EP3030778B1 - Fresh air system - Google Patents

Description

The present invention relates to a fresh air system for an internal combustion engine.

To supply combustion chambers of an internal combustion engine, the internal combustion engine is equipped with a fresh air system. Such a fresh air system extends in the usual way from an inlet section, via which the fresh air from an environment enters the fresh air system, to an outlet section, from which the fresh air is distributed to the individual combustion chambers of the internal combustion engine. Between the inlet section and the outlet section, different components of the fresh air system can be arranged. As a rule, at least one air filter is arranged between the inlet section and the outlet section, which has a filter element in a filter housing in order to filter the fresh air supplied to the internal combustion engine. Furthermore, in a fresh air plant, e.g. at least one silencer, an air mass meter, a charging device and a charge air cooler can be arranged.

In certain installation situations, in particular in vehicles, it is often desirable that on the one hand the inlet portion and on the other hand the filter housing are each firmly connected to a periphery of the internal combustion engine, whereby these components are arranged stationary, for example in an engine compartment of a vehicle. In any case, the inlet portion and the filter housing are arranged stationary relative to each other. Furthermore, it may be necessary for reasons of space, to connect the inlet portion via a connecting portion with a housing cover of the filter housing, which serves to close the filter housing and is removable for changing the filter element. In this case, to change the filter element before the connection be solved between the aforementioned connecting portion and the housing cover to remove the housing cover from the housing can. However, this is comparatively complicated because the inlet section, which is connected to the connecting section, is firmly connected to the periphery of the internal combustion engine in the installed state of the fresh air system. As a result, the structure of the fresh air system designed comparatively complex. Furthermore, this also makes changing a filter element comparatively complicated.

From the US Pat. No. 6,463,901 B1 a fresh air system is known which has a filter housing in which an air filter is arranged. The filter housing is closed by a housing cover, which is connected via an air hose to an inlet of the fresh air system.

The WO 2012/147729 A1 shows a fresh air system with a filter housing, in which an air filter is arranged. The filter housing is connected via a connecting portion with an inlet of the fresh air system.

The present invention is concerned with the problem of providing an improved embodiment for a fresh air system of the type described above, which is characterized in particular by a simplified handling when changing the filter element. Furthermore, an easily realizable construction is desired.

This problem is solved according to the invention by the subject matter of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea, the connecting portion, which serves to connect the inlet portion to the housing cover releasably arranged on the housing cover outlet side and movably arranged on the inlet side at the inlet portion so that it has sufficient adjustability relative to the filter housing to remove the housing cover from the filter housing to be able to. Due to the movable arrangement of the connecting section at the inlet section, the connection between connecting section and inlet section need not be loosened or separated in order to be able to remove the housing cover from the filter housing. This simplifies the handling of the fresh air system when changing a filter element.

Particularly advantageous is an embodiment in which the connecting portion is arranged around a pivot axis adjustable at the inlet portion. With the aid of such a pivot axis, a predetermined degree of freedom for the relative movement of the connecting portion relative to the inlet portion and thus relative to the filter housing is defined, which simplifies the handling of the fresh air system during filter replacement. Due to the defined pivot axis, a rotational movement about the pivot axis results for the connecting section, as a result of which the connecting section can be moved out of the mounting space required for removing the housing cover, as it were along a circular arc path. A rotational movement has the advantage over axial movement, for example, that the connecting portion and the inlet portion can be made relatively rigid, whereby they are relatively easy to produce. In a linear movement, in particular in a telescopic linear movement, however, relative movements within the connecting portion or the inlet portion are required, whereby the structures required for this purpose are relatively complex.

Particularly advantageous is an embodiment in which the connecting portion is on the one hand directly connected to the inlet portion and on the other hand directly to the housing cover, so that ultimately only a single component, namely the connecting portion is required to connect the inlet portion with the housing cover. This also results in an extreme simplification for the construction of the fresh air system.

According to the invention, the inlet section is connected via a plug connection with the connecting section, in which an inner part is inserted axially into an outer part. This simplifies the assembly between connecting portion and inlet portion. Between the inner part and the outer part, a radial gap is formed, in which a preferably circumferentially closed circumferential elastic compensation body is arranged. By specifically provided radial gap, a relative movement between the inner part and outer part is possible. The elastic compensation body serves on the one hand to prevent direct contact between the inner part and outer part, whereby the risk of disturbing noise can be reduced. On the other hand, the compensating body can fulfill a certain sealing function in order to avoid false air suction in the region of the plug connection. Preferably, the compensating body is therefore configured circumferentially closed in the circumferential direction. Due to the plug connection with a radial gap, a mobility between connecting section and inlet section is realized in the plug connection. By a suitable dimensioning of the radial gap, the mobility between connection section and inlet section within this plug connection can be sufficient to adjust the connection section relative to the filter housing so far that the housing cover can be removed from the filter housing. Thus, the adjustability according to the invention between the connecting portion and the inlet portion is realized via the radial play afflicted plug connection. In particular, within this connector also defines the aforementioned pivot axis between the connecting portion and the inlet portion.

According to an advantageous development, the compensation body may be a foam body. Such foam bodies, in particular made of plastic, are comparatively easy to produce and have a high permanent elasticity. At the same time a sufficient shape adaptation can be realized by the foam body, so that with the help of the foam body of the radial gap can be filled particularly easily, especially in the circumferential direction completely closed. The foam body can be open-pored or closed-pored. Furthermore, the foam body may be applied to an inner surface of the inner part or to an outer surface of the outer part. The connection between the foam body and the inner or outer surface may be formed for example by gluing or welding.

In another development, an axial overlap between the inner part and outer part can be at least as large as a diameter of the inner part. In this way, it is achieved that, even with comparatively large relative adjustments between the connecting section and inlet section, sufficient positioning within the plug connection between the connecting section and the inlet section is maintained.

According to another embodiment, the compensation body can protrude axially via the connector. By this measure, it is basically possible to use the compensation body outside the connector for an additional function. For example, the compensation body can support the inner part elastically on the periphery of the internal combustion engine. If the inner part is formed at the inlet section, can be about the protruding from the connector Area of the compensating body to achieve a support of the inlet portion proximal to the connector on the periphery of the internal combustion engine.

The connector defines according to the invention a flat cross section having a long diameter and transverse to a short diameter. In particular, by this measure, the aforementioned pivot axis can be particularly easily defined within the connector. Due to the flat cross section, the pivot axis necessarily extends parallel to the long diameter of the flat cross section of the connector. Thus, the spatial position of the pivot axis between connecting portion and inlet portion can be specified by the spatial orientation of the connector or its flat cross-section.

According to the invention, the connecting portion can be secured by means of a latching connection on the housing cover, which has a predetermined mounting direction. This means that the connecting portion must be mounted in this mounting direction on the housing cover, so that the latching connection locked in order to determine the connecting portion on the housing cover. Suitably, this mounting direction extends perpendicular to the pivot axis, so that the predetermined by the pivot axis movement of the connecting portion is at least on the outlet side of the connecting portion in the mounting direction. As a result, the assembly can be considerably simplified.

Since the connector has the aforementioned flat cross section, the mounting direction is substantially perpendicular to the long diameter of the flat cross section.

In another embodiment, the connecting portion at the inlet portion a first flat cross-section and the housing cover a second have flat cross section, which is rotated by about 90 ° relative to the first flat cross section. In other words, a first long diameter of the first flat cross-section is approximately perpendicular to a second long diameter of the second flat cross-section. While the first long diameter preferably extends parallel to the aforementioned pivot axis of the connecting portion, the second long diameter preferably extends parallel to the above-mentioned mounting direction.

In another embodiment, the connecting portion may be connected by means of a latching connection with the housing cover, which has at least one manually operable unlocking element for releasing the latching connection. With the help of such an unlocking element, the latching connection can be particularly easily solved manually to separate the connecting portion of the housing cover and remove the housing cover from the filter housing can. The Entsicherungselement can be formed according to an advantageous development directly to a locking element of the locking connection and in particular integrally formed thereon.

According to another embodiment, at least one positioning element may be formed on the connecting portion, which cooperates with at least one, complementary thereto, formed on the housing cover Gegenpositionierelement for positioning and / or for aligning the connecting portion. The cooperating elements cause when attaching the connecting portion on the housing cover a positive and thus automatic optimal alignment of the connecting portion relative to the housing cover, thereby simplifying the assembly considerably.

According to an advantageous development, the respective positioning element or the respective counterpositioning element can be wedge-shaped or ramp-shaped. Further, the respective positioning element and the respective Gegenpositionierelement are appropriately aligned so that they drive the connecting portion in a direction transverse to the mounting direction axial direction against the housing cover when mounting the connecting portion on the housing cover. In particular, a desired relative position between connection section and housing cover can thereby be produced particularly easily.

According to an expedient refinement, a latching element and optionally at least one releasing element can be integrated into at least one such positioning element or at least one such counterpositioning element. Thus, the functions of the positioning or alignment on the one hand and the latching and optionally the release on the other hand can be integrated into the same components of connecting portion and housing cover. Such a high functional density reduces manufacturing costs and simplifies handling.

In another advantageous embodiment, the connecting portion and / or the inlet portion may be assembled from two shell bodies, which are each made in one piece as injection molded parts. As a result, the connecting section or the inlet section can be produced particularly inexpensively.

According to another embodiment, a resonator may be arranged on the connection section. Such a resonator is characterized by a non-perfused resonance chamber. Such a resonator can be designed for targeted damping of certain frequencies or frequency ranges, for example, to reduce sound propagation through the fresh air system against the flow direction of the fresh air into the environment.

The integration of such a resonator in the connecting section gives the connecting section an additional function. At the same time the attachment of a resonator in the fresh air system is extremely simplified.

According to an advantageous development, the resonator can have a resonator housing which is formed integrally on the connection section and a separate resonator cover have, which is fixed to the resonator housing. This results in a particularly simple and thus inexpensive realizable structure.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Fig. 1

eine isometrische Ansicht eines Abschnitts einer Frischluftanlage,

Fig. 2

eine vergrößerte Ansicht der Frischluftanlage im Bereich einer Verbindung zwischen einem Verbindungsabschnitt und einem Gehäusedeckel bei verschiedenen Zuständen a, b und c,

Fig. 3

eine isometrische Schnittansicht der Frischluftanlage im Bereich einer Verbindung zwischen dem Verbindungsabschnitt und einem Einlassabschnitt,

Fig. 4

eine isometrische Ansicht der Frischluftanlage im Bereich der Verbindung zwischen dem Verbindungsabschnitt und dem Gehäusedeckel bei einer anderen Ausführungsform,

Fig. 5

eine Ansicht wie in Fig. 4, jedoch in einer anderen Blickrichtung,

Fig. 6

eine isometrische Ansicht der Frischluftanlage wie in Fig. 1, jedoch bei einer anderen Ausführungsform,

Fig. 7

eine Ansicht der Frischluftanlage im Bereich einer Verbindung zwischen dem Verbindungsabschnitt und dem Gehäusedeckel, jedoch bei der in Fig. 6 gezeigten Ausführungsform,

Fig. 8

eine Ansicht wie in Fig. 7, jedoch in einer anderen Blickrichtung.

Show, in each case schematically,

Fig. 1

an isometric view of a section of a fresh air plant,

Fig. 2

an enlarged view of the fresh air system in the region of a connection between a connecting portion and a housing cover at different states a, b and c,

Fig. 3

an isometric sectional view of the fresh air system in the region of a connection between the connecting portion and an inlet portion,

Fig. 4

an isometric view of the fresh air system in the region of the connection between the connecting portion and the housing cover in another embodiment,

Fig. 5

a view like in Fig. 4 but in a different perspective,

Fig. 6

an isometric view of the fresh air plant as in Fig. 1 but in another embodiment,

Fig. 7

a view of the fresh air system in the region of a connection between the connecting portion and the housing cover, but in the in Fig. 6 shown embodiment,

Fig. 8

a view like in Fig. 7 but in a different direction.

According to the FIGS. 1 to 8 includes a fresh air system 1 shown here only partially, which serves in the assembled state for supplying combustion chambers of an internal combustion engine, not shown here with fresh air, an inlet section 2, an air filter 3 and a connecting section. 4

In the installed state, the inlet section 2 is fixedly connected to a periphery 5 of the internal combustion engine, which is indicated only symbolically here. Usually, the internal combustion engine is arranged in an engine compartment of a vehicle, so that the periphery can represent 5 connection points within this engine compartment. The inlet section 2 has an inlet opening 6, through which fresh air from an environment can enter into the fresh air system 1. The inlet opening 6 can basically open directly in this environment. It is also possible that the inlet opening 6 connects to a correspondingly shaped, not shown here air inlet.

The air filter 3 has a filter housing 7 shown here only hinted, which is also firmly connected to the periphery 5 in the installed state of the fresh air system 1. In the filter housing 7 a not shown here filter element is arranged, which is flowed through during operation of the fresh air system 1 of the fresh air to clean the fresh air. The air filter 3 also has a housing cover 8, which serves to seal the filter housing 7, wherein the housing cover 8 is detachably mounted on the filter housing 7 in order to remove the housing cover 8 for changing the filter element from the filter housing 7. If, as here, a pot-shaped housing cover 8 is provided, the filter element can also be arranged in the housing cover 8. It is also possible that the filter element extends at least partially within the filter housing 7 and partially within the housing cover 8. In any case, the respective filter element is located in an enclosed by the filter housing 7 and the housing cover 8 interior, so that for changing the filter element of the housing cover 8 must be removed from the filter housing 7.

The connecting portion 4 is used for fluidically connecting the inlet portion 2 with the air filter 3, wherein the connecting portion 4 is movably connected on the inlet side with the inlet portion 2, while the outlet side is detachably connected to the housing cover 8. The connecting portion 4 is for changing the filter element from the housing cover 8 releasably and relative to the filter housing 7 so far adjustable that the housing cover 8 is removable from the filter housing 7. This adjustability of the connecting portion 4 is also given when the connecting portion 4 is connected to the inlet portion 2 and when the inlet portion 2 is fixedly connected to the periphery 5. An adjusting movement of the connecting portion 4 relative to the housing cover 8 is in FIG. 1 . 2b and 2c each indicated by an arrow and designated 9. Preference is given to a rotational adjustability of the connecting portion 4 relative to the inlet portion 2. The rotation of the connecting portion 4 takes place with respect to a rotation axis or pivot axis 10, the in Fig. 1 and 2c is entered and which passes through a connecting portion 11, in which the connecting portion 4 is movably connected to the inlet portion 2. Visible, the adjusting movement 9 extends perpendicular to the pivot axis 10 or tangentially along a circular path about the pivot axis 10th

The connection region 11 is preferably configured as a plug connection 12, so that the inlet section 2 is connected to the connection section 4 via the plug connection 12. In this connector 12 are in accordance with the FIGS. 1 and 3 an inner part 13 and an outer part 14 axially inserted into one another, wherein the axial direction with an in FIG. 3 is indicated longitudinal center axis 15 coincident, which is defined by the connecting portion 11 and by the connector 12. The inner part 13 is inserted axially into the outer part 14. In the preferred example shown here, the inner part 13 is a part of the inlet portion 2, while the outer part 14 is a part of the connecting portion 4. A reverse construction is also possible. With respect to the longitudinal central axis 15 is radially in between the inner part 13 and the outer part 14 a in FIG. 3 recognizable radial gap 16 formed by the inner part 13 and outer part 14 relative to each other in the radial direction, that are perpendicular to the longitudinal central axis 15 relative to each other are movable. In this radial gap 16, an elastic compensating body 17 is arranged, which in a related to the longitudinal central axis 15 circumferential direction 18, the in FIG. 3 is indicated by a double arrow, rotates, preferably closed. The balancing body 17 is preferably a foamed body 19. The foamed body 19 can be manufactured separately from the inlet section 2 and separately from the connecting section 4 and can be attached thereto in a suitable manner. For example, the foam body 19 on the inner part 13, ie on the inlet section. 2 be glued on. Likewise, it is basically possible to form the foam body 19 directly on the inner part 13 and / or on the outer part 14, namely to foam.

According to FIG. 3 For example, the inner part 13 and the outer part 14 have an axial overlap 20, indicated by a brace, which may for example be at least as large as a diameter of the inner part 13. By the isometric view of FIG. 3 can the smallest diameter of the inner part 13, which here has a flat cross section, do not recognize. According to FIG. 3 is here also provided that the compensation body 17 and the foam body 19 protrudes axially via the connector 12. Visible, the compensation body 17 extends at the in FIG. 3 shown embodiment parallel to the axial direction outside the connector 12 about twice as far as inside the connector 12th

The connector 12 defines a flat cross-section, which in particular FIG. 1 is removable. The flat cross-section has a long diameter not shown here, which extends parallel to the pivot axis 10, and a perpendicular thereto extending short diameter, which is also not shown. In particular, the spatial orientation of the pivot axis 10 can be defined by the flat cross-section, since this inevitably runs parallel to the long diameter.

The connecting portion 4 can according to the Figures 2 and 4 to 8 expediently be fixed by means of a latching connection 21 on the housing cover 8. This latching connection 21 has a mounting direction 22, which in the Figures 2 . 4 and 7 is indicated by an arrow and the direction of movement 9 is oriented opposite. The mounting direction 22 and the direction of movement 9 extend perpendicular to the long diameter of the flat cross section of Plug connection 12 or perpendicular to the pivot axis 10. Thus, the mounting direction 22 runs along a circular arc about the pivot axis 10 tangentially.

Furthermore, in particular FIG. 1 can be seen, the connecting portion 4 has on the inlet side, ie at the inlet portion 2 has a first flat cross-section which has a not registered here first long diameter, and the outlet side, so on the housing cover 8 has a second flat cross-section, which also has not drawn here second long diameter , The two flat cross sections are rotated by about 90 ° to each other. As a result, the first long diameter runs essentially parallel to the pivot axis 10, while the second long diameter runs essentially parallel to the mounting direction 22 or parallel to the direction of movement 9.

How the Figures 2 and 4 to 8 can also be seen, the connecting portion 4 may further comprise at least one manually actuatable Entsicherungselement 23, by means of which the latching connection 21 is releasable. The latching connection 21 comprises at least one latching element 24, which cooperates with a counter-latching element 25 complementary thereto for latching the connection section 4 to the housing cover 8. In the in the FIGS. 2a to 2c As shown, the latching element 24 is formed by an integrally formed on the connecting portion 4, resilient latching hook, which is also referred to as 24 below. The counter-latching element 25 is an integrally formed on the housing cover 8 abutment which defines a latching contour, which can engage behind the latching hook 24. The Entsicherungselement 23 is formed here by a manually operable portion of the latching hook 24, whereby the latching hook 24 can be manually moved out of the counter-latching element 25 so as to release the latching connection 21. In the in the FIGS. 4 and 5 Shown embodiment, the locking element 24 and the Entsicherungselement 23 also integrated into each other. Also in the in the FIGS. 6 to 8 In the embodiment shown, the arming element 23 is formed by an integral part of the latching element 24.

How the Figures 2 and 4 to 8 can also be seen, at least one positioning element 26 may be formed on the connecting portion 4, while at least one complementary Gegenpositionierelement 27 is formed on the housing cover 8. When mounting the connecting portion 4 on the housing cover 8, the respective positioning element 26 and the respective counterpositioning element 27 act to position and align the connecting portion 4 relative to the housing cover 8. In the preferred examples shown here, the positioning element 26 and the associated counterpositioning element 27 are wedge-shaped or ramp-shaped, wherein the wedge shape or ramp shape relates to the mounting direction 22. When mounting the connecting portion 4 on the housing cover 8, the respective positioning element 26 can now cooperate with the associated Gegenpositionierelement 27 so that they the connecting portion 4 transversely to the mounting direction 22, namely axially, ie parallel to a longitudinal center axis 28, in the connection between connecting portion 4 and Housing cover 8 is present, drive. In the in the FIGS. 2a to 2c In the embodiment shown, the respective positioning element 26 is arranged separately from the latching element 24 and separately from the releasing element 23 at the connecting section 4. The same applies to the in the FIGS. 6 to 8 shown embodiment. In contrast to that in the in the FIGS. 4 and 5 In the embodiment shown, such a positioning element 26 is integrated in the detent element 24 or in the arming element 23.

How, in particular FIG. 3 can be seen, the connecting portion 4 can be assembled from two shell body 4 'and 4 ". and 4 "are each integrally formed as injection molded parts, for example, they may be welded together or clipped together to form the connecting portion 4.

In the in the FIGS. 6 to 8 In the embodiment shown, a resonator 29 is arranged on the connecting section 4. The resonator 29 has a resonator housing 30, in which a resonance chamber is located and which is closed by a resonator cover 31. The resonance space is acoustically connected to the air-guiding interior of the connecting portion 4. The resonator housing 30 is here integrally formed on the connecting portion 4. On the other hand, the resonator cover 31 is designed as a separate component and attached to the resonator housing 30. In this case, a welded connection or a clip connection or an adhesive connection can be used.

As farther FIG. 3 According to an advantageous embodiment, the inlet section 2 can also be assembled from two shell bodies 2 'and 2 ", which are preferably produced in one piece as injection molded parts and attached to one another in a suitable manner. 2 "has a section with a closed cross section in the circumferential direction 18 and a section with an open in the circumferential direction 18 cross section. The two sections with the respective open cross section complement each other in the assembled state to a closed cross section, so that the assembled inlet section 2 has a continuous cross section from the inlet end to the outlet end. The one shell body 2 'comprises the section with closed cross-section on the inlet side, while the other shell body 2 "has the section with closed cross-section on the outlet side has complex spatial structure, in which the inlet region defines a different flow direction than the outlet region.

In the examples of Fig. 1 to 5 is a pure-side air outlet 32 of the air filter 3 on the housing cover 8 is formed.

The operation of the exhaust system presented here is representative of the FIGS. 2a to 2c be explained in more detail.

To change the filter element, the housing cover 8 must be removed from the filter housing 7. To be able to remove the housing cover 8 from the filter housing 7, the connecting section 4 must first be removed from the housing cover 8. FIG. 2a shows the assembled state, ie the initial state in which the connecting portion 4 is locked to the housing cover 8. By manual actuation of the arming element 23, the latching hook 24 can be pushed away perpendicular to the mounting direction 22 and parallel to the axial direction 28 from the housing cover 8, whereby the latching element 24 is released from the counter-latching element 25 and the connecting portion 4 against the mounting direction 22 in the direction of movement 9 relative to the housing cover. 8 is adjustable. FIG. 2b indicates a state in which the latching connection 21 is released. Subsequently, the connecting portion 4 according to Figure 2c Further, according to the direction of movement 9 are pivoted relative to the housing cover 8 about the pivot axis 10, and indeed so far until the housing cover 8 is removable from the filter housing 7. After replacing the filter element, the assembly is done in reverse order. First, the housing cover 8 is placed on the filter housing 7. Subsequently, the connecting portion 4 can again be pivoted about the pivot axis 10, whereby the connecting portion 4 on the outlet side moves in the mounting direction 22. The respective positioning element 26 effects in conjunction with the associated Gegenpositionierelement 27, the desired alignment and positioning between the connecting portion 4 and the housing cover 8. Upon reaching the end position of the respective locking element 24 locks with the associated counter-latching element 25 and secures the mounting position.

Claims (11)

1. A fresh air system for an internal combustion engine,

   - having an inlet section (2) for fixed connection to a periphery (5) of the internal combustion engine,

   - having an air filter (3), which has a filter element, a filter housing (7) for fixed connection to the periphery (5) of the internal combustion engine and a housing cover (8) for closing the filter housing (7), which housing cover can be removed from the filter housing (7) to change the filter element,

   - having a connecting section (4) for the fluid connection of the inlet section (2) to the air filter (3), which connecting section is movably connected to the inlet section (2) on the inlet side and is detachably connected to the housing cover (8) on the outlet side,

   - wherein, to change the filter element when the inlet section (2) is connected to the connecting section (4), the latter is detachable from the housing cover (8) and adjustable relative to the filter housing (7) to such an extent that the housing cover (8) can be removed from the filter housing (7),

   characterised in

   - that the inlet section (2) is connected to the connecting section (4) by means of a plug-in connection (12), in which an inner part (13) is inserted axially into an outer part (14), wherein a radial gap (16) is formed between inner part (13) and outer part (14), in which radial gap is arranged an elastic compensating body (17) that runs around in the circumferential direction (18),

   - that the plug-in connection (12) defines a flat cross section, which has a long diameter and, transversely thereto, a short diameter,

   - that the connecting section (12) can be fixed to the housing cover (8) by means of a locking connection (21), which has an assembly direction (22),

   - that the assembly direction (22) runs substantially perpendicular to the long diameter of the cross section of the plug-in connection (12) .
2. The fresh air system according to claim 1,
   characterised in that
   the compensating body (17) is a foam body (19).
3. The fresh air system according to claim 1 or 2,
   characterised in that
   an axial overlap (20) between inner part (13) and outer part (14) is at least as large as a diameter of the inner part (13).
4. The fresh air system according to any one of claims 1 to 3,
   characterised in that
   the compensating body (17) projects axially over the plug-in connection (12).
5. The fresh air system according to any one of claims 1 to 4,
   characterised in that
   the connecting section (4) has a first flat cross section on the inlet section (2) and a second flat cross section on the housing cover (8), which second flat cross section is rotated approximately 90° in relation to the first flat cross section.
6. The fresh air system according to any one of claims 1 to 5,
   characterised in that
   the connecting section (4) is connected to the housing cover (8) by means of a locking connection (21), which has at least one manually operated releasing element (23) for undoing the locking connection (21).
7. The fresh air system according to any one of claims 1 to 6,
   characterised in that
   at least one positioning element (26) is formed on the connecting section (4), which positioning element interacts with at least one complementary counter positioning element (27), which is formed on the housing cover (8), to position and/or align the connecting section (4) relative to the housing cover (8) .
8. The fresh air system according to claim 7,
   characterised in that
   the respective positioning element (26) and/or the respective counter positioning element (27) are wedge- or ramp-shaped and drive the connecting section (4) against the housing cover (8) in an axial direction running transversely to the assembly direction (22) when the connecting section (4) is mounted on the housing cover (8).
9. The fresh air system according to any one of claims 1 to 8,
   characterised in that
   the connecting section (4) is composed of two shell bodies (4', 4''), which are each produced in one piece as injection-moulded parts.
10. The fresh air system according to any one of claims 1 to 9,
    characterised in that
    a resonator (29) is arranged on the connecting section (4) .
11. The fresh air system according to claim 10,
    characterised in that
    the resonator (29) has a resonator housing (30), which is formed integrally on the connecting section (4), and a separate resonator cover (31), which is fastened to the resonator housing (30).

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