Abstract:
A coupling for several hydraulic pipes has a number of single couplings which have a first coupling member ( 2 ) and a second coupling member ( 4 ). The first coupling member ( 2 ) includes a first valve ( 8 ) and a first cylindrical face ( 16 ). The cylindrical face starts from the first front face ( 7 ). An actuating element moves the first valve ( 8 ) into an open position. A sealing sleeve ( 17 ) is adjustable on the first cylindrical face ( 16 ) in the direction of a longitudinal axis (x). The sleeve ( 17 ) is displaceable by the actuating element from a retracted position, beyond the first front face ( 7 ), into a partly projected position. A second coupling member ( 4 ) has a second valve ( 27 ) and a second cylindrical face ( 31 ). The second cylindrical face ( 31 ) is at least partly covered by the sealing sleeve ( 17 ) in the projected position. The first coupling member ( 2 ) is attached to a first block housing ( 1 ). The second coupling member ( 4 ) is attached to a second block housing ( 3 ) in a position corresponding to the first coupling member ( 2 ) which are attached to the first block housing ( 1 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims priority to German Patent Application 1 99 51 885.8 filed Oct. 28, 1999, which application is herein expressly incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     The invention relates to a coupling that couples several hydraulic pipes and has a number of single couplings corresponding to the number of the to be connected pipes. The single coupling includes, in a known manner, two coupling members, a connector and a muff to receive the connector. 
     In mobile hydraulics, several hydraulic pipes have to be connected and disconnected from one another. Normally a basic vehicle has hydraulic pumps and control valves and various attachable equipment which include hydraulic drives that are supplied with hydraulic energy. If such attachable equipment is connected to the basic vehicle, for example a tractor, up to ten hydraulic pipes may be attached to the hydraulic system. To facilitate the coupling processes, several individual (single) hydraulic couplings are connected to a multi-coupling. Accordingly, several single hydraulic coupling members are installed in a common housing block. Connection means are connected to a second housing block which correspond to second coupling members. Often lever connections are used so that, with a single connection lever, several pipes can be connected to each other. One advantage of the couplings is that several hydraulic pipes, via single couplings, are coupled at the same time. Also, the coupling eliminates any confusion of the pipes of the two housing blocks being connected to each other in the wrong position. If a connection error takes place, dangerous malfunction may take place in the attaching equipment. This may lead to equipment damage. 
     A further problem exists in the couplings of hydraulic pipes. The problem is that the coupling is coupled against a back pressure in one or in two pipes. A very high pressure can build up due to different temperatures in the consumer pipe, the consumer pipe usually being the male coupling member. Also, a very high pressure may be present in the coupling muff, which is often connected by a pipe to the control valve and the pressure supply. During coupling of such hydraulic lines, which are highly pressurized, the pressure increases to such a high level that a coupling-in process is only possible by applying a higher force. During coupling, soft seals such as O-rings are attacked by the pressure medium which flows under high pressure. Leakages may occur. In couplings that have several single couplings that are coupled at the same time, the necessary coupling force is correspondingly multiplied. Then correspondingly stable tensioning levers, as they are for example disclosed in EP 0 522 493 B1 or DE 43 38 665 A1, are necessary to achieve such forces. 
     EP 0 686 801 A1 discloses a flat valve coupling, which is supposed to be suitable to protect the seals from destruction by a medium passing the seals. However, in this design, fluid has to be displaced during the coupling process and the coupling forces are correspondingly high. 
     To avoid the coupling problem under pressure, single couplings are used more often, in which the valves of the single coupling members are only opened after the coupling process. To open the valves, a lever mechanism is provided. The lever is actuated after coupling of the coupling members. Here, the real coupling process is easier, even if the pipes are under pressure. This is due to the fact that an opening of the valves does not take place during coupling, but only afterwards by a lever mechanism. The problem of coupling under pressure is practically solved, as for example disclosed in DE 43 18 840 C2. Here, a switching pin is provided which is axially displaced by a cam-like switching element. Thus, both valves of both coupling members are opened. A design of a flat connector can be selected for this type of coupling. Thus, during coupling, the coupling is oil leakage-free as the coupling valves are closed before coupling or decoupling. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide couplings that are connected to a multi-coupling which secure simple coupling and decoupling and are oil leakage-free during coupling and decoupling. 
     This object is solved according to the invention by a coupling for coupling several hydraulic pipes that has a number of single couplings corresponding to a number of the to be connected pipes. Each coupling includes a first coupling member with a first valve having a first front face, to which the first valve is to be opened. Each coupling has a first cylindrical face, starting from the first front face. Each coupling has an actuating element that transfers the first valve into an open position. Each coupling has a sealing sleeve that is adjustable with a bore on the first cylindrical face in the direction of a longitudinal axis. The sleeve is displaceable by the actuating element from a retracted position into a projected position partly projected beyond the first front face. Each coupling includes a second coupling member that includes a second valve with a second front face to which the second valve is to be opened. Each coupling has a second cylindrical face at least partly covering the sealing sleeve in the projected position. 
     A first block housing is included which receives the first coupling members. A second block housing is included which receives the second coupling members in a position corresponding to the first coupling members. The second block housing is attachable to the first block housing. 
     The actuating element, over a first adjusting path, only adjusts the sealing sleeve to the projected position. In a subsequent second adjusting path, the actuating element displaces the first valve into the open position. Accordingly, a sealed connection is achieved before opening the first valve and second valve, which opening takes place at the same time. 
     The sealing sleeve in its bore has two sealing rings. The rings are arranged at a distance to each other to seal towards the first cylindrical face and the second face. 
     In a further embodiment, an adjustment spring is provided. The spring returns the sealing sleeve into the retracted position. The displacement into the projected position takes place against the force of the adjustment spring. If a closing of the first valve takes place via the actuating element, the sealing sleeve returns under the effect of the adjustment spring into the retracted position. 
     If the actuating element is designed as a pivot lever, pivoting moves the first valve from the closed position into the open position or vice versa. A cam disc impinges a collar of the sealing sleeve to displace it into the projected forward position. The cam disc is designed so that a first displacement of the sealing sleeve takes place to its final projected position via a predetermined rotational path or pivoting path of the actuating element. Afterwards, no further displacement takes place. To retain the projected position of the sealing sleeve, the cam disc has an adjustment circumferential contour. The contour extends around the axis of rotation of the actuating element formed as an actuating lever along an arc of a circle. The radius of the arc is kept constant. In using the adjustment mechanism described in U.S. Pat. No. 5,316,033, it is advantageous that free travel is given via a predetermined pivoting path between the switching element, which impinges the valve to be opened, and the actuating element, adjusted by this and which comprises a switching shaft. The switching shaft can be used to adjust the sealing sleeve. During further pivoting of the actuating element or the actuating lever, an adjustment of the switching element takes place. Thus, the first valve is displaced into the open or into the closed position. When moving from the open position into the closed position a passing of the free travel also takes place, and then the closing of the first and the second valve occurs. After this the adjustment spring becomes effective, so that the sealing sleeve is returned into its original position. 
     Two arrangements in the two block housings can be selected. In the first arrangement, the two coupling members of the single couplings are directly opposed to each other and support each other. However, in the connection of several coupling units or single couplings at the same time, corresponding pressures are active. Accordingly, it is possible that one or several coupling members are under high pressures while the neighboring couplings are not. This results in a load unbalance, which additionally loads the connection elements for the two block housings. To minimize these loadings, a further embodiment of the invention provides a sealing sleeve in the projected position which engages, extends into, an annular chamber formed between the second cylindrical face of the second coupling member and a bore of the second block housing. 
     In the second arrangement, the first block housing is formed by separate parts and has a cover plate. The second block housing abuts the cover plate of the first block housing in the connected condition. Therefore, a direct support of the two block housings takes place. The coupling members are not supported on each other. Accordingly, deformation is prevented. The existing sealing sleeves and the selected actuation lead to no leakage when the two coupling members are not abutting one another. 
     One large problem of all hydraulic couplings is that they can get dirty, especially when used in agricultural equipment. In quick connection couplings, where one coupling member is formed as a connector, and inserted into a second coupling member formed as a muff, and held by retaining balls which engage a sliding sleeve, it is difficult to keep the relatively narrow inlet opening of the muff clean. If after decoupling of a connector the inlet is not closed-up by special sealing caps or if these are defective, it is difficult to clean the inlet. If they cannot be cleaned, penetrated dirt will also be locked in during the coupling process and enter the hydraulic pressure medium. The danger of contamination is especially high in mobile hydraulics since the equipment is often used on building sites and it is extensively spread in agriculture. In such multi-couplings, comprising several single couplings, the danger also exists, that contaminations are locked in during coupling. Cleaning is easier since a whole row of individual coupling members need not be checked and if necessary to be cleaned during each coupling. The majority of multi-couplings are provided with flat valve connectors. Thus, the individual locking elements, which make the access difficult, can be deleted. To prevent damage or contamination of the second cylindrical face of the second coupling member, a protective sleeve is provided and adjustably inserted in the annular chamber. The protective sleeve has an end face, which, in the projected position, is flush with the second front face. The protective sleeve is impinged on by a spring to take up this projected position. Further, the protective sleeve is displaceable by the sealing sleeve into a retracted position. 
     From the following detailed description, taken in conjunction with the drawings and subjoined claims, other objects and advantages of the present invention will become apparent to those skilled in the art. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention are shown schematically (diagrammatically) in the drawings wherein: 
     FIG. 1 is a schematic view of a three coupling member arrangement arranged in a block housing and to be coupled to each other. 
     FIG. 2 is a cross-sectional view through a coupling unit to be connected likewise to each other, after fixing the two block housings to each other, however before the actual opening of the two valves of the coupling members. 
     FIG. 3 is a view similar to FIG. 2, where the two coupling members completely couple and the two valves of the coupling members open. 
     FIG. 4 is a schematical view of the actuating element with the cam disc for setting of the sealing sleeve. 
     FIG. 5 is a view according to FIG. 4 where the actuating element is in a second position. 
     FIG. 6 is a cross-sectional view of an embodiment where the block housings are supported relative to each other. 
     FIG. 7 is a cross-sectional view like FIG. 6, however the annular chamber is extended and receives a protective sleeve. 
     FIG. 8 is a cross-sectional view like FIG. 7 with the sealing sleeve displaced into its projected position and the protective sleeve extending into the annular chamber. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a first block housing  1  with three first coupling members  2 . Each of the three first coupling members  2  include an actuating element  5 . The actuating element  5  is a pivoting lever, pivotable around an axis of rotation. Each first coupling member  2  has a first valve  8 . The first valve  8  can be pushed by the actuating element  5  arranged on the first coupling member  2  into an open or closed position. Second coupling members  4  are opposed to the first coupling members  2 . The second coupling members  4  are mounted in a second block housing  3  in a position corresponding to the arrangement position of the first coupling members  2 . The two block housings  1  and  3  can be connected to each other, via non represented connection means, for example by connection levers, as they are known from the art. 
     FIGS. 2-5 show a first embodiment referring to the more detailed design of the two coupling members. As all the three first coupling members  2  and the second coupling members  4  of FIG. 1 are formed in the same way, only one coupling unit comprising a first coupling member  2  and a second coupling member  4  are described and are representative for all. 
     The first coupling member  2  is received in a recess in the first block housing. A first valve  8  is arranged in the first coupling member  7 . The first coupling member  2  includes a first housing  6  having a first front face  7 . The first valve  8  is arranged towards the first front face  7 . The first valve  8  has a first valve body  11  that abuts a first valve seat  12  in the first housing  6 . The front face of the first valve body  11  is flush with the first front face  7  of the first housing  6 . 
     A switching element  9  is swivelable received in the first housing  6 . The switching element  9  is penetrated by a switching shaft  10 . A breakthrough is provided for this in the switching element  9 . The switching shaft  10  abuts the boundaries of the breakthrough of the switching element  9  by abutment faces which enable a free travel between the two. The switching element  9  impinges, during a rotational adjustment of the switching shaft  10 , on a switching pin  14  and a pressure bar  13 . Due to the rotation, the switching pin  14  is pushed forward beyond the first front face  7  to the front. The valve body  11  is lifted off the seat  12  by the pressure bar  13 . Therefore the first valve  8  is in the open position, as shown in FIG.  3 . 
     A sealing sleeve  17  is arranged axially slidable along the longitudinal axis x on the first cylindrical face  16  of the first housing  6 . In FIG. 2, it is in the retracted position, where its front face terminates flush with the first front face  7 . At its other end the sealing sleeve has a collar  18 . An adjustment spring  19  is arranged between the collar  18  and a cover plate  23  of the block housing  1 . The spring  19  causes the sealing sleeve  17  to take its retracted position, as shown in FIG.  2 . Two sealing rings  21 ,  22 , spaced in the bore  20  of the sealing sleeve  17 , both contact the first cylindrical face  16  in the retracted position of the sealing sleeve  17  according FIG.  2 . 
     A second coupling member  4  is stationarily positioned in the second block housing  3 . The second coupling member  4  opposes the first coupling member  2 . The second coupling member  4  has a second housing  25 . The second front face  26  of the second housing  25  is supported on the first front face  7  of the first housing  6 . A second valve  27  is arranged in the second housing  25 . A valve body  28  of the second valve  27 , according to FIG. 2, is in the closed condition. The valve body  28  abuts against the second valve seat  29  due to the force of the second closing spring  30 . The second housing  25  projects over the front face  32  of the second block housing  3 , so that a second cylindrical face  31  lies free. No contact exists between the front face  32  and the opposed face  24  of the cover plate  23 . 
     Starting from the position shown in FIG. 2, if a rotational movement of the switching element takes place, moving into the position shown in FIG. 3, the switching pin  14  is pushed beyond the first front face  7 . The switching pin  14  impinges on the valve body  28  of the second valve  27 . The second valve body  28  is displaced into the open position. The second valve body  28  forms an opening towards the second front face  26 . At the same time, the first valve body  11  is lifted off the first valve seat  12 . The valve body  11  is in the open position in FIG.  3 . The displacement of the sealing sleeve  17  takes place before this movement. Accordingly, the sleeve  17  projects beyond the first front face  7  and is pushed at the same time over the second cylindrical face  31 . At the same time, the sealing ring  21  extends over the second cylindrical face  31 . Thus, a complete seal between the first housing  6  and the second housing  25  is achieved. Accordingly, an exchange of fluid between the two coupling members  2 ,  4  may take place. The pressure fluid cannot exit to the outside. During displacement, the sealing sleeve  17  enters the free space between the face  23  and the front face  32 . 
     The actuation of the sealing sleeve  17  becomes obvious from FIGS. 4 and 5. A switching position of the actuating element  5  and the sealing sleeve  17  is given in FIG. 4, which corresponds to the one of FIG.  2 . The switching position of the actuating element  5  in FIG. 5 corresponds to the position of the sealing sleeve  17  and the valve position of the first valve  8  of FIG.  3 . However in both the representation the second coupling member has been omitted. Also, FIGS. 4 and 5 are represented in a smaller scale than FIGS. 2 and 3. 
     The actuation element  5  is in the form of a hand lever sitting on the switching shaft  10 , shown in FIG.  2 . The switching shaft  10  carries a cam disc  33  on it outside. The cam disc  33 , together with the actuation element  5 , is swivelable around the axis of rotation  35 . The axis of rotation is represented by the axis of rotation of the switching shaft  10 . Starting from the position shown in FIG. 2, the setting face  34  is flush with the face  36  of the collar  18  of the sealing sleeve  17 . A portion of the circumference of the cam disc  33  has a constant radius and extends concentrically around the axis of rotation. This portion terminates in a face non visible in FIG.  4 . The starting position is limited by an abutment  38 . When starting from the position shown in FIG. 4, the actuation element  5  is rotated counter-clockwise around the axis of rotation. The setting face  34  acts upon the collar face  36  and displaces the sealing sleeve  17  from its represented retracted position to a projected position shown in FIG.  5 . Initially, displacement takes place up to the abutment of the circumference portion  37  against the collar face  36 . Thus, the sealing sleeve  17  projects out of the face  23 . After this, no displacement takes place as long as there is contact with circumference potion  37 . The circumference portion  37  merges into a stopper face, which is provided with a further abutment  39 . Because of this, further movement of the actuation element  9  and thus the switching shaft  10  is prevented. The first adjustment path is represented by the contact of the setting face  34  with the collar face  36 . The second adjustment path, on which the circumference portion  37  is supported on the collar face  36 , is provided for the displacement of the first valve  8 . Also, displacement of the second valve  27  into the open position depends on this movement after the switching shaft  10  has travelled the idling path or free travel relative to the actuation element. The final position, which is limited by the second abutment  39 , can also provide a levelled (flat portion) portion subsequently connected to the circumference portion  37 , to secure a definite position of the actuation element  5 . 
     FIG. 6 shows a modified embodiment. Here, the same parts, which have been described in connection with the FIGS. 2-5, are provided with reference numerals which have been increased numerically by the number  100  compared to the parts of FIGS. 2 and 3. In respect to the description of these parts it is referred to the description of the embodiment of FIGS. 2-5. 
     The deviations will be described in the following. The difference between the embodiment of FIGS. 2-5 is that the second block housing  103 , with its front face  132 , abuts directly with the face  123  of the cover plate of the first block housing  101 . A bore  46  is provided in the second block housing  103  to provide a gap for the sealing sleeve  117 . An annular chamber  40  is provided to receive the sealing sleeve  117  during the displacement from the position shown in FIG. 6 to an advanced (projected) position, which for example corresponds to the position, shown in connection with FIG.  3 . 
     In FIGS. 7 and 8, an embodiment is shown where the annular chamber  40 , provided in FIG. 6, is additionally used to take-up a protective sleeve  41 . The protective sleeve  41  is adjustably supported on the second cylindrical face  231 . The annular chamber  240  is correspondingly deeper. The protective sleeve  41  is acted upon by a spring  42 . The spring  42  pushes the protective sleeve into a projected position. The end face  44  of the protective sleeve  41  contacts the second front face  226 . The movement of the protective sleeve  41  is limited by a retaining ring  43 . During a displacement of the sealing sleeve  217 , starting from the position shown in FIG. 7 into the position shown in FIG. 8, the end face  44  is acted upon by the front support face  45  of the sealing sleeve  217  and is displaced deeper into the annular chamber  240 . 
     The further components of the two coupling members  202 ,  203  correspond in the design to those of FIGS. 2-5. Thus, their respective description is found with the description of FIGS. 2-5. For the essential components reference numerals are given, which, compared to those of FIGS. 2 and 3, for same components the number has been increased by 200 or 100, respectively, in respect to the design of the annular chamber of FIG.  6 . 
     While the above detailed description describes the preferred embodiment of the present invention, the invention is susceptible to modification, variation and alteration without deviating from the scope and fair meaning of the subjoined claims.