Leaf spring with spacer

Abstract

Leaf spring (1), in particular trapezoidal spring, parabolic spring or link spring, for use in a wheel suspension of a vehicle, wherein the leaf spring (1) has at least one leaf (2) with a top, a bottom (11), two end sections (4), a central section (5) extending between the end sections (4) and a clamping area (6) preferably arranged centrally in the central section (5), and at least one spacer (3) arranged on the bottom (11) or top in the clamping area (6) of the leaf spring (2), and wherein at least one anti-rotation device (13) is arranged between the leaf spring (2) and the spacer (3), characterized in that the anti-rotation device (13) has a first adhesive layer (14), a further adhesive layer (15) and a compressible layer (16) arranged between the adhesive layers (14, 15).

Description

[0001] The invention relates to a leaf spring, in particular a trapezoidal spring, parabolic spring or link spring, for use in a wheel suspension of a vehicle, wherein the leaf spring has at least one spring leaf with a top, a bottom, two end sections, a central section extending between the end sections and a clamping area preferably arranged centrally in the central section, as well as at least one spacer arranged on the bottom or top in the clamping area of ​​the spring leaf, and wherein at least one anti-rotation device is arranged between the spring leaf and the spacer.

[0002] In order to increase the distance between the springing part of the leaf spring, which consists of one leaf or several interconnected leaves, and the axle located below or above it in conventional wheel suspensions, at least one spacer is arranged between the leaf(s) of the leaf spring and a support or guide of the axle.

[0003] The spacer is preferably connected to the resilient part of the leaf spring, for example via a bolt, and is short compared to the overall length of the leaf spring. It is essentially the same width as the spring leaves or even narrower, so that it does not protrude laterally beyond them and one or more U-bolts can be guided over the connected spring leaves and the spacer during assembly of the leaf spring.

[0004] Before installing the leaf spring with the spacer into a wheel suspension, impacts occurring during transport or improper storage can cause the spacer to twist relative to the rest of the leaf spring, so that sections of the spacer protrude laterally beyond the spring leaves. One solution to prevent this is, for example, the use of an anti-rotation device made of bent sheet metal.

[0005] Such an anti-rotation device is, for example, Z-shaped and has a central section and two side sections adjoining it at right angles and extending in opposite directions. The central section of the anti-rotation device is positioned between the resilient part of the leaf spring and the spacer, or between two leaf sections of the leaf spring. One of the side sections rests against at least one leaf section, and the other side section rests against the spacer—and, if necessary, against further leaf sections—thus forming a positive locking mechanism to prevent rotation.

[0006] It is also conceivable that such an anti-rotation device is U-shaped, comprising a central section and two side sections adjoining it at right angles and running in the same direction. The central section of this anti-rotation device is positioned between two leaves of the leaf spring. The side sections encompass the remaining leaf spring along with the spacer and rest against it laterally, thus forming a positive locking mechanism to prevent rotation.

[0007] However, the production of leaf springs with such anti-rotation devices is complex and expensive, despite the simple design of the devices made from bent sheet metal. This is because the anti-rotation devices described above must be manufactured with exceptional precision, as even slight deviations from tolerance specifications or minor material defects can make it extremely difficult or even impossible to install the anti-rotation devices during leaf spring assembly, or they can be damaged or destroyed during assembly or transport. Furthermore, leaf springs with such anti-rotation devices are heavier because the devices are usually made of metal.

[0008] DE 10 2015 104 215 A1, DE 10 2010 010 987 A1 and DE 10 2018 200 323 A1 disclose a leaf spring for use in a wheel suspension of a vehicle.

[0009] The invention is based on the objective of providing a leaf spring of the aforementioned type that does not exhibit the disadvantages of the prior art. In particular, in the leaf spring according to the invention, a spacer arranged on a spring leaf is secured against rotation by at least one anti-rotation device, which is particularly simple and easy to manufacture and install, and which also weighs less than anti-rotation devices made of sheet metal.

[0010] The problem underlying the invention is solved according to the invention with a leaf spring which has the features of claim 1 and with a wheel suspension of a vehicle having the features of claim 10.

[0011] Preferred and advantageous embodiments of the invention are the subject of the dependent claims.

[0012] According to the invention, the anti-rotation device comprises a first adhesive layer, a further adhesive layer and a compressible layer arranged between the adhesive layers.

[0013] The surfaces of the leaf spring and the spacer, which exhibit surface irregularities due to manufacturing or machining, cannot be aligned perfectly parallel to each other because of these irregularities. Consequently, they do not make contact over a full surface, but only in certain areas or even at specific points. In particular, the surfaces are mill-finished when the leaf spring is assembled and therefore exhibit relatively large surface irregularities. A single adhesive layer placed between them can therefore only bond the two surfaces in certain areas, not across the entire surface.

[0014] Advantageously, in the anti-rotation device according to the invention, surface irregularities can be compensated for particularly effectively by means of the more or less strongly compressed compressible layer, so that a substantially area-covering connection between the surfaces can be formed with the help of the two adhesive layers.

[0015] Furthermore, the anti-rotation device according to the invention is particularly lightweight compared to conventional anti-rotation devices, which are made, for example, of sheet metal. This allows the weight of the leaf spring to be reduced.

[0016] A further advantage lies in the fact that the anti-rotation device according to the invention is arranged entirely within the clamping area. For the purposes of the invention, the clamping area is defined as the region of the leaf spring in which the leaf spring is pressed against an axle or axle bolt by axle connection devices, such as two U-bolts or a bolt guided through the spring leaves. Unlike conventional anti-rotation devices, no component of the anti-rotation device that increases the width of the leaf spring, at least in certain areas, projects laterally beyond the spring leaf or the spacer.

[0017] The leaf spring according to the invention can be a multi-leaf spring or a single-leaf spring, optionally with a base leaf. Within the scope of the invention, the upper side of a spring leaf is considered to be the side of the spring leaf that is subjected primarily to tensile stress during use, and the lower side is considered to be the side that is subjected primarily to compressive stress during use.

[0018] In the application area of ​​the invention, a spacer essentially has the main task of increasing the distance between the resilient part of the leaf spring, consisting of at least one leaf, and an axle arranged below or above it. The spacer(s) installed in the leaf spring according to the invention therefore has / have a certain thickness, for example, at least 5 mm. A significantly thinner intermediate plate used in conventional leaf springs is not a spacer within the meaning of the invention.

[0019] Within the scope of the invention, components of the leaf spring are also considered spacers if they primarily serve a purpose other than increasing the distance between the springing part of the leaf spring and the axle, provided they are arranged below or above a leaf spring or another spacer and have a certain thickness, for example, at least 5 mm. One such component is, for example, a roller layer consisting of a metal strip with a connecting element, in particular an eye, formed at one end for connection to a shock absorber.

[0020] A leaf spring according to the invention can have more than one spacer, wherein the two or more spacers are arranged one below the other or above the other. In any case, with more than one spacer, an anti-rotation device according to the invention is provided at least between the spacer arranged on the resilient part of the leaf spring, i.e., on a leaf, and the associated leaf.

[0021] Preferred embodiments include a connection between the spring leaf and the spacer via a connecting element, in particular a screw or bolt, preferably a center bolt. Such a connecting element is, for example, guided through a through-hole in the clamping area of ​​the spring leaf and through another through-hole in the spacer, pressing the spacer against the spring plate. In a multi-leaf spring, each individual spring leaf preferably has a through-hole through which the connecting element is guided. The connecting element presses the components of the leaf spring together.

[0022] Within the scope of the invention, it is also possible that the spring leaf(s) and the spacer(s) are enclosed and pressed together by U-shaped bolts.

[0023] In a preferred embodiment, the connecting element is guided through a further through-hole in the anti-rotation device. In this embodiment, the anti-rotation device preferably covers the entire clamping area, so that a particularly large-area connection is formed between the spring leaf and the spacer.

[0024] In another preferred embodiment, at least one anti-rotation device is arranged between the spring leaf and the spacer on both sides of the connecting element. This simplifies the manufacture and application of the anti-rotation device, since only suitable pieces, for example rectangular ones, without recesses need to be provided and applied between the spacer and the spring leaf.

[0025] Within the scope of the invention, it is preferred that the compressible layer is a porous layer. Preferably, the layer is formed from an elastic plastic, in particular a solidified foam, preferably a polyethylene foam. Such a layer can be compressed particularly strongly, so that even with a small thickness of the anti-rotation device, large unevenness can be compensated for.

[0026] In particular, a preferred embodiment of the invention includes an elastic layer, especially a film, preferably made of plastic or metal, arranged between the first adhesive layer and the compressible layer and / or between the compressible layer and the further adhesive layer. Such a layer prevents the adhesive from the adhesive layers from penetrating the compressible layer, for example, if the latter consists of a porous material such as foam.

[0027] However, within the scope of the invention, it is also possible that the compressible layer is a non-porous and essentially compact layer, for example made of an elastic plastic such as rubber or silicone. An anti-rotation device manufactured with such a layer is indeed compressible by pressing the layer outwards, but it also has the additional advantage that the adhesive layers can be applied directly to the compressible layer without the adhesive being able to penetrate it.

[0028] Preferred embodiments include an anti-rotation element that, in its uncompressed state, is between 0.3 mm and 8.0 mm thick, particularly between 0.4 mm and 5.0 mm, and preferably between 0.5 mm and 2.0 mm. Such anti-rotation elements are thick enough to uniformly fill the gap between the surface of the leaf spring and the spacer attached to it, even with significant deviations from specified manufacturing tolerances. The uncompressed state is understood to be the state of the anti-rotation element in which it is not yet pressed between the surface of the leaf spring and the surface of the spacer, i.e., before the leaf spring according to the invention is fully assembled.

[0029] In a preferred embodiment, the spacer is essentially as wide as the spring leaf mounted on it. In particular, the spacer is essentially as long as the clamping area or shorter than it. This saves as much material and weight as possible while maintaining full functionality.

[0030] However, embodiments are also conceivable in which the spacer, viewed longitudinally along the leaf spring, projects beyond the clamping area. In such embodiments, the spacer can fulfill further functions – in addition to increasing the distance between the spring section of the leaf spring and the axle.

[0031] Within the scope of the invention, it is possible that the leaf spring has a means for connecting it to a vehicle chassis in one or both end sections. Such a connecting means, for example an eye, is preferably formed directly on the leaf or one of the leaves, thereby simplifying the manufacture of the leaf spring. Preferably, the connecting means is a rolled eye formed by rolling in one of the end regions, whereby a gap may be formed between the end face of the rolled-in end region and the upper or lower surface of the leaf.

[0032] In a preferred embodiment, at least the leaf(s) of the leaf spring are made of steel, in particular spring steel. Preferably, the spacer(s) are also made of steel, in particular spring steel. Due to the anti-rotation device according to the invention, a steel leaf spring weighs less than a steel leaf spring with a conventional anti-rotation device, thus saving material and costs.

[0033] It is also conceivable that the spacer(s) are made of light metal, in particular aluminum, or an alloy. Furthermore, the spacer(s) can be cast, sintered, forged, or manufactured by a machining process.

[0034] Within the scope of the invention, an embodiment is also possible in which one or more parts of the leaf spring, in particular the leaf / leaves and / or the spacer(s), are made of plastic, in particular of fiber-reinforced plastic, preferably of glass fiber reinforced plastic (GFRP).

[0035] A wheel suspension of a vehicle according to the invention comprises at least one leaf spring according to the invention. Such a wheel suspension can be assembled particularly quickly and effectively, since the risk of the spacer being twisted relative to the rest of the leaf spring is eliminated, and the leaf spring installed therein therefore has no components projecting beyond the width of the spring.

[0036] Further details, features and advantages of the invention will become apparent from the following description with reference to the accompanying drawing, in which preferred embodiments are shown. It shows: Fig. 1 an isometric view of a leaf spring according to the invention with a detail of the leaf spring in a sectional view, Fig. 2 an embodiment of an anti-rotation device applied to a spacer, and Fig. 3 another embodiment of the anti-rotation device applied to the spacer.

[0037] Fig. Figure 1 shows a leaf spring 1 according to the invention with two spring leaves 2 and a spacer 3.

[0038] Each leaf spring 2 has two end sections 4, a central section 5 arranged between them, and a clamping section 6 located centrally in the central section 5. The clamping section 6 is the area in which the leaf spring 1 is pressed against an axle or axle bolt by axle connection devices (not shown), such as two U-bolts. The spacer 3 is essentially as long as the clamping section 6.

[0039] The spring leaves 2 and the spacer 3 are connected and pressed together via a connecting element 7, which is guided through through holes 8 in the clamping areas 6 of the spring leaves 2 and through another through hole 9 in the spacer 3.

[0040] Between a lower side 11 of one leaf 2 and a upper side 12 of the spacer 3 there is at least one Fig. 1 non-visible anti-rotation device 13 arranged.

[0041] The enlarged detail of the Fig. Figure 1 shows a section through the spacer 3, the anti-rotation device 13 and the spring leaf 2 arranged on the spacer 3 in the area of ​​the underside 11 of the spring leaf 2 and the top side 12 of the spacer 3.

[0042] The anti-rotation device 13 has - as shown - at least a first adhesive layer 14 which is glued to the underside 11 of the leaf spring 2, a further adhesive layer 15 which is glued to the top side 12 of the spacer 3, and a compressible layer 16 arranged between the adhesive layers 14, 15.

[0043] The Fig. 2 and Fig. Figure 3 shows two possible embodiments of how the spacer 3 can be secured against rotation on the spring leaf 2. For better illustration, the figures are shown below. Fig. 2 and Fig. 3 the spring leaves 2 and the connecting element 7 are not shown.

[0044] At the in Fig. In the embodiment shown in Figure 2, a single anti-rotation device 13, extending substantially over the entire top surface 12 of the spacer 3, is arranged between the spacer 3 and the clamping area 6 of the spring leaf 2 (not shown).

[0045] In this embodiment, the anti-rotation device 13 has a further through-hole 17 which is suitable in shape and size for the through-holes 8 of the leaf springs 1 and for the further through-hole 9 of the spacer 3, through which the connecting element 7 is guided.

[0046] At the in Fig. In the embodiment shown in Figure 3, two anti-rotation devices 13 are arranged between the spacer 3 and the clamping area 6 of the spring leaf 2 (not shown), each applied laterally to the further through-hole 9 of the spacer 3.

[0047] In the illustrated embodiment, the two anti-rotation devices 13 extend essentially over the entire width of the spacer 3 or the clamping area 6 of the leaf spring 1 (not shown).

[0048] It is also conceivable to have embodiments in which more than two anti-rotation devices 13 are provided between the spacer 3 and the leaf spring 2. These anti-rotation devices 13 can be designed with or without further through-holes 17 and can be arranged arbitrarily in the clamping area 6 between the underside 11 of the leaf spring 2 and the top side 12 of the spacer 3, for example, in a strip-like and parallel arrangement in the longitudinal or transverse direction of the leaf spring, or in a point-like or patterned manner.

Claims

[1] Leaf spring (1), in particular a trapezoidal spring, parabolic spring or trailing arm spring, for use in a wheel suspension of a vehicle, wherein the leaf spring (1) has at least one spring leaf (2) with an upper side, a lower side (11), two end sections (4), a central section (5) extending between the end sections (4) and a clamping area (6) preferably arranged centrally in the central section (5), as well as at least one spacer (3) arranged on the lower side (11) or upper side in the clamping area (6) of the spring leaf (2), and wherein at least one anti-twist device (13) is arranged between the spring leaf (2) and the spacer (3), characterized by that the anti-twist device (13) has a first adhesive layer (14), a further adhesive layer (15) and a compressible layer (16) arranged between the adhesive layers (14, 15). [2] Leaf spring according to claim 1, characterized bythat one anti-twist device (13), two anti-twist devices (13) or more anti-twist devices (13) is / are arranged at least over part of the surface between the spring leaf (2) and the spacer (3). [3] Leaf spring according to claim 1 or 2, characterized by that the spring leaf (2) is connected to the spacer (3) via a connecting element (7), in particular a screw or a bolt, wherein the connecting element (7) is guided through a through hole (8) in the clamping area (6) of the spring leaf (2) and through a further through hole (9) in the spacer (3) and presses the spacer (3) towards the spring plate (2). [4] Leaf spring according to claim 3, characterized by that the connecting element (7) is guided through a further through hole (17) of the anti-twist device (13). [5] Leaf spring according to claim 3 or 4, characterized bythat at least one anti-twist device (13) is arranged between the spring leaf (2) and the spacer (3) on both sides of the connecting element (7). [6] Leaf spring according to one of claims 1 to 5, characterized by that the compressible layer (16) is a porous layer, preferably an elastic foam layer. [7] Leaf spring according to one of claims 1 to 6, characterized by that an elastic layer, in particular a film, preferably made of plastic or metal, is arranged between the first adhesive layer (14) and the compressible layer (16) and / or between the compressible layer (16) and the further adhesive layer (15). [8] Leaf spring according to one of claims 1 to 7, characterized by that the anti-twist device (13) in the uncompressed state is between 0.3 mm and 8.0 mm, in particular between 0.4 mm and 5.0 mm, preferably between 0.5 mm and 2.0 mm, thick. [9] Leaf spring according to one of claims 1 to 8, characterized by that the spacer (3) is as wide as the spring leaf (2) arranged thereon and / or that the spacer (3) is substantially as long as the clamping area (6) or shorter than the clamping area (6) or longer than the clamping area (6). [10] Wheel suspension of a vehicle, wherein the wheel suspension comprises at least one leaf spring (1) according to one of claims 1 to 9.

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