U.S. patent application number 14/828047 was filed with the patent office on 2015-12-10 for elastic projectile propulsion systems and methods.
This patent application is currently assigned to SERPENT RURAL SPORTS LLC. The applicant listed for this patent is SERPENT RURAL SPORTS LLC. Invention is credited to JAMES T. BOND, JONATHAN C. POLANICH.
Application Number | 20150354916 14/828047 |
Document ID | / |
Family ID | 52484075 |
Filed Date | 2015-12-10 |
United States Patent
Application |
20150354916 |
Kind Code |
A1 |
POLANICH; JONATHAN C. ; et
al. |
December 10, 2015 |
ELASTIC PROJECTILE PROPULSION SYSTEMS AND METHODS
Abstract
An elastic projectile propulsion system deploys a plurality of
springs that bias a common launching cord via a plurality of block
and tackle pulleys. Each sheave of the pulley is coupled to the
moveable end of a spring such that the force of each spring
contributes to the energy imparted to a projectile by the launching
cord without adding significant friction or inertial
resistance.
Inventors: |
POLANICH; JONATHAN C.; (LOS
GATOS, CA) ; BOND; JAMES T.; (SANTA ROSA,
CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SERPENT RURAL SPORTS LLC |
LOS GATOS |
CA |
US |
|
|
Assignee: |
SERPENT RURAL SPORTS LLC
LOS GATOS
CA
|
Family ID: |
52484075 |
Appl. No.: |
14/828047 |
Filed: |
August 17, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14654760 |
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PCT/US14/51440 |
Aug 18, 2014 |
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14828047 |
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61867383 |
Aug 19, 2013 |
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61946736 |
Mar 1, 2014 |
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Current U.S.
Class: |
124/25.6 |
Current CPC
Class: |
F41B 7/003 20130101;
F41B 7/04 20130101; F41B 5/0094 20130101; F41B 7/00 20130101 |
International
Class: |
F41B 7/00 20060101
F41B007/00 |
Claims
1. A propulsion device, comprising: a forward spring member having
a forward spring member proximal end and a forward spring member
distal end, wherein the distal end of the forward spring member
connects to a first brace and the proximal end of the forward
spring member connects to a distal moveable pulley block, a
rearward spring member having a rearward spring member proximal end
and a rearward spring member distal end, wherein the distal end of
the rearward spring member connects to a proximal moveable pulley
block and the proximal end of the rearward spring member connects
to a second brace, at least one forward pulley coupled to the
forward spring member proximal end and at least one rearward pulley
connected to the rearward spring member distal end, and a launching
cord engaging the forward pulley and the rearward pulley.
2. The propulsion system of claim 1, wherein the at least one
forward pulley and the at least one rearward pulley comprise a
counteracting block and tackle pulley assembly which couples an
elastic energy stored in the forward spring member and the rearward
spring member when the launch cord is drawn rearward.
3. The propulsion device of claim 1, further comprising a rail with
a distal fixed brace at a distal end thereof and a proximal fixed
brace at a proximal end thereof, the distal fixed brace supporting
the first moveable brace and the proximal fixed brace supporting
the second moveable brace.
4. The propulsion device of claim 3, wherein the rail is
configurable to vertically move while remaining stationary
horizontally.
5. The propulsion device of claim 1, further comprising a cocking
mechanism.
6. The propulsion device of claim 1, wherein the propulsion device
has a width of 12 inches or less.
7. The propulsion device of claim 1, further comprising a trigger
assembly.
8. The propulsion device of claim 1, wherein the at least one
forward pulley comprises a first forward pulley, the device further
comprising a second forward pulley.
9. The propulsion device of claim 1, wherein the forward spring
member comprises a first forward spring member and the rearward
spring member comprises a first rearward spring member, the device
further comprising: a second forward spring member; and a second
rearward spring member.
10. The propulsion device of claim 9, wherein the first and second
forward spring members and the first and second rearward spring
members are combined in parallel banks, wherein a first one of the
parallel banks engages the first moveable pulley block and a second
one of the parallel banks engages the second movable pulley
block.
11. A propulsion device for propelling a projectile therefrom,
comprising: an elongated member having a proximal fixed base and a
distal fixed base; a forward spring member attached at a distal end
thereof to the distal fixed base; a distal moveable pulley block
attached to a proximal end of the forward spring member; at least a
first and second distal pulley spaced apart and disposed on the
distal moveable pulley block; a rearward spring member attached at
a proximal end thereof to the proximal fixed base; a proximal
moveable pulley block attached to a distal end of the rearward
spring member; at least one proximal pulley disposed on the
proximal moveable pulley block; and a launching cord spanning
between the at least one proximal pulley and the first and second
distal pulleys.
12. The propulsion device of claim 11, wherein the launching cord
is attached at a first end to the proximal moveable pulley block
and extends about the first distal pulley, returns to the at least
one proximal pulley, extends back to the first distal pulley,
continues to the second distal pulley, extends to the at least one
proximal pulley, back to the second distal pulley, and terminates
at a second end attached to the proximal moveable pulley block.
13. The propulsion device of claim 12, wherein at least one of the
first end and the second end of the launching cord is attached to
an adjustment mechanism to adjust a length of the launching
cord.
14. The propulsion device of claim 11, wherein a launch cord center
is disposed between the first and second distal pulleys, wherein
the launch cord center is configured to receive a portion of one
end of the projectile, wherein the launch cord center is moved
proximally to achieve a cocked configuration.
15. The propulsion device of claim 11, further comprising a passive
safety mechanism configured to prevent unintentional discharge of
the projectile when the propulsion system is in a cocked
configuration.
16. The propulsion device of claim 11, further comprising: a distal
moveable brace interconnecting a distal end of the forward spring
with the distal fixed brace, the distal moveable brace permitting
movement between the distal end of the forward spring and the
distal fixed brace; and a proximal moveable brace interconnecting a
proximal end of the rearward spring with the proximal fixed brace,
the proximal moveable brace permitting movement between the
proximal end of the rearward spring and the proximal fixed
brace.
17. The propulsion device of claim 11, further comprising an
adjustable over-molded center rail configured to support the
projectile, the adjustable over-molded center rail running along a
length of the rail and being adjustable to adjust the position of
the projectile relative to the rail.
18. The propulsion device of claim 11, further comprising a
launching cord catch operable to secure the launching cord in a
cocked configuration when the projectile is absent, thereby
preventing dry-firing of the propulsion system.
19. The propulsion device of claim 11, further comprising a foot
claw resiliently extendable from the distal end of the rail.
20. A propulsion device, comprising: a rail comprising a proximal
fixed base and a distal fixed base; a forward spring member
attached at a distal end thereof to the distal fixed base; a distal
moveable pulley block attached to a proximal end of the forward
spring member; at least a first and second distal pulley spaced
apart and disposed on the distal moveable pulley block; at rearward
spring member attached at a proximal end thereof to the proximal
fixed base; a proximal moveable pulley block attached to a distal
end of the rearward spring member; at least one proximal pulley
disposed on the proximal moveable pulley block; and a launching
cord spanning between the at least one proximal pulley and the
first and second distal pulleys, wherein when the launching cord is
pulled proximally from a launching cord center region formed
between the first and second distal pulleys, a first force is
exerted on the distal moveable pulley block by the forward spring
member and a second force is exerted on the proximal moveable
pulley block by the rearward spring member; and a quantity of the
proximal pulleys, a quantity of the distal pulleys, a configuration
of the launching cord, and a spring constant of the rearward and
forward spring members are chosen to substantially balance the
first force and the second force.
21. The propulsion device of claim 20, wherein the launching cord
is attached at the first end to the proximal moveable pulley block
and extends about the first distal pulley, returns to the at least
one proximal pulley, extends back to the first distal pulley,
continues to the second distal pulley, extends to the at least one
proximal pulley, back to the second distal pulley, and terminates
at the second end attached to the proximal moveable pulley
block.
22. The propulsion device of claim 20, wherein: the forward spring
includes at least one set of forward springs, the at least one set
including a first forward spring and a second forward spring, the
first and second forward springs being disposed on opposite sides
of the rail; and the rearward spring includes at least one set of
rearward springs, the at least one set including a first rearward
spring and a second rearward spring, the first and second rearward
springs being disposed on opposite sides of the rail.
Description
CROSS-REFERENCE
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/867,383, entitled ELASTIC PROJECTILE PROPULSION
SYSTEM, filed on Aug. 19, 2013, and 61/946,736, entitled ELASTIC
PROJECTIVE PROPULSION SYSTEM, filed Mar. 1, 2014, which
applications are incorporated herein by reference.
BACKGROUND
[0002] The present disclosure relates to a compact propulsion
systems that deploys stored elastic energy to propel a projectile,
and more particularly to a compact propulsion system for launching
an arrow and other flying projectiles.
[0003] Prior methods of launching arrows and other projectiles have
deployed elastic energy stored in springs, such as leaf springs in
a bow, torsion springs and coil springs, rubber tubes and bands, as
well as the elastic energy stored in a stretched launching cord.
Various combinations of these elements are known, some of which
include a series of pulleys to extend and direct the launching cord
in a generally serpentine path. See, for example, U.S. Pat. No.
2,515,205 A to Fieux for Catapult Device for Launching Aerial
Machines, issued Jul. 18, 1950.
[0004] However, the prior systems have limitations. While metal
springs are more reliable over a range of temperatures than rubber
springs, the higher mass of the metal springs imposes a velocity
limitation.
[0005] Bow systems are not compact (typically having a width of at
least 12 inches (30.48 centimeters) or more at a widest point), and
require large loading force (crossbows typically having 125-200 lbs
(56.7-90.72 kilograms) of draw weight), which is overcome by adding
heavy, bulky and complicated levers and ratchets, thereby
increasing size and weight of the device.
[0006] Additionally, bow systems are limited in the ability to
reabsorb stored energy without sustaining damage to the bow during
launch. Hence, bow systems require a minimum arrow weight be
matched proportionately to a draw force of a bow in order to
dissipate energy away from the bow during launch and ensure
functionality without incurring damage to the bow system. Widely
adopted industry standards recommend that a bow never be deployed
to launch without an arrow ("dry fired") and have set a minimum
ratio of arrow weight to draw force which, in turn, imposes a
velocity limitation.
[0007] The devices disclosed herein provide a propulsion
configuration that can overcome the above limitations.
SUMMARY
[0008] An aspect of the disclosure provides a propulsion device
comprising a rigid elongated barrel member having a forward
(distal) launching end and an opposing (proximal) stock connecting
end, a pair of forward (distal) spring members each mounted to
connect at a distal end thereof on opposing sides of the barrel
adjacent the forward (distal) launching end, each forward (distal)
spring having a distal end connected to the barrel opposite the
moveable proximal end, a pair of rear (proximal) spring members,
each mounted to connect to the barrel at a proximal end thereof on
opposite sides of the barrel adjacent the proximal stock end, a
pair of moveable fore pulley blocks, each coupled to the proximal
moveable end of each forward spring member and at least one
proximal moveable pulley block, connected to the distal moveable
end of each rear spring member, a launching cord having each of the
opposing ends and engaging both the distal and proximal moveable
pulley blocks on opposing sides of the barrel to provide a pair of
moveable, counter acting block and tackle pulleys to couple the
elastic energy stored in the distal and proximal spring members
when a launch cord center is drawn in a proximal direction toward
the stock connecting end of the barrel. Components made from
elastic materials are resilient and enable the component to spring
back into a predetermined shape after a deforming force is
removed.
[0009] A second aspect of the disclosure provides a method of
propelling a projectile, such as an arrow. The method comprises the
steps of providing a propulsion device, providing a projectile
having a forward (distal) end and a rear (proximal) end opposite
the forward end, resting the projectile on a barrel to engage a
center of a launching cord at the rear (proximal) end of the
projectile, drawing the center of the cord and attached projectile
in the rearward (proximal) direction to tension the launching cords
engaged in the adjacent moveable pulley blocks attached to the
distal and proximal spring members on both opposing sides of the
barrel and in turn extend each of the distal and proximal spring
members toward the other, releasing the launching cord and
projectile to provide a mutual and simultaneous transfer of energy
from the tensioned springs and launching cord to the projectile.
Alternatively, the linear projectile, such as an arrow, may be
secured within the device after the launch cord has been fully
tensioned, and thereafter, the user releases the draw on the
projectile (e.g., by pulling the trigger, releasing the launch
cord, etc.), which causes a transfer of energy from the tensioned
springs and launch cord to the projectile.
[0010] An aspect of the disclosure is directed to propulsion
devices. Suitable propulsion devices, comprise: a) an elongated
barrel member forming a cavity having an elongated barrel member
proximal end and an elongated barrel member distal end, where the
elongated barrel member proximal end engages a mounting stock, b) a
pair of forward spring members each having a forward spring member
proximal end and a forward spring member distal end, the pair of
forward spring members positioned within the cavity of the
elongated barrel member wherein the distal ends of the forward
spring members connect to a corresponding moveable brace and the
proximal ends of the forward spring members connect to a moveable
pulley blocks, c) a pair of rearward spring members, each having a
rearward spring member proximal end and a rearward spring member
distal end, the pair of rearward spring members positioned within
the cavity of the elongated barrel member wherein the distal end of
the rearward spring members connects to the moveable pulley blocks
and the proximal ends of the rearward spring members connects to
the corresponding moveable braces, d) at least one pair of forward
pulleys, each forward pulley coupled to the forward spring member
proximal ends and at least one rearward pulley, connected to each
of the rearward spring member distal ends, and e) a launching cord
having a first end and a second end which can attach at either the
forward moveable pulley blocks or the rearward moveable pulley
blocks and traverse a serpentine path around pulleys to engage both
the forward pulleys and rearward pulleys. In at least some
configurations, the pair of forward pulleys and the rearward pulley
are configurable to comprise a counteracting block and tackle
pulley which couples an elastic energy stored in the forward spring
members and the rearward spring members when the launch cord is
drawn rearward toward the stock connecting end of the barrel.
Additionally, a rail can be provided and interiorly positioned in
the barrel member. The rail can also be configurable to vertically
move while remaining stationary horizontally. Additionally, a
cocking mechanism and/or trigger assembly can be provided.
Propulsion devices are configurable such that they have a width of
12 inches or less. In some configurations, the launching cord is
wrapped three or more times around the distal pulley. Additionally,
the forward spring members and the rearward spring members are
combined in parallel banks, wherein each bank engages one or more
moveably pulley blocks.
[0011] Another aspect of the disclosure is directed to linear
archery systems. The linear archery systems comprise: a) an
elongated barrel member forming a cavity having an elongated barrel
member proximal end and an elongated barrel member distal end,
where the elongated barrel member proximal end engages a mounting
stock, b) one or more of a forward spring member each of the one or
more forward spring members having a forward spring member proximal
end and a forward spring member distal end, the one or more forward
spring members positioned within the cavity of the elongated barrel
member wherein the distal end of the one or more forward spring
members connects to a moveable brace and the proximal ends of the
forward spring members connect to a moveable pulley block, c) one
or more rearward spring members, each of the one or more rearward
spring members having a rearward spring member proximal end and a
rearward spring member distal end, the one or more rearward spring
members positioned within the cavity of the elongated barrel member
wherein the distal end of the one or more rearward spring members
connects to the moveable pulley blocks and the proximal ends of the
rearward spring members connects to the corresponding moveable
brace, d) one or more forward pulleys, each of the one or more
forward pulleys coupled to at least one of the one or more forward
spring member proximal ends and at least one rearward pulley,
connected to the rearward spring member distal end, and e) a
launching cord having a first end and a second end which can attach
at either the forward moveable pulley blocks or the rearward
moveable pulley blocks and traverse a serpentine path around
pulleys to engage both the forward pulleys and rearward pulleys. In
at least some configurations, the pair of forward pulleys and the
rearward pulley are configurable to comprise a counteracting block
and tackle pulley which couples an elastic energy stored in the
forward spring members and the rearward spring members when the
launch cord is drawn rearward toward the stock connecting end of
the barrel. Additionally, a rail can be provided that is interiorly
positioned in the barrel member. The rail is also configurable to
vertically move while remaining stationary horizontally.
Additionally, a cocking mechanism and/or trigger assembly can be
provided. Configurations of the systems have a width of 12 inches
or less. Additionally, the launching cord is wrapped three or more
times around the distal pulley.
[0012] Still another aspect of the disclosure is directed to
self-arresting propulsion systems. The self-arresting propulsion
systems comprise: a) an elongated barrel member forming a cavity
having an elongated barrel member proximal end and an elongated
barrel member distal end, where the elongated barrel member
proximal end engages a mounting stock, b) a pair of forward spring
members each having a forward spring member proximal end and a
forward spring member distal end, the pair of forward spring
members positioned within the cavity of the elongated barrel member
wherein the distal end of the forward spring members connect to a
corresponding moveable brace and the proximal ends of the forward
spring members connect to a moveable pulley block, c) a pair of
rearward spring members, each having a rearward spring member
proximal end and a rearward spring member distal end, the pair of
rearward spring members positioned within the cavity of the
elongated barrel member wherein the distal end of the rearward
spring members connect to the moveable pulley block and the
proximal end of the rearward spring members connects to the
corresponding moveable brace, d) a pair of forward pulleys, each
forward pulley coupled to one of the forward spring member proximal
ends and at least one rearward pulley, connected to the rear ward
spring member distal end, and e) a launching cord having a first
end and a second end which can attach at either the forward
moveable pulley blocks or the rearward moveable pulley blocks and
traverse a serpentine path around pulleys to engage both the
forward pulleys and rearward pulleys, wherein the pair of forward
pulleys and the rearward pulley comprise a counteracting block and
tackle pulley which couples an elastic energy stored in the forward
spring members and the rearward spring members when the launch cord
is drawn rearward toward the stock connecting end of the barrel.
Additionally, a rail interiorly positioned in the barrel member can
be provided. The rail can be configurable to vertically move while
remaining stationary horizontally. Some configurations will include
a cocking mechanism and/or trigger assembly. As with other
configurations, the systems have a width of 12 inches or less. The
launching cord is wrapped three or more times around the distal
pulley.
[0013] Yet another aspect of the disclosure is directed to methods
of operating a system according to any of the configurations
disclosed. The methods comprise the steps of: providing a
propulsion device, drawing the launching cord in the rearward
direction to tension the launching cord and extend each of the
forward spring member and rearward spring members towards each
other, and releasing the launching cord to provide a mutual and
simultaneous transfer of energy from the tensioned springs and
launching cord. Additionally, the method can include providing a
linear projectile, and placing the linear projectile in the barrel
of the propulsion system to engage the launching cord, wherein the
steps of providing the linear projectile and placing the linear
projectile in the barrel of the propulsion system is performed
after the step of drawing the launching cord.
INCORPORATION BY REFERENCE
[0014] All publications, patents, and patent applications mentioned
in this specification are herein incorporated by reference to the
same extent as if each individual publication, patent, or patent
application was specifically and individually indicated to be
incorporated by reference, for all purposes and as if repeated in
total in the present application. Additional references of interest
include U.S. Pat. No. 4,050,438A to Pfotenhauer issued Sep. 27,
1977 for SPRING TYPE PROJECTING DEVICE; U.S. Pat. No. 4,169,456A to
Van House issued Oct. 2, 1979 for SHORT LIMB ARCHERY BOW; U.S. Pat.
No. 4,411,248A to Kiveson issued Oct. 25, 1983 for CATAPULT
CONSTRUCTION; U.S. Pat. No. 4,703,744A to Taylor et al. issued Nov.
3, 1987 for APPARATUS FOR SHOOTING A PROJECTILE; U.S. Pat. No.
5,243,955A to Farless issued Sep. 14, 1993 for MECHANICAL SHOOTING
APPARATUS; U.S. Pat. No. 5,673,677A to Wing issued Oct. 7, 1997,
for PROJECTILE LAUNCHING APPARATUS; U.S. Pat. No. 7,578,289B2 to
Norkus issued Aug. 25, 2009 for COMPOUND ARCHERY BOW WITH EXTENDED
INVERTED STROKE; and PCT Publication WO2012/150387A1 to Lamine
published Nov. 8, 2012 for SPEARGUN FOR UNDERWATER FISHING.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The novel features of the invention are set forth with
particularity in the appended claims. A better understanding of the
features and advantages of the present invention will be obtained
by reference to the following detailed description that sets forth
illustrative embodiments, in which the principles of the invention
are utilized, and the accompanying drawings of which:
[0016] FIG. 1A is a top plan view of a propulsion system which
includes an outer frame, and FIG. 1B is the same view omitting the
outer frame, whereas, FIG. 1C is a side elevation view including
the outer frame, and FIG. 1D is the same view as FIG. 1C again
omitting the outer frame;
[0017] FIG. 2 is a perspective view of the launching cord as it is
wrapped between the distal and proximal pulleys within their
respective moveable pulley blocks but without the distal moveable
pulley blocks;
[0018] FIG. 3A is side elevation view of the device in a retracted
spring position, whereas FIG. 3B is a side elevation view in an
extended spring position or projectile launch ready state; FIG. 3C
is a close-up side view of the sliding trigger assembly including
the outer frame; FIG. 3D is a close-up front cross-sectional view
of the sliding trigger assembly including the outer frame;
[0019] FIG. 4 is perspective partial view of the springs in the
extended position or projectile launch ready state;
[0020] FIG. 5 is a more detailed perspective view of the moveable
pulley mechanism attached to the springs in the extended position
or projectile launch ready state;
[0021] FIG. 6 is a partial enlarged perspective view of FIG. 4 and
FIG. 5 that includes the nock of arrow projectile, adjacent the
distal moveable pulleys attached to the springs in the retracted
position;
[0022] FIG. 7A is an top plan view of the outer frame as it
connects to the fixed braces, shown in the extended spring position
or projectile launch ready state, whereas
[0023] FIG. 7B depicts the top plan view with the outer frame
omitted to better depict the fixed and moveable brace connections
to the springs in the extended position, and
[0024] FIG. 7C illustrates the top plan view with the outer frame
omitted to better depict the fixed and moveable brace connections
with springs in a position during retraction, and
[0025] FIG. 7D illustrates the top plan view with the outer frame
omitted to better depict the springs in the retracted position;
[0026] FIGS. 8A-C are schematic diagrams of the cord, pulley
blocks, pulleys and springs representing alternative configurations
tested in comparative examples;
[0027] FIGS. 9A-H are isolated views of rail mechanisms, such as
shown in FIGS. 1 and 7;
[0028] FIGS. 10A-C are front and isometric views that depict the
positions of the grip as configured in an integrated cocking
mechanism;
[0029] FIGS. 11A-F are partial side and top views of the passive
safety mechanism;
[0030] FIGS. 12A-H are partial side and top views detailing the
anti-dry-fire mechanism;
[0031] FIGS. 13A-D are side and isometric views illustrating the
auto-retractable foot claw mechanism;
[0032] FIGS. 14 A-C illustrate the adjustable stock; wherein FIGS.
14A-B are partial side views detailing the full range
adjustability, and FIG. 14C is a detailed proximal view of the
components of the stock release mechanism;
[0033] FIGS. 15A-B are isometric, close-up, views of launch cord
tensioning terminals; and
[0034] FIGS. 16A-B are top views of an arrow retaining system with
springs extended and arrow loaded, and springs retracted arrow
unloaded.
DETAILED DESCRIPTION
[0035] Referring to FIGS. 1 through 16, wherein like reference
numerals refer to like components in the various views, there is
illustrated therein a new and improved device for an elastic
projectile propulsion system, generally denominated 100 herein. The
elastic projectile propulsion system is a linear archery system.
The elastic projectile propulsion system 100 can be described as a
launching device or launcher. Spatial orientation references
`proximal` and `distal` have been labeled in the figures as "P" and
"D", respectively, where proximal is situated nearest the user and
distal is situated furthest from the user. The systems and devices
position the launch cord between moveable pulleys.
[0036] The various described embodiments described herein provide
multiple benefits, which include for example, stable elastic metal
or composite springs which are deployable with a reduced inertial
burden imposed by the spring mass on the velocity of the projectile
such as an arrow, as the elastic projectile propulsion system 100
couples the force and travel distance of multiple springs utilizing
moveable pulleys and an attached launch cord to simultaneously
accelerate the launch cord and attached projectile at a velocity
that exceeds the velocity of each individual spring moving
simultaneously within the system. In addition, the elastic
projectile propulsion system 100, which is a launching device, can
be very narrow (e.g. 12 inches (30.48 centimeters) or less in
width), light-weight (e.g., 9 pounds (4.08 kg) or less in weight),
compact (e.g., having a volume of 500 cubic inches (8,193 cubic
centimeters), or less). As an example of this benefit, in the
comparison to competitive shooting crossbows, a high velocity arrow
flight is achieved without a bulky, wide and heavy bow limbs. As
well, the stable metal or composite springs within the elastic
propulsion system 100 provide more reliable elastic performance
under a range of temperate weather conditions compared to
propulsion devices utilizing rubber elasticity, which is known to
have elastic performance that varies with a wide range of temperate
weather conditions.
[0037] Additionally, the embodiments described provide for a
self-arresting propulsion system which allows the safe use of
lighter weight arrows than usable in currently available bows and
crossbows, which generally follow industry guidelines that limit
arrow weight to 5 grains of arrow weight per pound of bow draw
force. As will be appreciated by those skilled in the art, lighter
arrows can attain much higher velocities than heavier arrows when
launched at the same draw length and force (e.g., power stroke).
The propulsion system 100 is capable of safely launching
projectiles such as arrows that are less than 5 grains of arrow
weight per pound of draw force. Still another advantage to the
configurations provided herein is that there is very low draw
weight, which is less than 125 lbs. This enables the user to
directly cock the device and does not require a cocking device
employing significant mechanical advantage. As will be appreciated
by those skilled in the art, most crossbows range from 125-200 lbs
(56.7-90.72 kilograms) of draw weight and require a cocking assist
either as a separate device or as an integrated component in order
to gain a mechanical advantage.
Devices and Systems
[0038] Turning now to FIG. 1A, a top plan view of an elastic
projectile propulsion system 100 is illustrated which includes an
elongated outer frame 111, where the length is greater than the
width. FIG. 1B is the same view of an elastic projectile propulsion
system 100 omitting the outer frame. FIG. 1C is a side elevation
view of the elastic projectile propulsion system 100 including the
elongated outer frame 111. FIG. 1D is the side elevation of the
elastic projectile propulsion system 100 omitting the outer frame.
In accordance with the present disclosure, the elastic projectile
propulsion system 100 has an elongated outer frame 111 having a
cavity therein with an interior surface and an exterior surface, an
elongated center rail member 110 having a distally positioned
forward launching end 110a and a proximally positioned opposing
stock connecting end 110b. Elongated center rail member 110 is
configurable to connect to a portion of the interior surface of the
elongated outer frame 111, along a length of a bottom of the inner
wall of the elongated outer frame 111. The connection between the
elongated outer frame 111 and the elongated center rail member 110
can be in a stationary position, as illustrated in FIG. 1A and FIG.
1C. One or more fixed braces 220, 230 can be provided to connect to
the elongated outer frame 111 on the interior surface and
perpendicular to the inner walls of elongated outer frame 111, each
of the fixed braces 220, 230 are positionable at opposing ends of
the elongated outer frame 111, e.g. at a proximal position and a
distal position in a stationary position, as illustrated in FIGS.
1A-D.
[0039] Elongated center rail member 110 and fixed braces 220, 230
can be formed integrally with elongated outer frame 111 in a fixed
position to form a rigid and robust barrel structure or housing. A
pair of forward spring members 120, 120' positioned distally, are
mountable to connect to a fixed brace 220 via moveable braces 127a,
127'a at a distal spring end 120a, 120'a thereof on opposing sides
of the elongated center rail member 110 adjacent a distally
positioned forward launching end 110a, each of the forward spring
members 120, 120' having a proximal spring ends 120b, 120'b
opposite the distal spring ends 120a, 120'a. Likewise, a pair of
rear spring members 130, 130' positioned proximally, are mountable
to connect to fixed brace 230 via moveable brace 137a, 137'a at
proximal spring ends 130a, 130'a thereof on opposite sides of the
elongated center rail member 110 adjacent the proximally positioned
opposing mounting stock 160 connecting end 110b, with distal spring
ends 130b, 130'b opposite the proximal spring ends 130a, 130'a.
Each of the forward spring members 120, 120' and the rear spring
members 130, 130' is connectable to a member of a moveable pulley
block or block and tackle system 140 (shown in more detail in FIG.
2, FIG. 5, FIG. 6 and FIGS. 15A-B) that deploys the proximal
moveable pulley blocks 135, 135' and distal moveable pulley blocks
125, 125', and that includes a launch cord 150. It should be noted
that distal moveable pulley blocks 125, 125' are comprised of top
moveable pulley block linkages 125a, 125'a and the lower linkage
portion of moveable brackets 127b, 127'b and are connected to hold
the pulley wheels 126a, 126b, 126'a, 126'b via pulley wheel axels
129, 129', as illustrated in FIG. 6. In addition, moveable pulley
blocks 135, 135' are comprised of top moveable pulley block linkage
135a,135'a and bottom moveable pulley block linkages 135b, 135'b
and are connected to hold the pulley wheels via pulley wheel axels
139, 139' as illustrated in FIG. 15A-B.
[0040] For a handheld device, as shown in FIG. 1D, it is also
preferable to deploy a hand grip 161 or support or mounting stock
160 at the proximal end of the elongated center rail member 110.
While the device may be configured to extend and release the launch
cord 150 directly by hand, a launch cord release latch 170 can also
be used which is activated by trigger 180 which is connected to
elongated center rail /10 via trigger assembly 185. Further, the
diameter of the distal moveable pulley blocks 125, 125', and the
proximal moveable pulley blocks 135, 135' is no wider that the
forward spring members 120, 120' and rear spring members 130, 130'
to keep the elastic projectile propulsion system 100 compact (e.g.,
having a diameter from 1/4 inch to 3/4 inch). Pulleys or sheaves,
which are a grooved wheel as part of a pulley block can include
bearings, not shown, to reduce friction, or be provided without
bearings.
[0041] FIG. 2 is a perspective view of the launch cord 150 as it is
wrapped between the distal pulleys and the proximal pulleys within
their respective moveable pulley blocks (without illustrating the
distal moveable pulley blocks). As illustrated at least one
proximal pulley 136, 136' is connected or coupled via proximal
moveable pulley blocks 135, 135' to a distal spring end of each
rear spring members via moveable braces 137b, 137'b and at least
one distal pulley 126a, 126b and 126'a, 126'b is coupled or
connected to the proximal spring end via distal moveable pulley
blocks of each of the forward spring members (distally positioned).
A launch cord 150 has a launch cord first end 150a and a launch
cord second end 150b (opposing launch cord ends) engaging both the
proximal moveable pulleys 136, 136' within blocks 135, 135' and the
distal pulleys 126a, 126b and 126'a, 126'b within their respective
moveable pulley blocks (not pictured) and on opposing ends of the
tackle system to provide a pair of counter acting block and tackle
pulleys to couple the elastic energy stored in the forward spring
members and rear spring members, when a launch cord center 150c is
drawn rearward (proximal).
[0042] Coupling each moveable pulley block and an associated
pulley(s) to move with a spring overcomes an inertial burden of
metal springs by adding a force of multiple cooperating springs
without excess friction. Moreover, it is preferable to provide
three wraps of a launch cord 150 between distal pulleys 126a, 126b,
and proximal pulley 136 and three wraps of launch cord 150 between
proximal pulley 126'a, 126'b and proximal pulley 136', as
illustrated in FIG. 2 (which omits the springs that are attached to
each moveable pulley block). The springs and pulleys of this
configuration arc also shown schematically in FIG. 8C.
[0043] The combination of multiple launch cord wraps between
pulleys that move in cooperation with the springs on release of the
launch cord and the projectile enables a large launch velocity by
simultaneously improving the speed at which the force of the launch
stroke is transferred to the projectile and facilitates a compact,
light-weight, robust and reliable design. First, it should be
understood that the launch velocity will be proportional to the
product of the launching force and launch stroke, which is the
distance over which the force is applied. Second, it should now be
understood that the velocity will also be proportional to the speed
at which the launching force can be applied. However, coil springs
have not been favored for archery propulsion by those skilled in
the art because coil springs have been at a compromise between
these factors, as increasing the launch force and or stroke through
larger or more powerful springs is limited by proportional increase
in spring mass and inertia. Although elastomers or rubber materials
provide a high energy to mass density, the materials are not
reliable below 40.degree. F. (4.4 degree Celsius). Further, the
materials can degrade or crack from repeated use and environmental
exposure, and are subject to physical damage from other materials
they may contact. Metal and composite coil springs are generally
more reliable than elastomers or rubber materials when used in
these conditions.
[0044] FIG. 3A is side elevation view of the device in a retracted
spring position, whereas FIG. 3B is a side elevation view in an
extended spring position or projectile launch ready state. FIG. 3C
is a close-up side view of the sliding trigger assembly including
the outer frame and FIG. 3D is a close-up front cross-sectional
view of the sliding trigger assembly including the outer frame.
When the projectile 10, such as an arrow, is launched the distal
moveable pulley blocks 125, 125' connected to moveable braces 127b,
127'b arc pulled in a distal direction via forward spring members
120, 120' and the proximal moveable pulley blocks 135, 135'
connected to moveable braces 137b, 137'b are pulled in a proximal
direction via rear spring members 130, 130'. Thus, as shown in FIG.
3A in the retracted spring position the distal moveable pulley
blocks 125, 125'are separated from the moveable pulley blocks 135,
135' by a distance, first distance L1, which upon loading or
extending as shown in FIG. 3B, decreases from the first distance L1
to a lesser distance, second distance L2. The launch strokes is
(L1-L2)x where x is a number of launch cords traverses or wraps
between opposing the distal moveable pulley blocks 125, 125' and
proximal moveable pulley blocks 135, 135', which includes the
addition of the launch cord center 150c when in the loading or
extending position as shown in FIG. 3B. In this example, L1-L2=7.5
inches and is multiplied by 4 (3 pulley wraps plus the addition of
1 to account for the leverage of the center cord 150c) and thus
produces a launch stroke of 30 inches.
[0045] Multiple parallel springs can be employed to engage each
distal moveable pulley blocks 125, 125' or proximal moveable pulley
blocks 135, 135', as shown in FIGS. 3A-3B via a connection to
moveable braces 127b, 127'b and 137b, 137'b, respectively.
[0046] As illustrated in FIGS. 3A-D, the launch cord release latch
170 and hand grip 161 can be attached to a moveable trigger
assembly 185 that can travel along the length of the elongated
center rail 110. As shown in FIG. 3C and 3D, at the top corners of
trigger assembly 185 are roller mounts 186a, 186'b and 187a, 187'b
(186a not show in these partial figures) that extend up through
slits that run the length of the bottom of the elongated outer
frame 111. Launch cord release latch 170, 170' extend through the
same two slits running the length of elongated outer frame 111 on
either side of elongated center rail 110. Attached to the ends of
roller mounts 186a, 186'b and 187a, 187'b are rollers 186, 186' and
187, 187'(186 not show in these partial figures) that travel within
the channel guide shape on either side of the elongated center rail
110. This configuration allows the launch cord release latch 170,
hand grip 161 and trigger assembly to travel the length of
elongated center rail 110 in both a proximal and distal direction
while staying permanently attached to elongated center rail 110.
This mechanism provides a method of drawing and releasing the
launch cord 150 via the grip 161 for either cocking or uncocking
the device. As shown in FIG. 3A-3C, the trigger assembly 185 is
permanently attached to a latch hook 181 that can connect and
disconnect from the stationary latch pin 162 that is permanently
attach to the mounting stock 160.
[0047] FIG. 4 is perspective partial view of the springs in the
extended position or projectile launch ready state. FIG. 5 is a
more detailed perspective view of the moveable pulley mechanism
attached to the springs in the extended position or projectile
launch ready state. FIG. 6 is a partial enlarged perspective view
of FIG. 4 and FIG. 5 that includes the nock of arrow projectile 10,
adjacent the distal moveable pulleys attached to the springs in the
retracted position. The launch or power stroke can be increased by
multiple wraps between the pulleys in the distal moveable pulley
blocks 125, 135 associated with opposing springs. However, as the
springs move simultaneously upon the release of the launching cord,
back to the rest or equilibrium position, while an inertial
limitation still exists, the contribution of each spring to the
launch velocity is additive, which combined with a large power
stroke rated by multiple pulley wraps can overcome these inertial
spring barriers and greatly increase the launch velocity of a
projectile such as an arrow 10. Further, additional springs can be
added in a parallel configuration to each of the moveable braces
connected to the moveable pulley blocks, as shown in the second
embodiment of FIGS. 3-6, to provide additional force, without
significant increase in physical dimensions, other than the minor
height increase transverse to the elongated center rail member
110.
[0048] As shown in FIG. 5, it also preferable that the moveable
braces 127b, 127'b that connect to the proximal ends of forward
spring members 120, 120' are connected by bridge 225, that extend
over and traverse the elongated center rail member 110. Bridge 225
also extends over any projectile such as an arrow 10.
[0049] As shown in FIG. 6, the launch cord center 150c is removably
attachable to a nock 300 of projectile such as an arrow 10 and
projectiles for release at the time of flight. The nock 300 is a
notch in the rearmost end of the arrow which serves to keep the
arrow in place on the string, or launch cord 150, as the bow is
drawn. However, in the case of complicated projectiles the launch
cord 150 may be coupled to the projectile through a more elaborate
intermediate assembly (not shown) that runs with the elongated
center rail 110, and the projectile launches from the intermediate
assembly. Hence, the elongated center rail 110 can be deployed to
guide the projectile. In the case of arrow projectiles, the track
can be configured minimally, but particularly not to interfere with
the flight of the arrow wings. In the case of other projectiles,
the elongated center rail 110 can be more substantial, and need not
be linear.
[0050] As discussed with respect to FIGS. 3-6, forward spring
members 120, 120' and rear spring members 130, 130' may be combined
in a parallel bank, each bank engaging one or more moveable pulley
blocks, but preferably four metal or composite coil springs in each
forward spring members 120, 120'and three metal or composite coil
springs are deployed in each rear spring member 130, 130'. The
spring tension within the forward spring members and rear spring
members should be balanced with the mechanical advantage of the
associated pulleys so that the forward spring members and rear
spring members retract simultaneously throughout launch. When using
uniform spring dimensions for each spring, determining the balance
can be done by matching the number of launch cord 150 connections
to each moveable pulley block with the number of springs in each
spring member, while the springs are in the extended position. As
an example, shown in FIG. 5, in the spring extended position, 3
launch cords connections are made at each of the moveable pulley
blocks attached to rear spring members 130, 130, thus each spring
member contains 3 springs. Similarly, 4 launch cord 150 connections
are made at both moveable pulley blocks attached to forward spring
members 120, 120', thus each spring member contains 4 springs.
Alternatively, different spring dimensions in the forward and read
spring members can be used to achieve balance with the pulley
advantage. The spring members are optionally metal or composite
coil springs. Springs are preferably deployed in tension, but a
configuration with at least some of the springs in a compression
mode is possible.
[0051] Further, to the extent some launching devices deploy metal
or other torsion springs that work to displace a pulley that
directs a launch cord, their performance can likely be improved by
adding a second moveable pulley or moveable pulley block connected
to a compression or tension spring to wrap the launch cord back to
the torsion spring member before it engages the projectile.
[0052] FIG. 7A is an top plan view of the outer frame as it
connects to the fixed braces, shown in the extended spring position
or projectile launch ready state, whereas FIG. 7B depicts the top
plan view with the outer frame omitted to better depict the fixed
and moveable brace connections to the springs in the extended
position, and FIG. 7C illustrates the top plan view with the outer
frame omitted to better depict the fixed and moveable brace
connections with springs in a position during retraction, and FIG.
7D illustrates the top plan view with the outer frame omitted to
better depict the springs in the retracted position.
[0053] Additionally, moveable braces 127a, 127'a and moveable brace
137a, 137'a can be used to allow free travel through fixed braces
220, 230, respectively, which are firmly attached to the inner
walls at opposing ends of elongated outer frame 111 and elongated
center rail 110. One or more bumpers 128, 128', are mounted to the
distal ends of moveable braces 127a, 127'a located on the distal
face of fixed brace 220, and bumpers 138, 138' mounted to proximal
ends of moveable brace 137a, 137'a located on the proximal face of
fixed brace 230, as illustrated in FIGS. 7A-D. In the extended
position, forward spring members 120, 120' forces draw the moveable
braces 127a, 127'a in a proximal direction, thus pulling the one or
more bumpers 128, 128' firmly against the distal face of fixed
brace 220 which is attached to elongated outer frame 111, and
simultaneous the rear spring members 130, 130' forces draw the
moveable brace 137a, 137'a in a distal direction, thus pulling the
bumpers 138, 138' firmly against the proximal face of fixed brace
230 which is attached to elongated outer frame 111, as show in
FIGS. 7A-B. During the process of retracting, forces in forward
spring members 120, 120' move the moveable braces 127b, 127'b in
the distal direction until a stopping point at which the launch
cord center 150c is held stationary, in turn, disengaging the nock
300 as projectile such as an arrow 10 continues to travel in a
distal launch direction. Simultaneously, forces in rear spring
members 130, 130' move the moveable brace 137b, 137'b in a proximal
direction until a stopping point at which launch cord 150 is held
stationary. Forces not imparted to the projectile 10, continue to
travel through forward spring members 120, 120' and rear spring
members 130, 130'. Forward spring members 120, 120' continue moving
in the distal direction and, in turn, push the moveable braces
127a, 127'a though fixed brace 220, thus moving the bumpers 128,
128' in a distal direction away from fixed brace 220 (attached to
distal end of the elongated outer frame 111), and simultaneously to
rear spring members 130, 130' continue moving in the proximal
direction and, in turn, push the moveable brace 137a, 137'a through
fixed brace 230, thus moving the bumpers 138, 138' in a proximal
direction away from fixed brace 230 (attached to the proximal end
of the elongated outer frame 111). One or more bumpers 128, 128'
and moveable braces 127a, 127'a continue moving in a distal
direction until counter-acting forces within forward spring members
120, 120' reach equilibrium and arrest their distal travel
progress, thus moving them back in a proximal direction and
returning one or more bumpers 128, 128' to their initial position,
flush against the distal face of fixed brace 220, and
simultaneously the bumpers 138, 138' and moveable brace 137a, 137'a
continue moving in a proximal direction until counter-acting forces
within rear spring members 130, 130' reach equilibrium and arrest
their proximal travel progress thus moving them back in a distal
direction and returning the bumpers 138, 138' to their initial
position flush against the proximal face of fixed brace 230, a
steady state, in the retracted spring position, as illustrated in
FIG. 7C and FIG. 7D. Hence, these configurations allow excess
forces not imparted to the projectile such as an arrow 10 to be
reabsorbed and resolved within the system without sustaining damage
to the system.
[0054] FIGS. 8A-C are schematic diagrams of the cord, pulley
blocks, pulleys and springs representing alternative configurations
tested in comparative examples with the illustrations showing only
the pulley blocks on one side of the center rail, including the
associated symmetric half of the launching cord. Further, pulleys
that rotate about a common axis or axle of a single pulley block
are shown in FIGS. 8A-C as vertically spaced apart to better
illustrate the launching cord path and a launch cord first end 150a
forming a terminal connection of half the launch cord 150.
Projectile such as an arrow 10 points in the direction it is
launched by forward spring members 120 and rear spring members 130.
FIG. 8C corresponds to an embodiment of FIG. 1 and FIG. 2. It
should be noted that the configurations in FIG. 8A and FIG. 8B both
deploy two pulley blocks 125, 135 and in each of two pulley wheels
126a, 126b and 136a, 136b, respectively, so that the launch cord
makes four wraps between the pulleys. In FIG. 8A, however, only the
proximal pulley block 135 is moveable as attached to the springs,
as the forward or distal pulley blocks 125 has been attached in a
fixed point of the distal end of elongated center rail 110. FIG. 8C
is as shown in FIGS. 1A-B, with only three pulley wheels utilized
in the two moveable pulley blocks. Two pulley wheels 126a, 126b
were placed in a distal moveable pulley blocks 125 attach to the
proximal ends of the forward spring members 120 and one pulley
wheel 136 in the moveable pulley block 135 attached to the proximal
spring (at the distal spring end), and the string or launch cord
150 ends terminated directly to the proximal springs 130. The bow
string or launch cord 150 now traveled around three pulley wheels
on either side of the center rail.
[0055] Comparative test results revealed that the configuration
illustrated in FIG. 8C generated superior arrow velocity and the
results are discussed in more detail in the TESTING section below.
However, a summary of the results concluded that associating each
moveable pulley blocks 125, 135 to move individually with a
tensioned spring members, forward spring members 120, and rear
spring members 130, respectively, or elastic member in the opposing
direction of the opposing pulleys in the block and tackle
configuration provided a higher launch velocity than if one set of
pulleys was not moveable or was fixed to the stationary part of the
embodiment, or the end of the launching cord was attached to a
fixed position with respect to the elongated center rail member
110. As each wrap of the launch cord 150 around a pulley 126, 136
introduces friction, it is desirable to minimize the pulley wraps
of the launch cord 150, while still obtaining the additive release
power and stroke distance of opposing springs: forward spring
members 120, and rear spring members 130.
[0056] FIGS. 9A-H are isolated views of rail mechanisms, such as
shown in FIGS. 1 and 7. FIG. 9A-C are depicted with a large
diameter projectile such as an arrow 10, and FIG. 9D-E are depicted
with a smaller diameter projectile such as an arrow 10. As
illustrated in FIGS. 9A-H, the elongated center rail 110 can be
configured with the addition of an over-molded center rail 112 to
raise or lower arrows of varying diameters in order to keep the
projectile such as an arrow 10 and arrow nock 300 in alignment with
launch cord center 150c. An over-molded center rail 112 is nested
on top of the elongated center rail 110 and configured such that
the over-molded center rail 112 can raise and lower while remaining
in parallel alignment with elongated center rail 110 in order to
accommodate arrows of varying diameters. On adjacent sides of the
over-molded center rail 112, angled notches have been positioned at
the proximal 112b, center and distal 112a areas of over-molded
center rail 112. Each of the notches 112c, 112'c, 112d, 112'd and
112e, 112'e of over-molded center rail 112 rest upon pins 113 that
are mountable into and along adjacent sides of over-molded center
rail 112. Notches 112c, 112'c rest upon pins 113a, 113'a, notches
112d, 112'd rest upon pins 113, 113' and notches 112e, 112'e rest
upon pins 113b, 113'b. FIG. 9F-H are a close up view of the
mechanism used to adjust the over-molded center rail 112. At the
proximal end of the over-molded center rail 112, an adjustment
screw 114 is mounted to the over-molded center rail 112 through
grommet 116. The distal end of adjustment screw 114 connects to
clevis end 117. A slotted linkage 119 then connects over-molded
center rail 112 to the clevis end 117 such that the slotted end of
the linkage is captured within the clevis end 117 via a clevis pin
118. When the adjustment screw 114 is rotated clockwise it draws
the over-molded center rail 112 in the proximal and upward
direction, as the angled notches in over-molded center rail 112
travel over the pins 113 mountable in the sides of over-molded
center rail 112, as shown in FIG. 9H.
[0057] FIGS. 10A-C are front and isometric views that depict the
positions of the hand grip as configured in an integrated cocking
mechanism. Additionally, the hand grip 161 may be configured in two
moveable pieces, moveable hand grips 161, 161' attached to trigger
assembly 185 with two hinges 183, 183', as depicted in FIG. 10A-C,
to aid in the cocking or uncocking the device. A scope mount 201
may also be attached to elongated outer frame 111 to mount a scope
200.
[0058] FIGS. 11A-F are partial side and top views of the passive
safety mechanism. Additionally, the mechanisms within the trigger
assembly 185 can be configured to passively activate a safety
mechanism (which prohibits the deployment of the propulsion system)
during the cocking process, as depicted in FIGS. 11A-F. In order
for trigger 180 to release the launch cord release latch 770, 170'
(and deploy the propulsion system), trigger 180 must rotate around
its axis pin 182, which rotates the top of trigger 180 in a distal
direction away from contact with pin 175 that is connected to the
launch cord release latch 170, 170'. When safety pin 174 is moved
into the proximal position (SAFE position), beyond ball stud 176
and into the safety pin catch groove in the top of trigger 180,
trigger 180 is not able to rotate into a position to allow launch
cord release latch 170, 170' to deploy the propulsion system, as
shown in FIG. 11E. Safety pin 174 is mounted to the end of a first
toggle arm 173a which is joined in a perpendicular position to a
second toggle arm 173b in a ridged fashion. Both toggle arms are
pivotable on axis pin 172 at the point where the first toggle arm
173a and second toggle arm 173b are joined. When the second toggle
arm 773b is moved upward it moves the attached safety pin 174 into
a SAFE position via the first toggle arm 173a. The pin 175 of
launch cord release latch 170, 170' is positioned below the second
toggle arm 173b. Launch cord release latch 170, 170' is mounted
within trigger assembly 185 via axis pin 171 so that launch cord
release latch 170, 170' may tilt backward (proximally) when the top
of launch cord release latch 170, 170' makes contact with the
launch cord center 150c and moves in a distal direction beyond the
launch cord center 150c, during the cocking process. As launch cord
release latch 170, 170' tilts backward its pin 175 moves upward
thus moving the second toggle arm 173b upward, and thus moves
safety pin 174 into a SAFE position, as illustrated in FIG. 11C.
Safety pin 174 can then be manually moved in a distal direction,
out of the SAFE position, in order to allow trigger 180 to be
actuated (and deploy the propulsion system).
[0059] In another configuration a launch cord release latch 170,
170' as shown in FIG. 11, is deployable to hold the launch cord 150
with attached projectile, such as an arrow (not shown) and at least
one of the springs in the extended position--until released by a
trigger 180. The springs can be metal or composite coil springs,
preferably tension springs, but can also be elastic materials, such
as rubber tubing and the like. Forward spring members 120, 120' and
rear spring members 130, 130' are mounted parallel to elongated
center rail member 110; however, as will be appreciated by those
skilled in the art, the forward spring members 120, 120' and rear
spring members 730, 130' can be mounted in different orientations,
with the attached moveable pulley blocks deployed to redirect the
launch cord 150 to propel the projectile such as an arrow 10 along
the center rail direction without departing from the scope of the
disclosure. Further, it should be appreciated that elastic energy
is generally stored in the launching cord, as well as the springs.
Hence, nothing precludes all or part of the launching cord from
being formed of a rubber or elastomer such as a band or tubing,
although this might only be desired in isothermal warm
environments.
[0060] FIGS. 12A-H are partial side and top views detailing the
anti-dry-fire mechanism. To further enhance safety, a mechanism can
be added to ensure that the propulsion system cannot be deployed
without an arrow nocked in the launch cord, as illustrated in FIGS.
12A-H. In the instant configuration, a string catch 164 is mounted
via hinge to the top of mounting stock 160. In the absence of a
projectile such as an arrow 10 connected by its nock 300 to launch
cord center 150c, string catch 164 is allowed to rest on the launch
cord center 150c in a position that is able to arrest the travel of
the launch cord center 150c from full deployment, as depicted in
FIG. 12C. The distal end of string catch 164 is shaped in an angle
that is slight proximal and downward to ensure that string catch
164 does not prohibit the cocking process. During the cocking
process, the angular shape of the distal end on string catch 164
encourages string catch 164 to pivot upward from its hinge mount,
allowing the launch cord center 150c to move in a proximal
direction, past string catch 164, without significant interference.
Additionally, as shown in FIG. 12G, a push arm 165 is connected to
the underside of string catch 164 via a hinge connection. The push
arm 165 extends downward and rests on top of the latch hook 181.
During the de-cocking process and in the absence of a projectile
such as an arrow 10, when latch hook 181 is lifted upwards, push
arm 165 is also pushed upwards, which in turn lifts string catch
164 upwards and thus out of contact with launch cord center 151c as
it travels down a distal path. This mechanism ensures that the
string catch 164 is prohibited from interfering with the launch
cord center 150c during de-cocking, even when a projectile such as
an arrow 10 is not engaged by its nock 300 to launch cord center
150c.
[0061] The trigger assembly 185 is configured to attach to the
mounting stock 160 via a latch hook 181 installed into the trigger
assembly 185. The latch hook 181 interfaces with a corresponding
stationary latch pin 162 that is located in the lower portion of
the mounting stock 160, as shown in FIG. 12C. This mechanism allows
the trigger assembly 185 and associated launch cord release latch
170, 170' to secure the launch cord center 150c in a fixed position
at the proximal end of the elastic projectile propulsion system 100
during the fully cocked or launch-ready state. The latch hook 181
may be disengaged from the corresponding stationary latch pin 162
in mounting stock 160 allowing the trigger assembly 185 to move
freely in the distal direction while de-cocking the device, as
illustrated in FIG. 12G.
[0062] FIGS. 13A-D are side and isometric views illustrating the
auto-retractable foot claw mechanism. In another configuration, the
elastic projectile propulsion system 100 may include a foot claw
221 to aid in the cocking process, as illustrated in FIGS. 13A-D.
In the present execution, the foot claw 221 is attached through the
spring wall 220 via two foot claw mounts 222, 222'. On the proximal
end of each of the foot claw mounts 222, 222' coil springs 223,
223' are attached to keep the foot claw 221 in the retracted
position against the elongated outer frame 111. This configuration
allows the foot claw to increases accessible foot space during use,
and then, when not in use, the foot claw space is minimized to
reduce potential interference with other operations of the elastic
projectile propulsion system 100.
[0063] FIGS. 14 A-C illustrates the adjustable stock; wherein FIGS.
14A-B are partial side views detailing the full range
adjustability, and FIG. 14C is a detailed proximal view of the
components of the stock release mechanism. As depicted in FIG.
14A-C, an adjustable shoulder stock may be included in the elastic
projectile propulsion system 100. A shoulder stock 231 is attached
to the proximal ends of two of the stock mounting rods 232, 232'.
The distal ends of the stock mount rods 232, 232' are mounted
through holes in mounting stock 160, elliptical holes in each of
the release buttons 233, 233' and holes in the spring wall 230, as
to allow the stock mounting rods 232, 232' to extend in a proximal
direction or retract toward mounting stock 160. On the surface of
each of the stock mounting rods 232, 232', running the length of
each rod, is a series of banded notches. As illustrated in FIG.
14C, the release buttons 233, 233' are inset mounted into either
side of mounting stock 160, and can pivot on axis bolts 235, 235'
within the inset pattern of mounting stock 160. The release buttons
233, 233' are maintained in their opposing, extreme positions of
travel via two coil springs 234, 234' such that their outer edges
each extend beyond either edge of mounting stock 160. In this
position, the inner edge of each elliptical hole within each
release buttons 233, 233' is encouraged into notches on the side of
each of the stock mounting rods 232, 232'. In this position the
stock mounting rods arc prohibited from extending or retracting.
Both release buttons 233, 233' can be pressed inward at the same
time in order to allow each of the stock mounting rods 232, 232' to
be extended or released. This configuration allows the stock to be
adjusted to fit users with varying physical needs and allows the
stock to be minimized during non-use in order to minimize potential
interference with transportation or storage of the elastic
projectile propulsion system 100.
[0064] FIGS. 15A-B are isometric, close-up, views of launch cord
tensioning terminals. It should be understood that the launch cord
150 first end 750a and second end 150b can be attached to the
proximal ends of the forward spring members, but preferably the
distal ends of the rear spring members 130, 130'. In at least some
configurations, the launch cord first end 150a and launch cord
second end 150b are attached to two respective launch cord
tensioning mechanisms located below the at least one proximal
pulley 136, 136' and the bottom of the proximal moveable pulley
block linkages 135b, 135'b, which allow the launch cord 150 to be
tensioned in fine increments, as depicted in FIG. 15 A-B. The
launch cord tensioning mechanism is comprised of cord end spools
151, 157' and ratchets 152, 152' which are mounted in fixed
positions to pulley wheel axels 739, 739', such that they rotate
when the top of pulley wheel axels 139 or 139' are turned with a
screw driver. Pawls 153, 153' attach to pulley block linkage pins
134, 134' and engage ratchets 152, 152' in a manner that allows
cord end spools 151, 151' to maintain launch cord tension after
pulley wheel axels 139, 139'are tightened.
[0065] The moveable pulley blocks are attachable to either the
distal or proximal spring members that deploy a plurality of
pulleys be configured such that each pulley in the block rotate
independently of the others.
[0066] However, alternatively, each wrap of the launching cord can
connect multiple pulleys that are attached to the spring ends, each
moveable pulley block having a single pulley.
[0067] FIGS. 16A-B are top views of an arrow retaining system with
springs extended and arrow loaded, and springs retracted arrow
unloaded. Additionally, the elastic projectile propulsion system
100 can be configured to launch arrows of widely varying lengths
and arrows that are shorter that the length of the draw or power
stroke of the device, as illustrated in FIG. 16A-B. When arrow
retaining spring 115, attached within elongated outer frame 111, is
located at the mid-point between the launch cord release latch 170,
170' and distal spring wall 220, the arrow retaining spring 115
maintains contact with the projectile such as an arrow 10
throughout the entire power stroke of launch cord 150. The
configuration ensures that arrow point 10a of projectile such as an
arrow 10 will exit the hole in spring wall 220 without making
contact with spring wall 220. The result is that shorter, lighter
weight arrows may be safely launched arid can attain higher arrow
velocity than longer, heavier arrows without any other
modifications to the elastic projectile propulsion system 100.
Methods
[0068] Methods include operation of the devices disclosed above. In
practice, a user obtains a linear projectile, such as an arrow,
mounts the projectile in the barrel of the device to engage the
launch cord. Once the projectile is secured within the device, the
user draws the projectile in a rearward direction to tension the
launch cords and extend each of the forward springs and rearward
springs. Thereafter, the user releases the draw on the projectile
(e.g., by pulling the trigger, releasing the launch cord, etc.),
which causes a transfer of energy from the tensioned springs and
launch cord to the projectile. Alternatively, the linear
projectile, such as an arrow, may be secured within the device
after the launch cord has been fully tensioned, and thereafter, the
user releases the draw on the projectile (e.g., by pulling the
trigger, releasing the launch cord, etc.), which causes a transfer
of energy from the tensioned springs and launch cord to the
projectile.
Testing
[0069] Various configurations of the propulsion mechanism were
tested to determine superior arrow velocity, as illustrated in FIG.
8A-8C. In all tests, the power stroke was 30'' for launching a 1
oz. (2.8.35 grams) arrow 33.5 inches (85.09 centimeters) in length,
with the arrow flight velocity subsequently measured with a
RADARCHRON.RTM. brand Doppler radar velocity sensor meter.
[0070] As shown in FIG. 8A, the propulsion mechanism was configured
so that the front pulleys 126a, 126b were held stationary as the
distal moveable pulley blocks 125 were attached to a distal, fixed
part of the center rail. The forward spring members 120, 120' and
rear spring members 130, 130' were connected into series attached
to the proximal moveable pulley blocks 135. The velocity result of
one test was 163 ft/sec (4968 centimeters/second).
[0071] The embodiment of FIG. 8B used the same four springs (two
springs being positioned on each side of the elongated center rail
110) as in FIG. 8A, however, forward spring members 120 were
attached to the distal end of elongated center rail 110 with the
distal moveable pulley blocks 125 (containing two pulley wheels)
attached to the proximal end of forward spring members 120, 120'.
The string ends were terminated directly to the forward springs
just under the distal moveable pulley blocks 125. Initial spring
tension was the same as the example described with respect to FIG.
8A. The launch cord 150, or bow string, traveled around four pulley
wheels in each moveable pulley block. The three flight test results
were:
[0072] 1) 197 ft/sec (6005 centimeters/second),
[0073] 2) 199 ft/sec (6066 centimeters/second),
[0074] 3) 196 ft/sec (5974 centimeters/second).
[0075] Variances in velocity were likely due to minor adjustments
made to the arrow rest between each test.
[0076] The propulsion mechanism was also configured as shown in
FIG. 8C as shown in FIGS. 1A-B, with only three pulley wheels
utilized in the two moveable pulley blocks. Two pulley wheels 126a,
126b were placed in a distal moveable pulley blocks 125 attach to
the proximal ends of the distally positioned, forward spring
members 120 and one pulley wheel 136 in the moveable pulley block
135 attached to the proximal spring (at the distal spring end), and
the string or launch cord 150 ends terminated directly to the
proximal springs 130. The bow string or launch cord 150 now
traveled around three pulley wheels on either side of the center
rail. The velocity result of `test one` was 210 ft/sec (6401
centimeters/second). Initial tension in the bow string or launch
cord was increased further by visibly removing slack from the
launch cord. While initial tension was not measured, it did not
appear to separate the extension spring coils. The velocity result
of `test two` was 228 ft/sec (6949 centimeters/second). Initial
tension was then further increased in the bow string or launch cord
150 so that the initial tension was taken from the spring,
separating the coils no more than 1/8''. The velocity result of
this test was 246 ft/sec (7498 centimeters/second).
[0077] While the highest velocities achieved during tests peaked at
339 ft/sec (1.033e+004 centimeters/second) utilizing a 270 grain
arrow at 30 inch (76.2 centimeters) draw length and 78 lbs (35.38
kilograms) draw force, it was discovered that some energy was lost
in the launch cord 150 being stretched. It is assumed that solely
utilizing a more robust launch cord 150 will result in greater
velocities.
[0078] As well, it was discovered after velocity testing concluded
that utilizing the same spring wire and outer diameter design with
a slight increase in spring length resulted in the ability to
generate equal or more energy in the power stroke with a
significant decrease in draw length. For example, the same spring
design used in all the tests was increased in length by 0.9'' and
resulted in the ability to decrease the draw length by 6'' while
generating a .about.2% increase in power stroke foot-pounds, all
with the same 78 lbs (35.38 kilograms) draw force. This was
achieved by increasing the initial tension in the springs via
tightening of the launch cord which increased the total amount of
force that was distributed over the length of the shortened draw
stroke. It was also realized that the addition of more pulleys and
resulting increase in pulley ratio would allow the use of shorter,
more powerful springs to distribute their force over similar or
greater draw lengths. It is reasonable to believe that future tests
are likely to reveal increases in arrow speeds as shorter, lighter
arrows matched to the reduced draw length, with a slight increase
in power stroke force will result in more velocity. As well,
overall device length can be reduced by a shorter draw length,
consistent with a more compact and maneuverable design.
[0079] Testing of the shock absorbing system described above was
conducted to assess damage caused to the entire system including
the elastic projectile propulsion system 100 as a result of
launching a projectile such as an arrow 10 not meeting minimum
current standards of weight to draw force ratio. The commonly
followed industry standard, set and maintained by the International
Bowhunting Organization (IBO), is prescribed in a ratio that states
an arrow typically weighs at least 5 grains per every one pound of
draw force (for bows generating arrow velocities above 290 feet per
second (8839 centimeters/second)). Testing was performed with
arrows weighing a little as 270 grains (30'' in length) at a draw
force of 78 pounds (35.38 kilograms), resulting in a testing ratio
of approximately 3.5 grains per one pound of draw force (generating
arrow speeds significantly above 290 feet per second (8839
centimeters/second)). Though testing was not conducted to the point
of failure, repeated launches did not result in any observed damage
to the elastic projectile propulsion system 100. While dry fire
tests (without an arrow) were not performed, it is believed that
parameters of the described shock absorbing system are capable of
being adjusted to achieve dry fire without damage to the elastic
projectile propulsion system 100. The demonstrated ability of the
propulsion system 100 to reabsorb stored energy not imparted to the
arrow upon release and thus launch lighter arrows at equal draw
forces compared to conventional bow systems provides an advantage
in the ability to increase arrow velocity without increasing draw
force or causing corresponding damage to the system.
[0080] While preferred embodiments of the present invention have
been shown and described herein, it will be obvious to those
skilled in the art that such embodiments are provided by way of
example only. Numerous variations, changes, and substitutions will
now occur to those skilled in the art without departing from the
invention. It should be understood that various alternatives to the
embodiments of the invention described herein may be employed in
practicing the invention. It is intended that the following claims
define the scope of the invention and that methods and structures
within the scope of these claims and their equivalents be covered
thereby.
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