Note: Descriptions are shown in the official language in which they were submitted.
to
PROPULSION AND SPEED CHANGE MECHANISM
- FOR LEVER PROPELLED BICYCLES
FIELD OF THE INVENTION
This invention relates to propulsion and speed
change mechanism for lever propelled bicycles.
The invention is especially suitable for use in
a bicycle which is propelled by transmitting force imparted
from the up and downward motion of propulsion levers to the
rear wheel through a chain and chain gears (also known as
sprockets) in which speed change is achieved by changing
the position of connecting bars which connect the chain with
speed change arms. It will be appreciated that the term
bicycle comprehends other vehicles which are adapted -to be
propelled in a similar manner and which have different number
of wheels, such as tricycles.
BACKGROUND OF THE INVENTION
Conventional bicycles are mostly driven by circular
motion of crank pedals. However, only a small portion of the
360 rotation of the crank is used to propel the bicycle and
the rest of the rotary motion is wasted. Therefore, the
operator spends more energy and feels tired more readily
for the same running conditions. Since the pedal stroke
cannot be adjusted and a full turn is inevitably required
to drive the conventional bicycle, the rider is not comfortable
if his or her physical condition does not fit with the crank
pedals circular motion stroke. Furthermore speed change in
a conventional bicycle involves the use o-f various size
chains gears mounted in the same axle which is a complex and
heavy structure, demanding higher motion energy. Oftentimes
it is necessary to stop and reconnect the chain, since it
can be disconnected from the speed change gears while in
operation.
Although lever propelled bicycles, propelled by up
and downward motion of propulsion levers have been proposed,
the mechanisms used for transmitting the motion energy of
the propulsion levers to the rear wheel has not been satisfact-
or. Often a fan-type gear or a rack gear is connected to
the propulsion levers and engaged with a pinion which is mounted
on the rotary axle of the rear wheel. The bicycle is prop-
oiled by repeated forward or backward or up and downward
motion of the rack gear or fan-type gear. When the motion
is stopped at the top-most and bottom-most position of the
propulsion levers, the momentum of the rack or fan gear is
transmitted as a shock to the pinion on the rear wheel.
Thus, the propulsion is accompanied by repeated, unreasonable
shocks and is prone to unreliability . Especially, the latch
and paw of a free wheel in the propulsion mechanism are
readily worn out and may break due to the severe repetition
of shocking contact and separation. In addition speed change
has been achieved by changing the length of a speed change
bar. The connecting pin of a connecting bar of the fan-
type gear or rack gear which moves the rear wheel is fitted
into one of the notches in a row of notches on the speed
change bar which is moved up and down on the bar by a speed
change wire actuated by pushing a speed change wire actuated
by pushing a speed control lever up and down. The connect- -
in pin, however, is subject to a substantial burden while
in operation which is exacerbated during the pulling motion
of the speed control lever. Under this heavy burden, it is
very difficult to move the connecting pin by manipulating
-the small speed control lever by hand. The operator may
then have to s-top before making a speed change, and speed
change while the bicycle is in motion is difficult. The
foregoing problems have militated against the practical use
of lever propelled bicycles, even though the energy
required to propel such a bicycle is much less as compared
with conventional bicycles propelled by circular motion of
crank pedals.
SUMMARY OF THE INVENTION
It is the object of this invention to provide
an improved propulsion mechanism as well as an improved
speed change mechanism for lever propelled bicycles thereby
to increase the usefulness of such bicycles.
In accordance with an embodiment of this invention,
two one-way clutches (roller-type free wheels) attached with
chain gears are mounted at both ends of the axle of the rear
wheel of the bicycle. A chain is entrained around the chain
gears. When a pair of chains is used one of the ends of
the chain is connected, preferably with a see-saw cable
which is supported around a guide roller. The other end of
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the chains is connected, preferably with connecting bars
having connecting pins, to the speed change arms of a
propulsion lever arm assembly. The speed change arms and
the propulsion levers are a one piece assembly pivotal
mounted for oscillating motion. Each speed change arm
is equipped with pivotal members, which may be triangular
pieces pivotal fixed thereto These pivotal members hold
the connecting pin of the connecting bar. A control bar,
which may have cam projections, can be adjusted by a speed
control, and pivots any one of the pivotal members selectively
outward of the speed change arm. The connecting pin of the
connecting bar from the chain is held by the pivotal member
which extends from the speed change arm. Up and downward
(oscillatory) movement of the propulsion levers causes
the chain to make a see-saw motion. The rear wheel is thus
moved forward by the chain gear. Upon adjusting the speed
control, any one of the pivotal members of the speed change
arm is extended by the control bar from the speed change
arm and the connecting pin is automatically caught in a
notch on the extended pivotal member. The connection prom
the chain is therefore made to different positions on the
speed change arm. Thus, speed change is obtained readily
and even while the bicycle is in operation. At the same
time, the flexibility of the chain reduces shock caused
by momentum when the up and downward motion of the propulsion
levers is stopped at the top-most and bottoms position
thereof. This also avoids unreasonable shocks to the propel-
soon devices (the clutches and other mechanisms in the rear
(
wheel). Thus, these devices are less likely to fail and
wear out. In as much as the bicycle is propelled by the
propulsion levers, motion energy of the legs is not wasted
and the up and downward motion of the propulsion levers
is used sully to propel the bicycle. A feature of the
invention is to provide a bicycle which an operator can
ride more comfortably and easily for a longer time, as
compared with a conventional bicycle.
Accordingly, the present invention provides a
propulsion mechanism for a lever propelled bicycle having
a frame with a main shaft portion and a rear shaft portion
disposed rearwardly of said main shaft portion on said frame,
said mechanism comprising a pair of propulsion levers for
receiving pedals, a pair of arms, a journal, said journal,
said levers and said arms being a one piece assembly with
one of said pair of levers and one o-f said pairs of arms
spaced from the other said pair of arms, said one piece
assembly being pivotal mounted on said main shaft portion,
a rear axle attached to said rear shaft portion, a rear
wheel hub journal Ed on said rear axle, a pair of chain gears
spaced from each other and journal Ed on said rear axle, a
pair of one-way clutches connecting said chain gears to
said hub, a chain entrained on said chain gears, and means
connecting said chain to said arms to execute see-saw motion
as said levers and arms are oscillated upwardly and down-
warmly by force supplied to said pedals.
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In a narrower aspect of the present invention,
the chain has two parts, one entrained on one of said chain
gears and the other on the other of said chain gears, each
of said chain parts having opposite ends, one of said chain
parts being connected to one of said arms, one of said
ends of the other of said chain parts being connected to
the other of said arms, a cable connecting the other of
said opposite ends of said chain parts, and roller means
rotatable mounted on said frame for guiding said cable.
By a variant, said one-way clutches include
a pair ox free-wheel means being rotatable mounted on said
rear axle adjacent to said opposite ends of said rear axle
and being releasable engagable with said hub and different
ones of said chain gears.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, features and
advantages of the invention as well as a presently preferred
embodiment thereof will become more apparent from a
reading of the following description in connection with the
accompanying drawings in which:
FIG. 1 is a general elevation Al view of a bicycle
equipped in accordance with this invention;
FIG. 2 is a perspective view showing the propulsion
and speed change mechanism which is an essential part of
the bicycle shown in FIG. 1 and is provided in accordance
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with this invention;
FIG. 3 is an exploded view of -the hub and one-way
clutch mechanism which contains roller-type free wheels, in
accordance with this invention
FIG. 3 (A) is a side view of the free wheel
arrangement;
FIG. (B) is a side view illustrating the free
wheel in forward motion;
FIG. (C) is a side view illustrating the free
wheel in backward or rearward motion;
FIG. 5 is a partial sectional view of the rear
hub and free wheel assembled together;
FIG. 6 is a perspective view broken away to ill-
ustrate the speed change mechanism provided in accordance
with an embodiment ox the invention; and
FIG. 7 (D, E and F) are diagrammatic views of the
speed change mechanism in first speed, second speed, and
third speed, respectively.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring more particularly to the drawings, which
illustrate a preferred embodiment of the invention, there
is shown in FIG. 1 a bicycle comprising propulsion levers
4 and speed change arms 3. These propulsion levers and
speed change arms are built in one piece and mounted on
the shaft portion 2 at the bottom of -the front frame 1 of
I
the bicycle. The one piece assembly of propulsion levers
4 and speed change arms 3 is pivotal mounted on the shaft
2 in such a manner that the propulsion levers 4 are movable
up and down alternatively (oscillate) by means of pedals 4'.
The propulsion levers 4 maintain a certain angle with respect
to the speed change arms 3. These arms are slightly curved
in an amount dependent upon dimensions of the frame and
chains 7" and link 14. Movement ox the link will therefore
be along the proper locus of curvature. Chains 7" are
connected with connecting bars 14 to the speed change arms
3. Guide rollers 13 support a see-saw cable 7'. Free wheels
lea of one-way clutch mechanisms with chain gears 7 are
mounted on the rear shaft portion 2' at the bottom of the
rear frame 1'. The rear wheel assembly at rear shaft
proton 2' is made up of an axle 5 and a hub 6, as shown
in the upper right corner of FIG. 3. A cam plate 8 with a
plurality of sloped indentations 8', equally distant from
each other along the cylindrical surface of the cam plate
8, is provided. The cam plate 8 is attached to the chain
gear 7. Each sloped indentation 8' is provided with a hard
roller 9 and spring 9'. The cam plate 8 is disposed in-
side a drum 11 having a latch 10 and paw 10' which form the
shape of the Greek letter, lambda. This assembly of the
free wheel ha is further assembled with a ratchet gear 12.
Two such gears 12 are provided at both ends of the axle.
The protruding end of the latch 10 fits into the square
notch I formed on the hub 6 under the bias of a spring 10'~
(see FIGS. 3 and 4). Ire paw 10' is caught by -the ratchet
gear 12 during backward motion. This causes the latch 10
to separate from the notch I The roller 9 is constricted
in the narrow part of the sloped indentation I under the
inner cylindrical surface of the drum 11 during forward
motion of the bicycle. This transmits the power of the
chain gear 7 to the hub 6 through the drum 11 (see FIGS. 3,
4, and 5). Several notches 6' may be provided so as to
enable more rapid preengagement when forward movement is
resumed.
The chain gears 7 at the ends of -the axle 5 have
chains 7" entrained thereon. One of the ends of these chains
are connected to a see-saw cable 7' which is entrained around
guide rollers 13. The other or free ends of the chains are
linked with connecting bars 14. Each of the connecting
bars is connected to a different speed change arm 3 by
means of a connecting pin 14' as shown in FIG. 2.
Each speed change arm 3 is equipped with pivotal
members disposed longitudinally thrilling in a row. These
pivotal members are in the form of triangular pieces 15
mounted at fixed pivots. Each triangular piece has a "U"-
shaped notch 15' at the apex of two sides of the triangle
thereof. The pivotal connection is made by a supporting
pin 16. Springs 16' bias the triangular pieces 15 downwardly
toward the bottom of the arms (see FIGS. 6 and 7). A cam
bar 17 in each arm is disposed for longitudinal movement
in the arm under the triangular pieces 15. The cam bar
has the same number of cam projections assay the number of
pieces 15. The cam bar 17 is connected to a cable or wire
19' which extends through a capstan 18' is turned by a
speed control knob 18. The knob 18 is assembled to a drum
which holds a ball 18"' biased by a spring 18"". The ball
is biased against holes 18" and the capstan 18'. By turning
the speed control knob 18, the cam bar 17 is moved to the
right or left, as viewed in FIGS. 6 and 7. Any one of the
pivotal pieces 15 is selectively pushed and extended by a
cam 17' on the cam bar 17 out of the edge of the speed change
arm 3 on which the connecting pin 14' is movable. Thus,
the connecting bar 14 is automatically caught into the "U"-
shaped notch 15' of the extended piece 15. The speed change
is effected by the connection of the connecting bar 14 at
different positions on the speed change arm 3.
In FIG. 3, a set of ball bearings 20 is disposed
in a seat 21 and held therein by a bearing race 22 which is
assembled to the axle 5 by a nut 23.
To ride the bicycle, an operator sits on the
saddle, holds the handle and puts his feet on the right
and left pedals 4'. The operator makes repeated up and
downward motion (oscillating motion). Then the speed change
arms 3 move forward and backward repeatedly according to the
angle which they make with the propulsion levers 4. The
speed change arms pull on the connecting bars 14 alternatively
thereby causing see-saw motion of the chain 7". The chain
gears 7 rotate in both directions alternatively. If the
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chain gear 7 is rotated clockwise, the cam plate 8 also rotates
in the same direction. The roller 9 rolls up into the narrow
space adjacent the sloped side of the indentation 8' and
is caught hard inside of the cylindrical surface of the
drum if of the free wheel ha. This constricts the drum
11 and the free wheel ha is rotated with the chain gear 7.
At this time, since the protruding end of the latch 10 in
the drum 11 is disposed in the square notch 6' on the hub
6, as shown in FIG. I, and hub 6 is also rotated in the
same direction, causing the bicycle to move forward.
If the chain gear 7 is rotated reversely by the
chain 7", or is stationary as during coasting, the roller
9 in the cam plate indentations is rolled down to the wider
part of the indentations and separated from the drum if of
the free wheel ha. Thus, the reverse rotating motion of
the chain gear 7 is not transferred to the drum. The hub 6
is still rotated forward by its rotational momentum without
being affected by the reversely rotating chain gear 7. When
the chain gear 7 is rotate in the propulsion direction
gain, the cam plate 8 and the drum if are held together and
the force is transmitted to the hub 6. There-fore, every
time the propulsion levers 4 are moved up and down, the force
imparted from their motion is transmitted to the chain gear
7 and the free wheels ha which are mounted at both ends
of the rear axle 5 and the bicycle runs forward continuously.
When speed change is required, the speed control
knob 18 is turned and the cam bar 17 is moved to extend the
first pivotal mounted piece 15 which is nearest to the
shaft 2 from among the plurality of pivotal pieces 15
which are disposed in a row in the speed change arm 3
as shown in FIG. I. Thus, the connecting pin 14' of
the connecting bar 14 is automatically caught into the
Unshaped notch 15' on the first piece 15 by the weight
of the connecting bar itself and the movements o-f the
speed change arm 3. This results in selecting the lowest
or first speed. us shown in FIG. I, the second pivotal
mounted piece 15 is extended and the connecting pin 14' of
the connecting bar 14 is caught into the second piece 15.
Then the somewhat faster, second speed is obtained. If
the third piece 15 is extended and the connecting pin 14 is
caught into the third piece as shown in FIG. I, a still
faster speed, the third speed, is obtained. In this manner
the speed change knob is turned and the position of the
connecting pin 14' caught on the speed change arm is changed
to vary the effective length of the speed change arm, and
thus to obtain the desired speed change.
When the bicycle is moved backward and the wheels
are rotated in reverse direction, the paw 10' is caught
into one of the teeth of the ratchet gear 12 and pushes up
on the latch 10, thereby separating it from the square
notch 6' of the hub 6 as shown in FIG. I. Thus, only
the hub 6 rotates while the free wheel ha and the chain
gear 7 are -free. The bicycle then can run backwards or
coast like a conventional bicycle without causing the up
I
and downward movement of the propulsion levers 4.
A bicycle in accordance with the present invention
provides the following advantages over conventional, as
well as other lever propelled bicycles. Because the bicycle
is designed in such a way that the roller type free wheel
attached with the chain gear is mounted at both ends of the
rear axle, the chains are fitted to the chain gears to provide
a see-saw action. The connecting bars connected to the
chains are linked to the speed change arms which form a one-
piece unit with the propulsion levers. The bicycle is
propelled by up and downward motion of the pedals. The angle
of this motion can be determined according to the operators
physical condition and convenience. Thus, the operator can
operate the bicycle with greater comfort and less strain.
Also, the force imparted by the up and downward motion of
the propulsion levers is fully -transmitted to the hub through
the chain gears and the free wheels. Thus, energy is not
wasted and much less force is required -to operate the big-
vale. Furthermore, the leg motion to cause the up and
downward movement of the propulsion levers is similar to
a persons normal walking motion. Therefore, even beginners
can easily operate the bicycle in the same manner as walking
in place without any special training. Since the flexibility
of the chain reduces shock caused by the momentum of the
speed change arm when its forward and backward motion is
stopped at its foremost and back most position, unreasonable
shocks to the propulsion devices in the rear shaft portion
are avoided and smooth power transfer through the roller
type free wheels can be achieved. The reliability and
e of the propulsion devices is enhanced and much longer
operation ox -the bicycle obtained
In addition, because many pivotal, the triangular
pieces are installed in a row on -the speed change arm and
any one piece is selectable extended out ox the arm with
the cam bar operated by the speed control knob, the
connecting pin located at the end ox the connecting bar is
caught into the piece which is extended and the desired
speed change can readily be obtained even while the bicycle
is in operation, depending on the road condition such as
uphill and downhill to assure more comfortable and convenient
operation ox the bicycle.
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