the air spring bellows has a connecting plate. Such a connecting plate enables the (air)tight sealing of the air spring bellows and provides a defined port for connecting to other components, such as a resilient motor vehicle or machine. Preferably, the connecting plate includes locking bolts for the orientation of the air spring bellows relative to its surroundings.

[0023] If the air spring bellows is to be used in the form of an air spring, the inner cavity of the metal bellows typically forms a closed volume filled with gas under overpressure. To generate and / or regulate gas pressure, the air spring bellows preferably has an interface through which a pressure medium (e.g., compressed air) can be supplied to the inner cavity. The interface for the pressure medium may, for example, be located in one of the aforementioned connecting plates.

[0024] External or internal corrugated metal hoses can be, in particular, corrugated tubes, wound corrugated tubes, or diaphragm corrugated tubes. The term "corrugated tube" generally refers to a hose with a wavy outer profile, wherein the difference between the minimum inner diameter and the maximum outer diameter is relatively large (e.g., at least 5% of the outer diameter, preferably at least 10% lower). Corrugated tubes are typically manufactured from tubes by internal high-pressure forming in conjunction with a compression operation. Wound corrugated tubes and diaphragm corrugated tubes are rotationally symmetrical or helical wavy elements welded in the profile region, having waves or helical waves imprinted perpendicular to the axis of rotation. Wound corrugated tube structures are preferably form-fitted hooked or overlapping or material-fitted welded. Such elements are illustrated, for example, in documents DE102008001297A1 or DE102011053131A1, which are fully incorporated herein by reference.

[0025] Air springs and their components (metal bellows, connecting sleeves, etc.) may have a circular or non-circular (elliptical or polygonal) cross-section perpendicular to the axial direction. Attached Figure Description

[0026] The invention will now be described in detail with reference to an embodiment and the accompanying drawings. Wherein: Figure 1 A schematic cross-section showing half of the retractable air spring; Figure 2Alternative implementations with limiting elements as linear guides are shown. Figure 1 The segment in the middle. Detailed Implementation

[0027] In the prior art, rolling or folding bellows are typically used as air spring systems depending on the application area. For example, rolling bellows (combined with rolling pistons and pressure plates) are preferred in the automotive and commercial vehicle sectors. Here, the bellows are typically made of a rubber blend NR (natural rubber) / SBR (styrene-butadiene rubber) with additional reinforcing fabric.

[0028] In the commercial vehicle sector, rolling bellows allow for at least + / -100mm of spring travel with a compact installation height due to their structure. In the motor vehicle sector, + / -50mm of spring travel is common. Furthermore, even higher static lift can be achieved when stationary, which is necessary, for example, to adapt the vehicle to varying load-bearing edges.

[0029] A disadvantage of existing technology is that rubber ages due to factors such as sunlight, ozone, engine or exhaust heat. The corrugated pipe walls then harden and become brittle, and there is a risk of cracking, especially in areas of rolling folds.

[0030] Therefore, the use of bellows made of metal is highly desirable. Metal has higher compressive strength than rubber, making higher burst pressure and more compact components possible. Furthermore, metal is recyclable compared to natural rubber.

[0031] Due to the aforementioned advantages, an air spring bellows should be provided for use, which achieves the same spring travel as conventional rubber bellows in a comparable installation space by using multiple compact, flexible metal hoses / metal bellows. Preferably, at least two metal bellows, metal hoses, and / or diaphragm bellows should be coaxially inserted into each other to achieve a telescopic structure. This telescopicity allows for a compact installation height and ample spring travel.

[0032] exist Figure 1 The figure shows a cross-section through one embodiment of the air spring bellows 100 according to the invention. Here, only half of the device is shown, which can be set up approximately rotationally symmetrical about the vertical "axis" X in the figure.

[0033] The air spring bellows 100 comprises two telescopically nested metal bellows: an outer metal bellows 111 and an inner metal bellows 112 arranged coaxially therein. A suitable airtight, helically wound metal bellows (which has greater flexibility than conventional metal bellows) is known, for example, from document DE102008001297A1. This flexibility allows for greater tension and compression of the component from a neutral position (typically approximately 20% in the compression and tension directions).

[0034] The upper end of the outer metal bellows 111 (in the figure) is connected to the lower end of the inner metal bellows 112 via a preferably rigid connecting sleeve 120. The Z-shaped connecting sleeve 120, with its axially extending cylindrical sheath, covers the overlapping area between the inner and outer metal bellows in its cross-section. Furthermore, the connecting sleeve 120 serves to transmit movement of the inner metal bellows 112 to the outer metal bellows 111.

[0035] The connecting sleeve 120 can be implemented as a pressed part, a drawn part, or a machined part, for example. It is preferably made of metal, however, it can also be made of plastic and / or have a coating that reduces wear and friction.

[0036] The connecting sleeve 120 can have different shapes depending on the number of metal bellows. In the embodiment shown, it has a Z-shaped profile.

[0037] The connecting sleeve 120 is connected to a corresponding metal bellows in its axial end region. This connection can be achieved through a form fit (e.g., pressing, rolling), a material fit (e.g., welding, brazing, bonding), or a force fit. For application as an air spring, the connection must be airtight.

[0038] The total length L of the air spring bellows 100 N It can vary depending on its extension or compression in the axial direction X. The length L of the overlapping region. B The variable lengths L1 and L2 above and below it constitute the total length L of the air spring bellows 100. N In the maximum compression state of the air spring bellows, lengths L1 and L2 can be reduced to zero, wherein the two metal bellows 111 and 112 are parallel to each other and completely surround or are located inside the connecting sleeve 120. Overlap length L B The length should be chosen as large as possible to achieve the smallest possible installation height. However, it is only allowed to be chosen so large that the resulting lengths L1 and L2 in the stationary state are greater than the system's maximum compression stroke.

[0039] As an alternative to the illustrated embodiment, more than two metal bellows (and connecting sleeves) can be coaxially inserted into each other (three, four, ..., n metal bellows). The more bellows inserted into each other, the greater the spring travel and the larger the outer diameter.

[0040] Furthermore, the arrangement of the bellows can be achieved side by side (parallel), sequentially, or both side by side and sequentially.

[0041] If all metal bellows are implemented with the same length, the bellows with the smallest diameter typically has the greatest axial and lateral (perpendicular to the central axis X) stiffness. The diameter and bellows length can be coordinated so that two bellows with different geometries have the same axial and lateral stiffness.

[0042] On their lower or upper sides, corrugated metal pipes 111 and 112 are respectively connected to connecting plates 140 or 130, which in turn may be connected to the surrounding environment (not shown in detail). The connection to the connecting plates can be achieved through shape-, material-, or force-fitting methods, and in a hermetically or liquid-tight manner. In a preferred embodiment, the connecting plates are joined by a welding process.

[0043] In principle, the application areas of the air spring bellows 100 are variable, including applications where the air spring bellows (as opposed to its name) does not function as an air spring. In the latter case, the interior of the air spring bellows does not need to be airtight relative to the surrounding environment. However, if the air spring bellows is to be used as an air spring, the metal bellows 111, 112, the connecting sleeve 120, the connecting plates 130, 140, and the connections between these components should be airtight with each other. This allows the gas inside the assembly to be compressed, thus generating the desired elastic spring force.

[0044] The metal bellows 111 and 112 are preferably sized and constructed such that they have the same large spring constants c1 and c2. This has the advantage that the elongation is evenly distributed on the two bellows and the spacing L1 and L2 are equal.

[0045] The upper connecting plate 130 may optionally have locking bolts 131 to facilitate orientation relative to the surrounding environment.

[0046] The lower connecting plate 140 may have a compressed air inlet pipe 141 for connecting to an external compressed air source, as shown. In this way, the space that can be airtightly surrounded by the metal bellows can be limited to an internal pressure P. i Loading. The limited internal pressure causes the metal bellows to elongate.

[0047] The metal bellows 111 and 112 have a rest length in their unloaded state. If they are compressed relative to this rest length, they can cause a lateral deflection (buckling). To limit or completely prevent this, at least one guiding element is provided in the air spring bellows 100, which limits or completely prevents the lateral and / or torsional movement of the metal bellows.

[0048] exist Figure 1 In the example shown, the guiding element is implemented by two spacer elements 161 and 162, arranged either between the inner side of the outer bellows 111 and the connecting sleeve 120, or between the connecting sleeve 120 and the outer side of the inner bellows 112. These can be, for example, a metal braided strip made of relatively soft, low-friction non-ferrous metals such as cadmium, cobalt, copper, nickel, lead, tin, and zinc, which can slide along the connecting sleeve 120 with less friction and wear. Alternatively, high-quality corrosion-resistant and heat-resistant steel can be used. The spacer elements prevent lateral bending of the bellows 111 and 112, thus achieving clean guidance. The braided strip is preferably geometrically adapted to the contour of the bellows' waves so that it can be positioned in a defined and shape-fitting manner. It is compressible to a limited extent and thus does not significantly affect the movement of the bellows. Alternatively, the spacer element can also be made "robustly" of plastic or non-ferrous metals (copper, brass, bronze, nickel, lead, tin, zinc, etc.).

[0049] To prevent excessive stretching of the air spring bellows 100 in the axial direction X and thus plasticization of the bellows material, a centrally located restraining element 150 may be provided. In the illustrated embodiment, this is a flexible (cable) rope extending between the lower connecting plate 140 and the upper connecting plate 130, and its extended length presupposes the maximum stretch of the air spring bellows. The air spring bellows 100 in... Figure 1 The neutral position shown has a length L N The metal bellows 111 and 112 are in length L B They overlap (corresponding to the height of the connecting sleeve 120) and extend beyond the overlapping area with a variable length L1 or L2.

[0050] An alternative embodiment of the limiting and guiding element 163 is in Figure 2 As shown in the figure. This figure illustrates something similar to... Figure 1 The cross-section, however, is not shown. The guide element 163 is implemented as a linear guide unit and is formed, for example, by two slotted tubes 163a, 163b fixed at upper or lower connecting plates 130, 140 and guided in each other, connected by stop bolts. This enables axial and torsional limitation of movement and avoidance of excessive bending.

[0051] In operation of the air spring bellows 100, an elastic compressible medium (gas, air) is introduced through the lower connecting plate 140 to pressure the inner cavity of the metal bellows, for example, an operating pressure of approximately 7 bar. This internal pressure creates forces on the inner surfaces of the upper and lower connecting plates 130 and 140. If this component is not externally constrained, this results in a length L... N The member elongates and increases. If the member is installed between two restrictive frame structures, the resulting forces are absorbed by it and generate reaction forces in the frame structures. Therefore, no change in the member's length occurs.

[0052] If the air spring bellows 100 is subjected to external forces due to the characteristics of the road section during operation, the metal bellows 111 and 112 are compressed and their internal volume changes. The change in volume leads to a change in internal pressure (in this case, an increase).

[0053] For helical bellows, the pitch of the coils can cause lateral bending of the sleeve when the internal pressure increases. Such bending is suppressed by the parallel arrangement of the bellows in conjunction with supporting spacer elements 161, 162.

[0054] Additional secondary damping of the system can be achieved through indirect frictional contact between the connecting sleeve 120 and the metal bellows, thereby affecting the frequency characteristics of the metal air spring.

[0055] Optionally, a throttle valve (not shown) may also be provided between the two metal bellows to affect or suppress the exchange of fluid between the chambers and thus obtain internal damping of the system.

[0056] The described air spring bellows can be used, for example, in commercial vehicles (in light, medium, and high-load applications) and in motor vehicles. The use of air springs is particularly advantageous in battery electric vehicles (BEVs) due to the increased vehicle weight in battery-powered vehicles.

[0057] Because air spring bellows implement axial movement in their primary function, industrial applications such as linear guides for machine components and / or elastic suspensions for machine components are also possible.

Claims

1. Air spring bellows (100), comprising - an outer metal bellow hose (111); - an inner metal bellow hose (112) arranged at least partially coaxially in an inner lumen of the outer metal bellow hose (112) such that it overlaps the outer metal bellow hose in an overlap region (LB) in axial direction (X) and forms a telescopic assembly; - a connecting sleeve (120) extending between the inner metal bellow hose (112) and the outer metal bellow hose (111) in the overlap region (LB) and connecting them to each other; characterized in that a guiding element (161, 162, 163) limiting a deviation of the movement of the outer metal bellow hose (111) and / or the inner metal bellow hose (112) from the axial direction (X).

2. The air spring bellows (100) of claim 1, wherein, The guiding element (161, 162, 163) is arranged in an inner lumen of the outer metal bellow hose (111) and / or the inner metal bellow hose (112).

3. The air spring bellows (100) of claim 1 or 2, characterized in that The guiding element comprises a linear guide (163) in the axial direction (X).

4. The air spring bellows (100) according to at least one of the preceding claims, characterized in that The guiding element (161, 162) is coupled to an inner side or an outer side of the inner metal bellow hose (112) or the outer metal bellow hose (111).

5. The air spring bellows (100) according to at least one of the preceding claims, characterized in that The guiding element (161, 162) is slidable along a sliding surface.

6. The air spring bellows (100) according to at least one of the preceding claims, characterized in that The guiding element (161, 162) is arranged between the connecting sleeve (120) and the outer metal bellow hose (111) and / or the inner metal bellow hose (112).

7. Air spring bellows (100) according to at least one of the preceding claims, characterized in that It has a limiting element (150) for limiting the maximum axial extension, which preferably extends in the interior of the inner metal bellow hose (112).

8. The air spring bellows (100) according to at least one of the preceding claims, characterized in that At at least one axial end of the air spring bellows a web plate (130, 140) is arranged, which preferably has a locking bolt (131) for the orientation of the air spring bellows.

9. Air spring bellows (100) according to at least one of the preceding claims, characterized in that It has an interface (141) for supplying pressure medium.

10. Air spring bellows (100) according to at least one of the preceding claims, characterized in that The outer metal bellow hose (111) and / or the inner metal bellow hose (112) is a wave bellow, a convoluted bellow or a diaphragm bellow.

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