Abstract:
A carbon dioxide absorber for a rebreathing system can be connected to a connection head of the rebreathing system in a simple manner. A centering device ( 43, 44, 45, 46 ), provided in the area of a guide plate ( 40 ) of the absorber ( 4 ), can be caused to mesh with centering pins pointing in the direction of the absorber from the connection head.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. § 119 of German Patent Application DE 10 2007 025 809.9 filed Jun. 2, 2007, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention pertains to a carbon dioxide absorber for a rebreathing system. 
     BACKGROUND OF THE INVENTION 
     A carbon dioxide absorber in the form of an absorber cartridge for a rebreathing system is known from DE 10 2004 020 133 B3. The carbon dioxide absorber is fastened to a connection head of the rebreathing system by means of a pivotable mount. The connection head is used to connect the absorber to the rebreathing system or to also replace a used absorber with a new one even during operation. Valves are provided for this within the connection head; on the one hand, these valves bridge over the gas ducts to the absorber in the form of a bypass when the absorber has been removed, so that no gas can escape from the rebreathing system. On the one hand, a gas connection is established to the absorber when the absorber is connected to the connection head. The absorber has, on its top side, a guide plate, which is pushed into the pivotable mount on the connection head. To center the absorber in relation to the connection head, a centering notch is provided at the guide plate and a centering pin on the mount. The absorber is connected to the connection head when the centering pin is in contact with the wedge-shaped centering notch. However, there always is a certain clearance between the pivotable mount and the connection head because of manufacturing tolerances, so that a mismatch may develop between the gas ducts of the connection head and of the absorber. Since the absorber is normally fastened to the underside of the rebreathing system, the centering notch and the centering pin are normally not visible to the user. Thus, the user cannot readily recognize whether the centering pin is located within the centering notch when the absorber is inserted into the mount in a tilted position. 
     SUMMARY OF THE INVENTION 
     The basic object of the present invention is to improve a carbon dioxide absorber such that it can be connected to the connection head of a rebreathing system in a simple manner. 
     According to the invention, a carbon dioxide absorber is provided for a rebreathing system. The carbon dioxide absorber comprises a connection head at the rebreathing system with the connection head including a pivotable mount. The absorber has an absorber housing with a guide plate on a front side of the absorber housing, the guide plate being able to be pushed into the pivotable mount of the connection head. Guide plate gas ducts are arranged concentrically at the guide plate. Connection head gas ducts are provided in the connection head and with a design corresponding to the guide plate gas ducts. The guide plate gas ducts are for connection to the connection head gas ducts. Guide grooves are provided between the guide plate and the absorber housing for connecting the guide plate to the mount. Centering pins point in the direction of the absorber housing from the connection head. A centering means is in one or more of the guide plate and the absorber housing. The centering means is for meshing with the centering pins from the connection head. 
     The centering means may comprise upper positioning grooves arranged opposite each other with corresponding centering pins in the area of the guide grooves. The centering means may further comprise lower positioning grooves at the absorber housing, the lower positioning grooves extending flush with the upper positioning grooves and for meshing with free ends of the centering pins. The centering pins may taper towards a free end thereof in a wedge-shaped pattern. An outer contour of the centering pins may correspond to an inner contour of the upper positioning grooves. An outer contour of the centering pins may correspond to an inner contour of the lower positioning grooves. 
     The advantage of the present invention is essentially that the absorber is centered in relation to the connection head by upper positioning grooves at the guide plate in combination with centering pins, which engage the upper positioning grooves from the connection head. Increased tightness of the gas ducts is achieved in the connection area between the absorber and the connection head due to the improved centering of the absorber in relation to the connection head. 
     In the absorber known from DE 10 2004 020 133 B3 (which corresponds to U.S. patent application Ser. No. 11/058,624 filed Feb. 15, 2005), the absorber is centered in relation to the pivotable mount only. A centering notch is provided for this purpose in the guide plate of the absorber, and a centering pin, which is located within the centering notch in the inserted state of the absorber, is located at the bracket. Provisions are made according to the present invention for the centering pins to be arranged directly at the connection head such that these mesh with lateral upper positioning grooves at the guide plate of the absorber when the mount is pivoted in the direction of the connection head. The absorber is thus directly centered in relation to the connection head. The upper positioning grooves are preferably arranged in the area of the lateral guide grooves of the absorber. However, other areas of the guide plate or of the absorber housing are also suitable for centering if they can be caused to mesh with the centering pin of the connection head when the mount is pivoted. 
     The centering pins are advantageously arranged opposite each other in the area of the guide grooves. 
     It is especially advantageous to additionally provide in the absorber housing lower positioning grooves, which extend flush with the upper positioning grooves and act as a stop for the centering pins. Centering is further improved by the lower positioning grooves, because the centering pins can be caused to mesh both with the upper and lower positioning grooves. 
     It is advantageous to make the centering pins wedge-shaped in such a way that they taper towards the free end, and to design, in addition, the upper positioning grooves and the lower positioning grooves corresponding thereto. The centering pins are thus in contact with the upper positioning grooves and the lower positioning grooves in a positive-locking manner in the coupled state of the absorber. 
     An exemplary embodiment of the present invention is shown in the figure and will be explained in more detail below. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which the preferred embodiment of the invention is illustrated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a sectional view showing a connection head with an absorber; 
         FIG. 2  is a schematic sectional perspective view showing a connection area between the connection head and the absorber according to  FIG. 1 ; 
         FIG. 3  is a sectional view showing an absorber connected to the connection head; 
         FIG. 4  is sectional perspective view showing the connection area in a longitudinal section between the connection head and the absorber according to  FIG. 3 ; 
         FIG. 5  is a perspective view of the underside of the connection head with the locking element inserted; 
         FIG. 6  is a perspective view of the locking element according to  FIG. 5 ; 
         FIG. 7  is a perspective view showing the absorber according to  FIG. 1 ; 
         FIG. 8  is a perspective view showing the absorber according to  FIG. 7  in the area of the guide plate; 
         FIG. 9  is a side broken away view showing the absorber before insertion into the mount; 
         FIG. 10  is a side broken away view showing the mount with the absorber inserted; 
         FIG. 11  is a perspective broken away view showing the mount with the absorber in a sectional view; and 
         FIG. 12  is a side broken away view showing the mount according to  FIG. 11  with the mount snapped into the connection head. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings in particular,  FIG. 1  schematically shows a longitudinal section of a connection head  1  with a valve means  2  and with an absorber  4  accommodated in a pivotable mount  3 . 
       FIG. 2  schematically illustrates the connection area between the connection head  1  and the absorber  4 . 
     The connection head  1  has a housing  5  with a connection piece  6  for connection to an anesthetic breathing system, not shown more specifically in  FIG. 2 ; a guide sleeve  7 , which accommodates the valve means  2 , and an annular locking element  8  within the housing  5  with a release button  9 . 
     The mount  3 , which receives the absorber  4 , has a barb  10 , which snaps into a wall section  11  of the locking element  8 . To connect the absorber  4  to the connection head  1 , the absorber  4  is pushed into the mount  3  and pivoted in the direction of the connection head  1 . Reference is made in this connection to the disclosure of DE 10 2004 020 133 B3, which is part of this specification (and is incorporated by reference and corresponding U.S. patent application Ser. No. 11/058,624 filed Feb. 15, 2005, is also hereby incorporated by reference. 
     The absorber  4  has an inner gas duct  12  with an inner valve crater  13  and an outer gas duct  14  arranged concentrically thereto with an outer valve crater  15 . The gas ducts  12 ,  14  describe the flow paths through the absorber  4 . 
     The inner gas duct  12  passes within the connection head  1  through the interior space of the valve means  2 , and the outer gas duct  14  in an annular space between the valve means  2  and the guide sleeve  7 . A sealing ring  16 , which has an outer sealing lip  17  directed towards the absorber  4 , and an inner sealing lip  18 , which is in contact with an outer ring section  19  of the valve means  2 , is located on the underside of the guide sleeve  7 . The ring section  19  is located between a first cylindrical wall section  20  of the valve means  2  with the larger cross section and a second cylindrical wall section  21  with a smaller diameter, which latter wall section adjoins same. The wall sections  20 ,  21  and the ring section  19  together form a valve housing  201  of the valve means  2 . The inner sealing lip  18  and the ring section  19  form a second sealing area  24  and are designed to interrupt the gas flow in the annular space as a shut-off means when the absorber  4  has been removed from the connection head  1 . 
     The second wall section  21  is provided with an elastomer ring  22  at its free end, which extends in the direction of the absorber  4 . When the absorber  4  is pivoted in the direction of the connection head  1 , the outer sealing lip  17  lies on the outer valve crater (seat)  15  and forms a first sealing area  23 . The elastomer ring  22  is located on the inner valve crater  13  in this position of the absorber  4 . 
     A flow valve  31  with a valve body  25 , which is in contact with a sealing lip  26 , is located on the top side of the first wall section  20  of the valve means  2 . The valve body  25  is pressed by a compression spring  27  against the sealing lip  26 . The valve body  25  is in contact with a projection  29  of the housing  5  via spacers  28 . Due to the fixation by means of the spacers  28 , the valve body  25  always has a fixed position in relation to the housing  5 . The flow valve  31  opens when the valve housing  201  is displaced in the direction of the spacers  28 . In the position of the absorber  4  shown in  FIG. 2 , the path of gas  30  extends via the inner gas duct  12  through the free spaces between the spaces  28  to the outer gas duct  14 . 
       FIG. 3  shows the connection head  1  with the connected absorber  4 . 
       FIG. 4  shows the connection area between the connection head  1  and the absorber  4  corresponding to  FIG. 3  in a longitudinal section. Identical components are designated by the same reference numbers as in  FIGS. 1 and 2 . The barb  10  has snapped into the wall section  11  of the spring element  8  in the coupled state. The outer valve crater  15  is in contact with the outer sealing lip  17 . The inner valve crater  13  is located at the elastomer ring  22  and presses the valve housing  201  of the valve means  2  upward against the force of the compression spring  27 . Since the valve body  25  is supported at the projection  29  via the spacers  28  and thus remains in its original position, the sealing lip  26  lifts off from the valve body  25  and the flow valve  31  is opened. At the same time, the ring section  19  separates from the inner sealing lip  18  and the second sealing area  24  is opened. The path of gas  30  from the anesthetic breathing system now leads via the opened flow valve  31  in the inner gas duct  12  and to the absorber  4 . The backflow takes place via the outer gas duct  14 , the opened second sealing area  24  and the annular gap between the valve means  2  and the guide sleeve  7  back to the anesthetic breathing system. 
     The outer sealing lip  17  is designed in this embodiment as a lip seal with a large deformation area in order to reduce the sealing forces that must be overcome when the mount  3  is coupled with the connection head  1  and to compensate differences in height in the form of manufacturing tolerances. 
     With the absorbed  4  uncoupled, the sealing ring  16  is pulled off from the guide sleeve  7  downward for cleaning purposes and the valve means  2  can be removed and taken apart for cleaning purposes. No tool is necessary for disassembly. The components of the connection head  1  may be manufactured from plastic according to the injection molding process and can be manufactured at a very low cost as a result. 
       FIG. 5  shows a bottom view of the connection head  1  with the valve means  2  removed and with the bracket  3  removed in view “A” according to  FIG. 2 . The mount  3  is fastened pivotably in the bushes  32  of the housing  5 . The locking element  8  has spacing elements  33 , which are in contact with a leaf spring  36 , the leaf spring  36  being supported at projections  34  of the housing  5 . 
       FIG. 6  shows the locking element  8  in a perspective view. The locking element  8  comprises a rigid frame  35 , to which the likewise rigid spacing elements  33  are fastened. When pressure is applied to the release button  9 , the frame  35  deforms and the wall section  11  is displaced in the direction of arrow  37  against the spring force of the leaf spring  36 ,  FIG. 5 . The stroke of the locking element  8  is limited by a contact surface  38 , which is in contact with the housing  5 ,  FIG. 5 , at maximum deflection. When pressure is applied to the release button  9 , the barb  10 ,  FIG. 2 , is released. 
       FIG. 7  illustrates the absorber  4  in a perspective view. A guide plate  40  is fastened to the top side of an absorber housing  39 , and guide grooves  41 ,  42  arranged opposite each other are provided between the guide plate  40  and the absorber housing  30 . The guide plate  40  has upper positioning grooves  43 ,  44  arranged opposite each other in the area of the guide grooves  41 ,  42  and lower positioning grooves  45 ,  46  extending flush with the upper positioning grooves  43 ,  44 . 
       FIG. 8  shows the absorber  4  in the area of the guide plate  40  in a perspective view. Identical components are designated by the same reference numbers as in  FIG. 7 . 
       FIG. 9  shows the absorber  4  before insertion into the mount  3  of the connection head  1 . The connection head  1  has centering pins  47 ,  48 , which are arranged opposite each other and of which only the front centering pin  47  is shown in  FIG. 9 . The centering pins  47 ,  48  are designed as pins tapering in a wedge-shaped manner towards the free end. To connect the absorber  4  to the mount  3 , the absorber is pushed into the underside  50  of the mount  3  along arrow  49 . The underside  50  is beveled for this inwardly, so that the guide plate  40  is held by the underside  50 . The guide grooves  41 ,  42  extend in the area of the centering pins  47 ,  48 . 
       FIG. 10  shows the mount  3  with the absorber  4  pushed in. 
       FIG. 11  shows the mount  3  with the absorber  4  inserted, the mount being cut open along the section lines  51 ,  52 . The centering pin  47  is located in the area of the upper positioning groove  44  of the guide plate  40 . Identical components are designated by the same reference numbers as in  FIGS. 8 and 9 . The mount  3  is fastened such that it can be pivoted about a pin joint 53 fastened to the connection head  1 . 
       FIG. 12  shows the mount  3  connected to the connection head  1 . The front centering pin  47  is located completely within the upper positioning groove  44  and lies with its tip within the lower positioning groove  46 . The rear centering pin  48 , not shown in  FIG. 12 , is located within the rear upper positioning groove  43  and lies with its tip within the lower positioning groove  45 . The free ends of the centering pins  47 ,  48  taper in a wedge-shaped manner, and the inner walls of the upper positioning grooves  43 ,  44  and of the lower positioning grooves  45 ,  46  are designed corresponding thereto, so that the absorber  4  has only a very small clearance in relation to the connection head  1 . 
     While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.