BACKGROUND OP THE INVENTION

a. Field of the Invention

The present invention relates generally to portable, low-voltage electrical devices, and, more particularly, to such a device having a hand-wound spring mechanism which generates a supply of power to the electrical load, in place of or in combination with conventional storage batteries.

b. Background

The problems of portable electrical devices, such as flashlights, which use conventional chemical storage batteries are all too well known. Firstly, most conventional batteries are prone to deterioration and leakage, and all have a finite service life. As a result , such a device which has been lef unused for an extended period of time is likely to be rendered useless by weak or corroded batteries at the time when it is most needed.

Moreover, the problem of corrosive deterioration is not limited to the batteries themselves. Conventional storage batteries (e.g., "C" cells, "D" cells, etc.) rely on surface contacts between themselves and with springs and/or metal strips to complete the electrical circuit. Over time, these surface contacts are subject to corroεion (even if they are made of a non-ferrous metal such as copper) ,

especially in a marine climate or other damp environment; ultimately this corrosion will destroy the continuity of the electrical circuit so that the device is rendered inoperative. An additional problem, not directly related to those discussed above, is the cost of having to repeatedly replace conventional storage batteries. Even though more advanced type of batteries have a longer service life than those used in the past, they still need to be replaced on a periodic basis, at considerable expense. Moreover, while this expense may be something of an irritant for people living in industrialized countries, it can be burdensome for persons living in less developed parts of the world. Although a number of hand-operated, "batteryless" flashlights, radios, and other devices have been developed in the past, these have generally proven unsatisfactory in practical use. Many of these prior devices have used a lever or button mechanism which must be squeezed or pressed on a continuous basis to operate a high-speed flywheel which drives a small generator/alternator. This arrangement leaves the operator with only one hand free to do his work. Moreover, the action of the operator's hand--squeezing the lever or pressing the button--makes it virtually impossible to keep the beam of the flashlight steady while working. On the other hand, devices which use a single large storage spring, in the manner of an old "wind-up" phonograph, are excessively bulky and lack sufficient storage capacity/operating time to be satisfactory for truly portable use.

Accordingly, there exists a need for an apparatus which will supply adequate electrical power to a low-

voltage electrical load such ag the bulb of a flashlight or a portable radio receiver without reliance on batteries or other electrical storage cells, and which has an indefinite service life, rather than needing to be replaced on a period basis. Still further, there is a need for such an apparatus in which all electrical contacts are hard-wired so as to be impervious to the affects of long-term corrosion. Still further, there is a need for such an apparatus which does not require actuation by the operator's hands on a continuous basis, so that both hands remain free to accomplish other work.

SUMMARY OF THE INVENTION

The present invention has solved the problems cited above and is a hand-operated apparatus for providing electrical power to a low-voltage electrical load. Broadly, this comprises (a) a plurality of spring modules mounted together in a series so that torque generated by a coil spring in a first module in the series is transmitted from an output end of the spring to an input end of a coil spring in a second module in the series; (b) gear means having an input shaft which is mounted to an output end of the coil spring in the last spring module in the εerieε for rotation thereby as the series of modules unwinds,- (c) an output shaft which is operatively connected to the input shaft from rotation at an increased speed relative to the input sha t; and (d) generator means operatively connected to said gear means for generating the electrical power in response to rotation of the output shaft of the gear means.

Each spring module in the series may comprise

(a) an outer housing; (b) a coil spring disposed annularly within the housing, the coil spring having an output end which is mounted to the outer housing and an input end which is positioned proximate an axial center of the housing; (c) an extension portion mounted to the housing and extending coaxially therefrom for being received at an axial center of a second module in the series; and (d) means for connecting the extension portion from the outer housing of the module to an input end of a coil spring at the axial center of the second module in the series.

The apparatus may further comprise an axle member on which the spring modules in the series are mounted for coaxial rotation. The extension portion of the housing of each spring module may comprise a sleeve portion which extends coaxially from the outer housing and into the center area of the second module, the sleeve portion having a bore for receiving the axle member for rotation thereon.

The gear means may comprise a plurality of gear modules mounted together in a series so that an output shaft of a first gear module in the series is operatively connected to an input shaft of a second gear module in the series. At least one of the plurality of gear modules in the series may comprise an epicyclic gear train.

The generator means may comprise a three-phase generator, or may comprise an alternator or other generator. The apparatus may further comprise governor means for maintaining a rotational speed of the output shaft at or below a predetermined maximum rotational speed.

The low-voltage electrical load may be a portable flashlight bulb, and the apparatus may further comprise a tubular housing member for containing the plurality of spring modules which are mounted on the axle member. The means for manual winding of the spring modules may be a cap member which is mounted for axial rotation on a rearward end of the tubular housing, the cap member having an extension portion which is received in the axial center in the first spring module in the series and is mounted to the input end of the coil spring therein. The means for manual tightening of the spring modules may further comprise ratchet means for limiting

rotation of the cap member to a direction for manual winding of the spring modules . The generator means may be mounted at the forward end of the tubular housing proxi ate the flashlight bulb, and the housing may be sized to permit the apparatus to be carried in a single hand.

Preferably, the coil spring units and gear train units are each constructed as substantially identical modular chambers, so that chambers can be added or deleted on an interchangeable basis as desired.

A switch may be provided which selectively holds the spring-driven mechanism against unwinding until released. One or more electrical storage batteries may be connected to the bulb in combination wich the spring-driven alternator mechanism to supply additional operating time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a spring-driven flashlight constructed in accordance with the present invention, showing the series of modular spring and gear chambers which are contained within the housing thereof for driving the generator which provides electrical power to the bulb of the flashlight;

FIG. 2 is an elevational view of a cross-section taken longitudinally through the flashlight assembly of FIG. 1, showing the modular spring and gear chambers and the electrical generator which these drive;

FIG. 3 is a perspective view of a series of the modular spring chambers mounted on the central shaft which supports these for coaxial rotation during winding and unwinding;

FIG. 4 is an end view of a cross-section taken transversely through one of the modular spring chambers, along line 4-4 in FIG. 2, che other spring chambers being essentially identical to that which is shown in FIG. 4;

FIG. 5 is an end view of a cross-section taken transversely through one of the modular gear chambers, along line 5-5 in FIG. 2, the other gear chambers being essentially identical to that which is shown in FIG. 5;

FIG. 6 is a schematic view of the 3-phase electrical generator- which is a feature of the flashlight assembly of FIGS. ι-2 _;

FIG. 7 is an elevational view of a crosε-section taken longitudinally through the end cap portion of the flashlight assembly of FIGS. 1-2, showing the ball- ratchet mechanism which permits winding of the spring

chambers using the rotatable end cap of the asεembly,- and

FIG. θ is an end view of a cross-section taken transversely through the end cap portion along line β-8 in FIG. '/, showing the arrangement of the ball-ratchet mechanism relative to the longitudinal axis of the hous ng.

DETAILED DESCRIPTION

For purposes of illustration, the present invention will be described herein primarily with reference to a spring-driven flashlight assembly, which is one of the types of portable electrical apparatus to which the invention is eminently suited. It will be understood, nowever, that the modular spring and gear drive system which is used in combination with a compact electrical generator to provide power to a low- voltage electrical load may be employed with a wide variety of other types of portable electrical devices, as will be discussed in greater detail below.

FIG. l thus shows a spring-driven flashlight assembly 10 which illustrates the present invention. This includes a cylindrical case 12 having as size and shape generally similar to that of a conventional hand¬ held flashlight, with a lens 14 (not shown in FIG. 1) at a first end, and an end cap 16 at the other which is rotatable about a longitudinal axis of the case.

The tubular interior of the case holds a series of modular spring chambers 20 and gear chambers 22 which are rotatably mounted along a longitudinal axle member 24 which extends substantially the full length of the case. Each of the spring chambers contains a spiral coil spring 26, with the first spring chamber 20a in the series being connected to the end cap 16. The end cap is retained for rotation on the end of the case on an annular shoulder 17, which is part of the ratchet mechanism which will be described below with reference to FIGS. 7-8.

As the end cap is twisted by the operator in the direction indicated by arrow 27 in FIG. l, the coil

spring in the first chamber is tightened, with the ratchet mechanism preventing the cap from unwinding,- a thumb-actuated switch 2B holds the last spring chamber in the series against rotation by means of a friction clutch or other engagement mechanism, until selectively released by sliding the switch in the direction indicated by the arrow in FIG. 2.

As can be seen in FIG. 3, the input end 29 of the spiral coil spring 26a in the first of the chambers 20a is attached to a sleeve portion 30 which serves as a hub for the end cap 16 on shaft 24, and which extendε coaxially into the center of the first spring chamber. The output end 31 of the first spring 26a, in turn, is attached to the cylindrical outer wall portion 32 of the spring chamber housing 34, which is open at its rearward end- The closed forward end of the housing is formed by a radial flange portion 36 and a forwardly extending sleeve portion 38, which is substantially the same as the sleeve portion of the end cap and supports the chamber for rotation on shaft 24. Low-friction bushings 39 are preferably fitted between the sleeve portions and shaft 2 .

The axial sleeve portion 36 of the first spring chamber 20a extends forwardly into the center area 37 of the next chamber 20b, which is substantially identical to the first. Thus, the inner end of the spring in the second chamber is connected to the sleeve extension from the first chamber, and its outer end is attached to the outer wall portion of the third chamber in line. The torque is thus transmitted through the sleeve portions from one chamber to the next throughout the series .

As is shown in FIG. 3, a series of the identical, "modular" spring chambers described above can be assembled in any suitable number using more or fewer units as desired, depending on such factors as the desired run time, cost, and total case length. In the embodiment which is illustrated, each of the coil springs 26 has a slo (not shown) cut in its end which is engaged by a corresponding lug on he exterior of the sleeve portion of the adjacent spring chamber when the latter is inserted into the center area 37 and rotated, which facilitates simple, economical assembly of the device.

Spiral coil springs are ideally suited for developing torque, and the series arrangement of the chambers enable these to be wound by the operator on an essentially sequential basis rather than all at once, so that a comparatively high torque output can be developed without requiring excessive hand effort. As will be described below, this high torque output is an important factor in achieving the very long run times of which the present invention is capable. In the example which is illustrated, the spring chambers are approximately 1-1/4" in diameter and 5/16" deep, and contain approximately 10-12 turns of a 7mm wide, 0.3-0. mm thick steel coil spring, although these dimensions will vary from embodiment-to-embodiment depending on a variety of design f ctors.

The outer wall portion 32 of the last spring chamber 20e in the series (see FIG. 2) is connected in drive relationship to the cylindrical outer wall portion of the first gear chamber 22a. In the embodiment which is shown in FIGS. 1-2, the outer wall of the first gear chamber is continuous with the outer

wali of the last spring chamber so ae to form a combined chamber unit 40; in other embodiments, however, the wall portions may be separate, with the connection being made by fasteners, couplings, dogs, or other connectors, so that each of these chambers can be substantially identical to the other spring/gear chambers in the series.

The torque generated by the series of spring chambers is transmitted through the connection to the outer wall of the first gear chamber 22a. Aε can be seen in FIG. 4, each gear chamber 22 forms an epicyclic gear train in which the outer wall 42 of the chamber forms an internally-toothed gear which is in engagement with a trio of stationary intermediate gears 44 surrounding a central sun gear 46. As can be seen in FIG. 2 and also in FIG. 1, the stub shafts 48 of the intermediate gears 44 are supported by gear plates 50 which are fixedly mounted to the outer casing 12 of the assembly, so that the intermediate gears are held in stationary position around shaft 24 and sun gear 46. Consequently, as the outer housing of each gear chamber rotates, the intermediate gears drive the sun gear on shaft 24 at a stepped-up rate.

Each sun gear 46 is mounted to the radial flange portion 52 of the next adjacent gear chamber 22, which in turn is mounted to the outer wall internally toothed gear of the chamber. The sun gear of the second chamber is thus driven at a speed which is stepped up by the same ratio as that which is provided by the first. Although the modular gear chambers can be assembled in any number desired (as with the spring chambers described above) , about three such gear chambers having a drive ratio of about 1:6 each, to

13

give a final drive ratio of about 1:216, is a suitable number for many embodiments of the present invention. The gears may be constructed of any suitable material, including metal or molded plastic, for example. Also, in some embodiments of the present invention a simple gear pair (e.g., what is sometimes referred to in the industry as a "servo gear") may be substituted for the final epicyclic gear chamber (or one or more of the others) to provide a lesser or alternate final ratio, as desired.

The sun gear of the final gear chamber is connected axially to a flywheel 53 having a governor mechanism associated therewith. In the embodiment which is illustrated, this is provided by a mechanical governor assembly which is mounted between the flywheel and the last gear chamber. This includes a plurality of movably/pivotally mounted, weighted shoes 54a, 54b which are yieldingly biased in an inward direction

(i.e., towards the rotational axis of the assembly) by tension springs 55a, 55b. When the rotational velocity of the flywheel reaches a predetermined maximum speed, centrifugal force causes the weighted shoes 54a, 54b to move outwardly from the axis so that their outer surfaces 56a, 56b rub against a strip or ring of friction material 57 which is installed around the interior of the cylindrical case 12. This serves to limit the rotational speed of the flywheel to a desired maximum (e.g., approximately 400 RPM in some embodiments) so as to prevent premature unwinding and exhaustion of the spring chambers. It will be understood, however, that other forms of governor mechanisms or constan -speed transmissions known to those skilled in the relevant art may be substituted

for the particular mechanical governor which is shown in this example.

The output side of the flywheel 53 is connected a_xially to the rotor of a small (e.g., l.i amp) electrical generator 58 (or an alternator having internal or associated diodes in some embodiments) at the forward end of the assembly. The output from the generator iε supplied to a conventional flashlight bulb

60 via a positive lead 62. The bulb may be grounded to the case 12, through reflector 64, in the manner of a conventional flashlight, or a separate ground lead 66 may be provided, depending on the use of plastic or other non-conductive materials in the case and drive mechanism. Also, in some embodiments, conventional (preferably rechargeable) storage batteries may be connected to the bulb in conjunction with the leads from the generator, so that these can be used m combination with the generator output to provide an extended period of operation. By using the series of epicyclic gear chambers, a comparatively high shaft speed is achieved at the governor relative to the rate at which the spring chambers uncoil. Put another way, the generator shaft rotates many times for each rotation of the spring chamber assembly. This iε made possible by the comparatively high torque which is produced by the multiple spiral coil springs coupled in series, so that the springs unwind slowly while the shaft speed is maintained high enough for the alternator to operate. The net result is that the apparatus is capable of keeping the bulb 60 lit over a very extended periods as compared with prior devices; for example, the embodiment which is illustrated in FIGS. 1-2 is capable

of operating from about forty minutes to two hours on a single winding, depending on output shaft speed.

As can be seen in FIG. 6, the generator 58 used in the illustrated embodiment of the present invention is preferably a three-phase unit, having output leads "A", "B" and "C", and a neutral lead "N" . Although as was noted above, other types of generators/alternators may be used, this particular configuration has advantages in terms of providing a comparatively high output at relatively low shaft speeds. For example, a three- phase generator of this type constructed to have a size suitable for use in a portable flashlight has been found to provide an output of 3V across each of these output leads, for a total out put of almost 10V at a rotor speed of approximately 400 RPM or approximately 5-6V at 200 RPM. This is sufficient to provide a very strong beam of light or to power a variety of other low voltage loads, while the low shaft speed maximizes the running time for each winding of the assembly; for example, with the output shaft turning at 200 RPM, total run time can be approximately two hours with the embodiment which is illustrated. Also, by switching between the leads the output to the electrical load can be selectively increased or decreased (e.g. , between 3V and 10V in the embodiment which is illustrated) , which is advantageous for certain applications; for example, by switching to full output, a brighter beam of light can be generated by the flashlight assembly, as may be needed from time -to-time, and then at other times the assembly can be left at the lower output setting for longer bulb life.

FIGS. 7 and 8 show the ratchet mechanism which permits winding of the spring chambers using the end

cap 16. As can be seen, this employs a ball-ratchet mechanism in which there are a plurality of individual ball members 70a, 70b, 70c located in pockets 72a, 72b, 72c which are spaced apart angularly around an annular shoulder 74 on the end of the housing 12. Each of the pockets includes a semi-spherical cup portion 76 which accommodates the ball member in rolling engagement therewith (see FIG. 8) , and a ramp portion 78 which leads into this at a generally tangential angle. The upper portions of the ball members 70 are received, in turn, are received in and engage an annular channel 80 which is formed in the inner surface of the cap member, as shown in FIG. 7.

Accordingly, the assembly permits the cap member 16 to be rotated relative to the cylindrical housing in the proper direction for winding of the spring chambers, as indicated by arrows 82 in FIG. 8, with the ball members acting as ball bearings and providing a very smooth and durable action. As soon as the direction of rotation is reversed, however, the ball members back or ride up the ramp portions 78 of the sockets so as to "jam" between the casing and the cap member, locking the two together. This provides a "ratchet" action which is very quick and positive, requiring only a small fraction of a turn of the cap in order to engage.

This mechanism has numerous advantages over traditional spring- loaded pawl mechanisms, in terms of economy of manufacture, ease of use, and durability (no pawl or spring to break) , and a very positive action even after much use and wear. Moreover, unlike conventional spring-loaded pawl mechanisms, operation of the ball-ratchet mechanism shown in FIGS. 7-8 is

completely silent, which is of particular benefit when the device is used for military and/or police operations. It will be understood, however, that in some embodiments of the present invention, a spring-loaded pawl or other form of ratchet mechanism may be employed in place of the ball-ratchet mechanism which has been shown, if desired.

Aε was noted above, the combination of modular spring chambers to store the energy and provide a high torque output, gear units to step the output up to the desired shaft speed, and a generator or alternator attached to the output shaft, forms a basic "power pack" which may be used to provide electrical power to loads other than the bulb of a hand-held flashlight . For example, the present invention may be configured to supply electricity to the more powerful bulb of a stationary lantern, or to any number of non-lighting devices, such aε hand-carried emergency radio beacon transmitters, portable radios, fans, cellular telephones, and laptop computers, to provide just a few examples .

Accordingly, it is to be recognized that these and various other alterations, modifications, and/or additions may be introduced into the constructions and arrangements of parts described above without departing from the spirit or ambit of the present invention as defined by the appended claims.