CA2305881A1

CA2305881A1 - Variable speed transmission

Info

Publication number: CA2305881A1
Application number: CA 2305881
Authority: CA
Inventors: Noel Lamoureux
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-04-19
Filing date: 2000-04-19
Publication date: 2001-10-19

Abstract

The evolution in the sphere of bicycle transmission is scant. From the beginning of the single speed driving spocket - driven spocket - and chain combination, the nearly one hundred year old Sturmey-Archer and the "derailleur" type of 1922 are the only transmission innovations to be accepted by the buying customer.
The single speed transmission is evidently limited to flat or nearly flat country operation. The Sturmey-Archer planetary system, in the driven wheel hub, is limited to three and five speed ratios, limiting its hilly country operation. The "derailleur" type, using banks of ordinary sprocket gears on the driving and driven ends has a good range of available ratios.
However, it suffers from, A/ sharp misalignment of the driving chain in some of the chosen ratios, resulting in the chain skipping engagement and creating shocks, B/ required frequent maintenance of the cable operating system, lack of which may also creates the aforementioned problem.
Furthermore, study of all the available ratios on the "derailler" type of transmission shows that, only approximately half of the available ratios, when combining multiple gears in driving and driven wheel assemblies, generate a gradually usable range of speed and torque application. Another study, through observation of ordinary cyclist rallyes involving thousands of participants, showed an average of eighty per cent of competitors using the wrong ratio, leg muscles overworked or, uselessly revolving legs, pointing to the need of a simpler and better performing mechanical system.
Study of available submissions on innovating transmission systems ( excepting the three already mentioned ) with manual operation or automatic changing of ratios, revealed some or all of the following shortcomings : cost of installed unit incompatible with normal bicycle retail prices -complicated mechanical and fragile elements - weather sensitive - complicated maintenance and repairs.
The following specification, on the submitted variable speed transmission, addresses these desirable qualities, cited by priorities : fabrication cost and retail price compatible with the cheapest selling bicycles - simple mechanical parts and assemblies - easily repaired -maintenance-free - fully automatic and weatherproof.

Description

sheet 3 of 18 -----------CAVEAT
SPECIFICATION
I, LAMOUREUX Noel do hereby declare this invention to be described in the following statement The invention relates to a speed changing device, in general, and to a variable speed transmission unit suitable for bicycle installation or, any other machine requiring a change of speed automatically responding to change of torque application, in particular.
The object of this invention is to provide a variable speed transmission mechanism that can be used in connection with any type of belts or mechanical chains alike without any effect on its efI'lciency. Another object of the invention is to provide a variable speed transmission mechanism that can be used indifferently with a single speed driving spocket - or pulley - in combination with a variable speed driven sprocket - or pulley - or, a variable speed driving sprocket - or pulley - in combination with a single speed driven sprocket - or pulley - and finally, with a variable speed driving sprocket - or pulley - in combination with a variable speed driven sprocket - or pulley.
A still further object of the invention is, to provide a variable speed transmission unit in which loss of chain or belt tension, chain or belt wear, chain or belt jumping are reduced to a minimum and /or, prevented. Hence, long life for the assembly.
The basic complete assembly consist of : a driving wheel - a driven wheel -connecting chain or, belt - an automatic tension adjuster ( said adjuster is to be any of the commercially available units), as per general figure AA on sheet 6. The retracting/expanding variable speed driving gear or pulley, consist of one { 1 ) hub - two (2) or more pivoting links attached to hub - two (2) or more pivoting segments attached to outboard end of links. Independantly moving link/segment assemblies are interconnected by springs and movement controllers/dampers.
This sequence of assembly is repeated for the driven expanding/contracting variable speed gear or, pulley..
The above mentioned and other advantages of the invention, will be better understood with reference to the following description and drawings contained in figures 1 to 12 in which {Note : all necessary antileak seals and weatherproofing scraper/cleaner seals, miscellaneous paraphernalia deemed unnecessary for patent application, are omitted for drawing clarification.) r ~i~~~'lli,~B'~ i Specification, continued on sheet 4 Sheet 4 of 18 FIGURE 1 : (sheet 7) - shows the driving sprocket/pulley, consisting of a hub, two (2) or more pivoting links (four shown as exemple), two or more pivoting segments. Figure lA
shows the sprocket/pulley in the extended idle position. Figure 1B shows the sprocket/pulley in the retracted position after applying torque/rotation on the hub/link assembly, against resistance/load applied to the segment = low speed..
Each link / segment assembly is independent, in order for each segment to independantly concur/synchronise itself with the chain/belt pitch at each rotation.
FIGURE 2 : (sheet 8) shows coil springs installed between each link/segment assemblies, maintaining driving sprocket/pulley in the extended position, at idle or light load configuration. Springs can be of any available configuration, coiled, torsion for exemples, following weight and /or positioning consideration. Figures 2A
and 2B showing accordingly, an extended and retracted position, same as Figure 1.
FIGURE 3 : (sheet 9) shows movement-controller/dampers installed between link/segment assemblies, working in conjunction with previously mentioned springs.
Following field testing, the assembly at the stage shown in figure 2 is not practical or viable per se. With the single use of springs, as each link/segment assembly is released from the chain/belt load during loaded rotation, the link/segment assembly jumps out, to be reinserted again under chain/belt pressure, with a different radius to hub, creating shocks sensed throughout torque application, preventing smooth and regular variation of diameter and speed.
The movement controller/damper positively does that : eliminates harsh movements created by loading/unloading springs. The movement controller/dampers are fully explained in subsequent Figures 7 to 12.
FIGURES 4 -:5 -6 : (sheets 10 - 11 - 12) shows configuration of the driven sprocket/pulley assembly, which follows the same principle as the driving sprocket/pulley assembly, except in reverse : traction/rotation is applied on segments against resistance/load from hub, resulting in expansion of wheel, higher speed Note : Springs and dampers are shown separately for drawing clarification purposes only. Actual assembly may use combined spring/damper setup, inbuilt springs in dampers, springs and dampers installed on different sides of the main assembly. Whatever is dictated by requirements such as, ease of assembly - weight - maintenance - weatherproofing.
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Specification continued on sheet 5 Sheet 5 of 18 FIGURE 7 : (sheet 13) shows a basic, movement controller/damper unit, consisting of only a combined piston and rod moving in an enclosed cylinder, filled with constant viscosity fluid to be within the temperature range required for each designed type of operation, e.g. : -40 to +40 C. Each side of the piston are chambers of absolutely exact volume. The flow of fluid moving from one chamber to the other is metered by a designed gap measurement between piston O.D. and cylinder wall.
Gap dimension to suit speed and load performance required, when moving the link/segment assemblies under increased or decreased torque application.
FIGURE 8 : (sheet 14) shows another version of Figure 7 piston/cylinder assembly. This one uses asymetric chambers each side of the piston. To compensate for dissimilar volumes, a free sliding piston/seal is inserted on the main piston rod side, with fluid on one side and air accross.
FIGURE 9 : (sheet 15) shows another version of Figure 7 unit. This unit uses low clearance fit or ring sealed piston/cylinder wall gap and a cylinder wall inbuilt bypass circuit, with a metering valve for hand adjustment purposes of system.
FIGURE 10 : (sheet 16) shows four (4) views, A - B - C and D describing four different types of piston/rod assembly to accommodate four different types of performance.
Item A : control of the fluid movement by the piston/cylinder gap (ref. Fig.
7) Item B : control of the fluid movement by metering holes in piston proper.
Item C : control of the fluid movement by the size and material caracteristics of a commercially available "O" ring installed on piston.
Item D : control and transfer of the fluid by a selected size piston rod cavity and piston/seal combination FIGURES 11 : (sheet 17) shows another fluid transfer arrangement, consisting of one (1) piston/rod assembly to which is added a secondary piston, both with seals. A
built-in protusion inside the cylinder divides a chamber, between pistons, in two symetrical volumes. Control of fluid transfer principle, to be similar to either Figure 7 , 9 or 10, by dimension of gap between piston/rod and cylinder protusion ~~'~r~ G~'/ ~ a Specification continued on sheet 6 Sheet 6 Of 18 FIGURE 13 : (sheet 18) shows a two-way differential flow valve that can be inserted either way in transfer conduit shown in Figure 9, in pistonlrod assemblies shown in Figure 10, Views B and D and an accommodating cylinder protusion in Figure 11. This valve can be installed should a different flow speed be deemed necessary, between contraction and expansion actions of wheels diameter. Pressure from "A" pushes needle valve against spring, fluid flows through and around needle for up to maximum flow allowed by design towards "C". Pressure from "C" butts the needle against the stop, limiting flow towards "A" through the aperture in needle.
Furthermore, this principle of contracting/expanding driving gear/pulley, and vice versa for the driven gear/pulley, with spring action controlled by dampers, can be applied to power driven {engine, motor) machineries or, vehicles. Beginning with the smaller gear/pulley in the driving mode in lieu of driven, already existing free or, proprietery technologies in clutches, torque converters, fluid control systems and electronic controls can readily be adapted, to the driving gear/pulley. The simple damper system described can become outside source fed from both ends of the cylinder, electronically controlled, thus activating the progressive contraction/expansion actions of .the dampers, in both the driving and driven gear/pulley modes. In some cases, source fed dampers, pressurised or unpressurised, may eliminate the need for between link/segment springs.
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Specification (Figures) continued on sheets 7 to 18

Claims

A VARIABLE SPEED TRANSMISSION

1 - A variable speed transmission mechanism, consisting of a driving sprocket, gear or, pulley, with alternating contracting and expanding motions, a driven sprocket, gear or, pulley with alternating expanding and contraction motions, interconnected by any type mechanical chain or, belt without any effect on its efficiency, with controlled chain or, belt tension by any type mechanical or, hydraulic tensioner, for use on bicycle installation or, light tool or, machinery.

2 - A driving sprocket, gear or pulley, comprising one hub, two or more links attached to, and pivoting on hub, two or more segments, adapted to type of chain or, belt required, attached to, and pivoting on links.

3 - A driven sprocket, gear or pulley, comprising one hub, two or more links attached to, and pivoting on hub, two or more segments, adapted to chain or, belt required, attached to and, pivoting on links

4 - A required number of any type compression springs to, at any required location, interconnect all adjacent link/segment assemblies together in the driving sprocket, gear or, pulley assembly.

Variable Speed Transmission-Claims-- A required number of any type extension springs to, at any required location, interconnect all adjacent link/segment assemblies together in the driven sprocket, gear or, pulley assembly.

6 - On both driving and driven sprockets, gears or pulleys, a required number of any type spring-movement-dampers to, at any required location, interconnect all adjacent link/segment assemblies in both the driving and, driven sprockets, gears or, pulleys, as the required key item controlling acceptable operation of all assemblies as detailed in items 1 to 5.

7 - For automotive type application, a basically similar type of automatic transmission as defined in claims 1 to 6 above, except for the following differences which are, comprising a driving sprocket, gear or pulley with one hub, two or more links, two or more segments, with (contrary to item 1) alternating expanding and contracting motions, a driven sprocket, gear or pulley with one hub, two or more links, two or more segments, with (contrary to item 1) alternating contracting and expanding motions, without interconnecting springs, and with movement-controlling-dampers replaced by electronically controlled any type hydraulic actuators, at any required location, controlling and synchronizing movement of, link/segment assemblies with each other, in driving and driven sprocket, gear or, pulley assemblies and with any type chain or, belt required.