Abstract:
A stop damper with a damper member including a receiving space inside which a piston is movably guided between an initial and an inserting position. The piston includes a bellows section and a sealing element, the sealing element resting on a sliding surface of the damper member and the bellows section being allocated to a rest section of the damper member at the initial position. To improve a damping characteristic of a stop damper, the rest section includes at least sectionwise a region that enlarges in the direction of the inserting movement of the piston.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a stop damper with a damper element that has a receiving space inside which a piston is movably guided between an initial position and an inserted position. The piston has a bellows section and a sealing element. The sealing element rests against a sliding surface of the damper element. In the initial position, the bellows section is associated with a contacting section of the damper element. 
     2. Discussion of Related Art 
     A stop damper of this type is taught by German Patent Reference DE 10 2004 060 398 A1. In this case, the damper element has a receiving space delimited by a cylindrical wall that constitutes the sliding surface. A piston with a bellows section formed onto it is inserted into the receiving space. The bellows section has a circumferential sealing element that rests against the sliding surface. The piston has a piston rod integrally formed onto it, which extends out from the damper element. 
     When the piston rod slides into the damper element, this moves the piston and produces a positive pressure in the chamber enclosed by the bellows section, causing the bellows section to inflate and then comes to rest against the sliding surface. The friction forces exerted there brake the insertion movement of the piston. The force on the piston rod is exerted, for example, by a door, a hatch, a drawer, or a mounting component, such as of a hinge. With an impulse-like impact of the door, etc., the stop damper absorbs the impulse, abruptly producing a powerful braking force of the bellows section. As a result, part of the impulse is conveyed back to the door. The door then rebounds a certain distance, which is undesirable. 
     SUMMARY OF THE INVENTION 
     One object of this invention is to provide a stop damper of the type mentioned above but that has a user-friendly damping characteristic. 
     This object is attained if in at least some areas, the contacting section has a region that expands in the direction of the insertion movement of the piston. 
     Because of the expanding embodiment of the contacting section, the distance between the bellows section and the sliding surface varies in the direction of movement. The spacing of the bellows is small, for example, in the region associated with the initial position. Consequently, a braking action between the bellows section and the contacting section can be produced quickly because it is only necessary to thus inflate the bellows section slightly. The piston then simultaneously moves toward the inserted position. Consequently, the cross section of the contacting section that is in contact with the bellows section also widens with the movement of the piston. 
     The bellows section must then be supplied with additional expansion work. This effect assures that braking force is produced quickly, starting from the initial position. However, this braking force is not generated abruptly, which at the very least, sharply reduces the rebound effect on the striking door. 
     According to one embodiment of this invention, the contacting section is conical, in particular in the form of a conical bore, which is associated with a circumferential wall section of the bellows section. 
     The bellows section can come to rest circumferentially against the conical bore with a powerful braking force. In this case, the stop damper can be embodied so that the circumferential wall section of the bellows section has a cylindrical contour. Thus, the spaced-apart region is enlarged continuously as the insertion movement continues. 
     If the construction is selected so that in the initial position, the bellows section is associated with the conically expanding region of the contacting section, then this has a particularly positive influence on the rebound behavior of the stop damper. 
     A reliable seal of the pressure chamber over the entire movement path of the piston can be achieved if between the initial position and the inserted position, the sealing element is guided along a cylindrical region of the sliding surface. 
     If after traveling past or beyond the contacting section during the insertion movement, the bellows section travels past or beyond a cylindrical bore region or a bore region with an altered conicity angle, then this can change the damping curve. It is thus also possible to produce degressive or progressive damping curves. 
     According to one embodiment of this invention, the surface roughness of the sealing element and/or of the sliding surface and/or of the contacting section is produced by a periodic structure, for example a fluted structure. This achieves a favorable guidance during the movement of the piston. 
     The surface structuring also inhibits an excessively powerful adhesive sticking of the bellows section, which would result in a powerful wear on the bellows. In this case, it is possible for the flutes of the fluted structure to be situated with their longitudinal span oriented transverse with respect to the movement direction of the piston. The flutes of the fluted structure in this case can be let into the sliding surface or contacting section circumferentially and transverse with respect to the movement direction of the piston. The flutes are at an angle≧0 and &lt;90° in relation to the movement direction of the piston. 
     Preferably, it is possible for the pitch angle of the flutes to be selected so that the annular, circumferential sealing element overlaps only one flute or a small number of flutes (&lt;20 flutes) over its entire circumference. There is thus always a flute cross section available, which depending on the elasticity of the sealing element, forms a definite air passage gap that on the one hand, assures a smooth sliding of the sealing element and on the other hand, prevents air from escaping too quickly from the pressure chamber during the compression stroke of the piston. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This invention is explained in view of an exemplary embodiment shown in the drawings, wherein: 
         FIG. 1  shows a full side cross sectional view of a stop damper; 
         FIG. 2  shows a full side cross sectional view of a damper element of the stop damper according to  FIG. 1 ; 
         FIG. 3  shows an enlarged depiction of a detail identified by circle III in  FIG. 1 ; and 
         FIG. 4  shows an enlarged depiction of a detail identified by circle IV in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a stop damper with a damper element  10 . The damper element  10  is depicted in the detail view in  FIG. 2 . As shown in the latter depiction, the damper element  10  has an essentially cylindrical, elongated, tubular geometry and encloses a receiving space  12  that is accessible at the rear end of the damper via an installation opening  13  and is accessible at the front end via a through opening  11 . 1 . 
     The installation opening  13  is adjoined by a conical cross-sectional narrowing that constitutes or forms an insertion bevel. The insertion bevel transitions into a steep, radially oriented detent flank  13 . 1 . The detent flank  13 . 1  is adjoined by an diametrically enlarged cylindrical sealing section  13 . 2 . The sealing section  13 . 2  transitions into a conically embodied recess  13 . 3 , which in turn transitions into another cylindrical sealing section  13 . 4 . 
     The recess  13 . 3  has a slight conicity with a small cone angle and narrows in the direction toward the through opening  11 . 1 . After the second sealing section  13 . 4 , a diametrically reduced stop region  13 . 5  is provided. After the stop region  13 . 5 , the receiving space  12  has a sliding surface  12 . 1 , which transitions into a contacting section  12 . 2  in the direction toward the through opening  11 . 1 . 
     The through opening  11  is delimited by a sliding guide  11 . 2 . A stop  11 . 3  in the form of a diametrical reduction is formed between the through opening  11 . 1  and the contacting section  12 . 2 . 
     The sliding surface  12 . 1  has a cylindrical geometry. The contacting section  12 . 2 , however, has a small cone angle. The contacting section  12 . 2  has its largest diameter in the region adjacent to the sliding surface  12 . 1  and narrows in the direction toward the through opening  11 . 1 . 
     As shown in  FIG. 1 , a combination, comprising a piston  33  with a piston rod  31  formed onto it and a support element  20 , is inserted into the receiving space  12 . The piston  33  supports a formed-on, tubular bellows section  34  that transitions into a sealing element  35  at the end. The sealing element  35  is in the form of a thin, circumferential sealing lip. The bellows section  34  encloses a spring receptacle  36 . At the end oriented away from the bellows section  34 , the piston rod  31  is integrally formed onto the piston  33  and terminates at an end cap  32 . 
     The piston  33 , including the piston rod  31 , comprises a flexible material. In order to prevent the piston rod  31  from buckling, it is encompassed by a tubular support element  20  of a harder material. 
     In the connecting region to the piston  33 , the support element  20  rests with a stop element  21  against the piston  33 . The stop element  21  is embodied as a diametrically enlarged collar section. 
     In the initial position shown in  FIG. 1 , the bellows section  34  is positioned in the region of or near the contacting section  12 . 2  of the damper element  10 , as shown in  FIG. 3 . The cylindrical outer contour of the bellows section  34  is circumferentially spaced a short distance apart from the contacting section  12 . 2 . The sealing element  35  is situated in the region of or near the sliding surface  12 . 1  and rests against it. 
     With its stop element  21  against the stop  11 . 3 , the support element  20  prevents the piston  33  from being pulled out through the through opening  11 . 1 . 
     As shown in  FIG. 1 , the end of the damper element  20  oriented toward the installation opening  13  is filled by a stopper element  50 . The embodiment of the stopper element  50  is shown in greater detail in  FIG. 4 , which will be discussed below. 
     The stopper element  50  has a sealing element  51 , which has molded cylindrical outer contour regions that are adapted to the sealing sections  13 . 2 ,  13 . 4 . In this case, these regions have an interference fit so that an air-tight snug fit is produced. The cup-shaped sealing element  51  is adjoined by a detent recess  56 . Adjacent to this, the stopper element  50  terminates at a diametrically reduced end section. The insertion movement of the stopper element  50  is limited in the stop region  13 . 5 . 
     Oriented away from detent recess  56 , the stopper element  50  has a spring mount  52  in the form of a cylindrical element formed onto it, in which a conduit  53  is provided. 
     As shown in  FIG. 1 , a bore  54  is let into the end of the spring mount  52  oriented away from the sealing element  51 . The bore  54  transitions into the conduit  53  via a cross-sectional narrowing. Between the cross-sectional narrowing and the bore  54 , a seat is formed, against which an insert piece  55  rests, in this case a metal ball, that is press-fitted into the bore  54 . 
     The ball closes off the air passage between the bore  54  and the environment. In order to nevertheless obtain an air-conveying connection between the receiving space  12  and the environment, at least one flute extending in the longitudinal direction of the damper element  10  is let into the wall of the bore. The flute cross-section is not overlapped by the insert piece  55  so that the air-conveying connection is reproducibly achieved with a precisely predetermined airflow cross section. 
     The spring mount  52  accommodates a spring element  40  embodied as a helical spring. One end of the spring rests against the sealing element  51 . At the end oriented away from the sealing element  51 , the spring element  40  is placed into the spring receptacle  36  encompassed by the bellows section  34  and its end there rests against the piston  33  so that the piston  33  is prestressed in opposition to the insertion direction of the piston  33 . 
     In order to assemble the stop damper, first, the support element  20  is threaded onto the piston rod  31 . Then this assembly is slid through the installation opening  13  into the receiving space  12 . 
     During this, the support element  20  is slid through the through opening  11 . 1 . The cylindrical outer contour of the support element  20  is guided precisely on the sliding guide  11 . 2 . Then, the spring element  40  is placed into the spring receptacle  36  of the bellows section  34 . Then, the stopper element  50  with its spring mount  52  can be inserted into the spring element  40 . The spring element  40  is placed under stress when the stopper element  50  is slid through the installation opening  13 . The stopper element  50  is then pressed into the sealing sections  13 . 2 ,  13 . 4 , simultaneously causing the detent flank  13 . 1  to snap into place behind the detent recess  56 . 
     The stop damper functions as described in the following specification. 
     Starting from the initial position shown in  FIG. 1 , a force is exerted on the end cap  32  of the piston rod  31 . 
     This force is exerted, for example, by a striking door, a hatch, a drawer, or a mounting component, such as a hinge. Because of this force, the piston  33  is moved toward the installation opening  13 . During this, a pressure is built up in the part of the receiving chamber  12  delimited by the bellows section  34 , which pressure is greater than the pressure in the region of the receiving chamber  12  surrounding the bellows section  34 . This pressure differential causes the bellows section  34  to inflate. As a result, the outer circumference of the bellows section  34  comes to rest against the inner wall of the contacting section  12 . 2 . Due to the conicity of the contacting section  12 . 2 , the bellows section  34  is spaced only a slight distance apart from the contacting section  12 . 2  so that a braking action due to the friction between the bellows section  34  and the contacting section  12 . 2  is achieved quickly. The piston  33  then moves toward the installation opening  13 . Consequently, the braking region of the contacting section  12 . 2  in contact with the bellows section  34  also widens. 
     The bellows section  34  thus is supplied with additional expansion work produced by the pressure difference. This effect assures that starting from the initial position, a braking force is in fact built up quickly, but is not generated abruptly, but it is then maintained. This prevents the piston  33  from absorbing the impact of the door, and other elements, in a quasi-static fashion and from transmitting part of it back to the door, and other elements, in the form of an impulse. The striking door, and other elements, consequently does not rebound or does so only slightly. 
     The sealing element  35  assures a uniformly good sealing action by sliding along the cylindrical region of the sliding surface  12 . 1 . 
     After the bellows section  34  has dissipated a significant portion of the energy, it continues to be guided against the cylindrical sliding surface  12 . 1  in order to smooth out the course of the movement. 
     During the compression stroke, pressure is continuously decreased via the bypass around the insert piece  55 . This pressure decrease occurs very slowly due to the small bypass cross section, thus assuring continuous damping. 
     Once the stress on the piston rod  31  is relieved, the spring element  40  pushes the piston  33  continuously out of the inserted position, into the initial position shown in  FIG. 1 . During this, a pressure compensation occurs via the bypass. During the resetting action, the bellows section  34  no longer rests against the damper element  10 . 
     Both the sliding surface  12 . 1  and the contacting surface  12 . 2  are produced by a fluted structure. The longitudinal span of the flutes extends transverse to the movement direction of the piston  33 . The fluted structure is predetermined in the tool mold or the injection-molding die. 
     Preferably, a fluted structure is produced over a rotated surface so that the flutes extending around the inner wall of the cylinder are at an angle in relation to the movement direction of the piston  33 . The angle or infeed here is small enough, &lt;5° in the present case, so that the lip-shaped sealing element  35  always travels over only a small number of flutes, such as &lt;20 flutes, in the sealing region. This achieves an optimal sliding and wear behavior of the sealing element  35 . 
     The fluted structure shown in  FIG. 12  assures a sufficient sealing action so that the sealing element assures the pressure buildup. 
     The fluted structure, the negative contour of the mold, can be polished so that the fluted structure is of partition walls. This fluted structure has a high load-carrying portion, which has an optimal influence on the sliding properties.