Patent Publication Number: US-2005116466-A1

Title: Flat-surface quick coupling tubes extending between a pressurized fluid user device and a fluid feeding means

Description:
BACKGROUND OF THE INVENTION  
      The present invention relates to a flat-surface quick coupling for coupling tubes extending between a pressurized fluid user device and a fluid feeding means.  
      Is already known in the prior art to use quick couplings for coupling flexible hoses to an user device, such as an actuator device provided in an agricultural apparatus or a civil building apparatus, for example a grader or an excavator.  
      Actually, in these machines resilient tubes or hoses for supplying through a delivery tube a hydraulic fluid, e.g. a highly pressurized oil, to an user, such as a cylinder/piston unit or hydraulic motor, are used.  
      To recover or return the hydraulic fluid from the user to the pressure source, such as a pump, it is indispensable to also provide a fluid return tube.  
      Thus, from the prior art is already known to use two separated flexible tubes or hoses provided, at their end portions, with quick couplings for coupling an user device to a pressure source.  
      It is moreover frequently necessary to disconnect the fluid delivery tube and fluid return tube from a set user, for example to replace an operating tool, or to carry out servicing operations to said operating tool.  
      Considering that in the past it was conventional to use two separated tubes having a delivery function, respectively a return function, and considering that the coupling operations were to be performed in dirty environments and, moreover, that the pressurized fluid tube connecting operations were to be performed with a comparatively high speed, the delivery tube could be erroneously connected to a hydraulic fluid return fitting or vice versa, with the risk of a failure of the auxiliary apparatus or of irreparable damages.  
      Finally, a further drawback of prior quick coupling for coupling a delivery tube separated from a return tube, was the necessity of providing two pairs of quick couplings, thereby greatly increasing the system cost.  
     SUMMARY OF THE INVENTION  
      The main object of the present invention is to overcome the above mentioned drawbacks of the prior art, by allowing to use a single quick coupling, both for the pressurized fluid delivery line and return line, while allowing a quick and simple coupling to be obtained, while absolutely preventing any assembling errors in resilient tube connecting operations from occurring.  
      The above object is achieved by a flat-surface quick coupling for coupling tubes extending between a pressurized fluid user device and a fluid feeding means, characterized in that to a female part of the flat-surface quick coupling and a male part of said flat-surface quick coupling are coupled mutually concentric tubes to provide a hydraulic fluid delivery duct and a hydraulic fluid return duct, and that the ducts delimited by said concentric tubes are operatively coupled to a fluid delivery duct, respectively a fluid return duct, said ducts being made inside said female quick coupling part and male quick coupling part, and that said ducts, upon assembling said quick coupling parts, are mutually operatively connected. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The subject matter according to the present invention will be disclosed in a more detailed manner hereinafter and illustrated by an embodiment thereof, given only by way of an example, and shown in the accompanying drawings, where:  
       FIG. 1  is a partially cross-sectioned view illustrating the female part of the novel quick coupling;  
       FIG. 2  is a partially cross-sectioned view illustrating the male part of the novel quick coupling;  
       FIG. 3  is a partially cross-sectioned view showing the components of the quick coupling at the start of the coupling operation or step;  
       FIG. 4  is a partially cross-sectioned view illustrating the quick coupling components in an operatively connected condition; and  
       FIG. 5  shows the quick coupling components at the end of the connecting operation or step, with the flow ducts in an opened condition to allow the hydraulic fluid to flow therethrough. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      As shown in  FIG. 1 , the female part  1  of the flat-surface quick coupling, generally indicated by  2 , comprises an end fitting  3 , including an inner recess  4  for engaging therein an end portion of a resilient tube or hose  5 , defining a first annular duct  6 .  
      The annular duct  6  is coupled to a further duct  7  formed inside the body of the female part  1 .  
      Inside said female part  1  is provided a ring-nut  8  defining a recess  9  for engaging therein an end portion of a second resilient tube or hose  10 , leading to a duct  11  formed inside said female part  1 .  
      The fluid delivery and return tubes  5  and  10  are arranged coaxially with respect to one another.  
       FIG. 2  is a partially cross-sectioned view showing the male part  12  of the quick coupling, also indicated by the reference number  2 .  
      The quick coupling  2  comprises an end fitting  13  having an inner recess  14  in which is engaged a flexible hose or tube  15  defining a first hydraulic fluid flow duct  16  leading to a duct  17  delimited by an insert  18 , including a recess  19  therein is engaged an end portion of a further flexible tube or hose  20  defining a further duct  37 .  
      The fitting  12  rotatably houses a ring-nut  21  locked at an axial position by a resilient ring element  22 .  
      The rotary ring-nut  21  comprises, on a front side thereof, an inner thread  23  allowing the two quick coupling parts  1 ,  12  to be coupled, as the ring nut  21  is screwed on the outer thread  24  of the female part  1 .  
      The coupling steps for coupling the female part  1  and male part  12  are shown in  FIGS. 3, 4  and  5 .  
       FIG. 1  shows moreover that the female part  1  comprises a locally fixed inner tubular stem  25 , known per se in the prior art. The tubular stem  25  operates as a separating element for the ducts  7 ,  11 . As shown, the stem  25  comprises a front enlarged portion engaging an inner annular gasket  26 , and an outer annular gasket  27 .  
      The inner annular gasket  26  is contacted by a tubular sliding ring nut  28 , urged by an urging preloaded spring  29  bearing against a perforated bush  30 , rigid with the end portion of the stem  25 . Against the outer annular gasket  27  is abutted a movable tubular element  31 , having a circumferential enlarged or bulged portion  32 , thereagainst abuts a spring  33  which on a front side thereof is encompassed by a movable ring gear  34  which, at an abutment point  35 , abuts against an outer tubular body  36  of the female part  1 .  
       FIG. 2  shows that the quick coupling male part  12  supports in its inside, through the enlarged portion  18 , a tubular element  40  which is locally fixed.  
      Against said tubular element  40  abuts a spring  41 , thereagainst abuts an enlarged portion  42  of an axially movable tubular element  43  and which, on the front side thereof, is encompassed by a spring  44  thereagainst a further tubular element  45  abuts. Between the tubular element  43 , the tubular element  45  and front end portion of the body  46 , a series of gaskets  47  and  48  are provided.  
      The constructional elements  42 ,  43  and  45  are held in their proper position by a central stem  50 .  
      At the start of the coupling operation for coupling the quick coupling parts  1  and  12 , as shown in  FIG. 3 , the thread  23  of the rotary ring nut  21  is brought into engagement with the outer thread  24  of the tubular body  36 . All the movable elements  34 ,  28  and  31  as well as  45  and  43 , by way of an example, are yet in their starting positions and the ducts  7 , respectively  17 , are shut-off, and, accordingly, no delivery or return hydraulic fluid flow will occur therethrough.  
      By further screwing on the ring nut  21  of the thread  24 , the stem  25  causes the tubular body  45  to be backward displaced against a spring  44 , which will be consequently preloaded. In the meanwhile, the tubular body  43  is also moved backward against an urging spring  41  which is also preloaded.  
      This effect is obtained since the tubular elements  45  is driven by the stem  25  included in the female part  1 . Simultaneously the tubular element  43 , sliding along a stem  50  which is locally fixed inside the male part  12 , is axially displaced, thereby disengaging the duct  9 .  
      In  FIG. 5 , the female part  1  is fully coupled to the male part  12 . Owing to the operation of the locally fixed stem  25 , the body  45  has been backward displaced against the urging spring  44  which is preloaded and, owing to the operation of the body  46 , also the ring nut  34  and tubular body  31  will have been driven toward the rear or back part of the female part  1 , thereby disengaging or clearing the duct  7  while allowing an unhindered hydraulic fluid flow through the duct  7 , in the direction indicated by the arrows (f) in  FIG. 5 .  
      Simultaneously, since also the duct  9  has been fully cleared, it will be possible to provide return fluid, as shown by the arrows (g) in  FIG. 5 .  
      Thus, a quick coupling  2  including the quick coupling parts  1  and  12  allows, for the first time, to use concentric tubes  5  and  10 , and thereby allowing a delivery flow and a return flow inside a single quick coupling  2 .