Rotary knob and motor vehicle

Abstract

The invention relates to a rotary knob (1), wherein the rotary knob (1) has a disc (2) and a retaining rib (4) projecting from a first side (3) of the disc (2) for gripping and operating the rotary knob (1), wherein a shaft (8) projects perpendicularly from a second side (7) of the disc (2), which is connected to the disc (2) via a collar (9). Essential to the invention is that the rotary knob (1) is designed as a plastic injection-molded part, that the retaining rib (4) has a bent cavity (6) extending through it in the longitudinal direction (5), and that the collar (9) has ribs (10). This helps to avoid sink marks in particular.

Description

The present invention relates to a rotary knob with a disk and a retaining web projecting from a first side of the disk for operating the rotary knob, according to the preamble of claim 1.U.S. Pat. No. 4,295,246 A discloses a rotary knob of the generic type, having a disk and a retaining web projecting from a first side of the disk for operating the rotary knob. From a second side of the disk there projects perpendicularly a shank which is connected to the disk via a collar. The shaft has a circular cross-section with a flat side, via which torque transmission from the disk to the shaft is possible.US 2004 / 0 107 545 A1 discloses a rotary knob made of polymer.U.S. Pat. No. 2,283,905 A discloses a further rotary knob having a disk and a retaining web projecting from a first side of this disk. A torque transmission can be achieved via a shaft which reaches through the disk and engages in the retaining web, since the shaft has a flat side which interacts with an associated flat side in a complementary receptacle of the retaining web.Furthermore, DE 35 35 881 C2 shows a rotary knob with a disk, a retaining web projecting from a first side of the disk and a shaft perpendicular to a second side of the disk.A generic rotary knob is likewise known from DE 10 2010 009 993 A1.In modern motor vehicles, plastic parts are increasingly being used, which are designed in particular as plastic injection molded parts and are thus extremely flexible with regard to shape, color and an area of use. The great advantage of such plastic injection molded parts lies in particular in a cost-effective and at the same time high-quality production. Difficulties in producing such plastic injection molded parts of high quality, in particular with high surface quality, are what are known as sink marks, that is to say defects on the surface of the plastic injection molded parts, which occur in particular at relatively thick sections and look like a depression or groove on the surface. The cause for this is an increased cooling time in thicker regions and a cooling time, in contrast thereto, shorter in the outer region of the plastic injection molded part. The use of an incorrect temperature during the injection molding of plastic can also lead to such sink marks on the surface of the finished plastic injection molded part. Furthermore, too low holding times and also a defective pressure distribution can be reasons which may possibly lead to such sink points. Such sink marks represent visual adverse effects, which, however, are perceived by a customer as unpleasant and in particular also as an indication of poor quality and should therefore be avoided.The present invention therefore addresses the problem of specifying an improved or at least one alternative embodiment for a rotary knob of the generic type, with which, in particular, such sink marks can be avoided, but at least reduced.This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject of the dependent claims.The present invention is based on the general idea of adapting a rotary knob designed as a plastic injection-molded part with respect to its shape at some points in such a way that sink marks, which can be perceived in particular as a visual impairment and also as an indication of a lack of quality, can be reliably avoided. The rotary knob according to the invention is designed as a plastic injection-molded part and has a disk and a retaining web projecting from a first side of this disk for operating, in particular for gripping and rotating, the rotary knob. The retaining web extends along the first side of the pane and furthermore has a kinked cavity running through it in the longitudinal direction, which cavity ensures a considerable weight saving and also contributes to saving resources. A shaft projects from a second side of the disk, which is connected to the disk in a rotationally fixed manner via a collar. This collar has ribs. The kinked cavity in the retaining web according to the invention makes it possible to reliably prevent an incidence point on an outer side of the cavity, since a wall thickness in the region of the kink in the kinked cavity can be designed as thin as in the surrounding regions, as a result of which a more rapid cooling or an equally rapid cooling takes place in this region as in the surrounding regions and incidence points at this point can be avoided. Due to the fact that the retaining web has an outer contour curved convexly upwards, i.e. an outer contour curved away from the pane, in this region, in the case of a cavity guided horizontally through the retaining web, i.e. parallel to the pane plane, a greater wall thickness would prevail in the middle of the retaining web, which would lead to a slower cooling and thus, if appropriate, to a sink point. By adapting the cavity to the outer contour of the retaining web, a substantially identical wall thickness can be achieved at preferably all points, whereby such sink points can be reliably avoided. In the case of a convexly curved surface of the retaining web, for example, two slides of a plastic injection molding tool arranged obliquely to one another are used here, which slides, in the retracted position, keep free the cavity which is kinked in the finished rotary knob. Here too, a reduction in material can be achieved by the ribs provided on the collar, as a result of which here too a homogenization of the cooling temperature can be achieved, which likewise contributes to reliably avoiding sink marks, i.e. optical defects.In an advantageous development of the rotary knob according to the invention, a kink in the kinked cavity is arranged centrally of the cavity. This makes it possible to equip the plastic injection molding tool with two substantially identical adjustable sliders which are retracted when the plastic injection molding tool is closed and thereby keep the kinked cavity free. The plastic is then injected into the cavity of the plastic injection molding tool and after a predetermined holding time the two slides are moved back and the plastic injection molding tool is opened, whereupon the rotary knob can be removed. By arranging the bend in the middle of the cavity, two identical sliders and preferably even two identical halves of the plastic injection molding tool can be used, which not only significantly simplifies and makes more cost-effective the production of the plastic injection molding tool, but also maintenance and repair of the same, if necessary.Expediently, the kinked cavity is kinked outwards, that is to say away from the pane. If the retaining web has a convexly shaped bulge upwards, the kinked cavity is kinked outwards in order to at least approximately follow the outer contour of the retaining web and thereby produce wall thicknesses of the retaining web which are substantially the same and thereby prevent the occurrence of so-called sink marks.In a further advantageous embodiment of the rotary knob according to the invention, the ribs extend parallel to the disk and perpendicular to the retaining web. By virtue of such an arrangement of the ribs, a comparatively simple demolding of the rotary knob, which is designed as a plastic injection-molded part, from a plastic injection-molding tool is possible, wherein the ribs, in addition, have a high rigidity by virtue of their shape and arrangement and, as a result, torques and also bending moments can be reliably transmitted from the disk and the retaining web to the shank.In a further advantageous embodiment of the solution according to the invention, the ribs extend perpendicular to the kinked cavity. The ribs can be realized, just like the cavity, by adjustable slides within the plastics injection moulding tool, wherein, by a perpendicular arrangement of the ribs to the kinked cavity, not only a stiffening of the pane but also a stiffening of the entire rotary knob is significantly improved, since the rotary knob is stiffened in one direction by the ribs and in the other direction by the kinked cavity or the retaining web running in the same direction.In a particularly preferred embodiment of the rotary knob according to the invention, its retaining web has a trapezoidal cross section. Such a trapezoidal cross section enables a clearly simplified gripping and thus a clearly simplified handling of the rotary knob by a user (m / w / d). Of course, the trapezoidal cross section of the retaining web can have rounded corner regions or edges, as a result of which pleasant haptics can be achieved when gripping the retaining web.In a further advantageous embodiment of the rotary knob according to the invention, the retaining web merges via rounded corner regions, i.e. grooves, into the first side of the pane. Such rounded corner regions, i.e. fillets, have a particularly favourable effect on what is known as a notch effect, which is significantly improved compared to angular corner regions. Such rounded corner regions can significantly reduce, in particular, local stress peaks.In a particularly preferred embodiment of the rotary knob according to the invention, the latter is formed as a one-piece plastic injection-molded part. By means of a corresponding embodiment of the plastic injection molding tool with corresponding slides, it is possible to design the entire rotary knob both with retaining web, disk, collar, ribs and shank as a one-piece plastic injection molded part, as a result of which it can be produced not only cost-effectively but also a subsequent assembly effort, in particular for mounting the shank on the disk or the retaining web, for example, can be dispensed with. It is purely theoretically conceivable that all the components of the rotary knob are formed from one and the same plastic, or that certain components of the rotary knob, such as the shaft, are formed from a plastic that is different from the retaining web, in order to produce both a high strength and a particularly pleasant haptics, for example.The present invention is further based on the general idea of equipping a motor vehicle with such a rotary knob according to the invention and thereby transferring the advantages described with respect to the rotary knob to the motor vehicle. Specifically, the advantages lie in an optically perfect appearance of the rotary knob and a reduced weight and also a reduced resource consumption, wherein in particular a reduced weight brings about a great advantage in motor vehicles, even on a small scale, on account of the energy saving to be achieved therewith during travel.Further important features and advantages of the invention are evident from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.It is understood that the features mentioned above and those still to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone, without departing from the scope of the invention as defined by the claims. The above-mentioned components of a superordinate unit, such as a device, a device or an arrangement, which are designated separately, and which will be mentioned below, can form separate components or components of this unit or can be integral regions or sections of this unit, even if this is illustrated differently in the drawing.A preferred exemplary embodiment of the invention is illustrated in the drawing and is explained in more detail in the following description.The single FIG. 1 shows a view of a rotary knob according to the invention.According to FIG. 1, a rotary knob 1 according to the invention and designed as a plastic injection-molded part has a disk 2 and a retaining web 4 protruding from a first side 3 of the disk 2 for gripping and operating the rotary knob 1. The retaining web 4 has a folded cavity 6 running through it in the longitudinal direction 5, a shank 8 protruding from a second side 7 of the disc 2 substantially in the vertical direction, which shank is connected to the disc 2 via a collar 9. This collar 9 has a plurality of ribs 10.The kinked cavity 6 according to the invention with a substantially centrally arranged kink 11 both in the underside and in the upper side of the kinked cavity 6 can ensure that a wall thickness of the retaining web 4 is preferably virtually the same thickness at all points in comparison with a non-kinked cavity, as a result of which undesired sink marks can be avoided, in particular in the case of a convexly curved surface or upper side of the retaining web 4. If the cavity 6 were not kinked, but were passed through the retaining web 4 in the longitudinal direction 5, the wall thickness would be thicker towards the top side in the middle than at the edge, as a result of which a so-called sink mark could occur at the outer side in the middle, which leads to an optical impairment which is equalized by a customer in particular also with a lack of quality.The ribs 10 arranged in the region of the collar 9 can also achieve here a thinning of the material, as a result of which a more rapid and in particular more uniform cooling of the rotary knob 1 according to the invention and designed as a plastic injection-molded part takes place in the region of the collar 9, so that here too no sink marks occur in the rotary knob 1 according to the invention, as could be the case, for example, in the case of a non-ribbed collar.If FIG. 1 is viewed in more detail, it can be seen that the kink 11 is arranged substantially centrally of the cavity 6, such that the kinked cavity 6 can be produced comparatively easily, for example by two adjustable slides in a plastics injection moulding tool. Due to the central arrangement of the bend 11, slides of equal length can additionally be used, whereby the diversity of parts is reduced and maintenance and repair outlay and also production outlay for such a plastic injection molding tool are reduced.The kinked cavity 6 is furthermore kinked outwards, here upwards, so that a wall thickness between the kinked cavity 6 and an upper outer surface 12 is preferably present at the same wall thickness overall.The ribs 10 extend parallel to the pane 2 along its second side 7 and furthermore perpendicular to the retaining web 4, wherein the ribs 10 extend perpendicular to the kinked cavity 6, which extends parallel to the retaining web 4.If FIG. 1 is further viewed, it can be seen that the retaining web 4 has a trapezoidal shape, in particular is thicker at the upper edge than in the connection region to the pane 2, as a result of which a significantly improved and facilitated gripping and thus also operation of the rotary knob 1 is made possible. Trapezoidal in this case means that the retaining web 4 is formed narrower on the first side 3 than at its free end. The retaining web 4 can furthermore transition via rounded corner regions 13 into the first side 3 of the pane 2, wherein notch stresses are reduced by such rounded corner regions 13 and the quality of the rotary knob 1 can thereby be increased.In general, the rotary knob 1 can be produced as a one-piece plastic injection-molded part, which is preferably produced even in a single plastic injection-molding process. This allows particularly cost-effective and high-quality production to be achieved. Alternatively, it is of course also conceivable for the shank 8 to be injection-molded from a different plastic than the retaining web 4 or the disk 2, wherein in this case the one part is injection-molded onto the other part. As a result, it is possible, for example, to use a different plastic for the retaining web 4 than for the shank 8, wherein the plastic for the retaining web 4 can be designed to be more grippable and haptically pleasant, for example.The rotary knob 1 according to the invention is used in a motor vehicle 14, in particular for example in the region of a cover for warning triangle and cast bag (trunk coverings).All in all, with the rotary knob 1 according to the invention with its kinked cavity 6, the occurrence of so-called sink marks can be avoided, but at least significantly reduced, whereby a significantly improved and at the same time a production which is significantly improved with regard to waste can be achieved.

Claims

Rotary knob (1), - wherein the rotary knob (1) has a disc (2) and a retaining web (4) protruding from a first side (3) of the disc (2) for gripping and operating the rotary knob (1), - wherein a shank (8) protrudes perpendicularly from a second side (7) of the disc (2), said shank being connected to the disc (2) via a collar (9), characterized - in that the rotary knob (1) is designed as a plastic injection-molded part, - in that the retaining web (4) has a kinked cavity (6) which extends through the latter in the longitudinal direction (5), - in that the collar (9) has ribs (10).Rotary knob according to Claim 1, characterized in that a bend (11) of the bent cavity (6) is arranged centrally of the bent cavity (6).Rotary knob according to claim 1 or 2, characterised in that the kinked cavity (6) is kinked away from the disc (2).Rotary knob according to one of the preceding claims, characterized in that the ribs (10) extend parallel to the disc (2) and perpendicular to the retaining web (4).Rotary knob according to one of the preceding claims, characterized in that the ribs (10) extend perpendicularly to the kinked cavity (6).Rotary knob according to one of the preceding claims, characterized in that the retaining web (4) has a trapezoidal cross section.Rotary knob according to one of the preceding claims, characterized in that the retaining web (4) merges via rounded corner regions (13) into the first side (3) of the pane (2).Rotary knob according to one of the preceding claims, characterized in that the rotary knob (1) is formed as a one-piece plastic injection-moulded part.Motor vehicle (14) having a rotary knob (1) according to one of the preceding claims.

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