Abstract:
A hydraulic accumulator, especially a hydraulic damper, includes a connecting piece for producing fluid communication between the interior of the hydraulic accumulator and at least two fluid connecting lines in a fitting. The connecting piece is connected to the fitting. The connecting piece is provided with at least one annular channel in its outer periphery in such a way that the connecting section of the connecting piece leading to the interior of the hydraulic accumulator is in fluid communication with the connecting line in the fitting through the annular channel. A compact construction is obtained that avoids the disadvantages of long lines.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a hydraulic accumulator, particularly a hydraulic damper, having a connecting piece providing fluid communication between the hydraulic accumulator interior and fluid connecting lines in a connection fitting. The connecting piece is connected to the connection fitting and the accumulator housing. 
     BACKGROUND OF THE INVENTION 
     Pressure fluctuations can occur in hydraulic systems, involving periodic or even singular occurrences. Cases frequently arise involving discharge flow fluctuations of rotary pumps, operation of blocking and regulating valve systems with short opening and closing cycles, and connection and disconnection of pumps, as well as sudden impact-causing connecting of fluid chambers having different pressure levels. 
     Hydraulic dampers are adapted to the hydraulic accumulator, and serve for the damping of such pressure fluctuations (DE 25 08 960 A1, DE 36 09 534 C1), whereby the use of membrane or diaphragm and bubble accumulators is particularly suitable. Furthermore, the hydraulic dampers according to the type of construction differ from one another in terms of pulsation dampers, suction flow stabilizers, pressure surge dampers and liquid sound insulation dampers or silencers. More detailed individual features concerning these different types of constructions are the subject of the published brochure ‘Hydraulic dampers’, in No. 3.701.7/7.95 of the Hydac Catalog 01, under Heading 4. 
     In known damping solutions using hydraulic accumulators or hydraulic dampers, as disclosed, for example, on page 14 of the above-identified Hydac Catalog, a bubble or membrane/diaphragm accumulator is connected through an adapter or connection member with two fluid connecting lines in the form of tubular lines. The tubular lines extend essentially in a plane. The connecting piece opens in the area of the tubular connecting lines at a right angle thereto, with these lines being part of a connection fitting. In this manner the fluid chamber of the accumulator, consequently the interior of the accumulator, is connected with the fluid connecting lines. When the above described pressure fluctuations are considered, the gas chamber of the accumulator is intended to quench such pressure impacts. Particularly nitrogen is to be used in this case as working gas. 
     DE-A-3 235 234 discloses a low cost hydraulic accumulator whose pressure vessel includes a spherical body. In the pressure vessel, a bubble support part can completely support the membrane bubble, insofar as the interior of the bubble support system remains clear of fluid. For the attachment of the hydraulic accumulator to a fluid supply, the bubble support part has on its bottom a connection piece with an axially symmetrical connecting journal. The connecting journal is provided with an exterior threading for the screwing into a corresponding attachment member. The attachment member carries the fluid supply for the hydraulic accumulator. This hydraulic accumulator, taking this into consideration, has only one fluid attachment extending in the longitudinal direction of the bubble support part, and consequently, requires a quite extensive structural space. Since this hydraulic accumulator is accessible through only one fluid attachment to its connection piece, unfavorable pressure behaviors occur in the system, which particularly is the case insofar as such an accumulator is to be used as damper, stabilizer or the like. 
     U.S. Pat. No. 4,877,055 discloses a throttle valve connected in a hydraulic circuit with a hydraulic accumulator such that when use of the hydraulic accumulator is not required, its fluid stored on the fluid side is provided continuously through the one leak-point-forming throttle valve to the tank side, to attain a complete relaxing of the elastic membrane in the hydraulic accumulator. Damage to the membrane is avoided in such a slackened membrane state, even long-term. 
     The leakage structure comes into use—throttle valve is in the cartridge—and engages over its axially symmetrical connection piece with exterior threading in a connection fitting with two fluid connections for the hydraulic circuit. In the connection piece, a throttle part is mounted with its exterior wall limiting an annular channel, and otherwise is surrounded by the interior wall of the connection piece. A connecting section of the one fluid connection can be attached to the hydraulic accumulator, and then opens in screwing-in direction of the connection piece into the aforementioned annular channel. The annular channel in turn opens through a fluid connection on the tank side into the connection piece. Even that throttle-valve arrangement is of large construction in its longitudinal design, particularly because in order to attain an effective throttle point for the fluid, such a large gap area is provided between connecting piece and throttle part, which is slackened in the direction of the annular channel. Also such arrangement, with its corresponding long fluid line extension, allows no favorable pressure behaviors in the area of the total system with hydraulic accumulator. Also, in the area of attachment and connection piece, it is of large construction. 
     SUMMARY OF THE INVENTION 
     Objects of the present invention are to provide a hydraulic accumulator, particularly a hydraulic damper, which facilitates compact installation, uses fluid connecting lines of short length, and thus, facilitates an improvement of the control of the pressure behavior in the system and improves the potential for exchange by limiting the repair cost. 
     The foregoing objects are basically provided by a hydraulic accumulator having a connecting piece providing fluid communication between the hydraulic accumulator interior and fluid connecting lines in a connection fitting. The connecting piece is provided on its exterior periphery with at least one annular channel. A connecting section of the connecting piece opens into the interior of the hydraulic accumulator and the annular channel, providing fluid communication between the associated fluid connecting line in the connection fitting and the accumulator interior. The connecting section opens at a right angle to the screwing-in direction of the connecting piece into the annular channel. An additional connecting section in the connecting piece provides fluid communication between the accumulator interior and the other connecting line in the screwing-in direction. The hydraulic accumulator or hydraulic damper, with its connecting piece, can be fitted directly into the connection fitting, and particularly, can be screwed together with the connecting piece in such a manner that a compact installation is attained. 
     On the basis of this compact arrangement, the connecting section opens at a right angle into the annular channel. Also, the connecting line lengths in the design of the connection sections are shortened within the connection fitting. Thus, harmful pressure differentials are reduced and the pressure fluctuations can be better damped. Furthermore, an installation can be mounted, for example, directly at the source of the disturbance, for example, directly on the pump which produces the pressure fluctuations. Because of the integral construction of the connecting piece and the accumulator housing being directly engaged in the connection fitting, greater security during assembly can be attained, since fewer structural parts are being used. Also, such hydraulic accumulator can, in a simple operation, be removed from the connection fitting, so that a simpler, lower cost exchange of the hydraulic accumulator is possible. 
     One particular difficulty for the intended block construction lies in the exterior design and the simultaneously required positive guiding in the interior through the connecting piece of the hydraulic damper. That problem is preferably solved by the connecting piece of the hydraulic damper being configured as an axially symmetrical connection journal with exterior threading. 
     A particularly compact construction of the arrangement is attained when, preferably, the second connecting section opens into a separate annular channel extending on the exterior periphery of the connecting piece of the hydraulic accumulator and arranged in the screwing-in direction in a different plane form the first annular channel. Furthermore, the arrangement can provide that the other fluid connection line opens transverse to the direction of screwing-in into the other annular channel carrying fluid. 
     With another particularly preferred embodiment of the hydraulic accumulator of the present invention, the connecting sections open as fluid lines mounted in at least one enlarged hollow space of the connecting piece. This arrangement in turn decreases the damaging delta-p in the feed and discharge lines. Preferably, the fluid connection line is configured as a connection block having standardizable fluid connection lines. In this case, a modular construction system of connection block constructions and the hydraulic damper can be manufactured at low cost. 
     In the case of one particularly preferred embodiment of the hydraulic accumulator of the present invention, its accumulator housing rests on the connection fitting, or maintains a certain axial distance from the connection fitting in the screwing-in direction. Between the housing and the connection fitting or between the connecting piece and the connection fitting only a jointing arrangement is arranged in the form of a sealing ring or a gasket. Since basically only one outwardly working seal is required, this arrangement simplifies and shortens the assembly outlay. 
     With another preferred embodiment of the hydraulic accumulator of the present invention, the connecting piece is provided with an additional jointing arrangement aligned along its exterior threading, or the connecting piece is provided at its open end with an installation cone or tapered socket. As a jointing arrangement, a plastic seal is provided solely on the exterior periphery of the exterior threading. Such arrangements are provided with a reduced jointing means or gasket insert, particularly for the situations wherein very high fluid velocities, or pulsations are in force. The screw threading, in turn, because of its considerable threading length, can be assumed as a seal arrangement for particular special uses. 
     A particularly low-cost and compact construction can be attained insofar as the hydraulic accumulator is embodied as a metal bellows accumulator. The bellow open end is turned toward the connecting piece. The bellows exterior periphery limits a fluid chamber with the housing. Preferably, the housing is likewise configured as the metal bellows, which is itself axially symmetrical. 
     Other objects, advantages and salient features of the present invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings which form a part of this disclosure: 
     FIG. 1 is a partial side elevational view in section of a hydraulic damper configured as a metal bellows accumulator mounted with its connecting piece in a connection block according to a first embodiment of the present invention; 
     FIG. 2 is a partial side elevational view in section of a hydraulic damper configured as a metal bellows accumulator mounted with its connecting piece in a connection block according to a second embodiment of the present invention; 
     FIG. 3 is a partial side elevational view in section of a hydraulic damper configured as a metal bellows accumulator mounted with its connecting piece in a connection block according to a third embodiment of the present invention; and 
     FIG. 4 is a partial side elevational view in section of a hydraulic damper configured as a metal bellows accumulator mounted with its connecting piece in a connection block according to a fourth embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The hydraulic accumulator, partially represented in FIG. 1, is configured particularly as a hydraulic damper, and is provided with a metal bellows  10  intended to damp the pressure fluctuations in a hydraulic circuit. Metal bellows  10  can have a working gas, such as nitrogen, in its interior, and can be provided with a compression spring, or can be sealed off airtight from the environment. The arrangement depends upon the desired predeterminable damping behavior. Metal bellows  10 , as well as the associated housing  12 , are shown only partially. Metal bellows  10  has a stop plate  14  at its open end, seen at the bottom in FIG.  1 . This simple representation of the metal bellows is omitted in FIGS. 2-4 with the metal bellows accumulator housing  12  being represented only partially, insofar as its display is required for understanding of the present invention. Between the exterior periphery of metal bellows  10  with its individual bellows elements and the interior of the associated housing  12  the fluid chamber  16  of the hydraulic accumulator is located. 
     Instead of the partially shown metal bellows  10 , in particular a traditional membrane or diaphragm accumulator or an accumulator with an elastic rubber membrane or piston accumulator arrangement can be used as the hydraulic accumulator or hydraulic damper. Furthermore, the connection technology according to the present invention need not be limited to the connection of hydraulic dampers. Indeed, it can serve as a whole for the connecting of all hydraulic accumulators. Metal bellows  10 , serving as a hydraulic damper, is provided with a connecting piece  18  to produce a fluid-carrying or a fluid communication connection between the interior of the hydraulic accumulator, in other words its fluid chamber  16 , and at least two fluid connecting lines  20 ,  22 , which are part of a connection fitting or block  24 . In the structural situation in FIG. 1, connecting piece  18  is connected completely with connection fitting  24 . 
     Connecting piece  18  is provided on its exterior periphery with a groove-like annular channel  26  passing all the way around. When the installation arrangement has been attained as in the drawings, with connecting section  28  of connecting piece  18  opening into the interior  16  of the hydraulic accumulator, connecting piece  18  is connected fluid-carrying (in fluid communication) through annular channel  26  with the associated fluid connecting line  22  in the connection fitting  24 . Connecting piece  18  is configured as an axially-symmetrical cylindrical connecting journal with exterior threading  30 . The connecting section  28  is at a right angle to the vertical screwing-in direction of connecting piece  18 , and opens in annular channel  26  as soon as the complete screwing-in or the intended structural arrangement has been attained. Another connecting section  32 , extends axially parallel to the screwing-in direction (longitudinal axis), and produces the connection with the other fluid connecting line  20  in the connection fitting  24 . Because annular channel  26  is arranged circumferentially around connecting piece  18 , a fluid-carrying (fluid communication) connection with connection fitting  24  can be produced in any desired rotary setting of the hydraulic accumulator. 
     Connecting sections  28  and  32  are configured as fluid connecting lines and both open in the direction of the fluid chamber into a common hollow space  34  within connecting piece  18  in the area of the transfer over to the other housing  12  of the hydraulic damper. Therefore, at the opposite end the other connecting section  32  opens into another stepped, enlarged hollow space  36 . Since  36  opens in turn into fluid connecting line  20  in coaxial alignment with the screwing-in direction of hydraulic damper  10 . 
     Connection fitting  24  is configured as a modular connection fitting or block, not completely shown, having standardizable connection fitting points (not shown). The other housing  12  in the embodiments of FIGS. 1 and 2 rests on the flat exterior of connection fitting  24 , whereby housing  12  rests on the projecting area of connecting piece  18 . Between housing  18  and connection fitting  24 , a jointing arrangement  38  is arranged in the form of a seal, gasket or sealing ring. In addition or alternatively thereto dependent upon the extended sealing conditions, another seal, gasket or sealing ring  40  in the form of a plastic sealing ring can be provided on exterior threading  30  of connecting piece  18 . Sealing ring  40  additionally supports or totally undertakes the sealing both between the pitches of the screw threads of exterior threading  30  of connecting piece  18  and on the associated interior threading  42  in connection fitting  24 . A particularly good damping of pressure fluctuations can be attained insofar as these fluctuations occur through fluid connecting line  20  on fluid chamber  16  of the hydraulic damper and the volume of fluid is conveyed through fluid connecting line  22  out of connection fitting  24 . The fluid conveyance can be executed continuously or with interruptions. 
     The following embodiments shown in FIGS. 2-4 are explained only insofar as they differ essentially from the embodiment of FIG.  1 . Therefore, essentially the same structural parts are identified with the same reference numbers in all of the figures. 
     In the embodiment shown in FIG. 2, the other connecting section  32  opens into another hollow space  36  or other annular channel  44 , extending through the exterior periphery of connecting piece  18 . Connecting section  32  is arranged in the direction of screwing-in of the accumulator, seen in the view of FIG. 2 in a plane beneath the first annular channel  26 . In this case, the other fluid connecting line  20  is arranged the same as fluid connection  22  in a plane transverse to the screwing-in direction. The two fluid connecting lines  20  and  22  in turn convey fluid and open into the associated annular channels  26  and/or  44 . 
     In the embodiments shown in FIGS. 3 and 4, housing  12  of the hydraulic accumulator or hydraulic damper has an axial spacing between it and the flat top of the block-like connection fitting  24 . In the embodiment of FIG. 3 the sealing occurs by means of a jointing arrangement  46  in the form of a sealing ring or gasket between a shoulder-like narrowing of connection fitting  24  and a flange part  45  of the otherwise essentially cylindrically configured connecting piece  18 . Comparable to the embodiment of FIG. 1, the other connection section  32  in the form of a fluid. connecting line opens into the widened-out connection  20 . 
     In the case of the embodiment as in FIG. 4, only one sealing ring or gasket  40  is provided, once again on the exterior threading  30  between connecting piece  18  and connection fitting  24 . Otherwise, a sealing takes place by means of the conically-shaped part  48  on the open end of connecting piece  18 . Part  48  is supported on its other end by means of a contact cone or tapered socket  50  of connection fitting  24 . In the direction of the view of FIG. 4, an open sort of taphole  52 , with annular channel  26  arranged over it, is provided in the opposite top area. By this means, it is possible to brace the conical areas  48  and  50  counter to one another by means of exterior threading  30  in such a manner that by this arrangement an effective sealing and a secure fluid conveyance are produced both in fluid connecting line  20  and the other connecting section  32 . Comparable sealing means in the bottom area is omitted in the embodiment of FIG. 2, with the sealing being between connecting piece  18  and connection fitting  24  solely through threading area  30 . As a result of this, a threaded seal is attained with a structurally very small seal member between the aforementioned fluid connections  20 ,  22 . 
     With the connection fitting block for pulsation dampers, short connection line lengths are attained and a desired construction of the hydraulic system is possible. The construction is compact. Because of the small number of parts involved, considerable safety and simplicity are attained with the assembly. Furthermore, simple maintenance is guaranteed. The pulsation dampers can be exchanged rapidly for new modular parts. 
     While various embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.