Screw for connecting a plastic element to a base element

Abstract

Screw (12) for connecting a plastic element (8) to a base element (6), wherein the screw (12) comprises a head (18), a shaft section (20) extending along a screw axis (X) to the head (18) and a threaded section (22) with a thread (24) for screwing the screw (12) to the base element (6), characterized in that the screw (12) comprises a thickening (26) arranged between the shaft section (20) and the threaded section (22) for securing the screw (12) to the plastic element (8) against loss, wherein the thickening (26) extends in a plane perpendicular to the screw axis (X).

Description

[0001] The invention relates to a screw for connecting a plastic element to a base element.

[0002] The invention also relates to a component with such a screw and an assembly.

[0003] Screws come in many different shapes and sizes for different applications. For example, different thread parameters, screw lengths, and screw thicknesses can be adapted to specific applications.

[0004] It is advantageous to secure the screw against loss or falling off a component. For example, locknuts are used for this purpose. Other examples, such as pre-assembling the screw before the actual screwing, include bushings connected to the screw in such a way that the screw cannot fall off the component connected to the bushing.

[0005] However, such solutions are often complex to assemble. They also often require a large number of components, which increases the complexity of the bolted connection with locking devices.

[0006] It is an object of the present invention to eliminate or at least reduce these disadvantages.

[0007] In particular, it is an object of the present invention to provide a screw that enables particularly simple assembly while simultaneously securing it against loss. Another object of the present invention is to provide a component and an assembly comprising such a screw.

[0008] According to the invention, this object is achieved by a screw for connecting a plastic element to a base element, wherein the screw comprises a head, a shaft section adjoining the head along a screw axis and a threaded section with a thread for screwing the screw to the base element.

[0009] The screw includes a thickened portion located between the shaft portion and the threaded portion to secure the screw to the plastic element to prevent it from becoming lost. The thickened portion extends in a plane perpendicular to the screw axis.

[0010] The screw allows for easy installation by securing the screw to the plastic element. The thickened portion between the shaft and the threaded portion secures the screw against loss or falling off the plastic element. The screw is thus held to the plastic element by the thickened portion without actually screwing it in.

[0011] This enables, for example, pre-assembly of the screw(s) on the plastic element and further handling of the plastic element together with the screw(s), such as transport as a pre-assembled unit of screw(s) and plastic element.

[0012] According to preferred embodiments, the screw according to the invention comprises one, several or all of the following features, in all technically possible combinations: - the screw has a maximum radius at the thickening that is greater than a maximum radius of the screw in the shank section and greater than a maximum radius of the screw in the thread section; - the maximum radius in the shaft section is smaller than the maximum radius in the thread section; - the screw has a first end with the head and a second end along the screw axis, wherein the screw is tapered in one end region towards the second end of the screw; - the screw has radii in the end area that shorten linearly over the screw axis; - the screw is made of a metal, preferably steel; - the thickening has a surface extending in a plane perpendicular to the screw axis, the surface facing the head of the screw; - the head of the screw has a main part arranged centrally to the screw axis and at least one tongue extending radially outwards from the main part, wherein the tongue has a contact surface for resting on the plastic element.

[0013] The invention further relates to a component comprising a plastic element with an opening and a screw as described above, wherein the plastic element has at least one projection on an edge of the opening, wherein the head of the screw is arranged on a first side of the at least one projection and the thickening of the screw is arranged on a second side of the projection, so that the screw is held captively on the plastic element.

[0014] The invention further relates to an assembly comprising a component as described above, wherein the assembly further comprises a base element made of a metal, wherein the screw is received in the opening of the plastic element and is screwed to the base element, so that the screw fastens the plastic element to the base element.

[0015] According to a preferred embodiment, the assembly is a disc brake for a commercial vehicle. In this case, the plastic element is, for example, a cover, preferably an adjuster cover, of the disc brake.

[0016] The present invention will be explained in more detail below using exemplary embodiments and with the aid of several figures. However, individual components shown can also be combined with one another in a modified manner, so the invention is not limited to the exemplary embodiments shown.

[0017] They show: Fig. 1 a schematic sectional view of a component with a plastic element and a screw according to the invention held thereon; Fig. 2 a schematic sectional view of an assembly comprising the component of the Fig. 1 and a base element to which the component is attached; Fig. 3 a schematic view in plan view of the plastic element of the Fig. 1.

[0018] An example in Fig. The assembly 2 illustrated in Figure 2 comprises a component 4 and a base element 6, wherein the base element 6 is preferably made of a metal. The assembly 2 is, for example, a disc brake for a commercial vehicle, and the base element 6 is preferably a brake caliper of the disc brake.

[0019] The component 4 comprises a plastic element 8 with at least one opening 10 and at least one screw 12 which is received in the opening of the plastic element 8.

[0020] In Fig. 1 shows an example of component 4 in a pre-assembled state. In this state, screw 12 is held captively on plastic element 8, particularly in opening 10. In particular, component 4 is not attached to base element 6 in this state; in particular, screw 12 is not screwed to base element 6. Preferably, screw 12 is in direct contact with plastic element 8; in particular, no bushing is arranged between screw 12 and plastic element 8.

[0021] The pre-assembled state enables, for example, transport of the component 4, ie the plastic element 8 together with the screw 12, before assembly on the base element.

[0022] In Fig. 2, component 4 is shown in a fully assembled state. In the fully assembled state, component 4 is attached to base element 6, so that component 4 and base element 6 form assembly 2. In this state, screw 12 is received in the opening of plastic element 8 and screwed to base element 6, so that screw 12 fastens plastic element 8 to base element 6.

[0023] For example, the plastic element 8 is a cover, preferably an adjuster cover, of the disc brake. The adjuster cover is designed to cover a synchronization chain (not shown) of the disc brake, which is connected to a wear adjuster of the disc brake. According to examples, the cover has a plurality of openings 10, for example, six openings, in each of which a screw 12 is arranged.

[0024] In the preassembled state, in the example of the disc brake, the cover, together with the captive screws 12 on the cover, forms component 4. The cover with the screws 12 can, for example, be transported for final assembly of the cover on a brake caliper of the disc brake, which in this example forms the base element 6. Final assembly includes, in particular, screwing the screws 12 onto the brake caliper so that the cover is secured to the brake caliper.

[0025] The plastic element 8 consists of a plastic, for example one of the following materials: PA66 / 6 GF35, PA6 GF50, PA6 GF60, PA6T6I GF50.

[0026] The plastic element 8 preferably has at least one projection 14, for example three projections 14, on an edge of the opening 10. As shown by way of example in Fig. 3, each projection 14 narrows a radius of the opening 10 over a certain circular section of the opening 10. Preferably, each projection 14 is elastically deformable by the screw 12 during assembly, so that when the screw 12 is mounted in the opening 10, the or each projection 14 is bent and then swings back at least partially into the starting position.

[0027] For example, each projection 14 has an insertion chamfer 16, which in particular simplifies insertion of the screw 12 into the opening 10. In particular, the screw 12 is centered relative to an axis of the opening by the insertion chamfer(s) 16 during insertion.

[0028] The opening 10 defines an opening axis, which in the example of Fig. 1 and Fig. 2 coincides with a screw axis X of the screw 12. The opening 10 is delimited by an inner wall 15, which is in particular rotationally symmetrical with respect to the opening axis. Preferably, the inner wall 15 is inclined, i.e., in particular, not parallel, to the opening axis. In particular, a radius of the opening 10 increases with increasing distance from the projections 14. This makes it possible, for example, to hold the screw 12 inclined in the opening 10 and / or to screw it to the base element 6 in order to compensate for manufacturing tolerances, such as offset screw holes in the base element 6.

[0029] The screw 12 connects the plastic element 8 to the base element 6 by being arranged in the opening 10 and screwed to the base element 6. This situation is exemplified in Fig. 2. Even without screwing to the base element 6, see for example Fig. 1, the screw 12 is designed to be held captive on the plastic element 8 thanks to its geometry. This allows, in particular, pre-assembly of the screw 12 on the plastic element 8, with the screw 12 then being held in the opening 10.

[0030] The screw 12 extends along the screw axis X from a first end 17 with a head 18 to a second end 19. Preferably, the screw is tapered in an end region 21 toward the second end 19. In particular, the screw 12 has radii in the end region 21 that shorten linearly along the screw axis X toward the second end 19. This enables, for example, easy insertion of the screw 12 into the opening 10.

[0031] The screw 12 comprises the head 18, a shaft portion 20 adjoining the head 18 along a screw axis X, and a threaded portion 22 with a thread 24 for screwing the screw 12 to the base element 6.

[0032] According to the invention, the screw 12 comprises a thickened portion 26 arranged between the shaft portion 20 and the threaded portion 22. The thickened portion 26 enables the screw 12 to be secured to the plastic element 8 against loss. The thickened portion 26 extends in a plane perpendicular to the screw axis X. The thickened portion 26 is preferably annular. In particular, the thickened portion 26 completely surrounds the screw 12 on an outer side of the screw 12 in the plane perpendicular to the screw axis X. In particular, the thickened portion 26 is rotationally symmetrical. Preferably, the thickened portion 26 is integrally formed on the screw.

[0033] Preferably, the screw 12 has a maximum radius R at the thickening 26 that is greater than a maximum radius or the constant radius of the screw 12 in the shaft portion 20 and greater than a maximum radius of the screw 12 in the threaded portion 22. Preferably, the radius in the shaft portion 20 is smaller than the maximum radius in the threaded portion 22.

[0034] The thickening 26 preferably has a surface 28 extending in a plane perpendicular to the screw axis X and facing the head 18 of the screw 12. The surface 28 is configured to come into contact with the or each projection 14 if the screw 12 moves relative to the plastic element 8. This also prevents the screw 12 from becoming lost from the plastic element 8.

[0035] The head 18 of the screw 12 comprises a main part 30 arranged centrally to the screw axis X and a tongue 32 extending radially outward from the main part 30. The main part 30 has, for example, a recess or profile for a tool for screwing the screw 12, such as an internal or external hexagon. The tongue 32 extends, for example, completely circumferentially around the main part 30. The tongue has, in particular, a contact surface 34 for resting on the plastic element 8.

[0036] The shaft portion 20 preferably has a constant radius and / or no thread.

[0037] For example, the screw 12 has an intermediate section between the thickening 26 and the thread 24 of the threaded portion 22, which has a smaller radius with respect to the screw axis X than the threaded portion 22 and than the screw 12 at the thickening 26. The intermediate section preferably forms a circumferential incision on the screw 12.

[0038] Preferably, the shaft portion 20, the threaded portion 22, apart from a pitch of the thread 24, and the thickening 26 are rotationally symmetrical.

[0039] The screw 12 is preferably made of a metal, preferably steel. The screw 12 is preferably formed in one piece, including the thickened portion 26. In particular, the entire screw 12 is made of a metal, for example, steel.

[0040] When held on the plastic element 8, for example in the pre-assembled state, the head 18 of the screw 12 is arranged on a first side of the or each projection 14 and the thickened portion 26 of the screw 12 is arranged on a second side of the projection 14, which is opposite the first side. As a result, the screw 12 is held captively on the plastic element 8. In particular, the screw 12 is movable relative to the plastic element 8, but the movement is limited by the head 18 of the screw 12, for example during a movement of the screw 12 downwards into Fig. 1, and limited by the thickening 26 of the screw 12, for example when the screw 12 moves upwards in Fig. 1.

[0041] According to other examples, the assembly 2 is a component of an electronic air conditioning system of a commercial vehicle. In this case, the base element 6 is preferably a housing of the component. The plastic element 8 is a cover for closing part of the housing of the component of the air conditioning system, wherein the cover is attached to the housing by means of the screw 12.

[0042] Thanks to the shaft section 20, in which the radius of the screw 12 is smaller than the radius of the screw in the threaded section 22, it is particularly possible to easily install the screw 12 in holes in the base element 6 that are offset from the opening 10, for example, due to manufacturing tolerances or inaccuracies. In this case, the screw 12 can be installed slightly angled without coming into contact with or damaging an inner wall of the plastic element 8. The inclined inner wall 15 also enables or simplifies this installation with offset holes in the base element 6. List of reference symbols 2 assembly 4 component 6 Basic element 8 plastic element 10 Opening 12 screw 14 lead 15 Interior wall 16 insertion chamfer 17 first end 18 heads 19 second end 20 shaft section 21 End area 22 threaded section 24 threads 26 Thickening 28 Surface 30 Main part 32 Tongue 34 contact surface X screw axis R radius

Claims

[1] Screw (12) for connecting a plastic element (8) to a base element (6), wherein the screw (12) comprises a head (18), a shaft section (20) adjoining the head (18) along a screw axis (X), and a threaded section (22) with a thread (24) for screwing the screw (12) to the base element (6), characterized by that the screw (12) comprises a thickening (26) arranged between the shaft section (20) and the threaded section (22) for securing the screw (12) to the plastic element (8) against loss, wherein the thickening (26) extends in a plane perpendicular to the screw axis (X). [2] Screw (12) according to claim 1, wherein the screw (12) has a maximum radius (R) at the thickening (26) which is greater than a maximum radius of the screw (12) in the shaft portion (20) and greater than a maximum radius of the screw (12) in the threaded portion (22). [3] Screw (12) according to claim 2, wherein the maximum radius in the shank portion (20) is smaller than the maximum radius in the threaded portion (22). [4] Screw (12) according to any one of the preceding claims, wherein the screw (12) has a first end (17) with the head (18) and a second end (19) along the screw axis (X), wherein the screw (12) is tapered in an end region (21) towards the second end (19) of the screw (12), wherein preferably the screw (12) has radii in the end region (21) which shorten linearly over the screw axis (X). [5] Screw (12) according to any one of the preceding claims, wherein the screw (12) is made of a metal, preferably steel. [6] Screw (12) according to any one of the preceding claims, wherein the thickening (26) has a surface (28) extending in a plane perpendicular to the screw axis (X), the surface (28) facing the head (18) of the screw (12). [7] Screw (12) according to any one of the preceding claims, wherein the head (18) of the screw (12) has a main part (30) arranged centrally to the screw axis (X) and at least one tongue (32) extending radially outwardly from the main part (30), the tongue (32) having a contact surface (34) for bearing on the plastic element (8). [8] Component (4) comprising a plastic element (8) with an opening (10) and a screw (12) according to any one of the preceding claims, wherein the plastic element (8) has at least one projection (14) on an edge of the opening (10), wherein the head (18) of the screw (12) is arranged on a first side of the at least one projection (14) and the thickened portion (26) of the screw (12) is arranged on a second side of the projection (26), so that the screw (12) is held captively on the plastic element (8). [9] Assembly (2) comprising a component (4) according to claim 8, wherein the assembly (2) further comprises a base element (6) made of a metal, wherein the screw (12) is received in the opening of the plastic element (8) and is screwed to the base element (6) so that the screw (12) fastens the plastic element (8) to the base element (6). [10] Assembly (2) according to claim 9, wherein the assembly (2) is a disc brake for a commercial vehicle, wherein the plastic element (8) is a cover, preferably an adjuster cover, of the disc brake.

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