GB2586814A - A powertrain with integrated reverse function for use with bicycle flotation systems - Google Patents

Abstract

A powertrain includes a set of rollers, engaged by the rear-wheel of a standard bicycle. The roller assembly is connected to a gearbox below it, through a drive belt, to allow power to be translated to a set of meshing gears. The gearbox permits the user to generate rearward motion of the craft, as a standard bicycle has a ratchet on the rear wheel, prohibiting rearward motion through pedalling. The shifting of the gearbox may be controlled by the user through the use of a lever and a linking cable. A gearless transmission system may be utilised to translate the rotary motion from the gearbox to the propeller along the desired thrust vector.

Description

A POWERTRAIN WITH INTEGRATED REVERSE FUNCTION FOR USE WITH

BICYCLE FLOTATION SYSTEMS

The present invention relates to methods of generating a drive output for bicycle flotation systems.

In particular bicycle flotation systems that permit the use of a standard bicycle to generate the mechanical power to drive the system through regular forward pedalling.

The concept of creating a bicycle-like system that can be ridden on the water is not new. Typically, these products make usc of a fixed bicycle-like structure that the user may pedal in 10 order to travel in a forward direction, or a reverse direction by means of a fixed sprocket. Other concepts utilise a standard bicycle, securely clamped in place, to drive the craft.

The issue with the described bicycle flotation systems that involve an entirely custom bicycle platform, is a large proportion of users may not have space to store them. Furthermore, for 15 platforms that do use a regular bicycle, they have exceedingly complicated and impractical methods of generating power and many do not have the ability to reverse.

The inventor has realised that it is possible to configure a powertrain that aids in significantly reducing time taken to set up the watercraft and embarkation may occur. The powertrain may 20 also incorporate a reverse feature where the user can effectively manoeuvre the craft away from the quay or a nearby hazard.

As such, there is provided a powertrain for use with bicycle flotation systems as defined by the claims.

By powertrain is meant a system that permits energy to be transferred from the source (for example, a bicycle) to a suitable output (for example, a propeller). The thrust provided by the powertrain may be equal and opposite to the user in order to permit motion.

By bicycle flotation system is meant a platfonn which involves a form of flotation, in the way of a raft or pontoons, connected to a frame, connected to a standard bicycle or bicycle-like system. A bicycle-like system preferably contains handlebars, a seat or saddle and some form of generating power, this may come in the form of a pedals or motor.

Embodiments of this invention may be comprised of two rollers which translate the rotational input from the rear bicycle wheel through a gearbox to the propeller. The rollers utilise bevelled sections at either end in order to mitigate lateral movement of the bicycle wheel. Furthermore, additional stabilisers may be used for novices. A set of meshing mitre gears, preferably driven by a belt from the rollers, transform the horizontal input into a vertical output. Alternative methods may make use of gears or a chain to transmit power from the rollers to the mitre gears.

The reverse feature of this gearbox may be engaged through the lateral translation of a toothed collar that engages either free-spinning gear. The position of the collar may be regulated via the use of a thin cable, operated by the rider. This feature permits greater manoeuvrability of the craft while continuously pedalling the bicycle forward. The use of this feature allows the rider to reverse away from a shoreline, following embarkation, or any on-coming hazards. The casing of the gearbox contains several large drainage holes at the bottom so accumulated debris may be flushed out. in order to mitigate damage, a metal skid plate, similar to those found on automotive, may be mounted upon the casing of the gearbox output shaft. This will protect the shaft and propeller in the event of an impact during operation, or when in too shallow water.

In order to convert the vertical gearbox output shaft from the gearbox, into a horizontal drive for the propeller, a gearless transmission system is preferably used. The system may contain four, angled metal rods, that are permitted to slide as the rotational energy is supplied. Due to the nature of this mechanism, it will be easier to maintain than a mitre gear system. Alternative systems may make use of at least two meshing gears to transfer power to the propeller shaft.

For a more detailed understanding of die inventions, reference will now be made, by way of example only, to the accompanying drawings in which: Figure 1 shows an embodiment of the invention in its proposed environment; Figure 2 shows an embodiment of a powertrain in accordance with the invention; Figure 3a to 3e shows a roller assembly for use in an embodiment of the invention; Figure 4a to 4m shows a gearbox for use in an embodiment of the invention; Figure Sato 5e shows a transmission for use in an embodiment of the invention; Figure 6a to 6c shows a protective case for use in an embodiment of the invention; Figure 7a to 7c shows a method of shifting gears for use in an embodiment of the invention; In Figure 1 the depicted embodiment of die powertrain 100 is shown in its intended use upon a bicycle flotation system 70. Struts 102a, 102b are used to secure the invention to the pontoons 104a, 104b. The telescopic clamp 106 may be used to secure a standard bicycle to the flotation system 70, while the rudder 108 may be used for steering of the bicycle flotation system 70 when secured to the front wheel of a standard bicycle. The depicted embodiment of the invention 100 is additionally secured to the main rails 110a, 110b of the bicycle flotation system 70. This is designed to improve the structural stability of the bicycle flotation system 70. Stabilisers 110a, 110b may be used to further prevent excessive lateral motion, in the event the bicycle flotation system 70 is used by a novice.

In reference to Figure 2, powertrain 100 may be composed of a roller assembly 200 (Figure 3a to Figure 3e); a gearbox assembly 300 (figure 4ato Figure 4m); an angled gearless transmission 400 (Figure 5a to Figure 5c) and a protective shaft case 500 (Figure 6a to Figure 6c).

The tubes la, lb, 2a, 2b are used to secure the powertrain 100 to the frame of the bicycle flotation system 70 and are preferably locked in place through the use of spring buttons which may go through holes 202, 12. The benefit of using spring buttons in securing the struts 102a, 102b is enhancing ease of assembly of the embodiment. Alternative securing methods may involve the use of nuts 116 and bolts 112, 114 (Figure 3d), or a bar 118, 122 with a cotter pin 120 (Figure 3e).

The rollers 3,4 within the roller assembly 200 are designed to have the rear wheel of a standard bicycle riding on-top. Accordingly, the flat centre surface of rollers 3,4 may be coated in a grip enhancing material similar to that found on skateboards. The use of a grip enhancing material will aid in ensuring the powertrain 100 may be used while wet, as it will stop slippage of the rear wheel of the bicycle, therefore stopping effective power transfer.

In order to improve ease of maintenance of the system, the cases 10, 11 may be joined together 45 with no partition to allow debris to be washed out easily, without having to disassemble the powertrain 100.

In image 3a it is preferable that lid plates 13a, 13b are used to cover the ends of the rollers 3,4. This may be so that the drive belt at the end of roller 3 is protected, in addition to the protection SO of the roller axles 17a, 17b. in addition to the bevelled edges of the rollers 3, 4 to mitigate lateral movement of the rear bicycle wheel, the plates aid in stopping the bicycle wheel sliding off of the rollers 3, 4.

Contained in Figure 3a, it is dearly shown that roller 3 may differ from roller 4, through the addition of a drive belt pulley. A drive belt may be used to translate rotational motion from the roller 3 down to the gearbox 300. As stated above, a drive belt is the preferred method of S translating this rotary motion, between the roller assembly 200 and the gearbox 300, however alternate methods may include a chain driven system, using a sprocket mounted on shaft 17a; or meshing gears. The benefit of using a drive belt system is, due to the fact that the powertrain 100 is designed for use on the water, it will not corrode and therefore has a longer expected lifetime.

The axles 17a, 17b are preferably secured in the case with nylock nuts 8a, 8b, Sc, 8d. It is preferable to use nylock nuts 8a, 8b, Sc, 8d as they are vibration resistant and will not loosen during regular operation of the bicycle flotation system 70. Alternative methods include the use of cotter pins or circlips, however nylock nuts 8a, 8b, Sc, 8d are preferable due the ease of disassembly and maintenance.

Figures 3b and 3c depict cut away profiles of the rollers 3, 4. Bearings 9b, 9c, 9d, 9e may be mounted within the rollers 3, 4 to reduce the friction of rotation, thus minimising energy lost and making power transfer to the gearbox 300 more efficient. in order to stop lateral movement of the rollers 3,4 upon their respective axles 17a, 17b, the mounted bearings 9b, 9c, 9d, 9e may be clamped between washers 15a, 15b, 15c, 15d, nuts 8a, 8b, 8f, 8g and the tubes I6a, 16b. The tubes 16a, 16b in the depicted embodiment serve to reduce excessive wear upon the inside of the rollers 3, 4.

In Figure 3d and Figure 3e, two alternative methods of securing the struts 102a, 102b and centre tubes 110a 110b may be seen. Figure 3d details how nuts 116c and bolts 114, 116 may be used to secure the struts 102a, 102b and centre tubes 110a, 110b, As illustrated in Figure 3e, bars 118, 122 and cotter pins 120 may alternatively be used, however the use of spring buttons through holes 202, 12 is still preferable.

With reference to Figure 4a, a gearbox 300 may contain a meshing gear assembly 310 (Figure 4d); a method of shifting 320 between forwards and reverse and preferably a pulley 19 to receive rotary motion from the roller assembly 200. A cable 304 may be used by the rider to shift between forward and reverse drive.

The case 302 be constructed out of sheet metal, to provide structure and protection to the gear assembly 310. As depicted in Figure 4b the case 302 may have mounted to it a spring 308 connected to a spring mount 306 and primary cable arm 18. Furthermore, a cable guide 21 may be used to secure the cable 304 to the case. The spring 208 may be used to return the shifting assembly 320 to the forwards position (i.e. position A) once the cable 304 is released.

In the depicted embodiment in Figure 4c, drainage holes 31 may be incorporated into the case. These may be used to permit the escape of water and small debris, in the event that it has entered the powertrain 100. The drainage holes 31 also enable cleaning of the roller assembly 200 and 45 the gearbox 300 and so increasing the life span of this invention.

As detailed in Figure 4b and Figure 4e, the gearbox 300 may contain a shaft seal assembly 330. The shaft seal assembly 330 may be used to stop water leaking down the shaft into the protective shaft casing 500, as this may make the bicycle flotation system 70 unnecessarily heavy during SO operation and when the bicycle flotation system 70 is being lifted out of the water.

In Figure 4d may the meshing gear assembly 310 be seen in the natural forwards position A. The two bearings 9a, 9g secure shaft 32, upon which may preferably be found a drive belt pulley, at least three meshing gears 22, 24, 33, two of which are freely spinning upon the shaft 32 and a toothed shifting collar 23. The shifting collar may be moved to engage with one of the mitre gears either side 22, 24, by way of the cable arm assembly 320 (Figure 4k). The output S gear 33 may be preferably be seated upon a thrust bearing 312. The use of a thrust bearing will improve the efficiency of the gearbox assembly 300 as less energy will be lost to friction.

Figure 4e and Figure 4f illustrate the cable arm assembly 320 and the meshing gear assembly 310 in their secondary, reverse position. This may occur once the rider pulls the cable 304.

Once the cable 304 is released, the cable arm assembly 320 and the toothed shifting collar 23 will return to their natural forwards position.

Figure 4f shows how, when the cable 304 is tensioned, the toothed shifting collar 23 may engage with the reverse gear 22, thus transferring power to the output gear 312 and causing the output 15 gear 312 to rotate in the reverse direction. When the reverse gear 22 is engaged, the forwards gear 24 is therefore disengaged and permitted to spin freely upon the shaft 32.

Figure 4g details how the drive belt pulley 19 and the toothed shifting collar 23 may be Finked with the shaft. The drive belt pulley 19 may be fastened securely through the use of a set screw 314. This is preferable as it is unlikely to come out during operation and may be easily removed in the event of maintenance. The toothed shifting collar 23 may be driven by the shaft, however, is permitted to slid, in order to engage the forwards gear 24 and reverse gear 22. This may be accomplished by way of a key. A split pin key 35 is preferable as it is easier to manufacture and takes up less space inside the toothed shifting collar 23, however, other forms of key may be used.

With reference to Figure 4h and Figure 4i, the tooth profile 36, 37 of the forwards gears 24 and reverse gear 22 as well as that of the toothed shifting collar 23 may be seen. The teeth 36, 37 may be designed with additional empty spacing between so they may engage quickly and easily.

The three-tooth profile is designed to improve the sheer strength of the teeth 36, 37 therefore reducing the likelihood of teeth breaking during regular operation of the bicycle flotation system 70.

Figure 4f of the depicted embodiment of the invention details how the pulley 19 may interface 35 with the free-spinning forwards gear 24. This may be accomplished through the use of a recessed washer 15f. The washer is preferably recessed as otherwise it may push the two pulleys 3, 19 out of alignment.

In Figure 4k it is detailed how the cable arm mechanism 320 may be assembled. The shaft 26 may have flat ends, upon which the primary cable arm 18, and the secondary cable arm 27 arc mounted. The flat ends will mitigate the slipping that may happen if the shaft 26 had round, smooth ends. Alternative methods of securing the primary cable arm 18, and the shifter holder 27 to the shaft, may include set screws or a pin. A cam follower 324 may be secured to the secondary cable ann 27 with a nylock nut 322, to prevent loosening of the cam follower 324 over time. The cam follower 324 rides inside the channel on the toothed shifting collar 23, so that when the cable arm assembly 320 is rotated, the toothed shifting collar 23, will be moved to the desired place.

The primary cable arm 18 and the secondary cable arm 27 are preferably constructed using SO metal 3D printing in order to reduce weight, while maintaining strength. The shaft 26 may be stainless steel so as not to corrode, and the flat ends may be machined to maintain precision.

Figure 41 and Figure 4m depict the shaft seal assembly 330 that may be used to prohibit water and debris from entering the protective shaft case 500. The seal 224 may be secured to the case 302 and the gearbox output shaft 204 with a seal holder 28. The seal holder 28 is designed to be bolted to the case 302 using four bolts, preferably fastened with four nylock nuts 29 to permit easy disassembly and maintenance. The seal holder 28 may be comprised of a strong plastic (That resists getting brittle over time) to help reduce the weight of the drivetrain 100 and therefore improve the portability of the invention.

In the depicted embodiment, Figure 5a details a gearless transmission system 400 that may be used instead of a meshing gear system. The benefit of using a gearless transmission system 400 is there is reduced wear on the system, and so reducing the need for maintenance. As is illustrated in Figure 5a and Figure 5b, the gearbox output shaft 204 is secured into the hub 39b preferably using a bolt, for easy removal during maintenance. The shaft spacers 410, 420 keep the gearless transmission system 400 centred in the protective shaft casing 500.

With reference to Figure 5b, it may be seen that as the upper hub 39b is driven by the gearbox output shaft 204, the power is transferred to the lower hub 39a via the linear movement of the angled bars. As the upper hub 39b rotates, the bars 40 oscillate linearly in each hub 39a, 39b. The power that is translated from the upper hub 39b to the lower hub 39a, may then be used to drive a propeller 7.

Figure Sc shows the arrangement of holes within the hubs 39. It may be preferable as is depicted in this embodiment of the invention that four angled bars 40 are used as the load placed on each bar 40 is reduced. This may reduce the eventuality that the gearless transmission system 400 25 breaks.

Figure 5d and Figure Se illustrate the internal structure of the shaft spacers 410, 420. The upper shaft spacer 410 may contain a bearing 9g which is held in a case 402 to take up the rest of the inside of the protective shaft case 500. The bearing 9g and the ease 402 may rest upon the a washer 15g, to reduce wear between the upper shaft spacer 410 and the upper hub 39b, as well as increasing the efficiency of the system. The lower shaft spacer 420 depicted in Figure 5e may contain and bearing 9h and a shaft seal 38, which may be held in a case 404,4 washer -15h may be used to protect the bearing 9h.

The hubs 39 and the shaft spacers 410, 420 may be composed of nylon due to its self-lubricating nature, which will further reduce need for maintenance. The angled bars 40 may be steel for strength in case of an impact on the propeller that may cause bending.

In Figure 6a, the full assembly of the protective shaft case 500 may be seen. The sealing caps 42 and 43 may be used to stop entry of water into the protective shaft case 500. The scaling cap 43 may be attached to the shaft seal assembly 330 thus mitigating the possibility of water entering the protective shaft case 500 through the hole in the sealing cap 43 for the gearbox output shaft 204.

The skid plate 6 shown in Figure 6b may be used in a similar fashion as those found on the underside of an automobile, as a way to protect the case 5 and propeller 7 from impacts. The skid plate 6 also acts to prohibit the bicycle flotation system from being ridden in water that may be too shallow.

SO in Figure 6c, it may be seen that the case 5 may contain two sections, in the tubular cavity, the gearbox output shaft 204 and gearless transmission system 400 may be permitted to spin freely. In the secondary cavity, there may preferably be foam fitted. The foam will serve as a buoyant aid, while prohibiting water from entering the cavity in case of a leak. The case 5 and the sealing caps 42, 43 may consist of strong plastic that is resistant to brittleness after prolonged use. The skid plate 6 should preferably impact resistant polycarbonate, however, may also be made of stainless steel, in order to be durable, while remaining corrosion free.

For the rider to be able to tension the cable 304 to shift the gearbox 300 into the reverse direction, a shifter assembly 600 may be used as detailed in Figure 7a. In order to be able to attach the shifter assembly 600 to a standard bicycle, two eccentric cam levers may be used. The use of cam levers is preferable as they will decrease the assembly time of the bicycle flotation system 70. The shifting handle 606 may be attached to the shifter assembly 600 through an axle 608 and may be secured in place with a split pin 610. An alternating securing method may involve a nut on a threaded axle. The cable 304 may be fastened to the cable arm 606 so that when the cable arm 606 is rotated to position B, the cable may be pulled forward and thus shifting the gearbox 300 into the reverse direction. Upon release of the shifting handle 606, spring 208 may return the cable ami 18 and the shifting handle 606 to their natural forward position and so recommence the forward motion of the bicycle flotation systcm 70.

In Figure 7b a spacer ring 612a is illustrated about the axle 608 and is sandwiched between the shifting handle 606 and the protective plate 604. As can be seen in figure 7c the spacer rings 20 612 may be used to maintain sufficient space between the protective plate 604 and the main body 616, for the shifter arm 606 to move freely between.

When the eccentric cam levers 602 are closed, the threaded bars 622 are pulled toward the shifter arm 606, pulling the nuts 618 with them and so clamping the top tube of a standard 25 bicycle between the main body 616 and the clamping plate 620.

Claims (1)

1. Claims: 1. A powertrai n for use with bicycle flotation systems comprising means for generating thrust through the engagement of the rear wheel of any standard bicycle, further coupled to a gearbox permitting the forward and reverse propulsion of the hi cycle flotation system. 5 2. The powertrai n of claim 1, wherein thrust may be achieved through the riding of the rear wheel of any standard bicycle upon a set of rollers, which can rotate freely about each of their respective axes.3. The powertrai n of claim 1 or claim 2, wherein the translation of rotary motion from the roller assembly to the gearbox, may be achieved through a form of belt or chain and sprocket system.4. The powertrai n of claim 1, wherein the rotary motion translated from the roller assembly to the gearbox, may be manipulated to provide forward motion defining a forward motion vector, or reverse moti on deli ning a reverse motion vector, of the bicycle flotati on system through the application of a toothed shifting collar, which when moved parallel to the gearbox shaft will engage one of two possible mitre gears and thus induce motion in the desired notion vector.5. The powertrai n of claim 4, wherein the mitre gears engaged by the toothed shifting collar are free spinning upon the gearbox shaft.C7. The powertrai n of any one of claims 4 to 6, wherein the gearbox may be attached to the outside casing of the roller assembly.6. The powertrai n of claim 4 or claims, wherein the lateral translation of the toothed shifting collar upon the gearbox shaft maybe achieved through the use of a cable which the user may operate.CD 30 8. The powertrai n of any one of claims 4 to 7, wherein the gearbox and the roller assembly may C\ be incorporated into a single case.9. The powertrai n of clai ms 4 to 8, wherein the motion of the toothed shifting collar may be induced by a cam follower riding within a channel. 35 10. The powertrai n of clai ms 4 to 9, wherein the motion of the toothed shifting collar may be control led by the user.11. The powertrai n of any preceding claims, wherein the rotary motion is translated from the gearbox to a propeller, through a gearless transmission system.12. The powertrai n of claim 11, wherein the gearless transmission system is comprised of two rotating hubs, in addition to a plurality of angled shafts.13. The powertrai n of claim 11 or claim 12, wherein the shafts may be angled to a minimum of 20°.14. The povvertrai n of clai ms 12 to 13, wherein the shafts may be angled to a maximum of 90°.15. The powertrai n of claim 11 or claim 12, wherein the rotating hubs each contain a mini mum of two holes to permit the reciprocating motion of the angled shafts.16. The powertrai n of clai ms 11 to 15, wherein the gearls transmission system may maintain a central position within the surrounding case, through the application of a plurality of shaft spacers.17. The powertrai n of claim 16, wherein each shaft spacer may be comprised of a bearing, inside a shroud, digned to mai ntai n the al ignment of either shaft entering or exiting the gearless transmission system 18. The powertrai n of claim 16 or claim 17, wherein the shaft spacer used upon the egress of the gearless transmi ssi on system output shaft from the protective casing, may contain a shaft seal, i n order to prevent the ingress of water i nto the protective casing.19. The powertrai n of claim 11, wherein the gearless trarsmi ssi on system is contained within a protective casing that is watertight and spans the distance from the gearbox to the propeller.20. The powertrai n of claim 11 or claim 19, wherein the protective casing is hydrodynarrical ly opti mised to reduce drag on the bicycle floatat on system during operation.21. The powertrai n of any preceding claims, wherein the cable operated by the user, to control the position of the toothed shifting collar may be attached to the standard bicycle used to power the bicycle floatati on system and operated by applyi ng tension to the cable.