Note: Descriptions are shown in the official language in which they were submitted.
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TRANSMISSION APPARATUS FOR A BICYCLE
BACKGROUND OF THE INVENTION
1. Field of the Invention
[002] This invention relates to a transmission apparatus having an endless
transmission
linking loop applied over first and second rotating members, so as to transmit
a rotation
between the first rotating member and the second rotating member. More
particularly, the
present invention relates to a transmission apparatus used in a bicycle,
having an endless
transmission linking loop applied over first and second rotating shafts so as
to transmit a
rotation from the first rotating shaft to the second rotating shaft, as used
in a bicycle.
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2. Description of the Background Art
[003] Many different types of transmission assemblies are known, and are
commercially
available. One example of a known transmission apparatus, for use on a
bicycle, is disclosed
in Japanese Utility Model Application No. Sho 59 (1984)-172882 , as well as
Japanese Utility
Model Laid-Open No. Sho 61 (1986) - 87190, for example.
[004] The transmission apparatus disclosed in Japanese Utility Model
Application No.
Sho 59 (1984)-172882 is comprised of a single-stage or multi-stage front chain
gear device
drivingly connected to a main drive shaft; a mufti-stage sprocket device
drivingly connected
to the rear hub and having more stages than that of the front chain gear
device; and a chain
applied over the front chain gear device and the mufti-stage sprocket device.
Then, in the case
of performing a transmission gear change, the chain is transferred from one
sprocket of the
mufti-stage sprocket device to other sprocket by the rear derailleur, operated
by an operating
[005] In the case of the transmissions taught by these references, there
occurs a possibility
that the chain is removed sometimes from either the chain gear or the
sprocket, while the
chain is inclined in respect to a plane crossing at a right angle with an
axial direction when the
chain is applied over the chain gear and the sprocket placed in an axial
different direction
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because the chain gear of the front chain gear device cannot be moved axially
and the
multi-stage sprocket device constituted by a plurality of sprockets axially
arranged shows a
large axial width size. Then, when there remains a small clearance between the
front chain
gear device and the mufti-stage sprocket device, the chain is removed more
easily because
inclination of the chain in respect to the right angle crossing plane becomes
larger.
[006] The present invention has been invented in view of the circumstances as
described
above, and it is an object of the present invention to provide a transmission
apparatus capable
of preventing the endless transmission linking loop from being removed from
the rotating
member even in the case that there remains a small inter-axis distance between
the two
rotating shafts to which each of the two rotating members having the endless
transmission
linking loop wound around themselves is drivingly connected.
[007] It is another object of the present invention to minimize or reduce the
size of the
transmission apparatus.
[008] Although the known devices have some utility for their intended
purposes, there is
still a need to provide an improved transmission which eliminates the
traditional chain drive
system for use with a bicycle. More particularly, there is a need for an
improved bicycle
transmission including components designed to solve the above-mentioned
problems.
3
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SUMMARY OF THE INVENTION
[009] The invention according to a first aspect hereof is a transmission
apparatus including
a first rotating member drivingly connected to a first rotating shaft, and
including one or more
first rotating elements. The transmission also includes a second rotating
member drivingly
connected to a second rotating shaft, arranged in parallel with the first
rotating shaft. The
second rotating shaft is arranged in the rotary center line direction of the
second rotating shaft
and has a greater number of second rotating elements than the number of first
rotating
elements.
[010] The transmission also includes an endless transmission linking loop,
interconnecting
the first rotating member and the second rotating member to transmit a
rotation between the
first rotating shaft and the second rotating shaft. The linking loop may be a
belt or chain. The
transmission further includes a transmission gear shift mechanism for
positioning the endless
transmission linking loop on a selected one of the second rotating elements
for a transmission
operation.
[011] In the transmission according to a first embodiment hereof, the first
rotating member
is movably supported on the first rotating shaft with its rotary center line
direction oriented
such a way that the endless transmission linking loop is applied over the
first rotating member
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and the second rotating member in parallel with a plane crossing the rotary
center line of the
first rotating shaft at a right angle.
[012J In accordance with the present invention, the endless transmission
linking loop is
substantially prevented from being inclined with respect to the right-angle
crossing plane,
because the first rotating member is moved in a rotary center line direction
in such a way that
the endless transmission linking loop is applied over the first rotating
member and the second
rotating member along the right angle crossing plane in respect to the rotary
center line also in
the case that the endless transmission linking loop is wound around any one of
the more
predetermined number of second rotating member elements than that of the first
rotating
member elements.
[013] As a result, in accordance with a first aspect of the invention, the
following effects
can be attained. That is, the endless transmission linking loop is retained in
place on the first
and second rotating member elements without any relation with an inter-axis
distance
between the first rotating shaft and the second rotating shaft and accordingly
also in the case
of short inter-axis distance, because the endless transmission linking loop is
prevented from
being inclined in respect to the plane crossing at a right angle with the
rotary center line.
[014] The invention described in a second aspect is constructed such that the
first rotating
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member in the transmission apparatus described in the first aspect is
constituted by the first
one rotating member element, the slide mechanism allowing the first rotating
member to
move in its rotary center line direction is arranged between the first
rotating shaft and the first
rotating member, and the first rotating member is drivingly connected to the
first rotating
shaft through the slide mechanism.
[O15J In accordance with the aforesaid circumstances, the moving range of the
first rotating
member in the rotary center line direction is minimized, because the width of
the first rotating
member in the rotary center line direction is minimized.
[016J As a result, in accordance with the present invention described in the
second aspect,
the following effects can be attained in addition to the effect of the
invention described in the
first aspect. That is, a size of the of the transmission apparatus in the
rotary center line
direction is made small, because the moving range of the first rotating member
in the rotary
center line direction is minimized.
[017J For a more complete understanding of the present invention, the reader
is referred to
the following detailed description section, which should be read in
conjunction with the
accompanying drawings. Throughout the following detailed description and in
the drawings,
like numbers refer to like parts.
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BRIEF DESCRIPTION OF THE DRAWINGS
[018] Figure 1 is a schematic left elevational view of a bicycle incorporating
a transmission
according to a selected illustrative embodiment of the present invention.
[019J Figure 2 is a sectional view of the transmission apparatus installed on
the bicycle of
Fig. 1, taken along the line II-II in Fig. 3.
[020J Figure 3 is a sectional view of the transmission apparatus of Figure 2,
taken along the
line III-III of Fig. 2, with a second case part of the transmission apparatus
deleted from the
drawing for illustrative purposes.
[021] Figure 4 is a sectional detail view of part of the transmission of
Figures 2-3, taken
along the line IV IV of Fig. 2.
[022] Figure 5 is a sectional detail view of part of the transmission of
Figures 2-3, taken
along the line V V of Fig. 3.
[023] Figure 6 is a sectional detail view of part of the transmission of
Figures 2-3, showing
the derailleur and the tensioner, and taken along the line VI-VI of Fig. 3.
[024] Figure 7 is a detail view of part of the transmission of Figures 2-3,
seen from an
arrow VII of Fig. 5; and
[025] Figure 8 is a sectional detail view of part of the transmission of
Figures 2-3, taken
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along the line VIII-VIII of Fig. 2.
DETAILED DESCRIPTION
[026] Referring now to Figs. 1 to 8, a selected illustrative embodiment of the
present
invention will be described. It should be understood that the following
description is
intended to illustrate, rather thm to limit the invention.
[027] Referring to Figure 1 a bicycle B is shown, in which a transmission
apparatus T
according to the present invention is used. The bicycle B is a bicycle of the
type commonly
referred to as a'mountain bike', and may be used off road and for down-hill
riding. The
bicycle B may be ridden in a timed competition, descending a non-paved course
including a
high-speed corner, a jump section in a forest road, and/or other similar
features.
[028] A body frame F of the bicycle B includes a head pipe 1 for pivotally
supporting a
front fork 5 in a steering manner, to guide movement of a front wheel WF at
its lower end. The
front fork 5 includes a pair of right and left fork sections joined at the
top.
[029] The body frame F also includes a pair offright and left main frame
sections 2
extending downwardly and rearwardly from the head pipe 1, as well as a down
tube 3
extending downwardly from front ends of both main frame sections 2 at lower
portions in a
rearward and downwardly slanting direction. The body frame F also includes a
saddle frame 4
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extending rearwardly from the central part of each of the main frame sections
2, to support a
seat or saddle 6 thereon.
[030] As used herein, technical expressions of "upper and lower", "forward and
rearward",
and "right and left" in this specification are expressed in reference to a
bicycle and coincide
with "upper and lower", "forward and rearward", and "right and left" of the
bicycle,
respectively, considered from a vantage point of a rider thereof, sitting on
the seat 6 and
facing forwardly. In addition, a figure as seen from a side view means a
figure seen from the
right or left direction.
(031 ] A pair of right and left swing arms 8 include front ends 8a, which are
pivotally
connected to the main frame sections 2 by a pivot arm 7. The swing arms 8
pivotally support
the rear wheel WR through a wheel shaft 9, fixed to the rear end of each swing
arm. The swing
arms are supported in an oscillating manner at the pivot shaft 7, acting as a
pivot portion
arranged at the rear parts 2a of both main frame sections 2. Both swing arms 8
are also
connected to both main frame sections 2 through a suspension 10 having both a
compression
spring l0a and a damper l Ob. The swing arms 8 can be oscillated in an upward
and downward
direction around the pivot shaft 7, together with the rear wheel WR.
9
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[032] The main drive shaft 11 and the transmission apparatus, including the
transmission
apparatus T and a driving power trmsfer mechanism are installed as component
parts of the
bicycle B. Then, as shown in Fig. 1, a transmission apparatus T is installed
between the rear
parts 2a of both main frame sections 2 and the rear part 3a of the down tube
3, positioned in
front of the rear parts 2a of the lower portion of the body frame F.
[033] The transmission apparatus T is fixed to the major shaft l la of the
main drive shaft
11 and to the aforementioned rear frame parts 2a, 3a. A driving force transfer
mechanism is
arranged at aright side of a body central line Ll (refer to Fig. 2), as seen
from an upper and
lower direction in a top plan view, a bicycle body width direction (coinciding
with the right
and left direction) and the transmission apparatus T.
[034] Referring to Fig. 3 in addition to Fig. 1, the transmission apparatus T
has a metallic
case 20, including a pair of right and left first and second case parts 21,
22, connected by bolts
B 1 at many bolt fastening segments 21 a, 22a (Figure 2) formed at the
peripheral edge, and a
cap 25 to be described later. The case 20 is fixed to the main frame 2 and the
down tube 3 by
bolts B2 at a pair of fixing segments 20a, formed at the peripheral edge part
of the
transmission case 20.
[035] The main drive shaft 11 acting as a pedal-operated main drive shaft has
a major shaft
to
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11 a arranged to pass through the lower part of the case 20 in a right-to-left
direction, and a
pair of pedal arms l lb connected to each of the right and left ends of the
major shaft 11 a
projected outside the case 20. Then, the pedal 12 (refer to Fig. 1) is
rotatably arranged at each
of the pedal arms l lb.
[036] An output shaft 24, a derailleur shaft 61 of the transmission apparatus
T and the pivot
shaft 7 are arranged above the major shaft 11 a of the main drive shaft 11,
and extending
outside of the case 20, to extend in a right and left direction in such a way
that their rotary
center line L4 and central axis lines LS, L2 may become in parallel to each
other, and each of
the lines L4, LS and L2 may become in parallel with the rotary center line L3
of the main
drive shaft 11. Then, the main drive shaft 11, output shaft 24, derailleur
shaft 61 and pivot
shaft 7 occupy overlapped positions in the right and left direction, and at
the same time, they
are crossed with the body central line Ll as seen in a top plan view.
[037] The pivot shaft 7 passes through and extends inside a pair of
cylindrical bushings 13
held at each of the pass-through holes 2c formed at the pivot hub 2b of the
rear part 2a of each
of the main frame sections 2 and the pass-through holes 23 formed at the
cylindrical parts 21b,
22b of the first and second case parts 21, 22. The pivot shaft 7 is also fixed
to the rear part
2a of each of the main frame sections 2, as noted.
11
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[038J Each of the swing arms 8 is supported at the pivot shaft 7 in an
oscillatable manner
by an arrangement in which the front end 8a positioned at the right and left
sides of the case
20 and between the case 20 and the rear part 2a of each of the main frame
sections 2 in a right
and left direction is supported at the pivot shaft 7 projected outside the
case 20 through a
collar 18 and a bearing 14.
[039] Referring to Fig. 1, the output shaft 24 and the pivot shaft 7 are
located within a
rotating locus of the pedal arm l lb. Then, the output shaft 24 and the pivot
shaft 7 are
arranged in respect to the body frame F in such a way that the rotary center
line L4 of the
output shaft 24 is positioned in an imaginary oscillation range in an
imaginary plane H
including an oscillation central line L2 for both swing arms 8 (coinciding
with the central axis
line L2 of the pivot shaft 7) and the rotary center line L6 of the rear wheel
WR (coinciding
with the central axis line of the wheel shaft 9).
[040] That is, although the imaginary plane H oscillates around the
oscillation central line
L2 within the aforesaid imaginary oscillation range in correspondence with the
oscillation
range of both swing arms 8, the rotary center line L4 of the output shaft 24
is positioned in the
imaginary oscillation range.
[041] Referring to Figs. 2 and 3, the output shaft 24 stored in the case 20
has a right end
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24a acting as one end projected outwardly from the second case 22, and then a
main drive
sprocket 15 acting as an output driving rotating member is connected to the
right end 24a.
Referring to Fig. 1 together with these figures, a chain 16, acting as a
flexible endless
transmission output linking loop, is applied between the main drive sprocket
15 and the
driven sprocket 17, acting as the output driven rotating member drivingly
connected to the
rear wheel WR. It will be understood that with appropriate modifications, a
belt could be
used in place of the chain as a linking loop.
[042] In this case, the main drive sprocket 15, chain 16 and driven sprocket
17 constitute
the aforesaid driving power transfer mechanism, for use in driving the rear
wheel WR acting
as the driving wheel. Then, the output shaft 24 always cooperates with the
rear wheel WR and
is rotated in a normal rotating direction AO (a rotating direction where the
bicycle B is moved
in a forward direction, wherein a normal rotating direction of various kinds
of shaft and
sprocket when the main drive shaft 11 rotates in a normal rotating direction
AO is hereinafter
denoted by symbol AO), and sometimes in an inverse rotating direction opposite
to the normal
rotating direction A0.
[043] Further, the present invention will be described mainly in reference to
the main drive
shaft 11 and the transmission apparatus T.
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[044] Refers ing now to Figs. 2 and 3, the transmission apparatus T includes
the case 20,
along with a transmission mechanism M1 and a gear shift mechanism M2, both of
which are
stored in the case 20. The main drive shaft 11 is stored at its portion
extending through the
case 20 and held by the case 20. The gear shift mechanism M2, installed at the
case 20 to
shift the transmission mechanism M1 to a desired transmission position, is
operatively
connected to the transmission mechanism M 1.
[045] In addition, the transmission mechanism Ml is provided with a one-way
clutch 32,
slide mechanism S, main drive sprocket 30, driven sprocket member 40, chain 48
and output
shaft 24, to be described later.
[046] The main drive shaft 11, acting as a first rotating shaft, is rotatably
supported at the
case 20 through a pair of right and left bearings 25. Each of the bearings 25,
arranged at
portions near both ends of the major shaft l la, is held at one of the
respective case parts 21,
22 within the case 20. A main sprocket member 30, acting as the first rotating
member or the
driving rotating member, is coaxially supported on the major shaft l la,
between both bearings
25. The main sprocket member 30 includes a main drive sprocket 31.
[047] The main drive sprocket 31 is drivingly connected to the major shaft 11
a through a
one-way clutch 32, arranged coaxial with the major shaft l la and through the
slide
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mechanism S, and then the main drive sprocket 31 is rotationally driven by the
main drive
shaft 11. Then, as shown in Fig. 2, the main drive sprocket 31 and the one-way
clutch 32 are
arranged at positions where they are not overlapped to each other in a
direction A3 of the
rotary center line L3 of the main drive shaft 11.
[048] Referring to Fig. 4 together with these figures, the one-way clutch 32
is provided
with a pair of ratchet pawls 32c acting as clutch elements, a clutch inner
drive section 32a
constituted by a part of the major shaft 11 a, a clutch intermediate collar
32b constituted by a
part of an inner cylinder 34 to be described later, and a ring spring 32d held
by the clutch
inner drive section 32a.
[049] Each of the ratchet pawls 32c, supported at its base part 32c1 in a
supporting part
32d1 composed of a notch formed at the outer circumferential surface of the
clutch inner drive
section 32a in an oscillatable manner, is biased by the ring spring 32d in
such a way that its
extremity end 32c2 may be engaged with many teeth 32b1 formed at the inner
circumferential
surface of the clutch intermediate collar 32b.
[050] Then, when the clutch inner drive section 32a is rotated relatively in
respect to the
clutch intermediate collar 32b in the normal rotating direction AO of the main
drive shaft 11,
the extremity end 32c2 of each of the clutch pawls 32c is engaged with the
claw 32b1, thereby
is
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the clutch inner drive section 32a and the clutch intermediate collar 32b are
concurrently
rotated.
[O51 ] Conversely, when the clutch inner drive section 32a is relatively
rotated in an inverse
rotating direction opposite to the normal rotating direction A0, the extremity
end 32c2 of each
of the clutch pawls 32c is not engaged with the tooth 32b1, and as a result,
the clutch inner
drive section 32a and the clutch intermediate collar 32b can be rotated
independently past
each other. Due to this fact, one-way clutch 32 transmits only the rotation in
the normal
rotating direction AO of the main drive shaft 11 to the main drive sprocket
31, and permits
slippage when the main drive shaft 11 is rotated in the opposite direction.
[052] Referring to Figs. 2 and 3, a slide mechanism S is provided between the
one-way
clutch 32 and the main drive sprocket 31, enabling the main drive sprocket 31
to be moved
axially on the shaft 11 toward the rotary center line direction A3 in respect
to the major shaft
11 a, and integrally rotated with the clutch intermediate collar 32b of the
one-way clutch 32 at
the same time.
[053] The slide mechanism S is provided with an inner cylinder 34, having its
part
constituting the clutch intermediate collar 32b, and rotatably supported at
the major shaft l la
in a coaxial relation with it through a pair of bearings 33 at an outer
circumference of the
16
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major shaft lla.
[054] The slide mechanism S also includes an outer cylinder 35, arranged
coaxially outside
the inner cylinder 34, and a ball spline mechanism 36 acting as an engaging
mechanism
arranged between the outer circumferential surface of the inner cylinder 34
and the inner
circumferential surface of the outer cylinder 35. Then, the main drive
sprocket 31 and the
chain guide 37 are connected to the outer cylinder 35 and integrally fastened
by bolts B3; the
main drive sprocket 31, chain guide 37 and outer cylinder 35 are rotated in an
integral manner,
and moved integrally in a rotary center line direction axially along the major
shaft 11 a.
[055] The ball spline mechanism 36 is provided for integrally rotating the
inner cylinder 34,
main drive sprocket 31 and outer cylinder 35, i.e. integrally rotating the
slide mechanism S
and the main drive sprocket 31 and enabling the main drive sprocket 31 and the
outer cylinder
35 to be moved in the rotary center line direction A3 against the inner
cylinder 34 and the
major shaft lla.
[056] The ball spline mechanism 36 includes a pair of storing grooves 36a, 36b
of
semi-circular section, which are formed to face towards each other in a
diameter direction at
equal angular positions ~n a circumferential direction at the outer
circumferential surface of
the inner cylinder 34 and the inner circumferential surface of the outer
cylinder 35; and a row
17
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of balls composed of a plurality of balls 36c acting as engagement elements
rotatably stored in
the pair of storing grooves 36a, 36b and engaged with the inner cylinder 34
and the outer
cylinder 35 in a circumferential direction.
[057] As the pair of storing grooves 36a, 36b, a plurality of sets, five sets
in this preferred
embodiment are arranged, a width of each of the storing grooves 36a, 36b in
the rotary center
line direction A3 is larger than a width of the aforesaid row of balls at the
rotary center line
direction A3, and the main drive sprocket 31 can be translated in the rotary
center line
direction A3 .within a moving range equal to the translation moving range of
the
changing-over moving range of the guide pulley 63 of the derailleur 60, to be
described later.
[058] Then, the inner cylinder 34 and the outer cylinder 35 are provided with
first stoppers
34a, 35a and second stoppers 34b, 35b for restricting motion of the aforesaid
row of balls in
the rotary center line direction A3 so as to define the aforesaid moving range
of the main drive
sprocket 31 and the outer cylinder 35 and to prevent the balls 36c from being
dropped.
[059] The output shaft 24 acting as the second rotating shaft is rotatably
supported at the
case 20 through a pair of bearings 38 each of which is held at both case parts
21, 22 within the
case 20. Due to this fact, the case 20 is a member fixed to and arranged at
the body frame F so
as to support the main drive shaft 11 and the output shaft 24 in a rotatable
manner and support
18
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other composing members in the transmission mechanism M1 through these shafts
11 and 24
and further, support the gear shift mechanism M2.
[060] A mufti-stage driven rotating member for transmission acting as a
secondary rotating
member constituted by a predetermined plurality of more than the number of the
main drive
sprockets 31 is drivingly connected to the output shaft 24. The mufti-stage
driven rotating
member provides the rotating members of the main drive sprocket 30 at the
position crossing
with the body central line L1, as seen in a top plan view, in such a way that
the driven rotating
member is always rotated in integral with the output shaft 24 between both
bearings 38.
[061] The aforesaid mufti-stage driven rotating member in this preferred
embodiment is a
mufti-stage driven sprocket member 40 constituted by transmission sprockets 41
to 47 acting
as the second rotating elements for seven different kinds of transmission
having the aforesaid
predetermined number of 7 and different outer diameters (i.e. tip diameters).
[062] Then, seven transmission sprockets 41 to 47 ranging from the fastest
speed 7-speed
transmission sprocket 47 having the minimum outer diameter to the slowest
speed one-speed
transmission sprocket 41 having the maximum outer diameter are arranged side
by side in a
direction 44 of the rotary center line L4 also acting as the rotary center
line of the driven
sprocket member 40, spline connected at the outer circumferential surface in
coaxial with the
19
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output shaft 24 and drivingly connected to the output shaft 24.
[063] A transmission chain 48, acting as a flexible endless transmission
linking loop is
applied over the main sprocket member 30 and the driven sprocket member 40,
and then a
rotation is transmitted by the chain 48 between the main drive shaft 11 and
the output shaft 24.
More practically, the gear shift mechanism M2 is set such that a chain 48 is
applied between
the main drive sprocket 31 and an operating sprocket acting as a certain
transmission sprocket,
selected as one element from the transmission sprockets 41 to 47 by the gear
shift mechanism
M2 and having the chain 48 wound around it (the transmission sprocket 47 in
Fig. 2) by
replacing the chain 48 among the transmission sprockets 41 to 47.
[064] As a result of the above-described configuration of parts, the output
shaft 24 is
rotationally driven by the main drive shaft 11 under a transmission ratio
determined by the
aforesaid operating sprocket drivingly connected to the main drive sprocket 31
through the
chain 48. Then, the power of the output shaft 24 is transmitted to the rear
wheel WR through
the main drive sprocket 15, chain 16 and driven sprocket 17 (refer to Fig. 1).
[065] Referring to Figs. 3, 5 and 6, the gear shift mechanism M2 operated by
the
transmission operating mechanism 50 is comprised of a derailleur 60 having a
guide pulley 63,
and a tension applying unit 70 having a tension pulley 72. Then, the chain 48
is wound around
2o
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the main drive sprocket 31 and the aforesaid sprocket, and the guide pulley 63
and the tension
pulley 72 arranged at a loosening side of the chain 48.
[066] Referring to Fig. 1 together with these figures, the transmission
operating mechanism
50 is comprised of a transmission operating member 51 constituted by a
transmission lever or
the like operated by a driver, a wire 52 for operatively connecting the
transmission operating
member S 1 with the derailleur 60 to transmit an operation of the transmission
operating
member 51 to the derailleur 60, and an outer tube 53 covering the wire 52.
Then, the portion
near the case 20 of the wire 52 extending longer than the outer tube 53 is
covered by a
bellows 57 for prohibiting water and dust.
[067] Referring to Figs. 2, 3 and 5 to 7, the derailleur 60 is comprised of a
derailleur shaft
61 rotatably supported at the case 20; a derailleur arm 62 having base ends
62a1, 62b1
slidably fitted to and supported at the derailleur shaft 61 in such a way that
they can be
rotationally moved and translated in a direction of the central axis line; a
guide pulley 63
acting as a guide rotating member rotatably supported at the extremity ends
62a2, 62b2 of the
derailleur arm 62; a pin 65 acting as an operating member for moving the
derailleur arm 62 in
respect to the derailleur shaft 61 in response to a transmission operation by
the transmission
operating mechanism 50; a balance spring 66 for acting a balance torque Tb
balancing with a
21
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torque Ta acting from the derailleur 62 to the derailleur shaft 61 against the
derailleur shaft
61; and a return spring 64 for returning the derailleur ann 62 to the first
position to be
described later.
[068] The derailleur shaft 61 is supported at the case 20 in such a way that
its central axis
line 5 is in parallel with the rotary center line 17 of the guide pulley 63
and the rotary center
line L4 of the driven sprocket member 40. More practically, one end 61 a of
the derailleur
shaft 61 is fitted to a holding hole 25c of a cylinder 25a of the cap 25
connected to the fist
case 21 by bolts B4 and supported at the first case 21 through the cap 25, and
the other end
61b is fitted to a holding hole 22c of a second case 22 and supported at the
second case 22.
[069] Motion of the derailleur shaft 61 in one direction (a leftward direction
in Figs. 2 and
5) at the central axis line direction AS is restricted by an operation in
which the washer 67
fitted to the step part formed at an outer circumferential surface of the
derailleur shaft 61 is
' abutted against the extremity end of the cylinder 25a having the holding
hole 25c formed at
the cap 25.
[070] Motion of the derailleur shaft 61 in the other direction (a rightward
direction in Figs.
2 and 5) at the central axis line direction AS is restricted under a state of
allowing a rotation of
the derailleur shaft 61 by an operation in which a set ring 69 fitted to an
annular groove
22
CA 02467512 2004-05-18
formed at the outer circumferential surface is abutted against the washer 68
fitted to the outer
circumferential surface of a portion projected from the cap 25 at one end 61a,
respectively.
[071] The other end 66b of the balance spring 66 comprised of a twisted coil
spring having
one end 66a engaged with the cap 25 is engaged with one end 61 a having a
guide pipe 56 for
use in guiding the wire 52 fixed to it and having an inserting hole 61 c into
which the wire 52
is inserted.
[072] Then, the balancing torque Tb based on a spring force generated at the
balancing
spring 66 under a rotation of the derailleur shaft 61 along with a rotation of
the derailleur arm
62 may act on the derailleur shaft 61, thereby a position of the derailleur
shaft 61 in its
rotating direction is defined and then the derailleur arm 62 and the guide
pulley 63 are rotated
on the derailleur shaft 61 rotatably supported at the case 20 in such a way
that the chain 48
can be replaced among the transmission sprockets 41 to 47 having different
outer diameters in
response to the transmission operation at the transmission operating mechanism
Ni2.
[073] The derailleur shaft 61 is formed with a storing hole 61d for movably
storing a
column-like operating element 54 connected to the wire 52 by the set screw 55
fastening the
wire 52 in a direction A5 of the central axis line L5; and a guide hole 61 a
acting as a guide
part for use in guiding the pin 65 moved by the aforesaid operating element 54
through
23
CA 02467512 2004-05-18
engagement with the operating element 54.
[074] The storing hole 61d is a column-like hole with the central axis line L5
of the
derailleur shaft 61 being applied as a central axis line. The guide hole 61 a
is released to the
storing hole 61d and is constituted by a pair of longitudinal holes positioned
in opposition to
the derailleur shaft 61 in its diameter direction. Each of the aforesaid
longitudinal holes
extends in the central axis line direction A5 and at the same time formed in a
helical shape
displaced in a circumferential direction.
[075J The pin 65 is inserted into the guide hole 61e, engaged with the
derailleur shaft 61
(refer to Figs. 2 and 6) to cause the derailleur arm 62 and the guide pulley
63 to be rotated in
respect to the derailleur shaft 61 within a changing-over moving range
described later while
being guided by the guide hole 61 a and moved in response to a transmission
operation
performed by the transmission operating mechanism M2 and at the same time to
be translated
toward the central axis line direction A5 of the derailleur shaft 61.
[076) The derailleur arm 62 has a cylindrical hub 62c slidably fitted to an
outer
circumference of the derailleur shaft 61 to be translated in a central axis
line direction A5 and
rotated; a pair of first and second arms 62a, 62b in which the base ends 62a1,
62b1 are press
fitted to the outer circumference of the hub 62c and fixed there; a rivet 62e
acting as a
24
CA 02467512 2004-05-18
connecting member inserted into a collar 62d arranged at the extremity ends of
both arms 62a,
62b to define a clearance between both arms 62a, 62b so as to connect both
arms 62a, 62b;
and a supporting shaft 62f rotatably supported at the outer circumference of
the collar 62d
fitted to the outer circumference of the rivet 62e and for rotatably
supporting the guide pulley
63 between the first arid second arms 62a, 62b.
[077] Then, the guide pulley 63 having the chain 48 wound around it is rotated
around the
supporting shaft 62f with the central line in parallel with the rotary center
line L4 of a driven
sprocket 40 and the output shaft 24 being applied as a rotary center line L7.
[078] Also referring to Fig. 8, the derailleur arm 62 is driven by the pin 65
moved in
response to the transmission operation based on the operation of the
transmission operating
member 51 (refer to Fig. 1), and the pin 65 inserted into the guide hole 61e
to translate in the
central axis line direction AS and rotate in a circumferential direction of
the derailleur shaft 61
is fixed to the derailleur arm 62. Due to this fact, both ends of the pin 65
extending to pass
through the guide hole 61e and a pair of through-holes 62c1 of the hub 62c are
press fitted
into a pair of pass-through holes 62b 1 formed at the base end 62b 1 of the
second arm 62b and
fixed there.
[079] In addition, the extremity end of the second arm 62b is formed with a
spring storing
CA 02467512 2004-05-18
part 62b2 storing a tension spring 73 of a tensioner 70 to be described later,
and the tension
spring 73 is arranged in the spring storing part 62b2 so as to enclose the
rivet 62e.
[080] Referring to Fig. S, a return spring 64 composed of the compression coil
spring is
arranged in the case 20 in such a way that its one end is abutted against a
spring receiver of
the cap 25, and the other end is abutted against the base end 62a1 of the
first arm 62a. Then,
the return spring 64 biases the derailleur arm 62 in such a way that the base
end 62b 1 of the
second arm 62b is abutted against a stopper 22d formed at the second case 22
and formed
with a holding hole 22c when the derailleur arm 62 occupies the first position
of the
maximum high speed transmission position where the chain 48 is wound around
the
transmission sprocket 47. At this time, the pin 65 is positioned at one end of
the guide hole
61e and a slight clearance is formed between it and one edge 61f of the hole.
[081 ] Referring to Figs. 3 and 4, the tensioner 70 is comprised of a holder
71 rotatably
supported at the collar 62d of the derailleur arm 62 between the first and
second arms 62a,
62b; a tension pulley 72 acting as a tension rotating member rotatably
supported at the holder
71; and a tension spring 73. The holder 71 is comprised of a pair of first and
second arms 71 a,
71b press fitted and fixed to the outer circumference of the supporting shaft
62f at its base
end; a collar 71c arranged at the extremity ends of both arms 71a, 71b to
define a clearance
26
CA 02467512 2004-05-18
between both arms 71 a, 71b and acting as a supporting shaft of the tension
pulley 72; a rivet
71 d inserted into the collar 71 c and acting as a connecting member holding
the collar 71 c to
connect both arms 71a, 71b; and a bearing 71e fitted to the outer
circumference of the collar
71 c.
[082] The tension pulley 72 is rotatably supported at the collar 71c between
the first and
second arms 71 a, 71b through a bearing 71 e. Then, the chain 48 is wound
around a guide
pulley 63 and a tension pulley 72 while the first and second arms 71a, 71b are
being applied _
as a chain guide.
[083] As shown in Fig. 3, the tension spring 73 comprised of a twisted coil
spring is
engaged with the second arm 62b at one end 73a and engaged with the second arm
71b of the
tensioner 70 at the other end 73b, its spring force biases the holder 71 and
subsequently the
tension pulley 72, applies a tension force of appropriate value to the chain
48 to prevent the
chain 48 from being loosened.
[084] Referring now to Figs. 2, 3 and 5, there will be described about a
changing-over
motion range of the guide pulley 63 and a moving path of the guide pulley 63
within the
changing-over motion range for enabling a replacing of the chain 48 guided by
the guide
pulley 63 to each of the transmission sprockets 41 to 47.
27
CA 02467512 2004-05-18
[085] The aforesaid changing-over motion range of the guide pulley 63 under a
transmission operation of the transmission operating mechanism 50 is defined
by the first
position where the derailleur arm 62 is abutted against the stopper 22d by a
spring force of the
return spring 64 and the second position where the pin 65 is moved in one
direction (a
leftward direction as seen in Figs. 2 and 5) and the derailleur arm 62 is
abutted against the
washer 67 acting as a stopper so as to cause the position at the central axis
line direction AS to
be set by a cylinder 25a of the cap 25.
[086] A translation motion range of the motion range in the central axis line
direction AS in
the aforesaid changing-over motion range is set in such a way that the guide
pulley 63 can
occupy the position at the same central axis line direction as that of the
transmission sprocket
47 of minimum outer diameter and the transmission sprocket 41 of maximum outer
diameter
of the transmission sprockets positioned at both ends of the driven sprocket
member 40 in the
central axis line direction A4, and in this case, it is determined in
reference to the position of
the stopper 22d at the aforesaid first position and the position of the washer
67 in the central
axis line direction AS at the aforesaid second position.
[087] In turn, a rotating motion range of the motion range in a rotating
direction in the
aforesaid changing-over motion range is set in correspondence with the
transmission sprocket
28
CA 02467512 2004-05-18
47 of the minimum outer diameter and the transmission sprocket 41 of the
maximum outer
diameter in such a way that the guide pulley 63 occupies the position spaced
apart outwardly
from these transmission sprockets 47, 41 by a predetermined distance in a
diameter direction.
[088) In this case, the derailleur shaft 61 is rotatable in respect to the
case 20, and in turn,
the derailleur shaft is supported under a state in which motion in the central
axis line direction
AS is substantially prohibited, so that the aforesaid rotating motion range is
produced in
reference to the shape of the guide hole 61e and a spring force of the tension
spring 73 acting
against the derailleur arm 62 and it is determined in reference to a balancing
position of the
derailleur shaft 61 in the rotating direction where a torque Ta and a
balancing torque Tb are
balanced at the aforesaid first position and the aforesaid second position in
dependence on the
torque Ta acting on the derailleur shaft 61 through the pin 65 and the
balancing torque Tb
acted on the derailleur shaft 61 generated by a spring force of the balancing
spring 66 so as to
be balanced with the torque Ta.
[089] Both orientations and values of these torques Ta, Tb are influenced by
some factors
such as a spring constant of the tension spring 73, a spring constant of the
balancing spring 66,
an acting position of a spring force of each of the springs 73, 66 and a shape
of each of the
derailleur shaft 61, derailleur arm 62 and guide hole 61e. Thus, there will be
described a case
29
CA 02467512 2004-05-18
as one example in which the aforesaid rotating motion range and the aforesaid
motion path are
set in reference to the spring forces of the tension spring 73 and the
balancing spring 66.
[090] As indicated by a solid line in Figs. 2 and 3, when the derailleur arm
62, accordingly
the guide pulley 63 occupies the aforesaid first position, both torques Ta, Tb
acted on the
derailleur shaft 61, i.e. the torque Ta generated by the spring force of the
tension spring 73
having one end 73a engaged with the second arm 62b and the balancing torque Tb
are kept in
their balanced state.
[091 ] Adjustment of the aforesaid balancing position so as to cause the guide
pulley 63 to
occupy the aforesaid set first position is carried out by adjusting an initial
load of the spring
force of the balancing spring 66 at the aforesaid first position. More
practically, as shown in
Fig. 7, the cap 25 is formed with a pair of insertion holes 25b comprised of
arcuate
longitudinal holes into which each of the pair of bolts B4 is inserted, and
the initial load of the
balancing spring 66 is adjusted by adjusting the position of the cap 25 in its
circumferential
direction along these insertion holes 25b.
[092] In addition, as indicated by a chain double-dashed line in Figs. 2 and
3, the torque Ta
acting on the derailleur shaft 61 and the balancing torque Tb are kept in a
balanced state also
in the case that the derailleur arm 62, accordingly the guide pulley 63
occupies the aforesaid
CA 02467512 2004-05-18
second position. Then, a spring constant of the balancing spring 66 is set in
such a way that
the guide pulley 63 may occupy the aforesaid set second position.
[093] More practically, in the case that the derailleur arm 62 occupies the
aforesaid second
position where it is rotated in a clockwise direction against the aforesaid
first position as
shown in Fig. 3 by the operating force acted on the pin 65 through the
transmission operating
mechanism 50, an angle held by the derailleur arm 62 and a holder 71 of the
tensioner 70 is
increased to cause the spring force of the tension spring 73 to be increased,
and then the
torque Ta acted on the derailleur shaft 61 is also increased.
[094] The balancing spring 66 may generate a spring force increased in
proportion to the
above-mentioned predetermined angle, because the derailleur shaft 61 is
rotated from a
position in the rotating direction at the first position to a counterclockwise
direction only by a
predetermined angle with the torque Ta increased as the derailleur arm 62 is
rotated. Then, the
spring constant of the balancing spring 66 is set in such a way that the
increased balancing
torque Tb and the increased torque Ta based on the spring force may be
balanced at the
aforesaid balancing position where the guide pulley 63 occupies the aforesaid
second position.
[095J Due to this fact, a rotating angle of the guide pulley 63 attained from
the aforesaid
first position at the aforesaid balancing position at the aforesaid second
position becomes a
31
CA 02467512 2004-05-18
small angle which is smaller by the aforesaid predetermined angle (for
example, 10°) than a
rotating angle (for example, 40°) determined in reference to a shape of
the guide hole 61 a
under an assumption in which the derailleur shaft 61 is not rotated.
[096] Then, setting of the spring forces of such a tension spring 73 and a
balancing spring
66 as described abovecauses the guide pulley 63 to be moved on the aforesaid
motion path
within the aforesaid changing-over motion range except the aforesaid first
position and the
aforesaid second position in such a way that it may occupy the same position
in the central
axis line direction AS in respect to each of the transmission sprockets 42 to
46 at each of the
transmission positions when the derailleur shaft 61 occupies the aforesaid
balancing position
and it may occupy the position spaced apart by a predetermined distance in an
outward
diameter direction.
[097] Due to this fact, when the transmission operating member 51 is operated
and the
operating element 54 connected to the wire 52 is moved to one direction (a
leftward direction
in Figs. 2 and 5) of the central axis line direction AS so as to direct toward
one end 61 a in the
storing hole 61d for carrying out a replacing of the chain toward the low
speed side, the
derailleur arm 62 is translated in the central axis line direction AS against
the spring force of
the return spring 64 on the derailleur shaft 61 rotated against the spring
force of the balancing
32
CA 02467512 2004-05-18
spring 66 within the aforesaid changing-over motion range together with the
pin 65 guided by
the guide hole 61e with the operating force acted through the moving operation
element 54
and concurrently it is rotated around the derailleur shaft 61.
[098] The chain 48 guided by the guide pulley 63 moved together with the
derailleur arm
62 occupying the transmission position determined by an operating amount of
the
transmission operating member S 1 is wound around the aforesaid operating
sprocket
alternatively selected from a group of transmission sprockets 41 to 47 in
response to the
transmission position, and the main drive sprocket 31 and the aforesaid
operating sprocket are
drivingly connected by the chain 48.
[099] Then, there will be described about an action and effects of the
preferred
embodiment constituted as described above.
[100] As shown in Figs. 2 and 3, the main drive shaft 11 rotated in a normal
rotating
direction AO by a driver operating the pedals 12 under a state in which the
transmission
sprocket 47 is selected as the aforesaid operating sprocket from a group of
transmission
sprockets 41 to 47 by the derailleur 60 having the derailleur arm 62 placed at
the aforesaid
first position, i.e. a state in which the seven-speed position is selected as
the transmission
position rotationally drives the main drive sprocket 31 through one-way clutch
32 and the
33
CA 02467512 2004-05-18
slide mechanism S. Due to this fact, the one-way clutch 32 and the slide
mechanism S are
arranged in a power transmitting path ranging from the main drive shaft 11 to
the main drive
sprocket 31.
[ 1 O1 ] The main drive sprocket 31 rotationally drives the transmission
sprocket 47, output
shaft 24 and main drive sprocket 15 through the chain 48 under a transmission
rate
determined by both sprockets 31, 47. The main drive sprocket 15 rotationally
drives the
driven sprocket 17 (refer to Fig. 1 ) and the rear wheel WR through the chain
16. The power of
the main drive shaft 11 rotationally driven by the driver is transmitted to
the output shaft 24
through the main drive sprocket 31, chain 48 and transmission sprocket 47, the
power of the
output shaft 24 is transmitted to the rear wheel WR through the aforesaid
driving force transfer
mechanism and the bicycle B runs at the seven-speed position.
[ 102] When the transmission operating member 51 is operated to select the
transmission
sprocket 41, for example, from the slower-speed transmission sprockets 41 to
46 as the
aforesaid operating sprocket so as to change-over the transmission position by
the derailleur
60, the operating element 54 moved in a leftward direction in the central axis
line direction AS
as seen in Fig. 2 by the wire 52 pushes the pin 65 to cause the pin 65 guided
by the guide hole
61 a to be moved toward the other edge 61 g of the guide hole 61 e.
34
CA 02467512 2004-05-18
[103] At this time, the derailleur arm 62 moved integrally with the pin 65 and
the guide
pulley 63 are translated in a leftward direction as seen in Fig. 2 on the
derailleur shaft 61 in
the central axis line direction AS and at the same time they are rotated
around the derailleur
shaft 61 in a clockwise direction as seen in Fig. 3, and when the derailleur
arm 62 is abutted
against the washer 67; they may occupy the first-speed position (this first-
speed position is
also the aforesaid second position) which is a transmission position indicated
by the chain
double-dotted line in Figs. 2 and 3. The state of the pin 61p at this time is
indicated in Fig. S
by the chain double-dotted line.
[ 104] Then, the chain 48 moved in a leftward direction as seen in Fig. 2
together with the
guide pulley 63 is replaced from the transmission sprocket 47 to the
transmission sprocket 41
and drivingly connected to the main drive sprocket 31 through the chain 48. At
this time, the
main drive sprocket 31 movable by the slide mechanism S in the rotary center
line direction A
is moved on the major shaft 11 a in the rotary center line direction A3 by a
partial force of the
tension of the chain 48 in the rotary center line direction A3 and occupies
the position
indicated by the chain double-dotted line in Fig. 2. In addition, the tension
pulley 72 occupies
the position for applying a tension of suitable value to the chain 48 by the
tension spring 73.
[105] In addition, when the transmission operating member 51 is operated to
cause the wire
CA 02467512 2004-05-18
52 to be loosened in such a way that the aforesaid operating sprocket is
selected from the
faster speed transmission sprockets 42 to 47 than the transmission sprocket
41, the return
spring 64 causes the derailleur arm 62 to move toward the aforesaid first
position, the guide
pulley 63 selects the fast-speed transmission sprockets 42 to 47 as the
aforesaid operating
sprocket and then the chain 48 is replaced to the aforesaid operating
sprocket. Also at this
time, the chain 48 causes the main drive sprocket 31 to move up to the
position corresponding
to a new transmission position in the rotary center line direction A3 in
concurrent with motion
of the derailleur arm 62, and then the bicycle B runs in a transmission rate
at a new
transmission position.
[ 106] In the case that the transmission position is changed over in a similar
manner, the
derailleur arm 62, guide pulley 63 and tension pulley 72 are moved toward the
desired
transmission position in response to an operation of the transmission
operating member 51
and concurrently the main drive sprocket 31 is moved on the maj or shaft 11 a
in the rotary
center line direction by a partial force of the tension of the chain 48 in the
rotary center line
direction A3. Then, the aforesaid one operating sprocket corresponding to a
desired
transmission position is selected from a group of sprockets 41 to 47 by the
derailleur 60, and
the main drive sprocket 31 and the operating sprocket are drivingly connected
through the
36
CA 02467512 2004-05-18
chain 48.
[107] In this way, the chain 48 is applied over the main drive sprocket 31 and
the aforesaid
main drive sprocket of the driven sprocket 40 along the plane crossing at a
right angle with
the rotary center line 13 of the main drive shaft 11 (this right angle
crossing plane in Fig. 2 is
in parallel with the body central line Ll), i.e. in parallel with the
aforesaid right angle crossing
plane because the main drive sprocket 31 is moved in the same direction as
that of the
translation of the derailleur arm 62 in the aforesaid changing-over motion
range while being
followed to the motion of the derailleur arm 62 for changing-over the
transmission position.
[ 108] Due to this fact, in the case of the transmission apparatus T in which
the chain 48
applied over the main drive sprocket 30 drivingly connected to the main drive
shaft 11 and the
driven sprocket drivingly connected to the output shaft 24 arranged in
parallel with the main
drive shaft 11, rowed in the rotary center line direction A4 and constituted
by the
predetermined number of transmission sprockets 41 to 47 more than the number
of the main
drive sprocket 31 is replaced by the gear shift mechanism M2, the main drive
sprocket 31 of
the main sprocket member 30 is movably supported at the main drive shaft 11 in
the rotary
center line direction A3 in such a way that the chain 48 is applied to the
main drive sprocket
31 of the main sprocket member 30 along the aforesaid right angle crossing
plane crossed at a
37
CA 02467512 2004-05-18
right angle with the rotary center line L3 and each of the transmission
sprockets 41 to 47 of
the driven sprocket member 40, i.e. the aforesaid operating sprocket, thereby
even in the case
that the chain 48 is wound around any one of the transmission sprockets 41 to
47, the main
sprocket member 30 is moved in the rotary center line direction in such a way
that the chain
48 is applied over the main sprocket member 30 and the driven sprocket member
40 along the
aforesaid right angle crossing plane in respect to the rotary center line L3,
so that the chain 48
is prevented from being inclined in respect to the aforesaid right angle
crossing plane, and the
chain 48 is prevented from being removed from the main drive sprocket 31 or
the
transmission sprockets 41 to 47 without having any relation to an inter-axis
distance between
the main drive shaft 11 and the output shaft 24 (this inter-axis distance
corresponds to a
distance between the rotary center line L3 and the rotary center line L4), and
accordingly even
when the inter-axis distance is short. Further, the chain 48 is prevented from
being removed
) from either the main drive sprocket 31 or the transmission sprockets 41 to
47 during an inertia
running state of the bicycle and when the driver stops for operating the
pedals 12 during
running of the bicycle B to cause the main drive shaft 11 to be stopped or
during a running
under a state in which the main drive shaft is being rotated in an inverse
rotating direction.
[109] Further, the main sprocket member 30 is constituted by one main drive
sprocket 31,
38
CA 02467512 2004-05-18
the main sprocket member 30 can be moved in the rotary center line direction
A3 by the slide
mechanism S arranged between the main drive shaft 11 and the main sprocket
member 30 and
at the same time the main drive sprocket member is drivingly connected to the
main drive
shaft 11, thereby the motion range of the main sprocket member 30 in the
rotary center line
direction A3 is made minimum and the size of the transmission apparatus T is
made small in
the rotary center line direction.
[110] In the case of the one-way clutch 32 arranged at the aforesaid power
transfer path
and the slide mechanism S, the slide mechanism S is arranged between the one-
way clutch 32
and the main sprocket member 30, thereby as compared with the case in which an
intermediate member, for example, the one-way clutch is present between the
slide
mechanism S and the main sprocket member 30, an inertia when the main sprocket
member
30 is moved in the rotary center line direction A3 becomes low, so that motion
of the main
sprocket member 30 is made fast during transmission and the effect of
preventing the chain
from being removed is further improved.
[111] In the case of the transmission apparatus T in which the chain 48
applied to the main
sprocket member 30 and the mufti-stage driven sprocket member 40 constituted
by a plurality
of transmission sprockets 41 to 47 is replaced by the gear shift mechanism M2
among the
39
CA 02467512 2004-05-18
plurality of transmission sprockets 41 to 47, the driven sprocket member 40
drivingly
connected to the output shaft 24 always cooperated with the rear wheel WR and
rotated is
arranged to be always rotated in an integral manner, the one-way clutch 32 for
transmitting a
rotation of the main drive shaft 11 in the normal rotating direction AO to the
main sprocket
member 30 is arranged in the aforesaid power transmitting path ranging from
the main drive
shaft 11 to the main sprocket member 30, thereby even under an inertia
operating time of the
bicycle B, the driven sprocket member 40 integrally rotated with the output
shaft 24 always
cooperated with the rear wheel WR and rotated and the main sprocket member 30
wound
around the driven sprocket member 40 and drivingly connected to it through the
chain 48
being kept in running state are in rotating state and the chain 48 is also
kept in its running
state, so that the transmission can be carried out through the gear shift
mechanism M2,
resulting in that the transmission can always be carried out as desired if the
bicycle B is in a
running state and a running performance of the bicycle B is improved.
[112] The main sprocket member 30 and the one-way clutch 32 are arranged in
coaxial
with the main drive shaft 11 and at a position where they are not overlapped
in the rotary
center line direction A3 of the main drive shaft 11, thereby the main sprocket
member 30 and
the one-way clutch 32 arranged coaxially with the main drive shaft 11 are not
restricted in
CA 02467512 2004-05-18
view of a size in the diameter direction by the main drive shaft 11 and the
main sprocket
member 30, so that a clutch performance such as a clutch capacitance or the
like can be easily
assured and they cm be arranged without producing any reduction in performance
of the
one-way clutch 32. In addition, assuring a desired rigidity of the main drive
shaft 11 is
facilitated because a shaft diameter of the shaft part 11 a of the main drive
shaft 11 is not
required to be small for arranging the one-way clutch 32.
[113] The derailleur shaft 61 for supporting in a rotatable and translatable
manner in the
central axis line direction AS the derailleur arm 62 for rotatably supporting
the guide pulley
63 having the chain 48 wound around among the plurality of transmission
sprockets 41 to 47
constituting the driven sprocket member 40 is supported at the case 20 in such
a way that its
central axis line LS becomes in parallel with the rotary center line L7 of the
guide pulley 63
and the rotary center line L4 of the driven sprocket member 40, thereby the
derailleur arm 62
is rotated around the central axis line L4 in parallel with the driven
sprocket member 40 and
the rotary center line L7 of the guide pulley 63, so that it is not necessary
to arrange any
specific member for keeping a parallel relation with the rotary center line L7
of the guide
pulley 63 and the rotary center line L4 of the driven sprocket member 40
except the derailleur
shaft 61 supporting the derailleur arm 62. As a result, the structure of the
derailleur 60 is
41
CA 02467512 2004-05-18
simplified and the number of component parts is reduced, and subsequently the
cost is
reduced.
[ 114] Further, the derailleur shaft 61 is rotatably supported at the case 20,
the derailleur 60
is provided with the balancing spring 66 for generating a balancing torque Tb
acted on the
derailleur shaft 61 in response to the spring force generated through rotation
of the derailleur
shaft 61 accompanied by a rotation of the derailleur arm 62 with the pin 65
moved while
being guided by the guide hole 61 a in response to the transmitting operation
of the
transmission operating mechanism 50 so as to cause it to be balanced with the
torque Ta acted
on the derailleur shaft 61 from the derailleur arm 62 through the pin 65,
thereby when the
chain 48 is replaced among the plurality of transmission sprockets 41 to 47,
the derailleur arm,
62 is rotated and translated against the derailleur shaft 61 through the pin
65 and at the same
time the derailleur shaft 61 is rotated by the torque Ta acted on the
derailleur shaft 61 from the
derailleur arm 62 through the pin 65, although the balancing torque Tb
generated by the
spring force of the balancing spring 66 produced in response to the aforesaid
rotation is
balanced with the torque Ta and the guide pulley 63 occupies the predetermined
replacing
position. At this time, the derailleur shaft 61 is not fixed to the case 20,
but its rotation is
merely restricted by the balancing spring 66, so that normally an excessive
outer force
42
CA 02467512 2004-05-18
exceeding an external force acted on the derailleur arm 62, for example, an
excessive tension
generated when the chain 48 is engaged with the driven sprocket member 40
during a
transmitting operation while the bicycle B is being moved rearwardly under a
state in which
the driver rides off the bicycle and the chain is rotated together with the
driven sprocket
member 40 while being locked causes the excessive torque to be generated in
the derailleur
arm 62 and when the excessive torque acts on the pin 61e and the derailleur
shaft 61, the
derailleur shaft 61 deforms the balancing spring 66 and rotates, resulting in
that the excessive
torque is loosened and the excessive torque acted on the derailleur arm 62,
pin 65 and
derailleur shaft 61 is reduced, these members are prevented from being
deformed with the
excessive force and so the derailleur 60 and subsequently the transmission
apparatus T show
an improved durability
[115] The output shaft 24 at the transmission apparatus T can be easily
changed in its
arrangement at the transmission apparatus T and a degree of freedom in its
arrangement may
also be increased in order to adapt for changing in positions of the body
frame F or pivot shaft
7 because the chain 48 is used for drivingly connecting the aforesaid sprocket
drivingly
connected to the output shaft 24 having the chain 16 drivingly connected and
the main drive
sprocket 31.
43
CA 02467512 2004-05-18
[116] There will be described about a modified configuration in regard to the
preferred
embodiment in which a part of the aforesaid preferred embodiment is changed as
follows.
[117] The case 20 of the transmission apparatus T may be made of synthetic
resin. Further,
it is available that the transmission apparatus T is not provided with the
case 20 and in this
case, the main drive shaft 11, output shaft 24 and derailleur 60 are fixed to
the body frame F
or supported at the body frame F through a supporting member such as a bracket
and the like
integrally formed with the body frame F.
[118] It may also be applicable that a linking loop is used as the endless
transmission
linking loop for a transmission operation and further pulleys are used as the
driving rotating
member and the driven rotating member. In addition, it may also be applicable
that the
endless linking loop is used as an output endless linking loop for the rear
wheel WR and
pulleys are used as the output driving rotating member and the output driven
rotating member.
[119] In the aforesaid preferred embodiment, although the main drive sprocket
30 is
constituted by the main drive sprocket 31 acting as one rotary element, it may
also be
applicable that the main drive sprocket is constituted by a plurality of main
drive sprockets
arranged in the rotary center line direction A3 and having different tip
diameters.
[120] It is also applicable that the aforesaid engaging mechanism arranged at
the slide
44
CA 02467512 2004-05-18
mechanism S is a spline constituted by several protrusions formed at the outer
circumferential
surface of the inner cylinder 34 and the inner circumferential surface of the
outer cylinder 35
and several grooves to which these protrusions are fitted.
[121J In the case that the main drive sprocket member is separate from the
main drive shaft
11 and coaxially arranged at the intermediate rotating shaft rotationally
driven by the main
drive shaft 11 through the transmission mechanism, one-way clutch 32 is
arranged in the
power transfer path ranging from the main drive shaft 11 to the aforesaid main
drive sprocket
member, for example, between the aforesaid intermediate rotating shaft and the
main drive
sprocket member.
[122J Although the present invention has been described herein with respect to
a specific
illustrative embodiment thereof, the foregoing description is intended to be
illustrative, and
not restrictive. Those skilled in the art will realize that many modifications
of the preferred
'v
embodiment could be made which would be operable. All such modifications which
are
within the scope of the claims are intended to be within the scope and spirit
of the present
invention.
