The air filter housing accommodates an air filter and is pro- vided with the necessary feed and discharge lines. Mounted on the edge, between the housing cover and the housing, is a rubber seal, which is preferably designed as a sealing ring in order to achieve a tight fit between the air filter housing and the hous- ing cover when the housing cover is in place.

It is familiar practice for securing the housing cover on the housing to use several clamps, screws, plastic clips or the like as connectors distributed around the circumference, in order to obtain a tight connection between the two components. The con- nectors have to be mounted individually in a time-consuming process during assembly. The clips or clamps, which are prefera- bly made of plastic, can snap off and may then have to be re- placed. Screws first have to be positioned and then screwed in using a tool. All these types of connectors can be dropped dur- ing assembly and have to be picked up, this not being possible without further ado in an automated process. In any case, sev- eral manual operations are necessary in order to implement the

circumferential fastening necessary for a tight connection. On the whole, assembly is very time-consuming when using any of the fastening methods familiar from the prior art. In addition, tools are necessary, which may also be dropped.

The object of the present invention to is facilitate and accel- erate the assembly of an air filter housing.

According to the invention, the object is solved in that the housing cover and the housing can be connected to one another by means of a locking frame which surrounds the housing cover and the housing in the region of the housing edge, said locking frame being positionable in closed position by means of transla- tory motion.

During final assembly of the air filter, the housing cover is placed on the seal of the housing edge and pressed down, so that the housing cover covers the entire edge of the housing. Axial force is then applied to displace the locking frame relative to the housing cover and the housing and move it into the closed position. In this position, the locking frame reaches around the housing and the housing cover in the manner of a clamp, pressing the two parts together in tightly sealing fashion.

The locking frame can be designed either as a closed profile, or as an open or slotted profile.

Due to the fact that the housing cover is not moved in relation to the housing during assembly, only the locking frame being moved relative to the stationary housing cover/housing, the sealing ring located in the housing edge is not subjected to any shearing forces that could result in displacement of the seal and thus in leaks. Consequently, the closing device according to the invention permits simple, two-handed assembly, without tools and without a need for any other connectors, such as screws, clips or hooks. In the same way, the housing cover can be de-

tached from the housing without tools. In the simplest case, only two components are necessary, namely the air filter housing and the unit comprising the locking frame/housing cover. Fi- nally, the closing device according to the invention permits greater freedom in terms of design and geometry, as no fastening elements or devices for this purpose have to be provided in the edge area.

If the locking frame is not designed as a closed profile, but is provided with a joint at one point, the locking frame can be of partially elastic design, allowing it to be bent open in order to simplify assembly.

Assembly is particularly facilitated if the locking frame is de- signed as a one-piece, closed profile and to be torsion- resistant. It has proven to be particularly expedient with this design that at least the edge of the housing cover can be con- nected to a side of the locking frame that is on top in in- stalled position, that the housing cover is mounted in a manner permitting relative movement in the locking frame and that a side of the locking frame that is on the bottom in installed po- sition can be placed on the housing edge and the locking frame connected to the housing by means of relative displacement. Dur- ing pre-assembly, this design makes it possible first to insert the housing cover into the locking frame in such a way that it is mounted in a manner permitting relative movement in the lock- ing frame. During final assembly of the air filter, the unit comprising the housing cover and the locking frame is placed on the housing edge, pressed down and fixed in place by displaying the locking frame in relation to the stationary housing/housing cover.

In order to prevent unintentional relative displacement of the locking frame from the closed position, snap-in elements can be provided between the housing cover and the locking frame and/or the locking frame and the housing, these elements engaging each

other or reaching behind each other when in locked position.

In a preferred configuration, one or more snap-in tabs are pro- vided on the housing cover, these having run-up bevels that ex- tend in the direction of thrust and snap-in cams that run essen- tially perpendicular to the direction of thrust and engage a snap-in recess provided on the locking frame when in closed po- sition.

The snap-in elements are customarily of elastic design, so as to achieve a more easily separable connection between the housing, the housing cover and the locking frame.

Like the air filter housing, the locking frame is preferably de- signed as an injection-moulded part, as plastics can be moulded easily and as required. Alternatively, the parts can be made of metal, or combinations of different materials can also be used.

The invention is described in the drawings on the basis of a preferred practical example. The figures show the following: Fig. 1 A perspective view of a locking frame according to the invention with inserted housing cover, Fig. 2 A perspective view of the locking frame, Fig. 3 A perspective view of the housing cover, Fig. 4 A perspective view of the air filter housing to which the housing cover can be fastened using the locking frame, Fig. 5 A top view of the locking frame and the housing cover as per Fig. 1, placed on an air filter housing, Fig. 6 A section along line VI-VI in Fig. 5 with the locking

frame in open position, Fig. 6a A section along line VI-VI in Fig. 5 with the locking frame in closed, assembled position, Fig. 7 A section along line VII-VII in Fig. 5, Fig. 8 A section along line VIII-VIII in Fig 5, and Fig. 9 A top view of the housing cover without locking frame.

Accordingly, the air filter housing consists of an essentially box-shaped housing 1 for accommodating an air filter not shown in detail. Housing 1 can be sealed in airtight fashion by hous- ing cover 2, which is placed on housing edge 3 and can be con- nected to housing 1 by means of locking frame 4 according to the invention.

According to Fig. 3, housing cover 2, which is designed as an injection moulded part, is provided with a dome-shaped arch with an all-round shoulder 5 at the bottom end in installed position.

In installed position, this shoulder 5 rests on housing edge 3.

The perimeter of shoulder 5 is provided with an integrally moulded housing cover web 6 extending downwards. This housing cover web 6 reaches over housing edge 3 when in installed posi- tion.

Figure 2 shows the structure of locking frame 4. Locking frame 4 is designed as a collar-like, closed profile frame reaching over shoulder 5 and housing cover web 6 with an upper section 7 that can be placed on shoulder 5 and from which an all-round locking frame web 8 extends downwards at an angle to upper section 7.

Upper section 7 is provided with a cut-out 9, through which the dome-shaped arch of housing cover 2 can pass.

During pre-assembly, locking frame 4 is placed onto housing

cover 2 from above, so that upper section 7 of locking frame 4 rests on shoulder 5 of housing cover 2. When locking frame 4 is pressed on, it snaps over housing cover 2, as described in more detail below. In installed position, housing cover 2 is mounted in locking frame 4 in sliding fashion, preferably over a range of 20 mm.

Outward-protruding projections 10, with recesses 10a between them, are provided at regular intervals on two opposite sides of housing cover web 6-referred to below as the longitudinal sides. These projections 10 have outward-protruding shoulders 10a at the upper end.

Provided below housing edge 3 on housing 1 is an outward- protruding, all-round rib 12, which is interrupted at regular intervals on the opposite longitudinal sides in order to form housing tabs 13 at recurring intervals. When housing cover 2 is in place, these housing tabs 13 are in alignment with projec- tions 10 on housing cover web 6 (see Fig. 6).

It can be seen from Fig. 7 that, in installed position, shoul- ders 10b rest in sliding fashion on a first, inward-protruding, all-round rib 15 of locking frame 4, which is integrally moulded on a leg 20 running vertically in installed position. This leg is of resilient design, in order to allow locking frame 4 to be snapped onto housing cover 2. Integrally moulded on leg 20 of locking frame 4, at a distance below the first rib 15 and space apart from each other, are several, inward-protruding frame tabs 16.

Figures 6 and 6a show how, when placing housing cover 2 on hous- ing edge 3, locking frame 4 is moved, by exerting axial thrust in the direction of arrow A, from the open position illustrated in Fig. 6 to the closed position shown in Fig. 6a, in which it reaches around the circumference of both housing cover 2 and housing 1.

After executing closing motion A, frame tabs 16 reach under housing tabs 13 under pre-tension, meaning that they are de- signed with an interference fit. Housing tabs 13 and frame tabs 16 are provided with run-up bevels of complementary design on their ends lying at the front in the direction of thrust, in or- der to allow them to move relative to each other without tilting and to realise the interference fit of housing cover 2 on hous- ing 1. As the frame tabs are provided around the entire circum- ference of locking frame 4, they also reach below all-round rib 12 of housing 1 on its lateral sides, there thus being a circum- ferential interference fit between housing 1 and housing cover 2 on up to three sides in closed position.

Figure 7 shows sealing ring 17, which is located between housing cover 2 and housing edge 3. It is held in place on housing edge 3 by means of a shoulder provided on the latter.

As can be seen by looking at Figs. 1,4,8 and 9, three tabs 18, spaced apart from each other, are integrally moulded on the rear end of housing cover 2. In order to fix the housing cover in place when housing cover 2 is placed on housing 1, these tabs 18 are inserted into correspondingly designed cut-outs 21, which are provided at appropriate points on a snap-in web 22 of the air filter housing that projects upwards beyond housing edge 3 and is offset slightly towards the outside.

The interaction of tabs 18 and snap-in recess 19 is illustrated in an enlarged view in Fig. 8, which shows a lateral cross- section along line VIII-VIII in Fig. 5. When locking frame 4 has been slid into closed position, projections 23, provided on the underside of snap-in recess 19, reach behind the upper end of the rear side of snap-in web 22. Projections 23 are integrally moulded on snap-in recess 19 in resilient fashion and can be raised via a projection 24, integrally moulded on the upper side of snap-in recess 19, in order to separate the snap-in connec-

tion between snap-in web 22 and downward-protruding projections 23. Preferably, two downward-protruding projections 23 and cor- responding upward-protruding projections 24 are provided, so that the snap-in connection can be separated with two hands.

The locking frame according to the invention permits simple as- sembly without tools. No clips, screws or hooks are needed that have to be positioned around the circumference between the hous- ing and the housing cover. The prior art required seven screws or retaining clips for fastening, meaning that the total number of parts has been reduced from a total of nine to two, namely the housing and the housing cover with the locking frame fitted on it. As no retaining clips are required around the circumfer- ence, the design of the housing and housing cover is more vari- able and can be better adapted to prevailing conditions.

List of reference numbers 1 Housing 2 Housing cover 3 Housing edge 4 Locking frame 5 Shoulder 6 Housing cover web 7 Upper section 8 Locking frame web 9 Cut-out 10 Projection lOa Cut-out lOb Shoulder 12 Rib 13 Housing tab 15 First rib 16 Frame tab 17 Sealing ring 18 Snap-in tab 19 Snap-in recess 20 Leg 21 Cut-out 22 Snap-in web 23 Projection 24 Projection