US 3781760 A
A terminal receiving snap latch type connector block having an improved flexible latch. Application of a force tending to pull the terminal from the block distorts the latch for improved terminal retention.
Description (OCR text may contain errors)
United States Patent Mancini et al.
Dec. 25, 1973 CONNECTOR BLOCK Inventors: Lloyd Mancini; Howard T. Ysteboe,
both of New Cumberland, Pa.
Assignee: E. i. du Pont De Nemours and Company, Wilmington, Del.
Filed: Mar. 28, 1972 Appl. No.1 238,889
US. Cl. 339/59 M 1m. Cl H01r 13/4s Field of Search ..339/59-6l, 217
References Cited UNITED STATES PATENTS 3/1972 Kobler 339/59 R 2/1969 Sitzler et al. 339/59 M 6/1970 Poingt 339/59 R Primary Examiner-Joseph H. McGlynn Att0rneyTh0mas Hooker 57 ABSTRACT A terminal receiving snap latch type connector block having an improved flexible latch. Application of a force tending to pull the terminal from the block distorts the latch for improved terminal retention.
6 Claims, 6 Drawing Figures CONNECTOR BLOCK The invention relates to connector blocks having snap latches for retaining terminals in insulated cavities. In these blocks the terminal is inserted into the cavity through an entrance and engages latch and bends the latch out of the path of insertion. When the terminal is fully inserted, the latch snaps back so that a latching surface is behind a portion of the terminal to prevent withdrawal. Conventional snap latch connector blocks are disclosed in US. Pat. Nos. 3,012,159 and 3,430,185. U.S..Pat. No. 3,441,661 discloses a connector block in which the terminal is inserted into the cavity and the latch is then pressed down behind a portion of the terminal to prevent withdrawal.
The disclosed connector block includes an improved flexible latch whereby application of a withdrawal force to the terminal brings the terminal into engagement with the latch at a point located on the latching surface outwardly of the cavity so that the withdrawal force buckles the body of the latch down into the cavity thereby engaging the terminal and holding it against the bottom of the cavity. Deformation of the latch increases terminal retention in the. cavity. This feature is highly desirable in connector blocks containingterminals crimped to wires where the wires extend from the terminal outwardly from the block through the terminal entrances. The terminals are mounted oncontact members, which in the case of female terminals may be contact pins. There is a tendency to remove this kind ofa block from the contact members by pulling directly upon the wires rather than by pulling on the block itself.'Pulling on the wires tends to pull the terminals-out of the block, and may completely shear off the latch in conventional housings. In the disclosed connector block terminal pullout retention is increased, thereby reducing latch deformation or the likelihood that the terminals will be accidently removed from the terminal cavity. a
1 Despite the increased retention power of the connector block, individual terminals may be easily removed by bending the snap latch out of the cavity so that it no longer extends into the path ofwithdrawal.
Other objects and features of the invention will become apparent as the-description proceeds, especially when taken in conjunction" with the accompanying drawings illustrating the invention, of which there is one sheet.
IN THE DRAWINGS:
FIG. 1 is a perspective view of a connector block according to the invention;
FIG. 2 is an enlarged perspective view of the snap latch as used in block of F IG. 1; and
FIGS. 3 thru 6 are sectional views taken along line 3-3 of FIG. 1, illustrating a terminal in the cavity and deformation of the snap latch upon application of a withdrawal force.
Connector block 10 illustrated in FIG. 1 includes an insulation housing 12 formed of a suitable dielectric material such as a moldable plastic. A number of terminal receiving cavities 14 are formed on the body and .into the cavity 14. The outer surface of the lip is beveled to facilitate movement of the contact into cavity for engagement with the terminal. While the disclosed terminal 30 includes one type of female disconnect portion 34, it isobvious thatthe' invention is not limited to this specific configuration and that other types of male or female contacts may be used.
The terminal 30 is secured to an insulated conductor 38 by meansof wire crimp 40 and insulationcrimp 42. The wire crimp provides an electrical connection between the terminal and the conductor of wire 38, and the insulation and wire crimp cooperates to form a physical connection between the terminal and the wire.
The snap latch 32 extends from portion 44 of the top wall 26 into a recess 46 in the top wall above the cavity 14. As illustrated in FIG.2, the latch base 48 adjacent top wall 44 has a tapered increased width from that of the projecting latch portion 50. The increased width increases the strength of the latch. 'A nose 52 extends into the interior of the cavity 14 from the free end of portion 50. During insertion of the terminal 40mm the cavity 14, the top of disconnect portion'34 engages the bottom surfaces 54 of the latch so as to flex the latch outwardly of the cavity and permit it to fall back to the position of FIG. 3 when the terminal is fully'inserted.
With the terminal positioned in the cavityas in FIG. 3, terminal portion 56 is positionedfor engagement with the latch surface 58 of nose 52.'This surface faces away from terminal entrance 20 and sloped from the top of nose 60 outwardly of the cavity and back toward entrance 20 to a position where it joins frontwardly facing latch surface 62. Latching surfaces 58 and 62 join at a forwardly facing recess or stop. I
Latch 32 is somewhat flexible to permit bending during insertion of the terminal,- and during application of a withdrawal force. .Withfthe terminal inserted as in FIG. 3, the latch has'snapped back to position nose 52 behind terminal portion 56. The terminal 30 normally rests on the block bottom wall 24. Application of a slight withdrawal force moves the terminal back in the cavity 14 toward entrance 20 so that the terminal portion 56 engages latch surface 58 adjacent nose 60. Application of a further withdrawal force biases portion 56 against sloping latch surface 58 so as to bend latch 32 down to the position of FIG. 4. The latch engaging portion 56 is moved across surface 58 and rests in recess or stop 64. Nose 60 is free of terminal 30. The.
withdrawal force applied to the terminal30 tends to pivot the terminal somewhat in the cavity so that the insulation crimp"42.is lifted away from bottom wall 24, and the top of the-wire crimp rests upon surface 54.
Application of an increased withdrawal force deforms the latch 32, as shown in FIG. 5, by bowing the center portion 76 of the latch between the latching surfaces 58 and 62, and top wall portion 44 downwardly toward bottom wall 24. The latch is bowed in this manner because the terminal engages the latch at recess 64 which is located sufficiently adjacent the top surface of the latch so that the force applied to the latch during withdrawal acts as a torque and tends to bow the latch inwardly of the cavity. Recess 64 is located ajdacent the top surface 72 of the latch in order to assure the desired downward buckling upon application of a withdrawal force. If the terminal engaged the latch during withdrawal at a point adjacent to tip 50, the latch would be subjected to an opposite torque, tending to bow it outwardly of the cavity and thus decreasing the latching capability. As the point of contact between the terminal and the latch is moved along the latch from nose 60 toward the top surface 72, there is a point at which application of a withdrawal force does not subject the latch to a torque, but rather tends to compress the latch without buckling. This point is defined as the withdrawal compression point. In order to insure downward buckling of the latch into the cavity, the point of contact between the terminal and the latch must be located between the withdrawal compression point and the top latch surface 72 facing outwardly of the cavity. Recess 74 is provided in surface 72 to remove material from the outside surface of the latch and thereby increase the desired inward flexing. In this way the withdrawal compression point is moved further into the cavity.
Returning now to the Figures, as illustrated in FIG. 5 the withdrawal force deforms the latch portion 76 to form a bow projecting into interior of the cavity and engaging the top surface of the terminal wire crimp 40, thereby holding terminal 30 firmly against the bottom wall 24. Further increase of the withdrawal force deforms the latch as shown in FIG. 6, so that the downward bow is pronounced and exerts an increased downward force on the terminal. This force markedly increases the resistance to withdrawal and, in the case of the type of terminal illustrated herein, may actually deform the terminal itself. The downward bowing of the latch increases the pullout markedly over that of conventional snap latches in which there is a tendency to shear off the latch portion located in the path of withdrawal. The increased pullout is the result of increased frictional forces between the bottom of the terminal and wall 24 and the surface increased length of the latch in the path of terminal withdrawal. Bowing strengthens the latch and pushes the terminal down, although in some applications only one of these advantages may be obtained.
The rearwardly sloped latch surface 58 is an important feature of the invention. Through the use of this surface the latch 32 may be normally positioned as at FIG. 3, to facilitate ready flexing out of the way of the terminal during insertion with minimalcontact therebetween. in this manner wear between the terminal and the latch is minimized. First withdrawal contact between portion 56 and surface 58 occurs at a point inwardly of the withdrawal compression point and cannot achieve the desired bowing. However, upon application of a withdrawal force, the rearwardly sloped latch surface 58 moves the latch downwardly into the cavity to a position where increase in the withdrawal force results in the desired inward bow in the latch. If the latch 32 is normally extended further into the terminal cavity 14, to a position as in FIG. 4, insertion of terminal would result in undesirable increased wear on the under-surface of the latch.
While the terminal 30 shown herein is of the type disclosed in US. Pat. No. 3,370,265, it is not intended that the invention be limited to use of such a terminal.
Clearly other terminals having male or female disconnects of different design, can be used within the scope of the invention.
While we have illustrated and described preferred embodiments of our invention, it is understood that this is capable of modification, and we therefore do not wish to be limited to the precise details set forth, but desire to avail ourselves of such changes and alterations as fall within the purview of the following claims.
What we claim as our invention is:
1. A connector block having a terminal cavity therein communicating with the outside of the block through a terminal entrance, and a flexible latch extending into the cavity from one side thereof and away from the entrance;
said latch having a nose including a latching face partially in the path of withdrawal of a terminal from the cavity, said face sloping backwardly toward said entrance and said one side and ending at a terminal stop on said face located between the withdrawal compression point of the latch and the outer surface thereof;
said terminal stop being normally positioned out of the path of withdrawal of the terminal whereby upon application of a withdrawal force on the terminal the terminal engages the sloping face, bends the latch into the cavity and slides along the face to said stop.
2. A snap latch type terminal housing including a terminal recess, a flexible snap latch in one wall of the recess with a latch surface facing the normal terminal position in the recess, a nose on the latch located in the path of terminal movement outwardly of the recess; the latch surface including a sloped surface extending from said nose away from the normal terminal location and toward the said wall to a terminal stop normally located out of the path of movement of the terminal toward the latch, whereby upon movement of the terminal toward the latch, the terminal first engages the slope surface, bends the latch into the cavity, and then engages the stop.
3. A connector block having a terminal cavity therein communicating with the outside of the block through a terminal entrance and including a flexible latch extending into the cavity from one side of the cavity; a terminal within the cavity including a first portion located beneath the latch and a second portion projecting above said first portion, the end of the latch lying in the path of withdrawal of said second portion, a withdrawal force being applied to the terminal to bias the second portion of the terminal into engagement with the end of the latch; and the latch including a stressed and downwardly bowed medial portion engaging said first portion and biasing said first portion toward the bottom of the cavity.
4. A connector block as in claim 3 wherein the end of the latch includes a terminal engaging surface extending from the interior of the cavity past a withdrawal compression point to a stop, said terminal second portion engaging said stop.
5. A connector block as in claim 4 wherein said latch surface slopes rearwardly toward said entrance and said stop comprises a recess in such surface.
6. A terminal latch block including a body having a terminal-receiving cavity therein with a terminal entrance in one side of the cavity through which a terminal may be inserted into the cavity; a flexible latch ex- 3,781,760 5 6 tending into the cavity in a direction away from the engaging means into the cavity and away from the entrance; a latching Surface the latch facing away from trance; whereby movement of a terminal in the cavity the entrance and at least partially located wthm the toward the entrance brings the terminal into contact cavity; and terminal engagmg means located on the latching surface at a point outwardly of the cavity with respect to the withdrawal compression point of the the latch downwardly the ylatch; the latching surface sloping from the terminal enwith the terminal engaging means and tends to buckle