DE102016013347A1 - Lifetime resistant clamping connection of a plastic leaf spring - Google Patents

Abstract

The invention relates to an arrangement (10) for life-proof clamping connection of a plastic leaf spring (12) with a vehicle axle (18) or with a vehicle body part (18), wherein the leaf spring (12) between a saddle element (14) and a plate element (16) is arranged, the saddle element (14) with the vehicle axle (18) or the vehicle body part (18) is connected and four support areas (20a, b, c, d), each having an opening, characterized in that the plate element (16) comprises, on its surface facing away from the leaf spring (12), two guide grooves (22a, b) extending transversely to the longitudinal extension of the leaf spring (12) in each guide groove (22a, b) of the plate element (16 ) in each case a clamping bracket (24a, b) extends, which with legs (26a, c; 26b, d) through two openings (28a, c, 28b, d) of the support areas (20a, b, c, d) of the saddle element ( 14) and further by elastic compression elements (30a, c; 30b, d) only extends, wherein the end portions of the legs (26a, c; 26b, d) each have a screw thread (32a, c; 32b, d) for engagement in a mating thread (34a, c; 34b, d) of a fixing means (36a, c, 36b, d), and by means of the fixing means (32). 36a, c, 36b, d) relative to the plate element (16) tensioned straps (24a, b) and by the fixing means (36a, c, 36b, d) on the at the support areas (20a, b, c, d ) on compression element (30), a clamping force between the plate element (16) and the saddle element (14) is constructed.

Description

The invention relates to an arrangement for life-time clamping connection of a plastic leaf spring comprising a vehicle action a vehicle body part, as well as a vehicle comprising such an arrangement.

As leaf springs for vehicles, especially motor vehicles, springs are increasingly used, which are not made entirely of metal, but are metal-free and include plastic components. However, plastic is a material that plastically deforms during a load depending on time and temperature. Since the leaf springs must be connected by means of a clamping connection with an axle or other body part of a respective vehicle, the plastic deformation leads to set losses and thus to the undesirable effect that the originally applied clamping force is gradually getting smaller. In contrast to metal springs, where the originally applied clamping force is maintained over the life of the vehicle, clamping connections in leaf springs with plastic components are not life-time for this reason.

To solve this problem is disclosed in the publication EP 2365229 A2 a leaf spring application proposed in which a two-part leaf spring holder from above and below a corresponding leaf spring engages and between the leaf spring holder and the leaf spring two elastomer body are arranged. In view of the prestressed elastomer body is to be achieved that occurring settling losses are largely compensated. Nevertheless, there is still a need for alternative solutions to control and, if possible, minimize set-up losses, thereby providing life-time clamp connections.

The object of the invention is now to provide appropriate solutions.

The invention results from the features of the independent claims. Advantageous developments and refinements are the subject of the dependent claims.

The object is achieved in a first aspect by an arrangement for life-permanent clamping connection of a plastic comprehensive leaf spring with a vehicle axle or with a vehicle body part, wherein the leaf spring between a saddle member and a plate member is arranged, further wherein the saddle member with the vehicle -Axis or the vehicle body part is connected and four support areas, each having an opening comprises, and further wherein the plate member on its side facing away from the leaf spring surface comprises two transverse to the longitudinal extent of the leaf spring guide grooves, in each guide groove of the plate member each one Clamp extends, which extends with legs through two openings of the support portions of the saddle element and further by elastic compression elements, the end portions of the legs each have a screw thread for engagement in a mating thread of fixatives aufwei sen, and by means of the tensioning means loaded by the fixing means relative to the plate member on the tension and loaded by the fixing means on the pressure applied to the support areas compression elements saddle element a clamping force between the plate member and the saddle element is constructed.

As soon as settling phenomena occur in the plastic, which would reduce the clamping force, this makes it possible to shorten the tension straps loaded on the train and / or expand the compressive elements subjected to pressure, whereby the loss of the clamping force caused by the settling phenomena is at least partially or completely compensated. Thus, it can be advantageously ensured that the clamping force of the arrangement does not drop below its minimum value over its planned service life, which is required for the clamping connection, and is therefore life-long.

The clamping connection is preferably used for a center clamping of the leaf spring.

In particular, two clamping straps are used for the clamping connection, so that the plate element correspondingly has two guide grooves, however, additional clamping straps can still be used, each additional clamping bracket requiring an additional guide groove. Alternatively, however, the brackets can also be replaced by other means and / or be combined in the area of the panel member by other means, which the person skilled in the art can appropriately select in the light of the disclosure made herein. Non-limiting examples of this are tension bands with a flat portion at least in the region of the surface of the plate element facing away from the leaf spring, for example clamping bands made of metal, plastic or a plastic / fiber composite. Depending on the shape of the means chosen, the surface of the plate element may also be modified. For example, if flat clamping bands used, then the plate member does not necessarily need to have guide grooves, but only needs to be shaped so that no slipping of the clamping bands is possible.

According to one embodiment, the mating thread is provided by a nut as a fixing means, wherein the end portions of the legs extend beyond the upsetting elements. Accordingly, the mating thread of the nut engages in the screw thread of the respective leg and advantageously allows for a tightening of the screw thus formed, first a contact structure between the plate member and the leaf spring and between the saddle member and the leaf spring, and in a further tightening the structure of a tensile stress on the clamping bracket and a compressive stress on the compression elements.

According to further embodiments, the compression element is a helical compression spring, an evolute spring, an annular spring, a plate spring or a compression sleeve. In a preferred embodiment, there is a compression sleeve, which consists for example of a material of the strength class 10.9, such as a metal of this strength class, for example of steel or aluminum. The same materials can also be used for the clamps. The tension bow and the compression sleeve are preferably made of the same material, for example of a material of strength class 10.9, such as a metal of this strength class. Each leg can be assigned independently of the other legs a freely selected compression element, but preferably for all legs upsetting elements of the same type are used. In all of these examples, the fixing means may be a nut, wherein the compression member between the respective support region and the mother is loaded on pressure.

In another embodiment, the compression member is a compression sleeve, and the counter thread is provided by an end portion of the compression sleeve. Accordingly, the mating thread simultaneously also constitutes the fixing means. The tightening of the screw connection takes place by turning the compression sleeve until it rests against the corresponding support region, and beyond, until there is sufficient tension on the clamping bracket and / or sufficient pressure on the compression sleeve beneath the latter elastic deformation is constructed.

The plate member and / or the saddle member may be made of an elastic material and thus contribute to the construction of a pressure. Advantageously, however, opens up the possibility in one embodiment, without using an elastic plate member and / or without an elastic saddle element. According to a particular embodiment, the plate member and the saddle member are not made of an elastomer, but of a metal, wherein preferably the compression member is also made of a metal, so that in turn settling of elastomers can not occur.

According to one embodiment, the leaf spring comprising a plastic is a composite spring comprising at least one plastic, for example a composite spring made of plastic and glass fiber, a composite spring made of plastic and carbon fiber, or a composite spring made of plastic and both fiberglass and carbon fiber. According to one embodiment, the compression element is a compression sleeve, wherein its ratio between the longitudinal extent and transverse extent is at least 2: 1, preferably at least 3: 1.

The clamping force in the arrangement according to one embodiment is at least twice the minimum force required for the fixation of the leaf spring between the saddle element and the plate element, for example 2.3 times to 3.6 times this minimum force. Thus, even after a setting behavior of the plastic, a sufficient reserve of clamping force is kept available in order to maintain the minimum clamping force required for the operation of the arrangement over its service life. For example, the minimum clamping force is in the range of 28 kN to 30 kN, and the applied clamping force at the beginning of the life of the assembly in the range of 70 kN to 100 kN, to ensure below the minimum clamping force over a lifetime of 10 years.

In a further aspect, the object is achieved by a vehicle, in particular by a motor vehicle, which comprises an arrangement as described herein. Accordingly, such arrangements in such vehicles can ensure that the clamping connections between respective leaf springs and vehicle axles or vehicle body panels are durable.

Further advantages, features and details will become apparent from the following description in which - where appropriate, with reference to the drawings - at least one embodiment is described in detail. The same, similar and / or functionally identical parts are provided with the same reference numerals.

• 1 einen räumlichen Teilquerschnitt durch eine Anordnung,
• 2 eine räumliche Ansicht der Anordnung,
• 3 die Komponenten einer Anordnung in Explosionsdarstellung,
• 4 ein Diagramm mit Kraftverläufen über die Zeit hinweg.

Show it:

• 1 a partial spatial cross section through an arrangement,
• 2 a spatial view of the arrangement,
• 3 the components of an arrangement in exploded view,
• 4 a graph of force over time.

1 shows a partial cross section through an arrangement 10 , A comparison of the respective perspectives between the 1 . 2 and 3 is possible through the XYZ coordinate systems shown at the bottom left, where in 1 a cross section in the direction of the y-axis is shown. The order 10 includes a lying behind the cutting plane and incomplete leaf spring 12 , The leaf spring 12 is between a saddle element 14 and a plate element 16 arranged, wherein the plate element 16 at his from the leaf spring 12 opposite surface two guide grooves 22a and 22b. Inside the guide grooves 22a and 22b are partially in the sectional plane lying clamping bracket 24a and 24b, passing through the clamps 24a and 24b hidden valleys of the guide grooves 22a and 22b are indicated by dotted lines. The clamps 24a and 24b extend with thighs 26a and 26b through breakthroughs 28a and 28b of support areas 20a and 20b of the saddle element 14 , At the support areas 20a and 20b are upsetting elements 30a and 30b, in the present case as compression sleeves 30a and 30b are formed. The end portions of the legs 26a and 26b each have a screw thread 32a and 32b, which into corresponding mating threads 34a and 34b of fixatives 36a and 36b, which are present as nuts 36a or 36b are formed, intervene. The saddle element 14 is with an axis 18 connected.

With nuts tightened 36a or 36b are the clamping bracket 24a or 24b loaded on train, and continue to be the upsetting elements 30a or 30b compressed and thus burdened with pressure. As a result, a clamping force between the plate member 16 and the saddle element 14 built up. In the event that, in the context of subsidence of the leaf spring 12 undergoes these plastic deformations through which the plate element 16 and / or the saddle element 14 in the leaf spring 12 are pressed, causing the plate element 16 and in the saddle element 14 mediated clamping force would normally decrease, the clamps can 24a and 24b contract and / or the upsetting elements 30a resp. 30b, thereby reducing the amount between the plate element 16 and the saddle element 14 built-up clamping force is prevented or mitigated.

2 shows a spatial representation of the arrangement 10 , The individual components of the arrangement correspond to those in 1 shown components, which now also partially by the selected perspective, a leg 26c of the tension bracket 24a , a further compression element 30c and a further fixing means 36c in the form of a nut are visible. In the absence of a sectional view of non-visible components such as threads are not specifically identified by reference numerals.

3 shows the components in an exploded arrangement, with only the support portion 20d not being directly visible so that its reference arrow ends with a dashed line at the approximate position. In this exploded view, individual components, which are arranged in unexploded state in alignment with each other, not necessarily also arranged in alignment with each other.

4 shows an exemplary diagram with traces of clamping forces over time. The time in years is plotted on the X axis and the clamping force in kilonewtons on the Y axis. F _assembly denotes the clamping force exerted on the leaf spring at the time of assembly of the assembly. The clamping force indicated by a horizontal semicolon line F _min indicates the minimum force required to handle the expected operating loads. Point of time L represents the targeted lifetime of the device in years. After assembly, the actual clamping force decreases over time due to settling phenomena. Curve 2 shown as a dashed line describes the loss of the clamping force in a comparison arrangement in which there is no stress-loaded tension bow and no compression element loaded with pressure. Here, the setting phenomena of the plastic comprehensive leaf spring to the fact that the actual clamping force, which is the curve 2 can be removed, F _min already well ahead of the targeted lifetime L falls below: the loss of clamping force, which is illustrated by the vertical double arrow with dashed line ( ΔF ₂ ) is therefore too high to the clamping force when reaching the targeted life L above the required minimum value F _min to keep. In comparison, the curve 1 shown as a dotted line denotes the course of the clamping force in an arrangement with tension straps loaded with tension and compression elements loaded with pressure. If settling phenomena occur here, then the loss of clamping force is at least partially compensated for by the contracting tensioning straps and / or the upsetting upsetting elements that are dehumidifying. Accordingly, the loss of clamping force in this case, which by the double arrow shown as a dotted line ( ΔF ₁ ) is not so high that before reaching the targeted lifetime L the minimum value for the clamping force F _min would fall below.

Although the invention has been further illustrated and explained in detail by way of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention. It is therefore clear that a multitude of possible variations exists. It is also clear that exemplified embodiments are really only examples that should not be construed in any way as limiting the scope, uses, or configuration of the invention. Rather, the foregoing description and description enable the skilled artisan to practice the exemplary embodiments, and those of skill in the knowledge of the disclosed inventive concept may make various changes, for example, to the function or arrangement of particular elements recited in an exemplary embodiment. without departing from the scope defined by the claims and their legal equivalents, such as further explanation in the specification.

LIST OF REFERENCE NUMBERS

10

arrangement

12

leaf spring

14

saddle member

16

panel member

18

Axle or body part

20a, b, c, d

support area

22a, b

guide

24a, b

tensioning bow

26a, b, c, d

leg

28a, b, d, d

breakthrough

30a, b, c, d

upsetting element

32a, b, c, d

screw thread

34a, b, c, d

mating thread

36a, b, c, d

fixer

F [kN]

Clamping force in kilonewtons

F _assembly

Clamping force at the time of installation

F _min

required minimum clamping force

L

targeted lifetime

Time [years]

Duration of use in years

Curve 1

Course of the clamping force with loaded on train clamps and compression elements

Curve 2

Course of the clamping force without loaded on train clamping bracket and compression elements

ΔF ₁

Loss of clamping force with tension straps loaded on tension and compression elements at time L

ΔF ₂

Loss of clamping force without loaded on train clamps and upsetting elements at time L

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 2365229 A2 [0003]

Claims (10)

Arrangement (10) for life-proof clamping connection of a plastic leaf spring (12) with a vehicle axle (18) or with a vehicle body part (18), - wherein the leaf spring (12) between a saddle element (14) and a plate element ( 16), - the saddle element (14) is connected to the vehicle axle (18) or the vehicle body part (18) and comprises four support regions (20a, b, c, d), each having an aperture, characterized in that - the plate element (16) on its side facing away from the leaf spring (12) comprises two transverse to the longitudinal extension of the leaf spring (12) extending guide grooves (22a, b), - in each guide groove (22a, b) of the plate element ( 16) in each case a clamping bracket (24a, b) extends, which with legs (26a, c, 26b, d) through two openings (28a, c, 28b, d) of the support portions (20a, b, c, d) of the saddle element (14) and further by elastic upsetting elements (30a, c; 30b, d), wherein d he end portions of the legs (26a, c; 26b, d) each have a screw thread (32a, c; 32b, d) for engagement in a mating thread (34a, c; 34b, d) of fixing means (36a, c, 36b, d), and by means of the fixing means (36a, c; 36b, d) are tension-loaded against the plate element (16) tension clamp (24a, b) and by the fixing means (36a, c, 36b, d) on the support areas (20a, b, c, d) adjoining compression elements (30a, c; 30b, d) pressure-loaded saddle element (14) has a clamping force between the plate element (16) and the saddle element (14) is constructed. Arrangement (10) according to Claim 1 characterized in that the mating thread (34a, c; 34b, d) is provided by a nut as fixing means (36a, c; 36b, d), the end portions of the legs (26a, c; Expanding elements (30a, c, 30b, d) extend beyond. Arrangement (10) according to one of the preceding claims, characterized in that the compression element (30a, c; 30b, d) is a helical compression spring, an evolute spring, an annular spring, a plate spring or a compression sleeve. Arrangement (10) according to Claim 1 characterized in that the upsetting member (30a, c; 30b, d) is a compression sleeve and the mating thread (34a, c; 34b, d) is provided by an end portion of the compression sleeve. Arrangement (10) according to one of the preceding claims, characterized in that the plate element (16) and / or the saddle element (14) consist of an inelastic material. Arrangement (10) according to one of the preceding claims, characterized in that the leaf spring (12) is a composite spring comprising a plastic. Arrangement (10) according to one of the preceding claims, characterized in that the compression element (30a, c; 30b, d) is a compression sleeve and whose ratio between the longitudinal extent and transverse extent is at least 2: 1. Arrangement (10) according to one of the preceding claims, characterized in that the clamping force is at least twice the force required for fixing the leaf spring (12) between the saddle element (14) and the plate element (16). Arrangement (10) according to Claim 8 in that the clamping force is 2.3 times to 3.6 times the minimum force required for fixing the leaf spring (12) between the saddle element (14) and in the plate element (16). Vehicle, in particular motor vehicle, comprising an arrangement (10) according to one of Claims 1 to 9 ,

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