FIELD OF THE INVENTION
The present invention relates to an improved freewheel for bicycles. More
particularly, this invention relates to an improved freewheel assembly wherein
the inner ball bearing system of conventional freewheel is replaced by a pair of
polyamide or nylon rings.
10
BACKGROUND OF THE INVENTION
A freewheel of a bicycle is driven by a chain drive through a free-sprocket. The
free-sprocket is coupled to freewheel by a connector with a tooth. When the
15 free-sprocket rotates clockwise, the tooth of the connector is forced into
engagement with the tooth of the free-sprocket, and therefore the connector
with the freewheel hub and freewheel are turned in the same direction. When
the free-sprocket is rotated counter-clockwise, the teeth of the free-sprocket are
moved over the tooth of the connector. Therefore, the connector allows the
20 rotating drum to turn freely in the counterclockwise direction. The normal
operating mode for a bicycle's freewheel is clockwise rotation wherein it takes
with it the body and the wheel together. When the pedals are stopped, it permits
the body and the wheel to turn continuously (freewheeling) until friction stops it.
25 The conventional freewheels are assembled on the rear driving wheel of bicycles.
The freewheel mechanism comprises an inner body integral with the wheel hub
and an outer body carrying the chain drive sprockets of the bicycle, pedal-driven,
said outer body being assembled rolling on the inner body through two sets of
ball bearings, positioned circumferentially, housed in suitable seats of the two
30 bodies. It is also known that, for good operation of freewheels, it is very
important to have the ball bearings in good condition or functioning in a precise
• 3
5 way. Therefore, regular oiling and greasing is required for proper functioning of
freewheel assembly.
Freewheels are used to advance the bicycle freely without any rotation of the
pedals. There are different types of Freewheels which include boss type
10 freewheels that are mounted on the boss of the rear hub by being screwed onto
the rear hub, and free-hub type freewheels which are fastened to the rear hub as
an integral part of the rear hub. Both types of freewheels are equipped with an
outer tubular part, an inner tubular part which is installed radically inward of the
outer tubular part so that the inner tubular part is free to rotate relative to the
15 outer cylinder part. Due to heavy load and continuous motion, the inner tubular
part always requires maintenance and thus is not economical for long run.
The purpose of this invention is to eliminate the above mentioned drawbacks
and to provide a freewheel with easy and at the same time, very economical,
20 with substantial improvements in the quality of the device as compared to those
disclosed in the prior art.
OBJECT OF THE INVENTION
It is an object of the present invention to eliminate the above-discussed
25 disadvantages inherent to the conventional devices.
Another object of this invention is to provide an improved bicycle freewheel
which is simpler in construction and with lesser number of components, thereby
permitting a lower manufacturing cost.
30
Yet another object of this invention is to provide an improved bicycle freewheel
with a long life span without affecting its performance.
• 4
5 Yet another object of this invention is to provide an improved freewheel
mechanism obviating use of conventional ball bearing system.
Yet another object of this invention is to provide an improved freewheel which
10 has a simple structure and is easy to assemble so that assembly efforts and
manufacturing expenses are reduced.
Still another object of this invention is to provide an improved freewheel which
runs at low noise.
15
SUMMARY OF THE INVENTION
This invention relates to an improved freewheel of bicycles and its mechanism
where the metallic ball bearing is replaced by nylon or polyamide rings.
20
Accordingly, the first aspect of the present invention comprises an inner
freewheel body (Centre Ring) and an outer freewheel body (Lock Ring). The inner
freewheel body includes a simple taper for housing a nylon ring on a rear wheel
chain ring. Lock Ring or Outer Ring is used to lock the entire assembly of Centre
25 Ring, Pawls, Springs, Nylon Rings and Chain Ring together in its place. Therefore,
an outer ring and a center ring coaxially mounted on chain ring having a pair of
nylon rings are assembled in such a way so as to form a rotatable coupling
freewheel of a bicycle. Hence, the new design does not uses hardened steel balls,
and only the chain ring of the freewheel of the present invention need to be
30 hardened thus decreasing the manufacturing cost as well as environmental
pollution.
• 5
5 In accordance with another aspect of the present invention, a pair of polyamide
or nylon ring of inner part and outer part of the freewheel are movably formed in
between centre ring and chain ring part at a location of the inner periphery of
the ring element, the spring elements, and the internal pawls. A pair of pawls and
at least one spring per pawl have been disposed between inner and outer
10 freewheel bodies whereby forward rotation of the outer freewheel body causes
pawls to engage and drive the inner freewheel body and rear wheel. The pawls
allow the rear wheel to rotate in clockwise direction when the outer freewheel
body is rotating more slowly or has been stopped.
15 In accordance with another aspect of the present invention, a freewheel
assembly is provided that includes a freewheel for a bicycle, comprising an inner
freewheel body having a first inner section with a first diameter and a second
inner section with a second diameter that is smaller than the said first diameter,
the first section having a nylon ring. An outer freewheel body ring concentrically
20 arranged about the inner freewheel body for relative rotational movement there
between. The outer freewheel body has a first outer section with a third
diameter and a second outer section with a fourth diameter that is smaller than
the said third diameter, the first outer section has an abutment stopper
extending outwardly therefrom in a radial direction. A pair of nylon rings is
25 located between inner and outer freewheel body surfaces in a first circular
pattern.
These and other objects, features, aspects and advantages of the present
invention will become apparent to those skilled in the art from the following
30 detailed description, which, taken in conjunction with the drawings, discloses
preferred embodiments of the present invention.
• 6
5 BRIEF DESCRIPTION OF THE DRAWINGS
A complete understanding of the system and method of the present invention
may be obtained by reference to the following drawings:
FIG. 1 shows an exploded view of a conventional freewheel;
10 FIG. 2 shows an exploded view of the freewheel of the present invention;
FIG. 3 shows a cross-sectional exploded view of a conventional freewheel;
FIG.4 shows a cross-sectional view of the freewheel of the present invention;
FIGS. S & 6 show a diagrammatic difference between a conventional freewheel
with ball races for hardened steel balls and the new design with a simple taper to
15 house the nylon rings.
FIG. 7 shows a cross-sectional view of a conventional freewheel with a set of 104
hardened steel balls;
FIG. 8 shows a cross-sectional view of new freewheel design with taper housing a
pair of nylon rings of the present invention;
20 FIG. 9 shows a conventional Centre Ring with Ball Races;
FIG.10 shows a new Centre Ring Design without the Ball Races and with a simple
Taper of the present invention;
FIG.ll shows a conventional chain ring;
FIG.12 shows a new chain ring without ball races of the present invention;
25 FIG.13 shows a conventional outer ring;
FIG.14 shows a new outer ring with taper of the present invention;
FIG.1S shows a freewheel pawl;
FIG.16 shows a freewheel spring;
FIG.17 shows a conventional hardened steel ball; and
30 FIG.18 shows a nylon ring of the present invention.
• 7
5 Accordingly, in a preferred embodiment of the present invention is disclosed a
freewheel assembly for attachment between a wheel and a transmission device
of a bicycle comprising an inner freewheel centre ring (2) having a first inner
section with a first diameter and a second inner section with a second diameter
that is smaller than the said first diameter, the first section having a ring (10), a
10 taper (11) formed at one side of the said centre ring (2), and a pair of pawls (4)
provide locking of the chain ring 1 through the springs (5); a chain ring (1)
mounted over the centre ring (2) of the freewheel having taper (llA) formed at
inner periphery of the said chain ring (1); and an outer freewheel lock ring (3)
having a first outer section with a third diameter and a second outer section with
15 a fourth diameter that is smaller than the said third diameter, the first outer
section having a ring (10), and a taper (11) formed at one side of the centre ring
(2) for the engagement with chain ring (1); wherein: the said outer freewheel
lock ring (3), and centre ring (2) are coaxially mounted on the said chain ring (1)
having tapers (11, 11, 11A) on centre ring (2), lock ring (3) and chain ring (1)
20 respectively for positioning of a pair of the said rings 10.
In another embodiment of the present invention the said rings (10) are made
from polyamide, nylon, or similar material known in the state of the art.
25 In another embodiment of the present invention the said rings (10) are formed
with a rounded surface disposed with said tapers (11, 11A).
In another embodiment of the present invention the said ring is a substantially
circular nylon ring.
30
In another embodiment of the present invention the said first inner section of
the centre ring (2) and first outer section of the lock ring (3) have substantially
identical diameters.
• 8
5 In another embodiment of the present invention the said rings (10) are disposed
in the first inner section of the said centre ring (2) and first outer section of the
lock ring (3).
Still another embodiment of the present invention the said tapers (11, 11A) are
carried out over the entire periphery of the chain ring, centre ring and lock ring.
10
In another preferred embodiment of the present invention is disclosed a
freewheel for a bicycle comprising a chain ring (1), an innerfreewheel centre ring
(2), an outer freewheel lock ring (3), a pair of rings (10), tapers (11, 11A), a pair of
pawls (4), and springs (5).
15
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described more fully hereinafter with
reference to the accompanying drawings in which the preferred embodiment of
the invention is shown. This invention may, however, be embodied in many
20 different forms and should not be construed as being limited to the embodiment
set forth herein. Rather, the embodiment is provided so that this disclosure will
be thorough, and will fully convey the scope of the invention to those skilled in
the art.
As shown in FIG.l, a conventional freewheel basically includes an outer ring 3, a
25 center ring 2 coaxially mounted on chain ring 1, a ball bearing assembly 6 having
104 steel balls (52 on each sides) rotatable coupling chain ring 1 to outer ring 3.
Chain Ring 1 is also referred to as a sprocket. It has teeth on its circumference
which engage a drive chain from freewheel to the front sprocket coupled with
the paddles. In a conventional freewheel, the Centre Ring 2, Chain Ring 1 and
30 Outer Ring 3 have Ball Races 7 pressed into them in order to accommodate a set
of 52 hardened Steel Balls 6 on each side. Thus, a conventional Freewheel usually
consists of 104 hardened Steel Balls 6 (52 on each side). Since, the Steel Balls 6
• 9
5 used are hardened, so all the corresponding components i.e. Chain Ring 1, Centre
Ring 2 as well as the Outer Ring 3 have to be hardened thus increasing the
manufacturing costs and leading to environmental pollution.
As shown in FIG.2, a new freewheel of the present invention includes an outer
10 ring 3, a center ring 2 coaxially mounted on chain ring 1 having tapers 11, 11, 11A
on center ring 2, outer ring 3 and chain ring 1 respectively for positioning of a
pair of nylon rings 10 replacing the ball bearing assembly 6 of the conventional
freewheel. Centre Ring 2 houses the Pawls 4, Springs 5 and Nylon Rings 10. Pawls
4 provide locking of the chain ring 1 when moved in the forward direction. As the
15 pawls 4 are always stretched out by the springs 5, these lock the Chain Ring 1
with the Centre Ring 2 by engaging against broached teeth inside the chain ring
1.
As shown in FIGS. 3 & 4, Ball Races 7 in a conventional freewheel which have
20 been eliminated in the new design of the present invention are illustrated. The
ball races 7 of FIG.1 have been eliminated and replaced with a simple taper 11 &
11A, thus easing the manufacturing process. Since the new design does not uses
hardened steel balls 6, only the chain ring 1 need to be hardened thus decreasing
the manufacturing cost as well as environmental pollution.
25
FIGS. 5 & 6 show the diagrammatic differences between a conventional
freewheel with ball races 7 for hardened steel balls 6 and the new design of the
present invention with a simple taper 11 & 11A housing the nylon rings 10.
30 FIGS. 7 & 8 depict the comparative illustration of cross-sectional views of a
conventional freewheel with a set of 104 hardened steel balls 6 and a new
freewheel design of the present invention with taper 11 & 11A housing a pair of
nylon rings 10.
• 10
5 FIGS. 9 & 10 depict the comparative illustration of a conventional Centre Ring 2
with Ball Races 7 and a new Centre Ring Design 2 of the present invention
without the Ball Races 7 and with a simple Taper 11.
FIGS. 11 & 12 show the comparative illustrations of a conventional chain ring 1
10 and a new chain ring 1 of the present invention without the Ball Races 7 and with
a simple Taper 11.
FIGS. 13 & 14 describe the comparative illustrations of a conventional outer ring
3 and a new outer ring 3 of the present invention with Taper 11.
15
As shown in FIG. 14, an illustration of pawl 4 of the present invention is depicted.
As shown in FIG. 15, an illustration of spring 5 of the present invention is shows.
20 As shown in FIG.16, an illustration of a conventional steel ball 6 is indicated.
As shown in FIG.17, an illustration of a nylon ring 10 of the present invention is
shown.
25 While several preferred embodiments have been chosen to illustrate the present
invention, it will be apparent to those skilled in the art from this disclosure that
various changes and modifications can be made herein without departing from
the scope of the invention as defined in the appended claims. Furthermore, the
foregoing description of the embodiments according to the present invention is
30 provided for illustration only, and not for the purpose of limiting the invention as
defined by the appended claims and their equivalents.

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11
CLAIMS
We Claim:
1. A freewheel assembly for attachment between a wheel and a
transmission device of a bicycle comprising:
an inner freewheel centre ring (2) having a first inner section with a first
diameter and a second inner section with a second diameter that is
smaller than the said first diameter, the first section having a ring (10), a
taper (11) formed at one side of the said centre ring (2), and a pair of
pawls (4) provide locking of the chain ring 1 through the springs (5);
a chain ring (1) mounted over the centre ring (2) of the freewheel having
taper (l1A) formed at inner periphery of the said chain ring (1); and
an outer freewheel lock ring (3) having a first outer section with a third
diameter and a second outer section with a fourth diameter that is
smaller than the said third diameter, the first outer section having a ring
(10), and a taper (11) formed at one side of the centre ring (2) for the
engagement with chain ring (1);
wherein:
the said outer freewheel lock ring (3), and centre ring (2) are coaxially
mounted on the said chain ring (1) having tapers (11, 11, 11A) on centre
ring (2), lock ring (3) and chain ring (1) respectively for positioning of a
pair of the said rings 10.
2. The freewheel assembly as claimed in claim 1, wherein the said rings (10)
are made from polyamide, nylon, or similar material known in the state of
the art.
3. The freewheel assembly as claimed in claim 1, wherein the said rings (10)
are formed with a rounded surface disposed with said tapers (11, 11A).
4. The freewheel assembly as claimed in claim 1, wherein the said ring is a
40 substantially circular nylon ring.
ORIGINAL
• 12
5 5. The freewheel assembly as claimed in claim 1, wherein the said first inner
section of the centre ring (2) and first outer section of the lock ring (3)
have substantially identical diameters.
6. The freewheel assembly as claimed in claim 5, wherein the said rings (10)
10 are disposed in the first inner section of the said centre ring (2) and first
outer section of the lock ring (3).
7. The freewheel assembly as claimed in claim 1, wherein the said tapers
(11, 11A) are carried out over the entire periphery of the chain ring,
15 centre ring and lock ring.
8. A freewheel for a bicycle comprising a chain ring (1), an inner freewheel
centre ring (2), an outer freewheel lock ring (3), a pair of rings (10), tapers
(11, 11A), a pair of pawls (4), and springs (5).
20
9. A freewheel and an assembly for attachment between a wheel and a
transmission device of a bicycle as described substantially herein with
reference to the accompanying description and drawings.