BACKGROUND OF THE INVENTION 
       [0001]    The present invention generally relates to apparatus for connecting equipment so that hydraulic and other fluids can be transferred between equipment and, more specifically, to apparatus for connecting equipment where fluids may be pressurized and where spillage and leakage are highly undesirable 
         [0002]    In many applications, flexible conduits such as hoses and tubing are inappropriate for connecting equipment, and equipment may be heavy and cumbersome to manipulate in order to align connectors needed to transfer hydraulic and other fluids. Connectors are needed to enable quick and reliable connections between such equipment. 
         [0003]    Often the hydraulic fluid is under pressure and provides energy to perform some mechanical task. Connectors are needed that can be coupled and decoupled quickly and without requiring tools. Also, connectors must provide non-leaking connections. Furthermore, connectors are needed that automatically close when decoupled so that the fluid does not continue to flow out of the decoupled connector. 
         [0004]    There are many examples of fluid connectors in the known art, most of which are intended for use with flexible conduit such as hose and tubing. Such connectors rely on a user to provide alignment by joining the hose coupler by hand. Many of them include spring operated internal valves to prevent fluid leakage when disconnected. They often include spring-loaded latching elements to enable “push-to-connect” functions. The spring-operated elements of such couplers can require significant force be overcome when attaching to the connecters. Furthermore, the latching elements can require manual release in order to decouple form the connector. This makes these connectors unsuitable for applications where heavy or fixed-position appliances need to be fluidly connected and where flexible conduit is not suitable. 
         [0005]    One coupler in the prior art, U.S. Pat. No. 4,222,411 by Herzan, has a coupler body with two opposing coaxial female connectors for accepting two separate male connectors. The coupler body is substantially cylindrical with female connections aligned axially at either end of the cylinder. The particular coupler can accept one threaded male connector and one push-to-connect nipple. 
         [0006]    The Herzan coupler has an inner plug that slides axially within the coupler body, the plug being movable via a cam-action rotary knob that extends radially from the cylinder body. The plug provides the female connection for the threaded male connector. In a closed position, a movable stopper within the coupler body seals off the opposite female connections from each other. In an open position, the rotary knob moves the inner plug with the threaded connection axially towards the opposite connection, in the process shifting the movable stopper to open a fluid path between the two female connections. 
         [0007]    The Herzan coupler requires relative movement between the two attached connecters to effect coupling and decoupling, so it is not appropriate for fixed mounting to two hydraulic appliances. In addition, it also relies on spring-operated latches and valves to hold and seal the connectors. 
         [0008]    Another connector from the prior art, U.S. Pat. No. 6,283,151 to Countryman et al, can be fixedly mounted to one appliance, yet requires the mating appliance be inserted into the coupler to form the connection. Like the aforementioned Herzan coupler, it has spring operated latches and internal valves. 
         [0009]    As can be seen, there is a need for fluid connectors that can be fixedly mounted to hydraulic appliances and then coupled and decoupled without depending on flexible conduit and without requiring movement of either appliance in order to facilitate coupling and decoupling. Also, there exists a need for fluid connectors that can be employed without restoring forces that must be overcome in order to couple to the connector. Such restoring forces, usually the result of spring latches and spring operated internal valves, can be significant and make both mounting of fixed appliances and coupling to the fluid connector unnecessarily difficult. 
       SUMMARY OF THE INVENTION 
       [0010]    In one aspect of the present invention, a fluid coupler comprises a main fluid housing being positionally fixed to and fluidly connected to a first hydraulic appliance; a main fluid passage circumscribed by the main fluid housing; a plug assembly being movable within the main fluid passage between a coupled position and a decoupled position; a remote fluid receiver positionally fixed to and fluidly connected to a second hydraulic appliance; the remote fluid receiver being engaged by the plug assembly in the coupled position; the plug assembly in the coupled position providing fluid communication between the main fluid housing and the remote fluid receiver; and the main fluid housing being wholly disengaged from the remote fluid receiver when the plug assembly is in the decoupled position. 
         [0011]    In another aspect of the present invention, a fluid coupler comprises a main fluid housing, the main fluid housing having a main fluid inlet; the main fluid housing being positionally fixed to a first hydraulic appliance so that the main fluid inlet is in fluid communication with the first hydraulic appliance; a main fluid passage being circumscribed by the main fluid housing; a plug assembly being movable within the main fluid passage between a coupled position and a decoupled position; a remote fluid receiver, the remote fluid receiver having a receiver outlet; the remote fluid receiver being positionally fixed to a second hydraulic appliance so that the receiver outlet is in fluid communication with the second hydraulic appliance; the remote fluid receiver being engaged by the plug assembly in the coupled position; the plug assembly in the coupled position providing fluid communication between the main fluid housing and the remote fluid receiver; and the plug assembly, when moving between the coupled position and the decoupled position, moving with respect to the main fluid inlet and with respect to the receiver outlet. 
         [0012]    In a further aspect of the present invention, a fluid coupler comprises a main fluid housing, the main fluid housing having a main fluid inlet; the main fluid housing being positionally fixed to a first hydraulic appliance so that the main fluid inlet is in fluid communication with the first appliance; a main fluid passage being circumscribed by the main fluid housing; a plug carrier sliding concentrically within the main fluid passage between a coupled position and a decoupled position; the plug carrier having a plug extension ring sliding concentrically and fluid-tightly within the plug carrier; the plug extension ring being biased outwards from the plug carrier and having an extension opening facing outwards from the plug carrier; a plug fixed to the plug carrier and sliding concentrically within the plug extension; the plug retracting the plug extension ring and sealing the extension opening when the plug carrier is in the decoupled position; the plug extending beyond the extension opening and unsealing the extension opening to expose the main fluid passage when the plug carrier is in the coupled position; a remote fluid receiver being engaged by the plug carrier in the coupled position; the remote fluid receiver being positionally fixed to a second hydraulic appliance; the remote fluid receiver being fluidly connected to the second hydraulic appliance; the plug carrier in the coupled position providing fluid communication between the main fluid housing and the remote fluid receiver; and the plug carrier in the decoupled position being wholly disengaged from the remote fluid receiver. 
         [0013]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a sectional view of an embodiment of the invention in the decoupled position; and 
           [0015]      FIG. 2  is a sectional view of an embodiment of the invention in the coupled position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. 
         [0017]    Various inventive features are described below that can each be used independently of one another or in combination with other features. However, any single inventive feature may not address any of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below. 
         [0018]    The present invention generally relates to a fluid coupler for connecting two hydraulic appliances. The coupler may be useful when flexible conduit is unsatisfactory for establishing fluid connection between the appliances and where it is not practical to move the appliances with respect to each other in order to connect to the coupler. An example of an application for the invention is an aircraft-mounted fluid manifold connected to a pump mounted in a fixed position with respect to the manifold. In this application, flexible conduit is not available for use, and the weight and bulk of the pump make it difficult to manipulate the pump in order to connect to a conventional coupler with internal springs and restoring forces. 
         [0019]    The fluid coupler of the present invention provides progress over the prior art in that the components of the coupler can be fixedly mounted to two hydraulic appliances, for example a pump and a fluid manifold, without overcoming internal restoring forces present in the coupler. After mounting the coupler, the coupler can be adjusted to establish fluid communication between the two appliances. Similarly, the coupler can be adjusted to terminate fluid communication, again without requiring movement of the either of the two appliances. 
         [0020]    Referring to  FIGS. 1 and 2 , which show an embodiment of the invention in a decoupled position and a coupled position, respectively, the fluid coupler  10  may have a main fluid housing  11  circumscribing a cylindrical main fluid passage  15 . The main fluid housing may have at least one main fluid inlet  14  extending radially outwards from the main fluid passage  15 . The main fluid housing  11  may be fixed to a first hydraulic appliance  41 , with the main fluid housing  11  aligned so that the first hydraulic appliance  41  is in fluid communication with the main fluid inlet  14 . The main fluid housing  11  may have a main annular channel  13  around the main fluid passage  15  with a plurality of main fluid inlets  14  connecting the annular channel  13  to the main fluid passage  15 . As used here and throughout, “inlet” and “outlet” describe possible directions of fluid flow through fluid passages and do not limit the invention to specific flow directions. The main fluid housing  11  may be fixed to the first appliance  41  via a main mounting flange  12 . The main fluid housing  11  may also include a threaded ring  16 . The threaded ring  16  may be positioned coaxially with the main fluid passage  15 . 
         [0021]    The coupler  10  may have a plug assembly  20 . The plug assembly  20  may move within the main fluid passage  15  and may move between a coupled position shown in  FIG. 2  and a decoupled position shown in  FIG. 1 . The plug assembly  20  may include a plug carrier  21  sliding concentrically within the main fluid passage  15 , and a plug extension ring  22  sliding concentrically and fluid-tightly within the plug carrier  21 . The plug carrier  21  may be sealed to the main fluid passage  15  via an O-ring  51 . The plug extension ring  22  may be sealed to the plug carrier  21  via an O-ring  52 . 
         [0022]    The plug assembly  20  may also include a plug  25  fixed to the plug assembly  20 . The plug  25  may extend through the plug extension ring  22  and may be guided within the plug extension ring  22  by plug guides, for example the plug guide  29 . 
         [0023]    With the plug assembly  20  in the decoupled position, as shown in  FIG. 1 , the plug extension ring  22  may be biased against the plug  25  by an extension ring spring  61 . An extension ring opening  221  may be sealed fluid-tightly by the plug  25 , thereby preventing fluid flow from the first hydraulic appliance  41  through the main fluid passage  15  out of the extension ring opening  221 . 
         [0024]    The plug assembly  20  may also include a transition ring  24  connected to the plug carrier  21  and a locking adjuster  23  connected to the transition ring  24 . The adjuster  23  may be spring-loaded to allow limited axial movement along the transition ring  24 , but the adjuster  23  may be fixed to rotate with the transition ring  24 . The transition ring may rotate about the plug carrier  21  but may be fixed axially to the plug carrier  21 . 
         [0025]    The transition ring  24  may be threaded to engage the threaded ring  16  and so move the plug assembly  20  axially by rotating the transition ring  24  to engage more thread and to engage less thread. As such, rotating the transition collar  24  may cause the plug assembly  20  to move between the coupled and decoupled position. As the plug assembly  20  approaches the coupled position, the adjuster  23  may contact the main fluid housing  11  and slide axially along the transition ring  24  until a locking tab  17  engages an adjuster notch  26 . 
         [0026]    The plug assembly  20  may slide along the main fluid passage  11  extending the plug extension ring  22  and the plug  25  outwards from the main fluid housing towards a remote fluid receiver  31 . The remote fluid receiver  31  may have a receiver cavity  34  having a receiver outlet  39 . The remote fluid receiver  31  may be positionally fixed to a second hydraulic appliance  42  with the remote fluid receiver  31  aligned so that the second fluid appliance  42  is in fluid communication with the receiver outlet  39 . The remote fluid receiver  31  may have a receiver mounting flange  32  to facilitate mounting to the second hydraulic appliance  42 . The remote fluid receiver  31  may also include a receiver opening  33  configured to accept the plug assembly  20 . The remote fluid receiver may include a receiver annular channel  311  with a plurality of receiver outlets  39  connecting to the receiver cavity  34 . 
         [0027]    The remote fluid receiver  31  may have a poppet valve  35  biased to extend through the receiver opening  33  and to seal the receiver opening  33  to prevent fluid low from the second hydraulic appliance  42  through the receiver cavity  34 . The poppet valve  35  may be biased by the valve spring  62  and the spring  62  may rest in the valve seat  37 . 
         [0028]    As the plug assembly  20  moves to the coupled position, the plug extension ring  22  may extend to enter the receiver opening  33 . The plug  25  may abut the poppet valve  35  and push the poppet valve  35  into the receiver cavity  34  and away from the receiver opening  33 . An extension ring shoulder  28  may abut the receiver opening  33  and seal against a receiver O-ring  38 . As the plug carrier  21  moves further to the coupled position, the plug  25  may extend beyond the plug extension ring  22 , unsealing from the plug extension ring  22  to enable fluid communication between the main fluid passage  15  and the remote fluid receiver cavity  34 . 
         [0029]    With the plug assembly  20  in the coupled position, fluid flow between the first hydraulic appliance  41  and the second hydraulic appliance  42  may be enabled via the main fluid passage  15  connecting with the receiver cavity  34 . 
         [0030]    The first hydraulic appliance  41  and the second hydraulic appliance  42  may be decoupled in two ways. In one case, the plug assembly  20  may be moved from the coupled position to the decoupled position. As the plug assembly  20  moves from the coupled position to the decoupled position, the plug  25  may retract to seal against the plug extension ring  22  and close off the main fluid passage  15  from the receiver cavity  34 . As the plug assembly  20  moves further, the plug  25  may cause the plug extension ring  22  to retract and exit from the receiver opening  33 . Also, while the plug  25  retracts, the poppet valve  35  may extend through the receiver opening  33  and seal the receiver opening  33 , preventing fluid loss from the receiver cavity  34 . When the plug assembly  20  returns to the decoupled position, the plug assembly  20  may be wholly disengaged from the remote fluid receiver  31  and the second appliance  42 . The first hydraulic appliance  41  and the second hydraulic appliance  42  can each be removed for repairs and other maintenance without requiring further disconnection at the coupler  10 . 
         [0031]    Alternatively, the first hydraulic appliance  41  and the second hydraulic appliance  42  may be moved apart with the fluid coupler  10  in place and the plug assembly  20  in the coupled position. In this case, the plug extension ring  22  may extend further outwards from the main fluid housing  15  as the remote fluid receiver  31  moves away with the second hydraulic appliance  42 . The plug extension ring  22  may maintain fluid-tight connection with the remote fluid receiver  31  as the plug extension ring  22  moves to abut the plug  25  and the plug  25  seals against the plug extension ring  22 , closing off the main fluid passage  15  from the receiver cavity  34 . As in the abovementioned case, as the remote fluid receiver  31  moves away from the plug  25 , the poppet valve  35  may extend through the receiver opening  33  and seal the receiver opening  33 , preventing fluid loss from the second hydraulic appliance  42  through receiver cavity  34 . 
         [0032]    It should be noted that the plug assembly  20  may couple and decouple without moving either of the fluid inlets with respect to the appliances. The plug assembly  20  itself may move with respect to the main fluid inlet  14  and with respect to the receiver outlet  39 , so there is no need for flexible conduit to connect to either appliance. This feature makes the fluid coupler  10  especially useful for certain applications where flexible conduit is inappropriate. 
         [0033]    It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
A fluid coupler for connecting two hydraulic appliances together without requiring flexible hoses is described. The fluid coupler enables fluid-tight connecting between fixed position components and allows for separating the hydraulic appliances without decoupling the coupler while maintaining fluid-tightness of both appliances after separation.