PASSIVE CONNECTOR LATCH WITH CAMMING ACTION

Abstract: A passive latch system for matable connector housing (H1, H2), one of which has at least one working surface (SA) depressed and sloping from a reference surface thereof to form part of a latching aperture and the other of which has at least one working surface (SP1) raise and sloping from a reference surface thereof to form part of a latching projection, is characterized in that the sloped working surface also is tapered, and, optionally, inclined.

Description: PASSIVE CONNECTOR LATCH WITH CAMMING ACTION BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a passive latching system for connector housings. Description of the Prior Art As connectors get smaller the force required to withdraw a terminal mounted in a first connector housing from a mated terminal mounted in another connector housing is reduced. Concomittant with this reduction in the withdrawal force is the need to provide a supplementary holding force that assists in retaining the housings together. Passive latch systems have been useful for this purpose in situations, as, in small connectors, where space availability is at a premium. United States Patents 4,787,860 (Bender); 4,900,263 (Manessero et al.); 4,925,398 (Samejima e t al.); and 4,938,710 (Aihara et al.) each exemplify a passive latching system for connecting a pair of connectors. Shown in Figure 1 is a schematic illustration of the basic functional elements of a passive latching system useful to interconnect a first connector housing Hi with a second connector housing H2. The housings Hi and H2, which generally represent any two connector housings, are inserted into mated relationship in the direction of the arrow M (latching direction) and withdrawn from the mated relationship in the direction of the arrow W (unlatching direction). The passive latching system includes a projection P mounted on the housing Hj . The projection P is received in a complementary aperture A formed in the housing H2. The projection P is defined above a reference surface R \ on the housing H] by raised working surfaces S p ι , S p 2- The surface Sp i forms a sloped lead-in ramp while the surface S p 2 defines a sloped exit ramp. The slopes are taken in the x-z plane and are defined with respect to the reference surface R \ . " These slopes are indicated by the respective characters mi n , m c . The slopes need not necesarily be equal. The projection P may take any of a variety of forms and may include the flat surface S p 3, if desired. The edge between the working surface S p 2 and the reference surface Ri is indicated by the character E p . The free edge of the surface S p 2 lies a distance h above the surface R\ . In complementary fashion the aperture A is defined by a depression extending below a reference surface R2 formed on the housing H2. (In Figure 1 the reference surface Rj is defined on what appears as the "top" of the member indicated as Hi while the reference surface R2 is defined on what appears as the "bottom" of the member indicated as H2. The relative position of the members Hi , H2 may be inverted, if desired.) The aperture A is defined by a plurality of surfaces, at least one of which defines a working surface S a . The aperture of which the surface S a forms a part may take a variety of forms, including an enclosed recess as illustrated in Figures 1, 2B through 2G, 3D through 31, 4A and 4B, or a partially enclosed slot, as illustrated in Figures 4C and 4D. The edge between the working surface S a and the reference surface R2 is indicated by the character E a . It is noted that the edges E p and E a extend perpendicular to the latching direction M (and to the unlatching direction W). As the housing Hi is advanced into the housing H2 (in the direction of the arrow M) the lead-in ramp formed by the working surface S p ι on the housing Hj lifts the reference surface R2 on the housing H2. The housing Hi is advanced until the projection P enters into aperture A. The working surface S a then snaps behind the raised working surface S p 2 thus latching the housing Hi to the housing H2. An audible clicking sound usually accompanies the latching of the housin gs. When the parts are to be separated the process is reversed. The housings Hj and H 2 are relatively moved in the direction of the withdrawal arrow W (unlatching direction). In this instance the portion of the raised working surface S p 2 along the edge E p thereof engages along a line of contact with the edge E a of the aperture A in the housing H2. The line of contact between the working surface S p 2 and the edge E a exists over a length portion D (shown as measured along the reference surface Rj) during the withdrawal of the housings. Thus, a relatively substantial force acting in the direction of the arrow W may be required to lift the reference surface R2 as the housings are withdrawn from each other. In view of the foregoing it is believed advantageous to provide a passive latching system that requires a reduced withdrawal force to separate the mated housings. SUMMARY OF THE INVENTION The present invention relates to a passive latch for interconnecting a first and a second connector housing when the same are relatively moved in a latching direction with respect to each other. Each of the housings has a reference surface thereon, one of the housings having at least one working surface depressed from the reference surface thereon to form pan of a latching aperture while the other of the housing has at least one working surface raised from the reference surface thereon to form part of a latching projection. The working surface on one of the housings is sloped with respect to its reference surface. Either the working surface defining part of the latching aperture or the working surface defining the exit ramp surface of the latching projection may be the sloped surface. In accordance with one aspect of the present invention the sloped working surface also is tapered in a direction that is generally parallel with respect to the latching direction. Further, in accordance with another aspect of the invention, the tapered working surface is also inclined in a direction that is substantially perpendicular to the latching direction. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from the following detailed description, taken in accordance with the accompanying drawings, which form a part of this application and in which: Figure 1 is a perspective view of a typical prior art passive latch system; Figure 2A is a perspective view of a latching projection of a passive latch system in accordance with one embodiment of the present invention, while Figures 2B through 2F are various views of a latching aperture of a passive latch system also in accordance with this embodiment of the present invention; Figures 3A, 3B and 3C are respective perspective, plan, and elevation views of a latching projection in accordance with a modified embodiment of the present invention while Figures 3D through 31 present various views of a latching aperture of a passive latch system in accordance with this modified embodiment of the present invention; Figures 4A through 4H, in general, illustrate a particularized implementation of the latching system of the present invention in which Figures 4A and 4B are, respectively, plan and side section views of a housing having a pair of latching apertures formed therein; Figures 4C and 4D are, respectively, plan and side section views of a housing similar to that shown in Figures 4A, 4B in which the apertures in the housing communicate with a slot; Figures 4E and 4F are plan and side section views of a mating housing having a pair of latching projections thereon; Figure 4G illustrates the reaction of the housing of Figures 4A, 4B during the unlatching therefrom of the housing in Figures 4E and 4F; and Figure 4H illustrates the reaction of the housing of Figures 4C, 4D during the unlatching therefrom of the housing in Figures 4E and 4F; and Figures 5A and 5B are schematic diagrams respectively illustrating an explanation of the operational advantages obtained using the embodiment of the invention shown in Figures 2A through 2F and 3 A through 31. DETAILED DESCRIPTION OF THE INVENTION Throughout this application similar reference numerals refer to similar elements in all Figures of the drawings. With reference to Figure 2A shown is a latching projection P' in accordance with this invention. The latching projection P' is formed on the housing Hi that is to be mated with a housing H2 having an aperture A therein as shown in Figure 1. The latching projection P' is improved in that the working surface S p2 defining the exit ramp is tapered in a direction that is generally parallel with respect to the latching direction M (and to the unlatching direction W). The free edge of the surface S p 2 is spaced the height h above the surface Ri . The working surface S p 2 is sloped in the x-z plane at the slope angle m e to the surface Rj . By "tapered" it is meant that the edge E p of the sloped working surface S p2 does not lie on the reference surface Ri in an orientation that is perpendicular to the latching (or unlatching) direction M (or W), but instead lies on the reference surface Rj in an orientation defining a predetermined angle B (in the x-y plane) with respect to the latching (or unlatching) direction M (or W). The angle B may have any convenient value that is less than perpendicular (i. e., ninety degrees) to the latching direction M (and to an unlatching direction W). Alternately stated, and speaking with reference to the unlatching direction W, tapering of the working surface S p 2 results in the lateral end L\ of that working surface S p 2 being presented more forwardly than the lateral end L2 thereof. Thus, owing to the tapering, as the housings are withdrawn only progressive point contact is established between a point on the working surface S p 2 and the edge E a of the working surface S a of the apeπure A in the housing H2. Point contact between the working surface S p 2 and the edge E a generates a prying, or camming, action to assist in lifting the reference surface R2. It should be appreciated that the other element of the passive latching system may be modified in keeping with the present invention. Figures 2B through 2F illustrate the manner in which the structure of the apeπure A' may be modified for use with a complementary latching projection that is generally rectanguloid in shape. (Such a projection is not expressly shown, but would correspond to the shape of the material removed to define an aperture A as seen in Figure 1). As seen from Figures 2B through 2F the working surface S a of such a latching aperture A', that is, the surface depressed from the reference surface R2 to form part of the aperture A', is both sloped in the x-z plane (e. g„ Figure 2D) at an angle m a that is the complement to the angle m c and tapered in the x-y plane (e. g., Figure 2B) at an angle B. The same prying and camming action as earlier described in connection with Figure 2A attends the relative movement (in the directon W) of housings having a passive latching system including such an aperture structure. -o-0-o- A further modification to the projection P' or the apeπure A' (as respectively shown in Figure 2A and Figures 2B through 2G) is respectively illustrated in Figures 3A through 3C and Figures 3D through 31. In these Figures the tapered working surface S p 2 or S a , as the case may be, is also inclined in the y-z plane (the plane lying perpendicular to the latching direction M or to the unlatching direction W). The angle of the inclination is believed best seen in Figure 3C (for the projection P') and in in Figure 31 (for the aperture A'). In each of these Figures the inclination is indicated by the character mj. Owing to the inclination of the surface S p 2 or S a , the one end L \ of the the surface S p 2 lies a distance h from the associated reference surface R2, Ri , while at the other end melds into that reference surface. -o-0-o- With reference now to Figure 4, in general, shown is a particularized implementation of a latching system of the present invention. Figures 4A, 4B and Figures 4C, 4D illustrate two alternative forms of a connector housing H 2 (i. e., a housing having a latching apeπure therein), while Figures 4E and 4F show a connector housing Hi (i. e., a housing having a latching projection thereon). In Figures 4A, 4B the connector housing H2 has provided therein a pair of latching apeπures as indicated in the Figures by the reference characters A \ , A 2 . The latching apeπures Ai , A 2 are located on opposed sides of a polarizing guideway G. The apertures Ai , A 2 are enclosed recesses of the prior art type as shown in Figure 1. The portion of the material of the housing H 2 defines a web W of material that is thinner than the material of the suπounding material of the housing H2. The working surface S a and the working edge E a of each aperture A \ , A 2 are indicated in Figures 4A, 4B. The electrical connection terminals contained within the housing H 2 are in the form of pins T p . In Figures 4C, 4D the material defining the web W is removed, forming a slot S. The latching apertures A \ , A2 in the first connector housing H2 communicate with the slot S. The working surface S a and the working edge E a of each aperture Aj , A2 is also indicated in Figures 4C, 4D. The slotted form of housing H2 is preferred in instances in which a housing has more than three laterally adjacent columns of terminal positions. Each column of terminal positions may have any desired number of rows. The connector housing Hi having a pair of latching projections P'ι, P * 2 thereon is shown in Figures 4E and 4F. The projections P'ι , P'2 are of the type shown in Figure 2A and are disposed on opposite sides of a polarizing key K also formed on the housing Hi. The terminals received in the housing Hi may take the form of the receptacles, and accordingly, appropriately shaped recesses T r are formed in the housing Hi. During the unlatching motion, as illustrated in Figures 4G, as the housing Hi is withdrawn in the direction W the latching projections P'ι, P * 2 cause the housing H 2 (of the form shown in Figures 4A, 4B) to flex, or to buckle, in the vicinity of the relatively thin web portion W. As is illustrated in Figure 4H, when the housing H 2 of the form shown in Figures 4C, 4D is used, as the housing Hi is withdrawn, the latching projections Pi , P2 again cause flexure, or buckling, of the material of the housing H2 defining the slot S. Other particularized arrangements using the passive latching system of the present invention may, of course, be implemented. For example, the projections P'ι , P'2 may be of the type shown in Figures 3A through 3C. Alternatively, projections as shown in Figure 1 may be used, with apertures as indicated in Figures 2B through 2F and Figures 3D through 3F being formed in the complementary housing. It should also be understood that the terminal pins T p may be received in the housing H 2 having the apertures while recesses T r for receptacles may be disposed in the housing Hi having the projections. Any of the housings Hi, H2 shown in this application are preferable fabricated from a plastic material, such as nylon (in the case of the housing Hi) or from a liquid crystal polymer (in the case of the housing H2), using an injection molding process. -o-0-o- The underlying basis by which the force necessary and/or work required to effect withdrawal of the housings Hj , H 2 is reduced using the present invention may be more fully understood with reference to Figures 5 A and 5B. If the portion of the housing H2 (the housing having the apeπure) is viewed as a beam that must be deflected as the housing Hi (the housing having the projection P) is withdrawn therefrom, and if the projection P extends a height h above the pivot point q of the beam, it is apparent from inspection of Figure 5A that an amount of work sufficient to deflect the housing H2 the distance d is required to effect removal of the housings Hi , H2. The force sufficient to effect this work must be applied over the distance D (Figure 1). Using the embodiment of the invention shown in Figure 2A or Figures 2B through 2G, it will be appreciated from Figure 5A that although the work required is the same, the distance over which a removal force is applied is increased (to the distance D', Figure 2A). Moreover, when the embodiment of the invention shown in Figures 3A through3C or Figures 3D through 31 is used, it is required that the beam be deflected only for the distance d', a distance less than the distance d (Figure 5A). Accordingly, not only is the magnitude of the required removal force reduced, but the amount of work required is also reduced. In addition, the beam length (the distance from the pivot point to the end of the beam) is greater, resulting in a longer moment arm. From the foregoing it should be appreciated that any amount of inclination mj (Figures 3C, 31) of the tapered working surface in the y-z plane in accordance with the modified embodiment of the invention will result in a decrease in the amount of work required. Since there is a reduction in the force needed to unlatch the housings from each other, the energy requirements are also less, resulting in greater toughness (i. e., higher reliability over time). -o-0-o- Those skilled in the art, having the benefit of the teachings of the present invention as hereinabove set forth may effect numerous modifications thereto. Such modifications as are discussed herein and which appear to those skilled in the an are to be construed as lying within the scope of the present invention, as defined by the appended claims.

Claims: CLAIMS : 1. A passive latch for interconnecting a first and a second connector housing when the same are relatively moved in a latching direction with respect to each other, each of the housings having a reference surface thereon, one of the housings having at least one working surface depressed from the reference surface thereof to form pan of a latching aperture while the other of the housing has at least one working surface raised from the reference surface thereof to form part of a latching projection, the working surface on one of the housings being (a) sloped with respect to its reference surface, the improvement comprising: the sloped working surface also is (b) tapered in a direction that is generally parallel with respect to the latching direction. 2. The passive latch of claim 1 wherein the depressed surface is the working surface that is tapered. 3. The passive latch of claim 1 wherein the raised surface is the working surface that is tapered. 4. The passive latch of claim 3 wherein the tapered working surface is also (c) inclined in a direction that is substantially perpendicular to the latching direction. 5. The passive latch of claim 2 wherein the tapered working surface is also (c) inclined in a direction that is substantially perpendicular to the latching direction. 6. The passive latch of claim 1 wherein the tapered working surface is also (c) inclined in a direction that is substantially perpendicular to the latching direction. AMENDED CLAIMS [received by the International Bureau on 1 March 1994 (01.03.94); original claim 1 replaced by amended claim 1 other claims unchanged (1 page)3 1. A passive latch for interconnecting a first and a second connector housing when the first and second housings are relatively moved in a latching direction with respect to each other, each of the housings having a reference surface thereon, one of the housings having at least one working surface depressed from the reference surface thereof to form part of a latching aperture while the other of the housing has at least one working surface raised from the reference surface on one of the housings being (a) sloped with respect to its reference surface, the improvement comprising: the sloped working surface also is (b) tapered in a direction that is generally parallel with resect to the latching direction. 2. The passive latch of claim 1 wherein the depressed surface is the working surface that is tapered. 3. The passive latch of claim 1 wherein the raised surface is the working surface that is tapered. 4. The passive latch of claim 3 wherein the tapered working surface is also (c) inclined in a direction that is substantially perpendicular to the latching direction. 5. The passive latch of claim 2 wherein the tapered working surface is also (c) inclined in ' a direction that is substantially perpendicular to the latching direction. 6. The passive latch of claim 1 wherein the tapered working surface is also (c) inclined in direction that is a substantially perpendicular to the latching direction.

Inventors: OLSON STANLEY WAYNE, OLSON, STANLEY, WAYNE
Applicants: BERG TECH INC, BERG TECHNOLOGY, INC.
Application year: 1993
Main classification: H01R13
IPC codes: H01R13