U.S. patent application number 09/752153 was filed with the patent office on 2002-07-04 for automatic transmission for a cycle, such as a bicycle, and a cycle having such a transmission.
This patent application is currently assigned to The Massachusetts Institute of Technology. Invention is credited to Lerman, Harry H., Lerman, Victor S., Otten, David M..
Application Number | 20020084618 09/752153 |
Document ID | / |
Family ID | 25025115 |
Filed Date | 2002-07-04 |
United States Patent
Application |
20020084618 |
Kind Code |
A1 |
Lerman, Victor S. ; et
al. |
July 4, 2002 |
AUTOMATIC TRANSMISSION FOR A CYCLE, SUCH AS A BICYCLE, AND A CYCLE
HAVING SUCH A TRANSMISSION
Abstract
A shifting mechanism for a bicycle or other wheeled cycle has at
least two gear wheels, of which at least one is segmented. The
segments are movable into and out of a driving position. Motion of
the segments occurs at a circumferential location out of the
driving zone, at a location where the driving band, typically a
chain, is not contacting the segment. The shifting mechanism can be
provided at the front chain ring, or at the rear, gear sprocket.
For a front chain wheel, the free zone is generally the rearward
half of the chain ring, while for the rear gear sprocket, the free
zone is generally the forward half. The moving segments can be
toothed gates which flip perpendicularly to the plane in which the
chain resides. The gates may be actuated by a moving mechanism
powered by an actuator, such as a D.C. motor, under control of a
signal processor, such as a microprocessor. The signal processor
also takes as an input a speed signal based on the rotational speed
of the cycle wheels, or the cadence of the pedal or a combination
thereof.
Inventors: |
Lerman, Victor S.; (Malden,
MA) ; Lerman, Harry H.; (Everett, MA) ; Otten,
David M.; (Newton, MA) |
Correspondence
Address: |
STEVEN J WEISSBURG
238 MAIN STREET
SUITE 303
CAMBRIDGE
MA
02142
|
Assignee: |
The Massachusetts Institute of
Technology
|
Family ID: |
25025115 |
Appl. No.: |
09/752153 |
Filed: |
December 29, 2000 |
Current U.S.
Class: |
280/261 ;
280/281.1 |
Current CPC
Class: |
B62M 1/36 20130101; B62M
9/14 20130101; B62M 9/08 20130101 |
Class at
Publication: |
280/261 ;
280/281.1 |
International
Class: |
B62M 001/02 |
Claims
Having described the invention, what is claimed is:
1. A transmission component for a cycle having a driving crank and
a driven wheel, torque being transmitted from said driving crank
through a bracket, that is coupled thereto, to said wheel by an
endless power band that engages said transmission component at a
driving zone and that is free from said transmission component at a
free zone, said transmission component being coupled to said
bracket and comprising a variable configuration ring assembly that
comprises: a. a support; and b. coupled to said support, a
plurality of ring components, each of which is movable from a
driving position to a non-driving position, further wherein each of
said ring components comprises at least one band engaging elements
around a perimeter, said ring components arranged such that: i. if
said ring component is in said driving position, said band engaging
elements: A. form an outermost, segmented band ring; B. are driven
circumferentially if said crank is moved in a driving direction; C.
lie in a driving plane; and D. engage said band in said driving
zone but are free from said band in said free zone; and ii. if said
ring component is not in said driving position, said band engaging
elements: A. lie out of said driving plane; and B. are free from
said band in both said driving zone and in said free zone.
2. The transmission component of claim 1, further comprising, for
each said ring component, a couple to said support that constrains
relative motion of said ring component such that motion of said
ring component from said non-driving position to said driving
position has a vector component that is perpendicular to said
driving plane.
3. The transmission component of claim 2, further comprising a ring
component mover, arranged and operative to move at least one of
said ring components from said non driving position to said driving
position only when said ring component is in said free zone.
4. The transmission component of claim 1, further comprising a
radially innermost band ring, having a plurality of band engaging
elements around a perimeter, said innermost band ring being coupled
by said bracket to said driving crank such that said band engaging
elements: a. are driven circumferentially if said crank is driven
circumferentially; b. lie in said driving plane; and c. engage said
band in said driving zone and are free from said band in said free
zone, if said innermost band ring engages said band.
5. The transmission component of claim 1, said cycle comprising a
bicycle, said wheel comprising a rear wheel of said bicycle.
6. The transmission component of claim 1, said endless band
comprising a roller chain, said band engaging elements sized and
shaped to engage links of said chain.
7. The transmission component of claim 1, said endless band
comprising a posi-drive type belt, said band engaging elements
sized and shaped to engage said posi-drive type belt.
8. The transmission component of claim 1, each said ring components
arranged such that when engagement with said band commences, said
ring component is fully in said driving position and is not moving
from said non-driving position to said driving position.
9. The transmission component of claim 4, said outermost plurality
of ring components, designated "gates," further comprising, a gate
mover, operative to move at least one of said gates, only where
said at least one gate is in said free zone: a. from said
non-driving position to said driving position; and b. from said
driving position to said non-driving position.
10. The transmission component of claim 4, said innermost band ring
arranged relative to said outer band ring such that if said
innermost band ring engages a band, and said ring components of
said outer band ring are sequentially moved from said non-driving
position to said driving position, then said band transfers from
said innermost band ring to said outer band ring by engagement with
said moved ring components.
11. The transmission component of claim 10, said innermost band
ring further arranged relative to said outer band ring such that if
said outer band ring engages a band, and said ring components of
said outer band ring are sequentially moved from said driving
position to said non-driving position, then said band transfers
from said outer band ring to said innermost band ring.
12. The transmission component of claim 9, further comprising, for
each of said plurality of gates, a hinge that couples said gate to
said support.
13. The transmission component of claim 9, said plurality of gates
being located such that said segmented outermost band ring
circumscribes said innermost band ring if said outermost gates are
in said driving position.
14. The transmission component of claim 13, further comprising: a.
a radially intermediate segmented band ring, carried by said
support, so that it is also driven circumferentially if said crank
is driven circumferentially, said intermediate band ring comprising
a plurality of intermediate movable gates, each of said plurality
of intermediate gates carrying at least one band engaging elements
along a peripheral region, each of said plurality of intermediate
gates being movable from a non-driving position with said band
engaging elements out of said driving plane, to a driving position
with said band engaging elements in said driving plane, such that
said intermediate band engaging elements engage said band in said
driving zone and are free from said band in said free zone if said
intermediate band ring engages said band; and b. for said plurality
of intermediate gates, a gate mover, operative to move each said
intermediate gate, only where said gate is in said free zone: i.
from said non-driving position to said driving position; and ii.
from said driving position to said nondriving position.
15. The transmission component of claim 14, said plurality of
intermediate gates located such that said intermediate segmented
band ring circumscribes said innermost band ring, and is
circumscribed by said outermost segmented band ring if said
intermediate and outermost movable gates are in said driving
position.
16. The transmission component of claim 9, said gate mover being
movable, and each of said gates comprising a gate placer, arranged
to be contacted by said gate mover.
17. The transmission component of claim 16, said gate placer
comprising an angled ramp, carried by said gate.
18. The transmission component of claim 16, each of said gates
comprising a gate picker, arranged to be contacted by said gate
mover.
19. The transmission component of claim 18, said gate picker
comprising an angled ramp, carried by said gate.
20. The transmission component of claim 18, said gate mover
comprising a placer trigger that is movable to contact said gate
placer of a gate when said gate is in said free zone and a picker
trigger that is movable to contact said gate picker when said gate
is in said free zone.
21. The transmission component of claim 9, said gate mover being
movable at selectable times to a placing position in which it
contacts said gate as said gate passes by said gate mover, thereby
causing said gate to move from said non-driving position to said
driving position.
22. The transmission component of claim 21, said gate mover being
movable to said placing position by a cable linkage.
23. The transmission component of claim 21, said gate mover being
movable to said placing position at selectable times based on a
rotational velocity of said driven wheel.
24. The transmission component of claim 23, further comprising: a.
a sensor which, upon activation, generates a signal that
corresponds to rotational velocity of said driven wheel; and b.
coupled to said sensor, an outer ring actuator, actionable to move
said gate mover to said placing position at times that said
rotational velocity of said driven wheel increases to an outermost
upshift velocity.
25. The transmission component of claim 24, said gate mover further
being movable at selectable times to a picking position in which it
contacts said gate as said gate passes by said gate mover, thereby
causing said gate to move from said driving position to said
non-driving position.
26. The transmission component of claim 25, said gate mover being
movable to said picking position at selectable times based on a
rotational speed of said driven wheel.
27. The transmission component of claim 26, said outermost actuator
further actionable to move said gate mover to said picking position
at times that said rotational velocity of said driven wheel
decreases to an outermost downshift velocity.
28. The transmission component of claim 27, wherein said outermost
downshift velocity is less than said outermost upshift
velocity.
29. The transmission component of claim 24, further comprising: a.
a radially intermediate segmented band ring, carried by said
support and also driven circumferentially when said crank is driven
circumferentially, said intermediate band ring comprising a
plurality of intermediate movable gates, each carrying at least one
band engaging elements along a peripheral region, each of said
plurality of intermediate gates being movable from a non-driving
position with said at least one band engaging elements out of said
plane, to a driving position with said band engaging elements in
said driving plane, such that said intermediate band engaging
elements engage said band in said driving zone and are free from
said band in said free zone if said intermediate band ring engages
said band; and b. for said plurality of intermediate gates, at
least one intermediate gate mover, operative to move said
intermediate gate, only where said gate is in said free zone: i.
from said non-driving position to said driving position; and ii.
from said driving position to said nondriving position.
30. The transmission component of claim 29, said intermediate gate
mover further being movable at selectable times to a placing
position in which it contacts an intermediate gate as said
intermediate gate passes by said intermediate gate mover, thereby
causing said intermediate gate to move from said non-driving
position to said driving position.
31. The transmission component of claim 30, said intermediate gate
mover being movable to said placing position at selectable times
based on a rotational velocity of said driven wheel.
32. The transmission component of claim 31, further comprising,
coupled to said sensor, an intermediate ring actuator, actionable
to move said intermediate gate mover to said placing position at
times that said rotational velocity of said driven wheel increases
to an intermediate upshift velocity.
33. The transmission component of claim 32, said intermediate
upshift velocity being less than said outermost upshift
velocity.
34. The transmission component of claim 32, said intermediate gate
mover further being movable at selectable times to a picking
position in which it contacts an intermediate gate as said
intermediate gate passes by said intermediate gate mover, thereby
causing said intermediate gate to move from said driving position
to said non-driving position.
35. The transmission component of claim 34, said intermediate gate
mover being movable to said picking position at selectable times
based on a rotational velocity of said driven wheel.
36. The transmission component of claim 35, said intermediate
actuator further actionable to move said intermediate gate mover to
said picking position at times that said rotational velocity of
said driven wheel decreases to an intermediate downshift
velocity.
37. The transmission component of claim 24, further comprising a
controller that controls actuation of said outer ring actuator.
38. The transmission component of claim 37, said outer ring
actuator comprising a D.C. motor.
39. The transmission component of claim 37, said outer ring
actuator comprising a servo motor.
40. The transmission component of claim 37, said outer ring
actuator comprising a solenoid.
41. The transmission component of claim 38, said D.C. motor
comprising metal wipers.
42. A transmission for a bicycle, the transmission comprising a
variable configuration gear wheel, having components that move
relative to each other from a first position to a second position,
where, in said second position, said movable components engage a
bicycle chain in a driving position, said movable component
configured and arranged so that said relative motion takes place
only in a free zone where said chain and movable components are
free of each other.
43. The transmission of claim 42, said movable components arranged
such that when any of said movable components engages said chain,
said movable component is stationary relative to all except, at
most, one other of said movable components.
44. The transmission of claim 42, said variable configuration gear
wheel comprising a front chain wheel, said free zone comprising a
zone behind said chain wheel, generally between it and a rear wheel
of said bicycle.
45. The transmission of claim 42, said variable configuration gear
wheel comprising a rear sprocket wheel, said free zone comprising a
zone ahead of said sprocket wheel, generally between it and a chain
wheel of said bicycle.
46. The transmission of claim 42, said movable component being
movable to said second position along a path having a component
that is perpendicular to a plane in which said chain lies.
47. The transmission of claim 42, further comprising a mover
mechanism to move each of said movable components from said first
position to said second position.
48. The transmission of claim 47, further comprising a mover
mechanism to move each of said movable components from said second
position to said first position.
49. A cycle, comprising: a. a frame; b. front and rear wheels; and
c. coupled to said frame, a transmission, comprising a variable
configuration gear wheel, having components that move relative to
each other from a first position to a second position, where, in
said second position, said movable components engage a cycle chain
in a driving position, said movable component configured and
arranged so that said relative motion takes place only in a free
zone where said chain and movable components are free of each
other.
50. The cycle of claim 49, said variable configuration gear wheel
comprising a front chain wheel, said free zone comprising a zone
behind said chain wheel, generally between it and said rear
wheel.
51. The cycle of claim 49, said variable configuration gear wheel
comprising a rear sprocket wheel, said free zone comprising a zone
ahead of said sprocket wheel, generally between it and said front
wheel.
Description
BACKGROUND
[0001] This invention relates to human powered vehicles in general,
and to automatic transmissions therefor, in particular.
[0002] Human powered cycles, such as bicycles, and some tricycles,
often have a variable speed transmission. With known bicycles, such
as shown in FIG. 1, there are various types of variable
transmission. Internal rear hub transmissions, typically 3 speed,
are known. With such transmissions, the rider rotates pedals 10
that are connected to a chain ring 12 through a crank 11, which, in
turn, through a chain 14, is connected to a rear wheel sprocket 16.
The sprocket is connected through a variable internal hub
transmission (not shown) to the wheel 18. (FIG. 1 is a composite,
showing aspects of various, different types of prior art
transmissions. It does not show the internal hub transmission or a
cable thereto, but, rather, shows a type of rear wheel transmission
that is described below. Since the internal hub type transmission
is well known, and not germane to the invention, it is not shown
specifically. FIG. 1 is used herein only to show where such known,
internal hub transmissions reside.) The internal workings of the
hub change according to controls manually manipulated by the user,
such as through a handlebar-mounted lever that connects to the hub
through a cable.
[0003] Another popular type of known transmission, such as shown
with reference to FIG. 1, employs a multi-sprocket rear cartridge
18, for instance mounted on the rear hub 16, having several,
typically between three and eight variable diameter sprockets 20. A
rear derailleur 22 engages the chain 14, as described above, and,
again under manual control of the operator, typically through a
cable 24, moves the chain from engagement with one of the sprockets
to another. By changing the active sprocket to one with a different
diameter, the gear ratio of the operable transmission elements is
changed. A larger rear sprocket 20 reduces the effort required to
rotate the rear wheel 26 against a load, and is typically referred
to as a "lower gear." A smaller rear sprocket 20 increases the
effort required to rotate the rear wheel against a load, but also
increases the circumferential distance covered by the rear wheel
for a single rotation of the pedals 10, and is referred to as a
"higher gear." Typically, the cable moves the derailleur such that
it directs the chain from a higher to a lower gear while a spring
within the derailleur returns the chain from a lower to a higher
gear when the user relaxes the tension on the cable by moving a
lever.
[0004] A similar type of transmission also employs a set of
sprockets having different diameters, but, rather than being
mounted on the rear hub, such varying diameter sprockets 28 are
coupled directly to the pedal assembly, so that one rotation of the
pedals causes one full rotation of the front sprockets 28. The
sprockets are typically referred to as chain ring sets. A front
derailleur 30 engages the chain 14, and, again under manual control
of the operator, typically through a cable (not shown), moves the
chain 14 from engagement with one of the chain rings 32 to another
34. By changing the active chain ring to one with a different
diameter, the gear ratio of the operable transmission elements is
changed. A larger 32 front chain ring 28 increases the effort
required to rotate the rear wheel 26 against a load, and is
typically referred to as a "higher gear." A smaller 34 front chain
ring 28 decreases the effort required to rotate the rear wheel
against a load, but also decreases the circumferential distance
covered by the rear wheel for a single rotation of the pedals 14,
and is referred to as a "lower gear." Typically, the cable moves
the derailleur such that it directs the chain from a lower to a
higher gear while a spring within the derailleur returns the chain
from a higher to a lower gear when the user relaxes the tension on
the cable by moving a lever.
[0005] Thus, a higher gear is obtained by engaging a smaller rear
sprocket 18 or a larger front chain ring 28. A lower gear is
obtained by engaging a larger rear sprocket or a smaller front
chain ring.
[0006] Often, bicycles use both a front and rear derailleur type
transmission, thereby obtaining a large number of effective gear
ratios, equal to the product of the number of rear sprockets 18
times the number of front chain rings 28. However, often, some of
the gear ratio combinations are very nearly equal to others of the
combinations, and often the extreme combinations, such as the
largest rear sprocket and the largest front chain ring (which would
result in an intermediate gear ratio) are not comfortably obtained
without the chain rubbing excessively on the chain ring and
sprocket. Thus, a nominally eighteen speed transmission (six rear
sprockets and three front chain rings) might have only eight to ten
significantly different gear ratios.
[0007] There are other types of transmissions also, which are known
to the art.
[0008] All of the above mentioned transmissions are typically
available in a manual embodiment, in which the user decides when to
change gears ("shift gears") and does so by manually moving some
element of the transmission system. Typically, the movable element
is a lever near the front of the bicycle. Over the years, many
different types of levers have been used. (For purposes of
illustration, only, several types are shown in FIG. 1. Only one
type would be present for any actual bicycle.) A popular three
speed-internal hub transmission used a single handle mounted lever
(not shown). Other cartridge and chain ring models use levers 40
mounted on the handle bars, or 42 on the down tube and 44 at the
ends of the handle bar tubes (both lever and rotary types). A
relatively recent configuration incorporates the gear shift levers
into handles 46 that are also part of the braking assembly. With
some models, a unitary lever actuates both a brake and a gear
shift, while in others, tandem, nested levers are used, one for
braking and one for shifting. Some shifting lever mechanisms use
one lever for shifting from a lower gear to a higher gear, and
another for the reverse direction.
[0009] A problem with all of the conventional transmissions that
use a rear cartridge 18 or/and a front set of chain rings 28, is
that shifting the chain from one toothed gear wheel to another,
when shifting from a higher to a lower gear, such as when climbing
a hill, typically occurs at a time when the user wants to be
applying power to the transmission. However, if power is applied at
the wrong moment, as the chain is intermediate between one ring and
another, the next chain ring does not pick up the chain, and the
shifting mechanism malfunctions. The result is grinding and wear of
all of the components, as well as loss of power and momentum, which
often necessitates shifting to an even lower gear. There are some
semi-automated shifting mechanisms which delay the actual shifting
until the components are aligned properly to avoid missing.
[0010] One reason that gear missing occurs is that the chain is
being moved adjacent the gear wheels, right at the circumferential
location around the gear wheel where the chain engages the gear
wheel, and where power is transmitted from the gear wheel to the
chain (front gear wheels), or vice versa (rear gear wheels). In
other words, the chain is removed from the first gear wheel within
the driving zone, and is deposited onto the next gear wheel within
the driving zone. As shown in FIG. 1, the "driving zone" is roughly
the forward half of the chain ring (for a front chain ring),
indicated between the arrows D.sub.Z. (For a rear chain ring
sprocket, the driving zone is roughly the rearward half.)
[0011] Force is generated between the chain and the chain ring in
part due to the torque applied by the user pushing on the pedals,
and in part by the tension in the chain, which is established by a
spring in the rear derailleur 22. Thus, as the chain is moving over
toward the chain ring, torque is being applied by the pedals to the
chain ring. If there is no engagement between the chain and the
chain ring, then no load resists the torque and the chain wheel
just spins. Or more commonly, if the engagement is positive, but
less than some minimum degree, the chain is not retained by the
chain wheel, and the chain wheel spins while the teeth grind
against the chain links, thereby eventually damaging both, as well
as failing to apply power to the task of moving the cycle.
[0012] Another drawback with conventional systems is that the user
must decide when to shift. Many users are not skilled at making
such decisions, and make the decision at the wrong time. Further,
the user must manually make the move. This requires, in most cases,
removing the hand from the normal driving position, and moving it
to a shifting mechanism. In the case of down tube, and centrally
mounted handle bar shifters, the shifting hand can no longer
control the handlebars. This is the reason for the popularity of
bar end and brake mechanism shifters. However, bar end shifters are
often very stiff, and awkward to actuate. Brake mechanism shifters
are very expensive, fragile, and mechanically complicated.
[0013] Automatic shifting transmissions have been proposed with
many different forms of mechanisms, attempting to solve the
foregoing problems. None have been commercially successful, and the
reasons are too many and various to explore here. Many have
mechanisms that actuate in the driving zone and must move against
the resistance of a driving band (typically a chain) as power is
applied to it by the user. Many have complicated or delicate
mechanisms that cannot withstand the harsh environment cycles,
particularly bicycles, encounter. Many cannot be adequately
governed, or require large forces to shift the gears.
[0014] Another drawback of many of the known automatic shifting
mechanisms, is that they can not be retrofitted onto the millions
of existing bicycles. In fact, some designs cannot even be used on
a conventional bicycle frame, but require special configurations of
the supports and stays.
[0015] Thus, the several objects of the present invention include
to provide a shifting mechanism for a human powered wheeled cycle,
particularly a bicycle, which is not prone to slipping when
shifting. Another object is to provide a shifting mechanism that
can be simply and reliably automated, so that the user need not
decide when to shift, or displace his/her hands from the driving
position to make the shift. Another object of the invention is to
provide a shifting mechanism that can be automated, which can be
retrofitted onto existing bicycles, and that can be incorporated
into new bicycles with standard frames. Another object of the
invention is to provide a transmission with the foregoing
properties, which is economical to manufacture and maintain.
SUMMARY
[0016] In general, according to the present invention, a shifting
mechanism for a cycle, such as a bicycle, is provided that has at
least two gear wheels, of which at least one is segmented. The
segments are movable into and out of a driving position. Motion of
the segments occurs at a circumferential location out of the
driving zone, at a location where the driving band, typically a
chain, is not contacting the segment. The shifting mechanism can be
provided at the front chain ring, or at the rear, gear sprocket.
For a front chain wheel, the free zone is generally the rearward
half of the chain ring, while for the rear gear sprocket, the free
zone is generally the forward half. The moving segments can be
toothed gates which flip perpendicularly to the plane in which the
chain resides. The gates may be actuated by a moving mechanism
powered by an actuator, such as a D.C. motor, under control of a
signal processor, typically a microprocessor. The signal processor
also takes as an input a speed signal based on the rotational speed
of the cycle wheels, or the cadence of the pedal or a combination
thereof.
[0017] A preferred embodiment of the invention is a transmission
for a bicycle, the transmission comprising a variable configuration
gear wheel, having components that move relative to each other from
a first position to a second position, where, in the second
position, the movable components engage a bicycle chain in a
driving position. The movable components are configured and
arranged so that the relative motion takes place only in a free
zone where the chain and movable components are free of each other.
The movable components are arranged such that when any movable
component engages the chain, the movable component is stationary
relative to all except, at most, one other of the movable
components. The variable configuration gear wheel may be a front
chain wheel, in which case the free zone is a zone behind the chain
wheel, generally between it and a rear wheel of the bicycle.
Alternatively, the variable configuration gear wheel may be a rear
sprocket wheel, in which case the free zone is a zone ahead of the
sprocket wheel, generally between it and a chain wheel of the
bicycle.
[0018] The movable component is movable to the second position
along a path having a component that is perpendicular to a plane in
which the chain lies. The transmission also includes a mover
mechanism to move each of the movable components to the second
position. Either the same, or another mover mechanism moves each of
the movable components from the second to the first position.
[0019] Another preferred embodiment of the invention is a
transmission component for a cycle having a driving crank and a
driven wheel, torque being transmitted from the driving crank
through a bracket, that is coupled thereto, to the wheel by an
endless power band that engages the transmission component at a
driving zone and that is free from the transmission component at a
free zone. The transmission component is coupled to the bracket and
comprises a variable configuration ring assembly that comprises: a
support and, coupled to the support, a plurality of ring
components. Each ring component is movable from a driving position
to a non-driving position. Each of the ring components comprises at
least one band engaging elements around a perimeter. The ring
components are arranged such that, if the ring component is in the
driving position, then the band engaging elements: form an
outermost, segmented band ring; are driven circumferentially if the
crank is moved in a driving direction; lie in a driving plane; and
engage the band in the driving zone but are free from the band in
the free zone. The ring components are also arranged such that, if
the ring component is not in the driving position, then the band
engaging elements lie out of the driving plane and are free from
the band in both the driving zone and in the free zone.
[0020] Typically, each ring component has a couple to the support
that constrains relative motion of the ring component such that
motion of the ring component from the non-driving position to the
driving position has a vector component that is perpendicular to
the driving plane.
[0021] A version of this embodiment of the invention further has a
ring component mover, arranged and operative to move at least one
of the ring components from the non driving position to the driving
position only when the ring component is in the free zone. There
may be a single mover for each ring component, one for all, or more
than one mover may handle some but not all of the ring
components.
[0022] A typical embodiment of the invention further comprises a
radially innermost band ring, having a plurality of band engaging
elements around a perimeter. The innermost band ring is coupled by
the bracket to the driving crank such that the band engaging
elements: are driven circumferentially if the crank is driven
circumferentially; lie in the driving plane; and engage the band in
the driving zone and are free from the band in the free zone, if
the innermost band ring engages the band.
[0023] In a very useful embodiment of the invention, the cycle is a
bicycle, and the wheel comprises a rear wheel of the bicycle.
Typically, the endless band comprising a roller chain, the band
engaging elements being sized and shaped to engage links of the
chain. Alternatively, the endless band may be a posi-drive type
belt, the band engaging elements being sized and shaped to engage
the posi-drive type belt.
[0024] In many embodiments, the ring components are arranged such
that when engagement with the band commences, the ring component is
fully in the driving position and is not moving from the nondriving
position to the driving position.
[0025] According to another embodiment of the invention, the
outermost plurality of ring components are designated "gates." The
invention further comprises, a gate mover, operative to move at
least one of the gates, only where the at least one gate is in the
free zone: from the non-driving position to the driving position;
and from the driving position to the non-driving position. As
mentioned above, there may be one gate mover for all of the
outermost gates, or one for each, or more than one, each of which
handles some, but not all, of the gates.
[0026] The innermost band ring is arranged relative to the outer
band ring such that if the innermost band ring engages a band, and
the ring components of the outer band ring are sequentially moved
from the non-driving position to the driving position, then the
band transfers from the innermost band ring to the outer band ring
by engagement with the moved ring components. Conversely, if the
outer band ring engages a band, and the ring components of the
outer band ring are sequentially moved from the driving position to
the non-driving position, then the band transfers from the outer
band ring to the innermost band ring.
[0027] In a preferred embodiment, a hinge couples each gate to the
support.
[0028] The plurality of gates are typically located such that the
segmented outermost band ring circumscribes the innermost band ring
if the outermost gates are in the driving position.
[0029] According to an embodiment of the invention that provides
more speed possibilities, the transmission further comprises a
radially intermediate segmented band ring, carried by the support,
so that it is also driven circumferentially if the crank is driven
circumferentially. The intermediate band ring comprises a plurality
of intermediate movable gates, each of the plurality of
intermediate gates carrying at least one band engaging elements
along a peripheral region. Each of the plurality of intermediate
gates are movable from a non-driving position with the band
engaging elements out of the driving plane, to a driving position
with the band engaging elements in the driving plane, such that the
intermediate band engaging elements engage the band in the driving
zone and are free from the band in the free zone if the
intermediate band ring engages the band. For the plurality of
intermediate gates, there is at least one gate mover, operative to
move each the intermediate gate, only where the gate is in the free
zone. The gate mover is operative to move the gates from the
non-driving position to the driving position and from the driving
position to the nondriving position. The plurality of intermediate
gates are located such that the intermediate segmented band ring
circumscribes the innermost band ring, and is circumscribed by the
outermost segmented band ring if the intermediate and outermost
movable gates are in the driving position.
[0030] In a typical preferred embodiment, the gate mover is
movable. Each of the gates comprises a gate placer, arranged to be
contacted by the gate mover. The gate placer may comprise an angled
ramp, carried by the gate. Each of the gates also typically
comprises a gate picker, which may also be an angled ramp carried
by the gate, arranged to be contacted by the gate mover. The gate
mover may have a placer trigger that is movable to contact the gate
placer of a gate when the gate is in the free zone and a picker
trigger that is movable to contact the gate picker when the gate is
in the free zone.
[0031] In still another preferred embodiment, the gate mover is
movable at selectable times to a placing position in which it
contacts the gate as the gate passes by the gate mover, thereby
causing the gate to move from the non-driving position to the
driving position. The gate mover may be movable to the placing
position by a cable linkage. More typically, the gate mover is
movable to the placing position at selectable times based on a
rotational velocity of the driven wheel. In such a case, the
invention further comprises a sensor which, upon activation,
generates a signal that corresponds to rotational velocity of the
driven wheel. Coupled to the sensor is an outer ring actuator,
actionable to move the gate mover to the placing position at times
that the rotational velocity of the driven wheel increases to an
outermost upshift velocity.
[0032] In a specifically preferred embodiment of the invention, the
gate mover is further movable at selectable times to a picking
position in which it contacts the gate as the gate passes by the
gate mover, thereby causing the gate to move from the driving
position to the non-driving position. The gate mover is also
movable to the picking position at selectable times based on a
rotational speed of the driven wheel. Typically, the outermost
actuator is further actionable to move the gate mover to the
picking position at times that the rotational velocity of the
driven wheel decreases to an outermost downshift velocity. It is
helpful if the outermost downshift velocity is less than the
outermost upshift velocity.
[0033] In an embodiment, as described above, having an outermost,
innermost, and intermediate band rings, the intermediate gate mover
is also typically movable, for both picking and placing, by an
intermediate gate actuator at times based on wheel velocity, with
upshift and downshift velocities that are coordinated with the
upshift and downshift velocities for the outermost band ring. The
intermediate upshift velocity is less than the outermost upshift
velocity.
[0034] According to another beneficial aspect of the invention,
there is a controller that controls actuation of the outer ring
actuator. The controller may be a microprocessor. The ring actuator
may be a D.C. motor, a servo motor, or a solenoid. A particularly
useful type of D.C. motor is a small, 1.5 volt motor having copper
wipers.
[0035] A preferred aspect of the invention is a transmission for a
cycle, according to any of the embodiments described above, either
as a retrofit or as an original equipment feature. Also an aspect
of the invention is an entire bicycle, or other type cycle,
employing any of the embodiments of the transmission of the
invention described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] These and other features, aspects, and advantages of the
present invention will become better understood with regard to the
following description, appended claims and accompanying drawings,
where:
[0037] FIG. 1 (Prior art) is an idealized representation of a
conventional touring bicycle frame, equipped with front and rear
derailleurs, and front and rear gear sprocket sets, along with
various gear shifting levers;
[0038] FIG. 2 is a schematic representation of a portion of an
embodiment of the invention, showing a three ring front chain ring
set, with movable gates, viewed from the direction of the smaller
diameter chain ring face;
[0039] FIG. 3 is a schematic representation of a portion of the
embodiment of the invention shown in FIG. 2, from the view of the
opposite, larger diameter chain ring face, showing an embodiment of
a gate actuator and gate placer/picker;
[0040] FIGS. 4A-4E are schematic representations of a portion of a
chain ring set of an embodiment of the invention; where:
[0041] FIG. 4A shows the chain being carried by the smallest chain
ring;
[0042] FIG. 4B shows the chain being carried by the smallest chain
ring with an intermediate gate moved into a driving position, while
two intermediate gates and two largest diameter gates remain in a
non-driving position;
[0043] FIG. 4C shows the chain being carried by the intermediate
chain ring configuration while two largest diameter gates remain in
a non-driving position;
[0044] FIG. 4D shows the chain being carried by the largest chain
ring with a largest gate moved into a driving position, while one
largest diameter gate remains in a non-driving position;
[0045] FIG. 4E shows the chain being carried by the largest
diameter chain ring configuration;
[0046] FIG. 5A shows schematically a gate and gate mover, as the
gate mover contacts the gate just before the gate moves from a
non-driving position to a driving position;
[0047] FIG. 5B shows schematically a gate and gate mover, as the
gate mover contacts the gate just after the gate moves from a
non-driving position to a driving position;
[0048] FIG. 5C shows schematically a gate and gate mover, as the
gate mover contacts the gate just before the gate moves from a
driving position to a non-driving position;
[0049] FIG. 5D shows schematically a gate and gate mover, as the
gate mover contacts the gate just after the gate moves from a
driving position to a non-driving position;
[0050] FIG. 6A shows a gate of an embodiment of the present
invention, from a side view;
[0051] FIG. 6B shows a top view of a gate of an embodiment of the
present invention, shown in FIG. 6A;
[0052] FIG. 6C shows an end view of a gate of an embodiment of the
present invention, shown in FIG. 6A;
[0053] FIG. 7 shows schematically, from below the cycle, a gate and
gate mover, similar to that shown in FIG. 5A, except that a worm
gear and worm transmission is used, rather than links, as the gate
mover contacts the gate just before the gate moves from a
non-driving position to a driving position;
[0054] FIG. 8 shows schematically the worm embodiment of a gate and
gate mover, shown in FIG. 7, in a configuration similar to that
shown in FIG. 5C, as the gate mover contacts the gate just before
the gate moves from a driving position to a non-driving
position;
[0055] FIG. 9 shows schematically the worm embodiment of gate and
gate mover shown in FIGS. 7 and 8, from a side view, as viewed from
the non-chain side, such as in FIG. 3;
[0056] FIG. 10 shows schematically the worm embodiment of gate and
gate mover shown in FIGS. 7 and 8, from a side view, as viewed from
the chain side, such as in FIG. 2, but with many parts removed,
including the band rings and other gates;
[0057] FIG. 11 shows schematically a transmission component of the
invention for use mounted upon a rear wheel of a cycle;
[0058] FIG. 12A shows a view of a gate of another embodiment of the
present invention, from a side view, shown in the driving
position;
[0059] FIG. 12B shows a view of a gate of the embodiment of the
present invention shown in FIG. 12A, from a side view, shown in the
non-driving position;
[0060] FIG. 13A shows a gate of another embodiment of the present
invention, from a side view, with a different embodiment of a
detent;
[0061] FIG. 13B shows a top view of a gate of an embodiment of the
present invention, shown in FIG. 13A;
[0062] FIG. 14A shows schematically a gate of another embodiment of
the present invention, from a side view, which gate translates
against a spring under action of a solenoid, rather than rotating
around a hinge, with the gate in the driving position;
[0063] FIG. 14B shows schematically a gate of the embodiment shown
in FIG. 14A, after it has contacted the gate mover and is being
pushed against a spring to release it from the driving position;
and
[0064] FIG. 14C shows schematically a gate of the embodiment shown
in FIG. 14B, in the non-driving position.
DETAILED DESCRIPTION
[0065] A preferred general embodiment of the invention is shown
schematically with reference to FIGS. 2 and 3. FIG. 2 shows an
embodiment of the invention adapted to be used at the front chain
wheel of a bicycle, in place of a standard crank set. FIG. 2 shows
the transmission component 102 as viewed from the chain side (in a
conventional bicycle, the right side when driven forward). FIG. 3
shows schematically the transmission component 102 as viewed from
the non-chain side (the left side when driven forward). (In the
following discussion, conventional items are given the same
reference numerals as shown in FIG. 1 with respect to a
conventional bicycle and transmission. Also in the following, for
simplicity, it is assumed that the driving band is a conventional
bicycle chain. However, it can be other types of flexible driving
bands, and they are not excluded from the invention by the use here
of the term "chain." Further, for simplicity, it is assumed that
the cycle is a bicycle. However, it could be any wheeled device
that is driven by a band and wheel-type transmission, includes
tricycles and four wheeled cycles. These variations are discussed
in more detail after the basic discussion of the invention.)
[0066] A crank 11a, to which a pedal (not shown) is attached, is
coupled through a bracket 104 to an innermost band ring 112. The
band ring is innermost, as measured radially, with the origin being
the axle around which the crank 11a and the band ring 112 rotate.
The innermost band ring is mounted substantially conventionally
with bearings, to turn with the crank 11a, as the pedals turn. The
chain 14 is shown engaged by the innermost band ring 112. Band
engaging elements 108, in the form of roughly triangular teeth,
engage the chain between its links.
[0067] A support 150 is also coupled to the bracket 104 to rotate
with the crank 11a. The support 150 supports an outermost,
segmented, band ring 106, which is made up of a plurality of
individual ring components or gates 152. In this case, ten gates
152 are shown. Each gate 152 carries a plurality of band engaging
elements 158 like the innermost band ring, again in the form of
roughly triangular teeth. The outermost gates 152 are movable,
under control as discussed below, from a non-driving position (as
shown in FIG. 2) to a driving position, shown as discussed below.
Thus, the segmented band ring constitutes a variable configuration
ring assembly.
[0068] The driving position is better understood with reference to
FIGS. 4A-4E, which show schematically an edge view of a portion of
the innermost 112 and outermost 106 band rings, the support 150, as
well as the chain 14 (and an intermediate band ring discussed)
below). The view of FIG. 4A is from behind the chain ring, looking
forward. Only two links of the chain, are shown, one each at the
top and bottom of the chain ring, or, arriving and leaving it. As
shown in FIG. 4A, the outermost gates 152 are in the non-driving
position. They rest away from a driving plane, designated DP, in
which the innermost chain ring 112 permanently resides. The gates
152 can flip around a hinge 154, generally from left to right, as
shown in FIG. 4A, or out of the page, as shown in FIG. 2.
MOVING DRIVING BAND TO LARGER DIAMETER BAND RING
[0069] FIGS. 4B and 4C also show the outermost gates 152 in the
non-driving, or out of plane position. FIG. 4D shows one of the
outermost gates, 152a flipped to a driving position, so that the
band engaging elements 158 lie in the driving plane DP. FIG. 4E
shows both outermost gates 152a and 152b flipped to a driving
position. Thus, when all of the individual outermost gates 152 are
flipped to a driving position, and locked in place (as discussed
below) together, they constitute a band ring capable of carrying
the chain 14, but at a larger diameter than the innermost band ring
112. Thus, a change in gear ratio can be effected between that
arising from the large diameter outermost band ring 106 and the
small diameter innermost band ring 112.
[0070] A very important feature of the present invention is that
the gates 152 are arranged so that they move from a non-driving
position to a driving position when they are in a "free zone" as
defined below, rather than in the driving zone, forward of and
between the arrows D.sub.Z, as shown in FIGS. 1 and 2. The free
zone is as shown between the arrows F.sub.1 and F.sub.2, generally
to the rear of the band rings, in a circumferential location where
the chain does not engage any of the band rings. Thus, when motion
from the non-driving to driving position is made, the gate and
respective band engaging elements, or teeth, are under no load, and
not subject to any mechanical interference from the chain 14 (or,
more generally, any sort of power band). In general, the
circumferential size of the free zone for larger diameter band
rings is larger than the free zone for smaller diameter band
rings.
[0071] In operation, a gate in the free zone, such as the gate
designated 152f, is moved from the non-driving position to the
driving position while it is in the free zone, and this while it is
not contacting the chain 14. The motion from the non-driving
position to the driving position is under control of an actuator
that is discussed below. The gate 152f then moves into the driving
plane DB, in which plane the chain 14 also lies. As the gate 152f
then moves, in a clockwise direction as shown in FIG. 2 (generally
in the direction of arrow F.sub.2) under power from the rotation of
the cranks 11a and 11b, it encounters the chain 14, essentially
coming up from below the chain, and lifts the chain 14 off from its
engagement with the smaller, innermost chain ring 112. As each
successive gate 152 enters the free zone, it is moved by the
actuator (discussed below) into the driving position in the driving
plane DP and then encounters the chain 14. Eventually, the chain is
engaged entirely by gates 152 of the outermost chain ring 106, and
no longer contacts the innermost chain ring 112 at all. Thus, the
gear ratio is changed.
[0072] Two motions of the gate are described above:
circumferential, from out of the free zone, into the free zone, and
out of the free zone again; and perpendicular to the driving plane
DP, from out of the driving position to into the driving position
in the driving plane. These two motions are essentially
independent, except to the extent that the motion into and out of
the driving plane only occurs when the circumferential position of
a gate 152 is in the free zone. These two types of motion are
caused by two different sets of mechanical components.
[0073] In the embodiment shown in FIGS. 2 and 3 and 4A-4E, a
radially intermediate variable position band ring 162 is also
shown, with a plurality of intermediate gates 164, supported
hingedly from the support 150. Ten intermediate gates 164 are also
shown in FIG. 2.
[0074] The intermediate gates 164 function essentially the same as
do the outermost gates 152. An actuator moves them from an out of
driving position (shown in FIG. 4A for all three of the shown
intermediate gates, and in FIG. 4B for two of them) to a driving
position in the driving plane DP (shown with one in the driving
position in FIG. 4B, and all three in the driving position in FIG.
4C). Assuming that the chain is engaged by the innermost chain ring
112, if the intermediate gates 164 are moved into the driving
position when they are in the free zone, they pick up the chain 14
as they move around the circumference, in the same manner as is
described above for the outermost gates. Subsequently, the chain 14
may be removed from the intermediate band ring 162 by positioning
of the outermost gates 152 in the driving positions, as discussed
above.
MOVING DRIVING BAND TO SMALLER DIAMETER BAND RING
[0075] The forgoing has described, generally, moving the chain 14
from a smaller diameter band ring to a larger, by motion of the
larger gates from out of the driving position to into the driving
position. Reverse motion is also accomplished, moving the chain 14
from a larger diameter band ring to a smaller.
[0076] Consider if the chain 14 is carried by the radially
outermost band ring 152. Thus, all of the outermost gates 154 are
in the driving position in the driving plane DP, as are all of the
intermediate gates 164. The innermost band ring 112 is also in the
driving position, in the driving plane, as it is permanently in the
driving plane DP.
[0077] When it is desired to move the chain 14 from the larger
diameter, outermost chain ring 106, a first outermost gate 152,
when and only when it is in the free zone, rearwardly between the
arrows F.sub.1 and F.sub.2 as shown in FIGS. 2 and 3, is moved from
the driving plane, to out of the driving plane DP. All of the
following outermost gates 152 are also subsequently so moved. Thus,
the chain 14 gets picked up by the gates 164 in the intermediate
chain ring 162, which are all in the driving plane DP, at a
radially smaller circumference.
[0078] Similarly, when it is desired to move the chain 14 from the
relatively larger diameter, intermediate chain ring 162, to the
smallest diameter, innermost chain ring 112, a first intermediate
gate 164, when and only when it is in the free zone, is moved from
the driving plane DP to out of the driving plane, as are all
following intermediate gates 164. Thus, the chain 14 gets picked up
by the chain engaging elements 108 of the innermost chain ring 112,
which are all permanently in the driving plane DP, at a radially
smaller circumference.
ACTUATING THE GATES
[0079] The gates can be moved from a non-driving position to a
driving position and vice-versa by various mechanisms. A preferred
mechanism is shown with reference to FIGS. 3, 5A-5B and 6A-6C.
[0080] FIG. 3 shows the transmission component 102 from the rider's
left side of the cycle, or the non-chain side as a rider would ride
the cycle. Several of the outermost gates 152 are shown, and only
one of the intermediate gates 164 are shown. However, it will be
understood that in actuality, there are a plurality of intermediate
gates 164 also.
[0081] An actuator set 170 is supported by an actuator support 172
that is clamped to the chain stay 174. The actuator support
supports two actuator units: one 176, which actuates the outermost
gates 152; and another 178 for the intermediate gates 164. The
actuator units 176 and 178 are essentially identical, but for the
lengths and shapes of some of the links. The actuator unit 176 for
the outermost gates will be described as representative of
both.
[0082] Each actuator unit includes an actuator 180, such as a
simple DC motor. Other types of actuators are possible, and are
described below. The motor axle 182 carries a cam 184 and the cam
184 carries a link 186. The link 186 is mounted eccentrically on
the cam, relative to the axle 182. The link 186 is connected to a
combination gate mover arm 188. When any particular gate passes by
the circumferential position at which the gate mover arm is
located, the gate may be actuated by the respective actuator unit,
e.g. 176.
[0083] In the embodiment shown, the actuator 180 is driven to its
extreme in one or the other rotary direction, where it stops. This
drives the axle, cam, link and gate mover to a configuration, where
the entire mechanism either causes placing the gate 152 into a
driving position, or picking it from a driving position, as
explained in more detail below, in connection with FIGS. 5A-D and
6A-C.
[0084] FIGS. 5A-D show a single cam 184, link 186, gate mover 188
and gate 152, from below (i.e., from the ground, if the cycle were
in the driving position), as if the bottom of FIG. 3 were tipped
toward from the observer. FIG. 5A shows a gate as it is about to be
moved from a non-driving position to a driving position. FIG. 5B
shows the gate just after it has moved to the driving position. In
both FIGS. 5A and 5B, the cam, link and gate mover are in the
placing configuration, with the placer trigger portion 190 of the
gate mover contacting the gate 152, and with a cam surface of the
cam 184 stopped against a placing stop 195. The axle 182 about
which the cam rotates, and the picking cam stop 197 are shown in
phantom in FIGS. 5A and 5B. The gate rotates around the axle 154,
which is supported by the support 150.
[0085] FIG. 5C shows a gate as it is about to be moved from a
driving position to a non-driving position. FIG. 5D shows the gate
just after it has moved to the non-driving position. In both FIGS.
5C and 5D, the cam 184, link 186 and gate mover 188 are in the
picking configuration, with the picker trigger portion 192 of the
gate mover 188 contacting the gate 152, and with a cam surface of
the cam 184 stopped against a picking stop 197.
GATE CONFIGURATION
[0086] A typical configuration for a gate 152 is shown with
reference to FIGS. 6A-6C. FIG. 6A shows a gate 152 from the side,
as depicted in FIGS. 5A-5D. FIG. 6B shows a gate from the top, or,
from the non-chain side, for instance as seen in FIG. 3. FIG. 6C
shows the gate from an end view, looking down directly onto chain
engaging elements, or teeth 158. FIG. 6C might be thought of as a
view from the chain itself. Each gate 152 is composed of band
engaging elements 158, which rotate around the hinge 154, which is
mounted in the support 150. Typically, a plurality, such as three
band engaging elements are provided per gate. However, as few as
one is possible.
[0087] The gate has an angled surface 194, which has a placer
region 196 at one end and a picker region 198 at the other. The
surface 194 is shown to be pyramidal, but it need not be. It can be
a simple slant, or curved. It is basically a ramp cam surface,
which is pushed away by the gate mover as the ramp passes by the
gate mover in the ramp's circuit around with the pedals. However,
it is beneficial for it to be slanted on both faces, as shown in
FIG. 6C, because then, if the operator rotates the pedals
backwards, which is common with certain types of transmissions,
then the transmission will not jam, but will simply be passed over
in the same manner as if the pedals were moving in a forward
direction.
[0088] As shown in FIG. 5A, when the gate mover 188 is in the
placing configuration, the placer trigger portion 190 of the gate
mover 188 is located so that it contacts the placer region 196 of
the gate on one side of the hinge 154. As the gate rotates around
the circuit with the pedals, out of the page as shown in FIG. 5A,
the gate encounters the stationary gate mover. The gate mover
pushes against the slanted surface of the gate, which then flips
away to its other position. The gate tilts from a non-driving
position to a driving position (as shown in FIG. 5B). The gate is
spring loaded, as discussed below, so that it moves slightly beyond
the position where it contacts the gate mover 188 after it has
moved into the driving position, so that on subsequent passes the
gate mover 188 does not rub against the gate. It is important that
there be enough of a lever arm L.sub.1 between the hinge and the
placer end 196 of the gate, so that the gate will move into the
driving position when the placer trigger encounters the gate. It
has been found that as little as 0.375 in. (0.95 cm.) is
sufficient.
[0089] As shown in FIG. 5C, when the gate mover 188 is in the
picking configuration, the picker trigger 192 of the gate mover 188
is located so that it contacts the picker region 198 of the gate on
the other side of the hinge 154, so that the gate tilts from a
driving position (as shown in FIG. 5C) to a non-driving position,
as shown in FIG. 5D. Again because the gate 152 is spring loaded,
it moves slightly beyond the position where it contacts the gate
mover 188 after it has moved into the non-driving position, so that
on subsequent passes the gate mover 188 does not rub against the
gate. It is also important that there be enough of a lever arm
L.sub.2 between the hinge and the picker end 198 of the gate, so
that the gate will move out of the driving position when the picker
trigger encounters the gate.
[0090] The spring loading may be of various configurations. A
preferred embodiment has a pair of biasing springs 200, which force
between the axle of the hinge 154 and a floating pin 202, which
carries a cam 204. The cam 204 is pressed against a reference edge
206. As the gate moves from, for instance, the non-driving position
to the driving position, the cam 204 encounters the reference edge
and rolls around it, thereby stretching the biasing springs 200. As
soon as the cam passes the extreme of the edge, it is pulled by the
biasing spring back toward the hinge 154, and gently locks the gate
in the driving position. Thus, the springs 200, reference edge 206
and cam 204 act as a detent. Other schemes for gate motion are
possible. Various types of springs (leaf, coil, etc.) and detents
(cams, spring-loaded balls, etc.) may be used. These components
serve to quickly move the gate into the target position once it has
been actuated, and to retain it there until actuated to the
opposite configuration. Such an alternative embodiment for a gate
is shown with reference to FIGS. 12A and 12B, and 13A and 13B,
discussed below.
[0091] It is also important to minimize friction between the angled
surface 194 and the picking and placing triggers of the gate mover
188. Abrasion resistant, low friction materials can be used.
Alternatively, each of the picking and placing triggers 192, 190,
can be free, rotating disks mounted to spin freely on an axle S,
such as shown in FIG. 5A.
ACTUATOR CONTROL
[0092] In the embodiment discussed above, the actuators 180 are DC
motors. For instance 1.5 volt, DC motors with copper wipers are
suitable. A suitable control system works by providing current to
drive the motor in a first direction, until the actuator cam 184
hits a first stop, for instance the placing stop 195. The motor is
sized such that it simply stops when the cam hits the stop, and
does not overheat, even though power is still applied to it.
Similarly, when it is driven to the opposite extreme and the
actuator cam 184 stops against the picking stop 197, the motor
again simply stops.
[0093] A suitable control apparatus is shown with reference to FIG.
3. A speed sensor 210 is mounted on the chain stay 174, facing the
rear wheel. A rotation marker 212 is mounted on the cycle wheel 26,
for instance on a spoke, facing the speed sensor 210. Each rotation
of the wheel causes an electric signal to be generated at the
sensor 210. A typical such speed sensor uses a Hall effect magnetic
sensor, but many other types are known. This speed signal is
transmitted to a power and control module 214, for instance by
wires 216. Alternatively, the connection can be wireless, in the
same manner as are now many bicycle speed monitors. The control
module 214 is also connected, for instance by wires 218 to the
actuators 180, to supply power thereto at controlled times and
durations and directions, i.e. positive or negative current.
[0094] In a typical arrangement, the actuator 180 that actuates the
outermost gates 152, on the largest diameter band ring 106, is
controlled to place the gates into the driving position only after
the rotational speed of the bicycle wheel 26 exceeds an "outermost
band ring up-shift speed." If such a speed has been reached, then
the wheel 26 is turning so fast that the operator could benefit
from an upshift to the outermost band ring, and the system delivers
an upshift. The gates remain in the driving position, until the
speed of the wheel 26 drops below another speed, designated the
"outermost band ring down-shift speed." At that point, it has
become difficult for the operator to maintain the desired pedal
rotation rate with the higher transmission ratio effected by
running the chain on the largest band ring. The system shifts to a
lower gear ratio, by signaling the actuator 180 to rotate the
opposite direction, thereby picking the gates from the driving to
the non-driving position, thereby allowing the chain to drop down
from the outermost band ring to a smaller diameter band ring, as
discussed above. For instance, if there is only one variable
conformation band ring, and one permanent fixed band ring, then the
chain drops down to the fixed, innermost band ring 112. If there is
an intermediate band ring, such as 162 shown in FIG. 2, then the
chain drops down to that intermediate band ring.
[0095] The power and control unit 214 includes a data processor and
signal generator such as the microprocessors that are typical in
cycle computers that act as speedometers, odometers, cadence
monitors, etc. The data processor is capable of comparing the
present speed of the cycle, based on the rotational speed of the
wheel, and other factors with user or factory set up-shift and
down-shift velocities. Based on the comparison, the appropriate
actuator is actuated in the appropriate direction. It typically
features a display 300 and input elements 302, such as buttons.
[0096] Typically, there is hysteresis in the system, to avoid
chattering. In other words, for any given band ring, the upshift
velocity for shifting up to the band ring from a smaller band ring
is slightly, but noticeably, greater than the corresponding
down-shift velocity for shifting down from it. Otherwise, for
instance if the two velocities were equal, if the wheel achieved
the up-shift velocity and then immediately dropped below the
up-shift velocity just after it had been achieved, the system would
try to down-shift almost immediately after up-shifting, resulting
in chattering back and forth between up and down shifting. The same
would be true upon down-shifting. In general, a difference that
corresponds to one mile an hour has been found to be suitable,
although different users may find that more or less hysteresis is
more suitable for them. Thus, these velocities can be user
programmed according to known means, using the display 300 and
buttons 302 to control the controller. Further, the measure of
hysteresis can be based on the speed of the cycle, or the cadence
of the pedals, or a combination of both. If the hysteresis is based
in any part on the pedal cadence, then the processor must take into
account the fact that upon shifting, an abrupt change in pedal
cadence arises.
[0097] For convention, as used herein, the up and down-shift
velocities are designated based on the actuator involved. For
instance, the outermost up-shift velocity is for shifting from an
intermediate to an outermost band ring. The outermost down-shift
velocity is for shifting from the outermost band ring to a smaller
band ring. If there is an intermediate band ring, the intermediate
up-shift velocity is for shifting from a smaller, inner band ring,
up to the larger intermediate ring. The intermediate down-shift
velocity is for shifting from the intermediate band ring down to a
smaller, inner band ring.
GOALS ACHIEVED
[0098] Thus, the described invention accomplishes the goals set
out. It provides an automatic shifting transmission, which the user
need not worry about. The shifting occurs at appropriate times.
Most importantly, the mechanical components move in the free zone
when they are not under mechanical load, and thus stripping and
missing of gears is totally eliminated. This free zone shifting
occurs for both up-shifting and down-shifting. The device can be
easily retrofitted on virtually all existing conventional bicycles.
All that must be done is the conventional chain ring and perhaps
pedal assembly must be switched for the band ring assembly
discussed. The actuator support plate and associated actuators must
be provided, along with a wheel speed sensor and a power and
control unit.
VARIATIONS
[0099] Many variations on the above described invention can be had
without departing from the spirit of the invention.
GATE DESIGNS
[0100] An alternative preferred embodiment of a gate is shown with
reference to FIGS. 12A and 12B. FIG. 12A shows another embodiment
of a gate of the invention, oriented in the driving position. FIG.
12B shows this embodiment oriented in the non-driving position. The
gate 552 is hinged through a hinge 554 to the support 150, as
discussed above. The primary difference is the spring and detent
mechanism. The body of the gate 552 is partially hollow, in which
recess resides a coil spring 500, which is loaded against a stop by
a ball 504. The ball moves around an edge of a guide 506, which
acts as a sort of cam follower. In this embodiment, the guide 506
plays the role of the edge 206 of the embodiment shown in FIG. 6B.
The ball 504 functions as does the roller cam 204, and the coil
spring 500 functions analogously to the springs 200 shown in FIG.
6A.
[0101] If the gate is in the driving position, as shown in FIG.
12A, and the gate moves along with the support 150, so that it
encounters a gate mover, with the gate mover positioned to press
upon the picker end 598 of the gate, it will push the gate such
that it rotates counter clockwise around the hinge 554 (as shown in
FIG. 12A). The ball 504 will be forced, by the guide 506 against
the spring, compressing the spring 500, so that there is clearance
for the ball 504 to move around the edge of the guide 506, and then
roll back away from the spring 500, so that the guide 506 again
prevents the ball from moving. With the ball gently locked in
place, the gate 552 will stay in the nondriving position.
[0102] In contrast, if the gate is in the non-driving position, as
shown in FIG. 12B, and the gate moves along with the support 150,
so that it encounters a gate mover, with the gate mover positioned
to press upon the placer end 596 of the gate, it will push the gate
such that it rotates clockwise around the hinge 554 (as shown in
FIG. 12B). The ball 504 will be forced, by the guide 506 against
the spring, compressing the spring 500, so that there is clearance
for the ball 504 to move around the edge of the guide 506, and then
move back away from the spring 500, so that the guide 506 again
prevents the ball from moving. With the ball gently locked in
place, the gate 552 will stay in the driving position.
[0103] A potential drawback of this embodiment is that in many
cases, the ball moves around the guide with significant friction
therebetween, thereby causing wear, and increasing the required
actuation force. The embodiment shown in FIG. 6A, in contrast, has
much less friction, because the roller 204 spins on the axle 202
and rolls around the edge 206.
[0104] Another embodiment of a detent of the invention is shown
with reference to FIGS. 13A and 13B, which are analogous to FIGS.
6A and 6B. In this embodiment, the spring action is provided by a
leaf spring 600, which is at the end of the gate 652 distant from
the engaging elements 658. The leaf spring 600 is anchored to the
body of the gate at a base end 605 or by some other suitable means.
A yoke portion 670 of the leaf spring 600 engages an axle 655,
which, as in the embodiment shown in FIG. 6A, carries upon it a
roller 604. The roller 604 is forced away from the leaf spring 670
by the spring action, into the edge 606. As with the embodiment
shown in FIG. 6A, as the gate 652 is tipped around its axle 654,
the edge 606 forces the roller 604 back against the spring 600
force, resulting in the roller 604 rolling around the edge 606, and
then popping into place on the other face of the edge 606, under
action of the spring reaction force. Thus, it is similar to that
shown in FIG. 6A, except that rather than the spring 200 pulling
the roller 204 toward the edge 206, the leaf spring 600 pushes the
roller 604 toward the edge 606. Thus, the location of the spring,
roller and edge are partially reversed.
[0105] Still another embodiment of a detent mechanism is shown with
reference to FIGS. 15A-15C. This embodiment uses a roller and knife
edge, such as is used in the embodiment shown in FIGS. 6A-6C and
internal springs 800 that are compressed, such as is shown in FIGS.
12A and 12B. The springs 800 push against an axle 802 that carries
a wheel 804, which rolls around a reference edge 806, as discussed
above. The springs 800 are retained within the body 853 of a gate
852, in channels 851. Thus, the springs 800 are protected against
the elements. Furthermore, the wheel 804 rolls around the reference
edge 806 without much, if any friction. As shown in phantom in FIG.
15C, the band engaging elements 858 may be on the spring side of
the detent mechanism. Alternatively, the band engaging elements can
extend in the opposite direction (not shown), from the opposite end
of the gate, near the reference edge. In either case, the hinge
around which the gate tips must be properly located, as shown in
FIG. 5A, or 12A. Another alternative is to arrange such a detent
mechanism with the springs in tension, rather than in compression.
Many such variations are evident to the person skilled in the
art.
WORM AND GEAR ACTUATION MECHANISM
[0106] As another variation, a different actuation mechanism can be
used. An alternate is shown with reference to FIGS. 7 and 8, which
correspond roughly to FIGS. 5A and 5C. FIG. 7 shows a worm and worm
gear actuator assembly, from below, in the same manner as FIG. 5A
shows the assembly also shown in FIG. 3.
[0107] The gate 152, placing trigger 190 and picking trigger 192 of
the gate mover 188 and gate support 150 are all identical to that
discussed above. The actuator assembly support plate 272 is shown
in phantom in FIG. 7, and is placed correspondingly to the support
172 shown in FIG. 3. The elements mentioned immediately above are
positioned below the support plate 272 when the cycle is in the
driving orientation. The following elements are located on the
other side, above the support plate 272. A worm gear 274 is
rotatable about an axle 284, and is rigidly coupled to the gate
mover 188 such that they both rotate around the axle 284 together.
The worm gear 274 engages and is driven by a worm 276 that is in
turn driven by a motor 280.
[0108] Thus, rotation of the motor in one direction causes rotation
of the worm 276 and its worm gear 274, and the worm gear axle 284,
thereby swinging the gate mover 188 around the worm gear axle, so
that it engages the gate 152 at the picker 198 and placer 196
surfaces as desired. FIG. 7 shows the configuration where the gate
152 is about to be placed into the driving position and FIG. 8
shows the configuration where the gate is about to be picked from
the driving position. Using a worm and worm gear may provide for a
more compact, robust mechanism.
[0109] For instance, a suitable arrangement includes a worm with
3/8 in. (0.95 cm) diameter and a worm gear with a 0.75 in. (1.9 cm)
diameter.
[0110] In some cases, the worm embodiment may suffer from jamming,
and care must be taken to avoid this. For instance, the motor may
drive the worm with such momentum toward one extreme, that when
time comes to reverse the motion, the motor is locked due to a
jamming of the mechanism. Such jamming may arise due to flexibility
of the shafts upon which the various elements turn, as well as play
in the gears themselves. One way to minimize the risk of jamming is
to monitor the location of the motor shaft, such as with an angular
encoder, and to send this location to the controller. The
controller can then be programmed to stop the worm just short of
full travel into the mechanical stop. Or, alternatively, the
mechanical stop can be eliminated altogether.
[0111] Another variation may have the motor of one actuator unit
above the support plate 172, and the motor of the other below, with
the associated respective links on the opposite face of the plate
from their motor. This arrangement may also be more compact,
depending on the size and shape of the cycle frame to which it is
attached.
SERVO MOTORS
[0112] Rather than using a simple DC motor, it is also possible to
use servo motors, such as the type that are used in flying model
airplanes. A potential drawback with some such servo motors is
their weight, and also the fact that they continually draw power
when actuated, even when not moving. Thus, upon placing or picking
the gate, if left in the placing or picking configuration, the
servo motor will draw power, thereby draining the battery. In
general, servo motors sold by Futaba Corporation of Azabu Jyuban
Minato-ku Japan, under model number S3101 have been found to be
suitable. Other schemes may have linkages that allow a motor to be
rotated in only one direction, rather than needing to reverse
directions.
DIFFERENT MOTIONS FOR GATE
[0113] The gates discussed above are arranged to rotate, around a
hinge, into and out of the driving position. Motion is effected by
the placer trigger 190, pressing on the placer 196, or the picker
trigger 192 pressing on the picker 198. However, as shown in FIGS.
14A - 14C, it is also possible for a different arrangement, where a
gate mover 788 contacts a gate 752 at the same spot for both
picking and placing. For instance, rather than rotating into place,
the gate 752 can translate perpendicularly to the driving plane DP,
against a spring 700 with a catch (not shown) that holds the gate
752 in the driving position (conceptually similar to the type of
mechanism in a simple push-button, retractable ball point pen, but
robust enough to withstand the forces of chain motion). As shown in
FIG. 14B, a subsequent push of the gate 752 into the spring 700
releases the catch, and the gate 750 translates back out of the
driving plane, perpendicularly to the driving plane, to the
position shown in FIG. 14C.
[0114] In such a case, rather than having a separate placer trigger
and picker trigger, the gate mover 788 may have or constitute a
single combined trigger 790, which merely presses against the gate
in the same spot, rather than in a picking location and a placing
location. Such an embodiment can be effectuated with a servo
mechanism or a solenoid type actuator 780, the core 781 of which
moves linearly. This embodiment has fewer moving parts, which is an
advantage. One potential drawback of such an embodiment is that the
throw of the actuator may need to be greater than in the rotating
case. However, the maximum throw of the gate is typically less,
because the gate motion is purely perpendicular to (i.e., directly
toward) the driving plane, whereas in the rotational case, the gate
motion has a perpendicular component and a parallel component.
[0115] For instance FIG. 14A shows a linearly translating
embodiment of the invention with the gate 72 in the driving
position, about to be removed from the driving position. A roller
783 is free to spin on an axle 785 and moves with a frame 787 that
is coupled to the solenoid core 781. The core and the frame and
roller translate in a straight line normal to the driving plane. To
remove the gate from the driving position, the solenoid 780 is
energized to advance slightly, to the position shown in FIG. 14A,
so that when the band ring rotates past it, the roller 783
encounters the angled ramp 797 of the gate, forcing the gate
slightly toward the driving plane, against the spring 700, to the
position shown in FIG. 14B. This releases a detent catch. The catch
releases, and the gate 752 moves away from the driving plane, along
guide channel 754, pushing the wheel 785 and solenoid elements back
to a withdrawn configuration as shown in FIG. 14C. When it is
desired to place the gate 754, the solenoid is energized and moved
toward the driving plane to a placing position. When in this
placing position, the gate mover wheel pushes the gate down against
the spring 700, into the catch, where it stays, thus, engaging the
driving band.
[0116] It is also possible for the motion of the movable
transmission component to be within a driving plane, rather than
perpendicular to it. For instance, there are known automatic
transmissions for bicycles that have movable components that move
radially, simultaneously with each other, thereby changing the
effective radius of the chain wheel, either front or rear. See, for
instance, U.S. Pat. Nos. 4,878,883 Wheless, 4,642,070 to Walker,
5,407,395, to Kramer, 5,582,555 to Miller, 5,772,546, to Warszewski
and 4,454,766 to Mills, which are all incorporated herein fully by
reference. In all, while there are in some cases components that do
move to a driving configuration while they are in the free zone,
there are always, at the same time, components that are in the
driving zone that are also moving to the driving configuration.
Thus, those components are engaging the driving band while also
being urged to change to a different driving configuration. This
entails complications of grinding, alignment, missing. They also
require relatively large forces to be applied to moving the
components, because they are simultaneously moving the driving band
to another configuration, for instance a larger diameter around the
chain wheel, while moving the transmission component.
[0117] It is possible to apply one general principal of the
invention, to most of these prior art concepts, by configuring the
actuation of the movable components so that they move only in the
free zone, and not in the driving zone. Typically this would also
entail decoupling the plurality of movable components from each
other so that they do not move to the driving configuration
simultaneously, as is common. Thus, the shifting actuator would act
only on the movable component that is in the free zone.
REAR WHEEL
[0118] The invention can also be applied to a rear wheel sprocket
cassette 418. The basic operation of a rear wheel implementation of
the transmission component 402 is the same as a front chain wheel
implementation. The sprocket 418 is composed of a plurality of gear
wheels, of which the innermost 412 is a fixed conformation with no
moving gates. The chain 14 is shown engaged by the innermost gear
wheel 412. A bracket 404 connects this gear wheel to the bicycle
rear wheel 26, which is shown only fragmentarily, along with some
of its spokes. The bicycle wheel rotates as indicated by the arrow
V when the cycle moves in a forward direction. A support 450
connects the innermost gear wheel 412 to an outermost gear wheel
406 that is segmented with gates 452, in the same manner as the
outermost front chain ring 152 discussed above. An intermediate
gear wheel 462 is also shown, which is segmented with gates 464.
Such an intermediate gear wheel is optional, as is a front
intermediate chain ring 162, as discussed above.
[0119] For operation of the rear wheel embodiment, the driving zone
is rearward of the gears, generally between the arrows D.sub.Z,
which point generally toward each other. The free zone is generally
forward of the gears, generally between the arrows F.sub.1 and
F.sub.2, which point generally toward each other.
[0120] An actuator unit is provided as for the front chain ring
embodiment, typically mounted adjacent the gear cassette, and
generally forward of it, on the chain stay 174 or the seat stay
175, or both, as is convenient, depending on the locations of the
stays, the amount of space therebetween, the size of the
components, etc. As miniaturization trends continue to reduce the
size of electronic components, more possibilities for locating the
actuator unit will arise and be evident to those skilled in the
art.
[0121] A rear wheel transmission component of the invention can be
used alone, or, in combination with a similar front wheel
transmission component of the invention. Furthermore, if either is
used alone, it can be paired with a conventional derailleur on the
other wheel, if desired, to either increase the spread of the gear
ratios, or the number of gear ratios within a spread. Or both.
[0122] Because smaller rear gear wheels result in a higher gear,
while a smaller front chain rings result in a lower gear, the
considerations of up-shifting and down-shifting discussed above in
connection with a front, chain ring embodiment, are reversed.
MECHANICAL GOVERNOR
[0123] Another variation is to use a mechanical governor, rather
than an electronic one to measure the wheel speed and actuate the
gates. For instance, a fly-ball type scissors mechanism can be
arranged between the interlaced spokes of a rear wheel, which
mechanism expands its diameter as the rotational velocity of the
rear wheel increases, and contracts its diameter as the rotational
velocity decreases. The changing effective diameter of the
mechanism can be used to trip sensors that energize, or effectuate
actuator motion. Typically, however, it has been found that
mechanical governors are more complicated than are electronic
controls, as discussed above.
SHIFT BASED ON PEDAL ROTATION
[0124] The embodiment discussed above uses the rotational speed of
the rear wheel to determine when to shift. It is also possible to
use the rotational speed of the pedals, by mounting a similar
rotation marker 213 on the crank 11b, as shown in phantom in FIG.
3, with a speed sensor 211 mounted on the seat tube 177. In such an
embodiment, care must be taken to accommodate times when the
cyclist slows down or stops pedaling altogether, and simply coasts,
as this can occur at both very fast and very slow speeds. It may be
beneficial to monitor both the pedal speed and the wheel speed, and
to make shifts based on a combination of the two.
OTHER TYPES OF CYCLES
[0125] Of course, a preferred use for the present invention is for
bicycles. The invention can be supplied with new bicycles, and can
easily be retrofitted to existing bicycles, simply by providing a
segmented chain ring or rear gear cassette, along with an actuator
set and control unit. There are also in use a large number of adult
tricycles, used either by people who never learned how to ride a
bicycle, or, for some reason are unable or prefer not to use a two
wheeled cycle. The invention is applicable to such cycles, with
suitable modification to be mounted on the somewhat differently
configured frame elements. Similarly, four wheeled cycles exist,
and can make use of the invention.
OTHER TYPES OF TRANSMISSION BANDS
[0126] Most known cycles use a linked metal roller chain for
transmission, along with mating toothed gear wheels. It is also
possible to use many different types of transmission bands, such as
v-belts, flat and o-ring belt systems, timing belts, posidrive type
belts, with a metal or synthetic fiber core, coated with a plastic,
such as polyurethane, such as sold by SDP Stock Drive Products, of
New Hyde Park, N.Y., ladder chains, synchromesh cable drives,
beaded chains, etc. In general, the invention can be used with such
systems. What is required is that the gates be shaped to engage the
band when the gate is in the driving position, and also the gate
must be such that it can be swung into position while in the free
zone, without interfering with the band.
[0127] The foregoing discussion should be understood as
illustrative and should not be considered to be limiting in any
sense. While this invention has been particularly shown and
described with references to preferred embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
spirit and scope of the invention as defined by the claims.
[0128] Many intermediate generalization combinations of the
elements of the invention shown are possible, and are contemplated
as part of the invention herein. For instance, the transmission
element can be used on either the front, or the rear, or both. In
either of these cases, the transmission band can be any of the
types discussed. One or more than one variable configuration band
ring or wheel can be used. The cam and linkage, or worm and worm
gear embodiments can be used with any of the other described
embodiments, front or rear position, etc. All of the foregoing
combinations and variations can be used with two and three and four
wheeled cycles. Furthermore, the applicants contemplate the
invention to include not only a transmission for a cycle, such as
may be retrofitted on existing bicycles and other cycles, but also
an entire, automatic transmission bicycle, with a transmission that
embodies the features and characteristics of the emobidiments of
transmissions disclosed herein.
[0129] The corresponding structures, materials, acts and
equivalents of all means or step plus function elements in the
claims below are intended to include any structure, material, or
acts for performing the functions in combination with other claimed
elements as specifically claimed.
* * * * *