Method for producing a motor vehicle rim made of aluminum or an aluminum alloy for a wheel of a motor vehicle, and corresponding motor vehicle rim

Description

[0001] The invention relates to a method for producing a motor vehicle rim made of aluminum or an aluminum alloy for a wheel of a motor vehicle, wherein the motor vehicle rim has a rim base defined on opposite sides by an outer flange and an inner flange, a hub with a central recess and a bolt circle, and a rim center connecting the rim base and the hub, particularly engaging the rim base eccentrically in longitudinal section. The invention further relates to a motor vehicle rim.

[0002] For example, EP 0 301 472 B1 is known from the prior art. This describes a manufacturing process for light metal cast wheels for passenger cars, using a near-eutectic refined AISi alloy which, in addition to Al, contains a weight fraction of 9.5% to 12.5% ​​silicon and alloying components such as a maximum of 0.2% iron, a maximum of 0.05% manganese, a maximum of 0.1% titanium, a maximum of 0.03% copper, a maximum of 0.05% zinc, and a maximum of 0.05% of other impurities, and a total of a maximum of 0.15%. The wheels are removed from the casting mold and cooled after solidification.It is intended that the alloy contains at least 0.05 to a maximum of 0.15% by weight of magnesium and that the wheels are quenched in water from a temperature - measured on their surface - of at least 380 °C in internal areas or areas with mass concentrations, such as the hub and bowl of wheels, immediately upon removal from the casting mold.

[0003] Furthermore, the document DE 20 2014 100 377 U1 describes a vehicle wheel with a wheel body and a plurality of rim blades coupled to at least one side surface of the wheel body, wherein each of the rim blades has an air flow guide portion and an air flow auxiliary portion, wherein the air flow guide portion and the air flow auxiliary portion are arranged in a front and rear side on the rim blade.

[0004] The document DE 40 27 355 C2 also shows a double disc structure for motor vehicle wheels made of light metal alloy, comprising: a first and a second wheel disc which are formed separately from one another and detachably fastened to one another at their hubs by means of a plurality of first screw clamping devices and at their peripheral edges by means of a plurality of second screw clamping devices and which are rotatable as a unitary double wheel disc together with the wheel rim provided thereon; and ventilation holes which are formed in the corresponding intermediate regions between the hub and the peripheral edge of the two wheel discs, wherein the ventilation holes of the second wheel disc differ in size, shape and distribution from the ventilation holes of the first wheel disc, and wherein the intermediate regions and the wheel axis form a triangular configuration in cross-section.From US 8 651 584 B2 a motor vehicle rim with air conveying elements in the rim well area is also known.

[0005] It is an object of the invention to propose a method for producing a motor vehicle rim made of aluminum or an aluminum alloy for a wheel of a motor vehicle, which has advantages over known methods of this type, in particular enabling particularly rapid and cost-effective production of the motor vehicle rim with particularly filigree structures and also ensuring excellent heat dissipation from the motor vehicle rim.

[0006] This is achieved by a method for producing a motor vehicle rim with the features of claim 1. It is provided that the motor vehicle rim is produced in one piece and continuously in a casting mold by die-casting a casting material, wherein the motor vehicle rim is formed during die-casting with at least one air conveying element arranged to convey air in the axial direction with respect to a longitudinal center axis of the motor vehicle rim relative to an imaginary plane perpendicular to the longitudinal center axis and / or at least one surface enlargement element running in the circumferential direction along a circular line.

[0007] The motor vehicle rim is typically a component of the wheel of the motor vehicle, with the motor vehicle having multiple wheels, each of which has such a motor vehicle rim. The motor vehicle is in the form of a motor vehicle and therefore has more than two wheels, in particular exactly four wheels. The motor vehicle rim is explicitly intended and designed for use on such a motor vehicle designed as a motor vehicle. The motor vehicle rim is therefore not a generic motor vehicle rim, but is intended for use on the motor vehicle and designed accordingly.

[0008] The essential components of a motor vehicle rim are the rim well, the rim center, and the hub. The rim well and the hub are connected to one another via the rim center, with at least the rim well, the rim center, and the hub being formed integrally and from the same material. For this purpose, the rim well, the rim center, and the hub are formed simultaneously, namely during a single manufacturing step. Therefore, it is not intended to manufacture the rim well, the rim center, and the hub separately and subsequently attach them to one another. Rather, they are manufactured jointly, namely by pressure-casting the casting material in the mold.

[0009] The motor vehicle rim has a longitudinal central axis which in particular corresponds to a longitudinal central axis of the hub and preferably coincides or at least almost coincides with a later axis of rotation of the wheel. Viewed in the axial direction with respect to this longitudinal central axis, the rim well is delimited on opposite sides by the outer flange and the inner flange. The outer flange and the inner flange are therefore located on opposite sides of the rim well and enclose a tire receiving area of ​​the motor vehicle rim between them in longitudinal section with respect to the longitudinal central axis. The tire receiving area serves to accommodate a tire which, together with the motor vehicle rim, forms the wheel. The tire receiving area is delimited inwards in the radial direction by the rim well and on opposite sides in the axial direction by the outer flange and the inner flange.

[0010] Particularly preferably, the entire motor vehicle rim is delimited in the axial direction or, as viewed in longitudinal section, in a first direction by the outer flange and in a second direction by the inner flange, such that the outer flange and the inner flange define an overall extension of the motor vehicle rim in the axial direction, corresponding to a width of the motor vehicle rim. When the wheel is mounted on the motor vehicle, the wheel is rotatably mounted on a wheel carrier via a wheel bearing. After the wheel is mounted on the motor vehicle, the outer flange is located on a side of the motor vehicle rim facing away from the wheel carrier, and the inner flange is located on a side of the motor vehicle rim facing the wheel carrier.

[0011] The outer flange and the inner flange are in the form of a radial projection extending from the rim well and outward in a radial direction, again relative to the longitudinal center axis of the vehicle rim. Naturally, the outer flange and the inner flange are also formed integrally and from the same material as the rest of the vehicle rim, in particular the rim well, the center of the hub, and the hub. They are therefore formed simultaneously with the rest of the rim during the die-casting process.

[0012] The hub has a center recess and a bolt circle. The center recess is a central recess for accommodating a motor vehicle wheel hub, to which the wheel is attached during assembly. The wheel hub is rotatably mounted on the wheel carrier via the wheel bearing. The bolt circle consists of several holes arranged along an imaginary circle, each of which serves to accommodate a fastener used to attach the motor vehicle rim to the wheel hub. The fastener can be in the form of a screw, bolt, or the like.

[0013] The rim well and the hub are connected to each other via the rim center. The rim center is therefore located between the rim well and the hub in the radial direction relative to the longitudinal center axis. It extends radially from the hub to the rim well. For example, the rim center has several spokes that are arranged or configured spaced apart from one another in the circumferential direction. However, the rim center can also be continuous in the circumferential direction, in particular completely.

[0014] The rim center preferably engages the rim well off-center in the axial direction or, as viewed in longitudinal section, this means that it merges into the rim well in the axial direction away from a center point of the rim well. The rim center preferably engages at a distance from the center point of the rim well in the axial direction that is at least 10%, at least 20%, at least 30%, at least 40% or more based on the total extension of the rim well in the axial direction. For example, the rim center merges into the rim well at the end of the rim well as viewed in the axial direction. In this case, the rim center, as viewed in longitudinal section, merges into the rim well in overlap with the outer flange or the inner flange, preferably the former.Because the rim center engages the rim well off-center, the rim center is subjected to not only a radial force after the wheel is mounted on the vehicle, but also a bending moment in the axial direction, or in an imaginary plane that includes the longitudinal center axis of the vehicle rim. This has previously required a correspondingly solid rim center, requiring a high level of material. Of course, the rim center can also be positioned centrally on the rim well and / or the hub.

[0015] Viewed in longitudinal section, the rim well preferably has a greater extension in the axial direction than the rim center and the hub. In particular, the axial extension of the rim well is greater than the axial extension of the hub, which in turn is greater than the axial extension of the rim center. For example, the axial extension of the hub relative to the axial extension of the rim well is at most 50%, at most 40%, at most 30%, at most 25%, or at most 20%. The axial extension of the rim center relative to the axial extension of the rim well is, for example, at most 25%, at most 20%, at most 15%, at most 10%, or at most 5%.In particular, due to the rim center engaging off-center on the rim, the dimensions mentioned create a receptacle for the wheel hub and / or a brake disc attached to the wheel, which receptacle is encompassed by the rim base, the wheel hub and / or the brake disc being present in this receptacle after the wheel has been mounted on the motor vehicle.

[0016] The motor vehicle rim is made entirely of the same material, namely aluminum or, preferably, an aluminum alloy. This material is processed by die casting. During die casting, a mold is used to form the motor vehicle rim, and thus at least the rim base including the outer flange and the inner flange, the rim center, and the hub. The center recess, which can also be referred to as the wheel hub receptacle, is also preferably formed, at least partially, during die casting.

[0017] Die casting can be carried out at normal pressure or as vacuum die casting. Vacuum die casting is characterized by the fact that the casting mold is at least partially evacuated before and / or during the introduction of the casting material into the mold. This means that the casting mold is subjected to a negative pressure before and / or during the introduction of the casting material. Negative pressure is understood to be a pressure which is lower than the introduction pressure at which the casting material is introduced into the casting mold and / or the ambient pressure in an external environment of the casting mold. For example, the negative pressure in relation to the external pressure is at most 50%, at most 25%, at most 10% or at most 5%. For example, the residual pressure is between 50 mbar and 200 mbar. Residual pressure is understood to be the absolute pressure in the casting mold.

[0018] The casting mold is evacuated, for example, by means of a vacuum source which is fluidically connected to the casting mold for this purpose. In particular, the casting mold is evacuated even before introducing the casting material. For example, the casting material is introduced when, in particular only when, a certain negative pressure or residual pressure is reached in the casting mold. It can additionally or alternatively be provided that the casting mold is evacuated during the introduction of the casting material, that is to say the fluidic connection between the vacuum source and the casting mold is maintained during the introduction of the casting material into the casting mold and the vacuum source is further operated to evacuate the casting mold. Thereby, particularly delicate structures of the motor vehicle wheel can be produced.

[0019] For example, it is provided to first seal the casting mold using at least one seal, for example using a sealing cord, in particular a silicone sealing cord. The casting material is then metered into a casting chamber that is fluidically connected to the casting mold. For this purpose, the casting chamber is at least temporarily fluidically connected to a crucible in which the molten casting material is stored. The casting mold is then subjected to negative pressure and the casting material located in the casting chamber is forced into the casting mold, in particular by means of a pressurized piston. Preferably, the flow connection between the casting chamber and the crucible exists at the same time, in particular continues to exist. This means that the evacuation of the casting chamber also takes place while the casting material is being introduced.

[0020] During driving of the motor vehicle, heat may be introduced into the motor vehicle rim and / or at least one other element of the motor vehicle. The other element is, for example, a brake disc, a wheel carrier or the like. In order to at least dissipate the heat from the motor vehicle rim, the motor vehicle rim has at least one air conveying element and / or at least one surface enlargement element. In this case, exactly one air conveying element or several air conveying elements can be implemented. Additionally or alternatively, exactly one surface enlargement element or several surface enlargement elements can be formed on the motor vehicle rim. If reference is made to the air conveying element in the context of this description, the statements always apply to the at least one air conveying element or each of the several air conveying elements.The same applies to statements regarding the surface enlargement element, which are also always applicable to the at least one surface enlargement element or each of the plurality of surface enlargement elements.

[0021] It can be provided that only the at least one air conveying element is implemented on the motor vehicle rim, but not the surface enlargement element. Conversely, it can of course be provided that the surface enlargement element is present on the motor vehicle rim, but not the air conveying element. However, it is particularly advantageous for both the air conveying element and the surface enlargement element to be formed on the motor vehicle rim. Wherever the air conveying element and the surface enlargement element are mentioned in this description, the statements always apply to the respective element present. The joint mention of the air conveying element and the surface enlargement element does not mean that both elements are actually present, although this can of course be the case.

[0022] The air conveying element and the surface enlargement element are formed integrally and continuously with the vehicle rim. They are formed together with the vehicle rim during the die-casting process. Therefore, it is not intended to manufacture the air conveying element and the surface enlargement element independently of the vehicle rim and subsequently attach them to it. This enables particularly efficient production of the vehicle rim.

[0023] The air conveying element is designed in such a way that, when the motor vehicle rim rotates about its longitudinal center axis, it exerts a conveying effect on the air surrounding the motor vehicle rim. During the rotary movement of the motor vehicle rim, the air conveying element conveys the air in an axial direction relative to the longitudinal center axis, for example from an inner side of the motor vehicle rim towards an outer side of the rim or vice versa. With the aid of the air conveying element, an air flow is to be created in an axial direction when the motor vehicle is in operation, i.e. when the motor vehicle rim rotates, which air flow brings about efficient cooling of the motor vehicle rim and / or the at least one further element. For example, warm air can be discharged from the further element by means of the air conveying element, in particular by conveying the warm air present on the inner side of the rim towards the outer side of the rim or by discharging it onto the outer side of the rim.The rim inner side is understood to mean in particular a side of the motor vehicle rim which faces the wheel carrier, whereas the rim outer side is the side of the motor vehicle rim which faces away from the wheel carrier.

[0024] The additional element, for example the brake disc, is usually located on the inside of the rim, for example it is at least partially encompassed by the rim well so that it is ultimately arranged in the motor vehicle rim. Preferably, after the motor vehicle rim has been mounted on the motor vehicle, the additional element is connected to the motor vehicle rim in a rotationally fixed manner. The air conveying effect of the air conveying element is achieved by the adjustment of the air conveying element with respect to the imaginary plane, wherein the plane is perpendicular to the longitudinal center axis of the motor vehicle rim. The air conveying element can basically be plate-shaped in cross-section and exhibit the air conveying effect solely due to its adjustment. However, it can also be provided that the air conveying element is airfoil-shaped in cross-section, i.e. exists as a flow-technical profile.With such a design of the air travel element, a particularly efficient and effective conveyance of air is achieved.

[0025] In addition or alternatively to the at least one air conveying element, the motor vehicle rim has at least one surface enlargement element. The surface enlargement element also ultimately serves to dissipate heat. This is achieved by enlarging the surface of the motor vehicle rim, so that the heat is dissipated or removed from the motor vehicle rim via the surface enlargement element due to natural convention and / or forced convection. The surface enlargement element extends in the circumferential direction along the imaginary circular line, so that the surface enlargement element is annular at least in some regions, in particular only in some regions or continuously. The surface enlargement element encompasses the longitudinal center axis of the motor vehicle rim at least partially, for example only partially or completely.In particular, the surface enlargement element extends in the circumferential direction over at least 30°, at least 60°, at least 90° or at least 180°.

[0026] Of course, a particularly preferred embodiment of the motor vehicle rim is one in which the at least one surface enlargement element is present in addition to the at least one air conveying element. In such an embodiment, the air conveying element and the surface enlargement element are preferably arranged and designed such that the air flow caused by the air conveying element during the rotational movement of the motor vehicle rim flows against and / or over the surface enlargement element. Such a configuration of the motor vehicle rim enables particularly effective heat dissipation. For example, the surface enlargement element and the air conveying element are also connected or fastened to one another.

[0027] The described process for manufacturing car rims enables simple, fast, and cost-effective production of the rim, which can also have an extremely delicate structure and is also designed and constructed for effective heat dissipation. Rapid production is achieved in particular through die casting, which fills the mold much faster than with permanent mold casting or low-pressure casting, which is normally used to manufacture car rims. Overall, die casting allows the cycle time for car rims to be significantly increased, allowing a larger number of car rims to be produced in the same amount of time. The solidification time is also significantly shorter for die casting than for permanent mold casting.

[0028] A further development of the invention provides that the motor vehicle rim has, at least in some regions, a small wall thickness of at most 15 mm and / or a curvature with a small radius of curvature of at most 4 mm and / or a demoulding surface which runs in the axial direction and in the radial direction and / or in the axial direction and in the tangential direction with respect to a longitudinal central axis of the motor vehicle rim and which lies entirely in an imaginary plane, wherein the plane encloses an angle with the longitudinal central axis which is more than 0° and at most 4°. This preferably applies to the air conveying element and / or the surface enlargement element. It can therefore be provided that the air conveying element and / or the surface enlargement element have the small wall thickness and / or the curvature with the small radius of curvature, and / or that the demoulding surface is formed on them.

[0029] The motor vehicle rim produced by die casting is generally characterized by a particularly thin wall thickness and / or a curvature with a particularly small radius of curvature and / or by the presence of the demolding surface. The wall thickness is understood to be the thickness of the wall of the motor vehicle rim at at least one point. The thin wall thickness can therefore be present, for example, at the rim well, the outer flange, the inner flange, the rim center and / or the hub. The thin wall thickness is particularly preferably present at the rim center. Most preferably, the thin wall thickness represents the greatest wall thickness, for example the greatest wall thickness of the outer flange, the greatest wall thickness of the inner flange and / or the greatest wall thickness of the rim center. Of course, it can also be the greatest wall thickness of the rim well and / or the hub.

[0030] The small wall thickness is at most 15 mm, at most 10 mm, at most 7.5 mm, or at most 5 mm, but is preferably smaller. Thus, for example, it is at most 4 mm, at most 3 mm, at most 2 mm, or at most 1.5 mm. Conversely, the small wall thickness is particularly preferably at least 1.5 mm or at least 2 mm. In In other words, the thin wall thickness is, for example, at least 1.5 mm and at most 5 mm, at least 1.5 mm and at most 4 mm, at least 1.5 mm and at most 3 mm, at least 1.5 mm and at most 2 mm, or approximately or exactly 1.5 mm. However, it can also be at least 2 mm and at most 5 mm, at least 2 mm and at most 4 mm, at least 2 mm and at most 3 mm, or exactly 2 mm.

[0031] In addition to or as an alternative to the thin wall thickness, the curvature has a small radius of curvature. The curvature is a curvature of an outer surface or outer peripheral surface of the motor vehicle rim. The outer surface defines the outer boundary of a wall of the motor vehicle rim. The curvature can be present at any location on the motor vehicle rim, for example, at the rim well, the outer flange, the inner flange, the rim center, and / or the hub. The curvature is, in particular, a transitional curvature between two surfaces that—seen in section—are angled toward each other and are, for example, flat surfaces.

[0032] The curvature preferably extends over an angle of at least 30°, at least 45°, at least 60°, or at least 90°. The curvature has a small radius of curvature, which is at most 4 mm, but is preferably smaller. For example, the small radius of curvature corresponds to a radius of curvature of at most 3 mm, at most 2 mm, at most 1.5 mm, or at most 1 mm. Conversely, the radius of curvature can additionally be at least 0.25 mm, at least 0.5 mm, or at least 0.75 mm.

[0033] In addition to or alternatively to the thin wall thickness and / or the curvature with the small radius of curvature, the motor vehicle rim can have a demolding surface. The demolding surface is understood to be a flat surface that lies directly against the casting mold during die casting and along which the motor vehicle rim is demolded from the casting mold after die casting. The demolding surface extends at least in the axial direction and in the radial direction and / or - additionally or alternatively - in the axial direction and in the tangential direction, in each case with respect to the longitudinal center axis of the motor vehicle rim. In any case, the demolding surface extends in two mutually perpendicular directions and thus lies entirely in the imaginary plane.

[0034] Demolding of the car rim occurs in the same direction. For example, after die casting, a part of the mold is displaced in the direction of the longitudinal center axis, i.e., in the axial direction, to open the mold and remove the car rim from the mold. This means that a mold surface of the mold that rests against and forms the demolding surface during die casting is displaced along the longitudinal center axis after die casting. In a conventional process for producing a car rim, the demolding angle, i.e., the angle between the demolding surface and the longitudinal center axis, must be at least 5° to ensure proper demolding.

[0035] However, due to the one-piece, continuous formation of the motor vehicle rim by die-casting from aluminum or the aluminum alloy, a significantly smaller angle is possible. The angle between the demolding surface or between the plane completely accommodating the demolding surface and the longitudinal center axis is between infinitesimally more than 0° and 4°, inclusive of these values. It can therefore be provided that the demolding surface runs almost parallel to the longitudinal center axis, so that an almost parallel displacement of the casting mold surface and the demolding surface occurs during demolding. The angle of 0° is understood to mean that the plane and the longitudinal center axis lie within one another or run parallel to one another. The angle is, for example, at least 0.5°, at least 1°, or at least 1.5°. However, a maximum angle of 4° is provided.For example, the angle is 3° at most, 2.0° at most, 1.5° at most, 1.0° at most, or 0.5° at most. The smaller angles of 2.0° and less are preferred.

[0036] Preferably, the air conveying element and / or the surface enlargement element have the small wall thickness and / or the curvature with the small radius of curvature and / or the demolding surface. However, the air conveying element and the surface enlargement element are particularly preferably designed with at least the small wall thickness, which is particularly preferably at most 7.5 mm, at most 5 mm, or at most 2.5 mm. With such a design of the motor vehicle rim, the described cooling effect can be achieved while simultaneously keeping the weight of the motor vehicle rim low.

[0037] A further development of the invention provides that the air conveying element extends from the hub to the rim well and is manufactured with a radial load-bearing capacity that corresponds to at least 2.5%, at least 5%, at least 7.5%, or at least 10% of the radial load-bearing capacity of the rim center. The load-bearing capacity refers to the radial load-bearing capacity between the hub and the rim well.

[0038] The air conveying element extends radially from the hub to the rim base. The load-bearing capacity of the air conveying element should be less than the load-bearing capacity of the rim center. However, the load-bearing capacity should at least correspond to one of the specified values.

[0039] The load-bearing capacity of the rim center refers to the load-bearing capacity of the entire rim center, regardless of whether it is continuous or has multiple spokes. If multiple spokes are assigned to the rim center, the air conveying element has, for example, a load-bearing capacity in the radial direction that corresponds to at least 25%, at least 50%, or at least 75% of the load-bearing capacity of one of the spokes. Additionally or alternatively, however, the load-bearing capacity of the air conveying element is at most 75%, at most 50%, or at most 25% of the load-bearing capacity of one of the spokes. For example, the load-bearing capacity of the air conveying element is at least 25% and at most 75%, at least 25% and at most 50%, or exactly or approximately 25% of the load-bearing capacity of one of the spokes.

[0040] For example, each of the multiple spokes is assigned at least one air conveying element, in particular exactly one air conveying element. Preferably, the respective air conveying element is arranged on the corresponding spoke. Preferably, the air conveying element extends from the respective spoke and is continuously connected to the spoke in the radial direction from the inside to the outside. In this respect, for example, the number of air conveying elements corresponds to the number of spokes. However, it can also be provided that the number of air conveying elements is greater or smaller than the number of spokes. For example, only every second, every third, or every fourth spoke is assigned an air conveying element. Conversely, each of the spokes can also be assigned a plurality of air conveying elements, which are arranged on the respective spoke at a distance from one another in the circumferential direction. This makes it possible to achieve particularly effective heat introduction.

[0041] A further development of the invention provides that the rim center is formed with a plurality of spokes spaced apart from one another in the circumferential direction with respect to a longitudinal center axis of the motor vehicle rim. Such a design of the rim center is used in particular to reduce the weight of the motor vehicle rim, but also to achieve better damping. The rim center is therefore not solid and continuous in the circumferential direction, but is composed of the plurality of spokes arranged spaced apart from one another in the circumferential direction. Preferably, each of the plurality of spokes extends radially from the hub to the rim well, thus connecting the hub and the rim well to one another. For example, at least three spokes, at least four spokes, at least five spokes, or at least six spokes are provided. For example, at least 10, at least 14, or at least 18 spokes are realized.Preferably, there are a maximum of 30 spokes or a maximum of 20 spokes. For example, each of the spokes extends circumferentially over a maximum of 30° or less, preferably a maximum of 15° or a maximum of 10°.

[0042] It can be provided that the spokes have a constant extension in the circumferential direction, i.e. starting from the rim well up to the hub. However, a branching of at least one of the spokes or several or each of the spokes can also be provided, so that the respective spoke is divided into several partial spokes. For example, the spoke initially extends radially outwards from the hub and divides at a division point into several partial spokes which run parallel to one another, in particular in the circumferential direction. After the division point, the partial spokes therefore run at a distance from one another up to the rim well and engage thereat at a distance from one another. It can be provided that a longitudinal center axis of at least one of the spokes, in particular the longitudinal center axes of several or all of the spokes, intersects the longitudinal center axis of the motor vehicle rim or is even perpendicular to it.This ensures a particularly optimal transmission of force from the center of the rim or from the spokes into the hub.

[0043] A further development of the invention provides that the motor vehicle rim is manufactured in some regions with a first wall thickness of more than 15 mm, in particular at least 17.5 mm or at least 20 mm, and in some regions with a second wall thickness corresponding to the small wall thickness. For example, it is provided that the motor vehicle rim is manufactured in some regions with a first wall thickness of more than 5 mm, in particular at least 7.5 mm or at least 10 mm, but at most 20 mm, and in some regions with a second wall thickness corresponding to the small wall thickness. The second wall thickness is preferably at least 1.5 mm or at least 2 mm and at most 15 mm, at most 10 mm, at most 7.5 mm or at most 5 mm, preferably at most 3 mm, at most 2.5 mm or at most 2 mm.The motor vehicle rim does not have a thin wall thickness throughout, but is composed of several parts, some of which have the first wall thickness and others the second wall thickness. The first wall thickness is generally greater than the second wall thickness, for example by a factor of at least 1.5, at least 2.0, or at least 2.5. For example, the first wall thickness and the second wall thickness are both implemented in the center of the rim. In particular, each of the spokes - if present - can have partially the first wall thickness and partially the second wall thickness. This results in a particularly high load-bearing capacity of the motor vehicle rim while maintaining an extremely delicate design.

[0044] A further development of the invention provides that the low wall thickness is used in a region lying in the circumferential direction between two spokes, so that the two spokes are connected to one another via an intermediate storage element produced during die casting, which has the low wall thickness at least in some regions, in particular continuously. The region lying in the circumferential direction between the two spokes can also be referred to as the inter-spoke region. The inter-spoke region extends in the circumferential direction between the two spokes and is delimited in the radially inward direction by the hub and in the radially outward direction by the rim well. In this respect, the inter-spoke region is present at the edge of the motor vehicle rim.

[0045] The intermediate spoke area is now at least partially or even completely provided with the intermediate spoke element, so that the area between the two spokes is at least partially or even completely closed with the intermediate spoke element. The intermediate spoke element has the low wall thickness. The two spokes, however, can have a greater wall thickness than the low wall thickness, for example a wall thickness corresponding to the first wall thickness. Of course, it can also be provided that the two spokes are designed with the low wall thickness. In this case, the low wall thickness is also used for the intermediate spoke element, in particular continuously, or a wall thickness that is less than the low wall thickness. The intermediate spoke element helps achieve excellent aerodynamic properties for the motor vehicle rim.

[0046] A further development of the invention provides that the interspoke element is configured to completely fill an area that is bounded circumferentially by the two spokes, radially inward by the hub, and radially outward by the rim base. Such a configuration has already been mentioned above. The interspoke element thus completely fills the interspoke area or completely seals it. This achieves particularly good aerodynamic properties.

[0047] A further development of the invention provides that the air conveying element and / or the surface enlargement element are formed starting from the rim center, in particular from the at least one spoke. The air conveying element or the surface enlargement element preferably extends away from the rim center in the axial direction, so that it has a free end on its side facing away from the rim center. In the case of the air conveying element, the free end can be in the form of a straight line or curved, in particular with a curvature that is constant or changing in the radial direction from the inside to the outside or vice versa. The free end of the surface enlargement element is preferably circular or at least partially circular. The surface enlargement element is therefore preferably hollow-cylindrical, in particular hollow-circular-cylindrical.If the rim center comprises the multiple spokes, the at least one air conveying element is preferably attached to at least one of the spokes. It has already been pointed out that multiple air conveying elements can also be assigned to the multiple spokes. In the case of multiple spokes, the surface enlargement element preferably connects multiple spokes to one another, thus engaging several of the spokes, in particular all of the spokes. In the latter case, it is preferably continuous in the circumferential direction, thus completely encompassing the longitudinal center axis of the motor vehicle rim. The described configuration enables a particularly high cooling effect of the motor vehicle rim.

[0048] The invention provides that the air conveying element and / or the surface enlargement element are formed on the inside of the motor vehicle rim. In other words, the air conveying element or the surface enlargement element extends in the axial direction, i.e., viewed in longitudinal section, in the direction of the inner flange. As a result, the air conveying element or the surface enlargement element are preferably completely accommodated in the motor vehicle rim, also viewed in longitudinal section. Ideally, the air conveying element and / or the surface enlargement element are arranged such that they are not visible or only barely visible from the outside of the rim under normal observation. This achieves an excellent visual impression of the motor vehicle rim despite the air conveying element or the surface enlargement element.

[0049] A further development of the invention provides that the surface enlargement element is formed starting from the air conveying element. The surface enlargement element thus extends in the circumferential direction starting from the air conveying element. For example, it extends in turn to the air conveying element, so that the surface enlargement element engages the air conveying element on both sides. However, it can also be provided that the surface enlargement element extends starting from one of several air conveying elements to another of the several air conveying elements. This allows a particularly thin wall thickness of the air conveying element to be achieved because it is supported by the surface enlargement element.

[0050] A further development of the invention provides that the air conveying element is designed to extend radially from the hub to the rim base relative to the longitudinal center axis. This has already been pointed out above.

[0051] A further development of the invention provides that the air conveying element, viewed in longitudinal section, is designed with an extension in the axial direction that corresponds at most to the extension of the rim center in the same direction or is at most 50%, at most 40%, at most 30%, at most 20%, or at most 10% greater than this. Conversely, viewed in longitudinal section, the air conveying element has, for example, an extension in the axial direction that corresponds at least 50%, at least 75%, or at least 100% to the extension of the rim center in this direction. Such a design ensures an excellent visual impression of the motor vehicle rim while simultaneously ensuring high load-bearing capacity.

[0052] A further development of the invention provides that the casting mold used in die casting is part of a die casting tool, in particular a two-plate die casting tool or a three-plate die casting tool, and the casting material is introduced into the casting mold through at least one injection opening, in particular through several injection openings. The three-plate die casting tool is characterized in that its sprue system is located in a different plane than the injection opening. The three-plate die casting tool has three plates, namely a first plate, a second plate, and a third plate. Between the first plate and the second plate, there is preferably at least one sprue channel, via which the injection opening is fluidically connected to an inlet opening.

[0053] The casting material is fed into the casting mold through the inlet opening. The motor vehicle rim is formed between the second plate and the third plate. This means that the second plate and the third plate form the actual casting mold. The at least one sprue and the motor vehicle rim to be produced are located on opposite sides of the second plate. The casting material is preferably introduced into the casting mold through several injection openings. The several injection openings are preferably each fluidically connected to the inlet opening via the sprue or via several sprues. The use of the two-plate die casting tool or the three-plate die casting tool enables particularly simple and rapid production of the motor vehicle rim.

[0054] A further development of the invention provides that the motor vehicle rim is made of AlSi10MnMgZn. This aluminum alloy serves as the casting material. The aluminum alloy has excellent strength properties for the motor vehicle rim. For example, an AlSi alloy is used as the casting material, which contains the following components: 6.5 wt% to 12.0 wt% Si, a maximum of 0.8 wt% Mn, 0.25 wt% to 0.6 wt% Mg, 0.08 wt% to 0.5 wt% Zn, a maximum of 0.3 wt% Zr, a maximum of 0.025 wt% Sr, a maximum of 0.5 wt% impurities and the remainder Al. The alloy can contain at least one of the following optional components: a maximum of 0.2 wt% V, a maximum of 0.2 wt% Mo, a maximum of 0.3 wt% Sn, a maximum of 0.3 wt% Co and a maximum of 0.2 wt% Ti.

[0055] Such an alloy is particularly suitable for the production of motor vehicle rims because it enables the realization of particularly delicate structures. The proportion of Mn is preferably greater than 0 wt.%, for example it is 0.2 wt.% or 0.3 wt.% on the one hand, and 0.8 wt.% on the other. The proportion of Mg is, for example, at most 0.5 wt.%. The proportion of Zn is preferably at most 0.35 wt.%. More preferably, the proportion of Sr is greater than 0 wt.%, in particular it is 0.006 wt.% to 0.025 wt. The aluminum alloy particularly preferably contains Cr, namely at most 0.3 wt.%. Impurities are understood to mean at least one element of the periodic table that is present in the alloy without deliberate addition. The impurities can of course also contain several of these elements.

[0056] A further development of the invention provides for the motor vehicle rim to be heat-treated after die-casting. The heat treatment is, for example, annealing the motor vehicle rim. The annealing comprises at least heating the motor vehicle rim to a specific temperature, which can also be referred to as the holding temperature, holding the motor vehicle rim at the holding temperature, and subsequently cooling it from the holding temperature, in particular to a temperature of no more than 200°C or to an ambient temperature.

[0057] Heat treatment may be performed on the entire vehicle rim. However, it can also be performed only locally, so that heat is only introduced into the vehicle rim at a specific location, resulting in a higher temperature at the heat-treated area than at other areas of the vehicle rim where heat treatment is not performed.

[0058] Additionally or alternatively, the heat treatment can be performed differently locally. This means that a first region of the motor vehicle rim is subjected to a first heat treatment, and a second region of the motor vehicle rim is subjected to a second heat treatment that differs from the first heat treatment. For example, a first holding temperature is used during the first heat treatment, and a second holding temperature is used during the second heat treatment, which is different from the first holding temperature.

[0059] The invention further relates to a motor vehicle rim made of aluminum or an aluminum alloy for a wheel of a motor vehicle, in particular manufactured according to the embodiments in the context of this description, wherein the motor vehicle rim has a rim base delimited on opposite sides by an outer flange and an inner flange, a hub with a center recess and a bolt circle and a rim center connecting the rim base and the hub to one another, in particular engaging off-center on the rim base in longitudinal section.

[0060] It is provided that the motor vehicle rim is produced in one piece and continuously in a casting mold by die-casting a casting material, wherein the motor vehicle rim has at least one air conveying element arranged to convey air in the axial direction with respect to a longitudinal center axis of the motor vehicle rim relative to an imaginary plane perpendicular to the longitudinal center axis and / or at least one surface enlargement element running in the circumferential direction along a circular line, which is formed during die-casting.

[0061] The advantages of such a design of the motor vehicle rim and such a manufacturing procedure have already been pointed out above. Both the motor vehicle rim and the method for its manufacture can be further developed in accordance with the explanations within the scope of this description, so reference is made to these in this regard.

[0062] The invention will be explained in more detail below with reference to the exemplary embodiments shown in the drawing, without limiting the invention. The only Figure a schematic longitudinal section through a motor vehicle rim for a wheel of a motor vehicle.

[0063] The figure shows a schematic longitudinal section through a motor vehicle rim 1 for a wheel of a motor vehicle. The motor vehicle rim 1 has, as its essential components, a rim well 2, a rim center 3, and a hub 4. The motor vehicle rim 1 is shown in longitudinal section with respect to a longitudinal center axis 5 of the motor vehicle rim 1. The rim well 2 is bounded in the axial direction on the one hand by an outer flange 6 and on the other hand by an inner flange 7, which extend outwards from the rim well 2 in the radial direction with respect to the longitudinal center axis 5. It should also be noted that the axial extent of the rim well 2 extends to a respective outer end of the outer flange 6 and the inner flange 7, respectively. The axial extent of the rim well 2 therefore includes the axial extents of the outer flange 6 and the inner flange 7.

[0064] The rim well 2 and the hub 4 are connected to each other via the rim center 3. The rim center 3 thus engages both the rim well 2 and the hub 4 and extends from the hub 4 to the rim well 2. The hub 4 has a central recess 8, which is located centrally on the hub 4 with respect to the longitudinal center axis 5 and extends completely through it in the axial direction. In addition, the hub 4 has a bolt circle 9 with several bores 10, each of which serves to receive a fastening means by means of which the motor vehicle rim 1 can be or is fastened to a wheel hub of the motor vehicle.

[0065] In the exemplary embodiment shown here, the rim center 3 has a plurality of spokes 11, which are arranged spaced apart from one another in the circumferential direction. Each of the spokes 11 extends from the hub 4 to the rim well 2 in the circumferential direction. Between the spokes 11 there is an intermediate spoke region, which is delimited in the circumferential direction by the spokes 11, in the radially inward direction by the hub 4, and in the radially outward direction by the rim well 2. In this intermediate spoke region, an intermediate spoke element can be formed, which, for example, completely fills the intermediate spoke region. At least the intermediate spoke element 12 has a small wall thickness of at most 5 mm. In order to achieve this, the motor vehicle rim 1 is manufactured in one piece and continuously in a casting mold by die-casting a casting material. Aluminum or an aluminum alloy is used as the casting material.

[0066] In order to ensure good cooling of the motor vehicle rim 1, it has at least one air conveying element 12 (of which only one is shown as an example) and at least one surface enlargement element 13. In the exemplary embodiment shown here, several surface enlargement elements 13 are realized, of which only some are shown as examples.

[0067] The air conveying element 12 serves to convey air in the axial direction with respect to the longitudinal center axis 5. The flow direction of the air, which is achieved by means of the air conveying element 12 during a rotational movement of the motor vehicle rim 1 about the longitudinal center axis 5, is indicated by way of example by the arrows 14. The air conveying element 12 extends from the spoke 11; preferably, each of the spokes 11 is assigned such an air conveying element 12 (not shown). The air conveying element 12 is preferably designed with a small wall thickness of at most 15 mm, at most 10 mm, at most 7.5 mm, at most 5 mm, or less. In particular, the air conveying element 12 has a wall thickness of at most 2.5 mm, at most 2 mm, at most 1.5 mm, or at most 1 mm.

[0068] The surface enlargement element 13 extends from the spoke 11 or spokes 11 in the axial direction toward the inner horn 7. If, as here, several surface enlargement elements 13 are present, they are arranged spaced apart from one another in the radial direction. For example, starting from the rim center 3, they each have the same extension in the axial direction. They can be offset from one another in the axial direction, for example due to an offset and / or a curvature of the rim center 3. The surface enlargement element 13 runs in the circumferential direction along a circular line. Particularly preferably, the surface enlargement element 13 is circular or annular in shape. In this respect, it is in the form of a hollow circular cylinder, which is arranged with a first end face at the rim center 3 and has a free end at its second end face.

[0069] The described design of the motor vehicle rim 1 achieves an extremely delicate appearance and, at the same time, ensures cost-effective and rapid production of the motor vehicle rim 1 due to the die-casting process. Furthermore, excellent strength values ​​are achieved by die-casting the aluminum or aluminum alloy, and effective heat dissipation from the motor vehicle rim 1 is ensured due to the air conveying element 12 and / or the surface enlargement element 13. LIST OF REFERENCE SYMBOLS:

[0070] 1Motor vehicle rim 2Rim well 3Rim center 4Hub 5Longitudinal center axis 6Outer flange 7Inner flange 8Center recess 9Bolt circle 10Bore 11Spoke 12Air conveying element 13Surface enlargement element 14Arrow

Claims

1. Method for producing a motor vehicle rim (1) made of aluminum or an aluminum alloy for a wheel of a motor vehicle, wherein the motor vehicle rim (1) has a rim well (2) delimited on opposite sides by an outer horn (6) and an inner horn (7), a hub (4) with a central recess (8) and a bolt circle (9), and a rim center (3) connecting the rim well (2) and the hub (4) to one another, characterized in that the motor vehicle rim (1) is produced in one piece and continuously in a casting mold by die casting of a casting material, wherein during the die casting at the motor vehicle rim (1), starting from the rim center (3), on the inside of the rim, at least one air conveying element (12) installed for conveying air in the axial direction with respect to a longitudinal central axis (5) of the motor vehicle rim (1) relative to an imaginary plane perpendicular to the longitudinal central axis (5) and / or at least one surface enlargement element (13) extending in the circumferential direction along a circular line is formed.

2. Method according to claim 1, characterized in that the motor vehicle rim - has at least in some areas a low wall thickness of at most 15 mm, and / or - has a curvature with a low curvature radius of at most 4 mm, and / or - has a demolding surface which extends in the axial direction and in the radial direction and / or in the axial direction and in the tangential direction relative to the longitudinal central axis (5) of the motor vehicle rim (1), and which lies completely in an imaginary plane, wherein the plane subtends with the longitudinal central axis an angle which is more than 0° and at most 4°.

3. Method according to any one of the preceding claims, characterized in that the rim center (3) is formed with a plurality of spokes (11) spaced apart in the circumferential direction relative to the longitudinal central axis (5) of the motor vehicle rim (1).

4. Method according to any one of the preceding claims, characterized in that the surface enlargement element (13) is formed starting from the air conveying element (12).

5. Method according to any one of the preceding claims, characterized in that the air conveying element (12) is formed extending in the radial direction relative to the longitudinal central axis (5) from the hub (4) to the rim well (2).

6. Method according to any one of the preceding claims, characterized in that the air conveying element (12) is formed, viewed in longitudinal section, with a maximum extension in the axial direction which is equal to an extension of the rim center (3) in the same direction or is at most 50% greater than the latter.

7. Method according to any one of the preceding claims, characterized in that the casting mold used in the die casting is part of a die-casting die and the casting material is introduced into the casting mold through at least one injection opening.

8. Motor vehicle rim (1) made of aluminum or an aluminum alloy for a wheel of a motor vehicle, produced according to one or more of the preceding claims, wherein the motor vehicle rim (1) has a rim well (2) delimited on opposite sides by an outer horn (6) and an inner horn (7), a hub (4) with a central recess (8) and a bolt circle (9), and a rim center (3) connecting the rim well (2) and the hub (4) to one another, characterized in that the motor vehicle rim (1) is produced in one piece and continuously in a casting mold by die casting of a casting material, wherein the motor vehicle rim (1) has, starting from the rim center (3), on the inside of the rim, at least one air conveying element installed for conveying air in the axial direction with respect to a longitudinal central axis (5) of the motor vehicle rim relative to an imaginary plane perpendicular to the longitudinal central axis (5) and / or at least one surface enlargement element (13) which extends in the circumferential direction along a circular line and which is formed during the die casting.