Tailcap insert

Abstract: The flashlight having a conductive barrel (22) and a tailcap insert (10) which provides for enhanced mechanical and electrical contact between the barrel (22) and the batteries (56), provides for retaining a tailcap spring (28) to the tailcap (24) upon removal of the tailcap (24) from the barrel (22), provides retainers (16) to prevent the tailcap insert contacts (14) from over radial extension and/or provides a one-way flow seal (40) to permit outflow of gases produced during flashlight operation but to prevent ingress of material from ambient to within the battery housing.

Description: The present invention relates primarily to flashlight improvements and, in particular, to hand-held flashlights having a tailcap insert of the type generally disclosed in US Patent No 4 819 141 and/or to a flashlight having an improved seal to permit flow of out gases from the interior of the flashlight to ambient while preventing ingress of foreign material into the flashlight battery compartment. Flashlights of varying sizes, shapes and power supplied are well-known, including flashlights having a tailcap insert of the type shown in US Patent No 4 819 141. In general, such flashlights incorporate inserts of this general type in order to eliminate several machining steps during manufacture of the flashlight and to maintain a high degree of electrical continuity within the electrical circuit in the tailcap region of the flashlight. It has been observed that with known tailcap inserts of the type shown in US Patent No 4 819 141, the lateral forces exerted on wings of the insert are sometimes insufficient to exert a tight mechanical fit between the wings and the inside surface of the barrel at the tailcap end of the flashlight. Also, it has been found that the indents in such a tailcap insert did not always provide for secure holding of the spare lamp which is normally kept within the central bore of the tailcap. Also, the tailcap inserts of the general type disclosed in US Patent No 4 819 141 may permit the tailcap spring to become loose, upon removal of the tailcap from the barrel during battery and/or lamp replacement. Conventional flashlights are also known to produce gases during normal operation of their enclosed batteries. One of the problems associated with conventional flashlights is inadequate provision for the flashlight to permit release of excess gases produced during the normal operation of the flashlight. Although many conventional flashlights are effectively sealed through the combination of close mechanical tolerances at closure points and through strategically placed O-rings or equivalent seals, such seals effectively prevent not only ingress of contaminants, but also prevent escape of gases produced during normal operation of the flashlight, and therefore may permit undesirable gas build-up within the flashlight battery compartment. GB-A-2 021 306 discloses a waterproof flashlight in accordance with the pre-characterising portion of claim 1, in which the partial pressure of hydrogen within the housing is controlled by providing a microporous membrane across a vent in the housing. This allows hydrogen to diffuse out of the housing but prevents water ingress. US-A-4 433 366 discloses an underwater swimming pool light which includes a one-way valve so that steam created by water leakage into the housing can be vented out. The present invention seeks to provide an improved flashlight. According to the present invention, there is provided a flashlight comprising: a battery housing forming a closed internal volume having a passage extending to atmosphere from said closed internal volume, the passage being closed by means allowing gas to exit the housing; a lamp bulb; an electrical circuit extending from said battery housing to said lamp bulb; characterised in that said means is a one-way valve in said passage oriented to permit gas flow from said closed internal volume to atmosphere. Thus, the invention can provide a hand-held flashlight having a one-way seal which permits the outflow of gases from the interior of the flashlight battery compartment to ambient but which prevents ingress of foreign materials into the battery compartment of the flashlight. The one-way flow seal may be made of a flexible material of a generally donut shaped configuration, but having a rearwardly facing channel and an inner wall and outer wall and placed at the interface between the tailcap and barrel whereby gases contained within the battery compartment of the flashlight may be passed out through the seal but ingress of foreign materials through the seal and into the body of the flashlight is prevented. The seal feature also includes one or more vents positioned at the interface between the barrel and tailcap The invention will be further described by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a foreshortened, front perspective view of the tailcap insert of the present invention. Figure 2 is a rear perspective view of the one-way flow seal of the present invention. Figure 3 is a cross-sectional view of the tailcap end of a flashlight incorporating the present invention, taken along lines A-A and, in pertinent part, B-B of the tailcap insert of Figure 1 and the one-way flow seal of the present invention. Figure 4 is a cross-sectional view of the Figure 1 tailcap insert. Figure 5 is a rear view of a preferred tailcap incorporating the presently disclosed invention. Figure 6 is a side view illustrating alternate gas vents of the present invention. Figure 7 is a front view of the tailcap insert of Figure 1. Detailed Description of Preferred Embodiments In flashlights of the general type shown in US Patents Nos 4 577 263 and 4 658 336, advantageous use is made of a tailcap insert of the general type shown in US Patent No 4 819 141. Although the present invention may be used with virtually any size and type of flashlight, the following description relates to uses in flashlights of the type set forth in the above-referenced patents. Referring to Figures 1 and 3, a tailcap insert 10 is shown. The tailcap insert 10 has a generally tubular shaped body 11 having a longitudinal slot 12 formed along one side of its length and a plurality of contact leaves 14 and spring retainers 17 at its forward end. The slot functions to provide ease of manufacturing from a single, thin, sheet of material and to provide for variable closing radii in order to place the insert 10 into the central bore of the tailcap 24. The contact leaves 14 function to provide an electrically conductive path between the battery 56 and barrel 22 of a metal flashlight. The tailcap insert 10 of the present invention may be made of any suitable conventional conductive material, such as for example, beryllium copper, or other materials which provide good electrical conductivity as well as good mechanical strength. Referring to Figure 2, a rear perspective view of the one-way flow seal 40 of the present invention is shown. Inner channel 44 extends into the body of the generally donut shaped 40 seal and channel 44 has a radially outer wall 52 and a radially inner wall 54. The channel outer wall 52 together with its adjacent region forms flexible portion 42 of the one-way flow seal 40, as will hereinafter described more fully. The channel 44 is shown facing to the tailcap; however, it is noted that an important feature of the channel is that it faces away from the battery compartment. In a preferred embodiment, the tailcap insert 10 has two contact leaves 14, 14 as shown in Figures 1, 3 and 4. Each contact leaf 14 extends from the main body portion of the tailcap insert 10 first inwardly at contact leaf lamp retainer portions 38, 38 and then outwardly and forwardly at wing portion 56. The mutually opposed contact leaf lamp retainer portions 38, 38 will, upon insertion of the tailcap assembly into a barrel having batteries, cause a force to be applied against spare lamp 50 sufficient to securely contain the lamp within the central cavity of the tailcap 24. The main portion, or wings, of the contact leaves 14, 14 then extend forwardly and radially outward to a predetermined maximum radial distance from the tailcap central bore centerline and its distal end portions 15 then curve in towards the central bore centerline to terminate at contact leaf retainer fingers 16, 16. Each contact leaf 14 has two contact leaf retainer fingers 16, 16 at its distal end. The contact leaf retainer fingers 16, 16 butt up against the inside surface of tailcap counterbore 48, as shown in Figure 3 and thus prevent radial extension of the contact leaves 14, 14 beyond a predetermined radial distance from the centerline. In this regard, overextension is to be avoided due to the possibility of an adverse bending force which might be otherwise applied to a contact leaf 14 and damage or break it. In addition to the two contact leaves 14, 14 at the forward end of the tailcap insert 10, four spring retainer leaves 17 are provided. As shown in Figures 1, 3 and 4, a total of four spring retainers 17 are provided for the tailcap insert 10 and each spring retainer leaf 17 comprises a lower leg 18 and an upper leg 20. Referring to Figure 3 the tailcap end of barrel 22 is shown having barrel counterbore 36, a portion of a battery 56, a tailcap 24, and tailcap insert 10. Also, shown in compression, is conventional conical tailcap spring 28, one-way flow seal 40, lanyard hole 26, and vent slot 46. Although a conical spring is preferred, and shown in Figure 3, other types and shapes of springs may be used, such as for example, a straight, tubular spring, as long as the spring performs its function of exerting spring force between the battery and the tailcap to force the batteries forward and the insert wings radially outward. In its assembled condition, as shown in Figure 3, the tailcap 24 screws into the tail end of barrel 22 at barrel threads 30 and tailcap threads 32. As further shown in Figure 3, the compressive force exerted on spring 28 by the action of battery 56 and tailcap 24 applies force downward against the inner surface of wing portion 56 of each contact leaf 14, thus forcing its radially outermost portion into a tight mechanical fit up against the inner surface of the barrel 22 at barrel counterbore 36, and thus forming an electrical contact of enhanced certainty and reliability. Also, as shown in Figure 3, each contact leaf 14 lamp retainer portion 38 then also exerts a radially directed inward force against lamp 50 which is positioned within the central cavity of tailcap 24 to thus further secure the spare lamp. Also shown in cross-section in Figure 3 is the one-way flow seal 40. As described hereinabove in regard to Figure 2, the Figure 3 cross-sectional view shows one-way seal 40 having a flexible portion 42 at its outer periphery and an open channel 44 extending away from the battery compartment, the channel 44 also having channel outer wall 52 and channel inner wall 54. Also shown in Figure 3 is vent 46 cut in the tailcap and adjacent to and immediately rearward of the seal flexible portion 42. When assembled, the seal 40 rests against the shoulder 58 and the face 60 of the tailcap 24. The one-way seal of the present invention replaces the conventional O-ring located at the tailcap end of a conventional flashlight. Although it is preferred that the one-way flow seal of the present invention be placed in the tailcap region of the flashlight to provide a one-way seal between the inside and outside of the flashlight battery compartment, it is envisioned that a seal of the present invention could be located at another location, such as, for example, at the head region of the flashlight in order to provide equivalent outgassing and prevention of contaminant ingress. Also, although the one-way seal is disclosed in conjunction with flashlights of the type generally having AA sized batteries or smaller, such as AAA or AAAA, the one-way seal of the present invention may be usefully employed in flashlights using virtually any size and type of battery, specifically such as C and D-cell sizes. As may be appreciated, the one-way flow seal of the present invention is preferably of a plastic or flexible material having sufficient flexibility to enable the seal flexible portion 42 to extend radially inward upon a predetermined over pressure condition within the battery housing to permit outgassing to occur, and to respond to any pressures generated by foreign material, whether solid, liquid or gaseous, entering vent 52 and applying pressure radially outward from within channel 44. The one-way seal of the present invention may be made, for example, with buna-n, natural or synthetic rubber, or other known materials used in the manufacture of O-rings or conventional seals. It is also noted that, depending upon the type of battery used in the flashlight, the particular nature of the outgas produced during battery operation may influence the choice of material of construction used in the seal, so that adverse chemical reactions are prevented. Referring to Figure 4, a cross-sectional view of the Figure 1 preferred embodiment tailcap insert clearly illustrates the wing portion 56 and the distal ends 15 of each leaf 14, showing the upward and radially extending outward direction of wing portion 56. Behind and radially within wing portion 56 is shown the contact leaf lamp retainer portion 38 and also extending in a forward direction from the forward end of the main body 11 of the tailcap insert 10 are shown two of the spring retainer leaves 17. Referring to Figure 4, the slightly bent shape of the spring retainer leaves 17 formed by the lower legs 18 and upper legs 20 enable the conical tailcap spring 28 to be slipped around the plurality of contact leaf retainers 17 and then down to and flush with the inside surface of the wing portion 56 of contact leaf 14. Upon removal of the tailcap from the barrel, the spring retainer leaves 17 exert a slight force radially outward from the tailcap insert centerline, to thus apply a retaining force against the lower, or rearward coils of the coil spring 28, as shown, for example, in cross-sectional view Figure 3. Upon insertion of the tailcap, the spring 28 forces the wing portion 56 against the barrel 22. Figure 5 shows a rear view of the preferred tail cap 24 incorporating the presently disclosed invention. Other views of the external features of this tailcap may be seen in Figures 14-15 of U.S. Patent No. 4,819,141, which is herein incorporated by reference in its entirety. Figure 6 illustrates alternate forms of the gas vent feature of the present invention, whereby a plurality of sawtooth shaped vents 46, 46' are positioned around the entire circumference of the end of the barrel 22 and the tailcap 24. Although in Figure 6 the vents 46, 46' are shown fashioned on the barrel 22 and the tailcap 24, such vents could also conveniently be formed on the only tailcap itself as is preferred. Also, if the seal were placed at the head end of the barrel, the vents would be placed on the head of the barrel or at an appropriate location at the head region of the flashlight. Although a plurality of vents are shown, virtually any number will work, so long as there is at least one vent having an orifice dimension sufficient to permit flow of outgases from the interior of the battery housing to ambient. Referring to Figure 6, preferred and alternate vents are shown at 46, 46', it being understood that it is preferred to place vents only on one component, such as either the tailcap, 46 or on the barrel, 46'. Although the exact pressure, gas production rate and identity will vary from flashlight to flashlight and battery type to battery type, the gas discharge values are believed to be relatively small relative to the ability of a metal flashlight to contain pressure build up. Also, it is noted that the one-way flow seal of the present invention may be employed in not only conventional, dry-cell, non-rechargeable battery flashlights, but also in flashlights with rechargeable batteries. Referring to Figure 7, a front view of the tailcap insert 10 of the present invention, the four contact leaf upper fingers 20, the two contact leaves 14 and wing portions 56, and the double, mutually opposed contact leaf retainer fingers 16 are shown to illustrate their respective radial positioning. As the tailcap assembly is rotated into the tailcap end of the barrel 22 it may be seen that the outermost edge 56 of the contact leaf 14 is forced radially outward, that is upward and downward as shown in Figure 7, to enhance mechanical and therefore electrical contact between the tailcap insert 10 and the inside of the barrel 22 at counterbore 36. Also, it may be observed that upon placement of coil spring 28 on the tailcap insert 10, the four spring retainer leaves 17 would be initally compressed radially inward and, thereafter their inherent resiliency would provide a force radially outward, to thereby retain the spring on the tailcap during normal usage. Again referring to Figure 7, the double, mutually opposed contact leaf retainer portions 16 maybe seen to retain the wing portions 56 of contact leaf 14 from moving radially outward, that is upward and downward in Figure 7, when the tailcap 24 is removed from the tailcap end of the barrel 22. In further reference to Figure 7 and Figure 3 it may be seen that these portions 38 butt up against tailcap counterbore 48.

Claims: A flashlight comprising: a battery housing (22) forming a closed internal volume having a passage extending to atmosphere from said closed internal volume, the passage being closed by means (40) allowing gas to exit the housing; a lamp bulb; an electrical circuit (14,22,28) extending from said battery housing (22) to said lamp bulb; characterised in that said means (40) is a one-way valve (40) in said passage oriented to permit gas flow from said closed internal volume to atmosphere. A flashlight according to claim 1, wherein the battery housing (22) has a first opening (36) and a closure (24) for said first opening (36) of said battery housing (22) wherein said passage is between said closure and said battery housing. A flashlight according to claim 2, wherein said closure is a tailcap (24) mounted by threads (30,32) to said battery housing (22). A flashlight according to claim 1, wherein said one-way valve (40) is a seal ring having a flexible flange (42) extending to seal against a side of said passage and inclined away from said internal volume in said passage.

Inventors: MAGLICA ANTHONY, MAGLICA, ANTHONY
Applicants: MAG INSTR INC, MAG INSTRUMENT INC.
Application year: 1990
Main classification: F21V31
IPC codes: F21V31, F21L4, F21L19, H01M2, F16J15