This application claims priority in German Patent Application DE 10 2020 112 461.9 filed on May 7, 2020, which is incorporated by reference herein.

This invention concerns an air intake device with a variable-length intake duct for an internal combustion engine, comprising:A base duct component with a base duct extending along a virtual base duct path, configured for the passage of intake air along the base duct path through the base duct component, wherein the base duct path is conceived as passing centrally through the base duct,An extension duct component with an extension duct extending along a virtual extension duct path, configured for the passage of intake air along the extension duct path through the extension duct component, wherein the extension duct path is conceived as passing centrally through the extension duct,A guidance arrangement, which guides the extension duct component and the base duct component to relative movement between a first operating position and a second operating position, wherein in the first operating position the base duct and the extension duct form, in mutually prolonging abutment, a continuous common duct section extending along the base duct and the extension duct as part of the intake duct, and wherein in the second operating position the extension duct is arranged at a distance from the base duct, such that only the base duct forms part of the intake duct, andA first centering arrangement, which when the duct components approach the first operating position is configured to decrease a radial distance in relation to the base duct path between an end section of the base duct path facing towards the extension duct component and an end section of the extension duct path facing towards the base duct component.

BACKGROUND OF THE INVENTION

Such an air intake device is known from the publication DE 197 28 600 A1. It is used in order to modify the effective length of an air intake duct as a function of the rpm of an internal combustion engine designed to interact with the air intake device, by having an extension duct component attached to a base duct component or separating it from same. Usually, the effective length of the intake duct is decreased with increasing rpm of the internal combustion engine and increased with decreasing rpm.

In order to attach the extension duct component reliably to the base duct component of the air intake device known from DE 197 28 600 A1, the longitudinal ends of the duct components: extension duct component and base duct component that face each other, act when approaching each other as a centering device. The effective length of the centering device formed by the duct components themselves is short, such that the known duct components have to be guided towards each other highly accurately in order to ensure a correct first operating position of the extension duct component and base duct component. An incorrect relative position of the extension duct component and base duct component in the first operating position, deviating from the required position, is accompanied by disturbing noises during the air intake device's operation. Besides, the known duct components have to approach each other along a predetermined approach direction.

Since, moreover, the centering sections of the duct components not only center, but also have to conduct flowing air, the centering sections are designable only subject to compliance with constraints dictated by fluid mechanics and acoustics.

SUMMARY OF THE INVENTION

It is, therefore, the task of the present invention so to further develop the air intake device referred to at the beginning, that with a greater structural and kinematic degree of freedom of the duct components than in the state of the art it can be structured simply and offer reliably low-noise operation. This task is solved according to the invention by an air intake device referred to at the beginning, in which the first centering arrangement is configured as separate both from the base duct and from the extension duct.

Although the guidance arrangement can be configured for the guidance of a translational and/or rotational relative movement of the duct components, for reasons of a preferred low movement space requirement of a pivoting movement the guidance arrangement comprises preferentially a pivot bearing, in particular a radial bearing.

By envisaging the first centering arrangement as separate from the base duct and from the extension duct, the configuration of the first centering arrangement is not constrained by being subject to fluid mechanics and acoustic requirements. The effective length of the centering device along the relative movement route of the duct components can be increased, such that the guidance accuracy of the guidance arrangement no longer matters. As a result, a simply constructed quiet air intake device is realized.

The first and the later described second centering arrangement each define, in the first operating position, the position and the orientation of the base duct component relative to the extension duct component within predetermined tolerance parameters (e.g. positional tolerance and/or angular tolerance). In an especially preferential embodiment, the base duct component and/or the extension duct component is designed as an injection-molded component, wherein preferentially at least one section, a number of sections, or all sections in each case of the first and/or the later described second centering arrangement are configured integrally with the base duct component and/or the extension duct component.

Especially preferentially, for designing a compact air intake device, the first centering arrangement is arranged spatially between the guidance arrangement on the one hand and the base duct and the extension duct on the other, since due to lever effects a relatively small centering arrangement can act over a large range of the relative movement's route. Most notably in the preferential rotational relative movement of the duct components, in this way the centering arrangement has to extend only over a rotational movement angle common with the duct components, wherein due to the shorter distance to the guidance arrangement its dimension can turn out shorter than the relative movement route of the duct components.

In order to provide uniform support between the base duct and the extension duct, the air intake device preferentially comprises further a contact arrangement with a contact formation and a mating contact formation, wherein in the first operating position the abutment between the base duct and the extension duct is configured as an abutment of the contact formation against the mating contact formation, and wherein in the first operating position the contact formation and the mating contact formation are passed through by the common duct section. Here in particular the first centering arrangement is configured to be at a distance from the contact arrangement, such that there exists freedom of design to configure both the first centering arrangement and the contact arrangement each for its assigned purpose, while reducing their effect on each other.

In order further to increase the positional accuracy of the extension duct component relative to the base duct component in the first operating state, the contact arrangement can comprise a second centering arrangement configured as separate from the first centering arrangement, configured when the duct components approach the first operating position to decrease a radial distance in relation to the base duct path between the end section of the base duct path facing towards the extension duct component and the end section of the extension duct path facing towards the base duct component. The second centering arrangement, which preferentially is formed by end regions of the duct components that point towards each other, can exhibit a very short effective length due to the first centering arrangement already provided. Nevertheless, it can interact with first centering arrangement to increase the accuracy considerably when establishing the first operating position.

In order to decrease noise generation by air escaping undesirably between the base duct component and the extension duct component, the contact arrangement can comprise a gasket bearing surface configured at the contact formation and a gasket arranged at the mating contact formation, wherein in the first operating position the gasket bearing surface is in contact with the gasket. Due to the position of the duct components relative to each other which in the first operating position is defined by the first and optional second centering arrangement, the position of the gasket and the gasket bearing surface relative to each other is also defined, whereby an especially reliable tight abutment of the base duct against the extension duct is achieved.

The gasket can be protected against damage by the duct component not carrying the gasket, if the gasket is arranged at a distance from a longitudinal end located nearer to the gasket of the duct of the duct component carrying the gasket.

The gasket can be arranged to be well-secured against coming loose in a groove surrounding the common duct section in the first operating position. The groove consequently surrounds the duct path of the duct component carrying it and likewise a section of a virtual common duct path conceived as passing centrally through the common duct section. This safeguard against coming loose can be strengthened by having the groove exhibit at least one anchoring formation, in particular an anchoring projection protruding into the groove's volume and/or an anchoring recess enlarging the groove's volume. Thus, an anchoring projection can engage with the gasket and/or the gasket with an anchoring recess. The anchoring formation can be configured in relation to the duct of the duct component carrying the gasket as an overhang or recess extending in a radial direction or/and in a direction parallel to the course of the duct path associated with the duct, wherein preferentially one, several, or all anchoring formations of the at least one anchoring formation surround, in particular completely, the duct path associated with the duct.

Preferentially, at least one of the anchoring recesses penetrates through a surface bounding the groove, preferentially a groove bottom or a groove flank. In particular, at least one of the, a majority of, or all anchoring recesses can be configured as a passage aperture.

An especially reliable arrangement of the gasket at the mating contact formation can be achieved, if the gasket and the mating contact formation are manufactured in a two-component injection molding process. The material of the gasket exhibits preferentially a lower modulus of elasticity than the material of the mating contact formation.

The first centering device can maintain its function durably if the first and second operating positions are each end positions of the relative movement of the extension duct component and of the base duct component. Then the maximum relative movement route of the duct components is fixed over the whole service life of the air intake device.

The first centering arrangement can comprise a centering socket and a centering projection configured to engage with the centering socket, in particular a centering spike. The centering projection can engage with the centering socket over more than 15%, preferentially over more than 30%, more preferentially over more than 50%, especially preferentially over more than 75%, or over 100% of the relative movement route between the first and the second operating position, in order to achieve the longest possible effective lengths. In this way, the centering arrangement can also fulfil a guidance function during the approach of the two duct components towards each other. Consequently, the centering arrangement can be a combined centering and guidance arrangement. Then it exists in addition to the aforementioned guidance arrangement.

In an especially preferential embodiment, the aforementioned guidance arrangement and/or the centering and guidance arrangement is so configured that during a movement between the first and the second operating position, a movement path of a point of a duct component made of an extension duct component and base duct component considered to be moving lies in a movement surface inclined to the duct paths of the duct components, in particular a plane of movement. Preferentially, the movement surface is inclined to a tangent to the duct path of the respectively other component, considered to be non-moving, in the region of the duct opening facing towards the moving duct component, since the duct component considered to be moving docks to this duct opening so to speak on approaching the first operating position. Through a short relative movement between the extension duct component and the base duct component this makes it possible to separate the extension duct from the base duct efficiently in fluid mechanical terms, since in this way the base duct component and the extension duct component when moving away from the first operating position towards the second operating position can be shifted not only axially along the common duct path in the connecting region of the two ducts but also away from each other with a movement component orthogonally hereto. In the preferential case of a rotationally guiding guidance arrangement, the rotation axis defined by the guidance arrangement is preferentially inclined to the duct paths of the duct components, i.e. non-parallel and non-orthogonal.

When the duct components are in the first operating position, the air intake device is in a first operating state with a longer intake duct. When the duct components are in the second operating position, the air intake device is in a second operating state with a shorter intake duct.

These and other objects, aspects, features and advantages of the invention will become apparent to those skilled in the art upon a reading of the Detailed Description of the invention set forth below taken together with the drawings which will be described in the next section.

