AU3646200A

AU3646200A - Constant input leverage transmission assembly

Info

Publication number: AU3646200A
Application number: AU36462/00A
Authority: AU
Inventors: Leonard James Selwood
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-05-28
Filing date: 2000-05-29
Publication date: 2000-11-30

Description

S.

I

AUSTRALIA

Patents Act 1990 COMPLETE

SPECIFICATION

STANDARD PATENT CONSTANT INPUT LEVERAGE TRANSMISSION

ASSEMBLY

The following statement is a full description of this invention, including the best method of performing it known to me: *S S S I S

*S

CONSTANT INPUT LEVERAGE TRANSMISSION ASSEMBLY This invention relates to a mechanical transmission assembly designed to increase the Efficiency of machines using applied linear forces to obtain rotary motion.

Many machines use the principles of a crankshaft to convert linear forces to rotary motion And they can range from pedal powered bicycles to internal combustion engines plus numerous other applications. The dynamics of this method of conversion reveal that the principal of a crankshaft is not very efficient with regard to mechanical advantage.

Applied linear forces when connected to a rotating crankshaft cause a varying quantity Of power to be delivered to the drive shaft because the length of leverage increases and decreases for each angular degree the crank rotates during the application of force.

Additionally the variation in the angles of application of the applied force to the crankshaft contribute to a reduction in the mechanical efficiency of the system.

Another common alternative to convert linear motion to circular motion is the use of a rack and pinion system but with many applications the rigid rack renders it unsuitable and so it is more conunonly used for achieving the opposite effect of converting circular forces to linear forces. Because of the non-varying leverage applied the mechanical efficiency is very high.

This invention uses the rack and pinion system with a flexible rack to provide the reciprocating linear forces to be applied to an unchanging leverage to give a constant flow of •power during the power stroke, providing that the applied force is constant. The flexible 25 rack used in this example of the invention is a roller drive chain and is used with sprockets to transfer the applied linear forces with unchanging leverage into rotary forces at the drive •Shaft.

This invention is very suitable for converting reciprocating linear forces to rotary motion as required more usually by the application of human muscle power. Suitable examples are bicycles, wheelchairs, dynamos, compressors, winches and such. Applied reciprocal forces could also be supplied by pneumatic power, hydraulic power or by slow stroking combustion engines and steam engines.

35 to assist with understanding the invention, reference will now be made to the accompanying drawings which show one example of the invention.

In the drawings: :40 FIG. 1 is a schematic type of drawing using symbolic components to more clearly illustrate the concept of the invention.

FIG. 2 and FIG. 2a show an external full assembly of this example of the invention.

FIG. 3 shows an internal view of this example of the invention.

FIG. 4 and FIG. 4a show an example of an assembly of the components making up the twin drive sprockets, ball bearings and drive shaft assembly.

FIG. 5 and FIG. 5a show an example of the single free wheeling sprocket, ball bearing and shaft assembly.

FIG. 6 and FIG. 6a show an example of the two free wheeling sprockets, ball bearings and shaft assembly.

-1- FIG. 7, FIG.7a and FIG.7b show views of an example comprising the assembly of a single freewheeling sprocket, ball bearing, shaft and bracket assembly with washer and fastener.

Referring to FIG. 1, this example shows a roller drive chain 5, circulating between the assemblies 4, 3, 2 and 1. It will be noted that the drive chain assembly 5 has been terminated at 5a and 5b and replaced with an identical chain transversely rotated 90 degrees to allow that section of roller drive chain to be located around the teeth of sprocket 4a whose shaft has been positioned 90 degrees in relation to the shaft 3c. This allows a more efficient action of the applied forces. 5a and 5b represent the adaptors for realigning the roller drive chain.

The actual design of 5a and 5b is dependant on the device selected to apply the reciprocating forces to the roller drive chain.

Applying a force F vertically downward at 5a sufficient to cause a movement of the roller drive chain assembly 5, then the applied force will cause the roller drive chain to travel in a clockwise direction as shown by the arrows around the sprocket 4a and because the roller drive chain assembly 5 is en endless assembly, any point of the roller drive chain assembly will move a distance equal to the distance that the applied force at 5a moved downwards, therefore the adaptor 5b will move the same amount in an upwards direction as shown by the arrows with a fixed reciprocating action available if required to receive an applied force.

The double freewheeling sprocket assembly 3 allows each alternating movement of the roller drive chain assembly 5 a directed passage to and from the main drive sprocket assembly 2. If the roller drive chain 5 causes 3a to rotate in a clockwise direction, The other freewheeling ~sprocket 3b would rotate in an anticlockwise direction.

At the main double sprocket and drive shaft assembly 2, both segments of the roller drive chain assembly pass around their relevant chain rings 2a and 2b. The chain rings 2a and 2b are fastened to their respective adaptor plates 2c and 2d. The adaptor plates are fastened to their respective hubs 2e and 2f which contain ratchet mechanisms. Both hubs 2e and 2f are fitted positively to the main drive shaft 2g. As shown in this drawing the chain ring 2a will also rotate in a clockwise direction and with the ratchet mechanism in hub 2e arranged to drive positively in the same direction, then the main drive shaft 2g must also rotate in a clockwise direction of rotation with a positive driving action. Chain ring 2b under the same action of the applied force at F will rotate in the opposite direction and because it is reliant on the ratchet of hub 2b which is arranged to freewheel in this direction of rotation with no effect on drive shaft 2g. Therefore the reciprocating application of the forces will allow one chain ring to be driven positively while the other chain ring freewheels but while doing so the freewheeling chain ring rotating in the opposite direction will cause its relevant adaptor bracket to be available for a transfer of force with an immediate response allowing a 40 virtually continuous flow of constantly levered force to be applied to the main drive shaft 2g.

The single freewheeling sprocket assembly 1 is a critical component of the invention because it directs the chain assembly 5 to the chain rings 2a and 2b and to achieve this there must sufficient clearance between the side plates of the roller drive chain 5 and the sides of the the teeth of sprocket la and chain rings 2a and 2b. A slight camber of sprocket la will also facilitate the alignment the of the roller drive chain, the sprocket I a and the chain rings 2a and 2b Another feature of this example of the invention is that, when the mechanism is activated and the main drive shaft is transferring rotary forces to a selected device and then if the reciprocating forces being applied at 5a and 5b are caused to cease then the rotating force of inertia at the drive shaft 2g will continue while the two chain rings will both freewheel.

T o change the driving, rotational direction of the main drive shaft 2g it is only necessary to relocate the main drive shaft with all relevant components of the assembly 2 into its opposite location holes of the casing.

FIG. 2 and FIG. 2a show external views of an example of this invention and the area P is provided as an alternative surface to reposition the component assemblies that receive the applied reciprocating forces. The drive shaft 2g extends outward from the casings 10 and and are available to attach pulleys, sprocket or gears and the like either individually on one side or in unison by using one on each relevantly available location on the shaft. The adaptor brackets 5a and 5b as shown are replaceable with a variety of designs available to suit the applied requirements of the applied forces. The bracket 4b has elongated mounting holes to allow vertical adjustment with thle casing to tension the drive chain assembly FIG.3 shows an internal view of this example of the invention with the casing 10a removed to reveal the layout of the assemblies to obtain a positive applied action for the transferring of forces to the main drive assembly 2. The leverage is constant because the mean effective radius measured between the chain ring 2a teeth and the circular centre of the drive shaft 2g is not variable therefore the leverage is constant.

FIG. 4 and FIG. 4a show details of the main drive assembly 2 as used in this example of the S" the invention. The chain rings 2a and 2b are fastened to their relevant adaptor plates 2c and 2d which are fastened to their respective flanges of the hub assemblies 2e and 2f. The two hub assemblies 2e and 2f are connected to the drive shaft 2g. Each hub assembly contains a •ratchet mechanism that allows the flange of each hub to freewheel in one direction of rotation 25 and to drive with a positive action in the opposite direction, ball bearings 2h and 2i are fitted to the drive shaft 2g and support the main drive assembly 2 by locating in the relevant recesses in casings 10 and FIG. 5 and FIG. 5a Show, in this example of the invention, the assembled components of the single freewheeling sprocket la, ball bearing lc and shaft lb.

a FIG. 6 and FIG. 6a show, in this example of the invention, the assembled components of the double freewheeling sprockets 3a and 3b, each with a ball bearing lc and fitted to shaft 3c.

a a35 FIG. 7 shows, in this example of the invention, the single freewheeling sprocket 4a, "bracket 4b, shaft 4f, spacers 4e, washer 4c and fastener 4d.

Claims

1. A mechanical device that converts reciprocating linear forces with a constant leverage to a rotary force by use of an arrangement of sprocket assemblies and an endless roller drive chain assembly that passes around a single freewheeling sprocket that receives the roller drive chain and then directs the exiting segment of the roller drive chain to its respective chain ring which is part of the main drive assembly and this same chain ring is attached to an adaptor which is attached to a flange of the hub assembly that contains a ratchet mechanism arranged to drive positively in one direction of the roller drive chain travel and transfer the applied force to the attached drive shaft using a turning moment whose non variable radial length is equal to the mean distance from the centre of the circular cross section of the drive shaft to the point of contact between the roller of the drive chain and the contacted surface point of a sprocket tooth receiving the applied force and at the same time the other chain ring which is also part of the main drive assembly will because of its arranged ratchet mechanism free wheel in the direction of rotation of the other segment of roller drive chain which during the same immediate action causes the chain ring to freely revolve in the opposite direction in relation to the other chain ring until the passage of the roller drive chain is reversed and cause the opposite actions to occur with each chain ring because of the endless configuration of the roller drive chain assembly whose opposite looped section encircles another single freewheeling sprocket before having its direction of travel changed by a twin freewheeling sprocket assembly before making contact with the chain rings of the main drive assembly and the actioning forces are applied to the roller drive chain at a suitable position between the final single freewheeling sprocket, bracket, ball bearing and shaft assembly and the twin freewheeling sprockets assembly immediately .~.adjacent

2. A mechanical device that converts reciprocating linear forces with constant leverage to a rotary force of claim 1 wherein a vee belt and vee pulleys are used to transfer the applied force to the main drive shaft in a like manner.

3. A mechanical device that converts reciprocating linear forces with constant leverage to a rotary force of claim 1 wherein a circular sectioned flexible belt and and pulleys are used to transmit the applied forces to the main drive shaft in a like Manner.

4. A mechanical device that converts reciprocating linear forces with constant leverage to a rotary force of claim 1 wherein part or parts of the roller drive chain are replaced by a different flexible drive medium.

A mechanical device that converts reciprocating linear forces with constant leverage to a rotary force of claims 1 to 4 wherein additional double freewheeling sprocket assemblies are used for additional direction changes between the chain rings of the main drive assembly and the double freewheeling sprocket assembly.

6. A mechanical device that converts reciprocating linear forces with constant leverage to rotary force of claims 1 to 5 wherein a frame is structured to replace the casing.

7. A mechanical device that converts reciprocating linear forces with constant leverage to a rotary force as substantially herein described with reference to the accompanying drawings. /I/1t J3 -t AY