You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
BACKGROUND 
     The invention relates to a closure for locking a cover on a structure that can be installed in the ground, and a cover designed accordingly. 
     For the drainage of surfaces, drainage channels are known, comprising a channel that can be installed in the ground and a cover attached to the channel, such that the drainage channel can be driven over. Further structures are point drainages or manholes, which likewise must be closed, such that they do not interfere with traffic. In any case, however, the important thing is that the attachment of the cover on the structure installed in the ground is secure. 
     On the other hand, it is important that the installation and the dismantling of the cover on the structure be very simple, because cleaning work is frequently necessary. 
     Closures for covers, or covers, respectively, are known from U.S. Pat. No. 3,201,161 or U.S. Pat. No. 1,693,190, comprising a latch, which is mounted on the cover and can move against the force of a spring, such that the snap bolt is forced back when closing the cover, and snaps in place in a closed position behind a counter bearing fixedly attached to the structure. 
     The known closures, and covers, respectively, however, have a very complex construction. Furthermore, the closures, and covers, respectively, are prone to corrosion, such that after a certain time in use, a proper functioning thereof is no longer ensured. 
     SUMMARY 
     The invention addresses the object of further developing a closure for locking a cover, and a cover having a closure of this type, respectively, such that, with a simple construction and a simple installation, a durable functionality is ensured. 
     This object is achieved by means of a closure described herein, and a corresponding cover, respectively. 
     This object is achieved, in particular, by means of a closure for locking a cover on a structure that can be installed in the ground, e.g. a drainage channel or a manhole, having a latch, which is designed such, and is movably mounted on the cover, against the force of a spring device, such that the snap bolt is forced back when closing the cover and snaps in place behind a counter bearing fixedly attached to the structure, wherein the latch is mounted in a housing, which can be secured in a housing receptacle in the cover. The object is also achieved by means of a cover having a closure of this type. 
     A substantial aspect of the invention is that the latch is no longer mounted directly in the cover and its components, but rather, a housing is provided, which, in turn, is secured in the cover. As a result, it is possible to create a closed unit, composed of a housing and the moving parts, in which the individual elements are coordinated to one another. This entire component can then, in turn, be attached to the cover. 
     It is possible for the housing of the latch to be open toward the bottom. As a result, the individual components of the latch, e.g. the snap bolt and compression spring, can be readily maintained or replaced. Furthermore, dirt that has infiltrated the housing falls out of the housing that is open toward the bottom, due to the gravity, when the grate is locked, and an impairment of the functioning of the latch due to contaminants in the housing is counteracted. 
     The housing receptacle is preferably designed as a recess in the edge of the cover, in which the housing is attached in the closed position, such that it cannot be released. The structure, i.e. the drainage channel or the manhole, which always has an edge (a frame) in structures of this type, simultaneously forms an element thereby, which secures the housing, and thus the latch in the cover. 
     The housing is preferably designed such that it is closed at its upper surface in the closed position. As a result, it is possible to keep substances compromising the function of the latch, any infiltration of dirt or the like, away from the latch. 
     The housing preferably has a retaining groove (or a retaining tongue), by means of which the housing can be fixed in a recess in the cover, which has a complementary retaining tongue (or retaining groove, respectively). The housing (and thus the latch) is thus secured in the cover in a form-fitting manner, with extremely little assembly effort. 
     The housing and/or the latch are preferably made of plastic. In particular, an injection molding procedure is suitable for this. As a result of this material selection, a simple production, on one hand, and a high corrosion resistance on the other hand, is ensured. 
     Furthermore, the housing is preferably designed such that it can be inserted in the recess in a direction of movement for the snap bolt. This means that in the closed position of the snap bolt, the housing can no longer be moved, and at the same time it is thus securely connected to the cover. 
     The housing preferably has a guide encompassing the latch. As a result, a securely functioning bearing of the latch is ensured over time. 
     The snap bolt preferably has a stop, which limits its movement in the closing direction. The latch, together with the housing, is thus comparable to a mortise lock that can be installed in a door. 
     Lastly, the latch preferably comprises a clamping device, by means of which the spring device can be connected to the snap bolt. As a result, it is ensured that the assembly can be assembled in a particularly simple manner. 
     A further substantial aspect of a closure, or a cover, respectively, of the type illustrated here lies in the operability when opening the cover. In order to simplify this, it is proposed that the housing have an engagement recess in a front region, from which the snap bolt protrudes, such that the snap bolt can be slid back to an open position by means of a tool, e.g. a screwdriver, inserted through the engagement recess from above. This engagement recess thus also directly indicates to the user where the tool is to be applied. 
     The housing, furthermore, preferably has an engagement bevel on its underside, beneath the snap bolt, by means of which the cover can be lifted away from the structure using a tool, e.g. a screwdriver. Thus, using the same tool, on one hand the latch can be opened, and on the hand, the opening tool is then used for lifting the cover. 
     The counter bearing is preferably designed as a two-piece bearing, such that a tool, e.g. a screwdriver, can be inserted between the two parts of the counter bearing, in order to engage with the snap bolt. As a result, a targeted positioning of the tool can be very easily achieved. 
     Furthermore, a bevel is preferably formed under the counter bearing, such that a tool, e.g. a screwdriver, which is used for opening the latch, is displaced by means of this bevel in the opening direction, when it is applied to and in contact with the bevel. The tool is thus deflected by this bevel. 
     In the following description, a preferred embodiment of the invention shall be explained in greater detail, based on drawings. Therein: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective depiction of a drainage channel with a partially applied cover, 
         FIG. 2  shows a perspective view of the cover according to  FIG. 1 , diagonally from above, 
         FIG. 3  shows a perspective depiction of the cover according to  FIG. 1 , diagonally from below, 
         FIG. 4  shows a longitudinal section, cut through an embodiment of the closure, 
         FIG. 5  shows a view of the closure along the line V-V from  FIG. 4 , 
         FIG. 6  shows a cut along the line VI-VI from  FIG. 5 , 
         FIG. 7  shows a perspective view of a closure, diagonally from above, 
         FIG. 8  shows a perspective view of the closure according to  FIG. 7 , diagonally from below, 
         FIG. 9  shows an exploded view of the closure according to  FIGS. 7 and 8 , 
         FIGS. 10A-10C  show a cross-section through a cover having a closure and drainage channels corresponding to the embodiment according to  FIG. 1 , in various assembled positions, and 
         FIGS. 11A-11C  show perspective partial sectional depictions corresponding to the assembled positions of the assembly according to  FIGS. 10A-10C . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the following description, the same reference numerals shall be used for components that are identical and have an identical function. 
     As is shown in  FIGS. 1-3 , a structure that can be installed in the ground—in this case, as exemplified by a drainage channel—comprises a structure  10  having a channel body  11 , the upper edge of which is formed by frames  12  in the known manner. A cover  20  is placed with the underside of its bearing surface  24  on the drainage channel  10 , or between the frames encompassing it at the sides. The cover  20 , in the exemplary embodiment of a drainage channel shown here, comprises channel ribs  21 , between which slots  22  are formed, such that surface water can flow into the channel. 
     Both frames  12  of the structure  10  have an identical design. On one hand, they have lugs  13  at regular intervals, which protrude inward, and on the other hand, latch counter bearings  14 ,  14 ′ are disposed between these lugs  13 , which are formed as “twins” and which have a tool passage  16  between one another. A bevel  15  is provided beneath the tool passage  16 , which, when a tool, e.g. a screwdriver, is inserted in the tool passage  16 , then forces the front edge of the blade of the screwdriver toward the middle of the channel body  11 . 
     The cover  20 , in turn, has an asymmetrical design, and has notches  23  on one of its edges, into which the lugs  13 , or the counter bearings  14 ,  14 ′ fit. On one side of the cover, these notches  23  are closed by a transverse rib  27 . This is shown in  FIG. 3 . Notch ribs  27  of this type—as shown in  FIG. 2 —are not provided in the notches  23  on the opposite side of the cover. As a result, when placing the cover  20  on the structure  10 , it is possible to first hook the cover  20  in place, in an inclined position (relative to the longitudinal axis), with the notch ribs  27  underneath the lugs  13 , or the latch counter bearings  14 ,  14 ′, respectively, and then lower the cover  20  in place. As a result, the cover  20  is securely held on the corresponding frame  12 , or the channel body  11 , respectively, in the closed state by the lugs  13  and the latch counter bearing  14 ,  14 ′ on the one side. 
     On the side of the cover  20  opposite the notches  23  having notch ribs  27 , an enlarged recess  25  is provided opposite the central notch  23 , into which a housing  40  can be inserted (inward from the outside). The housing  40  has—as is illustrated, in particular, in  FIGS. 5 to 9 —retaining grooves  43  on its exterior. The retaining tongues  26  corresponding to the retaining grooves are disposed in the recess  25 . Thus, the housing  40  can be inserted into the recess  25  from the outer edge of the cover  20 . The dimensioning in this case is carried out, such that the housing  40 , once it has been inserted, is securely seated in a form-fitting and friction-locking manner in the cover  20 . The housing  40  has a closed surface  46 , while the underside of the housing has an insertion opening  45 . Furthermore, the housing has a recess  47  on its front surface, which faces outward in the inserted state. Furthermore, this front surface is opened by a guide  44 , on the lower edge of which an engagement bevel  48  is provided. 
     A latch  30 , having a lower bevel  31  and an upper retaining surface  32 , can be inserted in the interior of the housing  40 . A pin-shaped spring seat  34  is attached to its inner end, opposite the bevel  31  and the retaining surface  32 , beneath which a clamping tongue  35  is seated. A stop  36  is provided between the spring seat  34  and the bevel  31 , or retaining surface  32 , respectively, which broadens the latch  30  such that, although it can be inserted in the guide, with the bevel  31  and the retaining surface  32  protruding over the front surface of the housing into the recess  47 , it does not, however, extend out of this guide  44 . 
     A compression spring  33  can be placed on the spring seat  34  such that it is held in place on the pin-shaped spring seat  34  by the clamping tongue  35 —as is shown, in particular, in  FIG. 4 . The end of the compression spring  33  opposite the stop  36  can be placed in a spring seat  41  in the housing  40 , such that the position shown in  FIGS. 4, 6 and 8  is then achieved. In this position, the compression spring  33  thus pushes the snap bolt  30  outward, such that it protrudes from the housing  40 . 
     The placement and locking of a cover  20  on a structure  10  is described below based on  FIGS. 10A to 10C and 11A to 11C . 
     First, the cover  20  is placed at an angle on a frame  12 , at its side lying opposite the recess  25 , or the housing  40  with the latch  30 , respectively, such that the lugs  13 , or the latch counter bearing  14 ,  14 ′, respectively, engage(s) in the notches  23 , and the notch ribs  27  are positioned beneath the lugs  13 , or the latch counter bearing  14 ,  14 ′ ( FIG. 10A / FIG. 11A ). 
     When the cover  20  is then lowered, the bevel  31  engages with the likewise beveled upper surface of the latch counter bearing  14 ,  14 ′ ( FIG. 10B / FIG. 11B ), such that the snap bolt  30  is pushed back, against the force of the compression spring  33 . 
     Once the final position has been reached, i.e., the cover  20  rests on the corresponding frame  12 , the snap bolt  30  is forced outward by the compression spring  33 , such that the retaining surface  32  of the latch  30  engages with the underside of the latch counter bearing  14 ,  14 ′. Thus, the cover is then held securely on the frames  12  of the channel body  11 , or securely held on the structure, respectively. The cover  20  can no longer be lifted upward in this state, because, on one hand, the notch ribs  27  are locked in place beneath the lugs  13 , or beneath the latch counter bearing  14 ,  14 ′, respectively. On the other hand, the lifting of the cover at the opposite side is prevented by the engagement of the retaining surface  32  of the latch  30  with the underside of the latch counter bearing  14 ,  14 ′. 
     In order to lift the cover, a tool, e.g. a screwdriver, is inserted between the two latch counter bearings  14 ,  14 ′. The front surface of the blade of the screwdriver then engages with the bevel  15 , such that the screwdriver is forced toward the middle of the channel, as a result of which the screwdriver, in turn, pushes the snap bolt  30 , against the force of the compression spring  33 , into the housing  40 . As a result, the retaining surface  32  is disengaged from the latch counter bearing  14 ,  14 ′. At the same time, by tilting the tool (screwdriver), the tool blade can then become engaged with the engagement bevel  43 , by means of which the cover  20  can be lifted away from the frame  12 . Thus, with a single tool, the latch is opened and the cover is lifted. 
     LIST OF REFERENCE SYMBOLS 
     
         
         
           
               10  structure/drainage channel 
               11  channel body 
               12  frame 
               13  lug 
               14 ,  14 ′ latch counter bearing 
               15  bevel 
               16  tool passage 
               20  cover 
               21  rib 
               22  slot 
               23  notch 
               24  bearing surface 
               25  recess 
               26  retaining tongue 
               27  notch rib 
               30  latch (snap bolt) 
               31  bevel 
               32  retaining surface 
               33  compression spring 
               34  spring seat 
               35  clamping tongue 
               36  stop 
               40  housing 
               41  spring seat 
               42  lateral surface 
               43  retaining groove 
               44  guide 
               45  insertion opening 
               46  upper surface 
               47  recess 
               48  engagement bevel

Summary:
Coverings for structures which can be installed in the ground are known. In order to lock the covering on the structure, closures are known which comprise a snap bolt which is designed in such a way and is mounted movably on the covering ( 20 ) against the force of a spring device in such a way that, during closing of the covering ( 20 ), the snap bolt is forced back and snaps in behind a counterbearing ( 14, 14 ′) fixed to the structure in a closure position. To simplify the arrangement and also to improve durability, it is proposed that the snap bolt is mounted in a housing ( 40 ) which can be fastened in a housing receptacle of the covering ( 20 ).