Abstract:
A socket of a fluid coupling device includes a housing with a cavity centered on an axis. A pawl, attached to the housing, is pivotable about a pivot location relative to the housing, and has a catch section located axially outward from the pivot location. A spring biases the catch section radially inward. A plug is configured to move axially into the cavity while sliding against the catch section to move the catch section radially outward, against bias of the spring, out of the way of the plug. After an axially-outwardly facing catch surface of the plug passes the catch section, the catch section can pivot radially inward and abut the plug catch surface to capture the plug in the socket.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Application No. 60/738,672, filed Nov. 21, 2005. 
    
    
     TECHNICAL FIELD 
     This application relates to quick connect couplings for a fluid line. 
     BACKGROUND 
     A pressure washer forces liquid under high pressure through a lance and a nozzle at the end of the lance. The nozzle is removably coupled to the lance by means of a quick connect coupling. 
     SUMMARY 
     A socket of a fluid coupling device includes a housing with a cavity centered on an axis. A pawl is attached to the housing, is pivotable about a pivot location relative to the housing, and has a catch section located axially outward from the pivot location. A spring biases the catch section radially inward. A plug is configured to move axially into the cavity while sliding against the catch section to move the catch section radially outward, against bias of the spring, out of the way of the plug. After an axially-outwardly facing catch surface of the plug passes the catch section, the catch section can pivot radially inward and abut the plug catch surface to capture the plug in the socket. 
     Preferably, the spring biases the catch surface radially inward by applying an axially-outward force to the pawl at a location radially outward from the pivot location. An axially-inward facing catch surface of the catch section is configured to abut the plug catch surface to capture the plug and is inclined axially and radially inward so that a force urging the plug axially outward will urge the catch section radially inward. The catch section has an axially-outwardly facing abutment surface configured to abut an axially-inwardly facing abutment surface of the housing to resist a force urging the plug axially outward. The pawl has a release section, located radially outward from the pivot location, configured to be pushed axially inward to pivot the catch section radially outward to release the plug. A radially-inwardly facing surface surrounding the cavity is shaped relative to a radially-outer surface of the plug to enable the plug to be inserted in any of only a finite number of orientations, the number being greater than one. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a spray gun; 
         FIG. 2  is an exploded view of a coupling of the spray gun, including a plug and a socket with two pawls; 
         FIG. 3  is a top sectional view of the plug taken along line  3 - 3  of  FIG. 2 ; 
         FIG. 4  is a perspective sectional view of the plug; 
         FIG. 5  is a perspective sectional view of one of the pawls; 
         FIGS. 6-9  are sectional views illustrating a sequence of steps for coupling the plug to the socket; and 
         FIG. 10  is a sectional view illustrating a step for uncoupling the plug from the socket. 
     
    
    
     DESCRIPTION 
     The apparatus  10  shown in  FIG. 1  has parts that are examples of the elements recited in the claims. The apparatus thus includes examples of how a person of ordinary skill in the art can make and use the claimed invention. It is described here to meet the requirements of enablement and best mode without imposing limitations that are not recited in the claims. 
     The apparatus  10  is a spray gun. It includes a hose  12 , a handle  14 , a lance  16  and a nozzle  18  connected in series. The hose  12  can be connected to a pressure washer base that forces a liquid through the hose  12 . The liquid exits the nozzle  18  in the form of a pressurized spray for removing dirt from household surfaces. As shown in  FIG. 2 , the lance  16  includes a socket  20  adjoined to a tube  22 . The nozzle  18  is adjoined to a plug  30 . The plug  30  and the socket  20  together comprise a quick-connect coupling for coupling the nozzle  18  to the lance  16 . 
     As shown in  FIGS. 3-4 , the plug  30  is centered on an axis A 1 . It has a side surface  32  with a transverse cross-section ( FIG. 3 ) that is symmetric about two perpendicular planes P 1  and P 2  and yields the same shape when rotated a quarter turn about the axis A 1 . The cross-section  32  is generally square, with four sides  34  and four corners  35 . A pocket  36  extends radially inward from each side  34 . A cylindrical inner surface  38  of the plug  30  defines a bore  39 . 
     As shown in  FIG. 2 , the socket  20  includes a housing  40  centered on an axis A 2 . The housing  40  has an inner surface  42  defining a cavity  44 , and a front opening  46 . The inner surface  42  has a generally square transverse cross-section with four corners  47 , to match the transverse cross-section  32  ( FIG. 3 ) of the plug  30 . The corners  47  of the socket  20  are configured to closely receive and catch the corners  35  of the plug  30  to prevent the plug  30  from rotating. The plug  30  can be inserted into the cavity  44  in only a finite number of possible circumferential orientations. The finite number is an even number, and is optimally four as in this example. 
     Two pawls  51  and  52  are located diametrically opposite each other. Each pawl  51  and  52  has two oppositely projecting posts  54  centered on a common pivot axis A 3 . The posts  54  are loosely captured in slots  56  of the housing  40  by lugs  58 . This centers the axes A 3  on pivot locations  59  about which the pawls  51  and  52  can pivot relative to the housing  40 . 
     The pawls  51  and  52  are alike and can be described as follows with respect to the first pawl  51  shown in  FIGS. 5-6 . In the following description, the terms “axially” and “radially” are with respect to the central axis A 2  extending through the socket opening  46  into the cavity  44 . Accordingly, the terms “axially inner” and “axially outer” respectively mean “upper” and “lower” with respect to the orientation of the parts shown in the drawings. 
     The pawl  51  has a central opening  60  below the posts  54 . Above the opening  60 , the pawl  51  has a radially-inner section  62  located radially inward from the posts  54  and a radially-outer section  64  located radially outward from the posts  54 . Below the opening  60 , the pawl  51  has an axially-outer, i.e., “lower”, catch section  66 . 
     As shown in  FIG. 6 , a spring  80  is centered on the housing axis A 2  and wrapped circumferentially about the housing  40 . The spring  80  is compressed by and between a downward-facing spring-bearing surface  82  of the housing  40  and an upward-facing spring-bearing surface  84  of the radially-outer section  64  of each pawl  51  and  52 . The spring  80  applies a directly-axial force to the radially-outer pawl section  64  urging it downward. This pivotally biases each pawl  51  and  52  into an initially closed position in which the pawl&#39;s lower section  66  is urged radially inward (arrows  85 ) into the path of the plug  30  entering the cavity  44 . 
     A release ring  90  is slid upward into an installed position shown in  FIG. 6  in which the ring  90  surrounds the housing  40 . As the ring  90  is slid upward, elastic catches  92  in the ring  90  slide over a rib  94  of the housing  40 . Thereafter, abutment between the catches  92  and the rib  94  prevents the ring  90  from slipping off the housing  40 . The ring  90  has two hooks  96  spaced symmetrically about the axis A 2 . Each hook  96  extends through the opening  60  of the adjacent pawl  51  or  52  to engage the radially-outer pawl section  64 . The radially-outer pawl section  64 , urged downward by the spring  80 , biases the hook  96  downward and thus biases the entire ring  90  downward. 
     In the following procedure for coupling the plug  30  to the socket  20 , the pawls  51  and  52  function in the same manner. The procedure can therefore be described with reference to the first pawl  51 : 
     A first step of the procedure is illustrated in  FIG. 7 . As the plug  30  is inserted (arrow  101 ) into the cavity  44  of the socket  20 , a slide surface  102  of the lower pawl section  66  slides against a beveled surface  104  of the plug  30 . Both surfaces  102  and  104  are inclined axially and radially inward, so that upward movement of the plug  30  moves the lower pawl section  66  radially outward (arrow  105 ), against bias of the spring  80 , into an open position in which the lower pawl section  66  is out of the way of the plug  30 . 
     Next, as shown in  FIG. 8 , the plug  30  pushes the radially-inner pawl section  62  upward. This helps the spring  80  pivot the lower pawl section  66  radially inward (arrow  111 ) back into the closed position shown in  FIG. 9 . Thereafter, the spring bias retains the pawl  51  in its closed position, with the lower pawl section  66  extending into the pocket  36  of the plug  30  to capture the plug  30  in the socket  20 . 
     In its captured condition shown in  FIG. 9 , the plug  30  is prevented from being withdrawn by an upward-facing catch surface  110  of the lower pawl section  66  catching onto and abutting a downward-facing catch surface  112  of the plug pocket  36 . Both surfaces  110  and  112  are tapered slightly downward in the radially-outward direction as indicated by dashed line  114 . This causes any downward force urging the plug  30  out of the socket  20  to reinforce the spring bias in urging the lower pawl section  66  into the pocket  36 . 
     The downward force urging the plug  30  out of the socket  20  is resisted by the posts  54  pulling against the bottom edge  116  ( FIG. 2 ) of the slot  56 . This places the pawl  51  in tension between the lower pawl section  66  and the posts  54 . 
     The downward force is resisted also by a downward-facing abutment surface  120  of the lower pawl section  66  abutting an upward-facing abutment surface  122  of the socket housing  40 . This places the lower pawl section  66  under compression between its upward-facing catch surface  110  and its downward-facing abutment surface  120 . The abutment surfaces  120  and  122  are tapered slightly upward in the radially-outward direction as indicated by dashed line  124 . Therefore, any downward force urging the plug  30  out of the cavity  44  reinforces the spring bias in urging the lower pawl section  66  into the pocket  36 . The loose containment of the posts  54  by the slots  56  ( FIG. 2 ) enables the pawl  51  to rise above the upward-facing abutment surface  122  when the plug  30  is absent. 
     In this example, the force urging the plug  30  axially outward is partially born by the posts  54  and partially born by the abutment surfaces  120  and  122 . In another example, the force is fully born by the posts  54  and not by the abutment surfaces  120  and  122 , so that the abutment surfaces  120  and  122  do not need to abut each other. In yet another example, the force is fully born by the abutment surfaces  120  and  122  and not by the posts  54 , so that the posts  54  can be suspended in the slots  56  ( FIG. 2 ) without contacting the slot edge  116  and the midsection of the pawl  51  is not in tension. 
     During the coupling procedure described above, a hollow stem  130  of the socket  20  enters the bore  39  of the plug  30 . An O-ring  132  is seated in a groove of the stem  130 . The O-ring  132  and the bore surface  38  form an air-tight seal surrounding the stem  130 . A fluid can flow through the stem  130  and the bore  39  to the nozzle  18  ( FIG. 1 ). 
     To release the plug  30 , the release ring  90  is slid upward (arrow  133 ) as shown in  FIG. 10 . This causes a slide surface  134  of the ring&#39;s hook  96  to slide upward against a slide surface  136  of the radially outer pawl section  64 . The hook&#39;s slide surface  134  is inclined, facing upward and radially outward, and the pawl&#39;s slide surface  136  is inclined, facing downward and radially inward. Therefore, the upward movement of the hook  96  imparts to the radially-outer pawl section  64  a force (arrow  141 ) that is angled upward and axially outward. This pivots (arrow  143 ) the lower pawl section  66  out of the plug pocket  36  to release the plug  30 . It also pivots the radially-inner pawl section  62  downward. This, in turn, pushes the plug  30  downward (arrow  145 ) to bring the plug pocket  36  below a radially innermost point  150  of the lower pawl section  66 , to prevent the lower pawl section  66  from reentering the pocket  36  when the user releases the ring  90 . The user can then withdraw the plug  30  from the socket cavity  44 . 
     There are more pockets  36  than pawls  51  and  52 . Since each pocket  36  can receive each pawl  51  or  52 , the number of possible circumferentially different orientations of the plug  30  equals the number of pockets  36 . 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.