DE202021103187U1 - Shock absorbers and methods of their manufacture - Google Patents

Abstract

A shock absorber (1) with a longitudinal axis (2), wherein the shock absorber (1) is configured such that it deforms between an uncompressed and a compressed state with a restoring force, and in the compressed state a smaller length in the direction of the longitudinal axis (2 ) has as in the uncompressed state, containing a base body (9) which functions as a stop damper, the base body (9) partially or completely consisting of a volume-compressible material; characterized in that the base body (9) further contains at least one secondary spring element (11, 11 ') which is integrated in the base body (9) and the secondary spring element (11, 11') between a first length in the uncompressed state and a second length is resilient in the compressed state and the second length is smaller than the first length and partially or completely consists of a compact second material, and that the base body (9) has a first spring rate and the secondary spring element (11, 11 ') a second Comprises spring rate, which is lower than the first spring rate, wherein the spring rate is defined as the ratio with which the respective spring element can be compressed relative to its uncompressed base state.

Description

The invention relates to a shock absorber, the shock absorber being designed in such a way that it deforms with a restoring force between an uncompressed and a compressed state.

Shock absorbers of the above type are well known. They are used, among other things, in the automotive industry to provide an additional spring element in shock absorber systems to prevent damage to the shock absorber in the event of excessive impacts.

The use of volume compressible materials such as cellular, in particular microcellular polyurethane foams, has gained in importance in recent years due to the advantageous properties of these materials. The manufacture of stop dampers from these materials is well known, including from the documents EP A 62 83 , EP A 36 994 , EP A 250 969 , DE A 195 48 770 and DE A 195 48 771 .

A number of users in the past have relied on rubber materials instead of volume compressible materials. In direct comparison with volume compressible materials, rubber or similar materials show a reduced compression, but at the same time also have a longer block length in the direction of the longitudinal axis. In some applications, an increased block length is a desired property that leads to a certain reluctance to use otherwise advantageous volume-compressible materials.

It was therefore the object of the invention to provide a shock absorber which meets the above requirements as far as possible. In particular, it was an object of the invention to find shock absorbers whose base body can be made from volume-compressible material, but at the same time enables a greater block length without impairing the advantageous damping and suspension properties of the volume-compressible material.

Surprisingly, this object can be achieved with a shock absorber according to claim 1. This shock absorber contains a base body in which a secondary spring element is included, wherein the secondary spring element can be compressed between a first length and a second length, the second length being shorter than the first Length and the secondary spring element consists partially or completely of a compact second material that is harder than that of the base body.

According to the invention, compact materials are understood to be non-cellular and insofar not or at least significantly less compressible in volume than cellular materials. The reduction in length in the direction of the longitudinal axis in the case of compact materials is generally at least partially compensated for by a radial expansion inwards and / or outwards.

One aspect of the invention is thus based on the knowledge that the integration of a secondary spring element with material properties that lead to reduced compression of the base body enables the block length of the shock absorber to be increased. On the deflection path into the compressed state, the secondary spring element withstands compression within the limits established by its spring power, which can be selected according to customer-specific requirements. At the same time, the base body, also known as the primary spring element, can be made of volume-compressible material so that a sensitive, i.e. "soft" initial resistance to deformation can be achieved. This means that in the bumper there is an ideal compromise between purely volume-compressible bumpers and purely compact bumpers: The deformation resistance is soft in the initial deformation stages, but increasingly progressive the greater the deformation, including an increased block length, which is due to the length of the secondary Spring element is limited.

By incorporating the secondary spring element in the base body, a single component achieves a progressive stiffening curve, which in the prior art is typically only achieved with additional support elements such as stiffening rings or the like. The present invention proposes a shock absorber with improved suspension properties and at the same time enables simplified manufacture and assembly on the vehicle suspension system. Another advantage of the embodiment according to the invention is the protection and shielding of the secondary spring element from environmental influences.

In a preferred embodiment, the base body encloses the secondary spring element at least partially and preferably completely. In particular, the secondary spring element is essentially enclosed in a cavity-free manner by the base body.

In a further preferred embodiment, the secondary spring element is designed such that it has a predetermined block length when it is in the compressed state.

In a further preferred embodiment, the base body, also referred to as the first spring element, has a first spring rate and the secondary spring element has a second spring rate which is lower than the first spring rate or equal to the first spring rate. The spring rate is the ratio with which the respective spring element can be compressed relative to its uncompressed basic state. For example, a spring element 100 mm long in its basic state and 30 mm in its fully compressed state (block length) would have a spring rate of 70%. A lower spring rate therefore indicates that the block length is increased relative to the uncompressed length.

Furthermore, the spring rate of the first spring element (without the second spring element) is preferably in the range of more than 65%, preferably 70% or more. Alternatively or additionally, the spring rate of the second spring element is in the range of 70% or less, preferably 65% or less.

• - Schraubenfeder, vorzugsweise helikal
• - Wellenfeder,
• - mehr als ein Ringelement, vorzugsweise Scheibenfedern oder Scheiben, die in Richtung der Längsachse voneinander getrennt sind, oder
• - unter Last verformbarer Käfig.

In a further preferred embodiment, the secondary spring element is selected from the list of the following spring elements:

• - helical spring, preferably helical
• - wave spring,
• - More than one ring element, preferably disc springs or washers, which are separated from one another in the direction of the longitudinal axis, or
• - cage deformable under load.

In a preferred embodiment, in particular when using one of the elements from the aforementioned list, the secondary spring element is more rigid in the radial direction than the primary spring element. The radial direction becomes any direction perpendicular to the direction of the longitudinal axis ( L. ) of the bumper understood. This enables a more homogeneous deformation of the primary spring element in the axial direction, since the radial expansion is restricted by the secondary spring element. This allows the bumper to be narrower around the longitudinal axis ( L. ) around, that is, it has a reduced width relative to its length. As a result, the surrounding parts, for example of the vehicle or vehicle suspension system, can also be dimensioned more advantageously.

Alternatively or additionally, the secondary spring element is preferably softer (as opposed to stiffer) in the longitudinal direction, ie parallel to the longitudinal axis ( L. ), as the primary spring element. This enables a preferred deformation behavior, ie initially soft compression and then progressively increasing stiffness and at the same time contributes to an increased block length.

In a further preferred embodiment, the material of the first element or of the base body is cellular, preferably microcellular, polyisocyanate polyaddition product.

The base body can consist of an elastomer here, but it can also consist of a large number of elastomers which are present in layers, in the form of a shell or in another form or also in mixed forms. The polyisocyanate polyadducts are preferably produced on the basis of microcellular polyurethane elastomers, on the basis of thermoplastic polyurethane or from combinations of these two materials, which can optionally include polyurea structures.

In a preferred embodiment, microcellular polyurethane elastomers meet at least one of the following parameters: a density according to DIN 53420 of 200 kg / m ³ to 1100 kg / m ³ , preferably 300 kg / m ³ to 800 kg / m ³ , a tensile strength according to DIN 53571 of 2 N / mm ² , preferably 2 N / mm ² to 8 N / mm ² , an elongation according to DIN 53571 of more than 300%, preferably 300% to 700%, and a tear strength according to DIN 53515 of preferably 8 N / mm to 25 N / mm, or combinations of these parameters, very particularly preferably all of these parameters or their preferences are met.

The elastomers are preferably microcellular elastomers based on polyisocyanate polyaddition products, preferably with cells with a diameter of 0.01 mm to 0.5 mm, particularly preferably 0.01 to 0.15 mm.

Elastomers based on polyisocyanate polyadducts and their preparation are well known and are described in large numbers, e.g. Am EP A 62 835 , EP A 36 994 , EP A 250 969 , DE A 195 48 770 and DE A 195 48 771 .

The production usually takes place by reaction of isocyanates n.V. with compounds that react to isocyanates.

The elastomers based on cellular polyisocyanate polyadducts are usually produced in a form in which the reactive starting components react with one another. Suitable shapes here are usually customary shapes, for example metal shapes, which, due to their shape, ensure the three-dimensional shape of the spring element according to the invention. In one embodiment, the contour elements are integrated directly into the casting mold; in a further embodiment, they are subsequently integrated into the preferably concentric base body. In a preferred embodiment, the concentric spring element is closed For this purpose cooled until it solidifies, preferably with liquid nitrogen, and processed in this state.

1. a) Isocyanat,
2. b) Verbindungen, die auf Isocyanate reaktiv sind,
3. c) Wasser und gegebenenfalls
4. d) Katalysatoren,
5. e) Treibmittel und/oder
6. f) Hilfsstoffe und/oder zusätzliche Stoffe, z. B. Polysiloxane und/oder Fettsäuresulfonate.

The polyisocyanate polyadducts can be prepared by generally known processes, for example using the following starting materials, which are used in one or two-stage processes:

1. a) isocyanate,
2. b) compounds that are reactive to isocyanates,
3. c) water and optionally
4. d) catalysts,
5. e) propellant and / or
6. f) auxiliary materials and / or additional substances, e.g. B. polysiloxanes and / or fatty acid sulfonates.

The surface temperature of the inner wall of the mold is usually 40 ° C to 95 ° C, preferably 50 ° C to 90 ° C. The molded parts are advantageously produced at an NCO / OH ratio of 0.85 to 1.20, the heated starting components being mixed and placed in a heated, preferably tightly fitting mold in an amount corresponding to the desired molded part density. The molded parts are preferably cured for 5 minutes to 60 minutes and can then be removed from the mold. The amount of the reaction mixture introduced into the mold is preferably dimensioned in such a way that the moldings obtained have the density already shown. The starting components are usually introduced into the mold at a temperature of from 15 ° C. to 120 ° C., preferably from 30 ° C. to 110 ° C. The degrees of compression for the production of the molded bodies are between 1.1 and 8, preferably between 2 and 6. The cellular polyisocyanate polyadducts are expediently made according to the “one shot” process with the aid of high pressure technology, low pressure technology or, in particular, reaction injection molding technology (RIM) in open or preferably closed molds made. The reaction takes place in particular by compression in a closed mold. Reaction injection molding technology is used, for example, by H. Piechota and H. Röhr in "Integralschaumstoffe", Carl Hanser-Verlag, Munich, Vienna 1975 described; DJ Prepelka and JL Wharton in Journal of Cellular Plastics, March / April 1975, pages 87 to 98 and U. Knipp in Journal of Cellular Plastics, March / April 1973 , Pages 76-84.

In a further preferred embodiment, the material of the second spring element is selected from one of the following materials: an elastomer, a metal, preferably steel, a steel alloy, aluminum or an aluminum alloy, a fiber composite material or a combination of several or all of the aforementioned materials. When using metal, a primer is preferably applied between the first and second spring elements in order to improve the adhesion between the two spring elements and to increase the service life of the shock absorbers.

• - ein Young-Modul von 225 MPa oder mehr, weiter vorzugsweise 750 MPa oder mehr, oder vorzugsweise ein Young-Modul von 2200 MPa oder niedriger, oder besonders bevorzugt ein Young-Modul in einem Bereich von 800 MPa bis 2200 MPa;
• - eine Härte von 40D oder mehr, vorzugsweise 60D oder mehr, oder vorzugsweise eine Uferhärte von 90D oder niedriger, oder besonders bevorzugt im Bereich von 60D bis 90D;
• - eine Zugfestigkeit von 40 MPa oder mehr, oder vorzugsweise eine Zugfestigkeit von 70 MPa oder niedriger oder besonders bevorzugt eine Zugfestigkeit in einem Bereich von 40 MPa bis 70 MPa;
• - eine Dichte von 1,10 g/cm3 oder höher, oder vorzugsweise eine Dichte von 1,45 g/cm3 oder niedriger, oder besonders bevorzugt in einem Bereich von 1,10 bis 1,45 g/cm3.

The material of the second shock absorber preferably has one, more, or all of the following properties:

• a Young's modulus of 225 MPa or more, more preferably 750 MPa or more, or preferably a Young's modulus of 2200 MPa or lower, or particularly preferably a Young's modulus in a range from 800 MPa to 2200 MPa;
• a hardness of 40D or more, preferably 60D or more, or preferably a shore hardness of 90D or lower, or more preferably in the range of 60D to 90D;
• a tensile strength of 40 MPa or more, or preferably a tensile strength of 70 MPa or lower, or particularly preferably a tensile strength in a range from 40 MPa to 70 MPa;
• a density of 1.10 g / cm3 or higher, or preferably a density of 1.45 g / cm3 or lower, or particularly preferably in a range from 1.10 to 1.45 g / cm3.

The secondary spring element preferably has an initial rigidity in the longitudinal direction in a range of 60 N / mm or less, preferably 20 N / mm or less, more preferably 10 N / mm or less.

The secondary spring element preferably has an initial rigidity in the longitudinal direction in a range of 3 N / mm or more, preferably 5 N / mm or more.

The Young's modulus is preferably after DIN EN ISO 527 certainly. The hardness is preferably after DIN ISO 7619-1 (3S) determined. The tensile strength is preferably after DIN 53504-S2 certainly.

• - Polyurethan auf Polyetherbasis,
• - Polyurethan auf Polyesterbasis,
• - thermoplastisches Polyurethan auf Polyetherbasis,
• - thermoplastisches Polyurethan auf Polyesterbasis,
• - halbkristalliner Thermoplast
• - Faserverbundwerkstoff mit thermoplastischem Polyurethan als Matrixmaterial, das thermoplastische Material vorzugsweise auf Polyesterbasis ist.

Vorteilhafterweise können diese Materialien chemisch an volumenkomprimierbare Materialien wie das oben genannte zelluläre Polyisocyanat-Polyadditionsprodukt gebunden werden.In particularly preferred embodiments, the material of the second spring element consists or consists of an elastomer, and this elastomer is selected from the following list:

• - polyether-based polyurethane,
• - polyester-based polyurethane,
• - thermoplastic polyurethane based on polyether,
• - polyester-based thermoplastic polyurethane,
• - semi-crystalline thermoplastic
• - Fiber composite material with thermoplastic polyurethane as the matrix material, the thermoplastic material is preferably based on polyester.

Advantageously, these materials can be chemically bonded to volume compressible materials such as the cellular polyisocyanate polyadduct mentioned above.

A preferred polyurethane based on polyether or polyester would be, for example, Elasturan® commercially available from BASF Polyurethanes GmbH, Lemfoerde, Germany.
A preferred TPU based on polyether would be, for example, Elastollane®, 12 series, such as. B. 1283 D 11 U 000 or 1278 11 U 000, commercially available from BASF Polyurethanes GmbH, Lemfoerde, Germany. A preferred polyester fiber composite would be, for example, Elastollan® of the R series such as R2000, which is available from BASF Polyurethanes GmbH, Lemfoerde, Germany.
A preferred polyester-based TPU would be, for example, Ellastolan® C74D50, which is available from BASF Polyurethanes GmbH, Lemfoerde, Germany.
A preferred semi-crystalline thermoplastic would be, for example, polyoxymethylene (POM) or polyamide such as PA 6.6.

Another subject of the invention is the treatment of the molds in order to obtain longer standing times. If molding tools are filled several times with plastics, preferably polyurethanes, more preferably thermoplastic polyurethane, microcellular polyurethane, flexible polyurethane foam, rigid polyurethane foam, or microcellular polyurethane, which particularly preferably contains polyurea groups, residues of this material remain on the molded body and are removed from time to time have to.

In a preferred embodiment, if casting residues have built up there, the molds are therefore subjected to cleaning. We prefer cleaning by blasting fine-grained material with high pressure onto the soiled surfaces of the molds. This is preferably done at pressures between 4 and 8 bar, preferably between 5 and 7 bar, particularly preferably at 6 bar. The air requirement is between 400 - 1500 l / min.
In principle, many materials are suitable for cleaning the molds. Examples of cleaning materials include sand, silicon compounds, metal bodies and plastics. It is important that the cleaning materials on the one hand are sufficiently hard to remove the contamination from the molds, but at the same time they must not be too hard in order not to remove the mold too much. The deposits come from the release agent used and the plastic used for the molded part. Plastics are preferably used for cleaning the molds. Preferred plastics are acrylates or aminoplasts, in particular melamines, polyureas and urea-formaldehyde resins. Commercially available products from Wiwox GmbH (Ekrath, Germany) which are available under the trade name Wiwox® KS are preferred, among others.
It has also been shown to be advantageous that cleaning agents, in particular those plastics which contain urea groups, are used in a mixture with high-melting polishing agents. To do this, the cleaning agent is mixed with the polishing agent. Suitable additives can be added to the mixture.
Mixing the detergent and polishing agent when cleaning has many advantages. After the separation, a thin layer remains on the casting mold, which leads to reduced deposits in the further casting process, ie the residue from the cleaning process already has separating properties again. These can be further improved by applying the same or other release agents. At the same time, the amount of the release agent applied further can be reduced.
Overall, this leads to a simplification of the casting process, which creates savings potential. The applied polishing agent already reduces buildup during the first casting cycles,
even if further release agent has not yet been reliably applied to the entire surface of the mold. By using the polish, the amount of release agent used can be reduced, as the polish prevents contact between the mold surface and the casting material. Due to the low level of adhesion between polish deposits, subsequent cleaning of the molds is often easier and quicker. The deposit layer often flakes off over a large area during mechanical cleaning processes.
Cleaning and polishing agents are preferably in the form of granules or powder, preferably with a diameter of the individual granule particles in the range from 0.05 mm to 4 mm, preferably 0.4 mm to 1.2 mm.
The polishing agent is preferably selected from the group consisting of polyethylene, wax and paraffin, or is a mixture thereof. In a preferred embodiment the wax is canauba wax. Polyethylene is particularly preferred. The polishing agent is preferably used in such a way that its melting point is above the mold temperature.
The polyethylene used as a polishing agent preferably has a weakly branched one, if possible linear structure. The polyethylene preferably has a molecular weight between 0.5 × 10 ³ g / mol and 10 × 10 ³ g / mol, preferably between 0.5 × 10 ³ g / mol and 5 × 10 ³ g / mol, more preferably between 0, 5 × 10 ³ g / mol and 3 × 10 ³ g / mol, more preferably between 0.6 × 10 ³ g / mol and 2 × 10 ³ g / mol and particularly preferably between 0.7 × 10 ³ g / mol and 1.2 x 10 ³ g / mole. A suitable process is the production of the polyethylene by the Fischer Tropsch synthesis process. Other suitable methods are, for example, the Ziegler and Phillips synthesis methods. These processes preferentially produce linear polyethylenes that exhibit better polishing properties.
The polyethylene preferably has no branch points. No branching point means that the production conditions are selected in such a way that idealized linear polyethylenes are produced. It cannot be ruled out that there may be isolated branching points in practice.
The polyethylene preferably has a melting point above the mold temperature used for the casting process, so that the coating preferably remains solid during the casting process, so that it can be used for several casting processes. The melting point of the polyethylene is preferably between 40.degree. C. and 150.degree. C., more preferably between 50.degree. C. and 140.degree. C., and the polyethylene particularly preferably has a melting point between 50.degree. C. and 120.degree.
A mixture consisting of 5-20% by weight of a polyethylene, preferably as described above, preferably a Fisher-Tropsch hard wax from Sasol Ltd., particularly preferably of the H1N6, H5, or Sasobit type, and 80 to 95% by weight of is preferred a cleaning granulate that adds up to 100% by weight with the polyethylene. The cleaning granules from Wiwox® GmbH are preferred, and the cleaning granules of the KS type are preferred.
The mixture described above is well suited for all casting tools used in the casting of plastics, preferably polyurethanes, particularly preferably microcellular polyurethane. It is particularly suitable for casting tools made of metal, preferably steel or aluminum alloys.
In principle, the mixture is suitable for cleaning and as a coating in all primary molding processes in plastics processing, particularly good for polyurethanes, especially those based on diphenylmethane diisocyanate (MDI), and the mixture for molded parts made of microcellular polyurethane, preferably based on MDI suitable.

In a further preferred embodiment, the secondary spring element is a wave spring, as mentioned above, and consists of a first end section and opposite the second end section and a series of juxtaposed undulating rings between the two end sections, each ring being undulating in the direction of the longitudinal axis. The wavy rings preferably extend circumferentially around the secondary spring element and preferably have a meandering shape between the parts which are closer to the first end section and parts which are closer to the second end section. In the sections which are closest to a respective end part, each corrugated ring is preferably connected either to one of the end portions or to an adjacent corrugated ring.

Furthermore, the wave spring is preferably contained in the base body in such a way that the end sections and the rings merge seamlessly into one another.

In a preferred embodiment, the secondary spring element consists of a multiplicity of merging sections, wherein in each merging section one of the rings either fuses to one of the end sections or to one of the adjoining rings. This is to be understood in such a way that, under a plurality of wave-shaped rings, the rings which are closest to the respective end sections merge into their adjacent end parts, while the intermediate rings merge into one another.

In a further preferred embodiment, the merging sections for adjacent rings are evenly distributed over the secondary spring element. Furthermore, the joining sections, in which a ring fuses to form an end part, are also preferably formed uniformly over the secondary spring element.

In a further preferred embodiment, for all merging sections or at least the merging sections between adjacent rings or adjacent merging sections at an angle around the longitudinal axis, this angle is preferably in a range between 15 ° and 165 °, more preferably between 60 ° ° and 120 ° and particularly preferably between 75 ° and 105 °.

Adjacent merging sections are preferably at an angle of 90 ° around the longitudinal axis ( L. ) separated from another.

The aforementioned equidistant distribution of adjacent merging sections achieves a higher uniformity of the elastic deformation, in particular with regard to the lateral bending of the secondary spring element and of the shock absorber in general. This has a positive effect on the deformation properties of the bumper as a whole.

In a further preferred embodiment, each joining section consists of a clamped-together part which extends in the longitudinal direction. The clamped parts in the joining sections contribute to a more flexible deformation of the secondary spring element.

In a further preferred embodiment, at least one of the end sections of the secondary spring element comprises a plurality of inwardly expanding projections. The projections are preferably separated from one another and create recesses between adjacent projections. The projections are preferably distributed uniformly along the circumference of the secondary spring element.

In a further preferred embodiment, at least one of the end sections of the secondary spring element comprises a plurality of outwardly directed projections. In preferred embodiments, the outwardly oriented projections are also formed similarly to the inwardly oriented projections, namely distributed (preferably equidistantly) along the circumference of the end section.

The projections enable a secondary spring element to be better embedded in the primary spring element if they are filled with material of the primary spring element, also referred to as the base body.

In a further preferred embodiment, at least one of the end sections of the secondary spring element comprises a plurality of material passages which extend in the direction of the longitudinal axis ( L. ) extend. The material passages can be filled with material of the primary spring element, ie the base body, or left empty. If the passages are left empty, the material passages function as air outlet holes in the later movement, which facilitate the compression of the shock absorber.

The invention has been generally described herein in a first aspect in relation to shock absorption. In a preferred embodiment, the invention also relates to a method for reducing a shock absorber for use in a vehicle suspension system, in particular a shock absorber according to one of the preferred embodiments described above.

• - Bereitstellung einer Gießform mit einer inneren Form, die der vorgegebenen äußeren Form der herzustellenden Grundkörpers entspricht;
• - Positionieren des sekundären Federelements innerhalb der Form, wobei das aus einem kompakten Material bestehende sekundäre Federelement entlang der Achse (I) zwischen einer ersten Länge im unkomprimierten Zustand und einer zweiten Länge im komprimierten Zustand verformbar ist, und
• - Zugabe eines Reaktionsgemisches, um den Grundkörper in der Form zu gießen, wobei dieses Reaktionsgemisch so gewählt ist, dass es ein volumenkompressibles Material ausbilden kann,und
• - die Reaktionsbedingungen innerhalb der Form so beschaffen sind, dass sich das Reaktionsgemisch ausdehnt und ein volumenkomprimierbares Material bildet, das die äußere Form des Grundkörpers annimmt und das sekundäre Federelement in sich integriert.

The invention achieves the object set out above with the following method:

• - Provision of a casting mold with an inner shape which corresponds to the predetermined outer shape of the base body to be produced;
• - Positioning the secondary spring element within the mold, the secondary spring element made of a compact material being deformable along the axis (I) between a first length in the uncompressed state and a second length in the compressed state, and
• - Addition of a reaction mixture in order to cast the base body in the mold, this reaction mixture being selected so that it can form a volume-compressible material, and
• - The reaction conditions within the mold are such that the reaction mixture expands and forms a volume-compressible material that adopts the outer shape of the base body and integrates the secondary spring element.

The process of providing the reaction mixture and the respective reaction conditions for producing the volume-compressible material is generally known in the prior art.

Accordingly, the reaction mixture and the reaction conditions required for the particular reaction mixture can and will be selected from the commercially available methods and the publicly available literature. The advantage of this method is that the secondary spring element can be inserted into the mold with little effort. The process for creating the basic body remains unchanged. After the production of the base body, no additional production or installation measures have to be carried out, since the secondary spring element is then already integrated into the base body.

A further aspect of the invention with which the above-mentioned object is achieved is the use of a spring element, which consists partially or completely of a compact material as a secondary spring element within a base body of a shock absorber, the secondary spring element being integrated into the base body and the base body consisting of a volume compressible material, in particular one which is described in one of the preferred embodiments described above.

The preferred embodiments of the shock absorber under the first aspect of the invention are at the same time preferred embodiments of the second aspects and vice versa. Likewise, the advantages and benefits described above are related on the bumper at the same time advantages and advantages of the method according to the invention and the inventive use and vice versa, so that reference is made to the above statements in order to avoid unnecessary repetition.

In a fourth aspect, the invention relates to a spring element for use in a suspension system, in particular in a vehicle suspension system, the spring element being resilient between a first length in the uncompressed state and a second length in the compressed state, the second length being smaller than the first length is, and the spring element consists partially or completely of a compact material.

The secondary spring element described above as an integral part of the shock absorber according to the invention is preferably suitable to be integrated according to one of the aforementioned aspects in a base body that functions as a primary spring element at a first spring rate, and the spring element is a secondary spring element that has a second spring rate which is lower than the first spring rate, wherein the spring rate is defined as the ratio with which the respective spring element can be relatively compressed.

However, the spring element of this aspect also represents an aspect according to the invention on its own, the spring element being configured according to the secondary spring element of the secondary spring element of the bumper defined in one of the preferred embodiments described above. Preferred embodiments of the so-called secondary spring element of the preceding aspects are at the same time preferred embodiments of this aspect and vice versa. Reference is made to the description herein above and to the following description and claims.

In a preferred embodiment, the spring element is configured such that it has a predetermined block length when it is in the compressed state.

The spring rate of the spring element is in the range of 70% or less, preferably 65% or less.

In a further preferred embodiment, the spring element is a wave spring.

In a further preferred embodiment, the spring element consists or consists of: an elastomer, a fiber composite material or a combination of several or all of the aforementioned materials.

• - ein Young-Modul von 225 MPa oder mehr, weiter vorzugsweise 750 MPa oder mehr, oder vorzugsweise ein Young-Modul von 2200 MPa oder niedriger, oder besonders bevorzugt ein Young-Modul in einem Bereich von 800 MPa bis 2200 MPa;
• - eine Härte von 40D oder mehr, vorzugsweise 60D oder mehr, oder vorzugsweise eine Uferhärte von 90D oder niedriger, oder besonders bevorzugt im Bereich von 60D bis 90D;
• - eine Zugfestigkeit von 40 MPa oder mehr, oder vorzugsweise eine Zugfestigkeit von 70 MPa oder niedriger oder besonders bevorzugt eine Zugfestigkeit in einem Bereich von 40 MPa bis 70 MPa;
• - eine Dichte von 1,10 g/cm3 oder höher, oder vorzugsweise eine Dichte von 1,45 g/cm3 oder niedriger, oder besonders bevorzugt in einem Bereich von 1,10 bis 1,45 g/cm3.

The material of the spring element preferably has one, several or all of the following properties:

• a Young's modulus of 225 MPa or more, more preferably 750 MPa or more, or preferably a Young's modulus of 2200 MPa or lower, or particularly preferably a Young's modulus in a range from 800 MPa to 2200 MPa;
• a hardness of 40D or more, preferably 60D or more, or preferably a shore hardness of 90D or lower, or more preferably in the range of 60D to 90D;
• a tensile strength of 40 MPa or more, or preferably a tensile strength of 70 MPa or lower, or particularly preferably a tensile strength in a range from 40 MPa to 70 MPa;
• a density of 1.10 g / cm3 or higher, or preferably a density of 1.45 g / cm3 or lower, or particularly preferably in a range from 1.10 to 1.45 g / cm3.

The shock absorber preferably has an initial stiffness in the longitudinal direction of the axis ( L. ) in a range of 60 N / mm or less, preferably 20 N / mm or less, more preferably 10 N / mm or less, or the secondary spring element has an initial stiffness in the longitudinal direction in a range of 3 N / mm or, preferably 5 N / mm or more, or the secondary spring element has an initial rigidity in the longitudinal direction in a range from 3 N / mm to 60 N / mm, preferably 5 N / mm to 20 N / mm, more preferably in a range from 6 N / mm to 15 N / mm.

The Young's modulus is preferably after DIN EN ISO 527 certainly. The hardness is preferably after DIN ISO 7619-1 (3S) certainly. The tensile strength is preferably after DIN 53504-S2 certainly.

• - Polyurethan auf Polyetherbasis,
• - Polyurethan auf Polyesterbasis,
• - thermoplastisches Polyurethan auf Polyetherbasis,
• - thermoplastisches Polyurethan auf Polyesterbasis,
• - halbkristalliner Thermoplast
• - Faserverbundwerkstoff mit thermoplastischem Polyurethan als Matrixmaterial, das thermoplastische Material vorzugsweise auf Polyesterbasis ist.

Vorteilhafterweise können diese Materialien chemisch an volumenkomprimierbare Materialien wie das oben genannte zelluläre Polyisocyanat-Polyadditionsprodukt gebunden werden.In particularly preferred embodiments, the secondary spring element consists of an elastomer, and the elastomer is selected from the following list:

• - polyether-based polyurethane,
• - polyester-based polyurethane,
• - thermoplastic polyurethane based on polyether,
• - thermoplastic polyurethane based on polyester,
• - semi-crystalline thermoplastic
• - Fiber composite material with thermoplastic polyurethane as matrix material, the thermoplastic material is preferably polyester-based.

Advantageously, these materials can be chemically bonded to volume compressible materials such as the cellular polyisocyanate polyadduct mentioned above.

A preferred polyurethane based on polyether or polyester would be, for example, Elasturan® commercially available from BASF Polyurethanes GmbH, Lemfoerde, Germany.
A preferred polyether-based TPU would be, for example, Elastollan®, line 12, such as B. 1282 D 11 U 000 or 1278 11 U 000, commercially available from BASF Polyurethanes GmbH, Lemfoerde, Germany. A preferred polyester fiber composite would be, for example, Elastollan® line R such as R2000, which is available from BASF Polyurethanes GmbH, Lemfoerde, Germany.
A preferred polyester-based TPU would be, for example, Ellastolan® C74D50, which is available from BASF Polyurethanes GmbH, Lemfoerde, Germany.

A preferred semi-crystalline thermoplastic would be, for example, polyoxymethylene (POM) or polyamide such as PA 6.6.

In a further preferred embodiment, the secondary spring element is a wave spring, as mentioned above, and consists of a first end section and opposite the second end and a series of juxtaposed undulating rings between the two end sections, each ring being undulating in the direction of the longitudinal axis. The wavy rings ie extend circumferentially around the spring element and have a meandering shape between the parts which are closer to the first end portions and the parts which are closer to the second end portion. In the sections which are closest to a respective end part, each corrugated ring is preferably coupled either to one of the end portions or to an adjacent corrugated ring.
Furthermore, the wave spring is preferably integrated in such a way that the end sections and the rings merge seamlessly into one another.
In a preferred embodiment, the spring element consists of a plurality of merging sections, wherein in each merging section one of the rings either fuses to one of the end sections or to one of the adjoining rings. It is to be understood that among a plurality of wave-shaped rings, the rings which are closest to the respective end sections merge into their adjacent end part, while the intermediate rings merge into one another.
In a further preferred embodiment, the merging sections for adjacent rings are formed uniformly over the secondary spring element. Furthermore, the joining sections, in which a ring fuses to form an end part, are also preferably formed uniformly over the secondary spring element.
In a further preferred embodiment, for all merging sections or at least the merging sections between adjacent rings to or adjacent merging sections at an angle about the longitudinal axis, this angle is preferably in a range between 15 ° and 165 °, more preferably between 60 ° and 120 ° and particularly preferably between 75 ° and 105 °.

Adjacent merging sections are preferably separated from one another at an angle of 90 ° around the longitudinal axis.

The aforementioned equidistant distribution of adjacent merging sections achieves improved uniformity of the elastic deformation, in particular for the lateral bending of the spring element.

In a further preferred embodiment, each joining section consists of a clamped part which extends in the longitudinal direction. The clamped together parts in the joining sections contribute to a more flexible deformation of the spring element.

In a further preferred embodiment, at least one of the end sections of the spring element comprises a plurality of inwardly expanding projections. The projections are preferably separated from one another and create recesses between adjacent projections. The projections are preferably distributed uniformly along the circumference of the secondary spring element.

In a further preferred embodiment, at least one of the end sections of the spring element comprises a plurality of outwardly expanding projections. In preferred embodiments, the outwardly expanding projections are also formed similarly to the inwardly expanding projections, namely distributed (preferably equidistantly) along the circumference of the end section.

The projections enable a secondary spring element to be better embedded in the primary spring element if they are filled with material from the base body.

In a further preferred embodiment, at least one of the end sections of the spring element comprises a multiplicity of material passages which extend in the direction of the longitudinal axis. The material passages can be inserted with spring material if they are embedded in a primary spring element, ie a base-based body, or they can be left empty. When empty, the material passages function as air outlet holes that facilitate the compression of the spring element.

• zeigt eine schematische dreidimensionale Ansicht eines Stoßfängers gemäß einer bevorzugten Ausführungsform,
• zeigt verschiedene Seitenansichten und Querschnittsansichten des Stoßfängers von ,
• zeigt eine schematische dreidimensionale Ansicht eines sekundären Federteils für die Stoßstange der und ,
• zeigt verschiedene Seiten- und Querschnittsansichten des Federelements von ,
• zeigt eine schematische dreidimensionale Ansicht eines alternativen sekundären Federteils für die Stoßstange der und und
• zeigt verschiedene Seiten- und Querschnittsansichten des Federelements in .

The invention is described in more detail below with reference to the accompanying drawings of a preferred embodiment. Here in:

• shows a schematic three-dimensional view of a bumper according to a preferred embodiment,
• FIG. 13 shows various side and cross-sectional views of the bumper of FIG ,
• FIG. 13 shows a schematic three-dimensional view of a secondary spring part for the bumper of FIG and ,
• FIG. 13 shows various side and cross-sectional views of the spring element of FIG ,
• FIG. 13 shows a schematic three-dimensional view of an alternative secondary spring part for the bumper of FIG and and
• FIG. 13 shows various side and cross-sectional views of the spring element in FIG .

shows a typical exterior view of a bumper 1 according to a preferred embodiment of the invention. The bumper 1 consists of a first end face 3 and an opposite end face 5 that from the first final phase 3 along a longitudinal axis L. away. The bumper 1 has a substantially cylindrical shape and consists of a series of lateral annular recesses 7th configured to facilitate axial compression, ie compression in the direction of the longitudinal axis. In becomes the bumper 1 shown in their uncompressed base state. The cylindrical shape is common in automotive applications. It is to be understood, however, that other shapes are possible within the scope of the invention, such as, for example, polygonal shapes or (partially completely) oval shapes.

During operation, the bumper deforms in the event of external impacts from the vehicle suspension system in such a way that the two end faces meet 3 , 5 approach each other. The resistance that the bumper 1 builds up against this deformation, characterizes the overall deformation behavior of the bumper 1 .

The bumper 1 consists of a basic body 9 , which consists of a volume-compressible material, for example microcellular polyurethane foam, as it is commercially available as Cellasto® from BASF Polyurethanes GmbH, Lemfoerde, Germany.

The volume-compressible material of the base body has a favorable deformation behavior, since it is easily and elastically deformed. At the same time, the volume-compressible material has a very short block length in the direction of the longitudinal axis, if you consider it purely by itself.

The interior shape of the shock absorber of the 1 is in the until that together form, shown in more detail.

Like in particular the - show which are cross-sectional views, and as in indicated is the basic body 9 not the only part of the shock absorber 1 . Rather, the main body functions 9 as the primary spring element, and the shock absorber further consists of a secondary spring element 11 that is in the basic body 9 is integrated, preferably from the base body 9 around the secondary spring element 11 enveloped. The secondary spring element 11 consists preferably of a compact, non-volume-compressible material that differs from the material of the base body 9 differs. The secondary spring element is between the uncompressed basic state, shown in FIG - , and a compressed state, wherein the spring element in the compressed state in the direction of the longitudinal axis L. is shorter than in the uncompressed base state. The block length of the secondary spring element per se is, due to the compact nature of its material, significantly greater than it would be if it were made from a volume-compressible material.

Thus, the secondary spring element represents 11 the shock absorber 1 a specified minimum block length is available.

At the same time is the secondary spring element 11 resilient, so that it is together with the base body 9 deformed.

Due to the complete integration into the material of the base body 9 the secondary spring element is completely protected from environmental influences, in particular particles, liquids and radiation.

In particular, the cross-sectional views of FIG - that the secondary spring element 11 completely in the body 9 is encapsulated. According to these cross-sectional views, the material strength is the - not over the entire circumference of the secondary spring element 11 identical. The complete support structure of the secondary spring element according to the preferred embodiment is shown in FIG shown in more detail.

Like in particular from becomes clear, becomes the secondary spring element 11 designed as a resiliently deformable cage. The secondary spring element 11 consists of a first end section 13th and an opposite second end portion 15th . When cast in the shock absorber, the first end portion becomes 13th towards the first end section 3 of the shock absorber 1 positioned while the second end portion 15th towards the second end section 5 of the shock absorber 1 is directed.

Between the two end sections 13th , 15th is the secondary spring element 11 from a variety of angled spring leaves 21a , b , c each of which is at an angle with respect to the first and second end portions 13th , 15th is aligned.

shows the secondary spring element 11 in its uncompressed basic state.

The spring leaves pivot under axial load 21a , b , c in relation to the end sections 13th , 15th off so that the angle between the spring leaves 21a , b , c and the respective end sections 13th , 15th or the respective adjacent spring travel decreases. If between the end sections 13th , 15th and the spring leaves 21a , b , c If no material were available, the spring leaves would 21a , b , c Pivot until they abut against the respective adjacent spring travel or on the end part, which define the minimum block length of the secondary spring element. If in the basic body 9 of the shock absorber 1 shaped as in the and shown is the secondary spring element 11 in most cases its theoretically possible minimum block length due to the material of the base body 9 between the spring leaves 21a , b , c and end sections 13th respectively. 15th not reach.

How out results are the spring leaves 21a , b , c configured to have a first material thickness M1 in the direction of the longitudinal axis ( L. ) and a second material thickness M2 in the radial direction with respect to the longitudinal axis ( L. ) exhibit. The second material thickness M2 is greater than the first material thickness M1 . Combined with this, this has the effect that the secondary spring element 11 is very easily deformable in the axial direction, which leads to a low spring rate, while at the same time a very small transverse expansion is possible during the compression, which in turn for the compression stability in the radial direction of the bumper 1 overall is beneficial.

A set of first spring leaves is preferred 21a integral to the first end section 13th formed while a second set of spring leaves 21c with the second end portion 15th is integrally formed.

The secondary spring element 11 also consists of a number of intermediate spring leaves 21b each integral with adjacent spring leaves 21a , b , c are trained.

To achieve better axial compression, ie in the direction of the longitudinal axis L. To enable comprises the secondary spring element 11 preferably connections 25th reduced material thickness to avoid the pivoting movement of the spring leaves 21a , b , c to facilitate.

To improve the passage of the molding material of the base body 9 by the volume of the secondary spring element 11 to enable comprises the first end portion 13th preferably a plurality of material passages 27 , in which the volume-defining material of the base body 9 can expand during molding.

The second end section also preferably comprises 15th a variety of material passages 29 that makes it the volume-compressible first material of the base body 9 allow the second end portion 19th to go through.

the that together form, show a side view ( ) and a cross-sectional view ( of the secondary spring element 11 . As in and can be seen, in particular, are some of the intermediate spring leaves 21b through a ridge 23 integrated to improve the transverse stability again.

That in the - The illustrated secondary spring element offers converging sections, which have two types of articulation between the end sections 13th , 15th and the spring leaves 21a , b , c are shaped. In particular the joints 25th between the adjacent spring leaves 21a , b have a fairly articulated clamp to allow easy flexing while at the same time extending over a substantial angular range about the longitudinal axis L. extend as in is best seen. The joints 25th are arranged opposite one another, with their midpoints lying in a common plane, which is also the longitudinal axis L. includes.

The midpoints of the ridges 23 are in a second plane perpendicular to this plane mentioned above. Ribs 23 are also quite thin and ensure the stability of the secondary spring element 11 as far as the spring leaves 21b , c can escape radially outwards or inwards during compression.

the and show an alternative embodiment of a secondary spring element 11 ' which has many structural features and qualities with the one in the - spring element shown as an example 11 having. Identical features have been identified with identical reference symbols, and reference is made to the description herein in order to avoid unnecessary repetition.

The secondary spring element 11 ' differs from the secondary spring element 11 the - in that the first end portion 13 ' a plurality of inwardly extending protrusions 14th includes, which are formed in the present embodiment as radial ribs that extend to the longitudinal axis L. expands. These protrusions 14th serve as additional structural reinforcements. Between the adjacent protrusions 14th recesses 16 are formed, which can be filled with material, around the secondary spring element 11 ' to anchor further in the primary spring element, ie the base body.

It also includes the secondary spring element 11 ' also in the first section 13 ' a plurality of outwardly expanding protrusions 18th . The protrusions 18th are separated from one another by recesses 20, which act as air outlet cavities or can also be filled with material from the primary spring element. Likewise, the inner recesses 16 between adjacent projections 14th act as air exit cavities when left empty. The material passages 25th , 27 the secondary spring elements 11 , 11 ' can also be filled with material from the base body or left blank as above.

The secondary spring element 11 ' differs from the secondary spring element 11 in the structure of the elastic elements themselves: while the secondary spring element 11 spring leaves positioned opposite 21 a , b , c includes, includes the secondary spring element 11 ' a more refined version of it in the form of a multitude of undulating rings that extend around the longitudinal axis L. expand circumferentially and, compared to the order, more evenly along the secondary spring element 11 .

Every ring 22nd is integral with the secondary spring element 11 ' educated. The Rings 22nd either merge with one of the end sections 13 ' , 15th in a merging section 28a or with an adjacent ring 22nd in a merging section 28b . While also the ridges 23 and the joints 25th of the secondary spring element 11 of the first embodiment in principle, the mechanical behavior of these elements is not identical to one another.

In contrast, all have merging sections 28b essentially the same deformation behavior, and all merging sections 28a also have the same deformation behavior.

The ones in the , The setting shown provides that each merging section 28a , b next to an adjacent merge section 28b at an angle of 90 degrees around the longitudinal axis ( L. ) is arranged so that the uniformity of the deformation compared to the embodiment of the - is improved.

The second merging sections 28b and to some extent the first merging sections as well 28a include a clamping section 30th that extends in the direction of the longitudinal axis L. extends to ensure greater flexibility and so the risk of mechanical failure of the secondary spring element 11 to reduce.

In the description of the illustrations above, the illustrations described are the secondary spring elements 11 , 11 ' in connection with the shock absorber of one aspect of the invention. It is to be understood, however, that the spring elements alone represent an inventive aspect, so that the above-mentioned features in connection with the features of the shock absorber are also to be considered independently with regard to their structure and functionality.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• EP 6283 A [0003]
• EP 36994 A [0003, 0021]
• EP 250969 A [0003, 0021]
• DE 19548770 A [0003, 0021]
• DE 19548771 A [0003, 0021]
• EP 62835 A [0021]

Non-patent literature cited

• H. Piechota and H. Röhr in "Integralschaumstoffe", Carl Hanser-Verlag, Munich, Vienna 1975 described; D.J. Prepelka and J.L. Wharton in Journal of Cellular Plastics, March / April 1975, pages 87 to 98 and U. Knipp in Journal of Cellular Plastics, March / April 1973 [0025]
• DIN EN ISO 527 [0030, 0062]
• DIN ISO 7619-1 [0030]
• DIN 53504-S2 [0030, 0062]
• DIN ISO 7619-1 (3S) [0062]

Claims (16)

A shock absorber (1) with a longitudinal axis (2), wherein the shock absorber (1) is configured such that it deforms between an uncompressed and a compressed state with a restoring force, and in the compressed state a smaller length in the direction of the longitudinal axis (2 ) has as in the uncompressed state, containing a base body (9) which functions as a stop damper, the base body (9) partially or completely consisting of a volume-compressible material; characterized in that the base body (9) further contains at least one secondary spring element (11, 11 ') which is integrated in the base body (9) and the secondary spring element (11, 11') between a first length in the uncompressed state and a second length is resilient in the compressed state and the second length is smaller than the first length and partially or completely consists of a compact second material, and that the base body (9) has a first spring rate and the secondary spring element (11, 11 ') a second Comprises spring rate, which is lower than the first spring rate, wherein the spring rate is defined as the ratio with which the respective spring element can be compressed relative to its uncompressed base state. The shock absorbers after Claim 1 , characterized in that the base body (9) at least partially and preferably completely encapsulates the secondary spring element (11, 11 '). Shock absorbers according to one of the Claims 1 or 2 , characterized in that the secondary spring element (11, 11 ') is designed so that it has a predetermined block length when it is in the compressed state. Shock absorber according to one of the preceding claims, characterized in that the spring rate of the base body is in the range of more than 65%, preferably 70% or more and / or the spring rate of the secondary spring element (11, 11 ') in a range of 70% or less is, preferably 65% or less. Shock absorber according to one of the preceding claims, characterized in that the secondary spring element (11, 11 ') is selected from the following list: helical spring, preferably helical; Wave spring; A plurality of ring elements, preferably disc springs or washers, which are separated from one another in the direction of the longitudinal axis; or a deformable cage with restoring force. Shock absorber according to one of the preceding claims, characterized in that the secondary spring element (11, 11 ') is stiffer in the radial direction than the primary spring element. Shock absorber according to one of the preceding claims, wherein the material of the base body is a microcellular polyisocyanate polyaddition product. Shock absorber according to one of the preceding claims, wherein the material of the secondary spring element (11, 11 ') is selected from elastomer, metal, steel, steel alloy, aluminum, aluminum alloy, fiber composite material, or a combination of these materials. Bumper after Claim 8 , characterized in that the material of the secondary spring element has one, several or all of the following properties: a Young's modulus of 225 MPa or more, more preferably 750 MPa or more, or preferably a Young's modulus of 2200 MPa or lower, or particularly preferably a Young's modulus in a range from 800 MPa to 2200 MPa; a hardness of 40D or more, preferably 60D or more, or preferably a shore hardness of 90D or lower, or more preferably in the range of 60D to 90D; a tensile strength of 40 MPa or more, or preferably a tensile strength of 70 MPa or lower, or particularly preferably a tensile strength in a range from 40 MPa to 70 MPa; a density of 1.10 g / cm3 or higher, or preferably a density of 1.45 g / cm3 or lower, or particularly preferably in a range from 1.10 to 1.45 g / cm3. Shock absorber according to one of the preceding claims, characterized in that the second material of the secondary spring element comprises an elastomer or consists of this elastomer, and this elastomer is selected from the following list: - polyether-based polyurethane, - polyester-based polyurethane, - thermoplastic polyether-based polyurethane - thermoplastic polyurethane based on polyester, - semicrystalline thermoplastic - fiber composite material with thermoplastic polyurethane as the matrix material, the thermoplastic material preferably being polyester based. Shock absorber according to one of the preceding claims, characterized in that the secondary spring element (11, 11 ') is a wave spring and has a first end section (13'), an opposite second end (15) and a series of spring leaves (21) or comprises undulating rings (22) which are undulating in the direction of the longitudinal axis (L). Shock absorber after Claim 11 , characterized in that the spring leaves (21) or rings (22) and the end sections (13, 13 ', 15) are formed integrally with one another and the secondary spring element (11') has a plurality of joints (23, 25) or joining sections (28), wherein in each joining section one of the rings (22) is connected to one of the end sections (13 ', 15) or one of the adjacent rings. Shock absorber after Claim 12 , with all joining sections (28) two or adjacent joining sections being at an angle from one another, this angle preferably being in a range between 15 ° and 165 °, more preferably between 60 ° and 120 °, and particularly preferably between 75 ° ° and 105 °. Shock absorbers according to one of the Claims 11 until 13th wherein each merging section (28) comprises an integral part (30) extending in the direction of the longitudinal axis (L). The bumper of one of the Claims 11 until 14th wherein at least one of the end portions (13 ') of the secondary spring element (11') comprises a plurality of inwardly expanding projections (14) and / or a plurality of outwardly expanding projections (18). The bumper of one of the Claims 11 until 15th , wherein at least one of the end sections (13, 13 ', 15) of the secondary spring element (11, 11') comprises a plurality of material passages (27, 29) which extend in the direction of the longitudinal axis (L).

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