U.S. patent application number 13/457114 was filed with the patent office on 2013-03-14 for projectile-launching implement having multi-stage draw.
The applicant listed for this patent is Richard Edward Asherman. Invention is credited to Richard Edward Asherman.
Application Number | 20130061839 13/457114 |
Document ID | / |
Family ID | 46028231 |
Filed Date | 2013-03-14 |
United States Patent
Application |
20130061839 |
Kind Code |
A1 |
Asherman; Richard Edward |
March 14, 2013 |
PROJECTILE-LAUNCHING IMPLEMENT HAVING MULTI-STAGE DRAW
Abstract
A bow includes an upper limb and a lower limb. A restraint
system stores energy in the upper limb and the lower limb via
drawing a tensioning cable to a charged position. A bow string
releases the energy stored in the upper limb and the lower limb by
the restraint system when the bow string is drawn to a ready
position.
Inventors: |
Asherman; Richard Edward;
(Cody, WY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Asherman; Richard Edward |
Cody |
WY |
US |
|
|
Family ID: |
46028231 |
Appl. No.: |
13/457114 |
Filed: |
April 26, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61479290 |
Apr 26, 2011 |
|
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|
Current U.S.
Class: |
124/25.6 ;
124/31; 124/35.2 |
Current CPC
Class: |
F41B 5/1469 20130101;
F41B 5/10 20130101 |
Class at
Publication: |
124/25.6 ;
124/31; 124/35.2 |
International
Class: |
F41B 5/18 20060101
F41B005/18; F41B 5/14 20060101 F41B005/14; F41B 5/10 20060101
F41B005/10 |
Claims
1. A projectile-launching device positionable in a release position
wherein the device is unable to launch a projectile, a ready
position wherein the device is able to launch a projectile, and a
hold position located between the release position and the ready
position, wherein the projectile-launching device comprises: a
restraint system for preventing the device from being moved from
the hold position directly to the release position; and a release
mechanism for disengaging the restraint system so as to allow the
device to be returned to the release position directly from the
ready position, wherein the release mechanism disengages the
restraint system when the device is moved to the ready position,
and wherein the device is unable to launch the projectile from the
hold position.
2. The projectile-launching device of claim 1, further comprising a
plurality of deflectable arms and at least one tensioning member
connecting the plurality of arms.
3. The projectile-launching device of claim 2, wherein the
plurality of deflectable arms comprise: a superior primary limb and
an inferior primary limb; and a superior secondary limb and an
inferior secondary limb; and wherein at least one tensioning member
comprises: a primary cable connecting the superior primary limb and
the inferior primary limb; and a secondary cable connecting the
superior secondary limb and the inferior secondary limb.
4. The projectile-launching device of claim 3, wherein the
restraint system holds the superior secondary limb and the inferior
secondary limb in a deflected position, when the secondary cable is
moved to a second cable drawn position.
5. The projectile-launching device of claim 4, wherein the release
system deactivates the restraint system when the superior primary
limb and the inferior primary limb are moved to a deflected
position.
6. The projectile-launching device of claim 4, wherein the release
system deactivates the restraint system when the primary cable is
moved to a primary cable drawn position.
7. The projectile-launching device of claim 3, wherein the
restraint system comprises a ratchet and pawl located on at least
one of the secondary limbs.
8. The projectile-launching device of claim 7, wherein the release
mechanism comprises an engagement element located on at least one
of the primary limbs.
9. The projectile-launching device of claim 3, wherein the primary
cable is configured to releasably engage a projectile.
10. The projectile-launching device of claim 2, further comprising
a gearbox and a gear system comprising a tensioning member pulley
located in the gearbox, wherein the tensioning element is wrapped
at least partially around the tensioning member pulley.
11. The projectile-launching device of claim 10, wherein the gear
system further comprises a ratchet and a pawl releasably engaging
the ratchet.
12. The projectile-launching device of claim 11, wherein the
release mechanism disengages the ratchet from the pawl.
13. The projectile-launching device of claim 12, wherein the
release mechanism comprises a trigger.
14. The projectile-launching device of claim 12, wherein the
release mechanism disengages the ratchet from the pawl when a bow
string is moved from an undrawn position to an drawn position.
15. The projectile-launching device of claim 11, wherein the gear
system further comprises an actuator pulley and an actuator cable
wrapped at least partially around the actuator pulley.
16. The projectile-launching device of claim 15, wherein a free end
of the actuator cable extends from the gearbox.
17. A method of launching a projectile with a projectile-launching
device comprising a release position, a hold position, and a ready
position, the method comprising: moving the device from the release
position to the hold position, wherein when in the hold position,
the device is prevented from returning to the release position and
from launching the projectile from the hold position; moving the
device from the hold position to the ready position, wherein when
in the ready position, the device is enabled to return to the
release position and to launch the projectile; and releasing the
device from the ready position to the release position to launch
the projectile.
18. The method of claim 17, further comprising automatically
engaging a restraint mechanism when the device is moved from the
release position to the hold position.
19. The method of claim 18, further comprising automatically
disengaging the restraint system when the device is moved to the
ready position.
20. A bow comprising: an upper limb and a lower limb; a tensioning
cable and restraint system whereby energy may be stored in the
upper limb and the lower limb via drawing the tensioning cable to a
charged position; and a bow string that, via drawing the bow string
to a ready position, releases the energy stored in the upper limb
and the lower limb by the restraint system.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and the benefit of U.S.
Provisional Patent Application Ser. No. 61/479,290, filed Apr. 26,
2011, entitled "Projectile-Launching Implement Having Multi-Stage
Draw," the disclosure of which is hereby incorporated by reference
herein in its entirety.
INTRODUCTION
[0002] Projectile launching devices (such as bows) are used to
launch projectiles (arrows) at targets. In general, bows that
launch with greater force require greater strength on the part of
the user to draw the bow back into a ready position (i.e., the draw
weight is higher). While this may be acceptable for an able-bodied
user, users who are less strong may not be able to easily draw the
bow, or hold it in the ready position while aiming. To address this
problem, compound bows that utilize a pair of pulleys or cams to
reduce the force that the user must overcome have been developed.
These bows, however, may not provide sufficient advantages for
certain users, for example, youth that are learning the skills of
archery, or the disabled who wish to enjoy the sport.
SUMMARY
[0003] In one aspect, the technology relates to a
projectile-launching device positionable in a release position
wherein the device is unable to launch a projectile, a ready
position wherein the device is able to launch a projectile, and a
hold position located between the release position and the ready
position, wherein the projectile-launching device includes: a
restraint system for preventing the device from being moved from
the hold position directly to the release position; and a release
mechanism for disengaging the restraint system so as to allow the
device to be returned to the release position directly from the
ready position, wherein the release mechanism disengages the
restraint system when the device is moved to the ready position,
and wherein the device is unable to launch the projectile from the
hold position. In an embodiment, the projectile-launching device
further includes a plurality of deflectable arms and at least one
tensioning member connecting the plurality of arms. In another
embodiment, of the projectile-launching device, the plurality of
deflectable arms include: a superior primary limb and an inferior
primary limb; and a superior secondary limb and an inferior
secondary limb; and at least one tensioning member includes: a
primary cable connecting the superior primary limb and the inferior
primary limb; and a secondary cable connecting the superior
secondary limb and the inferior secondary limb. In yet another
embodiment, the restraint system holds the superior secondary limb
and the inferior secondary limb in a deflected position, when the
secondary cable is moved to a second cable drawn position. In still
another embodiment, the release system deactivates the restraint
system when the superior primary limb and the inferior primary limb
are moved to a deflected position.
[0004] In an embodiment of the above aspect, the release system
deactivates the restraint system when the primary cable is moved to
a primary cable drawn position. In another embodiment of the
projectile-launching device, the restraint system includes a
ratchet and pawl located on at least one of the secondary limbs. In
another embodiment, the release mechanism includes an engagement
element located on at least one of the primary limbs. In yet
another embodiment, the primary cable is configured to releasably
engage a projectile. In still another embodiment, the
projectile-launching device, further includes a gearbox and a gear
system including a tensioning member pulley located in the gearbox,
wherein the tensioning element is wrapped at least partially around
the tensioning member pulley. In another embodiment, the gear
system further includes a ratchet and a pawl releasably engaging
the ratchet.
[0005] In another embodiment of the above aspect, the release
mechanism disengages the ratchet from the pawl. In another
embodiment, the release mechanism is a trigger. In yet another
embodiment, the release mechanism disengages the ratchet from the
pawl when a bow string is moved from an undrawn position to a drawn
position. In still another embodiment, the gear system further
includes an actuator pulley and an actuator cable wrapped at least
partially around the actuator pulley. In another embodiment, a free
end of the actuator cable extends from the gearbox.
[0006] In another aspect, the technology relates to a method of
launching a projectile with a projectile-launching device having a
release position, a hold position, and a ready position, the method
including: moving the device from the release position to the hold
position, wherein when in the hold position, the device is
prevented from returning to the release position and from launching
the projectile from the hold position; moving the device from the
hold position to the ready position, wherein when in the ready
position, the device is enabled to return to the release position
and to launch the projectile; and releasing the device from the
ready position to the release position to launch the projectile. In
an embodiment, the method further includes automatically engaging a
restraint mechanism when the device is moved from the release
position to the hold position. In another embodiment, the method
further includes automatically disengaging the restraint system
when the device is moved to the ready position.
[0007] In another aspect, the technology relates to a bow having:
an upper limb and a lower limb; a tensioning cable and restraint
system whereby energy may be stored in the upper limb and the lower
limb via drawing the tensioning cable to a charged position; and a
bow string that, via drawing the bow string to a ready position,
releases the energy stored in the upper limb and the lower limb by
the restraint system.
[0008] Accordingly, the present technology utilizes components that
allow for a multi-stage draw of a bow. The user draws the bow
string back to a first or hold position, wherein release of the bow
string at the hold position will not launch the projectile;
instead, the bow will hold or otherwise store the energy. If used
in a compound bow configuration, one embodiment contemplates
utilizing a pawl or other locking element that will lock one of the
cams in place. To release the projectile, the user must then draw
the bow string to a second position, where the pawl or locking
mechanism is disengaged, thereby allowing the projectile to be
launched upon release of the bow string. This second position may
be referred to as a ready or armed position. Any number of draw
stages may be utilized. In certain cases, the number of stages may
be limited by the size of the projectile-launching implement, the
desired weight of the implement, or other factors.
[0009] In another embodiment, pairs of pulleys or cams (a
dual-pulley pair configuration) on a bow system may be used to
reduce the draw weight required for each stage of the draw. Even
though the draw weight is reduced in each draw stage, the
projectile launch force is unaffected because of the multi-stage
draw required to use the bow. In certain embodiments, in fact, the
projectile launch force may be higher than that of existing
compound bows utilizing a single pair of pulleys.
[0010] Another possible solution for reducing the effective draw
weight is to utilize a reducing gear. The draw weight for each
stage may be reduced by any desired ratio, but in certain
embodiments, a draw weight reduction of half for each of the two
draws may be desirable. In such an embodiment, as the user draws
the bow to full draw, the limbs would only move about 50% of the
full movement. The user would only feel 50% of the weight based on
a 2:1 reduction. A ratchet and pawl system would hold the weight of
the first draw at the first or hold position. The ratchet and pawl
system would release towards the end of the second draw, at the
second or ready position. In practice, a user would draw 60 lbs.,
twice, in order to have an effective release weight of 120 lbs. One
advantage of this reducing gear configuration includes reducing the
number of moving parts that would need to be synched and tuned to
obtain the desired results. Losses due to friction are also
substantially reduced. As described above with regard to the
dual-pulley pair configuration, any number of draw stages may be
utilized. In certain cases the number of draw stages may be limited
by the size of the projectile-launching implement, manufacturing
costs, desired implement weight, etc. Other embodiments utilizing
different numbers of stages, reductions, etc. are contemplated and
described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] There are shown in the drawings, embodiments which are
presently preferred, it being understood, however, that the
technology is not limited to the precise arrangements and
instrumentalities shown.
[0012] FIGS. 1A-1I depict side views of a compound bow having a
multi-stage draw in various positions.
[0013] FIG. 2 depicts a side view of a pawl for use in a bow having
a multi-stage draw.
[0014] FIG. 3 depicts a side view of a ratchet for use in a bow
having a multi-stage draw.
[0015] FIG. 4 depicts a partial enlarged perspective view of the
compound bow of FIG. 1A.
[0016] FIG. 5A depicts a perspective view of a compound bow having
a multi-stage draw.
[0017] FIGS. 5B and 5C depict an end view and a side view,
respectively, of the compound bow of FIG. 5A.
[0018] FIG. 6 depicts an enlarged top view of a gear system
utilized in a bow having a multi-stage draw.
[0019] FIGS. 7A-7C depict enlarged perspective views of sections of
the gear system of FIG. 6.
DETAILED DESCRIPTION
[0020] Referring to FIGS. 1A to 1I, one embodiment of a
projectile-launching device in the form of a compound bow 100 is
shown. The order of the figures is presented such that they
progress sequentially through the various states of operation of
the compound bow 100 to show differences and interactions among
relevant design features. For the purpose of clarity, a secondary
cable 182 and a portion of a primary cable 180 are depicted in FIG.
1A. It should be noted that both cables 180, 182 are strung
generally as is typical for compound bows, unless otherwise
indicated below. In the remaining figures, either cable is
depicted, depending on their relevance to description. The position
of the cable that is not depicted in each figure would be apparent
to a person of skill in the art.
[0021] Referring to FIG. 1A, the compound bow 100 is shown in a
static equilibrium position before the bow 100 has been drawn in
any way. This position may be generally referred to as the release
position. Because this is static state of the bow 100, FIG. 1A is
primarily used for reference to identify the basic design features
of the bow 100.
[0022] In the embodiment shown, the compound bow 100 includes a
riser 150 defining a grip 152 and an arrow shelf 154. The grip 152
is shaped such that an archer's hand can grasp and support the
compound bow 100 in all of the various operating states. The arrow
shelf 154 supports a projectile, such as an arrow (not shown) while
the compound bow is being drawn from the release position to a
ready position, and during firing. The riser 150 further includes a
pair of limb pockets 158, 160 disposed at opposite ends of the
riser body 150. In one embodiment, the limb pockets 158, 160 are
integral to the riser body 150. In an alternative embodiment, the
limb pockets 158, 160 are separate components that are operably
attached to the riser body 150.
[0023] The compound bow 100 also includes two pairs of deflectable
arms. The first pair of arms includes a superior primary limb (SPL)
102 and an inferior primary limb (IPL) 104. The second pair of
arms, which are located between the primary limbs 102, 104 include
a superior secondary limb (SSL) 106 and an inferior secondary limb
(ISL) 108. In this description, the terms "superior" and "inferior"
refer to the position of the limbs relative to each other and to
are used distinguish the limbs from each other. The terms "upper,"
"lower," "top," and "bottom," may also be used as those terms are
typically understood. Of course, if the technologies described
herein are used in a crossbow application, the terms "first,"
"second," "left," and "right" may be used. In the depicted
embodiment, each of limbs 102-108 includes two parallel identical
arms. However, only one of each parallel arm is viewable in FIGS.
1A-1I because the views are from the side of the compound bow 100
wherein one arm is behind the other parallel arm. However, this
arrangement can be readily seen in FIG. 4, described below.
[0024] FIG. 4 depicts a partial enlarged view of a portion of the
IPL 104 and ISL 108. The IPL 104 includes two arms 104', and the
ISL 108 includes two arms 108'. In other embodiments, each of the
IPL 104 and ISL 108 may be forked, such that there is a single
point of connection for each limb 104, 108 at the lower limb pocket
160, and each limb 104, 108 splits at a location distal therefrom.
The axle 178 spans the arms 108' of the ISL 108 and provides a
point of rotation for both the cam 106 and the ratchet 118. A pawl
axle 120e spans the arms 108' of the ISL 108 to support the pawl
120. An engagement element or release element 122 extends from the
IPL 104, as described below.
[0025] Returning to FIG. 1A, each of the limbs 102-108 is
configured to deflect and thus store potential energy that will be
released into a projectile when the compound bow 100 is allowed to
move from the ready position to the release position. To enable
such a function, the limbs 102-108 are each connected to the riser
150 via the limb pockets 158, 160. As shown, a first end 102a of
the SPL 102 and a first end 106a of the SSL 106 are received into
limb pocket 156.
[0026] In one embodiment, a limb bolt 158 extends through the limb
pocket 156 and the limbs 102, 106 to retain the limbs 102, 106
within the pocket 156. In a similar fashion, a first end 104a of
the IPL 104 and a first end 108a of the ISL 108 are received into
limb pocket 160. In one embodiment, a limb bolt 162 extends through
the limb pocket 160 and the limbs 104, 108 to retain the limbs 104,
108 within the pocket 162. It is noted that other means may be used
for retaining the limbs 102-108 within the limb pockets 156, 160
besides with single bolts 158, 162. For example, the limbs 102-108
may be secured by a plurality of bolts or by non-mechanical
elements, such as high-strength chemical adhesives or combinations
of various elements.
[0027] In one embodiment, the limb pockets 158, 160 are provided
with rounded edges and/or cushioning material to reduce potential
point stress onto the limbs 102-108 by the limb pockets 158, 160.
Reducing point stress locations in the assembly will reduce the
chance of catastrophic failure of the compound bow 100. Such
features are especially beneficial where the limb pockets 158, 160
are formed from metal and the limbs are formed from a composite or
other plastic material.
[0028] Still referring to FIG. 1A, each limb 102-108 is provided
with a rotatable cam 110-116. The rotatable cams 110-116 are
specifically shaped for providing mechanical advantage when the
compound bow is placed in the ready position such that a reduced
holding force is required to retain the bow 100 in the ready
position. When the cams 110-116 are in this position, they can be
referred to as being in "let off" or being in the "let off
position." This function allows an archer to hold the compound bow
100 in the ready position for a longer period of time so that the
archer can steady the bow 100 more effectively for enhanced
accuracy.
[0029] As shown, the superior primary limb cam 110 is provided at a
second end 102b of the limb 102. The cam 110 is operably connected
to the parallel arms of the SPL 102 by an axle 172 which spans the
arms. Likewise, the inferior primary limb cam 112 is at a second
end 104b of the IPL 104. The cam 112 is operably connected to the
parallel arms of the IPL 104 by an axle 174 which spans the arms.
The superior secondary limb cam 114 is provided at a second end
106b of the SSL 106. The cam 114 is operably connected to the
parallel arms of the SSL 106 by an axle 176 which spans the arms.
The inferior secondary limb cam 116 is provided at a second end
108b of the ISL 108. The cam 116 is operably connected to the
parallel arms of the ISL 108 by an axle 178 which spans the
arms.
[0030] As stated above, the compound bow 100 includes a primary
cable 180. The primary cable 180 is connected to the SPL 102 at a
first end 180a and to the IPL 104 at a second end 180b. In one
embodiment, each end 180a, 180b of the primary cable 180 may be
split such that each split end may be attached to each of the limbs
102, 104 at the axles 172, 174. As typical for compound bows, the
primary cable 180 wraps around each of the cams 110 and 112 between
the two ends 180a, 180b. This arrangement allows for the primary
limbs 102, 104 to be drawn into the ready position by sufficiently
pulling the portion of the primary cable 180 extending between the
two cams 110, 112.
[0031] In a similar arrangement to the primary cable, the compound
bow 100 includes a secondary cable 182. The secondary cable 180 is
connected to the SSL 106 at a first end 182a and to the ISL 108 at
a second end 182b. In one embodiment, each end 182a, 182b of the
secondary cable 182 may be split such that each split end may be
attached to each of the parallel limbs 106, 108 at the axels 176,
178. As typical for compound bows, the secondary cable 182 wraps
around each of the cams 114 and 116 between the two ends 182a,
182b. This arrangement allows for the secondary limbs 106, 108 to
be drawn into a hold position by sufficiently pulling the portion
of the secondary cable 182 extending between the two cams 114,
116.
[0032] Still referring to FIG. 1, the compound bow further includes
a ratchet 118 and a pawl 120. The ratchet 118 and the pawl 120 form
a restraint system for retaining the secondary limbs 106, 108 in
the hold position after the secondary cable 182 has drawn the limbs
106, 108. In the depicted embodiment, the ratchet 118 is operably
coupled to the inferior secondary limb cam 116. In one embodiment,
the ratchet 118 and cam 116 are rotatable with respect to each
other. The ratchet 118 and the cam 116 may be operably coupled such
that rotation of the cam 116 is constrained by the ratchet 118 such
that, when the ratchet 118 is prevented from rotating, the
secondary limbs 106, 108 are prevented from moving from the hold
position. The ratchet 118 may be operably coupled to the cam 116 by
a torsion spring.
[0033] As best seen in FIG. 3, ratchet 118 includes circumferential
groove 118a that guides the secondary cable 182 and maintains
alignment with respect to the thickness of the ratchet 118. In one
embodiment, the groove 118a is a concave groove. The ratchet 118 is
also provided with a ratchet tooth 118b configured to mate with a
corresponding ridge 120c on a pawl 120. The tooth 118b also can be
configured to prevent misalignment with the ridge 120c. Adjacent to
the ratchet tooth 118b is a guide ramp 118c that guides the pawl
120 over the ratchet 118 before engaging with the tooth 118b. In
order allow mounting and rotation of the ratchet 118, an axle hole
118d is provided through which axle 178 may extend. In one
embodiment, axle hole 118d is provided with a press-fit sleeve
bearing. The ratchet 118 is provided with an anchor hole 118e and
an anchor pin 118f for securing the second end 182b of the
secondary cable. Alternative embodiments of the ratchet 118 may not
include the groove 118a or anchor hole 118e.
[0034] Referring to FIG. 2, the pawl 120 is shown in greater
detail. The pawl 120 includes a pawl release 120a configured to
engage with a corresponding contact surface 122 associated with the
IPL 108 to release the pawl 120 from the ratchet tooth 118b. The
pawl includes a rounded backing 120b and a ridge 120c for reducing
stress concentrators and engaging with the ratchet tooth 118b,
respectively. In the embodiment shown, and as best seen in FIG. 4,
the pawl 120 is rotatably mounted between the parallel inferior
secondary limbs 108 via an axle hole 120d and a corresponding axle
120e.
[0035] Returning back to FIG. 1A, each of the limbs 102-108 may be
provided with a respective friction reducer 124-130. The friction
reducer 124-130 is formed from a low friction material and acts to
reduce friction between the superior limbs 102, 106 and between the
inferior limbs 104, 108. As shown, a friction reducer 124 is
provided on a lower surface of the SPL 102 while a corresponding
friction reducer 130 is provided on an upper surface of the SSL
106. Accordingly, instead of the limbs 102, 106 coming into direct
contact with each other when sufficiently drawn, the friction
reducers 124, 128 are brought into contact with each other.
Similarly, a friction reducer 126 may be provided on an upper
surface of the IPL 104 while a corresponding friction reducer 128
may be provided on a lower surface of the ISL 108. Accordingly,
instead of the limbs 104, 108 coming into direct contact with each
other when sufficiently drawn, the friction reducers 126, 130 are
brought into contact with each other. In such a configuration, the
compound bow 100 will be more efficient due to a lower energy loss
through friction between the adjacent limbs. In one embodiment, the
friction reducers are ultra-high molecular weight (UHMW)
polyethylene tape, though other materials are contemplated.
[0036] Referring to FIG. 1B, the compound bow 100 is shown when the
secondary cable 182 connecting the superior and inferior secondary
limb cams 114, 116 has been nearly fully drawn. This is considered
to be the secondary draw phase because only the secondary limbs
106, 108 and associated cams 114, 116 are affected through movement
of the secondary cable 182. The act of drawing the secondary cable
182 requires the archer to apply a force (draw weight) over a
distance (draw length). The draw length increases as the draw
weight increases. The friction between the secondary cable 182 and
the cams 114, 116 cause the SSL cam 114 and the ISL cam 116 to
rotate clockwise and counterclockwise, respectively. These cams
114, 116 are connected via the secondary cable 182 that squeezes
the secondary limbs 106, 108 together, elastically deforming the
limbs 106, 108 as a result of the cam rotations. The work done by
the archer to apply the required force over the distance necessary
to deflect the secondary limb sets 106, 108 is stored in the
deflected limbs in the form of strain energy. In one embodiment,
the ISL cam 116 is connected to the ratchet 118 with a torsion
spring (not shown) which allows the two to rotate together as a
result of drawing the secondary cable 182. The SSL 106 and the ISL
108 are shown in their deflected positions in FIG. 1B. Accordingly,
the SSL and ISL cams 114, 116 and ratchet 118 are shown in their
rotated positions. Because the primary cable 180 remains undrawn,
the SPL 102 and the IPL 104 along with their respective cams 110,
112, all remain in their equilibrium positions.
[0037] Referring to FIG. 1C, the compound bow 100 is shown at a
point slightly further along in the secondary draw phase. Note the
secondary cable 182 is not depicted. In this state, the pawl 120 is
in contact with, but not yet engaged with the ratchet 118. In one
embodiment, a light torsion spring (not shown) is provided to keep
the pawl 120 in contact with the ratchet 118 while the ratchet 118
is rotating but does not impede the rotation of the ratchet 180. In
an alternative embodiment, once drawn to this position, the
secondary cable 182 may be slowly returned to its equilibrium
position. In such an embodiment, a torsion spring (not shown)
attaching the ratchet 118 to the ISL cam 116 may be provided to
cause the ratchet 118 to rotate clockwise. The clockwise rotation
of the ratchet 118 effectively takes up the slack in the secondary
cable 182 while maintaining a sufficient amount of tension in the
cable 182 to keep the SSL cam 114 and the ISL cam 116 fully rotated
which keeps the SSL 106 and ISL 108 in their maximum deflected
positions. By keeping the secondary limb sets 106, 108 fully
deflected, this preserves the strain energy stored in the secondary
limb sets 106, 108.
[0038] Turning to FIG. 1D, and continuing with embodiment of the
bow that does not include the above-described secondary cable slack
take-up technology, the compound bow 100 is shown in a point even
further along in the secondary draw phase. The ratchet 118 has
rotated such that the pawl 120 slides over the ratchet tooth guide
ramp 118c. Once the pawl 120 has passed the edge of the ratchet
tooth 118b, the light torsion spring (not shown) attached to the
pawl 120 forces it back into contact with the surface of the
ratchet 118.
[0039] Referring to FIG. 1E, the bow 100 is shown after the drawn
of the secondary cable 182 has been completed by the archer, thus
placing the secondary limbs 106, 108, respective cams 114, 116, and
cable 182 under the mechanical control of the release mechanism. As
shown, the pawl 120 and ratchet 118 are engaging one another to
store the strain energy input from the initial draw phase in the
deflected secondary limbs 106, 108. Rotation of the ratchet 118
and, therefore, separation of the limbs 106, 108 is impeded by the
pawl 120. The convex ridge 120c on the surface of the pawl 120 that
contacts the ratchet 118, mates to the geometrically opposite
concave surface on the ratchet tooth 118a and the two lock together
as the pawl 120 is compressed between the ratchet tooth 118 and the
axle 120e locating the pawl 120 on the ISL 108. At this point, the
archer will knock an arrow and prepare to initiate the primary draw
phase in preparation to fire. It is noted that the surfaces on the
ridge 120c and the tooth 118b do not necessarily have to be convex
and concave, respectively. For example, the ridge 120c could have a
concave or flat surface while the tooth 118b could have a convex or
flat surface.
[0040] In some embodiments, it is desired to limit the initial
secondary draw phase to a single cycle, especially where
catastrophic failure may be possible with repeated cycles. One way
in which the initial secondary draw phase may be limited to a
single cycle is facilitated by the geometry of the pawl 120 and
ratchet mechanism 118. Specifically, the single tooth 118b on the
ratchet 118 can be configured to provide only one contact surface
for the pawl 120 and ratchet 118 to engage. Additionally, the
location of the anchor hole 118f where the secondary cable 182 is
attached to the ratchet 118 allows the cable 182 to block the
contact surfaces (e.g. 118b, 120c) in the event that the ratchet
118 could be made to complete an additional complete rotation.
Furthermore, the attachment of the ratchet 118 to the ISL cam 116
restricts the degree to which the ratchet 118 can rotate. As such,
the compound bow can be configured with multiple safety features in
that the secondary cable would create a barrier between the contact
surfaces so the pawl 120 could not engage the ratchet tooth 118b to
store that energy.
[0041] Referring to FIG. 1F, the compound bow 100 is shown near the
conclusion of the primary draw phase at a point when the primary
cable 180 is almost fully drawn. In this figure, the SSL 106, and
ISL 108 are still in the deflected position, held in place by the
interaction between the pawl 120 and ratchet 118 as described
previously. Additionally, the SPL 102 and IPL 104 are now also
being deflected. However, the deflection of these sets of limbs
102, 104 is a result from the interactions between the primary
cable 180, SPL cam 110, and IPL cam 112, similar to the
interactions described with respect to the secondary elements. As
the SPL 102 and IPL 104 continue deflecting, their inner surfaces
begin to contact the outer surfaces of the superior and inferior
secondary limb sets. Friction at the interface of these contact
surfaces is a source of inefficiency for the system. When the bow
100 is eventually fired, some of the potential energy stored in the
bow will be converted into heat, noise, and vibration rather than
being converted into kinetic energy used to accelerate the arrow.
As stated previously, friction reducers 124-130, may be applied to
these contact surfaces to reduce these losses due to friction.
[0042] FIG. 1G illustrates the interaction between the pawl 120 and
ratchet 118 immediately following completion of the primary draw
phase while the archer is holding the primary cable 180 at full
draw. In this figure, the SPL cam 110 and IPL cam 112 have achieved
their maximum rotations, and are in a let off state. The primary
limbs 102, 104 have reached their maximum deflection and the pawl
pressure release 120a has been contacted by an IPL contact surface
122 causing the pawl 120 to rotate about its axle 120e, disengaging
the pawl 120 from the ratchet tooth 118b. The IPL contact surface
122 may be on a surface of the IPL 104 or a projection mounted to
or between the parallel arms that make up the IPL 104. At this
point the bow 100 is ready to fire. Some time is usually taken by
the archer to steady the aim and ensure a clean shot.
[0043] FIG. 1H shows the configuration of the bow 100 just prior to
the archer releasing the primary cable 180 and firing an arrow. In
this figure, the ratchet 118 has rotated a small amount in the
counterclockwise direction, in embodiments where the secondary
cable 182 is spooled around the ratchet 118, some of the secondary
cable 182 is unspooled. As this happens, the SSL cam 114 and the
ISL cam 116 rotate a small amount allowing the secondary limb sets
106, 108 to push outwards against the primary limbs 102, 104. This
allows the secondary limbs 106, 108 to discharge energy to the
system, meaning that the energy stored by the initial secondary
draw phase has been released from the mechanical control of the
pawl 120 and ratchet mechanism 118. The archer will feel an
increase in the draw weight required to keep the primary cable 180
fully drawn, but the increase in draw weight should be well below
the composite peak draw weight of the bow 100. Effectively, the
archer is now holding the full peak draw weight of the bow 100;
however, because the cams 110, 112 associated with the primary
limbs 102, 104 are in let off, the archer will only be holding a
fractional amount of the peak draw weight determined by the let off
geometry of the cams. The UHMW tape 124-130 at the interface
surfaces of the primary and secondary sets of limbs 102-108 are now
in direct contact. The low coefficient of friction associated with
the tape reduces losses due to frictional effects, making the
conversion from potential energy stored in the limbs as strain
energy, to kinetic energy used to accelerate the arrow a more
efficient transition.
[0044] FIG. 1I shows the bow 100 after the primary cable 100 has
been released by the archer, accelerating the arrow downrange
toward the target. In this figure, the increased flexural rigidity
of the secondary limbs 106, 108 causes them to continue pushing
outwards against the primary limbs 102, 104. The cams associated
with the superior limbs 110, 114 and the cams associated with the
inferior limbs 112, 116 rotate in opposite directions. The ratchet
118 continues to rotate as it unspools more of the secondary cable
182. All of this happens very rapidly as the components of the bow
100 work in concert to accelerate the arrow. Once the arrow has
left contact with the primary cable 180 and the residual vibrations
throughout the system have ceased, the bow 100 is once again in the
equilibrium or release position (see FIG. 1A) and the complete
firing sequence as described herein may be repeated as
necessary.
[0045] FIG. 5A-5C depicts a various views of a compound bow 500
having a multi-stage draw. The bow 500 includes a riser 502, a
superior or upper limb 504, and an inferior or lower limb 506.
Proximate an end of the superior limb 504 is a superior cam 508 and
proximate an end of the inferior limb 506 is an inferior cam 510.
As common for compound bows, a cable 512 is connected at a first
end to a superior cam axle 514 and extends towards the inferior cam
510. The cable 512 is wrapped around a camming surface 516 of the
inferior cam 510 then extends towards the superior cam 508. After
wrapping around a camming surface 518 of the superior cam 508, the
cable 512 is connected to an inferior cam axle 520. The portion of
the cable 512 spanning the two camming surfaces 516, 518 may be
referred to as a bow string 522. This bow string 522 may be
integral with the cable 508 or comprise one or more of woven or
unwoven strings that are attached at either end to end portions of
two discrete cables. That is, one cable may be connected to the
superior camming axle 514 and wrapped around the inferior camming
surface 516 while another cable may be connected to the inferior
camming axle 520 and wrapped around the superior camming surface
518. The free ends of these two cables may be then connected to
ends of a discrete bow string 522. In certain embodiments, the two
cables may be a relatively stiff wire or other high strength
element, while the discrete cable string may be a more flexible
element.
[0046] The depicted bow 500 also includes a tensioning cable 524
connected at each end to the superior cam axle 514 and the interior
cam axle 520. The tensioning cable 524 is passed into a gearbox 526
via an upper opening 528 and a lower opening 530. The gearbox 526
may be secured to the riser 502 by an upper rod 532 and a lower rod
534. The rods 532, 534 need only extend from the riser 502 to the
gearbox 526, and the dimensions and/or profiles thereof are not
critical. Moreover, a single rod may be used. The depicted bow 500
utilizing two rods 532, 534, however, may help limit deflection.
The rods 532, 534 may be connected to the riser 502 via set screws
into riser 502, brackets or other mechanical elements, robust
chemical adhesives, or combinations thereof. In alternative
embodiments, risers may be manufactured from injection-molded
plastics, and the rods may be formed integrally therewith. It may
be desirable to reinforce such rods with internal support
structures to increase rigidity.
[0047] The tensioning cable 524 is used to deflect the limbs 504,
506 of the bow 500, as described below. Two guide elements 536, 538
are located proximate the openings 528, 530, respectively, on the
gearbox 526. The guide elements may be static elements, such as
expanding or otherwise shaped channels to guide the tensioning
cable 524 as it is drawn into and fed from the openings 528, 530.
In other embodiments, one or more rollers 540, 542 spanning the
raised portions of the guide elements 536, 538 may be used to
reduce friction. The gearbox 526 defines an opening 544 through
which a draw cable 546, ripcord, or other element may pass. The
draw cable 546 is used to actuate the gear system located within
the gearbox 526, as described below. The draw cable 546 extends
from the opening 544 so that it may be easily grasped by a user of
the bow 500.
[0048] FIG. 6 depicts a top view of the gearbox 526 with a top
cover removed, exposing a gear system 600. The gearbox 526 includes
an outer side wall 602, and an inner side wall 604. Here, the terms
"outer" and "inner" are used to identify the wall relative to the
location of the rods 532, 534. The gearbox 526 also includes a
proximal wall 606 and a distal wall 608 (relative to the user of
the bow 500). In brief and also referencing elements depicted in
FIGS. 5A-5C, the gear system 600 will allow the user to store
energy in the limbs 502, 504 by pulling on the draw cord 546. The
gear system 600 will reduce the required draw force by using a
number of gears and axles to create a mechanical advantage. A
standard draw cycle for the depicted gear system 600 will require
the user to pull the draw cord 546 twice to lock the limbs 502, 504
into a loaded or deflected position. Thereafter, the user may load
a projectile on the bow string 522 to fire the projectile. In
certain embodiments, the action of drawing the bow string 522 to a
firing or drawn position may release the gear system 600, enabling
the bow 500 to fire.
[0049] In the embodiment of FIG. 6, the gear system 600 includes
three gear sections 600a, 600b, and 600c, which are described in
more detail below. These three 600a, 600b, and 600c are also
depicted in FIGS. 7A-7C, where the various pulleys, gears, etc.,
are shown spaced apart from each other for clarity. Although any
spacing of these elements may be utilized, the elements are
generally spaced as depicted in FIG. 6. In reference to FIGS. 6 and
7A, a tensioning gear system 600a is shown and includes a
tensioning axle 610 supports a tensioning pulley 612, ratchet 614,
and a tensioning gear 616. The tensioning pulley 612 includes one
or more screw clamps, pins, or other securing elements 618 that are
used to secure the tensioning cable 524 to the tensioning pulley
612. As described above, the tensioning cable 524 passes through
the openings (lower opening 530 is depicted in FIG. 6), and is
wound partially around the tensioning pulley 612, supported in a
groove 620 located along an outer edge thereof. In the depicted
embodiment, the tensioning cable 524 is actually two cables
discrete from each other. A first end of each cable is attached to
either the superior axle 514 or the inferior axle 520. A second end
of each cable is secured to either of the securing elements 618a or
618b. As the tensioning axle 610 rotates during use, each of the
cables is guided into the circumferential groove 620. The
tensioning gear 616 is configured to interact with one of the gears
located on an intermediate axle 622.
[0050] Referring to FIGS. 6 and 7B, an intermediate gear section
600b is shown and includes the intermediate axle 622 that supports
a minor gear 624 and a major gear 626. The major gear interacts
with one of the gears on a draw cord axle 628. Referring to FIGS. 6
and 7C, a draw cord gear section 600c is shown and includes the
draw cord axle 630 that supports a draw cord gear 632 and a draw
cord pulley 634. The draw cord pulley 634 includes a screw clamp,
pin, or other securing element 636 that is used to secure the draw
cord 546 to the draw cord pulley 634. A spiral groove 638 provides
a guide for preventing the draw cord 546 from becoming entangled as
it wraps around an outer circumference of the draw cord pulley 634.
Additionally, the draw cord gear section 600c supports a clock
spring that biases the draw cord pulley 634 toward an initial
position. In the depicted embodiment, the clock spring is located
within the draw cord pulley 634 and is not shown. Additionally, two
linear springs located within spring housings 640 are configured to
bias the draw cable axle 630 toward the distal wall 608, such that
the draw cord gear 632 is not in engagement with the major gear 626
unless the draw cable 546 is being pulled toward the user. The
linear springs may be sized such that pulling the draw cable 546
first pulls the draw cord gear 632 into an engaging configuration
with the major gear 626, after which further pulling will rotate
the draw cord pulley 634.
[0051] Operation of the depicted bow 500 begins with the bow 500 in
a release position, where the bowstring 522 is positioned
substantially linearly between the cams 508, 510. The release
position is so named because this is the final position once an
arrow has been launched or released. This is also the initial
position of any bow prior to drawing the bow string to begin a
shooting action. As the draw cord pulley 634 is rotated by pulling
of the draw cord 546, the configuration of the gear system 600
compels rotation of the tensioning gear 616, which also rotates the
tensioning pulley 612. This draws the tensioning cable 524 (or
cables, as the case may be) around the tensioning pulley 612. This
movement deflects the limbs 504, 506 from an initial position (also
referred to as an equilibrium position) to a first deflected or
pre-loaded position. At the end of the first pull of the draw cord
546, a pawl located within the gearbox 526 engages a first tooth of
the ratchet 614. This locks the limbs 504, 506 in the first
deflected position. This position may be referred to as a hold
position for the bow 500. In the hold position, the bow 500 is
unable to launch a projectile because the bow 500 is prevented from
returning to the release position directly from the hold position,
due to the interaction between the pawl and the ratchet 614. The
clock spring then returns the draw cable pulley 634 to the initial
position. A second pull of the draw cable 546 draws the limbs 504,
506 closer together, into a second deflected position. This second
deflected position of the limbs 504, 506 may be referred to as a
second hold position for the bow 500. The pawl engages a second
tooth of the ratchet 614 and the clock spring again returns the
draw cable pulley 634 to the initial position. This process of
drawing the limbs 504, 506 into further deflected positions may
continue as required or desired, until the maximum deflected
position of the limbs 504, 506 is attained. In the depicted
embodiment, however, only two draws to first and second bow hold
positions are required.
[0052] At this point, a projectile such as an arrow may be knocked
or secured to the bow string 522. To complete operation, the user
first must draw the bow string 522 towards the user, as typical for
use of a bow. To launch the arrow, the pawl first must be
disengaged from the ratchet 614. This may be accomplished in a
number of ways. In one embodiment, the draw of the bow to a ready
or charged position will release the pawl, thus enabling launching
of the arrow. In such an embodiment, the final draw of the bow
string 522 will release tension from the tensioning cable 524 thus
allowing the pawl to return to a disengaged position. In another
embodiment, an electronic actuator located on the riser 502 may be
actuated by, for example, the thumb of the user. The actuator may
send a signal that actuates an electro-mechanical mechanism to move
the pawl away from the ratchet 614. Additionally, the user may
actuate a mechanical trigger connected by a cable or other linking
element to the pawl. The ready position may be defined as the
position from which the projectile may be launched, or the
bowstring released in a controlled manner (and the projectile
retained thereon). In either case, the depicted embodiment allows
for movement of the bow to the release position only once the ready
position is reached. In the ready position, the user will not hold
a significant weight because the last portion of the draw will
occur when the curvature of the cams 508, 510 are in the "let off"
position, therefore the draw weight in this position will be
greatly reduced. The "let-off" position refers to the point in a
bow draw cycle when the cam lobes rotate to give a mechanical
advantage to the user. At this point, much less force is required
to keep the bow drawn. This will allow the average user to create
the same energy as a standard compound bow while reducing the draw
weight. The bow 500 may then be aimed and fired normally.
[0053] The gears used in the gear system 600 may be selected as
desired or required for a particular application to obtain the
desired gear ratios. In one embodiment, the gear system will
produce an 8:1 mechanical advantage which will allow half the
normal draw force while producing a similar energy output of a
comparable unmodified bow system. Other ratios are contemplated. By
the reducing the draw weight by half, the effective draw length
must be doubled to produce a similar energy output. The reduced
draw weight will allow people of limited upper body strength and
others with limiting disabilities improved performance. In other
embodiments, multiple pulleys may be used in conjunction with a
clutch, ratchet, or other mechanism for holding the tensioning
cable subsequent to each pull of a pulley string. The pulleys may
be sized accordingly to provide the desired mechanical advantage
when using the bow.
[0054] The technologies described herein are described in the
context of handheld compound bows. However, a person of skill in
the art will recognize the applicability of the disclosed
technologies into other projectile-launching implements, for
example, crossbows (compound or otherwise), ballistae, etc.
Additionally, certain of the technologies, especially the gearbox
configuration of FIGS. 5A-7C may be utilized in non-cammed bows,
such as longbows, recurve bows, and composite bows.
[0055] While there have been described herein what are to be
considered exemplary and preferred embodiments of the present
technology, other modifications of the technology will become
apparent to those skilled in the art from the teachings herein. The
particular methods of manufacture and geometries disclosed herein
are exemplary in nature and are not to be considered limiting. It
is therefore desired to be secured in the appended claims all such
modifications as fall within the spirit and scope of the
technology. Accordingly, what is desired to be secured by Letters
Patent is the technology as defined and differentiated in the
following claims, and all equivalents.
* * * * *