Patent Application
20200206993
The present invention relates to an injection-molding method for manufacturing a half-shell of a liquid container for a motor vehicle, and to a liquid container for a motor vehicle.
A large number of operating fluids are carried in modern motor vehicles, each of which is accommodated in a liquid container for a motor vehicle. For example, plastic fuel tanks are used to store fuel for an internal combustion engine.
Such plastic fuel tanks should ideally be light, crash-proof, and low in emissions. With regard to emissions, the stricter legal limit values for the maximum permissible fuel evaporation emissions from hydrocarbons into the environment must be observed. This requires, in particular, that fuel leaks be avoided under all operating conditions, such as during fueling, including refueling ventilation, during operational ventilation, i.e., fuel outgassing when the temperature of a tank system rises, and that the diffusion of the hydrocarbons through the tank wall be minimized.
In order to keep the diffusion through the container wall low, fuel containers often have a multilayer wall structure that includes a diffusion barrier, adhesion promoter, and cover layers. A barrier layer is usually bordered on two sides by two adhesive layers, which, in turn, are each covered by a cover layer. This results in a five-layer wall structure, for example, with a barrier layer made of EVOH, two adhesion promoter layers made of LDPE, and two cover layers made of HDPE.
If such a liquid container is produced with a barrier layer using the injection-molding method, the barrier layer is broken through in the vicinity of injection-molded connection elements such as a filler neck, a breather pipe, or the like. By breaking through the barrier layer, permeation paths are formed in the vicinity of such connection elements along which increased emission occurs during operation of hydrocarbons that diffuse out.
Against this background, the invention is based on the technical problem of specifying an injection-molding method for manufacturing a half-shell of a liquid container for a motor vehicle and a liquid container for a motor vehicle that do not have the disadvantages mentioned above or at least to a lesser extent and, in particular, enable reduced diffusion-related emissions to be achieved.
According to a first aspect, the invention relates to an injection-molding method for manufacturing a half-shell of a liquid container for a motor vehicle, with the method steps:
Diffusion-related emissions can be reduced through incorporation of the barrier sleeve in the region of the connection element.
The connection element can be a adapter. The adapter can be designed to connect a hose or a pipe. The adapter can have a circumferential chamfer or a circumferential web as a holding element for fastening a hose. The adapter can have the circumferential profile of a fir tree for holding a hose. The adapter can have a circular bulge for holding a hose. Alternatively or in addition, at least one connection element can be provided that is intended for the passage of electrical lines.
According to another embodiment, the injection-molding method is characterized by the provision of a barrier sleeve in the cavity, with the method steps: inserting the barrier sleeve into a recess in order to shape the connection element; and/or pushing the barrier sleeve onto a mandrel of the injection-molding tool.
The barrier sleeve can thus be held in a form-fitting manner in an injection-molding tool, it being possible for a mandrel or a recess to be provided for the purpose of holding the barrier sleeve on a mold half of an injection-molding tool. In this way, the barrier sleeve can be reliably and accurately positioned in an injection-molding tool. The barrier sleeve can be held on the injection-molding tool by means of a vacuum or electrostatically.
According to another embodiment, the injection-molding method is characterized by the provision of the barrier film and the barrier sleeve in such a manner that a longitudinal axis of a through hole of the barrier sleeve is oriented transverse to an outer or inner surface of the barrier film and/or that the barrier film rests against the barrier sleeve.
In particular, the longitudinal axis of the through hole of the barrier sleeve can be oriented perpendicular to an outer surface or inner surface of the barrier film.
The barrier film can rest against the barrier sleeve in such a manner that the barrier film lies in a flush or overlapping manner against the barrier sleeve, particularly without a gap. The barrier sleeve thus complements the barrier effect of the barrier film in the vicinity of the connection element.
According to another embodiment, the injection-molding method is characterized by the provision of the barrier film and the barrier sleeve in such a manner that a through hole of the barrier film is flush with a through hole of the barrier sleeve at least in some portions and/or that a through hole of the barrier film and a through hole of the barrier sleeve are arranged so as to be coaxial.
For example, a barrier film can be provided that is perforated at one or more points—i.e., that has one or more through holes. A barrier sleeve of a connection element can be associated with each through hole of the barrier film in order to achieve a reduction in the diffusion-related emissions of a respective connection element.
According to another embodiment, the injection-molding method is characterized by the provision of the barrier film and the barrier sleeve in such a manner that the barrier sleeve is seated at least partially in a through hole of the barrier film. The barrier sleeve can be completely enclosed peripherally by the barrier film in the region of a partial length. The barrier film can bear against an outer lateral surface of the barrier sleeve, particularly without a gap.
According to another embodiment of the injection-molding method, the barrier sleeve and the barrier film are integrally connected. The integral connection can occur, for example, during the injection-molding method as a result of a pressure and a rise in temperature resulting from the injection of the plasticized injection-molding material. Alternatively, a provision can be made that the barrier sleeve has been integrally connected to the barrier film prior to injection of plasticized injection-molding material into the cavity.
The barrier sleeve and the barrier film can be integrally connected to one another at least in some portions in the region of an overlap. In particular, the barrier sleeve and the barrier film can be welded to one another or glued to one another at least in some portions. This enables the barrier effect to be improved in the region of a seam between the barrier film and the barrier sleeve.
Alternatively or in addition, the injection-molding material can be integrally connected to the barrier sleeve and/or the barrier film.
The barrier sleeve and the barrier film can be integrally connected to one another and also integrally connected to the injection-molding material. The connections can be established in a substantially simultaneous manner through the introduction of the plasticized injection-molding material into the injection-molding tool and the associated application of pressure and inputting of heat.
A provision can be made that the barrier sleeve is connected—particularly glued or welded—to the barrier film before it is introduced into an injection-molding tool.
According to a second aspect, the invention relates to a liquid container for a motor vehicle, with two interconnected half-shells that delimit a storage volume for holding a liquid, at least one of the half-shells having a barrier film as a diffusion barrier and a connection element, particularly a connecting piece, for connecting a hose or pipe, and at least one barrier sleeve being associated with the connection element that forms a diffusion barrier in the region of the connection element.
Diffusion-related emissions can be reduced through incorporation of the barrier sleeve in the region of the connection element. The barrier sleeve can be an integral part of a container wall of the half-shell and can, in particular, be integrally connected to a carrier material of the half-shell.
The barrier sleeve and/or the barrier film can be connected in similar fashion to a material of the half-shell. For example, the barrier sleeve and/or the barrier film can have cover layers made of HDPE that enclose a barrier layer, a cover layer being integrally connected to a carrier material of the half-shell that is made of HDPE.
Depending on the wall thickness and material, the barrier sleeve can be flexible or limp or have a stiff structure.
The barrier sleeve can be an inlay that is provided for insertion into a recess in an injection mold or for pushing onto a mandrel of an injection mold.
In particular, at least one half-shell can have been produced using a method according to the invention as described above.
The connection element can be a adapter. The adapter can be designed to connect a hose or a pipe. The adapter can have a circumferential chamfer or a circumferential web as a holding element for fastening a hose. The adapter can have the circumferential profile of a fir tree for holding a hose. The adapter can have a circular bulge for holding a hose or pipe. Alternatively or in addition, at least one connection element can be provided that is intended for the passage of electrical lines.
According to another embodiment of the liquid container, a provision is made that a longitudinal axis of a through hole of the sleeve is oriented transverse to an outer surface or inner surface of the barrier film.
In particular, the longitudinal axis of the through hole of the barrier sleeve can be oriented perpendicular to an outer surface or inner surface of the barrier film.
The barrier film can rest against the barrier sleeve in such a manner that the barrier film lies flush against the barrier sleeve, particularly without a gap. The barrier sleeve thus complements the barrier effect of the barrier film in the region of the connection element.
According to another embodiment of the liquid container, a provision is made that a through hole of the barrier film is arranged so as to be flush with a through hole of the barrier sleeve at least in some portions. Alternatively or in addition, a through hole of the barrier film and a through hole of the barrier sleeve can be arranged coaxially. Alternatively or in addition, the barrier sleeve can be seated in a through hole of the barrier film at least in some portions.
The barrier sleeve can be completely enclosed peripherally by the barrier film in the region of a partial length. The barrier film can bear against an outer lateral surface of the barrier sleeve, particularly without a gap.
The barrier sleeve and the barrier film can be integrally connected to one another at least in some portions. In particular, the barrier sleeve and the barrier film can be welded to one another or glued to one another at least in some portions. This enables the barrier effect to be improved in the region of a seam between the barrier film and the barrier sleeve.
According to another embodiment of the liquid container, a provision is made that the barrier film and/or the barrier sleeve is a monolayer, i.e., composed of a single layer. Alternatively or in addition, the barrier film and/or the barrier sleeve can be multilayered. Alternatively or in addition, the barrier film can be perforated.
The barrier film and/or the barrier sleeve can, for example, have a barrier layer made of EVOH (ethylene vinyl alcohol copolymer), two adhesion promoter layers made of LDPE (low-density polyethylene), and two cover layers made of HDPE (high-density polyethylene).
The injection-molding material can form a single-layer or multilayer carrier layer, which can have or consist of one or more of the following materials: Elastomer, thermoplastic elastomer, HDPE (high-density polyethylene), fiber-reinforced polyamide, PA (polyamide), partially aromatic polyamide, impact-resistant polyamide.
The single-layer or multilayer barrier layer can have or consist of one or more of the following materials: EVOH (ethylene vinyl alcohol copolymer), LDPE (low-density polyethylene), PEEK (polyether ether ketone), PA (polyamide), partially aromatic polyamide, HDPE (high-density polyethylene), fluoropolymer. For example, the barrier layer can be constructed in three layers from PA and EVOH, with a central EVOH layer being covered or bordered on two sides by PA cover layers. A six-layer wall structure, for example, or a five-layer structure made of HDPE, LDPE and EVOH can also be provided, in which case a central layer made of EVOH is covered on both sides by an LDPE layer, and the LDPE layers, in turn, are covered by HDPE layers.
For example, a barrier film can be provided that is perforated at one or more points—i.e., that has one or more through holes. A barrier sleeve of a connection element can be associated with each through hole of the barrier film in order to achieve a reduction in the diffusion-related emissions of a respective connection element.
According to another embodiment of the liquid container, a provision is made that a through hole of the connection element has a curved shape or has a bend, the connection element particularly forming a 45° connection, a 60° connection, or a 90° connection. The barrier sleeve can be adapted to the shape of the connection in order to provide a reliable barrier effect. A provision can be made for a connection with an inclination between 0° and 90°, it being possible for the inclination to be curved gradually as a freeform surface without forming a jump or bend.
According to another embodiment of the liquid container, a provision is made that the barrier film and the barrier sleeve are arranged so as to overlap at least in some portions, the barrier sleeve and/or the barrier film in particular having a flange or funnel shape at least in some portions. The overlap can reduce the emissions caused by diffusion in the region of a transition or a seam between the barrier film and the barrier sleeve.
According to another embodiment of the liquid container, a provision is made that the barrier film and the barrier sleeve are integrally connected to one another.
The barrier sleeve and the barrier film can be integrally connected to one another, particularly welded or glued to one another, for example in the region of an overlap.
Alternatively or in addition, the barrier sleeve and/or the barrier film can be connected integrally to an injection-molding material of the half-shell. Particularly, the injection-molding material can be a structuring carrier material to which the barrier film and/or the barrier sleeve are integrally connected. The barrier sleeve and/or the barrier film can thus be reliably incorporated into the liquid container so as to not be detachable in a destruction-free manner.
The barrier film and/or the barrier sleeve can have a wall thickness in a range from 100 μm to 1000 μm.
The half-shells of the liquid container can be integrally connected to one another, particularly welded to one another, along adjacent edges. A provision can be made that both half-shells have a barrier film with at least one barrier sleeve. A provision can be made that both half-shells have a barrier film but that only one half-shell has one or more connection elements with respectively associated barrier sleeves, while the other half-shell has no connection elements.
The barrier sleeve can be produced in one or more layers through extrusion of a hose material. This results in a seamless wall on the periphery with homogeneous component properties in terms of strength and barrier effect, for example. In order to achieve a multilayer structure, folded tubular films can be made available as raw material.
The barrier sleeve can be made from a single- or multilayer tape, film, or plate material that has been bent in the form of a sleeve and has been welded longitudinally along an abutting edge. In this case, the sleeve has a longitudinal seam.
A provision can be made that the ratio of a width or wall thickness b1 of the connection element in the region of a permeation path to a length L1 of the permeation path is less than or equal to 0.5 (b1/1L1<0.5).
In the following, the invention is described in further detail with reference to a drawing that illustrates exemplary embodiments:
If fuel is stored in the liquid container 3, there are increased diffusion-related fuel emissions along permeation paths 13. Fuel can diffuse out via the permeation paths 13, since plastic of the support layer 9 or the nozzle 1 is not confined from the surroundings U by the barrier layer 7 along these paths. As a result, hydrocarbon diffusion that is not limited by the barrier layer 7 occurs along the permeation paths 13 via the plastic of the carrier layer 9 and/or of the connection element 1, for example. The greater the number of connection elements 1 provided on a liquid container 3, the greater the fuel leaks due to diffusion-related hydrocarbon emissions or leakage into an environment U.
The liquid container 4 has two interconnected half-shells 6, 8. The half-shells 6, 8 define a storage volume 10 for receiving a liquid 12. Here, the liquid 12 is fuel 12 for an internal combustion engine of a motor vehicle. The half-shells 6, 8 each have a multilayer barrier film 14, 16 as a diffusion barrier.
In the present case, the half-shell 6 has three connection elements 2. It will readily be understood that the arrangement, number, and geometry of connection elements that are provided on the half-shells 6, 8 can be varied in accordance with an alternative exemplary embodiment. For instance, as an alternative or in addition to the arrangement shown in
In the present case, the connection elements 2 are connecting pieces 2 that are set up for connecting a hose 18, as exemplarily illustrated in
As can be seen in
The barrier sleeve 20 has a longitudinal axis L along which a through hole 24 extends, the through hole 24 being oriented transverse, in this case perpendicular, to an outer surface 26 and an inner surface 28 of the barrier film 14. The barrier sleeve 20 is seated in a through hole 30 of the barrier film 14, and the through hole 30 also extends along the longitudinal axis L and is thus arranged coaxially with the barrier sleeve 20.
The barrier film 14 and the barrier sleeve 20 have a multilayer construction in the present case. The barrier film 14 has a barrier layer 32 that is enclosed on two sides by cover layers 34. The barrier sleeve 20 has a barrier layer 36 that is enclosed on two sides by cover layers 38.
The barrier film 14 and the barrier sleeve 20 are integrally connected to one another—in the present case welded to one another. In the present case, the barrier sleeve 20 and the barrier film 14 are also integrally connected to an injection-molding material 40 of a structuring carrier layer 41 of the half-shell 6. The injection-molding material 40 is a thermoplastic—HDPE in the present case. The cover layers 34, 36 are also HDPE, which makes same-type welding possible.
In the present case, the barrier film 14 has a wall thickness d1 of approximately 700 μm. In the present case, the barrier sleeve 20 has a wall thickness d2 of approximately 500 μm.
According to alternative embodiments, a provision can be made that the barrier sleeve 20 and/or the barrier film 14 are embodied as monolayers, meaning that they are composed of a single layer. In this case, the monolayer is both used for the integral connection of the barrier layer to the carrier material 40 and also has the function of a diffusion barrier for the stored fuel 12, particularly for hydrocarbons.
The ratio of a width b1 or wall thickness b1 of the connection element 2 in the region of a permeation path 22 to a length L1 of the permeation path is less than 0.5 in the present case (b1/L1<0.5).
As can be seen from
By injecting injection-molding material 40 into an injection mold (not shown), the barrier sleeve 44 and the barrier layer 46 are welded to one another in an overlapping manner as a result of the pressure and temperature input, as can be seen in
The connection element 52 formed in this way thus has an inner barrier sleeve 44, the barrier film 46 also being arranged on the inside, i.e., so as to face toward a fuel to be stored.
The barrier film 58 is thus integrally connected to the carrier material 40 in the region of an inner side 60, while the connection element 54 is injection-molded locally on a side 62 facing away from the side 60. Like in the example of
In the present case, the barrier sleeve 66 has already been adapted to the resulting contour of the connection element 65 before the injection molding of the carrier material 40 and also has a flange 70 before the injection molding, in the vicinity of which the barrier sleeve 66 is integrally connected to the barrier film 68 as a result of the process of the injection molding of the initially plasticized carrier material 40. The barrier sleeve 66 and/or the barrier film 68 can be embodied as a monolayer or in multiple layers.
Depending on the hose, pipe, or cable to be connected, connection elements can have different types of profiles, as will be explained further below with reference to
According to
As will readily be understood, single- or multilayer barrier sleeves and single- or multilayer barrier films can be used in all of the variants discussed above.
The workflow of an injection-molding method according to the invention is described by way of example with reference to
A providing a barrier film in a cavity of an injection-molding tool, the cavity being provided for the purpose of shaping the half-shell;
B providing a barrier sleeve in the cavity;
C injecting plasticized injection-molding material into the cavity,
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2017 119 706.0 | Aug 2017 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/072927 | 8/24/2018 | WO | 00 |
