Injection molded component with integrated strain gauge and operating arrangement with such an injection molded component

Abstract

The invention relates to an injection-molded component (100) made of plastic material (K) with an electrical sensor for detecting deformations. The electrical sensor is a strain gauge (200) integrated into the injection-molded component (100) and completely embedded in the plastic material (K). The invention further relates to an operating arrangement comprising such an injection-molded component (100) and evaluation electronics configured to detect a deformation of the injection-molded component (100) as a switching movement using the strain gauge (200).

Description

The invention relates to an injection molded component made of plastic material, which is equipped with a sensor for detecting deformations. The invention further relates to an operating arrangement which comprises such an injection-molded component.The relevant injection-molded component is in particular a vehicle component, as explained in more detail below.WO 2024 / 110182 A1 describes a polymeric exterior attachment of a motor vehicle with at least one electrical sensor attached thereto. First, the shaping of the outer add-on part takes place by means of an injection molding process in an injection mold. The sensor is then mounted, wherein the sensor is fastened to the external attachment part in a positionally accurate manner with the aid of a receiving device.The object of the invention is to specify an injection-molded component of the type mentioned at the beginning which can be produced in a less complicated manner.The object is achieved by the injection-molded component according to the invention of claim 1. Advantageous refinements and refinements of the invention are obtained analogously for both subject matter of the invention from the dependent patent claims, the following description of the invention (this expressly also includes features described optionally and by way of example) and the figures.The injection-molded component according to the invention, by which an injection-molded or injection-molded plastic component is meant, is formed from an (injection-molded) plastic material, preferably a thermoplastic plastic material, and has one, i.e. at least one, electrical sensor. The electrical sensor is provided for detecting deformations, by which component deformations are meant. According to the invention, the electrical sensor is a strain gauge integrated into the injection-molded component and completely embedded into the plastic material, i.e. completely surrounded by the plastic material.Using the integrated strain gauge, deformations of the injection-molded component can be detected or detected and in particular also quantified. This allows component monitoring (for example load and / or damage monitoring, and also monitoring pressing forces if necessary) on the one hand and electrical switching operations to be implemented on the other hand, as will be explained in more detail below. That is to say that the at least one strain gauge integrated into the injection-molded component according to the invention can function as a measuring sensor and / or as a switch depending on the evaluation of the sensor signals (resistance change; see below).Strain gauges (DMS) as such are known in various embodiments from the prior art. Such a strain gauge is preferably formed from a flat carrier material, for example a carrier film, and at least one resistance wire or the like applied thereon. A deformation of the strain gauge leads to a change in the electrical resistance of the resistance wire, which can be registered and evaluated by means of suitable evaluation electronics. Reference is made below to corresponding technical literature.The injection-molded component according to the invention has at least one integrated strain gauge which is completely embedded in the plastic material and is provided primarily for detecting deformations. A strain gauge is comparatively inexpensive and works reliably even over a long period of several years. Furthermore, a strain gauge is very sensitive, so that even small component deformations of a few hundredths of a millimeter, which occur in the region of the strain gauge, can be detected. Due to the complete embedding in the plastic material, the strain gauge is on the one hand very well protected and on the other hand not visible from the outside (when using an opaque plastic material).The strain gauge can already be integrated into the injection-molded component or embedded into the plastic material during the injection-molding, i.e. molding, production of the injection-molded component, in particular directly during the injection-molding process. Various possibilities are described below. The injection-molded component according to the invention can therefore be produced with comparatively little outlay and is also suitable for series production, in particular for mass production.The injection-molded component according to the invention is preferably planar, in particular shell-like. Furthermore, it is preferably provided that this planar or shell-like component is designed for a bending load or for a bending movement resulting therefrom, at least for a local bending load or bending movement. In particular, it is then provided that the strain gauge is arranged outside the neutral fiber of the component, also referred to as a zero line.The strain gauge is preferably formed from a carrier film, in particular a plastic film, and at least one resistance wire applied thereon. The carrier film preferably has a higher melting temperature than the plastic material of the injection-molded component. The carrier film can be perforated, i.e. formed with holes, outside a measurement field formed by the resistance wire, wherein the holes are penetrated, in particular injection-molded, by the plastic material (of the injection-molded component). On the one hand, this enables a positive and thus particularly reliable force or movement transmission to the strain gauge. On the other hand, in the area of the strain gauge, the risk of detachment or delamination of the plastic material is reduced.The carrier film can also be pretreated, for example roughened, and / or coated, for example adhesive-coated, in order to improve the adhesion of the plastic material or the connection between the plastic material (of the injection-molded component) and the carrier film. The strain gauge may also have as a whole, i.e. including the resistance wire, a coating which acts as a heat protection and / or improves the adhesion of the plastic material.The strain gauge can have electrical connections which are designed, for example, as wires or as a conductor foil. It is preferably provided that the electrical connections are guided through the plastic material to a surface or outer side of the injection-molded component. In particular, it is provided that the electrical connections are, as it were, encapsulated by the plastic material or have been encapsulated by injection molding during the injection molding production of the injection molded component.It is preferably provided that the injection-molded component according to the invention is designed to be reversibly deformable, at least locally in the region of the strain gauge, preferably in such a way that it elastically deforms under a provided or expected load, in particular a bending load, and then resets again. With the aid of the integrated strain gauge, the reversible or elastic component deformation can be detected or detected and in particular also quantified. In particular, it is provided that the reversible or elastic component deformation is detected as a switching movement for effecting an electrical switching operation.The injection-molded component according to the invention is preferably a vehicle component, in particular a planar or shell-like vehicle component (see above). The injection-molded component according to the invention is in particular a pillar outer cladding for a side pillar (for example for the A, B or C pillar) of a vehicle body.As already mentioned, it is preferably provided that the at least one strain gauge is or has been integrated into the injection-molded component during the injection-molding production of the injection-molded component, in particular directly during the injection-molding process. The injection molding can be carried out, for example, in two substeps, wherein the strain gauge is positioned on the injection-molded part body after the first substep and is then quasi overmolded in the second substep. Alternatively, the strain gauge can be fixed in the cavity of the injection molding tool by means of needles which are then withdrawn during the injection molding or during the injection molding process. It is furthermore conceivable for the strain gauge to be positioned on a tool slide which can then be retracted during injection molding or during the injection molding process, so that the strain gauge is initially overmolded from one side and then from the other side. The method variants described can be automated very well and allow for a process-safe and positionally accurate embedding of the strain gauge in the injection-molded component.Due to the small thickness of the strain gauge, there is at most a small risk that an impression or a sink mark will form on the surface of the injection-molded component, which can then be located on the rear side of the injection-molded component, if necessary, by a suitable method procedure during production.An operating arrangement according to the invention comprises at least the following components:an injection-molded component embodied according to the invention; andan electronic evaluation unit which is designed to detect a deformation or a deformation of the injection-molded component, in particular an only local deformation of the injection-molded component, as a switching movement with the aid of or on the basis of the strain gauge, in order thereby in particular to bring about or trigger an electrical switching process, for example a door opening and / or door closing process, such that the at least one strain gauge integrated in the injection-molded component according to the invention functions as an (electrical) switch in a quasi-acting manner.Within the scope of the invention, both the features described above and those explained below can be used not only in the respectively specified feature combination, but also in other feature combinations or alone. This also applies to the features shown in the figures.The invention is explained in more detail below in a non-limiting manner on the basis of an exemplary embodiment shown in the figures. The features shown in the figures and / or explained below can also be general features of the invention, independently of specific feature combinations, and can correspondingly develop the invention. FIG. 1 shows an injection-molded component according to the invention. FIG. 2 shows the injection-molded component of FIG. 1 in a sectional view, according to the sectional profile A-A indicated in FIG. 1. FIG. 3 shows an embodiment of the strain gauge integrated in the injection molded component of FIGS. 1 and 2.The injection-molded component 100 shown in FIG. 1 is designed in the manner of a shell, i.e. flat and thin, and is manufactured in one piece from a plastic material K by means of injection molding, i.e. manufactured in one piece. The injection-molded component 100 is, for example, a pillar outer cladding, also referred to as a door pillar trim, for the B-pillar of a vehicle body, the invention being expressly not restricted thereto. The injection-molded component 100 is formed with an operating point B for actuating a door opener. The injection molding component 100 can also be formed with a plurality of such operator control points.The injection-molded component 100 has at least one strain gauge 200 integrated in the region of the operating point B and completely embedded in the plastic material K, i.e. completely surrounded by the plastic material K, as shown in FIG. 2. The strain gauge 200 is located virtually in the interior of the injection-molded component 100. The electrical terminals 250 of the strain gauge 200 are led through the plastic material K to the back surface of the injection molded member 100. The electrical connections 250 are connected to an electronic evaluation unit.With the aid of the integrated strain gauge 200, a deformation of the injection-molded component 100 brought about at the operating point B by an operating force F can be detected in order then to bring about or trigger an electrical switching process, namely a door opening and / or door closing process, with the aid of the evaluation electronics. In other words, a deformation of the injection-molded component 100 at the operating point S is detected as a switching movement, wherein the detection can be implemented very sensitive. The injection-molded component 100 is designed for a bending load, namely for elastic bending deformation and recovery, at least in the region of the operating point B, wherein the strain gauge 200 is arranged outside the neutral fiber N. The strain gauge 200 may also be used for component monitoring as described above.FIG. 3 shows the strain gauge 200 before it is integrated into the injection-molded component 100. As described above, it is preferably provided that the strain gauge 200 is integrated directly into the injection-molded component 100 during the injection-molding or during the injection-molding production thereof. The strain gauge 200 is formed from a carrier foil 210 and a resistance wire 220 applied thereon with a meandering course. For the above-described application, the strain gauge 200 can be designed to be approximately thumb-sized.Outside the measurement field 230 formed by the resistance wire 220, the carrier film 210 is perforated, i.e. is formed with a plurality of holes 240 which can be injection-molded with the plastic material K during the injection-molding production of the injection-molded component 100. The strain gauge 200 is pre-wired and has electrical terminals 250 that are led to the back surface of the injection molded component 100 during the injection molding of the injection molded component 100, as shown in FIG. 2.Furthermore, the strain gauge 200 may have a coating which protects the strain gauge 200 from the action of heat or heat during injection molding (wherein temperatures of more than 200° C. may occur) and / or improves the adhesion of the plastic material K.Further features and possible embodiments of the invention are described above.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedWO 2024 / 110182 A1

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Claims

Injection-molded component (100) made of plastic material (K) with an electrical sensor for detecting deformations, characterized in that the electrical sensor is a strain gauge (200) integrated into the injection-molded component (100) and completely embedded into the plastic material (K).Injection-molded component (100) according to Claim 1, characterized in that the strain gauge (200) has been integrated into the injection-molded component (100) during the injection-molding production of the latter.Injection-molded component (100) according to one of the preceding claims, characterized in that this injection-molded component (100) is configured planar, in particular shell-like, and is designed for a bending load, wherein the strain gauge (200) is arranged outside the neutral fiber (N).Injection-molded component (100) according to one of the preceding claims, characterized in that the strain gauge (200) is formed from a carrier film (210) and a resistance wire (220) applied thereon.Injection-molded component (100) according to Claim 4, characterized in that the carrier film (210) is perforated outside a measurement field (230) formed by the resistance wire (220), and the holes (240) are penetrated by the plastic material (K).Injection-molded component (100) according to Claim 4 or 5, characterized in that the carrier film (210) is pretreated and / or coated in order to improve the adhesion of the plastic material (K).Injection-molded component (100) according to one of the preceding claims, characterized in that the strain gauge (200) has electrical connections (250) which are guided through the plastic material (K) to the surface of the injection-molded component (100).Injection-molded component (100) according to one of the preceding claims, characterized in that this injection-molded component (100) is reversibly deformable.Injection-molded component (100) according to one of the preceding claims, characterized in that this injection-molded component (100) is a vehicle component, in particular a pillar outer cladding.Operating arrangement, comprising: - an injection-molded component (100) according to one of the preceding claims; and - an electronic evaluation unit which is designed to detect a deformation of the injection-molded component (100) as a switching movement with the aid of the strain gauge (200).

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