Component group for a vehicle, in particular for a vehicle seat, and method for painting a component group of this type

Abstract

The invention relates to a component group (2) for a vehicle and to a method for painting a component group (2) of this type with the aid of cathodic dip coating, wherein the component group (2) has a first component (4) and a second component (6) which are secured to one another such that they can rotate about an axis of rotation (D) extending in an axial direction (A), wherein the first component (4) has a bearing bore (8), in which a cast bearing bush (10) is seated, which is formed by partially casting around the first component (4), and the two components (4, 6) are connected via a bearing pin (18) guided through the bearing bush (10), wherein the bearing bush (10) is formed from plastic with conductive additives contained therein, such that a conductive connection between the two components (4, 6) is formed by means of the bearing bush (10) and the bearing pin (18) guided therein. In this way, during the cathodic dip coating, only one of the components (4, 6) needs to be electrically contacted and it is ensured that the two components are at a suitable voltage potential.

Description

[0001] Page 1

[0002] 2024 167 WO

[0003] Description

[0004] Component group for a vehicle, in particular for a vehicle seat, and method for painting such a component group

[0005] The invention relates to a component assembly for a vehicle, in particular for a vehicle seat, comprising a first component and a second component rotatably mounted to one another about an axis of rotation, the first component having a bearing hole in which a bearing bushing is inserted. The invention further relates to a method for painting such a component assembly.

[0006] In the automotive sector, cathodic dip coating (e-coating) is a common method for painting components or assemblies. In this process, the component to be coated is immersed in a bath containing charged paint particles. The component becomes electrically charged, causing the charged paint particles to adhere to the surface and form a homogeneous coating. To electrically charge the component, it must be connected to a potential source.

[0007] When coating component groups where several components are attached to one another, it must be ensured that each component is electrically charged. For component groups where, for example, two components are mounted together via a non-conductive plastic bearing bushing, both components must be connected to the electrical potential.

[0008] For efficient painting, numerous component groups are typically mounted on a common rack, which is immersed in the dipping bath and through which the voltage potential for the component groups is supplied. Since the components within each group must be electrically contacted separately (page 2), this limits the possible arrangements and results in a large space requirement, thus limiting the number of component groups per rack.

[0009] Cathodic dip coating is known, for example, from EP 3 891 323 B1, in which a current flow between two adjacent components is achieved via an electrically conductive contact disc.

[0010] EP 3 498 956 B1 describes a hinge in which two hinge parts are rotatably mounted to one another via a plastic bushing. A conductive element is located between a bearing pin and the bushing to electrically bridge the non-conductive bushing. For this purpose, the bushing is designed in two parts, and the conductive element is inserted as a ring in a space between the two parts. This document also describes, as a prior art, that when using plastic bushings in cathodic dip coating, a high number of coating defects can occur due to insufficient electrical conductivity between the components and the resulting arcing. When using electrically conductive plastic bushings, a problem is described as strong coating adhesion on the outer surface of the hinge, which can detach.

[0011] Based on this, the invention aims to provide a component group and a method for coating such a component group, whereby a reliable homogeneous coating is achieved and a compact arrangement on a holding frame for efficient immersion coating is enabled.

[0012] The problem is solved according to the invention by a component assembly for a vehicle, in particular for a vehicle seat, comprising a first component and a second component rotatably mounted to one another about an axis of rotation extending in an axial direction. The first component has a bearing hole in which a bearing bushing is cast, the bushing being formed by partially overmolding the first component. The two components are connected to each other via a bearing bolt guided through the bearing bushing, the bearing bushing being made of plastic containing conductive additives. The bearing bushing thus has a plastic matrix with embedded conductive additives. A conductive connection between the two components is formed via the bearing bushing and the bearing bolt. A layer of lacquer is applied to the component assembly.

[0013] The two components and the bearing bolt are electrically conductive and are usually made of a metallic material.

[0014] The two components are connected to each other in the axial direction, and the bearing bolt usually has a locking head on both sides, via which the two components are positively locked in the axial direction.

[0015] The thickness of the paint layer is typically in the range of 10pm to 35pm, and especially in the range of 15pm to 20pm.

[0016] In this context, a cast bearing bushing is understood to be one formed by, for example, a pressureless casting process or a pressure-controlled injection molding process, in which the first component is placed in a suitable mold, into which the plastic material containing the conductive additives is then introduced to form the cast bearing bushing. The particular advantage of the cast plastic bushing is that it fits directly against the bearing bore, thus achieving intimate contact with, for example, the bore edge of the bearing bore.

[0017] With such component groups, the general problem is that, due to the sequential arrangement of numerous components, each component must be provided with a certain manufacturing or assembly tolerance, resulting in a chain of tolerances that ultimately leads to a component connection subject to tolerances. By overmolding the first component, at least one tolerance effect between the bearing hole and the bearing bushing is compensated for. Page 4

[0018] Investigations have shown that the use of a cast plastic bushing containing conductive additives, specifically due to the direct contact between the cast bushing and the first component, results in a good electrically conductive connection between the two components via the plastic bushing. This electrically conductive connection runs from the first component, through the plastic bushing, to the bearing pin, which is supported by the plastic bushing and is ultimately connected to the second component.

[0019] Such a prepared component group has proven particularly suitable for cathodic dip coating, and in the inventive method, such an uncoated component group is placed in the dip bath. The coating is applied using the cathodic dip coating process, which is known per se. A homogeneous, high-quality coating is formed. Due to the conductive connection between the two components to be coated, it is sufficient that only one of the components on the holding frame needs to be connected to an electrical potential. This is usually achieved by a suitable suspension of the component on the holding frame, so that the electrical contact and connection to the potential is established via the holding frame at a suspension point.

[0020] In a preferred embodiment, the bearing bushing has at least one radially extending bushing rim with which the bearing bushing engages a hole rim of the bearing bore. Furthermore, the bearing pin has a collar with which it rests on the bushing rim. The bushing rim is designed in the manner of a flange, particularly a circumferential one. A positive locking connection in the axial direction is achieved via the collar. The collar forms a locking head, as previously described. The bushing rim is therefore located between the collar and the first component and is, in particular, clamped and secured between these two parts. This results in a particularly close contact between the bearing pin, the bearing bushing, and the first component, which, as described on page 5, positively influences the desired electrically conductive connection between the first component and the bearing pin.Due to the recasting process, the bushing edge is always in direct contact with the edge of the bearing hole.

[0021] In a further development, the bearing bushing has two axially opposing, radially extending bushing edges that encompass the bore edge on both sides in the axial direction. The bearing bushing is therefore positively locked and, in particular, free of play in the bearing bore on both sides.

[0022] In particular, the second component rests directly against one of the two bushing collars. Furthermore, the bearing bolt is preferably connected directly to the second component via a second locking head. The bearing bolt is generally designed, for example, as a screw bolt or a rivet bolt. The two locking heads are formed by a bolt head on one side and a nut / nut-like connection (in the case of a screw bolt) or a formed rivet head (in the case of a rivet bolt) on the other side. The previously described collar of the bearing bolt is formed, in particular, by the bolt head or, alternatively, by the nut or the formed head.

[0023] The two components are usually clamped against each other by a defined preload, which is applied via the bearing bolt with the axially double-sided locking heads, thereby reliably ensuring the electrically conductive connection between the individual parts.

[0024] In a preferred embodiment, projections are formed on at least one bushing edge against which the collar of the bearing pin is pressed. These projections are particularly nub-like and / or evenly distributed around the circumference of the bushing edge. These projections increase the contact force towards the collar in the area of ​​each projection, effectively creating a multitude of point contacts. This improves the conductivity between the two parts. Page 6

[0025] During the casting process, a casting skin typically forms, which usually consists only of insulating plastic material and not the electrically conductive additives. As a special effect of the cast bearing bushing, the casting process therefore reduces the electrical conductivity, thus increasing the contact resistance to the bearing pin. Sufficient conductivity is achieved despite this casting skin, specifically through the previously described raised areas and, more generally, through the close contact between the bearing pin and the bearing bushing, particularly between the collar and the bushing edge. These raised areas, in particular, reduce the electrical contact resistance between the bearing pin and the bearing bushing.

[0026] The casting skin is present at least in those areas where there is no contact with the bearing pin. As already mentioned, this casting skin forms an electrically insulating layer that increases the contact resistance, or rather, acts as an electrical insulator. Therefore, this insulating casting skin is present in exposed surface areas of the bearing bushing that come into contact with the immersion bath during painting.

[0027] As mentioned previously, the initially unpainted component assembly is painted by immersing the entire assembly in the cathodic dip coating bath. After the coating process, the component assembly is therefore painted, with the bearing bushing, in a preferred embodiment, remaining free of paint. Despite its conductivity, which contributes to both components being electrically charged during coating, the bearing bushing itself, or at least its free surface areas, is not electrically charged or not sufficiently charged. Therefore, the charged paint particles do not adhere to these free surface areas of the bearing bushing where the dip bath liquid can reach. This is also achieved, in particular, by the described casting skin, which acts as an electrical insulator.In its painted state, only the metallic components of the assembly—the first component, the second component, and the bearing pin—have a paint layer as desired, while the plastic bearing bushing remains unpainted. This prevents paint from flaking off the bearing bushing during operation. Page 7.

[0028] In a preferred embodiment, the first component further comprises a second bearing hole in which a second cast bearing bushing is formed by partially overmolding the first component. This second bearing bushing is also made of plastic containing conductive additives. Preferably, both bearing bushings are made of the same material, and more preferably, both bearing bushings are made of the identical material.

[0029] In a further appropriate step, the remaining storage box is free of lacquer.

[0030] The second bearing bushing is specifically a free bearing bushing, meaning that initially no other component is mounted on it. Only during subsequent assembly after dip coating is a further (third) component attached to the second bearing bushing, which can be pivotally mounted to the first component.

[0031] Electrically conductive additives include, for example, carbon black particles, graphite particles, and / or metal particles, often in powder form. Carbon fibers, metal fibers, or so-called carbon nanotubes can also be used.

[0032] In a preferred embodiment, the admixtures are conductive fibers, preferably carbon fibers. Here, fibers are generally understood to be elongated elements whose length-to-diameter ratio is at least five, preferably at least ten. Preferably, the fibers have, for example, a length in the range of 0.15 mm to 1.5 mm and a diameter of preferably 0.08 to 0.15 mm.

[0033] A particular advantage of the fibers is that they intersect, as their orientation within the polymer matrix is ​​typically random, at least in some areas. Each fiber can touch several other fibers (see page 8). This creates a kind of fiber network, which significantly contributes to the desired conductivity.

[0034] The proportion of impurities, especially fibers, is preferably in the range between 10 vol.% and 60 vol.%, particularly in the range between 10 vol.% and 40 vol.%.

[0035] The remaining material of the bearing bushing preferably consists exclusively of the plastic matrix. The only additives preferably used are fibers, as previously described.

[0036] In a preferred embodiment, the bearing bushing is sufficiently temperature-resistant and, for example, temperature-resistant up to at least 150°C and, in particular, up to 180°C or higher. Due to recent developments that aim for lower process temperatures, it is preferably still sufficient if the bearing bushing is temperature-resistant up to a maximum of 210°C or up to a maximum of 180°C. Temperature resistance is understood to mean, in particular, that the bearing bushing can withstand such a temperature for a specified period of, for example, one hour or at least for the duration of the e-coating process, without the plastic being damaged and, for example, softening and / or decomposing.

[0037] The temperature resistance ensures, in particular, that the bearing bushing can withstand the thermal stresses during painting. These thermal stresses are determined firstly by the temperature of the immersion bath and, secondly, especially by the drying process following the immersion. The total temperature load can reach up to 180°C, for example.

[0038] The bearing bushing is typically made of PBT (polybutylene terephthalate) or polyamide, for example PA6 or PA66. The plastic matrix therefore consists entirely of (exactly) one of these materials. Alternatively, a mixed compound can be used for the plastic matrix. Page 9

[0039] The component group described here is specifically a component group for a vehicle seat, particularly a passenger car seat. Specifically, the first component is a swivel lever and the second component is a side panel of a seat support.

[0040] The component group, when assembled, forms part of an adjustment mechanism for the vehicle seat, for example, for height adjustment. An additional pivoting connection to a third component, which is attached to a seat frame, is achieved via the second bearing hole described earlier, with its second bearing bushing. In its final assembly state, the pivot lever with the two bearing holes is, for example, part of a four-joint kinematic system used for adjusting the height of the vehicle seat.

[0041] An embodiment of the invention is explained in more detail below with reference to the figures. These show, in some cases in simplified form:

[0042] FIG 1 shows a component group with a pivot lever as the first component, which is pivotably attached to a seat support of a vehicle seat as the second component.

[0043] FIG 2 shows a sectional view through the component group along the pivot lever,

[0044] FIG 3 shows a perspective view of a front of the pivot lever, as well as

[0045] FIG 4 shows a perspective view of the back of the pivot lever.

[0046] A component group 2 shown in FIG. 1 comprises a pivot lever, which forms a first component 4 and which is rotatably attached to a second component 6, which is in particular a side part of a seat support of a vehicle seat not shown in detail here. The component group 2 shown is a prefabricated, initially unpainted component group 2, which is painted as such. For this purpose, the initially unpainted side 10

[0047] Component group 2 is immersed in a cathodic dip coating bath (not shown in detail here). A large number of such component groups 2 are mounted together on a holding frame, with an electrically conductive connection to each component group 2 being formed via the holding frame. It is important to note that, due to the electrically conductive connection between the two components 4 and 6, described below, only one of these components 4 and 6 is conductively connected to the holding frame. This allows for a compact, space-saving arrangement of a large number of component groups 2 on the holding frame, enabling a high number of component groups 2 to be coated simultaneously in a small space.

[0048] To enable this, it is necessary that the additional component 4, 6, which is not electrically connected to the holding frame, is also kept at a sufficient voltage potential so that the charged lacquer particles contained in the dipping bath are reliably deposited on this additional component 4, 6 as well. Generally, the component group 2 is brought to the required voltage potential via the holding frame and the at least one contact point with the at least one component 4, 6.

[0049] As can be seen particularly in conjunction with FIG. 2, the two components 4 and 6 are pivotably mounted to one another about a rotational axis D, which extends in an axial direction A. The two components 4 and 6 are, in particular, sheet metal parts, specifically bent sheet metal parts. In the exemplary embodiment, the pivot lever (first component 4) is elongated and, in particular, curved.

[0050] For the pivotable attachment of the two components 4 to one another, the first component 4 has a bearing hole 8, which is hereinafter also referred to as the first bearing hole 8. The first bearing hole 8 accommodates a bearing bushing 10, which is hereinafter also referred to as the first bearing bushing 10.

[0051] The first bearing bushing 10 is formed by a casting process and cast directly onto the first component 4. It consists of plastic with conductive additives, in particular conductive fibers, for example carbon fibers, incorporated into it (see page 11). This gives it a certain degree of electrical conductivity. The first bearing bushing 10 has a bushing rim 12 on each of the two opposite sides of the first component 8. This rim extends radially, i.e., perpendicular to the axial direction A, and each rim encompasses a hole rim of the first bearing hole 8, i.e., on a front side 14 and a rear side 16 of the first component 4. The two bushing rims 12 are connected to each other by a cast, and in particular cylindrical, bushing spacer. As can be seen particularly in the cross-sectional view of FIG. 2, each hole rim is encompassed by the first bearing bushing 10 in an approximately U-shaped manner.The first bearing bushing 10 is generally a monolithic, cast component.

[0052] The first component 4, with its rear side 16, rests in contact with a preferably planar wall region of the second component 6. In particular, the bushing edge 12 formed on the rear side 16 is sandwiched between the two components 4, 6 and forms a sliding surface.

[0053] The connection between the two components 4 and 6 is achieved by means of a bearing bolt 18, which is inserted through the first bearing bushing 8 and has a collar 20 formed by a widened bolt head, thus forming a locking head. The collar 20 rests on one of the two bushing edges 12. On the opposite side, the bearing bolt 18 has a further locking head 21, which, for example, is formed by a nut in the case of a screw bolt and, in the exemplary embodiment, by a rivet head produced by forming. In the exemplary embodiment, the bearing bolt 18 is therefore designed as a rivet bolt. The two components 4 and 6 are positively locked together by the bearing bolt 18 and the two locking heads, i.e., the collar 20 and the further locking head 21. In particular, they are preloaded against each other with a defined preload via the interposition of the bearing bushing 10.As can be seen in particular from FIG 2, page 12, the further locking head 21 lies directly against the second component 6, and is therefore clamped directly against this second component 6.

[0054] Overall, the first bearing bushing 10 forms an electrically conductive connection between the two components 4 and 6. This is due to the conductive additives incorporated into the plastic matrix of the first bearing bushing 10. Furthermore, it is essential that the first bearing bushing 10 is a cast component, thus establishing close and direct contact with the first component 4. Clamping via the bearing bolt 18 and pressing the collar 20 and the second component 6 against one of the bushing edges 12 each creates close contact with both the bearing bolt 18 and the second component 6.

[0055] As can be seen in particular in FIG. 3, the bushing edge 12 has protrusions 30 on at least one side, for example, only on one side or alternatively on both the front 14 and the back 16. In the exemplary embodiment, these are designed in the form of individual studs, which are arranged, in particular, evenly distributed around the first bearing hole 8. For example, at least six individual protrusions 30 and preferably between five and twenty protrusions 30 are arranged. These protrusions 30 each form a point contact with the collar 20, resulting in a higher (area) contact pressure. This increased contact pressure results in a higher contact resistance between the metallic collar 20 and the conductive plastic bushing, especially at these protrusions 30. This also contributes significantly to the conductive connection between the two components 4, 6.

[0056] As can be seen from FIGS. 1, 3, and 4, the first component 4 has a further bearing hole 22, which is hereinafter referred to as the second bearing hole. A further, second bearing bushing 24 is mounted in this hole, which is preferably identical to the first bearing bushing 10. A second bearing point is thus formed via this bushing, to which a third component, not shown in detail here, can be pivotably attached. Page 13

[0057] For example, the third component is a seat base of the vehicle seat, so that the seat support (second component 6) is pivotally attached to the seat base via the first component 4 (swivel lever), for example for height adjustment.

[0058] In the exemplary embodiment, the first bearing hole 8 is preferably associated with a further through-hole 26 in the first component 4, which is formed next to the first bearing hole 8 and which, in the exemplary embodiment, is smaller than the first bearing hole 8. The through-hole 26 is preferably non-circular. The first bearing bushing 10 preferably also penetrates this through-hole. The respective bushing edge 12 preferably forms a bushing flange 28 on both sides 14, 16, extending radially towards the through-hole 26. A hollow bushing spacer is again installed in the through-hole 26.

[0059] Preferably, such a through hole 26 is also assigned to the second bearing hole 22, and the second bearing bushing 24 is designed analogously and in particular identically to the first bearing bushing 10 with the bushing lugs 28.

[0060] The component group 2 described here, comprising the two components 4 and 6 connected via the conductive bearing bushing 10, is generally a component group specifically designed for a vehicle seat. For example, the bearing bushing 10 is attached to a tube / component for seat height adjustment, to a component for seat tilt adjustment, to a component for a leg rest or footrest, or to other pivotally movable component arrangements.

[0061] Page 14

[0062] Reference symbol list

[0063] 2 Component group

[0064] 4 first component

[0065] 6 second component

[0066] 8 first bearing hole

[0067] 10 first storage box

[0068] 12 Bushing edge

[0069] 14 Front

[0070] 16 Back

[0071] 18 bearing bolts

[0072] 20 collars

[0073] 21 Locking head

[0074] 22 second bearing hole

[0075] 24 second storage box

[0076] 26 through hole

[0077] 28 Bushing tab

[0078] 30 Survey

[0079] D axis of rotation

[0080] A Axial direction

Claims

Page 15 Claims 1. Component group (2) for a vehicle, in particular for a vehicle seat, comprising a first component (4) and a second component (6) rotatably attached to one another about a rotation axis (D) extending in an axial direction (A), wherein the first component (4) has a bearing hole (8) in which a bearing bushing (10) is cast, which is formed by partially overmolding the first component (4), and the two components (4, 6) are connected via a bearing bolt (18) guided through the bearing bushing (10), wherein the bearing bushing (10) is made of plastic with conductive additives contained therein, such that a conductive connection is formed between the two components (4, 6) via the bearing bushing (10) and the bearing bolt (18) guided therein, and wherein a layer of lacquer is applied to the component group (2).

2. Component group (2) according to the preceding claim, wherein the bearing bushing (10) has at least one radially extending bushing edge (12) with which the bearing bushing (10) engages a hole edge of the bearing bore (8) and wherein the bearing bolt (18) has a collar (20) with which it rests on the bushing edge (12).

3. Component group (2) according to one of the preceding claims, wherein the bearing bushing (10) surrounds the hole edge in axial direction (A) on both sides with a radially extending bushing edge (12).

4. Component group (2) according to one of the preceding claims, wherein in particular knob-like protrusions (30) are formed on the bushing edge (12) against which the collar (20) is pressed.

5. Component group (2) according to one of the preceding claims, wherein the bearing bushing (10) has a casting skin at least in areas where there is no contact with the bearing bolt (18).

6. Component group (2) according to one of the preceding claims, which is painted, wherein the bearing bushing (10) is free of paint. Page 16 7. Component group (2) according to one of the preceding claims, wherein the first component (4) has a further bearing hole (22) in which a further cast bearing bushing (10) is formed by partially overmolding the first component (4), wherein the further bearing bushing (10) is also made of plastic with conductive additives contained therein, wherein the further bearing bushing (10) is preferably free of paint.

8. Component group (2) according to one of the preceding claims, wherein the admixtures are conductive fibers, in particular carbon fibers.

9. Component group (2) according to one of the preceding claims, wherein the proportion of the impurities is in the range between 10 vol.% and 60 vol.% and in particular in the range between 10 vol.% and 40 vol.%.

10. Component group (2) according to one of the preceding claims, wherein the bearing bushing (10) is temperature resistant up to at least 150°C.

11. Component group (2) according to one of the preceding claims, wherein the first component (4) is a pivot lever and the second component (6) is a side part of a structure of a vehicle seat.

12. Method for painting a component group (2) of a vehicle, in particular a vehicle seat, in which an unpainted component group (2) is provided, comprising a first component (4) and a second component (6) rotatably mounted to one another about an axis of rotation extending in an axial direction, wherein the first component (4) has a bearing hole (8) in which a cast bearing bushing (10) is inserted, which is formed by partially overcasting the first component (4), and the two components (4, 6) are connected via a bearing bolt (18) guided through the bearing bushing (10), wherein the bearing bushing (10) is made of plastic with conductive additives contained therein, such that a conductive connection is formed between the two components (4, 6) via the bearing bushing (10) and the bearing bolt (18) guided therein, wherein to Page 17 Applying a layer of paint to the unpainted component group (2) by means of cathodic dip painting.

13. Method according to the preceding claim, wherein the unpainted component group (2) is electrically contacted only at one of the two components (4, 6) for the purpose of carrying out the cathodic dip coating.

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