Patent Application
20210180641
The invention relates to an arrangement for introducing a force from a fastening element into a plastic component. The invention furthermore relates to a method for producing the arrangement.
Generic arrangements with a force-limiting element or a compression limiter have long been known in the art.
US 2016/0356291 A1 discloses a compression limiter for limiting the compressive force exerted by a fastening element during fastening of a component to a body. Here, the compression limiter comprises a sleeve which is formed in a cylindrical form with openings at both ends and a diaphragm which is coupled to an inner surface of the sleeve. The membrane can be deformed between a first configuration, which defines a slot on the membrane with a width smaller than a diameter of the fastening element, and a second configuration. As a result of this, the slot is widened in accordance with the diameter of the fastening element so that the fastening element is held in the sleeve as a result of an elastic force exerted by the membrane.
In another embodiment U.S. Pat. No. 6,457,925 B1 discloses a force-limiting arrangement to minimize compressive forces of a bolt on a first workpiece which is fastened to a second workpiece. In this case, the force-limiting arrangement comprises a longitudinal sleeve which defines a longitudinal axis which extends between an engagement end of the first piece and an end for insertion of the bore. The end which is in engagement with the first piece has a flange which prevents the bolt from moving past, wherein the longitudinal sleeve has a retention portion with a defined inner diameter. A second portion extends through a bore in a second piece. The second piece has a defined inner diameter which is smaller than the inner diameter of the retention portion and a pressure stop surface which extends perpendicular to the longitudinal axis between the retention portion and the second portion. The force-limiting arrangement furthermore comprises a bolt holder which is accommodated in the longitudinal sleeve, wherein the bolt holder can receive the bolt to prevent the bolt from falling out of the longitudinal sleeve if the force-limiting arrangement is inserted into the first and second piece. The force-limiting arrangement furthermore comprises a knurled surface which extends around a portion of the second portion.
These known arrangements are complicated in terms of structure and use and often offer insufficient support of the arrangement or the fastening element.
The object of the invention is therefore to structurally and functionally improve a force-limiting device cited above and thereby overcome at least one of the above-mentioned disadvantages.
According to one aspect, the object is achieved by an arrangement configured to introduce a force from a fastening element into a plastic component, the arrangement including a force-limiting element that is embedded in the plastic component; wherein the fastening element is configured to fasten the plastic component at a body; wherein the fastening element is insertable through the force-limiting element, and wherein the plastic component includes a retention device which protrudes at least partially into an interior of the force-limiting element so that the fastening element that is inserted into the force-limiting element is retained in the force limiting element.
Advantageous embodiments are provided in the dependent claims and additional independent claims.
The improved arrangement has the advantage that the fastening element can be premounted and transported together with the plastic component by means of the retention device. The fastening element is advantageously pressed or screwed into the plastic component. The customer thus does not have to separately procure, store or mount any fastening elements. The mounting time when using the arrangement is also significantly reduced for the customer by means of the premounted fastening element. By virtue of the fact that the retention device projects into the interior of the force-limiting element, it also support the force-limiting means tight in the plastic component, and thus satisfies a dual function.
In this application, the term plastic component refers to any plastic element which is to be arranged on a body with the aid of a fastening element. For example, plastic holders produced by injection molding are attached with the aid of e.g. screws to rigid or unmovable bodies. In the automotive sector, this can be used, for example, in the case of actuators for camshaft adjusters. The holder of such actuators corresponds here to an injection-molded plastic element which is attached with a steel screw to a body in the form of a vehicle body or the engine block.
In one advantageous embodiment, the force-limiting element is embedded by means of injection molding into the plastic component. For injection molding, a material is liquefied or plasticized with an injection molding machine and injected into a mold, the injection mold, under pressure. The material subsequently returns to a solid state by cooling or a cross-linking reaction and can be removed from the injection mold as a finished part. In order to achieve a connection to the force-limiting element, this is also placed in the injection mold. As a result of the over molding, the connection between the generated plastic component and the force-limiting element are formed to be particularly solid and sealing. Since, in this case, an embedding of the force-limiting element and simultaneously a generation of the plastic component with the retention device are carried out, the over molding makes the production process of the arrangement particularly efficient and low-cost.
According to the invention, the force-limiting element can be formed in a sleeve-like manner. It can also have an oval, square or triangular shape.
According to one particularly advantageous embodiment, the force-limiting element has at least one first recess. This recess is, for example, formed as a slot, a hole or a groove. In principle, the recess can have any form which makes it possible for it to be cast around with the plastic component during connection. The force-limiting element is held in a particularly stable manner in the plastic component by means of the recess. The liquefied plastic can thus flow through the recess into the interior of the sleeve-like force-limiting element.
Here, the first recess is advantageously arranged on a first opening of the force-limiting element. The force-limiting element can thus be enclosed or flowed around by the liquefied plastic component at the first opening during injection molding without covering the bearing surface to the body to which the plastic component is to be fastened. The advantages thus are in a functionally expedient structure of the arrangement with a particularly stable seat of the force-limiting element in the plastic component. The recess is easy to produce as a result of its arrangement at the opening and, as a result of the size of the recess, the extent of the inflow of the liquefied plastic, together with further process parameters of injection molding, can be influenced.
Building on this, the force-limiting element advantageously has at least one second recess, wherein the second recess is arranged on a second opening of the force-limiting element. The first and second openings are advantageously arranged opposite one another. The force-limiting element can, as a result, be enclosed or flowed around on both sides or at both openings without covering the bearing surface for the body. The seat of the force-limiting element is, as a result, formed to be even more stable and an additional inflow opening is available for the liquefied plastic into the interior of the force-limiting element.
According to the invention, the fastening element is advantageously formed as a threaded fastener, for example a screw, a bolt or a shank. The threaded fastener is a commonplace fastening element which is easy to obtain and is therefore particularly well suited for use in the force-limiting device. The fastening element advantageously has a head and a shank, wherein an external thread which projects from the shank is formed in a portion of the shank spaced apart from the head. A fastening element which has such a structure and is inserted into the plastic component offers particularly good retention. This retention is brought about by an interaction of the retention device and the projecting external thread once the external thread has been pressed or screwed through the force-limiting element in which the retention device is arranged. The fastening element can thus not get lost. At the same time, the fastening element in this position can also be moved in directions which deviate from an axial and rotational direction. In short, the fastening element has play. This can be explained in particular with the shank portion between the head and projecting thread since the diameter in this shank portion is smaller than in the shank portion of the projecting thread. As a result of this, the fastening element can be introduced in a particularly easy and comfortable manner into a mounting opening of the body and/or be placed thereon.
According to a further advantageous embodiment, the retention device in the force-limiting element forms an inner diameter which is smaller than the outer diameter of the projecting external thread. As a result of this, loss or dropping off of the fastening means can be prevented insofar as the threaded portion of the shank is pressed or screwed through the force-limiting element including the inner diameter reduced by the retention device.
In one advantageous embodiment, an internal thread is formed or can be introduced in the retention device. In the case of a formed internal thread, a fastening element formed with an external thread, advantageously a screw, can be screwed into the plastic component. In this manner, the fastening element can be guided through the plastic component particularly conveniently and without the exertion of force. The internal thread can be introduced, for example, by means of the fastening element formed with the external thread upon initial screwing into the plastic component. Thus, no additional auxiliary tools, such as, for example, a thread cutter, are required in addition to a screwdriver potentially required to fasten the plastic component in order to introduce the internal thread. The two stated embodiments make premounting of the fastening element in the plastic component significantly easier. A subsequent introduction of the internal thread furthermore reduces the precision and tolerance requirements when producing the plastic component.
In a further advantageous embodiment, the retention device is formed in one piece with the plastic component. Formed in one piece means that several elements, here the plastic component and the retention device, are formed integrally in one piece or as one part. No further components are therefore required in addition to the plastic component according to the invention for a retention function. This has cost advantages in production in particular because the plastic component and the retention device do not have to be connected in a separate working step.
According to an additional embodiment, the retention device has retention elements which are formed to be placed on the shank. For example, the retention elements can be incorporated in any desired number and from any desired direction into the interior of the force-limiting element. For example, the retention elements can be formed in a tongue-like manner and the tongue tips can be formed to be placed on the fastening element.
The retention device can furthermore advantageously be placed on the fastening element in a sealing manner. Such a sealing function is particularly important if the body on which the plastic component is to be fastened is to be protected from moisture, pressure or other external influences. The retention device thus performs a triple function. It retains, as already mentioned, both the force-limiting element and the fastening means in the plastic component and protects the body from external influences.
According to a further aspect, the object is achieved by a method for producing an arrangement as claimed in any one of the preceding embodiments. The method has similar advantages to the arrangement according to the invention and comprises the steps: providing the force-limiting element, embedding the force-limiting element into the plastic component, and inserting the fastening element through the force-limiting element.
The improved method has the advantage that the fastening element can be premounted and transported together with the plastic component by means of the retention device. The fastening element is advantageously pressed or screwed into the plastic component. This significantly simplifies mounting for a user since no fastening elements have to be procured, stored or mounted separately. The mounting time when using the arrangement is also significantly reduced for the customer. The retention device are incorporated during injection molding of the plastic component in a working step, as a result of which production of the arrangement itself is greatly simplified. It is therefore not necessary to add further components in a further working step.
In one advantageous embodiment, the embedding is performed by injection molding with a liquefied plastic. As already mentioned, as a result of this, the connection between the generated plastic component and the force-limiting element is formed to be particularly solid and sealing.
In a further advantageous embodiment, in the case of embedding the force-limiting element into the plastic component, the retention device flows into the interior of the force-limiting element. This simplifies the arrangement of the retention device and makes production particularly efficient and precise. Simultaneous embedding of the force-limiting element and arrangement of the retention device contribute overall to the efficiency and cost advantages in the production of the arrangement.
According to an additional embodiment, a spacer inserted into the force-limiting element limits the inflow of the retention device during embedding into the plastic component. As a result of this, the penetration depth of the inflowing plastic into the interior of the force-limiting element can be precisely controlled. The quality of the arrangement and the reliability of the method are thus additionally increased.
Moreover, an internal thread is advantageously incorporated into the retention device during insertion. As already mentioned, the internal thread is advantageously incorporated by means of the fastening element formed with the external thread upon initial screwing into the plastic component. No additional auxiliary tools and/or working steps to incorporate the internal thread are thus required.
Further advantages of the invention are described in greater detail below on the basis of an advantageous embodiment with reference to the drawing figures, wherein:
The plastic component 4 has several retention devices 7 which are formed in one piece with plastic component 4 and arranged projecting into an interior 8 of force-limiting element 5. The force-limiting element 5 has a first sleeve opening 9 and a second sleeve opening 10, wherein first sleeve opening 9 is arranged on the upper side 2 and second sleeve opening 10 is arranged on the lower side 3 of force-limiting element 5. The sleeve-like force-limiting element 5 furthermore forms a first bearing surface 11 on the upper side 2 and a second bearing surface 12 on the lower side 3. Several first recesses 13 are formed in the first bearing surface 11 and several second recesses 14 are formed in the second bearing surface 12, In particular this involves three first recesses 13 and three second recesses 14 which are not all visible here as a result of the longitudinal sectional view. The plastic component 4 projects through the recesses 13, 14 and partially into an interior 8 of the force-limiting element 5. The plastic component 4 is connected in one piece to retention device 7 through first recesses 13 on first sleeve opening 9. The retention device 7 extends in the longitudinal direction only over a sub-portion of interior 8.
The fastening element 6, which is formed here as a threaded fastener, advantageously a screw, comprises on upper side 2, a head 15 from which a shank 16 extends in the direction towards the lower side 3. The shank 16 is sized in its diameter so that it still has some play in relation to retention device 7. Since the retention device 7 extends in the longitudinal direction only over a portion of an interior 8, this play is large enough so that the fastening element 6 can be particularly easily incorporated into a body opening, not represented here, or placed thereon. The body opening is arranged on a body on which the plastic component 4 is to be mounted or fastened. Otherwise, in the case of a finished, mounted state of force-limiting device 1, the head 15 is placed on first bearing surface 11 and second bearing surface 12 is placed on the body. As a result of this, the force-limiting device 5 performs its function of improving an introduction of force caused by means of the fastening element 6 into plastic component 4 to be fastened to the body.
The fastening element 6 furthermore has an external thread 17 which is formed on a portion, spaced apart from the head 15 of the shank 16. The external thread 17 projects from the shank 16. Correspondingly the retention device 7 has a corresponding internal thread 18, not visible here. The internal thread 18 is incorporated into the retention device 7 for initial guiding or screwing in of fastening element 6.
As is apparent in
The plastic component 4 with the embedded force-limiting element 5 is represented in a top view in
As initially clearly visible in
The features described and shown in individual embodiments of the invention can be arranged in different combinations without departing from the spirit and scope of the invention. The scope of protection of the present invention is defined by the appended claims and is not restricted by the features described supra or shown in the drawing figures.
This application is a non provisional of U.S. provisional patent application 62/873,863 filed on Jul. 13, 2019 which is incorporated in its entirety by this reference.
