Abstract:
The invention relates to a battery plug for closing battery cells. The plug is formed of an essentially cylindrical housing which is open at the bottom and which can be inserted into the opening of the cell. The housing has an upper opening which can be closed by a lid. The plug has a collector mechanism located in the area of this upper opening for receiving gases which have risen and condensed. The collector mechanism may consist of a labyrinth insert whose top is provided with holes and pins extending downwards from the top.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a plug for closing battery cells, having an essentially cylindrical housing which can be inserted into an opening of the cell, is open at the bottom and whose upper opening can be closed by a lid. 
     In batteries for motor vehicles the accumulator cells are closed by a plug which is screwed into the opening of the cell by means of a thread. A screw plug of this type is entirely adequate, since in these batteries the level of the liquid electrolyte need only be checked occasionally. In contrast, more powerful batteries (heavy-duty accumulators) must be checked and topped up at substantially shorter intervals. Accordingly for the more powerful batteries plugs of the design outlined above are used whose upper opening—the checking and top-up opening—can be closed by a lid. This facilitates checking of the level, which is required at short intervals. However, it is disadvantageous that high-capacity batteries must be topped up very frequently, depending on their operational purpose, in many cases even daily, in order to compensate for the loss of liquid in the cell. 
     SUMMARY OF THE INVENTION 
     The invention is based on the object of providing a battery plug of the specified generic type, which is designed in such a manner that the evaporating liquid rising out of the cell is caught by simple means and returned back into the cell, with the result that checking and topping up can be carried out at substantially longer intervals. 
     According to the invention, this object is achieved in the case of a plug of the specified design by a collecting element for receiving rising and condensed gases being arranged in the region of the upper opening of the housing . 
     Since this collecting element is provided in the upper region of the plug, where temperatures are lower than in the underlying zones, the condensing of the rising gas is assisted, so that the liquid can be collected here and passed back into the cell. 
     IN A PREFERRED EMBODIMENT 
     The collecting element has a multiplicity of pins which protrude downward from a cover of the collecting element. The plurality of pins provides a very large surface area for the condensation. The pins allow the condensed liquid to drip downward and returned into the cell. 
     It is particularly advantageous if the collecting element consists of a labyrinth insert which has a cover which is interspersed with holes and from which the pins downwardly flood. The labyrinth insert can be fastened to the inside of the lid with a snap fit or in another manner, or else can be of integral design with the lid. 
     It has proven particularly advantageous in practice if, with the lid closed, the labyrinth insert forms, with its lower edge, a seal with respect to the inner wall of the housing, and between its cover and the insert of the lid bounds a flat clearance space which is connected via lateral passage openings to an annular space between the labyrinth insert and the inner wall of the housing, which inner wall has a degassing opening. 
     In this embodiment, the rising gases which are produced during operation in the plug housing initially sweep past the pins, where the condensing liquid precipitates. The gases then pass through the holes in the cover into the flat clearance space, where condensing gas is once again retained. The gases, which are virtually completely dehumidified, then pass via the lateral passage openings into the annular space and can escape from there to the outside by way of the degassing opening. 
     Battery plugs of the described design, which are provided for manual topping up of liquid, generally have a holder which is tapered conically downward, is inserted from above into the opening of the housing and protrudes downward as a small holder of smaller diameter. In the fitted state of the plug the lower end of the smaller holder is not intended to stand on the accumulator plates, it is merely intended to facilitate the checking and topping up. The smaller holder, which protrudes downward from the bottom of the conically tapered holder, serves mainly as an indicating element for the necessary filling height. During a check it can easily be established whether the filling level lies at the height of the open bottom of the holder, from which the small holder of lower diameter protrudes downward. However, since the distance between the upper periphery of the accumulator plates and the opening of the cell differs in different types of battery, a multiplicity of holders have to be kept ready in order to accommadate these dimensional differences. 
     In order to solve this problem in the case of a battery plug according to the invention, provision is made for the holder to be held by its upper edge in the housing in a longitudinally adjustable manner. In this case, it is preferred to fix the holder by its upper edge in the housing in an infinitely adjustable manner by means of frictional engagement against the inner wall of the housing. Radially resilient barbs and latching studs, which ensure the frictional engagement between the holder and housing, can protrude from the upper edge of the holder. 
     It is therefore possible to keep a standard holder ready for all sizes of battery, the holder being pulled out as far as possible before the plug is inserted into the cell opening. During the subsequent insertion into the cell opening the small holder is supported with its lower end on the upper side of the plates of the cell and is displaced relative to the housing until the latter has been completely inserted into the opening of the cell lid. 
     Height compensation, which may be necessary due to thermal expansion of the accumulator plates during operation, is provided as a consequence of the frictional engagement between the housing wall and barbs. 
     In another embodiment of the invention, the inner wall of the housing has latching sockets lying axially one above another on one side, for the snap-action engagement of the latching studs. This makes it possible to establish predetermined, specified positions for the position of the holder, which positions are suitable for most commercially available designs. 
     In the invention it is possible to insert the holder, rotated through 180°, into the housing, so that in a first position the latching studs engage in the latching sockets, while in the second position rotated through 180°, the latching studs do not engage in the latching sockets and bear in a frictionally engaged manner against the inner wall of the housing in order for the holder to be infinitely adjusted. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims appended to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects obtained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a longitudinal section through a plug according to the invention; 
     FIG. 2 shows a side view of the housing of the plug; 
     FIG. 3 shows a view from below of the housing of FIG. 2; 
     FIG. 4 shows the view from below of half of the labyrinth insert; 
     FIG. 5 shows a section through the labyrinth insert; 
     FIG. 6 shows a plan view of the labyrinth insert of FIGS. 4 and 5; 
     FIG. 7 shows a longitudinal section through the holder; and 
     FIG. 8 shows a plan view of the holder of FIG.  7 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     FIGS. 1 to  3  show a plug  10  with an essentially cylindrical housing  12  which is produced from plastic having an open lower side  14 , while an upper opening  16  is closed by a lid  18 , which is likewise injection molded from plastic. The lid  18  is coupled pivotably to the upper edge  22  of the housing  12  by a hinge  20 . In the closed position shown in FIG. 1, an elastically flexible edge region  24  of the lid  18  engages with a snap fit over a notch  26  on the upper edge  22  of the housing  12 . 
     FIGS. 1 and 2 also show a degassing opening  28  incorporated into the upper edge  22  of the housing  12 , through which gases can escape from the battery cell, on whose opening the plug  10  is placed, to the outside. 
     In the central region of the housing  12  there is formed a circumferential flange  30  which rests on the cell opening in the fitted state of the plug  10 . Below the flange  30  two narrow sealing lips  32  are integrally formed on the outside of the cylindrical housing  12 , and in the lower region the housing  12  has four outwardly protruding beads  34  which grip the cell opening from behind at the lower edge in the installed state of the plug  10 . Longitudinal apertures  82  formed between the beads  34  ensure that the lower region of the housing  12  is elastically flexible in the radial direction. 
     According to the invention, a labyrinth insert  36 , which is illustrated in detail in FIGS. 4 to  6 , is provided in the region of the upper opening  16  of the housing  12 . This labyrinth insert  36 , which is likewise produced from plastic, has a partially cylindrical form with a partially cylindrical outer wall  38  and a planar outer wall region  40 , which both protrude downward from a cover  42  in which a multiplicity of holes  44  has been incorporated. A multiplicity of pins  46 , which according to FIG. 5 have a conically tapering form, protrudes downward from the cover  42 . 
     A tongue  48 , which is parallel to the cover  42  and lies below the hinge  20  in the fitted state of FIG. 1, protrudes from the lower edge of the planar outer wall region  40  of the labyrinth insert  36 . 
     The labyrinth insert  36  is fastened with its upper, radially protruding edge  62  with a snap fit in a receiving edge  64  of the lid  18 . 
     FIG. 1 furthermore shows that with the lid  18  closed, the labyrinth insert  36  forms, with the lower end  50  of the partially cylindrical outer edge  38  and with its tongue  48 , a seal with respect to the inner wall  52  of the housing  12 . Between the cover  42  and the inside  54  of the lid  18  there is bounded a flat clearance space  56  which is connected via three lateral passage openings  58  to an annular space  60  between the labyrinth insert  36  and the inner wall  52  of the housing. 
     In the fitted state of the plug  10 , the rising gases also entrain evaporating liquid which, as it passes between the pins  46  of the labyrinth insert  36 , precipitates on the pins  46  and condenses because of the temperatures prevailing there which are lower than in the lower region. The condensed liquid then runs downward on the pins  46  and drips back into the cell, into which the plug  10  has been inserted. Before the rising gases pass via the flat clearance space  56  and the passage opening  58  into the annular space  60  in order to pass from there via the degassing opening  28  into the open, liquid which remains entrained can precipitate in the flat clearance space  56  and condense there. The condensate can run off downwardly from this clearance space  56  through the holes  44  in the cover  42  of the labyrinth insert  36 . 
     If the twice condensed gas passes into the annular space  60 , a small amount of condensate will once more be deposited there and can flow back into the cell through a narrow gap  86  between the tongue  48  and housing wall  52 . 
     If during a check the lid  18  is pivoted about the hinge  20  into its opening position, the condensate still adhering to the pins  46  flows back into the cell via the open lower side  14  of the housing  12  due to gravitational force. 
     Trials using the plugs according to the invention have revealed that a considerably greater return of liquid into the battery cell is achieved compared to previously known plugs without a labyrinth insert  36 . Instead of having to top up the battery cells in the case of previous plugs daily, for example, topping up only every second or third day is now sufficient. 
     In an embodiment of the invention according to FIGS. 1,  7 , and  8 , a first holder  66  which is tapered conically downward is inserted into the lower opening of the housing  12  and a second small holder  70  of smaller diameter protrudes from the open bottom  68  of the first holder. The holder  66  and small holder  70  are likewise produced in one piece from plastic by injection molding. On its upper, cylindrical edge  72 , on the left side in FIGS. 7 and 8, the holder  66  is provided with barbs  74  which bear in a frictionally engaged manner against the cylindrical inner wall  52 ′ of the housing  12  because of the radial flexibility. 
     Four latching sockets  76  are incorporated into the inner wall  52 ′ of the housing  12  lying axially one above another on one side, and the latching stud  84 , shown on the right in FIG.  7  and which has a rectangular profile, can snap into said latching socket. This enables the holder  66  to be fixed at four different heights within the housing  12 . The barb  74 , which is formed in addition to the latching stud  84 , serves as an end stop and prevents the holder  66  from falling out in its lowermost position. 
     If the holder  66  is pulled completely out of the housing  12 , it can be reinserted into the latter rotated through 180°, so that the barbs  74 , which are on the left in FIG.  7  and which are shaped differently to the latching stud  84 , now lie in the region of the latching socket  76 , but do not engage therein in a latching manner. In this second position, the holder  66  can therefore be adjusted in a frictionally engaged and infinitely variable manner on the inner wall  52 ′ of the housing  12 . 
     Two longitudinal slots  78  are incorporated lying diametrically opposite each other into the upper, cylindrical edge  72  of the holder  66 , and guide ribs  80  which protrude from the inner wall  52 ′ of the housing  12  engage in said longitudinal slots. Said guide ribs, together with the two longitudinal slots  78 , define the two positions, rotated through 180°, of the holder  66  in the housing  12 . 
     The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalent of the features shown and described or portions thereof, it being recognized that various modifications are possible within the scope of the invention.