Compact drive mechanism for bicycle and reverse trike.
Typically bicycle consists of a frame which facilitates installation of a drive mechanism in the front part which rotates the rear using a shaft or chain drives. These bicycles are big in size which is difficult to use, particularly school going children. Even if we reduce the size, we need to reduce the size of wheels to the extent that it becomes prohibitively difficult cover long distance. We have given compact drive mechanisms for bikes and reverse trikes. It is obvious that reverse trikes are more safe and stable than bikes. More importantly, according to many research articles, reverse trikes have many mechanical advantages over conventional trikes which includes stability, traction in uphills and steerability.
In conventional bicycle and reverse trikes manual force is transmitted to the rear wheel via chain drive or shaft drive using bevel-pinion gear mechanism.
In bicycle rear wheel is pedaled via pedals which are directly connected to the rear wheel hub but we don't get gear ratio.
One of our objectives is to provide compact size bilateral sided drive mechanism to make maximum utilization of manual force on both sides of the bicycle. Drive mechanism consists of two force transmission mechanisms, one on each side of the bicycle.
One of our objective is to allow the ease of use provided by conventional bicycle that is drive mechanism allow the application of manual force via pedals rotation about fixed center.
Objective of this invention is also to provide force transmission mechanism with localized gear ratio and to conceal drive mechanism from the riders clothing.
In order to achieve objectives [05]-[07] drive assembly employs pivoted-slewing-bearing-epicyclic gear (a special type of planetary gear box), with a ratchet ball bearing mounted on one planetary gear, which helps it to facilitate rider to rotate the wheel by the rotation of pedals as described below.
This feature is accomplished by employing pivoted-slewing-bearing-epicyclic gear and a pedal in each drive assembly as described below.
Pivoted-slewing-bearing-epicyclic-gear is a special type of gear in which planetary gears journalled to a carrier plate and a gear ring are arranged in such a way that gear ring can be used as a point of input from manual force via pedal. Gear ring, which is pivoted axially to carrier plate, via a pivot plate, as well as pivoted peripherally, by virtue of being part of an internal toothed slewing bearing, can be rotated via a pedal, which in turn rotates planetary gears along its direction.
One planetary gear, located at rear part of drive assembly, at its center is coaxially connected to an end of the hub of the wheel via one way ratchet ball bearing.
Gear ratio is achieved by the difference in radius of outer ring gear and planetary gear of epicyclic gear. In normal configuration gear ratio is around 2.5.
Drive mechanism doesn't come in contact with clothing of the rider as all its internal parts lie between the pair of carrier plates/pivot plates.
One of our objective is to achieve the driving efficiency comparable to conventional chain driven bicycle.
This objective is achieved due to a feature which maximizes the number of tooth of gear ring gear that is used to rotate the planetary gears.
This feature is accomplished by the appropriately journaling additional gears, apart from planetary and sun gears, to the carrier plate. These additional gears are classified in two categories, one is referred in this patent as satellite gears and the other as far planet gears.
Far planetary gears, of smaller size as compared to planetary gears, are meshingly engaged with gear ring and their sole purpose is to provide additional rotatory force to planetary gears via satellite gears. Satellite gears are meshingly engaged with two adjacent planetary gears and a far planet gears. With this feature loss of manual force is further minimized and efficiency of chain driven drive mechanism is achieved without using chain.
One of our objective is to position the seat towards front half of the rear wheel as preventive measure against rearwardly tipping off of the rider. Since the drive assembly is mounted to rear wheel at its rear planetary gear center of rotation of the pedal is located on the front half of the rear wheel, thereby allowing the seat to be mounted above the front half of the wheel without causing any inconvenience during pedaling.
One of the various objectives is to provide robust wheel support system which, in addition to secure the rear wheel, should facilitate better bike kinematics. This is achieved in the form of backward slanted fork used to secure the rear wheel to the frame.
b Drive assembly front view and exploded back view
As shown in
As shown in [
As shown in [
Drive assembly (DA), as shown in [
As shown in [
Internal toothed slewing bearing (ISB) consist of an internal gear ring (SGR) with internal toothing coaxially mounted on external ring (SOR) and an integrated raceway system rolling elements—balls or cylindrical rollers—that are separated by spacers. In slewing bearing, internal gear ring (SGR) can rotate with outer ring (SOR) fixed along a fixed axis, whilst guaranteeing the axial and radial link between the two parts.
Outer ring (SOR) is preferably flanged.
Three planetary spur gear (P1), (P2), (P3), sun gear (S1), three satellite gears (Sat1), (Sat2), (Sat3) and three far planet gears (FP1), (FP2), (FP3) are journalled to the carrier plate (CP) in an arrangement as explained below.
Sun gear (S1) which is a spur gear is journaled to the center of the carrier plate (CP).
Planetary gears (Px) are spur gears of equal radii, and journalled to carrier plate (CP) such that each of them is meshingly engaged with sun gear (S1) and gear ring (SGR) of the slewing bearing. Centers of planetary gears form an equilateral triangle.
Each satellite gear (Satx) which is a spur gear with radius smaller than that of planetary gears is journalled to the carrier plate such that it is meshingly engaged with two adjacent planetary gears and a far planet gear.
Centers of satellite gear form an equilateral triangle.
Each far planet gear (FP1), (FP2), (FP3) which is a spur gear with radius smaller than that of planetary gears is journalled to the carrier plate such that it is meshingly engaged with gear ring of the said slewing bearing and a satellite gear.
Carrier plate (CP) at its inner side, containing sun gear (51), is attached at its periphery to the outer ring (SOR) of the said slewing bearing over-bridging gear ring (SGR) with the help of U-shaped pegs (UPG) such that slewing bearing is coaxial with Sun gear (S1).
As shown in [
Rear planetary gear of drive assembly is coaxially connected to one end of the hub of the rear wheel (RW) via one way ratchet ball bearing (WRB), shown in [
As shown in [
Internal gear ring (SGR) act as input point and top planetary gears act as output points of drive assembly.
Head tube (HT), as shown [
Top tube (TT), as shown in
Seat (ST) is mounted on the top tube (TT), towards front half of the rear wheel.
Down tube (DT) is a tube attached at its front to the top tube and is connected at its rear end to the fork of drive assembly support system (DAS).
As shown in [
As shown in [
As shown in [
As shown in [
Angle delta between plane of the rear fork (RWS2) and the rear fork support (RWS1) as shown in [
Number | Date | Country | Kind |
---|---|---|---|
201821007903 | Mar 2018 | IN | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/IN2019/050184 | 3/3/2019 | WO | 00 |