Buckle having increased holding power when under load

Abstract: A buckle (10) comprising: a female receptacle member (18) having a hollow body defining an interior channel (22) which is open at one end; a male latch member (20) having an arm member (44) which is resiliently deflectable in a width direction during insertion into said channel through said open end of said channel; and latch means (40, 54) formed on said female receptacle member (18) and said male latch member (20) for releasable interlocking engagement upon insertion of said arm member (44) into said channel (22) to a locked position; characterised in that said latch means (40, 54) includes an engagement member (32) formed on a surface of said hollow body facing said channel (22) and an engagement member (52) formed on a surface of said arm member (44) facing in a height direction generally transverse to said width direction.

Description: This invention relates generally to buckles, and more particularly to a releasable buckle having a female receptacle member and a corresponding male latch member. Buckles typically include male and female members, one each connected to a free end of a strap, web belt or the like, to provide a connection between the two free ends of the straps. In order to connect the male and female members, the male member includes a resilient latch arm which is inserted within a receptacle in the female member to a locked position, and can be engaged by a user to later disconnect the male and female members. An example of such a buckle is disclosed in our US-A-4150464 which is acknowledged in the pre-characterising portion of the present independent claim and is substantially as illustrated in present Figs. 6 and 7. As shown therein, the female member includes apertures formed in its opposite side walls for engagement with shoulders of corresponding latch arms formed with the male member. Since the shoulders, however, are positioned on the outside surfaces of the latch arms and engage the side walls of the female member, the buckle is susceptible to failure during loading. Specifically, the typical load in the latch arms which acts to remove the latch arms from the female member substantially is directed along the longitudinal axis or centre line "A" of each latch arm. The line "A" is slightly offset from the line "B" which is the line upon which the latch resistance or engagement force substantially is directed between the side walls of the female member and the shoulders on the outside surfaces of the latch arms. Accordingly, as Fig. 7 illustrates, during loading a torque develops between the latch arms and the female member which tends to cause inward rotation of the latch arms in the direction of arrow "C" resulting in failure of the latch arms and/or release of the buckle. Similar buckles are disclosed in US-A-4912950 and US-A-4825515, the latter of which not only has a pair of latching arms 12 which are resiliently flexible in the width direction, with tabs 14 being formed on surfaces of the latching arms 12 facing in the width direction, but also has a safety latching arm 16 which is resiliently flexible in the height direction, with a hook 18 being formed on a surface of the safety latching arm 16 facing in the height direction. It would be desirable to provide a buckle having male and female members where the male member is releasably retainable within the female member and can provide increased holding power when under load. According to the present invention, a buckle comprises: a female receptacle member having a hollow body defining an interior channel which is open at one end; a male latch member having an arm member which is resiliently deflectable in a width direction during insertion into said channel through said open end of said channel; and latch means formed on said female receptacle member and said male latch member for releasable interlocking engagement upon insertion of said arm member into said channel to a locked position; characterised in that said latch means includes an engagement member formed on a surface of said hollow body facing said channel and an engagement member formed on a surface of said arm member facing in a height direction generally transverse to said width direction. Preferably, said hollow body is of generally rectangular cross-section including a top wall, a bottom wall and a pair of side walls with the distance separating said top and bottom walls being less than the distance separating said side walls. In one arrangement, said engagement member formed within said channel extends from either said top wall or said bottom wall and presents an engagement surface for abutment in said locked position with an engagement shoulder presented by said engagement member formed on said arm member, but in another arrangement, said engagement member formed on said arm member has a pair of said engagement shoulders for abutment in said locked position with respective ones of a pair of said engagement surfaces presented by a corresponding pair of said engagement members formed within said channel to extend respectively from said top wall and said bottom wall, with said engagement surfaces being separated by a gap which receives part of said arm member after said arm member has been inserted into said channel and said engagement shoulders have resiliently snapped into said locked position. The or each associated pair of said engagement surfaces and said engagement shoulders may be formed at complementary angles which, in said locked position, are inclined to be nearer to said open end with decreasing distance from a nearer one of said side walls. The or each of said engagement members formed within said channel may include a ramped surface for providing said resilient deflection of said arm member in said width direction during insertion thereof. Preferably, an aperture is formed through said hollow body to provide access to said arm member from the exterior of said hollow body to enable release of said arm member, and more preferably there are a pair of said apertures and a pair of said arm members. In a preferred arrangement, each of said female receptacle member and said male latch member is provided with means for allowing an end of a flexible strap to be secured thereto. A buckle in accordance with the present invention, and a buckle in accordance with the prior art, will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:- Fig. 1 is a perspective view of a buckle of the invention illustrated in a coupled condition and in conjunction with a pair of free ends of a belt or the like; Fig. 2 is a perspective view, similar to Fig. 1, illustrating the buckle in its opened or uncoupled condition and with a portion of the female member broken away and another portion in dotted outline illustrating the interior engagement members thereof; Fig. 3 is a top plan view of the buckle in its coupled condition with a portion of the female member broken away illustrating the connection between the male and female members; Fig. 4 is a side elevational view of the buckle taken along the line 4-4 of Fig. 3 and in the direction indicated generally illustrating the engagement between the male and female members in detail; Fig. 5 is a top plan view of the buckle, similar to Fig. 3, but illustrating release of the male and female members; Fig. 6 is a perspective exploded view of a prior art side release buckle; and Fig. 7 is an enlarged view of a portion of the prior art buckle of Fig. 6 illustrating the engagement and failure positions between the male and female members. Referring to Fig. 1, a buckle of the invention is designated generally by the reference numeral 10. The buckle 10 typically is utilised to connect free ends 12 of webs or flexible straps 14 and 16 and includes a female receptacle member 18 and a complementary male latch member 20. The buckle 10 preferably is formed from plastics material, but the particular material can vary. Additionally, the straps 14 and 16 preferably are connected by threading the free ends 12 through a portion of the respective female and male members 18 and 20, and then sewing the free ends 12 back onto the respective straps 14 and 16. Instead of being sewn, however, the straps 14 and 16 can be connected to the female and/or male members 18 and 20 in an adjustable manner (not illustrated). Referring to Fig. 2, the female receptacle member 18 preferably has a generally flat rectangular hollow cross-sectional configuration having a substantially rectangular shaped interior channel 22 defined by a first top surface or wall 24, a second opposite bottom surface or wall 26 and third and fourth opposite side walls 28. In order to provide the flat or rectangular shape to the female receptacle member 18, the top and bottom surfaces 24 and 26 are wider than the side walls 28. As will be explained in detail below, the male latch member 20 is received and releasably retained within the channel 22 of the female receptacle member 18. To enable access for release of the male latch member 20 from the exterior of the female receptacle member 18 by a user, and assist in retaining the male latch member 20 within the female receptacle member 18, the female receptacle member 18 includes two apertures 30. Each aperture 30 may extend through a portion of the top or bottom surfaces 24 and 26, and preferably extends through both the top and bottom surfaces 24 and 26, as well as through the opposite side walls 28 to form a side-release type buckle 10. It is to be understood, however, that the shape, location, position and number of apertures 30 can vary so long as the buckle 10 operates as described herein. To guide the male latch member 20 as it is inserted into the channel 22 and retain the male latch member 20 therein, two pairs of engagement members 32 are positioned within the channel 22, one pair each on opposite sides of the channel 22. The engagement members 32 in each pair are formed with one engagement member 32 spanning the intersection of the side wall 28 and the top surface 24 and the other engagement member 32 spanning the intersection of the side wall 28 and the bottom surface 26. A gap 34 is provided between the engagement members 32 of each pair for accepting a portion of the male latch member 20 therebetween. To guide and retain the male latch member 20, each engagement member 32 includes a first ramped surface 36, a second sliding surface 38 and a third engagement or locking surface 40. The third locking surface 40 of each engagement member 32 substantially is in alignment with one end of a respective aperture 30. The male latch member 20 preferably includes a base portion 42 having two resiliently flexible arm members 44 formed on opposite ends of the base portion 42 and extending outwardly away from one side of the base portion 42 a predetermined distance. If desired, to assist in insertion of the male latch member 20 within the channel 22, the male latch member 20 can include a guide arm 46 formed between the arm members 44 for complementary engagement with an alignment groove (not illustrated) formed within the channel 22 of the female receptacle member 18. Each arm member 44 includes a first proximal end 48 connected to the base portion 42 and a second opposite distal end 50. To enable sliding co-operation with the engagement members 32 and enable access to a user, the distal end 50 of each arm member 44 is formed with an engagement member 52 which can have a rounded protrusion on its outside surface. To releasably engage the arm members 44 within the female receptacle member 18, each arm member 44 preferably includes a pair of engagement shoulders 54 presented by the engagement member 52 and extending from both a top surface 56 and a bottom surface 58 of the arm members 44. Preferably, to assist in engagement and prevent premature releasing of the male latch member 20 under load, the shoulders 54 are formed at an inclined angle for co-operation with a complementary inclined angle of the third locking surfaces 40 of the engagement members 32 as will be described in detail below. To releasably connect the male latch member 20 to the female receptacle member 18, the second distal end 50 of each arm member 44 first is inserted within an open end of the channel 22. Upon continued insertion, the distal ends 50 will contact the first ramped surface 36 of each engagement member 32 and each arm member 44 will be flexed in a width direction towards the interior of the channel 22. Further insertion provides for the rounded protrusions to ride along the second sliding surface 38 of each engagement member 32 until the rounded protrusions and the shoulders 54 clear the second sliding surfaces 38. At that point, each arm member 44 snaps outward with respect to the channel 22 and, as Figs. 3 and 4 illustrate, the shoulders 54 are seated against the third locking surface 40 of each engagement member 32 and the rounded protrusions of the engagement members 52 extend outward through the apertures 30. As Fig. 5 illustrates, to release the male latch member 20 from the channel 22, a user engages the engagement members 52 and exerts an inward pressure thereon to flex the arms 44 inward with respect to the channel 22. Once the shoulders 54 of the arm members 44 clear the locking surfaces 40 of the engagement members 32 the male latch member 20 can be removed from the channel 22. As described earlier, the prior art buckle 110 illustrated in Figs. 6 and 7 includes a female receptacle member 118 and shoulders 154 located on the outside edges of the arm members 144 of a male latch member 120. Accordingly, the force provided under load is centred along line "A", which runs through the longitudinal centre line or axis of each arm member 144, while the engagement or retaining force provided by the shoulders 154 is centred along line "B", which runs through the shoulders 154 and is slightly offset from the line "A". The offset between lines "A" and "B" produces a torque on the arm members 154 substantially in the direction of arrow "C" in Fig. 7 causing premature breakage of the arm members 144 and/or release of the buckle 110. In contrast, as Fig. 3 illustrates, the buckle 10 of the present invention provides alignment along line "D" of both the load force through the longitudinal centre line or axis of each arm member 44 and the engagement or retaining force provided by the shoulders 54. This alignment of forces, as viewed in the width direction, is possible due to the positioning of the shoulders 54 along the top and bottom surfaces 56 and 58 of the arm members 44 and the co-operation with the third locking surfaces 40 of the engagement members 32. Additionally, when a load separating force is applied to the buckle 10, the co-operation between the shoulders 54 and the third locking surfaces 40 actually causes the arm members 44 to be biased outwardly by virtue of the sliding relationship between the surfaces. More specifically, when a load separating force is applied to the buckle 10 along line "D" outward forces are provided in the direction of arrows "E" in Fig. 3 caused by the shoulders 54 moving slightly down the complementary third locking surfaces 40. The existence of these slight outward forces provides increased holding power of the buckle 10 and prevents premature release.

Claims: A buckle (10) comprising: a female receptacle member (18) having a hollow body defining an interior channel (22) which is open at one end; a male latch member (20) having an arm member (44) which is resiliently deflectable in a width direction during insertion into said channel through said open end of said channel; and latch means (40, 54) formed on said female receptacle member (18) and said male latch member (20) for releasable interlocking engagement upon insertion of said arm member (44) into said channel (22) to a locked position; characterised in that said latch means (40, 54) includes an engagement member (32) formed on a surface of said hollow body facing said channel (22) and an engagement member (52) formed on a surface of said arm member (44) facing in a height direction generally transverse to said width direction. A buckle according to claim 1, characterised in that said hollow body is of generally rectangular cross-section including a top wall (24), a bottom wall (26) and a pair of side walls (28) with the distance separating said top and bottom walls being less than the distance separating said side walls. A buckle according to claim 2, characterised in that said engagement member (32) formed within said channel (22) extends from either said top wall (24) or said bottom wall (26) and presents an engagement surface (40) for abutment in said locked position with an engagement shoulder (54) presented by said engagement member (52) formed on said arm member (44). A buckle according to claim 3, characterised in that said engagement member (52) formed on said arm member (44) has a pair of said engagement shoulders (54) for abutment in said locked position with respective ones of a pair of said engagement surfaces (40) presented by a corresponding pair of said engagement members (32) formed within said channel (22) to extend respectively from said top wall (24) and said bottom wall (26). A buckle according to claim 4, characterised in that said engagement surfaces (40) are separated by a gap (34) which receives part of said arm member (44) after said arm member (44) has been inserted into said channel (22) and said engagement shoulders (54) have resiliently snapped into said locked position. A buckle according to any one of claims 3 to 5, characterised in that the or each associated pair of said engagement surfaces (40) and said engagement shoulders (54) are formed at complementary angles which, in said locked position, are inclined to be nearer to said open end with decreasing distance from a nearer one of said side walls. A buckle according to any one of claims 3 to 6, characterised in that the or each of said engagement members (32) formed within said channel (22) includes a ramped surface (36) for providing said resilient deflection of said arm member (44) in said width direction during insertion thereof. A buckle according to any preceding claim, characterised in that an aperture (30) is formed through said hollow body to provide access to said arm member (44) from the exterior of said hollow body to enable release of said arm member (44). A buckle according to claim 8, characterised in that there are a pair of said apertures (30) and a pair of said arm members (44). A buckle according to any preceding claim, characterised in that each of said female receptacle member (18) and said male latch member (20) is provided with means for allowing an end (12) of a flexible strap (14, 16) to be secured thereto.

Inventors: FRANO FRANCIS G, KELLER STEVEN C, FRANO, FRANCIS G., KELLER, STEVEN C.
Applicants: ILLINOIS TOOL WORKS, ILLINOIS TOOL WORKS INC.
Application year: 1993
Main classification: A44B11
IPC codes: A44B11