Method and apparatus for minimizing battery corrosive electrolyte leakage

Battery corrosive electrolyte leakage is reduced by absorbing forces generated during impact of a device holding the batteries and preventing such forces from being transferred to terminal contacts of batteries held in a series configuration. Contacts of batteries connected in series are protected by use of shock absorbing spacers while a terminal end shock absorber is positioned so that the terminal end will be cushioned when a force is applied to the series configuration causing the batteries to move relative to the terminal battery.

FIELD OF THE INVENTION

The present invention is in the field of minimizing battery corrosive electrolyte leakage from devices that use batteries, including alkaline and rechargeable batteries, and is especially concerned with minimizing battery corrosive electrolyte leakage in portable, hand-held devices, one example of which is a flashlight, which use batteries held in a battery compartment in an in series arrangement.

BACKGROUND OF THE INVENTION

Batteries of all sizes and types, including chargeable and non-rechargeable, are used in a variety of devices to provide power to electrical circuits.

Alkaline batteries have provided power to consumer and hand-held devices, one example of which is a flashlight, for decades. A general description of the construction of alkaline batteries is described in the prior art, an example of which is the article found at http://www.electrical4u.com/alkaline-batteries, as well as a technical bulletin about Duracell® batteries found at http://ww2.duracell.com/en-US/Global-Technical-Content-Library/Technical-Bulletins.ispx, both of which are incorporated by reference herein, from whichFIG. 1and the following description of such construction is obtained. The body of a battery, generally designated as100, is made of a hollow steel can102comprised of an outer cylindrical wall1020C, a top surface102TC and a bottom surface102BC. Can102contains all materials of the battery. A positive cap with a nipple103of battery100is projected from the top of can102. A manganese dioxide cathode powder mix104is pressed against the inner steel wall of can102so that the steel case of the can becomes the cathode current collector and serves as the positive terminal of the cell. The inner surface of the thick layer of cathode mixture is covered with a porous separator105which isolates the electrodes of the battery. The central space, inside separator105, is filled by a zinc anode powder106. The porous nature of the anode, cathode, and separator materials allows them to be thoroughly saturated with the alkaline electrolyte solution. A metallic pin107is welded to the external anode cap111and extends through a plastic cap or grommet109into the center of the anode powder mix maintaining intimate contact. This pin is called a negative collector pin or an anode current collector. Plastic cap or grommet109is sealed to the steel can102by means of radial crimping pressure and a sealant. Anode cap111is electrically isolated from the positive cell case102with an insulator110. A vent mechanism112is incorporated into the plastic grommet109to protect against cell rupture. An outer insulative wrapping102W is also commonly applied to can102which is also used to contain printed material, such as trademarks and trade dress of the battery manufacturer.

Batteries, including alkaline batteries, are often aligned in series, in which a positive terminal of one battery is in direct contact with a negative terminal of another battery. Using a flashlight as an example, it is well known in the prior art to include a battery compartment, such as a barrel, in which batteries (such as AAA, AA, C or D cell size) are aligned in series. While such an arrangement is the common and traditional arrangement, there have been prior suggestions that steps be taken to protect battery electrodes in a series arrangement where two batteries connect with each other, such as through the use of a battery spacer and resilient conductor as taught in U.S. Pat. Nos. 5,645,955 and 5,795,675.

However, despite the fact that batteries, including alkaline batteries, have been used in a variety of devices for decades, there has been a well-known problem that batteries can leak battery corrosive electrolyte over time, causing problems related to cleaning such leaks and sometimes ruining a device in which the leak occurs.

Accordingly, the present invention addresses a long-felt need for a way to minimize battery corrosive electrolyte leaks in devices that use batteries, including but not limited to, flashlights.

SUMMARY OF THE INVENTION

The present invention is generally directed to reducing battery corrosive electrolyte leak by absorbing forces generated during impact of a device holding the batteries and preventing such forces from being transferred to terminal contacts of batteries held in a series configuration. Contacts of batteries connected in series are protected by use of shock absorbing spacers while electrical contact is maintained by resilient contacts (which can be integrally held by the shock absorbing spacers) and a terminal end shock absorber is positioned so that the terminal end will be cushioned by the terminal end shock absorber when a force is applied to the series configuration causing the batteries to move relative to the terminal battery holder.

When the device in which batteries are being used is a flashlight, a two-piece tail cap can be used, an inner member of which is driven by an outer member, and tail caps of existing flashlights can be replaced so that a strong tall cap spring no longer provides a biasing means against the terminal contact of the terminal battery.

Accordingly, it is a primary object of the present invention to minimize battery corrosive electrolyte leakage in devices in which batteries are held in a series configuration.

This and further objects and advantages will be apparent to those skilled in the art in connection with the drawings and the detailed description of the invention set forth below.

DETAILED DESCRIPTION OF THE INVENTION

In the Figures and the following detailed description, numerals indicate various physical components, elements or assemblies, with like numerals referring to like features throughout both the drawings and the description. Although the Figures are described in greater detail below, the following is a glossary of elements identified in the Figures.1flashlight2shock absorbing spacer11barrel of flashlight111T thread of barrel1112head of flashlight113light source of flashlight114tail cap of flashlight120shock absorbing spacer assembly22resilient contact22H hole in resilient contact2222GH guide hole in resilient contact2231curling arm of resilient contact2232ear of resilient contact2240spring41lock ring42lip seal51outer member of tail cap52thread of member5153knurl54F female spline55spring contact57central bore61inner member of tail cap62thread of member6164M male spline65battery can engaging surface100battery100(1) first of two batteries in a series configuration100(2) second of two batteries in a series configuration102can1026C bottom surface of can1021020C outer cylindrical wall of can102102TC top surface of can102102W battery wrap103positive cap with nipple104cathode powder105porous separator106anode powder107negative collector pin or anode current collector109plastic cap or grommet110electrical insulator111anode cap112vent mechanism202shock absorbing material301modified shock absorbing spacer302spring303tail cap

Generally speaking, when two or more cylindrical batteries are held in a series configuration in a battery compartment, a top surface of each of the batteries has a nipple contact while the bottom surface of each of the batteries has a generally flat surface, and the top nipple contact is traditionally a positive or cathode contact while the bottom flat contact is traditionally a negative or anode contact. The battery compartment which holds the batteries in a series configuration traditionally has a top contact against which a first battery in the series is loaded and a compression spring that serves both as an electrical contact for the last battery in the series (hereinafter the terminal battery) and as a biasing means so as to keep the batteries in series held in electrical contact by biasing the bottom flat contact of the terminal battery toward the top contact.

While the present invention is not limited to use with flashlights, and is applicable to any device with a battery compartment in which two or more batteries are held in a series configuration, the present invention will hereinafter be described and illustrated, for ease of understanding, by reference to only one specific device—a flashlight, examples of which are described in U.S. Pat. Nos. 6,361,183 and 8,366,290, the disclosures of which are specifically incorporated by reference herein.

In a flashlight1the terminal battery is the last battery which is inserted into barrel11of the flashlight and the terminal battery is biased toward head12of the flashlight, which contains light source12, by a compression spring included in a tail cap14which seals off the barrel after the batteries have been inserted and the tail cap is screwed on and into place.

While it is traditionally the case that the bottom flat contact of a first battery in a series configuration (which is inserted into a flashlight barrel before the next or second battery in a series configuration) is in both physical and electrical contact with a top nipple contact of the second battery in the series configuration, in accordance with one aspect of the present invention, such physical contact is prevented by a shock absorbing spacer inserted between the first and the second batteries in the series configuration.

In an especially preferred embodiment of the present invention, a shock absorbing spacer2is configured as a disc which has a circular outer cross section which is of substantially the same diameter as the diameter of the two cylindrical batteries it is inserted between and an inner cross section which is of substantially the same diameter as that of the bottom surface102BC of the first battery and/or the top surface102TC of the second battery. It is especially preferred that shock absorbing spacer2have a thickness sufficient so as to keep the top nipple contact of the second battery in the series configuration from coming into contact with the bottom flat contact of the first battery in the series configuration, even when the flashlight is subjected to extreme shock, such as, for example, being dropped from a distance of several meters, or more. Accordingly, the thickness of the shock absorbing spacer should be greater than the height of the nipple of the top nipple contact, and take into account variations in such height in various batteries, as well as any compression of the shock absorbing spacer when it is performing its shock absorbing function under anticipated or desired performance criteria. The shock absorbing spacer can be made of any material that absorbs shock, such as energy-absorbing plastic or rubber, and it is especially preferred that the material be a cushioning material that absorbs a proportion of the kinetic energy arising when the flashlight suffers impact or is dropped, while still having sufficient recovery that the shock absorbing spacer will continue to function over time.

Because shock absorbing spacer2keeps the top nipple contact of the second battery in the series configuration100(2) from coming into contact with the bottom flat contact of the first battery in the series configuration100(1), the two terminals must be electrically connected, and, in an especially preferred embodiment of the present invention, this is done by at least one resilient contact held by the shock absorbing spacer in a shock absorbing spacer assembly20, and the electrical contact with the top nipple contact is made with the base below the nipple, or outer diameter of the nipple (less preferably), but not the top surface of the nipple, as illustrated inFIG. 25in which shock absorbing spacer2has a thickness of Y whereas the distance between the top nipple contact of the second battery100(2) and the bottom flat contact of the first battery100(1) is X. The reason it is especially preferred that the at least one resilient contact not contact the top of the nipple is that reliance on such contact would mean that shock absorbing spacer2would need to be thicker so that a shock would not allow energy to be passed from the nipple through the resilient contact to the bottom flat contact.

The at least one resilient contact can take on many different forms, some preferred embodiments of which are illustrated inFIGS. 4, 8, 12, 16, 18, 20 and 22.

InFIG. 4, resilient contact22is formed from stamped metal with a plurality of holes22H, two guide holes22GH, and a curling arm31. Two mirror imaged contacts22are mounted opposite of each other (seeFIG. 3), with their holes22H and guide holes22GH aligned, and then shock absorbing spacer2is molded so that its material fills holes22H but leaves guide holes22GH unfilled, for later use in assembly, to form shock absorbing spacer assembly20.

InFIGS. 8, 12 and 16, a single resilient contact22is formed from stamped metal, but multiple ears32are bent in opposing directions as illustrated inFIGS. 7, 11 and 15, respectively, and the ears of the different embodiments have different configurations. A shock absorbing spacer2is molded around the single resilient contacts22to form the different embodiments of shock absorbing spacer assembly20illustrated inFIGS. 6, 10 and 14.

In additional embodiments, resilient contact22can be a spring, examples of shapes of which are illustrated inFIGS. 18, 20 and 22, and such springs can be secured within shock absorbing spacer2by molding to form shock absorbing spacer assemblies as illustrated inFIGS. 19, 21 and 23, respectively.

Shock absorbing spacer assemblies20can easily be dropped in between batteries as batteries are being loaded into a barrel11of a flashlight1; one shock absorbing spacer assembly should be inserted between every two batteries; accordingly, a flashlight having two batteries in series will use one shock absorbing spacer assembly between the two batteries; a flashlight having three batteries in series will use two shock absorbing spacer assemblies between the first and second, and the second and third batteries; a flashlight having four batteries in series will use three shock absorbing spacer assemblies between the first and second, the second and third, and the third and fourth batteries, and so on, so that the number of shock absorbing spacer assemblies used in a barrel will equal one less than the number of batteries arranged in a series configuration. In view of the ease of such assembly, it is easy to see why it is especially preferred that shock absorbing spacer2and resilient contact22form a single assembly; however, resilient contact22could also be detached from shock absorbing spacer to accomplish the same functional purpose, albeit with the need for a more difficult assembly process.

Use of shock absorbing spacer assemblies20between two batteries in a series arrangement allows energy imparted during a shock to be absorbed by the shock absorbing spacer assemblies and also imparts substantially all of the shock between bottom surface102BC of can102of the first battery and top surface102TC of can102of the second battery in a series arrangement, rather than imparting shock to either bottom flat contact111of the first battery or top nipple contact103of the second battery.

In another aspect of the present invention, a terminal end shock absorber is positioned so that the terminal end of a terminal battery in a series configuration will be cushioned by the terminal end shock absorber when a force is applied to the series configuration causing the two or more cylindrical batteries to move toward a terminal retaining member (which is a tail cap15in flashlight1).

In some situations, it may be possible to use a shock absorbing spacer20as a terminal shock absorber, depending upon how electrical contact is made with a tail cap, how the tail cap fits into a closed electrical circuit, and how much space there is between bottom flat contact111of the terminal battery and its contact point within the tail cap. In an especially preferred embodiment of the present invention, a specially designed tail cap assembly is used to provide a terminal end shock absorber.

Because many different devices make contact with the terminal end of a terminal battery in different ways, even in one device category, such as a flashlight, it is worth noting that sometimes a strong spring is used to make such contact; however, if one is designing a particular device, especially where cylindrical batteries are inserted into a cylindrical tube, one way to minimize the amount of stress that might be applied to the terminal end of the terminal battery is to insure a snug fit so there is less room for the batteries to move in the event of extreme shock.

One of the reasons why batteries may not enjoy a snug fit is variations in tolerance and production specifications/actual manufactured dimensions of batteries. As more batteries are aligned in a series configuration, there is a greater possibility of cumulative variations. In accordance with one aspect of the present invention, a snug fit is created by the combination of eliminating variations between pairs of batteries with a spacer (which can either be a shock absorbing spacer, as already disclosed, or a non-shock absorbing spacer having the same construction except for the use of a non-shock absorbing material) and then insuring a snug fit by creating a snug mechanical fit at the bottom surface of the can of the terminal battery. Use of spacers between adjoining battery terminals helps cancel variations in dimensions of the batteries because variations in positive cap103or anode cap111are no longer important since the spacer is held between bottom surface102BS of the first battery and top surface102TC of the second battery, and the width of the spacer is greater than the nipple of positive cap103. Accordingly, when a snug fit is created at bottom surface1028of the terminal battery, that snug fit will ensure that the cans of the batteries in the series configuration, with spacers between each pair of batteries, create a solid continuous length of material in which no meaningful force is applied to the battery terminals between two adjoining batteries while the terminal end of the terminal battery is retained at its can, rather than at its anode cap.

One especially preferred embodiment of a device which creates a snug fit for the terminal end of a terminal battery is a mechanical contact that can be tightened against the bottom surface102of the terminal battery until a snug fit is obtained, and one example of such a device is disclosed inFIGS. 26-32, which is especially useful for the device category of a flashlight, in which a two piece tail cap is provided in which an inner member61of the tail cap50can be driven by an outer member51of tail cap50to screw into flashlight barrel threads11T so that bottom surface102BC of the terminal battery is held snugly by battery can engaging surface65of inner member61as illustrated inFIG. 33. In this especially preferred embodiment, mating splines are used to illustrate one mechanical driving mechanism; however, this embodiment is meant to be illustrative, rather than limiting, and any other suitable driving mechanism could also be used in alternative embodiments within the scope of the present invention. Returning toFIG. 33, inner member61is driven by engaging female splines54F in outer member51of tail cap50with male splines64M of inner member61and then using outer member51to screw inner member61into position; once inner member61is fully screwed into position, female splines54F and64M are disengaged and threads52of outer member51are then screwed into flashlight barrel threads11T to secure outer member51to barrel11as illustrated inFIG. 34. It is especially useful if a lock ring41is used to secure outer member51(which has a lip seal42) to inner member61(seeFIGS. 33 and 34); inner member61and lock ring41can be designed so that lock ring41will not be removable once it is in place or so that it can be removable with a certain amount of force. Because the two piece construction of tail cap50allows battery can engaging surface65to snugly hold bottom surface102BC of the terminal battery (and it is especially preferred that battery can engaging surface65engage all or substantially all of bottom surface102BC, but not anode cap111), an electrically conductive spring40may or may not be required, depending upon whether bottom surface102BC is insulated, such as by a battery wrap102W; but, even if it is required, conductive spring40need not be a strongly compressed spring and can have a minimum contact force (of around 200 grams or 0.44 lbs.)—just enough to ensure electrical contact, but not so much that it will provide a mechanism for imparting a damaging force to the terminal end of the terminal battery in the event of extreme shock. (Springs used in tail caps of prior art flashlights to create a biasing means forcing the batteries toward the top contact could have a much higher contact force, on the order of 10 lbs. or more.) Spring40, as illustrated inFIG. 33, can be secured by spring contact55.

One way of minimizing any potential damaging force that spring40might impart to the terminal end of the terminal battery in the event of extreme shock is to minimize its length and strength.FIGS. 35-41illustrate an alternative embodiment of a two piece tail cap in which a central bore57in which spring40is held is minimized so that a shorter spring can be used for ensuring electrical contact between the terminal end of the terminal battery and the tail cap.

The two piece tail cap construction described so far can also be used in devices that utilize rechargeable battery packs, an example of which is a NiMH battery for the Mag Charger® LED flashlight. In such a device, multiple rechargeable batteries are wrapped together in a snug casing, which is electrically insulating, so the terminal end of the terminal battery extends out of the casing, and a button end of a first battery also extends out of the casing, but the other ends of the batteries held in series are held tightly together inside of the battery wrap. In such a device, while shock absorbing spacers2might be used inside of the casing when the battery pack is manufactured, it is not possible to use shock absorbing spacers2with existing battery packs without destroying the battery wrap, which is not desirable; however, the two piece tail cap construction already described will still prove useful with such battery packs.

The two piece tail cap construction already described can also be modified to provide a shock absorbing spacer202that makes contact with bottom surface102BC of the terminal battery, andFIGS. 35-38illustrate one example of how such a shock absorbing spacer can be provided. In this especially preferred embodiment, shock absorbing spacer202is held or mounted to inner member61of tail cap50, shock absorbing spacer202is configured to absorb a primary impact force imparted between it and bottom surface102BC of can102, and shock absorbing material202may be similar or identical to that used in shock absorbing spacer2. Such construction is also especially preferred for use with rechargeable battery packs that do not utilize shock absorbing spacers between batteries contained with the battery packs.

Because there are millions of flashlights already in use, it is also desirable to provide a kit and method by which such existing flashlights can benefit from the teachings of the present invention.

As already noted, flashlights in use today typically have a compression spring that serves both as an electrical contact for the terminal battery and as a biasing means so as to keep the batteries in series held in electrical contact by biasing the bottom flat contact of the terminal battery toward the top contact. This means that the compression spring is usually fairly strong, and it exerts a strong compressive force against bottom flat contact111of the terminal battery (not just to maintain electrical contact, but also to keep the batteries biased toward the top contact); however, when the battery receives a shock, movement of the batteries against the strong compression spring causes the spring to further compress, applying even greater compression force against bottom flat contact111. By contrast, the present invention seeks to minimize the compressive force applied against bottom flat contact111of the terminal battery and to rely upon a terminal end shock absorber to both absorb some shock as well as transfer energy through bottom surface102BC of can102of the terminal battery, rather than through bottom flat contact111.

One way a flashlight can be retrofitted with a terminal end shock absorber in accordance with the present invention is to replace an existing tail cap assembly with its compression spring with a new tail cap assembly200such as is illustrated inFIGS. 39 and 40. Replacement tail cap assembly200utilizes a shock absorbing material202, a tail cap resilient contact201and a tail cap203. Shock absorbing material202is configured to absorb a primary impact force imparted between it and bottom surface102BC of can102of the terminal battery while the tail cap resilient contact is configured to absorb a secondary impact force imparted between it and the flat contact of the terminal battery, wherein the secondary impact force is substantially less than the primary impact force. While tail cap resilient contact201might be configured similarly to resilient contact22, it may also be configured as a small compression spring, which may be more suitable for use in a replacement kit in which all of the components of the flashlight have not been designed so as to take advantage of use of one or more shock absorbing spacer assemblies and a terminal end shock absorber. Shock absorbing material202may be similar or identical to that used in shock absorbing spacer2.

An alternative embodiment to that shown inFIGS. 39 and 40is to utilize a shock absorbing spacer2, as already disclosed, which is modified as illustrated inFIGS. 41 and 42. In this embodiment, the contacts with the terminal end of the terminal battery (or the terminal end of a rechargeable battery pack) of modified spacer301remain the same as already described, but the other contacts are replaced with a spring302which makes electrical contact with tail cap303.

While the invention has been described herein with reference to certain preferred embodiments, those embodiments have been presented by way of example only, and not to limit the scope of the invention. Additional embodiments will be obvious to those skilled in the art having the benefit of this detailed description. For example, because the terminal end shock absorber does not need to separate two terminals of batteries in series, but a terminal end of a terminal battery from a tail cap, the terminal end shock absorber might be constructed to provide shock absorption through mechanical means, or means other than using a shock absorbing material similar to that of shock absorbing spacer2; thus, for example, a tail cap might be designed to include one or more mechanical pistons that compress air within one or more enclosed spaces with appropriate pressure relief.

Accordingly, still further changes and modifications in the actual concepts descried herein can readily be made without departing from the spirit and scope of the disclosed inventions as defined by the following claims.