Abstract:
A method for mounting a latch to a base, the base having an interior cavity for an electronic component, the latch configured to receive a support member for mounting the base to the support member, includes the steps of attaching a release member to the base and holding the release member in a stationary position, placing a latch against the base and forming a connection between the release member and the latch, and moving the release member and latch to a second position where the latch and release member are freely movable between latched and unlatched positions.

Description:
FIELD OF THE DISCLOSURE 
     The disclosure relates to methods which may be used for mounting a latch to a base that carries an electronic component. 
     BACKGROUND OF THE DISCLOSURE 
     Electronic bases are conventionally removably latched on DIN rails or other mounting members. Each base typically includes a pair of hollow shells which house electronic components. The components have exposed contact members for forming electrical connections with the other electronic components outside the base. The base is assembled by placing the electronic components in the shells and then securing the shells together. 
     A latch for securing the base on a DIN rail or other mounting element is typically mounted on the shells when the shells are joined together. Properly positioning the parts of the latch in the shells during assembly can be difficult. Improper location of the parts during assembly of the shells increases the difficulty and cost of manufacturing bases. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Disclosed is a method for mounting a latch to a base. A preferred embodiment of the method includes the steps of attaching a release member to the base, placing the latch against the base, axially moving the latch and the release member along the base, and applying a spring force to the latch. 
     Manufacture of the base is facilitated by positively positioning part of the latch assembly in a fixed initial assembly position in the shells, completing mounting of the latch assembly and then shifting the assembly from the initial position to an operative position. 
     The latch assembly includes a release member, a latch member and a spring for biasing the assembly toward a latched position. The release member is joined to the latch member to facilitate shifting the latch member away from the DIN rail for unlatching. 
     During assembly of the base or module, the release member is secured to the shells forming the base in a known initial or assembly position and the latch member is then inserted into the bottom of the shells to form a physical connection with the positioned release member. The joined release member and latch member are then moved toward the rail to an operative position to free the release member from the base and permit free movement between latched and retracted positions. The spring is inserted into the latch assembly to bias the latch assembly toward the latched position. 
     Positive location of the release member in the shells during assembly assures that the release member is in a known initial assembly position for receiving and forming a physical connection with the latch member. Shifting of the joined members toward the DIN rail frees the release member for operative movement of the assembly between latched and unlatched positions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a base mounted on a DIN rail; 
         FIG. 2  is a bottom view of  FIG. 1 ; 
         FIG. 3  is a view like  FIG. 2 , partially broken away; 
         FIG. 4  is an enlarged view of a portion of  FIG. 1 , partially broken away; 
         FIG. 5  is an exploded view of a base illustrating the position of a release member for assembly in the base; 
         FIG. 6  is a sectional view similar to  FIG. 3  showing the release member in a retracted loading position in the shells forming the base; 
         FIG. 7  is a sectional view showing mounting of the DIN rail latch member on the release member in the position shown in  FIG. 6 ; 
         FIG. 8  is a perspective view illustrating insertion of a return spring into the latch member mounted on the release member; 
         FIG. 9  is a perspective view of the release member; and 
         FIGS. 10 and 11  are perspective views of the top and bottom of the DIN latch member. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Power supply base  10  is removably mounted on elongate DIN rail or support  12  by DIN rail hook  14  on the bottom of the base and DIN rail latch assembly  16  on the bottom of the base on the opposite side of the rail from hook  14 . The base  10  includes a hollow plastic body  18  formed from two hollow shells  20  and  22  joined together at an interface between the shells. The latch assembly extends between a DIN rail location at rail  12  and an actuation location at base end  54 . 
     Module recess  24  is formed at the top of the base  10 . A power conditioning module may be mounted in recess  24  for electrical connection with electronic components in the base, conductors in a process fieldbus connected to the base and a DC power source for the process fieldbus. The process fieldbus conductors and power supply conductors are connected to contact members on the base (not illustrated). Other types of electronic modules may be mounted in recess  24 . 
     A power conditioning module mounted on base  10  regulates the voltage of the DC power supplied to the process fieldbus independent of the voltage of the power supplied to the module from a DC power source. The components in the base may include a circuit board assembly for connecting to the process fieldbus, the power conditioning module and the DC power source (not illustrated). 
     A number of bases  10  are conventionally stacked together side-by-side and are mounted on DIN rail  12 . Bridging connectors (not illustrated) extend through connector openings  26  formed in the opposite sides of base  10  to establish electrical connection between components in adjacent bases. 
     DIN rail  12  includes an elongate, flat base  28  which is typically mounted on a support surface, side walls  30  extending upwardly from base  28  and outwardly extending mounting flanges  32  at the tops of the side walls. 
     DIN rail latch assembly  16  includes a metal latch member  34  mounted on the bottom of body  18  adjacent one side of rail  12 . The latch member  34  is freely movable toward and away from the DIN rail when assembly  16  is operative. Spring  36  biases the latch member toward the DIN rail to engage the adjacent mounting flange  32 . Assembly  16  also includes a flat, elongate release member  38  which is mounted on the bottom of body  18  and is connected to the latch member. When the latch assembly is in the operative position shown in  FIGS. 1-4 , it is movable toward and away from rail  12 . Member  38  is pulled outwardly from the base to release the latch member  34  from the rail for removal of the base from the rail. 
     Release member  38  is positioned in a stepped horizontal groove  40  formed the bottom of body  18  to one side of rail  12 . The groove  40  has a downwardly facing surface which extends along the seam between the shells and includes a wide outer portion  42  extending from base end  54  to groove step  44  and a narrow, inner portion  46  extending from step  44  to an inner end  47  adjacent the DIN rail. Step  44  extends outwardly to either side of narrow groove portion  46 . 
     Release member  38  is formed from metal strip stock and includes flat body  39  having a wide portion  48  located in wide groove portion  42  and a narrow portion  50  located in narrow groove portion  46 . The wide portion  48  of release member  38  provides greater strength and stability for the outer end  52  of the member which is engaged to shift the assembly  16 . The inner end of the release member is narrow in order to engage narrow latch member  34 . Tapered outer end  52  of release member  38  extends outwardly from adjacent base end  54  at the actuation location. Engagement opening  56  is provided in actuator end  52  of release member  38  to facilitate outward shifting of assembly using a tool to release the base from the DIN rail. The release member  38  includes inwardly extending shoulders  58  between the wide and narrow portions  48  and  50 . 
     A pair of spaced apart mounting or attachment fingers  60  extend down from the inner end of narrow strip portion  50 . Center mounting finger  62  is located between fingers  60  a short distance beyond fingers  60 . Fingers  60  and  62  extend down from portion  50  and are bent back toward portion  50  at an angle of 88°, shown as angle X in  FIG. 9 . Mounting arm  78  extends up from base  70  and is bent forward of the base  70  at an angle of 92°. The two nominal angles are supplementary. The interengagement between the angled or raked fingers  60  and  62  and angled or raked arm  78  forms a locked connection between the fingers and arm to prevent disengagement of the release and latch members when outer end  52  of member  38  is pulled to move latch member  34  and unlatch the base from the DIN rail. 
     As illustrated best in  FIGS. 3 and 9 , projections  64  at the inner end of wide release member portion  48  extend a short distance outwardly from the opposed, parallel sides of portion  48  at shoulders  58 . 
     Wide groove portion  42  has opposed, parallel walls  66  extending from base end  54  inwardly to a short distance before steps  44 . See  FIG. 6 . Recesses  68  in sides  66  extend from the steps  44  a distance toward base end  54  and increase the width of groove  40  adjacent the step  44  to a distance slightly greater than the width of release member  38  at projections  64 . The width of wide strip portion  48  away from projections  64  has a close, sliding fit in wide groove portion  42  between sides  66  as illustrated in  FIG. 6 . Narrow portion  50  has a close, sliding fit in groove portion  46 . During assembly of base  10 , release member  38  is held in place in stepped groove  40  in an assembly position. Shoulders  58  are spaced away from steps  44 . Projections  64  frictionally engage sides  66  adjacent groove recesses  68  to hold member  38  in the assembly position, as shown in  FIG. 6  and described below. 
     Latch member  34  is shown in  FIGS. 10 and 11 . The member  34  has a flat base  70 , 90-degree side walls  72  which extend up from the base from opposed base sides, and inwardly bent retention arms  74  extending over the base from the tops of the side walls. Spring access opening  76  is formed through the center of base  70 . Attachment arm  78  extends upwardly from base  70  inwardly of opening  76  and includes a small outwardly facing spring alignment dimple  80  as shown in  FIG. 7 . Latches  82  are formed on the lead ends of side walls  72  and each include an angled lead-in or cam surface  84  and a retention notch  86 . 
     Assembly of the DIN rail latch assembly  16  on body  18  will now be described. Electronic components are mounted in shell body  18  at the same time the latch assembly is mounted in the body. Mounting of the components in body  18  is not described. 
     The latch assembly  16  is mounted in shell body  18  by first positioning release member  38  in the part of groove  40  in one of the open shells  20 ,  22  in an assembly position with outer end  52  extending a distance outwardly from the end  54  of the shell greater than when in the normal operative position of end  52 . The projection  64  engages the side  66  of the groove in the position shown in  FIG. 6  and does not extend into the adjacent groove recess  68 . The mounting fingers  60  and  62  are likewise a distance outwardly from their normal operating range of movement in base  10 .  FIG. 6  shows the release member  38  in the assembly position. 
     With the release member in the assembly position in one shell  20 ,  22 , the second shell  22 ,  20  is positioned over the shell  20 ,  22  in which the release member is positioned and the two shells are moved together to lock the shells together by engagement of post and recess fasteners mounted on the interfaces of the shells. Posts  88  are shown on the interface of shell  22  illustrated in  FIG. 5 . Complementary recesses are provided on the interface of shell  20 . With the shells  20  and  22  secured together, release member is held in the stepped groove  40  in the assembly position shown in  FIG. 6  with projections  64  engaging the sides  66  of wide groove portion  42  to prevent movement of the release member along groove  40 . Narrow portion  50  of release member  38  extends into groove portion  46  and the fingers  60  and  62  extend downwardly into latch window  90  located at the inner end of the release member as shown in  FIGS. 6 and 7 . 
     Next, latch member  34  is positioned below window  90  and is moved upwardly to extend mounting arm  78  between fingers  60  and  62  in window  90  and move the retention arms  74  against the bottom surfaces  94  of shells  20  and  22 , to either side of the walls  96  forming the sides of narrow groove portion  46 . Dimple  80  extends between fingers  60  and is in position to locate spring  36  in member  34 . 
     Latch member arms  74  rest against shell bottom surfaces  94  at assembly. The sidewalls  72  of the latch member are located on the outer sides of walls  96 . The two arms  74  nearest the latches are guided during assembly by channels between retention projections  98  extending outwardly from walls  96 . The two arms  74  positioned away from latches  82  are similarly guided during assembly by channels between retention projections  98  and the outer walls of groove steps  44 . See  FIG. 6 . 
     Next, the outer end  52  of release member  38  is pushed into body  18  to move projections  64  out of interference engagement with groove sides  66  and into recesses  68 . At the same time, the latch member  34  is pushed inwardly and the arms  74  are moved under overhanging features in retention projections  98  to secure the latch member on body  18 . 
     With the latch member  34  and release member  38  positioned inwardly, spring  36  is compressed and moved through access opening  76  in latch member base  70  and released. One end of the spring fits over dimple  80  on latch member arm  78 . The other end of the spring engages wall  100  at the outer side of latch window  90 . With release member projections  64  movable freely in recesses  68 , the joined release member  38  and latch member  34  are in the operative position and are movable toward and away from the DIN rail. Spring  36  normally holds the members in the inner, latched position shown in  FIG. 4 . Outward movement of release member end  52 , typically by inserting a tool in opening  56  and moving the tool away from base end  54 , moves the members  38  and  34  to a retracted, unlatched position with spring  36  compressed between arm  78  and wall  100 . During movement of the latch member  34  between the latched and unlatched positions, the outer arms  74  remain under projections  98  to retain the latch member on the bottom of body  18 . 
     The assembled power supply base  10  is mounted on DIN rail by lowering rail hook  14  below one DIN rail flange  32  and then moving the hook  14  under the flange with the base angled upwardly above the rail. The base is then rotated down so that the other flange  32  engages angled lead-in or cam surfaces  84  on latch member  34 . Downward rotation cams the latch member and release member outwardly until the flange  32  moves past lead-in surfaces  84  and compressed spring  36  returns the members  34  and  38  inwardly to the latched position shown in  FIG. 1 . In this position, the adjacent DIN rail flange  32  is seated in retention notches  86  and base  10  is mounted on rail  12 . 
     The base is removed from the rail by gripping the outer end  52  of release member  38  and moving the end outwardly to retract latch member  34  from engagement with the adjacent DIN rail flange  32 . The base assembly is then rotated up around the recess under hook  14  and freed from rail  12 .