U.S. patent application number 13/502391 was filed with the patent office on 2012-08-23 for arrow shooting device.
Invention is credited to Kyung Sin Park.
Application Number | 20120210990 13/502391 |
Document ID | / |
Family ID | 43508728 |
Filed Date | 2012-08-23 |
United States Patent
Application |
20120210990 |
Kind Code |
A1 |
Park; Kyung Sin |
August 23, 2012 |
ARROW SHOOTING DEVICE
Abstract
The present invention relates to an arrow shooting device, and
more specifically to, a new arrow shooting device and a draw weight
adding method, wherein an arrow is shot not by a compound arrow or
a compound crossbow, which have been conventionally used, but by a
rubber band and a differential motion cam. The arrow shooting
device according to the present invention is formed in the straight
simple shape, wherein, as shown in FIG. 6, the rubber band having
superior elasticity is used rather than a limb in the energy
storage method thereof and the retraction speed of the rubber band
is converted using a differential motion cam or a differential
motion cam so as to be suitable for shooting the arrow. In
addition, it is possible to additionally hang the rubber band in
the state when drawing is finished, or pull the rubber band by
means of a winch, so that even people in general may shoot an arrow
with a strong draw weight. Therefore, the arrow shooting device is
light enough to easily be carried, is easy to manufacture and
repair, and has much storage power so that an arrow may be shot far
and shot straight. According to the present invention, it is
possible to resolve the conventional problems of the complicated
structure, heavy weight, noise and shock in the compound arrow and
the compound crossbow and reduce the weight for convenience in
movement.
Inventors: |
Park; Kyung Sin;
(Cheonan-si, KR) |
Family ID: |
43508728 |
Appl. No.: |
13/502391 |
Filed: |
November 23, 2010 |
PCT Filed: |
November 23, 2010 |
PCT NO: |
PCT/KR10/08284 |
371 Date: |
April 17, 2012 |
Current U.S.
Class: |
124/17 |
Current CPC
Class: |
F41B 5/0094 20130101;
F41B 5/1469 20130101 |
Class at
Publication: |
124/17 |
International
Class: |
F41B 7/00 20060101
F41B007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 3, 2009 |
KR |
10-2009-0119132 |
Claims
1. An arrow shooting device using a rubber band, comprising: a
differential motion cam including: a pair of outer pulleys each
having a groove for receiving a string; and an inner cam in which a
rubber inner string connected with the rubber band is fixed at a
fixing point of the outer side, and a spiral groove is
symmetrically formed, the radius of which decreasing as the rubber
inner string is inwardly wound, the inner cam having a straight
groove the radius of which is smallest at the central portion as it
meets the spiral groove.
2. An arrow shooting device using a rubber band, comprising: a
differential motion cam including: a pair of outer pulleys each
having a groove for receiving a strip; and an inner pulley in which
a rubber inner string connected with the rubber band is fixed at a
fixing point of the outer side, the rubber inner string being
inwardly wound after passing through an outer cylindrical portion,
and passing through a diamond-shaped groove at the central
portion.
3. An arrow shooting device according to claim 1, wherein there is
provided a trigger, and there is provided a way of increasing a
draw weight in such a way that a string is drawn, and a rubber band
is added and pulled toward the rubber band anchor and is
hooked.
4. An arrow shooting device according to claim 1, wherein there is
provided a trigger, and there is provided a winch helping stop the
rotation with a winch pawl in such way that a string is drawn, and
a winch cable connected with the rubber band is pulled by turning a
winch handle.
5. An arrow shooting device according to claim 1, wherein there is
provided a pair of string roller stopper which permit the movement
of the string in a horizontal direction when the string starts
moving after shooting, and limit the movement of the string in a
vertical direction and hooks and stops the string.
6. An arrow shooting device according to claim 1, wherein there is
provided a stopper cable one end of which is connected to a portion
where the rubber band inner string and the rubber band are
connected, and the other end of which is connected to a fixing
point of the body, thus stopping the contraction of the rubber
band.
7. An arrow shooting device according to claim 2, wherein there is
provided a trigger, and there is provided a way of increasing a
draw weight in such a way that a string is drawn, and a rubber band
is added and pulled toward the rubber band anchor and is
hooked.
8. An arrow shooting device according to claim 2, wherein there is
provided a trigger, and there is provided a winch helping stop the
rotation with a winch pawl in such way that a string is drawn, and
a winch cable connected with the rubber band is pulled by turning a
winch handle.
9. An arrow shooting device according to claim 2, wherein there is
provided a pair of string roller stopper which permit the movement
of the string in a horizontal direction when the string starts
moving after shooting, and limit the movement of the string in a
vertical direction and hooks and stops the string.
10. An arrow shooting device according to claim 2, wherein there is
provided a stopper cable one end of which is connected to a portion
where the rubber band inner string and the rubber band are
connected, and the other end of which is connected to a fixing
point of the body, thus stopping the contraction of the rubber
band.
Description
TECHNICAL FIELD
[0001] The present invention relates to an arrow shooting device,
and in particular to a new arrow shooting device which can shoot
arrows using a rubber band and a differential motion cam in such a
way to add a draw weight after drawing.
BACKGROUND ART
[0002] FIG. 1 shows an energy input of energy which is to be used
for shooting arrows.
[0003] The accumulations of energy input in a traditional bow are
shown in Graph TB of FIG. 1. When a person is of a large build, a
power stroke length increases, and a draw weight might increase
depending on the intensity of is exercise.
[0004] The compound bow has a large power stroke length as compared
with the motion of a limb by using an eccentric cam. A fast arrow
speed can be made by changing a recovery speed of a limb, and a lot
of energy can be accumulated when drawing a string, and an aiming
is easy with an adaptation of a let-off technology. The energy
input in terms of a compound bow is shown in Graph CB of FIG. 1,
and the compound bow can reach the maximum draw weight earlier than
a traditional bow, thus implementing an efficient energy
accumulation, and the aiming is easy now that the let-off
technology is adapted, in which technology the draw weight fast
decreases as the drawing is getting finished. The power stroke
length of the compound bow changes depending on the strong build
and the kinds of the releases; however it is similar with a
traditional bow.
[0005] The compound bow is adapted to a traditional type of a
crossbow, thus having developed a compound crossbow. It is known
that the compound to crossbow can accumulate the energy most as a
device which can load and shoot arrows with only the manpower
without using charge or compressed air among various devices so far
known to shoot arrows. The accumulation of energy in terms of the
compound crossbow is shown in Graph CC of FIG. 1. The compound bow
can be drawn with much larger draw weight and can be loaded and
hooked at a hooking member with the aid of both arms and a drawing
assistant tool as compared with a traditional bow or a compound bow
which is drawn with one arm, provided that magnificent weight and
durability are needed to have the power stroke length similar with
that of the compound bow, and the power stroke length is much
shorter than the compound bow.
[0006] The energy input and output procedures accumulated in the
compound bow are shown in CB of FIG. 12.
[0007] In terms of the energy output procedure, it has a mirror
image of the energy input procedure; however the total energy
output amount has 15% less than the energy input amount due to
friction resistance, noise, vibration, etc.
[0008] A rubber band is widely used in the industry thanks to its
good elasticity, and a rubber-mounted spear gun can shoot with a
lot of energy of 300 Joule.
[0009] A differential motion pulley is a pulley assembly in which
pulleys with different diameters are coupled and is generally used
for a speed change or a tensile force change.
[0010] In the present invention, a thing like a cam is also used in
addition to the type of a pulley, so the thing is called a
differential motion cam, and the differential motion pulley belongs
to a differential motion cam.
[0011] As shown in FIG. 2, a winch is directed to winding or
unwinding a winch cable WC the function of which is combined with a
ratchet function which allows a winch gear to rotate in one
direction using a winch pawl WP. The winch is a kind of a device
tugging a heavy thing by winding a rope on a cylinder, so it is
possible to lift or tug a heavy thing using a smaller power with
the aid of the principles of a pulley and a lever.
TECHNICAL PROBLEM
[0012] Since the invention of a compound bow was made in 1969, a
compound bow and a compound crossbow have advanced a lot; however
the compound bow and the compound crossbow have some problems as
follows.
[0013] The shooting is made after it is drawn only one time, so a
lot of energy cannot be stored.
[0014] A principle of a lever works at a portion from a pivot point
of a grip in a compound bow using a limb to the end of the limb in
such a manner that the pivot point becomes a supporting point
during the drawing, and the end of the limb becomes a force-applied
point, and besides another principle of a lever works, in which
principle a portion where a riser and a limb are connected becomes
a supporting point, and the end of the limb becomes a force-applied
point. Since more power is applied to the riser, so it is needed to
manufacture a stronger and durable compound bow, which brings in an
increased weight.
[0015] The compound bow or a crossbow with a limb is capable of
storing is energy above or below about 100 Joule, which energy is
to be used for shooting arrows. The rubber band used in a
rubber-mounted spear gun is capable of storing about 300 Joule,
which energy is used to shoot arrows, provided that the above
rubber band is limited in terms of the speed of contraction, so it
is not applicable to arrow shootings now that arrow should be shot
at a high speed.
TECHNICAL SOLUTION
[0016] Accordingly, it is an object of the present invention to
provide an arrow shooting device which adapts a method of shooting
arrows following storing a lot of energy and a method of converting
the accumulated energy into a fast speed using a differential
motion cam.
[0017] The method of storing a lot of energy is formed of a method
in which a plurality of rubber bands extendable with a users power
are prepared, and the rubber bands are pulled and hooked one by
one, thus accumulating energy, and a method in which more energy is
accumulated using a winch, and then arrows are shot, and the
contracting speeds of the rubber bands are converted using a
differential motion cam, thus shooting arrows for the purposes of
hunting or sports.
[0018] The present invention is directed to using a rubber band as
an energy storing means without using a limb, the rubber band being
extended and is contracted in the same direction as the body of the
arrow shooting device, so the principle of a lever in which a limb
works as a lever is not adapted. Since the force the body of the
arrow shooting device receives is smaller than a bow, the arrow
shooting device can be made lighter.
ADVANTAGEOUS EFFECTS
[0019] Since an ordinary person can shoot arrows by using a lot of
stored energy, a fast arrow speed can be obtained. Thanks to the
fast arrow speed, an accuracy rate and a hunting success rate can
be enhanced, and a straight trajectory can be obtained.
[0020] Since a rubber band is used as an energy storing medium, the
force is applied in the same direction as the body of the arrow
shooting device, so the twists of the body and the bending force
decrease a lot as compared with when using a limb, thus making the
body much lighter, which results in an easy-to-carry performance
and lowered manufacture costs.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is an energy accumulation graph of a traditional bow
(TB), a compound bow (CB) and a compound crossbow (CC).
[0022] FIG. 2 is a view illustrating a latchet function that a
winch (WP) is works on a winch gear (WG).
[0023] FIG. 3 is an upper, back and side view of a bow string
roller stopper (RS).
[0024] FIG. 4 is a side, back and bottom view of a differential
motion cam 1 (DC1) of an arrow shooting device according to the
present invention.
[0025] FIG. 5 is a side, back and bottom view of a differential
motion cam (DC2) of an arrow shooting device according to the
present invention.
[0026] FIG. 6 is a side and top view of an arrow shooting device
according to the present invention.
[0027] FIG. 7 is a view illustrating a drawing of an arrow shooting
device and an energy accumulation procedure following the drawing
according to the present invention.
[0028] FIG. 8 is a view illustrating an arrow shooting procedure of
an arrow shooting device according to the present invention.
[0029] FIG. 9 is a side and top view of an arrow shooting device
with a winch according to the present invention.
[0030] FIG. 10 is a view illustrating an energy accumulation
procedure of an arrow shooting device with a winch according to the
present invention.
[0031] FIG. 11 is a view of an arrow shooting procedure of an arrow
shooting device with a winch according to the present
invention.
[0032] FIG. 12 is an energy accumulation and discharge graph of an
arrow shooting device with a compound bow (CB), a differential
motion cam (DC1), and a differential motion cam 2 (DC2).
[0033] FIG. 13 is an energy accumulation and an energy discharge
graph when a winch is provided at an arrow shooting device with a
compound bow (CB), a differential motion cam 1 (DC1), and a
differential motion cam 2 (DC2).
DESCRIPTIONS OF REFERENCE NUMERALS OF KEY ELEMENTS OF THE
DRAWINGS
[0034] TB: traditional bow [0035] CB: compound bow [0036] CC:
Compound Crossbow [0037] IC: Inner Cam [0038] IP: Inner Pulley
[0039] OP: Outer Pulley [0040] DC1: Differential motion Cam 1
[0041] DC2: Differential motion Cam 2 [0042] RB: Rubber Band [0043]
S: String [0044] SA: String Anchor [0045] BA: Band Anchor [0046]
Ar: Arrow [0047] T: Trigger [0048] RS: Roller Stopper [0049] SC:
Stopper Cable [0050] IS: Inner String [0051] WC: Winch Cable [0052]
WG: Winch Gear [0053] WP: Winch Pawl [0054] FP: Fixing Point [0055]
Sh: Shield
BEST MODES FOR CARRYING OUT THE INVENTION
[0056] The preferred construction and operation according to the
present invention for achieving the above objects will be described
with reference to the accompanying drawings.
[0057] A bow string roller stopper (RS) is manufactured in the way
shown in
[0058] FIG. 2.
[0059] It is engaged in the way shown in FIG. 6 or 9, and a central
shaft is durably manufactured to stand a large power, and a groove
through which a string passes can move a bit in a horizontal
direction; however it should move in is a vertical direction to
allow an arrow to shoot in stable.
[0060] The differential motion cam 1 (DC1) is manufactured in the
ways of FIGS. 3 and 4.
[0061] The portions are prepared for fixing a bow string (S) and a
rubber band inner string (IS), and the fixing method generally
adapted in a compound can be used, and the fixing point (FP) means
a theoretical fixing point, not an actual fixing point. The both
sides of the inner pulley (IP) are made to form a cylindrical
shape, with their central portions being equipped with a groove to
allow a rubber inner string (IS) to be hooked in a full draw state.
The let-off is determined based on a radius from the groove to the
axis. If the groove is formed to be 30% of the radius of the inner
pulley (IP), the let-off becomes 70%.
[0062] The ratio of the radius of the outer pulley (OP) and the
radius of the outer pulley (OP) serves to determine the flying
speed of the arrow as compared with the rubber band contraction
speed. When the radius of the outer pulley (OP) is three times the
radius of the inner pulley (IP), the arrow can fly three times the
to rubber band contraction distance.
[0063] The rubber band (RB) has various thicknesses and lengths and
can be selected for a desired draw weight. Two rubber bands are
cut, and the rubber bands are connected with a bow string or
something, thus producing multiple rubber bands in loop shapes.
[0064] FIG. 6 is a side and top view illustrating a state that the
differential motion cam 1 (DC1) and the bow string roller stopper
(RS) are installed, and the rubber band (RB), the bow string (S),
the string anchor (SA), the rubber band anchor (BA), the trigger
(T), the string roller stopper (RS), the stopper cable (SC), and
the rubber band inner string (IS) are set.
[0065] The string S has one end connected with the fixing point
(FP) of the outer pulley (OP), and the other end connected to the
fixing point (FP) of the outer pulley (OP). The length of the
string (S) is determined so that the string (S) keeps tensioned
around the string anchor (SA) with a desired draw length when the
central groove of the inner pulley (IP) is positioned at the lowest
position.
[0066] The rubber band inner string (IS) is divided into two parts
the one part of which is fixed to the rubber band (RB), and the
other part of which is fixed to two fixing points (FP). The rubber
band inner string (IS) is installed in such a manner that the
rubber band (RB) can be fixed at the fixing point (FP) of the inner
pulley (IP) depending on the length for the rubber band (RB) to
have a proper initial tensile force from the moment the string (S)
is wound on the outer pulley (OP) and is hooked at the string
roller stopper (RS).
[0067] One side of the rubber band (RB) is fixed at the rubber band
anchor (BA), and the other side of the same is connected with the
rubber band inner string (IS).
[0068] As shown in FIG. 6, two more rubber bands (RB) might be
connected to the portion connected with the rubber band inner
string (IS). The rubber band to be pulled later is pulled without
using the differential motion cam, so it should be preferably
weaker than the engaged rubber band for easier pulling.
[0069] One side of the stopper cable (SC) is connected with the
fixing point (FP) of the body, and the other side of the stopper
cable (SC) is connected with the portion to which the rubber band
(RB) and the rubber band inner string (IS) are connected. The
length of the stopper cable (SC) and the installation of the fixing
point (FP) are determined so that the rubber band (RB) can be
loosened when the string (S) is fully drawn as shown in FIG. 8 and
the rubber band (RB) can have a proper initial tensile force when
the string (S) is wound on the outer pulley (OP) and is hooked at
the string roller stopper (RS).
[0070] FIG. 7 is a view illustrating a procedure of a drawing at
the arrow shooting device which has finished a basic setting and a
procedure that energy is further accumulated after drawing.
[0071] The string (S) hooked at the string roller stopper (RS) is
drawn and is hooked at the string anchor (SA) as shown in the
second drawing, and when the string (S) is pulled, the string (S)
wound on the outer pulley (OP) is unwound, and the differential
motion cam 1 (DC1) rotates in the clockwise direction, and the
rubber band inner string (IS) is wound on the inner pulley (IP),
and the rubber band (RB) extends by as much length as the wound
length. Since the rubber band inner string (IS) is fixed at the
outer side of the inner pulley (IP) at the initial stage of
drawing, it is wound on the cylindrical portion of the inner pulley
(IP); however the rubber band inner string (IS) gathers at the
central portion when the drawing is almost finished, so it becomes
naturally supported at the groove of the central portion of the
inner pulley (IP). When the rubber band inner string (IS) becomes
supported at the groove of the central portion of the inner pulley
(IP) just before the drawing is finished, the draw weight being
applied to the string (S) decreases to 30% as compared with just
before. In other words, 70% of the let-off effects can be obtained.
In this state, since the string S is supported by the string anchor
(SA), the force being applied to the trigger largely decreases, so
the durability of the trigger might be enhanced, along with the
increased accuracy rate.
[0072] The energy accumulation procedure following the drawing will
be described. One of the relaxed rubber bands (RB) is pulled and
hooked at the rubber band anchor (BA) as shown in the third
drawing, and the remaining rubber bands (RB) are pulled and hooked
at the rubber band anchor (BA) as shown in the fourth drawing.
[0073] FIG. 8 is a view illustrating a procedure that an arrow is
loaded by hooking at the string (S) after the energy accumulation
procedure is finished following the drawing, and the arrow is shot
by trigging the trigger after aiming.
[0074] When the string anchor (SA) falls as the trigger is
triggered, the rubber band contracts, and the differential motion
cam rotates in the counterclockwise direction, and the rubber band
inner string (IS), which has wound on the inner pulley (IP) during
the drawing is unwound, and the string (S) is wound on the outer
pulley (OP). When the radius of the outer pulley (OP) becomes three
times the radius of the inner pulley (IP), and the same rotations
are made, the moving distance of the string (S) becomes three times
the moving distance of the rubber band inner string (IS), so the
flying speed of the arrow becomes three times the contraction speed
of the rubber band based on the above principle.
MODES FOR CARRYING OUT THE INVENTION
[0075] 1. The differential motion cam 1 (DC1) and rubber band (RB)
are additionally pulled and hooked, which has been described in the
best mode for carrying out the invention.
[0076] 2. The differential motion cam 2 (DC2) and rubber band (RB)
are additionally pulled and hooked.
[0077] It is possible to obtain a linear increase effect in the
draw weight after the completion of the drawing with the aids of
the let-off effects and the hooking of additional rubber bands like
the differential motion cam 1 (DC1) of FIG. 12 in terms of the
energy accumulation and the energy output aspects when the
differential motion cam 1 (DC1) is used; however the energy
accumulation and energy output graphs similar with the traditional
bow are obtained, so the efficiency decreases as compared with the
compound bow. It is needed to change the design of the inner cam so
as to accumulate and output the energy in an efficient way like the
compound bow.
[0078] FIG. 5 is a side, back and bottom view illustrating the
differential motion cam 2 (DC2). The outer side of the inner cam
has a large radius, and the inner side has a small radius, and a
straight groove is formed at the central portion, by the
construction of which the radius can sharply decrease. Like the
differential motion cam 2 (DC2) of FIG. 12, it is possible to
obtain the effects same as the compound bow in terms of the energy
accumulation and let-off. to Since additional rubber bands are
engaged, thus increasing a linear increase effect in terms of the
draw weight in the let-off state. When an arrow is shot, it is shot
with a trajectory similar with the compound bow. The basic setting
method in case of the use of the differential motion cam 2 (DC2) is
the same as when the differential motion cam 1 (DC1) is used.
[0079] 3. The number of the rubber bands (RB): Even when the rubber
band (RB), which is basically engaged, has a tensile force stronger
than the rubber band (RB) which is additionally pulled, it can be
easily pulled with the aid of the differential motion cam 1 (DC1)
or the differential motion cam 2 (DC2). The rubber band (RB), which
is additionally pulled, is pulled without using the differential
motion cam 1 (DC1) or the differential motion cam 2 (DC2), it
should have a tensile force weaker than the basically engaged
rubber band. It is preferred that the number of the rubber band
(RB), which is to be additionally pulled, is not limited, but
2.about.4.
[0080] 4. The use of winch
[0081] FIG. 9 is a side and top view illustrating an arrow shooting
device which is drawn using a winch. The method for setting the
differential motion cam 1 (DC1), the string (S), the string roller
stopper (RS), the stopper cable (SC) and the rubber band inner
string (IS) is the same as the earlier setting method, provided
that as different matters, the rubber band with a strong tensile
force is basically used, and there is provided a shield Sh for
covering the rubber band, and one of the rubber band (RB) is
connected with the winch cable (WC). Since there is not a function
for additionally pulling the rubber band and hooking the same, it
is needed to select and engage a stronger rubber band which is
basically engaged. When there is a shield Sh for covering the
rubber band, it is helpful to support with one hand during the
aiming. One side of the rubber band (RB) is connected with the
winch cable (WC), and when the winch cable (WC) is wound by
rotating the winch handle (WH), it is easy to pull the rubber band
even though it has a stronger tensile force.
[0082] As shown in FIG. 2, a winch pawl (WP) is installed at the
winch, which leads to obtaining a ratchet function. The clockwise
rotation or the counterclockwise rotation can be implemented with
one winch pawl (WP).
[0083] FIG. 10 is a view illustrating a drawing procedure of the
arrow shooting device with a winch installed therein. The winch
gear (WG) can be rotated in the clockwise direction by pressing the
winch pawl (WP), and as the string (S) is pulled, the winch cable
(WC) can be wound without having the rubber band (RB) extended, so
a drawing can be made possible when a draw weight is very low. The
tensile force being applied to the string (S) can decrease to 30%
as compared to just before in such a manner that the rubber band
inner string (IS) is supported at the grove of the central portion
of the inner pulley (IP) just before the completion of the drawing.
In other words, it means that 70% of the let-off effect can be
obtained. In this state, since the string (S) remains supported by
the string anchor (SA), the force being applied to the trigger
significantly decreases, which leads to enhancing the durability of
the trigger, along with enhanced accuracy rate. The winch gear (WG)
can be made to rotate only in the counterclockwise direction by
pressing the winch pawl (WP) in the opposite direction after the
string (S) is hooked at the string anchor (SA) until the let-off
state is obtained, and then the winch gear (WG) is rotated in the
counterclockwise direction using the winch handle (WH). As the
winch cylinder rotates, the winch cable (WC) is wound on the winch
cylinder, and the rubber band is extended, and the draw weight of
the string (S) being in the let-off state increases.
[0084] FIG. 11 is a view illustrating an arrow shooting procedure
of an arrow shooting device with a winch installed therein. The
arrow (Ar) is loaded at the string (S) of the arrow shooting device
which has completed the drawing, and the cover is supported using
one hand, and the handle is held by the other hand, and then the
aiming is done, so the arrow is shot by trigging the trigger (T).
When the string anchor (SA) fells, the rubber band contracts, thus
pulling the rubber band inner string (IS). The rubber band inner
string (IS) wound on the inner pulley (IP) during the drawing is
unwound, and the differential motion to cam 1 (DC1) rotates
counterclockwise. The string (S) is wound on the outer pulley (OP)
as many turns as the rotation, so the arrow is shot. When the
radius of the outer pulley (OP) becomes three times the radius of
the inner pulley (IP), and the same rotations are made, the moving
distance of the string (S) becomes three times the moving distance
of the rubber band inner string (IS), so the flying speed of the
arrow becomes three times the contraction speed of the rubber band
based on the above principle.
[0085] Here the differential motion cam 2 (DC2) might be used
instead of using the differential motion cam 1 (DC1). It is
possible to have the energy accumulation and output aspects like
the compound bow in the same manner as in the differential motion
cam 2 (DC2) of FIG. 12 by variously changing the radius of the
groove of the first inner cam (IC) of the differential motion cam 2
(DC2).
[0086] FIG. 13 is a view illustrating an energy accumulation and
output when a winch is used.
[0087] The draw weight is very weak now that the rubber band is not
extended during the drawing.
[0088] The draw weight being in the let-off state vertically rises
as the rubber band is extended by turning the winch in the let-off
state following the drawing.
[0089] When the arrow is shot by trigging the trigger, the arrow
shooting device with the differential motion cam 1 (DC1) emits
energy with a trajectory similar with the traditional bow except
for the let-off, and the arrow shooting device with the
differential motion cam 2 (DC2) emits energy with a trajectory
similar with the compound bow.
[0090] Since the strong rubber band is pulled using the winch, an
ordinary person can store a lot of energy and easily shoot arrows
with the aid of the stored energy.
[0091] 5. The present invention serves to manufacture an arrow
shooting device which can shoot an arrow by using a release without
adapting a trigger device with the aid of the differential motion
cams such as a differential motion cam 1 (DC1) and a differential
motion cam 2 (DC2).
[0092] In the body with a simple-looking grip are disposed the
differential motion cam (DC1) or the differential motion cam 2
(DC2), the string roller stopper (RS), the rubber band (RB), the
string (S), the rubber band anchor (BA).
[0093] The release is used without the trigger being fixed at the
body, and if the differential motion cam 2 (DC2) is adapted, the
energy accumulation and output graphs are similar, so the drawing
feeling and let-off effects might be similar with the compound bow;
how performances might be a bit low now what the position of the
pivot point differs.
[0094] 6. The arrow shooting device with a smaller body might be
manufactured using a metallic spring instead of a rubber band.
INDUSTRIAL APPLICABILITY
[0095] The present invention is directed to obtaining a wanted
arrow speed by adjusting the ratio of an outer pulley radius and an
inner cam radius of the differential motion cam 1 (DC1) or the
differential motion cam 2 (DC2) which is adapted to increase the
contraction speed of the rubber band, and the draw weight can be
increased by the method of adding the draw weights. So, an ordinary
person can easily shoot arrows with the draw weight of hundreds of
pounds.
[0096] The present invention is directed to providing a
simple-looking straight structure by adapting a rubber band or a
strong spring instead of using a limb to store energy.
[0097] Much less air resistance is obtained as compared with a
conventional compound bow and a compound crossbow, so noises and
vibrations are low during the shooting.
[0098] With the help of the above-mentioned advantages, the arrow
shooting device of the present invention might substitute a
compound bow and a compound crossbow which are generally used for
the purposes of sports and hunting. When the present invention is
used for the purpose of a rubber spear gun, it is possible to
manufacture a rubber spear gun which is smaller than the
conventional rubber spear gun but has a lot of output energy.
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